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Biomedical subjects

S Kaplan

Publications and source records attributed to S Kaplan.

At least 379 records · Page 21Linked to original sources
PubMed1982

Purification and characterization of an N-acylphosphatidylserine from Rhodopseudomonas sphaeroides.

A new phospholipid that can account for up to 40% of the total cellular phospholipid of Rhodopseudomonas sphaeroides has been identified. Purification of the phospholipid was accomplished by column chromatography on silicic acid and diethylaminoethylcellulose followed by preparative thin-layer chromatography. A combination of spectroscopic and chemical techniques were used to identify the unknown phospholipid as an N-acylphosphatidylserine. Infrared spectroscopy revealed the presence of both ester and amide bonds in the phospholipid. Interpretation of the proton nuclear magnetic resonance spectrum of the new phospholipid indicated the presence of three acyl chains per phospholipid and in all other respects was compatible with the proposed structure of the molecule. Chemical studies confirmed the presence of a glycerylphosphorylserine moiety in the molecule and yielded three fatty acyl chains per hydrolyzed phospholipid. The fatty acid composition of the phospholipid was approximately 85% vaccenic acid, 9% stearic acid, 5% palmitic acid, and 1% palmitoleic acid, which is essentially identical with the fatty acid composition of whole cell phospholipid preparations from R. sphaeroides. Chemical synthesis of an N-acylphosphatidylserine from beef brain phosphatidylserine and palmitic anhydride gave a product with characteristics similar to those of the naturally occurring material isolated from R. sphaeroides.

Chromatography, Thin Layer↗
PubMed1982

Radionuclide angiographic and echocardiographic quantitation of left-to-right shunts in children with ventricular septal defect.

Pulmonary to systemic blood flow ratios (Qp:Qs) were estimated in 16 children with ventricular septal defects using simultaneous echocardiography and radionuclide angiography, and compared to Qp:Qs measured at cardiac catheterization by the Fick principle method (Fick). When ratios of echographic left atrial dimensions (LAD) to body surface area (LAD/M2), body length (LAD/ht), and aortic root diameter (LAD/Ao) were compared to the Qp:Qs determined by Fick, the correlation coefficients were r = 0.70 for LAD/M2, r = 0.66 for LAD/ht, and r = 0.54 for LAD/Ao. The correlation coefficients between Qp:Qs by Fick, and left ventricular dimensions/M2 and fractional shortening of the left ventricle were not significant. The correlation coefficients between Qp:Qs and the ratios estimated by gamma-variate and area-ratio analysis of radioisotope pulmonary dilution curves were r = 0.92 and r = 0.84, respectively. Thus, radionuclide angiography provided more accurate quantitation of left to right shunting through a ventricular septal defect than echocardiography. However, difficulty in obtaining adequate bolus injections of the radioisotope may result in technical failures whereas echocardiographic measurement is possible in almost all pediatric patients. Finally, the gamma-variate method cannot accurately quantitate shunt ratios greater than 3.5 to 1.

Adolescent↗
PubMed1982

Postoperative evaluation of the Fontan procedure by radionuclide angiography.

Seven patients were evaluated by radionuclide angiography (RNA) following Fontan-like procedures for complex cyanotic congenital defects. Both first-pass and ECG gated equilibrium angiography were performed in each. Residual right-to-left shunts, right atrial (RA) outflow and pulmonary arterial obstruction, and left ventricular dysfunction were demonstrated by these techniques. In addition, RA ejection fraction (RAEF) by gated equilibrium scan was measured in each patient. Relatively low RAEF was seen in conjunction with residual obstruction to pulmonary flow. RNA is useful in the postoperative evaluation of patients after Fontan procedures.

Adolescent↗
PubMed1982

Primary benign intramural ventricular tumors in children: pre- and postoperative electrocardiographic, echocardiographic, and angiocardiographic evaluation.

