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Biomedical subjects

C Douglas

Publications and source records attributed to C Douglas.

70 records · Page 4Linked to original sources
PubMed1987

Lung volumes in Polynesian children.

Polynesian (Maori and Pacific Island) children account for approximately one quarter of the children in New Zealand, but good data for lung function in this group are not available. In this review, we report lung volume measurements in 571 healthy children 5 to 13 yr of age: 270 Polynesians (139 boys and 131 girls) and 301 Europeans (177 boys and 124 girls). All measurements were made in a body plethysmograph. Polynesian boys had significantly larger VC, FVC, FRC, TLC, and expiratory reserve volume than did Polynesian girls. Polynesian and European children generally showed different slope and intercept relationships for the prediction of lung volume from height. Racial differences are not adequately explained by differences in body proportions or social factors including parental smoking. Possible explanations include racial differences in lung growth and maturation.

Adolescent↗
PubMed1986

Rhizobium meliloti genes required for nodule development are related to chromosomal virulence genes in Agrobacterium tumefaciens.

Symbiotically essential genes have been identified in Rhizobium meliloti that are structurally and functionally related to chromosomal virulence (chv) genes of Agrobacterium tumefaciens. Homologous sequences also exist in the genomes of other fast-growing rhizobia including Rhizobium trifolii, Rhizobium leguminosarum, and Rhizobium phaseoli. In Agrobacterium, the chvA and chvB loci are known to be essential for oncogenic transformation of dicotyledonous plants and for attachment to plant cells [Douglas, C. J., Staneloni, R. J., Rubin, R. A. & Nester, E. W. (1985) J. Bacteriol. 64, 102-106], and the chvB locus has been implicated in the production of (1-->2)-beta-glucan, a unique exopolysaccharide component [Puvanesarajah, V., Schell, F. M., Stacey, G., Douglas, C. J. & Nester, E. W. (1985) J. Bacteriol. 164, 102-106]. Site-directed transposon insertion mutants in the chvA and chvB-equivalent regions of R. meliloti are symbiotically defective. Mutants in the chvB-equivalent region have been examined in detail and have been found to induce the formation of nodule-like structures on alfalfa that are devoid of bacteroids, lack infection threads, and cannot fix nitrogen. Such mutants fluoresce normally in the presence of Calcofluor, a histochemical stain for beta-linked polysaccharides, and produce normal amounts of total exopolysaccharide. The Rhizobium loci have been designated ndv because of their requirement for nodule development.

Journal Article↗
PubMed1986

Transitory stimulation of human platelet 12-lipooxygenase by vitamin E supplementation.

Human platelet lipooxygenase converts arachidonic acid to 12-hydroperoxy-eicosatetraenoic acid (12-HPETE), which is rapidly reduced by peroxidases to 12-hydroxy-eicosatetraenoic acid (12-HETE). This study was conducted to examine the effect of vitamin E supplementation on platelet 12-lipooxygenase activity. Sixteen healthy subjects were supplemented with 400 IU/day of either D-alpha-tocopherol (268 mg) or DL-alpha-tocopherol (364 mg) for 4 wk. Supplements elicited a transitory increase of lipooxygenase activity but a suppression of peroxidase activity, as indicated by increased 12-HETE production and 12-HPETE accumulation. Plasma-tocopherol concentration was double the presupplement value and remained stable during supplementation. Neither age, sex, nor isomeric form of tocopherol supplement significantly influenced the pattern of response. Results show that vitamin E exerts a differential effect on platelet lipooxygenase and peroxidase activities.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1985

Specific attachment of Agrobacterium tumefaciens to bamboo cells in suspension cultures.

Agrobacterium tumefaciens was tested for its ability to attach to tissue culture cells of bamboo, a monocotyledonous plant. Phase-contrast microscopy and kinetic experiments with radiolabeled bacteria showed that attachment to bamboo cells was indistinguishable from attachment to cells of dicotyledonous plants. Bacterial mutants defective in attachment to dicotyledonous plants showed similar behavior with bamboo, and extensive washing of the bamboo cells had no effect on the number of bacteria which attached.

