Ryanodine receptors and their role in genetic diseases (review)

The field of protein structure prediction is evolving rapidly and in the last few years a number of new methods have been developed and evaluated. However, comparative modeling, or modeling by homology, is still the method of choice when the unknown protein shares any significant sequence similarity with a protein of known structure. The accuracy of the method is highly dependent on the degree of similarity between the target protein and that used as a template. Nevertheless, careful consideration of all the steps performed in the modeling procedure allows useful information to be obtained also from a model based on very low sequence identity.     

The role of vitamins in the pathogenesis and treatment of hyperhomocyst(e)inaemia

The relation between vitamin nutritional status and circulating plasma homocyst(e)ine concentrations is reviewed. Several studies have shown that plasma concentrations of folate, vitamin B12 and pyridoxal 5'-phosphate are inversely associated with plasma total homocyst(e)ine concentrations. Of the three vitamins mentioned above, folate is the most powerful homocyst(e)ine lowering agent and a daily supplement of 0.65 mg/day is sufficient to normalize moderate hyperhomocyst(e)inaemia in most individuals with normal renal function. In patients with severe renal failure, high doses of folate are required to treat hyperhomocyst(e)inaemia. Folic acid is ineffective in reducing plasma total homocyst(e)ine concentrations in patients with a vitamin B12 deficiency. Vitamin B6 supplementation has no effect on fasting plasma total homocyst(e)ine concentrations, but attenuates the post-methionine load plasma homocyst(e)ine peak. At least one report has shown that some individuals appear to be unable to maintain plasma total homocyst(e)ine concentrations in the normal reference range by a dietary intake of folic acid only. Long-term vitamin supplementation may be indicated in these individuals. However, the clinical benefit of vitamin supplementation has not yet been demonstrated and controlled trials are urgently required.     

The role of melatonin in the human fetus (review)

Melatonin, an indole amine, primarily derived from the pineal gland is secreted during the hours of darkness. Melatonin acts as a hormonal transduction of photoperiod influencing the timing of seasonal and daily (circadian) physiological rhythms. Maternal melatonin crosses the placenta and enters the fetal circulation providing photoperiodic information to the fetus influencing the subsequent circadian and seasonal rhythms of the offspring. The function of melatonin in humans is more obscure. However, melatonin has attained prominence as a treatment for disturbed circadian rhythms and sleep patterns which occur as a result of transmeridian travel, shift work or blindness. The biological clock, the hypothalamic suprachiasmatic nuclei (SCN), possesses melatonin receptors, in both the adult and fetal human. This concurs with the reported influence of melatonin on human circadian rhythmicity and indicates that this influence may begin in utero. Melatonin receptors are widespread in the human fetus and occur in both central and peripheral tissue from early in fetal development. Thus, the influence of melatonin on the developing human fetus may not be limited to entraining circadian rhythmicity. Considering the transplacental availability of melatonin to the fetus the ingestion of melatonin by pregnant women may be inadvisable.     

Antioxidant minerals and vitamins. Role in cancer prevention

Cancer is a disease of the genome and free-radicals can damage genomic DNA, hence the interest in the potential protective antioxidant effect of vitamin and minerals. Indeed, the findings of most retrospective studies suggest that diets rich in fruits and vegetables have a protective effect against cancer. Prospective randomized trials have however given controversial results. Beta-carotene, the precursor of vitamin A has been shown to induce regression of precancerous lesions and 13-cis retinoic acid has a preventive effect on the development of a second cancer in patients with epidermoid cancer of the buccal cavity, the pharynx or the larynx although no effect has been observed on the primary cancer. Current research also suggests vitamin C has a potential anticancer effect, particularly for cancer of the stomach, the rectum and the cervix. For vitamin E, epidemiological data give less conclusive results. Several prospective studies suggest the absence of any correlation between vitamin E intake and general risk of cancer. A Chinese trial has shown a decreased incidence of oesophageal and gastric carcinoma while a Finnish trial revealed increased incidence of cancer among smokers treated by beta-carotene and vitamin E. Selenium and zinc intake, based on geographical correlations, has also been suggested to affect cancer incidence, but the results of prospective studies are conflicting. For example in 10 such trials analyzing blood selenium levels and risk of cancer, 4 have demonstrated a significant correlation. Further research is needed but is hindered by the absence of an adequate animal model and the difficulty in conducting large clinical trials. Nevertheless, positive data collected to date must be validated to determine the real effect of dietary preventive measures in the fight against cancer.     

