Comparative study of hair follicle morphology in eight mammalian species and humans.

BACKGROUND: The objective of the present study was the investigation of hair follicle morphology in eight mammalian species in order to evaluate the species-specific contribution of hair follicles to skin penetration particularly with regard to the utilization of the different animal species as skin models for human skin. METHODS: Cyanoacrylate skin surface biopsy method (CSSB), light microscopy and also digital photography were used for the measurements of hair follicle morphology. RESULTS: The results revealed species-specific differences regarding the pattern of hair follicle distribution and also differences with regard to hair follicle parameters and characteristics. The results also showed that hair follicles generally possess enormous reservoir capacities, regarding the follicular volume. In all examined species, hair follicles reached at least one-fifth of stratum corneum storage capacity. The results were compared with human data obtained in a previous study. CONCLUSION: With regard to hair follicle morphology and skin structure, the porcine skin seems to be the most appropriate skin model for human skin analog to previous investigations, whereas the skin of dog, cat, and rabbit showed the most significant differences.

Serial serum feline pancreatic lipase immunoreactivity concentrations and prognostic variables in 33 cats with pancreatitis.

OBJECTIVE: To identify factors significantly associated with prognosis in cats hospitalized because of pancreatitis. DESIGN: Prospective case series. Animals-33 cats hospitalized for treatment of pancreatitis (diagnosis determined on the basis of clinical signs and serum feline pancreatic lipase immunoreactivity [fPLI] concentration ≥ 5.4 µg/L). PROCEDURES: Cats were hospitalized (day 1) for 2 to 16 days and observed for 44 days or until they died or were euthanized. Results of physical examination and hematologic and serum biochemical analysis, including measurement of serum fPLI concentration, performed on the day of hospital admission were analyzed to determine whether they were associated with outcome (ie, survival to at least 44 days vs death or euthanasia). RESULTS: On day 1, mean × SD serum fPLI concentration among the 33 cats was 22.0 × 16.4 µg/L. Mean age of the cats was 12.7 × 3.8 years (range, 4 to 19 years). Eleven of the 33 (33%) cats died or were euthanized before day 44. In univariate analyses, dyspnea, hypothermia, hypokalemia, hyperkalemia, and serum fPLI concentration were significantly associated with an adverse outcome. However, in a multivariate analysis, only severe dyspnea, hyperkalemia (potassium concentration > 5.5 mmol/L), and serum fPLI concentration at the time of hospital admission were found to be significantly associated with an adverse outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that dyspnea, hyperkalemia, and serum fPLI concentration at the time of hospital admission were significant prognostic factors for cats hospitalized because of pancreatitis.

Porcine ear skin: an in vitro model for human skin.

BACKGROUND/PURPOSE: Porcine ear skin is used in studies of percutaneous penetration as a substitute for human skin. The structure of this tissue, including hair follicles, was studied qualitatively and quantitatively in comparison with human skin. METHODS: Sections of shock-frozen biopsies, biopsies embedded in paraffin and cyanoacrylate skin surface biopsies were investigated using microscopy. The thickness of the different skin layers and the follicular characteristics were determined. RESULTS: The thickness of the stratum corneum was 17-28 microm, whereas the viable epidermis was 60-85 microm thick. On 1 cm(2), 11-25 hairs were detected, showing a diameter of 58-97 microm and a maximal extension depth of 0.96-1.38 mm into the skin. The orifices of the porcine infundibula showed a diameter of approximately 200 microm. CONCLUSIONS: The results obtained are similar to those of human skin, indicating the suitability of this porcine tissue as a model for human skin.