Combined computational modeling and experimental analysis integrating chemical and mechanical signals suggests possible mechanism of shoot meristem maintenance

Stem cell maintenance in multilayered shoot apical meristems (SAMs) of plants requires strict regulation of cell growth and division. Exactly how the complex milieu of chemical and mechanical signals interact in the central region of the SAM to regulate cell division plane orientation is not well understood. In this paper, simulations using a newly developed multiscale computational model are combined with experimental studies to suggest and test three hypothesized mechanisms for the regulation of cell division plane orientation and the direction of anisotropic cell expansion in the corpus. Simulations predict that in the Apical corpus, WUSCHEL and cytokinin regulate the direction of anisotropic cell expansion, and cells divide according to tensile stress on the cell wall. In the Basal corpus, model simulations suggest dual roles for WUSCHEL and cytokinin in regulating both the direction of anisotropic cell expansion and cell division plane orientation. Simulation results are followed by a detailed analysis of changes in cell characteristics upon manipulation of WUSCHEL and cytokinin in experiments that support model predictions. Moreover, simulations predict that this layer-specific mechanism maintains both the experimentally observed shape and structure of the SAM as well as the distribution of WUSCHEL in the tissue. This provides an additional link between the roles of WUSCHEL, cytokinin, and mechanical stress in regulating SAM growth and proper stem cell maintenance in the SAM.     

Association of HLA class I antigens and HLA class II alleles with vitiligo in a Turkish population

As is the case with many other autoimmune diseases, there is an association between vitiligo and HLA complex. HLA subtypes vary with racial/ethnic background. The purpose of this study was to determine which HLA class I antigens and HLA class II alleles are associated with Turkish vitiligo patients. Forty-one patients with vitiligo and 61 healthy control subjects were typed for HLA class II alleles. Thirty-three out of 41 patients with vitiligo and 100 healthy transplant donors were typed for HLA class I antigens. HLA DNA typing was performed by polymerase chain reaction/sequence specific primer method for class II. HLA typing for class I was performed by serological method. The frequency of HLA DRB1*03 was 0.6340 in patients compared to 0.2950 in controls (P = 0.0014). The frequency of HLA DRB1*04 was found to be 0.6830 in patients compared to 0.2950 in controls (P = 0.00026). The allele HLA DRB1*07 was present in 0.390 of patients compared to 0.0820 of the controls (P = 0.0004). A preventive antigen for the manifestation of vitiligo has not been identified in this study. Our findings suggest that DRB1*03, DRB1*04 and DRB1*07 alleles are genetic markers for general susceptibility to vitiligo in a Turkish population.     

Thiol/disulphide homeostasis in pregnant women with Familial Mediterranean fever

Objective: To investigate the presence of oxidative stress (OS) in pregnant women with Familial Mediterranean fever (FMF) in the first trimester by evaluating thiol/disulphide homeostasis.

Study design: A total of 31 pregnant women with a diagnosis of FMF, between 11⁰ and 13⁶ weeks of gestation, were compared with 51 healthy pregnant controls at the same gestational weeks. A recently defined method was used to measure plasma native thiol, total thiol and disulphide levels.

Results: There were no differences between groups in terms of maternal age, body mass index and numbers of gravida and parity. Antenatal complications (45.2% vs. 9.8%, P?=?0.001) and primary caesarean section (22.6% vs. 5.9%, P?=?0.037) were higher in the FMF group. Pregnant women with FMF had significantly lower first trimester serum levels of native thiol (297.5?μmol/l (153.2–441.8) vs. 366.1?μmol/l (288.7–432.4), P?=?0.000), total thiol (327.2?μmol/l (171.0–471.0) vs. 389.9?μmol/l (317.1–449.8), P?=?0.000) and higher levels of disulphide (14.2?±?4.5?μmol/l vs. 12.4?±?3.4?μmol/l, P?=?0.045). No differences were found in these parameters among FMF patients with and without antenatal complications.

