Diet-induced obesity alters anabolic signalling in mice at the onset of skeletal muscle regeneration.

AIM: Obesity is classified as a metabolic disorder that is associated with delayed muscle regeneration following damage. For optimal skeletal muscle regeneration, inflammation along with extracellular matrix remodelling and muscle growth must be tightly regulated. Moreover, the regenerative process is dependent on the activation of myogenic regulatory factors (MRFs) for myoblast proliferation and differentiation. The purpose of this study was to determine how obesity alters inflammatory and protein synthetic signalling and MRF expression at the onset of muscle regeneration in mice. METHODS: Forty-eight male C57BL/6J mice (3 weeks old) were randomly assigned to either a high-fat diet (HFD, 60% fat) or a lean diet (10% fat) for 12 weeks. At 15 weeks, bupivacaine was injected into the tibialis anterior (TA) of the injured group (n = 5-8/group) and PBS was injected into the control (n = 5-6). The TA was excised 3 or 28 days after injection. RESULTS: We demonstrated impaired muscle regeneration in obese mice. The obese mice had reduced IL-6, MyoD and IGF-1 mRNA abundance compared to the lean mice (P < 0.05). Three days following muscle damage, TNF-α mRNA and protein levels of P-STAT3 and P-Akt were 14-fold, fourfold and fivefold greater in the lean mice respectively. However, there were no differences observed in the obese injured group compared to the uninjured group. Moreover, p70S6K1 was threefold greater in lean injured mice compared to uninjured but was reduced by 28% in the obese injured mice. CONCLUSION: Obese mice have impaired inflammatory and protein synthetic signalling that may negatively influence muscle regeneration.

Characterization of hydrogen responsive nanoporous palladium films synthesized via a spontaneous galvanic displacement reaction.

A model is presented regarding the mechanistic properties associated with the interaction of hydrogen with nanoporous palladium (np-Pd) films prepared using a spontaneous galvanic displacement reaction (SGDR), which involves PdCl(2) reduction by atomic Ag. Characterization of these films shows both chemical and morphological factors, which influence the performance characteristics of np-Pd microcantilever (MC) nanomechanical sensing devices. Raman spectroscopy, uniquely complemented with MC response profiles, is used to explore the chemical influence of palladium oxide (PdO). These combined techniques support a reaction mechanism that provides for rapid response to H(2) and recovery in the presence of O(2). Post-SGDR processing via reduction of PdCl(2)(s) in a H(2) environment results in a segregated nanoparticle three-dimensional matrix dispersed in a silver layer. The porous nature of the reduced material is shown by high resolution scanning electron microscopy. Extended grain boundaries, typical of these materials, result in a greater surface area conducive to fast sorption/desorption of hydrogen, encouraged by the presence of PdO. X-ray diffraction and inductively coupled plasma-optical emission spectroscopy are employed to study changes in morphology and chemistry occurring in these nanoporous films under different processing conditions. The unique nature of chemical/morphological effects, as demonstrated by the above characterization methods, provides evidence in support of observed nanomechanical response/recovery profiles offering insight for catalysis, H(2) storage and improved sensing applications.

Angiotensin-converting enzyme genotype and physical performance during US Army basic training.

Prior studies have suggested that angiotensin I-converting enzyme (ACE) genotype correlates with superior physical performance in highly selected populations. This study assessed whether such an association exists in a heterogeneous population. Using polymerase chain reaction techniques, we determined the ACE genotypes (insertion/insertion, deletion/insertion, or deletion/deletion) of 62 male and 85 female US Army recruits. Before and after 8 wk of basic training, we determined peak oxygen uptake and performance on the Army Physical Fitness Test (APFT), which includes standardized measures of muscular endurance (sit-ups, push-ups) and a 2-mile run. Subjects of different ACE genotypes had similar peak oxygen uptakes and APFT scores, both before and after training. Subjects with genotype II had higher APFT scores than others, but the differences were not statistically significant. Furthermore, no ACE genotype group had a performance advantage in analyses that adjusted for baseline fitness. We conclude that ACE genotype does not have a strong effect on aerobic power or muscular endurance in healthy, young American adults drawn from an ethnically and geographically diverse population.

Risk factors for training-related injuries among men and women in basic combat training.

