Biomedical subjects

D L Harris

Publications and source records attributed to D L Harris.

At least 19 recordsLinked to original sources

PubMed2006

Use of pulsed-field gel electrophoresis of conserved XbaI fragments for identification of swine Salmonella serotypes.

Swine Salmonella isolates (n=674) from various locations throughout the United States and Canada were analyzed via pulsed-field gel electrophoresis (PFGE) with XbaI. PFGE subtypes were analyzed by cluster analysis and compared to conventional serotyping results. The analysis showed a correlation of serotype to PFGE subtype. In addition, conserved fragments were identified within the restriction patterns that were unique to each serotype. PFGE using XbaI restriction provided a possible alternative method for screening and identifying swine Salmonella serotypes.

Animals↗

PubMed2006

Preservation of necrotizing hepatopancreatitis bacterium (NHPB) by freezing tissue collected from experimentally infected Litopenaeus vannamei.

Necrotizing hepatopancreatitis (NHP), a severe disease of penaeid shrimp, is caused by bacteria (NHPB) that have previously been demonstrated to reside in tubular epithelial hepatopancreatic (HP) cells of infected shrimp. There has yet to be a successful in vitro culture method to grow the intracellular organism; therefore, it must be propagated in vivo via transmission from NHPB-infected shrimp to healthy individuals. In our studies, NHPB propagation tanks containing infected shrimp were used to maintain a constant supply of organisms for experiments. In order to develop a method for storing infectious NHPB material for future challenge studies, we collected HP tissue containing NHPB by flash freezing whole, fresh HPs at -80 degrees C for up to 80 d and used it to successfully infect specific pathogen-free Litopenaeus vannamei per os in controlled experiments. HP tissue samples were collected from dead shrimp, and PCR was performed to confirm the presence of NHPB. Our results demonstrate that the infectivity of NHPB in tissue is not altered after being frozen at -80 degrees C when compared to NHPB in fresh tissue. Thus, the continual propagation of NHPB in vivo is not required to assure a source of the infectious agent.

Animals↗

PubMed2005

Variable interpretation of ultrasonograms may contribute to variation in the reported incidence of white matter damage between newborn intensive care units in New Zealand.

BACKGROUND: The incidence of cerebral white matter damage reported to the Australian and New Zealand Neonatal Network (ANZNN) varies between neonatal intensive care units (NICUs). HYPOTHESIS: Differences in the capture, storage, and interpretation of the cerebral ultrasound scans could account for some of this variation. METHODS: A total of 255 infants of birth weight <1500 g and gestation <32 weeks born between 1997 and 2002 and drawn equally from each of the six NICUs in New Zealand were randomly selected from the ANZNN database. Half had early cerebral ultrasound scans previously reported to ANZNN as normal, and half had scans reported as abnormal. The original scans were copied, anonymised, and independently read by a panel of three experts using a standardised method of reviewing and reporting. RESULTS: There was considerable variation between NICUs in methods of image capture, quality, and completeness of the scans. There was only moderate agreement between the reviewers' reports and the original reports to the ANZNN (kappa 0.45-0.51) and between the reviewers (kappa 0.54-0.64). The reviewers reported three to six times more white matter damage than had been reported to the ANZNN. CONCLUSION: Some of the reported variation in white matter damage between NICUs may be due to differences in capture and interpretation of cerebral ultrasound scans.

Brain Diseases↗

PubMed2005

SNP analysis of AMY2 and CTSL genes in Litopenaeus vannamei and Penaeus monodon shrimp.

Genetic studies in shrimp have focused on disease, with production traits such as growth left unexamined. Two shrimp species, Litopenaeus vannamei and Penaeus monodon, which represent the majority of US shrimp imports, were selected for single nucleotide polymorphism (SNP) discovery in alpha-amylase (AMY2) and cathepsin-l (CTSL), both candidate genes for growth. In L. vannamei, four SNPs were found in AMY2 and one SNP was found in CTSL. In P. monodon, one SNP was identified in CTSL. The CTSL gene was mapped to linkage group 28 of P. monodon using the female map developed with the Australian P. monodon mapping population. Association analyses for the AMY2 and CTSL genes with body weight (BW) were performed in two L. vannamei populations. While neither gene was found to be significantly associated with BW in these populations, there was a trend in one population towards higher BW for allele G of CTSL SNP C681G.

Animals↗

PubMed2005

Evaluation of a diet free of animal protein in germfree swine.

