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Biomedical subjects

A Das

Publications and source records attributed to A Das.

At least 109 records · Page 6Linked to original sources
PubMed2000

Fetal fibronectin and bacterial vaginosis in smokers and nonsmokers. The National Institute of Child Health and Human Development Maternal- Fetal Medicine Units Network.

To determine whether maternal smoking influences the relationship between bacterial vaginosis and fetal fibronectin, the presence of cervical or vaginal fetal fibronectin, the presence of bacterial vaginosis, and smoking status were determined for 2899 women at 24 weeks' gestation. Fetal fibronectin was more common among women with bacterial vaginosis, but maternal smoking did not increase the likelihood that women with bacterial vaginosis would have fetal fibronectin detected. A previously reported impact of maternal smoking status on the relationship between bacterial vaginosis and fetal fibronectin thus was not confirmed.

Cervix Uteri↗
PubMed2000

Meningiomas in Singapore: demographic and biological characteristics.

We sought to determine the relative incidence of meningiomas compared to other central nervous system tumours in an Asian surgical series, as well as the demographic and biological characteristics of these meningiomas. A review of 655 consecutive cases of central nervous system tumours from 583 patients representing the last five years admissions to one hospital in Singapore was undertaken. A total of 33 malignant/atypical tumours from 19 patients and 196 benign meningiomas from 187 patients were identified. Twenty malignant/atypical and 20 benign tumours were selected at random and subjected to histochemical and immunohistochemical analysis using antibodies directed against p53, bax and 3'-DNA hydroxy groups (TUNEL). Meningiomas comprised some 35.2% of all central nervous system tumours with malignant/atypical meningiomas representing 9.2% of meningiomas. Histochemically, necrosis was the predominant finding. However, peri-necrotic areas displayed p53 positivity in 10% of cases and bax positivity in 25% of cases. Apoptotic cells were detected in the peri-necrotic areas in 90% of benign and 75% of malignant/atypical meningiomas. Meningiomas represent the predominant form of central nervous system tumour in the Singaporean population, and aberration of p53 expression is not associated with tumour formation or progression. There was a slight but non-significant reduction in apoptosis in the progression from benign to malignant meningioma, suggesting that in contrast to many other tumour types disruption of cellular apoptosis is not a predominant driving force in Asian meningioma tumourigenesis.

Apoptosis↗
PubMed2000

Paecilomyces variotii in a pediatric patient with lung transplantation.

Aspergillus has been noted to be the most common species of filamentous fungus isolated from the airways of lung transplantation (Tx) patients. In general, the bronchi are colonized asymptomatically with Aspergillus but this places such a patient population at greater risk of invasive infection. Other filamentous fungal species may also assume importance in this patient population. Here we report the post-transplant isolation of Paecilomyces variotii from the airways of a pediatric patient with cystic fibrosis (CF) who underwent bilateral living-donor lobar lung Tx. This is the first report of isolation of P. variotii in the pediatric lung Tx population. The isolation of filamentous fungi, such as Paecilomyces, with variable in vitro susceptibility to currently available antifungal agents further complicates the approach to post-transplant antifungal therapy in patients with lung Tx.

Bronchi↗
PubMed2000

The structure of the transcriptional antiterminator NusB from Escherichia coli.

We have determined the solution structure of NusB, a transcription antitermination protein from Escherichia coli. The structure reveals a novel, all alpha-helical protein fold. NusB mutations that cause a loss of function (NusB5) or alter specificity for RNA targets (NusB101) are localized to surface residues and likely affect RNA-protein or protein-protein interactions. Residues that are highly conserved among homologs stabilize the protein core. The solution structure of E. coli NusB presented here resembles that of Mycobacterium tuberculosis NusB determined by X-ray diffraction, but differs substantially from a solution structure of E. coli NusB reported earlier.

Amino Acid Sequence↗
PubMed2000

Subcellular localization of the Agrobacterium tumefaciens T-DNA transport pore proteins: VirB8 is essential for the assembly of the transport pore.

