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Biomedical subjects

R G Taylor

Publications and source records attributed to R G Taylor.

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

Sarcoidosis and membranous glomerulonephritis: a significant association.

Three patients were seen who had sarcoidosis associated with glomerulonephritis. Subsequent review of published reports of cases in which the two conditions occurred simultaneously showed a pattern of histological type of glomerulonephritis different from that seen in patients without associated disease. In sarcoidosis with glomerulonephritis there appeared to be a dearth of minimal-change disease and an excess of membranous glomerulonephritis compared with the prevalence that would be expected if the renal disease was merely a chance occurrence. These findings may provide evidence for an important relation between sarcoidosis and glomerulonephritis.

Adult↗
PubMed1982

Endothelial surface characteristics in pigeon coronary artery atherosclerosis. I. Cellular alterations during the initial stages of dietary cholesterol challenge.

The early events in coronary artery atherosclerosis in White Carneau pigeons were studied by combined scanning and transmission electron microscopy. Endothelial cells throughout the right coronary artery were elongate in shape, having an axial ratio (width + length) of 0.48 +/- 0.03, and were oriented with the long axis parallel to the direction of blood flow. Deviation in both orientation and morphology were found in control birds in zones of high probability for disease. Endothelial cells in the high predilection zones were less elongate in shape, having an axial ratio of 0.69 +/- 0.04, and had poorly defined margins and a paucity of microvilli. These less elongate cells were on the average 50 per cent larger (surface area of 147.9 +/- 13.3 versus 93.4 +/- 5.5 sq. microns for the typical cell) than the normal endothelial cell. Upon cholesterol challenge, the percentage of elongate cells decreased in the high propensity zones within the first few weeks, and following 8 weeks of cholesterol challenge the less elongate cells were associated with nascent atherosclerotic lesions. In addition to these large irregularly shaped endothelial cells, the early lesions characteristically were encircled by small cells having prominant nuclei and a large number of microvilli clustered over the nuclear area. Continuation of the cholesterol diet beyond 36 weeks resulted in progressive lesion enlargement and the selective binding of blood cells to the lesion periphery. This margination of blood cells was maximal at 36 weeks when the process was evident in 60 per cent of the cholesterol-fed animals. With further prolongation of cholesterol challenge, adherent cells were found in only 25 per cent of the birds. The surface events observed by scanning electron microscopy were correlated with ultrastructural changes in the endothelial glycocalyx. Cholesterol challenge resulted in a significant reduction in both the amount of ruthenium red stain and the number of cationized ferritin particles which were bound to luminal surfaces. In control diet animals, the glycocalyx thickness was in the range of 700 to 1000 A, with the thinnest areas being those in zones of high disease predilection and numerous nonelongate endothelial cells. When analyzed on an individual cell basis, the villus portions of the endothelial surface (glycocalyx thickness, 436 A) averaged 64 per cent thinner than the nonvillus portions of the cell. Upon cholesterol challenge, the glycocalyx was reduced in all arterial zones to 450 A, which approximated the thickness found for microvilli. Our results clearly document changes in endothelial morphology during the early stages of coronary atherosclerosis. These morphologic features are discussed with respect to the role the altered cells may play in disease progression.

Animals↗
PubMed1982

Surface characteristics of adherent avian cells; extrapolation of in vitro characteristics to cells on atherosclerotic lesions.

Through the use of correlative Wright's stain and scanning electron microscopy (SEM), the distinguishing surface characteristics of adherent pigeon blood cells have been determined. The identification criteria, established by using an in vitro adhesion system, have been extrapolated to cells associated with the surface of atherosclerotic lesions. The results presented in this paper clearly distinguish erythrocytes, thrombocytes and lymphocytes from monocytes and granulocytes. Erythrocytes are fusiform in shape and have a distinctively smooth plasma membrane. Thrombocytes, smaller than erythrocytes but also fusiform, extend numerous filipodia when surface activated. Often a delicate hyalomere connects adjacent filipodia on the substrate. In contrast to erythrocytes and thrombocytes, lymphocytes are round cells whose plasma membrane forms numerous stubby microvilli. Monocytes and granulocytes can be distinguished from the other cell types by their larger size; however, the distinction between the two is much finer than the previous three blood cell lines. When adherent, both retain a round, nuclear region often encircled by a hyalomere apposing the substrate; the discrete difference between granulocytes and monocytes lies in the convolutions of the plasma membrane. The monocyte membrane folds into ruffles covering both the nuclear area and hyalomere; whereas, the granulocyte membrane forms small microvilli and cytoplasmic ridges only over the nuclear area. The SEM descriptions of adherent pigeon blood cells were demonstrated to be potentially useful in identifying cells adherent to early atherosclerotic lesions in pigeon coronary arteries.

