Reuber hepatoma H-35 was found to retain the activity of carbamoyl-phosphate synthetase I. The content of this enzyme in H-35 grown in Eagle's minimal essential medium was about half that in rat liver. The enzyme from H-35 was the same as that from rat liver in molecular weight estimated by SDS-polyacrylamide gel electrophoresis, specific enzyme activity, kinetic parameters for ATP and N-acetyl-L-glutamate, and immunological crossreactivity. The enzyme in H-35 was induced by dexamethasone (1.4-fold) but not by glucagon or dibutyryl cAMP. Incorporation of [35S] methionine into the enzyme indicated that the effect of dexamethasone was due to increased synthesis of the enzyme protein (2.1-fold). By labeling with [35S]methionine, the precursor and the mature forms of carbamoyl-phosphate synthetase I were observed in the post-mitochondrial and mitochondrial fractions, respectively. By chasing the labeled cells with unlabeled methionine and cycloheximide, it was observed that the rate of translocation of the precursor into mitochondria is not affected by dexamethasone.

Animals↗

PubMed1983

In vivo study of developmental changes in carbamoyl-phosphate synthetase I in rat liver. Repression of the enzyme synthesis immediately after birth.

The regulatory mechanism of the developmental increase of carbamoyl-phosphate synthetase I in fetal and neonatal rat liver was studied in vivo. The appearance and rapid increase of the enzyme in late fetal period were caused by de novo synthesis of the enzyme protein. The amount of the enzyme protein analyzed by SDS-polyacrylamide gel electrophoresis was proportional to the enzyme activity throughout the period of development. No indication was observed for preexisting protein which could be converted into the active protein. A novel system for the in vivo study of carbamoyl-phosphate synthetase I synthesis was developed. Hepatocytes, mechanically dispersed by repeated passage of the tissue through a pipet, incorporated [35S]methionine into the enzyme. Taking advantage of this system, the regulation of the enzyme synthesis was studied. In vivo synthesis of the enzyme was detected at 4 days before birth and rapidly increased until 1 day before birth. However, the enzyme synthesis was markedly repressed after birth, when the amount of carmamoyl-phosphate synthetase I itself reached the adult level. This result was in a clear contrast with the constant level of the translatable mRNA (Raymond, Y. and Shore, G.C. (1981) Biochim. Biophys. Acta 656, 111-119) and suggested that post-transcriptional regulation is important in addition to the level of mRNA for the regulation of the carbamoyl-phosphate synthetase I level.

Aging↗

PubMed1983

Creutzfeldt-Jakob disease: a case with extensive white matter degeneration and optic atrophy.

A 52-year-old woman is described, whose clinical features were typical of Creutzfeldt-Jakob disease except for the presence of optic atrophy. Serial CT scans showed rapid development of brain atrophy early in the course. Postmortem examination revealed extensive degeneration of the cerebral and cerebellar white matter and of the optic nerves in addition to the classic findings of Creutzfeldt-Jakob disease. It is suggested that both the grey and white matter may undergo a severe destructive process early in the course of the disease, and the possibility is discussed that the white matter involvement is not a result of neuronal loss.

Brain↗

PubMed1983

Prognostic value of cerebral blood flow autoregulation in the long-term prognosis of ischemic cerebrovascular disease.

The correlation between long-term prognosis, cerebral blood flow (CBF) and CBF autoregulation was studied in 34 patients with cerebral infarction (mean age, 64 years). CBF was measured by the nitrous oxide method 1-6 months (mean 87 days) after disease onset. CBF autoregulation was evaluated quantitatively from the Dysautoregulation Index (DI) (delta CBF/delta effective MABP). Reductions in effective MABP were induced with a tilt table. No significant correlation was noted among CBF, DI and activities of daily living at the time of measurement. The patients' physical condition was reevaluated by questionnaire 2 years or more (mean 32 months) later. Better functional state at follow-up was related to higher CBF and lower DI values although the differences were not significant. The relationships among CBF, DI and changes in physical condition during the period were evaluated. The mean CBF values in patients with a better prognosis exceeded those of poor prognosis patients. The CBF values in the group who became independent significantly exceeded those in the group that deteriorated (P less than 0.05). The CBF values in the latter showed small but significant decreases during head-up tilting (P less than 0.05). The DI in this group was significantly higher than in the groups with a less severe outcome (P less than 0.01, P less than 0.05, respectively). In conclusion, determinations of CBF autoregulation, together with flow values, in the chronic state may have some value in predicting the long-term prognosis in cerebral infarction.

Adult↗

PubMed1983

The effect of abdominal pressure on urinary flow rate.

We examined the effect of abdominal pressure on urinary flow rate and urethral closure pressure in 46 subjects, ranging in age from 26 to 82 years. An increase in urinary flow rate caused by abdominal straining was not found when organic obstruction was present in the prostatic urethra in men or the proximal urethra in women, or when dysuria is caused by the lowered detrusor pressure. An increase in urinary flow rate caused by straining was noted when anterior urethral stricture or stress incontinence was present. The increase in urinary flow rate owing to straining was undetermined in the control group. The urethral closure pressure on the anti-stress incontinence zone increased as a result of straining at the same time and to the same degree as did the intravesical pressure. When the anti-stress incontinence zone was subjected to transurethral resection for canal formation urination became possible as a result of straining. The patients who were able to urinate with straining sometimes suffered temporary stress incontinence. The degree of straining did not determine whether the patient could urinate with straining. Therefore, it was concluded that abdominal pressure should be excluded from intravesical pressure in performing several urodynamic studies on the lower urinary tract, such as pressure flow studies, and that it is important to have a sufficient canal formation in the anti-stress incontinence zone when urination with straining is expected when performing an operation on patients with urethral obstruction in the anti-stress incontinence zone.

Abdomen↗

PubMed1983

Role of glucagon in increase of hepatic glycerate kinase of adult and neonatal rats.

An increase of rat liver glycerate kinase [ATP: D-glycerate 2-phosphotransferase EC 2.7.1.31] on protein feeding, on starvation or during fetal and neonatal development was studied from the viewpoint of the role of glucagon as the mediator. On starvation and during fetal and neonatal development, glycerate kinase in the cytosolic and mitochondrial fractions increased approximately in the same ratio. Glucagon in plasma increased under these conditions and glucagon administration increased glycerate kinase in both intracellular fractions approximately in the same ratio. The above results suggested that glucagon functions as at least one of the mediators for these processes. In diabetic rats, only a slight increase of the enzyme in both intracellular fractions was observed. Protein feeding, however, strongly increased the mitochondrial enzyme. Glucagon failed to mediate this function of dietary protein for the mitochondrial enzyme.

Age Factors↗

PubMed1983