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Biomedical subjects

A Campbell

Publications and source records attributed to A Campbell.

At least 235 records · Page 13Linked to original sources
PubMed1982

Molybdenum cofactor requirement for biotin sulfoxide reduction in Escherichia coli.

The bisC gene of Escherichia coli is tentatively identified as the structural gene for biotin sulfoxide reductase by the isolation of bisC(Ts) mutants that make thermolabile enzyme. The products of four other E. coli genes (chlA, chlB, chlE and chlG) are also needed for enzymatic activity. Mutations previously assigned to the bisA, bisB, and bisD genes belong to genes chlA, chlE, and chlG, respectively. The biotin sulfoxide reductase deficiency of a chlG, mutant is partially reversed by the addition of 10 mM molybdate to the growth medium. Mutational inactivation of the chlD gene reduces the specific activity of biotin sulfoxide reductase about twofold. This effect is reversed by the addition of 1 mM molybdate to the growth medium. The specific activity of biotin sulfoxide reductase is decreased about 30-fold by the presence of tungstate in the growth medium, an effect that has been observed previously with nitrate reductase and other molybdoenzymes. The specific activity of biotin sulfoxide reductase is not elevated in a lysate prepared by derepressing a lambda cI857 chlG prophage. Whereas biotin sulfoxide reductase prepared by sonic extraction of growing cells is almost completely dependent on the presence of a small heat-stable protein resembling thioredoxin, much of the enzyme obtained from lysates of thermoinduced lambda cI857 lysogens does not require this factor.

Acids↗
PubMed1982

Surveillance and management of patients at high genetic risk for ovarian carcinoma.

The present study is concerned with surveillance/management programs for hereditary ovarian cancer syndromes. These syndromes lack distinguishing premonitory physical signs or biomarkers; therefore, in these genotypic settings, ovarian cancer risk must be assessed by analysis of the patient's pedigree. The authors describe 10 families showing a hereditary proclivity to ovarian carcinoma and/or associated cancer(s) in accord with their respective cancer-prone genotypes. Cancer education, genetic counseling, and surveillance should be instituted early. In addition to bimanual pelvic examination, ultrasound should be tested for its possible efficacy as a screening technique. The option of prophylactic bilateral oophorectomy and hysterectomy is thoroughly discussed with highly selected candidates. The authors believe that the aggressive management approach proposed for ovarian carcinoma is warranted for high-risk members of cancer-prone families, wherein the risk for ovarian cancer may approach 50%.

Adult↗
PubMed1981

Effects of maturation and aging on behavioral responses to haloperidol in the rat.

Male Sprague-Dawley rats were evaluated between ages 18 and 825 days for responses to doses of haloperidol (0 and 0.05-10 mg/kg, IP). Catalepsy, ptosis, and inhibition of general motor activity showed steady decreases in sensitivity to the drug with age during the first 1.5 years of maturation, while rats older than 1.5 years had strikingly increased sensitivity to the activity-inhibiting and cataleptic effects of the drug. The efficacy of haloperidol on all tests in 110-day old rats was indistinguishable whether food was available continuously, or restricted to reduce body weight by 55%, indicating that the effects of maturation are due to aging and not to increasing body weight. The effects may be due to altered drug metabolism or altered sensitivity of the central nervous system to neuroleptic agents. Clinical impressions too, indicate that immature and elderly patients are more sensitive to these and other psychotropic drugs than are young adults.

Aging↗
PubMed1981

DNA sequence of the att region of coliphage 434.

Phages lambda and 434 are related phages that insert at the same site on the Escherichia coli chromosome. A 5.9-kb SalI-BamHI fragment derived from phage 434 was shown to hybridize to a 0.5-kb probe carrying attP-lambda. A 0.8-kb Bam HI-TaqI fragment subcloned into pBR327 was used for sequencing. The sequence of the 500 bp around the insertion site is given here, Comparison of the lambda and 434 sequence shows that the following regions are conserved: the coding sequence for the integrase protein (only 162 bp have been sequenced corresponding to the carboxy terminus), the 15-bp common core at the insertion site, and the three integrase-binding sites flanking the insertion site. The lambda and 434 sequences diverge radically to the left of base-197, suggesting that DNA to the left of that point plays no specific role in insertion or its regulation.

