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Biomedical subjects

B Sjöberg

Publications and source records attributed to B Sjöberg.

At least 19 recordsLinked to original sources
PubMed2002

Adaptive stress response of glutathione and uric acid metabolism in man following controlled exercise and diet.

Ergometer cycling performance as well as acute exercise-induced changes in the metabolism of energy-intermediates and glutathione (GSH) were investigated in skeletal muscle (SM) of 15 healthy young male subjects (VO(2max) approximately 54.7 mL kg(-1) min(-1), age approximately 25 years), before and after 3 days of controlled 'ìoverload-training' in combination with either high (62% of energy intake) or low (26% of energy intake) dietary intake of carbohydrates. The intake of a carbohydrate-rich diet clearly reduced the depletion of SM glycogen following the short-term training period, paralleled with a positive effect on the endurance performance, but not on high-intensity work-performance. An 'delayed over-reaching effect', defined as impaired work-performance, was observed after 2.5 days of recovery from the short-term training period, irrespective of the carbohydrate content of the diet and basal glycogen level in SM. Taken together, the main and novel findings of present investigation are: (1) an acute decrease of reduced GSH content and altered thiol-redox homeostasis in SM induced by strenuous high-intensity exercise; (2) an adaptive elevation of basal GSH level following the short-term training period; (3) an adaptive decrease of basal GSH level following 2.5 days recovery from training; (4) evidence of a relationship between the SM fibre type, physical performance capacity and GSH turnover during acute bouts of exercise; and (5) no evident effect of the level of carbohydrate intake on metabolism of GSH or energy intermediates. Furthermore, the induction of acute oxidative stress in exercising human SM and the adaptive responses to training are suggested to provide a protective antioxidant phenotype to the exercising SM during periods with repeated intense intermittent training.

Adaptation, Physiological↗
PubMed2001

Clinical outcome or abdominal urethropexy-colposuspension: a long-term follow-up.

The aim of this study was to investigate the long-term results of abdominal urethropexy-colposuspension in terms of cure rate of stress urinary incontinence, complications and side effects. Between 1985 and 1992, 169 women between 27 and 79 years old underwent abdominal urethropexy-colposuspension at Stockholm Söder Hospital. In 1997 they were invited to participate in a long-term follow-up study, 5-11 years after the operation. One hundred and thirty-one women (78%) were willing to attend for a clinical review; 38 were lost to follow-up. At the follow-up visit all women were assessed with medical history, symptoms of incontinence, and their satisfaction and problems after the operation, following a predefined protocol. Peri- and postoperative data were retrieved from the files. The patients underwent a gynecological examination, measurement of residual urine volume and a provocative leakage test. One hundred and nine women (83%) were satisfied with the results of the operation and 22 (17%) were not. Seventy-one (54%) were subjectively completely dry, 48 (35%) had a little leakage and 14 (11%) had frequent leakage; 122 women were continent in the provocation test, and only 9 (7%) demonstrated leakage. The cure rate for stress incontinence was 93%. According to their medical histories 63 (48%) women had mixed incontinence before their operation. At the follow-up examination 43 of these 63 women still had symptoms of urgency. Twenty-six women with genuine stress incontinence before the operation had developed urgency or urge incontinence during the follow-up period. Urge symptoms before operation was a negative prognostic factor for a good outcome in terms of subjective cure of incontinence, but had no impact on objective cure rate or satisfaction of the operation. The cure rate for stress incontinence was high but still there were women who were not satisfied with the operation. Most of these complained of urge incontinence. There were few serious complications. The objective cure rate was better than the subjective cure rate.

Adult↗
PubMed2000

Methyl-RNA: an evolutionary bridge between RNA and DNA?

Given the apparent limitation of double-stranded RNA (dsRNA) genomes to about 30 kb, together with the complexity of DNA synthesis, it appears difficult for a dsRNA genome to encode all the information required before the transition from an RNA to a DNA genome. Ribonucleotide reductase itself, which synthesizes deoxyribonucleotides from ribonucleotides, requires complex protein radical chemistry, and RNA world genomes may have reached their limits of coding capacity well before such complex enzymes had evolved. The transition from RNA to DNA thus appears to require intermediate steps, and we suggest that the naturally occurring 2'-O-methylated RNA, with chemical properties intermediate between RNA and DNA, is a suitable candidate.

DNA↗
PubMed2000

A clinical study of root surface conditioning with an EDTA gel. I. Nonsurgical periodontal treatment.

