Patterns in renal diseases diagnosed by kidney biopsy: A single-center experience

Background

The worldwide incidence of renal disease diagnosed by a kidney biopsy varies with age, race, sex, and region. Owing to a lack of studies and limited research resources for this disease in Korea, we investigated renal disease patterns by analyzing data from kidney biopsies performed over 13 years in a university-based teaching hospital in Korea.

Methods

Among 2,053 kidney biopsies performed from 2001 to 2013 at Kyungpook National University Hospital, 1,924 were retrospectively analyzed for histopathologic, demographic, and clinical data as well as laboratory results.

Results

Among the 1,924 studied kidney biopsies, 1,078 were males (56.0%) and the mean age was 37.7 ± 16.5 years. Asymptomatic urinary abnormalities were the most common clinical manifestation (62.5%). Immunoglobulin A nephropathy (IgAN) was the most common primary glomerular disease (37.4%), followed by minimal change disease (MCD), membranous nephropathy (MN), focal segmental glomerulonephritis and crescentic glomerulonephritis. Secondary glomerular diseases accounted for 10.3% of the total biopsies, with lupus nephritis being the most common (4.6%) followed by Henoch-Schönlein purpura nephritis and diabetic nephropathy. The most common cause of nephrotic syndrome was MCD (42.1%) followed by MN. Among patients seropositive for hepatitis B or C, IgAN (28.3% and 21.4%, respectively) was the most common cause.

Conclusion

IgAN and lupus nephritis were the most common primary and secondary glomerular diseases, respectively. Race, region, and practice patterns may affect renal disease patterns in different cohorts.

Computer simulations of X-ray phase-contrast images and microtomographic observation of tubules in dentin

An investigation of the problems of X-ray imaging of dentinal tubules is presented. Two main points are addressed. In the first part of this paper, the problem of computer simulating tubule images recorded in a coherent synchrotron radiation (SR) beam has been discussed. A phantom material which involved a two-dimensional lattice of the tubules with parameters similar to those of dentin was considered. By a comparative examination of two approximations, it was found that the method of phase-contrast imaging is valid if the number of tubules along the beam is less than 100. Calculated images from a lattice of 50 × 50 tubules are periodic in free space but depend strongly on the distance between the specimen and the detector. In the second part, SR microtomographic experiments with millimetre-sized dentin samples in a partially coherent beam have been described. Tomograms were reconstructed from experimental projections using a technique for incoherent radiation. The main result of this part is the three-dimensional rendering of the directions of the tubules in a volume of the samples. Generation of the directions is possible because a tomogram shows the positions of the tubules. However, a detailed tubule cross-section structure cannot be restored.

Association of Hepcidin With Anemia Parameters in Incident Dialysis Patients: Differences Between Dialysis Modalities

Hepcidin's relationships with other variables are unclear. We evaluated associations of serum hepcidin with clinical parameters in ESRD patients. Ninety-nine incident dialysis patients, including 57 on peritoneal dialysis (PD) and 42 on HD, were prospectively followed for 6 months. Serum hepcidin levels significantly increased during initial 6 months of dialysis. In the multivariate regression model, independent predictors of serum hepcidin levels in ESRD patients before maintenance dialysis were interleukin-6, ferritin, phosphate, iron, and aspartate transaminase. Six months after initiating dialysis, serum hepcidin levels were independently predicted by ferritin, total iron binding capacity (TIBC), and aspartate transaminase in all patients, whereas by ferritin and TIBC in PD patients, and ferritin, TIBC, and 24-h urine volume in HD patients. Serum hepcidin levels are differentially associated with anemia parameters in PD compared with HD patients. Urine volume was an independent predictor of hepcidin levels in early HD patients.

Alpha-1 antitrypsin inhibits formaldehyde-induced apoptosis of human peritoneal mesothelial cells

BACKGROUND

The alpha-1 antitrypsin (AAT) protein has an important role in the anti-inflammatory and apoptotic response. AAT inhibits not only serine proteases but also cysteine and aspartic proteases. Apoptosis results from the sequential activation of cysteine proteases of the caspase family. This study aimed to evaluate the effect of AAT on formaldehyde-induced apoptosis of human peritoneal mesothelial cells (HPMCs).

