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Biomedical subjects

G Johansson

Publications and source records attributed to G Johansson.

At least 73 records · Page 4Linked to original sources
PubMed2000

Surgical stress induces acute coronary release of tissue-type plasminogen activator in the pig.

BACKGROUND: Tissue-type plasminogen activator (t-PA) is an endothelium derived key enzyme in the initiation of endogenous fibrinolysis. Acute regulated release of active t-PA occurs within minutes in response to threatening thrombotic vessel occlusion. The aim of this study was to investigate the impact of surgical stimulation on the kinetics of t-PA release in the coronary vascular bed in the pig. METHODS: In anaesthetised pigs (n=16), arterio-venous concentration gradients of t-PA, and plasma flows (retrograde thermodilution) were obtained across the coronary vascular bed before (control) and at 1, 3, 5 and 10 min after sternotomy. RESULTS: At control, no significant coronary net flux (release or uptake) of t-PA was observed, while sternotomy induced a rapid net release of total t-PA (132.6 ng x min(-1)), with an associated increase in active t-PA (93.6 ng x min(-1)). This response, evident already after 1 min, showed a peak at 5 min and returned towards baseline levels within 10 min. No concurrent alterations in aortic levels of active t-PA were found and haemodynamic variables were unaltered. CONCLUSION: The rapidly increasing and transient net coronary release of t-PA after sternotomy suggests that the endothelium actively promotes local endogenous fibrinolysis during surgery. Such events could reflect a dynamic responsiveness to protect the coronary circulation during stress.

Animals↗
PubMed2000

Angiotensin II mesenteric and renal vasoregulation: dissimilar modulatory effects with nitroprusside.

BACKGROUND: The role of systemic arterial pressure for the vascular effects of angiotensin II (Ang II) and the interactions between Ang II and perfusion pressure-dependent local vascular control mechanisms are not well understood. This study addresses these aspects of exogenous Ang II in the mesenteric and renal regional circulations. METHODS: Ang II was infused in incremental doses (0-200 microg/h) in anesthetized instrumented pigs (n=10). Renal and portal blood flows were measured by perivascular ultrasound. In the second part of the study, sodium nitroprusside (SNP) was infused at doses titrated to keep mean arterial pressure constant, in spite of concurrent Ang II administration. RESULTS: Powerful dose-dependent vasoconstrictions by Ang II were found in renal and mesenteric vascular beds (at highest Ang II doses vascular resistances increased by 109% and 88% respectively). Ang II-induced vasoconstriction was fully inhibited in the mesenteric, but not in the renal circulation, during conditions of constant mean arterial pressures achieved by SNP infusion. CONCLUSIONS: Mesenteric, but not renal, vasoconstriction by Ang II was inhibited by pharmacological maintenance of perfusion pressure. This could reflect differences between these vascular beds as regards the importance of co-acting myogenic pressure-dependent vasoconstriction. Alternatively, as the drug chosen for pressure control, sodium nitroprusside, serves as a nitric oxide donor, the relative balance between nitric oxide-mediated vasodilation and Ang II-induced vasoconstriction could have regional differences.

Angiotensin II↗
PubMed2000

Assessment of myocardium at risk in pigs with single photon emission computed tomography and computerized vectorcardiography during transient coronary occlusion.

Since myocardium at risk (MAR) is the major prognosticator of final infarct size and outcome in patients with acute myocardial infarction, it is highly desirable to estimate the size of the acutely ischemic myocardium, that is the MAR, in these patients. We assessed MAR size by Tc-99m-sestamibi-SPECT and computerized vectorcardiography using autoradiography as reference method. Transient myocardial ischemia was achieved in 12 pigs by coronary artery occlusion with PTCA catheters. During the procedure, computerized vectorcardiography was continuously recorded. After injection of Tc-99m-sestamibi and gadolinium-153-labelled microspheres, MAR size was estimated by SPECT and post-mortem autoradiography. Different cut-off levels (50-70%) were compared with respect to MAR-SPECT. Tc-99m-sestamibi-SPECT showed a good correlation with autoradiography (r = 0.94). Computerized vectorcardiography showed a good correlation with autoradiography as well as with Tc-99m-sestamibi-SPECT (STC-VM: r = 0.75 and 0.80, respectively, ST-VM: 0.75 and 0.87, respectively). It was found that 1) MAR assessed by Tc-99m-sestamibi-SPECT correlates closely with the autoradiographic reference; 2) a lower cut-off point of 60% of maximum uptake for MAR by Tc-99m-sestamibi-SPECT gives the closest correlation with the autoradiographic reference; and 3) ST-VM and STC-VM correlate well with MAR assessed by Tc-99m-sestamibi-SPECT and autoradiography.

