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S Johansson

Publications and source records attributed to S Johansson.

At least 19 recordsLinked to original sources
PubMed1992

Single K(+)-channel currents under steady-state potential conditions in small hippocampal neurons.

Small cultured hippocampal neurons from rat embryos were studied with the patch-clamp technique. Single-channel currents from outside-out membrane patches were recorded under steady-state potential conditions. The most frequently found channel types were selective to K+ and showed conductances of about 30 and 80 pS in the range -20 to 0 mV. Two basic kinetic patterns were observed for the 80 pS channels. In one type, the fraction of time spent in open state increased with potential, and in the other type it decreased. For both types of 80 pS channel, the distribution of dwell times in the open state was well described by the sum of two exponentials while three exponentials sometimes were required for dwell times in the closed state. The time constants of the fitted exponentials could vary considerably during an experiment.

Animals↗
PubMed1992

Disulfide arrangement of human insulin-like growth factor I derived from yeast and plasma.

The disulfide arrangement of yeast derived human insulin-like growth factor I (yIGF-I) was determined using a combination of Staphylococcus aureus V8 protease mapping, fast-atom-bombardment mass spectrometry as well as amino acid sequence and composition analysis. Three disulfide bridges were found between the following cysteine residues: Cys6-Cys48, Cys47-Cys52 and Cys18-Cys61. IGF-I isolated from human plasma (pIGF-I) was found to have an identical disulfide configuration. A yeast-derived isomeric form of IGF-I (yisoIGF-I) exhibited an altered disulfide arrangement: Cys6-Cys47, Cys48-Cys52 and Cys18-Cys61. Radioreceptor analysis of pIGF-I and yIGF-I showed high specific activity, 20,000 U/mg. However, yisoIGF-I demonstrated a severely reduced ability to bind to the IGF-I receptor (19%) and was less potent in provoking a mitogenic response in Balb/C 3T3 fibroblasts (50% at doses 10-100 ng/ml). The data demonstrate the importance of correct disulfide arrangement in IGF-I for full biological activity.

Amino Acid Sequence↗
PubMed1992

Separation of fibronectin from a plasma gelatinase using immobilized metal affinity chromatography.

Conventional preparations of plasma fibronectin are known to contain a co-purifying gelatinase [1986, J. Biol. Chem. 261, 4363-4366], but so far useful methods to remove the protease have not been available. In this study a number of different methods were tested in order to achieve separation of the two proteins. Immobilized metal affinity chromatography was found to be efficient for this purpose, and a convenient procedure to separate the two proteins under nondenaturing conditions on chelating Sepharose charged with Co2+, Ni2+, or Zn2+ is described. An alternative method employing pH gradient elution of an Fe3+ gel also resolved fibronectin from the gelatinase. The Fe3+ gel bound both proteins at pH 6.0 but not at pH 7.4, suggesting that the two proteins were phosphorylated. The described procedures will now allow studies of the functions of fibronectin in the absence of the contaminating protease.

Chromatography, Affinity↗
PubMed1992

Impulses of variable amplitude recorded from cell-attached patches on small hippocampal neurons.

Small cultured neurons from embryonic rat hippocampus were investigated with the cell-attached configuration of the patch-clamp technique. The currents associated with spontaneous cellular impulse generation were studied. The positive peak current amplitudes varied by a factor larger than 2.5 for 11 of 12 cells quantitatively investigated, suggesting underlying action potentials of variable amplitude. A simple RC-network was found to describe the properties of the patch membrane, and was used to calculate the underlying potential time course. The action potentials computed showed a considerable variation in amplitude. The results suggest that the impulse variability previously analysed with the whole-cell technique was not caused by dialysis of the cell interior.

Action Potentials↗
PubMed1992

cDNA cloning and sequencing of rat alpha 1-macroglobulin.

cDNA clones coding for the plasma protease inhibitor alpha 1-macroglobulin were isolated from a rat liver library. The obtained cDNA sequence contained 4701 nucleotides and had an open reading frame coding for a 1,500 amino acid long protein, including a 24 amino acid signal peptide. The identity of the deduced protein sequence as alpha 1-macroglobulin was established by comparison with published peptide sequences of the protein. The mature protein shares 53% and 57% overall amino acid identity with the two other identified members of the rat alpha-macroglobulin family, alpha 1-inhibitor 3 and alpha 2-macroglobulin. A sequence typical for an internal thiol ester was identified. Of the 24 cysteines, 23 are conserved with alpha 2-macroglobulin. However, instead of the two most C-terminal cysteines in alpha 2-macroglobulin, which forms a disulfide bridge in the receptor binding domain, alpha 1-macroglobulin contains phenylalanine. One mRNA species hybridizing with the alpha 1-macroglobulin probe was observed in rat and mouse liver RNA (approximately 6.2 kb), whereas no corresponding transcript was detected in RNA from human liver.