The present study was undertaken to investigate if subgingival administration of an EDTA gel has any adjunctive effect to subgingival and supragingival root debridement. The investigation was performed in one study center involving 6 clinical investigators and 91 patients. The patients were selected from 2 patient populations: 41 were included from a consecutive referral material on a voluntary basis, and 50 were included from a maintenance care material at the clinic. No significant differences were found between the EDTA-treated and control groups with respect to clinical attachment gain or probing pocket depth reduction. The referral patients showed a significant improvement of pocket depth and attachment gain compared to maintenance care patients at the clinic. In multiple regression analyses, it was found that patients with small attachment losses at baseline responded better to treatment than patients with severe periodontitis. Also, in multivariate analyses, referral patients responded better than maintenance patients when controlling for other predictors.

Adult↗
PubMed1997

Structure and thermodynamics of nonideal solutions of colloidal particles: investigation of salt-free solutions of human serum albumin by using small-angle neutron scattering and Monte Carlo simulation.

The understanding of the structural and thermodynamic properties of moderately or highly concentrated solutions is fundamental, e.g., in medicine and biology and also in many technical processes. In this work, we have used the small-angle neutron scattering method (SANS), in combination with Monte Carlo simulation, to study salt-free solutions of human serum albumin (HSA) in the concentration range up to 0.26 g ml-1. The model calculations of the theoretical SANS intensities are quite general, thus avoiding the approximation that the relative positions and orientations of the particles are independent of each other. The computation of the theoretical intensities also includes the calculation of a "thermodynamic' intensity scattered at zero angle, which is obtained via the nonideal part of the chemical potential. The latter quantity is obtained by applying the test particle method during the Monte Carlo simulations. It is found that the SANS data can be explained by a model where the HSA molecules behave as hard ellipsoids of revolution with semiaxes a = 6.8 nm, b = c = 1.9 nm. In addition to the hard core interaction, the particles are also surrounded by a soft, repulsive rectangular-shaped potential which is spherically oriented around the particles. The combination of SANS and statistical thermodynamics also allows a determination of the nonideal part of the chemical potential and the activity coefficient of HSA. As expected the activity coefficient deviates strongly from the value one (several powers of ten) already at fairly low concentrations: the effects are comparable to, or even larger than, for instance hydrophobic or van der Waals interaction.

Chemical Phenomena↗
PubMed1997

Skeletal muscle of trained and untrained paraplegics and tetraplegics.

The effect of physical conditioning on skeletal muscle of individuals with spinal cord injuries (SCI) has been investigated. The anterior portion of the deltoid muscle (active in wheel-chair propulsion) of untrained and endurance-trained paraplegics and tetraplegics, as well as that of untrained able-bodied subjects, was studied. The characterization involved fibre type distribution, capillarization, fibre areas and also oxidative and glycolytic enzyme levels. A general trend towards a successively higher proportion of type I fibres and lower proportion of type IIB fibres was noted in the order of able-bodied subjects (type I, 42%; type IIB, 41%, n = 8), paraplegics (type I, 57%; type IIB, 13%, n = 13) and tetraplegics (type I, 74%; type IIB, 4.5%, n = 11). The trained SCI groups had significantly higher levels of the citric acid cycle marker enzyme citrate synthase (34% and 63%) than the untrained SCI groups and able-bodied subjects, respectively. The glycolytic marker enzyme 6-phosphofructokinase was 32% lower in the tetraplegic groups than in the other groups. In contrast, the fatty acid oxidation marker enzyme 3-hydroxyacyl-CoA dehydrogenase was markedly higher in the tetraplegic group than in the able-bodied subjects (58%) and tended to be higher (21%, P < 0.1) than in the paraplegic group. The trained SCI groups displayed significantly higher (28%) levels of capillaries per fibre than the untrained SCI groups, which had about the same levels as the untrained able-bodied subjects. It is concluded that several of the findings are in line with normal muscular adaptation, whereas others are unexpected and support a hypothesis that some of the findings might be due to differences between the groups in, for instance, hormone levels or in types of muscular load.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1997

Interactory effect between marginal plaque and subgingival proximal restorations on periodontal pocket depth.

