Beneficial effects of potassium on human health

Until recently, humans consumed a diet high in potassium. However, with the increasing consumption of processed food, which has potassium removed, combined with a reduction in the consumption of fruits and vegetables, there has been a large decrease in potassium intake which now, in most developed countries, averages around 70 mmol day⁻¹, i.e. only one third of our evolutionary intake. Much evidence shows that increasing potassium intake has beneficial effects on human health. Epidemiological and clinical studies show that a high-potassium diet lowers blood pressure in individuals with both raised blood pressure and average population blood pressure. Prospective cohort studies and outcome trials show that increasing potassium intake reduces cardiovascular disease mortality. This is mainly attributable to the blood pressure-lowering effect and may also be partially because of the direct effects of potassium on the cardiovascular system. A high-potassium diet may also prevent or at least slow the progression of renal disease. An increased potassium intake lowers urinary calcium excretion and plays an important role in the management of hypercalciuria and kidney stones and is likely to decrease the risk of osteoporosis. Low serum potassium is strongly related to glucose intolerance, and increasing potassium intake may prevent the development of diabetes that occurs with prolonged treatment with thiazide diuretics. Reduced serum potassium increases the risk of lethal ventricular arrhythmias in patients with ischaemic heart disease, heart failure and left ventricular hypertrophy, and increasing potassium intake may prevent this. The best way to increase potassium intake is to increase the consumption of fruits and vegetables.     

Inflammation and conjugated linoleic acid: mechanisms of action and implications for human health

Data from a number of studies and trials have shown that different conjugated linoleic acids (CLA's) may produce beneficial effects on cancer, atherosclerosis, hypertension, diabetes and changes in body composition. Despite the increasing knowledge about CLA's implications on health, the mechanism of action of these fatty acids is not completely understood. Moreover, human studies indicate that some of these beneficial effects are considerably less evident than anticipated from mice studies, while the efficacy and safety of dietary supplements containing CLA have been questioned in some intervention trials. Recently, it has been suggested that the anti-carcinogenic and anti-atherosclerosis effects of CLA's stem from its anti-inflammatory properties. Because inflammatory responses are associated with the pathophysiology of many diseases, including obesity and the metabolic syndrome, the investigation in this area is of growing interest in recent years.     

Molecular and genetic mechanisms of obesity: implications for future management

Obesity has become a worldwide public health problem affecting millions of people. A disruption of the balance between energy intake and energy expenditure is believed to be the major cause of obesity. Substantial progress has been made in deciphering the pathogenesis of energy homeostasis over the past few years. The fact that obesity is under strong genetic control has been well established. Human monogenic obesity is rare in large populations, the most common form of obesity is considered to be a polygenic disorder arising from the interaction of multiple genetic and environmental factors. Here, we attempt to briefly review the most recent understanding of molecular mechanisms involved in energy homeostasis and adipogenesis. We discuss the advantages and disadvantages of various approaches commonly used in search for susceptibility genes for obesity. The main results from these genetic studies are summarized, with comments made on the most striking or representative findings. Finally, the implications of the recent advances in the understanding of molecular genetic mechanisms of body weight regulation on prevention and therapeutic intervention of obesity will be discussed.     

The radiation bystander effect and its potential implications for human health

A long-held dogma in radiation biology has been that the biological effects of exposure to ionizing radiation occur as a result of damage in directly irradiated cells and that no effect would occur in neighboring unirradiated cells. This paradigm has been frequently challenged by reports of radiation effects in unirradiated or 'bystander' cells receiving signals from directly irradiated cells, an issue that may have substantial impact on radiation risk assessment and development of radiation-based therapies. Radiation-induced bystander effects have been shown in single-cell systems in vitro for an array of cancer relevant endpoints, and may trigger damage in more complex 3-D tissue systems. They may be mediated by soluble factors released by irradiated cells into the extracellular environment and/or by the passage of mediator molecules through gap-junction intercellular communication. To date, evidence that radiation-associated bystander or abscopal responses are effectual in vivo has been limited, but new data suggest that they may significantly affect tumor development in susceptible mouse models. Further understanding of how the signal/s is transmitted to unirradiated cells and tissues and how it provokes long-range and significant responses is crucial. By summarizing the existing evidence of radiation induced bystander-like effects in various systems with emphasis on in vivo findings, we will discuss the potential mechanisms involved in these observations and how effects in bystander cells contribute to uncertainties in assessing cancer risks associated with radiation exposure.     

