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Biomedical subjects

S Johansson

Publications and source records attributed to S Johansson.

At least 19 recordsLinked to original sources
PubMed1995

Chondrocyte and chondrosarcoma cell integrins with affinity for collagen type II and their response to mechanical stress.

Mechanical stress is an important regulator of chondrocyte functions but the mechanisms by which chondrocytes sense mechanical signals are unknown. Receptors for matrix molecules are likely involved in the mechanical signaling. In the first part of this study we identified integrins with affinity for the cartilage-specific collagen type II. We report that the collagen-binding integrins alpha 1 beta 1 and alpha 2 beta 1 isolated from bovine chondrocytes or human chondrosarcoma cells bound collagen type II as judged from affinity chromatography. The integrins alpha 3 beta 1 or alpha 9 beta 1 did not bind collagen type II-Sepharose. In the second part of the study we investigated the effect of mechanical stress on expression of matrix molecules and integrin subunits. Chondrocytes and chondrosarcoma cells, cultured on uncoated flexible silicone membranes in the presence of serum, were exposed to mechanical stress by the Flexercell system. Dynamic stimulation of chondrocytes for 3 h increased the mRNA expression of collagen type II and aggrecan as judged by Northern blotting, while the beta 1-integrin subunit was not changed. When chondrosarcoma cells were exposed to mechanical stimulation under the same conditions, mRNA expression of alpha 5 was found to increase while beta 1, alpha 2, and alpha v did not increase to significant levels. In another study the effect of mechanical stress on integrins was investigated when the cells were cultured on collagen type II-coated flex-dishes. Three hours of dynamic stress increased the mRNA expression of alpha 2-integrin subunit while the level of mRNA for integrin subunits beta 1, alpha 1, alpha 5, and alpha v showed no or small changes, indicating that matrix components may modulate the expression of integrins during mechanical stress.

Aggrecans↗
PubMed1995

Lack of beta 1 integrin gene in embryonic stem cells affects morphology, adhesion, and migration but not integration into the inner cell mass of blastocysts.

A gene trap-type targeting vector was designed to inactivate the beta 1 integrin gene in embryonic stem (ES) cells. Using this vector more than 50% of the ES cell clones acquired a disruption in the beta 1 integrin gene and a single clone was mutated in both alleles. The homozygous mutant did not produce beta 1 integrin mRNA or protein, while alpha 3, alpha 5, and alpha 6 integrin subunits were transcribed but not detectable on the cell surface. Heterozygous mutants showed reduced beta 1 expression and surface localization of alpha/beta 1 heterodimers. The alpha V subunit expression was not impaired on any of the mutants. Homozygous ES cell mutants lacked adhesiveness for laminin and fibronectin but not for vitronectin and showed a reduced association with a fibroblast feeder layer. Furthermore, they did not migrate towards chemoattractants in fibroblast medium. None of these functions were impaired in heterozygous mutants. Scanning electron microscopy revealed that homozygous cells showed fewer cell-cell junctions and had many microvilli not usually found on wild type and heterozygous cells. This profound change in cell shape is not associated with gross alterations in the expression and distribution of cytoskeletal components. Unexpectedly, microinjection into blastocysts demonstrated full integration of homozygous and heterozygous mutants into the inner cell mass. This will allow studies of the consequences of beta 1 integrin deficiency in several in vivo situations.

Animals↗
PubMed1995

Release of cytokines, polymorphonuclear elastase and terminal C5b-9 complement complex by infusion of wound drainage blood.

25 patients undergoing total hip replacement surgery were studied in an investigation of release of cytokines (interleukin-1 beta, IL-1 beta; interleukin-6, IL-6; interleukin-8, IL-8; and tumor necrosis factor-alpha, TNF-alpha), PMN elastase and terminal C5b-9 complement complexes (TCC) at the time of collection and transfusion of autologous blood. 15 patients received wound blood that was washed and centrifuged before being transfused as an erythrocyte suspension. In this blood there were no elevations in the concentrations of cytokines, TNF-alpha, PMN elastase or TCC, and there was no increase in these variables in plasma after transfusion of wound blood. 10 patients received postoperatively-collected drainage blood. There were high amounts of cytokines, PMN elastase and TCC in this blood, and filtration of the collected drainage blood did not reduce the concentrations of these factors, except those of TCC. When the collected drainage blood was infused, elevated plasma concentrations of IL-6, IL-8 and PMN elastase were observed 1 and 60 minutes after completing the transfusion. No differences regarding blood pressure, oxygen saturation (SpO2), and hemoglobin concentration between the groups were recorded.

