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Biomedical subjects

D Gottlieb

Publications and source records attributed to D Gottlieb.

At least 73 records · Page 4Linked to original sources
PubMed1985

Immediate spasticity with acute hemiplegia is a sign of basal ganglia hemorrhage.

Acute appearance of hemiparesis or hemiplegia with initial marked spasticity was observed in 8 stroke patients. All had intracerebral hematomas and in 7 it was located in the region of the basal ganglia. By contrast, none of 121 hemiplegic patients with hemispheric ischemic stroke hospitalized during the same period had increased muscle tone in the involved limbs at stroke onset. Study indicates that association of hemiplegia with immediate spasticity at stroke onset is a clinical clue to a possible deeply located intracerebral hematoma.

Aged↗
PubMed1981

Importance of antibiotic production in antagonism of selected Streptomyces species to two soil-borne plant pathogens.

Antagonism of ten Streptomyces spp., five of which produce antibiotics, to the plant pathogens Rhizoctonia solani and Phytophthora megasperma var. sojae was studied. Antibiotic activity was detected in culture for the five antibiotic producers. S. griseus, S. hygroscopicus var. geldanus, and S. noursei produced wide zones of inhibition to R. solani and P. megasperma var. sojae. Similar activity was found for S. reticuli var. protomycicus to P. megasperma var. sojae. S. cellulosae reduced Rhizoctonia root rot on pea when sterile soil was infested simultaneously with the antagonist and R. solani. S. hygroscopicus gave almost complete disease control when the streptomycete was added 7 days prior to infesting the soil with R. solani. Several of the Streptomyces spp. reduced Phytophthora root rot on soybean when the streptomycetes were added to soil at the same time as P. megasperma var. sojae or 7 days prior to adding the pathogen. S. herbaricolor and S. coeruleofuscus gave the most consistent control. No relationship was found between reported antibiotic activity or antagonism on agar media and reduction in disease severity. Only S. hygroscopicus var. geldanus gave both control of Rhizoctonia root rot and large zones of inhibition on agar media when the streptomycetes were preincubated in soil for 7 days.

Anti-Bacterial Agents↗
PubMed1978

Evidence from mycelial studies for differences in the sterol biosynthetic pathway of Rhizoctonia solani and Phytophthora cinnamomi.

Phytophthora cinnamomi, a member of the Pythiacease, does not synthesize sterols. Small amounts of squalene, but no squalene epoxide or sterol, were isolated from the dried mycelium of this fungus after growth in sterol-free medium. The dried mycelium of Rhizoctonia solani, a sterol-synthesizing fungus grown under the same conditions, contained small amounts of squalene and squalene epoxide and large amounts of ergosterol. When the two organisms were grown in the presence of [14C]acetate, only labelled geraniol, farnesol and squalene were recovered from the P. cinnamomi mycelium, whereas labelled geraniol, farnesol, squalene, squalene epoxide and ergosterol were recovered from the R. solani mycelium. Similar results were obtained when the organisms were incubated in the presence of [2(-14)C]mevalonate; in this case, labelled lanosterol was also detected in the R. solani mycelium. Both organisms, when incubated in the presence of unlabelled squalene, squalene epoxide or lanosterol, incorporated these compounds into their mycelia; however, only the R. solani mycelium was able to convert these substrates into products further along the sterol pathway. It appears that squalene is the terminal compound in the sterol biosynthetic pathway of P. cinnamomi.

Acetates↗
PubMed1978

Evidence from cell-free systems for differences in the sterol biosynthetic pathway of Rhizoctonia solani and Phytophthora cinnamomi.

Cell-free preparations of both Rhizoctonia solani, a sterol-synthesizing fungus, and Phytophthora cinnamomi, a non-sterol-synthesizing fungus, incubated in the presence of [2(-14)C]mevalonate and iodacetamide, converted the mevalonate into labelled mevalonate 5-phosphate, mevalonate 5-pyrophosphate and isopentenyl pyrophosphate. In the absence of iodoacetamide, but under anaerobic conditions, the same preparations converted the mevalonate into labelled geraniol, farnesol and squalene, the first two compounds presumably as their pyrophosphates. When cell-free preparations of both organisms were incubated aerobically in the presence of [1(-14)C]isopentenyl pyrophosphate, only labelled geraniol, farnesol and squalene were recovered from the P. cinnamomi reaction mixture, whereas labelled geraniol, farnesol, squalene, squalene epoxide, lanosterol and ergosterol were present in the R. solani reaction mixture. When these same preparations were incubated in the presence of 14C-labelled squalene, labelled squalene epoxide, lanosterol and ergosterol were recovered from the R. solani reaction mixture. In contrast, the P. cinnamomi preparation was unable to convert the squalene into products further along the sterol pathway; instead, a portion of the labelled squalene was converted into water-soluble products, indicating the possible existence of a squalene-degradation process in this organism. It appears that the block in the sterol biosynthetic pathway of P. cinnamomi occurs at the level of squalene epoxidation.

Alkenes↗
PubMed1976

Methylation and aging in Rhizoctonia solani.

Our earlier studies had shown that as fungi age, many of their vital functions decrease; in Rhizoctonia solani, protein synthesis is one of the functions so affected. We now find that the ability to methylate tRNA, a vital component of the protein synthesizing system, also decreases with age. This methylation of Escherichia coli tRNA by R. solani methylase preparations increased with the concentration of enzyme and with time of incubation; in both cases the rate of increase was considerably higher for preparations from young cells than for those from old cells. The methylation reaction also increased with the concentration of substrate tRNA, with temperature, at least to 45 degrees C, and with pH to 9.0. Methylase preparations from R. solani methylated both exogenous E. coli tRNA and yeast tRNA, but were only weakly active on isolated R. solani tRNA. However, acid-precipitated methylases from R. solani were very effective in methylating the homologous exogenous tRNA. Regardless of the source of the tRNA used as substrate, the methylases from older cells were always less active than those from young cells from the same mycelium. No methylase inhibitor was detected in the fungus.

Escherichia coli↗