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Biomedical subjects

M J Clarkson

Publications and source records attributed to M J Clarkson.

At least 37 records · Page 2Linked to original sources
PubMed1994

Radiofrequency thermal angioplasty maintains arterial duct patency. An experimental study.

BACKGROUND: Long-term maintenance of arterial duct patency by a catheter technique would be a valuable nonsurgical method of palliation for duct-dependent circulations. We used a new method: percutaneous radiofrequency thermal balloon angioplasty of neonatal lamb arterial ducts. METHODS AND RESULTS: Radiofrequency balloons 5 or 6 mm in diameter were introduced via the femoral vein of 32 neonatal lambs and inflated to 4 atm. In 28, a radiofrequency generator was used to heat the saline/contrast mixture in the balloon to 65 degrees C (n = 2), 75 degrees C (n = 2), 85 degrees C (n = 10), 100 degrees C (n = 8), and 120 degrees C (n = 6). In 4 lambs, angioplasty alone was performed. Lambs were recatheterized to assess patency at intervals up to 78 weeks. Immediate results showed the arterial duct to be patent in all cases, with a mean rise in systolic pulmonary artery pressure of 13 +/- 8 mm Hg and a mean rise in pulmonary artery oxygen saturation of 12 +/- 15%. With a mean follow-up of 45.7 +/- 28 weeks, 3 of the 4 (75%) angioplasty alone ducts closed, but only 5 of the 28 (18%) radiofrequency-treated ducts (P < .05). The mean rise in oxygen saturation between the superior vena cava and the pulmonary artery was 7.6 +/- 7% at last follow-up. Follow-up angiography of the arterial ducts showed the development of stenoses in all patent ducts. CONCLUSIONS: Radiofrequency thermal balloon angioplasty leads to long-term arterial duct patency in lambs in > 80% of the treated group and is significantly more effective than balloon angioplasty alone.

Angioplasty, Balloon↗
PubMed1992

Farm investigations of anaemia in lambs caused by feeding cow colostrum.

The deaths on nine farms of lambs which had been fed cow colostrum as a substitute for ewe colostrum were investigated. Of 105 lambs which received cow colostrum, 65 (61.9 per cent) showed clinical signs of anaemia and 42 (40 per cent) died. The signs of anaemia usually appeared when the lambs were between eight and 12 days old. The most significant post mortem finding was the appearance of the bone marrow which was cream or grey rather than the normal bright red. The types of treatment which were given are summarised. Whey from samples of the colostrum fed to the lambs was tested for its effect on sheep red blood cells. Haemolysis or agglutination of the red cells occurred with some, though not all, of the samples which caused anaemia.

Anemia↗
PubMed1992

Culture of sheep Chlamydia in a sheep fibroblast cell culture.

Abortion and enteric isolates of Chlamydia psittaci from sheep differed in their growth in a fibroblastic cell culture derived from the small intestine of a lamb. Twenty abortion isolates, each from a different farm, produced large inclusions which could be passaged several times whereas 10 enteric isolates each from different farms (but from some of the farms of origin of the abortion isolates) produced sparse inclusions which could not be passaged. This appears to be a rapid method of distinguishing abortion and enteric isolates and may indicate different nutritional requirements or be related to the invasiveness of the isolates.

Abortion, Veterinary↗
PubMed1992

Antigenic and morphological differentiation of placental and intestinal isolates of Chlamydia psittaci of ovine origin.

Ewe placental and lamb intestinal isolates of Chlamydia psittaci recovered from flocks affected with ovine enzootic abortion were examined by inclusion morphology, indirect immunofluorescence (IIF) and immunoblot analysis. Chlamydiae recovered from the faeces of sheep from two flocks free of clinical disease were also examined. In cell culture ovine abortion (OA) and intestinal isolates were distinguishable by inclusion development and morphology. Similarly, in two-way IIF tests with one week mouse antisera isolates fell into two distinct groups: abortion or intestinal. Immunoblotting with convalescent sheep abortion antiserum identified 30 out of at least 40 silver staining polypeptides as antigenic both in OA and intestinal isolates. The serum produced a similar reaction pattern to the resolved proteins of each OA isolate, indicating a higher degree of antigenic conservation among these isolates. Considerable cross reactivity between the OA and intestinal isolates was identified, but the serum also showed apparent molecular weight differences between antigens of the two types in the 87-116 kDa, 38-44 kDa and 26-28 kDa regions. Furthermore, the immunoblotting analysis revealed heterogeneity among the intestinal isolates, particularly in antigens between 87-116 kDa and 38-44 kDa.

Abortion, Veterinary↗
PubMed1991

The growth and development of Echinococcus granulosus of sheep origin in dogs and foxes in Britain.