METHODS

HPMCs were cultured and treated with formaldehyde (250 µM) to induce apoptosis. In the AAT group, the cultured HPMCs were pretreated with AAT (2 mg/mL) for 1 h before formaldehyde treatment. We used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays to determine cell viability, and flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assays to detect apoptosis. The MTT assays were used to find optimal concentrations of formaldehyde and AAT. We measured caspase-3 activity and used Western blotting to estimate Bcl-2 and Bad expression.

RESULTS

Flow cytometry and TUNEL assays revealed that formaldehyde exposure significantly increased apoptosis compared with the control treatment, but pretreatment with AAT significantly inhibited this effect. Compared with the control, caspase-3 activity was significantly increased and the ratio of Bcl-2 to Bad expression significantly decreased following treatment with formaldehyde. However, caspase-3 activity was significantly lower and the Bcl-2 to Bad expression ratio higher in the AAT group than in the formaldehyde-only group.

CONCLUSION

AAT inhibits formaldehyde-induced apoptosis of HPMCs via a caspase-mediated pathway. These data support a potential use for AAT as a therapeutic agent for the inhibition of peritoneal cell apoptosis during peritoneal dialysis.

Outcomes of open heart surgery in patients with end-stage renal disease

Background

Cardiovascular diseases of chronic dialysis patients are often undertreated because of their higher surgical risk. This study aimed to assess mortality and morbidity after open heart surgery in chronic dialysis patients compared to those with normal renal function and identify risk factors for postoperative outcomes.

Methods

We retrospectively analyzed 2,432 patients who underwent open heart surgery from 2002 to 2017 and collected data from 116 patients (38 patients on dialysis and 78 age-, sex-, and diabetes mellitus status-matched control patients with normal kidney function). We assessed comorbidities, New York Heart Association (NYHA) class, laboratory data, surgical methods, and postoperative outcomes.

Results

The dialysis group had more comorbidities, higher NYHA classes, and greater need for urgent surgeries compared to the control group. They exhibited significantly higher postoperative mortality (18.4% vs. 2.6%, P = 0.005) and more overall complications (65.8% vs. 25.6%, P < 0.001). Dialysis itself significantly increased relative risk for inhospital mortality after adjustment. EuroSCORE II was not as useful as in the general population. Multivariate logistic regression analysis demonstrated that total (adjusted odds ratio [AOR], 10.7; P = 0.029) and in-hospital death risk (AOR, 14.7; P = 0.033), the durations of postoperative hospitalization (AOR, 4.6; P = 0.034), CRRT (AOR 36.8; P = 0.004), and ventilator use (AOR, 7.6; P = 0.022) were significantly increased in the dialysis group.

Conclusion

The dialysis group exhibited a higher risk for mortality and overcall complications after open heart surgery compared to the patients with normal renal function. Therefore, the benefit of surgical treatment must be balanced against potential risks.

Impact of Conversion From Cyclosporine to Tacrolimus on Glucose Metabolism and Cardiovascular Risk Profiles in Long-Term Stable Kidney Transplant Recipients

BACKGROUND

Compared to tacrolimus, cyclosporine increases cardiovascular risk. Furthermore, tacrolimus has a negative effect on glucose metabolism compared to cyclosporine. This study investigated the effect of the conversion from cyclosporine to tacrolimus for immunosuppressive therapy on glucose metabolism and cardiovascular risk profiles in long-term stable kidney transplant recipients (KTRs).

METHODS

In this prospective, open-label, single-arm study, 36 KTRs were enrolled; 3 were excluded. Patients were evaluated for glucose metabolism and cardiovascular risk factors at baseline, 3, and 6 months after conversion of medication. Serial changes were analyzed by repeated analysis of variance.

RESULTS

The mean duration from transplantation was 12.6 ± 4.0 years and baseline serum creatinine levels were 1.10 ± .23 mg/dL. After conversion, fasting plasma glucose levels increased sequentially from 101.7 ± 18.5 to 107.4 ± 21.3 mg/dL (P = .007), and glycated hemoglobin levels increased from 5.7 ± .8 to 6.0 ± 1.2% (P = .016). Among cardiovascular risk factors, fibrinogen levels were decreased (P = .015), but other factors, including blood pressure and lipid profile, did not change (all P > .05). There was no change in renal function, including serum creatinine (P = .611) and urine protein-to-creatinine ratio (P = .092). Body mass index levels were decreased (P = .037) and body weight tended to decrease (P = .063).

