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Biomedical subjects

A Pines

Publications and source records attributed to A Pines.

At least 19 recordsLinked to original sources
PubMed1992

Usefulness of heavy isometric exercise echocardiography for assessing left ventricular wall motion patterns late (> or = 6 months) after acute myocardial infarction.

The aim of this prospective study was to determine the effects of heavy isometric exercise on left ventricular (LV) wall motion patterns in patients who have had myocardial infarction, and to compare heavy isometric exercise with dynamic exercise for competence in eliciting LV wall motion abnormalities at equivalent rate-pressure products. Echocardiography was performed in 42 patients during supine bicycle ergometry and during heavy dynamometer stretching at 50% of maximal voluntary contraction. Systemic vascular resistance increased from 1,484 to 1,649 dynes s cm-5 (p < 0.05) during isometric exercise, and decreased significantly during dynamic exercise. Wall motion abnormalities or new asynergy were induced by isometric exercise in 120 segments, 107 of which (89%) showed significant stenosis of the perfusing coronary artery. Hypokinesia was the dominant pattern in the range of 76 to 90% narrowing; akinesia was dominant at 91 to 100% narrowing. Wall motion abnormalities were also documented in 13 segments (11%) assumed to be supplied by vessels with nonsignificant stenosis. Dyskinesia, seen in 7% of the segments, was equally distributed between both groups with significant stenosis. Sensitivity and positive predictive value in identifying specific coronary vessel disease was similar for both isometric and dynamic exercise. In conclusion, heavy isometric exercise in patients who have had myocardial infarction induces wall motion abnormalities of a severity proportional to the degree of coronary narrowing. This exercise method is similar to dynamic exercise for ability in identifying obstructions in a specific vessel. Furthermore, when compared at near-equal rate-pressure products, heavy isometric exercise is far superior in sensitivity to dynamic exercise.

Adult↗
PubMed1992

Quantification of the disorder in network-modified silicate glasses.

Local order in silicate glasses has been observed by many experimental techniques to be similar to that in crystalline materials. Details of the intermediate-range order are more elusive, but essential for understanding the lack of long-range symmetry in glasses and the effect of composition on glass structure. Two-dimensional 17O dynamic-angle-spinning nuclear magnetic resonance experiments reveal intermediate-range order in the distribution of inter-tetrahedral (Si-O-Si) bond angles and a high degree of order in the disposition of oxygen atoms around the network-modifying cations.

Glass↗
PubMed1992

Sidebands in dynamic angle spinning (DAS) and double rotation (DOR) NMR.

A theory of dynamic angle spinning (DAS) and double rotation (DOR) NMR is described using average Hamiltonian and irreducible tensor methods. Sideband intensities in DAS and DOR spectra are analyzed by both the moment and Bessel function methods, and general formulae are derived. Results show that the DAS moments depend on the relative rotor phase between the first and the second evolution periods, whereas the second and third DOR moments are independent of the relative phase between the inner and outer rotors. Sideband intensities in DAS spectra also depend on the relative rotor phases between evolution at the first and second angles, as well as on the ratio of time spent at each angle. Sideband intensities and phases in DOR spectra are related to the relative rotor phases between the inner and outer rotors, and the sideband pattern is determined by the ratio of the inner and outer rotor spinning speeds. An inversion symmetry of the odd numbered DOR sidebands at the relative rotor phase gamma r = 0 degree, 180 degrees permits the elimination of these sidebands. Finally, numerical simulations are implemented and shown to agree with experimental results. Quadrupolar parameters can therefore be recovered either by calculating the second and third moments or by simulating the sideband intensities and phases.

Magnetic Resonance Spectroscopy↗
PubMed1992

Solid-state 27Al NMR studies of aluminophosphate molecular sieves. Enhanced resolution by quadrupole nutation and double-rotation.

Solid-state 27Al NMR spectra of several aluminophosphate molecular sieves have been recorded with conventional magic-angle spinning (MAS), double-rotation (DOR) and quadrupole nutation with fast MAS. Enhanced resolution was obtained in the quadrupole nutation experiment at certain radiofrequency pulse strengths. This extra resolution can be comparable to that attainable using DOR, and does not introduce spinning sidebands.

