Biomedical subjects

B Joseph

Publications and source records attributed to B Joseph.

At least 19 recordsLinked to original sources

PubMed2006

The role of p73 in hematological malignancies.

The P73 gene is a homologue of the P53 tumor suppressor. Owing to its structural similarity with p53, p73 was originally considered to have tumor suppressor function. However, the discovery of N-terminal truncated isoforms with oncogenic properties showed a 'two in one' structure of its product, p73 protein. The full-length variants are strong inducers of apoptosis, whereas the truncated isoforms inhibit proapoptotic activity of p53 and the full-length p73. Thus, p73 is involved in the regulation of cell cycle, cell death and development. Moreover, it plays a role in carcinogenesis and controls tumor sensitivity to treatment. p73 is commonly expressed in tumor cells in hematological malignancies. Overexpression of p73 protein and aberrant expression of its particular isoforms, with very low frequency of P73 hypermethylation or mutations, were found in malignant myeloproliferations, including acute myeloblastic leukemia. In contrast, hypermethylation and subsequent inactivation of the P73 gene are the most common findings in malignant lymphoproliferative disorders, especially acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphomas. Assessment of P73 methylation may provide important prognostic information, as was confirmed in patients with ALL. This review summarizes some aspects of p73 biology with particular reference to its possible pathogenetic role and prognostic significance in hematological malignancies.

Alternative Splicing↗

PubMed2006

Overexpression of PrfA leads to growth inhibition of Listeria monocytogenes in glucose-containing culture media by interfering with glucose uptake.

Listeria monocytogenes strains expressing high levels of the virulence regulator PrfA (mutant PrfA* or wild-type PrfA) show strong growth inhibition in minimal media when they are supplemented with glucose but not when they are supplemented with glucose-6-phosphate compared to the growth of isogenic strains expressing low levels of PrfA. A significantly reduced rate of glucose uptake was observed in a PrfA*-overexpressing strain growing in LB supplemented with glucose. Comparative transcriptome analyses were performed with RNA isolated from a prfA mutant and an isogenic strain carrying multiple copies of prfA or prfA* on a plasmid. These analyses revealed that in addition to high transcriptional up-regulation of the known PrfA-regulated virulence genes (group I), there was less pronounced up-regulation of the expression of several phage and metabolic genes (group II) and there was strong down-regulation of several genes involved mainly in carbon and nitrogen metabolism in the PrfA*-overexpressing strain (group III). Among the latter genes are the nrgAB, gltAB, and glnRA operons (involved in nitrogen metabolism), the ilvB operon (involved in biosynthesis of the branched-chain amino acids), and genes for some ABC transporters. Most of the down-regulated genes have been shown previously to belong to a class of genes in Bacillus subtilis whose expression is negatively affected by impaired glucose uptake. Our results lead to the conclusion that excess PrfA (or PrfA*) interferes with a component(s) essential for phosphotransferase system-mediated glucose transport.

Base Sequence↗

PubMed2005

Transplantation of endothelial cells corrects the phenotype in hemophilia A mice.

BACKGROUND: The deficiency of factor VIII, a co-factor in the intrinsic coagulation pathway results in hemophilia A. Although FVIII is synthesized largely in the liver, the specific liver cell type(s) responsible for FVIII production is controversial. OBJECTIVE: This study aimed to determine the cellular origin of FVIII synthesis and release in mouse models. METHODS: We transplanted cells into the peritoneal cavity of hemophilia A knockout mice. Plasma FVIII activity was measured using a Chromogenix assay 2-7 days after cell transplantation, and phenotypic correction was determined with tail-clip challenge 7 days following cell transplantation. Transplanted cells were identified by histologic and molecular assays. RESULTS: Untreated hemophilia A mice, as well as mice treated with the hepatocyte-enriched fraction, showed extensive mortality following tail-clip challenge. In contrast, recipients of unfractionated liver cells (mixture of hepatocytes, liver sinusoidal endothelial cells (LSEC), Kupffer cells, and hepatic stellate cells) or of the cell fraction enriched in LSECs survived tail-clip challenge (P < 0.001). FVIII was secreted in the blood stream in recipients of unfractionated liver cells, LSECs and pancreatic islet-derived MILE SVEN 1 (MS1) endothelial cells. Although transplanted hepatocytes maintained functional integrity in the peritoneal cavity, these cells did not produce detectable plasma FVIII activity. CONCLUSIONS: The assay of cell transplantation in the peritoneal cavity showed that endothelial cells but not hepatocytes produced phenotypic correction in hemophilia A mice. Therefore, endothelial cells should be suitable additional targets for cell and gene therapy in hemophilia A.

