Endothelin-induced inositol phosphate formation in rat kidney. Studies on receptor subtypes, G-proteins and regulation during ontogenesis

The aim of this study was to characterize the properties of endothelin (ET)-receptor subtypes mediating inositol phosphate (IP)-formation in rat kidney and their regulation during ontogenesis. In renal cortical slices of adult rats (12–16 weeks old) ET's concentration-dependently increased IP-formation with an order of potency ET -1 ET 3. While the non-selective ET receptor antagonist bosentan (10 M) completely suppressed ET-induced IP-formation, the ETA-receptor antagonist BQ-123 (10 M) inhibited it only by 70%, the ET_B-receptor antagonist IRL 1038 (1 M) by 25%; combined application of BQ-123 + IRL 1038 caused complete inhibition of ET-1-induced IP-formation. Pretreatment of isolated renal cells with pertussis toxin (PTX, 500 ng/ml) overnight did not attenuate but significantly increased ET-1-induced IP-formation. Ontogenetic studies in renal slices from neonatal, 1, 2, 3, 6, 12 and 24 weeks old rats revealed that ET-1-induced IP-formation maturation-dependently declined being highest in neonatal rats (increase: 169% over basal) and lowest in 24 weeks old rats (increase: 47% over basal). This decline in ET-induced IP-formation was accompanied by a decrease in renal ET receptor number and the amount of immunodetectable G_q/11 (assessed by Western-blotting using the QL-antiserum). Moreover, ET receptor subtypes changed during the maturation process: from neonates to 12 weeks old rats number and functional responsiveness of ET_A-receptors declined, while that of ET_B-receptors increased. We conclude that in adult rat renal cortex ET-induced IP-formation is mediated by activation of both ET_A- and ET_B-receptors and does not involve a PTX-sensitive G-protein. ET-induced IP-formation declines during the maturation process; this is associated with a decrease in ET-receptor number and the immunodetectable amount of G_q/11.     

Cytochrome P450 3A4 is the major enzyme responsible for the metabolism of laquinimod, a novel immunomodulator.

In the present study, the involvement of cytochrome P450 enzyme(s) in the primary metabolism of laquinimod, a new orally active immunomodulator, has been investigated in human liver microsomes. Hydroxylated and dealkylated metabolites were formed. The metabolite formation exhibited single enzyme Michaelis-Menten kinetics with apparent KM in the range of 0.09 to 1.9 mM and Vmax from 22 to 120 pmol/mg/min. A strong correlation between the formation rate of metabolites and 6beta-hydroxylation of testosterone was obtained within a panel of liver microsomes from 15 individuals (r2 = 0.6 to 0.94). Moreover, ketoconazole and troleandomycin, specific inhibitors of CYP3A4 metabolism, demonstrated a significant inhibition of laquinimod metabolism. Furthermore, in incubations with recombinant CYP3A4, all the primary metabolites were formed. In vitro interaction studies with CYP3A4 substrates and possible concomitant medication demonstrated that laquinimod inhibits the metabolism of ethinyl estradiol with an IC50 value of about 150 microM, which is high above the plasma level of laquinimod after clinically relevant doses. Ketoconazole, troleandomycin, erythromycin, prednisolone, and ethinyl estradiol inhibited the metabolism of laquinimod, and IC50 values of 0.2, 11, 24, 87, and 235 microM, respectively, were calculated. In conclusion, the present study demonstrates that laquinimod is a low affinity substrate for CYP3A4 in human liver microsomes. The likelihood for in vivo effects of laquinimod on the metabolism of other CYP3A4 substrates is minor. However, inhibitory effects on the metabolism of laquinimod by potent and specific inhibitors of CYP3A4, such as ketoconazole, are anticipated and should be considered in the continued clinical program for laquinimod.     

Comparing Medications in a Therapeutic Area Using an NNT Model

OBJECTIVES: Clinicians are told to use the number needed to treat (NNT) to compare the benefits of therapeutic strategies, and researchers are asked to report results this way, generally without considering differences among the studies from which these were derived. METHODS: The crude NNT currently advocated is compared to the NNT standardized for a common outcome, follow-up time, study population and comparator. An NNT model for cardiovascular disease is described as an example that addresses differences among studies of secondary prevention of cardiovascular disease. Crude NNTs are compared to those obtained from the model. RESULTS: Follow-up in the 18 trials identified varied from 1.0 to 6.2 years; rates of cardiovascular events in the untreated subgroups ranged from 4.8% to 45.9%. The crude NNTs were more variable (9.1-163.7) than those obtained from the model (9.1-75.2). The effect of standardization was substantial in some cases, with proportional changes ranging from a 91% decrease to a 223% increase. CONCLUSION: Using an NNT model to account for differences in study design allows for more meaningful comparisons.     

