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Biomedical subjects

C H Smith

Publications and source records attributed to C H Smith.

At least 181 records · Page 10Linked to original sources
PubMed1980

Carotid sinus reflex in patients undergoing coronary angiography: relationship of degree and location of coronary artery disease to response to carotid sinus massage.

Heart rate and blood pressure responses during and after carotid sinus massage were examined in 66 patients just before coronary angiography. A significant relationship was found between heart rate and blood pressure responses and (1) angina pectoris class, (2) total coronary artery disease score and (3) presence of high-grade (> 90%) stenosis of any of the three major coronary arteries. Only patients with contraction abnormalities of the anterolateral left ventricular region had greater cardionhibitory responses than patients with normal left ventricular angiograms. Among patients with normal left ventricular angiograms, those with more than 50% stenosis of one or more vessels had significantly (p < 0.01) greater responses than those with no or minimal coronary artery disease. All 21 hypersensitive (asystole longer than 3 seconds) patients had significant multivessel coronary artery stenoses or single-vessel high-grade stenosis (greater than or equal to 90%) proximal to the atrioventricular nodal artery. None of the 11 patients with normal coronary arteries had an exaggerated response to carotid sinus massage. These data support the association of an exaggerated response to carotid sinus massage in the presence of symptomatic coronary artery disease and suggest that the magnitude of response is influenced by the severity of the disease.

Adolescent↗
PubMed1980

Transferrin receptors on the human placental microvillous membrane.

A preparation of microvillous membrane vesicles from human placental syncytiotrophoblast binds transferrin to specific transferrin receptors. Transferrin binding to placental receptors is rapid, saturable, reversible, and specific. Approximately 2.5 X 10(13) receptors are present per milligram of membrane protein; the apparent association constant of transferrin for the placental receptor is 2.2 X 10(7) X M-1. No evidence for removal of iron from transferrin bound to intact membrane receptors was observed in these studies. Nonionic detergent solubilization and partial purification of the microvillous membrane transferrin receptor were carried out with preservation of the functional properties of the receptor.

Female↗
PubMed1980

Presenile Alzheimer disease: amyloid plaques in the cerebellum.

Seven of 24 patients with pathologically proved Alzheimer disease had amyloid plaques resembling kuru plaques in the cerebellum. In all seven patients, the dementia was presenile in onset, there was a positive family history of the disease in five patients, and other neurologic symptoms were present in five. Similar plaques have been described in one of two patients with familial Alzheimer disease from whom spongiform encephalopathy was induced in subhuman primates after intracerebral inoculation of brain tissue. These observations suggest that some cases of familial Alzheimer disease may be clinically distinct from senile dementia and may not be genetic in origin.

Adult↗
PubMed1980

Integrating the teaching of sickle cell anemia into the curriculum of the Cincinnati public school system.

In an effort to determine the impact of one aspect of the Cincinnati Comprehensive Sickle Cell Center's educational program, a study of the level of knowledge of sickle cell facts by elementary and secondary school students in the Cincinnati public school system was conducted. An underlying assumption of this study was that a specially adapted sickle cell teaching curriculum in conjunction with in-service training for science teachers by sickle cell education staff was effective and practical. The study provided support for this assumption and has important implications for educating the general public about sickle cell disease and sickle cell trait. This study was undertaken during the 1975-1976 school year, and has subsequently led to the adoption of this sickle cell teaching curriculum by the Cincinnati Board of Education.

Anemia, Sickle Cell↗
PubMed1979

Insulin and placenta: degradation and stabilization, binding to microvillous membrane receptors, and amino acid uptake.

Human placenta possesses insulin receptors, yet whether insulin affects uptake of substrate or other placental functions is still controversial. A potential problem in the study of this issue is degradation of insulin by placental tissue. We found insulin degradation to be rapid and temperature dependent. At 10 mU/ml and 37 degrees C, 40% became trichloroacetic acid soluble within 15 minutes. Degradation was decreased by preincubation of tissue, followed by change of medium and by addition of 0.5% to 2.0% bovine albumin. Receptor assay with isolated microvillous membrane, which bound insulin with the characteristics of known target tissues, demonstrated biologically active insulin (5 to 6 mU/ml) to persist under incubation conditions. The presence of insulin did not influence the uptake of amino acids by the three neutral amino acid transport systems of the human placenta. Thus the transport of an essential fetal nutrient is is apparently independent of fluctuations in maternal insulin with dietary carbohydrate intake and disease.

Amino Acids↗
PubMed1979

Assay of theophylline: comparison of EMIT on the ABA-100 to HPLC, GLC and UV procedures, with detailed evaluation of interferences.

