Application of student's t-test, analysis of variance, and covariance

Student's t test (t test), analysis of variance (ANOVA), and analysis of covariance (ANCOVA) are statistical methods used in the testing of hypothesis for comparison of means between the groups. The Student's t test is used to compare the means between two groups, whereas ANOVA is used to compare the means among three or more groups. In ANOVA, first gets a common P value. A significant P value of the ANOVA test indicates for at least one pair, between which the mean difference was statistically significant. To identify that significant pair(s), we use multiple comparisons. In ANOVA, when using one categorical independent variable, it is called one-way ANOVA, whereas for two categorical independent variables, it is called two-way ANOVA. When using at least one covariate to adjust with dependent variable, ANOVA becomes ANCOVA. When the size of the sample is small, mean is very much affected by the outliers, so it is necessary to keep sufficient sample size while using these methods.

Comparison of ranibizumab alone versus ranibizumab with targeted retinal laser for branch retinal vein occlusion with macular edema

Purpose: To determine the effect of ultra-widefield fluorescein angiography (UWFFA)-guided targeted retinal photocoagulation (TRP) in branch retinal vein occlusion (BRVO) with macular edema after intravitreal Ranibizumab (RBZ). Methods: 33 eyes of 32 treatment naïve patients diagnosed as BRVO with macular edema were prospectively randomized to 0.5 mg Ranibizumab only (RBZ group) (n = 17) or Ranibizumab with UWFFA-guided laser (RBZ + TRP group) (n = 16). Both groups received three injections at monthly intervals and PRN henceforth. RBZ + TRP group additionally underwent UWFFA-guided TRP of peripheral capillary nonperfusion areas 1 week post injection. Outcome measures included improvement in visual acuity, central subfoveal thickness (CST), and the number of injections required with a minimum follow-up of 9 months. Results: Both groups showed significant improvement in mean BCVA (25.7 ± 8.19 letters, P < 0.001 vs. 23.38 ± 7.56 letters, P < 0.001; in RBZ and RBZ + TRP group, respectively) and reduction in mean central subfoveal thickness (379.12 ± 242.7 ?m, P < 0.001 vs. 253.75 ± 137.9 ?m, P < 0.001 in RBZ and RBZ + TRP group, respectively) at 9 months. The number of injections in the RBZ group (5.76 ± 1.3) was significantly greater than RBZ + TRP (4.06 ± 0.99) (P < 0.001). Both groups had significant improvement in contrast sensitivity and mean deviation on visual fields; however, the difference between the groups was not significant (P = 0.62 and P = 0.79, respectively). Conclusion: UWFFA-guided TRP reduced the number of injections of Ranibizumab in patients having BRVO with macular edema, while maintaining similar benefits in the improvement of BCVA, central subfoveal thickness without deleterious effect on the visual field, and contrast sensitivity.

Choroidal thickness in normal Indian eyes using swept-source optical coherence tomography

Purpose: The purpose of this study is to provide normative database for subfoveal choroidal thickness in Indian eyes using swept-source optical coherence tomography. Methods: This is a cross-sectional study based at a tertiary eye care center in Northern India. Two hundred and thirty eight eyes of 119 healthy subjects were examined in terms of axial length, spherical equivalent, and choroidal thickness. Inclusion criteria included age 19� years, no retinal or choroidal disorder, and patients with clear media and good fixation. Patients with high hypermetropia (>4 D) or myopia (>6 D) or any systemic disease likely to affect choroidal thickness were excluded. Twelve radial line scans were obtained centered on the fovea that were used to calculate choroidal and retinal thickness in 9 early treatment diabetic retinopathy study (ETDRS) zones. Results: The mean age of all the subjects was 28.70 � 11.28 years; mean axial length was 23.63 � 1.96 mm, and mean spherical equivalent was ? 0.92 � 3.08 D. The mean subfoveal choroidal thickness was 299.10 � 131.2 ? and mean foveal thickness was 239.92 � 48.16 ?. A negative correlation was found between subfoveal choroidal thickness and age (r = ?0.0961, P = 0.1392) and axial length (r = ?0.3166, P < 0.001). A statistically significant positive correlation was found between subfoveal choroidal thickness and refractive error (r = 0.2393, P = 0.0002). Conclusion: This study provides normative database for subfoveal choroidal thickness and foveal thickness using swept-source optical coherence tomography. The choroidal thickness measured with swept-source platform is slightly higher than that reported with spectral domain platforms.

Descriptive statistics and normality tests for statistical data

Descriptive statistics are an important part of biomedical research which is used to describe the basic features of the data in the study. They provide simple summaries about the sample and the measures. Measures of the central tendency and dispersion are used to describe the quantitative data. For the continuous data, test of the normality is an important step for deciding the measures of central tendency and statistical methods for data analysis. When our data follow normal distribution, parametric tests otherwise nonparametric methods are used to compare the groups. There are different methods used to test the normality of data, including numerical and visual methods, and each method has its own advantages and disadvantages. In the present study, we have discussed the summary measures and methods used to test the normality of the data.