PURPOSE: Past investigations indicate that training-related injuries are associated with certain performance-oriented measures of physical fitness and certain lifestyle characteristics. This study examined associations between injuries, direct (physiological) measures of physical fitness, and lifestyle characteristics. METHODS: Subjects were 756 men and 474 women performing the standardized activities involved in U.S. Army Basic Combat Training (BCT). Before BCT, a subsample of subjects (182 men and 168 women) were administered a series of tests that included a treadmill running test (peak VO2), dual-energy x-ray absorptiometry (for body composition), several measures of muscle strength, a hamstring flexibility test, and a vertical jump. A questionnaire addressed smoking habits and prior physical activity. All subjects were administered the Army Physical Fitness test consisting of push-ups, sit-ups, and a 3.2-km run. Gender, age, stature, and body mass were obtained from physical examination records. Injuries incurred during BCT were transcribed from medical records; for each medical visit, the diagnosis, anatomical location, disposition (final outcome of visit), and days of limited duty were recorded. RESULTS: Women had over twice the injury rate of men. For men and women, fewer push-ups, slower 3.2-km run times, lower peak VO2, and cigarette smoking were risk factors for time-loss injury. Among the men only, lower levels of physical activity before BCT and both high and low levels of flexibility were also time-loss injury risk factors. Multivariate analysis revealed that lower peak VO2 and cigarette smoking were independent risk factors for time-loss injury. CONCLUSIONS: Lower aerobic capacity and cigarette smoking were independently associated with a higher likelihood of injury in both men and women during a standardized program of physical training. Further studies are needed to assess associations between injury and body composition and muscular strength.

The prevalence of exercise-induced bronchospasm among US Army recruits and its effects on physical performance.

STUDY OBJECTIVES: To measure the prevalence of exercise-induced bronchospasm (EIB) and to determine its effect on the physical performance response to training in otherwise healthy young adults. DESIGN: Observational, retrospective study. SETTING: Fort Jackson, SC, May to July 1998. PARTICIPANTS: One hundred thirty-seven ethnically diverse US Army recruits undergoing an 8-week Army basic training course. MEASUREMENTS AND RESULTS: Subjects underwent exercise challenge testing at the end of basic training to evaluate for EIB (defined as a decrease in FEV(1) of > or = 15%, 1 or 10 min after running to peak oxygen uptake on a treadmill). Those subjects who were unable to run to peak oxygen uptake, or who were unable to perform two baseline FEV(1) maneuvers the results of which were within 5% of each other, were excluded from analysis. We measured peak oxygen uptake on a treadmill and the scores achieved on the components of the US Army physical fitness test (APFT). Of 137 subjects, 121 (58 men and 63 women) met our inclusion criteria. Eight subjects (7%) had EIB. Subjects who experienced EIB and unaffected control subjects both showed statistically significant gains in performance on the APFT events during basic training. At the end of basic training, peak oxygen uptake levels and APFT event scores were not significantly different between subjects with EIB and unaffected control subjects. CONCLUSIONS: Seven percent of the US Army recruits who were tested had EIB, but this did not hinder their physical performance gains during basic training. EIB per se should not be an absolute reason to exclude individuals from employment in jobs with heavy physical demands.

Evaluation of anthropometric equations to assess body-composition changes in young women.

BACKGROUND: Healthy young women who engage in an exercise program may lose fat that is not reflected in body weight changes because of concurrent gains in fat-free mass (FFM). OBJECTIVE: This study addressed the question of how well anthropometry-based predictive equations can resolve these changes. DESIGN: Several widely used skinfold-thickness- or circumference-based equations were compared by using dual-energy X-ray absorptiometry to study 150 healthy young women before and after 8 wk of Army basic combat training (average energy expenditure: 11.7 MJ/d). RESULTS: Women lost 1.2 +/- 2.6 kg fat (mean +/- SD) and gained 2.0 [corrected] +/- 1.5 kg FFM. Fat loss (r = 0.47), but not FFM gain (r = 0.01), correlated with initial fatness. Thus, for many women who lost fat, body weight did not change or increased. Fat loss was associated with a reduction in abdominal circumference but this alone was not a consistent marker of fat loss. One circumference equation and one skinfold-thickness equation yielded the smallest residual SDs (2.0% and 1.9% body fat, respectively) compared with the other equations in predicting body fat. The sensitivity and specificity of the best equations in predicting changes in percentage body fat were not better than 55% and 66%, respectively. CONCLUSIONS: These data suggest that for women, anthropometry can provide better estimates of fatness than body mass index but it is still relatively insensitive to short-term alterations in body composition. Not surprisingly, the circumference equation that includes the most labile sites of female fat deposition (ie, waist and hips instead of upper arm or thigh) proved to be the most reliable.

The effects of choline supplementation on physical performance.