Four separate experiments were carried out by dosing dogs (Beagles and Border collies) and red foxes with protoscoleces obtained from hydatid cysts in sheep from mid-Wales. The dogs and foxes were killed at intervals over a period from 34-180 days after infection and the intestines were examined for Echinococcus granulosus. Border collie dogs were efficient hosts in that large numbers of worms developed, with gravid segments present by 55 days after infection; but Beagle dogs were poor hosts in that only small numbers of immature worms developed. Foxes were poor hosts in that few or no worms developed, but gravid segments were seen in three of 29 foxes. The worms showed morphological features similar to the 'sheep' rather than the 'horse' strain.

Animals↗
PubMed1990

Bovine immune recognition of Ostertagia ostertagi larval antigens.

Analysis of a detergent-solubilized somatic antigen of Ostertagia ostertagi 3rd stage larvae by SDS-PAGE and Western blotting has revealed two specific antigens with apparent molecular weights of 17 and 43 kD under reducing conditions. Probing of the Ostertagia ostertagi preparation with preinfection control sera has shown two cross-reacting antigens with apparent molecular weights of 67 and 81 kD. Both the 17 and the 43 kD antigens were recognised by IgG1 which was the predominant reactive subclass. FPLC fractionation of the crude extract with gel filtration and ion-exchange columns demonstrated immune reactivity in discrete peaks. Comparisons of ELISA and lymphocyte transformation showed antigenic components reactive with both antibodies and primed lymphocytes.

Animals↗
PubMed1990

Comparison of Albendazole and Praziquantel therapy of Echinococcus granulosus in naturally infected sheep.

The effects of albendazole (10 mg kg-1 day-1) and praziquantel (50 mg kg-1 day-1) for 6 weeks on naturally infected sheep with pulmonary cysts of Echinococcus granulosus of proven viability were studied. Immediately following therapy, one of three sheep treated with praziquantel had viable cysts and 7 months later one of two sheep had viable cysts. One sheep died during albendazole therapy, but 7 months following therapy only one of five sheep had viable cysts. Electron microscopy demonstrated necrotic germinal layer tissue in most albendazole-treated cysts and praziquantel also had an effect on cyst ultrastructure. These data suggest that recurrence in humans treated with albendazole may be small. Whilst praziquantel was not particularly effective in this animal model, its clear effect on the ultrastructure suggests that an increased dose and combination therapy with albendazole may be more effective.

Albendazole↗
PubMed1989

Ovine infectious keratoconjunctivitis: a microbiological study of clinically unaffected and affected sheep's eyes with special reference to Mycoplasma conjunctivae.

In a field survey of ovine infectious keratoconjunctivitis, the microbiological flora of 240 clinically unaffected eyes from sheep in 10 flocks was compared with the flora of an equivalent number of clinically affected eyes from 12 natural outbreaks of the disease. Totals of 16 and 17 genera of bacteria were recovered from unaffected and affected eyes, respectively. Staphylococcus, bacillus and branhamella were isolated significantly more often than the other genera of bacteria, in both the unaffected and affected eyes (P less than 0.05). Branhamella ovis and Escherichia coli occurred more frequently in affected eyes, and Staphylococcus aureus occurred more frequently in severely than mildly affected eyes. The genera Mycoplasma and Acholeplasma were isolated from both groups, and Mycoplasma conjunctivae occurred in 92 affected eyes (38.3 per cent), and 27 unaffected eyes (11.3 per cent).

Acholeplasma↗
PubMed1988

Experimental chemotherapy in horses infected with benzimidazole-resistant small strongyles.

The presence of benzimidazole-resistant strains of equine small strongyles was confirmed in horses at two properties in north west England by a series of faecal egg counts and larval cultures after treatment with mebendazole. A trail formulation of mebendazole in combination with piperazine citrate gave greater reductions in faecal egg counts than mebendazole alone but was much less effective than pyrantel embonate or dichlorvos.

Animals↗
PubMed1986

Toxoplasmosis in a flock of sheep: some investigations into its source and control.

Toxoplasmosis was thought to be a minor problem on a lowland sheep farm purchasing some 200 ewe lambs annually. Serological investigations and production records suggested a more substantial problem with most of the ewe lambs seroconverting during their first pregnancy, many while still at grass and receiving no supplementary food. Only 60 live lambs were produced per 100 ewe lambs tupped. It was known that cats occasionally inhabited the sheep houses, from which straw bedding was spread onto the pastures after lambing. Trials over two years with ewe lambs grazing either 'clean' or 'dirty' pastures indicated that the straw bedding was the most likely source of infection. Serial serological studies not only defined the time of infection but also showed that the ewe lambs could be kept free of infection and produce more live lambs; 58 live births came from 81 'clean' ewe lambs compared with 21 from 50 'dirty' ewe lambs.

Animals↗
PubMed1986

The epidemiology of hydatid disease in England and Wales.

