Search PubMed⌕ Search

Biomedical subjects

W T Johnson

Publications and source records attributed to W T Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1983

Spectrophotometric analysis of microleakage in the fine curved canals found in the mesial roots of mandibular molars.

Mesial roots from forty human mandibular first and second molar teeth were randomly assigned to two groups and obturated with laterally condensed gutta-percha or silver cones. Each group was divided into two subgroups. The first subgroup for each group consisted of specimens that had two canals with a common foramen. The second subgroup consisted of specimens with two canals and separate foramina. All specimens were obturated and exposed to 2 percent methylene blue dye at 37 degrees C. for a period of 30 days. A dye-recovery, spectrophotometric method was used to evaluate the apical microleakage. Results indicated no statistically significant difference in leakage between the groups or subgroups.

Dental Leakage↗
PubMed1983

Hypersensitivity to procaine, tetracaine, mepivacaine, and methylparaben: report of a case.

The patient who comes for dental treatment with a history of hypersensitivity to local anesthetics is often denied the benefits of adequate pain control during dental therapy. Ninety percent of the patients challenged by Incaudo and associates were being evaluated because they needed local anesthesia for dental treatment. These same patients may some day need local anesthetic agents for minor surgery or for the treatment of cardiac arrhythmias. For those cases in which an allergic reaction is suspected, consultation with an allergist may prove beneficial to the patient by providing information and a local anesthetic that the patient can receive safely for both medical and dental needs.

Anesthesia, Dental↗
PubMed1982

Tissue uptake of zinc in rats following the administration of zinc dipicolinate or zinc histidinate.

Tissue uptake of zinc was determined in rats fed a low zinc diet (less than 1 ppm Zn) and an adequate zinc diet (20 ppm Zn) following the intramuscular injection of either zinc dipicolinate (ZnPA2) or zinc histidinate (ZnHis). Significant differences were observed when dietary and treatment effects on zinc uptake were compared in pancreas, duodenum, jejunum, ileum, kidney, and liver. Zinc uptake by the pancreas was higher in rats fed adequate zinc than in rats fed low zinc regardless of which zinc complex was injected, suggesting that the pancreas has a role in zinc excretion. Since ZnHis was more readily taken up than ZnPA2 by the pancreas of rats on the zinc-adequate diet, zinc chelated by histidine may be more readily excreted than zinc chelated by picolinic acid. No differences in zinc uptake were observed in the intestinal segments from rats fed low zinc compared to rats fed adequate zinc. However, in rats fed low zinc, ZnPA2 was more readily taken up than ZnHis by all intestinal segments implying that zinc chelated by picolinic acid may be more available for storage or utilization by the small intestine than zinc chelated by histidine. Also, the ileum had the highest zinc uptake regardless of which zinc complex was injected. Since the ileum has the largest population of Paneth cells, and high zinc uptake observed in this segment of the small intestine suggests a role for Paneth cells in zinc homeostasis.

Animals↗
PubMed1979

Stimulation by polyamines of carbamylphosphate:glucose phosphotransferase and glucose-6-phosphate phosphohydrolase activities of multifunctional glucose-6-phosphatase.

The effects of added polyamines on carbamylphosphate (carbamyl-P):glucose phosphotransferase and glucose-6-phosphate (Glc-6-P) phosphohydrolase activities of rat hepatic D-Glc-6-P phosphohydrolase (EC 3.1.3.9) of intact and detergent-treated microsomes have been investigated. With the former preparation, in the presence of 1.4 mM phosphate substrate and 90 mM D-glucose (phosphotransferase), 1 mM spermine, spermidine, and putrescine activated Glc-6-P phosphohydrolase 67%, 57%, and 35%, respectively. Carbamyl-P:glucose phosphotransferase, under comparable conditions, was activated 57%, 34%, and 18%. NH+4 (0.25--5.0 mM) produced at best but a minor activation (0--14%), while poly(L-lysine) (Mr = 3400; degree of polymerization 16) equimolar relative to other polyamines with respect to ionized free amino groups activated the hydrolase 358% and the transferase 222%. Treatment of microsomes with the detergent deoxycholate reduced, but did not abolish, polyamine-induced activation. The stimulatory effects of polyamines persisted in the presence of excess catalase, indicating their independence from H2O2 formation; and were eliminated in the presence of Ca2+. Kinetic analysis revealed that all tested polyamines decreased the apparent Michaelis constant values for carbamyl-P and Glc-6-P, but had no effect on the Km for glucose. Poly(L-lysine) increased the V value for both Glc-6-P phosphohydrolase and apparent V values for phosphotransferase extrapolated to infinite concentrations of either carbamyl-P or glucose. The other tested polyamines elevated only this last velocity parameter. It is proposed that a major mechanism by which polyamines activate glucose-6-phosphatase-phosphotransferase is through their electrostatic interactions with phospholipids of the membrane of the endoplasmic reticulum of which this enzyme is a part. Conformational alterations thus induced may in turn affect catalytic behavior. It is suggested that polyamines, or similar positively charged peptides, might participate in the cellular regulation of synthetic and hydrolytic activities of glucose-6-phosphatase.

Ammonium Chloride↗
PubMed1979

The acrodermatitis enteropathica-like syndrome.

An acrodermatitis enteropathica-like syndrome occurred as a result of severe bowel disease and the use of zinc-deficient hyperalimentation regimens. Emphasis is placed on early and adequate zinc replacement to effectively prevent or reverse this entity.

Acrodermatitis↗
PubMed1979

Herpes zoster during pregnancy.

Herpes zoster has rarely been noted to occur during pregnancy. We report the case of a woman at 37 weeks' gestation who developed herpes zoster and 3 weeks later delivered a normal infant. A 6-month follow-up has revealed no sequelae in the child. Pertinent clinical aspects of herpes zoster and a review of the literature indicating a favorable prognosis for infants exposed in utero are presented.

Adult↗
PubMed1979

Cutaneous chylous reflux. The weeping scrotum.

The cutaneous lesions associated with reflux of lymphatic fluid and chyle from the skin have received little attention in the dermatologic literature. We describe a patient with such lesions, and discuss the clinical, histopathologic, and lymphangiographic manifestations. We review the classification of lymphedema and the commonly seen cutaneous lesions.

Adolescent↗
PubMed1979

Unilateral blepharochalasis.

True blepharochalasis occurring in young adults and associated with recurrent bouts of eyelid swelling and eventual lid laxity is an uncommon entity. We report the case of an 18-year-old woman who had a nine-year history of unilateral blepharochalasis. A skin biopsy specimen that showed the absence of stainable elastic tissue confirmed the clinical impression, and appropriate surgical correction was carried out.

Adolescent↗
PubMed1978

Clinical syndrome of chemotaxis defect, infections, and hyperimmunoglobulinemia E. A case report.

A 17-year-old girl had a clinical syndrome that consisted of neutrophil chemotaxis defect, recurrent bacterial infections, and hyperimmunoglobulinemia E. Neutrophil chemotaxis was quantitated by a radioassay technique that used 51Cr-labeled neutrophils and a double micropore filter chemotaxis chamber. A table of the features of other cases of this syndrome is presented. Since ten of the 13 patients who are described had a chronic eczematoid dermatitis, we suggest that this may be a fourth feature of this syndrome. Red hair and fair skin were not consistent findings in these patients. In the evaluation of patients with chronic, recurrent bacterial infections of the skin of undetermined origin, we recommend determination of serum IgE levels. If IgE is found to be elevated, one should consider the presence of this syndrome, and neutrophil chemotaxis should then be examined.

Adolescent↗