Biomedical subjects

J Basu

Publications and source records attributed to J Basu.

At least 19 recordsLinked to original sources

PubMed2001

Lipoarabinomannan from Mycobacterium tuberculosis promotes macrophage survival by phosphorylating Bad through a phosphatidylinositol 3-kinase/Akt pathway.

Efforts in prevention and control of tuberculosis suffer from the lack of detailed knowledge of the mechanisms used by pathogenic mycobacteria for survival within host cell macrophages. The exploitation of host cell signaling pathways to the benefit of the pathogen is a phenomenon that deserves to be looked into in detail. We have tested the hypothesis that lipoarabinomannan (LAM) from the virulent species of Mycobacterium tuberculosis possesses the ability to modulate signaling pathways linked to cell survival. The Bcl-2 family member Bad is a proapoptotic protein. Phosphorylation of Bad promotes cell survival in many cell types. We demonstrate that man-LAM stimulates Bad phosphorylation in a phosphatidylinositol 3-kinase (PI-3K)-dependent pathway in THP-1 cells. Man-LAM activated PI-3K. LAM-stimulated phosphorylation of Bad was abrogated in cells transfected with a dominant-negative mutant of PI-3K (Delta p85), indicating that activation of PI-3K is sufficient to trigger phosphorylation of Bad by LAM. Since phosphorylation of Bad occurred at serine 136, the target of the serine/threonine kinase Akt, the effect of LAM on Akt kinase activity was tested. Man-LAM could activate Akt as evidenced from phosphorylation of Akt at Thr(308) and by the phosphorylation of the exogenous substrate histone 2B. Akt activation was abrogated in cells transfected with Deltap85. The phosphorylation of Bad by man-LAM was abrogated in cells transfected with a kinase-dead mutant of Akt. These results establish that LAM-mediated Bad phosphorylation occurs in a PI-3K/Akt-dependent manner. It is therefore the first demonstration of the ability of a mycobacterial virulence factor to up-regulate a signaling pathway involved in cell survival. This is likely to be one of a number of virulence-associated mechanisms by which bacilli control host cell apoptosis.

Carrier Proteins↗

PubMed2001

Preventable illness and out-of-area travel of children in New York counties.

The long-distance travellers could be important to any cost-benefit assessment of policies to increase or improve local resources. This study examines the out-of-area hospital admission pattern for patients with Ambulatory Care Sensitive (ACS) conditions, also known as preventable conditions. The availability of local resources play a significant role for hospitalization for these conditions. Despite a growing literature investigating hospital choice, little is known about the effects of resource availabilities in local areas and patient characteristics prompting people to seek care at a longer distance from home for these conditions. Based on hospital discharge data for New York residents (children) admitted to hospitals in New York, Pennsylvania, New Jersey or Connecticut in 1994, the study uses logistic regression to predict travel out of the local area for ACS admission. The actual distance between residence and hospital is a highly skewed and problematic measure, but the crossing of county boundaries is a related and very useful dichotomous measure of distant hospitalization. The study finds a strong association of types of insurance and availability of primary care with episodes of hospitalization for children outside the area of residence, after controlling for severity of illness and several other patient and county characteristics.

Ambulatory Care↗

PubMed2001

Apoptotic changes in cervical intraepithelial neoplasia.

We examined apoptosis in paraffin-embedded archival cervical tissues from cervical intraepithelial neoplasia (CIN) cases to determine whether the apoptotic process is involved in the cellular changes of CIN. Apoptotic bodies, determined by the Tunel method, were largely found at the surface epithelium in a few tissue specimens with no significant abnormality and in most tissues with CIN. Apoptotic bodies were also found within the stratified epithelium of CIN lesions and were altogether absent in specimens with no significant abnormalities. The apoptotic index was significantly associated with the severity of CIN and not with either age or human papillomavirus infection. Based on the findings of increased numbers of apoptotic bodies and their presence within the stratified epithelium in CIN tissues, we hypothesize that dysregulation in the exfoliation of apoptotic cells and resistance towards apoptosis may be prerequisites for the pathogenesis of CIN.

Adult↗

PubMed2001

Access to primary care: the role of race and income.

