Two kinds of rare light chain cast nephropathy caused by multiple myeloma: case reports and literature review.

BACKGROUND: Light chain cast nephropathy (LCCN) is the most common renal disease caused by multiple myeloma (MM). In addition to ordinary light chain protein casts, there are a few rare casts with unique shapes, including light chain amyloid casts (LCAC) and light chain crystal casts (LCCC). CASE PRESENTATIONS: Here, we report two patients. Patient 1 is a 72-year-old man who was clinically diagnosed with MM and acute kidney injury (AKI). Pathological examination of a renal biopsy revealed that there were many amyloid casts in the distal tubules that had a lightly-stained central area and a deeply-stained burr-like edge. The marginal zone of the cast was positive for Congo red staining and contained numerous amyloid fibers, as observed by electron microscopy. No systemic amyloidosis was found. The patient received 4 courses of bortezomib-based chemotherapy, and then, his MM achieved partial remission. Patient 2 is a 57-year-old man who was also clinically diagnosed with MM and AKI. Pathological examination of a renal biopsy showed that there were many crystalline casts in the distal tubules that were fully or partially composed of crystals with different shapes, including rhomboid, needle, triangle, rectangle and other geometric shapes. Congo red staining was negative. Crystals were also detected in the urine of this patient. After 9 courses of treatment with a bortezomib-based regimen, his MM obtained complete remission and his renal function returned to normal. CONCLUSIONS: LCAC and LCCC nephropathy caused by MM are two rare types of LCCN, and both have their own unique morphological manifestations. LCAC nephropathy may not be accompanied by systemic amyloidosis. The diagnosis of these two unique LCCNs must rely on renal biopsy pathology, and the discovery of urine crystals is of great significance for indicating LCCC nephropathy.

Derivation and validation of a prediction score for acute kidney injury secondary to acute myocardial infarction in Chinese patients.

BACKGROUND: Acute kidney injury (AKI) is a major complication of acute myocardial infarction(AMI), which can significantly increase mortality. This study is to analyze the related risk factors and establish a prediction score of acute kidney injury in order to take early measurement for prevention. METHODS: The medical records of 6014 hospitalized patients with AMI in Beijing Anzhen Hospital from January 2010 to December 2016 were retrospectively analyzed. These patients were randomly assigned into two cohorts: one was for the derivation of prediction score (n = 4252) and another for validation (n = 1762). The criterion for AKI was defined as an increase in serum creatinine of ≥ 0.3 mg/dL or ≥ 50% from baseline within 48 h. On the basis of odds ratio obtained from multivariate logistic regression analysis, a prediction score of acute kidney injury after AMI was built up. RESULTS: In this prediction score, risk score 1 point included hypertension history, heart rate > 100 bpm on admission, peak serum troponin I ≥ 100 µg/L, and time from admission to coronary reperfusion > 120 min; risks score 2 points included Killip classification ≥ class 3 on admission; and maximum dosage of intravenous furosemide ≥ 60 mg/d; risks score 3 points only included shock during hospitalization. In addition, when baseline estimated glomerular filtration rate (eGFR) was less than 90 ml/min·1.73 m2, every 10 ml/min·1.73 m2 reduction of eGFR increased risk score 1 point. Youden index showed that the best cut-off value for prediction of AKI was 3 points with a sensitivity of 71.1% and specificity 74.2%. The datasets of derivation and validation both displayed adequate discrimination (an area under the ROC curve, 0.79 and 0.81, respectively) and satisfactory calibration (Hosmer-Lemeshow statistic test, P = 0.63 and P = 0.60, respectively). CONCLUSIONS: In conclusion, a prediction score for AKI secondary to AMI in Chinese patients was established, which may help to prevent AKI early.

[Application of Immunohistochemistry and Immunofluorescence Staining in Detection of Phospholipase A2 Receptor on Paraffin Section of Renal Biopsy Tissue].

