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Biomedical subjects

R Evans

Publications and source records attributed to R Evans.

At least 19 recordsLinked to original sources
PubMed1979

Loss of rac locus DNA in merozygotes of Escherichia coli K12.

DNA-DNA hybridization was used to demonstrate that the substituted DNA in the bacteriophage lambda recE (formerly called lambda reverse) is homologous to DNA at the rac locus in Escherichia coli. Strains that are rac- do not contain appreciable amounts of this DNA, and it is lost from a rac+ episome (F' 123) after transmission to a rac- recipient. This is consistent with the proposal that the rac locus contains a cryptic prophage (Low, 1973).

Bacteriophage lambda↗
PubMed1979

The synthesis and processing of a nuclear RNA precursor to rat pregrowth hormone messenger RNA.

A recombinant DNA plasmid, pBR322-GH1, which contains about 80% of the sequences of rat pregrowth hormone (pGH) mRNA, allowed an analysis of nuclear RNA from GH3 cells for possible precursors of cytoplasmic pGH mRNA. A single 20-22S RNA SPECIES ABOUT 2-3 TIMes larger than pGH mRNA was detected in nuclear RNA from GH3 cells labeled for 5 min. with 3H-uridine. After longer label times a 12S RNA indistinguishable in size from cytoplasmic 12S pGH mRNA became the predominant labeled RNA complementary to the plasmid pBR322-GH1. Both of these nuclear RNA species contained poly (A). Kinetic analysis of the labeling of nuclear and cytoplasmic pGH mRNA sequences showed that the 20S and 12S nuclear RNA molecules were labeled before significant labeling of cytoplasmic pGH mRNA was detected, and also indicated that there is complete conservation of nuclear pGH mRNA sequences in the production of cytoplasmic pGH mRNA. These results indicate that cytoplasmic pGH mRNA is generated by nuclear processing of a larger nuclear RNA molecule.

Animals↗
PubMed1979

Rat growth hormone gene: intervening sequences separate the mRNA regions.

Rat genomic DNA was digested with various restriction endonucleases, separated by gel electrophoresis and hybridized to 125 I-labeled mRNA for the precursor protein to growth hormone. Restriction sites were found within the genomic DNA that were not found in the previously reported DNA sequence corresponding to the mRNA (19). It appears that the gene for growth hormone contains intervening sequences separating the DNA regions that specify mRNA sequences.

Animals↗
PubMed1979

Alpha-adrenergic hyper-responsiveness in asthma.

Because alpha-adrenergic stimulation causes bronchoconstriction, the alpha-adrenergic responsiveness of 21 subjects with allergic asthma was compared with that of 16 subjects with allergic rhinitis and 38 normal control subjects. None of the patients had taken medications for at least 30 days before study. Alpha-adrenergic responsiveness was measured by the capacity of phenylephrine to constrict the cutaneous vascular bed and to dilate the pupillary sphincter muscle. Asthmatic subjects required 4.0 +/- 0.6 ng to reduce their cutaneous blood flow by 50 per cent, whereas normal controls required 32.0 +/- 7.5 ng (P less than 0.005) and subjects with allergic rhinitis required 23.7 +/- 9.4 ng (P less than 0.02). The pupils of asthmatic subjects dilated by greater than 0.5 mm in response to 1.8 +/- 0.14 per cent phenylephrine, patients with allergic rhinitis required 2.4 +/- 0.16 (P less than 0.01), and normal controls needed 2.7 +/- 0.07 (P less than 0.00001). Therefore, the patients with allergic asthma had significantly enhanced alpha-adrenergic responses when compared both to normal subjects and patients with allergic rhinitis; the possibility that increased alpha-adrenergic activity contributes to the asthmatic diathesis warrants further exploration.

Adolescent↗
PubMed1979

Evaluation of ultra-short dialysis.

A study was carried out to compare the effects of three dialysis regimens of different durations. Nineteen patients dialysed over 1975--7 for an average of only 11.2 hours per week were compared with nine dialysed for 24 hours per week (1974--6) and 10 dialysed for 27 hours (1971--3). Clinical, biochemical, and haematological results showed that the short dialysis regimen was as effective as the longer regimens, except that patients had to take a phosphate binder regularly, and that it was considerably cheaper. Short dialysis has social and economic benefits, since patients have more free time and more patients can be treated with the same number of staff and dialysis stations. As in many areas there is a shortage of places for patients needing dialysis, a short regimen is recommended.

Evaluation Studies as Topic↗
PubMed1979

Evaluation of a patient with cold and cholinergic urticaria.

A-20-year-old male Army paratrooper presented with a history of inducible urticaria associated with exercise as well as cold exposure. Upon evaluation, he not only had a positive ice cube test, but also had a positive mecholyl skin test with numberous satellite lesions and generalized punctate urticaria following exercise challenge. Thus, he appeared to have combined cold and cholinergic urticaria. When mediator release was examined during cold and exercise challenge, histamine release was observed in each instance; a rapid rise and fall of plasma histamine was seen after cold challenge, while a lag phase followed by sustained elevation of plasma histamine was associated with exercise challenge. This represents the fourth reported case of combined cold and cholinergic urticaria and is the first in whom mediator release was assessed. The time-course of histamine release was characteristic of each disorder.

