Myoplasmic calcium regulation in myotubes from horses with recurrent exertional rhabdomyolysis

OBJECTIVE: To determine whether alterations in myoplasmic calcium regulation can be identified in muscle cell cultures (myotubes) and intact muscle fiber bundles derived from Thoroughbreds affected with recurrent exertional rhabdomyolysis (RER). ANIMALS: 6 related Thoroughbreds with RER and 8 clinically normal (control) Thoroughbred or crossbred horses. PROCEDURES: Myotube cell cultures were grown from satellite cells obtained from muscle biopsy specimens of RER-affected and control horses. Fura-2 fluorescence was used to measure resting myoplasmic calcium concentration as well as caffeine- and 4-chloro-m-cresol (4-CMC)-induced increases in myoplasmic calcium. In addition, intact intercostal muscle fiber bundles were prepared from both types of horses, and their sensitivities to caffeine- and 4-CMC-induced contractures were determined. RESULTS: Myotubes of RER-affected and control horses had identical resting myoplasmic calcium concentrations. Myotubes from RER-affected horses had significantly higher myoplasmic calcium concentrations than myotubes from control horses following the addition of > or = 2mM caffeine; however, there was no difference in their response to 4-CMC (> or = 1 mM). Caffeine contracture thresholds for RER and control intact muscle cell bundles (2 vs 10mM, respectively) were significantly different, but 4-CMC contracture thresholds of muscle bundles from RER-affected and control horses (500 microM) did not differ. CONCLUSIONS AND CLINICAL RELEVANCE: An increase in caffeine sensitivity of muscle cells derived from a family of related RER-affected horses was detected in vitro by use of cell culture with calcium imaging and by use of fiber bundle contractility techniques. An alteration in muscle cell calcium regulation is a primary factor in the cause of this heritable myopathy.     

Enzyme-linked immunosorbent assay for screening the plasma residues of tetracycline antibiotics in pigs.

The recommended therapeutic doses of three kinds of tetracyclines, oxytetracycline (OTC, withdrawal period, 10 days), chlortetracycline (CTC, withdrawal period, 5 days) and tetracycline (TC, withdrawal period, 5 days), were each administered to a group of 15 pigs. Blood was sampled before drug administration and during the withdrawal period. The concentration of tetracyclines in plasma, determined by semi-quantitative ELISA, was compared with that of internal standard (10 ppb as oxytetracycline). The absorbance ratio of internal standard to sample (B/Bs) was employed as an index to determine the tissue residues in pigs. All 45 plasma samples from nontreated pigs showed negative in the residue of any of three tetracycline antibiotics. OTC was detected in plasma of pigs treated until the 8th day, CTC until the 4th day, and TC was detected until the 3rd day of its withdrawal period. The present study showed that the semi-quantitative ELISA easily be adopted in predicting tissue residues for tetracycline antibiotics in live pigs.     

Antiviral effect of dietary germanium biotite supplementation in pigs experimentally infected with porcine reproductive and respiratory syndrome virus

Germanium biotite (GB) is an aluminosilicate mineral containing 36 ppm germanium. The present study was conducted to better understand the effects of GB on immune responses in a mouse model, and to demonstrate the clearance effects of this mineral against Porcine reproductive and respiratory syndrome virus (PRRSV) in experimentally infected pigs as an initial step towards the development of a feed supplement that would promote immune activity and help prevent diseases. In the mouse model, dietary supplementation with GB enhanced concanavalin A (ConA)-induced lymphocyte proliferation and increased the percentage of CD3+CD8+ T lymphocytes. In pigs experimentally infected with PRRSV, viral titers in lungs and lymphoid tissues from the GB-fed group were significantly decreased compared to those of the control group 12 days post-infection. Corresponding histopathological analyses demonstrated that GB-fed pigs displayed less severe pathological changes associated with PRRSV infection compared to the control group, indicating that GB promotes PRRSV clearance. These antiviral effects in pigs may be related to the ability of GB to increase CD3+CD8+ T lymphocyte production observed in the mice. Hence, this mineral may be an effective feed supplement for increasing immune activity and preventing disease.     

Antimicrobial-induced endotoxin and cytokine activity in an in vitro model of septicemia in foals

OBJECTIVE: To determine which antimicrobials that are used to treat neonatal foals with septicemia attributable to Escherichia coli will minimize endotoxin release from bacteria and subsequent activity of inflammatory mediators while maintaining bactericidal efficacy. SAMPLE POPULATION: Blood samples from 10 healthy foals. PROCEDURE: Escherichia coli isolates A and B were isolated from 2 septicemic foals, and minimal inhibitory concentrations (MIC) were determined for 9 antimicrobials. Five of these antimicrobials were tested in vitro at 2 and 20 times their respective MIC. Whole blood or mononuclear cells grown in tissue-culture media were incubated with 105 colony-forming units of E. coli and each antimicrobial or saline (0.9% NaCl) solution. After 6 hours, number of viable bacteria remaining was determined, and supernatant was tested for endotoxin and tumor necrosis activity. RESULTS: Testing in whole blood was compromised by bactericidal effects of the blood itself. In mononuclear cell suspensions, each antimicrobial significantly reduced the number of viable bacteria to low or undetectable amounts. Antimicrobials did not differ significantly in efficacy of bacterial killing. Amikacin used alone or in combination with ampicillin resulted in significantly less endotoxin activity than did ampicillin, imipenem, or ceftiofur alone. There was a correlation between TNF-alpha and endotoxin activity. CONCLUSIONS AND CLINICAL RELEVANCE: Aminoglycosides appear less likely to induce endotoxemia and TNF-alpha synthesis during bactericidal treatment of E. coli septicemia, compared with beta-lactam antimicrobials. Use of ampicillin, imipenem, or ceftiofur in the treatment of septicemic neonatal foals should be accompanied by appropriate treatment for endotoxemia.     