Animals↗

PubMed2003

ompU genes in non-toxigenic Vibrio cholerae associated with aquaculture.

AIMS: The study was undertaken with the objective of understanding the virulence-associated genes of the CTX and TCP gene clusters in environmental isolates of Vibrio cholerae, an important human pathogen, isolated from the aquaculture environment. The involvement of the ompU gene in conferring bile resistance in these isolates was also evaluated. METHODS AND RESULTS: The V. cholerae isolates were tested by PCR and fluorescent antibody test for O1 (Ogawa and Inaba) and O139 serotypes. All isolates were found to be non-toxigenic V. cholerae confirmed by their positive PCR reaction for toxR but negative for ctx, zot and tcp gene. The hlyA gene was detected in 85% of the strains and ompU in 77%. The results on the bactericidal effect of bile salts suggest that ompU may play a role in conferring bile resistance in non-O1/non-O139 strains. CONCLUSION: The results of the study indicate that most environmental strains lacked the CTX and TCP gene clusters. However, most isolates had the hlyA gene indicating the potential of these environmental strains to cause mild gastroenteritis. It was also observed that strains lacking ompU showed less tolerance to bile salts. SIGNIFICANCE AND IMPACT OF THE STUDY: Information on virulence factors of V. cholerae associated with aquaculture environment and products would be of value in risk assessment for human health.

Adhesins, Bacterial↗

PubMed2002

Consanguinity and ocular genetic diseases in South India: analysis of a five-year study.

OBJECTIVE: Consanguineous marriage is a widely practised social custom in Asia and northern Africa. In south India, Dravidian Hindus have contracted consanguineous marriages for over 2,000 years. In the present study, the influence of consanguinity on the prevalence of visual disorders was examined in patients attending a specialist genetic eye clinic. SUBJECTS AND METHODS: A total of 2,335 patients attending Sankara Nethralaya, Chennai, India, were screened for genetic eye disorders over a five-year period. The patients were drawn from all parts of India and from neighbouring countries in south Asia. RESULTS AND DISCUSSION: Six hundred and seventy-three (28.8%) of the patients tested for ophthalmic genetic disorders reported a family history of consanguinity. The majority (n = 574) of these families were from south India. In the patient group as a whole, the most common form of consanguineous union was between first cousins (n = 367), followed by uncle/niece marriage (n = 177), equivalent to a mean coefficient of inbreeding alpha = 0.0202. Among the consanguineous families, 430 of 673 (63.9%) had retinitis pigmentosa, 167 of these cases were autosomal recessive and 199 were isolated cases. The public in regions such as south India should be made aware of the merits and demerits of consanguineous marriages.

Journal Article↗

PubMed2001

Induction of cell cycle arrest and morphological differentiation by Nurr1 and retinoids in dopamine MN9D cells.

Dopamine cells are generated in the ventral midbrain during embryonic development. The progressive degeneration of these cells in patients with Parkinson's disease, and the potential therapeutic benefit by transplantation of in vitro generated dopamine cells, has triggered intense interest in understanding the process whereby these cells develop. Nurr1 is an orphan nuclear receptor essential for the development of midbrain dopaminergic neurons. However, the mechanism by which Nurr1 promotes dopamine cell differentiation has remained unknown. In this study we have used a dopamine-synthesizing cell line (MN9D) with immature characteristics to analyze the function of Nurr1 in dopamine cell development. The results demonstrate that Nurr1 can induce cell cycle arrest and a highly differentiated cell morphology in these cells. These two functions were both mediated through a DNA binding-dependent mechanism that did not require Nurr1 interaction with the heterodimerization partner retinoid X receptor. However, retinoids can promote the differentiation of MN9D cells independently of Nurr1. Importantly, the closely related orphan receptors NGFI-B and Nor1 were also able to induce cell cycle arrest and differentiation. Thus, the growth inhibitory activities of the NGFI-B/Nurr1/Nor1 orphan receptors, along with their widespread expression patterns both during development and in the adult, suggest a more general role in control of cell proliferation in the developing embryo and in adult tissues.

Animals↗

PubMed2001

Defective caspase-3 relocalization in non-small cell lung carcinoma.

