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Biomedical subjects

M Schmidt

Publications and source records attributed to M Schmidt.

At least 811 records · Page 45Linked to original sources
PubMed1985

Alterations of serum carboxypeptidases N and angiotensin-I-converting enzyme in malignant diseases.

The activities of serum carboxypeptidases N (E.C. 3.4.17.3) and serum angiotensin-I-converting enzyme (E.C. 3.4.15.1) were spectrophotometrically measured in patients with hematological disorders and in histologically proven bronchogenic carcinomas. The enzyme activities have been compared with various laboratory parameters. Controls were healthy subjects. No significant sex differences of carboxypeptidases N and angiotensin-I-converting enzyme were found in the healthy controls or in the whole patients' group. The carboxypeptidases N were significantly elevated in patients with lung cancer (p less than 0.0001) compared to the healthy controls. The angiotensin-I-converting enzyme was significantly reduced (p less than 0.0001) in serum of patients with bronchogenic carcinoma. In responders to chemo- and/or radiotherapy, the carboxypeptidases decreased and the angiotensin-I-converting enzyme increased to normal enzyme values. In non-responders to these therapies no change in these enzymes could be observed.

Adenocarcinoma↗
PubMed1985

[Experiences with selection criteria in myelomeningocele surgery].

Between 1972 und 1983 85 children with myelomeningocele were treated according to the criteria for selective treatment as given by Lorber. The results of children with early or delayed operation and of those who had only supportive care are presented. Survival time and causes of death in the group of children not operated on are in particular given, the sequelae of selective treatment are discussed.

Cerebrospinal Fluid Shunts↗
PubMed1985

Incomplete X chromosome dosage compensation in chorionic villi of human placenta.

Studies of glucose-6-phosphate dehydrogenase (G6PD) in heterozygous cells from chorionic villi of five fetal and one newborn placenta show that the locus on the allocyclic X is expressed in many cells of this trophectoderm derivative. Heterodimers were present in clonal populations of cells with normal diploid karyotype and a late replicating X chromosome. The expression of the two X chromosomes was unequal, based on ratios of homodimers and heterodimers in clones. Studies of DNA, digested with Hpa II and probed with cloned genomic G6PD sequences, indicate that expression of the locus in chorionic villi is associated with hypomethylation of 3' CpG clusters. These findings suggest that dosage compensation, at least at the G6PD locus, has not been well established or maintained (or both) in placental tissue. Furthermore, the active X chromosome in these human cells of trophoblastic origin can be either the paternal or maternal one; therefore, paternal X inactivation in extraembryonic lineages is not an essential feature of mammalian X dosage compensation.

Cells, Cultured↗
PubMed1985

Loop diuretics bind to distinct receptors in renal medulla and cortex.

Receptors which bind [3H]-piretanide were demonstrated on membranes prepared from renal medulla and cortex. They exhibit all the characteristics of a specific receptor such as high affinity, specificity, tissue selectivity, reversible binding kinetics and proportionality between affinity and diuretic effect. Medullary and cortical receptors are clearly distinct since they have different ion requirements.

Animals↗
PubMed1985

Kidney function during arterial chemoreceptor stimulation. III. Long-lasting inhibition of renal tubular sodium reabsorption due to pharmacologic stimulation of the peripheral arterial chemoreceptors with almitrine bismesylate.

The reactions of the mean systemic arterial blood pressure, arterial acid-base balance kidney function (clearance-technique), and plasma aldosterone concentration (radio-immunoassay) elicited by stimulation of the peripheral arterial chemoreceptors with almitrine bismesylate were determined in chloralosed, non-vagotomized, spontaneously breathing cats in moderate mannitol-saline diuresis. The left renal nerves were cut; urine was collected separately from both the innervated and denervated kidneys. Intravenous injection of 0.2 mg/kg of the drug caused the expected long-lasting increase of the pO2 and pH and a decrease of pCO2 in the arterial blood, whereas the mean systemic arterial blood pressure slightly rose by an average of 2-4 mm Hg in the first hour of chemoreceptor stimulation but afterwards considerably decreased below the pre-injection values. The renal responses were characterized by a moderate vasoconstriction particularly in the innervated kidneys and a pronounced increase of sodium and urine excretion especially in the denervated kidneys. The inhibition of renal tubular sodium reabsorption underlying these natriuretic and diuretic reactions was fully demonstrable even at the end of the experiments, i. e. 4 h after the administration of the agent. Plasma aldosterone increased with the time of the experiments but did not show any clear relationships to the activity of the arterial chemoreceptors. The results show that the intravenous injection of almitrine bismesylate is connected with a renal response pattern which is typical for an excitation of the peripheral arterial chemoreceptors, i. e. moderate vasoconstriction (efferently mediated by the renal nerves) and an inhibition of renal tubular sodium reabsorption (efferently mediated by hormonal mechanisms). Furthermore, the data suggest that, on the one hand, under certain conditions these reactions of the kidney function could play the role of undesirable side effects but, on the other hand, the inhibition of renal tubular sodium reabsorption caused by almitrine bismesylate might possibly be used to treat diseases that are connected with a reduced ability of the kidneys to sufficiently excrete sodium.

