Use of appropriate statistical tools in biomedical research: Current trend & status.

Background & objectives: Due to lack of appropriate statistical knowledge, published research articles contain various errors related to the design, analysis and interpretation of results in the area of biomedical research. If research contains statistical error, however, costly, it may be of no use and the purpose of the investigation gets defeated. Many biomedical research articles published in different peer reviewed journals may retain several statistical errors and flaws in them. This study aimed to examine the trend and status of application of statistics in biomedical research articles. Study design, sample size estimation and statistical measures are crucial components of a study. These points were evaluated in published original research articles to understand the use or misuse of statistical tools. Methods: Three hundred original research articles from the latest issues of selected 37 journals were reviewed. These journals were from the five internationally recognized publication groups (CLINICAL KEY, BMJ Group, WILEY, CAMBRIDGE and OXFORD) accessible through the online library of SGPGI, Lucknow, India. Results: Among articles assessed under present investigation, 85.3 per cent (n=256) were observational, and 14.7 per cent (n=44) were interventional studies. In 93 per cent (n=279) of research articles, sample size estimation was not reproducible. The simple random sampling was encountered rarely in biomedical studies even though none of the articles was adjusted by design effect and, only five articles had used randomized test. The testing of assumption of normality was mentioned in only four studies before applying parametric tests. Interpretation & conclusions: In order to present biomedical research results with reliable and precise estimates based on data, the role of engaging statistical experts need to be appreciated. Journals must have standard rules for reporting study design, sample size and data analysis tools. Careful attention is needed while applying any statistical procedure as, it will not only help readers to trust in the published articles, but also rely on the inferences the published articles draw.

Prevalence and Associated Factors of Cesarean Section in Dhulikhel Hospital, Kathmandu University Hospital.

Background The Cesarean Section (CS) is a major obstetric life-saving procedure used to avoid pregnancy and childbirth complications. Cesarean sections are becoming more popular across the world, as well as in Nepal. Objective To assess the prevalence of cesarean section and its associated factors among women in Dhulikhel, Nepal. Method A cross-sectional study was conducted where 1246 pregnant women of age 15-45 years, admitted and delivered in hospital, were selected through purposive sampling technique and interviewed using structured questionnaires in Dhulikhel Hospital, Kathmandu University Hospital, Kavre, Nepal. Result The prevalence of cesarean section among women was 39.7% where the most common indication was previous cesarean section with scar tenderness, 27.9%. Half of the participants, i.e. 50.6%, were primigravida. Majority of women, 97.5% had done their antenatal checkup and among them 74.8% had their checkup in Dhulikhel Hospital, Kathmandu University Hospital. Most of them, i.e.76.2% had emergency cesarean section and 69.5% had primary cesarean section. Women of the age group 30-45 years (AOR=2.23) and women with higher secondary education level (AOR=2.03) were two times more likely to perform cesarean section. Women involved in service (AOR=1.37) and business (AOR=1.23) had greater odds of performing cesarean section than homemakers. Women giving birth to infants weighing 3.51- 5.00 kg were more likely to perform cesarean section (AOR=1.33). Conclusion The prevalence of cesarean section is noticeably high where the educated, employed and higher aged women are more inclined to cesarean section. More obstetric factors could be explored to determine the rise in cesarean section in Nepal which can help in decision making for clinicians.

Exiguobacterium: an overview of a versatile genus with potential in industry and agriculture.

The bacterial genus Exiguobacterium accommodates many versatile species isolated from diverse environments. Exiguobacterium was described as a genus approximately three decades ago, and now, 17 species, growing over a broad range of temperatures and pH, have been recognized. Various isolates from different niches have been explored for biotechnological and industrial purposes, including enzyme production, bioremediation and degradation of toxic substances released into the environment. Some isolates possess plant growth promoting capabilities, and they are currently being explored for increasing agricultural production. The genome sequences of various strains of this genus have shown the presence of many genes encoding products of importance to agriculture and the environment. In addition, many strains possess stress-responsive genes helping them to colonize and thrive in diverse ecological niches. This review provides a broad view of the versatile genus Exiguobacterium and its potential for applications in agriculture, the environment and industry, as well as the underlying genomic determinants that drive its diversity and adaptability to various extreme environments.

Long-term outcomes post chronic total occlusion intervention-implications of completeness of revascularization.

