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Biomedical subjects

J Peters

Publications and source records attributed to J Peters.

At least 505 records · Page 28Linked to original sources
PubMed1987

[Control interval].

Explore the source record for details and available documents.

Appointments and Schedules↗
PubMed1986

Changes in rats' meal patterns as a function of the caloric density of the diet.

Rats in a laboratory foraging paradigm were offered each of four diets which differed in caloric density, and intakes, meal frequencies, meal sizes, and eating rates were monitored. The rats maintained a constant daily caloric intake by eating more frequent, larger meals of the lower density foods. However, caloric meal size was not regulated, and significant correlations between meal size and the length of the post-meal interval were rarely found. The 24-hour pattern of calorie intake was the same regardless of diet. Higher-calorie foods were consumed at a faster rate within meals than were lower-calorie foods. The feeding patterns observed suggest that caloric intake may be regulated over a time frame of several meals rather than on a meal-to-meal basis.

Adaptation, Physiological↗
PubMed1986

Left ventricular diastolic filling in children with hypertrophic cardiomyopathy: assessment with pulsed Doppler echocardiography.

Altered left ventricular filling patterns in hypertrophic cardiomyopathy have been demonstrated by M-mode echocardiographic and radionuclide techniques. Because pulsed Doppler ultrasound provides the capability to directly measure blood flow velocity across the mitral valve, it was hypothesized that this technique would be useful for demonstrating left ventricular filling abnormalities. Simultaneous Doppler ultrasound examination of the left ventricular inflow, M-mode echocardiograms and phonocardiograms were performed in 17 children and young adults: 10 with hypertrophic cardiomyopathy (aged 6 to 20 years) and 7 with a normal heart (aged 10 to 18 years). From the Doppler studies, measurements of various diastolic time intervals, peak flow velocity during rapid filling (E velocity) and peak flow velocity during atrial contraction (A velocity) were made. Several areas within the Doppler flow envelope were calculated: first 33% of diastole (0.33 area), first 50% of diastole, triangle under the E velocity (E area) and triangle under the A velocity (A area). These were expressed as a percent of area under the total flow envelope. From the M-mode studies, left ventricular endocardial echoes were digitized and peak rates of increase in left ventricular dimension were determined and normalized for end-diastolic dimension. Diastolic time intervals, including isovolumic relaxation time, were calculated using the phonocardiogram to determine end-systole. The E velocity was lower (0.71 +/- 0.23 versus 0.91 +/- 0.11 m/s, p less than 0.05), 0.33 area/total area was less (0.46 +/- 0.11 versus 0.58 +/- 0.08, p less than 0.05) and the isovolumic relaxation time was prolonged (56 +/- 2 versus 31 +/- 1 ms, p less than 0.05) in patients with hypertrophic cardiomyopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Comparison of high pulse repetition frequency and continuous wave Doppler echocardiography for velocity measurement and gradient prediction in children with valvular and congenital heart disease.

To compare the ability of high pulse repetition frequency and continuous wave Doppler echocardiography to detect the peak velocity of a jet flow disturbance and to predict pressure gradients accurately, two groups of children with valvular or congenital heart disease were examined using both Doppler techniques. The use study group included 84 children or adolescents (aged 1 day to 19 years) who underwent examination in the echocardiography laboratory with both Doppler techniques in a randomized sequence. The peak velocity recorded with high pulse repetition frequency Doppler echocardiography was compared with the peak velocity recorded with the continuous wave technique. The accuracy study group included 41 children or adolescents (aged 1 day to 16 years) who underwent examination with both Doppler techniques at the time of cardiac catheterization. Doppler pressure gradients were calculated from the peak velocity using the simplified Bernoulli equation and were compared with peak instantaneous gradients and peak to peak gradients measured at catheterization. In the use study, a high correlation was found between peak velocities detected by high pulse repetition frequency and continuous wave Doppler echocardiography (r = 0.94, SEE = 0.28 m/s). In the accuracy study, close correlations were found between measured peak to peak pressure gradients and pressure gradients calculated from continuous wave (r = 0.95, SEE = 7.9 mm Hg) and high pulse repetition frequency Doppler echocardiography (r = 0.94, SEE = 8.7 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Deficiency of adenosine deaminase in the wasted mouse.

Wasted (wst) is a spontaneous mutation with autosomal recessive inheritance. Abnormally low levels of adenosine deaminase have been found in erythrocytes from the wasted mouse. Enzyme activity in wst/wst mice is reduced to 38% of that found in the erythrocytes from control mice, and the apparent Km for adenosine is reduced to 51% of control. These changes imply an alteration in the catalytic properties of the enzyme arising from a change in the primary structure of the protein. We postulate that wasted is a mutation in the structural gene for adenosine deaminase. In man, the autosomal recessive form of severe combined immunodeficiency is associated, in about one-third of cases, with a deficiency of adenosine deaminase. Wasted mice are immunodeficient, develop neurological abnormalities, and die soon after weaning. These features are shared with the human syndrome. We therefore further suggest that the wasted mouse is an animal model for this form of severe combined immunodeficiency that will have potential use in gene-therapy studies.

Adenosine Deaminase↗
PubMed1986

Radiation and haematopoiesis in Harwell steel mice.

