Teaching of drug disposition using physiologically based pharmacokinetic modeling software: GastroPlus as an educational tool.

Physiologically based pharmacokinetic (PBPK) modeling requires an understanding of chemical, physiologic, and pharmacokinetic principles. Active learning with PBPK modeling software (GastroPlus) may be useful to teach these scientific principles while also teaching software operation. To examine this issue, a graduate-level course was designed using learning objectives in science, software use, and PBPK model application. These objectives were taught through hands-on PBPK modeling to answer clinically relevant questions. Students demonstrated proficient use of software, based on their responses to these questions, and showed an improved understanding of scientific principles on a pre- and post-course assessment. These outcomes support the effectiveness of simultaneous teaching of interdependent software and science.NEW & NOTEWORTHY Physiologically based pharmacokinetic (PBPK) modeling is a major growth area in drug development, regulatory submissions, and clinical applications. There is a demand for experts in this area with multidisciplinary backgrounds. In this article, we describe a course designed to teach PBPK modeling and the underlying scientific principles in parallel.

Disruption of the Atrophy-based Functional Network in Multiple Sclerosis Is Associated with Clinical Disability: Validation of a Meta-Analytic Model in Resting-State Functional MRI.

Background In multiple sclerosis (MS), gray matter (GM) atrophy exhibits a specific pattern, which correlates strongly with clinical disability. However, the mechanism of regional specificity in GM atrophy remains largely unknown. Recently, the network degeneration hypothesis (NDH) was quantitatively defined (using coordinate-based meta-analysis) as the atrophy-based functional network (AFN) model, which posits that localized GM atrophy in MS is mediated by functional networks. Purpose To test the NDH in MS in a data-driven manner using the AFN model to direct analyses in an independent test sample. Materials and Methods Model fit testing was conducted with structural equation modeling, which is based on the computation of semipartial correlations. Model verification was performed in coordinate-based data of healthy control participants from the BrainMap database (https://www.brainmap.org). Model validation was conducted in prospectively acquired resting-state functional MRI in participants with relapsing-remitting MS who were recruited between September 2018 and January 2019. Correlation analyses of model fit indices and volumetric measures with Expanded Disability Status Scale (EDSS) scores and disease duration were performed. Results Model verification of healthy control participants included 80 194 coordinates from 9035 experiments. Model verification in healthy control data resulted in excellent model fit (root mean square error of approximation, 0.037; 90% CI: 0.036, 0.039). Twenty participants (mean age, 36 years ± 9 [standard deviation]; 12 women) with relapsing-remitting MS were evaluated. Model validation in resting-state functional MRI in participants with MS resulted in deviation from optimal model fit (root mean square error of approximation, 0.071; 90% CI: 0.070, 0.072), which correlated with EDSS scores (r = 0.68; P = .002). Conclusion The atrophy-based functional network model predicts functional network disruption in multiple sclerosis (MS), thereby supporting the network degeneration hypothesis. On resting-state functional MRI scans, reduced functional network integrity in participants with MS had a strong positive correlation with clinical disability. © RSNA, 2021 Online supplemental material is available for this article.

Creutzfeldt-Jakob Disease: In-hospital demographics report of national data in the United States from 2016 and review of a rapidly-progressive case.

BACKGROUND: This report highlights a rapidly progressive case of Creutzfeldt-Jakob Disease (CJD) whose time from symptom onset to death spanned less than two months. We also explore the most recently available in-patient demographics data for discharges with CJD in the United States. METHODS: We reviewed a CJD case and systematically analyzed a retrospective cohort of CJD discharges using the Healthcare Cost and Utilization Project (HCUP) to evaluate the existing national data on the status of CJD demographics and dispositions in the United States in 2016. RESULTS: An estimated total of 710 hospital discharges with a diagnosis of CJD were seen across the United States in 2016. According to HCUP, the average age of patients was 66.15 ±â€¯11.54 years with 48.6 % female. Average time to intubation from admission to hospital was 4.71 ±â€¯7.32 days with a rate of intubation of 6.34 %. The mean hospital cost was $19,901.25 ± $18,743.48. The rate of in-hospital mortality was 8.45 %. No significant geographical differences were noted (p = 0.49). No significant differences were seen among incidence in specific ethnic groups (p = 0.33) or income quartiles (p = 0.90). CONCLUSIONS: Our data shows that the incidence of CJD in 2016 appears to be equally distributed among individuals in the United States by demographic categories. Additionally, our case-study from 2019 illustrates an important example for diagnosing a rapidly-progressing case of CJD.

