Reworking of "Inorganic Polyphosphate is Required for Motility of Bacterial Pathogens" by Rashid et.al.

Inorganic polyphosphate (polyP) is a linear polymer of hundreds of orthophosphate residues linked by high-energy phosphoanhydride bonds. It is ubiquitous in nature (10), having been found in every bacterial, plant, and animal cell. Among the many functions proposed for polyP is a role in Escherichia coli in regulating the networks essential for responses to nutritional stringencies and environmental stresses and for survival in the stationary phase of growth (2, 15, 16). The regulatory role in E. coli is inferred from the behavior of null mutants of ppk, the gene that encodes polyP kinase (PPK), the enzyme responsible for the synthesis of polyP from ATP.

Inasmuch as some virulence factors are also expressed in stationary phase (11, 19), there may be a dependence on polyP for gene regulation in a pathogen (23). The relationship of polyP to virulence in pathogens is suggested by three observations: (i) massive accumulation of polyP in Helicobacter pylori during its infectious stage (S. Liu and A. Kornberg, unpublished data), (ii) sensitivity of the ppk mutant of Neisseria meningitidis to 10% human serum (22), and (iii) coregulation of capsular polysaccharide (alginate) synthesis and polyP accumulation in Pseudomonas aeruginosa (9).

Among these three pathogens and at least ten others, there is a remarkable conservation of the PPK amino acid sequence (reference 23 and C.-M. Tzeng and A. Kornberg, unpublished data). This list of pathogens includes P. aeruginosa, which causes infections in humans, particularly with cystic fibrosis patients, burn victims, and individuals with AIDS or cancer. Other pathogens in this list are Salmonella spp., the causative agents of typhoid and/or gastroenteritis; Vibrio cholerae, the cause of severe diarrheal disease; Klebsiella pneumoniae, an agent of pneumonia in humans; H. pylori, the cause of chronic gastritis and peptic ulcers; and Mycobacterium tuberculosis and Mycobacterium leprae, the agents of tuberculosis and leprosy, respectively.

Materials and Methods

Bacterial Strains and Plasmids. Preparation ppk null mutants of P. aeruginosa PAO1, V. cholerae 92A1552, Salmonella enterica serovar Typhimurium FIRN, and Salmonella enterica serovar Dublin SVA47, in addition to the available E. coli MG1655 and K. pneumoniae ATCC9621 mutants, were prepared.

Verification The ppk::tet mutation in P. aeruginosa and the ppk::kan mutations in V. cholerae and Salmonella serovars Typhimurium and Dublin were verified at the genetic level either by genomic PCR or Southern hybridization. Biochemical verifications were performed by assaying the loss of activities of PPK and exopolyphosphatase (PPX) (where appropriate) relative to the wild type and by the deficiency in polyP accumulation under defined conditions (unpublished data).

Motility Assay. Swim plates (1% tryptone, 0.5% NaCl) containing 0.3% agar was used to compare the motility of mutants with that of the corresponding wild-type strains.

Growth Assay. The growth of E. coli and P. aeruginosa wild-type and ppk mutants was monitored in shaking cultures at 30°C in tryptone broth.

Preparation of Bacteria Used for Microscopy. Cells were in exponential phase (0.4 to 0.7 optical density at 600 nm) grown in tryptone broth (1% tryptone, 0.5% NaCl) at 30°C.

Microscopy for Observation of Flagellar Swimming. ppk mutants of E. coli and P. aeruginosa along with their respective wild-types were examined under phase-contrast microscopy (magnification, ×800).

Results

ppk Mutants had Severely Impaired Motility in Semi-Solid agar Culture. As shown in Fig. 1 for P. aeruginosa, the mutant is severely impaired in motility compared to the wild-type. Since the P. aeruginosa ppk mutant still accumulates at least 20% as much polyP under some conditions compared to the wild type (unpublished data), the mutant was transformed with a plasmid overexpressing the yeast PPX (ScPPX1) (24) to deplete residual polyP. This strain behaved much like the mutant.

ppk Mutants were Rescued by Transfection with ppk Plasmid. When the mutant was transformed with a plasmid expressing P. aeruginosa PPK, the motility was completely restored. This clearly demonstrates the dependence of flagellar motility on PPK function. This observation has been extended to other pathogens (Table 1). Impairments of swarming in the ppk mutants were between 13 and 79% of those of the wild-type levels. As in P. aeruginosa, the motility deficiency of the mutant could be complemented in E. coli by introducing the ppk gene on a plasmid.

ppk Mutants Showed No Physical Growth Defects. No growth defect could be observed (Fig. 2) to account for the reduced swimming motility of the ppk mutants on semisolid tryptone plates. Electron microscopy revealed that the ppk mutants of E. coli, P. aeruginosa, K. pneumoniae, V. cholerae, and Salmonella serovar Dublin all possessed apparently intact flagella indistinguishable from those of the wild-type strains (data not shown).

ppk Mutants Showed No Defects in Flagellar Swimming. Direct microscopic observations revealed that the E. coli and P. aeruginosa ppk mutants were motile in liquid culture. Peritrichous E. coli and monotrichous P. aeruginosa change direction of movement by similar mechanisms, a reversal of flagellar rotation (21); in E. coli, reversal causes tumbling, and in P. aeruginosa, reversal causes the bacteria to back up. Microscopic analysis of the ppk mutants of E. coli and P. aeruginosa along with their respective wild-types, revealed no striking differences in changes of movement direction between wild-type and mutant cells. Possibly, more refined techniques will disclose the role of polyP in flagellar swimming.