BACKGROUND: Long term clinical outcomes post chronic total occlusion (CTO) intervention may depend not only on CTO success/failure alone but also on Completeness of revascularization. OBJECTIVES: To determine long term outcomes post CTO intervention and relate them to both success versus failure and Complete Revascularization (CR) versus Incomplete Revascularization (IR). METHODS: Consecutive patients taken up for CTO intervention with at-least one CTO vessel between Jan 2006 to Dec 2015 were included. Clinical, procedural and follow up details were recorded in a pre-specified custom made software. Primary endpoint of the study was survival free of major adverse event individual, death, myocardial infarction (MI), repeat revascularisation (percutaneous coronary intervention [PCI], or coronary artery bypass grafting (CABG) and recurrent or continued angina. Each individual adverse event was considered as a secondary end point. RESULTS: A total of 632 patients were enrolled in study with follow up data available in 549 (86%) constituting the study group with 490 (89.3%) success and 59 (11.7%) failure. Complete revascularization (CR) was obtained in 410 (74.7%). Follow up was median 2.9 years with inter-quartile range 1.1-4.8 years. Kaplan Meier survival analysis showed a better EFS with both CTO success versus failure (P = 0.03)and CR versus IR (P = 0.017). Individual adverse outcomes however were not significantly different in CTO success versus failure group but significantly better when analyzed with respect to CR versus IR including death (P = 0.049) and recurrent angina (P = 0.024). Repeat intervention and MI were not different by either analysis. CONCLUSIONS: Successful CTO PCI results in a better long term event free survival but the difference between the groups is more if analyzed with respect to completeness of revascularization rather than CTO success/failure alone.

Multiparametric imaging-based differentiation of lymphoma and glioblastoma: using T1-perfusion, diffusion, and susceptibility-weighted MRI.

AIM: To compare the diagnostic performance of T1 perfusion magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), and susceptibility-weighted imaging (SWI) for differentiating primary central nervous system lymphoma (PCNSL) and glioblastoma (GBM). MATERIALS AND METHODS: This retrospective study comprised a cohort of 70 patients with glioblastoma and 30 patients with PCNSL. T1 perfusion MRI-derived rCBV_corr (leakage corrected relative cerebral blood volume), apparent diffusion coefficient (ADC) derived from DWI, and intratumoural susceptibility signals intensity (ITSS) measured on SWI were evaluated in these 100 patients. The Mann-Whitney U-test was used for pairwise comparison between groups. The diagnostic performance for differentiating PCNSL from glioblastoma was evaluated by using univariate and multivariable logistic regression analyses and receiver operating characteristic (ROC) analysis. RESULTS: Minimum ADC, maximum rCBVs_corr, kep (back flux exchange rate), and ITSS scores were significantly lower in patients with PCNSL than in those with glioblastoma (p<0.05). On ROC analysis, ITSS showed the best discrimination ability for differentiation of GBM and PCNSL with an area under the ROC curve (AUC) of 0.80. rCBV_corr and ADC showed AUCs of 0.68 and 0.63, respectively. Multiparametric assessment using ADC, rCBV_corr, kep, and ITSS scores significantly increased the diagnostic ability for differentiating PCNSL from GBM as compared to mean ADC, mean rCBV_corr, and ITSS alone or a combination of these parameters. The multiparametric model could correctly discriminate 84% of tumours with a sensitivity and specificity of 90% and 70% with an AUC of 0.92. CONCLUSION: Multiparametric MRI evaluation using DWI, T1 perfusion MRI, and SWI enabled reliable differentiation of PCNSL and GBM in the majority patients, and these results support an integration of advanced MRI techniques for the diagnostic work-up of patients with these tumours.

Serial perioperative cell-free DNA levels in donors and recipients undergoing living donor liver transplantation.