OBJECTIVE: To evaluate the application of immunohistochemistry and fluorescence staining method in the detection of phospholipase A2 receptor (PLA2R) on paraffin section of renal biopsy tissue,and to find an accurate and fast method for the detection of PLA2R in renal tissue. METHODS: The PLA2R of 193 cases were detected by immunohistochemical staining,and the antigen was repaired by the method of high pressure cooker (HPC) hot repair plus trypsin repair. The 193 samples including 139 cases of idiopathic membranous nephropathy (IMN), 15 cases of membranous lupus nephritis, 8 cases of hepatitis B virus associated membranous nephropathy, 18 cases of IgA nephropathy, and 13 cases of minimal change diseases. To compare the dyeing effects, 22 paraffin sections of renal biopsy tissue of IMN cases with positive PLA2R were stained by using 4 different. METHODS: of antigen repairing,which included HPC hot repair, HPC hot repair plus trypsin repair, water bath heat repair, and water bath heat repair plus trypsin repair. To compare the dyeing effects, 15 paraffin sections of renal biopsy tissue of IMN cases with positive PLA2R were stained by using 3 different. METHODS: of antigen repairing,which included water bath heat repair plus trypsin repair, protease K digestion repair, and pepsin digestion repair. RESULTS: In 193 cases, the positive rate of PLA2R in IMN cases was 90.6% (126/139), and the other 54 patients without IMN were negative. Twenty-two IMN patients were positive for PLA2R by using the HPC heat repair plus trypsin repaire or the water bath heat repair plus trypsin repair;while only a few cases of 22 IMN cases were positive by using the HPC hot repair alone or water bath heat repair alone. Fifteen IMN patients were positive for PLA2R by using water bath heat repair plus trypsin repair,protease K digestion repair,and pepsin digestion repair, but the distribution of positive deposits and the background were different. CONCLUSIONS: PLA2R immunohistochemical staining can effectively identify IMN and secondary MN. For immunohistochemical staining and immunofluorescence staining, the preferred method of antigen repair is water bath heat repair plus trypsin repair.

Derivation and validation of a risk score for contrast-induced nephropathy after cardiac catheterization in Chinese patients.

BACKGROUND: To derive and validate a risk score for prediction of contrast-induced nephropathy (CIN) in the Chinese patients undergoing cardiac catheterization. METHODS: The hospital medical records of 3945 patients undergoing coronary angiography or percutaneous coronary intervention were reviewed. Patients were randomly assigned into two cohorts: one was for derivation of risk score (n = 2764) and another for validation (n = 1181). The CIN was defined as an increase of serum creatinine level ≥44.2 µmol/L or ≥25 % and beyond its upper limit of normal value within 72 h following the procedure. On the basis of the odds ratio obtained from multivariate logistic regression, risk score of CIN was built up. The discrimination of the risk score was assessed using the area under the receiver operating characteristic curve and the calibration was assessed using the Hosmer-Lemeshow goodness-of-fit test. RESULTS: The incidences of CIN in the derivation and validation cohorts were 4.6 and 4.2 %, respectively. Independent predictors included age >60 years, hypertension, acute myocardial infarction, heart failure, use of intra-aortic balloon pump, decreased glomerular filtration rate and contrast volume >100 mL. The incidence of CIN was increased with increment of risk score. Both the derivation and validation cohorts showed adequate discrimination (an area under the ROC curve, 0.76 and 0.71, respectively) and good calibration (Hosmer-Lemeshow statistic test, P = 0.50 and P = 0.54, respectively). CONCLUSION: A simple risk score for prediction of CIN development after cardiac catheterization in Chinese patients was built up by this study. Use of this risk score may help clinicians to perform early preventative strategies to minimize the risk of CIN.

Derivation and validation of a prediction score for acute kidney injury in patients hospitalized with acute heart failure in a Chinese cohort.

AIMS: Acute kidney injury (AKI) is a common complication among patients hospitalized for acute heart failure (AHF), and is associated with increased mortality. The goal of this study was to derive and validate a prediction score for AKI in AHF patients. METHODS: The hospital medical records of 1709 patients with AHF were reviewed. AKI was defined as an increase in serum creatinine (SCr) of ≥26.4 µmol/L or ≥50% within 48 h. A multivariate logistic regression analysis was undertaken to develop a new prediction score. The area under the receiver operating characteristic (ROC) curve and the Hosmer-Lemeshow goodness-of-fit statistic test were calculated to assess the discrimination and calibration of the prediction score, respectively. RESULTS: Acute kidney injury developed in 32.2% of patients with AHF. Factors independently associated with the risk of AKI included: ≥70 years of age, ≥3 previous hospital admissions for AHF, systolic blood pressure <90 mmHg, serum sodium <130 mmol/L, heart functional class IV, proteinuria, SCr ≥104 µmol/L and intravenous furosemide dose ≥80 mg/day. A prediction score for AKI was derived based on the ß coefficients of each risk factor. Patients with ≥8 points would be considered at high risk for development of AKI (55.1% incidence vs 18% in those with <8 points, P < 0.001). Both the derived and validated datasets showed adequate discrimination (area under ROC curve was 0.76 in both datasets) and calibration (Hosmer-Lemeshow statistic test, P = 0.98 and 0.13, respectively). CONCLUSION: The newly derived and validated clinical prediction score may effectively predict AKI in the patients hospitalized with AHF.

