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Biomedical subjects

D Roy

Publications and source records attributed to D Roy.

At least 307 records · Page 17Linked to original sources
PubMed1986

Problems related to the detection of myocardial ischemia caused by coronary vasospasm.

We compared the sensitivity of three commonly used provocative tests, exercise, ergonovine and the cold pressor test, in a series of 34 hospitalized patients with well-documented, active variant angina. All tests were performed off medication at the same time of day, usually on 3 consecutive days. Angina was provoked by ergonovine in all 34 patients, by exercise in 17 and by the cold pressor test in only 5 (p less than 0.005). ST elevation developed during the ergonovine test in 32 (94%), during exercise in 10 (29%) and during the cold pressor test in only 3 (9%). With ergonovine one patient had ST depression only and one had no ECG changes. During the cold pressor test two patients had pseudonormalization of abnormally negative T waves and 29 had no ECG changes. Exercise induced T wave pseudonormalization in 4 patients, ST depression in 9 others and no ECG changes in 11. Thus, in patients with active variant angina, the sensitivity of the cold pressor test and exercise are too low to be useful clinically. Other studies suggest that the sensitivity of hyperventilation or provoked alkalosis is higher, but not as high as ergonovine administration. In patients who have become asymptomatic, either with treatment or spontaneously, the sensitivity of all tests decreases markedly. If such patients no longer have coronary spasm, the test is not a 'false negative' but a 'true negative'. Deaths have been reported following ergonovine administration and for this reason the test is not universally accepted.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

[Identification of the patient at risk for sudden death after infarction].

Considerable efforts have been made in the last few years to improve the diagnostic and treatment methods of arrhythmias following myocardia infarction. The recent progress in electrophysiology and in surgery have contributed to improve the prognosis of ventricular tachycardias, sustained and recurrent. On the contrary, the prognosis and therapeutic approach to "potentially malignant" but asymptomatic ventricular arrhythmias remain a subject of controversy and further study. The door remains open for the development of new techniques of detection and prevention of sudden death following myocardial infarction.

Death, Sudden↗
PubMed1985

Immunoreactive atrial natriuretic factor (IR-ANF) in human plasma.

A direct radioimmunoassay for ANF in human plasma was developed. A synthetic alpha-human atrial peptide (Ser 99-Tyr 126) was used for preparation of the iodinated tracer and the standards. The sensitivity of the method is 1.9 pg/ml. Concentration of immunoreactive ANF (IR-ANF) in plasma of 59 clinically normal subjects was 65.3 +/- 2.5 pg/ml (mean +/- SE). In two patients who underwent atrial pacing an increase of about 100 percent in circulating IR-ANF was observed. IR-ANF was extracted from human plasma by Vycor glass and purified by HPLC. The main immunoreactive isolated peak contained a low molecular weight peptide.

Atrial Natriuretic Factor↗
PubMed1985

The photolysis of lens fiber membranes.

Calf lens fiber membranes were photolyzed in the presence and absence of sensitizers and scavengers. Photolytic damage was assessed by SDS-polyacrylamide gel electrophoresis, UV and fluorescence spectra and amino acid analyses. With irradiation, there is an apparent polymerization of the major membrane polypeptide (MP26) and the formation of material which does not enter SDS-polyacrylamide gels. Some degradation was also observed. These changes are accompanied by losses of histidine and tryptophan and changes in the UV spectra. The rate of photolysis is enhanced in the presence of the glucoside of 3-hydroxykynurenine (3-OH-KYN), a compound endogenous to the lens. The reaction is retarded in the presence of sulfhydryl-containing compounds such as glutathione.

Amino Acids↗
PubMed1985

Comparison of clinical variables and variables derived from a limited predischarge exercise test as predictors of early and late mortality after myocardial infarction.

