Search PubMed⌕ Search

Biomedical subjects

K Gulati

Publications and source records attributed to K Gulati.

At least 19 recordsLinked to original sources

Role of nutrition in toxic injury.

The importance of nutrition in protecting the living organism against the potentially lethal effects of reactive oxygen species and toxic environmental chemicals has recently been realized. This new perspective has prompted re-evaluation of the food constituents of human diet from the point of view of their nutritional adequacy, deficiency and toxicity. The biological antioxidant defense system is an integrated array of enzymes, antioxidants and free radical scavengers. These include glutathione reductase, glutathione-s-transferase, glutathione peroxidase, phospholipid hydroperoxide glutathione peroxidase, superoxide dismutase (SOD) and catalase, together with the antioxidant vitamins C, E and A. The individual components of this system get utilized in various physiological process and for chemoprotection and therefore require replenishment from the diet. Other components of the diet like carbohydrates, proteins and lipids are important for maintaining the levels of various enzymes required in body's defense system providing protection against carcinogens. However, the emerging newer concepts focus on the role of trace elements and other dietary components in antioxidant defense and detoxification mechanisms. Trace elements like Iron, zinc magnesium, selenium, copper, and manganese are some of the elements involved in antioxidant defense mechanisms. Inadequate intake of these nutrients has been associated with ischemic heart disease, arthritis, stroke and cancer, where pathogenic role of free radicals is suggested. Further the importance of diet in the prevention of chemical induced toxicity can not be undetermined. Recent reports on the role of bioflavonoids as antioxidents and their potential use to reduce the risks of coronary heart disease and cancer in human beings have opened a new arena for future research. Induction of the cytochrome P450 isoenzymes by food pyrolysis, mutagens, alcohol and fasting, on the other hand is reported to contribute to chemical toxicity and carcinogenecity. Certain chemicals moieties in the food are mutagenic and carcinogenic.

Animals↗

Biochemical and histopathological changes in respiratory system of rats following exposure to diesel exhaust.

Effect of exposure to diesel exhaust (DE) for different durations was evaluated using histopathological and biochemical parameters in respiratory system of the rats. Animals were exposed to 1 part DE diluted with 5 parts of clean air in a simulation chamber for 15 min/day for 1, 7, 14 and 21 days. After completion of various exposures, biochemical parameters including elastase inhibitory capacity (EIC) and protein content of the bronchial airway lavage (BAL) and histopathological changes along with lung/body weight ratio were assessed. The elastase inhibitory capacity (an index of the protection against destruction of elastin, a lung connective tissue) was maximum at 1 week indicating thereby that the body renders protection against injury by increasing EIC levels in the initial phase. However, protein content in the BALF increased after 1 week and reached maximum at 2 weeks. Histopathological changes followed similar time course of pattern with accumulation of macrophages and protein exudation. Prolonged exposure up to 3 weeks, however was accompanied by chronic inflammatory changes and thickening of alveolar septa and blood vessels. Changes in lung/body weight ratio and suspended particulate matter (SPM) deposited on filters (simulation chamber) correlated well with EIC, protein content in BALF and histopathological changes. The biochemical findings accompanied with chronic structural changes in the lungs of rats following exposure to DE could be relevant to the clinical observation of increased incidence of chronic lung diseases after continued DE exposure.

Air Pollutants↗

Tuberculosis in childhood nephrotic syndrome in India.

We studied the prevalence, clinical features, and impact of tuberculosis (TB) on children with nephrotic syndrome (NS). Of the 300 children with NS, 28 (9.3%) were diagnosed as having TB. This occurred following the initiation of immunosuppressive therapy in 27 children, and in 1 child it preceded the onset of NS. Pulmonary involvement was the commonest (22/28), followed by tubercular lymphadenitis (2/28), meningitis (2/28), and occult TB (2/28). Of the various diagnostic criteria, history of previous cough, fever, or exposure to a case of TB (23/28) and chest skiagram (21/28) were the most useful. The occurrence of TB did not induce a relapse or affect the subsequent response to steroid therapy (as is often seen with other infections) or have a deleterious effect on renal function. Patients who received higher doses of steroids (frequent relapsers, steroid dependent, initial non-responders, and subsequent non-responders) had a significantly higher prevalence of TB (19/148) than those who received lower doses (infrequent relapsers 8/151) (P = 0.04). We thus found TB to be an important complication of children with NS in our country. The conventional diagnostic tests, such as Mantoux and acid-fast bacilli isolation, are often unhelpful in these children, and a high index of suspicion is required, especially in children who require frequent courses of steroid therapy.