Agrobacterium tumefaciens transforms plants by transferring DNA to the plant cell nucleus. The VirB membrane proteins are postulated to form a pore for the transport of the DNA across the bacterial membranes. Immunofluorescence and immunoelectron microscopy were used to study the transport pore complex. Three likely components of the transport pore, VirB8, VirB9 and VirB10, localized primarily to the inner membrane, outer membrane and periplasm respectively. A significant amount of VirB10 was also found associated with the outer membrane. When expressed alone VirB9 and VirB10 were randomly distributed along the cell membrane. Subcellular location of both proteins changed dramatically in the presence of the other VirB proteins. Both proteins localized to fewer sites and most of the gold particles representing protein molecules were found in clusters suggesting that the two proteins are in a protein complex. VirB8, on the other hand, localized to clusters even in the absence of the other VirB proteins. To investigate the role of VirB8 in the formation of VirB9 and VirB10 protein complexes, we studied the effect of deletion of virB8 on the subcellular location of VirB9 and VirB10. In a virB8 deletion mutant both proteins were distributed randomly on the cell membrane indicating that VirB8 is essential for complex assembly.

Agrobacterium tumefaciens↗
PubMed2000

Efficacy of a combination of FCHG49 glucosamine hydrochloride, TRH122 low molecular weight sodium chondroitin sulfate and manganese ascorbate in the management of knee osteoarthritis.

OBJECTIVES: The objective of this study was to evaluate the oral combination of glucosamine HCl, sodium chondroitin sulfate and manganese ascorbate for the treatment of osteoarthritis (OA) of the knee. DESIGN: A randomized placebo-controlled study design was implemented. We recruited 93 patients with OA of the knee from a single center. The intervention group received 1000 mg FCHG49 glucosamine HCl, 800 mg TRH122 low molecular weight sodium chondroitin sulfate and 152 mg manganese ascorbate twice daily (Cosamin DS). Patients were evaluated initially and then every 2 months for 6 months. The primary outcome was the Lesquene Index of severity of osteoarthritis of the knee (ISK). RESULTS: Patients with radiographically mild or moderate OA (N=72) in the intervention group showed significant improvement in the ISK at 4 and 6 months (P=0.003 and P=0.04, respectively). The response rate to the medication was 52% vs a 28% response rate to placebo. Patients with radiographically severe osteoarthritis (N=21) did not show significant improvements in the ISK. There was a 17% incidence of adverse events in the intervention group and 19% in the placebo group. CONCLUSIONS: The studied combination of glucosamine HCl, sodium chondroitin sulfate and manganese ascorbate was found to be effective for the treatment of radiographically mild to moderate OA of the knee as measured by the ISK. This is the first U.S. study of these agents.

Aged↗
PubMed2000

Preterm prediction study: is socioeconomic status a risk factor for bacterial vaginosis in Black or in White women?

Bacterial vaginosis (BV), an important risk factor for preterm birth, is a more common infection in Black compared with White pregnant women. Because Black women in the United States are more likely to have lower measures of socioeconomic status (SES), this study examined the hypothesis that BV is associated with low SES. The project evaluated data from the Preterm Prediction Study of 2,929 women prospectively followed during their pregnancies. The women, who were screened for BV at 24 and 28 weeks of gestation, underwent a structured interview to evaluate demographic factors, SES, home and work environment, drug or alcohol use, and prior medical history. Black women in the study had many measures of lower SES compared with the White women, and reported less use of tobacco, alcohol and drugs. In neither the Black nor White women was an association found between BV and measures of SES (with the sole exception of "absence of a home telephone"). Most measures of SES do not explain the difference in rates of BV in Black and in White pregnant women.