BACKGROUND: Two experiments were conducted in which germfree pigs or pigs monoassociated with Lactobacillus paracasei subspecies paracasei were fed either a traditional milk-based diet (Esbilac) or an experimental diet free of animal protein (DFAP). METHODS: Throughout the 16-day study, animals' clinical condition, total weight gain, feed conversion, and bacterial contamination were monitored. At the conclusion of the study the animals were killed, necropsied and tissues sampled for L. paracasei isolation. RESULTS: General pig disposition remained consistent between treatment groups and trials, except for two animals that developed mild diarrhoea during trial 1. All pigs remained viable during the study irrespective the diet fed or probiotic inoculation. Germfree pigs fed the Esbilac diet gained on average a total of 1034 +/- 63.0 g, and had a feed conversion ratio of 0.17 +/- 0.01 g of gain per 1 ml of diet. Germfree pigs fed the experimental diet gained on average a total of 599 +/- 151 g, and had a feed conversion ratio of 0.10 +/- 0.02 g of gain per 1 ml of diet. Monoassociated pigs fed the Esbilac diet gained on average a total of 862 +/- 70.3 g, and had a feed conversion ratio 0.14 +/- 0.01 g of gain per 1 ml of diet. Monoassociated pigs fed the experimental diet gained on average a total of 563 +/- 96.8 g, and had a feed conversion ratio of 0.09 +/- 0.02 g of gain per 1 ml of diet. Lactobacillus paracasei established extensively in pigs fed either the Esbilac or experimental diets. Lactobacillus paracasei had no effect (P >0.05) on piglet growth and did not display any interactions based on the diet fed. Measured growth parameters were statistically different (P <0.05) based on the diet fed and variance seen between trials. CONCLUSION: In conclusion, a DFAP has been developed and has been shown to be capable of sustaining life in piglets up to 16 days of age.

Animal Feed↗

PubMed2005

Dose determination for acute Salmonella infection in pigs.

Pigs were exposed to various levels of Salmonella enterica subsp. enterica serovar Typhimurium by either intranasal inoculation or by subjecting them to a contaminated environment. More than 10(3) salmonellae were required to induce acute Salmonella infection. These results indicate that intervention against acute Salmonella infection in lairage may be more readily achieved than previously thought.

Acute Disease↗

PubMed2005

Lipopolysaccharide-based enzyme-linked immunosorbent assay for experimental use in detection of antibodies to Lawsonia intracellularis in pigs.

An enzyme-linked immunosorbent assay (ELISA) for Lawsonia intracellularis was developed and compared with a whole-cell antigen-based immunofluorescence antibody test (IFAT). The antigen-containing lipopolysaccharide (LPS) was derived from Percoll gradient purified cultures of L. intracellularis by using a modification of the Westphal hot phenol procedure. The antigen was bound directly to polystyrene 96-well microtiter plates, and the assay was performed in an indirect ELISA format. Specificity and sensitivity values based on 80 known positive and 80 known negative serum samples from controlled experimental trials were 93.7% and 88.7%, respectively. Serological results from a controlled L. intracellularis challenge exposure study confirmed the high specificity and sensitivity of this assay (100% and 99.5%, respectively). Comparisons between the LPS ELISA and the IFAT in detecting anti-Lawsonia antibodies in this controlled study revealed significantly more LPS ELISA-positive pigs than IFAT-positive pigs on days 21, 28, 35, and 42 (P = 0.003, 0.030, 0.002, and 0.006, respectively). This indirect ELISA (LPS ELISA) test is an improved method of detecting antibodies in pigs soon after exposure to L. intracellularis, regardless of isolate type (vaccine or wild type) in experimental studies. The LPS ELISA may be used as a tool to support future research trials on vaccine efficacy and to further understand the immune response induced by L. intracellularis.

Animals↗

PubMed2005

Does variation in interpretation of ultrasonograms account for the variation in incidence of germinal matrix/intraventricular haemorrhage between newborn intensive care units in New Zealand?

