Biomedical subjects

R W Griffith

Publications and source records attributed to R W Griffith.

At least 19 recordsLinked to original sources

PubMed2002

Salmonella enterica infections in market swine with and without transport and holding.

The objective of this study was to compare, by using identical sample types, the Salmonella enterica prevalences and serovar diversities between pigs necropsied on the farm and those necropsied at the abattoir after transport and holding. We necropsied 567 market weight pigs (>70 kg) from six herds. Pigs were alternately assigned to be necropsied on the farm or at the abattoir. One-half of the group was sent in clean, disinfected trailers to slaughter at a commercial abattoir. After transport (mean distance, 169 km) and 2 to 3 h of holding in antemortem pens, these pigs were necropsied. The 50 pigs remaining on the farm were necropsied the following day. The same sample types and amounts were collected for S. enterica culture at both locations. Results show a sevenfold-higher (P < 0.001) S. enterica isolation rate from pigs necropsied at the abattoir (39.9%; 114 of 286) than from those necropsied on the farm (5.3%; 15 of 281). This difference was also observed for each individual herd. All sample types showed a significantly higher prevalence when comparing abattoir to on-farm collection, respectively: lymph nodes, 9.15 versus 3.6%; cecal contents, 13.6 versus 1.8%; 1 g of fecal matter, 25.2 versus 0.7%. Recovery of additional serovars at the abattoir suggests the pigs are receiving S. enterica from extra-farm sources. This study demonstrates that rapid infection during transport, and particularly during holding, is a major reason for increased S. enterica prevalence in swine. This finding identifies the holding pen as an important S. enterica control point in the pork production chain.

Animals↗

PubMed2001

Relative distribution and conservation of genes encoding aminoglycoside-modifying enzymes in Salmonella enterica serotype typhimurium phage type DT104.

PCR was used to identify genes encoding aminoglycoside-modifying enzymes in 422 veterinary isolates of Salmonella enterica serotype Typhimurium. The identities of extra-integron genes encoding resistance to streptomycin, gentamicin, kanamycin, and apramycin were evaluated. Gentamicin resistance was conferred by the aadB gene. Kanamycin resistance was encoded by either the aphA1-Iab gene or the Kn gene. Apramycin resistance was determined by the aacC4 gene. Analysis of gene distribution did not reveal significant differences with regard to phage type, host species, or region except for the Kn gene, which was found mostly in nonclinical isolates. The data from this study indicate that pentaresistant DT104 does not acquire extra-integron genes in species- or geography-related foci, which supports the hypothesis that clonal expansion is the method of spread of this organism.

Acetyltransferases↗

PubMed2001

Antibiotic resistance in Salmonella enterica serovar Typhimurium exposed to microcin-producing Escherichia coli.

Microcin 24 is an antimicrobial peptide secreted by uropathogenic Escherichia coli. Secretion of microcin 24 provides an antibacterial defense mechanism for E. coli. In a plasmid-based system using transformed Salmonella enterica, we found that resistance to microcin 24 could be seen in concert with a multiple-antibiotic resistance phenotype. This multidrug-resistant phenotype appeared when Salmonella was exposed to an E. coli strain expressing microcin 24. Therefore, it appears that multidrug-resistant Salmonella can arise as a result of an insult from other pathogenic bacteria.

Anti-Bacterial Agents↗

PubMed2000

Haemophilus somnus-induced IgE in calves vaccinated with commercial monovalent H. somnus bacterins.

The ability of commercially available Haemophilus somnus bacterins to elicit an immunoglobulin E (IgE) response was examined in healthy calves using enzyme-linked immunosorbent assay (ELISA) and western blotting techniques. Thirty five calves were utilized in this study. Calves in Group 1 (n=7) did not receive any H. somnus vaccination and served as negative controls. Calves in each of Groups 2-5 (n=7 each) were vaccinated on days 0 (primary) and 14 (booster) with one of four commercially available H. somnus bacterins. Sera were harvested on days 0 and 14 and at weekly intervals for a total of 45 days. Sera were tested for the presence of IgE antibodies using a bovine IgE-specific ELISA. Low levels of H. somnus-specific IgE were detected by ELISA in all animals prior to the initiation of the study. All bacterins induced IgE levels that were significantly higher than control levels. Two bacterins elicited higher IgE levels at all time points. Sera were adsorbed against washed whole cells of either Salmonella typhimurium, P. multocida, or H. somnus or extracts of H. somnus. ELISA absorbance values were significantly decreased by adsorption with washed whole cells or extracts of H. somnus, whereas adsorption with other gram-negative bacteria only minimally decreased ELISA absorbance values. These results indicate that commercially available H. somnus bacterins can induce IgE antibody as early as 14 days post-vaccination. This IgE can be detected 45 days after the primary vaccination. Results also indicate that H. somnus-specific IgE antibodies can be found in serum of some cattle, possibly induced by existing or previous sensitization.

