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An experimental algorithm versus standard advanced cardiac life support in a swine model of out-of-hospital cardiac arrest.

STUDY OBJECTIVE: To compare an experimental algorithm with standard advanced cardiac life support in a swine model of out-of-hospital cardiac arrest. DESIGN: Randomized, controlled experimental trial. SETTING/TYPE OF PARTICIPANT: Animal laboratory using swine. INTERVENTIONS: Eighteen swine (17.8 to 23.7 kg) were sedated, intubated, anesthetized, and instrumented for monitoring of arterial and central venous pressures and ECG. Ventricular fibrillation was induced using a bipolar pacing catheter. Animals were randomized to treatment with the experimental algorithm or standard advanced cardiac life support therapy after eight minutes of untreated ventricular fibrillation. The experimental algorithm consisted of starting CPR; giving high-dose epinephrine (0.20 mg/kg), lidocaine (1.0 mg/kg), bretylium (5.0 mg/kg), and propranolol (0.5 to 1.0 mg) by peripheral IV; hyperventilating (20 to 25 breaths per minute); and delaying countershock (5 J/kg) 60 seconds after completion of drug delivery. Data were analyzed with the Student's t-test and Fisher's exact test. MEASUREMENTS AND MAIN RESULTS: Outcome variables were arterial and central venous pressures, return of spontaneous circulation, and one-hour survival. Hemodynamics were not different between groups during CPR. Return of spontaneous circulation occurred in seven of nine swine (77%) in the experimental algorithm group versus two of nine swine (22%) in the advanced cardiac life support group (P = .057). Four of nine swine (44%) in the experimental algorithm group survived to one hour versus none of the animals in the advanced cardiac life support group (P = .041). CONCLUSION: In this swine model of out-of-hospital cardiac arrest, animals treated with an experimental algorithm had a significant improvement in one-hour survival compared with those treated with advanced cardiac life support.

Algorithms↗

Mesenchymal stem cell injection induces cardiac nerve sprouting and increased tenascin expression in a Swine model of myocardial infarction.

UNLABELLED: Stem Cell Induces Cardiac Nerve Sprouting. INTRODUCTION: Mesenchymal stem cell (MSC) transplantation is a promising technique to improve cardiac function. Whether MSC can increase cardiac nerve density and contribute to the improved cardiac function is unclear. METHODS AND RESULTS: Anterior wall myocardial infarction was created in 16 swine. One month later, 6 swine were given MSC and fresh bone marrow (BM) into infarcted myocardium (MSC group). Four swine were given fresh BM only (BM group), and 6 swine were given culture media (MI-only group). The swine were sacrificed 95.8 +/- 3.5 days after MI. Six normal swine were used as control. Immunocytochemical staining was performed using antibodies against growth-associated protein 43 (GAP43), tyrosine hydroxylase (TH), and three subtypes of tenascin (R, C, and X). Five fields per slide were counted for nerve density. The results show the following. (1). There were more GAP43-positive nerves in the MSC group than in the BM, MI-only, or Control group (P < 0.0001). TH staining showed higher nerve densities in the MSC group than in the MI-only (P < 0.01) or Control group (P < 0.0001) in the atria. (2). There were more sympathetic (TH-positive) nerves in myocardium distant from infarct than in the peri-infarct area (P < 0.05). (3). Optical intensity and color analyses showed significantly higher tenascin R and tenascin C expression in the MSC and BM groups than in the MI-only or Control group (P < 0.01). CONCLUSION: MSC injected with BM into swine infarct results in overexpression of cardiac tenascin, increased the magnitude of cardiac nerve sprouting in both atria and ventricles, and increased the magnitude of atrial sympathetic hyperinnervation 2 months after injection.

Animals↗

Sodium fluxes in the erythrocytes of swine, ox, and dog.