Animals↗
PubMed1981

Microfilament reorganization in normal and cytochalasin B treated adherent thrombocytes.

Thrombocyte adhesion following activation by a Formvar surface involves a morphologic transition resulting in a fully spread cell. Correlative SEM and whole mount TEM were used to study the cytoskeletal alterations that accompany changes in surface morphology during adhesion. Following initial adhesion, thrombocytes extend slender pseudopods containing longitudinally oriented bundles of filaments that are 13-22 nm in diameter. Concomitant with pseudopod extension, a cytoplasmic hyalomere, consisting of a dense filamentous network, extends between the pseudopods and ultimately results in a fully spread cell. Treatment of thrombocytes with cytochalasin B (10(-5) M) caused clumping of the hyalomere filament network and retraction of the hyalomere. Examination of partially retracted cells revealed that pseudopod filament bundles were continuous with the contracting filamentous network. It is concluded that pseudopod filament bundles and cytoplasmic hyalomere filaments are interconvertible and that their organizational relationship changes in accordance with gross morphologic changes.

Blood Platelets↗
PubMed1981

Plasma sex hormone concentrations in men with hypertension treated with methyldopa and/or propranolol.

Serum concentrations of LH, FSH, testosterone and prolactin were measured in patients with hypertension treated with propranolol (34 cases), methyldopa (13 cases), and methyldopa + propranolol (11 cases). The results were compared with those obtained in 18 controls (hospital out-patients). There were no differences in these hormone concentrations in the various groups, and no difference between those complaining of impotence (13 cases) and those with normal sexual function. Impotence in hypertensive men on treatment with methyldopa cannot be explained by abnormalities in secretion of the reproductive hormones.

Adult↗
PubMed1981

Pantalar arthrodesis: a long-term follow-up.

Eighty-three pantalar arthrodeses in 69 patients performed at the Shriners Hospital for Crippled Children, Greenville, South Carolina, between 1941 and 1977 were evaluated. Follow-up was from 1 to 33 years. Diagnoses included poliomyelitis, myelodysplasia, arthrogryposis, clubfeet, and extremity or spinal cord trauma. Methods of fusion were one-stage pantalar arthrodesis, two-stage triple ankle fusion, one-stage completion of prior tarsal fusion, and one-stage denudation of the talus. Pantalar arthrodesis is successful in the paralytic sensitive foot with a stable knee and there is no greater incidence of nonunion in the one-stage (Hunt-Thompson) procedure than in the two-stage procedure. Complications and failure of fusion are common in the insensitive foot.

Ankle Joint↗
PubMed1980

Perinatal neuropathy as an early manifestation of Krabbe's disease.

An asymptomatic child with antenatally diagnosed globoid cell leukodystrophy was found to have electrodiagnostic evidence of peripheral neuropathy at 7 weeks of age. The earliest prior such evidence in the literature was in a 6-month-old-child. Thus, peripheral neuropathy can be both the initial manifestation and a very early finding in Krabbe's disease.

Electrodiagnosis↗
PubMed1980

Stretch-induced growth in chicken wing muscles: a new model of stretch hypertrophy.

A new model of stretch-induced growth is evaluated in four chicken wing muscles stretched to different extents by a spring-loaded tubular assembly. Muscles grew in length and cross section in proportion to the extent to which they were stretched. Longitudinal growth was essentially completed within 1 wk, while muscles grew in cross section through at least 5 wk of stretch. The muscles were neither denervated nor immobilized, and muscle activity as measured by EMG was not increased. Oxidative enzyme activities increased substantially with stretch in the patagialis (PAT), a twitch muscle, but were relatively unchanged in the slow-tonic anterior latissimus dorsi (ALD). Stretch altered mitochondrial enzyme proportions in the PAT, but had little effect in the ALD. Capillary density was unchanged with stretch in the PAT, but decreased in the ALD. Capillary density was unchanged with stretch in the PAT, but decreased in the ALD. Capillary-to-fiber ratio, however, increased in both muscles. We conclude that muscles grow and adapt enzymatically due to stretch, but that these responses are dissimilar in twitch and tonic muscles.

Action Potentials↗
PubMed1980

The use of correlative SEM and TEM to study thrombocyte and platelet adhesion to artificial surfaces.

