Convection and permeation and albumin between plasma and interstitium.

Nonequilibrium thermodynamics is combined with compartmental analysis to interpret albumin sieving and tracer experiments in terms of a permeability-surface product PS (permeation) and a solvent drag reflection coefficient σ_f (convection) for various blood-tissue barriers. The human whole-body albumin data of Lassen, Parving, and Rossing (Lassen, Parving, and Rossing, Microvasc. Res.7, i–iv (1974)), modified for nonliver tissues by Johnson and Levitt (Johnson &; Levitt, Microvasc. Res.9, 141 (1975)) lead to P ～ 1.8 × 10^?8 cm sec^?1 (based on a surface area per unit plasma volume of 700 cm^?1) and to σ_f ～ 0.9, which imply, in agreement with Johnson and Levitt, that permeation is the dominant nonliver blood-tissue transport mechanism for albumin in the normal resting human. Similar values are derived from the dog paw muscle data of Garlick and Renkin (Garlick and Renkin, Amer. J. Physiol.219, 1595–1605 (1970)). The Casley-Smith (Casley-Smith, Microvasc. Res.9, 43–48 (1975)) mechanism of uphill albumin transport is verified as possible. It is tentatively inferred that lymph formation in resting tissue does not result from a small difference between a large fluid (volumetric) filtration and an almost equally large fluid reabsorption, either in the same capillary (Starling) or between different capillaries (Zweifach) (Zweifach, Circ. Res.34, 858–866 (1974)). Rather, reabsorption is negligibly small relative to filtration, and lymph flow is comparable to volumetric filtration.     

ERCP and MRCP--when and why

Since the introduction of endoscopic retrograde cholangiopancreatography (ERCP) in the 1970s, gastroenterologists have a wide spectrum of diagnostic and therapeutic options in the biliopancreatic ductal system at their disposal. With its arrival in the 1990s, magnetic resonance cholangiopancreatography (MRCP) developed as a potent diagnostic tool in biliopancreatic pathology. Currently, MRCP is widely replacing diagnostic ERCP and thereby avoiding complications related to endoscopic technique.We summarize evidence-based data and demonstrate indications and differential indications for MRCP and ERCP in pancreatic disease. Complications related to the procedures and possible medical prevention are discussed. The feasibility of interventional endoscopy in pancreatic disease is reported in detail. The role of gastroenterologists in performing MRCP is outlined on the basis of practical examples.     

Micronutrients and infection: interactions and implications with enteric and other infections and future priorities

Symposium presentations have focused on the elegant molecular science and the biologic mechanisms by which micronutrients play critical roles in cellular and humoral immune responses, cellular signaling and function, and even in the evolution of microbial virulence. The concluding session examined the practical issues of how best to evaluate the nutritionally at-risk host, especially in the areas of greatest need-an analytical model of nutrient-immune interactions, implications of nutritional modulation of the immune response for disease, and the implications for international research and child health. This overview illustrated how malnutrition may be a major consequence of early childhood diarrhea and enteric infections, as enteric infections may critically impair intestinal absorptive function with potential long-term consequences for growth and development. The potentially huge, largely undefined DALY (disability-adjusted life years) impact of early childhood diarrheal illnesses demonstrates the importance of quantifying the long-term functional impact of largely preventable nutritional and infectious diseases, especially in children in developing areas.     

Leptin and cellular and innate immunity in abstinent alcoholics and controls

BACKGROUND: Basic studies indicate that in vitro and in vivo doses of leptin modulate cellular immune responses. Given evidence that concentrations of leptin are altered in alcoholics who also show immune abnormalities, this study examined the relationships between circulating levels of leptin and markers of cellular and innate immunity. METHODS: Circulating levels of leptin, natural killer cell (NK) activity, interleukin-2 (IL-2)-stimulated NK activity, and concanavalin A-stimulated production of IL-2, IL-6, IL-10, and IL-12 were compared between abstinent DSM-IV alcohol-dependent men (n = 27) and age- and gender-matched controls (n = 34). RESULTS: As compared with controls, alcoholics showed lower NK activity (p < 0.01) and a trend for lower levels of leptin (p = 0.055). In the total sample, leptin predicted NK activity (beta = 0.33; p < 0.05) after controlling for the confounding influence of body mass index, alcohol intake, and smoking. Leptin was not correlated with any of the cytokine measures. To examine whether the effects of leptin were mediated by its direct action on NK, additional studies examined in vitro effects of leptin on NK activity in healthy volunteers (n = 10); leptin doses (0.1, 1, and 10 nM) yielded levels of NK activity comparable to those with media alone. CONCLUSIONS: These data show that circulating levels of leptin are associated with NK activity in humans and suggest that abnormal in vivo concentrations of leptin may contribute to the declines of NK activity in alcoholics who are at risk for infectious diseases.     