The study has two objectives: (1) to examine the racial differences in access provided by Municipal Health Services Clinics to the Medicare low-income beneficiaries, i.e., those also eligible for Medicaid (dual eligibles), and compare it with access provided to non-dually eligible patients; (2) to examine the racial and income disparities in access for primary and ancillary care services. The Municipal Health Services Program (MHSP) started in 1979 in five cities with the objective to improve access to primary care services. The study's method for measuring access combines use and need of care in a single index. The study finds that the clinics provided better access to dual eligibles than to non-dual eligibles and to nonwhite than to white dual eligibles. However, this was a result of higher use of ancillary services by the clinic nonwhite patients. This was particularly true in large clinics such as Baltimore, where inadequate targeting of the low-income group and higher ancillary use were more significant problems than racial disparity in access.

Black or African American↗

PubMed2001

Health insurance, primary care, and preventable hospitalization of children in a large state.

OBJECTIVES: To analyze variations in the admission rate to hospitals of children with ambulatory care-sensitive (ACS) conditions and to test the relationship of ACS admission rates to insurance coverage, health maintenance organization (HMO) enrollment, availability of primary care, severity of illness, distance to hospital, and a number of other factors. STUDY DESIGN: Hypotheses were derived from basic considerations about demand and use of primary care and preventive services and then were tested with a weighted linear regression model of the ACS admission rate for children residing in each county. PATIENTS AND METHODS: The principal data were all hospital discharges for New York resident children admitted to hospitals in New York, Pennsylvania, New Jersey, or Connecticut in 1994. The data and methodology were noteworthy for including out-of-area hospital admissions. RESULTS: There was a substantial negative association of the ACS rate with private HMO coverage. There also were sizable negative effects of the availability of primary care services in physician offices and the distance traveled. Large differences related to racial and ethnic composition of the population were found independent of other determinants. There was a positive association with the proportion of all admissions (admissions for all conditions) covered by Medicaid or self-pay. Severity of illness and use of emergency departments were controlled. There was no independent effect of a location in New York City. CONCLUSIONS: The results are consistent with smaller-scale studies suggesting that improved health insurance for children could reduce hospital admissions. Contracting with HMOs also appears to be beneficial. Independently, programs to increase the availability of primary and preventive services could substantially reduce ACS admissions.

Ambulatory Care↗

PubMed2001

Racial disparity, primary care, and specialty referral.

OBJECTIVE: The study examines the role of primary care physicians (PCP) in reducing racial disparities in referral-sensitive admissions. DATA SOURCES/STUDY SETTING: The study examined hospital discharges of New York residents in the age group 20 to 64 hospitalized either in New York or in any of three contiguous states -- New Jersey, Pennsylvania, or Connecticut -- using complete discharge files for the four states in 1995. The discharge data were linked to the Area Resource File and the American Hospital Association's survey files for 1995. STUDY DESIGN: The study used multivariate logistic models to compare the effect of PCP supply on referral-sensitive (discretionary) admissions versus marker admissions (urgent, in sensitive to primary care) or whites, blacks, and Hispanics. PRINCIPAL FINDINGS: Compared with marker admissions, an increased PCP density in an area was associated with a higher probability of black admissions than white admissions for referral-sensitive procedures. CONCLUSIONS: Our analysis suggests that the supply of primary care may be important for admissions for referral-sensitive procedures. Nonwhites, especially blacks, may have greater access to these procedures through increased PCP supply. Increased PCP density may significantly narrow the racial disparity in specialty referrals and improve the referral process for these procedures for nonwhites.

Adult↗

PubMed2000

Characterization of derivatives of the high-molecular-mass penicillin-binding protein (PBP) 1 of Mycobacterium leprae.

