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Biomedical subjects

R Jones

Publications and source records attributed to R Jones.

At least 811 records · Page 45Linked to original sources
PubMed1986

Preparation of a plasma membrane-rich fraction from rat spermatozoa.

Monoclonal antibodies to antigens located on surface and intracellular membranes of spermatozoa from the rat cauda epididymidis have been used as probes to assess the purity of putative plasma membrane fractions. Spermatozoa were demembranated by shearing forces generated on a vortex-mixer. Immunofluorescence and ultrastructural analysis of vortex-mixed spermatozoa showed that they were denuded of approximately 90% of surface membrane. Areas of acrosomal membranes were also removed. Crude plasma membranes were recovered in low-speed wash fluids and fractionated on a 13-23% Nycodenz density gradient. Three bands containing membrane vesicles were resolved. Absorption curves and direct binding assays using monoclonal antibodies specific for acrosomal membranes, mitochondrial membranes and fibrous sheath showed relatively strong binding to bands 1 and 2 but weak binding to band 3. Conversely a monoclonal antibody specific for a surface membrane antigen bound strongly to band 3 and weakly to bands 1 and 2. Identification on immunoblots of the antigens recognized by the monoclonal antibodies revealed that band 3 was positive for surface membrane antigens but gave no reaction for intracellular antigens. However, bands 1 and 2 were strongly positive for intracellular components. The results suggest that vortex-mixing is a simple and efficient means of removing the plasma membrane from spermatozoa and that a membrane fraction can be recovered from a Nycodenz density gradient that is enriched 40- to 50-fold in surface antigens.

Animals↗
PubMed1986

Correlation between the number of placental opioid receptors, mode of delivery, and maternal narcotic use.

Human placental opioid receptors were assayed using the radioactive opioid agonist, etorphine, to determine the number of binding sites in villous tissue membrane preparations. Significant differences in receptor concentration per milligram of protein of tissue were found between placentas obtained following vaginal or abdominal delivery (P less than 0.002). Labor itself did not alter apparent receptor numbers. In patients with maternal narcotic abuse during pregnancy, no opioid binding could be detected regardless of the mode of delivery, suggesting possible receptor down-regulation.

Cesarean Section↗
PubMed1986

Lateral asymmetries in finger-tapping by adolescents and young adults with Down syndrome.

Lateral asymmetries in finger-tapping were compared in right-handed adolescents and young adults with and without Down syndrome in order to examine cerebral specialization in the Down syndrome group. Finger-tapping data revealed that subjects with Down syndrome performed more slowly than did control subjects and failed to show a right-hand tapping advantage. Although the latter finding suggests that individuals with Down syndrome are less lateralized for sequential processing, they exhibited the same pattern of tapping variability as did control subjects; i.e., they were more variable when finger-tapping with their left hands.

Adolescent↗
PubMed1986

Rat pulmonary artery wall injury by chronic intermittent infusions of Escherichia coli endotoxin. Obliterative vasculitis and vascular occlusion.

To examine the effect of intermittent endotoxemia on rat pulmonary artery structure and hemodynamic function we infused purified Escherichia coli endotoxin on four occasions over 3 weeks (at 7-day intervals), through an indwelling catheter placed in the external jugular vein. The fourth infusion of endotoxin was associated with widespread but focal alveolar consolidation, reduced perfusion of small pulmonary arteries by lumen occlusion and obliteration, pulmonary vascular wall injury, and a peripheral leukocytosis (mean +/- SEM total leukocytes, endotoxin 133.5 +/- 23 X 10 mm3, control 12.2 +/- 1.2 X 10 mm3, p less than 0.001) in which polymorphonuclear (PMN) leukocytes predominated at the expense of lymphocytes (p2x less than 0.01). The alveolar wall was thickened and the alveolar space was consolidated by degenerating polymorphonuclear leukocytes, mononuclear cells, lipid laden alveolar macrophages, erythrocytes, fibrin, and cell debris. In regions of alveolar consolidation vessel lumens were either narrowed by subendothelial cell collections that consisted either of mononuclear cells or degenerating mural and inflammatory cells, or they were occluded by degenerating inflammatory cells and cell debris. The walls of occluded vessels were evident only by their residual elastic laminae: remnants of lysed endothelial cells lined the intima and the media consisted of degenerating mural and inflammatory cells. Capillary endothelial cells showed extensive hydropic degeneration and lysis of cell contents. Intimal precursor smooth muscle cells were hypertrophied but were not associated with the appearance of mature smooth muscle cells in the walls of small pulmonary arteries. In regions of less severe alveolar consolidation by inflammatory cells, vessel wall injury was still evident but less marked; precursor smooth muscle cells were hypertrophied; subepithelial and subendothelial collections of fluid and fibrin were present; and plasma membranes of endothelial cells were disrupted. Despite extensive pulmonary vascular injury, chronic intermittent endotoxemia did not produce the structural changes associated with pulmonary hypertension (medial thickening and appearance of medial muscle in previously nonmuscular arteries) nor a significant change in pulmonary artery pressure.

