The roles of trace elements in foetal and neonatal development

Manganese, zinc and copper are essential for normal prenatal and neonatal development. Manganese deficiency causes skeletal abnormalities, congenital ataxia due to abnormal inner ear development, and abnormal brain function. Depression of mucopolysaccharide synthesis and manganese superoxide dismutase activity may be fundamental to ultrastructural and other defects. In copper deficiency, neurological and skeletal abnormalities are due to impairment of phospholipid synthesis and collagen crosslinking, and possibly to low activity of copper metalloenzymes. The fundamental defect leading to the extremely teratogenic effects of zinc deficiency is related to depressed synthesis of DNA. In the neonatal period, poor survival and growth and depressed function of the immune system are salient features. Developmental patterns of trace element concentrations in various tissues suggest that important changes in metabolic regulation of trace elements may occur during the neonatal period. This hypothesis is being investigated by studies of molecular localization of trace elements in certain neonatal tissues, in conjunction with similar observations in milk.     

Trace elements in animals.

Trace element deficiency and toxicity in animals induces a wide variety of clinical effects although few are sufficiently specific to permit diagnosis without supporting investigation of changes in tissue trace element content or of the activity of metabolic processes influenced by trace element supply. Study of such trace element dependent processes has shown that extensive changes often arise before overt signs of disease appear. Some of these subclinical effects have pathological consequences and thus cannot be ignored when seeking correlations between geochemical anomalies and disease incidence. Many past estimates of the quantitative requirements of animals for the essential trace elements are imprecise. Although recent work is providing clearer definition of requirements, many common dietary components have a marked influence upon the efficiency with which such elements can be utilized from the diet. Recent evidence indicates that such antagonists influence both the absorption and the subsequent fate of essential and toxic elements in body tissues and these processes have to be taken into account when investigating the aetiology of disorders believed to be attributable to anomalies in trace element supply. Their existence is not always detectable if attention is confined to the trace element analysis of body tissues or to the nature of clinical lesions. Provided the complexity of soil-plant-animal relations with respect to trace element supply is fully recognized in the interpretation of data, the geochemical approach to the initial recognition of areas associated with a high risk of anomalies in trace element supply to animals and man has considerable potential value. This is already apparent from investigations upon the incidence of trace element problems in animals. As yet, its validity for similar purposes in man is less fully established.     

Apoptosis may underlie the pathology of zinc-deficient skin

The trace element zinc is essential for the survival and function of all cells. Zinc deficiency, whether nutritional or genetic, is fatal if left untreated. The effects of zinc deficiency are particularly obvious in the skin, seen as an erythematous rash, scaly plaques, and ulcers. Electron microscopy reveals degenerative changes within keratinocytes. Despite the well-documented association between zinc deficiency and skin pathology, it is not clear which cellular processes are most sensitive to zinc deficiency and could account for the typical pathological features. We used the cultured HaCaT keratinocyte line to obtain insight into the cellular effects of zinc deficiency, as these cells show many characteristics of normal skin keratinocytes. Zinc deficiency was induced by growing cells in the presence of the zinc chelator, TPEN, or by growth in zinc-deficient medium. Growth of cells in zinc-deficient medium resulted in a 44% reduction of intracellular zinc levels and a 75% reduction in the activity of the zinc-dependent enzyme, 5'-nucleotidase, relative to the control cells. Over a period of 7 days of exposure to zinc-deficient conditions, no changes in cell viability and growth, or in the cytoskeletal and cell adhesion systems, were found in HaCaT cells. At 7 days, however, induction of apoptosis was indicated by the presence of DNA fragmentation and expression of active caspase-3 in cells. These results demonstrate that apoptosis is the earliest detectable cellular change induced by zinc deficiency in HaCaT keratinocytes. Our observations account for many of the features of zinc deficiency, including the presence of degenerate nuclei, chromatin aggregates and abnormal organization of keratin, that may represent the later stages of apoptosis. In summary, a major causal role for apoptosis in the pathology of zinc deficiency in the skin is proposed. This role is consistent with the previously unexplained diverse range of degenerative cellular changes seen at the ultrastructural level in zinc-deficient keratinocytes.     