Mycobacterium leprae has two high-molecular-mass multimodular penicillin-binding proteins (PBPs) of class A, termed PBP1 and PBP1* [Lepage, Dubois, Ghosh, Joris, Mahapatra, Kundu, Basu, Chakrabarti, Cole, Nguyen-Disteche and Ghuysen (1997) J. Bacteriol. 179, 4627-4630]. PBP1-Xaa-beta-lactamase fusions generated periplasmic beta-lactamase activity when Xaa (the amino acid of PBP1 at the fusion junction) was residue 314, 363, 407, 450 or 480. Truncation of the N-terminal part of the protein up to residue Leu-147 generated a penicillin-binding polypeptide which could still associate with the plasma membrane, whereas [DeltaM1-R314]PBP1 (PBP1 lacking residues Met-1 to Arg-314) failed to associate with the membrane, suggesting that the region between residues Leu-147 and Arg-314 harbours an additional plasma membrane association site for PBP1. Truncation of the C-terminus up to 42 residues downstream of the KTG (Lys-Thr-Gly) motif also generated a polypeptide that retained penicillin-binding activity. [DeltaM1-R314]PBP1 could be extracted from inclusion bodies and refolded under appropriate conditions to give a form capable of binding penicillin with the same efficiency as full-length PBP1. This is, to the best of our knowledge, the first report of a soluble derivative of a penicillin-resistant high-molecular-mass PBP of class A that is capable of binding penicillin. A chimaeric PBP in which the penicillin-binding (PB) module of PBP1 was fused at its N-terminal end with the non-penicillin-binding (n-PB) module of PBP1* retained pencillin-binding activity similar to that of PBP1, corroborating the finding that the n-PB module of PBP1 is dispensable for its penicillin-binding activity.

Bacterial Proteins↗

PubMed2000

Out-of-area travel from rural and urban counties: a study of ambulatory care sensitive hospitalizations for New York State residents.

Rural patients who are admitted to hospitals outside their residence county or who travel great distances for hospitalization deprive local rural hospitals of revenue. To provide more information about such rural residents, we studied their characteristics compared to those admitted in the same county. Characteristics studied included illness severity, demographics and county resources. To validate the findings and to provide a different analytic approach, characteristics of residents who travel long distances for admission were also studied. We studied admissions for ambulatory care sensitive conditions, as they might be most responsive to policy changes such as increasing recruitment of local primary-care physicians. Hospital discharges during 1994 for 248,656 New York State residents were studied. We constructed multivariate models using logistic regression and ordinary least squares methods. The models were applied to residents in three types of geographic location along an urban-rural continuum. Outside admissions were associated with younger age, higher illness severity and fewer county hospital resources. Same county admissions were associated with nonwhite race, and lack of insurance. Surprisingly, in rural counties, outside admissions were directly associated with increased primary-care providers. Results from the distance model generally supported findings from the outside admission model.

Ambulatory Care↗

PubMed1999

Mutations in the essential spindle checkpoint gene bub1 cause chromosome missegregation and fail to block apoptosis in Drosophila.

We have characterized the Drosophila mitotic checkpoint control protein Bub1 and obtained mutations in the bub1 gene. Drosophila Bub1 localizes strongly to the centromere/kinetochore of mitotic and meiotic chromosomes that have not yet reached the metaphase plate. Animals homozygous for P-element-induced, near-null mutations of bub1 die during late larval/pupal stages due to severe mitotic abnormalities indicative of a bypass of checkpoint function. These abnormalities include accelerated exit from metaphase and chromosome missegregation and fragmentation. Chromosome fragmentation possibly leads to the significantly elevated levels of apoptosis seen in mutants. We have also investigated the relationship between Bub1 and other kinetochore components. We show that Bub1 kinase activity is not required for phosphorylation of 3F3/2 epitopes at prophase/prometaphase, but is needed for 3F3/2 dephosphorylation at metaphase. Neither 3F3/2 dephosphorylation nor loss of Bub1 from the kinetochore is a prerequisite for anaphase entry. Bub1's localization to the kinetochore does not depend on the products of the genes zw10, rod, polo, or fizzy, indicating that the kinetochore is constructed from several independent subassemblies.

Animals↗

PubMed1999

Mapping of a palmitoylatable band 3-binding domain of human erythrocyte membrane protein 4.2.

