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Biomedical subjects

R W Wilson

Publications and source records attributed to R W Wilson.

At least 19 recordsLinked to original sources
PubMed2005

The integration of behaviour into comparative physiology.

Comparative physiology has traditionally focused on the physiological responses of animals to their physicochemical environment. In recent years, awareness has increased among physiologists of the potential for behavioural factors, such as the social environment of the animal, to affect physiological condition and responses. This recognition has led to an emerging trend within the field toward using multidisciplinary approaches that incorporate both behavioural and physiological techniques. Research areas in which the integrated study of behaviour and physiology has been particularly fruitful include the physiology of the social environment, sensory physiology and behaviour, and physiological constraints on behavioural ecology. The manner in which incorporating behavioural considerations has informed the physiological data collected is discussed for each of these areas using specific examples.

Animals↗
PubMed2005

Pilot study of a home-based aerobic exercise program for sedentary cancer survivors treated with hematopoietic stem cell transplantation.

We report a pilot study of a home-based aerobic exercise program in a group of 17 adult hematopoietic stem cell transplant (HSCT) recipients. Participants had received no cancer treatment for at least 6 months and reported leisure time physical activity less than 20 min per day and fewer than three times a week during the previous month. Following baseline assessments of aerobic fitness, fatigue symptoms, and quality of life, participants were placed on home-based aerobic exercise programs consisting of 20-40 min of activity in the target heart rate zone (40-60% predicted heart rate reserve) delivered in three to five sessions per week for 12 weeks. Subjects were supplied with electronic heart rate monitors and we encouraged program adherence using weekly telephone contacts and exercise diaries. In all, 32 of the 42 qualified candidates consented (acceptance=76%). Of these, 17 kept appointments for baseline assessments, four did not complete the study (attrition=46%), and no exercise-related adverse events were reported. Scores on measures of aerobic fitness, fatigue severity, and physical well-being improved (signed ranks test; P<0.05) during program participation. Our findings suggest that individually prescribed, home-based aerobic exercise is an acceptable, safe, and potentially effective intervention for improving physical functioning and fatigue in sedentary HSCT recipients.

Adult↗
PubMed2004

Bicarbonate secretion plays a role in chloride and water absorption of the European flounder intestine.

Experiments performed on isolated intestinal segments from the marine teleost fish, the European flounder (Platichthys flesus), revealed that the intestinal epithelium is capable of secondary active HCO3(-) secretion in the order of 0.2-0.3 micromol x cm(-2) x h(-1) against apparent electrochemical gradient. The HCO3(-) secretion occurs via anion exchange, is dependent on mucosal Cl(-), results in very high mucosal HCO3(-) concentrations, and contributes significantly to Cl(-) and fluid absorption. This present study was conducted under in vivo-like conditions, with mucosal saline resembling intestinal fluids in vivo. These conditions result in a transepithelial potential of -16.2 mV (serosal side negative), which is very different from the -2.2 mV observed under symmetrical conditions. Under these conditions, we found a significant part of the HCO3(-) secretion is fueled by endogenous epithelial CO2 hydration mediated by carbonic anhydrase because acetazolamide (10(-4) M) was found to inhibit HCO3(-) secretion and removal of serosal CO(2) was found not to influence HCO3(-) secretion. Reversal of the epithelial electrochemical gradient for Cl(-) (removal of serosal Cl(-)) and elevation of serosal HCO3(-) resulted in enhanced HCO3(-) secretion and enhanced Cl(-) and fluid absorption. Cl(-) absorption via an anion exchange system appears to partly drive fluid absorption across the intestine in the absence of net Na(+) absorption.

Acetazolamide↗
PubMed2002

Binding and movement of silver in the intestinal epithelium of a marine teleost fish, the European flounder (Platichthys flesus).

The intestine has been indicated as a site of waterborne silver toxicity in marine fish and chronic effects at the intestine have been observed at concentrations far below acutely toxic level. Thus, models of silver toxicity to marine fish need to consider the intestine as a biotic ligand. The present study characterises binding of silver to the intestine of the European flounder (Platichthys flesus). Everted intestinal sacks were prepared and submersed in a solution mimicking the intestinal fluid of the fish at the acclimation salinity (21 per thousand). Silver was added as (110m)AgNO(3) or (110m)AgNO(3)/AgNO(3) mixtures at concentrations ranging from 1.6 to 950 nM total silver. Appearance of (110m)Ag was analysed in mucosal scrapings, muscle layers, and in the plasma saline on the serosal side of the intestine. The latter represented uptake into blood and other extra-intestinal compartments. Mucosal scrapings consisted of both epithelial cells and mucus and, thus contained adsorbed as well as absorbed silver. Most of the silver in mucosal scrapings was bound to mucus. There was no difference in silver binding between the anterior, mid, and posterior regions of the intestine. Concentration-dependency of silver binding was sigmoidal and saturated above 100 nM total silver. The saturable appearance of (110m)Ag in the plasma saline suggest that silver passage across the intestine is transcellular and carrier mediated. Mucus likely influences uptake of silver by altering its speciation from that in the lumen and by serving as physical barrier for silver binding to the brushborder membrane. A biotic ligand model for marine fish to silver may have to consider these interactions.

