Michael S. Clegg

Influence of ashing techniques on the analysis of trace elements in animal tissue - I. Wet ashing

A multitude of methods exists at present for the solubilization of biological tissues for atomic absorption analysis. We have examined several common methods of wet ashing using NBS bovine liver in order to determine which acids, acid combinations, or bases should be used as digesting agents for accurate and precise measurement of iron, copper, zinc, and manganese. Nitric acid proved to be the most effective wet ashing agent. With nitric acid, mean concentrations for iron, copper, and zinc differed from NBS certified values by less than 1.5% while those for manganese differed by 4%.

Copper, lysyl oxidase, and extracellular matrix protein cross-linking

Protein-lysine 6-oxidase (lysyl oxidase) is a cuproenzyme that is essential for stabilization of extracellular matrixes, specifically the enzymatic cross-linking of collagen and elastin. A hypothesis is proposed that links dietary copper levels to dynamic and proportional changes in lysyl oxidase activity in connective tissue. Although nutritional copper status does not influence the accumulation of lysyl oxidase as protein or lysyl oxidase steady state messenger RNA concentrations, the direct influence of dietary copper on the functional activity of lysyl oxidase is clear. The hypothesis is based on the possibility that copper efflux and lysyl oxidase secretion from cells may share a common pathway. The change in functional activity is most likely the result of posttranslational processing of lysyl oxidase. Copper is essential for organic cofactor formation in amine oxidases such as lysyl oxidase. Copper-containing amine oxidases have peptidyl 2,4,5 tri(oxo)phenylalanine (TOPA) at their active centers. TOPA is formed by copper-catalyzed oxidation of tyrosine, which takes place as part of Golgi or trans-Golgi processing. For lysyl oxidase, recent evidence (Science 1996;273:1078-84) indicates that as an additional step, a lysyl group at the active center of lysyl oxidase reacts with TOPA or its precursor to form lysyl tyrosylquinone.

The Plausibility of Micronutrient Deficiencies Being a Significant Contributing Factor to the Occurrence of Pregnancy Complications

Numerous studies support the concept that a major cause of pregnancy complications can be suboptimal embryonic and fetal nutrition. Although the negative effects of diets low in energy on pregnancy outcome are well documented, less clear are the effects of diets that are low in one or more essential micronutrients. However, several observational and intervention studies suggest that diets low in essential vitamins and minerals can pose a significant reproductive risk in diverse human populations. Although maternal nutritional deficiencies typically occur as a result of low dietary intakes of essential nutrients, nutritional deficiencies at the level of the conceptus can arise through multiple mechanisms. Evidence from experimental animals supports the concept that in addition to primary deficiencies, secondary embryonic and fetal nutritional deficiencies can be caused by diverse factors including genetics, maternal disease, toxicant insults and physiological stressors that can trigger a maternal acute phase response. These secondary responses may be significant contributors to the occurrence of birth defects. An implication of the above is that the frequency and severity of pregnancy complications may be reduced through an improvement in the micronutrient status of the mother.

Zinc deficiency‐induced cell death

Zinc deficiency is characterized by an attenuation of growth factor signaling pathways and an amplification of p53 pathways. This outcome is facilitated by hypo‐phosphorylation of AKT and ERK secondary to zinc deficiency, which are permissive events to the activation of the intrinsic cell death pathway. Low zinc concentrations provide an environment that is also conducive to the production of reactive oxygen/reactive nitrogen species (ROS/RNS) and caspase activation. Additionally, during zinc deficiency endogenous survival pathways such as NF‐κB are inhibited in their transactivation potential. The above factors contribute to the irreversible commitment of the zinc deficient cell to death. IUBMB Life, 57: 661‐670, 2005

Food diversity and drought survival. The Hausa example

Two Hausa villages in the Sahel of south-eastern Niger were surveyed for food procurement practices, with special focus on dietary use of wild plants. Activities and behaviours during years of adequate rainfall were compared to practices during drought. A diversified food base was maintained through hunting, gathering, agriculture, horticulture, and animal husbandry. Members of households surveyed (n = 112) foraged for edible wild plants located in bushlands adjacent to villages, within household compounds, or within agricultural fields. Dominant agricultural crops were beans, millet, peanuts, and sorghum; prominent household garden species were melon, okra, and squash. At the time of the survey most households experienced marginal crop yields. Edible wild plants were prominent in local diet during both drought and during years of adequate rainfall; more than 80 species were commonly consumed. Protein values of several wild plants exceeded 20%, including Amaranthus hybridus, Cassia occidentalis, Cenchrus ...

