Total plasma magnesium in healthy and critically ill foals

Abnormalities in total Mg (tMg) concentration in plasma and/or serum are common in critically ill humans, and the association with increased mortality has been documented in several clinical studies in adults and newborns with hypoxic-ischemic encephalopathy. Abnormalities in tMg were studied in hospitalized dogs, cats, and adult horses. Newborn foals were scarcely studied with regard to Mg concentration. The aims of the present study were: (1) to compare two analytical methods for the determination of tMg in plasma: the automated colorimetric method and the atomic absorption spectrometry; (2) to measure plasma tMg in healthy foals during the first 72 hours after birth and in sick foals during the first 72 hours of hospitalization; (3) to compare total plasma Mg concentration among healthy foals, foals affected by perinatal asphyxia syndrome (PAS), prematurity and/or dismaturity, and sepsis; (4) to evaluate tMg plasma concentration in surviving and non-surviving foals. One hundred seventeen foals were included in the study: 20 healthy and 97 sick foals. The automated method used in clinical practice probably overestimates plasma tMg. Due to its higher sensitivity and specificity, the atomic absorption spectrometry should be considered the method of choice from an analytical point of view, but requires an instrumentation not easily available in any laboratory and specific technical skills and competencies. Plasma tMg in healthy foals were included in the range 0.52 to 1.01 mmol/L and did not show any time-dependent change during the first 72 hours of life. In sick foals, tMg evaluated at T0 was statistically higher than tMg measured at subsequent times. Foals affected by PAS had a tMg at T0 significantly higher (P < 0.01) than healthy, septic, and premature and/or dysmature foals. The t test found significantly higher (P < 0.01) plasma tMg measured at T0 in non-surviving than in surviving foals. Plasma tMg could be a useful parameter for the diagnosis of PAS and the formulation of the prognosis in critically ill foals.

Cadmium accumulation and antioxidant responses in Sparus aurata exposed to waterborne cadmium

Cadmium (Cd), a nonessential trace element, is rapidly accumulated by most living organisms and subsequently exerts its toxicity at different molecular levels. This study exposed gilthead sea bream (Sparus aurata) to waterborne 0.1 mg/l Cd for 11 days and investigated the Cd accumulation pattern, lipid oxidation, and response of antioxidant defences. At the end of the experiment, mean Cd concentrations in gills and liver, the organs most prone to metal accumulation, were 209.4 and 371.7 ng/g ww, respectively. Muscle did not show any Cd retention during the 11 days of exposure. In liver, the cytosolic fraction of the metal was chelated into the nontoxic form by metallothionein (MT), a specific Cd-inducible protein. Zn and Cu concentrations were not influenced by Cd exposure. Glutathione (GSH) concentrations and the antioxidant enzyme activities of GSH reductase and GSH peroxidase showed an overall decreasing trend. In addition, lipid and aqueous hydroperoxide levels did not show any significant variation. Oxidative stress indirectly generated by Cd seems to be compensated for by the different biochemical systems tailored to decrease cellular damage. In particular, the negative effects of Cd accumulation in tissues were probably counteracted by the induction of MT.

Copper transporter 1, metallothionein and glutathione reductase genes are differentially expressed in tissues of sea bream (Sparus aurata) after exposure to dietary or waterborne copper

The high affinity copper transporter 1 (Ctr1), metallothionein (MT) and glutathione reductase (GR) are essential for copper uptake, sequestration and defense respectively. Following rearing on a normal commercial diet (12.6+/-0.2 mg kg(-1) Cu), sea bream were fed an experimental control diet lacking mineral mix (7.7+/-0.3 mg kg(-1) Cu), an experimental diet enhanced with Cu (135+/-4 mg kg(-1) Cu) or an experimental diet (7.7+/-0.3 mg kg(-1) Cu) whilst exposed to Cu in water (0.294+/-0.013 mg L(-1)). Fish were sampled at 0, 15 and 30 days after exposures. Fish fed the Cu-enhanced experimental diet showed lower levels of expression of Ctr1 in the intestine and liver compared to fish fed control experimental diets, whilst Ctr1 expression in the gill and kidney was unaffected by excess dietary Cu exposure. Waterborne-Cu exposure increased Ctr1 mRNA levels in the intestine and the kidney compared to experimental controls. Excess dietary Cu exposure had no effect on levels of metallothionein (MT) mRNA, and the only effect of dietary excess Cu on glutathione reductase (GR) mRNA was a decrease in the intestine. Both MT mRNA and GR were increased in the liver and gill after waterborne-Cu exposure, compared to levels in fish fed experimental control low Cu diets. Thus, Ctr1, MT and GR mRNA expression in response to excess Cu is dependent on the route of exposure. Furthermore, the tissue expression profile of sea bream Ctr1 is consistent with the known physiology of copper exposure in fish and indicates a role both in essential copper uptake and in avoidance of excess dietary and waterborne copper influx.

