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Biomedical subjects

U Larsson

Publications and source records attributed to U Larsson.

At least 19 recordsLinked to original sources
PubMed2003

Parallel DNA template preparation using a vacuum filtration sample transfer device.

Solid-phase techniques have facilitated the handling of biochemical analytes. This has stimulated the development of systems by which large sample panels can be analyzed with high levels of security and quality. We describe a sample transfer device based on the principle of vacuum filtration, which enables parallel handling of 96 samples of analytes bound to Sepharose beads. The tool was employed for strand separation of DNA samples, by attracting the beads to filter probes while passing them between the reagent solutions. The samples were analyzed using Pyrosequencing technology and proved to yield genotyping results of high quality. The presented sample preparation procedure provides an important link in the development of integrated systems for rapid genetic analysis at a low cost. In addition, the same filter could be reused extensively with very low risk for detectable cross-contamination between assays and without any reduction in processing capacity, thus further reducing the cost per analyzed sample.

DNA↗
PubMed2002

Impact of overweight and obesity on health-related quality of life--a Swedish population study.

OBJECTIVE: To investigate the impact of overweight and obesity on health-related quality-of-life (HRQL) in the general population in western Sweden. DESIGN: Cross-sectional survey. SUBJECTS: A total of 5633 men and women aged 16-64 y born in Sweden. MAIN OUTCOME MEASURES: Scale and summary component scores of the SF-36 Health Survey. RESULTS: Obese men aged 16-34 y rated their HRQL lower than normal-weight men did on all four physical health scales of the SF-36 and on two of the four mental health scales. Obese women in the same age group rated their health worse than normal-weight women on three of the physical health scales. Thus, in younger men and women the analysis indicated a clearer negative association between obesity and physical health than between obesity and mental health. Obese women aged 35-64 y rated their health worse on all scales than normal-weight women did, while obese men in this age group rated their health worse on only two SF-36 subscales-physical functioning and general health perception. The massively obese men and women suffered from a poor level of HRQL. CONCLUSION: Not only does the level of obesity affect HRQL, the impact of overweight and obesity also differs by age and sex. The importance of aspects of both physical and mental health should be fully recognised.

Adolescent↗
PubMed2001

Nitrogen and the Baltic Sea: managing nitrogen in relation to phosphorus.

The Baltic is a large, brackish sea (4 x 10(5) km2) extending from 54N to approximately 66N, with a fourfold larger drainage area (population 8 x 10(7). Surface salinity (2 to 8 PSU) and hence biodiversity is low. In the last century, annual nutrient loads increased to 10(6) metric tons N and 5 x 10(4) ton P. Eutrophication is evident in the N-limited south, where cyanobacteria fix 2 to 4 x 10(5) ton N each summer, Secchi depths have been halved, and O2-deficient bottom areas have spread. Production remains low in the P-limited north. In nutrient-enriched coastal areas, phytoplankton blooms, toxic at times, and filamentous macroalgae reduce amenity values. Loads need to be reduced of both N, to reduce production, and P, to limit N-fixing cyanobacterial blooms. When large N-load reductions have been achieved locally, algal biomass has declined. So far, P loads have been reduced more than N loads. If this continues, a P-limited Baltic proper may result, very different from previous N-limited conditions. Reaching the management goal of halved anthropogenic N and P loads at minimum cost will require better understanding of biogeochemical nutrient cycles, economic evaluation of proposed measures, and improved stakeholder participation.

Environment↗
PubMed2001

Mast cells express functional CD30 ligand and are the predominant CD30L-positive cells in Hodgkin's disease.

