Using linear-bilinear models for studying gene expression × treatment interaction in microarray experiments

In microarray experiments, the global and the specific gene expression in the two-way table of gene x treatments (or tissues) can be studied using linear-bilinear models that incorporate the main effects of genes (G), treatment (T), and gene x treatment interaction (G x T). The plot of the first two axes obtained from the singular value decomposition of the bilinear (multiplicative) term of these models (biplot) facilitates the interpretation of the gene expression patterns. In this study, two microarray datasets were used to illustrate how two linear-bilinear models, the additive main effect and multiplicative interaction (AMMI) and the treatment regression model (TREG) and their biplots can be used to determine the overall gene expression pattern across treatments (or tissues) and for specific treatments. Dataset 1 had 5,339 genes and the objective was to identify genes with modified expression during maize (Zea mays) seed development in response to different parental ploidy levels. In Dataset 2, the aim was to study gene expression in 15 tissue samples with different levels of development of breast cancer when compared with the expression of the genes in noninfected tissues. The results from the analyses of Dataset 1 showed that the biplots of the AMMI and TREG models allow identification of subsets of genes and treatments with noncrossover G x T interaction or with important levels of crossover G x T. Results from Dataset 2 showed that the TREG model and its biplot facilitates the identification of genes with high expression in all tumor cells. Also, the TREG biplots allowed identification of subsets of genes with a low level of gene x tissue crossover interaction.     

Closantel缓释剂驱除山羊实验感染肝片吸虫的效果

选用 5只实验感染肝片吸虫山羊进行 Closantel(氯氰碘柳胺 )缓释剂驱虫试验。试验用山羊每只一次性口服肝片吸虫囊蚴 15 0个 ,感染后第 15周随机将山羊分成对照组 (n=2 )和驱虫组 (n=3) ,驱虫组每只羊口服 2丸 Closantel缓释剂 (含 15 .5 % Closantel,每丸 7.6 g) ,每周定时采集颈静脉血和进行粪便检查 ,每月称重 ,试验结束时剖检测量肝重和计数肝内虫体数 ,以驱虫前后山羊的红细胞、白细胞、嗜酸性粒细胞、血清抗体和一氧化氮的变化、体重变化、剖检时肝重 /体重之比、虫卵的变化以及虫体减少率作为衡量驱虫效果的指标。结果表明 ,投药后嗜酸性粒细胞在第 1、2、3周与对照组相比有显著下降 ,其他各项指标与对照组相比虽有一定差异但不显著。虫体减少率为 4 1.2 2 %。提示Closantel缓释剂对驱除实验感染肝片吸虫有一定效果 ,在虫体感染前投药会起到预防作用。     

A retrospective study of clinical signs and epidemiology of chronic valve disease in a group of 207 Dachshunds in Poland

Background

Chronic mitral valve disease is frequently seen in the Dachshund. Dachshunds (n=207) made up 11.73% of the dogs admitted to the Cardiology Service at the Small Animal Clinic, Warsaw University of Life Sciences, Poland (first visits only).

Results

Of these, 35 dogs had no clinically detectable heart disease while 172 had chronic valve disease with the mitral valve affected most often (130 dogs), both mitral and tricuspid valves infrequently (39 dogs) and rarely the tricuspid valve (3 dogs). Males were affected more frequently than females and the average age of dogs with chronic valve disease was 11.9 years for females and 11.3 years for males. A majority of the diseased Dachshunds were classified as ISACHC 2 (79), followed by ISACHC 1 (60). Most frequent clinical signs noted by owners included coughing, exercise intolerance, dyspnea and tachypnea. Heart murmurs were generally louder with increased disease severity; however there were 20 dogs in the ISACHC 1 group with no audible heart murmurs. The most frequent electrocardiographic abnormalities included an increased P wave and QRS complex duration, increased R wave amplitude and tachycardia. With increased disease severity, echocardiography revealed an increase in heart size. A higher ISACHC class was related to increased heart size (based on echocardiography) and increased percentage of patients exhibiting enlargement of both left atrium and left ventricle (based on radiography).

Conclusions

The Dachshund is often affected by chronic mitral valvular disease with a late onset of associated clinical signs and few cardiac complications.     

Detection of the effective refractive index of thermally modified Scots pine by immersion liquid method

The purpose of this study was to determine the effective refractive index of thermally modified Scots pine (Pinus sylvestris L.) wood specimens as a quantitative measure regarding the change of wood density which is due to the thermal modification. The refractive index of thermally modified Scots pine wood was obtained by introducing pine wood powder into an immersion liquid and measuring light backscattering with a homebuilt multifunction spectrophotometer. The present method provides useful information that in principle can be applied, for example, in the optimization of the thermal modification process and inspection of the quality of thermally modified wood.     

The effects of kale (Brassica oleracea ssp. acephala), basil (Ocimum basilicum) and thyme (Thymus vulgaris) as forage material in organic egg production on egg quality

1. In organic egg production, forage material as part of the diet for laying hens is mandatory. The purpose of the present study was to examine the effect of feeding with forage materials including maize silage, herbs or kale on egg production and various egg quality parameters of the shell, yolk colour, egg albumen, sensory properties, fatty acid and carotenoid composition of the egg yolk.

2. A total of 5 dietary treatments were tested for 5 weeks, consisting of a basal organic feed plus 120?g/hen.d of the following forage materials: 1) maize silage (control), 2) maize silage incl. 15?g/kg basil, 3) maize silage incl. 30?g/kg basil, 4) maize silage incl. 15?g/kg thyme, or 5) fresh kale leaves. Each was supplied to three replicates of 20 hens. A total of 300 hens was used.

