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Biomedical subjects

C V Paya

Publications and source records attributed to C V Paya.

At least 19 recordsLinked to original sources
PubMed2002

Prevention of fungal infection in transplantation.

Despite significant advances in the diagnosis, prevention, and treatment of fungal infection in transplant recipients, this infection complication remains a major cause of morbidity and mortality. Our understanding of the pathogenesis of the different fungal microorganisms has enabled us to identify patients at risk for such infections. While Candida infection remains a major complication in patients with intra-abdominal solid organ transplantations in which the bowel is surgically manipulated, Aspergillus infection remains the main fungal complication in lung transplantation recipients. The incidence of all types of fungal infection remains around 5-10%, while mortality following Aspergillus infection remains around 70%. Suppression of Candida growth at the time of surgical manipulation of the bowel should be the mainstay of prevention of this infection in intra-abdominal organ transplantation. Fluconazole is effective and relatively safe at 100-400 mg daily for the first 1-3 months post-liver transplantation. Prevention strategies toward Aspergillus infections remain elusive, but a number of manipulations, such as inhaled liposomal preparations post-organ transplantation or the preemptive use or universal prophylaxis of itraconazole are being validated. The next step is to determine the clinical value of molecular diagnostic techniques for the identification and preemptive therapy of patients at risk for the variety fungal infections.

Amphotericin B↗
PubMed2001

Transcription of the RelB gene is regulated by NF-kappaB.

RelA and RelB are two members of the NF-kappaB family that differ structurally and functionally. While RelA is regulated through its cytosolic localization by inhibitor proteins or IkappaB and not through transcriptional mechanisms, the regulation of RelB is poorly understood. In this study we demonstrate that stimuli (TNF or LPS) lead within minutes to the nuclear translocation of RelA, but require hours to result in the nuclear translocation of RelB. The delayed nuclear translocation of RelB correlates with increases in its protein synthesis which are secondary to increases in RelB gene transcription. RelA is alone sufficient to induce RelB gene transcription and to mediate the stimuli-driven increase in RelB transcription. Cloning and characterization of the RelB 5' untranslated gene region indicates that RelB transcription is dependent on a TATA-less promoter containing two NF-kappaB binding sites. One of the NF-kappaB sites is primarily involved in the binding of p50 while the other one in the binding and transactivation by RelA and also RelB. Lastly, it is observed that p21, a protein involved in cell cycle control and oncogenesis known to be regulated by NF-kappaB, is upregulated at the transcriptional level by RelB. Thus, RelB is regulated at least at the level of transcription in a RelA and RelB dependent manner and may exert an important role in p21 regulation.

5' Untranslated Regions↗
PubMed2001

Allograft rejection predicts the occurrence of late-onset cytomegalovirus (CMV) disease among CMV-mismatched solid organ transplant patients receiving prophylaxis with oral ganciclovir.

The natural history of cytomegalovirus (CMV) disease associated with solid organ transplantation has been modified as a result of the widespread use of antiviral prophylaxis. Anecdotal reports have indicated a reduction of CMV disease at the expense of its later occurrence after completion of ganciclovir prophylaxis. The present study investigated the occurrence of CMV disease and its risk factors among 37 liver and kidney transplant recipients with CMV D+/R- status who received oral ganciclovir during the first 100 days posttransplantation. CMV disease occurred in 9 patients (24.3%) at a median of 144 days posttransplantation (range, 95-190 days). Allograft rejection was found to be strongly associated with the occurrence of late-onset CMV disease (risk ratio, 6.6; 95% confidence interval, 1.4-32.1; P=.02). Thus, CMV D+/R- solid organ transplant recipients receiving 3 months of oral ganciclovir who develop allograft rejection during the period of antiviral prophylaxis may benefit from extended and/or enhanced antiviral prophylaxis to prevent late-onset CMV disease.

Administration, Oral↗
PubMed2001

Prevention of fungal and hepatitis virus infections in liver transplantation.