Sodium fluxes were measured in erythrocytes from three species of mammals. Unidirectional fluxes were slowest in swine RBCs (low sodium cells), fastest in dog RBCs (high sodium cells), and between these extremes in ox cells (intermediate level of internal sodium). In addition, efflux and influx in swine cells both correlated positively with intracellular sodium concentration between 12 to 4 microeq/ml. Tracer effluxes in swine and beef cells were separated into three components: active transport, diffusion, and exchange diffusion. The last two also contributed to influx. Transport was greater in swine cells than in beef, while the leak was similar in both. Pump to leak ratios were about 21 for swine and 3 for beef, a difference that probably accounts for the higher cell sodium in the latter. Exchange diffusion was faster in beef cells than in swine resulting in a larger tracer movement in beef. The exchange mechanism was temperature-sensitive, but was not inhibited by strophanthin. The unidirectional fluxes in canine cells were inhibited by low temperature, but they were sensibly unaffected by strophanthin. When placed in magnesium Ringer's solution (inhibits exchange diffusion in beef and swine cells) dog RBCs lost more than half of their internal sodium at a rate approximating the isotope flux in plasma or normal Ringer's solution. It was, however, not possible to separate the total tracer movement into pump, leak, and exchange.

Animals↗

Effect of dietary restriction on carcass composition and adipocyte cellularity of swine with different propensities for obesity.

Experiments were conducted to determine whether dietary restriction altered body composition and adipocyte cellularity similarly in growing lean (Yorkshire) and obese (Ossabaw) swine. Yorkshire (YR) and Ossabaw (OR) swine were fed 65% of the weekly intake of ad libitum-fed Yorkshire (YA) and Ossabaw (OA) swine for 20 weeks. At 200 days of age, adipose tissue mass was 7-fold lower and muscle mass was 50% lower in YR than YA. However, adipose tissue mass of OR was only 2.6-fold less than OA. Furthermore, muscle mass did not differ between OR and OA. Adipocyte number per carcass was 6-fold higher in YA than YR. No differences in carcass adipocyte number were observed between OA and OR. Dietary restriction resulted in a reduced adipocyte size in both breeds of swine. However, adipocyte size for both dietary treatments was greater for obese than lean swine. When carcass adipocyte number was expressed per Kilogram of muscle, there were no differences among YA, OA, and OR; however, this ratio was lower in YR. These results demonstrate: 1) that alterations in nutrient partitioning as measured by accretion of these tissues are different in lean and obese swine when intake is restricted, 2) that differences in adipose tissue mass of YA and OA are due to differences in cell size, and 3) that muscle growth and adipocyte hyperplasia in swine may have a physiological relationship.

Adipose Tissue↗

Induction of malignant hyperthermia in susceptible swine by 3,4-methylenedioxymethamphetamine ("ecstasy").

BACKGROUND: 3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") can mediate acute toxic effects such as muscle rigidity, metabolic acidosis, and hyperthermia. Because of close clinical similarities, an association between MDMA intoxication and malignant hyperthermia (MH) was suggested. The aim of this study was to investigate whether MDMA is a trigger of MH in susceptible swine. METHODS: MH-nontriggering general anesthesia was performed in six MH-susceptible (MHS) and six MH-normal swine. The animals were exposed to MDMA in cumulative doses of 0.5, 1, 2, 4, 8, and 12 mg/kg. The clinical occurrence of MH was defined by achievement of two of three conditions: central venous Pco2 >/=75 mmHg, central venous pH </= 7.20, and increase of body core temperature >/= 2.0 degrees C. Once MH occurred, a standardized therapy with dantrolene, sodium bicarbonate, and hyperventilation with 100% oxygen was initialized. RESULTS: Administration of 8 mg/kg MDMA triggered MH in all MHS swine. The MH-normal swine also developed clinical signs of hypermetabolism, but even after administration of 12 mg/kg MDMA, changes were moderate compared with the MHS swine. Dantrolene therapy of MDMA-induced MH crisis in the MHS swine partially counteracted the clinical signs of MH immediately. CONCLUSIONS: MDMA induces MH in genetically susceptible swine in relevant doses. Therefore, MHS patients should avoid use of MDMA or related drugs. Patients with a personal or family history of MDMA-induced hyperthermia should be tested for a diagnosis of MH susceptibility. Dantrolene is effective in therapy of MDMA-induced porcine MH.

Animals↗

Selective aortic arch perfusion with hemoglobin-based oxygen carrier-201 for resuscitation from exsanguinating cardiac arrest in swine.

