Muller's ratchet in a near-critical regime: Tournament versus fitness proportional selection.

Muller's ratchet, in its prototype version, models a haploid, asexual population whose size N is constant over the generations. Slightly deleterious mutations are acquired along the lineages at a constant rate, and individuals carrying less mutations have a selective advantage. The classical variant considers fitness proportional selection, but other fitness schemes are conceivable as well. Inspired by the work of Etheridge et al. (2009) we propose a parameter scaling which fits well to the "near-critical" regime that was in the focus of Etheridge et al. (2009) (and in which the mutation-selection ratio diverges logarithmically as N→∞). Using a Moran model, we investigate the"rule of thumb" given in Etheridge et al. (2009) for the click rate of the "classical ratchet" by putting it into the context of new results on the long-time evolution of the size of the best class of the ratchet with (binary) tournament selection. This variant of Muller's ratchet was introduced in González Casanova et al. (2023), and was analysed there in a subcritical parameter regime. Other than that of the classical ratchet, the size of the best class of the tournament ratchet follows an autonomous dynamics up to the time of its extinction. It turns out that, under a suitable correspondence of the model parameters, this dynamics coincides with the so called Poisson profile approximation of the dynamics of the best class of the classical ratchet.

Mechanical stretch increases L-type calcium channel stability in cardiomyocytes through a polycystin-1/AKT-dependent mechanism.

The L-type calcium channel (LTCC) is an important determinant of cardiac contractility. Therefore, changes in LTCC activity or protein levels could be expected to affect cardiac function. Several studies describing LTCC regulation are available, but only a few examine LTCC protein stability. Polycystin-1 (PC1) is a mechanosensor that regulates heart contractility and is involved in mechanical stretch-induced cardiac hypertrophy. PC1 was originally described as an unconventional Gi/o protein-coupled receptor in renal cells. We recently reported that PC1 regulates LTCC stability in cardiomyocytes under stress; however, the mechanism underlying this effect remains unknown. Here, we use cultured neonatal rat ventricular myocytes and hypo-osmotic stress (HS) to model mechanical stretch. The model shows that the Cavß2 subunit is necessary for LTCC stabilization in cardiomyocytes during mechanical stretch, acting through an AKT-dependent mechanism. Our data also shows that AKT activation depends on the G protein-coupled receptor activity of PC1, specifically its G protein-binding domain, and the associated Gßγ subunit of a heterotrimeric Gi/o protein. In fact, over-expression of the human PC1 C-terminal mutant lacking the G protein-binding domain blunted the AKT activation-induced increase in Cav1.2 protein in cardiomyocytes. These findings provide novel evidence that PC1 is involved in the regulation of cardiac LTCCs through a Gißγ-AKT-Cavß2 pathway, suggesting a new mechanism for regulation of cardiac function.

Poor achievement of guidelines-recommended targets in type 2 diabetes: findings from a contemporary prospective cohort study.

AIMS: To prospectively evaluate diabetes management in the primary care setting and explore factors related to guideline-recommended triple target achievement [blood pressure (BP) ≤ 130/80 mmHg, A1C ≤ 7% and low-density lipoprotein (LDL)-cholesterol < 2.5 mmol/l]. METHODS: Baseline, 6 and 12 month data on clinical and laboratory parameters were measured in 3002 patients with type 2 diabetes enrolled as part of a prospective quality enhancement research initiative in Canada. A generalised estimating equation model was fitted to assess variables associated with triple target achievement. RESULTS: At baseline, 54%, 53% and 64% of patients, respectively, had BP, A1C and LDL-cholesterol at target; all three goals were met by 19% of patients. The percentage of individuals achieving these targets significantly increased during the study [60%, 57%, 76% and 26%, respectively, at the final visit, p < 0.0001 except for A1C, p = 0.27]. A much smaller proportion of patients had adequate control during the entire study period [30%, 39%, 53% and 7%, respectively]. In multivariable analysis, women, patients younger than 65 years and patients of Afro-Canadian origin were less likely to achieve the triple target. DISCUSSION: As part of a quality enhancement research initiative, we observed important improvements in the attainment of guidelines-recommended targets in patients with type 2 diabetes followed for a 12-month period in the primary care setting; however, many individuals still failed to achieve and especially maintain optimal goals for therapy, particularly the triple target. Results of the multivariable analysis reinforce the need to address barriers to improve diabetes care, particularly in more susceptible groups.