Discussion

While ppk mutants had impaired motility, they possessed apparently normal flagella comparable to wild-type. Thus, the effect of polyP on swimming motility is likely due to altered functioning of the flagella.

Flagella are highly complex and conserved bacterial organelles requiring coordinated and ordered expression of about 50 genes for their synthesis and function (18). The roles of flagella in chemotaxis and motility are important for the survival of many organisms. A connection between virulence and flagellum-based motility has long been observed in many pathogens, some of which require functional flagella for virulence (7, 8, 12) and others in which motility must be suppressed for virulence (1).

The roles of flagella and flagellum-mediated motility in P. aeruginosa pulmonary and burn infections have been studied in detail (4-6, 13, 20). In the pathogenesis of respiratory tract infection, it has been shown that flagella and/or flagellar motility are necessary at three distinct stages of infection: (i) acquisition of motile organisms, (ii) immunostimulation, and (iii) adaptation (6). Flagellar motility and type IV pili-based twitching motility have been found necessary for the development of a P. aeruginosa biofilm (14). Bacterial biofilms are troublesome when they form on tissues, on catheters, or on medical implants because of their innate resistance to antibiotics and other biocides (for a review, see reference 3). We have found that the ppk mutant of P. aeruginosa is also defective in twitching motility and biofilm formation on abiotic surfaces (data not shown). Taken together, these several lines of evidence suggest that PPK or polyP might be a virulence determinant of pathogens, like P. aeruginosa.

BS302 Practical 4 Team Work Sept 15 2007

Group # 7

1.reduction of introduction to 50 % of actual length... good to know and need to know...

Inorganic polyphosphate (poly P) is a linear polymer of hundreds of orthophosphate (Pi) residues linked by ATP-like, high-energy, phosphoanhydride bonds and found in all microbes (1). The enzyme responsible for the synthesis of poly P in bacteria is poly P kinase (PPK), which polymerizes the terminal phosphate of ATP into a poly P chain (2). One of the functions of poly P in Escherichia coli is a regulatory role inferred from the inability of the ppk mutant to adapt to nutritional stringencies and environmental stresses and to survive in the stationary phase of growth (3, 4). These defects of the ppk mutant have been attributed partly to the failure to express the rpoS gene that encodes ^s, the stationary phase  factor (5).

PPK is highly conserved in many bacterial species, both Gram-positive and Gram-negative, including some major pathogens (6). From previous research, the ppk mutants of the pathogens were moderately defective in flagella-mediated swimming on semisolid agar plates (9). In addition, the P. aeruginosa ppk mutant is defective in a newly discovered swarming motility dependent on flagella and in a previously characterized twitching motility that depends on type IV pili (10).

Biofilms are sessile microbial communities formation of which are initiated by surface attachment of individual planktonic bacteria, followed by cell-cell interactions that develop into growing colonies in an elaborate three-dimensional structure (11). Recent genetic screens of biofilm-defective mutants in E. coli, P. aeruginosa, and V. cholerae have revealed that initial surface interaction followed by microcolony formation and enlargement are mediated by force-generating organelles: flagella and pili (14-16).

Bacteria communicate their cell density by quorum sensing to coordinate the expression of particular genes (19). Among quorum-signaling molecules or autoinducers (AIs), homoserine lactones (HSLs) control expression of extracellular virulence factors (e.g., toxins, elastases, and proteases) and small-molecule, secondary metabolites (e.g., rhamnolipid, phenazine, and cyanide) in P. aeruginosa (20). The lasR-lasI system generates the AI-1 signal (N-(3-oxododecanoyl)-L-HSL) while the rhlR-rhlI system generates the AI-2 signal (N-butyryl-L-HSL). Of these signals, only AI-1 is required for the normal maturation of P. aeruginosa biofilms (18). With regard to twitching, the AI-2 signal is absolutely necessary whereas the AI-1 contribution is only partial (35% residual twitching in the lasI mutant) (32).

P. aeruginosa is an important pathogen in the environment affecting many organisms, including humans. The success of P. aeruginosa in diverse environments is attributed to its impressive arsenal of virulence factors, which include multiple cell-associated factors (e.g. flagella and pili) and secreted virulence factors (e.g. elastases) as well as small molecules (e.g. rhamnolipid) (20, 33). The burned-mouse model has been successfully used to demonstrate the essential roles of different quorum-sensing components of P. aeruginosa (41).

