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Accelerated Progression (accelerated + progression)
Selected AbstractsComparison of the aggregation properties, secondary structure and apoptotic effects of wild-type, Flemish and Dutch N-terminally truncated amyloid , peptidesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2001N. Demeester Abstract The Dutch (E22Q) and Flemish (A21G) mutations in the ,APP region of the amyloid precursor protein (APP) are associated with familial forms of Alzheimer dementia. However, patients with these mutations express substantially different clinical phenotypes. Therefore, secondary structure and cytotoxic effects of the three A,(12,42) variants [wild-type (WT), Dutch and Flemish] were tested. At a concentration of 5 µm the aggregation of these peptides followed the order: A,(1,42) WT > A,(12,42) WT > A,(12,42) Flemish >,A,(12,42) Dutch. The stability of the secondary structure of these peptides upon decreasing the trifluoroethanol (TFE) concentration in the buffer was followed by circular dichroism measurements. WT peptides progressively lost their ,-helical structure; this change occurred faster for both the Flemish and Dutch peptides, and at higher percentages of TFE in the buffer, and was accompanied by an increase in ,-sheet and random coil content. Apoptosis was induced in neuronal cells by the A,(12,42) WT and Flemish peptides at concentrations as low as 1,5 µm, as evidenced by propidium iodide (PI) staining, DNA laddering and caspase-3 activity measurements. Even when longer incubation times and higher peptide concentrations were applied the N-truncated Dutch peptide did not induce apoptosis. Apoptosis induced by the full length A,(1,42) peptide was weaker than that induced by its N-truncated variant. These data suggest that N-truncation enhanced the cytotoxic effects of A, WT and Flemish peptides, which may play a role in the accelerated progression of dementia. [source] Chronic immune stimulation accelerates SIV-induced disease progressionJOURNAL OF MEDICAL PRIMATOLOGY, Issue 5 2001François Villinger The contribution of chronic immune stimulation on the progression of lentivirus-induced disease was evaluated in the SIVmac251 macaque model of AIDS. Following SIV inoculation, seroconversion and control of the acute viral replication phase, repeated immune stimulations with tetanus toxoid (TT), keyhole limpet hemocyanin (KLH) and allogeneic peripheral blood mononuclear cells (PBMC) were initiated in four monkeys. These animals showed a significant shortening of survival when compared with eight non-immune-stimulated control animals inoculated with the same route, dose and stock of SIVmac251 (median survival 9.5 months versus 17 months, P=0.010). In addition, when the comparison was extended to another 22 control animals of different origin but inoculated by the same route with similar doses and stocks of SIVmac251, the difference in survival was still significant (9.5 versus 18 months, P=0.003). This accelerated progression of symptomatic disease was not accompanied with significant increases in plasma viral loads, but suboptimal antibody responses to the immunizing antigens were noted, correlating with the length of survival. These findings may have implications for HIV-infected humans suffering from chronic infectious diseases. [source] Barriers to Treatment of Hepatitis C in HIV/HCV-Coinfected Adults with Alcohol ProblemsALCOHOLISM, Issue 9 2006David Nunes Background: Alcohol use and human immune deficiency virus (HIV) infection are both associated with accelerated progression of hepatitis C virus (HCV) disease and reduced response rates to interferon therapy. In this study, we assessed the prevalence of barriers to interferon treatment in a population of HIV/HCV-coinfected patients with current or past alcohol problems and the extent to which they received treatment to address the barriers. Methods: This is a cross-sectional, descriptive analysis of baseline data from a prospective study assessing the impact of HCV and alcohol use on HIV disease progression. Using consensus guidelines, subjects were categorized as having absolute, relative, or no contraindications to interferon therapy for HCV. Absolute contraindications to treatment included heavy alcohol use, decompensated liver disease, CD4 cell count <100 cells/,L, recent needle sharing, and suicidal