Phylogenetic reconstruction of Mycobacterium tuberculosis within four settings of the Caribbean region: tree comparative analyse and first appraisal on their phylogeography.

In order to compare phylogenetic methods and to reconstruct the evolutionary history of the tubercle bacilli, a set of macro-array-based genotyping data of Mycobacterium tuberculosis clinical isolates (called spoligotyping for spacer oligonucleotide typing, which assays the variability of the Direct Repeat -DR- locus), was analyzed in four settings of the Caribbean region (Guadeloupe, Martinique, Cuba and Haiti). A set of 47 alleles, split into 26 shared and 21 unique alleles) representative of 321 individual M. tuberculosis clinical isolates from patients residing in the above regions was studied. The following methods (and software in brackets) were investigated: numerical taxonomy distance methods (TAXOTRON), maximum parsimony procedure (PAUP), median-joining networks (NETWORK), and nested clade analysis (GEODIS). Results using these methods were analyzed, compared and discussed. The latter method (GEODIS) was investigated in detail by introducing geographical data together with genetic variability results to detect a link between population structure and population history, and to test the null hypothesis of no association between geography and genotypes. Irrespective of the methods used, our findings demonstrate that a core structure of four families (or clades) of M. tuberculosis strains is highly prevalent within the islands studied, indirectly reflecting passed colonization history of these different settings. Specificity of M. tuberculosis genotypes in each of the islands is discussed in the light of their respective colonial and contemporary histories.     

Retrospective analysis of selective lymphadenectomy in apparent early-stage endometrial cancer.

PURPOSE: Selective lymphadenectomy is widely accepted in the management of endometrial cancer. Purported benefits are individualization of adjuvant therapy based on extent of disease and resection of occult metastases. Our goal was to assess effects of the extent of selective lymphadenectomy on outcomes in women with apparent stage I endometrial cancer at laparotomy. PATIENTS AND METHODS: Patients with endometrial cancer who received primary surgical treatment between 1973 and 2002 were identified through an institutional tumor registry. Inclusion criteria were clinical stage I/IIA disease and procedure including hysterectomy and selective lymphadenectomy (pelvic or pelvic + aortic). Exclusion criteria included presurgical radiation, grossly positive lymph nodes, or extrauterine metastases at laparotomy. Recurrence and survival were analyzed using Kaplan-Meier analysis and Cox proportional hazards model. RESULTS: Among 509 patients, the median number of lymph nodes removed was 15 (median pelvic, 11; median aortic, three). Pelvic and aortic node metastases were found in 24 (5%) of 509 patients and 11 (3%) of 373 patients, respectively. Patients with poorly differentiated cancers having more than 11 pelvic nodes removed had improved overall survival (hazard ratio [HR], 0.25; P < .0001) and progression-free survival (HR, 0.26; P < .0001) compared with patients having poorly differentiated cancers with 11 or fewer nodes removed. Number of nodes removed was not predictive of survival among patients with cancers of grade 1 to 2. Performance of aortic selective lymphadenectomy was not associated with survival. Three (27%) of 11 patients with microscopic aortic nodal metastasis are alive without recurrence. CONCLUSION: These data add to the literature documenting the possible therapeutic benefit of selective lymphadenectomy in management of patients with apparent early-stage endometrial cancer.     

Cytochrome P450 epoxygenases as EDHF synthase(s)

The metabolism of arachidonic acid by cytochrome P450 (CYP) epoxygenases generates epoxyeicosatrienoic acids (EETs) which affect numerous cellular process including Ca(2+) signaling and the activity of Ca(2+)-dependent K(+) channels. The expression of the CYP epoxygenase(s) that generate EETs in endothelial cells is not constitutive but is determined by a number of physical (fluid shear stress and cyclic stretch) and pharmacological stimuli which also affect responses attributed to an endothelium-derived hyperpolarizing factor (EDHF). This review summarizes the role played by EETs, and the enzymes that generate and metabolize them, in EDHF-mediated responses.     

Food effects on tablet disintegration.

The aims of the present study was to investigate if food components, as represented by a multi-component nutritional drink for tube feeding, could affect tablet disintegration of standard tablets in vitro as well as in vivo and propose a mechanism for potential food effects on tablet disintegration. The tablet disintegration was delayed between 5 min and more than 1h in the simulated gastric fed medium compared to a simple buffer. This effect was dependent on the tablet composition. A similar delay in tablet disintegration was also found in vivo after administration of the nutritional drink to three Labradors as observed by removing the tablet from the stomach at different times through a gastric fistula. The delay in tablet disintegration appeared to be caused by precipitation of a film, mainly consisting of protein, on the tablet surface as indicated by disintegration studies with pure nutrients, identification by IR spectroscopy of contents of precipitates obtained in a model study were the nutrients were incubated with different tablet excipients and visual observations of tablets exposed to the simulated fed medium. The drug dissolution of a soluble compound, metoprolol tartrate, from a standard tablet was also strongly delayed in the simulated fed medium. In conclusion, food, could significantly delay tablet disintegration and drug dissolution in the stomach by formation of a film around the tablets. This effect could be monitored by a simple in vitro disintegration test using a test medium based on a nutritional drink. More studies are needed to investigate the significance of the slow tablet disintegrations on bioavailability and for which types of food the present effect occurs.     

