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Nitric oxide inhibition causes an exaggerated pressor response in Yucatan miniature swine.

The involvement to nitric oxide (NO) in cardiovascular and renal function was evaluated in 12 anesthetized Yucatan miniature swine. The effect of NO blockade on blood pressure was measured in six additional conscious swine. In the anesthetized swine, mean arterial pressure (MAP), heart rate, glomerular filtration rate (GFR), and urinary excretion of water, sodium, and potassium were measured after systemic inhibition of NO synthesis by NG-nitro-L-arginine methyl ester (L-NAME), and were compared with values for a control period. After NO synthesis blockade, MAP increased by 63 +/- 5 mm Hg, a far greater increase than those observed in rats, dogs, domestic swine, or humans. The changes in GFR, urine flow rate (UFR), and sodium excretion (UNaV) were time-dependent. The GFR decreased to 50 +/- 6% of control values immediately after L-NAME administration, but returned to control values within 1 h. Significant increases in UFR and UNaV were observed only during the third experimental period, 40 to 60 min after drug infusion. In the conscious swine, L-NAME administration increased MAP by 24 +/- 4 mm Hg. Administration of the sympatholytic hexamethonium bromide fully reversed the increase of MAP in anesthetized and conscious swine. These findings indicate that NO has an important role in the maintenance of cardiovascular and renal function in Yucatan miniature swine. The exaggerated pressor response to NO blockade in miniature swine appears to involve the sympathetic nervous system.

Animals↗

Status of Trichinella spiralis in domestic swine and wild boar in Canada.

Evidence of the status of trichinellosis in Canada's national swine herd is provided from data acquired through national surveillance programs and from a prevalence study of Trichinella in wild boar and domestic swine. More than 500,000 swine tested at abattoirs in ongoing animal health surveys since 1980 and 2 national swine serological surveys (1985 and 1990) showed no evidence of Trichinella infection, except for 3 occurrences in a small infected zone in Nova Scotia. The prevalence study of domestic swine and wild boar was conducted for the prevalence of Trichinella after an epidemiological investigation of a 1993 outbreak of human trichinellosis in Ontario showed that the disease was linked to the consumption of wild boar meat originating from 2 farms in the province. Sera and tissues were collected from 391 wild boar and 216 domestic swine originating from 228 farms in Quebec, Ontario, Manitoba and Saskatchewan. The survey examined approximately 37% of the wild boar slaughtered in Canada in 1994. A pepsin-HCl digestion test of the tissues and an ELISA performed on the sera did not yield any positive results. These findings and the lack of human cases of Trichinella from the consumption of Canadian pork for nearly 2 decades suggest that the parasite has been rare in domestic swine and wild boar raised in Canada. Trichinella spiralis has only been found sporadically in swine in a small region within Nova Scotia.

Animal Husbandry↗

Evidence for non-adrenergic non-cholinergic contractile responses in bovine and swine trachea.

