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Biomedical subjects

A K Roy

Publications and source records attributed to A K Roy.

At least 109 records · Page 6Linked to original sources
PubMed1990

Cysticercal meningoencephalitis.

Meningoencephalitic syndrome can be caused by many infective agents. Over a period of 13 years, 15 of 170 cases of neurocysticercosis (NCC) presented as meningoencephalitis. The basis of diagnosis of NCC was positive subcutaneous nodule histopathology (4), CT scan (9) and autopsy (3) findings. The age of the patients ranged from 7-68 years (mean 32). Fever was encountered in 12, altered sensorium in 7, seizures in 10 and abnormal behaviour in 3 cases. All cases had papilloedema. Focal neurological signs included optic atrophy, lateral rectus palsy, hemiplegia, internuclear ophthalmoplegia and cerebellar ataxia. Cerebrospinal fluid was abnormal in 8 of 13 cases, leading to a suspicion of tuberculous meningitis. Twelve patients improved with therapy. Three cases ended fatally and autopsy confirmed the diagnosis.

Adolescent↗
PubMed1990

Computed tomographic spectrum of neurocysticercosis.

Computed tomography (CT) is a very sensitive modality for the diagnosis of neurocysticercosis. Fifty eight patients were evaluated by plain radiography and CT scans. The initial presentation was as seizure disorder (33), raised intracranial tension (19), meningoencephalitis (5) and psychiatric manifestation (1). Histologically confirmed subcutaneous nodules were seen in 20 cases and ocular cyst in 2 cases. CT scan showed multiple calcification in 8 cases, disc lesions in 30,ring lesions in 3, and a combination of disc and ring lesions in another 13 cases. Low attenuation lesions were seen in 4 cases in combination with disc/disc and ring lesions. All 58 cases had supratentorial lesions while 19 cases had infratentorial lesions in addition. Perifocal or generalised oedema was seen in 33 and 11 cases respectively. The ventricles were compressed in one case, large in 2 cases and normal in the rest. CT scan is valuable in the diagnosis of neurocysticercosis. Its significance is different in the various clinical and radiological groups.

Adolescent↗
PubMed1990

Modifying effects of calcium on aluminum induced toxicity in mammalian tissues in vivo.

Oral administration of calcium, following by aluminium or together with Al, has been found to counteract the toxic effects of the latter metal as observed in histological preparations of liver, brain, kidney, and bone of laboratory albino rats. No such improvement was seen if Ca was administered after Al. The protection afforded by Ca against Al toxicity may be due to the previous occupation by Ca ions of the binding sites of Al ions in the affected organs.

Aluminum↗
PubMed1989

Purification and immunochemical characterization of the cytoplasmic androgen-binding protein of rat liver.

The cytoplasmic androgen-binding (CAB) protein of the male rat liver has been implicated to play a role in the androgen-dependent regulation of alpha 2u-globulin synthesis. The liver of the adult male rat contains about 50 fmol of specific high-affinity androgen-binding activity per milligram of total cytosolic protein. Photoaffinity labeling with [3H]R-1881 followed by SDS-polyacrylamide gel electrophoresis and autoradiography shows that the CAB is a 31-kilodalton protein. By means of DEAE-cellulose chromatography and preparative SDS-polyacrylamide gel electrophoresis, we have purified the CAB protein to electrophoretic homogeneity and have raised polyclonal rabbit antiserum that is monospecific to this protein. In the sucrose density gradient, the antiserum reacted with the androgen-binding component of the male liver cytosol prelabeled with tritiated dihydrotestosterone. Western blot analysis of the liver cytosol showed that the antiserum recognizes only the 31-kDa androgen-binding component. Such immunoblotting also showed that unlike the young adult, the androgen-insensitive states during prepuberty and senescence are associated with a marked reduction in the hepatic concentration of the immunoreactive CAB protein. No immuno-chemical cross-reactivity between CAB and another androgen-binding component of Mr 29K (which is associated with androgen insensitivity during prepuberty and senescence) was observed. The latter finding favors the possibility that 31- and 29-kDa androgen-binding components may have distinct sequence structure.

Aging↗
PubMed1989

A time-course study on effects of aluminium on mitotic cell division in Allium sativum.

Cytotoxic effects of aluminium sulphate on root-tip cells of Allium sativum during a time-course study and during recovery were observed. The endpoints considered were mitotic index and frequencies of aberrant cells and micronuclei induced. Chronic exposure induced mitotic depression and abnormal cells to a degree directly proportional to the concentration used and the period of treatment up to 24 h. A reduction of the early higher level of toxicity was noticed following 48 h of treatment and subsequent recovery in aluminium-free nutrient media in experiments carried out with lower concentrations.

Allium↗
PubMed1989

Phagolysosomal alterations induced by unleaded gasoline in epithelial cells of the proximal convoluted tubules of male rats: effect of dose and treatment duration.

