Showing papers by "Rajesh Kumar published in 1999"

A Steady-Hand Robotic System for Microsurgical Augmentation

Abstract: This paper reports the development of a robotic system designed to extend a human’s ability to perform small-scale (sub-millimeter) manipulation tasks requiring human judgment, sensory integration,...

A Steady-Hand Robotic System for Microsurgical Augmentation

Abstract: This paper reports the development of a robotic system designed to extend a human’s ability to perform small-scale (sub-millimeter) manipulation tasks requiring human judgement, sensory integration and hand-eye coordination. Our novel approach, which we call “steady hand” micromanipulation, is for tools to be held simultaneously both by the operator’s hand and a specially designed actively controlled robot arm. The robot’s controller senses forces exerted by the operator on the tool and by the tool on the environment, and uses this information in various control modes to provide smooth, tremor-free precise positional control and force scaling. Our goal is to develop a manipulation system with the precision and sensitivity of a machine, but with the manipulative transparency and immediacy of handheld tools for tasks characterized by compliant or semi-rigid contacts with the environment.

Prevalence and determinants of hypertension in an un-industrialised rural population of North India.

Abstract: Recent studies have indicated a rising prevalence of hypertension in rural and urban areas of India. A population-based survey was carried out during 1994-1995 in seven rural and non-industrialised villages around RaipurRani block in the state of Haryana, India, to determine the prevalence of hypertension and its associated risk factors. A total of 2559 individuals (86% of the eligible population) in the 16 to 70-year age group were interviewed using a pre-tested structured questionnaire to find out the lifestyle characteristics. Three blood pressure (BP) readings were recorded with a random zero sphygmomanometer at three different times. One hundred and fourteen individuals (4.5%) were found to be hypertensive according to JNC V criteria (BP of > or = 140/90 mm Hg). Mean systolic and diastolic BPs were 116.9 and 71.7 mmHg in males and 119.1 and 72.7 mm Hg in female subjects respectively (P 0.05). In addition hypertensives had higher mean weight (53.8 kg vs 48.4 kg, P < 0.001) and higher body mass index (21.5 vs 18.9 kg/m2, P < 0.001). Analysis showed that advancing age, sedentary lifestyle, higher alcohol consumption and higher body mass index are the risk factors for hypertension in the rural un-industrialised population of India.

Loss of heterozygosity at chromosome 9p21 (INK4-p14ARF locus): homozygous deletions and mutations in the p16 and p14ARF genes in sporadic primary melanomas.

Abstract: Loss of heterozygosity (LOH) was determined in 45 sporadic primary melanomas at six polymorphic microsatellite markers that flank the INK4a (p16-p14ARF) locus on chromosome 9p21. We also determined allelic loss at two markers on chromosome 9q and two markers at the Rb locus on chromosome 13. Homozygous deletion of the p16 and p14ARF genes was determined by a fluorescent-based quantitative multiplex polymerase chain reaction method. LOH at one or more polymorphic microsatellite markers on locus 9p21 was found in 32 of the melanomas (71%). The highest proportion of LOH was found at markers D9S736 and D9S104, which are telomeric and centromeric to the INK4 locus, respectively. Five melanomas showed LOH at all the analysed markers located on chromosome 9p21. LOH at markers D9S942 and D9S974, which are located close to the p16 and p14ARF genes, was found in 39% and 46% of melanomas, respectively. Analysis of the marker D9S257 on 9q22.1 showed LOH in 13 melanomas (44% of the informative cases). A subset of melanomas with LOH at the INK4 locus also carried inactivating mutations within the p16 coding sequence. Four melanomas carried homozygous deletions at the p16-p14ARF locus. Our results suggest, besides the involvement of the INK4 locus in sporadic melanomas, the possibility of the existence of additional tumour suppressor loci on chromosome 9.

