Changes with malnutrition in the concentration of plasma vitamin D binding protein in growing rats

Skeletal Muscle and the Maintenance of Vitamin D Status

Vitamin D, unlike the micronutrients, vitamins A, E, and K, is largely obtained not from food, but by the action of solar ultraviolet (UV) light on its precursor, 7-dehydrocholesterol, in skin. With the decline in UV light intensity in winter, most skin production of vitamin D occurs in summer. Since no defined storage organ or tissue has been found for vitamin D, it has been assumed that an adequate vitamin D status in winter can only be maintained by oral supplementation. Skeletal muscle cells have now been shown to incorporate the vitamin D-binding protein (DBP) from blood into the cell cytoplasm where it binds to cytoplasmic actin. This intracellular DBP provides an array of specific binding sites for 25-hydroxyvitamin D (25(OH)D), which diffuses into the cell from the extracellular fluid. When intracellular DBP undergoes proteolytic breakdown, the bound 25(OH)D is then released and diffuses back into the blood. This uptake and release of 25(OH)D by muscle accounts for the very long half-life of this metabolite in the circulation. Since 25(OH)D concentration in the blood declines in winter, its cycling in and out of muscle cells appears to be upregulated. Parathyroid hormone is the most likely factor enhancing the repeated cycling of 25(OH)D between skeletal muscle and blood. This mechanism appears to have evolved to maintain an adequate vitamin D status in winter.

A reduced protein diet modulates enzymes of vitamin D and cholesterol metabolism in young ruminants

Besides other adverse effects, a low protein diet has been shown to modulate cholesterol and vitamin D metabolism in monogastric species like rats and humans. As ruminants can increase the efficiency of the rumino-hepatic circulation of urea, it is assumed that goats should be able to compensate for a low dietary protein intake better. After a dietary protein restriction (9% vs. 20%) for six weeks, plasma concentrations of urea, albumin, 1,25-dihydroxyvitamin D₃ and calcium were decreased, while plasma 25-hydroxyvitamin D₃ (25-OHD₃), and total cholesterol were significantly increased in young goats. Because this was not accompanied by any decrease in expression of CYP24A1 mRNA, we investigated mRNA expression of additional enzymes with known 24- and/or 25-hydroxylase activities (CYP2R1, CYP2J2, CYP3 A24, CYP27A1), receptors involved in their regulation (VDR, PXR, RXRα) and vitamin D binding protein (VDBP). CYP2R1expression was stimulated with the low dietary protein intake, negatively correlated with plasma urea and positively associated with serum 25-OHD₃. The greater plasma concentrations of total cholesterol could be explained with the reduction of CYP2J2 and CYP27A1 expression. None of the receptors investigated were affected by the dietary protein restriction but mRNA expression of VDBP was slightly reduced. Taken together our results show that dietary protein restriction has an impact on vitamin D and cholesterol metabolism in ruminants, too. Therefore, further investigations are needed before dietary interventions aiming at diminishing nitrogen excretion can be implemented.

Plasma proteomic analysis of active and torpid greater mouse-eared bats (Myotis myotis)

Hibernation is a physiological adaptation to overcome extreme environmental conditions. It is characterized by prolonged periods of torpor interrupted by temporary arousals during winter. During torpor, body functions are suppressed and restored rapidly to almost pre-hibernation levels during arousal. Although molecular studies have been performed on hibernating rodents and bears, it is unclear how generalizable the results are among hibernating species with different physiology such as bats. As targeted blood proteomic analysis are lacking in small hibernators, we investigated the general plasma proteomic profile of European Myotis myotis and hibernation associated changes between torpid and active individuals by two-dimensional gel electrophoresis. Results revealed an alternation of proteins involved in transport, fuel switching, innate immunity and blood coagulation between the two physiological states. The results suggest that metabolic changes during hibernation are associated with plasma proteomic changes. Further characterization of the proteomic plasma profile identified transport proteins, coagulation proteins and complement factors and detected a high abundance of alpha-fetoprotein. We were able to establish for the first time a basic myotid bat plasma proteomic profile and further demonstrated a modulated protein expression during torpor in Myotis myotis, indicating both novel physiological pathways in bats in general, and during hibernation in particular.

Low serum 25-hydroxyvitamin D level: an independent risk factor for tuberculosis?