Amino Acid Sequence↗
PubMed1992

Laminin and its neurite outgrowth-promoting domain in the brain in Alzheimer's disease and Down's syndrome patients.

Immunocytochemistry, radioimmunoassay, immunoblotting, Northern analysis, and polymerase chain reaction (PCR) technique were applied to investigate the distribution of laminin and its neurite outgrowth domain in brains of neuropathologically verified cases of Alzheimer's disease and Down's syndrome. New antibodies against a neurite outgrowth domain of laminin were characterized and were used in localization of this peptide antigen in the human brain. Laminin was found as large punctate deposits in all plaques in the affected brains. Laminin synthesis was increased as assessed by RNA blotting and immunoblotting, and glial cells were heavily immunoreactive with antibodies for a neurite outgrowth-promoting peptide antigen of the B2 chain of laminin. This peptide antigen not only was produced by glial cells but also was deposited in the brain tissue. As this peptide antigen promotes neurite outgrowth at low concentrations, and is specifically neurotoxic at high concentrations, it may play a synergistic role with other molecules in inducing the sprouting and neurodegeneration occurring in brains of patients with either Alzheimer's disease or Down's syndrome.

Adult↗
PubMed1992

Control of cisplatin induced emesis--a multidisciplinary intervention strategy.

A pharmacological, behavioural and nursing intervention strategy was evaluated for prevention of cisplatin (50 mg m-2) induced emesis in ovarian cancer patients. 46 patients received metoclopramide 2.5 mg kg-1 i.v., b.i.d., dexamethasone 20 mg i.v., lorazepam and biperiden as well as training in relaxation, nutritional advice and continuity in nursing care. Controls (n = 34) received standard treatment (metoclopramide 10-20 mg i.v. or dixyracin 20 mg i.v.). The intensity and duration of nausea and vomiting were significantly lower and measures of quality of life higher for patients on the experimental ward during the three cycles that were studied. No significant changes in emesis were observed between the cycles. There was no correlation between emesis and any of the parameters of quality of life measured. The reliability and validity of nausea ratings are discussed and we suggest that an underreporting of nausea and vomiting might be common.

Adult↗
PubMed1992

Women with polycystic ovary syndrome wedge resected in 1956 to 1965: a long-term follow-up focusing on natural history and circulating hormones.

OBJECTIVE: To determine if the hormonal imbalance in women with polycystic ovary syndrome (PCOS) continues into and after menopause and to analyze factors constituting an increased risk for developing metabolic disorders. DESIGN: The study was a transectional retrospective cohort follow-up of patients with PCOS. SETTING: The women with PCOS were recruited from hospital clinics, and referents were randomized from a population study of women. PARTICIPANTS: Thirty-three women ages 40 to 59 years with ovarian histopathology typical of PCOS at wedge resection 22 to 31 years previously; 132 age-matched referents were analyzed. MAIN OUTCOME MEASURES: Clinical data were collected via a questionnaire supplemented with an interview in connection to a clinical examination that also included fasting venous sampling. RESULTS: Infertility, hirsutism, and oligomenorrhea were more common among the subjects with PCOS, but there was a considerable spontaneous restitution of cyclic regularity with time. Women with PCOS were more often hysterectomized and entered menopause later compared with referents. The hormone data show a typical profile for PCOS. Compared with referents women with PCOS showed marked increase in prevalence of central obesity, higher basal serum insulin concentrations, and a higher prevalence of diabetes mellitus and hypertension. CONCLUSION: Perimenopausal women with PCOS have an increased morbidity in hypertension and diabetes mellitus that adds to the classic symptoms, such as anovulation, hirsutism, and infertility.

Adult↗
PubMed1992

IgE antibodies to Pityrosporum orbiculare and Staphylococcus aureus in patients with very high serum total IgE.

