Aparna R. Bitla

Para-(benzoyl)-phenylalanine as a potential inhibitor against LpxC of Leptospira spp.: homology modeling, docking, and molecular dynamics study

Leptospira interrogans, a Gram-negative bacterial pathogen is the main cause of human leptospirosis. Lipid A is a highly immunoreactive endotoxic center of lipopolysaccharide (LPS) that anchors LPS into the outer membrane of Leptospira. Discovery of compounds inhibiting lipid-A biosynthetic pathway would be promising for dissolving the structural integrity of membrane leading to cell lysis and death of Leptospira. LpxC, a unique enzyme of lipid-A biosynthetic pathway was identified as common drug target of Leptospira. Herein, homology modeling, docking, and molecular dynamics (MD) simulations were employed to discover potential inhibitors of LpxC. A reliable tertiary structure of LpxC in complex with inhibitor BB-78485 was constructed in Modeller 9v8. A data-set of BB-78485 structural analogs were docked with LpxC in Maestro v9.2 virtual screening workflow, which implements three stage Glide docking protocol. Twelve lead molecules with better XP Gscore compared to BB-78485 were proposed as potential inhibitors of LpxC. Para-(benzoyl)-phenylalanine – that showed lowest XP Gscore (−10.35 kcal/mol) – was predicted to have best binding affinity towards LpxC. MD simulations were performed for LpxC and para-(benzoyl)-phenylalanine docking complex in Desmond v3.0. Trajectory analysis showed the docking complex and inter-molecular interactions was stable throughout the entire production part of MD simulations. The results indicate para-(benzoyl)-phenylalanine as a potent drug molecule against leptospirosis. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:10

Association of lipid peroxidation with endothelial dysfunction in patients with overt hypothyroidism.

Hypothyroidism is associated with increased oxidative stress. The mechanism underlying the endothelial dysfunction in thyroid disease is not yet clear. This study aims to investigate lipid peroxidation and its association with endothelial dysfunction in overt hypothyroidism (OHT).Plasma malondialdehyde (MDA) as a marker of oxidative stress and plasma nitrates and asymmetric dimethyl arginine levels (ADMA) as markers of endothelial dysfunction were estimated in 25 OHT patients in comparison to 25 euthyroid controls. Plasma MDA, ADMA levels were significantly increased, whereas plasma nitrates were significantly decreased in the patient group compared to control group (p<0.01). Moreover, a significant positive association between plasma MDA and ADMA was found in the patient group (ρ=0.472, p=0.036). Our results reveal the presence of endothelial dysfunction in OHT patients as evidenced by decreased plasma nitrates and increased ADMA levels. Increased levels of MDA represent an increased generation of reactive oxygen species in these patients. A finding of significant direct relation of plasma MDA with ADMA indicates that oxidative stress has a strong impact on endothelial dysfunction in overt hypothyroidism. Further studies focusing on the role of oxidative stress in endothelial dysfunction and the effects of antioxidant supplementation on endothelial function in OHT patients are required.

Effect of a single hemodialysis session on endothelial dysfunction

BACKGROUND The mechanisms of endothelial dysfunction induced by hemodialysis are unclear. To gain a mechanistic view we have evaluated some of the biochemical markers which directly or indirectly lead to endothelial dysfunction during a single dialysis session. METHODS Time course changes in plasma nitrate levels, arginine (ARG), citrulline, asymmetric dimethylarginine (ADMA), homocysteine (Hcy), malondialdehyde (MDA) and lipoprotein-associated phospholipase A2 (LpPLA2) were evaluated in 27 patients with end-stage renal disease on maintenance hemodialysis. Statistical evaluation of changes was done using analysis of variance for repeated measures and linear regression using generalized estimating equations for repeated measures. RESULTS Nitrate levels significantly increased as a result of dialysis (p<0.001). Hcy (p<0.05) and ADMA (p<0.001) levels were found to be significantly decreased. ARG/ADMA ratio showed an increase (p<0.001). Presence of oxidative stress (OS) was observed in the form of increased plasma MDA levels. Nitrate levels were negatively associated with Hcy, ADMA and LpPLA2 activity. CONCLUSION Our results show an increased production of nitric oxide (NO) during dialysis, which however is affected by increased OS ultimately favoring endothelial dysfunction. Measures to reduce the OS during hemodialysis are needed to get the complete benefit of clearance of circulating inhibitors of NO synthase during dialysis.

Oxidative stress in non-obese women with polycystic ovarian syndrome.