The role of connectivity on COVID-19 preventive approaches.

Preventive and modelling approaches to address the COVID-19 pandemic have been primarily based on the age or occupation, and often disregard the importance of heterogeneity in population contact structure and individual connectivity. To address this gap, we developed models based on Erdos-Rényi and a power law degree distribution that first incorporate the role of heterogeneity and connectivity and then can be expanded to make assumptions about demographic characteristics. Results demonstrate that variations in the number of connections of individuals within a population modify the impact of public health interventions such as lockdown or vaccination approaches. We conclude that the most effective strategy will vary depending on the underlying contact structure of individuals within a population and on timing of the interventions.

A haplotype of cyclooxygenase-2 gene is associated with idiopathic pulmonary fibrosis.

BACKGROUND: Cyclooxygenase-2, a key regulatory enzyme in the synthesis of the antifibrotic agent prostaglandin E2, is downregulated in lung tissue from patients with idiopathic pulmonary fibrosis. OBJECTIVE: To investigate the association between COX2.3050 (G --> C), COX2.8473 (C --> T) and COX2.926 (G --> C) single nucleotide polymorphisms (SNP) and the susceptibility to idiopathic pulmonary fibrosis and the progression of the disease. DESIGN: Genetic polymorphisms were analyzed in 121 out of 225 available control subjects and in all of 174 patients with idiopathic pulmonary fibrosis by real time polymerase chain reaction. Logistic regression analysis of covariance and chi-squares test were used for statistical analysis. RESULTS: While analysis of disease development did not find any significant association with single SNP genotype, a haplotype analysis revealed a strong association between the disease development and one haplotype [GC] at loci COX2.3050 and COX2.8473, and suggested a recessive genetic effect of this haplotype. Further analysis concluded that subjects having two copies of [GC] haplotype, or equivalently (GG/CC) genotype at the two SNPs, had an increased risk after adjusting for age and sex. Due to the interaction, this elevated risk increased slowly with age, and the estimated odds ratio (OR) decreased with age from OR = 1.4 at age 30 to OR = 1 at age 74 and OR = 0.96 at age SO. The OR was significantly greater than 1 up to age 66, and not significant for age older than 66. Therefore, the recessive effect of [GC] haplotype increased the risk of IPF of subjects younger than 66 years, but its effect diminished for seniors older than 66. One hundred and forty-nine patients with idiopathic pulmonary fibrosis were followed up for 33.7 +/- 2.1 months. Further analysis of disease progressions, defined by the changes in pulmonary function tests, did not reveal any association with either SNP genotypes or haplotypes. CONCLUSIONS: The carriage of double homozygote (GG/CC) at the SNP loci of COX2.3050 and COX2.8473 polymorphisms may increase the susceptibility to idiopathic pulmonary fibrosis, by approximately 1.4 folds at age 30 and by a smaller fold greater than 1 up to age 66 years, but not the progression of the disease. These findings may help to improve our understanding of idiopathic pulmonary fibrosis pathogenesis and may lead to the development of new therapeutic strategies.

360-Degree evaluation: Towards a comprehensive, integrated assessment of performance on clinical placement in nursing degrees: A descriptive observational study.

BACKGROUND: The assessment of the acquisition of clinical competencies is a critical issue for nursing students. 360-degree evaluations are a widespread practice in professional competency assessment and can be applied to the learning/teaching process of future nurses. OBJECTIVES: To determine the effectiveness of the implementation of a 360-degree evaluation proposal for assessing the competencies acquired by third-year nursing students during their clinical placements. DESIGN: A mixed-methods design was used with a primary component (a cross-sectional descriptive observational design) and a parallel qualitative component. PARTICIPANTS: Sixty-seven third-year nursing students from a public university in Madrid, Spain, who were undertaking their clinical placements during seven weeks in medical/surgical units in hospital settings. METHODS: This study was conducted between September 2017 and May 2018. Quantitative data were obtained using assessment tools specifically developed for this 360-degree evaluation proposal. Qualitative information was collected from two focus groups, one with students and one with teaching staff. A descriptive analysis of the quantitative data was conducted. Qualitative data were studied using a thematic analysis. RESULTS: The mean scores for each of the items in the 360-degree evaluation were high, with the highest grades being observed in the evaluations made by peers and patients (a mean of 9.1 out of 10.0). On average, the 360-degree evaluation method yielded grades 0.067 percentage points higher than did the previous evaluation method (p ≤ 0.001). Students and teaching staff encountered difficulties in the evaluations made by users/families and other members of the healthcare team (nursing assistants and physicians), although they rated the overall proposal as being very powerful in terms of educational value. CONCLUSIONS: The 360-degree evaluation method is an innovative, motivating, and integrating approach to the acquisition of competencies with a focus on excellence.

