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Biomedical subjects

R Koch

Publications and source records attributed to R Koch.

At least 235 records · Page 13Linked to original sources
PubMed1988

Blood phenylalanine levels and intelligence of 10-year-old children with PKU in the National Collaborative Study.

Dietary intakes and blood phenylalanine levels of 125 10-year-old children with PKU are reported. Of those patients, 59 discontinued the special diet at 6 years, 16 discontinued at 8 years, 5 discontinued at 6 years but returned to the diet at 8 1/2 years, and 45 continued the diet to 10 years. Phenylalanine intake was determined by 2-day diet records. Blood phenylalanine concentrations revealed a lack of clear distinction between the diet groups; therefore, regression analysis was performed on the group as a whole. The analyses revealed significant relationships between blood phenylalanine levels from ages 6 to 10 years and each of the cognitive outcome variables, after the influences of parental IQ and the age at which treatment was initiated were controlled for. Intelligence test scores were also related to phenylalanine levels between ages 3 1/2 and 5 1/2 years. The findings suggest that dietary restriction of phenylalanine should continue in patients with PKU through at least 10 years of age.

Child↗
PubMed1988

Trace element status of children with PKU and normal children.

The trace mineral (chromium, copper, iron, selenium, and zinc) status of 10 children (4 to 13.8 years) with phenylketonuria (PKU) and 9 normal children (6.5 to 15.9 years) was assessed. The children with PKU were treated with a phenylalanine-free L-amino acid mix that supplied the following percentages (mean +/- standard deviation) of total daily intake: energy, 45 +/- 13; protein, 75 +/- 11; copper (Cu), 62 +/- 10; iron (Fe), 82 +/- 7; selenium (Se), 40 +/- 20; and zinc (Zn) 87 +/- 8. Diet records and blood samples were collected from each subject. Children with PKU had significantly greater mean intakes of Cu, Fe, and Zn than normal children. Mean serum Cu, Fe, and Zn concentrations of the children with PKU and normal children were not different despite significantly greater intakes by the children with PKU. Normal children had a significantly greater mean serum Se concentration and a mean blood chromium concentration 1.6 times that of children with PKU. Individuals whose primary source of protein is an elemental diet are especially at risk for multiple trace mineral deficiencies. Manufacturers of chemically defined medical foods should evaluate composition, specifically molar ratios between minerals, as a basis for product formulation.

Child↗
PubMed1987

Stimulation of breast cancer cells in vitro by the environmental estrogen enterolactone and the phytoestrogen equol.

The phenolic lignans enterolactone and enterodiol appear periodically in women's urine, dependent upon synthesis from plant-derived lignans by the intestinal microflora. The phytoestrogen equol is also present in women's urine, and is also derived from a vegetarian diet. Antiestrogenic or antiproliferative actions of these compounds have been postulated and related to the observation that there is a reduced incidence of breast cancer associated with diet. We evaluated the estrogenic and antiestrogenic activity of these compounds using four sensitive assays in tissue culture, including the use of human breast cancer cell lines T47D and MCF-7. Unexpectedly, we found that enterolactone and enterodiol, as well as equol, are weak estrogens, and that enterolactone and equol could stimulate the growth of estrogen-dependent breast cancer cell lines. We suggest that these environmental agents can promote the growth of breast cancer, particularly hormone-dependent metastases that may be located near the gut or in the mesenteries or liver, where the concentration of these intestinally produced compounds would be highest. Treatment with an antiestrogen such as tamoxifen blocks the estrogenic activity of these compounds. In the absence of treatment with an antiestrogen such as tamoxifen, hormonal therapy to block steroidal estrogen synthesis in a patient with breast cancer could conceivably be circumvented by a vegeterian diet rich in the precursors to estrogenic compounds such as enterolactone and equol.

4-Butyrolactone↗
PubMed1987

Phenylketonuria.

Explore the source record for details and available documents.

Humans↗
PubMed1987

Radioelectroencephalographic comparison of memantine with receptor-specific drugs acting on dopaminergic transmission in freely moving rats.

