Quantitation and characterization of glutathionyl haemoglobin as an oxidative stress marker in chronic renal failure by mass spectrometry

OBJECTIVES: Glutathionyl haemoglobin (GS-Hb) belonging to the class of glutathionylated proteins has been investigated as a possible marker of oxidative stress in different chronic diseases. The purpose of this study was to examine whether glutathionyl haemoglobin can serve as an oxidative stress marker in non-diabetic chronic renal failure patients on different renal replacement therapies (RRT) through its quantitation, and characterization of the specific binding site of glutathione in haemoglobin molecule by mass spectrometric analysis. DESIGN AND METHODS: The study group consisted of non-diabetic chronic renal failure patients on renal replacement therapy (RRT): hemodialysis (HD), continuous ambulatory peritoneal dialysis (CAPD) and renal allograft transplant (Txp) patients. Haemoglobin samples of these subjects were analyzed by liquid chromatography electrospray ionization mass spectrometry for GS-Hb quantitation. Characterization of GS-Hb was done by tandem mass spectrometry. Levels of erythrocyte glutathione (GSH) and lipid peroxidation (as thiobarbituric acid reacting substances) were measured spectrophotometrically, while glycated haemoglobin (HbA1c) was measured by HPLC. RESULTS: GS-Hb levels were markedly elevated in the dialysis group and marginally in the transplant group as compared to the controls. GS-Hb levels correlated positively with lipid peroxidation and negatively with the erythrocyte glutathione levels in RRT groups indicating enhanced oxidative stress. De novo sequencing of the chymotryptic fragment of GS-Hb established that glutathione is attached to Cys-93 of the beta globin chain. Mass spectrometric quantitation of total glycated haemoglobin showed good agreement with HbA1c estimation by conventional HPLC method. CONCLUSIONS: Glutathionyl haemoglobin can serve as a clinical marker of oxidative stress in chronic debilitating therapies like RRT. Mass spectrometry provides a reliable analytical tool for quantitation and residue level characterization of different post-translational modifications of haemoglobin.     

A Network Modeling Approach for the Spatial Distribution and Structure of Bone Mineral Content

This study aims to develop a spatial model of bone for quantitative assessments of bone mineral density and microarchitecture. A spatially structured network model for bone microarchitecture was systematically investigated. Bone mineral-forming foci were distributed radially according to the cumulative normal distribution, and Voronoi tessellation was used to obtain edges representing bone mineral lattice. Methods to simulate X-ray images were developed. The network model recapitulated key features of real bone and contained spongy interior regions resembling trabecular bone that transitioned seamlessly to densely mineralized, compact cortical bone-like microarchitecture. Model-simulated imaging profiles were similar to patients’ X-ray images. The morphometric metrics were concordant with microcomputed tomography results for real bone. Simulations comparing normal and diseased bone of 20–30 to 70–80 year-olds demonstrated the method’s effectiveness for modeling osteoporosis. The novel spatial model may be useful for pharmacodynamic simulations of bone drugs and for modeling imaging data in clinical trials.     

Preparation of 3-hydroxyquinolines from direct oxidation of dihydroquinolinium salts

A series of functionalized 3,4-dihydroquinolinium salts were prepared from the reaction of aryldiazonium salt with alkene in a nitrile solution. Further oxidation yielding either 3-hydroxyquinoline or quinoline products was investigated. A one-pot process from aryldiazonium salts, alkenes and nitriles leading to 3-hydroxyquinolines was also developed. Furthermore, an intramolecular trapping of an N-arylnitrilium ion with a vinyl group at the ortho position leading to 2-substituted quinolines was revealed.

3-Hydroxyquinoline derivatives can be prepared by a cascade cyclization of aryldiazonium salts with nitriles and alkenes followed by oxygenation.     

Utility of impedance cardiography for the identification of short-term risk of clinical decompensation in stable patients with chronic heart failure.

OBJECTIVES: This study sought to assess the potential utility of impedance cardiography (ICG) in predicting clinical deterioration in ambulatory patients with heart failure (HF). BACKGROUND: Impedance cardiography uses changes in thoracic electrical impedance to estimate hemodynamic variables, but its ability to predict clinical events has not been evaluated. METHODS: We prospectively evaluated 212 stable patients with HF and a recent episode of clinical decompensation who underwent serial clinical evaluation and blinded ICG testing every 2 weeks for 26 weeks and were followed up for the occurrence of death or worsening HF requiring hospitalization or emergent care. RESULTS: During the study, 59 patients experienced 104 episodes of decompensated HF (16 deaths, 78 hospitalizations, and 10 emergency visits). Multivariate analysis identified 6 clinical and ICG variables that independently predicted an event within 14 days of assessment. These included three clinical variables (visual analog score, New York Heart Association functional class, and systolic blood pressure) and three ICG parameters (velocity index, thoracic fluid content index, and left ventricular ejection time). The three ICG parameters combined into a composite score was a powerful predictor of an event during the next 14 days (p = 0.0002). Visits with a high-risk composite score had 2.5 times greater likelihood and those with a low-risk score had a 70% lower likelihood of a near-term event compared with visits at intermediate risk. CONCLUSIONS: These results suggest that when performed at regular intervals in stable patients with HF with a recent episode of clinical decompensation, ICG can identify patients at increased near-term risk of recurrent decompensation.     

Molecular Evolution of Peste des Petits Ruminants Virus

Despite safe and efficacious vaccines against peste des petits ruminants virus (PPRV), this virus has emerged as the cause of a highly contagious disease with serious economic consequences for small ruminant agriculture across Asia, the Middle East, and Africa. We used complete and partial genome sequences of all 4 lineages of the virus to investigate evolutionary and epidemiologic dynamics of PPRV. A Bayesian phylogenetic analysis of all PPRV lineages mapped the time to most recent common ancestor and initial divergence of PPRV to a lineage III isolate at the beginning of 20th century. A phylogeographic approach estimated the probability for root location of an ancestral PPRV and individual lineages as being Nigeria for PPRV, Senegal for lineage I, Nigeria/Ghana for lineage II, Sudan for lineage III, and India for lineage IV. Substitution rates are critical parameters for understanding virus evolution because restrictions in genetic variation can lead to lower adaptability and pathogenicity.     

Effect of platelet-rich plasma on bone regeneration after removal of cysts and benign tumours of the jaws

Introduction

Platelets are involved in regeneration at sites of pathology, apart from their role in clotting. A preparation composed mainly of platelets (platelet-rich plasma gel) applied to sites of bony pathology, after surgical treatment of lesions, may hasten bone regeneration.

Materials and methods

An autologous platelet-rich plasma (PRP) gel was prepared using a standardized technique, without using thrombin clot accelerator, and applied to surgical site in six patients of study group. Five patients were enrolled as controls, in whom PRP gel was not used. The differences in the occurrence of radiographic changes between the study and control group at 6, 12, 18 and 24 weeks after surgery were analysed with chi-square test. Intragroup radiographic changes, i.e. within the study and control groups occurring over the 24 weeks of follow-up, were analysed with Friedman test.

Results

A trend towards more rapid healing was observed in the study group at 6, 12, 18 and 24 weeks. However, these differences between the study and control group were not statistically significant. Both the study and control group demonstrated significant healing changes over the 24 weeks of follow-up.

Conclusions

It is possible to prepare platelet-rich plasma gel without using thrombin clot accelerator. PRP, as prepared and applied to surgical sites in this study, was not observed to significantly enhance bone regeneration. All surgical sites, both in the PRP and control group, showed significant healing changes over 6 months.