Turnover of stable carbon isotopes in the muscle, liver, and breath CO2 of alpacas (Lama pacos).

Stable carbon isotope analysis of animal liver and muscle has become a widespread tool for investigating dietary ecology. Nonetheless, stable carbon isotope turnover of these tissues has not been studied in large mammals except with isotopically labelled tracer methodologies, which do not produce carbon half-lives analogous to those derived from naturalistic diet-switch experiments. To address this gap, we studied turnover of carbon isotopes in the liver, muscle, and breath CO2 of alpacas (Lama pacos) by switching them from a C3 grass diet to an isonitrogenous C4 grass diet. Breath samples as well as liver and muscle biopsies were collected and analyzed for up to 72 days to monitor the incorporation of the C4-derived carbon. The data suggest half-lives of 2.8, 37.3, and 178.7 days for alpaca breath CO2, liver, and muscle, respectively. Alpaca liver and muscle carbon half-lives are about 6 times longer than those of gerbils, which is about what would be expected given their size. In contrast, breath CO2 turnover does not scale readily with body mass. We also note that the breath CO2 and liver data are better described using a multiple-pool exponential decay model than a single-pool model.

Effect of pulsed ultrasound in combination with gentamicin on bacterial viability in biofilms on bone cements in vivo.

AIMS: The aim of this study is to investigate whether pulsed ultrasound (US) in combination with gentamicin yields a decreased viability of bacteria in biofilms on bone cements in vivo. METHODS AND RESULTS: Bacterial survival on bone cement in the presence and absence of ultrasound was compared in a rabbit model. Two bone cement samples with an Escherichia coli ATCC 10798 biofilm were implanted in a total of nine rabbits. In two groups bone cement discs loaded with gentamicin, freshly prepared and aged were used, and in one group unloaded bone cement discs in combination with systemically administered gentamicin. Pulsed ultrasound with a frequency of 28.48 kHz and a maximum acoustic intensity of 500 mW cm(-2) was applied continuously from 24 h till 72 h postsurgery on one of the two implanted discs. After euthanization and removal of the bacteria from the discs, the number of viable bacteria were quantified and skin samples were analysed for histopathological examination. Application of ultrasound, combined with gentamicin, reduced the viability of the biofilms in all three groups varying between 58 and 69% compared with the negative control. Histopathological examinations showed no skin lesions. CONCLUSIONS: Ultrasound resulted in a tendency of improved efficacy of gentamicin, either applied locally or systemically. Usage of ultrasound in this model proved to be safe. SIGNIFICANCE AND IMPACT OF THE STUDY: This study implies that ultrasound could improve the prevention of infection immediately after surgery, especially because the biomaterials, gentamicin and ultrasound used in this model are all in clinical usage, but not yet combined in clinical practice.

Ultrasonically enhanced vancomycin activity against Staphylococcus epidermidis biofilms in vivo.

Infection of implanted medical devices by Gram-positive organisms such as Staphylococcus ssp. is a serious concern in the biomaterial community. In this research the application of low frequency ultrasound to enhance the activity of vancomycin against implanted Staphylococcus epidermidis biofilms was examined. Polyethylene disks covered with a biofilm of S. epidermidis were implanted subcutaneously in rabbits on both sides of their spine. The rabbits received systemic vancomycin for the duration of the experiment. Following 24 h of recovery, one disk was insonated for 24 or 48 h while the other was a control. Disks were removed and viable bacteria counted. At 24 h of insonation, there was no difference in viable counts between control and insonated biofilms, while at 48 h of insonation there were statistically fewer viable bacteria in the insonated biofilm. The S. epidermidis biofilms responded favorably to combinations of ultrasound and vancomycin, but longer treatment times are required for this Gram-positive organism than was observed previously for a Gram-negative species.

Pulsed ultrasound enhances the killing of Escherichia coli biofilms by aminoglycoside antibiotics in vivo.

Escherichia coli biofilms on two polyethylene disks were implanted subcutaneously into rabbits receiving systemic gentamicin. Ultrasound was applied for 24 h to one disk. Both disks were removed, and viable bacteria were counted. Pulsed ultrasound significantly reduced bacterial viability below that of nontreated biofilms without damage to the skin.

Ultrasonic enhancement of antibiotic action on Escherichia coli biofilms: an in vivo model.

