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Biomedical subjects

I Das

Publications and source records attributed to I Das.

At least 37 records · Page 2Linked to original sources
PubMed1998

Nitric oxide, free radicals and polyamines may have a role in the membrane pathology of schizophrenia.

Studies on skin fibroblasts in culture derived from schizophrenic and control subjects showed that polyamines are increased, nitrate levels are reduced and thiobarbituric acid reacting substances did not alter in cultured cells from schizophrenic patients compared to control subjects. Results seem to indicate some alteration in membrane functions in schizophrenia, which is susceptible to neuroleptic treatment. Significantly increased levels of polyamines in drug-treated schizophrenic cells indicates a possible role of polyamines in the activation of proposed hypofunctional NMDA subtype of glutamate receptor systems in schizophrenia.

Adolescent↗
PubMed1997

Liesegang Ring Type Structures and Bifurcation in Solid-Vapor and Liquid Phase Reactions between Cobalt Nitrate and Ammonium Hydroxide

New results on the reaction between (i) cobalt nitrate (A) and ammonium hydroxide (B) in gelatin and (ii) cobalt nitrate (solid) and ammonia vapor are reported. Spatial bifurcation of the blue wave into a number of normal Liesegang type bands is observed in a one-dimensional tube in gel media depending on the concentration of electrolytes and gel. Similar bifurcation is also observed when the reaction was carried out in gel media between two microslides. Results show that Ksp (solubility product), as envisaged in recent theories, plays a significant role in initiating bifurcation depending on K, the magnitude of the product of concentration of A and B, which determines the degree of supersaturation. The value of K at the instant of bifurcation, when (i) concentration of Co(NO3)2 is alone changed or when (ii) concentration of NH4OH alone is changed, is similar when uncertainties are taken into account. The bifurcation behavior when gel concentration is changed suggests that in case of high gel concentration pore size is affected, thereby influencing the diffusion of ions. The results satisfy the spacing law. The results further satisfy the relation d2 = m't + C' at any time t, where d is the distance between the lower front of the precipitate and the junction and m' and C' are constants, thereby suggesting that the role of diffusion is vital, as envisaged in various theories of the phenomenon. A colored banded structure separated by air gaps (vacant spaces) is formed when the solid cobalt nitrate reacts with ammonia vapor. This type of behavior has not been reported earlier. Initially, a single band is formed in a one-dimensional experiment, but in the course of time ( approximately 1 month) several bands are formed simultaneously. The diffusion kinetics in the initial stages of the solid-vapor reaction has been studied in a one-dimensional tube. The data obey the relation xi2 = kt, where xi is the thickness of the product layer at any time t and k is some constant. Similar studies were made on microslides which showed that during the reaction, a colored product is formed which undergoes change in the sequence pink --> blue --> brown. Results in the one-dimensional case support recent theories which postulate nucleation followed by aggregation. Copyright 1997Academic Press

Journal Article↗
PubMed1997

A pivotal role for glutamate in the pathogenesis of schizophrenia, and its cognitive dysfunction.

There is mounting evidence of a glutamate dysfunction in schizophrenia, as suggested by the fact that schizophrenia and phencyclidine psychosis are similar and phencyclidine is known to block the N-methyl-D-aspartate (NMDA) subtypes of glutamate. Both occur mainly after puberty, suggesting they may share similar underlying developmental processes. Direct evidence is now accumulating from the study of messenger RNA that glutamate receptor deficiencies occur in schizophrenia and are regionally and specifically distributed. These results find support from studies of memory, electrophysiological findings, clinical treatment, and pharmacological studies in mammals and humans. Our recent findings of: a) a marked decrease in pyramidal cell dendritic spines in layer III of the frontal and temporal cortex, and b) a greater than 0.90 correlation between decrease in mRNA for the NMDA glutamate receptor and cognitive deterioration in elderly schizophrenics, present the strongest evidence to date that glutamate dysfunction plays an important role in schizophrenia.

Animals↗
PubMed1997

Central venous catheter-related septicaemia in paediatric cancer patients.

A prospective study of septicaemia, with special reference to central venous catheter (CVC)-related septicaemia, was performed over a nine-month period in paediatric cancer patients undergoing anti-neoplastic therapy. A total of 142 patients with 153 CVCs were included in the study. Seventy-two episodes of septicaemia were detected in 66 patients; overall, 46% of patients developed one or more episodes of septicaemia. Thirty-nine (54%) of these episodes occurring in 34 patients were CVC-related. Twenty-one (29%) of the episodes occurring in twenty patients were probably unrelated to CVCs and 12 (17%) episodes in 12 patients were of uncertain source. A total of 22932 CVC days were studied. The rate of CVC-related septicaemia was 1.7 episodes/1000 catheter days. Gram-positive organisms were commonest, causing 34 (87%) episodes of CVC-related septicaemia. Twenty-five (71%) of 35 evaluable episodes were successfully treated with antibiotics without CVC removal. Two patients died, CVC related sepsis probably contributing to death, and one patient suffered prolonged morbidity associated with CVC sepsis. Gram-negative organisms were the commonest cause of CVC-unrelated septicaemia, being implicated in 13 (62%) episodes.