Black or African American↗
PubMed2000

The preterm prediction study: granulocyte colony-stimulating factor and spontaneous preterm birth. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

OBJECTIVE: Granulocyte colony-stimulating factor is elevated in the amniotic fluid and plasma of women with chorioamnionitis and active preterm labor. We investigated the relationship between plasma granulocyte colony-stimulating factor and subsequent spontaneous preterm birth in pregnant women without symptoms. STUDY DESIGN: We performed a nested case-control study involving 194 women who had a singleton spontaneous preterm birth and 194 matched term control subjects from the patient pool (n = 2929) enrolled in the Preterm Prediction Study. Plasma collected at 24 and 28 weeks' gestation was analyzed for granulocyte colony-stimulating factor, and the results were compared with subsequent spontaneous preterm birth. RESULTS: Compared with term control subjects, women who were delivered of their infants spontaneously at <28 weeks' gestation had increased mean granulocyte colony-stimulating factor values at 24 weeks' gestation (84.7 +/- 38.4 vs 67.7 +/- 28.6 pg/mL; P =.049), and women who were delivered of their infants at <32 weeks' gestation had increased mean plasma granulocyte colony-stimulating factor values at 28 weeks' gestation (80.4 +/- 24.1 vs 55.9 +/- 16.5 pg/mL; P =. 001). At 24 weeks' gestation a granulocyte colony-stimulating factor value >75th percentile in control subjects (approximately 80 pg/mL) was found in 48.9% (23/47) of all women delivered of their infants at <32 weeks' gestation versus 14.9% (7/47) of the term control subjects (adjusted odds ratio, 6.2; 95% confidence interval, 1.8-20. 8). At 28 weeks' gestation a granulocyte colony-stimulating factor value >75th percentile was found in 36.8% (7/19) of women delivered of their infants at <32 weeks' gestation versus 5.3% (1/19) of term control subjects (adjusted odds ratio, 25.7; 95% confidence interval, 1.5-470.4). When measured at 24 or 28 weeks' gestation, granulocyte colony-stimulating factor did not predict spontaneous preterm birth at 32 to 34 weeks' gestation or at 35 to 36 weeks' gestation. CONCLUSION: In pregnant women without symptoms at 24 and 28 weeks' gestation, elevated plasma granulocyte colony-stimulating factor levels are associated with subsequent early (<32 weeks' gestation) spontaneous preterm birth, especially within the next 4 weeks, but not with late spontaneous preterm birth. These data provide further evidence that early spontaneous preterm birth is associated with an inflammatory process that is identifiable by the presence of a cytokine in maternal plasma several weeks before the early spontaneous preterm birth; however, later spontaneous preterm birth is not associated with this process.

Adolescent↗
PubMed2000

The preterm prediction study: cervical lactoferrin concentration, other markers of lower genital tract infection, and preterm birth. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

OBJECTIVE: This study was undertaken to determine the relationship among cervical lactoferrin concentration, other cervical markers potentially related to infection, and spontaneous preterm birth. STUDY DESIGN: Cervical lactoferrin concentrations obtained at 22 to 24 weeks' gestation among 121 women who had a spontaneous preterm birth <35 weeks' gestation were compared with cervical lactoferrin concentrations among 121 women matched for race, parity, and center who were delivered at >/=37 weeks' gestation. Results were compared against levels of cervical interleukin 6, fetal fibronectin, and sialidase, against cervical length according to ultrasonography, and according to the bacterial vaginosis Gram stain score. RESULTS: Cervical lactoferrin concentrations ranged from not measurable (19% of the concentrations were below the threshold for this assay) to a titer of >/=1:64. There was no significant difference in the overall distributions of lactoferrin concentrations between the case patients and control subjects (P =.18). Only when the highest titers of lactoferrin were considered were there more women in the spontaneous preterm birth group (6/121 vs 0/121; P =.03). According to Spearman correlation analyses the cervical lactoferrin concentrations were strongly related to interleukin 6 concentration (r =.51; P =.0001), sialidase activity (r =.38; P =.0001), and bacterial vaginosis (r =.38; P =.0001), were weakly related to fetal fibronectin (r =. 16; P =.01), and were not related to cervical length. With the 90th percentile (a dilution of 1:32) used as a cutoff to establish a dichotomous variable, lactoferrin concentration had the following odds ratios and 95% confidence intervals for associations with other potential markers of infection: bacterial vaginosis odds ratio, 4.8 (95% confidence interval, 2.2-10.3); interleukin 6 concentration odds ratio, 2.8 (95% confidence interval, 1.2-6.5); sialidase activity odds ratio, 5. 5 (95% confidence interval, 2.2-13.7); fetal fibronectin concentration odds ratio, 0.6 (95% confidence interval, 0.2-2.0); chlamydiosis odds ratio, 2.3 (95% confidence interval, 0.8-6.9); and short cervix odds ratio, 0.5 (95% confidence interval, 0.2-1.4). CONCLUSIONS: Lactoferrin found in the cervix correlated well with other markers of lower genital tract infection. High lactoferrin levels were associated with spontaneous preterm birth but had a very low predictive sensitivity.

