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Biomedical subjects

M Schmidt

Publications and source records attributed to M Schmidt.

At least 847 records · Page 47Linked to original sources
PubMed1984

Sustained suppression of voluntary sodium intake of spontaneously hypertensive rats (SHR) in hypobaric hypoxia.

Spontaneously hypertensive rats (SHR) of the Okamoto-Aoki-strain (n = 20) and normotensive rats (NCR) of a random-bred Wistar strain (n = 20) were kept in low-pressure chambers for 13 days at sea-level atmospheric pressure, then for 20 days at a simulated altitude of 4000 m, and subsequently again for 10 days at sea-level. The unrestrained animals were placed singly in metabolic cages and had free access to food, water, and a 2.5% NaC1-solution. Exposure to hypobaric hypoxia led to a transient decrease of daily food and water intake in both strains of animals and a slight reduction of saline consumption in the NCR. In contrast, the SHR showed a massive and sustained suppression of their voluntary intake of hypertonic saline throughout high-altitude exposure. Renal electrolyte and water excretion followed the reactions of salt and water intake. - In an additional series of experiments it was found that SH-rats react with a decrease of their systemic arterial blood pressures in hypobaric hypoxia only on condition that food and water but no additional salt is available to the animals. The data suggest that the antihypertensive effects of chronic high-altitude hypoxia depend both on the availability of salt and a reduction of salt appetite.

Altitude↗
PubMed1984

Influence of age on carotid body size and arterial chemoreceptor reflex effects in spontaneously hypertensive (SHR) and normotensive rats.

In normotensive Wistar rats of a random-bred strain and in spontaneously hypertensive rats (SHR) of the Okamoto-Aoki-strain, the mean systemic arterial blood pressure, the pO2, pCO2, pH-values and the base excess of the arterial blood were measured during ventilating normal air as well as hypoxic (12.6% O2 in N2) and hyperoxic (100% O2) gas mixtures. The animals were anaesthetized and breathed spontaneously; they aged 5-6, 15-20, 30-40, and 50-70 weeks. The volume of their carotid bodies was determined morphometrically. When compared with the age-matched normotensive controls at an age of 5-6 weeks the SHR already exhibited slightly but significantly elevated blood pressures but had equal carotid body size and arterial carbon dioxide tension. In contrast, hypertensive animals in the established phase of hypertension (older than 15 weeks) showed greater carotid bodies and a highly significant respiratory alkalosis when compared with the corresponding age-group of the normotensive rats. The reactions of the mean systemic arterial blood pressure and the arterial pCO2 provoked by hypoxia and hyperoxia proved to be age-dependent in both the normotensive and hypertensive animals but this influence of age was different in the two strains of rats. The data support the concept that alterations of arterial chemoreceptor structures and reflex effects found in the established phase of hypertension are the result of this disease. Furthermore they indicate that, when interpreting arterial chemoreceptor reflex effects in hypertensive humans and animals, the stage of hypertension must be taken into account.

Aging↗
PubMed1984

[Infected joint fracture. Diagnosis, treatment and results in 63 patients].

For diagnosis, treatment and prognosis of infected articular fractures special attention should be paid to the following: When conventional treatment with puncture and irrigation of the joint after a maximum of 7 days is not successful, synovectomy in the early stage of infection, before extensive cartilage destruction particularly in the knee, elbow joint and hand, is the appropriate treatment. The progressive destruction of the cartilage and bone is interrupted. As a result of the early functional after-treatment good mobility of the joint and cartilage nutrition are achieved. In patients who were treated with synovectomy the time for healing was only 4 months, after arthrectomy 7 months and arthrodesis 20 months. Taking into consideration the complaints, mobility and shortening of the leg synovectomies had better results. The overall result demonstrates that despite enormous therapeutic effort, the infection in articular fractures is a serious complication which often leads to permanently functional deficiencies. Of 55 re-examined patients 34 were free of complaints, 5 amputations were necessary as a result of severe neurovascular damage and sepsis. The best results were achieved with early synovectomy.

Adolescent↗
PubMed1983

[Problems in the phlebographic determination of the age of thromboses (correlation of surgical findings in 42 surgically treated thrombotic occlusions of the lower extremities and the pelvic veins with phlebographs].

