Behavior of the dengue virus in solution

The dengue virus consists of four antigenically related but distinct viruses, termed Dengue virus 1-4 (DEN 1-4). We have established that the dengue virus loses infectivity over time in solution in an exponentially declining manner. The four strains examined (one from each serotype) have half-lives that range from 2.5 to 7.5 hr in defined medium. The half-life is temperature and pH-dependent and is affected by the nature of the host cell in which it is produced, but is not dependent upon the presence of either Mg(2+) ions or chelating agents. Electron microscopy (EM) of solutions of the dengue virus show almost complete virus aggregation after 24 hr at room temperature, while RT-PCR shows an intact RNA genome. These results show that the solution environment of the dengue virus is an important determinant of dengue virus infectivity.     

Pharmacokinetics and pharmacodynamics profiles of enteric‐coated mycophenolate sodium in female patients with difficult‐to‐treat lupus nephritis

Relapsed or resistant lupus nephritis (LN) is considered a difficult‐to‐treat type of LN, and enteric‐coated mycophenolate sodium (EC‐MPS) has been used in this condition. Therapeutic drug monitoring using the area under the plasma mycophenolic acid concentration from 0 to 12 h postdose (MPA‐AUC_0–12h) ≥45 μg.h/ml is a useful approach to achieve the highest efficiency. This study assessed EC‐MPS’s pharmacokinetic (PK) and pharmacodynamic (PD) profiles and investigated an optimal level of the single time point of plasma MPA concentration. Nineteen biopsy‐proven patients with class III/IV LN received 1440 mg/day of EC‐MPS for 24 weeks. PK (maximum plasma MPA concentration [C _max], time to C _max, and MPA‐AUC_0–12h) and PD (activity of inosine‐5′‐monophosphate dehydrogenase [IMPDH]) parameters were measured at weeks 2, 8, 16, and 24. We found that IMPDH activity decreased from baseline by 31–42% within 2–4 h after dosing, coinciding with the increased plasma MPA concentration. MPA‐AUC_0–12h ≥45 μg.h/ml was best predicted by a single time point MPA concentration at C0.5, C2, C3, C4, and C8 (r ² = 0.516, 0.514, 0.540, 0.611, and 0.719, respectively), independent of dose, albumin, urine protein/creatinine ratio, and urinalysis. The MPA‐C0.5 cutoff of 2.03 g/ml yielded the highest overall sensitivity of 85% and specificity of 88.2% in predicting MPA‐AUC_0–12h ≥45 μg.h/ml. A single timepoint of plasma MPA‐C0.5 ≥2.03 μg/ml may help guide EC‐MPS adjustment to achieve adequate drug exposure. Further study of EC‐MPS used to validate this cutoff is warranted.

Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? Therapeutic drug monitoring (TDM) is crucial in lupus nephritis (LN) treated with mycophenolic acid (MPA), especially mycophenolate mofetil. The area under the plasma concentration‐time curve of MPA from time 0 to 12 h (MPA‐AUC_0–12h) ≥ 45 μg.h/ml or a single plasma MPA concentration (C0 or C1) are used as tools to enhance the highest treatment efficacy. In addition, enteric‐coated mycophenolate sodium (EC‐MPS) was also used to treat relapsed or resistant LN. However, little is known regarding the TDM of EC‐MPS. WHAT QUESTION DID THIS STUDY ADDRESS? This study assessed EC‐MPS’s pharmacokinetics (PKs) and pharmacodynamics (PDs) in adult patients with relapsed or resistant LN and investigated a surrogate single timepoint of plasma MPA concentration with optimum plasma level cutoff as an alternative for MPA‐AUC. WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? This study provided EC‐MPS’s PK and PD profiles and suggested a surrogate single timepoint of plasma MPA concentration with optimum plasma level cutoff as potential alternatives for MPA‐AUC_0–12 ≥45 μg.h/ml to be applied in TDM. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? This study supports the role of TDM in relapsed or resistant LN treated with EC‐MPS. In addition, a single timepoint of plasma MPA concentration at C0.5 with the proposed cutoff at ≥2.03 μg/ml is a TDM tool that can be easily applied in clinical practice. However, a more significant number of study patients is required.     

Involvement of ATP synthase β subunit in chikungunya virus entry into insect cells

Chikungunya virus (CHIKV), the virus responsible for the disease chikungunya fever in humans, is transmitted by Aedes mosquitoes. While significant progress has been made in understanding the process by which CHIKV enters into mammalian cells, far less progress has been made in understanding the CHIKV entry process in insect cells. This study sought to identify mosquito-cell-expressed CHIKV-binding proteins through a combination of virus overlay protein binding assays (VOPBA) and mass spectroscopy. A 50-kDa CHIKV-binding protein was identified as the ATP synthase β subunit (ATPSβ). Co-immunoprecipitation studies confirmed the interaction, and colocalization analysis showed cell-surface and intracellular co-localization between CHIKV and ATPSβ. Both antibody inhibition and siRNA-mediated downregulation experiments targeted to ATPSβ showed a significant reduction in viral entry and virus production. These results suggest that ATPSβ is a CHIKV-binding protein capable of mediating the entry of CHIKV into insect cells.     

