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Biomedical subjects

T Edwards

Publications and source records attributed to T Edwards.

30 records · Page 2Linked to original sources
PubMed1993

Effect on verapamil on ventricular function: studies in denervated human heart.

Verapamil has complex influences on ventricular function owing to its direct myocardial effects, vasodilation, and reflex activation of the sympathetic nervous system. To investigate the direct myocardial effects of verapamil in humans independent of reflex sympathetic stimulation, we administered the drug to 13 recent heart transplant recipients with denervated ventricles. Hemodynamics and radionuclide angiograms were recorded at baseline, with altered loading conditions, and after intravenous (i.v.) verapamil (median dose 4 mg). Left ventricular (LV) systolic and diastolic function was analyzed by systolic pressure-volume relations (SPVR) and peak filling rate (PFR), respectively. Verapamil caused a decrease in blood pressure (BP) and heart rate (HR) with increases in right atrial pressure (RAP 6 +/- 3-8 +/- 3, p < 0.01) and pulmonary artery wedge pressure (PAWP, 9 +/- 3-11 +/- 3 mm Hg, p < 0.01) pressures. LV ejection fraction (EF) decreased (69 +/- 7-66 +/- 8%, p < 0.02) in association with an increase in LV end-systolic counts (3.45 +/- 1.27 to 4.72 +/- 1.78 kcts, p < 0.001). In 11 of 13 patients, the SPV point after verapamil administration was decreased from the line established during altered loading conditions. PFR (4.05 +/- 0.81 to 4.11 +/- 0.76 EDV/s) was unchanged. In the denervated ventricle, verapamil has negative chronotropic and inotropic effects with minimal effects on PFR.

Adult↗
PubMed1992

A technique for postoperative irradiation of carcinomas of the larynx and hypopharynx.

Postoperative radiation is commonly employed for advanced lesions of the larynx and hypopharynx which have undergone a laryngectomy. It is technically difficult to achieve a homogeneous distribution of irradiation throughout the treatment volume because of the marked variation in contour across the treated area. We have described a technique which employs a 15 degrees lateral kick-out of the treatment table and a 15 degrees gantry angle above the horizontal for each of two lateral fields. This technique has certain advantages over other techniques previously described in the literature. By adding a gantry angle of 15 degrees above the horizontal to the kick-out lateral position of the table, we have found that we were able to decrease the amount of irradiation to the shoulder, to improve the dose to the posterior superior mediastinum, to lower the applied dose, and to avoid a hot spot overlying the spinal cord in the superior posterior portion of the field. This technique is particularly useful in patients who lack the flexibility to move their shoulders posteriorly and inferiorly.

Carcinoma, Squamous Cell↗
PubMed1992

Alterations in the methylation of membrane phospholipids in the uterus and post-implantation embryo following exposure to teratogenic doses of alcohol.

The intragastric administration of alcohol to pregnant mice at 3.0 g/kg body weight, but not at 0.5 or 1.5 g/kg body weight, adversely influenced embryonic growth and increased the rate of methyl group incorporation from S-adenosyl-L-[methyl-3H]methionine into uterine endometrial plasma membrane phospholipids. These changes involved phosphatidylcholine, phosphatidyldimethylethanolamine, and phosphatidylmonomethylethanolamine when the alcohol was acutely administered, but only phosphatidylcholine when the drug was given in a semi-chronic regime. Similar alterations were not detected in post-implantation embryos exposed to alcohol either in vitro or in vivo. The results suggest that maternal exposure to alcohol during early post-implantation pregnancy can alter the pattern of phospholipid methylation in the uterus, but not in the embryo, which may facilitate biochemical changes that adversely influence the ability of the maternal system to support embryonic development.

Animals↗
PubMed1991

Effects of acute alterations in left ventricular loading conditions on peak filling rate in the denervated (transplanted) ventricle.

Peak filling rate is an indicator of left ventricular (LV) diastolic function. It is influenced by heart rate, loading conditions, sympathetic nervous system activity, ejection fraction and other factors. To determine the effect of altered loading conditions on peak filling rate, independent of heart rate and sympathetic nervous system activity, 12 patients were studied 3 weeks after orthotopic heart transplantation. Plasma catecholamine level, heart rate and ejection fraction were not changed by any maneuver. Nitroglycerin caused a decrease in pulmonary artery wedge pressure (9 +/- 2 to 6 +/- 1 mm Hg, p less than 0.001) and in absolute peak filling rate (46.0 +/- 3.0 to 42.8 +/- 2.5 kcts/s, p less than 0.01), but no change in normalized peak filling rate. Volume infusion increased pulmonary artery wedge pressure (9 +/- 2 to 12 +/- 2 mm Hg, p less than 0.001) and absolute peak filling rate (46.0 +/- 3.0 to 51.5 +/- 5.3 kcts/s, p less than 0.01), but peak filling rate normalized to stroke volume was unchanged. During nitroglycerin and volume infusions, there was a high correlation between changes in pulmonary artery wedge pressure and absolute peak filling rate (r = 0.82, p less than 0.001). With normalization of peak filling rate, these variables correlated less well. With methoxamine, 4 patients demonstrating systolic dysfunction had a decrease in absolute and normalized peak filling rate despite a large increase in pulmonary artery wedge pressure. The other 8 patients without systolic dysfunction had an increase in pulmonary artery wedge pressure with increased absolute but unchanged normalized peak filling rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1991

The effect of H-2 region and genetic background on hormone-induced ovulation rate, puberty, and follicular number in mice.

