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Biomedical subjects

G Johansson

Publications and source records attributed to G Johansson.

At least 55 records · Page 3Linked to original sources
PubMed2001

Acute effects of angiotensin II on myocardial performance.

BACKGROUND: Specific angiotensin II (Ang II) receptors exist in many organs including peripheral blood vessels, cardiac myocytes and the central nervous system. This suggests multiple sites of actions for Ang II throughout the cardiovascular system. Cardiac effects of Ang II are not completely understood, though its prominent vasoconstrictor actions are well described. This study was designed to assess left ventricular function during administration of Ang II using relatively load-independent methods in a whole-animal model. METHODS: Ang II was infused in incremental doses (0-200 microg x h(-1)) in anaesthetised instrumented pigs (n=10). Cardiac systolic and diastolic function were evaluated by analysis of the left ventricular pressure-volume relationship. RESULTS: Heart rate (HR), mean arterial pressure (MAP) and systemic vascular resistance (SVR) increased dose-dependently with Ang II, while cardiac output (CO) remained unchanged. Systolic function indices, end-systolic elastance (Ees) and preload recruitable stroke work (PRSW), demonstrated dose-dependent increases. The diastolic function parameter tau (tau) did not change with increasing Ang II dose. CONCLUSION: Ang II infusion caused increases in contractility indices in anaesthetised pigs in the doses used in this study. The mechanisms for these systolic function effects may be a direct myocardial effect or modulated through changes in autonomic nervous system activity.

Angiotensin II↗
PubMed2001

Criminality and aggression among psychotic in-patients: frequency and clinical correlates.

OBJECTIVE: Violence is common among patients with psychoses. The aim of the study was to examine relations between diagnoses, crimes, demographic variables and aggressive behaviour during admission to hospital. METHOD: During 14 months 257 patients were consecutively referred to a unit with high staff/patient ratio. They were assessed for clinical symptoms at admittance and discharge. Also legal status, coercive measures, criminality and sentences were examined. RESULTS: Of the 257 patients, 38% were found in the police register and 33% had been prosecuted. Those patients committed 2525 crimes, including 292 acts of violence. Problems during admittance were related more to positive symptoms at admittance than to earlier criminality. CONCLUSION: Criminality rate is high among patients with functional psychoses. Many patients, especially women, had never been evaluated by a forensic psychiatrist. The psychiatric services have to consider the importance of preventing psychotic relapses and thereby also preventing violence and criminality.

Adolescent↗
PubMed2001

Mechanism of substrate inhibition in cellulose synergistic degradation.

A comprehensive experimental study of substrate inhibition in cellulose hydrolysis based on a well defined system is presented. The hydrolysis of bacterial cellulose by synergistically operating binary mixtures of cellobiohydrolase I from Trichoderma reesei and five different endoglucanases as well as their catalytic domains displays a characteristic substrate inhibition. This inhibition phenomenon is shown to require the two-domain structure of an intact cellobiohydrolase. The experimental data were in accordance with a mechanism where cellobiohydrolases previously bound to the cellulose by means of their cellulose binding domains are able to find chain ends by lateral diffusion. An increased substrate concentration at a fixed enzyme load will also increase the average diffusion distance/time needed for cellobiohydrolases to reach new chain ends created by endoglucanases, resulting in an apparent substrate inhibition of the synergistic action. The connection between the binding properties and the substrate inhibition is encouraging with respect to molecular engineering of the binding domain for optimal performance in biotechnological processes.

Cellulase↗
PubMed2001

Compliance with hormone replacement therapy among Swedish women.

By means of a simple postal questionnaire, all women registered as hormone therapy patients (n = 241) at a gynaecological clinic were screened for reasons for receiving hormone therapy. They were also screened for their compliance in following the midwife's advice and information, as well as the gynaecologist's prescriptions. The majority of the women participating in this study contacted the clinic for climacteric symptoms. The time duration for using hormone therapy ranged from 1 month to 6 years. Those using a plaster or gel were asked why they should take progesterone pills. Forty per cent gave erroneous answers or did not know. Of these, 62% reported that they understood the oral information, whereas 60% reported that they understood the written information. Fifty-three per cent of the women stated that they would stop their hormone therapy if they did not feel well or increased in weight. New discoveries or information about benefits or risks were given by 22% as reasons affecting their decision. Compliance demands well-motivated and well-informed patients. The implication of the study result for practice is that there must be dialogue between the women and their midwife/ gynaecologist. It is important that the women feel they are receiving treatment which they have given their consent to, and that they feel and know that they are performing self-care. Midwives have recurrent contact with women during their life and have already established a relationship with them, which facilitates an individualized communication.

