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Biomedical subjects

D Verma

Publications and source records attributed to D Verma.

At least 19 recordsLinked to original sources
PubMed2006

Structural and functional analysis of a salt stress inducible gene encoding voltage dependent anion channel (VDAC) from pearl millet (Pennisetum glaucum).

We have cloned and characterized a gene encoding voltage-dependent anion channel from Pennisetum glaucum (PgVDAC). PgVDAC was identified while isolating genes that were differentially up-regulated following salt stress. The genomic organization of PgVDAC clone was well conserved compared to other plant VDAC genes in terms of number of introns, their position and phasing, however, the primary amino acid sequence of voltage dependent anion channel (VDAC) proteins did not show much conservation with other plant VDACs but their secondary and tertiary structures are well conserved as predicted by in silico structural and CD spectra analyses and results show it to be a typical membrane-spanning beta-barrel leading to the formation of pore in the membrane. The heterologous expression of PgVDAC protein in yeast strain lacking the endogenous mitochondrial VDAC gene could not functionally complement it as was also previously observed for the potato VDAC. Using real-time quantitative PCR analysis it was found that transcript expression profile of PgVDAC was quantitatively and kinetically up-regulated in response to salinity, desiccation, cold and exogenous application of salicylic acid (SA); however, there was no effect of exogenous application of abscisic acid (ABA) on its expression. Constitutive over-expression of PgVDAC appears to be deleterious in transgenic rice plant; however, low level of up-regulation imparted salinity stress adaptive response. A search for a more suitable inducible transgene system is currently under way to understand PgVDAC expression levels in plant development and its role in stress adaptation.

Amino Acid Sequence↗
PubMed2003

Virtual reality simulator for vitreoretinal surgery.

AIM: To develop computer simulation of steps in vitreoretinal surgery using virtual reality technology. MATERIAL AND METHODS: A workstation with three-dimensional position tracking stylus was attached to a Pentium II desktop PC with a graphic accelerator. Computer algorithms were developed using Open GL and Microsoft Visual C++ languages to control the interaction and update the visual feedback tracking the instruments. Soft tissue computer modelling was carried out to mimic the removal of a vitreous opacity. Lens touch with the instruments was also detected. Mathematical modelling to allow for lens distortion was taken into account. RESULTS: A virtual reality computer model has been developed that can simulate initial steps of vitreoretinal surgery. Soft tissue modelling of the vitreous opacity and its removal by the vitrector was successfully simulated. The movements of the active and passive instruments in the dummy eye corresponded to the movements on the computer screen. On evaluation of the system, there was a minimal but discernable time lag between the stylus movement and the visual feedback. There was no tactile feedback when the lens touch was simulated. No further complex vitreoretinal surgery simulation was possible at this stage.

Algorithms↗
PubMed2002

Evaluation of posturing in macular hole surgery.

AIM: To objectively evaluate the postoperative face down posturing in macular hole surgery. MATERIALS AND METHODS: An electronic device called 'Maculog' was developed consisting of three basic components, a mercury switch triggered by the angle of tilt placed inside an earpiece, a data-recording device connected to the earpiece with cables and a windows based software program, specially written to analyse the recorded data in the form of tables and graphs. Ten patients undergoing macular hole surgery were fitted with the device on the first postoperative day before discharge. They were also asked for a subjective record of their posturing times. Four patients were given a posturing chair to take home. The device was retrieved after the first week and the data were downloaded to a PC for analysis. The actual posturing times recorded on the device were compared to the patients' own recollections. Results In all ten patients the actual posturing time was less than the time they had recorded themselves. The average actual posturing time was 48% of the perceived posturing time. The worst time for posturing, as expected, was between midnight and early morning. The compliance was better in patients who used the posturing chair. CONCLUSIONS: It is feasible to quantify the time of posturing using an electronic device and computer analysis. The study has shown that the actual posturing time is significantly less than the perceived posturing time. A further large study using 'Maculog' is now planned to correlate actual posturing time to the results of macular hole surgery.

