Identification of urinary proteins potentially associated with diabetic kidney disease.

Diabetic nephropathy (DN) is the most common cause of chronic kidney disease. Although several parameters are used to evaluate renal damage, in many instances, there is no pathological change until damage is already advanced. Mass spectrometry-based proteomics is a novel tool to identify newer diagnostic markers. To identify urinary proteins associated with renal complications in diabetes, we collected urine samples from 10 type 2 diabetes patients each with normoalbuminuria, micro- and macro-albuminuria and compared their urinary proteome with that of 10 healthy individuals. Urinary proteins were concentrated, depleted of albumin and five other abundant plasma proteins and in-gel trypsin digested after prefractionation on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The peptides were analyzed using a nanoflow reverse phase liquid chromatography system coupled to linear trap quadrupole-Orbitrap mass spectrometer. We identified large number of proteins in each group, of which many were exclusively present in individual patient groups. A total of 53 proteins were common in all patients but were absent in the controls. The majority of the proteins were functionally binding, biologically involved in metabolic processes, and showed enrichment of alternative complement and blood coagulation pathways. In addition to identifying reported proteins such as α2-HS-glycoprotein and Vitamin D binding protein, we detected novel proteins such as CD59, extracellular matrix protein 1 (ECM1), factor H, and myoglobin in the urine of macroalbuminuria patients. ECM1 and factor H are known to influence mesangial cell proliferation, and CD59 causes microvascular damage by influencing membrane attack complex deposition, suggestive their biological relevance to DN. Thus, we have developed a proteome database where various proteins exclusively present in the patients may be further investigated for their role as stage-specific markers and possible therapeutic targets.

SPECTRUM OF SPINAL ABNORMALITIES ON MAGNETIC RESONANCE IMAGING OF PATIENTS WITH CLINICAL SUSPICION OF SPINAL LESIONS IN KANO, NIGERIA.

BACKGROUND: Magnetic resonance imaging (MRI) of the spine is a powerful tool for evaluation, assessment of severity, and follow up of diseases of the spine. It is one of the most sensitive diagnostic tests for detecting anatomic abnormalities of the spine and the adjacent structures. AIM: To determine the pattern of spinal abnormalities on MRI in Kano, Nigeria. MATERIALS AND METHOD: Patients aged between 2 and 95 years who had spinal MRI with AIRIS II TOSHIBA (0.5T) Tesla machine from January to December 2013 were reviewed. Information concerning age, gender, region and findings were recorded. RESULTS: Two hundred and sixty one patients made up of187 males and 74 females were reviewed. Their ages ranged from 2 to 95 years with the mean of 46.43 ± 15.7 years. Lumbo-sacral MRI was the most commonly performed (46.4 %) followed by cervical (44.1%), thoraco-lumbar spine (4.2%), thoracic spine (3.8%) and cervical and lumbar (1.5%). The most common indication of MRI was low back pain in 211 (80.8% ) patients followed by trauma in 36 (17.8% ) patients. About 19.6% of the MRI examinations were normal while spondylosis and moderate disc prolapse was seen in 31.5% and compressive fracture comprised 7.3% of cases. CONCLUSION: Lumbo-sacral MRI was the commonest MRI in this study and the commonest indications for MRI were low back pain and trauma while the commonest findings were spondylosis, disc prolapse, compressive fracture and spinal metastases.

Cloning and expression of Toxoplasma gondii dense granular protein 4 (GRA4) in Pichia pastoris.

GRA4 of Toxoplasma gondii has been shown to prompt IgG, IgM and IgA responses in previous studies and is thus considered one of the major immunogenic proteins from T. gondii that can be used for both diagnostics purposes and vaccine development. This study seeks to clone and express the GRA4 in Pichia pastoris, which has numerous advantages over other systems for expression of eukaryotic proteins. In order to achieve this, the gene was cloned into the pPICZα A expression vector, which was then incorporated into the P. pastoris genome via insertional integration for expression of the recombinant protein, under the AOX1 promoter. The antigen was expressed along with the prepro sequence of the α-factor of yeast so that it could be excreted out of the P. pastoris cells and obtained from the medium. Upon SDS-PAGE analysis it was found that the recombinant protein was expressed optimally as a 40 kDa protein after 96 hours of induction with 0.75% of methanol. The expressed GRA4 protein showed discrepancy in size with the calculated molecular mass. This may be attributed to the various posttranslational modifications including glycosylation and phosphorylation. Despite the difference in molecular weight, the recombinant protein was able to detect toxoplasmosis in Western blot format. The recombinant GRA4 was expressed with an intact polyhistidine-tag, which could be used for future purification of the antigen.