Hodgkin's disease (HD) tumours are characterized by the presence of few tumour cells, the Hodgkin and Reed-Sternberg (HRS) cells, surrounded by a large amount of non-neoplastic cells. The role of this cell infiltrate for the development of HD is not known. CD30, belonging to the tumour necrosis factor receptor superfamily, is highly expressed on HRS cells and believed to be involved in tumourigenesis and tumour progression. Tumour samples from 42 patients were immunohistochemically double-stained for tryptase, a mast cell-specific proteinase and CD30 ligand (CD30L). Tryptase-positive mast cells were present in all tumours. Of these cells, 50% expressed CD30L and 66% of the CD30L-positive cells were mast cells. CD30L mRNA in in vitro developed normal mast cells and malignant human and murine mast cell lines was detected using reverse transcription polymerase chain reaction. CD30L protein expressed on human mast cells was detected using flow cytometry. In a co-culture assay, the human mast cell line HMC-1 stimulated thymidine uptake in HRS cell lines, and the stimulation could be blocked using CD30L-specific monoclonal antibodies. In conclusion, mast cells are present in HD tumours and are the predominant CD30L-expressing cells. CD30L-CD30 interaction is a pathway by which mast cells may stimulate DNA synthesis in HRS cells.

Adult↗
PubMed1998

Activated transcription of the human neuropeptide Y gene in differentiating SH-SY5Y neuroblastoma cells is dependent on transcription factors AP-1, AP-2alpha, and NGFI.

Activated transcription of the human neuropeptide Y gene (NPY) was investigated in SH-SY5Y neuroblastoma cells at the onset of sympathetic neuronal differentiation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) and serum or by nerve growth factor (NGF). As determined by transient expression, two NGF response elements (REs) were required for transcription induced by NGF in SH-SY5Y cells with stable expression of an exogenous NGF receptor TRK-A gene (SH-SY5Y/trk). TPA treatment in the presence of serum induced NPY transcription in both wild-type SH-SY5Y (SH-SY5Y/wt) and SH-SY5Y/trk cells. A TPA RE (TRE), overlapping the proximal NGF RE, was identified by expression of the v-Jun oncoprotein that enhanced NPY transcription. Suppression of TPA-induced NPY transcription was obtained by expression of a dominant negative Jun protein, selective protein kinase C inhibition, or introduction of a mutated TRE, whereas NGF-induced NPY transcription was inhibited to a lesser degree. The transcription factor AP-2alpha was shown to bind cooperatively to the NPY promoter with either AP-1 or NGFI-A to the shared TRE and NGF RE and to the distal NGF RE, respectively. These results show that transcription factors AP-1, AP-2alpha, and NGFI-A are involved in activated NPY transcription during the onset of neuronal differentiation.

Base Sequence↗
PubMed1997

Two non-racemic preparations of a piperidine-based NMDA antagonist with analgesic activity.

(2R,3S,1'R)-3-(1-Hydroxy-2-phosphonoethyl)-2-piperidinecarboxyl ic acid 1 has been synthesized by two different methods. The NMDA receptor binding affinities (Ki values) are 74 nM for compound 1, and 64 nM for the corresponding ketone 2. The analgesic effects were evaluated using the mouse hot-plate test and the mouse formalin model. The ED50 values for the racemates of compounds 1 and 2, using the mouse hotplate and intrathecal injection, were 0.53 and 0.51 nmol, respectively.

Analgesics↗
PubMed1995

Differentiation and survival influences of growth factors in human neuroblastoma.

Human neuroblastoma cell lines are established from high-stage, highly malignant tumours. Despite this and the fact that these tumours are arrested at an early, immature stage, many cell lines have the capacity to undergo neuronal differentiation under proper growth conditions. One such cell line is the noradrenergic SH-SY5Y cell line. These cells can be induced to mature by a variety of modalities, resulting in different mature phenotypes. The use of this cell system as a model to study the stem cell character of neuroblastoma is reviewed and discussed. In particular, we focus on growth factor dependencies in the SH-SY5Y system, and compare that to the normal situation, i.e. growth factor control of sympathetic neuronal and neuroendocrine differentiation during human and rat embryogenesis.

