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Biomedical subjects

J Mattson

Publications and source records attributed to J Mattson.

At least 19 recordsLinked to original sources
PubMed2000

An investigation of the dynamics of aggression: direct observations in ice hockey and basketball.

There have been significant problems in the study of sports aggression, and they are linked to how aggression has been defined, measured, and analyzed. Following a review of the whole domain, this study aimed to construct a theoretically coherent and ecologically valid framework for research on processes underlying sports aggression and to contribute to the advancement of knowledge in the area. An exploratory method using computer observational analysis as the primary research method, along with complementary questionnaires and personal reflections, considered aggression in two comparison sports: ice hockey and basketball. Data were compiled and classified by involved and independent experts relative to factors and behaviors associated with sports aggression derived from a comprehensive review of the literature. Among the study's findings were that: (a) aggression was instrumental in nature two-thirds of the time; (b) aggressive acts typically occurred in clusters and varied in frequency according to game circumstances; and (c) multiple variables and aggression theories were related to severely aggressive acts. The complex dynamics of sports aggression via similar naturalistic methodologies is discussed.

Adolescent↗
PubMed2000

Formation of an interfering substance, 3,4-dimethyl-5-phenyl-1,3-oxazolidine, during a pseudoephedrine urinalysis.

During fatal aviation accident investigations, biosamples from the victims are submitted to the FAA Civil Aeromedical Institute (CAMI) for drug analysis. In the process of one such analysis by CAMI, an unknown substance was found in a urine sample. Simultaneous screening by thin layer chromatography (TLC) and gas chromatography/FID (GC/FID) suggested the presence of pseudoephedrine. A subsequent routine confirmation analysis of a separate urine aliquot by GC Fourier transform infrared (GC/FTIR) and GC mass spectrometry (GC/MS) indicated that the retention times of the unknown substance matched with those of pseudoephedrine. However, its infrared and mass spectra were different--the -OH and -NH groups were missing, a C-O-C group was present, and the molar mass was 12 atomic mass units (amu) more than that of pseudoephedrine. A subsequent literature search suggested that ephedrine-like amines react with aldehydes to form oxazolidines. Therefore, the 12-amu increase could be accounted for by condensation of pseudoephedrine with formaldehyde. Since this aldehyde is present in various grades of methanol and ethyl acetate, and these solvents were used during the solid-phase extraction, 3,4-dimethyl-5-phenyl-1,3-oxazolidine was synthesized by using (+)-pseudoephedrine HCl and formaldehyde. The analytical findings of the synthesized compound were consistent with those of the unknown interfering substance, confirming that it was the oxazolidine. Aldehyde contaminants in solvents or specimens can transform drugs of interest and may result in misidentification of a compound originally present in specimens. Therefore, chemicals used in analyses should be of the highest available purity, and a multi-analytical approach should be adopted to maintain a high degree of quality assurance.

Accidents, Aviation↗
PubMed1998

Forms of communication: a cross-cultural comparison of older married couples in the USA and Japan.

Interviews were conducted with 24 older couples in the USA and Japan. Spouses participated in a causal conversation during which they discussed their marital history. The dialogue between the spouses was examined in relation to five forms of communication: prompting, questioning, echoing, contradicting, and teasing. Results from this analysis challenge some of the stereotypes concerning Japanese and American communication patterns. Couples in both countries engaged in teasing but the purpose of these kinds of exchanges differed for the American and the Japanese spouses. Findings are discussed in relation to cultural and gender differences and similarities in forms of communication between older spouses.

Journal Article↗
PubMed1996

Biochemical and genetic characterization of multiple splice variants of the Flt3 ligand.

We have performed a comprehensive analysis of cell lines and tissues to compare and contrast the expression patterns of Flt3 ligand (FL), c-Kit ligand (KL), and macrophage colony-stimulating factor as well as their receptors, Flt3, c-Kit, and c-Fms. The message for FL is unusually ubiquitous, whereas that of its receptor is quite restricted, apparently limiting the function of the ligand to fetal development and early hematopoiesis. We have also sequenced a mouse FL genomic clone, revealing how the three splice variant FL mRNAs that we have isolated arise. The chromosomal location of the FL gene has been mapped, by in situ hybridization, to chromosome 7 in mouse and chromosome 19 in human. Natural FL protein has been purified from a stromal cell line and shown to be a 65 kD nondisulfide-linked homodimeric glycoprotein comprised of 30 kD subunits, each containing 12 kD of N- and O-linked sugars. Pulse-chase experiments show that one of the splice variants (T110) is responsible for producing the bulk of soluble FL, but only after it has first been expressed at the cell surface as a membrane-bound form. The other splice-variant forms produce molecules that are either obligatorily soluble (T169) or membrane-bound but released only very slowly (T118). Finally, even though most cell lines express some amount of FL mRNA, we found that very little FL protein is actually made, with T cells and stromal cells being the major producers. The data suggests that FL plays its roles over very short distances, perhaps requiring cell-cell contact.

