Prevalence of Salmonella spp. in oysters in the United States

Food-borne diseases such as salmonellosis can be attributed, in part, to the consumption of raw oysters. To determine the prevalence of Salmonella spp. in oysters, oysters harvested from 36 U.S. bays (12 each from the West, East, and Gulf coasts in the summer of 2002, and 12 bays, four per coast, in the winter of 2002-2003) were tested. Salmonella was isolated from oysters from each coast of the United States, and 7.4% of all oysters tested contained Salmonella. Isolation tended to be bay specific, with some bays having a high prevalence of Salmonella, while other bays had none. Differences in the percentage of oysters from which Salmonella was isolated were observed between the summer and winter months, with winter numbers much lower probably due to a variety of weather-related events. The vast majority (78/101) of Salmonella isolates from oysters were Salmonella enterica serovar Newport, a major human pathogen, confirming the human health hazard of raw oyster consumption. Contrary to previous findings, no relationship was found between the isolation of fecal coliforms and Salmonella from oysters, indicating a necessity for specific monitoring for Salmonella and other pathogens rather than the current reliance on fecal coliform testing.     

Identification and synthesis of novel alkaloids from the root system of Nicotiana tabacum: affinity for neuronal nicotinic acetylcholine receptors

A novel pyridine derivative, 3,5-bis-(1-methyl-pyrrolidin-2-yl)-pyridine, and a pair of diastereomers of 1,1'-dimethyl-[2,3']bipyrrolidinyl were isolated from the root of Nicotiana tabacum plants and identified as novel alkaloids by GC-MS analysis. The structures of these new alkaloids were confirmed by total synthesis. The affinities of these novel alkaloids, and other structurally related compounds for alpha4beta2*, alpha7* neuronal nicotinic acetylcholine receptors (nAChRs), and for nAChRs mediating nicotine-evoked dopamine release from rat striatum were also assessed. The results indicate that these compounds do not interact with alpha7* nAChRs, but inhibit [3H]nicotine binding to the alpha4beta2* nAChR subtype. The results also demonstrate that these compounds act as antagonists at nAChRs mediating nicotine-evoked dopamine release from rat striatum.     

Do inhalation general anesthetic drugs induce the neuronal release of endogenous opioid peptides?

The antagonism of some effects of inhalation general anesthetic agents by naloxone suggests that there may be an opioid component to anesthetic action. There is evidence that this opioid action component is due to neuronal release of endogenous opioid peptides. The strongest evidence is provided by studies that monitor changes in the concentration of opioid peptides in the perfused brain following inhalation of the anesthetic. Indirect or circumstantial evidence also comes from studies of anesthetic effects on regional brain levels of opioid peptides, antagonism of selected anesthetic effects by antisera to opioid peptides and anesthetic-induced changes radioligand binding to opioid receptors. It is likely that some inhalation general anesthetics (e.g., nitrous oxide) can induce neuronal release of opioid peptides and that this may contribute to certain components of general anesthesia (e.g., analgesia). More definitive studies utilizing in vivo microdialysis or autoradiography in selected areas of the brain during induction and successive states of general anesthesia have yet to be conducted.     

The Vh8 locus of a new gene-for-gene interaction between Venturia inaequalis and the wild apple Malus sieversii is closely linked to the Vh2 locus in Malus pumila R12740-7A

The wild apple (Malus sieversii) is a large-fruited species from Central Asia, which is used as a source of scab resistance in cultivar breeding. Phytopathological tests with races of Venturia inaequalis were performed to differentiate scab-resistance genes in Malus as well as an avirulence gene in the pathogen. A novel gene-for-gene interaction between V. inaequalis and Malus was identified. The locus of the scab-resistance gene Vh8 is linked with, or possibly allelic to, that of the Vh2 gene in Malus pumila Russian apple R12740-7A, at the lower end of linkage group 2 of Malus. Race 8 isolate NZ188B.2 is compatible with Vh8, suggesting the loss or modification of the complementary AvrVh8 gene, while isolate 1639 overcomes both Vh2 and Vh8, but is incompatible with at least one other gene not detected by any of the other race isolates tested. Our research is the first to differentiate scab-resistance genes in a putative gene cluster in apple with the aid of races of V. inaequalis.     

Phylogenetic congruence of <Emphasis Type="Italic">Sarcocystis neurona</Emphasis> Dubey et al., 1991 (Apicomplexa: Sarcocystidae) in the United States based on sequence analysis and restriction fragment length polymorphism (RFLP)

The objectives of the present study were to assess the genetic diversity, phylogeny and phylogeographical relationships of available Sarcocystis neurona isolates from different localities in the United States. All 13 Sarcocystis isolates from different hosts were subjected to polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analyses using two published DNA markers (25/396 and 33/54). The 334 bp sequence of the 25/396 marker of these isolates and Besnoitia darlingi, B. bennetti, Toxoplasma gondii and Neospora caninum were sequenced and compared. Phylogenetic analysis was performed using neighbour-joining (NJ), maximum parsimony (MP) and minimum evolution (ME) methods based on the sequences of the 25/396 marker of the 13 Sarcocystis isolates obtained in this study and sequences of 10 related isolates from GenBank. Phylogenetic trees revealed a close relatedness among S. neurona isolates in the US (nucleotide sequence diversity <5.0%). US isolates formed a monophyletic group and appeared more closely related to each other than to the South American isolates, which formed a separate lineage. NJ and ME trees with Kimura 2-parameter model separated S. neurona into two separate groups: a northern US group and a Southern US group. These findings suggest a correlation between grouping of the isolates and geographical segregation and were consistent with a genetic bottleneck hypothesis during opossum colonisation of North America. These data do not support either the view of S. neurona as a single super-species or its division into multiple subspecies.     