Attachment Sites, Microbiological↗
PubMed1980

Oral bioavailability of apomorphine in the rat with a portacaval venous anastomosis.

Orally administered apomorphine failed to produce stereotyped behavior in sham-operated rats, but did so following portacaval venous anastomosis. Brain and serum levels of apomorphine were highly correlated and corresponded with ratings of stereotypy. Tissue levels were undetectable after oral administration of apomorphine in intact rats but in shunted rats, were similar to those found after s.c. injection. These results suggest that a strong first-pass hepatic metabolism may account for the low oral bioavailability of catechol-aporphines.

Administration, Oral↗
PubMed1980

Sjogren's syndrome and the sicca syndrome: the role of prostaglandin E1 deficiency. Treatment with essential fatty acids and vitamin C.

Lack of adequate synthesis of prostaglandin (PG) E1 may be the key factor in Sjogren's syndrome. PGE1 is important for lacrimal and salivary gland secretion and for T lymphocyte function: a deficiency could therefore account for the main features of Sjogren's syndrome and the sicca syndrome. PGE1 could also account for many of the other features often associated with these syndromes. These include the Raynaud's phenomenon, the abnormalities of renal function and the precipitation of the syndrome by vitamin C deficiency. Vitamin C is important in PGE1 biosynthesis. PGE1 treatment has been shown to correct the immunological abnormalities in the NZB/W mouse, the animal model of Sjogren's syndrome. An attempt to treat humans with Sjogren's syndrome by raising endogenous PGE1 production by administration of essential fatty acid PGE1 precursors, of pyridoxine and of vitamin C was successful in raising the rates of tear and saliva production.

Arthritis, Rheumatoid↗
PubMed1980

Subtotal lesions of the visual cortex impair discrimination of hidden figures by cats.

Cats with partial or nearly total ablation of areas 17, 18, and 19 were assessed on the discrimination of hidden figures and other visually guided behaviors to determine whether such insults produce deficits like those that follow lateral striate lesions in monkeys. Cats with destruction limited to the representation of central vision (Group M) were impaired at discriminating patterns complicated by extraneous cues, but they were less impaired than cats with more complete lesions (Group MS). The deficit was not a general one in visual learning since animals in both Groups M and MS learned simple pattern discriminations as rapidly as controls. It is suggested that the loss of geniculocortical functions representing central vision produces similar deficits in cats and monkeys but that to have this effect in cats, damage must extend beyond area 17.

Animals↗
PubMed1980

DNA sequence of regulatory region for integration gene of bacteriophage lambda.

The cII and cIII proteins specified by bacteriophage lambda direct the lysogenic response to infection through the coordinate establishment of repression and integration of the viral DNA. The regulatory activity of cII/cIII involves positive regulation of two promoter sites: the p(E) promoter, turning on expression of the cI protein that maintains lysogeny, and the p(I) promoter, activating synthesis of the Int protein for integrative recombination. Regulation of the p(I) promoter provides for differential expression of the Int protein with respect to the excision-specific Xis protein from the closely linked int and xis genes. We have determined the DNA sequence of the p(I) promoter region for wild-type lambda DNA and for two classes of mutations: intc mutations, which result in a high rate of Int synthesis in the absence of cII, and deletion mutations, some of which eliminate cII-activated expression of the int gene. We find a sequence with considerable homology (11 of 15 bases) to a "typical" (computer-generated) promoter sequence, adjacent to a region with striking homology (11 of 14 bases) to part of the p(E) promoter region. This presumed p(I) sequence overlaps the start of the xis gene and includes the site of two intc point mutations. A cII-insensitive xis(+) deletion partially removes the proposed p(I) sequence; a deletion that leaves the p(I) sequence intact but terminates 21 bases upstream does not interfere with cII activation of the int gene. From our results and the analysis of the p(E) region, we suggest that cII acts in the promoter -35 recognition region to facilitate binding by RNA polymerase at the -10 interaction region. Differential expression of the int and xis genes results because the p(I) transcript lacks the initiation codon for Xis protein synthesis.

Bacteriophage lambda↗