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Biomedical subjects

J Lyons

Publications and source records attributed to J Lyons.

At least 19 recordsLinked to original sources
PubMed2006

Influence of endogenous and exogenous orientations of attention on inhibition of return in a cross-modal target-target aiming task.

The authors conducted 2 experiments in which participants (N = 16 in each) executed successive unimanual aiming movements to target locations that were indicated by the onset of either an auditory or a visual stimulus. In Experiment 1 (exogenous orientation), inhibition of return (IOR) effects were observed, with reliable reaction time (RT) costs associated with movements returning to the same target and a trend toward larger IOR effects in left than in right space. There was no influence of stimulus modality on the magnitude of IOR. IOR was also observed in Experiment 2 (endogenous orientation), except the influence of stimulus modality reliably mediated those effect. In that case, IOR was evident only when the previous modality was visual and the current modality was auditory. Together, the results of those 2 experiments suggest that in situations in which 2 paired movements constitute the response criteria, IOR is both supramodal and lateralized to contralateral space.

Acoustic Stimulation↗
PubMed2004

Influence of forest machine function on operator exposure to whole-body vibration in a cut-to-length timber harvester.

The influence of machine function (tree felling and processing, and machine movement over the terrain) on operator exposure to whole-body vibration in a cut-to-length (CTL) timber harvester was evaluated. Vibrations were measured on the seat and the cabin chassis in three orthogonal (x, y, z) axes for the tree felling and processing, and during motion on a test track. It was found that the level of vibration transmitted to the operator during felling and processing was mainly affected by the tree size (diameter). For tree diameter at breast height (dbh) range of 0.25-0.35 m that was investigated, the vertical (z-axis) vibration component during processing increased by up to 300%, and increased by 50% during felling. However, the associated vibration levels were not sufficient to pose any serious health risks to the operator for an exposure limit of 8 h. Vibration at the operator seat and cabin chassis was predominant in the lateral (y-axis) and vertical (z-axis) respectively, during vehicle motion over the standard test track. Vibration peaks of approximately 0.20 and 0.17 ms(-2) occurred at 5 and 3.2 Hz respectively.

Air Pressure↗
PubMed2004

Influence of tyre inflation pressure on whole-body vibrations transmitted to the operator in a cut-to-length timber harvester.

The influence of tyre inflation pressure on whole-body vibrations transmitted to the operator during the movement of a cut-to-length timber harvester was evaluated. Vibration measurements were taken in three orthogonal (x, y, z) axes at tyre pressure settings of 138, 345 and 414 kPa. Vibration was predominant in the vertical (z) direction with the peak rms acceleration value for the operator seat (0.281 ms(-2)) occurring at approximately 3.2 Hz. The corresponding peak value for the operator cabin chassis was 0.425 m s(-2) at 4 Hz. At 414 kPa, there was potential health risk on the operator for exposures above 8h duration. The vibration total values recorded for the operator seat at the maximum tyre inflation pressure setting were classed as "fairly uncomfortable" (ISO standard 2631-1), and vertical seat vibration transmissibility was highest between 4 and 8 Hz at the 345 kPa tyre pressure setting. The recorded values of WBV were significantly reduced by a reduction in tyre inflation pressure which may therefore be used to moderate the magnitude of WBV on wheeled timber harvesters.

Air Pressure↗
PubMed2003

Influence of terminal action requirements on action-centered distractor effects.

Tipper (1985; Q J Exp Psychol A 37:571-590) has suggested that competing responses programmed to distracting stimuli are inhibited based on their relationship to the action being performed. The present paper reports two experiments designed to examine the influence of the terminal action of a task on the allocation of visual attention. Taken together the results suggest that when engaging targets in an environment, which includes distracting stimuli, competing responses are likely to be programmed in parallel and that the relationship between competing responses can include both spatial position and action characteristics.

Adult↗
PubMed2003

Testing the effectiveness of techniques for reducing heat strain in Royal Navy nuclear, biological and chemical cleansing stations' teams.

