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R Jones

Publications and source records attributed to R Jones.

At least 73 records · Page 4Linked to original sources
PubMed2003

Interaction of normal and expanded CAG repeat sizes influences age at onset of Huntington disease.

Huntington disease (HD) is a neurodegenerative disorder caused by the abnormal expansion of CAG repeats in the HD gene on chromosome 4p16.3. Past studies have shown that the size of expanded CAG repeat is inversely associated with age at onset (AO) of HD. It is not known whether the normal Huntington allele size influences the relation between the expanded repeat and AO of HD. Data collected from two independent cohorts were used to test the hypothesis that the unexpanded CAG repeat interacts with the expanded CAG repeat to influence AO of HD. In the New England Huntington Disease Center Without Walls (NEHD) cohort of 221 HD affected persons and in the HD-MAPS cohort of 533 HD affected persons, we found evidence supporting an interaction between the expanded and unexpanded CAG repeat sizes which influences AO of HD (P = 0.08 and 0.07, respectively). The association was statistically significant when both cohorts were combined (P = 0.012). The estimated heritability of the AO residual was 0.56 after adjustment for normal and expanded repeats and their interaction. An analysis of tertiles of repeats sizes revealed that the effect of the normal allele is seen among persons with large HD repeat sizes (47-83). These findings suggest that an increase in the size of the normal repeat may mitigate the expression of the disease among HD affected persons with large expanded CAG repeats.

Adolescent↗
PubMed2003

Z1/Z2 defects in 4H-SiC.

First-principles calculations are carried out on models for the Z(1)/Z(2) defects in 4H-SiC which are found in as-grown and irradiated n-type material. We show that an interstitial-nitrogen-interstitial-carbon defect is exceptionally thermally stable, bistable, and has negative-U character with donor and acceptor levels close to those attributed to the defect.

Journal Article↗
PubMed2003

Environmental benefits and economic costs of manure incorporation on dairy waste application fields.

Model simulations performed representing dairies in a 93000 ha watershed in north central Texas suggest that manure incorporation results in reduced phosphorus (P) losses at relatively small to moderate cost to producers. Simulated manure incorporation with a tandem disk on fields double-cropped with sorghum/winter wheat resulted in up to 33, 45, and 37% reductions in per hectare sediment-bound, soluble, and total P losses in edge-of-field runoff, relative to simulated surface manure applications. The effects of incorporation were evaluated at three different manure application rates. On aggregate across all three manure application rates, significant declines in P losses were obtained with incorporation except for sediment-bound P losses under the N-based manure application rate scenario. We found that the practice of incorporating manure shortly after it has been broadcast on the soil surface could help reduce P losses in such situations where P-based rates alone prove inadequate. The cost the producer incurs when manure is incorporated is on average about 1% of net returns when manure is applied at the N rate and 2-3% when it is applied at alternative P-based rates. In practice the costs could be lower because producers may substitute the manure incorporation operation for a tandem disk operation performed prior to manure application. As more and more dairy producers switch to the use of sorghum and corn silage in dairy rations and consequent on-farm production of these forages, the practice of manure incorporation may help to reduce phosphorus losses resulting from dairy manure applications to fields with these forage crops.

Animals↗
PubMed2003

Evaluation of trajectories and contact pressures for the straight nucleus cochlear implant electrode array - a two-dimensional application of finite element analysis.

A two-dimensional (2D) finite element analysis has been used in this study to model the insertion of the Nucleus electrode array with different stiffness properties in order to evaluate the propensity of damage by visualizing the predicted trajectories and by comparing the buckling stresses and the contact pressures at the tip (and its distribution along the length) of the electrode array. Previous temporal bone studies have shown that damage during insertion of an electrode array around the basal turn of the cochlear spiral could be related to the design and the stiffness properties of the electrode array. However, it is difficult to evaluate different designs of electrode arrays purely by experimental methods as the experimental conditions and their results are difficult to reproduce. Three electrode arrays with different mechanical properties, i.e. uniform stiffness, graded stiffness, and a soft tip have been modelled. Buckling stress and contact pressure at the tip of the electrode array were found to be highest for the arrays with uniform stiffness. The contact pressures at the tip of the electrode array appeared strongly influenced by the stiffness profile and were optimal for graded stiffness. The results indicate the importance of the electrode array design and stiffness properties in minimizing trauma. However, there are a number of limitations in the present 2D evaluation which will require further analysis using a three-dimensional model to obtain definitive results.