Serum IgE antibodies were detected with the radioallergosorbent test (RAST) to a panel of allergens which included Pityrosporum orbiculare, Candida albicans, Trichophyton rubrum, Cladosporium herbarum, Staphylococcus aureus, animal dander, deciduous tree pollens, grass pollens and foods in 81 consecutive patients with total IgE greater than or equal to 3000 kU/l. Data on atopic and infectious disease characteristics were collected by a questionnaire. IgE antibody concentrations to P. orbiculare were significantly higher than to the other fungi and of the same magnitude as those to animal danders and pollens. High levels of P. orbiculare IgE antibodies were associated with current eczema, especially when it was the only atopic manifestation and demanding specialist care. IgE antibodies to P. orbiculare had the best explanatory value for current eczema in logistic regression analysis. Head-neck-face dermatitis was also associated with high levels of specific IgE to the yeast. IgE antibodies to S. aureus were detected in few patients and at low concentrations. Six patients had a history of systemic staphylococcal infections and presented a clinical picture, which was very similar to the hyperimmunoglobulinaemia E syndrome. Among the six were the two cases with the highest levels of IgE antibodies to S. aureus. The demonstration of high levels of IgE antibodies to P. orbiculare, which is a major part of human normal skin microflora, suggests that allergy to this yeast plays an important pathogenic role in eczema.

Adolescent↗
PubMed1992

Geographical variation and time trends in the attack rate of coronary heart disease in five Swedish cities.

Based upon community myocardial infarction (MI) records in five Swedish cities, geographical variation and time trends in the attack rate of fatal and non-fatal MI have been evaluated. During the study period 1975-1982, a total of 7699 events were registered among men and 1823 events among women. The mean annual mortality was highest in the north, and a declining gradient in mortality was observed from the northern to the southern part of the country. The out-of-hospital death rate was highest in the north, while no difference in in-hospital mortality was observed. However, the geographical variation in the morbidity of MI was less consistent. Changes over time generally followed the same pattern in all cities. The attack rate of fatal and non-fatal MI tended to decline among women and men aged 60-64 years. The pattern was less consistent among younger men. Among women aged 50-59 years the mortality remained unchanged, but the attack rate of non-fatal MI increased in all cities. This increase was not explained by inclusion of less severe infarctions. A considerable proportion, about 85%, were recorded as primary events, emphasizing the possible role of primary prevention in obtaining a decrease in the incidence of the disease. The results of this study support previous findings of an important regional difference in the mortality of MI in Sweden. However, the magnitude of the regional variation in the incidence of coronary heart disease might be overestimated if only the mortality pattern is studied.

Adult↗
PubMed1992

Impulses and resting membrane properties of small cultured rat hippocampal neurons.

1. The impulses and resting membrane parameters of small (soma diameter less than 10 microM) cultured hippocampal neurons from rat embryos were studied with the tight-seal whole-cell recording technique. 2. Mean resting potential was -47 mV, mean input resistance 3.3 G omega, mean capacitance 11 pF, and mean time constant 33 ms. 3. Rectangular suprathreshold current steps elicited regenerative potential responses. The amplitude and time course of the responses were clearly stimulus dependent: stronger current steps caused impulses of larger amplitude. 4. The current threshold was very low: rheobase current was less than 15 pA. 5. The potential response depended on the preceding holding potential, responses from more negative potentials showing sharper peaks than those from more positive potentials. 6. Spontaneous impulses with pre-potentials similar to synaptically induced events were recorded from several cells. The amplitude of the spontaneous impulses varied similarly to that of the stimulus-induced responses.

Action Potentials↗
PubMed1992

Membrane currents in small cultured rat hippocampal neurons: a voltage-clamp study.

1. The currents underlying the graded impulses in small cultured hippocampal neurons from rat embryos were analysed under voltage-clamp conditions with the tight-seal whole-cell recording technique. 2. The leak and capacitative currents induced by a potential step were linearly related to the potential in the range studied (-60 to -100 mV). 3. With steps to potentials more positive than -40 mV, at least two different potential-activated currents were detected: an initial transient current and a delayed sustained one. In addition, 40% of the cells studied showed a delayed transient current. 4. The initial transient current showed sigmoid activation and roughly exponential inactivation. Its reversal potential depended on the Na+ concentration and was close to the Na+ equilibrium potential. Further, it was blocked by 3.0 microM-tetrodotoxin, and was abolished when choline was substituted for Na+ in the extracellular solution. We concluded that this current was carried mainly by Na+ ions. 5. The delayed sustained current showed sigmoid activation and almost no inactivation within 40 ms. The reversal potential was close to the K+ equilibrium potential. We concluded that this current was carried mainly by K+ ions. 6. The delayed transient current was outward in the potential range studied (-50 to +120 mV) and did not depend on the pipette Cl- concentration. It was assumed that this current was carried mainly by K+ ions. 7. A quantitative description of the initial transient and the delayed sustained currents was developed on the basis of earlier descriptions of excitable membranes.

Animals↗
PubMed1992

Computed potential responses of small cultured rat hippocampal neurons.