Effect of different organotins on DNA of mollusk (Scapharca inaequivalvis) erythrocytes assessed by the comet assay

The alkaline comet assay, employing a single-cell gel-electrophoresis, is a rapid, simple and sensitive technique for visualizing and measuring DNA damage leading to strand breakage in individual cells. In this study, we report data about the effect of different organotin compounds (MBTC, DBTC and TBTC) on DNA from erythrocytes of the Scapharca inaequivalvis bivalve mollusc. Our results show significant DNA damage after 30 min in vitro incubation with 10microM of organotins. Since TBTC turned out to be the most genotoxic compound, followed by MBTC and DBTC, we exposed the molluscs to 50ppb of TBTC for 11 days. A significant increase of comet parameters was measured in our experimental conditions. The use of the comet test as a high-throughput screening assay to monitor the effect of environmental pollutants on marine organisms has been proposed.

Clinical and pathological findings of acute zinc intoxication in a puppy

This report describes the clinical and pathological findings in a case of acute zinc poisoning in a young dog. The puppy suffered four days of progressively more severe vomiting and diarrhoea. Jaundice and pale mucous membranes, severe haematemesis and haemoglobinuria were other findings. Despite intensive therapy, the dog died a few hours after hospitalisation. Postmortem examination revealed a metallic foreign body in the stomach, catarrhal gastritis, hepatomegaly and enlarged, dark kidneys. Histology showed hepatic centrilobular vacuolar degeneration, haemoglobinuric nephrosis with early tubular necrosis, haemosiderosis and extramedullary haematopoiesis, as well as neuronal damage. The foreign body was mainly composed of zinc. Plasma zinc values were markedly raised (34.5 microg/ml; normal range 0.8 to 1.0 microg/ml). Pathophysiological mechanisms of zinc poisoning are discussed.

Immune-endocrine status and coeliac disease in children with Down's syndrome: relationships with zinc and cognitive efficiency

Immune defects, thyroid abnormalities, plasma zinc levels, and the presence of gastrointestinal disease were investigated in 43 children with Down's syndrome (DS). Peripheral T lymphocytes with the phenotype of helper cells or cluster of differentiation 4 (CD4) were decreased. Circulating activated T cells (CD3/HLA-DR-positive cells) and large granular lymphocytes (CD16/CD56 positive cells) were increased. Plasma levels of interleukin-6 were higher in DS children than in controls. Serum levels of thyroid-stimulating hormone were increased in DS. Coeliac disease was over-represented in the group of DS children and many of these children also showed increased serum levels of immunoglobulin-G (IgG) specific for gliadin antigen. The increment of serum interleukin-6 was age-related and correlated with anti-gliadin IgG levels in DS. Plasma zinc levels were lower in DS children with coeliac disease and in those with anti-gliadin IgG than in DS without detectable anti-gliadin IgG. Dietary antigens may represent a continuous stimulus for the immune system in this syndrome and interfere with normal immune responses. Altered intestinal absorption of nutrients may in turn affect endocrine functions, brain development, and cognitive performances.

Metallothioneins (MTs) in marine molluscs

The presence of MTs in marine molluscs was firstly hypothesized in oyster and in mussel during the seventies, however mussel's and oysters' MTs were completely purified and sequenced rather later. Already from the first studies it was evident that the purification of molluscan MTs was more difficult than in mammals. Mussel's MTs are characterized by the presence of a monomeric and a dimeric form. Several physiological and biochemical parameters can influence the concentration and the isolation of MT from molluscan tissues. Remarkable variations in MT isolation and quantification might depend on the purification and storage protocol. Because of possible artefacts due to the isolation procedure the establishment of a standard protocol for MT quantification in marine mollusc is still an important goal. In a few species the presence of very low molecular weight metal binding ligands has also been reported, in these cases it cannot be excluded that the native MT has been cleaved by the action of proteases. This review aims to report: 1) importance of a standard method for MT purification and quantification in molluscs; 2) distribution of MT among molluscan species; 3) data concerning oyster's and mussel's MTs which are the two more deeply investigated marine molluscs; 4) biotic and abiotic factors influencing MT concentration, and 5) biological role of MT and use of MT as a biochemical marker of heavy metal pollution.