An exercise test limited to 5 METS or 70% of age-predicted maximal heart rate was performed 1 day before hospital discharge by 225 survivors of acute myocardial infarction, all of whom were subsequently followed up for at least 5 years. The mortality rate was 11.1% during the first year, but averaged only 2.9% per year from the second to fifth year. Over the entire follow-up period, the five variables that predicted mortality by multivariate analysis were QRS score, an exercise-induced ST segment shift, previous infarction, failure to achieve target heart rate or work load and ventricular arrhythmia during the exercise test. Because mortality differed markedly before and after 1 year, Cox regression analyses were performed separately for both of these periods. The factors that were predictive of mortality during the first year were an exercise-induced ST shift (p less than 0.0001, relative risk 7.8), failure to increase systolic blood pressure by 10 mm Hg or more during exercise (p = 0.0039, relative risk 4.3) and angina in hospital 48 hours or longer after admission (p = 0.0046, relative risk 3.4). None of these three variables was predictive of mortality after 1 year. Previous infarction (p = 0.0007), QRS score (p = 0.0042) and ventricular arrhythmia during the exercise test (p = 0.016) were predictive of mortality after the first year. Thus, clinical and exercise test variables are complementary predictors of mortality after myocardial infarction. An abnormal ST segment response during an early limited exercise test and angina in the hospital are common strong predictors of mortality to 1 year, but not thereafter. Late mortality correlates with markers of poor left ventricular function.

Adult↗
PubMed1985

Coronary angiographic significance of left anterior fascicular block during acute myocardial infarction.

The clinical and angiographic significance of isolated left anterior fascicular block occurring during the early stage of acute myocardial infarction was studied in 141 consecutive patients who underwent cardiac catheterization before hospital discharge. Left anterior fascicular block occurred in 15 of the 62 patients with an anterior wall infarction and in 13 of the 79 with an inferior infarction. None of the clinical characteristics differed among patients with or without left anterior fascicular block. The number of coronary vessels with significant stenosis, the Friesinger and the Gensini scores for severity of stenosis and the ejection fraction were also similar in the two groups. Patients with left anterior fascicular block had more severe narrowing of the coronary artery supplying the infarct zone (88 +/- 21 versus 70 +/- 35%, p less than 0.001) and tended to have less developed collateral circulation (collateral score 0.7 +/- 0.8 versus 1 +/- 0.8, p = 0.10). A significant stenosis of the left anterior descending coronary artery was found as frequently in patients with as in those without left anterior fascicular block (64 versus 65%); 29% of the patients with inferior wall infarction and left anterior fascicular block had left anterior descending coronary artery stenosis compared with 47% of the patients without this conduction disturbance (no significant difference). When the infarction was located anteriorly, a significant stenosis of the proximal segment of the left anterior descending coronary artery was present in 47% of the patients with and in 45% of the patients without left anterior fascicular block.(ABSTRACT TRUNCATED AT 250 WORDS)

Bundle-Branch Block↗
PubMed1985

Angiographic findings after myocardial infarction in patients with previous bypass surgery: explanations for smaller infarcts in this group compared with control patients.

The incidence of previous coronary artery bypass surgery (CABS) in patients with acute myocardial infarction admitted to our hospital has risen from 2.3% to 11.2% in 6 years. We compared infarct size and the angiographically determined cause of infarction in 52 control patients and in 52 consecutive patients with acute myocardial infarction at least 2 months after they had undergone CABS. Baseline characteristics were similar in both groups except for a higher incidence of preexisting Q waves in the post-CABS group (22 vs 10; p less than .05). Indexes of myocardial infarct size were smaller in the post-CABS group compared with those in control patients: peak creatine kinease (CK) level (IU/liter) 1113 +/- 1094 (mean +/- SD) vs 1824 +/- 1932 (p less than .01), peak CK-MB level (IU/liter) 173 +/- 230 vs 272 +/- 332 (p less than .02), peak summed ST segment elevation (mm) 3.5 +/- 4.8 vs 8.2 +/- 9.9 (p less than .005), and QRS score on days 7 to 10, 1.9 +/- 3.0 vs 4.3 +/- 3.4 (p less than .001). Postinfarction left ventricular ejection fraction was higher in the post-CABS group (53 +/- 13%) compared with that in control patients (47 +/- 12%; p less than .05). The incidence of total occlusion of the artery to the infarct zone was similar in the post-CABS and control patients (33 vs 27), as was the incidence of one-, two-, and three-vessel disease (artery plus graft). Collateral blood flow to the infarct zone was found in 27 post-CABS patients and in 23 control patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Programmed ventricular stimulation in survivors of an acute myocardial infarction.

