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Biomedical subjects

G Newlands

Publications and source records attributed to G Newlands.

17 recordsLinked to original sources
PubMed1997

Molecular cloning and characterisation of a developmentally regulated putative metallopeptidase present in a host protective extract of Haemonchus contortus.

Antisera from lambs immunised with the Haemonchus contortus integral membrane protein complex, Haemonchus galactose-containing glycoprotein (H-gal-GP), the lambs being refractory to subsequent challenge, were used to identify several clones from an adult H. contortus lambda gt11 cDNA library. Using gene-specific oligonucleotide primers in conjunction with primers directed to a conserved nematode Spliced Leader (SL) sequence and to the polyA+ tail of mRNA, the remaining 5' and 3' sequences of one of these clones, metallopeptidase-1 (MEP1), were amplified. The 2.4 kb full-length coding sequences was subsequently amplified in a single reaction. Sequence analysis identified MEP1 as encoding a putative zinc metallopeptidase, which shared limited homology with the mammalian type II integral membrane protein neutral endopeptidase (NEP). Southern blotting indicated that MEP1 belonged to a multigene family. MEP1 was expressed in bacteria as a glutathione-S-transferase (GST) fusion protein, and a specific antiserum raised in sheep. This antiserum recognised several polypeptide components of H-gal-GP. Immunolocalisation studies showed that MEP1 encoded a protein located on the luminal surface of the nematode gut. Both MEP1 mRNA and protein are developmentally regulated with expression being limited to the blood-feeding stages of H. contortus.

Amino Acid Sequence↗
PubMed1993

Localization of rat tryptase to a subset of the connective tissue type of mast cell.

We examined the cellular distribution of rat tryptase in rat skin, lung, small intestine, and peritoneal lavage cells by immunohistochemical techniques. Tryptase purified to apparent homogeneity from rat skin was used to generate a goat polyclonal anti-rat tryptase antibody. Tryptase-containing cells were detected in lung, skin, and peritoneal lavage cells. Small intestine mucosa, on the other hand, showed few if any tryptase-positive cells. Sequential staining with Alcian blue and anti-tryptase antibody showed that tryptase is located only in mast cells. Sequential staining with safranin to identify the connective tissue type of mast cell and anti-tryptase antibody showed that tryptase resides only in this mast cell type. However, only a subpopulation of the safranin-stained mast cells contained tryptase. In lung, 53% of the mast cells stained with safranin; 94% contained tryptase. In skin, 80% stained with safranin; only 6% contained tryptase. In peritoneal cells, more than 95% of the mast cells were stained with safranin; 20% contained tryptase. In the bowel mucosa, where few cells are stained by safranin, no cells with tryptase were detected. The percentages of cells with chymase I that also contained tryptase were 80% and 84% for lung, 4% and 7% for skin, and 15% and 13% for peritoneal cells by respective simultaneous and sequential double labeling with anti-tryptase and anti-chymase I antibodies. This study suggests that the rat connective tissue type of mast cell is subdivided into two forms on the basis of the presence or absence of tryptase, whereas rat mucosal mast cells lack this enzyme. These results contrast with those in humans, in which tryptase is present in all mast cells, but are similar to mice, in which tryptase mRNA has been detected only in the connective tissue type.

Animals↗
PubMed1990

Behavioural and epidemiological considerations pertaining to necrotic araneism in southern Africa.

Species of three spider genera are known to cause dermonecrotic lesions in man. The incidence of necrotic araneism caused by species of these genera is a function of their behaviour and their geographical distribution in relation to areas of high human population density. Evidence based on an analysis of 39 diagnosed spider bites suggests that sac spiders (Chiracanthium sp.) are responsible for most spider bites, followed by violin spiders, Loxosceles sp.

Africa, Southern↗
PubMed1990

A key for the clinical diagnosis of araneism in Africa south of the equator.

A simple key that will enable the clinician to diagnose the culprit species in cases of spider bite in Africa south of the equator in the absence of the culprit is presented. Species of four spider genera are responsible for virtually all the cases of araneism requiring medical attention, viz. Latrodectus, Chiracanthium, Loxosceles and Sicarius. The signs and symptoms at various intervals following envenomation by these spiders are sufficiently distinctive to allow specific diagnosis in most cases. To make this more easily possible the signs and symptoms at various intervals after envenomation have been tabulated in the form of a diagnostic key.