Detection of Mycobacterium avium subsp. Paratuberculosis in bovine faecal samples by Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) TaqMan Assay

Mycobacterium avium subsp. paratuberculosis, the causative agent of Johne’s disease is a degenerative chronic granulomatous disease of bovines. In the present study, quantitative real time polymerase chain reaction (qRT-PCR) using TaqMan chemistry targeting the IS900 sequence of Mycobacterium avium subsp. paratuberculosis (MAP) was employed for the molecular diagnosis of the disease in bovine faecal samples. Out of 200 bovine faecal samples processed, 7 samples were tested as positive by IS900 qRT-PCR. The sensitivity limit of detection of MAP DNA in faecal samples by qRT-PCR TaqMan assay was found to be 0.05pg. No amplification was observed in other Mycobacterial spp. viz. M. phlei, M. smegmatis, M. intracellulare and M. kansasii.

Chronic Nonmodulated Microwave Radiations in Mice Produce Anxiety-like and Depression-like Behaviours and Calcium- and NO-related Biochemical Changes in the Brain

The present study was aimed to investigate behavioural and biochemical effects of chronic exposure of amplitude modulated and non-modulated microwave radiation on laboratory mice. Chronic microwave exposures were executed with 2.45 GHz of either modulated (power density, 0.029 mW/cm²; specific absorption rate, 0.019 W/Kg with sinusoidal modulation of 400 Hz) or nonmodulated continuous sinusoidal wave (power density, 0.033 mW/cm²; specific absorption rate, 0.023 W/Kg) for 2 hrs daily for 1 month. Mice subjected to non-modulated microwave exposure had significantly increased acetylcholinesterase activity and increased intracellular calcium and nitric oxide levels in the cerebral cortex and hippocampus, and also had increased glucose and corticosterone levels in blood compared to control mice. These non-modulated microwave-exposed mice exhibited anxiety-like and depression-like behaviours. In contrast, mice exposed to modulated microwave for the same period did not show such changes in concomitant biochemical and behavioural analyses. These results suggest that chronic non-modulated microwave, but not modulated microwave, radiation may cause anxiety-like and depression-like behaviours and calcium- and NO-related biochemical changes in the brain.

Derivative Spectrophotometric Methods for the Determination of Zolpidem Tartrate in Tablets.

Two simple, precise and accurate first derivative spectrophotometric methods were developed for the determination of Zolpidem Tartrate in pharmaceutical formulations in phosphate buffer pH 6.8 and acetate buffer pH 4.0. Beer’s law was obeyed over the concentration range 0.5-20 μg/ml in both phosphate buffer (pH 6.8) (Method A) and acetate buffer (pH 4.0) (Method B). The regression equations were found to be y = 0.101x+0.012 (r2 = 0.999) and y = 0.064x+0.009 (r2 = 0.999) in Method A and B respectively. The % RSD in precision studies was found to be 0.28-0.69 (Intra-day) and 0.31-0.73 (Inter-day) for Method A and 0.25-0.82 (Intra-day) and 0.26-0.57 (Inter-day) for Method B respectively. The % RSD in accuracy studies was also found to be 0.14-0.19 (Method A) and 0.18-0.23 (Method B) with percentage recovery 98.67-99.78 and 98.56-99.83 Method A and B respectively.

Global positioning system: A new tool to measure the distribution of anemia and nutritional status of children (5-10 years) in a rural area in south India.

Global positioning system (GPS) is a satellite-based navigation system that is of late being used in health care. Objectives: The aims of the study were to describe the geographical distribution and assess the prevalence of anemia and malnutrition in children aged 5-10 years with GPS. Subjects and Methods: This exploratory study was conducted over a period of 2 months in the rural field practice area of a medical college situated in Bangalore during June-July 2012. Children aged 5-10 years were the study subjects. Results: GPS was used for describing the geographical distribution of anemia and nutrition status on the Google earth map. The prevalence of anemia in the study subjects was 8.7%. The prevalence of underweight, stunting, thinness, and severe thinness among the study subjects was 52.8%, 28.5%, 23.5%, and 29.1%, respectively; however, overweight and obesity were observed only in 0.9% and 1.2% of the study subjects, respectively. Conclusion: GPS was easy to use and was able to demonstrate the actual distribution of morbidity at the household level in the rural area.

Molecular cloning, purification and characterization of thermostable -1,3-1,4 glucanase from Bacillus subtilis A8-8.

