Single cell layered heart: electromechanical properties of the heart of Boltenia ovifera

The heart of Boltenia ovifera (the sea potato) is a tubular structure formed by a single layer of myocardial cells. Electron microscopic studies show that each cell contains a single myofibril located adjacent to the luminal surface of the cell. Electrical and mechanical measurement of a cannulated perfused heart demonstrate that only the luminal membrane is excitabble and elicits contraction on depolarization. Calcium and magnesium exert antagonistic effects on tension, and potassium depolarizes the myocardium and produces contractures when the luminal membrane is exposed to various concentrations of these ions. The extraluminl membrane does not respond electrically or mechanically to calcium magnesium or potassium, and its potential seems to be effectively "clamped" by the luminal membrane. Functionaly, therefore, this heart consists of a single active membrane with the adjacent contractile apparatus.     

Tillage effects on soil properties and wheat cultivars traits

Information regarding the evaluation of tillage effects on soil properties and rainfed wheat (Triticum aestivum L.) cultivars of Iranian fields is not available. Therefore, this research was conducted in Sanandaj (west of Iran) using a randomized complete block design in a split-plot arrangement. Three types of tillage including conventional tillage (moldboard plow to soil depth of 30 cm plus disk harrow twice), minimum tillage (chisel plow to soil depth of 15 cm plus disk harrow once) and no-tillage are assigned to the main plots. Wheat cultivars (Sardari and Azar2) were randomly distributed within the subplots in each tillage system. Results showed that the greatest bulk density and cone index were found in the minimum tillage and no tillage systems. The highest rate of grain yield was obtained in the minimum tillage system. The grain yield of Sardari cultivar (1624.1 kg ha^?1) was significantly greater than that of Azar2 (1572 kg ha^?1). Minimum tillage improved soil physical properties and wheat growth compared with the other tillage systems. No tillage increased microbial biomass carbon and bacteria number in soil compared with the other tillage systems. We conclude that using minimum tillage for Sardari cultivar will be more effective compared with other treatments.     

Soil microbial response to tillage systems and fertilization in a sunflower rhizosphere

Tillage systems and fertilization have important effects on soil microorganism activity. Information regarding the simultaneous evaluation of long-term tillage and fertilization on soil microbial traits in sunflower fields is not available. Therefore, this study was conducted to determine the best tillage and fertilization system for soil microbial parameters. The experimental design was a split plot based on a randomized complete block design with three replications. Main plots consisted of the long-term tillage systems (1999–2011) including: no tillage (NT), minimum tillage (MT) and conventional tillage (CT). Six methods of fertilization, including farmyard manure (N1), compost (N2), chemical fertilizers (N3), farmyard manure + compost (N4); farmyard manure + compost + chemical fertilizers (N5), and control (N6) were arranged in subplots. Results showed that the highest amount of microbial biomass was observed in treatment NTN4. The highest and lowest values of enzyme activities (acid, alkaline phosphatase, urease, dehydrogenase and protease) were found in organic fertilizers + NT and chemical fertilizers + CT plots, respectively. Highest basal and induced respiration values were found for NTN4 treatment. Correlation coefficients between enzyme activity, respiration and microbial biomass carbon were significant.     

Optical measurements of extracellular calcium depletion during a single heartbeat

The impermeant dye antipyrylazo III was used to measure depletion of extracellular calcium and net influx of calcium through the sarcolemma during the cardiac action potential. It was found that calcium entry occurs continuously during the action potential and is under direct control of the membrane potential. The inotropic action of epinephrine is accompanied by increased influx of calcium, while strophanthidin enhances the twitch without altering calcium influx during the action potential.     

Increased Osteogenic Potential of Pre-Osteoblasts on Three-Dimensional Printed Scaffolds Compared to Porous Scaffolds for Bone Regeneration

Background:One of the main challenges with conventional scaffold fabrication methods is the inability to control scaffold architecture. Recently, scaffolds with controlled shape and architecture have been fabricated using 3D-printing. Herein, we aimed to determine whether the much tighter control of microstructure of 3DP PLGA/β-TCP scaffolds is more effective in promoting osteogenesis than porous scaffolds produced by solvent casting/porogen leaching. Methods:Physical and mechanical properties of porous and 3DP scaffolds were studied. The response of pre-osteoblasts to the scaffolds was analyzed after 14 days. Results:The 3DP scaffolds had a smoother surface (R_a: 22 ± 3 µm) relative to the highly rough surface of porous scaffolds (R_a: 110 ± 15 µm). Water contact angle was 112 ± 4° on porous and 76 ± 6° on 3DP scaffolds. Porous and 3DP scaffolds had the pore size of 408 ± 90 and 315 ± 17 µm and porosity of 85 ± 5% and 39 ± 7%, respectively. Compressive strength of 3DP scaffolds (4.0 ± 0.3 MPa) was higher than porous scaffolds (1.7 ± 0.2 MPa). Collagenous matrix deposition was similar on both scaffolds. Cells proliferated from day 1 to day 14 by fourfold in porous and by 3.8-fold in 3DP scaffolds. ALP activity was 21-fold higher in 3DP scaffolds than porous scaffolds. Conclusion:The 3DP scaffolds show enhanced mechanical properties and ALP activity compared to porous scaffolds in vitro, suggesting that 3DP PLGA/β-TCP scaffolds are possibly more favorable for bone formation. Key Words: Alkaline phosphatase, β-tricalcium phosphate, Poly(lactic-co-glycolic) acid copolymer     