OBJECTIVE: The prospects for resuscitation after blunt traumatic cardiac arrest are dismal. Selective aortic arch perfusion (SAAP) with a hemoglobin-based oxygen carrier (HBOC-201) offers a potentially effective therapy. This study evaluated the acute cardiovascular and metabolic effects of SAAP with HBOC-201 in an exsanguination model of cardiac arrest. DESIGN: Randomized, controlled, laboratory investigation. SETTING: University research laboratory. SUBJECTS: Domestic swine, 25-39 kg. INTERVENTIONS: Partial resection of four liver lobes rapidly led to profound hemorrhagic shock and subsequent cardiac arrest at 10-13 mins. At 15 mins, swine were randomized to receive either SAAP with oxygenated lactated Ringer's (LR) solution (n = 6) or SAAP with oxygenated HBOC-201 (n = 6) at a rate of 10 mL x kg(-1) x min(-1) until return of spontaneous circulation with a mean aortic pressure of 60 mm Hg (8.0 kPa) was achieved. Epinephrine (0.005 mg/kg) was given via intra-aortic route every 30 secs as needed to promote return of spontaneous circulation beginning at 18 mins after onset of liver injury (3 mins after beginning SAAP). MEASUREMENTS AND MAIN RESULTS: Mean aortic pressure, cardiac output, total blood loss, and time of arrest were similar for both groups before SAAP therapy. In the SAAP-HBOC group, return of spontaneous circulation with a sustained mean aortic pressure of 60 mm Hg (8.0 kPa) was achieved in six of six swine at 1.9 +/- 0.3 mins of SAAP, and none of these swine required epinephrine. In the SAAP-LR group, no swine (from a total of six) achieved return of spontaneous circulation before intra-aortic epinephrine administration, and only two of six swine had brief return of spontaneous circulation with an mean aortic pressure of 60 mm Hg (8.0 kPa) after intra-aortic epinephrine that was sustained for <10 mins. One-hour survival was five of six in the SAAP-HBOC group and none of six in the SAAP-LR group (p <.05, Fisher's exact test). CONCLUSION: SAAP with oxygenated HBOC-201 rapidly restored viable cardiovascular function after exsanguinating cardiac arrest in this swine model of liver injury with profound hemorrhagic shock.

Animals↗

Clostridium botulinum type C in healthy swine in Japan.

Healthy cattle and swine bred in a district of Japan were examined for the presence of Clostridium botulinum in their liver. Liver specimens were cultivated in chopped meat-glucose medium and the cultures were examined for botulinum toxin. In cattle, none of the cultures of 100 liver specimens yielded the toxin. In swine, however, C1 or C2 toxin was demonstrated in 8 of 100 liver specimens from 36 farms. One of the five farms where the carrier-state swine were present was surveyed for about 2 years to determine whether the carrier-state was transient or resident. C. botulinum type C was found in swine livers and feces, and environmental specimens at extremely high rates during the surveillances, with 76% of specimens yielding botulinum toxin following the culture. These data suggest that it is not uncommon for healthy swine to carry C. botulinum type C in the liver and that there is a close relationship between C. botulinum carrier-state in swine and the presence of this organism in their raising environments. In 20 cattle and 20 swine suffering from parturient paresis of unknown etiology no evidence for involvement of C. botulinum type C was obtained.

Animals↗

Precision targeting of liver lesions using a novel electromagnetic navigation device in physiologic phantom and swine.