Characterization of normal-appearing white matter in multiple sclerosis using quantitative susceptibility mapping in conjunction with diffusion tensor imaging.

PURPOSE: Quantitative susceptibility mapping (QSM) is influenced by iron as well as myelin, which makes interpretation of pathologic changes challenging. Concurrent acquisition of MR sequences that are sensitive to axonal/myelin integrity, such as diffusion tensor imaging (DTI), may provide context for interpreting quantitative susceptibility (QS) signal. The purpose of our study was to investigate alterations in normal-appearing white matter (NAWM) in multiple sclerosis (MS) using QSM in conjunction with DTI. METHODS: Twenty relapsing-remitting MS patients and 20 age-matched healthy controls (HC) were recruited for this prospective study. QS, radial diffusivity (RD), fractional anisotropy (FA), and R2* maps within the whole brain as well as individual tracts were generated for comparison between NAWM and HC white matter (HCWM). RESULTS: MS lesions demonstrated significant differences in QS, FA, RD, and R2* compared to HCWM (p < 0.03). These metrics did not show a significant difference between whole-brain NAWM and HCWM. Among NAWM tracts, the cingulate gyri demonstrated significantly decreased QS compared to HCWM (p = 0.004). The forceps major showed significant differences in FA and RD without corresponding changes in QS (p < 0.01). CONCLUSION: We found discordant changes in QSM and DTI metrics within the cingulate gyri and forceps major. This may potentially reflect the influence of paramagnetic substrates such as iron, which could be decreased along these NAWM tracts. Our results point to the potential role of QSM as a unique biomarker, although additional validation studies are needed.

Anti-Hu-Associated Autoimmune Limbic Encephalitis in a Patient with PD-1 Inhibitor-Responsive Myxoid Chondrosarcoma.

Autoimmune encephalitis is an uncommon complication of immune checkpoint inhibitor therapy. This article reports a case of fatal anti-Hu-associated autoimmune limbic encephalitis presenting within 8 weeks following anti-PD1 therapy in a patient with myxoid chondrosarcoma and pre-existing anti-Hu antibodies. Although tumor reduction occurred in response to PD-1 inhibitor therapy, the patient had a rapidly progressive decline in neurologic function despite initial stabilization with immunosuppression. Considering the increasing use of immune checkpoint inhibitors for the treatment of various malignancies, an increase in the occurrence of neurologic adverse events is likely, requiring prompt intervention and enhanced pharmacovigilance in malignancies associated with onconeuronal antibodies.

Role of the Suprachiasmatic and Arcuate Nuclei in Diurnal Temperature Regulation in the Rat.

In mammals, daily changes in body temperature (Tb) depend on the integrity of the suprachiasmatic nucleus (SCN). Fasting influences the Tb in the resting period and the presence of the SCN is essential for this process. However, the origin of this circadian/metabolic influence is unknown. We hypothesized that, not only the SCN but also the arcuate nucleus (ARC), are involved in the Tb setting through afferents to the thermoregulatory median preoptic nucleus (MnPO). Therefore, we investigated by neuronal tracing and microdialysis experiments the possible targeting of the MnPO by the SCN and the ARC in male Wistar rats. We observed that vasopressin release from the SCN decreases the temperature just before light onset, whereas α-melanocyte stimulating hormone release, especially at the end of the dark period, maintains high temperature. Both peptides have opposite effects on the brown adipose tissue activity through thermoregulatory nuclei such as the dorsomedial nucleus of the hypothalamus and the dorsal raphe nucleus. The present study indicates that the coordination between circadian and metabolic signaling within the hypothalamus is essential for an adequate temperature control. SIGNIFICANCE STATEMENT: When circadian and metabolic systems are not well synchronized, individuals may develop metabolic diseases. The underlying mechanisms are unknown. Here, we demonstrate that the balance between the releases of neuropeptides derived from the biological clock and from a metabolic sensory organ as the arcuate nucleus, are essential for an adequate temperature control. These observations show that brain areas involved in circadian and metabolic functions of the body need to interact to produce a coherent arrangement of physiological processes associated with temperature control.

Organic light emitting diode improves diabetic cutaneous wound healing in rats.

