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Biomedical subjects

S Silver

Publications and source records attributed to S Silver.

At least 19 recordsLinked to original sources
PubMed2006

Nephrotic syndrome associated with chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

Chronic graft-versus-host disease (cGVHD) is the most common late complication of allogeneic hematopoietic cell transplantation (HCT) causing significant morbidity and mortality. The kidneys are not considered a target organ for cGVHD in humans, although animal models show renal damage. Renal involvement in patients with cGVHD, presenting as nephrotic syndrome (NS), has rarely been reported in patients who received allogeneic transplantation. Herein we describe, by far, the largest series of nine patients with NS associated with cGVHD, including two patients who received a reduced-intensity regimen. Pathological features of membranous nephropathy were the most common finding on renal biopsy. The clinical course of the NS was temporally associated with the classical features of cGVHD in all but one of the nine cases. The clinicopathologic features of NS in our series as well as reports in the literature demonstrate an immunopathologic process typical of antibody-mediated damage consistent with cGVHD. Treatment directed against antibody-mediated damage, such as anti-B-cell antibody may play an important role in ameliorating NS associated with cGVHD.

Adult↗
PubMed2004

West Nile virus encephalitis causing fatal CNS toxicity after hematopoietic stem cell transplantation.

We describe here a patient who died of progressive CNS deterioration following allogeneic stem cell transplant with West Nile virus as the sole pathogen on the cerebrospinal fluid and brain tissue analysis. A 50-year-old male with Philadelphia chromosome-positive acute lymphocytic leukemia (ALL) underwent allogeneic PBSCT from his HLA identical sister. After engraftment, the patient developed fever with progressive and ultimately fatal neurological deterioration. Imaging studies of the brain including CT and MRI scans were remarkable for mild low attenuation lesions of the white matter. CSF analysis was negative for neoplastic cells, bacteria, AFB, CMV, HSV, fungal infections and leukemic relapse. However, serological analysis of both the serum and CSF was positive for West Nile virus-specific IgM antibodies. At autopsy, West Nile virus PCR and cultures were positive in the mid-brain tissue. Electron micrographs showed evidence of viral particles. Given the recent increase in the spread of West Nile virus infections and the increased susceptibility of BMT patients to infectious complications, West Nile virus encephalitis should be considered in patients undergoing transplantation.

Autopsy↗
PubMed2004

Tacrolimus as monotherapy or combined with minidose methotrexate for graft-versus-host disease prophylaxis after allogeneic peripheral blood stem cell transplantation: long-term outcomes.

We report long-term outcomes for allogeneic peripheral blood stem cell (PBSC) recipients, evaluating cumulative incidence (CI) of acute and chronic graft-versus-host disease (GVHD), after use of tacrolimus with or without minidose methotrexate for GVHD prophylaxis. From April 1996 to April 1998, 97 adults underwent allogeneic PBSC transplantation. The first 49 received tacrolimus monotherapy as GVHD prophylaxis and the subsequent 48 received combination therapy. The median follow-up for survivors was 67 months. Compared to combination therapy, tacrolimus monotherapy resulted in enhanced neutrophil engraftment, shortened hospitalization, comparable rates of GVHD, and equivalent 100-day survival. The CI of grades II-IV acute GVHD was 35% with tacrolimus and 23% with the combination (P=0.19). The CI of III-IV GVHD was 22% for tacrolimus and 19% for the combination. CI of chronic GVHD was similar between the two groups (P=0.5). Patients with good-risk disease had superior overall survival (OS) when compared to those with poor-risk features (P<0.001). Within the good-risk disease category, patients receiving methotrexate had a trend towards improved OS (P=0.07). Multivariate analysis indicated good-risk disease status and methotrexate were independently associated with improved OS, progression-free survival (PFS), and relapse. In addition, patients developing chronic GVHD had a significantly reduced risk of relapse and improved PFS.

