Silibinin improves palmitate-induced insulin resistance in C2C12 myotubes by attenuating IRS-1/PI3K/Akt pathway inhibition

The present study investigated the effect of silibinin, the principal potential anti-inflammatory flavonoid contained in silymarin, a mixture of flavonolignans extracted from Silybum marianum seeds, on palmitate-induced insulin resistance in C2C12 myotubes and its potential molecular mechanisms. Silibinin prevented the decrease of insulin-stimulated 2-NBDG (2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose) uptake and the downregulation of glutamate transporter type 4 (GLUT4) translocation in C2C12 myotubes induced by palmitate. Meanwhile, silibinin suppressed the palmitate-induced decrease of insulin-stimulated Akt Ser473 phosphorylation, which was reversed by wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K). We also found that palmitate downregulated insulin-stimulated Tyr632 phosphorylation of insulin receptor substrate 1 (IRS-1) and up-regulated IRS-1 Ser307 phosphorylation. These effects were rebalanced by silibinin. Considering several serine/threonine kinases reported to phosphorylate IRS-1 at Ser307, treatment with silibinin downregulated the phosphorylation of both c-Jun N-terminal kinase (JNK) and nuclear factor-κB kinase β (IKKβ), which was increased by palmitate in C2C12 myotubes mediating inflammatory status, whereas the phosphorylation of PKC-θ was not significantly modulated by silibinin. Collectively, the results indicated that silibinin prevented inhibition of the IRS-1/PI3K/Akt pathway, thus ameliorating palmitate-induced insulin resistance in C2C12 myotubes.

High prevalence of methicillin resistance and PVL genes amongStaphylococcus aureus isolates from the nares and skin lesions of pediatric patients with atopic dermatitis

Staphylococcus aureus is highly prevalent among patients with atopic dermatitis (AD), and this pathogen may trigger and aggravate AD lesions. The aim of this study was to determine the prevalence of S. aureus in the nares of pediatric subjects and verify the phenotypic and molecular characteristics of the isolates in pediatric patients with AD. Isolates were tested for antimicrobial susceptibility, SCCmectyping, and Panton-Valentine Leukocidin (PVL) genes. Lineages were determined by pulsed-field gel electrophoresis and multilocus sequence typing (MLST). AD severity was assessed with the Scoring Atopic Dermatitis (SCORAD) index. Among 106 patients, 90 (85%) presented S. aureus isolates in their nares, and 8 also presented the pathogen in their skin infections. Two patients had two positive lesions, making a total of 10 S. aureusisolates from skin infections. Methicillin-resistant S. aureus(MRSA) was detected in 24 (26.6%) patients, and PVL genes were identified in 21 (23.3%), including 6 (75%) of the 8 patients with skin lesions but mainly in patients with severe and moderate SCORAD values (P=0.0095). All 24 MRSA isolates were susceptible to trimethoprim/sulfamethoxazole, while 8 isolates had a minimum inhibitory concentration (MIC) to mupirocin >1024 μg/mL. High lineage diversity was found among the isolates including USA1100/ST30, USA400/ST1, USA800/ST5, ST83, ST188, ST718, ST1635, and ST2791. There was a high prevalence of MRSA and PVL genes among the isolates recovered in this study. PVL genes were found mostly among patients with severe and moderate SCORAD values. These findings can help clinicians improve the therapies and strategies for the management of pediatric patients with AD.

Late emergence of A594V and L595W mutations related to ganciclovir resistance in a patient with HCMV retinitis and long-term HIV progression

The emergence of ganciclovir (GCV) resistance during the treatment of human cytomegalovirus (HCMV) infection is a serious clinical challenge, and is associated with high morbidity and mortality. In this case report, we describe the emergence of two consecutive mutations (A594V and L595W) related to GCV resistance in a patient with HCMV retinitis and long-term HIV progression after approximately 240 days of GCV use. Following the diagnosis of retinitis, the introduction of GCV did not result in viral load reduction. The detected mutations appeared late in the treatment, and we propose that other factors (high initial HCMV load, previous GCV exposure, low CD4+ cell count), in addition to the presence of resistance mutations, may have contributed to the treatment failure of HCMV infection in this patient.

