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Biomedical subjects

R D Harris

Publications and source records attributed to R D Harris.

At least 109 records · Page 6Linked to original sources
PubMed1982

Irradiation crosslinking of the polytetrapeptide of elastin and compounding to dacron to produce a potential prosthetic material with elasticity and strength.

The poly(tetra peptide), H-(L . Val1-L . Pro2-Gly3-Gly4)n-L . Val-OMe, which is a recurring sequence in tropoelastin the precursor protein of the elastic fiber, has been irradiation crosslinked to produce an elastomeric material with limited strength. When a material such as a Dacron fabric is impregnated by the coacervate phase of the poly(tetrapeptide) prior to irradiation crosslinking at 50 Mrad, the crosslinked product exhibits stress-strain curves with good elastomeric properties and high strength. In addition to the stress-strain curves, the material is characterized by scanning electron microscopy.

Biocompatible Materials↗
PubMed1981

Computed tomographic diagnosis of renal infarction.

Two cases of renal infarcts diagnosed on CT scans are presented which demonstrate findings that should be identifiable and diagnostic to indicate renal infarction. The examination is more reliable and specific if it is performed after the administration of intravenous radiographic contrast material. The contrast can be given either by a bolus or an infusion injection. The findings after contrast-enhanced scan should be specific enough to identify the cause of the patient's symptoms. A percutaneous CT guided biopsy can be performed to confirm the diagnosis.

Adult↗
PubMed1981

The child-adolescent blood pressure study: I. Distribution of blood pressure levels in Seventh-Day-Adventist (SDA) and non-SDA children.

Distribution of systolic and diastolic blood pressures (measured with an automated blood pressure recorder) of two large groups of children-3,159 from Seventh-Day Adventist (SDA) schools and 4,681 from non-SDA schools-are reported. They boys and girls were from four different ethnic groups and attended grades one through 10 in 29 Southern California schools. The analysis of the data failed to show significant differences in mean blood pressure levels between the two groups of children at all ages, despite marked differences in life-style between the two groups, and despite the fact that adults from the two population groups have marked differences in mortality from diseases associated with elevated blood pressure. A comparison between boys and girls showed significantly higher trends in mean systolic blood pressure for boys after age 12. Inter-ethnic comparisons of blood pressure revealed that Black children of both sexes had slightly higher mean blood pressure levels at all ages.

Adolescent↗
PubMed1981

Compounding of elastin polypentapeptide to collagen analogue: a potential elastomeric prosthetic material.

The polypentapeptide, H-(L . Val1-L . Pro2-Gly3-L . Val4-Gly5)n-L . Val-OMe, which is the most common recurring sequence within the elastic fiber, is demonstrated to be elastomeric when irradiation cross-linked but to have limited strength. On irradiation compounding with a collagen analogue, such as Dacron, stress-strain studies show the product to have an elastic modulus greater than that of fibrous aortic elastin and similar to that of aortic wall. In addition, the compounded product has the requisite strength. Of the 40, 50 and 60 MRAD cross-linked polypentapeptide-Dacron products, those derived from the larger doses of 50 and 60 MRAD exhibited somewhat better elastomeric properties. The unstretched and stretched products were characterized by scanning electron microscopy which demonstrated the importance of a fabric weave with a uniform extension. In general irradiation cross-linking has the advantage of being able to produce larger quantities of elastomeric material and compounding to a collagen analogue provides the required strength.

Collagen↗
PubMed1980

Clinical laboratory: enzyme immunoassay for the rapid clinical identification of snake venom.

The treatment of snakebite could be simplified if the identity of the offending snake was more frequently known. A positive identification, which allows the use of a specific monovalent antivenom, probably occurs in less than 20% of cases. Recently published methods of venom detection (RIA and ELISA) take at least three hours to complete. We have developed a sandwich enzyme immunoassay (EIA) which is capable of detecting 0.5 ng of crude snake venom in about 90 minutes or 2 ng of crude venom in about 30 minutes. This substantial reduction in incubation times, while still retaining the sensitivity required, was due to the use of protein A purified rabbit IgG antivenom from hyperimmune serum and the enzyme horseradish peroxidase (HRPO). A rapid identification of the offending snake by this method may reduce the use of large-volume polyvent antivenoms, thus avoiding the clinical and economic disadvantages of such preparations. Other advantages would be an increased understanding of the clinical syndrome produced by the individual species of snake, and accumulation of data about the incidence of envenoming attributed to specific snakes.

Animals↗
PubMed1980

Combined embolization and operation in the treatment of cervical arteriovenous malformations.

The effectiveness of a combined approach of embolization and operation for cervical vascular malformations is stressed. Lesions that seem to be inoperable may have their blood flow sufficiently reduced by preoperative embolization to allow surgical extirpation. Polyvinyl alcohol foam is an ideal embolic agent; not only may it be used preoperatively, but its permanency allows it to be used for primary therapy.

Adolescent↗
PubMed1979

Rationalisation of first-aid measures for elapid snakebite.

The plasma of monkeys envenomated with tiger snake (Notechis scutatus) venom was monitored by radioimmunoassay for both crude venom and a neurotoxin. When the injected limb was immobilised and a pressure of 55 mm Hg applied to the injection site, only very low levels of circulating venom or neurotoxin were detectable. In practical terms, venom movement can be effectively delayed for long periods by the application of a firm crepe bandage to the length of the bitten limb combined with immobilisation by a splint. Pressure alone or immobilisation alone did not delay venom movement.

Animals↗
PubMed1979

Computed tomographic evaluation of pear-shaped bladder.

Computed tomography (CT) was used to distinguish between pelvic lipomatosis and idiopathic inferior vena caval thrombosis as a cause of a pear-shaped bladder seen on intravenous urography. The findings on CT were explicit in explaining the patient's clinical problem.

Adult↗
PubMed1979

Computerized tomography of retroperitoneal lymphadenopathy: benign or malignant.

A distinguishing feature has been noted to help differentiate between malignant retroperitoneal nodes and nodes which contain reactive hyperplasia. This sign is the presence of a cleavage plane between the mass of nodes and the great vessels which are easily visible in benign disease. This distinction is in reference to malignant nodal disease where the contours of the vessels are obscured. The ability to make a diagnosis of benign disease on CAT scan has enabled us to choose the appropriate course of therapy and, in some patients, allowed us to avoid exploratory laparotomy for diagnosis.

Adenocarcinoma↗
PubMed1979

Computerized tomographic diagnosis of aneurysms of the thoracic aorta.

Accurate diagnosis of aneurysms of the thoracic aorta and its major branches can easily be performed by CT scanning of the mediastinum. The use of contrast enhancement aids in the diagnosis and allows distinction between flowing and clotted blood within the aneurysm. CT scanning of these lesions seen on chest radiographs may obviate the need for arteriography for diagnosis.

Aged↗