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Biomedical subjects

D Talwar

Publications and source records attributed to D Talwar.

At least 19 recordsLinked to original sources
PubMed2003

Lower concentrations of carotenoids in the critically ill patient are related to a systemic inflammatory response and increased lipid peroxidation.

BACKGROUND: Critically-ill patients have low circulating concentrations of vitamin antioxidants. The functional significance of such reductions is not clear. AIMS: To determine whether the presence of a systemic inflammatory response was associated with reduced circulating alpha-tocopherol and carotenoid concentrations and an increase in lipid peroxidation as evidenced by malondialdehyde. METHODS: Healthy controls (n=24) and critically-ill patients (n=43) had circulating concentrations of C-reactive protein, cholesterol, triglycerides, malondialdehyde, alpha-tocopherol, lutein, lycopene, alpha- and beta-carotene measured during ITU stay. RESULTS: In the critically-ill group circulating concentrations of C-reactive protein and malondialdehyde were significantly higher (P<0.05) and cholesterol, triglyceride, alpha-tocopherol, lutein, lycopene, alpha- and beta-carotene were all significantly lower (P<0.01) compared with the control group. In the critically-ill group alpha- and beta-carotene were below detection limits for many patients. After adjusting for cholesterol, lycopene concentrations remained significantly lower (P<0.001) compared with the control group. In the critically-ill patients circulating concentrations of C-reactive protein and malondialdehyde were significantly correlated (r=0.502,P<0.01). CONCLUSIONS: The systemic inflammatory response is associated with increased lipid peroxidation and low carotenoid concentrations indicating that inflammation driven breakdown of carotenoids is an important factor in lowering circulating carotenoid concentrations in the critically-ill patient.

Adult↗
PubMed2001

Phacoemulsification combined with silicone oil removal through a posterior capsulorhexis.

PURPOSE: To evaluate the technique of silicone oil removal through a posterior capsulorhexis combined with phacoemulsification and intraocular lens (IOL) implantation. SETTING: Dr. Rajendra Prasad Center for Ophthalmic Sciences, New Delhi, India. METHODS: Fifteen eyes of 15 patients had phacoemulsification with removal of silicone oil, which had been used for intraocular tamponade after a previous pars plana vitrectomy. Eyes with a stable retina were included in the series. In all eyes, the silicone oil was removed through a planned posterior capsulorhexis after phacoemulsification. The parameters evaluated were the primary diagnosis, duration between silicone oil instillation and phacoemulsification, type of cataract, preoperative and postoperative best corrected visual acuities (BCVAs), and complications such as frequency of retinal redetachment and secondary cataract. RESULTS: Vitreoretinal surgery with silicone oil instillation was performed for rhegmatogenous-tractional detachment resulting from Eales' disease in 6 eyes and from proliferative diabetic retinopathy in 2 eyes, for primary rhegmatogenous retinal detachment in 6 eyes, and for traumatic rhegmatogenous detachment in 1 eye. The mean duration between the silicone oil instillation and phacoemulsification was 7.5 months +/- 3.8 (SD). Fourteen eyes had posterior subcapsular cataract, and 10 had nuclear sclerosis. Preoperative BCVA was worse than 6/60 in all eyes. The BCVA was 6/60 or better in 9 eyes after a minimum follow-up of 6 months. Two eyes had choroidal detachment in the early postoperative period. No eye had vitreous hemorrhage, retinal redetachment, secondary cataract, clinically significant endothelial decompensation or macular edema, or a dislocated IOL. CONCLUSION: The results indicate that silicone oil removal through a posterior capsulorhexis during phacoemulsification is a viable option and can be performed in selected cases of cataract with previous silicone oil instillation and a stable retina.

Adolescent↗
PubMed2001

Comparative study of vitrectomy for dropped nucleus with and without the use of perfluorocarbon liquid. Clinical, electrophysiological and visual field outcomes.