Recently acquired HIV infection in Spain (2003-2005): introduction of the serological testing algorithm for recent HIV seroconversion.

BACKGROUND: Identification of recent HIV infections provides a description of the current pattern of HIV transmission and, consequently, can help to design better preventive interventions. Our study shows the first implementation in Spain of the Serologic Testing Algorithm for Recent HIV Seroconversion (STARHS) strategy. We assess the viability of introducing STARHS in our setting and describe the frequency and epidemiological characteristics of recent infections (RIs). METHODS: Between 2003 and 2005, HIV-positive blood samples drawn for diagnostic purposes were collected from 28 Spanish laboratories to be tested using STARHS. Samples from patients with a previous HIV diagnosis, age <18 years, <200 CD4 cells/microL or clinical AIDS criteria were excluded from the analysis. RESULTS: A total of 660 (19.2%) samples were classified as RI. Most people identified with RI were male (79.8%) with a median age of 33.1 years, and 62.5% occurred among men who have sex with men (MSM). Immigrants made up 26.5% of individuals identified with RIs, with 48.7% coming from South America. Among the individuals with RI, at least 16.5% had reported another sexually transmitted infection (STI) during the year before the HIV diagnosis. CONCLUSION: The study shows that the implementation of STARHS in our setting is feasible and has highlighted important features of the local HIV epidemic, such as the ongoing spread of HIV among MSM, the potential role of STIs in RIs and the vulnerability of immigrants as a new target population.

Lymphangioleiomyomatosis: a study of 72 patients from the Spanish registry.

BACKGROUND: Pulmonary lymphangioleiomyomatosis (LAM) is a rare lung disease that almost exclusively affects young women of childbearing age. The true incidence and prevalence of LAM are unknown. This study was conducted to evaluate the characteristics of lymphangioleiomyomatosis in Spain. METHODS: Over a 2-year period, a questionnaire designed for this study was collected. This questionnaire included sociodemograhic, clinical, radiological and functional data. Information about the study and this questionnaire were both sent by e-mail to all the participants of the interstitial disease registry of 2004. RESULTS: Seventy-two patients, all of whom were women, were included in the registry, with a mean age of 44.56 +/- 11.1 yr. Sixty-three patients (87.5%) presented the sporadic LAM and 9 (12.5%) presented LAM associated with tuberous sclerosis (LAM-TS). LAM diagnosis was confirmed with an open lung biopsy in 57 patients (79.2%) and was performed with thoracic HRCT compatible with LAM diagnosis in the other 15 cases. The most frequent symptom was dyspnoea (90%) followed by cough (44.4%). Almost 40% of patients presented renal angiomyolipomas in the study and the most frequent spirometric pattern was obstructive in more than half of the patients. Most patients with LAM-TS (88.8%) had renal angiomyolipomas compared with 31.7% in the sporadic LAM group. CONCLUSION: The characteristics of the Spanish population affected with LAM are similar to those of other countries. Most patients were symptomatic, had a history of previous pneumothorax and presented abnormal radiological findings and pulmonary function tests.

Angiotensinogen gene G-6A polymorphism influences idiopathic pulmonary fibrosis disease progression.