Fate of bacterial pathogens in cattle dung slurry subjected to anaerobic digestion

Abstract: The survival of certain pathogenic bacteria was studied in anaerobic batch digesters at room temperature (18–25 °C) as well as at 35 °C under laboratory conditions. The survival of Escherichia coli and Salmonella typhi at room temperature was upto 20 days whereas at 35 °C it was only upto 10 days. Shigella dysenteriae was found to be the most sensitive organism which could survive upto 10 days at room temperature and upto 5 days at 35 °C. The longest survival was observed in case of Streptococcus faecalis which could survive upto 35 days at room temperature and 15 days at 35 °C. The survival time of Salmonella typhi increased when the solid contents of the digester were elevated from 9% to 15%.

Experiments with a steady hand robot in constrained compliant motion and path following

Abstract: We consider the problem of cooperative manipulation to improve positioning and path following abilities of humans. Using a specially designed actuated manipulator and "steady hand" manipulation we report on compliant path following strategies and their experimental evaluation. Detecting lines and simple curves by processing images from an endoscope mounted on the robot, we traverse these curves autonomously, under direct user control, and in an augmented mode of user control. Anisotropic gains based on gradient information from the imaging reduce errors in path traversal.

Performance of Robotic Augmentation in Microsurgery-Scale Motions

Abstract: This paper is part of the development process of a microsurgical “cooperating” assistant. To evaluate its applicability to augment fine surgical motions, we test precision and operator perception in simple microsurgical scale pick and place motions. Such motions are common in microsurgical procedures (e.g. micro-vascular anastomosis). The experiments test the users’ ability to position a common surgical tool to 250, 200 and 150 micrometer accuracy. These experiments were performed using two test platforms. The new “steady hand” robot designed for microsurgery and the LARS robot (a laparoscopic camera holding robot) adapted for this purpose. Comparative results for several parameters including time, success rate, error rate, number of attempts are included. Comparison of performance of the two robots for these tasks is also included. The results support our claim that the new “steady hand” robot augments human performance for microsurgery-scale motion.

A Testbed System for Robotically Assisted Percutaneous Pattern Therapy

Abstract: This paper presents a second generation prototype image-guided robotic system for percutaneous delivery of surgical devices and therapeutic agents, with potential applications in the treatment of liver cancer and other malignancies. The system is intended to deliver these devices and therapies more consistently and accurately than a physician can achieve freehand. This capability will permit the treatment of smaller lesions, will enable the physician to better achieve optimized patterns of therapy distribution, and will allow for more rapid re-targeting for multiple lesions. The system will allow treatment of patients for whom surgery is contraindicated and could potentially replace major surgery, reducing patient morbidity and mortality, as well as the cost of treatment. The new prototype system uses new, modular hardware and software components, which improve its accuracy, usability, and flexibility as compared to the first generation prototype. Techniques for image processing, both in 2D and 3D images, planning, and fiducial registration have also been developed. In vitro, the system achieves submillimetric accuracy in the placement of simulated treatment devices from a preoperative plan generated from 3D imagery. Some initial in vivo considerations have also been addressed, and work is ongoing in this area.

Expression of 25(OH)D3 24-hydroxylase in distal nephron: coordinate regulation by 1,25(OH)2D3 and cAMP or PTH.

Abstract: Previous studies using microdissected nephron segments reported that the exclusive site of renal 25-hydroxyvitamin D3-24-hydroxylase (24OHase) activity is the renal proximal convoluted tubule (PCT)...

Standardization of method for lactoperoxidase assay in milk

Abstract: The spectrophotometric method used to measure lactoperoxidase activity in milk was standardized. The assay system consisting of ABTS (2,2' -azinobis-(3-ethyl benzthiazoline-6-sul- phonie acid)) as chromogenie substrate gave a Iinear initial rate of reaction up to 700 ug-L:' lac- toperoxidase concentration, with maximum activity at pH 6.0. The lactoperoxidase activity was higher in buffalo milk than cow milk and the corresponding concentration of the enzyme was 31 and 24 mg-L", respectively. A loss of 10-15 % of peroxidase activity occurred on the preparation of rennet whey or acid whey. © InralElsevier, Paris lactoperoxidase assay 1cow milk 1buffalo milk 1rennet whey 1acid whey

