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Biomedical subjects

A Hughes

Publications and source records attributed to A Hughes.

At least 163 records · Page 9Linked to original sources
PubMed1987

Endothelium-dependent relaxation in isolated human arteries and veins.

1. The role of the endothelium in mediating relaxation to acetylcholine, the calcium ionophore A23187, vasoactive intestinal peptide and peptide histidine methionine was studied using isolated human blood vessels. 2. Segments of renal, colic, pulmonary, uterine, transverse cervical, brachial, coronary and coeliac branch arteries, and saphenous veins, were obtained from surgical resection material for use in tissue bath studies. 3. Acetylcholine or A23187 produced endothelium-dependent relaxation in isolated vessels from all vascular beds studied. Coronary arteries, however, differed in their response to acetylcholine which produced predominantly a contractile response, either alone or after initial relaxation. 4. Vasoactive intestinal peptide and peptide histidine methionine produced endothelium-dependent relaxation in coeliac branch arteries. However, these peptides relaxed isolated pulmonary arteries independently of endothelium. 5. Endothelium-dependent relaxation in response to acetylcholine and A23187 was antagonized by nordihydroguaretic acid, a lipoxygenase inhibitor, and methylene blue and haemoglobin, inhibitors of soluble guanylate cyclase. In these respects the endothelium-dependent responses of human arteries to acetylcholine and A23187 resemble those described in other species.

Acetylcholine↗
PubMed1987

No evidence for a direct vasodilatory effect of celiprolol on human vasculature in vivo or in vitro.

Celiprolol is reported to be a new cardioselective beta blocker with novel ancillary properties including vasodilator effects. The purpose of this study was to investigate whether celiprolol possesses a direct vasodilatory effect on human vasculature in vivo and in vitro. We studied the in vivo effects of intra-arterial celiprolol (1-100 micrograms/min i.a.) on forearm blood flow (FBF). Forearm blood was measured by venous occlusion plethysmography. Possible vasorelaxant actions of celiprolol on human vascular smooth muscle were studied using segments of isolated human saphenous vein in vitro. The effect of celiprolol was investigated on resting tone or noradrenaline induced tone. Possible alpha 2-adrenoceptor antagonist effects of celiprolol were assessed using celiprolol as an antagonist of BHT933 induced constriction. Celiprolol was without significant effect on FBF and failed to relax isolated saphenous vein segments preconstricted with noradrenaline. The weak alpha 2-adrenoceptor antagonist action of celiprolol was demonstrable in human saphenous vein. This study does not provide evidence for a direct vasodilatory effect of celiprolol on human vasculature.

Adrenergic beta-Antagonists↗
PubMed1986

Optical image quality and the cone mosaic.

Contrary to the orthodox view that optical image quality should "match" the photoreceptor grain, anatomical data from the eyes of various animals suggest that the image quality is significantly superior to the potential resolution of the cone mosaic in most retinal regions. A new theory is presented to explain the existence of this relation and to better appreciate eye design. It predicts that photoreceptors are potentially visible through the natural optics.

Animals↗
PubMed1986

The action of a dopamine (DA1) receptor agonist, fenoldopam in human vasculature in vivo and in vitro.

This study was designed to investigate dopaminergic mechanisms in human vasculature using the selective vascular dopamine receptor agonist fenoldopam in vivo and in vitro. In vivo, forearm blood flow was measured plethysmographically and in vitro isolated rings of human blood vessels from a variety of sites were used for tissue bath studies. Intra-arterial fenoldopam markedly increased forearm blood flow, this effect was antagonised by (R) sulpiride, a vascular dopamine (DA1) antagonist, but not by metoclopramide, a neuronal (DA2) antagonist, or by guanethidine, an adrenergic neurone blocking agent. In vitro, fenoldopam relaxed preconstricted human renal, mesenteric and lumbar arteries, but not saphenous vein in a concentration dependent manner. (RS) sulpiride and SCH 23390 competitively antagonised this effect. These studies demonstrate the presence of a vasodilatory vascular dopamine receptor in man both in vivo and in vitro.

Adolescent↗
PubMed1986

Rapid Doppler screening test for internal carotid disease.

