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K N Prasad

Publications and source records attributed to K N Prasad.

At least 19 recordsLinked to original sources
PubMed2006

Diffusion tensor imaging in polymicrogyria: a report of three cases.

INTRODUCTION: Polymicrogyria (PMG), a neuronal migration disorder, commonly manifests as a seizure disorder. The aim of this study was to look for the abnormalities in the underlying white matter using diffusion tensor imaging (DTI) that appeared normal on conventional magnetic resonance imaging (MRI) in patients with PMG. METHODS: DTI was performed in three patients with PMG and eight age- and sex-matched healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated for the cortex and adjoining subcortical white matter in both controls and patients. RESULTS: We observed a significantly decreased mean FA value with no significant change in the MD value in subcortical white matter underlying polymicrogyric cortex (FA = 0.23+/-0.04, MD = 1.0+/-0.05 x 10(-3) mm(2)/s) as compared to both contralateral (FA = 0.32+/-0.04, MD = 1.0+/-0.05 x 10(-3) mm(2)/s) and normal control (FA = 0.32+/-0.04, MD = 1.0+/-0.06 x 10(-3) mm(2)/s) white matter. Significantly increased MD and decreased FA values were also observed in the polymicrogyric cortex (FA = 0.08+/-0.01, MD = 1.2+/-0.10 x 10(-3) mm(2)/s) as compared to normal contralateral (FA = 0.12+/-0.04, MD = 1.1+/-0.09 x 10(-3) mm(2)/s) and normal control (FA = 0.12+/-0.01, MD = 1.1+/-0.09 x 10(-3) mm(2)/s) cortex. CONCLUSION: Significantly decreased FA values with no change in MD values in the subcortical white matter subjacent to polymicrogyric cortex reflect microstructural changes in the white matter probably due to the presence of ectopic neurons.

Adult↗
PubMed2006

Assessment of white matter damage in subacute sclerosing panencephalitis using quantitative diffusion tensor MR imaging.

BACKGROUND AND PURPOSE: Subacute sclerosing panencephalitis (SSPE), a rare progressive degenerative disease, is caused by persistent infection with a defective measles virus. The correlation between the clinical staging and MR imaging is usually poor. The aim of the study was to investigate the role of diffusion tensor imaging (DTI) in the early detection of white matter damage in SSPE in the presence of normal findings on conventional imaging. METHODS: DTI was performed in 21 patients in stage II SSPE and 10 age/sex-matched healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated in the periventricular white matter, corpus callosum, and posterior limb of the internal capsule in patients with normal and abnormal findings on conventional imaging as well as healthy controls. RESULTS: The patients were grouped into those with normal (n = 11) and abnormal (n = 10) findings on conventional imaging for the purpose of quantitative DTI analysis. Abnormal- and normal-appearing white matter on T2-weighted images showed significantly decreased FA values in all the regions compared with those in healthy controls. MD values were significantly increased in the periventricular white matter region of the frontal and parietooccipital lobe in patients with normal as well as abnormal findings on conventional imaging compared with those in healthy controls. CONCLUSION: DTI detects early white matter abnormalities that may have significant therapeutic implication, even in the presence of normal findings on conventional imaging, in patients with SSPE.

Adolescent↗
PubMed2005

Rationale for using multiple antioxidants in protecting humans against low doses of ionizing radiation.

