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Biomedical subjects

R Sanyal

Publications and source records attributed to R Sanyal.

At least 19 recordsLinked to original sources
PubMed2006

Giant congenital intrapericardial left atrial aneurysm diagnosed by contrast-enhanced computed tomography.

A left atrial aneurysm is a rare cardiac anomaly. The etiology is usually congenital, but it can also occur as an acquired pathology secondary to mitral valve disease or a degenerative process. We report a case which, on routine PA chest radiography, presented as cardiomegaly with a bulge on the left cardiac contour. Further evaluation by contrast-enhanced computed tomography proved it to be caused by a large left atrial aneurysm.

Adult↗
PubMed2006

CT appearances of hydatid disease at various locations.

Hydatid disease has characteristic imaging features on CT, which allow accurate preoperative diagnosis in most cases. However, when it occurs at unusual locations the diagnosis is often difficult, especially as the imaging appearance varies at different sites. In this article we have presented a pictorial review of the CT features of disease due to Echinococcus granulosus at various sites in the human body.

Animals↗
PubMed2006

Primary extragonadal retroperitoneal teratoma in an adult.

Primary retroperitoneal teratoma is a rare entity in adults. It has a distinctive imaging appearance. We describe a case of a 22-year-old patient who was referred to our hospital with the complaint of abdominal distension. Radiological work-up disclosed a retroperitoneal teratoma. Laparotomy with tumour resection was performed. Pathological examination revealed a benign cystic teratoma. The patient is doing well at follow-up.

Adult↗
PubMed2005

Pseudocyst formation: a rare complication of wandering spleen.

Wandering spleen is a rare entity, in which the spleen is abnormally mobile due to its attachment by a long vascular pedicle. This long vascular pedicle predisposes it to various complications, the most common being torsion. Here, we present a case in which a wandering spleen in a young female was complicated by pseudocyst formation, and discuss the possible aetiology, pathogenesis, diagnosis and therapeutic implications of this extremely rare complication.

Abdominal Pain↗
PubMed2002

Hormonal mechanisms regulating hepatic vitellogenin synthesis in the gilthead sea bream, Sparus aurata.

Experiments were carried out to study in vitro the effects of 17beta-estradiol (E(2)), homologous pituitary homogenate (HPH), and recombinant red sea bream growth hormone (sbGH) on vitellogenin (VTG) secretion from cultured sea bream liver fragments. Basal secretion of VTG was found to be significantly higher in the prespawning period, compared with sea bream liver in the spawning and postspawning periods. Similarly, the sea bream liver obtained during the prespawning period responded more significantly to treatments with E(2), HPH, or sbGH compared with sea bream liver during spawning. In the postspawning period, treatments with E(2), HPH, or sbGH were without significant effect on VTG secretion level in sea bream liver. The level of E(2) receptors was also analyzed by Western blot analysis. The result demonstrates a significantly higher level of E(2) receptors in the sea bream liver at the prespawning stage compared with those at the spawning and postspawning stages. The findings support the hypothesis that homologous upregulation of estrogen receptors plays an important role in the estrogen-sensitive control of VTG synthesis in the sea bream liver.

Animals↗
PubMed2000

Hepatopulmonary syndrome in inferior vena cava obstruction responding to cavoplasty.

Reports show that hepatopulmonary syndrome mostly occurs in the setting of advanced hepatic dysfunction, with the associated vasoactive substance imbalance believed to be responsible for its pathogenesis. However, hepatopulmonary syndrome has also been reported in cases of mild hepatic dysfunction or noncirrhotic portal hypertension, indicating that portal hypertension also plays a part in the pathogenesis. Liver transplantation remains the only therapeutic option of proven benefit. We describe 2 cases of hepatopulmonary syndrome in the setting of inferior vena cava (suprahepatic) obstruction, but with minimal hepatic dysfunction. After balloon cavoplasty, 1 patient showed, in addition to improvement of the features of hepatic outflow obstruction, significant reduction of dyspnea, cyanosis, and hypoxemia with arterial blood gas normalization within 2 weeks and intrapulmonary shunt reversal within 8 weeks. This implies that hemodynamic alterations (such as portal hypertension) independently contribute to the pathogenesis of hepatopulmonary syndrome in at least some of the cases. Therapies aimed at correcting these abnormal hemodynamics may be important in the treatment of this condition, especially when the hepatic functional status by itself does not warrant a liver transplant.

