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Biomedical subjects

M Jontell

Publications and source records attributed to M Jontell.

At least 73 records · Page 4Linked to original sources
PubMed1986

Stimulation of maturation of large immature histamine-containing basophilic cells from human peripheral blood, cord blood and bone marrow.

The development of FcR epsilon-bearing histamine-containing basophilic cells was studied in cultures of peripheral blood leucocytes and bone marrow leucocytes from normal individuals. The determination of basophilic cells was performed blindly. Before cultivation there were fairly similar numbers of basophilic cells in the samples from the three different sources (1.6 +/- 1.6 n = 13; 1.4 +/- 2.0 n = 21; 4.3 +/- 4.7 n = 8, respectively). During cultivation spontaneously appearing large blast-like basophilic cells were seen in good correspondence with a formation of histamine in the cultures (Spearman rank correlation coefficient = 0.9135, n = 13, P less than 0.001). This was more accentuated with bone marrow cells than with peripheral blood and cord blood cells. Conditioned medium (CM) was prepared from cells isolated from various tissues and stimulated by different means, e.g. peripheral blood from atopic individuals stimulated with allergen and unstimulated tonsil cells. Addition of the CM resulted in increased development of histamine-containing basophilic cells. Optimum stimulation was achieved with 10% CM. The basophilic stimulation by CM, as assessed as indices vs. unstimulated cultures, was more accentuated in cultures of peripheral blood cells than of bone marrow and cord blood cells (2.8 +/- 1.2; 1.8 +/- 0.5; 2.0 +/- 0.4, respectively). In contrast, the histamine formation was particularly evident in stimulated cultures of bone marrow cells, where more than four-fold increases of histamine were found. In bone marrow cells the histamine levels per basophilic cell also increased, whereas this was not the case in cord blood cells. A pronounced development of basophilic cells was achieved when using leukoagglutinin, provided the mitogen in the CM was eliminated. The formation of basophilic cells was prevented with mitomycin c and cycloheximide. In conclusion, the system described may provide important information on the development of histamine-containing basophilic cells at various maturation stages from different compartments, and mechanisms in a developing atopic disease.

Basophils↗
PubMed1985

An oral and psychosocial examination of patients with presumed oral galvanism.

The present investigation was performed to elucidate possible etiological factors behind the complaints reported by 62 patients referred because of presumed oral galvanism. Twenty-nine patients, matched with a subsample of the test group regarding age and sex, comprised a control group. The patients were examined regarding oral medical and stomatognathic health. Their psychological and social health and symptoms were evaluated by means of a standardised interview and 5 self-rating questionnaires. A complex symptomatology including symptoms from both the oral regions and other parts of the body constituated the most distinctive feature of the patients in the test group. The clinical examination as well as patient-perceived symptoms revealed high prevalences of parafunction and dysfunction in the muscles of the stomatognathic system. Furthermore, general complaints were mainly related to muscles of the extremities, and diseases of the joints and muscles were the most commonly reported disorder. The findings at the oral medical examination revealed no differences between the groups, except for signs of parafunction. Patients in the test group gave evidence of being more exposed to negative social events and the results clearly indicate a psychogenic component behind the reported complaints.

Electrogalvanism, Intraoral↗
PubMed1984

Assessment of Langerhans' cells in oral lichen planus using monoclonal antibodies.

In order to demonstrate Langerhans' cells in epithelium of oral lichen planus, monoclonal antibodies were used as immunological markers in combination with immunohistochemistry. By the use of anti-Ia antibodies the Langerhans' cells were shown to express an increased number of Ia-like antigens in comparison to the amounts found in healthy oral mucosa. The subepithelial infiltrate of mononuclear cells expressed identical Ia-like antigens on their surfaces. With anti-T6 antibodies as immunological markers, the number of Langerhans' cells was found to be virtually identical in diseased and healthy epithelium. Treatment of oral lichen planus with tretinoin resulted in a decrease of epithelial Ia-like antigens compared with the number found in untreated lesions. However, treatment with tretinoin did not alter the frequency of Langerhans' cell marked with anti-T6 antibodies. The present data demonstrate an increased amount of Ia-like antigens per number of T6-positive Langerhans' cells in diseased oral mucosa compared to healthy conditions. The increased expression of Ia-like antigens on Langerhans' cells and the contemporary finding of Ia-like antigens on the subepithelial T-cells support the opinion that the pathogenesis of oral lichen planus is mainly a cell-mediated type of immunological reaction.

