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Biomedical subjects

T Peters

Publications and source records attributed to T Peters.

At least 235 records · Page 13Linked to original sources
PubMed1986

Pharmacopsychological effects of flunarizine in geriatric patients with light brainorganic psychosyndrome. Preliminary communication.

The effects of the cerebral calcium antagonist flunarizine in 50 geriatric patients with light brainorganic psychosyndrome were determined in the course of a 12 weeks' placebo-controlled pharmacopsychological double-blind study. Factor analysis on the basis of 19 individual psychological tests served as multivariate evaluation model. Advantages of flunarizine became evident in factors 1 (contentedness), 3 (alertness) and 4 (good memory/sound sleep). The increased performance (factor 2) in both groups may well be due to a training effect and would, therefore, be artificial.

Aged↗
PubMed1986

Does father's unemployment put the fetus at risk?

Information concerning 15 037 singleton deliveries in 1970 showed that among the 3.5% where the male head of the household was unemployed there was no significant excess of low birthweight or preterm delivery, once social class had been taken into account. There were major differences, however, in maternal health behaviour. In order to ascertain whether the health behaviour might be a consequence of the unemployment, data were also analysed for the 658 pregnancies in women whose husbands, though employed at delivery, were subsequently unemployed. Almost identical patterns were found, implying that the association with health behaviour was not a time-related consequence of unemployment.

Birth Weight↗
PubMed1985

The biosynthesis of rat transferrin. Evidence for rapid glycosylation, disulfide bond formation, and tertiary folding.

The transit time of newly synthesized transferrin in the liver is markedly longer than that of albumin. We sought to learn the basis of this difference by the use of labeled leucine and mannose in vivo and by isolation of newly formed transferrin from rough microsomes of rat liver. Albumin and alpha 1-antitrypsin, a second glycoprotein, were also studied for comparison. Minimal hepatic transit times were 17, 23, and 31 min for albumin, alpha 1-antitrypsin, and transferrin, respectively. The delay in the case of transferrin was found to occur chiefly in the rough endoplasmic reticulum and to be paralleled by an increase in the amount of transferrin relative to albumin in that organelle. Initial glycosylation of transferrin was as rapid as that of alpha 1-antitrypsin, and essentially all of the transferrin in the rough endoplasmic reticulum contained glycans which bound to concanavalin A and were removed by endoglycosidase H. Only 3% of the transferrin isolated from the rough microsomes came from the plasma by endocytosis or adsorption. Rapidity of disulfide bond formation in rough microsomes was evident from the presence of only 1.3 cysteine thiols/molecule of rough microsomal transferrin (total of 19 cystines) and the absence of mixed disulfides. Peptide patterns upon mild proteolysis were consistent with a native configuration of disulfide bond pairing. The ability of rough microsomal transferrin to bind and deliver iron through interaction with transferrin receptors on reticulocytes suggests that considerable tertiary structure is present. Thus, initial glycosylation, disulfide bridging, and tertiary folding are all rapid processes. The cause for the slow release of transferrin from the rough endoplasmic reticulum may lie with a rate-limiting transfer mechanism.

Animals↗
PubMed1985

Serum albumin.

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Amino Acid Sequence↗
PubMed1985

pH-dependent accumulation of fentanyl, lofentanil and alfentanil by beating guinea pig atria.

The influence of the pH of the incubation medium on the cellular accumulation of tritiated fentanyl, lofentanil, and alfentanil was investigated in isolated guinea pig atria. Fentanyl and lofentanil accumulated in atrial tissue up to about 30- and 50-fold, respectively. The amount of drug bound when equilibrium was attained was found to be dependent upon the pH of the medium. By plotting binding equilibria v. pH of the bath, curves were obtained which resembled titration curves. Half-maximal binding was attained at pH values close to the pKa values of fentanyl and lofentanil. Alfentanil was found to accumulate less. The uptake by the tissue was strongly proportional to the extracellular concentration. Atria equilibrated with fentanyl at pH 8.5 released the compound rapidly when exposed to a pH of 7.0, even in the continuous presence of fentanyl in the bath. The consequences of the findings for in vivo conditions are discussed with respect to a possible augmentation of the actions of fentanyl by respiratory acidosis.

Alfentanil↗
PubMed1985

Stereotactic system and apparatus for use with magnetic resonance imaging, computerized tomography, and digital subtraction imaging.

A light-weight nonmagnetic, nonconductive instrument has been devised for use with magnetic resonance imaging, computerized tomography, and digital subtraction imaging for work in the field of epilepsy, brain tumors and vascular lesions. The apparatus' main characteristic is its ability to use optionally either the lateral orthogonal or the spherical-radial approach.

Brain Neoplasms↗
PubMed1984

Cardiac glycosides with different effects in the heart.

Remarkable differences exist between the effects of different cardiac glycosides (native and semi-synthetic) with respect to the affinity and to the magnitude of inotropic responses and their time courses. At glycoside concentrations which lead to identical Na-K-ATPase inhibitions, the inotropic responses vary widely. This finding contradicts the hypothesis that the increase of contractile force is the consequence of an ATPase inhibition and causally related to it. We propose the hypothesis that the inhibition of ATPase and the inotropic stimulation provoked by cardiac glycosides are two parallel events, not causally related but both mediated by the same receptor. The inhibition of the Na-K-ATPase is the consequence of the occupation and thus proportional to the concentration of the glycoside-ATPase complexes. In contrast, the inotropic response is determined by the frequency of glycoside-ATPase-interactions. Glycosides which possess high association and dissociation rate constants will interact with the ATPase with high frequencies and thus will evoke larger inotropic responses at a given ATPase inhibition than glycosides with low turnover rates.

