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Biomedical subjects

G Johnson

Publications and source records attributed to G Johnson.

At least 595 records · Page 33Linked to original sources
PubMed1976

The effect of calcium hydroxide and fluorides on human dentine.

With the aid of scanning electron microscopy and microradiography, 45 teeth including 20 contralateral tooth pairs were studied to assess the effect on human dentine of (1) a 1 minute treatment with 3% NaF, (2) a dressing of Ca(OH)2 and (3) a dressing of Ca(OH)2 and CaPO3F after follow-up periods of 2-8 weeks. After NaF treatment the SEM revealed no sign of obliteration of the dentinal tubules, and on microradiograms no indication of increased density could be registered compared to an untreated control area. Under the calcium dressing the SEM revealed in 13 cases out of 20 (5 cases of 11 intrapair comparisons) a varying degree of constriction of the dentinal tubules. Constrictions varied from one tubule to another and ceased approximately 0.1 mm in the dentine. On the microradiograms no significant difference could be registered between untreated dentine and dentine treated with the calcium dressings. Dressings of Ca(OH)2 a combination of Ca(OH)2 and CaPO3F for 2 months, or a 1 minute treatment with a cavity cleaner containing 3% NaF can thus not be considered to result in a reliable obliteration of the dentinal tubules.

Calcium Hydroxide↗
PubMed1975

The phosphorylation region of lysine-rich histone in dividing cells.

N-Bromosuccinimide cleavage of in vivo 32P-labelled lysine-rich histone isolated from rapidly dividing cells has been studied. N-Bromosuccinimide cleaves F1-histone into two fragments, a small N-terminal piece and a larger C-terminal portion. The phosphate-induced microheterogeneity and associated radioactivity which has been linked to cell replication, is found in the carboxyterminal fragment, No phosphorous is found associated with the amino-terminal fragment when histone phosphorylation is associated with cell division. The specific tryptic phosphopeptides obtained from in vivo labelled F1 are clearly different from those obtained from in vitro incubations of free F1-histones and cytoplasmic protein kinase.

Animals↗
PubMed1975

Use of radionuclide imaging in the early diagnosis and treatment of renal allograft rejection.

Data are presented on the clinical application of radionuclide imaging to evaluate changes in cadaver transplant function in the immediate postoperative period. The method uses orthoiodohippuric acid (hippuran) administered IV, with scintillation imaging, and curve analysis by a digital computer. An initial study is always obtained 24 hours after transplantation. Serial studies are then obtained, as needed, to interpret the clinical course. Selected cases are presented which illustrate the use of this protocol in various clinical settings. In the oliguric patient serial studies have been of particular value. They have identified ATN so that over-enthusiastic treatment for rejection could be avoided. They have also identified acute rejection complicating ATN so that high dose steroid therapy could be administered appropriately. In the non-oliguric patient they have frequently contributed to the early diagnosis of acute rejection, and they have been useful in monitoring the effect and duration of treatment for severe rejection crisis. It is concluded that radionuclide imaging studies, when carefully applied and interpreted, are a valuable adjunct to the management of patients in this complex clinical setting.

Acute Disease↗
PubMed1975

Population differences of aspartate aminotransferase and peptidase in the bay mussel Mytilus edulis.

This investigation has demonstrated considerable heterogeneity among populations and some heterogeneity within populations in the distribution of alleles at two variant loci of Mytilus edulis. Although the causes of this variation remain obscure, some speculations have been made on the basis of available data. A cline for aspartate aminotransferase (AAT) alleles has been observed on the Pacific Coast. An immigration model has been proposed to explain the atypical ecological and genetic characteristics of large mussels found on Amchitka Island, Alaska. Marked differences were found in the distribution of peptidase alleles among collections from Southern California, the North Pacific Ocean, and New Jersey. Deviations from random distribution of phenotypes observed in comparisons made between large and small mussels from the New Jersey collection may reflect selection operating on these loci in this population.

Alleles↗
PubMed1975

Erythrocyte filterability and lysosomal enzymes in patients requiring cardiopulmonary bypass.

Erythrocyte filterability, an index of deformability, and lysosomal enzyme activity were studied in 34 patients requiring cardiopulmonary bypass. In addition fresh human erythrocytes were analyzed after incubation for filterability changes after exogenous lysosomal enzymes were added to the suspension medium. The results showed statistically significant elevations of the filterability index (decrease in filterability of the red cells) after 10 minutes on cardiopulmonary bypass as well as postoperatively. Likewise cathepsin D concentration after 10 minutes of cardiopulmonary bypass of 8.4 plus or minus 0.8 U. was significantly elevated over the preoperative level of 5.3 plus or minus 0.7 U. Furthermore, the pump prime was found to have the highest filterability index as well as concentration of cathepsin D. Supporting our hypothesis that lysosomal enzymes may be a factor affecting erythrocyte integrity was the elevation of the filtration index to 10.5 plus or minus 0.3 U. during incubation with exogenous lysosomal enzymes compared with the control index of 9.0 plus or minus 0.2 U. This stduy implies that the pump prime should be an area of further investigation if alterations of erythrocyte filterability (deformability) and lysosomal enzymes during extracorporeal circulation are shown to have clinical importance.

Animals↗