Non-adrenergic non-cholinergic (NANC) contraction of airway smooth muscle has been observed in some but not all animal species. The aim of this study was to investigate the NANC-contractile responses in bovine and swine trachea. Proximal and distal bovine and swine trachea were cut in strips and placed in 10 ml organ baths equilibrated in Krebs Henseleit (KH) solution and electrically stimulated (10 sec, 60 V, 2 ms, 4, 10 and 30 Hz). Contractile frequency response curves performed in the presence of the muscarinic antagonist, atropine (100 mM), the angiotensin converting enzyme inhibitor, captopril (1 microM) and the neutral endopeptidase inhibitor, thiorphan (1 microM), added 30 min prior to electrical field stimulation (EFS). In some tissues, incubated with atropine thiorphan and captopril, were also evaluated the effects of a pretreatment with capsaicin (10 microM) or a selective NK1 receptor antagonist, SR 14033 (100 nM) added to the baths 30 min prior to EFS. Bovine and swine proximal and distal tracheal preparations contracted in a frequency-dependent manner to EFS (4, 10 and 30 Hz). Some experiments were also performed with substance P (0.1 nM to 1 microM) in absence or in presence of SR 14033 (10 nM or 100 nM). At the maximum frequency tested (30 Hz), the contractile response elicited in bovine proximal and distal preparations was 194.5 +/- 17.1% and 229.7 +/- 24.1%, of ACh (100 microM), respectively. Similarly, the contractile response elicited by EFS (30 Hz) in swine proximal and distal preparations was 187.2 +/- 12.1% and 181.6 +/- 9.2% of ACh (100 microM), respectively. In tissues incubated with atropine, a significant decrease in smooth muscle sensitivity to EFS was observed (P < 0.05). When tissues were pretreated with captopril and thiorphan, a significant increase in the contractile response to EFS (30 Hz) was observed in all tested tissue preparations (bovine, proximal 210.1 +/- 14.4%, distal 264.3 +/- 16.2%; swine, proximal 199.3 +/- 14.9%, distal 206.3 +/- 16.2%, P < 0.05). In the presence of atropine, captopril and thiorphan a significant increase in the contractile response was observed in bovine and swine distal preparations compared with tissues incubated with atropine only (P < 0.05). These effects were antagonized by a pretreatment with a selective NK1 receptor antagonist, SR 14033. A pretreatment with capsaicin statistically (P < 0.05) enhanced EFS-induced contraction in all tested preparations respect to tissues incubated with atropine, thiorphan and captopril. Substance P induced a concentration dependent contraction of bovine and swine isolated tracheal preparations which was antagonized by a pretreatment with a selective NK1 receptor antagonist, SR 14033. No significant difference in the contractile potency (EC50) nor in maximum response (Emax) was observed to exogenously administered substance P between proximal and distal tracheal preparations. These data suggest that NANC contractile responses are present in bovine and swine trachea and are more evident in distal airways.

Animals↗

Nucleotide sequencing analysis of the swine 433-kb genomic segment located between the non-classical and classical SLA class I gene clusters.

Genome analysis of the swine leukocyte antigen ( SLA) region is needed to obtain information on the MHC genomic sequence similarities and differences between the swine and human, given the possible use of swine organs for xenotransplantation. Here, the genomic sequences of a 433-kb segment located between the non-classical and classical SLA class I gene clusters were determined and analyzed for gene organization and contents of repetitive sequences. The genomic organization and diversity of this swine non-class I gene region was compared with the orthologous region of the human leukocyte antigen ( HLA) complex. The length of the fully sequenced SLA genomic segment was 433 kb compared with 595 kb in the corresponding HLA class I region. This 162-kb difference in size between the swine and human genomic segments can be explained by indel activity, and the greater variety and density of repetitive sequences within the human MHC. Twenty-one swine genes with strong sequence similarity to the corresponding human genes were identified, with the gene order from the centromere to telomere of HCR - SPR1 - SEEK1 - CDSN - STG - DPCR1 - KIAA1885 - TFIIH - DDR - IER3 - FLOT1 - TUBB - KIAA0170 - NRM - KIAA1949 - DDX16 - FLJ13158 - MRPS18B - FB19 - ABCFI - CAT56. The human SEEK1 and DPCR1 genes are pseudogenes in swine. We conclude that the swine non-class I gene region that we have sequenced is highly conserved and therefore homologous to the corresponding region located between the HLA-C and HLA-E genes in the human.

Animals↗

Differential counts by electron microscopy of cell types in normal intimal cell masses in swine abdominal aortas.

Hyperlipidemic diet-induced atherosclerotic lesions show a predilection for locating at the site of normal collections of intimal cells in the swine abdominal aorta. This implies that preexisting intimal cell masses (ICM) evolve into early diet-induced lesions. This study characterizes in detail the distal abdominal aortic ICM of young normal swine as a basis for a better understanding of lesion development. Seventeen male Yorkshire swine were used, from neonates to 20 weeks of age. Only three of six neonates showed multilayered ICM, the remaining three showed scattered individual cells or a single layer of cells. All older swine had multilayered ICM at a predictable ventral site corresponding to Evans blue in vivo staining. The majority of cells counted by electron microscopy were smooth muscle (89 to 94%), the remaining were macrophages (1 to 8%) and poorly differentiated cells (3 to 5%). Weanling and older swine showed high proportions of contractile smooth muscle cells. Ergastoplasm-rich smooth muscle cells comprised nearly half of the neonatal population. Stainable lipids were demonstrable in 20-week-olds, but not in younger swine. No foam cells were seen, but cells containing a few droplets totaled 2%; macrophages comprised a high proportion of these. Pyknotic dead cells were rare, being found in the neonate and 20-week-old swine. Mitoses were observed in two ergastoplasm-rich smooth muscle cells in the neonate and one each in contractile smooth muscle cells of a 14- and a 20-week-old swine. Saddlebag-shaped, atypical-appearing cells were present in all age groups, involving all three cell types, and ranging from 1 to 3%. These represented either bridged nuclei and cytoplasm or more likely artefactual distortion of relatively normal cells.