Angiotensin II is a growth factor that plays a key role in the physiopathology of idiopathic pulmonary fibrosis (IPF). A nucleotide substitution of an adenine instead of a guanine (G-6A) in the proximal promoter region of angiotensinogen (AGT), the precursor of angiotensin II, has been associated with an increased gene transcription rate. In order to investigate whether the G-6A polymorphism of the AGT gene is associated with IPF development, severity and progression, the present study utilised a case-control study design and genotyped G-6A in 219 patients with IPF and 224 control subjects. The distribution of G-6A genotypes and alleles did not significantly differ between cases and controls. The G-6A polymorphism of the AGT gene was not associated with disease severity at diagnosis. The presence of the A allele was strongly associated with increased alveolar arterial oxygen tension difference during follow-up, after controlling for the confounding factors. Higher alveolar arterial oxygen tension changes over time were observed in patients with the AA genotype (0.37+/-0.7 mmHg (0.049+/-0.093 kPa) per month) compared to GA genotype (0.12+/-1 mmHg (0.016+/-0.133 kPa) per month) and GG genotype (0.2+/-0.6 mmHg (0.027+/-0.080 kPa) per month). G-6A polymorphism of the angiotensinogen gene is associated with idiopathic pulmonary fibrosis progression but not with disease predisposition. This polymorphism could have a predictive significance in idiopathic pulmonary fibrosis patients.

Association of the 3050G>C polymorphism in the cyclooxygenase 2 gene with systemic sarcoidosis.

BACKGROUND: We investigated the potential association between cyclooxygenase-2 (COX-2) gene polymorphisms and clinical manifestations of sarcoidosis. METHODS: This observational cross-sectional study involved seven hospitals in Spain. We diagnosed patients with sarcoidosis according to the International Criteria. The following variables were recorded: age, gender, initial diagnostic methods, serum angiotensin-converting enzyme (ACE) levels, pulmonary function tests, radiological stage, and clinical findings at diagnosis. Manifestations of sarcoidosis were classified as systemic vs. nonsystemic. Genotyping of four COX-2 polymorphisms (COX2.5909T>G, COX2.8473T>C, COX2.926G>C, and COX2.3050G>C) was undertaken on DNA extracted from peripheral blood lymphocytes using fluorescent hybridization probes and melting curves. RESULTS: A total of 131 sarcoid patients (63 males, mean age: 47 +/- 15 years) were studied. One hundred twenty-six of these patients had one or more positive biopsies. The results demonstrated that genotype distribution for the COX2.3050G>C polymorphism was significantly different between patients with systemic sarcoidosis and those with nonsystemic forms (p = 0.046). After adjustment for age, gender, and serum ACE levels, a significant association between the carriage of at least one C allele of the COX2.3050G>C polymorphism and systemic sarcoidosis was observed (odds ratio [OR]: 2.3; 95% confidence interval [CI]: 1.03-5.12, p = 0.031). Other polymorphisms were not associated with either clinical manifestations of the disease or serum ACE levels. CONCLUSIONS: Our results indicate for the first time that the C allele of the COX2.3050G>C polymorphism is associated with systemic sarcoidosis.

Nanowire based bioprobes for electrical monitoring of electrogenic cells.

The continuous miniaturization of electronic components and the emergence of nano-biotechnology has opened new perspectives to monitor electrical activities at the single cell level. Here, we describe the creation of very high surface-to-volume ratio passive devices (vertical nanowire probes) using large-scale fabrication process, allowing to follow the electrical activity of mammalian neurons. Based on conventional silicon processing, the silicon nanowires were silicided in platinum in order to improve their electrochemical performances and to guarantee their biocompatibility. Very high signal to noise ratio was achieved (up to 2000) when measuring spontaneous action potentials. Moreover, this bio-platform was used to record the impact of various bio-chemical and electrical stimulations on neuronal activity. To conclude, this study proposes a thorough comparison of the characteristics and performances of these new nanowire-based nanoprobes with the main alternative systems published up to now.

Preliminary results of treatment with pegylated interferon alpha 2A for chronic hepatitis C virus in kidney transplant candidates on hemodialysis.