Antibodies, Monoclonal↗
PubMed1984

Effects of dentists' behavior on patients' attitudes.

A group of 16 patients received Class II restorations at two different sessions. During one session a dentist interacted positively with the patient. During another session, the dentist had little interaction with the patients. Patients' ratings indicated that both dentists were perceived as equally competent but that the dentist who interacted with the patients was rated significantly better. It is possible that dentists will gain more satisfaction from their patients as they increase their interaction.

Adult↗
PubMed1983

Non-collagenous proteins of predentine from dentinogenically active bovine teeth.

Predentin(e) was dissected out from unerupted permanent bovine teeth. The non-collagenous proteins were extracted at -13 degrees C by 4 M-guanidinium chloride containing proteinase inhibitors and separated by DEAE-Sepharose and Sephadex G-100 chromatography. In addition to a few minor constituents, the only major non-collagenous components that could be demonstrated were albumin and proteoglycan. The localization of the former, demonstrated by optical-microscopical immunochemistry, was such that it was concluded that albumin is not a constituent of predentin matrix. Very low amounts of phosphoprotein were found in predentin matrix. This was of two types, high- and low-phosphorylated. Larger amounts of phosphoprotein were not present until the dissection was carried deeper into newly formed dentin(e). On the basis of the present results and previously obtained morphological data the conclusion was drawn that predentin matrix, containing virtually only collagen type I and proteoglycan, is similar in composition to that of loose connective tissue and primarily aimed at the production and maturation of collagen fibres. Only immediately before the mineralization front are the non-collagenous protein components secreted that initiate and govern calcium-phosphate mineral formation.

Amino Acids↗
PubMed1983

Noncollagenous proteins of rat compact bone.

In order to obtain a comprehensive overview of the noncollagenous proteins (NCPs) of bone matrix, the NCPs were extracted from rat compact bone and fractionated using methods aiming to prevent artifactual degradation and losses of protein. The NCP content of rat bone was found to be similar to that of rat dentin in several respects but different in others. The soluble NCPs of bone fell into four categories: acidic glycoproteins, gamma-carboxyglutamate-containing proteins, phosphoproteins, and proteoglycans. With the exception of the gamma-carboxyglutamate-containing proteins, the majority of NCPs had apparent molecular weights exceeding 50,000. As in rat dentin, several gamma-carboxyglutamate-containing proteins could be demonstrated in rat bone. Earlier studies have only taken one molecular species into consideration. No highly phosphorylated phosphoprotein could be demonstrated in bone. However, at least two phosphoproteins with a low degree of phosphorylation were found to be present. No plasma proteins could be demonstrated in any of the chromatographic fractions from the EDTA extracted NCPs by means of double diffusion. The NCPs, remaining firmly associated with the collagenous matrix after thorough demineralization and extraction, were analyzed after CNBr and collagenase degradation of the matrix. Much smaller amounts of phosphoprotein were recovered after CNBr digestion than reported earlier. Collagenase digestion released small amounts of acidic glycoprotein, phosphoprotein, and proteoglycan. The results give additional evidence that this small remainder might be explained, not by any covalent linkage to collagen, but by an inefficient extraction.

Amino Acids↗
PubMed1982

Disagreement in molecular weight determinations of dentin phosphoprotein.

The molecular weight of highly phosphorylated phosphoprotein from rat incisor dentin was estimated by three different methods: sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, gel chromatography in 6 M guanidinium chloride (GdnHCl) and analytical ultracentrifugation at high salt concentration. SDS-polyacrylamide gel electrophoresis revealed an abnormal migration of the phosphoprotein and its enzymatically dephosphorylated derivative in comparison to standard proteins. Depending on the acrylamide concentration in the gel (7.5-20%), the apparent molecular weight of the phosphoprotein varied from 90,000 to 27,000. Similar results were obtained for the dephosphorylated protein. In gel chromatography using 6 M GdnHCl as eluent the phosphoprotein had an elution volume corresponding to that of a standard protein with a molecular weight of 67,000, while the enzymatically dephosphorylated phosphoprotein showed an apparent molecular weight of 30,000. The phosphoprotein behaved non-ideally in equilibrium sedimentation runs. The apparent molecular weight was strongly concentration-dependent and the extrapolation to zero concentration was uncertain. However, after enzymatic dephosphorylation the concentration dependence disappeared and a molecular weight of 28,000 could be calculated. Since the phosphate groups represent 26% of the phosphoprotein by weight, the true molecular weight of the highly phosphorylated phosphoprotein components from rat incisor dentin should be 38,000. The study shows that it is not possible directly to estimate the molecular weight of this type of protein by standard methods elaborated for normal globular proteins.