Animals↗

The influence of dietary unsaturated cis and trans and saturated fatty acids on tissue lipids of swine.

A feeding trial was conducted to evaluate the effects of dietary trans unsaturated fatty acids (trans fat) and of the interplay of dietary saturated fatty acids (saturated fat), cis unsaturated fatty acids, (cis fat) and trans fat on tissue lipids, particularly those effects suggestive of angiotoxicity. Swine were fed for 10 months a diet containing 17% added fat. Seven blends of varying proportions of the 3 fat components provided sufficient sample points to permit an examination of the interplay. Parameters under study included weight gain, serum cholesterol and triglyceride concentrations, lipoprotein lipid profile, total lipid and cholesterol concentrations of liver, heart and aorta, fatty acid composition of liver and aorta lipids and hepatic fatty acid synthesis and cholesterol synthesis and oxidation. Fat blends containing disproportionately high levels of saturated or cis fat generally elicited responses consistent with results reported by others. The notable exception was the serum cholesterol concentration. Throughout the study, the swine were hypercholesterolemic. Swine fed the high saturated fat blend had serum cholesterol levels equal to those swine fed the high cis fat blend. Serum cholesterol levels in the swine fed the other fat blends were more elevated. Another apparent anomaly was the lower concentration of lipid in the aortas of swine fed the high-saturated fat diet. The impact of the trans fat was modulated by the relative proportions of saturated and cis fat in the diet. The impact of trans fat was of greater magnitude for most parameters when the fat blend was low in saturated fat. The sole parameter suggestive of trans fat-mediated angiotoxicity was the distribution of lipids in lipoprotein fractions. Swine fed diets containing trans fat had lower relative proportions of the alpha-lipoprotein lipids. Although hypercholesterolemic, the high fat diets were not overtly angiotoxic except when fed to swine that carried a specific immunogenetically-defined low density lipoprotein.

Acetyl-CoA Carboxylase↗

Exercise unmasks autonomic dysfunction in swine with a recent myocardial infarction.

OBJECTIVE: Severe congestive heart failure is associated with autonomic imbalance consisting of an increased sympathetic and decreased parasympathetic activity. In the present study, we investigated the influence of alterations in autonomic balance on cardiovascular function in 11 swine with left ventricular (LV) dysfunction produced by a 2- to 3-week-old myocardial infarction (MI). METHODS: Swine underwent permanent occlusion of the left circumflex coronary artery resulting in MI of the lateral LV wall. Autonomic activity was studied 2-3 weeks later using blockers of muscarinic (atropine), alpha-adrenergic (phentolamine) and beta-adrenergic (propranolol) receptors. RESULTS: Under resting conditions, parasympathetic and sympathetic control of the heart and coronary circulation were similar in MI and normal swine. In contrast, during exercise of MI compared to normal swine, (i) there was a more pronounced gradual inhibition of parasympathetic control of heart rate with increasing exercise intensity; (ii) circulating catecholamines increased excessively, resulting in an increased beta-adrenergic influence on heart rate, while (iii) the beta-adrenergic influence on global left ventricular contractility was decreased, reflecting a blunted left ventricular beta-adrenergic responsiveness. Furthermore, (iv) an alpha-adrenergic vasoconstrictor influence was absent in the anterior LV wall of both MI and normal swine, while (v) the beta-adrenergic vasodilator influence in the coronary circulation was not different between normal and MI swine, which, in conjunction with the elevated catecholamine levels during exercise, suggests a diminished beta-adrenergic responsiveness of coronary resistance vessels within remote non-infarcted myocardium in MI swine. CONCLUSIONS: Swine with a recent MI display autonomic dysfunction, which is characterized by a more pronounced inhibition of parasympathetic influence and an exaggerated increase in sympathetic drive during exercise, as well as reduced myocardial and coronary vascular beta-adrenergic responsiveness.