A Small-Plaque Isolate of the Zika Virus with Envelope Domain III Mutations Affect Viral Entry and Replication in Mammalian but Not Mosquito Cells

An Asian Zika virus (ZIKV) isolated from a Thai patient that was serially passaged in Primary Dog Kidney (PDK) cells for attenuation displayed both big and small plaque-forming viruses by the 7th passage. Two small-plaque isolates were selected and purified for characterization as attenuated ZIKV candidates. In vitro growth kinetics showed significantly reduced titers for small-plaque isolates in Vero cells early post-infection compared to the parental ZIKV and a big-plaque isolate, but no significant difference was observed in C6/36 cells. Viral entry experiments elucidate that titer reduction likely occurred due to the diminished entry capabilities of a small-plaque isolate. Additionally, a small-plaque isolate displayed lowered neurovirulence in newborn mice compared to 100% lethality from infection with the parental ZIKV. Genomic analysis revealed the same three unique non-synonymous mutations for both small-plaque isolates: two on the envelope (E) protein at residues 310, alanine to glutamic acid (A310E), and 393, glutamic acid to lysine (E393K), and one on residue 355 of NS3, histidine to tyrosine (H355Y). Three-dimensional (3D) mapping suggests that the E protein mutations located on the receptor-binding and fusion domain III likely affect cell entry, tropism, and virulence. These ZIKV isolates and genotypic markers will be beneficial for vaccine development.     

Characterization of putative Japanese encephalitis virus receptor molecules on microglial cells

Japanese encephalitis virus (JEV) a mosquito-borne flavivirus is a major cause of viral encephalitis in Asia. While the principle target cells for JEV in the central nervous system are believed to be neurons, microglia are activated in response to JEV and have been proposed to act as a long lasting virus reservoir. Viral attachment to a host cell is the first step of the viral entry process and is a critical mediator of tissue tropism. This study sought to identify molecules associated with JEV entry to microglial cells. Virus overlay protein-binding assay (VOPBA) and liquid chromatography-mass spectrometry (LC/MS/MS) identified the 37/67 kDa high-affinity laminin receptor protein and nucleolin as a potential JEV-binding proteins. These proteins were subsequently investigated for a contribution to JEV entry to mouse microglial BV-2 cells together with other possible candidate receptor molecules including Hsp70, Hsp90, GRP78, CD14, and CD4. In antibody mediated inhibition of infection experiments, both anti-laminin receptor and anti-CD4 antibodies significantly reduced virus entry while anti-Hsp70 and 90 antibodies produced a slight reduction. Significant inhibition of virus entry (up to 80%) was observed in the presence of lipopolysaccharide (LPS) which resulted in a complete down-regulation of CD4 and moderate down-regulation of CD14. These results suggest that multiple receptor proteins may mediate the entry of JEV to microglial cells, with CD4 playing a major role.     

Alteration of noncollagenous bone matrix proteins in distal renal tubular acidosis

Our previous report on bone histomorphometry in patients with distal renal tubular acidosis (dRTA) revealed decreased bone formation rate (BFR) when compared to healthy subjects. The abnormality improved significantly after alkaline therapy. The modest increase in osteoblastic surface, after correction of metabolic acidosis, could not explain the striking improvement in bone formation, suggesting additional influence of metabolic acidosis on osteoblast function and/or bone matrix mineralization. Osteoblasts and, to a lesser extent, osteoclasts synthesize and secrete bone matrix including type I collagen and various noncollagenous proteins (NCPs). Substantial evidence suggested diverse functions of NCPs related to bone formation, resorption, and mineralization. Metabolic acidosis, through its effect on bone cells, may result in an alteration in the production of NCPs. Our study examined bone histomorphometry with detailed analysis on the mineralization parameters and NCPs expression within the bone matrix of patients with dRTA before and after treatment with alkaline. Seven dRTA patients underwent bone biopsy at their initial diagnosis and again 12 months after alkaline therapy. Bone mineral density (BMD) and bone histomorphometry were obtained at baseline and after the treatment. The expression of NCPs was examined by immunohistochemistry, quantitated by digital image analysis, and reported as a percentage of area of positive staining or mineralized trabecular bone area. Alkaline therapy normalized the low serum phosphate and PTH during acidosis. The reduction in BMD at baseline improved significantly by the treatment. Bone histomorphometry demonstrated the increase in osteoid surface and volume without significant alteration after acidosis correction. In comparison to the normal subjects, osteoid thickness was slightly but insignificantly elevated. Osteoblast and osteoclast populations and their activities were suppressed. The reduction in mineral apposition rate and adjusted apposition rate were observed in conjunction with the prolongation of mineralization lag time. Alkaline therapy improved the mineralization parameters considerably. In addition to the increase in BFR relative osteoblast number after acidosis correction, osteocalcin expression in the bone matrix increased significantly from 16.7% to 22.3%. Six of seven patients had decreased osteopontin expression. In conclusion, the abnormal bone remodeling in dRTA is characterized by low turnover bone disease with some degree of defective mineralization. Alteration of NCPs expression suggested the effect of metabolic acidosis on bone cells. Alkaline therapy increased bone mass through the restoration of bone mineral balance and, perhaps, improved osteoblast function.     

