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Biomedical subjects

A Schmidt

Publications and source records attributed to A Schmidt.

At least 649 records · Page 36Linked to original sources
PubMed1983

Comparison of isocapnic hyperventilation and treadmill exercise in children with exercise-induced asthma.

The degree of post-exercise airway obstruction (Exercise-Induced Asthma (EIA] in 14 children was compared to the degree of airway obstruction following isocapnic hyperventilation. EIA was provoked by 6 min of treadmill running. Isocapnic hyperventilation was performed sitting during 6 min. The total ventilation (Vtot) during the two provocations was identical. The temperature of the inspired air was also identical during the two provocations, and the relative humidity was 40% during treadmill-running and 15% during hyperventilation. The decrease in peak expiratory flow after treadmill-running was 29%. After hyperventilation a fall on 19% was seen. These figures are statistically different. It is concluded that although there is a significant difference in airway obstruction after the two provocations the ventilation is greater importance for EIA than is the work load.

Adolescent↗
PubMed1983

Fractures of the tibia treated by flexible external fixation.

Thirty-four patients with fractures of the tibial diaphyseal shaft were treated by flexible anterior half-frame external fixation. The average time to union in the frame was 12 weeks for a simple closed tibial fracture and 26 weeks for a complex open tibial fracture. Complications included malalignment and loss of initial reduction. Most of the complications could have been avoided if special attention had been paid to technical details of reduction of the fracture and insertion of the pins.

Adult↗
PubMed1982

DNA fragmentation and NAD depletion. Their relation to the turnover of endogenous mono(ADP-ribosyl) and poly(ADP-ribosyl) proteins.

Treatment of Ehrlich ascites tumor cells with the trifunctional alkylating agent 2,3-5-tris(ethyleneimino)benzoquinone-1,4 (triaziquonum) led to rapid fragmentation of DNA and depletion of NAD while poly(ADP-ribose) synthetase activity showed a retarded increase. Poly(ADP-ribosyl) residues in treated cells increased 4- to 30-fold, but transiently, and in a dose-dependent manner, exhibiting the same initial kinetics as the loss of NAD and the appearance of DNA strand breaks when determined by the nucleoid method. Although the amounts of "activated ADP-ribosyl" groups present in the substrate NAD (80 nmol/10(8) cells) exceeded by far basal and triaziquonum-induced poly(ADP-ribosyl) groups (up to 250 pmol/10(8) cells), accelerated formation of the polymer, nevertheless, may explain at least partially the loss of NAD seen under these conditions. Addition of benzamide, a potent inhibitor of poly(ADP-ribose) synthetase, to triaziquonum-treated cells effected an immediate drop of poly(ADP-ribose) to basal values. The data indicate a biphasic decay, the half-life of greater than 85% of the polymeric ADP-ribosyl groups exhibiting a t1/2 less than 1 min under these conditions, while the residual fraction died away with t1/2 approximately 6 min. Treatment with the DNA fragmenting agent also led to a 9-fold increase of nuclear mono(ADP-ribosyl) groups, while cytoplasmic mono(ADP-ribosyl) protein conjugates were not significantly affected. The apparent half-life of nuclear mono (ADP-ribosyl) protein conjugates (8-10 min) at peak elevation was definitely longer than that of poly(ADP-ribosyl) residues. This result is consistent with the interpretation that accumulation of mono(ADP-ribosyl) groups is due to a retarded removal of the primary ADP-ribosyl group from the acceptor protein by a separate mono(ADP-ribosyl) protein glycohydrolase, being the rate-limiting step in the overall turnover of poly(ADP-ribosyl) residues.

ADP Ribose Transferases↗
PubMed1982

A heat-stable protein synthesis initiation factor from wheat germ.

A protein synthesis initiation factor of molecular weight 21,500 has been purified to homogeneity from extracts of wheat germ. The factor, referred to as D2d, is stable to heating for 5 min at 75 degrees C and loses less than 15% of its activity upon a similar treatment at 90 degrees C. In contrast, all other wheat germ protein synthesis factors are inactivated by heating for 5 min at 65 degrees C. Formation of 80 S ribosome . Met-tRNAiMet complexes from 40 S ribosome . Met-tRNAiMet complexes, as measured by the binding of [3H]Met-tRNAiMet, is almost completely dependent upon the presence of component D2d. The shift in sedimentation of the ribosome subunits to the 80 S ribosome region, however, occurs in the absence of factor D2d. Thus, the role of the factor is not to join the ribosomal subunits, but rather to keep the Met-tRNAiMet bound to the ribosome. The formation of 40 S ribosome . Met-tRNAiMet complexes is increased 2-fold by the presence of factor D2d. Fixing this complex with glutaraldehyde results in the binding of more Met-tRNAIMet than a nonfixed incubation in the presence of D2d. These results suggest that the primary interaction with the ribosomal subunit can occur in the absence of factor D2d, but that the presence of the factor stabilizes the ribosome-bound Met-tRNAiMet.

Hot Temperature↗
PubMed1982

[Measures to be taken in burns and scaldings at the site of the accident and in the clinic].

The treatment of severe burns must be individual because age, extent and degree of burned body surface, type of accident, previous and additional damages are variable factors in burn disease. Thus there will be given only guidelines to the treatment at the place of accident and in the clinic. There are recommendations to fluid-, electrolyte- and protein replacement, medication and local treatment depending on the extent and degree of burned area. Monitoring is necessary, it includes controls of vital parameters and laboratory results.

Analgesics↗
PubMed1982

Clinical and cytogenetic spectrum of duplication 3p.

