Biomedical subjects

Dennis Parker

Publications and source records attributed to Dennis Parker.

11 recordsLinked to original sources

PubMed2026

Identifying stakeholder behaviors for competency-based pharmacy education: A stage 1 behavior change wheel analysis.

INTRODUCTION/OBJECTIVES: Competency-Based Pharmacy Education (CBPE) is a strategic priority for preparing graduates to meet evolving healthcare needs. However, efforts to implement CBPE can stall due to behavioral challenges among faculty, administrators, preceptors, and learners. This study aimed to apply Stage 1 of the Behavior Change Wheel (BCW) to identify stakeholder-specific behaviors and associated determinants needed to implement the five core components of CBPE. METHODS: A multi-method approach grounded in the BCW, the Capability, Opportunity, Motivation - Behavior (COM-B) model, and the Theoretical Domains Framework (TDF) was used. Data were gathered through (1) targeted literature review; (2) structured focus groups with competency-based education experts and pharmacy education stakeholders; and (3) an iterative consensus process. Behaviors were mapped to the five CBPE components: (1) defined competencies, (2) developmental progression, (3) tailored instruction, (4) authentic experiential learning, and (5) programmatic assessment, and then mapped to COM-B and TDF constructs. RESULTS: Over fifty stakeholder-specific behaviors were identified and specified across the CBPE framework. This revealed shared barriers such as limited instructional design knowledge (psychological capability), insufficient assessment of infrastructure (physical opportunity), and misaligned professional identity (reflective motivation). Key TDF domains included knowledge, environmental context, beliefs about capabilities, and professional roles. The behavioral problem statements, specifications, and determinants were identified to support future intervention planning. CONCLUSION: This Stage 1 analysis provides a behaviorally grounded foundation for CBPE implementation by identifying stakeholder behaviors and conditions that enable change. These findings will inform the development of readiness-to-change assessments and targeted interventions (BCW Stages 2 and 3), supporting scalable and sustainable CBPE transformation in pharmacy education.

Education, Pharmacy↗

PubMed2006

MR thermometry-based feedback control of efficacy and safety in minimum-time thermal therapies: phantom and in-vivo evaluations.

The experimental validation of a model-based, thermal therapy control system which automatically and simultaneously achieves the specified efficacy and safety objectives of the treatment is reported. MR-thermometry measurements are used in real-time to control the power of a stationary, focused ultrasound transducer in order to achieve the desired treatment outcome in minimum time without violating the imposed safety constraints. Treatment efficacy is quantified in terms of the thermal dose delivered to the target. Normal tissue safety is ensured by automatically maintaining normal tissue temperature below the imposed limit in the user-specified locations. To reflect hardware limitations, constraints on the maximum applied power are also imposed. At the pretreatment stage, MR imaging and thermometry are used to localize the treatment target and identify thermal and actuation models. The results of phantom and canine experiments demonstrate that spatially-distributed, real-time MR temperature measurements enhance one's ability to robustly achieve the desired treatment outcome in minimum time without violating safety constraints. Post-treatment evaluation of the outcome using T2-weighted images of canine muscle showed good spatial correlation between the sonicated area and thermally damaged tissue.

Animals↗

PubMed2006

Considerations in fluids and electrolytes after traumatic brain injury.

Appropriate fluid management of patients with traumatic brain injury (TBI) presents a challenge for many clinicians. Many of these patients may receive osmotic diuretics for the treatment of increased intracranial pressure or develop sodium disturbances, which act to alter fluid balance. However, establishment of fluid balance is extremely important for improving patient outcomes after neurologic injury. The use of hyperosmolar fluids, such as hypertonic saline, has gained significant interest because they are devoid of dehydrating properties and may have other beneficial properties for patients with TBI. Electrolyte derangements are also common after neurologic injury, with many having neurologic manifestations. In addition, the role of electrolyte abnormalities in the secondary neurologic injury cascade is being delineated and may offer a potential future therapeutic intervention.