Invasive fungal infections, especially those caused by Candida albicans, and recurrence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection after transplantation are common complications in orthotopic liver transplant (OLT) recipients. Candida species account for >50% of all invasive fungal infections, which occur in 10%--15% of OLT recipients. The epidemiology and pathogenesis of invasive fungal infections are unique to each type of organism. Fluconazole is effective and safe in the prevention of Candida infection after OLT. Preventive measures against Aspergillus or Cryptococcus remain ill defined. Both HBV and HCV recur almost universally after OLT in infected individuals. The natural course of HBV and HCV, leading to end-stage liver damage, is accelerated. In OLT patients, administration of immunoglobulin with high titers against HBV, alone and/or in combination with lamivudine, immediately after transplantation reduces the recurrence of HBV. The combination of interferon and ribavirin is mildly effective in OLT patients who have evidence of recurrent hepatitis, and additional alternatives are being evaluated.

Antifungal Agents↗
PubMed2001

Fusarium infection after solid-organ transplantation.

We describe a case of soft tissue infection caused by Fusarium species in a heart-liver transplant recipient, and review the cases of fusarial infection reported among solid-organ transplant (SOT) recipients. Unlike fusarial infection in patients with hematologic malignancies or bone marrow transplants, fusarial infection in SOT recipients tends to be localized, occurs later in the posttransplantation period, and has a better outcome. Surgical resection, when possible, and prolonged treatment with amphotericin provide the most effective form of therapy.

Amphotericin B↗
PubMed2001

Clinical evaluation of a new recombinant antigen-based cytomegalovirus immunoglobulin M immunoassay in liver transplant recipients.

BACKGROUND: Human cytomegalovirus (CMV) is a significant cause of morbidity and mortality among transplant recipients. Monitoring transplant recipients by CMV IgM serology has been questioned by several studies due to the reported insensitivity of serologic tests relative to antigen detection methods. METHODS: In this retrospective study, we have evaluated the performance of the new recombinant antigen-based Abbott AxSYM CMV IgM assay and compared it with CMV culture technique in a cohort of 40 liver transplant recipients who did not receive antiviral prophylaxis. RESULTS: The sensitivity, specificity, and positive and negative predictive values for detection of CMV disease by the AxSYM CMV IgM assay were 90.0%, 60.0%, 69.2%, and 85.7%, respectively, and by culture the values were 100%, 55.0%, 69.0%, and 100%, respectively. Detection of CMV IgM occurred before or at the time of CMV disease in only R+ recipients. CONCLUSION: Although this assay is a sensitive test for CMV-specific IgM, detection of CMV IgM preceded detection of virus by culture in patients only when the liver transplant recipient was CMV immune before transplantation (R+).

Antibodies, Viral↗
PubMed2001

Prevention of cytomegalovirus disease in recipients of solid-organ transplants.

The introduction and combination of more-potent immunosuppressive regimens, and the increased transplantation of organs into more severely ill patients, have again placed cytomegalovirus (CMV) disease in the spotlight of posttransplantation complications. Both direct and associated complications related to CMV need to be considered in understanding the pathogenesis of CMV infection after solid-organ transplantation. New diagnostic methods with higher sensitivity for the detection of CMV and the ability to quantify CMV indicate that low levels of CMV replication are present in many patients who don't have clinical symptoms ascribed to CMV infection. How these low levels of CMV replication impact the outcome of the transplanted graft remains unknown. In addition, there needs to be further study regarding whether only patients at high risk for developing CMV disease or, also, those with clinically asymptomatic levels of CMV replication should be the target of effective preventive regimens. This review summarizes our current knowledge of the pathogenesis of CMV infection after solid-organ transplantation, and it outlines different effective preventive regimens and approaches.

Antiviral Agents↗
PubMed2001

Economic impact of cytomegalovirus in solid organ transplantation.

Cytomegalovirus (CMV) infection has a direct effect on morbidity in solid organ transplantation patients, and indirect effects related to the development of opportunistic infections, allograft rejection, and patient mortality. Although intuitively it follows that costs attributable to CMV infections would be increased, direct proof has remained elusive. Accumulating evidence suggests, however, that CMV infection has a significant impact on the costs to transplantation programs, particularly in seronegative recipients of seropositive allografts (D+/R-), and additional costs may be incurred through the effects on CMV potentiating the risks of various opportunistic infections leading to graft rejection.

Antiviral Agents↗
PubMed2001

Heme protein-induced chronic renal inflammation: suppressive effect of induced heme oxygenase-1.