JNK-dependent AP-1 activation is required for aristolochic acid-induced TGF-ß1 synthesis in human renal proximal epithelial cells.

Chronic aristolochic acid nephropathy (CAAN) is a chronic and progressive tubulointerstitial nephropathy characterized by extensive interstitial fibrosis. Aristolochic acid (AA) could induce overexpression of transforming growth factor-ß1 (TGF-ß1) in a human renal proximal tubule epithelial cells line (HKC), which has been implicated in the pathogenesis of CAAN. The present studies in HKC cells showed 1) AA could activate JNK in time- and dose-dependent manners and JNK inhibitor SP600125 could inhibit AA-induced TGF-ß1 promoter activity and TGF-ß1 synthesis; 2) AA-induced JNK activation and TGF-ß1 synthesis were significantly inhibited by kinase-inactive mutants of MEKK4, MKK4, or MKK7; 3) AA could upregulate luciferase activity derived by a wild-type TGF-ß1 promoter, but not by an AP-1 binding-deficient TGF-ß1 promoter; and 4) AA could upregulate expression of c-Fos, phospho-c-Jun, and phospho-ATF2. The above data suggest AA-induced TGF-ß1 overexpression in HKC cells may be mainly mediated by the JNK signaling pathway. Both the upstream kinases of JNK including MEKK4, MKK4, and MKK7, and the downstream transcription factor of JNK, AP-1, may also participate in this process.

Determination of normal value of glomerular size in Chinese adults by different measurement methods.

AIM: Identification of glomerulomegaly is a prerequisite for diagnosis of obesity-related glomerulopathy, so measurement of glomerular size is of critical importance. METHODS: A total 100 cases pathologically diagnosed as minor glomerular abnormalities or thin basement membrane nephropathy with normal body mass index and blood glucose level were selected as the normal value measurement group of glomerular size. The mean value of diameters of capillary tuft on the glomerular maximum profile was determined using the direct method and indirect method with the Motic Med 6.0 digital medical image analysis system. Meanwhile, 80 cases of different glomerular disease with normal body mass index and blood glucose level were also collected. Their glomerular diameters were measured and compared with those in the normal value measurement group. RESULTS: The measurement results showed that gender and age had no effects on glomerular diameter. The normal value ranges of the diameter on glomerular maximum profile were as follows. (i) Pole-containing glomerulus (the glomerulus with vascular pole or/and urinary pole): direct method, 101.3-184.9 µm; indirect method, 100.3-183.5 µm. (ii) Pole-containing glomerulus plus non-pole glomerulus (the glomerulus without poles, the maximum profile of which was larger than that in the smallest pole-containing glomerulus): direct method, 108.3-185.9 µm; indirect method, 107.4-185.4 µm. The glomerular diameters of the 80 cases with different glomerular disease were all within the aforementioned normal value ranges. CONCLUSIONS: Both methods used in the present study are feasible to measure the glomerular diameter and the normal value range of glomerular diameter in Chinese adults is established.

Colorimetric detection of Fe3+ ions using pyrophosphate functionalized gold nanoparticles.

A sensitive, selective colorimetric Fe(3+) detection method has been developed by using pyrophosphate functionalized gold nanoparticles (P(2)O(7)(4-)-AuNPs). Gold nanoparticles were prepared by reducing HAuCl(4) with sodium borohydride, in the presence of Na(4)P(2)O(7). IR spectra suggested that pyrophosphates were capped on the surface of the gold nanoparticles. Aggregation of P(2)O(7)(4-)-AuNPs was induced immediately in the presence of Fe(3+) ions, yielding a color change from pink to violet. This Fe(3+)-induced aggregation of P(2)O(7)(4-)-AuNPs was monitored using first the naked eye and then UV-vis spectroscopy with a detection limit of 5.6 µM. The P(2)O(7)(4-)-AuNPs bound by Fe(3+) showed excellent selectivity compared to other metal ions (Ca(2+), Cd(2+), Co(2+), Fe(2+), Hg(2+), K(+), Mg(2+), Mn(2+), Na(+), Ni(2+), Pb(2+), and Zn(2+)). The best detection of Fe(3+) was achieved in a pH range from 3 to 9. In addition, the P(2)O(7)(4-)-AuNPs were also used to detect Fe(3+) in lake water samples, with low interference.

