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Biomedical subjects

P Walter

Publications and source records attributed to P Walter.

At least 325 records · Page 18Linked to original sources
PubMed1984

Occlusal splints (MORA) vs. placebos show no difference in strength in symptomatic subjects: double blind/cross-over study.

Many athletes with or without occlusal problems are now using mandibular orthopedic repositioning appliances (MORA) or simply occlusal splints, supposedly to enhance skeletal muscle strength. Recent research to establish these claims has suffered from design inaccuracies. In theory, the MORA reduces temporomandibular stress during clenched jaw efforts. It is suggested that pain in the temporomandibular joint (TMJ) and surrounding musculature could limit a maximum effort during an athletic endeavour. Eight subjects with TMJ disorders were tested for strength changes in 4 muscle groups with a custom MORA and placebo splint in a tightly controlled double-blind cross-over protocol using a Cybex II dynamometer. A two-way analysis of variance (ANOVA) did not show significant differences in strength change between the two splints. Neither were there any trends that would suggest strength benefits from the MORA.

Adult↗
PubMed1984

[The placenta of premature and hypotrophic Gabonese infants].

494 placentae coming from two different geographical parts of Gabon were studied. They were grouped into control, premature, small-for-dates and stillborn. The urban population gives rise to most mothers of about 26 years of age, who deliver normally at 38 weeks of babies weighing 3,300 g and 50 cm long, with placentae weighing 550 g, as well as premature babies and those in which there is white cell infiltration of the membranes, signs of toxaemia and normal placentae. On the eastern plateaux of Gabon there are more mothers around the age of 23, who deliver normally at 37 weeks of pregnancy of babies weighing 3,100 g and 48 cm long, with placentae weighing 450 g, with small-for-dates babies and inflammation of the placenta. Malaria is the cause of many premature deliveries and of small-for-dates and stillborn, especially in the plateaux.

Female↗
PubMed1983

Translocation of a lysosomal enzyme across the microsomal membrane requires signal recognition particle.

Signal recognition particle (SRP), an 11S ribonucleoprotein (Walter and Blobel (1982) Nature 299, 691-698), is required for translocation of secretory proteins across microsomal membranes (Walter and Blobel (1980) Proc. Natl. Acad. Sci. USA 77, 7112-7116) and for asymmetric integration into microsomal membranes of a transmembrane protein (Anderson et al., (1982) J. Cell Biol. 93, 501-506). We demonstrate here that SRP is also required for translocation of the lysosomal protease cathepsin D across microsomal membranes.

Animals↗
PubMed1983

Stereospecific effects of (+)- and (-)-catechin on glycogen metabolism in isolated rat hepatocytes.

(+)- and (-)-catechin showed opposite effects on glycogen metabolism in isolated rat hepatocytes. Addition of 0.5 mM catechin to hepatocytes from fasted rats resulted in the case of the (+)-isomer in a 90% stimulation and the case of the (-)-isomer in a 90% inhibition of net glycogen production. When 0.5 mM of the two isomers were added to hepatocytes from fed rats, (+)-catechin inhibited glycogenolysis by 33%, whereas the (-)-isomer stimulated the same process by 42%. At equal concentrations, the effects of (-)-catechin were stronger than those of the (+)-isomer. (-)-Epicatechin acted in a manner similar to (+)-catechin; however, the effect was less pronounced. (+)-Catechin antagonized the inhibitory action of suboptimal doses of glucagon on glycogen production whereby no change in basal or glucagon-elevated cyclic AMP level was observed. The activities of glycogen synthase a and glycogen phosphorylase a were changed by (+)- and (-)-catechin in a way corresponding to the changes in glycogen production and breakdown. (-)-Catechin, however, stimulated the activities of both glycogen synthase a and glycogen phosphorylase a in hepatocytes from fed rats. A possible interaction of the flavonoids or of their metabolites with glycogen phosphorylase is discussed.

Animals↗
PubMed1983

Disassembly and reconstitution of signal recognition particle.

Signal recognition particle (SRP) is a ribonucleoprotein consisting of six distinct polypeptides and one molecule of small cytoplasmic 7SL-RNA. The particle was previously shown to function in protein translocation across, and protein integration into, the endoplasmic reticulum membrane. A rapid procedure was developed to disassemble SRP into native protein and RNA components. The method utilizes unfolding of SRP with EDTA and dissociation on polycationic matrixes. SRP proteins prepared this way sediment below 7S and are inactive in activity assays. When recombined with 7SL-RNA in the presence of magnesium, the proteins are shown to reassociate stoichiometrically with 7SL-RNA to form fully active 11S SRP.

Animals↗
PubMed1983

Primary structure of the Saccharomyces cerevisiae gene for methionyl-tRNA synthetase.

