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Dive into the research topics where David K. Williams is active.

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Featured researches published by David K. Williams.


American Journal of Psychiatry | 2013

Practice Based Versus Telemedicine Based Collaborative Care for Depression in Rural Federally Qualified Health Centers: A Pragmatic Randomized Comparative Effectiveness Trial

John C. Fortney; Jeffrey M. Pyne; Sip Mouden; Dinesh Mittal; Teresa J. Hudson; Gary W. Schroeder; David K. Williams; Carol A. Bynum; Rhonda Mattox; Kathryn Rost

OBJECTIVE Practice-based collaborative care is a complex evidence-based practice that is difficult to implement in smaller primary care practices that lack on-site mental health staff. Telemedicine-based collaborative care virtually co-locates and integrates mental health providers into primary care settings. The objective of this multisite randomized pragmatic comparative effectiveness trial was to compare the outcomes of patients assigned to practice-based and telemedicine-based collaborative care. METHOD From 2007 to 2009, patients at federally qualified health centers serving medically underserved populations were screened for depression, and 364 patients who screened positive were enrolled and followed for 18 months. Those assigned to practice-based collaborative care received evidence-based care from an on-site primary care provider and a nurse care manager. Those assigned to telemedicine-based collaborative care received evidence-based care from an on-site primary care provider and an off-site team: a nurse care manager and a pharmacist by telephone, and a psychologist and a psychiatrist via videoconferencing. The primary clinical outcome measures were treatment response, remission, and change in depression severity. RESULTS Significant group main effects were observed for both response (odds ratio=7.74, 95% CI=3.94-15.20) and remission (odds ratio=12.69, 95% CI=4.81-33.46), and a significant overall group-by-time interaction effect was observed for depression severity on the Hopkins Symptom Checklist, with greater reductions in severity over time for patients in the telemedicine-based group. Improvements in outcomes appeared to be attributable to higher fidelity to the collaborative care evidence base in the telemedicine-based group. CONCLUSIONS Contracting with an off-site telemedicine-based collaborative care team can yield better outcomes than implementing practice-based collaborative care with locally available staff.


Journal of Neurophysiology | 2010

Gamma band unit activity and population responses in the pedunculopontine nucleus.

Christen Simon; Nebojsa Kezunovic; Meijun Ye; James Hyde; Abdallah Hayar; David K. Williams; Edgar Garcia-Rill

The pedunculopontine nucleus (PPN) is involved in the activated states of waking and paradoxical sleep, forming part of the reticular activating system (RAS). The studies described tested the hypothesis that single unit and/or population responses of PPN neurons are capable of generating gamma band frequency activity. Whole cell patch clamp recordings (immersion chamber) and population responses (interface chamber) were conducted on 9- to 20-day-old rat brain stem slices. Regardless of cell type (I, II, or III) or type of response to the nonselective cholinergic receptor agonist carbachol (excitation, inhibition, biphasic), almost all PPN neurons fired at gamma band frequency, but no higher, when subjected to depolarizing steps (50 +/- 2 Hz, mean +/- SE). Nonaccommodating neurons fired at 18-100 Hz throughout depolarizing steps, while most accommodating neurons exhibited gamma band frequency of action potentials followed by gamma band membrane oscillations. These oscillations were blocked by the sodium channel blocker tetrodotoxin (TTX), suggesting that at least some are mediated by sodium currents. Population responses in the PPN showed that carbachol induced peaks of activation in the theta and gamma range, while glutamatergic receptor agonists induced overall increases in activity at theta and gamma frequencies, although in differing patterns. Gamma band activity appears to be a part of the intrinsic membrane properties of PPN neurons, and the population as a whole generates different patterns of gamma band activity under the influence of specific transmitters. Given sufficient excitation, the PPN may impart gamma band activation on its targets.


Pharmacotherapy | 2004

Influence of grapefruit juice on the systemic availability of itraconazole oral solution in healthy adult volunteers

Paul O. Gubbins; Scott A. McConnell; Bill J. Gurley; Timothy K. Fincher; Amy M. Franks; David K. Williams; Scott R. Penzak; Michael Saccente

Study Objective. To evaluate the effect of repeated ingestion of grapefruit juice on the systemic availability of itraconazole (ITZ) and hydroxy‐itraconazole (OHITZ) serum concentrations in subjects administered hydroxypropyl‐β‐cyclodextrin‐ITZ (HP‐β‐CD ITZ) oral solution.


