Reduction of nausea, vomiting, and dry retches with P6 acupressure during pregnancy.
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Acupressure↗
Biomedical subjects
K Ramanathan
Publications and source records attributed to K Ramanathan.
Protective role of ascorbic acid and alpha-tocopherol on arsenic-induced microsomal dysfunctions.
Arsenic, a naturally occurring element, is present in food, soil, air and water. All human populations are exposed to arsenic and its compounds through occupational or environmental processes. Since arsenic compounds have been shown to exert their toxicity chiefly by generating reactive oxygen species, we have evaluated the effect of ascorbic acid and alpha-tocopherol on oxidative damage, antioxidant status and on xenobiotic metabolizing systems in arsenic-exposed rat liver and kidney microsomes. Arsenic exposure increases oxidative damage to lipids and proteins and decreases the levels of antioxidants and the activities of xenobiotic metabolizing enzymes. Coadministration of ascorbic acid and alpha-tocopherol to arsenic-exposed rats resulted in a reduction in the levels of lipid peroxidation, protein carbonyls and hydrogen peroxide and an elevation in the levels of reduced glutathione, ascorbic acid and alpha-tocopherol. Ascorbic acid and alpha-tocopherol treatment decreases the activity of haem oxygenase, whereas it increases the levels/ activity of cytochrome P450, cytochrome b5 and NADPH-cytochrome P450 reductase in arsenic-intoxicated rats. The results of this study provide evidence that ascorbic acid and alpha-tocopherol supplementation can improve the arsenic-induced altered microsomal functions in liver and kidney.
Animals↗
Effects of ascorbic acid and alpha-tocopherol on arsenic-induced oxidative stress.
Arsenic is an ubiquitous element in the environment causing oxidative burst in the exposed individuals leading to tissue damage. Antioxidants have long been known to reduce the free radical-mediated oxidative stress. Therefore, the present study was designed to determine whether supplementation of alpha-tocopherol (400 mg/kg body weight) and ascorbic acid (200 mg/kg body weight) to arsenic-intoxicated rats (100 ppm in drinking water) for 30 days affords protection against the oxidative stress caused by the metalloid. The arsenic-treated rats showed elevated levels of lipid peroxide, decreased levels of non-enzymatic antioxidants and activities of enzymatic antioxidants. Administration of alpha-tocopherol and ascorbic acid to arsenic-exposed rats showed a decrease in the level of lipid peroxidation (LPO) and enhanced levels of total sulfhydryls, reduced glutathione, ascorbic acid and alpha-tocopherol and so do the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase to near normal. These findings suggest that alpha-tocopherol and ascorbic acid prevent LPO and protect the antioxidant system in arsenic-intoxicated rats.
Administration, Oral↗
Effect of DL-alpha-lipoic acid on mitochondrial enzymes in aged rats.
Mitochondrial dysfunction appears to contribute to some of the loss of function accompanying ageing. Mitochondria from aged tissue use oxygen inefficiently impairing ATP synthesis and results in increased oxidant production. A high flux of oxidants not only damages mitochondria, but other important cell biomolecules as well. In the present investigation, the levels of lipid peroxidation, oxidized glutathione, non-enzymatic antioxidants and the activities of mitochondrial enzymes were measured in liver and kidney mitochondria of young and aged rats before and after lipoic acid supplementation. In both liver and kidney increase in the levels of mitochondrial lipid peroxidation and oxidized glutathione and decrease in the levels of antioxidants and the activities of mitochondrial enzymes were observed in aged rats. DL-alpha-lipoic acid supplemented aged rats showed a decrease in the levels of lipid peroxidation and oxidized glutathione and increase in the levels of reduced glutathione, vitamins C and E and the activities of mitochondrial enzymes like isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, NADH-dehydrogenase and cytochrome-c-oxidase. Thus, lipoic acid reverses the age-associated decline in endogenous low molecular weight antioxidants and mitochondrial enzymes and, therefore, may lower the increased risk of oxidative damage that occurs during ageing. From our results it can be concluded that lipoic acid supplementation enhances the activities of mitochondrial enzymes and antioxidant status and thereby protects mitochondria from ageing.
Aging↗
Kangaroo Mother Care in very low birth weight infants.
