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Biomedical subjects

J R Pemberton

Publications and source records attributed to J R Pemberton.

18 recordsLinked to original sources
PubMed1988

A review of surgery for acquired tricuspid valve disease, including an assessment of the stented semilunar homograft valve, and the results of operation for multivalvular heart disease.

A total of 246 operations were performed in 230 patients for correction of acquired tricuspid valve disease. All but three of the patients had multivalvular heart disease. There was an 11% hospital mortality which fell to 7% in the later era (1973-82). Mortality was similar for tricuspid annuloplasty and tricuspid replacement and for double and triple valve surgery. On multivariate analysis the incremental risk factors for hospital death were extreme functional disability (Class V), being of Caucasian race, and having a high cardiothoracic ratio (CTR). Actuarial survival was 58% at 9 years postoperative. The incremental risk factors for late death were prior cardiac surgery, age at operation greater than or equal to 55 years, and advanced functional disability (Classes IV, V). The actuarial incidence of significant tricuspid incompetence following annuloplasty was 12% at 3 years, and following stented homograft semilunar valve replacement was 6% at 3 years and 24% at 8 years. Severe homograft valve incompetence was always associated with recurrent left-sided valve lesions or residual pulmonary hypertension. It is concluded that a homograft valve is a superior form of tricuspid valve replacement.

Adolescent↗
PubMed1987

Long-term follow-up of patients with the antibiotic-sterilized aortic homograft valve inserted freehand in the aortic position.

A series of 252 isolated aortic homograft valves in 248 patients have been followed for 9 to 16.5 years (mean 10.8). The valves were sterilized in antibiotic solution and stored in a nutrient medium at 4 degrees C and were nonvital. There were 15 in-hospital deaths (6%) and a mortality of 2.7% in patients undergoing an elective first operation. Actuarial survival with the study valve in situ was 57% at 10 years and 38% at 14 years. Only 8.4% of the patients died late from homograft valve failure, chiefly because of failure to refer patients with endocarditis for reoperation or because reoperation was refused in elderly, frail subjects. Incompetence was the sole cause of valve failure and was due either to valve wear or endocarditis. Significant incompetence required reoperation. On actuarial analysis, freedom from significant incompetence for the entire group was 95% at 5 years, 78% at 10 years, and 42% at 14 years. Factors increasing the risk of significant incompetence due to valve wear on multivariate analysis were increasing donor valve age (greater than or equal to 55 years), recipient age (less than 15 years), and an aortic root diameter over 30 mm. Analysis of the patient group that excluded each of these variables (low-risk group), which comprised 61% of the study population, indicated freedom from significant incompetence due to valve wear of 98% at 5 years, 94% at 9 years, and 56% at 13 years.

Actuarial Analysis↗
PubMed1976

Critical factors of the vacuum-oven technique which influence the estimation of moisture in veterinary biologics.

When striving toward standardization of lyophilized products, it is often difficult to correlate biological characteristics and residual-moisture content because of the great variety of assay procedures being used to estimate residual moisture. Even when moisture assays are performed according to the same general assay procedure, there are often subtle differences that cause large variations in results. Critical factors of the vacuum-oven technique such as: homogeneity and number of samples, size of samples, moisture adsorption of dry weighing dishes, efficacy of disiccator jars, influence of ambient conditions, controlling time-sequence of the test, tolerances of the test, etc. are discussed and data presented to demonstrate how some of these factors can strongly influence the results of the assay. The validity of the assay and the subsequent judgement about the quality of the final product are greatly dependent upon how well these factors are controlled.

Adenoviruses, Canine↗
PubMed1975

Physical-chemical properties of precipitated and fractionated allergens from Mycobacterium bovis.

Seven allergens were prepared from cultures of Mycobacterium bovis. The culture filtrates were divided in half and each aliquot precipitated with either ammonium sulfate or trichloroacetic acid to prepare purified protein derivatives (PPD). These samples of PPD-bovis were analyzed for nitrogen, carbohydrate, RNA and DNA. Physical tests, such as: cellulose acetate electrophoresis, disc gel electrophoresis, ultracentrifugation, isoelectricfocusing and gel filtration were also performed. Precipitation with ammonium sulfate provided PPD's with less impurities than those precipitated with trichloroacetic acid although there was little difference in the allergenic activity of the products precipitated by either method. Several lots of PPD-bovis were fractionated by means of ultrafiltration and the fractions analyzed by many of the above chemical and physical tests as well as tests for amino acid composition and allergenic activity. The greatest amount of protein was found in the fractions with an apparent molecular weight in excess of 300,000. The carbohydrate was usually distributed in proportion to the amount of protein in each fraction while the nucleic acids were predominately found in the higher molecular weight fractions. The amino acid analysis and allergenic activity of the various molecular weight fractions provided data that would support the theory that the various fractions are polymers of a small molecular weight sub-unit. The number of amino acid residues were calculated and the minimum molecular weight of the tubercular protein estimated to be 8700. The estimated molecular weights of the fractions and the amino acid data concur with those previously reported for proteins from other mycobacteria.

Allergens↗
PubMed1974

Analysis of mercurial preservatives in bacterins, vaccines, and antisera by atomic absorption spectrophotometry.

A flameless atomic absorption method was developed for the determination of mercurial preservatives in biologicals. The assay was based on a quantitative determination of the mercury content of these preservatives. This method was used to analyze a variety of samples and yielded reproducible results with satisfactory recoveries. The procedure is presented in a simplified block diagram and described in detail relating its suitability for routine assay of large numbers of samples.

Bacteriocins↗
PubMed1971

Simultaneous use of contrasting fluorochromes to separate measles and canine distemper viruses in a common system.

Measles and canine distemper viruses were grown together in a Vero monkey kidney cell line. Each virus could be identified and individually titrated by using the color contrast produced by the reddish tetra-methyl rhodamine isothiocyanate-tagged antimeasles conjugate and the green fluorescein isothiocyanate-tagged antidistemper conjugate. Both blue light and green light were used for the excitation of the fluorochromes. Incident light was transmitted to the specimen by a vertical illuminator of the Ploem type.

Animals↗