It has been reported that plasma choline levels decrease following certain types of strenuous exercise. Preliminary findings also suggest that a drop in plasma choline may limit physical performance, while choline supplementation may delay fatigue during prolonged efforts. A double-blind crossover design was used to determine the relationship between plasma choline and performance during and after 4 hr of strenuous exercise. Volunteers (N = 14) received either a placebo or treatment beverage (8.425 g choline citrate) prior to and midway through a 4-hr load carriage treadmill exercise (3% grade at 5.6 km/h 3 20 km) carrying a total load of 34.1 kg. Following the treadmill test, run time-to-exhaustion and squat tests were performed, and perceived exertion, plasma choline, glycerophosphocholine, and phosphatidylcholine were measured. Plasma choline levels increased 128% after the run-to-exhaustion with the choline supplemented beverage but remained unchanged with the placebo beverage. No significant effects were seen with choline supplementation on any outcome performance measure. Consequently, soldiers conditioned to carry heavy loads over long distances do not deplete plasma choline as a result of a prolonged exhaustive exercise under a placebo beverage, nor do they benefit from choline supplementation to delay fatigue under the same conditions.

Phylogenetic characterization of a highly attenuated strain of equine arteritis virus from the semen of a persistently infected standardbred stallion.

An avirulent, novel variant of equine arteritis virus (EAV; CA95G) was isolated from the semen of a persistently infected Standardbred stallion. The CA95G virus caused subclinical infection and seroconversion in susceptible horses, and virus was isolated only once from blood and nasal secretions collected from 6 experimentally infected horses. Sequence analysis of genes encoding the known EAV structural proteins shows that this highly attenuated strain of EAV is genetically similar to virulent field strains of EAV and, in particular, to a strain of EAV that was isolated during an outbreak of equine viral arteritis in western Canada in 1986. Not only is the carrier stallion the critical natural reservoir of EAV, but genetic diversity of the virus is generated in the course of persistent infection of carrier stallions. The subtle genetic changes that facilitate and maintain persistent EAV infection of the stallion's reproductive tract likely influence phenotypic properties of the virus such as virulence.

Acute hormonal responses to a single bout of heavy resistance exercise in trained power lifters and untrained men.

The purpose of this study was to investigate the acute responses of both stress and fluid regulatory hormones to a single bout of resistance exercise in both trained and untrained men. Seven competitive power lifters (PL) and 12 untrained subjects (UT) performed one set of the leg press exercise to exhaustion at 80% of their respective one-repetition maximum. Blood samples were obtained twice prior to exercise (at P1 and P2), immediately postexercise (IP), and at 5 minutes postexercise (5PE). Compared to P1 and P2, plasma epinephrine, norepinephrine, dopamine, atrial peptide, osmolality, and blood lactic acid increased significantly (p < or = 0.05) at IP. Plasma epinephrine, norepinephrine, atrial peptide, and blood lactic acid concentrations remained elevated at 5PE compared to P1 and P2. Plasma renin activity and angiotensin II were significantly elevated at 5PE compared to P1, P2, and IP, and this increase was significantly greater in PL compared to UT at 5PE. These data indicate that an acute bout of resistance exercise dramatically affects secretion of stress and fluid regulatory hormones.

Passive transfer, rate of decay, and protein specificity of antibodies against equine arteritis virus in horses from a Standardbred herd with high seroprevalence.

OBJECTIVE: To determine rate of decay of passively acquired antibodies in Standardbred foals on a farm with a high seroprevalence to equine arteritis virus (EAV) and to determine whether vertical or horizontal transmission of the virus was responsible for infection on the farm. DESIGN: Repeated-measures study. ANIMALS: 46 Standardbred horses (15 brood mares and their foals, 5 stallions, and 11 young horses). PROCEDURE: Serum samples obtained from horses on the farm were evaluated by serum neutralization and western immunoblot analysis to detect EAV-specific antibodies. The half-life of passively acquired antibodies in foals was estimated by use of regression analysis. RESULTS: Most (14/15) of the mares evaluated were seropositive to EAV. After suckling, their foals were also seropositive. Mean biological half-life for passively acquired antibodies in serum samples obtained from foals was 32 days (r2 = 0.61). The foal born to a seronegative dam and all 11 young horses from the farm were seronegative to EAV. At least 2 of 5 stallions on the farm were persistently infected carriers that were shedding virus in their semen. Immunoblot analysis of seropositive serum samples most consistently recognized the M protein of EAV. CLINICAL IMPLICATIONS: Analysis of these data indicated that a modified-live EAV vaccine can be administered to foals after they are 8 months old without risk of interference from maternal antibodies, regardless of serologic status of the foal's dam. Horizontal transmission of EAV via the respiratory tract apparently was uncommon on the farm, indicating that mares primarily were infected by venereal transmission of virus from carrier stallions.