PURPOSE: To compare pars plana vitrectomy for dropped nucleus with and without perfluorocarbon liquid. METHODS: 24 eyes with dropped nucleus were randomized to undergo PPV with perfluorodecalin, (study, n=12) and without it (control, n=12). Visual acuity, IOP, visual evoked response and electroretinography were noted at study entry and up to 3 months after PPV. Humphrey perimetry was done at 3 months. RESULTS: Final visual acuity was >20/60 in 75% of study eyes and 41.6% of controls. The two groups were statistically comparable with regard to the above parameters before PPV and during follow-up. The timing of vitrectomy did not significantly influence the final visual acuity. A higher rate of complications was seen in the control group. CONCLUSIONS: Perfluorodecalin facilitated the procedure and possibly minimized complications, and was found to be safe for intraoperative use in terms of recovery of visual acuity, stable ERG and VER, and normal visual fields.

Adult↗
PubMed2001

Contrast sensitivity following focal laser photocoagulation in clinically significant macular oedema due to diabetic retinopathy.

PURPOSE: To evaluate the influence of focal aser photocoagulation on contrast sensitivity in diabetic patients with clinically significant macular oedema (CSMO). METHODS: A prospective non-comparative interventional study was performed on a group of patients with CSMO at Dr Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, a tertiary eye care centre. Thirteen diabetc patients (14 eyes) with CSMO and no history of prior photocoagulation were recruited for this study. Direct focal photocoagulation of all leaking microaneurysms was performed using an argon green laser (514 nm). A contact lens was used as a slit lamp delivery system. Evaluation of the best corrected Snellen visual acuity, contrast senstivity, slit lamp biomicroscopy, macular status on direct ophthalmoscopy and fluorescein angiography was carried out 1 month and 3 months after laser photocoagulation. RESULTS: Following direct focal laser photocoagulation, focal CSMO resolved completely in all but one eye, 4-8 weeks later, as seen on slit lamp biomicroscopy and/or fluorescein angiography. Post-treatment, visual acuity remained stationary in eight eyes, improved by one line in three eyes, by two lines in two eyes and by three lines in one eye. The mean +/- SD pretreatment and post-treatment decimal visual acuities were 0.49+/-0.30 and 0.59+/-0.28, respectively. The mean +/- SD pre-laser contrast sensitivity score was 121.3+/-83.6, which increased significantly to a mean +/- SD of 151.6+/-80.5 fo lowing direct focal photocoagulation. CONCLUSION: Focal argon laser photocoagulation in CSMO in diabetics helps in improving the contrast sensitivity and stabilizes the visual acuity. The changes in contrast sensitivity and visual acuity are independent of each other.

Contrast Sensitivity↗
PubMed2001

Enteroviral encephalitis leading to a locked-in state.

Millions of children are infected by enteroviruses each year, usually exhibiting only mild symptoms. Although enteroviruses are a common cause of community-acquired aseptic meningitis, enteroviral meningitis usually has a benign course. We describe a 14-year-old patient with enteroviral meningoencephalitis diagnosed by polymerase chain reaction. Her level of consciousness declined rapidly after hospital admission and resulted in a locked-in state. Although she experienced slow neurologic improvement, residual neurologic deficits remain. Although there is a general awareness of the characteristics of enteroviralencephalitis, this case report is significant in presenting a case of unusual severity and sequelae. To our knowledge, this is the first published report of an enterovirus encephalitis leading to a locked-in-state.

Adolescent↗
PubMed2000

Changes in micronutrient concentrations following anti-inflammatory treatment in patients with gastrointestinal cancer.

