PubMed Health⌕ Search

Biomedical subjects

J Warnock

Publications and source records attributed to J Warnock.

At least 19 recordsLinked to original sources
PubMed1998

The risk of missing angle neovascularization by omitting screening gonioscopy in acute central retinal vein occlusion.

OBJECTIVE: The purpose of the study was to determine whether angle neovascularization can occur without pupillary margin neovascularization in central retinal vein occlusion (CRVO). DESIGN: The study design was a prospective study of the main question and a retrospective study of ancillary issues. PARTICIPANTS: The authors examined 105 eyes of 100 patients with CRVO having clinical evidence of ischemia between July 1, 1986, and March 18, 1996. INTERVENTION: The authors looked for iris and angle neovascularization with both undilated slit-lamp biomicroscopy and Zeiss four-mirror gonioscopy. MAIN OUTCOME MEASURES: The presence of anterior segment neovascularization was measured. RESULTS: Of 34 eyes developing anterior segment neovascularization, 4 (12%) developed angle neovascularization without pupillary margin neovascularization over a mean follow-up of 2.2 +/- 2.4 standard deviation years. CONCLUSIONS: Angle neovascularization can occur without pupillary margin involvement in CRVO, implying the necessity of screening gonioscopy and supporting the Central Vein Occlusion Study conclusion (based on a photographic technique not used clinically).

Acute Disease↗
PubMed1995

Effects of pH on responses to adenosine, CGS 21680, carbachol and nitroprusside in the isolated perfused superior mesenteric arterial bed of the rat.

1. The receptors mediating the vasodilator responses to adenosine in the isolated mesenteric arterial bed of the rat were identified by use of selective agonists and antagonists and the involvement of the endothelium was examined. 2. Adenosine-mediated dilatation of the mesentery was potentiated by the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 100 microM), but in contrast, removal of the endothelium substantially reduced the responses to adenosine. 3. The order of potency of adenosine receptor agonists was: 5'-N-ethylcarboxamidoadenosine (NECA) > 2-p-(-2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS 21680) > 2-chloro-N6-cyclopentyl-adenosine (CCPA) > or = adenosine, suggesting the presence of A2A receptors. 4. Adenosine-mediated dilatation was inhibited by the non-selective adenosine receptor antagonist, 8-phenyltheophylline (3 microM) and by the A2A receptor antagonist 8-(3-chlorostyryl)caffeine (500 nM), but was unaffected by the A1 receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 10 nM). 5. Reducing the pH of the perfusate to 6.8 potentiated the actions of both CGS 21680 and adenosine, but the vasodilator effects of carbachol were the same at both pH values. The adenosine response at the lower pH as at pH 7.4, was unaffected by DPCPX. The actions of the nitrovasodilator, sodium nitroprusside, were also potentiated at pH 6.8 relative to those at the higher pH value but smaller responses were obtained at the lower pH value with forskolin, a stimulator of adenylyl cyclase, than at pH 7.4. 6. It is concluded that the adenosine receptor mediating dilatation of the rat mesenteric arterial bed is of the A2A subtype, that the response, under the conditions used, is apparently partly dependent on the endothelium (but not due to the release of nitric oxide), and that the response to activation of this receptor is potentiated by a reduction in pH which is similar to that seen in ischaemic conditions.

Adenosine↗