The influence of freezing and freeze-drying of tissue specimens on enzyme activity

In the presented study the influence of freezing and freeze-drying on enzyme activity is described. Attention is paid to 16 enzymes which can be used for quantitative enzyme histochemical techniques. With the exception of succinate dehydrogenase only, no significant inactivation during freezing and freeze-drying procedures could be demonstrated with lactate dehydrogenase, malate dehydrogenase (NAD+), malate dehydrogenase (decarboxylating) (NADP+), isocitrate dehydrogenase (NADP+), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, NADH-oxydoreductase, mitochondrial glycerol-3-phosphate dehydrogenase, cytochrome c oxidase, phosphoglucomutase, glucosephosphate isomerase, glucose-6-phosphatase, acid phosphatase, beta-glucuronidase and non specific aryl esterase. Therefore, the results supply a sound foundation for those quantitative enzyme histochemical techniques in which tissue specimens are frozen or frozen-dried before enzyme estimations are performed.

Tissue considerations for mandibular subperiosteal implants

The criteria for the preoperative evaluation of the residual alveolar tissue for a potential implant patient have been discussed. To ensure a firm epithelial attachment around the implant post, the residual tissue at the point of oral penetration should be: (1) sufficient in amount or thickness and attached to the periosteum, (2) fibrous, not loose, areolar mucosa, and (3) positioned midway over the stress-bearing area for the implant and overlying prosthesis. If the existing tissue does not meet the above criteria, a free palatal graft can be placed over the point of oral penetration to improve the potential for tissue adaptation around the post.

Air pollution simulation and human performance

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