Molecular interaction of 4-amino-N’-(benzoyloxy)-N-(2,4- dimethylphenyl)-1,2,5-oxadiazole-3-carboximidamide with the methotrexate binding site of human DHFR, and its implication in rheumatoid arthritis

Purpose: To identify an improved lead molecule for the human dihydrofolate reductase (DHFR) inhibition that ‘sits’ in the same binding cavity as methotrexate by high throughput computationalscreening.Methods: The 3-D structure of the DHFR binding site was examined using ‘CASTp3.0’. Structure based in silico screening of about 5 million drug candidates housed in the MCULE database was performed. The obtained molecule-hits were ranked in accordance with their VINA scores, made to pass through drug-likeness filters, ΔG cut-off criterion, toxicity-checker and finally ‘zero RO5 criterion’.Results: The ‘top molecule’, namely, 4-amino-N'-(benzoyloxy)-N-(2,4-dimethylphenyl)-1,2,5-oxadiazole- 3-carboximidamide, displayed robust binding with human DHFR through 21 amino acid residues (ΔG = - 9.6 kcal/mol) while 10 of these residues were the same as those displayed by ‘methotrexate binding interactions’. It passed through relevant drug screening filters including the ‘Toxicity Checker’.Conclusion: This research work describes the molecular interaction of human DHFR with an improved lead molecule named, 4-amino- N’-(benzoyloxy)-N-(2,4-dimethylphenyl)-1,2,5-oxadiazole-3- carboximidamide, with a ΔG of -9.6 kcal/mol, thus satisfying adequate ADME features for further in vitro and in vivo validation in the context of rheumatoid arthritis. Keywords: Dihydrofolate reductase, In silico screening, Methotrexate, Rheumatoid arthritis, DHF

Identification of a putative anti-rheumatoid arthritis molecule by virtual screening

Purpose: To propose an improved chemical skeleton whose scaffolds could be used for the design of future thymidylate synthase (TS)-inhibitors against rheumatoid arthritis. Methods: The drug discovery platform, ‘MCULE’, was employed for inhibitor-screening. The ‘methotrexate-interaction site’ in the crystal (PDB ID 5X66) was used as a target. One ‘RO5 violation’ was permitted. A maximum of ‘10 rotatable bonds’ and ‘100 diverse molecules’ were also allowed in the protocol. The ‘threshold similarity cut off’ was 0.7. The input values describing the remaining parameters were kept as ‘default’. The ‘Open Babel Linear Fingerprint’ was used for the analyses of molecular descriptors, followed by ADME-check. Results: 4-(4-Methyl-1-piperazinyl)-2-phenyl[1]benzofuro[3,2-d]pyrimidine corresponding to the MCULE ID-7590816301-0-93 exhibited the overall best binding with TS. The free energy of binding was -8.6 kcal/mol. A total of 17 amino acid residues were significant for the binding interactions. Importantly, 9 residues were common to methotrexate binding. It satisfied pertinent ADME conditions. Conclusion: 4-(4-Methyl-1-piperazinyl)-2-phenyl[1]benzofuro[3,2-d]pyrimidinemay emerge as a potent seed molecule for TS-inhibitor design in the context of rheumatoid arthritis. It has satisfied pertinent ADME features. However, there is need for further wet laboratory validation. Keywords: Anti-rheumatoid arthritis, Inhibitor design, Methotrexate, Seed molecule, Thymidylate synthase, Virtual screenin

