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M Rispoli

Publications and source records attributed to M Rispoli.

30 records · Page 2Linked to original sources
PubMed1985

Effects of histamine H1-receptor stimulation on coronary hemodynamics in man.

Exogenous histamine in man induces significant cardiovascular effects mediated by activation of H1 and H2-receptors present on human heart and on coronary arteries. We studied the effects of selective H1-receptor stimulation on human coronary hemodynamics in 10 patients undergoing cardiac catheterization. All patients were pretreated with cimetidine before the histamine infusion (0.5 micrograms/kg/min i.v. for 5 min). Six of these patients had normal coronary arteries and four had single vessel coronary artery disease (CAD) and vasospastic angina. During the study heart rate was held constant (100 beats/min) by coronary sinus pacing. We measured mean aortic pressure (MAP), coronary sinus blood flow (CSBF), coronary vascular resistance (CVR) and myocardial oxygen consumption (MVO2) at rest, during histamine infusion, and 10 min after the end of the infusion. During infusion, MAP decreased from 103 +/- 5 to 85 +/- 6 mmHg (p less than 0.02) and CVR from 1.00 +/- 0.16 to 0.81 +/- 0.14 mmHg/ml/min (p less than 0.05); CSBF and MVO2 did not significantly change. All parameters returned to baseline at the end of the infusion. The response was similar in patients with normal coronary arteries and in 3 patients with CAD. Only one patient with CAD developed angina with ST segment elevation in D3, reduction in CSBF and an increase in CVR. These results indicate that H1-receptor stimulation in man induces significant coronary dilatation and that histamine infusion after cimetidine pretreatment is unlikely to provoke coronary spasm in patients with vasospastic angina.

Adult↗
PubMed1977

Dissociation of lipolysis from the levels of cyclic AMP in rat epididymal fat cells.

Two compounds, theophylline and 8-aza-9-furfuryl-adenine (SQ 4665), were found to maximally stimulate lipolysis in preparations of rat epididymal fat cells in the absence of exogenous hormones. Cyclic AMP levels in lipocytes maximally stimulated by either agent alone were unchanged from control levels. In contrast, lipolysis stimulated by either epinephrine alone or in combination with several cyclic nucleotide phosphodiesterase inhibitors correlated well with increases in the levels of cyclic AMP observed. These results suggest the presence of a non-cyclic AMP dependent pathway for the stimulation of lipolysis in rat epididymal fat cells.

Adenine↗
PubMedDate not supplied

A possible role of chromatin and tightly-bound chromatin proteins on enzyme-catalyzed methylation of DNA.

Upon extensive digestion with DNAaseI of placenta chromatin matrix, previously "stripped" from its loosely-bound components by high-salt extraction, a fraction is obtained that contains almost no endogenous DNA methylase activity but whose DNA, if still included in this whole fraction--not if it has been purified to a protein-free condition--is a good substrate for externally added enzyme. This chromatin matrix can even cause a significant stimulation of methylation of single-stranded Micrococcus luteus DNA by placental methylase. In vivo, this phenomenon may have possible counterparts in the existence of highly-methylated regions of chromatin loops that appear to be protected by tightly-bound protein components from digestion of the "stripped loops" with DNAaseI.

5-Methylcytosine↗
PubMedDate not supplied

Direct coronary vasodilator effects of intracoronary histamine administration in humans.

Histamine is widely present in human tissues and can be released by immunologic and nonimmunologic reactions. Although several direct cardiovascular effects of histamine have been demonstrated in humans, little is known about the direct effects of histamine on the human coronary circulation in vivo. Therefore, we investigated the changes in coronary hemodynamics induced by bolus intracoronary administration of 4 micrograms of histamine to 11 patients with angiographically normal coronary arteries under continuous monitoring of R-R interval from the electrocardiogram, arterial pressure (AP), and coronary sinus blood flow (CBF), measured by thermodilution. Immediately after the end of the intracoronary histamine bolus, with R-R interval and AP unchanged, CBF increased from 144 +/- 20 to 238 +/- 27 ml/min (p less than 0.01) and coronary vascular resistance decreased from 0.7 +/- 0.16 to 0.42 +/- 0.1 mm Hg/ml/min (p less than 0.01). No change in coronary hemodynamics was observed after bolus intracoronary administration of physiologic saline. The effects of histamine on systemic hemodynamics consisted of a transient fall in AP and R-R interval, starting after the onset of changes in coronary hemodynamics. These data show that histamine possesses a direct coronary vasodilator effect in humans, independent of the determinants of myocardial oxygen consumption.

Adult↗
PubMedDate not supplied

Quality of vision: A consensus building initiative for a new ophthalmologic concept.

PURPOSE: Many studies have addressed the quantification of visual acuity, and the conventional method of measuring it has so far demonstrated serious limitations. Vision testing requires new methods that can more precisely express the quality of vision as perceived by the patient. METHODS: This study employed the Delphi method of consensus building. Concepts associated with quality of vision (QoV) were identified by a board of experts and proposed to participating specialists in two subsequent questionnaires. Upon receipt of the completed questionnaires, the replies were classified to determine the building blocks of a consensus. RESULTS: By analyzing the replies to the two questionnaires, the authors determined the key elements of QoV on which a consensus was found among the respondents. CONCLUSIONS: A consensus was reached on the opinion that the quantification of visual acuity by traditional means is inadequate for investigating QoV. Although visual acuity is still a basic element for testing, the experts believe that contrast sensitivity, reading speed, and microperimetry are additional parameters necessary for quantifying QoV. The use of a psychometric questionnaire on visual function could allow a better interpretation of visual impairment.

Consensus↗