Animals↗
PubMed1982

Localization of fibronectin during dentinogenesis in rat incisor.

Fibronectin (FN) was localized in the dental pulp and predentine at different stages of dentinogenesis by indirect immunofluorescence. Fibronectin was present in the basement membrane between the inner enamel epithelium and the underlying dental mesenchyme and also in mantle predentine. Fibronectin was absent from predentine during further (circumpulpal) dentine formation, indicating that the FN molecule is not directly involved in mineralization. The findings emphasize the difference between the mantle and circumpulpal dentine formation. Fibronectin was localized in the odontoblast layer at the level where the cell processes leave the cell bodies and where the odontoblasts adhere to each other by junctional complexes.

Animals↗
PubMed1981

Ca2+-binding studies of the phosphoprotein from rat-incisor dentine.

Rat incisor dentine was demineralized and extracted with 0.25 M EDTA containing protease inhibitors. The extract was purified by chromatography on DEAE-cellulose and sulfonated polystyrene. The Ca2+-finding properties of the phosphoprotein were studied by dynamic dialysis and by using a Ca2+-selective electrode. Two different binding sites were detected with Kd = 0.9 X 10(-7) M and 1.1 X 10(-5) M and displaying a Ca2+-binding capacity of 127 and 176 mol bound Ca2+/mol protein, respectively, assuming a molecular weight of 30 000. Upon enzymatic dephosphorylation of the phosphoprotein, the highest affinity sites disappeared and those with the lowest affinity were reduced. The optimum for Ca2+ binding by the phosphoprotein occurred at pH 8.2. The specificity of the Ca2+ ion interaction with the phosphoprotein was investigated by studying the competitive nature of other divalent and monovalent cations. It was found that Ca2+ ions were to a large extent displaced from the phosphoprotein by other cations in physiological concentrations.

Animals↗
PubMed1980

Comparative studies of phosphoprotein preparations from rat incisor dentin.

Phosphoprotein was obtained from rat incisor dentin either by extraction at elevated ionic strength after acetic acid demineralization, or by extraction simultaneous with demineralization in neutral EDTA solution. Purification of solubilized proteins was achieved by Sepharose 4B and DEAE-cellulose chromatography. Polyacrylamide gel electrophoresis of the material from the two preparations resulted in one single band. Except for the amino acid analyses, no evidence for a difference between the two phosphoprotein preparations could be found. After additional purification by iso-electric focusing the amino acid analyses demonstrated a similar composition. It is concluded that the two methods for phosphoprotein extraction yield the same product when purified properly. The study did not give any unequivocal answer as to if any phosphoprotein component exists in rat incisor dentin which is covalently linked to the collagen matrix.

Amino Acids↗
PubMed1980

Cation binding by the rat-incisor-dentine phosphoprotein. A spectroscopic investigation.

Nuclear magnetic resonance and electron paramagnetic resonance spectroscopy have been used to quantify metal binding to the phosphoprotein extractable from demineralized rat incisor dentine. Paramagnetic cation probes enable identification of the metal binding sites. Cations are able to diffuse across the protein surface while forming a relatively long-lived metal-phosphoprotein complex. The ability of the protein to sequester surface-mobile Ca(II) is discussed in terms of its ability to act as a possible nucleation site for the initial localization of Ca(II) within the dentine matrix.

Animals↗
PubMed1980

Effect of macromolecules on adherence of Streptococcus mutans.

The influence of macromolecules on the adherence of S. mutans was studied in an in vitro incubation system using 3H-labeled bacteria and hydroxyapatite beads. The bacterial adherence was strongly inhibited by treating the beads with an extremely acidic macromolecule. An even more pronounced effect was found when this substance was present during the incubation. To the contrary no effect was discernible when the bacteria only were pretreated with the acidic macromolecule. Even the basic substance decreased the adherence of the bacteria but to a less extent. The bacterial surface has a net negative charge and attracts basic molecules while hydroxyapatite beads analogously appear to have a net positive charge and attract acidic macromolecules. This adsorption of macromolecules might be a phenomenon of importance for the microbial colonization of teeth.

