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Biomedical subjects

J Coates

Publications and source records attributed to J Coates.

At least 55 records · Page 3Linked to original sources
PubMed1993

Functional characterization of three adenosine receptor types.

1. The purpose of the present study was to classify adenosine receptors into A1 and A2 subtypes in a wide range of isolated tissues and cell types (rat adipocytes and atria, guinea-pig ileum and atria (A1); guinea-pig aorta, dog coronary artery and human platelets and neutrophils (A2)) using the R- and S-diastereoisomers of N-phenylisopropyladenosine (PIA), N-cyclopentyladenosine (CPA), the novel compound, N-[(1S,trans)-2-hydroxycyclopentyl]adenosine (GR79236), N-[(2-methylphenyl)methyl]adenosine (metrifudil), 2-(phenylamino)adenosine (CV1808), and 2[[2-[4-(2-carboxyethyl)phenyl]ethyl]amino]-N- ethylcarboxamidoadenosine (CGS21680); N-ethylcarboxamidoadenosine (NECA) was used as a standard. 2. Results obtained in all tissue preparations previously reported to contain A1-receptors could be described by a single rank order of agonist potency: CPA > or = GR79236, R-PIA > or = NECA >> S-PAI > or = metrifudil > or = CV1808, CGS21680. 3. In contrast, two distinct rank orders of agonist potency were observed in preparations previously reported to contain A2-receptors. In dog coronary artery, human neutrophils and platelets the rank order of potency was: CV1808, CGS21680 > or = NECA > R-PIA > or = metrifudil > or = CPA > GR79236 S-PIA. However, in guinea-pig aorta the rank order was: NECA > metrifudil > R-PIA, CPA > CV1808, GR79236 > or = S-PIA, CGS21680. 4. The results of this study are consistent with the existence of three types of adenosine receptor: A1-and two subtypes of A2-receptor. The receptor present in dog coronary artery, human platelets and neutrophils, probably corresponds to the A2a subtype, whilst that present in the guinea-pig aorta may be of the A2b subtype.

Adenosine↗
PubMed1993

Characterization of the adenosine receptor mediating contraction in rat colonic muscularis mucosae.

1. The objective of this study was to characterize the adenosine receptor mediating contraction in rat isolated colonic muscularis mucosae (RCMM). 2. Sequential additions of the adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA; 0.01-10 microM) elicited reproducible, concentration-related contractions in RCMM. The effects of NECA were mimicked by the adenosine A1 receptor-selective agonists cyclopentyladenosine (CPA), R-phenylisopropyladenosine (R-PIA) and N-[1S, trans)2-hydroxycyclopentyl] adenosine (GR79236) and by S-PIA (the stereoisomer of R-PIA). The adenosine A2 agonists N-[(2-methylphenyl)methyl] adenosine (metrifudil) and 2-[p-(2-carboxyethyl)phenethylamine]-5'-N-ethylcarboxamidoadenosine (CGS21680) also produced contractions in RCMM but were 54 and 165 times less potent respectively than NECA. The rank order of agonist potency for contraction of RCMM was CPA > or = GR79236 = R-PIA > or = NECA > > S-PIA = metrifudil > CGS21680, which is identical to that reported for the inhibition of spontaneous rate in rat isolated right atria and inhibition of lipolysis in rat isolated adipocytes by these same agonists. 3. R-PIA, S-PIA and metrifudil behaved as partial agonists in RCMM. 4. The adenosine A1 receptor-selective antagonist 8-cyclopentyl-1,3- dipropylxanthine (DPCPX) inhibited the contractions produced by all the adenosine agonists tested, with pKB values between 9.2 and 9.5. The non-selective adenosine antagonist 8-phenyltheophylline (8-PT) antagonized the effects of NECA but also markedly potentiated (by 93.0 +/- 10.2% at 3 microM) the maximum contractile response to NECA in RCMM. Neither 8-PT (3 microM) nor DPCPX (0.1 microM) had any effect on the contractions produced by carbachol. 5. The contractile responses to NECA in RCMM were not affected by atropine (1 microM), tetrodotoxin(0.3 microM) or the P2 antagonist, suramin (100 microM).6. The present study confirms that contractions to adenosine agonists in the RCMM are mediated via adenosine Al receptors.

Adipocytes↗
PubMed1993

Adequacy of prescribing positive airway pressure therapy by mask for sleep apnea on the basis of a partial-night trial.

