Epigenetic scars in regulatory T cells are retained after successful treatment of chronic hepatitis C with direct-acting antivirals.

BACKGROUND & AIMS: Chronic hepatitis C virus (HCV) infection results in abnormal immunological alterations, which are not fully normalized after viral elimination by direct-acting antiviral (DAA) treatment. Here we longitudinally examined phenotypic, transcriptomic, and epigenetic alterations in peripheral blood regulatory T (TREG) cells from patients with chronic HCV infection according to DAA treatment. METHODS: Patients with chronic genotype 1b HCV infection who achieved sustained virologic response (SVR) by DAA treatment and age-matched healthy donors were recruited. Phenotypic characteristics of TREG cells were investigated through flow cytometry analysis. Moreover, transcriptomic and epigenetic landscape of TREG cells were analyzed using RNA-seq and ATAC-seq analysis. RESULTS: The TREG cell population-especially the activated TREG cell subpopulation-was expanded in peripheral blood during chronic HCV infection, and this expansion was sustained even after viral clearance. RNA-seq analysis revealed that viral clearance did not abrogate the inflammatory features of these TREG cells, such as TREG activation and TNF signal. Moreover, ATAC-seq analysis showed inflammatory imprinting in the epigenetic landscape of TREG cells from patients, which remained after treatment. These findings were further confirmed by intracellular cytokine staining, demonstrating that TREG cells exhibited inflammatory features and TNF production in chronic HCV infection that were maintained after viral clearance. CONCLUSIONS: Overall, our results showed that during chronic HCV infection, the expanded TREG cell population acquired inflammatory features at phenotypic, transcriptomic, and epigenetic levels, which were maintained even after successful viral elimination by DAA treatment. Further studies are warranted to examine the clinical significance of sustained inflammatory features in the TREG cell population after recovery from chronic HCV infection. IMPACT AND IMPLICATIONS: During chronic HCV infection, several immune components are altered both quantitatively and qualitatively. The recent introduction of DAAs led to a high cure rate of chronic HCV infection. Nevertheless, we have demonstrated that inflammatory features of TREG cells are maintained at phenotypic, transcriptomic, and epigenetic levels even after successful DAA treatment. Further in-depth studies are required to investigate the long-term clinical outcomes of patients who have recovered from chronic HCV infection.

Trends of antibiotic use at the end-of-life of cancer and non-cancer decedents: a nationwide population-based longitudinal study (2006-2018).

Objective: This study aimed to assess the actual burden of antibiotic use among end-of-life (EOL) patients in South Korea and to compare trends between cancer and non-cancer decedents. Design: Population-based mortality follow-back study. Setting: Data from the Korean National Health Insurance Database, covering the period from January1, 2006, to December 31, 2018, provided for research by the National Health Insurance Service (NHIS), were used. Participants: All decedents from 2006 to 2018 were included and categorized as cancer decedents or non-cancer decedents. Methods: Annual antibiotic consumption rates and prescription rates were calculated, and Poisson regression was used to estimate their trends. Results: Overall antibiotic consumption rates decreased slightly among decedents in their final month with a less pronounced annual decrease rate among cancer decedents compared to non-cancer decedents (0.4% vs 2.3% per year, P <.001). Over the study period, although narrow spectrum antibiotics were used less, utilization and prescription of broad-spectrum antibiotics steadily increased, and prescription rates were higher in cancer decedents compared to non-cancer controls. Specifically, carbapenem prescription rates increased from 5.6% to 18.5%, (RR 1.087, 95% CI 1.085-1.088, P <.001) in cancer decedents and from 2.9% to 13.2% (RR 1.115, 95% CI 1.113-1.116, P <.001) in non-cancer decedents. Conclusions: Our findings show that patients at the EOL, especially those with cancer, are increasingly and highly exposed to broad-spectrum antibiotics. Measures of antibiotic stewardship are required among this population.

Development of a formula for estimated glomerular filtration rate in pregnant women from physiological hyperfiltration of serum creatinine.

