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T Lundgren

Publications and source records attributed to T Lundgren.

54 records · Page 3Linked to original sources
PubMed1992

Isolation of two novel sialyl-Lewis X-active oligosaccharides by high-performance liquid affinity chromatography using monoclonal antibody Onc-M26.

A monoclonal antibody, Onc-M26, that recognizes a cancer-associated antigen expressed by most human adenocarcinomas of the breast was shown previously to recognize a carbohydrate epitope carried on a hexaglycosyl ganglioside carrying the sialyl-Lewis X (SLex) antigen (P.S. Linsley et al., 1988, Cancer Res. 48, 2138-2148). Evidence that the antibody binds even more avidly to minor gangliosides containing more complex carbohydrate chains prompted us to search for a higher affinity epitope among sialylated oligosaccharides from pooled human milk. Affinity chromatography of a partially purified fraction of monosialylated milk oligosaccharides on a column containing monoclonal antibody Onc-M26 bound to a macroporous silica matrix gave a peak with a retention volume significantly greater than that of a standard SLex-active hexasaccharide. The retained material consisted of two nonasaccharides, each containing the SLex tetrasaccharide sequence, Neu5Ac alpha 2-3Gal beta 1-4(Fuc alpha 1-3) GlcNAc, linked beta 1-6 to a 3,6-disubstituted galactosyl residue.

Antibodies, Monoclonal↗
PubMed1992

Calcium ion activity and pH in the odontoblast-predentin region: ion-selective microelectrode measurements.

Ca2+ ion activities and pH were measured in the odontoblast/predentin region of rat incisors by means of the microelectrode technique. In Ringer solution, the apparent resting membrane potential of odontoblasts was determined to be -24 +/- 4 mV (mean +/- SE), whereas the odontoblast intracellular pH was found to be 6.66 +/- 0.02. The values obtained are within the range of other cell types, as measured in similar incubating solutions. The pH in the extracellular predentin was higher than the intracellular pH, 7.00 +/- 0.02. The Ca2+ ion activity in predentin (pCa = 2.94 +/- 0.15) was found to be significantly (P less than 0.001) higher than that in the dental pulp extracellular fluid (pCa = 3.37 +/- 0.14). The 2-3 times higher calcium activity extracellularly in predentin, compared with the dental pulp, implies the existence of some ion-concentrating mechanism across the odontoblast layer in the direction of the mineralization front.

Animals↗
PubMed1992

Calcium ion transport kinetics during dentinogenesis: effects of disrupting odontoblast cellular transport systems.

Due to strongly discrepant results in the literature, controversy exists about the timing of the transport of Ca2+ ions to the mineralization front during dentinogenesis and the role of the odontoblasts in this transport. The present study gives evidence, by means of autoradiography as well as by a radiochemical technique, that the transport time for Ca2+ ions into the dentin mineral phase is about 10-15 min in the rat incisor. The results also show that technical factors, such as mode of tracer injection and the use of perfusion fixation, may influence the results more or less strongly. Finally, by disturbing odontoblast microtubules, involved in intracellular transport processes, and by blocking odontoblast calcium uptake channels by nifedipine and neomycin, the Ca2+ ion transport into dentin mineral was found to be strongly impaired. This may be taken as an indication that transcellular calcium transport mechanisms have a role during dentinogenesis.

Animals↗
PubMed1992

Calcium transport in dentinogenesis. An experimental study in the rat incisor odontoblast.