BACKGROUND: The incidence of germinal matrix/intraventricular haemorrhage (GM/IVH) reported to the Australian and New Zealand Neonatal Network (ANZNN) varies between neonatal intensive care units (NICUs). HYPOTHESIS: Differences in the capture, storage, and interpretation of the cerebral ultrasound scans may account for some of this variation. METHODS: A total of 255 infants with birth weight <1500 g and gestation <32 weeks born between 1997 and 2002 were randomly selected from the ANZNN database, 44 from each of the six NICUs in New Zealand. Twenty two infants from each NICU had cerebral ultrasound scans previously reported to ANZNN as normal; another 22 had scans reported as abnormal. The original scans were copied using digital photography and anonymised and independently read by a panel of three experts using a standardised method of reviewing and reporting. RESULTS: There was considerable variation between NICUs in methods of image capture and quality and completeness of the scans. However, there was little variation in the reporting of scans between the reviewers and the reports to ANZNN (weighted kappa 0.75-0.91). Grade 1 GM/IVH was generally over-reported and grade 4 under-reported to the ANZNN. CONCLUSION: For all NICUs, a high level of agreement was found between the reviewers' reports and the reports to the ANZNN. Thus the variation between NICUs in the incidence of GM/IVH reported to the ANZNN is unlikely to be due to differences in capture, storage, and interpretation of the cerebral ultrasound scans. Further investigation is warranted into the reasons for the variation in incidence of GM/IVH between NICUs.

Cerebral Hemorrhage↗

PubMed2005

Field comparison of chemical attractants and traps for Caribbean fruit fly (Diptera: Tephritidae) in Florida citrus.

Field studies in citrus were conducted to compare the following as attractants for the Caribbean fruit fly, Anastrepha suspensa (Loew): torula yeast-borax; propylene glycol (10%); a two-component lure consisting of ammonium acetate and putrescine; a two-component lure consisting of ammonium bicarbonate and putrescine; and a three-component lure consisting of ammonium bicarbonate, methylamine hydrochloride, and putrescine. Various combinations of these attractants in glass McPhail, plastic McPhail-type (Multi-Lure), and sticky panel traps were investigated in two replicated studies. In one study on wild flies, the most effective and least complex trap-lure combination tested was the Multi-Lure with propylene glycol baited with ammonium acetate and putrescine. This trap-lure combination captured significantly more female and male flies than the standard glass McPhail baited with torula yeast-borax in water. All of the trap-lure combinations were female biased, with an overall average of 80.8% (SEM 1.4) flies captured being female. A second study on laboratory-reared, irradiated flies indicated no significant differences among these trap-lure combinations with respect to number of flies recaptured, although rankings based on mean number of flies recovered per trap per day supported results of the first study. The percentage of flies recaptured that were female (83.0%, SEM 0.9) was statistically the same as in the first study. Weekly percentage recovery of flies during the second study was low, possibly due to our fly release strategy. Future release/recovery studies with laboratory-reared flies would benefit from some basic research on release strategies by using different trap densities and on relating recapture rates of laboratory-reared flies (nonsterile and sterile) to capture rates of wild flies.

Animals↗

PubMed2004

The effect of a killed porcine reproductive and respiratory syndrome virus (PRRSV) vaccine treatment on virus shedding in previously PRRSV infected pigs.

Two experiments were conducted to investigate if virus shedding could be reduced following a killed porcine reproductive and respiratory syndrome virus (PRRSV) vaccination (KV) of PRRSV infected pigs. In experiment 1, PRRSV infected pigs were vaccinated with KV on days 14 and 28 following infection. Viremia and serum neutralizing (SN) antibody were compared to infected pigs with no KV. The second experiment was conducted in an identical manner. In addition to viremia and SN antibody, virus in oropharyngeal scrapings and interferon gamma (IFN-gamma) producing cells were monitored. Magnitude and duration of viremia were not different between KV vaccinated and non-vaccinated groups. No virus was detected in oropharyngeal scraping from any pig, nor was there a difference in the detection of viral RNA. In both experiments, however, increases in SN titer and number of IFN-gamma producing cells were observed. The SN titer was significantly higher in KV vaccinated groups than in non-vaccinated group on days 42 and 42-56 following infection in experiments 1 and 2, respectively. The number of IFN-gamma producing cells was slightly higher in KV vaccinated groups than in non-vaccinated group on days 42 and 63. These observations suggest that KV had no effect on virus shedding. However, previously infected pigs responded immunologically to KV, as demonstrated by increases in SN antibody titers and IFN-gamma producing cells.

Animals↗

PubMed2004

Quantifying individual fruit fly consumption with Anastrepha suspensa (Diptera: Tephritidae).