Aldosterone↗
PubMed1985

[Stress-inducible functional laryngospasm: differential diagnostic considerations for bronchial asthma].

Since 1974 about 30 cases of functional upper airway obstruction are known in literature. We report the findings in a 19 year old woman, who was free from any symptoms during rest. During exercise (swimming, jogging) she showed a loud inspiratory stridor, cyanosis, and dyspnoea. We found this stridor was induced by exercise or hyperventilation only (thread mill, CO2 rebreathing), and was caused by paradoxical vocal cord movement (fibreoptic laryngoscopy in local anaesthesia during CO2 rebreathing). All lung function parameters improved after inhalation of ipratropium bromide. We believe that it is important to investigate these patients during stridor attacks and without general anaesthesia. Otherwise it will be impossible, to get a correct diagnosis.

Adult↗
PubMed1985

Kidney function during common carotid artery occlusion in anaesthetized cats: influence of vagotomy, constant ventilation, blood pressure stabilization, and carotid body chemoreceptor inactivation.

The reactions of kidney function elicited by bilateral common carotid artery occlusion were studied in six groups of chloralosed cats in which the Nn. vagi, the breathing reaction, the increase of the mean systemic arterial blood pressure, and the carotid body chemoreceptors were excluded successively. Carotid occlusion in the control animals caused a rise of the mean systemic arterial blood pressure, hyperventilation, and an increase in renal sodium and water excretion, resulting from an inhibition of tubular reabsorption. Bilateral cervical vagotomy, relaxation and constant artificial ventilation only slightly modified this renal response. Inactivation of the carotid body chemoreceptors in vagotomized and constantly ventilated cats attenuated the natriuresis due to carotid occlusion regardless of the behaviour of the renal perfusion pressure. On the other hand, keeping the mean arterial blood pressure during carotid occlusion constant by the bleeding technique also reduced the natriuretic reaction. Cats with both inactivated carotid body chemoreceptors and constant renal perfusion pressure exhibited an antinatriuretic reaction during carotid clamping. From these data it is concluded that in narcotized cats the natriuretic response during carotid occlusion is the result of both a stimulation of the carotid body chemoreceptors and the rise of the renal perfusion pressure. In contrast, in dogs this so-called carotid-sinus-polyuria seems to be induced solely by the increase of the systemic arterial blood pressure. The findings additionally indicated that the arterial chemoreceptors may be involved in the physiological daily control of renal sodium excretion already at normal arterial oxygen tension under sea-level conditions.

Anesthesia↗
PubMed1985

Kidney function during arterial chemoreceptor stimulation. I. Influence of unilateral renal nerve section, bilateral cervical vagotomy, constant artificial ventilation, and carotid body chemoreceptor inactivation.

The reactions of renal hemodynamics and excretory function elicited by perfusion of the vascularly isolated carotid bodies with venous blood were studied in four groups of chloralosed cats in which the Nn. vagi, the breathing reactions, and the carotid body chemoreceptors were excluded successively. The kidney function was determined using clearance-techniques in both the innervated right and denervated left kidneys. In the animals with intact carotid chemoreceptors perfusion of the carotid bifurcations with venous blood caused a weak (4-6 mm Hg on the average) and transient increase of the mean systemic arterial blood pressure as well as a vasoconstriction and a fall of the blood flow and glomerular filtration rate in the innervated kidneys. In the spontaneously breathing animals carotid body chemoreceptor stimulation effected a rise of fractional sodium excretion only in the denervated kidneys whereas the relaxed and constantly ventilated cats showed a natriuretic response both at the innervated and denervated side. The reactions of renal excretory function did not correlate with those of renal hemodynamics. Vagotomy, relaxation, and constant artificial ventilation failed to abolish the responses elicited by stimulation of the chemoreceptors. Inactivation of the carotid body chemoreceptors by injecting acetic acid into the vascularly isolated carotid sinuses prevented both the hemodynamic and tubular reactions due to hypoxic-hypercapnic perfusion of the carotid bodies. The findings suggest that the arterial chemoreceptors control kidney function by specific reflex mechanisms. The influence of the carotid body chemoreceptors on kidney vasculature is mediated by the efferent renal nerves, whereas the control of renal tubular sodium reabsorption requires hormone action.

Animals↗
PubMed1985

Kidney function during arterial chemoreceptor stimulation. II. Suppression of plasma aldosterone concentration due to hypoxic-hypercapnic perfusion of the carotid bodies in anaesthetized cats.

