1. Incubation of NADH-ubiquinone oxidoreductase (Complex I) with chymotrypsin caused loss of rotenone-sensitive ubiquinone-1 reduction and an increase in rotenone-insensitive ubiquinone reduction. 2. Within the same time-course, NADH-K(3)Fe(CN)(6) oxidoreductase activity was unaffected. 3. Mixing of chymotrypsin-treated Complex I with Complex III did not give rise to NADH-cytochrome c oxidoreductase activity. 4. Gel electrophoresis in the presence of sodium dodecyl sulphate revealed selective degradation of several constituent polypeptides by chymotrypsin. 5. With higher chymotrypsin concentrations and longer incubation times, a decrease in NADH-K(3)Fe(CN)(6) oxidoreductase was observed. The kinetics of this decrease correlated with solubilization of the low-molecular-weight type-II NADH dehydrogenase (subunit mol.wts. 53000 and 27000) and with degradation of a polypeptide of mol.wt. 30000. 6. Phospholipid-depleted Complex I was more rapidly degraded by chymotrypsin. Specifically, a subunit of mol.wt. 75000, resistant to chymotrypsin in untreated Complex I, was degraded in phospholipid-depleted Complex I. In addition, the 30000-mol.wt. polypeptide was also more rapidly digested, correlating with an increased rate of transformation to type II NADH dehydrogenase.

No abstract

The prevalence of oronasal and oroantral fistulas (ONF/OAF) was retrospectively identified in a population of dachshund patients (dachshund group) and was compared to a population of small breed dogs of significantly similar age and weight (control group). When compared with the control group, the dachshund group was significantly more likely to have an ONF/OAF ( P < .0001). The odds ratio indicates that dachshunds were 3.3 times more likely to have an ONF/OAF than individuals within the control group. This study statistically confirms previous reports and clinical observations that dachshunds are predisposed to ONF/OAFs. When ONF/OAFs are present, the maxillary canines are the most commonly affected dentition in both study groups.