Multiple pregnancy and microelements: zinc (preliminary report)

Incidence, causes and results of permanent ICA clipping during arterial cerebral aneurysm surgery were analyzed in randomized group of 470 patients. Permanent ICA clipping was performed in 6 cases (1.3% of all surgeries). The causes of permanent ICA clipping were ICA wall rupture in 4 (0.9%) cases, bleeding from aneurysms of the ophthalmic segment of the internal carotid artery (ICA) in 2 (0.4%). Atherosclerotic changes of ICA were found and verified by biopsy in all cases of ICA rupture. Two variants of rupture were identified. ICA aneurysm avulsion from the artery in the area of aneurysmal neck with vascular wall defect development in 2 (0.6%) cases; in the second variant, ICA rupture was caused by frontal lobe traction. In the study group aneurysms of ophthalmic segment of ICA were found in 19 cases: intraoperative bleeding rate was 31% (6 cases). ICA was clipped in 33% of all cases of intraoperative bleeding. Among 6 patients with permanent ICA clipping, 5 died. Deaths were caused by cerebral infarction in 4 cases and acute blood loss in 1 case.     

Biologic variation in electrolytes and essential microelements in the blood of neonates and their mothers

Serum concentration and biological variability (CVB%) of total calcium (Ca) magnesium (Mg), iron (Fe), zinc (Zn) and copper (Cu) were determined in 22 sera of maternal and umbilical cord blood in normal pregnancies. The concentrations of Ca (2.48 +/- 0.13 vs 2.27 +/- 0.13 mmol/l), Mg (0.84 +/- 0.06 vs 0.80 +/- 0.07 mmol/l), Fe (24.1 +/- 6.62 vs 10.7 +/- 4.94 mumol/l) and Zn (14.1 +/- 1.78 vs 9.1 +/- 2.21 mumol/l) in the cord sera were significantly higher than in maternal sera (p < 0.01), whereas maternal copper concentrations (36.6 +/- 4.82 vs 9.2 +/- 2.21 mumol/l), were significantly higher than in cord sera (p < 0.01). Biological variability of Ca (5.37 vs 4.84%), Mg (8.39 vs 6.69%), Fe (46.1 vs 27.3%) and Zn (24.1 vs 12.3%) values was higher in the maternal sera than the respective values in the cord sera, while the biological variability of copper in the cord sera was significantly higher than the respective value in the maternal sera (26.7 vs 12.8%). These results are in agreement with those previously reported and suggest that fetal homeostasis of Ca, Mg, Fe and Zn is at least partly independent of maternal factors.     

Microcracks associated with inclusions in as-cast iron and their role during fracture

The formation of voids and microcracks in and around FeO and SiO₂ inclusions during the solidification of pure iron has been investigated and their role during fracture studied. The sizes of these inclusions were varied by an order of magnitude by control of the solidification rate. Voids and microcracks were associated with large (~4 μ) as well as with fine (~0.1 μ) FeO inclusions but not with SiO₂ inclusions. The formation of voids is explained on the basis of solidification shrinkage and the freezing characteristics of FeO. The occurrences of microcracks in the inclusions is explained on the basis of stresses developed due to differential thermal contraction of inclusions and the surrounding matrix during cooling. The effect of these microcracks on the fracture behavior of inclusion-bearing iron is briefly described.     

The SUVIMAX (France) study: the role of antioxidants in the prevention of cancer and cardiovascular disorders

Endospores of Clostridium spp. capable of producing gas in a lactate-containing medium were enumerated from 14 pasteurized milk samples from Wisconsin cheese plants. Concentrations of endospores of lactate-fermenting, gas-producing Clostridium spp. were between 5.0 x 10(-2) and 1.7 x 10(0) MPN ml(-1). Concentrations of presumptive C. tyrobutyricum endospores (defined by subterminal endospore position and lactate dehydrogenase activity) were lower, not exceeding 2.0 x 10(-2) MPN ml(-1). Based on subterminal endospore position, lactate dehydrogenase activity, and a carbohydrate fermentation profile identical to C. tyrobutyricum strain ATCC 25755, five isolates (Ct) were initially characterized as C. tyrobutyricum, a known cause of late-blowing in high-pH cheeses. Twenty-eight other isolates (Cx) produced gas from lactate, but differed from ATCC 25755 in either endospore position, lactate dehydrogenase activity or carbohydrate fermentation profile. When inoculated at high concentrations in Gouda cheese, strain ATCC 25755, two Ct isolates and 18 Cx isolates tested produced gas during ripening. Among the five Ct isolates obtained and two reference strains confirmed as C. tyrobutyricum, there were four qualitatively different volatile organic acid byproduct profiles. Each of the two confirmed C. tyrobutyricum reference strains and five Ct isolates had distinct quantitative cell membrane fatty acid (CMFA) profiles. The Cx isolates represented 14 different volatile organic acid byproduct profiles and each isolate had a unique CMFA profile. Pulsed field gel electrophoresis (PFGE) of DNA from the two confirmed reference C. tyrobutyricum strains, four Ct and three Cx isolates, showed a low degree of relatedness. The results of this study suggest that a heterogeneous group of lactate-fermenting, gas-producing Clostridium spp. may be found in milk. Gas chromatographic analysis of volatile organic acid byproducts or CMFA, and PFGE of DNA are highly discriminating methods for differentiating Clostridium spp. that may cause late blowing in high-pH cheeses.     

