Predictive model for reduction of Escherichia coli during acetic acid decontamination of chicken skin

AIMS: The response surface methodology was used to evaluate the effect of operating variables (acetic acid concentration, spraying time and temperature) on the reduction of Escherichia coli populations on poultry breast skin in a laboratory showering process, as well as to identify the best conditions that are required to develop this operation. METHODS AND RESULTS: Skin samples were inoculated with a 24-h E. coli culture and afterwards treated according to experimental design under selected acetic acid concentration, spraying time, and solution temperature. The E. coli reduction model was significantly affected by the acetic acid concentration and spraying time (P < or = 0.05 and < or =0.01), while temperature did not show a significant effect (P > 0.05). CONCLUSION: The predictive model obtained was validated through additional confirmatory experiments and showed to be adequate, and it could be used as an approach to optimize the acetic acid spray washes during poultry carcasses processing. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of acetic acid washes in the processing of poultry does not have the capability of eliminating E. coli populations from carcasses. However, significant reductions in the initial load could be achieved.     

The effect of copper on the death rate of Salmonella typhimurium DT104:30 in food substrates acidified with organic acids

AIMS: The objective of this study was to investigate the effect of copper ions on the survival of Salmonella typhimurium DT104:30 in acidified liquid food substrates. METHODS AND RESULTS: The decimal reduction time (Dvalue) of Salm. typhimurium DT104:30 was determined in acidified liquid pig feed (LPF) and skimmed milk (SM) containing a range of copper concentrations (0-50 ppm). As copper concentration increased, the death rate of Salm. typhimurium DT104:30 increased. In LPF acidified with 150 mmol l-1 lactic acid the presence of 50 ppm copper resulted in a 10-fold increase in the death rate. CONCLUSIONS: The presence of copper salts in acidic liquid food substrates significantly increases the death rate of Salm. typhimurium DT104:30. SIGNIFICANCE AND IMPACT OF THE STUDY: This finding could influence policy on levels of copper in pig feed.     

Application of antimicrobial ice for reduction of foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes) on the surface of fish

AIMS: The efficacy of antimicrobial ice was evaluated for the reduction of foodborne pathogens on the surface of fish. METHODS AND RESULTS: Antimicrobial ice containing chlorine dioxide (ClO2) was utilized to control foodborne pathogens in laboratory media and on fish skin. Escherichia coli O157:H7, Salmonella serotype Typhimurium and Listeria monocytogenes strains were treated with antimicrobial ice for 30 min on plates of selective agar and for 120 min on fish skin at room temperature, and then incubated for enumeration. After treatment with 100 ppm ClO2 for 30 min, 5.4, 4.4 and 3.2 log10 reduction was obtained with E. coli O157:H7, Salm. Typhimurium and L. monocytogenes on laboratory media, respectively. When antimicrobial ice (100 ppm ClO2) was applied to fish skin for 120 min, total reduction of E. coli O157:H7, Salm. Typhimurium and L. monocytogenes was 4.8, 2.6 and 3.3 log10, respectively. CONCLUSION: The initial load of foodborne pathogens was reduced by antimicrobial ice and the lowered microbial level was maintained during treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: The application of antimicrobial ice is a simple and effective method for the safe preservation of fish.     

Competitive exclusion against Salmonella Enteritidis in layer chickens by yoghurt microbiota: impact on egg production, protection and yolk-antibody and cholesterol levels

AIMS: This work aims at studying the impact of competitive exclusion of Salmonella serotype Enteritidis infection in layer chickens, by microbiota of fresh and dried-modified yoghurt, on egg production and weight, protection against infection, and on yolk-antibody and cholesterol levels. METHODS AND RESULTS: Four groups of 27-week-old layer chickens were included in this study. After an initial enrofloxacin treatment, groups 1 and 2 were administered fresh or dry yoghurt (respectively) for 14 days. Groups 1, 2 and 3 were challenged intraoesophageally with Salm. Enteritidis, on the sixth day of yoghurt administration, while group 4 was left unchallenged and without yoghurt administration. No significant difference in percent infectivity of visceral organs with Salm. Enteritidis was observed between the groups. The yoghurt administered groups showed an early significant antibody response in their yolk on the seventh day postchallenge (P < 0.05) and highest egg production and weight. Finally, the egg yolk cholesterol concentration was higher in Salm. Enteritidis-challenged groups than that observed in the unchallenged group. CONCLUSIONS: The results point to the possible involvement of yoghurt administration in immunopotentiation and improvement of egg production and weight. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings warrant further research that could improve immunity and production in layer chickens infected with Salm. Enteritidis.     

