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Bruce A Craig

Publications and source records attributed to Bruce A Craig.

15 recordsLinked to original sources
PubMed2026

Characterizing Submental Neuromuscular Activity of Swallowing Rehabilitation: An Electromyographic Evaluation of Rehabilitative Maneuvers in Healthy Adults.

PURPOSE: The effortful swallow (ES), the Mendelsohn maneuver (MM), and isometric tongue presses (TPs) are widely used swallowing maneuvers/exercises to improve elements of swallowing, such as muscle strength and biomechanics. However, the underlying neuromuscular mechanisms of these exercises remain unclear, potentially limiting our ability to specify treatment targets and improve treatment efficacy. This study aimed to compare submental neuromuscular activation patterns during the ES, MM, TPs, and typical swallows in healthy young and older adults. METHOD: As part of a larger randomized crossover validation study, 60 healthy adults (30 young and 30 older) completed typical swallows and three maneuvers using a wearable submental surface electromyographic (sEMG) system (i-Phagia). Outcome variables included (a) normalized mean sEMG amplitude and (b) time to peak sEMG amplitude. Linear mixed models were used to examine effects of task, age, and sex on both outcomes. RESULTS: Normalized mean amplitude was significantly different across tasks. Post hoc pairwise comparisons confirmed that all three maneuvers produced higher normalized mean sEMG amplitude than typical swallows, with the ES eliciting the highest amplitude across age groups. Time to peak amplitude differed significantly across tasks, with typical swallows requiring the shortest time to reach peak amplitude, followed by the ES, MM, and TP. CONCLUSIONS: The ES required the highest neuromuscular effort with the shortest time to reach peak amplitude, suggesting its potential for targeting submental muscle power. Typical swallows required the least neuromuscular effort with the shortest time to reach peak amplitude, suggesting their potential for training submental muscle speed. The MM and TP may also improve submental muscle strength; however, given their temporal requirements (longer durations), they may be more beneficial for targeting coordination and endurance, though more research in this area is warranted. These findings underscore the importance of task-specific neuromuscular profiling to inform mechanism-based swallowing rehabilitation. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.32948549.

Humans↗
PubMed2006

Incorporating time-dependent covariates in survival analysis using the LVAR method.

In survival analysis, use of the Cox proportional hazards model requires knowledge of all covariates under consideration at every failure time. Since failure times rarely coincide with observation times, time-dependent covariates (covariates that vary over time) need to be inferred from the observed values. In this paper, we introduce the last value auto-regressed (LVAR) estimation method and compare it to several other established estimation approaches via a simulation study. The comparison shows that under several time-dependent covariate processes this method results in a smaller mean square error when considering the time-dependent covariate effect.

Computer Simulation↗
PubMed2006

Physical activity status, but not age, influences inflammatory biomarkers and toll-like receptor 4.

BACKGROUND: Chronic inflammation has been implicated in the development of cardiovascular disease, diabetes mellitus, cachexia, and osteoporosis. Regular physical activity has been purported to possess "anti-inflammatory" properties which may limit chronic inflammation. Recently, we hypothesized that toll-like receptor 4 (TLR4) may play a role in activity-induced modulation of inflammation. Therefore, the purpose of this study was to determine the association between age, physical activity status, biomarkers of inflammation, and TLR4. METHODS: Male and female participants (n = 84) were recruited to fill one of the following groups: young (18-30 years), active; young, inactive; old (60-80 years), active; or old, inactive. To assess physical activity status, participants completed a Paffenbarger Physical Activity Questionnaire and a modified Balke submaximal treadmill test. After grouping and screening, participants were given a standard mixed diet to consume 24 hours prior to arriving at the laboratory. Participants were instructed to consume all food by 10 pm the night prior to blood sampling (8-hour fast). Following 30 minutes of seated rest in a quiet room, venous blood samples were collected. Lipopolysaccharide-stimulated inflammatory cytokine production and plasma high-sensitivity C-reactive protein (hsCRP) were determined by enzyme-linked immunosorbent assay, and TLR4 expression was determined by flow cytometry. RESULTS: Lipopolysaccharide-stimulated interleukin-6, interleukin-1beta, and tumor necrosis factor-alpha production, TLR4 expression, and hsCRP were significantly lower in active compared to inactive participants (p <.05). Also, older participants had significantly higher hsCRP than young participants had (p <.05). CONCLUSIONS: The findings of the present study support previous reports which infer that acute exercise or a physically active lifestyle may possess anti-inflammatory properties. Also this study, along with previous work from our laboratory, suggests that TLR4 may play a role in regulating the link between inflammatory cytokine production and a physically active lifestyle.