BACKGROUND: Effect of anaesthesia and surgery on cell-free DNA (cfDNA) is not known. Given that surgical stress augments inflammation and injury, we hypothesized that levels of cfDNA will fluctuate during perioperative period. Therefore, in this study serial perioperative cfDNA concentration was measured in donors and recipients undergoing living donor liver transplantation (LDLT). METHODS: Baseline, post-induction, intraoperative and post-operative plasma cfDNA levels were evaluated in 21 donors and recipients each, by Sytox green method. In addition, qPCR was performed in a subset of samples. RESULTS: Baseline cfDNA levels were higher in recipients (37.62 ng/ml) than in donors (25.49 ng/ml). A decrease in cfDNA was observed following anaesthesia induction in both recipients (11.90 ng/ml) and donors (10.75 ng/ml). When the kinetics of the cfDNA was monitored further, an increase was noted intraoperatively in donors (46.18 ng/ml) and recipients (anhepatic phase: 56.25 ng/ml, reperfusion phase: 54.36 ng/ml). cfDNA levels remained high post-operatively. One recipient who developed post-operative sepsis had the highest cfDNA level (94.72 ng/ml). CONCLUSION: Plasma cfDNA levels are high in recipients indicative of liver injury. Lower cfDNA levels following induction may be attributed to the subduing effect of anaesthetic agents on cell death. High cfDNA levels seen in intra- and post-operative phases reflect cellular trauma and inflammation. This similar pattern of fluctuation of cfDNA level in donors and recipients is suggestive of its possible utility as a surgical stress marker. In addition, comparable cfDNA levels in anhepatic and reperfusion phase reflect less ischemia reperfusion injury during LDLT.

Neurofibromatosis-I Presentating with Multiple Spinal and Intracranial Neurofibromas.

Von Recklinghausen's neurofibromatosis (NF-1) is a phacomatosis characterised by widespread nervous system tumours with cutaneous manifestations and variably associated anomalies. We report here a case, who, in addition to classical features of NF-1 (café-au-lait spots, cutaneous and subcutaneous neurofibromas) demonstrated radiological evidence of both spinal and intracranial neurofibromas and an incidentally discovered horse-shoe kidney. The unique constellation of spinal and intracranial neurofibromas, with associated horse-shoe kidney.

Postoperative coagulopathy after live related donor hepatectomy: Incidence, predictors and implications for safety of thoracic epidural catheter.

BACKGROUND: Coagulopathy after living donor hepatectomy (LDH) may endanger donor safety during removal of thoracic epidural catheter (TEC). The present study was conducted to evaluate the extent and duration of immediate postoperative coagulopathy after LDH. MATERIALS AND METHODS: A retrospective analysis of perioperative record of LDH over three years was conducted after IRB approval. Variables such as age, gender, BMI, ASA classification, liver volume on CT scan, preoperative and postoperative INR, platelet count (PC) and ALT of each donor for five days was noted. In addition, duration of surgery, remnant as percentage total liver volume (Remnant%), blood loss, day of peak in PC and INR were also noted. Coagulopathy was defined as being present if INR exceeded 1.5 or platelet count fell below 1 × 10 5 /mm 3 on any day. Data was analyzed using SPSS 20 for Windows. Between group comparison was made using the Student 't' test for continuous variables and chi square test for categorical variables. Univariate analysis was done. Multiple logistic regression analysis was used to find independent factor associated with coagulopathy. RESULTS: Eighty four (84) donors had coagulopathy on second day (mean INR 1.9 ± 0.42). Low BMI, % of remnant liver and duration of surgery were independent predictors of coagulopathy. Right lobe hepatectomy had more coagulopathy than left lobe and low BMI was the only independent predictor. There was no correlation of coagulopathy with age, gender, blood loss, presence of epidural catheter, postoperative ALT or duration of hospital stay. High INR was the main contributor for coagulopathy. CONCLUSIONS: Coagulopathy is seen after donor hepatectomy. We recommend removal of the epidural catheter after the fifth postoperative day when INR falls below 1.5.

Brachial plexus injury in live related donor hepatectomy: a chart review.

Retrieval of the partial liver graft is a complicated and time-consuming procedure and reported to be associated with brachial plexus injury. We present a case series of brachial plexus injury in live related donor hepatectomy of 95 donors analyzed retrospectively. Seven donors suffered from brachial plexus injuries of varying severity and duration. Out of these, one donor had residual paresis. The reasons could be application of retractors, which may have led to traction and compression above the nerve roots.

Comparative evaluation of prophylactic use of pregabalin, gabapentin and diclofenac sodium for prevention of succinylcholine-induced myalgia: a randomized, double-blinded study.

