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Biomedical subjects

R E Taylor

Publications and source records attributed to R E Taylor.

At least 91 records · Page 5Linked to original sources
PubMed1987

Polymorphous low-grade adenocarcinoma of the tongue.

Primary adenocarcinoma of the oral cavity is an infrequently encountered problem. Adenocarcinomas are distinctive lesions which can be subclassified according to their tissue growth patterns or histomorphology. The polymorphous low-grade adenocarcinoma of the oral cavity is usually of minor salivary gland origin. We present an unusual case of polymorphous low-grade adenocarcinoma of the tongue and add this case to the existing two previous reports in the literature. A review of the current literature concerning this tumor is included. Treatment presently consists of complete local excision followed by radiation therapy.

Adenocarcinoma↗
PubMed1987

Post-tonsillectomy bleeding: an evaluation of risk factors.

While tonsillectomy is usually a safe operation, it is always accompanied by the risk of immediate postoperative bleeding. Despite continued efforts to eliminate this problem, it remains a persistent risk. In reviewing 775 consecutive cases of tonsillectomy, immediate postoperative bleeding occurred in 21 (2.7%). Diagnostic, demographic, hematologic, hemodynamic and surgical management factors were evaluated. The role of local anesthesia for tonsillectomy was also examined. Postoperative bleeders were more likely to have abnormal preoperative clotting studies, greater elevations of their mean postoperative blood pressures, and unusual surgical indications. Local anesthetic cases were shorter, had less intraoperative bleeding and were not associated with greater postoperative bleeding. We conclude that local anesthesia is safe and efficient and that identifiable factors are associated with primary post-tonsillectomy bleeding. An awareness of these factors can help identify potential postoperative bleeders.

Adolescent↗
PubMed1987

Comparative efficacy and safety of immediate-release and controlled-release hydralazine in black hypertensive patients.

Twenty-nine black hypertensive patients were randomized to treatment with controlled-release hydralazine capsules administered BID or QD, or immediate-release hydralazine tablets administered TID, for at least four weeks in a double-blind, parallel study. Hydralazine was begun after a two-week to four-week period in which blood pressure was not adequately controlled with diuretics alone. Each patient initially received 75 mg/day of the assigned drug. The dosage could be increased to 150 or 300 mg/day at weekly intervals if sitting diastolic blood pressure was not adequately controlled (greater than 90 mmHg). A beta-blocker (80 mg/day of nadolol) was added only for patients who had beta-blocker-responsive adverse effects that could not be controlled otherwise. Nine patients were considered unevaluable because of protocol violations or withdrawal from the study before completion of four weeks of treatment, primarily because of adverse effects. Twenty patients were included in the efficacy evaluation. Controlled-release hydralazine BID produced statistically significant mean falls from baseline in sitting diastolic blood pressure and in standing systolic blood pressure and an almost significant drop in standing diastolic blood pressure. Although the other two treatment groups also had substantial falls in all blood pressure measurements, the changes from baseline were not statistically significant. No significant difference in response was noted between patients who received a beta-blocker and those who did not. There were no statistically significant differences among the three treatment groups in incidence and severity of adverse effects or electrocardiographic abnormalities. A statistically, but not clinically, significant fall in hemoglobin, hematocrit, and red blood cell count was observed in all three treatment groups.

Adult↗
PubMed1986

Lactate dehydrogenase as a marker for testicular germ-cell tumours.

One hundred and eighty-four patients with testicular germ-cell tumours, 92 with seminoma and 92 with non-seminomatous germ-cell tumours (NSGCT) had total lactate dehydrogenase (LD) assay performed at the time of initial staging following orchidectomy. The proportion of patients with elevated plasma LD and the mean plasma LD increased with advancing stage and increasing tumour bulk for both seminoma and NSGCT. Of patients receiving cytotoxic chemotherapy, 87.5% with seminoma and 63% with NSGCT had elevated plasma LD with subsequent levels reflecting regression or progression of disease. Elevated plasma LD levels were seen in four of seven seminoma, and in 18 of 30 NSGCT patients relapsing after primary treatment. The LD assay provides useful information, and complements the routine measurement of alphafetoprotein (AFP) and beta human chorionic gonadotrophin (beta hCG) in the management of patients with testicular germ-cell tumours.

Antineoplastic Agents↗
PubMed1986

Influence of computed tomography scanning and lymphography on the management of testicular germ-cell tumours.

Seventy-eight patients with seminoma and 66 patients with teratoma had computed tomography (CT) of the thorax and abdomen performed as part of initial staging following orchidectomy. Four of 65 (6%) seminoma and 13 of 66 (20%) teratoma patients were upstaged by the addition of CT scanning. No seminoma patients with Stage I disease according to abdominal CT and lymphography had an abnormal thoracic CT scan. Seven of 52 (13%) seminoma and 4 of 21 (19%) teratoma patients who were Stage I according to the CT scan had their staging altered by lymphography. CT was of particular value for defining the exact extent and bulk of metastatic disease prior to and following chemotherapy and radiotherapy, prior to surgical excision of residual disease following chemotherapy, and for investigating potential sites of disease relapse. For all patients with teratoma, we recommend CT of the thorax and abdomen, with bipedal lymphography for those with normal CT scans. For seminoma patients, we suggest lymphography followed by abdominal CT and if either is abnormal, thoracic CT.