Animals↗

Portal vein oxygen supply through a liver extracorporeal device to treat acute liver failure in Swine induced by subtotal hepatectomy: preliminary data.

AIM: To determine whether the increase of oxygen supply in the portal system by a liver extracorporeal (L.E.O.NARDO) device is effective in treating swine with subtotal hepatectomy leading to acute liver failure (ALF). METHODS: Eight swine with ALF induced by 85% to 90% liver resection and 5 minutes of ischemia-reperfusion injury were randomly divided into two groups: four animals received L.E.O.NARDO treatment and four swine were not treated (control group). Blood was withdrawn from the iliac artery and reversed in the portal venous system. An extracorporeal device was interposed between the outflow and the inflow in order to monitor the hemodynamic parameters. Each treatment lasted 6 hours. Serum and liver samples were collected in both groups. The survival was assessed at 1 week. RESULTS: L.E.O.NARDO treatment yielded beneficial effects for subtotal hepatectomy-induced ALF in swine with decreased serum transaminases as compared with the untreated group. International normalized ratio recovered rapidly in the L.E.O.NARDO group, remaining significantly lower than in untreated animals. The 7-day survival of L.E.O.NARDO group swine was significantly higher than that of untreated animals, with a significant difference. Three swine in the L.E.O.NARDO group survived 1 week while none of the swine in the control group were alive at that time. CONCLUSIONS: Oxygen supply in the portal vein through the L.E.O.NARDO device is easily applicable, efficacious, and safe and may represent a novel approach for ALF in swine induced by subtotal liver resection.

Animals↗

Comparison of immune responses against foot-and-mouth disease virus induced by fusion proteins using the swine IgG heavy chain constant region or beta-galactosidase as a carrier of immunogenic epitopes.

Previously, we demonstrated that a fusion protein (Gal-FMDV) consisting of beta-galactosidase and an immunogenic peptide, amino acids (141-160)-(21-40)-(141-160), of foot-and-mouth disease virus (FMDV) VP1 protein induced protective immune responses in guinea pigs and swine. We now designed a new potential recombinant protein vaccine against FMDV in swine. The immunogenic peptide, amino acids (141-160)-(21-40)-(141-160) from the VP1 protein of serotype O FMDV, was fused to the carboxy terminus of a swine immunoglobulin G single heavy chain constant region and expressed in Escherichia coli. The expressed fusion protein (IgG-FMDV) was purified and emulsified with oil adjuvant. Vaccination twice at an interval of 3 weeks with the emulsified IgG-FMDV fusion protein induced an FMDV-specific spleen proliferative T-cell response in guinea pigs and elicited high levels of neutralizing antibody in guinea pigs and swine. All of the immunized animals were efficiently protected against FMDV challenge. There was no significant difference between IgG-FMDV and Gal-FMDV in eliciting immunity after vaccination twice in swine. However, when evaluating the efficacy of a single inoculation of the fusion proteins, we found that IgG-FMDV could elicit a protective immune response in swine, while Gal-FMDV only elicited a weak neutralizing activity and could not protect the swine against FMDV challenge. Our results suggest that the IgG-FMDV fusion protein is a promising vaccine candidate for FMD in swine.

Animals↗

Human complement regulatory proteins protect swine lungs from xenogeneic injury.