Aluminum↗
PubMed1992

Are tiny polyps important when found on sigmoidoscopy in asymptomatic people?

To determine the occurrence of synchronous large bowel polyps located proximal to the sigmoid, in persons undergoing screening flexible sigmoidoscopy, we examined those who had diminutive polyps (less than or equal to 0.5 cm) as the only finding in the distal colon by further colonoscopy. One hundred one asymptomatic persons (mean age 61 +/- 13 years) had 143 diminutive polyps; a single polyp was found in 76%, and 64% of all polyps were located in the rectum. Thirty (21%) were hyperplastic and 86 (60%) were neoplastic, including 14 with moderate and one with severe dysplasia. The others were inflammatory (five) or unclassified (hot biopsy changes or normal mucosa, 14 polyps), and eight were lost before processing. Colonoscopy revealed that 16 (16%) of the 101 patients had 21 additional polyps proximally, mostly less than 1 cm in diameter. These included one hyperplastic and 18 neoplastic polyps, and two specimens showed hot biopsy changes. Age, histological type, number or location of the index diminutive polyps, were not associated with proximal lesions. We question whether immediate colonoscopy is justified in asymptomatic patients with only diminutive polyps at flexible sigmoidoscopy.

Adult↗
PubMed1992

Neurocirculatory asthenia revisited: elevated arterial pressure at presentation is a marker for subsequent hypertension.

Neurocirculatory asthenia (NCA) is a fairly common functional disorder often encountered among military recruits. Symptoms in NCA tend to appear in waves, and are believed to disappear completely with the passage of time. Elevated arterial pressure is known to occur as part of the various haemodynamic manifestations of NCA. However, the exact prevalence of hypertension, as well as its long-term prognosis, is still unknown. The present case-control study was designed to address these two issues. The target population consisted of 370 patients with NCA representing two separate cohorts: patients diagnosed in 1979, 10 years prior to this study, and patients diagnosed in 1983-84, 5 years prior to the study. An overall 20% prevalence rate of mild hypertension at diagnosis was calculated for the entire study population. In total, 100 patients representing equal numbers of hypertensive and matched normotensive subjects from each cohort were re-evaluated. At follow-up, hypertension was present in 27% (1979 cohort) and 30% (1983-84 cohort) of patients originally considered to be hypertensive. Hypertension was either non-existent (1979 cohort) or limited to a single case (1983-84 cohort) among originally normotensive individuals. In parallel, resting heart rate was higher in the hypertensive subjects of the 1979 cohort both at presentation (85.5 +/- 3.2 vs. 73.7 +/- 2.4 beats min-1; P less than 0.005) and at follow-up (79.6 +/- 3.2 vs. 70.0 +/- 2.5 beats min-1; P less than 0.01). These results indicate that hypertension complicates the diagnosis of NCA in 20% of patients and that, contrary to common belief, it cannot be regarded as another transient manifestation of this condition. Thus hypertension in this context is, as in the younger members of the population in general, a major risk factor for lifelong hypertension, rather than an inconsequential phenomenon.

Adolescent↗
PubMed1992

Disseminated intravascular coagulation with renal and liver damage as the predominant manifestations of recurrent relapses in systemic juvenile rheumatoid arthritis.

Relapses of systemic juvenile rheumatoid arthritis associated with intravascular coagulation are rare. This paper describes a patient who, over a two year period, had two relapses, each accompanied by evidence of liver and renal damage and disseminated intravascular coagulation. The patient was not receiving non-steroidal anti-inflammatory drugs, and all laboratory and clinical manifestations of her disease rapidly resolved after treatment with prednisone. It is therefore believed that the hepatocellular damage, in addition to the disseminated intravascular coagulation, was a direct manifestation of disease activity. A possible pathogenic role for tumour necrosis factor is suggested.

Adult↗
PubMed1992

Colonoscopy in patients aged 80 years or older and its contribution to the evaluation of rectal bleeding.

