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Biomedical subjects

G Keren

Publications and source records attributed to G Keren.

At least 109 records · Page 6Linked to original sources
PubMed1989

Effect of isometric exercise on cardiac performance and mitral regurgitation in patients with severe congestive heart failure.

Left ventricular performance was studied during isometric exercise in 17 patients with severe congestive heart failure, combining invasive hemodynamic and echo-Doppler techniques. Isometric exercise at 30% of maximum resulted in a decrease in stroke volume index (27.4 +/- 7.1 to 22.7 +/- 7.4 ml/m2), with a significant increase in heart rate from 81 +/- 10 to 92 +/- 14 beats/min and in systemic vascular resistance from 1827 +/- 527 to 2372 +/- 737 dyne.sec.cm-5. A significant rise in pulmonary capillary wedge pressure (18 +/- 9 to 31 +/- 10 mm Hg) was associated with a marked increase in mitral regurgitant volume (14 +/- 11 to 27 +/- 15 ml), calculated as the difference between total stroke volume obtained by two-dimensional echocardiography and forward stroke volume measured by pulsed Doppler at the aortic anulus. During isometric exercise, left ventricular end-diastolic and end-systolic volumes did not change markedly, but the total stroke volume tended to increase from 62 +/- 13 to 67 +/- 13 ml. The increase in mitral regurgitant volume induced by isometric exercise was correlated with the fall in forward stroke volume (r = 0.7, p less than 0.01). Thus a rise in systemic arterial pressure induced by isometric exercise is associated with a decrease in cardiac performance attributable to redistribution of total left ventricular output with an increase in mitral regurgitation and a simultaneous decrease in forward cardiac output.

Aged↗
PubMed1989

Dynamics of functional mitral regurgitation during dobutamine therapy in patients with severe congestive heart failure: a Doppler echocardiographic study.

Functional mitral regurgitation plays a major role in determining the therapeutic response to vasodilators in patients with severe congestive heart failure. Its role in the response to inotropic therapy has not been studied in these patients. Ten patients with stage 3 or 4 congestive heart failure (New York Heart Association class) and secondary mitral regurgitation were studied before and during intravenous administration of dobutamine (mean dose, 7.4 microgram/kg/min). Hemodynamic measurements were obtained invasively. Echo and Doppler cardiography were used to determine cardiac volumes. Mitral regurgitation was calculated as the difference between total stroke volume by echo and forward stroke volume by Doppler. Mitral regurgitation area was calculated from a modified hemodynamic formula. Dobutamine caused a marked rise in mean forward stroke volume (43 to 61 ml), with a decrease in mitral regurgitation volume from 20 to 10 ml/beat and a drop in pulmonary capillary wedge pressure from 21 to 13 mm Hg. Since the pressure gradient between the left ventricle and atrium increased significantly during dobutamine therapy, only a marked decrease in the orifice of regurgitation could explain the changes in regurgitant volume. Indeed, the end-diastolic volume decreased from 254 to 234 ml and the orifice of mitral regurgitation was reduced from 0.25 to 0.12 cm2.

Aged↗
PubMed1989

The pharmacokinetics and therapeutic efficacy of fleroxacin and pefloxacin in a rat abscess model.

The penetration, pharmacokinetics and therapeutic efficacy of fleroxacin and pefloxacin were investigated in a rat abscess model. Abscesses were induced by implanting a dialysis tube unit contaminated with Serratia marcescens in the subcutaneous tissue. Simultaneous serum, interstitial fluid (IF) and abscess fluid concentrations of the investigated antibiotics were measured 24 and 96 h after implantation. The concentrations were determined at various time intervals after the last intramuscular administration of each drug (20 mg/kg). Peak fleroxacin and pefloxacin concentrations in the serum of the infected animals were 14.6 +/- 4.7 mg/l and 13 +/- 2.9 mg/l respectively, peak fleroxacin and pefloxacin abscess fluid concentrations after 24 h were 12.3 +/- 2.5 mg/l and 8.9 +/- 2.2 mg/l, respectively (85% and 68% of peak serum concentrations). Abscess fluid concentrations at 96 h were: fleroxacin 4.7 +/- 2.6 mg/l and pefloxacin 4.5 +/- 1.7 mg/l. Both antimicrobials persisted significantly longer in the abscess fluid than in serum. Both drugs failed to sterilize the abscesses following a single administration; however after four consecutive administrations all abscesses became sterile. We conclude that fleroxacin and pefloxacin may be suitable for the therapy of closed space infections caused by susceptible micro-organisms.

