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Biomedical subjects

L Roberts

Publications and source records attributed to L Roberts.

At least 325 records · Page 18Linked to original sources
PubMed1983

Pseudosarcoma of the esophagus: barium swallow and CT findings.

Two new patients with pseudosarcoma of the esophagus are presented with the first report of the findings on computerized tomography (CT). The radiographic appearance in the two patients, with 24 previously reported, is reviewed. Barium esophagograms typically demonstrate a large, elongated polypoid mass in the middle or lower third of the esophagus that distends the lumen at the level of the lesion, but does not produce marked obstruction. There are no specific CT characteristics which differentiate pseudosarcoma from squamous cell carcinoma of the esophagus.

Barium Sulfate↗
PubMed1982

Structure and biosynthesis of histocompatibility antigens (H-2, HLA).

Histocompatibility antigens (H-2K, D and L, and HLA-A, B and C) are highly polymorphic cell surface proteins. Their primary structure has been determined by sequencing the protein, complementary DNAs (cDNAs) or genes in several laboratories. H-2Ld and Kd antigens are encoded by eight separate exons: one encodes the signal sequence, three encode the external domains, one encodes the membrane spanning segment and three encode the cytoplasmic domain. A similar structural organization has been found for an HLA gene. H-2 and HLA antigens are synthesized on membrane-bound ribosomes and are co-translationally inserted into the membrane of the endoplasmic reticulum. Here they assemble with beta 2-microglobulin, a small secretory protein. We describe the structure, the membrane insertion in vitro and in vivo, the intracellular transport and the surface expression of these antigens.

Animals↗
PubMed1982

Specific stimulation of the T7 gene 6 exonuclease by the phage T7 coded deoxyribonucleic acid binding protein.

Bacteriophage T7 codes for a single-stranded DNA binding protein. This protein is the product of gene 2.5 and has been found previously to stimulate specifically the activity of the phage-coded DNA polymerase. We report here that the T7 DNA binding protein also stimulates the activity of the phage-coded exonuclease. The gene 6 exonuclease is a double-stranded DNA specific 5'-exonuclease that has been implicated in destruction of bacterial DNA, removal of RNA primers during DNA replication, genetic recombination, and DNA maturation. The enzyme is markedly inhibited by physiological concentrations of NaCl. This inhibition, which is due to a marked reduction in the Vmax of the enzyme, can be largely overcome by the phage-coded DNA binding protein. This stimulation is specific since the Escherichia coli DNA binding protein is without effect. The stimulation by the binding protein is apparently not due to its coating of the 3' single-stranded tails generated during the digestion. Kinetic studies show that the stimulation is due to a combined effect on both the Km and Vmax of the exonuclease. These studies are consistent with a loose binding of the binding protein to either the DNA or the exonuclease.

DNA Helicases↗
PubMed1982

Field study of coccidial and rotaviral diarrhoea in unweaned piglets.

A study of diarrhoea in unweaned piglets was carried out in nine herds, with special reference to the enteropathogenic agents which could be demonstrated. Coccidial (Isospora suis) and rotaviral infections were both identified, either singly or in combination. More extensive studies of I suis infection were undertaken in two of the herds and it was found that diarrhoea occurred most commonly in five- to 14-day-old piglets. Piglets with I suis infection were not necessarily diarrhoeic but grew poorly compared to uninfected piglets. I suis infection in litters correlated with oocyst excretion in sows. In herds with I suis infection, amprolium and monensin were used in the sow ration to achieve control, and in one herd oral dosing of piglets with amprolium in the first three or four days of life was carried out.

Animals↗
PubMed1982

Widening of the subcarinal angle by pericardial effusion.

The subcarinal angle and transverse diameter of the cardiopericardial silhouette were measured on inspiratory posteroanterior radiographs of 54 patients (average age, 43.1 years) with pericardial effusion. The subcarinal angle was significantly greater (p less than 0.001) during effusion (81.0 degrees, n = 54) than either before (62.3 degrees, n = 14) or after (56.7 degrees, n = 21) effusion. A significant (p less than 0.05) positive correlation (r = 0.60, n = 118) was found between the magnitude of the subcarinal angle and the transverse diameter. This suggested that pericardial fluid accumulation displaces the heart and, in turn, splays the main bronchi. When pericardial fluid is not suspected clinically, a widened subcarinal angle, without other evidence of left atrial enlargement, may be a clue suggesting pericardial effusion.