Sex and Gender and Allostatic Mechanisms of Cardiovascular Risk and Disease

Cardiovascular diseases are leading causes of mortality and morbidity in adults worldwide. Multiple studies suggest that there are clinically relevant sex differences in cardiovascular disease. Women and men differ substantially in terms of prevalence, presentation, management, and outcomes of cardiovascular disease. To date, however, little is known about why cardiovascular disease affects women and men differently. Because many studies do not differentiate the concept of sex and gender, it is sometimes difficult to discriminate sociocultural vs biological contributors that drive observed clinical differences. Female sex has some biological advantages in relation to cardiovascular disease, but many of these advantages seem to disappear as soon as women develop cardiovascular risk factors (eg, type 2 diabetes, hypertension, dyslipidemia). Furthermore, stress and allostatic load could play an important role in the relationship between sex/gender and cardiovascular diseases. In this narrative review, we argue that chronic stress and psychosocial factors might better encompass the patterns of allostatic load increases seen in women, while biological risk factors and unhealthy behaviours might be more important mechanisms that drive increased allostatic load in men. Indeed, men show allostatic load patterns that are more associated with impaired anthropometric, metabolic, and cardiovascular functioning and women have greater dysregulation in neuroendocrine and immune functioning. Thus gender-related factors might contribute to the pathogenesis of cardiovascular disease especially through stress mechanisms. It is important to continue to study the mechanisms by which gender influences chronic stress, because chronic stress could influence modifiable gendered factors to promote cardiovascular disease prevention.     

Medical and Psychology Students' Knowledge and Attitudes Regarding Aging and Sexuality

The current study surveys medical and doctoral psychology students (N = 100) from an urban northeastern university regarding knowledge and attitudes toward elderly sexuality and aging using the Facts on Aging Quiz, the Aging Sexuality Knowledge and Attitudes Scale, and measures of interest in gerontology, academic/clinical exposure to aging and sexuality, and contact with elders. The current study found that psychology students demonstrated greater aging knowledge than medical students; however, both groups showed gaps in knowledge about sexuality. Married students had greater academic/clinical exposure and greater knowledge about aging but less permissive attitudes toward elderly sexuality. Generally, knowledge about aging was the strongest correlate of knowledge about sexuality. Level of knowledge about sexuality was not associated with attitudes. Attitudes toward sexuality and aging may be more strongly tied to demographic variables reflective of religious beliefs or adherence to sociocultural norms.     

Diabetes and Clinical and Subclinical CVD

Diabetes mellitus is a major cardiovascular risk factor and its prevalence has been increasing globally. This review examines the contributions of the MESA (Multi-Ethnic Study of Atherosclerosis), a diverse American cohort (6,814 adults ages 45 to 84, recruited from 2000 to 2002, 50% female, 62% nonwhite) toward understanding the relationship between diabetes and clinical and subclinical cardiovascular disease. People with diabetes have a high burden of subclinical vascular disease as measured by coronary artery calcification (CAC), carotid artery intima-media thickness, valvular calcification, and alterations in left ventricular structure. CAC substantially improves cardiovascular risk prediction. Among adults with diabetes, 63% had CAC >0; above CAC >400 Agatston units the event rate was 4% annually, whereas an absence of CAC was a marker of a very low cardiovascular disease rate (0.4% to 0.1% annually). These stark differences in rates may have implications for screening and/or targeted prevention efforts based on CAC burden. MESA has also provided insight on diabetes epidemiology.     

