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Biomedical subjects

S Kaplan

Publications and source records attributed to S Kaplan.

At least 451 records · Page 25Linked to original sources
PubMed1978

Effect of heat and 2-mercaptoethanol on intracytoplasmic membrane polypeptides of Rhodopseudomonas sphaeroides.

Solubilization at 75 degrees C of Rhodopseudomonas sphaeroides chromatophores in the presence of sodium dodecyl sulfate (SDS) and 2-mercaptoethanol (beta-ME) resulted in the selective absence of reaction center B and C polypeptides from SDS-polyacrylamide gel electrophoresis profiles. A newly identified, chromatophore-specific polypeptide, with a mass of 35.2 kdaltons, was also missing under these conditions of chromatophore solubilization. Solubilization at 27 degrees C in the presence of SDS and beta-ME also resulted in the disappearance of these three polypeptides, but at much slower rates. Disappearance of either endogenous or exogenously supplied reaction center polypeptides B and C during SDS solubilization of whole chromatophores at either 27 or 75 degrees C was shown to be entirely dependent upon the presence of beta-ME. After chromatophore solubilization in the presence of beta-ME and subsequent SDS-polyacrylamide gel electrophoresis, exogenously added reaction centers B and C could be localized in a complex of no less than 100 to 200 kdaltons. However, the precise size of the complex was influenced by the stoichiometry of the reacting components. The disappearance of the 35.2-kdalton polypeptide was neither dependent upon the presence of beta-ME nor dependent upon the presence of any additional chromatophore polypeptides. The 35.2-kdalton polypeptide underwent a heat-induced oligomerization to yield several high-molecular-weight species.

Bacterial Chromatophores↗
PubMed1978

Inconsistent expression of both centromeres of a dicentric Y chromosome in a child with ambiguous external genitalia.

A newborn child with ambiguous external genitalia had evidence of internal female development on the left and internal male development on the right. Blood chromosome analysis showed three cell types: 45,X; 46,XY with the Y being submetacentric and about twice the usual size with two 'centromeric' C bands; and 46,X,dic(Y). Chromosome studies from the skin, uterus, and Fallopian tube showed almost exclusively 45,X cells. This represents the second reported patient in whom two centromeres are inconsistently expressed though present as shown by two 'centromeric' C bands.

Azure Stains↗
PubMed1978

Temperature dynamics of the fertile chicken egg.

Two thermistor temperature probes were mounted in fertile chicken eggs, one at the position normally occupied by an early embryo and the other in the center of the yolk. Temperature changes were constantly monitored while the eggs were removed from holding refrigerator to incubator, incubator to room temperature, or room temperature to incubator. Computer analysis was used to develop a mathematical model of heat fluxes in the egg. Graphs derived from this model are presented which permit any investigator to predict approximate time and temperature variables under conditions commonly encountered when using the chicken egg in biological research. We found that when the egg is moved from an incubator (38 degrees C) to laboratory bench (25 degrees C), there was a very rapid initial heat loss (over 8 degrees C in 10 min) at a site in the egg which would be occupied by an early embryo. Conversely, when the egg is moved from the bench back to the incubator, nearly 2 h is required for the egg to recover 90% of the heat that it had lost while cooling to 25 degrees C.

Animals↗
PubMed1978

Effect of spinal cord transection on the endocrine and blood pressure responses to intravenous clonidine.

To determine whether the inhibitory effect of clonidine (CLON) on renin secretion is due in part to a direct action on the kidneys or due entirely to an action on the brain, the drug was administered intravenously in a dose of 30 microgram/kg to dogs in which the spinal cord had been transected in the cervical region. Renal perfusion pressure was held constant by adjusting a suprarenal aortic clamp. The decrease in plasma renin activity produced by CLON in dogs with intact spinal cords was abolished, and in 5 of 8 dogs tested, plasma renin activity rose. The decrease in blood pressure seen in control dogs was replaced by a prolonged pressor response. The ACTH response, as measured by plasma corticoids, and the growth hormone (GH) response were not significantly reduced. The data indicate that at least at this dose, the depressor response and the decrease in renin secretion produced by CLON are completely central in origin.