The reactions of the mean systemic arterial blood pressure, kidney function (clearance technique) and plasma aldosterone concentration (radio-immuno-assay) elicited by perfusion of the vascularly isolated carotid bodies with venous blood were studied in two series of chloralosed, vagotomized, relaxed, and constantly ventilated cats undergoing saline diuresis. In one group of animals the carotid body chemoreceptors were left intact; in the other one, they were abolished by injecting acetic acid into the glomera carotici. In the cats with intact chemoreceptors perfusion of the carotid bodies with venous blood immediately caused a small and transient increase of the blood pressure, whereas renal plasma flow tended to fall despite continuous chemoreceptor stimulation. Renal fractional sodium excretion already increased in the first 25 min of chemoreceptor stimulation, whereas plasma aldosterone concentration showed a significant decrease only after 45 min of venous perfusion of the glomera carotici. Plasma electrolytes changed only little at that time. No clear relationships between the responses of plasma aldosterone and those of the other parameters measured could be obtained. On subsequent perfusion of the carotid bodies with arterial blood plasma aldosterone returned to the values determined before chemoreceptor stimulation. Inactivation of the carotid body chemoreceptors per se already enhanced plasma aldosterone concentration. Perfusion of the glomera carotici with venous blood in the cats with abolished chemoreceptors did not suppress plasma aldosterone content. The data show that plasma aldosterone changes are not involved in the development of the initial phase (first hour) of the inhibition of renal tubular sodium reabsorption provoked by arterial chemoreceptor stimulation, but during long-lasting chemoreceptor stimulation they might contribute to the maintenance of this type of natriuresis. Furthermore the experiments suggest that the decrease of plasma aldosterone repeatedly observed during exposure of mammals to acute hypoxic hypoxia is possibly the reflex result of the stimulation of the arterial chemoreceptors.

Aldosterone↗
PubMed1984

Clinical evaluation of a recombinant hepatitis B vaccine.

Recombinant hepatitis B vaccine prepared from antigen expressed in yeast was given to 30 healthy young volunteers. Seroconversion rates and anti-HBs levels were compared with those in a control group matched for age and sex who had received plasma-derived hepatitis B vaccine. 4 weeks after the third immunisation results were similar in the two groups. In the recombinant vaccine group the immune response developed more slowly during the early phase and seroconversion rates and mean anti-HBs levels were slightly lower in males; this probably reflects use of a lower dose of recombinant vaccine (10 micrograms compared with 20 micrograms of the plasma vaccine). Side-effects were slight and antibody titres against Candida albicans were not increased in recipients of the recombinant vaccine.

Adult↗
PubMed1984

[Focal-segmental glomerulosclerosis in analgesic nephropathy].

The presence and extent of focal-segmental glomerulosclerosis/hyalinosis (FSSH) was determined in 79 autopsy cases of analgesic nephropathy and correlated with the levels of proteinuria, serum creatinine and arterial blood pressure. FSSH was present in 77% of cases. The extent of FSSH correlates positively with increasing proteinuria and serum creatinine. The widely scattered pattern suggests a multifactorial pathogenesis for FSSH in analgesic nephropathy, including, for example, glomerular overload and arterial hypertension. Mesangial proliferative glomerulonephritis was observed in only two cases.

Adult↗
PubMed1984

A case of spurious product formation during attempted resynthesis of proteins by reverse proteolysis. Some batches of 'pure' glycerol contain cross-linking agents.

In cases where enzyme-catalysed synthesis of a peptide bond is being used to re-form a protein from two large peptide fragments, the organic co-solvent chosen has so far been glycerol, for most solvents in use in small-molecule systems are potent protein denaturants. We have found, however, that impurities contaminating certain batches of glycerol are effective in cross-linking the complexes formed by these peptide fragments, thus mimicking the enzyme-catalysed process. In one such case, the reported re-formation of cytochrome c from a two-fragment complex system, cytochrome c-T, the extent and rate of conjugate formation duplicates that reported for enzymic resynthesis. We observed no difference between mixtures containing or lacking enzyme. We warn of the danger of confusion possible to those engaged in studies of resynthesis, and suggest a simple control of purchased glycerol to avoid it. We recommend similar caution to those (X-ray crystallographers and others) who seek to stabilize protein solutions by adding large quantities of glycerol.

Amino Acids↗
PubMed1984

Effect of captopril on intrarenal blood flow.

The inhibition of the renin-angiotensin system by captopril was used in pentobarbital-anesthetized dogs to confirm that the vasoconstrictive action of endorenally synthesized angiotensin II predominates on the efferent glomerular arteriole. Ozolinone is a loop diuretic with two isomers. Only (-)- ozolinone is diuretic, whereas both isomers have a renal vasodilatory effect which predominates on the efferent glomerular arteriole. Only the diuretic isomer increases renin release. The renin hypersecretion is simultaneous with recovery from the initial fall in filtration fraction, because of postglomerular vasodilatation. This recovery does not occur with (+)- ozolinone and is inhibited by pretreatment with captopril. This confirms that vasoconstrictive action of angiotensin II predominates on the efferent glomerular arteriole. Such a vasoconstrictive effect might affect blood flow in the vasa recta, which arise from the efferent arterioles of juxtamedullary glomeruli. This action might enable the renin-angiotensin system to participate in the control of renal medullary blood flow and urinary concentration.

Animals↗