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Biomedical subjects

D Nandi

Publications and source records attributed to D Nandi.

At least 19 recordsLinked to original sources
PubMed2006

Changes in plasma hormones profile and liver function in cows naturally exposed to lead and cadmium around different industrial areas.

The present study was carried out to assess the endocrine status and liver function in adult cows reared in polluted environment around different industrial units in India. The effect on endocrine system was examined by determination of plasma level of thyroid hormones, thyroxin (T4) (n=269) and triidothyronin (T3) (n=269), stress hormone cortisol (n=266), and reproductive hormones such as estradiol (n=84) and progesterone (n=84) in cows (>3 years) reared around different polluted industrial and non-polluted areas. The respective blood lead and cadmium concentration was also determined in all the cows. The mean plasma levels of both T3 and T4 were significantly (P<0.05) higher around lead zinc smelter (2.43+/-0.26 and 41.1+/-2.9nmol/L) and closed lead cum operational zinc smelter (1.81+/-0.16 and 42.4+/-6.2nmol/L), where the mean blood lead level (0.86+/-0.06 and 0.51+/-0.09mug/ml) was also significantly higher than that of cows (0.07+/-0.01mug/ml) from unpolluted areas. Regression analysis of data from 269 cows revealed a significant (P<0.01) positive correlation between the blood lead and plasma T3 (r=0.287) and T4 (r=0.173). The correlation between thyroidal hormones and the blood cadmium concentration (r=-0.079 and -0.48; P>0.05) was not significant. Plasma cortisol level had also a non-significant (P>0.05) correlation (r=-0.092) with blood lead level.However, the mean cortisol level (4.02+/-1.96nmol/L) of cows in phosphate rock mining areas was significantly (P<0.05) higher than that of controls (1.98+/-0.70nmol/L). The mean plasma estradiol level was significantly (P<0.05) higher in cows around closed lead cum operational zinc smelter (47.1+/-19.5pg/ml) than that of the control animals (21.8+/-3.9pg/ml) and in rest of the areas, the difference did not reach the statistical significance (P>0.05). The serum biochemical analysis in 36 cows around lead-zinc smelter with the highest mean blood lead level (0.86+/-0.06mug/ml) amongst all the industrial/urban areas surveyed, and in 15 animals from non-polluted areas revealed a significant positive correlation between blood lead and serum ALT (alanine transaminase) (r=0.688, P<0.01) and AST (aspartate transaminase) (r=0.390, P<0.01) and a negative correlation with serum total lipids (r=-0.337, P<0.05), total protein (r=-0.449, P<0.01) and albumin(r=-0.662, P<0.01). It is concluded from the study that the natural exposure to lead in polluted environments disturbs the endocrine profile and the higher blood lead level alters serum biochemical parameters indicative of liver functions.

Animals↗
PubMed2006

Oxidative stress indices and plasma biochemical parameters during oral exposure to arsenic in rats.

An experiment was conducted to study the response of rat tissues to low level exposure of arsenic (III) for different time periods. Rats were exposed to 0 (Gr. I, healthy control, n=18) or 10 ppm arsenic (Gr. II, positive control, n=18) through drinking water ad lib for a maximum period of 12 weeks. Six rats were sacrificed from each group under light chloroform anesthesia at the end of 4, 8 and 12 weeks of arsenic exposure for collection of blood, liver and kidneys. Samples were processed for estimation of oxidative stress indices and biochemical variables indicative of hepatic and renal functions. Tissue arsenic burden was measured at the end of 12 weeks of exposure. Arsenic treated rats (Gr. II) had comparatively poor body weight gain over time, and the mean body weights of these rats were significantly (P<0.05) lower from 10th weeks onwards. Oral exposure to arsenic for a period of 12 weeks significantly (P<0.05) increased arsenic burden in blood, liver and kidney from arsenic treated rats. This was associated with exposure duration-dependent rise (P<0.05) in lipid peroxidation in these tissues. Superoxide dismutase (SOD) and catalase (CAT) activities increased initially (P<0.05) in all the tissues followed by a declining trend and at the end of 12 weeks, the activities were non-significantly (P>0.05) lower than respective controls. Alterations in most of the biochemical parameters did not reach statistical significance (P>0.05). It was concluded from the present study that low dose arsenic exposure for a shorter period caused activation of intrinsic antioxidant defense whereas a prolonged insult suppressed it. However, biochemical parameters indicative of hepatic and renal dysfunction remained well within the normal range.