The diagnostic accuracy of the radiographic signs of acute thrombosis in the lower limbs and pelvis was studied in the phlebograms of 40 patients treated surgically. it was shown that the radiological signs which are said to indicate recent thrombosis (such as the cupola-, contour- and india rubber sign) could be demonstrated in 60% of old clot, i.e. after six days. The reasons for this are discussed.

Adult↗
PubMed1983

Family of middle repetitive DNA sequences in the mouse genome with structural features of solitary retroviral long terminal repeats.

Screening of a 129/J mouse genomic library under nonstringent hybridization conditions with a xenotropic virus-like long terminal repeat (LTR) probe revealed a family of sequences resembling insertion elements (IS) with structural features of solitary retroviral LTRs; these are called LTR-IS. They are interspersed among variable flanking regions of mouse DNA and lack any viral structural genes. LTR-IS elements start and end with 11-base-pair inverted repeats and contain signals implicated in RNA polymerase II transcriptional regulation: C-C-A-A-T, T-A-T-A-A-A, and A-A-T-A-A-A. The members of the family are homologous, but not identical, approximately equal to 500-base-pair-long elements with 4-base-pair target-site duplications on both sites of the element. There are 500 LTR-IS per mouse haploid genome.

Bacteriophage lambda↗
PubMed1983

Temporal sequence and unit composition in dream reports from different stages of sleep.

Mentation reports were collected from 23 subjects following awakenings from REM and NREM sleep and at sleep onset. Subjects organized these reports according to temporal sequence, and judges scored them for activity-based temporal units and for the composition of such units. The judgment data were subjected to analysis to determine whether reports differed systematically by state in either thematic sequencing (moment-to-moment setting and character continuity) or unit composition (density of characterization, setting articulation). Previous findings of inter-state differences in dream quantity (recall, length) were replicated. a sample of typical-length multiunit reports showed a number of stage differences, while samples of matched-length reports did not differ by stage in thematic sequence or the degree of articulation of single units. However, matched for length, REM reports continued to contain more per-unit self representation than did sleep onset reports and denser per-unit overall characterization than NREM reports. The results suggest that most inter-stage differences in dream "quality" are, in fact, by-products of inter-stage differences in dream quantity, but that there are residual stage differences that can coherently be attributed neither to differences in the continuity with which dream production processes are activated in different stages nor to differences in dream retrieval from different stages.

Cognition↗
PubMed1983

[Pharmacologic characteristics of renal dopaminergic receptors: therapeutic perspectives].

The effects of dopamine (DA) on the smooth muscle fibres of the renal vascular bed are complex. They involve the postsynaptic alpha- and beta-adrenoceptors as well as the dopamine ones. On denervated kidney, in presence of alpha- and beta-blockers, intrarenal DA perfusion provokes vasodilation, increases natriuresis and stimulates renin secretion. The vasodilator effect of DA on the renal vascular bed was studied thanks to an isolated perfused rat kidney preparation which, when high concentrations of phenoxybenzamine and sotalol were present, made it possible to measure the effect of dopaminomimetics and dopaminolytics on the renal vascular resistance of a kidney previously vasoconstricted by continuous PGF2 alpha perfusion. (+)--Butaclamol and cis-flupenthixol proved to be invaluable tools to demonstrate the specificity of the dopamino-agonists response, since both shift the dose-response curve according to the criteria for competitive antagonism at doses at which their isomers are not active (fig. 2). Thus, it was possible to calculate the apparent pA2 for the various dopaminolytics and to classify them according to their affinity for the renal vascular dopamine receptors. Table 1 gives the classification. Flupenthixol, which has only a low affinity for the alpha 2-adrenoceptors, already inhibits the vasodilator effect of DA at 10(-8) M. The low stereospecificity of the enantiomers of sulpiride allows a distinction to be drawn between the "postsynaptic" vascular dopamine receptors and the presynaptic ones. The agonists of the renal vascular dopamine receptors provoked dose-dependent renal vasodilation on our preparation when phenoxybenzamine and sotalol were present and this was stereoselectively inhibited by (+)-butaclamol. Table II shows the activity of the dopaminomimetics meeting these criteria. p-Tyramine, di-propyl-m-tyramine and RU 24926 proved to have no dopaminomimetic effect. Their lack of activity seems to be attributable to the suppression of the hydroxyl in position 4. Mesenteric, splenic or cerebral artery preparations were also used to characterize the vascular dopamine receptors : tables III and IV compare the results taken from the literature. The classification obtained tallies quite well which suggests that the dopamine receptors located in the various vascular beds are identical. We compared the characteristics of the renal vascular dopamine receptor established from isolated rat kidney, with three other pharmacological models of dopamine receptor : the activation of dopamine-sensitive adenylate cyclase, the presynaptic modulation of the transmission of the sympathetic influx, and prolactin release (Table V).(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia↗
PubMed1983

