Protonated and deprotonated vanadyl imidazole tartrates for the mimics of the vanadium coordination in the FeV-cofactor of V-nitrogenase.

Chiral imidazole-based oxidovanadium tartrates (H2im)2[Δ,Λ-VIV2O2(R,R-H2tart)(R,R-tart)(Him)2]·Him (1, H4tart = tartaric acid, Him = imidazole) and [Λ,Λ-VIV2O2(R,R-tart)(Him)6]·4H2O (2) and their corresponding enantiomers (H2im)2[Λ,Δ-VIV2O2(S,S-H2tart)(S,S-tart)(Him)2]·Him (3) and [Δ,Δ-VIV2O2(S,S-tart)(Him)6]·4H2O (4) were obtained in alkaline solutions. Interestingly, the tartrates chelate with vanadium bidentately through α-alkoxy/α-hydroxy and α-carboxy groups and imidazole coordinates monodentately through nitrogen atom. It is worth noting that complexes 1 and 3 contain both protonated α-hydroxy and deprotonated α-alkoxy groups simultaneously, which have short V-Oα-alkoxy distances [1.976(4)av Å in 1-4] and long V-Oα-hydroxy distances [2.237(3)av Å in 1 and 2.230(2)av Å in 3]. There is an interesting strong intramolecular hydrogen bond [O(11)⋯O(1) 2.731(5) Å] between the two parts in 1 and 3. The protonated V-O distances are closer to the average bond distance in reported FeV-cofactors (FeV-cos, V-Oα-alkoxy 2.156av Å) in VFe proteins, which corresponds to the feasible protonation of coordinated α-hydroxy in R-homocitrate in V-nitrogenase, showing the homocitrate in the mechanistic model for nitrogen reduction as a secondary proton donor. Furthermore, vibrational circular dichroism (VCD) and IR spectra of 1-4 pointed out the disparity between the characteristic vibrations of the C-O and C-OH groups clearly. EPR experiment and theoretical calculations support +4 oxidation states for vanadium in 1-4. Solution 13C {1H} NMR spectra and CV analyses exhibited the solution properties for 1 and 2, respectively, which indicates that there should be a rapid exchange equilibrium between the protonated and deprotonated species in solutions.

Bond-valence analyses of the crystal structures of FeMo/V cofactors in FeMo/V proteins.

The bond-valence method has been used for valence calculations of FeMo/V cofactors in FeMo/V proteins using 51 crystallographic data sets of FeMo/V proteins from the Protein Data Bank. The calculations show molybdenum(III) to be present in MoFe7S9C(Cys)(HHis)[R-(H)homocit] (where H4homocit is homocitric acid, HCys is cysteine and HHis is histidine) in FeMo cofactors, while vanadium(III) with a more reduced iron complement is obtained for FeV cofactors. Using an error analysis of the calculated valences, it was found that in FeMo cofactors Fe1, Fe6 and Fe7 can be unambiguously assigned as iron(III), while Fe2, Fe3, Fe4 and Fe5 show different degrees of mixed valences for the individual Fe atoms. For the FeV cofactors in PDB entry 5n6y, Fe4, Fe5 and Fe6 correspond to iron(II), iron(II) and iron(III), respectively, while Fe1, Fe2, Fe3 and Fe7 exhibit strongly mixed valences. Special situations such as CO-bound and selenium-substituted FeMo cofactors and O(N)H-bridged FeV cofactors are also discussed and suggest rearrangement of the electron configuration on the substitution of the bridging S atoms.

[Clinical and pathological features in IgA nephropathy with IgG deposition in the glomerular mesangial area].

OBJECTIVE: To investigate the relationship between the clinical and pathological findings in IgA nephropathy with or without IgG deposition in the glomerular mesangial area. METHODS: The data were collected from 122 patients with a diagnosis of IgA nephropathy by renal biopsy in the Third Affiliated Hospital of Southern Medical University between November, 2009 and February, 2016. All the samples were examined by light microscopy, immunofluorescence and electron microscopy. According to the results of immunofluorescence assay, the patients were divided into IgA group (n=63) and IgA-IgG group (n=59). The pathological classification of IgA nephropathy was analyzed according to Oxford classification and Lee's classification. The clinical and pathological findings were compared between the two groups. RESULTS: Compared with the patients with IgA nephropathy but without IgG deposition, patients with IgA nephropathy with IgG deposition had higher serum creatinine, higher 24-h urine protein, higher blood uric acid, higher triglyceride levels (P<0.05) and lower eGFR (P<0.05); more of these patients were in Lee's grade IV-V, had renal tubular atrophy and/or interstitial fibrosis, and had MEST scores more than 3 (P<0.05). CONCLUSION: Patients with IgA nephropathy with IgG deposition in the glomerular mesangial have severer clinical symptoms and more serious pathological changes. Measures should be taken to control IgG deposition in patients with IgA nephropathy to delay the progress of the disease.

[Association of waist-to-hip ratio with chronic kidney disease in non-diabetic subjects].

OBJECTIVE: To explore the relationship between waist-to-hip ratio (WHR) and chronic kidney disease (CKD) in non-diabetic subjects and compare the difference between male and female subjects. METHODS: We performed a cross-sectional survey among 2142 community-based southern Chinese participants without diabetes from June to October 2012. We divided all the participants into 4 groups according to the gender-specific quartiles of WHR. Logistic regression models were used to explore the associations of WHR with CKD in these subjects. RESULTS: In the unadjusted model, WHR was significantly associated with CKD in women (OR=7.29, 95% CI: 3.56-16.32, P<0.001), and the association was still significant (OR=6.13, 95% CI: 2.56-15.20, P=0.003 ) after adjustment for the potential confounders (including age, history of hypertension, coronary heart disease, current smoker, physical inactivity, education level, systolic blood pressure, diastolic blood pressure, serum triglyceride, serum high density lipoprotein, blood glucose, and BMI). The odds ratio (OR) for having CKD in the highest versus lowest quartile of WHR levels was 2.44 (95% CI: 0.98-4.97, P=0.103) in men in the unadjusted model. CONCLUSION: WHR levels are associated with CKD in non-diabetic women but not in non-diabetic male subjects.

[Detection of PLA2R1 in renal biopsy specimens of patients with idiopathic membranous nephropathy].

OBJECTIVE: To investigate the prevalence of PLA2R1 in renal biopsy specimens of patients with idiopathic membranous nephropathy (IMN) and explore the relationship between PLA2R1 and IMN. METHODS: A total of 108 adult patients with biopsy-proved glomerular diseases were enrolled in this study, including 41 with IMN, 2 with hepatitis B-associated membranous nephropathy, 8 with V lupus nephritis, 27 with IgA nephropathy, 19 with minimal change nephropathy, 5 with mild mesangial proliferative glomerulonephritis, and 6 with focal segmental glomeruloselerosis (FSGS). Indirect immunofluorescence assay was used to detect PLA2R1 in the biopsy specimens and the clinical variables of the IMN patients were analyzed. RESULTS: In 35 of the 41 (85.37%) patients with IMN, PLA2R1 was detected with a fine granular pattern in the subepithelial deposits along the glomerular capillary loops. PLA2R1 antigen was not detected in patients with other glomerulopathies. No significant differences were found in age, serum creatinine, serum albumin, or 24-h urinary protein level between PLA2R1-positive and negative patients with IMN (P>0.05). CONCLUSION: According to our results, 85.37% of adult patients with biopsy-proven IMN are positive for PLA2R1 antigen, which, however, does not contribute to variations of the patients' clinical manifestations.