The EMIT technique for theophylline measurement as adapted to the Abbott Bichromatic Analyzer (ABA-100), was compared to two other established procedures. EMIT results correlated well with those obtained with high pressure liquid chromatographic (HPLC) (r = 0.995, N = 54) and spectrophotometric (UV) (r = 0.95, N = 37) methods when the patient samples used were free of apparent interferences in the comparison methods. On samples exhibiting interferences with HPLC and/or UV methods, the EMIT assay gave the same results as a gas-liquid chromatographic procedure which showed no interferences. In addition, theophylline metabolites, xanthine analogs and many commonly administered drugs did not interfere with the EMIT theophylline assay. An interassay coefficient of variation of 3.5--6.5% was demonstrated. Our data indicate that the EMIT technique exhibits adequate precision and specificity for routine theophylline determinations. Unlike the HPLC or UV procedures, we have not encountered any interferences with the EMIT technique.

Chromatography, Gas↗
PubMed1978

Placental amino acid uptake. IV. Transport microvillous membrane vesicles.

The recent characterization of a vesicular microvillous plasma membrane preparation from human placenta has made possible study of the characteristics of amino acid transport by the isolated membrane. Variation of medium osmolality demonstrated that alpha-aminoisobutyric acid (AIB) is taken up virtually entirely into a vesicular space. Vesicular volume was determined from equilibrium uptake of three dissimilar nonamino acid substrates, all of which gave a common value. Temperature dependence, saturability, specificity, and similarity of kinetic constants all indicated that AIB uptake by the vesicles resembles that by whole villous tissue. AIB uptake was stimulated specifically by an inward sodium gradient and unaffected by an outward potassium gradient. The persistence of stimulation up to 2 h after the gradient was established could be correlated with the slow equilibration of sodium across the membrane. AIB exodus could be studied with minimal problems of substrate recapture by using preloaded membrane vesicles bound tightly to cellulose ester filters to facilitate transfer to fresh medium. The exodus process was saturable with a Km considerably greater than that for entry.

Alkaline Phosphatase↗
PubMed1977

Characterization of a microvillous membrane preparation from human placental syncytiotrophoblast: a morphologic, biochemical, and physiologic, study.

The syncytiotrophoblast microvillous membrane must play a vital role in many essential functions of the placenta. In order to better understand the functional characteristics of this membrane, we have investigated an isolated membrane preparation by a variety of techniques. Electron microscopic observations showed membranous structures similar to microvilli of intact placental villi in size, shape, and microfilamentous content. Similarities in colloidal iron staining and transferrin localization were also shown. The preparation was enriched in enzymes characteristic of surface membranes and diminished in enzymes characteristic of intracellular organelles. Sialic acid content was also increased. SDS gel electrophoresis revealed the presence of a 45,000 molecular weight band, which may be actin. The preparation transported serine, glycine, and alpha-aminoisobutyric acid by a temperature-dependent, saturable process.

Alkaline Phosphatase↗
PubMed1976

The nonuniform distribution of acidic components on the human placental syncytial trophoblast surface membrane: a cytochemical and analytical study.

The surface coat of syncytial trophoblast from term human placentas was studied using cytochemical methods (colloidal iron, alcian blue-lanthanum nitrate, dialyzed iron) in coordination with tissue enzyme digestions (trypsin, neuraminidase) and sialic acid analyses. The presence of at least two highly acidic anionic components that contribute significantly to the surface negativity of trophoblast has been demonstrated. The first of these, sialic acid, was removed with neuraminidase. Tissue digestion with this glycosidase was accompanied by a decrease in trophoblast surface staining with colloidal iron, a decrease in tissue sialic acid, and an increase in the concentration of sialic acid in the incubating medium. Results from methylation experiments were consistent with the presence of sialic acid. The second anionic component(s) was identified by removal with trypsin of a glycocalyx constituent that stained with both colloidal iron and lanthanum. After trypsinization, tissue sialic acid levels were not significantly different from control values, and no detectable sialic acid was present in the incubating medium. The identity of this anionic component has not been established. Both sialic acid and nonsialic acid acidic components are distributed in higher density on membrane of microvilli than on intermicrovillous surface membrane. In addition, the sialic acid moieties appear to be clustered in the glycocalyx.

Acids↗
PubMed1976

Placental amino acid uptake. III. Transport systems for neutral amino acids.