Animals↗
PubMed2001

Temporal and spatial profiling of the modification of an electroactive polymeric interface using neutron reflectivity.

Electropolymerized films of the functionalized pyrrole, pentafluorophenyl-3-(pyrrol-1-yl)propionate (PFP), were reacted with a solution-phase nucleophile, ferrocene ethylamine. This reaction was chosen as a model representative of a postdeposition modification of the polymer membrane's properties. For the first time, a nondestructive method for direct chemical analysis of the reaction profile within the electrodeposited polymer membrane after nucleophilic substitution is presented. This was achieved through the application of in situ neutron reflectivity with supplementary analytical information concerning the film's chemical composition obtained from XPS, FT-IR, and electrochemical measurements. The results presented illustrate how, for a partially reacted film resulting from a short reaction time, the extent of reaction with ferrocene ethylamine is not homogeneous throughout the thickness of the film, but occurs predominantly at the polymer/solution interface. We show that the progress of the reaction within the polymer film is limited by the transport of reacting species in the dense regions of the membrane that are furthest from the solution interface. The data do not fit an alternative model in which there is spatially homogeneous progression of the reaction front throughout the bulk of the thin film polymer. Guided by the neutron reflectivity measurements, suitable modifications were made to the electrodeposition method to prepare films whose architecture resulted in faster rates of reaction.

Journal Article↗
PubMed2001

Mycobacterium immunogenum sp. nov., a novel species related to Mycobacterium abscessus and associated with clinical disease, pseudo-outbreaks and contaminated metalworking fluids: an international cooperative study on mycobacterial taxonomy.

PCR-restriction enzyme pattern analysis of a 439 bp hsp65 gene segment identified 113 unique isolates among non-pigmented rapidly growing mycobacteria (RGM) from clinical and environmental sources that failed to match currently recognized species patterns. This group represented 40% of isolates recovered from bronchoscope contamination pseudo-outbreaks, 0% of disease-associated nosocomial outbreaks and 4% of routine clinical isolates of the Mycobacterium abscessus/Mycobacterium chelonae group submitted to the Mycobacteria/Nocardia laboratory for identification. It is grouped within the Mycobacterium fortuitum complex, with growth in less than 7 d, absence of pigmentation, positive 3-d arylsulfatase reaction and growth on MacConkey agar without crystal violet. It exhibited overlapping biochemical, antimicrobial susceptibility and HPLC characteristics of M. abscessus and M. chelonae. By 16S rRNA gene sequencing, these isolates comprised a homogeneous group with a unique hypervariable region A sequence and differed by 8 and 10 bp, respectively, from M. abscessus and M. chelonae. Surprisingly, this taxon contained two copies of the ribosomal operon, compared with single copies in the two related species. By DNA-DNA hybridization, this new group exhibited <30% homology with recognized RGM species. The name Mycobacterium immunogenum sp. nov. is proposed for this new taxon.

Bacterial Proteins↗
PubMed2001

Activities of linezolid against rapidly growing mycobacteria.

Linezolid is an oxazolidinone available as an oral drug which has activity against most gram-positive bacteria. However, few species of the genus Mycobacterium have been studied. We tested 249 clinical isolates and 10 reference strains of rapidly growing mycobacteria for susceptibility to linezolid by broth microdilution. Clinical species included the Mycobacterium fortuitum group (n = 74), M. abscessus (n = 98), M. chelonae (n = 50), M. mucogenicum (n = 10), and M. fortuitum third biovariant complex (10). The modal MIC for M. mucogenicum was 1.0 microg/ml, and the MIC at which 90% of the isolates tested are inhibited (MIC(90)) was 4 microg/ml; the modal MIC for the M. fortuitum group was 4 microg/ml, and the MIC(90) was 16 microg/ml; the modal MIC for the M. fortuitum third biovariant complex was 4 microg/ml, and the MIC(90) was 8 microg/ml; the modal MIC for M. chelonae was 8 microg/ml, and the MIC(90) was 16 microg/ml; and the modal MIC for M. abscessus was 32 microg/ml, and the MIC(90) was 64 microg/ml. Based on peak levels of linezolid in serum of 15 to 20 microg/ml, we propose the following broth MIC breakpoints for these species: susceptible, < or = 8 microg/ml; moderately susceptible, 16 microg/ml; and resistant, > or =32 microg/ml). These studies demonstrate the excellent potential of linezolid for therapy of rapidly growing mycobacteria.