Bacterial colonization of newborn infants in an intensive care unit.

Bacterial screening of external ear, umbilical and gastric fluid samples from infants at admission to the intensive care unit yielded opportunistic pathogens in 22% and 12% in the years 1980 and 1982, respectively. As a result of improved hygienic measures and more rational use of antibiotics, bacterial colonization of infants staying longer than 3 days decreased from 56% to 19%. Antibiotic treatment is not indicated if opportunistic pathogens except Streptococcus agalactiae (group B), are cultured from infants without clinical symptoms.

Anti-Bacterial Agents↗
PubMed1983

Clinical studies on teenage Brazilian victims of thalidomide.

Ninety-three Brazilian teenagers with thalidomide embryopathy were studied. The pattern of distribution of their most significant defect was: upper limbs, 66; lower limbs, 8; all four limbs, 12; head, 7. Only 10 individuals presented the major defect unilaterally. In 30 of 83 with bilateral defects there were differences in severity between the two sides. Of the 31 patients whose spines had been X-rayed, 16 showed defects, the most common being spina bifida occulta at S1. Gynecomasty was found in three of the patients having major upper limb defects.

Abnormalities, Drug-Induced↗
PubMed1982

Vasodilator effects of dopaminomimetics in the perfused rat kidney.

The renal vascular effects of dopaminomimetics were studied in the isolated perfused rat kidney after pretreatment with 10(-5) M phenoxybenzamine and 10(-5) M sotalol and after contraction of the vascular bed with prostaglandin F2 alpha (10(-7) to 3 x 10(-6) M). Under these conditions, our criterion for vascular dopaminomimetic activity was renal vasodilation, competitively inhibited by d-butaclamol (10(-8) M) but not by 1-butaclamol (3 x 10(-8) M). Dopamine is active at micromolar concentrations (ED50 = 2.53 +/- 0.34 x 10(-6) M). The N-alkylated analogues of dopamine preserve this activity if the alkyl group is a methyl group (epinine) or two n-propyl groups (di-n-propyl-dopamine). The catechol nucleus appears essential for renal vascular dopaminomimetic activity (SK&F 38393, active; p-tyramine, di-n-propyl-m-tyramine and RU 24926, inactive). Bromocriptine reproduces renal dopaminergic vasodilation with an ED50 of 1.3 +/- 0.14 x 10(-6) M. The study of structure-activity relationships of dopaminomimetics relates the vascular dopamine receptor, associated with renal vasodilation, to the dopamine receptor, associated with stimulation of dopamine-sensitive adenylate cyclase.

Animals↗
PubMed1982

In vitro differentiation of F-9 teratocarcinoma cells does not induce expression of endogenous retroviral glycoprotein.

Undifferentiated F-9 teratocarcinoma cells derived from 129/J mice are induced in vitro to express several differentiation markers. Neither undifferentiated nor differentiated F-9 cells express endogenous retroviral glycoprotein (gp70), although the latter can be productively infected with exogenous retroviruses. This is discussed in context with previous findings that all antigen-activated lymphocytes of all mice express endogenous retroviral gp70.

Animals↗
PubMed1982

Replication variants of the human inactive X chromosome. I. Variability within lymphocytes of single individuals.

The sequence of DNA replication was studied within the inactive X chromosome in human lymphocytes, by means of the FPG method. Several variants of the replication sequence were found. The number of variants in the cells of a single donor exceeded 2 in each of the 4 normal individuals studied. The phenomenon is discussed with respect to the regulation of DNA synthesis and to the cell differentiation process.

Cell Cycle↗