Brain Edema↗

PubMed2005

Examination of ELN as a candidate gene in the Utah intracranial aneurysm pedigrees.

BACKGROUND AND PURPOSE: A study of intracranial aneurysm (IA) sibpairs suggested association of an ELN haplotype with IA risk. Subsequent linkage analysis of the ELN region on chromosome 7q11 in high-risk Utah IA pedigrees significantly confirmed linkage between IA and the ELN region. METHODS: We have investigated the ELN gene as a potential candidate gene for IA in Utah pedigrees. One IA case from each pedigree, who shared an ELN region haplotype segregating in the pedigree, was screened for mutation. The promoter region, 34 exons, and the 3'UTR (UnTranslated Region) of the ELN gene were screened for variants using DHPLC. RESULTS: Variants were observed in the promoter region, exons 4 and 6, and the 3'UTR. Variants in exon 6 and in one 3'UTR position were unique to Utah. The remaining variants were absent in the controls. There was no evidence for segregation of the ELN variants found in IA cases with the hypothesized chromosome 7 haplotypes segregating in pedigrees. CONCLUSIONS: Our analysis does not support ELN as the gene responsible for familial IA in the linked Utah IA pedigrees.

3' Untranslated Regions↗

PubMed2005

Thrombolysis for intraventricular hemorrhage after endovascular aneurysmal coiling.

OBJECTIVE AND IMPORTANCE: Current applications of lytic therapy for intraventricular hemorrhage (IVH) rely on exclusion of vascular abnormalities as etiology. Its use in patients with recently coiled aneurysms remains far from considered safe. We report a patient with subarachnoid hemorrhage (SAH) and massive IVH from aneurysmal rupture, which was safely treated with intraventricular recombinant tissue plasminogen activator (rt-PA) after endovascular coiling. We also review two other similar cases reported in the literature. CLINICAL PRESENTATION: A 61-year-old man presented with a ruptured anterior communicating artery aneurysm causing SAH and IVH (Hunt & Hess grade IV, Fisher grade III with IVH). During coiling of the aneurysm, extravasation of contrast was noted on fluoroscopy. Follow-up head computed tomography (CT) scan showed casted ventricles. Once in the intensive care unit, the patient progressed to coma, which did not improve with external ventricular drainage alone. INTERVENTION: After endovascular coiling of the aneurysm, intraventricular rt-PA was administered. Isovolemic injections of 2 mg rt-PA every 12 hours were performed for a total of four doses. No clinical or radiological evidence of worsening SAH/IVH was documented. At the time of discharge, the patient was awake but requiring assistance with activities of daily living. CONCLUSION: We report the safe administration of intraventricular rt-PA after endovascular coiling of a ruptured cerebral aneurysm. Two other similar cases were found in the literature and are reviewed. Hindrance of aneurysmal cavity thrombosis by early administration of rt-PA (increasing the risk of rerupture) remains a widespread concern. The lack of such instances should therefore be acknowledged. We propose that inclusion of such patients in trials assessing safety/efficacy of thrombolytic therapy in the treatment of patients with intracranial hemorrhage should be carefully considered.

Cerebral Angiography↗

PubMed2004

The arthrotropism of macromolecules in adjuvant-induced arthritis rat model: a preliminary study.

PURPOSE: To study the accumulation of macromolecules into the arthritic joints and the possible applications of such phenomenon. METHODS: The accumulation of plasma albumin in the joints of adjuvant-induced arthritis (AIA) rat model was first visualized with Evans blue injection. A N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer contrast agent was then synthesized and injected into the AIA rats to allow qualitative examination of biodistribution and pharmacokinetics of the injected macromolecule with magnetic resonance imaging (MRI). Vital organs and the diseased joints were isolated and examined histologically to correlate with the MRI findings. RESULTS: Deep blue color developed around the arthritic joints of the AIA rat a few hours after the injection of Evans blue. MR imaging of the AIA rats injected with polymer contrast agent demonstrated a gradual but very strong accumulation of the injected polymer in the arthritic joints, which lasted for 1-2 days. Observed differences in the concentration of the injected polymer in the joints correlated with disease severity as assessed histologically. CONCLUSIONS: Profound arthrotropism of macromolecules in the AIA rat model was demonstrated with various imaging tools. These observations should help in the conceptual and practical design of novel macromolecular delivery systems for the imaging and treatment of rheumatoid arthritis.

