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Biomedical subjects

G Hasselgren

Publications and source records attributed to G Hasselgren.

15 recordsLinked to original sources
PubMed1979

A method for toxicity screening of biomaterials using cells cultured on millipore filters.

In the present paper a tissue culture technique is described whereby the toxicity of setting and solid materials may be evaluated. A cell monolayer was established on a millipore filter which was placed on an agar medium, cell side down. Test specimens were placed on top of the millipore filter and were allowed to influence the cells through the filter for two hours. The cell reaction was assessed by incubating the cells, still adherent to the filter, for the demonstration of succinate dehydrogenase activity. Materials with a cytotoxic effect caused a zone of inhibited enzyme activity in the cell-material contact area. The filters were examined macroscopically and scores from 0 to 3 were given to grade the severity of the cell response. Unset and set silicate cement, zinc phosphate cement and an acrylic resin were tested. The results obtained were consistent and in accordance with those of previous reports. The method was simple and rapid and appeared suitable for the assay of larger test series.

Animals↗
PubMed1979

Potential inhibitors of rat tooth alkaline phosphatase studied by means of different histochemical techniques.

Two histochemical methods for demonstration of alkaline phosphatase activity, a lead pyrophosphate- anda naphtholphosphate technique, were compared. Since different results may be due to methodological differences as well as different enzyme activities, the enzymatic hydrolysis of the naphtholphosphate was visualized both by means of an azo-dye coupler and by lead-capturing of the liberated phosphate ion. Various potential inhibitors of alkaline phosphatase activity (diphosphonate, D-penicillamine, and sodium fluoride) were also tested. The use of diphosphonate and D-penicillamine resulted in inhibited or reduced staining, which could mainly be explained by an interference by these compounds with components in the incubation media rather than with the enzyme itself. The addition of sodium fluoride had no effect on the naphtholphosphate staining pattern irrespective of capturing method, whereas the odontoblastic pyrophosphate splitting alkaline phosphatase appeared to be sensitive to sodium fluoride, suggesting the presence of two alkaline phosphatases in odontoblasts.

Alkaline Phosphatase↗
PubMed1978

Histochemical characterization of alkaline phosphatase in developing rat teeth and bone.

Alkaline phosphatase (EC 3.1.3.1.) in developing teeth and in bone has been studied. Prior to hard tissue function a rather high enzyme activity was noted in differentiating odontoblasts, stratum intermedium, and outer enamel epithelium. A lower activity was observed in the cells of the dental papilla and stellate reticulum. After the onset of hard tissue formation the alkaline phosphatase activity was generally increased. Enzyme activity was also found in the proximal part of tall, secretory ameloblasts. In the short postsecretory ameloblasts a high enzyme activity was noted. At the onset of dentin mineralization there was an increase in enzyme activity in the cells of the subodontoblastic layer. In bone the highest alkaline phosphatase activity was found in osteoblasts. A difference was noted between the alkaline phosphatase of hard and soft tissues by means of the addition of inhibitors to the incubation media. Within the hard tissues it was possible to distinguish between two alkaline phosphatases after pretreatment with heat (56 degrees C) or the addition of specific inhibitors (sodium metavandate, ortho-and pyrophosphate). An isoenzyme which was sensitive to these procedures was demonstrated in odontoblasts and in the pulpal connective tissue. Another alkaline phosphatase isoenzyme, which was resistant to pretreatment with heat or the addition of vanadate or phosphate, was demonstrated in the subodontoblastic cell layer, stratum intermedium and the outer cells of the reduced enamel epithelium.

Alkaline Phosphatase↗
PubMed1978

Alkaline phosphatase in developing teeth and bone of man and macaque monkey.