Animals↗
PubMed2000

Design and evaluation of a software prototype for participatory planning of environmental adaptations.

A software prototype to support the planning process for adapting home and work environments for people with physical disabilities was designed and later evaluated. The prototype exploits low-cost three-dimensional (3-D) graphics products in the home computer market. The essential features of the prototype are: interactive rendering with optional hardware acceleration, interactive walk-throughs, direct manipulation tools for moving objects and measuring distances, and import of 3-D-objects from a library. A usability study was conducted, consisting of two test sessions (three weeks apart) and a final interview. The prototype was then tested and evaluated by representatives of future users: five occupational therapist students, and four persons with physical disability, with no previous experience of the prototype. Emphasis in the usability study was placed on the prototype's efficiency and learnability. We found that it is possible to realise a planning tool for environmental adaptations, both regarding usability and technical efficiency. The usability evaluation confirms our findings from previous case studies, regarding the relevance and positive attitude towards this kind of planning tool. Although the prototype was found to be satisfactorily efficient for the basic tasks, the paper presents several suggestions for improvement of future prototype versions.

Activities of Daily Living↗
PubMed2000

Oral mucous membrane flora in patients using saliva substitutes.

UNLABELLED: Salivary substitutes are sometimes valuable for elderly people and radiotherapy patients, and may be used indefinitely. It is possible that this change in the ecology may effect the oral flora. OBJECTIVE: To analyse the presence of micro-organisms on oral mucous membranes during use of saliva substitutes. DESIGN: Cross-over single-blind study. SETTING: Clinic for Maxillofacial Surgery, Malmö University Hospital and Department of Oral Microbiology, Malmö University. SUBJECTS: 19 patients with low salivary secretion who had been radiated for cancer in the head and neck region. INTERVENTION: Two saliva substitutes: linseed extract and a carboxymethyl cellulose preparation (Salinum and MAS-84) were used for 3 week periods. MEASUREMENTS: Microbial samples taken, processed and analysed. RESULTS: No differences were observed when comparing baseline values with the results after the saliva substitutes and no significant differences between the use of different agents. CONCLUSION: The study suggests that use of linseed extract and carboxymethyl cellulose preparation during periods of weeks does not influence flora commonly related to caries, periodontitis or infections in the oral mucous membranes.

Adult↗
PubMed2000

Muscle sizes and moment arms of rotator cuff muscles determined by magnetic resonance imaging.

Biomechanical models which require information on, e.g., joint torque and muscle force are useful in the estimation of when and how mechanical overload of the musculoskeletal system may lead to disorders. The aim was to study the reliability and validity of magnetic resonance imaging (MRI) to quantify muscle sizes and moment arms by MRI and to test selected anthropometric measures as predictors of muscle sizes and moment arms. A total of 20 healthy Scandinavian women (age 22-58 years) participated in an MRI scanning of their dominant shoulder. With a PC-based program the reliability and the validity of the MRI measurements was estimated to be high, and mean anatomical cross-sectional areas (ACSA) and muscle lengths were measured to be 4.0, 9.8 and 12.1 cm(2) and 12.0, 12.6 and 12.8 cm for m. supraspinatus, m. infraspinatus and m. subscapularis, respectively. Volumes were calculated to be 48.8, 125.1 and 153.6 cm(3). Moment arms were measured with the upper arm in a neutral position and in a functional position of 34 degrees abduction for m. supraspinatus only, and were 2.4 and 2.6 cm. Physiological cross-sectional area (PCSA) and its fiber force component were estimated from dissected fiber length and pennation angle. MRI volume and PCSA were 1.4-1.7 times higher than dissection data, primarily because of age differences. No external anthropometric measures were found to be predictors of volumes or moment arms.

Adult↗
PubMed1999

Discrimination between enantioselective and non-selective binding sites on cellobiohydrolase-based stationary phases by site specific competing ligands.

