Molecular characterization of toxigenic and atoxigenic Aspergillus flavus isolates, collected from peanut fields in China

AIMS

The objectives of this study were to assess the genetic relationships between toxigenic and atoxigenic isolates of Aspergillus flavus collected from peanut fields in China, and to analyse deletions within the aflatoxin biosynthetic gene cluster for the atoxigenic isolates.

METHODS AND RESULTS

Analysis of random-amplified polymorphic DNA and microsatellite-primed PCR data showed that the toxigenic and atoxigenic isolates of A. flavus were not clustered based on their regions and their ability of aflatoxin and sclerotial production. These results were further supported by DNA sequence of ITS, pksA and omtA genes. PCR assays showed that 24 of 35 isolates containing no detectable aflatoxins had the entire aflatoxin gene cluster. Eleven atoxigenic isolates had five different deletion patterns in the cluster.

CONCLUSIONS

Toxigenic and atoxigenic isolates of A. flavus are genetically similar, but some atoxigenic isolates having deletions within the aflatoxin gene cluster can be identified readily by PCR assays.

SIGNIFICANCE AND IMPACT OF THE STUDY

Because the extensive deletions within the aflatoxin gene cluster are not rare in the atoxigenic isolates, analysis of deletion within the cluster would be an effective method for the rapid screening of atoxigenic isolates for developing biocontrol agents.

Plasminogen activator inhibitor-1 and asthma: role in the pathogenesis and molecular regulation

Plasminogen activator inhibitor (PAI)-1 is a major inhibitor of the fibrinolytic system. PAI-1 levels are markedly increased in asthmatic airways, and mast cells (MCs), a pivotal cell type in the pathogenesis of asthma, are one of the main sources of PAI-1 production. Recent studies suggest that PAI-1 may promote the development of asthma by regulating airway remodelling, airway hyperresponsiveness (AHR), and allergic inflammation. The single guanosine nucleotide deletion/insertion polymorphism (4G/5G) at -675 bp of the PAI-1 gene is the major genetic determinant of PAI-1 expression. Plasma PAI-1 level is higher in people with the 4G/4G genotype than in those with the 5G/5G genotype. A strong association between the 4G/5G polymorphism and the risk and the severity of asthma has been suggested. Levels of plasma IgE and PAI-1 and severity of AHR are greater in asthmatic patients with the 4G/4G genotype than in those with the 5G/5G genotype. The PAI-1 promoter with the 4G allele renders higher transcription activity than the PAI-1 promoter with the 5G allele in stimulated MCs. The molecular mechanism for the 4G allele-mediated higher PAI-1 expression is associated with greater binding of upstream stimulatory factor-1 to the E-box adjacent to the 4G site (E-4G) than to the E-5G. In summary, PAI-1 may play an important role in the pathogenesis of asthma. Further studies evaluating the mechanisms of PAI-1 action and regulation may lead to the development of a novel prognostic factor and therapeutic target for the treatment and prevention of asthma and other PAI-1-associated diseases.

Characterization of sterol demethylation inhibitor-resistant isolates of Fusarium asiaticum and F. graminearum collected from wheat in China

Fusarium asiaticum and F. graminearum are the primary causal agents of Fusarium head blight (FHB) of wheat in China. In this study, sensitivities of 159 F. asiaticum and F. graminearum isolates to a benzimidazole fungicide carbendazim (MBC) and to sterol demethylation inhibitors (DMIs) tebuconazole and prochloraz were determined. Among the 159 isolates, 9 were resistant to MBC and designated as MBC-R isolates. Three showed resistance to tebuconazole and prochloraz and designated as DMI-R isolates. There was no cross-resistance between MBC and DMI. Genetic analysis by microsatellite-primed polymerase chain reaction (PCR) showed that MBC-R or DMI-R isolates had different genotypes, which indicated that they originated from different wild-type parents. Analysis of two 14alpha-demethylase (cyp51) homologous genes (cyp51A and cyp51B) showed that the F. asiaticum isolates could be distinguished from F. graminearum isolates based on the sequence of cyp51A. Analysis of deduced amino acid sequence of cyp51A and cyp51B suggested that no mutations were associated with DMI resistance. Real-time PCR analysis showed that the DMI resistance was not related to the expression of cyp51A and cyp51B in F. asiaticum and F. graminearum, but expressions of both genes were induced greatly by the tebuconazole. Results of this study indicated that cyp51A would be an informative marker for analysis of population structure of F. asiaticum and F. graminearum, and the existence of homologous cyp51 genes in F. asiaticum and F. graminearum could provide new insights into DMI resistance in phytopathogenic fungi.