Acetamides↗
PubMed2001

In vitro activities of linezolid against multiple Nocardia species.

Linezolid was tested by broth microdilution against 140 clinical Nocardia isolates belonging to seven species. The MIC at which 50% of the strains are inhibited (MIC50) and MIC90 for all species other than Nocardia farcinica were 2 and 4 microg/ml. Linezolid is the first antimicrobial agent demonstrated to be active against all Nocardia species.

Acetamides↗
PubMed2001

Intestinal iron uptake in the European flounder (Platichthys flesus).

Iron is an essential element because it is a key constituent of the metalloproteins involved in cellular respiration and oxygen transport. There is no known regulated excretory mechanism for iron, and homeostasis is tightly controlled via its uptake from the diet. This study assessed in vivo intestinal iron uptake and in vitro iron absorption in a marine teleost, the European flounder Platichthys flesus. Ferric iron, in the form (59)FeCl(3), was reduced to Fe(2+) by ascorbate, and the bioavailability of Fe(3+) and Fe(2+) were compared. In vivo Fe(2+) uptake was significantly greater than Fe(3+) uptake and was reduced by the iron chelator desferrioxamine. Fe(2+) was also more bioavailable than Fe(3+) in in vitro studies that assessed the temporal pattern and concentration-dependency of iron absorption. The posterior region, when compared with the anterior and mid regions of the intestine, was the preferential site for Fe(2+) uptake in vivo. In vitro iron absorption was upregulated in the posterior intestine in response to prior haemoglobin depletion of the fish, and the transport showed a Q(10) value of 1.94. Iron absorption in the other segments of the intestine did not correlate with haematocrit, and Q(10) values were lower. Manipulation of the luminal pH had no effect on in vitro iron absorption. The present study demonstrates that a marine teleost absorbs Fe(2+) preferentially in the posterior intestine. This occurs in spite of extremely high luminal bicarbonate concentrations recorded in vivo, which may be expected to reduce the bioavailability of divalent cations as a result of the precipitation as carbonates (e.g. FeCO(3)).

Animals↗
PubMed2000

Effects of pre-acclimation to aluminium on the physiology and swimming behaviour of juvenile rainbow trout (Oncorhynchus mykiss) during a pulsed exposure.

Anthropogenic acidification of the freshwater environment causes aluminium to be mobilised into the aquatic environment. When pH falls below 5.5, exposure to aluminium concentrations as low as 12.5 microg.l(-1) can cause serious physiological disturbances in freshwater fish. However, under constant laboratory exposures fish can acclimate and recover physiological status within 5-30 days. In reality, fish in the wild are likely to experience chronic sub-lethal exposure, with occasional elevations (pulses) to much higher levels. The experiment described here investigated the effects of an environmentally realistic, 4-day pulse exposure to a high level of aluminium (36 microg.l(-1)) in two groups of juvenile rainbow trout. One group was exposed to a lower level of aluminium (24 microg.l(-1)) for 16 days before and 10 days after the pulse ('aluminium-acclimated' fish). A second group was exposed to pH 5.2 alone for 16 days before and 10 days after the pulse ('aluminium-naïve' fish). A third group exposed to pH 5.2 alone for 30 days (no aluminium added) acted as controls. Triplicate groups of 24 juvenile rainbow trout (2.3-16.7 g) were randomly allocated to one of these three treatments. Swimming behaviour was monitored throughout and samples were taken on days 14, 20, 22, 26 and 30 for assessment of physiological status. No treatment effects were recorded in the control group (pH 5.2 alone). Fish in the 'aluminium-acclimated' treatment became hypo-active upon initiation of the exposure to 24 microg.l(-1) aluminium, but recovered after just 4 days of this exposure. Subsequent challenge on day 16 with the 36 microg.l(-1) aluminium 'pulse' caused these fish to became hypo-active again, but they recovered normal swimming behaviour whilst still subject to the 4-day pulse. The 'aluminium-naïve' fish also became hypo-active during the pulse exposure (36 microg.l(-1) aluminium). However, they did not exhibit any recovery of swimming behaviour, either during the pulse, or even 6 days after the cessation of the pulse, despite a rapid depuration of gill aluminium load (within 2 days of the pulse finishing). Mortality was low in the aluminium-acclimated fish (4%) and significantly higher in the aluminium-naïve fish (26%). Haematological disturbances were most extreme in the aluminium-naïve fish and had not recovered to control levels 6 days after the end of the pulse. This study provides new evidence, using behavioural responses, that previous exposure to low levels of aluminium may be an important factor abating the impact of aluminium on fish in the natural environment.

