Quantitative histochemical investigations of semipermeable membrane techniques for the assay of acid phosphatase in skeletal muscle. III. A modified simultaneous coupling technique

Acid phosphatase activity in soleus and plantaris muscle fibres of normal and dystrophic hamsters. A quantitative histochemical study

The activity of acid phosphatase in skeletal muscle fibres of the plantaris and soleus of normal and dystrophic male hamsters was quantified using a histochemical post-coupling semipermeable membrane technique. Although the absolute levels of activity were found to vary widely from one animal to another, the ratio of the mean activities in the two muscles in each animal was virtually constant. In normal muscles, the ratio was about 0.73 and in dystrophic muscles, about 0.77. The activity in plantaris muscle fibres was always significantly lower than that in the corresponding soleus fibres, and in normal fibres compared to dystrophic ones. Another difference was that in normal fibres the mean activity declined to a constant level in mature animals older than about 3 months. In contrast, the activity in dystrophic muscles appeared to fall exponentially throughout life. The functional significance of these findings is discussed.

Quantitative cytochemistry of beta-galactosidase in normal and enzyme deficient (gal) pollen of Brassica campestris: application of the indigogenic method

The available cytochemical methods for localization of beta-galactosidase have been evaluated using pollen grains of Brassica campestris. beta-Galactosidase-deficient pollen (gal), served as a control. Azo dye methods involving naphthyl substrates showed high and nonspecific background staining to the exine. The indigogenic method, employing 5-bromo-4-chloro-3-indoxyl beta-D-galactoside (X-gal) as the enzyme substrate, gave specific opaque-blue final reaction product, while mutant pollen grains remained colourless. Final reaction product formation was blocked by D-galactono-1,4-lactone, thus demonstrating the specificity of the enzyme reaction. Using microspectrophotometry, the absorbance of the final reaction product was found to be a linear function of incubation time and section thickness in cryostat sections up to 8 micron thick and was only slightly reduced by glutaraldehyde prefixation. The validity of the indigogenic method for quantitative analysis was confirmed by using an enzyme-containing polyacrylamide gel model system and enzyme-coupled Sepharose 4B beads. Cellular sites of enzymic activity have been determined using plastic sections: final reaction product occurred in the intine wall layer and peripheral cytoplasm.

Lysosomal modifications in human proximal tubule induced by aminoglycoside treatment: visualisation by light microscopical cytochemistry

In cryostat sections of kidney biopsies, lysosomes were visualized for light microscopy by staining for acid phosphatase. Twenty patients treated with the antibiotics gentamycin, tobramycin, amikacin or netelmicin during four days were compared to ten untreated control biopsies. Because of the marked heterogeneity of enzyme reaction product through the nephron, the most strongly stained tubular sections were used for comparison. With the exception of one biopsy, all treated kidneys display heavier staining than all controls; the difference is significant. Biochemical assays of acid phosphatase activity in homogenates have not revealed this difference. The cytochemical method may be used to detect early alterations caused by nephrotoxic drugs.

Acid phosphatase activity of human gingival fibroblasts measured using a simultaneous coupling semi-permeable membrane technique

Acid phosphatase activity has been measured in cultured human gingival fibroblasts using a validated histochemical simultaneous coupling semi-permeable membrane technique. The histochemical reaction was linear over a three hour incubation period and had a pH optimum of 5.0. The activity was not increased by prior exposure to hypotonic acetate buffer and was inhibited by fluoride and molybdate but not by formaldehyde. These results indicate that the semi-permeable membrane technique described may be used for observing and measuring acid phosphatase activity in cultured fibroblasts. From results obtained using inhibitors, it appears that in these cells most of the acid phosphatase observed is lysosomal. The absence of any activation of activity following pre-incubation with hypotonic buffer indicates that the method is not suitable for monitoring lysosomal membrane function.

Quantitative histochemical investigations of semipermeable membrane techniques for the assay of acid phosphatase in skeletal muscle. IV. A post-coupling technique

A post-coupling semipermeable membrane technique for determining the activity of acid phosphatase in sections of skeletal muscle has been developed and investigated for its reproducibility and validity. Cryostat sections of unfixed muscle mounted on dry dialysis membranes are first incubated for 1-4 at 37 degrees C on a gelled medium containing 4 mM naphthol AS-BI phosphate buffered at pH 5. They are next transferred to another gel containing only hexazotised Pararosanaline and incubated for a further 30 min. Finally, they are treated with 70% ethanol, dried in air, and mounted. The final reaction product (FRP) deposited within muscle fibres is mostly distributed as a fine reticular network, tentatively identified as sarcoplasmic reticulum. Large FRP "granules' of the kind observed with Meijer's simultaneous coupling membrane technique are not formed. The method is reproducible and valid in terms of several working criteria. For example, the mean absorbance of the FRP at its absorption maximum increases linearly with incubation time; and in model sections containing various amounts of a subcellular fraction rich in acid phosphatase, the mean absorbance after a constant incubation time is proportional to the enzyme concentration. FRP is formed at approximately twice the rate it is deposited in the simultaneous coupling method. The most important advantage of the post-coupling method over the simultaneous coupling method is that the inhibition of the enzyme by coupling reagents is avoided.

Quantitative histochemical investigations of semipermeable membrane techniques for the assay of acid phosphatase in skeletal muscle. II. Non-specific reactions in control sections

The absorbances of skeletal muscle fibres at 530 nm in control sections of either fresh or boiled tissue, incubated according to Meijer's semipermeable membrane technique for acid phosphatase, increase linearly with incubation time. Moreover, the absorbances continue to increase even after the incubation has been terminated by immersion of the sections in formalin. The comparatively weakly absorbing yellow reaction product originally formed is transformed with 24 h of mounting the sections into a strongly absorbing purple material with an absorption maximum at 570 nm. The original yellow product seems to be hexazotised Pararosanaline adsorbed onto tissue proteins. The formation of the purple product can be prevented by treating control sections immediately after incubation with 70% ethanol for 30 min at room temperature in place of formalin. Ethanol stabilises the yellow non-specific reaction product but does not extract it from tissue sections. The ethanol treatment thus seems useful for improving the validity of Meijer's technique.