Colonoscopies performed in patients aged 80 years or older at the Sheba Medical Center were analysed according to the primary indication for the procedure: 101 colonoscopies were performed because of rectal bleeding of at least 2 months duration, and 335 for all other indications. Carcinoma of the large bowel was found in 29 (28.7%) bleeders, with the rectum being the most frequently involved site (12 patients). Among the non-bleeders, the prevalence of cancer was significantly lower (33 cases, 9.8%; P less than 0.001), and rectal carcinoma was less common (five patients, P = 0.04), but proximal tumours were more frequent. Of patients with cancer who had operations, the majority (72%) had a tumour confined to the bowel wall (Dukes A or B). The rate of adenomas was similar for both groups (34% vs 29%). The non-bleeders complained more frequently of abdominal pain or a change in bowel habits as compared to the bleeders, but both groups had similar rates for anaemia and weight loss. In all, 47% of these octogenarians with cancer, and 26% with adenomas were referred for colonoscopy because of rectal bleeding. This procedure was found to be safe in old age, as we recorded only four (0.9%) non-fatal complications among our series, a similar figure to the overall incidence of complications at our Institute. In conclusion, our data indicate that rectal bleeding in octogenarians warrants a complete colonic investigation, preferably by total colonoscopy.

Aged↗
PubMed1992

Menopause-related changes in left ventricular function in healthy women.

Using technetium scans, this study was aimed at examining possible changes in left ventricular function related to the natural process of cessation of ovarian estrogen production. Fourteen healthy postmenopausal women, divided into two groups according to the time-lapse from menopause (A > 3 years; B < 5 years), underwent a technetium heart scan. The two groups did not differ in heart rate, blood pressure, double product, systemic vascular resistance and cardiac index. The mean end-systolic volume in group A was 14.9 and 25.7 ml/m2 in group B (p = 0.003). The mean pressure/volume ratio was significantly higher in group A than in group B (8.6 vs. 4.7 mm Hg/ml/m2, p = 0.02). Peak ejection rate and peak filling rate were also significantly greater in group A compared to group B (3.3 vs. 2.8 end-diastolic volumes/s, p = 0.02; 2.8 vs. 2.1 end-diastolic volumes/s, p = 0.001, respectively). Our findings suggest that women at an early phase of menopause have a higher degree of myocardial contractility than women of a similar age whose menopause is of longer duration.

Female↗
PubMed1992

Influence of ocular tropicamide on exercise testing.

This study was aimed to evaluate the effects of tropicamide 0.5% eye drops on cardiovascular parameters during exercise testing. The study group included 154 healthy subjects (mean age: 44.7 +/- 8 years). The subjects were divided into three groups according to the size of the pupils at the onset of exercise: A: pupils not dilated (n = 27), B: pupils partially dilated (n = 90) and C: pupils widely dilated (n = 37). They were compared to 66 healthy controls (age 43.8 +/- 8) who did not receive the drops. Rest and exercise parameters were affected in groups A and B, while the results of group C resembled those of the controls: (a) resting heart rate -66.7, 66.6, 70.9 and 69.3, respectively (p = 0.03); (b) heart rate at 50 and 100 W - 104, 107, 110 and 111 (p = 0.01) and 131, 131, 137, 139, respectively (p = 0.01); and (c) peak systolic blood pressure - 192, 186, 183, 175; respectively (p = 0.004). Reanalyzing the data by scoring of visual impairment gave identical results. As a whole, the study group achieved higher work loads than the controls (126 vs. 119 W; p = 0.03). We conclude that the instillation of ocular tropicamide has definite effects on cardiovascular parameters, both at rest and during exercise. Mainly, patients showed a lower heart rate at the initial levels of exercise. However, at symptom-limited level, tropicamide does not influence a patient's ability to achieve the target heart rate, and stress testing results are not altered by the drug.

Adult↗
PubMed1992

Combined effect of captopril and aspirin in renal hemodynamics in elderly patients with congestive heart failure.