BACKGROUND Polycystic ovarian syndrome (PCOS) is one of the most common endocrine diseases of women. Oxidative stress is an important component of the cardio-metabolic risk seen in these women. Oxidative stress has been reported in obese PCOS women. This study is taken up to study oxidative stress in non-obese PCOS women. MATERIALS AND METHODS Twenty five non-obese women with PCOS attending the Endocrinology outpatient Department of Sri Venkateswara Institute of Medical Sciences, Tirupati, India along with 25 healthy BMI matched controls were included in the study. The changes in the lipid peroxidation products (MDA), and total anti oxidant capacity (FRAP) as an index of anti oxidant status along with fasting glucose, insulin and uric acid levels were measured in both groups. Insulin resistance was evaluated by using homeostasis model assessment for insulin resistance [HOMA-IR)= [FPG (mg/dl) × insulin (mIU/L)]/ 405] in both groups. RESULTS Serum MDA and uric acid levels were increased in the study group compared with controls and FRAP levels were decreased in the study group compared to controls though statistically insignificant. CONCLUSION Oxidative stress is also present in non-obese women with PCOS. Oxidative stress further increases the CVD risk in these women.Correcting oxidative stress with antioxidants along with monitoring the antioxidant status using a simple assay like FRAP could have a beneficial effect on oxidative stress induced insulin resistance and hyperandrogenism seen in these women.

Serum Adenosine Deaminase as Inflammatory Marker in Rheumatoid Arthritis.

BACKGROUND Rheumatoid arthritis (RA) is a prototypical inflammatory joint disease. The degree of inflammation is reflected in the extent of joint damage, which further has influence on the quality of life of patients with RA, including risk of atherosclerosis. Hence, besides clinical indices, estimation of degree of inflammation using biochemical markers helps in effecting optimum treatment strategies. C-reactive protein (CRP) is established as an inflammatory marker in patients with RA. Adenosine deaminase (ADA), an enzyme of purine metabolism is considered as a marker of cell mediated immunity and has also been suggested as a marker of inflammatory process in RA. The present study attempts to study the efficacy of serum ADA activity as an inflammatory marker in RA. MATERIALS AND METHODS Forty six RA patients and forty six age and sex matched healthy controls were included in the study. ADA activity and high sensitivity C-reactive protein (hsCRP) levels in serum were measured in all the subjects. Statistical analyses were done using Medcalc statistical software version 12.2.2. RESULTS ADA activity and hsCRP levels were increased in RA patients compared to controls (p<0.0001 and 0.0001 respectively). Significant positive correlation was obtained between hsCRP and ADA in patients (r=0.316, p=0.033). Receiver operating characteristic (ROC) curve analysis revealed statistically significant area under curve (AUC) for ADA that is comparable to that obtained for hsCRP (0.776, p<0.0001 for ADA, 0.726, p<0.0001 for hsCRP). Similar diagnostic utility was obtained with ROC generated cut-off value of 25.3 IU/L (82.6% sensitivity and 65.2% specificity) and with control mean value of 23.48 IU/L (86.96% sensitivity and 54.35% specificity) for ADA. CONCLUSION Findings of the present study indicate the importance of ADA as a marker of inflammation. Considering the higher sensitivity obtained, we propose control mean (23.48 IU/L) as a cut-off for serum ADA activity as an inflammatory marker. Owing to the simplicity and also the cost effectiveness of ADA assay, ADA may be recommended as a marker of inflammation in patients with RA. However, further larger and well controlled studies are needed to establish its role as inflammatory marker.

Effect of a single hemodialysis session on inflammatory markers.

Inflammation is a common feature of end‐stage renal disease. Although there is evidence for hemodialysis (HD)‐induced inflammatory process, the effect of a dialysis session on changes in inflammatory markers is still unclear. Seventeen patients of end‐stage renal disease on maintenance HD along with 20 age‐matched and sex‐matched healthy controls were recruited after informed consent. C‐reactive protein (CRP) and lipoprotein‐associated phospholipase A2 (LpPLA2) activity were measured in the study and control groups. Intradialytic in CRP and LpPLA2 were studied. Comparison of pre‐HD vs. the control group and predialytic and postdialytic values was performed using the Mann‐Whitney U test and Wilcoxons test, respectively. Statistical evaluation of intradialytic changes in inflammatory markers was performed using Friedmans test. Hemodialysis patients had higher CRP levels compared with controls (P=0.001). Post‐HD LpPLA2 activity (n=17) was higher (P=0.039) compared with the pre‐HD activity. Intradialytic changes in inflammatory markers showed a significant increase (P=0.012) in LpPLA2 activity (n=7), while no change (P=0.133) was observed in CRP levels (n=17). Evidence on the pro‐inflammatory state being initiated by dialysis is provided by increased LpPLA2 activity. This may add to the atherogenic mileu and cause endothelial dysfunction in this high‐risk group. Drugs that inhibit the LpPLA2 pathway have been developed and may be effective in these patients.

