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Biomedical subjects

J W Arnold

Publications and source records attributed to J W Arnold.

At least 19 recordsLinked to original sources
PubMed2004

Multiple imaging techniques demonstrate the manipulation of surfaces to reduce bacterial contamination and corrosion.

Surface imaging techniques were combined to determine appropriate manipulation of technologically important surfaces for commercial applications. The complementarity of the microscopy methods, scanning electron microscopy, electron probe microanalysis and atomic force microscopy assessed and correlated form and function of the surface modifications. Stainless steel disks (1 cm in diameter) were laser-cut from the same sheets of stainless steel and treated by electropolishing or left untreated for controls. Each treatment was analysed separately using each technique. First, the disks were examined by visual inspection and electron probe microanalysis for surface characteristics and elemental composition, respectively. Aliquots of bacterial suspensions (saline rinses of poultry carcasses from a commercial broiler processing plant) were then diluted in broth and monitored for growth by spectrophotometry. Stainless steel disks (1 cm in diameter) were added and the cultures were grown to sufficient density to allow attachment of bacterial cells to test surfaces. Relative differences in the surface morphology shown by atomic force microscopy, including Z ranges, roughness and other measurements, corresponded by treatment with the differences in reduction of bacterial counts shown by scanning electron microscopy. A model of wet-processing conditions tested the effects of corrosive treatment of surfaces. Less bacterial attachment occurred after corrosive treatment on controls and electropolished samples. Electropolishing significantly reduced bacterial numbers and the effects of corrosive action compared to the controls. Thus, the multiple imaging techniques showed that engineered changes on stainless steel surfaces improved the resistance of the surface finish to bacterial attachment, biofilm formation, and corrosive action.

Bacteria↗
PubMed2003

Resistance of bacterial isolates from poultry products to therapeutic veterinary antibiotics.

Bacterial isolates from poultry products were tested for their susceptibility to 10 antibiotics commonly used in the therapeutic treatment of poultry. Bacteria were isolated from fresh whole broiler carcasses or from cut-up meat samples (breast with or without skin, wings, and thighs) that were either fresh or stored at 4 or 13 degrees C (temperatures relevant to poultry-processing facilities). The Biolog system was used to identify isolates, and a broth dilution method was used to determine the antibiotic resistance properties of both these isolates and complementary cultures from the American Type Culture Collection. The antibiotics to which the most resistance was noted were penicillin G, sulfadimethoxine, and erythromycin; the antibiotic to which the least resistance was noted was enrofloxacin. Individual isolates exhibited resistances to as many as six antibiotics, with the most common resistance pattern involving the resistance of gram-negative bacteria to penicillin G, sulfadimethoxine, and erythromycin. Differences in resistance patterns were noted among 18 gram-positive and 7 gram-negative bacteria, and comparisons were made between species within the same genus. The data obtained in this study provide a useful reference for the species and resistance properties of bacteria found on various raw poultry products, either fresh or stored at temperatures and for times relevant to commercial processing, storage, and distribution. The results of this study show that resistance to antibiotics used for the therapeutic treatment of poultry occurs in bacteria in the processing environment.

Animals↗
PubMed2002

Nutrient substrates used by bacterial isolates from the poultry processing environment.

In order to successfully prevent pathogens found in biofilms in poultry processing facilities from contaminating products, knowledge of the sources and properties of the bacteria from these environments is needed. Bacteria were isolated from fresh cut-up meat samples (breast with or without skin, wings, and thighs) that were not stored or were stored at 4 or 13 C (temperatures relevant to poultry processing facilities). Profiles of the nutrient substrates used by individual bacterial species were determined using Biolog microtiter plates with different substrates in 95 wells of each plate. Pure cultures of bacterial isolates were inoculated onto gram-positive (GP) or gram-negative (GN) Biolog plates, and transformation of specific substrates was determined by reduction (indicated by a purple color) of the tetrazolium violet included in each well. Of the 62 substrates common to GP and GN microtiter plates, one-third were used by 50% or more of all bacterial isolates. Similarly, approximately one-third of the substrates were used by gram-negative bacteria but not by gram-positive bacteria. One-fourth of the substrates were also only used by a single isolate in the respective gram-type category. For the remaining 33 substrates on each of the GP and GN plates, a higher percentage of substrates on GN than on GP plates were used by the respective isolates. These substrate utilization profiles of bacteria isolated from the poultry processing environment are a useful reference for selecting nutrients for the growth or control of these bacteria, especially pathogens.