The prognostic significance of programmed ventricular stimulation and its usefulness in relation to other forms of invasive and noninvasive testing was evaluated in 150 survivors of acute myocardial infarction. Ventricular tachyarrhythmias of 6 beats or more were induced in 35 (23%) patients. No significant differences existed between patients with inducible ventricular tachyarrhythmias and those without inducible ventricular tachycardia with respect to occurrence of spontaneous ventricular arrhythmias in the acute and early recovery phase of infarction or predischarge exercise-induced ischemia or arrhythmias, severity of coronary artery disease, or degree of left ventricular dysfunction. A higher incidence of inferior myocardial infarction was observed in patients with inducible ventricular tachycardia when compared with those without inducible ventricular tachycardia (66% vs 41%, p less than .01). During a mean follow-up of 10 +/- 5 months (range 2 to 19), there were two sudden deaths, three nonsudden deaths, and two additional patients developed sustained ventricular tachyarrhythmias. There was no significant difference between patients with and those without inducible ventricular tachyarrhythmias with respect to the occurrence of these events. In this study population, a lower mean ejection fraction (p less than .01), the presence of a ventricular aneurysm (p less than .05), and exercise-induced ventricular premature contractions (p less than .05) were predictors of sudden death and of spontaneous ventricular tachycardia. Thus, the findings of this study do not support the hypothesis that the induction of ventricular tachyarrhythmias in patients recovering from acute myocardial infarction identifies a group at high risk for sudden cardiac death.

Acute Disease↗
PubMed1985

The photosensitized oxidation of the calf lens main intrinsic protein (MP26) with hematoporphyrin.

Hematoporphyrin (HP), a drug used for the treatment of tumors including intraocular tumors, is an efficient photosensitizer. In addition to its therapeutic value, it also produces a phototoxic side effect in the skin. To test whether such effects may also occur in the eye, calf lens fiber membranes were photolyzed in the presence and absence of 1 mM HP. A marked increase (ca 5 times) in the photopolymerization of the calf lens membrane main intrinsic protein (MP26) was found in the presence of HP. Tenfold increases in destruction rates were found in losses of histidine. The MP26 was also photolyzed after tryptic and chymotryptic digestion to MP21, this resulted in an increased photopolymerization in the presence of 1 mM HP. These data suggest an age related increase in sensitivity of the lens fiber membrane proteins to such photoprocesses. The addition of both azide and penicillamine reduces the photosensitized loss of the main intrinsic protein.

Animals↗
PubMed1984

Occurrence of polyploidy and multinuclearity in the differentiating liver of chick embryo.

Increase in nuclear size in liver has been used as an index of polyploidy. It has long been considered that the occurrence of polyploidy and multinuclearity are characteristics of mammalian liver. The present study shows the occurrence of these phenomena in the liver of birds, so these features are not confined to mammals. 3 classes of nuclear size groups have been identified. The simultaneous occurrence of polyploidy and binuclearity indicates some sort of interrelationship between them.

Animals↗
PubMed1984

Does a booklet on breast self-examination improve subsequent detection rates?