Adult↗
PubMed2006

Cyclooxygenase inhibitors in urinary bladder cancer: in vitro and in vivo effects.

More than 14,000 people die from invasive transitional cell carcinoma (TCC) of the urinary bladder yearly in the United States. Cyclooxygenase (COX)-inhibiting drugs are emerging as potential antitumor agents in TCC. The optimal in vitro or in vivo systems to investigate COX inhibitor antitumor effects have not been defined. The purpose of this study was to determine COX-1 and COX-2 expression and antitumor effects of COX inhibitors in human TCC cell lines (HT1376, RT4, and UMUC3 cells) and xenografts derived from those cell lines. COX-2 expression (Western blot, immunocytochemistry) was high in HT1376, modest in RT4, and absent in UMUC3 cells in vitro. Similarly, COX-2 expression was noted in RT4 but not UMUC3 xenografts. COX-2 expression in HT1376 xenografts was slightly lower than that observed in vitro. None of four COX inhibitors evaluated (celecoxib, piroxicam, valeryl salicylate, and NS398) reduced TCC growth in standard in vitro proliferation assays at concentrations that could be safely achieved in vivo (< or =5 micromol/L). Higher celecoxib concentrations (> or =50 micromol/L) inhibited proliferation and induced apoptosis in all three cell lines. Celecoxib or piroxicam treatment in athymic mice significantly delayed progression of HT1376 xenografts, which express COX-2, but not UMUC3 xenografts that lack COX-2 expression. In conclusion, standard in vitro assays were not useful in predicting COX inhibitor antitumor effects observed in vivo. Athymic mice bearing TCC xenografts provide a useful in vivo system for COX inhibitor studies. Results of this study provide justification for further evaluation of COX inhibitors as antitumor agents against TCC.

Animals↗
PubMed2005

Statistical properties and inference of the antimicrobial MIC test.

A common method for measuring the drug-specific minimum inhibitory concentration (MIC) of an antibacterial agent is via a two-fold broth dilution test known as the MIC test. Because this procedure implicitly rounds data upward, inference based on unadjusted measurements is biased and overestimates bacterial resistance to a drug. We detail this test procedure and its associated bias, which, in many cases, has an expected value of approximately 0.5 on the log(2) scale. In addition, new bias-corrected estimates of resistance are proposed. A numeric example is used to illustrate the extent to which the traditional resistance estimate can overestimate the true proportion of resistant strains, a phenomenon which is remedied by using the proposed estimates.

Bias↗
PubMed2005

A model selection-based interval-mapping method for autopolyploids.

While extensive progress has been made in quantitative trait locus (QTL) mapping for diploid species, similar progress in QTL mapping for polyploids has been limited due to the complex genetic architecture of polyploids. To date, QTL mapping in polyploids has focused mainly on tetraploids with dominant and/or codominant markers. Here, we extend this view to include any even ploidy level under a dominant marker system. Our approach first selects the most likely chromosomal marker configurations using a Bayesian selection criterion and then fits an interval-mapping model to each candidate. Profiles of the likelihood-ratio test statistic and the maximum-likelihood estimates (MLEs) of parameters including QTL effects are obtained via the EM algorithm. Putative QTL are then detected using a resampling-based significance threshold, and the corresponding parental configuration is identified to be the underlying parental configuration from which the data are observed. Although presented via pseudo-doubled backcross experiments, this approach can be readily extended to other breeding systems. Our method is applied to single-dose restriction fragment autotetraploid alfalfa data, and the performance is investigated through simulation studies.

Algorithms↗
PubMed2005

Influence of exercise training and age on CD14+ cell-surface expression of toll-like receptor 2 and 4.