The purpose of the present study was to investigate the influence of plaque on periodontal pocket depth adjacent to proximal amalgam restorations after non-surgical periodontal treatment. From 120 randomly selected patients 200 proximal premolar- or molar sites with subgingival restorations (test sites) and 200 contralateral unrestored sites within the same patient (control sites) were included if plaque was present on test as well as on control sites. At baseline the periodontal mean pocket depth adjacent to subgingival restorations were found to be significantly deeper (0.25 mm) than for control sites. After treatment, 24% of the initially subgingivally located restorations were registered as supragingival restorations. The differences according to mean pocket depth between supragingival restorations and corresponding control sites after treatment were found to be statistically non-significant. At reexamination mean pocket depth adjacent to proximal restorations with plaque were significantly deeper than their contralateral unrestored sites (mean difference 0.34 mm), while a non-significant difference was calculated for subgingival restorations without plaque. Subgingival restorations with their apical borders still located subgingivally after periodontal treatment should be regarded as a risk factor in periodontitis progression. Consequently, placement of the restoration margin supragingivally is recommended, especially in periodontitis-prone patients with an insufficient plaque control.

Adult↗
PubMed1994

Interparticle interactions and structure in nonideal solutions of human serum albumin studied by small-angle neutron scattering and Monte Carlo simulation.

Moderately or highly concentrated nonideal solutions of macromolecules are very important systems e.g. in biology and in many technical processes. In this work we have used the small-angle neutron scattering technique (SANS) to study the interactions and interparticle structure in solutions of human serum albumin (HSA) up to a concentration of 0.26 g/cm3 in 1.08 M NaCl. In order to obtain a model for the interactions we have combined the SANS data with results obtained by Monte Carlo simulations where we calculate the structure factor S(Q) and the pair correlation function g(r). The advantage of using the Monte Carlo method is that completely general models for the particle shape and the interactions can be considered. It is found that the SANS data can be explained by a model where the shape of the HSA molecule is approximated by an ellipsoid of revolution with semiaxes a = 6.8 nm and b = c = 1.9 nm. The interaction potential between the HSA molecules consists of two parts: (a) the molecules are hard and impenetrable and (b) the molecules are surrounded by a spherically symmetric repulsive potential which can be expressed by an empirical formula containing the HSA concentration and the centre-centre distances as the only variables.

Humans↗
PubMed1993

Prediction of valency and productivity: an empirical study of longterm group psychotherapy.

With reference to W. R. Bion's theory about individual's reactions to group stimuli the main hypothesis was formulated thus: individual's Valency (V) and Productivity (W) undergo changes in certain (definable) directions under the influence of longterm group psychotherapy. The main hypothesis was refined into seven sub-hypotheses. These were measured by four projective tests: Reaction Group Situation Test (RGST), Self Perceptual Q-sort (SPQ), Q-SORT(overt) and Q-SORT(covert). 48.0% of the total number of modalities, 120 out of 252, developed in a predicted and eligible direction. 29.0%, 74 modalities out of 252, remained unchanged whereas 23.0%, 58 modalities out of 252, developed in an opposite to predicted and non-eligible direction. Group members' Productivity (W) developed most of all the modalities in a predicted (eligible) direction. Group members' Valency and Productivity pattern (VP) changed least of all the modalities. The group members Valency (V) for the basic assumption Dependency (baD) developed most of all the modalities in an opposite to predicted, i.e. non-eligible direction.

Adaptation, Psychological↗
PubMed1992

Structure of RecA-DNA complexes studied by combination of linear dichroism and small-angle neutron scattering measurements on flow-oriented samples.

By combining anisotropy of small-angle neutron scattering (SANS) and optical anisotropy (linear dichroism, l.d.) on flow-oriented RecA-DNA complexes, the average DNA-base orientation has been determined in RecA complexes with double-stranded (ds) as well as single-stranded (ss) DNA. From the anisotropy of the two-dimensional SANS intensity representation, the second moment orientation function S is obtained. Knowledge of S is crucial for the interpretation of l.d. spectra in terms of orientation of the DNA bases and the aromatic amino acid residues. The DNA-base planes are essentially perpendicular to the fibre axis of the complex between RecA and dsDNA in the presence of cofactor ATP gamma S. A somewhat tilted base geometry is found for the RecA-ATP gamma S complexes with single-stranded poly(dT) and poly(d epsilon A). This behaviour contrasts the RecA-ssDNA complex formed without cofactor which displays a poor orientation of the bases. Well-ordered bases in the ssDNA-RecA complex is possibly reflecting the role of RecA in preparing a nucleotide strand for base-pairing in the search-for-homology process. While the central SANS intensity is essentially independent of the pitch of the helical complex, a secondary intensity maximum, which becomes focused upon flow orientation, is found to be a sensitive measure of the pitch. The pitch values for the complexes compare well with cryo-electron microscopy results but are slightly larger than those seen for uranyl-stained samples.