The clinical, ECG, echocardiographic, and angiographic data, as well as the operative findings and postoperative courses of three children with intramural ventricular tumors are presented. In all three children, the specific diagnosis of intramural tumor was unsuspected. The ECGs showed a superior axis in all patients. M-mode echocardiography missed the mass in one patient and was nonspecific in the other two; however, two-dimensional echo (2DE) was able to accurately delineate the tumors preoperatively in all three. Angiographic findings were nonspecific, only demonstrating the presence of space-occupying lesions. All three patients underwent surgery and the tumors were removed successfully. This investigation emphasizes the clinical picture that led to the diagnostic evaluations, and demonstrates the usefulness of 2DE in accurately diagnosing the intramural ventricular tumors. In addition, the sequential ECGs and 2DEs after removal of the tumors are delineated as well as showing the resolution of the tumor craters by 2DE examinations.

Angiocardiography↗
PubMed1982

Long-term follow-up study after closure of secundum atrial septal defect in children: an echocardiographic study.

Serial echocardiography was performed in 51 children with isolated secundum atrial septal defect before and after surgery to measure the effects of chronic right ventricular overload on ventricular function. Right ventricular dilation increased dramatically with growth and with size of the left to right shunt only in the youngest children (body surface area less than 0.5 m2). A lesser effect of growth and no significant effect of shunt size were noted in older children. Although an initial decrease in right ventricular size occurred in the first 3 months after operation, persistent right ventricular dilation remained up to 5 years after closure of the interatrial defect in more than 80 percent of patients. Preoperatively, the ratio of the right ventricular preejection period to ejection time was significantly less than that of normal children. This ratio increased dramatically after operation, exceeding normal values early in the postoperative period in 18 of 48 children and persisting in 6 of 22 after 3 months. Left ventricular dimensions were normal early and late after operation. Left ventricular function was apparently normal, although an exceptionally high shortening fraction was noted in 22 (44 percent) of 51 children after operation. Aortic systolic time interval ratios decreased after operation from high normal to low normal values. It is hypothesized that the persistent enlargement of the right ventricle after operation may be due to the chronic preoperative dilation secondary to chronic interatrial shunting. The abnormally high shortening fraction after operation may result from an abnormal left ventricular geometric configuration or abnormality of filling. It is suggested that surgical closure of the atrial defect in the first 3 years of life may prevent these abnormalities.

Adolescent↗
PubMed1982

Exercise electrocardiogram, blood pressure, and working capacity in young patients with valvular or discrete subvalvular aortic stenosis.

Electrocardiographic changes, blood pressure, and working capacity (total work) were recorded during an upright cycle exercise test in 65 children and young adults (mean age 12 years) with valvular or discrete subvalvular aortic stenosis. All patients had cardiac catheterization, but none had surgical treatment. Controls consisted of 164 normal subjects (mean age 15 years). In the patients, the intervals between the exercise test and cardiac catheterization were 1 month or less in 66%, 2 to 12 months in 28%, and 12 to 24 months in 6%. The patients were classified by resting left ventricular to aortic peak systolic pressure gradient into Groups I (gradient less than 30 mm Hg), II (30 to 49 mm Hg), III (50 to 69 mm Hg), and IV (70 mm Hg or greater). The mean frequency and magnitude of exercise-induced S-T depression were greater in the patients than in the control subjects (p less than 0.005) and increased with increasing obstruction in the patients. Mean total work and peak exercise systolic pressure were significantly decreased in the patients with a left ventricular to aortic systolic gradient of 30 mm Hg or greater as compared with the control subjects (p less than 0.03). An exercise profile consisting of S-T depression of 2 mm or more, and markedly decreased total work and systolic blood pressure were characteristic of the 19 patients (Group IV) with a resting left ventricular to aortic systolic gradient of 70 mm Hg or greater. At least 2 or more components of this exercise profile occurred in 11 (24%) of the 46 patients with a resting left ventricular to aortic systolic gradient less than 70 mm Hg. This study demonstrates that exercise testing reveals serious abnormalities in patients otherwise classified as having trivial or moderate obstruction, and that a properly performed exercise study can be done at minimal risk to the patient.