Short-term oral administration of unleaded gasoline to male rats reproduces the accumulation of phagolysosomes (hyaline droplets) in epithelial cells of the renal proximal convoluted tubules (PCT) observed following long-term inhalation of wholly volatilized gasoline. Phagolysosomes are partially composed of alpha 2u-globulin, a low-molecular-weight protein, unique to male rats. In this study, dose-dependent and chronologic alterations of phagolysosomes caused by gasoline were observed by transmission electron microscopy. Exposure to commercially available unleaded gasoline (0.4-2.0 ml/kg, po, once daily, 9 d) increased the number and size of phagolysosomes in epithelial cells of the PCT in male rat kidney. However, administration of 0.04 ml gasoline/kg or less was ineffective in inducing phagolysosomal accumulation. Subcellular analysis revealed that many of the phagolysosomes observed in treated rats (doses greater than 0.4 ml/kg) were angular and had cross-sectional diameters varying from 0.5 to 9 microns; in controls the majority of phagolysosomes were round and their diameter varied from 0.5 to 2.5 microns. Treatment of male rats with gasoline (2.0 ml/kg body weight, po, 1-9 d) caused a progressive increase in the number and size of phagolysosomes in PCT epithelial cells dependent on treatment duration. Alterations in phagolysosomal morphology and quantity occurred within 20 h following a single dose of gasoline, emphasizing that the process of phagolysosome accumulation is a dynamic phenomenon. Many of the enlarged phagolysosomes contained a condensed, crystalline core of greater electron density than the surrounding matrix. Furthermore, the rapid increase in abnormal, condensed contents in the phagolysosomes may indicate that a derangement of renal protein catabolism is the primary mechanism by which fuel hydrocarbons cause hyaline droplet nephropathy in male rats.

Animals↗
PubMed1989

32P-postlabeling analysis of 1-nitropyrene-DNA adducts in female Sprague-Dawley rats.

The 32P-postlabeling technique was used to qualitatively establish the pattern of DNA adduct formation in mammary tissue and liver following administration of 1-nitropyrene to female Sprague-Dawley rats. 1-Nitropyrene (100 mg/kg b.w.) was administered by gavage in trioctanoin and the rats were sacrificed 24 h later. DNA was isolated from mammary fat pads and liver, enzymatically hydrolyzed to deoxyribonucleoside-3'-monophosphates and then converted to [5'-32P]3',5'-bisphosphates. The polyethyleneimine-cellulose (PEI-cellulose) TLC 32P-fingerprints revealed the presence of multiple putative adducts in the mammary fat pads and in the livers. To investigate the role of nitroreduction in the formation of these adducts, calf thymus DNA was incubated with [3H]1-nitropyrene in vitro in the presence of xanthine oxidase. The DNA was isolated and analyzed by the 32P-postlabeling technique. A major adduct spot was detected and confirmed as N-(deoxyguanosin-8-yl)-1-aminopyrene. This adduct cochromatographed with a minor in vivo adduct of DNA obtained from mammary fat pads and livers. However, the major adducts detected in vivo did not appear to originate from simple nitroreduction of 1-nitropyrene. The results of this study suggest that other metabolic pathways, such as ring oxidation, or ring oxidation followed by nitroreduction, may be responsible for the putative 1-nitropyrene-DNA adducts observed in mammary fat pads and livers of female Sprague-Dawley rats.

Animals↗
PubMed1989

Calorie restriction delays age-dependent loss in androgen responsiveness of the rat liver.

We have shown that restricted calorie intake retards age-associated loss in androgen responsiveness of the rat liver. Sustained androgen receptivity delays age-dependent decline in the synthesis of the androgen-inducible alpha 2u globulin and derepression of the androgen-repressible senescence marker protein (SMP-2). Quantitation of mRNAs for alpha 2u globulin and SMP-2 in the liver of animals of various ages maintained on either ad libitum or restricted diets revealed that, although the 27-month-old ad libitum-fed rat had only 5% as much alpha 2u mRNA as the 6-month-old rat, the mRNA level was as high as 45% in the 27-month-old food-restricted rat. Conversely, the 27-month-old food-restricted rat had a much reduced amount (45%) of SMP-2 mRNA compared to the age-matched control that was allowed unlimited access to food. Furthermore, we have correlated the effect of dietary restriction on age-dependent changes in specific gene expression with the hepatic level of the immunoreactive cytoplasmic androgen-binding (CAB) protein. We observed that senescence in the male causes a substantial decrease in the circulating level of testosterone. However, dietary restriction does not retard the rate of decline in the plasma level of the male hormone during aging. These results indicate that age-dependent changes in the expression of androgen-responsive genes (alpha 2u globulin and SMP-2) reflect changing androgen sensitivity and that food restriction may directly influence the androgen receptivity of the liver.

Aging↗
PubMed1989

Effect of temperature on aflatoxin production in Mucuna pruriens seeds.