Renal markers and predictors, and renal and cardiovascular risk factors

An important task of the nephrologists during the last century, it has been the search of elements and means that allow us, with the adequate precision, to correlate the functional deterioration of the kidney, and the patient's clinical reality. And the continuous searching of factors and markers that injure them, the prognosis, and early diagnosis, to be able to predict the degree of the organs and patient's survival. Almost parallel survival presage in the natural history of the illness, almost one century ago. In the second half of the XX century, in the developed countries, appear modifications of the social, cultural, and sanitary conditions, that make appear some very different partner-sanitary and epidemic circumstances, and take place like they are, among others: 1. An increase of per cápita private rents, what takes place to increase of the level of social life and the population's health. With increment of the longevity, and smaller incidence and prevalence of classic process, as malnutrition, infections, infantile mortality, so increasing the weight of the cardiovascular diseases and death. This is potentiated for the increment and the incidence of environmental cardiovascular risk's factors (like high caloric and fatty-rich diets, smoke, alcohol, disappearance of the physical work, inactivity, etc). And that situations are also product of the change of the outline of human and social values and guides. 2. Access of the whole population to a sanitary attention of more quality and effectiveness. It allows the biggest survival of patients that suffer vascular crisis, (as angina, miocardial infarction or cerebrovascular accident), that few years ago they have had a higher morbimortality and an inferior survival (2). 3. The execution of big epidemic studies has been able to, not only characterize and test with scientific evidence to numerous factors and markers, that induce renal and cardiovascular prejudicial changes, but risk and death probability prediction. And also, its possible association nexuses, its injuring mechanisms, and the characterization of the new "emergent" renal and cardiovascular risk's markers and factors. 4. The impact on the possibility to treat the end stage renal disease with effective and prolonged procedures, by hemodialisis or kidney transplantation, has been occurred. The affected population's survival with the adequacy renal-sustitution treatment, and the possibility of indefinite duration of its treatment, has also impacted on the public health, and its resources, in an evident way. Simultaneously to increase of the incidence in the population, the electivity for the treatment has been enlarged and extended increasing it exponentially. These facts are documented here, and are defined the characteristics of the factors and markers of risk, of renal and cardiovascular diseases. The defined factors are valued to mark, so far as with the well-known evidence is possible, the prediction and the progression of the renal and cardiovascular functional deterioration: The hypertension, cardiovascular remodeling, the arterial stiffness, the heart rate, the sympathetic activation, the modification of the physiological response of the target organ to the overcharge, the metabolic syndrome, the obesity, the insulin resistance, the altered lipid profile, and metabolism of the fatty acids, the salt-sensibility, the decrease of the renal functional reserve, the glomerular hyperfiltration, the absence of the arterial pressure nocturnal descent, the abnormal excretion of proteins for the urine, the phenomenon induced by dysfunctions of the clotting, superoxide production, growth factors, the production of chronic inflammation and its markers, the factors of the glomerulosclerosis progression, the hyperuricemic status, the endothelial dysfunction and others, are evaluated. As well as their association among them and with other factors of risk not changeable like the age, and in turn, with other acquired voluntarily factors of risk, as the smoking habit and the alcohol. These facts are now impacting on the population's sanity. And also in the professional nephrologic exercise, so much for the cardiovascular and renal morbimortality increased, as for the increase of the incidence of end-stage renal disease susceptible to treat with of substitutive procedures. They try to justify the sentence of Alan Weder of the heading, and other concepts like "epidemic factors of the XXI century", and intuitive expressions like "predialitic endothelial disruption or ruin".     

Urbanization and tropical health--then and now

Since the launch of the Annals of Tropical Medicine and Parasitology 100 years ago, the percentage of the world's population living in urban settings has more than tripled and is now approaching 50%. Urbanization will continue at a high pace, particularly in the less developed regions of Africa and Asia. The profound demographic, ecological and socio-economic transformations that accompany the process of urbanization have important impacts on health and well-being. In industrialized countries, urbanization led to the so-called 'epidemiological transition', from acute infectious and deficiency diseases to chronic non-communicable diseases, many decades ago. In the developing world, surprisingly little research has been carried out on the health-related aspects of urbanization. In a temporal analysis of publications in the Annals of Tropical Medicine and Parasitology, for example, in which the first volume in every decade from 1907 was examined, only 16 (2.6%) of the 604 articles investigated focused on epidemiological and/or public-health issues in urban tropical settings. This review begins with the question 'what is urban?' and then provides a summary of the trends seen in urbanization, and its impacts on human health, over the past century, on both a global and regional scale. For the main tropical diseases, estimates of the at-risk populations and the numbers of cases are updated and then split into urban and non-urban categories. The inhabitants of urban slums are particularly vulnerable to many of these diseases and require special attention if internationally-set targets for development are to be met. Heterogeneity, a major feature of urban settings in the tropics that complicates all efforts at health improvement, is demonstrated in an exploration of a densely populated municipality of a large West African town. Urban planners, public-health experts and other relevant stakeholders clearly need to make much more progress in alleviating poverty and enhancing the health and well-being of urban residents, in an equity-effective and sustainable manner.