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Biomedical subjects

W R Hill

Publications and source records attributed to W R Hill.

10 recordsLinked to original sources
PubMed2001

Effects of development time, biomass and ferromanganese oxides on nickel sorption by stream periphyton.

Procedurally defined periphyton frequently includes substantial quantities of hydrous iron (Fe) and manganese (Mn) oxides. As these oxides are strong sorbers of heavy metals, their presence may complicate estimation of metal bioaccumulation by periphyton. We examined the relationship between nickel (Ni) sorption and the development time, biomass, and Fe and Mn oxide content of stream periphyton. Development time, the time during which periphyton accrued on submerged tile substrata, was used to provide variation in biomass, Fe and Mn levels. Stream periphyton from four development times was exposed to Ni for 2 h in the laboratory, and then ashed. Development time was significantly associated with ash-free dry mass (AFDM), Fe and Mn levels (ANOVA, P < or = 0.003). Ni extracted by a mild reductant (hydroxylamine hydrochloride) was significantly associated with development time, and with AFDM, Fe and Mn levels (linear models, P < or = 0.0002). A subsequent acid digestion yielded similar associations with the same variables (linear models, P < or = 0.0001). For both extractions, AFDM was significantly and positively correlated with Fe (r = 0.68 and 0.89) and with Mn (r = 0.77 and 0.93) (Spearman rank, P < or = 0.005). These data demonstrate the importance of periphyton development time in influencing both metal sorption and levels of biomass and ferromanganese oxides. The data also suggest that metal contaminant levels in periphyton should not be attributed automatically to biotic sorption. Periphyton metal-accumulation studies conducted where ferromanganese oxide concentrations are elevated should address the potential metal-sorbing roles of Fe and Mn oxides within the periphyton matrix.

Absorption↗
PubMed1997

PCB congener accumulation by periphyton, herbivores, and omnivores.

The concentrations of 20 polychlorinated biphenyl (PCB) congeners were measured in periphyton, herbivorous fish (stoneroller minnows, Campostoma anomalum), and omnivorous fish (striped shiners, Luxilus chrysocephalus) in an industrially contaminated stream and a reference stream in eastern Tennessee. The sum of the concentrations of the 20 congeners, normalized by dry mass, was one to two orders of magnitude higher in stonerollers and shiners than in periphyton. Normalizing PCB concentrations by lipid mass reduced concentration differences between periphyton and stonerollers, but PCBs per unit lipid in stonerollers were still 50-350% higher than those in periphyton. Shiners had significantly higher lipid-specific PCB concentrations than did stonerollers, so a trophic hierarchy of primary producer < herbivore < omnivore was evident in lipid-specific PCB concentrations. Differences in lipid type, exposure duration, and exposure sources may account for the trophic-level differences in total PCBs. Congener profiles were roughly similar in periphyton, stonerollers, and shiners: five congeners (IUPAC numbers 101, 110, 138, 153, and 180) constituted >60% of the total mass of PCBs analyzed in all three trophic levels. However, stoneroller and shiner tissue was enriched in congeners 153, 118, and 187 relative to periphyton; congeners 153 and 187 are resistant to metabolic breakdown by monooxygenases found in fish liver. Principal component analysis of congener percentages separated periphyton from fish and distinguished between sampling locations.

Animals↗
PubMed1994

Promoting responsible sexual behavior through a college freshman seminar.

A sexual health curriculum has been incorporated into our university's freshman seminar. The effectiveness of this program in changing sexuality-related knowledge, attitude, and behavior in college freshmen was studied. Seven hundred eighty-six freshmen students enrolled in 37 randomly selected English classes were surveyed at baseline and at 3 months. Survey outcome measurements included: knowledge regarding sexually transmitted diseases (STDs), attitudes about sexual behavior, and behaviors including the frequency of barrier contraceptive use, abstinence, and the number of sexual partners. At postintervention, mean knowledge, attitude, and behavior scores were significantly higher for those simultaneously enrolled in the freshman seminar than for those not enrolled. Abstinence among males in the seminar increased. White males in the seminar were more likely to be abstinent or to use a condom than nonwhites. Females not participating in the intervention reported increased frequency of "never" using condoms and decreased frequency of condom use at last intercourse. Students participating in a sexual health curriculum in a college freshman seminar report less frequent high-risk sexual behaviors than students not participating in the seminar.