Abscess↗
PubMed1989

Dynamic mitral regurgitation. An important determinant of the hemodynamic response to load alterations and inotropic therapy in severe heart failure.

Cardiac performance and mitral regurgitation were measured by Doppler echocardiography and right heart catheterization in 12 patients with severe congestive heart failure who performed isometric exercise during control and intravenous administration of dobutamine and nitroglycerin. During control isometric exercise, mitral regurgitant volume increased from 18 +/- 13 to 31 +/- 17 ml (p less than 0.01), while forward stroke volume, by both thermodilution and Doppler echocardiography, substantially decreased. At rest, dobutamine decreased mitral regurgitant volume from 18 +/- 13 to 11 +/- 10 ml (p less than 0.05), while forward stroke volume increased from 46 +/- 13 to 55 +/- 15 ml (p less than 0.05). During isometric exercise, dobutamine tended to decrease mitral regurgitant volume (24 +/- 12 vs. 31 +/- 17 ml; NS) when compared with control exercise. At rest, nitroglycerin decreased mitral regurgitant volume from 18 +/- 13 to 11 +/- 11 ml (p less than 0.05), while forward stroke volume, by both thermodilution and Doppler echocardiography, substantially increased. Similarly, during isometric exercise, nitroglycerin decreased mitral regurgitant volume from 31 +/- 17 to 20 +/- 14 ml (p less than 0.05), while significantly increasing forward stroke volume. At control rest, the median mitral regurgitant fraction was 24% for the 12 patients. Neither dobutamine nor nitroglycerin changed significantly forward stroke and mitral regurgitant volumes at rest and during isometric exercise in the six patients with resting mitral regurgitant fraction below the median. In contrast, dobutamine and nitroglycerin significantly decreased mitral regurgitant volume and increased forward stroke volume both at rest and during isometric exercise in the six patients with mitral regurgitant fraction greater than the median.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Branhamella catarrhalis pneumonia in non-immunocompromised pediatric patients: report of three cases and review of the literature.

Branhamella catarrhalis (B.c.) is found as a commensal in the upper respiratory tract of a healthy individual. We report three pediatric patients with bronchopneumonia allegedly caused by B. catarrhalis. All of them were intubated and on a mechanical ventilation (following either elective surgery or trauma) while the infection developed. Although B. catarrhalis has been thought to be penicillin sensitive, an increased frequency of beta-lactamase producing B. catarrhalis has been noted recently. beta-lactamase positive B. catarrhalis is uniformly resistant to ampicillin and its susceptibility to the cephalosporins is quite variable. All the isolated strains were found susceptible to vancomycin. The three patients improved while being on therapy with vancomycin and peripheral airway cultures became sterile.

Adolescent↗
PubMed1988

Comparison of nalbuphine hydrochloride versus morphine sulfate for acute myocardial infarction with elevated pulmonary artery wedge pressure.

The hemodynamic and respiratory effects of intravenous nalbuphine hydrochloride and morphine sulfate were compared in a randomized fashion in 20 patients (age 65 +/- 11 years) with acute myocardial infarction and elevated pulmonary artery wedge pressure. Titration of the nalbuphine dose to lower pulmonary artery wedge pressure by greater than or equal to 25% resulted in a decrease of this parameter from 22 +/- 3 to 15 +/- 4 mm Hg, and was associated with a reduction in heart rate from 106 +/- 20 to 96 +/- 19 beats/min (p less than 0.05) and decreases in mean blood pressure (78 +/- 8 to 70 +/- 12 mm Hg, p less than 0.05) and mean pulmonary artery pressure (31 +/- 4 to 22 +/- 5 mm Hg, p less than 0.05), without any remarkable change seen in cardiac index (2.21 +/- 0.43 to 2.22 +/- 0.50 liter/min/m2, difference not significant), stroke volume index (22 +/- 7 to 23 +/- 4 ml/m2, difference not significant), stroke work index (17 +/- 7 to 18 +/- 7 g.m/m2), or systemic and pulmonary vascular resistances (1,675 +/- 333 to 1,513 +/- 508 and 191 +/- 78 to 170 +/- 109 dynes.s.cm-5 respectively, all differences not significant). Nalbuphine also significantly reduced respiratory rate (32 +/- 8 to 26 +/- 8 resp/min, p less than 0.05) and pH (7.45 +/- 0.04 to 7.41 +/- 0.03, p less than 0.05) and increased arterial PCO2 (32 +/- 6 to 35 +/- 6 mm Hg, p less than 0.05) without any major change in arterial PO2 (63 +/- 13 to 66 +/- 17 mm Hg, difference not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Failure of influenza vaccination in the aged.