Musculoskeletal manifestations in diabetic patients at a tertiary center

Objectives: Diabetes mellitus is a major public health problem worldwide. Most diabetic patients will develop functional disabilities due to multiple factors, including musculoskeletal (MSK) manifestations. The purpose of this study was to determine the frequency of MSK in diabetic patients and to examine the possible predictors for its development. Methods: We performed a cross-sectional study from June 1, 2010, to June 30, 2011, to evaluate MSK manifestations in adult diabetic patients at an outpatient clinic of King Abdulaziz University Hospital, Jeddah, Saudi Arabia. Baseline variables were examined to determine predictors for the development of MSK complications. Analyses were carried out using the Statistical Package for Social sciences. Results: We included 252 diabetic patients; 45 (17.9%) had MSK manifestations. Of these 45 patients, 41 (91.1%) had type 2 diabetes. The most common manifestations were carpal tunnel syndrome (n=17, 6.7%), shoulder adhesive capsulitis (n=17, 6.7%), and diabetic amyotrophy (n=12, 4.8%). A significant association was found between the development of MSK manifestations and manual labor, overweight, and vascular complications. On logistic regression analysis, the presence of vascular complications in general (B-coefficient=1.27, odds ratio=3.57, P<0.05, 95% confidence interval=1.31–9.78), and retinopathy in particular (B-coefficient=1.17, odds ratio=3.21, P<0.05, 95% confidence interval=1.47–7.02) can predict the development of MSK manifestations in about 82% of the cases. Conclusion: Musculoskeletal manifestations are under recognized in adult diabetic patients, occurring in 18% of the cases. Physicians should consider examining the periarticular region of the joints in the hands and shoulders whenever a diabetic patient presents with MSK symptoms

Vitamin D Deficiency in Patients with Systemic Lupus Erythematosus

Objectives: Hypovitaminosis D is common in the general population. Many studies that have been conducted to show the association between vitamin D deficiency and systemic lupus erythematosus (SLE) reveal that deficiencies in vitamin D are common in this group of patients. Our aim was to study the relationship between 25(OH)D and disease activity in patients with SLE.Methods: Retrospective cohort study of patients with SLE who were followed up at King Abdulaziz University Hospital, Jeddah, from January 2007 to November 2010. Demographic and clinical data were recorded and the 25(OH)D levels of the patients were measured. Chi square tests, Student’s t-test, ANOVA and Pearson tests were used for data analysis. ANOVA test was followed by Bonferroni correction. A p-value <0.05 was considered significant.Results: Ninety-five patients with SLE were enrolled in the study. The levels of 25(OH)D were significantly lower in patients with active SLE (n=41; 43%) than in those with inactive disease (n=54; 57%; p=0.04). The mean (SD) levels were 22.3 (14) nmol/L for patients with active disease against 25.0 (14) nmol/L for patients with inactive SLE. No correlation was detected between 25(OH) D levels and disease activity score evaluated by SLEDAI-2K. By Pearson correlation, a significant negative correlation existed between 25(OH) D and anti ds-DNA (r=-0.38; p<0.001); a positive correlation existed between 25(OH)D levels and C4 (r=0.25; p=0.25). By chi square testing, azathioprine treatment (OR=3.5), low C4 (OR= 2.23), low C3 (OR=1.92), and active disease (OR=1.6) were associated with 25(OH)D deficiency in SLE patients.Conclusion: Vitamin D deficiency is frequent in patients with SLE. Patients with SLE have a higher risk of developing 25(OH)D deficiency in the presence of low serum C3 and C4 levels, and high anti-dsDNA levels

Extra-articular manifestations of rheumatoid arthritis: a hospital-based study

<b>Background and Objective: </b> The frequency of extra-articular manifestations in rheumatoid arthritis (ExRA) differs from one country to another, so we investigated ExRA frequency in a well-defined hospital patient popula--tion with rheumatoid arthritis (RA) in Saudi Arabia. We also examined possible predictors of the development ExRA. <b> Methods: </b> A retrospective analysis was conducted of all patients diagnosed with RA at a university hospital dur--ing a 4-year period. Cases were classified according to the 1987 American College of Rheumatology criteria for RA, and the frequency of ExRA was recorded. <b> Results: </b> Of 140 patients who fulfilled the criteria for the diagnosis of RA, 98 (70&#x0025;) developed ExRA features. Anemia occurred in 61&#x0025;, thrombocytosis in 16&#x0025;, pulmonary involvement in 10&#x0025;, and renal amyloidosis, vas--culitis and Felty syndrome were present in 6&#x0025;, 2&#x0025; and 1&#x0025;, respectively. The mortality rate was high (16&#x0025;) in patients with ExRA. The predictors for mortality were lung involvement, age over 50 years and kidney amyloidosis. <b> Conclusion: </b> ExRA were present in a substantial proportion of our patients, which lead to a worse disease outcome. Anemia, thrombocytosis and respiratory system involvement were the commonest. Early recognition and treatment are important to decrease mortality