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Biomedical subjects

G Johansson

Publications and source records attributed to G Johansson.

At least 253 records · Page 14Linked to original sources
PubMed1988

EGIII, a new endoglucanase from Trichoderma reesei: the characterization of both gene and enzyme.

A novel endoglucanase from Trichoderma reesei, EGIII, has been purified and its catalytic properties have been studied. The gene for that enzyme (egl3) and cDNA have been cloned and sequenced. The deduced EGIII protein shows clear sequence homology to a Schizophyllum commune enzyme (M. Yaguchi, personal communication), but is very different from the three other T. reesei cellulases with known structure. Nevertheless, all the four T. reesei cellulases share two common, adjacent sequence domains, which apparently can be removed by proteolysis. These homologous sequences reside at the N termini of EGIII and the cellobiohydrolase CBHII, but at the C termini of EGI and CBHI. Comparison of the fungal cellulase structures has led to re-evaluation of hypotheses concerning the localization of the active sites.

Amino Acid Sequence↗
PubMed1988

Separation of hemagglutinin and neuraminidase from influenza virus membrane by column displacement electrophoresis (isotachophoresis) with preservation of their activities.

Triton X-100-solubilized membrane glycoproteins (neuraminidase and hemagglutinin) from purified equine influenza virus particles were separated by column displacement electrophoresis (isotachophoresis) in the presence of Pharmalyte spacers. Electrophoresis was performed in a 1.80 cm glass electrophoresis column with Sephadex G-25 Fine serving as supporting medium. Triton X-100 was present in the system to suppress protein aggregation. Neuraminidase and hemagglutinin activities were preserved and appeared in the electropherogram as separate peaks with some overlapping.

Cell Membrane↗
PubMed1988

Muscle function and morphology in myotonic dystrophy.

Patients with myotonic dystrophy classified clinically into function groups were studied. Muscle strength for knee extension and flexion was, with few exceptions, moderately or markedly reduced with successively more severe clinical disability. The reduction in maximal walking speed showed a similar tendency. There was a large percentage of both type I and in relation to normal findings of type II C fibers in biopsies from most patients. The fiber area varied greatly even in the patients in the best function groups, some of whom had large type II fibers. The most common-histopathological changes, found in all function groups, were fiber atrophy with small angular fibers, internal nuclei, splitting, fibrosis and moth-eaten fibers. A high percentage of type I fibers can already be seen in patients with practically no other morphological changes and without significant functional deterioration.

Adult↗
PubMed1988

Disordered catecholamine release in pigs susceptible to malignant hyperthermia.

Pigs, crossbreeds of Swedish Landrace and Yorkshire, females and castrated males about 6 months old, were exposed to experimental stress. The pigs were either considered normal or shown to be susceptible to develop malignant hyperthermia when tested with halothane at about 6 weeks of age (stress-susceptible pigs). The stress was of the restraint type, produced by two different myorelaxant agents, the depolarizing succinylcholine or the non-depolarizing pancuronium. The blood levels of the catecholamines (CA) noradrenaline (NA) and adrenaline (A) were measured during the stress. The severity of myocardial cell necrosis observed 1 to 2 days after the stress was morphologically graded. In normal pigs the levels of NA during the stress and the degree of myocardial cell necrosis were about the same after both succinylcholine and pancuronium. In stress-susceptible pigs, however, succinylcholine produced very high NA and A levels and severe heart lesions, whereas after pancuronium the NA and A levels were rather low and the heart lesions significantly reduced when compared to those after succinylcholine-induced stress. After pretreatment with dantrolene intravenously the succinylcholine-induced stress only induced slightly increased blood CA levels and no signs of myocardial cell necrosis in pigs susceptible to develop malignant hyperthermia. Dantrolene, an efficient drug in treatment of malignant hyperthermia, probably acts by interfering with release of calcium from the sarcoplasmic reticulum in skeletal muscles. The results indicate that peripheral sympathetic neurones in MHS pigs also react abnormally, probably due to defective calcium turn-over.

Animals↗
PubMed1988

Twenty-four-hour patterns of pineal melatonin and pituitary and plasma prolactin in male rats under 'natural' and artificial lighting conditions.

Natural lighting differs from usual artificial lighting mainly as follows: it has larger spectral composition, fluctuations of intensity during the day, higher intensity levels during the night (moonlight, starlight), and gradual changes of illuminance at dawn and dusk. The present experiment was performed in order to study whether these features of lighting affect the 24-hour patterns of melatonin and prolactin in male rats. The rats were kept 7 days in 'natural' lighting (sunlight through windows) or in artificial lighting (cool white fluorescent lamps) of similar periodicities (13/11 h light/dark). The samples were collected at 3-hour intervals during a 24-hour period. Pineal melatonin contents, pituitary prolactin contents, and plasma prolactin concentrations were measured radioimmunologically. The nocturnal pineal melatonin contents were higher and the daytime contents lower in natural than in artificial lighting conditions. A corresponding 'strengthening of rhythm' of prolactin was found in natural lighting. A reason for the higher amplitude variation of melatonin in the natural lighting conditions may be the gradual changes of illuminance at dawn and dusk. The different pituitary and plasma prolactin patterns of the rats kept in the two lighting conditions might partly be explained by a stimulatory effect of melatonin on the production and secretion of prolactin, but other regulatory factors had to be involved, too.