Tumor suppressor genes and their role in abnormal production of leukocytes (leukemogenesis)

The retinoblastoma susceptibility gene (RB) and p53 gene are now known to be the prototypes for a class of tumor suppressor genes. Both genes act as a regulator of cell cycle transition at G1/S in many types of cell lineages. Underphosphorylated form of RB protein (Rd) acts as a growth suppressor by blocking exit from G1 through a specific binding to E2F or promoter region of certain growth-associated genes. Phosphorylation of Rb can be viewed as inactivating Rb and allowing cell cycle progression to occur. Differentiation of hematopoietic cell is accompanied with the loss of ability to phosphorylate Rb, indicating that Rb plays an important role in hematopoietic cell growth and differentiation. Abnormalities of RB gene may, therefore, predispose to the development of hematologic malignancies. DNA rearrangement was reported to be present in 1.5-12.1% of cases with primary leukemias, and the absence of RB protein was also observed in 6.3-23.2%. The abnormalities of p53 gene were also frequently observed in hematologic malignancies. DNA rearrangement of p53 was observed in 20-30% of the cases with blastic crisis of CML. Point mutation at the "hot spot" was reported in many types of leukemias, especially in cell lines established from these cases.     

Parent-Adolescent Relationship program (PARD): Relationship enhancement therapy with adolescents and their families (fathers and sons).

Parent–Adolescent Relationship Development (PARD), a relationship enhancement therapy program, was created as a way to improve the relationship between fathers and sons. Fathers and their adolescent sons are brought together in small groups to learn communication and relationship skills. This 10-session program helps fathers and sons remain engaged, improve acknowledgment of their positive feelings toward each other, and feel better about themselves. An excerpt from a PARD group with fathers and sons is presented to exemplify the process and value of this method. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

碳纤维负载零价铁的制备及其去除水溶液中的六价铬

以碳纤维作为载体,采用电沉积法制备碳纤维负载零价铁(PCF^-ZVI),利用扫描电镜、能谱仪及X射线衍射仪对其进行了表征,并考察了其对水溶液中Cr(VI)的去除效果.实验结果表明:碳纤维负载零价铁对水溶液中的Cr(VI)具有很好的去除效果.当铁碳质量比为2∶1,投加量(以Fe⁰计)为2 g·L^-1,Cr(VI)初始质量浓度为20 mg·L^-1,pH值为5,反应时间40min后,Cr(VI)的去除率可达99.96%,碳纤维上负载的零价铁对Cr(VI)的还原过程为准一级动力学,并且还原速率与反应温度的关系符合Arrhenius定律,反应活化能为20.683 k J·mol^-1.     

Comparison of the metabolism of 2 injectable iron preparations (sorbitol iron and polymaltose iron) with the metabolism of transferrin and hemoglobin iron

Iron distribution in the different organs and chemical compartments of the rat has been studied after intravenous injection of 59Fe-sorbitol (Jectofer-Astra) and 59Fe-polymaltose (Fer Hausmann Lucien) and compared with the metabolism of 59Fe bound to transferrin and to hemoglobin. Both parenteral iron preparations are utilized more slowly than Iron-transferrin. The speed of red cell incorporation of 59Fe from sorbitol is similar to the hemoglobin iron utilization (half incorporation in red cells: 4 to 5 days). Iron polymaltose is much more slowly utilized (half incorporation in the red cells: 13 to 15 days). One third of the 59Fe from sorbitol is eliminated in urine, the remaining iron being taken up to 60% by the liver and to 30% by the bone marrow. It is very quickly catabolized, since as early as the first hour after injection most of the 59Fe is bound to polymaltose till the 14th day. Between the third and fourth week 25% of the 59Fe from polymaltose is found in hemosiderin. These metabolic differences are also found in man: 59Fe from iron sorbitol is found in urine after injection, is mobilized by desferrioxamine after six days, and eliminated through dialysis membranes. On the other hand the 59Fe from polymaltose is slowly but completely utilized and not mobilized by desferrioxamine in the first week after injection. The data give the indications for use and the pharmacokinetics of two forms of parenteral iron and oral preparations in the treatment of iron deficiency.     

Influence of lead on metabolism of vitamins B group in alimentary iron deficient rats

Gamma delta T-Cells represent a minor subpopulation of T-lymphocytes in man and their role in normal and diseased human skin is unknown. This article is a comprehensive review of T-lymphocytes bearing the gamma delta T-cell receptor in normal and pathological human skin. Firstly, we have documented the occurrence of gamma delta T-cells in normal skin and in a range of reactive and malignant skin conditions. We have then discussed the experimental findings regarding the repertoire used by gamma delta T-cells in normal human skin and in cutaneous disorders with an increased percentage of gamma delta T-cells.