A cohort of 127 nursing home residents aged 60-98 years were vaccinated during the winter of 1985-86 with the A-Chile 1/83 (C), A-Philippines 2/82 (P), and B-USSR (B) commercial influenza vaccines. Before vaccination 40%, 23%, and 69% were susceptible to influenza Ac, Ap, and B, respectively [hemagglutinin inhibition (H.I.) titer less than 1:40]. One month following initial vaccination, 32 patients [25%] remained unprotected against two or all three vaccine strains. These patients were revaccinated with the same influenza vaccine and followed up. At five months 11%, 19%, and 23% of the initial cohort were still unprotected against Ac, Ap, and B strains, respectively. We conclude that two conventional influenza vaccines administered one month apart leave unprotected 30% of healthy elderly people who are initial influenza vaccine failures.

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PubMed1988

Aplastic anaemia complicating adenovirus infection in DiGeorge syndrome.

An 18-month-old child with partial DiGeorge syndrome developed aplastic anaemia during an acute adenovirus infection. Assessment of the child's immune system revealed T-cell subset abnormalities consistent with DiGeorge syndrome. A possible link between the underlying immune deficiency and the observed complication is suggested.

Adenoviridae Infections↗
PubMed1988

CI-930, a new cardiotonic and vasodilating agent: hemodynamic comparison to dobutamine and long-term clinical effects.

The hemodynamic and clinical effects of parenteral and oral CI-930, a new phosphodiesterase type III inhibitor with combined vasodilator and inotropic properties, were studied in 12 patients with severe congestive heart failure refractory to therapy including captopril. The maximum response to dobutamine was also determined. Intravenous CI-930 increased cardiac index from 1.73 +/- 0.48 to 2.38 +/- 0.55 L/min/m2, and reduced pulmonary capillary wedge pressure from 19.2 +/- 7.9 to 12.5 +/- 6.4 mm Hg, mean right atrial pressure from 7.5 +/- 6.3 to 3.6 +/- 4.0 mm Hg, and systemic vascular resistance from 2288 +/- 860 to 1711 +/- 611 dynes . sec . cm-5 (p less than 0.001 for all). Heart rate and mean systemic arterial pressure were unchanged. The increment in cardiac index produced by dobutamine was higher than for CI-930, 2.68 +/- 0.55 vs 2.38 +/- 0.55 L/min/m2, p less than 0.001. However, reduction in pulmonary capillary wedge pressure tended to be less with dobutamine, 15.7 +/- 7.9 vs 12.5 +/- 6.4 mm Hg (NS). Hemodynamic benefits of oral CI-930 were equivalent to that of the parenteral drug. Duration of action was 9 to 12 hours. Chronic therapy resulted in subjective improvement in approximately 50% of patients. Exercise capacity, assessed by maximum oxygen consumption, was unchanged, 8.4 +/- 3.3 vs 9.8 +/- 3.4 ml/kg/min (NS). No overt laboratory manifestations of toxicity were observed.

Cardiotonic Agents↗
PubMed1988

Noninvasive quantification of mitral regurgitation in dilated cardiomyopathy: correlation of two Doppler echocardiographic methods.

The presence and severity of functional mitral regurgitation were quantified by Doppler echocardiography in 17 patients with dilated cardiomyopathy and no evidence of primary valvular disease. Mitral regurgitant fraction was greater than 20% in 11 of the 17 patients, and exceeded 40% in four patients. Total stroke volume, calculated from the difference between end-diastolic and end-systolic volumes obtained by two-dimensional echocardiography, correlated well with mitral valve inflow determined by Doppler echocardiography (r = 0.90, p less than 0.001). Similarly, mitral regurgitant volume, calculated as the difference between echocardiographic total stroke volume and forward aortic volume obtained by Doppler echocardiography, correlated well with regurgitant volume calculated as the difference between mitral valve inflow and forward aortic flow, both determined by Doppler echocardiography (r = 0.90, p less than 0.001). Accordingly, functional mitral regurgitation can be conveniently demonstrated in patients with dilated cardiomyopathy by two different Doppler echocardiography methods, whose results are closely correlated. Mitral regurgitant fraction is greater than 20% in two thirds of the patients with a dilated cardiomyopathy.

Aged↗
PubMed1988

Mitral anulus motion. Relation to pulmonary venous and transmitral flows in normal subjects and in patients with dilated cardiomyopathy.

