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Biomedical subjects

S K Mitra

Publications and source records attributed to S K Mitra.

At least 19 recordsLinked to original sources
PubMed1992

Multiple cytomegalovirus-related intestinal perforations in patients with acquired immunodeficiency syndrome. Report of two cases and review of the literature.

We present two cases of patients with acquired immunodeficiency syndrome who, in the course of their disease, suffered multiple intestinal perforations that were directly related to cytomegalovirus infection. Biopsy and surgical specimens and autopsy findings in both cases revealed extensive lesions of gastroenteritis; the gastroenteritis was characterized by randomly distributed deep ulcers, resulting in multiple perforations. The main characteristic histopathologic finding was the association of intestinal lesions with a severe form of cytomegalovirus-related occlusive vasculitis. This report provides evidence that supports the contention that cytomegalovirus is the primary causal agent of gastrointestinal lesions affecting immunocompromised patients.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Anxiogenic activity of quinine--an experimental study in rodents.

Quinine, a cinchona alkaloid, was investigated for putative anxiogenic activity in view of clinical reports suggesting that it induces anxiety and apprehension following its use in malaria. The experimental paradigms chosen to elucidate anxiogenic activity have been shown to stand the tests of reliability and validity. Yohimbine, which has been shown to induce anxiety both in animals and in man, was used for comparison. Quinine was found to elicit a complex behavioural profile of activity ranging from overt central stimulation to marked central depression on dose increment. The doses 10 and 20 mg/kg, ip, of quinine chosen to investigate anxiogenic activity were comparable to those induced by 2.5 and 5 mg/kg ip of yohimbine. Quinine induced a dose-related anxiogenic activity in the open-field and elevated plus-maze tests in mice, and the social interaction and thirst conflict tests in rats, similar to effects induced by yohimbine. In addition, both quinine and yohimbine attenuated the effects of diazepam, an anxiolytic agent, in the open-field and thirst conflict tests. The results indicate that quinine exerts significant anxiogenic effect at a particular dose range.

Analysis of Variance↗
PubMed1991

Anxiolytic activity of Panax ginseng roots: an experimental study.

The putative anxiolytic activity of the white and red varieties of ginseng, the root of Panax ginseng, was investigated in rats and mice using a number of experimental paradigms of anxiety and compared with that of diazepam. Pilot studies indicated that single-dose administration of ginseng had little to no acute behavioural effects, hence the two varieties of ginseng were administered orally at two dose levels twice daily for 5 days, while diazepam (1 mg/kg, i.p.) was administered acutely. White and red varieties of ginseng (20 and 50 mg/kg) showed positive results when tested against several paradigms of experimental anxiety. Both were effective in the open-field and elevated plus-maze tests and reduced conflict behaviour in thirsty rats and footshock-induced fighting in paired mice. Ginseng also attenuated pentylenetetrazole-induced decrease in rat brain MAO activity, confirming its anxiolytic activity since this has been proposed to be an endogenous marker for anxiety. The effects induced by white and red ginseng (50 mg/kg x 5 days) were comparable to those induced by diazepam (1 mg/kg).

Aggression↗
PubMed1991

Serotonergic modulation of footshock induced aggression in paired rats.