Journal of neonatal-perinatal medicine | 2013

Does daily kangaroo care provide sustained pain and stress relief in preterm infants

Anita Mitchell; Charlotte Yates; David K. Williams; Jason Y. Chang; Richard W. Hall

OBJECTIVES 1. Determine whether stress in preterm infants, measured with salivary cortisol, decreases after five days of Kangaroo Care (KC) compared to five days of Standard Care (SC). 2. To determine whether kangaroo care provides sustainable pain relief beyond the period of skin-to-skin holding. STUDY DESIGN Preterm infants (n = 38) born at 27-30 weeks gestational age were randomized to either the KC or the SC group and received the allocated intervention starting on day of life (DOL) five and continuing for five days. Salivary cortisol was collected on DOL five and again on DOL ten. Differences were analyzed using repeated measures ANOVA and t tests. Pain during nasal suctioning over five days was assessed using the Premature Infant Pain Profile (PIPP). RESULT 1. Adequate saliva samples for salivary cortisol were collected for 13 KC infants and 11 SC infants. There was no main effect of group (p = 0.49), but there was a significant main effect of age (DOL five versus DOL ten), with salivary cortisol levels decreasing in both groups (p = 0.02). 2. Pain scores for both groups (n = 38) indicted mild to moderate pain during suctioning, with no significant difference in pain scores between groups. CONCLUSION 1. KC did not affect salivary cortisol levels in preterm neonates, but levels in both the KC and SC groups decreased over time from DOL five to ten. Salivary cortisol may vary with age of infant. 2. Infants experience pain during routine suctioning and may require pain management.


Clinical Neurophysiology | 2005

The P50 midlatency auditory evoked potential in patients with chronic low back pain (CLBP)

Alice V. Fann; Michael A. Preston; Patricia Bray; Noriaki Mamiya; David K. Williams; R.D. Skinner; Edgar Garcia-Rill

OBJECTIVE Patients with Chronic Low Back Pain (CLBP) show arousal, attentional and cognitive disturbances. The sleep state-dependent P50 midlatency auditory evoked potential was used to determine if patients with CLBP [with and without co-morbid depression (DEP)] show quantitative disturbances in the manifestation of the P50 potential. METHODS P50 potential latency, amplitude and habituation to repetitive stimuli at 250, 500 and 1000ms interstimulus intervals (ISIs) was recorded, along with the McGill Pain Questionnaire-Short Form (MPQ-SF). CLBP subjects (n=42) were compared with Controls (n=43), and with subjects with DEP only (n=6). Of the CLBP subjects, 20/42 had clinical depression (CLBP+DEP); 8/20 were taking anti-depressant medication (CLBP+DEP+med), the others were not (CLBP+DEP-med). RESULTS There were no differences (ANOVA) in age, sex or P50 potential latency, although there was a trend towards increased latencies in CLBP groups. P50 potential amplitude was lower in CLBP groups, but not in sub-groups, again indicating a trend. P50 potential habituation was decreased in the DEP only subjects at the 250m ISI, and decreased in CLBP+DEP-med subjects at the 500ms ISI. This difference was not present in CLBP+DEP+med subjects. The MPQ-SF revealed that patients with CLBP and CLBP+DEP-med showed lower pain scores than CLBP+DEP+med patients. CONCLUSIONS There is decreased habituation of the P50 potential habituation in unmedicated patients with CLBP+DEP compared to Controls. SIGNIFICANCE Patients with CLBP+DEP-med may be less able to disregard incoming sensory information, including painful sensations, but anti-depressant medications help correct this deficit. However, their perception of pain may be increased by medication.