INTRODUCTION: At present, there is little published information on the outcome of treatment with pegylated interferon (Peg-IF alpha 2a) in hepatitis C virus (HCV)-infected hemodialysis patients awaiting renal transplantation. The objective of this study was to assess the efficacy and tolerance of Peg-IF alpha 2a in this population. PATIENTS AND METHODS: Twelve noncirrhotic HCV-infected patients (10 men, 50 +/- 8 years of age, genotype 1b 84%), were prescribed Peg-IF alpha 2a, at 135 microg/wk for 48 weeks. Liver biopsy was performed in 11 of 12 cases. RESULTS: Six patients completed 48 weeks of treatment, with one end of treatment response (ETR), two sustained viral responses (SVRs), and three HCV relapses. Treatment was shorter in the six remaining patients: two cases 24 weeks (one due to medical reasons with relapse, one due to nonresponse), one patient chose to discontinue at 14 weeks (with relapse), one patient died of stroke at 10 weeks, and in two additional patients interferon was withdrawn at 18 weeks because of severe anemia (SVR) and at 26 weeks due to prolonged fever (relapse). Other secondary treatment-related events included anemia (requiring transfusion in two patients and major erythropoietin administration in six), and fever in four patients. CONCLUSIONS: Peg-IF had limited efficacy in this group, with ETR in 83%, SVR in only 25%, and recurrence in 50%. Tolerance was moderate, with 4/12 (33%) discontinuing treatment due to adverse events, personal decision, or death. Large randomized controlled studies are needed to determine the role of Peg-IF treatment in this population.

Quantification of the overall measurement uncertainty associated with the passive moss biomonitoring technique: Sample collection and processing.

In this study we examined 6080 data gathered by our research group during more than 20 years of research on the moss biomonitoring technique, in order to quantify the variability generated by different aspects of the protocol and to calculate the overall measurement uncertainty associated with the technique. The median variance of the concentrations of different pollutants measured in moss tissues attributed to the different methodological aspects was high, reaching values of 2851 (ng·g-1)2 for Cd (sample treatment), 35.1 (µg·g-1)2 for Cu (sample treatment), 861.7 (ng·g-1)2 and for Hg (material selection). These variances correspond to standard deviations that constitute 67, 126 and 59% the regional background levels of these elements in the study region. The overall measurement uncertainty associated with the worst experimental protocol (5 subsamples, refrigerated, washed, 5 × 5 m size of the sampling area and once a year sampling) was between 2 and 6 times higher than that associated with the optimal protocol (30 subsamples, dried, unwashed, 20 × 20 m size of the sampling area and once a week sampling), and between 1.5 and 7 times higher than that associated with the standardized protocol (30 subsamples and once a year sampling). The overall measurement uncertainty associated with the standardized protocol could generate variations of between 14 and 47% in the regional background levels of Cd, Cu, Hg, Pb and Zn in the study area and much higher levels of variation in polluted sampling sites. We demonstrated that although the overall measurement uncertainty of the technique is still high, it can be reduced by using already well defined aspects of the protocol. Further standardization of the protocol together with application of the information on the overall measurement uncertainty would improve the reliability and comparability of the results of different biomonitoring studies, thus extending use of the technique beyond the context of scientific research.

Clindamycin vs penicillin for anaerobic lung infections. High rate of penicillin failures associated with penicillin-resistant Bacteroides melaninogenicus.

Thirty-seven adult patients with anaerobic lung infections (27 lung abscesses and 10 necrotizing pneumonias) were submitted to transthoracic needle-aspiration and/or bronchoscopic specimen brush cultures before therapy and thereafter in all cases considered to be failures. Patients were randomly assigned to receive either clindamycin, 600 mg intravenously every 6 hours, or penicillin G, 2 million U every 4 hours for no less than 8 days, until clinical and radiological improvement became apparent. Treatment was continued orally with clindamycin, 300 mg every 6 hours, or penicillin V, 750 mg every 6 hours, until completing a minimum of 4 weeks. Ten of the 47 anaerobes initially isolated from the lung (nine Bacteroides melaninogenicus and one Bacteroides capillosus) were resistant to penicillin, but none were resistant to clindamycin. Five of the nine patients harboring these penicillin-resistant Bacteroides received penicillin, and all failed to respond to therapy. Overall, eight of the 18 patients in the penicillin group and one of 19 in the clindamycin group failed to respond to therapy. These drugs were equally well tolerated in both groups. The presence of penicillin-resistant Bacteroides is a frequent cause of penicillin failure in patients with anaerobic lung infections. In this setting, clindamycin appears to be the current therapy of choice for initial treatment.