Circulating concentrations of vitamin antioxidants (retinol, alpha-tocopherol, lutein, lycopene, alpha- and beta-carotene) and trace elements (zinc, copper, iron and selenium) plus carrier proteins (albumin, transferrin, caeruloplasmin) in gastrointestinal cancer patients (n = 12) with an inflammatory response (as demonstrated by an elevated C-reactive protein concentration) were compared with a control group (n = 12). Further, the effect of moderating the inflammatory response, using the anti-inflammatory agent ibuprofen, on these measurements was examined in the cancer group. The control and cancer groups were similar in terms of age, sex, and body mass index. However, the cancer group had significantly higher C-reactive protein concentrations (P < 0.001). Concentrations of vitamin antioxidants and trace elements (and carrier proteins) were significantly lower (P < 0.001), except copper (ceruloplasmin) which was significantly higher (P < 0.05). After anti-inflammatory treatment, there were small but significant increases in lutein, lycopene, and beta-carotene (P < 0.05) and in iron and selenium (P < 0.05), whereas ceruloplasmin decreased (P < 0. 05). The micronutrient concentrations in the cancer patients remained different from those in the control subjects. These results support the concept that the magnitude of inflammation plays an important role in the regulation of circulating concentrations of vitamin antioxidants and trace elements in patients with gastrointestinal cancer.

Adrenal Cortex Hormones↗
PubMed2000

Relationship of carotenoid and vitamins A and E with the acute inflammatory response in acute pancreatitis.

BACKGROUND: Inflammation and oxidative stress are believed to be important in the development of the systemic complications of acute pancreatitis. The fat-soluble vitamins A and E, and the carotenoids have antioxidant properties. The aim of this study was to assess the effect of acute pancreatitis on serum concentrations of vitamin antioxidants and to relate such changes to the degree of the inflammatory response. METHODS: Thirteen consecutive patients with predicted severe acute pancreatitis were compared with 26 matched healthy controls. Five patients developed severe acute pancreatitis and three of these died. Vitamin antioxidant and C-reactive protein (CRP) levels were measured daily for up to 7 days. RESULTS: Patients had significantly lower levels of antioxidants throughout the course of the study (P < 0.017). In patients there was a significant correlation between peak CRP and trough antioxidant levels (P < 0. 01). In patients with mild acute pancreatitis, the concentrations of retinol and beta-carotene at final review were significantly higher than those in patients with severe acute pancreatitis (P < 0.05). This coincided with a reduction in CRP level. CONCLUSION: In acute pancreatitis, circulating concentrations of vitamin antioxidants are reduced and are inversely related to the rise in CRP level.

Acute Disease↗
PubMed2000

Vitamin B(1) status assessed by direct measurement of thiamin pyrophosphate in erythrocytes or whole blood by HPLC: comparison with erythrocyte transketolase activation assay.

BACKGROUND: The concentration of thiamin diphosphate (TDP) in erythrocytes is a useful index of thiamin status. We describe an HPLC method for TDP and its results in patients at risk of thiamin deficiency. METHODS: We used reversed-phase HPLC with postcolumn derivatization with alkaline potassium ferricyanide and fluorescence detection. Samples were deproteinized and injected directly onto a C(18) column. TDP concentrations in erythrocytes were compared with those in whole blood. Reference intervals for erythrocyte TDP (n = 147; 79 males and 68 females; mean age, 54 years) and whole blood TDP (n = 124; 68 males and 56 females; mean age, 54 years) were determined in an apparently healthy population. We compared erythrocyte TDP with results of the erythrocyte transketolase activation test in 63 patients who were considered at risk of thiamin deficiency. RESULTS: The method was linear to at least 200 microgram/L. The between-run CV was <8%. The lower limit of quantification for both whole blood and packed erythrocytes was 300 pg on column with a detection limit of 130 pg on column. Recovery of TDP from blood samples was >90%. TDP in erythrocytes correlated strongly with that in whole blood (r = 0.97). Reference intervals for erythrocyte and whole blood TDP were 280-590 ng/g hemoglobin and 275-675 ng/g hemoglobin, respectively. Of the 63 patients suspected of thiamin deficiency, 46 were normal by both TDP and activation tests, 13 were deficient by both tests, 1 was deficient by the activation test but had normal erythrocyte TDP concentrations, and 4 were normal by the activation test but had low TDP. CONCLUSIONS: The HPLC method is precise and yields results similar to the erythrocyte activation assay.

Chromatography, High Pressure Liquid↗
PubMed1999

Routine analysis of amphetamine class drugs as their naphthaquinone derivatives in human urine by high-performance liquid chromatography.