Changing air mass frequencies in Canada: potential links and implications for human health

Many individual variables have been studied to understand climate change, yet an overall weather situation involves the consideration of many meteorological variables simultaneously at various times diurnally, seasonally, and yearly. The current study identifies a full weather situation as an air mass type using synoptic scale classification, in 30 population centres throughout Canada. Investigative analysis of long-term air mass frequency trends was completed, drawing comparisons between seasons and climate zones. We find that the changing air mass trends are highly dependent on the season and climate zone being studied, with an overall increase of moderate (‘warm’) air masses and decrease of polar (‘cold’) air masses. In the summertime, general increased moisture content is present throughout Canada, consistent with the warming air masses. The moist tropical air mass, containing the most hot and humid air, is found to increase in a statistically significant fashion in the summertime in 46 % of the areas studied, which encompass six of Canada’s ten largest population centres. This emphasises the need for heat adaptation and acclimatisation for a large proportion of the Canadian population. In addition, strong and significant decreases of transition/frontal passage days were found throughout Canada. This result is one of the most remarkable transition frequency results published to date due to its consistency in identifying declining trends, coinciding with research completed in the United States (US). We discuss relative results and implications to similar US air mass trend analyses, and draw upon research studies involving large-scale upper-level air flow and vortex connections to air mass changes, to small-scale meteorological and air pollution interactions. Further research is warranted to better understand such connections, and how these air masses relate to the overall and city-specific health of Canadians.     

Drug-resistant malaria: molecular mechanisms and implications for public health

Resistance to antimalarial drugs has often threatened malaria elimination efforts and historically has led to the short-term resurgence of malaria incidences and deaths. With concentrated malaria eradication efforts currently underway, monitoring drug resistance in clinical settings complemented by in vitro drug susceptibility assays and analysis of resistance markers, becomes critical to the implementation of an effective antimalarial drug policy. Understanding of the factors, which lead to the development and spread of drug resistance, is necessary to design optimal prevention and treatment strategies. This review attempts to summarize the unique factors presented by malarial parasites that lead to the emergence and spread of drug resistance, and gives an overview of known resistance mechanisms to currently used antimalarial drugs.     

Beneficial effects of human viruses

In keeping with the theme of this Yale-China symposium, we discuss some unexpected dividends which have been derived from the basic study of five viruses to which man has been exposed. Inquiring into the behavior of these viruses for their own sake has not only produced an increase in basic understanding of biologic processes, but has provided concepts and techniques which will broaden our knowledge of the etiology, pathogenesis, and treatment of human diseases which are unrelated to viruses.     

Deciphering mechanisms and implications of bacterial translocation in human health and disease

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Trans fatty acids: effects on cardiometabolic health and implications for policy

In both developed and developing countries, trans fatty acids (TFA) are largely consumed from partially hydrogenated vegetable oils. This article focuses on TFA as a modifiable dietary risk factor for cardiovascular disease, reviewing the evidence for lipid and non-lipid effects; the relations of trans fat intake with clinical endpoints; and current policy and legislative issues. In both observational cohort studies and randomized clinical trials, TFA adversely affect lipid profiles (including raising LDL and triglyceride levels, and reducing HDL levels), systemic inflammation, and endothelial function. More limited but growing evidence suggests that TFA also exacerbate visceral adiposity and insulin resistance. These potent effects of TFA on a multitude of cardiovascular risk factors are consistent with the strong associations seen in prospective cohort studies between TFA consumption and risk of myocardial infarction and coronary heart disease (CHD) death. The documented harmful effects of TFA along with the feasibility of substituting partially hydrogenated vegetable oils with healthy alternatives indicate little reason for continued presence of industrially produced TFA in food preparation and manufacturing or in home cooking fats/oils. A comprehensive strategy to eliminate the use of industrial TFA in both developed and developing countries, including education, food labeling, and policy and legislative initiatives, would likely prevent tens of thousands of CHD events worldwide each year.     

The gender differences in health effects of environmental cadmium exposure and potential mechanisms

On a viewpoint of gender differences in Cd body burden and its health effects, we reviewed the population-based research including our own which conducted in Japan, Thailand, Australia, Poland, Belgium and Sweden to assess health effects of human exposure to environmental cadmium and their potential mechanisms. As a result, six risk factors in Cd health effects in women have been identified; (1) more serious type of renal tubular dysfunction, (2) difference in calcium metabolism and its regulatory hormones, (3) kidney sensitivity; difference in P450 phenotype, (4) pregnancy, (5) body iron store status, and (6) genetic factors. Further studies of Cd toxicity targeted to women would now appear necessary.     