Cell Differentiation↗
PubMed1991

A sensitive method for measuring neutralizing antibodies to Bordetella pertussis toxin: optimized ADP-ribosylation of transducin.

Pertussis toxin (PT), preactivated with 20 mm dithiothreitol (DTT), was incubated with different serum dilutions (1/10-1/200) before addition to the reaction mixture. Final concentrations of the reagents were: PT (50 ng/ml), dithiothreitol (DTT)(less than or equal to 0.3 mM), bovine transducin (2 micrograms/ml), ATP (1 mM). GTP (1 mM), lysophosphatidylcholine (LTC) (0.1 mg/ml), sodium acetate (NaAc) (0.1 M), Tris-HCl, pH 7.1 (0.06 M) and 32P-NAD+ (10 microCi 28 Ci/mM). The reaction was stopped by precipitation with 10% TCA (w/v), the pellet was collected and the samples were submitted to SDS-PAGE followed by autoradiography. ADP-ribosylation was detected as the radiolabelling of a protein band (m.w. approximately 40 kD) corresponding to the alpha-subunit of transducin. 32P-ADP incorporation was a linear function of PT concentration. By this assay quantitative differences in PT neutralizing antibodies were found between sera which were not revealed by measuring PT neutralizing antibodies by a Chinese hamster ovary (CHO) cell culture test or by an enzyme-linked immunosorbent assay (ELISA). The conditions of the ADP-ribosylation of bovine transducin have been optimized to permit detection of the enzymic activity of as low amounts of PT as 0.5 ng. This opens the possibility of the study of the presence and avidity of neutralizing antibodies to PT in post-vaccination sera without preceding purification and concentration of the antibodies and thus may provide a useful tool for evaluation of whooping cough vaccines.

Adenosine Diphosphate Ribose↗
PubMed1991

Protective immunogenicity of synthetic peptides selected from the amino acid sequence of Bordetella pertussis toxin subunit S1.

Five synthetic peptides identified as antigenic sites on the S1 subunit of pertussis toxin (PT) were coupled to the diphtheria toxin cross-reactive mutant protein CRM 197 or BSA. All peptide conjugates were immunogenic in animals. Two peptide-CRM-conjugates, corresponding to amino acids 1-17 and 169-186, induced especially high antibody titers against native PT in mice (Balb/c, C57/Black and outbred NMRI) as measured by ELISA. Upon in vivo PT challenge (0.5 microgram toxin) of the NMRI mice both the CRM and BSA conjugates of these two peptides fully protected the mice from PT induced leucocytosis. Some of the protected mice receiving peptide 1-17 conjugate had very low antibody titers against PT but high titers against the peptide as measured by ELISA, showing that PT-ELISA does not always reflect in vivo protection. A booster response against PT was noted upon challenge with PT in mice receiving peptide 1-17 or peptide 169-186 conjugate. Antibodies against peptide 170-186 could not be evaluated by ELISA since conjugates of this peptide (like PT itself) bind to immunoglobulins. They may also caused clustering of CHO cells. Rabbit antiserum to the peptide 1-17-CRM conjugate was highly efficient in inhibiting the ADP-ribosylating activity of PT with bovine transducin as substrate whereas the rabbit antiserum raised against the peptide 169-186-CRM conjugate neutralized the clustering effect of PT on CHO cells. Thus there is no concise correlation between the in vivo protection against PT challenge and the in vitro methods used for measuring antibody levels against PT (neutralization of the enzyme activity, the CHO cell clustering activity and titers in PT-ELISA). The CRM-conjugates of these two peptides constitute the first synthetic pertussis vaccine candidate with the ability to provide a chemically well defined, safe and efficient pertussis vaccine.

Amino Acid Sequence↗
PubMed1990

Protective immunogenicity of two synthetic peptides selected from the amino acid sequence of Bordetella pertussis toxin subunit S1.