Adrenal Cortex Hormones↗
PubMed1978

Fast green staining of whole embryos for examination and photography.

Immersion for 15 seconds in a 1:1 solution of 0.25% fast green and 95% ethyl alcohol facilitates the examination of normal and abnormal embryos for gross surface morphology and renders their surface detail highly photogenic. The method does not interfere with subsequent histological staining when the embryos are sectioned.

Animals↗
PubMed1977

Expression and stability of Escherichia coli F-prime factors in Proteus mirabilis.

The expression and stability of Escherichia coli F-primes in Proteus mirabilis is examined. It is possible to consecutively introduce, and stably maintain, the DNA of several E. coli F-primes in P. mirabilis in the absence of selective pressure for all or some of the plasmids. Additionally, we can recover more than one F-prime from certain P. mirabilis recipient strains which carry DNA derived from several independent matings with E. coli F-prime donors.

Conjugation, Genetic↗
PubMed1977

Low-cost daily pacemaker monitoring system.

To reduce the cost of pacemaker monitoring, we developed an inexpensive cardiac pacemaker interval monitor that detects electromagnetic radiation of the electrical pulse generated by an implanted pacemaker. The pulse interval is timed by logic systems and a piezoelectric crystal. Pulse interval is computed to the nearest 0.1 msec. The device is battery powered and can be used at home by the patient to monitor pulse interval daily with little cost after the initial expenditure. The unit may also be used by the physician to detect the stability or constancy of random variation of the pulse interval. From a daily record of measurements of the pulse interval, limits are set by the physician to predict impending battery exhaustion. Eight patients have been monitored for up to 24 months.

Costs and Cost Analysis↗
PubMed1977

Leptospirosis: a childhood disease.

A diagnosis of leptospirosis was confirmed in nine children who were admitted to St. Louis Children's Hospital during the past 54 months. Epidemiologic, clinical, cultural, and serologic data which were obtained emphasize (1) the high incidence of urban cases; (2) contact with dogs as the most likely source of infection; and (3) that serotypes other than Leptospira icterohaemorrhagiae may produce severe clinical disease. Unusual or previously unreported manifestations of leptospirosis including acalculous cholecystitis, pancreatitis, abdominal causalgia, desquamating skin rashes, and infarction of the extremities which were noted in these children are discussed.

Adolescent↗
PubMed1977

Inappropriate secretion of antidiuretic hormone in children with bacterial meningitis.

A prospective study of bacterial meningitis in children was initiated two years ago. Serum sodium concentrations below 135 MEQ/liter were noted on admission in 72 of 124 (58.1 %) of patients enrolled in the study protocol. Low initial serum sodium concentration and prolonged depression in serum sodium despite fluid restriction correlated significanly (P less than 0.001 to 0.01) with the presence of neurologic sequelae of the disease. Inappropriate secretion of antidiuretic hormone as the cause of these electrolyte changes could be inferred by indirect measurement of serum and urine solute and volume data and was specifically documented, in patients enrolled most recently, by specific radioimmunoassay of antidiuretic hormone.

Adolescent↗
PubMed1977

Experience with reduction clitoroplasty for clitoral hypertrophy.

A technique for reduction clitoroplasty has been devised which provides an excellent cosmetic appearance for female patients with clitoromegaly due to virilizing CAH. Contrary to previous views, total clitorectomy should rarely, if ever, be considered as an initial method of management of children with clitoral hypertrophy. One of the 4 patients who has undergone reduction clitoroplasty using the described technique has achieved sexual gratification on several occasions postoperatively without discomfort.

Adolescent↗
PubMed1977

Left ventricular performance in the critically ill premature infant with patent ductus arteriosus and pulmonary disease.