Serologic response of horses to the structural proteins of equine arteritis virus.

Equine arteritis virus (EAV) is the causative agent of equine viral arteritis, an apparently emerging disease of equids. In this study, the antibody response of horses to the structural proteins of EAV was evaluated using gradient-purified EAV virions and baculovirus-expressed recombinant EAV structural proteins (G(L), G(S), M, N) as antigens in a Western immunoblotting assay. Thirty-three sera from horses that previously had been naturally or experimentally infected with EAV were evaluated, including samples from mares, geldings, and both persistently and nonpersistently infected stallions. Sera also were evaluated from 4 horses that had been vaccinated with the commercial modified live EAV vaccine. The data suggest that the serologic response of individual horses to EAV may vary with the infecting virus strain and duration of infection. The M protein was most consistently recognized by the various serum samples, whereas the response to the N and G(L) proteins was variable and the G(S) protein was bound by only 1 serum sample. The immunoblotting assay definitively established the protein specificity of the humoral response of horses to EAV; however, it clearly is less sensitive than the standard serum neutralization (SN) test--2 of the 37 sera that were seropositive by the SN test failed to react in the immunoblot assay with any EAV structural protein. Furthermore, the G(L) protein expresses the known neutralization determinants of EAV, yet only 22 of the 37 sera that had SN antibodies bound the G(L) protein in the immunoblotting assay. Information from this study will assist ongoing efforts to develop improved methods for the serologic diagnosis of EAV infection of horses.

Comparison of body composition assessment among lean black and white male collegiate athletes.

Variations in the density of the fat-free mass (DFFM) across ethnic groups is a critical factor that invalidates the use of body fat equations. It has also been suggested that resistance trained athletes may have higher body densities (BDs) than untrained subjects. Thus, the validity of using anthropometric (ANT) equations, which have mainly been derived on white nonathletic groups, has been questioned for athletic white and black men. This study compared BD and percent body fat (%BF) between 34 white (20 +/- 1 yr, 184 +/- 11 cm, 84 +/- 12 kg, 25 +/- 3 BMI) and 30 black (20 +/- 1 yr, 182 +/- 9 cm, 84 +/- 12 kg, 25 +/- 2 BMI) male collegiate athletes and determined the accuracy of 5 ANT equations in estimating %BF. Subjects were underwater weighed (UWW), and skinfold measurements were obtained from the chest, mid-axillary, abdomen, suprailiac, subscapula, triceps, and thigh. BD was obtained from UWW and estimated from the five skinfold equations. From UWW, significant (P < or = 0.05) differences were found for BD (1.075 +/- 0.007 vs 1.0817 +/- 0.009), but not for %BF (10.49 +/- 2.8 vs 11.59 +/- 3.4) for white and black subjects, respectively. Differences were noted for subcutaneous skinfold sites (abdominal (vertical), suprailiac, and thigh), sum of three and seven skinfolds, and proportion of subscapular subcutaneous fat. One out of five and five out of five ANT equations (Siri conversions) yielded significantly lower estimates compared with UWW %BF for the white and black athletes, respectively. Use of the Schutte equation for the black athletes resulted in overpredictions of %BF for five out of five equations. In addition, the Schutte equation offered slightly greater accuracy than did the Siri equation for estimating %BF in black athletes. These data confirm earlier concerns that ANT equations derived on general populations may not be as accurate for athletic populations and also suggest that correction equations are necessary for converting BD into %BF for populations differing with respect to race or training status.

Gender comparison of peak oxygen uptake: repetitive box lifting versus treadmill running.