1. The potential responses of small hippocampal neurons were computed on the basis of a previous mathematical description of the currents recorded under voltage-clamp conditions. 2. The computed action potentials were graded with respect to stimulus strength, in accordance with previous experimental findings. 3. The time course of the membrane currents and of the permeabilities and permeability variables during the impulse was computed for different stimulus intensities. 4. The effect of the membrane time constant on the impulse amplitude was investigated. It was concluded that the value of the time constant used was not per se sufficient to explain the amplitude variation of the impulse. 5. The effect of the magnitudes of the different potential-dependent permeabilities on the impulse amplitude was investigated. A Na+ permeability within a certain range caused impulses of variable amplitude, and this variability was affected by the K+ permeability.

Action Potentials↗
PubMed1992

Changes in cell surface expression of fibronectin and fibronectin receptor during liver regeneration.

The surface expression of fibronectin and its major integrin receptor in liver, integrin alpha 5 beta 1, was studied during liver regeneration after partial hepatectomy. Using immunoblotting, plasma membranes isolated from livers at different regeneration stages were found to contain 6- to 8-fold elevated levels of fibronectin, alpha 5 and beta 1 at 12-24 h after the operation. Normal levels were gradually restored during the following 8-9 days. The membrane-associated fibronectin lacked the ED-A domain, suggesting that it consisted of plasma fibronectin. A prominent fibronectin fragment (180 kDa) was present at 12-24 h after surgery, possibly reflecting turnover of the pericellular matrix during cell division. Indirect immunohistochemical staining of liver sections revealed beta 1 and fibronectin mainly in the sinusoidal region of the hepatocyte plasma membrane. The distribution was not markedly altered during liver regeneration. The results suggest that the fibronectin-mediated contacts between the cells and the extracellular matrix increase during the pre-replicative and proliferative phases of liver regeneration. The significance of these results for the growth and for the structure of the liver during regeneration and development is discussed.

Animals↗
PubMed1992

Polycystic ovary syndrome and risk for myocardial infarction. Evaluated from a risk factor model based on a prospective population study of women.

In order to estimate whether women with polycystic ovary syndrome (PCOS) have an increased risk of developing myocardial infarction, a risk factor model was applied on 33 women with PCOS and 132 age matched referents. The risk factor model was established from independent risk factors for myocardial infarction in a prospective population study of 1462 women in Göteborg, Sweden. The independent risk factors were age, manifest hypertension, manifest diabetes mellitus, central obesity measured as increased waist to hip circumference ratio and serum triglyceride concentration. A considerably increased risk (relative risk of 7.4) of developing myocardial infarction was observed for women with PCOS compared to age-matched referents. Since the risk factors include variables correlated to obesity, the results indicate that advice on dietary restriction is an important part of the treatment once the diagnosis is established.

Adult↗
PubMed1992

Pityrosporum ovale and atopic dermatitis in children and young adults.

Children aged 0-21 years, 60 children with atopic dermatitis (AD), 40 children with rhinoconjunctivitis and or asthma (RA) and 40 children with no atopic history (HC) were studied to evaluate the relationship between skin colonisation with Pityrosporum ovale and the occurrence of specific IgE antibodies to P. ovale. The following studies were done: culture for P. ovale, measurement of IgE antibodies to P. ovale (skin prick test, RAST), Candida albicans, and Cladosporium herbarum (RAST) and IgG antibodies to P. ovale. P. ovale could be cultured with about the same frequency in children and young adults with AD and age-matched children with or without other atopic manifestations. In spite of similar colonisation, IgE antibodies against P. ovale occur only in atopy and more frequently in children with AD than in those with other types of atopic disease.

Adolescent↗
PubMed1992

Aspects of patient care. Interviews with relapse-free testicular cancer patients in Stockholm.

Thirty-nine relapse-free testicular cancer patients were interviewed 1-6 years after completion of chemotherapy, in connection with a study of conditioned nausea. Some structured questions about experiences of diagnosis and treatment were included, but this report also summarizes spontaneously given information. The patients' first contact with a treatment setting appears to be an important determinant of the overall treatment experience. If resources are limited, they are used effectively if concentrated during the initial contact with the patient. Support from relatives and friends was reported as good for 90% of the men during treatment. Thirty-two distressing factors during the treatment period were mentioned; the most severe were nausea and vomiting. Other high-ranking factors were "being restricted for the infusion" and "the smell of food." There is a need for flexibility in ways to prepare and serve food on the ward. Some men argued for more information concerning the disease and chemotherapy; others said they received too much information. Several men suggested that a debriefing talk with the physician and someone from the staff should be arranged 6 months to 1 year after completion of treatment.

Adult↗