Genetic analysis of ORF5 of recent Korean porcine reproductive and respiratory syndrome viruses (PRRSVs) in viremic sera collected from MLV-vaccinating or non-vaccinating farms

The 23 open reading frame (ORF) 5 sequences of Korean type II porcine reproductive and respiratory syndrome virus (PRRSV) were collected from viremic sera from the (modified live vaccine) MLV-vaccinating and non-vaccinating farms from 2007 to 2008. The samples were phylogenetically analyzed with previous ORF5 sequences, including type I Korean PRRSV, and previously reported or collected sequences from 1997 to 2008. A MN184-like subgroup of type II Korean PRRSV was newly identified in the viremic sera collected from 2007 to 2008. And of the type I PRRSVs, one subgroup had 87.2~88.9% similarity with the Lelystad virus, showing a close relationship with the 27~2003 strain of Spain. The maximum parsimony tree of type II PRRSV from 1997 to 2008 showed that they had evolved to four lineages, subgroups 1, 2, 3 and 4. Most of the recently collected type II PRRSVs belonged to subgroup 4 (48%). The region of three B-cell epitopes and two T-cell epitopes of ORF5 amino acids sequences was considerably different from the MLV in subgroups 3 and 4. In conclusion, the existence of type I PRRSV, which was genetically different from Lelystad virus (Prototype of type I PRRSV), and heterologous type II PRRSVs of viremic pigs detected even in the MLV-vaccinating farms indicated the need for new vaccine approaches for the control of PRRSV in Korea.     

Evaluation of canine gastric motility with ultrasonography

For the evaluation of canine gastric motility with ultrasonography, contraction number of pyloric antrum and gastric emptying time (GET) by area and volume method developed by Bolondi et al.'s method were studied in 14 dogs. All experimental dogs were administered with saline and soup solution (10 ml/kg, B.W.). The mean values of contraction number of pyloric antrum in saline and soup group were 4.19 +/- 1.30/min and 4.82 +/- 0.65/min before feeding, and overall mean values were 4.66 +/- 1.37/min and 5.13 +/- 1.71/min, respectively. The mean values of the GET by area and volume method were 36.73 +/- 11.27, 40.00 +/- 8.87 min in saline group and 61.35 +/- 17.58, 59.11 +/- 14.46 min in soup group. In the GET in saline and soup groups, there was no significant difference between the area and volume method (p>0.05). Therefore, Bolondi et al.'s method by ultrasound can be used to evaluate the antropyloric motility and gastric emptying time with area and volume methods. The area method is easier to determine the GET than the volume method, but the latter is more accurate.     

Relationship of pre- and post-ovulatory gonadotropin concentrations to subnormal luteal function in postpartum beef cattle

Early weaning of calves from anestrous cows results in formation of short-lived corpora lutea (CL) unless the animals are pretreated with a progestagen (norgestomet). This study was conducted to investigate the relationship between pre- and post-ovulatory gonadotropin secretion and luteal lifespan. Postpartum beef cows were assigned randomly into two groups, control (n = 5) and norgestomet (implant given at weaning for 9 d; n = 7). Calves from all cows were weaned 30 to 33 d postpartum. Coccygeal artery cannulas were placed into cows in the control group 1 d prior to weaning and 2 d before implant removal in cows in the norgestomet group. Plasma for determination of luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol-17 beta (E) and progesterone (P) was collected daily at 10-min intervals for 6 h from weaning (control) or the day prior to implant removal (norgestomet) to estrus (d 0) and on d 2, 4 and 6 following estrus. Average interval (X +/- SE; P less than .05) from weaning to estrus or implant removal was 4.2 +/- .8 and 2.3 +/- .2 d for the control and norgestomet groups, respectively. Estrous cycle length for the control group was 12.4 +/- 1.8 d compared with 20.4 +/- .3 d for the norgestomet group (P less than .05). Four of five control cows had an estrous cycle length of 7 to 14 d; all cows in the norgestomet group and the remaining control cow had an estrous cycle of normal length (16 to 21 d).2+ estrus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Perianesthetic development of diaphragmatic hernia in a horse with equine pituitary pars intermedia dysfunction (PPID)

A 21-year-old Thoroughbred gelding with a history of equine pituitary pars intermedia dysfunction (PPID) presented with priapism of 2 days’ duration. The horse received a caudal morphine epidural and then underwent corpus cavernosum lavage and phallectomy under general anesthesia. The patient’s recovery featured multiple unsuccessful attempts to stand and his respiratory distress persisted for several hours until he acutely developed severe colic and was euthanized. Necropsy findings revealed a pituitary adenoma of the pars intermedia, bilateral adrenal cortical hyperplasia, and diaphragmatic herniation. This report suggests that horses with PPID may present a greater risk for diaphragmatic hernia under general anesthesia or during procedures placing stress on the diaphragm, including anesthetic recovery.