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Biomedical subjects

G W Schmidt

Publications and source records attributed to G W Schmidt.

53 records · Page 3Linked to original sources
PubMed1978

Post-translational transport into intact chloroplasts of a precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase.

A precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase [3-phospho-D-glycerate carboxylyase (dimerizing), EC 4.1.1.39] has been identified among the products of cell-free translation of polyadenylated RNA from spinach and pea. In both cases, the precursor is larger than the mature protein by 4000-5000 daltons. Upon incubation of post-ribosomal supernatants of the in vitro protein synthesis mixtures with purified intact chloroplasts, the pea and spinach precursors are transported interchangeably into the chloroplasts and processed to the mature size and charge. Moreover, the newly transported small subunits are found to assemble with endogenous large subunits to form the holoenzyme. In contrast, a precursor to the Chlamydomonas reinhardtii small subunit is not taken up by higher plant chloroplasts, indicating the specificity of the transport events. Together, these results demonstrate that the in vitro reconstruction of the post-translational transport of the higher plant precursors is physiologically significant.

Journal Article↗
PubMed1977

[The optimal protein quantity in infant nutrition].

Nowadays, the trend of recommendations to prepare infant formulas with only 2 per cent or less of protein does not correspond with the optimal protein demand and protein utilization in infants. Such formulas often prompt mothers to add carbohydrates to the protein half-strength milks in order to satisfy the infant's hunger. This often leads to the unwanted effect to obesity. There is no evidence to prove that infants above the age of 1 month should not receive 2.2 or 2.3% of protein in their formulas. This quantity is fully utilized by the infants; it has no disadvantages and is safe. Hence, the recommendations should not be based on the minimum daily requirements but on the optimal utilization, whereby the tendency to obesity can also be reduced.

Amino Acids↗
PubMed1977

A rapid procedure for selective enrichment of photosynthetic electron transport mutants.

Metronidazole (2-methyl-5-nitroimidazole-l-ethanol) is shown to be effective for the selective enrichment of mutants of Chlamydomonas reinhardtii that posses impaired photosynthetic electron transport. More than 99.9% of wild-type cells are killed when incubated in the presence of 6-10 mM metronidazole for 24 hr under illumination of 7500 lux. Survival of wild-type cells in darkness and of mutants that are blocked at different steps in photosynthetic electron transport is nearly 100% when incubated in the presence of the drug under identical conditions. The toxicity of metronidazole is demonstrated to depend upon its reduction by photosynthetic electron transport. Light-dependent oxygen uptake mediated by metronidazole is shown to require active photosystem l in vitro and in vivo. Ferredoxin is necessary for metronidazole reduction by thylakoid membrane fractions enriched in photosystem l activity. We propose that the toxicity of metronidazole is due to the formation of lethal derivatives of the drug or to the accumulation of hydrogen peroxide, which could occur upon autooxidation of metronidazole reduced by one electron. The results indicate that mutants of C. reinhardtii, and probably other photosynthetic organisms, with any lesion in photosynthetic electron transport from the oxidizing side of photosystem ll to ferredoxin can be isolated by metronidazole treatment of mutagenized cultures.

Cell Membrane↗
PubMed1975

[Detection of a hitherto unknown ninhydrin positive substance in the haemolysate of patients with metachromatic leucodystrophy (author's transl)].

A hitherto unknown substance, which appears between glycine and alanine in ion exchange chromatograms, was found in the erythrocyte cold haemolysate of two children with metachromatic leucodystophy; this substance could not be detected in the haemolysates from patients with other (brain) diseases. It would be worthwhile to test for this symptom in confirmed, still active (florid) cases of metachromatic leucodystrophy.

Amino Acids↗
PubMed1969

Effects of group contingent events upon classroom noise.

The first study investigated a group control procedure for suppression of excessive sound-intensity levels in a regular public school classroom. Reinforcement consisted of a 2-min addition to the class gym period and a 2-min break after maintenance of an unbroken 10-min quiet period as monitored on a decibel meter. Transgressions of the sound limit (42 decibels) resulted in a delay of reinforcement by the resetting of the timer to the full 10-min interval. The results indicated that these procedures were highly effective in suppression and control of sound intensities. The second experiment utilized a similar procedure coupled with a procedure of eliminating out-of-seat behavior. Experiment III studied the effects of Exp. II procedures on a single student's out-of-seat behavior rate. All procedures were found effective.

Journal Article↗