Conclusions: The main outcome demonstrates a relation between OS and pregnant women with FMF in the first trimester of gestation. OS in the first trimester may be a major aetiological factor of unfavourable pregancy outcomes in this group of patients.     

Purification and characterization of Mycobacterium tuberculosis 1D-myo-inosityl-2-acetamido-2-deoxy-alpha-D-glucopyranoside deacetylase, MshB, a mycothiol biosynthetic enzyme

Mycothiol (MSH, AcCys-GlcN-Ins) is the major low molecular weight thiol in actinomycetes and is essential for growth of Mycobacterium tuberculosis. MshB, the GlcNAc-Ins deacetylase, is a key enzyme in MSH biosynthesis. MshB from M. tuberculosis was cloned, expressed, purified, and its properties characterized. Values of k(cat) and K(m) for MshB were determined for the biological substrate, GlcNAc-Ins, and several other good substrates. The substrate specificity of MshB was compared to that of M. tuberculosis mycothiol S-conjugate amidase (Mca), a homologous enzyme having weak GlcNAc-Ins deacetylase activity. Both enzymes are metalloamidases with overlapping amidase activity toward mycothiol S-conjugates (AcCySR-GlcN-Ins). The Ins residue and hydrophobic R groups enhance the activity with both MshB and Mca, but changes in the acyl group attached to GlcN have opposite effects on the two enzymes.     

The antioxidants alpha-lipoic acid and N-acetylcysteine reverse memory impairment and brain oxidative stress in aged SAMP8 mice

Oxidative stress may play a crucial role in age-related neurodegenerative disorders. Here, we examined the ability of two antioxidants, alpha-lipoic acid (LA) and N-acetylcysteine (NAC), to reverse the cognitive deficits found in the SAMP8 mouse. By 12 months of age, this strain develops elevated levels of Abeta and severe deficits in learning and memory. We found that 12-month-old SAMP8 mice, in comparison with 4-month-old mice, had increased levels of protein carbonyls (an index of protein oxidation), increased TBARS (an index of lipid peroxidation) and a decrease in the weakly immobilized/strongly immobilized (W/S) ratio of the protein-specific spin label MAL-6 (an index of oxidation-induced conformational changes in synaptosomal membrane proteins). Chronic administration of either LA or NAC improved cognition of 12-month-old SAMP8 mice in both the T-maze footshock avoidance paradigm and the lever press appetitive task without inducing non-specific effects on motor activity, motivation to avoid shock, or body weight. These effects probably occurred directly within the brain, as NAC crossed the blood-brain barrier and accumulated in the brain. Furthermore, treatment of 12-month-old SAMP8 mice with LA reversed all three indexes of oxidative stress. These results support the hypothesis that oxidative stress can lead to cognitive dysfunction and provide evidence for a therapeutic role for antioxidants.     

The Protective Effect of N-Acetylcysteine on Oxidative Stress in the Brain Caused by the Long-Term Intake of Aspartame by Rats

Long-term intake of aspartame at the acceptable daily dose causes oxidative stress in rodent brain mainly due to the dysregulation of glutathione (GSH) homeostasis. N-Acetylcysteine provides the cysteine that is required for the production of GSH, being effective in treating disorders associated with oxidative stress. We investigated the effects of N-acetylcysteine treatment (150 mg kg^?1, i.p.) on oxidative stress biomarkers in rat brain after chronic aspartame administration by gavage (40 mg kg^?1). N-Acetylcysteine led to a reduction in the thiobarbituric acid reactive substances, lipid hydroperoxides, and carbonyl protein levels, which were increased due to aspartame administration. N-Acetylcysteine also resulted in an elevation of superoxide dismutase, glutathione peroxidase, glutathione reductase activities, as well as non-protein thiols, and total reactive antioxidant potential levels, which were decreased after aspartame exposure. However, N-acetylcysteine was unable to reduce serum glucose levels, which were increased as a result of aspartame administration. Furthermore, catalase and glutathione S-transferase, whose activities were reduced due to aspartame treatment, remained decreased even after N-acetylcysteine exposure. In conclusion, N-acetylcysteine treatment may exert a protective effect against the oxidative damage in the brain, which was caused by the long-term consumption of the acceptable daily dose of aspartame by rats.     