Adult↗
PubMed2001

Underreporting of energy intake in repeated 24-hour recalls related to gender, age, weight status, day of interview, educational level, reported food intake, smoking habits and area of living.

OBJECTIVE: The aims of the present study were (1) to evaluate the degree to which underreporting of energy intake by repeated 24-hour recalls was related to gender, age, weight status, day of interview, educational level, smoking habits and area of living, and (2) to compare the dietary characteristics of underreporters with those of others. DESIGN: Cross-sectional study. Ten 24-hour recalls were performed during a one-year period. SETTING: The Västerbotten intervention programme of cardiovascular disease and diabetes in Northern Sweden. SUBJECTS: Ninety-four men and 99 women in four age groups: 30, 40, 50 and 60 years. RESULTS: The prevalence of men and women with a food intake level (FIL; reported energy intake divided by estimated basal metabolic rate) below 1.2 was 44% and 47%, respectively. The youngest age group had higher FIL values than the oldest age group for both men (1.5 versus 1.1) and women (1.4 versus 1.1). The prevalence and magnitude of underreporting were directly related to body mass index (BMI; correlation coefficient: -0.47 (men) and -0.55 (women)). Smokers had a lower FIL value (1.1) than non-smokers (1.3). The nutrient density was lower for the group with high FIL values for protein and calcium and higher for fat and sucrose. The upper FIL group often had higher intake frequencies and larger portion sizes than the lower FIL group. CONCLUSIONS: Underreporting of energy intake is prevalent when 24-hour recalls are used, but the prevalence differs between sub-groups in the population. BMI was the main predictor of underreporting but also old age and smoking seem to contribute in this aspect. Socially desirable food items were not underreported to the same extent as socially undesirable food items. The intake frequencies and portion sizes partly explained the differences in FIL.

Adult↗
PubMed2001

Food habits of young Swedish and Norwegian vegetarians and omnivores.

OBJECTIVE: To determine the prevalence of vegetarianism and compare food habits among vegetarian and omnivorous adolescents in Sweden and Norway. DESIGN: Cross-sectional study by questionnaire in Sweden and Norway to gather information about food habits. SETTING: The municipalities of Umeå and Stockholm in Sweden, and Bergen in Norway. SUBJECTS: In total 2041 ninth-grade students (578 from Umeå, 504 from Stockholm and 959 from Bergen), mean age 15.5 years, were included. The response rate was 95% in Umeå, 91% in Stockholm and 83% in Bergen. RESULTS: There was a significantly higher prevalence of vegetarianism in Umeå (15.6%) than in Stockholm (4.8%) and Bergen (3.8%). Vegetarians generally wanted more information about a healthy diet and vegetarian females ate dietary supplements to prevent deficiencies more often than omnivorous females (P < 0.01). The young male vegetarians more or less excluded animal products from their diet without changing their food frequency intake or modifying their dietary habits in other respects, while the young female vegetarians more often consumed vegetables and dietary supplements (P < 0.05). However, there was no difference between the intake of fruits/berries, alcoholic beverages, ice cream, sweets/chocolates and fast foods by vegetarians compared with omnivores. CONCLUSIONS: There were three to four times more vegetarians in Umeå than in Stockholm and Bergen. The food habits of the young vegetarians differed from those of omnivorous adolescents and also in some respects from previously published comparative studies of vegetarians' and omnivores' food habits. It is uncertain whether the health benefits shown in previous studies on vegetarianism will be experienced by this young generation of vegetarians.

Adolescent↗
PubMed2001

Effects of mouthrinses with linseed extract Salinum without/with chlorhexidine on oral conditions in patients with Sjögren's syndrome. A double-blind crossover investigation.

OBJECTIVES: To study the effect of mouthrinses with salivary replacement substances on oral conditions in patients with primary Sjögren's syndrome. DESIGN: Cross-over, double-blind study. SETTING: Facilities at the Centre for Oral Health Sciences, Malmö University and at Malmö University Hospital, Malmö, Sweden. SUBJECTS: Twenty-two patients with Sjogren's syndrome. INTERVENTION: Linseed extract Salinum alone (Sal) or with addition of chlorhexidine (Sal/Chx) was used for mouthrinsing during 3-week periods of rinsings separated by a 3-week "wash-out" period. MEASUREMENTS: Recordings of percentages of sites with dental plaque and bleeding on probing, mirror friction test and microbiological analyses. Questionnaire on oral symptoms due to reduced salivation. RESULTS: Dental plaque and bleeding on probing were reduced after Sal and after Sal/Chx. Friction was reduced after both treatments. No significant differences for counts of studied microbial groups were seen after Sal but the total anaerobically cultured microorganisms and of mutans streptococci fell after Sal/Chx (p<0.05 and p<0.001). Symptoms of oral dryness improved following Sal and Sal/Chx (p<0.05 and p<0.001 respectively). Speaking problems and burning mouth symptoms improved after use of Sal (p<0.05). CONCLUSIONS: Positive effects on symptoms in patients with Sjögren's syndrome were seen after use of Salinum without or with chlorhexidine.