A case report of varicella-zoster virus infection associated glomerulonephritis and encephalitis.

15-year-old boy was admitted with nephritic and nephrotic syndrome, renal dysfunction and decreased serum C3, who suffered from varicella for two months. His renal histopathology revealed endocapillary proliferative glomerulonephritis with podocytes proliferation and severe tubular injury by light microscopy. Direct immunofluorescence showed global granular deposition of IgG, IgA, IgM, C3, C1q and fibrinogen in mesangium and along glomerular capillary wall. Electron microscopic examination showed electron-dense deposits in multiple sites of glomeruli. Furthermore, specific serum IgM antibodies against varicella-zoster virus (VZV) were detected. VZV antigen and mRNA were demonstrated in glomerular and tubular epithelial cells by immunohistochemical staining and in-situ hybridization. Virus particles and virus inclusions were identified by electron microscopy and special staining (Methylene Blue and Eosion staining or Mann staining). The patient also experienced epileptic episodes and his brain MRI and electroencephalogram indicated herpes encephalitis with secondary epilepsy. Therefore, the diagnosis of VZV-associated glomerulonephritis and encephalitis was established. This is the first case of VZV-associated glomerulonephritis with renal histopathological evidence using in situ hybridization technique.

[Expression and regulation of adiponectin in human renal glomerular endothelial cells].

OBJECTIVE: To investigate the expression and regulation of adiponectin in human renal glomerular endothelial cells (HRGEC). METHOD: The adiponectin expression in human renal tissue was examined with immunohistochemistry assay, and the adiponectin mRNA and protein expression of HRGEC was confirmed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot, respectively. PCR product was sequenced. To investigate the regulation action of TNF-alpha, the adiponectin produced by HRGEC was semi-quantitatively determined with real-time PCR in mRNA level and quantitatively measured with dissociation enhanced lanthanide fluorescence immunoassay (DELFIA) in protein level, respectively. RESULTS: (1) Positive adiponectin staining was observed on human glomerular capillary wall with immunohistochemistry assay. (2) Adiponectin mRNA expression in HRGEC was detected by RT-PCR, and the DNA sequence of this PCR product is consistent with adiponectin DNA sequence in Gene Bank. Adiponectin protein was also found in the supernatant of cultured HRGEC by Western blot. (3) Compared with control groups, the adiponectin mRNA expression in HRGEC determined by real-time PCR was significantly up-regulated after 250 IU/ml and 500 IU/ml TNF-alpha stimulation for 24 h (P < 0.05 and P < 0.01), and the adiponectin protein levels in culture supernatant measured by DELFIA were also significantly increased in these two groups (P < 0.05 and P < 0.01). (4) Compared with control groups, the adiponectin mRNA expression in HRGEC was significantly up-regulated after 500 IU/ml TNF-alpha stimulation for 6 h, 12 h and 24 h (P < 0.05, P < 0.05 and P < 0.01), and the adiponectin protein levels in culture supernatant were also significantly increased after stimulation for 24 h and 48 h (P < 0.01). CONCLUSIONS: HRGEC is able to synthesize adiponectin, and TNF-alpha can up-regulate its mRNA and protein expression.

[Establishment of a new rat model of chronic cyclosporine A nephrotoxicity].