Footshock induced aggression (FIA) was induced in paired rats and three paradigms of aggressive behaviour were recorded, namely, latency to fight (LF), total period of physical contact (TPP) and cumulative aggression scores (CAS). The effects of increasing or decreasing central serotonergic activity, by using a number of pharmacological agents with well defined effects on rat brain serotonin, were investigated on FIA and on FIA augmented by apomorphine, a dopamine receptor agonist. The results show that centrally administered serotonin, the serotonin precursor, 5-hydroxytryptophan administered with clorgyline, a selective MAO A inhibitor, quipazine, a serotonin receptor agonist, and fluoxetine, a selective inhibitor of neuronal re-uptake of serotonin, attenuated all paradigms of FIA and apomorphine induced potentiation of FIA. On the contrary, the other re-uptake inhibitor used, citalopram, appeared to have a dual effect and decreased LF and CAS, while increasing TPP. The serotonin synthesis inhibitor, p-chlorophenylalanine and the selective serotonin receptor (5-HT2) antagonist, ketanserin, augmented all paradigms of FIA per se and apomorphine induced augmentation of FIA. However, the other serotonin receptor antagonist used, metergoline, which blocks both 5-HT1 and 5-HT2 receptor subtypes, attenuated FIA per se but decreased only CAS in apomorphine induced increase in FIA. The data confirm the inhibitory effect of the central serotonergic system on aggressive behaviour and the inverse relationship existing between it and the central dopaminergic system in the modulation of FIA, as has also been confirmed in earlier biochemical investigations from this laboratory. The data has been discussed in the light of existing knowledge on serotonin receptor subtypes and the presence of modulatory serotonergic heteroreceptors on central dopaminergic neurones.

5-Hydroxytryptophan↗
PubMed1991

Effects of muscarinic receptor agonists and antagonists on response of non-extensor rats to maximal electroshock.

Rats which do not respond consistently to maximal electroshock by exhibiting the classical hindlimb extensor response, are designated as 'flexors', and can serve as a useful experimental model for investigating seizure mechanisms. 20-25% Charles Foster rats exhibit the flexor status and were used in this study. The flexor rats were converted to extensors by acetylcholine (icv), physostigmine (ip) and the selective muscarinic M1 receptor agonists, arecholine (ip) and McN-A-343 (icv). This conversion of flexors to extensors was significantly attenuated by M1 receptor antagonists scopolamine (ip) and pirenzepine (icv). The M2 receptor agonist, carbachol (icv), had no effect in lower doses but induced conversion of flexor rats to the extensor status only in very high doses which may be due to loss of receptor specificity on dose increment. The M2 receptor antagonists, gallamine (icv) and AF-DX 116 (ip), also induced significant conversion of flexors to extensors, which was dependent upon the availability of neuronal acetylcholine since the effects were attenuated following pretreatment with hemicholinium, an inhibitor of acetylcholine synthesis. The results suggest that the central cholinergic system has a facilitatory pro-convulsant effect, mediated through the muscarinic M1 receptors, an action modulated by the M2 receptors.

Acetylcholine↗
PubMed1991

ERCP in the evaluation of choledochal cyst due to anomalous pancreatobiliary junction.

With the application of endoscopic retrograde cholangio pancreatography (ERCP), the association of anomalous pancreatobiliary junction and choledochal cyst is being increasingly recognized. We describe here the ERCP findings in three patients who had this anomaly in association with fusiform (Type I) choledochal cyst. Two of our patients also had evidence of pancreatitis. The importance of ERCP in the preoperative assessment of such patients is highlighted.

Adolescent↗
PubMed1990

Sclerotherapy in extrahepatic portal venous obstruction.

One hundred and twenty two patients who presented with variceal bleeding as a result of extrahepatic portal vein obstruction (EHPO) were entered into the sclerotherapy programme with a mean follow up of 23.69 months (range four to 60 months). Eighteen (14.7%) patients were lost to follow up, three (2.4%) patients underwent surgery, and six (4.9%) patients died. Variceal obliteration was achieved in the remaining 95 patients requiring 5.4 (2.4) sessions of sclerotherapy (range 2-18). Seventeen episodes of upper gastrointestinal bleed occurred in 15 patients during sclerotherapy. Recurrence of oesophageal varices was seen in 15 patients. Ten patients developed bulbous gastric varices after obliteration. Major complications including perforation and strictures were seen more commonly in children. Sclerotherapy was associated with a significant reduction in the bleeding rate (bleeds/month/patient) as compared with the presclerotherapy period (p less than 0.001). Endoscopic sclerotherapy is an effective and safe modality in the prevention of variceal bleeds in patients with extrahepatic portal vein obstruction.