Biofilm infections are a common complication of prosthetic devices in humans. Previous in vitro research has determined that low-frequency ultrasound combined with aminoglycoside antibiotics is an effective method of killing biofilms. We report the development of an in vivo model to determine if ultrasound enhances antibiotic action. Two 24-h-old Escherichia coli (ATCC 10798) biofilms grown on polyethylene disks were implanted subcutaneously on the backs of New Zealand White female rabbits, one on each side of the spine. Low-frequency (28.48-kHz) and low-power-density (100- and 300-mW/cm2) continuous ultrasound treatment was applied for 24 h with and without systemic administration of gentamicin. The disks were then removed, and the number of viable bacteria on each disk was determined. At the low ultrasonic power used in this study, exposure to ultrasound only (no gentamicin) caused no significant difference in bacterial viability. In the presence of antibiotic, there was a significant reduction due to 300-mW/cm2 ultrasound (P = 0.0485) but no significant reduction due to 100-mW/cm2 ultrasound. Tissue damage to the skin was noted at the 300-mW/cm2 treatment level. Further development of this technique has promise in treatment of clinical implant infections.

The inhibitory effects of bryostatin 1 administration on the growth of rabbit papillomas.

Bryostatin 1 is a protein kinase C modulator that shows antineoplastic activity in a variety of tumor systems. This study examined the effects of bryostatin 1 administration on papilloma growth in rabbits. Investigations of optimal route, dose, and schedule were performed. Several groups of rabbits were inoculated with cottontail rabbit papillomavirus (CRPV) DNA. Bryostatin 1 was administered i.v., both daily and weekly, and intralesionally both weekly and bi-weekly. Intralesionally dosed papillomas were examined histologically for immune cell infiltration. In weekly and daily i.v. trials, 2.5 and 1.0 microg/kg, respectively, showed the greatest overall reduction in tumor size. Bryostatin 1 administered intralesionally also slowed papilloma growth. Treated lesions had significantly higher numbers of heterophils and eosinophils.

Acute effects of intravenously administered hypertonic saline solution on transruminal rehydration in dairy cows.

OBJECTIVE: To determine the effect of IV administered hypertonic saline solution (HSS) on transruminal rehydration in clinically normal dairy cows. ANIMALS: 10 Holstein cows. PROCEDURE: Cows in a 2-way randomized cross-over design study were given nothing per os for 36 hours, then were randomly assigned to receive either an oral water load (OWL; 40 ml/kg of body weight) by ruminal gavage or HSS IV (5 ml/kg of body weight) plus OWL; 10 days later, each cow received the other treatment. Outcome measures included serum and urine osmolality, electrolyte (Ca, P, Na, K, and Cl), creatinine, blood glucose, hemoglobin (Hgb), and plasma total protein (PTP) concentrations; serum colloid osmotic pressure (SCOP); urine volume; PCV; and blood gas analytes (pH, P(CO2), P(O2), HCO3-, base excess [BE], and O2 saturation). RESULTS: IV administered HSS plus OWL caused Hgb, PCV, PTP, SCOP, blood pH, BE, HCO3-, and urine osmolality values to decrease and fractional excretion (FE) of electrolytes, serum osmolality, and urine volume to increase. Blood glucose concentration was different between treatments at 0 and 150 minutes, and FEK, FECl, and FECa were similar by 180 minutes after OWL alone, but absolute excretion of Na and P and FENa and FE(P) remained high after HSS administration. Oral water load caused Hgb, PCV, PTP, serum electrolyte and creatinine, SCOP, and urine osmolality values to remain unchanged or decrease slowly and pH, BE, HCO3-, FECa values to increase slightly by 180 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: IV administration of HSS plus OWL, unlike OWL alone, increases circulatory volume rapidly, induces slight metabolic acidosis, increases renal perfusion and glomerular filtration rate, and effects changes in serum Ca and P homeostasis that may be useful in treating sick dairy cows.

A rapid method for determination of blood glucose concentration in cattle.

