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Biomedical subjects

R Roth

Publications and source records attributed to R Roth.

162 records · Page 9Linked to original sources
PubMed1973

Chromosome replication during meiosis: identification of gene functions required for premeiotic DNA synthesis.

Recent comparisons of chromosome replication in meiotic and mitotic cells have revealed significant differences in both the rate and pattern of DNA synthesis during the final duplication preceding meiosis. These differences suggested that unique gene functions might be required for premeiotic replication that were not necessary for replication during growth. To provide evidence for such functions, we isolated stage-specific mutants in the yeast Saccharomyces cerevisiae which permitted vegetative replication but blocked the round of replication before meiosis. The mutants synthesized carbohydrate, protein, and RNA during the expected interval of premeiotic replication, suggesting that their lesions preferentially affected synthesis of DNA. The mutations blocked meiosis, as judged by a coincident inhibition of intragenic recombination and ascospore formation. The lesions were characterized as recessive nuclear genes, and were designated mei-1, mei-2, and mei-3; complementation indicated that the relevant gene products were not identical.

Aneuploidy↗
PubMed1970

DNA synthesis during yeast sporulation: genetic control of an early developmental event.

In yeast the mating type alleles a and a also control sporulation; heterozygous strains (a/a) sporulate while homozygous strains (a/a or a/a) do not. Net DNA synthesis, an early event preceding sporulation, occurred normally in the heterozygous strains but did not occur in the homozygous strains. Therefore, the a/a allelles also influence early development well before spore formation begins.

Culture Media↗
PubMed1970

Carbohydrate accumulation during the sporulation of yeast.

The sporulation of Saccharomyces cerevisiae is characterized by an increase in dry weight without cell division. At least 67% of the dry weight increase is due to the synthesis of cellular carbohydrates consisting of trehalose and insoluble components. The insoluble carbohydrates accumulate only during the period preceding the actual formation of visible ascospores. The trehalose accumulates throughout the sporulation cycle and is specifically localized in the ascospore.

Carbohydrates↗
PubMedDate not supplied

Toxicity evaluation of petroleum blending streams: inhalation subchronic toxicity/neurotoxicity study of a light catalytic cracked naphtha distillate in rats.

A 15-week, whole-body inhalation study of the vapors of a distillate (LCCN-D) of light catalytic cracked naphtha (CAS no. 64741-55-5, LCCN) was conducted with Sprague-Dawley rats. Target exposure concentrations were 0, 750, 2500, and 7500 ppm for 6 hours/day, 5 days/week. Over the course of the study, animals received at least 65 exposures. For a portion of the control and 7500-ppm groups, a 4-week postexposure period was included in the study. Subchronic toxicity was evaluated using standard parameters. During life, neurotoxicity was evaluated by motor activity assessment and a functional observational battery. Selected tissues from animals in all exposure groups were examined microscopically. Neuropathologic examination of selected neuronal tissues from animals in the control and high-exposure groups was also conducted. No compound-related effects were seen on survival, clinical chemistry, food consumption, or physical signs. No evidence of neurotoxicity was seen at any exposure level. Slight decreases in hematocrit and hemoglobin concentrations were seen in male rats at the end of exposure to 7500 ppm LCCN-D. However, values were within normal physiological ranges and recovery occurred. Slight decreases in mean body weights and body weight gain were observed in high-exposure females during the first 7 weeks of exposure, but this decrease was not seen during the second half of the study. Male rat nephropathy involving hyaline droplet formation and alpha-2micro-globulin accumulation was seen in mid- and high-exposure males, an effect not relevant to humans. The incidence and severity of goblet cell hypertrophy/hyperplasia and respiratory epithelium hyperplasia in nasoturbinal tissues were greater in high-exposure animals, but recovery occurred. None of the effects observed were considered toxicologically significant. The no-observable-adverse-effect level (NOAEL) for subchronic and neurotoxicity of LCCN-D was > or = 7500 ppm.