Health risks of low doses of ionizing radiation (10 cGy or less) may not be accurately estimated in humans by epidemiological study or mathematical modelling because of several inherent confounding factors including environmental, dietary and biological variables that cannot be accounted for in any radio-epidemiological study. In addition, the expression of radiation-induced damage in humans not only depends upon total dose, dose rate, linear energy transfer (LET), and fractionation and protraction of total doses, but also on repair mechanisms, bystander effects, and exposure to chemical carcinogens, tumour promoters and other toxins. It also depends upon the levels of anti-carcinogenic and anti-tumour promoting agents. Low doses of ionizing radiation should not be considered insignificant with regard to increasing the incidence of somatic mutations (neoplastic and non-neoplastic diseases) and heritable mutations in humans owing to its interaction with other toxins that can enhance damage produced by irradiation. It is very prudent to continue to support the well-established radiobiological concept that no radiation dose can be considered completely safe, and that all efforts must be made to reduce both the radiation dose and biological damage, no matter how small that damage might be, without sacrificing the benefits of radiation. Based on the results of many scientific experiments, formulations containing multiple antioxidants for biological protection against radiation damage in humans can be developed, and this strategy together with the existing physical concept of radiation protection, should further reduce potential risks of low doses of ionizing radiation in humans.

Animals↗
PubMed2004

Suboptimal chlorine treatment of drinking water leads to selection of multidrug-resistant Pseudomonas aeruginosa.

The present study was undertaken to investigate the spectrum of bacteria present in the River Gomti water before and after chlorination for drinking purposes. We observed that the strains of Pseudomonas aeruginosa that survived chlorination on three out of seven occasions were resistant to almost all the antibiotics tested. The chlorine-resistant bacteria had mucoid colonies and grew better at 24 degrees C. All attempts to isolate the plasmid responsible for chlorine resistance were unsuccessful. Laboratory experiments using different strains of the P. aeruginosa in distilled water showed that only the resistant strain survived chlorine treatment at a dose of < or =500 microg/L. Similar results were obtained when water collected from seven different sites on the River Gomti was treated with graded doses of chlorine. At the higher dose of chlorine, all the bacteria died in 30 min, whereas with lower doses all the bacteria survived. The present study underscores the importance of measuring water chlorine concentrations to assure they are sufficiently high to remove pathogenic bacteria from drinking water. To our knowledge, this is the first report in the literature of the selection of multidrug-resistant bacteria by suboptimal chlorine treatment of water.

Anti-Bacterial Agents↗
PubMed2004

Fungal peritonitis in patients on continuous ambulatory peritoneal dialysis: a single centre Indian experience.

BACKGROUND: Fungal peritonitis (FP) is a serious complication in patients on continuous ambulatory peritoneal dialysis (CAPD). We reviewed our FP cases to analyse the causative agents and possible risk factors in relation to FP and its outcome and mortality. METHODS: Records of all FP cases were reviewed. FP was diagnosed based on effluent cell count and positive fungal culture in suitable media. RESULTS: Between October 1993 and November 2001, 261 patients underwent CAPD. FP was detected in 28 patients, one episode in each patient (14.3% of the total peritonitis episodes). Candida species and dematiaceous fungi+/-Candida species were responsible for 89.3 and 10.7% of episodes, respectively. Patients with preceding bacterial peritonitis (BP) developed FP more frequently (25.6%) than de novo cases (2.9%) (P<0.0001) and lower proportion of them continued CAPD (8.6% vs. 60%; P=0.007). Mortality in patients having abdominal pain with and without fever, and catheter in situ was significantly higher than in those patients who did not have these risk factors (9/11 vs. 6/17, P=0.01; 13/17 vs. 2/11, P=0.003; 6/6, vs. 9/22, P=0.01, respectively). CONCLUSIONS: Higher proportion of our patients had FP; preceding BP was a significant risk factor for development of FP and technique failure. Abdominal pain+/-fever in patients and catheter in situ were identified as risk factors associated with mortality.

Female↗
PubMed2004

Infectious meningitis: prospective evaluation with magnetization transfer MRI.

