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PubMed2005

Small-world properties emerge in highly compartmentalized networks with intermediate group sizes and numbers.

Many recent studies have focused on two statistical properties observed in diverse real-world networks: the small-world property and compartmentalization [D. J. Watts and S. H. Strogatz, Nature 393, 440 (1998); M. Girvan and M. E. J. Newman, Proc. Natl. Acad. Sci. 99, 7821 (2002)]. Models that include group affiliations have been shown to produce networks with high clustering coefficients, a necessary condition for small-world properties [M. E. J. Newman, Phys. Rev. E, 68, 026121 (2003); M. E. J. Newman and J. Park, Phys. Rev. E 68, 036122 (2003)]. However, the consequences of varying the number and size of groups in a network are not well understood. In order to investigate the consequences of group organization, we examined sets of networks that varied simultaneously in the size and number of groups, while maintaining the same overall size and average degree. Here we show that the small-world property arises in maximally compartmentalized and clustered networks that occur in the intermediate region between few, very large groups and many, very small groups.

Journal Article↗
PubMed2002

Synchronization in small-world systems.

We quantify the dynamical implications of the small-world phenomenon by considering the generic synchronization of oscillator networks of arbitrary topology. The linear stability of the synchronous state is linked to an algebraic condition of the Laplacian matrix of the network. Through numerics and analysis, we show how the addition of random shortcuts translates into improved network synchronizability. Applied to networks of low redundancy, the small-world route produces synchronizability more efficiently than standard deterministic graphs, purely random graphs, and ideal constructive schemes. However, the small-world property does not guarantee synchronizability: the synchronization threshold lies within the boundaries, but linked to the end of the small-world region.

Models, Theoretical↗
PubMed2001

Developing drugs for the developing world: an economic, legal, moral, and political dilemma.

This paper discusses the economic, legal, moral, and political difficulties in developing drugs for the developing world. It argues that large, global pharmaceutical companies have social responsibilities to the developing world, and that they may exercise these responsibilities by investing in research and development related to diseases that affect developing nations, offering discounts on drug prices, and initiating drug giveaways. However, these social responsibilities are not absolute requirements and may be balanced against other obligations and commitments in light of economic, social, legal, political, and other conditions. How a company decides to exercise its social responsibilities to the developing world depends on (1) the prospects for a reasonable profit and (2) the prospects for a productive business environment. Developing nations can either help or hinder the pharmaceutical industry's efforts to exercise social responsibility through various policies and practices. To insure that companies can make a reasonable profit, developing nations should honor pharmaceutical product patents and adhere to international intellectual property treaties, such as the Trade-Related Aspects of Intellectual Property Rights (TRIPS) agreement. To insure the companies have a good business environment, developing nations should try to promote the rule of law, ethical business practices, stable currencies, reliable banking systems, free and open markets, democracy, and other conditions conducive to business. Overall, this paper advocates for reciprocity and cooperation between pharmaceutical companies and developing nations to address the problem of developing drugs for the developing world. In pursuing this cooperative approach, developing nations may use a variety of other techniques to encourage pharmaceutical companies to act responsibly, such as subsidizing pharmaceutical research, helping to design and implement research protocols, providing a guaranteed market, and bulk buying.

Beneficence↗
PubMed2004

A prospective investigation of the relationship between just-world beliefs and the desire for revenge after September 11, 2001.

We prospectively examined the relationship between individuals' belief in a just world and their desire for revenge against the perpetrators of the September 11 terrorist attacks against the United States. Eighty-three undergraduate students who had completed a measure of just-world beliefs prior to the terrorist attacks were assessed approximately 2 months following the attacks. The more strongly they had endorsed just-world beliefs prior to the attacks, the more distressed they felt about the attacks and the more they desired revenge. Furthermore, the relationship between belief in a just world and the desire for revenge was mediated by feelings of distress in response to the terrorist attacks. The results point to the importance of justice beliefs in understanding responses to the terrorist attacks.

Adult↗
PubMed2006

An approach to the management of leukemia in the developing world.

Management of leukemia is expensive. In the developing world where there are significant resource constraints, how does the physician manage leukemia? Government health budgets need to put their money into areas where a small investment is likely to benefit a large proportion of its people and these would include immunization, sanitation, family planning and treatment of communicable diseases and the cost of expensive treatments would have to be borne by the patient and family. However, in many of the emerging economies in the developing world, society is three-tiered in terms of resources with a small proportion being able to afford the best treatment, the middle class with the ability to meet a significant proportion of the healthcare costs on their own and the poor who depend wholly on what the Government health budget can afford. Providing an accurate diagnosis is possible even with limited resources and this must be made available to all. Sometimes a precise diagnosis even at the molecular level is more important in the developing world so that resources are not wasted on inappropriate treatments. Choosing a protocol for management based on resources available for the individual patient would appear ethically unacceptable, but is probably the only solution when wealth is unevenly distributed in society. This paper illustrates an approach to the management of leukemia in the developing world that has evolved with experience over two decades in a tertiary referral hospital in India.