Mineral values of selected plant foods common to southern Burkina Faso and to Niamey, Niger, West Africa

Wild and cultivated fruits, leaves, nuts, seeds, spices and vegetables from southern Burkina Faso and Niamey, Niger, were analysed for their copper, iron, magnesium, manganese and zinc concentrations and compared to imported, exotic reference foods found within the study area. The species analysed covered a broad spectrum of local diet; 33 were wild and 16 were cultivated. The edible wild plants were often the highest in mineral concentrations. Five species analysed, exhibited consistently high mineral values, specifically, Adansonia digitata, Boerhavia diffusa, Cerathoteca sesamoides, Sclerocarya birrea and Xylopia sp. The latter was particularly high in zinc, an observation which suggests that there may be a solid rationale for local traditions which recommended its consumption during pregnancy and lactation. Respondents indicated that during times of drought, wild plants were not consumed in the volume they once were, due to changes of infrastructure and in famine relief programmes.

Developmental Consequences of Trace Mineral Deficiencies in Rodents: Acute and Long-Term Effects

Approximately 3% of infants born have at least one serious congenital malformation. In the U.S., an average of 10 infants per thousand die before 1 y of life; about half of these deaths can be attributed to birth defects, low birth weight or prematurity. Although the causes of developmental abnormalities are clearly multifactorial in nature, we suggest that a common factor contributing to the occurrence of developmental abnormalities is suboptimal mineral nutrition during embryonic and fetal development. Using zinc and copper as examples, evidence is presented that nutritional deficiencies can rapidly affect the developing conceptus and result in gross structural abnormalities. Deficits of zinc or copper can result in rapid changes in cellular redox balance, tissue oxidative stress, inappropriate patterns of cell death, alterations in the migration of neural crest cells and changes in the expression of key patterning genes. In addition to well-recognized malformations, mineral deficiencies during perinatal development can result in behavioral, immunological and biochemical abnormalities that persist into adulthood. Although these persistent defects can in part be attributed to subtle morphological abnormalities, in other cases they may be secondary to epigenetic or developmental changes in DNA methylation patterns. Epigenetic defects combined with subtle morphological abnormalities can influence an individuals risk for certain chronic diseases and thus influence his or her risk for morbidity and mortality later in life.

A decrease in intracellular zinc level precedes the detection of early indicators of apoptosis in HL-60 cells

Low extracellular zinc concentrations have been associated with the induction of apoptosis. To assess the relationship between intracellular zinc concentration and the rate of apoptosis, cells were grown in media containing 0.5, 25, or 50 μM zinc and analyzed by flow cytometry or fluorescence microscopy. Cells grown in 0.5 μM zinc medium over 48 h showed a successive decrease in intracellular zinc concentration measured by the zinc-specific fluorophore, zinquin. After 18 h in 0.5 μM zinc medium, rhodamine 123 retention decreased. However, the addition of 10 μM zinc to the 0.5 μM medium before 16 h in culture restored rhodamine retention in the cells. After 30 h there was an increase in the number of cells cultured in 0.5 μM zinc medium that bound annexin V-FITC. These data indicated that decreased intracellular zinc concentration preceded early markers of apoptosis, with alterations in mitochondrial transmembrane potential preceding the loss of polarity in the cell membrane.

Paraparesis, hypermanganesaemia, and polycythaemia: a novel presentation of cirrhosis

Progressive myelopathy is a rare complication of chronic hepatic disease which has never been reported in the paediatric age group. We describe the 11 year course of an adolescent male with hepatic myelopathy caused by cryptogenic micronodular cirrhosis. His condition has been associated with persistent polycythaemia and extraordinary increases of whole blood manganese, with magnetic resonance imaging evidence of manganese deposition within the basal ganglia and other regions of the brain. The patient has developed neither liver failure nor parkinsonism. The pathophysiological bases of this multiorgan system disorder are described.

Pathology of inherited manganese transporter deficiency.

We followed a patient with manganese transporter deficiency due to homozygous SLC30A10 mutations from age 14 years until his death at age 38 years and present the first postmortem findings of this disorder. The basal ganglia showed neuronal loss, rhodanine‐positive deposits, astrocytosis, myelin loss, and spongiosis. SLC30A10 protein was reduced in residual basal ganglia neurons. Depigmentation of the substantia nigra and other brainstem nuclei was present. Manganese content of basal ganglia and liver was increased 16‐fold and 9‐fold, respectively. Our study provides a pathological foundation for further investigation of central nervous system toxicity secondary to deregulation of manganese metabolism. Ann Neurol 2014;75:608–612