Hemodialysis with Cohort Isolation to Prevent Secondary Transmission during a COVID-19 Outbreak in Korea.

BACKGROUND: Health care-associated infections during previous coronavirus epidemics involving severe acute respiratory syndrome and Middle East respiratory syndrome resulted from human-to-human transmission in hemodialysis (HD) facilities. The effect of a strategy of HD with cohort isolation-separate dialysis sessions for close contacts of patients with confirmed coronavirus disease 2019 (COVID-19)-on the prevention of secondary transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in HD units is unknown. METHODS: Our multicenter cohort study of an HD with cohort isolation strategy enrolled close contacts of patients with confirmed COVID-19, including patients on HD and health care workers in HD units. Close contacts had been identified by epidemiologic investigation and tested negative on an immediate screening test for SARS-CoV-2. RESULTS: As of March 14, 11 patients on HD and 7 health care workers from 11 HD centers were diagnosed as having COVID-19. The immediate screening test was performed in 306 people, and among them, 302 close contacts with negative test results were enrolled. HD with cohort isolation was performed among all close contacts for a median of 14 days in seven centers. During cohort isolation, nine patients showed symptoms but tested negative for SARS-CoV-2. Two health care workers in the HD units (0.66% of the total group) were diagnosed at the termination test for SARS-CoV-2. CONCLUSIONS: The transmission of COVID-19 can be controlled without closure of HD centers by implementing preemptive activities, including early detection with rapid testing, cohort isolation, collaboration between institutions, and continuous monitoring of infection. Our strategy and experience may provide helpful guidance for circumstances involving the rapid spread of infectious diseases such as COVID-19.

Low Non-NMDA Receptor Current Density as Possible Protection Mechanism from Neurotoxicity of Circulating Glutamate on Subfornical Organ Neurons in Rats.

The subfornical organ (SFO) is one of circumventricular organs characterized by the lack of a normal blood brain barrier. The SFO neurons are exposed to circulating glutamate (60~100 µM), which may cause excitotoxicity in the central nervous system. However, it remains unclear how SFO neurons are protected from excitotoxicity caused by circulating glutamate. In this study, we compared the glutamate-induced whole cell currents in SFO neurons to those in hippocampal CA1 neurons using the patch clamp technique in brain slice. Glutamate (100 µM) induced an inward current in both SFO and hippocampal CA1 neurons. The density of glutamate-induced current in SFO neurons was significantly smaller than that in hippocampal CA1 neurons (0.55 vs. 2.07 pA/pF, p<0.05). To further identify the subtype of the glutamate receptors involved, the whole cell currents induced by selective agonists were then compared. The current densities induced by AMPA (0.45 pA/pF) and kainate (0.83 pA/pF), non-NMDA glutamate receptor agonists in SFO neurons were also smaller than those in hippocampal CA1 neurons (2.44 pA/pF for AMPA, p<0.05; 2.34 pA/pF for kainate, p< 0.05). However, the current density by NMDA in SFO neurons was not significantly different from that of hippocampal CA1 neurons (1.58 vs. 1.47 pA/pF, p>0.05). These results demonstrate that glutamate-mediated action through non-NMDA glutamate receptors in SFO neurons is smaller than that of hippocampal CA1 neurons, suggesting a possible protection mechanism from excitotoxicity by circulating glutamate in SFO neurons.

COVID-19-related clinical outcomes among Korean hemodialysis patients.

BACKGROUND: Hemodialysis (HD) patients are more vulnerable to viral epidemics, experiencing higher mortality rates compared to individuals without chronic kidney disease (CKD). This retrospective cohort study sought to demonstrate clinical outcomes and associated factors among coronavirus disease 2019 (COVID-19) confirmed Korean HD patients. METHODS: From February 2020 to November 2021, the COVID-19 Task Force Team collected clinical data for HD patients with confirmed COVID-19 via a self-report survey of nephrologists. The composite outcome included in-hospital mortality, admission to the intensive care unit (ICU), and use of mechanical ventilation. Risk factors associated with clinical outcomes were analyzed among HD patients and compared to those of individuals without CKD using the COVID-19 database from the Korea Disease Control and Prevention Agency. RESULTS: A total of 380 HD patients from 206 facilities were diagnosed with COVID-19. Fever (49.5%) and cough (25.7%) were the two most common initial symptoms. The overall in-hospital fatality rate was 22.4% and even higher among ICU admission cases (64.7%). Non-survivors were older, more frequently developed shortness of breath, and were more likely to come from a nursing hospital. Compared to the age- and sex-matched non-CKD population, HD patients showed greater risk of in-hospital mortality (hazard ratio, 2.07; 95% confidence interval, 1.56-2.75; p < 0.001) and composite outcome (hazard ratio, 3.50; 95% confidence interval, 2.56-4.77; p < 0.001). CONCLUSION: HD patients have a greater risk of in-hospital mortality and morbidity from COVID-19. Special attention should be paid to COVID-19 HD patients when they are older or present with symptoms.

A Comparative Study on Aqueous Chitosan Solution and Various Submucosal Injection Fluids Using a Three-Dimensional Sensor.