Adolescent↗
PubMed1982

Phase I trial of 4-demethoxydaunorubicin with single i.v. doses.

Sixteen adult patients with a variety of solid tumors entered a phase I trial with 4-demethoxydaunorubicin, a new analogue of daunorubicin. The drug was given as a single i.v. dose of 5-18 mg/m2 repeated every 3-4 weeks. Myelosuppression, especially leucopenia, was dose-limiting. Other toxic effects included mild to moderate nausea and vomiting. The maximum tolerated dose for ambulatory treatment was 18 mg/m2, and 15 mg/m2 every 3-4 weeks is proposed as a starting dose for phase II trials in solid tumors.

Adult↗
PubMed1982

Genetic transformation of Rhodopseudomonas sphaeroides by plasmid DNA.

A broad-host-range cloning vector, pUI81, was constructed in vitro from plasmids RSF1010 and pSL25 (a pBR322 derivative) and used to assay for transformation in Rhodopseudomonas sphaeroides. Washing cells with 500 mM Tris was an effective means of inducing competence for DNA uptake. Transformation frequencies as high as 10(-5) (transformants per viable cell) have been achieved by incubating Tris-treated cells with plasmid DNA, 100 mM CaCl2, and 20% polyethylene glycol 6000. Maximum frequencies were obtained when recipient cells were spread onto selective media after a 6.5-h outgrowth period in antibiotic-free medium. The structure (open circular versus closed, covalent circular), size, and concentration of plasmid DNA all significantly affected the transformation frequency. Four different plasmids, all small and suitable as cloning vectors, have been introduced by transformation into several different R. sphaeroides strains. Recombinant DNA carried on small, nonconjugative plasmids with broad host ranges can now be directly transferred to R. sphaeroides by this method.

Calcium Chloride↗
PubMed1982

Alterations in the phospholipid composition of Rhodopseudomonas sphaeroides and other bacteria induced by Tris.

Alterations in the phospholipid head group composition of most strains of Rhodopseudomonas sphaeroides, as well as Rhodopseudomonas capsulata and Paracoccus denitrificans, occurred when cells were grown in medium supplemented with Tris. Growth of R. sphaeroides M29-5 in Tris-supplemented medium resulted in the accumulation of N-acylphosphatidylserine (NAPS) to as much as 40% of the total whole-cell phospholipid, whereas NAPS represented approximately 28 an 33% of the total phospholipid when R. capsulata and P. denitrificans respectively, were grown in medium containing 20 mM Tris. The accumulation of NAPS occurred primarily at the expense of phosphatidylethanolamine in both whole cells and isolated membranes of R. sphaeroides and had no detectable effect on cell growth under either chemoheterotrophic or photoheterotrophic conditions. Yeast extract (0.1%) and Casamino Acids (1.0%) were found to be antagonistic to the Tris-induced (20 mM) alteration in the phospholipid composition of R. sphaeroides. The wild-type strains R. sphaeroides 2.4.1 and RS2 showed no alteration in their phospholipid composition when they were grown in medium supplemented with Tris. In all strains of Rhodospirillaceae tested, as well as in P. denitrificans, NAPS represented between 1.0 and 2.0% of the total phospholipid when cells were grown in the absence of Tris. [32P]orthophosphoric acid entered NAPS rapidly in strains of R. sphaeroides that do (strain M29-5) and do not (strain 2.4.1) accumulate this phospholipid in response to Tris. Our data indicate that the phospholipid head group composition of many Rhodospirillaceae strains, as well as P. denitrificans, is easily manipulated; thus, these bacteria may provide good model systems for studying the effects of these modifications on membrane structure and function in a relatively unperturbed physiological system.

Membrane Lipids↗
PubMed1982

Kinetic analysis of N-acylphosphatidylserine accumulation and implications for membrane assembly in Rhodopseudomonas sphaeroides.