Platelet adhesion is a complex process involving circulating cells, the damaged vessel wall and the complex medium of plasma in which the events take place. Elucidation of several cellular changes which occur during adhesion has been enhanced through the use of conventional transmission and scanning electron microscopy; however, many question, particularly relating to cytoplasmic control of cellular reorganization have remained unanswered. This paper describes the preparative techniques and the potential for use of correlative stereo SEM and TEM in studies of platelet adhesion. Three particular techniques: (1) stereo SEM, (2) stereo SEM-TEM of digest replicas and (3) whole mount stereo TEM are described. The applicability of these techniques to areas of cytoplasmic filaments organization, granule movement, and cell to cell contact organization is suggested.

Animals↗
PubMed1980

Fast and slow skeletal muscles: contractility evaluated by paired stimuli in mice.

The purpose of this study was to evaluate a technique for in vitro study of mouse skeletal muscle, to determine if paired stimuli would allow estimation of new time parameters of contraction. Conventional tension measurements were obtained, plus the time measurements from the paired stimulus studies. The muscles were also subjected to fatigue by repetitive tetanization. A fast muscle (extensor digitorum longus or plantaris) and a slow muscle (soleus) were studied in each preparation. Studies were conducted at physiologic (35C) and at nonphysiologic (20C) temperatures. Data obtained indicate that this isometric in vitro method allows subdivision of results into 3 categories of effect due to treatment related to the functional muscle compartments: 1) chronotropic-excitation contraction coupling mechanisms, 2) inotropic- contractile elements, and 3) metabolic (fatigue)-energy supply mechanisms. When results as 20C were compared with physiologic temperature, a negative chronotropic effect was observed for all parameters in all 3 muscles. A positive inotropic effect was observed for twitch with no change or a negative effect for all other tension parameters. The lower temperature produced slight protection from fatigue. Models were developed to demonstrate how data from isometric studies fit the original concepts developed using isotonic methods. The model and method should prove of value in detecting the acute effect of drugs or of other therapy imposed on skeletal muscles.

Animals↗
PubMed1980

Fast and slow skeletal muscles: effect of secobarbital on contractility of muscles from mice.

In vitro studies were performed on fast and slow muscles from mice to determine if secobarbital sodium (SCB) has a direct effect on muscle contractility. All preparations were curarized and stimulation was direct. After baseline studies, SCB was added to the muscle bath in 1 of 4 concentrations-10, 20, 100 and 200 microgram/ml. Tetanic tension was reduced for both muscle types at SCB concentrations greater than or equal to 20 microgram/ml, and loss was progressive with increasing dose. In contrast, twitch tension (P) was increased by SCB at the 2 higher concentrations. The increase in P was due to an increase in rate of tension development plus prolongation of the time parameter (duration) of the twitch. Fatigue was accelerated by SCB for both muscle types. The results indicate that SCB has a direct and similar effect on fast and slow skeletal muscles. The probable sites of action of the drug are the excitation contraction coupling mechanisms and the mechanisms for energy production and/or utilization.

Animals↗
PubMed1980

Serial phrenic nerve conduction studies in candidates for diaphragm pacing.

Serial phrenic nerve conduction studies in 3 patients with high cervical cord injuries have demonstrated a pattern of function that changes with time. Nerves may be responsive initially and may then become unresponsive only to have responses reappear at a later date. Before a final decision is made about phrenic nerve viability prior to diaphragm pacing, serial studies should be carried out for at least 6 weeks postinjury on initially responsive nerves, and for at least 2 years postinjury on nonresponsive nerves or those with a changing functional pattern.

Adult↗
PubMed1980

Intraarterial secobarbital: muscle injury evaluated by electrodiagnosis in four cases.

A syndrome of severe upper extremity pain, swelling and weakness following intraarterial injection of illicit secobarbital was evaluated in 4 patients. Although the involved muscle mass was small, serum muscle enzymes were markedly elevated. Electromyography (emg) revealed fibrillation and positive sharp wave potentials at 7 days. Motor unit action potentials were of low amplitude and of brief duration but markedly reduced in numbers, a mixture of myopathic and neuropathic changes. Motor nerve conduction velocities and latencies were normal, but M-wave amplitudes were small. Serial studies in 1 patient revealed persistent fibrillation and positive sharp waves in all involved muscles with absent voluntary contraction in the ulnar muscles and no response to stimulation of the ulnar nerve at 60 days postinjection. The emg and conduction studies for the median nerve distribution were normal except for the abnormal rest activity. A muscle biopsy (on day 66) in this patient revealed findings compatible with neuropathy, myopathy and vasculitis. The results indicate that electrodiagnostic studies may be of value for prognosis in these cases by evaluating the extent of neuromyopathic involvement.

Adolescent↗