Aged↗
PubMed2001

Telemedicine in ophthalmology.

Comprehensive telemedicine promises a world of medicine freed of geographic borders, time zones, and personnel shortages. It could open the door to more accessible medical delivery systems and economical widespread screening for disease. No region of the world would be too remote or too poor to receive high quality medical care. This article traces the development and current applications and initiatives in the field of telemedicine as applied to ophthalmology in the wider sense. Uses for clinical diagnosis and management, screening, research, education and peer interaction are discussed.

Confidentiality↗
PubMed2001

Prognostic significance of apoptosis in squamous cell carcinoma of oral cavity with special reference to TNM stage, histological grade and survival.

Apoptotic count was assessed in 38 cases of squamous cell carcinoma of oral cavity by light microscopy and correlated with TNM stage, histological grade and survival. A direct correlation with the TNM stage (p = 0.0166) and an inverse correlation with the histological grade (p = 0.03) was found, however no correlation was found with the survival. Apoptotic count was significantly different between well and moderately differentiated carcinoma (p = 0.347) and well and poorly differentiated carcinoma (p = 0.0190). Thus apoptotic count may have prognostic value particularly in combination with staging and histological grade.

Adult↗
PubMed2000

Stress induced phosphate solubilization in bacteria isolated from alkaline soils.

Phosphate solubilizing bacteria NBRI0603, NBRI2601, NBRI3246 and NBRI4003 were isolated from the rhizosphere of chickpea and alkaline soils. All four strains demonstrated diverse levels of phosphate solubilization activity under in vitro conditions in the presence of various carbon and nitrogen sources. Acid production may have contributed to phosphate solubilization, but was not the only reason for phosphate release into the medium. Among the four strains, NBRI2601 was the most efficient strain in terms of its capability to solubilize phosphorus in the presence of 10% salt, pH 12, or 45 degrees C. The strains showed varied levels of phosphate solubilization when the effects of different sources of nitrogen were examined during growth. The presence of low levels of Ca(2+) and EDTA in the medium enhanced phosphate solubilization.

Bacteria↗
PubMed2000

[Testing a computer-assisted bending machine for manufacturing orthodontic treatment elements].

The use of suitable orthodontic devices producing desired defined force systems is of importance for successful orthodontic treatment. Bending loops can be difficult and time-consuming. Computerised fabrication would enable very precise reproduction of individual loops. A bending machine has now been developed within the framework of a computer-assisted treatment concept. In this study, a prototype machine was used to fabricate U-, T- and delta loops made of stainless steel, cobalt chromium and titanium molybdenum wire. The various geometric parameters of each loop were measured to determine how precisely they had been produced. Furthermore, the force system of each loop were experimentally investigated during simulated activation in an orthodontic measurement and simulation system. The results indicate that the geometric parameters had an average error of 2.8 degrees for angles and 0.9 mm for lengths. Owing to the fabrication errors, loops of the same type produced different force systems. Overall, the new bending machine can fabricate different types of loop, but the requirements of very precise fabrication are currently not met. This fact, together with further limitations in terms of configuration, means that the machine cannot be used routinely at present. However, the machine can nevertheless be considered a good basis for further development.

Computer-Aided Design↗
PubMed1999

Recurrent amaurosis fugax without haemodynamically significant ipsilateral carotid stenosis.

PURPOSE: This study was performed to investigate the causes of recurrent amaurosis fugax in patients without haemodynamically significant carotid stenosis. METHODS: Pulsatile ocular blood flow (POBF), ocular pulse amplitude (PA) and ocular perfusion pressure (OPP) were recorded for 15 patients and 15 age-matched controls. RESULTS: No significant difference in OPP or POBF was found between the two groups. However, the PA was significantly greater in the control group (p=0.01). CONCLUSION: The results of this study suggest that for some patients with recurrent amaurosis fugax, their symptoms may occur secondary to ocular small vessel disease.

Aged↗
PubMed1999

Management of ocular perforations resulting from peribulbar anaesthesia.

