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Biomedical subjects

L Hammarström

Publications and source records attributed to L Hammarström.

At least 343 records · Page 19Linked to original sources
PubMed1982

Characterization of human lysozyme (muramidase)-releasing cells. Organ distribution and functional properties as analyzed in a protein A plaque assay.

Using a modification of the protein A plaque assay, human lysozyme-releasing cells were detected as plaque-forming cells (PFC). Blood and bone marrow contained higher numbers of muramidase secretors compared to adenoid and tonsil cell suspensions. Human peripheral blood cell cultures were found to contain cells detected as PFC in the presence of antimuramidase immunoglobulin as a developing agent. Lysozyme-producing cells were also found in human bone marrow cultures. High cell densities and a short culture period were optimal conditions for lysozyme release in bone marrow cell cultures. Addition of the activating ligand lipopolysaccharide directly into the plaque assay altered the number of muramidase-secreting cells.

Antibody-Producing Cells↗
PubMed1982

Formation of intermediate cementum. III: 3H-tryptophan and 3H-proline uptake into the epithelial root sheath of Hertwig in vitro.

The intermediate cementum is a narrow, mineralized tissue between the cementum and dentin. Recent studies have shown that this tissue is mineralized by the epithelial root sheath in a way similar to the mineralization of the innermost layer of aprismatic enamel. In the present investigation uptake of proline and tryptophan into the epithelial root sheath was studied with autoradiography. Tryptophan is an amino acid that is incorporated into enamel matrix but not into collagen. Tryptophan uptake was significant in the whole epithelial root sheath, but not into the odontoblasts or predentin. Proline was incorporated into the predentin while the root sheath was unlabeled. This indicated that the matrix of the intermediate cementum was formed by the epithelial root sheath of Hertwig, and that this matrix was a noncollagenous matrix possibly of the same nature as enamel matrix.

Animals↗
PubMed1981

In vitro induction of human suppressor T cells by a chorionic gonadotropin preparation.

Human chorionic gonadotropin (hCG) in physiological retroplacental concentration has been shown to possess the capacity of inducing human lymphocytes which are subsequently competent to depress an antibody response induced by purified protein derivative of tuberculin, phytohemagglutinin, lipopolysaccharide and pokeweed mitogen. These suppressor cells inhibited the T cell-dependent mitogen-induced activation of lymphocytes synthesizing IgM, IgG and IgA. No suppression by hCG-induced cells was observed in Epstein-Barr virus activated cell cultures, indicating a T cell origin of the target cell. It is suggested that this may represent a mechanism for the cellular basis of an hCG-induced immunosuppressive effect in pregnancy.

Adult↗
PubMed1981

Effect of storage in media with different ion strengths and osmolalities on human periodontal ligament cells.

The viability of the periodontal ligament (PDL) cells is critical for the successful healing of replanted exarticulated teeth. It is mainly dependent on the duration of the extra-alveolar time and the storage medium. Saliva has usually been recommended as the most suitable storage medium, but recent experimental studies indicate that milk is preferable. In the present study the effect on cultured PDL cells of saliva and milk has been compared with some reference media such as tap water or saline by means of a 3H-uridine leakage test. Storage in milk or saline was found to cause much less 3H-uridine leakage than storage in saliva or tap water. Cells stored in milk for 60-180 min showed about the same leakage as cells stored in saline or Hanks' balanced salt solution. Osmolality measurements showed that saliva was hypotonic, while the osmolality of milk ranged within physiological limits. When the osmolality of saliva was increased by addition of NaCl the leakage of the stored cells decreased to the level of cells stored in 0.9% NaCl or milk.

Animals↗
PubMed1981

Periodontal healing of exarticulated monkey teeth stored in milk or saliva.

Saliva has usually been recommended as a storage medium for exarticulated teeth. Recent tissue culture studies have, however, shown that milk has a more suitable osmolality than saliva and that milk is a better storage medium for human periodontal ligament cells. In the present investigation periodontal healing of replanted monkey teeth has been studied after storage of teeth in milk or saliva before replantation. There was much less root resorption, especially inflammatory resorption, after storage in milk than in saliva. Storage of teeth in milk for 3 h before replantation resulted in the same low frequency of root resorptions as was seen after immediate replantation. There was hardly any replacement resorption (ankylosis) seen in the replanted teeth.

