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Biomedical subjects

D Johnson

Publications and source records attributed to D Johnson.

At least 631 records · Page 35Linked to original sources
PubMed1983

The vascular supply to the skin: an anatomical and physiological reappraisal--Part II.

The subcutaneous vascular system demonstrated in the first part of this study augments skin flap survival when included within human abdominal flaps. Flaps with larger subcutaneous vessels will survive to a greater length than flaps supplied solely by the subdermal plexus. Knowledge of the subcutaneous vascular system is applicable to breast reduction, subcutaneous mastectomy, and abdominal lipectomy.

Abdominal Muscles↗
PubMed1983

Evaluation of the effect of nonlinear kinetics on dosage adjustments of theophylline.

The pharmacokinetics of theophylline at two different dosage levels were studied in six adult volunteers. The subjects were allowed to reach steady-state serum concentrations of theophylline after 7 days of administration of a sustained-release oral product. There was a statistically significant decrease (p = 0.03) in the total body clearance (TBC) of theophylline at the higher dosage level. At a daily dose of 10.6 mg/kg/day, the mean TBC was 0.76 ml/min/kg, whereas at a dose of 15.7 mg/kg/day the TBC averaged 0.68 ml/min/kg. For two of the subjects, a linear increase in serum concentrations occurred with increasing doses. The remaining four subjects showed a saturation of the elimination processes at the higher dosage. The apparent maximum velocity (Vmax) calculated in these subjects averaged 2,923 mg/day. The mean Michaelis-Menten constant (Km) was 23.70 micrograms/ml. Computer-generated serum concentrations produced by a linear increase in doses predicted toxic concentrations of theophylline in two of the six subjects. The results suggest caution in employing a linear model for the individualization of theophylline therapy.

Administration, Oral↗
PubMed1983

Acute mountain sickness, antacids, and ventilation during rapid, active ascent of Mount Rainier.

A double-blind randomized study of 45 climbers on Mt. Rainier was conducted to test the effectiveness of antacids in preventing acute mountain sickness. All 45 climbed to 3353 m, and 31 continued to the summit. Ten climbers listed acute mountain sickness as the reason for not attaining the summit. Of symptoms monitored throughout the climb, neither headache, nausea, dizziness, pounding heart, nor shortness of breath differed in severity between antacid-treated and placebo-treated groups. In both groups vital capacity decreased significantly with ascent (p less than 0.05), while peak flow (p less than 0.005) and minute ventilation (p less than 0.001) increased significantly. The 7 climbers with the most severe AMS symptom scores above 4000 m had significantly lower peak flow at sea level prior to ascent compared with the other 25 climbers who completed sea level tests (p less than 0.005). The results of this study fail to document efficacy for antacid use for the prevention of acute mountain sickness.

Adult↗
PubMed1982

Transcatheter intraarterial infusion of chemotherapy in advanced bladder cancer.

Bilateral internal iliac artery infusion of chemotherapeutic agents in patients with advanced bladder carcinoma, Stage D, resulted in a 50% response or greater in nine of 15 patients with a median survival, thus far, of 52 weeks. Hematuria was controlled in eight of ten patients, and pain was relieved in 12 of 15 patients. Three additional patients were treated as adjuvants after their residual tumor was removed surgically or irradiated before chemotherapy. Cis-diamminedichloroplatinum (CDDP) was infused at a dose of 80--120 mg/m2 over a 24-hour period. When CDDP failed or in the presence of impaired renal function, a combination of 5-fluorouracil (5-FU) infused intraarterially while Adriamycin and mitomycin C were delivered intravenously, salvaged two patients. Complications were tolerable, consisting of transient acute tubular necrosis in two patients, a lower extremity embolus in one, and skin reactions due to 5-FU in two patients.

Adult↗
PubMed1982

Stress management training for women on public assistance.

A life-coping skills training package for women supported by public assistance was designed to enhance self-esteem and teach life planning and stress management strategies. Ten weeks of training resulted in significant changes in scores on measures reflective of psychological distress, depression, anxiety, inadequacy, self-confidence, and ego strength. A rationale for the impact of the training is suggested.

Adaptation, Psychological↗
PubMed1982

Human T cell growth factor (TCGF) produced by repeated stimulation of non-adherent human lymphocytes.

T cell growth factor (TCGF) has become a valuable means of maintaining T lymphocytes in long-term culture and of studying T cell function. Numerous problems have been met in the production of TCGF of consistently good quality and in the maintenance of human T cell lines over long periods. We have investigated optimal conditions for TCGF production, and simplified assay systems for TCGF activity. The best TCGF production was obtained by short-term treatment with high concentrations of phytohemagglutinin (PHA). The TCGF producing lymphocytes could be re-used for TCGF production up to 1 month after the first treatment course. Human cultured T cell lines, fresh lymphocytes, short-term PHA stimulated lymphocytes and cultured marmoset T lymphocyte lines were all used for assay of TCGF. We recommend PHA stimulation of human lymphocytes for this assay on a routine basis, comparing results with a standard TCGF batch and calculating a growth index. Adherent cells impair TCGF production. Optimal TCGF production was seen when lymphocyte preparations without adherent cells from different donors were used.

