The influence of positive selection on RAG expression in thymocytes

The expression of recombination activating gene (RAG) products, responsible for T cell receptor (TcR) gene rearrangement, is shut off during positive selection of thymocytes. The precise stage at which this down-regulation occurs remains somewhat controversial. We have analyzed RAG-1 expression in thymocytes of TcR transgenic mice carried on selecting versus non-selecting genetic backgrounds, both by in situ hybridization on thymus sections and by polymerase chain reaction amplification of RNA from sorted cells. The data from several transgenic lines indicate that RAG expression is already reduced in immature, cortical, CD4⁺CD8⁺ cells in the presence of positively selecting major histocompatibility complex molecules, although complete shut-off is not achieved until the mature, medullary, single-positive stage. This finding has practical and theoretical significance for studies on the mechanism of positive selection.     

Organization of the serotoninergic system in the brain of two amphibian species, Ambystoma mexicanum (Urodela) and Typhlonectes compressicauda (Gymnophiona)

An immunocytochemical investigation was made of the distribution of serotonin (5-HT) in the brain of larval and adult Ambystoma mexicanum and adult Typhlonectes compressicauda. Immunoreactive perikarya can be identified in the caudal diencephalon (paraventricular organ and infundibular nucleus), in the ventral mesencephalon (interpeduncular nucleus) and in the raphe of the rhombencephalon. Immunopositive fibers and terminal arborizations are widely distributed, extending from the whole telencephalon to the spinal lemniscus area. However, the retinorecipient structures of the thalamus and mesencephalon are either very weakly innervated (Ambystoma) or completely immunonegative (Typhlonectes). The habenular system also exhibits very few 5-HT-positive structures. The major serotoninergic neuron clusters, in both Urodela and Gymnophiona, tend to gather, from the paraventricular organ to the raphe, on both sides of the sagittal plane, showing no tendency to lateralization. A new interpretation of the limited development of the serotoninergic system in amphibians is given.     

Macroprogestative contraception: advantages

Combined oral contraceptives (OCs) have nearly total efficacy when correctly used and good overall tolerance among most women under 40, but there are several significant contraindications to their use. Women with hypertension, hyperlipidemia, diabetes, minor mastopathy, or premenstrual tension should not use OCs containing estrogen. Macroprogestational OCs administered generally 20 days out of 28 are useful when an antiestrogen effect is sought or when metabolic anomalies are to be avoided. An antiestrogen effect may be desired for women over 40 suffering from relative or absolute hyperestrogenism, or for women with premenstrual syndrome, menorrhagia related to endometrial hyperplasia or other menstrual problems, or benign mastopathies. An antiestrogen effect may also be desired to prevent cellular pathologies common after age 40. Some anomalies of metabolism, blood pressure, and coagulation persist in users of combined OCs regardless of the dose or the compounds used in the formulation. Progestins derived from testosterone were the first to be used in contraception and provide good cycle control and antigonadotropic activity, along with a powerful antiestrogen effect. But they may have metabolic side effects and cause signs of hyperandrogenism. Progestins derived from progesterone have been studied in health women and in those with different risk factors. Chlormadinone acetate has been used in women at high vascular risk, and promegestone has been used in women with fibrocystic breast disorders. A study was also done on 36 healthy women for 6 months using nomegestrol acetate. The preliminary results were good but the numbers of women were small, they had no metabolic risk factors, and the treatment periods were short. The results thus cannot be extrapolated to subjects at risk or for use during longer periods. The only observed modifications (essentially declines in apoprotein A1 and elevation of antithrombine) were probably attributable to the decline in average estradiol levels and without significance for risk. A disadvantage of these methods is that they have not been authorized for marketing as contraceptives in France and no Pearl index is available. Although the incidence of menstrual problems is not well known, such problems appear to be relatively frequent. The hypoestrogenism often sought for women with gynecological pathologies is not necessarily desirable for women using these methods because of metabolic problems or age over 40. A sufficient estradiol level protects against premature bone loss and has important metabolic effects including better production HDL cholesterol. 18 women who experienced menstrual problems with macroprogestational contraceptives were given 5 mg/day of nomegestrol acetate in combination with transdermally administered estradiol. Clinical and metabolic tolerance were excellent, and no pregnancies occurred. Further study is warranted.     