The influence of an exercise training program and age on inflammatory cytokine production and CD14+cell-surface expression of toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) was examined in 60 younger and older subjects. Subjects were assigned to: young physically active (YPA, n = 15; 25.2 +/- 5.0 years), young physically inactive (YPI, n = 14; 24.9 +/- 4.7 years), older physically active (OPA, n = 14; 71.2 +/- 4.4 years) or older physically inactive (OPI, n = 17; 71.0 +/- 4.3 years) groups. YPI and OPI completed 12 weeks (3 days/week) of endurance (20 min) and resistance exercise (eight exercises, two sets). YPA and OPA groups were instructed to continue their normal activity for 12 weeks. Blood was collected at rest, before and after the 12-week training and control period. A whole blood method was used to determine lipopolysaccharide-(LPS) and peptidoglycan-(PGN) stimulated IL-6, IL-1beta, and TNF-alpha production with supernatants analyzed using ELISA. CD14+ cell-surface expression of TLR2 and TLR4 were measured using flow cytometry. Training increased estimated VO(2max) by 10.4% and increased strength by an average of 38.1%. YPI and OPI had a post-training reduction in LPS-stimulated IL-6 production (P < .01), but LPS-stimulated IL-1beta and TNF-alpha and PGN-stimulated cytokines were not changed. CD14+ cell TLR4 was significantly reduced (P < .05) in YPI and OPI groups after training, but TLR2 was not significantly changed. An exercise training program reduced LPS-stimulated IL-6, concomitant with lower TLR4. These results provide further support for a training- or physical activity-induced lowering of TLR4 and inflammation.

Adolescent↗
PubMed2005

The effect of interlaboratory variability on antimicrobial susceptibility determination.

In the minimum inhibitory concentration (MIC) test literature, discussion concerning the effect of laboratory-to-laboratory variation is lacking. We present 2 sets of drug dilution test quality control data that illustrate considerable laboratory differences in measured MIC. In both isolates (Escherichia coli, ATCC 25922; Staphylococcus aureus, ATCC 29213) the laboratory-to-laboratory variability accounts for approximately half of the total variability. We illustrate the impact of this variability on the probability of correctly classifying the susceptibility level of an isolate and on the estimation of resistance prevalence. For example, we show that laboratory differences in the probability of correctly classifying the isolate (specifically near the lower breakpoint) can vary up to 80%.

Anti-Bacterial Agents↗
PubMed2003

Gene expression profiling of Caco-2 BBe cells suggests a role for specific signaling pathways during intestinal differentiation.

We examined the pattern of gene expression resulting from spontaneous differentiation of Caco-2 BBe cells to gain insight into the molecular changes necessary for enterocyte differentiation. RNA was prepared from cells harvested at three cell stages: proliferating (50% confluent, 2 days in culture), postproliferative nondifferentiated (8 days), and differentiated (15 days). Gene expression profiles were determined using Affymetrix Human Genome U95A GeneChips. Differentially expressed genes were identified following statistical analysis (i.e., ANOVA, bootstrapping adjustments to P values, false detection rate criterion). We identified 1,150 unique genes as differentially expressed; expression of 48.6% fell and 46% increased from 2 to 15 days, while 5.4% had expression that either peaked or dipped at 8 days. Genes expressed during differentiation included several small-intestine-specific genes involved in nutrient transport/metabolism, e.g., DCT1, hephaestin, folate receptor 1, sucrase-isomaltase, and apolipoproteins CI, CIII, B100, H, and M, indicating that this colonic adenocarcinoma cell line has a hybrid colonocyte/enterocyte phenotype. Patterns of gene expression based upon functional classification suggest a role for cell-cell/cell-matrix interactions, suppression of Wnt signaling, and activation of TGFbeta and phosphatidylinositol 3-kinase pathways during enterocyte differentiation.

Caco-2 Cells↗
PubMed2003

Effects of the cyclooxygenase inhibitor, piroxicam, in combination with chemotherapy on tumor response, apoptosis, and angiogenesis in a canine model of human invasive urinary bladder cancer.

The objectives of this study were: (a) to determine the antitumor activity and toxicity of a cyclooxygenase inhibitor (piroxicam) combined with cisplatin chemotherapy in dogs with naturally-occurring, invasive transitional cell carcinoma (TCC) of the urinary bladder; and (b) to determine the effects of this treatment on prostaglandin E(2) concentration, tumor cell proliferation and apoptosis, and angiogenesis. Pet dogs with naturally-occurring invasive TCC underwent complete tumor staging before and after 10 weeks of piroxicam/cisplatin treatment. Prostaglandin E(2) concentrations were determined by immunoassay in snap-frozen tumor tissues. Apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling assay), proliferation (proliferating cell nuclear antigen), and microvessel density were determined in formalin-fixed tissues. Urine basic fibroblast growth factor and vascular endothelial cell growth factor concentrations were determined by immunoassay. Partial remission (> or =50% reduction in tumor volume) was noted in 6 of 12 dogs treated with piroxicam/cisplatin. Renal toxicity was dose-limiting. Apoptotic index doubled with treatment in 11 of 12 dogs but was not associated with tumor response. Proliferative index decreased in five dogs, and tumor decreased in size in three of the five dogs. Change in urine basic fibroblast growth factor and vascular endothelial cell growth factor was associated with tumor response. microvessel density was not associated with tumor response. In conclusion, piroxicam/cisplatin had antitumor activity against canine TCC, a disease that closely mimics human invasive urinary bladder cancer. Strategies to prevent renal toxicity of this protocol are needed. Induction of tumor apoptosis and reduction in angiogenic factor concentrations were observed, but additional studies are needed to further define the mechanisms of the antitumor activity of piroxicam/cisplatin.