Animals↗
PubMed1984

Granulocytic cryopreservation: further studies on the pathogenesis of impaired cellular function.

The effects of different methods of purifying peripheral blood granulocytes on their functional capacity after cryopreservation have been studied. The standard method of isolating granulocytes by centrifugation through Lymphoprep sensitizes cells to damage induced by subsequent cryopreservation. Some of this damage occurs during addition of cryoprotectant and we describe how to add and remove dimethyl sulphoxide without impairing cell function. The granulocytic function that suffers most during cryopreservation is granulocyte migration. This impairment may be partially due to uncontrolled entry into the cell of calcium. In contrast the bactericidal capacity in vitro is not so greatly reduced and ability to reduce nitroblue tetrazolium redox dye even less so.

Blood Bactericidal Activity↗
PubMed1983

Immunoregulatory properties of antigenic fragments from bovine serum albumin.

Regulation of the immune response to bovine serum albumin (BSA) by defined substructures of the protein was investigated. The fragments consisted of 41 to 307 amino acids each bearing unique serologic determinants. When administered intravenously the fragments were capable of suppressing the immune response to the entire BSA molecule. The suppression was T-cell mediated and affected the determinants that were linked. The fragments also primed for a secondary anti-BSA response when given in adjuvant; however, the ability to prime was restricted to determinants on the immunizing fragment. The data demonstrate that immune responses to a large protein molecule can be regulated by a relatively small component of its structure and that the ability of a fragment to induce help is more restricted than is its suppressive potential.

Amino Acids↗
PubMed1983

Preparation of fragments 505-582 and 505-573 of bovine serum albumin.

Peptic fragment 505-582 of bovine serum albumin, the "Phe" fragment, has been found useful in several laboratories for studies of antigenic sites, ligand binding and metabolism. It contains the entire carboxyterminal loop, Loop 9, of the albumin molecule. We present an improved preparation of this peptide. Peptide 505-582 is obtained in about 9% yield, along with a similar yield of the closely associated peptide 505-573 arising from a second peptic cleavage. The unusual ultraviolet absorption spectrum of these peptides shows triple maxima near 259 nm reflective of the high phenylalanine content and the total absence of tyrosine and tryptophan.

Amino Acids↗
PubMed1983

Chronic alcohol excess is associated with selective but reversible injury to type 2B muscle fibres.

Patients drinking more than 100 g alcohol/day for longer than three years develop atrophy of striated muscle fibres. This predominantly affects type 2B fibres which are dependent on anaerobic glycolytic metabolism. Atrophy of type 1 and type 2A fibres, which in addition use aerobic mitochondrial respiration, only occurs in the most severe cases and then only to a lesser degree. Abstention from alcohol reverses the changes in muscle which slowly return to normal. Selective injury to type 2B fibres indicates that search should be made for an alcohol-induced biochemical lesion affecting the anaerobic glycolytic pathways of the muscle fibre.

Adult↗
PubMed1983

Stereotactic systems and procedures for depth electrode placement: technical aspects.

The authors describe the conversion of the Leksell spherical system to that of the orthogonal approach for depth electrode placement, by the addition of relatively simple devices to the main frame. These modifications have created the need for new instrumentation such as teleradiology with laser beam centering and the use of an all-purpose stereotactic chair. The main device used for the orthogonal approach is an instrument and electrode carrier moving on sliding side bars. This system can also take advantage of the newer imaging techniques, such as CT scanning, digital angiography and NMR, by the addition of computer markers which are interchangeable with the frame side bars.

Brain Mapping↗
PubMed1982

The biosynthesis of rat serum albumin. In vivo studies on the formation of the disulfide bonds.

In order to learn at what stage the disulfide bonds of albumin are formed during its biosynthesis, we perfused rat livers with iodoacetamide and then isolated the intracellular precursor, proalbumin, from organelles known to be in the pathway of albumin synthesis and secretion. The alkylated cysteines in proalbumin were determined as a measure of its thiol groups in vivo. Proalbumin of smooth microsomes was found to contain a single thiol, which is proposed to be the noncoupling cysteine occurring residue 34 in circulating albumin. Proalbumin in rough microsomes contained an average of two cysteines; the additional cysteine thiol was largely situated in the COOH-terminal region and disappeared rapidly after blocking albumin synthesis with cycloheximide. In nascent chains of proalbumin, about 45% of the cysteine + cystine was in the thiol form. From these findings we propose that disulfide bond formation begins while the nascent chain is still attached to the ribosome and proceeds in an NH2 to COOH direction. The disulfide bonding apparently is completed into the endoplasmic reticulum. Possible intermediates in the process such as mixed disulfide forms of proalbumin with glutathione or cystamine were not detected. We suggest that cysteine-34 does not participate in disulfide bonding because the NH2 terminus of proalbumin remains loosely bound to the membrane, attached by a hydrophobic segment of the chain at residues 21-27.

Animals↗