In this report, we demonstrate that poly P and PPK are essential for quorum sensing and virulence of this clinically important pathogen. This result identifies PPK as a target for the development of a new class of antibacterial drugs.

2. rewrite third sentence of abstract...

The mutation is aberrant in quorum-sensing, leading to severely reduced synthesis of quorum-sensing controlled virulence factors including elastase and rhamnolipid.

3. materials and methods rework format... could it be that it is the instructors have changed it? 

There are 2 possible solutions:

(a)    Italicize the title of the 4^th paragraph, “Bioassays”. Then, merge and categorise the 4^th paragraph  as a subparagraph under the third paragraph, “Extraction and Bioassays of AI-1 and AI-2”. At the same time, italicize the first word, “Extraction” and change the font to Arial form.

Original:

Revised:

(b)   Change the heading to as follows:

4.rewrite of second paragraph of results and discussions 

ppk mutation leads to reduced synthesis of Autoinducers and Extracellular Virulence factors.

done for mtDNA mutations increase tumorigenicity in prostate cancer. group work, minimal contribution by yy. laser inclusion exclusively yy idea.

BS 302 Practical 3

Done by GROUP 15

Prostate Cancer May Be Maternally Inherited!

Generally, mutations in mitochondrial DNA (mtDNA) have been associated with the etiology of cancers. Recent studies by researchers from Emory University have illustrated its link to prostate cancer. As the cell’s power house, the mitochondrion contains its own genome which is maternally inherited. During the process of energy generation, free radicals are produced through oxidative phosphorylation. This study has shown that mutations in the cytochrome oxidase subunit I (COI) gene would result in the inhibition of oxidative phosphorylation, thus increasing the free radical production. At high levels, its tumorigenic activity would override its normal function of cell proliferation.

Using Laser Capture Microdissection (LCM) technology, various mtDNA variants were isolated and identified. The researchers have decided to focus on the COI mutation and attempt to unveil its relationship with prostate cancer in this study.  Data have shown that patients with prostate cancer exhibit a higher mutation frequency in the conserved amino acids of the COI gene, as compared to the general population. The cause of prostate cancer may be germ-line or somatic based. The presence of ancient COI protein polymorphism, a phenomenon widely observed in African-Americans, could bring about a higher risk of prostate cancer through germ-line inheritance.

Animal studies were performed using novel cybrid studies. This involves the fusion of two cells, obtaining a cellular hybrid which contains mutant mtDNA that encodes for a defective ATP6 protein. When ATP6 mutation was introduced into mice, it reduces ATP synthase activity and causes an increase in free radical production. This results in a 7-fold increase in tumor size as compared to the control mice.

Through the above findings, the researchers had shown the association between mtDNA mutations with prostate cancer. These mutations have led to higher free radical levels. By inferring from the prevalence of the COI mutations in the general population, it is recommended that elderly should go for preventive diagnostic checkups.

Company Overview

For this case analysis, this student has chose to focus on a financial services group, Prudential, Prudential Corporation Asia, in Singapore. Prudential is an “international retail financial services group” providing services such as life and pension assurances, insurance, asset management and banking. Various brand names come under the umbrella group of Prudential, including egg, a Internet banking company, Prudential, providing life insurance operations in the United Kingdom and Asia, Jackson National Life Insurance Company, providing life insurance coverage in the United States and M&G, providing fund management services in the UK and Europe.

In 2005, Prudential achieved operational profit of £1,712 million from all operations, with over £234 billion funds under management. With employees of over 23,000 in 21 countries such as United States, United Kingdom and Singapore, it serves over 21 million customers, policy and unit holders. Integrity and security have been the company’s keywords since its inception almost 150 years ago in 1840. 

Prudential first entered Asia in 1929 through India. It has now expanded to 12 Asian countries, with China and Vietnam the latest additions in 2005 and 9 of them providing asset and fund management operations. Prudential has now the largest coverage in terms of life insurance operations in Asia and is consistently in the top five in market positions. Furthermore, Prudential is also one of the largest foreign owned companies providing fund-managing services.

The lists of products provided by Prudential in Asia include savings, protection and investment, with each product adapted to each individual market. According to the last count, Prudential has a vast network of 170,000 agents providing services to over 7 million customers in Asia alone. Sales in this region grew by 23 per cent in 2005 and this represents almost half of Prudential Group’s new business profits.

In Singapore, Prudential has been with us for over 75 years, being established in 1931. Prudential has won various awards in Singapore including Life Insurer of the Year award in 2000. Furthermore, it has made an effort in promoting corporate social responsibility, allowing it to claim the Friend of the Arts award in recognition to their contribution towards the society. Prudential has over 3000 insurance advisors and 400 staff and is the top three insurers in Singapore taking a part of about 75% of a SGD 3.3 billion industry.