The human placenta is known to concentrate nearly all amino acids intracellularly for transfer to the fetus. To clarify the mechanism and regulation of this process we have determined the specificity of the principal placental transport systems for neutral amino acids. With the use of competitive inhibition techniques, three transport systems of overlapping specificity have been elucidated. These correspond approximately to the "A", "L", and "ASC" systems of Christensen and associates. In the placenta the specificity of these systems is as follows: A system - alpha aminoisobutyric acid (AIB), glycine, proline, N-methylalanine, alanine, serine, threonine, and glutamine; L system - isoleucine, valine, phenylalanine, BCH, alanine, serine, threonine, and glutamine; and ASC system - alanine, serine, threonine, and glutamine. Placental AIB uptake previously has been shown to increase with preincubation of tissue in vitro. This increase has now been found to be limited to the A system. Activity of the other two systems is essentially unaffected, demonstrating that the transport pathways are separately regulated.

Amino Acids↗
PubMed1976

Microscale modification of a cation-exchange column procedure for plasma ammonia.

A column cation-exchange resin procedure for plasma ammonia was modified to require only 100 mul of plasma per determination. Mean analytical recovery of standard from resin (six samples) was 98% (range, 94-100%) as compared to a mean of 63% (range, 58-70) for nine samples when a batch cation-exchange procedure was used. Absorbance was proportional to sample concentration up to 800 mumol/liter. Analytical recovery of standard from plsma (six samples) was complete (mean, 103%; range, 90-113). Thirteen aliquots of a specimen of fresh plasma from a single adult individual gave a mean value of 20 mumol/liter (range, 11-26). The mean plasma venous ammonia concentration for 27 adults was 16 mumol/liter (range, 0-39), and for 15 newborns it was 60 (range, 34-102). Values for capillary plasma measured at the same time were higher, and we discuss possible explanations for this. Values are given for infants and children from one month to 14 years of age. Effects of storage time and temperature on plasma ammonia concentration are discussed.

Adolescent↗
PubMed1976

Stabilization of blood glucose by cooling with ice: an effective procedure for preservation of samples from adults and newborns.

Glycolysis causes a considerable decrease in blood glucose when whole blood is kept at room temperature without preservative. The most commonly used preservative, NaF, makes analysis of other serum constituents such as sodium and calcium and urea difficult or impossible, an especially serious limitation when sample size must be restricted. In samples at room temperature without preservative, plasma glucose decreased 36 mg/liter per hour in blood from adults and 60 mg/liter per hour in blood from newborns. Cooling on ice slowed these rates to 3.9 and 11, respectively. Plasma potassium increased 0.3 mmol/liter per hour in cooled specimens from both adults and newborns. Sodium, calcium, chloride and urea values were unaffected. We conclude that cooling effectively stabilizes plasma glucose for 4 h in samples from both adults and newborns and that potassium may be measured with negligible change for as long as 1 h and other constituents for the entire period.

Adult↗
PubMed1976

Erythrocyte porphyrin analysis in the detection of lead poisoning in children: evaluation of four micromethods.

We evaluated four procedures for determination of erythrocyte porphyrin: double extraction with ethyl acetate/acetic acid-HCl, single extraction with ethanol, single extraction with acetone, and direct solubilization with detergent-buffer. The ethyl acetate procedure, when used with two portions of HCl, apparently gives complete recovery of porphyrin and is suitable for reference as a comparison method. The ethanol procedure gives a high and consistent recovery and is technically simpler. The acetone procedure gives low and variable recovery of porphyrin, and the detergent-buffer method is subject to serious hemoglobin interference; neither of these two procedures offers any technical advantage. Stability of samples and methods for standardization were explored. A procedure for expressing results in terms of erythrocyte Zn-protoporphyrin content is given. Because of its stability, coproporphyrin is useful as a daily working standard. The ethyl acetate and ethanol methods are about equally efficient for detecting lead intoxication. Because of its simplicity, the ethanol method seems to be the best for use in screening.

Acetates↗
PubMed1975

Neuraminidase assay of influenza vaccines.

At present influenza vaccines are standardized on their haemagglutinin content only. Recently it has been shown that both neuraminidase and haemagglutinin antibodies are important in providing protection against the influenza virus. We have, therefore, developed an automated neuraminidase assay, based on the enzymic method of Kendal, but modified to minimise the interference by sucrose. A neuraminidase standard has been established and samples assayed against the standard have a coefficient of variation of plus or minus 6.8 percent. The assay has been adapted to measure the neuraminidase antibody level in serum. The neuraminidase to haemagglutinin ratio has been determined for various influenza strains. Both neuraminidase and haemagglutinin titres are being compared with results obtained by the single radial diffusion method.

Antibodies↗