3. Feed intake, forage intake and laying rate did not differ with treatment, but egg weight and egg mass produced increased significantly with the kale treatment.

4. The egg shell strength tended to be higher with the kale treatment, and egg yolk colour was significantly more red with the kale treatment and more yellow with basil and kale treatments. The albumen DM content and albumen gel strength were lowest with the thyme treatment. By sensory evaluation, the kale treatment resulted in eggs with less sulphur aroma, higher yolk colour score, and more sweet and less watery albumen taste. Furthermore, the eggs of the kale treatment had significantly higher lutein and β-carotene content. Also, violaxanthin, an orange xanthophyll, tended to be higher in kale and eggs from hens receiving kale.

5. In conclusion, forage material, especially basil and kale, resulted in increased egg production and eggs of high and differentiable quality.     

Ecological role of the giant root‐rat (Tachyoryctes macrocephalus) in the Afroalpine ecosystem

Rodents with prevailing subterranean activity usually play an important role in the ecosystems of which they are a part due to the combined effect of herbivory and soil perturbation. This is the case for the giant root‐rat Tachyoryctes macrocephalus endemic to the Afroalpine ecosystem of the Bale Mountains, Ethiopia. We studied the impact of root‐rats on various ecosystem features within a 3.5‐ha study locality dominated by Alchemilla pasture, which represents an optimal habitat for this species, in 2 periods of a year. The root‐rats altered plant species composition, reducing the dominant forb, Alchemilla abyssinica, while enhancing Salvia merjame and a few other species, and reduced vegetation cover, but not the fresh plant biomass. Where burrows were abandoned by root‐rats, other rodents took them over and A. abyssinica increased again. Root‐rat burrowing created small‐scale heterogeneity in soil compactness due to the backfilling of some unused burrow segments. Less compacted soil tended to be rich in nutrients, including carbon, nitrogen and phosphorus, which likely affected the plant growth on sites where the vegetation has been reduced as a result of root‐rat foraging and burrowing.     

Spill‐over of European Bat Lyssavirus Type 1 into a Stone Marten (Martes foina) in Germany

European bat lyssavirus type 1 (EBLV‐1, genotype 5) is known to endemically circulate in insectivorous bat populations in Germany. In August 2001, a rabies suspect stone marten (Martes foina) was found in the city of Burg (Saxony‐Anhalt, Germany) and was sent to the regional veterinary laboratory for routine rabies diagnosis. Whereas brain samples repeatedly tested negative in the fluorescent antibody test for classical rabies virus (genotype 1), the mouse inoculation test and the rabies tissue culture inoculation test yielded positive results. Rabies viral RNA was also detected in the stone marten brain sample both by nested and heminested RT‐PCR specific for the nucleoprotein gene and for the nucleoprotein phosphoprotein junction of rabies virus. The amplification products were sequenced to genotype the isolate. Sequence data obtained from the first‐round RT‐PCR products were analysed and the suspect stone marten isolate was confirmed as a rabies related virus (EBLV‐1a). Phylogenetic comparison with sequences from recent genotype five isolates from Germany and Denmark showed that it was closely related to a previous isolate of EBLV‐1 from a serotine bat in Saxony‐Anhalt obtained in the same year in an area adjacent to the place where the EBLV‐1 infected stone marten was found. Both EBLV‐1 isolates share a 99.5% identity. This is the first report of an EBLV‐1a spill‐over from an insectivorous bat into wildlife in Europe.     

Antiarrhythmic and Electrophysiologic Effects of Flecainide on Acutely Induced Atrial Fibrillation in Healthy Horses

Background

Only few pharmacologic compounds have been validated for treatment of atrial fibrillation (AF) in horses. Studies investigating the utility and safety of flecainide to treat AF in horses have produced conflicting results, and the antiarrhythmic mechanisms of flecainide are not fully understood.

Objectives

To study the potential of flecainide to terminate acutely induced AF of short duration (≥15 minutes), to examine flecainide‐induced changes in AF duration and AF vulnerability, and to investigate the in vivo effects of flecainide on right atrial effective refractory period, AF cycle length, and ventricular depolarization and repolarization.

Animals

Nine Standardbred horses. Eight received flecainide, 3 were used as time‐matched controls, 2 of which also received flecainide.

Methods

Prospective study. The antiarrhythmic and electrophysiologic effects of flecainide were based on 5 parameters: ability to terminate acute pacing‐induced AF (≥15 minutes), and drug‐induced changes in atrial effective refractory period, AF duration, AF vulnerability, and ventricular depolarization and repolarization times. Parameters were assessed at baseline and after flecainide by programmed electrical stimulation methods.

Results

Flecainide terminated all acutely induced AF episodes (n = 7); (AF duration, 21 ± 5 minutes) and significantly decreased the AF duration, but neither altered atrial effective refractory period nor AF vulnerability significantly. Ventricular repolarization time was prolonged between 8 and 20 minutes after initiation of flecainide infusion, but no ventricular arrhythmias were detected.

Conclusions and Clinical Importance

Flecainide had clear antiarrhythmic properties in terminating acute pacing‐induced AF, but showed no protective properties against immediate reinduction of AF. Flecainide caused temporary prolongation in the ventricular repolarization, which may be a proarrhythmic effect.