Dysgerminoma↗
PubMed1986

Bilateral testicular plasmacytoma.

A case is reported of a 55-year-old man with asynchronous bilateral testicular plasmacytoma. Despite chemotherapy and radiotherapy he died seven and a half years after the original diagnosis of testicular plasmacytoma, and 13 months after developing evidence of disseminated myeloma. The testicular plasmacytomas may have arisen as a result of seeding from a systemic myelomatous process.

Humans↗
PubMed1986

Effect of hydrogen ion concentration on corticosteroid secretion.

The direct effects of changes in extracellular hydrogen ion (H+) concentration on corticosteroid secretion under basal and ACTH-stimulated conditions were studied in isolated, perfused canine adrenal glands. Changes in extracellular H+ concentration were produced by altering either PCO2 or [HCO-3] of the Krebs-bicarbonate perfusate. Alkalosis markedly inhibited ACTH-stimulated aldosterone secretion. Moreover, within the range of pH from 7.19 to 7.85, there was a positive correlation between H+ concentration and the fractional secretion of aldosterone but a negative correlation between H+ concentration and the fractional secretion of corticosterone and 18-hydroxycorticosterone in response to ACTH. In contrast, neither acidosis nor alkalosis had a significant, direct effect on basal or ACTH-stimulated cortisol secretion. We conclude that 1) H+ concentration modulates the stimulatory effect of ACTH on aldosterone secretion by a direct action on the adrenal cortex, 2) acid-base disturbances are specific to the zona glomerulosa of the canine adrenal gland, and 3) H+ concentration may influence events occurring late in the pathway for aldosterone biosynthesis.

18-Hydroxycorticosterone↗
PubMed1986

Effect of hydrogen ion concentration on aldosterone secretion by isolated perfused canine adrenal glands.

The direct effects of changes in extracellular hydrogen ion (H+) concentration on aldosterone secretion under basal, angiotensin II- and potassium-stimulated conditions were studied in isolated, perfused canine adrenal glands. Changes in extracellular H+ concentration were induced by altering either the partial pressure of CO2 (pCO2) or the HCO3- concentration of the perfusate. Acid-base disturbances had a more pronounced effect on aldosterone secretion under stimulated than under basal conditions. Increasing H+ concentration enhanced angiotensin II- and potassium-stimulated aldosterone secretion, whereas decreasing H+ concentration markedly inhibited the secretory response to these stimuli. Because changes in H+ concentration, whether produced by varying extracellular pCO2 or extracellular HCO3- concentration, had similar effects on angiotensin II-stimulated aldosterone secretion, the data suggest that H+ concentration per se is the important determinant of the aldosterone secretory rate. Interestingly, during the immediate recovery period from pCO2-induced alkalosis under both angiotensin II- and potassium-stimulated conditions, aldosterone secretion always returned to a value significantly higher than that obtained just before alkalosis. The results of this study demonstrate that changes in extracellular H+ concentration influence the rate of aldosterone secretion, possibly via changes in intracellular pH, by a direct action on the canine adrenal gland. Therefore, when evaluating the control of aldosterone secretion, the acid-base status of the whole animal or of in-vitro adrenal tissue must be considered.

Adrenal Glands↗
PubMed1986

Beta blockers, hypertension, and blacks--is the answer really in?

It has been reported that beta blockers are not effective antihypertensives in black populations. A review of the literature revealed that, for the most part, studies drawing this conclusion were of small sample size, lacked controls, and did not represent the demographics of the US black population. The largest US study (Veterans Administration Cooperative Study) showed propranolol to be effective in at least one half of the black patients, with white patients responding better, but diuretics were more effective in both races. More recent studies show beta blockers with alpha-antagonistic properties to be effective in black hypertensives. The question is raised whether enough data have been analyzed to suggest these drugs are ineffective for black hypertensives.

Adrenergic beta-Antagonists↗
PubMed1986

Characterization of Tritrichomonas foetus antigens, using bovine antiserum.

Tritrichomonas foetus antigens were identified, using the serum of an Angus heifer that had been repeatedly immunized with suspensions of 1 X 10(8) organisms in Freund's complete adjuvant. Antibody activity against T foetus was determined by dot-blot analysis, using horse-radish peroxidase-conjugated anti-bovine immunoglobulin to detect bound antibody. The antiserum contained antibodies against surface and flagellar components of live or fixed T foetus, as determined by use of immunofluorescence. The antiserum reacted with approximately 38 proteins in a pool of 55 to 60 components resolvable by polyacrylamide-gel electrophoresis of T foetus extracts.