The sequence of a 5-kilobase DNA insert containing the structural gene for yeast cytoplasmic methionyl-tRNA synthetase has been determined and a unique open reading frame of 2,253 nucleotides encoding a polypeptide chain of 751 amino acids (Mr, 85,500) has been characterized. The data obtained on the purified enzyme (subunit size, amino acid composition, and COOH-terminal sequence) are consistent with the gene structure. The protein sequence deduced from the nucleotide sequence reveals no obvious internal repeats. This protein sequence shows a high degree of homology with that of Escherichia coli methionyl-tRNA synthetase within a region that forms the putative methionyl adenylate binding site. This strongly suggests that both proteins derive from a common ancestor.

Amino Acid Sequence↗
PubMed1983

Subcellular distribution of signal recognition particle and 7SL-RNA determined with polypeptide-specific antibodies and complementary DNA probe.

Signal recognition particle (SRP) is a ribonucleoprotein consisting of six distinct polypeptides and one molecule of small cytoplasmic 7SL-RNA. The particle was previously shown to function in protein translocation across and protein integration into the endoplasmic reticulum membrane. Polypeptide specific antibodies were raised in rabbits against the 72,000-, 68,000-, and 54,000-mol-wt polypeptide of SRP. All three antibodies are shown to neutralize SRP activity in vitro. A solid phase radioimmune assay is described and used to follow SRP in various cell fractions. The partitioning of SRP is shown to be dependent on the ionic conditions of the fractionation. Under conditions approximating physiological ionic strength, SRP is found to be about equally distributed between a membrane associated (38%) and a free (15%) or ribosome associated (47%) state. Furthermore, it is shown that greater than 75% of the total cellular 7SL-RNA is associated with SRP polypeptide in these fractions. Thus it is likely that the major--if not the only--cellular function of 7SL-RNA is as a part of SRP.

Animals↗
PubMed1983

[Peripheral arterial occlusive disease of the lower extremities].

Disturbance of the arterial perfusion of the lower limbs with occlusion in the aorto-iliac area presents a broad field of operative treatment in younger patients below 70 years of age. In older people caution is necessary depending on preexisting multiple morbidity. If necessary, extra-anatomic bypass operations have to be taken into consideration in order to save a jeopardized leg. Limb salvage should be accomplished whenever possible. In case of involvement of the femoro-popliteal region even in old age patients aggressive surgery for limb salvage is important because of high mortality due to primary amputation and last not least because of better life quality and for cardiovascular training. Conservative treatment of occlusions in the aorto-iliac area is not promising much success. Therefore in this area vascular surgery is the treatment of choice. In contrary arterial occlusion of the femoro-popliteocrural region--especially if both are combined--can be positively influenced by conservative angiological regimen. Hence conservative therapy should always be tried first, before difficult and long lasting vascular reconstructions are taken into consideration. One should not forget that surgery of occlusive vascular disease is only a symptomatic therapy, not a curative one. Life expectancy is not enhanced, but only ability of walking is saved. Generally spoken, the patient with occlusive vascular disease of the lower limbs nowadays can be offered a differentiated and individualized therapy including, also, non-surgical procedures. Well planned reconstructive vascular surgery has a good long time prognosis saving the physical integrity and efficiency of the older patient suffering from disabling vascular alterations.

Aged↗
PubMed1983

[Alfentanil, a new, short-acting opioid. Hemodynamic and respiratory aspects].

The haemodynamic and respiratory-depressive effects of 20 micrograms/kg and 40 micrograms/kg of alfentanil in 54 patients with coronary bypass operation were compared with a control group (n = 36). The measurements were carried out at 3 different times, each lasting over a 10 min period: 1. Before induction of anaesthesia but after premedication with flunitrazepam. 2. During anaesthesia and 3. during extracorporeal circulation (standardized conditions).--The preoperative as well as the intraoperative investigations showed a reduction in pulse rate, mean arterial pressure, left ventricular pressure and arterial perfusion pressure during extracorporeal circulation. As cardiac output remained constant in the awake patient, peripheral vasodilatation was predominant. Aside from this during anaesthesia reduction in cardiac output may have been responsible for the decrease in pressure although the cause of this could be the nitrous oxide as well. During the preoperative period a clear increase in wedge pressure, mean pulmonary artery pressure, right atrial pressure and pulmonary vascular resistance occurred from the 3rd minute after the injection. The cause is a vasoconstriction during apnoea. In the intraoperative period this did not occur. The respiratory depression(paO2: -34%, paCO2: +29%) resembles that after fentanyl, except that it starts earlier and lasts for a shorter time. In summary, it can be stated that all effects after alfentanil are similar to those of fentanyl.

Adult↗
PubMed1982

The protein translocation machinery of the endoplasmic reticulum.

The rough endoplasmic reticulum (r.e.r.) has been postulated to possess a single translation-coupled translocation system (in multiple copies) that effects signal sequence-mediated translocation of all secretory and lysosomal proteins and integration of all integral membrane proteins whose port of entry is the rough endoplasmic reticulum (G. Blobel 1980 Proc. natn. Acad. Sci. U.S.A. 77, 1496-1500). Two proteins have been isolated that are components of the r.e.r. translocation system. Their properties and function in protein translocation across and integration into membranes are discussed.

Animals↗