A Progressive Cut Refinement Scheme for Revision Total Hip Replacement Surgery Using C-arm Fluoroscopy

Abstract: We describe a new method to cut a precise, high quality cavity in Revision Total Hip Replacement surgery (RTHR) using a set of intra-operative C-arm fluoroscopic images. With respect to previous approaches, our method provides the following new features: (1) a novel checkerboard plate was designed to correct the geometric distortion within fluoroscopic images. Unlike previous distortion correction devices, the plate doesn’t completely obscure any part of the image, and the distortion correction algorithm works well even when there are some overlaid objects in field of view; (2) a novel corkscrew fiducial object attached to the robot end-effector was designed, and a 6D pose estimation algorithm based on the 2D projection of the corkscrew is developed and used in robot-imager registration and imager co-registration; (3) we propose a progressive cut refinement scheme and an iterative cut location algorithm which utilizes image subtraction and 2D anatomy contour matching techniques. Several cutting experiments and some simulated experiments have been conducted to assess our techniques. The results indicate that our scheme is a promising method for RTHR application.

Kala-azar epidemic in Varanasi district, India.

Abstract: The epidemiological characteristics of the kala-azar outbreak in Pandit Ka Purva India were investigated using standard techniques. A door-to-door survey of 518 persons in Pandit Ka Purva was carried out in November and December 1995 using a predesigned and pretested proforma. Independent variables such as age sex and literacy were considered in the survey. Results showed that the overall prevalence and case fatality of the disease were 12.9% and 10.5% respectively with a history of fever and hepatosplenomegaly noted for all cases. Culture and Giemsa staining confirmed indications of parasites in the bone marrow or splenic aspirate smears. The disease was more prevalent among adults but it occurred also among children. However there was no clear linear relationship between the prevalence of the disease and age group. Kala-azar was more prevalent among males and its occurrence did not correlate significantly with income. In view of the outbreak of kala-azar in Pandit Ka Purva it is essential for health authorities to take immediate measures to control the epidemic and prevent its spread to neighboring villages. This will necessitate the development of shorter treatment courses the improvement of diagnostic methods and close cooperation between universities public health agencies and the government.

Community based study of reproductive tract infections among ever married women of reproductive age in a rural area of Haryana, India.

Abstract: A community based study was carried out to estimate the load of reproductive tract infections (RTIs) among ever married rural women aged 15-44 years and utilisation of a mobile village based treatment facility by them, during 1997. Complete household survey was done in 10 randomly selected villages of Mahindergarh district in Haryana, India. A total of 2325 women were interviewed by auxiliary nurse midwives and were invited for medical examination in a health camp set-up in their village. Sixty-one percent (1415/2325) women reported symptoms of RTIs. Only 35% (812/2325) had their per-speculum examination done. Out of those examined, 32% (263/812) had vaginitis, 21% (175/812) had cervicits, and 19% (156/812) had pelvic inflammatory disease. Vaginal smear of those having discharge revealed that 48% (231/476) had bacterial vaginosis, 0.8% (4/476) had fungal infection 9% (44/496) had trichomonal infection and none was found to be having gonococcal infection. Tests for chlamydial infection could not be performed as the cost was not affordable. Eighty-nine percent of women who reported symptoms of RTIs had not consulted anyone for their problem prior to our village based camp. Only 42% symptomatic and 24% asymptomatics availed the services even in the village based camps. Study revealed high load of reproductive tract infections and low utilisation of treatment facility. In-depth studies are required to understand for high RTI morbidity load and low treatment seeking rate so as to design an appropriate RTI control programme.

The Asian crisis : an alternate view

Abstract: The paper argues that the macro focus of the literature on the Asian crises is not helpful in understanding the causes of the crises. The actual causes lie deeper in the operation of the real, that is, the corporate sector. In this context, the paper analyzes the micro behavior of individual firms.

Optimum duration of splinting after endopyelotomy.