Adolescent↗
PubMed1992

Rheumatic manifestations of infective endocarditis.

Rheumatic manifestations are common and varied in infective endocarditis. We performed a retrospective case analysis on 87 patients with 93 episodes of infective endocarditis admitted to Flinders Medical Centre over an 11 year period (1980-1990). Disabling musculoskeletal symptoms and signs were documented in 22 (25%) of the patients. Thirteen patients developed severe or moderately severe low back pain during their illness, two with radiological evidence of a septic discitis or vertebral osteomyelitis. Two patients developed polyarthralgia/arthritis, four had septic arthritis (all with acute Staphylococcus aureus endocarditis), three developed severe loin pain, two acute gout, two had severe buttock pain and sacroiliac joint tenderness and two each developed disabling jaw/facial pain, neck/scapular pain and flank pain respectively. Five patients presented initially to the orthopaedic or rheumatological unit for management of their musculoskeletal symptoms. Four of seven patients with Streptococcus bovis endocarditis demonstrated prominent low back pain supporting a previously noted association between this organism and back symptoms. Furthermore, in one patient who had three separate episodes of endocarditis involving three different organisms, florid back symptoms were only seen in the infective episode involving Streptococcus bovis.

Aged↗
PubMed1990

Does steroid pulsing influence the efficacy and toxicity of chrysotherapy? A double blind, placebo controlled study.

To test the hypothesis that early steroid pulsing augments the efficacy and decreases the toxicity of chrysotherapy 40 patients with rheumatoid arthritis were studied in a double blind, placebo controlled study. During the first three months of gold treatment group 1 received monthly intravenous methylprednisolone pulsing (steroid group) while group 2 received placebo (placebo group). All patients were assessed clinically and serologically over a 24 week period. Twelve patients were withdrawn before completion of the study and all but one of the remaining 28 patients reported clinical and serological improvements. Two patients in the steroid group were withdrawn owing to gold induced side effects while four were withdrawn in the placebo group. These small numbers were not significantly different. Minor side effects occurred more commonly in the placebo group. The clinical response was clearly better in the steroid group with statistical significance almost being achieved. In an endeavour to obtain a significant conclusion further patients will now be entered into this study.

Aged↗
PubMed1988

Pancytopenia induced by low-dose methotrexate for rheumatoid arthritis.

Four cases of pancytopenia related to low-dose weekly pulse methotrexate therapy for rheumatoid arthritis are described. All patients were aged above 60 years and had renal impairment. In every case marrow recovery followed withdrawal of methotrexate. However, one patient developed pneumonitis and died. Cholangitis, respiratory infection and increase in methotrexate dose were precipitating factors. Pharmacokinetic data indicated prolonged tissue drug exposure in two cases studied; dose-related toxicity was further supported by successful resumption of methotrexate in reduced dosage in two cases. It is possible that methotrexate dose should be modified during intercurrent illness in patients older than 60 years who have renal impairment.

Aged↗
PubMed1986

Adult onset Still's disease or coxsackie polyarthritis?

The clinical manifestations and laboratory findings of two patients with a presumptive diagnosis of coxsackie B4 virus infection are described. A striking feature was the similarity with adult onset Still's disease, with spiking fever, evanescent macular rash, and severe polyarthritis. This latter feature persisted for many weeks and required steroids to control the symptoms. Review of the literature has supported the proposition that many cases of adult onset Still's disease may be due to coxsackie B4 or other viral infection and it is suggested that these agents should be actively sought in future cases.

Adult↗
PubMed1978

Human eye color and reaction time.

Response latencies to a visual stimulus were determined for 44 male and 82 female Caucasians. Those with dark eyes had significantly shorter simple (one stimulus) reaction times. Complex (one of four stimuli) reaction times showed a similar, but nonsignificant, trend. Data from an additional 206 male Caucasians on a one-trial non-practiced reaction task followed the same nonsignificant trend. Darker iris pigmentation apparently correlates with shorter reaction times but more strongly on practiced tasks and on those which do not involve accuracy.

Eye Color↗