Aged↗
PubMed1994

Single-channel currents trigger action potentials in small cultured hippocampal neurons.

Spontaneous neuronal impulse activity appears to play a key role in some neural processes, such as the normal establishment of interneuronal connections during development. In addition, spontaneous impulses may be essential for the functional operation of neuronal networks. Mechanisms of spontaneous non-pacemaker impulse generation are, however, not well known. In this work, spontaneous electrical activity in small cultured hippocampal neurons from rat was studied with tight-seal recording techniques. The results demonstrate that spontaneous individual openings of single ion channels can trigger impulse generation in these high-resistance cells. First, impulses recorded in the whole-cell mode were apparently induced by spontaneous plateau-potential events showing the characteristics expected from individual openings and closures of ion channels. Second, patch-clamp recordings in the cell-attached configuration showed that openings of single ion channels in the patch membrane could trigger cellular impulses, detected as biphasic current deflections. These findings suggest that the random gating of ion channel molecules can be used as a mechanism for stochastic triggering of spontaneous impulses in mammalian central neurons.

Action Potentials↗
PubMed1994

Purification and characterization of integrin alpha 9 beta 1.

A new beta 1-containing integrin was isolated from rat liver by affinity chromatography on Sepharose conjugated with the peptide GRGDSPC. The interaction was weakened but not abolished when the arginine and/or aspartic acid in the peptide were replaced with lysine and glutamic acid, respectively. In contrast, the cysteine was necessary for binding of the integrin. The beta 1-associated protein, referred to as alpha 9, had an N-terminal amino acid sequence related to but distinct from previously described integrin alpha-subunits. In addition, an internal peptide sequence was obtained which confirmed that the protein is a new member of the family of integrin alpha-subunits. An antiserum raised against a synthetic peptide corresponding to amino acids 1-16 of alpha 9 reacted specifically with this protein and was used to identify alpha 9 in several tissues. The integrin alpha 9 beta 1 was not retained on Sepharose conjugated with Englebreth-Holm-Swarm tumor (EHS)-laminin, collagen type I, or a 105-kDa cell-binding fragment of fibronectin. However, it did bind specifically to EHS-laminin and collagen type I adsorbed to plastic microtiter wells. The sites of the interactions were localized to fragment E8 of EHS-laminin and to cyanogen bromide fragment 8 of collagen alpha 1(I) and were not inhibited by soluble RGD-containing peptides. The results indicate that alpha 9 beta 1 is a widely distributed laminin/collagen receptor which may have additional, yet unidentified ligands.

Amino Acid Sequence↗
PubMed1994

Laminin isoforms promote attachment of hepatocytes via different integrins.

Three isoforms of laminin were compared for the ability to promote adhesion of primary rat hepatocytes. In tests of initial attachment to these substrates, kidney laminin (alpha k, beta 1, gamma 1, and alpha k, beta 2, gamma 1) was shown to be a more efficient substrate than Engelbreth Holm Swarm (EHS) (alpha 1, beta 1, gamma 1) or heart laminin (alpha 2, beta 1, gamma 1, and alpha 2, beta 2, gamma 1). Hepatocyte attachment to EHS laminin and heart laminin was completely inhibited by antibodies specific for the integrin subunit beta 1, while a combination of beta 1 integrin antibodies and GRGDS peptide was needed for total inhibition of hepatocyte attachment to kidney laminin. Antiserum directed to the integrin subunit beta 3 could not substitute for the GRGDS peptide in this inhibition. Antibodies against the integrin subunit alpha 1 efficiently blocked adhesion of hepatocytes to collagen type I and to the P1 domain of EHS laminin. However, this antibody had essentially no effect on the attachment to kidney laminin and had only a minor inhibitory effect on attachment to heart laminin, to intact EHS laminin, or to the isolated fragment E8 of EHS laminin. Combining the alpha 1 integrin antibody with GRGDS peptide gave no further inhibition on these substrates. These results show that a recently described isoform of laminin from bovine kidney is an efficient substrate for initial attachment of hepatocytes, interacting with at least one beta 1-containing integrin and an RGD-dependent integrin not containing beta 1 or beta 3 subunits. Native EHS laminin uses integrin alpha 1 beta 1 for hepatocyte binding to the center of the cross (fragment P1) and other beta 1 integrin(s) in addition to alpha 1 beta 1 as receptors for the distal part of the long arm (fragment E8).

