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Biomedical subjects

S Kaplan

Publications and source records attributed to S Kaplan.

At least 415 records · Page 23Linked to original sources
PubMed1980

Cardiac septal hypertrophy in hyperinsulinemic infants.

One infant with nesidioblastosis, and five of 18 infants of diabetic mothers had echocardiographically determined septal hypertrophy (greater than or equal to 6 mm). No correlation was found between the septal hypertrophy and the presence of hypocalcemia, polycythemia, birth asphyxia, or other observed clinical findings. All of the infants with septal hypertrophy, however, had profound hypoglycemia shortly after birth in contrast to those infants without septal hypertrophy. Macrosomic IDM have intrauterine hyperglycemia and hyperinsulinemia. The presence of profound neonatal hypoglycemia is consistent with the metabolic effects of significant neonatal hyperinsulinemia which is also present in the fetus. Infants with nesidioblastosis also have fetal hyperinsulinemia. Recent investigations have suggested an important role for insulin in the developing heart since it is rich in insulin receptors and contains marked insulin degrading capacity. Although fetal hyperglycemia has been suggested as the cause of septal hypertrophy in IDM, we hypothesize that fetal hyperinsulinemia contributes directly to the spinal hypertrophy.

Cardiomegaly↗
PubMed1980

Management of infective endocarditis using echocardiography.

Serial echocardiograms of five children who had infective endocarditis were analyzed and correlated with the clinical course. Vegetations were visualized initially on M-mode in four and on two-dimensional echocardiograms in all patients. The appearance of the vegetation was unexpected in one. More accurate anatomic localization of the vegetation was possible using two-dimensional echography. Four of the five patients died despite vigorous medical treatment and valve replacement in two. Complete resolution of the vegetation was documented for the first time in a child following medical therapy. This study suggests that echocardiography plays an important role in the diagnosis of endocarditis, allows objective follow-up of the size of the vegetations and their effects on valve function, and, therefore, may prove helpful in the management of these patients.

Adolescent↗
PubMed1980

RsaI: a new sequence-specific endonuclease activity from Rhodopseudomonas sphaeroides.

A new type II sequence-specific endonuclease, RsaI, has been identified from Rhodopseudomonas sphaeroides strain 28/5. An RsaI purification scheme that yields enzyme which is free of contaminating exonuclease and phosphatase activities after a single column fractionation has been developed. The enzyme recognized the tetranucleotide sequence 5'-GTAC-3' and cleaved between the T and A, thereby generating flush ends. RsaI should be extremely useful in deoxyribonucleic acid sequencing experiments.

Base Sequence↗
PubMed1980

Protein composition of Rhodopseudomonas sphaeroides outer membrane.

The outer membrane polypeptide profile of Rhodopseudmonas sphaeroides was characterized. Solubilization of the outer membrane at 75 or 100 degrees C as opposed to room temperature resulted in the dissociation of 75-, 72-, and 68-kilodalton (kdal) polypeptide aggregates into 29-, 26.5-, and 21.5-kdal polypeptides, respectively, and a shared 47-kdal subunit. Similarly, an 88.5-kdal polypeptide dissociates into a 45-kdal monomeric form, and the electrophoretic mobility of a 58.5-kdal polypeptide was altered to 83 kdal. Lysozyme treatment of outer membrane fractions altered the 21.5-kdal polypeptide mobility to 23 kdal. The presence of lipid in both the 47-kdal polypeptide and an 8- to 10-kdal polypeptide was demonstrated by lipid staining and [14C]acetate incorporation. The lipid component of the 47-kdal polypeptide was neither lipopolysaccharide nor phospholipid. The 8- to 10-kdal polypeptide may be the equivalent of the Braun lipoprotein. Outer membrane fractions isolated from R. sphaeroides-specific phage RS1-resistant mutants were deficient in several of the high-molecular-weight aggregates involving the 47-kdal polypeptide.

Bacterial Proteins↗
PubMed1980

Responses of normal children and young adults to controlled bicycle exercise.