Bacterial Infections↗
PubMed2000

The Preterm Prediction Study: sequential cervical length and fetal fibronectin testing for the prediction of spontaneous preterm birth. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

OBJECTIVES: This study was undertaken to further elucidate the pathogenesis of preterm birth by means of traditional risk factors and new markers for preterm birth derived from the Preterm Prediction Study. STUDY DESIGN: A total of 3076 women (2929 with singleton gestations and 147 with twin pregnancies) were categorized according to the presence of risk factors including black race, low body mass index, the presence of bacterial vaginosis, and previous preterm birth. At 24 and 28 weeks' gestation cervical length was measured and categorized as short (</=25 mm) or normal (>25 mm). Vaginal and cervical fetal fibronectin concentrations were measured at 24, 26, 28, and 30 weeks' gestation and results were categorized as positive (>/=50 ng/mL) or negative (<50 ng/mL). RESULTS: At 24 to 26 weeks' gestation women with each of the risk factors were more likely to have positive fibronectin test results or to have a short cervix. Among women with negative fetal fibronectin results at 24 to 26 weeks' gestation those with a short cervix were more likely to have positive fetal fibronectin results at 28 to 30 weeks' gestation, and among those with normal cervical length those women who had positive fetal fibronectin results were more likely to have a short cervix at later evaluation. Most women who had positive fetal fibronectin results at 24 to 26 weeks' gestation had negative results at 28 to 30 weeks' gestation, whereas most but not all women who had a short cervix at 24 to 26 weeks' gestation still had a short cervix at 28 to 30 weeks' gestation. In each period women with both a positive fetal fibronectin result and a short cervix were at substantially increased risk of spontaneous preterm birth; women with either marker alone had intermediate and approximately equal risks of spontaneous preterm birth, and women without either marker had a low risk of spontaneous preterm birth. CONCLUSION: Regardless of other risk factors, a short cervix predicts a subsequent positive fetal fibronectin result, and a positive fetal fibronectin result predicts subsequent cervical shortening. These data do not support a single sequence of events leading to spontaneous preterm birth.

Biomarkers↗
PubMed2000

The Preterm Prediction Study: association of second-trimester genitourinary chlamydia infection with subsequent spontaneous preterm birth.

OBJECTIVE: This study was undertaken to determine the association between genitourinary tract infection with Chlamydia trachomatis and spontaneous preterm birth. STUDY DESIGN: Genitourinary tract infection with C trachomatis was determined with a ligase chain reaction assay of voided urine samples collected at 24 weeks' gestation (22 weeks' to 24 weeks 6 days' gestation) and 28 weeks' gestation (27 weeks' to 28 weeks 6 days' gestation). Case patients (spontaneous preterm birth at <37 weeks' gestation; n = 190) and control subjects (delivery at >/=37 weeks' gestation, matched for race, parity, and center; n = 190) were selected from 2929 women enrolled in the Preterm Prediction Study of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. RESULTS: Genitourinary C trachomatis infection (11% overall) was significantly more common among the case patients than among the control subjects at 24 weeks' gestation (15.8% vs 6.3%; P =.003) but not at 28 weeks' gestation (12.6% vs 10.9%; P =.61). Women with chlamydia infection were more likely to have bacterial vaginosis (57.1% vs 32.9%; P =.002) and a short cervical length (</=25 mm; 33.0% vs 17.9%; P =.02) but not a body mass index <19.8 kg/m(2) (35.0% vs 23.9%; P =.17) or a positive fetal fibronectin test result (7.1% vs 9.5%; P =.62). After adjustment for risk factors for spontaneous preterm birth, women with C trachomatis infection at 24 weeks' gestation were 2 times as likely as uninfected women to have a spontaneous preterm birth at <37 weeks' gestation (odds ratio, 2.2; 95% confidence interval, 1.03-4.78) and 3 times as likely to have a spontaneous preterm birth at <35 weeks' gestation (odds ratio, 3.2; 95% confidence interval, 1.08-9.57). CONCLUSION: Genitourinary C trachomatis infection at 24 weeks' gestation was associated with a 2-fold to 3-fold increased risk of subsequent spontaneous preterm birth.

