Impaired skeletal muscle microcirculation in systemic sclerosis

Introduction

Muscle symptoms in systemic sclerosis (SSc) may originate from altered skeletal muscle microcirculation, which can be investigated by means of blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI).

Methods

After ethics committee approval and written consent, 11 consecutive SSc patients (5 men, mean age 52.6 years, mean SSc disease duration 5.4 years) and 12 healthy volunteers (4 men, mean age 45.1 years) were included. Subjects with peripheral arterial occlusive disease were excluded. BOLD MRI was performed on calf muscles during cuff-induced ischemia and reactive hyperemia, using a 3-T whole-body scanner (Verio, Siemens, Erlangen, Germany) and fat-suppressed single-short multi-echo echo planar imaging (EPI) with four different effective echo times. Muscle BOLD signal time courses were obtained for gastrocnemius and soleus muscles: minimal hemoglobin oxygen saturation (T2*_min) and maximal T2* values (T2*_max), time to T2* peak (TTP), and slopes of oxygen normalization after T2* peaking.

Results

The vast majority of SSc patients lacked skeletal muscle atrophy, weakness or serum creatine kinase elevation. Nevertheless, more intense oxygen desaturation during ischemia was observed in calf muscles of SSc patients (mean T2*_min -15.0%), compared with controls (-9.1%, P = 0.02). SSc patients also had impaired oxygenation during hyperemia (median T2*_max 9.2% vs. 20.1%, respectively, P = 0.007). The slope of muscle oxygen normalization was significantly less steep and prolonged (TTP) in SSc patients (P<0.001 for both). Similar differences were found at a separate analysis of gastrocnemius and soleus muscles, with most pronounced impairment in the gastrocnemius.

Conclusions

BOLD MRI demonstrates a significant impairment of skeletal muscle microcirculation in SSc.     

Anatomical responses of leaves of Black Locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.) to urban pollutant gases and climatic factors

This study investigates responses in the leaf anatomy of Black Locust (Robinia pseudoacacia L.) to the atmospheric pollutants, SO₂, NO₂ and O₃ and climate in Tehran. The anatomical variables studied include thickness of the leaf lamina and of its main constituent tissues and the length and density of stomata. We present evidence that, in response to urban air pollution, the spongy mesophyll layer is thinner, the upper cuticle of the leaf thicker and stomatal density and the ratio of palisade parenchyma to spongy parenchyma are increased. Similar responses were also detected in relation to a climatic gradient. Stomatal density and thickness of the leaf lamina and of its mesophyll layer were all higher under warmer drier conditions. This overlap in anatomical response to two very different suites of environmental variables may reflect a functional overlap between mechanisms designed to restrict water loss in dry climates and those that minimize the uptake of toxic gases in polluted habitats.     

Genotyping of Acanthamoeba isolates from clinical and environmental specimens in Iran

In this study, 15 Acanthamoeba isolates from AK patients and 10 environmental samples (water, soil and animal-origin samples) were classified at the genotype level based on the sequence analysis of the Diagnostic Fragment 3 (DF3) of Acanthamoeba small subunit rRNA gene. The obtained results revealed that most of these Acanthamoeba strains belonged to genotype T4 both in clinical and environmental samples. The presence T11 genotype in clinical samples was also revealed after the genotyping analysis and to our knowledge this is the first report of T11 genotype in Iran. Moreover, the isolation of T4 genotype from cow faeces in this study highlights a possible transmission of Acanthamoeba through animal faeces in Iran.Overall, the widespread distribution of pathogenic Acanthamoeba T4 across the environmental sources and the increasing number of contact lens wearers in Iran, demands more awareness within the public and health professionals as this pathogen is emerging as a risk for human health in Iran and worldwide.     

A multi-enzyme model for Pyrosequencing

Pyrosequencing is a DNA sequencing technique based on sequencing-by-synthesis enabling rapid real-time sequence determination. This technique employs four enzymatic reactions in a single tube to monitor DNA synthesis. Nucleotides are added iteratively to the reaction and in case of incorporation, pyrophosphate (PPi) is released. PPi triggers a series of reactions resulting in production of light, which is proportional to the amount of DNA and number of incorporated nucleotides. Generated light is detected and recorded by a detector system in the form of a peak signal, which reflects the activity of all four enzymes in the reaction. We have developed simulations to model the kinetics of the enzymes. These simulations provide a full model for the Pyrosequencing four-enzyme system, based on which the peak height and shape can be predicted depending on the concentrations of enzymes and substrates. Simulation results are shown to be compatible with experimental data. Based on these simulations, the rate-limiting steps in the chain can be determined, and K_M and k_cat of all four enzymes in Pyrosequencing can be calculated.     

The role of alternative oxidase in modulating carbon use efficiency and growth during macronutrient stress in tobacco cells

When wild-type (wt) tobacco (Nicotiana tabacum cv. Petit Havana SR1) cells are grown under macronutrient (P or N) limitation, they induce large amounts of alternative oxidase (AOX), which constitutes a non-energy-conserving branch of the respiratory electron transport chain. To investigate the significance of AOX induction, wt cells were compared with transgenic (AS8) cells lacking AOX. Under nutrient limitation, growth of wt cell cultures was dramatically reduced and carbon use efficiency (g cell dry weight gain g(-1) sugar consumed) decreased by 42-63%. However, the growth of AS8 was only moderately reduced by the nutrient deficiencies and carbon use efficiency values remained the same as under nutrient-sufficient conditions. As a result, the nutrient limitations more severely compromised the tissue nutrient status (P or N) of AS8 than wt cells. Northern analyses and a comparison of the mitochondrial protein profiles of wt and AS8 cells indicated that the lack of AOX in AS8 under P limitation was associated with increased levels of proteins commonly associated with oxidative stress and/or stress injury. Also, the level of electron transport chain components was consistently reduced in AS8 while tricarboxylic acid cycle enzymes did not show a universal trend in abundance in comparison to the wt. Alternatively, the lack of AOX in AS8 cells under N limitation resulted in enhanced carbohydrate accumulation. It is concluded that AOX respiration provides an important general mechanism by which plant cells can modulate their growth in response to nutrient availability and that AOX also has nutrient-specific roles in maintaining cellular redox and carbon balance.     

