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PubMed1981

Field evaluation of enzyme-linked immunosorbent assay for detection of antibody to African swine fever virus.

The enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to African swine fever virus was evaluated under field conditions in the Dominican Republic. A total of 3,402 swine serums were tested by ELISA. All ELISA-positive serums (n = 224) and 426 of 2,760 ELISA-negative serums were retested by indirect immunofluorescence (IIF). There were no antibodies to ASF virus detected by IIF in ELISA-negative serums. By IIF, antibodies were detected in only a small portion of the ELISA-positive serums. The specificity and sensitivity of ELISA and IIF were investigated and discussed. It appears that poor quality serums had an effect in ELISA results. Detection of immunoglobulin (Ig) G and IgM classes of antibodies in the ELISA and IIF-positive serums were also performed and related to longevity of African swine fever virus infection. The ELISA is recommended as an efficient method in testing large number of serums; positive results are to be retested by IIF.

African Swine Fever↗
PubMed1980

Western hemisphere isolates of African swine fever virus: asymptomatic carriers and resistance to challenge inoculation.

Convalescent clinically normal pigs were tested for the persistence of African swine fever (ASF) infection. One group of pigs was examined 135 days after inoculation with a Brazilian isolate and a 2nd group was examined 110 days after inoculation with a Dominican Republic isolate. Susceptible pigs exposed by contact to these groups remained clinically normal. These contact pigs plus 2 more pigs added to each group developed ASF after being fed and inoculated with tissues collected from recovered pigs. African swine fever virus was not isolated in swine buffy coat cultures inoculated with supernatant fluid from the collected tissues. The remaining convalescent Brazilian and Dominican Republic ASF pigs were challenge inoculated with homologous virus and then with Lisbon 60 ASF virus. Pigs in both groups remained clinically normal after homologous virus challenge inoculation. Pigs in the Brazilian group remained clinically normal after inoculation of the lisbon 60 ASF viral isolate. Of 5 pigs in the Dominican Republic group, 3 developed a transient viremia after inoculation of the Lisbon 60 ASF viral isolate.

African Swine Fever↗
PubMed1988

Difference in growth behavior of human, swine, equine, and avian influenza viruses at a high temperature.

Growth characteristics of a wide range of influenza A viruses from different mammals and bird species were examined in an established line of canine kidney (MDCK) cells at an ordinary (37 degrees C) and a high temperature (42 degrees C). Although all viruses employed in the present study possessed a capability of replicating at 37 degrees C, virus growth at 42 degrees C showed considerable variation and reflected differences in the natural hosts of the isolates. All reference strains and isolates from bird species grew well in the MDCK cells maintained at 42 degrees C, but human viruses did not, showing an asymmetrical growth behavior. In contrast to this, growth of swine and equine viruses showed growth characteristics intermediate between human and avian viruses. Of the two swine viruses examined, replication of one strain occurred equally well at both temperatures and another failed to grow at 42 degrees C. Similarly, two of the three equine viruses tested belonging to H3N8 antigenic subtypes grew at 42 degrees C. However, the results obtained from comparison of plaque sizes and growth curves indicated that the replication of the above swine and equine viruses was restricted under a stringent temperature when compared to avian viruses. The detailed analysis of cloned viruses revealed that some of the swine and equine viruses contained two variants which are readily distinguished by growth behavior at 42 degrees C. Genome analysis of parental and virus clones by oligonucleotide mapping and migration profiles of RNA segments did not detect any differences among the above variants exhibiting the asymmetrical growth characteristics at 42 degrees C.

Animals↗
PubMed1994

Magnesium deficiency prolongs myocardial stunning in an open-chest swine model.

The effect of magnesium deficiency on postischemic myocardial dysfunction (myocardial stunning) in an open-chest swine model was studied. Twelve swine were assigned either to low magnesium diet or control diet. Myocardial stunning was assessed by measuring regional wall thickening by epicardial Doppler before and after brief occlusion (8 min) of the left anterior descending coronary artery. Serum magnesium levels decreased significantly in the experimental group only. Glutathione levels were 42.6% lower in the magnesium deficient swine than in controls. Stunning time was significantly prolonged from 32.8 +/- 3.1 min in the control group to 43.8 +/- 4.6 min in the hypomagnesemic swine. In conclusion, magnesium deficiency is associated with prolonged recovery from myocardial stunning.

Animal Feed↗
PubMed2004

Application of group specific amplified rDNA restriction analysis to characterize swine fecal and manure storage pit samples.