Adolescent↗
PubMed2000

The Preterm Prediction Study: prediction of preterm premature rupture of membranes through clinical findings and ancillary testing. The National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

OBJECTIVE: Our objective was to determine the relative importance of demographic characteristics, clinical risk factors, and ancillary screening tests in the prediction of preterm birth as a result of premature rupture of membranes. STUDY DESIGN: A total of 2929 women were evaluated in 10 centers at 23 to 24 weeks' gestation. Demographic and clinical characteristics were ascertained. Cervicovaginal fetal fibronectin and bacterial vaginosis were evaluated. Cervical length was measured by vaginal ultrasonography. Patients were evaluated for spontaneous preterm birth caused by preterm premature rupture of membranes at <37 and <35 weeks' gestation. Multivariate analyses were performed separately for nulliparous women and multiparous women. RESULTS: Premature rupture of membranes at <37 weeks' gestation complicated 4.5% of pregnancies, accounting for 32.6% of preterm births. Univariate analysis revealed low body mass index, pulmonary disease, contractions within 2 weeks, short cervix (</=25 mm), positive results of fetal fibronectin screening, bacterial vaginosis, and a previous preterm birth caused by premature rupture of membranes (in multiparous women) to be significantly associated with preterm birth caused by premature rupture of membranes in the current gestation. Short cervix, previous preterm birth caused by premature rupture of membranes in multiparous women, and presence of fetal fibronectin were the strongest predictors for both preterm birth caused by premature rupture of membranes at <37 and <35 weeks' gestation. Women with positive fetal fibronectin screening results and a short cervix had greater risks both of preterm birth caused by premature rupture of membranes at <37 weeks' gestation (relative risk, 4.9) and of preterm birth caused by premature rupture of membranes at <35 weeks' gestation (relative risk, 13.5) than did those without these risk factors. Multiparous women with all three risk factors had a 31. 3-fold increased risk of preterm birth caused by premature rupture of membranes at <35 weeks' gestation. CONCLUSION: The combination of short cervical length, previous preterm birth caused by preterm premature rupture of membranes, and positive fetal fibronectin screening results was highly associated with preterm delivery caused by preterm premature rupture of membranes in the current gestation.

Cervix Uteri↗
PubMed2000

Histologic effects of holmium:YAG laser resection versus transurethral resection of the prostate.

BACKGROUND AND PURPOSE: Holmium laser resection (HoLRP) is an effective surgical alternative to transurethral resection of the prostate (TURP). We investigated whether an adequate histologic diagnosis could be made from HoLRP tissue specimens. PATIENTS AND METHODS: A series of 120 patients were randomized to TURP (N = 59) or HoLRP (N = 61). Each histologic specimen was reviewed by a single pathologist, who was blinded to the treatment. Weight of tissue, histologic diagnosis, and degree of thermal artifact were assessed. Thermal damage was graded as follows: 1 = no significant thermal injury; 2 = <25% of the tissue damaged (minimal); 3 = 25% to 80% of the tissue damaged (moderate); and 4 = >80% of the tissue damaged, with loss of prostatic architecture (extensive). RESULTS: The mean weight of the TURP and HoLRP specimens was 15.6 g and 9.6 g, respectively. The mean grade of thermal artifact for the TURP group was 1.8 and for the HoLRP group 2.6. Of the HoLRP specimens, 56 (92%) were grade < or = 3. Of the entire series of 120 specimens, 5 contained malignant tissue, all of which were from the TURP group. Four of these specimens were adenocarcinoma of the prostate, whereas the other was a transitional-cell carcinoma. Of the four specimens that contained prostate cancer, two were stage pTla tumors. CONCLUSIONS: Although identifiable prostatic architecture was maintained in the majority of histologic specimens from the HoLRP group, the tissue quality was inferior to that of TURP. There was significantly more vaporization and subsequent tissue loss with HoLRP, and the thermal damage to tissue was greater.