Simultaneous detection of Fusarium asiaticum and Fusarium graminearum in wheat seeds using a real-time PCR method

AIMS

To develop a PCR-based method for quantitative detection of Fusarium asiaticum (Fa) and Fusarium graminearum (Fg) in wheat seeds.

METHODS AND RESULTS

Based on the sequences of the cyp51A gene, two primer pairs FaF + FaR and FgF + FgR were developed for the species-specific detection of Fa and Fg, respectively. To simultaneously detect these two phylogenetic species, a pair of primers FgaF + FgaR was developed based on the first and the second introns of beta-tubulin gene. This primer pair amplified a 228-bp fragment only from Fa and Fg isolates, but not from 22 other Fusarium spp. and 13 other fungal species. A real-time PCR with this primer pair was able to quantify minute amounts of Fa and Fg DNA in wheat seeds rapidly.

CONCLUSIONS

PCR primers designed based on the sequence of cyp51A or intron region of beta-tubulin gene could allow differentiation of genetically related fungal species.

SIGNIFICANCE AND IMPACT OF THE STUDY

The sensitive and quantitative detection method can be readily used in epidemiological studies and in assessing risk of Fusarium mycotoxin contamination in wheat samples.

Management of delayed intrathoracic esophageal perforation with modified intraluminal esophageal stent

In this article, we reviewed our experience of treatment of the delayed intrathoracic nonmalignant esophageal perforation employing modified intraluminal esophageal stent. Between February 1990 and August 2006, eight patients were included in this study. Five patients experienced sepsis. The interval time between perforation and stent placement ranged from 36 h to 27 days (average, 8.6 days). Esophageal stenting and throracotomy for foreign body removal were performed in four patients. The remaining four patients underwent stent placement and thoracostomy. Nutrition was initiated through gastrostomy after 7 to 10 days after the stenting. The stent was removed after the patients resumed oral intake of food and the esophagogram showed that perforation was closed. There was no death in this group. Signs of sepsis remitted 1 week after stent placement. Complications included stress ulcer, stimulative cough, and pneumonia each. Stent removal ranged 32 to 120 days (average 66.7) after its placement. The stent was kept in place for 4 months to prevent formation of esophageal stricture in one patient with caustic esophageal burns. The follow-up was completed in all the patients. The mean follow-up period was 59 months (range 12-180). One patient with caustic esophageal burn underwent cicatricial esophagectomy and gastric transposition 3 years later due to the esophageal stricture. Barium swallow demonstrated that there was a diverticulum-like outpouching in one patient and slight esophageal stricture at T2 and T3 level in another. One patient developed reflux esophagitis 5 years after stent removal. All the patients finally had a normal intake of food. Modified esophageal stenting is an effective method to manage the delayed intrathoracic esophageal perforation. Prevention of stent migration and its convenient adjustment might be the major advantages of this method.

Immunization against inhibin enhances both embryo quantity and quality in Holstein heifers after superovulation and insemination with sex-sorted semen