We tested the hypothesis that a prescription for positive-pressure therapy (including pressure level, patient-device interface, and positive-pressure modality, e.g., CPAP or BiPAP) for obstructive sleep apnea (OSA) can be developed on the same night as the polysomnographic (PSG) diagnosis is made. Fifty consecutive patients with OSA in whom a partial-night PSG diagnosis was made (PSGD) underwent a therapeutic trial of positive-pressure therapy during the remainder of the night (PSG-PPP). The average apnea index during PSGD was 54.96 +/- 36.3 (mean +/- SD). On a subsequent full-night PSG (PSG-PPF), the prescription was tested. Thirty-one of the 50 patients were satisfactorily treated with CPAP, without variation of the interface during both PSG-PPP and PSG-PPF. In these patients the average pressure prescription while receiving PSG-PPF was statistically higher than during PSG-PPP (11.77 +/- 3.6 versus 10.56 +/- 3.6 cm H2O, respectively, p = 0.002). In 14 of these 31 patients (45%) some alteration in pressure requirement was necessary during PSG-PPF. Eleven patients required 2.5 cm H2O higher pressure and three patients required 5 cm H2O higher pressure during PSG-PPF than during PSG-PPP. There was a change of interface across the two therapeutic trials in 15 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1993

A comparison of diagnosis related groups and ambulatory visit groups in day-case surgery.

Case-mix measurement is a basic requirement of clinical and resource management systems within health care organisations, and offers a potentially useful tool for the setting and monitoring of contracts. Ambulatory care has particular problems in the construction of appropriate case-mix measures, and day-case surgery provides an opportunity to test two existing measures, one inpatient (Diagnostic Related Groups) and one ambulatory (Ambulatory Visit Groups). These grouping systems were applies to the same data to compare the case-mix patterns that they produce. The findings show that the ambulatory visit group appear to have advantages over the diagnostic group with respect to their underlying assumptions and labelling of the groups; in particular, they assign greater weight to procedures. However, diagnostic groups are more developed, easier to use, more familiar and allow direct comparisons with inpatient care. Nevertheless, a proper evaluation of these issues requires further data collection and analysis, together with a fundamental examination of the uses of ambulatory case-mix.

Ambulatory Surgical Procedures↗
PubMed1993

A comparison of diagnosis related groups and ambulatory visit groups in day-case surgery.

Case-mix measurement is a basic requirement of clinical and resource management systems within health care organisations, and offers a potentially useful tool for the setting and monitoring of contracts. Ambulatory care has particular problems in the construction of appropriate case-mix measures, and day-case surgery provides an opportunity to test two existing measures, one inpatient (Diagnosis Related Groups) and one ambulatory (Ambulatory Visit Groups). These grouping systems were applied to the same data to compare the case-mix patterns that they produce. The findings show that Ambulatory Visit Groups appear to have advantages over the Diagnosis Related Groups with respect to their underlying assumptions and labelling of the groups; in particular, they assign greater weight to procedures. However, Diagnosis Related Groups are more developed, easier to use, more familiar and allow direct comparisons with inpatient care. Nevertheless, a proper evaluation of these issues requires further data collection and analysis, together with a fundamental examination of the uses of ambulatory case-mix.

Ambulatory Care↗
PubMed1992

Fasting in the rat does not induce hyperfibrinogenaemia.

The effects of fasting in the rat on the plasma fibrinogen concentration have been investigated. Fasting for 24-48 hr produced the expected sustained increase (4-5-fold) in the concentrations in the plasma of non-esterified fatty acids, but no accompanying increase in that of fibrinogen was detected.

Animals↗
PubMed1991

Alpha 2-adrenoceptor blocking profile of SK&F 104078: further evidence for receptor subtypes.