Evidence accumulated over the years suggests that human erythrocyte membrane protein 4.2 is one of the proteins involved in strengthening the cytoskeleton-membrane interactions in the red blood cell. Deficiency of protein 4.2 is linked with a variety of hereditary haemolytic anaemia. However, the interactions of protein 4.2 with other proteins of the erythrocyte membrane remain poorly understood. The major membrane-binding site for protein 4.2 resides on the cytoplasmic domain of band 3 (CDB3). In order to carry out an initial characterization of its interaction with the CDB3, protein 4. 2 was subjected to proteolytic cleavage and gel renaturation assay, and the 23-kDa N-terminal domain was found to interact with band 3. This domain contained two putative palmitoylatable cysteine residues, of which cysteine 203 was identified as the palmitoylatable cysteine. Recombinant glutathione S-transferase-fusion peptides derived from this domain were characterized with respect to their ability to interact with the CDB3. Whereas these studies do not rule out the involvement of other subsites on protein 4.2 in interaction with the CDB3, the evidence suggests that the region encompassing amino acid residues 187-211 is one of the domains critical for the protein 4.2-CDB3 interaction. This is also the first demonstration that palmitoylation serves as a positive modulator of this interaction.

Amino Acid Sequence↗

PubMed1998

Viral characteristics of human papillomavirus infection and antioxidant levels as risk factors for cervical dysplasia.

Genital human papillomavirus (HPV) infection is the major causal factor of cervical intraepithelial neoplasia (CIN). The potential role of nutrition as an additional, independent risk factor for CIN has not been appropriately addressed in the context of HPV. This case-control study evaluated the etiologic role of HPV in terms of viral type and load and examined the association between CIN and plasma levels of micronutrients adjusting for HPV. Cases (n = 378) with histo-pathologically confirmed CIN and controls (n = 366) with no history of abnormal Pap smears were recruited from colposcopy and gynecology clinics, respectively. Risk of CIN was significantly increased among women who were infected with multiple HPV types (odds ratio [OR] = 21.06), a high viral load (OR = 13.08) and HPV 16 (OR = 62.49). After adjusting for HPV positivity and demographic factors, there was an inverse correlation between plasma alpha-tocopherol and risk of CIN (OR = 0.15). Plasma ascorbic acid was protective at a high level of > or = 0.803 mg/dl (OR = 0.46). CIN was not associated with plasma retinol and beta-carotene levels. The effect of genital HPV infection on CIN development is highly influenced by oncogenic viral type and high viral load. Vitamins C and E may play an independent protective role in development of CIN that needs to be confirmed in prospective studies.

Adult↗

PubMed1998

HPV 16 and cigarette smoking as risk factors for high-grade cervical intra-epithelial neoplasia.

Although genital human papillomavirus (HPV) infection is well established as the etiologic agent for cervical intraepithelial neoplasia (CIN), little is known about the cofactors involved in the development of high-grade lesions or the progression of low-grade to high-grade lesions. In our study of HPV-infected women with CIN (163 CIN I, 51 CIN II and 44 CIN III), women with CIN II or III were compared with those with CIN I for risk factors associated with high-grade lesions. After controlling for age, education, ethnicity and frequency of Pap smear screening, infection with HPV 16, but not high viral load or infection with multiple types, was associated with high-grade lesions (OR for CIN II = 11.96, OR for CIN III = 23.74). Risk of CIN III, but not CIN II, increased with number of cigarettes smoked per day (ORs = 1.49 and 3.35 for < or = 10 and > 10 cigarettes per day, respectively) and decreased with frequency of condom use during sex (ORs = 0.60 and 0.32 for women who used condoms occasionally/sometimes and most/all of the time, respectively). There were no associations between high-grade lesions and plasma levels of micronutrients (retinol, beta-carotene, alpha-tocopherol and reduced ascorbic acid). Our results indicate that infection with HPV 16 is associated with high-grade lesions. Additional cofactors, such as cigarette smoking, may be required as a carcinogen to advance HPV-infected cells toward neoplastic progression.

Adult↗

PubMed1998

Depletion of a Drosophila homolog of yeast Sup35p disrupts spindle assembly, chromosome segregation, and cytokinesis during male meiosis.