Association of cathepsin B gene polymorphisms with tropical calcific pancreatitis.

BACKGROUND AND AIMS: Tropical calcific pancreatitis (TCP) is a type of chronic pancreatitis unique to countries in the tropics. Mutations in pancreatic secretory trypsin inhibitor (SPINK1) rather than cationic trypsinogen (PRSS1) explain the disease in only 50% of TCP patients. As cathepsin B (CTSB) is known to activate cationic trypsinogen, we attempted to understand the role of CTSB mutations in TCP. Evidence of epistatic interaction was investigated with the previously associated N34S SPINK1 allele, a variant considered to be a modifier rather than a true susceptibility allele. SUBJECTS AND METHODS: We sequenced the coding region of CTSB gene in 51 TCP patients and 25 controls and further genotyped 89 patients and 130 controls from the same cohort for Leu26Val, C595T, T663C, and Ser53Gly polymorphisms. The positive findings observed in the earlier cohort were re-examined in an ethnically matched replication cohort comprising 166 patients and 175 controls. Appropriate statistical analyses were performed and Bonferroni correction for multiple testing was applied. RESULTS: We found a statistically significant association of the Val26 allele at Leu26Val polymorphism with an odds ratio (OR) of 2.15 (95% confidence interval (CI) 1.60-2.90 (p = 0.009)), after Bonferroni correction (corrected p value = 0.025). This significant association of Leu26Val with TCP was replicated in another cohort (OR 2.10 (95% CI 1.56-2.84); p = 0.013). Val26 allele also showed significantly higher frequency in N34S positive and N34S negative patients than in controls (p = 0.019 and 0.013, respectively). We also found significant differences in the mutant allele frequencies at Ser53Gly and C595T single nucleotide polymorphisms between N34S positive patients and controls (p = 0.008 and 0.001, respectively). Although haplotype analysis did not complement the results of allelic association, it did uncover a unique haplotype protective for TCP (p = 0.0035). CONCLUSION: Our study suggests for the first time that CTSB polymorphisms are associated with TCP. As PRSS1 mutations are absent in TCP and the N34S SPINK1 mutation is proposed to play a modifier role, these variants may be critical as a trigger for cationic trypsinogen activation.

Absence of PRSS1 mutations and association of SPINK1 trypsin inhibitor mutations in hereditary and non-hereditary chronic pancreatitis.

BACKGROUND AND AIMS: Mutations in the cationic trypsinogen (protease, serine, 1 (trypsin 1); PRSS1) gene are causally associated with recurrent acute and chronic pancreatitis. We investigated whether mutations in the PRSS1 gene are associated with hereditary and non-hereditary pancreatitis. As a modifier role has been proposed for trypsin inhibitor (serine protease inhibitor, Kazal type I; SPINK1) mutations, the role of SPINK1 mutations in these patients was also analysed. SUBJECTS AND METHODS: The coding regions of PRSS1 and SPINK1 genes were sequenced in 290 controls and 198 patients, of whom 120 were diagnosed as idiopathic (ICP), 41 as alcoholic (ACP), and 37 as hereditary pancreatitis (HP). Twenty four unaffected relatives of HP probands were also analysed and genotype-phenotype correlations and statistical analyses were performed. RESULTS: No mutations in the PRSS1 gene were detected in any of the patients, including HP patients, while the N34S mutation was observed in the SPINK1 gene in the majority of HP patients (73%). Similarly, 26.8% of ACP (11 of 41) and 32.5% (39 of 120) of ICP patients also had SPINK1 mutations. The N34S mutation was observed in both homozygous and heterozygous conditions. In comparison, only 2.76% of the control population had the N34S allele (p<0.001). The P55S mutation was observed in one ICP and one ACP patient, and in three normal individuals. Genotype-phenotype correlations did not suggest any significant difference in the age of onset, severity of disease, or pancreatic endocrine insufficiency in patients with or without mutated SPINK1 and irrespective of the allelic status of N34S SPINK1. CONCLUSIONS: Irrespective of the aetiology, mutations in the PRSS1 gene are not associated with chronic pancreatitis, including HP. In contrast, the N34S mutation in the SPINK1 gene shows a significant correlation in these patients. A comparable phenotype in terms of age of onset, diabetes mellitus, and other phenotypic features in patients with or without SPINK1 mutations and N34S homozygotes and heterozygotes suggests that there may still be involvement of other genetic or environmental factors.