1. The ability of the putative, selective post-junctional alpha 2-adrenoceptor antagonist, SK&F 104078 to antagonize the effects of structurally-diverse agonists at pre-junctional alpha 2-adrenoceptors in the guinea-pig ileum and rat vas deferens in vitro and in the rat heart in vivo, and at post-junctional alpha 2-adrenoceptors in the rabbit ear vein in vitro, was examined. Results obtained with SK&F 104078 were compared with those obtained with yohimbine. 2. Xylazine and B-HT933 each caused a concentration-dependent inhibition of the field-stimulation-evoked twitch responses of the guinea-pig ileum and rat vas deferens. SK&F 104078 did not antagonize either agonist in the guinea-pig ileum and exerted only minimal blocking activity against xylazine in the rat vas deferens. In contrast, SK&F 104078 competitively antagonized B-HT933 in the rat vas deferens (pA2 = 6.45). Yohimbine competitively antagonized both agonists in each tissue (pA2 values ranged between 7.46 and 7.88). 3. In the pithed rat xylazine and B-HT933, injected intravenously, caused a dose-dependent reduction in the tachycardia elicited by stimulation of the cardiac preganglionic sympathetic nerves. SK&F 104078 (10 mg kg-1, i.v.) caused a 20-30 fold rightward displacement of the dose-response curve to xylazine, but did not affect responses to B-HT933. Yohimbine (1 mg kg-1, i.v.) antagonized both agonists to a similar degree. 4. In the rabbit ear vein xylazine, B-HT933, noradrenaline and UK 14304 elicted vasoconstrictor responses. Prazosin was without effect, but in contrast, SK&F 104078 was a competitive antagonist of each of the agonists (pA2 values ranged between 6.63 and 6.72). Yohimbine also competitively antagonized each of the agonists in this preparation (pA2 values ranged between 7.81 and 8.07). 5. SK&F 104078 was also a competitive antagonist (pA2 = 6.20) against noradrenaline at post-junctional alpha 1-adrenoceptors in the rabbit aorta. 6. These data show that SK&F 104078 is a competitive antagonist at post-junctional alpha l- and alpha 2-adrenoceptors. Its antagonist potency at pre-junctional alpha 2-adrenoceptors is agonist- and tissuedependent. Yohimbine does not discriminate between pre- and post-junctional alpha 2-adrenoceptors. The findings are discussed in terms of the possible existence of subclasses of OC2-adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed1991

Diagnosis of sleep-disordered breathing by half-night polysomnography.

We hypothesized that sleep-disordered breathing (SDB), defined by the apnea index (AI), the apnea + hypopnea index (A + H/I), or the desaturation event frequency (number of desaturations greater than 5%/h slept) (DEF), could be diagnosed after less than full-night polysomnography (PSG). Forty-eight consecutive full-night PSG sessions were evaluated by separately analyzing the first half (PSG-1/2) and the total (PSG-T) sleep time: 134.42 +/- 35.7 and 277.15 +/- 56.5 min (mean +/- SD), respectively. PSG-1/2 and PSG-T were not different with respect to AI. The DEF was statistically but not clinically higher during PSG-1/2 (41.72 +/- 41 versus 37.95 +/- 35.8, p = 0.04). Sensitivities, specificities, and predictive values of each PSG-1/2 parameter were determined by comparing the values with those measured during PSG-T, using cutoff frequencies of both 5 and 10 events/h slept to define SDB. At a cutoff frequency of 10, sensitivities and positive predictive values were high for all PSG-1/2 parameters (range, 94.6 to 96.9%). The specificities of the DEF and AI during PSG-1/2 were also high (93.75 and 95%, respectively), but the negative predictive value of the DEF was substantially better (93.75 versus 83.3%). With SDB defined by 5 events/h slept, there also were high sensitivities (87.9 to 93%), positive predictive values (93.6 to 100%), and specificities (86.7 to 100%) for all parameters. Negative predictive values, however, were substantially reduced (62.5 to 76.5%). We conclude that PSG during 2 h of sleep is an appropriate method for evaluating SDB.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗
PubMed1990

Lack of significant interaction between low dose methotrexate and ibuprofen or flurbiprofen in patients with arthritis.

Low dose methotrexate (MTX) is widely used in the treatment of rheumatoid arthritis. Current product recommendations accompanying MTX preparations advise against concurrent usage of nonsteroidal antiinflammatory drugs (NSAID), and adverse pharmacokinetic interactions have been reported with this combination. Six patients who were receiving MTX were studied with both oral and parenteral MTX, 10-25 mg/dose, without NSAID and with ibuprofen (2400 mg/day) and flurbiprofen (300 mg/day) for 6 weekly doses. Serum MTX levels were obtained at frequent intervals. Serum was separated and MTX analyzed using a radioimmunoassay (RIA). There was no observable interaction between MTX and either ibuprofen or flurbiprofen, with respect to the area under the curve per unit dose, Cmax, Cmax/dose, Tmax, and serum half-life. The pharmacokinetic indices were not significantly influenced by the route of administration.

Administration, Oral↗
PubMed1987

Cyclosporin-induced gingival overgrowth: correlation with dental plaque scores, gingivitis scores, and cyclosporin levels in serum and saliva.

