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Biomedical subjects

D B Smith

Publications and source records attributed to D B Smith.

At least 19 recordsLinked to original sources
PubMed2005

Methotrexate dosage reduction in patients with rheumatoid arthritis beginning therapy with infliximab: the Infliximab Rheumatoid Arthritis Methotrexate Tapering (iRAMT) trial.

OBJECTIVE: Infliximab plus methotrexate (MTX) is approved for the treatment of rheumatoid arthritis (RA). Based on the benefit/risk profile of this combination therapy, lower doses of MTX would be preferable when infliximab efficacy can be maintained. We evaluated the ability of patients receiving infliximab plus MTX to achieve and maintain a clinical response while the dose of MTX was tapered. METHODS: Infliximab infusions were administered at a minimum dosage of 3 mg/kg at 8-week intervals (following three loading doses at weeks 0, 2, and 6) to patients who had an inadequate response to MTX. MTX tapering was initiated at week 22 or later when at least a 40% improvement in the combined tender and swollen joint count was achieved; dosages were reduced by 5 mg every 8 weeks to a protocol-specified minimum dosage of 5 mg per week. If the required dosage of MTX after a flare was greater than the baseline dosage, the patient was considered a treatment failure. RESULTS: Of the 210 patients enrolled, 159 (76%) achieved a 40% or better improvement in the combined tender and swollen joint count and had their MTX doses tapered. In these 159 responders, the median (mean) dose of MTX was reduced from 15 (16.5) mg per week at baseline to 5 (7.1) mg per week at week 54. From the time of initial response, 79% of these patients had a zero- or a one-vial increase in infliximab, corresponding to an approximate dose increase of 1 mg/kg, through week 54. CONCLUSION: Approximately 75% of the patients participating in this trial achieved at least a 40% reduction in the combined swollen and tender joint count (correlating with an American College of Rheumatology 20% [ACR20] response in 83% of patients) while reducing the mean MTX dose by 57%.

Adolescent↗
PubMed2003

Oral antibiotics with early hospital discharge compared with in-patient intravenous antibiotics for low-risk febrile neutropenia in patients with cancer: a prospective randomised controlled single centre study.

Neutropenic sepsis remains a potentially life-threatening complication of anticancer chemotherapy. However, it is possible to identify patients who are at low risk for serious complications and for whom less-intensive, more-convenient treatment may be appropriate. The aim of this study was to assess the efficacy and safety of oral antibiotics in conjunction with early hospital discharge in comparison with standard in-patient intravenous antibiotics in patients with low-risk neutropenic fever. In all, 126 episodes of low-risk neutropenic fever occurred in 102 patients. Patients were randomised to receive either: an oral regimen of ciprofloxacin (750 mg 12 hourly) plus amoxicillin-clavulanate (675 mg 8 hourly) for a total of 5 days, or a standard intravenous regimen of gentamicin and tazocin (piperacillin/tazobactam) until hospital discharge. Patients randomised to oral antibiotics were eligible for discharge following 24 h of hospitalisation, if clinically stable and symptomatically improved. The efficacy of the two arms was similar: initial treatment was successful without antibiotic modification in 90% of episodes in the intravenous arm and 84.8% of episodes in the oral arm, P=0.55, absolute difference between the groups 5.2%; 95% confidence interval (CI) for the difference -7 to 17.3%. Only one episode in the oral arm was associated with significant clinical deterioration: this occurred within the initial in-patient assessment period. The median in-patient stay was 4 days in the intravenous arm (range 2-8) and 2 days in the oral arm (range 1-16 days), P&<0.0005. The reduction in hospital stay led to significant cost-savings in the oral arm. In conclusion, this study suggests that oral antibiotics in conjunction with early hospital discharge for patients who remain stable after a 24 h period of in-patient monitoring offers a feasible and cost-effective alternative to conventional management of low-risk neutropenic fever.

Administration, Oral↗
PubMed2001

Synergism between the potato glycoalkaloids alpha-chaconine and alpha-solanine in inhibition of snail feeding.

Snails (Helix aspersa L.) were fed filter paper treated with the potato glycoalkaloids, alpha-solanine and alpha-chaconine, singly or together. In pure form, both glycoalkaloids deterred feeding, with chaconine being the more active compound. In combination, authentic solanine and chaconine interacted synergistically in their inhibition of feeding. The antifeedant activities of methanolic extracts of tuber peel of the potato varieties Majestic and Sharpe's Express presented via filter paper discs did not differ significantly from those of authentic glycoalkaloid solutions of comparable concentration and ratio. In contrast, feeding inhibition by diluted tuber peel extracts of the variety Homeguard was greater than that elicited by comparable authentic glycoalkaloid solutions suggesting additional inhibitory compound(s) in the peel of this variety. Comparison of data from peel extracts of all three potato varieties and authentic glycoalkaloids indicated that the level of feeding inhibition by the extracts was, at least in part, a consequence of a synergism between solanine and chaconine.