We needed a technique to compare the consumption of baits by individual Carribbean fruit fly, Anastrepha suspensa (Loew). By improving consumption and determining individual dose, we could lower pesticide concentration while retaining bait/pesticide efficacy and potentially reduce the environmental impact of fruit fly bait/pesticide eradication methods. We report here a precise dye-based technique for the quantification of consumption by individual adult A. suspensa fruit flies. Fluorescein, measured at 491 nm, and cresol red, measured at 573 nm, were efficiently extracted with 0.1 M NaOH and quantified with a spectrophotometer. The lower limit for this method with 0.1% dye concentration is 300 nl consumed by an individual fly. Dye movement to the hindgut and possible defecation occurred in approximately 4 h; maximum ingestion occurred in approximately 1 h. Maximum experimental time is limited to 4 h. Flies preferred feeding upside down compared with right side up when given a choice; consumption was equal when flies were given no choice of feeding position. Thus, maximum bait/pesticide efficacy might be achieved with an upside-down presentation. Regurgitation led to a 100% overestimation of actual consumption with the J-tube presentation of food. Our individual fly consumption technique will be useful in comparing consumption in phagostimulant studies, estimating dose in oral toxicity tests, differentiating behavioral and physiological resistance in toxicant studies, ultimately leading to improved bait/pesticide methods and reduced environmental impact of area wide fruit fly eradication programs. This technique could be applied to studies of tephritid consumption, to the consumption of other insects, and to regurgitation studies.

Animals↗

PubMed2004

Erysipelothrix rhusiopathiae: genetic characterization of midwest US isolates and live commercial vaccines using pulsed-field gel electrophoresis.

This is the first report of molecular characterization of US erysipelas field isolates and vaccine strains of Erysipelothrix rhusiopathiae by pulsed-field gel electrophoresis (PFGE). Erysipelas in pigs is mainly caused by E. rhusiopathiae serotypes 1a, 1b, and 2. In 2001, erysipelas reemerged as a clinical problem in pigs in the midwestern United States. In this work 90 erysipelas isolates (58 recent and 28 archived field isolates as well as 4 live-vaccine strains) were genetically characterized. Because of the limited availability of antiserum, 74/90 isolates (44/58 recent isolates) were serotyped. The serotype of the majority (79.6%) of the 44 recent isolates tested was determined to be 1a, 13.6% were serotype 1b, and 6.8% of recent isolates were serologically untypeable. Among all 90 isolates, 23 different PFGE patterns were identified. There were 43 isolates identified as serotype 1a with 4 genetic patterns: 38/43, 1A(I); 3/43, 1A(III); 1/43, 1B(V); and 1/43, 3B. Sixteen serotype 1b isolates had 11 unique genetic patterns: 4/16 were genotype 1B(III), 2/16 were genotype 3A(I), and 1/16 was in genotype groups 1A(V), 1A(VI), 1A(VII), 1B(I), 1B(IV), 1B(VII), 2, 4, and 5. Six genetic patterns were distinguished among the 10 serotype 2 isolates: 1A(IV) (1/10), 1A(V) (1/10), 1B(VI) (1/10), 2 (4/10), 7 (1/10), and 8 (2/8). Erysipelas vaccine strains (modified live) were similar to each other but different from current field strains, sharing 78.6% identity with the most prevalent genotype 1A(I) based on the PFGE-SmaI pattern. Compared with serotyping, PFGE genotyping is a more distinguishing technique, easy to perform and not dependent on the limited availability of antiserum.

Animals↗

PubMed2004

Acute infection of swine by various Salmonella serovars.

The objective of this study was to evaluate the ability of various serovars of Salmonella enterica subsp. enterica to infect alimentary and nonalimentary tissues of swine within 3 h of inoculation. Fourteen wild-type S. enterica serovars (4,12:imonophasic, 6,7 nonmotile, Agona, Brandenburg, Bredeney, Derby, Heidelberg, Infantis, Muenchen, Thompson, Typhimurium, Typhimurium variant Copenhagen, untypeable, and Worthington), two known virulent S. enterica serovars (Choleraesuis strain SC-38 and Typhimurium strain chi4232), and two avirulent S. enterica Choleraesuis vaccine strains (Argus and SC-54) were inoculated intranasally (approximately 5 x 10(9) cells) into swine (four animals per Salmonella isolate). Three hours after inoculation, animals were euthanized, and both alimentary tissues (tonsil, colon contents, and cecum contents) and nonalimentary tissues (mandibular lymph node, thymus, lung, liver, spleen, ileocecal lymph node, and blood) were collected for Salmonella isolation. All Salmonella serovars evaluated except Salmonella Choleraesuis SC-54 acutely infected both alimentary and nonalimentary tissues. These results indicate that Salmonella isolates commonly found in swine are capable of acutely infecting both alimentary and nonalimentary tissues in a time frame consistent with that in which animals are transported and held in lairage prior to slaughter.