BACKGROUND: Pulmonary xenotransplantation is not possible because of hyperacute lung injury, the pathogenesis of which is unknown. This study evaluates complement-dependent pathways of pulmonary injury during heterologous perfusion of swine lungs. METHODS: Lungs from unmodified swine and swine expressing human decay-accelerating factor and human CD59 (hDAF/hCD59 swine) were perfused with either human plasma or baboon blood. Pulmonary vascular resistance and static pulmonary compliance were measured serially, and swine lung tissue were examined by light microscopy. Complement activation was assessed by serial measurements of baboon plasma C3a-desArg concentrations. RESULTS: Perfusion of unmodified swine lungs with human plasma and baboon blood resulted in hyperacute lung injury within minutes of perfusion. However, function was preserved in swine lungs expressing human decay-accelerating factor and human CD59. In both study groups, xenogeneic perfusion with baboon blood resulted in at least a sevenfold increase in plasma C3a-desArg levels suggesting transient activation of complement. CONCLUSIONS: Lungs from swine expressing human decay-accelerating factor and human CD59 were resistant to injury during perfusion with human plasma and baboon blood, indicating that complement mediated some of the features of xenogeneic acute lung injury.

Animals↗

Prevention of acute lung injury in swine: depletion of pulmonary intravascular macrophages using liposomal clodronate.

BACKGROUND: Swine contain large numbers of pulmonary intravascular macrophages (PIMs) that mediate the physiological response observed in acute lung injury (ALI). As the hyperacute dysfunction observed in pulmonary xenotransplantation is similar to endotoxin-induced ALI, PIMs may play a critical role in pulmonary xenograft dysfunction. We used liposomal clodronate to eliminate the PIM population in a model of acute swine lung injury. MATERIALS AND METHODS: Experimental swine (n = 6) received liposomal clodronate (1.25 g/10 kg) and control swine (n = 5) received saline containing liposomes before infusion of lipopolysaccharide (450 ng/kg). RESULTS: Control swine demonstrated higher peak pulmonary artery pressures (41.8 +/- 2.2 versus 16.8 +/- 1.2 mm Hg; P < 0.0001) and higher peak pulmonary vascular resistances (1405 +/- 209 versus 353 +/- 81 dynes. s. cm(-5); P = 0.0016) in response to lipopolysaccharide infusion. Clodronate treated swine also had significantly lower serum levels of tumor necrosis factor-alpha, interleukin-6, and thrombin. CONCLUSIONS: Liposomal clodronate effectively attenuates acute swine lung injury induced by endotoxin. This method of depletion of the PIM population presents a promising new treatment of swine lungs before xenotransplantation.

Acute Disease↗

PCB and chlorinated pesticide concentrations in swine and bovine adipose tissue in Sweden 1991-1997: spatial and temporal trends.

Results from the Swedish control programme regarding organochlorines in food were used to determine time trends of organochlorine concentrations in adipose tissues from swine (4-8 months old) and bovines (non-dairy, 12-36 months) slaughtered between 1991 and 1997. Moreover, possible regional differences in concentrations were studied, as well as differences in concentrations depending on sex and age of the slaughtered animals. Multiple linear regression indicated that the concentrations of PCB, p,p'-DDE, HCB and alpha-HCH decreased by 4-17% per year, suggesting that the decline in organochlorine concentrations in the Swedish environment and biota reported during the 1970s-1990s also has occurred in meat-producing animals during the 1990s. The concentrations of PCB, DDE and HCB in bovines and PCB and DDE in swine were 1.4-3.8-fold higher in the southern parts of Sweden than in the northern parts of the country, indicating a regional difference in exposure of the animals. The organochlorine concentrations were higher in bovines than in swine, and declined faster in swine than in bovines. Moreover, the concentrations of CB 153 and p,p'-DDE were similar in bovines, but in swine the average concentrations of the two compounds differed two-fold. Apart from possible species differences in metabolism of organochlorines, this may be due to differences in the age at slaughter between swine and bovines, and differences in husbandry of the animals. In the latter case, swine are generally kept inside during their whole life span, whereas bovines are kept outside grazing during the summer period. Finally, a sex-dependent difference in concentrations was indicated in swine, but not in bovines. Our study shows that a lot of information can be 'extracted' from control program results.

Abattoirs↗

Studies on copper metabolism. XIX. The kinetics of iron metabolism and erythrocyte life-span in copper-deficient swine.