Africa, Southern↗
PubMed1988

Review of southern African spiders of medical importance, with notes on the signs and symptoms of envenomation.

Medically important spiders in southern Africa are discussed in terms of their morphological features and distribution, the signs and symptoms of envenomation and the possible treatment thereof. A simple pictorial key is provided to enable the non-specialist to identify the neurotoxic and cytotoxic species. The following spiders are now known to be medically important in southern Africa: Latrodectus indistinctus (neurotoxic), Chiracanthium lawrencei (cytotoxic), Loxosceles sp. (cytotoxic) and Sicarius sp. (cytotoxic - haemotoxic).

Animals↗
PubMed1987

Clinical, biochemical and pathological study of perinatal lambs in a commercial flock.

The birth and fate of 818 lambs born to 571 ewes on a low-ground farm in the Scottish Borders with a history of substantial perinatal mortality were monitored with a range of physiological, biochemical and pathological measurements. In lambs which survived, the rectal temperature, birthweight and plasma concentrations of fructose, insulin, thyroxine and the third component of complement at birth, and the weight at four months of age, decreased with litter size. One hundred and thirty-seven lambs were stillborn or died within four days and seven others died later. The mothers of 77 per cent of these lambs had low condition scores, but the lamb deaths did not correlate significantly with the condition scores. From data relating to birthweight, temperature, packed cell volume and plasma composition it was deduced that placental insufficiency was involved in 24 per cent of these deaths; acute hypoxaemia at birth accounted for 35 per cent, inadequate thermogenesis for 12 per cent and starvation for 13 per cent. The remaining 16 per cent of dead lambs could not be assigned to any of these categories. Using only clinicopathological criteria, 37 per cent of the lamb deaths were attributed to antenatal influences which included immaturity, developmental anomalies, and degenerative or inflammatory changes. Thirty-three per cent of the deaths were due to post natal factors which included, in declining order of frequency, starvation, enteritis, misadventure, pneumonia, navel infections and septicaemia. No conclusions could be drawn from the pathological examinations alone in the remaining 30 per cent, although almost half of these had low rectal temperatures after birth, death being attributed to hypothermia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

The isolation and characterization of globule leucocytes: their derivation from mucosal mast cells in parasitized sheep.

Ovine mucosal mast cells and globule leucocytes have been isolated from the abomasum of normal sheep, and from animals challenged with Ostertagia circumcincta. The ultrastructural, morphological and histochemical properties of these cells have been investigated. The granules of ovine mucosal immunoglobulin and a serine esterase. These cells also possess surface immunoglobulin. Cells morphologically intermediate between mucosal mast cells and bulin. Cells morphologically intermediate between mucosal mast cells and globule leucocytes have similar granule and surface properties. These observations, together with quantitative data, indicate that alterations in the granule structure of mucosal mast cells as a consequence of prolonged antigenic challenge give rise to mast cells in the epithelium which, in the past, have been commonly recognized as globule leucocytes.

Abomasum↗
PubMed1983

Motorcycling morbidity and mortality--an unstudied epidemic.

South Africa has the highest motorcycle accident and associated casualty rate in the world. In dealing with the problem South Africa lags far behind other countries where rider training programmes have had astonishing success. Accident statistics, problems relating to motorcycling and protective clothing are discussed. Recommendations are made which if implemented should reduce the accident and casualty rate by at least 50%; this indicates the size of the problem in this neglected field of automotive preventive medicine.

Accidents, Traffic↗
PubMed1983

Systemic release of mucosal mast-cell protease in primed rats challenged with Nippostrongylus brasiliensis.