Singapore Insurance Market Overview

Singapore is a premier insurance center in Asia, with overall per capita spent on insurance to be about USD 1744, after Hong Kong’s overall per capita of USD 1977. In 2001 the insurance market has over 49 registered insurance players, even though the general insurance market is relatively small and many considered it to be saturated. However, the role of Singapore as a major regional service hub and major shipping center fuels the growth of this sector. This has led to thinner margins by the players due to higher competition, but with the increase in premiums with the overwhelming ramifications of the September 11 attacks, it has enabled general insurance companies such as Prudential to consolidate their gains.

The Singapore life insurance market scene is mainly played out by 14 players, including Prudential, Manulife and Aviva. This has led to some people criticizing the saturation of the market even though the number is considered by some to be as moderate. However, this could inhibit the introduction of new players into the market as the scene is already concentrated and only moderate gains could be posted for a new company.

However, there are still many opportunities related to the general insurance markets for interested global financial institutions and investors. This is due to the loosening of policies by the Monetary Authority of Singapore, resulting in the liberalizing of the market. Policies such as opening of entry to direct insurance, 49 per cent foreign shareholder limit, opening of admission policy for new insurance brokers, liberalization of the investment limits of general and life insurance funds and various tax incentives targeting captive insurance and offshore marine hull insurance activities.

As mentioned, the total worth of the insurance industry is over SGD 3.3 billion in gross premiums paid out, with the strongest growth of 30 per cent in offshore insurance business capturing half of the SGD 3.3 billion market. The domestic market posted increases in line with the GDP growth of around 10 per cent, constituting the other half of the market. The table summarizes the various gross premiums associated with the various offshore and domestic markets. Note the strong postings in motor insurances in the domestic market and the strong growth in the marine and aviation sector.

Table 1Table of earnings of the insurance industry.

However, the losses to claims were significant at incurring loss ratio of about 64 per cent for the domestic market, with the miscellaneous category, posting a loss ratio of about 45 per cent and the motor market having an 87 per cent ratio. The trends for the loss ratio is expected to declare a negative downward sloping tendency with increasing premiums as mentioned above due to the global situation. However, of workman’s compensation category there is an expected increase in loss, currently standing at around 88 per cent contributed in part by the rising medical costs and increase in common law claims. The table below demonstrates the growth and trends of the industry.

Table 2Table summarizing performance of the industry.

In 2000 alone, more than 600, 000 policies were sold with a total insurance coverage of just below SGD 30 billion. In total, over 4 million policies were in effect with providing more than SGD 200 billion, with an estimated three quarters of the population covered under the various insurance policies. With the increased awareness and education of the public on the need for retirement and asset management this sector is expected to grow.

Prudential Corporation Asia, Singapore

The vision of Prudential Corporation Asia, Singapore is to be the best in customer focus, creating value for shareholders and to attract the best people. This underpins their values on integrity and creating trust with the customer. Furthermore, they claim to be the trailblazers in establishing trends and products.

For example, they were pioneers in the introduction of investment-linked life insurance products and the first insurance company in Singapore to introduce a credit card where premiums could be paid through points earned from spending using the credit card. As a customer oriented initiative, Prudential Corporation Asia, Singapore also introduced a “Plain English” initiative with policies explained to customers in simple terms to help customers better understand their benefits from the policy and their rights in the contractual obligations within the policy.

Furthermore, as outreach to the community, various community projects were sponsored by Prudential Corporation Asia, Singapore, including a children’s theatre festival named Prudential Children’s First.

The two broad products offered by Prudential Corporation Asia, Singapore are insurance coverage and unit trust, asset management. They stress on the flexibility and adaptability of their products to be able to cater to any customer, with their unique icon of a woman examining a mirror they remind the customer that Prudential truly ‘listens’ to and respects them.

With the above image in mind, Prudential Corporation Asia is clearly positioned as a middle market; personalized insurance coverage and asset management company targeting the middle aged blue collar workers and family builders of Singapore. This is clearly demonstrated by its efforts put in to “listen” to the customer, initiation of investment linked insurance policies for busy citizens who do not take the time for investment and research and the introduction of a credit card linked to insurance premium who only take short term plans for the future, wanting tangible and quick gains now.

With these products further augmented by designated insurance agents and personalization of products, this has been translated into creating capabilities of the company and has become essential core competencies that separate them from the competition.

Thus, with these core competencies and clear positioning, Prudential Corporation Asia has a competitive edge in this cutthroat insurance industry in Singapore. By providing more scope for the personalization of the policies such as increased coverage and bundling of credit card to other products and discounts and providing better services and products through the continuing improvement of technologies such as increased connectivity of company to customers via the internet, Prudential Corporation Asia will definitely be able to strengthen on existing competitive advantages and transform them into permanent and prolonged competitive advantages.

Furthermore, the community involvement projects serves to increase the awareness and highlight the contribution of Prudential Corporation Asia, Singapore to the children of Singapore. This will directly positively impact the parents of the children who are the targeted segment of the company. With continued support to the local arts scene and support to children activities Prudential Corporation Singapore can definitely build on its business and yet contribute back to the society.