Adult↗
PubMed1999

Genotoxic effects of heterocyclic aromatic amines in human derived hepatoma (HepG2) cells.

In order to study the mutagenic effects of heterocyclic aromatic amines (HAAs) in cells of human origin, five compounds, namely 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), 2-amino-3, 4-dimethyl-imidazo[4,5-f]quinoline (MeIQ), 2-amino-3, 8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), the pyridoimidazo derivative 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), were tested in micronucleus (MN) assays with a human derived hepatoma (HepG2) cell line. All HAAs caused significant, dose-dependent effects. The activities of IQ, MeIQ, MeIQx and PhIP were similar (lowest effective concentrations 25-50 microM), whereas Trp-P-1 was effective at a dose of >/=2.1 microM. In addition, the HAAs were tested in MN assays with Chinese hamster ovary (CHO) cells and in Salmonella strain YG1024 using HepG2 cell homogenates as an activation mix. In the CHO experiments, positive results were obtained with Trp-P-1 and PhIP, whereas the other compounds were devoid of activity under all experimental conditions. The discrepancy in the responsivity of the two cell lines is probably due to differences in their acetylation capacity: enzyme measurements with 2-aminofluorene as a substrate revealed that the cytosolic acetyltransferase activity in the HepG2 cells is approximately 40-fold higher than that of the CHO cells. In the bacterial assays all five HAAs gave positive results but the ranking order was completely different from that seen in the HepG2/MN experiments (IQ > MeIQ > Trp-P-1 >/= MeIQx >> PhIP) and the mutagenic potencies of the various compounds varied over several orders of magnitude. The order obtained in bacterial tests with rat liver S9 mix was more or less identical to that seen in the tests with HepG2 cell homogenates but the concentrations of the amines required to give positive results were in general substantially lower (10(-5)-10(-1) microM). Overall, the results of the present study indicate that MN/HepG2 tests might reflect the mutagenic effects of HAAs more adequately than other in vitro mammalian cell systems due to the presence of enzymes involved in the metabolic conversion of the amines.

Amines↗
PubMed1999

Development of test systems for the detection of compounds that prevent the genotoxic effects of heterocyclic aromatic amines: preliminary results with constituents of cruciferous vegetables and other dietary constituents.

Over the past decades, strong efforts have been made to identify dietary constituents that protect against the genotoxic effects of heterocyclic aromatic amines (HAAs). However, most of the methods that have been used, in particular in vitro assays that require the addition of exogenous enzyme homogenates, have only a limited predictive value because important protective mechanisms are not adequately represented and may give misleading results. Therefore, we attempted to develop improved test systems, namely assays, with human hepatoma cells and single-cell gel electrophoresis (SCGE) tests with rats. Genotoxicity tests with human derived Hep G2 cells reflect the genotoxic effects of HAAs better than other in vitro systems. They also enable the detection of protective effects since the human derived hepatoma cells possess phase I and phase II enzymes that are involved in the activation/ detoxification of the amines. The most appropriate endpoint for experiments with Hep G2 cells appears to be micronucleus induction, but protocols for other endpoints are available as well. The second promising model is the SCGE ("comet") assay with rats that was used successfully to measure protective effects of constituents of cruciferous vegetables against 2-amino-3-methylimidazo[4,5-flquinoline (IQ) in the liver and in the colon mucosa. The present study describes the experimental design of the new approaches, as well as results obtained with various dietary constituents.

