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Biomedical subjects

J R Edwards

Publications and source records attributed to J R Edwards.

At least 109 records · Page 6Linked to original sources
PubMed1986

A progressive spinal myelinopathy in beef cattle.

Ataxia of the hind limbs in nine calves was associated with degenerative lesions in spinal white matter and neuronal chromatolysis in red nucleus, spinal grey matter and various nuclei of the medulla oblongata and cerebellum. The clinical signs and lesions were similar to those observed in enzootic ataxia of red deer and occurred predominantly in calves of the Murray Grey breed. The pathogenesis appears to involve a primary defect in central nervous system myelin with progressive myelin loss primarily in the spinal cord.

Animals↗
PubMed1985

The Pierre Robin syndrome reassessed in the light of recent research.

For many years clinicians have known the coincidental presentation of micrognathia, glossoptosis and cleft palate as the Pierre Robin syndrome. In conferences in 1974 and 1975 the term "Anomalad" was introduced which by definition is a primary malformation with superimposed secondary structural changes and the Pierre Robin syndrome became known as the Robin Anomalad. The concept was based on experimental observations available at that time. However, since that date further studies have demonstrated that administration of drugs to pregnant female rodents can produce coincidental failure of normal development of both mandible and palate. In the light of this work a critical review is made of the evidence upon which the mechanistic view of the condition evolved and an alternative hypothesis developed. From animal experimentation it can be argued that the nature of the condition is not mechanical and is more likely to be metabolic. Indeed, confirmatory evidence in man has recently been presented from Finland. If this is the case it may be erroneous to consider the Robin malformations as an "Anomalad" and mandibular maxillary agenesis would probably be a more accurate term.

Animals↗
PubMed1985

A survey of ovine dermatophilosis in Western Australia.

A random sample of 200 Merino sheep owners was interviewed by telephone during April 1983 and asked questions relating to the prevalence of ovine dermatophilosis in their flocks, methods used for prevention and treatment of dermatophilosis, management strategies employed and the location and annual rainfall of each farm. The response rate was 99.5%. During the previous 12 months 62.3% of farmers had observed dermatophilosis in their flocks. The prevalence within flocks was highest in hoggets (mean 2.2%, range 0 to 75%) followed by lambs (mean 0.8%, range 0 to 25%), ewes (mean 0.6%, range 0 to 20%) and wethers (0.2%, range 0 to 20%). The mean weight of wool identified as affected by dermatophilosis was 58 kg (range 0 to 882 kg). Preventive measures were used on 57% of farms and the most common methods were changes in dipping practice (23.6%) and culling of affected sheep (21%). An average of 13.7 sheep per farm were culled for dermatophilosis and of these, 82% were sold and the remainder (18%) were killed on the farm. Antibiotics, of which most were combinations of penicillin and streptomycin were used to treat dermatophilosis on 8.5% of farms and treatments other than antibiotics were used on 10% of farms. The prevalence of dermatophilosis and its relationship to various environmental and management factors varied with the age and sex of sheep. Discriminant analysis indicated that of the factors studied, average annual rainfall, month of lambing, average fibre diameter and the month ewes were shorn were related to the prevalence of dermatophilosis in lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1983

Inhibition of human lymphocyte activation by wheat germ agglutinin: a model for saccharide-specific suppressor factors.

The suppressive effect of wheat germ agglutinin (WGA) on lectin-stimulated blastogenesis and immunoglobulin production was studied. Addition of WGA at 10 micrograms/ml inhibited phytohemagglutinin (PHA)-, concanavalin-A (Con-A)-, and pokeweed mitogen (PWM)-induced mitogenic responses by 70-80%. PWM-driven immunoglobulin synthesis was suppressed by 45% with WGA. The inhibitory effects of WGA were not due to cell death or to interference with lectin binding at the cell surface. Inhibition was dependent on the presence of WGA in the cell culture during the first 24 hr of mitogen exposure and was observed in cultures of both monocyte-depleted peripheral blood mononuclear cells as well as T-cell-enriched populations. WGA-induced inhibition of blastogenesis was blocked by the addition of N-acetylglucosamine (GluNAc) which prevents WGA binding to the cell surface. WGA was found to mimic the suppressive effect of a soluble immune suppressor supernatant (SISS) derived from Con-A-activated mononuclear cell cultures. PHA responses were inhibited by 80 and 95% with SISS and WGA, respectively. The inhibition by both WGA and SISS was totally reversed with addition of GluNAc. Furthermore, WGA and SISS demonstrated competition for the same cell surface receptor site. WGA may therefore be useful as an in vitro model of a saccharide-specific, biologically relevant, soluble mediator for the investigation of mechanisms of immunologic suppression.

Cells, Cultured↗
PubMed1981

D-Glucosyltransferase of Streptococcus mutans: isolation of two forms of the enzyme that bind to insoluble dextran.

The D-glucosyltransferase from Streptococcus mutans 6715 has been separated into three enzymic fractions that differ in their binding to dextran and in their synthesis of dextran from sucrose. One enzymic fraction (AFF-I) does not bind to insoluble dextran, and it produces an insoluble D-glucan. Fraction AFF-IIU was eluted from a dextran affinity-column by either dextran or urea, whereas fraction AFF-IID was eluted only by dextran. Both of these fractions produce insoluble D-glucans from sucrose.