Antineoplastic Protocols↗
PubMed2004

Haemophilia in the developing world: successes, frustrations and opportunities.

There is a need to bridge key gaps between high- and low-income countries and individuals; between health policy and clinical practice; and between producers and users of healthcare technology and scientific evidence. The objective of this report was to perform a diagnosis of the situation in the developing world through a survey. This survey was conducted to gather specific information on various aspects related to haemophilia. Countries were chosen by their comparability in infant and adult mortality rates according to the regionalization proposed by the World Health Organization. These indicators are very sensitive to socioeconomic conditions, and have been widely used to study health inequalities. All regions, except Africa and the East Mediterranean, were represented. Africa was excluded because its indicators were not comparable. The East Mediterranean was not represented because of difficulties in contacting investigators. Twenty-one country representatives were contacted, and 11 answered the questionnaire. Successes obtained by developing countries are based more on the skills and creativity of the local professionals than on the availability of state-of-the-art technology. Frustrations were related to disease underregistration and the limited availability of treatment products. Haemophilia care in the developing world is not as fair as we would like it to be. Governments do not always cover treatment costs, and a very small percentage of the national health budgets is allotted to haemophilia care. The role of the World Federation of Hemophilia was considered crucial by all the investigators surveyed. Training programmes and supply of factor concentrates were the main contributions identified by the respondents.

Adult↗
PubMed2005

Preventive strategies of renal failure in the Arab world.

The prevalence of both acute and chronic renal failure is high in the Arab world. Data available on the exact prevalence of various renal diseases are very limited. Nevertheless, the reported prevalence of chronic renal failure is 80 to 120 per million population (pmp) in the Kingdom of Saudi Arabia and 225 pmp in Egypt. This is in comparison with the reported prevalence of 283 pmp in Europe, 975 pmp in the United States, and 1149 pmp in Japan. Lower prevalence rates reported in this region could be due to underreporting. The economic burden of renal replacement on health care providers is enormous. In the Kingdom of Saudi Arabia, the estimated cost per annum incurred toward maintenance hemodialysis is US 19,400 US dollars and, considering that there are more than 7200 patients on regular dialysis in this country, the total expenditure is enormous. Such large amounts may be beyond the monetary capacity of many countries in this region because of limited financial resources. These figures clearly suggest that there is an urgent need to establish a massive prevention program. The strategy adapted should be innovative and imaginative and should be one that is maximally cost effective. Paradoxically, in the Arab world, we have a good opportunity to reduce the incidence of kidney failure (chronic and acute) substantially by appropriately chosen models. This is because many of the causes of renal failure are eminently preventable. In fact, a rough estimate is that these programs, if successful, can reduce the incidence by as much as 40% (personal communication, Shaheen, 2003). It is worthy of mention that, in the Arab world, the budget for research is about 0.15% of the national domestic product compared with the international average of 1.5%. In this article, we concentrate on some of the main causes of renal failure in the Arab world that we feel can be prevented and suggest ways that can best address this issue.

Acute Kidney Injury↗
PubMed2005

Electronic strategies for information and research: cyberNephrology/cyberMedicine in the emerging world.

Communication and medicine have evolved together. Internet resources now provide an unprecedented opportunity to provide health assistance to the developing world. The International Society of Nephrology Informatics Commission and National Kidney Foundation cyberNephrology initiative (http://www.cybernephrology.org) have created e-mail discussion groups (e.g., NEPHROL, NEPHKIDS, and so forth) and online texts and web resources (e.g., the Schrier Atlas: http://www.kidneyatlas.org) that are, in many respects, ahead of other areas of medicine. On the other hand, nephrology is quite behind in its embrace of some specific communications initiatives that could benefit emerging nations: the Health InterNetwork Access to Research Initiative program, which provides free full-text access to medical journals and books in poorer countries; the Global Health Network Supercourse, which provides specially designed online lectures for the developing world; and Internet2/Abilene and similar research networks around the world, which provide reliable, guaranteed bandwidth for high-quality Internet videoconferencing as an alternative to face-to-face lectures and meetings. The intent of many educational ventures in nephrology, particularly in the clinical practice guideline realm (National Kidney Foundation Kidney Disease Outcomes Quality Initiative, Kidney Disease Improving Global Outcomes, and so forth), is not just to disseminate information but to change human behavior: physician practice and referral patterns, patient compliance, and so forth. Concepts from the worlds of marketing and entertainment, where the science of changing human behavior is highly evolved, can be used to create high-impact, educational offerings to promote health. They can also be highly beneficial to share Internet educational innovations and future vision across boundaries of medical specialties, which is part of the intent of the cyberMedicine joint venture (http://www.cyber-medicine.org).