Radiofrequency ablation of primary and metastatic liver tumors is becoming a potential alternative to surgical resection. We propose a novel system that uses real-time electromagnetic position sensing of the needle tip to help with precision guidance into a liver tumor. The purpose of this study was to evaluate this technology in phantom and animal models. Using an electromagnetic navigation device, instrumented 18 g needles were advanced into radioopaque tumor targets in a respiratory liver phantom. The phantom featured a moving liver target that simulated cranio-caudal liver motion due to respiration. Skin-to-target path planning and real-time needle guidance were provided by a custom-designed software interface based on pre-operative 1 mm CT data slices. Needle probes were advanced using only the electromagnetic navigation device and software display. No conventional real-time imaging was used to assist in advancing the needle to the target. Two experienced operators (interventional radiologists) and two inexperienced ones (residents) used the system. The same protocol was then also used in two anesthetized 45 kg Yorkshire swine where radioopaque agar nodules were injected into the liver to serve as targets. A total of 76 tumor targeting attempts were performed in the liver phantom, and 32 attempts were done in the swine. The average time for path planning was 30 s in the phantom, and 63 s in the swine. The median time for the actual needle puncture to reach the desired target was 33 s in the phantom, and 42 s in the swine. The average registration error between the CT coordinate system and electromagnetic coordinate system was 1.4 mm (SD 0.3 mm) in the phantom, and 1.9 mm (SD 0.4 mm) in the swine. The median distance from the final needle tip position to the center of the tumor was 6.4 mm (SD 3.3 mm, n=76) in the phantom, and 8.3 mm (SD 3.7 mm, n=32) in the swine. There was no statistical difference in the planning time, procedure time, or accuracy of needle placement between experienced and inexperienced operators. The novel electromagnetic navigation system allows probe delivery into hepatic tumors of a physiologic phantom and live anesthetized swine. The system allows less experienced operators to perform equally well as experienced radiologists in terms of procedure time and accuracy of needle probe delivery.

Animals↗

Identification of exogenous forms of human-tropic porcine endogenous retrovirus in miniature Swine.

The replication of porcine endogenous retrovirus subgroup A (PERV-A) and PERV-B in certain human cell lines indicates that PERV may pose an infectious risk in clinical xenotransplantation. We have previously reported that human-tropic PERVs isolated from infected human cells following cocultivation with miniature swine peripheral blood mononuclear cells (PBMC) are recombinants of PERV-A with PERV-C. Here, we report that these recombinants are exogenous viruses in miniature swine; i.e., they are not present in the germ line DNA. These viruses were invariably present in miniature swine that transmitted PERV to human cells and were also identified in some miniature swine that lacked this ability. These data, together with the demonstration of the absence of both replication-competent PERV-A and recombinant PERV-A/C loci in the genome of miniature swine (L. Scobie, S. Taylor, J. C. Wood, K. M. Suling, G. Quinn, C. Patience, H.-J. Schuurman, and D. E. Onions, J. Virol. 78:2502-2509, 2004), indicate that exogenous PERV is the principal source of human-tropic virus in these animals. Interestingly, strong expression of PERV-C in PBMC correlated with an ability of the PBMC to transmit PERV-A/C recombinants in vitro, indicating that PERV-C may be an important factor affecting the production of human-tropic PERV. In light of these observations, the safety of clinical xenotransplantation from miniature swine will be most enhanced by the utilization of source animals that do not transmit PERV to either human or porcine cells. Such animals were identified within the miniature swine herd and may further enhance the safety of clinical xenotransplantation.

Animals↗

Respiratory symptoms and ventilatory capacity in swine confinement workers.

A group of 59 workers (41 men and 18 women) employed in swine confinement areas was studied to assess the presence of acute and chronic respiratory symptoms and the prevalence of abnormalities in ventilatory function. A control group of 46 (31 men and 15 women) unexposed workers was studied for the prevalence of chronic respiratory symptoms. For both male and female swine confinement workers complaints of chronic cough, dyspnoea, and chest tightness were significantly more frequent than among control workers. Male workers also complained more of chronic phlegm. Male swine confinement workers who were smokers had significantly higher prevalences of chronic cough, chronic phlegm, and chronic bronchitis than male non-smoking swine confinement workers. The frequency of acute symptoms associated with the workshift was high among the swine confinement workers with more than half of the workers complaining of cough and dyspnoea associated with work. Significant acute across shift reductions in lung function occurred in swine confinement workers, being largest for FEF25. All Monday preshift ventilatory capacity measurements in male confinement workers were significantly lower than predicted values; FVC and FEV1 were found to be lower than predicted values for women. The data indicate that exposure in swine confinement buildings is associated with the development of acute and chronic respiratory symptoms and impairment of lung function. Smoking appears to aggravate these changes.