Exercise responses were obtained from 149 children and young adults (average age 14.5 years) and divided by sex and body surface area (BSA): children with BSA less than 1 m2; children with BSA 1--1.19 m2; males with BSA greater than or equal to 1.2 m2; and females with BSA greater than or equal to 1.2 m2. Total work, mean and maximal power outputs were more affected by body size (height) than age in children with BSA less than 1 m2 and in males and females with BSA greater than or equal to 1.2 m2. Mean systolic pressure increased up to 64% above the preexercise supine value at peak effort, with the level of mean maximal systolic pressure having a positive relationship with body size (height), power output and preexercise sitting systolic pressure in all subgroups except children with BSA 1--1.19 m2. Mean diastolic pressure increased up to 24% above the preexercise supine value at peak effort. ST-segment depression of 1--2 mm was recorded in 12.1% (18 of 149) of the population at peak exercise. These changes occurred in 8.9% of all males and in 16.9% of all females (p greater than 0.1). The data from this study reveal the importance of sex and body size in the clinical interpretation of exercise responses in growing subjects, provide a reference for objective evaluation of subjects with or without cardiac abnormalities and provide a guide for careful monitoring of subjects during an exercise study.

Adolescent↗
PubMed1980

Ventricular tachycardia in infancy: evidence for a reentrant mechanism.

Ventricular tachycardia is unusual in infancy. Three infants are described in whom this arrhythmia was documented by electrophysiologic studies. The ability to start and terminate this rhythm by critically timed premature ventricular stimulation suggests a reentrant mechanism. All three patients have remained free of arrhythmias on oral propranolol therapy.

Electrophysiology↗
PubMed1979

Intermembrane phospholipid transfer mediated by cell-free extracts of Rhodopseudomonas sphaeroides.

The transfer of phospholipids between two membrane substrates catalyzed by a soluble protein fraction from Rhodopseudomonas sphaeroides has been demonstrated. The assay employs purified intracytoplasmic membrane (ICM) vesicles derived from cells of R. sphaeroides grown on [3H]acetate as the phospholipid donor substrate and phosphatidylcholine (70%)/phosphatidylethanolamine (30%) unilamellar liposomes containing [14C]triolein, a nontransferable marker, as the acceptor substrate for transferred phospholipids. Incubation of these two membrane substrates with a 40 to 80% (NH4)2SO4 protein fraction from R. sphaeroides results in the transfer of tritium-labeled ICM phospholipids to the acceptor membrane substrate. Upon completion of the incubation period, the donor ICM vesicles are quantitatively separated from the acceptor liposomes by precipitation with antibody prepared against whole, purified ICM vesicles. Phospholipid transfer is linear with respect to time and protein concentration, is inhibited by trypsin and heat, and shows an absolute dependence upon the presence of acceptor liposomes and the 40 to 80% (NH4)2SO4 protein fraction. Control experiments indicate that no fusion of the donor and acceptor membrane occurs during the incubation period and that, following prolonged incubation there is no detectable degradation of the labeled lipid components. Preliminary data on the phospholipid specificity of the transfer reaction is also presented.

Biological Transport↗
PubMed1979

Amphetamines reduce embryonic size and produce caudal hematomas during early chick morphogenesis.

Experiments were designed to study some of the similarities and differences in the effects of amphetamines and trypan blue on early chick morphogenesis. Both dextroamphetamine sulfate (0.5 mg/egg) and methamphetamine hydrochloride (1.0 mg/egg) were capable of inducing, in 3-day chick embryos, caudal hematomas which were similar in appearance and location to those routinely observed following treatment with trypan blue. It was found, too, that both dextroamphetamine and methamphetamine treated embryos frequently exhibited a significant decrease in crown rump length and cross-sectional area of the notochord, neural tube, dorsal aortae and whole body section, when compared with unopened or saline injected controls. Trypan blue treated embryos had only a rare decrease or increase in the size of structures when compared to either control group. These findings suggest that the amphetamines have an ability to decrease or retard embryonic growth in the chick.

Abnormalities, Drug-Induced↗
PubMed1979

Accelerated ventricular rhythm in childhood.

Four patients, aged 6 to 14 years, with accelerated ventricular rhythm were studied from June 1976 to June 1978. Three were asymptomatic and had no evidence of cardiac disease. One patient had equivocal evidence of myocarditis. All four patients are well without therapy. The benign nature of this rhythm and the importance of its differentiation from ventricular tachycardia is stressed.

Adolescent↗
PubMed1979

Nitroprusside and epinephrine for treatment of low output in children after open-heart surgery.