Increased body fluids during pregnancy complicates the application of estimated glomerular filtration rate (eGFR) formulas that are based on body surface area. Furthermore, gestational renal dysfunction cannot be identified if the serum creatinine (SCr) concentration is within the non-pregnant reference interval (RI) despite inadequate pregnancy-related renal hyperfiltration. 1484 SCr measurements from 957 healthy pregnant women were collected. The average SCr value of gestational week (GW) 0-3 was the representative SCr value of non-pregnant status. While the distribution of SCr measurements varied across GWs, it was transformed into a normal distribution using the bootstrap resampling method. A polynomial linear regression method was applied to achieve a continuous and smooth transformation of values. The normally distributed SCr values of each GW were compared to the non-pregnant status, leading to the calculation of SCr hyperfiltration. The final equation, (2 - SCr (µmol/L) / 55.25) × 103.1 × 55.25/(56.7 - 0.223 × GW - 0.113 × GW2 + 0.00545 × GW3 - 0.0000653 × GW4), and reference intervals for both SCr and eGFR for each GW were obtained. These RIs and novel equations can be effectively used to monitor renal dysfunction in pregnant women.

False-positive results of galactomannan assays in patients administered glucose-containing solutions.

Galactomannan (GM) is a polysaccharide cell wall component released by Aspergillus spp., and an immunoenzymatic GM assay is used for the diagnosis of invasive pulmonary aspergillosis. We evaluated the cause of strong positivity for GM in patients with no typical signs of aspergillosis. Repeat assays were performed using different instruments and reagent lots, but there were no differences in results among the assays. Patients with strongly positive GM results were investigated. Medication histories revealed that 14 of 23 patients had been administered total parenteral nutrition solution from one manufacturer and 4 patients had been administered dextrose solution from a different manufacturer before being tested. The results of GM assays conducted on samples of dextrose solution and the glucose fraction of the total parenteral nutrition solution were strongly positive, confirming the causes of the false-positive reactions. We hypothesize that a trace amount of GM was introduced into the glucose-containing solutions because glucoamylase, which is necessary for the saccharification step of glucose synthesis, was derived from Aspergillus niger. To enhance patient care and prevent unnecessary antifungal prescriptions, healthcare providers and manufacturers of healthcare products need to be aware of the possibility of false-positive reactions for GM.

Program evaluation of postgraduate obstetrics and gynecology training in Lao people's democratic republic - using the CIPP model.

BACKGROUND: The obstetrics and gynaecology (OB-GYN) residency training program in Lao People's Democratic Republic (PDR) began in 2003 based on the Millennium Development Goals (MDGs) and 'Reproductive, maternal, newborn, and child health interventions (RMNCH) strategies and action plan'. However, the training program had not been properly evaluated previously. The purpose of this study is to evaluate the current postgraduate OB-GYN residency training program in Lao PDR by using CIPP model to identify the current problems (the strengths and weaknesses) and suggest a future plan to promote continuous improvement. METHOD: The context, input, process, and product classification (CIPP) model was used to develop criteria and indicators. A mixed-methods approach was used for this study. To capture instructional material for quantitative analysis, a Google survey with 38 items and a t-test were used to determine a significant difference in responses between residents and lecturers (N = 120). Based on qualitative analysis, an in-depth interview was done (four questions based on study outcomes, including satisfaction, strengths and weaknesses, and future opportunities), and six interviews provided different viewpoints on the course. The SPSS software program was used to measure validity, with p-values = 0.05. RESULTS: The overall average response rate was 97.5%. Two significant differences in program perspectives were revealed between lecturers and residents, difficulties in maintaining the course (professors 3.66 ± 1.03 and residents 3.27 ± 0.98, p = 0.04) and learning outcomes achieved (professors 3.57 ± 0.85 and residents 3.14 ± 0.95, p = 0.01 The overall average for the context part of the questionnaire was under 3.00, with the lowest scores for overlapped learning outcomes and difficulties in maintaining the course. The input part, lack of the classroom, skills lab and staff; the process part, lecturer to collect student opinions and the product part on learning outcomes. CONCLUSION: Curriculum improvement based on the program evaluation results, including regular evaluation and feedback, will advance the residency training program based on the RMNCH strategy and contribute to the promotion of maternal health in the Lao PDR.

Staphylococcus argenteus bacteremia in the Republic of Korea.