Administration, Oral↗
PubMed2006

Tail hair as an indicator of environmental exposure of cows to lead and cadmium in different industrial areas.

This study examines the use of tail hair from cows as a possible biomarker of environmental exposure to lead and cadmium around different industrial areas. Respective blood and tail hair samples were collected from a total of 317 apparently healthy cows above 3 years of age. This includes 287 cows reared in industrial and urban areas and 30 cows from areas free from polluting sources. Significantly (P<0.05) higher lead and cadmium residues were recorded in hair from cows reared around lead-zinc smelter and closed lead cum operational zinc smelter. However, cows from those areas had significantly (P<0.05) higher blood lead but not cadmium concentration as compared to respective control value. Although mean blood lead concentration in cows around aluminum processing plant and urban cum small industrial areas and that of cadmium around steel processing plant were significantly (P<0.05) higher than respective control, the mean hair lead and cadmium content remained statistically (P>0.05) comparable to that of respective control values. The blood lead was significantly correlated with hair lead (r = 0.672, P<0.01) and cadmium (r = 0.309, P<0.05). There was a significant correlation between lead and cadmium concentration (r = 0.610, P<0.01) in hair and a nonsignificant correlation between blood and hair cadmium suggesting that cadmium accumulation in hair was influenced by blood and hair lead concentrations in cows environmentally exposed to lead.

Animals↗
PubMed2005

Effect of cysteine, methionine, ascorbic acid and thiamine on arsenic-induced oxidative stress and biochemical alterations in rats.

Oxidative stress due to enhanced production of free radicals has been incriminated as one of the several mechanisms involved in arsenic-induced toxic effects in different organs. In the present study, ameliorative potential of certain amino acids like cysteine, methionine and vitamins like ascorbic acid and thiamine on some of the parameters indicative of oxidative stress in liver, kidney and blood and of hepatic and renal infliction was investigated in arsenic exposed rats. Rats were given 0 ppm (group I healthy controls) or 10 ppm arsenic in drinking water ad lib for a period of 12 weeks. During oral exposure to arsenic rats of different groups received daily oral dose of placebo, cysteine, methionine, ascorbic acid or thiamine at 25mg/kg body weight. After the end of the experimental period, animals were sacrificed under light anesthesia and blood, liver and kidney were collected. Samples were processed for estimation of arsenic, biochemical parameters indicative of oxidative stress and hepatic and renal function. Arsenic exposure resulted in significantly (P<0.05) higher accumulation of arsenic in blood, liver and kidney. It was associated with significant (P<0.05) rise in lipid peroxide level and decrease in superoxide dismutase and catalase activities in liver and kidneys. However, alterations in biochemical parameters did not reach statistical (P>0.05) significance. Treatment with vitamins and amino acids resulted in reversal of oxidative stress with significant (P<0.05) decline in tissue arsenic burden. All the treatment produced tissue specific changes in lipid peroxide level, antioxidant enzyme activities and tissue arsenic burden.

Alanine Transaminase↗
PubMed2004

Externalising deep brain electrodes: an increased risk of infection?

It is the practice in many centres to externalise deep brain electrodes in functional neurosurgery to confirm efficacy of therapy prior to full implantation of the pacemaker. It has been a concern that such practice might lead to an increased rate of infection. We report a retrospective study of the rates of infection in two major centres where all electrodes are externalised in one centre and directly implanted in the other. We have not found an increased rate of infection as a result of externalisation and feel, particularly in pain patients, that doing so can lead to significant cost savings by avoiding ineffective implantations.

Adult↗
PubMed2004

Increased risk of lead fracture and migration in dystonia compared with other movement disorders following deep brain stimulation.

Deep brain stimulation (DBS) therapy is a continually expanding field in the functional neurosurgical treatment of movement disorders. However, the occurrence of adverse events related to implanted hardware cannot be overlooked. We report on a specific feature noted in our experience of DBS-related complications. From 1998 until present we have found an overall rate of 5.3% of DBS electrode lead dysfunction (out of 133 patients) in our series (slipped leads 2.3%, lead fracture 3.8%). Interestingly, all of these failures occurred in dystonia patients (18.4% of all dystonia patients and 9.2% of all electrodes). We postulate on mechanisms that may explain why these complications predominate in this group of patients.

