Going to war on COVID-19: Mobilizing an academic nephrology group practice.

AIM: The COVID-19 pandemic poses unprecedented operational challenges to nephrology divisions in every country as they cope with COVID-19-related kidney disease in addition to regular patient care. Although general approaches have been proposed, there is a lack of practical guidance for nephrology division response in a hospital facing a surge of cases. Here, we describe the specific measures that our division has taken in the hope that our experience in Singapore may be helpful to others. METHODS: Descriptive narrative. RESULTS: A compilation of operational responses to the COVID-19 pandemic taken by a nephrology division at a Singapore university hospital. CONCLUSION: Nephrology operational readiness for COVID-19 requires a clinical mindset shift from usual standard of care to a crisis exigency model that targets best outcomes for available resources. Rapid multi-disciplinary efforts that evolve flexibly with the local dynamics of the outbreak are required.

Pushing the limits of immune-related response: a case of "extreme pseudoprogression".

The advent of immune checkpoint targeted immunotherapy has seen a spectrum of immune-related phenomena in both tumor responses and toxicities. We describe a case of pseudoprogression that pushes the limits of immune-related response criteria and challenges the boundaries and definitions set by trial protocols. A middle-aged man with conventional clear cell renal cell carcinoma (RCC) had received multiple prior systemic treatments including vascular endothelial growth factor receptor tyrosine kinase inhibitors, as well as multiple surgeries and radiotherapy treatments. He was eventually started on nivolumab-the anti-programmed death receptor-1 monoclonal antibody approved for the treatment of advanced RCC. Clinical deterioration was observed soon after a 100 mg dose of nivolumab, with onset of acute renal failure and declining performance status. Radiologic progression was documented in multiple sites including worsening tumor infiltration of his residual kidney. The patient was on palliative treatment and visited by the home hospice team in an end-of-life situation. The patient unexpectedly improved and went on to achieve a durable tumor response. The case is illustrative of an extreme manifestation of pseudoprogression, and impels us to probe the assumptions and controversies surrounding this phenomenon.

Myths in peritoneal dialysis.

PURPOSE OF REVIEW: To clarify misconceptions about the feasibility and risks of peritoneal dialysis that unnecessarily limit peritoneal dialysis uptake or continuation in patients for whom peritoneal dialysis is the preferred dialysis modality. The inappropriate choice of haemodialysis as a result of these misconceptions contributes to low peritoneal dialysis penetrance, increases transfer from peritoneal dialysis to haemodialysis, increases expenditure on haemodialysis and compromises quality of life for these patients. RECENT FINDINGS: Peritoneal dialysis is an excellent renal replacement modality that is simple, cost-effective and provides comparable clinical outcomes to conventional in-centre haemodialysis. Unfortunately, many patients are deemed unsuitable to start or continue peritoneal dialysis because of false or inaccurate beliefs about peritoneal dialysis. Here, we examine some of these 'myths' and critically review the evidence for and against each of them. We review the feasibility and risk of peritoneal dialysis in patients with prior surgery, ostomies, obesity and mesh hernia repairs. We examine the fear of mediastinitis with peritoneal dialysis after coronary artery bypass graft surgery and the belief that the use of hypertonic glucose dialysate causes peritoneal membrane failure. SUMMARY: By clarifying common myths about peritoneal dialysis, we hope to reduce overly cautious practices surrounding this therapy.

Both the folate cycle and betaine-homocysteine methyltransferase contribute methyl groups for DNA methylation in mouse blastocysts.

The embryonic pattern of global DNA methylation is first established in the inner cell mass (ICM) of the mouse blastocyst. The methyl donor S-adenosylmethionine (SAM) is produced in most cells through the folate cycle, but only a few cell types generate SAM from betaine (N,N,N-trimethylglycine) via betaine-homocysteine methyltransferase (BHMT), which is expressed in the mouse ICM. Here, mean ICM cell numbers decreased from 18-19 in controls to 11-13 when the folate cycle was inhibited by the antifolate methotrexate and to 12-14 when BHMT expression was knocked down by antisense morpholinos. Inhibiting both pathways, however, much more severely affected ICM development (7-8 cells). Total SAM levels in mouse blastocysts decreased significantly only when both pathways were inhibited (from 3.1 to 1.6 pmol/100 blastocysts). DNA methylation, detected as 5-methylcytosine (5-MeC) immunofluorescence in isolated ICMs, was minimally affected by inhibition of either pathway alone but decreased by at least 45-55% when both BHMT and the folate cycle were inhibited simultaneously. Effects on cell numbers and 5-MeC levels in the ICM were completely rescued by methionine (immediate SAM precursor) or SAM. Both the folate cycle and betaine/BHMT appear to contribute to a methyl pool required for normal ICM development and establishing initial embryonic DNA methylation.

Betaine homocysteine methyltransferase is active in the mouse blastocyst and promotes inner cell mass development.