Cochlea↗
PubMed2003

Wound and injury awareness amongst students and doctors.

INTRODUCTION: Concern has been raised in the medical press regarding the inability of doctors to describe wounds and injuries of medico-legal significance correctly. METHODS: Medical students and doctors of all grades, from the Department of Surgery at a London teaching-hospital affiliated unit were shown a series of photographs illustrating wounds and injuries expected to be encountered in emergency medical practice. They were asked to identify the type of wound or injury as well as the manner in which that injury may have been caused. RESULT: The results indicated that students and doctors of all grades in this unit were not confident at identifying wounds and injuries, using the correct terminology. The term 'laceration' was widely used to describe incised wounds, and vice versa. Gun shot wounds were poorly identified as such, and were only correctly described by those who clearly 'knew' what they were looking at. CONCLUSION: In order to provide doctors with the skills with which they need to correctly describe wounds and injuries encountered in an emergency setting, this author proposes the introduction of specific teaching in wound identification at undergraduate and postgraduate levels.

Journal Article↗
PubMed2003

The effect of motilin on the rectum in healthy volunteers.

AIMS: The role of motilin in the regulation of upper gastrointestinal (GI) motility is well defined. However, little is known about the effects on the distal GI tract. To investigate the effect of exogenous motilin on rectal function, barostat measurements in the rectum were performed and lower abdominal symptoms were scored. METHODS: Eight fasted, healthy volunteers were infused intravenously with synthetic motilin or placebo over 90 min in a double-blind, randomized, cross-over design. Rectum volume was measured with a barostat device during constant pressure and during isobaric distensions. Lower abdominal symptoms were scored by visual analogue scales. Plasma motilin concentrations were measured by radioimmunoassay. RESULTS: Baseline rectum volumes were similar between treatments: 185 +/- 62 mL (motilin) and 136 +/- 41 mL (placebo). During the constant pressure procedure, motilin increased rectum volume [area under the effect curve (AUEC)] by 6%[95% confidence interval (CI) -3, 16] of baseline, compared with placebo. During isobaric distensions motilin increased rectum volume (AUEC) by 43 mL (95% CI 0.4, 85; P < 0.05) and compliance by 10 mL mmHg-1 (95% CI 0.3, 20; P < 0.05) relative to placebo. Motilin did not induce changes in the sensation of rectal feelings. CONCLUSION: Exogenous motilin increased rectal compliance in healthy volunteers, without affecting rectal sensations.

Adult↗
PubMed2003

Improving primary orthopaedic and trauma care in Nepal.

PURPOSE: To evaluate the efficacy of training programmes for the village health practitioners aimed at improving primary orthopaedic and trauma care in our rural setting. MATERIALS & METHODS: Six year prospective study of training workshops in local health institutions was carried out using locally available manpower and materials. RESULTS: After 6 years the evaluation of this programme shows a significantly improved (p < 0.05) knowledge base and working skills after completion of training workshop. SUMMARY: To avoid unnecessary complications, effective primary health care provided by an appropriately trained person should be available at the peripheral level. This training programme seems successful in achieving this goal and hence needs adoption for wider use in Nepal.

Community Health Workers↗
PubMed2003

Molecular characterization of fluoroquinolone-resistant Campylobacter spp. isolated from poultry.