We describe a simple HPLC method which is suitable for the routine confirmation of immunoassay positive amphetamine urine samples. The precolumn derivisation method employing sodium naphthaquinone-4-sulphonate was found to have adequate sensitivity, selectivity and precision for the measurement of amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxyethylamphetamine (MDEA) at 500 microg/l cutoff level for confirmatory analysis of amphetamines in urine. The specificity of the method is enhanced by detecting the peaks at two different wavelengths. The ratios of the peak heights measured at the two wavelengths were different for each of the 5 amphetamines analysed. There was no interference from other phenylethylamine analogues that are commonly found in "over the counter" preparations. The HPLC method is compared to a commercial TLC system for detecting amphetamines in urine of drug abusers attending drug rehabilitation programmes. The HPLC confirmatory method described is a viable alternative to GC or to the more complex and costly GC-MS techniques for confirming amphetamine, methamphetamine, MDMA, MDA and MDEA in urine of drug abusers especially when used in a clinical care setting.

Amphetamines↗
PubMed1999

Dietary flavonols protect diabetic human lymphocytes against oxidative damage to DNA.

Diabetic patients have reduced antioxidant defenses and suffer from an increased risk of free radical-mediated diseases such as coronary heart disease. Epidemiological evidence has suggested that antioxidant dietary flavonoids may protect against heart disease, but a biological effect has yet to be demonstrated directly in humans. In this study, 10 stable type 2 diabetic patients were treated for 2 weeks on a low-flavonol diet and for 2 weeks on the same diet supplemented with 76-110 mg of flavonols (mostly quercetin) provided by 400 g of onions (and tomato sauce) and six cups of tea daily. Freshly collected lymphocytes were subjected to standard oxidative challenge with hydrogen peroxide, and DNA damage was measured by single-cell gel electrophoresis. Fasting plasma flavonol concentrations (measured by high-performance liquid chromatography) were 5.6 +/- 2.9 ng/ml on the low-flavonol diet and increased 12-fold to 72.1 +/- 15.8 ng/ml on the high-flavonol diet (P < 0.001). Oxidative damage to lymphocyte DNA was 220 +/- 12 on an arbitrary scale of 0-400 U on the low-flavonol diet and 192 +/- 14 on the high-flavonol diet (P = 0.037). This decrease was not accounted for by any change in the measurements of diabetic control (fasting plasma glucose or fructosamine) or by any change in the plasma levels of known antioxidants, including vitamin C, carotenoids, alpha-tocopherol, urate, albumin, and bilirubin. In conclusion, we have shown a biological effect of potential medical importance that appears to be associated with the absorption of dietary flavonols.

Aged↗
PubMed1998

A routine method for the simultaneous measurement of retinol, alpha-tocopherol and five carotenoids in human plasma by reverse phase HPLC.

We describe a simple isocratic HPLC method for the accurate and precise measurement of retinol, alpha-tocopherol and the major carotenoids in plasma using UV detection. Reference ranges for retinol, alpha-tocopherol and five carotenoids are determined in a healthy population group. The most abundant carotenoids found in plasma were beta-carotene, lycopene, lutein and cryptoxanthin. Retinol, alpha-tocopherol and carotenoids were determined simultaneously using two internal standards, retinol acetate for retinol and tocopherol acetate for alpha-tocopherol and carotenoids. The use of echinenone as an internal standard for carotenoids was investigated. The protective effect of an antioxidant (ascorbic acid) on the stability of samples and extracted material is documented. The method is useful for the routine measurement of plasma retinol, alpha-tocopherol and carotenoids and could also be used in large scale epidemiological studies.

Adult↗
PubMed1998

Mutations in the EF-hand motif impair the inactivation of barium currents of the cardiac alpha1C channel.