In the course of a genetic screen for male-sterile mutations in Drosophila affecting chromosome segregation during the meiotic divisions in spermatocytes, we identified the mutation dsup35(63D). Examination of mutant testes showed that chromosome misbehavior was a consequence of major disruptions in meiotic spindle assembly. These perturbations included problems in aster formation, separation, and migration around the nuclear envelope; aberrations in spindle organization and integrity; and disappearance of the ana/telophase central spindle, which in turn disrupts cytokinesis. The dsup35(63D) mutation is caused by a P element insertion that affects, specifically in the testis, the expression of a gene (dsup35) encoding the Drosophila homolog of the yeast Sup35p and Xenopus eRF3 proteins. These proteins are involved in the termination of polypeptide synthesis on ribosomes, but previous studies have suggested that Sup35p and closely related proteins of the same family also interact directly with microtubules. An affinity-purified antibody directed against the product of the dsup35 gene was prepared; interestingly, this antibody specifically labels primary spermatocytes in one or two discrete foci of unknown structure within the nucleoplasm. We discuss how depletion of the dsup35 gene product in spermatocytes might lead to the global disruptions in meiotic spindle assembly seen in mutant spermatocytes.

Amino Acid Sequence↗

PubMed1998

Localization of the Drosophila checkpoint control protein Bub3 to the kinetochore requires Bub1 but not Zw10 or Rod.

We report here the isolation and molecular characterization of the Drosophila homolog of the mitotic checkpoint control protein Bub3. The Drosophila Bub3 protein is associated with the centromere/kinetochore of chromosomes in larval neuroblasts whose spindle assembly checkpoints have been activated by incubation with the microtubule-depolymerizing agent colchicine. Drosophila Bub3 is also found at the kinetochore regions in mitotic larval neuroblasts and in meiotic primary and secondary spermatocytes, with the strong signal seen during prophase and prometaphase becoming increasingly weaker after the chromosomes have aligned at the metaphase plate. We further show that the localization of Bub3 to the kinetochore is disrupted by mutations in the gene encoding the Drosophila homolog of the spindle assembly checkpoint protein Bub1. Combined with recent findings showing that the kinetochore localization of Bub1 conversely depends upon Bub3, these results support the hypothesis that the spindle assembly checkpoint proteins exist as a multiprotein complex recruited as a unit to the kinetochore. In contrast, we demonstrate that the kinetochore constituents Zw10 and Rod are not needed for the binding of Bub3 to the kinetochore. This suggests that the kinetochore is assembled in at least two relatively independent pathways.

Amino Acid Sequence↗

PubMed1998

The Des-1 protein, required for central spindle assembly and cytokinesis, is associated with mitochondria along the meiotic spindle apparatus and with the contractile ring during male meiosis in Drosophila melanogaster.

Spermatogenesis in Drosophila melanogaster serves as an excellent model system for the isolation and analysis of genes required in the control of chromosome segregation and cytokinesis. We report here the isolation and molecular characterization of a novel P-element induced allele of the des-1 gene, which leads to male sterility as a consequence of the failure of central spindle assembly in meiotic spermatocytes and the formation of aberrant meiotic end products characteristic of cytokinesis failure. We have raised affinity-purified antibodies against a Des-1 fusion protein, and localized the Des-1 protein in Drosophila spermatocytes. We show that the Des- protein is colocalized with mitochondria throughout male meiosis, becoming intimately associated with mitochondria along the spindle apparatus during anaphase and telophase, and with the Nebenkern, or mitochondrial derivative, of the meiotic end products. In addition, a significant association of Des-1 with the contractile ring is observed during anaphase and telophase of meiosis. These observations, together with the presence of six potential transmembrane domains in the Des-1 protein, raise the possibility that Des-1 may act as part of an anchoring mechanism that links membrane-bounded cellular compartments to components of the cytoskeleton.

Animals↗

PubMed1998

Plasma concentrations of micronutrients during a nine-month clinical trial of beta-carotene in women with precursor cervical cancer lesions.