A conceptual framework addressing the complex labour market dynamics of the work-to-retirement process

The way in which retirement is conceptualized and measured is likely to influence the research findings. The previous literature has addressed a wide range of elements related to the complex work-to-retirement process, such as early, late and partial retirement, statutory retirement, work disability and unemployment paths to retirement, or different types of bridge employment. However, conceptual clarity in terms of connections between the different elements is called for. We introduce a conceptual framework of the work-to-retirement process to guide its future measurement. Together with information on the statutory retirement age, the main elements of the framework are based on employment and pension receipt, acknowledging that these may overlap. The framework is flexible to the user, providing the possibility to add various specifications—e.g. of types of employment, types of pension receipt, unemployment, and being outside the labour force—depending on the study context and aims. The framework highlights the complexity of the work-to-retirement process, bringing forth its multifaceted, multiphased and multidirectional features. Accounting for such complexity in later-life labour market dynamics helps to elaborate what is actually addressed when investigating “retirement”. Our conceptual framework can be utilized to enhance well-defined, precise and comparable measurement of the work-to-retirement process in studies.     

The differentiated roles of health in the transition from work to retirement – conceptual and methodological challenges and avenues for future research

ObjectivesThe aim of this discussion paper is to (i) identify the differentiated roles of health in the work–retirement transition, and, with respect to these, (ii) highlight topics related to conceptual and methodological problems and challenges in research, and (iii) present avenues for future research.MethodsThis discussion paper summarizes an OMEGA-NET working group discussion ongoing from November 2018 to September 2021 with face-to-face and online meetings as well as a written online discourse.Results‘Health’ and ‘retirement’ are ambiguous concepts. With respect to both, in retirement research, the choice of concept and indicator influences the findings. In addition, the impact of health on retirement is not necessarily a direct one, but can be influenced by further factors such as the ability, motivation and opportunity to work. The strong overall association of poor health with retiring early (path 1) bears the risk of masking distinct and deviating mechanisms in subgroups. In fact, there is evidence that also good health may lead to early retirement (path 2), while both poor health (path 3) and good health (path 4) may also make people retire later.ConclusionsAn increased awareness of the differentiated roles that health may have in the work–retirement transition as outlined in this discussion paper may support research to address questions relevant for policy and practice and increase the impact of research. Recommendations for occupational health and social research are given.     

Evaluation of a Supervised Adapted Physical Activity Program Associated or Not with Oral Supplementation with Arginine and Leucine in Subjects with Obesity and Metabolic Syndrome: A Randomized Controlled Trial

Background: In patients with obesity and metabolic syndrome (MetS), lifestyle interventions combining diet, in particular, and physical exercise are recommended as the first line treatment. Previous studies have suggested that leucine or arginine supplementation may have beneficial effects on the body composition or insulin sensitivity and endothelial function, respectively. We thus conducted a randomized controlled study to evaluate the effects of a supervised adapted physical activity program associated or not with oral supplementation with leucine and arginine in MetS-complicated patients with obesity. Methods: Seventy-nine patients with obesity and MetS were randomized in four groups: patients receiving arginine and leucine supplementation (ALs group, n = 20), patients on a supervised adapted physical activity program (APA group, n = 20), patients combining ALs and APA (ALs+APA group, n = 20), and a control group (n = 19). After the baseline evaluation (m0), patients received ALs and/or followed the APA program for 6 months (m6). Body composition, MetS parameters, lipid and glucose metabolism markers, inflammatory markers, and a cardiopulmonary exercise test (CPET) were assessed at m0, m6, and after a 3-month wash-out period (m9). Results: After 6 months of intervention, we did not observe variable changes in body weight, body composition, lipid and glucose metabolism markers, inflammatory parameters, or quality of life scores between the four groups. However, during the CPET, the maximal power (Pmax and Ppeak), power, and O₂ consumption at the ventilatory threshold (P(VT) and O₂(VT)) were improved in the APA and ALs+APA groups (p < 0.05), as well as the forced vital capacity (FVC). Between m6 and m9, a gain in fat mass was only observed in patients in the APA and ALs+APA groups. Conclusion: In our randomized controlled trial, arginine and leucine supplementation failed to improve MetS in patients with obesity, as did the supervised adapted physical activity program and the combination of both. Only the cardiorespiratory parameters were improved by exercise training.