Animals↗
PubMed2000

Surface finishes on stainless steel reduce bacterial attachment and early biofilm formation: scanning electron and atomic force microscopy study.

Three common finishing treatments of stainless steel that are used for equipment during poultry processing were tested for resistance to bacterial contamination. Methods were developed to measure attached bacteria and to identify factors that make surface finishes susceptible or resistant to bacterial attachment and biofilm formation. Samples of the treated surfaces (sand-blasted, sanded, and electropolished) were exposed to natural bacterial populations from chicken carcass rinses to allow growth of bacteria and development of biofilms on the surfaces. The kinetics of bacterial growth during surface exposure was followed by UV-visible spectrophotometry, and counts of bacteria and early biofilm formation were measured following scanning electron microscopy (SEM). The surface morphology of the samples was analyzed by atomic force microscopy (AFM) with samples from each of the batches of treatments used in the SEM studies. Relative differences in the surface morphology, including fractal dimensions, Z ranges, roughness, and other measurements corresponded by treatment with the differences in reduction of bacterial counts shown by SEM. The surface types varied in affinity for bacteria, and both physical and electrochemical treatments improved resistance of stainless steel to bacterial attachment. Electropolished stainless steel was the least rough surface and showed significantly fewer bacterial cells and beginning biofilm formations than the other treated surfaces. Food safety could be improved if bacterial populations could be reduced during processing by increasing the use of materials that are resistant to bacterial contamination. These findings will aid equipment manufacturers and processors in selecting materials and finishes that are most resistant to bacteria and biofilm formation.

Animals↗
PubMed2000

Comparison of poultry processing equipment surfaces for susceptibility to bacterial attachment and biofilm formation.

During processing of poultry meat products, broiler carcasses come in contact with many solid surfaces. Bacteria from the carcasses can attach to wet equipment surfaces, form biofilms, and provide a source of cross-contamination for subsequent carcasses. In this study an array of common equipment surface materials was compared for susceptibility to bacterial attachment and biofilms. To model mixed microbial populations relevant to poultry processing, samples were taken directly from the processing line and exposed to the surface materials. Whole carcasses were rinsed with phosphate-buffered saline (100 mL), and the rinse was diluted in nutrient broth. Absorbance values (412 nm) of the suspensions at varying dilutions containing test surfaces were compared hourly with controls without test surfaces. The kinetics of bacterial attachment and biofilm formation on test surfaces were determined under the influence of pH, time, and bacterial cell density, and the elemental composition of the surface materials was determined by energy-dispersive X-ray analysis. Our results showed that surfaces vary in affinity for bacterial attachment and biofilm formation. Analysis by spectrophotometry and scanning electron microscopy confirmed that attachment to stainless steel, polyethylene, and belting was not significantly different from controls. Attachment to picker-finger rubber was significantly less than attachment to stainless steel and the other surfaces. In fact, picker-finger rubber inhibits bacterial contamination. An increased understanding of bacterial attachment and biofilm formation will assist in the development of interventions to counteract these processes and, thereby, enhance plant sanitation and pathogen control.

Animals↗
PubMed1999

Utilization of substrates by bacterial communities (biofilm) as they develop on stored chicken meat samples.

Understanding and controlling the metabolic processes of microorganisms associated with chicken meat can lead to safer poultry products with a longer shelf life. The objective of the present study was threefold: 1) to determine the feasibility of using 96-well Biolog GN microtiter plates to assess substrate utilization profiles of bacterial communities (biofilm) as they develop on poultry products, 2) to identify substrates metabolized by microbial populations associated with stored chicken meat, and 3) to compare the substrate utilization profiles of biofilm communities as they develop on meat stored at 4 C (refrigeration temperature) for up to 5 d or at 13 C (a temperature common in poultry processing areas) for 2 d. The protocol used herein for preparing inocula for microplates was acceptable for the collection of optical density values (590 nm) in microplate wells as an indicator of microbial substrate utilization over time. Data from treatment of chicken meat samples using this protocol indicate that most of the 95 substrates tested were metabolized by microbial communities present as early as 1 d after storage at 4 or at 13 C. However, the rapidity (incubation time required for initial substrate utilization) and frequency (percentage of plates positive for transformation of an individual substrate) of metabolism of the substrates by the biofilm communities varied from 4 to 164 h of plate incubation and from 17 to 100% of microplates, respectively. At 13 C, polymers were the most rapidly metabolized substrate group, followed by carbohydrates, carboxylic acids, miscellaneous or amino acids, and amides or amines. Initial utilization of these substrate groups at 4 C occurred within a consistently shorter period (24 h of plate incubation). The frequency of metabolism of each individual substrate group varied only 3 to 16% between samples stored at 4 and 13 C. However, a greater difference in frequency of utilization of some individual substrates was noted. Such divergences may be useful in characterizing biofilm communities implicated in pathogenicity or affecting food quality of poultry products.