Since cellular calcium transport mechanisms during biological calcification are less known, a series of experiments were performed by in vivo as well as in vitro methodologies in the dentinogenically active rat incisor. By means of micro-electrode technique, the pH and pCa (calcium ion activity) in predentin in situ were found to be 7.0 and 2.9, respectively. It was concluded that there exists a Ca2+ion concentrating mechanism over the odontoblast layer in direction towards the mineralization front. The kinetics of this calcium flow was determined in vivo by radiotracer technique. The time for 45Ca2+ uptake into the dentin mineral phase was determined to 10-15 min. Transmembraneous Ca2+ ion pumps and channels in odontoblasts were further analyzed. The resting membrane potential of rat incisor odontoblasts was determined to -24 mV. Using ion-specific mini-electrode technique as well as fluorescence spectrophotometry, calcium channels, Ca(2+)-ATPase and Na+/Ca2+ antiports, responsible for cellular Ca2+ uptake and extrusion, were identified in the odontoblast plasma membrane. Dissected odontoblasts were subjected to subcellular fractionation. An electrophoretic uniporter and a Na2+/Ca2+ exchanger, for Ca2+ release and uptake, respectively, were demonstrated in mitochondria, whereas a Ca(2+)-ATPase was present in the microsomal fraction. Mitochondria, microsomes and whole, digitonin-permeabilized odontoblasts, were able to maintain a steady state Ca2+ activity at pCa = 6.4-6.6 in vitro. In rats treated with colchicine, the incorporation of 45Ca2+ into dentin mineral was severely altered. Similarly, administration to rats of specific calcium channel blockers strongly inhibited 45Ca2+ incorporation. Together, the results indicate that a transcellular pathway is a major route for Ca2+ ion transport during dentinogenesis, and that this may be under a relatively strict cellular control.

Animals↗
PubMed1991

Retrospective study of children with hypophosphatasia with reference to dental changes.

In the present retrospective study different dental and medical parameters have been analyzed in 17 Swedish children with established hypophosphatasia (HP). It was demonstrated that the basis for the establishment of the diagnosis varied among different dentists and physicians, and that the diagnostic parameters studied among the children varied. The most reliable parameters for HP included raised levels of phosphoethanolamine in urine, and clinical and radiologic findings associated with the legs. These findings were found among the children more often than lowered values of alkaline phosphatase in serum. Histologic analysis of an extracted tooth made a valuable diagnostic complement. It is concluded that a better diagnostic uniformity is recommended. In a well functioning collaboration with well defined tasks, both dentists and physicians can contribute to a reliable diagnosis.

Adolescent↗
PubMed1990

High-performance liquid chromatography of sialic acid-containing oligosaccharides and acidic monosaccharides.

Many sialic acid-containing oligosaccharides and five acidic monosaccharides have been separated by high-performance anion-exchange chromatography using a Dionex AS6 ion-exchange column eluted with aqueous 50 mM NaOH plus 50-175 mM sodium acetate. Using a pulsed amperometric detector, as little as 50 pmol oligosaccharide can be detected. Many factors, such as the presence of fucosyl groups or sialyl groups, glycosidic linkage positions, and branching structure, can have a tremendous influence on overall acidity of the oligosaccharide, which can lead to excellent separations and make this method an important addition to existing alternatives for the separation of sialic acid-containing oligosaccharides.

Carbohydrate Sequence↗
PubMed1990

Isolation and structural analysis of three new disialylated oligosaccharides from human milk.

Five disialylated oligosaccharides, of which three were new compounds, were isolated from pooled human milk. The isolation procedure included gel filtration and ion-exchange chromatography and the final purification was accomplished by HPLC using a mobile phase containing triethylamine as an ion-pairing reagent. Structural analysis was carried out by chemical analyses, fast atom bombardment mass spectrometry, and 500-MHz NMR spectroscopy. The following new structures were found: (formula; see text).

Carbohydrate Conformation↗
PubMed1990

Separation of non-collagenous proteins of bone formed in titanium implants: experimental study in the rabbit tibia, using a bone harvest chamber.

The non-collagenous proteins of mature cortical rabbit bone and 3 wk old bone specimens formed in titanium implant bone harvest chambers, were separated by means of fine pressure liquid chromatography. It was found that a sufficient amount of bone could be obtained from five bone harvest chambers in five rabbits during a period of 15 wk. A different protein chromatographic pattern was found in bone grown in bone harvest chambers as compared to normal cortical bone from the same region. This indicates a difference in bone quality and shows that this implant design can be used for biochemical analysis of bone formed adjacent to a biomaterial.

Animals↗
PubMed1990

Calcium transport in dentinogenesis.

A fundamental question in biomineralization research is the metabolism of the ionic constituents of the mineral phase. Mechanisms for the transport of Ca2+ ions have been identified and characterized in detail for various types of cells. Surprisingly little is known about osteoblasts and odontoblasts in this respect. This paper reviews what is known about calcium metabolism during dentinogenesis.

Animals↗
PubMed1989

Isolation of monosialyated oligosaccharides from human milk and structural analysis of three new compounds.

