Mutation fixation in MNNG-treated Haemophilus influenzae as determined by transformation

A transformation assay has been used to follow the fixation of mutations to novobiocin resistance induced by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) in Haemophilus influenzae. Very few mutations are produced by recently treated DNA, but many are produced by the DNA from cells that have been incubated for a time after exposure to MNNG. The time course of this mutation fixation is shown to coincide reasonably well with the time course of semiconservative DNA synthesis, as judged by uptake studies and by isopycnic centrifugation of density-labeled cells. Incubation with bromodeoxyuridine (BrdUrd) during the fixation period decreases the number of mutations that are fixed, showing in another way the importance of DNA synthesis for fixation.Mutations fixed in the presence of BrdUrd are not more sensitive to 313-nm radiation than those fixed in its absence, suggesting that these residual mutations are fixed in the absence of extensive DNA replication. Mutations newly fixed in the absence of BrdUrd are much more sensitive to 313-nm radiation than are the same mutations some cell generations later. This shows that the newly fixed mutations are in a state that is different from their final form, either because they are in regions of DNA with special configurations of the strands or because they are in a region of DNA that is a hybrid between an old, alkylated strand and a new strand with some bases different from normal. The data suggest that it is unlikely that anything like all the mutations that are fixed in H. influenzae arise by direct action of MNNG on the replication fork. Many of the results can be explained in terms of fixation during semiconservative replication of premutational lesions, some of which are initially located some distance from the replication fork. The final yield would then depend on the relative rates of removal of the lesions by repair and of fixation by replication.     

Chronic enhancement of brain oxytocin levels causes enduring anti-aggressive and pro-social explorative behavioral effects in male rats

Oxytocin (OXT) has been implicated in the regulation of social behaviors, including intermale offensive aggression. Recently, we showed that acute enhancement of brain OXT levels markedly suppressed offensive aggression and increased social exploration in resident rats confronted with an intruder in their home territory. Moreover, a different responsivity to the exogenous OXTergic manipulation was observed among individuals based on their baseline aggression. In this study we aimed at evaluating the behavioral response to chronically enhancing or attenuating central OXT levels, and at scrutinizing whether the trait-aggression moderates the treatment-induced behavioral changes. To this end, resident male wild-type Groningen rats were continuously (via osmotic minipumps) intracerebroventricularly infused with synthetic OXT or a selective OXT receptor (OXTR) antagonist for 7 days. Changes in behavior were assessed performing a resident–intruder test before and at the end of the treatment period, as well as after 7 days of withdrawal. Chronic infusion of OXT was found to selectively suppress aggression and enhance social exploration. Chronic blockage of OXTRs instead increased introductory aggressive behavior (i.e. lateral threat), yet without affecting the total duration of the aggression. The magnitude of the anti-aggressive changes correlated positively with the level of baseline aggression. Interestingly, OXT-induced behavioral changes persisted 7 days after cessation of the treatment. In conclusion, these findings provide further evidence that enhanced functional activity of the central OXTergic system decreases social offensive aggression while it increases social explorative behavior. The data also indicate that chronically enhancing brain OXT levels may cause enduring anti-aggressive and pro-social explorative behavioral effects.     

Development of a metabolomic approach based on urine samples and direct infusion mass spectrometry

The analysis of urine by direct infusion mass spectrometry suffers from ion suppression due to its high salt content and inter-sample variability caused by the differences in urine volume between persons. Thus, urine metabolomics requires a careful selection of the sample preparation procedure and a normalization strategy to deal with these problems. Several approaches were tested for metabolomic analysis of urine samples by direct infusion electrospray mass spectrometry (DI–ESI–MS), including solid phase extraction, liquid–liquid extraction, and sample dilution. In addition, normalization of results based on conductivity values and statistical treatment was performed to minimize sample variability. Both urine dilution and solid phase extraction with mixed mode sorbent considerably reduced the salt content in urine, providing comprehensive metabolomic fingerprints. Moreover, statistical data normalization enabled the correction of inter-sample physiological variability, improving the quality of results obtained. Therefore, high-throughput DI–ESI–MS fingerprinting of urine samples can be achieved with simple pretreatment procedures allowing the use of this noninvasive sampling in metabolomics. Finally, the optimized approach was tested in a pilot metabolomic investigation of urine samples from transgenic mice models of Alzheimer’s disease (APP/PS1) in order to illustrate the potential of the methodology.     

Evaluación de la utilización de las prestaciones específicas de los sistemas de infusión subcutánea de insulina y su relación con el control metabólico en pacientes con diabetes tipo 1

Background and objectivePatients with type 1 diabetes (T1DM) treated with continuous subcutaneous insulin infusion (CSII) have available several specific features of these devices. The aim of this study was to evaluate the relationship between real use of them and the degree of glycemic control in patients using this therapy.Patients and methodsForty-four T1DM patients on CSII therapy with or without real-time continuous glucose monitoring (CGM) were included. Data from 14 consecutive days were retrospectively collected using the therapy management software CareLink Personal/Pro^® and HbA1c measurement performed at that period. The relationship between the frequency of usie of specific features of insulin pumps (non-sensor augmented or sensor-augmented) and glycemic control was analyzed.ResultsMean HbA1c in the group was 7.5 ± .8%. Mean daily number of boluses administered was 5.1 ± 1.8, with 75.4% of them being bolus wizards (BW). Daily number of boluses was significantly greater in patients with HbA1c < 7.5% than in those with HbA1c > 7.5% (5.3 ± 1.6 vs. 4.3 ± 1.6, P = .056). There was a trend to greater use of BW in patients with better control (82.8 ± 21.4% vs. 69.9 ± 29.1%, P = .106). HbA1c was lower in patients using CGM (n = 8) as compared to those not using sensor-augmented pumps (7.6 ± .8 vs 7.1 ± .7, P = .067), but the difference was not statistically significant.ConclusionsMore frequent use of BW appears to be associated to better metabolic control in patients with T1DM using pump therapy. In standard clinical practice, augmentation of insulin pump with CGM may be associated to improved glycemic control.     

