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Biomedical subjects

F P Altman

Publications and source records attributed to F P Altman.

At least 19 recordsLinked to original sources
PubMed1982

Enzyme histochemical changes in murine osteoarthritis.

Male mice of the STR/ORT strain spontaneously develop an osteoarthritic lesion in the medial tibial condyles. Histochemical studies of lactate dehydrogenase have previously shown that a region of completely inactive chondrocytes develops in the cartilage prior to degenerative changes. The present studies have shown a nearly parallel time course for the development of inactive cells and cartilage damage, except that there is a delay of four to five weeks between these two events. It is considered that the latter is a consequence of the former. The mechanism of the enzyme depletion is not known, but it probably extends to many, if not all, oxidative enzymes, and it is suggested that a disturbance in a hydrogen transport (cytochrome) system could account for the apparent lack of activity of many dehydrogenases as demonstrated by tetrazolium salt techniques.

Animals↗
PubMed1981

A metabolic dysfunction in early murine osteoarthritis.

Male mice of the STR/ORT strain spontaneously develop an osteoarthritis lesion in the medial tibial condyle. The appearance of the lesion is age-related and by about 15 months has affected almost all animals. Histochemical studies of lactate dehydrogenase and succinate dehydrogenase activities have shown that a region of inactive chondrocytes appears in the cartilage of these mice before major histological evidence of degeneration. It is suggested that this may be an early metabolic dysfunction, which subsequently leads to matrix breakdown due to the lack of essential enzyme cofactors.

Age Factors↗
PubMed1981

Some aspects of the use of tetrazolium salts in quantitative histochemistry.

The reduction of tetrazolium salts to highly coloured insoluble formazans is a reaction which has been widely exploited in histochemistry. This presentation considers three important aspects of the use of these compounds in quantitative studies, namely purity, intermediate reduction products, and calibration and measurement. Thin layer chromatography of tetrazolium salts from different suppliers has shown that standards of purity can vary widely, and that some samples are seriously contaminated. Studies with chromatographically pure compounds have demonstrated that the red diffuse colour seen in some reactions with di-tetrazolium salts is due to a half-reduced reduction intermediate. This "half-formazan" is part of the total activity, and cannot be disregarded in quantitative work. An understanding of the chemical nature of formazan end-products in tissue sections has made it possible to calibrate these reactions for microdensitometry.

Chromatography, Thin Layer↗
PubMed1979

Tissue stabilizer methods in histochemistry.

Quantitative studies in the 1960s established that the tissue disruption and enzyme loss which occurs when unfixed cryostat sections are incubated could be prevented with high concentrations of polyvinyl alcohol without inhibition of enzyme activity. This use of polymeric stabilizers has been largely confined to studies of 'soluble' dehydrogenases in tissue sections. However, optimum conditions for 'soluble' enzymes in cut sections may not be ideal for membrane-bound enzymes or for whole cells, where an over-stabilization of membranes can lead to restricted entry of reagents and thereby low activities. Lower concentrations, or other stabilizers such as Ficoll (a synthetic polysucrose) and collagen polypeptides, have been used in such cases. Suggested criteria for a tissue stabilizer are: (i) The stabilizer should be chemically inert, of defined and constant composition, and generally available; (ii) The tissue must remain structurally intact during the incubation, and the final preparation should look 'clean' and have the proper morphology; (iii) The component being assayed must remain inside the section, and not diffuse into the incubation medium. Ideally, it and any reaction product should remain at their original loci, although it may not always be possible to verify this; (iv) Recorded activities should be comparable to those found in biochemical systems under similar conditions.

Collagen↗
PubMed1977

Quantitative microscopy of enzyme reactions in tissue sections.

Microdensitometry makes it possible to measure reaction products in discrete regions of tissue sections. Single cells, or groups of cells, can be selected for measurement. In this way, it is possible to obtain quantitative data from enzyme reactions, and to relate activities to histology. Some examples are given to illustrate the application of this technique.

Animals↗
PubMed1976

The quantification of formazans in tissue sections by microdensitometry. I. The use of neotetrazolium chloride.

This article describes the use of a microdensitometer for the measurement of formazan deposits in tissue sections. Some examples are given to illustrate the various applications of this technique in the assessment of glucose-6-phosphate dehydrogenase activity. These are (I) the separate measurement of the red half-formazan intermediate and purple diformazan of neotetrazolium, and the effect of incubation time on their production, (2) the measurement of activities in different regions of the liver lobule, and the selective effect of phenobarbitone, and (3) the measurement of enzyme activity in individual cartilage cells in normal and osteoarthrosis-prone animals. All activities can be expressed in absolute units as nmol hydrogen/mm3/hr, and thus compared with standard biochemical data. The activities obtained all fall within the range of published values for biochemical systems.

Animals↗
PubMed1976

Tetrazolium salts: a consumer's guide.

The purities of seven tetrazolium salts, obtained from various commercial sources, have been assessed by thin layer chromatography, relative extinction coefficients, and melting points. MTT and INT were largely homogeneous on thin layer chromatography, although significant variations occurred in the melting point behaviour. All the samples of TT examined were contaminated to a small extent with non-tetrazolium u.v.-absorbing material. TNBT and NBT were contaminated with small amounts of mono-tetrazolium salts, although one sample of each was heavily contaminated with another di-tetrazolium compound. Four samples of TNBT contained high melting point contaminants. BT was also contaminated with mono-tetrazolium salts, and some samples also contained di-tetrazolium salt contaminants. NT was the most heavily contaminated of all, most samples containing no less than five separate tetrazolium compounds. Prices varied widely, and in general were not related to purity. Some catalogue entries were very easy to find; others were more difficult. Few specifications were given; of these, most were arbitrary (for example, pure, grade I, and ... probably the finest INT offered anywhere.

Chromatography, Thin Layer↗
PubMed1976

The quantification of formazans in tissue sections by microdensitometry. II. The use of BPST, a new tetrazolium salt.

This article describes the use of a microdensitometer for the measurement of BPST formazan in tissue sections. BPST is a new tetrazolium salt, 2-(2-benzothiazolyl)-3-(4-phthalhydrazidyl)-5-styryl-tetrazolium chloride, which produces a single, well-defined formazan, and is thus easily quantified. The formazan gives an excellent localization, since BPST was originally designed for ultrastructural work. Activities are expressed in absolute units as n moles hydrogen/mm3, and are thus directly comparable with standard biochemical data.

Animals↗
PubMed1976

The quantification of ormazans in tissue sections by microdensitometry. III. The effect of objective power and scanning spot size.

In this article, it is reported that the formazans derived from neotetrazolium chloride (NT) and 2-(2-benzothiazolyl)-3-(4-phthalhydrazidyl)-5-styryl-tetrazolium chloride (BPST) can be measured by microdensitometry of tissue sections with a wide range of scanning spot sizes, without any significant effect on the recorded extinctions. The spot sizes tested ranged from 0.20 to 16 mum. Thus when large fields have to be measured, it is possible to use low-power objectives and still obtain valid results.

Animals↗