A systematic study was performed to investigate the influence of cellobiose or lactose on the enantioselective retention behaviour of some beta-blockers in liquid chromatography using Cellobiohydrolase (CHB) I from Trichoderma reesei or Cellobiohydrolase 58 from Phanerochaete chrysosporium immobilized on silica as stationary phases. The results revealed that the retention could be described by the function [equation; see text] where the observed capacity factor corresponds to the sum of an enantioselective mode being influenced by a site specific competing ligand (competitor) and a non-selective mode unaffected by the competitor. A non-constrained non-linear least-square regression gave in all cases virtually identical nondisplacable capacity factors (k'ns) for both enantiomers of the same drug. The experimental capacity factors (k'(x,C)) of the enantiomers all show a close fit to the adapted function. The Kd values calculated for the competitor were also virtually identical for each pair of enantiomers and were in accordance with Ki data determined for the competitors in classical enzyme kinetics experiments, demonstrating that one unique site; namely, the catalytic site, was responsible for the enantioselective binding. Similar results were obtained with the resolution of rac-alprenolol and rac-metoprolol on CBH I phase.

Binding Sites↗
PubMed1999

Linkage analysis of a large Swedish kindred provides further support for a susceptibility locus for schizophrenia on chromosome 6p23.

Several reports have indicated genetic linkage between markers on the short arm of chromosome 6 and schizophrenia. However, significant threshold levels were not always achieved, and the chromosomal regions identified are large and different in different families. One way to decrease the problem of heterogeneity is to study a single extended pedigree. Here we report the analysis of a very large, previously undescribed pedigree from northern Sweden that includes 31 affected individuals. We typed 16 markers spanning 40 cM on the short arm of chromosome 6. Linkage analysis was performed only with the affected individuals. Suggestive lod scores (maximum 2.6) were obtained with markers on chromosome 6p23 in a single branch of the large pedigree indicating possible heterogeneity inside the family. A haplotype comprising markers from D6S309 to D6S1578 was found to segregate with the disease. This chromosomal region is included within a segment proposed to contain a susceptibility gene for schizophrenia by many other investigators. Our results thus give further support for a possible localization of a susceptibility locus for schizophrenia in 6p23 and help to narrow the candidate chromosomal region to the segment included between markers D6S309 and D6S1578.

Alleles↗
PubMed1999

A method to compensate for incomplete 24-hour urine collections in nutritional epidemiology studies.

OBJECTIVE: To develop a method to make use of incomplete 24-hour urinary samples in nutritional epidemiology, especially when validating the dietary intake of nitrogen (protein), sodium and potassium. DESIGN: Urinary data for men and women collected in three different studies were evaluated. The concentration of para-aminobenzoic acid (PABA) in one 24-hour urine sample per person was compared with the concentrations of nitrogen, sodium, potassium and creatinine. SETTING: Men and women living in Cambridge, UK and women living in the town of Varberg, Sweden. SUBJECTS: In total, this study consists of data from 73 Swedish women (20-50 years of age), 165 UK women (50-65 years) and 75 UK men (55-88 years). RESULTS: On average four out of 10 people in this study had a PABA recovery below 85%. The linear regression equations for urinary excretion of nitrogen, sodium and potassium in relation to PABA recovery were y=2.3 + 0.088 x chi (r=0.99), y=45 + 0.82 x chi (r= 0.87) and y = 19 + 0.60 x chi (r= 0.93), respectively. CONCLUSIONS: The linear regression equations can be used for adjusting urinary nitrogen, sodium and potassium in urinary collections in cases where the PABA recovery is below 85%. Since it is common to obtain 24-hour urine collections with a PABA recovery below 85%, this method should increase the usefulness of biological markers of food intake in nutritional epidemiological studies and also increase the possibilities to study people that previously have been part of the drop-out group or the group with low motivation and cooperation. It is important to stress that we have not studied the relationship between PABA recovery and various urinary variables below the PABA recovery of 50%. Thus, in a case of PABA recovery below 50%, we do not recommend the use of this method to compensate for incomplete collections.

4-Aminobenzoic Acid↗
PubMed1999

Fractionation of cellulase and beta-glucosidase in a Trichoderma reesei culture liquid by use of two-phase partitioning.