BACKGROUND & AIMS

Vitamin D deficiency has been associated with an increased risk of tuberculosis (TB). Low serum vitamin D levels may also be associated with poor nutritional status in TB patients. Therefore, this study aimed at evaluating the association between low serum vitamin D level and TB, regardless of other nutritional factors.

METHODS

Baseline serum 25-hydroxyvitamin D (25(OH)D3) levels in TB patients were measured before treatment and 1 year after treatment onset using liquid chromatography-tandem mass spectrometry, and were compared with 25(OH)D3 levels in controls. Nutritional parameters were also measured in all subjects.

RESULTS

In total, 165 active pulmonary TB patients and 197 controls were included in the study. Significantly higher prevalence of 25(OH)D3 insufficiency (<20 ng/mL) and deficiency (<10 ng/mL) in TB patients was showed compared to controls. Serum 25(OH)D3 levels and nutritional parameters were significantly lower in untreated TB patients than in controls. One year after TB treatment onset, nutritional parameters significantly increased; however, serum 25(OH)D3 levels in TB patients showed no significant improvement compared to baseline.

CONCLUSIONS

These results suggest that a low serum 25(OH)D3 level might be a risk factor for TB, independent of nutritional status.

Hypovitaminosis D in developing countries-prevalence, risk factors and outcomes

Hypovitaminosis D is a prevalent disorder in developing countries. Clinical manifestations of hypovitaminosis D include musculoskeletal disorders, such as nonspecific muscle pain, poor muscle strength and low BMD, as well as nonmusculoskeletal disorders, such as an increased risk of respiratory infections, diabetes mellitus and possibly cardiovascular diseases. In developing countries, the prevalence of hypovitaminosis D varies widely by and within regions; prevalence ranges between 30-90%, according to the cut-off value used within specific regions, and is independent of latitude. A high prevalence of the disorder exists in China and Mongolia, especially in children, of whom up to 50% are reported to have serum 25-hydroxyvitamin D levels <12.5 nmol/l. Despite ample sunshine throughout the year, one-third to one-half of individuals living in Sub-Saharan Africa and the Middle East have serum 25-hydroxyvitamin D levels <25 nmol/l, according to studies published in the past decade. Hypovitaminosis D is also prevalent in children and the elderly living in Latin America. Risk factors for hypovitaminosis D in developing countries are similar to those reported in Western countries and include extremes of age, female sex, winter season, dark skin pigmentation, malnutrition, lack of sun exposure, a covered clothing style and obesity. Clinical trials to assess the effect of vitamin D supplementation on classical and nonclassical clinical outcomes in developing countries are needed.

[Carbohydrate study for 40 years]

This review describes the carbohydrate study and the natural product related to the glycoside chemistry. What shall the people in the field of pharmacognosy and natural products chemistry search in scene in future? Forty years before while isolating dimeric compound having naphthoquinonepyrone skeleton from the coloring material produced by the pathogen that hosted in wheat and caused rotten root disease, silica gel has to be treated with oxalic acid to reduce the absorbency before separation. However now a days, availability of reversed phase adsorbents for liquid chromatography has made the separation and isolation of complex compounds possible, easy and rapid. With the advancement of mechanical/physicochemical analytic methods, it has even been possible to isolate traces of compounds present in complex. This advancement has made it possible to determine structure of saponins and complex polysaccharides without decomposition and carry out in vitro bioassay at the same time using various cells on-line. Further, this review describes the oligosaccharide syntheses and biological activities of glycosphingolipids, focusing especially on those found in invertebrates.

Vitamin D binding protein, a new nutritional marker in cystic fibrosis patients

BACKGROUND

Vitamin D binding protein (DBP) is a multifunctional transport protein with a decreased serum concentration in cystic fibrosis (CF). The present study investigates the importance of DBP and its role as an alternative nutritional marker in CF.

METHODS

DBP phenotypes of 116 CF patients were determined electrophoretically. Serum DBP was measured by immunonephelometry. Parathormone was assessed by an immunoradiometric assay. Serum 25OH vitamin D(3), 1,25(OH)(2) vitamin D(3) and leptin concentrations were determined by a radioimmunoassay. Serum alpha-tocopherol was measured by HPLC. Routine chemistry parameters were assessed using commercial methods. The Prognostic Inflammatory and Nutritional Index was calculated.