Nine personnel simulating the work of an NBC cleansing station (CS) in conditions expected in Middle Eastern waters had a limited work duration due to incapacitating heat strain. When the subjects were allowed five minutes rest periods after every 10 minutes of work, the endurance of seven of the subjects was limited to between 75-105 minutes due to heat strain and heat illness. By the point of withdrawal mean (SD) rectal temperature (Tre) had risen by 1.8 degrees C (0.4 degree C). The other two subjects were withdrawn earlier because they reached cardiac safety limits. When the hands were immersed (HI) in 10 degrees C water during the five minute rest periods heat strain was significantly lower (P < 0.01) and work endurance times were increased. One subject was withdrawn early on reaching cardiac safety limits, two on reaching Tre limits (39 degrees C) at 105 minutes, and six subjects completed the 180 minute exposure with a final Tre of 38.4 degrees C (0.3 degree C). Using 'iced' (0 degree C) rather than 10 degrees C water for HI further reduced heat strain (P < 0.01) and increased endurance times. Three subjects were withdrawn early on reaching cardiac safety limits, the remaining six completing the 180 minute exposure, with a final Tre of 38.3 degrees C (0.5 degree C). Using an ice-vest (IV) in conjunction with HI further reduced heat strain (P < 0.01) and increased endurance times. Two subjects were withdrawn early on reaching cardiac safety limits, the remaining seven completing the 180 minute exposure, with a final Tre of 38.2 degrees C (0.8 degree C) when 10 degrees C HI water was used, and Tre 38.0 degrees C (0.4 degree C) when 0 degree C HI water was used. There were no reports of finger numbness or loss of dexterity due to HI, and all personnel were able to remove their own individual Protective Equipment (IPE) without difficulty. It is expected that using HI will not reduce the ability to decontaminate or undress others. The HI technique and IV equipment should be introduced into the Fleet. 'Iced' water should be used in preference to 10 degrees C, although any water colder than 25 degrees C will provide some benefit. The IVs increased torso girth and personnel should try them on (with frozen ice packs inserted) prior to their use and ensure that their protective clothing still fits, or obtain a larger size.

Body Temperature↗
PubMed2001

Discovery of heterocyclic ureas as a new class of raf kinase inhibitors: identification of a second generation lead by a combinatorial chemistry approach.

Heterocyclic ureas, such as N-3-thienyl N'-aryl ureas, have been identified as novel inhibitors of raf kinase, a key mediator in the ras signal transduction pathway. Structure-activity relationships were established, and the potency of the screening hit was improved 10-fold to IC(50)=1.7 microM. A combinatorial synthesis approach enabled the identification of a breakthrough lead (IC(50)=0.54 microM) for a second generation series of heterocyclic urea raf kinase inhibitors.

Proto-Oncogene Proteins c-raf↗
PubMed2001

B cells and antibodies in CNS demyelinating disease.

There is much evidence to implicate B cells, plasma cells, and their products in the pathogenesis of MS. Despite unequivocal evidence that the animal model for MS, EAE, is initiated by myelin-specific T cells, there is accumulating evidence of a role for B cells, plasma cells, and their products in EAE pathogenesis. The role(s) played by B cells, plasma cells, and antibodies in CNS inflammatory demyelinating diseases are likely to be multifactorial and complex, involving distinct and perhaps opposing roles for B cells versus antibody.

Animals↗
PubMed2001

Impacts of urbanization on stream habitat and fish across multiple spatial scales.

We analyzed the relation of the amount and spatial pattern of land cover with stream fish communities, in-stream habitat, and baseflow in 47 small southeastern Wisconsin, USA, watersheds encompassing a gradient of predominantly agricultural to predominantly urban land uses. The amount of connected impervious surface in the watershed was the best measure of urbanization for predicting fish density, species richness, diversity, and index of biotic integrity (IBI) score; bank erosion; and base flow. However, connected imperviousness was not significantly correlated with overall habitat quality for fish. Nonlinear models were developed using quantile regression to predict the maximum possible number of fish species, IBI score, and base flow for a given level of imperviousness. At watershed connected imperviousness levels less than about 8%, all three variables could have high values, whereas at connected imperviousness levels greater than 12% their values were inevitably low. Connected imperviousness levels between 8 and 12% represented a threshold region where minor changes in urbanization could result in major changes in stream condition. In a spatial analysis, connected imperviousness within a 50-m buffer along the stream or within a 1.6-km radius upstream of the sampling site had more influence on stream fish and base flow than did comparable amounts of imperviousness further away. Our results suggest that urban development that minimizes amount of connected impervious surface and establishes undeveloped buffer areas along streams should have less impact than conventional types of development.

