Isolated fracture of the talus with asymptomatic contralateral talar fissure in two dogs.

CASE HISTORY: Two adult male dogs were separately presented for acute-onset, severe hind limb lameness isolated to the tarsus. There were no prior orthopaedic concerns and there was no significant trauma associated with the onset of lameness in either case. CLINICAL FINDINGS: Pain and effusion of the affected tarsus were found in both cases. Lameness was not responsive to oral analgesia. Radiography was insufficient to fully determine the extent of the damage in the tarsus; the fracture was visible in one case only. CT imaging demonstrated an isolated, lateral, trochlear ridge talar fracture in both cases and contralateral talar abnormalities of comparable location and direction to the fracture. DIAGNOSIS: Isolated lateral trochlear ridge fracture of the talus without significant trauma or concurrent injury. Abnormalities of talus of the contralateral limb were demonstrated on CT imaging. CLINICAL RELEVANCE: A previously unrecognised pathological process may affect the talus of adult dogs that could predispose them to develop fracture of the lateral talar ridge without significant trauma. Further investigations are required to determine the prevalence and risk of fracture associated with this abnormality.Abbreviations: HIF: Humeral intercondylar fissure.

Development of a bilayered living skin construct for clinical applications.

An in vitro construct of human skin (living skin equivalent, LSE) has been engineered using serially passaged human epidermal keratinocytes and human dermal fibroblasts with a matrix of type I collagen. Cells are obtained from neonatal foreskin. LSE is cast, cultured, and shipped in a single culture insert. The size and shape of the insert determines the size and shape of the LSE. The dermal matrix consists of dermal fibroblasts within a condensed collagen lattice. The overlying epidermis is developed at the air-liquid interface to generate a protective cornified layer. Serum was not necessary for development of the epidermis. LSE for graft (Graftskin) has handling characteristics similar to split-thickness skin allowing it to be meshed, stapled, and sutured. LSE was cryopreserved using 65% glycerol an rapid freezing. Viability and in vivo performance on athymic mice were similar to fresh LSE. Cells derived from human eccrine gland were able to invade and form tubules rudimentary appendages may be possible.

Epidermis generated in vitro: practical considerations and applications.

The technology for culture of epidermis is one of the most advanced to date for generation of a tissue in vitro. Cultured epidermis is already used for a number of applications ranging from use as a permanent skin replacement to use as an organotypic culture model for toxicity testing and basic research. While simple epidermal sheets have been grafted successfully, more advanced models for skin replacement consisting of both dermal and epidermal components are in development and being tested in a number of laboratories. One of the most advanced in vitro models is the living skin equivalent, an organotypic model consisting of a collagen lattice contracted and nourished by dermal fibroblasts overlaid with a fully formed epidermis.

Breast sensibility: a neurophysiological appraisal in the normal breast.

This study has provided baseline data of a quantitative neurophysiological appraisal of normal breast sensibility using our current understanding of cutaneous mechanoreceptive function. Test variables, including pressure, low- and high-frequency vibration, static and moving two-point discrimination, temperature, nipple erectibility, and pain, were evaluated in 11 normal volunteers using different coordinates over the nipple, areola, and body of the breast. Definite patterns were established so that the breast could be subdivided into distinct cutaneous areas with differing mechanoreceptive characteristics. The future aim is to broaden the scope of this study with preoperative evaluations in our clinical patients so that appropriate recommendations for future reconstructive breast procedures can be made.

Autocrine and paracrine growth stimulation of cells derived from human skin.

