Effect of phytate on element bioavailability in the second generation of rats

In this paper the relation between long term consumption of a high dose of sodium phytate and the mineral status of the organism is evaluated in rats. For this purpose, element concentrations (Ca, Mg, Fe, Zn, Mn) were determined in liver, heart, testicle, bone and urine of a second generation of Wistar rats, treated with a phytate free diet (AIN-76A) and with the same diet plus 1% phytate as sodium salt. The most significant differences were observed between bone zinc contents of male and female rats. The zinc content of rats fed a 1% phytate as sodium salt diet resulted clearly lower than that found in no-phytate treated rats. Hence, it is concluded that when up to 1% of phytate as sodium salt is consumed together with an equilibrated purified diet (free of phytate), no decrease in mineral bioavailability is observed in second generation rats, except for an indication of lower zinc availability by lower zinc concentrations in some organs, mainly bone. However, using this purified diet, the zinc concentration in bone resulted around 10 times higher than found in rats fed with a common non purified rat chow.     

Human models of aromatase deficiency

Estrogens exert a wide range of biological effects in both sexes also on non-reproductive systems and organs. Human congenital estrogen deficiency, due to an inactivating mutation of the aromatase gene, leads to the lack of the estrogen synthesis, with gonadotropins and circulating testosterone ranging from normal to elevated. The aromatese-deficient females show hyperandrogenism and virilization at birth with ambiguous genitalia. During childhood there are a dysfunction in the LHRH-LH/FSH axis and a progressive delay in bone age. At puberty they show primary amenorrhea, no breast development, worsening of the virilization and the absence of growth spurt. The clinical phenotype in the male affected subjects comprises tall stature, persistent linear growth and delayed bone age, osteopenia/osteoporosis, eunuchoid body proportion, different degrees of glucose-insulin and of fertility impairment. These phenotypes suggest the physiological role of estrogens on the skeleton, on pituitary function, on the reproductive system, on glucose metabolism, being the precise mechanism on each of these functions not yet known in detail. The estradiol replacement treatment leads to a complete epiphyseal closure and to the skeletal maturation. Moreover, the increasing knowledge on the role of estrogen in several metabolic pathways could be important for a better management of several metabolic diseases.     

Effects of corticosterone deficiency and its replacement on Leydig cell steroidogenesis

Clinical and experimental studies have shown the adverse effects of glucocorticoid deficiency/metyrapone treatment on testicular Leydig cell testosterone production. However, molecular mechanisms that underlie the effects of glucocorticoid deficiency on Leydig cell steroidogenesis are not yet determined. Therefore, the present study was designed to assess the mechanism of this phenomenon. Following metyrapone-induced corticosterone deficiency, serum testosterone, and Leydig cell 14C-glucose oxidation were decreased. StAR mRNA and protein levels were significantly increased in Leydig cells of corticosterone-deficient animals. mRNA levels and the specific activities of P(450)scc and 17beta-HSD were decreased by corticosterone deficiency, whereas the activity and mRNA of 3beta-HSD were increased. Simultaneous administration of corticosterone prevented its deficiency-induced changes in Leydig cells. Our results show that metyrapone-induced corticosterone deficiency impairs Leydig cell testosterone production by decreasing the activities of steroidogenic enzymes and their mRNA expression and glucose oxidation.     

Effect of dietary selenium deficiency on the in vitro fertilizing ability of mice spermatozoa

Selenium is an essential micronutrient for mammals, being integral part of antioxidant system. The aim of the study was to evaluate the effect of selenium deficiency on in vitro fertilization (IVF) capacity of spermatozoa and on oxidative stress in these cells. Male C57BL/6N mice were maintained on selenium-deficient or selenium-sufficient diets (0.02 or 0.2 ppm of selenium as selenomethionine, respectively) for 4 months. Liver glutathione peroxidase activity measurements were used to confirm selenium deficiency. Sperm quality and IVF capability among both groups were evaluated. To assess oxidative damage, lipid peroxidation as malondialdehyde production was determined in spermatozoa as well as the testes. Ultrastructural analyses of spermatozoa nuclei using transmission electron microscopy were also performed. The percentage of eggs fertilized with sperm from selenium-deficient mice was significantly decreased by approximately 67%. This reduced fertilization capacity was accompanied by increased levels of lipid peroxidation in both the testes and sperm, indicating that selenium deficiency induced oxidative stress. Consistent with this finding, spermatozoa from selenium-deficient animals exhibited altered chromatin condensation. Deficiency in dietary selenium decreases the reproductive potential of male mice and is associated with oxidative damage in spermatozoa.     

An environmental approach to correcting iodine deficiency: Supplementing iodine in soil by iodination of irrigation water in remote areas

OBJECTIVE: Iodine deficiency disorders continue to be a severe problem in many parts of Central Asia, causing delayed mental development and cretinism in indigenous populations. In some areas, iodized salt has not succeeded in controlling this problem. In southern Xinjiang Province of China, we tried a new method of supplying iodine to rural populations by dripping potassium iodate into irrigation water canals. By this means iodine was distributed into soil, crops, animals and people. This proved feasible and cost effective; it reached all the people, required no medical expertise, required no continuing effort after the initial dripping, and had the important added benefit of improving livestock production. METHODS: We serially monitored iodine concentrations in soil, crops, animal products and human urine for several years after the last dripping. In a similar project in Inner Mongolia, total soil iodine was determined in addition. Here, iodine concentrations in soil, crops, animals and people have been monitored for 4 years after supplementation. RESULTS: After dripping, total iodine increased two-fold, while soluble iodine increased 4-5-fold. Iodine added to soil is available for more than 4 years after a single application. CONCLUSIONS: Potassium iodate added to soil appears to increase soluble iodine out of proportion to the amount added. This effect and the long persistence of dripped iodate in soil contribute to the efficacy and cost effectiveness of this method of iodine supplementation.     