Many anticancer drugs exert their cytotoxicity through DNA damage and induction of apoptosis. Small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC) have different sensitivity to treatment with radiation and chemotherapeutic agents with SCLC being more sensitive than NSCLC both in vitro and in vivo. This difference might be related to the different susceptibility of small and non-small cell lung carcinoma to undergo apoptosis. The aim of this study was to investigate if deficiencies in the apoptotic pathways can explain the intrinsic resistance of NSCLC to anti-cancer treatment. Three different triggers were used to induce apoptosis. Etoposide and gamma-radiation, which are important parts of clinical lung cancer treatment, induce DNA-damage, whereas Fas ligation induces receptor-mediated apoptotic pathways. NSCLC cells were cross-resistant to all treatments, whereas SCLC cells, which do not express pro-caspase-8, were resistant to alphaFas-, but not to DNA-damage-induced apoptosis. Cytochrome c release, activation of caspase-9 and the executioner caspase-3 were observed in both types of lung cancer cells. However, cleavage of known nuclear substrates for caspase-3, such as PARP and DFF45/ICAD, was documented only in the sensitive SCLC cells but not in the resistant NSCLC cells. Moreover, relocalization of active caspase-3 from the cytosol into the nucleus upon treatment was observed only in the SCLC cell line. These results indicate that the inhibition of apoptosis in NSCLC occurs downstream of mitochondrial changes and caspase activation, and upstream of nuclear events.

Apoptosis↗

PubMed2001

Biofilm formation by salmonella spp. on food contact surfaces and their sensitivity to sanitizers.

Biofilm formation by two poultry isolates of Salmonella on three commonly used food contact surfaces viz plastic, cement and stainless steel were studied. Biofilm formation of both the isolates showed a similar trend with the highest density being on plastic followed by cement and steel. Salmonella weltevreden formed biofilm with a cell density of 3.4 x 10(7), 1.57 x 10(6) and 3 x 10(5) cfu/cm2 on plastic, cement and steel respectively while Salmonella FCM 40 biofilm on plastic, cement and steel were of the order of 1.2 x 10(7), 4.96 x 10(6) and 2.23 x 10(5) cfu/cm2 respectively. The sensitivity of the biofilm cells grown on these surfaces to different levels of two sanitizers namely hypochlorite and iodophor for varying exposure times was studied. Biofilm cells offered greater resistance when compared to their planktonic counterparts. Such biofilm cells in a food processing unit are not usually removed by the normal cleaning procedure and therefore could be a source of contamination of foods coming in contact with such surfaces.

Animals↗

PubMed2001

Possible dosage effect of maternally expressed genes on visual recognition memory in Prader-Willi syndrome.

Seventeen patients with Prader-Willi syndrome (7 with paternal deletion of chromosome 15q11-q13 and 10 with maternal uniparental disomy [UPD]), and 9 controls performed a computerized visual recognition task. A series of color digital photographs were presented; most were presented twice, but the remainder appeared only once. Photographs presented twice were separated in their presentation by either 0, 10, 30, 50 or 100 intervening photographs. Subjects indicated whether each photograph had been presented previously. This procedure was implemented twice, once using photographs of foods, and once using photographs of nonfood objects. As the number of intervening photographs between the first and second presentation increased, subjects were less likely to remember having seen the photograph before. Performance by UPD subjects was less affected by increasing the number of intervening photographs relative to the other two groups, suggesting they had superior visual recognition memory. This raises the possibility of a beneficial effect of having two copies maternally expressed genes on chromosome 15. UBE3A is suggested as a possible candidate for this effect.

Adolescent↗

PubMed2001

Tumor necrosis factor allelic polymorphism with diabetic retinopathy in India.

The association of tumor necrosis factor (TNF) with diabetic retinopathy (DR) has been described previously. A total of 207 Asian Indian patients of 15-year duration of type 2 diabetes were identified. This group included (i) 100 patients with DR and (ii) 107 patients without retinopathy (DNR). In this study, we correlated the length of the (GT)n microsatellite di-nucleotide repeat upstream to the promoter region of TNF gene with susceptibility for the development of retinopathy. The microsatellite was polymerase chain reaction amplified and electrophoresed on polyacrylamide gel and silver stained. In our study population, there were 18 alleles ranging from 97 to 131 base pairs (bp). Allele 4 (103 bp) had a higher prevalence (9.81%) in the DNR group compared to that (2.5%) in the DR group (P=0.002). Patients with retinopathy and allele 8 (111 bp) had a tendency to develop proliferative diabetic retinopathy (PDR). In this study of Indian subjects, it is suggested that allele 4 is a low risk allele for developing retinopathy and allele 8 (111 bp) shows an association with PDR.