Characteristic properties of metabolism of the yeast <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis> during the synthesis of α-ketoglutaric acid from ethanol

The study of free amino acid content in Yarrowia lipolytica cells grown on ethanol under thiamine deficiency showed that glutamate, alanine, and γ-aminobutyric acid (γ-ABA) occurred in the highest concentrations among the present 17 free amino acids. The culture liquid contained no amino acids. Analysis of the enzymes of oxidative metabolism in the yeast grown under these conditions showed that the cell-free homogenate contained substantial activity of glutamate decarboxylase, γ-ABA transaminase, and succinyl semialdehyde dehydrogenase. This result indicated the formation of succinate from glutamate in a reaction catalyzed by 4-aminobutyrate aminotransferase (γ-aminobutyrate bypass) under severe thiamine deficiency. These studies lead to the conclusion that cultivation of the yeast Y. lipolytica on ethanol under thiamine deficiency causes adaptive stress-induced metabolic changes. Increase of ammonium nitrogen consumption and excretion of α-ketoglutaric acid are indicative of physiological changes, the functioning of the γ-aminobutyrate bypass and high activity of malate dehydrogenase are manifestations of metabolic changes, and increased activities of the transamination reactions reflect the changes in nitrogen metabolism.     

The immunological homunculus (immunculus) in normal state and pathology

The immunculus is considered as the system (general network) of constitutively expressed natural autoantibodies against different extracellular, membrane, cytoplasmic, and nuclear self-antigens (ubiquitous and organ-specific). It is specially noted that the repertoires of natural autoantibodies are surprisingly constant in healthy persons, independent of gender and age, and characterized by only minimal individual peculiarities (individual immune fingerprints). On the other hand, abnormal metabolic changes which precede the clinical manifestation of different diseases showed easily detected changes, rather quantitative than qualitative, in the systems of natural autoantibodies in patients' sera (immunculus distortions). This phenomena could supposedly be used for "mapping" the state of physiological norm in terms of the millions of natural autoantibody repertoires, and for elaboration of the methods for early (preclinical) detection of potentially pathogenic metabolic changes. Could the individual features of the general network of constitutively expressed natural autoantibodies reflect the functional state of the body and be used for "mapping" of normal and pathological functional state? Could the changes in production of some biologically active natural autoantibodies not only reflect the state of the body, but be used for partial compensation of functional deficiency of certain molecular systems? These and related questions are discussed in this article. The research project "immunculus" is proposed for international cooperative investigations.     

Vitamin requirement study techniques

Vitamin requirement studies have been conducted for 50 years using growth and clinical signs of deficiency for quantitative studies. Histological confirmation of apparent signs confirm and establish subclinical measurements for deficiency. Test diets for these studies with positive experimental control over the test vitamin have been developed using varying degrees of vitamin-free ingredients in the formulations. Haematology values and microanatomical changes reflect failures of a metabolic system and provide convincing data for requirements. Quantitative studies have used specific test diets plus increasing aliquots of the test vitamin, coupled with growth response, tissue storage analysis, and specific enzyme system activity. Results have been reported for levels which support normal growth, clinical enzyme saturation, and maximum liver or other tissue storage levels. Megavitamin intake studies have been correlated with improved resistance to stress and certain fish diseases. Statistical measurement of response to various parameters used become essential for quantitative vitamin requirement determinations. Early studies using vitamin analysis of feedstuffs mixtures coupled with growth response, absence of deficiency signs, and liver or tissue storage have been superseded by diets with more positive control of all nutrients, including the vitamin to be tested. Sparing effects of one vitamin upon another can be demonstrated. Various vitamer forms may have different activity to supply physiological requirements for the vitamin. Most water-soluble vitamins act as co-enzymes in metabolic systems. Some fat-soluble vitamins have molecular functions acting as hormones, free radical traps, intracellular reducing agents, pigments, antioxidants, etc. A guide for vitamin requirements or dietary allowances should be followed when research plans are made to conduct vitamin requirement studies.     