The systemic secretion of a serine protease, rat mast-cell protease II (RMCPII), a major product of rat mucosal mast cells (MMC), was measured by a sensitive enzyme-linked immunosorbent assay (ELISA) in the sera of naive and primed rats challenged with the nematode N. brasiliensis. The systemic secretion of RMCPII was both time- and dose-dependent in primed rats (1-3 micrograms RMCPII/ml serum, 1 hr after challenge). Systemic release of RMCPII was slower and less pronounced in naive rats following intraduodenal challenge with 5-day-old worms. No RMCPII was detected in the sera of naive rats challenged with 4-day-old N. brasiliensis. Soluble worm antigen had no effect in naive rats, but when it was given intraduodenally or intravenously to primed rats, the serum levels of RMCPII 1 hr later were 10.5 micrograms/ml and 122 micrograms/ml, respectively. Few morphological changes were detected in MMC following worm challenge and the jejunal content of RMCPII was unaltered. A substantial reduction in the number of MMC occurred following intravenous injection of worm antigen, and the remaining cells were vacuolated and pale-staining, although granule exocytosis was not observed. Significant reduction in the jejunal content of RMCPII was also evident. These results demonstrate, unequivocally, that MMC are activated in response to N. brasiliensis challenge infection or to parasite antigens. In addition, the ability to detect secreted RMCPII in the sera of test animals provides a highly sensitive and uniquely selective assay to determine the participation of MMC in pathological reactions at mucosal surfaces.

Animals↗
PubMed1983

Immune exclusion, a mechanism of protection against the ovine nematode Haemonchus contortus.

The fate of exsheathed Haemonchus contortus larvae injected directly into the abomasal lumen was studied in groups of naive and hyperimmune sheep. Within 48 hours of challenge, more than 90 per cent of the larvae were lost from hyperimmune sheep. The larvae had a propensity to associate with the superficial mucus in both groups and, in naive sheep, approximately 50 per cent of the larvae entered glandular tissue within four hours of challenge. By contrast, although initially associated with the mucosal surface, larvae in immune sheep were excluded from the glandular tissues. It is postulated that the rapid loss of worms from the hyperimmune abomasum is a consequence of 'immune exclusion' and the possible mechanisms underlying this process are discussed.

Abomasum↗
PubMed1982

Loxoscelism in the Transvaal, South Africa.

Bites by spiders of the genus Loxosceles have been implicated as a cause of necrotic arachnidism in the Transvaal. The identification and natural history of three species of Loxosceles common in the Transvaal, L. spinulosa, L. speluncarum and L. parrami, are discussed, the clinical symptoms of envenomation as observed both in human patients and in experimental animals are presented, and the histopathological appearance of the lesion, at different stages of its development, is described.

Animals↗
PubMed1981

Mannosidosis in Aberdeen Angus cattle in Britain.

Mannosidosis, an inherited and lethal lysosomal storage disease of Aberdeen Angus cattle, was diagnosed on a farm in north-east Scotland. Two affected calves were examined in detail. Both were poorly grown and ataxic, though the intention tremor and aggression considered characteristic of the disease were not recorded. Histological examination revealed typical vacuolation of nerve cells, fixed macrophages and epithelial cells of the viscera. Deficiency of the enzyme alpha mannosidase was demonstrated. The epidemiology of the disorder in Scotland is considered and control methods indicated.

Animals↗
PubMed1981

Wandering spider bite--much ado about nothing.

The wandering spider, Palystes natalius, has been regarded as medically important since 1959. Simple experiments recently conducted suggest that serious misinterpretations of an observed result were responsible for this misconception.

Animals↗
PubMed1980

Cutaneous necrosis caused by the bite of Chiracanthium spiders.

Spiders of the genus Chiracanthium are very common in and about homes in southern Africa. The bite of this spider results in cutaneous necrosis. The clinical and histopathological features and the natural history and identification of these spiders are discussed briefly.

Animals↗
PubMed1978

Review of Southern African scorpions and scorpionism.

Medically important scorpions are discussed in terms of their venom, methods of envenomation and distribution in relation to the pattern of human population density dispersal. Notes on the treatment of scorpion sting and the identification of important species are provided.

Animals↗
PubMed1975

Review of the medically important spiders in Southern Africa.

Known and suspected medically important Southern African spiders are reviewed in terms of their distribution, identification, action of the venom and treatment of the bite. Simple diagnostic characteristics of each species are provided to assist the non-specialist in identifications.

Africa, Southern↗