There is increasing evidence that only hemodynamically significant internal carotid lesions (of more than 50% diameter stenosis or occlusion) rather than minor lesions are the precursors of stroke. A Doppler test combining periorbital and direct audible interpretation of internal carotid Doppler signals was performed on 67 patients (134 internal carotids) and the results were compared with those from conventional biplane angiography. The test was 100% sensitive and had a positive predictive value of 91% for hemodynamically significant lesions. Negative predictive value for normal or less than 50% stenosis was 100%. Carotid bifurcation bruits were heard over only 25% of internal carotids with significant stenosis and nearly 60% of bruits were heard over internal carotids with minor disease. The equipment was portable and relatively inexpensive. The test could be performed by vascular technicians in less than 12 minutes with minimal patient discomfort, thus meeting most of the criteria for an ideal non-invasive screening test.

Adult↗
PubMed1986

Growth and acid production of Candida species in human saliva supplemented with glucose.

Growth characteristic and acid production of oral isolates of Candida albicans and Candida glabrata in glucose supplemented and glucose-free, pooled, human whole saliva were examined. Both Candida species exhibited sigmoidal growth curves in batch cultures of mixed saliva, supplemented with glucose. The growth of Candida in saliva was accompanied by a rapid decline in pH from 7.5 to 3.2 over 48 h and the major acidic components initiating and sustaining this pH drop were pyruvates and acetates. These acidic metabolites may play an important role in the pathogenesis of oral Candida infections.

Candida↗
PubMed1985

A model for p-aminobenzoic acid ester narcosis in goldfish.

A three-parameter equation which successfully quantifies the turnover time in goldfish exposed to variable concentrations of eight alkyl esters of p-aminobenzoic acid is described. One parameter characterizes the target concentration necessary to induce narcosis, and the other two parameters represent the resistances encountered by the drug when it migrates through aqueous and lipid phases from source to target. The octanol-water partition coefficients, or aqueous solubilities, and melting points of the esters are included to account for variation in drug hydrophobicity, the relationship between these properties being quantified. The inactivity of high-melting-point esters is explained by the constraint imposed by melting point on the maximum aqueous concentration which can be achieved by solid solutes.

4-Aminobenzoic Acid↗
PubMed1985

Chemotherapy with cyclophosphamide, adriamycin, and 5-fluorouracil compared to chemotherapy plus hormonal therapy with tamoxifen in the treatment of advanced breast cancer: an interim analysis.

Between February 1980 and August 1982, the Cancer and Leukemia Group B (CALGB) performed a randomized study aimed to compare chemotherapy with CAF (Cyclophosphamide, Adriamycin, 5-Fluorouracil) versus the same chemotherapeutic regimen plus tamoxifen (T-CAF) in stage IV breast cancer patients. Patients were stratified on the basis of menopausal status, estrogen receptors (ER) status, dominant site of metastasis and prior adjuvant treatment. Overall 474 patients were entered into the study of whom 433 were assessable for response. 314 patients were postmenopausal, 85 premenopausal and 34 patients were unknown as far menopausal status was concerned. No difference was evident among postmenopausal patients in overall response rate and duration of responses between T-CAF and CAF (52% vs 50% respectively). Similarly no difference was shown among premenopausal patients, response rates being 63% with T-CAF and 60% with CAF. Lack of benefit from adding T to chemotherapy was seen also according to the different strata, including patients with ER positive tumors. The failure for this combination to be synergistic might reflect an effect of T on tumor kinetics interfering with the activity of chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Irregularity and aliasing: solution?

Although irregularity in a sampling array reduces the Moire effects caused by undersampling, it makes interpolation more sensitive to noise. The advantages of irregularity are considered with this in mind.

Animals↗
PubMed1985

Effect of human colostrum and infant formula on the phagocytic activity of macrophages. I. Resident and stimulated mouse peritoneal macrophages.

Phagocytosis and degradation of radiolabelled human transferrin-anti-transferrin immune complexes by resident and stimulated mouse peritoneal macrophages was inhibited by liquid infant formula, particularly in the case of resident cells. Mouse peritoneal macrophages exposed to infant formula were shown by immunofluorescence to bind casein and beta-lactoglobulin, but there was little binding of alpha-lactalbumin. Comparison of various artificial milks, cow's milk and purified casein indicated that both the concentration and the degree of denaturation of casein may be important in the impairment of macrophage function by milk. It is suggested that bottle feeding of infants might result in impairment of macrophage function in the small intestine.

Animals↗