We evaluated the acute hemodynamic effects of treatment of the low output state with sodium nitroprusside and epinephrine in 13 children after intracardiac operation. The 13 patients were selected from a consecutive series of 106 children undergoing cardiopulmonary bypass. They had a cardiac index less than 2.0 L/min/m2, even after an increase in left ventricular filling pressure and during infusion of nitroprusside. Although the nitroprusside brought about a significant increase in cardiac output and decrease in systemic vascular resistance, the cardiac index remained critically low (less than 2 L/min/m2). Epinephrine resulted in a further significant increase in the cardiac index, without a significant change in systemic resistance. This study suggests that in selected patients the simultaneous use of both a vasodilator drug (sodium nitroprusside) and a positive inotropic agent (epinephrine) is advantageous in the short-term treatment of the low cardiac output state after intracardiac operation.

Adolescent↗
PubMed1979

Entrapment of a bacterial plasmid in phospholipid vesicles: potential for gene transfer.

Entrapment of pBR322 DNA within liposomes was demonstrated by (i) its comigration with liposomes on Sepharose 4B columns, (ii) resistance of its biological activity to DNase digestion, and (iii) identification of plasmid DNA on agarose gels after lipid extraction. The biological activity of the liposome-entrapped plasmid was determined by transformation assays. The incubation of intact liposomes, containing entrapped pBR322, with competent Escherichia coli cells in the standard transformation mixture resulted in the appearance of tetracycline-resistant colonies at a frequency of 1% of the control frequency. Importantly, this frequency was unaffected by the addition of DNase to the incubation mixture, whereas transformation by free pBR322 DNA was totally eliminated after treatment with DNase.

Cytoplasm↗
PubMed1979

Comparison of stainable iron in aspirated and needle-biopsy specimens of bone marrow.

A comparison of stainable iron in simultaneously obtained aspirated smears and needle-biopsy specimens from 1,000 patients was undertaken. Significant differences occurred when iron was assessed as absent in the aspirated smear. In only 35% of the corresponding needle-biopsy specimens was iron absent. When only the aspirated smear was used, there was a significant overdiagnosis of iron deficiency. In general, iron tended to be less in the aspirated smear; however, correlations were better when iron stores were assessed as being present or increased in the aspirated smears, for stainable iron in the needle-biopsy specimen was always present in equal or greater amounts. Hemosiderotic smears (increased stainable iron) and needle-biopsy specimens (3+ -4+) correlated well. The aspirated smear and needle-biopsy are complementary procedures, and each has advantages. In the authors' experience, the needle-biopsy was preferable to the aspirated smear for evaluation of iron stores, particularly when iron stores were low or absent.

Biopsy, Needle↗
PubMed1979

Characterization of a site-specific restriction endonuclease from Rhodopseudomonas sphaeroides.

A type II restriction endonuclease, RshI, has been partially purified from photoheterotrophically grown Rhodopseudomonas sphaeroides strain 2.4.1. The enzyme preparation, after a single DE-52 column fractionation, is free of 5' exonuclease and phosphatase activities but contains a trace of 3' exonuclease activity. Based upon deoxyribonucleic acid (DNA) sequencing data in the vicinity of the enzyme-promoted cleavage of pBR322 DNA, we have concluded that RshI probably recognizes the palinodromic hexanucleotide sequence 5'-CGATCG-3' and cleaves between the T and C. lambda cI857 DNA contains three RshI sites, two of which lie in the replaceable region. The plasmid pBR322, which carries resistances to ampicillin and tetracycline, contains a single RshI site in the ampicillin resistance determinant. Insertion of DNA into the RshI site of pBR322 results in loss of ampicillin resistance but retention of tetracycline resistance, thereby providing a convenient screening procedure for recombinant plasmids.

Base Sequence↗
PubMed1979

Oxygen consumption by chick embryos exposed to mechanical (shaking) stress.

Stage 34 (8-day) and 41 (15-day) chick embryos (Gallus gallus; in ovo) were exposed (3 min) to two separate amounts of mechanical (shaking) stress. Oxygen consumption determinations, following a temperature equilibration period (60 min), were made on entire, intact eggs using a Warburg apparatus equipped with 130-ml flasks modified to hold the egg. Shaking at 300 excursions per minute (epm) resulted in depressed O2 consumption by stages 34 and 41. Only stage 34 embryos had markedly depressed O2 consumption values when shaken at 100 epm. When exposed to 300 epm and reincubated for either 1, 2, or 4 hr prior to O2 consumption determinations stage 34 embryos, following an early return to control levels exhibited a marked fall in O2 consumption by 4 h reincubation. The stage 41 embryos, on the other hand, demonstrated a gradual rise to control O2 consumption levels by 4 h reincubation. Oxygen consumption has now been shown for the first time in an embryonic system (at two distinct developmental stages) to be functionally impaired by mechanically induced stress.

Animals↗