A single resistance exercise session improves myocardial contractility in spontaneously hypertensive rats

Resistance training evokes myocardial adaptation; however, the effects of a single resistance exercise session on cardiac performance are poorly understood or investigated. This study aimed to investigate the effects of a single resistance exercise session on the myocardial contractility of spontaneously hypertensive rats (SHRs). Male 3-month-old SHRs were divided into two groups: control (Ct) and exercise (Ex). Control animals were submitted to sham exercise. Blood pressure was measured in conscious rats before the exercise session to confirm the presence of arterial hypertension. Ten minutes after the exercise session, the animals were anesthetized and killed, and the hearts were removed. Cardiac contractility was evaluated in the whole heart by the Langendorff technique and by isometric contractions of isolated left ventricular papillary muscles. SERCA2a, phospholamban (PLB), and phosphorylated PLB expression were investigated by Western blot. Exercise increased force development of isolated papillary muscles (Ex=1.0±0.1 g/mg vs Ct=0.63±0.2 g/mg, P<0.05). Post-rest contraction was greater in the exercised animals (Ex=4.1±0.4% vs Ct=1.7±0.2%, P<0.05). Papillary muscles of exercised animals developed greater force under increasing isoproterenol concentrations (P<0.05). In the isolated heart, exercise increased left ventricular isovolumetric systolic pressure (LVISP; Δ +39 mmHg; P<0.05) from baseline conditions. Hearts from the exercised rats presented a greater response to increasing diastolic pressure. Positive inotropic intervention to calcium and isoproterenol resulted in greater LVISP in exercised animals (P<0.05). The results demonstrated that a single resistance exercise session improved myocardial contractility in SHRs.

Overexpression of Salmonella enterica serovar Typhi recA gene confers fluoroquinolone resistance in Escherichia coli DH5α

A spontaneous fluoroquinolone-resistant mutant (STM1) was isolated from its parent Salmonella enterica serovar Typhi (S. Typhi) clinical isolate. Unlike its parent isolate, this mutant has selective resistance to fluoroquinolones without any change in its sensitivity to various other antibiotics. DNA gyrase assays revealed that the fluoroquinolone resistance phenotype of the STM1 mutant did not result from alteration of the fluoroquinolone sensitivity of the DNA gyrase isolated from it. To study the mechanism of fluoroquinolone resistance, a genomic library from the STM1 mutant was constructed in Escherichia coli DH5α and two recombinant plasmids were obtained. Only one of these plasmids (STM1-A) conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. The chromosomal insert from STM1-A, digested with EcoRI and HindIII restriction endonucleases, produced two DNA fragments and these were cloned separately into pUC19 thereby generating two new plasmids, STM1-A1 and STM1-A2. Only STM1-A1 conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. Sequence and subcloning analyses of STM1-A1 showed the presence of an intact RecA open reading frame. Unlike that of the wild-type E. coli DH5α, protein analysis of a crude STM1-A1 extract showed overexpression of a 40 kDa protein. Western blotting confirmed the 40 kDa protein band to be RecA. When a RecA PCR product was cloned into pGEM-T and introduced into E. coli DH5α, the STM1-A11 subclone retained fluoroquinolone resistance. These results suggest that overexpression of RecA causes selective fluoroquinolone resistance in E. coli DH5α.

HLA-DR3 antigen in the resistance to idiopathic dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) has been hypothesized as a multifactorial disorder initiated by an environment trigger in individuals with predisposing human leukocyte antigen (HLA) alleles. Published data on the association between HLA-DR3 antigen and IDC risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Studies were identified by searching the PUBMED and Embase database (starting from June 2015). A total of 19 case-control studies including 1378 cases and 10383 controls provided data on the association between HLA-DR3 antigen and genetic susceptibility to IDC. Overall, significantly decreased frequency of HLA-DR3 allele (OR=0.72; 95%CI=0.58-0.90; P=0.004) was found in patients with IDC compared with controls. When stratified by myocardial biopsy or non-biopsy cases, statistically decreased risk was found for IDC in myocardial biopsy cases (OR=0.69; 95%CI=0.57-0.84; P=0.0003). In the subgroup analysis by ethnicity, borderline statistically significantly decreased risk was found among Europeans from 12 case-control studies (OR=0.76; 95%CI=0.58-1.00; P=0.05). In conclusion, our results suggest that individuals with HLA-DR3 antigen may have a protective effect against IDC.