The study was performed with the aim of prospectively characterizing infectious meningitis of different aetiology using magnetization transfer (MT) MRI. Spin-echo (SE) T(1), T(2) and pre- and post-contrast T(1) weighted MT images in 100 patients with aetiologically proven meningitis were evaluated for the visibility and enhancement of the meninges on pre- and post-contrast T(1) weighted MT images, respectively. The MT ratio (MTR) was calculated from the thickened meninges in tuberculous meningitis. In addition, the percentage difference in the mean signal intensity (SI) of the meninges and adjacent brain parenchyma was calculated and compared between different groups using 2-tailed student's t-test. T(1) weighted MT images were highly sensitive (96%) in the detection of abnormal meningeal enhancement. Meninges were visible on pre-contrast T(1) weighted MT images only in patients with tuberculous meningitis. The MTR from meninges in tuberculous infection was 19.10+/-1.02, and the percentage difference in the mean SI of the meninges and the adjacent T(2) normal brain parenchyma was significantly higher (p<0.05) in the tuberculous group compared with that in the non-tuberculous group. MT MRI is an important technique for the detection and characterization of infectious meningitis of different aetiology. Visibility of the meninges on pre-contrast T(1) weighted MT images may be considered highly suggestive of tuberculous meningitis.

Adolescent↗
PubMed2003

Defects in cAMP-pathway may initiate carcinogenesis in dividing nerve cells: a review.

The mechanisms of carcinogenesis in nervous tissues are not well understood. It is now established that adenosine 3,',5'-cyclic monophosphate (cAMP)-pathway plays a crucial role in initiating differentiation in transformed and embryonic cells of neuronal and glial origin. Therefore, we propose that defects in the cAMP-pathway may initiate the first phase of carcinogenesis (immortalization). Subsequent genetic abnormalities in oncogenes, anti-oncogenes or other cellular genes individually or in combination may lead to transformation (cancer phenotype). This hypothesis is derived from the fact that an elevation of the cAMP level in murine NB cells induces terminal differentiation in many of these cells in spite of the fact that they are highly aneuploid. Additional changes in cAMP-regulated genes responsible for initiating differentiation may make these cells resistant to cAMP or may make the cAMP-effect on differentiation reversible. Indeed, cAMP-resistant cells exist in NB cell populations, and the cAMP-effect on differentiation is reversible in glioma cells. Identification of genes that initiate, promote and maintain terminal differentiation and those which prevent differentiation following elevation of cAMP in NB cells may increase our understanding of the mechanisms of carcinogenesis. This review illustrates the following: (a) historical background leading to the discovery of cAMP as an inducer of differentiation in nerve cells; (b) identification of potential sites in cAMP-pathway that may play a crucial role in initiating the first phase of carcinogenesis (immortalization) and potential gene targets in immortalized cells whose alterations may cause neoplastic transformation of nerve cells. It is interesting to note that the cAMP pathway remains responsive to an elevated cAMP level in inducing differentiation in NB cells in spite of chromosomal anomalies and genetic changes associated with the maintenance of a cancer phenotype.

Adenylyl Cyclases↗
PubMed2003

Broad identification of bacterial type from pus by 1H MR spectroscopy.

BACKGROUND: Abscess formation is a common bacterial infection and requires an immediate antimicrobial approach for apposite treatment. Delay in patient treatment is usually a common feature, as the bacterial identification of clinical samples is based on the culture, which is a time-consuming exercise. The current study was aimed at developing an alternative technique with the potential for rapid bacterial group identification. MATERIALS AND METHODS: In the present study we performed ex vivo proton magnetic resonance spectroscopy of 40 pus samples collected from abscesses in different locations and the results have been retrospectively compared with the microorganism identified in the pus culture. In addition, the microbes obtained from the culture have been further subcultured and studied with magnetic resonance spectroscopy to identify the bacterial fingerprint in the pus sample seen on spectroscopy. RESULTS: On reviewing the spectra obtained from the various abscesses, they were found to be qualitatively similar for a particular bacterium. The similar spectral pattern of the pus with obligate aerobes/anaerobes and pure cultures of the same bacteria suggests its strict metabolism under in vivo and in vitro conditions, respectively. CONCLUSIONS: The characteristic metabolite pattern of obligate anaerobes may be used as a prototype for its rapid identification. This information may be of value for more appropriate clinical management of such cases.

Abscess↗
PubMed2003

Is neurocysticercosis a risk factor in coexistent intracranial disease? An MRI based study.