Effect of peripherally administered ghrelin on gastric emptying and acid secretion in the rat

Ghrelin is a gut peptide that is secreted from the stomach and stimulates food intake. There are ghrelin receptors throughout the gut and intracerebroventricular ghrelin has been shown to increase gastric acid secretion. The aim of the present study was to examine the effects of peripherally administered ghrelin on gastric emptying of a non-nutrient and nutrient liquid, as well as, basal and pentagastrin-stimulated gastric acid secretion in awake rats. In addition, gastric contractility was studied in vitro. Rats equipped with a gastric fistula were subjected to an intravenous infusion of ghrelin (10-500 pmol kg(-1) min(-1)) during saline or pentagastrin (90 pmol kg(-1) min(-1)) infusion. After administration of polyethylene glycol (PEG) 4000 with 51Cr as radioactive marker, or a liquid nutrient with (51)Cr, gastric retention was measured after a 20-min infusion of ghrelin (500 pmol kg(-1) min(-1)). In vitro isometric contractions of segments of rat gastric fundus were studied (10(-9) to 10(-6) M). Ghrelin had no effect on basal acid secretion, but at 500 pmol kg(-1) min(-1) ghrelin significantly decreased pentagastrin-stimulated acid secretion. Ghrelin had no effect on gastric emptying of the nutrient liquid, but significantly increased gastric emptying of the non-nutrient liquid. Ghrelin contracted fundus muscle strips dose-dependently (pD2 of 6.93+/-0.7). Ghrelin IV decreased plasma orexin A concentrations and increased plasma somatostatin concentrations. Plasma gastrin concentrations were unchanged during ghrelin infusion. Thus, ghrelin seems to not only effect food intake but also gastric motor and secretory function indicating a multifunctional role for ghrelin in energy homeostasis.     

Stimulatory effect of endogenous orexin A on gastric emptying and acid secretion independent of gastrin

Orexin A (OXA) increases food intake and inhibits fasting small bowel motility in rats. The aim of this study was to examine the effect of exogenous OXA and endogenous OXA on gastric emptying, acid secretion, glucose metabolism and distribution of orexin immunoreactivity in the stomach. Rats equipped with a gastric fistula were subjected to intravenous (IV) infusion of OXA or the selective orexin-1 receptor (OX1R) antagonist SB-334867-A during saline or pentagastrin infusion. Gastric emptying was studied with a liquid non-nutrient or nutrient, using 51Cr as radioactive marker. Gastric retention was measured after a 20-min infusion of OXA or SB-334867-A. Plasma concentrations of OXA, insulin, glucagon, glucose and gastrin were studied. Immunohistochemistry against OXA, OX1R and gastrin in gastric tissue was performed. OXA alone had no effect on either acid secretion or gastric emptying. SB-334867-A inhibited both basal and pentagastrin-induced gastric acid secretion and increased gastric retention of the liquid nutrient, but not PEG 4000. Plasma gastrin levels were unchanged by IV OXA or SB-334867-A. Plasma OXA levels decreased after intake of the nutrient meal and infusion of the OX1R antagonist. Only weak effects were seen on plasma glucose and insulin by OXA. Immunoreactivity to OXA and OX1R were found in the mucosa, myenteric cells bodies and varicose nerve fibers in ganglia and circular muscle of the stomach. In conclusion, endogenous OXA influences gastric emptying of a nutrient liquid and gastric acid secretion independent of gastrin. This indicates a role for endogenous OXA, not only in metabolic homeostasis, but also in the pre-absorptive processing of nutrients in the gut.     

Viability of glycerol-preserved and cryopreserved anuran skin

Summary Anurans are important animal models for studying the effects of anthropogenic chemical contamination of the environment. Two-compartment Teflon flow-through diffusion cells can be used to study percutaneus absorption of xenobiotics across harvested skin. However, such an approach currently necessitates that skin be harvested just before experimentation, a requirement that calls for the continuous growth and housing of living animals. The ability to preserve and store skin would allow more efficient use of animals and more flexibility in experimental design. To this end, we examined the viability of harvested anuran skin stored under various protocols consistent with current practices of mammalian skin preservation. Skin from the American bullfrog maintained 80–85% viability after 28 d, whereas viability of skin from the marine toad was only maintained for 7–10 d.