The objective was to investigate the feasibility of improving embryo yield in superovulated cows following insemination with sex-sorted semen by prior immunization against inhibin. Twenty-eight heifers were allocated into three groups: High (n=10), Low (n=10), and Control (n=8). The High group received one primary (1mg) and two booster (0.5mg) vaccinations (28-d intervals) with a recombinant inhibin alpha-subunit in 1 mL of white oil adjuvant, whereas the Low group received half that dose, and the Control group received only adjuvant. After the last immunization, all heifers underwent a standard superovulation treatment (decreasing doses of pFSH for 4d), followed by two AI with 2 x 10(6) sex-sorted semen after the onset of estrus. Inhibin-immunized heifers had higher (P<0.01) plasma antibody titres, and an earlier onset of estrus (P<0.05) than Control heifers. The total number of embryo/ova, transferable, and grade 1 embryos in the High group (15.4+/-1.9, 5.7+/-0.7, and 3.8+/-1.0, respectively) was significantly greater than that of the Control group (9.1+/-1.2, 3.1+/-0.5, and 0.6+/-0.2), but was intermediate (P>0.05) in the Low group (13.0+/-2.3, 4.4+/-0.7, and 1.2+/-0.3). There were no significant differences among groups in number of unfertilized ova and degenerated embryos. The High group also had higher (P>0.05) plasma progesterone concentrations on the day of embryo collection. In conclusion, immunization against inhibin improved both embryo quantity and quality following superovulation and insemination with sex-sorted semen.

Caffeic acid phenethyl ester prevents cerebellar granule neurons (CGNs) against glutamate-induced neurotoxicity

Caffeic acid phenethyl ester (CAPE) is an active component of propolis obtained from honeybee hives and is found to have the following properties: anti-mitogenic, anti-carcinogenic, anti-inflammatory, immunomodulatory, and antioxidant. Recent reports suggest that CAPE also has a neuronal protective property against ischemic injury. Since excitotoxicity may play an important role in ischemia, in this study, we investigated whether CAPE could directly protect neurons against excitotoxic insult. We treated cultured rat cerebellar granule neurons (CGNs) with excitotoxic concentrations of glutamate in the presence or absence of CAPE and found that CAPE markedly protected neurons against glutamate-induced neuronal death in a concentration-dependent fashion. Glutamate-induced CGNs death is associated with time-dependent activation of caspase-3 and phosphorylation of p38, both events of which can be blocked by CAPE. Treating CGNs with specific inhibitors of these two enzymes together exerts a synergistic neuroprotective effect, similar to the neuroprotective effect of CAPE exposure. These results suggest that CAPE is able to block glutamate-induced excitotoxicity by inhibiting phosphorylation of p38 and caspase-3 activation. This finding may further help understanding of the mechanism of glutamate-induced neuronal death and CAPE-induced neuroprotection against excitotoxicity.

Development of a real-time PCR assay for the detection of Cladosporium fulvum in tomato leaves

AIMS

The aim of this study was to develop a sensitive real-time polymerase chain reaction (PCR) assay for the rapid detection of Cladosporium fulvum in tomato leaves.

METHODS AND RESULTS

Three PCR primer pairs were designed based on the nucleotide sequences of: (i) the internal transcribed spacer regions of ribosomal RNA; (ii) a microsatellite region amplified by the microsatellite primer M13; and (iii) the beta-tubulin gene of C. fulvum. Each primer pair amplified the expected target DNA fragment from geographically diverse isolates of C. fulvum. No PCR products were amplified with these primer pairs from DNA of other fungal species. Among the three pairs of primers, the primer pair CfF1/CfR1 developed based on the microsatellite region was the most sensitive. Using this sensitive primer pair, a real-time PCR assay was developed to detect early infection of C. fulvum in tomato leaves.

SIGNIFICANCE AND IMPACT OF THE STUDY

DNA regions amplified by the microsatellite primer M13 have a high potential for developing highly sensitive species-specific PCR primers for the detection of phytopathogenic fungi. The real-time PCR assay developed in this study is useful in monitoring early infection of C. fulvum, and can help growers make timely decisions on fungicide application.

Huperzine A regulates amyloid precursor protein processing via protein kinase C and mitogen-activated protein kinase pathways in neuroblastoma SK-N-SH cells over-expressing wild type human amyloid precursor protein 695