The gender differences in peak oxygen uptake (VO2peak) for various modes of exercise have been examined previously; however, no direct gender comparisons have been made during repetitive lifting (RL). In the present study the VO2peak between RL and treadmill running (TR) was compared between 20 men [mean (SD) age, height, body mass and body fat: 21 (3) years, 1.79 (0.06) m, 81 (9) kg, 19 (6)%, respectively] and 20 women [mean (SD) age, height, body mass and body fat: 21 (3) years, 1.63 (0.05) m, 60 (7) kg, 27 (6)%, respectively]. VO2peak (l x min[-1]), defined as the highest value obtained during exercise to volitional fatigue, was determined using discontinuous protocols with treadmill grade or box mass incremented to increase exercise intensity. For RL VO2peak, a pneumatically driven shelf was used to lower a loaded box to the floor, and subjects then lifted the box, at a rate of 15 lifts x min(-1). VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and minute ventilation (VE, l x min[-1]) were determined using an on-line gas analysis system. A two-way repeated measures analysis of variance revealed significant gender effects, with men having higher values for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE, but women having higher values of the ventilatory equivalent for oxygen (VE/VO2). There were also mode of exercise effects, with TR values being higher for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE and an interaction effect for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE/VO2. The women obtained a greater percentage (approximately 84%) of their TR VO2peak during RL than did the men (approximately 79%). There was a marginal tendency for women to decrease and men to increase their VE/VO2 when comparing TR with RL. The magnitude of the gender differences between the two exercise modalities appeared to be similar for heart rate, VE and R, but differed for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]). Lifting to an absolute height (1.32 m for the RL protocol) may present a different physical challenge to men and women with respect to the degree of involvement of the muscle groups used during lifting and ventilation.

Physical performance and metabolic recovery among lean, healthy men following a prolonged energy deficit.

Previous studies have demonstrated that full recovery from weight loss may take months or years. The present investigation examined short-term recovery (5 wks "post") of physical performance (muscular strength, muscular power, vertical jump), body composition, metabolic hormones (testosterone, luteinizing hormone, sex hormone binding globulin, insulin-like growth factor-1, triiodothyronine, thyroxine, thyroid binding globulin, and thyroid-stimulating hormone) and metabolic markers (transferrin, ferritin, prealbumin, glycerol, nonesterified fatty acids, high-density lipoproteins, and lactate) in 10 healthy young men after an 8-week Army course with an energy deficit (1000 kcal/d) and loss of body mass (-12%). Subjects ate ad libitum after the course ended ("post"). Body composition was determined by dual-energy X-ray absorptiometry; strength from a simulated power clean, power from body mass and jump height, and metabolic hormones were measured in morning-fasted blood by radioimmunoassay. With the exception of transferrin and glycerol, all study parameters were significantly (p<.05) altered by the training course. At 5 weeks post fat-free mass along with all physical performance measures returned to initial levels; however, fat mass had significantly (p<.05) increased over initial levels. Also, with the exception of lactate, all measured hormones and markers were close to initial levels and within normal ranges. Reported complications during recovery included sleep irregularities, diarrhea, loss of motivation and feelings of fatigue. While the long range effect of this energy deprivation experience is uncertain, these data do suggest that severe weight loss does not result in lasting alterations of the contractile and metabolic properties of skeletal muscle in young, lean, healthy men.

Neutralization determinants of laboratory strains and field isolates of equine arteritis virus: identification of four neutralization sites in the amino-terminal ectodomain of the G(L) envelope glycoprotein.

The N-terminal hydrophilic ectodomain of the G(L) envelope glycoprotein of equine arteritis virus (EAV) contains neutralization determinants of the virus. We developed a panel of 17 neutralizing murine monoclonal antibodies (MAbs) to further characterize the neutralization determinants of EAV. Included were 6 MAbs previously raised against a laboratory strain (EAVUCD) of the original Bucyrus strain of EAV, as well as 11 additional MAbs that were raised against a neutralization-resistant variant [escape mutant (EM)] virus (EM6D10) that was derived from EAVUCD. All MAbs raised against EAVUCD and 4 of the MAbs raised against EM6D10 (2B3, 5F8, 8D4, and 10B4) reacted with the corresponding G(L) envelope glycoprotein in a Western immunoblotting assay, whereas the remaining 7 MAbs raised against EM6D10 did not react with any viral protein in the immunoblotting assay but competitively inhibited the binding of MAbs 2B3, 5F8, 8D4, and 10B4, indicating that they also recognize epitopes on the G(L) protein. A panel of 18 EM viruses raised to the MAb panel, 19 field isolates of EAV from North America and Europe, the modified-live virus vaccine (ARVAC), and 3 other laboratory strains of EAV were characterized by microneutralization assay with the panel of neutralizing MAbs and polyclonal rabbit and horse antisera. Comparative analysis of the nucleotide sequences of ORF5 and the deduced amino acid sequences of the G(L) protein of individual EM viruses and field isolates of EAV identified four distinct neutralization sites. These sites include amino acids 49 (site A), 61 (site B), 67 through 90 (site C), and 99 through 106 (site D). With the notable exception of site A, the sites were all located in the V1 variable region (amino acids 61-121) within the second half of the N-terminal hydrophilic ectodomain of the G(L) protein. Site D includes several overlapping linear epitopes which appear to interact with amino acids in the other three sites to form conformationally dependent epitopes. Amino acid substitutions within any of these four sites can alter the neutralization phenotype of individual strains of EAV.