Changes in the expression of receptors of steroid hormones in the development of partial androgen deficiency of aging men (PADAM)

This work is devoted to the vital topic of the influence of partial androgen deficiency of aging men (PADAM) on the development of cells with androgen receptors. The results obtained in this study suggest a conclusion that the production of testosterone by some tumors and tissues of the peritumorous zone, which is accompanied by increased proliferative activity and disturbance of the regulation of the cell cycle, is caused by PADAM. The given changes are directed at compensating for testicular deficiency (in particular at overcoming the androgen-dependent stage of development of androgen-sensitive cells). These changes are a partial manifestation of metabolic syndrome (X-syndrome). The atypical cells, which unavoidably develop during metabolic syndrome, are dealt with by means of the immune system, whose capabilities become less and less adequate in the given circumstances.     

Applicability of the fluorescein diacetate assay for metabolic activity measurement of Microcystis aeruginosa (Chroococcales,Cyanobacteria)

The fluorescein diacetate (FDA) assay has been widely used to measure metabolic activity in phytoplankton. It was found that FDA fluorescence values did not decrease in some stressed cells, demonstrating that the applicability of the method needs to be assessed further in the context of growth‐influencing conditions. In the present study, changes of FDA fluorescence values were studied in bloom‐forming cyanobacterial Microcystis aeruginosa Kütz cells under stress conditions such as nitrogen (N) or phosphorus (P) deficiency, or darkness and low temperature (10°C), respectively. The results demonstrated that esterase activity decreased immediately in dark‐stressed cells, which correlated with the decline of biomass and photosynthetic activity. Under the other three stress conditions, however, especially at low temperature, the cells lost photosynthetic activity but had the highest esterase activity, which was five times higher than the control group. These findings contrast with the assay criteria that the expression of a stain should reflect the change of photosynthetic activity and that stressed cells should have a lower staining intensity than the control cells. According to these results, the esterase activity response was dependent on environmental factors. Furthermore, higher fluorescence intensity did not mean higher metabolic activity, but a discrepant value indicated a severe stress.     

Pathological consequences of copper deficiency and cobalt deficiency

Aspects of the pathology of copper deficiency in several species, and cobalt deficiency in sheep, are summarized. An attempt is made to interpret morphological changes in copper-deficient animals in terms of biochemical defects. The common denominator may be mitochondrial lesions, with a generalized effect on energy-dependent synthetic functions of the cell. In copper deficiency, such defects can be attributed to depletion of copper-dependent enzymes, while deficiency of cobalt in ruminants is, in effect, deficiency of vitamin B12. The pathological consequences of vitamin B12 deficiency form a syndrome, notable features of which are neurological and muscular lesions, in which the metabolic consequences of hepatic damage may play a significant role.     

代谢流量比率分析及其在代谢工程中的应用

细胞内代谢反应流量在系统理解细胞代谢特性和指导代谢工程改造等方面都起着重要的作用。由于代谢流量难以直接测量得到,在很多情况下通过跟踪稳定同位素在代谢网络中的转移并进行相应的模型计算能有效地定量代谢流量。代谢流量比率分析法能够高度体现系统的生物化学真实性、辨别细胞代谢网络的拓扑结构,并且能够相对简单快速地定量反应速率等,因此受到代谢工程研究者越来越多的重视。以下着重介绍并讨论了利用代谢物同位体分布信息分析关键代谢节点合成途径的流量比率、基于流量比率的代谢流量解析、以及应用于代谢工程等的相关原理、实验测量、数据分析、使用条件等,以期充分发挥代谢流量比率分析法的优势,并将其拓展推广至更多细胞体系的代谢特性阐明和代谢工程改造中去。     

A proteomics approach to identify changes in protein profiles in pre-cancerous colon

The development of colon cancer is characterised by alterations in multiple genetic and epigenetic pathways in colon tissue leading ultimately to deregulation of colon epithelial cells. Early detection is an important factor in decreasing colon cancer deaths. Proteomic techniques were used to identify potential early markers in colon tissue exhibiting pre-cancerous activity that may characterise pathological changes in a chemically induced colon cancer rat model. Protein profiles were assessed in soluble and insoluble fractions prepared from distal colon of rats treated with the colonotropic carcinogen, dimethylhydrazine. Alterations in protein profiles were associated with the presence of aberrant crypt foci, hyperplasia and dysplasia, microanatomical changes, and metabolic changes in rat colon. These changes may have a potential role in the identification of pre-pathological features preceding colon tumorigenesis.     