Effect of polymer/nanosilver composite packaging on long-term microbiological status of Iranian saffron (Crocus sativus L.)

Crocus sativus L. (saffron) is a valuable plant which is native to Iran. Saffron is the dried stigmata of the flowering part of the plant that is usually contaminated with different bacteria and fungi through production process. Antimicrobial properties of silver nanoparticles are well recognized. To survey the effects of nanosilver packaging on microbiological status of spiked, saffron samples over a six month period were chosen. Saffron samples from five regions of Khorasan province were purchased and de novo frequencies of microbial contaminants were determined using standard procedures. Totally 35 g of saffron was spiked with known numbers of four bacterial and two fungal species and packaged into one gram packets. The packaging materials consisted of polyethylene polymers containing 0, 400, 800, 1200 or 4000 ppm nanosilver (as Ag). Total and differential numbers of spiked microorganisms in the packaged saffrons were enumerated at initial and at six time points of seven, 14, 28, 64, 90 and 180 days. Baird-Parker agar (BP agar), Kenner Fecal (KF), Salmonella–Shigella agar (SS agar), Violet Red Bile Glucose Agar (VRBGA), and Sabouraud Dextrose agar (SD agar) media were used for enumeration of the six spiked microorganisms including Staphylococcus aureus, Enterococcus faecalis, Salmonella Enteritidis, Enterobacter species and Escherichia coli, Fusarium oxysporum and Aspergillus flavus, respectively. Direct antibacterial activity of the composites was also determined. De novo frequencies of microorganisms in five saffron samples were at acceptable levels with dominance of fungi species. Nanosilver embedded packages accelerated the reduction in live microbial numbers in saffron samples and the efficacy was the best in packages containing 4000 ppm nanosilver particles. Nanosilver packaging can significantly reduce microbial burden of saffron.     

Changes in plant mitochondrial electron transport alter cellular levels of reactive oxygen species and susceptibility to cell death signaling molecules

Transgenic tobacco (Nicotiana tabacum) lacking mitochondrial alternative oxidase (AOX) have been compared with wild-type (Wt) tobacco using two different systems, either suspension cell cultures or leaves. In both systems, a lack of AOX was accompanied by an increase in some anti-oxidant defenses, consistent with the hypothesis that a lack of AOX increases the mitochondrial generation of reactive oxygen species (ROS). In most cases, this increase in anti-oxidant defenses could more than offset the presumed increased rate of ROS generation, resulting paradoxically in a lower steady-state level of ROS than was found in Wt leaves or suspension cells. We also found that the amount of cell death induced by salicylic acid or nitric oxide correlated strongly with the level of ROS (irrespective of the level of AOX), while death induced by azide was dependent upon the presence or absence of AOX. These results suggest that susceptibility to cell death by signaling molecules (salicylic acid and nitric oxide) is dependent upon the steady-state cellular level of ROS and that AOX levels clearly contribute to this steady state, perhaps by influencing the rate of mitochondrial-generated ROS and hence the cellular level of anti-oxidant defenses.     

Phylogenetic relationships of Old World Brassicaceae from Iran based on nuclear ribosomal DNA sequences

Phylogenetic analysis of 155 nuclear rDNA ITS sequences among them 19 Iranian endemic genera were used to elucidate phylogenetic relationships of Old World Brassicaceae from Iran in the context of the most recent tribal system suggested by Al-Shehbaz et al. [Al-Shehbaz, I.A., Beilstein, M.A, Kellogg, E.A., 2006. Systematics and phylogeny of the Brassicaceae (Cruciferae): an overview. Plant Syst. Evol. 259, 89–120]. Iranian endemic taxa are assigned to 16 clades, 15 of these correspond to recognized tribes. Our data support the recent tribal recognition of Calepina and relatives and further indicate that the Orychophragmus clade (with Conringia planisiliqua and Orychophragmus) may be recognized as a new tribe. Our data also support the inclusion of 13 genera not previously studied, or with unresolved positions in previous phylogenetic analyses in 10 tribes with the tribal assignment given in parentheses: Acanthocardamum (Aethionemeae), Alyssopsis (Camelineae), Anastatica (Malcolmieae), Asperuginoides (Cochlearieae), Camelinopsis (Thlaspideae), Didymophysa (Thlaspideae), Dielsiocharisi (Camelineae), Lachnoloma (Anchonieae), Micrantha (Anchonieae), Noccidium (Camelineae), Octoceras (Euclidieae), Pseudofortuynia (Sisymbrieae) and Streptoloma (Euclidieae). ITS data and morphological characters further indicate that the remaining five genera, i.e., Acanthocardamum, Olimarabidopsis, Brossardia, Noccidium and Zuvanda may be subsumed under Aethionema, Alyssopsis, Noccaea, Capsella and Conringia, respectively. Alyssum, Chorispora, Fibigia and Goldbachia are paraphyletic and Conringia, Malcolmia, Matthiola are polyphyletic taxa.