Animals↗

PubMed2004

Introducing hypertonic saline for cerebral edema: an academic center experience.

INTRODUCTION: Use of hypertonic saline (HTS) is gaining acceptance in the neurosciences critical care unit (NCCU) based on its efficacy in reducing cerebral edema and its favorable hemodynamic profile. In the NCCU, unfamiliarity with the use of HTS may result in implementation difficulties. We report our initial experience using HTS, its ability to achieve a hypernatremic state, and adverse effects. METHODS: Analysis of 19 consecutive patients who were admitted to the NCCU and treated with 2 or 3% HTS infusion for cerebral edema (target serum sodium: 145-155 mEq/L) included patient diagnoses, laboratory data, length of treatment, adverse effects, and outcome at discharge. We compared the adverse effects of those patients to a contemporary cohort of patients who received mannitol as the sole form of osmotherapy. RESULTS: The HTS cohort had a median age of 46 years (range: 18-70). Median GCS and APACHE II scores were 11 (range: 3-15) and 18 (range: 8-30), respectively. Median length of HTS treatment was 5 days (range: 1-17). Target hypernatremia was achieved in 14 patients (74%), 7 of whom achieved hypernatremia within the first 24 hours. The median number of rescue interventions received for ICP control was 3 (range: 1-30). The adverse effects between the HTS and mannitol cohorts were not found to be significantly different. CONCLUSION: The use of HTS for cerebral edema requires intensive efforts by the medical team to rapidly achieve and maintain a hypernatremic state. The continuous infusion of HTS was used safely.

Academic Medical Centers↗

PubMed2003

Confirmation of chromosome 7q11 locus for predisposition to intracranial aneurysm.

A significant linkage of intracranial aneurysm (IA) has recently been reported to chromosomal region 7q11 (MLS=3.22) in a genomic search of 85 Japanese nuclear families with at least two affected siblings (104 sib pairs). This region contains the elastin gene (ELN, OMIM 130160), which is a functional candidate gene for IA. We have replicated this finding through linkage analyses in 13 extended pedigrees from Utah, comprising 39 IA cases. We genotyped three markers flanking ELN and performed two-point and multipoint parametric analyses, employing simple dominant and recessive models. Analyses utilizing a recessive affecteds-only model yielded significant confirmation of linkage to the region (best evidence, multipoint TLOD=2.34, at D7S2421, corrected P=0.001). This study is the first to confirm the linkage of the 7q11 locus for IA.

Chromosomes, Human, Pair 7↗

PubMed2003

CTA and MRA: visualization without catheterization.

The ideal modality for vascular imaging would be noninvasive and inexpensive. A volumetric acquisition would permit visualization of vessels from arbitrary angles. High contrast between the vessel lumen and background tissue would be coupled with excellent spatial resolution allowing accurate depiction of small vessels. Characterization of the constituent components of the vessel wall would be possible. High temporal resolution would both freeze the motion of fast moving vessels and show the direction and speed of blood flow. Finally, the modality would expose the patient to a minimal amount of ionizing radiation or potentially toxic contrast agents. Diagnostic conventional catheter angiography offers unsurpassed spatial and temporal resolution. However, catheter angiography is an interventional procedure, exposes the patient to both ionizing radiation and iodinated contrast, and does not depict the vessel wall. Additionally, view angles are chosen before the administration of contrast and may not demonstrate certain lesions. These limitations have driven the development of both computed tomography angiography (CTA) and magnetic resonance angiography (MRA). Both of these modalities rapidly acquire volumetric data sets, which can then be evaluated slice by slice or by more advanced volumetric rendering techniques. CTA and MRA are minimally invasive and less costly than angiography. While CTA and MRA cannot compete with the spatial or temporal resolution of conventional angiography, present technology has proven clinical efficacy in a wide range of applications. The principles behind CTA and MRA and their comparative strengths and weaknesses will be discussed. The different volumetric rendering techniques will be reviewed. Finally, recent advances that will likely further improve these modalities will be summarized.