Identification of Salmonella enteritidis outer membrane proteins expressed during attachment to human intestinal epithelial cells

AIMS: To express and identify the Salmonella enterica ser. Enteritidis outer membrane proteins that are involved in the attachment to human intestinal epithelial cells. METHODS AND RESULTS: Salmonella Enteritidis attachment proteins were expressed by infection of human intestinal epithelial cells (int-407) with Salm. Enteritidis strain SE28, followed by pulse labelling with [35S]-methionine. Outer membrane proteins were separated by TritonX-114 phase partitioning, and were detected by Salm. Enteritidis-specific polyclonal antibody. Outer membrane proteins of molecular weights 82.3, 75.6, 49.3, 35.5 and 19.3 kDa were newly synthesized. Expression of 31.2 and 16 kDa proteins was up-regulated, whereas the expression of 40.7 kDa protein was down-regulated. Polyclonal antibodies against the 82.3 and 75.6 kDa proteins significantly (P < 0.05) reduced the binding of Salm. Enteritidis to int-407 cells in vitro. CONCLUSIONS: Outer membrane proteins 82.3 and 75.6 kDa are potentially involved in the attachment of Salm. Enteritidis to the intestinal mucosa. SIGNIFICANCE AND IMPACT OF THE STUDY: Outer membrane proteins 82.3 and 75.6 kDa identified in this study could be used as potential vaccines to block or reduce Salm. Enteritidis colonization in chickens.     

Differential response to DNA damage may explain different cancer susceptibility between small and large intestine

Although large intestine (LI) cancer is the second-leading cause of cancer-related deaths in the United States, small intestine (SI) cancer is relatively rare. Because oxidative DNA damage is one possible initiator of tumorigenesis, we investigated if the SI is protected against cancer because of a more appropriate response to oxidative DNA damage compared with the LI. Sixty rats were allocated to three treatment groups: 3% dextran sodium sulfate (DSS, a DNA-oxidizing agent) for 48 hrs, withdrawal (DSS for 48 hrs + DSS withdrawal for 48 hrs), or control (no DSS). The SI, compared with the LI, showed greater oxidative DNA damage (P < 0.001) as determined using a quantitative immunohistochemical analysis of 8-oxodeoxyguanosine (8-oxodG). The response to the DNA adducts in the SI was greater than in the LI. The increase of TdT-mediated dUTP-biotin nick end labeling (TUNEL)-positive apoptosis after DSS treatment was greater in the SI compared with the LI (P < 0.001), and there was a positive correlation (P = 0.031) between DNA damage and apoptosis in the SI. Morphologically, DSS caused an extensive loss of crypt structure shown in lower crypt height (P = 0.006) and the number of intact crypts (P = 0.0001) in the LI, but not in the SI. These data suggest that the SI may be more protected against cancer by having a more dynamic response to oxidative damage that maintains crypt morphology, whereas the response of the LI makes it more susceptible to loss of crypt architecture. These differential responses to oxidative DNA damage may contribute to the difference in cancer susceptibility between these two anatomic sites of the intestine.     

Aerosolization as novel sanitizer delivery system to reduce food-borne pathogens

AIMS: As a preliminary experiment on new sanitizer delivery tools, the efficacy of aerosolized sanitizer on food-borne pathogens was investigated in larger model chamber system. METHODS: Peroxyacetic acid and hydrogen peroxide were aerosolized in a model system against artificially inoculated target micro-organisms on laboratory media. Cultures of four different food-borne pathogens were inoculated and affixed onto three different heights (bottom, wall and ceiling), and three different orientations (face-down, vertical and face-down) inside a commercial semi-trailer cabinet (14.6 x 2.6 x 2.8 m). Sanitizer was aerosolized into 2 microm droplet size fog and treated for 1 h at ambient temperature. RESULTS: Populations of Bacillus cereus, Listeria innocua, Staphylococcus aureus, and Salmonella typhimurium were reduced by an average of 3.09, 7.69, 6.93 and 8.18 log units per plate respectively. Interestingly, L. innocua, Staph. aureus, and Salm. typhimurium showed statistically not different (P >/= 0.05) reduction patterns relative to height and orientation that were never expected in a spraying system. CONCLUSIONS: Aerosolized sanitizers diffuse like gaseous sanitizers. SIGNIFICANCE AND IMPACT OF THE STUDY: Aerosolization has great potential for use in commercial applications.     