In 2015, Staphylococcus argenteus and Staphylococcus schweitzeri were proposed as new species, distinct from Staphylococcus aureus and collectively referred to as the S. aureus complex. However, no clinical reports of these new species exist in Korea. Upon the application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for all bloodstream isolates since September 2022, S. argenteus was identified in one patient. Therefore, we aimed to search for new species among the archives of the S. aureus bacteremia cohort and describe their clinical and microbiological characteristics. Among the 691 archived S. aureus isolates between 2012 and 2018, one was identified as S. argenteus via MALDI-TOF MS. Both S. argenteus isolates (one in 2022) were obtained from patients with extensive pneumonia accompanied by bacteremia and both cases had fatal outcomes. They harbored multiple virulence genes (clfA, clfB, fnbpA, sdrC, sdrD, sdrE, bbp, cna, see, seg, sei, blaZ, fnbpB, and map) but did not harbor mecA and pvl. No matched sequence type (ST) was found in either isolate, and both S. argenteus isolates were closely related to ST1594, ST1593, ST1793, and ST1303, which belonged to S. argenteus. S. argenteus accounted for <1% of the S. aureus complex but had clinical characteristics similar to S. aureus. Therefore, clinicians should be aware of these factors to avoid misidentifying these strains as coagulase-negative staphylococci, and appropriate reporting is required to minimize confusion.IMPORTANCEStaphylococcus argenteus, a member of Staphylococcus aureus complex, has been reported as an important pathogen that causes clinically invasive infections in humans similar to S. aureus. Clinical isolates of S. argenteus have been reported across the world, showing a large geographical difference in prevalence and genomic profile. However, there have been no clinical reports regarding this new species in Korea. This is the first report to investigate the clinical and genetic characteristics of S. argenteus identified in patients with bacteremia, and the proportion of S. argenteus bacteremia among S. aureus bacteremia cohort in Korea.

The biological standard of living of Korean men under Confucianism, colonialism, capitalism, and communism.

This study focuses on analysing the heights of 10,953 Korean men aged 20 to 40 years who were measured during the Joseon dynasty, the Japanese colonialisation period, and the contemporary period, the latter including both North and South Korea. This study thus provides rare long-term statistical evidence on how biological living standards have developed over several centuries, encompassing Confucianism, colonialism, capitalism, and communism. Using error bar analysis of heights for each historical sample period, this study confirms that heights rose as economic performance improved. For instance, economically poorer North Koreans were expectedly shorter, by about 6 cm, than their peers living in the developed South. Similarly, premodern inhabitants of present-day South Korea, who produced a gross domestic product (GDP) per capita below the world average, were about 4 cm shorter than contemporary South Koreans, who have a mean income above the world average. Along similar lines, North Koreans, who have a GDP per capita akin to that of the premodern Joseon dynasty, have not improved much in height. On the contrary, mean heights of North Koreans were even slightly below (by about 2.4 cm) heights of Joseon dynasty Koreans. All in all, the heights follow a U-shaped pattern across time, wherein heights were lowest during the colonial era. Heights bounced back to Joseon dynasty levels during the interwar period, a time period where South Korea benefitted from international aid, only to rise again and surpass even premodern levels under South Korea's flourishing market economy.

Possibility of Decreasing Incidence of Human Immunodeficiency Virus Infection in Korea.

BACKGROUND: The number of newly diagnosed cases of human immunodeficiency virus (HIV) infection in Korea, which had increased until 2019, has markedly decreased since the coronavirus disease 2019 pandemic started. This study evaluated whether the decrease is due to a reduction in the incidence of HIV infection and/or delayed diagnosis during the pandemic. MATERIALS AND METHODS: We reviewed the medical records of 587 newly diagnosed patients with HIV infection between February 2018 and January 2022 from four general hospitals, and their characteristics were compared between the pre-pandemic and pandemic periods. The lapse time from infection to diagnosis was estimated using an HIV modeling tool. RESULTS: The estimated mean times to diagnosis were 5.68 years (95% confidence interval [CI]: 4.45 - 6.51 years) and 5.41 years (95% CI: 4.09 - 7.03 years) before and during the pandemic, respectively (P = 0.016). The proportion of patients with acquired immunodeficiency syndrome-defining illnesses, expected to visit hospitals regardless of the pandemic, decreased from 17.2% before the pandemic to 11.9% during the pandemic (P = 0.086). CONCLUSION: The decrease in the number of newly diagnosed cases of HIV infection in Korea might have resulted from an actual decrease in the incidence of HIV infection rather than a worsening of underdiagnosis or delayed diagnosis.