Erythropoietin resistance in end-stage renal disease patient with gastric antral vascular ectasia

AbstractWe observed a case of recombinant human erythropoietin resistance caused by Gastric Antral Vascular Ectasia in a 40-year-old female with ESRD on hemodialysis. Some associated factors such as autoimmune disease, hemolysis, heart and liver disease were discarded on physical examination and complementary tests. The diagnosis is based on the clinical history and endoscopic appearance of watermelon stomach. The histologic findings are fibromuscular proliferation and capillary ectasia with microvascular thrombosis of the lamina propria. However, these histologic findings are not necessary to confirm the diagnosis. Gastric Antral Vascular Ectasia is a serious condition and should be considered in ESRD patients on hemodialysis with anemia and resistance to recombinant human erythropoietin because GAVE is potentially curable with specific endoscopic treatment method or through surgical procedure.

Erythropoietin resistance in end-stage renal disease patient with gastric antral vascular ectasia

AbstractWe observed a case of recombinant human erythropoietin resistance caused by Gastric Antral Vascular Ectasia in a 40-year-old female with ESRD on hemodialysis. Some associated factors such as autoimmune disease, hemolysis, heart and liver disease were discarded on physical examination and complementary tests. The diagnosis is based on the clinical history and endoscopic appearance of watermelon stomach. The histologic findings are fibromuscular proliferation and capillary ectasia with microvascular thrombosis of the lamina propria. However, these histologic findings are not necessary to confirm the diagnosis. Gastric Antral Vascular Ectasia is a serious condition and should be considered in ESRD patients on hemodialysis with anemia and resistance to recombinant human erythropoietin because GAVE is potentially curable with specific endoscopic treatment method or through surgical procedure.

Does Gamma-aminobutyric acid function as a plant resistance mechanism against phytophagous insect activity? /

Gamma-aminobutyric acid (GAB A) is a ubiquitous non-protein amino acid synthesized via the decarboxylation of L-glutamate in a reaction catalyzed by the cytosolic enzyme L-glutamate decarboxylase (GAD). In animals it functions as an inhibitory neurotransmitter. In plants it accumulates rapidly in response to various stresses, but its function remains unclear. The hypothesis that GABA accumulation in leaf tissue may function as a plant resistance mechanism against phytophagous insect activity was investigated. GABA accumulation in response to mechanical stimulation, mechanical damage and insect activity was demonstrated. In wt tobacco (Nicotiana tabacum cv Samsun), mechanical stimulation or damage caused GABA to accumulate within 2 min from mean levels of 14 to 37 and 1~9 nmol g-l fresh weight (FW), respectively. In the transgenic tobacco strain CaMVGAD27c overexpressing Petunia GAD, the same treatments caused GABA to accumulate from 12 to 59 and 279 nmol g-l FW, respectively. In the transgenic tobacco strain CaMVGADilC 11 overexpressing Petunia GAD lacking an autoinhibitory domain, mechanical stimulation or damage caused GABA to accumulate from 180 to 309 and 630 nmol g-l FW, respectively. Ambulatory activity by tobacco budworm (TBW) larvae (Heliothis virescens) on leaves of CaMVGAD27c tobacco caused GABA to accumulate from 28 to 80 nmol g-l FW within 5 min. Ambulatory and leaf-rolling activity by oblique banded leaf roller (OBLR) larvae (Choristoneura rosaceana cv Harris) on wt soybean leaves (Glycine max cv Harovinton) caused GABA to accumulate from 60 to 1123 nmol g-l FW within 20 min. Increased GABA levels in leaf tissue were shown to affect phytophagous preference in TBW larvae presented with wt and transgenic tobacco leaves. When presented with leaves of Samsun wt and CaMVGAD27c plants, TBW larvae consumed more wt leaf tissue (640 ± 501 S.D. mm2 ) than transgenic leaf tissue (278 ± 338 S.D. mm2 ) nine times out of ten. When presented with leaves of Samsun wt and CaMVGAD~C11 plants, TBW larvae consumed more transgenic leaf tissue (1219 ± 1009 S.D. mm2 ) than wt leaf tissue (28 ± 31 S.D. mm2 ) ten times out of ten. These results indicate that: (1) ambulatory activity of insect larvae on leaves results in increased GABA levels, (2) transgenic tobacco leaves with increased capacity for GABA synthesis deter feeding, and (3) transgenic tobacco leaves with constitutively higher GABA levels stimulate feeding.