Efficiency of Iranian forest industry based on DEA models

Data Envelopment Analysis (DEA) is a mathematical tech-nique to assess relative efficiencies of decision making units (DMUs). The efficiency of 14 Iranian forest companies and forest management units w...     

Effects of Atorvastatin on the Hypertension-Induced Oxidative Stress in the Rat Brain

Background: It is well known that the development of brain oxidative stress is one of the most serious complications of arterial hypertension that evokes brain tissue damage. The aim of this study was to examine the effects of atorvastatin treatment (20 mg/kg/day), as an antioxidant, to prevent the brain tissue oxidative stress in the hypertensive (HTN) rats. Methods: Experiments were performed in four groups of rats (n = 5 each group): sham, sham-treated, HTN and HTN treated. Rats were made HTN by aortic constriction above the renal arteries. After 30 days, rats were slaughtered under deep anesthesia to remove brain hemispheres. After tissue homogenization, enzyme activities of superoxide dismutase (SOD) and catalase (CAT), as well as glutathione (GSH) content and malondialdehyde (MDA) level were determined by biochemical methods. Results: In HTN rats, arterial blood pressure was increased about 40% and brain enzyme activities of SOD and CAT were significantly decreased compared with sham group. Induction of hypertension significantly decreased GSH content and increased MDA level of brain tissue. Treatment with atorvastatin enhanced the activity of SOD and prevented from GSH decrement during hypertension. Conclusion: Based on the findings of this study, treatment with atorvastatin might have saved the brain tissue of HTN rats from hypertension-induced oxidative stress. Key Words: Atorvastatin, Aortic coarctation, Oxidative stress, Hypertension     

Enhanced colonization and pathogenicity of Erwinia amylovora strains transformed with the near‐ubiquitous pEA29 plasmid on pear and apple

Three plasmid‐free strains of Erwinia amylovora, the causal agent of fire blight disease of pome trees, one from Iran, one from Egypt and one from Spain, were transformed with the near‐ubiquitous nonconjugative pEA29 plasmid from a wild‐type strain and characterized. The plasmid‐deficient strains were levan‐ and slime‐positive, motile, chemotaxis‐positive, induced HR on Nicotiana tabacum var. xanthi but produced several‐fold less amylovoran and were weakly pathogenic on pear slices and apple seedlings compared to plasmid‐bearing wild‐type strains. When inoculated onto wounded young apple (cv. Royal Gala) leaves, the plasmid‐free strains labelled with green fluorescent protein gene (gfp) were mainly restricted to the inoculation site at the leaf tips, in contrast to the plasmid‐carrying wild‐type strains that moved into the midrib xylem vessel and colonized the adjacent parenchyma cells. Upon introduction of the transposon‐labelled pEA29 plasmid, amylovoran production, degree of oozing and tissue necrosis on pear slices were significantly elevated in all three strains, whilst the levels of levan and levansucrase declined. Only the strains from Iran and Egypt gained the ability to invade and colonize the young apple leaves following the introduction of pEA29. It is concluded that acquisition of the nonconjugative near‐ubiquitous plasmid may not necessarily confer increasing pathogenicity in all bacterial strains.     

Prevalence of Brucellosis in Horse North-East of Iran

Brucella preferentially infects cattle, swine, sheep, and goats. However, some epidemiological surveys have been carried out to investigate nonruminants, such as horses. Horse brucellosis has been found in clinical cases, but there are few epidemiologic patterns. Between May 2008 and April 2009, a total of 120 horses were screened for brucella infections in Mashhad, Iran, by the rose bengal test and the tube agglutination test. Sera from three horses were found positive by rose bengal test and tube agglutination test, and therefore the prevalence rate was 2.5%. In horses, the highest individual seroprevalence was in an animal kept close under the intensive system, with other animals such as cattle, sheep, and goats. The zoonotic aspects of brucellosis from the horse must, therefore, be considered because the disease is important from a public health standpoint. The present study documents the first serological evidence of Brucella spp. infection in horses in Iran.