Two peptides, corresponding to amino acids 1-17 and 169-186 of the amino acid sequence of pertussis toxin (PT) subunit S1, were synthesized and coupled to the diphtheria toxin cross-reactive mutant protein CRM 197 and evaluated for immunogenicity and protective capacity against PT challenge in vivo. The peptide-CRM conjugates induced high antibody titers against native toxin in mice (BALB/c, C57/Black, and outbred NMRI) as measured by ELISA. Upon PT challenge (0.5 microgram of toxin) of the NMRI mice, the CRM conjugates of peptides 1-17 and 169-186 fully protected the mice from PT-induced leukocytosis. Immunization with the corresponding bovine serum albumin conjugates of these two peptides also fully protected mice. Rabbit antiserum to the peptide 1-17-CRM conjugate was highly efficient in inhibiting the ADP-ribosylating activity of PT but did not neutralize the clustering effect of PT on Chinese hamster ovary cells. In contrast, the rabbit antiserum raised against the peptide 169-186-CRM conjugate neutralized the clustering effect of PT on Chinese hamster ovary cells but did not inhibit the enzymatic activity of PT. Peptide 169-186-CRM conjugates mimic the immunoglobulin binding properties of PT and also cause clustering of Chinese hamster ovary cells. The CRM conjugates of these two peptides constitute a synthetic pertussis vaccine candidate with the ability to provide a chemically well-defined, safe, and efficient pertussis vaccine.

Amino Acid Sequence↗
PubMed1988

Polymerization and gelation of fibrinogen in D2O.

The solution properties of fibrinogen and the thrombin-induced activation and gelation of fibrinogen in 95% D2O at pH 7.4 were compared to those in H2O under similar conditions. The initial release rates of fibrinopeptides A and B in D2O were slightly slower than those in H2O. However, the values of the Michaelis-Menten parameters Km and V for the release of the two peptides in D2O and H2O in the presence of 0.5 M NaCl were about the same. From turbidity measurements at 450 nm it is obvious that fibrinogen is soluble in a slightly more narrow range of NaCl concentration and that the fibrin gels have a higher degree of lateral aggregation in D2O than in H2O. The variation of fibrinogen concentration, thrombin concentration, pH and ionic a strength have a similar dependence on the final gel structure and clotting time in D2O and H2O. SDS-gel electrophoresis on fibrin samples, which were cross-linked by factor XIII, yielded results where the cross-linking of the gamma-chain appeared to be the same in D2O and H2O. The alpha-chain cross-linking was somewhat faster in D2O than in H2O. When fibrinogen solutions in 95% D2O were incubated at 20 mM CaCl2, a slow gelation of fibrinogen was observed, which was found to be induced by trace amounts of factor XIII. The final gel turbidity appeared to be about the same for this gelation as for that induced by thrombin. The differences in solubility for fibrinogen, kinetics for the enzyme reaction and optical properties for the fibrin gels in D2O and H2O may be explained by differences in electrostatic interactions, hydrogen bonding and hydration of fibrinogen in these two media.

Calcium Chloride↗
PubMed1988

Structure analysis of fibrinogen by electron microscopy and image processing.

Human fibrinogen was observed by electron microscopy following rotary shadowing with tungsten. Structure analysis of the molecules was performed by image processing of electron micrographs. A method is described for selection, alignment, and classification of molecules. The widely accepted overall trinodular structure of the protein was observed. The flexibility about the central domain of the molecule was quantitatively analyzed. A Gaussian distribution of this conformational parameter was obtained having an average corresponding to a maximally extended structure. Correspondence analysis applied to the aligned images showed that the degree of folding of the molecule was continuously distributed. The averaged structure of fibrinogen was estimated to be 450 A long. The central domain had a diameter of 50 A and the peripheral domains were 90 A long and 50 A wide. The latter regions had two separated maxima of scattering density.

Fibrinogen↗
PubMed1987

Base pair opening dynamics of a 2-aminopurine substituted Eco RI restriction sequence and its unsubstituted counterpart in oligonucleotides.