OBJECTIVE: To establish a new rat model of chronic cyclosporine A nephrotoxicity and explore its features. METHODS: Totally 24 male SD rats were equally randomized divided into 3 groups: sham-adrenalectomized (sham-ADX) group, ADX group and ADX plus cyclosporine A (CsA) group. Rats in ADX and CsA group first underwent adrenalectomy, followed by the administration of placebo or dexamethasone, respectively. Rats in sham-ADX group received sham adrenalectomy and distilled water as control. Six weeks later, all rats were sacrificed and the following indicators were evaluated: urine protein excretion, creatinine clearance, aldosterone level in serum and urine, aldosterone level and its synthase CYP11B2 gene expression in kidney, serum natrium and potassium, urine natrium and potassium excretion, and tubulointerstitial fibrosis by masson trichrome stain. RESULTS: In ADX and CsA group, serum and urine aldosterone were undetectable on the second post-operative day, with other observations including natriuresis, hyponatremia, decreased urine potassium excretion, and hyperpotassemia, suggesting that adrenals were removed intact and the adrenalectomy was successful. Rats in CsA group showed increased urine protein, decreased creatinine clearance and tubulointerstitial fibrosis, suggesting that a model of chronic CsA nephrotoxicity was successfully established. At the endpoint, serum potassium, serum aldosterone, urine potassium and urine aldosterone excretion partially retrieved. Natrium in serum and urine was not significant different between ADX group/CsA group and sham-ADX group. Local renal aldosterone and its gene expression were remarkably upregulated. CONCLUSIONS: We successfully established a new rat model of chronic CsA nephrotoxicity by adrenalectomy without low sodium diet. After adrenalectomy, local renal aldosterone in kidney may compensate for circulatory aldosterone deficit to maintain electrolyte balance.

SMRT sequencing revealed to be an effective method for ADTKD-MUC1 diagnosis through follow-up analysis of a Chinese family.

We reported a large Chinese family diagnosed with autosomal dominant tubulointerstitial kidney disease caused by MUC1 mutation (ADTKD-MUC1). Cytosine duplication within a string of 7 cytosines in the variable-number tandem repeats (VNTR) region of the MUC1 gene was detected by long-read single-molecule real-time (SMRT) sequencing. MUC1 frameshift protein (MUC1fs) was found to be expressed in renal tubules and urinary exfoliated cells by pathological examination. The family, which consisted of 5 generations including 137 individuals, was followed for 5 years. Genetic testing was performed in thirty-four individuals, 17 of whom carried MUC1 mutations. The ADTKD-MUC1-affected individuals had an elevated incidence of hyperuricaemia without gout attack. Within five years, higher baseline levels of urinary α1-microglobulin were detected in affected individuals with rapidly progressing renal failure than in affected individuals with stable renal function, and the increases manifested even before increases in serum creatinine. This study demonstrates that SMRT sequencing is an effective method for the identification of MUC1 mutations. The pathological examination of MUC1fs expression in renal tissue and urinary exfoliated cells can contribute to early screening of family members suspected to be affected. It is suggested that affected individuals with elevated urinary α1-microglobulin levels should be closely monitored for renal function.

[Organic anion transporter system mediates the transport of aristolochic acid in tubular epithelial cells].

OBJECTIVE: To investigate whether aristolochic acid can be transported into human kidney proximal tubular cell (HKC) and its potential mechanism. METHODS: Intracellular aristolochic acid was measured by liquid chromatography-tandem mass spectrometry. The release of lactate dehydrogenase (LDH) induced by aristolochic acid in the presence of organic anion transporter inhibitor (probenecid) or organic cation transporter inhibitor (tetraethylammonium) was evaluated. The effects of probenecid on aristolochic acid induced connective tissue growth factor (CTGF) mRNA and protein expression were also examined by real time polymerase chain reaction and Western blot, respectively. RESULTS: Aristolochic acid was detected in the suspension of the denatured HKC after incubation with aristolochic acid sodium salt. The release of LDH from HKC, which was induced by 60 mg/L aristolochic acid sodium salt, was significantly inhibited by 1 mmol/L probenecid (P < 0.01), but not by 1 mmol/L tetraethylammonium. The increased CTGF mRNA and protein expression in HKC stimulated by 40 mg/L aristolochic acid sodium salt was significantly down-regulated by 1 mmol/L probenecid (P < 0.05), with an inhibition rate of 16% and 21%, respectively. CONCLUSION: Aristolochic acid can be transported into HKC by organic anion transport system, and then exerts its biological effects.

[Effects of Hirsutella sinensis on TGF-beta1 and Snail expressions and transdifferentiation of tubular epithelial-myofibroblast in renal tissue of rats with chronic aristolochic acid nephropathy].