Adsorption↗

PubMed2000

Effects of heat stress on the antimicrobial drug resistance of Escherichia coli of the intestinal flora of swine.

The effects of heat stress on the antimicrobial drug resistance of Escherichia coli of the intestinal tract of swine were studied in animals from a farm that had not been supplementing antimicrobials in feed for the past 10 years. In one study, 10 finisher hogs were heat stressed (34 degrees C) for 24 h. Antimicrobial resistance levels after stress were significantly higher (P < 0.05) when compared with pre-stress levels for amikacin, ampicillin, cephalothin, neomycin and tetracycline from faecal samples. This high level of resistance persisted to slaughter that occurred at 10 days post-stress for most of the antimicrobials mentioned. In a second study, samples of different sections of the gastrointestinal tract were collected after heat stress and compared with control, non-stressed animals. Results indicated that E. coli which colonized the ileum and caecum had a higher level of resistance to ampicillin and tetracycline than the E. coli which colonized the colon and rectum. When animals were exposed to heat stress, resistance to ampicillin and tetracycline of E. coli in the lower digestive tract increased (P < 0.05) to a level similar to that observed in the ileum and caecum. Based on these findings, an investigation was made to test the hypothesis that (a) an increase in intestinal motility increases shedding of resistant E. coli and (b) heat stress induces a reduction in intestinal transit time in swine. For each study, two groups of three, randomly selected finisher hogs each were formed (treated and control groups). In study (a), induction of increased motility and peristalsis was obtained using an intramuscular injection of the cholinergic drug neostigmine methylsulphate. Escherichia coli isolates were obtained from the ileum, caecum, colon and rectum after animals were slaughtered. A higher level of ampicillin-resistant E. coli was found in the caecum (40%) than in other segments of the intestinal tract. In treated animals, level of resistance increased for organisms from the colon and rectum. Similar results were obtained for tetracycline resistance. In study (b), intestinal transit time was measured using chromium-EDTA as a marker. Swine were euthanized and samples were collected throughout the intestinal tract (duodenum to rectum) 8 h after administration of the marker to control and heat-stressed animals. Results indicated a reduced transit time for the stressed group. These findings corroborate the initial hypothesis that an outflow of resistant organisms moves from the upper tract (ileum and caecum) to the lower tract (colon and rectum).

Ampicillin↗

PubMed1998

Effects of cold stress on the antimicrobial drug resistance of Escherichia coli of the intestinal flora of swine.

Faecal samples were initially collected from pigs of different age groups, over periods considered to be seasonally normal and stable (baseline), and during times in which drastic drops in environmental temperature (cold stress) occurred. Baseline bacterial resistance to ampicillin and tetracycline were significantly higher (P < 0.05) in younger than in older pigs. Also, when animals were exposed to excessively cold conditions, there was a significant (P < 0.05) increase in ampicillin and tetracycline resistance in Escherichia coli for animals of all age groups. These results may indicate that factors other than feeding or use of antibiotics may play a role in establishing or maintaining the antibiotic resistance microflora of pigs, especially in those operations where animals are maintained outdoors, with minimal protection against extreme weather conditions.

Age Factors↗

PubMed1997

Adverse effects of Escherichia coli infection of turkeys were not alleviated by supplemental dietary vitamin E.