Adolescent↗

Cadmium induced nephrotoxicity in rats.

Onset of hypertension and nephropathy after 1,2, and 4 weeks of exposure to cadmium chloride (1 mg/kg, ip) was studied in rats by measuring changes in blood pressure and renal function (urinary output, electrolytes, serum creatinine, inulin clearance and Na+K+ ATPase). Significant decrease in body weight and rise in blood pressure were observed as early as one week of exposure while microalbuminuria was detected in 50% of the animals after 2 weeks. Na+K+ ATPase, a renal tubular enzyme, was depressed after 1 week with maximum lowering occurring after 4 weeks. There were no detectable changes in fluid intake, urine output, electrolytes, inulin clearance and serum creatinine even after 4 weeks. It is concluded that hypertension and tubular lesion set in earlier than glomerulopathy as indicated by microalbuminuria and the latter could be the consequence of rise in blood pressure.

Animals↗

Involvement of renin-angiotensin system in hypertensive effect of cadmium in rats.

Role of renin-angiotensin system in hypertension induced by cadmium chloride (CdCl2) in rats has been investigated. Intravenous administration of CdCl (1 mg/kg) produced a biphasic response i.e. a transient fall followed by a marked and consistent rise in blood pressure. The peak hypertensive effect was accompanied by raised PRA levels. Pretreatment with captopril (1 mg/kg, i.v.) losartan (1 mg/kg, i.v.) or captopril + losartan attenuated the pressor response to Cd by 62%, 42% and 100% respectively in separate groups. Central administration of Cd (10 micrograms/rat, i.c.v.) showed a biphasic response similar to that observed after i.v. route. However, it was not accompanied by raised PRA levels. Prior treatment with losartan (10 micrograms/rat, i.c.v.) completely abolished the pressor response to Cd (i.c.v.) whereas it was not affected significantly by captopril (10 micrograms/rat, i.c.v.). On the other hand, centrally administered losartan only partially reduced the pressor response to i.v. Cd. The results are discussed in light of a differential involvement of central vs peripheral renin-angiotensin system in the hypertensive effect of Cd.

Animals↗

Effect of short and long-term exposure to diesel exhaust on sensitivity of guinea pig tracheal preparation to histamine.

Single exposure, to diesel exhaust (1 part exhaust diluted by 5 parts of clean air) reduced EC50 of histamine indicating hyperresponsiveness of the receptors in trachea of exposed guinea pigs. In contrast, following repeated exposure for 7, 14 or 21 days (15 min/day), EC50 was progressively increased indicating the possibility of down-regulated histamine receptors. Further, simultaneous significant increase in histamine levels (bioassayed on guinea pig ileum) in bronchial airway lavage fluid supports the aforementioned hypothesis. The change in lung/body weight ratio and suspended particulate matter deposited on filters followed the same temporal pattern as EC50. The findings are suggestive of differential effects of diesel exhaust on airway depending upon the duration of exposure.

Air Pollutants↗

Angiotensin II--receptor subtypes characterization and pathophysiological implications.

In the past decade there have been considerable advances in basic knowledge of the renin-angiotensin system (RAS). The most important new development has been the appreciation of a tissue based RAS that can be independently regulated from the renal and vascular RAS. Greater insight into the mechanism by which angiotension-II (AII) exerts its action has been achieved through the study of molecular biology and pharmacological characterization of multiple receptor subtypes. This review summarises the features and distribution of several binding subtypes that may mediate the diverse functions of AII. Of these AT1 subtype is the most well known receptor which preferentially binds AII and AIII. The AT1 receptor site appears to mediate the classic angiotensin responses concerned with the body water balance and the maintenance of blood pressure. Less is known about the AT2 sites which also bind AII and AIII and may play a role in vascular growth. Recently, an AT3 has been discovered in cultured neuroblastoma cells and an AT4 site which preferentially binds AIV. It has been implicated in memory aquisition and retrieval and in the regulation of blood flow. Another important aspect covered is the primary and secondary messengers involved during the signal transduction after the binding of AII with receptors. A stress has also been given on the regulation of density and affinity of AII receptors by various physiological parametres as they affect the responses of RAS. Autoregulation by RAS, salt intake, development and aging and some of the hormones are important variables which could affect the AII receptors. Interactions of AII with various neuroeffector transmission involved in the regulation of water-electrolyte balance and BP regulation play an important role in the maintenance of the homeostasis. AII has been suggested to increase the NAergic transmission by enhancing synthesis, release, inhibiting reuptake by the presynaptic nerve terminals as well as enhancing cell responsiveness to the transmitter. The finding of existence of AII receptors in vagal afferent nerve terminals suggests that its baroreflex inhibitory effect is mediated by inhibiting neurotransmitter release at NTS in the baroreflex arc. Moreover, AII acts on the central receptors to stimulate AVP and ACTH secretion, drinking and peripherally increase synthesis and secretion of aldosterone. Interactions of RAS with kallikrein-kinin system and prostaglandins strongly support the existence of a balance between renal depressor and pressor substances. AII is now considered a growth promotor in cardiovascular tissues and the resultant vascular hypertrophy could contribute in the maintenance of hypertension. AII also plays a role in the kidney, not only as a regulator of hemodynamics but also in the structural changes occurring in a variety of renal disorders. In addition to the more well studied functions of RAS in RVH the review also highlights the potential contribution by the RAS to other clinically relevant syndromes such as aortoarterities induced RVH, hyperaldosteronism, heavy metal induced cardiovascular effects, diabetes mellitus and thyroid dysfunction. Although the receptor subtypes involved in these pathological states have not been definitely identified, research efforts in this direction are ongoing.