The epidemiology of hydatid disease in man in England and Wales, based on the data collected between 1981 and 1983 at the Hydatid Reference Laboratory of the Public Health Laboratory Service, is presented. The incidence of hydatid disease was 42 cases per annum, with 2 cases per million population occurring in Wales and 0.2 per million in England. The highest prevalence was in London amongst the immigrant population. The incidence in the indigenous population was 15.5 cases per annum, with 5.6 cases per million occurring in South Powys, parts of South Wales and Herefordshire. The population most at risk is the rural, farming community in that area, but the West Midlands is also an apparent focus of the disease.

Adolescent↗
PubMed1985

Overview of bacterial infections of the skin and soft tissue and clinical experience with ticarcillin plus clavulanate potassium in their treatment.

The etiology, diagnosis, and treatment of skin and soft tissue infections are discussed, and the results of clinical experience with ticarcillin plus clavulanate potassium in these diseases at one clinic are reported. In a randomized and controlled clinical trial, the safety and effectiveness of ticarcillin plus clavulanate potassium and cefazolin were compared in the treatment of soft tissue infections in 20 patients. The 12 patients in the group treated with ticarcillin plus clavulanate potassium included 10 men and two women, with a mean age of 61 years; the eight patients in the group treated with cefazolin were five men and three women, with a mean age of 63.8 years. Ticarcillin plus clavulanate potassium was administered for four to 26 days (mean 12.5 days), and cefazolin for four to 20 days (mean 12 days). There were 29 evaluable pathogens in the group receiving ticarcillin plus clavulanate potassium and 22 in the group receiving cefazolin. Of the 29 pathogens in the former group, 22 were eradicated; three reinfections or superinfections occurred but were ultimately eradicated, and four pathogens persisted. Eighteen of the 22 pathogens in the cefazolin-treated group were eliminated and the other four persisted. Clinically, six of the 12 patients in the ticarcillin plus clavulanate potassium-treated group had cures, four showed improvement, and two failed to show a response. In the cefazolin-treated group, five of the eight patients had cures, one showed improvement, and two failed to show a response.

Aged↗
PubMed1985

Embryo transfer in sheep under practice conditions.

Embryo transfer was carried out on nine Texel donor ewes, one of them on two occasions, over two breeding seasons (1980 and 1981). The donors were prepared for superovulation on the farm by two different regimens and the recipients were also synchronised on the farm of origin. Surgery was carried out on donors and recipients at a veterinary practice and the techniques of anaesthesia, surgery and embryo transfer are described. Superovulation was variable and more than two ovulations were seen in only four of the 10 ewes. Forty-one corpora lutea were produced by the 10 ewes and 27 embryos were recovered. Twenty-one embryos were transferred to recipients and 14 lambs were produced. All the 10 donors except one produced lambs themselves. The value, economics and welfare aspects of the technique of embryo transfer under practice conditions are discussed and it is concluded that the procedure should not be carried out routinely but reserved for special circumstances.

Animals↗
PubMed1985

Vaccination of cows with clostridial antigens and passive transfer of clostridial antibodies from bovine colostrum to lambs.

Two Friesian cows were used to attempt to produce colostrum containing a high concentration of clostridial antibodies which could be fed to newborn lambs in order to passively transfer immunity to diseases caused by clostridia. One cow was given a commercial multicomponent clostridial sheep vaccine in two successive pregnancies and the second cow in one pregnancy. The first cow produced a low concentration of epsilon antitoxin (Clostridium perfringens, type D) in its blood and colostrum after the first course of three injections of vaccine. A higher concentration was produced by cow 2 after a course of six injections and by cow 1 after a further course of four injections in its next pregnancy. Two hundred ml of colostrum from cow 1 (after the second course of vaccine) was given to 12 newborn colostrum-deprived lambs. All showed a high concentration of antitoxin 48 hours later. The lambs were actively immunised by injections of the same clostridial vaccine at three and nine weeks or six and 12 weeks old and all produced sufficient antitoxin to protect up to slaughter at 24 weeks. It is concluded that colostrum from cows vaccinated with sheep clostridial antigens can be fed to protect lambs passively.

Animals↗
PubMed1985

Albendazole--objective evidence of response in human hydatid disease.

Thirty-two patients with cysts caused by Echinococcus granulosus were treated with albendazole in a dosage of 10 mg/kg/day. Reversible abnormalities in liver-cell function tests were seen in five patients. Some radiological evidence of remission (on serial computed tomographic or ultrasound scanning) was seen in 15 of 22 patients undergoing a therapeutic course of albendazole (as opposed to those treated before or after surgery). In five patients, the cysts virtually disappeared. Apart from reduction in size, the appearance of a halo around the cysts and the apparent disappearance of daughter cysts has been seen. Serological findings have not correlated well with radiological or clinical improvement. Serum and cyst concentrations of albendazole sulfoxide (the principal metabolite) have been measured.

Adolescent↗