Alkanes↗
PubMedDate not supplied

Morbidity, mortality, and albuminuria in type 2 diabetic patients: a three-year prospective study of a random cohort in general practice.

In a 3-year prospective study, the prevalence of albuminuria and its relationship to macrovascular disease, pre-existing vascular risk factors and mortality rate were studied in a random cohort of 290 patients with Type 2 diabetes mellitus in general practice. Newly occurring micro- or macroalbuminuria was associated with significantly (p less than 0.05) higher systolic blood pressure: median (IQ range) 157 (140-170) vs 150 (130-160) mmHg, in addition to higher serum triglycerides: median (IQ range) 2.71 (1.84-4.25) vs 1.84 (1.35-3.14) mmol l-1, and C-peptide levels: median (IQ range) 1.30 (0.98-2.16) vs 1.10 (0.82-1.58) nmol l-1, at 3-year follow-up. Patients with macroalbuminuria at final examination had significantly higher systolic and diastolic blood pressure, serum triglyceride and beta 2-microglobulin levels, decreased HDL-cholesterol, and a significantly higher prevalence of carotid artery stenoses and peripheral vascular disease. Patients dying from vascular causes showed significantly higher urinary albumin levels at entrance as compared to the surviving patients: median (IQ range): 42.2 (11-249.7) vs 10.4 (4.6-28.0) mg l-1, p less than 0.008, and overall mortality rate was significantly linked with the presence of macroalbuminuria (26% vs 5% in normoalbuminuric patients). A comparison between the results of the initial and the final examination indicated an overall worsening of renal variables (albuminuria: median (IQ range): female 9.5 (4.5-21) vs 13.4 (5.1-39.7) mg l-1, (p less than 0.05); male 13.8 (4.7-34.1) vs 32.6 (8.1-78.7) (p less than 0.001), despite a significant improvement in metabolic variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMedDate not supplied

Going by the book at HHS. Shalala v. Guernsey Memorial Hospital.

A recent U.S. Supreme Court decision upheld HCFA's authority to make important reimbursement policy through informal Medicare manuals. The ruling has far-reaching implications for health care providers.

Centers for Medicare and Medicaid Services, U.S.↗
PubMedDate not supplied

Severe hypoglycemia in children and adolescents with IDDM: frequency and associated factors.

Severe hypoglycemia is a very common complication in youths with insulin-dependent diabetes mellitus (IDDM). Seventy four children and adolescents were surveyed for a 1-year period to evaluate the frequency and associated factors of severe hypoglycemia. Patients or their parents completed a standardized questionnaire which inquired about severe and mild episodes, treatment, and prevention of hypoglycemia. Forty-four percent of the patients experienced at least one severe hypoglycemic episode [need for assistance (grade III), loss of consciousness with or without convulsions (grade IV)] during the survey period. The event rate was 0.77 episodes (grade III and IV) per patient-year. The group with severe hypoglycemic episodes was significantly older (mean age, 16.3 years; SD, 3.6 years versus mean age 13.7 years; SD, 4.9 years; p = 0.01) and had significantly longer duration of diabetes (mean, 8.2 years; SD, 4.3 years versus mean, 6.1 years; SD, 4.0 years; p = 0.04) than the group without severe hypoglycemic episodes. There were no significant differences in mean glycosylated hemoglobin (HbA1c), daily doses of insulin, type of insulin regimen, gender, and age at diagnosis between patients who reported severe episodes and those who did not. Mild hypoglycemia was reported by 72 patients. Fifty percent of the patients recognized potential precipitating factors. Older age and longer duration of diabetes seem to predispose the patient to severe hypoglycemia. This may be the result of a diminution of the counterregulation system including lower neuroadrenergic reaction, or the still unphysiologic treatment of diabetes. Continued vigilance and education is important in older adolescents with longer duration of diabetes.

Adolescent↗