Group specific amplified ribosomal-DNA restriction analysis was evaluated as a method to rapidly assess microbial community structure in swine fecal and manure storage pit samples. PCR primer sequences were evaluated for their specificity to ribosomal DNA from selected bacterial groups by optimizing annealing temperatures and determining specificity using a set of primer target and non-target organisms. A number of primer sets were identified targeting the following groups: Bacteroides-Prevotella, clostridial clusters I and II, clostridial clusters IX and XI, clostridial clusters XIVa and XIVb, Lactobacillus, Desulfovibrionaceae and Streptococcus-Lactococcus, as well as an universal primer set to represent total populations. Each bacterial group was digested with at least three restriction enzymes. We applied the group specific amplified ribosomal-DNA restriction analysis to swine fecal and manure storage pit samples obtained on two separate occasions. Fecal and manure storage pit samples obtained on the same day were more similar to each other than to any other samples. Results were consistent with 16S ribosomal DNA sequencing data from bacterial isolates and clones obtained from swine feces and manure storage pit. The group specific amplified ribosomal-DNA restriction analysis technique was able to rapid detect gross bacterial community differences among swine fecal and manure storage pit samples and determine groups of interest for more detailed examination.

Journal Article↗
PubMed2004

Catheter-based impedance measurements in the right atrium for continuously monitoring hematocrit and estimating blood viscosity changes; an in vivo feasibility study in swine.

Hematocrit is the most important determinant of whole blood viscosity and it affects thrombosis. As hematocrit can be measured accurately in vitro by using an electrical impedance technique, aim of the present study is to investigate the diagnostic potential of using this technique in vivo to continuously monitor hematocrit. Characteristics of a special catheter for in vivo measurement of electrical resistivity in blood in the right atrium are described. In five anesthetized swine hematocrit is monitored continuously with this catheter while different levels of hemoconcentration are induced. In addition, blood viscosity is increased by inducing 'acute phase' reaction the day before surgery, resulting in variable degree of elevated fibrinogen levels in the five swine. Good reproducibility of the resistivity measurements (S.D < 0.01) and excellent correlation between resistivity data in vivo and hematocrit levels in each swine are found (r2 = 0.95-0.99). Furthermore, stepwise regression analysis of data from all swine shows a highly significant contribution also of other important parameters of blood viscosity, such as fibrinogen, total protein and temperature (cumulative r2 = 0.97). Determining hematocrit continuously in vivo by electrical resistivity measurements with a catheter in the right atrium is feasible and these measurements correlate significantly also with other important parameters of blood viscosity.

Animals↗
PubMed1980

Growth of Sinclair swine melanoma in the hamster cheek pouch.

Specimens from seven Sinclair swine melanomas were transplanted to the cheek pouches of Syrian Golden hamsters. The specimens were taken from young swine and were derived from raised tumors that either were present at birth or developed after birth from flat melanocytic lesions as well as from apparently normal skin. All seven specimens grew in the hamster cheek pouch. One lesion, derived from a 3-day-old piglet, exhibited the most aggressive growth in the hamster and was successfully transferred to other hamster cheek pouches. These results confirm the malignancy of Sinclair swine melanoma and indicate that tumors of neonatal swine contain more malignant cells than those of older animals.

Animals↗
PubMed2004

Immunohistochemistry for the detection of swine hepatitis E virus in the liver.

Swine hepatitis E virus (HEV) antigen was detected immunohistochemically in formalin-fixed, paraffin-embedded hepatic tissue from 30 naturally infected pigs. Thirty pigs from 30 different herds were selected on the basis of positive results for reverse transcription-polymerase chain reaction. Positive cells typically exhibited a red reaction product in the cytoplasm without any observable background staining. Swine HEV antigen was consistently detected in liver from all 30 pigs tested. A strong immunohistochemical signal was seen within a variable number of hepatocytes in multifocal lobules. The signal involved the majority of hepatocytes diffusely or was confined to foci of liver cells. Positive immunohistochemical signals were also detected in small and large intestine, lymph node, tonsil, spleen, and kidney. The immunohistochemistry technique developed in this study proved useful for the detection of swine HEV in formalin-fixed, paraffin-embedded tissues taken from naturally infected pigs and may be a valuable tool in studying the pathogenesis of swine HEV infection.

Animals↗
PubMed1997

Multiplane Transesophageal and Intracardiac Echocardiography in Large Swine: Imaging Technique, Normal Values, and Research Applications.