OBJECTIVE: This study was conducted (i) to study through a randomized control trial the effect of Kangaroo Mother Care (KMC) on breast feeding rates, weight gain and length of hospitalization of very low birth neonates and (ii) to assess the acceptability of Kangaroo Mother Care by nurses and mothers. METHODS: Babies whose birth weight was less than 1500 Grams were included in the study once they were stable. The effect of Kangaroo Mother Care on breast feeding rates, weight gain and length of hospitalization of very low birth weight neonates was studied through a randomized control trial in 28 neonates. The Kangaroo group (n = 14) was subjected to Kangaroo Mother Care of at least 4 hours per day in not more than 3 sittings. The babies received Kangaroo Care after shifting out from NICU and at home. The control group (n = 14) received only standard care (incubator or open care system). Attitude of mothers and nurses towards KMC was assessed on Day 3 +/- 1 and on day 7 +/- 1 after starting Kangaroo Care in a questionnaire using Likert's scale. RESULTS: The results of the clinical trial reveal that the neonates in the KMC group demonstrated better weight gain after the first week of life (15.9 +/- 4.5 gm/day vs. 10.6 +/- 4.5 gm/day in the KMC group and control group respectively p < 0.05) and earlier hospital discharge (27.2 +/- 7 vs. 34.6 +/- 7 days in KMC and control group respectively, p < 0.05). The number of mothers exclusively breastfeeding their babies at 6 week follow-up was double in the KMC group than in the control group (12/14 vs. 6/14) (p < 0.05). CONCLUSION: KMC managed babies had better weight gain, earlier hospital discharge and, more impressively, higher exclusive breast-feeding rates. KMC is an excellent adjunct to the routine preterm care in a nursery.
Adult↗
Effect of DL-alpha-lipoic acid on glutathione metabolic enzymes in aged rats.
Ageing is characterized by a failure to maintain homeostasis under conditions of physiological stress, with an increasing susceptibility to disease and death. The accumulation of errors committed by faulty biochemical reactions over a vast period generates the cumulative effect observed during ageing. The most notable among the effects of ageing are the age-related disorders where free radicals are the major cause. When the level of free radicals increases because of diet, lifestyle, environment or other influences, it results in subsequent reduction of antioxidants. Reduced glutathione is one of the most fascinating molecules virtually present in all animal cells in often quite higher concentrations. An essential mechanism that accounts for most of the metabolic and cell regulatory properties of glutathione is the thiol disulfide exchange equilibria. We evaluated the age-associated alterations in glutathione dependent enzymes, glutathione and hydroxyl radicals in young and aged rats with respect to lipoate supplementation. In aged rats, activities of glutathione peroxidase, glutathione reductase, glutathione-S-transferase and glucose-6-phosphate dehydrogenase and the level of glutathione were low, whereas the level of hydroxyl radical was higher than in the young ones. Administration of DL-alpha-lipoic acid, a thiol antioxidant intraperitoneally to the aged rats, led to a time-dependent reduction in hydroxyl radicals and elevation in the activities/level of glutathione systems. Hence it can be suggested that lipoate, a dithiol prevents the oxidation of reduced glutathione and protects its related enzymes from peroxidative damage.
Aging↗
Percutaneous coronary intervention versus coronary artery bypass graft surgery for patients with medically refractory myocardial ischemia and risk factors for adverse outcomes with bypass: a multicenter, randomized trial. Investigators of the Department of Veterans Affairs Cooperative Study #385, the Angina With Extremely Serious Operative Mortality Evaluation (AWESOME).
BACKGROUND: Percutaneous coronary intervention (PCI) and coronary artery bypass graft surgery (CABG) are being applied to high-risk populations, but previous randomized trials comparing revascularization methods have excluded a number of important high-risk groups. OBJECTIVES: This five-year, multicenter, randomized clinical trial was designed to compare long-term survival among patients with medically refractory myocardial ischemia and a high risk of adverse outcomes assigned to either a CABG or a PCI strategy, which could include stents. METHODS: Patients from 16 Veterans Affairs Medical Centers were screened to identify myocardial ischemia refractory to medical management and the presence of one or more risk factors for adverse outcome with CABG, including prior open-heart surgery, age >70 years, left ventricular ejection fraction <0.35, myocardial infarction within seven days or intraaortic balloon pump required. Clinically eligible patients (n = 2,431) underwent coronary angiography; 781 were angiographically acceptable; 454 (58% of eligible) patients consented to random assignment between CABG and PCI. RESULTS: A total of 232 patients was randomized to CABG and 222 to PCI. The 30-day survivals for CABG and PCI were 95% and 97%, respectively. Survival rates for CABG and PCI were 90% versus 94% at six months and 79% versus 80% at 36 months (log-rank test, p = 0.46). CONCLUSIONS: Percutaneous coronary intervention is an alternative to CABG for patients with medically refractory myocardial ischemia and a high risk of adverse outcomes with CABG.
Aged↗
Effect of DL-alpha-lipoic acid on the status of lipid peroxidation and antioxidants in mitochondria of aged rats.
