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J A Hudson

Publications and source records attributed to J A Hudson.

At least 55 records · Page 3Linked to original sources
PubMed1993

Construction and comparison of response surface kinetic models for the Yersinia enterocolitica type strain and a food isolate under aerobic conditions.

Response surface models were constructed for the type strain of Yersinia enterocolitica (ATCC 9610) and a wild type strain isolated from sliced roast lamb, for various conditions of temperature, pH, sodium chloride concentration and sodium nitrite concentration. Both strains grew at similar rates except at the 'extremes' of the conditions tested. Models for both quadratic and cubic polynomial equations are shown. The results obtained indicate that the cubic model is superior.

Aerobiosis↗
PubMed1993

Growth of Listeria monocytogenes, Aeromonas hydrophila and Yersinia enterocolitica in pâté and a comparison with predictive models.

A reference or type strain and a food derived-strain of the cold-tolerant pathogens Listeria monocytogenes, Aeromonas hydrophila and Yersinia enterocolitica were individually inoculated into samples of commercial pâté and incubated at 4 and 10 degrees C. The organisms were periodically estimated by presumptive counts, then values for the lag and generation times were calculated. Both strains of L. monocytogenes grew at both temperatures. The food strain of A. hydrophila grew only at 10 degrees C, and the type strain did not grow at either temperature. Similarly, the type strain of Y. enterocolitica did not grow at either temperature, whereas the food strain grew at both 4 and 10 degrees C. In some cases growth of non-test organisms may have inhibited the growth of these latter two species. The measured values of lag and generation times did not, in general, correlate well with those predicted by response surface models, taken from the literature and produced in this laboratory. It may be that the pâté contained an inhibitor that affected the growth of the organisms. The two strains of A. hydrophila and Y. enterocolitica showed significantly different growth characteristics, reinforcing the value of using a 'cocktail' of strains in growth experiments. Differences in predicted kinetic values from the models indicate that a model for any particular strain may not reflect the growth of naturally occurring contaminants of the same species.

Aeromonas hydrophila↗
PubMed1993

Ultrasonography.

The basic principles of diagnostic ultrasonography are discussed. Normal and abnormal ultrasonographic appearances of the major organs are presented in tables and with illustrations. A description of the current status of neurosonology with illustrations of hydrocephalus is also presented.

Animals↗
PubMed1993

Presence and coincidence of Listeria spp., motile aeromonads and Yersinia enterocolitica in a cold-smoked salmon processing and packing plant.

Environmental samples and samples of partially processed fish from a cold-smoked salmon processing and packing plant, and product samples purchased from retail outlets, were examined for the presence of Listeria monocytogenes and other Listeria spp., motile aeromonads and Yersinia enterocolitica. Listeria spp. were not isolated from raw fish but were a contaminant of processed and partially processed fish. Listeria spp. were also detected in 18.8% of surfaces in contact with fish. Unlike Listeria spp., motile aeromonads were isolated from the raw fish but not from the finished product. They were more frequently isolated from environmental sources than Listeria spp. Yersinia enterocolitica was not isolated from any of the samples tested. Little evidence was found to show a coincidence of motile aeromonads and Listeria spp., since only one subset of samples showed such a link. It is concluded that contamination by Listeria spp. was from environmental sources at the processing plant at, or beyond, the slicing stage. Reducing the number of wet areas and special cleaning and sanitation considerations for a contaminated site (the freezer seal) are suggested as ways of reducing contamination of the product.

Journal Article↗
PubMed1993

Ultrasound-guided brain biopsy in dogs.

Ultrasound-guided brain biopsy of the cingulate gyrus and the head of the caudate nucleus was performed in clinically normal dogs. Dogs survived the surgery, and neurologic deficits were not detected in the 14-day postoperative period. Magnetic resonance imaging detected changes in the brain associated with biopsy in 9 dogs (90%) immediately after surgery and in 6 dogs (60%) 14 days after surgery. Fourteen days after surgery, sonography of the brain, performed through the skin overlying the burr hole, detected changes associated with biopsy in 9 dogs (90%). Histopathologic changes evident in the brain 14 days after surgery consisted of focal malacia and hemorrhage with associated subacute encephalomeningitis. Postmortem examination indicated that the biopsy specimen was accurately obtained from the desired site in 9 dogs (90%). Tissue specimens suitable for histologic examination were obtained from 10 dogs (100%). Accuracy and low morbidity of ultrasound-guided biopsy indicate that this may be a useful technique for diagnosis of focal brain disease in dogs.

Animals↗
PubMed1992

Incidence and coincidence of Listeria spp., motile aeromonads and Yersinia enterocolitica on ready-to-eat fleshfoods.