Adult↗
PubMed2000

Cellobiohydrolase 58 (P.c. Cel 7D) is complementary to the homologous CBH I (T.r. Cel 7A) in enantioseparations.

Cellobiohydrolase 58 (EC 3.2.1.91, P.c. Cel 7D) from Phanerochaete chrysosporium was immobilized on silica and the resulting material, CBH 58-silica, was then used as a chiral stationary phase (CSP) in liquid chromatographic separations of enantiomers. The enantioselectivities obtained on CBH 58-silica were compared with those on CBH I-silica (a phase based on a corresponding cellulase from Trichoderma reesei). CBH 58-silica displayed higher selectivity than CBH I-silica for the more hydrophilic compounds, such as atenolol and metoprolol, although great similarities in chiral separation of beta-adrenergic antagonists were found between the two phases. None of the acidic compounds tested could be resolved on the CBH 58 phase. Moreover, the solutes were retained more on the CBH 58 phase in general, indicating an improved application potential in bioanalysis. Addition of cellobiose or lactose, both of which are inhibitors of cellulases, to the mobile phase impaired the enantioselectivity, indicating an overlap of the enantioselective and catalytic sites. The chiral analytes also functioned as competitive inhibitors and their inhibition constants were determined.

Cellulase↗
PubMed2000

Polygalacturonase is the key component in enzymatic retting of flax.

Seven commercial enzyme mixtures were tested for their ability to perform retting of flax (i.e. to separate flax fibers by partly removal of middle lamella) and were assayed for hydrolysis of xylan, cellulose and four kinds of pectin. The only activity that showed correlation to the ability to perform retting was the degradation of low esterfied pectin. A purified Aspergillus niger polygalacturonase was also shown to be able to perform retting. From this data it is hypothesized that degradation of the smooth regions (i.e. non-methylated polygalacturonase) in the middle lamella pectin is the most important step in enzymatic retting.

Edetic Acid↗
PubMed2000

Do the extracellular enzymes cellobiose dehydrogenase and manganese peroxidase form a pathway in lignin biodegradation?

The extracellular enzyme manganese peroxidase is believed to degrade lignin by a hydrogen peroxide-dependent oxidation of Mn(II) to the reactive species Mn(III) that attacks the lignin. However, Mn(III) is not able to directly oxidise the non-phenolic lignin structures that predominate in native lignin. We show here that pretreatment of a non-phenolic lignin model compound with another extracellular fungal enzyme, cellobiose dehydrogenase, allows the manganese peroxidase system to oxidise this molecule. The mechanism behind this effect is demethoxylation and/or hydroxylation, i.e. conversion of a non-phenolic structure to a phenolic one, mediated by hydroxyl radicals generated by cellobiose dehydrogenase. This suggests that cellobiose dehydrogenase and manganese peroxidase may act in an extracellular pathway in fungal lignin biodegradation. Analytical techniques used in this paper are reverse-phase high-pressure liquid chromatography, gas chromatography connected to mass spectroscopy and UV-visible spectroscopy.

Anisoles↗
PubMed2000

Is cellobiose dehydrogenase from Phanerochaete chrysosporium a lignin degrading enzyme?

Cellobiose dehydrogenase (CDH) is an extracellular redox enzyme of ping-pong type, i.e. it has separate oxidative and reductive half reactions. Several wood degrading fungi produce CDH, but the biological function of the enzyme is not known with certainty. It can, however, indirectly generate hydroxyl radicals by reducing Fe(3+) to Fe(2+) and O2 to H2O2. Hydroxyl radicals are then generated by a Fenton type reaction and they can react with various wood compounds, including lignin. In this work we study the effect of CDH on a non-phenolic lignin model compound (3,4-dimethoxyphenyl glycol). The results indicate that CDH can affect lignins in three important ways. (1) It breaks beta-ethers; (2) it demethoxylates aromatic structures in lignins; (3) it introduces hydroxyl groups in non-phenolic lignins. The gamma-irradiated model compound gave a similar pattern of products as the CDH treated model compound, when the samples were analyzed by HPLC, suggesting that hydroxyl radicals are the active component of the CDH system.

