Risk factors affecting the outcome of surgery for atlantoaxial subluxation in dogs: 46 cases (1978-1998)

OBJECTIVE: To identify risk factors for successful surgical management of dogs with atlantoaxial subluxation (AAS). DESIGN: Retrospective study. ANIMALS: 46 dogs managed surgically for AAS. PROCEDURE: Age at onset of clinical abnormalities, duration of clinical abnormalities prior to surgery, radiographic appearance of the dens, type (dorsal or ventral procedure) and number (1 or 2) of surgeries performed, grade of postoperative atlantoaxial joint reduction, and neurologic status prior to surgery (preoperative), when dogs were discharged from the hospital (postoperative), and during a follow-up evaluation (final) were obtained from the dogs' medical records. Risk factors for surgical success and degree of neurologic improvement were identified and analyzed for predictive potential. RESULTS: Age at onset of clinical abnormalities < or = 24 months was significantly associated with greater odds of a successful first surgery and final outcome and a lower postoperative neurologic grade. Duration of clinical abnormalities < or = 10 months was significantly associated with greater odds of a successful final outcome and a lower final neurologic grade. A preoperative neurologic grade of 1 or 2 was significantly associated with a lower final neurologic grade. Potential risk factors that did not affect odds of a successful outcome included type of surgery performed, grade of atlantoaxial joint reduction, radiographic appearance of the dens, or need for a second surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Age at onset of clinical abnormalities, duration of clinical abnormalities prior to surgery, and preoperative neurologic status are risk factors for success of surgical management of AAS in dogs.     

The application of ultraviolet microscopy to the distribution of lignin in wood description and validity of the technique

A method has been developed for the determination of lignin distribution in the wood cell wall by ultraviolet microscopy. The method incorporates some important advances on previus applications of UV microscopy to the study of lignin distribution. Ultrathin cross-sections of wood are obtained by the sample preparation and sectioning techniques of electron microscopy. The specimens are examined in monochromatic ultraviolet light using quartz reflection optics. The microscope image is photographically recorded and the negative is subsequently subjected to densitometric analysis. Each stage of the analytical procedure has been critically assessed to determine its validity and limitations. The method is ideally suited to the study of the removal of lignin from the wood cell wall during cooking and possesses other important applications in wood technology.     

Chemical characterization of tissue fractions from the middle lamella and secondary wall of black spruce tracheids

Summary Elemental and functional group analyses were carried out on tissue fractions from the secondary wall and middle lamella of black spruce tracheids. The secondary wall lignin was found to contain 1.7 times as much methoxyl per C₉ as the middle lamella lignin, indicating a substantial proportion of unmethylated para-hydroxyphenylpropane residues in the middle lamella. The content of carbonyl groups was at least three times larger in middle lamella lignin than in secondary wall lignin. The carboxyl content of the middle lamella was found to be about three times as large as that of the secondary wall. Elemental analyses show a higher carbon and lower oxygen content in the middle lamella than in the secondary wall.     

Surgical treatment of perforating duodenal ulcer in a dog by use of modified choledochoduodenostomy and gastrojejunostomy

Modified choledochoduodenostomy and gastrojejunostomy were used successfully to treat extensive duodenal ulceration and perforation in a dog. Concomitant pyometra, simultaneously managed by ovariohysterectomy, may have predisposed the dog to stress ulceration. Choledochoduodenostomy was performed by transplantation of the entire common bile duct and associated major duodenal papilla to a more distal duodenal location. An indwelling choledochostomy tube was used to stent the anastomotic site, externally divert bile flow, and allow postoperative cholangiography. Early postoperative complications included presumed metronidazole-induced neurotoxicosis, choledochostomy tube obstruction, and pancreatitis, all of which resolved within 2 weeks. The dog was clinically normal and medication (ranitidine and sucralfate) was discontinued 35 months later.     

In situ detection of beta-galactosidase in lenses of transgenic mice with a gamma-crystallin/lacZ gene

Transgenic mice carrying the gamma 2-crystallin promoter fused to the coding region of the bacterial lacZ gene were generated. The offspring of three founder mice expressed high levels of the enzyme solely in the central nuclear fiber cells of the lens as measured by an in situ assay for the detection of beta-galactosidase activity. These results suggest that gamma 2-crystallin sequences between -759 to +45 contain essential information required for appropriate tissue-specific and temporal regulation of the mouse gamma 2-crystallin gene. In a broader context, this study also demonstrates the utility of beta-galactosidase hybrid gene constructs for monitoring the activity of gene regulatory elements in transgenic mice.     

A breakdown of Brassica self-incompatibility in ARC1 antisense transgenic plants

Self-incompatibility, the rejection of self pollen, is the most widespread mechanism by which flowering plants prevent inbreeding. In Brassica, the S receptor kinase (SRK) has been implicated in the self-incompatibility response, but the molecular mechanisms involving SRK are unknown. One putative downstream effector for SRK is ARC1, a protein that binds to the SRK kinase domain. Here it is shown that suppression of ARC1 messenger RNA levels in the self-incompatible Brassica napus W1 line is correlated with a partial breakdown of self-incompatibility, resulting in seed production. This provides strong evidence that ARC1 is a positive effector of the Brassica self-incompatibility response.     

Subtotal colectomy for treatment of acquired megacolon in the dog and cat

The case records of 4 cats and 1 dog with megacolon and constipation were reviewed to study the history, clinical signs, pathologic changes, and longterm results of surgical treatment. The 4 cats had idiopathic megacolon. The dog had megacolon secondary to dietary indiscretion. All animals had radiographic evidence of a large colon, which was confirmed by exploratory coeliotomy. Two of the cats and the dog had an intraoperative finding of megacecum as well. Subtotal colectomy was performed in all cases, with the ileocolic valve being removed in 3 of these cases. End-to-side anastomosis was used to restore the integrity of the bowel. All animals were treated successfully with this surgical technique, as judged by clinical response and owner satisfaction. Histologically, there were no consistent lesions to explain the cause of this disease in the cats.