On the Use of Multiple Probe Insertions at the Same Site for Repeated Intracerebral Microdialysis Experiments in the Nigrostriatal Dopamine System of Rats

The effects of implantation of a dialysis probe into the striatum of awake rats on indices of dopamine (DA) and serotonin neurotransmission were assessed, first over 24 h following initial insertion of a probe, and then again following reinsertion of a probe at the same site 1 week later. It was found that the basal concentration of DA in dialysate stabilized within 20–40 min after probe implantation, although DA showed a modest decline 24 h later. There was, however, no significant difference in basal DA between two test sessions separated by 1 week. On the other hand, the basal concentrations of the DA metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, progressively increased for 2–3 h after probe implantation and decreased markedly by 24 h later. Furthermore, in contrast to DA, the DA metabolites decreased even further after the second probe insertion. Amphetamine-stimulated DA release was also greatly attenuated following the second probe insertion, relative to the first probe insertion. Two probe insertions had only modest effects on the concentration of 5-hydroxyindoleacetic acid in dialysate, relative to the DA metabolites. It is suggested the effects of two probe insertions on DA metabolism and amphetamine-stimulated DA release described here are indicative of probe-induced damage to the nigrostriatal DA system. If this is the case, multiple probe insertions may not provide a feasible strategy for within-subjects design dialysis experiments over extended periods of time, at least in the DA system of small animals. It is suggested further that a stable basal concentration of DA in dialysate may be an especially poor indicator of the integrity of the dopaminergic input to the striatum.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65235/1/j.1471-4159.1992.tb10044.x.pd

Current and prospective pharmacological targets in relation to antimigraine action

Migraine is a recurrent incapacitating neurovascular disorder characterized by unilateral and throbbing headaches associated with photophobia, phonophobia, nausea, and vomiting. Current specific drugs used in the acute treatment of migraine interact with vascular receptors, a fact that has raised concerns about their cardiovascular safety. In the past, α-adrenoceptor agonists (ergotamine, dihydroergotamine, isometheptene) were used. The last two decades have witnessed the advent of 5-HT1B/1D receptor agonists (sumatriptan and second-generation triptans), which have a well-established efficacy in the acute treatment of migraine. Moreover, current prophylactic treatments of migraine include 5-HT2 receptor antagonists, Ca2+ channel blockers, and β-adrenoceptor antagonists. Despite the progress in migraine research and in view of its complex etiology, this disease still remains underdiagnosed, and available therapies are underused. In this review, we have discussed pharmacological targets in migraine, with special emphasis on compounds acting on 5-HT (5-HT1-7), adrenergic (α1, α2, and β), calcitonin gene-related peptide (CGRP 1 and CGRP2), adenosine (A1, A2, and A3), glutamate (NMDA, AMPA, kainate, and metabotropic), dopamine, endothelin, and female hormone (estrogen and progesterone) receptors. In addition, we have considered some other targets, including gamma-aminobutyric acid, angiotensin, bradykinin, histamine, and ionotropic receptors, in relation to antimigraine therapy. Finally, the cardiovascular safety of current and prospective antimigraine therapies is touched upon

Evaluation of the GrovacTM system for decontamination of retail beef trimmings to control E. coli O157:H7 and Salmonella

The Grovac™ intervention system was evaluated for its effectiveness in reducing E. coli O157:H7 and Salmonella inoculated on the surfaces of beef trimmings. Designed to be used in a batch process, the Grovac™ system involves treating beef trimmings in a mixture of citric acid and a hypotonic salt solution while tumbling under vacuum. Beef trimmings were inoculated with a five-strain cocktail of E. coli O157:H7 and Salmonella, then subjected to no treatment, water with a 1-hour drain treatment, water with an overnight drain treatment, Grovac™ with a 1-hour drain treatment, and Grovac™ with an overnight drain treatment. Data indicated that the Grovac™ system may be a viable method for retailers to use with in-house beef grinding operations to reduce E. coli O157:H7 and Salmonella risks. Reductions in these pathogen populations were 85 and 80%, respectively, after draining for 18 hours at 36°F

Effects of media type on Shiga toxigenic E. coli growth patterns

Escherichia coli O157:H7 was declared to be an adulterant in raw ground beef in 1994 by the United States Department of Agriculture Food Safety and Inspection Service following a large and deadly foodborne disease outbreak in the Pacific Northwest involving undercooked hamburgers sold at Jack-in-the-Box restaurants. Due to their recognition as significant human foodborne pathogens, six additional strains (serotypes) of Shiga toxin-producing E. coli (STEC) were also deemed to be adulterants in raw beef products in 2012. The beef processing industry has worked diligently since the mid-1990s to control the presence of E. coli O157:H7 in finished raw products through the implementation of aggressive microbial testing programs and the incorporation of antimicrobial intervention technologies validated to substantially reduce the presence of this pathogenic organism. This effort has occurred within the framework of Hazard Analysis and Critical Control Points (HACCP) programs. With the addition of six additional STEC strains that also must be controlled through these programs, laboratory-testing methods must be developed and implemented to afford the industry a means to accurately document their control programs. Shiga toxin-producing E. coli cultivation, identification, and quantification methods are currently lacking. Establishing behavior patterns for these STECs will allow the beef processing industry to better develop methods for controlling or eliminating them in the food supply. To accomplish this, the prevalence of these organisms must first be established through sampling, but research into which media type is best for enriching samples to recover and identify all STEC organisms has been limited. To determine which media type was best suited for recovery of STECs, we inoculated multiple enrichment media types with the target strains and observed their growth patterns