Acute Disease↗

Nitric oxide production is maintained in exercising swine with chronic left ventricular dysfunction.

Left ventricular (LV) dysfunction caused by myocardial infarction (MI) is accompanied by endothelial dysfunction, most notably a loss of nitric oxide (NO) availability. We tested the hypothesis that endothelial dysfunction contributes to impaired tissue perfusion during increased metabolic demands as produced by exercise, and we determined the contribution of NO to regulation of regional systemic, pulmonary, and coronary vasomotor tone in exercising swine with LV dysfunction produced by a 2- to 3-wk-old MI. LV dysfunction resulted in blunted systemic and coronary vasodilator responses to ATP, whereas the responses to nitroprusside were maintained. Exercise resulted in blunted systemic and pulmonary vasodilator responses in MI that resembled the vasodilator responses in normal (N) swine following blockade of NO synthase with N(omega)-nitro-L-arginine (L-NNA, 20 mg/kg iv). However, L-NNA resulted in similar decreases in systemic (43 +/- 3% in N swine and 49 +/- 4% in MI swine), pulmonary (45 +/- 5% in N swine and 49 +/- 4% in MI swine), and coronary (28 +/- 4% in N and 35 +/- 3% in MI) vascular conductances in N and MI swine under resting conditions; similar effects were observed during treadmill exercise. Selective inhibition of inducible NO synthase with aminoguanidine (20 mg/kg iv) had no effect on vascular tone in MI. These findings indicate that while agonist-induced vasodilation is already blunted early after myocardial infarction, the contribution of endothelial NO synthase-derived NO to regulation of vascular tone under basal conditions and during exercise is maintained.

Adenosine Triphosphate↗

Race, poverty, and potential exposure of middle-school students to air emissions from confined swine feeding operations.

Previous studies suggest that airborne effluent from swine confined animal feeding operations (CAFOs) may affect the health and quality of life of adults and the prevalence of asthma symptoms among children. To investigate the extent to which public school students may be exposed to airborne effluent from swine CAFOs and to evaluate the association between schools' demographic characteristics and swine CAFO exposures, we assessed the proximity of 226 schools to the nearest swine CAFO and conducted a survey of school employees to identify schools with noticeable livestock odor. We used publicly available information describing the enrollment of each school to assess the association between race and socioeconomic status (SES) and swine CAFO exposure. Odor from livestock was noticeable outside (n = 47, 21%) and inside (n = 19, 8%) school buildings. Schools with < 63% enrollment of white students and > or = 47% of students receiving subsidized lunches at school were located closer to swine CAFOs (mean = 4.9 miles) than were the remaining schools (mean = 10.8 miles) and were more likely to be located within 3 miles of an operation than were schools with high-white/high-SES enrollment (prevalence ratio = 2.63; 95% confidence interval, 1.59-4.33). The prevalence of reported livestock odor varied with SES (low SES, 25%; high SES, 17%). These analyses indicate that the potential for in-school exposure to pollution arising from swine CAFOs in North Carolina and the environmental health risks associated with such exposures vary according to the racial and economic characteristics of enrolled students.

Adolescent↗

Pseudorabies virus propagated in rabbit kidney-derived RK13 cells is neutralized by natural IgM antibodies in normal swine serum which specifically lyse host cells.

Pseudorabies virus (PRV) propagated in rabbit kidney-derived RK-13 cells (PRV-RK) was neutralized by serum obtained from specific pathogen-free pigs through the activation of complement. The virus-neutralizing activity of swine serum was lost after treatment with ethylene glycol-bis-aminoethylether-N,N,N',N'-tetraacetic acid (EGTA) or ethylenediaminetetraacetic acid (EDTA). Anti-C1q and anti-IgM antibodies also inhibited virus-neutralizing activity. Though IgG-depleted swine serum neutralized PRV, IgM and IgG-free swine serum lost virus-neutralizing activity. Pre-incubation of swine serum with RK-13 cells, but not with swine kidney-derived CPK cells, at 4 degrees C eliminated the virus-neutralizing activity to PRV-RK. Results indicated that swine serum contained natural IgM against an antigen(s) on the RK-13 cell surface and that this surface antigen was integrated into the PRV envelope during the budding process. Thus the natural IgM in swine serum reacted with the RK-13 antigen on the viral envelope, activated the complement cascade and neutralized the PRV-RK.