Abstract: Objective: Endopyelotomy is a well-accepted modality of treatment for pelviureteral junction (PUJ) obstruction, but the time period of stenting is debatable. The present study was aimed at evaluating the optimum duration and effectiveness of splinting after endopyelotomy. Patients and Methods: Twenty-nine consecutive patients with primary PUJ obstruction were randomized to have an external splint (for economic reasons) for 2 weeks or 4 weeks. Thirteen patients in each group were available for evaluation. The groups were comparable in age, sex, symptoms, and preoperative glomerular filtration rate (GFR). All patients underwent antegrade endopyelotomy with placement of an 8F–12F polyethylene splint across the PUJ. A nephrostogram was performed after removal of splint at 2 or 4 weeks. Nondraining units were managed by putting in a 6F double-J stent for 6 weeks and considered failures. Patients were evaluated at 3, 6, and 12 months for symptomatic improvement, change in GFR, and drainage pattern on a...

Spontaneous perforation of the common bile duct in infancy: role of Tc-99m mebrofenin hepatobiliary imaging.

Abstract: A 2-month-old infant had jaundice that began 3 days after birth. The clinical features were suggestive of biliary obstruction. Tc-99m mebrofenin hepatobiliary imaging confirmed the diagnosis of spontaneous perforation of the common bile duct, and surgical intervention resulted in progressive recovery.

Breast self examination for early detection of breast cancer.

Abstract: Breast cancer is the commonest form of cancer in women in Western countries and second most common in women of developing countries like India. In the absence of an exact aetiological agent for breast cancer, the most appropriate way of controlling it is by early detection and treatment. Of the various methods of screening for breast cancer, mammography is the method of choice but its use is limited due to high cost and unavailability. Considering this, breast self examination (BSE) is an ideal method which can be done by every woman at her leisure time with little training. Medical and paramedical professionals can act as trend setters in promoting BSE for control of breast cancer in the community.

Dynamics of contraceptive use in a rural community of Haryana.

Abstract: A cross-sectional survey was carried out to study the dynamics of contraceptive use in three villages of Raipur Rani block in district Panchkula, Haryana. A female social worker interviewed 600 ever-married women aged 15-44 years using a semi-structured interview schedule. More than 75% of the respondents were aware about modern contraceptives. Fifty-nine percent of the couples had used contraceptives. Among the 351 ever-users, the first contraceptive method used was sterilization in 41.3%, condom in 35.6%, IUD in 17.9%, and oral pills in 5.1%. Subsequently, many of them either discontinued or shifted to other methods. At the time of survey, 236 (39.3%) were using a contraceptive. Most of the current users (225) had opted for tubectomy, and only a few (4) had accepted vasectomy. Supplies of contraceptives were obtained mainly from government hospitals and sub-health centres. Common reasons for discontinuation were perceived untoward effects (37.1%), desire for more children (32.6%), and failure of the contraceptive method (19.0%). Most of the respondents obtained contraceptives from Government health posts. Counselling and follow-up services should should be strengthened so that contraceptives are used regularly and effectively for longer periods.

Health awareness and treatment compliance of high blood pressure among women in a peri-urban colony of Chandigarh, India.

Abstract: Health awareness is a central issue in the control of hypertension. In a cross-sectional survey among 1727 women of > 30 years, 2 blood pressure recordings were done in 1686 cases. The prevalence of hypertension was found to be 13.1% (221 out of 1686 cases). A random sub sample of 72 hypertensive women above 30 years of age from a peri-urban colony of Chandigarh was selected to find out health awareness and treatment compliance of hypertension. Sixty-three (87.5%) of the selected women were aware of their high blood pressure. However, only 12 women (16.7%) who were on treatment had achieved control of blood pressure (< 140/90 mm Hg). Main reasons for discontinuing the treatment were ignorance about the need of regular treatment (33.3%), high cost of medicines (19.44%) and non-availability of a family member who can go with the patient to hospital (9.72%). Twenty-six (36.1%) hypertensive women did not know the importance of weight reduction for controlling high blood pressure. Twenty-three (31.9%) hypertensive women were currently smoking. A comprehensive health education approach involving health care professionals, patients and general population should be launched to improve the care of hypertensives in the community.