Adult↗
PubMed1979

Injuries produced by shattering annealed glass.

Attention is drawn to the significant number of accidents related to plate (annealed) glass, and the relative paucity of information available on the subject. Four cases of life-threatening injuries secondary to accidents involving annealed glass are described and illustrated. It is suggested that the use of one of the types of safety glass already available should be made mandatory universally, but particularly in those locations defined as 'risk areas' by the British Standards Code of Practice (CP 152) on glazing in the construction industry.

Abdominal Muscles↗
PubMed1979

Calcium infusion: a new provocative test for insulinomas.

Calcium gluconate (10 mg Ca(++)/kg) was administered intravenously over a 2-hour period to 16 adult patients who were evaluated for hypoglycemia. In nine of ten patients with benign or malignant insulinomas (eight proven at operation, and two with positive chemical tests and angiographic localization awaiting operation), significant hypoglycemia and hyperinsulinemia occurred within 60 to 90 minutes after the start of the calcium infusion. Serum proinsulin and Cpeptide concentrations increased at the time of the calciuminduced hyperinsulinemia in several patients in whom these parameters were studied. The one individual who did not respond to the calcium infusion was found to have a benign insulinoma. His basal glucose/insulin ratio of 0.64 was the lowest of the insulinoma group and thus his failure to respond to calcium may indicate that his tumor was secreting maximally at the time of the infusion. Following successful removal of the insulinoma, calcium infusion did not result in changes in serum glucose or insulin concentrations (tested in five patients). In contrast, neither a patient with pathologically documented islet cell hyperplasia, five others with reactive, fupctional or drug-induced hypoglycemia, nor four healthy volunteers showed any changes in circulating glucose or insulin levels while receiving calcium intravenously. Calcium infusion is a safe, rapid and effective provocative test for the diagnosis of insulin-secreting, islet cell tumors of the pancreas.

Adenoma, Islet Cell↗
PubMed1979

The use of hemoperfusion as an adjunct to hemodialysis.

Studies are reported on the use of short dialysis, sequential ultrafiltration/short dialysis and hemoperfusion in chronic renal failure. Short dialysis (less than 12 hours/week) is a satisfactory regime with good patient acceptance, adequate small and middle molecule clearance and control of fluid and blood pressure. Sequential ultrafiltration in the first hour improves fluid removal and reduces the side effects of dialysis. The addition of hemoperfusion increases clearance of small and middle molecules and has little effect on the osmolality of the serum. Thus, it does not increase the side effects of dialysis. Preliminary results suggest that hemoperfusion may be useful in the treatment of chronic renal failure in combination with ultrafiltration and dialysis.

Carbon↗
PubMed1979

Genetic and physiological characterization of Pseudomonas aeruginosa mutants affected in the catabolic ornithine carbamoyltransferase.

In Pseudomonas aeruginosa arginine can be degraded by the arginine "dihydrolase" system, consisting of arginine deiminase, catabolic ornithine carbamoyltransferase, and carbamate kinase. Mutants of P. aeruginosa strain PAO affected in the structural gene (arcB) of the catabolic ornithine carbamoyltransferase were isolated. Firt, and argF mutation (i.e., a block in the anabolic ornithine carbamoyltransferase) was suppressed specifically by a mutationally altered catabolic ornithine carbamoyltransferase capable of functioning in the anabolic direction. The suppressor locus arcB (Su) was mapped by transduction between hisII and argA. Second, mutants having lost suppressor activity were obtained. The Su- mutations were very closely linked to arcB (Su) and caused strongly reduced ornithine carbamoyltransferase activities in vitro. Under aerobic conditions, a mutant (PA0630) which had less than 1% of the wild-type catabolic ornithine carbamoyltransferase activity grew on arginine as the only carbon and nitrogen source, at the wild-type growth rate. When oxygen was limiting, strain PA0630 grown on arginine excreted citrulline in the stationary growth phase. These observations suggest that during aerobic growth arginine is not degraded exclusively via the dihydrolase pathway.

Crossing Over, Genetic↗
PubMed1979

Immunotherapy in atopic disorders.

Immunotherapy plays an important role in the treatment of allergic rhinitis, asthma, and insect sting allergy. In the latter circumstance, immunotherapy with specific venom from the stinging insects can be life saving. Most commonly employed in immunotherapy are aqueuos extracts of aeroallergens, particularly plant pollen, and mold spores. Recent advances suggest that modification of these allergens, such as polymerization, can result in improved symptom response with fewer side effects. Efficacy trials of immunotherapy have demonstrated satisfactory treatment responses in allergic rhinitis and allergen-induced asthma. These responses, as measured by changes in symptom scores, are attended by specific immunologic changes summarized in Table 2.

Allergens↗