Animals↗

Effects of intrahypothalamic morphine and its interactions with oxytocin and vasopressin during food intake in rats.

The effects of intra-hypothalamic microinjections of morphine (MOR) into the ventromedial (VMH) and lateral (LH) nucleus and its interactions with oxytocin (OXY) and vasopressin (AVP) were evaluated during food intake FI) in rats. Acute MOR clearly enhanced FI during the dark phase (6-24 h) of the diurnal cycle, while no appreciable changes in the light phase (0-6 h) FI was seen after intra-VMH or LH injections. Long term MOR administration into both VMH and LH attenuated the enhancements in FI seen after acute MOR during the dark phase, while FI was enhanced during the light phase. Pretreatment with OXY or AVP clearly antagonized such tolerance or reverse tolerance/sensitization development to the orexic effect of MOR. These results are discussed in the light of complex peptidergic interactions in the hypothalamus during ingestive behavior.

Analysis of Variance↗

Differential effects of intrahypothalamic administration of opioids on food intake in naive and tolerant rats.

We investigated the effects of intrahypothalamic administrations of the opioid agonists morphine (MOR) and ketocyclazocine (KCZ) and antagonists naltrexone (NALTX) and Mr2266 on food intake (FI) during light and dark phases of the diurnal cycle, after acute or chronic administration in rats. Acute intralateral hypothalamic (LH) administration of MOR or KCZ (1 microgram/rat) enhanced FI during dark and light phases, respectively, whereas intraventromedial hypothalamic (VMH) injections resulted in moderate hyperphagia during dark phases by both mu and kappa agonists. The receptor specificity was evident from blockade of the responses to MOR or KCZ by the respective antagonists NALTX and Mr2266. After repeated administrations of MOR and KCZ, FI responses to the test dose of these agonists injected in LH were modulated in opposite directions. However, the adaptative changes in FI after intra-VMH injection of KCZ were similar to those seen with MOR. These results are discussed in light of a differential opioid receptor involvement and their possible functional interactions within the hypothalamus during food intake.

Animals↗

The amygdaloid complex, corticotropin releasing factor and stress-induced gastric ulcerogenesis in rats.

The amygdaloid complex and corticotropin releasing factor (CRF) are both important in stress reactions and we thus evaluated the effects of intra-amygdalar CRF on stress ulceration in rats. Bilateral micro-applications of CRF (0.05, 0.5 or 5.0 micrograms) into the central amygdala (CEA) attenuated cold restraint-induced gastric mucosal lesions in a dose-related manner. Similar gastric cytoprotective effects were seen with intra-CEA noradrenaline (NA; 3.0 micrograms), whereas the NA neurotoxin, DSP-4 (25 micrograms), or the beta-adrenoceptor antagonist, propranolol (1 microgram), aggravated stress ulcer pathology. Intra-CEA pretreatment with DSP-4 or propranolol clearly reversed the ulceroprotective effects of CRF during stress. These results indicate that the CEA is a neural substrate for CRF effects, and CRF-NA interactions in this limbic area are crucial for the regulation of stress ulcerogenesis.

Amygdala↗

Germline rearrangement of MCC and APC detected by pulsed field gel electrophoresis and fluorescent in situ hybridization.