CONCLUSIONS

Switching immunosuppressant therapy to tacrolimus has an apparent negative effect on glucose metabolism and imparts an unclear advantage on cardiovascular risk profiles for long-term stable KTRs.

Influence of carbonaceous species on aqueous photo-catalytic nitrogen fixation by titania

For decades, reports have suggested that photo-catalytic nitrogen fixation by titania in an aqueous environment is possible. Yet a consensus does not exist regarding how the reaction proceeds. Furthermore, the presence of an aqueous protonated solvent and the similarity between the redox potential for nitrogen and proton reduction suggest that ammonia production is unlikely. Here, we re-investigate photo-catalytic nitrogen fixation by titania in an aqueous environment through a series of photo-catalytic and electrocatalytic experiments. Photo-catalytic testing reveals that mineral phase and metal dopants play a marginal role in promoting nitrogen photofixation, with ammonia production increasing when the majority phase is rutile and with iron dopants. However, the presence of a trace amount of adsorbed carbonaceous species increased the rate of ammonia production by two times that observed without adsorbed carbon based species. This suggests that carbon species play a potential larger role in mediating the nitrogen fixation process over mineral phase and metal dopants. We also demonstrate an experimental approach aimed to detect low-level ammonia production from photo-catalysts using rotating ring disk electrode experiments conducted with and without illumination. Consistent with the photocatalysis, ammonia is only discernible at the ring with rutile phase titania, but not with mixed-phase titania. Rotating ring disk electrode experiments may also provide a new avenue to attain a higher degree of precision in detecting ammonia at low levels.

Severe Respiratory Syncytial Virus Pneumonia in a Kidney Transplant Recipient With Desensitization: Case Report and Comprehensive Review of the Literature

Herein, we report a rare case of severe respiratory syncytial virus pneumonia after kidney transplant in a 46-year-old woman. The patient was diagnosed with end-stage renal disease and underwent living-donor kidney transplant. Direct flow cytometry crossmatch testing yielded positive results, and desensitization treatment with rituximab, plasmapheresis, and im-munoglobulin was performed before transplant. There were no complications. Five days after discharge, the patient was readmitted with a 2-day history of fever and diagnosed with bilateral pneumonia. The patient was placed on mechanical ventilation and given renal replacement therapy. Respiratory syncytial virus in the bronchial washings was detected via polymerase chain reaction. Broad-spectrum antibiotics, intravenous methylprednisolone, and immunoglobulin were admin-istered. Over-immunosuppression strategies, such as desensitization therapy, may result in severe respiratory syncytial virus pneumonia, even in kidney transplant recipients.

Anti-phospholipase A2 receptor antibody as a prognostic marker in patients with primary membranous nephropathy

Background

Phospholipase A2 receptor (PLA2R) has been identified as a major autoantigen in primary membranous nephropathy (MN). We evaluated the association between anti-PLA2R antibodies and clinical outcome in Korean patients with primary MN.

Methods

A total of 66 patients with biopsy-proven MN were included. Serum level of anti-PLA2R antibodies was measured by enzyme-linked immunosorbent assay. Biochemical parameters were estimated initially and at follow-up.

Results

Anti-PLA2R antibodies were detected in 52.1% and 27.8% of patients with primary and secondary MN, respectively. Forty-eight patients with primary MN were grouped based on presence or absence of anti-PLA2R antibodies. Proteinuria was more severe in anti-PLA2R-positive patients than in anti-PLA2R-negative patients (urine protein/creatinine ratio 7.922 ± 3.985 g/g vs. 4.318 ± 3.304 g/g, P = 0.001), and anti-PLA2R antibody level was positively correlated with proteinuria. The incidence of chronic kidney disease stage ≥ 3 was higher in anti-PLA2R-positive patients compared with anti-PLA2R-negative patients (P = 0.004). The probabilities of spontaneous remission were higher in anti-PLA2R-negative patients compared with anti-PLA2R-positive patients (P < 0.001). Multivariate analysis demonstrated that anti-PLA2R antibodies are an independent risk factor for developing chronic kidney disease stage ≥ 3 and for not reaching spontaneous remission.