A sensitive serum-free culture system was used to demonstrate that cells derived from normal human skin release soluble mediators which can modulate keratinocyte, melanocyte, and fibroblast growth in vitro. In M199 supplemented with epidermal growth factor, hydrocortisone, insulin, transferrin, triidothyronine, bovine serum albumin, and an extract of bovine hypothalamus, keratinocytes underwent approximately three to five cumulative population doublings (CPD) over a 7-day period. Addition of 20% keratinocyte-conditioned medium more than doubled keratinocyte growth and increased fibroblast growth 25-40% above controls. Dermal fibroblasts maintained in the same serum-free hormone-supplemented medium (SFHSM) alone underwent approximately 4.5-5.5 CPD over a 7-day period; 20% fibroblast-conditioned medium increased fibroblast growth 50-80% and increased keratinocyte growth 30-50%. Melanocytes maintained in the same SFHSM underwent approximately 1 CPD over a 14-day period and 2 CPD if the medium was supplemented with 2% fetal bovine serum (FBS). Addition of 20% melanocyte-conditioned medium more than doubled melanocyte growth in either SFHSM or in medium containing 2% FBS, but decreased both keratinocyte and fibroblast growth up to 30-60%. None of the conditioned media altered cellular morphology. These data provide the first demonstration of mutual growth modulation by cell types normally contiguous in vivo and expand existing evidence for autocrine and paracrine growth regulation by normal human cells.

Heterokaryon analysis of the genetic control of pigment synthesis in chick embryo melanocytes.

The genetic control of pigmentation was analyzed using five unlinked mutants, namely, c, pk, Bl, ev and l. Each mutant blocks or reduces pigmentation. Chick melanocyte cultures of each mutant type were fused to produce all ten possible pair combinations of nondividing heterokaryons. Heterokaryons were identified autoradiographically (One partner in each pair was labeled with 3H-thymidine.) Crosses produced comparable pairs of double heterozygotes that were analyzed in vivo and in vitro. Heterokaryon pairs were compared to their corresponding double heterozygotes.--Some combinations showed complementation and produced wild-type pigment. Others showed noncomplementation having little or no pigment. Double heterozygotes complemented each other except in the cases involving the dominant mutant, l. Four heterokaryon pairs gave different results from their corresponding double heterozygotes. The pk-Bl and pk-ev combinations failed to complement as heterokaryons but did complement as double heterozygotes. On the other hand the l-c and I-Bl combinations complemented as heterokaryons but not as double heterozygotes. Based on these differences it is hypothesized that the pk and I loci are nuclearly restricted regulatory elements. Examples in the literature from other systems are cited to support such a hypothesis.

Efficiency and safety of an inactivated feline parvovirus vaccine against canine parvovirus infection.

Inactivated feline parvovirus vaccine produced in a continuous feline cell line evoked a protective canine parvovirus antibody titer and prevented virus shedding following challenge in previously seronegative puppies. Post-vaccinal reactions to the vaccine were not observed in laboratory puppies vaccinated with multiple doses of vaccine or in vaccinated puppies from 5 clinics and/or animal shelters.

Complementation and noncomplementation in heterokaryons of three unlinked pigment mutants of the fowl.

This study shows that melanocyte heterokaryons formed between cells of the blue and recessive white genotypes complement one another to produce normal pigmentation, while heterokaryons of the blue and pinkeye genotypes fail to complement. The simplest interpretation of these findings is that the blue and recessive white mutations affect different aspects of pigment synthesis so that when both kinds of nuclei exist in the same cytoplasm, they can correct (complement) each other's defect. On the other hand, the blue and pinkeye mutations, although unlinked, apparently affect the same aspect of pigment synthesis so that when both kinds of nuclei are in a common cytoplasm, they cannot correct each other's defect. This suggests that one of these two loci exerts some kind of control, or "regulation," over the other. It has previously been shown that recessive white--pinkeye heterokaryons can complement. Thus, only two heterokaryon complementation groups are evident within the three mutants examined.

Evaluation of a bovine virus diarrhea vaccine.

Singer Strain bovine virus diarrhea (BVD) modified live-virus vaccine, produced in a continuous bovine cell line using equine serum in the growth medium, evoked a high level of serum antibodies and protected against virulent challenge in vaccinated calves. Transmission of vaccinal virus from vaccinated cattle to susceptible controls did not occur when vaccinated and nonvaccinated cattle were kept in constant contact for 23 days. Postvaccinal reactions to the viral vaccine were not observed in vaccinated cattle from 10 feedlots or in cattle vaccinated with multiple doses of the experimental vaccine.