A gene encoding a -1,3-1,4-glucanase (CelA) belonging to family 5 of glycoside hydrolases was cloned and sequenced from the Bacillus subtilis A8-8. The open-reading-frame of celA comprised 1499 base pairs and the enzyme was composed of 500 amino acids with a molecular mass of 55 kDa. The recombinant -1,3-1,4 glucanase was purified by GST-fusion purification system. The pH and temperature optima of the enzyme were 8.0 and 60oC, respectively. The enzyme was stable within pH 6.0-9.0. It was stable up to 60oC and retained 30% of its original activity at 70oC for 60 min. It hydrolyzed lichenan, CMC, xylan, laminarin, avicel and pNPC, but was inactive towards cellobiose. The enzyme activity was markedly activated by Co2+ and Mn2+, but was strongly inactivated by Fe3+. The truncated gene, devoid of cellulose-binding domain (CBD) showed 60% of activity and bound to avicel.

Prevalence of hepatitis C virus (HCV) coinfection in HIV infected individuals in south India and characterization of HCV genotypes.

PURPOSE: To determine anti-HCV antibodies and genomic subtype of HCV in 1487 confirmed human immunodeficiency virus (HIV) positive samples. METHODS: A total of 1487 confirmed HIV-positive samples were tested for anti-HCV antibodies by using a third generation ELISA kit (Ortho 3.0) and by RT PCR for HCV. HIV and HCV coinfected samples were selected for HCV genotyping by RFLP and subtyping with NS5-type specific primers. RESULTS: A total of 1487 HIV-infected serum samples were screened for HCV infection, of which, a 1443 (97.04%) were negative and 45 (3.02%) were coinfected. HIV-HCV coinfection was predominant in the age group 41-50 years (51.1%). HCV genotyping and subtyping was done for the 45 HCV RNA-positive specimens of which genotype 1 was observed in 31 (68.8%) and genotype 3 was observed in 14 (31.1%) subjects. Further subtyping analysis showed the genotype 1b in 23 (51.1%), 1a in eight (17.7%), 3a in 10 (22.2%) and 3b in four (8.8%) subjects. CONCLUSION: HIV and HCV seroprevalence is higher in South India, and the most prevalent genotype in coinfection was genotype 1b.

Epidemiological study of ocular trauma in an urban slum population in Delhi, India.

PURPOSE: To study the epidemiology and clinical profile of victims of ocular trauma in an urban slum population. MATERIALS AND METHODS: This cross-sectional study, conducted on 500 families each in three randomly selected urban slums in Delhi, collected demographic data for all members of these families, and clinical data for all those who suffered ocular trauma at any time, that required medical attention. Data was managed on SPSS 11.0. RESULTS: Of 6704 participants interviewed, 163 episodes of ocular trauma were reported by 158 participants (prevalence = 2.4%, confidence interval = 2.0 to 2.7) Mean age at trauma was 24.2 years. The association between the age of participants and the history of ocular trauma was significant ( P < 0.001), when adjusted for sex, education and occupation. Males were significantly more affected. Blunt trauma was the commonest mode of injury (41.7%). Blindness resulted in 11.4% of injured eyes ( P = 0.028). Of 6704 participants, 1567 (23.4%) were illiterate, and no association was seen between education status and trauma, when adjusted for sex and age at injury. A significant association was noted between ocular trauma and workplace (Chi-square = 43.80, P < 0.001), and between blindness and place (Chi-square = 9.98, P = 0.041) and source (Chi-square = 10.88, P = 0.028) of ocular trauma. No association was found between visual outcome and the time interval between trauma and first consultation (Chi-square = 0.50, P = 0.78), between receiving treatment and the best corrected visual acuity (Chi-square = 0.81, P = 0.81), and between the person consulted and blinding ocular trauma (Chi-square = 1.88, P = 0.170). CONCLUSION: A significant burden of ocular trauma in the community requires that its prevention and early management be a public health priority.

Effect of DENA induced hepatocarcinogenesis on neuroendocrine levels in male rats.

Hepatocarcinogenesis was induced in Sprague Dawley rats by injecting diethylnitrosamine (DENA); 150 mg/kg body weight, ip, a well known liver carcinogen and a mutagenic agent. Concurrent with the induction of hepatocarcinoma, psychological stress was also elicited from the changes in brain neurotransmitters. Noradrenaline and dopamine, the neurotransmitters of sympathetic system were estimated from the whole brain and corresponding hormones T3, T4 and prolactin were estimated from the blood of such rats. The neuroendocrine cascade and the marker enzyme gamma glutamyl transferase were estimated at 7, 14, 21 and 30 weeks. A direct relationship between noradrenaline, T3 and T4 and a reciprocal relationship between dopamine and prolactin were observed, which may be correlated to the carcinogenic effect of DENA.

Release of copper from CuT 380A co-incubated with human semen and its effect on sperm function in vitro.