Chromatography, Affinity↗
PubMed1981

The effect of vitamin A on fusion of mouse palates. I. Retinyl palmitate and retinoic acid in vivo.

C57B1 mice were given orally one, two , or three doses of ritinyl palmitate or retinoic acid on day 11, 12, 13, or 14 or pregnancy to determine 1) if it was possible to produce cleft palate at any time during palatal development of the mouse embryo, and 2) the maternal and fetal levels of vitamin A associated with the production of clefts. Whereas a single dose of either substance was sufficient to cause clefts on day 11 or day 12, three doses at 3-hour intervals were necessary to cause clefts on day 14. Most of these clefts were incomplete. Measurement of vitamin A levels in maternal serum and fetuses of dams after administration of retinyl palmitate or retinoic acid on day 11 and day 14 of pregnancy showed that transplacental passage of retinyl palmitate, retinol, and retinoic acid had taken place. Analysis of fetal serum on day 14 showed increase in levels of retinyl palmitate, retinol, and retinoic acid after dosing with retinyl palmitate, and in retinoic acid alone after dosing with retinoic acid. In both cases peak levels were observed within 3 hours. Our findings suggest that the effect of vitamin A on the developing mouse palate is direct, occurring soon after its administration, and that duration of exposure is as important as its concentration in vivo. The apparent change in sensitivity of mouse palate between day 11 and day 14 of pregnancy is discussed.

Animals↗
PubMed1981

The effect of vitamin A on fusion of mouse palates. II. retinyl palmitate, retinol, and retinoic acid in vitro.

A fixed-exposure culture technique is described using palatal shelves removed from mouse fetuses on day 14 of pregnancy. In this technique growth is eliminated as a possible variable. The addition of retinyl palmitate, retinol, or retinoic acid to culture medium at concentrations similar to those found associated with cleft palates produced in vivo after dosing dams with vitamin A on day 14 prevented fusion of explanted shelves in vitro after a 24-hour exposure period. Retinoic acid prevented fusion of explants after as little as 4 hours exposure. Retinoic acid was more active in vitro than retinol, which was itself eight to ten times more active than retinyl palmitate. An explanation of the effect of vitamin A on the fusing mouse palate is give based on altered glycoprotein synthesis.

Animals↗
PubMed1980

Outpatient meniscectomy of the knee.

This paper reviews 218 patients who had outpatient meniscectomy at the University of Virginia between January 1974 and June 1977. Only one patient (0.46%) returned before his scheduled visit. Three patients (1.4%) had superficial wound infections. One (0.46%) had a pulmonary embolus several weeks postoperatively. Twelve percent underwent knee aspiration at two weeks after operation and 3.8% at six weeks. Twenty-seven patients had two meniscectomies at the University of Virginia, and 23 had both procedures as outpatients. None who had the first as an outpatient chose admission for the second. The average hospital bill for meniscectomy performed at a private hospital in Virginia in 1978 was +1,238.99. This would have been reduced by about 50% if meniscectomy had been done on an outpatient basis. In selected patients, outpatient meniscectomy can be done with a low complication rate, at a decreased cost, and with satisfaction to the patient and doctor.

Adolescent↗
PubMed1980

Isolation and characterisation of Bacteroides nodosus from foot lesions of cattle in Western Australia.

Thirty one isolates of Bacteroides nodosus were obtained from foot lesions observed on cattle at 3 abattoirs. All isolates were similar to the B. nodosus of ovine benign footrot (BFR) in their response to the degrading proteinase test. At one abattoir, where the interdigital lesions were examined in detail, 9 of 10 isolates were obtained from hyperkeratotic lesions with deep fissures. Traceback to 8 of the farms of origin which carried both sheep and cattle, revealed BFR in sheep on 4 farms. The significance of B. nodosus in interdigital lesions in cattle, and its possible pathogenicity, are discussed.

Animals↗
PubMed1980

Resistance of Haemonchus contortus to thiophanate.

The occurrence of a field strain of Haemonchus contortus which was resistant to thiophanate and susceptible to thiabendazole and levamisole is reported. The LD95 of thiophanate for the strain was found to be 156.1 mg/kg and its resistance factor was 6.7. In possessing specific thiophanate resistance it differed from previously reported thiophanate resistant strains of H contortus which have been benzimidazole resistant worms that have possessed cross resistance to thiophanate.

Animals↗
PubMed1979

Resolution of the glycosyltransferase activities from two strains of Streptococcus mutans by polyacrylamide gel electrophoresis in the presence of Tween 80.

The glycosyltransferase complex from Streptococcus mutans can be resolved by polyacrylamide gel electrophoresis following treatment with Tween 80. The enzyme complex was treated with Tween 80 and electrophoresis was performed in the presence of Tween 80. Discrete bands of glycosyltransferase activity were observed when the gels were incubated in buffered sucrose. The enzyme aggregation that occurs with the exocellular glycosyltransferase may involve lipophilic interactions that are disrupted by the Tween 80.

Electrophoresis, Polyacrylamide Gel↗