Adenosine Triphosphate↗
PubMed1992

Temperature dependence of the kinetics of the urea-induced dissociation of human plasma alpha 2-macroglobulin into half-molecules. A minimum rate at 15 degrees C indicates hydrophobic interaction between the subunits.

The kinetics of the urea-induced dissociation of human plasma alpha 2-macroglobulin to half-molecules has been studied as a function of temperature by using small-angle scattering of X-rays and neutrons. The most striking result of the present investigation is that there is a minimum in reaction rate at about 15 degrees C, and that the rate increases when the temperature is lowered, or raised, from that value. By analyzing the first-order rate constants in terms of transition-state theory it was found that the dissociation is associated with a large and positive change in heat capacity between the activated complex and native alpha 2-macroglobulin (delta CP is in the range 5 to 6 kJ mol-1 K-1). In analogy with pure thermodynamic investigations, where a large change in heat capacity normally is interpreted as a melting of hydrophobic interaction, we therefore propose that hydrophobic interaction is involved in the so-called non-covalent interactions between the subunits of alpha 2-macroglobulin. As a result of the present investigation, it also follows that the free energy of activation delta G has a maximum at about 32 degrees C, whereas the enthalpy of activation delta H and the entropy of activation delta S are zero at about 15 degrees C and 32 degrees C, respectively. These temperatures are slightly dependent upon the concentration of urea and upon whether the reaction is run in a 1H or a 2H medium. Furthermore, from the kinetic point of view, at low temperature the reaction can be characterized as enthalpy driven, whereas at high temperature, it can be characterized as entropy driven.

Humans↗
PubMed1991

Kinetics of the urea-induced dissociation of human plasma alpha 2-macroglobulin as measured by small-angle neutron scattering.

The kinetics of the urea-induced dissociation of human plasma alpha 2-macroglobulin into two half-molecular fragments was investigated at 21.0 degrees C by using small-angle neutron scattering. The relative change in molecular mass that occurs upon dissociation was monitored by recording the forward scattering of neutrons as a function of time. All these kinetic data can be explained by a reaction that is first-order with respect to the concentration of undissociated alpha 2-macroglobulin. The velocity constant is a function of urea concentration and it varies within wide limits. For instance, the half-life of the reaction at the lowest concentration of [2H]urea studied (2.70 M) is 328 h, whereas the same value at the highest concentration of [2H]urea (6.24 M) is only 8 min. Measurements were made both with [1H]urea in 1H2O and with [2H]urea in 99% 2H2O, and it was found that there is a pronounced kinetic isotope effect, i.e. the dissociation is 4 times faster in the 1H-containing medium as compared with the 2H-containing medium at the same molar concentration of urea. From the angular dependence of the neutron scattering it can be concluded that the dissociation is associated with a drastic change in structure. This is directly shown by the radius of gyration, which increases from about 7.4 nm immediately after the addition of urea up to about 9.4 nm when the protein is fully dissociated. A structural analysis shows that the scattering curve of urea-dissociated alpha 2-macroglobulin can best be explained by that of a Gaussian coil with a radius of gyration equal to 9.44 nm. These data indicate that the so-called non-covalent interaction of alpha 2-macroglobulin probably is more complicated than just a pure hydrophobic interaction. Finally, it is also shown that the dissociation is accompanied by a loss in trypsin-binding activity, which is directly related to the fraction of dissociated protein.

Animals↗
PubMed1990

Structure of a RecA-DNA complex from linear dichroism and small-angle neutron-scattering in flow-oriented solution.

Small-angle neutron-scattering (SANS) and ultraviolet linear dichroism (l.d.) were measured on identical samples of a RecA-double-stranded (ds) DNA complex, including cofactor adenosine 5'-O-thiotriphosphate, which were aligned by flow in two equivalent Couette devices made of niobium and silica, transparent to neutrons and to ultraviolet light, respectively. The SANS anisotropy indicates a modest orientation of the RecA-dsDNA fiber with the helix axis parallel to the flow field. By correlation with the corresponding l.d. of the DNA at the same orientation conditions, it is inferred that the DNA bases have a local orientation that is approximately perpendicular to the helix axis. By comparison with the worse orientation in single-stranded DNA-RecA, this conclusion suggests that the dsDNA in its complex with RecA is not strand separated, and may be accommodated as an essentially unperturbed, straight double helix running along the RecA polymer fiber. The SANS anisotropy is also found to support the assignment of a subsidiary intensity maximum as originating from the pitch of a helical fiber.