Conclusion

Detection of anti-PLA2R antibodies at diagnosis in patients with primary MN can predict prognosis and guide treatment decisions.

Novel urinary exosomal biomarkers of acute T cell-mediated rejection in kidney transplant recipients: A cross-sectional study

BACKGROUND

Acute rejection is hazardous to graft survival in kidney transplant recipients (KTRs). We aimed to identify novel biomarkers for early diagnosis of acute T cell-mediated rejection (TCMR) in urinary exosomes of KTRs.

METHODS

Among 458 graft biopsies enrolled in a cross-sectional multicenter study, 22 patients with stable graft function (STA) who had not shown pathologic abnormality and 25 patients who diagnosed biopsy-proven TCMR were analyzed. We performed proteomic analysis using nano-ultra performance liquid chromatography-tandem mass spectrometry (nano-UPLC-MS/MS) to identify candidate biomarkers for early TCMR diagnosis on urinary exosomes. We confirmed the protein levels of each candidate biomarker by western blot analysis.

RESULTS

A total of 169 urinary exosome proteins were identified by nano-UPLC-MS/MS. Forty-six proteins showed increased expression in STA patients, while 17 proteins were increased in TCMR patients. Among them, we selected five proteins as candidate biomarkers for early diagnosis of TCMR according to significance, degree of quantity variance, and information from the ExoCarta database. We confirmed the proteomic expression levels of five candidate biomarkers by western blot analysis in each patient. Of all candidate biomarkers, tetraspanin-1 and hemopexin were significantly higher in TCMR patients (STA:TCMR ratio = 1:1.8, P = 0.009, and 1:3.5, P = 0.046, respectively).

CONCLUSIONS

Tetraspanin-1 and hemopexin were detected in KTR urine and could act as potential diagnostic proteins for TCMR.

Ga-Doped Pt-Ni Octahedral Nanoparticles as a Highly Active and Durable Electrocatalyst for Oxygen Reduction Reaction

Bimetallic PtNi nanoparticles have been considered as a promising electrocatalyst for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs) owing to their high catalytic activity. However, under typical fuel cell operating conditions, Ni atoms easily dissolve into the electrolyte, resulting in degradation of the catalyst and the membrane-electrode assembly (MEA). Here, we report gallium-doped PtNi octahedral nanoparticles on a carbon support (Ga-PtNi/C). The Ga-PtNi/C shows high ORR activity, marking an 11.7-fold improvement in the mass activity (1.24 A mg_Pt^-1) and a 17.3-fold improvement in the specific activity (2.53 mA cm^-2) compared to the commercial Pt/C (0.106 A mg_Pt^-1 and 0.146 mA cm^-2). Density functional theory calculations demonstrate that addition of Ga to octahedral PtNi can cause an increase in the oxygen intermediate binding energy, leading to the enhanced catalytic activity toward ORR. In a voltage-cycling test, the Ga-PtNi/C exhibits superior stability to PtNi/C and the commercial Pt/C, maintaining the initial Ni concentration and octahedral shape of the nanoparticles. Single cell using the Ga-PtNi/C exhibits higher initial performance and durability than those using the PtNi/C and the commercial Pt/C. The majority of the Ga-PtNi nanoparticles well maintain the octahedral shape without agglomeration after the single cell durability test (30,000 cycles). This work demonstrates that the octahedral Ga-PtNi/C can be utilized as a highly active and durable ORR catalyst in practical fuel cell applications.

Low serum phosphate as an independent predictor of increased infection-related mortality in dialysis patients: A prospective multicenter cohort study

BACKGROUND

The role of mineral metabolism in mortality among dialysis patients has received increased attention, but some aspects remain unclear. The aim of the present study was to investigate the prognostic value of serum calcium and phosphate levels for all-cause mortality and cause-specific mortality in dialysis patients.

METHODS

Patients on hemodialysis and peritoneal dialysis were enrolled from a multicenter prospective cohort study in Korea (NCT00931970). The patients were divided into low, normal, and high groups according to their baseline serum calcium or phosphate levels. Cox proportional analysis and a proportional hazards model for the subdistribution of a competing risk were used to calculate hazard ratios (HRs) for the association of serum calcium and phosphate levels with all-cause and cause-specific mortality. Time-dependent values of calcium and phosphate were also evaluated to assess the effect of longitudinal change in mineral metabolism parameters on mortality types.