Transthoracic echocardiographic imaging has been difficult to attain in the swine model. This study: (1) compares multiplane transesophageal echocardiography (TEE) with single plane TEE and intracardiac catheter echocardiography (ICE) for imaging of the swine cardiovascular system; and (2) defines normal values using these techniques in a closed chest large swine model (n = 24, body weight 50-114 kg). Multiplane TEE increased success rate over the single plane (the variable plane array only at 0 degrees ) TEE (P < 0.01) for imaging the left ventricular (LV) long-axis view (100% vs 50%), LV outflow tract (100% vs 33%), right atrium and its appendage (79% vs 33%), ascending aorta (100% vs 58%), and aortic arch (100% vs 17%). TEE-derived normal values at end-diastole (ED) and end-systole (ES) were: LV internal diameter (ID) = 49 +/- 3 mm (ED) and 33 +/- 4 mm (ES); LV wall thickness = 7 +/- 1 mm (ED); right ventricular (RV) ID = 24 +/- 4 mm (ED); RV wall thickness = 4 +/- 2 mm (ED); left atrial ID = 48 +/- 6 mm (ES); aortic root ID = 26 +/- 3 mm (ES); LV volume = 157 +/- 49 ml (ED) and 57 +/- 22 ml (ES). Baseline LV ejection fraction (64% +/- 6%), Doppler-derived stroke volume (86 +/- 14 ml), and cardiac index (107 ml/min per kg) were determined. Basal normal values, except for an elevated cardiac index in swine, are comparable to those reported for human adults. Multiplane TEE provided better overall cardiac imaging than did single plane TEE. ICE provided higher resolution imaging of individual cardiac chambers and structures when the ultrasound catheter was introduced into the right or left heart, but whole heart imaging was limited by ultrasound penetration at 12.5 MHz. Normal indices of chamber size and function provide a reference for the physiological significance of induced pathological states in this relevant animal model.

Journal Article↗
PubMed2006

Natural transformation-mediated transfer of erythromycin resistance in Campylobacter coli strains from turkeys and swine.

Erythromycin resistance in Campylobacter coli from meat animals is frequently encountered and could represent a substantial barrier to antibiotic treatment of human infections. Erythromycin resistance in this organism has been associated with a point mutation (A2075G) in the 23S rRNA gene. However, the mechanisms responsible for possible dissemination of erythromycin resistance in C. coli remain poorly understood. In this study, we investigated transformation-mediated acquisition of erythromycin resistance by genotypically diverse C. coli strains from turkeys and swine, with total genomic DNA from erythromycin-resistant C. coli of either turkey or swine origin used as a donor. Overall, transformation to erythromycin resistance was significantly more frequent in C. coli strains from turkeys than in swine-derived strains (P < 0.01). The frequency of transformation to erythromycin resistance was 10(-5) to 10(-6) for turkey-derived strains but 10(-7) or less for C. coli from swine. Transformants harbored the point mutation A2075G in the 23S rRNA gene, as did the erythromycin-resistant strains used as DNA donors. Erythromycin resistance was stable in transformants following serial transfers in the absence of the antibiotic, and most transformants had high MICs (>256 microg/ml), as did the C. coli donor strains. In contrast to the results obtained with transformation, spontaneous mutants had relatively low erythromycin MICs (32 to 64 microg/ml) and lacked the A2075G mutation in the 23S rRNA gene. These findings suggest that natural transformation has the potential to contribute to the dissemination of high-level resistance to erythromycin among C. coli strains colonizing meat animals.

Animals↗
PubMed2003

Effectiveness of oxidation-reduction potential and pH as monitoring and control parameters for nitrogen removal in swine wastewater treatment by sequencing batch reactors.

Two bench-scale sequencing batch reactors (SBRs) were operated in a fixed hydraulic retention time study to investigate the effectiveness of oxidation-reduction potential (ORP), pH and dissolved oxygen as parameters for indicating denitrification followed by nitrification in SBRs for swine wastewater treatment. The ORP and pH profiles were monitored and evaluated under different denitrification and nitrification conditions with and without a supplemental carbon source. With a low C/N ratio, and using a suitable C/N ratio adjustment control, ORP and pH could be used as monitoring and control parameters in both the anoxic and oxic phases for practical swine wastewater treatment. High-level accumulation of nitrate was observed without any C/N ratio adjustment. In this case, ORP and pH were not useful for monitoring denitrification followed by nitrification in SBRs. According to our research, with regard to N removal, it would be better to use pH as a parameter during the oxic phase and ORP as a parameter during the anoxic phase. Using a suitable adjustment of a ON ratio in the influent by adding swine slurry, a high total nitrogen removal efficiency of up to 95.5% was reached. It was found that, in this case, the use of ORP and pH as parameters for real-time control processes was possible in swine wastewater treatment.

Journal Article↗
PubMedDate not supplied

The swine flu immunization program: scientific venture or political folly?

