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Biomedical subjects

B Roth

Publications and source records attributed to B Roth.

At least 235 records · Page 13Linked to original sources
PubMed1979

Dihydrofolate reductase from Neisseria sp.

Members of the genus Neisseria are relatively nonsusceptible to trimethoprim, an inhibitor of dihydrofolate reductase. For example, the minimal inhibitory concentration (MIC) of trimethoprim for N. gonorrhoeae ranges from 2 to 70 mug/ml, whereas the MIC for Escherichia coli is 0.2 mug/ml or less. In an effort to understand this difference, dihydrofolate reductase was partially purified from five Neisseria species and compared with the enzyme from E. coli. N. gonorrhoeae dihydrofolate reductase was similar to that from E. coli in molecular weight (18,000) and affinity for the substrates reduced nicotinamide adenine dinucleotide phosphate and dihydrofolate (K(m) = 13 and 8 muM, respectively). However, the gonococcal enzyme had a decreased affinity for trimethoprim, with an apparent K(i) of 45 x 10(-9) M, some 30-fold greater than the E. coli value of 1.2 x 10(-9) M. These enzymes also differed in their isoelectric points and pH activity profiles. Within the genus Neisseria, the dihydrofolate reductase isolated from N. meningitidis and N. lactamica resembled the N. gonorrhoeae enzyme, and only small differences were detected for the N. flavescens and Branhamella catarrhalis dihydrofolate reductases. These data indicate that the relatively poor affinity of trimethoprim for the dihydrofolate reductase from these organisms may be largely responsible for the relative nonsusceptibility of Neisseria sp. to trimethoprim. The contribution of other resistance mechanisms to the overall nonsusceptibility was assessed. Strains of N. gonorrhoeae with altered cell envelope permeability had MIC values less than twofold different from those of isogenic wild-type strains. Also, a direct relationship was observed between the affinity of trimethoprim analogs for gonococcal dihydrofolate reductase and the MIC of these compounds for the gonococcus. These observations suggest that the cell envelope of N. gonorrhoeae is not impermeable to trimethoprim. Changes in the amount of dihydrofolate reductase activity could cause alterations in the susceptibility of the gonococcus to trimethoprim, as demonstrated with N. gonorrhoeae strains selected for trimethoprim resistance after chemical mutagenesis. However, the level of dihydrofolate reductase activity in wild-type N. gonorrhoeae was similar to that of E. coli, indicating that the difference in the susceptibility of these organisms is not due to greater amounts of enzyme in N. gonorrhoeae.

Bacteria↗
PubMed1979

Abnormal gonadothrophin secretion in children with chronic renal failure.

LH and FSH response to intravenous injection of GnRH was evaluated in a group of patients with chronic renal failure on intermittent haemodialysis and in two children with successful renal transplant. Basal plasma LH was elevated in children with chronic renal failure as compared to control, and significantly increased following GnRH injection in most of the children. Basal plasma FSH was higher than in the control group, and slightly increased after GnRH. These data suggest an abnormal response to GnRH in chronic renal failure and an involvement of hypothalamus and pituitary in chronic renal disease. The role of abnormal gonadotrophin secretion in growth retardation and pubertal delay of these children is still not well understood.

Adolescent↗
PubMed1979

[Colonic perforation with special reference to spontaneous ileo-colic perforation].

Aetiology of colonic perforation is reviewed and discussed. 8 cases of "spontaneous" ileo-colic perforations observed between 1975 and 1977 are presented. Two of these patients had recently undergone appendectomy, and 4 others showed a simultaneous distal carcinoma of the large bowel. Histo-pathological evaluation did not reveal the cause of intestinal perforation. Operative treatment and results are given.

Adolescent↗
PubMed1979

[Diabetes insipidus, diabetes mellitus, optic atrophy and labyrinthine deafness: the DIDMOAD-syndrome (author's transl)].

The DIDMOAD syndrome is a combination of diabetes mellitus, diabetes insipidus, optic atrophy and labyrinthine deafness. The inheritance is autosomalrecessive. Diagnostic and therapeutic possibilities are discussed on the basis of a further case of this pathogenetically not yet clarified disease pattern. Early detection of this syndrome in juvenile diabetics is important for long-term prognosis and genetic family advice.

Child↗
PubMed1978

Some peculiar changes in the pattern of respiration connected with REM sleep. A preliminary report.

In the course of polygraphic studies of night sleep the authors recorded respiration through the right and left nostrils by means of two thermoelements. They observed a peculiar and unexpected phenomenon: during the REM sleep phase of the 3rd sleep cycle of 4 healthy persons with 6 full night recordings, respiration through the left nostril stopped, whereas it increased both in frequency and amplitude through the right nostril. This type of respiration continued until awakening. In 2 patients with narcolepsy-cataplexy and in 2 others with idiopathic hypersomnia (8 nights recorded) the same phenomenon was observed with the difference that respiration disappeared on the right side and was preserved on the left side. Furthermore, these changes occurred earlier than in healthy persons. The above changes could be explained by congestion of the venous plexi of the nose.

Adult↗
PubMed1978

[Enteral absorption of sulfasomidine depending on age (author's transl)].