Animals↗

Functional classification of swine manure management systems based on effluent and gas emission characteristics.

Gaseous emissions from swine (Sus scrofa) manure storage systems represent a concern to air quality due to the potential effects of hydrogen sulfide, ammonia, methane, and volatile organic compounds on environmental quality and human health. The lack of knowledge concerning functional aspects of swine manure management systems has been a major obstacle in the development and optimization of emission abatement technologies for these point sources. In this study, a classification system based on gas emission characteristics and effluent concentrations of total phosphorus (P) and total sulfur (S) was devised and tested on 29 swine manure management systems in Iowa, Oklahoma, and North Carolina in an effort to elucidate functional characteristics of these systems. Four swine manure management system classes were identified that differed in effluent concentrations of P and S, methane (CH4) emission rate, odor intensity, and air concentration of volatile organic compounds (VOCs). Odor intensity and the concentration of VOCs in air emitted from swine manure management systems were strongly correlated (r2 = 0.88). The concentration of VOC in air samples was highest with outdoor swine manure management systems that received a high input of volatile solids (Type 2). These systems were also shown to have the highest odor intensity levels. The emission rate for VOCs and the odor intensity associated with swine manure management systems were inversely correlated with CH4 and ammonia (NH3) emission rates. The emission rates of CH4, NH3, and VOCs were found to be dependent upon manure loading rate and were indirectly influenced by animal numbers.

Agriculture↗

Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States.

OBJECTIVE: To estimate the annual cost of infections attributable to porcine reproductive and respiratory syndrome (PRRS) virus to US swine producers. DESIGN: Economic analysis. SAMPLE POPULATION: Data on the health and productivity of PRRS-affected and PRRS-unaffected breeding herds and growing-pig populations were collected from a convenience sample of swine farms in the midwestern United States. PROCEDURE: Health and productivity variables of PRRS-affected and PRRS-unaffected swine farms were analyzed to estimate the impact of PRRS on specific farms. National estimates of PRRS incidence were then used to determine the annual economic impact of PRRS on US swine producers. RESULTS: PRRS affected breeding herds and growing-pig populations as measured by a decrease in reproductive health, an increase in deaths, and reductions in the rate and efficiency of growth. Total annual economic impact of these effects on US swine producers was estimated at dollar 66.75 million in breeding herds and dollar 493.57 million in growing-pig populations. CONCLUSIONS AND CLINICAL RELEVANCE: PRRS imposes a substantial financial burden on US swine producers and causes approximately dollar 560.32 million in losses each year. By comparison, prior to eradication, annual losses attributable to classical swine fever (hog cholera) and pseudorabies were estimated at dollar 364.09 million and dollar 36.27 million, respectively (adjusted on the basis of year 2004 dollars). Current PRRS control strategies are not predictably successful; thus, PRRS-associated losses will continue into the future. Research to improve our understanding of ecologic and epidemiologic characteristics of the PRRS virus and technologic advances (vaccines and diagnostic tests) to prevent clinical effects are warranted.

Animal Husbandry↗

Stimulation of lipogenesis by insulin in swine adipose tissue: antagonism by porcine growth hormone.