However, with every move there is a negative and opposite reaction. With increased personalization, policies may be taxing to sell and the funds available for investments would decrease with time. More time has to be spent to gather the premiums to have a sizable return for the company. This can be countered by leveraging on the parent company and place investment under one umbrella, producing an increased pot of funds for the investments.

Competitors

Manulife Singapore

Manulife Singapore is under the premium Canadian financial service conglomerate that has links in 12 countries. They too provide various financial products and investment plans. They have a worldwide premium and deposit of over USD 65 billion, increased by 5 per cent from 2005; with more than USD 400 billion under their management they are the largest insurance company in Canada. Furthermore, with the recent 2005 merger with John Hancock, they have more than doubled the funds Manulife Financial has handle from before the merger. Boasting a total capital of more than USD 30 billion, Manulife Financial and Manulife Singapore take pride in their work as professional life insurers. Once again, integrity and professionalism are the key phrases Manulife holds onto and is one of only two life insurance companies with Standard and Poor’s highest triple A rating. Having a People’s Developer certification under its belt, Manulife Singapore hopes to achieve an image of an old friend whom one can always count on for help and advice.

Aviva

Aviva Singapore

The world’s fifth largest and United Kingdom’s largest insurance group, Aviva is the premium providers for life insurance and pension products. In 2006, Aviva managed a operating profit of more than £3 billion and total sales of close to £20 billion. Accessing more than 20 countries, Aviva has more than £300 billion under its management it focuses mainly in long-term savings in the United Kingdom and Europe and no frills, low cost, single premium life insurance in Singapore. Employing more than 50,000 employees worldwide they project an image of life and vitality. Its bright yellow and sky blue branding only serves to accentuate the image that Aviva is a fun, innovative, progressive and no frills company. Customers will trust Aviva to help them make the most of their life.

Prudential Forte

As we have seen, each company focuses on different aspects of projecting images to the customer, especially in this cutthroat world of insurance sales. Manulife banks on a professional teacher image, willing to impart and point the way for the customer. Aviva projects an image that customers can have fun, live life to the fullest and celebrate vitality when customers trust them.

However, one of Prudential’s strengths is that it portrays an image of a person (preferably female) listening attentively to your every need. This image differs from the other companies projecting an image that identifies with the customer, whereas Manulife is more top-down and Aviva is bottom-up approach. This powerful image is the key strength of Prudential.

Furthermore, Prudential empowers the customer through its “listening” image and effecting personalization of policies after consultations with the customer. This is especially important in the context of Singapore, as people tend to be cold and calculating, lacking the warmth of friendship and family. A friendly and fresh image will be able to capture the hearts and minds of the customer. This friendly approach and supplying what the customer wants and needs is another key strength of Prudential.

Denying Prudential

However, there is a flipside to this image of a caring friend that is you cannot be someone’s friend in just a short time. Trees do not just grow up in a day and friendship does not mature in just a few consultations.  Therefore a major blockage to Prudential in the Singapore market would be that Prudential would be just another “face in the crowd”. Especially so in the saturated insurance market that is Singapore. Therefore it is necessary for Prudential to increase its image exposure, preferably with activities that will induce a positive response to the company. This is probably why Prudential has undertaken various community projects with children and in support of the arts in Singapore, all done to augment its image of a caring individual to society and people.

Menacing Prudential

One of the potential threats to Prudential or the insurance industry in general would be the ever-rising health care costs. As Singapore walks towards an aging populations and the ever-rising threat of new and deadly pathogenic diseases, the cost of health care and drugs would spiral up to the heavens with little hope of parachuting down. The projection of 6 million citizens in the future, it is conceivable that at least one third of the total population, 2 million, would be above 50. The increase in health care costs will decrease the margins of Prudential as claims may override the premiums collected.

Furthermore, with the baby boomers at retiring age, a sizable decrease in savings will probably surface, as the grandparents do not want to save anymore but to withdraw all their money for holidaying and other pursuits, perfectly suited for Aviva, with its low premium life insurance policies. This will result in less premiums and investment funds for Prudential, forming a sizable threat in the future.

Prospecting Prudential

Some opportunities have surfaced with the aging population for Prudential, such as travel insurances for holidaying grandparents, tapping into the motor and offshore market. Prudential’s strength in molding the perfect policy for different customers could be implemented to take full advantage of these opportunities.

Achieving Full Prudential

We have seen look at a life insurance company Prudential Corporation Asia Singapore and its parent company Prudential and skimmed through some details of its inception and how it works. We also have seen some aspects of the life insurance industry of Singapore in general terms and we looked at some of Prudential’s competitors in Singapore. Finally we tried to analyse some broad aspects of Prudential’s competitive advantages, weaknesses, threats and some phenomena in the industry Prudential can take advantage of.

For insurance companies such as Prudential, one will have to implement direct marketing programmes, to directly reach the customers. Through dedicated agents excelling in company polices and philosophy. Agents who accentuate the image and branding of the company, is probably the most effective way to market the product.

