Biomedical subjects
Publications and source records attributed to G Richter.
The development of the carbon tip electrode and its low chronic threshold behavior are described. Compared to presently used electrode material, carbon tip electrodes result in lower chronic stimulation thresholds. In a group of 43 patients, chronic pulse generator output has been favorably reduced in association with this type of electrode. Thus the use of activated carbon tip electrodes may result in the routine implantation of low output pacemakers.
After a brief review of previous investigations into the antidepressant effect of sleep withdrawal, attention is drawn to problems arising from simultaneous treatment with antidepressants. A method for recording the effects of sleep withdrawal alone is also described. The results indicate that treatment by partial withdrawal of sleep during the second half of the night, tends to have a positive effect on the symptoms of depression and on the psychophysical status of the patients. The author concludes with an overview of the problems still outstanding.
Does mild brain damage sustained during early childhood represent a predisposition to particular forms of abnormal mental and/or social development during early adulthood? Selected results yielded by a longitudinal study on 96 former patients who had been diagnosed as suffering from slight brain damage sustained during early childhood are presented. The psychological aspects (intelligence and concentration) and sociological aspects (formal and vocational education, criminality) investigated were found to have been determined to a decisive degree by milieu and social factors. The results are discussed in the theoretical context provided by the acquisition concept with a view to therapeutic considerations.
27 patients with chronic renal failure, 21 patients on chronic intermittent dialysis treatment and 27 healthy controls were tested for serum level of vitamin E estimated spectrophotometrically. Both patient groups had significant higher mean values (12.1 +/- 1.2 and 7.2 +/- 0.8 micrograms/ml respectively) in comparison with normal controls 4.6 +/- 0.7 micrograms/ml). No correlation was found to serum creatinine, hematologic values, protein and lipoprotein concentration, nor to mode and duration of treatment regimes. Vitamin E was not extracted from blood throughout dialysis. Under normal conditions of conservative or dialysis treatment of chronic renal failure patients vitamin E seems not to be a factor concerning uremic symptoms and there is no need for supplementation.
The apparent digestibility of crude nutrients and the amino acids in the varieties Fribo and Erfordia of horse bean (Vicia faba L.) was determined in a digestibility and N-balance experiment with 32 colostomised laying hen hybrids. For this purpose 4 rations each with a rising quota of horse beans (10%, 20%, 40%, 50%) were tested with 4 hens each in a 6-day collecting period; the digestibility values were determined according to the regressive method. The average apparent digestibility is (formula; see text) The values of the apparent digestibility of the 17 amino acids vary for the variety Fribo between 68.6% (methionine) and 90.6% (arginine) and for the variety Erfordia between 47.7% (cystine) and 89.5% (arginine).
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Transfection by DNA isolated from bacteriophage T3 was studied using Escherichia coli 921/0 as host. The following conditions were found optimal: Competent E. coli 921/0 were obtained by harvesting the bacteria at the onset of late exponential growth (5 X 10(8) cells/ml) and treating the latter with 0.05 M CaCl2. Hereafter, the microbes were suspended in 50 mM Tris-HCl buffer (pH 7.2) and the concentration adjusted to 7 X 10(9) cells/ml. T3 DNA was added and the suspension kept at 0 degrees C for 15 min. Determination of the number of infectious centers was then carried out in the usual way. The efficiency of transfection under these conditions amounted to 10(4) p. f. u./microgram DNA. Preincubation of competent bacteria with T4 DNA at 0 degrees C before the addition of T3 DNA reduced the number of infectious centers. However, if T3- and T4 DNA were added simultaneously no decrease of the transfection efficiency occurred. Calf thymus DNA was without influence on transfection.
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