Animals↗
PubMed1981

Relationship between plasma, dentin and bone fluoride concentrations in rats following long-term fluoride administration.

A detailed knowledge of fluoride (F) pharmacokinetics is necessary if its pharmacologic and toxicologic effects are to be adequately understood. In the present study plasma F concentrations have been analysed using repeated blood samples taken from the ethmoidal sinus of rats given 25, 50, 100 and 150 p.p.m. F in drinking water ad libitum for 79 days. A close relationship between the F-concentration in the drinking water and plasma F concentrations was found. When the administration of F was stopped, a rapid decline in plasma F concentration was noted during 48 hrs in all groups. The plasma F concentrations in the 25 p.p.m. group returned to preexperimental levels but remained elevated in the other groups. The F concentrations of dentin and bone were determined and calculated on a dry fat free basis. The results show that there was a close relationship between plasma, bone and dentin concentrations.

Animals↗
PubMed1981

Enzyme histochemistry of developing rat oral mucosa.

The oral mucosa of developing and mature rats was analyzed histochemically for regional enzyme differences. The following enzymes were studied: nonspecific alkaline phosphatase (alkpase), acid phosphatase (acidpase), 5'-nucleotidase (AMPase), adenosine triphosphatase (ATPase), succinate dehydrogenase (SDH), lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G-6-pDH). All enzymes were active in the oral mucosa, but regional as well as tissue variations were observed. Epithelium in all regions showed acidpase staining. Oxidoreductases were found in all regions with variations within the epithelium. The epithelium of specific regions stained for alkpase and AMPase, while adjacent epithelium did not. We suggest that the alkpase and AMPase activities are associated with specific functions of the epithelium in these regions.

Aging↗
PubMed1981

Focal epithelial hyperplasia in Sweden.

A prevalence of 0.11% of focal epithelial hyperplasia (FEH) was found among 20,333 adult Swedes. There was no sex difference, the lesion was most prevalent in age groups above 45 years and the lesion was most frequent on the tongue. The frequency of FEH in 15,132 consecutive routine biopsies was 0.26%. Four FEH-cells were ultrastructurally examined. They exhibited a clear cytoplasm with scattered ribosomes, a peripheral condensation of tonofilaments, a central aggregation of chromatin clumps with loss of nuclear membrane and an accumulation of desmosome fragments. No viral particles could be identified in these FEH-cells.

Adolescent↗
PubMed1981

Polyclonal human T lymphocyte activation results in the secondary functional activation of the human B lymphocyte.

The polyclonal T lymphocyte activators Con A and PHA were demonstrated to induce secretion of IgM and IgG as well as IgA antibodies in cultures of human peripheral blood lymphocytes. A similar response was seen in one-way mixed lymphocyte cultures and the kinetics, dose-response characteristics and optimal culture conditions are presented. The presence of functional T lymphocytes is a prerequisite for in vitro B lymphocyte activation in response to T lymphocyte mitogens. A narrow dose-response profile is a characteristic for both Con A and PHA and polyclonal B cell activation occurred at what have been previously regarded as suboptimal concentrations of these agents. The use of higher doses of these activators failed to generate immunoglobulin-secreting cells despite the presence of early and optimal levels of DNA synthesis in the cultures.

Adult↗
PubMed1981

Detection of IgD-secreting human lymphocytes at the single cell level by a protein A plaque assay.