OBJECTIVE: To determine an accurate rapid method for determination of blood glucose concentration in cattle under field conditions. DESIGN: Prospective, randomized, controlled trial. ANIMALS: 62 clinically normal Holstein cattle: 34 cows and 28 calves. PROCEDURE: Glucose concentrations in venous blood samples were measured in duplicate using a rapid, dry-slide chemistry technique for determination of blood glucose concentration and a laboratory-based method for determination of plasma glucose concentration. Analyses of variance were used to determine whether the relationship between results of the 2 methods was affected by the status of the animals (cows vs calves) or the PCV of the blood samples. Simple linear regression was performed to determine the correlation between the 2 methods and the slope, intercept, and residual error variance of the relationship between the methods. RESULTS: There as a significant linear relationship between the 2 methods throughout the range of glucose concentrations. Mean difference between results of the 2 methods (results for laboratory-based method - results for rapid method) was 12.95 mg/dl (SD, 7.20 mg/dl). The PCV did not affect the relationship, and there was no difference between results of the 2 methods for cows versus calves. Correlation between means of the duplicative values determined by use of the 2 methods was high (r = 0.9462). CLINICAL IMPLICATIONS: The good correlation between the 2 procedures and the comparable precision estimates (coefficient of variation, 7.17% for laboratory-based method; coefficient of variation, 10.11% for rapid methods) indicates that using the rapid method to measure blood glucose concentration is valid in cows and calves.

Fusobacterium necrophorum and Actinomyces pyogenes associated facial and mandibular abscesses in blue duiker.

Anaerobic and aerobic cultures of facial and mandibular abscesses were made from 12 blue duiker (Cephalophus monticola fusicolor) housed at the Deer and Duiker Research Facility of the Pennsylvania State University (USA). Increases in concentrations of total protein and serum globulin occurred in all cases. Actinomyces pyogenes was isolated from nine animals. Fusobacterium necrophorum was present in eight and Bacteroides sp. was found in seven animals; other genera of isolated bacteria included: Streptococcus (from two animals), Lactobacillus (one), Staphylococcus (one) and Actinomyces (two). Eight (67%) of affected animals were less than or equal to 2 yr of age. Facial soft tissues and mandibles were the tissues most often affected. Tissues within the oral cavity were not affected at the time of presentation. A common finding, not reported in other host species with necrobacillosis, was the presence of nondestructive mandibular proliferation.

Experimental induction of abdominal tympany, abomasitis, and abomasal ulceration by intraruminal inoculation of Clostridium perfringens type A in neonatal calves.

The etiologic role of Clostridum perfringens type A in the acute abdominal syndrome characterized by abomasal and rumen tympany, abomasitis, and abomasal ulceration was investigated in neonatal calves. Eight calves, 4 to 12 days old, were inoculated intraruminally with toxigenic C perfringens type A. Before and after C perfringens inoculation, blood samples were collected from all calves for blood gas and serum biochemical analysis and for determination of serum copper concentration; ruminal fluid was obtained for isolation of C perfringens. Calves were monitored daily for clinical signs of the syndrome and, depending on the severity of clinical signs, they were either euthanatized or redosed within 4 to 7 days. After necropsy, specimens obtained from the abomasum and rumen for macroscopic and microscopic examination and for anaerobic bacteriologic culture were processed in routine manner. Intraruminal inoculation of C perfringens type A into healthy calves induced anorexia, depression, bloat, diarrhea, and in some calves, death. Serum copper concentration was within normal range. Necropsy revealed variable degrees of abomasitis, petechial and ecchymotic hemorrhages, and ulcers (ranging from pinpoint to nearly perforate) in the abomasum. Seven of those calves also had multiple trichobezoars in the rumen. These necropsy findings were not seen in calves (controls) given distilled H2O only. In affected calves, acute abdominal syndrome was unrelated to copper deficiency, and C perfringens type A given intraruminally was able to induce clinical signs similar to those of the naturally acquired disease.

Isolation of Clostridium perfringens from neonatal calves with ruminal and abomasal tympany, abomasitis, and abomasal ulceration.

Eight neonatal calves (2 to 21 days old) with suspected abomasal displacement or intestinal obstruction after acute onset of abdominal tympany, colic, depression, or death were referred to Kansas State University for clinical examination or for necropsy. Results of routine hematologic and serum chemical analyses did not reveal consistent changes. Necropsy revealed abomasal distention, with various degrees of abomasitis, hemorrhage, and ulceration, but did not reveal evidence of displaced abomasum or obstructed intestine. Specimens of ruminal contents collected via stomach tube or at necropsy and abomasal contents collected at necropsy were obtained for anaerobic bacteriologic culture. Clostridium perfringens was isolated from all specimens, and on the basis of toxin neutralization tests in mice, 7 were type A and one was type E. Copper concentrations in serum and tissues were within normal limits. It appeared that the acute abdominal syndrome in these neonatal calves was unrelated to copper deficiency, and that C perfringens, particularly type A, may have had an appreciable contributory role in its pathogenesis.