Angiography↗

PubMed2003

Disposition of cefepime in the central nervous system of patients with external ventricular drains.

STUDY OBJECTIVE: To assess central nervous system (CNS) penetration of cefepime in adults with external ventricular drains and to compare the achieved cerebrospinal fluid (CSF) concentrations with the usual minimum inhibitory concentrations (MICs) of common pathogens. DESIGN: Open-label, prospective study. SETTING: University-affiliated medical center. PATIENTS: Seven patients with external ventricular drains and normal renal function (documented creatinine clearance > 60 ml/min) who received cefepime 2 g intravenously every 12 hours for treatment of nosocomial pneumonia. INTERVENTION: Serial serum and CSF samples were obtained concurrently after the fourth dose during one dosing interval. MEASUREMENTS AND MAIN RESULTS: The concentration-time profiles in serum and CSF were comodeled by using a two-compartment model with zero-order infusion to the central compartment. The CSF concentration-time profiles of the individual patients were compared with published MIC90 of common pathogens isolated in nosocomial meningitis. Our model reasonably characterized the disposition of cefepime in serum and CSF. Penetration into the CNS was 4-34% based on area under the curve and was 5-58% based on minimum concentration. CONCLUSION: Penetration of cefepime into the CNS was variable among the patients (4-34%) but appeared similar to that reported for other cephalosporins given to treat meningitis. The concentrations attained by most patients in this study were above the MIC90 of many common nosocomial organisms.

Adult↗

PubMed2002

Tolerability of bolus versus continuous gastric feeding in brain-injured patients.

Brain injured patients may exhibit altered gastric emptying; thus, some believe post-pyloric feeding to be tolerated better than gastric feeding. Reliable post-pylorus access can be difficult to obtain, so gastric feeding remains the preferred route for administering nutrition. Feeding intolerance may be associated with increased complications and costs. We sought to compare bolus (B) versus continuous (C) gastric feeding in brain injured patients. This retrospective cohort study was carried out at a neurological/neurosurgical intensive care unit at a Level 1 trauma and tertiary referral center. Our subjects were 152 consecutive patients over two years. Use of B or C feedings was based on clinicians' preferences. Abdominal examination and gastric residuals (> 75 mL over four hours) defined feeding intolerance (FI). Putative risks for FI were compared between the groups. Demographic characteristics were similar between groups B (n = 86) and C (n = 66). Feeding intolerance occurred more often in group B than in group C (60.5% vs. 37.9%, p = 0.009). Group C patients achieved 75% of nutritional goals faster than group B patients (median 3.3 vs. 4.6 days; p = 0.03). Prokinetic agent use was similar between the groups and did not reduce the time to achieve nutritional goals. There was a trend towards a reduction in the incidence of infections in group C (p = 0.05). Independent predictors of FI included: sucralfate (OR 2.3), propofol (OR 2.1), pentobarbital (OR 3.9) or paralytic (OR 3) use; older age (OR 5); days receiving mechanical ventilation (OR 1.2); and admission diagnosis of either intracerebral hemorrhage (OR 2.2) or ischemic stroke (OR 1.9). Continuous gastric feeding is better tolerated than B feedings in patients with acute brain injuries. Use of prokinetic agents did not affect time to achievement of nutritional goals. Use of common medications including sucralfate and propofol were associated with FI.

Adjuvants, Anesthesia↗