Adaptation, Physiological↗
PubMed2000

Long-term results of permanent indwelling wallstents for benign mid-ureteral strictures.

BACKGROUND: Benign ureteral strictures are a potentially difficult problem that typically has been solved by open surgery. However, minimally invasive methods would be preferable. PATIENTS AND METHODS: Three patients with benign ureteral strictures were treated with endoscopic placement of self-expanding permanent indwelling stents (Wallstents). The etiologies of the obstruction were multifactorial and included retroperitoneal fibrosis, stones, traumatic ureteroscopy, ureteral ischemia, and previous open surgery. RESULTS: One patient died with a functioning stent 1 year, 7 months after placement. The other two patients are doing well 5 years, 2 months and 5 years, 11 months afterward (mean 51 months). CONCLUSION: Insertion of a permanent indwelling self-expanding ureteral stent is relatively easy, and long-term successes are documented. Placement of Wallstents for benign ureteral strictures should be considered as a treatment alternative.

Aged↗
PubMed2000

Measures of functional limitation as predictors of disablement in athletes with acute ankle sprains.

STUDY DESIGN: Prospective multivariate design. OBJECTIVES: To determine the usefulness of activity scores, self-reported athletic ability, and selected measures of physical impairment as predictors of disability duration in athletes with ankle inversion sprains. BACKGROUND: Although several measures of physical impairment and functional limitation are used to assess the consequences of injury following ankle sprain, researchers have yet to establish which measures provide the most accurate predictions of disability duration. METHODS AND MEASURES: Physical impairment, activity limitation, and disability duration were measured in 21 athletes (13 men and 8 women; mean age = 20.3 +/- 1.7 years) with acute ankle sprains. Sagittal plane ankle range of motion and volumetric displacement were used as impairment indicators. Weight-bearing activity scores (task completion count) and self-reported athletic ability (visual analog scale) were used to represent functional limitation. Elapsed time from injury to return to full athletic participation was used as the criterion measure of disability duration. RESULTS: The impairment measures accounted for approximately one-third of the variance in disability duration (R2 = 0.342). Adding the activity limitation measures to the regression model improved predictions of disability duration (R2 = 0.670; stepwise R2 change = 0.328). The measures of activity limitation alone, however, accounted for approximately 67% (R2 = 0.665) of the total variance in the number of days lost due to injury. CONCLUSION: Measures of activity limitation were the strongest predictors of elapsed time from injury to return to full athletic participation.

Absenteeism↗
PubMed1999

Prevalence of sexual and drug-related HIV risk behaviors in the U.S. adult population: results of the 1996 National Household Survey on Drug Abuse.

CONTEXT: Data on the prevalence of HIV risk behavior that are representative of the general population are needed to help evaluate the effectiveness of prevention programs. OBJECTIVE: To use data from a large national interview survey to make estimates of the prevalence of sexual and drug-related HIV risk behaviors in the adult population of the United States. DESIGN: Nationally representative cross-sectional survey with in-person interviews collecting information on drug use and sexual behavior. SETTING AND PARTICIPANTS: 12,381 U.S. adults aged between 18 and 59 who were respondents to the 1996 National Household Survey on Drug Abuse, as part of sample of the noninstitutionalized population. Interviews took place in respondents homes using face-to-face interviewer-administered and self-administered questionnaires. RESULTS: In total, 2.8% of respondents were classified as having increased risk for HIV through sexual behavior; this represents 3.9 million persons. 1.7% reported some degree of risk through drug-related behaviors, representing 1.2 million persons. 3.5% of adults (5 million persons) were found to have some degree of HIV risk from sexual or drug-related behavior. Persons who were at risk through drug behavior were much more likely than others to be at risk through sexual behavior. Condom use was not related to HIV risk, although having a recent HIV test was found to be. Among those who reported some behaviors that placed them at increased risk for HIV infection, only 22% used a condom the last time they had sex with a regular partner. CONCLUSIONS: The high rate of sexual risk behavior on the part of drug users suggests increasing condom use for this group should be a priority goal for programs, especially condom use with main partners. Survey work needs to be continued and improved to make it possible to assess the impact of successful local prevention efforts on national rates of HIV risk behavior.

Adolescent↗