Agriculture↗
PubMed2001

Cysteine metabolism and whole blood glutathione synthesis in septic pediatric patients.

OBJECTIVE: To investigate whole body in vivo cysteine kinetics and its relationship to whole blood glutathione (GSH) synthesis rates in septic, critically ill pediatric patients and controls. DESIGN: Prospective cohort study. SETTING: Multidisciplinary intensive care unit and pediatric inpatient units at a children's hospital. PATIENTS: Ten septic pediatric patients and ten controls (children admitted to the hospital for elective surgery). INTERVENTIONS: Septic patients (age, 31 months to 17 yrs) and controls (age, 24 months to 21 yrs) received a 6-hr primed, constant, intravenous tracer infusion of l-[1-13C]cysteine. Blood samples were obtained to determine isotopic enrichment of plasma cysteine and whole blood [1-13C]cysteinyl-glutathione by gas-chromatography mass spectrometric techniques. The plasma flux and oxidation rate of cysteine and the fractional and absolute synthesis rates of GSH were determined. Septic patients received variable protein and energy intake, as per routine clinical management, and controls were studied in the early postabsorptive state. MEASUREMENTS AND MAIN RESULTS: Plasma cysteine fluxes were increased in the septic patients when compared with the controls (68.2 +/- 17.5 [sd] vs. 48.7 +/- 8.8 micromol x kg(-1) x hr(-1); p <.01), and the fraction of plasma cysteine flux associated with oxidative disposal was similar among the groups. The absolute rates of GSH synthesis in whole blood were decreased (p <.01) in the septic patients (368 +/- 156 vs. 909 +/- 272 micromol x L(-1) x day(-1)). The concentration of whole blood GSH also was decreased in the septic group (665.4 +/- 194 vs. 1059 +/- 334 microM; p <.01) CONCLUSIONS: Whole blood glutathione synthesis rates are decreased, by about 60%, in critically ill septic children receiving limited nutritional support. Plasma cysteine fluxes and concentration of cysteine were increased in the septic patients, suggesting a hypermetabolic state with increased protein breakdown. The mechanisms whereby GSH synthesis rates are decreased in these patients are probably multifactorial, presumably involving an inflammatory response in the presence of limited nutritional support. The role of nutritional modulation and the use of cysteine prodrugs in maintaining GSH concentration and synthesis remain to be established.

Adolescent↗
PubMed2001

Clinical characteristics of youths with substance use problems and implications for residential treatment.

OBJECTIVE: Despite high rates of dual diagnosis among children and adolescents and evidence that adults with coexisting substance use disorders require specialized services, many children are placed in residential settings and are offered uniform service packages regardless of their individual clinical profiles. The authors examined the rate of substance use problems in a sample of children and adolescents with severe emotional or behavioral disturbances who were in residential treatment. Differences in clinical characteristics and placement outcomes between children with and without coexisting substance use disorders were evaluated. METHODS: This retrospective study analyzed clinical data obtained by chart review using the Child Severity of Psychiatric Illness, a rating scale for symptom severity. The study subjects were 564 children and adolescents in residential treatment and state custody in Florida and Illinois who had serious emotional or behavioral disturbances. RESULTS: Twenty-six percent of boys and 37 percent of girls had substance use problems in addition to serious emotional or behavioral disturbances. Residents with co-occurring substance use disorders were significantly more likely than those with serious emotional or behavioral disturbances only to be at risk for suicide, elopement from residential placement, delinquent behavior, and institutional discharge placement. CONCLUSIONS: Children and adolescents with coexisting substance use problems require individualized service packages to address their greater need for supervision and higher rate of risk behaviors and to facilitate community discharge placements.

