Independence is key to better regulation.
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Accreditation↗
Biomedical subjects
James Johnson
Publications and source records attributed to James Johnson.
Determination of respiratory phase during acquisition of airway cine MR images.
Subjects were imaged on a 1.5-T Signa MRI system using the head-neck vascular coil. An axial fast gradient echo cine, at the base of the second cervical vertebra, was obtained. A total of 128 images were acquired with a rapid image acquisition (one per second) over several respiratory cycles. The analog signal from the MR scanner (RF unblank) was utilized to determine the duration of the cine MR sequence. The phase of respiration was determined by analyzing the nasal air flow connected via pressure tubing to a pressure transducer outside the MR scanner room. We were thus able to determine the phase of respiration during acquisition of individual airway cine MR images. There was a wide range of airway volume measurements over the respiratory cycle with the lowest volume at end expiration and the highest at peak inspiration.
Adolescent↗
Broadband learning for doctors.
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Education, Distance↗
Marked intraindividual variability in antiretroviral concentrations may limit the utility of therapeutic drug monitoring.
BACKGROUND: Effective therapeutic drug monitoring for antiretrovirals requires a better understanding of intraindividual variability in pharmacokinetics. METHODS: We determined concentrations of human immunodeficiency virus (HIV) protease and nonnucleoside reverse-transcriptase inhibitors for 10 patients with undetectable plasma HIV RNA levels who had been receiving stable regimens for > or = 11 months. Plasma samples were collected at the same time of day 3 times per week for up to 4 months. Patients were instructed to take their antiretrovirals at the same time every day. Plasma protease and nonnucleoside reverse-transcriptase inhibitor concentrations were determined using high-performance liquid chromatographic methods. Pharmacokinetic variability was expressed as intraindividual percentage coefficient of variation (ICV), which was calculated as the patient's standard deviation divided by the mean drug concentration for that patient. RESULTS: ICV was determined for 6 drugs for 10 patients, for a total of 17 different patient-drug combinations, using 600 total samples. ICV was unexpectedly high for most patients who were receiving protease inhibitors (ICVs for individual patients taking lopinavir/ritonavir were 24%, 33%, 51%, and 92%; for patients taking nelfinavir/M8 metabolite, they were 30%/44% and 39%/54%; for patients taking ritonavir, they were 34% and 43%; for patients taking saquinavir, they were 52% and 55%). ICVs for patients receiving nonnucleoside reverse-transcriptase inhibitors were lower (for patients receiving efavirenz, they were 7%, 13%, 29%, and 51%; for a patient receiving nevirapine, it was 25%). The median ICV for all patients receiving protease inhibitors (n = 12) was 43.5%, and for all patients receiving nonnucleoside reverse-transcriptase inhibitors (n = 5), the median ICV was 25%. CONCLUSIONS: Intraindividual variability in concentrations of antiretrovirals was surprisingly high in virologically suppressed patients. Possible contributors include food effects, concomitant use of prescription and herbal medications, assay variability, or medication timing, which was assessed by self-report. High intraindividual pharmacokinetic variability may limit the utility of single measurements in therapeutic drug monitoring for some antiretroviral agents.
Acquired Immunodeficiency Syndrome↗
Detection and quantification of protein biomarkers from fewer than 10 cells.
The use of antibody microarrays continues to grow rapidly due to the recent advances in proteomics and automation and the opportunity this combination creates for high throughput multiplexed analysis of protein biomarkers. However, a primary limitation of this technology is the lack of PCR-like amplification methods for proteins. Therefore, to realize the full potential of array-based protein biomarker screening it is necessary to construct assays that can detect and quantify protein biomarkers with very high sensitivity, in the femtomolar range, and from limited sample quantities. We describe here the construction of ultramicroarrays, combining the advantages of microarraying including multiplexing capabilities, higher throughput, and cost savings with the ability to screen very small sample volumes. Antibody ultramicroarrays for the detection of interleukin-6 and prostate-specific antigen (PSA), a widely used biomarker for prostate cancer screening, were constructed. These ultramicroarrays were found to have a high specificity and sensitivity with detection levels using purified proteins in the attomole range. Using these ultramicroarrays, we were able to detect PSA secreted from 100 LNCaP cells in 3 h and from just four LNCaP cells in 24 h. Cellular PSA could also be detected from the lysate of an average of just six cells. This strategy should enable proteomic analysis of materials that are available in very limited quantities such as those collected by laser capture microdissection, neonatal biopsy microspecimens, and forensic samples.
Biomarkers↗
Normal immune development and glucocorticoid-induced thymocyte apoptosis in mice deficient for the T-cell death-associated gene 8 receptor.