The effects of physiological (1, 10 ng/ml) and pharmacological (1,000 ng/ml) concentrations of insulin (INS) and porcine growth hormone (pGH) on lipid metabolism were determined in short-term (2 h) and long-term (26, 50 h) incubations of swine adipose tissue. The short-term effects of three different commercial sources of bovine serum albumin (BSA) on adipose tissue metabolism were also evaluated. Two of the three BSA preparations were found to be unsuitable for inclusion in the short-term incubation buffer because they caused a stimulation of lipid synthesis in adipose tissue and masked the stimulatory effects of insulin. Physiological concentrations of insulin stimulated glucose metabolism in 2-h incubations by 100% in adipose tissue from 80-kg swine. After a 26-h incubation period, INS maintained rates of glucose metabolism at levels comparable to maximally stimulated rates in fresh tissue. Insulin also enhanced glucose metabolism following 50-h incubations; however, rates were less than for 2- or 26-h incubations. Glucose metabolism was also stimulated in adipose tissue from 127-kg swine when incubated for 2 h with INS; however, INS responsiveness declined with increasing body weight. Lipogenesis and glucose oxidation were partially maintained by INS using tissue from the heavier swine. A pharmacological but not physiological concentration of pGH stimulated glucose metabolism in short-term incubations by 50% in adipose tissue from 80-kg swine, and by 10% in adipose tissue from 127-kg swine. Long-term culture of adipose tissue in the presence of pGH had no effect on glucose metabolism. Physiological levels of pGH directly antagonized the stimulation of glucose metabolism by INS in short- and long-term incubations. In summary, these results are the first to establish that swine adipose tissue is quite sensitive to insulin and that pGH directly antagonizes insulin action.

Adipose Tissue↗

Airway responses of healthy farmers and nonfarmers to exposure in a swine confinement building.

OBJECTIVES: The objective of the study was to determine whether swine farmers continuously exposed to the farming environment react differently to acute exposure than previously unexposed nonfarmers. METHODS: Nine healthy nonfarmers, not previously exposed to a farming environment, and eight swine farmers were exposed in a swine confinement building for 3 hours while weighing pigs. Lung function measurements, methacholine challenge tests, and nasal lavages were performed before and after the exposure. Blood samples were drawn repeatedly during the exposure day. Differential cell counts and cytokine levels were analyzed in the nasal lavage fluid and blood. RESULTS: The exposure levels were the same in both groups. Bronchial responsiveness to methacholine increased by a median of 4.0 (25th-75th percentiles 2.2-10.1 among the nonfarmers) and 0.7 (25th-75th percentiles 0.01-3.5 among the farmers) doubled concentration steps. The median serum levels of interleukin-6 increased from 3.8 (25th-75th percentiles <3-5.8) ng/l to 23.7 (25th-75th percentiles 11.6-41.6) ng/l among the nonfarmers and from <3 to 3.8 (25th-75th percentiles 3.1-11.6) ng/l among the swine farmers after the exposure. Swine dust exposure induced a ninefold increase in the total cell counts in the nasal lavage fluid of the nonfarmers, but no significant increase among the swine farmers. CONCLUSIONS: The exposure altered lung function and bronchial responsiveness, as well as cell number and cytokines in blood and nasal lavage fluid in previously unexposed nonfarming subjects, whereas only minor alterations were found in the farmers. This finding suggests possible adaptation mechanisms in chronically exposed swine farmers.

Adolescent↗

Chronic morphine administration impairs cell-mediated immune responses in swine.

Swine were used as an experimental animal model to evaluate immunomodulating effects of the opiate drug, morphine, on antigen-specific humoral and cell-mediated immune responses. Morphine free base in peanut oil was administered at 4-day intervals for up to 42 days to maintain drug levels at or above 100 ng/ml. The effect of morphine administration on humoral immune responses was evaluated by immunization on day 7 of morphine treatment with a battery of antigens, including swine herpes virus (also known as pseudorabies virus, PRV), Brucella abortus and the Escherichia coli pilus antigens K88, K99, 987P and F41. Fourteen days later, swine were reimmunized with B. abortus and E. coli pilus antigens. Antibody titers to these antigens were evaluated on a weekly basis. Cell-mediated immunity was evaluated by measuring skin immune responses to the antigen 2,4-dintroflurobenozene (DNFB). In one experiment, swine were sensitized with DNFB on day 7 of morphine treatment at the same time as immunization with the other antigens. In a second series of experiments, swine were sensitized either 7 days before or 7 days after initiation of morphine treatment. Pigs were challenged with DNFB administered 27 days after the initiation of morphine treatment and skin responses were evaluated 24 h later. The ability of swine to resist PRV infection was evaluated by exposure to virulent virus on day 28 of morphine treatment. Chronic morphine administration did not impair the induction of the humoral immune responses to bacterial or viral antigens. In addition, morphine treatment did not alter the resistance of immunized swine to PRV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