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Biomedical subjects

R L Adams

Publications and source records attributed to R L Adams.

At least 109 records · Page 6Linked to original sources
PubMed1983

Stimulation of de novo methylation following limited proteolysis of mouse ascites DNA methylase.

The ability of mouse Krebs II ascites cell DNA methylase to add methyl groups to native, unmethylated DNA (de novo activity) is stimulated by limited proteolysis. The affinity of the enzyme for DNA is not altered by this treatment but the rate of reaction is increased so that 40% or more of methylatable sites are methylated within 4.5 h. The activation is associated with a decrease in size of the enzyme to 6.2 S.

Animals↗
PubMed1983

Methylation of satellite DNA.

The lower amount of 5 methylcytosine in DNA from bull sperm relative to DNA of other bovine tissues is a result of the absence of this minor base from several of the satellite DNAs in sperm. This applies particularly to the 1.715, 1.711b and 1.709 satellites and less so to the 1.706 and 1.711a satellites. Mouse sperm DNA is also partially undermethylated.

Animals↗
PubMed1983

Chronic renal failure, dialysis, and neuropsychological function.

Hemodialysis patients, nondialyzed azotemic patients and control subjects with chronic physical disabilities were tested in psychometric measures of attention, memory, and visuomotor speed and coordination. There was relatively little difference between the performance of dialysis patients and controls and no significant correlations were found between years of dialysis treatment and performance on any task. In contrast, nondialyzed azotemic patients were impaired on 9 of 14 tasks relative to controls and/or dialysis patients. Measured levels of blood urea nitrogen (BUN) and serum creatinine were significantly correlated with the performance of nondialyzed azotemic patients on several tasks. These results demonstrate a relationship between degree of renal failure and cognitive and perceptual-motor functioning. The mild impairments evident in dialysis patients do not seem to be directly attributable to dialysis treatments. Rather, the onset of hemodialysis appears to have beneficial effects on neuropsychological function.

Adolescent↗
PubMed1983

The effect of dietary lysine levels on performance and meat yields of White Pekin ducks.

Four trials were conducted to determine the effects of dietary lysine levels ranging from .70 to 1.00% on performance and yield of different carcass components of male and female White Pekin ducks. Dietary lysine had no significant effect on weights or feed efficiencies at market age of 48 or 49 days; however, significant differences were obtained with yields of component parts for the males in Trial 2 and the females in Trial 3. In these trials, overall meat yields were significantly better for males fed levels of lysine between .80 and .95% and for females fed a lysine level of .90%.

Animals↗
PubMed1982

The effect of 5-azadeoxycytidine on cell growth and DNA methylation.

By growing cells in the presence of 3 mM thymidine and 5-azadeoxycytidine up to 20% of DNA cytosines have been substituted with azacytosine. No substitution was obtained on incubating with 5-methyldeoxycytidine. Azacytosine-substituted DNA has a very low level of 5-methylcytosine and cells, which survive azadeoxycytidine treatments maintain this low level of methylation in the absence of the drug. The DNA of such cells is undermethylated fairly evenly in all classes of DNA e.g., satellite and unique DNA. Incubation of cells in azadeoxycytidine leads to high cell mortality which is not related to the lack of DNA methylation but may be linked to the altered interactions of proteins with the substituted DNA. This effect, rather than reduced DNA methylation, may be the cause of differentiative changes observed on treatment of cells with 5-azacytidine.

Animals↗
PubMed1982

Clinical utility of the Background Interference Procedure for the Bender-Gestalt test.

Reviewed evidence for the validity of the Background Interference Procedure (BIP) version of the Bender-Gestalt test as a screening test for organic brain dysfunction. Low reliability and shortcomings in BIP validation studies suggest that the diagnostic validity of the BIP is lower than previously reported. A study was conducted in which the BIP was used to determine the presence of absence of brain dysfunction in groups of 45 brain-damaged and 39 nonimpaired male inpatients who were equated for age and education. Both the hit rate (61%) and relative accuracy of the BIP, compared with the EEG and neuroradiological procedures, were lower than in most earlier reports. The results are seen as limiting the usefulness of the BIP as a screening test for brain damage. A potential role for the BIP as a measure of constructional praxis is discussed

Adult↗
PubMed1982

DNA methylation in eukaryotes.