Incidence of resistance to benzimidazole fungicides in a field population of Venturia inaequalis /

The allele-specific polymerase chain reaction (PCR) was used to screen for the presence of benomyl resistance, and to characterize their levels and frequencies in field populations of Venturia inaequalis during two seasons. Three hundred isolates of V. inaequalis were collected each season from infected leaves of MalusX domestica. Borkh c.v. Mcintosh. The trees used were sprayed in the year prior to collection with five applications of benomyl, its homologue Azindoyle, or water. Monoconidial isolates of V. inaequalis were grown on 2% potato dextrose agar (PDA) for four weeks. Each isolate was taken from a single lesion from a single leaf. Total genomic DNA was extracted from the four week old colonies of V. inaequalis, prepared and used as a template in PCR reactions. PCR reactions were achieved by utilizing allele-specific primers. Each primer was designed to amplify fragments from a specific allele. Primer Vin was specific for mutations conferring the ben^^"^ phenotype. It was expected to amplify a 171 bp. DNA fragment from the ben^"^ alleles only. Primers BenHR and BenMR were specific for mutations conferring the ben"" and ben'^'' phenotypes, respectively. They were expected to amplify 172 bp. and 165 bp. DNA fragments from the ben"" and ben"^" alleles, respectively. Of the 953 isolates tested, 414 (69.9%) were benomyl sensitive (ben^) and 179 (30.1%) were benomyl resistant. All the benomyl resistant alleles were ben^"", since neither the ben"" nor the ben"" alleles were detected. Frequencies of benomyl resistance were 23%, 24%, and 23% for the 1997 collections, and were 46%, 26% and 38% for the 1998 collections for benomyl, Azindoyle and water treatments, respectively. Growth assay was performed to evaluate the applicability of using PCR in monitoring benomyl resistance in fungal field populations. Tests were performed on 14 isolates representing the two phenotypes (ben^ and ben^"'' alleles) characterized by PCR. Results of those tests were in agreement with PCR results. Enzyme digestion was also used to evaluate the accuracy and reliability of PCR products. The mutation associated with the ben^"'' phenotype creates a unique site for the endonuclease enzyme Bsh^236^ allowing the use of enzyme digestion. Isolates characterized by PCR as ben^'^'^ alleles had this restriction site for the SsA7l2361 enzyme. The most time consuming aspect of this study was growing fungal isolates on culture media for DNA extraction. In addition, the risk of contamination or losing the fungus during growth processes was relatively high. A technique for extracting DNA directly from lesions on leaves has been used (Luck and Gillings 1 995). In order to apply this technique in experiments designed to monitor fungicide resistance, a lesion has to be homogeneous for fungicide sensitivity. For this purpose, PCR protocol was used to determine lesion homogeneity. One hundred monoconidial isolates of V. inaequalis from 10 lesions (10-conidia/ lesion) were tested for their phenotypes with respect to benomyl sensitivity. Conidia of six lesions were homogeneous, while conidia of the remaining lesions were mixtures of ben^ and ben^ phenotypes. Neither the ben" nor the ben' phenotype was detected.

The genetics of glucosamine resistance in yeast /

Thesis (M. Sc.) - Brock University, 1975.

Education in the halls : students' perspectives on cultural expression and resistance

This research is a qualitative study of cultural reproduction and resistance from students' perspectives. Thirteen teenagers (eight in attendance in regular high schools and five drop-outs) were recruited to take part and were involved to varying degrees through interviews, journal writing, and group interactive sessions. A purposive sampling design was used initially to recruit individuals known to the researcher through contacts in an alternate education setting. Other participants were recruited throughout the research phase. The theoretical aspects are premised on the work of Paul Willis, Michel Foucault, and Pierre Bourdieu. The reflexive praxeology of Bourdieu reflects the position taken as one way of understanding how students construct and respond to the situations of cultural dominance they experience in schools. The same reflexivity is offered for suggestions as to how teachers can respond to their own position in the education system.