BACKGROUND: Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme; its inducible isozyme, HO-1, protects against acute heme protein-induced nephrotoxicity and other forms of acute tissue injury. This study examines the induction of HO-1 in the kidney chronically inflamed by heme proteins and the functional significance of such an induction of HO-1. METHODS: Studies were undertaken in a patient with chronic tubulointerstitial disease in the setting of paroxysmal nocturnal hemoglobinuria (PNH), in a rat model of chronic tubulointerstitial nephropathy caused by repetitive exposure to heme proteins, and in genetically engineered mice deficient in HO-1 (HO-1 -/-) in which hemoglobin was repetitively administered. RESULTS: The kidney in PNH evinces robust induction of HO-1 in renal tubules in the setting of chronic inflammation. The heme protein-enriched urine from this patient, but not urine from a healthy control subject, induced expression of HO-1 in renal tubular epithelial cells (LLC-PK1 cells). A similar induction of HO-1 and related findings are recapitulated in a rat model of chronic inflammation induced by repetitive exposure to heme proteins. Additionally, in the rat, the administration of heme proteins induces monocyte chemoattractant protein (MCP-1). The functional significance of HO-1 so induced was uncovered in the HO-1 knockout mouse: Repeated administration of hemoglobin to HO-1 +/+ and HO-1 -/- mice led to intense interstitial cellular inflammation in HO-1 -/- mice accompanied by striking up-regulation of MCP-1 and activation of one of its stimulators, nuclear factor-kappaB (NF-kappaB). These findings were not observed in similarly treated HO-1 +/+ mice or in vehicle-treated HO-1 -/- and HO-1 +/+ mice. CONCLUSION: We conclude that up-regulation of HO-1 occurs in the kidney in humans and rats repetitively exposed to heme proteins. Such up-regulation represents an anti-inflammatory response since the genetic deficiency of HO-1 markedly increases activation of NF-kappaB, MCP-1 expression, and tubulointerstitial cellular inflammation.

Adult↗
PubMed2001

Cryptosporidium parvum activates nuclear factor kappaB in biliary epithelia preventing epithelial cell apoptosis.

BACKGROUND & AIMS: Our previous studies have shown that Cryptosporidium parvum induces biliary epithelial cell apoptosis in vivo and causes apoptosis in bystander uninfected biliary epithelia in vitro. We analyzed C. parvum-induced nuclear factor kappa B (NF-kappaB) activation in human biliary epithelial cells and assessed its relevance to epithelial cell apoptosis. METHODS: In vitro models of cryptosporidial infection using a human biliary epithelial cell line were used to assay C. parvum- induced NF-kappaB activation and associated apoptosis. RESULTS: Degradation of I(kappa)B and nuclear translocation of the NF-kappaB family of proteins (p65 and p50) were observed in the biliary epithelial cell cultures directly exposed to the parasite. Activation of NF-kappaB was found only in directly infected cells (but not in bystander uninfected cells). A time-dependent secretion of a known NF-kappaB gene product, interleukin 8, from infected cell cultures was detected. C. parvum-induced biliary epithelial cell apoptosis was limited to bystander uninfected cells. In contrast, inhibition of NF-kappaB activation resulted in apoptosis in directly infected cells and significantly enhanced C. parvum-induced apoptosis in bystander uninfected cells. CONCLUSIONS: These observations support the concept that, while C. parvum triggers host cell apoptosis in bystander uninfected biliary epithelial cells, which may limit spread of the infection, it directly activates the NF-kappaB/I(kappa)B system in infected biliary epithelia thus protecting infected cells from death and facilitating parasite survival and propagation.

Animals↗
PubMed2001

Comparative quantitation of cytomegalovirus (CMV) DNA in solid organ transplant recipients with CMV infection by using two high-throughput automated systems.