Adhesiveness↗
PubMed1979

Factors Affecting Crown Gall Tumorigenesis in Tuber Slices of Jerusalem Artichoke (Helianthus tuberosus, L.).

Agrobacterium tumefaciens can induce tumors on thin slices which are excised from Jerusalem artichoke (Helianthus tuberosus) tubers and grown in culture on medium containing minerals and a carbon source. A comparative study was made of the kinetics of cell division in slices under three conditions: (a) slices which were untreated and showed only spontaneous (wound-induced) cell divisions; (b) slices treated with indoleacetic acid at several concentrations; and (c) slices treated with virulent or avirulent bacteria. The earliest spontaneous cell divisions were completed (as detected by the appearance of new daughter cell pairs) by about 3 hours. These cells divide only once. In indoleacetic acid-treated tissue, more cells divide, with the first cell pairs being detected slightly earlier than in slices not subjected to the hormone. The number of cells which divide is roughly proportional to auxin concentration. Tissue treated with virulent bacteria showed only the pattern of spontaneous cell division until about 72 hours, after which another burst of cell division commenced and continued indefinitely. The bacteria-induced growths produced the unusual amino acids which are characteristic of crown gall tumors. The percentage of slices with tumors was sharply reduced if certain avirulent A. tumefaciens strains were applied prior to virulent strains.

Journal Article↗
PubMed1978

Argon laser iridotomy in the treatment of patients with primary angle-closure or pupillary block glaucoma: a clinicopathologic study.

A "pulsed" argon laser was successful in 48 of 64 (75%) attempted laser iridotomies. Scanning and transmission electron microscopy performed on specimens taken at varying intervals following laser treatment revealed progressive scarring of iris tissue. The complications appear minimal at this time, but longer follow-up is required before it can be stated that laser and surgical peripheral iridectomies are comparable. However, the laser's simplicity and ease of administration appear to warrant its continued use at this time.

Argon↗
PubMedDate not supplied

Value of screening for markers of hepatitis in dialysis units.

The value of monitoring the serum activity of SGOT, as well as markers of hepatitis B virus and hepatitis A virus infections, in the patients and staff of two dialysis units has been assessed retrospectively. Sera were checked each month for SGOT and HBsAg on 406 patients and 170 staff members over a 4-year period. Anti-HBc, anti-HBs, and anti-hepatitis A antibodies were assayed on the stored sera. Only 30% of the patients had normal SGOT values (less than 65 units per ml) on all occasions. Most of the abnormal values were less than 100 units per ml and could not be explained. Viral hepatitis was a reasonable explanation for only half of those instances where the SGOT value was greater than 100 units per ml. Hepatitis A virus contributed nothing to the problem of dialysis-associated liver disease. Testing for HBsAg alone missed approximately 40% of the hepatitis B events acquired in the unit. Only two of these episodes were of epidemiologic importance, however, because the rest were recognized only after there was serologic resolution of the infection. There was a high frequency of potentially "false positive" reactions with all the antibodies tested. It is not cost-effective to monitor dialysis patients and staff regularly with anti-HBc, anti-HBs, or antibodies against hepatitis A. Initial screening with anti-HBc and anti-HBs on entry to the unit is of value but weak positive results must be interpreted with caution since approximately half of such results will prove to be nonspecific.

Antibodies, Viral↗
PubMedDate not supplied

Familial iridoplegia.

Fixed, dilated pupils in childhood are usually due to interruption of parasympathetic innervation as a result of neurologic impairments or occur following pharmacologic mydriasis. We present a familial form of iridoplegia without structural defects of the eye which is consistent with a probable autosomal dominant mode of inheritance. Examination of other family members should be part of an affected individual's evaluation particularly when this finding occurs as an isolated defect. Recognition of such an entity may avoid unnecessary neurodiagnostic studies in an affected individual.

Child, Preschool↗