T-cell death-associated gene 8 (TDAG8) is a G-protein-coupled receptor transcriptionally upregulated by glucocorticoids (GCs) and implicated by overexpression studies in psychosine-mediated inhibition of cytokinesis and in GC-induced apoptosis. To examine the physiological function of TDAG8, we generated knockout (KO) mice by homologous recombination. An enhanced green fluorescent protein reporter was knocked into the disrupted tdag8 locus to allow the analysis of TDAG8 expression in living cells. Interestingly, we found that during thymocyte development, TDAG8 expression resembled the dynamic regulation described for known modulators of GC-induced apoptosis, including Bcl-2, Notch1, and GC receptor. TDAG8 was expressed in double-negative cells, was downregulated at the double-positive transition, and was upregulated in single-positive thymocytes. However, despite this striking expression pattern, maturation and selection of thymocytes, as well as major immune functions, were not affected in TDAG8 KO mice. In contrast to previous overexpression results, TDAG8 was dispensable for psychosine-induced formation of multinucleated cells. Furthermore, TDAG8 KO thymocytes showed normal apoptosis following in vivo and in vitro GC treatment. These results, while establishing a useful reporter strain to study T-lymphocyte maturation, argue against a critical role for TDAG8 in immune development, psychosine-mediated inhibition of cytokinesis, and GC-induced cell death.
Animals↗
Pharmacokinetics of buprenorphine after intravenous administration in the mouse.
Buprenorphine is a potent partial m-opioid agonist that is used as an analgesic in animals and humans to ameliorate moderate to severe pain and in the treatment of opiate addiction as an alternative to methadone maintenance. The purpose of this study was to characterize the pharmacokinetics of buprenorphine after intravenous administration in mice. Mice (n=48) were given 2.4 mg/kg buprenorphine (HCl salt) by intravenous bolus injection, and groups of 4 mice were euthanized at 5, 15, and 30 min and 1, 2, 3, 5, 7, 9, 12, 18, and 24 h after drug administration. Plasma concentrations of buprenorphine and norbuprenorphine were determined using liquid chromatography-tandem mass spectrometry. By using the mean concentrations at each time point (n=4), pharmacokinetic parameters were estimated for buprenorphine using a 3-compartment model with the reciprocal of the predicted concentration as the weight factor. The estimated values for the exponents of the 1st, 2nd, and terminal compartments; volume of distribution at steady state; clearance; and area under the concentration-time curve were 12.8/h, 2.13/h, 0.239/h, 6.5 l/kg, 4.3 l/h/kg, and 559 microg/lxh, respectively. In addition, we compare the pharmacokinetic disposition of buprenorphine in the mouse with that previously reported for other species.
Analgesics, Opioid↗
Stopping Africa's medical brain drain.
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Africa South of the Sahara↗
The GMC: expediency before principle: BMA chairman responds.
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Accreditation↗
High-dose chemotherapy with autologous stem-cell rescue in the treatment of patients with recurrent non-cerebellar primitive neuroectodermal tumors.
BACKGROUND: Recurrent non-cerebellar primitive neuroectodermal tumors (PNETs) carry a dismal prognosis when treated with conventional chemotherapy alone. XSWe tested the efficacy of high-dose chemotherapy (HDC) followed by autologous stem-cell rescue (ASCR) in this setting. PROCEDURE: Eligibility mandated either minimal residual disease or evidence of chemosensitivity before HDC. Conditioning consisted of carboplatin (CBDCA) (500 mg/m(2) or AUC = 7 mg/ml min using the Calvert formula) on days -8 to -6, thiotepa (300 mg/m(2)), and etoposide (250 mg/m(2)) on days -5 to -3. Irradiation was given post HDC selectively. RESULTS: Among 17 patients treated in this study, there were eight pineoblastoma(s) (pineo), seven cortical PNETs, and two arising elsewhere. Relapse was either local (nine) or metastatic to the brain (four) or spine (four). Two patients received HDC as the sole therapy for recurrence; additionally, eight underwent surgical debulking before HDC, and nine received irradiation, including six after HDC. Median age at ASCR was 3.9 years. Two patients died of toxicity (11%) and ten experienced tumor relapse (range: 23-361 days post ASCR). Five patients with cortical PNETs remain alive disease-free (median follow-up: 8.3 years); four of them received irradiation post HDC. The difference in 5-year event-free survival (EFS) between patients with pineo and other supratentorial PNETs was significant (0 vs. 62.5 +/- 17%, P = 0.0065). Both surgery at relapse and irradiation post HDC were favorable prognostic factors (P = 0.006 and 0.01, respectively). CONCLUSIONS: Patients with recurrent cortical PNETs can be cured with this strategy. Surgical debulking before, and irradiation after HDC play an important role in treatment success.
Adolescent↗
Functional protein nanoarrays for biomarker profiling.
The use of microarrays for parallel screening of nucleic acid profiles has become an industry standard. Similar efforts for screening protein-protein interactions are gaining momentum, however, they remain limited by the requirement for relatively large sample volumes. One strategy for overcoming this problem is to significantly decrease the size and consequently the sample volume of the protein interaction assay. We report here on our progress over the last two years in the construction of ultraminiaturized, functional protein capture assays. Each one micron spot in these array-based assays covers less than 1/1000(th) of the surface area of a conventional microarray spot while still maintaining enough antibodies to provide a useful dynamic range. These nanoarray assays can be read by conventional optical fluorescence microscopy as well as by novel label-free methods such as atomic force microscopy. The size reduction realized by functional protein nanoarrays also creates opportunities for novel applications including highly multiplexed single cell analysis and integration with microfluidics and other "lab-on-a-chip" technologies.
