利用放射性核素示踪技术对镉及铬与毛发结合机制的研究

目的 利用放射性核素示踪方法研究内外源性镉、铬与毛发结合的机制，从分子水平探讨目前常用的头发预处理方法能否有选择地清除外源性而保留毛发中内源性镉、铬的含量。方法 提取含有内源性的放射性核素镉、铬的大白鼠鼠毛及外源性放射性核素镉、铬的人发蛋白质，利用柱层析将毛发蛋白质分组，分别测定不同蛋白组分中的放射性镉、铬的活度来确定与镉、铬相互结合的毛发蛋白组分。比较与内外源性镉、铬相结合的蛋白组分来分析核素与毛发结合机制。结果 内外源性镉、铬核素均以与毛发蛋白质相互结合的方式存在于毛发中，而且所结合的蛋白质组分的相对分子量相同。lAEA法和海鸥洗涤剂对内外源性的镉、铬有轻度地洗脱，但Ⅱ玎AN啦和稀硝酸溶液对两种核素有强力的清除效力。结论 由于内外源性镉、铬核素与毛发蛋白质结合的相似性，实验中头发样品的预处理方法在清除外源性核素的同时，在一定程度上也影响头发内源性的核素的含量。     

Association of virus load,CD4 cell count,and treatment with clinical progression in human immunodeficiency virus-infected patients with very low CD4 cell counts

This study prospectively assessed the impact of treatment modality, virus load, and CD4 cell count of <50 cells/mm(3) on human immunodeficiency virus disease progression. The incidence rate of new AIDS disease or death was 54.8 (95% confidence interval, 48.7-59.9) per 100 person-years of follow-up. Independent predictors related to progression were latest CD4 cell count (relative risk [RR], 0.84/10 mm(3) higher; P<.0001), latest hemoglobin level (RR, 0.79/g/L higher; P<.0001), Pneumocystis carinii pneumonia prophylaxis (RR, 0.49; P<.0001), latest body mass index (RR, 0.93/kg/m(2) higher; P=.002), latest virus load (RR, 1.11/log(10) higher; P=.03), and intensity of treatment (RR, 1.82, P=.004; RR 2.27, P<.0001; RR 2.46, P=.0001; RR 2.33 P<.0006; 5.10, P<.0001, respectively, for 4, 3, 2, 1, or no drugs vs. >or=5 drugs). Although reverse causality cannot be excluded, more intense antiviral treatment appears to decrease the risk of progression in immunocompromised patients.     

Intravenous foscarnet for the treatment of severe cytomegalovirus infection in allograft recipients

Foscarnet, trisodium phosphonoformate, was administered intravenously to 6 immunosuppressed patients with life-threatening cytomegalovirus infection. Three of the patients were recipients of a kidney and 3 of a bone-marrow transplant. Favourable clinical responses were seen in 5 of the patients, 2 of whom were still in good health 5 and 8 months after the infection had cleared up. No toxic effect of the drug was detected. The results seem to justify further trials, in which foscarnet should be introduced at an earlier stage of the disease.     

Dependence of human vascular cell surface proteolysis on expression of the urokinase receptor

To delineate the role of binding of urokinase type plasminogen activator (uPA) to its receptor (uPAR) in the local generation of plasmin by endothelium, we transfected spontaneously transformed immortalized human vascular endothelial cells that express high levels of uPA but low levels of uPAR with human uPAR complementary DNA. Compared with nontransfected cell, the stably transformed clonal cell line exhibited (a) a > 10-fold increase in steady-state uPAR mRNA levels documented with Northern blot analysis (n = 3), (b) a 2.8-fold increase in cell surface expression of uPAR protein quantified by enzyme linked immunosorbent assay (n = 3), (c) a 2.9-fold increase in specific binding of radiolabeled single chain uPA (n = 4), and (d) markedly increased matrix adhesion. The participation of uPAR in cell surface proteolysis was apparent based on a 3.0-fold increase in cell associated plasmin activity (n = 3) and a 2.3-fold increase in lysis of noncrosslinked fibrin clots (n = 5). Thus, local generation of plasmin and consequent degradation of fibrin are likely to be promoted by cell surface localization of uPA by uPAR in cellular constituents of the vessel wall. Furthermore, genetic engineering of endothelium to enhance expression of uPAR may confer resistance to thrombosis or restenosis associated with endovascular stents.     