Of 28 788 women aged 40 to 74 registered at 28 university teaching practices in greater Belfast, half were randomly selected to receive a booklet on breast self-examination from their general practitioner at the start of the study and 1 year later. The frequency of breast abnormalities was identical in both groups (0.83%) during the 2-year follow-up. Early malignant breast cancers (stages TX, TO, Tla) were significantly more frequent in the intervention group (53.6%) than in the control group (24.3%). Among women in the intervention group with malignant lesions, 2 sites, left nipple and left inner/upper quadrant, were significantly less frequently involved. These findings in relation to staging and site were confirmed by multivariate comparisons. The intervention group also had a smaller average tumour size (24.0 mm compared with 32.6 mm) due to significantly smaller benign tumours and the absence of the relationship between delay and tumour size evident in the control group.

Adult↗
PubMed1984

Nondisulfide polymerization of gamma- and beta-crystallins in the human lens.

The water-soluble 43,000-dalton fraction (WS43) of the human lens has been shown to be heterogeneous. It appears to contain, in addition to actin, components related to the crystallins. Immunoblot reactions indicate that this polypeptide fraction is composed of dimers containing beta- and gamma-crystallin components. It has been estimated that 10-30% of this fraction arises by dimerization of gamma-crystallin. A possible route for the formation of the 43,000-dalton fraction is suggested by the observation that photolysis of gamma-crystallin with light greater than 295 nm leads to polymer formation, including the 43,000-dalton fraction. The polymerization products react with anti-WS43. The results suggest that photochemical reactions may lead to the accumulation of polymers of some of the crystallins with aging of the human lens. Similar covalently linked polypeptides have previously been shown to be present in the high molecular weight aggregates associated with cataract formation.

Aging↗
PubMed1984

Effects of chlorpromazine on the activities of antioxidant enzymes and lipid peroxidation in the various regions of aging rat brain.

In this work, the effect of chronic intraperitoneal administration of chlorpromazine (5 and 10 mg/kg) on the antioxidant enzymes superoxide dismutase (SOD), catalase (CA), glutathione reductase (GR), and glutathione peroxidase (GP); lipid peroxidation; and lipofuscin accumulation in the brains of rats ages 6, 9, and 12 months was studied. Chlorpromazine increased the activities of SOD, GR, and GP in particulate fraction from cerebrum, cerebellum, and brain stem in a dose-dependent manner. While GR and SOD associated with soluble fraction increased, GP associated with soluble fraction was not affected. CA did not change after chlorpromazine administration in any regions of the brain of rats from all age groups. Chlorpromazine, thus, had a somewhat different action on antioxidant enzymes in different subcellular fractions. Chlorpromazine inhibited lipid peroxidation, both in vivo and in vitro, and it also inhibited accumulation of lipid peroxidation fluorescent products (lipofuscin), which was studied histochemically and biochemically as well. The data indicate that chlorpromazine inhibition of lipid peroxidation and of accumulation of lipofuscin can result from elevation of the activity of brain antioxidant enzymes.

Aging↗
PubMed1984

Dual atrio-ventricular nodal pathways and atrial fibrillation.

The determinants of the ventricular rate during atrial fibrillation were studied in a group of eleven patients demonstrating dual A-V nodal pathways during atrial stimulation. The shortest R-R interval and the mean ventricular cycle length during at least 1 min of pacing-induced atrial fibrillation were compared: a) to the effective and functional refractory period of the fast pathway; b) to the effective refractory period of the slow pathway determined during atrial stimulation, at two or more different basic cycle lengths of pacing; and c) to the shortest cycle length during atrial stimulation followed by 1:1 A-V conduction. A group of 8 patients not demonstrating dual A-V nodal pathway-curves during atrial stimulation was used as a control. In both groups the shortest R-R interval during atrial fibrillation was best predicted by the shortest cycle length followed by 1:1 A-V conduction during atrial stimulation. The mean ventricular cycle length during atrial fibrillation was not accurately predicted by any of the variables studied. The similar results in patients with and without dual A-V nodal pathways suggest that concealed conduction from one to another A-V nodal pathway does not play a role in determining the ventricular response during atrial fibrillation in patients with dual A-V nodal pathways.

Adolescent↗