Activity of natural antimicrobial compounds against Escherichia coli and Salmonella enterica serovar Typhimurium

AIMS: The objective of this study was to evaluate the inhibitory activity of several natural organic compounds alone or in combination with nisin against Escherichia coli and Salmonella Typhimurium. METHODS AND RESULTS: The minimum inhibitory concentration (MIC) of five natural organic compounds were determined, and the effect of their combinations with nisin was evaluated by the checkerboard assay using the Bioscreen C. As expected, nisin by itself showed no inhibition against either of the Gram-negative bacteria. Thymol was found to be the most effective with the lowest MIC values of 1.0 and 1.2 mmol 1-1 against Salm. Typhimurium and E. coli, respectively. After thymol, the antimicrobial order of the natural organic compounds was carvacrol > eugenol > cinnamic acid > diacetyl. However, the combination of nisin with the natural organic compounds did not result in the enhancement of their antimicrobial activities. On the contrary, combination of nisin with diacetyl against Salm. Typhimurium resulted in an antagonism of diacetyl activity. CONCLUSIONS: While the individual natural organic compounds showed inhibitory activity against the two Gram-negatives, their combinations with nisin showed no improvement of antimicrobial activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows the potential of the natural organic compounds to control E. coli and Salm. Typhimurium.     

Evaluation of steam pasteurization in controlling Salmonella serotype Enteritidis on raw almond surfaces

Aim: To investigate the efficacy of steam pasteurization for reducing Salmonella serotype Enteritidis on raw almond surfaces. Methods and Results: Nonpareil almonds were inoculated to 10^7–8 CFU g^?1 with a Salm. Enteritidis cocktail (Salm. Enteritidis 43353, ME‐13, ME‐14) or Salm. Enteritidis phage type 30, dried overnight and subjected to steam treatments through a pilot‐sized vertical pasteurization machine for 5, 15, 25, 35, 45, 55 and 65 s to investigate the effect of steam on a single layer of almond. Survival of Salm. Enteritidis was evaluated with tryptic soy agar and xylose lysine desoxycholate overlay for total and healthy cells, respectively. No significant differences (P > 0·05) in reduction were observed between the Salm. Enteritidis cocktail and Salm. Enteritidis PT 30 inoculum. Reduction of Salm. Enteritidis increased as a function of treatment time, with 25 s being sufficient to achieve a 5‐log reduction. Discolouration and visible formation of wrinkles were observed following steam pasteurization of more than 35 s. Conclusions: Steam pasteurization of 25 s is sufficient to achieve a 5‐log reduction of Salm. Enteritidis inoculated on raw almonds without visual quality degradation. Significance and Impact of the Study: Steam pasteurization is an effective alternative to reduce or prevent Salm. Enteritidis contamination on raw almonds.     

Effects of storage and the presence of a beef microflora on the thermal resistance of Salmonella Typhimurium DT104 in beef and broth systems

AIMS: To investigate the effects of storage and the presence of a beef microflora on the thermal resistance of Salmonella serotype Typhimurium DT104 on beef surfaces and in a broth system during subsequent heat treatments after extended low-temperature storage (4 degrees C for 14 days) or mild temperature abuse (10 degrees C for 7 days). METHODS AND RESULTS: Surviving Salm. Typhimurium DT104 cells were estimated after heating in a water bath (55 degrees C) by plating beef and broth samples on tryptone soya agar and overlaying with xylose-lysine-deoxycholate agar. In beef and broth systems, D(55) values for Salm. Typhimurium DT104 stored at 4 degrees C or 10 degrees C in the presence or absence of a beef microflora were significantly lower (P < 0.01) than the D values for this organism heat-treated immediately after inoculation. In beef systems, the D(55) values were significantly lower (P < 0.05) in the presence of a beef microflora than the D(55) values obtained in 'pure' culture under all temperature/storage combinations. However, in broth systems, there was no significant difference between the D(55) values obtained in 'pure' culture and the D(55) values obtained from systems containing beef microflora. CONCLUSIONS: Storage of Salm. Typhimurium DT104 significantly reduced the thermal resistance of the pathogen in beef and broth systems. In the presence of high numbers of a Gram-negative beef microflora, the heat sensitivity of the pathogen was further increased on beef surfaces but not in broth. SIGNIFICANCE AND IMPACT OF THE STUDY: Studies investigating the survival of Salm. Typhimurium DT104 in different food systems will help define safe food preservation processes and will aid in the elimination this pathogen from the food production environments.     