Thrice-weekly cotrimoxazole is better than weekly dapsone-pyrimethamine for the primary prevention of Pneumocystis carinii pneumonia in HIV-infected patients.

OBJECTIVE: To compare the efficacy and safety of two intermittent regimens for the simultaneous primary prevention of Pneumocystis carinii pneumonia (PCP) and toxoplasmosis in HIV-infected patients. DESIGN: Prospective randomized open trial. SETTING: HIV outpatient clinic of an Infectious Disease Service and a 1000-bed university teaching hospital. PATIENTS: A total of 166 HIV-infected patients with a CD4 cell count < 200 x 10(6)/l or a CD4 percentage < 20%, without previous PCP or toxoplasmosis. INTERVENTION: Patients were randomized to oral (1) cotrimoxazole [160 mg trimethoprim (TMP) and 800 mg sulphamethoxazole (SMX)] twice a day on Mondays, Wednesdays and Fridays (n = 81), or (2) dapsone (100 mg) plus pyrimethamine (25 mg) (DP) once a week (n = 85). MAIN OUTCOME MEASURES: Clinical and biological evaluation was performed every 30-60 days. End-points were PCP, toxoplasmosis and death. Adverse reactions were considered as defined in the protocol. RESULTS: After a mean follow-up of 380 days, intention-to-treat analysis revealed that DP patients had a higher rate of PCP [13 out of 85 (15.2%) versus three out of 81 (3.7%); P = 0.01]. The cumulative rates of PCP at 12 and 24 months were 5 and 42% for DP patients and 3 and 10% for TMP-SMX patients, respectively (Mantel-Cox, P = 0.0007). Of the 29 patients who died during follow-up, 14 were in the TMP-SMX group and 15 in the DP group (not significant). Two patients in the TMP-SMX group and three in the DP group developed toxoplasmosis (not significant). Adverse reactions were common (66.7% of TMP-SMX patients and 42.4% of DP patients; P = 0.001). However, only 12.3% of TMP-SMX patients and 2.3% of DP patients (P = 0.01) had to discontinue therapy because of toxicity. CONCLUSIONS: At the given doses, DP was inferior to TMP-SMX in preventing first episodes of PCP. Although more patients and a longer follow-up are required, the regimens appeared to prevent toxoplasmosis equally well.

Expression of synaptosomal-associated protein SNAP-25 in endocrine anterior pituitary cells.

A growing body of evidence indicates that the fundamental molecular mechanism of exocytosis in the secretory pathway may be structurally similar in all eukaryotic cells. The synaptosomal-associated protein of 25 kDa (SNAP-25) is a plasma membrane protein involved in regulated exocytosis in neurons. In order to compare exocytotic components in neurons and endocrine cells, we have analyzed the expression of SNAP-25 in the rat anterior pituitary. Western blotting analysis documented the presence of SNAP-25 in anterior pituitary homogenates and cultured anterior pituitary cells. In addition to SNAP-25, other neuronal proteins involved in exocytosis (syntaxin, VAMP/synaptobrevin and Rab3A) were also detected in the anterior pituitary. The specific expression of SNAP-25 mRNA in anterior pituitary cells was also corroborated by Northern analysis. SNAP-25 immunoreactivity was located at the plasma membrane of endocrine anterior pituitary cells. Characteristically, patches of fine punctate deposits exhibited intense SNAP-25 immunoreactivity. Double-labeling immunocytochemistry revealed that SNAP-25 was mainly associated with gonadotroph cell populations. Furthermore, we demonstrate that in the anterior pituitary, SNAP-25 is selectively cleaved by clostridial neurotoxins. In conclusion, our results establish the presence of SNAP-25 in secretory anterior pituitary cells and suggest a potential role of this protein in the secretion of adenohypophysial hormone.

A combination of interleukin-2 and 60 nm cationic supramolecular biovectors for the treatment of established tumours by subcutaneous or intranasal administration.