Isolation of a poxvirus from a black-tailed deer (Odocoileus hemionus columbianus).

A poxvirus was isolated during the latter half of 1993 from a black-tailed deer (Odocoileus hemionus columbianus) that died of fulminant adenovirus infection in California (USA). The poxvirus was isolated from a pooled tissue homogenate, after repeated serial blind passages in primary black-tailed deer testicular cells. Based on electron microscopic examination of the virus, we observed morphologic features typical of the genus Orthopoxvirus, although definitive characterization was not done.

Regional fat placement in physically fit males and changes with weight loss.

The abdomen is the principal site of fat deposition in men, and because abdominal fat is readily mobilized during exercise, the relative proportion of fat in the abdominal site may negatively correlate with the amount of regular physical activity, and even with physical fitness. This study presents data for regional fatness in 165 fit young men (U.S. Army Ranger candidates; initial body fat = 14.7 +/- 4.7%) assessed by dual-energy x-ray absorptiometry (DEXA), and for relative changes occurring following a 13% weight loss produced by a 1000 kcal.d-1 energy deficit over 8 wk. Fat-free mass was constant across quintiles of percent body fat; only fat mass was different (16.2 +/- 2.2 kg and 6.0 +/- 1.4 kg at upper and lower quintiles, respectively). Truncal fat accounted for about 41% of total body fat in all quintiles; only the proportion of fat distributed to the arms was significantly higher in the fattest quintiles of men. Among a group of less intensely trained soldiers with the same average fatness as the highest quintile of Ranger students (20%), relative fat distribution to the trunk approached 50% of the total fat. Following weight loss, Ranger students lost half of the fat in all regions assessed (legs, arms, and trunk). The only significant association between regional losses and initial fatness was a greater proportion of fat lost from the arms in the fattest Rangers. These data suggest a "fit fat" distribution in active young men in which fat remains in the arms and legs until extreme weight loss occurs and the metabolically more active abdominal fat approaches depletion.

Susceptibility of Culicoides variipennis sonorensis to infection by polymerase chain reaction-detectable bluetongue virus in cattle blood.

Cattle bloods containing only polymerase chain reaction (PCR)--detectable bluetongue-10 viral nucleic acid, but as determined by virus isolation techniques, not bluetongue-10 virus, were incapable of infecting intrathoracically inoculated Culicoides variipennis sonorensis. These insects also failed to transmit bluetongue-10 virus when fed on sheep. Cattle whose blood contain only PCR-detectable bluetongue viral nucleic acid, but no infectious virus, are unlikely to play a role in the epidemiology of bluetongue. The biological significance of PCR-based detection assays and their effect on animal health regulations on the international trade of livestock and livestock germplasm is discussed. Bluetongue virus infection provides a very useful model with which to study arthropod-transmitted RNA virus infections of humans and other animals.

Systemic adenovirus infection associated with high mortality in mule deer (Odocoileus hemionus) in California.

Seventeen counties in northern California experienced epizootics of high mortality in the mule deer (Odocoileus hemionus) population during the latter half of 1993. Thirteen deer submitted to the California Veterinary Diagnostic Laboratory System as part of this natural die-off had systemic adenovirus infection. Pulmonary edema was present in all 13 deer. Erosions, ulceration, and abscessation of the upper alimentary tract occurred in 7/13 deer. Four of 13 deer had hemorrhagic enteritis. All 13 deer had widespread systemic vasculitis with endothelial intranuclear inclusions. Fluorescein isothiocyanate-labeled antibody directed against bovine adenovirus type 5 bound to antigen in endothelial cells. Adenovirus was identified by transmission electron microscopy within the nuclei of endothelial cells in 6/6 deer examined. An adenovirus was isolated from lung homogenates of one deer that were cultured on black-tailed deer pulmonary artery endothelial cells. With the exception of the intranuclear inclusions evident on histologic evaluation, gross and histologic changes were similar to those described for bluetongue virus infection and epizootic hemorrhagic disease virus infection in white-tailed deer. Nine additional deer were emaciated and had pharyngeal abscesses with focal vasculitis, which may represent the chronic affects of previous nonfatal adenovirus infection.