Two experiments were conducted to determine the influence of dietary vitamin E on the response of young male turkeys to Escherichia coli infection. A complete factorial arrangement of two concentrations of supplemental dietary vitamin E (12 or 300 IU/kg as dl-alpha-tocopheryl acetate) and infection or no infection of turkeys with E. coli was used in both experiments. In Experiment 1, each dietary treatment was fed to four pens of turkeys from 1 to 28 d of age. At 28 d, turkeys in two pens per dietary treatment received an injection of 3.0 x 10(7) E. coli cells into the left and right thoracic air sacs. All turkeys were necropsied 7 d after E. coli injection and the incidence and severity of lesions in air sacs, lungs, pericardium, and liver were determined. The same dietary vitamin E treatments were used in Experiment 2. Each diet was fed to eight pens of turkeys from 1 to 47 d of age. At 47 d, turkeys in four pens per dietary treatment received an injection of 3.0 x 10(7) cells of the same E. coli used in Experiment 1 into the left and right thoracic air sacs. All turkeys were necropsied as in Experiment 1 at 54 d of age. Weight gain and efficiency of feed utilization were impaired markedly by E. coli infection during the 7 d after injection. Livability also was decreased by E. coli infection in Experiment 1 but not in Experiment 2. Adverse effects of E. coli on performance and livability were not affected by dietary vitamin E concentration. Lesions observed in turkeys that received E. coli injection ranged from mild to severe, with the most severe lesions observed in air sacs. Lung lesions were observed frequently but were less severe than in air sacs. Dietary concentration of vitamin E had no effect on incidence or severity of lesions in air sacs or lungs. Overall, the results of these experiments show that adding 300 IU of vitamin E/kg of diet did not alleviate the adverse effects of E. coli infection in young turkeys.

Animals↗

PubMed1993

Cloning and sequencing of the gene encoding a 31-kilodalton antigen of Haemophilus somnus.

Immunoblots using bovine antibody against Haemophilus somnus as the primary antibody consistently identified 31-, 40- and 78-kDa proteins in Sarkosyl-insoluble extracts of H. somnus. A genomic library of H. somnus 8025 DNA was constructed in plasmid pUC19, and 45 recombinants expressed proteins which were recognized by bovine antiserum in Western blots (immunoblots). Ten of the recombinants expressing a 31-kDa protein caused the lysis of bovine erythrocytes. Restriction endonuclease mapping indicated that the hemolytic recombinants shared an approximately 1.7-kb BglII fragment. Southern blot analysis using the BglII fragment as a probe revealed homology among the recombinants and the presence of an identically sized BglII fragment in the chromosome of all H. somnus isolates tested. Sequence analysis indicated the presence of an 822-bp open reading frame within the 1.7-kb BglII fragment. Deletion of this open reading frame resulted in the loss of hemolytic activity and protein expression in recombinant Escherichia coli, suggesting the possible role of the 31-kDa protein as a hemolysin. An amino acid sequence deduced from the DNA sequence shared homology with outer membrane protein A of E. coli, Salmonella typhimurium, and Shigella dysenteriae, with P6 of Haemophilus influenzae, and with PIII of Neisseria gonorrhoeae. An amino acid analysis of the recombinant 31-kDa protein agreed with the amino acid composition deduced from the DNA sequence.

Amino Acid Sequence↗

PubMed1992

Characterization of the outer membrane proteins of Bordetella avium.

The outer membrane proteins of Bordetella avium were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Sarkosyl-insoluble outer membrane protein-enriched profiles from 50 virulent B. avium isolates, containing major 21,000- and 37,000-molecular-weight proteins (21K and 37K proteins, respectively) and at least 13 less intensely stained proteins with molecular weights ranging from 13,500 to 143,000, were very similar. The 21K, 27K, 31K, and 37K outer membrane proteins were shown to be associated noncovalently with the underlying peptidoglycan layer. It was necessary to treat cell envelopes with 2% sodium dodecyl sulfate and at temperatures in excess of 60 degrees C for 15 min to release these proteins. Exposure of proteins on the cell surface of B. avium was assessed by labeling with 125I followed by electrophoresis. As many as 13 bands were present in profiles from labeled whole cells. Of the surface-labeled bands, eight corresponded to bands in a radiolabeled outer membrane preparation. The outer membrane protein profile of B. avium was compared with profiles from other Bordetella spp., including 20 B. avium-like and 16 B. bronchiseptica strains isolated from turkeys. The outer membrane protein profile of B. avium was distinctly different from those of the other bordetella. The effect of variations in the growth medium on the expression of outer membrane proteins of B. avium was examined. Expression of 22K, 26K, 56K, and 73K proteins was decreased or eliminated by addition of 50 mM MgSO4 to the medium.

Bacterial Outer Membrane Proteins↗

PubMed1992

Complications of continuous spinal anesthesia.

