Cadmium induces apoptosis and genotoxicity in rainbow trout hepatocytes through generation of reactive oxygene species

Cadmium poses a serious environmental threat in aquatic ecosystems but the mechanisms of its toxicity remain unclear. The purpose of this work was first to determine whether cadmium induced apoptosis in trout hepatocytes, second to determine whether or not reactive oxygen species (ROS) were involved in cadmium-induced apoptosis and genotoxicity. Hepatocytes exposed to increasing cadmium concentrations (in the range of 1-10 microM) showed a molecular hallmark of apoptosis which is the fragmentation of the nuclear DNA into oligonucleosomal-length fragments, resulting from an activation of endogenous endonucleases and recognized as a 'DNA ladder' on conventional agarose gel electrophoresis. Exposure of hepatocytes to cadmium led clearly to the DEVD-dependent protease activation, acting upstream from the endonucleases and considered as central mediators of apoptosis. DNA strand breaks in cadmium-treated trout hepatocytes was assessed using the comet assay, a rapid and sensitive single-cell gel electrophoresis technique used to detect DNA primary damage in individual cells. Simultaneous treatment of trout hepatocytes with cadmium and the nitroxide radical TEMPO used as a ROS scavenger, reduced significantly DNA fragmentation, DEVD-related protease activity and DNA strand breaks formation. These results lead to a working hypothesis that cadmium-induced apoptosis and DNA strand breaks in trout hepatocytes are partially triggered by the generation of ROS. Additional studies are required for proposing a mechanistic model of cadmium-induced apoptosis and genotoxicity in trout liver cells, in underlying the balance between DNA damage and cellular defence systems in fish.     

Dietary factors and body mass index in a group of Iranian adolescents: Tehran lipid and glucose study--2

OBJECTIVE: To study the prevalence of overweight and obesity in an adolescent population in Tehran and to determine possible association with energy and nutrient intake and distribution of energy over the day. METHOD: A cross-sectional study on 177 boys and 244 girls between 10-19 years old was performed. Overweight and obesity were defined by using recommended body mass index (BMI) cut-off values for adolescents. Total energy intake, percent of energy derived from protein, carbohydrate and fat and percent of energy supplied by each meal and snack were assessed by means of two 24-hour dietary recalls. RESULTS: Prevalence of overweight and obesity was 10.7 and 5.1 in boys and 18.4 and 2.8 in girls, respectively. The composition of diet was not different between overweight/obese and normal weight subjects. BMI was related with breakfast energy percentage in girls (r = -0.18, p < 0.01), with total energy intake in boys (r = 0.23, p < 0.01), and with lunch energy percentage in both sexes. In boys (r = 0.16, p < 0.05) and in girls (r = 0.22, p < 0.01). CONCLUSION: High prevalence of overweight and obesity among adolescents was seen. In boys some relationship between total energy intake, distribution of energy over the day and BMI was seen. In girls BMI was only related with distribution of energy over the day.     

Estimation of HIV Prevalence,Risk Factors,and Testing Frequency among Sexually Active Men Who Have Sex with Men,Aged 18–64 Years—New York City, 2002

Population-based estimates of human immunodeficiency virus (HIV) prevalence and risk behaviors among men who have sex with men (MSM) are valuable for HIV prevention planning but not widely available, especially at the local level. We combined two population-based data sources to estimate prevalence of diagnosed HIV infection, HIV-associated risk-behaviors, and HIV testing patterns among sexually active MSM in New York City (NYC). HIV/AIDS surveillance data were used to determine the number of living males reporting a history of sex with men who had been diagnosed in NYC with HIV infection through 2002 (23% of HIV-infected males did not have HIV transmission risk information available). Sexual behavior data from a cross-sectional telephone survey were used to estimate the number of sexually active MSM in NYC in 2002. Prevalence of diagnosed HIV infection was estimated using the ratio of HIV-infected MSM to sexually active MSM. The estimated base prevalence of diagnosed HIV infection was 8.4% overall (95% confidence interval [CI] = 7.5–9.6). Diagnosed HIV prevalence was highest among MSM who were non-Hispanic black (12.6%, 95% CI = 9.8–17.6), aged 35–44 (12.6%, 95% CI = 10.4–15.9), or 45–54 years (13.1%, 95% CI = 10.2–18.3), and residents of Manhattan (17.7%, 95% CI = 14.5–22.8). Overall, 37% (95% CI = 32–43%) of MSM reported using a condom at last sex, and 34% (95% CI = 28–39%) reported being tested for HIV in the past year. Estimates derived through sensitivity analyses (assigning a range of HIV-infected males with no reported risk information as MSM) yielded higher diagnosed HIV prevalence estimates (11.0–13.2%). Accounting for additional undiagnosed HIV-infected MSM yielded even higher prevalence estimates. The high prevalence of diagnosed HIV among sexually active MSM in NYC is likely due to a combination of high incidence over the course of the epidemic and prolonged survival in the era of highly active antiretroviral therapy. Despite high HIV prevalence in this population, condom use and HIV testing are low. Combining complementary population-based data sources can provide critical HIV-related information to guide prevention efforts. Individual counseling and education interventions should focus on increasing condom use and encouraging safer sex practices among all sexually active MSM, particularly those groups with low levels of condom use and multiple sex partners At the time this work was conducted, Manning and Marx were with the Epidemic Intelligence Service, Office of Workforce and Career Development, Centers for Disease Control and Prevention, Atlanta, GA, USA; Thorpe, Ramaswamy, Hajat, Marx, Karpati, Mostashari, and Pfeiffer are with the New York City Department of Health and Mental Hygiene, New York, NY, USA; Nash is with the Department of Epidemiology and International Center for AIDS Care and Treatment Programs, Columbia Mailman School of Public Health, New York, NY, USA; Manning is with the Massachusetts Department of Public Health, Bureau of Family and Community Health, Boston, MA, USA.     