CONTEXT: Succinylcholine a depolarizing muscle relaxant with rapid onset, predictable course and short duration of action is associated with myalgia. AIM: The aim of this study is to evaluate the efficacy of pregabalin, gabapentin and diclofenac on the incidence and severity of succinylcholine-induced myalgia. SETTINGS AND DESIGN: Tertiary Care Teaching Hospital. MATERIALS AND METHODS: A total of 120 patients undergoing laparoscopic cholecystectomy were randomly assigned into three groups: Pregabalin group received 150 mg of pregabalin, gabapentin group received 600 mg of gabapentin and diclofenac group received 100 mg of diclofenac sodium orally 2 h prior to surgery. Anesthesia was induced with fentanyl 3 µg/kg, propofol 2-2.5 mg/kg and succinylcholine 1.5 mg/kg and was maintained with oxygen with sevoflurane in the air and intermittent vecuronium bromide. A blinded observer recorded post-operative pain scores on visual analog scale at different time intervals and myalgia at 24 h. Post-operative pain relief was provided with fentanyl based patient-controlled analgesia. Fentanyl consumption in 24 h was recorded as a primary outcome. STATISTICAL ANALYSIS: Patients' characteristics and total fentanyl consumption were compared using one-way ANOVA followed by post-hoc test. Pain score was compared amongst the groups using Kruskal Wallis test. RESULTS: The myalgia occurred in 15, 14 and 13 patients in pregabalin, gabapentin and diclofenac sodium group respectively (P > 0.85). Patients in diclofenac group had significantly higher fentanyl consumption (674.85 ± 115.58 µg) compared with pregabalin group (601.87 ± 129.57 µg) (95% confidence interval [CI] = 34.8-120.7) and gabapentin group (612.29 ± 105.12 µg) (95% CI = 14.9-170.5). However, there was no significant difference in fentanyl consumption between pregabalin and gabapentin groups (95% CI = -34.8-120.7). There was a significant difference in visual analog score at time points 12, 18 and 24 h among the study groups. CONCLUSION: Pre-treatment with pregabalin, gabapentin and diclofenac had equal efficacy in reducing the incidence and severity of succinylcholine-induced myalgia. However, pre-treatment with pregabalin and gabapentin decreased post-operative pain scores and fentanyl consumption.

Hepatorenal syndrome: a decade later.

Hepatorenal syndrome is a unique form of acute kidney injury seen in patients with acute liver failure or chronic liver disease in absence of any other identifiable cause of renal failure. It is primarily a diagnosis of exclusion. Despite of good pathophysiological understanding and better available therapeutic options for management of hepatorenal syndrome, it is still associated with significant morbidity and mortality. Liver transplantation forms the cornerstone for its management. In this review article, we have attempted to assimilate and summarise the advances made in the previous decade with regards to pathophysiology, classification and management of this entity.

Lack of association between Glu298Asp polymorphism and coronary artery disease in North Indians.

Nitric Oxide (NO) is an important molecule carrying number of different functions in humans. Published studies suggest that it may inhibit several key steps involved in the pathogenesis of atherosclerosis. Inhibition or reduction of NO due to Glu298Asp polymorphism may accelerate atherosclerosis. The aim of this study was to determine whether Glu298Asp polymorphism is implicated in the pathogenesis of coronary artery disease (CAD) among North Indian population from the state of Uttar Pradesh, India. We selected 253 CAD patients and 174 healthy, normotensive, non-diabetic controls, which were matched for gender and ethnicity. The Glu298Asp (rs1799983) variant was detected by genotyping subjects, using a polymerase chain reaction followed by restriction fragment length polymorphism. There was no significant difference found in the genotypic and allelic frequencies between patients and controls. Our study indicated that Glu298Asp polymorphism does not play any critical role in the pathogenesis of CAD, at least in North Indian population.

Prophylactic use of gabapentin for prevention of succinylcholine-induced fasciculation and myalgia: a randomized, double-blinded, placebo-controlled study.