Animals↗
PubMed1990

The H(+)-induced dissociation of human plasma alpha 2-macroglobulin. An investigation using small-angle neutron scattering and test of trypsin binding activity.

The dissociation of the tetrameric alpha 2-macroglobulin molecule into two half-molecular fragments, which occurs at pH less than 4.5, has been investigated using the small-angle neutron scattering method, and test of trypsin binding activity. Best fit with the relative forward scattering of neutrons is obtained for a model where the dissociation of the protein is driven by the uptake of H+ on altogether four acid-base groups, one per monomeric subunit of alpha 2-macroglobulin. These groups are not (or only slightly) accessible in the native tetramer, but become exposed to the solvent after dissociation of the protein. The H(+)-binding constant obtained for these groups, after dissociation of the protein, log K1 in the range 4.2-4.5, suggests that they are most probably carboxylate groups. From the about 10% increase in the radius of gyration, which occurs when lowering the pH from 4.5 to 2.0, we can conclude that the dissociation is associated with a change in structure of the protein. Tests of trypsin binding show that there is also an irreversible loss in trypsin binding activity, which is directly related to the fraction of dissociated protein. Thus, at pH less than 4.5, there is a transition of alpha 2-macroglobulin which results simultaneously in dissociation, disorganisation of the conformation of the subunits and loss in activity.

Binding Sites↗
PubMed1990

Effect of combined treatment with phenylpropanolamine and estriol, compared with estriol treatment alone, in postmenopausal women with stress urinary incontinence.

Twenty-nine postmenopausal women with slight to severe stress urinary incontinence and estrogen deficiency symptoms in the urogenital tract were treated with estriol, p.o. 4 mg once daily, and either phenylpropanolamine (PPA), p.o. 50 mg twice daily, or placebo for periods of 6 weeks according to a randomized double-blind crossover schedule. At urodynamic recordings the maximum urethral closure pressure increased by 22% with combined treatment (p less than 0.001) and an additional effect of PPA to estriol was shown (p = 0.022). The pressure transmission ratio increased, by about 15%, with both treatments (p less than 0.07). The number of leakage episodes was reduced by 28% with combined treatment (p = 0.007), but not with estriol alone (p = 0.08). Both combined treatment and estriol alone reduced significantly (p less than 0.01) the urinary incontinence complaints. Twelve women (43%) preferred combined treatment, while 7 (25%) preferred estriol alone. In women with initially slight to very severe urine loss, combined treatment reduced also (p = 0.02) the amount of urine loss, measured at a standardized physical stress test. Signs of estrogen deficiency in vulva, vagina and urethra were reduced, 75% (p less than 0.001) or 65% (p = 0.001) with estriol given in combination with PPA or alone. Maturation index of both urethral and vaginal epithelium displayed significant changes. It is concluded that the combined treatment, PPA + estriol, by affecting both the muscular and mucosal factor of the urethra, is more effective than estriol alone for treatment of female stress urinary incontinence in the postmenopausal ages.

Double-Blind Method↗
PubMed1989

Molecular organization of human plasma alpha 2-macroglobulin and its trypsin complexes. A small-angle x-ray scattering investigation.

The molecular organization of human plasma alpha 2-macroglobulin (alpha 2M), and its 1:1 and 1:2 trypsin complexes, have been investigated using the small-angle x-ray scattering method. All the experimental data can be explained by the same basic model, consisting of three oblate-shaped domains arranged in a sandwich-like structure. Each of the larger peripheral domains consists of two parallel elliptic cylinders associated side-by-side, whereas the smaller central domain consists of just one elliptic cylinder. In the native molecule the three domains are separated by regions of low protein density. Upon trypsin binding the dimensions of the four peripheral cylinders remain unchanged, but their positioning in space is reorganized so that the whole molecule becomes more compact. The model thus offers a plausible explanation for the mechanism of inactivating of the protease by entrapping it between the two larger domains. By comparing the shape and dimensions of the total molecule with those determined for the half-molecular fragment, obtained after reducing the intersubunit disulfide bonds, we propose that the fragment consists of just one of the peripheral domains plus half of the central domain. Different projections of the model are consistent with the electron micrographs of alpha 2M given in the literature. The model can also explain many of the physical and chemical properties recorded for alpha 2M and its protease complexes.

Disulfides↗