Epilepsy Research | 2015

Pilocarpine-induced status epilepticus in mice: A comparison of spectral analysis of electroencephalogram and behavioral grading using the Racine scale

Kevin D. Phelan; U.T. Shwe; David K. Williams; L. John Greenfield; Fang Zheng

Pilocarpine-induced status epilepticus (SE) is a widely used seizure model in mice, and the Racine scale has been used to index seizure intensity. The goal of this study was to analyze electroencephalogram (EEG) quantitatively using fast Fourier transformation (FFT) and statistically evaluate the correlation of electrographic seizures with convulsive behaviors. Simultaneous EEG and video recordings in male mice in a mixed genetic background were conducted and pilocarpine was administered intraperitoneally to induce seizures. The videos were graded using the Racine scale and the root-mean-square (RMS) power analysis of EEG was performed with Sirenia Seizure Pro software. We found that the RMS power was very weakly correlated with convulsive behavior induced by pilocarpine. Convulsive behaviors appeared long before electrographic seizures and showed a strong negative correlation with theta frequency activity and a moderate positive correlation with gamma frequency activity. Racine scores showed moderate correlations with RMS power across multiple frequency bands during the transition from first electrographic seizure to SE. However, there was no correlation between Racine scores and RMS power during the SE phase except a weak correlation with RMS power in the theta frequency. Our analysis reveals limitations of the Racine scale as a primary index of seizure intensity in status epilepticus, and demonstrates a need for quantitative analysis of EEG for an accurate assessment of seizure onset and severity.


Theoretical Biology and Medical Modelling | 2007

Hypertabastic survival model

Mohammad A. Tabatabai; Zoran Bursac; David K. Williams; Karan P. Singh

A new two-parameter probability distribution called hypertabastic is introduced to model the survival or time-to-event data. A simulation study was carried out to evaluate the performance of the hypertabastic distribution in comparison with popular distributions. We then demonstrate the application of the hypertabastic survival model by applying it to data from two motivating studies. The first one demonstrates the proportional hazards version of the model by applying it to a data set from multiple myeloma study. The second one demonstrates an accelerated failure time version of the model by applying it to data from a randomized study of glioma patients who underwent radiotherapy treatment with and without radiosensitizer misonidazole. Based on the results from the simulation study and two applications, the proposed model shows to be a flexible and promising alternative to practitioners in this field.


Therapeutic Advances in Cardiovascular Disease | 2012

Atrial fibrillation following autologous stem cell transplantation in patients with multiple myeloma: incidence and risk factors

Ravi Sureddi; Fariba Amani; Prabhat Hebbar; David K. Williams; Marino Leonardi; Hakan Paydak; Jawahar L. Mehta

Objectives: Atrial fibrillation (AF) often develops in patients with multiple myeloma following autologous stem cell transplantation (ASCT), but the exact incidence of, and the risk factors for AF have not been described. In this study, we sought to determine the incidence of AF in patients with multiple myeloma undergoing ASCT. Methods: Patients who received ASCT for multiple myeloma between January 2000 and December 2009 were identified using the ICD-9 codes for multiple myeloma and ASCT, and formed the basis of this report. Results: The study included 278 patients (mean age, 63 ± 9.5 years). A total of 75 (27%) patients developed AF at a mean duration of 14.8 days following ASCT. On multiple regression analysis, baseline renal dysfunction (odds ratio 15.2 [confidence interval 5.08–45.6]), left ventricular systolic dysfunction (9.55 [2.78–32.79]), dilated left atrium on echocardiogram (4.97 [1.8–13.78]), and hypertension (3.6 [1.36–9.52]) were significantly associated with the development of AF after ASCT. The presence of light-chain secretion (0.21 [0.07–0.6]) was associated with a lower incidence of AF. Age, gender, and race were not significantly associated with the development of AF after ASCT. Conclusions: AF is very frequent in patients with multiple myeloma when they receive ASCT. The presence of abnormal renal function, left ventricular systolic dysfunction, dilated left atrium, or hypertension at baseline identifies patients at high risk of developing AF following ASCT.