The Supramolecular Biovector (SMBV) KY is a drug delivery nanocarrier which consists of a discretely sized, ionically charged, cross-linked polysaccharide core surrounded by a lipid membrane. We used the non-immunogenic spontaneous mammary adenocarcinoma TS/A tumour to test the efficacy on tumour growth of low (10(4) IU) or ultra-low (10(3) IU) doses of interleukin-2 (IL-2) adsorbed to these 60 nm cationic synthetic particles. In comparison with the progressive growth of TS/A cells in syngeneic mice, KY/IL-2 particles coinjected with TS/A cells or administered at a distance from the tumour, inhibited tumour growth while free IL-2, even at 10-100 times the dose used in the KY/IL-2 formulations, had no effect. Studies performed on implanted tumours (treatment at day 6 (D6)) showed that KY/IL-2 administered subcutaneously (s.c.) at five sites distant from the tumour (10(3) IL-2 IU per site) induced rejection of the implanted tumours. Six out of 10 mice were cured while the other four had residual tumours only. In the same experiment, free IL-2 induced only tumoral growth reduction. Protection induced by KY/IL-2 administered s.c. at five sites involved recruitment of a CD8(+) T cell response since nu/nu mice and CD8-depleted mice did not reject the tumours. Mice cured were protected significantly to completely against a rechallenge with TS/A tumour cells, and a systemic tumour-specific CTL activity was induced. Finally, we showed that repeated intranasal (i.n.) administration of KY/IL-2 (low-dose) also led to complete regression of pre-established tumours and partial protection from tumour rechallenge. We therefore suggest that, in contrast to free IL-2, a KY/IL-2 formulation could be used as a systemic immunostimulant leading to the eradication of non-immunogenic, established tumours.

Depolarization-induced release of ATP from cholinergic synaptosomes is not blocked by botulinum toxin type A.

We report here the effects of Botulinum Toxin type A on the release of ATP and Acetylcholine from Torpedo electric organ synaptosomes. Our results show that Botulinum Toxin type A inhibits specifically the K(+)-induced release of Acetylcholine from synaptosomes without affecting the release of ATP. Membrane potential and calcium uptake into cholinergic nerve terminals are not modified after Botulinum Toxin poisoning. It is suggested that either most of the ATP released during the depolarization of the cholinergic synaptosomes does not originate from cholinergic synaptic vesicles or that there are two populations of synaptic vesicles, Acetylcholine-enriched synaptic vesicles and ATP-enriched synaptic vesicles. However, the possibility that the ACh and ATP released could come from different intrasynaptosomal compartments cannot be excluded.

tRNA genes were found in Piscirickettsia salmonis 16S-23S rDNA spacer region (ITS).

Piscirickettsia salmonis is the etiological agent of Salmonid Rickettsial Septicemia, a disease affecting salmon aquaculture industry. We analyzed the 16S-23S rDNA spacer region (internal transcribed spacer, ITS) of Chilean P. salmonis isolates LF-89 and EM-90. Two main ITS amplification products were obtained by PCR using L1 and G1 primers, differing from that described where only one ITS region was found. By Southern blot, it was established that these two amplification products contained sequences related to P. salmonis ITS. Sequence analysis confirmed that P. salmonis had two ITS regions: ITS A and ITS B. In both isolates, the smaller (ITS B) corresponded to ITS sequences previously described for each one, and the larger (ITS A) were almost the same as their respective ITS B sequences interrupted by an insert which contained two tRNAs genes: tRNA-Ile and tRNA-Ala.

Botulinum toxin type A inhibits Ca(2+)-dependent transport of acetylcholine in reconstituted giant liposomes made from presynaptic membranes from cholinergic nerve terminals.

Giant liposomes were made from a mixture of asolectin phospholipid vesicles and presynaptic plasma membranes isolated from Torpedo cholinergic nerve endings. Acetylcholine filled giant liposomes were able to release neurotransmitter upon stimulation by the Ca2+ ionophore A23187 and Ca2+. Botulinum neurotoxin type A inhibited this Ca(2+)-dependent acetylcholine transport. Additionally, Botulinum toxin type A decreased membrane fluidity of liposomes. These results suggest that Botulinum toxin can interact directly with components of the presynaptic plasma membrane and inhibit acetylcholine translocation. Furthermore, since the reconstituted liposomes do not have synaptic vesicle components, the observed effects may account for the action of Botulinum toxin on the non-quantal release of acetylcholine from motor nerve terminals.