Animals↗
PubMed2001

Investigating the influence of social desirability on personality factor structure.

This study provides a comprehensive investigation into whether social desirability alters the factor structure of personality measures. The study brought together 4 large data sets wherein different organizational samples responded to different personality measures. This facilitated conducting 4 separate yet parallel investigations. Within each data set, individuals identified through a social desirability scale as responding in an honest manner were grouped together, and individuals identified as responding in a highly socially desirable manner were grouped together. Using various analyses, the fit of higher order factor structure models was compared across the 2 groups. Results were the same for each data set. Social desirability had little influence on the higher order factor structures that characterized the relationships among the scales of the personality measures.

Adult↗
PubMed2001

Is everyone in agreement? An exploration of within-group agreement in employee perceptions of the work environment.

Multilevel researchers often gather individual-level data to measure group-level constructs. Within-group agreement is a key consideration in the measurement of such constructs, yet antecedents of within-group agreement have been little studied. The authors found that group member social interaction and work interdependence were significantly positively related to within-group agreement regarding perceptions of the work environment. Demographic heterogeneity was not significantly related to within-group agreement. Survey wording showed a complex relationship to agreement. Both evaluative items and socially undesirable items generated high within-group agreement. The use of a group rather than individual referent increased within-group agreement in response to descriptive items but decreased within-group agreement in response to evaluative items. Items with a group referent showed greater between-group variability than items with an individual referent.

Cooperative Behavior↗
PubMed2001

Personnel selection and the five-factor model: reexamining the effects of appplicant's frame of reference.

Recently, 2 separate yet related criticisms have been levied against the adequacy of the five-factor model (or Big Five) as a descriptive taxonomy of job applicant personality: frame of reference effects (M. J. Schmit & A. M. Ryan, 1993) and socially desirable responding (A. F. Snell & M. A. McDaniel, 1998). Of interest, although both criticisms suggest that the five-factor model is inadequate, the frame of reference effects criticism suggests that the factor structure should be more complex, whereas socially desirable responding suggests that it should be less complex in job applicant contexts. The current research reports the results of a new study demonstrating the adequacy of the five-factor model as a descriptor of job applicant, job incumbent, and student personality. Implications for personality assessment and concurrent validation designs using personality measures are also discussed.

Adult↗
PubMed2001

Dynamic in vitro quantification of bioprosthetic heart valve leaflet motion using structured light projection.

Quantification of heart valve leaflet deformation during the cardiac cycle is essential in understanding normal and pathological valvular function, as well as in the design of replacement heart valves. Due to the technical complexities involved, little work to date has been performed on dynamic valve leaflet motion. We have developed a novel experimental method utilizing a noncontacting structured laser-light projection technique to investigate dynamic leaflet motion. Using a simulated circulatory loop, a matrix of 150-200 laser light points were projected over the entire leaflet surface. To obtain unobstructed views of the leaflet surface, a stereo system of high-resolution boroscopes was used to track the light points at discrete temporal points during the cardiac cycle. The leaflet surface at each temporal point was reconstructed in three dimensions, and fit using our biquintic hermite finite element approach (Smith et al., Ann. Biomed. Eng. 26:598-611, 2001). To demonstrate our approach, we utilized a bovine pericardial bioprosthetic heart valve, which revealed regions of complex flexural deformation and substantially different shapes during the opening and closing phases. In conclusion, the current method has high spatial and temporal resolution and can reconstruct the entire surface of the cusp simultaneously. Because it is completely noncontacting, this approach is applicable to studies of fatigue and bioreactor technology for tissue engineered heart valves.

Algorithms↗
PubMed2001

Droplet size and spray volume effects on insecticide deposit and mortality of heliothine (Lepidoptera: Noctuidae) larvae in cotton.