Humans↗
PubMed1996

A Survey of Travel Clinics Throughout the World.

Background: The growth of travel medicine as a specialty has been marked by a dramatic increase in the number of travel clinics worldwide. A survey was conducted of travel clinics to assess the current practice of travel medicine. Methods: A questionnaire was sent to members of the International Society of Travel Medicine, asking questions about clinic demographics, categories of advice given and immunizations available, and educational training of clinic personnel. Results: Responses from 341 clinics were analyzed; 57% were located in the United States; 21% in Europe; 6% in the United Kingdom or Ireland; 6% in Canada; and 11% from other areas of the world. Most clinics were private (41%); however, many other affiliations were represented, including schools of medicine (20%), hospitals (10%), and occupational medicine and student health practices (10%). The median number of patients seen per year was 750; however, the range was 6 to 50,000. Each clinic offered many vaccines, and advice for the prevention of malaria, diarrhea, and insect avoidance was given over 95% of the time. Providers of advice were nurses (57% of the time) and physicians (83%); however, in the United States nurses gave advice independently more frequently (22% vs. 8%, p <.001) than in other parts of the world. Clinics also frequently gave telephone advice (15% charged for this service) and evaluated ill returned travelers. Over 60% of physicians had trained in infectious diseases and/or tropical medicine, although there were training differences between regions of the world. Conclusions: Travel clinics throughout the world demonstrate similarities as well as differences in practice. Defining these will help in determining practice needs in the growing field of travel medicine.

Journal Article↗
PubMed1994

Isolation and characterization of simian T-cell leukemia virus type II from New World monkeys.

Since the description of human T-cell leukemia virus type I (HTLV-I) and its simian counterpart, simian T-cell leukemia virus type I (STLV-I), the possible existence of other related simian retroviruses has been raised. Here, we report a new retrovirus, STLV-II, which we have identified in spider monkeys (Ateles fusciceps), a New World primate species. Initially, a recombinant HTLV-II envelope protein (RP-IIB) was used to identify anti-STLV-II antibodies in New World monkeys by Western blot (immunoblot) assays. Subsequently, the virus was characterized by Southern blot hybridization, which showed that STLV-II and HTLV-II have a high degree of nucleotide sequence homology but have different restriction enzyme patterns. Nucleotide sequence analysis of the pX-II region of STLV-II provirus revealed 3% variation with the corresponding region of HTLV-II. Electron micrographic studies revealed HTLV-like, type C retrovirus particles outside the cell membranes of STLV-II-infected cells. This study describes the first link between HTLV-II and a simian reservoir in the New World. Further molecular studies of STLV-II infection in different species of New World monkeys, especially from the wild, may provide valuable information about the origin and intragroup relationships of South American monkeys. Spider monkeys infected with STLV-II may serve as an important animal model for HTLV-II infection in humans.

Animals↗
PubMed2003

Novel gamma-1 herpesviruses identified in free-ranging new world monkeys (golden-handed tamarin [Saguinus midas], squirrel monkey [Saimiri sciureus], and white-faced saki [Pithecia pithecia]) in French Guiana.

The recent finding of a novel Epstein-Barr virus-related lymphocryptovirus (CalHV-3) in a captive colony of common marmoset (Callithrix jacchus) in the United States modifies the view that the host range of lymphocryptovirus is restricted to humans and Old World primates. We investigated the presence of Epstein-Barr virus-related viruses in 79 samples of New World monkeys caught in the wild, including six species of the Cebidae family and one of the Callitrichidae, living in the rain forest of French Guiana. Using a degenerate consensus PCR method for the herpesvirus DNA polymerase gene, we identified three novel lymphocryptoviruses from golden-handed tamarin (Saguinus midas) of the Callitrichidae family and squirrel monkey (Saimiri sciureus) and white-faced saki (Pithecia pithecia) of the Cebidae family. With the CalHV-3 strain, these three novel viruses constitute a well-supported phylogenetic clade in the Lymphocryptovirus genus, which is clearly distinct from the lineage of Old World lymphocryptovirus, hosted by catarrhine monkeys and humans. In tamarins, the prevalence of the novel lymphocryptovirus was more than 50%, indicating that it circulates well in the wild population, perhaps due to specific ecoethological patterns such as confrontations and intergroup migration. The detection and partial molecular characterization of the polymerase gene of three novel Gamma-1-Herpesvirinae from New World monkeys caught in the wild clearly indicate that free-ranging populations of platyrrhine are natural hosts of lymphocryptoviruses. Further characterization of these novel viruses will provide new insight not only into the origin and evolution of Gammaherpesvirinae but also into their pathogenicity.