Calcium-dependent inactivation has been described as a negative feedback mechanism for regulating voltage-dependent calcium influx in cardiac cells. Most recent evidence points to the C-terminus of the alpha1C subunit, with its EF-hand binding motif, as being critical in this process. The EF-hand binding motif is mostly conserved between the C-termini of six of the seven alpha1 subunit Ca2+ channel genes. The role of E1537 in the C-terminus of the alpha1C calcium channel inactivation was investigated here after expression in Xenopus laevis oocytes. Whole-cell currents were measured in the presence of 10 mM Ba2+ or 10 mM Ca2+ after intracellular injection of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. Against all expectations, our results showed a significant reduction in the rate of voltage-dependent inactivation as measured in Ba2+ solutions for all E1537 mutants, whereas calcium-dependent inactivation appeared unscathed. Replacing the negatively charged glutamate residue by neutral glutamine, glycine, serine, or alanine significantly reduced the rate of Ba2+-dependent inactivation by 1.5-fold (glutamine) to 3.5-fold (alanine). The overall rate of macroscopic inactivation measured in Ca2+ solutions was also reduced, although a careful examination of the distribution of the fast and slow time constants suggests that only the slow time constant was significantly reduced in the mutant channels. The fast time constant, the hallmark of Ca2+-dependent inactivation, remained remarkably constant among wild-type and mutant channels. Moreover, inactivation of E1537A channels, in both Ca2+ and Ba2+ solutions, appeared to decrease with membrane depolarization, whereas inactivation of wild-type channels became faster with positive voltages. All together, our results showed that E1537 mutations impaired voltage-dependent inactivation and suggest that the proximal part of the C-terminus may play a role in voltage-dependent inactivation in L-type alpha1C channels.

Amino Acid Sequence↗
PubMed1998

Assessment of status.

Laboratory methods for the measurement of micronutrients are usually based upon determinations in the peripheral blood. Most are relatively insensitive, but can screen for impending acute deficiency or toxicity. The metabolic responses to disease, injury and infection may alter the laboratory findings independently of dietary supply. Methods based upon the intra-cellular biochemical function of individual micronutrients are becoming available and can detect more marginal deficiencies. The investigation of general populations for micronutrient depletions largely relies upon clinical and epidemiological evaluation of responses to controlled trials of supplementation.

Clinical Laboratory Techniques↗
PubMed1997

Subunit regulation of the human brain alpha 1E calcium channel.

The alpha1 subunit coding for the human brain type E calcium channel (Schneider et al., 1994) was expressed in Xenopus oocytes in the absence, and in combination with auxiliary alpha2delta and beta subunits. alpha1E channels directed with the expression of Ba2+ whole-cell currents that completely inactivated after a 2-sec membrane pulse. Coexpression of alpha1E with alpha2bdelta shifted the peak current by +10 mV but had no significant effect on whole-cell current inactivation. Coexpression of alpha1E with beta2a shifted the peak current relationship by -10 mV, and strongly reduced Ba2+ current inactivation. This slower rate of inactivation explains that a sizable fraction (40 +/- 10%, n = 8) of the Ba2+ current failed to inactivate completely after a 5-sec prepulse. Coinjection with both the cardiac/brain beta2a and the neuronal alpha2bdelta subunits increased by approximately 10-fold whole-cell Ba2+ currents although coinjection with either beta2a or alpha2bdelta alone failed to significantly increase alpha1E peak currents. Coexpression with beta2a and alpha2bdelta yielded Ba2+ currents with inactivation kinetics similar to the beta2a induced currents, indicating that the neuronal alpha2bdelta subunit has little effect on alpha1E inactivation kinetics. The subunit specificity of the changes in current properties were analyzed for all four beta subunit genes. The slower inactivation was unique to alpha1E/beta2a currents. Coexpression with beta1a, beta1b, beta3, and beta4, yielded faster-inactivating Ba2+ currents than currents recorded from the alpha1E subunit alone. Furthermore, alpha1E/alpha2bdelta/beta1a; alpha1E/alpha2bdelta/beta1b; alpha1E/alpha2bdelta/beta3; alpha1E/alpha2bdelta/beta4 channels elicited whole-cell currents with steady-state inactivation curves shifted in the hyperpolarized direction. The beta subunit-induced changes in the properties of alpha1E channel were comparable to modulation effects reported for alpha1C and alpha1A channels with beta3 approximately beta1b > beta1a approximately beta4 >> beta2a inducing fastest to slowest rate of whole-cell inactivation.