The monosialyated oligosaccharide fraction from combined samples of human milk was fractionated by gel filtration, ion-exchange chromatography, and h.p.l.c. with triethylamine as an ion-pairing reagent. Among the twelve oligosaccharides isolated, three were new compounds for which the following structures were established on the basis of chemical analyses, f.a.b.-m.s., and n.m.r. spectroscopy.

Carbohydrate Conformation↗
PubMed1988

Na+/Ca2+ antiports in membranes of rat incisor odontoblasts.

When incubated in the presence of Na+ ions, dissected rat incisor odontoblasts extruded Ca2+ ions, as detected by tetracycline fluorimetry. Also odontoblast mitochondria, obtained by subcellular fractionation and monitored by ion-specific mini-electrode technique, were found to extrude Ca2+ upon addition of Na+ ions. These findings demonstrate the presence of Na+/Ca2+ antiports in the odontoblast plasma membrane as well as in the odontoblast mitochondrial inner membrane. In addition, evidence was found for an ATP-dependent Ca2+ ion extrusion across the plasma membrane in these cells.

Adenosine Triphosphate↗
PubMed1988

Elemental imaging of dental hard tissues by secondary ion mass spectrometry.

High resolution imaging by secondary ion mass spectrometry (SIMS) has been employed in a chemical-microstructural pilot study of different classes of hard tissues from human and rat. The special scanning ion microprobe instrumentation permitted the recording of element-resolved images with a lateral resolution of about 50 nm. Sharp distribution micrographs were obtained for Ca+, F- and CN-, and in selected specimens for Na+, K+, Mg+, O-, Cl-, C- and PO-. Several trends in the elemental kinetics of mineralization were comprehensively illustrated and new aspects were indicated. The paper points out the broad scope of interest, and the potentialities of unique applications, in SIMS imaging of biomineralized tissues, the conditions for efficient employment of the recently developed technique are briefly discussed and demonstrated.

Animals↗
PubMed1987

Regulation of free Ca2+ by subcellular fractions of rat incisor odontoblasts.

A miniaturized Ca2+ electrode system was developed to monitor small and fast fluctuations of Ca2+ activity in the micromolar range in 100 microliters volumes. This was used to study Ca2+ influx/efflux cycling in suspensions of rat-odontoblast and liver-cell mitochondria and microsomes, as well as in whole odontoblasts with plasma membranes made permeable by digitonin. The steady-state free-Ca2+ activity maintained by mitochondria was pCa 6.2-6.4, and that of microsomes pCa 6.4-6.6. These levels were held upon repeated additions of Ca2+ and EGTA. The odontoblast mitochondria and microsomes had an intracellular Ca2+ buffering capacity similar to that of liver cells. The steady-state pCa level maintained in suspensions of digitonin-permeabilized whole odontoblasts was 6.4-6.6. Thus, this study gave no evidence for any specialized intracellular handling of Ca2+ in cells involved in mineralization.

Animals↗
PubMed1986

Epitope specificity and cross-reactivity pattern of a large series of monoclonal antibodies to carcinoembryonic antigen.

Monoclonal antibodies (MAbs) were produced against purified carcinoembryonic antigen (CEA) from liver metastases of colo-rectal and lung adenocarcinoma. Three and eight anti-CEA MAbs from the two groups were analyzed in detail. All antibodies were IgG1. With one exception they recognized epitopes present on all eight individual CEA preparations investigated irrespective of whether they were from colo-rectal or lung carcinoma. The exceptional MAb reacted with an epitope present on most but not all CEA preparations. With two, or possibly three, exceptions the MAbs recognized conformation dependent epitopes in the peptide moiety of CEA. One MAb reacted strongly with reduced and carboxymethylated CEA but only weakly with native CEA. Four MAbs appeared to be CEA-specific in that they did not react with any of the known CEA-cross-reactive substances including nonspecific cross-reactive antigen of 160,000 mol. wt (NCA-160). A total of nine different epitopes were detected in native CEA using this and our previous series [Hedin A., Hammarström S. and Larsson A. (1982) Molec. Immun. 19, 1641] of anti-CEA MAbs. With one exception practically all molecules (70-90%) in purified CEA preparations contained these epitopes.

Antibodies, Monoclonal↗
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↗