Evaluation of Cardiovascular Risk Factors in the Wistar Audiogenic Rat (WAR) Strain

Introduction

Risk factors for life-threatening cardiovascular events were evaluated in an experimental model of epilepsy, the Wistar Audiogenic Rat (WAR) strain.

Methods

We used long-term ECG recordings in conscious, one year old, WAR and Wistar control counterparts to evaluate spontaneous arrhythmias and heart rate variability, a tool to assess autonomic cardiac control. Ventricular function was also evaluated using the pressure-volume conductance system in anesthetized rats.

Results

Basal RR interval (RRi) was similar between WAR and Wistar rats (188±5 vs 199±6 ms). RRi variability strongly suggests that WAR present an autonomic imbalance with sympathetic overactivity, which is an isolated risk factor for cardiovascular events. Anesthetized WAR showed lower arterial pressure (92±3 vs 115±5 mmHg) and exhibited indices of systolic dysfunction, such as higher ventricle end-diastolic pressure (9.2±0.6 vs 5.6±1 mmHg) and volume (137±9 vs 68±9 μL) as well as lower rate of increase in ventricular pressure (5266±602 vs 7320±538 mmHg.s-1). Indices of diastolic cardiac function, such as lower rate of decrease in ventricular pressure (-5014±780 vs -7766±998 mmHg.s^-1) and a higher slope of the linear relationship between end-diastolic pressure and volume (0.078±0.011 vs 0.036±0.011 mmHg.μL), were also found in WAR as compared to Wistar control rats. Moreover, Wistar rats had 3 to 6 ventricular ectopic beats, whereas WAR showed 15 to 30 ectopic beats out of the 20,000 beats analyzed in each rat.

Conclusions

The autonomic imbalance observed previously at younger age is also present in aged WAR and, additionally, a cardiac dysfunction was also observed in the rats. These findings make this experimental model of epilepsy a valuable tool to study risk factors for cardiovascular events in epilepsy.     

Physical size of the <Emphasis Type="Italic">S</Emphasis> locus region defined by genetic recombination and genome sequencing in <Emphasis Type="Italic">Ipomoea trifida</Emphasis>, Convolvulaceae

Sporophytic self-incompatibility (SSI) in the genus Ipomoea (Convolvulaceae) is controlled by a single polymorphic S locus. We have previously analyzed genomic sequences of an approximately 300 kb region spanning the S locus of the S ₁ haplotype and characterized the genomic structure around this locus. Here, we further define the physical size of the S locus region by mapping recombination breakpoints, based on sequence analysis of PCR fragments amplified from the genomic DNA of recombinants. From the recombination analysis, the S locus of the S ₁ haplotype was delimited to a 0.23 cM region of the linkage map, which corresponds to a maximum physical size of 212 kb. To analyze differences in genomic organization between S haplotypes, fosmid contigs spanning approximately 67 kb of the S ₁₀ haplotype were sequenced. Comparison with the S ₁ genomic sequence revealed that the S haplotype-specific divergent regions (SDRs) spanned 50.7 and 34.5 kb in the S ₁ and S ₁₀ haplotypes, respectively and that their flanking regions showed a high sequence similarity. In the sequenced region of the S ₁₀ haplotype, five of the 12 predicted open reading frames (ORFs) were found to be located in the divergent region and showed co-linear organization of genes between the two S haplotypes. Based on the size of the SDRs, the physical size of the S locus was estimated to fall within the range 34–50 kb in Ipomoea.     

Gynoecium structure in Sapindales and a case study of Trichilia pallens (Meliaceae)

Journal of Plant Research - Sapindales is a monophyletic order within the malvid clade of rosids. It represents an interesting group to address questions on floral structure and evolution due to a...     

Use of experimental design to investigate biodiesel production by multiple-stage Ultra-Shear reactor

This work presents biodiesel production from soybean oil and bioethanol by multiple-stage Ultra-Shear reactor (USR). The experiments were carried out in the following conditions: reaction time from 6 to 12 min; catalyst concentration from 0.5% to 1.5% by weight of soybean oil; ethanol: soybean oil molar ratio from 6:1 to 10:1. The experimental design was used to investigate the influence of process variables on the conversion in biodiesel. The best ethyl ester conversion obtained was 99.26 wt.%, with ethanol:soybean oil molar ratio of 6:1, catalyst concentration of 1.35% and with 12 min of reaction time.     

