Forestomach papillomas in flaky skin and steel-Dickie mutant mice.

Gastric papillomas were diagnosed in flaky skin (fsn/fsn) and steel-Dickie (Sl/Sld) mutant mice but not littermate controls. Both mutants suffer from severe anemia of differing causes. Immunohistochemical screening and Southern blot analyses failed to detect any evidence of a papillomavirus in the gastric lesions. Phenotypic expression of the fsn and Sld mutant genes may play an essential role in the spontaneous development of forestomach papillomas in these mouse mutants.

Imaging rounds. Synovial chondromatosis.

The following case is presented to illustrate the roentgenographic and clinical findings of a condition of interest to the orthopaedic surgeon. Initial history, physical findings, and roentgenograms are found on the first two pages. The following pages present the final clinical and roentgenographic differential diagnosis.

Turn-on transient statistics and dynamics in a multimode, short-cavity laser.

The statistics of turn-on delay times for a longitudinal mode and the total intensity from a multimode, standing-wave, short-cavity dye laser are measured and compared with numerical simulations of a multimode theory of laser dynamics. Differences between the measurements and the theory for the average and standard deviation of the turn-on time are due to transitory modes that decay as a result of frequency-dependent losses and gains. Associated with this phenomenon is a kink in the time evolution of the mode intensity that represents a transition in the dynamics from domination by independent growth of all modes to domination by competition between modes with differing net gains. This unequal competition increases the average and standard deviation of the mode turn-on time.

"Lipomatous" hamartomas and choristomas in inbred laboratory mice.

In a retrospective study, 37 male and 19 female inbred laboratory mice, from 1 to 36 weeks of age, were diagnosed with "lipomatous" hamartomas or choristomas from nearly 10,000 mice examined at necropsy over a 24-month period. Hamartomas and choristomas were found to be rare, noninherited tumor-like conditions that occurred spontaneously in 18 inbred strains of mice with a predominance of the conditions in the C3H/HeJ and C57BL/6J strains. Prevalence between strains ranged from 0.6 to 6.2 cases per hundred thousand mice. The 56 cases studied had soft, raised masses that arose on the dorsal midline, primarily above the sutures of the skull. The lesions were prominent on gross examination due to abnormally long hair, change in direction of the hairs, and a change in hair color compared to the normal pelage. Microscopically, the masses consisted of normal adipose tissue in the reticular dermis and subcutis that sometimes extended through the cranial sutures, entering the brain, or expanding into the ventricles. Large masses occasionally contained normal appearing thyroid, intestine, respiratory epithelium lined cysts, squamous epithelial cysts, bone and marrow, cartilage, glands, and angiomatous anomalies. In all cases, the epidermis was intact. Hair follicles were larger in the affected areas of many cases compared to those in adjacent skin. Breeding studies did not yield affected offspring, indicating this is a congenital, noninherited abnormality. This condition resembles "lipomatous" hamartomas, a congenital defect in human beings.

Skeletal muscle rhabdomyosarcomas in inbred laboratory mice.

A total of 14 well differentiated rhabdomyosarcomas were diagnosed at necropsy in 10,000 mice. Of the 14 affected mice, ten were BALB/cJ, and there was one case each of A/HeJ, BALB/cByJ, C58/J, and C.B-17-scid/scid strains. Most often (10/14) tumors originated in the quadriceps muscles and metastases occurred in six cases. When submitted, affected mice were 2 to 8 months of age, with a mean age of 4 months. Tumor frequency for BALB/cJ mice was calculated to be 2.4/100,000 mice retained as breeders. No sexual dimorphisms were determined when data were correlated to actual numbers of each sex in the colony. All 14 primary tumors and metastases were positive by immunohistochemistry for the proteins pan myosin, sarcomeric actin, desmin, actin, and myosin, but were negative for smooth muscle actin, thus confirming the diagnosis. Using cell free homogenates of primary tumors, inoculated by intraperitoneal or intramuscular injection, tumors were not induced in either BALB/cJ or C58/J mice observed over a 22-week period. Southern blot analysis of DNA prepared from tumors and hybridized with a murine leukemia virus probe that recognizes both ecotropic and dualtropic viruses did not demonstrate viral genomic fragments in addition to those known to occur in each strain.

Anatomical variations in the course of the superficial peroneal nerve.

Eighty-five legs in forty-four cadavera were dissected to determine the course of the superficial peroneal nerve from its origin to its termination as dorsal cutaneous nerves of the foot. Particular attention was paid to the relationship of the nerve with the intermuscular septum between the anterior and lateral compartments of the leg. In sixty-two (73 per cent) of the legs, the nerve coursed within the lateral muscle compartment from its origin to its exit through the crural fascia. In twelve (14 per cent) of the legs, the nerve had a variable course in the lateral compartment, crossed into the anterior compartment, and passed through the fascia. In ten (12 per cent) of the legs, the nerve divided in two, with branches in both the anterior and the lateral compartment. In one leg, the nerve never lay deep to the peroneus longus but ran along the deep surface of the fascia before exiting distally. The nerve or its branches passed through the fascia three to eighteen centimeters proximal to the lateral malleolus.

Papillomavirus infection of aged Persian cats.

Papillomavirus infection was confirmed in 2 Persian cats with sessile hyperkeratotic skin lesions. Skin lesions were not typical papillomas as found in other species. Papillomavirus were demonstrated in negative stain preparations of homogenized tissue and within nuclei of cells in the stratum granulosum. Papillomavirus group-specific antigens were detected within nuclei corresponding to those containing virions. Attempts to transmit this disease to other cats or propagate the virus in tissue cultures were unsuccessful. A 7.8-kilobase DNA molecule was present in low-stringency Southern blots using a bovine papillomavirus type 1 cloned DNA probe. In reverse Southern blots, the cat papillomavirus hybridized under conditions of low stringency with all papillomavirus genomes tested. Combined with limited restriction endonuclease restriction mapping, the above information indicates that the feline cutaneous papillomavirus is a unique virus type and thus expands the list of hosts known to be infected by papillomaviruses.