Treatment of patients with advanced non-small cell lung cancer

In advanced non-small cell lung cancer (NSCLC), an objective response to chemotherapy is of limited value and the impact of chemotherapy on survival is modest. Therefore, endpoints evaluating the patients’ subjective benefit such as symptom control (SC), quality of life (QOL) or clinical benefit (CB) have recently been implemented into clinical trials, mostly as secondary endpoints. Chemotherapy offers SC, not only in patients with an objective response, but also in a proportion of patients with disease stabilization. For this purpose, three to four cycles of platinum-based chemotherapy are recommended. Interpretation of QOL objectives is limited by several methodologic problems. Studies comparing best supportive care alone with either older platinum-based combinations or single-agent chemotherapy with a new cytotoxic drug usually indicate improved survival and improvement of some component(s) of QOL in the active treatment arm. However, results from studies comparing different chemotherapies are less definitive. Trials comparing single-agent therapy with a new drug with new combinations mostly report no difference in QOL. In addition, most trials comparing new platinum-based combinations with older ones, and trials comparing new platinum-based regimens fail to show any differences in QOL. As a whole, it is far from clear whether combination therapy is superior to modern single-agent therapy, when the patient’s benefit is the primary endpoint. Non-platinum-based doublets, compared with platinum-based doublets, may lead to slightly inferior survival, are not always less toxic, and have not been proven to provide better QOL outcomes. The CB response, originally reported in pancreatic cancer, measures more than SC, but not full QOL. Encouraging experience with this tool was reported in advanced NSCLC. Randomized studies designed to look at some form of patient benefit as a primary endpoint should be a priority in advanced NSCLC.     

Semimonthly versus monthly regimen of fluorouracil and leucovorin administered for 24 or 36 weeks as adjuvant therapy in stage II and III colon cancer: results of a randomized trial.

PURPOSE: This randomized, 2 x 2 factorial study compared a semimonthly (LVFU2) with a monthly (FULV) regimen of fluorouracil and leucovorin and 24 versus 36 weeks of each regimen as adjuvant treatment of patients with stage II (Dukes' B2) and III (Dukes' C) colon cancer. PATIENTS AND METHODS: LVFU2 was administered semi-monthly for 2 consecutive days as dl- or l-leucovorin (200 or 100 mg/m2, respectively) as a 2-hour infusion, followed by a 400 mg/m2 FU bolus and 600 mg/m2 of FU as a 22-hour continuous infusion. FULV was administered monthly for 5 consecutive days as a 15-minute infusion of dl- or l-leucovorin, followed by 400 mg/m2 of FU as a 15-minute infusion. RESULTS: A total of 905 patients were randomly assigned. The median follow-up was 41 months. Disease-free survival was similar between the LVFU2 and FULV groups (127 v 124 events; hazard ratio [HR] = 1.04; P =.74) and between 24 and 36 weeks of therapy (128 v 123 events; HR = 0.94; P =.63). Analysis of overall survival showed a slight excess in the number of deaths in LVFU2 compared with FULV (73 v 59), but this difference was not statistically significant (HR = 1.26; 95% confidence interval, 0.90 to 1.78; P =.18). The most commonly observed grade 3 to 4 toxicities were neutropenia, diarrhea, and mucositis. Toxicities were significantly lower in the LVFU2 group (all toxicities, P <.001). CONCLUSION: Our data confirm that LVFU2 is less toxic than FULV. At a median follow-up of 41 months, no statistically significant difference could be detected in disease-free or overall survival between the treatment groups or treatment durations.     

Quantitative tumor apoptosis imaging using technetium-99m-HYNIC annexin V single photon emission computed tomography.