Simulation of integrated first and second generation bioethanol production from sugarcane: comparison between different biomass pretreatment methods

Sugarcane bagasse is used as a fuel in conventional bioethanol production, providing heat and power for the plant; therefore, the amount of surplus bagasse available for use as raw material for second generation bioethanol production is related to the energy consumption of the bioethanol production process. Pentoses and lignin, byproducts of the second generation bioethanol production process, may be used as fuels, increasing the amount of surplus bagasse. In this work, simulations of the integrated bioethanol production process from sugarcane, surplus bagasse and trash were carried out. Selected pre-treatment methods followed, or not, by a delignification step were evaluated. The amount of lignocellulosic materials available for hydrolysis in each configuration was calculated assuming that 50% of sugarcane trash is recovered from the field. An economic risk analysis was carried out; the best results for the integrated first and second generation ethanol production process were obtained for steam explosion pretreatment, high solids loading for hydrolysis and 24–48 h hydrolysis. The second generation ethanol production process must be improved (e.g., decreasing required investment, improving yields and developing pentose fermentation to ethanol) in order for the integrated process to be more economically competitive.     

Pneumococcus: the sugar-coated bacteria.

The study of Streptococcus pneumoniae (the pneumococcus) had been a central issue in medicine for many decades until the use of antibiotics became generalized. Many fundamental contributions to the history of microbiology should credit this bacterium: the capsular precipitin reaction, the major role this reaction plays in the development of immunology through the identification of polysaccharides as antigens, and, mainly, the demonstration, by genetic transformation, that genes are composed of DNA-the finding from the study of bacteria that has had the greatest impact on biology. Currently, pneumococcus is the most common etiologic agent in acute otitis media, sinusitis, and pneumonia requiring the hospitalization of adults. Moreover, meningitis is the leading cause of death among children in developing countries. Here I discuss the contributions that led to the explosion of knowledge about pneumococcus and also report some of the contributions of our group to the understanding of the molecular basis of three important virulence factors: lytic enzymes, pneumococcal phages, and the genes coding for capsular polysaccharides.     

Frequency-dependent baroreflex modulation of blood pressure and heart rate variability in conscious mice

The goal of this study was to determine the baroreflex influence on systolic arterial pressure (SAP) and pulse interval (PI) variability in conscious mice. SAP and PI were measured in C57Bl/6J mice subjected to sinoaortic deafferentation (SAD, n = 21) or sham surgery (n = 20). Average SAP and PI did not differ in SAD or control mice. In contrast, SAP variance was enhanced (21 +/- 4 vs. 9.5 +/- 1 mmHg2) and PI variance reduced (8.8 +/- 2 vs. 26 +/- 6 ms2) in SAD vs. control mice. High-frequency (HF: 1-5 Hz) SAP variability quantified by spectral analysis was greater in SAD (8.5 +/- 2.0 mmHg2) compared with control (2.5 +/- 0.2 mmHg2) mice, whereas low-frequency (LF: 0.1-1 Hz) SAP variability did not differ between the groups. Conversely, LF PI variability was markedly reduced in SAD mice (0.5 +/- 0.1 vs. 10.8 +/- 3.4 ms2). LF oscillations in SAP and PI were coherent in control mice (coherence = 0.68 +/- 0.05), with changes in SAP leading changes in PI (phase = -1.41 +/- 0.06 radians), but were not coherent in SAD mice (coherence = 0.08 +/- 0.03). Blockade of parasympathetic drive with atropine decreased average PI, PI variance, and LF and HF PI variability in control (n = 10) but had no effect in SAD (n = 6) mice. In control mice, blockade of sympathetic cardiac receptors with propranolol increased average PI and decreased PI variance and LF PI variability (n = 6). In SAD mice, propranolol increased average PI (n = 6). In conclusion, baroreflex modulation of PI contributes to LF, but not HF PI variability, and is mediated by both sympathetic and parasympathetic drives in conscious mice.