Search PubMed⌕ Search

Biomedical subjects

A Chakrabarti

Publications and source records attributed to A Chakrabarti.

At least 109 records · Page 6Linked to original sources
PubMed1997

Fine-needle aspiration biopsy in fungal infections.

To evaluate the role of fine-needle aspiration biopsy (FNAB) in diagnosis of fungal infections, a retrospective analysis of 26 cases of fungal infection is described. The spectrum of various fungi encountered on cytologic microscopy of aspirated material and fungal culture was as follows: Aspergillus sp (16 cases), Cryptococcus neoformans (six cases), Mucorales (one case), Candida sp (one case), Phialophora parasiticus (one case), Sporothrix schenkii and Cladosporium sp (the last two isolated from a single case). In majority (71%) of cases, fungal infection was not clinically suspected but was picked up on cytologic material in all the cases. An accurate diagnosis based on morphology could be made in 21 cases (80%). Predisposing factor was found in three patients, two of them had diabetes mellitus and one was on immunosuppression. HIV serology was negative in seven cases tested. Commonest tissue reaction (75%) was foreign body giant cells with foamy macrophages and variable amount of necrosis. Although FNAB is helpful in the rapid diagnosis of fungal infections, culture is essential for more accurate identification.

Adolescent↗
PubMed1997

Interaction of class I human leukocyte antigen (HLA-I) molecules with insulin receptors and its effect on the insulin-signaling cascade.

Insulin receptor (IR) and class I major histocompatibility complex molecules associate with one another in cell membranes, but the functional consequences of this association are not defined. We found that IR and human class I molecules (HLA-I) associate in liposome membranes and that the affinity of IR for insulin and its tyrosine kinase activity increase as the HLA:IR ratio increases over the range 1:1 to 20:1. The same relationship between HLA:IR and IR function was found in a series of B-LCL cell lines. The association of HLA-I and IR depends upon the presence of free HLA heavy chains. All of the effects noted were reduced or abrogated if liposomes or cells were incubated with excess HLA-I light chain, beta2-microglobulin. Increasing HLA:IR also enhanced phosphorylation of insulin receptor substrate-1 and the activation of phosphoinositide 3-kinase. HLA-I molecules themselves were phosphorylated on tyrosine and associated with phosphoinositide 3-kinase when B-LCL were stimulated with insulin.

Adenosine Triphosphate↗
PubMed1997

Primary cutaneous zygomycosis due to Saksenaea vasiformis and Apophysomyces elegans.

We report three cases of primary cutaneous zygomycosis due to either Saksenaea vasiformis (two patients) or Apophysomyces elegans (one patient). Extensive surgical debridement helped two patients recover from their infections. The underlying disease in the one patient who died was diabetes mellitus. We reviewed the literature on primary cutaneous zygomycosis and found that S. vasiformis and A. elegans were the etiologic agents in 16 and 13 earlier cases, respectively.

Adult↗
PubMed1997

Craniofacial zygomycosis caused by Apophysomyces elegans.

A fatal case of craniofacial zygomycosis caused by Apophysomyces elegans in a 52-year-old man was diagnosed by the presence of broad aseptate, branched hyaline hyphae in tissue from paranasal sinuses and surrounding areas, and isolation of the fungus from the same tissue. The patient suffered from idiopathic myelofibrosis as underlying disease, he was thrombocytopenic and was mildly hyperglycaemic. The infection represents the second case of craniofacial zygomycosis due to A. elegans.

Blood Vessels↗
PubMed1997

A comparative study of aminophylline- and acepifylline-induced seizures and death in the chemoconvulsion model in rats.

The convulsive, pro-convulsive and lethal effects of two theophylline-containing bronchodilating agents, aminophylline and acepifylline, have been evaluated in rats. Aminophylline (theophylline ethylenediamine) caused seizures and death in a dose-dependent manner; an intraperitoneal dose of 250 mg kg-1 caused seizures and death in all rats. Intraperitoneal doses of acepifylline (theophylline ethanoate of piperazine) up to 1000 mg kg-1, however, did not cause seizure or death. Further, pre-treatment of the rats by intraperitoneal administration of a subconvulsive dose (100 mg kg-1) of aminophylline caused a significant decrease in CD50 and LD50 values for pentylenetetrazole and a significant increase in the number of positive responders (i.e. rats with a pentylenetetrazole-induced seizure score of 3 or more on a seizure scale ranging from 0 to 6) and death rate compared with those obtained for rats pre-treated with an equivalent intraperitoneal dose (140 mg kg-1) of acepifylline ('equivalent dose' referred to here denotes the theophylline content of the two preparations). The study has established the neurosafety profile of acepifylline and documents a safer alternative to aminophylline for use in asthmatics suffering from concomitant epilepsy or other seizure-prone neurological defects.