Haematological information on steel (Sl) mice is limited largely to Sl/Sld mice of Bar Harbor stock (WC.B6 F1). Therefore, two Harwell alleles, SlgbH and Slcon, were investigated. In the steady state both heterozygotes were modestly anaemic, homozygous Slcon and compound Slcon/SlgbH more so. On perturbation by X-irradiation Slcon/SlgbH showed a decrease in median lethal dose (MLD)--6.5 Gy, Slcon/+ and Slcon/Slcon slightly less change (7.5 Gy) compared with +/+, 8 Gy. In recovery from sublethal doses single heterozygotes, double heterozygotes with Wv, and compounds showed no delay in restoration of the count of red blood corpuscles (RBC) such as that seen in typical W mice (e.g. Wv/+, W/Wv). Effects on Slcon/Slcon and Slcon/SlgbH differ from those reported for Sl/Sld in that they show normal growth of spleen colonies when used as lethally irradiated recipients of bone marrow, they support growth of implanted bone marrow to form radiation chimaeras. When Harwell steel mice are donors of bone marrow to lethally irradiated +/+ mice the chimaeras ultimately are not anaemic; when lethally irradiated Harwell steel mice are recipients of +/+ marrow they remain macrocytically anaemic. One deduces that, for normal development and production of normal RBC in the steady state, the erythron requires intrinsic factors determined by wild type alleles at the W locus and extrinsic factors determined by wild type alleles at the Sl locus. Mutant alleles at either locus may determine macrocytosis. Two mutant alleles at either locus are still more deleterious, often lethal. Whereas mutant W alleles may also influence the pluripotent haematopoietic stem cell (HSC) leading to reduced MLD on X-irradiation, a similarly reduced MLD for Sl mutants may represent an increased need for and consumption of products of the haematopoietic stem cells rather than truly increased radiosensitivity, since the Do for spleen colony-forming units is the same for Slcon/SlgbH as +/+ mice.

Animals↗
PubMed1986

Molecular cloning, expression, and characterization of the gene for the surface (HPI)-layer protein of Deinococcus radiodurans in Escherichia coli.

The HPI protein of Deinococcus radiodurans belongs to the class of surface layer proteins which form crystalline two-dimensional arrays on bacterial cell envelopes. We have cloned and expressed the gene for this protein of Mr about 100,000 by using plasmid pUC8 in Escherichia coli. As judged by immunoreaction with monospecific antibodies, apparent Mr, and limited proteolysis, a single clone contained the gene encoding the complete polypeptide on an 8.9-kilobase (kb) insert. The insert was reduced to a 5.7-kb HindIII fragment, cloned in pUC18 in both orientations, and subjected to unilateral processive deletion with exonuclease III. The library of deletion derivatives was mapped and, in conjunction with protein immunoblotting of expressed polypeptides, was used to locate the positions of the structural gene and the Deinococcus promoter region that was responsible for expression of the HPI polypeptide. The HPI gene was confined to a stretch 2.95 kb in length.

Bacterial Proteins↗
PubMed1986

Cerebrospinal fluid studies of monoamine metabolism in schizophrenia.

The authors review the studies of spinal fluid monoamines and their metabolites with and without probenecid and during drug-free and medicated conditions. Although technical knowhow and understanding of the variable that influence the actual levels measured has dramatically increased over the last 20 years, many questions still remain. Despite or rather because of advances such as CT, PET, and MRI, CSF studies still carry great promise for understanding the illness, predicting drug response, and behavioral change following drug withdrawal.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

Differential diagnosis between mesotheliomas and metastatic adenocarcinomas using monoclonal antibodies against gastrointestinal carcinoma antigen and stage-specific embryonic antigen.

Monoclonal antibodies made against gastrointestinal carcinoma antigen (GICA) and stage specific embryonic antigen (SSEA) were evaluated for their ability to distinguish normal mesothelial cells present in pleural and peritoneal fluids from adenocarcinoma cells in tissue and cytology specimens. The presence of GICA was documented in a high percentage of adenocarcinomas from the gastrointestinal tract (75/98) and in 52% of pulmonary (15/29) and 29% of ovarian (6/21) adenocarcinomas. GICA was found infrequently in breast carcinoma (1/18) and not in mesotheliomas (0/16). A similar pattern of GICA expression was seen in malignant effusions from adenocarcinomas (18/47) and mesotheliomas (0/6). SSEA was found in a high percentage of adenocarcinomas derived from the gastrointestinal tract (47/56) and the lung (26/29). SSEA was detected in breast carcinoma (8/15) more often than GICA. SSEA was detected rarely in mesotheliomas (1/16). Reactivities for epithelial membrane antigen, keratin, carcinoembryonic antigen, GICA and SSEA in adenocarcinoma and mesotheliomas were compared.

Adenocarcinoma↗
PubMed1986

[Value of computed tomography in acute adrenal failure].

Three patients with acute adrenal insufficiency of different causes are presented. In all three cases the adrenals were grossly enlarged and showed additional more specific changes that made a definite CT diagnosis possible in spite of the fact that clinical signs were rather non-specific in two of the three cases.

Acute Disease↗