Animals↗
PubMed1994

Changes in the pattern of expression of alkaline phosphatase in the mouse uterus and placenta during gestation.

The development of the rodent chorio-allantoic placenta is a complicated process that results in the formation of a transport system capable of sustaining embryonic and fetal growth and development. Intimately linked to this process is alkaline phosphatase (AP), a cell-surface glycoprotein that possibly functions as a transport protein. In the present study, we have mapped the location of AP-expressing cells in the mouse utero-placental unit during the development of the chorio-allantoic placenta by use of enzyme histochemistry and in situ hybridization histochemistry. We found that at implantation the expression of the tissue non-specific AP (TNAP) gene is located exclusively in the decidua and that most of this decidual expression ceases as the placenta starts to form. One exception is a mesometrially located marginal zone of the decidua, which continues to express the TNAP gene until day 12 and the active protein until at least day 16. Trophoblasts of the chorion already express AP before the time of fusion with the ectoplacental cone, after which AP is expressed by trophoblasts of the resulting ectoplacental plate. AP expression in the mature chorio-allantoic placenta is localized in the placental labyrinth and spongy zones. In the latter zone, expression ceases on about day 14. Giant trophoblasts start to express AP on about day 10, with some cells still positive for AP at day 16. The yolk sac does not express AP at any developmental stage. The results show that AP expression during placental development is neither restricted to cells known to be involved in transport, nor expressed in all cells thought to be involved in this transport. This may indicate that AP is not merely a transport protein but has additional functions.

Alkaline Phosphatase↗
PubMed1994

Association between fibrinogen and other risk factors for cardiovascular disease in men and women. Results from the Göteborg MONICA survey 1985.

Plasma fibrinogen and its association to other risk factors for cardiovascular disease was investigated in a random sample of 691 men and 739 women, aged 25 to 64 years, participating in the Göteborg MONICA survey. In both genders univariate analyses revealed significantly positive correlations between plasma fibrinogen and age, body mass index (BMI), waist/hip ratio (WHR), systolic blood pressure, serum cholesterol and triglycerides and a negative correlation to high-density lipoprotein (HDL) cholesterol; however, the degree of relationship varied between men and women. Smoking was significantly correlated to fibrinogen (P < 0.001) in men, whereas the association was weaker in women. Multivariate analysis showed that plasma fibrinogen in both genders was significantly correlated to age, smoking, and BMI. The influence of smoking was stronger in men and BMI was stronger in women. Furthermore, the association of fibrinogen to HDL cholesterol was significant only in men and to triglycerides only in women. Plasma fibrinogen was significantly related to gender; when all other significant variables were taken into account, women had higher fibrinogen levels than men.

Adult↗
PubMed1994

Increase in mast cells and hyaluronic acid correlates to radiation-induced damage and loss of serous acinar cells in salivary glands: the parotid and submandibular glands differ in radiation sensitivity.

The detailed mechanisms which can explain the inherent radiosensitivity of salivary glands remain to be elucidated. Although DNA is the most plausible critical target for the lethal effects of irradiation, interactions with other constituents, such as cell membrane and neuropeptides, have been suggested to cause important physiological changes. Moreover, mast cells seem to be closely linked to radiation-induced pneumonitis. Therefore, in the present study the effects of fractionated irradiation on salivary glands have been assessed with special regard to the appearance of mast cells and its correlation with damage to gland parenchyma. Sprague-Dawley strain rats were unilaterally irradiated to the head and neck with the salivary glands within the radiation field. The irradiation was delivered once daily for 5 days to a total dose of 20, 35 and 45 Gy. The contralateral parotid and submandibular glands served as intra-animal controls and parallel analysis of glands was performed 2, 4, 10 or 180 days following the last radiation treatment. Morphological analysis revealed no obvious changes up to 10 days after the irradiation. At 180 days a radiation dose-dependent loss of gland parenchyma was seen, especially with regard to serious acinar cells in parotid gland and acinar cells and serous CGT (convoluted granular tubule) cells in the submandibular gland. These changes displayed a close correlation with a concomitant dose-dependent enhanced density of mast cells and staining for hyaluronic acid. This cell population seems to conform with the features of the connective tissue mast cell type. The parotid seems to be more sensitive to irradiation than the submandibular gland. Thus, the present results further strengthen the role of and the potential interaction of mast cells with radiation-induced tissue injury and alterations in normal tissue integrity.