BACKGROUND: Succinylcholine is used for rapid-sequence induction of anesthesia. Fasciculations and myalgia are adverse effects. The pretreatment modalities prevent or minimize its adverse effects. AIMS: The present study is designed to evaluate the efficacy of gabapentin on the incidence of fasciculation and succinylcholine-induced myalgia. SETTINGS AND DESIGN: The study was conducted at a tertiary care teaching hospital in a randomized, double-blinded, placebo-controlled manner. MATERIALS AND METHODS: Patients of both genders undergoing laparoscopic cholecystectomy were randomly assigned to two groups. Patients in Group I (Gabapentin group) received 600 mg of gabapentin orally 2 h prior to surgery and patients in Group II (placebo group) received matching placebo. Anesthesia was induced with fentanyl 3 µg/kg, thiopentone 3-5 mg/kg and succinylcholine 1.5 mg/kg. All patients were observed and graded for fasciculations by a blinded observer and patients were intubated. Anesthesia was maintained with oxygen in air, sevoflurane and intermittent vecuronium bromide. After completion of surgery, neuromuscular blockade was reversed. A blinded observer recorded myalgia grade at 24 h. Patients were provided patient-controlled analgesia with fentanyl for postoperative pain relief. STATISTICAL ANALYSIS: Demographic data, fasciculation grade, fentanyl consumption, and myalgia grade were compared using student t test and test of proportions. RESULTS: The study included 76 American Society of Anesthesiologists' Grade I or II patients of either gender undergoing laparoscopic cholecystectomy. But only 70 patients completed the study. Results demonstrated that the prophylactic use of gabapentin significantly decreases the incidence and the severity of myalgia (20/35 vs. 11/35) (P<0.05) and decreases fentanyl consumption significantly in the study group (620+164 µg vs. 989+238 µg) (P<0.05) without any effects on the incidence and severity of fasciculations. CONCLUSIONS: Prophylactic use of gabapentin 600 mg in laparoscopic cholecystectomy decreases the incidence and severity of myalgia and fentanyl consumption.

Patterns and determinants of dyslipidaemia in 'Young' versus 'Not so Young' patients of coronary artery disease: a multicentric, randomised observational study in northern India.

AIMS: The aims of the study were to ascertain difference in lipid levels of 'Young' onset of coronary artery disease (CAD) (≤ 45 years) vs. 'Not so Young' onset of CAD (≥ 55 years) among north Indians and also to investigate determinants of 'dyslipidaemia' in CAD patients. METHODS: This was a prospective, multicentric, randomised, observational study carried in eight centres of UP, India. All blood investigations were performed employing a central laboratory. RESULTS: Out of a total 435 patients studied, 218 were in the 'young group' (YG) and 235 were in the 'Not so Young Group' (NSYG). Dyslipidaemia was more common in YG as evident by significantly higher levels of total cholesterol, triglycerides, low- and very low-density lipoprotein cholesterol as compared to NSYG. Diabetes, hypertension, urban lifestyle, and family history of CAD were found to be important determinants of dyslipidaemia in YG. CONCLUSION: We conclude that lipid levels among north Indians are significantly higher in younger patients with CAD when compared with elderly.

"Tinni" rice (Oryza rufipogon Griff.) production: an integrated sociocultural agroecosystem in eastern Uttar Pradesh of India.

This study reports how Traditional Ecological Knowledge (TEK) and informal cultural institutions have conserved key varieties of the wildgrowing rice, 'tinni' (red rice, or brownbeard rice, Oriza rufipogon Griff.), within the Bhar community of eastern Uttar Pradesh, India. The study was conducted, using conventional and participatory methods, in 10 purposively selected Bhar villages. Two distinct varieties of tinni ('tinni patali' and 'tinni moti') with differing habitats and phenotypic characters were identified. Seven microecosystems (Kari, Badaila, Chammo, Karmol, Bhainsiki, Bhainsala and Khodailia) were found to support these varieties in differing proportions. Tinni rice can withstand more extreme weather conditions (the highest as well as lowest temperatures and rainfall regimes) than the 'genetically improved' varieties of rice (Oriza sativa L.) grown in the region. Both tinni varieties are important bioresources for the Bhar's subsistence livelihoods, and they use distinctive conservation approaches in their maintenance. Bhar women are the main custodians of tinni rice agrobiodiversity, conserving tinni through an institution called Sajha. Democratic decision-making at meetings organized by village elders determines the market price of the tinni varieties. Overall, the indigenous institutions and women's participation seem to have provided safeguards from excessive exploitation of tinni rice varieties. The maintenance of tinni through cultural knowledge and institutions serves as an example of the importance of locally maintained crop varieties in contributing to people's resilience and food security in times of rapid social and environmental change.

A machine learning-based approach to determine infection status in recipients of BBV152 (Covaxin) whole-virion inactivated SARS-CoV-2 vaccine for serological surveys.