ideation. Relative contraindications included moderate alcohol use, recent injection drug use, depressive symptoms, and CD4 cell count from 100 to 199 cells/,L. Results: Of 401 HIV-infected subjects, 200 were HCV RNA-positive. Fifty-three percent had an absolute contraindication to interferon therapy, 35% a relative but no absolute contraindication, and only 12% had no contraindication. Of those with an absolute contraindication, 61% reported heavy drinking and the majority (88%) had multiple contraindications. These contraindications were present despite the fact that over 50% were in receipt of substance abuse and mental health treatment. Conclusions: Continued alcohol and drug use as well as depressive symptoms are the major barriers to interferon therapy in HCV/HIV-coinfected subjects and these barriers persist despite high treatment rates for these problems. Therefore, more intensive treatments of alcohol, drug, and mental health issues are needed to improve HCV treatment eligibility in HCV/HIV-coinfected persons. [source] Unique Susceptibility of the Fetal Thymus to Feline Immunodeficiency Virus Infection: An Animal Model for HIV Infection In Utero1AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 5 2001CALVIN M. JOHNSON PROBLEM: Human infants infected in utero with HIV develop thymus insufficiency and progress to AIDS sooner than infants infected peripartum. However, direct analysis of the thymus is difficult due to limited tissue access and variable timing of vertical transmission. METHOD OF STUDY: Fetal and neonatal cats were inoculated with feline immunodeficiency virus (FIV) at an equivalent infectious dose. The thymus, blood, and lymph nodes were harvested and compared at 23 and 46 days post-inoculation (p.i.) and also compared to sham-inoculated, age-matched controls. Lymphocyte phenotypes were analyzed by flow cytometry and virus burden was quantified in histologic sections and by virus isolation from plasma. RESULTS: Fetal cats inoculated with FIV had acute thymus atrophy at birth, which coincided with peak viremia. At 46 days p.i., thymus size and cell composition rebounded and supported increased productive infection. In contrast, neonatal cats inoculated with FIV developed chronic thymus atrophy and degeneration, which was associated with decreasing productive infection and low-level viremia. CONCLUSIONS: The fetal thymus is uniquely vulnerable to acute, transient depletion and high-level productive infection. The neonatal thymus is less vulnerable to acute changes, and responds through progressive atrophy and declining productive infection. Reduced immune competence, as reflected by the failure to control virus replication, may contribute to the accelerated progression of FIV and HIV infections in utero. [source] Arabidopsis Bax inhibitor-1 functions as an attenuator of biotic and abiotic types of cell deathTHE PLANT JOURNAL, Issue 6 2006Naohide Watanabe Summary Programmed cell death (PCD) is a common process in eukaryotes during development and in response to pathogens and stress signals. Bax inihibitor-1 (BI-1) is proposed to be a cell death suppressor that is conserved in both animals and plants, but the physiological importance of BI-1 and the impact of its loss of function in plants are still unclear. In this study, we identified and characterized two independent Arabidopsis mutants with a T-DNA insertion in the AtBI1 gene. The phenotype of atbi1-1 and atbi1-2, with a C-terminal missense mutation and a gene knockout, respectively, was indistinguishable from wild-type plants under normal growth conditions. However, these two mutants exhibit accelerated progression of cell death upon infiltration of leaf tissues with a PCD-inducing fungal toxin fumonisin B1 (FB1) and increased sensitivity to heat shock-induced cell death. Under these conditions, expression of AtBI1 mRNA was up-regulated in wild-type leaves prior to the activation of cell death, suggesting that increase of AtBI1 expression is important for basal suppression of cell death progression. Over-expression of AtBI1 transgene in the two homozygous mutant backgrounds rescued the accelerated cell death phenotypes. Together, our results provide direct genetic evidence for a role of BI-1 as an attenuator for cell death progression triggered by both biotic and abiotic types of cell death signals in Arabidopsis. [source] | |||||||||||||