Alleles↗

PubMed2001

Synthesis, cytotoxicity, DNA interaction and topoisomerase II inhibition properties of tetrahydropyrrolo[3,4-a]carbazole-1,3-dione and tetrahydropyrido-[3,2-b]pyrrolo[3,4-g]indole-1,3-dione derivatives.

Three tetrahydropyrrolo[3,4-a]carbazole-1,3-diones (6--8) and two tetrahydropyrido[3,2-b]pyrrolo[3,4-g]indole-1,3-diones (11--12) have been synthesized. Their interaction with DNA was probed by absorption and thermal melting studies. Compounds 8 and 12 both equipped with a hydroxyethyl-aminoethyl side-chain demonstrated higher affinities for poly(dA-dT)(2) than compounds 6, 7 and 11 bearing a dimethylaminoethyl side-chain. Circular and electric linear dichroism measurements showed that all five drugs behave as typical DNA intercalating agents. A plasmid cleavage assay was used to evaluate the capacity of the drugs to inhibit human topoisomerase II. Compounds 8 and 12 which bind strongly to DNA were found to stabilize DNA-topoisomerase II covalent complexes but their topoisomerase II inhibitory properties do not correlate with their cytotoxic potential. Compounds 6 and 7 are essentially inactive whereas compounds 8, 11 and 12 exhibit a high toxicity to P388 murine leukemia cells and provoke a marked accumulation in the G2/M phase of the cell cycle. These compounds form a new class of DNA-targeted antitumor agents.

Animals↗

PubMed2001

Granulocyte colony-stimulating factor inhibits Fas-triggered apoptosis in bone marrow cells isolated from patients with refractory anemia with ringed sideroblasts.

Treatment with granulocyte colony-stimulating factor (G-CSF) plus erythropoietin may synergistically improve hemoglobin levels and reduce bone marrow apoptosis in patients with refractory anemia with ringed sideroblasts (RARS). Fas-induced caspase activity is increased in RARS bone marrow cells. We showed that G-CSF significantly reduced Fas-mediated caspase-8 and caspase-3-like activity and the degree of nuclear apoptotic changes in bone marrow from nine RARS patients. A decrease in mitochondrial membrane potential and an increase in intracellular reactive oxygen species occurred in Fas-treated cells, but became significant only 24 h after changes in caspase activity and decrease in proliferation. G-CSF also reduced the magnitude of these late apoptotic changes. In CD34-selected normal cells, G-CSF induced myeloid colony growth, and an overall small decrease in the number of erythroid colonies. By contrast, G-CSF induced a 33-263% increase of erythroid colony formation in CD34+ cells from four of five RARS patients with severely reduced erythroid growth, while the normal or slightly reduced erythroid growth of three other patients was not influenced by G-CSF. This study suggests that G-CSF may reduce the pathologically increased caspase activity and concomitant apoptotic changes, and promote erythroid growth and differentiation of stem cells from RARS patients. Our data support the clinical benefit of G-CSF in this subgroup of myelodysplastic syndromes.

Aged↗

PubMed2001

High-LET radiation induces apoptosis in lymphoblastoid cell lines derived from atazia-telangiectasia patients.

PURPOSE: To investigate and compare the propensity of Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL), derived from ataxia-telangiectasia (A-T) patients and from unaffected healthy individuals (controls), to undergo apoptosis after exposure to high-linear energy transfer (LET) radiation. MATERIALS AND METHODS: Four A-T (ARO, BMA, CSA and RJO) and two control (JAC and KKB3) LCL were exposed to doses of up to 4Gy of accelerated nitrogen ions (32-45 MeV/u, 8-12Gy/min). For comparative purposes X-ray irradiation (1.36 Gy/min) was also performed. The induction of apoptosis was studied 0-48 h after irradiation with the use of two methods: (1) monitoring of high molecular weight (HMW) DNA fragments by field inversion pulse gel electrophoresis (FIGE); and (2) morphological characterization ofapoptotic cells after fluorescent staining. In parallel, cell-cycle distribution, monitored by DNA flow cytometry, as well as measurements of p53/p21(WAF1) protein levels by Western blots, were investigated in these cells. RESULTS: High-LET radiation-induced apoptosis and G2/M-arrest in both A-T and control LCL. No significant increase in the amount of p53/p21(WAF1) proteins preceded apoptosis in control or in A-T LCL after high-LET irradiation. However, low-LET radiation did induce significant enhanced levels of p53 proteins in control but not in A-T LCL. CONCLUSIONS: LCL from both A-T homozygous and unaffected healthy individuals undergo apoptosis without accumulation of p53/p21(WAF1) proteins after exposure to high-LET radiation. In contrast, low-LET radiation induces apoptosis and significantly increases levels of p53 protein in control but not in A-T LCL.