Seasonal changes of zinc, copper, and iron in gilthead sea bream (Sparus aurata) fed fortified diets

Four groups of gilthead sea bream (Sparus aurata) were fed diets with additional metal contents: a basal diet (diet A) contained Zn at 60.9 +/- 1.9 mg/kg diet, Cu at 3.9 +/- 0.9 mg/kg diet, and Fe at 138.3 +/- 6.8 mg/kg diet; the other diets were supplemented with copper (20 mg/kg, diet B), iron (100 mg/kg, diet C), or zinc (300 mg/kg, diet D). Two consecutive year-classes (0+ and 1+ age fish) from the same parent stock were examined. Several fish tissues were analyzed for metal contents in five different periods of each year in order to determine (1) the sensitivity of certain tissues as indicators of trace element metabolism and (2) possible seasonal variations. Growth data were similar for gilthead sea bream fed the basal diet and the metal-fortified diets. Mineral concentrations in tissues were found to be little affected by the dietary supplementation of trace elements, suggesting an efficient homeostatic control of these three metal concentrations. Tissues involved in metal metabolism (e.g., liver, kidney, gills) presented greater variations between minimum and maximum values with respect to other tissues (e.g., brain, muscle, eye). Seasonal variations were observed during the 2 yr of this study and were especially evident for zinc and copper concentrations in the liver. The overall pattern of metal variations showed a decreasing trend during the 2 yr. Results from this study indicate that (1) trace element concentrations in fish tissues vary with age and life cycle and (2) trace element requirements may vary in function of age and life cycle.

Heavy metals in some species of waterfowl of northern Italy

Concentrations of heavy metals (zinc, copper, cadmium, and iron) were measured in several tissues (brain, gizzard, leg-muscle, heart, breast-muscle, intestine, liver and kidney) of moorhens (Gallinula chloropus), black-headed gulls (Larus ridibundus), and coots (Fulica atra) collected between autumn 1985 and spring 1989 in northern Italy. Cadmium concentrations in the liver and kidney of water-rails (Rallus aquaticus) and in five species of Anatidae collected also were measured. High mean (+/- SD) copper levels were detected in aerobic muscles such as heart (38 +/- 5 micrograms/g dry weight (DW)) and pectoral muscles (35 +/- 7 micrograms/g DW). Compared to other tissues, the iron content of brain was rather low and constant, with a mean value of 160 +/- 17 micrograms/g DW in moorhens, 157 +/- 60 micrograms/g DW in black-headed gulls, and 157 +/- 25 micrograms/g DW in coots. Iron concentrations in tissues of moorhens from the Reno River were significantly higher than those from the Sile River. Cadmium was detectable only in the liver and kidney; there was a linear relationship between cadmium levels in these two organs. The highest mean (+/- SD) cadmium concentrations were present in the kidney of black-headed gull (30 +/- 20 micrograms/g DW).

Plasmic levels of trace elements and immune functions in the healthy elderly

Healthy elderly persons were selected according to an admission protocol which included clinical, hematological and biochemical parameters. Plasmic levels of zinc in these subjects were in the normal range, while plasmic copper was higher than that of young controls. The number of circulating lymphocytes and CD3+ cells was decreased; however, the absolute number of CD4+, CD8b, CD8d, CD20+ and CD57+ cells did not differ from that of controls. A decreased lymphocyte response to PHA in serum-free medium cultures was also observed in the healthy elderly persons.

Cadmium induction of renal and hepatic ornithine decarboxylase activity in the rat. Effects of sex hormones and involvement of the renin-angiotensin system

We investigated the effect of sex hormones on the sex-dependent response of rat kidney ornithine decarboxylase (ODC) activity to cadmium (Cd) administration and the involvement of the renin-angiotensin system in mediating stimulation of the liver enzyme by the metal. The response of renal ODC to Cd, which occurs in intact adult males but not in females, is also detectable in prepubertal and castrated males. Upon treatment with 17 beta-estradiol, the basal levels of enzyme activity in intact or castrated adult males were enhanced and Cd administration failed to increase them further. In adult females the kidney enzyme became responsive after ovariectomy. Also, in prepubertal females renal ODC was induced by Cd, and this was prevented by treatment with 17 beta-estradiol. Under the same conditions, changes in the levels of Cd accumulation within the kidney, that might account for variations in the response of ODC activity, did not occur. Cd caused an increase in renin activity starting minutes after its injection. Captopril, which specifically inhibits the conversion of angiotensin I to angiotensin II, prevented completely the induction of liver ODC by this metal; stimulation of the enzyme by Co was not affected by the drug. A similar inhibitory effect was exerted by propranolol. Adrenalectomy had no influence on the response of hepatic ODC to Cd; the decarboxylase was unaffected by aldosterone administration. It is suggested that Cd may induce liver ODC through the increase in angiotensin II following stimulation of renin by the metal.