A major complication for diabetic patients is chronic wounds due to impaired wound healing. It is well documented that visible red wavelengths can accelerate wound healing in diabetic animal models and patients. In vitro and in vivo diabetic models were used to investigate the effects of organic light emitting diode (OLED) irradiation on cellular function and cutaneous wound healing. Human dermal fibroblasts were cultured in hyperglycemic medium (glucose concentration 180 mM) and irradiated with an OLED (623 nm wavelength peak, range from 560 to 770 nm, power density 7 or 10 mW/cm2 at 0.2, 1, or 5 J/cm2). The OLED significantly increased total adenosine triphosphate concentration, metabolic activity, and cell proliferation compared with untreated controls in most parameters tested. For the in vivo experiment, OLED and laser (635 ± 5 nm wavelength) treatments (10 mW/cm2 , 5 J/cm2 daily for a total of seven consecutive days) for cutaneous wound healing were compared using a genetic, diabetic rat model. Both treatments had significantly higher percentage of wound closure on day 6 postinjury and higher total histological scores on day 13 postinjury compared with control. No statistical difference was found between the two treatments. OLED irradiation significantly increased fibroblast growth factor-2 expression at 36-hour postinjury and enhanced macrophage activation during initial stages of wound healing. In conclusion, the OLED and laser had comparative effects on enhancing diabetic wound healing.

A method for estimating and removing streaking artifacts in quantitative susceptibility mapping.

Quantitative susceptibility mapping (QSM) is a novel MRI method for quantifying tissue magnetic property. In the brain, it reflects the molecular composition and microstructure of the local tissue. However, susceptibility maps reconstructed from single-orientation data still suffer from streaking artifacts which obscure structural details and small lesions. We propose and have developed a general method for estimating streaking artifacts and subtracting them from susceptibility maps. Specifically, this method uses a sparse linear equation and least-squares (LSQR)-algorithm-based method to derive an initial estimation of magnetic susceptibility, a fast quantitative susceptibility mapping method to estimate the susceptibility boundaries, and an iterative approach to estimate the susceptibility artifact from ill-conditioned k-space regions only. With a fixed set of parameters for the initial susceptibility estimation and subsequent streaking artifact estimation and removal, the method provides an unbiased estimate of tissue susceptibility with negligible streaking artifacts, as compared to multi-orientation QSM reconstruction. This method allows for improved delineation of white matter lesions in patients with multiple sclerosis and small structures of the human brain with excellent anatomical details. The proposed methodology can be extended to other existing QSM algorithms.

Optical coherence tomography in Susac's syndrome.

Susac's syndrome is an autoimmune endotheliopathy with predilection for brain, retina and cochlea (Susac, 1994). Optical coherence tomography (OCT) is a non-invasive method, which is increasingly used in the diagnosis of retinal as well as primary central nervous system diseases. OCT is suggested as a useful diagnostic tool in differentiating Susac's syndrome from multiple sclerosis (MS) (Brandt et al., 2012). This report demonstrates the OCT findings in 3 patients with Susac's syndrome in different stages of the disease. The OCT demonstrated decreased retinal nerve fiber layer (RNFL) thickness, which was patchy in nature and more prominent in the nasal quadrants. We also observed loss of the normal foveal contour, which is uncharacteristic for MS. The extent and degree of the OCT abnormalities in our patients correlated with the stage and severity of the disease and correlated with the findings on the visual field studies. We confirm that OCT is a useful diagnostic tool in Susac's syndrome and helps to differentiate it from MS. Furthermore, OCT may be a non-invasive alternative to fluorescein angiography in longitudinal follow up of these patients.

Electrophoretic mobility of duplex DNA cross-linked by mechlorethamine at a cytosine-cytosine mismatch pair.

The common nitrogen mustard, mechlorethamine, can form a covalent cross-link between the two bases of a cytosine-cytosine mismatch pair within a DNA duplex. The cross-linked species can be readily separated from DNA monoadducts and unreacted strands using denaturing polyacrylamide gel electrophoresis. Here, using DNA 19 mer duplexes that are mechlorethamine cross-linked at a C(4)-C(35), C(7)-C(32), C(10)-C(29), or C(13)-C(26) mismatch pair, we show that the denaturing polyacrylamide gel electrophoresis mobility of the cross-linked species is particularly sensitive to the proximity of the C-C cross-link to the duplex end. Species that are cross-linked at a C(4)-C(35) mismatch have greater mobilities than those cross-linked at C(7)-C(32) or C(13)-C(26), and the species with a central C(10)-C(29) cross-link have the lowest mobility. The mobility is also dependent on the proximity of the cross-link to a 5'-(32)P-phosphate or a 5'-fluorescein label. We interpret these results in terms of the conformational properties of the cross-linked species in the denaturing gel. The results are consistent with the retention of partial duplex character at the end proximal to the cross-link, with an influence on the mobility of the GC/AT ratio proximal to the cross-link and at the duplex end, and a small but discernible effect of the label.