Acute Disease↗

PubMed2003

Prevention.

Explore the source record for details and available documents.

Administration, Topical↗

PubMed2003

Evaluation of the 1-2 test for detecting Salmonella in swine feces.

The 1-2 Test is a rapid culture test for the detection of motile Salmonella. The aim of this study was to evaluate the 1-2 Test for its ability to detect Salmonella in swine feces following preenrichment and selective enrichment. Pooled pen fecal samples (n = 118) and pig rectal swabs (n = 51) were cultured for Salmonella by the 1-2 Test, which was compared with the standard isolation protocol currently used in our laboratory. In addition, pen fecal samples known to be free of Salmonella were spiked with various concentrations of Salmonella enterica subsp. enterica serovar Typhimurium and cultured by both methods to determine the minimum number of organisms needed to produce a positive result. When naturally contaminated pen feces and rectal swabs were used, results obtained with the standard culture method were similar to those obtained with the 1-2 Test. However, the 1-2 Test did outperform the standard culture method when the spiked feces samples were tested (chi2 = 4.00). The test kit reduced the time and materials required for the detection of Salmonella in swine feces. The results of this study indicate that the 1-2 Test is an accurate method for monitoring Salmonella in swine feces.

Animals↗

PubMed2001

High-valent intermediates of heme proteins and model compounds.

Recent computational and experimental probes of high-valent intermediates in heme proteins and model compounds reveal a rich spectrum of chemical behavior that is dependent on the nature of the proximal ligand, metal center, distal- and proximal-binding site environment, porphyrin macrocycle architecture, and consequent electronic structure. The results of such studies reveal an underlying complexity, which is simply understood once one is cognizant of the 'chameleon'-like behavior of such intermediates is determined by the high-valent intermediate environment.

Catalase↗

PubMed2001

Prevalence of concern about physical appearance in the general population.

Using information gathered in the introductory sections of the Derriford Appearance Scales (DAS24 and DAS59), the prevalence and epidemiological characteristics of concern about physical appearance have been determined for a carefully constructed sample of the general population of southwest Devon (rural and urban). In all, 2108 usable replies were received from a postal survey of a targeted population of 5400 men and women, aged 18 and over and randomly selected with constraints for age, sex and socio-economic status. The prevalence of concern about physical appearance was highest among women through to age 60 and younger men. There was no association with socio-economic status or living status. Concerns about the nose, weight and skin disorders were reported most frequently by both men and women and additionally concerns about breasts and abdomen were reported by women and premature balding by men. The mean DAS24 and DAS59 full-scale scores of 19% of male and 25% of female responders who were concerned about appearance exceeded the mean scores of preoperative patients undergoing reconstructive and cosmetic plastic surgery. Concern about appearance is widespread in the general population. More often than not, concern is about one feature only, which runs counter to the hypothesis that concern about appearance reflects a neurotic trait. The high levels of measured psychological distress and dysfunction found in a substantial minority of those in the general population who are concerned about appearance highlight the need for appropriate services.

Adolescent↗

PubMed2001

The Derriford Appearance Scale (DAS59): a new psychometric scale for the evaluation of patients with disfigurements and aesthetic problems of appearance.

The DAS59 has been designed and developed to meet the need for an objective measure of the spectrum of psychological distress and dysfunction that is characteristic of disfigurements, deformities and aesthetic problems of appearance. Content validity has been assured by basing the scale's items on a detailed autobiographical study of representative patients. Internal consistency is high (0.98) and test-retest reliabilities are good (general population: 0.75; clinical population: 0.86). Correlations with other appropriate standardised tests show good criterion validity and good construct validity. Factor analysis of 2741 data sets (general population and clinical population) identified three factors that are not feature specific and two that are (bodily and sexual features, facial features). The DAS59 thus generates a full-scale score and five factorial sub-scale scores. The DAS59 has been standardised on the clinical population across a range of patient groups and on the general population subdivided into those concerned and those not concerned about appearance. The DAS59 is highly sensitive as a measure of change following treatment with large and significant preoperative-postoperative reductions in full-scale and factorial scores of patients treated for facial features or bodily/sexual features. The DAS59 offers benefits for patient selection in both cosmetic and reconstructive plastic surgery and in the evaluation of outcome. It provides valid and reliable data for clinical audit and governance and for evaluating the merits of one treatment protocol against another.

Adult↗