Effects of droplet size and volumetric application rate of tractor-applied lambda cyhalothrin (Karate Z 2.08 SC) on larval tobacco budworm, Heliothis virescens (F.), mortality and insecticide deposition on and within the canopy of mature cotton were explored by use of a laboratory bioassay incorporating field-sprayed cotton and a field trial incorporating natural insect infestations. Insecticide was applied in all combinations of three distinct droplet sizes and three volumetric application rates. Mortality of third-instar tobacco budworm occurring in leaf-disk bioassays was highly correlated with insecticide deposits (microg/leaf disk) at upper- and midcanopy levels. At the upper canopy level, mortality was negatively correlated with volumetric application rate and was not significantly correlated with droplet size. Deposit was negatively correlated with volumetric application rate at the lower plant level and larval mortality decreased with increasing droplet size. Results from this study do not support the recommendations of high volumetric application rates; and although droplet size was less influential than volumetric application rate in deposit and insect mortality, the data indicate a significant trend toward increased midcanopy larval mortality with smaller droplets.

Animals↗
PubMed2001

Mechanomyography, electromyography, heart rate, and ratings of perceived exertion during incremental cycle ergometry.

BACKGROUND: The purpose of this investigation was to examine the relationships of mchanomyography (MMG), electromyography (EMG), heart rate (HR), and ratings of perceived exertion (RPE) versus power output during incremental cycle ergometry. METHODS: Nine adult males [mean (+/-SD) age 23 (+/-3) years] volunteered to perform an incremental test to exhaustion on a cycle ergometer. The MMG, EMG, HR, and RPE values were recorded at the end of each power output. RESULTS: The normalized (expressed as a percentage of maximal values) relationships for MMG, HR, and RPE versus power output were linear, while the EMG versus power output relationship was quadratic. Furthermore, there were no significant (p > 0.10) differences between slope coefficients for the relationships among MMG, HR, and RPE versus power output. CONCLUSIONS: The results of this investigation indicated that there were close associations among the mechanical (MMG), cardiac (HR), and perception of effort (RPE) aspects of cycle ergometry. In addition, there was a dissociation between the linear MMG pattern and quadratic EMG pattern with increasing power outputs.

Adult↗
PubMed2001

The effect of concentric isokinetic strength training of the quadriceps femoris on electromyography and muscle strength in the trained and untrained limb.

The purpose of the present investigation was to examine the effects of unilateral concentric isokinetic leg extension training on peak torque (PT) and electromyographic (EMG) responses in the trained and untrained limbs. Twenty adult men were randomly assigned to a training (TRN, n = 11) or control (CTL, n = 9) group. The TRN group performed 6 sets of 10 leg extensions 3 days per week for 12 weeks at a velocity of 90 degrees.s(-1). All subjects were tested every 4 weeks for PT and EMG responses of both legs at a velocity of 90 degrees.s(-1). The 3-way mixed factorial analysis of variance (ANOVA) indicated a significant (p < 0.05) increase in PT over the 12 weeks in both the trained and untrained limb for the TRN group but no significant change in PT in either limb for the CTL group. The results of the 3-way ANOVA for the EMG data indicated no significant change in EMG amplitude in the trained or untrained limb for the TRN or CTL group. The increase in PT in the absence of a change in EMG may result from hypertrophic factors and/or changes in the other muscles or muscle groups involved in leg extension.

Adaptation, Physiological↗
PubMed2000

The effect of leg extension training on the mean power frequency of the mechanomyographic signal.

The purpose of the present investigation was to examine the effect of concentric isokinetic leg extension training on the mean power frequency (MPF) of the mechanomyographic (MMG) signal. Twenty-one men were assigned into a training (TRN; n = 12) or control (CTL; n = 9) group. The TRN group performed six sets of leg extensions 3 days per week for 12 weeks at a velocity of 90 degrees /s. All subjects were tested every 4 weeks for peak torque (PT), while MMG was recorded from the vastus lateralis. PT increased, but there was no significant (P > 0.05) change in the MMG MPF over the 12-week training period. These results indicate that MMG MPF, measured from the vastus lateralis, was not sensitive to training-induced increases in leg-extension strength, possibly due to competing influences of hypertrophy on the MMG signal and/or training-induced adaptations in muscles other than the vastus lateralis.

Electromyography↗
PubMed2000

Low-dose continuous-infusion ceftazidime monotherapy in low-risk febrile neutropenic patients.

One hundred and thirty-five cancer patients admitted with low-risk neutropenic fever received a low-dose schedule of ceftazidime as infusional monotherapy over a total of 180 episodes. Ceftazidime was administered as a 1-g bolus followed by a continuous infusion of 2 g per day. In this patient population the ceftazidime was both practical and well tolerated. Sixty-eight percent of patients responded with clinical improvement and complete resolution of fever within 48 h. Overall, 95% of patients responded, although 18% subsequently required antibiotic modification for persistent fever. Only 5% of episodes were considered failures due to clinical deterioration, and over the study period there was only 1 fatality due to respiratory failure. The median duration of hospitalisation was only 4 days (2-20). In conclusion, monotherapy with low-dose infusional ceftazidime appears safe and highly effective in this low-risk population of neutropenic patients and may reduce antibiotic costs appreciably.