Alpha-secretase (alpha-secretase), cleaves the amyloid precursor protein (APP) within the amyloid-beta (Abeta) sequence, resulting in the release of a secreted fragment of APP (alphaAPPs) and precluding Abeta generation. We investigated the effects of the acetylcholinesterase inhibitor, huperzine A (Hup A), on APP processing and Abeta generation in human neuroblastoma SK-N-SH cells overexpressing wild-type human APP695. Hup A dose-dependently (0-10 microM) increased alphaAPPs release. Therefore, we evaluated two alpha-secretase candidates, a disintegrin and metalloprotease (ADAM) 10 and ADAM17 in Hup A-induced non-amyloidogenic APP metabolism. Hup A enhanced the level of ADAM10, and the inhibitor of tumor necrosis factor-alpha converting enzyme (TACE)/ADAM17 inhibited the Hup A-induced rise in alphaAPPs levels, further suggesting Hup A directed APP metabolism toward the non-amyloidogenic alpha-secretase pathway. Hup A had no effect on Abeta generation in this cell line. The steady-state levels of full-length APP and cell viability were unaffected by Hup A. Alpha-APPs release induced by Hup A treatment was significantly reduced by muscarinic acetylcholine receptor antagonists (particularly by an M1 antagonist), protein kinase C (PKC) inhibitors, GF109203X and calphostin C, and the mitogen-activated kinase kinase (MEK) inhibitors, U0126 and PD98059. Furthermore, Hup A markedly increased the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase, which was blocked by treatment with U0126 and PD98059. In addition, Hup A inhibited acetylcholinesterase activity by 20% in neuroblastoma cells. Our results indicate that the activation of muscarinic acetylcholine receptors, PKC and MAP kinase may be involved in Hup A-induced alphaAPPs secretion in neuroblastoma cells and suggest multiple pharmacological mechanisms of Hup A regarding the treatment of Alzheimer's disease (AD).

The effects of interleukin-18 on rat articular chondrocytes: a study of mRNA expression and protein synthesis of proinflammatory substances

Interleukin (IL)-18 is a potent stimulator of immunity and augments the severity of type II collagen-induced arthritis (CIA) in rats and mice by enhancing T helper 1 (Th1) cell activation, which increases the production of proinflammatory cytokines and arthritogenic antibodies. In this study, we show that recombinant IL-18 (rIL-18) also has a direct effect on normal rat chondrocytes maintained in vitro inducing them to produce proinflammatory factors including IL-6, regulated upon activation normal T cell expressed and secreted (RANTES), prostaglandin E(2) (PGE(2)) and prostaglandin F(2alpha) (PGF(2alpha)) in a dose- and time-dependent manner. The production of matrix metalloproteinase (MMP)-13, nitric oxide (NO), tumour necrosis factor (TNF)-alpha and IL-1beta were also enhanced, although less intensely. Neutralizing polyclonal anti-rIL-18 antibodies effectively blocked the production of IL-6, PGE(2) and RANTES, as well as mRNA expression for the same products in addition to IL-18 and TNF-alpha. In contrast, neutralizing antibodies to IL-1beta, TNF-alpha and IL-6 were ineffective in suppressing any of these products. Together, these findings suggest that IL-18 may play an important, possibly direct, role in mediating cartilage injury, which might not be amenable to treatment with currently utilized anti-cytokine agents. These findings suggest further that IL-18 antagonists might prove beneficial as anti-inflammatory and chondroprotective agents in the treatment of arthritis, and that the development of such agents for human use is worth consideration.

Isosteviol reduces plasma glucose levels in the intravenous glucose tolerance test in Zucker diabetic fatty rats

AIM

The aim of this study was to test the effect of isosteviol on blood glucose and insulin levels during the intravenous glucose tolerance test (IVGTT) in Wistar and Zucker diabetic fatty (ZDF) rats.

METHODS

ZDF rats were divided into a control and three isosteviol treatment (1, 5 and 10 mg/kg) groups. Wistar rats were divided into a control group and an isosteviol treatment group (10 mg/kg). The rats were fasted for 12 h prior to infusion of isosteviol and glucose (1.0 g/kg). Blood samples were taken at 0, 5, 15, 30, 60, 90 and 120 min after the injection of glucose. Glucose concentrations were determined by the glucose oxidase method, and plasma insulin was analysed by radioimmunoassay. The area under the curve (AUC) of the net change in plasma glucose concentration was used to compare the isosteviol treatment and control groups.