Nintedanib reduces ventilation‐augmented bleomycin‐induced epithelial–mesenchymal transition and lung fibrosis through suppression of the Src pathway

Mechanical ventilation (MV) used in patients with acute respiratory distress syndrome (ARDS) can increase lung inflammation and pulmonary fibrogenesis. Src is crucial in mediating the transforming growth factor (TGF)‐β1‐induced epithelial–mesenchymal transition (EMT) during the fibroproliferative phase of ARDS. Nintedanib, a multitargeted tyrosine kinase inhibitor that directly blocks Src, has been approved for the treatment of idiopathic pulmonary fibrosis. The mechanisms regulating interactions among MV, EMT and Src remain unclear. In this study, we suggested hypothesized that nintedanib can suppress MV‐augmented bleomycin‐induced EMT and pulmonary fibrosis by inhibiting the Src pathway. Five days after administrating bleomycin to mimic acute lung injury (ALI), C57BL/6 mice, either wild‐type or Src‐deficient were exposed to low tidal volume (V_T) (6 ml/kg) or high V_T (30 ml/kg) MV with room air for 5 hrs. Oral nintedanib was administered once daily in doses of 30, 60 and 100 mg/kg for 5 days before MV. Non‐ventilated mice were used as control groups. Following bleomycin exposure in wild‐type mice, high V_T MV induced substantial increases in microvascular permeability, TGF‐β1, malondialdehyde, Masson's trichrome staining, collagen 1a1 gene expression, EMT (identified by colocalization of increased staining of α‐smooth muscle actin and decreased staining of E‐cadherin) and alveolar epithelial apoptosis (P < 0.05). Oral nintedanib, which simulated genetic downregulation of Src signalling using Src‐deficient mice, dampened the MV‐augmented profibrotic mediators, EMT profile, epithelial apoptotic cell death and pathologic fibrotic scores (P < 0.05). Our data indicate that nintedanib reduces high V_T MV‐augmented EMT and pulmonary fibrosis after bleomycin‐induced ALI, partly by inhibiting the Src pathway.     

Chemopreventive effect of bilberry (Vaccinium myrtillus) against cisplatin-induced oxidative stress and DNA damage as shown by the comet assay in peripheral blood of rats

The aim of this study was to evaluate the chemopreventive effect of bilberry on cisplatin induced oxidative stress and DNA damage in rat blood. Twenty-one female Wistar-Albino rats were divided into three groups: group I — untreated; group II — treated with cisplatin (single dose 7.5 mg/kg b.w.); and group III — treated with cisplatin (single dose 7.5 mg/kg b.w.) and bilberry (200 mg/kg b.w. for 10 days). Antioxidant enzyme systems including superoxide dismutase, catalase, glutathione peroxidase and the level of malondialdehyde (MDA) that might occur on erythrocytes have been determined and single cell gel electrophoresis (comet) was utilized to evaluate the DNA damage in lymphocytes. Treatment with cisplatin has increased the levels of MDA and decreased antioxidant enzymes in erythrocytes. Comet assay showed significantly higher values at dose of 7.5 mg/kg cisplatin as the result of oxidative DNA damage when compared to the control group. Cisplatin treatment with bilberry resulted in a highly significant (P < 0.05) decreased in the lymphocytes DNA when compared to the cisplatin group. Bilberry has been effective on antioxidant enzyme systems and MDA level and significantly decreased the comets. Our results indicate that bilberry is capable of preventing genotoxic and cytotoxic damage caused by cisplatin in peripheral blood cells in rats.     

Sleep measurements in women with dysthymic disorder and insomnia

Sleep and Biological Rhythms - To determine the effects of trazodone, mirtazapine and hydroxyzine on sleep profiles of dysthymic disorder (DD) women with selective serotonin reuptake inhibitor...