Adhesiveness↗
PubMed1979

Separation of odontoblast Ca2+-ATPase and alkaline phosphatase.

Ca2+-ATPase activity was solubilized, partly purified, and separated from nonspecific alkaline phosphatase activity (APase1) of dentinogenically active rat incisor odontoblasts. Attempts were made to extract the enzymes by various agents, such as Triton X-100, deoxycholate, butanol, EDTA, and buffers of decreasing ionic strength. Solubilization by butanol followed by extraction with low concentrations of EDTA proved to be most effective. Purification and separation were done by molecular sieve chromatography. Ca2+-ATPase showed no activity against p-nitrophenyl phosphate (p-NPP) or inorganic pyrophosphate (PPi) and was unaffected by R 8231 [+/-)-6(m-bromophenyl)-5,6-dihydroimidazo(2,1-b)thiazole oxalate]. It was activated by Ca2+ and Mg2+ ions in equimolar concentrations with the substrate. The enzyme was rapidly inactivated in the solubilized state. An apparent molecular weight of about 18,000 was obtained from molecular sieve data. APase, showing activity against ATP, PPi, and p-NPP, was virtually totally inhibited by R 8231. It was activated by Mg2+ ions but slightly reduced in activity by Ca2+ ions. It had an apparent mol. wt. of 79,000. The results provide direct evidence for earlier suggestions of the existence in hard tissue forming cells of two phosphatases active at alkaline pH.

Alkaline Phosphatase↗
PubMed1978

Isoelectric focusing of the phosphoprotein of rat-incisor dentin in ampholine and acid pH gradients. Evidence for carrier ampholyte-protein complexes.

Rat-incisor phosphoprotein (RIP) has been subjected to isoelectric focusing at 4 degrees in (a) an Ampholine pH gradient of 2.5-4 and (b) an acid pH gradient created by electrolysis of a system of acids and acidic ampholytes and covering the pH range 0.5-3.5. In the Ampholine gradient, the RIP unexpectedly formed several adjacent and strongly opalescent bands in the pH range 2.5-3.1. These bands, which migrated slowly toward the anode on prolonged focusing, are interpreted as being the result of an interaction between the amino groups of the Ampholine and the numerous phosphate groups of the protein. In the acid pH gradient, the RIP focused into one narrow zone corresponding to an isoelectric pH of 1.1 at 4 degrees. This value is consistent with the amino-acid composition and the phosphate content of the protein,

Animals↗
PubMed1978

Odontoblast metabolism in rats deficient in vitamin D and calcium. III. Protein synthesis in vitro.

Dentinogenically active rat incisor odontoblasts were dissected out from animals fed a low calcium, vitamin D free diet (R 25). Protein synthesis by these cells was studied by means of short-time incubation in an in vitro system in the presence of the radioactive labeled precursors L-leucine, L-fucose and L-proline. A significantly increased leucine and proline incorporation into the protein synthesized was noted in the cells from rats fed the deficient R 25 diet compared with odontoblasts from rats fed an adequate control diet (R 47). No difference between the two groups was found when fucose was utilized as a precursor. The well known increase in predentin width when feeding a rachitogenic diet may thus be explained by an increase in organic matrix synthesis in addition to the possible negative direct effects of lowered serum Ca content. Prior to this study, the behavior of proline as a precursor in the in vitro system was studied. The possibility of separating leucine-labeled proteins synthesized in the in vitro system by means of SDS-polyacrylamide gel electrophoresis was also shown.

Animals↗
PubMed1975

Leucine and fucose incorporation into odontoblast protein.

Odontoblasts isolated from rat incisors were incubated in vitro in the presence of tritiated leucine or fucose, and the amount of precursor incorporated into TCA-recipitated proteins was determined. The effect on precursor incorporation of varying the total precursor concentration was examined. The incorporation of leucine and fucose into TCA-precipitated proteins was found to be linear with time for at least 90 min. Inhibition studies with puromycin, cycloheximide and chloramphenicol demonstrated the presence of odontoblastic protein synthesis. One hour after in vivo administration of triated leucine the highest specific activity of odontoblast-predentin protein material was noted the corresponding maximum for pulp proteins was found to occur after 30 min. The in vivo incorporation of triated fucose was maximal after 4 h in both odontoblasts and pulp tissue.

Animals↗