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Biomedical subjects

K Kaplan

Publications and source records attributed to K Kaplan.

At least 19 recordsLinked to original sources
PubMed1992

A novel regulatory myosin light chain gene distinguishes pre-B cell subsets and is IL-7 inducible.

We describe a novel regulatory myosin light chain gene (termed precursor lymphocyte-specific regulatory light chain or PLRLC) that is expressed specifically in precursor B and T lymphocytes. PLRLC is the first example of a regulatory myosin light chain gene which displays specific expression in non-muscle cells. PLRLC is expressed in adult bone marrow derived normal and transformed pre-B cells; in the former, PLRLC expression levels are induced by the pre-B cell specific growth factor interleukin-7 (IL-7). PLRLC is not expressed in either transformed pre-B cells derived from fetal liver or in normal fetal liver pre-B clones grown in the presence of IL-7. Therefore this gene provides the first marker that clearly distinguishes these two pre-B subsets. Finally, several of the different PLRLC transcripts potentially encode regulatory myosin light chains with unique structural features. The unique distribution, regulation and structural features of the PLRLC gene products suggest an important role for PLRLC during lymphocyte development.

Amino Acid Sequence↗
PubMed1990

Reduction of plasma cholesterol levels in normal men on an American Heart Association Step 1 diet or a Step 1 diet with added monounsaturated fat.

The design of diets to achieve optimal changes in plasma lipid levels is controversial. In a randomized, double-blind trial involving 36 healthy young men, we evaluated the effects on plasma lipid levels of both an American Heart Association Step 1 diet (in which 30 percent of the total calories were consumed as fat: 10 percent saturated, 10 percent monounsaturated, and 10 percent polyunsaturated fats, with 250 mg of cholesterol per day) and a monounsaturated fat-enriched Step 1 diet (with 38 percent of the calories consumed as fat: 10 percent saturated, 18 percent monounsaturated, and 10 percent polyunsaturated fats, with 250 mg of cholesterol per day). The effects of these diets were then compared with those of an average American diet, in which 38 percent of the total calories were consumed as fat: 18 percent saturated, 10 percent monounsaturated, and 10 percent polyunsaturated fats, with 500 mg of cholesterol per day. The men consumed the average American diet for 10 weeks before random assignment to one of the two Step 1 diets or to continuation of the average diet for an additional 10 weeks. Caloric intake was adjusted to maintain a constant body weight. As compared with the mean (+/- SD) change in the plasma total cholesterol level in the group that followed the average American diet throughout the study (-0.05 +/- 0.36 mmol per liter), there were statistically significant reductions (P less than 0.025) in the plasma total cholesterol level in the group on the Step 1 diet (-0.37 +/- 0.27 mmol per liter) and in the group on the monounsaturated fat-enriched Step 1 diet (-0.46 +/- 0.36 mmol per liter). There were parallel reductions in the plasma low-density lipoprotein cholesterol levels in these two groups. Neither the plasma triglyceride levels nor the high-density lipoprotein cholesterol concentrations changed significantly with any diet. We conclude that enrichment of the Step 1 diet with monounsaturated fat does not alter the beneficial effects of the Step 1 diet on plasma lipid concentrations.

Adult↗
PubMed1990

Skinfold thickness measurements in obese subjects.

To determine the accuracy of skinfold thickness measurements in body composition assessment, skinfold thicknesses, bioelectrical impedance, body density by underwater weighing, and total body water by deuterium dilution were determined in 105 healthy adults who varied widely in body fatness. Body fat ranged from 2.9% to 61.2% of body weight and a substantial number of obese subjects was included. The correlation between body fat calculated from skinfold equations and body fat measured by underwater weighing was in the same range as that between body fat estimated from impedance and underwater weighing. However, body fat calculated both from skinfold equations and bioelectrical impedance tended to be underestimated compared with body fat calculated from underwater weighing and total body water in the most obese subjects. In obese subjects it was not possible to measure significant numbers of skinfold thicknesses because of the inadequate size of the calipers.

Adult↗
PubMed1989

Effect of obesity on bioelectrical impedance.

The purpose of this study was to validate the use of bioelectrical impedance in assessing human body composition and to explore the use of this technique in obesity. Eighty-seven adults varying widely in body composition (range: 8.8-59.0% body fat) underwent measurement of bioelectrical impedance and underwater weighing (density). Fat-free mass determined from density (FFMd) was compared with FFM estimated from bioelectric impedance according to previously published regression equations. Correlation coefficients were high at all levels of body fat (0.94-0.99) but impedance equations overestimated FFM compared with FFMd in subjects greater than 42% body fat. This effect was greatest in subjects greater than 48% body fat and a regression equation was derived for determination of FFM for these subjects. These data confirm the excellent agreement between body composition determined from bioelectrical impedance and density but suggest that caution should be used in applying existing regression equations to very obese subjects.