BACKGROUND/AIMS: Chitosan, a natural polymer widely used in the biomaterials field, has been proposed as a potential submucosal injection solution. The purpose of this study was to compare the performance and efficacy of aqueous chitosan solution and commercialized submucosal injection fluids using a three-dimensional sensor and to evaluate the efficacy of the measured parameters. METHODS: Normal saline (0.9% NaCl), as a control, Eleview® (Poloxamer 188), Blue EyeTM (0.4% hyaluronic acid), and aqueous chitosan solution (2.0%) were injected into the submucosa of porcine stomachs ex vivo. The mucosal elevation height, elevated surface area, and angle of the tangent of the submucosal fluid cushion were measured using a three-dimensional sensor. The rates of change for each variable were calculated, and the correlation between parameters was analyzed. Tissue specimens were stained with hematoxylin and eosin. RESULTS: All variables exhibited the highest values under chitosan injection. The mucosal elevation height rate of change differed significantly between normal saline and chitosan solution (p=0.024). The elevated surface area rates of change for normal saline and Eleview® were significantly different from those for TS-905 and chitosan solution (p=0.006 and p=0.009, respectively). Further, height, area, and angle showed a positive correlation (p<0.001). A histological examination revealed an even distribution of aqueous chitosan within the submucosa without tissue damage. CONCLUSIONS: Aqueous chitosan was superior to normal saline and Eleview® and was noninferior to TS-905. A three-dimensional sensor and the measured parameters were effective and useful for evaluating the performance of submucosal fluids.

Effects of Actin Cytoskeleton Disruption on Electroporation In Vitro.

The role of actin fibers in cellular responses to external electric pulses is not clear yet. In this study, we utilized the blocker of actin polymerization, cytochalasin D (cytoD), and investigated its effects on the electropore generation. Eight 100 µs electric pulses of sub-kilovolt per centimeter voltage with 100 ms intervals were applied to adhered cells in vitro, and the membrane permeability was quantified using membrane-impermeable propidium iodide (PI) dye. With cytoD application, the transfer of PI dye decreased significantly in all the applied voltages. At the same time, the roughness of cells increased, the membrane stiffness decreased, and the transmembrane resting potential decreased. Our result supports that actin fibers have clear effects on electroporation through modulating membrane properties including transmembrane resting potential.

Korean clinical practice guidelines for preventing transmission of coronavirus disease 2019 (COVID-19) in hemodialysis facilities.

Coronavirus disease 2019 (COVID-19) is a highly contagious viral disease that is caused by the novel virus Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). COVID-19 has become pandemic since December 2019, when the first case developed in Wuhan, China. Patients receiving hemodialysis are more vulnerable to viral transmission because their immune functions are impaired and they receive treatment within a narrow space. Calling on previous experience with Middle East Respiratory Syndrome during the 2015 outbreak, the joint committee of the Korean Society of Nephrology and the Korean Society of Dialysis Therapy quickly formed a COVID-19 task force team to develop a manual before the first index case was diagnosed in the hemodialysis unit. This special article introduces clinical practice guidelines to prevent secondary transmission of COVID-19 within hemodialysis facilities, which were developed to protect patients, healthcare workers, and caregivers from this highly transmissible virus. The areas of infection control covered by these guidelines include standard precautions, performing dialysis therapy for confirmed or suspected cases, performing cohort isolation for contact patients, and disease monitoring and contact surveillance. We hope these guidelines help healthcare workers and hemodialysis patients around the world cope with the COVID-19 pandemic.

Middle East respiratory syndrome clinical practice guideline for hemodialysis facilities.

The Korean Society of Nephrology participated in the task force team consisting of government authorities and civilian experts to prevent and control the spread of Middle East respiratory syndrome (MERS) in 2015. The Korean Society of Nephrology MERS Task Force Team took an immediate action and drafted 'the clinical recommendation for hemodialysis facilities' to follow when the first and the only confirmed case was reported in the hemodialysis unit. Owing to the dedicated support from medical doctors, dialysis nurses, and related medical companies, we could prevent further transmission of MERS infection successfully in hemodialysis units. This special report describes the experience of infection control during MERS outbreak in 2015 and summarizes the contents of 'the clinical practice guideline for hemodialysis facilities dealing with MERS patients' built upon our previous experience.

Serum globotriaosylceramide assay as a screening test for fabry disease in patients with ESRD on maintenance dialysis in Korea.

BACKGROUND/AIMS: Fabry disease is an X-linked recessive and progressive disease caused by α-galactosidase A (α-GaL A) deficiency. We sought to assess the prevalence of unrecognized Fabry disease in dialysis-dependent patients and the efficacy of serum globotriaosylceramide (GL3) screening. METHODS: A total of 480 patients of 1,230 patients among 17 clinics were enrolled. Serum GL3 levels were measured by tandem mass spectrometry. Additionally, we studied the association between increased GL3 levels and cardiovascular disease, cerebrovascular disease, or left ventricular hypertrophy. RESULTS: Twenty-nine patients had elevated serum GL3 levels. The α-GaL A activity was determined for the 26 patients with high GL3 levels. The mean α-GaL A activity was 64.6 nmol/hr/mg (reference range, 45 to 85), and no patient was identified with decreased α-GaL A activity. Among the group with high GL3 levels, 15 women had a α-GaL A genetics analysis. No point mutations were discovered among the women with high GL3 levels. No correlation was observed between serum GL3 levels and α-GaL A activity; the Pearson correlation coefficient was 0.01352 (p = 0.9478). No significant correlation was observed between increased GL3 levels and the frequency of cardiovascular disease or cerebrovascular disease. CONCLUSIONS: Fabry disease is very rare disease in patients with end-stage renal disease. Serum GL3 measurements as a screening method for Fabry disease showed a high false-positive rate. Thus, serum GL3 levels determined by tandem mass spectrometry may not be useful as a screening method for Fabry disease in patients with end stage renal disease.