Animals↗
PubMed1997

The disintegration of superEBA cement in solutions with adjusted pH and osmolarity.

This study determined the disintegration of fast-set SuperEBA cement using ANSI/ADA Specification No. 30 (Spec #30) as well as modifications in pH, osmolarity, time before immersion, and duration of immersion that mimic the clinical, endodontic application of this material. After immersion intervals of 24 h, 1 wk, 1 m, 3 m, or 6 m, specimens were desiccated and weighed. The preimmersion and postdehydration weights were obtained to the nearest 1.0 mg and the percent weight loss from preimmersion levels was calculated. Adjusting the osmolarity to the physiologic level of 300 mOsm/kg resulted in significantly less weight loss (p < 0.05) than the control group in distilled water (no modification of Spec #30). The pH of the storage solution was found to be a significant factor in weight loss. As the acidity and the time of immersion increased, the weight loss also significantly increased with the greatest weight loss of 19.81% at pH 5.5 after 6 m storage. Immersion within 10 min of mixing was not significantly different (p > 0.05) in weight from the control of 1 h set-time. The 24 h weight loss measurements for the pHs of 5.5 and 6.4 were greater than the 1.5% allowed by Spec #30. All other 24 h measurements were less than the 1.5%.

Analysis of Variance↗
PubMed1996

Cytotoxicity in chicken alimentary secretions as measured by a derivative of the tumor necrosis factor assay.

The host immune response to enteric bacterial infections, including salmonellosis, results in inflammatory cells entering the intestine near the site of infection. These cells produce factors, such as cytokines, that are cytotoxic to bacteria-infected cells, resulting in loss of host cells. In this study, an assay was developed, based on the tumor necrosis factor (TNF) assay, that measured the cytotoxic activity in alimentary secretions from chickens during a Salmonella enteritidis (SE) infection. Secretions were collected by pilocarpine-induced evacuation from the alimentary tract and clarified by centrifugation. Activity was assessed by the cytotoxic effect of secretions on chicken embryo fibroblasts as target cells. Cytotoxic activity from SE-infected hens was measured at intervals during the first 24 h following infection and daily for the next 10 d. The level of activity varied between hens but was maximal in secretions obtained at 24 h and 10 d after SE infection. Maximal levels of cytotoxic activity in alimentary secretions from hens occurred in response to a dose of 5x10(8) cfu/mL of SE. The cytotoxicity in secretions from SE-exposed hens that were deprived of feed was greater than those from control SE-exposed hens by more than fivefold.

Animals↗
PubMed1995

Response to Salmonella enteritidis infection by the immunocompromised avian host.

To develop knowledge of the avian immune response and improve the ability of chickens to resist infection by Salmonella enteritidis (SE), the role of the different components of the immune response against SE infection was examined. Birds were given treatments with cyclophosphamide, cyclosporine A, or testosterone propionate to induce immunological deficiency, and experiments were performed to determine the effects of each on the immune response. Each treatment reduced hatch rate, survival rate, and rate of weight gain. As measured by flow cytometry, treatments with cyclophosphamide and testosterone propionate decreased the percentages of B cells to background levels and increased the percentages of CT8 cells significantly above controls. The intestinal shed rate of SE increased after treatment with testosterone propionate and cyclophosphamide, but dissemination to the spleen of infected birds was not different from controls for any treatment. The SE infection was also immunosuppressive as measured by the proliferative response to mitogenic stimulation. Maximum lymphocyte proliferation occurred 1 wk after infection in response to .5 micrograms concanavalin A per 10(6) cells. By the 2nd wk, proliferation dropped 10-fold to almost no response. Results showed that immunocompetence relied on interdependent functions of multiple components of the immune response, i.e., aspects of both humoral and cell-mediated immunity.

Animals↗
PubMed1993

Tumor necrosis factor (TNF alpha) regulates intestinal mucus production during salmonellosis.