Acute Disease↗
PubMed2001

Clinical protocol. Purging of autologous stem cell sources with bcl-x(s) adenovirus for women undergoing high-dose chemotherapy for stage IV breast carcinoma.

High-dose chemotherapy (HDCT) and autologous bone marrow transplantation (BMT) is frequently used to treat patients with metastatic cancer including breast cancer and neuroblastoma. However, the bone marrow of such patients is often contaminated with tumor cells. Recently, we have found that a recombinant adenovirus vector that contains a bcl-x, minigene (a dominant negative inhibitor of the bcl-2 family), called the bcl-x(s) adenovirus, is lethal to cancer cells derived from epithelial tissues, but not to normal human hematopoietic cells. To determine the mechanism, by which this virus spares normal hematopoietic cells, we isolated normal mouse hematopoietic stem cells and infected them with an adenovirus that contains a beta-galactosidase minigene. Such cells do not express beta-galactosidase, indicating that hematopoietic stem cells do not express transgene encoded by adenovirus vectors based upon the RSV-AD5 vector system. When breast cancer cells mixed with hematopoietic cells were infected with the bcl-x(s) adenovirus, cancer cells were selectively killed by the suicide adenoviruses. Hematopoietic cells exposed to the suicide vectors were able to reconstitute the bone marrow of mice exposed to lethal doses of y-irradiation. These studies suggest that adenovirus suicide vectors may provide a simple and effective method to selectively eliminate cancer cells derived from epithelial tissue that contaminate bone marrow to be used for autologous BMT. We therefore propose to initiate a phase I clinical trial to test the safety of this virus in women with breast cancer undergoing high does chemotherapy and autologous BMT.

Adenoviridae↗
PubMed2001

The meroperon of a mercury-resistant Pseudoalteromonas haloplanktis strain isolated from Minamata Bay, Japan.

A mer operon of mercury-resistant Pseudoalteromonas haloplanktis strain M1, isolated from sea water of Minamata Bay, was cloned and analyzed. The mer genes were located in the chromosome and organized as merR-merT-merP-merC-merA-merD, the same order as that in Tn21. However, the orientation of the merR gene is the same as that of other mer genes (opposite direction to Tn21), and merR was cotranscribed with other mer genes, a pattern that has not been previously seen with mer determinants from other Gram-negative bacteria. Furthermore, the amino acid similarities of the corresponding mer gene products between those from strain M1 and Tn21 were unusually low.

Amino Acid Sequence↗
PubMed2001

Allogeneic stem cell transplantation reduces disease progression compared to autologous transplantation in patients with multiple myeloma.

This study compares the probability of disease progression, progression-free survival, and overall survival between patients undergoing an allogeneic or autologous transplant for multiple myeloma using an identical preparative regimen. Patients received a preparative regimen of TBI, busulfan, and cyclophosphamide followed by an allogeneic or autologous transplant. In the allogeneic group (n = 21), six patients received bone marrow and 15 received G-CSF mobilized PBSC; all autologous patients (n = 35) received PBSC mobilized with cyclophosphamide and G-CSF. Allogeneic donors were HLA-identical (n = 20) or one-antigen mismatched (n = 1) siblings. Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus (n = 10), tacrolimus/methotrexate (n = 6), cyclosporine/methotrexate (n = 4), or cyclosporine (n = 1). The groups were evenly matched for gender, pretransplant therapy, disease status at time of transplant, myeloma subtype, and time from diagnosis to transplant. The median age was significantly lower in the allogeneic group (48 vs 55 years, P < 0.01). In the allogeneic group the probabilities of developing acute GVHD grade II-IV and chronic GVHD were 55% and 82%, respectively. The Kaplan-Meier probability of disease progression was significantly lower in the allogeneic group (11% vs 64%, P < 0.001) compared to the autologous group. Although progression-free (60% vs 30%, P = 0.19) and overall survival at 2 years (60% vs 42%, P = 0.39) favored the allogeneic group, this did not reach statistical significance. Within the allogeneic transplant group, patients age 50 years or under had a 3-year overall survival significantly higher when compared to older patients (79% vs 29%, P = 0.03). Using identical preparative regimens, allogeneic transplantation reduced disease progression compared to autologous transplantation for myeloma. This suggests that allogeneic transplantation induces a graft-versus-myeloma (GVM) effect.