Cytomegalovirus (CMV) DNA quantitation in clinical specimens is progressively becoming a cornerstone in the diagnosis and management of CMV infection in the immunocompromised host. We evaluated two automated and reproducible PCR tests, the LightCycler (Roche Molecular Biochemicals, Indianapolis, Ind.) and the COBAS AMPLICOR CMV Monitor (Roche Diagnostics, Pleasanton, Calif.), for the detection of CMV DNA in blood samples from transplant recipients with CMV infection as determined by shell vial culture. Following a log transformation analysis, the mean CMV DNA in plasma (PL), whole blood (WB), peripheral blood leukocytes (PBL), and peripheral blood mononuclear cells (PBMC) using the LightCycler was 6.79 copies per ml, 7.23 copies per ml, 6.38 copies per 2 x 10(6) cells, and 6.27 copies per 2 x 10(6) cells, respectively. This compares to 7.86 copies per ml, 8.37 copies per ml, 7.59 copies per 2 x 10(6) cells, and 7.44 copies per 2 x 10(6) cells, respectively, using COBAS AMPLICOR CMV Monitor. While higher CMV DNA levels were observed for the various blood compartments analyzed using COBAS AMPLICOR CMV Monitor, a high degree of correlation was evident between the two automated systems (jackknife correlation r = PL 0.77 [95% confidence interval (CI); 0.64, 0.90], WB 0.77 [95% CI; 0.62, 0.92], PBL 0.77 [95% CI; 0.67, 0.88], and PBMC 0.81 [95% CI; 0.72, 0.89], all P < 0.001). Therefore, we conclude that either automated diagnostic system is accurate for CMV DNA quantitation.

Adult↗
PubMed2001

NF-kappaB cis-acting motifs of the human immunodeficiency virus (HIV) long terminal repeat regulate HIV transcription in human macrophages.

The role of NF-kappaB in the reactivation of human immunodeficiency virus (HIV) from latency in CD4 T lymphocytes is well documented. However, its role in driving HIV transcription in human macrophages, which contain a constitutive nuclear pool of NF-kappaB, is less well understood. In this study we have investigated the role that the constitutive pool of NF-kappaB and the NF-kappaB cis-acting motifs of the HIV long terminal repeat (LTR) play in regulating HIV transcription in human monocytic cells and primary macrophages. Inhibition of the constitutive nuclear pool of NF-kappaB (RelA and RelB) in the promonocytic U937 cell line using dominant-negative IkappaBalpha significantly decreases HIV replication. Moreover, it is demonstrated that in the differentiated monocytic cell line THP1, which contains a constitutive nuclear pool of NF-kappaB (RelB),an HIV provirus containing mutations of the kappaB cis-acting sites in the LTR is transcriptionally impaired. Reduction of the constitutive pool of NF-kappaB in human macrophages by an adenovirus vector expressing a dominant-negative IkappaBalpha also reduces HIV transcription. Lastly, mutation of the NF-kappaB cis-acting sites in the LTR of an R5 HIV provirus completely abrogates the first cycle of HIV transcription. These studies indicate that the cis-acting NF-kappaB motifs of the HIV LTR are critical in initiating HIV transcription in human macrophages and suggest that the constitutive nuclear pool of NF-kappaB is important in regulating HIV transcription in these cells.

Base Sequence↗
PubMed2001

IkappaB kinase-dependent chronic activation of NF-kappaB is necessary for p21(WAF1/Cip1) inhibition of differentiation-induced apoptosis of monocytes.

The molecular mechanisms regulating monocyte differentiation to macrophages remain unknown. Although the transcription factor NF-kappaB participates in multiple cell functions, its role in cell differentiation is ill defined. Since differentiated macrophages, in contrast to cycling monocytes, contain significant levels of NF-kappaB in the nuclei, we questioned whether this transcription factor is involved in macrophage differentiation. Phorbol 12-myristate 13-acetate (PMA)-induced differentiation of the promonocytic cell line U937 leads to persistent NF-kappaB nuclear translocation. We demonstrate here that an increased and persistent IKK activity correlates with monocyte differentiation leading to persistent NF-kappaB activation secondary to increased IkappaBalpha degradation via the IkappaB signal response domain (SRD). Promonocytic cells stably overexpressing an IkappaBalpha transgene containing SRD mutations fail to activate NF-kappaB and subsequently fail to survive the PMA-induced macrophage differentiation program. The differentiation-induced apoptosis was found to be dependent on tumor necrosis factor alpha. The protective effect of NF-kappaB is mediated through p21(WAF1/Cip1), since this protein was found to be regulated in an NF-kappaB-dependent manner and to confer survival features during macrophage differentiation. Therefore, NF-kappaB plays a key role in cell differentiation by conferring cell survival that in the case of macrophages is mediated through p21(WAF1/Cip1).