A survey for the presence of Listeria spp., Yersinia enterocolitica and motile aeromonads in 203 samples of ready-to-eat fleshfoods purchased from retail outlets was conducted. Overall, 39.4%, 3.4% and 23.2% of samples were positive for the presence of Listeria spp., Y. enterocolitica and motile aeromonads respectively. Two factors have been identified as contributing to contamination of fleshfoods by these cold-tolerant bacteria. These are (i) the method of sale; delicatessen-bought foods were notably more contaminated than similar products bought pre-packaged, and (ii) the method of preservation. For motile aeromonads fermented foods were the least contaminated, whereas smoked and cooked products had similar incidence rates. For L. monocytogenes, significantly more (41.9%) smoked products were contaminated than fleshfoods preserved by other methods. For Y. enterocolitica, only cooked products were contaminated. In the case of cooked fleshfoods it must be assumed that most contamination occurs post-cooking and that contamination rates are increased by poor food handling procedures. Of the three possible pairwise combinations of these organisms, the coincidence of Y. enterocolitica and motile aeromonads was the only one that differed significantly from a random distribution (P less than 0.001), indicating that fleshfoods contaminated with Y. enterocolitica are probably also contaminated by motile aeromonads.

Aeromonas↗
PubMed1992

Variation in growth kinetics and phenotype of Aeromonas spp. from clinical, meat processing and fleshfood sources.

Sixty-four strains of motile aeromonads (A. hydrophila, A. sobria and A. caviae), isolated from clinical meat processing and ready-to-eat fleshfood sources, and the A. hydrophila type strain were tested with respect to their growth kinetics at 4 degrees C and 37 degrees C, and the reported indicators of pathogenicity: autoagglutination and haemolysis (tested using a CAMP reaction). Between the species, A. caviae grew the fastest at 37 degrees C and had the highest percentage of strains not able to grow at 4 degrees C (after 200 h incubation). Within the species, food-derived strains of A. hydrophila were better adapted to growth at lower temperatures than those from clinical or meat processing sources. Clinical strains of A. hydrophila autoagglutinated more frequently than those from other sources, but not differences in CAMP reactions were noted. Aeromonas caviae and A. sobria isolates appeared to be homogeneous with respect to growth kinetics at the temperatures tested. A comparison of the growth kinetics of the A. hydrophila type strain and a food-derived A. hydrophila strain clearly reflected the latter's enhanced ability to grow at low temperatures.

Aeromonas↗
PubMed1992

Arg-Gly-Asp (RGD) peptides alter hepatic killing of Candida albicans in the isolated perfused mouse liver model.

The isolated perfused mouse liver model was used to study the effect of Arg-Gly-Asp (RGD)-containing peptides on hepatic trapping and killing of Candida albicans. After extensive washing, 10(6) C. albicans CFU were infused into mouse livers. At the time of recovery, 63% +/- 2% (mean +/- standard error of the mean) of the infused C. albicans CFU were recovered from the liver and 14% +/- 1% were recovered from the effluent for a total recovery of 77% +/- 2%. This indicates that 86% +/- 9% of the original inoculum was trapped by the liver and that 23% +/- 2% was killed within the liver. Prior to their infusion into livers, 10(7) CFU of C. albicans were incubated at 37 degrees C for 30 min in the presence of various RGD peptides (0.1 mg/ml). Repeatedly, more than 90% of the infused RGD-treated C. albicans was trapped by the perfused liver. In comparison with the 23% killing rate observed in control livers, perfused livers killed approximately 40 to 50% of the infused C. albicans treated either with fibronectin, PepTite 2000, RGD, or RGDS. Hepatic killing of C. albicans treated with PepTite 2000 or fibronectin was dose dependent. Treatment of C. albicans with GRGDTP, GRGDSP, GRADSP, or GRGESP did not alter the ability of the perfused liver to kill C. albicans, suggesting that a degree of specificity for RGD peptides is associated with an increased ability of liver to kill RGD-treated C. albicans. Together, the data suggest that RGD peptides bind to a receptor on the surface of C. albicans, thereby increasing hepatic, and presumably Kupffer cell, killing of C. albicans. Natural or synthetic RGD peptides may serve as opsonins promoting C. albicans killing by Kupffer cells.

Amino Acid Sequence↗
PubMed1992

Effect of lectins on hepatic clearance and killing of Candida albicans by the isolated perfused mouse liver.