Pulsed field gel electrophoresis was carried out on lymphocyte DNA obtained from ten patients with the inherited premalignant condition adenomatous polyposis coli and a similar number of control samples to search for large scale molecular rearrangements in the vicinity of the APC locus. DNA from one patient showed a rearranged pattern which was interpreted as evidence for an inversion of approximately 150 kb, changing the transcriptional orientation of the neighbouring MCC gene and bringing it closer to APC. Such an interpretation was supported by fluorescent in situ hybridization data.

Adenomatous Polyposis Coli↗

Role of kappa opioid receptors during stress responsiveness in rats.

Effects of kappa opioid agonist, ketocyclazocine (KCZ) and its antagonist, M(r) 2266, were evaluated on some stress responses in rats. KCZ (1 or 10 mg/kg, ip) dose-dependently attenuated cold restraint stress (CRS)-induced gastric ulcer formation. Similar gastric cytoprotection was also seen with KCZ (1 or 10 micrograms/rat, icv). Pretreatment of rats with M(r) 2266 (0.3 mg/kg, ip) clearly antagonized the ulceroprotective effects of both ip and icv KCZ. KCZ effects on the gastric mucosa during CRS were also reduced by naltrexone (5 mg/kg, ip) pretreatment. KCZ (1 or 10 mg/kg, ip) also attenuated the plasma corticosterone response to CRS and these effects were blocked by M(r) 2266 (0.3 mg/kg) pretreatment. These results indicate kappa opioid receptor involvement during stress reactions and also suggest possible opioidergic interactions during CRS.

Animals↗

A gene from human chromosome region 3p21 with reduced expression in small cell lung cancer.

A combination of cytogenetic and molecular studies has implicated the p21 region of human chromosome 3 as the probable site of a gene the loss of which contributes to the development of small cell lung cancer. We report here the isolation of a gene from this region which is expressed in normal lung tissue and in cell lines derived from a number of different types of tumor, but the expression of which in small cell lung cancer cell lines is undetectable by RNA blot analysis. Although the more sensitive polymerase chain reaction did detect transcripts, a novel quantitative polymerase chain reaction assay showed that their concentration in small cell lung cancer cell lines is less than 3% of that in normal lung.

Carcinoma, Small Cell↗

Effects of acute and chronic ketocyclazocine and its modulation by oxytocin or vasopressin on food intake in rats.

The effects of acute and chronic ketocyclazocine (KCZ, a kappa receptor agonist) and its interactions with oxytocin (OXY) or vasopressin (AVP) were investigated on food intake in free-fed rats. Acute treatment with KCZ (1 mg/kg) produced a generalized hyperphagia during the light phase (0-6 h) without influencing dark phase (6-24 h) food intake. On chronic administration, tolerance developed to hyperphagic effect during light phase, whereas an enhancement in the food intake was seen during dark phase. OXY or AVP (both at 10 micrograms/kg) per se, did not affect the food intake response during either the light or the dark phase, after acute as well as chronic treatment. In the interaction studies, acute AVP or OXY attenuated the hyperphagia of KCZ during the light phase. On chronic treatment, both AVP and OXY blocked (a) the tolerance, and (b) the "reverse tolerance" to the food intake response to KCZ during light and dark phases, respectively. These results are discussed in light of complex opioid-OXY/AVP interactions during food intake in rats.

Animals↗

Effects of acute or chronic opioid agonists and their modulation by diurnal rhythmicity and satiety states on food intake in rats.

The effects of acute or chronic treatment with mu and k opioid agonists were investigated on food intake during light (0-6 hr) and dark (6-24 hr) phases in free fed and fasted rats. In free fed rats, morphine (MOR, 5 mg/kg, ip), a mu-agonist, induced a hyperphagic response during both light and dark phases, whereas ketocyclazocine (KCZ, 1 mg/kg, ip), a k-agonist, enhanced food intake only during the light phase. Chronic MOR (x 7 days) produced a further enhancement of hyperphagia in the light phase and attenuated the dark phase response. Chronic KCZ, however, had opposite effects, i.e. tolerance to light phase hyperphagia and an enhancement in the dark phase response. In fasted rats, neither MOR nor KCZ appreciably enhanced food intake after acute administration but chronic treatment potentiated the acute opioid effects. These results are discussed in light of the role of diurnal rhythmicity, satiety states and receptor (mu and k) specificity/interactions in the opioidergic regulation of food intake.

Animals↗