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Biomedical subjects

C R Hardy

Publications and source records attributed to C R Hardy.

5 recordsLinked to original sources
PubMed2000

Development of the gametophytes, flower, and floral vasculature in Dichorisandra thyrsiflora (Commelinaceae).

The flowers of Dichorisandra thyrsiflora (Commelinaceae) are monosymmetric and composed of three sepals, three petals, six stamens, and three connate carpels. The anthers are poricidal and possess a wall of five cell layers (tapetum included). This type of anther wall, not previously observed in the Commelinaceae, is developmentally derived from the monocotyledonous type via an additional periclinal division and the persistence of the middle layers through anther dehiscence. Secondary endothecial thickenings develop in the cells of the two middle layers only. The tapetum is periplasmodial and contains raphides. Microsporogenesis is successive and yields both decussate and isobilateral tetrads. Pollen is shed as single binucleate grains. The gynoecium is differentiated into a globose ovary, hollow elongate style, and trilobed papillate stigma. Each locule contains six to eight hemianatropous to slightly campylotropous crassinucellar ovules with axile (submarginal) placentation. The ovules are bitegmic with a slightly zig-zag micropyle. Megagametophyte development is of the Polygonum type. The mature megagametophyte consists of an egg apparatus and fusion nucleus; the antipodals having degenerated. The floral vasculature is organized into an outer and inner system of bundles in the pedicel. The outer system becomes ventral carpellary bundles. All other floral vascular traces originate from the inner system.

Journal Article↗
PubMed1996

Epidemiology of brain lymphoma among people with or without acquired immunodeficiency syndrome. AIDS/Cancer Study Group.

BACKGROUND: In recent years, brain lymphoma incidence has dramatically increased, presumably because of elevated risk of brain lymphoma among persons with acquired immunodeficiency syndrome (AIDS). PURPOSE: The objective of this study was to estimate independent incidence and survival rates of brain lymphoma among persons with or without AIDS and to understand the epidemiologic features of this cancer. METHODS: We linked AIDS and cancer registry reports at nine state and local health departments and compared the demographics, histology, and survival of brain lymphoma cases among persons with or without AIDS. The data were limited to people under 70 years of age. We calculated the incidence of brain lymphoma among persons with AIDS and compared observed cases with those expected. The differences were statistically analyzed using the Poisson test. Epidemiologic features of brain lymphoma in persons with or without AIDS were compared using the chi-squared test, the Student's t test, and the chi-squared test for linear trend. The logrank test was used to compare survival rates estimated by the Kaplan-Meier technique. All P values were two-sided. RESULTS: We matched 50,989 AIDS registry reports to 859,398 cancer registry reports (data from 1981 to 1990) and found 431 people with both AIDS and brain lymphoma. Among people with AIDS, those developing brain lymphoma versus those without brain lymphoma were more likely to be white (70% versus 59%; P < .001) and had homosexuality as their only human immunodeficiency virus risk factor (75% versus 64%; P < .001). Of the 431 patients, 223 developed brain lymphomas during 47,465 person-years of observation after diagnosis of AIDS. The absolute incidence rate of brain lymphoma among persons with AIDS was 4.7/1000 person-years (95% confidence interval = 4.1-5.3/1000 person-years), 3600-fold higher than the base-line rate in the general population. From 1980 through 1989, overall counts of brain lymphoma increased ninefold. Most of this increase was derived from persons with AIDS, but a substantial increase also occurred among persons without AIDS (0.04/100,000 in 1982 to 0.28/100,000 in 1989) (chi-squared test for trend; P < .05). The median survival was shortest for persons with AIDS and brain lymphoma (2 months), was intermediate for persons with brain lymphoma without AIDS (5-7 months), and was longest for persons with AIDS without brain lymphoma (14 months) (P < .05 for all comparisons). CONCLUSIONS: This analysis distinguishes the separate epidemiologies of brain lymphoma incidence among persons with or without AIDS and shows brain lymphoma incidence among persons with AIDS to be several thousand-fold higher than that in the general population. The study documents the overwhelming effect of AIDS-associated brain lymphoma on the overall rate in the general population and demonstrates a significantly rising trend, although of a lesser magnitude, among persons without AIDS. IMPLICATIONS: This study emphasizes a greater need to bring health care resources to this burgeoning epidemic.

Adult↗
PubMed1982

Formation of halide-ions on one-electron reduction of halogenated nitroimidazoles in aqueous solution. A radiolytic study.

Reactions of e-aq, (CH3)2COH and CO.2- with a series of halogenated nitroimidazoles (ArNO2) results predominantly in the formation of their one-electron reduced species (ArNO.2-), the properties of which are consistent with those of other nitroimidazole radical anions. Further, one-electron reduction of ArNO2 ultimately leads to production of halide ion (X-); G(X-) = 1.2 to 2.2. In the presence of either the nitroxyl free radical, norpseudopelletierine-N-oxyl (NPPN), or oxygen the yield of X- is reduced and 'residual' yields of X- were observed, G(X-) = 0.08 to 0.43. From the results it is suggested that less than or equal to 10 per cent of the yield of reducing species results in the production of X- and an imidazolyl-type radical and that the majority of the yield of X- results from subsequent reactions of ArNO.2- (e.g. bimolecular reactions).

Halogens↗