The author of this Article, an internationally recognized coroner perhaps best known among laymen for his incisive and tenacious criticism of the Warren Commission report on the Kennedy assassination, turns his attention to the federal government's 1976--1977 Swine Flu Immunization Program. Dr. Wecht contends that although this program may have been viewed by its key proponents as having great public health importance, or perhaps even political value, its creation and continuation nevertheless were scientifically unjustified. Furthermore, he contends, the federal government failed to inform the public adequately of important facts about the program's origins and progress, and it mismanaged the program in several important respects. Among the topics he discusses are swine flu's epidemiological history (including the 1976 Fort Dix outbreak that propelled swine flu into the national consciousness); the key elements leading to the government's decision to immunize; the government's failure to reevaluate the program seriously as problems arose; the shortcomings of the federal swine flu statute; the inadequacy of the government's investigation of the deaths of three persons in Pittsburgh within a few hours after being vaccinated (a matter that was of immediate concern to the author in his role as Coroner of Allegheny County, Pennsylvania); the long-delayed termination of the program following the emergence of a possible statistical link between the immunizations and an increase in the incidence of the Guillain-Barré Syndrome; the financial and human costs of the program; and the need for calmer, more objective decision making in future situations where immunization of the general populace is being considered.

Centers for Disease Control and Prevention, U.S.↗
PubMed1994

Distribution of forebrain diffuse axonal injury following inertial closed head injury in miniature swine.

Diffuse axonal injury (DAI) is one of the most frequently encountered types of brain damage resulting from closed head injury. This study was designed to verify whether DAI could be produced in miniature swine by rapid acceleration and deceleration of the head in the coronal plane. Hanford miniature swine (16-19 kg) were anesthetized with 3% isoflurane and their heads accelerated rapidly once through a 60-105 degrees arc in the coronal plane, producing only transient post-traumatic unconsciousness without prolonged coma. All animals made a good recovery and were sacrificed between 6 h and 10 days after injury. The response of forebrain projection systems to this injury was studied using neurofilament immunohistochemistry with antisera to nonphosphorylated (SMI-32) and phosphorylated (SMI-31) epitopes common to heavy (200 kDa) and medium (160 kDa) neurofilament proteins. In 9 of 12 animals, lesions characterized by foci of SMI-32 positive axonal retraction balls were present at the white matter/gray matter junction at the crests of gyri in the dorsolateral regions of the frontal, parietal, and temporal cortices and along margins of the lateral ventricles. A high density of pyramidal neuron perikarya in layers III and V within cortical gyri associated with subcortical DAI were intensely positive for SMI-31 immunohistochemistry. These results validate the use of miniature swine in studies of axonal injury and demonstrate that axonal injury analogous to that seen in the mildest form of DAI (grade I) can be produced in these animals without producing prolonged coma.

Animals↗
PubMed1985

Survey for potential soft tick (Acari: Argasidae) vectors of African swine fever on the island of Hispaniola.

A survey of the occurrence of Ornithodoros ticks in animal burrows was conducted in Haiti and the Dominican Republic. Vacuum sampling techniques were used. Four of 8 sample sites in Haiti and 10 of 70 sample sites in the Dominican Republic were positive for O. puertoricensis Fox. Positive sample sites in Haiti were usually near swine. Sites in the Dominican Republic were in drier regions of the country and were not directly associated with previous swine locations. The determination that O. puertoricensis, a potential vector and reservoir of African swine fever (ASF), is present in this region may pose a serious problem for eradication of ASF from the island of Hispaniola.

African Swine Fever↗
PubMed1993

Tissue tropisms of porcine parvovirus in swine.

Late-term gestation swine fetuses, similar to adult animals, are able to effectively mount immune response and survive porcine parvovirus (PPV) infection. An exception to this is the Kresse strain of PPV, which causes fetal death in late-term gestation swine fetuses. In an effort to understand the basis for this profound difference in pathogenicity between Kresse strain and the prototype strain of PPV, NADL-8, studies were designed to examine potential difference in sites of replication and quantity of virus produced between Kresse and NADL-8 strains. In order to define the sites of viral replication or sites of viral sequestration in situ hybridization, using digoxigenin-labeled strand-specific oligonucleotide probes, was applied to detect the presence of either double stranded viral DNA (RF) or viral single stranded DNA in tissues of infected fetuses. The presence and the state of viral DNA was confirmed by Southern blot hybridization. Relative amounts of RF-DNA synthesis in each tissue was compared between the two virus strains. Virus replication appeared to be of comparable levels in the livers of both NADL-8 and Kresse infected swine fetuses. Differences between these strains were observed in the brain and spleen; RF-DNA was detected in the brain and spleens of Kresse infected fetuses but not in NADL-8 infected ones. These findings indicate that differences in DNA replication of the PPV strains in selective sites, as well as the quantity of virus produced, may explain the distinction in pathogenesis of these viruses.