Mucus production by goblet cells in the gastrointestinal tract following Salmonella typhimurium infection using a ligated ileal loop model in mice was investigated. Assessment of the morphology of the loop tissue after Salmonella challenge revealed generalized tissue inflammation, characterized by edema and an inflammatory cell infiltrate. Villi were shortened and blunted, and crypts contained an increased number of cells with mitotic figures. Production of TNF alpha in the loops followed Salmonella challenge and occurred at the same time as the pathological sequelae. A nearly 50% decrease in the number of goblet cells in infected tissue compared to tissue from noninfected controls was observed at these same times. The sulfation of mucins produced by the goblet cells in infected tissues was increased in the villi but was unchanged in the crypts compared to uninfected tissues. Treatment of mice with antibody to TNF alpha before Salmonella challenge abrogated tissue pathology and returned goblet cell numbers and mucin profiles to those observed in noninfected controls. Our results indicate that TNF alpha may mediate changes in goblet cell expression and mucin sulfation in response to Salmonella challenge.

Animals↗
PubMed1993

Tumor necrosis factor-alpha mediates the early pathology in Salmonella infection of the gastrointestinal tract.

Salmonella infection of the intestinal tract results in damage to the gut epithelium. While it is generally believed that bacteria and/or bacterial products account for this pathology, the role of host factors has not been explored. Using a ligated intestinal loop model, we investigated whether tumor necrosis factor-alpha (TNF-alpha) could contribute to the tissue pathology associated with Salmonella infection. Intestinal segments infected with Salmonella typhimurium had high levels of fluid secretion as early as 6 h post-bacterial infection. At this time point, low levels of TNF activity were also present in the fluid obtained from infected segments. At 20 h post-infection, high levels of TNF activity were present in fluids obtained from infected intestinal segments and was characterized as TNF-alpha by neutralization experiments using rabbit antisera to TNF-alpha. TNF-alpha production was further verified by Northern blot analysis using RNA obtained from cells eluted from the infected intestinal segments. In contrast, no TNF activity was found in fluid obtained from intestinal segments challenged with cholera toxin, which induces fluid secretion with little to no inflammatory response. Double labeling by in situ hybridization and immunocytochemistry revealed that macrophages in the lamina propria were producing the TNF-alpha mRNA. To investigate what role TNF-alpha might play in Salmonella-induced inflammation, intestinal segments were injected with recombinant mouse TNF-alpha (rTNF-alpha) or mice were pretreated with antibody to TNF-alpha or a control antibody prior to Salmonella infection. The histological profile of intestinal segments injected with rTNF-alpha appeared identical to segments infected with S. typhimurium. Further, pathology was completely eliminated in infected mice pretreated with antibody to TNF-alpha. These results document the production of TNF-alpha in the intestinal tract following S. typhimurium infection and show that the early pathology induced by Salmonella infection of the gastrointestinal tract is mediated by immune mechanisms.

Animals↗
PubMed1992

Animal model for genetic evaluation of multibreed data.

Extension of beef cattle genetic evaluation procedures to multibreed data sets is proposed as a way to allow inclusion of crossbred animals into current analyses and to provide comparisons between purebred animals of different breeds. Previous papers dealing with multibreed BLUP have proposed sire or sire-maternal grandsire models. Because current models used in the beef industry are predominantly of the reduced animal model form, models were developed for animal model and reduced animal model mixed-model evaluations that would account for fixed and random additive genetic effects, along with fixed and random nonadditive genetic effects for populations with heterogeneous means and variances.

Animals↗
PubMed1991

Estimates of genetic parameters for live animal ultrasound, actual carcass data, and growth traits in beef cattle.

Growth and carcass measurements were made on 2,411 Hereford steers slaughtered at a constant weight from a designed reference sire program involving 137 sires. A second data set consisted of ultrasound measures of backfat (USFAT) and longissimus muscle area (USREA) from 3,482 yearling Hereford cattle representing 441 sires. Restricted maximum likelihood procedures were used to estimate genetic parameters among carcass traits and live animal weight traits from these two separate data sets. Heritability estimates for the slaughter weight constant steer carcass backfat (FAT) and longissimus muscle area (REA) were .49 and .46, respectively. In addition, FAT had a negative genetic correlation with REA (-.37), weaning weight (-.28), and yearling weight (-.13) but positive with marbling (.19) and carcass weight (.36). Marbling was moderately heritable (.35) and highly correlated with total postweaning average daily gain (.54) and feedlot relative growth rate (.62). Heritability estimates for weight constant USFAT and USREA were .26 and .25, respectively. The genetic correlation between weight constant USFAT and USREA was positive (.39), indicating that in these young animals USFAT does not seem to be an indication of maturity. Mean USFAT measures and variability were small (.48 +/- .17 cm, n = 3,482). Results indicate that carcass fat on slaughter steers and ultrasound measures of backfat on young breeding animals may have different relationships with growth and muscling. These relationships need to be explored before wide scale selection based on ultrasound is implemented.