Aminophylline↗
PubMed1997

Isolation of Cryptococcus neoformans var. gattii from Eucalyptus camaldulensis in India.

Cryptococcus neoformans var. gattii has an ecological association with five Eucalyptus species: E. blakelyi, E. camaldulensis, E. gomphocephala, E. rudis, and E. tereticornis. After human infections due to C. neoformans var. gattii were diagnosed in the states of Punjab, Himachal Pradesh, and Karnataka, India, a study was undertaken to investigate the association of C. neoformans var. gattii with Indian eucalypts, especially in the state of Punjab. A total of 696 specimens collected from E. camaldulensis, E. citriodora and E. tereticornis (hybrid) trees were examined for the presence of C. neoformans var. gattii. Flowers from two trees of E. camaldulensis in the Chak Sarkar forest and one from the village of Periana near the Ferozepur area yielded five isolates of C. neoformans var. gattii. The origin of the trees could be traced to Australia, thus providing evidence that the distribution of E. camaldulensis correlated with the distribution of human cryptococcosis cases caused by C. neoformans var. gattii in northern India.

Animals↗
PubMed1997

Anxiogenic action of caffeine: an experimental study in rats.

The anxiogenic action of caffeine (10, 25 and 50 mg/kg, i.p.) was investigated in rats and compared with that of yohimbine (2 mg/kg, i.p.). The experimental methods used were the open-field, elevated plus-maze, social interaction and novelty-suppressed feeding latency tests. Caffeine produced a dose-related profile of behavioural changes, which were qualitatively similar to those induced by yohimbine and which indicate an anxiogenic activity in rodents. Thus, both the drugs reduced ambulation and rears, and increased immobility and defaecation in the open-field test. They decreased the number of entries and time spent on the open arms of the elevated-plus maze, reduced social interaction in paired rats and increased the feeding latency in an unfamiliar environment in 48-h food-deprived rats. Lorazepam, a well known benzodiazepine anxiolytic agent, attenuated the anxiogenic effects of caffeine and yohimbine. Subchronic administration of caffeine (50 mg/kg, i.p.) for 21 days, in different groups of animals, induced a significant degree of tolerance in the elevated plus-maze test, which was statistically significant after 14 and 21 days' treatment. Yohimbine, however, did not induce similar tolerance. When caffeine (50 mg/kg, i.p.) was withdrawn after 21 days' administration, to a separate group of rats, significant withdrawal anxiety was observed 48 h later as noted in the elevated plus-maze test. The investigations support clinical evidence of caffeine-induced anxiety, tolerance to anxiety on continued use, and withdrawal anxiety in chronic caffeine-containing beverage users.

Animals↗
PubMed1997

Atypical post-kala-azar dermal leishmaniasis resembling histoid leprosy.

An adult male with atypical lesions of post-kala-azar dermal leishmaniasis (PKDL) is described. He had extensive ulcerated noduloplaque lesions on his hands, feet and genitalia. He had been diagnosed and treated for leprosy in the past. He came from an area endemic for kala-azar and leprosy and had a previous history of kala-azar. There was an abundance of Leishman Donovan bodies in slitskin smears and in histopathology sections. There was a good therapeutic response to sodium stibogluconate. An ulcerative variant of PKDL has been described but is extremely rare. Extensive lesions with ulceration have not been described before to the best of our knowledge. The epidemiological significance of the case is discussed.

Adult↗
PubMed1997

Effect of Trasina, an Ayurvedic herbal formulation, on pancreatic islet superoxide dismutase activity in hyperglycaemic rats.

Diabetes mellitus was induced in male CF strain rats by streptozotocin (STZ) and hyperglycaemia and superoxide dismutase (SOD) activity of pancreatic islet cells was assessed on days 7, 14, 21 and 28. STZ induced significant hyperglycaemia and a concomitant decrease in islet cell SOD activity. Transina (TR), an Ayurvedic herbal formulation comprising of Withania somnifera, Tinospora cordifolia, Eclipta alba, Ocimum sanctum, Picrorrhiza kurroa and shilajit, had little per se effect on blood sugar concentrations and islet SOD activity in euglycaemic rats, in the doses of 100 and 200 mg/kg, p.o. administered once daily for 28 days. However, these doses of TR induced a dose- related decrease in STZ hyperglycaemia and attenuation of STZ induced decrease in islet SOD activity. The results indicate that the earlier reported anti-hyperglycaemic effect of TR may be due to pancreatic islet free radical scavenging activity, the hyperglycaemic activity of STZ being the consequence of decrease in islet SOD activity leading to the accumulation of degenerative oxidative free radicals in islet beta-cells.

Animals↗
PubMed1997

Does candiduria predict candidaemia?