Animals↗
PubMed1986

Clinical pharmacokinetics: a simplified approach, Part 2.

Part 1 of this two-part series in clinical pharmacokinetics (J Natl Med Assoc 1985; 77:475-482) introduced the clinician to the basic principles required for rational therapeutic drug management at the bedside. Practical problems were included that demonstrated how these principles could be put to clinical use.In Part 2 the clinical pharmacology of three commonly used drugs (theophylline, digoxin and gentamicin) are discussed, and practical problems are presented to illustrate the use of their pharmacokinetic profiles.

Humans↗
PubMed1986

Visual hallucinations: meaning and management.

Visual hallucinations of low vision patients may serve as indicators of trauma, illness and psychological disturbance or concerns. Routine inquiry about them is suggested and two case illustrations of this procedure are presented. Primary consideration is management of patient anxiety and fear, as well as indications for referral to allied professions. The incidence of hallucinations is very likely under-reported, though detailed exploration of the parameters of hallucinations in the visually impaired population can enhance existing knowledge and often alleviate fears of mental illness.

Blindness↗
PubMed1985

Cleavage of bovine skin type III collagen by proteolytic enzymes. Relative resistance of the fibrillar form.

We have studied the susceptibility of fibrils formed from fetal bovine skin type III collagen to proteolytic enzymes known to cleave within the helical portion of the molecule (vertebrate and microbial collagenase, polymorphonuclear elastase, trypsin, thermolysin) and to two general proteases of broad specificity (plasmin, Pronase). Fibrils reconstituted from neutral salt solutions, at 35 degrees C, were highly resistant to nonspecific proteolysis by general proteases such as polymorphonuclear elastase, trypsin, and thermolysin but were rapidly dissolved by bacterial and vertebrate collagenases at rates of 12-45 mol X mol-1 X h-1. In solution, type III collagen was readily cleaved by each of the proteases (with the exception of plasmin), as well as by the true collagenases, although at different rates. Turnover numbers determined by viscometry at 35 degrees C were: human collagenase, approximately equal to 1500 h-1; microbial (clostridial) collagenase, approximately equal to 100 h-1; and general proteases, 23-52 h-1. In addition it was shown that pronase cleaves type III collagen in solution at 22 degrees C by attacking the same Arg-Gly bond in the alpha 1(III) chain as trypsin. However, like other proteases, Pronase was rather ineffective against fibrillar forms of type III collagen. It was also shown that transition of type III collagen as well as type I collagen to the fibrillar form resulted in a significant gain of triple helical thermostability as evidenced by a 6.8 degrees C increase in denaturation temperature (Tm = 40.2 degrees C in solution; Tm = 47.0 degrees C in fibrils).

Amino Acid Sequence↗
PubMed1985

Sodium channel activation in the squid giant axon. Steady state properties.

Treatment of giant axons from the squid, Loligo pealei, with pronase removes Na channel inactivation. It was found that the peak Na current is increased, but the activation kinetics are not significantly altered, by pronase. Measurements of the fraction of open channels as a function of voltage (F-V) showed an e-folding at 7 mV and a center point near -15 mV. The rate of e-folding implies that a minimum of 4 e-/channel must cross the membrane field to open the channel. The charge vs. voltage (Q-V) curve measured in a pronase-treated axon is not significantly different from that measured when inactivation is intact: approximately 1,850 e-/micron2 were measured over the voltage range -150 to 50 mV, and the center point was near -30 mV. Normalizing these two curves (F-V and Q-V) and plotting them together reveals that they cross when inactivation is intact but saturate together when inactivation is removed. This illustrates the error one makes when measuring peak conductance with intact inactivation and interpreting that to be the fraction of open channels. A model is described that was used to interpret these results. In the model, we propose that inactivation must be slightly voltage dependent and that an interaction occurs between the inactivating particle and the gating charge. A linear sequence of seven states (a single open state with six closed states) is sufficient to describe the data presented here for Na channel activation in pronase-treated axons.

Animals↗
PubMed1985

Restriction endonuclease analysis of bovine herpesvirus 1 DNA and nucleic acid homology between isolates.

Isolates of bovine herpesvirus 1 (BHV-1) are associated with a variety of clinical manifestations. To determine if a single form of BHV-1 was responsible for the different virus-associated diseases or whether subpopulations of various isolates produced different clinical symptoms, studies were initiated to examine the DNA restriction enzyme patterns and nucleic acid homology between virus isolates from respiratory infections and other clinical syndromes. Differences between the genomes of several virus isolates were detected using DNA restriction enzyme analyses. However, nucleic acid hybridization studies of the virus DNAs using filter and liquid hybridization indicated at least a 95% genetic homology between the virus isolates from different types of infections. Additionally, these studies demonstrated that the DNA of BHV-1 had an average molecular weight of 84 X 10(6).

Animals↗