Animals↗
PubMed1986

Upper gastrointestinal endoscopy--a view from general practice.

An open-access upper gastrointestinal endoscopy service for general practitioners is described. Between July 1981 and May 1985, 391 endoscopies were performed on 354 patients. In contrast to the results of other studies, demand for endoscopy and the pick-up rate for major lesions has remained steady, and the number of requests for barium meals has fallen by almost a quarter. Major lesions - cancer, gastric and duodenal ulcers and severe oesophagitis - were found in 33% of patients. Oesophagitis accounted for 28% of positive endoscopies and 18% of positive endoscopies in patients with barium negative dyspepsia. With scarce resources there may, however, be a case for ;selective' access to upper gastrointestinal endoscopy in the future.

Adult↗
PubMed1986

Three-day and seven-day treatment in acute otitis media: a double-blind antibiotic trial.

Ninety-six children with acute otitis media were randomized into a double-blind general practice trial of three-day and seven-day courses of cefaclor 125 mg tds. These regimens were equally effective in terms of resolution of symptoms and signs of otitis media, even in children presenting with bulging of the tympanic membrane. There was no difference between the groups in the recurrence of middle-ear infection during the six weeks after entry to the trial. The results provide further evidence about the effectiveness of short courses of antibiotics for children with presumed middle-ear infection.

Acute Disease↗
PubMed1986

Jones-Hedman walker modification for C7 quadriplegic patient: case study in team cooperation.

A 20-year-old man with C7 quadriplegia was admitted to a tertiary care rehabilitation facility 1.5 months after discharge from an acute care community hospital. The patient's goals were to improve his skills in activities of daily living to a level of maximum independence, and to walk. Although his high level of spinal cord injury made ambulation unlikely, an occupational therapist and a rehabilitation engineer, working together, devised a method to help the patient meet his ambulation goal. They modified an ordinary walker by fabricating polyvinyl chloride-acrylic alloy guards lined with foam to reduce palmar pressure. The patient was then able to use wrist and finger extension during walker advancement and was able to ambulate 300m with Craig-Scott orthosis. The case illustrates the importance of a skilled interdisciplinary team in a specialized center for management of spinal cord injured patients.

Adult↗
PubMed1986

Rod and cone ERGs and their oscillatory potentials.

Normal human ERGs were recorded from a dark-adapted subject using white and colored test flashes. Oscillatory potentials (OPs) were studied after high-pass digital filtering. When blue and red responses were compared at equivalent photopic intensities, OPs were visible at much lower intensities for the blue flashes. As the intensity was reduced from maximum, the first (negative) wave for red flashes maintained a latency of 20-25 msec before being lost in noise, whereas the first wave for blue flashes increased its latency progressively from 25 to 60 msec. These differences between photopically matched red and blue responses are interpreted to be due to rod-generated responses. When blue, orange, and white responses were compared at equivalent scotopic intensities, the latency of the largest negative wave was found to be similar for all three colors. The authors interpret this wave to be the beginning of the rod-generated OPs, so that the preceding waves (particularly evident for orange flashes) are cone-generated OPs, and they propose that the existence of separate rod and cone OPs should be borne in mind when investigating clinical changes in OPs.

Action Potentials↗
PubMed1985

Monomeric Acanthamoeba myosins I support movement in vitro.

Acanthamoeba myosins IA and IB were found to have molecular weights of 159,000 and 150,000 and Stokes radii of 6.2 and 5.9 nm, respectively. Both enzymes have frictional ratios of 1.7. Myosin IA consists of 22% alpha-helix, 32% beta-structure, and 46% unordered structure, while myosin IB is 16% alpha-helix, 46% beta-structure, and 38% unordered. Both myosins remain monomolecular under conditions in which other myosins form filaments. Beads coated with myosin IA or IB move unidirectionally on actin cables of Nitella. Movement requires ATP and phosphorylation of the myosin I heavy chain which is also required for actin-activated Mg2+-ATPase activity. Movement is inhibited by myosin I antiserum that inhibits actin-activated ATPase activity. These studies establish that these nonfilamentous, monomolecular myosins with single heavy chains of 130,000 and 125,000 daltons (IA and IB, respectively) can support actin-dependent movement analogous to that supported by filamentous myosins.

Adenosine Triphosphatases↗