Animals↗
PubMed1998

Use of metabolically competent human hepatoma cells for the detection of mutagens and antimutagens.

The human hepatoma line (Hep G2) has retained the activities of various phase I and phase II enzymes which play a crucial role in the activation/detoxification of genotoxic procarcinogens and reflect the metabolism of such compounds in vivo better than experimental models with metabolically incompetent cells and exogenous activation mixtures. In the last years, methodologies have been developed which enable the detection of genotoxic effects in Hep G2 cells. Appropriate endpoints are the induction of 6-TGr mutants, of micronuclei and of comets (single cell gel electrophoresis assay). It has been demonstrated that various classes of environmental carcinogens such as nitrosamines, aflatoxins, aromatic and heterocyclic amines and polycyclic aromatic hydrocarbons can be detected in genotoxicity assays with Hep G2 cells. Furthermore, it has been shown that these assays can distinguish between structurally related carcinogens and non-carcinogens, and positive results have been obtained with rodent carcinogens (such as safrole and hexamethylphosphoramide) which give false negative results in conventional in vitro assays with rat liver homogenates. Hep G2 cells have also been used in antimutagenicity studies and can identify mechanisms not detected in conventional in vitro systems such as induction of detoxifying enzymes, inactivation of endogenously formed DNA-reactive metabolites and intracellular inhibition of activating enzymes.

Animals↗
PubMed1998

Isolation, characterization and disruption of the casein kinase II alpha subunit gene of Leishmania chagasi.

To elucidate the role played by casein kinase II in Leishmania survival, we have isolated and characterized the Leishmania chagasi casein kinase II alpha subunit cDNA, (L.c CKIIalpha). The 1083 bp coding region is flanked by 148 bp of 5' UTR and 1155 bp of 3' UTR. L.c CKIIalpha shows a remarkable degree of similarity with other isolated casein kinase II alpha subunit sequences. L.c CKIIalpha protein is encoded by a single copy gene that transcribes a mRNA of 2.4 kb. The 41.2 kDa L.c CKIIalpha protein expressed in vitro has been shown to be catalytically active. A single allele disruption of the L.c CKIIalpha gene that removes 94 bp from the coding region which contains one of the 15 conserved amino acids closest to the carboxy-terminus of the protein has been generated. This mutant is viable and results in a reduction of L.c CKIIalpha transcript levels over 14-fold and that of an iron superoxide dismutase mRNA by 5-fold. As well, the kinase activity of the single allele disrupted cells showed a 3-fold reduction as compared to the wild type cells suggesting a decrease in activity of the L.c CkIIalpha enzyme.

Alleles↗
PubMed1997

Comparison of multiplane and biplane transesophageal echocardiography in the assessment of aortic stenosis.

The aim of the study was to compare the accuracy of multiplane transesophageal echocardiography (TEE) with the more conventional biplane technique in the direct assessment of aortic valve area in patients with aortic stenosis. Short-axis images of the aortic valve adequate for measuring aortic valve area were obtained in all 81 patients studied by multiplane TEE but in only 56 of 64 patients (88%) using the biplane approach. The correlation coefficient for aortic valve area determined by multiplane TEE (r = 0.89; SEE = 0.04 cm2) was higher (p < 0.01) than biplane TEE (r = 0.74; SEE = 0.06 cm2). Correlations were higher for bicuspid valves (multiplane, r = 0.93; biplane, r = 0.75) than tricuspid valves (multiplane, r = 0.87; biplane, r = 0.75). Our study has demonstrated the superiority of multiplane TEE to both biplane TEE and transthoracic echocardiography (TTE) in the direct evaluation of aortic valve area in patients with aortic stenosis.

Adult↗
PubMed1997

Inhibition of the genotoxic effects of heterocyclic amines in human derived hepatoma cells by dietary bioantimutagens.