Synthesis of 1-(2,2-Dimethylpropyl)-Cyclopropene (1-DCP) as an Ethylene Antagonist.

Ethylene is a gaseous hydrocarbon molecule known as a plant hormone that promotes fruit ripening and senescence. Efficiently controlling ethylene is a central key to maintaining the quality of agricultural products. The current study uncovered a synthetic method for 1-(2,2-dimethylpropyl)-cyclopropene (1-DCP) as a cyclopropene derivative to inhibit ethylene action in fruit ripening and senescence. We synthesized 1-DCP using α-diisobutylene through a two-step process, including allylic chlorination by hypochlorite and HCl, followed by α-elimination of the allylic chloride using a strong base, lithium diethylamide. GC-MS and NMR analyses demonstrated that 1-DCP was synthesized efficiently with 35% yield and 95% purity. When treated as an aqueous emulsion on plants, including persimmon and banana fruits, 1 mM 1-DCP showed effective inhibition of ethylene action by delaying the flesh softening and peel degreening, which are representative phenomena of fruit ripening and senescence induced by ethylene. Our data demonstrated that 1-DCP could be synthesized and used as a sprayable ethylene antagonist for pre- or post-harvest growth regulation in plants and fruits.

Prediction Model for Pre-Eclampsia Using Gestational-Age-Specific Serum Creatinine Distribution.

Pre-eclampsia (PE) is a pregnancy-related disease, causing significant threats to both mothers and babies. Numerous studies have identified the association between PE and renal dysfunction. However, in clinical practice, kidney problems in pregnant women are often overlooked due to physiologic adaptations during pregnancy, including renal hyperfiltration. Recent studies have reported serum creatinine (SCr) level distribution based on gestational age (GA) and demonstrated that deviations from the expected patterns can predict adverse pregnancy outcomes, including PE. This study aimed to establish a PE prediction model using expert knowledge and by considering renal physiologic adaptation during pregnancy. This retrospective study included pregnant women who delivered at the Wonju Severance Christian Hospital. Input variables, such as age, gestational weeks, chronic diseases, and SCr levels, were used to establish the PE prediction model. By integrating SCr, GA, GA-specific SCr distribution, and quartile groups of GA-specific SCr (GAQ) were made. To provide generalized performance, a random sampling method was used. As a result, GAQ improved the predictive performance for any cases of PE and triple cases, including PE, preterm birth, and fetal growth restriction. We propose a prediction model for PE consolidating readily available clinical blood test information and pregnancy-related renal physiologic adaptations.

Antibiotic Prescription in Patients With Coronavirus Disease 2019: Analysis of National Health Insurance System Data in the Republic of Korea.

BACKGROUND: Although coronavirus disease 2019 (COVID-19) is a viral infection, antibiotics are often prescribed due to concerns about accompanying bacterial infection. Therefore, we aimed to analyze the number of patients with COVID-19 who received antibiotic prescriptions, as well as factors that influenced antibiotics prescription, using the National Health Insurance System database. METHODS: We retrospectively reviewed claims data for adults aged ≥ 19 years hospitalized for COVID-19 from December 1, 2019 to December 31, 2020. According to the National Institutes of Health guidelines for severity classification, we calculated the proportion of patients who received antibiotics and the number of days of therapy per 1,000 patient-days. Factors contributing to antibiotic use were determined using linear regression analysis. In addition, antibiotic prescription data for patients with influenza hospitalized from 2018 to 2021 were compared with those for patients with COVID-19, using an integrated database from Korea Disease Control and Prevention Agency-COVID19-National Health Insurance Service cohort (K-COV-N cohort), which was partially adjusted and obtained from October 2020 to December 2021. RESULTS: Of the 55,228 patients, 46.6% were males, 55.9% were aged ≥ 50 years, and most patients (88.7%) had no underlying diseases. The majority (84.3%; n = 46,576) were classified as having mild-to-moderate illness, with 11.2% (n = 6,168) and 4.5% (n = 2,484) having severe and critical illness, respectively. Antibiotics were prescribed to 27.3% (n = 15,081) of the total study population, and to 73.8%, 87.6%, and 17.9% of patients with severe, critical, and mild-to-moderate illness, respectively. Fluoroquinolones were the most commonly prescribed antibiotics (15.1%; n = 8,348), followed by third-generation cephalosporins (10.4%; n = 5,729) and beta-lactam/beta-lactamase inhibitors (6.9%; n = 3,822). Older age, COVID-19 severity, and underlying medical conditions contributed significantly to antibiotic prescription requirement. The antibiotic use rate was higher in the influenza group (57.1%) than in the total COVID-19 patient group (21.2%), and higher in severe-to-critical COVID-19 cases (66.6%) than in influenza cases. CONCLUSION: Although most patients with COVID-19 had mild to moderate illness, more than a quarter were prescribed antibiotics. Judicious use of antibiotics is necessary for patients with COVID-19, considering the severity of disease and risk of bacterial co-infection.