Adenocarcinoma↗
PubMed2000

Cost effectiveness analysis of different strategies of management of chronic hepatitis C infection in children.

BACKGROUND: Chronic hepatitis C virus infection in the pediatric patients is commonly encountered by clinicians, and although interferon-based therapy has been shown to be reasonably effective in children no formal economic analysis of such treatment strategies is available. METHODS: With a Markov cycle tree simulation model, a cost effectiveness analysis was done to compare interferon-based treatment strategies for chronic HCV infection in children with a strategy of no treatment in a cohort of 10-year-old otherwise healthy children. Clinical probabilities used in the model was obtained from available literature, and cost estimates were obtained from two teaching hospitals. Cost per patient, quality-adjusted life years gained in each strategy and incremental cost-effective ratio were the primary outcome measures compared. RESULTS: In the baseline analysis the treatment strategies dominated the strategy of no treatment. A 12-month treatment strategy was better than the 6-month treatment strategy. Combination therapy for 6 months with interferon and ribavirin was at least equally if not more effective than 12-month monotherapy. All treatment strategies decreased the number of patients developing decompensated cirrhosis, hepatocellular carcinoma and also number of orthotopic liver transplants in the lifetime of the model cohort. CONCLUSIONS: Interferon-based treatment strategies were more effective in terms of quality-adjusted life years saved and at the same time cheaper when compared with the strategy of no treatment. Combination therapy may be more cost-effective than interferon monotherapy, and clinical trials of combination therapy in pediatric patients are needed.

Child↗
PubMed2000

Asymmetric squares as standing waves in rayleigh-Benard convection

Possibility of thermal convection in the form of asymmetric squares in a thin layer of Boussinesq fluids of large lateral extension confined between stress-free and conducting flat boundaries is investigated numerically using a seven mode Lorenz-like model. For fluids with moderate and high Prandtl numbers (4<sigma<20) and in a narrow window of high Rayleigh numbers (12<R/R(c)<15), which depend on Prandtl number, the stationary rolls become unstable and asymmetric squares appear as standing waves at the onset of secondary instability. Asymmetric squares, two-dimensional rolls, and again asymmetric squares with their corners shifted by half a wavelength form a stable limit cycle. The oscillatory bifurcation is supercritical.

Journal Article↗
PubMed2000

The Agrobacterium T-DNA transport pore proteins VirB8, VirB9, and VirB10 interact with one another.

The VirB proteins of Agrobacterium tumefaciens form a transport pore to transfer DNA from bacteria to plants. The assembly of the transport pore will require interaction among the constituent proteins. The identification of proteins that interact with one another can provide clues to the assembly of the transport pore. We studied interaction among four putative transport pore proteins, VirB7, VirB8, VirB9 and VirB10. Using the yeast two-hybrid assay, we observed that VirB8, VirB9, and VirB10 interact with one another. In vitro studies using protein fusions demonstrated that VirB10 interacts with VirB9 and itself. These results suggest that the outer membrane VirB7-VirB9 complex interacts with the inner membrane proteins VirB8 and VirB10 for the assembly of the transport pore. Fusions that contain small, defined segments of the proteins were used to define the interaction domains of VirB8 and VirB9. All interaction domains of both proteins mapped to the N-terminal half of the proteins. Two separate domains at the N- and C-terminal ends of VirB9 are involved in its homotypic interaction, suggesting that VirB9 forms a higher oligomer. We observed that the alteration of serine at position 87 of VirB8 to leucine abolished its DNA transfer function. Studies on the interaction of the mutant protein with the other VirB proteins showed that the VirB8S87L mutant is defective in interaction with VirB9. The mutant, however, interacted efficiently with VirB8 and VirB10, suggesting that the VirB8-VirB9 interaction is essential for DNA transfer.

Bacterial Proteins↗