The activity of nonspecific alkaline phosphatase (E.C. 3.1.3.1) in developing teeth and bone of human fetuses and young macaque monkeys has been studied by means of histochemistry. The incubations for alkaline phosphatase were performed at pH 8.2 using naphthol-AS-MX-phosphate as substrate and Fast Blue RR salt or Fast Red Violet LB salt as couplers. By means of pretreatment with heat (56 degrees C), or addition of sodium metavanadate, ortho- or pyrophosphate, two alkaline phosphatases were demonstrated in the developing teeth. Prior to hard tissue formation all alkaline phosphatase activity was inhibited by the addition of vanadate, phosphate, or by pretreatment with heat. Pretreatment with heat or addition of vanadate or phosphate also inhibited alkaline phosphatase activity in the odontoblasts and in the pulpal connective tissue, whereas the activity in the subodontoblastic cell layer, stratum intermedium, outer enamel epithelium, and the the outer cells of the reduced enamel epithelium were much less affected. A week resistant activity was also noted in odontoblasts and pulpal connective tissue.

Alkaline Phosphatase↗
PubMed1978

A method for evaluation of initial tissue response to biomaterials.

In the present paper an implantation technique is described whereby the effect of the surgical operation is eliminated and initial tissue reactions to materials may be studied. A teflon body was implanted intramuscularly in rabbits. After six weeks the overlaying tissue was excised and the implant removed. An intact, nonepithelialized tissue surface was exposed, which due to the shape of the implant showed three indentations. Materials were placed in the indentations for 15 minutes and the tissue reaction was registered by enzyme histochemical methods. Silicate cement, zinc phosphate cement and a 4% phenol solution caused an inhibition in the dehydrogenase enzyme activity in the tissue subjacent to the indentations. The severity of the tissue reaction, indicated by the width of the inhibition zone, varied among the test materials. Silicate cement caused the widest inhibition zone and the phenol solution the narrowest one. These results correlate well with previous tissue compatibility studies and indicate that the method is applicable for in vivo screening of initial tissue response to biomaterials.

Animals↗
PubMed1978

Electrophoretic separation of alkaline and acid phosphatase isoenzymes from the pulp of monkey teeth.

Monkey pulps were homogenized in a Triton tris solution. After three centrifugation steps (800, 20000, and 105000 g) the supernatant was applied on acryl amide columns at pH 7.5 in a tris-diethyl barbituric acid buffer. Electrophoresis was performed at a constant current of 2.5 mA per gel column at 18--20 degrees C. Incubations for alkaline phosphatase (E.C. 3.1.3.1) were carried out at pH 8.3 using naphthol-AS-MX-phosphate as substrate and Fast Red Violet LB salt as coupler. Incubations for acid phosphatase (E.C. 3.1.3.2) were undertaken at pH 5.0 using alpha-naphtyl phosphate as substrate and hexazotized pararosanilin as coupling agent. After the incubations for alkaline phosphatase as well as acid phosphatase two bands showing enzyme activity were demonstrated. By means of treatment with heat (56 degrees C) prior to incubation or addition of vanadate or pyrophosphate to the incubation medium it was shown that the main part of the fast moving alkaline phosphatase band was sensitive to these procedures. The alkaline phosphatase of the slow moving band appeared to be resistant to heat or the addition of inhibitors.

Acid Phosphatase↗
PubMed1977

Pulpal status after autogenous transplantation of fully developed maxillary canines.

By means of histologic and histochemical studies of oxidative enzymes, the pulps of transplanted fully developed maxillary canines have been evaluated after an observation period of 3 to 25 months. No pulp had survived the transplantation trauma, and endodontic treatment of fully developed transplant teeth was considered to be a prerequisite to an optimal clinical result.

Adult↗
PubMed1977

Enzyme activity in the pulp following preparation of cavities and insertion of medicaments in cavities in monkey teeth.

The effect of cavity preparation, calcium hydroxide and a corticosteroid on pulpal enzymes (Alkaline phosphatase, acid phosphatase, beta-glucuronidase, cytochrome oxidase and succinate, lactate and glucose-6-phosphate dehydrogenase) in monkey teeth has been studied by histochemical means. Cavity preparation with an air turbine and sufficient spray apparently did not affect the enzyme activity of the pulp, nor did application of a corticosteroid to the cavity floor. Twenty-four hours after calcium hydroxide application an increase in enzyme activity was found in the ondontoblastic and subodontoblastic cell layers subjacent to the calcium hydroxide-covered dentin. This activity seemed to demonstrate an onset of dentin formation, and 15 days after the application a slight amount of secondary dentin was found subjacent to the cavities in these teeth.