Animals↗
PubMed2006

Expression profiles of endogenous retroviruses in Old World monkeys.

Human endogenous retroviruses (HERVs) are a major component of the human genome and an active part of the transcriptome. Some HERVs play vital biological roles, while others potentially contribute to diseases. Many HERVs are relatively new in the primate genome, having entered or expanded after the lineages leading to the platyrrhines (New World monkeys) and catarrhines (Old World monkeys and apes) separated. Most HERVs are active in at least some tissues, though tissue specificity is common for most elements. We analyzed multiple tissues from several Old World monkeys using retroviral pol-based DNA microarrays and quantitative PCR methods to determine their ERV expression profiles. The results demonstrate that while many ERVs are active in nonhuman primates, overall the tissue expression specificity is unique to each species. Most striking is that while the majority of HERVs analyzed in this study are expressed in human brain, almost none are expressed in Old World monkey brains or are only weakly expressed.

Animals↗
PubMed2005

Improving drug use for children in the developing world.

Children differ significantly from adults in the way they absorb, metabolise, and excrete drugs. These parameters also vary as children grow from neonates through to adolescence. The practical implications and challenges that this presents are well know to anyone who is involved in the medical management of sick children. The importance of paediatric medication safety and efficacy has been gaining increasing attention in the developed world over the past decade. The United States has introduced a carrot and stick approach to increase research into medications for children with the "paediatric exclusivity provision" and the "paediatric rule". The European Union is also investigating ways of improving the availability of medications for children. Unfortunately, this increased focus on appropriate medicines for children, which has occurred in the developed world, has not been mirrored in developing nations. Currently more than 10 million children under the age of 5 years die each year, with only six countries accounting for 50% of these deaths. The majority of these deaths are from treatable or preventable diseases. The developed world has a moral and ethical obligation to share its gains with the children of the world.

Adolescent↗
PubMed2003

Tobacco industry strategies to undermine the 8th World Conference on Tobacco or Health.

OBJECTIVE: To demonstrate that Philip Morris and British American Tobacco Company attempted to initiate a wide ranging campaign to undermine the success of the 8th World Conference on Tobacco or Health held in Buenos Aires, Argentina, in 1992. DATA SOURCES: Publicly available tobacco industry documents housed in Minneapolis, Minnesota, USA; Guilford, UK; on-line document websites; and telephone interviews with informed parties. STUDY SELECTION: Those documents determined to be relevant to the companies' campaigns against the 8th World Conference on Tobacco or Health. DATA EXTRACTION: Revision of chapter VIII of the July 2000 WHO report by a committee of experts, entitled: Tobacco company strategies to undermine tobacco control activities at the World Health Organization: report of the committee of experts on tobacco industry documents. DATA SYNTHESIS: Internal documents describe proposed media and science orientated campaigns developed by BAT, Philip Morris, and their consultants to divert attention away from the conference. RESULTS AND CONCLUSION: This work shows that the tobacco industry has the resources and vested interest to combat perceived threats in its regional operating markets, in this case its Latin American market. It is important for the worldwide public heath community to become aware of the numerous ways in which the tobacco industry and its front groups can work against international tobacco control meetings, even including the manipulation of or working with other public health groups to oppose tobacco control efforts. Future world conference planners and participants should be aware that the tobacco industry is likely to continue to employ such methodology. There is no reason to think that the industry is paying less attention to such conferences in the present or future. Rather, it is likely the industry will adopt and expand strategies that were successful while abandoning those that were not effective. Required disclosure of financial support by all participants at all tobacco scientific conferences is recommended. For the tobacco control community, we also recommend careful coalition building and networking with other public health groups on the ways tobacco is implicated in other public health issues.

Congresses as Topic↗
PubMed2003

Spatial memory following shifts of gaze. I. Saccades to memorized world-fixed and gaze-fixed targets.