PCR—DGGE法研究葡萄糖-6-磷酸脱氢酶缺乏症基因突变

目的：应用PCR-DGGE法和DNA测序分析云南籍G6PD缺乏症患者基因突变类型和特点、方法应用硝基四氮唑蓝（NBT）纸片法进行G6PD缺乏症定性筛查,G6PD／6PGD比值法验证,应用PCR—DGGE法和DNA测序分析46例云南籍G6PD缺乏症患者基因突变类型和特点。结果：46例云南籍G6PD缺乏症样本中有30例经PCR—DGGE法分析G6PDexon12发现有异常电泳条带,DNA测序证实26例（56、52％）为nt-1388G→A,4例（8.7％）nt-1376G→T．而PCR—DGGE法分析G6PDexon2未发现有异常电泳条带的样本出现。结论：（1）nt-1388G→A（56．52％）、nt-1376G→T（8．7％）是云南省主要的基因突变型也是中国人中最常见的两种突变型,揭示中华民族有着共同的起源;（2）所检样本中未发现nt95A→G。（3）应用PCR—DGGE法结合DNA测序检测G6PD缺乏症患者的基因型,阳性检出率高,方法简便、快捷、灵敏、结果准确可靠。     

肾阴虚证的现代研究进展

肾阴虚证是中医学的基本证型之一。对中医证的研究,基本方法是运用现代科技手段,通过动物实验与临床研究,探讨疾病发生后“证”与人体生理变化、病理、生化等客观指标的关系,尝试揭示证的实质。几十年来,不少学者从细胞、分子等水平上对肾阴虚证本质做了深入地研究,并已取得了一定的成果,某些方面已形成了共识。这不仅丰富和发展了传统的中医’肾阴虚理论,而且为肾阴虚证的临床诊断、治疗、预后判断提供了更客观的、更全面的指导作用．．本文从神经内分泌、免疫、微量元素、脂代谢、自由基、细胞因子与介质、基因等方面对肾阴虚证病理生理的客观化研究进展进行了详细地阐述．     

Iron Deficiency-induced Increase of Root Branching Contributes to the Enhanced Root Ferric Chelate Reductase Activity

In various plant species, Fe deficiency increases lateral root branching. However, whether this morphological alteration contributes to the Fe deficiency-induced physiological responses still remains to be demonstrated. In the present research, we demonstrated that the lateral root development of red clover (Trifolium pretense L.) was significantly enhanced by Fe deficient treatment, and the total lateral root number correlated well with the Fe deficiency-induced ferric chelate reductase (FCR) activity. By analyzing the results from Dasgan et al. (2002), we also found that although the two tomato genotypes line227/1 (P1) and Roza (P2) and their reciprocal F1 hybrid lines ("P1 × P2" and "P2 × P1 ") were cultured under two different lower Fe conditions (10-6 and 10-7 M FeEDDHA), their FCR activities are significantly correlated with the lateral root number. More interestingly, the -Fe chlorosis tolerant ability of these four tomato lines displays similar trends with the lateral root density. Taking these results together, it was proposed that the Fe deficiency-induced increases of the lateral root should play an important role in resistance to Fe deficiency, which may act as harnesses of a useful trait for the selection and breeding of more Fe-efficiant crops among the genotypes that have evolved a Fe deficiency-induced Fe uptake system.     

Potassium deficiency results in accumulation of ultra-high molecular weight poly-beta-hydroxybutyrate in a methane-utilizing mixed culture

Aims: To investigate the effect of various single nutrient deficiencies on poly-β-hydroxybutyrate (PHB) biosynthesis in a methane-utilizing mixed culture (dominant species Methylocystis sp. GB 25 DSM 7674). Methods and Results: Poly-β-hydroxybutyrate accumulation experiments were performed in 7 and 70 l bioreactors and initiated by potassium, sulfur or iron deficiency. After 24 h the PHB content reached levels of 33·6%, 32·6% and 10·4% respectively. Interestingly a polymer with an ultra-high average-weight molecular weight (M_w) of 3·1 MDa was accumulated under potassium-limited conditions. When sulfur and iron were lacking M_w were lower by 20·6 and 41·6%. Potassium-deficiency experiments were furthermore characterized by a maximum specific PHB formation rate 0·08 g g⁻¹residual biomass (R) h⁻¹ and a yield coefficient of 0·45 g PHB g⁻¹ CH₄. Conclusions: Biosynthesis of an ultra-high M_w PHB in a methane-utilizing mixed culture can be induced by potassium deficiency. Significance and Impact of the Study: This study greatly extends the knowledge in the field of bacterial biopolymer formation with gaseous substrates. The special system used here combines the use of methane a low-cost substrate available from natural and renewable sources with the possibility of employing a mixed-culture in an open system for the synthesis of a high-value product.