Amino Acid Sequence↗
PubMed1996

CD94 and a novel associated protein (94AP) form a NK cell receptor involved in the recognition of HLA-A, HLA-B, and HLA-C allotypes.

Whereas the human killer cell inhibitory receptors (KIRs) for HLA class I are immunoglobulin-like monomeric type I glycoproteins, the murine Ly49 receptors for H-2 are type II homodimers of the C-type lectin superfamily. Here, we demonstrate that human NK cells also express C-type lectin receptors that influence recognition of polymorphic HLA-A, HLA-B, and HLA-C molecules. These receptors are heterodimers composed of CD94 chains covalently associated with novel tyrosine-phosphorylated glycoproteins (94AP). Some NK clones recognize a common HLA-C ligand using both KIRs and CD94-94AP receptors. These findings suggest the existence of human inhibitory MHC class I receptors of the immunoglobulin and C-type lectin superfamilies and indicate overlap in ligand specificity.

Adult↗
PubMed1994

B7 and interleukin 12 cooperate for proliferation and interferon gamma production by mouse T helper clones that are unresponsive to B7 costimulation.

We have previously shown that dendritic cells isolated after overnight culture, which can express B7 and are potent stimulators of naive T cell proliferation, are relatively poor at inducing the proliferation of a panel of murine T helper 1 (Th1) clones. Maximal stimulation of Th1 clones was achieved using unseparated splenic antigen presenting cells (APC). An explanation for these findings is provided in the present study where we show that FcR+ L cells transfected with B7 stimulate minimal proliferation of Th1 clones in response to anti-CD3 antibodies, in contrast to induction of significant proliferation of naive T cells. However, addition of interleukin 12 (IL-12) to cultures of Th1 cells stimulated with anti-CD3 and FcR+ B7 transfectants resulted in a very pronounced increase in proliferation and interferon gamma (IFN-gamma) production. Exogenous IL-12 did not affect the B7-induced proliferation of naive T cells. This showed that whereas costimulatory signals delivered via B7-CD28 interaction are sufficient to induce significant proliferation of naive T cells activated through occupancy of the T cell receptor, Th1 T cell clones require cooperative costimulation by B7 and IL-12. This costimulation was shown to be specific by inhibition of proliferation and IFN-gamma production using chimeric soluble cytolytic T lymphocyte-associated antigen 4-human IgG1Fc (CTLA4-Ig) and anti-IL-12 antibodies. Furthermore, the significant antigen specific proliferation and IFN-gamma production by Th1 clones observed when splenocytes were used as APC was almost completely abrogated using CTLA4-Ig and anti-IL-12 antibodies. Thus two costimulatory signals, B7 and IL-12, account for the ability of splenic APC to induce maximal stimulation of Th1 clones. IL-10 downregulates the expression of IL-12 by IFN-gamma-stimulated macrophages and this may account largely for t the ability of IL-10 to inhibit APC function of splenic and macrophage APC for the induction of Th1 cell proliferation and IFN-gamma production. Indeed we show that IL-12 can overcome the inhibitory effect of IL-10 for the APC-dependent induction of proliferation and IFN-gamma production by Th1 clones. These results suggest that proliferation by terminally differentiated Th1 clones, in contrast to naive T cells, requires stimulation via membrane-bound B7 and a cytokine, IL-12. It is possible that these signals may result in the activation of unresponsive T cells during an inflammatory response. IL-10, by its role in regulating such innate inflammatory responses, may thus help to maintain these T cells in an unresponsive state.

Abatacept↗
PubMed1994

Ligand for FLT3/FLK2 receptor tyrosine kinase regulates growth of haematopoietic stem cells and is encoded by variant RNAs.

The FLT3/FLK2 receptor tyrosine kinase is closely related to two receptors, c-Kit and c-Fms, which function with their respective ligands, Kit ligand and macrophage colony-stimulating factor to control differentiation of haematopoietic and non-haematopoietic cells. FLT3/FLK2 is thought to be present on haematopoietic stem cells and found in brain, placenta and testis. We have purified to homogeneity and partially sequenced a soluble form of the FLT3/FLK2 ligand produced by mouse thymic stromal cells. We isolated several mouse and human complementary DNAs that encode polypeptides with identical N termini and different C termini. Some variants contain hydrophobic transmembrane segments, suggesting that processing may be required to release soluble ligand. The purified ligand enhances the response of mouse stem cells and a primitive human progenitor cell population to other growth factors such as interleukins IL-3 and IL-6 and to granulocyte-macrophage colony-stimulating factor, and also stimulates fetal thymocytes.