We have examined the effects of major histocompatibility (H-2) haplotypes and genetic background (all loci other than the H-2 region) on hormone-induced ovulation rate in congenic strains of mice. In comparison with the H-2a haplotype, the H-2b haplotype increased hormone-induced ovulation rate 92% on the A/J (A) genetic background. However, H-2 haplotype did not affect hormone-induced ovulation rate on the C57BL/10J (C57) genetic background. The H-2b-linked gene(s) increased hormone-induced ovulation rate on the A/J genetic background largely by (1) enhancing the maturation of follicles in response to pregnant mare's serum gonadotrophin (PMSG) and (2) altering the stages of follicular development which can be induced to ovulate in response to human chorionic gonadotrophin (hCG). The observed effects of H-2 on hormone-induced ovulation rate were not explained by differences in the timing of puberty, the number of follicles present in untreated females, or the incidence of follicular atresia. The effect of genetic background on hormone-induced ovulation rate was much greater than was the effect of the H-2 region. We found that hormone-induced ovulation rate was five- to six-fold higher on the C57 genetic background than on the A genetic background. The C57 genetic background increased hormone-induced ovulation rate by (1) enhancing the induction of follicular maturation in response to gonadotropins and (2) by reducing the incidence of follicular atresia.

Animals↗
PubMed1980

Characterization of Bacteroides asaccharolyticus and B. melaninogenicus oral isolates.

Experiments were designed to characterize a number of oral "pigmented" Bacteroides isolates with regard to their pathogenicity in an experimental model system and a number of other properties. T these include fatty acid determination, hemagglutination studies, collagenase and protease activities, and vitamin K dependency. Oral B, asaccharolyticus and B, melaninogenicus isolates differed from one another in phenylacetic acid production, hemagglutination, collagenase activity, and pathogenicity. All B. asaccharolyticus were found to be pathogenic in the vivo mixed infection model and this property could be correlated with biochemical enzymatic activities.

Adult↗
PubMed1977

Spectinomycin-resistant Neisseria gonorrhoeae.

Neisseria gonorrhoeae resistant to high levels of spectinomycin (more than 2,048 microng/ml), were isolated from specimens obtained from a patient with urethritis. The bacterial resistance to spectinomycin is probably due to ribosomal changes that are a result of a chromosomal mutation. If spectinomycin fails to cure gonorrhea, spectinomycin resistance should be considered.

Adult↗
PubMed1975

New method for the isolation and identification of methanogenic bacteria.

A new technique is reported for the rapid growth and detection of methanogenic bacteria by using petri plates. The method employs an anaerobic glove box containing an inner chamber with separate gas-flushing facilities. The numbers of methanogenic bacteria recovered from domestic sewage sludge are comparable to those recovered by other methods. The methanogenic organisms isolated from sludge include Methanosarcina, Methanospirillum, Methanobacterium strain M.o.H., and Methanobacterium formicicum. Identification of colonies containing methanogenic bacteria is facilitated by taking advantage of the unique fluorescence properties of these organisms. Colonies as small as 0.5 mm can be detected by exposing them to long-wave ultraviolet light.

Anaerobiosis↗
PubMedDate not supplied

A preliminary evaluation of the Gonozyme test.

Gonozyme is a solid-phase enzyme immunoassay that detects antigens of Neisseria gonorrhoeae in clinical specimens. The test was 100% sensitive and 96.8% specific when applied to 71 urethral specimens from men with symptomatic urethritis, and 89.5% specific for 19 urethral specimens from men examined after eradication of gonorrhea by antibiotics. For cervical specimens obtained before therapy from 368 women with gonorrhea, the Gonozyme test had a sensitivity of 88.5% and a specificity of 94.3%. The test was 100% specific when used for testing of 37 cervical specimens obtained after therapy of gonorrhea. The predictive values of a positive Gonozyme test were 90.5% for cervical specimens from women attending a sexually transmitted disease clinic and 97% for urethral specimens from men with urethritis. The predictive values of negative Gonozyme tests in these same circumstances were 100% for urethral specimens and 93.6% for cervical specimens.

Antigens, Bacterial↗