Actuarial Analysis↗
PubMed2001

Diversity of silver resistance genes in IncH incompatibility group plasmids.

Silver compounds are used as antimicrobial agents in medicine and bacteria that develop resistance to silver cations (Ag(+)) pose problems similar to those of antibiotic-resistant bacteria. The first set of Ag(+) resistance genes (sil) was from plasmid pMG101, now assigned to the IncHI incompatibility group. Questions of whether sil genes are unique to pMG101 or are more widely found, and whether they are associated with a specific incompatibility group or occur in many plasmid groups and on bacterial chromosomes were addressed. sil genes were identified in five IncH plasmids, but not in plasmids of the IncP incompatibility group. Three sil genes (silP, silR and silE) from these plasmids were PCR-amplified, cloned, sequenced and compared to those of pMG101. Differences of 0-50 nt per kb of sequence were found. Predicted gene products were 0-6% different in amino acid sequence, but the differences did not alter residues thought to be involved in protein function (see supplementary data at http://mic.sgmjournals.org or http://www.uic.edu/depts/mcmi/individual/gupta/index.htm). For representative IncH plasmid R476b and pMG101 the effects of Ag(+) exposure on resistance levels were measured by growth. The inducibility of silC, silR and silE gene expression after Ag(+) exposure was studied by reverse transcriptase (RT)-PCR. Silver resistance increased after Ag(+) exposure for strains carrying plasmid R476b. silC and silE expression from R476b was inducible after Ag(+) exposure and was constitutive and high from pMG101. The mRNA levels for the regulatory gene silR was constitutive for both pMG101 and R476b. Close homologues for silABC(ORF96)RS from pMG101 are clustered on the chromosomes of Escherichia coli strains K-12 and O157:H7, without contiguous silP and silE homologues. Insertion deletions of the E. coli K-12 chromosomal homologues for silA and silP gave Ag(+) hypersensitivity for growth. The silA homologue knockout was complemented back to wild-type resistance by the same gene cloned on a plasmid. Homologues of sil genes have also been identified on other enterobacterial genomes.

Anti-Bacterial Agents↗
PubMed2001

Longitudinal variability of human immunodeficiency virus type 1 RNA viral load measurements by nucleic acid sequence-based amplification and NucliSens assays in a large multicenter study.

Human immunodeficiency virus type 1 (HIV-1) RNA measurements were evaluated within an externally controlled multilaboratory program. Three external standards (1.5 x 10(3) to 1.5 x 10(6) copies/ml) were included in 814 assay runs by four laboratories. Results indicate that HIV-1 RNA levels can be measured with a precision equal to that of the pre-highly active antiretroviral therapy era (standard deviations, +/-0.16 to 0.25 log10 units).

HIV Infections↗
PubMed2000

Functional analysis of gapped microbial genomes: amino acid metabolism of Thiobacillus ferrooxidans.

A gapped genome sequence of the biomining bacterium Thiobacillus ferrooxidans strain ATCC23270 was assembled from sheared DNA fragments (3.2-times coverage) into 1,912 contigs. A total of 2,712 potential genes (ORFs) were identified in 2.6 Mbp (megabase pairs) of Thiobacillus genomic sequence. Of these genes, 2,159 could be assigned functions by using the WIT-Pro/EMP genome analysis system, most with a high degree of certainty. Nine hundred of the genes have been assigned roles in metabolic pathways, producing an overview of cellular biosynthesis, bioenergetics, and catabolism. Sequence similarities, relative gene positions on the chromosome, and metabolic reconstruction (placement of gene products in metabolic pathways) were all used to aid gene assignments and for development of a functional overview. Amino acid biosynthesis was chosen to demonstrate the analytical capabilities of this approach. Only 10 expected enzymatic activities, of the nearly 150 involved in the biosynthesis of all 20 amino acids, are currently unassigned in the Thiobacillus genome. This result compares favorably with 10 missing genes for amino acid biosynthesis in the complete Escherichia coli genome. Gapped genome analysis can therefore give a decent picture of the central metabolism of a microorganism, equivalent to that of a complete sequence, at significantly lower cost.