Campylobacteriosis, an infectious disease caused by Campylobacter jejuni and Campylobacter coli, is treated by fluoroquinolone antibiotics in clinical practices. However, use of these drugs in animal husbandry may select for fluoroquinolone-resistant campylobacters and, thereby, compromise the clinical treatment of infection. In this study, 21 fluoroquinolone-resistant campylobacters were isolated from poultry samples. Morphological and biochemical characteristics indicated that 19 isolates were C. jejuni and two were C. coli. All isolates were resistant to multiple antibiotics but sensitive to chloramphenicol and gentamicin. These isolates were characterized at the molecular level by amplifying the flagellin gene (flaA) by PCR. The PCR protocol amplified a 1.7-kb flaA gene from all isolates. RFLP analysis of the 1.7-kb amplicons after digestion with DdeI yielded four distinct patterns. The 21 fluoroquinolone-resistant campylobacter isolates were further characterized by pulsed-field gel electrophoresis (PFGE) and compared with the PFGE patterns of nine fluoroquinolone-sensitive campylobacter strains. Four of the 21 fluoroquinolone-resistant isolates were untypable by the PFGE protocol. The PFGE analysis with SalI or SmaI indicated that seven or five, respectively, of the 17 resistant isolates had identical macrorestriction profiles (mrps). However, PFGE analysis with a combination of SalI and SmaI indicated that four of the 17 isolates had similar macrorestriction profiles. The PFGE patterns of the 17 fluoroquinolone-resistant isolates were different from the nine sensitive campylobacter strains.

Animals↗
PubMed2003

Molecular characterization of gentamicin-resistant Enterococci in the United States: evidence of spread from animals to humans through food.

We evaluated the molecular mechanism for resistance of 360 enterococci for which the gentamicin MICs were >/=128 micro g/ml. The aac(6')-Ie-aph(2")-Ia, aph(2")-Ic, and aph(2")-Id genes were identified by PCR in isolates from animals, food, and humans. The aph(2")-Ib gene was not identified in any of the isolates. Two Enterococcus faecalis isolates (MICs > 1,024 micro g/ml) from animals failed to generate a PCR product for any of the genes tested and likely contain a new unidentified aminoglycoside resistance gene. Pulsed-field gel electrophoresis (PFGE) analysis showed a diversity of strains. However, 1 human and 18 pork E. faecalis isolates from Michigan with the aac(6')-Ie-aph(2")-Ia gene had related PFGE patterns and 2 E. faecalis isolates from Oregon (1 human and 1 grocery store chicken isolate) had indistinguishable PFGE patterns. We found that when a gentamicin-resistant gene was present in resistant enterococci from animals, that gene was also present in enterococci isolated from food products of the same animal species. Although these data indicate much diversity among gentamicin-resistant enterococci, the data also suggest similarities in gentamicin resistance among enterococci isolated from humans, retail food, and farm animals from geographically diverse areas and provide evidence of the spread of gentamicin-resistant enterococci from animals to humans through the food supply.

Animal Diseases↗
PubMed2003

Malignant astrocytoma arising 10 years after combined treatment of craniopharyngioma.

Craniopharyngioma is the third most common intracranial tumor in childhood. Following surgery, virtually all patients present with hypopituitarism and are at considerable risk of tumor recurrence. Secondary tumors, however, are rare, occurring usually 10 years after diagnosis and associated with poor prognosis. We report on a 5 year-old boy in whom craniopharyngioma was diagnosed due to unilateral visual loss. After surgery he underwent conventional radiation therapy with a total tumor dose of 55 Gy, and had hormonal support with DDAVP, thyroxine, and a variable dose of hydrocortisone. Growth velocity declined slowly in the first 4 years, but improved later on again without GH therapy despite abnormal provocative tests. At the age of 15 years he developed peripheral facial nerve palsy due to a malignant astrocytoma (WHO grade III/IV). Repeated conventional radiation therapy with an additional stereotactic boost and chemotherapy could not prevent the fatal outcome. This observation may temper the use of radiosurgery in benign intracranial tumors.

Astrocytoma↗
PubMed2003

Presumed Pseudomonas folliculitis outbreak in children following an outdoor games event.

In early summer 2001, an outbreak of atypical rash occurred among children from 24 junior schools who attended an outdoor games event. The event comprised a series of five water games including a water slide, and within 24 hours of attending the event 151/593 (26%) children developed a papulopustular rash. The rash had a characteristic distribution, predominantly over the lower trunk and buttocks, with some involvement of the arms and legs. Pseudomonas aeruginosa was isolated from a water butt used to draw water for the games, and from the tank of a fire engine that supplied the water. Similar outbreaks, due to Pseudomonas folliculitis, have been previously described and in immunocompromised people this can be associated with serious illness. We recommend that superchlorinated water be used for water play events and that care be taken to avoid abrasive surfaces.

Child↗
PubMed2003

Achieving optimum filtration performance.