Homonymous hemimacular thinning: a unique presentation of optic tract injury in neuromyelitis optica.

A 42-year-old African American woman with a 5-year history of neuromyelitis optica was found to have an incongruous homonymous hemianopia. Optical coherence tomography (OCT) showed corresponding left homonymous hemimacular thinning. Magnetic resonance imaging of the brain demonstrated a demyelinating lesion in the left optic tract (OT) just anterior to the lateral geniculate nucleus and diffusion tensor magnetic resonance tractography confirmed axonal fiber loss in the left OT. This case illustrates the complementary and confirmatory roles of visual field testing, macular OCT, and neuroimaging in an OT lesion, which caused selective hemimacular thinning through retrograde degeneration.

Information intervention in the pharmaceutical sciences.

Professional guidelines state that higher-order thinking skills are a desirable outcome of pharmacy education. In this context, courses in pharmaceutics at the University of Southern California are taught in a learner-centered manner that requires use of chemical reference sources and interpretation of physicochemical information for drug molecules. To facilitate these activities, a librarian worked with faculty to design a class on reference sources and primary literature. Students believed the librarian instruction was beneficial. After the intervention, faculty fielded fewer information-related questions and the librarian received more sophisticated questions. The class emphasizes the importance of collaboration between librarians and faculty in achieving these results.

HPLC-UV, MALDI-TOF-MS and ESI-MS/MS analysis of the mechlorethamine DNA crosslink at a cytosine-cytosine mismatch pair.

BACKGROUND: Mechlorethamine [ClCH(2)CH(2)N(CH(3))CH(2)CH(2)Cl], a nitrogen mustard alkylating agent, has been proven to form a DNA interstrand crosslink at a cytosine-cytosine (C-C) mismatch pair using gel electrophoresis. However, the atomic connectivity of this unusual crosslink is unknown. METHODOLOGY/PRINCIPAL FINDINGS: HPLC-UV, MALDI-TOF-MS, and ESI-MS/MS were used to determine the atomic connectivity of the DNA C-C crosslink formed by mechlorethamine, MALDI-TOF-MS of the HPLC-purified reaction product of mechlorethamine with the DNA duplex d[CTCACACCGTGGTTC]•d[GAACCACCGTGTGAG] (underlined bases are a C-C mismatch pair) indicated formation of an interstrand crosslink at m/z 9222.088 [M-2H+Na](+). Following enzymatic digestion of the crosslinked duplex by snake venom phosphodiesterase and calf intestinal phosphatase, ESI-MS/MS indicated the presence of dC-mech-dC [mech = CH(2)CH(2)N(CH(3))CH(2)CH(2)] at m/z 269.2 [M](2+) (expected m/z 269.6, exact mass 539.27) and its hydrolytic product dC-mech-OH at m/z 329.6 [M](+) (expected m/z 329.2). Fragmentation of dC-mech-dC gave product ions at m/z 294.3 and 236.9 [M](+), which are both due to loss of the 4-amino group of cytosine (as ammonia), in addition to dC and dC+HN(CH(3))CH = CH(2), respectively. The presence of m/z 269.2 [M](2+) and loss of ammonia exclude crosslink formation at cytosine N(4) or O(2) and indicate crosslinking through cytosine N(3) with formation of two quaternary ammonium ions. CONCLUSIONS: Our results provide an important addition to the literature, as the first example of the use of HPLC and MS for analysis of a DNA adduct at the N(3) position of cytosine.

Quantitative assessment of assisted problem-based learning in a pharmaceutics course.

OBJECTIVES: To assess the effectiveness of assisted problem-based learning (PBL) compared to a didactic approach in a pharmaceutics course. DESIGN: Data were collected over 7 offerings of the course. In the first half of the semester about half of the students (PBL1) learned in a PBL format while the other students (PBL2) received didactic lectures. In the second half of the semester, the teaching methods were reversed. ASSESSMENT: Performance on the midterm examination and a comprehensive final examination was used to assess the effect of PBL. Over the 7-year period, PBL1 students scored significantly higher on the midterm examinations. Scores on the final examinations did not differ significantly, but PBL2 students had a higher mean score on questions based on material from the second half of the semester. CONCLUSIONS: PBL produced a short-term (weeks) improvement in learning and our results suggest that the effect may persist in the medium term (months).