Adolescent↗
PubMed1990

Superadded aspergillosis on carcinoid bronchial adenoma leading to delayed diagnosis.

A review of aspergillosis in neoplastic disease revealed that most cases occur in association with malignant disorders. Amongst solid tumours it is mostly adenocarcinomas which are invaded by the fungus due to necrotic cavity formation. We here record the first reported association of aspergillosis with a benign carcinoid bronchial adenoma which was hidden by the fungal growth with a delay in diagnosis.

Aspergillosis↗
PubMed1979

Relative efficiency of anticodons in reading the valine codons during protein synthesis in vitro.

Using a protein synthesizing in vitro system programmed with MS 2-RNA, the relative efficiency (in the presence of each other) of valine tRNAs with the anticodons U*AC (U* represents 5-oxyacetic acid uridine monophosphate), GAC, and IAC to read the valine codons was investigated. An anticodon which can read all three positions of the codon according to the rules of Watson-Crick base-pairing and the wobble hypothesis is an order of magnitude more efficient than an anticodon which misreads the codon by reading only the first two positions and presumably disregards the third nucleotide of the codon. There are two seeming exceptions to this behavior: the anticodon U*AC reads the codon GUU quite efficiently and IAC is as effective as U*AC in reading the codon GUG. The significance of these exceptions is evaluated with respect to the organization and evolution of the genetic code.

Anticodon↗
PubMed1979

The pathology of noncirrhotic portal fibrosis: a review of 32 autopsy cases.

A wide spectrum of clinical and morphologic changes in 32 autopsy cases of noncirrhotic portal fibrosis have been described. The disease frequently occurs in younger patients with a long history of splenomegaly, usually with a history of hematemesis. Females are affected almost equally as often as males in contrast to cirrhosis. The patients tolerate the bleeding episodes well. Death is usually due to massive hemorrhage. The diagnosis is achieved through a process of exclusion. A critical analysis of hemodynamic data, a splenoportogram, liver function tests (particularly Bromsulphalein retention) and angiographic data is mandatory. Needle biopsy of the liver appears to have limited value in making the diagnosis. The gross anatomic findings vary from a nearly normal liver to gross nodularity, seen particularly on the posteroinferior surface. In some cases these nodules are seen to physically impede the portal blood flow and contribute to portal hypertension. Phlebosclerosis of the smaller radicles of the portal vein and irregular scarring are the outstanding morphologic features of the disease. These changes are usually associated with irregular dilatation of some of the larger intrahepatic branches of the portal vein as well as fibroelastosis with or without occluding or organizing thrombi in both intra- and extrahepatic branches of the portal vein. The changes in hepatic venous radicles are characterized by irregular sclerosis, which seems to contribute significantly toward postsinusoidal block in advanced cases. The probable mode of evolution is discussed.

Adolescent↗
PubMed1979

Chronic oral arsenic intoxication as a possible aetiological factor in idiopathic portal hypertension (non-cirrhotic portal fibrosis) in India.

Estimates were made of the arsenic concentration in liver specimens from nine patients having idiopathic portal hypertension (IP), and in four livers these were found to be significantly higher than those in patients with cirrhosis and in control subjects. The splenovenogram revealed extensive portosystemic collateral circulation. Corrected sinusoidal pressure and blood flow studies showed higher levels in four patients than in normal subjects. Microscopic examination of liver tissues revealed periportal fibrosis. The higher hepatic arsenic levels that were found were due to the inadvertent drinking of water contaminated with arsenic, adulterated opium, and indigenous medicines. A history of opium intake was not forthcoming but two patients had drunk water contaminated with arsenic and two others had taken bhasams (Ayurvedic medicines prepared by repeated oxidation of ores). Though the aetiology of idiopathic portal hypertension is not known, it is possible that arsenic intake may be one of the factors.

Adolescent↗