Comparison of 32p-postlabeling and high-resolution gc/ms in quantifying n7-(2-hydroxyethyl)guanine adducts

Abstract: This study compares (32)P-postlabeling and high-resolution gas chromatography/mass spectrometry (GC/MS) in the quantification of N7-(2-hydroxyethyl)guanine adducts (7-HEG) in DNA obtained from the same tissue samples of control rats and rats exposed to ethene. The samples were obtained from two independent studies. In one study, male Sprague-Dawley rats were exposed to 300 ppm ethene for 12 h/day for 3 days ("Euro samples"). In the other study, male F-344 rats were exposed to 3000 ppm ethene for 6 h/day for 5 days ("U.S. samples"). DNA from liver and kidney from the European study was isolated in the European laboratory, and DNA from liver and spleen from the U.S. study was isolated in the U.S. laboratory. The DNA samples were coded, divided into two portions, and exchanged between the two laboratories. All DNA samples from both laboratories were analyzed with respect to 7-HEG adducts by (32)P-postlabeling and high-resolution GC/MS in the European and U.S. laboratories, respectively. However, the U.S. samples were repurified in the European laboratory before the postlabeling analysis. The data from the Euro and the U.S. samples were therefore treated separately in the regression analysis of the (32)P-postlabeling versus GC/MS data. The slope of the regression line for the Euro samples was 1.19 (r = 0.97), implying that the GC/MS data were slightly lower than the postlabeling data (one possible outlier was excluded). The slope of the regression line for the U.S. samples was 0.61 (r = 0.94), implying that the GC/MS data were somewhat higher than the postlabeling data. The main conclusion from this study is that there is very good agreement between the (32)P-postlabeling and high-resolution GC/MS methods in quantifying 7-HEG adducts to DNA, particularly when identical DNA samples are analyzed and the RNA content is <2%. The paper also discusses the background levels of adducts, the interorgan distribution, comparison between different strains, and exposure conditions.

Investigation of an epidemic of Reye's syndrome in northern region of India.

Abstract: Objective To determine the extent, epidemiological and clinical features of an epidemic of non-inflammatory encephalopathy in northern region of India. Design Surveillance of referred cases having unconsciousness after a short bout of fever during October and November 1997. Case control study in 7 most affected villages. Methods Active case finding was done to assess the extent and severity of the epidemic by interviewing health professionals and by reviewing mortality records in 10 districts of Haryana, Punjab and Chandigarh. A house to house survey was conducted in seven most affected villages. A case was defined as any child of less than 15 years of age, who had prodromal fever followed by vomiting and unconsciousness with subsequent recovery or death. Two age and sex matched controls who had fever without unconsciousness were taken for each case, one from nearby house and another staying furthest from the affected house. These groups were compared for various epidemiologic factors, clinical features and treatment pattern. Residual medicines used by affected patients were tested for presence of salicylate. Local village practitioners were interviewed for their knowledge and attitude towards use of aspirin in a febrile child. Results Information regarding 129 affected children (M: F=1 : 1) could be obtained. Age ranged between 1 to 12 years (mean 5.8 years). Most were from rural or semi-suburban areas. Attack rate was 5.4/1000 and case fatality rate was 72%. Multiple sibs were affected in 9.3%. History of fever was reported by 83%, vomiting preceding unconsciousness by 83% and abnormal behavior by 65%. Abnormal posturing was reported in 55%. Seventeen (61%) of 28 samples had IgM antibodies in serum/CSF against measles. Twelve (36%) of 33 serum samples tested positive for Varicella zoster virus. None gave history of aspirin intake and 10 samples of residual drugs did not contain salicylate. However, 6 out of 19 blood samples taken from affected patients contained salicylate. Environmental factors were in favor of Japanese encephalitis (JE) but brain biopsy and serology disproved it. Based on earlier report of JE from this area, the cases in present epidemic were being reported as JE before this study was undertaken. Intensive fogging with malathion was being undertaken as antimosquito measure, specially around the affected houses. Local village practitioners (n = 37) were unaware of contraindications of aspirin in a febrile child. Conclusion Measles and varicella zoster emerged as the probable etiologies for the viral prodrome precipitating these cases of Reye's syndrome. Aspirin might have a contributory role. Malathion is another putative cofactor.