Prevalence of bacterial faecal pathogens in separated and unseparated stored pig slurry

AIMS: To examine the prevalence and diversity of bacterial faecal pathogens in unseparated slurry, separated solids and liquid fractions from a commercial pig farm. METHODS: A total of 43 stored slurry specimens originating from a fattening house over the period February-April 2002 were analysed, consisting of unseparated (n = 14) slurry, separated solids (n = 16) and separated liquid (n = 13). Specimens were examined for the presence of five bacterial pathogens including Salmonella spp., Shigella spp., Campylobacter spp., Escherichia coli O157 and Yersinia enterocolitica. Selective enrichment and plating methods were employed for detection of Salmonella spp. and Campylobacter spp. and conventional selective plating techniques for the remaining genera. Antibiogram profiles to 12 antibiotic agents were obtained for all Salmonella isolates obtained. RESULTS: Salmonella spp. were identified in all components of the slurry specimens, whereas Campylobacter spp. was only recovered from the unseparated and separated liquid fractions. In both cases, the separated liquid fraction had the highest prevalence of pathogens and the separated solid fraction had the lowest prevalence. None of the slurry specimens examined were positive for E. coli O157:H7, Shigella spp. or Y. enterocolitica. Twenty-nine isolates of Salmonella were recovered from the slurry specimens, comprising seven serovars, of which Salmonella manhattan was the most prevalent, accounting for over half [15 of 29 (51.7%)] of all Salmonella isolates. Salmonella anatum, Salm. derby, Salm. give, Salm. heidelberg, Salm. simi and Salm. stanley serovars were also recovered. All Salmonella isolates were sensitive to ampicillin, augmentin (amoxicillin/clavulanic acid), chloramphenicol, ciprofloxacin, gentamicin, kanamycin and trimethoprim, but has variable resistance to tetracycline (100%), sulphonamides (84.6%), furazolidone (38.5%), nalidixic acid (15.4%) and streptomycin (15.4%). The majority (57.7%) of isolates displayed antibiotic resistance to at least two antibiotic agents, followed by 34.6% of isolates being resistant to three agents and the remainder (7.7%) being resistant to four antibiotics. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated a marked reduction in the prevalence of Campylobacter and Salmonella in the solids component of separated pig slurry. The adoption of control processes such as aeration of slurry prior to its spread onto agricultural land and newer approaches to pathogen reduction should be investigated, to reduce the transmission of pathogens from pig slurry to the environment.     

Concentration effect of Riesling Icewine juice on yeast performance and wine acidity

AIMS: The objective of this study was to determine the effect of increasing juice soluble solids above 40 degrees Brix on wine yeast's ability to grow and ferment the juice, with particular focus on acetic acid production, titratable acidity (TA) changes and the maximum amount of sugar consumed by the yeast. METHODS AND RESULTS: Riesling Icewine juices at 40, 42, 44 and 46 degrees Brix were inoculated with K1- V116 at 0.5 g 1(-1) and fermented at 17 degrees C until sugar consumption ceased. Increasing soluble solids showed strong negative linear correlations with yeast growth, sugar consumption and ethanol production (r = -0.999, -0.997 and 0.984, P < 0.001, respectively). Acetic acid, glycerol and TA production normalized to sugar consumed showed strong positive correlations to the initial juice concentration (r = 0.992, 0.963, and 0.937, P < 0.001 respectively) but no correlation was found for ethanol production. The acetic acid produced as a function of sugar consumed was positively correlated to the glycerol produced (r = 0.970, P < 0.001). The final TA of the wines ranged between 11.8 and 13.7 g 1(-1) tartaric acid, increasing by 2.3-3 g 1(-1) over the starting juice. The increase in TA was positively correlated to the increase in acetic acid produced after normalizing the data to the amount of sugar consumed (r =0.975, P < 0.001). The acid equivalents resulting from the increase in acetic acid accounted for 80-100% of the TA increase when converted to units of tartaric acid. In the final Icewines, acetic acid represented 19-20% of wine TA. CONCLUSIONS: Increasing Icewine juice concentration from 40 to 46 degrees Brix increases the proportion of yeast sugar metabolism towards glycerol and acetic acid production to cope with the increased osmotic stress by decreasing yeast growth, sugar consumption rate, the total amount of sugar consumed and the total amount of ethanol produced. The high proportional contribution of acetic acid to titratable acidity in Riesling Icewine may affect acidity perception. SIGNIFICANCE AND IMPACT OF THE STUDY: We have determined that 10% v/v ethanol would not be achievable with initial juice concentrations above 42 degrees Brix and that Riesling Icewine juice above 52.5 degrees Brix would be theoretically unfermentable. The high proportional contribution of acetic acid to TA may be an important factor in the organoleptic balance of these Icewines.     