Adolescent↗
PubMed2000

Blood glutathione synthesis rates in healthy adults receiving a sulfur amino acid-free diet.

The availability of cysteine is thought to be the rate limiting factor for synthesis of the tripeptide glutathione (GSH), based on studies in rodents. GSH status is compromised in various disease states and by certain medications leading to increased morbidity and poor survival. To determine the possible importance of dietary cyst(e)ine availability for whole blood glutathione synthesis in humans, we developed a convenient mass spectrometric method for measurement of the isotopic enrichment of intact GSH and then applied it in a controlled metabolic study. Seven healthy male subjects received during two separate 10-day periods an L-amino acid based diet supplying an adequate amino acid intake or a sulfur amino acid (SAA) (methionine and cysteine) free mixture (SAA-free). On day 10, L-[1-(13)C]cysteine was given as a primed, constant i.v. infusion (3 micromol x kg(-1) x h(-1)) for 6 h, and incorporation of label into whole blood GSH determined by GC/MS selected ion monitoring. The fractional synthesis rate (mean +/- SD; day(-1)) of whole blood GSH was 0.65 +/- 0.13 for the adequate diet and 0.49 +/- 0.13 for the SAA-free diet (P < 0.01). Whole blood GSH was 1,142 +/- 243 and 1,216 +/- 162 microM for the adequate and SAA-free periods (P > 0.05), and the absolute rate of GSH synthesis was 747 +/- 216 and 579 +/- 135 micromol x liter(-1) x day(-1), respectively (P < 0.05). Thus, a restricted dietary supply of SAA slows the rate of whole blood GSH synthesis and diminishes turnover, with maintenance of the GSH concentration in healthy subjects.

Adult↗
PubMed2000

Higher than standard radiation doses (> or =72 Gy) with or without androgen deprivation in the treatment of localized prostate cancer.

PURPOSE: To study the effect on biochemical relapse-free survival (bRFS) and clinical disease-free survival of radiation doses delivered to the prostate and periprostatic tissues for localized prostate cancer. METHODS AND MATERIALS: A total of 1041 consecutive localized prostate cancer cases treated with external beam radiotherapy (RT) at our institution between 7/86 and 2/99 were reviewed. All cases had available pretreatment parameters including pretreatment prostate-specific antigen (iPSA), biopsy Gleason score (bGS), and clinical T stage. The median age was 69 years. Twenty-three percent of cases (n = 238) were African-American. The distribution by clinical T stage was as follows: T1 in 365 cases (35%), T2 in 562 cases (54%), and T3 in 114 cases (11%). The median iPSA level was 10.1 ng/ml (range: 0.4-692.9). The distribution by biopsy Gleason score (bGS) was as follows: < or =6 in 580 cases (56%) and > or =7 in 461 cases (44%). Androgen deprivation (AD) in the adjuvant or neoadjuvant setting was given in 303 cases (29%). The mean RT dose was 71.9 Gy (range: 57.6-78.0 Gy). The median RT dose was 70.2 Gy, with 458 cases (44%) receiving at least 72.0 Gy. The average dose in patients receiving <72 Gy was 68.3 Gy (median 68.4) versus 76.5 Gy (median 78.0) for patients receiving > or =72 Gy. The mean follow-up was 38 months (median 33 months). The number of follow-up prostate-specific antigen (PSA) levels available was 5998. RESULTS: The 5- and 8-year bRFS rates were 61% (95% CI 55-65%) and 58% (95% CI 51-65%), respectively. The 5-year bRFS rates for patients receiving radiation doses > or =72 Gy versus <72 Gy were 87% (95% CI 82-92%) and 55% (95% CI 49-60%), respectively. The 8-year bRFS rates for patients receiving radiation doses > or =72 Gy versus <72 Gy were 87% (95% CI 82-92%) and 51% (95% CI 44-58%), respectively (p < 0.001). A multivariate analysis of factors affecting bRFS was performed using the following parameters: age (continuous variable), race, T-stage (T1-T2 vs. T3), iPSA (continuous variable), bGS (< or =6 vs. > or =7), use of AD (yes vs. no), radiation technique (conformal versus standard), and radiation dose (continuous variable). T-stage (p < 0.001), iPSA (p < 0.001), bGS (p < 0.001), and RT dose (p < 0.001) were independent predictors of outcome. Age (p = 0.74), race (p = 0.96), radiation technique (p = 0.15), and use of AD (p = 0.31) were not. We observed 11% clinical failures (local, distant, or both) at 5 years and 15% at 8 years for the entire cohort. There was a statistically significant improvement with higher radiation doses (p = 0.032). The 5-year clinical relapse rates for patients receiving > or =72 Gy versus <72 Gy were 5% and 12%, respectively. The 8-year clinical relapse rates for patients receiving radiation doses > or =72 Gy versus <72 Gy were 5% and 17%, respectively (p = 0.026). CONCLUSION: Patients receiving radiation doses exceeding 72 Gy had significantly better bRFS and clinical disease-free survival rates. Although results need to be confirmed with longer follow-up, these preliminary results are extremely encouraging. If these results are confirmed by other institutions and by longer follow-up, RT doses exceeding 72 Gy should be considered as standard of care.