BACKGROUND: Previous reports have suggested that neurocysticercosis is associated with glioma and Japanese encephalitis, and that it is a risk factor for stroke. OBJECTIVE: To determine if neurocysticercosis has a significant association with, or is a risk factor for, coexistent pathologies such as Japanese encephalitis, glioma, abscess, tuberculoma, or infarction. SUBJECTS: 10 350 patients from the hospital population who underwent 1.5 T cranial magnetic resonance imaging during the previous 12 years were evaluated for the presence of neurocysticercosis and coexisting pathology. DESIGN: Retrospective cohort analysis. RESULTS: The prevalence of neurocysticercosis in cases with dual pathology was significantly less than in a control group (1.1% v 8.3%; z = 11.05; p < 0.001, power of test = 1). Neurocysticercosis lesions were less common (p < 0.05) in the different subgroups of coexistent pathology than in the control group except in the case of Japanese encephalitis, where the difference was non-significant (z = 0.69, p = 0.49). The relative risk was less than 1 in all subgroups except Japanese encephalitis, where it was 1.23. The location of neurocysticercosis lesions and the presence of perilesional oedema did not affect coexistent lesion location or severity on a particular side (p = 0.413 and 0.623 for location and perilesional oedema, respectively). When the above factors were analysed separately in patients with Japanese encephalitis, they also did not affect coexistent lesion location or severity (p = 0.659 and 0.548, respectively). CONCLUSIONS: The coexistence of neurocysticercosis and other lesions may be an incidental observation in a few patients referred from areas of high prevalence and endemicity. It appears unlikely that neurocysticercosis is a risk factor for other intracerebral pathology. The location of neurocysticercosis lesions and whether or not there is surrounding perilesional oedema do not appear to affect the location or severity of coexisting lesions.

Adolescent↗
PubMed2003

Candidaemia in patients of a tertiary health care hospital from north India.

BACKGROUND & OBJECTIVES: Candidaemia is an important cause of mortality in hospital settings. Limited information is available from India on nosocomial candidaemia. The objective of the present study was to isolate and identify yeasts from patients suspected to have nosocomial bloodstream infection (BSI) and to determine the carriage rate of Candida species, risk factors for acquisition of infection and mortality in this group of patients. METHODS: Blood samples from 4871 patients suspected to have BSI at least 48 h after admission were cultured following standard protocol to isolate and identify the pathogens. Clinical details, possible risk factors and outcome of all candidaemic patients were recorded and analysed. Samples of hand washings and throat gargles from these patients were also cultured to determine the carriage rate. Candida albicans isolated from patients and their carriage sites were genotyped by randomly amplified polymorphic DNA (RAPD) analysis to study strain relatedness. RESULTS: Twenty one patients with candidaemia were detected with mortality of 55 per cent. Candidaemia per 1000 admissions was 1.61. Isolation of non-C. albicans Candida species was significantly higher than C. albicans (14/21 vs 7/21: P < 0.05). Use of broad-spectrum antibiotics (43%), gastrointestinal surgery (23%), immunosuppressive therapy (23%), protein calorie malnutrition with parenteral hyperalimentation (23%) and neutropaenia (14%) were identified as probable risk factors. The seven C. albicans strains isolated from patients with BSI were typed into 6 genotypes. Yeast carriage rate among the patients was 71.4 per cent. C. albicans isolated from the hand, throat and blood of two patients had identical genotype. INTERPRETATION & CONCLUSION: BSI due to non-C. albicans Candida species is more common than C. albicans in our patients and candidaemia is associated with high mortality. RAPD appears to be a simple method to study strain relatedness for C. albicans. There is a need for early diagnosis and systematic surveillance to meet the challenges of nosocomial candidaemia.

Adolescent↗
PubMed2003

Cryptococcal infection in patients with clinically diagnosed meningitis in a tertiary care center.