Regionally selective alterations in enzymatic activities and metabolic fluxes during thiamin deficiency

To further elucidate the molecular basis of the selective damage to various brain regions by thiamin deficiency, changes in enzymatic activities were compared to carbohydrate flux through various pathways from vulnerable (mammillary bodies and inferior colliculi) and nonvulnerable (cochlear nuclei) regions after 11 or 14 days of pyrithiamin-induced thiamin deficiency. After 11 days,large decreases (–43 to –59%) in transketolase (TK) occurred in all 3 regions; 2-ketoglutarate dehydrogenase (KGDHC) declined (–45%), but only in mammillary bodies; pyruvate dehydrogenase (PDHC) was unaffected. By day 14, TK remained reduced by 58%–66%; KGDHC was now reduced in all regions (–48 to –55%); PDHC was also reduced (–32%), but only in the mammillary bodies. Thus, the enzyme changes did not parallel the pathological vulnerability of these regions to thiamin deficiency.¹⁴CO₂ production from¹⁴C-glucose labeled in various positions was utilized to assess metabolic flux. After 14 days, CO₂ production in the vulnerable regions declined severely (–46 to 70%) and approximately twice as much as those in the cochlear nucleus. Also by day 14, the ratio of enzymatic activity to metabolic flux increased as much as 56% in the vulnerable regions, but decreased 18 to 30% in the cochlear nuclei. These differences reflect a greater decrease in flux than enzyme activities in the two vulnerable regions. Thus, selective cellular responses to thiamin deficiency can be demonstrated ex vivo, and these changes can be directly related to alterations in metabolic flux. Since they cannot be related to enzymatic alterations in the three regions, factors other than decreases in the activity of these TPP-dependent enzymes must underlie selective vulnerability in this model of thiamin deficiency.Abbreviations KGDHC 2-ketoglutarate dehydrogenase complex EC 1.2.4.2., EC 2.3.1.61, EC 1.6.4.3. - PDHC pyruvate dehydrogenase complex EC 1.2.4.2., EC 2.3.1.12, EC 1.6.4.3 - TK transketolase (EC 2.2.1.1) - TPP thiamin pyrophosphate     

Fully habituated sugarbeet callus: Under permanent stress?

Summary A fully habituated nonorganogenic (HNO) sugarbeet callus line, compared to a normal (hormone dependent) one originated from the same plant exhibits many characteristics of a vitrified tissue and several traits common to animal cancer cells. Four types of biochemical or metabolic characteristics of HNO callus [deficiency of tetrapyrrole-containing compounds; lipid (per)oxidation and malondialdehyde formation; high activity of enzyme protective systems; proline, glutamate, and polyamine accumulation] may be interpreted as responses to stress. The deficiency of tetrapyrrole-containing compounds can be considered an indirect protection against activated forms of oxygen as well as the higher activity of the antioxidant defense mechanisms. This fits with suggestions in the literature that the autonomy associated with plant cancer tissue is explained on the basis of antioxidants as stimulators of cell division and corresponding inhibitors of cell differentiation. Such changes occurring in HNO cells may in turn be responsible for a greater absorption and sensitivity to ammonium ions. An altered nitrogen metabolism leads to proline, glutamate, and polyamine accumulation. Lipid peroxidation and malondialdehyde accumulation rapidly occur in this very sensitive HNO callus in a prolonged culture cycle, which might be related to the appearance of necrosis bands. Thus there are arguments allowing us to consider HNO cells as mutants adapted to some stresses, but resulting changes in their structure might have rendered them still more sensitive to other factors.     

The immune system and the impact of zinc during aging

The trace element zinc is essential for the immune system, and zinc deficiency affects multiple aspects of innate and adaptive immunity. There are remarkable parallels in the immunological changes during aging and zinc deficiency, including a reduction in the activity of the thymus and thymic hormones, a shift of the T helper cell balance toward T helper type 2 cells, decreased response to vaccination, and impaired functions of innate immune cells. Many studies confirm a decline of zinc levels with age. Most of these studies do not classify the majority of elderly as zinc deficient, but even marginal zinc deprivation can affect immune function. Consequently, oral zinc supplementation demonstrates the potential to improve immunity and efficiently downregulates chronic inflammatory responses in the elderly. These data indicate that a wide prevalence of marginal zinc deficiency in elderly people may contribute to immunosenescence.     