Adult↗
PubMed1989

The influence of early surface thromboreactivity on long-term arterial graft patency.

The influence of early graft surface thromboreactivity on long-term arterial polyester (Dacron) graft patency was investigated with separate ex vivo and in vivo animal models. First, parallel, flow-regulated external aortocaval fistulae were created in five pigs with use of paired 8 mm X 35 cm crimped, warp-knitted, low-profile filamentous velour Dacron tubes: one tube preclotted with autologous blood, the other autoclaved after being soaked in human albumin. Autologous radiolabeled platelets, red cells, and radiolabeled human fibrinogen were injected at initiation of graft flow, with timed graft samples submitted for isotope gamma well-counting. Flow surface accumulation of radiolabeled blood elements was greater on the preclotted graft limb at-all time intervals studied, greatest after 5 minutes of flow initiation with RBC accumulation on the preclotted limb 5.19 +/- 0.84 (x +/- S.E.), platelet accumulation 5.57 +/- 1.00, and fibrinogen accumulation 1.82 +/- 0.14 times greater than that on the albumin-treated limb. Second, bilateral iliofemoral artery bypass grafts were placed in 12 mongrel dogs using 6 mm X 10 cm externally supported, noncrimped, warp-knitted, low-profile filamentous Dacron tubes. Before implant in each dog, one graft limb was clotted with autologous blood and the other was autoclaved after being soaked in 25% human albumin. Fresh autologous radiolabeled platelets were injected after wound closure in seven of these dogs. Postimplant graft imaging at 24 and 72 hours showed radiolabeled platelet accumulation to be 1.43 +/- 0.21 and 2.05 +/- 0.18 times greater on the preclotted graft limb. Six of 12 preclotted graft limbs and 7 of 12 albumin-treated graft limbs were patent when animals were killed 5 to 6 months after implant (not significant). Heat-denatured albumin-coated Dacron surfaces have a reduced early thromboreactivity but do not appear to greatly potentiate long-term arterial graft patency.

Albumins↗
PubMed1988

Efficacy of esmolol in the treatment and transfer of patients with supraventricular tachyarrhythmias to alternate oral antiarrhythmic agents.

The efficacy and safety of esmolol, a titratable intravenous beta-adrenergic blocking agent with a short elimination half-life (t 1/2 = 9.0 min) was evaluated in a multicenter open-label study for the treatment of supraventricular tachyarrhythmias (heart rate greater than 100 bpm). The study also investigated the feasibility of transferring patients from esmolol to alternate oral antiarrhythmic agents without loss of therapeutic response. Of the 113 patients studied, 95 (84%) achieved therapeutic response (reduction in heart rate of 15% or more or conversion to sinus rhythm). Most of these patients (93%) achieved the therapeutic response at esmolol doses of 200 micrograms/kg/min or lower. Transfer from esmolol to an oral antiarrhythmic agent(s) was studied in 76 patients. Alternate antiarrhythmic agents used in this study were digoxin (N = 25), propranolol (N = 21), verapamil (N = 10), metoprolol (N = 11), quinidine (N = 2), and a combination of two antiarrhythmic agents (N = 7). Sixty-seven (88%) patients were successfully transferred to oral antiarrhythmic agents without loss of the therapeutic response obtained with esmolol. The most frequent adverse effect observed during the study was hypotension, which resolved quickly (16 +/- 14 min) either by decreasing the dose or by discontinuation of esmolol infusion. This study supports previous observations concerning the safety and efficacy of esmolol in the treatment of supraventricular tachyarrhythmias. Furthermore, it demonstrates that the majority of patients successfully treated with esmolol can be safely and effectively transferred to oral therapy with alternate antiarrhythmic agents.

Adrenergic beta-Antagonists↗
PubMed1988

The effect of clonidine on the cessation of cigarette smoking.

The effect of clonidine on smoking cessation was studied by randomly assigning 186 smokers in a double-blind fashion to either placebo or clonidine. Abstinence from smoking was reported more frequently by subjects receiving clonidine, but the difference was statistically significant only at the end of the first week (34.4% vs 21.5%; p less than 0.05). Bothersome side effects were common and resulted in the early discontinuation of the study medication by 23 of the subjects taking clonidine and eight taking placebo (p less than 0.05). Although this study did not demonstrate a significant effect of clonidine on smoking cessation, a beneficial trend was detected and therefore further trials with transcutaneous delivery of this agent in combination with behavior modification techniques are warranted.