Distribution and Properties of Neutral Ceramidase Activity in Rat Intestinal Tract

Ceramide plays an important role in regulating cell proliferation and apoptosis. Recent studies indicate that generation of ceramide in the intestine from sphingomyelin hydrolysis may be implicated in colon cancer development. The enzymes that catalyze the further hydrolysis of ceramide in the intestine have, however, not been well investigated. Our data reveal the existence of a ceramidase (EC 3.5.1.23) in rat intestinal mucosa with an optimal pH of 7.0. One milligram of mucosal protein is able to hydrolyze 44.0 ± 9.6 nmol of ceramide in 1 hr. The activity is low in the proximal duodenum and increases to a plateau in the proximal jejunum. The activity is then similar throughout the small intestine, until it declines in the distal part of ileum. Some activity is also detectable in the colon. The activity increases slightly in the presence of monomeric bile salt concentrations and sharply at the critical micellar concentration. Similar patterns were observed for both primary (taurocholate) and secondary (taurodeoxycholate) bile salts. The addition of Triton X-100 enhances the ceramidase activity at optimal bile salt concentration. The reaction is linear with time for the first 20 min and the hydrolytic rate declines slowly thereafter. Finally, the activity shows a considerable resistance against tryptic degradation, as 71% of the ceramidase activity remained when the homogenates were preincubated with high concentrations of trypsin. Intestinal mucosa also has a ceramide synthesis activity, with a distribution pattern generally paralleling ceramide hydrolysis activity. In conclusion, intestinal neutral ceramidase has a distinct distribution pattern and bile salt dependence, which enables it to collaborate with intestinal sphingomyelinase in hydrolysis of sphingomyelin.     

Concomitant inactivation of the p53‐ and pRB‐ functional pathways predicts resistance to DNA damaging drugs in breast cancer in?vivo

Chemoresistance is the main obstacle to cancer cure. Contrasting studies focusing on single gene mutations, we hypothesize chemoresistance to be due to inactivation of key pathways affecting cellular mechanisms such as apoptosis, senescence, or DNA repair. In support of this hypothesis, we have previously shown inactivation of either TP53 or its key activators CHK2 and ATM to predict resistance to DNA damaging drugs in breast cancer better than TP53 mutations alone. Further, we hypothesized that redundant pathway(s) may compensate for loss of p53‐pathway signaling and that these are inactivated as well in resistant tumour cells. Here, we assessed genetic alterations of the retinoblastoma gene (RB1) and its key regulators: Cyclin D and E as well as their inhibitors p16 and p27. In an exploratory cohort of 69 patients selected from two prospective studies treated with either doxorubicin monotherapy or 5‐FU and mitomycin for locally advanced breast cancers, we found defects in the pRB‐pathway to be associated with therapy resistance (p‐values ranging from 0.001 to 0.094, depending on the cut‐off value applied to p27 expression levels). Although statistically weaker, we observed confirmatory associations in a validation cohort from another prospective study (n = 107 patients treated with neoadjuvant epirubicin monotherapy; p‐values ranging from 7.0 × 10−4 to 0.001 in the combined data sets). Importantly, inactivation of the p53‐and the pRB‐pathways in concert predicted resistance to therapy more strongly than each of the two pathways assessed individually (exploratory cohort: p‐values ranging from 3.9 × 10−6 to 7.5 × 10−3 depending on cut‐off values applied to ATM and p27 mRNA expression levels). Again, similar findings were confirmed in the validation cohort, with p‐values ranging from 6.0 × 10−7 to 6.5 × 10−5 in the combined data sets. Our findings strongly indicate that concomitant inactivation of the p53‐ and pRB‐ pathways predict resistance towards anthracyclines and mitomycin in breast cancer in vivo.     