Isolation of Candida from blood is the gold standard for the diagnosis of candidaemia, but because of rather low sensitivity and difficulty in collection of large amounts of blood from children, alternative methods are required. We evaluated the reliability of candiduria as an indicator of systemic candidosis. Blood and suprapubic sample of urine were cultured on the same day from 91 children of paediatric intensive care unit who were clinically suspected to have disseminated candidosis. Candida was isolated from blood in 41.8 per cent patients, from urine in 50.5 per cent patients and both from blood and urine in 27.5 per cent patients. C tropicalis was the commonest yeast isolated from blood (55.3%) and urine (58.7%). The sensitivity and specificity of urine culture for predicting candidaemia were 65.8 and 60.4 per cent respectively, positive predictive value was 54.3 per cent and negative predictive value 71.1 per cent. Urine microscopy had comparable sensitivity (52.6%), specificity (75.5%), positive (60.6%) and negative (70.0%) predictive values. Therefore, candiduria is not a reliable indicator of candidaemia. However, the isolation of non-albicans Candida species from urine was better indicator for candidaemia compared to isolation of C. albicans as 59.5 per cent patients with non-albicans Candida species in urine had candidaemia compared to 33.3 per cent with C. albicans.

Candida↗
PubMed1996

Structural alterations of horseradish peroxidase in the presence of low concentrations of guanidinium chloride.

The presence of very low concentrations of guanidinium chloride (GdmCl) alters the tertiary structure of the monomeric heme-containing enzyme, horseradish peroxidase (HRP). The change in tertiary structure of the protein was reflected in the mean fluorescence lifetime of its single tryptophan residue, which increased from 2.3 +/- 0.1 ns in the native enzyme to 2.7 +/- 0.2 ns in the presence of 100 mM GdmCl. More convincing evidence in support of such alterations came from quenching study of tryptophan fluorescence using the most widely used quencher, acrylamide. It revealed significant differences between the Stern-Volmer quenching constants observed in the absence and in the presence of GdmCl concentrations below 100 mM. The fluorescence emission maximum of 6-propionyl-2-(dimethylamino)naphthalene (PRODAN), used as an extrinsic fluorophore to probe any changes in the tertiary structure of the enzyme, was blue-shifted from 522 nm in aqueous buffer to 509 nm in the presence of 27 microM native HRP. However, this emission maximum appeared at 519 nm when the PRODAN was incorporated in HRP previously incubated with 100 mM GdmCl. The fluorescence lifetime of PRODAN incorporated in HRP was also different from that of PRODAN in buffer, but much more so in absence of GdmCl than in its presence. Taken together, these results indicate partial unfolding of HRP leading to a conformation with native-like secondary structure and unaltered enzymatic activity, in presence of millimolar concentrations of GdmCl.

Circular Dichroism↗
PubMed1996

Fluorescence of spectrin-bound prodan.

A large blue-shift (delta lambda max = 87 nm) in the fluorescence emission maximum and 2-fold enhancement in the emission intensity of PRODAN in the presence of 1.5 microM dimeric spectrin from the same aqueous buffer was observed. Binding of PRODAN to spectrin was estimated from the concentration-dependent change in the ratio of two fluorescence intensities, I520nm for the unbound and I430nm corresponding to the spectrin-bound PRODAN. PRODAN binds to spectrin with a higher affinity (Kapp = 2 X 10(6)M-1) than those reported for BSA and tubulin (Kapp = 1 X 10(5)M-1 for BSA and 5 X 10(4)M-1 for tubulin). This is the first report of PRODAN binding at such a low protein concentration.

2-Naphthylamine↗
PubMed1996

Anxiolytic activity of intraventricularly administered atrial natriuretic peptide in the rat.

Rat atrial natriuretic peptide (ANP) was investigated for putative anxiolytic activity in rats, following intracerebroventricular (ICV) administration. ANP in doses of 200 and 500 ng/rat induced significant anxiolysis, comparable with that of lorazepam (0.5 mg/kg, i.p.) in a variety of anxiety models (open-field, elevated plus-maze, social interaction, and novelty-induced feeding suppression tests). Isatin, an endogenous anxiogenic indole, shown to be an antagonist of ANP in vitro, significantly inhibited the anxiolytic effect of ANP in the elevated plus-maze test in subanxiogenic doses. The anxiolytic action of ANP was unaffected by flumazenil, a benzodiazepine receptor antagonist. Conversely, the anxiolytic action of lorazepam was antagonized by flumazenil but not by isatin. The data indicate that ANP may function as an endogenous anxiomodulator, which may act in conjunction with isatin independently of benzodiazepine receptors. These results strengthen the evidence for links between physiological systems involved in anxiety and those in natriuresis.

Animals↗