This paper describes the effect of temperature on the level of aflatoxin production in Mucuna pruriens seeds. The highest level of aflatoxin B1 (1.75 micrograms/g) was detected in the samples incubated at 25 degrees C for three weeks. At 20, 30, and 35 degrees C, aflatoxin levels were 0.30 to 0.56, 0.37 to 1.20, and 0.26 to 0.65 micrograms/g, respectively. The lowest concentration of aflatoxin B1 (0.10 to 0.29 microgram/g) was produced at 15 degrees C.

Aflatoxins↗
PubMed1989

Alpha 2u-globulin in modified sebaceous glands with pheromonal functions: localization of the protein and its mRNA in preputial, meibomian, and perianal glands.

alpha 2u-Globulin, the principal urinary protein of the male rat, has extensive sequence homology with many lipid binding proteins. The highest concentration of alpha 2u-globulin is found in the preputial gland, a holocrine secretory organ with pheromonal function. Meibomian and perianal glands are two other modified sebaceous glands with holocrine secretory cycles and pleiomorphic peroxisomes capable of synthesizing pheromonal lipids. Immunocytochemical examination shows the presence of alpha 2u-globulin in the acinar cells of all three of these modified sebaceous glands. Whereas in the preputial gland all of the acinar cells exhibit immunoreactivity, in the meibomian and perianal glands only selective cells contain alpha 2u-globulin. In the case of the preputial gland, in addition to the acinar cells some stratified epithelial cells also were immunoreactive. In the perianal and meibomian glands, keratinocytes lining nearby hair shafts and select cells of accessory oil glands stained for alpha 2u-globulin. In situ hybridization with a cloned cRNA probe confirmed the immunocytochemical data. Presence of the alpha 2u-globulin mRNA in these glands was also established by Northern blot analysis. Immunoelectron microscopic examination of preputial alpha 2u-globulin showed the presence of this protein in secretory granules of various maturational stages. Immunolabeled alpha 2u was also found in attached vesicles containing protein and lipid inclusions. The lytic cells were not only loaded with alpha 2u-globulin but also contained sharp-edged, irregularly shaped electron-dense granules which stained heavily for this protein. Specific localization of alpha 2u-globulin and its mRNA in three pheromone-producing sebaceous glands and its structural homology with known lipid binding proteins indicate a pheromone carrier role of alpha 2u-globulin.

Alpha-Globulins↗
PubMed1989

Loss of androgenic induction of alpha 2u-globulin gene family in the liver of NIH black rats.

Unlike all known strains of rat, the androgen-inducible alpha 2u-globulin gene family is totally silent in the liver of NIH black (NB) rats. No endocrinological or reproductive abnormalities are apparent, and the mRNA for the androgen-repressible hepatic protein SMP-2 is normally regulated in these animals. Furthermore, immunoblot analysis shows a normal level of the male-specific cytoplasmic androgen-binding protein. Cross-breeding of the NB male and Sprague-Dawley female shows that the hybrid male in the F-1 generation regains the androgen-dependent expression of alpha 2u-globulin in the liver. These results along with the observation of high constitutive level of alpha 2u-globulin mRNA in the preputial gland of NB rats indicate a tissue- and gene-specific regulatory defect which prevents androgenic induction of alpha 2u-globulin in the liver.

Alpha-Globulins↗
PubMed1988

Cloning, sequencing, and regulation of rat liver carnitine octanoyltransferase: transcriptional stimulation of the enzyme during peroxisome proliferation.

Several complementary DNAs for the peroxisomal enzyme carnitine octanoyltransferase (COT), cloned in the expression vector lambda gt11, have been isolated. Together, these clones cover 2143 bp of the COT cDNA sequence with an open reading frame for 523 amino acids. Northern analysis showed the mRNA size for this enzyme to be 3.5 kilobases. The 523 residue long amino acid sequence amounts to a molecular mass of 60,269 daltons, indicating that the cloned cDNAs contain most or all of the coding sequence for COT (Mr approximately 62,000). Hybridization studies showed that the increased COT activity in the liver of rats, fed the potent peroxisome-proliferating drug Wy-14,643, is associated with a more than 40-fold rise in the steady-state level of the COT mRNA.

Acyltransferases↗
PubMed1988

Changes in transcriptional activity and matrix association of alpha 2u-globulin gene family in the rat liver during maturation and aging.

Hepatic synthesis of alpha 2u-globulin in the male rat begins at puberty (about 40 days), reaches a peak level at about 80 days, and ceases at about 750-800 days of age. The age-dependent changes in alpha 2u-globulin synthesis are correlated with both the steady-state level of the hepatic mRNA for this protein and the rate of transcription of the alpha 2u-globulin gene family. Transcriptional activation of the alpha 2u-globulin gene family at puberty and cessation of transcription at senescence correlate with the association and dissociation of this gene domain with the nuclear matrix. Unlike the alpha 2u-globulin gene, the albumin gene in the liver shows preferential association with the nuclear matrix throughout the life. From these results we conclude that the age-dependent changes in alpha 2u-globulin synthesis are due to the alteration in the rate of transcription of the alpha 2u-globulin gene, and that the association of this gene domain to the nuclear matrix is a prerequisite to its transcriptional activation.

Aging↗