Amino Acids↗
PubMed2000

Magnetic resonance imaging of ultrasound fields: gradient characteristics.

Phase-contrast magnetic resonance imaging (MRI) is used to image particle displacements arising from a 0.515-MHZ focused ultrasound (US) field. The technique used a phase-locked, self-resonant gradient matched to the US frequency in conjunction with a spin-echo sequence to generate phase images of US-induced displacement parallel to the US propagation direction. The gradient design was numerically optimized to provide maximum linearity and magnitude while minimizing gradient inductance. The windings were fabricated of Litz wire to minimize resistive losses and mounted in an oil-cooled imaging chamber. When driven by a resonance power supply, a peak magnetic field gradient of 0.40 T/m was attained with a peak current of 20 amp in a volume of 53 cm(3), achieving stable oscillation at the required US frequency. Clear detection of the nanometer scale particle motions of the US field was achieved and allowed quantitative, noninvasive visualization of the entire US field. While the required gradient slew rate for US detection is beyond that recommended for in vivo application, this imaging method opens new possibilities for in vitro or ex vivo research in the study of the interaction of US with tissue.

Echo-Planar Imaging↗
PubMed2000

The effect of continuous low dose creatine supplementation on force, power, and total work.

Dietary supplementation (SUP) has become a significant part of athletic training. Studies indicate that creatine (Cr) can enhance short-duration, high-intensity activities. This study examined the effect of 21 days of low dose Cr SUP ( approximately 7.7 g/day) and resistance training on force output, power output, duration of mean peak power output, and total work performed until fatigue. A double-blind protocol was used, where an individual, who was not part of any other aspect of the study, randomly assigned subjects to creatine and placebo groups. Forty-one male university athletes were randomly assigned to either Cr (n = 20) or placebo (n = 21) SUP. On the first and last day of the study, subjects were required to perform concentric bench press movements until exhaustion on an isokinetic dynamometer. The dynamometer was hard-wired to a personal computer, which provided force, velocity, and duration measures. Force and power output until fatigue, were used to determine total work, force-time, and power-time relationships. ANOVA results revealed that the Cr subjects performed more total work until fatigue, experienced significantly greater improvements in peak force and peak power, and maintained elevated mean peak power for a longer period of time. These results indicate that Cr SUP can significantly improve factors associated with short-duration, high-intensity activity.

Adult↗
PubMed1999

Molecular basis for resistance to silver cations in Salmonella.

Here we report the genetic and proposed molecular basis for silver resistance in pathogenic microorganisms. The silver resistance determinant from a hospital burn ward Salmonella plasmid contains nine open reading frames, arranged in three measured and divergently transcribed RNAs. The resistance determinant encodes a periplasmic silver-specific binding protein (SilE) plus apparently two parallel efflux pumps: one, a P-type ATPase (SilP); the other, a membrane potential-dependent three-polypeptide cation/proton antiporter (SilCBA). The sil determinant is governed by a two-component membrane sensor and transcriptional responder comprising silS and silR, which are co-transcribed. The availability of the sil silver-resistance determinant will be the basis for mechanistic molecular and biochemical studies as well as molecular epidemiology of silver resistance in clinical settings in which silver is used as a biocide.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1999

Lower genital tract infections among HIV-infected and high-risk uninfected women: findings of the Women's Interagency HIV Study (WIHS).