Chronic implantation of four bipolar concentric electrodes into frontal cortex, hippocampus, striatum and reticular formation allows repetitive recordings of field potentials from freely moving rats. After radiotransmission the EEG signals are submitted to a quantitative spectral power analysis. Drug-induced changes in single frequency bands as obtained from the power spectra from different brain areas lead to a drug-specific pattern which can be compared with those of various standard compounds known to influence dopaminergic transmission in the central nervous system. With regard to receptor specificity the research compounds SK & F 38393 (D-1 agonist), SCH 23390 (D-1 antagonist), quinpirole (D-2 agonist) as well as haloperidol (D-2 antagonist, less specific) are tested under identical conditions. Memantine (1-6 mg/kg, i.p.) induces power decreases in a dose-dependent manner in nearly all frequency bands thus resembling the action of apomorphine. Less similar but still comparable is the action of amphetamine, whereas among the receptor-specific dopaminergic drugs only SK & F 38393 can be regarded as similar in as much as mainly delta, alpha-2 and beta-1 frequencies decrease at the same time. Thus memantine develops its own specific pattern of changes in the EEG which can be used to discriminate it from other drugs. The results are in accordance with the drug's proposed action of enhancing the dopaminergic transmission, which probably implies an indirect mechanism of action as biochemically no direct interaction with any of the dopaminergic receptors has been described for memantine so far.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1987

Generation of oligomeric insulin receptor forms by intramolecular sulfhydryl-disulfide exchange. Involvement of masked sulfhydryl groups.

Insulin receptors from rat liver membranes were labelled with a 125I-labelled photoreactive insulin analogue or by iodination using lactoperoxidase and analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Under nonreducing conditions different receptor forms with Mr 400,000 (alpha 2 beta 2), 360,000 (alpha 2 beta beta'), 330,000 (alpha 2 beta' beta'), 320,000 (alpha 2 beta), 280,000 (alpha 2 beta'), 240,000 (alpha 2), 210,000 (alpha beta), 165,000 (alpha beta') and 115,000 (alpha) were detected. The subunit composition of these receptor forms was determined by two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis in the absence and presence of dithioerythritol. During denaturation in sodium dodecyl sulfate in the absence of reductants, the Mr 400,000 receptor form (alpha 2 beta 2) was converted into the Mr 320,000 (alpha 2 beta) and Mr 240,000 (alpha 2) receptor form. This conversion was prevented either by N-ethylmaleimide, oxidants, or low pH. In contrast, alkylation of the receptor with N-ethylmaleimide under non-denaturing conditions did not prevent the appearance of intermediate-sized receptor forms. Furthermore, the inhibition of receptor cleavage by N-ethylmaleimide during denaturation was also observed when the amount of free sulfhydryl groups was reconstituted by the addition of an unlabelled and non-alkylated receptor sample to the alkylated and photoaffinity-labelled receptor. These results suggest, that the generation of different oligomeric receptor forms detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis is due at least in part to the cleavage of one or both beta-subunits from the insulin receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗
PubMed1987

[Clinical value of ethinyl estradiol sulfonate (Turisteron)--long-term results of a randomized compound study].

In a randomized compound study the therapy effect of ethinylestradiol sulfonate (Turisteron) is tested. As comparative groups serve patients with chemotherapy and Turisteron in combination with chemotherapy. The cumulative 5-year survival rate under the therapy of Turisteron was 61.2%. The comparative groups do not achieve this high survival rate. In connection with the slight stress of the patients (application form, side effects) ethinylestradiol sulfonate (Turisteron) is an effective estrogen in the long-term treatment of the advanced carcinoma of the prostate gland.

Aged↗
PubMed1987

[Prognosis of wound healing].

The knowledge of prognosis of wound healing ist important for the preparation of patients to the operation and for prophylaxis of wound infections. This study on 625 patients demonstrates a method for investigation an objective prognosis. The method allows the selection of patients with a high risk of wound infection.

Humans↗