The effects of oral supplementation of a 30-mg dose of beta-carotene on the plasma levels of carotenoids, tocopherols, and retinol were studied sequentially in 69 patients participating in a nine-month randomized placebo controlled trial conducted to examine efficacy of beta-carotene to induce regression of cervical intraepithelial neoplasia. At each visit (baseline and 1.5, 3, 6, 9, 10.5, and 15 mo), blood samples were collected and the levels of six micronutrients were determined by high-performance liquid chromatography. No limitations or changes were introduced in each participant's dietary habits. Cervico-vaginal lavage samples were also obtained at the same visit and assayed for the presence of human papillomavirus DNA by Southern blot hybridization and polymerase chain reaction. In the supplemented group, mean plasma beta-carotene levels were significantly higher (p = 0.0001) than baseline and remained markedly elevated for 15 months. In the longitudinal analysis of the placebo group, there were no variations among individual mean plasma levels of beta-carotene, alpha-carotene, lycopene, retinol, gamma-tocopherol, or alpha-tocopherol, suggesting absence of seasonal or dietary changes. In the placebo group, cigarette smoking and steroid contraceptive use were significantly associated with low levels of plasma beta-carotene (p = 0.05 and p = 0.012, respectively). However, in contrast, in the beta-carotene-supplemented group, steroid contraceptive use had no influence on the plasma beta-carotene levels. An additional noteworthy finding was that beta-carotene supplementation did not reverse the depletion effect in smokers. There was no association between the plasma levels of these six micronutrients in women with cervical intraepithelial neoplasia and persistent human papillomavirus infection status in the placebo or the supplemented groups. Functional sequential nutrient interactions with each other or with other essential micronutrients and possible long-term toxicity need to be addressed in clinical trials.

Adult↗

PubMed1997

Purification and biochemical characterization of a protein-palmitoyl acyltransferase from human erythrocytes.

Protein palmitoylation involves the post-translational attachment of palmitate in thioester linkage to cysteine residues of proteins. The labile nature of the thioester linkage makes possible the palmitoylation-depalmitoylation cycles that have emerged in recent times as additions to the repertoire of cellular control mechanisms. However, detailed understanding of these cycles has been limited by the lack of knowledge of the transferases and thioesterases likely to be involved. Here, we describe the purification of a protein-palmitoyl acyltransferase (PAT) from human erythrocytes. PAT behaved as a peripheral membrane protein and catalyzed the attachment of palmitate in thioester linkage to the beta-subunit of spectrin. On SDS-polyacrylamide gel electrophoresis, PAT appeared as a 70-kDa polypeptide. Antibody against this polypeptide could immunodeplete PAT activity from the crude extract, confirming the assignment of the 70-kDa polypeptide as PAT. PAT-mediated spectrin palmitoylation could be inhibited by nonradioactive palmitoyl-, myristoyl-, or stearoyl-CoA. The apparent Km for palmitoyl-CoA was 16 microM.

Acylation↗

PubMed1997

Effects of beta-carotene and other factors on outcome of cervical dysplasia and human papillomavirus infection.

Women with histopathologically confirmed cervical intraepithelial neoplasia (CIN) were followed at 3-month intervals in a randomized double-blinded trial to evaluate the efficacy of beta-carotene to cause regression of CIN. Questionnaire data, plasma levels of micronutrients, and a cervicovaginal lavage for human papillomavirus (HPV) detection were obtained at each visit, and an endpoint biopsy was performed at 9 months. Sixty-nine subjects had a biopsy endpoint evaluation; 9 of 39 (23%) subjects in the beta-carotene group versus 14 of 30 (47%) in the placebo group had regression of CIN (P = 0.039). Independent risk factors for persistent CIN at 9 months included type-specific persistent HPV infection (OR = 11.38, P = 0.006) and continual HPV infection with a high viral load (OR = 14.25, P = 0.007) at baseline and 9 months, an initial diagnosis of > or =CIN II (OR = 6.74, P = 0.016), and older age (OR for > or =25 years = 4.10, P = 0.072). After controlling for these factors, the beta-carotene and placebo groups did not differ in risk for having CIN at 9 months (OR = 1.53, P = 0.550). Resolution of baseline HPV infection was significantly correlated with non-high-risk HPV types (RR = 2.94, P = 0.015), age <25 years (RR = 2.62, P = 0.014), and douching after sexual intercourse (RR = 3.02, P = 0.012), but not with randomization group. Our data indicate that a large proportion of mild CIN lesions regress; age and HPV infection play an important role in the natural course of CIN; and repeated HPV testing may have a value in distinguishing women who need aggressive treatment for CIN versus those who do not. Supplementation of beta-carotene does not appear to have a detectable benefit in treatment of CIN.

Adult↗