Apoptosis↗

PubMed2001

5-substituted 3,4-dihydro-3-amino-2H-1-benzopyran derivatives: synthesis and interaction with serotoninergic receptors.

A new series of 3,4-dihydro-3-amino-2H-1-benzopyran derivatives (1 and 2) bearing various substituents on the 5-position was successfully prepared via palladium-mediated cross-coupling reactions. Some of the new compounds showed high affinity for 5-HT1A and 5-HT7 receptors. The best affinity for the 5-HT1A and 5-HT7 receptors was obtained for 2b (Ki = 0.3 nM for 5-HT1A and 3.1 nM for 5-HT7). The anxiolytic activity of compound 2b was evaluated.

Animals↗

PubMed2001

Perthes' disease in the adolescent.

We studied the natural history of Perthes' disease in 62 children in whom the onset of symptoms was in adolescence. Three patterns of disease were noted, namely, late-onset pattern, segmental collapse, or destructive with failure of revascularisation. In the late-onset pattern, the disease followed the sequence of healing seen in younger children, but adequate epiphyseal remodelling did not occur. Consequently, the femoral head was never spherical after revascularisation. With segmental collapse, early and irreversible collapse of part of the epiphysis occurred with gross deformation of the femoral head. The destructive pattern was characterised by a failure of revascularisation and repair of the avascular epiphysis. The radiological outcome was poor in all three patterns. The poorest clinical results were found in the destructive type which was frequently associated with incapacitating pain requiring arthrodesis or excision arthroplasty within three years of onset of the disease.

Adolescent↗

PubMed2001

Pregnancy weight gain and its correlation to birth weight.

This study was done to determine whether a relationship existed between maternal weight gain during pregnancy and the birth weight and if such a relationship did exist, to establish the minimum weight gain required for a normal birth weight baby. This was a retrospective study involving an audit of all antenatal records at a rural hospital and health centre. The records reviewed belonged to a period between '86-'99. About 2000 antenatal records were scanned and cases with complications and multiple pregnancy were excluded. The records reviewed pertained only to mothers who had delivered at this rural hospital. The final sample size was 935 mothers. The study revealed that a greater weight gain in second trimester resulted in a better birth weight (P < 0.05). Other factors that influenced the birth weight were: age (P < 0.001), regular antenatal check up (P < 0.05) and parity (P < 0.05).

Adult↗

PubMed2000

Freezing induces artificial cleavage of apoptosis-related proteins in human bone marrow cells.

The aim of this study was to investigate whether freeze-thawing of freshly isolated human mononuclear bone marrow cells (MNC) influences the integrity of apoptosis-related proteins as determined by immunoblot analyses. Our results show that bone marrow is more sensitive to this process than either myelomonocytoid leukemic P39 or Jurkat T-lymphocyte cell lines. Specifically, bone marrow cells displayed a high level of intrinsic proteolytic activity in response to a single freeze-thaw cycle, which led to the cleavage of various proteins involved in apoptosis cell signaling. This effect was completely blocked by the inclusion of broad-spectrum protease inhibitors in the freezing medium and subsequently thawing the cells on ice. Since differences in the freezing conditions (-80 degrees C vs. liquid nitrogen) did not alter the proteins of interest, we suggest that the thawing process is the critical point when proteolytic enzyme activity is elevated.

Apoptosis↗

PubMed2000

A variant of Reinhardt-Pfeiffer mesomelic skeletal dysplasia.

Mesomelic bone dysplasias are characterised by disproportionate shortness of the middle segment of the extremities and short stature. Various patterns of this dysplasia have been described in the literature. The type involving mainly the ulna and fibula was described by Reinhardt and Pfeiffer as the ulno-fibular mesomelic dysplasia affecting the distal ulna and proximal fibula. Involvement of the distal fibula in mesomelic dysplasia has not been described to our knowledge. We report here a case of mesomelic dysplasia affecting mainly the distal fibula and distal ulna, with severe ankle deformity requiring surgical correction.

Acrocephalosyndactylia↗