Biomarkers↗
Back-seat driver. Interview by Sarah Grant.
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Contract Services↗
Iliac crest osteocutaneous flap reconstruction for ameloblastoma of the mandible in a patient with bilateral peronea artery magna: case report.
Success of oromandibular reconstructions is increasingly achieved through fundamental microvascular techniques that incorporate innovative adjunct modalities. We report a complex case of a large anterior mandibular plexiform ameloblastoma reconstructed with an iliac crest free flap in a young woman with bilateral peronea arteria magna. This article serves to highlight the application of several new technologies in an effort to provide a functional and cosmetically acceptable result.
Adult↗
wCLUTO: a Web-enabled clustering toolkit.
As structural and functional genomics efforts provide the biological community with ever-broadening sets of interrelated data, the need to explore such complex information for subtle relationships expands. We present wCLUTO, a Web-enabled version of the stand-alone application CLUTO, designed to apply clustering methods to genomic information. Its first application is focused on the clustering transcriptome data from microarrays. Data can be uploaded by the user into the clustering tool, a choice of several clustering methods can be made and configured, and data are presented to the user in a variety of visual formats, including a three-dimensional "mountain" view of the clusters. Parameters can be explored to rapidly examine a variety of clustering results, and the resulting clusters can be downloaded either for manipulation by other programs or to be saved in a format for publication.
Algorithms↗
Influence of site preparation methods on the pain reported during palatal infiltration using the Wand Local Anesthetic System.
PURPOSE: To compare different site preparation methods and their effect on the pain reported during local anesthetic infiltration at the palatal site. The study compared the following tissue site preparation methods: application of a topical anesthetic agent, pressure anesthesia achieved with a cotton tip applicator, a combination of both methods, and neither method (non-placebo control). MATERIALS AND METHODS: 15 adult subjects received a total of four palatal injections, one with each type of site preparation in a randomized order over two appointments (two injections per appointment). Bilateral palatal injections were performed in a standardized manner using the uniform slow flow rate produced by the Wand Local Anesthetic System through a 30-gauge needle. Pain response was measured by subject self-report using the visual analogue scale (VAS), a quantified verbal descriptor scale (Gracely), and a comparison to prior injection experience, as well as the operator's global assessment of the subject's pain response. RESULTS: All recorded pain measurements failed to demonstrate statistical differences for the various site preparations tested. The scores for the VAS and the Gracely scales were statistically in agreement. When administering a slow flow rate of anesthetic solution at the palatal site, this study demonstrated that the intensity of pain reported by adult subjects was minimal. The low intensity of reported pain, measured in several different ways, failed to discriminate among the various site preparation methods tested.
Administration, Topical↗
All-ceramic restorative system for esthetic implant-supported crowns: in vitro evaluations and clinical case report.
Patient demands for improved esthetics have prompted the development of all-ceramic restorative systems for dental implants, but material strength and restorative costs have presented clinical challenges. Therefore, a new restorative system with tooth-shaped ceramic copings for the anterior and premolar jaw regions has been introduced to address these problems. Fatigue and 17o. compression tests were conducted in vitro to assess the mechanical strength of the 6 tooth-shaped copings and several luting agents of the system. A case report on the clinical use of the components is presented. All 6 tooth-shaped copings significantly exceeded the range of forces associated with restoration in the anterior jaw. Crown-endurance limits for fatigue and 17o. compression were 70% higher and 46% higher, respectively, than the established minimum-fatigue-endurance limits in those categories. In clinical evaluation, the ceramic restorative system performed well and produced excellent results; it has potential for implant restorations in the anterior and premolar regions of the jaw.
Aluminum Oxide↗
Patients should receive copies of letters and summaries.
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Communication↗
Phytanic acid, a natural peroxisome proliferator-activated receptor (PPAR) agonist, regulates glucose metabolism in rat primary hepatocytes.
Phytanic acid, a metabolite of the chlorophyll molecule, is part of the human diet and is present in normal human serum at low micromolar concentrations. It was previously shown to be a ligand of the 9-cis-retinoic acid receptor and peroxisome proliferator-activated receptor (PPAR) a. PPAR agonists are widely used in the treatment of type 2 diabetes. Here, we report that phytanic acid is not only a transactivator of PPARa, but it also acts via PPARb and PPARg in CV-1 cells that have been cotransfected with the respective full-length receptor and an acyl-CoA oxidase-PPAR-responsive element-luciferase construct. We observed that, in contrast to other fatty acids, phytanic acid at physiological concentrations enhances uptake of 2-deoxy-D-glucose in rat primary hepatocytes. This result could be explained by the increase in mRNA expression of glucose transporters-1 and -2 and glucokinase, as determined by quantitative real-time reverse transcriptase-polymerase chain reaction. Compared with the PPARg-specific agonist ciglitazone, phytanic acid exerts only minor effects on the differentiation of C3H10T1/2 cells into mature adipocytes. These results clearly demonstrate that phytanic acid acts via different PPAR isoforms to modulate expression of genes involved in glucose metabolism, thus suggesting a potential role of phytanic acid in the management of insulin resistance.
Adipocytes↗