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Biomedical subjects

C J Porter

Publications and source records attributed to C J Porter.

At least 109 records · Page 6Linked to original sources
PubMed1983

Verapamil: an effective calcium blocking agent for pediatric patients.

Verapamil is a slow-channel calcium-blocking agent that has been released recently by the Food and Drug Administration for treatment of cardiac dysrhythmias in all age groups. Its primary action is to slow conduction in the atrioventricular node, thereby abolishing those types of supraventricular tachycardia using the atrioventricular node as a part of the reentry circuit or slowing the ventricular rate in someone with atrial flutter. Other investigations have shown that it is likely to relieve left ventricular outflow obstruction in patients with hypertrophic obstructive cardiomyopathy. Because of its potential widespread usefulness in the pediatric population, all pediatricians should be more aware of how it is used and the potential hazards. The methods of administration and treatment of overdoses as well as indications for usage, contraindications, and adverse reactions will be explained.

Administration, Oral↗
PubMed1981

Use of guniea pigs to assay anthelmintic resistance in ovine isolates of Trichostrongylus colubriformis.

Guinea pigs infected with Trichostrongylus colubriformis were used to develop an assay for anthelmintic resistance by determination of worm burdens following treatment with test anthelmintics. To achieve comparable efficacy with the recommended dose of thiabendazole and levamisole in sheep, dose rates in guinea pigs had to be increased two to four fold. For example, thiabendazole at 100 mg/kg in guinea pigs was 96.6 per cent effective against a thiabendazole susceptible (GS) strain of T colubriformis, but had no effect against a thiabendazole-resistant (VRSG) strain. In sheep 50 mg/kg of thiabendazole would have a similar efficacy against each strain respectively. Morantel tartrate at 10 mg/kg in guinea pigs was 99 to 100 per cent effective against the GS strain but only 54 per cent effective against a morantel resistant (PF4) strain. A slope ratio assay was used to calculate the relative potency of anthelmintics by comparing efficacies against resistant strains with efficacy against the GS strain. Resistance of the VRSG strain to thiabendazole was confirmed with a relative potency for this drug of 0.047 in guinea pigs. The PF4 strain was resistant to both thiabendazole and levamisole which had relative potencies of 0.168 and 0.255 respectively. The advantages of this statistical treatment together with the cost and time savings of the guinea pig model over a conventional critical anthelmintic assay in sheep are discussed.

Animals↗
PubMed1981

Anthelmintic efficacy of low-dose phenothiazine against strains of sheep nematodes susceptible or resistant to thiabendazole, levamisole and morantel tartrate: effect on patent infections.

The anthelmintic efficacy of low-dose phenothiazine therapy, administered as a 1:40 phenothiazine: molasses mixture, was tested against patent infections of strains of Haemonchus contortus, Trichostrongylus colubriformis and Ostertagia spp susceptible or resistant to thiabendazole (an other benzimidazoles), levamisole and morantel tartrate. Phenothiazine reduced faecal egg output for both susceptible and resistant strains of all three nematodes. In daily doses of 0.25 g per sheep per day and above it completely inhibited larval production in susceptible strains. Against resistant strains, there was a reduced efficiency with 82.3 per cent inhibition of egg hatch at the 0.25 g per sheep per day level. Phenothiazine treatment had no significant effect on worm numbers for either susceptible or resistant worms. It is suggested that benzimidazole-resistant strains may be cross-resistant to phenothiazine.

Animals↗
PubMed1981

Anthelmintic efficacy of low-dose phenothiazine against strains of sheep nematodes susceptible or resistant to thiabendazole, levamisole and morantel tartrate: efficiency against sequentially administered infections.

Low-dose daily phenothiazine therapy, administered as a 1:40 phenothiazine:molasses mixture, was tested against sequential infections of strains of Haemonchus contortus. Trichostrongylus colubriformis and Ostertagia spp susceptible or resistant to thiabendazole, levamisole and morantel tartrate. Phenothiazine at a dose rate of 0.5 g per sheep per day significantly reduced the numbers of worm eggs per gram of faeces in both susceptible and resistant strains by an average of 48 per cent and 60 per cent respectively. Phenothiazine completely inhibited larval production in susceptible strains. With resistant worms, larval production was depressed by up to 85.7 per cent. Treatment with phenothiazine : molasses mixture reduced the numbers of worms which became established in resistant Ostertagia spp and susceptible T colubriformis but had no effect on the establishment of susceptible H contortus and Ostertagia spp or resistant H contortus and T colubriformis.

Administration, Oral↗
PubMed1980

Trichostrongylus colubriformis and Ostertagia sp resistant to levamisole, morantel tartrate and thiabendazole: infectivity, pathogenicity and drug efficacy in two breeds of sheep.