The accumulation of N-acylphosphatidylserine (NAPS) in response to the inclusion of Tris in the growth medium of Rhodopseudomonas sphaeroides strain M29-5 has been examined. In the accompanying paper (Donohue et al., J. Bacteriol. 152:000--000, 1982), we show that in response to Tris, NAPS accumulated to as much as 40% of the total cellular phospholipid content. NAPS accumulation began immediately upon addition of Tris and was reflected as an abrupt 12-fold increase in the apparent rate of NAPS accumulation. We suggest that Tris altered the flow of metabolites through a preexisting and previously unknown metabolic pathway. NAPS accumulation ceased immediately upon the removal of Tris; however, accumulated NAPS remained largely metabolically stable. Importantly, under conditions in which NAPS was not accumulated, the intracytoplasmic membrane was shown to be virtually devoid of newly synthesized NAPS. The significance of this observation is discussed in terms of its physiological implications on phospholipid transfer and membrane biogenesis in R. sphaeroides.

Cell Membrane↗
PubMed1982

Expression of the transposable lac operon Tn951 in Rhodopseudomonas sphaeroides.

The transposon Tn951 (lac) was introduced into the photosynthetic bacterium Rhodopseudomonas sphaeroides 2.4.1, which is normally Lac-, via the P-group plasmid RP1. beta-Galactosidase was produced constitutively in both chemotrophically and phototrophically grown cells, and the levels were found to be the same but low. Mutants were isolated, however, that were able to grow on lactose minimal medium and which expressed different levels of beta-galactosidase when grown chemotrophically or phototrophically. The beta-galactosidase levels found in all R. sphaeroides strains were much less than those found in Escherichia coli.

DNA Transposable Elements↗
PubMed1982

Early medical and surgical intervention for tetralogy of Fallot with absence of pulmonic valve.

Tetralogy of Fallot with absent pulmonic valve is a rare but life-threatening syndrome. Children with this complex may have aneurysmally dilated pulmonary arteries which compress the tracheobronchial tree and cause airway compromise and death. This paper reviews the course of 10 children with this syndrome who were seen at our institution from 1962 until the present. Two infants with respiratory distress secondary to tetralogy plus absent pulmonary valve were treated with early aggressive medical intervention followed by operation. After closure of the ventricular septal defect and reconstruction of the right ventricular outflow tract, the pulmonary artery aneurysms were resected. Both children are growing and are well more than 1 year after the operations. Our experience with these two patients suggests that such infants may benefit from this form of therapy.

Adolescent↗
PubMed1981

[Chemotherapy of non-small-cell bronchial cancer with a combination of Cis-diamminedichloroplatinum (II) and VP 16-213].

In a phase II study 40 patients with non-small-cell lung cancer were treated with 100 mg/m2 cis-diamminedichloroplatinum (II) (DDP) i.v. on day 1, combined with VP 16-213 (VP) in a dose of either 80 mg/m2 daily i.v. on days 1, 2 and 3 or 120 mg/m2 daily by mouth on days 3, 4, 5 and 6. The course was repeated every 3 weeks. In 30 evaluable patients, 10 partial remissions were recorded with a median duration of 3 months. Eleven patients had stable disease and 9 showed progression under treatment. Leukopenia was more pronounced with intravenous administration of VP than with oral VP (median leukocyte nadir 2400/mm3 and 3700/mm3 respectively). Two patients had thrombocytopenia under 50,000/mm3. All patients suffered from moderate to marked nausea and vomiting. All patients had alopecia. Nine patients had serum creatinine elevations over 1.4 mg/dl. Six patients with renal toxicity were treated in one institution with incorrectly applied forced diuresis during DDP administration. DDP and VP are an active regimen for remission induction in non-small-cell lung cancer. Due to cumulative and marked gastrointestinal intolerance this regimen cannot be given over prolonged periods of time.

Adenocarcinoma↗
PubMed1981

The non-detergent solubilization and isolation of intracytoplasmic membrane polypeptides from Rhodopseudomonas sphaeroides.

