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Biomedical subjects

J P Germain

Publications and source records attributed to J P Germain.

5 recordsLinked to original sources
PubMed1992

Histochemical studies of acid and alkaline phosphatases in rat tooth germs with undecalcified resin-embedded specimens.

A novel technique for the histochemical demonstration of acid phosphatase (AcPase) and alkaline phosphatase (AkPase) in hard tissues has been proposed. Fresh, unfixed, undecalcified samples of rat tooth germs and surrounding structures were embedded in LR Gold resin at -20 degrees C. Sections of 2 microns were taken and subsequently processed for enzyme histochemistry. AkPase reaction product appeared as strong linear staining outlining cell boundaries and was present in the enamel organ, dental pulp, and osteoblast cells. Tartrate-resistant AcPase staining was seen exclusively in the osteoclasts of developing alveolar bone. Our results demonstrated that the use of unfixed, undecalcified LR Gold resin-embedded specimens for histochemistry is a novel technique which may be of value for certain studies when decalcification of specimens is undesirable. The technique appears to give good preservation of enzyme activity combined with the ability to prepare sections with excellent morphological detail.

Acid Phosphatase↗
PubMed1979

Rapid demineralization in acidic buffers.

The demineralization of routine histological specimens in buffers of weakly ionized organic acids, unbuffered formic acid, and EDTA was investigated. The rate of demineralization was measured by a chemical method and from radiographs. Lactate-containing buffers and buffers of formic acid with its potassium salt were more rapid in effect than any other agent. Acidic buffers and unbuffered formic acid produced rapid diffuse demineralization with secondary precipitation of calcium salts. Preservation of dental enamel in such buffers resulted from the significantly slower rate of enamel demineralization than that for bone and dentine. In rapid demineralizing agents the secondary salts were quickly redissolved while in slow buffers these salts persisted. Multivalent ions such as citrate and maleate slowed the rate of demineralization, and a citrate-containing buffer was the slowest of all the agents tested. Demineralization in EDTA exhibited a different pattern with the establishment of a well-defined front of demineralization without apparent reprecipitation. EDTA attacked enamel, bone and dentine at the same rate. An attempt was made to relate the observed rates of demineralization to current theories of the demineralization process.

Animals↗
PubMed1978

Dermatologic problems in amputees.

Improvements in surgical techniques and prosthetic devices and the establishment of prosthetic clinics have altered the outlook for the amputee. A cooperative effect on the part of professionals looking after amputee patients, as carried out in these clinics, offers the best means of recognition and treatment of difficulties as they arise. Until the "bionic man" becomes a reality, amputees will continue to have skin problems. In describing a number of illustrative cases, we have attempted to: (a) renew interest in these problems; (b) demonstrate the value of the group approach; and (c) encourage the participation of interested dermatologists in the prosthetic clinic team to facilitate earlier recognition and treatment of troublesome skin disorders in the amputee.

Adolescent↗
PubMedDate not supplied

The reversal of tissue differentiation around screws.

Mechanical factors influence the morphology and function of differentiated as well as undifferentiated cells. Observations of tissues surrounding screws, during a 4-week period of stability followed by a 4-week period of instability, demonstrate resorption of the newly formed callus and subsequently to screw lossening. Four weeks of instability followed by 4 weeks of stability produced not only a cessation of the osteoclastic activity, but also the appearance of an osteoclastic activity. Thus, the holding power of screws is not finally determined at the moment of their insertion nor after cellular differentiation has occurred around the screws. Local mechanical conditions throughout the period of fracture consolidation are of eqaul importance.

Animals↗