Conceptualizing a Quality Plan for Healthcare

Today, health systems around the world are under pressure to create greater value for patients and society; increasing access, improving client orientation and responsiveness, reducing medical errors and safety, restraining utilization via managed care, and implementing priority allocation of resources for high-burden health problems are examples of strategies towards this end. The quality paradigm by virtue of its strategic consumer focus and its methods for achieving operational excellence has proved an effective approach for creating higher value in many sectors. If applied in a deliberate and holistic manner, the quality paradigm can bring about a more cost-effective organization of the health systems. In this article, we apply quality concepts to healthcare in a conceptual format; we characterize the health system's customers and outputs with their quality dimensions. The product of this effort is a blueprint for a customer-driven health system which identifies six types of customers, nine types of outputs and the associated operations. As a preliminary step, a new analysis and definition of health and disease is provided. Rethinking the structure of health system in this manner and the related conceptual model can guide medical research, health sciences education, and health services policy, and help the practitioner to integrate all modern trends in healthcare delivery.     

Differential effects of two kappa-opiate agonists, U-50,488H and U-69,593, on the binding of 3H-(3-MeHis2) thyrotropin-releasing hormone to rat spinal cord and amygdala membranes.

The effect of delta- and kappa-opiate receptor agonists on the binding of 3H-(3-MeHis2) thyrotropin-releasing hormone (3H-MeTRH) to membranes of the spinal cord and amygdala of male Sprague-Dawley rats was determined in an effort to further understand interactions between opiates and TRH receptors. The agonists used were D-Ala2-MePhe4-Gly-ol5-enkephalin (DAMGO, mu-receptor), cyclic D-penicillamine2-D-penicillamine5-enkephalin (DPDPE, delta-receptor), cyclic D-penicillamine2-L-penicillamine5-enkephalin (DPLPE, delta-receptor), D-Ala2-D-Leu5-enkephalin (delta-receptor), U-50,488H and U-69,593 (kappa-receptor). 3H-MeTRH bound to amygdala and spinal cord membranes at a single site with Bmax values of 35.7 +/- 5.4 and 15.8 +/- 2.6 fmol/mg protein, and Kd values of 6.3 +/- 1.1 and 5.2 +/- 0.7 nmol/l, respectively. The competition experiments were carried out at a concentration of 2 nmol/l 3H-MeTRH. The concentration of opiate ranged from 10(-9) to 10(-4) mol/l. DAMGO, DPDPE and DPLPE had no effect on the binding of 3H-MeTRH to amygdala or spinal cord membranes. The two highly selective kappa-agonists differed in their interaction with TRH receptors. Whereas U-69,593 did not modify the binding of 3H-MeTRH, U-50,488H significantly inhibited the binding of 3H-MeTRH to both spinal cord and amygdala membranes. U-50,488H has been found to be 10 times more potent than U-69,593 at the central kappa-opiate receptors and may explain their differential action at the TRH receptors. It is concluded that mu- and delta-opiate agonists do not interact with brain and spinal cord TRH receptors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical pharmacokinetics of the antitumor drug navelbine (5'-noranhydrovinblastine)