Adult↗
PubMed2000

Diversity of hepatitis G virus within a single infected individual.

The extent of population diversity among GB virus C (GBV-C)/hepatitis G virus (HGV) within a persistently infected individual (Iw) was investigated by sequence analysis of multiple clones generated from polymerase chain reaction (PCR)-amplified products of cDNA analogous to fragments of 5' non-coding region (5'NC), envelope region 1/2 (E1/E2) and non-structural region 3 (NS3) of viral genome. Although nucleotide substitutions were more common in coding regions than in the 5'NC region, there was no region corresponding to the hypervariable region of hepatitis C virus in the E1/E2 region. Transition substitution exceeded transversion by 7 to 12-fold, and 79.4% of substitutions were synonymous. This bias against substitutions producing amino acid replacements and the use of Pfu DNA polymerase with an error rate 10 times lower than the observed frequency of substitution, suggests that most substitutions were not artefactual. This data suggests that individual genomes of HGV within an infected individual may differ from each other at 0.23-0.84% nucleotide position and at 0.42-0.61% amino acid position.

Base Sequence↗
PubMed2000

A self-directed home biofeedback system for women with symptoms of stress, urge, and mixed incontinence.

PURPOSE: To evaluate a self-directed home biofeedback treatment system in a group of community dwelling, otherwise healthy women with symptoms of stress, urge, and mixed urinary incontinence (UI). SETTING AND SUBJECTS: Fifty-five women, aged 25 to 81 years, participated in the study. METHODS: Initial evaluation included a self-reported continence assessment, a 24-hour bladder and fluid habits diary, severity indices for stress and urge UI, and assessment of pelvic floor strength using a pneumatic biofeedback device. Subjects completed a 16-week self-directed program. Assessment and severity index data were self-reported using a continence assessment form, a 24-hour bladder habit and fluid form, and stress and urge incontinence severity indices. Strength level of the trainer, number of digital bands lit on the screen during contraction, number of sessions, and program (starter, intermediate, advanced, or maintenance) were recorded on data sheets. INSTRUMENTS: The treatment system includes an 8-minute educational and motivational video; a journal for education, instructions, and daily documentation forms; and a home biofeedback trainer with pneumatic vaginal sensors that displays the strength of pelvic muscle contraction. RESULTS: Forty-four women completed the 16-week program. At the end of treatment, 19 (43%) were dry and 16 (36%) reported 50% or more improvement in number of leaks per day, number of voids per day, or both. Women with stress leakage experienced a significant reduction in the number of incontinent episodes per day and the mean severity index of incontinence (P < .001). Participants with urge UI experienced a significant reduction in the mean number of voids per day and mean severity index for UI (P < .001). Younger subjects were more likely to improve when compared with older participants, but no significant differences were found when comparing women who take estrogen with those who do not take estrogen or when comparing those with a history of bladder surgery with those who had no previous surgery. CONCLUSIONS: These data suggest that self-selected healthy women with symptoms of urge, stress, and mixed incontinence can improve their symptoms and lower their severity index with a minimal intervention, comprehensive, self-directed home biofeedback continence system.

Adult↗
PubMed2000

Phylogenetic analysis of GBV-C/hepatitis G virus.

Comparison of 33 epidemiologically distinct GBV-C/hepatitis G virus complete genome sequences suggests the existence of four major phylogenetic groupings that are equally divergent from the chimpanzee isolate GBV-C(tro) and have distinct geographical distributions. These four groupings are not consistently reproduced by analysis of the virus 5'-noncoding region (5'-NCR), or of individual genes or subgenomic fragments with the exception of the E2 gene as a whole or of 200-600 nucleotide fragments from its 3' half. This region is upstream of a proposed anti-sense reading frame and contains conserved potential RNA secondary structures that may be capable of directing the internal initiation of translation. Phylogenetic analysis of this region from certain South African isolates is consistent with previous analysis of the 5'-NCR suggesting that these belong to a fifth group. The geographical distribution of virus variants is consistent with a long evolutionary history that may parallel that of pre-historic human migrations, implying that the long-term evolution of this RNA virus is extremely slow.

5' Untranslated Regions↗