Gingival overgrowth, dental plaque, and gingivitis were assessed by means of standardized semiquantitative indices in thirty renal transplant patients undergoing immunosuppression with cyclosporin-A (Cy-A). Radioimmunoassay techniques were used to determine Cy-A in serum samples and in parotid, submandibular, and whole saliva samples from each patient. A significant positive correlation was found between gingival overgrowth scores and both dental plaque and gingivitis scores. A significant positive correlation was found between whole-saliva Cy-A and both plaque and gingival overgrowth scores. No such correlation was found when parotid Cy-A or submandibular Cy-A was considered. This was attributed to differences in saliva-collection methods, and a possible role of dental plaque as a local reservoir of Cy-A is proposed.

Adult↗
PubMed1985

Measuring endogenous digoxin-like substance and exogenous digoxin in the serum of low-birth-weight infants.

The interference with three serum digoxin assay methods of endogenous digoxin-like substance (EDLS) in the serum of low-birth-weight (LBW) infants was assessed. The serum from 5-mL blood samples obtained from each of 19 LBW infants was divided into four 0.5-mL portions. Each portion was spiked with 10 microL of a distilled water-ethanol solution with or without digoxin to produce final digoxin concentrations of 0 (control), 0.49, 0.98, or 1.96 ng/mL. Each portion in each patient was then analyzed by radioimmunoassay (RIA), fluorescence polarization immunoassay (FPIA), and radial partition immunoassay (RPIA) using the control portions to measure EDLS. Serum digoxin concentrations measured by each assay method were calculated by subtracting the EDLS concentrations in the control portions from the measured digoxin concentrations in the spiked samples. The mean +/- S.D. concentrations of EDLS measured by RIA and FPIA were 0.26 +/- 0.13 ng/mL and 0.33 +/- 0.16 ng/mL, respectively. Of the 19 control samples assayed by RPIA, 18 had EDLS concentrations less than 0.1 ng/mL; one sample reflected an apparent concentration of 0.11 ng/mL. Mean recovered digoxin concentrations by RIA at each spiked digoxin concentration were significantly different from those obtained by FPIA and RPIA. A low but significant correlation was noted between EDLS concentrations in serum samples assayed by RIA and FPIA. The RPIA method appears to be preferred over the RIA and FPIA methods used in this study for serum digoxin analysis in LBW infants because of acceptable accuracy and minimal interference by EDLS.

Blood Proteins↗
PubMed1983

Occurrence of alpha 1s-adrenoceptors in the mouse but not in the rabbit isolated anococcygeus preparations.

1 Both Sgd 101/75 (4(2-imidazoline-amino-2-methylindazol-chlorhydrate) and noradrenaline contracted anococcygeal preparations from the mouse and rabbit. 2 The maximal response to and sensitivity (EC30 values) of each drug on the mouse was similar, whereas in the rabbit, Sgd 101/75 was a partial agonist relative to noradrenaline (intrinsic activity 0.50) and the EC30 value was 14.5 times higher than for noradrenaline. 3 In both species, phenoxybenzamine (0.3 nM for 30 min followed by 20 washes over 30 min) reduced the effects of Sgd 101/75 preferentially. When noradrenaline was then added in the presence of a high concentration of Sgd 101/75 (400 microM), its maximum response and EC30 value were decreased in the rabbit, but not in the mouse. 4 When a range of concentrations of phenoxybenzamine (30 pM-3 microM for 30 min followed by 20 washes over 30 min) was tested, the maximum response of the rabbit anococcygeus to noradrenaline declined in a concentration-dependent manner. Similar experiments in the mouse resulted in two distinct sensitivities of the maximum response of noradrenaline to phenoxybenzamine (at 0.3 and 300 nM). 5 The results indicate that noradrenaline acts on two receptors to contract the mouse anococcygeus (alpha 1 and alpha 1s-adrenoceptors), but only one (alpha 1-adrenoceptor) in preparations derived from the rabbit.

Adrenergic alpha-Agonists↗
PubMed1983

Demonstration of alpha 1s-adrenoceptors after exposure of the rat anococcygeus to benextramine.

Sgd 101/75 (4(2-imidazoline-amino)-2-methylindazol-chlorhydrate) and noradrenaline exerted similar, full agonist effects on the alpha-adrenoceptors of the rat anococcygeus. Benextramine (30 microM for 30 min, followed by 20 washes over 30 min) abolished contractions of the anococcygeus to Sgd 101/75, but only reduced those to noradrenaline. Sgd 101/75 (400 microM) did not significantly reduce contractions of the benextramine-treated (30 microM) anococcygeus to noradrenaline. It is concluded that benextramine can replace phenoxybenzamine as the alkylating agent in the demonstration of alpha 1s-adrenoceptors in the rat anococcygeus.

Adrenergic alpha-Antagonists↗