Animals↗
PubMed1994

Identification of allergen components of the opportunistic yeast Pityrosporum orbiculare by monoclonal antibodies.

The yeast Pityrosporum orbiculare (P. orbiculare) is a member of the normal human cutaneous flora, but it is also associated with several clinical manifestations of the skin. We have previously observed IgE-binding components in P. orbiculare extracts, using sera from patients with atopic dermatitis. In the present study, we raised several monoclonal antibodies (MoAbs) against P. orbiculare to characterize some of its antigens, and used Candida albicans (C. albicans) as a control. We obtained several IgG1 MoAbs which specifically recognized P. orbiculare in ELISA. Two of these were selected for immunoblotting studies on P. orbiculare, and two patterns of reactivity emerged. Firstly, one MoAb showed a distinct band at a molecular mass of 67 kDa. In the second pattern, a sharp band at about 37 kDa appeared. In contrast, the IgM antibodies raised reacted with a 14-kDa component; but they reacted with C. albicans in addition to P. orbiculare. The IgG1 antibodies seemed to react with proteins, as their ability to react in ELISA with extract pretreated with protease was greatly reduced. In contrast, IgM MoAbs were much less affected, suggesting that they recognized nonprotein components. To determine whether these MoAbs-binding components were also recognized by human IgE, we adopted a radioimmunoassay (RIA) using the MoAbs as catcher antibodies. Both the 67-kDa and the 37-kDa components were IgE-binding proteins. P. orbiculare RAST positive sera were scored as positive in the RIA, whereas the control serum was not.

Allergens↗
PubMed1994

Graded action potentials generated by differentiated human neuroblastoma cells.

Stimulus-dependent impulses and resting membrane parameters of human SH-SY5Y neuroblastoma cells, induced to differentiate by retinoic acid, were investigated with tight-seal recording techniques. Mean resting potential was -53 mV, mean input resistance 2.1 G omega, mean capacitance 14 pF, and mean time constant 30 ms. Rectangular current steps induced clearly stimulus-dependent impulses, with stronger current steps causing impulses of larger amplitude. The degree of impulse variability differed significantly among different cells. The current thresholds for impulse generation ranged from 35 to 100 pA for 10 ms current steps. With longer current steps, thresholds below 10 pA were recorded. In response to 0.5-1 s long current steps, most cells generated only a single impulse, but a few cells generated two impulses. When two impulses were generated, the interval between the impulses decreased with increasing stimulus strength. Whole-cell currents were recorded under voltage-clamp conditions. Voltage-activated, tetrodotoxin-sensitive Na+ currents and 'delayed rectifier' K+ currents were recorded. The degree of impulse variability was correlated to the maximum Na+ current density. Cells with large Na+ currents showed little impulse variability, while a marked variability was recorded in cells with intermediate or small Na+ currents. Cells which generated more than one impulse in response to prolonged stimuli belonged to the group with large Na+ currents. Spontaneous impulse-currents were recorded from cell-attached membrane patches on intact cells. Also these impulses showed a large variability in amplitude: In each of five cells analysed, the peak-to-peak amplitude varied by a factor larger than 1.7.

Action Potentials↗
PubMed1994

Hemostatic and metabolic variables in women with polycystic ovary syndrome.