靶控输注静脉麻醉和腰硬联合麻醉对直肠癌根治术患者免疫功能的 影响研究

目的：探讨靶控输注静脉麻醉和腰硬联合麻醉对直肠癌根治术患者免疫功能的影响。方法：选择在我院行直肠癌根治术的 72 例患者,将其分为观察组和对照组各36 例,其中观察组给予靶控输注静脉麻醉,对照组采用腰硬联合麻醉,对两组患者手术时 间、术中出血量以及免疫球蛋白水平（IgG、IgA、IgM）、血清白介素-6 水平（IL-6）、肿瘤坏死因子-a 水平（TNF-a）以及T 细胞亚群 （CD3、CD4）水平进行对比。结果：观察组手术平均时间为（130.5± 11.7）min,术中平均出血量为（271.3± 37.8）ml,与对照组比较差 异均无统计学意义（P>0.05）;两组IgG、IgA 及IgM,在T1、T2、T3 及T4 时刻水平比较差异均无统计学意义（P>0.05）;两组IL-6、 TNF-a、CD3 及CD4 在麻醉后较T1 时均有明显变化,比较差异均有统计学意义（P<0.05）,且观察组变化较对照组更为明显,两组 比较差异有统计学意义（P<0.05）。结论：靶控输注静脉麻醉和腰硬联合麻醉对直肠癌根治术患者免疫功能均存在抑制作用,且以 抑制细胞免疫功能为主,而腰硬联合麻醉抑制作用较低,值得推广应用。     

Trypanosoma cruzi: effects of infection on cathepsin D activity in the midgut of Rhodnius prolixus

Cathepsin D activity was estimated in midgut homogenates from Rhodnius prolixus, uninfected and experimentally infected with Trypanosoma cruzi, at different times after blood ingestion. No enzyme activity was found in the anterior midgut and rectum. In the posterior midgut, enzyme activity was found both in lumen and wall. In starved uninfected insects, in lumen and wall, cathepsin D activity was high, decreasing to a constant rate at 1-15 days after feeding. In insects infected with T. cruzi cathepsin D activity increased 1 and 3 days after blood meal. We suggest that these changes in cathepsin D activity in R. prolixus posterior midgut are due to the establishment of T. cruzi infection.     

Effects of a seven-day continuous infusion of ropivacaine on circadian rhythms in the rat

The present study was conducted to evaluate the effect of a 7 d continuous infusion of ropivacaine on the 24 h rhythms of body temperature, heart rate, and locomotor activity. After an initial 7 d baseline, rats were randomly divided into two groups of 4 rats each to receive ropivacaine or saline via an osmotic pump for 7 consecutive days. The pumps were removed thereafter and observed during a 7 d recovery span. The studied circadian rhythms were measured by radiotelemetry throughout each of the 7 d periods. An additional group of 4 rats was studied under the same experimental conditions to assess the plasma levels of ropivacaine on days 3 and 8 following pump implantation. Our results indicate that ropivacaine does not induce loss of the circadian rhythms of body temperature, heart rate, or locomotor activity; a prominent period of 24 h was found for all variables in all animals, before, during, and after ropivacaine treatment. However, ropivacaine treatment did modify some characteristics of the rhythms; it increased the MESOR (24 h mean) of the heart rate and locomotor activity rhythms and advanced the acrophase (peak time) of the locomotor activity circadian rhythm. The present study indicates that the circadian rhythms of heart rate and locomotor activity are modified after continuous infusion of ropivacaine, which is of particular interest, given the potential cardiotoxicity of this local anesthetic agent.     

Rapid protein identification using direct infusion nanoelectrospray ionization mass spectrometry

Current protein identification techniques are largely based on MALDI-TOF mass fingerprinting and LC-ESI MS/MS sequence tag analysis. Here we describe an improved method for rapid protein identification that uses direct infusion nanoelectrospray quadrupole time-of-flight (nanoESI QTOF) MS. Protein digests were analyzed without LC separation using nanoESI on a QSTAR XL MS/MS system in information dependent data acquisition mode. The protein identification conditions and parameters were extensively evaluated with in-solution and in-gel digested protein samples. Rapid identification of proteins was achieved and compared directly to the results obtained on the same samples using nanoflow HPLC-MS/MS on the QSTAR system. The increased throughput, reproducibility, the high data quality, and the ease of use make the direct infusion system an efficient and affordable technique for protein identification analysis.     

Trypanosoma cruzi: Biological characterization of lineages I and II supports the predominance of lineage I in Colombia

The causes of the particular distribution of both Trypanosoma cruzi lineages throughout the American continent remain unknown. In Colombia, T. cruzi I is the predominant group in both domestic and sylvatic cycles. Here, we present the biological characterization of T. cruzi parasites belonging to both T. cruzi I and T. cruzi IIb groups. Our results show the inability of the T. cruzi IIb clones to infect mammalian cells, produce trypomastigotes and replicate in Rhodnius prolixus, the main vector species in this country. Moreover, this result was confirmed when other species from the same genus, such as R. pallescens and R. robustus, were infected with the same TcIIb clone and its parental strain, while the infection in other genera such as Triatoma and Panstrongylus was successful. Furthermore, the growth kinetics and duplication time in vitro suggest that the high prevalence of T. cruzi I in Colombia results from more successful interactions between parasite lineage, vector, and host species. This type of study may help to understand the factors influencing the particular epidemiological patterns of Chagas disease transmission in different endemic regions.