Ferrokinetic studies were performed in three copper-deficient swine and the results have been compared with similar studies in 18 normal pigs. The mean value for the plasma iron turnover rate in the deficient swine was 1.76 mg./kg. day; for the red cell iron incorporation rate, 1.24 mg./kg. day; for the red cell iron turnover rate, 1.18 mg./kg. day; for the red cell life span, 13 days. Corresponding figures in the normal swine were 1.11 mg./kg. day, 1.01 mg./kg. day, 0.59 mg./kg. day and 63 days, respectively. The red cell life span was measured by the use of radioactive chromium in a total of 26 pigs. The mean erythrocyte half-life of normal cells transfused into normal pigs was 17 days. The mean half-life of erythrocytes from copperdeficient swine transfused into copper-deficient swine was 9 days. The mean half-life of red cells from control animals transfused into copper-deficient swine was 16 days while that of erythrocytes from copper-deficient swine transfused into normal pigs, was 13 days. The mean half-life of cells from iron-deficient pigs transfused into iron-deficient pigs was 19 days. It is concluded that copper deficiency anemia results from both a shortened erythrocyte survival time and limited capacity of the bone marrow to produce red cells. It is suggested that copper is an essential component of erythrocytes in swine.

Anemia↗

Swine influenza virus infections in humans.

Influenza in swine was first recognized as an epizootic disease in 1918. During that same year influenza virus in humans caused the worst pandemic on record. The virus of swine influenza was isolated in 1930. Swine influenza virus was first isolated from humans in 1974. Since then, including the cases at Fort Dix, there have been a total of nine viral isolations from humans in the United States. Serologic evidence of infections with swine influenza virus in humans has also been obtained. Evidence for transmission of swine influenza virus to humans before 1974 is minimal and circumstantial. Recent recognition of infections with swine influenza virus may be the result of better surveillance, increased numbers of susceptible humans, or increased viral infectivity for humans. Nevertheless, the apparent frequency of human infections and the declining levels of antibodies to swine influenza virus in the human population suggest that influenza viruses of swine may be a potential sources of epidemic disease for humans.

Adolescent↗

Yersinia enterocolitica isolated from throats of swine in eastern and western Canada.

Examination of the throat flora from swine in Ontario for Yersinia enterocolitica found the incidence of serotype O:3 to vary from 20% from tonsils to 50% for throat swabs and 55% for tongues. In contrast, there were no isolations of serotype O:3 from throat swabs taken from swine in the western provinces of British Columbia and Alberta. This incidence of serotype O:3 in swine correlates well with the human incidence of the same serotype which is 81% for all human isolations of Y. enterocolitica in the eastern provinces and 4% in the western provinces of Canada. The opposite relationship is true for serotype O:5,27, which was not isolated from Ontario swine but occurred with a frequency of 3% in British Columbia swine and 24% in Alberta swine. The relative incidence in humans for serotype O:5,27 is 5% of all isolations of Y. enterocolitica in Ontario, 8% in British Columba, and 26% in Alberta. Serotype O:8, the most common human serotype in the western provinces (40% of all isolations), was not isolated from swine in this survey. The majority of Y. enterocolitica cultures of biotype 4 (serotype O:3) and biotype 2 (serotype O:5,27) were positive for autoagglutination, a test which has been associated with virulence, whereas all cultures of biotype 1 were negative. The results from this study strongly suggest that swine are an important source of human infections with both serotype O:3 and O:5,27 of Y. enterocolitica. The source of human infections in western Canada with serotype O:8 remains unidentified.

Animals↗

An experimental pilot study on controlled portal vein arterialization with an extracorporeal device in the swine model of partial liver resection and ischemia.