Medical device and equipment manufacturers are faced with a plethora of choices in filter media. All filtration companies have specialists who are experienced in the correct selection of filter media and filter configuration to achieve the optimum filtration performance and results. Device and equipment manufacturers can find a true consultant who will be able to recommend the best material and configuration to do the job.

Cellulose↗
PubMed2002

Options for change.

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Cost-Benefit Analysis↗
PubMed2002

Outcomes of patients with chronic renal insufficiency in the bypass angioplasty revascularization investigation.

BACKGROUND: Although severe chronic kidney disease (CKD) is an independent predictor of mortality among patients with coronary artery disease, the impact of mild CKD on morbidity and mortality has not been fully defined. METHODS AND RESULTS: Morbidity and mortality for the 3608 patients with multivessel coronary artery disease enrolled in the Bypass Angioplasty Revascularization Investigation randomized trial and registry were compared on the basis of the presence and absence of CKD, defined as a preprocedure serum creatinine level of >1.5 mg/dL. Seventy-six patients had CKD. Patients with renal insufficiency were older and more likely to have a history of diabetes, hypertension, and other comorbidities. Among patients undergoing PTCA, patients with CKD had a greater frequency of in-hospital death and cardiogenic shock (P<0.05 and 0.01, respectively). There was a trend toward a larger proportion of patients with CKD experiencing angina at 5 years (P=0.079). Patients with CKD had more cardiac admissions (P=0.003 and <0.0001 for patients undergoing PTCA and CABG, respectively) and a shorter time to subsequent CABG after initial revascularization than patients without CKD (P=0.01). CKD was associated with a higher risk of death at 7 years, both of all causes (relative risk 2.2, P<0.001) and of cardiac causes (relative risk 2.8, P<0.001). CONCLUSIONS: CKD is associated with an increased risk of recurrent hospitalization, subsequent CABG, and mortality. This increased risk of death is independent of and additive to the risk associated with diabetes.

Angina Pectoris↗
PubMed2002

Light cure units.

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Composite Resins↗
PubMed2002

Sibling pairs with affective disorders: resemblance of demographic and clinical features.

BACKGROUND: As part of a collaborative linkage study, the authors obtained clinical and demographic data on 160 families in which more than one sibling was affected with a bipolar illness. The aim of the study was to identify clinical characteristics that had a high degree of familiality. METHOD: Data on age at onset, gender, frequency of illness-episodes and proportion of manic to depressive episodes were examined to determine intra-pair correlations in affected sibling pairs. Dimension scales were developed measuring frequency and severity of lifetime mania, depression, psychosis and mood-incongruence of psychotic symptoms; degree of familial aggregation for scores on these dimensions was calculated. RESULTS: Sibling pairs correlated significantly for age at onset (p = 0.293, P < 0 001); dimension scores for psychosis (p = 0.332, P < 0.001); and proportion of manic to depressive episodes (p = 0.184, P = 0.002). These findings remained significant when correcting for multiple testing. Of the other test variables; mania (p = 0.171, P = 0.019); incongruence dimensions (p = 0.242, P = 0.042); .frequency of manic episodes (p = 0.152, P = 0.033); and frequency of depressive episodes (p = 0.155, P = 0.028) were associated with modest correlations but these were not significant after correction. Degree of familial aggregation was not significant for sex (kappa = 0.084) or dimension scores for depression (p = 0.078, P = 0.300). CONCLUSIONS: Significant but modest familial resemblance has been shown for some specific features of bipolar illness, particularly age at onset and degree of psychosis. Further research may establish the extent to which these findings are mediated by genetic and/or environmental factors.

Bipolar Disorder↗
PubMed2002

Dose-response relationships for foot and mouth disease in cattle and sheep.

The relationships between the inhaled dose of foot and mouth disease virus and the outcomes of infection and disease were examined by fitting dose-response models to experimental data. The parameters for both the exponential and beta-poisson models were estimated using maximum likelihood and Bayesian methods. The median probability of infection given a single inhaled TCID50 was estimated to be 0.031 with 95% Bayesian credibility intervals (CI) of 0.018-0.052 for cattle, and 0.045 (CI = 0.024-0.080) for sheep. These estimates were used to construct dose-response curves and uncertainty distributions for use in quantitative risk assessments.

Animals↗