Left cardiac dimensions and an index of left ventricular performance, the percent shortening of the internal diameter (%SID) of the left ventricle, were evaluated in premature infants who were asymptomatic, others with pulmonary disease and others with patent ductus arteriosus (PDA). In contrast to controls, left atrial and/or left ventricular end-diastolic dimensions were increased in all infants with clinical criteria of significant PDA. Postoperative dimensions decreased significantly. Percent SID values for normal premature infants (m=33.5%; SD=3.5%) and those with pulmonary disease alone did not differ significantly. In those with clinical criteria of PDA, who were subsequently found to have echocardiographic evidence of left cardiac enlargement, values for %SID were increased. As expected %SID values for individual patients represented a wider range of left ventricular function and/or afterload than for controls. Upon spontaneous or surgical closure of the PDA, %SID returned to normal. A PDA which is associated with left cardiac enlargement exhibits increased %SID, whereas decreasing %SID in the presence of increased dimensions suggests deteriorating myocardial performance. Echocardiography provides valuable insight into the cardiac status of these infants and may contribute to their medical and/or surgical management.

Ductus Arteriosus, Patent↗
PubMed1977

Echocardiographic evaluation of fixed left ventricular outlet obstruction in children. Pre and postoperative outlet obstruction in children.

Rencently, several investigators have utilized the echographically determined magnitude of relative left ventricular posterior wall hypertrophy as a reflection of normalized systolic wall stress to estimate left ventricular systolic pressure noninvasively. In this study, relative wall thickness determined echographically was compared to peak systolic pressure measured at catheterization in 20 children without obstruction to left ventricular outflow and with normal left ventricular function. From these data a relationship, pressure = 225 X left ventricular systolic wall thickness/left ventricular end-systolic internal dimension, was derived. The relationship was then applied to 57 children with fixed aortic stenosis. Left ventricular pressure estimated echographically compared well with that demonstrated at cardiac catheterization (r = 0.89). Twenty-one patients had further echographic studies following surgical relief of outlet obstruction. Estimated left ventricular pressure fell to normal values within two months following surgery in over half the patients with good surgical relief of obstruction, and was normal at subsequent studies up to 22 months postoperatively in all but one patient with good surgical relief. In patients in whom outlet obstruction was not adequately relieved at surgery, echographically estimated left ventricular pressure remained persistently elevated.

Adolescent↗
PubMed1976

Left ventricular function by echocardiography in children with fixed aortic stenosis.

Left ventricular function was evaluated echocardiographically within 24 hours of cardiac catheterization in 45 children with fixed aortic stenosis. Left ventricular systolic time intervals, mean velocity of circumferential fiber shortening, left ventricular end-diastolic volume and shortening fraction were evaluated. Some patients with severe aortic stenosis had a shortened preejection period, prolonged ejection time and increased mean velocity of circumferential fiber shortening in comparison with normal subjects, but these findings were not consistent within the group with severe aortic stenosis or apparent in patients with mild or moderate aortic stenosis. Left ventricular end-diastolic volume was smaller in children with severe obstruction than in normal children. Evaluation of the shortening fraction provided good separation of patients with significant obstruction from those with mild disease. Further, there was a linear correlation between the shortening fraction and the left ventricular-aortic gradient demonstrated at cardiac catheterization. This correlation was also of use in evaluating the response of patients to surgical relief of obstruction. Pre- and postoperative echocardiographic evaluation of the shortening fraction appears to provide a readily available noninvasive method of assessing the course and severity of obstruction in fixed aortic stenosis in children.

Adolescent↗
PubMed1976

Transcription of Escherichia coli ribosomal DNA in Proteus mirabilis.

Transcription of Escherichia coli ribosomal DNA introduced into Proteus mirabilis on F14 is described. We have developed an assay for E. coli coded ribosomal RNA involving fingerprinting of ribonuclease T1 digests of RNA isolated from ribosomal subunits. Sequence differences in the ribosomal RNA of the two species have allowed us to detect E. coli coded 16S, 23S, and 5S ribosomal RNA in ribosomal subunits of the E. coli-P. mirabilis hybrid. The proportion of E. coli coded rRNA in the hybrid is found at a level which is compatible with the number of E. coli (and P. mirabilis) ribosomal DNA sequences. The resulting ribosomal RNA appears in ribosomes in a form which indicates extensive compatibility of E. coli coded ribosomal RNA with P. mirabilis ribosomal proteins and maturational factors.

Base Sequence↗