Data science has been an invaluable part of the COVID-19 pandemic response with multiple applications, ranging from tracking viral evolution to understanding the vaccine effectiveness. Asymptomatic breakthrough infections have been a major problem in assessing vaccine effectiveness in populations globally. Serological discrimination of vaccine response from infection has so far been limited to Spike protein vaccines since whole virion vaccines generate antibodies against all the viral proteins. Here, we show how a statistical and machine learning (ML) based approach can be used to discriminate between SARS-CoV-2 infection and immune response to an inactivated whole virion vaccine (BBV152, Covaxin). For this, we assessed serial data on antibodies against Spike and Nucleocapsid antigens, along with age, sex, number of doses taken, and days since last dose, for 1823 Covaxin recipients. An ensemble ML model, incorporating a consensus clustering approach alongside the support vector machine model, was built on 1063 samples where reliable qualifying data existed, and then applied to the entire dataset. Of 1448 self-reported negative subjects, our ensemble ML model classified 724 to be infected. For method validation, we determined the relative ability of a random subset of samples to neutralize Delta versus wild-type strain using a surrogate neutralization assay. We worked on the premise that antibodies generated by a whole virion vaccine would neutralize wild type more efficiently than delta strain. In 100 of 156 samples, where ML prediction differed from self-reported uninfected status, neutralization against Delta strain was more effective, indicating infection. We found 71.8% subjects predicted to be infected during the surge, which is concordant with the percentage of sequences classified as Delta (75.6%-80.2%) over the same period. Our approach will help in real-world vaccine effectiveness assessments where whole virion vaccines are commonly used.

Scranton Type V Osteochondral Defects of Talus: Does one-stage Arthroscopic Debridement, Microfracture and Plasma Rich in Growth Factor cause the Healing of Cyst and Cessation of Progression to Osteoarthritis?

INTRODUCTION: The study was conducted to evaluate the efficacy of arthroscopic debridement, microfracture and plasma rich in growth factor (PRGF) injection in the management of type V (Scranton) osteochondral lesions of talus and its role in healing the subchondral cyst and cessation of progression of ankle osteoarthritis. MATERIAL AND METHODS: This is a prospective case series conducted on patients who were diagnosed with type V osteochondral lesions of talus. All the cases were treated with arthroscopic debridement, microfracture, and PRGF injections. The patients were evaluated for the healing of subchondral cysts and progression of osteoarthritis with radiography (plain radiographs and computerised tomography Scan). Also, the patients' outcome was evaluated with Quadruple Visual Analogue Scale, Ankle Range of Motion, Foot and Ankle Disability Index, Foot and Ankle Outcome Instrument and a Satisfaction Questionnaire. RESULTS: Five male patients underwent arthroscopic debridement, microfracture and PRGF injection for type V osteochondral lesion of talus. The mean age of patients was 27.4 years (19-47 years). All the patients gave history of minor twisting injury. Subchondral cyst healing was achieved in all patients by six months post-surgery. However, four out of five patients had developed early osteoarthritic changes of the ankle by their last follow-up [mean follow-up 29 months (ranged 15-36 months)]. Despite arthritic changes, all the patients reported 'Good' to 'Excellent' results on satisfaction questionnaire and Foot and Ankle Disability Index and could perform their day to day activities including sports. CONCLUSION: Arthroscopic debridement, microfracture, and PRGF causes healing of the subchondral cyst but does not cause cessation of progression to osteoarthritis of ankle in type V osteochondral defects of talus. However, despite progress to osteoarthritis, patient satisfaction post-procedure is good to excellent at short-term follow-up.

DNRA: A short-circuit in biological N-cycling to conserve nitrogen in terrestrial ecosystems.