Decline in esophageal candidiasis and use of antimycotics in European patients with HIV

BACKGROUND: Esophageal candidiasis (EC) remains one of the most common AIDS defining illnesses in patients with human immunodeficiency virus (HIV) in the era of highly active antiretroviral therapy (HAART), but little is known about factors associated with EC after starting HAART. OBJECTIVES: To describe changes in the use of antimycotic medication, the incidence of EC and factors associated with EC before and after starting HAART. METHODS: Patients from EuroSIDA, a pan-European longitudinal, prospective observational study. Generalized linear models and poisson regression models were used to investigate the relationships. RESULTS: A total of 9,873 patients did not have EC at recruitment, subsequently 537 (15.8%) developed EC. The proportion of patients taking any antimycotic dropped from 18% at January 1995 to 2% at January 2004 (p < 0.0001); the duration of treatment declined from 10 to 3 months over the same period (p < 0.0001). There was a 32% annual decline in the incidence of EC (95% CI 30-35%, p < 0.0001). There was a significant annual decline in the incidence of EC pre-HAART in time-updated, adjusted models, (incidence rate ratio (IRR) 0.80, 95% CI 0.76-0.85, p < 0.0001) but not post-HAART (IRR 0.97; 95% CI 0.90-1.06, p= 0.54). Older patients and those with low CD4 counts had the greatest incidence of EC in the post-HAART era. CONCLUSIONS: There has been a marked decline in the incidence of EC between 1994 and 2004. This was accompanied by a decline in markers associated with fungal disease, including use of antimycotics and a decline in duration of treatment.     

Predictors of immunological failure after initial response to highly active antiretroviral therapy in HIV-1-infected adults: a EuroSIDA study

BACKGROUND: Factors that determine the immunological response to highly active antiretroviral therapy (HAART) are poorly defined. OBJECTIVE: Our aim was to investigate predictors of immunological failure after initial CD4(+) response. METHODS: Data were from EuroSIDA, a prospective, international, observational human immunodeficiency virus (HIV) type 1 cohort. RESULTS: Of 2347 patients with an increase in CD4(+) cell count >or=100 cells/microL within 6-12 months of the initiation of HAART, 550 (23%) subsequently experienced immunological failure (CD4(+) count less than or equal to the pre-HAART value). The incidence of failure was 11.6 incidences/100 person-years of follow-up (95% confidence interval [CI], 10.2-13.4) during the first 12 months and decreased significantly over time (P<.0001). Independent predictors of immunological failure were pre-HAART CD4(+) cell count (per 50% higher; relative hazard [RH], 2.05; 95% CI, 1.83-2.31; P<.0001), time-updated virus load (per 1 log(10) higher; RH, 1.77; 95% CI, 1.64-1.92; P<.0001), and HIV-1 risk behavior (P=.047 for a global comparison of risk groups). CONCLUSION: The risk of immunological failure in patients with an immunological response to HAART diminishes with a longer time receiving treatment and is associated with pretreatment CD4(+) cell count, ongoing viral replication, and intravenous drug use.     

Rapid loss of specific antibodies after pneumococcal vaccination in patients with human immunodeficiency virus-1 infection

Pneumococcal infections are frequently observed in patients with human immunodeficiency virus (HIV) infection and active immunization has been recommended as prophylaxis in this patient group. We studied 103 out-patients with asymptomatic or mildly symptomatic HIV infection with respect to specific IgG and IgG2 pneumococcal antibodies before and after vaccination with a 23-valent pneumococcal polysaccharide vaccine. A significant increase ( > 2-fold) in IgG and IgG2 antibody levels was observed after 1 month in 69/103 patients (67%) with no correlation with the CD4 cell count at the time of vaccination. The response rate was not influenced by concurrent treatment with anti-retroviral monotherapy, or by age or gender. After immunization a strong correlation between IgG and IgG2 anti-pneumococcal antibodies was demonstrated. Nevertheless, 12 months after vaccination the specific antibody titres were not significantly different from pre-vaccination values. In conclusion, antibodies induced by pneumococcal vaccination in patients with HIV infection have a short duration. This raises the question as to whether vaccination will have any impact on clinical end-point in this group of patients.