During a shift of gaze, an object can move along with gaze or stay fixed in the world. To examine the effect of an object's reference frame on spatial working memory, we trained monkeys to memorize locations of visual stimuli as either fixed in the world or fixed to gaze. Each trial consisted of an initial reference frame instruction, followed by a peripheral visual flash, a memory-period gaze shift, and finally a memory-guided saccade to the location consistent with the instructed reference frame. The memory-period gaze shift was either rapid (a saccade) or slow (smooth pursuit or whole body rotation). This design allowed a comparison of memory-guided saccade performance under various conditions. Our data indicate that after a rotation or smooth-pursuit eye movement, saccades to memorized world-fixed targets are more variable than saccades to memorized gaze-fixed targets. In contrast, memory-guided saccades to world- and gaze-fixed targets are equally variable following a visually guided saccade. Across all conditions, accuracy, latency, and main sequence characteristics of memory-guided saccades are not influenced by the target's reference frame. Memory-guided saccades are, however, more accurate after fast compared with slow gaze shifts. These results are most consistent with an eye-centered representational system for storing the spatial locations of memorized objects but suggest that the visual system may engage different mechanisms to update the stored signal depending on how gaze is shifted.

Animals↗
PubMed2000

Treatment of Old World cutaneous leishmaniasis by pentamidine isethionate. An open study of 11 patients.

BACKGROUND: Pentavalent antimonial derivatives (PAD), especially meglumine antimoniate (Glucantime((R))), are usually considered as the first-line drugs for Old World leishmaniasis, but their potential toxicity and the number of required injection, either intralesional or intramuscular, prompt to search for alternative treatments. OBJECTIVE: To evaluate the efficiency and tolerance of pentamidine isethionate in Old World leishmaniasis. METHODS: An open pilot study included 11 patients from two regional academic centers, with varied parasitological forms of Old World leishmaniasis, treated with three strictly intramuscular injections of 4 mg/kg of base-pentamidine every other day. RESULTS: Tolerance was good overall, and 8/11 (73%) of patients responded well with a quick healing of their lesions, little scarring and no relapse. CONCLUSION: Pentamidine isethionate is a safe and effective first-line treatment for Old World leishmaniasis. Larger-scale prospective studies comparing several dosage regimens of pentamidine and pentamidine isethionate to PAD are warranted.

Adolescent↗
PubMed1993

Colour vision in New World monkeys and the single-locus X-chromosome theory.

The single-locus X-chromosome theory was proposed to explain the unique intra- and inter-species variation in the colour vision found in New World monkeys. The colour vision of only five species of these monkeys has been studied in any detail, and although this data does show some minor deviations from the theory, it is generally consistent with the theory. It has been suggested that the colour vision of New World monkeys may represent an intermediate stage in between the dichromatic colour vision of non-primate mammals and the uniform trichromacy of Old World primates. Alternatively, the colour vision system of New World monkeys may represent a method of obtaining the maximum variation in the colour vision of closely related family groups.

Animals↗
PubMed1991

Endogenous blockade of 1,25-dihydroxyvitamin D-receptor binding in New World primate cells.

When assessed by 1,25-dihydroxyvitamin D3 (1,25(OH)2-D3)-receptor (VDR) binding analysis or 1,25(OH)2-D3-VDR-directed bioresponsiveness, cultured cells from some New World primates (platyrrhines) demonstrate a variable decrement in VDR when compared with Old World primate (catarrhine) cells. To study this difference in VDR expression among primates, we performed immunoblot analysis of the VDR in cultured dermal fibroblasts from platyrrhines in the genera Pithecia and Aotus and from catarrhines in the genus Presbytis; although a platyrrhine, the owl monkey (Aotus) expresses a VDR of the catarrhine (wild type) phenotype. Despite a 10-fold difference in the content of VDR by ligand binding analysis among cells from the three prototypic primate genera, there was a less than or equal to 10% difference in the steady-state level of 50-kD VDR detected by immunoblot analysis of cellular extracts. We investigated this apparent discrepancy in the content of VDR in immunoblots and ligand binding analyses by mixing VDR-containing nuclear extracts of equivalent protein concentration from the various primates. Coincubation of Pithecia and Aotus fibroblast extracts with Presbytis extract diminished specific 1,25(OH)2-D3 binding in the mix by 90% and 95% respectively. Similar results were obtained by mixing nuclear extracts of the owl monkey cell line, OMK, and the vitamin D resistant marmoset B-lymphoblast cell line B95-8. A wild type 1,25(OH)2-D3-binding profile was restored in mixtures after trypsin or heat treatment of the B95-8 extract. These data indicate that some New World primate cells contain a soluble protein that prevents intracellular 1,25(OH)2-D3-VDR binding. It is possible that the quantitative differences in the expression of this protein are responsible for 1,25(OH)2-D3 and other steroid hormone resistant states of variable severity in New World primates.

Animals↗