OBJECTIVE: To study whether a previously demonstrated increased morbidity in cardiovascular disease (CVD) and diabetes mellitus in women with polycystic ovary syndrome (PCOS) is associated with certain hemostatic variables that are known to be markers for CVD. DESIGN: The study was a trans-sectional follow-up study from a cohort of women with PCOS. SETTING: The women with PCOS were recruited from hospital clinics and referents were randomized from a population study of women from the same area. PARTICIPANTS: The investigation involved 28 women aged 43 to 62 years diagnosed to have PCOS on ovarian histopathology at wedge resection 25 to 34 years previously and 56 referents who were matched by age and body mass index. MAIN OUTCOME MEASURES: In connection with a clinical investigation, the hemostatic variables fibrinogen, von Willebrand factor antigen, factor VII procoagulant activity, factor VII antigen, and plasminogen activator inhibitor as well as the metabolic variables serum insulin and serum triglycerides were assayed. RESULTS: There was a strong positive correlation between serum concentrations of triglyceride, basal insulin, and abdominal obesity on the one hand, and plasminogen activator inhibitor, fibrinogen, and von Willebrand factor on the other, among women with PCOS as well as among referents. There were significantly higher mean concentrations of fibrinogen and factor VII:Ag among referents, but the mean values of most hemostatic variables studied showed no differences between the groups. CONCLUSION: Women with an altered metabolic profile were also found to have affected hemostatic factors, but PCOS in itself did not seem to influence them.

Adult↗
PubMed1993

Large-scale production of Vibrio cholerae toxin B subunit for use in oral vaccines.

By systematically manipulating promoter and ribosome binding structures, plasmid copy number and the structure of the cholera toxin B (CTB) subunit gene, we were able to develop a plasmid expression system that, when used in conjunction with an optimized growth medium, provided yields of CTB approaching one gram per liter. The CTB protein which was secreted to > 95%, could readily be purified from the growth medium of a V. cholerae production strain and was shown to be immunologically indistinguishable from previously used vaccine preparations of native or recombinant CTB.

Amino Acid Sequence↗
PubMed1993

Subjective symptoms and well-being differ in women and men after myocardial infarction.

The frequency of subjective cardiac and psychological complaints among men and women a year after a confirmed diagnosis of myocardial infarction (MI) were compared. Among 660 survivors, 595 patients completed mailed questionnaires at home one year after the MI. There were 421 men, mean age 67.1 +/- 10.7 years, and 174 women, mean age 72.1 +/- 10.6 years. Controlling for the significantly higher mean age among the women, the latter more often had a previous history of angina pectoris, 54.6% (P < or = 0.05) versus 42.9%, and heart failure, 24.7% versus 13.5% (P < or = 0.01). Despite these facts, the women were significantly less often referred to CCU, 82.2% versus 91.7% (P < or = 0.05). One year after the MI, controlling for differences in age and co-morbidity, women reported significantly higher frequencies of psychological and psychosomatic complaints, including sleep disturbances. These differences may have clinical implications for diagnosis and treatment of women with coronary heart disease.

Adult↗
PubMed1993

Urinary fibronectin in diagnosis and follow-up of patients with urinary bladder cancer.

The levels of fibronectin in urine from 106 patients with urinary bladder cancer, from 13 patients with benign urological disease and from 24 healthy control individuals were determined by an enzyme-linked immunosorbent assay (ELISA). The fibronectin levels in urine from patients with bladder cancer were higher than in patients with benign urothelial disease and in healthy controls. In 9 patients with bladder cancer, sampling was done both pre- and post-operatively. In these cases the fibronectin levels after operation were significantly lower than they had been before. Among 14 patients treated with BCG intravesically for superficial bladder tumours, those with complete remission of disease had less urinary fibronectin than those who did not respond to treatment. The data suggest that urinary fibronectin may be a useful marker for detecting urinary bladder cancer and for selecting patients for BCG treatment.

Albuminuria↗
PubMed1993

Practical aspects of 3,4-diaminopyridine treatment of the Lambert-Eaton myasthenic syndrome.

3,4-Diaminopyridine (3,4-DAP) given alone or combined with pyridostigmine is the recommended basic therapy in the Lambert-Eaton myasthenic syndrome (LEMS). We present and exemplify our routine test protocol for monitoring drug introduction and treatment regimen of cholinergic drugs in LEMS. The individual drug responses vary and no recommended standard doses exist. Routine electrophysiological repetitive nerve stimulation studies recording amplitude of initial compound muscle action potential (CMAP) in thenar muscles correlate excellently with clinical myasthenic muscle power tests in clinically affected muscle groups. Therefore repetitive clinical muscle power tests, that often are complicated by painful myalgia and activation potentiation, can be replaced by recordings of CMAP in the introduction and clinical follow up of cholinergic drug treatment in LEMS. Also, adverse effects and other treatment problems from the experience of continuous treatment of 19 LEMS patients with 3,4-DAP for up to 10 years are presented.

4-Aminopyridine↗