Animals↗
PubMed2002

Estimating disease prevalence in the absence of a gold standard.

When estimating disease prevalence, it is not uncommon to have data from conditionally dependent diagnostic tests. In such a situation, the estimation of prevalence is difficult if none of the tests is considered to be a gold standard. In this paper we develop a Bayesian approach to estimating disease prevalence based on the results of two diagnostic tests, allowing for the possibility that the tests are conditionally dependent, but not conditioning on any particular dependence structure. This involves the construction of four models with various forms of conditional dependence and uses Bayesian model averaging, enabled by reversible jump MCMC, to obtain an overall estimate of the prevalence. This methodology is demonstrated using a study on the prevalence of Strongyloides infection.

Animals↗
PubMed2002

Effects of the cyclooxygenase inhibitor, piroxicam, on tumor response, apoptosis, and angiogenesis in a canine model of human invasive urinary bladder cancer.

The mechanisms by which cyclooxygenase inhibitors exert antitumor effects are not completely defined but are postulated to involve antiangiogenic effects and induction of apoptosis. In this study, we determined the effects of the cox inhibitor, piroxicam, on tumor response, apoptotic index, proliferative index, cyclooxygenase-2 expression, prostaglandin E(2) concentration, tumor microvessel density, and urine basic fibroblast growth factor and vascular endothelial growth factor concentrations in pet dogs with naturally occurring invasive transitional cell carcinoma of the urinary bladder. Piroxicam caused reduction in tumor volume in 12 of 18 dogs, and this was strongly associated with induction of apoptosis (Fisher's exact test P < 0.015) and reduction in urine basic fibroblast growth factor concentration.

Animals↗
PubMed2002

Estimation of the transition matrix of a discrete-time Markov chain.

Discrete-time Markov chains have been successfully used to investigate treatment programs and health care protocols for chronic diseases. In these situations, the transition matrix, which describes the natural progression of the disease, is often estimated from a cohort observed at common intervals. Estimation of the matrix, however, is often complicated by the complex relationship among transition probabilities. This paper summarizes methods to obtain the maximum likelihood estimate of the transition matrix when the cycle length of the model coincides with the observation interval, the cycle length does not coincide with the observation interval, and when the observation intervals are unequal in length. In addition, the bootstrap is discussed as a method to assess the uncertainty of the maximum likelihood estimate and to construct confidence intervals for functions of the transition matrix such as expected survival.

Algorithms↗
PubMed2002

Modeling the impact of adjustable gastric banding on survival in patients with morbid obesity.

OBJECTIVE: Morbid obesity is associated with premature death. Adjustable gastric banding may lead to substantial weight loss in patients with morbid obesity. Little is known about the impact of weight loss on survival after adjustable gastric banding. We therefore developed a mathematical model to estimate life expectancy in patients with a body mass index (BMI) > or =40 kg/m(2) undergoing bariatric surgery. RESEARCH METHODS AND PROCEDURES: We developed a nonhomogeneous Markov chain consisting of five states: the absorbing state ("dead") and the four recurrent states BMI > or =40 kg/m(2), BMI 36 to 39 kg/m(2), BMI 32 to 35 kg/m(2), and BMI 25 to 31 kg/m(2). Scenarios of weight loss and age- and sex-dependent risk of death, as well as BMI-dependent excess mortality were extracted from life tables and published literature. All patients entered the model through the state of BMI > or =40 kg/m(2). RESULTS: In men aged either 18 or 65 years at the time of surgery, who moved from the state BMI > or =40 kg/m(2) to the next lower state of BMI 36 to 39 kg/m(2), life expectancy increased by 3 and 0.7 years, respectively. In women aged either 18 or 65 years at the time of surgery, who moved from the state BMI > or =40 kg/m(2) to the next lower state BMI 36 to 39 kg/m(2), life expectancy increased by 4.5 and 2.6 years, respectively. Weight loss to lower BMI strata resulted in further gains of life expectancy in both men and women. DISCUSSION: Within the limitations of the modeling study, adjustable gastric banding in patients with morbid obesity may substantially increase life expectancy.

Adolescent↗