Radial displacements of an infinite liquid saturated porous medium with cylindrical cavity

Abstract: The components of radial displacements in solid and liquid parts of a liquidsaturated porous medium with spherical cavity subjected to an arbitrary time dependent force have been obtained. Laplace transform technique has been used to solve the problem. Numerical calculation has been performed for two specific models. Variations of displacement in solid and liquid parts of the medium have been shown graphically.

Unilateral hydrocephalus in paediatric patients, a trial of endoscopic fenestration.

Abstract: Two uncommon cases of unilateral, asymmetrical hydrocephalus secondary to membranous occlusion of foramen of monro are described. Both the cases presented with clinical features of raised intracranial pressure and their cranial computerized scans (CT) revealed asymmetrical dilatation of lateral ventricles with displacement of septum pellucidum towards the side of smaller ventricle. Neuroendoscopic fenestration of septum pellucidum and foramen of monro was tried in both the cases, which remained successful in first, while the second case required unilateral ventriculoperitoneal shunt, due to failed endoscopic negotiation of narrowed foramen of monro and intraoperative bleeding during endoscopic intervention.

Exciton-phonon scattering in GaAs/AlAs quantum wires

Abstract: We perform temperature-dependent photoluminescence measurements on a GaAs/AlAs quantum wire array (QWR-A) with a very low disorder. Using these, we deduce the temperature dependence of the homogeneous linewidth of the quasi-one-dimensional exciton to show that exciton scattering rates with optical phonons are enhanced in the QWR-A in comparison with a reference quantum well.

Primary malignant rhabdoid tumours of brain, clinicoradiological findings of two cases.

Abstract: Malignant rhabdoid tumours (MRT) are extremely malignant, highly aggressive and uncommon renal neoplasms of childhood with very poor prognosis. About fifteen cases of primary intracranial MRT (with their clinical details) are reported in English literature, following the recognition of this entity in 1978. Two cases of MRT are reported here. The first case, one year male baby was admitted with a very large, infiltrative, posterior fossa mass. He required elective ventilation, following the tumour decompression but ultimately died of respiratory failure during the process of weaning from the ventilator. The second child was operated for an extremely vascular, very friable, solid and lobulated tumour of temporal lobe. Radical microsurgical decompression of mass was achieved, however the child developed massive recurrence, documented five weeks after the surgery while on radiotherapy. His recurrence showed partial response to radiotherapy and chemotherapy. The child is alive at 8 month's follow up, but probably passing the terminal days of his life. Hence the recognition of this entity is very essential for the aggressive management and prognostication of the patient, which obviously seems to be different from primitive neuroectodermal tumour.

Malignant pleural mesothelioma without asbestos exposure.

Abstract: A 45-year-old male, non smoker and lecturer by profession was diagnosed as an advanced case of bilateral mesothelioma involving lung and pleura. He was never exposed to asbestos, which makes it a rare case.

Identification of copper-zinc superoxide dismutase gene from enteroaggregative Escherichia coli.

Abstract: We describe here the identification of sodC gene from enteroaggregative Escherichia coli (EAggEC). A 294 bp gene-specific fragment was amplified from the organism by DNA as well as RT-PCR using primers from bacterial sodC sequences. The metal co-factor present in the protein was confirmed by running samples in native gels and inhibiting with 2 mM potassium cyanide. However, the nonpathogenic E. coli possesses the gene but does not express it. Thus, the presence of copper-zinc superoxide dismutase encoded by sodC was demonstrated for the first time in EAggEC, which means it could be a novel candidate for a virulence marker.