Release of copper and its effect on functional integrity of human sperms in vitro were assessed following co-incubation of semen with CuT 380A. After 30 min of incubation with semen, release of copper ions from CuT 380A was found to be 9.2 to 40 times higher compared to control incubations with PBS. Sperm function tests, when simultaneously performed following loss of motility in sperms (>95%) after 120 min of copper exposure, depicted a significant (P<0.001) reduction in sperm viability and hypo-osmotic swelling (HOS) response. However, the affected sperm populations revealed no significant alterations in other functional tests like acrosomal status or nuclear chromatin decondensation. It is therefore concluded that the high release of copper from CuT 380A drastically lowers sperm motility. viability and HOS response but only marginally affects the acrosome status or nuclear chromatin condensation in short term incubations.

Low prevalence of hepatitis B virus and hepatitis C virus co-infection in patients with human immunodeficiency virus in Northern India.

AIM: To study the prevalence of HBV and HCV co-infection in patients with HIV attending a referral hospital in Northern India. METHODS AND MATERIAL: The study cohort included six hundred and twenty consecutive HIV infected patients who were studied for co-infection with HBV/HCV or both. It included four hundred and seventy two male and one hundred and forty eight female patients between the age group 25-50 years. HBV and HCV infection was diagnosed by ELISA. Other routine investigations were also done. RESULTS: Out of a total of 620 consecutive HIV infected patients studied, HBV co-infection was detected in 14/ 620 (2.25%) patients and HCV co-infection in 10/620 (1.61%) patients and dual co-infection (HBV/HCV) in 1/620(0.16%). The mode of transmission of HBV was sexual contact in all (100%), while for HCV it was sexual contact in 5 patients (50%), blood transfusion in 4 patients (40%) and intravenous drug use (IDU) in 1 patient (10%). CONCLUSION: The prevalence of co-infection with HBV/HCV is much lower in our study population as compared to that reported in Western literature.

Ophthalmic regional block

Cataract surgery is the commonest ophthalmic surgical procedure and a local anaesthetic technique is usually preferred but the provision of anaesthesia in terms of skills and resources varies worldwide. Intraconal and extraconal blocks using needles are commonly used. The techniques are generally safe but although rare, serious sight- and life-threatening complications have occurred following the inappropriate placement of needles. Sub-Tenon's block was introduced as a safe alternative to needle techniques but complications have arisen following this block as well. Currently, there is no absolutely safe ophthalmic regional block. It is essential that those who are involved in the care of these patients have a thorough knowledge of the techniques used. This review article outlines the relevant anatomy, commonly used techniques and their safe performance and perioperative care.

Retrobulbar alcohol injection for orbital pain relief under difficult circumstances: a case report

<p><b>INTRODUCTION</b>A case is presented of a patient with severe and chronic pain in the orbital region, which was relieved by retrobulbar injection of absolute alcohol. The management of chronic pain in the orbital region has received little attention and the literature is reviewed.</p><p><b>CLINICAL PICTURE</b>A 52-year-old man with adenoid cystic carcinoma of the maxillary sinus was suffering from severe pain, especially in the left orbital region. There was also pain from ocular exposure and compression caused by the tumour. Magnetic resonance imaging (MRI) revealed spread of tumour to both orbits, particularly on the left. Multiple debulking surgery and various treatment modalities offered no relief from his pain.</p><p><b>TREATMENT</b>A single retrobulbar injection of 2 mL of absolute alcohol, was placed into the putative orbital apex.</p><p><b>OUTCOME</b>As a consequence of the injection, he had complete resolution of his pain in the 6 months prior to his death.</p><p><b>DISCUSSION</b>Retrobulbar injection of alcohol offers effective pain relief in certain specific conditions characterised by chronic orbital pain when other treatments do not help.</p><p><b>CONCLUSION</b>We have demonstrated that the retrobulbar technique still has a place in our armamentarium.</p>

Prevalence of hypertension in psychiatric disorders.

OBJECTIVE: To study the prevalence of hypertension in our cases with psychiatric disorders and to study if the prevalence is higher in the cases with psychiatric disorders. METHODS: Four hundred twenty two cases with various psychiatric disorders attending the Outpatient Department of Psychiatry of our hospital were studied. Detailed clinical evaluation was done in all the cases. Blood pressure was recorded in the sitting position and mean of three readings was taken. Diagnosis and grading of hypertension was done according to the JNC V recommendations. Psychiatric disorders were diagnosed according to DSM IV criteria. RESULTS: Mean age of the cases was 36.3 years. Prevalence of hypertension in the cases was 7.1%. Prevalence in male and female cases were 7.2% and 7.0%, respectively. Prevalence of hypertension in various age groups was 20-39 years--1.48%, 40-60 years--24.4%, > 60 years--33.3%. CONCLUSION: The overall prevalence of hypertension in our cases with psychiatric disorders was 7.1% which was not higher than the reported prevalence of hypertension in our general population.