Merino and Border Leicester cross Merino sheep, nine months old, were infected with 10,000 third stage larvae of both Trichostrongylus colubriformis (PF4) and Ostertagia circumcincta/O trifurcata (PF5), known to have varying degrees of resistance to levamisole, morantel tartrate and thiabendazole. Crossbred sheep carried heavier Ostertagia sp worm burdens but there was no difference in susceptibility between the two breeds of sheep to infection with T colubriformis. The anthelmintic efficacy of thiabendazole, at 50 mg/kg, against T colubriformis was 81.8 per cent and 92.4 per cent for Merinos and crossbreds respectively while levamisole, at 6.75 mg/kg, was 12.3 per cent and 18 per cent effective. Thiabendazole removed 92.3 per cent and 83.8 per cent of Ostertagia sp in Merinos and crossbreds respectively. However, worm burdens in levamisole treated sheep were not significantly different from controls. No significant breed differences were found in 24 h faecal egg outputs. It is suggested that breed differences previously described in four-month-old sheep may have been due to differences in the rate of development of immune responsiveness. This disparity was no longer detectable in the immunologically mature sheep used in this study.

Animals↗
PubMed1980

Trichostrongylus colubriformis and Ostertagia sp resistant to levamisole, morantel tartrate and thiabendazole: isolation into pure strain and anthelmintic titration.

Strains of Trichostrongylus colubriformis (designated PF4) and Ostertagia sp (O circumcincta/O trifurcata, designated PF5), with varying degrees of resistance to levamisole, morantel tartrate and thiabendazole were isolated into pure culture. Detailed dose response studies showed that both T colubriformis and Ostertagia sp were highly resistant to levamisole and morantel with low level resistance to thiabendazole. The effective dose required to remove 80 per cent worm burdens (ED80) was calculated for each anthelmintic. For T colubriformis the ED80 for levamisole and thiabendazole were 12.6 and 40.1 mg/kg respectively. For Ostertagia sp, the ED80 for levamisole, thiabendazole and morantel were 20.4, 45.2 and 35.8 mg/kg respectively. The implications of these results are discussed with reference to alternative means of chemical control.

Animals↗
PubMed1978

Cardiac catheterization in the neonate. A comparison of three techniques.

This study evaluated three methods of catheter entry for cardiac catheterization in neonates less than one week of age. Eighty-five neonates underwent venous catheterization through the umbilical vein, 77 by saphenous or femoral cutdown, and 31 by femoral percutaneous entry. Of these 194 neonates, 128 also had an aortic catheter introduced via the umbilical artery. Umbilical vein catheterizations took an average of 115 minutes, 30 minutes shorter than either of the other techniques. Fatal complications following catheterization occurred in 10 of the 194 neonates (5%) three of these were related to catheterization technique. Diagnostic cardiac catheterization and balloon atrial septostomy may be performed most quickly by way of the umbilical vessels. Percutaneous entry of the femoral vein in this series carried the lowest complication rate; cutdown entry resulted in the highest complication rate.

Cardiac Catheterization↗
PubMed1978

Successful surgical correction of infradiaphragmatic total anomalous pulmonary venous return into the inferior vena cava. A fourteen-year follow-up.

This case report describes the long-term follow-up of a patient who, at 7 weeks of age, underwent surgical correction of infradiaphragmatic total anomalous pulmonary venous return (TAPVR) to the inferior vena cava. Fourteen years after operation, the patient has normal anatomy and nearly normal hemodynamics. The difference between this type of infradiaphragmatic TAPVR with posthepatic drainage is compared with the more common type which drains prehepatically.

Adolescent↗
PubMed1978

Improved technique for developing creatine kinase isoenzyme bands by using a substrate in gelatin matrix.

We describe a simple technique for reacting CK isoenzymes with a substrate in gelatin to make them visible after they have been separated by cellulose acetate electrophoresis. The electrophoresed strip requires only 5 min of contact with the substrate in gelatin and about 12 min of drying in an oven at 55 degrees C. The developed isoenzyme bands are discrete, intense, and rectangular in shape. The technique has a sensitivity of 2 to 5 U/liter, and results for isoenzyme MB can be reported about 30 min from the time a specimen is received.

Creatine Kinase↗
PubMed1976

Cholesterol in amniotic fluid, determined by gas chromatography.

Cholesterol was extracted from amniotic fluid, saponified, converted to its trimethylsilyl derivative, and gas chromatographed, with cholesteryl acetate as the internal standard. The method is sufficiently accurate and precise for use with the range of concentrations of cholesterol found in amniotic fluid (5 to 48 mg/litre). Total cholesterol was measured in amniotic fluids collected at different stages of gestation. No significant trend or change was observed nor was cholesterol in the amniotic fluid and the mother's serum correlated at any stage of gestation. Thus we conclude that cholesterol is not a useful indicator of fetal age or maturity. Cholesterol concentrations in amniotic fluid from complicated pregnancies were within the range found for normal pregnancies.

Amniotic Fluid↗