Animals↗
PubMed1995

Inhibition of IL-2R and SLA class II expression on stimulated lymphocytes by a suppressor activity found in homogenates of African swine fever virus infected cultures.

Virus free supernatants (VFS) obtained by ultracentrifugation of homogenates of African swine fever (ASF) virus infected cultures inhibited the proliferative response and the expression in peripheral blood mononuclear cells of two activation molecules, the IL-2 receptor (IL-2R) and the swine MHC class II antigens (SLA II), induced by several stimuli (lectins, PMA plus the calcium ionophore A23187 or specific antigen). This inhibition was time dependent: no effect was seen on IL-2R expression when VFS was added after 48 h, when the expression of this molecule reached its maximum. However at this time the proliferative response was still inhibited. The presence of VFS in the cultures was necessary to inhibit both the IL-2R expression and the proliferation of cells. In these conditions the addition of exogenous IL-2 to the cultures failed to restore the IL-2R expression and the proliferation shown by control stimulated cells. Furthermore, the IL-2 activity found in supernatants from cell cultures stimulated with Con A in the presence of VFS was even higher than in cultures stimulated without VFS. The inhibition observed suggests an important impairment of host immunocompetence in ASF infected swine.

African Swine Fever Virus↗
PubMed1985

Coronary artery spasm induced in miniature swine: angiographic evidence and relation to coronary atherosclerosis.

In a swine model of coronary artery spasm, the pathogenetic role of coronary atherosclerosis was examined. Following endothelial balloon denudation of the left circumflex coronary artery (LCX), male miniature swine were fed a laboratory chow diet containing 2% cholesterol. Although there was no difference in the extent of coronary vasoconstrictive response to histamine, serotonin, and ergonovine between the left anterior descending coronary artery (LAD) and the LCX before the denudation, a constrictive response was significantly augmented along the denuded portion of the LCX 1 and 3 months after the denudation. Augmented vasoconstrictive responses to phenylephrine were never evidenced. Histamine was the most potent vasoactive agent, and coronary artery spasm was provoked repeatedly by intracoronary or intravenous administration of histamine in the presence or absence of cimetidine. The spasm was provoked only in the denuded portion of the LCX, the same area which was angiographically normal before the occurrence of the spasm. Histologically, atherosclerotic changes were predominant along the denuded portion of the LCX. Topologic correlation was suggested between the site of the spasm and the site of coronary atherosclerosis. It is concluded that in this swine model of coronary artery spasm, atherosclerotic changes may be an important causative factor, in terms of an activation of multiple receptor-operated calcium channels in the coronary artery.

Animals↗
PubMed1991

The coronary artery response to implantation of a balloon-expandable flexible stent in the aspirin- and non-aspirin-treated swine model.

Intracoronary stents may potentially alleviate some of the problems associated with coronary angioplasty. Since the anatomy and physiology of swine coronary arteries closely resemble those of humans, the response to implantation of the Glanturco-Roubin, balloon-expandable, flexible stent was studied in this model. Additionally, the effect of aspirin, 1 mg/kg/day orally, on this response was evaluated. Eighteen Hanford minature swine underwent stenting of the left anterior descending coronary artery. Two died within 24 hours of stent implantation. The 16 survivors were put to death at 4 (n = 4), 11 (n = 4), 28 (n = 4), 56 (n = 3), and 180 (n = 1) days. Angiographically, reduction of stent lumen diameter of 0.1 to 1.3 mm was observed and was maximum at 11 days, with gradual improvement at subsequent time periods. Scanning electron microscopy, transmission electron microscopy, and light microscopy showed early disruption of subjacent endothelium, and adherence of platelets to exposed subendothelium and stent wires. Microthrombi were readily apparent. At 11 days, intimal thickening, made up predominantly of smooth muscle cells with abundant extracellular matrix, was observed and covered the stent wires. At 28 days, regression of intimal thickening was apparent and a confluent endothelium with flow-directed orientation was seen. At 56 and 180 days, the luminal surface was smooth; intimal thickening averaged 525 microns over the stent wires and 55 microns away from the wires. Findings in aspirin-treated animals were similar to results in those that did not receive aspirin. Thus in this swine model, stent implantation results in a time-dependent and self-limited vascular response.

Angioplasty, Balloon, Coronary↗