Case Report and Literature Review of Occupational Transmission of Monkeypox Virus to Healthcare Workers, South Korea.

We report a case of occupational monkeypox virus infection from a needlestick injury in a healthcare worker in South Korea and review similar reports in the literature during 2022. Postexposure prophylactic treatment with a third-generation smallpox vaccine and antiviral agent tecovirimat inhibited local virus spread and alleviated lesion pain.

KIR+CD8+ and NKG2A+CD8+ T cells are distinct innate-like populations in humans.

Subsets of the human CD8+ T cell population express inhibitory NK cell receptors, such as killer immunoglobulin-like receptors (KIRs) and NKG2A. In the present study, we examine the phenotypic and functional characteristics of KIR+CD8+ T cells and NKG2A+CD8+ T cells. KIRs and NKG2A tend to be expressed by human CD8+ T cells in a mutually exclusive manner. In addition, TCR clonotypes of KIR+CD8+ T cells barely overlap with those of NKG2A+CD8+ T cells, and KIR+CD8+ T cells are more terminally differentiated and replicative senescent than NKG2A+CD8+ T cells. Among cytokine receptors, IL12Rß1, IL12Rß2, and IL18Rß are highly expressed by NKG2A+CD8+ T cells, whereas IL2Rß is expressed by KIR+CD8+ T cells. IL-12/IL-18-induced production of IFN-γ is prominent in NKG2A+CD8+ T cells, whereas IL-15-induced NK-like cytotoxicity is prominent in KIR+CD8+ T cells. These findings suggest that KIR+CD8+ and NKG2A+CD8+ T cells are distinct innate-like populations with different cytokine responsiveness.

Sodium dichloroisocyanurate toxicity in rats during a 90-day inhalation toxicity study.

Sodium dichloroisocyanurate-96% (NaDCC) is commonly used to treat drinking water, industrial water, and wastewater. However, exposure to NaDCC by inhalation can have toxic pulmonary effects in humans. In the present study, we evaluated the potential toxicity of NaDCC following a 90-day inhalation toxicity study in Sprague-Dawley/Crl:CD (SD) rats. The animals were exposed to 0.4, 2.0, or 10.0 mg/m3 NaDCC for 90 days. In addition, male and female rats from the 10.0 mg/m3 group were set up as the recovery group for 14 days. The bronchoalveolar lavage fluid showed a concentration-dependent increase in the total cell count, with a significant increase in neutrophils in both the sexes in the 10.0 mg/m3 group compared to the negative control group. In the 10.0 mg/m3 group, lung organ weight was significantly increased among the female rats. Histopathological examination showed eosinophilic droplets in the olfactory/respiratory epithelium, mucous cell hyperplasia, atrophy/degeneration of the tracheal branches, and wall thickening of the alveolar ducts in the nasal cavity of both sexes in the 10.0 mg/m3 group. The adverse effects of NaDCC exposure were observed to decrease during the 14-day recovery period in both sexes. Based on pathological observations, the "no observed adverse effect concentration (NOAEC)" of inhaled NaDCC was 2.0 mg/m3 for both sexes. These results are expected to provide a scientific basis for inhalation toxicity data of NaDCC.

Diagnostic Performance, Stability, and Usability of Self-Collected Combo Swabs and Saliva for Coronavirus Disease 2019 Diagnosis: A Case-Control Study.