Adolescent↗
PubMed2003

Post-herpetic trigeminal neuralgia treated with deep brain stimulation.

Post-herpetic neuralgic affects up to 20% of patients after an attack of trigeminal Herpes Zoster infection. Past medical and surgical treatments have been unrewarding. We report the successful treatment of such a case with deep brain stimulation into the region of the contralateral periventricular grey area (PVG) and ventral posterior lateral thalamic nucleus (VPL).

Adult↗
PubMed2003

Post-operative progress of dystonia patients following globus pallidus internus deep brain stimulation.

In the current era of functional surgery for movement disorders, deep brain stimulation (DBS) of the globus pallidus internus (GPi) is emerging as the favoured intervention for patients with dystonia. Here we report our results in 20 patients with medically intractable dystonia treated with GPi stimulation. The series comprised 14 patients with generalized dystonia and six with spasmodic torticollis. Although comparisons were limited by differences in their respective neurological rating scales, chronic DBS clearly benefited both patient groups. Data conveying the rate of change in neurological function following intervention are also presented, demonstrating the gradual but progressive and sustained nature of improvement following stimulation of the GPi in dystonic patients.

Adult↗
PubMed2002

The oscillatory activity in the Parkinsonian subthalamic nucleus investigated using the macro-electrodes for deep brain stimulation.

OBJECTIVES: To investigate the oscillatory activity in the Parkinsonian subthalamic nucleus using the macro-electrodes for deep brain stimulation. METHODS: During bilateral deep brain stimulating electrode implantation, spontaneous and evoked field potentials were recorded from the subthalamic nucleus (STN) in two patients with Parkinson's disease (PD) during spontaneous resting tremor, passive manipulation of the wrist, and following electrical stimulation of the contralateral STN. RESULTS: Frequency analysis of the STN field potentials recorded during spontaneous resting tremor showed significant coherence with electromyographic activity in the contralateral arm, suggesting a close involvement of the STN in the generation of resting tremor in PD. The STN responded to passive movement of the contralateral wrist, but not to ipsilateral movement. High frequency (100 Hz) electrical stimulation of the STN induced tremor (4 Hz) in both forearms, and also oscillation of the contralateral STN (4 Hz). In contrast, low frequency (5 Hz) stimulation induced contralateral arrhythmic involuntary movement (3 Hz), but without altering the contralateral STN activity. CONCLUSIONS: We propose that the functional connection between the STN and arm muscles is mainly contralateral, but cross talk may occur between bilateral STN via a frequency-dependent pathway.

Animals↗
PubMed2002

Electrophysiological confirmation of the zona incerta as a target for surgical treatment of disabling involuntary arm movements in multiple sclerosis: use of local field potentials.

Lesioning or chronic deep brain stimulation (DBS) of the nucleus ventralis intermedius results in abolition of tremor in the contralateral limbs in Parkinson's disease (PD) and also in essential tremor. Recently, chronic DBS of the subthalamic nucleus has also proved to be very effective in reducing contralateral limb tremor in PD. These targets have been less effective in controlling the complex limb tremor often seen in multiple sclerosis (MS). Consequently, other targets have been sought in cases of MS with tremor. We describe a patient with MS with disabling proximal and distal involuntary arm movements in whom we were able to obtain sustained control of contralateral arm tremor and achieve functional improvement of the affected arm by chronic DBS of the region of the zona incerta. We also highlight the important role played by local field potentials recorded from the brain, with simultaneous recording of corresponding EMGs, in target localisation.

Action Potentials↗
PubMed2002

Exploration of the role of the upper brainstem in motor control.

The rostral areas of the brainstem have been extensively studied in higher mammals and to a lesser extent in humans in the last two decades, looking for anatomical, electrophysiological and neurochemical evidence of involvement in the initiation and control of voluntary movement. This has come with the realisation that the axial symptoms of advanced Parkinson's disease (PD), like akinesia, postural impairment and gait freezing, are relatively less responsive to current medical and surgical treatments directed primarily at the basal ganglia and thalamus. The pedunculopontine nucleus (PPN) is one such area of interest. We have found that lesioning and electrical stimulation at high frequencies of the PPN region in the normal behaving primate induces akinesia, and low frequency stimulation can induce tremor. Micro-injections of gamma-aminobutyric acid (GABA) receptor A agonist, muscimol, into the PPN decreases activity. In the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treated Parkinsonian primate model, bicuculline, a GABA(A) antagonist, can alleviate akinesia when infused into the PPN region. This may suggest new targets for treating the intractable akinetic symptoms of advanced PD.

