In silico analysis of the structural and functional implications of SLC19A1 R27H polymorphism

In view of the documented association of solute carrier family 19 member 1 (SLC19A1) G80A (R27H) polymorphism with the risk for different types of cancers and systemic lupus erythematosus (SLE), we have reanalysed the case–control study on breast cancer to ascertain the conditions in which this polymorphic variant exerts the risk of breast cancer. Association statistics have revealed that this polymorphism exerts the risk for breast cancer under the conditions of low folate intake, and in the absence of well-documented protective polymorphism in cytosolic serine hydroxymethyltransferase. To substantiate this observation, we have developed a homology model of SLC19A1 using glycerol-3-phosphate transporter (d1pw4a) as a template where 73% of the residues were modelled at 90% confidence while 162 residues were modelled ab initio. The wild and mutant proteins shared same topology in S3, S5, S6, S7, S11 and S12 transmembrane domains. The topology varied at S1 (28–43 residue vs 28–44 residue), S2 (66–87 residue vs 69–87 residue), S4 (117–140 residue vs 117–139 residue), S8 (305–325 residue vs 305–324 residue), S9 (336–356 residue vs 336–355residue), and S10 (361–386 residue vs 361–385 residue) transmembrane domains between wild versus mutant proteins. S2 domain is shortened by three amino acid residues in themutantwhile in other domains the difference corresponds to one amino acid residue. The 3DLigandSite analysis revealed that the metallic-ligand-binding sites at 273Trp, 277Asn, 379Leu, 439Phe and 442Leu are although unaffected, there is a loss of active sites corresponding to nonmetallic ligand binding. Tetrahydrofolate and methotrexate have lesseraffinity towards the mutant protein than the wild protein. To conclude, the R27H polymorphism affects the secondary and tertiary structures of SLC19A1 with the significant loss in ligand-binding sites.

Application of multiple linear regression and machine learning algorithms to elucidate the association of poor glycemic control and hyperhomocysteinemia with microalbuminuria

Microalbuminuria is an early biomarker of general vascular dysfunction and a predictor of risk for cardiovascular and renal diseases. It is also considered as a marker of insulin resistance in both diabetic and non-diabetic patients. The rationale of this study was to elucidate threshold values of fasting blood glucose (FBS) and glycosylated hemoglobin (HbA1c) that are associated with microalbuminuria. In the parallel association of microalbuminuria with hyperhomocysteinemia was investigated. Machine learning algorithm and multiple linear regression were applied to study the association of poor glycemic control on microalbuminuria and hyperhomocysteinemia. In non-diabetic subjects with FBS <102 mg/dL and HbA1c <6.3%; and in diabetic subjects with good glycemic control (FBS: 102-118 mg/dL; HbA1c: 6.3-7.0%), urinary microalbumin levels were <40µg/mg creatinine. Poor glycemic control (FBS >172 mg/dL and HbA1c >9.0%) was associated with microalbumin >40µg/mg creatinine. Age, gender, HbA1c and FBS were shown to explain variability in urinary microalbumin to the extent of 54.4% as shown by multiple linear regression model. Analysis of variance (ANOVA) revealed higher levels of FBS (F: 39.77, P <0.0001), HbA1c (F: 64.31, P <0.0001) and total plasma homocysteine (F: 3.69, P =0.04) in microalbuminuria and clinical microalbuminuria groups when compared to subjects with normal microalbumin levels. Diabetic patients with poor glycemic index had a more B12 deficiency. Poor glycemic index and hyperhomocysteinemia were associated with clinical microalbuminuria.

Syzygium aromaticum extracts as good source of betulinic acid and potential anti-breast cancer

Syzygium aromaticum (L.) Merr. & L.M. Perry, Myrtaceae, is an evergreen tree with anticarcinogenic, antimutagenic, aphrodisiac, antimicrobial, antioxidant and antiinflammatory properties. This study aims to investigate the anti-breast cancer effect of extracts from leaves, stem and bark of S. aromaticum and to develop a method for preparation of betulinic acid fraction from the leaves. Betulinic acid, ursolic acid and oleanolic acid contents of the extracts were determined by HPLC. A betulinic acid fraction was prepared by simple crystallization of leaves extract and was characterized by HPLC and mass analysis. Anti-breast cancer effects were studied on MCF-7 and MDA-MB-231 cells. The extracts were found to contain high levels of betulinic acid particularly the leaves extract which contained 17% wt/wt. The betulinic acid fraction contains 75% betulinic acid. Cytotoxicity testing reveals high and selective cytotoxic effect of the stem extract on MCF-7 cells with IC50 33±1.6 µg/mL. Cytotoxic effect of the stem extract was due to activation of apoptotic machinery of cell death. Combination studies of stem extract with tamoxifen reveals antagonistic effect at high concentration of tamoxifen and enhancement effect at low concentration. The selective cytotoxicity of the stem extract of S. aromaticum on MCF-7 is not due to betulinic acid but due to other constituents yet to be discovered.