However, community involvement projects such as participation in children’s and arts events could theoretically increase the profile of Prudential and market the company that cares. This will increase the exposure of the image and branding and will most likely augment the first impressions of the agents out on direct marketing standing at the MRT stops and hanging around the place like vultures, swooping in if the target looks old enough and dressed smart enough to have some disposable income.

Finally, there are several segments that Prudential could focus on next, which includes the motor industry and holiday insurance.

This concludes the case analysis of Prudential; I hope you have enjoyed reading it at least as much as I have enjoyed writing it.

http://ccforum.com/content/10/5/R137 

the link to the article...

Summary

Title of Study

The Role of Body Mass Index and Diabetes in the Development of Acute Organ Failure and Subsequent Mortality in an Observational Cohort (Katarina Slynkova 2006)

 the link to the article...

Study Objectives

This paper studies the influence of diabetes in the obesity-associated complications, whether the presence or absence of diabetes will result in higher risks of development of organ failure resulting in death.

Methodology

A random study was carried out for a previous study, Atherosclerosis Risk in Communities (ARIC) and results were used for this analysis of obesity and diabetes on the prevalence of developing organ dysfunction and subsequent death. Sample size was 15408, after disregarding missing data (confounding factors). Participants of the study were aged between 44 and 66 years, representative of the population demography of the population studied based in the US from 1986-1989.

Variables important to this analysis were, value of BMI, diabetes status, and presence of acute organ failure. BMI, Body Mass Index, is weight of participant divide by square of height of participant. It is an estimate of the participant’s level of obesity. A straight yes/no response or a fasting blood glucose level of above 126mg/dl of the participants confirmed diabetes status. However, the data could not differentiate between types 1 and 2 diabetes. The International Classification of Disease, 9th Revision defines acute organ failure. The classification made up of codes for each system dysfunction; indication of either one of the codes upon the hospitalisation summaries of a participant is development of ‘acute organ failure’.

From the above variables, questions that the researchers wanted to have answered are: how do the variables affect the,

1. Risk of acute organ failure occurring three years after study.
2. Prevalence of death after hospitalisation due to organ failure.
3. Prevalence of death three years after study.

To analyse the data, multivariable logistics regression and Cox proportional hazard regression were used. Multivariable logistics regression was used to find correlation between the variables and,

1. development of acute organ failure,
2. death within three years,
3. and death after hospitalisation due to acute organ failure.

While Cox proportional hazard regression is used to find the probability of acute organ within three years with input from variables, such as body mass index and diabetes status.

Results

There were 5 major findings made by this analysis.

1. BMI≥30 has higher prevalence of diabetes.

52% of participants BMI≥30 has diabetes compared to 24% of participants with BMI<30.

2. BMI cannot predict development of acute organ failure.

Probability of development of acute organ failure for ideal (BMI 21-24), overweight (BMI 25-29) and obese (BMI≥30) participants are similar (0.9%, 0.8%, 0.9%).

3. Diabetic participants are more likely to develop acute organ failure.

Acute organ failure of diabetic participants is higher than non-diabetic participants. (2.4% vs. 0.7%, p<0.01)

4. Diabetic participants more likely to die after hospitalisation from acute organ failure.

2.4% of diabetic participants after hospitalised from acute organ failure die, whereas, 0.7% non-diabetic participants die after hospitalisation from acute organ failure.

5. Diabetic participants more likely to die within a three-year period.

51.2% of diabetic participants do not survive for more than three years, however, 21.1% of non-diabetic participants die within three years.

Discussion and Conclusions Drawn

This study confirms the link between high BMI (≥30) and diabetes. However, high BMI itself does not affect the prevalence of acute organ failure. It is the presence of diabetes and its accompanying effects such as hyperglycemia and insulin resistance that contributes to higher acute chronic organ failure rates.

The authors acknowledge the limitations of their study including the following:

1. Coding of organ failure has tendency to underestimate true number of organ failure cases.
2. Missing data on hospitalisation and development of acute organ failure, patients may not be admitted to hospital after acute organ failure.
3. Period where study was conducted (1980s), studying of old data.
4. No separation between diabetic patients, no differentiation between type 1 and type 2 diabetes.
5. Short follow up period of three years, long term effect of high BMI cannot be ascertained.

In conclusion, the authors feel that the presence of diabetes has a higher impact on the health risks than high BMI. Although, high BMI would increase the likelihood of development of diabetes, BMI itself has no correlation to any changes in rate if acute organ failure.

Comment (Statistical Methods)

Study is on prevalence of acute organ failure and subsequent death after hospitalisation, with respect to high BMI and diabetes status.

Multivariable Logistic Regression

Multiple regression is to be used as dependent (acute organ failure) are correlated to multiple variables, such as high BMI and diabetes status. A simple linear regression is not powerful enough to determine this correlation.

However, multiple regression assumes that population distribution is normal, this is a wrong assumption for this study as acute organ failure is a categorical variable and is not possible to display a normal distribution.

