Simultaneous identification of two cyclohexanone oxidation genes from an environmental Brevibacterium isolate using mRNA differential display.

The technique of mRNA differential display was used to identify simultaneously two metabolic genes involved in the degradation of cyclohexanone in a new halotolerant Brevibacterium environmental isolate. In a strategy based only on the knowledge that cyclohexanone oxidation was inducible in this strain, the mRNA population of cells exposed to cyclohexanone was compared to that of control cells using reverse transcription-PCR reactions primed with a collection of 81 arbitrary oligonucleotides. Three DNA fragments encoding segments of flavin monooxygenases were isolated with this technique, leading to the identification of the genes of two distinct cyclohexanone monooxygenases, the enzymes responsible for the oxidation of cyclohexanone. Each monooxygenase was expressed in Escherichia coli and characterized. This work validates the application of mRNA differential display for the discovery of new microbial metabolic genes.

Comparison of two pre-surgical skin preparation techniques.

A one-step iodophor skin preparation solution was compared to chlorhexidine gluconate application as a pre-operative skin preparation method in 100 animals undergoing elective ovariohysterectomy. Pre-operative and intra-operative skin cultures demonstrated no difference in antiseptic efficacy. No animal in the study demonstrated signs of systemic infection, and no adverse local effects from either antiseptic were seen. The iodophor solution evaluated (DuraPrep) is a safe and effective pre-operative skin preparation agent in small animal patients undergoing clean surgical procedures.

Cerebral control of saccades and neuropsychological test results after head injury.

Abnormalities in the control of saccades have been described in patients with cerebral pathology.(1, 2) We assessed control of visually guided, reflexive and volitional saccades in 16 patients suffering severe traumatic brain injury and 12 controls and related the results to deficits on neuropsychological tests of speed of information processing and goal directed behaviour. All saccadic latencies were prolonged. Suppression of inappropriate saccades was impaired on volitional saccade tests which proved to be more sensitive in identifying impairment of goal directed behaviour than the neuropsychological test results. Patients' self-paced saccade rate was lower than controls' and correlated with performance on several visually mediated neuropsychological test results. Patients' visually guided, reflexive saccades were hypometric; this hypometria correlated with both visual and non-visual neuropsychological test results and with post-traumatic amnesia duration. Hypometria in reflexive saccades may reflect diffuse brain injury. Re-examination after 12 months revealed that the control of volitional saccades improved but there was no improvement in the visually guided reflexive saccade measures. The volitional saccade tests may be useful in documenting both impairment and subsequent recovery.

Effects of stimulus velocity and acceleration on smooth pursuit in motor neuron disease.

Sinusoidal smooth pursuit eye movements were evaluated in 11 normals, five moderately and four severely affected motor neuron disease (MND) patients, using two target amplitudes and a range of frequencies. This enabled us to examine separately the effects of peak target velocity and acceleration on pursuit gain. Moderately affected patients showed an acceleration, but not a velocity saturation; severely impaired patients' performance declined with increased velocity. Smooth pursuit eye movements are thus impaired in MND, but the nature of this pursuit deficit is complex and changes with the progression of the disease.

Aspirated dental calculus in a dog.

Aspiration of a dental calculus, with lodgement of the calculus in a mainstem bronchus, was identified in a dog after dental prophylaxis. The calculus was located by use of radiography and bronchoscopy, and was removed via thoracotomy. Aspiration is a possible complication of dental prophylaxis. Endotracheal intubation with a properly inflated cuff, and thoroughly rinsing the oral cavity after prophylaxis, may avoid this and similar complications.

Predictors of decline in Alzheimer's disease.

Age of onset and aphasia are frequently proposed as predictors of decline in Alzheimer's disease (AD). We compared longitudinally the neuropsychological test performance of AD patients classified as Fast Decliners (FD, N = 18) based on the rate of change of their scores on the Mini-Mental State Examination (MMS) and a group classified as Slow Decliners (SD, N = 15). There was no statistical difference in the age of onset of AD or in severity of dementia at first visit. Performance on verbal tests was the best predictor of rapid cognitive decline, even after the influence of the overall degree of dementia had been accounted for. Among the language tasks, performance on a naming test was the best predictor. The results of this study do not support age of onset as a predictor of the course of AD. On the other hand, poor performance on language tests does predict a more rapid rate of decline in AD.