Animals↗
PubMed1982

Surgical division of right and left free wall accessory atrioventricular electrical connections in a child with incessant supraventricular tachycardia.

A child with Wolff-Parkinson-White syndrome developed incessant supraventricular tachycardia refractory to medical therapy and countershocks. Supraventricular tachycardias incorporating both right and left free wall accessory atrioventricular electrical connections were demonstrated. The more frequent, broad complex tachycardia utilised both the accessory connections and was independent of the atrioventricular node. The less frequent, narrow complex tachycardia utilised the atrioventricular node for anterograde conduction and the left sided accessory connection for retrograde conduction. Surgical division of the accessory connections restored normal sinus rhythm and eliminated supraventricular tachycardia.

Atrioventricular Node↗
PubMed1982

A radioimmunoassay for the myelin-associated glycoprotein.

The myelin-associated glycoprotein (MAG) was purified from rat brain and radioiodinated with Bolton-Hunter reagent for use in a double-antibody radioimmunoassay. The conditions of the assay were adjusted to measure between 2 and 30 ng of MAG. The antigenic sites of MAG in tissue samples were exposed by solubilization in 1% (wt/vol) sodium dodecyl sulfate (SDS), and the final assay was done in a mixture of 0.25% SDS and 0.25% Triton X-100. The presence of the Triton X-100 overcame the inhibitory effect of SDS alone on the immune reactions. Application of the assay to whole homogenates of developing rat brain revealed the expected increase of MAG with the progression of myelination. Adult brain homogenate and purified myelin contained 2.7 and 7.4 micrograms of MAG/mg protein, respectively. Sciatic nerve contained a lower level of MAG, and cross-reacting material was not detected in nonneural tissues. This assay makes possible for the first time the analysis of MAG in whole tissue without prior myelin isolation or glycoprotein separation.

Aging↗
PubMed1982

The effect of some varying lipid A structures on the inhibition of fibrillogenesis in basement membrane collagen.

Acid soluble basement membrane collagen (ABMC) was prepared by extraction of the anterior lens capsules from bovine calf eyes in 0.5 M acetic acid in the presence of the protease inhibitors leupeptin and pepstatin. Thermal aggregates formed from soluble basement membrane collagen were facilitated by heating (28 degree C) the collagen solutions in 0.15 M phosphate buffer. The effects of endotoxins derived from Salmonella minnesota R595, Chromobacterium violaceum an Rhodopseudomonas viridis on the assembly af basement membrane collagen were ascertained by analysis of turbidity curves (340 nm) obtained during aggregation in vitro. All of the endotoxins tested were noted to inhibit the final level of turbidity and to prolong the lag period for thermal assembly. Plotting the increase in turbidity against the logarithm of time of analyzing the turbidity curves as first-order reaction indicated that what was altered was the rate of assembly of fibrils in collagen treated with endotoxin, rather than the mechanism of assembly of these fibrils. These conclusions are supported by Arrhenius plots of basement membrane aggregations in vitro in the presence and absence of endotoxins.

Animals↗
PubMed1982

2-bromo-alpha-ergocryptine (CB-154) and tamoxifen (ICI 46,474) induced suppression of the genesis of mammary carcinomas in female rats treated with 7,12-dimethylbenzanthracene (DMBA): a comparison.

Daily treatment of female Sprague-Dawley rats with CB-154 (prolactin suppressor) or Tamoxifen (estrogen antagonist) for 33 days before and after 7,12-dimethylbenzanthracene (DMBA) administration reduced (p less than 0.005) the incidence of mammary carcinomas by 58 and 49%, respectively. A combination of CB-154 and Tamoxifen further reduced (p less than 0.005) mammary carcinoma incidence by an additional 50-59%. Treatment with Tamoxifen for 66 days beginning 33 days after carcinogen treatment reduced (p less than 0.05) the incidence of mammary carcinomas by 65%; CB-154 treatment, during the same time period, did not significantly effect the final yield of mammary carcinomas. The combination of Tamoxifen and CB-154 was comparable to Tamoxifen alone in suppressing the incidence of mammary carcinomas in the latter study. These results demonstrate a substantial suppressive and synergistic effect of Tamoxifen and CB-154 in the initiating phases of mammary carcinogenesis while in the early promoting phases of this oncogenic process, short-term treatment with Tamoxifen was superior to CB-154 treatment; no synergism between these clinically important compounds was observed.

9,10-Dimethyl-1,2-benzanthracene↗