Investigations on anti-Aspergillus properties of bacterial products

AIMS: To investigate the anti-Aspergillus properties of bacterial products. METHODS AND RESULTS: In the present study, 12 bacterial strains were screened for antifungal activity against Aspergilli. The culture supernatant and lysates of Pseudomonas aeruginosa, Bacillus cereus, Escherichia coli (BL21, DH5alpha, HB101, XL Blue), Klebsiella pneumoniae, Streptomyces thermonitrificans, Streptococcus pneumoniae, Enterobacter aerogenes, Staphylococcus aureus and Salmonella typhi were examined for antifungal activity in protein concentration ranging from 1000.0 to 7.8 microg ml-1 using microbroth dilution assay. The lysate of Salm. typhi and E. coli BL21 exhibited the maximum activity against Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger. Their in vitro minimum inhibitory concentrations (MICs) were found to be 15.6-31.2 microg ml-1 by microbroth dilution and spore germination inhibition assays. In disc diffusion assay, a concentration of 3.1 microg disc-1 of Salm. typhi lysate showed significant activity against Aspergilli. Escherichia coli BL21 exhibited similar activity at 6.2 microg disc-1. The work on identification of molecule endowed with antimycotic properties is in progress. CONCLUSION: The products of Salm. typhi and E. coli demonstrated significant activity against Aspergillus species. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first time that E. coli has been reported for anti-Aspergillus activity. It could be an important source of biologically active compounds useful for developing better new antifungal drugs/or probiotics.     

Effect of high pressure and pasteurization on Mycobacterium avium ssp. paratuberculosis in milk

AIMS: To determine the effect of high pressures alone and in conjunction with pasteurization on the viability of two strains of Mycobacterium avium ssp. paratuberculosis (Map). METHODS AND RESULTS: Map in a milk matrix was subjected to 400, 500 and 600 MPa with and without pasteurization (72 degrees C for 15 s) and plated onto Herrold's egg yolk medium (HEYM) and Middlebrook 7H10 (7H10) agar, both containing antibiotic supplements. Medium 7H10 was found to give a significantly (P < 0.001) better recovery than HEYM. A significantly greater (P < 0.001) reduction in viable numbers was observed using 500 MPa (mean log reduction of 6.52) compared with 400 MPa (mean log reduction of 2.56) and between 400 MPa and control (no applied pressure) for 10 min treatments. A treatment time of 10 min resulted in significantly (P < 0.001) fewer survivors than 5 min. Low numbers of survivors were still detected when pressure treatment at 400 and 600 MPa was combined with subsequent pasteurization. CONCLUSIONS: The use of high-pressure was effective in reducing viable numbers of Map but even when combined with pasteurization there were still survivors, albeit when high inoculum levels of Map were used. SIGNIFICANCE AND IMPACT OF THE STUDY: To the authors' knowledge the work reported here represents the first study of the efficacy of high-pressure treatments alone and in combination with pasteurization to kill Map. The results indicate that further research is warranted before more commercial-scale studies are commissioned.     