Methyltransferases are an important group of enzymes with diverse roles that include epigenetic gene regulation. The universal donor of methyl groups for methyltransferases is S-adenosylmethionine (AdoMet), which in most cells is synthesized using methyl groups carried by a derivative of folic acid. Another mechanism for AdoMet synthesis uses betaine as the methyl donor via the enzyme betaine-homocysteine methyltransferase (BHMT, EC 2.1.1.5), but it has been considered to be significant only in liver. Here, we show that mouse preimplantation embryos contain endogenous betaine; Bhmt mRNA is first expressed at the morula stage; BHMT is abundant at the blastocyst stage but not other preimplantation stages, and BHMT activity is similarly detectable in blastocyst homogenates but not those of two-cell or morula stage embryos. Knockdown of BHMT protein levels and reduction of enzyme activity using Bhmt-specific antisense morpholinos or a selective BHMT inhibitor resulted in decreased development of embryos to the blastocyst stage in vitro and a reduction in inner cell mass cell number in blastocysts. The detrimental effects of BHMT knockdown were fully rescued by the immediate methyl-carrying product of BHMT, methionine. A physiological role for betaine and BHMT in blastocyst viability was further indicated by increased fetal resorption following embryo transfer of BHMT knockdown blastocysts versus control. Thus, mouse blastocysts are unusual in being able to generate AdoMet not only by the ubiquitous folate-dependent mechanism but also from betaine metabolized by BHMT, likely a significant pool of methyl groups in blastocysts.

Peritoneal Dialysis-Related Peritonitis from Carbapenemase-Producing Klebsiella pneumoniae with OXA-48 Type Gene.

We report a rare case of carbapenemase-producing enterobacte-riaceae peritonitis in a patient undergoing automated peritoneal dialysis (APD). The PD catheter had to be removed as the patient remained unwell despite antibiotics. Antimicrobial resistance in PD peritonitis is a concern in this era of multi-drug resistant bacteria.

The DEAD-box protein DP103 (Ddx20 or Gemin-3) represses orphan nuclear receptor activity via SUMO modification.

Structural analysis of nuclear receptor subfamily V orphan nuclear receptors suggests that ligand-independent mechanisms must regulate this subclass of receptors. Here, we report that steroidogenic factor 1 (SF-1) and liver receptor homolog 1 are repressed via posttranslational SUMO modification at conserved lysines within the hinge domain. Indeed, mutating these lysines or adding the SUMO isopeptidase SENP1 dramatically increased both native and Gal4-chimera receptor activities. The mechanism by which SUMO conjugation attenuates SF-1 activity was found to be largely histone deacetylase independent and was unaffected by the AF2 corepressor Dax1. Instead, our data suggest that SUMO-mediated repression involves direct interaction of the DEAD-box protein DP103 with sumoylated SF-1. Of potential E3-SUMO ligase candidates, PIASy and PIASxalpha strongly promoted SF-1 sumoylation, and addition of DP103 enhanced both PIAS-dependent receptor sumoylation and SF-1 relocalization to discrete nuclear bodies. Taken together, we propose that DEAD-box RNA helicases are directly coupled to transcriptional repression by protein sumoylation.

Wanted DEAD/H or Alive: Helicases Winding Up in Cancers.

Cancer is one of the most studied areas of human biology over the past century. Despite having attracted much attention, hype, and investments, the search to find a cure for cancer remains an uphill battle. Recent discoveries that challenged the central dogma of molecular biology not only further increase the complexity but also demonstrate how various types of noncoding RNAs such as microRNA and long noncoding RNA, as well as their related processes such as RNA editing, are important in regulating gene expression. Parallel to this aspect, an increasing number of reports have focused on a family of proteins known as DEAD/H-box helicases involved in RNA metabolism, regulation of long and short noncoding RNAs, and novel roles as "editing helicases" and their association with cancers. This review summarizes recent findings on the roles of RNA helicases in various cancers, which are broadly classified into adult solid tumors, childhood solid tumors, leukemia, and cancer stem cells. The potential small molecule inhibitors of helicases and their therapeutic value are also discussed. In addition, analyzing next-generation sequencing data obtained from public portals and reviewing existing literature, we provide new insights on the potential of DEAD/H-box helicases to act as pharmacological drug targets in cancers.

Validation of (1)H NMR spectroscopy as an analytical tool for methylamine metabolites in urine.

BACKGROUND: Methylamines have many metabolic roles and there is an increasing demand for their measurement. Glycine betaine is an important osmolyte, and a reservoir for methyl groups. Proline betaine and trigonelline are important dietary betaines. Trimethylamine, derived from gut flora, is normally converted to trimethylamine oxide but in 'fish odour syndrome' is excreted as TMA. These compounds are all suitable for quantification by (1)H NMR spectroscopy as they all have methyl protons. METHOD: Urine samples are acidified and (1)H NMR spectra are obtained using presaturation for water suppression. Peak integrals or heights are compared to an internal standard of acetonitrile. RESULTS: Inter- and intra-assay CV's were <5% for TMAO and creatinine, and <10% for the other analytes. Responses were linear from 50 to 1000 microM for all metabolites, and recoveries were > or =97%. Limits of detection using NMR are slightly higher than alternative HPLC assays (15-25 microM). However, sensitivity is adequate for the detection of raised levels in urine, and sample analysis was complete in less than 5 min. CONCLUSION: (1)H NMR spectroscopy is a convenient, rapid and economical option for the determination of betaines and related compounds in urine in a single analysis.