Journal of Pharmacology and Experimental Therapeutics | 2011

The Fate and Function of Therapeutic Antiaddiction Monoclonal Antibodies across the Reproductive Cycle of Rats

Jonathan J. Hubbard; Elizabeth M. Laurenzana; David K. Williams; William Brooks Gentry; S M Owens

During preclinical development of neuroprotective antiaddiction therapeutic monoclonal antibodies (mAbs) against phencyclidine (PCP) and (+)-methamphetamine, we discovered novel, gestation stage-specific changes in mAb disposition spanning the entire reproductive cycle of female rats. Each pharmacological change was independent of mAb dose and antigen target but was precisely coincident with transitions between the gestational trimesters, parturition, and lactation periods of the female reproductive cycle. Whereas anti-PCP mAb6B5 terminal elimination half-life (t1/2λz) in nonpregnant females was 6.6 ± 1.6 days, the mAb6B5 t1/2λz significantly changed to 3.7 ± 0.4 days, then 1.4 ± 0.1 days, then 3.0 ± 0.4 days in the second trimester, third trimester, and postpartum periods, respectively (p < 0.05 for each change). Initially, these evolving changes in mAb6B5 clearance (3.3-fold), distribution volume (1.8-fold), and elimination half-life (4.7-fold) affected our ability to sustain sufficient mAb6B5 levels to sequester PCP in the bloodstream. However, understanding the mechanisms underlying each transition allowed development of an adaptive mAb-dosing paradigm, which substantially reduced PCP levels in dam brains and fetuses throughout pregnancy. These mAb functional studies also revealed that antidrug mAbs readily cross the placenta before syncytiotrophoblast barrier maturation, demonstrating the dynamic nature of mAb pharmacokinetics in pregnancy and the importance of maintaining maternal mAb levels. These studies provide the first preclinical pregnancy model in any species for chronic mAb dosing and could have important implications for the use of antibody therapies involving blood organ barriers (such as addiction) or other chronic diseases in women of childbearing age (e.g., irritable bowel diseases, multiple sclerosis, breast cancer, rheumatoid arthritis).


Drug Metabolism and Disposition | 2014

Treatment with a monoclonal antibody against methamphetamine and amphetamine reduces maternal and fetal rat brain concentrations in late pregnancy.

Sarah J. White; Howard P. Hendrickson; William T. Atchley; Elizabeth M. Laurenzana; William Brooks Gentry; David K. Williams; S M Owens

We hypothesized that treatment of pregnant rat dams with a dual reactive monoclonal antibody (mAb4G9) against (+)-methamphetamine [METH; equilibrium dissociation rate constant (KD) = 16 nM] and (+)-amphetamine (AMP; KD = 102 nM) could confer maternal and fetal protection from brain accumulation of both drugs of abuse. To test this hypothesis, pregnant Sprague-Dawley rats (on gestational day 21) received a 1 mg/kg i.v. METH dose, followed 30 minutes later by vehicle or mAb4G9 treatment. The mAb4G9 dose was 0.56 mole-equivalent in binding sites to the METH body burden. Pharmacokinetic analysis showed baseline METH and AMP elimination half-lives were congruent in dams and fetuses, but the METH volume of distribution in dams was nearly double the fetal values. The METH and AMP area under the serum concentration-versus-time curves from 40 minutes to 5 hours after mAb4G9 treatment increased >7000% and 2000%, respectively, in dams. Fetal METH serum did not change, but AMP decreased 23%. The increased METH and AMP concentrations in maternal serum resulted from significant increases in mAb4G9 binding. Protein binding changed from ∼15% to > 90% for METH and AMP. Fetal serum protein binding appeared to gradually increase, but the absolute fraction bound was trivial compared with the dams. mAb4G9 treatment significantly reduced METH and AMP brain values by 66% and 45% in dams and 44% and 46% in fetuses (P < 0.05), respectively. These results show anti-METH/AMP mAb4G9 therapy in dams can offer maternal and fetal brain protection from the potentially harmful effects of METH and AMP.

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Bill J. Gurley

University of Arkansas for Medical Sciences

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William Brooks Gentry

University of Arkansas for Medical Sciences

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Zoran Bursac

University of Tennessee Health Science Center

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Elizabeth M. Laurenzana

University of Arkansas for Medical Sciences

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S M Owens

University of Arkansas for Medical Sciences

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Dinesh Mittal

University of Arkansas for Medical Sciences

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Edgar Garcia-Rill

University of Arkansas for Medical Sciences

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Jeffrey M. Pyne

University of Arkansas for Medical Sciences

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