Amino Acid Sequence↗
PubMed1994

Effects of pulp mill chlorate on Baltic Sea algae.

The long-term effects of pulp mill chlorate on different algal species of the Baltic Sea were studied in land-based model ecosystems simulating the littoral zone. Brown algae (Phaeophyta) exhibited an extraordinarily high sensitivity to chlorate and pulp mill effluents containing chlorate. All brown algal species ceased growth or showed major signs of toxicity at all concentrations tested, down to microgram per litre levels. EC50 levels for growth of Fucus vesiculosus were about 80-100 microg ClO3- litre(-1). Blue-green algae (Cyanophyta) were not deleteriously affected nor were green algae (Chlorophyta). The perennial and annual species of red algae (Rhodophyta) were also unaffected by the effluents. Diatoms did not show any sensitivity and phytoplankton (fresh- and brackish water) were particularly insensitive. A phanerogam, Zostera marina was also unaffected by the treatments.

Journal Article↗
PubMed1990

Evaluation of blood flow measurements with microspheres and rubidium--an experimental study in rats.

The microsphere method has been widely used for blood flow measurements in normal and tumour tissues. The microsphere method was evaluated for repeated measurements of cardiac output and regional blood flow in anesthetised rats and in anesthetised rats given noradrenalin and thereby having altered haemodynamics with special emphasis on liver blood flow. Comparing the microsphere method with the soluble indicator method (86Rubidium) gave equal cardiac output values. The liver blood flow was lower and the spleen blood flow was higher with the microsphere method. Two microsphere injections at 10 min intervals were performed on anesthetised rats. In one group 817 +/- 10(3) microspheres were injected each time, in a second group 436 +/- 10(3) and in a third noradrenalin was added and then 430 +/- 10(3) microspheres injected twice. There was good reproducibility for cardiac output and for most organ and tissue blood flows between first and second microsphere injection. No influence on arterial liver blood flow was seen. A blood pressure fall and a decreased heart rate was registered after the first injection in the group given 817 x 10(3) spheres. There was also a blood pressure fall in the group given noradrenalin after the first microsphere injection. The microsphere method with two injections of 436 x 10(3) microspheres seems adequate to use in arterial blood flow studies of the liver and simultaneous cardiac output measurements.

Animals↗
PubMed1984

Vasoactive drugs and tumor blood flow.

Different observations on the reactivity of tumor vessels to vasoactive drugs have suggested a decreased, a similar or an increased reactivity to vasoactive stimuli in the vascular bed of tumors as compared to normal tissues. No adrenergic innervation of newly developed tumor vessels has been found, while preexisting normal vessels incorporated during tumor growth may retain some innervation. In transplantable rat tumors, contractile cells, including smooth muscle cells, have been seen in tumor vessels. From recent experimental studies, it was concluded that the tumor's vascular bed is probably in a state of maximal dilatation and therefore sensitive to vasoconstriction, but less sensitive to pharmacological dilatation. These observations may correspond to regional tumor hypoxia and progressive development of tumor necrosis during tumor growth. The results of experimental tumor studies might question the reliability of diagnostic and therapeutic procedures in clinical oncology, which are based on differences in the reactivity to vasoactive drugs between normal and malignant tissues.

Adrenergic Fibers↗
PubMed1981

Tyrosinase subcellular distribution and kinetic parameters in wild type and C-locus mutant C57BL/6J mice.

The distribution and kinetic parameters of tyrosinase (EC 1.14.-18.1) from anagen hair follicles of the C57BL/6J mouse and several c-locus mutants were investigated. The results showed that c-locus mutations not only influenced the total tyrosinase activity, but the subcellular distribution as well. The kinetic parameters of tyrosinase were not influenced by the pigment mutations, suggesting that the mutations were not influencing the structure of the enzyme.

Animals↗
PubMed1980

Factor VII inhibitor.

Factor VII inhibitor activity was identified in a 66 year old man with probable bronchogenic carcinoma. Initial studies indicated a normal partial thromboplastin time (PTT) and a prothrombin time (PT) prolongation which increased with incubation. PT correction failed to occur with 50 per cent normal plasma in vitro and 2 U of fresh frozen plasma in vivo, indicating inhibitor activity. Specific factor assay levels fell within normal limits except for a factor VII level of 30 per cent. Subsequent evaluation with antiglobulin studies suggested an inhibitor of immunoglobulin G [IgG] origin.

Aged↗