BACKGROUND: Self-sampling procedures to detect severe acute respiratory syndrome coronavirus 2 is important for patients who have difficulty visiting the hospital and may decrease the burden for health care workers (HCWs). The objective of this study was to evaluate the diagnostic performance, stability and usability of self-collected nasal and oral combo swabs and saliva specimens. MATERIALS AND METHODS: We conducted a case-control study with 50 patients with coronavirus disease 2019 (COVID-19) and 50 healthy volunteers from March, 2021 to June, 2021. We performed real-time reverse-transcription polymerase chain reaction to compare the diagnostic performance of self-collected specimens using positive percent agreements (PPAs). RESULTS: The PPAs between self-collected and HCW-collected specimens were 77.3 - 81.0% and 80.5 -86.7% for the combo swabs and saliva specimens, respectively. The PPAs increased to 88.9 - 89.2% and 81.2 - 82.1% with a cycle threshold value ≤30. CONCLUSION: The diagnostic performance of self sampling was comparable to that of HCW sampling in patients with high viral loads and may thus assist in the early diagnosis of COVID-19.

A Retrospective National Study on Colonization Rate and Antimicrobial Susceptibility of Streptococcus agalactiae in Pregnant Korean Women, 2018-2020.

PURPOSE: The prevalence of Group B Streptococcus (GBS) colonization in pregnant Korean women is increasing; however, nationwide studies are lacking. Therefore, we aimed to analyze regional colonization rates and antimicrobial susceptibility for GBS in pregnant Korean women through a nationwide survey. MATERIALS AND METHODS: From January 2018 to December 2020, data from the Seoul Clinical Laboratories on vaginal swab cultures were retrospectively analyzed to detect maternal GBS carriers. Each swab specimen was inoculated onto a 5% blood agar plate and incubated at 35℃-37℃ in a 5% CO2 incubator for 24 h. GBS isolates were identified using a Microflex MALDI Biotyper. Antimicrobial susceptibility tests were performed using the Vitek 2 automated system. RESULTS: The overall nationwide GBS colonization rate in pregnant Korean women was found to be 10.6% (3578/33721). The maternal GBS colonization rates ranged from 10.5%-10.8% over the 3-year study period. The GBS colonization rates by province, in descending order, were as follows: Jeolla-do, 13.2%; Gangwon-do, 12.0%; Chungcheong-do, 11.8%; Gyeonggi-do, 11.3%; Seoul, 10.2%; and Gyeongsang-do, 9.6%. During the study period, the resistance rates against chloramphenicol, levofloxacin, clindamycin, erythromycin, and tetracycline were 2.6%-2.7%, 18.2%-19.6%, 33.4%-35.7%, 35.6%-36.8%, and 50.5%-53.3%, respectively. CONCLUSION: In pregnant Korean women, GBS colonization rates were in the range of 9.6%-13.2%, with Gyeongsang-do being the lowest and Jeolla-do the highest. The resistance rate against clindamycin was high (33.4%-35.7%). GBS colonization rates during pregnancy should be studied nationwide according to the Centers for Disease Control and Prevention-recommended guidelines with periodic antimicrobial resistance monitoring.

Gestational age-specific serum creatinine can predict adverse pregnancy outcomes.

Serum creatinine level (SCr) typically decreases during pregnancy due to physiologic glomerular hyperfiltration. Therefore, the clinical practice of estimated glomerular filtration rate (eGFR) based on SCr concentrations might be inapplicable to pregnant women with kidney disease since it does not take into account of the pregnancy-related biological changes. We integrated the Wonju Severance Christian Hospital (WSCH)-based findings and prior knowledge from big data to reveal the relationship between the abnormal but hidden SCr level and adverse pregnancy outcomes. We analyzed 4004 pregnant women who visited in WSCH. Adverse pregnancy outcomes included preterm birth, preeclampsia, fetal growth retardation, and intrauterine fetal demise. We categorized the pregnant women into four groups based on the gestational age (GA)-unadjusted raw distribution (Q1-4raw), and then GA-specific (Q1-4adj) SCr distribution. Linear regression analysis revealed that Q1-4adj groups had better predictive outcomes than the Q1-4raw groups. In logistic regression model, the Q1-4adj groups exhibited a robust non-linear U-shaped relationship with the risk of adverse pregnancy outcomes, compared to the Q1-4raw groups. The integrative analysis on SCr with respect to GA-specific distribution could be used to screen out pregnant women with a normal SCr coupled with a decreased renal function.