Adolescent↗
PubMed1997

How useful are microbial filters in respiratory apparatus?

Following an outbreak of hepatitis C in surgical patients in Australia, it has been suggested that transmission can take place as a result of contaminated anaesthetic circuits. It has therefore been recommended that filters should be placed between patients and breathing systems with a new filter being used for each patient. Although nosocomial pneumonia is a major manifestation of hospital-acquired infection, it is unclear whether contamination of ventilator circuits is implicated in the aetiology of this condition. Some data suggest that bacteria cannot survive well in anaesthetic circuits and several studies have failed to demonstrate significant contamination of circuits in clinical situation. Several outbreaks of pneumonia related to contaminated anaesthetic equipment have been described, but many of these were controlled by appropriate decontamination of the respiratory equipment. Although ventilator filters are used by the majority of intensive care units and filters do have the ability to filter bacteria and viruses, there are few data suggesting that the use of filters reduce the rate of pulmonary infections in long-term ventilated patients. Furthermore, to change filters between operations would have significant financial implications, and there is no conclusive evidence that they would reduce cross infection. Until more data are available on the role of filters in both long-term ventilated patients and operations, standard hygienic measures such as appropriate disinfection protocols are still the most effective way of reducing ventilator-associated infections.

Cross Infection↗
PubMed1997

Endocarditis caused by Haemophilus parainfluenzae identified by 16S ribosomal RNA sequencing.

Haemophilus parainfluenzae, a human commensal, is an infrequent cause of serious disease. A case of endocarditis caused by this organism in a five year old boy with complex congenital heart disease is reported. The course of this disease was very aggressive, leading to heart failure, disseminated intravascular coagulation and multiorgan failure in spite of appropriate antibiotics and surgical intervention. The difficulties in the detection and identification of H parainfluenzae using conventional culture based technology, and the potential role of molecular techniques, are highlighted.

Anti-Bacterial Agents↗
PubMed1997

Hypothalamic hypertensive factor: an inhibitor of nitric oxide synthase activity.

Human and rat plasma and rat hypothalamus contain a cytochemically detectable substance, the concentration of which rises with an increase in salt intake. The plasma concentration of this material is also raised in essential hypertension and in the spontaneously hypertensive rat (SHR), the Milan hypertensive rat, and the reduced renal mass (RRM) hypertensive rat. In the normal rat, the greatest concentration is found in the hypothalamus of the SHR and the RRM hypertensive rat. The physicochemical characteristics of this cytochemically detectable hypothalamic hypertensive factor (HHF), including chromatographic behavior and molecular weight range, suggest that it may share features common to a substituted guanidine that is present in established nitric oxide synthase (NOS) inhibitors. It was therefore decided to determine the effect on NOS activity of the HHF obtained from mature SHR. The ability of HHF to inhibit NOS activity was studied on (1) NOS extracted from bovine aorta, rat brain, and human platelets by measuring the conversion of radiolabeled L-arginine to L-citrulline and (2) rat liver NOS measured indirectly with a cytochemical technique based on the stimulation of soluble guanylate cyclase activity in hepatocytes by NO. HHF showed a biphasic inhibitory action on platelet NOS activity that was greater with HHF obtained from SHR than from Wistar-Kyoto rats. HHF also had a biphasic inhibitory effect on hepatocyte NOS activity that was more potent when obtained from SHR. It is proposed that the increase in HHF, a novel form of NOS inhibitor that is elevated in SHR, may be involved in the rise in arterial pressure.

Animals↗
PubMed1996

Elevated endogenous nitric oxide synthase inhibitor in schizophrenic plasma may reflect abnormalities in brain nitric oxide production.

Cellular origins of methylarginines are not precisely known but the presence of free methyl and dimethylarginines in the brain were reported. We have investigated the circulating concentrations of asymmetrical dimethylarginine NG,NG-dimethylarginine (ADMA), NG,NG-dimethylarginine (SDMA), nitrate and nitrite levels in drug naive first episode schizophrenic patients and matched control subjects. Three of those patients were treated with neurolepties for 3 months. Plasma ADMA levels increased significantly but nitrate levels were significantly low compared to control subjects. Drug treatment apparently lowered ADMA levels and increased nitrate levels in plasma. Methylation of arginine to methylarginines may have an important role in regulating signal transduction through the nitric oxide system in the brain, and suggest novel therapeutic targets.

Adult↗
PubMed1996

Arginine is not responsible for the activation of nitric oxide synthase by garlic.

Garlic (Allium sativum L., Liliaceae) has had an important dietary and medicinal role for centuries. Its chemical constituents have beneficial effects on cardiovascular risk factors and other medicinal effects in the body. Several components of garlic are known but the individual compounds responsible for its divergent properties have yet to be established. There is a link between garlic and the L-arginine-nitric oxide pathway. Amino acid analysis of garlic powder demonstrates that it is a rich source of arginine, the precursor for nitric oxide. However, neither arginine nor alliin-derived products were found to be responsible for the activation of nitric oxide synthase by garlic in cell-free homogenates. Heat treatment of garlic preserved its capacity for enzyme activation.

Amino Acids↗