PURPOSE: Radiolabeled annexin V may allow for repetitive and selective in vivo identification of apoptotic cell death without the need for invasive biopsy. This study reports on the relationship between quantitative technetium-99m- (99mTc-) 6-hydrazinonicotinic (HYNIC) radiolabeled annexin V tumor uptake, and the number of tumor apoptotic cells derived from histologic analysis. PATIENTS AND METHODS: Twenty patients (18 men, two women) suspected of primary (n = 19) or recurrent (n = 1) head and neck carcinoma were included. All patients underwent a spiral computed tomography (CT) scan, 99mTc-HYNIC annexin V tomography, and subsequent surgical resection of the suspected primary or recurrent tumor. Quantitative 99mTc-HYNIC annexin V uptake in tumor lesions divided by the tumor volume, derived from CT, was related to the number of apoptotic cells per tumor high-power field derived from terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling (TUNEL) assays performed on sectioned tumor slices. RESULTS: Diagnosis was primary head and neck tumor in 18 patients, lymph node involvement of a cancer of unknown primary origin in one patient, and the absence of recurrence in one patient. Mean percentage absolute tumor uptake of the injected dose per cubic centimeter tumor volume derived from tomographic images was 0.0003% (standard deviation [SD], 0.0004%) at 1 hour postinjection (PI) and 0.0001% (SD, 0.0000%) at 5 to 6 hours PI (P =.012). Quantitative 99mTc-HYNIC annexin V tumor uptake correlated well with the number of apoptotic cells if only tumor samples with no or minimal amounts of necrosis were considered. CONCLUSION: In the absence of necrosis, absolute 99mTc-HYNIC annexin V tumor uptake values correlate well with the number of apoptotic cells derived from TUNEL assays.     

Dispositional optimism predicts survival status 1 year after diagnosis in head and neck cancer patients.

PURPOSE: The aim of this study was to investigate the hypothesis that, independent of other known prognostic factors, pessimistic head and neck (H&N) cancer patients have a greater risk of being dead 1 year after diagnosis than do optimistic patients. PATIENTS AND METHODS: A prospective observational study design was used with a cohort of H&N cancer patients diagnosed during the period from March 1, 1997, to August 31, 1998, at the Centre Hospitalier Universitaire, Clermont-Ferrand, France. Dispositional optimism (DO) was evaluated at baseline using a French version of the Life Orientation Test translated and validated for this study. One-year survival status was collected on all subjects. The analysis of the hypothesized association between DO and 1-year survival was performed using multiple logistic regression analysis, controlling for other sociodemographic and clinical variables. RESULTS: The sample size was 101 patients, representing all but one of those patients fitting the inclusion criteria who were diagnosed during the recruitment period. Of these, 51 were alive at 1 year after diagnosis, 45 were dead, and five were lost to follow-up. The multivariate analysis was performed on the data from the 96 subjects in whom 1-year survival status was known. Controlling for known predictors of H&N cancer survival, pessimistic subjects (odds ratio [OR], 1.12; 95% confidence interval [CI], 1.01 to 1.24) and those living alone (OR, 4.14; 95% CI, 1.21 to 14.17) were more likely than optimistic subjects and those living with others to be dead at 1 year. CONCLUSION: The results of this study of a cohort of French H&N cancer patients indicate that dispositional optimism predicts 1-year survival independent of other sociodemographic and clinical variables.     

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.     

Epoxide hydrolases in the rat epididymis: possible roles in xenobiotic and endogenous fatty acid metabolism.

Epoxide hydrolases play an important role in detoxifying epoxides that arise from the metabolism of xenobiotic and endogenous compounds. Both the soluble and microsomal forms of epoxide hydrolase (sEH and mEH, respectively) have been detected in the rat testis. Because of the important role the epididymis plays in sperm maturation and protection, the present study evaluated the presence and activity of these two epoxide hydrolases in the rat epididymis. Using Western blotting, protein bands consistent in size with both mEH and sEH were detected in the caput, corpus, and cauda of the epididymis. The mEH immunoreactive bands in the epididymis ( approximately 50 kDa) were consistent with mEH detected in the liver and kidney. The sEH immunoreactive bands in the epididymis ( approximately 65 kDa) were consistent with a recombinant sEH standard and sEH detected in the liver, kidney, and testis. The presence of mEH and sEH in the epididymis was supported by observations from substrate-based enzyme assays. Results indicated that epididymal mEH can hydrolyze [(3)H]-cis-stilbene oxide to the corresponding diol at levels approximately 9% of the kidney. Epididymal sEH hydrolyzed the substrate [(3)H]-trans-diphenylpropene oxide to the corresponding diol and this activity was inhibited by cyclohexyl-dodecyl urea. Arachidonic acid epoxygenase activity was detected in epididymal S9 fractions, suggesting that fatty acid metabolism by epididymal cytochrome P450s can form epoxides that subsequently become substrates for epididymal sEH. Results from the present study indicate that the epididymis contains at least two active forms of epoxide hydrolase. The role of these enzymes in the detoxification of xenobiotic epoxides is well known, although it is unclear what cellular role they may play in the formation of biologically active metabolites in the epididymis.