OBJECTIVE: To investigate the antagonizing effect of Hirsutella sinensis (HS) on renal tubular epithelial-myofibroblast transdifferentiation (TEMT) and its possible pathogenic mechanism in rats with chronic aristolochic acid nephropathy (CAAN). METHODS: Eighteen male Sprague-Dawley rats were equally divided into 3 groups, the model (M) group, the intervention (I) group and the control (C) group. The 24 h urinary protein (UP) in rats was measured before intervention and at the end of the 1st, 4th, 8th, and 12th week, and creatinine clearance rate (CCr) was measured before intervention and at the end of the 12th week respectively. All rats were sacrificed at the end of the 12th week, their kidney was taken for examining the degree of fibrosis in renal interstitial with Masson's stain and determining mRNA and protein expressions of transforming growth factor-beta1 (TGF-beta1), Snail, alpha-smooth muscle actin (alpha-SMA) and cytokeratin in renal tissue by Real-time RT-PCR and immunohistochemistry staining, respectively. RESULTS: Compared with the C group, CCr was significantly lower, while 24 h UP was higher; the relative area of interstitial fibrosis was significantly larger in the M group; besides, the mRNA and protein expressions of TGF-beta1, Snail and alpha-SMA were significantly up-regulated (P < 0.01 or P < 0.05), and those of cytokeratin were significantly down-regulated (P < 0.01) in renal tissue of the M group. While in the I group, all the above-mentioned abnormalities were restored to some extent (P < 0.05) and showed significant difference (all P < 0.05) as compared with those in the M group. CONCLUSION: HS can downregulate TGF-beta1 and Snail expressions in renal tissue, antagonize TEMT and renal interstitial fibrosis, and improve renal function in CAAN rats.

Cryoglobulinemic vasculitis and glomerulonephritis: concerns in clinical practice.

OBJECTIVE: Cryoglobulinemia often causes systemic vasculitis, thereby damaging to skin and internal organs including kidneys, even life-threatening. This review aimed to introduce the advances in understanding, detection, and treatment of this disease in recent years, with a particular concern to clinical practice. DATA SOURCES: All the data in this review were from the English or Chinese literature in the PubMed and China National Knowledge Infrastructure databases as of March 2019. STUDY SELECTION: This review selected important original articles, meaningful reviews, and some reports on cryoglobulinemia published in recent years and in history, as well as the guidelines for treatment of underlying diseases which lead to cryoglobulinemia. RESULTS: Diagnosis of cryoglobulinemia relies on serum cryoglobulin test, in which to ensure that the blood sample temperature is not less than 37°C in the entire pre-analysis phase is the key to avoid false negative results. Cryoglobulinemic vasculitis (Cryo Vas), including cryoglobulinemic glomerulonephritis (Cryo GN), usually occurs in types II and III mixed cryoglobulinemia, and can also be seen in type I cryoglobulinemia caused by monoclonal IgG3 or IgG1. Skin purpura, positive serum rheumatoid factor, and decreased serum levels of C4 and C3 are important clues for prompting types II and III Cryo Vas. Renal biopsy is an important means for diagnosis of Cryo GN, while membranous proliferative GN is the most common pathological type of Cryo GN. In recent years, great advances have been made in the treatment of Cryo Vas and its underlying diseases, and this review has briefly introduced these advances. CONCLUSIONS: Laboratory examinations of serum cryoglobulins urgently need standardization. The recent advances in the diagnosis and treatment of Cryo Vas and GN need to be popularized among the clinicians in related disciplines.

IgG4-related sialadenitis complicated with type III mixed cryoglobulinemia: A case report.

RATIONALE: IgG4-related disease (IgG4-RD) is a systemic autoimmune disease and mixed cryoglobulinemia may be caused by autoimmune diseases. However, so far only 1 case of IgG4-RD complicated with mixed cryoglobulinemia is reported. Our case further confirms the close relationship between these 2 diseases. PATIENT CONCERNS: A 55-year-old female was admitted because of dry mouth and teeth falling off. DIAGNOSES: The patient was diagnosed as IgG4-related sialadenitis (IgG4-RS) complicated with type III mixed cryoglobulinemia. IgG4-RS was confirmed by elevated serum IgG4 levels and diffuse IgG4 plasmocyte infiltration and storiform fibrosis in the interstitium of labial gland. Type III mixed cryoglobulinemia was confirmed by positive serum cryoglobulins and no monoclonal immunoglobulin in serum and urine. INTERVENTIONS AND OUTCOMES: After treatment with prednisone and cyclophosphamide, serum cryoglobulins rapidly turned negative with the remission of IgG4-RS. LESSONS: Type III mixed cryoglobulinemia can be caused by IgG4-RS, and the underlying mechanisms need to be further explored.