The increased use of continuous spinal anesthesia (CSA) in recent years has resulted in research efforts directed at reducing the complications associated with the technique. Complications of CSA are categorized as general, the same as those associated with single-shot spinal anesthesia, and specific, those associated solely with CSA. General complications include infection, backache, hematoma, and neurological sequelae. Specific complications are all related to catheter use. The risk of developing the neurological complication of postdural puncture headache (PDPH) led to the use of microcatheters designed specifically for CSA. While the incidence of PDPH decreased with the use of microcatheters, the risk of developing the more serious complication of cauda equina syndrome increased, resulting in a Safety Alert being issued by the Food and Drug Administration.

Anesthesia, Spinal↗

PubMed1988

Regulation of gonadal steroidogenesis in Fundulus heteroclitus by recombinant salmon growth hormone and purified salmon prolactin.

The effects of recombinant salmon growth hormone (sGH) on plasma sex steroid levels and gonadal function were investigated in hypophysectomized Fundulus heteroclitus. Effects of sGH were compared to those of purified chum salmon prolactin (sPRL), Atlantic salmon gonadotropin (sGTH), and salmon pituitary extract (sPE). Treatment with sGH significantly increased plasma concentrations of testosterone in males and estradiol-17 beta in females; sPRL had similar effects on testosterone levels in males. Further, treatment with these hormones prevented the decline in gonadal weight observed after hypophysectomy in both males and females. In vivo treatment of male fish with sGH also augmented testosterone and 11-ketotestosterone production by testis tissue subsequently incubated in vitro. Direct action(s) on gonadal steroidogenesis was examined by incubating gonadal tissues from hypophysectomized fish in vitro with various hormones. sGH significantly stimulated the in vitro production of testosterone and 11-ketotestosterone by testis, and estradiol-17 beta by ovary. sPE and sGTH also stimulated gonadal steroidogenesis, whereas sPRL and bovine GH had no significant effect. By comparison, rainbow trout gonads also produced increased amounts of steroids when treated with sGH in vitro. The use of a cloned GH rules out contamination by other pituitary hormones. These results, therefore, demonstrate that recombinant salmon growth hormone possesses steroidogenic and gonadotropic activity. Purified sPRL also has steroidogenic and gonadotropic actions. However, the significance of these effects of teleost GH and PRL is not known.

Animals↗

PubMed1988

Transposon mutagenesis in Bordetella avium.

Transposon mutagenesis was used to introduce specific mutations in the chromosome of Bordetella avium. The transposon Tn5 was transferred by conjugation to B avium from Escherichia coli strain SM10 by the suicide plasmid vector pSUP1011. A defined minimal medium for growth of B avium was developed for scoring transposon-containing mutants for specific nutritional requirements. Approximately 1% of all mutants tested were auxotrophic in some form, and these organisms were grouped into 13 classes. Also, 2 classes of hemagglutination-negative mutants were isolated. Stability of Tn5 insertion was examined, and frequencies of reversion less than 10(-7) were observed, indicating stable mutations.

Bordetella↗

PubMed1988

Adherence of Bordetella avium to tracheal mucosa of turkeys: correlation with hemagglutination.

Adherence to turkey tracheal mucosa and agglutination of guinea pig erythrocytes were determined for 20 strains of Bordetella avium. Ten type-I strains, 7 type-II strains, 2 transposon-induced mutants, and 1 revertant were evaluated. All type-I strains adhered readily to tracheal mucosa and agglutinated erythrocytes, whereas no type-II strains adhered to trachea or caused hemagglutination (HA). Two mutants selected for loss of HA activity were less adherent to tracheal mucosa, compared with the parent strain. Reversion of one mutant to HA-positive status was accompanied by reconstitution of much of its adherence capacity. Results of this study provide preliminary evidence that tracheal adherence and HA of B avium are closely related.

Animals↗

PubMed1987

Freshwater or marine origin of the vertebrates?

1. Paleontological data indicate that the earliest recognizable vertebrate remains, bone fragments of Upper Cambrian and Lower Ordovician heterostracan fishes, were deposited in a marine situation. 2. Since these earliest fossils are sporadic in occurrence, from atypical marine deposits and since they only represent the full grown adult stage, the possibility of a freshwater developmental stage or estuarine habitat cannot be excluded. 3. The hagfishes, supposedly the most primitive of living vertebrates, are exclusively marine and possess an osmoregulatory strategy (monovalent ion levels nearly identical with sea-water with little capability of regulation) that is consonant with a strictly marine evolutionary history. Possibly, but less parsimoniously, this strategy and habitat could be secondarily derived. 4. The hagfish has a glomerular kidney, renal sodium reabsorption and branchial pumps for the uptake of sodium and chloride which are indicative, but not unequivocally diagnostic, of a freshwater ancestry. 5. A scenario in which the earliest vertebrate was anadromous, breeding in fresh water and migrating to the sea, is consistent with the paleontological data and with the physiology and life history of living 'primitive' fishes. It also leads to more coherent explanations for the origin of bone and for the evolution of vertebrate special senses than do alternative marine scenarios.