RESULTS

Decreased serum DBP concentrations were observed in the CF group. Total cholesterol, low-density lipoprotein (LDL)-cholesterol, triglyceride concentration, alpha-tocopherol and a low nutritional status correlated positively with DBP. Lipoprotein precipitation demonstrated a partial presence of DBP in very-low-density lipoprotein and LDL. Furthermore, DBP was positively correlated with serum leptin concentration.

CONCLUSIONS

The present study demonstrates a positive correlation between DBP and serum lipids. Serum DBP concentration can be considered as a nutritional marker (especially for lipids).

Beneficial effects of green tea--a review

Tea is the most consumed drink in the world after water. Green tea is a 'non-fermented' tea, and contains more catechins, than black tea or oolong tea. Catechins are in vitro and in vivo strong antioxidants. In addition, its content of certain minerals and vitamins increases the antioxidant potential of this type of tea. Since ancient times, green tea has been considered by the traditional Chinese medicine as a healthful beverage. Recent human studies suggest that green tea may contribute to a reduction in the risk of cardiovascular disease and some forms of cancer, as well as to the promotion of oral health and other physiological functions such as anti-hypertensive effect, body weight control, antibacterial and antivirasic activity, solar ultraviolet protection, bone mineral density increase, anti-fibrotic properties, and neuroprotective power. Increasing interest in its health benefits has led to the inclusion of green tea in the group of beverages with functional properties. However, although all the evidence from research on green tea is very promising, future studies are necessary to fully understand its contributions to human health, and advise its regular consumption in Western diets, in which green tea consumption is nowadays limited and sporadic.

Biological and clinical aspects of the vitamin D binding protein (Gc-globulin) and its polymorphism

The vitamin D binding protein (DBP) is the major plasma carrier protein of vitamin D and its metabolites. Unlike other hydrophobic hormone-binding systems, it circulates in a considerably higher titer compared to its ligands. Apart from its specific sterol binding capacity, DBP exerts several other important biological functions such as actin scavenging, fatty acid transport, macrophage activation and chemotaxis. The DBP-gene is a member of a multigene cluster that includes albumin, alpha-fetoprotein, and alpha-albumin/afamin. All four genes are expressed predominantly in the liver with overlapping developmental profiles. DBP is a highly polymorphic serum protein with three common alleles (Gc1F, Gc1S and Gc2) and more than 120 rare variants. The presence of unique alleles is a useful tool for anthropological studies to discriminate and to reveal ancestral links between populations. Many studies have discussed the link between DBP-phenotypes and susceptibility or resistance to osteoporosis, Graves' disease, Hashimoto's thyroiditis, diabetes, COPD, AIDS, multiple sclerosis, sarcoidosis and rheumatic fever. This article reviews the general characteristics, functions and clinical aspects of DBP.

Therapeutic potential of vitamin D-binding protein

Vitamin D-binding protein (DBP) is a multi-functional plasma protein with many important functions. These include transport of vitamin D metabolites, control of bone development, binding of fatty acids, sequestration of actin and a range of less-defined roles in modulating immune and inflammatory responses. Exploitation of the unique properties of DBP could enable the development of important therapeutic agents for the treatment of a variety of diseases.

Vitamin D-deficiency in Asia

Vitamin D-deficiency rickets is an important disease of childhood in China. It occurs in all regions (20-53 degrees N) but is more prevalent in the north. A survey in Beijing indicated that Vitamin D-deficiency (plasma 25(OH)D concentration <12.5 nmol/l) occurred in more than 40% of adolescent girls in winter. Dietary calcium was often as low as 350 mg per day and a positive correlation was found between this and both bone mineral density (BMD) and Vitamin D status. In a subsequent intervention study with 757 Beijing schoolgirls, a daily supplement of milk, fortified with calcium, was provided on school days for 24 months. From anthropometric and bone density data, it is evident that the increased calcium intake from milk, had significant effects on bone and that deficiencies of both calcium and of Vitamin D had been affecting bone growth and development. In neighboring Mongolia (42 degrees -50 degrees N), rickets is also common, but its prevalence has increased since 1990. A 2-year survey (2000-2002) in Mongolia indicated that, as in China, a low intake of calcium and limited exposure to solar ultraviolet (UV) light in summer were associated with Vitamin D-deficiency. However, over the last decade, malnutrition has become widespread. It now appears that malnutrition impairs the efficiency of the utilization of Vitamin D obtained in summer. Hence, a number of factors need to be addressed to prevent Vitamin D-deficiency during growth.