Animals↗
PubMed1997

Acute-phase reactants and plasma trace element concentrations in non-small cell lung cancer patients and controls.

This study examined the effect of an acute-phase response on plasma trace element concentrations of non-small cell lung cancer (NSCLC) patients. In normal subjects (n = 13) and NSCLC patients (n = 22), fasting concentrations of albumin, C-reactive protein, the trace elements iron, zinc, copper, and selenium, and their associated proteins transferrin, albumin, ceruloplasmin, and glutathione peroxidase were measured. The NSCLC patients were subdivided into two equal groups depending on whether they had a C-reactive protein concentration < 35 mg/l (Group 1) or > 35 mg/l (Group 2). Circulating zinc, iron, and transferrin concentrations were significantly lower in NSCLC Group 1 than in the control group (p < 0.05). Circulating concentrations of iron, zinc, and the binding proteins transferrin and albumin were significantly lower in NSCLC Group 2 than in the control group and NSCLC Group 1 (zinc not significantly different) (p < 0.01). In contrast circulating concentrations of copper and its binding protein ceruloplasmin were significantly increased in NSCLC Group 2 compared with NSCLC Group 1 and the control group (p < 0.01). Additionally, plasma selenium and glutathione peroxidase concentrations were significantly lower (p < 0.05) in NSCLC Group 2 than in NSCLC Group 1 and the control group. In the NSCLC patients there were significant negative correlations between concentrations of C-reactive protein and iron, transferrin, zinc, albumin, and selenium (p < 0.05). Furthermore, there were also significant positive correlations between C-reactive protein and copper (r = 0.788, p < 0.001) and ceruloplasmin (r = 0.831, p < 0.001) concentrations. The presence of an acute-phase response has implications for the interpretation of circulating trace element concentrations, the status of patients with NSCLC, and supplementation with trace elements in patients with NSCLC.

Acute-Phase Proteins↗
PubMed1997

Effect of inflammation on measures of antioxidant status in patients with non-small cell lung cancer.

This study examined the effect of an inflammatory response on measures of antioxidant status in patients with non-small cell lung cancer (NSCLC). In healthy, control subjects (n = 13) and NSCLC patients (n = 22) fasting concentrations of albumin, C-reactive protein, cholesterol, and the antioxidants alpha-tocopherol, retinol, lutein, lycopene, and alpha- and beta-carotene were measured. The two groups were similar in terms of age, sex, and body mass index. However, the cancer group had an inflammatory response as evidenced by significantly increased C-reactive protein concentrations. Concentrations of all the measured antioxidants of the NSCLC group were significantly lower than those of the control group (P < 0.01). The lowest concentrations were those of the carotenoids lycopene and alpha- and beta-carotene. In the cancer group there were significant negative correlations between concentrations of C-reactive protein and retinol (r = -0.682, P < 0.01), alpha-tocopherol (r = -0.464, P < 0.05), and lutein (r = -0.599, P < 0.01). The results of this study have implications for the interpretation of circulating antioxidant concentrations in patients with NSCLC.

Aged↗
PubMed1997

Endogenous cortisol profile in patients with central serous chorioretinopathy.

AIM: To study the endogenous cortisol levels in patients with central serous chorioretinopathy (CSCR). METHODS: Endogenous cortisol levels in urine and plasma were determined in 30 patients with acute CSCR and compared with 30 age and sex matched controls. RESULTS: The mean values of the 8 am plasma cortisol (29.97 micrograms/dl v 18.76 micrograms/dl), 11 pm plasma cortisol (22.03 micrograms/dl v 13.06 micrograms/dl), and 24 hour urine cortisol (11.01 mg/24 h v 7.39 mg/24 h) revealed significantly higher values in the patient group (p < 0.001). CONCLUSIONS: Increased levels of endogenous cortisol are present in patients with CSCR.

Adult↗