AIM: To determine whether the physiologically oxygenated arterial blood reversed in the portal system by means of portal vein arterialization (PVA) through an extracorporeal device which we have called L.E.O2.NARDO (Liver Extracorporeal Oxygen. NARDO) is effective in treating swine with subtotal hepatectomy leading to acute liver failure (ALF). METHODS: Ten swine with ALF induced by 85-90% liver resection and five minutes of ischemia-reperfusion injury were randomly divided into two groups: five animals received PVA extracorporeal treatment and five swine were not-treated (control group). Blood was withdrawn from the iliac artery and reversed in the portal venous system. An extracorporeal device was interposed between the outflow and the inflow in order to monitoring the hemodynamic parameters. Each treatment lasted 6 hours. Serum and liver samples were collected in both groups. The survival was assessed at 1 week. RESULTS: The PVA-extracorporeal treatment yielded beneficial effects for subtotal hepatectomy-induced ALF swine with decreased serum ammonia, transaminases and total bilirubin as compared with the untreated group. INR recovered rapidly in the PVA-extracorporeal group remaining significantly lower than in untreated animals. The 7-day survival of PVA-extracorporeal group swine was significantly higher than that of untreated animals, with a statistically significant difference (p<0.05). Four swine in the PVA-extracorporeal group survived at 1 week while none of the swine in the control group were alive at that time; an average time of 144h+/-13h and 24.4h+/-5h was observed in the PVA-extracorporeal and control groups, respectively. CONCLUSIONS: Arterial blood supply in the portal system through the extracorporeal device is easily applicable, efficacious, safe and may represent a novel approach for ALF swine induced by subtotal liver resection.

Animals↗

Metabolic clearance and secretion rates of porcine growth hormone in genetically lean and obese swine.

The metabolic clearance rate (MCR) and the secretion rate (SR) of porcine growth hormone (pGH) have been examined in swine rendered genetically either lean or obese after 18 generations of selection for or against backfat thickness. At 15 weeks of age (when the muscle:fat ratio was greater than 1) the mean half-life (t1/2), MCR, and SR, for the obese, control, and lean swine were: t1/2 = 7.4, 8.9, and 9.8 min; MCR = 341, 279, and 158 ml/min; SR = 907, 802, and 520 ng/min, respectively. At 90 kg body weight (when muscle:fat ratio was less than 1, and the age was about 30 weeks) the data for obese, control, and lean swine were: t1/2 = 11.3, 12.0, and 11.7 min; MCR =305, 280, and 336 ml/min; SR= 535, 626, and 932 ng/min, respectively. The t1/2, MCR, and SR were not significantly different among the obese, control, and lean swine at either 15 weeks or 90 kg body weight. Comparing the two stages of development, the younger swine (15 weeks of age) had a shorter t1/2 (P less than .01), and secreted and cleared more pGH on a per kg body weight basis (P less than .05) than the older swine (90 kg bodyweight, about 30 weeks of age). However, the results suggest that the selection of swine for either leanness or fatness for 18 generations did not alter the MCR and SR of pGH. In addition, the differences observed between the younger and older swine suggest that GH is cleared at a more rapid rate and more GH is available per unit of mass in the younger animals.

Age Factors↗

Airborne multidrug-resistant bacteria isolated from a concentrated swine feeding operation.

The use of nontherapeutic levels of antibiotics in swine production can select for antibiotic resistance in commensal and pathogenic bacteria in swine. As a result, retail pork products, as well as surface and groundwaters contaminated with swine waste, have been shown to be sources of human exposure to antibiotic-resistant bacteria. However, it is unclear whether the air within swine operations also serves as a source of exposure to antibiotic-resistant bacterial pathogens. To investigate this issue, we sampled the air within a concentrated swine feeding operation with an all-glass impinger. Samples were analyzed using a method for the isolation of Enterococcus. A total of 137 presumptive Enterococcus isolates were identified to species level using standard biochemical tests and analyzed for resistance to erythromycin, clindamycin, virginiamycin, tetracycline, and vancomycin using the agar dilution method. Thirty-four percent of the isolates were confirmed as Enterococcus, 32% were identified as coagulase-negative staphylococci, and 33% were identified as viridans group streptococci. Regardless of bacterial species, 98% of the isolates expressed high-level resistance to at least two antibiotics commonly used in swine production. None of the isolates were resistant to vancomycin, an antibiotic that has never been approved for use in livestock in the United States. In conclusion, high-level multidrug-resistant Enterococcus, coagulase-negative staphylococci, and viridans group streptococci were detected in the air of a concentrated swine feeding operation. These findings suggest that the inhalation of air from these facilities may serve as an exposure pathway for the transfer of multidrug-resistant bacterial pathogens from swine to humans.

Air Microbiology↗