The impact of baseline artery diameter on flow-mediated vasodilation: a comparison of brachial and radial artery responses to matched levels of shear stress

An inverse relationship between baseline artery diameter (BAD) and flow-mediated vasodilation (FMD) has been identified using reactive hyperemia (RH) to create a shear stress (SS) stimulus in human conduit arteries. However, RH creates a SS stimulus that is inversely related to BAD. The purpose of this study was to compare FMD in response to matched levels of SS in two differently sized upper limb arteries [brachial (BA) and radial (RA) artery]. With the use of exercise, three distinct, shear rate (SR) stimuli were created (SR = blood velocity/vessel diameter; estimate of SS) in the RA and BA. Artery diameter and mean blood velocity were assessed with echo and Doppler ultrasound in 15 healthy male subjects (19-25 yr). Data are means ± SE. Subjects performed 6 min of adductor pollicis and handgrip exercise to increase SR in the RA and BA, respectively. Exercise intensity was modulated to achieve uniformity in SR between arteries. The three distinct SR levels were as follows: steady-state exercise 39.8 ± 0.6, 57.3 ± 0.7, and 72.4 ± 1.2 s(-1) (P < 0.001). %FMD and AbsFMD (mm) at the end of exercise were greater in the RA vs. the BA at each shear level [at the highest level: RA = 15.7 ± 1.5%, BA = 5.4 ± 0.8% (P < 0.001)]. The mean slope of the within-subject SR-%FMD regression line was greater in the RA (RA = 0.33 ± 0.04, BA = 0.13 ± 0.02, P < 0.001), and a strong within-subjects relationship between %FMD and SR was observed in both arteries (RA: r(2) = 0.92 ± 0.02; BA: r(2) = 0.90 ± 0.03). Within the RA, there was a significant relationship between baseline diameter and %FMD; however, this relationship was not present in the BA (RA: r(2) = 0.76, P < 0.001; BA: r(2) = 0.03, P = 0.541). These findings suggest that the response to SS is not uniform across differently sized vessels, which is in agreement with previous studies.     

Effect of continuous ohmic heating to inactivate Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in orange juice and tomato juice

Aims: The purpose of this study was to investigate the efficacy of continuous ohmic heating for reducing Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in orange juice and tomato juice. Methods and Results: Orange juice and tomato juice were treated with electric field strengths in the range of 25–40 V cm^?1 for different treatment times. The temperature of the samples increased with increasing treatment time and electric field strength. The rate of temperature change for tomato juice was higher than for orange juice at all voltage gradients applied. Higher electric field strength or longer treatment time resulted in a greater reduction of pathogens. Escherichia coli O157:H7 was reduced by more than 5 log after 60‐, 90‐ and 180‐s treatments in orange juice with 40, 35 and 30 V cm^?1 electric field strength, respectively. In tomato juice, treatment with 25 V cm^?1 for 30 s was sufficient to achieve a 5‐log reduction in E. coli O157:H7. Similar results were observed in Salm. Typhimurium and L. monocytogenes. The concentration of vitamin C in continuous ohmic heated juice was significantly higher than in conventionally heated juice (P < 0·05). Conclusions: Continuous ohmic heating can be effective in killing foodborne pathogens on orange juice and tomato juice with lower degradation of quality than conventional heating. Significance and Impact of the Study: These results suggest that continuous ohmic heating might be effectively used to pasteurize fruit and vegetable juices in a short operating time and that the effect of inactivation depends on applied electric field strengths, treatment time and electric conductivity.     

Insights into a role of GH secretagogues in reversing the age-related decline in the GH/IGF-I axis

Growth hormone (GH) secretion and serum insulin-like growth factor-I (IGF-I) decline with aging. This study addresses the role played by the hypothalamic regulators in the aging GH decline and investigates the mechanisms through which growth hormone secretagogues (GHS) activate GH secretion in the aging rats. Two groups of male Wistar rats were studied: young-adult (3 mo) and old (24 mo). Hypothalamic growth hormone-releasing hormone (GHRH) mRNA and immunoreactive (IR) GHRH dramatically decreased (P < 0.01 and P < 0.001) in the old rats, as did median eminence IR-GHRH. Decreases of hypothalamic IR-somatostatin (SS; P < 0.001) and SS mRNA (P < 0.01), and median eminence IR-SS were found in old rats as were GHS receptor and IGF-I mRNA (P < 0.01 and P < 0.05). Hypothalamic IGF-I receptor mRNA and protein were unmodified. Both young and old pituitary cells, cultured alone or cocultured with fetal hypothalamic cells, responded to ghrelin. Only in the presence of fetal hypothalamic cells did ghrelin elevate the age-related decrease of GH secretion to within normal adult range. In old rats, growth hormone-releasing peptide-6 returned the levels of GH and IGF-I secretion and liver IGF-I mRNA, and partially restored the lower pituitary IR-GH and GH mRNA levels to those of young untreated rats. These results suggest that the aging GH decline may result from decreased GHRH function rather than from increased SS action. The reduction of hypothalamic GHS-R gene expression might impair the action of ghrelin on GH release. The role of IGF-I is not altered. The aging GH/IGF-I axis decline could be rejuvenated by GHS treatment.     