Animals↗
PubMed1988

Prevention of renal stones by a high fluid intake?

From the physiochemical view on the formation of urolithiasis a high fluid intake, provided it resulted in a high urine volume, should reduce the propensity of crystallization, crystal growth and stone formation. This critical review of the literature, however, demonstrates that there is little epidemiologic support for the hypothesis that a low urine volume is an important risk factor for renal stones in temperate climates. Few clinical studies have attempted to elucidate if a large diuresis can prevent further stone formation in a recurrent renal stone former. In the present study 115 recurrent stone formers were followed for an average period of 6 years without any other treatment than advice about a high fluid intake. The annual recurrence rate was around 23% but there was no difference between those who maintained a high urine volume and those who did not. Thus, the available evidence does not indicate that variations of fluid intake markedly affect stone formation.

Diuresis↗
PubMed1987

Effect of polymer structure on affinity partitioning of lactate dehydrogenase in polymer-water two-phase systems.

Lactate dehydrogenase from rabbit muscle (EC 1.1.1.27) was partitioned between the liquid phases of aqueous two-phase systems containing two kinds of polymers. The partition was influenced by the use of a dye ligand, Procion Yellow HE-3G, bound to a polymer. The ligand-carrying polymers were poly(ethyleneglycol), poly(vinyl alcohol), ethylhydroxyethylcellulose, hydroxypropyl-starch, Ficoll and dextran. Their influence on the partition of lactate dehydrogenase was studied in systems composed of the following pairs of polymers: dextran-poly(ethylene glycol), dextran-poly(vinyl alcohol), dextran-Ficoll and hydroxypropyl-starch-poly (ethylene glycol). The ratio between the change in the logarithmic partition coefficient of the enzyme, delta log K, caused by the ligand and the logarithm of the partition coefficient of the ligand-polymer, log KL-polymer, was used as a measure of the number of ligand polymers bound per enzyme molecule under saturation conditions. Possible explanations for the observed effects are discussed.

Animals↗
PubMed1987

Preparative displacement electrophoresis (isotachophoresis) of proteins on cellulose columns.

This paper describes the separation of proteins by displacement electrophoresis on columns packed with cellulose powder as a stabilizing medium. Cellulose has virtually no molecular sieving properties and thus differs from dextran, polyacrylamide, and agarose in this respect. Therefore, without the risk of unstacking, columns packed with cellulose permit conventional elution of the protein zones and the use of a counter flow (to increase the effective length of the bed). For the same reason, electroosmotic flow is less disturbing. A continuous elution-migration technique adapted to suit the special requirements of displacement electrophoresis gave better separation than was obtainable by conventional elution. Normal human serum and a fresh hemolysate from human erythrocytes were used as samples. An expression for the volume velocity of the boundaries is derived. This parameter can be used to determine the maximum duration of a run and a suitable pump speed when continuous elution or a counter flow is employed. The special advantages of displacement electrophoresis in cellulose beds are discussed as well as general disadvantages of the displacement technique, including the risk that proteins precipitate during a run.

Blood Protein Electrophoresis↗
PubMed1987

Enzyme electrodes and their application.

Starting from the state of the art, principles for improving the analytical characteristics of enzyme electrodes are discussed. Coupling of appropriate amperometric electrode processes with enzyme systems, e.g. urease or aminopeptidases, results in a simplification of operation. Optimal sample frequencies are realized on the basis of enzyme membranes, with both a small characteristic diffusion time and a high enzyme activity, applied in a well-designed sample-processing system. Coupled enzyme reactions of the sequence or competition type are successfully used for extension to new analytes, e.g. inhibitors, cofactors or alternative substrates. Cyclization of the analyte enhances the sensitivity of enzyme electrodes to the nanomolar concentration range. Enzymic anti-interference layers are a tool for improving the sensor specificity. The operational characteristics of enzyme electrodes are thus adaptable to any given analytical problem.

Biotechnology↗
PubMed1987

Affinity partitioning of enzymes using dextran-bound procion yellow HE-3G. Influence of dye-ligand density.

The dye Procion Yellow HE-3G was bound to dextran of molecular weight 70,000 and the partitioning of this dye-polymer within an aqueous two-phase system containing dextran and poly(ethylene glycol) was studied as function of ligand density, polymer concentration, type of salt, concentration of salt and concentration of dye-dextran. Even moderate dye:dextran molar ratios (5-8) make the partitioning strongly salt-dependent. The dye-dextran can be directed to either the upper or the lower phase with partition coefficients from 0.02 to 28 by using salts. The dye-dextran in the two-phase system affects the partitioning of dye-binding enzymes (lactate dehydrogenase, glucose-6-phosphate dehydrogenase, 3-phosphoglycerate kinase) towards the dye-containing phase. Measurements of competition with nucleotide binding show an increased affinity of the dye for the enzyme with increasing ligand:dextran ratio. Theoretical considerations indicate that 1-2 dextran molecules are attached per enzyme molecule when affinity partitioning is fully developed.