The DNA of higher eukaryotes contains one minor base, namely 5-methylcytosine. The distribution of this minor base between different species and different DNA fractions will be considered together with the actual sequences methylated. The properties of the enzyme responsible for DNA modification will be reviewed, particular note being paid to the efficiency of methylation of different DNA substrates. Various possible functions of the 5-methylcytosine in DNA will be considered and particular attention will be paid to the finding that specific modified bases present in DNA not undergoing transcription are absent in the same genes when these are being actively transcribed.

5-Methylcytosine↗
PubMed1981

DNA methylase during Xenopus laevis development.

The DNA methylase activity present in embryos and cultured cells of Xenopus laevis resembles DNA methylase from mammalian tissues. Little or no activity is found in mature germinal vesicles, though nuclear activity rises rapidly after fertilization. This rise may result in part from a relocation of cytoplasmic enzyme.

Animals↗
PubMed1980

Mental health attitudes and treatment expectations as treatment variables.

Evaluated 60 patients just before their initial assessment in a community mental health clinic. A series of questions about mental health attitudes and treatment expectation were asked each patient. The Psychiatric Evaluation Form was administered both before evaluation and after five treatment visits. Patients with harsh, pessimistic views about mental illness had more severe psychopathology and did less well over the period of follow-up. Expectation of medication was associated strongly with lower education, greater severity of illness, lower satisfaction with treatment, greater frequency of dropping out of treatment, and less improvement.

Adult↗
PubMed1980

A correlation between dropout status and improvement in a psychiatric clinic.

Sixty psychiatric outpatients were independently evaluated before treatment in a mental health center and again after they had either completed five treatment visits or dropped out. Dropouts were older, more likely to be female, more severely ill, and more likely to expect medications. They improved less on scales of drug use, denial of illness, and grandiosity. Dropouts who did improve were more likely to have situational reactions. Better-educated patients had better outcomes. Patients who were satisfied with the treatment they received were the most likely to have improved.

Adult↗
PubMed1979

Methylation of mosquito DNA.

Cells of the mosquito Aedes albopictus have 5.6 pg DNA/cell. This DNA is 58 mol% (A + T) and has about 0.03 mol% each of 5-methylcytosine and 6-methylaminopurine. The DNA is largely degraded by the restriction enzyme HpaII showing the virtual absence of the sequence CMeCGG. Small amounts of enzymic activity recovered largely in non-nuclear fractions transfer methyl groups from S-adenosylmethionine to cytosine and adenine.

Aedes↗
PubMed1979

Mouse DNA methylase: methylation of native DNA.

An improved method of purification of DNA methylase from Krebs II ascites cells is reported. The enzyme sediments at 8.3 S on glycerol-gradients and a major band on SDS polyacrylamide gel electrophoresis has a molecular weight of 184 000. Aggregation occurs at low salt and this may interfere with enzymic activity. The preferred double stranded DNA substrate is that rendered partially unmethylated by an in vitro repair mechanism or by isolation from methionine starved cells. Methylation of native partially methylated DNA is favoured under conditions of low salt and high temperature; conditions which encourage 'breathing' of the DNA. Methylation of native, unmethylated DNA also involves breathing but results in formation of a salt resistant tight binding complex between the enzyme and the DNA.

Animals↗
PubMed1979

Vaginal flora in women undergoing hysterectomy with antibiotic prophylaxis.

One objection occasionally raised against the use of routine antibiotic prophylaxis for pelvic surgery is the concern that the flora of treated patients will be altered, thus favoring the emergence of different, potentially more resistant organisms. This report summarizes experience with 100 women undergoing elective hysterectomy who were subjected to short-term cefazolin, penicillin, or placebo prophylaxis. The changes in preoperative versus postoperative flora were similar among antibiotic-treated and placebo-treated groups. In general, postoperative isolation of gram-negative aerobes and Bacteroides sp increased, and isolation of gram-positive aerobes (except group D streptococci) decreased in antibiotic-treated and placebo-treated groups. The clinical implications of these findings are discussed.

Anti-Bacterial Agents↗