Carbohydrate Dehydrogenases↗
PubMed2000

Study on heterogeneity of beta-glucosidase from Aspergillus species by using counter-current distribution.

beta-Glucosidase plays a key role in cellulose degradation by cleaving its cellobiose units to glucose. The heterogeneity of the enzyme has been studied earlier by isoelectric focusing and several isoforms were found in the culture filtrate of Trichoderma and Aspergillus species. An aqueous two-phase system is an alternative fractionation method in which proteins are separated according to their net charge and surface properties. A dextran 500-poly(ethylene glycol) 8000 system was used to study the distribution of beta-glucosidase of different origins. To investigate the heterogeneity of enzymes 56- and 145-step thin-layer counter-current distributions were carried out. beta-Glucosidase produced by Aspergillus niger and Aspergillus carbonarius has been shown to consist of at least three isoenzymes by applying this method. The three forms of A. niger show the corresponding partition ratios with G values of 0.13, 0.22 and 0.31; and A. carbonarius 0.14, 0.22 and 0.36, respectively. However, the relative amount of these isoforms differs strongly between the two microorganisms.

Aspergillus↗
PubMed2000

Partitioning of peptides and recombinant protein-peptide fusions in thermoseparating aqueous two-phase systems: effect of peptide primary structure.

Genetic engineering has been used for fusion of peptides, with different length and composition, on a protein to study the effect on partitioning in an aqueous two-phase system. The system was composed of dextran and the thermoseparating ethylene oxide-propylene oxide random copolymer, EO30P070. Peptides containing tryptophan, proline, arginine or aspartate residues were fused at the C-terminus of the recombinant protein ZZ-cutinase. The aim was to find effective tags for the lipolytic enzyme cutinase for large-scale extraction. The target protein and peptide tags were partitioned separately and then together in the fusion proteins in order to gain increased understanding of the influence of certain amino acid residues on the partitioning. The salt K2SO4 was used to reduce the charge dependent salt effects on partitioning and to evaluate the contribution to the partition coefficient from the hydrophobic-hydrophilic properties of the amino acid residues. The effect of Trp on peptide partitioning was independent of the difference in primary structure for (Trp)n, (Trp-Pro)n, (Ala-Trp-Trp-Pro)n and was only determined by the number of Trp. The effect of the charged residues, Arg and Asp, was dependent on the surrounding residues, i.e. if they were situated next to Trp or not. The partitioning behaviour observed for the peptides was qualitatively and in some cases also quantitatively the same as for the fusion proteins. The effect of the salts sodium perchlorate and triethylammonium phosphate on the partitioning was also studied. The salt effects observed for the peptides were qualitatively similar to the effects observed for the fusion proteins.

Amino Acid Sequence↗
PubMed2000

Heat-shrinking spherical and columnar supramolecular dendrimers: their interconversion and dependence of their shape on molecular taper angle

Synthesis and modes of self-assembly are described for the tapered monodendritic molecules 3,4,5-nGi-X of generation i = 1, 2, 3 (see structures below) that contain multiple (CH2)nH alkyl chains on their periphery (n = 12, 14, 16) and a polar group X at the apex (X = COOH, COONa, COOCs, CO(OCH2CH2)3OH). These monodendrons self-assemble into supramolecular cylindrical or spherical dendrimers, which in turn self-organise into p6mm columnar or Pm3n cubic thermotropic liquid crystals, respectively. The two principal ways of affecting the self-assembly of these compounds by means of their molecular architecture are: a) by changing the width of the wide (aliphatic) end, and b) by changing the volume at the apex. In the present work a) is controlled through temperature (conformational disorder) and b) is controlled by chaging the generation number i or the size of X, for example, through the choice of metal cation. The single most important geometric parameter of these dendritic building blocks is the molecular solid angle (taper angle) alpha; a high alpha leads to spherical and a low alpha to cylindrical supramolecular dendrimers. Furthermore, alpha also determines the equilibrium size of the supramolecular objects; a larger alpha results in a smaller diameter. The unusually strong negative thermal expansion coefficient of the cubic and columnar lattice is attributed to the excess of the increasingly highly tapered molecules being rejected from their parent aggregates and reassembling as new ones. Increasing alpha is also considered to be responsible for the observed thermotropic columnar-cubic transition.

Journal Article↗
PubMed2000

A critical review of cellobiose dehydrogenases.