The isolated perfused mouse liver model was used to study the effects of various lectins on hepatic trapping and killing of Candida albicans. After mouse livers were washed with 20 to 30 ml of perfusion buffer, 10(6) C. albicans CFU were infused into the livers. At the time of recovery, 63% +/- 2% (mean +/- standard error of the mean) of the infused C. albicans CFU were recovered from the liver and 14% +/- 1% were recovered from the effluent for a total recovery of 77% +/- 2%. This indicated that 86% +/- 9% of the original inoculum was trapped by the liver and that 23% +/- 2% was killed within the liver. When included in both preperfusion and postperfusion buffers (0.2 mg of lectin per ml), Ulex europeaus lectin (binding specificity for fucose) decreased hepatic trapping of C. albicans by 37% and eluted trapped C. albicans from the liver only when included in postperfusion buffer. By comparison, treatment of C. albicans with U. europeaus lectin before infusion had no effect on the trapping or killing of yeast cells. When Lens culinaris lectin (binding specificity for mannose) was included in the perfusion buffers, hepatic killing of C. albicans increased by 16% with no significant effect on hepatic killing when yeast cells were treated with L. culinaris lectin before infusion. Forty to 55% of the infused C. albicans were killed when concanavalin A (binding specificities for mannose and glucose), Glycine max (binding specificity for N-acetylgalactosamine), or Arachis hypogea (binding specificity for galactose) lectin was included in the perfusion buffer or when yeast cells were treated with these lectins before their infusion. When C. albicans was treated with concanavalin A at a concentration of less than 0.02 mg/ml, hepatic killing of yeast cells was not significantly increased. The data suggest that a fucose-containing receptor on the surface of either sinusoidal endothelial cells or Kupffer cells is involved in the trapping of C. albicans by the perfused mouse liver. Moreover, lectins with binding specificities for mannose, N-acetylgalactosamine, and galactose increased hepatic killing of C. albicans.

Animals↗
PubMed1990

Improved synthetic routes to the novel thromboxane receptor antagonist ICI 192605: activity of synthetic 1,3-dioxane intermediates.

A study of the synthetic routes to the thromboxane receptor antagonist ICI 192605 4(Z)-6-(2-o-chlorophenyl-4-o-hydroxyphenyl-1,3-dioxan-cis-5-yl) hexenoic acid is described which led to an improvement in overall synthetic yield from 20 to 55%. Invitro thromboxane receptor antagonist data are reported for the novel 1,3-dioxane synthetic intermediates. These data indicated that shortening of the side chain in an appropriately substituted 2,2-dimethyl-1,3-dioxane (e.g. ICI 180080) from a heptenoic acid, to a hexenoic acid, had little effect on thromboxane receptor antagonist potency (pA2 = 7.5 rabbit thoracic aorta for the heptenoic acid ICI 180080 and pA2 = 6.9 for the corresponding hexenoic acid. Human platelet aggregation pA2 values were 6.7 and 7.0, respectively).

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1988

Enumeration of thermophilic heterotrophs in geothermally heated soils from mount erebus, ross island, antarctica.

Soil samples with temperatures up to 64 degrees C were collected from Mount Erebus, an active volcano located on Ross Island, Antarctica. Acridine orange direct counts and most probable number counts of soil samples stored at 4 degrees C for 2 months showed a wide variation in the number of thermophilic microorganisms in different soils. Organisms similar to Clostridium thermohydrosulfuricum, Bacillus schlegelii, and Bacillus acidocaldarius, as well as neutrophilic Bacillus strains, were isolated.

Journal Article↗
PubMed1987

The in vivo biodegradation of nylon 6 utilized in a particular IUD.

The particular IUD of this study was composed of a plastic shield and a nylon 6 coated filament tail string. This IUD was unique, in the fact that its tail string was the only one (and has been to date) that consisted of a coated multifilament arrangement. Studies on the tail string have revealed bacteria and debris existing between the outer filaments that are underneath the coating. Other studies have reported that removed devices were found to exhibit an unusually high incidence of breaks in the tail string coating. Studies at the University of Lowell also found that upon examination of devices that had been in vivo for periods of two years or longer, 67% of these devices examined had breaks in the coating of the tail string. Investigations have determined that the design of the tail string was serving as an avenue of transport for the bacteria to bypass the protective cervical mucus barrier and enter the sterile uterine cavity through the breaks in the tail string coating. This mechanism has been suggested to account for the higher frequency of uterine infections associated with this device. Research at the University of Lowell was undertaken to study the degradation of the nylon 6 coating and to determine the in vivo degradation mechanism. The biochemistry of the fluids present in the reproductive tract were carefully documented and the more aggressive ones selected for in vitro trials. The results of the study revealed that the in vivo physical breakdown of the coating may depend upon a series of mechanisms and variables.

Biodegradation, Environmental↗