Animals↗
PubMed2001

Motor cortex stimulation for neuropathic pain.

Motor cortex stimulation is increasingly reported in the literature as a surgical option for the alleviation of neuropathic pain. The authors review the published literature and present their results including those demonstrated in a randomized controlled trial that confirmed the efficacy of the procedure. Patient selection and prediction of outcomes, however, remain difficult issues.

Adult↗
PubMed2001

Localisation of the subthalamic nucleus using Radionics Image Fusion and Stereoplan combined with field potential recording. A technical note.

Subthalamic nucleus stimulation is an effective therapy for alleviating parkinsonian tremor, rigidity and bradykinesia. Although microelectrode recording is said to be essential for accurate targeting, this often prolongs the operation and the multiple recording tracts required may increase the incidence of complications, particularly haemorrhage. We describe a technique for implantation of deep brain electrodes in the subthalamic nucleus using MRI/CT fusion for anatomical localisation followed by bipolar recording of focal field potentials via the implanted stimulating electrode for neurophysiological confirmation of the stimulation site. The technique is effective, safe and requires much less time, and can be used as an alternative method to microelectrode recording.

Electric Stimulation Therapy↗
PubMed2001

Lesioning the subthalamic nucleus in the treatment of Parkinson's disease.

Ever since it was demonstrated about twenty years ago by two independent groups (Aziz et al. and Bergman et al.) that the cardinal clinical features of MPTP-induced Parkinson's disease (PD) in non-human primate models can be alleviated by lesions of the subthalamic nucleus (STN), this structure has been the focus of interest for functional neurosurgeons involved in the treatment of PD. Initially lesioning and later chronic high frequency stimulation of the STN has become the standard surgical target of akinetic PD. In this brief report we present our experience with 14 STN lesions (8 unilateral and 3 bilateral) confirmed by post-operative imaging. We found significant improvement in OFF rigidity and in ON tremor following unilateral lesions. The major complications were speech disturbance and L-Dopa resistant limb dystonia. Functional disability scores showed inconsistent reduction. There was insufficient data to comment on the significance of bilateral lesions; however, there was a similar pattern of improvement in tremor and speech disturbance. In addition, there was worsening of gait. We comment on the lower degree of improvement in motor scores in our series compared to the few others in recent literature and stress that even in these studies the UPDRS benefits did not translate directly into functional benefit for the patients.

Electrodes, Implanted↗
PubMed2001

Targeting the subthalamic nucleus.

The small size and surrounding neuronal structures and fibre tracts make the STN a difficult stereotactic target. In this article we present the technique used by us to target the STN. Our combined experience from two centres comprises 18 lesions and 27 stimulator implants in the STN. Our criteria for patient selection and the use of MRI, frame-on CT and volumetric image fusion are presented. The role of a movement disorder specialist neurologist in the operating theatre, local field potential recording, impedance monitoring, macrostimulation, post-operative CT/MRI and test stimulation are detailed.

Electric Stimulation Therapy↗
PubMed2000

The multiple active enzyme species of gamma-aminobutyric acid aminotransferase are not isozymes.

Purified gamma-aminobutyric acid aminotransferase (GABA-AT) from pig brain under certain conditions gave a single band on 12% NaDodSO(4)-PAGE, whereas two or three distinct bands were observed on 7.5% native PAGE. These multiple active species were isolated by 5% preparative gel electrophoresis and characterized by N-terminal sequencing and MALDI-TOF mass spectrometry. The results indicate that these active enzyme species are not GABA-AT isozymes in pig brain, but are the products of proteolysis of the N-terminus of GABA-AT, differing by 3, 7, and 12 residues from the full sequence (as deduced from the cDNA), respectively. Conditions for obtaining the nontruncated GABA-AT were found, and the potential cause for the proteolysis was determined. It was found that Na(2)EDTA inhibits the N-terminal cleavage during GABA-AT preparation from pig brain. The presence of Triton X-100 in the homogenization step is partially responsible for this proteolysis, and Mn(2+) strongly enhances the protease activity, suggesting the presence of a membrane-bound matrix metalloprotease that causes the N-terminal cleavage.

4-Aminobutyrate Transaminase↗