Significance of the conserved Tyr352 and Asp380 residues in the catalytic activity of Bacillus stearothermophilus aminopeptidase II as evaluated by site-directed mutagenesis.

The importance of the conserved Tyr352 and Asp380 residues of Bacillus stearothermophilus aminopeptidase II (AP-II) was investigated by site-directed mutagenesis. The wild-type and mutant enzymes were expressed in recombinant Escherichia coli M15 cells and the 45-kD proteins were purified from the cell-free extracts by Ni(2+)-NTA resin. The specific activity for Tyr352 and Asp380 replacements was decreased by more than 3.5-fold. Detailed analysis of the kinetic consequences in the mutant proteins revealed that the K (m) values were increased 1.9- to 2.6-fold with respect to wild-type enzyme. Catalytic efficiencies (k (cat)/K (m)) of mutant proteins were between 3.5- and 31-fold lower than the corresponding value of the wild-type enzyme. Tryptophan emission fluorescence and circular dichroism spectra were nearly identical for wild-type and mutant enzymes. These results indicate that residues Tyr352 and Asp380 are essential for the proper function of AP-II.

[Synthesis and mass spectrometric analysis of aristolochic acid-deoxyguanosine adducts].

To synthesize aristolochic acid (AA)-2'-deoxyguanosine 5'-monophosphate (dGp) adducts in vitro and develop a novel method for the characterization of the adducts using multiple mass spectrometric techniques. AA was incubated with dGp in vitro using either enzymatic activation (by xanthine oxidase) or chemical activation (by zinc) to synthesize AA-dGp adducts, and the reaction conditions were optimized. Crude extracts were analyzed by techniques of liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-MS/MS) and high accuracy mass data and isotope pattern of super high resolution Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICRMS). The quasi-molecular ion peaks of the AA-dGp adducts were obtained in the negative ion mode. Analysis by electrospray ionization/tandem mass spectrometry (ESI-MS/MS) provided useful structural information about AA-dGp adducts. AA can bind covalently to the exocyclic amino group of deoxyguanosine to form AA-dGp adducts. MS analysis is a powerful tool to detect and identify AA-dGp adducts simply, rapidly and accurately.

Purinergic 2X7 Receptor is Involved in the Podocyte Damage of Obesity-Related Glomerulopathy via Activating Nucleotide-Binding and Oligomerization Domain-Like Receptor Protein 3 Inflammasome.

BACKGROUND: The nucleotide-binding and oligomerization domain-like receptor protein 3 (NLRP3) inflammasome composed of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), and caspase-1 is engaged in the inflammatory response of many kidney diseases and can be activated by purinergic 2X7 receptor (P2X7R). This study was conducted to explore whether P2X7R plays a pathogenic role in the podocyte damage of obesity-related glomerulopathy (ORG) and whether this role is mediated by the activation of NLRP3 inflammasome. METHODS: A mouse model of ORG was established by high-fat diet feeding. The conditionally immortalized mouse podocytes were cultured with leptin or with leptin and P2X7R antagonist (KN-62 or A438079). The mRNA and protein expression of the P2X7R and NLRP3 inflammasome components including NLRP3, ASC, and caspase-1, as well as the podocyte-associated molecules including nephrin, podocin, and desmin in mouse renal cortex or cultured mouse podocytes were tested by real-time-polymerase chain reaction and Western blot analysis, respectively. RESULTS: The significantly upregulated expression of P2X7R and NLRP3 inflammasome components and the NLRP3 inflammasome activation were observed in the renal cortex (in fact their location in podocytes was proved by confocal microscopy) of ORG mice in vivo, which were accompanied with the morphological changes of podocyte damage and the expression changes of podocyte-associated molecules. Similar changes in the expression of P2X7R and NLRP3 inflammasome components as well as in the expression of podocyte-associated molecules were also observed in the cultured podocyte studies treated by leptin in vitro, and all of the above changes were significantly attenuated by the P2X7R antagonist KN-62 or A438079. CONCLUSIONS: P2X7R could trigger the activation of NLRP3 inflammasome, and the activated P2X7R/NLRP3 inflammasome in podocytes might be involved in the podocyte damage of ORG.