A retrospective analysis of 326 clinically diagnosed cases with meningitis over a period of five-and-a-half years was carried out to determine the prevalence of cryptococcal infection, its associated risk factors and therapeutic outcome. Fifty-four (16.6%) patients with cryptococcal meningitis were identified by smear examination, culture and/or cryptococcal antigen latex agglutination test. Records of 45 cryptococcal meningitis patients were available; 18 (40%) of them were apparently healthy immunocompetent individuals, 13 (28.9%) had human immunodeficiency virus (HIV) infection, 9 (20%) were renal transplant recipients, 4 (8.9%) were diabetic and 1 (2.2%) had systemic lupus erythematosus. Ten (22.2%) patients died and 11 (24.4%) patients (all HIV-positive) left against medical advice. The present study indicates that cryptococcal infection is associated with high mortality. Presenting symptoms being indistinguishable from other causes of central nervous system infection, all patients with a clinical diagnosis of meningitis, irrespective of their immune status should be investigated for cryptococcal infection.

Adolescent↗
PubMed2002

Pros and cons of antioxidant use during radiation therapy.

Radiation therapy is one of the major treatment modalities in the management of human cancer. While impressive progress like more accurate dosimetry and more precise methods of radiation targeting to tumor tissue has been made, the value of radiation therapy in tumor control may have reached a plateau. At present, two opposing hypotheses regarding the use of antioxidants during radiation therapy have been proposed. One hypothesis states that supplementation with high doses of multiple micronutrients including high dose dietary antioxidants (vitamins C and E, and carotenoids) may improve the efficacy of radiation therapy by increasing tumor response and decreasing some of its toxicity on normal cells. The other hypothesis suggests that antioxidants (dietary or endogenously made) should not be used during radiation therapy, because they would protect cancer cells against radiation damage. Each of these hypotheses is based on different conceptual frameworks that are derived from results obtained from specific experimental designs, and thus, each may be correct within its parameters. The question arises whether any of these concepts and experimental designs can be used during radiation therapy to improve the management of human cancer by this modality. This review has analyzed published data that are used in support of each hypothesis, and has revealed that the current controversies can be resolved, if the results obtained from one experimental design are not extrapolated to the other. This review has also discussed the scientific rationale for a micronutrient protocol that includes high doses of dietary antioxidants (vitamin C, vitamin E succinate and natural beta-carotene) which can be used adjunctively with radiation therapy.

Animals↗
PubMed2002

UreC PCR based diagnosis of Helicobacter pylori infection and detection of cag A gene in gastric biopsies.

Polymerase chain reaction assay using ureC gene specific primers for the detection of Helicobacter pylori in gastric biopsy specimens from 116 dyspeptic patients was compared with other routine invasive diagnostic methods (culture, rapid urease test [RUT] and histology). In parallel, gastric biospy specimens from 54 patients and their corresponding Helicobacter pylori isolates were subjected to PCR with cagA targeting primers using standard protocols. Helicobacter pylori were detected in 53%, 43%, 48% and 50% of patients by PCR, RUT, culture and histological examination respectively. Based on histology and culture positive and at least three test positive result, 44 (37%), 46 (39%) and 26 (22%), and 56 (48%), 52 (44%) and 8 (6%) patients were classified as Helicobacter pylori positive, negative and indeterminate respectively. The sensitivity and specificity of PCR assay was the highest-95% and 100% when compared with both culture and histology positive, and at least any three positive results respectively. The result of cagA positivity in 54 gastric biopsy specimens and their corresponding Helicobacter pylori isolates were identical; 18 of 20 (90%) duodenal ulcer patients and 23 of 28 (82%) patients with chronic gastritis and 2 (40%) of 5 patients with portal hypertension and one gastric biopsy specimens from gastric cancer patients were found to be cagA positive. PCR-based method to detect Helicobacter pylori and the virulence gene cag A directly from gastric biopsy specimens appears to be promising and can curtail the lengthy process of culture-based approaches. The procedure proved to be rapid and reliable and could be utilized for diagnostic purposes.

Adult↗