Enhanced transdermal delivery of salbutamol sulfate via ethosomes

The main objective of the present work was to compare the transdermal delivery of salbutamol sulfate (SS), a hydrophilic drug used as a bronchodilator, from ethosomes and classic liposomes containing different cholesterol and dicetylphosphate concentrations. All the systems were characterized for shape, particle size, and entrapment efficiency percentage, by image analysis optical microscopy or transmission electron microscopy, laser diffraction, and ultracentrifugation, respectively. In vitro drug permeation via a synthetic semipermeable membrane or skin from newborn mice was studied in Franz diffusion cells. The selected systems were incorporated into Pluronic F 127 gels and evaluated for both drug permeation and mice skin deposition. In all systems, the presence of spherical-shaped vesicles was predominant. The vesicle size was significantly decreased (P < .05) by decreasing cholesterol concentration and increasing dicetylphosphate and ethanol concentrations. The entrapment efficiency percentage was significantly increased (P < .05) by increasing cholesterol, dicetylphosphate, and ethanol concentrations. In vitro permeation studies of the prepared gels containing the selected vesicles showed that ethosomal systems were much more efficient at delivering SS into mice skin (in terms of quantity and depth) than were liposomes or aqueous or hydroalcoholic solutions.     

Reduction of Salmonella on alfalfa seeds using peroxyacetic acid and a commercial seed washer is as effective as treatment with 20 000 ppm of Ca(OCl)2

Aims: The efficacy of a commercial seed washer and 1 and 3% peroxyacetic acid or 20 000 ppm calcium hypochlorite for reducing Salmonella on alfalfa seeds was investigated. Methods and Results: Alfalfa seeds were inoculated with Salmonella Stanley to achieve c. 5 log CFU g^?1. Seeds were then treated with 1 or 3% peroxyacetic acid or 20 000 ppm calcium hypochlorite for 15 min in a commercial seed washer that uses air to enhance contact of the sanitizer with the seed. Experiments were also conducted using industry and laboratory methods. An c. 1‐log reduction in number of Salm. Stanley was demonstrated regardless of the chemical treatment or method of treatment. Although this 1‐log reduction was significant (P < 0·05), differences among the treatments were not significant. Treating the seed with 1 and 3% peroxyacetic acid resulted in similar Salm. Stanley reductions of 1·77 and 1·34 log, respectively, not being statistically significant (P > 0·05). Conclusions: These results suggest that under conditions tested, 1 or 3% peroxyacetic acid solutions are equally effective as 20 000 ppm of Ca(OCl)₂ in the reduction of Salm. Stanley on alfalfa seed when used in conjunction with a commercial seed washer. Significance and Impact of the Study: A 1% peroxyacetic acid solution could potentially be used in place of 20 000 ppm of Ca(OCl)₂ for treatment of seeds used for sprouting_. The commercial seed washer did not enhance removal of Salm. Stanley from alfalfa seeds, but did facilitate removal of excess soil from seeds.     

Sanitation of faeces from source-separating dry toilets using urea

Aim:  To develop a reliable and simple method to produce safe fertilizers from human excreta using urea for sanitation of faeces.
Methods and Results:  Urea was added to faecal matter (17% dry matter) at concentrations of 0·5–2% (w/w) and inactivation of Salmonella enterica subspecies 1 serovar Typhimurium (Salm. Typhimurium), Enterococcus spp . and the Salm. Typhimurium bacteriophage 28B was monitored at 14, 24 and 34°C. Urea additions enhanced inactivation and inactivation rates were positively related to increasing NH₃ (aq) concentration and temperature. Salm. Typhimurium was the most sensitive of the organisms studied, while Enterococcus spp. showed more persistence, especially at lower temperatures. The bacteriophage was the most resistant organism studied.
Conclusions:  Salmonella reduction levels that meet requirements for safe reuse of faeces as fertilizer (i.e. 6 log₁₀ reduction) can be achieved for 1% urea within 2 months at 14°C or within 1 week at 24°C and 34°C.
Significance and Impact of the Study:  The relationships between organism inactivation rates and temperature, ammonia and pH were identified. Urea treatment proved to be a robust and efficient option for safe recycling of plant nutrients.