Isolation of Streptobacillus moniliformis from the middle ear of rats.

Streptobacillus moniliformis was isolated from the middle ear of 9 of 16 rats used for otological studies. Examination of rat sera for the presence of anti-Streptobacillus moniliformis antibodies using an ELISA technique resulted in 15 seropositive animals. The source of the S. moniliformis infection was not determined.

Substitution of the anterior cruciate ligament: a long-term histologic and biomechanical study with autogenous pedicled grafts of the iliotibial band in dogs.

This paper reports the experience with anterior cruciate ligament (ACL) substitution by standardized pedicled strips of the iliotibial band, fixed to the tibia and femur with a bone-peg fixation technique. Thirty-two young adult (+/- one year old) Labrador dogs were used for the experiments (58 transplant knees and six controls). The posttransplantation period ranged from day zero to three years postoperatively. Of the transplants, there were five failures. Forty-seven knees served for gross, photographic, and histologic examination. In 17 knees, the transplants were submitted to tensile testing in an Instron testing machine. The behavior of the ACL transplants was as follows: the transplants became necrotic in a short period of time, but after day four, a process of creeping substitution took place. At 12-16 weeks, a newly formed ligament was seen with a striking macroscopic resemblance to the normal ACL. However, its collagen fibers were coarser and more undulant, and they were fixed to the bony interfaces with Sharpey-like fibers. When these rather good-looking ACLs were subjected to mechanical testing and compared with normal ACLs, the results were less satisfactory. Mechanically, the substituted ACLs were 45% less stiff than normal ligaments, the yield point was at one-third, and the ultimate load was 40% of that of a normal ACL (deformation rate, 5 mm/min). Normal ACLs rupture at their tibial insertion. The transplants ruptured intraligamentarily. A striking finding was that the substituted ligament did not derotate when all the other ligamentous and capsular structures were cut. There was no torsional arrangement of their component bundles. Although the substituted ACL has an excellent histological and macroscopic appearance, its mechanical properties are inferior.

Bioreactions at the tissue/hydroxyapatite interface.

The events at the hydroxyapatite implant material/tissue interface in the rat middle ear were studied by light microscopy, autoradiography, morphometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray microanalysis. Deposition of calcium, partially in the form of calcium phosphate, was found at the interface. Resorption of the implant material occurred as the result of mono- and multinuclear phagocyte activity. Resorption decreased 6 mnth after the operation, possibly due to the decreasing number of phagocytes at the interface and the increasing amount of bone in the macropores.

Hearing loss in the cervico-oculo-acoustic (Wildervanck) syndrome.

A 22-year-old woman with mixed hearing loss, Klippel-Feil anomalad (fused cervical vertebrae), and bilateral abducens palsy with retracted bulb (Duane's syndrome) is classified as having the cervico-oculo-acoustic syndrome or Wildervanck syndrome. In this syndrome, the unilateral or bilateral congenital hearing loss is usually severe and of neurosensory origin. To our knowledge, this is the third case of this syndrome with the classical triad and a mixed hearing loss. It is the second case in which an exploratory tympanotomy was performed. An ankylosis of the stapes was found. Stapedectomy and Teflon interposition were successfully carried out. Since the triad of the cervico-oculo-acoustic syndrome can be incomplete, a review of the association of Klippel-Feil anomalad and hearing loss is also presented, with special attention to the anomalies of the ossicular chain.

The effect of ethane-1-hydroxy-1, 1-diphosphonic acid (EHDP) on matrix induced ectopic bone formation.

The effect of diphosphonates (EHDP) was studied on induced ectopic osteoneogenesis. Decalcified allogeneic bone matrix was implanted into the lumbar muscles in rabbits for an ectopic osteoinductor. The ectopic new bone formation was studied under continuous EHDP administration and after discontinuation of EHDP. Although there was no inhibitory effect of EHDP on the osteoinduction, the calcification of the new bone and the resorption of the implanted matrix was retarded. The induced "osteoid-like" tissue had an atypical structure with a small number of cells and a deficiency in collagen fiber bundles. There were also large fields of new cartilage formation. Thus remodelling and mineralization were inhibited under the influence of continuous administration of EHDP. After discontinuation of EHDP administration a recovery phase was observed which seemed to lead to the formation of a normal ossicle.