Glucosamine resistance in the yeast, Saccharomyces cerivisae [sic]

By using glucosamine resistant mutants of Saccharomyces ceriv~sa~ an attempt was made to discover the mechanisms which cause glucose repression and/or the Crabtree effect. The strains used are 4B2, GR6, lOP3r, GR8l and GRI08. 4B2 is a wild type yeast while the others are its mutants. To characterize the biochemical reactions which made these mutants resistant to glucosamine poisoning the following experiments were done~ 1. growth and respiration; 2. transport of sugars; 3. effect of inorganic phosphate (Pi): 4. Hexokinase; 5. In yivo phosphorylation. From the above experiments the following conclusions may be drawn: (i) GR6 and lOP3r have normal respiratory and fermentative pathways. These mutants are resistant to glucosamine poisoning due to a slow rate of sugar transport which is due to change in the cell membrane. (ii) GR8l has a normal respiratory pathway. The slow growth on fermentable carbon sourCEE indicates that in GR8l the lesion is in or associated with the glycolytic pathway. The lower rate of sugar transport may be due to a change in energy metabolism. The invivo phosphorylation rate indicates that in GR81 facilitated diffusion is the dominant transport mechanism. (iii) GR108 msa normal glycolytic pathway but the respiratory pathway is abnormal. The slow rate of sugar transport is due to a change in energy metabolism. The lower percentage of in vivo phosphorylation is probably due to a lowered availability of ATP because of the mitochondrial lesion. In all mutants resistance to glucosamine poisoning is due to a lower rate of utilization of ATP. which is caused by various mechanisms (see above), making less ADP available for phosphorylation via ATP synthase which utilizes inorganic phosphate. Because of the lower utilization of Pi, the concentration of intra-mitochondrial Pi does not go down thus protecting mutants from glucosamine poisoning.

The genetics of glucosamine in yeast : cytoplasmic determinants conferring resistance

Two cytoplasmic, glucosamine resistant mutants of Saccharomyces cerevisiae, GR6 and GR10, were examined to determine whether or not the lesions involved were located on mitochondrial DNA. Detailed investigation of crosses of GR6 and GR10 or their derivatives to strains bearing known mitochondrial markers demonstrated that: 1. the frequency of glucos~~ine resistance in diploids was independent of factors influencing mitochondrial marker output. 2. upon tetrad analysis a variety of tetrad ratios was observed for glucosamine resistance whereas mitochondrial markers segregated 4:0 or 0:4 (resistant:sensitive). 3. glucosamine resistance and mitochondrial markers segregated differentially with time. 4. glucosamine resistance persisted following treatment of a GRIO derivative with ethidium bromide at concentrations high enough to eliminate all mitochondrial DNA. 5. haploid spore clones displayed two degrees of glucosamine resistance, weak and strong, while growth due to mitochondrial mutations was generally thick and confluent. 6. a number of glucosamine resistant diploids and haploids, which also possessed a mithchondrial resistance mutation, were unable to grow on medium containing both glucosamine and the particular drug involved. 3 These observations 1~ 6 provided strong evidence that the cytoplasmic glucosamine resistant mutations present in GR6 and GRiO were not situated on mitochondrial DNA. Comparison of the glucosamine resistance mutations to some other known cytoplasmic determinants revealed that: 7. glucosamine resistance and the expression of the killer phenotype were separate phenomena. 8. unlike yeast carrying resistance conferring episomes GR6 and GR10 were not resistant to venturicidin or oligomycin and the GR factor exhibited genetic behaviour different from that of the episomal determinants. These results 7--+8 suggested that glucosamine resistance was not associated with the killer determinant nor with alleged yeast episomes. It is therefore proposed that a yeast plasmid(s), previously undescribed, is responsible for glucosamine resistance. The evidence to date is compatible with the hypothesis that GR6 and GR10 carry allelic mutations of the same plasmid which is tentatively designated (GGM).