Animals↗

PubMed1986

Desferoxamine and iron dextran in acute Salmonella cholerae-suis infection in pigs.

Serum iron (SI)-related and hematologic changes were evaluated in a herd of weaned pigs inoculated with a strain of Salmonella cholerae-suis, causing 83% mortality within 22 days after inoculation was done. Serum iron concentrations decreased to 35% of base-line values 2 days after inoculation was done, but recovered to near base line subsequently. Total SI-binding capacity (TIBC) decreased gradually for 14 days after inoculation was done. Transferrin (TF) concentrations decreased to near half the base line throughout the postinoculation observation period. The calculated SI saturation coefficient decreased to half the base line, but recovered to or above the base-line value subsequently. Combined observations of SI, TIBC, TF, and SI saturation coefficient concentrations indicated that there was higher saturation of host iron-binding proteins and recruitment of additional iron-binding systems subsequent to 2 days after inoculation was done. Day 2 after inoculation seemed to be a critical period for host iron metabolism. Injection of supplemental iron dextran simultaneously with Salmonella infection resulted in lower mortality of iron-injected pigs (P less than 0.005). A highly significant negative correlation was observed between SI concentration and rectal temperatures after pigs were inoculated with Salmonella (r = -0.54; P less than 0.0001). Hemoglobin concentrations, mean corpuscular volume, and mean corpuscular hemoglobin were not significantly affected by Salmonella infection or iron injection concurrent with Salmonella infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1985

Iron and transferrin in acute experimental Salmonella cholerae-suis infection in pigs.

The effects of experimental Salmonella cholerae-suis inoculation with a virulent and an avirulent strain on serum iron (SI), total iron-binding capacity (TIBC), and transferrin (TF) were evaluated. Inoculation of virulent strain 38 was followed by significant (P less than 0.05) decreases of SI, TIBC, and TF. Exposure to avirulent strain 33 was followed by moderate decreases of SI, TIBC, and TF. When exposure to avirulent strain 33 was followed by challenge exposure with virulent strain 38, the SI, TIBC, and TF values remained at initial values or were higher. Negative correlation was observed between rectal temperature and SI and TIBC values, but was significant (P less than 0.0001) only 7 days after inoculation of the virulent strain 38.

Animals↗

PubMed1984

Effect of type A Pasteurella multocida fractions on bovine polymorphonuclear leukocyte functions.

The effect of various Pasteurella multocida fractions on bovine polymorphonuclear leukocyte (PMN) functions was examined in vitro by using two encapsulated strains, P-2383 and P-1062 (both are Carter capsular type A and of bovine origin). The ability of PMNs to ingest Staphylococcus aureus and iodinate protein was significantly inhibited in the presence of live cells, heat-killed whole cells, or saline-extracted capsules but not in the presence of the decapsulated heat-killed cells. None of the fractions of the two strains inhibited nitroblue tetrazolium reduction by PMNs. The saline extract did not inhibit the binding of iodine to protein by a reaction involving xanthine, xanthine oxidase, and horseradish peroxidase. The PMN inhibitory factor was further characterized as a heat-stable capsular material of greater than 300,000 molecular weight.

Animals↗

PubMed1984

Application of the peroxidase-antiperoxidase immunoassay to the identification of Salmonellae from pure culture and animal tissue.

The peroxidase-antiperoxidase immunoassay was developed by using selected Salmonella serotypes to evaluate its potential for use in diagnostic bacteriology. S. choleraesuis var, kunzendorf, S. dublin, and S. typhimurium were the test organisms. Strong specific staining with corresponding antiserum was achieved with smears of each Salmonella serotype on microscope slides from formalinized cell suspensions, live broth cultures of clinical isolates, and tissue suspensions from the livers and spleens of experimentally infected mice. In addition, S. choleraesuis var. kunzendorf was detected in Formalin-fixed and fresh frozen tissues from experimentally infected pigs. The results of this study indicate that the peroxidase-antiperoxidase assay is well-suited for the rapid identification of Salmonella from pure cultures and that the technique can be useful in research for the detection of this pathogen in histological sections.

Animals↗