Nitric oxide status in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) are at an increased risk of cardiovascular (CVD) morbidity and mortality, mainly due to atherosclerosis. Decreased production or reduced bioavailability of nitric oxide (NO) can result in endothelial dysfunction (ED). Multiple mechanisms are known to cause a state of NO deficiency in patients with CKD. Patients in various stages of CKD grouped as group-1 (CKD stage 1 and 2), group-2 (CKD stage 3 and 4), group-3 (CKD stage 5) and healthy controls were included in the study. Each group of patients and controls comprised 25 subjects. Plasma nitrites, L-arginine, asymmetric dimethyl arginine (ADMA) and citrulline were measured in all the subjects. Patients in all stages of CKD had lower NO and higher ADMA levels compared to controls. Further, group-2 and group-3 patients had lower levels of NO and higher levels of ADMA than group-1 patients. L-arginine levels showed no difference between patients and controls. However, group-3 patients had lower L-arginine levels compared to group-1 patients. Citrulline levels were decreased in group-3 patients. NO production was decreased in patients in all stages of CKD. The decrease could be due to decreased availability of the substrate, L-arginine or due to an increased ADMA, a potent inhibitor of endothelial NO synthase. Therapeutic interventions directed towards improvement of NO production in addition to management of other CVD risk factors may prevent development of ED and facilitate proper management of CKD patients who are at increased risk for CVD.

Utility of saliva as a sample to assess renal function and estimated glomerular filtration rate.

Diagnosis of renal diseases by assessing renal parameters in saliva. Biochemical investigations using serum form important component of monitoring patients with renal disease. Utility of saliva, in diagnosis and monitoring of patients with renal disease and for calculation of estimated glomerular filtration rate (eGFR), was studied. Sixty patients with renal disease and sixty ageand sex-matched healthy controls were studied. Urea, creatinine, sodium, potassium, uric acid, calcium, and phosphorus were measured in both serum and saliva. eGFR was calculated using salivary creatinine. Data were expressed as mean ± standard deviation. Comparison and correlation between groups were assessed by Students t-test and Pearson correlation, respectively. Bland-Altman plot, mountain plot, and intra-class correlation coefficient were used to test agreement. A P <0.05 was considered statistically significant. Statistical analysis was done using Microsoft excel spreadsheets, Medcalc Version 10.0, and SPSS version 11.5. Salivary levels of urea, creatinine, uric acid, sodium, potassium, and phosphorus were higher in patients compared to controls. Potassium and phosphorus levels were higher (P = 0.001) and creatinine, sodium, calcium, and uric acid levels were lower (P = 0.001) in saliva compared to serum in both patients and controls. Positive correlation was observed between serum and salivary urea and creatinine (P < 0.0001). eGFR values calculated from salivary creatinine showed good agreement with those calculated form serum creatinine. Salivary urea (>6 mmol/L) and creatinine (>14.6 μmol/L) and eGFR calculated from salivary creatinine can be used to identify patients with renal disease.

Branched chain amino acid profile in early chronic kidney disease

The nutritional status in chronic kidney disease (CKD) patients is a predictor of prognosis during the first period of dialysis. Serum albumin is the most commonly used nutritional marker. Another index is plasma amino acid profile. Of these, the plasma levels of branched chain amino acids (BCAA), especially valine and leucine, correlate well with nutritional status. Plasma BCAAs were evaluated along with albumin and C-reactive protein in 15 patients of early stages of CKD and 15 age- and sex-matched healthy controls. A significant decrease in plasma valine, leucine and albumin levels was observed in CKD patients when compared with the controls (P <0.05). No significant difference in C-reactive protein (CRP) levels was observed between the two groups. Malnutrition seen in our CKD patients in the form of hypoalbuminemia and decreased concentrations of BCAA points to the need to evaluate the nutritional status in the early stages itself. Simple measures in the form of amino acid supplementation should be instituted early to decrease the morbidity and mortality before start of dialysis in these patients.

Effect of lifestyle modification and metformin therapy on emerging cardiovascular risk factors in overweight Indian women with polycystic ovary syndrome.

INTRODUCTION Polycystic ovarian syndrome (PCOS) is common among women of reproductive age. Although traditional cardiac risk factors are known to be altered and improved with short-term metformin therapy, not much is known about novel cardiac risk factors. OBJECTIVE The aim of this study was to evaluate the effects of lifestyle modification and short-term metformin therapy on the fasting serum lipids, homeostasis model assessment of insulin resistance (HOMA-IR), serum high-sensitivity C-reactive protein (hsCRP), and serum homocysteine. METHODS Native overweight [body mass index (BMI) >23 kg/m(2)] Indian women diagnosed with PCOS were evaluated and subjected to an oral glucose tolerance test and determination of insulin, homocysteine, hsCRP, and fasting lipids levels. They were started on maximally tolerated doses of metformin along with lifestyle modification. Following 3 months of therapy, they were resampled. RESULTS Out of 36 consecutive patients included, 25 women completed 3 months of metformin treatment and were eligible for repeat evaluation. The age of study group was 22.2 ± 5 years. Twenty-two (61%) women were obese (BMI >25 kg/m(2)). Improvement was seen in body weight, BMI, serum total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), hsCRP, and serum testosterone on metformin therapy. However, no improvement was seen in serum fasting insulin, HOMA-IR, or homocysteine. CONCLUSION Serum hsCRP improved with lifestyle modification and metformin therapy for 3 months in overweight subjects from India with PCOS, along with serum total cholesterol, triglycerides, and HDL-C. However, markers of insulin resistance and serum homocysteine did not improve.