RESULTS

In ZDF rats, isosteviol at 5 and 10 mg/kg caused a significant (p < 0.05) reduction in the AUC of glucose during the IVGTT. However, isosteviol did not increase plasma insulin concentrations in ZDF rats. In Wistar rats, isosteviol did not significantly affect plasma glucose or insulin levels during the IVGTT.

CONCLUSION

Isosteviol exerts an antihyperglycaemic effect during IVGTT in ZDF rats but not in Wistar rats. Isosteviol has no significant effect on plasma insulin concentrations. The glucose-lowering effect of isosteviol may be due to changes in the sensitivity of peripheral tissues to insulin.

Nociceptin/orphanin FQ decreases serotonin efflux in the rat brain but in contrast to a kappa-opioid has no antagonistic effect on mu-opioid-induced increases in serotonin efflux

Similar to kappa-opioids, nociceptin/orphanin FQ (OFQ) exerts anti-mu-opioid actions. This may involve interactions within the circuitry controlling 5-HT neurons in the dorsal raphe nucleus (DRN) that project to the nucleus accumbens (NAcc). To test this hypothesis, we compared the effects of OFQ and kappa-opioids on 5-HT efflux in the CNS of freely behaving rats. First, OFQ (30-300 microM) infused into the DRN for 120 min dose-dependently decreased 5-HT efflux in the DRN. The opioid receptor-like 1 (ORL-1) antagonist [Nphe(1)]nociceptin(1-13)NH(2) blocked this effect. Using dual-probe microdialysis we observed that OFQ (300 microM) infused into the DRN for 120 min produced parallel decreases in 5-HT efflux in the DRN and NAcc, suggesting that ORL-1 receptors in the DRN inhibit serotonergic neurons projecting to the NAcc. Also, 5-HT efflux in the NAcc was dose-dependently decreased during OFQ (30-300 microM) infusion into the NAcc. This suggests that OFQ can reduce 5-HT efflux in the NAcc both by inhibiting serotonergic neurons in the DRN and by stimulating ORL-1 receptors in the NAcc. Similar to OFQ, the kappa-opioids U-50,488 (300 microM) and dynorphin A(1-13) (300 microM) infused into the DRN for 120 min decreased 5-HT efflux in the DRN. This effect was blocked only by the kappa-opioid receptor antagonist nor-BNI. Lastly, we compared the ability of OFQ and U-50,488 to block mu-opioid-induced increases in 5-HT. The kappa-opioid U-50,488 (1000 microM) attenuated the increase in 5-HT induced by the mu-opioid agonist endomorphin-1 (300 microM) in the DRN. In contrast, OFQ (300-1000 microM) did not alter mu-opioid-induced increases in 5-HT efflux. In summary, kappa-opioids and OFQ both decreased 5-HT efflux in the CNS. However, in contrast to kappa-opioids, which reversed mu-opioid-induced increases in 5-HT efflux, the anti-mu-opioid effects of OFQ apparently do not involve changes in 5-HT transmission under our experimental conditions.

Response to pioglitazone treatment is associated with the lipoprotein lipase S447X variant in subjects with type 2 diabetes mellitus

To investigate the influence of the S447X variant in lipoprotein lipase (LPL) gene on the response rate to therapy with the thiazolidinedione pioglitazone. A total of 113 diabetic patients were treated with pioglitazone 30 mg for 10 weeks. Response to the pioglitazone treatment was defined by either a >10% relative reduction in fasting blood glucose (FBG) or a more than 1% decrease in glycosylated haemoglobin (HbA1c) values after 10 weeks of pioglitazone treatment. The genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism method. Using the criteria >10% relative reduction in FBG after 10 weeks of pioglitaone treatment, responder frequency to pioglitazone treatment in S447S genotype group is significantly higher than S447X genotype group. Meanwhile, the S447X genotype conferred a statistically significant 0.538-fold reduction in response rate to pioglitazone treatment relative to the S447S genotype. Moreover, pioglitazone treatment has significantly beneficial effects on serum lipid profile and blood pressure in S447S genotype carriers. The S447X variant in LPL gene may be a cause for therapy modification by pioglitazone.