Femoral capital physeal fractures in dogs: 34 cases (1979-1989).

Complications associated with femoral capital physeal (CP) fractures in 34 dogs were evaluated. Fractures were surgically repaired, using divergent K-wires or lag screws; radiographic follow-up was available for 21 CP fractures. In all cases, radiographic abnormalities such as degenerative joint disease and resorption of the femoral neck and/or head were seen. Changes were more severe when fracture occurred at an early age. For 4 of 21 dogs (20%), femoral head and neck excision was performed because of complications associated with CP fracture repair. Prognosis for femoral CP fractures is guarded, although affected dogs should be able to function as pets.

Comparison of nerve regeneration through different types of neural prostheses.

Rat sciatic nerve regeneration through three synthetic neural prostheses was compared with regeneration through nerve allografts. The synthetic prostheses were either nonpermeable nonabsorbable (Silastic), permeable absorbable (polyglactin mesh), or permeable nonabsorbable (polypropylene mesh). Animals were evaluated at 10, 24, and 90 days. Functional analysis of nerve regeneration was performed by noninvasive methods: electromyography and walking tracks. Nerve tissue was examined with routine histologic and immunofluorescent techniques. A compressive neuropathy developed with the use of the Silastic implant. A neutrophilic inflammatory infiltrate was consistently associated with implantation of the polyglactin mesh. A strong connective tissue response was noted around the polypropylene mesh. Early recovery of nerve function was seen with the Silastic implants, however, overall nerve function was best in the nerve allograft and polypropylene mesh groups. Polyglactin implantation increases the local inflammatory response and should not be used for nerve anastomoses. If Silastic entubulation is used, it should be removed between 24 and 90 days.

Use of external coaptation for the treatment of avascular necrosis of the femoral head in a dog.

Avascular necrosis of the femoral head was diagnosed in a 5-month-old Schipperke, before the development of femoral head and neck collapse and resultant degenerative joint disease. External coaptation, consisting of an Ehmer sling, was used to prevent the bearing of weight during revascularization and reossification of the subchondral bone. Results of pelvic radiography (at 10 and 24 weeks) indicated that the early use of conservative treatment was successful in promoting resolution of the aseptic necrosis and in maintaining normal coxofemoral anatomic features and function.

Malignant fibrous histiocytoma in a cat.

A large proliferative soft tissue mass found on the forelimb of an adult cat was identified as a malignant fibrous histiocytoma through cytologic and histologic examinations. This is a rare tumor of mesenchymal cell origin, which has been previously reported in cats, dogs, horses, and human beings. In this cat metastasis to the local lymph node was found.

Comparison of sciatic nerve regeneration through silicone tubes and nerve allografts.

Sciatic nerve regeneration through implanted silicone tubes was compared to allogenic nerve grafting in 30 adult female Sprague-Dawley rats. Regeneration was assessed at 10, 24, and 90 days post-transection. Axonal regrowth through the implanted neural prostheses was evaluated with electromyography and histologic examination.

Normal rates of forgetting of verbal and non-verbal material in Alzheimer's disease.

Recent work has suggested that patients with damage to temporal lobe structures, such as patients with Alzheimer's Disease (AD), lose information from memory at an abnormally rapid rate. In contrast, data from other studies suggest that the rate of forgetting in AD is normal. In the present study, 62 patients with mild to moderate AD and 64 elderly controls were tested for their immediate and delayed recall of a short verbal passage and a modified Rey complex figure. The results suggest that although AD patients recalled less than controls, they did not forget at a faster rate during the 30 minute retention interval, supporting the finding that these memory impaired patients do not have an abnormal rate of forgetting. The data also suggest that poor initial encoding of the stimuli may be the cause of the AD patients' impaired recall.