After intravenous and oral application of 25 mg 6-(sulfanilamido)-2,4-dimethyl-pyrimidine (sulfasomidin)/kg body-weight to 29 newborns, 8 infants and 9 older children the completeness and rate of absorption were determined. Sulfasomidine was completely absorbed in newborns (mean value 95.7%) as well as in older children (mean value 94.4%). Concerning the rate of absorption there were age-dependent differences. Using the Bateman function for the kinetic model of intestinal absorption the rate constant of invasion k1 was significantly lower in the first week of life compared to that in older children. In agreement with these data the time tmax of the maximum serum concentration was significantly prolonged in newborns compared to that of older children.

Administration, Oral↗
PubMed1978

[Experiences with percutaneous K-wire osteosynthesis in distal radius fractures].

Follow-up controls were made on 300 patients whose fractures of the distal radius were treated by a primary operative fixation with percutaneous K-wire. This group showed significantly better results than a control group of 300 patients given conservative management. We recommend a primary percutaneous K-wire osteosynthesis as treatment of choice for the management of distal radius fractures.

Adolescent↗
PubMed1977

[Comparative chromatographic analyses of s-triazines (author's transl)].

The applicabilities of gas chromatography (GC), high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) for residue analysis of s-triazine herbicides are compared. With the conditions discussed the detection limit for the 14 s-triazines was determined as follows: 0.02-0.03 ng in GC alkali flame-ionization detection, 0.8 ng in GC flame-ionization detection, 1 ng in HPLC (UV detection), 3-5 ng in HPTLC (UV detection) and 8-13 ng in TLC (UV detection). The linear range in GC (AFID) was 10(4) whereas in the three liquid chromatographic methods it was 10(2). The reproducibility with a confidence limit of P = 95% had a coefficient of variation of +/- 5%. In routine analysis requiring a large number of separations HPTLC has advantages, because the time for a single separation is only 40 sec.

Chromatography↗
PubMed1977

[Indocyanine green kinetics in newborns with non-hemolytic hyperbilirubinemia (author's transl)].

The kinetic parameters of indocyanine green elimination from blood were determined after an intravenous load of the dye in a dosage of 2-4 mg per kg body weight in 22 newborns with a non-hemolytic hyperbilirubinemia. Since the uptake of indocyanine green by liver is selectively carried out and the dye is not further metabolised, these kinetic parameters serve as measures for the performance of hepatocellular elimination. 11 of these newborns were treated 5 days previously with 7.5 mg phenobarbital per kg body weight. Compared to the untreated group, the serum bilirubin concentration significantly decreased after treatment with phenobarbital and the parameters of elimination of the dye from blood changed as described by saturation-kinetics. The maximal elimination-rate Vmax and the Michaelis-Menten-constant Km were significantly higher in newborns treated with phenobarbital (71.1 muMol/l-min and 356.4 muMol/l) than in the untreated ones (23.4 muMol/l-min and 100.0 mutmol/l). Kinetic data of indocyanine green elimination gathered in newborns treated with and without phenobarbital support the hypothesis that cytoplasmatic proteins oliver should facilitate the uptake of organic anions inclusively bilirubin into the liver cell. A defiency of such transport proteins may be one of the causes of non-hemolytic hyperbilirubinemia in newborns.

Female↗
PubMed1977

The age-dependence of intestinal absorption using d-xylose as an example.

In 40 infants the serum concentrations of D-xylose were measured from capillary blood samples up to 300 min after an oral dosage of 0.5 g of D-xylose per kg body weight. The parameters of the absorption kinetics, which are calculated by a digital computer program, showed an age-dependent behavior. Infants up to the age of 2 months have lower maximal serum concentrations compared to older ones because of a larger volume of distribution. The rate constant of invasion k1, which serves as a measure for the rate of intestinal absorption and the rate constant of elimination k2 were significantly lower in infants up to the age of 2 months compared to older ones. The quotient of k1:k2 was independent of age. The time it took to reach maximal serum concentration was significantly longer in young infants. By adding metoclopramide simultanously to the oral D-xylose doses it could be demonstrated that the slower motility of the gastrointestinal tract in newborns and young infants is not exclusively responsible for the slower rate of absorption of D-xylose. Comparing the absorption rates in 26 infants after different D-xylose dosages a saturation kinetics may be supposed.

Age Factors↗
PubMed1977

[Diagnostic procedure in congenital saccharase-deficiency (author's transl)].

The diagnostic procedure is described in a 20 months old infant suffering from hereditary saccharase-deficiency. As a simple and adequate method the kinetic analysis of the oral disaccharide-tolerance-test can be used. The comparison of the areas under the glucose-concentration-curves in blood after the oral monosaccharide (glucose and fructose) and disaccharide (saccharose)-load, can be used as a measure for activity of saccharase in the intestinal mucosa.

Blood Glucose↗
PubMed1977

[Subhepatic abscess after cholecystectomy with coagulation active substance].

4 cases of postoperative subhepatic abscess formation after cholecystectomy are reported, where absorbable hemostatic agents for control of bleeding had been used. The etiology of these complications is discussed. The use of local hemostyptica is strongly disadvised in all possibly bacteriologically contaminated procedures.

Aged↗