Cellobiose dehydrogenase (CDH) is an extracellular enzyme produced by various wood-degrading fungi. It oxidizes soluble cellodextrins, mannodextrins and lactose efficiently to their corresponding lactones by a ping-pong mechanism using a wide spectrum of electron acceptors including quinones, phenoxyradicals, Fe(3+), Cu(2+) and triiodide ion. Monosaccharides, maltose and molecular oxygen are poor substrates. CDH that adsorbs strongly and specifically to cellulose carries two prosthetic groups; namely, an FAD and a heme in two different domains that can be separated after limited proteolysis. The FAD-containing fragment carries all known catalytic and cellulose binding properties. One-electron acceptors, like ferricyanide, cytochrome c and phenoxy radicals, are, however, reduced more slowly by the FAD-fragment than by the intact enzyme, suggesting that the function of the heme group is to facilitate one-electron transfer. Non-heme forms of CDH have been found in the culture filtrate of some fungi (probably due to the action of fungal proteases) and were for a long time believed to represent a separate enzyme (cellobiose:quinone oxidoreductase, CBQ). The amino acid sequence of CDH has been determined and no significant homology with other proteins was detected for the heme domain. The FAD-domain sequence belongs to the GMC oxidoreductase family that includes, among others, Aspergillus niger glucose oxidase. The homology is most distinct in regions that correspond to the FAD-binding domain in glucose oxidase. A cellulose-binding domain of the fungal type is present in CDH from Myceliophtore thermophila (Sporotrichum thermophile), but in others an internal sequence rich in aromatic amino acid residues has been suggested to be responsible for the cellulose binding. The biological function of CDH is not fully understood, but recent results support a hydroxyl radical-generating mechanism whereby the radical can degrade and modify cellulose, hemicellulose and lignin. CDH has found technical use in highly selective amperometric biosensors and several other applications have been suggested.

Carbohydrate Dehydrogenases↗
PubMed2000

Partitioning and concentrating biomaterials in aqueous phase systems.

Aqueous phase separation is a general phenomenon which occurs when structurally distinct water-soluble macromolecules are dissolved, above certain concentrations, in water. The number of aqueous phases obtained depends on the number of such distinct macromolecular species used. Aqueous two-phase systems, primarily those containing poly(ethylene glycol) and dextran, have been widely used for the separation of biomaterials (macromolecules, membranes, organelles, cells) by partitioning. The polymer and salt compositions and concentrations chosen greatly affect the physical properties of the phases. These, in turn, interact with the physical properties of biomaterials included in the phases and affect their partitioning. Specific extractions of biomaterials can be effected by including affinity ligands in the systems. The phase systems can also be used to obtain information on the surface properties of materials partitioned in them; to study interactions between biomaterials; and to concentrate such materials.

Animals↗
PubMed2000

Cutaneous sympathetic vasoconstrictor reflexes for the evaluation of interscalene brachial plexus block.

BACKGROUND: Although signs of sympathetic blockade following interscalene brachial plexus block include Horner's syndrome, increased skin temperature and vasodilatation, the degree of sympathetic blockade is not easily determined. The aim of this study was, therefore, to use activation of cutaneous finger pad vasoconstrictor reflexes for description and quantification of the degree of sympathetic blockade following unilateral interscalene brachial plexus block. METHODS: Eight patients scheduled for acromioplasty under general anesthesia were studied. An interscalene plexus catheter was inserted preoperatively on the side to be operated upon and used postoperatively for administration of bupivacaine, given as a bolus (1.25 mg kg(-1)) followed by a continuous infusion (0.25 mg kg(-1) h(-1)). Skin blood flow (SBF) in the pad of the index finger was assessed by the laser Doppler technique, and regional skin vascular resistance (RVR) was calculated. The inspiratory gasp test (apnea at end-inspiration) or a local heat provocation were used as provocations of the cutaneous microcirculation. RESULTS: Interscalene brachial plexus block increased SBF and decreased RVR at rest, and produced satisfactory sensory and motor block. The inspiratory gasp test decreased SBF and increased RVR in the unblocked arm, while the opposite, increased SBF and decreased RVR, were observed during local heat provocation. In the blocked arm, these gasp-induced cutaneous vasoconstrictor and heat-induced vasodilator responses were attenuated. CONCLUSIONS: Interscalene brachial plexus block reduces regional sympathetic nervous activity, illustrated by increases in skin blood flow, skin temperature and attenuated vasoconstrictor responses to an inspiratory gasp. The inspiratory gasp vasoconstrictive response is a powerful and sensitive indicator for monitoring the sympathetic blockade following interscalene brachial plexus block.

Adult↗