The effects of dietary bioantimutagens (compounds which have been shown to inhibit mutagenesis via interaction with DNA repair processes) on spontaneous and heterocyclic amine (HCA)-induced micronucleus (MN) frequencies were studied in metabolically competent human hepatoma (Hep-G2) cells. All the compounds tested (coumarin, vanillin, caffeine, tannic acid and cinnamaldehyde) caused a moderate increase of MN numbers in Hep-G2 cells at high concentrations (500 microg/ml); only tannic acid was also active at lower dose levels. In combination experiments with the HCA 2-amino-3-methylimidazo-[3,4-f]quinoline (IQ), post-treatment of the cells with bioantimutagens resulted in a pronounced (75-90%) decrease in MN. The most drastic effects were seen with vanillin, coumarin and caffeine which were active at concentrations < or = 5 microg/ml. Further experiments indicated that these compounds also attenuate the mutagenic effects of other HCAs (PhIP, MeIQ, MeIQx, Trp-P-1).

Acrolein↗
PubMed1996

Effects of phenethyl isothiocyanate on metabolism and on genotoxicity of dimethylnitrosamine and 2-amino-1-methyl-6-phenylimidazo[4, 5-beta]pyridine (PhIP).

Phenethyl isothiocyanate (PEITC), a constituent of cruciferous vegetables, inhibited the genotoxic effects of N-nitrosodimethylamine (DMN) and of 2-amino-1-methyl-6-phenylimidazo[4,5-beta]pyridine (PhIP) in differential DNA repair assays with E. coli K-12 strains in vitro and in animal mediated assays with mice. In Salmonella typhimurium, the mutagenic activities of DMN and PhIP measured after activation with S-9 homogenates from several organs of PEITC-treated mice were substantially lower than those obtained with homogenates of untreated animals as well. PEITC also reduced the formation of micronuclei by DMN in metabolically competent Hep-G-2 cells of human origin but was ineffective in combination with PhIP. Biochemical investigations showed that the prevention of genotoxic effects of DMN by PEITC results form an inhibition of its alpha-hydroxylation. The effect of oral administration of PEITC on the formation of DNA adducts of PhIP was examined in the colon and liver of mice. No inhibition of adduct formation was observed in these experiments. Biochemical experiments showed that PEITC reduces not only the metabolic activation of PhIP via 2-hydroxyamino PhIP but also inhibits a detoxification pathway (formation of 4-hydroxy PhIP). The present results can be taken as an indication that the anticarcinogenic activities of isothiocyanates towards nitrosamines are paralleled by antimutagenic effects, and that probably no such protective effects occur in combination with heterocyclic amines. Furthermore, our findings show that the effects of chemopreventive agents demonstrated in bacteria in vitro cannot always be extrapolated to reactions occurring in intact mammalian cells.

Animals↗
PubMed1992

Three-dimensional and four-dimensional transesophageal echocardiographic imaging of the heart and aorta in humans using a computed tomographic imaging probe.

We evaluated the clinical applicability of a prototype tomographic transesophageal echocardiographic (TEE) system, which not only provides conventional TEE images but also three-dimensional tissue reconstruction and four-dimensional display capabilities. The probe was used in 16 patients in the echocardiographic laboratory, intensive care unit, and the operating room. The instrument is a 5-MHz, 64-element, phased array unit mounted on a sliding carriage within a casing. After appropriate probe placement within the esophagus, the probe is straightened, a balloon surrounding the probe is inflated, and data acquisition begun with ECG and respiration gating. With computer controlled transducer movement at 1-mm increments, a complete cardiac cycle is recorded at each tomographic level. These are processed using a dedicated four-dimensional software, and displayed as a dynamic three-dimensional tissue image of the heart. We were able to see the dynamic motion of the ventricles and all the valves in the four-dimensional format. In addition to four-dimensional display, we were able to cut and visualize the heart in dynamic mode in any desired plane and also in multiple planes. Patients tolerated the procedure well. We conclude that this tomographic four-dimensional approach, which does not require tedious off-line processing, can easily be performed in patients and has a strong clinical potential.

Aorta↗