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Biomedical subjects

J Dixon

Publications and source records attributed to J Dixon.

At least 181 records · Page 10Linked to original sources
PubMed1982

Low-frequency voltage noise in a mammalian bone cell clone.

Measurements were made of plasma membrane voltage noise in cells of a bone cell clone. The measurements were made under conditions intended to approximate in vivo conditions more closely than in previous electrical measurements on small mammalian cells. Mononucleate cells of normal size, imbedded in a collagen matrix, were used. The electrical state of the cell membrane under normal conditions was characterized by low-frequency random fluctuations (noise) of high magnitude. Hyperpolarizing spikes were observed in some cells. Power spectrum analysis revealed that the random fluctuations were actually a sum of incoherent spike patterns, with spikes of the same time width as those seen in the clearly spiking patterns. This analysis, combined with similar measurements in a high [K+], low [Na+] medium, showed that the fluctuation/spiking phenomenon resulted from modulation of K+ and Na+ transport by a control process at a level higher than that of the individual channels. This process persisted when the membrane potential was depolarized. These results indicate that the membrane potential is not part of the feedback loop producing the fluctuation/spiking phenomenon.

Animals↗
PubMed1982

Preparation of hepatitis B polypeptide micelles from human carrier plasma.

Water-soluble protein micelles consisting of the 28,000 (gp28) and 23,00 (p23) molecular weight polypeptide complex of hepatitis B surface antigen can be readily prepared from human plasma containing the surface antigen and other markers of infection with hepatitis B virus. The antigenic activity of the polypeptides was preserved throughout the process of solubilisation and reassociation into micelles. Such preparations are therefore eminently suitable as "second generation" hepatitis B vaccines.

Carrier State↗
PubMed1981

Management of fissure fractures in Paget's disease.

Forty-five patients with Paget's disease were studied, of whom 25 had fissure fractures affecting the bones of the lower limb. Ten patients treated with salmon calcitonin showed no improvement in their fissure fractures despite reduction in bone turnover. Treatment was effective where bone deformity was improved by traction or intra-medullary nail fixation combined with osteotomy. Surgical treatment should be undertaken in those patients who complain of acute pain at the site of a fissure fracture and who risk completing the fracture. Fissure fractures involving the femoral neck should be fixed even when asymptomatic because of the risk of non-union if they become complete.

Aged↗
PubMed1981

Effects of amphotericin B on hepatitis B virus.

We investigated the effects of amphotericin B (AmB) on the ultrastructure and biochemistry of hepatitis B virus (HBV) and hepatitis B surface antigen (HBsAg) particles. These effects were compared with those reported for AmB and other polyene antibiotics on other lipid-enveloped viruses and artificial membranes. Treatment of HBV particles with concentrations of AmB ranging from 5 to 250 microgram/ml resulted in (i) an increase in HBV deoxyribonucleic acid polymerase activity as the concentration of Amb increased; (ii) changes in the electron microscopic appearance of HBV ranging from increased penetration of negative stain into the lipid envelope to disruption of the virus; and (iii) an increase in density form 1.165 to 1.225 g/ml. In addition, AmB treatment of HBsAg particles resulted in disruption into a nonparticulate HBsAg-reactive fraction and an HBsAg-AmB complex fraction with no HBsAg immunoreactivity.

Amphotericin B↗
PubMed1981

Progressive renal failure in surgically treated hyperparathyroidism.

Of 570 patients operated on for hyperparathyroidism, 18 subsequently died (between one day and 12 yr after operation). Pathological findings at necropsy in these patients have been reviewed. Four necropsies on patients with untreated hyperparathyroidism have also been reviewed for comparison. Of these 22 cases, 14 had renal failure at the time of death. This was attributed to the following: nephrocalcinosis 6; chronic glomerulonephritis 4; analgesic nephropathy 1; cystinuria 1; sarcoidosis 1; and polycystic disease 1. Of those with renal failure due to nephrocalcinosis, three had persistent hypercalcaemia after operation; the other three survived only for a short time. There was no evidence of residual nephrocalcinosis producing progressive renal failure if the plasma calcium concentration was corrected. In those with chronic glomerulonephritis, cystinuria, and polycystic disease, the hyperparathyroidism was considered to be tertiary to the renal disease but renal failure was not always present at the time of diagnosis.

Adult↗
PubMed1980

Experimental subglottic stenosis: histopathologic and bronchoscopic comparison of electrosurgical, cryosurgical, and laser resection.

Controversy continues over the optimal method of resecting subglottic stenosis. Electrosurgery, cryosurgery and laser resection have all had some clinical success. We sought to compare these treatment methods in experimentally-created subglottic stenosis. Subglottic strictures were created transbronchoscopically in newborn lambs by electrocoagulating a rim of mucosa. Four weeks later, all had 20 to 90% occlusion documented bronchoscopically. Control animals were found to have dense submucosal fibrosis in the cricoid area. Remaining experimental animals were treated with: (1) electrosurgical resection; (2) cryosurgical treatment; (3) Neodymium-yag (Nd:Yag) laser at 20 watts; (4) Nd:Yag laser with 40 watts; or (5) carbon dioxide laser at 10 watts. Animals from each group were sacrificed at 5 and 30 days postresection and the tracheas were examined grossly and microscopically. Animals sacrificed at 30 days postresection were bronchoscoped at weekly intervals. Cryosurgical and electrosurgical resection resulted in 1-3 mm of thermal damage adjacent to the margin of resection at 5 days post-treatment. Mucosal ingrowth and healing were rapid and there was no development of stenosis or damage to underlying structures. Use of the Nd:Yag laser resulted in 10-20 mm of surrounding damage in animals sacrificed at 5 days. At 30 days posttreatment, there was mucosal healing but extreme underlying damage and redevelopment of stenosis at the level of treatment. The carbon dioxide laser-treated animals showed thermal damage present up to 2 mm in depth from resected areas at 5 days post-treatment. Mucosal regeneration proceeded rapidly. This study indicates that electrosurgical and cryosurgical resection for experimental subglottic stenosis create minimal thermal damage and are associated with comparably acceptable rates of mucosal ingrowth and healing. The carbon dioxide laser created comparable to slightly decreased thermal damage but suffers at present from lack of optimal visualization of the subglottic lesion.

Animals↗
PubMed1979

Hydrophobic esters of cellulose: properties and applications in biochemical technology.

We have investigated the utility for enzyme immobilization of several hydrophobic cellulose esters, as a function of solvent composition, extent of esterification, and enzyme. Phenoxyacetyl cellulose was also used for immobilization of rat liver microsomes, hydrophobic chromatography of proteins, and removal of Triton X-100 from protein solutions. Phenoxyacetyl groups esterified to cellulose were much less subject to enzymatic hydrolysis than soluble phenoxyacetyl esters.

Binding Sites↗
PubMed1978

A technique for the direct observation of the unanesthetized fetal sheep.

A method is described for the chronic implantation of a lucite window in the uterus of a pregnant ewe which allows direct access to the amniotic fluid compartment in the unanesthetized state. The window can be directly connected to an extrauterine viewing compartment allowing repeated observations and measurements of physiologic function. The compartment also provides an easy method of changing the fetal environment.

Animals↗
PubMed1975

Hospital insomnia.

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Hospital Design and Construction↗