Chromatography, Affinity↗
PubMed1987

Effects of organic solvents on the partitioning of enzymes in aqueous two-phase systems.

Organic solvents (ethylene glycol, glycerol, dimethyl sulphoxide, dimethylformamide, dioxane, methanol and propanol-2, as well as sucrose and urea) have been included in aqueous two-phase (liquid-liquid) systems comprised of water, dextran and poly(ethylene glycol). The concentration of the organic solvent was in most cases 20% (w/w). The influence of these solvents on the phase-forming properties, the volume ratio, the freezing point and the partitioning of a polymer-bound ligand, Procion Red HE-3B poly(ethylene glycol), has been studied. The partition coefficients for alkaline phosphatase decrease with ethylene glycol, glycerol, sucrose and urea (factors of 0.25-0.5), but increase with the other substances (factors of 1.2-1.6). The temperature effects on the partitioning of alkaline phosphatase from calf intestine as well as of phosphofructokinase from yeast in systems containing ethylene glycol have been studied and compared with partitioning in standard systems, not containing solvents. The possible uses of the above systems for partitioning studies of enzymes are discussed.

Alkaline Phosphatase↗
PubMed1987

Catecholamine-induced free radicals in myocardial cell necrosis on experimental stress in pigs.

Normal pigs, crossbreeds of Swedish Landrace and Yorkshire, about 6 months old, were subjected to experimental stress, induced by the myorelaxant succinylcholine, for 12 min. Besides one group of control pigs, one group of pigs were pretreated with alpha-tocopherol (vitamin E) combined with selenium (Tokosel Vet) injected i.m. every second day for 11 days, and another group was given zinc (ZnSO4.7H2O) in the fodder for 1 month plus one injection i.p. 2 days before the stress. The stress-induced heart lesions, morphologically graded according to evaluation scores, were significantly reduced in both the pretreated groups when compared with the control pigs. The blood levels of catecholamines (CA) were increased to about the same degree in the three groups during the stress. The protection observed is suggested to be due to the fact that vitamin E, selenium and zinc are involved in systems acting as scavengers of free radicals. The present results together with earlier ones are discussed to support the CA-hypothesis for stress-induced heart lesions: some types of stress can increase the sympathetic activity to such an extent that released CA, via beta-adrenoceptor mechanisms affects the cell metabolism to such a degree that cytotoxic free radicals are formed, producing myocardial cell necrosis.

Animals↗
PubMed1987

Spectral properties of light affect plasma and pituitary gonadotropins in male rats.

In order to find out whether different light spectra have any role in regulating the gonadotropin levels in male rats, we compared the 24-hour patterns of plasma and pituitary gonadotropins in rats kept for 7 days in natural or in cool white artificial lighting (exp. I). The intensity and periodicity of the two lighting conditions were adjusted as similar as possible. Further, we measured plasma and pituitary gonadotropins in the middle of the light period and in the middle of the dark period in rats kept for 7 days under artificial lightings of three different spectra (exp. II). In both experiments, in all lighting conditions we found higher plasma levels of LH and FSH during the dark than the light period. The differences were statistically significant only when the illumination contained more long and/or short wavelengths than the usual cool white laboratory lighting. The pituitary contents of gonadotropins were not found to vary with the periodicity of lighting. In the 24-hour patterns the overall plasma levels were higher and the pituitary contents of gonadotropins lower in natural lighting than in cool white lighting. It was concluded that the spectral properties of light influence the secretion of gonadotropins in male rats, but the mechanism involved remains to be clarified.

Animals↗
PubMed1987

Pain and stress: correlation of stress hormone release to pain modulation in man.

The contribution of stress-induced and opioid-dependent mechanisms to the modulation of experimental pain was studied in man under different conditions. The contribution of these mechanisms to the possible attenuation of acute cardiac pain in human patients was also studied. According to the present series of investigations, stress-induced mechanisms might be involved in the modulation of pain caused by physical exercise but not by concurrent subacute pain or transcutaneous nerve stimulation. The lack of any negative correlation between the pain intensity and the release of stress hormones indicates that stress mechanisms do not attenuate acute ischaemic pain of the cardiac origin. The use of an opioid-antagonist, naloxone, and the measurement of plasma levels of beta-endorphin did not reveal any contribution of endogenous opinoids to pain modulation in the current study.

Coronary Disease↗
PubMed1987

Eye motility dysfunction in chronic primary fibromyalgia with dysesthesia.

Thirty-six patients with "chronic primary fibromyalgia" combined with dysesthesia were studied using oculomotor tests. The test results were compared with those of a control group consisting of 71 healthy persons. The saccades were found to be abnormal in 42% of the patients studied. The maximum velocity of the saccades was often reduced, while the accuracy was normal. The smooth pursuit eye movements were deranged in 89% of the patients. The velocity gain was reduced and the number of corrective saccades was increased. The results indicate that brain dysfunction, often at the brainstem level, is commonly seen in patients with chronic primary fibromyalgia syndrome combined with dysesthesia.

Adult↗