Safety of Direct‐Acting Antiviral Therapy for Renal Function in Post‐Kidney Transplant Patients Infected with Hepatitis C Virus and a 100% 12‐Week Sustained Virologic Response: A Single‐Center Study

Treatment of chronic hepatitis C infection after renal transplantation has been controversial due to the high rate of graft rejections with interferon (IFN)‐based therapies. The aim of this study is to review our experience of direct acting antiviral therapy for the recipients of renal transplantation. Eleven recipients who were hepatitis C virus‐polymerase chain reaction (PCR) positive were eligible for the treatment with direct acting antivirals. Six recipients were treated with sofosbuvir and ledipasvir, three were treated with elbasvir and grazoprevir, and one was treated with sofosbuvir and ribavirin for 12 weeks. One recipient was treated with glecaprevir and pibrentasvir for 8 weeks. All of the 11 recipients exhibited sustained virologic response at week 12 after the end of treatment. Adverse events were scarce including the two recipients who switched to tacrolimus from cyclosporine at the beginning of the treatment. The direct acting antiviral therapy including new agents appears to be safe and highly efficacious for the recipients after renal transplantation.     

Intermittent Oral Dosing of Roxadustat in Peritoneal Dialysis Chronic Kidney Disease Patients with Anemia: A Randomized,Phase 3, Multicenter,Open‐Label Study

Roxadustat is an oral hypoxia‐inducible factor prolyl hydroxylase inhibitor developed to treat anemia in chronic kidney disease (CKD) patients. This Phase 3, randomized, open‐label, 24‐week study investigated the efficacy and safety of roxadustat in Japanese CKD patients with anemia on peritoneal dialysis (PD) who were previously treated or not treated with erythropoiesis stimulating agents (ESAs). Patients not previously receiving ESA (ESA‐Naïve group) were randomized to roxadustat at a starting dose of 50 or 70 mg three times weekly; patients previously receiving ESA (ESA‐Converted group) switched from ESA to roxadustat 70 or 100 mg three times weekly depending on the prior ESA dose. Outcomes included maintenance rate of average hemoglobin (Hb) level within 10–12 g/dL at weeks 18–24, cumulative response rate at end of treatment (Hb thresholds, 10.0 g/dL or 10.5 g/dL; Hb increase, ≥1.0 g/dL), and average Hb levels at weeks 18–24. Safety was assessed by occurrence of treatment‐emergent adverse events (TEAEs). Fifty‐six patients were enrolled (ESA‐Naïve, n = 13; ESA‐Converted, n = 43). Maintenance rates (weeks 18–24) were 92.3% (95% CI: 64.0–99.8; ESA‐Naïve) and 74.4% (95% CI: 58.8–86.5; ESA‐Converted). Cumulative response rate was 100.0% in the ESA‐Naïve group. Average Hb levels (weeks 18–24) were 11.05 g/dL (95% CI: 10.67–11.42; ESA‐Naïve) and 10.93 g/dL (95% CI: 10.73–11.13; ESA‐Converted). Common TEAEs included nasopharyngitis and back pain. Roxadustat was well tolerated and effective in maintaining target Hb levels in CKD patients on PD who were previously treated or not treated with ESA.     

Neurotrophin production in brain pericytes during hypoxia: a role of pericytes for neuroprotection

Neurotrophins are crucial regulators of neuronal survival and death. Evidence suggests that cells comprising the neurovascular unit (NVU) cooperatively mediate neuronal development, survival and regeneration. The aim of this study was to test whether cerebrovascular cells, endothelial cells and pericytes, produce neurotrophins and play neuroprotective roles during hypoxic insults. We examined the expression of neurotrophins and their receptors in cultured human cerebral microvascular endothelial cells and pericytes, astrocytes and the rat neuronal cell line PC12. Differentiated PC12 cells expressed TrkA, the NGF receptor, which was significantly upregulated by hypoxia at 1% O(2) and regulated neuronal survival. Both pericytes and astrocytes expressed three neurotrophins, i.e. NGF, BDNF and NT-3, while TrkB and TrkC, specific receptors for BDNF and NT-3, were expressed in astrocytes, but not pericytes. In response to hypoxia, among the neurotrophins expressed in pericytes and astrocytes only NT-3 expression was significantly upregulated in pericytes. Treatment of astrocytes with NT-3 significantly activated Erk1/2 and increased the expression of NGF both at mRNA and protein levels. The MEK1 inhibitor U0126 or siRNA-mediated knockdown of TrkC abolished the NT-3-induced upregulation of NGF in astrocytes. Taken together, cerebral microvascular pericytes and astrocytes are potent producers of neurotrophins in the NVU. In response to hypoxia, pericytes increase NT-3 production, which induces astrocytes to increase NGF production through the TrkC-Erk1/2 pathway. The interplay between pericytes and astrocytes through neurotrophins in the NVU may play an important role in neuronal survival under hypoxic conditions.     