The life span of a species is thought to be determined by the rate of mitochondrial damage which in turn is inflicted by free radicals in the mitochondria during the course of normal metabolism. The level of lipid peroxidation and antioxidants were measured in liver and kidney mitochondria of young and aged rats before and after DL-alpha-lipoic acid supplementation. In both liver and kidney, mitochondrial lipid peroxidation increased with age and a decrease in the enzymatic and non-enzymatic antioxidants were observed. DL-alpha-lipoic acid treated aged rats showed a decrease in the level of lipid peroxides and an increase in the antioxidant status. Our results conclude that supplementation of lipoic acid restores the depleted mitochondrial antioxidant status and suggest that it could be an effective therapeutic agent in treatment of age-associated disorders where free radicals are the major causative factor.
Journal Article↗
Principles and applications of thermal biosensors.
A review of thermistor-based calorimetric measurement is presented. The principles of thermometric measurements are highlighted in the introduction followed by the instrumentation, materials and methods. Various applications relating to enzyme activity measurements, clinical monitoring, process monitoring, multianalyte determination, hybrid sensing, environmental monitoring, non-aqueous measurements and other miscellaneous applications are described. A brief note on future developments and a detailed reference list is also included.
Biological Factors↗
Ameliorating contrast-induced nephropathy.
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Aminophylline↗
Thermometric sensing of peroxide in organic media. Application to monitor the stability of RBP-retinol-HRP complex.
The stability of horseradish peroxidase (HRP) in aqueous and organic solvents is applied to develop a simple thermometric procedure to detect the binding of retinoic acid-HRP conjugate to retinol binding protein (RBP). Butanone peroxide (BP) in organic phase and hydrogen peroxide in aqueous phase is detected thermometrically on a HRP column, immobilized by cross-linking with glutaraldehyde on controlled pore glass (CPG). Acetone, acetonitrile, methanol, and 2-butanol are used for detection of BP, in the flow injection analysis (FIA) mode. A linear range between 1 and 50 mM BP is obtained in all the organic solvents with a precision of 5-7% (CV%). The magnitude and nature of the thermometric response is significantly different in each organic solvent. The stability of HRP in the organic phase is used to study the stability of a retinoic acid-HRP conjugate bound to immobilized RBP. The response of HRP (to 20 mM BP) in the retinoic acid-HRP conjugate is used as an indicator of the stability of the RBP-retinoic acid-HRP complex, after challenges with various organic/aqueous solvents. Both immobilized HRP and RBP are stable at least for 6 months. The effect of o-phenylene diamine on the thermometric response of HRP is also investigated. A scheme for the design of a thermometric retinol (vitamin A) biosensor is proposed.
Calibration↗
beta subunits modulate alternatively spliced, large conductance, calcium-activated potassium channels of avian hair cells.
Electrical tuning confers frequency selectivity onto sensory hair cells in the auditory periphery of frogs, turtles, and chicks. The resonant frequency is determined in large part by the number and kinetics of large conductance, calcium-activated potassium (BK) channels. BK channels in hair cells are encoded by the alternatively spliced slo gene and may include an accessory beta subunit. Here we examine the origins of kinetic variability among BK channels by heterologous expression of avian cochlear slo cDNAs. Four alternatively spliced forms of the slo-alpha gene from chick hair cells were co-expressed with accessory beta subunits (from quail cochlea) by transient transfection of human embryonic kidney 293 cells. Addition of the beta subunit increased steady-state calcium affinity, raised the Hill coefficient for calcium binding, and slowed channel deactivation rates, resulting in eight functionally distinct channels. For example, a naturally occurring splice variant containing three additional exons deactivated 20-fold more slowly when combined with beta. Deactivation kinetics were used to predict tuning frequencies and thus tonotopic location if hair cells were endowed with each of the expressed channels. All beta-containing channels were predicted to lie within the apical (low-frequency) 30% of the epithelium, consistent with previous in situ hybridization studies. Individual slo-alpha exons would be found anywhere within the apical 70%, depending on the presence of beta, and other alternative exons. Alternative splicing of the slo-alpha channel message provides intrinsic variability in gating kinetics that is expanded to a wider range of tuning by modulation with beta subunits.
Alternative Splicing↗
Surface plasmon resonance based pesticide assay on a renewable biosensing surface using the reversible concanavalin A monosaccharide interaction.
A competitive immunoassay based on surface plasmon resonance (SPR) for the detection of the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) is reported. The novelty of the assay is based on the regeneration of the chip surface by the reversible interaction between monosaccharide (D-glucose) and lectin (Concanavalin A). Concanavalin A-2,4-D conjugate was chemically synthesized, purified and used for binding to the SPR chip modified with covalently bound alpha-D-glucose. The interaction between anti-2,4-D antibody and the surface-bound concanavalin A-2,4-D conjugate was monitored by surface plasmon resonance and the response was used for the quantification of 2,4-D. The dynamic range of the calibration curve was between 3 and 100 ng/ml. The demonstrated principle of surface regeneration based on the reversible sugar-lectin interaction may be of more general applicability in immunoassays.