An evolutionary perspective on human physical activity: implications for health

At present, human genes and human lives are incongruent, especially in affluent Western nations. When our current genome was originally selected, daily physical exertion was obligatory; our biochemistry and physiology are designed to function optimally in such circumstances. However, today's mechanized, technologically oriented conditions allow and even promote an unprecedentedly sedentary lifestyle. Many important health problems are affected by this imbalance, including atherosclerosis, obesity, age-related fractures and diabetes, among others. Most physicians recognize that regular exercise is a critical component of effective health promotion regimens, but there is substantial disagreement about details, most importantly volume: how much daily caloric expenditure, as physical activity, is desirable. Because epidemiology-based recommendations vary, often confusing and alienating the health-conscious public, an independent estimate, arising from a separate scientific discipline, is desirable, at least for purposes of triangulation. The retrojected level of ancestral physical activity might meet this need. The best available such reconstruction suggests that the World Health Organization's recommendation, a physical activity level of 1.75 ( approximately 2.1 MJ (490 kcal)/d), most closely approximates the Paleolithic standard, that for which our genetic makeup was originally selected.     

Various biological effects of solar radiation on skin and their mechanisms: implications for phototherapy

ABSTRACT

The skin protects our body from various external factors, such as chemical and physical stimuli, microorganisms, and sunlight. Sunlight is a representative environmental factor that considerably influences the physiological activity of our bodies. The molecular mechanisms and detrimental effects of ultraviolet rays (UVR) on skin have been thoroughly investigated. Chronic exposure to UVR generally causes skin damage and eventually induces wrinkle formation and reduced elasticity of the skin. Several studies have shown that infrared rays (IR) also lead to the breakdown of collagen fibers in the skin. However, several reports have demonstrated that the appropriate use of UVR or IR can have beneficial effects on skin-related diseases. Additionally, it has been revealed that visible light of different wavelengths has various biological effects on the skin. Interestingly, several recent studies have reported that photoreceptors are also expressed in the skin, similar to those in the eyes.

Based on these data, I discuss the various physiological effects of sunlight on the skin and provide insights on the use of phototherapy, which uses a specific wavelength of sunlight as a non-invasive method, to improve skin-related disorders.     

生命科学与人类疾病研究的重要模型——果蝇

黑腹果蝇(Drosophilamelanogaster)是生物学研究中最重要的模式生物之一,它在遗传的染色体理论建立中起到非常重要的作用。由于果蝇自身独特的优势,20世纪70年代以来,它又在发育生物学、神经科学、人类疾病研究等领域得到广泛应用,作出许多新的重要贡献。果蝇在神经退行性疾病研究中是非常有用的模型。可以预期,随着研究手段的丰富及科学的发展,果蝇将作为一种理想的模式生物在生物医学中发挥更大的作用。     

Beneficial health effects of lupeol triterpene: a review of preclinical studies

Since ancient times, natural products have been used as remedies to treat human diseases. Lupeol, a phytosterol and triterpene, is widely found in edible fruits, and vegetables. Extensive research over the last three decades has revealed several important pharmacological activities of lupeol. Various in vitro and preclinical animal studies suggest that lupeol has a potential to act as an anti-inflammatory, anti-microbial, anti-protozoal, anti-proliferative, anti-invasive, anti-angiogenic and cholesterol lowering agent. Employing various in vitro and in vivo models, lupeol has also been tested for its therapeutic efficiency against conditions including wound healing, diabetes, cardiovascular disease, kidney disease, and arthritis. Lupeol has been found to be pharmacologically effective in treating various diseases under preclinical settings (in animal models) irrespective of varying routes of administration viz; topical, oral, intra-peritoneal and intravenous. It is noteworthy that lupeol has been reported to selectively target diseased and unhealthy human cells, while sparing normal and healthy cells. Published studies provide evidence that lupeol modulates the expression or activity of several molecules such as cytokines IL-2, IL4, IL5, ILβ, proteases, α-glucosidase, cFLIP, Bcl-2 and NFκB. This minireview discusses in detail the preclinical studies conducted with lupeol and provides an insight into its mechanisms of action.