Adult↗
PubMed1988

The ultrasound appearance of radiation-induced hepatic injury. Correlation with computed tomography and magnetic resonance imaging.

The ultrasound findings in three cases of radiation-induced hepatic injury are described and compared with computed tomography and magnetic resonance imaging findings. Fatty infiltration of the liver was present in two of the cases in which concurrent chemotherapy was being administered. On ultrasound B-scans, the regions of radiation injury were hypoechoic relative to the remainder of the liver. This finding was more obvious in the patients with fatty livers. CT scans on the patients with fatty infiltrated livers showed higher attenuation in the irradiated region than in unexposed liver. In the patient where no fatty infiltration was present, the radiated section of liver had lower attenuation consistent with previous reports. Magnetic resonance imaging showed decreased signal in the exposed areas on T1 weighted images.

Child, Preschool↗
PubMed1987

Role of heparin after intravenous thrombolytic therapy for acute myocardial infarction.

The optimal approach to management of patients after thrombolytic therapy for acute myocardial infarction (AMI) is unclear. The role of anticoagulation with heparin was evaluated in 75 consecutive patients who received intravenous streptokinase for AMI. Heparin therapy was titrated to keep the partial thromboplastin time (PTT) between 90 and 120 seconds. Seventeen episodes of definite myocardial ischemia (associated with reversible electrocardiographic changes) were observed in 13 patients. When episodes of probable myocardial ischemia are included (typical chest pain relieved by nitroglycerin or associated with more than a 15-mm Hg change in blood pressure but without electrocardiographic changes), 52 episodes occurred in 28 patients. Four episodes of definite and 4 of probable myocardial ischemia occurred within 24 hours of discontinuation of heparin. Analysis of the level of anticoagulation as assessed by PTT at the time of the ischemic events shows that ischemia occurred more often at lower PTTs. Nine hemorrhagic complications occurred, all within 24 hours of streptokinase infusion. In 4 patients bleeding was believed to be major and heparin administration was discontinued; 2 patients with gastrointestinal bleeding required blood transfusions. Our data suggest that after thrombolytic therapy for AMI, the level of anticoagulation is inversely related to the frequency of recurrent ischemic events; that discontinuation of heparin is frequently associated with ischemia; and that administration of heparin is associated with a low incidence of hemorrhagic complications.

Female↗
PubMed1987

Hemodynamic and echocardiographic evaluation of the stumptailed macaque: a potential nonhuman primate model for pulmonary vascular disease.

Stumptailed macaques (Macaca arctoides) were evaluated as to their suitability as an animal model for pulmonary hypertension. Animals used for this study were colony-bred. Necropsy material from 63 animals revealed 32% with severe medial thickening of pulmonary arteries. Twenty-nine stumptailed macaques underwent cardiac catheterization and M-mode echocardiography. Hemodynamic measurement including pulmonary artery pressure response to 12% oxygen exposure identified three groups of animals with elevated, normal, and intermediate pulmonary artery pressures. Stumptailed macaques with elevated pulmonary artery pressure could be distinguished from other animals by echocardiography.

Animals↗
PubMed1986

Abnormal thallium 201 scintigraphy during low-dose vasopressin infusions.

Thallium 201 (201Tl) myocardial scans were obtained in 16 patients just prior to the discontinuation of a vasopressin infusion (.1 to .2 units/min) administered for the treatment of upper gastrointestinal bleeding. Repeat scintigraphy was performed two to three hours after the vasopressin was stopped. Eleven of the 16 patients (69 percent) demonstrated areas of decreased myocardial 201Tl uptake that resolved after the infusion was stopped. Heart rate-blood pressure product was significantly lower at the time of the second scan. Autopsies were secured in three of 11 scan-positive patients: one had severe coronary artery obstruction, one nonsignificant disease, and another had normal coronary arteries. Vasopressin, even at low doses, can induce abnormalities in myocardial perfusion that are probably mediated by a direct effect on the coronary circulation. They are usually not detectable by routine monitoring techniques and conceivably form the basis for the cardiovascular morbidity associated with the use of this agent.

Adult↗
PubMed1986

Prophylactic anticoagulation following acute myocardial infarction.