Behavior Problems and Cognitive Function in Pediatric Liver Transplant Recipients

BackgroundLiver transplant (LT) is a lifesaving treatment providing excellent clinical outcomes. However, data regarding behavioral and cognitive issues after LT are sparse in Asia. This study aimed to investigate behavior and cognitive problems among pediatric LT recipients.MethodsWe used the Child Behavior Checklist (CBCL) to evaluate behavior problems and/or the Wechsler Intelligence Scale for Children, Third Edition (WISC-III) to assess cognitive function. Participants were children aged 2 to 18 years who were treated with LT for at least 2 years.ResultsWe included 77 children with a median age of 7.8 years (interquartile range, 5.0-10.9). All children were evaluated with the CBCL, and 26 children were available for WISC-III assessment. Approximately one-third (34%) of the children had a total CBCL score above a clinical cutoff for significant behavior problems, and 29% of school-aged children had abnormal competence scores in a clinically significant range. Most of the evaluated children (17 of 26; 65%) had a normal full-scale intelligence quotient. Lower cognitive function was associated with having a single parent (P < .01). Higher behavior problems were associated with lower parental education level (P = .01) and correlated with longer post-transplant duration (Spearman’s rho = 0.443; P < .001).ConclusionsSignificant numbers of children have behavior problems after LT. Most children have normal cognitive function, although a larger sample size is required to confirm this result. Long-term support for cognitive and behavior problems after LT should be implemented, particularly in children with single parents and lower parental education level.     

Effects of intradialytic cycling exercise on daily physical activity,physical fitness,body composition,and clinical parameters in high-volume online hemodiafiltration patients: a pilot randomized-controlled trial

Purpose

The mortality of dialysis patients treated with high-volume online hemodiafiltration (OL-HDF) is better than hemodialysis, but is still higher than healthy population. Low daily physical activity increases cardiovascular mortality. Addition of intradialytic exercise (IDX) program might improve physical activity and health status in OL-HDF patients. This pilot open-labeled randomized-controlled trial was conducted to evaluate the effects of IDX on physical activity and other clinical parameters in OL-HDF patients.

Methods

Twelve OL-HDF patients were randomized into control (n?=?6) or IDX (n?=?6) groups. The subjects in IDX group were trained to exercise using a cycle ergometer for 60 min during each OL-HDF session. Physical activity measured as daily step count using a wrist-worn triaxial accelerometer, physical fitness, or cardiorespiratory fitness assessed by VO₂max and other physical performance tests, lean body mass determined by the Dual-energy X-ray absorptiometry (DXA), quality of life (QOL), and various parameters were compared between baseline and 6 months.

Results

The baseline physical activity status was comparable. Following 6-month IDX, the physical activity was significantly improved in IDX group [+?1048.79 (+?741.50,?+?2792.54) vs. ? 362.06 (? 1626.82, ? 167.47) steps/day, p?=?0.01], while physical fitness and QOL were unchanged. The lean body mass parameters were preserved in the IDX group while seemed to decrease in the control group. Serum albumin was significantly increased in the IDX group (p?=?0.01). The hemoglobin changes were significantly better (p?=?0.01) and the erythropoietin resistance index was significantly lower in the IDX group (p?=?0.03). Phosphate reduction was significantly greater in the IDX group (p?=?0.04).

Conclusions

IDX could improve physical activity and other metabolic parameters in OL-HDF patients and these might contribute to further improvement in clinical and survival outcomes.

Trial registration

ClinicalTrials.gov Registration: NCT03353844.

     

Fibromuscular dysplasia: a rare cause of cilioretinal artery occlusion in childhood

OBJECTIVE: To report a case of cilioretinal artery occlusion with angiographic findings characteristic of the "string of beads" associated with renovascular hypertension secondary to fibromuscular dysplasia of the renal artery in a child. DESIGN: Case report. INTERVENTION: The patient underwent ex vivo renal artery reconstruction with saphenous vein graft and reimplantation. MAIN OUTCOME MEASURES: The main clinical outcomes were control of severe hypertension, reversible hypertensive retinopathy, and improvement of vision. RESULTS: Revascularization of the kidney improved renal function, and renovascular hypertension was clearly improved. Visual acuity improved to 20/200. CONCLUSIONS: A child with hypertensive retinopathy and arterial occlusion in the retina should undergo investigation to rule out a surgically curable hypertension. Magnetic resonance angiography of extrarenal vessels may reveal other sites of involvement of fibromuscular dysplasia. Evaluation and early diagnosis of renovascular hypertension will prevent severe end-organ damage.