2,4-Dichlorophenoxyacetic Acid↗
High-sensitivity assay for pesticide using a peroxidase as chemiluminescent label.
The application of a newly isolated transgenic tobacco peroxidase (TOP) as a chemiluminescent label for immunoassay purposes is described for the first time. The enzyme has been oxidized with m-periodate and subsequently coupled to the model compound 2,4-dichlorophenoxyacetic acid (2,4-D) using a carbodiimide method. As compared to the native horseradish peroxidase used in control experiments, the TOP enzyme showed significantly higher efficiency of coupling to the antigen and no loss of the specific activity was observed. The obtained 2,4-D-TOP conjugate demonstrated unique properties in chemiluminescent detection. The latter allowed the minimization of the conjugate concentration due to the superior chemiluminescent activity of the enzyme. A highly sensitive capillary chemiluminescent immunoassay using the 2,4-D-TOP conjugate as labeled competitor is reported. Direct competitive ELISA has been performed using a specific monoclonal antibody immobilized onto the sol-gel treated glass capillary surface. A modified photomultiplier tube with a special holder for a capillary was used for the resulting chemiluminescent signal detection. The typical standard calibration curve for the 2,4-D pesticide detection is linear between 30 pg and 500 ng/mL.
2,4-Dichlorophenoxyacetic Acid↗
A molecular mechanism for electrical tuning of cochlear hair cells.
Cochlear frequency selectivity in lower vertebrates arises in part from electrical tuning intrinsic to the sensory hair cells. The resonant frequency is determined largely by the gating kinetics of calcium-activated potassium (BK) channels encoded by the slo gene. Alternative splicing of slo from chick cochlea generated kinetically distinct BK channels. Combination with accessory beta subunits slowed the gating kinetics of alpha splice variants but preserved relative differences between them. In situ hybridization showed that the beta subunit is preferentially expressed by low-frequency (apical) hair cells in the avian cochlea. Interaction of beta with alpha splice variants could provide the kinetic range needed for electrical tuning of cochlear hair cells.
Alternative Splicing↗
Principles of enzyme thermistor systems: applications to biomedical and other measurements.
This chapter presents an overview of thermistor-based calorimetric measurements. Bioanalytical applications are emphasized from both the chemical and biomedical points of view. The introductory section elucidates the principles involved in the thermometric measurements. The following section describes in detail the evolution of the various versions of enzyme-thermistor devices. Special emphasis is laid on the description of modern "mini" and "miniaturized" versions of enzyme thermistors. Hybrid devices are also introduced in this section. In the sections on applications, the clinical/biomedical areas are dealt with separately, followed by other applications. Mention is also made of miscellaneous applications. A special section is devoted to future developments, wherein novel concepts of telemedicine and home diagnostics are highlighted. The role of communication and information technology in telemedicine is also mentioned. In the concluding sections, an attempt is made to incorporate the most recent references on specific topics based on enzyme-thermistor systems.
Biosensing Techniques↗
An enzyme thermistor-based assay for total and free cholesterol.
A method to evaluate the free (FC) and total cholesterol (TC) in human serum, bile and gallstone extract using an enzyme thermistor (ET)-based flow injection analysis (FIA) is presented. The cholesterol in high-density (HDL-C) and low density lipoprotein (LDL-C) have also been evaluated. A heparin functionalized Sepharose column was employed for the isolation of HDL and LDL fractions from serum. The estimation of cholesterol and its esters was based on their reaction with cholesterol oxidase (CO), cholesterol esterase (CE) and catalase (CAT). Three different enzyme columns, i.e. co-immobilized CO/CAT (column A), only CE (column B) and co-immobilized CO/CE/CAT (column C) were prepared by cross-linking the enzymes on glass beads using glutaraldehyde. Column A was used for estimating FC and column C was used for estimating total cholesterol (cholesterol plus esterified cholesterol). Column B was used as a pre-column which could be switched 'in' or 'out' in conjunction with column A for the estimation of TC or FC, respectively. A calibration between 1.0 and 8.0 mmol/l for FC and 0. 25 and 4.0 mmol/l for TC was obtained. For more than 2000 assays with the ET device a C.V. of less than 4% was obtained. The assay time was approximately 4 min per assay. The cholesterol estimations on the ET correlated well with similar estimations using a commercially available cholesterol diagnostic kit.
Biosensing Techniques↗
The development and applications of thermal biosensors for bioprocess monitoring.
Enzyme thermistors are biosensors that use thermal resistors to measure the heat change caused by an enzymatic reaction. They combine the selectivity of enzymes with the sensitivity of biosensors and allow continuous analysis in a flow-injection mode. They can be used to monitor fermentation systems, biocatalysis, enzyme-catalysed synthesis and clinical and food technology. This article gives an overview of the general principles of enzyme thermistors, the sampling process and the ongoing developments in the field of bioprocess monitoring.
Automation↗