Although several large trials have failed to demonstrate unequivocally that anticoagulation decreases mortality following myocardial infarction (MI), anticoagulation has been advocated to prevent embolic cerebrovascular accidents (CVAs). Since CVAs occur during hospitalization in only 1.5% to 3% of MIs, it is not justifiable to anticoagulate all patients after MI because the risk of anticoagulation exceeds the potential benefit. However, a group of patients who are at high risk of developing left ventricular thrombi (LVT) and CVA following MI can be identified. Thirty percent to 40% of patients with transmural anterior MI develop LVT, and early anticoagulation with heparin sodium prevents LVT formation and CVAs in this group. A two-dimensional echocardiogram before hospital discharge allows the identification of patients at risk for later embolization and helps determine the need for anticoagulation with warfarin sodium following hospitalization.

Cardiovascular Diseases↗
PubMed1985

Frequency of pericardial effusion as determined by M-mode echocardiography in acute myocardial infarction.

A pericardial friction rub occurs in 6 to 16% of patients after acute myocardial infarction (AMI), but the incidence of pericardial effusion (PE) is not known. M-mode echocardiography was done 1, 3 and 5 days after AMI in 43 consecutive patients admitted within 24 hours of AMI, and PE was detected in 16 (37%). The PE was small in 7 patients, moderate in 6 and large in 3. A pericardial friction rub developed in 8 (19%), of whom only 4 had PE. Pleuritic chest pain diminished by sitting up and relieved by antiinflammatory agents developed in 12 (28%), of whom only 5 had PE. The peak creatine kinase level was significantly higher in patients with PE (1,769 +/- 1,003 U) than in those without (1,181 +/- 838 units). More patients with PE were in Killip classification II, III or IV (11 of 16 [69%] vs 9 of 27 [33%]). The presence of PE was not associated with age, site of AMI, development of Q waves, use of heparin or previous AMI. In conclusion, PE as detected by M-mode echocardiography is frequently present after AMI, and its presence is not closely associated with the occurrence of a pericardial friction rub or typical pericardial pain.

Aged↗
PubMed1985

Prophylaxis of supraventricular tachyarrhythmia after coronary bypass surgery with oral verapamil: a randomized, double-blind trial.

This study investigated the efficacy of oral administration of verapamil, started 24 hours after coronary artery bypass grafting (CABG), in reducing the incidence of postoperative supraventricular tachyarrhythmia (SVT). Two hundred patients were randomly assigned in a double-blind fashion to receive a one-week course of either a placebo or 80 mg of verapamil every 6 hours. Overall, SVT developed in 23 control and 14 verapamil-treated patients, a 39% reduction in incidence (p less than 0.10). Of the patients who received at least four doses and continued to receive the study drug, 17 in the control and 7 in the verapamil group experienced SVT, a 53% decrease in incidence (p less than 0.06). Atrial fibrillation constituted 34 of the 37 SVT episodes and was associated with a slower ventricular response in the group given verapamil (115 +/- 8 versus 156 +/- 4 beats per minute; p less than 0.001). No evidence was found linking postoperative SVT with the withdrawal of beta-blocking drugs. Adverse effects required that 20 patients in the verapamil and 6 in the placebo group be removed from the study. Hypotension or pulmonary edema or both developed in 13 of the patients receiving verapamil, but in only 1 of the control patients (p less than 0.001). We conclude that although verapamil has potential merit for the prophylaxis of SVT after CABG, its use in this setting is associated with a high incidence of unacceptable hemodynamic side effects.

Administration, Oral↗
PubMed1985

Myocardial necrosis in a patient with mixed connective tissue disease.

A 23-year-old black woman with mixed connective tissue disease developed acute onset of shortness of breath and evidence of pulmonary edema. Cardiac isoenzymes, electrocardiograms and radionuclide myocardial scintigraphy were consistent with focal myocardial necrosis. The patient has had no further myocardial complication since initiation of therapy with steroids.

Adult↗
PubMed1985

Brain abscess.

The results of CT brain scan in diagnosing and monitoring the course of brain abscesses and the recognition of the major role that anaerobic bacteria play in causing this disease have led to a reduction in disease mortality and have allowed a greater percentage of infected patients to recover without major neurosurgical procedures. Monitoring intracranial pressure, the availability of new antibiotics, and recognition and treatment of some of the more unusual syndromes associated with defective or suppressed immune systems have helped lead to a reduction in disease mortality from about 50 per cent to 10 per cent with excellent functional recovery in the majority of the patients.

Anti-Bacterial Agents↗