Therefore, instead of relying on non-parametric methods, which are cannot test for interaction between variables. A logistic distribution is assumed for acute organ failure, a dichotomy categorical variable. Thus applying multivariable logistic regression to the analysis of acute organ failure with influence by BMI and diabetic status is a correct decision.

Cox Proportional Hazard Regression

Cox proportional hazard regression was used to find out the probability of acute organ failure within a fixed time period of three year for all participants.

This model is the most general of regression models; it does not have any underlying assumptions regarding the distribution of population data. Since time to acute organ failure in such a short time frame has low possibility of adopting a normal distribution parametric methods cannot be used as the distribution of the population cannot be accurately estimated.

Although Cox proportional hazard regression can be considered as a non-parametric form of analysis, it is more than sufficient to analyse the data. Furthermore the study involves a large sample size of around 15000 participants, this analysis was able to determine how the development of acute organ failure with influence from BMI and diabetes in participants was correlated with time.

Comment (Validity)

Based on the appropriate analysis done by the researchers, there is validity of the conclusions drawn, but with certain limitations. The conclusions were only valid for short time frames; nothing could be concluded about the long-term risks of high BMI on the development of acute organ failure. However, the study highlights the increased risk of patients with diabetes mellitus to suffer from acute organ failure, resulting in death in three years.

However, due to this student’s ignorance, verification of results could not be presented in this assignment. Although, the student understands the underlying assumptions surrounding multivariable logistic regression and Cox proportional hazard regression, this student has not clue how to apply the data to these statistical methods. This student apologizes for his ineptitude.

Katarina Slynkova, David M Mannino, Greg S Martin, Richard S Morehead, Dennis E Doherty. 2006. The role of body mass index and diabetes in the development of acute organ failure and subsequent mortality in an observational cohort. Critical Care.

When people speak of viruses, they often classify them together with other disease causing agents such as bacteria. However, in the eyes of the biologists, there is an inherent and big difference between these two classes of microorganisms.

Bacterial cells are similar to cells in our body, they are termed as ‘alive’, and they move around within their environment and do most of the things our cells can do. However, whether viruses are alive have been debated since Wendell Stanley isolated the components of the tobacco mosaic virus, simply because they do not fit into the conventional norms of a living organism.

Proponents of the virus are alive school of thought argue that since they have a complex mechanism for the infection of other organisms, these little critters must be alive and ‘intelligent’ enough to accomplish such complex deeds.

To underline how complex it is to enter a foreign cell, imagine that you are a virus blind, floating around and you feel something familiar on the surface of a specific cell (cell surface proteins). You then change the conformation of your outer covering, a protein coat, to inject your insides, your genetic information, through the impermeable layer of fats, cell membrane, that surround the cell all without lifting a finger. Surely to be able to do this is to exhibit intelligence and ‘life’.

However, this sort of intelligence may inherent in other ‘non-living’ elements too. A good example would be the enormous amount of genetic information that scientists have termed as ‘junk DNA’, as they do not have any significant impact on the cell; they are just there in the cell. Some of this ‘junk DNA’ known as transposons have the ability to move around within the entire DNA sequence in a cell.

Just like viruses they are bits of genetic material having the ‘intelligence’ to get up from one place and move to another as they see fit. To illustrate the difficulty of this operation, one can try to board a plane from London to Singapore with a bottle of lemon tea at the height of a terrorist scare. So does viruses have true ‘intelligence’?

Maybe why viruses should be alive can be attributed to its ability to evolve in the face of the changing environment. One key feature of any living organism is to be able to survive in the merciless environment where the strongest survive, of which the most successful would be us. Evolution drove the creation of the dreaded SARS virus that managed to keep ahead of the cocktails of vaccines that we concocted. The strongest does manage to survive in the viral world.

On the other hand, the strongest may not be the most successful; the best adapted of the viruses may have priority in self-propagation in the hosts. However with the increased efficiency of killing the host cells to produce more viruses, they are in fact limiting their numbers, as there are simply no more host cells to infect. The Spanish Flu in 1918, although killed millions however only survived for 18 months before it just died off. Maybe viruses exist just simply because they can and not because they are alive.

In the end, maybe we should not be entirely be concerned about whether viruses are alive, but to accept it that they are part of the natural world that we live in.

what is right and what is wrong? the fundamental question that everyones asks everybody else... we should all face activities with passivity... only that way can we see the end result of the activity and can from there direct the flow of the activity towards the result...

but it is always easier said than done... especially when emotions and adrenaline (epinephrine) overloads the sensory system... i would guess i am what they call an impulsive person... i have removed some of the censoring agents in my brain... thus i can act according to whim and fancy... and do silly things that normally people would not do... i guess there would be no possibility for me to play in any team competitive games... i would be subjected to the whines and insults and whatever gamesmanship that the opponents can throw at me... 

i would get into a rush of blood to the head and start to feel that the world has owed me something for too long and i am going to get it back by hook or by crook... maybe that is one of my shortcomings... but would anyone in that frame react the same way as me? obviously not... so there is something that is different in me that does not conform to normal tendencies...

but why? why is there such a reaction? do i really feel mad about something? i do... but when i try to recall the incident... all i can come up was a shame of doing something that is totally inadvisable... and the reason for the trigger was extremely trivial... so trivial i was ashamed to face it... why then? i guess the reason is that i do not have enough experience on this sort of things...

i am still only a boy and not yet a man... trying to be one but failing terribly... but we all can try.. so that is not really a problem... we are just passing through here...

mommy its over...