Adolescent↗
PubMed1982

Presence of serum agglutinins to Campylobacter sputorum subspecies mucosalis in pigs.

Pigs affected with intestinal adenomatosis had agglutinating antibodies to Campylobacter sputorum subspecies mucosalis. The titres obtained varied, depending on the strain used as antigen and appeared to rise with the age of the affected animal. Examination of sera from experimental animals showed that pigs between 30 and 77 days old rarely had antibody, even when they had been exposed to infection. Evidence is also presented indicating that the serological response is specific and that in a limited examination of sera derived from pigs at slaughter almost all animals had high levels of antibody.

Abattoirs↗
PubMed1981

Rapid serial cranial computed tomography for tumor diagnosis.

Rapid serial computed tomography (RSCT) provides more information about the cerebral cortical capillary bed and leptomeningeal vessels than conventional enhanced computed tomography (CT). This increased neuroanatomical definition has potential value for separating intra- from extracerebral tumors in selected cases. RSCT offers better visualization of the angioarchitecture of highly vascular tumors than conventional enhanced CT. However, CT scans delayed several minutes after contrast administration are more useful for evaluating the extent of hypovascular tumors. Time-density curves were of limited value for tumor evaluation. However, the peak increase of Hounsfield units did correlate well with the degree of tumor vascularity assessed angiographically.

Adult↗
PubMed1981

RNA splicing mutation in an aberrantly rearranged immunoglobulin lambda I gene.

The mouse cell line MOPC 315 is an IgA (lambda II)-producing myeloma. We have studied a derivative of MOPC 315 that secretes normal lambda II chains but no heavy chain. This derivative, MOPC 315-26, was found to contain a rearranged lambda I gene in addition to a rearranged lambda II gene. The rearranged lambda I gene was cloned into bacteriophage lambda DNA and its structure was studied. The lambda I gene was found to have arisen by an aberrant recombination event that resulted in a single base insertion at the site of V-J region joining. In addition, the gene contained numerous point mutations in the vicinity of the junction of the V and J regions. Two point mutations occurred in the donor splice sequence normally used for the removal of the intron between the J and C regions, suggesting that the RNA synthesized from the aberrantly rearranged lambda I gene would be unable to undergo proper RNA splicing.

Amino Acid Sequence↗
PubMed1980

Hippocampal inhibition of pituitary-adrenocortical function in female rats.

To assess the influence of the hippocampus on ACTH secretion, plasma ACTH concentrations were compared in hippocampectomized and control rats under conditions of differing plasma corticosterone concentrations. In the PM, hippocampectomized rats had higher basal and 2-min ether-stress-induced ACTH concentrations than did cortex-removed controls. Basal PM plasma corticosterone concentrations were also significantly elevated in the hippocampectomized group. In the AM, there were no between-group differences. Adrenalectomy abolished the PM differences between cortical-control and hippocampectomized rats. PM hypersecretion of ACTH in the absence of the hippocampus suggests that this structure contributes an inhibitory component to the neural mechanisms regulating ACTH release. The fact that this increase in hormone concentrations is limited to the PM indicates that there is a circadian variation in hippocampal action.

Adrenocorticotropic Hormone↗
PubMed1980

Mercapto steroids in protection against mercury and lead poisoning.

When thiocholesterol is administered as liposomes, it provides significant protection against methylmercuric chloride in mice when given in three intraperitoneal injections, 0.5 hr before and 2 and 8 hr after the methylmercuric chloride. Thiositosterol, 5 alpha-cholestane-2 beta, 3 alpha-dithiol, and 5 beta-cholane-3 beta, 24-dithiol also are active, but 3 alpha-mercapto-5 alpha-pregnan-20-one, 6 beta-mercapto-5 alpha-cholestane-3 beta, 5 alpha-diol, 3 beta-mercapto-5 beta-cholanic acid, and adamantanethiol are ineffective under these conditions. Adamantanethiol is somewhat effective when administered in soybean oil. Cholestanyl amine was treated with acetylthiosuccinic anhydride to give the half amide; cleavage with hydroxylamine liberated the thiol group. This product is active against both methylmercuric chloride and lead nitrate.

Animals↗