Energy and glucose pathways in thiamine deficient primary rat brain microvascular endothelial cells

Thiamine deficiency (TD) results in lactate acidosis, which is associated with neurodegeneration. The aim of this study was to investigate this alteration in primary rat brain endothelia. Spectrophotometric analysis of culture media revealed that only a higher concentration of pyrithiamine, which accelerates the intracellular blocking of thiamine, significantly elevated the lactate level and lactate dehydrogenase activity within 7 days. The medium without pyrithiamine and with a thiamine concentration comparable to pathophysiological plasma levels mildly reduced only the activity of transketolase. This suggests that significant metabolic changes may not occur at the early phase of TD in cerebral capillary cells, while anaerobic glycolysis in capillaries may be mediated during late stage/chronic TD.     

Neurotransmitter function in thiamine-deficiency encephalopathy

The encephalopathy caused by severe thiamine depletion of the mammalian CNS is accompanied by regionally selective changes in neurotransmitter function. Thiamine deficiency induced by administration of the central thiamine antagonist, pyrithiamine, causes more widespread lesions and accompanying changes in neurotransmitter function than does the deficiency state induced by chronic deprivation of the vitamin. There is convincing evidence for a central muscarinic cholinergic lesion in pyrithiamine-treated rats and neuropharmacological studies show that this lesion is partially responsible for the neurological deficit resulting from this treatment. There is also good evidence to suggest that thiamine deprivation selectively affects cerebellar afferent and efferent systems. Included in these are a loss of serotoninergic mossy fibres and of the functional integrity of glutamatergic granule cells. In addition, abnormalities of both nerve terminals and glial cells are found in lateral vestibular nucleus and it has been proposed that a loss of Purkinje cell terminals and concomitant decreases of pontine GABA may reflect these changes. The selective vulnerability of brain structures to thiamine deprivation is reflected in (i) the turnover rate of total thiamine in these areas and (ii) the selective decreases in activity of the thiamine pyrophosphate dependent enzyme pyruvate dehydrogenase.     

Trace Element Profiles in Single Strands of Human Hair Determined by HR-ICP-MS

Trace element analysis of human hair has the potential to reveal retrospective information about an individual's nutritional status and exposure. As trace elements are incorporated into the hair during the growth process, longitudinal segments of the hair may reflect the body burden during the growth period. We have evaluated the potential of human hair to indicate exposure or nutritional status over time by analysing trace element profiles in single strands of human hair. The hair strands from five healthy and occupationally unexposed subjects were cut into 1-cm long segments starting from the scalp. By using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS), we achieved profiles of 12 elements in single strands of human hair, namely, Ag, As, Au, Cd, Cu, Hg, Fe, Pb, Se, Sr, U and Zn. We have shown that trace element analysis along single strands of human hair can yield information about essential and toxic elements, and for some elements, can be correlated with seasonal changes in diet and exposure. The information obtained from the trace element profiles of human hair in this study substantiates the potential of hair as a biomarker.     

Minireview: physiological and pharmacological properties of vanadium

Vanadium is distributed extensively in nature. It is a trace element and is present in almost all living organisms including man. Even though vanadium was originally recognized for its ability to inhibit membrane Na+-K+-ATPase, various laboratory studies now document that this element has the capacity to affect the activity of various intracellular enzyme systems and may modify their physiological functions. Vanadium may be an essential element for normal development and may play an important role in various homeostatic mechanisms, and thus vanadium deficiency may prove to be an important concern. Abnormalities in biological disposition of vanadium may be involved in the pathogenesis of certain neurological disorders or cardiovascular diseases. While the essentiality of this element for living organisms is yet to be established with certainty, vanadium has become an increasingly important element and is used extensively in various heavy industries such as steel, oil, etc.; thus, the incidence of exposure to toxic levels of vanadium to industrial workers has been an increasing concern for toxicologists. To date, little information is available on the physiological or pharmacological actions of vanadium; hence, it is difficult to reach any definitive conclusion concerning its biological significance, essentiality and its role in pathological states. An attempt has been made in this review to broadly document what is known of various biological actions of vanadium.