[Simulation on the process of female osteoporosis and its prevention by physical activity]

Abstract The processs of female Osteoporosis and its prevention by Physical activity were simulated using anisotropic bone remodelling model with mechanostat combining with finite element method. The results show that bone mass declines slowly at the beginning, bone loss accelerates in postmenopause and bone mass declines 25. 84%-28.63% at the age of 60 and 38.50%-40.44% at the age of 80. Bone mass increases 3.05%-10.26% by an increase of 10%-20% in physical activity. The above results are consistent with clinical observations,which proves that declination of mechanical usage is the primary factor leading to osteoporosis, menopause quickens the process of female osteoporosis, physical activity can decelerate it.

Nutritional implications of patient–provider interactions in hospital settings: evidence from a within-subject assessment of mealtime exchanges and food intake in elderly patients

OBJECTIVE

To examine the nutritional implications of the interactions taking place between patients and care providers during mealtimes in hospital settings. Specifically, we tested research propositions that the amount and nature of interpersonal behaviours exchanged between patients and providers impact patients' food intake. These propositions were derived from prior evidence of social influences on eating behaviour and a well-established framework that identifies two fundamental modalities of human interaction: striving for mastery and power (agency) and efforts to promote union with others (communion).

DESIGN

In a within-subject naturalistic study, participants were observed on multiple meals (n=1477, 46.2 meals/participant on average), during which participants' and providers' agency- and communion-related behaviours and patients' protein and energy intake were recorded. Meal-level frequency and complementarity of patients' and providers' behaviours were computed to test research propositions.

SETTING

Dining room of a geriatric rehabilitation unit.

SUBJECTS

Thirty-two elderly patients (21 females, mean age:78.8, 95% CI: 76.4, 81.1).

RESULTS

Meal-level frequency of patient-provider exchanges (P=0.016) and patients' agency-related behaviours (P=0.029), as well as mutual reciprocation of patients' and providers' communion-related behaviours (P=0.015) on a given meal were positively linked to protein intake. Higher energy intake was found during meals where patients expressed more agency-related behaviours (P=0.029).

CONCLUSION

Results present evidence that the amount and nature of patient-provider interpersonal exchanges on a given meal influence the nutritional quality of food intake in hospitalized elderly. They provide insights into how to improve the design and delivery of routine care to this malnutrition-prone population.

SPONSORSHIP

This study was supported by the Canadian Institutes of Health Research (Operating grant to Laurette Dubé, Doctoral Fellowship to Catherine Paquet) the Fonds de la Recherche en santé du Québec and by the Danone Institute (Doctoral fellowship to Danielle St-Arnaud McKenzie).

Management of achalasia with transabdominal esophagocardiomyotomy and partial posterior fundoplication

In this article we present our experience in the management of achalasia. From May 1988 through August 2005, 71 patients with achalasia underwent transabdominal esophagocardiomyotomy and partial posterior fundoplication. Barium swallow, manometry, and 24-h pH studies were performed in all patients preoperatively. Manometry and 24-h pH monitoring were only carried out in 58 patients at the third post-operative week and in 43 patients during follow-up, even though 52 patients were included in the follow-up. There were no operative deaths or complications. All the 71 patients were able to eat semifluid or solid food without dysphagia and heartburn at discharge. Esophageal barium studies showed that the maximum esophageal diameter decreased 2.2 cm and the minimum gastroesophageal junction diameter increased 8.4 mm after operation. Manometry examination in 58 patients revealed that the lower esophageal sphincter resting pressure decreased 15.0 mmHg in the wake of the procedure. Twenty-four hour pH monitoring demonstrated that reflux events were within the normal post-operative range. Fifty-five of the 58 patients had normal DeMeester scores. Among the patients with a mean 90-month follow-up, 49 patients had normal intake of food without reflux, the remaining three had mild dysphagia without requiring treatment. All the patients resumed their preoperative work and social activities. The manometry and 24-h pH studies in the 43 patients showed there were no significant changes between the third post-operative week and during follow-up. Transabdominal esophagocardiomyotomy and posterior partial fundoplication are able to relieve the functional outflow obstruction of the lower esophageal sphincter, obviate the rehealing of the myotomy edge and prevent gastroesophageal reflux in patients who have undergone myotomy alone.