Adipose Tissue↗
PubMed1988

Inhibition of cell-cell interactions in Myxococcus xanthus by congo red.

The function of molecules associated with the cell surface may be determined by examining the phenotype of cells treated with inhibitors specific to these cell surface molecules. This strategy was used to examine the function of the major Congo red receptor of the myxobacterium Myxococcus xanthus, which has a developmental cycle that involves social interactions among cells. A class of social motility mutations (A+ S-), known as dsp, may inhibit the same subcellular component as Congo red because the phenotype of wild-type cells which had been treated with Congo red resembled in several ways the phenotype of the Dsp mutants. First, Congo red inhibited agglutination of wild-type cells, whereas Dsp cells were incapable of agglutinating, even in the absence of Congo red. Second, Congo red inhibited fruiting body formation by wild-type cells and reduced the yield of myxospores. Untreated Dsp cells were unable to form fruiting bodies and produced few myxospores. Third, Congo red reduced the rate of wild-type gliding motility to a level comparable to that of untreated Dsp cells, but did not inhibit the A motility of Dsp cells. Finally, binding studies showed that Dsp cells lacked the major Congo red receptor. Wild-type cells bound Congo red with an apparent association constant of 2.4 X 10(5) M-1, while Dsp cells bound it with an apparent association constant of 8.5 X 10(3) M-1. Binding of Congo red to wild-type cells was saturated in less than 10 min and was reversible when excess Congo red was removed. These results suggest that the Congo red receptors are controlled by the S motility system and that these receptors are involved in cell cohesion, social motility, and fruiting body formation.

Agglutination↗
PubMed1988

Cell surface properties correlated with cohesion in Myxococcus xanthus.

The gliding behavior of Myxococcus xanthus cells is controlled by two multigene systems, A and S, which encode information for adventurous and social behaviors, respectively. The S system can be genetically disrupted through mutation, such as a dsp mutation, or phenotypically disrupted by treating cells with the diazo dye Congo red (Arnold and Shimkets, J. Bacteriol. 170:5765-5770, 1988). One of the functions controlled by the S system is cell agglutination. Immediately after the induction of agglutination, wild-type cells begin to form aggregates, and within 30 min the cells are packed side-to-side in clumps containing thousands of cells. Changes in the cohesive properties of S+ cells are correlated with changes in the topology of the cell surface observed by electron microscopy. Two types of cell-associated appendages were observed on wild-type cells: thin filaments (ca. 5 nm in diameter), which have been called fimbriae or pili, at one cell pole, and thick, flaccid filaments (ca. 50 nm in diameter), referred to as fibrils, at both the sides and tips of cells. Cohesion was correlated with the secretion of the thick fibrils, which coat the cell surface and form an extracellular matrix in which the cells are interconnected. Several lines of evidence suggest that these thick fibrils are involved in cohesion. First, Dsp cells were unable to agglutinate or secrete this extracellular material. Second, wild-type cells which were treated with Congo red neither agglutinated nor secreted the extracellular fibrils. Finally, removal of the Congo red from wild-type cells restored cohesion and also restored production of the thick fibrils. Attempts to estimate the efficiency with which two cells cohered following collision suggested that under optimal conditions, one in three collisions resulted in stable contact. The collision efficiency decreased linearly as the cell density increased, suggesting a cell density-dependent regulation of cohesion. Some aspects of gliding behavior can be explained in terms of an inducer and an inhibitor of S motility.

Cell Communication↗
PubMed1978

Ten-year experience with abnormal EEGs in asymptomatic adult males.

This study reports a 10-year experience of the USAF School of Aerospace Medicine with spike waves of focal spikes on a screening electroencephalogram in aviators who did not have a history of seizure, unexplained loss of consciousness, or significant neurologic abnormality at the time of the first abnormal electroencephalogram. Only one of 20 patients went on to develop a seizure disorder 4 years after his first abnormal electroencephalogram.

Adolescent↗