Studies of 1H NMR selective saturation recovery were performed to determine the imino proton exchange with solvent water of the base pairs in the Eco RI endonuclease recognition sequence GAATTC, placed at the center of self-complementary decamer and dodecamer oligonucleotides. In one oligonucleotide the innermost adenine was replaced by the fluorescent base analogue 2-aminopurine (2AP). From the measurements at different concentrations of TRIS buffer acting as proton exchange catalyst, base pair lifetimes were evaluated. The results at 25 degrees show that the AT base pairs have lifetimes of the order of a few ms, whereas the surrounding GC base pairs in a dodecamer have lifetimes of about 100 ms. The (2AP)T base pair has a shorter lifetime than the corresponding AT base pair. The temperature dependent optical absorption, and for the 2AP containing oligonucleotide fluorescence, were used to study the single strand-duplex equilibrium of the decamers. The results indicate that NMR and the optical techniques, although applied at very different concentrations, monitor the same conformational transition of the oligonucleotide.

2-Aminopurine↗
PubMed1987

Fibrinogen and the early stages of polymerization to fibrin as studied by dynamic laser light scattering.

Human fibrinogen and the polymerization of fibrin after activation by the enzymes, thrombin and Batroxobin, were studied by means of dynamic laser light scattering (DLS). The apparent diffusion constant, D, for fibrinogen was measured and has a value of (1.80 +/- 0.42) X 10(-7) cm2 X s-1. D was found to contain contributions from the translational diffusion constant (Dt) as well as from the rotational diffusion constant (Dr). A comparison between experimental and calculated values of Dr and Dt suggests that fibrinogen in the absence of added Ca2+ expresses a certain degree of flexibility, while it is straightened in the presence of added Ca2+. The time dependence of D showed periodic oscillations, while the average D values decreased with time. Thrombin and Batroxobin caused similar behaviour of D. The period length was related to the enzyme concentration, clotting time (Ct) and the rate of release of fibrinopeptide A (FPA). No periodic oscillations were observed in experiments where the enzyme was replaced by saline, or in experiments using a dysfunctional fibrinogen (fibrinogen Aarhus) which displayed slow rates of FPA-release and polymerization. We propose that the periodic oscillations in a system far from equilibrium may be explained by conformational changes occurring in the fibrinogen molecule during enzyme activation and polymerization.

Batroxobin↗
PubMed1984

Structure-function relationships of human factor VIII complex studied by thioredoxin dependent disulfide reduction.

A highly purified, multimeric factor VIII complex composed of VIII: vWF and some factor VIII: C contained about 100 disulfides per subunit of Mr 260,000. Limited reduction of disulfide bonds in this complex by NADPH, thioredoxin reductase and thioredoxin leads to partial disaggregation of the multimeric VIII:vWF with concomitant loss of its platelet agglutinating activity in the presence of ristocetin, and with dissociation of factor VIII:C from the complex. During this event, no Mr 260,000 subunit of VIII:vWF is discernible. However, prolonged reduction results in the appearance of different multimers, and of some Mr 260,000 subunits. An N-terminal amino acid sequence for VIII:vWF was deduced. Two half-cystine residues in this sequence were shown to be involved in the reaction with thioredoxin. It appears possible that the thioredoxin system or other redox systems may play a role in regulation of factor VIII activities and of hemostatic processes in vivo.

Amino Acid Sequence↗
PubMed1984

Fibrin gels as biological filters and interfaces.

We present data which show that fibrin gels are ordered network structures, the porosity of which is determined by the amount of thrombin being present during the activation step preceding gelation. On activation of fibrinogen, fibrinopeptides are released and simultaneously polymers are formed, obeying apparent first order kinetics. The pore size of the network is inversely related to the rate of polymer formation. It is proposed that at the time of gelation the polymers form an ordered lattice structure, which in the organism may serve as a biological interface.

Chromatography, Gel↗