Comparative study of myosins present in the lateral muscle of some fish: species variations in myosin isoforms and their distribution in red, pink and white muscle

Myosin isoforms and their distribution in the various fibre types of the lateral muscle of eight teleost fish (representing a wide range of taxonomic groups and lifestyles) were investigated electrophoretically, histochemically and immunohistochemically. Polyclonal antisera were raised against slow (red muscle) and fast (white muscle) myosins of the mullet, and used to stain sections of lateral muscle. Antisera specific for fast and slow myosin heavy chains only (anti-FHC and anti-SHC respectively) and for whole fast and slow myosins (anti-F and anti-S respectively) were obtained, and their specificity was confirmed by immunoblotting against electrophoretically separated myofibrillar proteins. The ATPase activity of myosin isoforms was examined histochemically using methods to demonstrate their acid- and alkali-lability and their Ca-Mg dependent actomyosin ATPase. As expected, the predominant myosin (and fibre) type in the red muscle showed an alkali-labile ATPase activity, reacted with the anti-S and anti-SHC sera (but not anti-F or anti-FHC) and contained two 'slow' light chains, whereas the predominant myosin (and fibre) type in the white muscle showed an alkali-stable ATPase activity, reacted with anti-F and anti-FHC sera (but not anti-S or anti-SHC) and contained three 'fast' light chains. However, superimposed upon this basic pattern were a number of variations, many of them species-related. On analysis by two-dimensional gel electrophoresis fish myosin light chains LC1s, LC2s and LC2f migrated like the corresponding light chains of mammalian myosins, but fish LC1f consistently had a more acidic pI value than mammalian LC1f. Fish LC3f varied markedly in Mr in a species-related manner: in some fish (e.g. eel and mullet) the Mr value of LC3f was less than that for the other two light chains (as in mammalian myosin), whereas in others it was similar to that of LC2f (e.g. cat-fish) or even greater (e.g. goldfish). Species differences were also seen in the relative intensity of LC1f and LC3f spots given by the fish fast myosins. In most of the fish examined the red muscle layer showed some micro-heterogeneity, containing (in addition to the typical slow fibres) small numbers of fibres with a histo- and immunohistochemical profile typical of white muscle (fast) fibres. However, other immunohistochemically distinct minority fibres were found in the red muscle of the goldfish. Three types of pink muscle were distinguished: a mosaic of immunohistochemically typical red and white fibres (e.g. grey mullet).(ABSTRACT TRUNCATED AT 400 WORDS)

Myofibrillar ATPase activity of lateral muscle from the catfish and mullet

The histochemical and biochemical myofibrillar ATPase activities of red and white muscle of the catfish and mullet have been investigated. The histochemical reactions confirmed the typical pattern of red and white muscle and the absence of growing fibers in the white muscle of the mullet. Biochemical assay were used to determine the ATPase activity of red and white muscle myofibrils. Ratios of white muscle activity/red muscle activity were found to 2.2 in the mullet and 2.3 in the catfish. The myofibrillar ATPase activity of mullet was less thermostable than that of catfish but is still in the range for fish leaving in warm waters.

The tensor tympani muscle of cat and dog contains IIM and slow-tonic fibres: an unusual combination of fibre types

Using recently developed highly specific antisera to the full range of known adult mammalian skeletal muscle myosins, an immunohistochemical and histochemical examination was made of the middle ear muscle tensor tympani in the dog and cat. Approximately half the fibres were of the IIM type and there was a substantial population of apparently slow-tonic fibres, both these types being rare in mammals. In addition, some type I but no IIA nor IIB fibres were detected. Moreover, as no multiple end-plate innervation, thought to be typical of slow-tonic fibres, could be demonstrated in this muscle by acetylcholinesterase staining or by Ruffini gold impregnation, it is suggested that in tensor tympani the slow-tonic fibres are focally innervated. The very short length of the fibres, only 1-2 mm, is probably sufficient to permit adequate depolarization of a whole fibre by a single centrally situated end-plate. The functional implications of this combination of very rare fibre types in tensor tympani are unclear at present.