PURPOSE: To analyze the clinical presentation and outcome of treatment for globe perforation secondary to peri-bulbar anaesthesia. METHODS: Eight patients (3 females and 5 males) aged 66-84 years were included in the study. Ocular perforations were suspected in 3 cases before or during surgery, in 4 cases diagnosis was established within one week and in one case at 3 weeks. Three patients underwent indirect argon laser photocoagulation to seal the retinal break, one patient had cryotherapy, 3 patients underwent a pars plana vitrectomy with fluid gas exchange and endo-laser; and one patient refused any further treatment. RESULTS: The final visual acuity after a mean follow up of 14 months was better than 6/9 in 2 patients, between 6/9-6/12 in 4 patients, and perception of light in 2 patients. CONCLUSION: If diagnosed early and treated adequately, a majority of patients with globe perforation during periocular anaesthetic could be saved.

Aged↗
PubMed1999

The 5HT3 receptors and the descending nociceptive pathway--a review.

There has been a huge and exciting increase in our recent understanding of the pathogenesis of pain. Neurophysiological and pharmacological evidence have demonstrated that 5-HT now plays an important albeit discrete role in pain transmission at various levels of the pain pathway. Although 5-HT is clearly involved in spinal analgesia, its mode of action is still obscure and perplexing perhaps because it has multiple and often opposing effects mediated by its multiple receptor subtypes. The involvement of 5-HT3 antagonists and agonists have been found to either facilitate or inhibit nociceptive processing in the dorsal horn cells. Thus the understanding of the descending serotonergic analgesic system may enable the development of new non-opioid, non-addictive analgesics.

Humans↗
PubMed1998

Survey of diabetic retinopathy screening services in England and Wales.

A postal survey of diabetologists was conducted regarding the provision of diabetic retinopathy screening services in England and Wales. About 2.5 million people had no existing or planned screening service. For the rest, the perceived percentage of patients with diabetes screened varied from less than 25% to more than 90%. Multiple modes of screening were used in most units. Lack of funding was identified as the major reason for non-provision of an adequate screening service. About 18% of the units had to use research or charitable funds for screening. Only 50% of the units using optometrists for screening had standard protocols for referral. The average wait before an ophthalmologist's opinion on sight threatening retinopathy detected by screening was unacceptably high in some units. We would suggest that establishment of identical screening protocols and provision of adequate funding on a national basis ought to be the priority if incidence of blindness from diabetic retinopathy is to be reduced according to the St Vincent Declaration.

Diabetic Retinopathy↗
PubMed1998

Ischemic retinitis as a result of acute episodic blood loss.

Acute episodic blood loss leads to a sudden change in the haemodynamics leading to a number of ocular and systemic effects. Occurrence of ischemic retinitis secondary to acute blood loss is of a very rare occurrence. This communication presents a case of infarction of the nerve fibre layer secondary to acute blood loss in a 55-year-old male.

Acute Disease↗
PubMed1996

Workplace organizational correlates of lost-time accident rates in manufacturing.

We report the results of a questionnaire survey of manufacturing workplaces related to the lost-time frequency rates (LTFR) for Workers' Compensation claims. Six types of industry were chosen.' metal articles, plastic articles, grain products, textile manufacturing, printing, and automobile manufacturing. LTFR were standardized by type of industry. Stratifying simultaneously by number of employees and LTFR category, we sampled 718 workplaces. A mail questionnaire to labor and management representatives provided at least some information on 58%. Response rates were similar across LTFR categories, and telephone interviews of non-responders showed little difference in their replies from those obtained in completed questionnaires. A large number of variables were examined. Apart from statistical significance, we looked for consistency in trends across LTFR categories and in patterns for similar questions. Significant associations grouped into several areas. Lower LTFR were associated with: concrete demonstration by management of its concern for the workforce; greater involvement of workers in general decision-making; greater willingness of the Joint Health and Safety Committee to solve problems internally; and greater experience of the workforce. Variables that were not significant included profitability and financial performance. A final stepwise multiple regression explained 19% of the variance in LTFR, although this analysis suffered from several limitations.

Absenteeism↗