By the use of Staphylococcus aureus protein A-coupled erythrocytes as target cells, and anti-Ig antibodies as a developing serum, immunoglobulin-secreting cells can be detected as plaque-forming cells in a complement-dependent haemolytic plaque assay. This method is based on the fact that the Fc portion of IgG will bind to protein A molecules. Using a rabbit anti-human IgD immunoglobulin as a developing serum we were able to detect secretion of IgD molecules from human cells. In a patient with an IgD myeloma, 6% of the bone marrow cells were found to form plaques. Bone marrow cells and blood lymphocytes from healthy donors as well as human tonsil cells were also examined for delta chain secretion. In some donors, a low increase in plaque numbers was obtained when anti-IgD Ig was used as a developing agent. In spite of the fact that the antisera used were highly specific we cannot rule out the possibility that the increase was due to cross-reactivity. However, these findings clearly demonstrate that the release of IgD from normal human lymphoid cells occurs at a much lower level as compared to secretion of IgM, IgG or IgA.

Adult↗
PubMed1980

T-cell functions in nude mice: proliferation of spleen cells from athymic mice in the one-way xenogeneic mixed leucocyte reaction.

Spleen cells from nude mice proliferate in vitro when stimulated with xenogeneic (human) lymphoid cells rendered unresponsive by addition of digitalis glycosides. In digitalis-sensitive species, such as humans, DNA, RNA, carbohydrate, and protein synthesis is completely blocked by addition of low concentrations of glycoside, whereas no impairment is found in digitalis-resistant species such as mouse. Since T cells have been implicated to be the cells responding in the mixed leucocyte reaction, this finding may suggest the occasional existence of "T-like" cells in the spleens of nude mice.

Animals↗
PubMed1980

Mitogenic activation of human lymphocytes: a protein A plaque assay evaluation of polyclonal B-cell activators.

Using the protein A plaque assay, the capacity of various polyclonal B cell activators to induce differentiation in human B lymphocytes was investigated. Dextran sulphate and native dextran were both virtually devoid of mitogenic properties. Lipopolysaccharide, however, was found to be a potent mitogen in human cells that, although giving rise to low DNA synthetic response, induced high numbers of immunoglobulin-synthesizing cells. Mean plaque-forming cell (PFC) numbers in healthy blood donors assayed on the optimal day (days 5-7) were 23,493 IgM/10(6) cells, 11,288 IgG/10(6) cells, and 2643 IgA/10(6) cells. Values obtained in spleen cells, peaking at days 4-6, were slightly higher. Purified protein derivative (PPD) was equally or even more effective than lipopolysaccharide (LPS) in generating PFC of different subclasses in peripheral blood with mean of 29,241 IgM/10(6), 21,269 IgG/10(6), and 3681 IgA/10(6). PPD furthermore induced a marked DNA synthetic response in human lymphocytes. These data suggest that LPS and PPD may both be used as functional markers in human cells when analysing patients with a suspected immunodeficiency state. It is suggested that cultures should be assayed using the protein A plaque assay, thereby being able not only to investigate the individual immunoglobulin classes but also to avoid the possible hazards involved in measuring antigen-specific responses in patients whose prior immunization to the antigen tested can never be totally excluded.

B-Lymphocytes↗
PubMed1980

Detection of muramidase (lysozyme)-secreting leucocytes at the single-cell level by a protein A plaque assay.

Using a modification of the protein A plaque assay, muramidase (lysozyme)-producing leucocytes were detected as plaque-forming cells. In the presence of anti-muramidase Ig and complement the secreted lysozyme resulted in lysis of protein-A-coated target erythrocytes. By the use of a monolayer technique individual plaque-forming cells could be identified by staining procedures. Granulocytes as well as monocytes were found to produce muramidase and thus to form plaques. This method could serve as a useful tool when studying lysozyme secretion. Furthermore, by the use of appropriate antisera, this method could be employed for the study of any cell type (any secretion), provided enough molecules are being secreted.

Cells, Cultured↗
PubMed1980

Evidence in favor of an anti-invasion factor in cementum or periodontal membrane of human teeth.

A casein-agar method for the detection of protease inhibitors has been used on human teeth. Periodontal membranes or cementum have been shown to contain a potent collagenase inhibitor. This inhibitor might explain why the roots of teeth are normally protected against resorption. A similar protease inhibitor has recently been demonstrated in cartilage and there it was called an anti-invasion factor.

Dental Cementum↗