This paper reviews dissimilatory nitrate reduction to ammonium (DNRA) in soils - a newly appreciated pathway of nitrogen (N) cycling in the terrestrial ecosystems. The reduction of NO3- occurs in two steps; in the first step, NO3- is reduced to NO2-; and in the second, unlike denitrification, NO2- is reduced to NH4+ without intermediates. There are two sets of NO3-/NO2- reductase enzymes, i.e., Nap/Nrf and Nar/Nir; the former occurs on the periplasmic-membrane and energy conservation is respiratory via electron-transport-chain, whereas the latter is cytoplasmic and energy conservation is both respiratory and fermentative (Nir, substrate-phosphorylation). Since, Nir catalyzes both assimilatory- and dissimilatory-nitrate reduction, the nrfA gene, which transcribes the NrfA protein, is treated as a molecular-marker of DNRA; and a high nrfA/nosZ (N2O-reductase) ratio favours DNRA. Recently, several crystal structures of NrfA have been presumed to producee N2O as a byproduct of DNRA via the NO (nitric-oxide) pathway. Meta-analyses of about 200 publications have revealed that DNRA is regulated by oxidation state of soils and sediments, carbon (C)/N and NO2-/NO3- ratio, and concentrations of ferrous iron (Fe2+) and sulfide (S2-). Under low-redox conditions, a high C/NO3- ratio selects for DNRA while a low ratio selects for denitrification. When the proportion of both C and NO3- are equal, the NO2-/NO3- ratio modulates partitioning of NO3-, and a high NO2-/NO3- ratio favours DNRA. A high S2-/NO3- ratio also promotes DNRA in coastal-ecosystems and saline sediments. Soil pH, temperature, and fine soil particles are other factors known to influence DNRA. Since, DNRA reduces NO3- to NH4+, it is essential for protecting NO3- from leaching and gaseous (N2O) losses and enriches soils with readily available NH4+-N to primary producers and heterotrophic microorganisms. Therefore, DNRA may be treated as a tool to reduce ground-water NO3- pollution, enhance soil health and improve environmental quality.

Patient controlled sedation during central neuraxial anesthesia.

BACKGROUND: Patient controlled sedation (PCS) gives liberty to patients to choose the time of sedative administration to attain a desired level of comfort. AIMS: The PCS use was evaluated in patients during surgery under central neuraxial blockade. SETTINGS AND DESIGN: Prospective, cross-sectional, clinical study on consecutive patients in a tertiary care university hospital. MATERIALS AND METHODS: PCS technique, using propofol (1%) 2 ml in 2 min was used in 160 adult patients undergoing urologic procedures under central neuraxial block. We observed the time to first PCS activation by patient, duration of surgery, propofol dose, sedation score, hemodynamic stability, patient's acceptability, and the factors correlating with the PCS use. STATISTICAL ANALYSIS USED: Non-parametric two-tailed Pearson's test, univariate correlation analysis for the factors favoring PCS use followed by multivariate logistic regression analysis amongst correlating factors. RESULTS: In our cohort, the majority (83%) of the patients activated PCS during surgery under central neuraxial blocks at median time of 30 min and (17%) did not activate PCS. Female patients activated sedation earlier (median 15 min) than male patients (median 30 min). All patients were hemodynamically stable and without significant side effects. Multivariate analysis showed that sedative use significantly ( P < 0.05) correlated with female gender (odds ratio-3.54 [IR-2.64 to 4.73]) and prolonged surgery (>90 min). Majority (91%) of patients rated PCS technique excellent to good. CONCLUSIONS: PCS was very well accepted by patients during central neuraxial block. Propofol regimen (2 ml in 2 min) in PCS was safe, as it caused neither apnea nor significant hypotension.

Study to Test and Operationalize Preventive Approaches for CKD of Undetermined Etiology in Andhra Pradesh, India.

INTRODUCTION: High prevalence of chronic kidney disease (CKD) not associated with known risk factors has been reported from coastal districts of Andhra Pradesh. The Study to Test and Operationalize Preventive Approaches for Chronic Kidney Disease of Undetermined Etiology in Andhra Pradesh (STOP CKDu AP) aims to ascertain the burden (prevalence and incidence) of CKD, the risk factor profile, and the community perceptions about the disease in the Uddanam area of Andhra Pradesh. METHODS: Study participants will be sampled from the Uddanam area using multistage cluster random sampling. Information will be collected on the demographic profile, occupational history, and presence of conventional as well as nonconventional risk factors. Glomerular filtration rate (GFR) will be estimated using the Chronic Kidney Disease Epidemiology Collaboration equation, and proteinuria will be measured. All abnormal values will be confirmed by repeat testing after 3 months. Cases of CKD not associated with identified etiologies will be identified. Biospecimens will be stored to explore future hypotheses. The entire cohort will be followed up every 6 months to determine the incidence of CKD and to identify risk factors for decline in kidney function. Qualitative studies will be performed to understand the community perceptions and expectations with respect to the interventions. IMPLICATIONS: CKD is an important public health challenge in low- and middle-income countries. This study will establish the prevalence and determine the incidence of CKD not associated with known risk factors in a reported high-burden region, and will provide insights to help design targeted health systems responses. The findings will contribute to the policy development to tackle CKD in the region and will permit international comparisons with other regions with similar high prevalence.