Steam pasteurization of beef carcasses

This research evaluated the effectiveness of a newly patented steam-pasteurization process for reducing bacterial populations on the surfaces of freshly slaughtered beef carcasses. The process was developed jointly by Frigoscandia Food Processing Systems (Bellevue, WA) and Excel Corp. (Wichita, KS), a division of Cargill (Minneapolis, MN). In laboratory studies, portions of prerigor beef carcasses inoculated with very high levels of three pathogens, Salmonella, Escherichia coli O157:H7, and Listeria, were treated in a prototype steam-pasteurization chamber, which effectively eliminated at least 99.9% of all three pathogens and was most effective when used in combination with other standard commercial decontamination methods. The effectiveness of a full-scale, automated, steam-pasteurization system was evaluated in a commercial beef slaughter facility. The commercial system was very effective, reducing the naturally occurring overall bacterial population by over 90% and reducing the population of E. coli (nonpathogenic) and related organisms to undetectable levels. Steam pasteurization is very effective at reducing bacterial contamination on unchilled beef carcasses and should be viewed as one step in an overall process of reducing the risk of pathogenic bacteria in beef and beef products

Steam pasteurization of commercially slaughtered beef carcasses: Evaluation of bacterial populations at five anatomical locations

A steam pasteurization process (patent pending) has been shown to effectively reduce pathogenic bacterial populations on beef tissue and to significantly reduce naturally occurring bacterial populations on commercially slaughtered beef carcasses. The objective of this study was to determine the effectiveness of the steam pasteurization treatment for reducing bacterial populations at several anatomical locations on commercially slaughtered carcasses. Before and after pasteurization treatment (82.2°C, 6.5-s exposure time), a sterile sponge was used to sample 300 cm2 at one of five locations (inside round, loin, midline, brisket, or neck). Eighty carcasses (40 before treatment and 40 after treatment) were sampled per anatomical location over 2 processing days. Before treatment, aerobic plate counts (APCs) were found to be highest (P ≤ 0.01) at the midline (4.5 log10 CFU/100 cm2), intermediate at the inside round, brisket, and neck (ca. 3.8 log10 CFU/100 cm2), and lowest at the loin (3.4 log10 CFU/100 cm2). After treatment, APCs at all locations were reduced significantly (P ≤ 0.01). The inside round, loin, and brisket had the lowest (P ≤ 0.01) APCs (ca. 2.6 log10 CFU/100 cm2), whereas the midline and neck had APCs of 3.1 and 3.3 log10 CFU/100 cm2, respectively. The lower reduction in APCs at the neck area indicated that the treatment may not be as effective there, possibly because of the design of the pasteurization equipment. Generic Escherichia coli populations were low at all locations before treatment, with populations on 32% of all carcasses sampled being less than the detection limit of the study (5.0 CFU/100 cm2). After treatment, E. coli populations were significantly lower (P ≤ 0.01) than populations before treatment and 85% of all carcasses sampled had E. coli populations below the detection limit. The maximum E. coli population detected after treatment was 25 CFU/100 cm2. For enteric bacterial populations, no differences were observed in the effectiveness of the treatment among the five carcass locations

Comparison of steam pasteurization and other methods for reduction of pathogens on surfaces of freshly slaughtered beef

The effectiveness of a recently invented "steam pasteurization" (S) process in reducing pathogenic bacterial populations on surfaces of freshly slaughtered beef was determined and compared with that of other standard commercial methods including knife trimming (T), water washing (35°C; W), hot water/steam vacuum spot cleaning (V), and spraying with 2% vol/vol lactic acid (54°C, pH 2.25; L). These decontamination treatments were tested individually and in combinations. Cutaneus trunci muscles from freshly slaughtered steers were inoculated with feces containing Listeria monocytogenes Scott A, Escherichia coli O157:H7, and Salmonella typhimurium over a predesignated meat surface area, resulting in initial populations of ca. 5 log CFU/cm2 of each pathogen. Tissue samples were excised from each portion before and after decontamination treatments, and mean population reductions were determined. Treatment combinations evaluated were the following (treatment designations within the abbreviations indicate the order of application): TW, TWS, WS, VW, VWS, TWLS, and VWLS. These combinations resulted in reductions ranging from 3.5 to 5.3 log CFU/cm2 in all three pathogen populations. The TW, TWS, WS, TWLS, and VWLS combinations were equally effective (P > 0.05), resulting in reductions ranging from 4.2 to 5.3 log CFU/cm2. When used individually, T, V, and S resulted in pathogen reductions ranging from 2.5 to 3.7 log CFU/cm2 Steam pasteurization consistently provided numerically greater pathogen reductions than T or V. Treatments T, V, and S were all more effective than W (which gave a reduction on the order of 1.0 log CFU/cm2) Steam pasteurization is an effective method for reducing pathogenic bacterial populations on surfaces of freshly slaughtered beef, with multiple decontamination procedures providing greatest overall reductions