An eight months old child with duplication 3p (p21 leads to 3pter) [karyotype: 46,XX,-6,+t(3;6)(6pter leads to 6q27::3p21 leads to 3pter)] resulting from a maternal balanced translocation (3;6) is described. The major clinical findings include congenital heart defects (several ventricular septal defects, atrial septal defect, patent ductus arteriosus, and double outlet right ventricle), and multiple dysmorphic features, such as brachycephaly, frontal bossing, square shaped face, hypertelorism, epicanthus, short prominent philtrum, and short neck. The motor development is retarded. The size of the duplicated segment of 3p is compared to 12 cases reported in the literature. Although the size of the duplicated segment differs in most of the patients, all show a similar pattern of developmental defects. It appears that the region 3p25 leads to 3pter is responsible for the phenotype of duplication 3p syndrome.

Chromosome Aberrations↗
PubMed1982

Fragile site Xq27 and mental retardation. Clinical and cytogenetic manifestation in heterozygotes and hemizygotes of five kindreds.

Clinical and cytogenetic data of five kindreds with X-linked mental retardation and a methotrexate-inducible fragile site at the distal long arm of the X chromosome fra(X)(q27) are reported; comprising a total of 26 individuals studied cytogenetically, 10 hemizygotes, five obligate heterozygotes, seven facultative heterozygotes, and four normal males, i.e., fathers and brothers of affected hemizygotes. The heterozygotes in two of these sibships show partial phenotypic and/or mental manifestation. Two of them, who are obligate heterozygotes, expressed fra(X)(q27) in 23% and 16% of their metaphases at the ages of 27 and 53 years. In the obligate and facultative heterozygotes, who are mentally normal, the marker X chromosome could not be detected in lymphocyte cultures. We conclude from these findings that the occurrence of fra(X)(q27) might correlate with the phenotypic expression in heterozygotes rather than with the age of the individual.

Adolescent↗
PubMed1982

Ca++-transport across basal-lateral plasma membranes from rat small intestinal epithelial cells.

Basal-lateral plasma membrane vesicles were isolated from rat duodenum and jejunum by a Percoll gradient centrifugation technique. Ca-uptake into and Ca-release from the vesicles was studied by a rapid filtration method. In the absence of Na (K-medium) at a Ca concentration of 0.05 mmol/liter and pH 7.4, addition of 5 mM MgATP stimulated Ca-uptake up to 10-fold as compared to a control without ATP. Since the Ca-ionophore A23187 (2 microgram/ml) prevented the accumulation of Ca above the equilibrium uptake and rapidly released Ca accumulated by the vesicles in the presence of ATP, it is concluded that the ATP-dependent uptake of Ca involves accumulation of Ca inside the vesicles. The ATP-driven Ca-transport comigrates with the (Na +K)-ATPase and dissociates from the marker enzymes for mitochondrial inner membrane, endoplasmic reticulum and brush border membrane. It is not inhibited by 1 microgram/ml oliomycin or 0.1 mmol/liter ruthenium red. Replacing K by Na inhibits ATP-dependent Ca-uptake by 60%. Efflux of Ca from passively preloaded vesicles is strongly temperature sensitive and enhanced by A23187. An inwardly directed Na-gradient stimulates Ca-efflux as compared to a K-gradient. Addition of gramicidin reduces the Na-stimulation of Ca-efflux, indicating direct coupling of Na and Ca fluxes across basal-lateral membranes. The results suggest that basal lateral membranes possess two distinct mechanisms for Ca-transport: a) ATP-driven Ca-transport and b) Na/Ca-exchange.

Animals↗
PubMed1982

[35S]proteoglycan metabolism of arterial smooth muscle cells cultured from normotensive and hypertensive rats.

Arterial smooth muscle cells cultured from normotensive and hypertensive rats incorporated [35S]sulfate into the extracellular and pericellular sulfated proteoglycans and endocytose extracellular [35S]proteoglycans at a significantly higher rate in the phase of logarithmic growth than did nondividing cells. 35S incorporation into proteoglycans was positively correlated with [3H]thymidine incorporation into the cellular TCA-precipitable material. The rates of [35S]proteoglycan synthesis and endocytosis per cell pr day were higher in smooth muscle cells from hypertensive than from normotensive animals, the observed differences being related to a higher average protein content of smooth muscle cells cultured from hypertensive rats as compared with cells of normotensive animals. Gel filtration under dissociative conditions separated the [35S]proteoglycans into high and low molecular weight fractions (A, B) differing in glycosaminoglycan composition and their ability to be endocytosed by smooth muscle cells. The relative proportion of the high molecular weight proteoglycan fraction A decreased continuously from sparse to confluent cell cultures.

Animals↗
PubMed1982

A Thioredoxin-Mediated Activation of Glutamine Synthetase and Glutamate Synthase in Synchronous Chlorella sorokiniana.

The effects of thioredoxin, dithioerythrol, and mixtures of both on enzymes involved in N metabolism of Chlorella sorokiniana have been studied. Glutamine synthetase, inactivated in vivo, was activated 8-fold by thioredoxin and dithioerythrol. By the same treatment, the activity of glutamate synthase was stimulated nearly 4-fold. Thus, two key enzymes of N metabolism were shown to be regulated via thioredoxin. The enzymes of the nitrate reducing system, i.e. nitrate reductase and nitrite reductase, were not affected by thiols. From these results, a model of NO(3) (-) metabolism is put forward which considers the regulating effect of light.

Journal Article↗