Discharge Report (SI2006)

Name: Tan Ying Yang

Department: Logistics

Date: 060606

Job Description

1. Assist in drawing up of floor plan.
2. Sourcing for contractors, set up of event area (Toa Payoh HDB Hub Area C).
3. Liaise with Student Affairs Office, Nanyang House, Centre for Educational Development and Office of Facilities Planning and Management.
4. Collection of goodie bags items.
5. Assist in packing of goodie bags.
6. Transportation of goodie bags and other required logistical items to event area.
7. Liaison with contractors for the setting up/tearing down of event area and delivering of food.
8. Maintenance of event grounds during event.
9. Transport of loan and logistical items back to NTU.

Execution Process

Pre SI 2006

1.      Assist in drawing up of floor plan.

Floor plan was decided and drawn up by the management committees of both SI 2006 and EnviroFest. Both events were planned to run concurrently with EnviroFest rounding off the event on the last day, thus the floor plan has to accommodate both events.

2. Sourcing for contractors, set up of event area (Toa Payoh HDB Hub Area C).

Contractors were sourced according to the requirements of the floor plan. Company engaged finally was ¹. Catering was order according to the number teams already registered and the projection of 4 members per team and 1 teacher. Catering company engaged was ².

3. Liaise with Student Affairs Office, Nanyang House, Centre for Educational Development and Office of Facilities Planning and Management.

SAO approval was required for loan of items from Nanyang House, CED and OFPM.

4. Collection of goodie bags items.

Biz Mag department sourced goodie bag items and the collection was done by the logistics department. Toyota LiteAce van was rented from ³.

5. Assist in packing of goodie bags.

Goodie bags were packed at the EarthLink room the weekend before the event.

6. Transportation of goodie bags and other required logistical items to event area.

All transportation was done the day before the event. Nissan Cabstar Truck was rented from ⁴.

7. Liaison with contractors for the setting up of event area.

Area was set up the night before the event through the work of contractors. Floor plan was adjusted accordingly to ease set up.

During SI 2006

1. Liaison with contractors for the delivering of food.

Catered food was delivered according to programme, judges, guest of honour and participants were fed. Quantity of Muslim food was increased for the last day to accommodate the EnvorFest event. Vegetarian food was not indented as catering company has problems supporting the small quantities required. Vegetarian food was then purchased from food courts in the area.

2. Maintenance of event grounds during event.

Wear and tear of the event grounds and the logistical items requires the department to monitor the situation closely on the ground. Main problem on the first day was the lack of power to the booths set up by the contractors. Logistical department was also at fault as we did not anticipate this problem and did not loan enough extension cords from Nanyang House. This resulted in the purchase of extension cords from nearby supermarkets and hardware shops. Cloth tapes were also used in large quantities to tape down the exposed wiring on the floor. A staple gun was also purchased to maintain the skirting on the tables provided by the contractors.

3. Other problems.

During the morning the booths were directly facing the sun, causing discomfort to the participants. However the situation eased by noon.

Post SI 2006

1. Liaison with contractors for the tearing down of event area.

The night the event ended, all contractor-installed items were to be removed.

2. Transport of loan and logistical items back to NTU.

This was done on the night the event ended and was completed on the day during office hours. Truck was also returned the day after the event.

Personal Learning Points

1. Planning

Although the planning could be better contrived, however even the best plans could be laid to ruins. It will all depend on the response to the particular crisis that threatens the running of the event. The response needed is initiated by experience, something that this department clearly lacks. However, there was help from all other departments and this proved to be the force that drove the event along. Each department and EviroFest committee members were driven and united to ensure that this event proceeds.

2. Listen

All humans like to express their views, however for this sort of event there is also a need to listen. To listen to the views of the more experienced, to listen to the views of the organizing committee, to listen to the feedback from the participants.

Suggestions

1. Have a definite chain of command.

A definite chain of command is required. All committee members have their own views on the way things are to be run. However, this will lead to chaos as all members go their separate ways, as witnessed during briefing day. However all this could be solved if there is a person that will make the final decision. This person is to be the most experienced or the highest ranking.

2. Do not be afraid to make mistakes.

In organizing events on such a scale, mistakes are inevitable. Do not be afraid to make them as this will lead to learning and the prevention of future mistakes. Mistakes made also should be raised up immediately to the main committee so that actions could be taken to reduce the impact.