Acid Phosphatase↗
PubMed1976

Histochemical demonstration of acid hydrolase activity in internal dentinal resorption.

The enzymes acid phosphatase (E.C. 3.133) and beta-glucuronidase (E.C. 3.2.1.31) have been demonstrated in dentin-resorbing cells by means of histochemistry. Addition of specific enzyme inhibitros revealed that the acid phosphatase of these cells was sensitive to fluride, copper, and m?OLYBDATE BUT RESISTANT TO Tartrate. The same pattern of enzyme activity has previously been found in bone-resorbing cells.

Acid Phosphatase↗
PubMed1976

The use of iodine as a contrast medium in endodontic therapy.

The present study describes the use of 10 per cent iodine in potassium iodide as an intradental x-ray contrast medium in the search for root canals or parts of root canals which were not detected in radiographs or by instrumentation. In most teeth with periapical radiolocencies a passage through the entire root was found by means of the contrast medium, but in the teeth without periapical involvement usually no communication was detected. According to the results of the present study, an intradental contrast medium may be useful in the search for apparently obliterated root canals.

Contrast Media↗
PubMed1976

Morphologic and enzyme histochemical observations on the pulp of human primary molars 3 to 5 years after formocresol treatment.

The state of the pulp of twenty-seven primary teeth treated by formocresol pulpotomy (clinically and radiographically successful) was assessed 3 to 5 years after treatment. A wide variation was found in the pulpal condition, from normal pulp tissue to total necrosis. Resorption and apposition of hard tissue were common findings. Five teeth were freeze-sectioned and incubated for histochemical demonstration of oxidative enzymes. The pulps of two teeth were vital; two teeth had necrotic areas subjacent to the amputation paste; and one pulp was totally necrotic. Six teeth were extracted 5 minutes after formocresol pulpotomy and incubated for demonstration of oxidative enzymes. An unstained zone, 1 to 2 mm. deep, was seen in all incubated sections. In conclusion, it seems that the formocresol method should be regarded only as a means to keep primary teeth with pulp exposures functioning for a relativley short period of time.

Dental Pulp↗
PubMed1976

Effect of formaldehyde-containing drugs on human dental pulp evaluated by enzyme histochemical technique.

The in vivo effect of formaldehyde on pulp tissue in short-term studies cannot be established by using routine histologic techniques because the tissue is exposed to a fixative in vivo as well as during the histologic preparation. The pulps of permanent premolars were amputated and zinc oxide with 4% formaldehyde or formocresol was used as wound dressing. The observation periods varied from 1 to 16 d. After extraction the teeth were freeze-sectioned, freeze-dried and then incubated for histochemical demonstration of some oxidative and hydrolytic enzymes. A demarcated border between apically stained and cervically nonstained pulp tissue was found in sections incubated for oxidative enzymes. When formocresol, which has a high concentration of formaldehyde, was used, the border was situated closer to the apex. This was also the case when the observation period was increased. The incubation for lactate dehydrogenase gave a high staining intensity. Thus the use of frozen sections in combination with the histochemical method for the demonstration of lactate dehydrogenase appears to be suitable for the study of the penetration of formaldehyde in pulp tissue in short-term studies.

Acid Phosphatase↗
PubMed1975

Histochemical studies on beta-glucuronidase activity in developing teeth and bone of rat and Macaque monkey.

The enzyme beta-glucuronidase (E.C. 3.2.1.31.) has been studied in developing teeth and bone of Sprague-Dawley rats and Macaque monkeys (Macaca Irus) by means of histochemistry using naphthol-AS-BI-beta-D-glucuronide as substrate and hexazotized pararosanilin as coupling reagent. Since beta-glucuronidase is sensitive to fixatives a freeze-sectioning technique has been used which made it possible to section highly mineralized tissues without previous fixation and decalcification. In the bone enzyme activity was found in osteoclasts and osteoblasts. beta-glucuronidase activity was found in teeth of both species in odontoblasts, ameloblasts, stratum intermedium, inner and outer enamel epithelium. When enamel matrix formation was completed as indicated by the reduction of ameloblast length the enzyme activity of the ameloblasts increased.

Ameloblasts↗