Aged↗
PubMed2000

Needs for oral care among people with intellectual disability not in contact with Community Dental Services.

Previous research has found an unmet need for oral care among people with intellectual disability. The key factors which have been indicated are low expectations, fear of treatment, lack of awareness among carers and problems in accessing dental services. The withdrawal of many general dental practitioners (GDPs) from the National Health Service (NHS) may have exacerbated the latter problem in the UK. The aims of the present study were: (1) to assess the extent of unmet clinical needs in a group of adults with intellectual disability living in the community who were not in contact with the Community Dental Service (CDS); and (2) to explore their perceptions of teeth and contact with dentists to identify how oral care can be improved. Interviews were completed with subjects and/or carers and a dental examination was completed. There were higher levels of untreated caries (decay), and gingival or periodontal (gum) problems among the sample than in either the general population, or in a previous survey of CDS users at day centres and residential facilities. The subjects were largely unaware of dental problems, and used the appearance and absence of pain to judge the condition of their teeth. They depended greatly on their carers for decision-making and support with regard to visiting the dentist and tooth-brushing. Carers requested training in oral care and the use of dental services, and support in dealing with clients who have problems tolerating tooth-brushing. The subjects had experienced a wide variation in the treatment provided by dentists, but had not found it difficult to access a dentist despite recent reductions in the availability of NHS dental care. They expressed a particular need for a good relationship with their dentist and for their dentist to have personal skills in relating to people with an intellectual disability. Dental screening checks and oral care training for carers should be made easily available. Care plans should include tooth-brushing and dietary issues for all clients who have their own natural teeth. There are significant training issues for dentists in developing personal skills in total communication, disability awareness and attitudes which value people with intellectual disability.

Adult↗
PubMed2000

Arginine, citrulline, and nitric oxide metabolism in end-stage renal disease patients.

The kidneys are thought to be a major site of net de novo arginine synthesis, but the quantitative status of arginine metabolism and its substrate precursor relationship to nitric oxide (NO) synthesis in end stage renal disease (ESRD) patients have not been characterized. We have investigated kinetic aspects of whole body arginine metabolism in six patients with ESRD. They received two pre- and two post-hemodialysis intravenous tracer infusion studies with L-[guanidino-(15)N(2)]arginine and L-[(13)C]leucine during the first study, and L-[5-(13)C]arginine and L-[5-(13)C-ureido,5,5, (2)H(2)]citrulline during the second study. Arginine homeostasis in ESRD patients was found to be associated with a lower rate of arginine oxidation, and despite the decrease in renal function, the rate of de novo arginine synthesis appeared to be preserved. Plasma citrulline concentrations and flux were also elevated in these subjects compared with healthy adults. The rate of whole body NO synthesis was increased in the ESRD patients, but apparently not different pre- and post-hemodialysis therapy. The anatomic site(s) responsible for the maintenance of net de novo arginine synthesis and for the elevated NO synthesis and its pathophysiological importance in ESRD remain to be established.

Adult↗