A nonspecific solubilization of the intracytoplasmic membrane proteins from Rhodopseudomonas sphaeroides has been achieved in the absence of detergents. Following removal of the photopigments and phospholipids by acetone/methanol extractions, the protein is quantitatively solubilized in 6 M guanidine thiocyanate which is subsequently exchanged by dialysis for 7 M urea. A urea-soluble protein fraction is obtained which represents 80% of the initial protein and qualitatively contains all the polypeptides of the membrane resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the exception of the reaction center polypeptides M and L, and the 35.2-kilodalton species. Fractionation of the urea-soluble polypeptides on a Sepharose CL-6B column resolves into separate fractions the two major low molecular weight polypeptides identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Further examination of these fractions by isoelectric focusing and electrophoresis at pH 4.5 in the presence of 8 M urea reveals the presence of three major species each of which has been purified to homogeneity by a combination of ion exchange chromatography and preparative electrophoretic techniques. It is believed that these three major polypeptides are components of the light-harvesting pigment-protein complexes.

Cell Membrane↗
PubMed1981

Characterization of the three major intracytoplasmic membrane polypeptides isolated from Rhodopseudomonas sphaeroides.

The characterization of the three major membrane polypeptides indicated to be subunits of the light-harvesting bacteriochlorophyll-protein complexes of Rhodopseudomonas sphaeroides is described. Molecular weight determinations of the three polypeptides have been performed by sedimentation analysis and electrophoretic mobility and the values obtained were in agreement with each other as well as with those derived from compositional studies. NH2- and COOH-terminal amino acid determinations were performed for each of the species; two of the polypeptides produces no reaction with dansyl chloride and were concluded to have blocked amino termini. In each instance, the data were consistent with each of the polypeptides being a single, pure species. Further characterization of the proteins was accomplished by amino acid compositional analysis and peptide mapping of tryptic and chymotryptic digestions of the polypeptides. The number of peptides obtained from the digestions was in agreement with the amino acid compositional data. Two of the polypeptides, 15B and 15C, which possess very similar molecular weights, identical carboxyl termini and apparently blocked amino termini were shown by amino acid analysis and peptide mapping to be structurally discrete species, although related. The relationship between these purified proteins and the known activities and characteristics of the light-harvesting bacteriochlorophyll-protein complexes of R. sphaeroides is discussed.

Amino Acids↗
PubMed1981

Vascular hypervolemia and hematoma formation in chick embryos treated with trypan blue.

The relationship between cardiovascular disturbances and the formation of hematomas in trypan blue-treated chick embryos was investigated. Hematocrits from Hamburger-Hamilton stage 15 and 16 embryos (8-10 hours after treatment at stage 13) were obtained. The hematocrit value from the treated embryos was significantly lower (P less than 0.001) than the values from controls. Unopened and saline-injected control values were not significantly different (P greater than 0.05). We interpret this to mean that there is excess circulating fluid volume in the treated embryos. The results of direct injection of measured volumes of fluid into the cardiovascular system of normally developing embryos (stages 15 and 16) provided evidence to suggest that the caudal dorsal aortae are susceptible to fluid-induced distension and rupture.

Animals↗
PubMed1981

Chaotic atrial tachycardia in childhood.

Ten cases of chaotic atrial tachycardia (CAT) in childhood are reported. Patients' ages ranged from 1 day to 18 years (average, 3.5 years) at the time of diagnosis. The patients were divided into groups according to the following criteria: (1) no cardiac disease (n = 5), (2) congenital heart disease (n = 4), and (3) acquired heart disease (n = 1). Nine of the children were treated with digoxin; however, it appears there was no beneficial effect. In fact, the single death in our study group may have been attributable to digitalis intoxication. No children have had recurrence of the arrhythmia after discontinuation of the drug. The duration of the tachyarrhythmia was extremely variable; however, CAT was well tolerated and was self-limiting in our patients.

Adolescent↗