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Biomedical subjects

G Blank

Publications and source records attributed to G Blank.

11 recordsLinked to original sources
PubMed2001

Survival of Escherichia coli O157:H7 in frozen foods: impact of the cold shock response.

The survival of Escherichia coli O157:H7 strains in both frozen foods and trypticase soy broth (TSB) was investigated following cold shocking at 10 degrees C for 1.5 h. Using both trypticase soy agar (TSA) and violet red bile agar (VRBA) as recovery media, it was demonstrated that survival levels between cold shocked (CS) and non-cold shocked (NS) E. coli in ground beef or pork were not significantly different (P < or = 0.05). In contrast, cold shocking E. coli in either milk, whole egg or sausage resulted in a significant(P < or = 0.05) enhancement in survival. For milk, survival levels of CS E. coli, by 28 days of frozen storage, were 1.89 and 1.66 log10 cfu/ml higher on TSA and VRBA, respectively, when compared to NS cells. In egg these values were 0.64 and 1.31, while in sausage, values of 0.74 and 1.19 were obtained. In TSB (pH 7) survival of CS E. coli for some strains was about 3 log10 cfu/ml higher when compared to NS cells. Acidification of TSB (pH 5), however, appeared to negate the protective effects of the cold shock treatment. In milk, increasing the differential between the growth and cold shock temperatures resulted in higher numbers of survivors. In this regard the growth-cold shock temperature protocol giving optimum protection was 37-10 degrees C. In contrast, growth of E. coli at 20 degrees C followed by cold shocking at 10 degrees C did not result in any significant freeze protection. In addition, increased protection due to cold shocking was correlated with the appearance of a novel protein appearing at pI 4.8 following isoelectric focusing analysis, thus demonstrating an alteration of protein synthesis.

Animals↗
PubMed1998

Recovery of foodborne microorganisms from potentially lethal radiation damage.

A two-stage recovery protocol was examined for microorganisms following gamma irradiation in phosphate buffer at 0 degrees C. In the first stage, survivors were recovered on basal yeast extract agar and held at various temperatures suboptimal for their growth for 20 h (resuscitation protocol). In the second stage the survivors were incubated for an additional 24 h, but in this case at their optimum temperature for growth. Controls consisted of survivors which were not subjected to the resuscitation protocol (direct incubation at their optimum growth temperature). The ratio of survivors enumerated with and without the resuscitation protocol (control) at each specified temperature was used to formulate a recovery factor(RF). An RF was determined for each treatment dose. Results of this study indicated that the number of Escherichia coli, Salmonella serotype typhimurium and Brochothrix thermosphacta survivors increased following a resuscitation protocol (RF > 2.0). Overall, optimum resuscitation temperatures ranged from 14 to 22 degrees C. The extent of recovery also appeared dose dependent, with larger treatment doses giving rise to a higher RF. S. serotype typhimurium irradiated at 1.5 kGy exhibited the highest RF, 161, when resuscitated at 22 degrees C. Listeria monocytogenes, Yersinia enterocolitica, Staphylococcus aureus, Aeromonas hydrophila and Saccharomyces cerevisiae exhibited an RF < 2.0 regardless of resuscitation temperature. Results of this study indicated that the use of suboptimal holding temperatures as part of a recovery protocol may have advantages, especially with respect to the enumeration of E. coli and salmonellae survivors in irradiated foods such as poultry.

Buffers↗
PubMed1996

Microwave plasmas for low-temperature dry sterilization.

The use of microwave plasmas for dry sterilization has been investigated. The dry-sterilization process is a process similar to plasma etching. Bacteria and viruses can be killed by chemical reactions which disintegrate their bodies and remove them from the surface to be sterilized. The removal of bacteria or viruses from material surfaces is caused by the reaction of activated oxygen species in the plasma with hydrocarbon bonds of the cell wall of the bacteria or the capsid of the viruses. Preliminary experiments indicate that the low-temperature dry sterilization method is easy to use, requires much less time than other methods for sterilization, and is also non-toxic. It is feasible for use in the field of sterilization in dental and medical clinics.

Bacteria↗
PubMed1995

Comparison of resistance of fungal spores to gamma and electron beam radiation.

The irradiation sensitivity of fungal spores to either gamma or electron beam irradiation was evaluated in distilled water. The D10 (the dose required to reduce the initial population by 90%) gamma values ranged from 0.236 to 0.416 kGy and from 0.209 to 0.319 kGy for Penicillium and Aspergillus species, respectively. The D10 electron beam values ranged from 0.194 to 0.341 and from 0.198 to 0.243 kGy for Penicillium and Aspergillus species, respectively. Of the aspergilli species evaluated, only half exhibited significantly (P < 0.05) greater sensitivity to the electron beam treatment compared to gamma irradiation. Four of the six penicillia species evaluated also exhibited significantly (P < 0.05) higher sensitivities to electron beam treatment.

Electrons↗
PubMed1992

Use of electron beam irradiation for mold decontamination on cheddar cheese.

Cheddar cheese slices, surface-inoculated with either Penicillium cyclopium or Aspergillus ochraceus spores, were vacuum packaged and irradiated using an electron beam accelerator. Following treatment at .21 and .52 kGy, the shelf-life of cheese containing P. cyclopium was extended by 3 and 5.5 d, respectively, in comparison with inoculated, untreated samples. Under similar treatment and storage conditions, cheese containing A. ochraceus exhibited average shelf-life extensions of 42.5 and 52.2 d, respectively. Increasing the postirradiation storage temperature to 15 degrees C reduced the shelf-life of cheese, especially with samples containing A. ochraceus. The lowest dose required to inactivate ca. 50 to 60 spores/cm2 of either A. ochraceus or P. cyclopium on the surface of cheese was ca. .42 and .95 kGy, respectively. Irradiation survival curves of A. ochraceus and P. cyclopium spores in cheese yielded average values (the dose required to reduce initial population by 90%) of .21 and .42 kGy, respectively.

Animals↗
PubMedDate not supplied

An assessment of behavioral aging in the Mongolian gerbil.

Male Mongolian gerbils (Meriones unguiculatus) 14-54 months old (n = 77) were evaluated in a battery of psychomotor (open field, locomotor, and runwheel activity, rotorod performance) and learning (one-way active avoidance in a straight runway and in 14-unit T-maze performance) tests. Body weight and seizure activity were also monitored. According to linear regression analysis, runwheel activity decreased with age; and the number of errors in the 14-unit T-maze increased as a function of age (ps < 0.05). None of the other behavioral measures or body weight were significantly correlated with age. This gerbil strain (Tumblebrook Farms; West Brookfield, MA) tended to be very prone to seizures with 64% of the gerbils experiencing at least one seizure while being tested. Seizures tended to occur when the gerbil was exposed to a novel situation (e.g., initial weighing, placement on the rotorod). An age-related decline in some aspects of psychomotor and learning performance was observed, suggesting the gerbil as an additional mammalian model of aging. The high incidence of seizure activity presented a complicating and confounding variable to the interpretation of the results of the behavioral tests used in the present study. Interventions to control seizure activity (e.g., systematic, controlled breeding; adaptation to apparati) in this model will likely increase its viability as a mammalian model of aging.

Aging↗