RESULTS

A total of 3,226 dialysis patients were followed up for a mean of 19.8 ± 8.2 months. Infection was the most common cause of death. Low serum phosphate was significantly associated with all-cause and infection-related death using time-dependent values (HR, 1.43 [95% confidence interval (CI), 1.06-1.93], P = 0.02, and HR, 1.66 [95% CI, 1.02-2.70], P = 0.04, respectively). Low serum phosphate was associated with significantly higher infection-related mortality, especially in patients older than 65 years or on dialysis more than one year or with serum albumin lower than 3.9 g/dL (HR, 2.06 [95% CI, 1.13-3.75], P = 0.02, HR, 2.19 [95% CI, 1.20-4.01], P = 0.01, and HR, 1.77 [95% CI, 1.00-3.13], P = 0.05, respectively). Multinomial logistic regression analysis results suggested that low serum albumin, creatinine, and body mass index correlated with low serum phosphate.

CONCLUSIONS

Low serum phosphate in dialysis patients was an independent risk factor for infection-related death, especially in elderly patients. Persistently low serum phosphate might be a nutritional biomarker to predict increased susceptibility to infection and in turn worse outcomes in dialysis patients.

Synthesis of Chemically Ordered Pt3Fe/C Intermetallic Electrocatalysts for Oxygen Reduction Reaction with Enhanced Activity and Durability via a Removable Carbon Coating

Recently, Pt₃M (M = Fe, Ni, Co, Cu, etc.) intermetallic compounds have been highlighted as promising candidates for oxygen reduction reaction (ORR) catalysts. In general, to form those intermetallic compounds, alloy phase nanoparticles are synthesized and then heat-treated at a high temperature. However, nanoparticles easily agglomerate during the heat treatment, resulting in a decrease in electrochemical surface area (ECSA). In this study, we synthesized Pt-Fe alloy nanoparticles and employed carbon coating to protect the nanoparticles from agglomeration during heat treatment. As a result, Pt₃Fe L1₂ structure was obtained without agglomeration of the nanoparticles; the ECSA of Pt-Fe alloy and intermetallic Pt₃Fe/C was 37.6 and 33.3 m² g_Pt^-1, respectively. Pt₃Fe/C exhibited excellent mass activity (0.454 A mg_Pt^-1) and stability with superior resistances to nanoparticle agglomeration and iron leaching. Density functional theory (DFT) calculation revealed that, owing to the higher dissolution potential of Fe atoms on the Pt₃Fe surface than those on the Pt-Fe alloy, Pt₃Fe/C had better stability than Pt-Fe/C. A single cell fabricated with Pt₃Fe/C showed higher initial performance and superior durability, compared to that with commercial Pt/C. We suggest that Pt₃M chemically ordered electrocatalysts are excellent candidates that may become the most active and durable ORR catalysts available.

Impact of dialysis modality on technique survival in end-stage renal disease patients

BACKGROUND/AIMS

This study analyzed the risk factors for technique survival in dialysis patients and compared technique survival rates between hemodialysis (HD) and peritoneal dialysis (PD) in a prospective cohort of Korean patients.

METHODS

A total of 1,042 patients undergoing dialysis from September 2008 to June 2011 were analyzed. The dialysis modality was defined as that used 90 days after commencing dialysis. Technique survival was compared between the two dialysis modalities, and the predictive risk factors were evaluated.

RESULTS

The dialysis modality was an independent risk factor predictive of technique survival. PD had a higher risk for technique failure than HD (hazard ratio [HR], 10.8; 95% confidence interval [CI], 1.9 to 62.0; p = 0.008) during a median follow-up of 11.0 months. In the PD group, a high body mass index (BMI) was an independent risk factor for technique failure (HR, 1.3; 95% CI, 1.0 to 1.8; p = 0.036). Peritonitis was the most common cause of PD technique failure. The difference in technique survival between PD and HD was more prominent in diabetic patients with a good nutritional status and in non-diabetic patients with a poor nutritional status.