BACKGROUND AND OBJECTIVES: Few comparisons of factors associated with sexually transmitted diseases (STDs) and HIV are available for representative samples of American women. GOAL OF THE STUDY: To compare factors associated with STDs in a large sample of women infected with HIV and women not infected with HIV. STUDY DESIGN: A cross-sectional analysis of STDs in 2,058 women seropositive (HIV+) for HIV and 567 women seronegative (HIV-) for HIV. RESULTS: HIV + women were more likely than HIV- women to report previous STDs, with the exceptions of chlamydia and bacterial vaginosis. Both HIV status and CD4 lymphocyte count were associated with evidence of genital ulcerations, warts, and vaginal candidiasis (p <0.001 for all). HIV- women were more apt to report recent vaginal intercourse (p <0.001), a factor that was independently associated with the occurrence of bacterial and protozoan infections. CD4 lymphocyte depletion was the factor most closely associated with the expression of chronic viral infections. CONCLUSIONS: In this North American cohort, HIV+ women were more likely than HIV- women to report previous genital tract infections and symptoms. However, the HIV+ women reported less recent sexual activity and few gonococcal or chlamydial infections.

Adolescent↗
PubMed1999

Mercury resistance in Bacillus cereus RC607: transcriptional organization and two new open reading frames.

The chromosomal mercury resistance determinant of Bacillus cereus RC607 confers resistance to inorganic mercury and to organomercurials. The order of genes in the completed mercury resistance determinant is operator-promoter 1 (O/P1) merR1 merT open reading frame 3 (ORF3) ORF4 merA O/P2 merR2 merB2 merB1. The previously undetermined 1-kb DNA sequence between the merA and merB1 genes includes two significant ORFs, whose predicted protein products are homologous with MerR (the transcriptional regulator) and MerB (the organomercurial lyase enzyme). Two transcriptional start sites (promoters), O/P1 at the beginning of the determinant and O/P2 immediately upstream of the sixth ORF, the newly identified merR2, were mapped by reverse transcriptase (RT) primer extension. A long 6.3-kb mRNA traversing all eight ORFs was shown by RT-PCR. Growth sensitivity measurements in liquid media and cellular mercury volatization assays characterized inducibility and differences in functional activity in B. cereus RC607 and after cloning of the mer determinant into plasmids in Escherichia coli.

Amino Acid Sequence↗
PubMed1999

Multidisciplinary team dynamics in the production of problem-based-learning cases in issues related to older adults.

Two important goals in allied health education are to prepare future allied health professionals to function as members of interdisciplinary teams and to increase their awareness of issues related to the growing older adult population. The responsibility for achieving these goals rests on the faculty and administrators of allied health education programs, who may not themselves be proficient in either of these domains. A multidisciplinary team of health educators and administrators was brought together to produce six problem-based learning (PBL) cases related to older adults. Members of the team represented a variety of disciplines in health care, diverse philosophies of educational development, a variety of roles in allied health education, and differing levels of knowledge of issues related to older adults--parameters similar to those found in the members of an interdisciplinary healthcare team. The methods by which this multidisciplinary group functioned and the dynamics in attaining the goals of the project are presented.

Aged↗
PubMed1998

Effects of intracellular glutathione on sensitivity of Escherichia coli to mercury and arsenite.

The effect of intracellular glutathione on sensitivity to mercuric cations and arsenite anions was studied in Escherichia coli mutants that lack glutathione (gshA) with or without an additional mutation affecting the osmotregulant trehalose. The absence of glutathione increased cellular sensitivity to both Hg2+ and AsO2-. The double mutant was more sensitive to Hg2+ than the single mutant strain. The addition of plasmid resistance determinants of Hg2+ and AsO2- showed additivity between chromosomal genes and plasmid genes. Mercury resistance was increased in the plasmid-containing cells but not up to the level of wild-type cells. Plasmid arsenite resistance was not expressed in the gshA mutant of E. coli.

Arsenites↗