The dynamics between mitral anulus motion, and, thus, motion of the base of the heart, and filling of the left atrium and ventricle were studied by Doppler echocardiography in 12 normal subjects and 28 patients with dilated cardiomyopathy. The normal motion of the mitral anulus is associated with two phases of inflow from the pulmonary veins. The first phase (J) of pulmonary venous inflow occurs during ventricular systole, concomitant with the descent of the mitral anulus toward the ventricular apex, the extent of which is 12.8 +/- 1.4 mm. The end of the descent of the anulus occurs at the cessation of aortic ejection. About 100 msec later, a rapid recoil of the mitral anulus toward the atrium coincides with the onset of transmitral filling. This rapid recoil contributes to the displacement of blood from the atria into the ventricles in early diastole. The second phase (K) of pulmonary venous flow begins in early diastole, with its peak occurring about 50 msec after the peak of transmitral flow. During atrial contraction, the mitral anulus moves slightly (2.4 +/- 0.7 mm) toward the atrium and then returns toward its initial position within 120 msec. This motion coincides with the A wave of transmitral flow. In patients with dilated cardiomyopathy, pulmonary venous flow and mitral anulus motion are markedly altered in comparison with normal subjects. In all patients, motion of the mitral anulus is either reduced or absent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Corynebacterium Group JK pathogen in cerebrospinal fluid shunt infection. Report of two cases.

The clinical and laboratory findings in two cases of aerobic Corynebacterium Group JK infection of cerebrospinal fluid (CSF) shunts are described. These organisms have occasionally been reported as a cause of serious infections in man but have not been reported as a cause of shunt infection. In both cases, CSF pleocytosis was limited to 20 or 60 cells with variable protein and sugar values. Fever was a constant finding, frequently accompanied by signs of central nervous system dysfunction. Corynebacterium Group JK organisms are common contaminants of the normal skin flora. When isolated from the blood and/or the CSF of a patient with a CSF shunt who has symptoms and signs compatible with infection, the organism should not be dismissed as a contaminant. A significant feature of this group is its resistance to almost all presently available antibiotics including penicillin, the cephalosporins, and the aminoglycosides. These organisms are, however, sensitive to vancomycin.

Cerebrospinal Fluid↗
PubMed1988

Severe congestive lupus cardiomyopathy complicated by an intracavitary thrombus: a clinical and echocardiographic followup.

Severe congestive cardiomyopathy is an uncommon complication of systemic lupus erythematosus (SLE). We describe a patient with active SLE and a circulating anticoagulant. She presented with a rapidly progressive cardiomyopathy, complicated by an intracavitary thrombus and cerebral infarction. The course of the disease is described, with special emphasis on the usefulness of consecutive echocardiographic studies.

Adolescent↗
PubMed1987

Bidirectional flow in congenital ventricular septal defect: a Doppler echocardiographic study.

The purpose of this study was to demonstrate the value of combined two-dimensional and pulsed Doppler echocardiography (echo) in localizing and recording bidirectional flow in congenital ventricular septal defect. Eight children, aged 8 months to 16 years, with clinical signs of a ventricular septal defect, underwent two-dimensional and pulsed Doppler echo study prior to cardiac catheterization. The ventricular septal defect was documented anatomically by two-dimensional echo in all eight patients. Flow patterns in systole and diastole through the ventricular septal defect and on both sides of the defect were carefully studied. In all eight children, systolic, high velocity, pathologic, left to right flow was documented when the sampling volume was positioned on the right ventricular side of the defect. When the sampling volume was positioned inside the defect, to and fro flow, left to right in systole and right to left in diastole, was observed. In children with moderate to large defects, the diastolic flow had a peak in early diastole. Increased pressure in the right ventricle over the left ventricle during the same period was demonstrated by cardiac catheterization and coincided with the Doppler flow. The direction of flow across the defect was affected by the size of the defect and the magnitude of the net shunt. Two-dimensional and pulsed echo Doppler were shown to be useful in demonstrating the ventricular septal defect and estimating its size and hemodynamic significance noninvasively.

Adolescent↗
PubMed1987

Right ventricular thrombus and pulmonary emboli in a patient with emphysema: an echocardiographic and Doppler documentation.

Pulmonary hypertension is a known complication of chronic obstructive pulmonary disease (COPD). A worsening dyspnea in a patient with COPD is usually a sequela of the pulmonary disease. However, it may be due to pulmonary embolism, a complication which is difficult to diagnose in such patients. We present a patient with COPD in whom two-dimensional and Doppler echocardiography confirmed the diagnosis of pulmonary emboli by documenting right ventricular thrombus and pulmonary hypertension. This case report emphasizes the usefulness of these noninvasive cardiac imaging techniques in the detection and evaluation of pulmonary embolism in patients with COPD.

Aged↗