Eleven patients with advanced cancer received navelbine (15 mg/m2) as a single i.v. bolus injection. At least 1 week later, the patients were given a 2-fold increased dose of navelbine (30 mg/m2) and, for seven of them, the 30-mg/m2 dose was repeated after a delay longer than a week. After each administration, plasma and urine were collected for 72 h and monitored for navelbine concentration by radioimmunoassay. The comparison of dose-normalized plasma level profiles showed significant time dependence (P less than 0.05) in four of the seven assessable patients. Some patients also exhibited significant (P less than 0.05) nonlinear (dose dependent) kinetic profiles. Only 3 of the 10 appreciable patients were characterized by both time independent and linear profiles. However, the plasma concentration decay curves presented a triphasic shape similar to that obtained with other antitumor Vinca alkaloids and the data were consistent with a three-compartment pharmacokinetic model. The dose and/or time dependence evidenced for most of the patients did not result in marked changes in pharmacokinetic parameters among courses. The pharmacokinetics of navelbine were characterized by a high plasma clearance (0.27 to 1.49 liter.h-1.kg-1), a large distribution volume (8.2 to 48.2 liter.kg-1), and a long terminal half-life (22.1 to 67.8 h). Urine excretion was low (less than 7.9%). Thus, navelbine pharmacokinetics resembles that of other antitumor Vinca alkaloids.     

In vitro glucuronidation of 3'-azido-3'-deoxythymidine by human liver. Role of UDP-glucuronosyltransferase 2 form.

The glucuronidation of 3'-azido-3'-deoxythymidine (AZT) by human liver microsomes and human hepatocytes in culture has been studied in vitro to determine the UDP-glucuronosyltransferase (UDPGT) form conceivably involved in the AZT biotransformation process. The glucuronide of AZT was preliminarily identified through hydrolysis by beta-D-glucuronidase. Brij 58 was shown to be the best activator of AZT glucuronidation by human liver microsomes, as it increased the rate of glucuronide formation 3-fold. The UDPGT activities toward AZT measured in 29 different microsomal fractions was slightly variable among samples (79 to 268 nmol/hr/mg protein). The apparent KM value for AZT glucuronidation was about 5 mM. We sought to determine if various known UDPGT activities (i.e. p-nitrophenol UDPGT, 4-hydroxybiphenyl UDPGT, and DT1-UDPGT) in 18 microsomal samples were correlated with AZT-UDPGT activity. Experiments revealed that only 4-hydroxybiphenyl UDPGT activity was strongly correlated (r = 0.815, p less than 0.001) with AZT-UDPGT activity, whereas no correlation was found for the other UDPGT activities. To determine the isozyme conceivably involved in AZT glucuronidation, we studied the effect of various compounds on AZT glucuronidation. AZT glucuronidation was inhibited by numerous substrates of the UDPGT2, form: morphine (Ki = 1.8 mM), 4-hydroxybiphenyl (Ki = 0.92 mM), and ketoprofen (Ki = 0.75 mM), but also oxazepam, codeine, and chloramphenicol. p-Nitrophenol appeared to be an inhibitor, whereas acetaminophen had no effect. Bilirubin, aspirin, cimetidine, and acyclovir did not inhibit AZT glucuronidation. Since all the inhibitors tested except p-nitrophenol are known to be glucuronidated by the UDPGT2 form, our results strongly suggest the involvement of this isozyme in AZT glucuronidation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of a human liver microsome bank in drug glucuronidation studies

A bank of readily available, well characterized human hepatic microsomal fractions (29 samples from different livers) has been established. The enzymatic characteristics of each microsome sample were determined using three specific UDP-glucuronosyltransferase (UDPGT) substrates (p-nitrophenol for UDPGT₁, 4-hydroxybiphenyl for UDPGT₂A and monodigitoxoside digitoxigenin (DT₁) for UDPGT₇). After characterization, the bank was used to study the phase II biotransformation processes of two drugs: an antiviral, zidovudine (AZT), and an intermediate metabolite of digoxin, monodigitoxoside digoxigenin (DG₁). Results showed a wide interindividual variability for the glucuronidation rate of 4-hydroxybiphenyl, DT₁, AZT and DG₁. Surprisingly, this variability was lower for p-nitrophenol. No significant correlation was found between the various activities except between DG₁ and DT₁ UDPGT activities and 4-hydroxybiphenyl and AZT UDPGT activities. For AZT, further experiments showed that glucuronidation of this antiviral compound was inhibited by 4-hydroxybiphenyl and chloramphenicol but not by morphine, p-nitrophenol, acetaminophen, or bilirubin. Finally, the results strongly suggest the respective involvement of UDPGT₂A and UDPGT₇ in the glucuronidation of AZT and DG₁.