Keap1 degradation by autophagy for the maintenance of redox homeostasis

The Kelch-like ECH-associated protein 1 (Keap1)-NF-E2-related factor 2 (Nrf2) system is essential for cytoprotection against oxidative and electrophilic insults. Under unstressed conditions, Keap1 serves as an adaptor for ubiquitin E3 ligase and promotes proteasomal degradation of Nrf2, but Nrf2 is stabilized when Keap1 is inactivated under oxidative/electrophilic stress conditions. Autophagy-deficient mice show aberrant accumulation of p62, a multifunctional scaffold protein, and develop severe liver damage. The p62 accumulation disrupts the Keap1-Nrf2 association and provokes Nrf2 stabilization and accumulation. However, individual contributions of p62 and Nrf2 to the autophagy-deficiency-driven liver pathogenesis have not been clarified. To examine whether Nrf2 caused the liver injury independent of p62, we crossed liver-specific Atg7::Keap1-Alb double-mutant mice into p62- and Nrf2-null backgrounds. Although Atg7::Keap1-Alb::p62(-/-) triple-mutant mice displayed defective autophagy accompanied by the robust accumulation of Nrf2 and severe liver injury, Atg7::Keap1-Alb::Nrf2(-/-) triple-mutant mice did not show any signs of such hepatocellular damage. Importantly, in this study we noticed that Keap1 accumulated in the Atg7- or p62-deficient mouse livers and the Keap1 level did not change by a proteasome inhibitor, indicating that the Keap1 protein is constitutively degraded through the autophagy pathway. This finding is in clear contrast to the Nrf2 degradation through the proteasome pathway. We also found that treatment of cells with tert-butylhydroquinone accelerated the Keap1 degradation. These results thus indicate that Nrf2 accumulation is the dominant cause to provoke the liver damage in the autophagy-deficient mice. The autophagy pathway maintains the integrity of the Keap1-Nrf2 system for the normal liver function by governing the Keap1 turnover.     

Bone temperature elevation by drilling friction and neurological outcome in the cervical spino-laminoplasty

Background

Drill-induced heat has been suspected as a cause of tissue injury, and there are ample experimental data to substantiate the implication. However, no clinical results have been presented with measurement of temperature in the vicinity of neural structures during the actual spinal procedures.

Methods

Using a thermocouple, temperature in the gutters drilled in the midline and the lateral margins of the lamina was monitored closely in 61 patients, who underwent the French-door style of cervical spino-laminoplasty. The drilling was performed intermittently for a duration of 5 or 10 seconds, using 3- or 5-mm diamond burrs with sufficient continuous cooling irrigation. The correlations between bone temperature elevation and postoperative sensorimotor symptoms were then analyzed.

Results

In the lateral gutters at the most cephalad level (typically C3), where the drilling was performed underneath an overlying bundle of muscle attached to C2's spinous process, the temperature rose significantly. This occurred even with 5-second drilling sessions. The average peak temperature was 44 °C at this level. At all other sites, the temperature was maintained below 40 °C. In three patients, transient neurological deficit developed postoperatively, which did not correlate with the incidence of bone temperature elevation.

Conclusions

Intermittent drilling with sufficient irrigation can prevent thermal neuronal damage generated by high-speed drills. Drilling with small diamond burrs in deep and narrow spaces covered by overlying muscles predisposes to inadequate irrigation and thermal elevation. Continuous, protracted drilling without frequent irrigation may result in excessive heat generation and nerve injury.