Preparation of type-specific antimyosin antibodies and determination of their specificity by biochemical and immunohistochemical methods

This paper reports the preparation of specific anti-slow myosin antibodies (anti-I) and anti-fast myosin antibodies (anti-IIA) raised against myosins from sheep and guinea pig masseter muscles. The specificity of the antibodies has been studied by immunodiffusion in agar and by the GEDELISA test using slow-twitch (type I), fast-twitch red (type IIA) and fast-twitch white (type IIB) myofibrils isolated from guinea pig muscles. The principal specificity of the anti-I and anti-IIA antibodies was for the heavy chains of type I and IIA myosins, respectively. A smaller reaction with the corresponding light chains was also detected. Immunohistochemical staining of muscle sections using these antibodies confirmed their fibre type specificity.

A comparative histochemical study of fibre types in middle ear muscles

Images

[Extraction and purification of slow myosin from the masseter muscle of Ovis aries]

Ovis aries masseter is a typical muscle consisting of slow-twitch fibres. The muscle homogeneity is well evidenced histochemically by the myosin ATPase reaction. The extraction and purification of myosin from sheep masseter is reported. After its centrifugation and dialysis followed by ion-exchange chromatography, the protein analysed on SDS polyacrylamide gels showed the usual pattern of slow myosin. The light-chain LC2 was present as a double band, a fact which has already been reported and which could be ascribed to SH group oxidation. From the present data sheep masseter can be considered a good source of slow myosin, and we have used it satisfactorily in the preparation of specific antibodies.

No classical type IIB fibres in dog skeletal muscle

To analyse the fibre type composition of adult dog skeletal muscle, enzyme histochemistry, immunohistochemistry for type I, IIA and IIB myosins, and peptide mapping of myosin heavy chains isolated from typed single according to the activity of the m-ATPase after acidic and alkaline preincubation proved to be rather difficult and was only consistently achieved after a very careful adjustment of the systems used. One of these sub-classes of type II fibres stained more strongly for m-ATPase activity after acidic and alkaline preincubation, was oxidative-glycolytic and showed a strong reaction with an anti-type IIA myosin. The other one, however, although showed a faint reaction with an anti-type IIB myosin. Peptide mapping of the myosin heavy chains of typed single fibres revealed two populations of heavy chains among the type II fibre group. Thus, in dog muscle, we are confronted with the presence of two main classes of type II fibres, both oxidative-glycolytic, but differing in the structure of their myosin heavy chains. In contrast to some reports in the literature, no classical type IIB fibres could be detected.

[Effect of cadmium on the activity of alkaline phosphatase (3.1.3.1) of Venus gallina]

The marine mollusc Venus gallina was exposed to 32 days sublethal concentrations of Cadmium (0.1 microliter/ml). The activity of alkaline phosphatase was assayed every four days. In the controls the activity was also tested in different tissues and in the soft tissue for the pH dependence. Moreover the influence of direct addition of 10(-4) M Cd on enzyme preparation in vitro was assayed. From the results there are no consistent relationships between the direct in vitro effects of the metal on the enzyme, that is inhibitory, and the effect of exposing the whole animal to the same metal, in this case no inhibition was observed.

[Dehalogenation of pp'DDT to pp'DDD in the liver microsomal fraction of Mugil cephalus]

pp'DDT was converted to DDD 1-1 dichloro-2,2 bis (p-chlorophenyl) ethane, by treated 12 000 x g supernatant preparations from grey mullet livers. The anaerobic reductive dechlorination occurs whether or not exogenous NADPH and riboflavin is added after a heat pretreatment, otherwise the dechlorination is lowered when the cofactors are not added.

[Cadmium binding and zinc variations in Mytilus galloprovincialis]

The accumulation of Cadmium in Mytilus galloprovincialis during a 18 days exposure period was studied. Cadmium content of the mantle, viscera, gills increased throughout the time. The study of the distribution of Cd in homogenates of mussels chronically intoxicated has shown that the metal is principally bound to low mol. wt. proteins similar to metallothioneins. Mytilus galloprovincialis metallothioneins are also comparable to the vertebrate proteins, suggesting a biological function ubiquitous in the living world.