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Biomedical subjects

S Roberts

Publications and source records attributed to S Roberts.

At least 379 records · Page 21Linked to original sources
PubMed1968

Hybridizable ribonucleic acid of rat brain.

1. Cerebral RNA of adult and newborn rats was labelled in vivo by intracervical injection of [5-(3)H]uridine or [(32)P]phosphate. Hepatic RNA of similar animals was labelled by intraperitoneal administration of [6-(14)C]orotic acid. Nuclear and cytoplasmic fractions were isolated and purified by procedures involving extraction with phenol and repeated precipitation with ethanol. 2. The fraction of pulse-labelled RNA from cerebral nuclei that hybridized to homologous DNA exhibited a wide range of turnover values and was heterogeneous in sucrose density gradients. 3. Base composition of the hybridizable RNA was similar to that of the total pulse-labelled material; both were DNA-like. 4. Pulse-labelled cerebral nuclear RNA hybridized to a greater extent than cytoplasmic RNA for at least a week after administration of labelled precursor. This finding suggested that cerebral nuclei contained a hybridizable component that was not transferred to cytoplasm. 5. The rates of decay of the hybridizable fractions of cerebral nuclei and cytoplasm were faster in the newborn animal than in the adult. Presumably a larger proportion of labile messenger RNA molecules was present in the immature brain. 6. Cerebral nuclear and cytoplasmic RNA fractions from newborn or adult rats, labelled either in vivo for periods varying from 4min. to 7 days or in vitro by exposure to [(3)H]-dimethyl sulphate, uniformly hybridized more effectively than the corresponding hepatic preparation. These data suggested that a larger proportion of RNA synthesis was oriented towards messenger RNA formation in brain than in liver.

Animals↗
PubMed1967

Adenosine 3',5'-cyclic phosphate: stimulation of steroidogenesis in sonically disrupted adrenal mitochondria.

Adenosine 3'5'-cyclic phosphate stimulated the conversion of added cholesterol to pregnenolone in "coupled" rat adrenal mitochondria provided with succinate, and in "leaky" mitochondria fortified with reduced nicotinamide adenine dinucleotide phosphate. Adenine nucleotides other than adenosine 3',5'-cyclic phosphate did not duplicate these actions. The cyclic nucleotide was also effective in supernatants from sonically disrupted mitochondria. The minimum effective concentration was 50 micromoles per liter or less. The results suggest that adenosine 3',5'-cyclic phosphate stimulates corticosteroidogenesis by activating the mitochondrial enzymes which are rate-limiting in the utilization of cholesterol.

Adenine Nucleotides↗
PubMed1967

Messenger ribonucleic acid of cerebral nuclei.

1. RNA was isolated from crude nuclear preparations and from ribosomes derived from rat brain and liver. Nuclear RNA was obtained by lysis of the nuclei with sodium dodecyl sulphate, followed by denaturation and removal of DNA and protein with hot phenol. 2. Base composition analyses indicated that the cerebral nuclear RNA preparation contained a higher proportion of non-ribosomal RNA than the analogous hepatic preparation. 3. Sucrose-density-gradient analyses revealed a heterogeneous profile for each nuclear RNA preparation, with two major peaks possessing the sedimentation properties of ribosomal RNA (18s and 28s). 4. Template activities of both preparations were widely distributed through the sucrose density gradients. 5. The cerebral nuclear RNA preparation was more active than the hepatic nuclear RNA preparation in promoting amino acid incorporation in cell-free systems from Escherichia coli and rat brain. 6. Cerebral nuclear RNA stimulated amino acid incorporation in a cerebral ribosomal system even in the presence of an excess of purified E. coli transfer RNA. 7. It is concluded that a significant proportion of cerebral nuclear RNA has the characteristics of messenger RNA.

Journal Article↗
PubMedDate not supplied

Predictive value of serial middle cerebral and renal artery pulsatility indices in fetuses with oligohydramnios.

OBJECTIVE: To determine if unexplained changes in the amniotic fluid index or pulsatility indices of the fetal renal, middle cerebral, or umbilical artery are predictive of perinatal outcome in pregnancies complicated by oligohydramnios. METHODS: Changes in amniotic fluid measurements and fetal vessel velocimetry in patients with oligohydramnios were evaluated for correlation with fetal outcome. Fourteen fetuses with oligohydramnios underwent serial sonography evaluating the amniotic fluid index and fetal middle cerebral, renal, and umbilical velocimetry. Matched controls and neonatal outcomes were obtained. RESULTS: Change in amniotic fluid index and in renal artery pulsatility index were inversely correlated. Change in the middle cerebral artery pulsatility index was different in infants with normal outcome compared to infants with adverse outcome CONCLUSIONS: Serial velocimetry of the middle cerebral artery may identify fetuses with oligohydramnios at risk for adverse outcomes.

Amniotic Fluid↗
PubMedDate not supplied

Type III collagen in the intervertebral disc.

Several collagen types have now been isolated from the intervertebral disc, although type III collagen has previously only been extracted from human pathological disc. In this study, type III collagen has been isolated from normal human and bovine intervertebral disc and immunolocalized in sections of rat, sheep, bovine and 'normal' human intervertebral disc of various ages. Staining with antisera to type III collagen is localized primarily around the cells. Results indicate that cells of the disc sit in 'chondrons', similar to those seen in the deep and mid zones of articular cartilage. We suggest that type III collagen is present in the intervertebral disc and hypothesize that it may be involved in the organization of the pericellular environment, perhaps linking the chondron capsule to the interterritorial matrix.

Animals↗
PubMedDate not supplied

Evaluation of patients undergoing senning repair with two-dimensional contrast echocardiography.

The postoperative anatomy of the Senning interatrial diversion was defined by two-dimensional contrast echocardiography in ten patients. A modified apical four-chamber view proved most valuable, allowing for simultaneous visualization of both the systemic venous atrium and the pulmonary venous atrium. The anatomy was confirmed with two-dimensional contrast echocardiography utilizing catheters placed in the systemic venous atrium and pulmonary venous atrium at the time of surgery. In addition, in several of the patients, we were able to detect atrial or ventricular level shunts which were not clinically apparent. One patient who was judged to have a significant shunt by two-dimensional contrast echocardiography had no anatomic site found at autopsy to explain the shunting. We conclude that two-dimensional contrast echocardiography can define the postoperative anatomy following Senning repair allowing for immediate and future evaluation. Shunting at the atrial and ventricular levels can also be detected, but the method is very sensitive and difficult to quantitate or correlate clinically.

Child, Preschool↗