Captopril and aspirin have been claimed to adversely affect renal function. This study was designed to evaluate the safety of concomitant administration of both drugs in patients with moderate to severe congestive heart failure (CHF). The study group consisted of 10 patients with a mean age of 77.6 +/- 4.4 years and a mean New York Heart Association functional class of 2.6 +/- 0.5. Captopril was administered in a rapidly escalating dose regimen over a 4-day period to a maximum dose of 75 mg/day. Aspirin 0.25 g/day was added from day 5 on. Renal plasma flow (RPF) was measured by iodohippurate scan and the creatinine clearance test (Ccr) was used as an index of glomerular filtration rate (GFR). Both Ccr and RPF remained unchanged throughout the study period; 48.9 +/- 16; 48.2 +/- 16.5; 49.4 +/- 16, and 222 +/- 67, 241 +/- 97, 237 +/- 88 ml/min, for days 0, 4, 9, respectively. Only 1 patient developed a significant decrease in Ccr following the administration of captopril. This patient had a further decrease when aspirin was added. The decrease in Ccr was accompanied by a marked reduction in filtration fraction and in mean arterial pressure. Our data suggest that the administration of aspirin to elderly patients with moderate CHF treated with captopril is relatively safe and is not associated with further deterioration in renal function.

Aged↗
PubMed1992

Erythropoietin therapy obviates the need for recurrent transfusions in a patient with severe hemolysis due to prosthetic valves.

Erythropoietin has been proved extremely effective in ameliorating the anemia of chronic renal failure and is currently under intensive investigation. We describe a patient with severe anemia and secondary hemochromatosis due to prosthetic valves, who has been successfully treated with erythropoietin. During 12 months' follow-up, an acceptable hemoglobin level was maintained without any need for blood transfusions; in addition, there was evidence indicating regression of hemochromatosis. This patient illustrates that erythropoietin therapy might prove beneficial for similar cases.

Anemia, Hemolytic↗
PubMed1992

Long-term effects of hormone replacement therapy on Doppler-derived parameters of aortic flow in postmenopausal women.

Eighteen postmenopausal women were examined by Doppler echocardiography before initiation of HRT (T1), then after ten weeks (T2) and one year (T3). This study group was compared with another in which HRT was not used. Flow velocity integral, which correlates with SV, and MA, an indicator of cardiac contractility, were calculated. In the study group, PFV was 107 +/- 18 cm/s at T1 and increased significantly at T2 and T3. Ejection time, which was prolonged at T2 compared to T1, returned to its basal value at T3. Flow velocity integral increased at T2, but this change was only partially sustained at T3. Mean acceleration maintained its increase throughout T2 to T3. None of the Doppler parameters showed a significant change in the controls from T1 to T3. Our results suggest that the peripheral hemodynamic effects of HRT, such as vasodilatation, are transient, whereas the central effects (increased inotropism) are long-lasting.

Aorta↗
PubMed1991

Sudden unexpected death in persons less than 40 years of age.

This study retrospectively assesses the underlying causes of sudden unexpected death and the occurrence of prodromal symptoms in 162 subjects (aged 9 to 39 years) over a 10-year period (1976 to 1985). Underlying cardiac diseases accounted for sudden death in 73% and noncardiac causes in 15% of subjects. In 12% of subjects, the causes were unidentifiable. Myocarditis (22%), hypertrophic cardiomyopathy (22%) and conduction system abnormalities (13%) were the major causes in 32 subjects aged less than 20 years. Major causes of 46 deaths in subjects 20 to 29 years were atherosclerotic coronary artery disease (24%), myocarditis (22%) and hypertrophic cardiomyopathy (13%). The largest number of deaths in 84 subjects aged greater than or equal to 30 years was attributed to coronary artery disease (58%), followed by myocarditis (11%). Among noncardiac causes of sudden death, intracranial hemorrhage was the most frequent (5%), followed by infectious disease (4%). Prodromal symptoms were reported by 54% of subjects; most frequent were chest pain (25%) in subjects aged greater than or equal to 20 years, and dizziness (16%) in those aged less than 20. Sudden death, which occurred during routine daily activity in 49% and during sleep in 23% of subjects, was related to physical exercise in 23% and emotional upset in 6%. Sudden unexpected death in the young is still an unresolved medical problem. The early recognition of prodromal symptoms could be crucial in the prevention of sudden death, specifically when exercise-related.

Adult↗