Apoptosis↗
PubMed2001

Chemokine-receptor activation by env determines the mechanism of death in HIV-infected and uninfected T lymphocytes.

There is considerable confusion concerning the mechanism of lymphocyte death during HIV infection. During the course of HIV infection, M-tropic viruses (R5) that use CCR5 chemokine coreceptors frequently evolve to T-tropic viruses (X4) that use CXCR4 receptors. In this study we show that activation of the CD4 or CCR5 receptor by R5 HIVenv causes a caspase 8-dependent death of both uninfected and infected CD4 T cells. In contrast, CXCR4 activation by X4 HIVenv induces a caspase-independent death of both uninfected CD4 and CD8 T cells and infected CD4 cells. These results suggest that activation of the chemokine receptor by HIVenv determines the mechanism of death for both infected and uninfected T lymphocytes.

Apoptosis↗
PubMed2001

Cytomegalovirus (CMV) resistance to antivirals.

This article reviews the biology of cytomegalovirus (CMV), the approved antiviral therapies, and mechanisms of resistance to these drugs. The rates of resistance development in clinical trials are presented, as are the assays for testing susceptibility by phenotypic and genotypic methods. Factors that favor the development of clinical and in vitro antiviral resistance are discussed. Finally, approaches to altering antiviral therapy as resistance develops are outlined.

Antiviral Agents↗
PubMed2000

Human beta-herpesvirus interactions in solid organ transplant recipients.

The replication of beta-herpesviruses-cytomegalovirus (CMV), human herpesvirus (HHV)-6, and HHV-7-and their association with CMV disease and response to antiviral therapy were prospectively investigated in 33 liver transplant recipients not given antiviral prophylaxis. CMV, HHV-6, and HHV-7 DNA were detected within 8 weeks after transplantation in 70%, 33%, and 42% of the patients, respectively. The univariate association between CMV disease and the 3 beta-herpesviruses was more significant by virus load quantitation than by qualitative detection of DNA. This association with high levels of CMV, HHV-6, and HHV-7 (P<.001,.022, and.001, respectively) occurred mainly in CMV-seronegative recipients of transplants from CMV-seropositive donors. Antiviral therapy with ganciclovir (Gcv) reduced the load of CMV and HHV-6 and HHV-7. These results suggest that CMV disease in transplant recipients is related to the unique interaction of the 3 beta-herpesviruses and is ultimately reduced after intravenous Gcv treatment.

Antibodies, Viral↗
PubMed2000

The bile acid taurochenodeoxycholate activates a phosphatidylinositol 3-kinase-dependent survival signaling cascade.

Liver injury during cholestasis reflects a balance between the effects of toxic and nontoxic bile acids. However, the critical distinction between a toxic and nontoxic bile acid remains subtle and unclear. For example, the glycine conjugate of chenodeoxycholate (GCDC) induces hepatocyte apoptosis, whereas the taurine conjugate (TCDC) does not. We hypothesized that the dissimilar cellular responses may reflect differential activation of a phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathway. In the bile acid-transporting McNtcp.24 rat hepatoma cell line, TCDC, but not GCDC, stimulated PI3K activity. Consistent with this observation, inhibition of PI3K rendered TCDC cytotoxic, and constitutive activation of PI3K rendered GCDC nontoxic. Both Akt and the atypical protein kinase C isoform zeta (PKCzeta) have been implicated in PI3K-dependent survival signaling. However, TCDC activated PKCzeta, but not Akt. Moreover, inhibition of PKCzeta converted TCDC into a cytotoxic agent, whereas overexpression of wild-type PKCzeta blocked GCDC-induced apoptosis. We also demonstrate that TCDC activated nuclear factor kappaB (NF-kappaB) in a PI3K- and PKCzeta-dependent manner. Moreover, inhibition of NF-kappaB by an IkappaB super-repressor rendered TCDC cytotoxic, suggesting that NF-kappaB is also necessary to prevent the cytotoxic effects of TCDC. Collectively, these data suggest that some hydrophobic bile acids such as TCDC activate PI3K-dependent survival pathways, which prevent their otherwise inherent toxicity.

Adenoviridae↗