ABSTRACT
A keratinolytic protease, secreted as the major component by a feline clinical isolate of Microsporum canis cultivated in a minimal medium containing cat keratin, was purified by affinity chromatography on bacitracin agarose and gel filtration. The apparent molecular mass of the enzyme was 31.5 kDa and the pI was 11.8. The enzyme was not glycosylated and its first 15 N-terminal amino acids showed numerous similarities with other fungal subtilisins. The optimum pH was around 9 while inactivation of the enzyme was reversible at pH 4, but not at pH 11. The enzyme was stable at 37 degrees C with an apparent optimum temperature around 55 degrees C. PMSF, soybean trypsin inhibitor (SBTI) and chymostatin strongly inhibited the proteinase. The highest affinity (Km of 0.37 mM) and physiological efficiency (k(cat)/Km) were obtained for the synthetic substrate N-Suc-Ala-Ala-Pro-Phe-p-nitroanilide. These results indicate that the keratinase belongs to the subtilisin-like serine protease family. Purified rabbit immunoglobulins G prepared against the keratinase and used in an immunohistochemical test allowed the detection of the keratinase produced by the fungus invading hair structures in naturally infected cats. The in vitro keratinolytic activity of the enzyme and its production in vivo suggest that it may contribute to pathogenicity.
Subject(s)
Cat Diseases/microbiology , Dermatomycoses/veterinary , Microsporum/enzymology , Peptide Hydrolases/isolation & purification , Peptide Hydrolases/metabolism , Amino Acid Sequence , Animals , Cats , Dermatomycoses/microbiology , Electrophoresis, Polyacrylamide Gel , Hydrogen-Ion Concentration , Immunoblotting , Immunohistochemistry , Kinetics , Molecular Sequence Data , Peptide Hydrolases/chemistry , Protease Inhibitors , Rabbits , Skin/microbiology , TemperatureABSTRACT
Description of various affections of the iris which may be treated with argon-laser. The problem of the laser iridectomy in the treatment of glaucoma is illustrated by a histologic study of the evolution of the lesions up to four months after coagulation of rabbit's iris.
Subject(s)
Iris Diseases/surgery , Laser Therapy , Animals , Glaucoma/etiology , Iris Diseases/pathology , Lasers/adverse effects , RabbitsABSTRACT
The destructive effect of nonperforating argon laser coagulations in the brown irides of rabbits was studied with quantitative histological methods. Power, spot size, and exposure time were systematically varied. The lateral and axial extensions of the crater and the denaturation of the adjacent tissue were studied. The main conclusions are: (1) the extent of tissue damage is significantly correlated with power and spot size, though the correlation is not proportional; (2) the lateral extension of the tissue reaction is far more pronounced than the axial extension; (3) increase in exposure time is effective up to 0.2 s, though a further increase up to 0.5 s does not enhance the tissue reaction. It is discussed that for conventionally switched lasers the main determinant for the final extension of the lesion is the density and distribution of the pigment granules within the iris. The radial distribution of the protrusions of the melanocytes in brown irides of the rabbits used in this study favors the lateralization of the tissue reaction. The nonlinearity of the tissue reaction and exposure time might be due to the fact that after initial damage in early phases of irradiation (e.g., up to 50 or 100 ms, the absorbed laser energy is dissipated in already destroyed tissue. Some practical aspects for iridectomy are discussed.
Subject(s)
Iris/pathology , Laser Therapy , Lasers , Animals , Iris/surgery , Iris/ultrastructure , Microscopy, Electron, Scanning , RabbitsSubject(s)
Abnormalities, Multiple , Cataract/genetics , Joint Diseases/genetics , Retinal Detachment/genetics , Child , Humans , Male , SyndromeABSTRACT
We describe a high-performance colorimeter with an electronic bubble gate for use with miniaturized continuous-flow analyzers. The colorimeter has a flow-through cuvette with optically flat quartz windows that allows a bubbled stream to pass freely without any breakup or retention of bubbles. The fluid volume in the light path is only 1.8 mul. The electronic bubble gate selectively removes that portion of the photodector signal produced by the air bubbles passing through the flow cell and allows that portion of the signal attributable to the fluid segment to pass to the recorder. The colorimeter is easy to use, rugged, inexpensive, and requires minimal adjustments.