CONCLUSIONS

In a prospective cohort of Korean patients with end-stage renal disease, PD was associated with a higher risk of technique failure than HD. Diabetic patients with a good nutritional status and non-diabetic patients with a poor nutritional status, as well as patients with a higher BMI, had an inferior technique survival rate with PD compared to HD.

Optimal assessment of lymph node status in gallbladder cancer

BACKGROUND

Lymph node (LN) metastasis is an important prognostic factor in gallbladder cancer (GBCA). LN status has been adopted as a critical element of staging systems. However, the influence of total lymph node count (TLNC) remains unclear. We determined the optimal minimum TLNC and compared the prognostic significance of LN status indices in GBCA.

METHODS

We retrospectively reviewed medical records of 128 patients with T2 or greater GBCA who underwent LN dissection. We analyzed overall survival (OS) and relevance of the number of metastatic LNs, ratio of metastatic LNs to retrieved LNs (LNR), and TLNC in predicting OS.

RESULTS

The median OS durations were 120, 35, and 18 months in T2, T3, and T4 GBCA. Five-year OS rates were 73%, 43%, and 0% in T2, T3, and T4 GBCA. LN status did not significantly impact OS in T2 or T4 GBCA. However, all LN indices were significantly correlated with OS in T3 GBCA. Furthermore, multivariate analysis revealed that a metastatic LN count of more than four and a TLNC of more than eight were independent prognostic factors of OS in T3 GBCA.

CONCLUSIONS

TLNC and the number of positive LNs may be more important prognostic factors than LNR in T3 GBCA. Additionally, accurate staging may not be achieved in cases of T3 GBCA if the total number of retrieved LNs is less than eight. Thus, to ensure proper staging, we recommend that surgeons harvest more than eight LNs in patients with T3 GBCA.

Deacetylation of the tumor suppressor protein PML regulates hydrogen peroxide-induced cell death

The promyelocytic leukemia protein (PML) is a tumor suppressor that is expressed at a low level in various cancers. Although post-translational modifications including SUMOylation, phosphorylation, and ubiquitination have been found to regulate the stability or activity of PML, little is known about the role of its acetylation in the control of cell survival. Here we demonstrate that acetylation of lysine 487 (K487) and SUMO1 conjugation of K490 at PML protein are mutually exclusive. We found that hydrogen peroxide (H₂O₂) promotes PML deacetylation and identified SIRT1 and SIRT5 as PML deacetylases. Both SIRT1 and SIRT5 are required for H₂O₂-mediated deacetylation of PML and accumulation of nuclear PML protein in HeLa cells. Knockdown of SIRT1 reduces the number of H₂O₂-induced PML-nuclear bodies (NBs) and increases the survival of HeLa cells. Ectopic expression of wild-type PML but not the K487R mutant rescues H₂O₂-induced cell death in SIRT1 knockdown cells. Furthermore, ectopic expression of wild-type SIRT5 but not a catalytic defective mutant can also restore H₂O₂-induced cell death in SIRT1 knockdown cells. Taken together, our findings reveal a novel regulatory mechanism in which SIRT1/SIRT5-mediated PML deacetylation plays a role in the regulation of cancer cell survival.

Successful treatment of recurrent focal segmental glomerulosclerosis with a low dose rituximab in a kidney transplant recipient

Recurrence of focal segmental glomerulosclerosis (FSGS) is a major therapeutic challenge in kidney transplantation (KT). Although intensive plasmapheresis and high-dose rituximab have been introduced to treat recurrent FSGS, the most effective dosage and regimen of rituximab have not been determined. Herein we reported the first case of successful treatment of recurrent FSGS with a low-dose rituximab. The patient showed marked proteinuria (3.5 g/d) and oliguria 2 d after KT. Two courses of plasmapheresis and immunoglobulin were applied to the patient, however, nephrotic range proteinuria persisted and creatinine level increased to 3.56 mg/dL. Five months post-transplant, the patient received injection with only one dose of rituximab 100 mg, without further plasmapheresis, which resulted in immediate reduction of serum creatinine and full remission of proteinuria during the following 18 months. This case suggested that recurrent FSGS, which frequently relapses after plasmapheresis, could be treated successfully with a low-dose rituximab even without plasmapheresis.