An aqueous two-phase system based on the two polymers poly(ethylene glycol) and dextran has been used for the fractionation of cellulase enzymes present in culture liquid obtained by fermentation with Trichoderma reesei. The activities of beta-glucosidase and glucanases were separated to high degree by using the two-phase systems for a counter-current distribution process in nine transfer steps. While the glucanases had high affinity to the poly(ethylene glycol) rich top phase the beta-glucosidase was enriched in the dextran-containing bottom phase. Multiple counter-current distribution performed indicates the heterogeneity of beta-glucosidase activities assuming at least four isoenzyme forms. One step concentration of beta-glucosidase by using system with 46:1 phase volume ratio resulted in 16 times higher enzyme activity.

Cellulase↗
PubMed1999

Continuous interscalene brachial plexus block for postoperative analgesia following shoulder surgery.

BACKGROUND: Severe postoperative pain is a well-known problem following shoulder surgery. This study evaluates the clinical efficacy of continuous interscalene brachial plexus block, patient-controlled analgesia, and morphine (i.v. and i.m.) for postoperative analgesia in this setting. METHODS: Thirty patients, scheduled for acromioplasty during general anesthesia, were randomly allocated to one of three different postoperative pain management groups. Group MO received morphine (5 mg i.m. and 2 mg i.v.) when visual analogue pain score (VAS) > 3, group PL received a continuous interscalene brachial plexus block with bupivacaine (1.25 mg kg-1 + 0.25 mg kg-1 h-1) and group PCA received patient-controlled analgesia with morphine (bolus 1 mg). Postoperative pain relief was assessed (24 h) by VAS, circulatory and respiratory stress parameters (heart rate, systemic arterial pressure and respiratory rate) and stress metabolites (glucose, lactate, glycerol by abdominal subcutaneous microdialysis). RESULTS: Pain relief in the PL group was effective (VAS < 3) and significantly more potent than in groups MO and PCA, except at 16 and 20 h. Lactate was significantly increased in the PL group, glucose was significantly increased in all groups, while glycerol showed a variable pattern. There were no significant stress metabolite differences among groups. VAS showed no statistical correlation with microdialysate, respiratory or circulatory data. CONCLUSION: Successful continuous interscalene brachial plexus block provides very good pain relief following shoulder surgery and is superior to the other methods studied. However, we were unable to demonstrate a correlation between VAS pain scores and stress indicators in metabolic, circulatory and respiratory parameters.

Adolescent↗
PubMed1999

Systemic levels and preportal organ release of tissue-type plasminogen activator are enhanced by PEEP in the pig.

BACKGROUND: Endothelium-derived tissue-type plasminogen activator, t-PA, is the key enzyme in the initiation of endogenous thrombolysis. Plasma levels of t-PA increase in response to sympatho-adrenergic activation. In the mesenteric vascular bed an increased norepinephrine spillover has been observed during positive end-expiratory pressure ventilation, PEEP. This experimental study examines the effects of PEEP-induced alterations on regional release rates and systemic levels of t-PA in vivo. METHODS: The protocol included measurements of arterio-venous concentration gradients of t-PA and the respective plasma flow across the pulmonary, coronary, hepatic and preportal vascular beds, in pigs, during zero-PEEP and at 2, 4 and 10 min after the application of a PEEP of 10 cm H2O. Both total plasma t-PA antigen (ELISA with a porcine t-PA standard) and active t-PA (spectrophotometric functional assay) were determined. RESULTS: During zero-PEEP, a high preportal basal net release and hepatic net uptake of total t-PA was observed. With PEEP, the magnitude of the preportal net release of t-PA was markedly enhanced (+24+/-5%), as was hepatic net uptake (+21+/-8%), simultaneously to a significant decrease in liver plasma flow (-30+/-2%). PEEP-induced alterations in active t-PA mirrored those observed in total t-PA. No significant net fluxes of total or active t-PA were observed across the coronary or the pulmonary vascular beds. CONCLUSIONS: Clinically used levels of PEEP induce increases in net release of endothelially derived t-PA within preportal organs. The application of PEEP is associated with increased systemic levels of total and active t-PA, in spite of a simultaneous increase in hepatic net uptake, indicating that the preportal vascular bed can not account for the systemic t-PA response.

Animals↗
PubMed1999

Effects of desflurane on the pig intestinal circulation during hypotension.

BACKGROUND: The aim of the present study was to analyze the perfusion pressure dependency for the splanchnic vascular effects of desflurane (DES). METHODS: We measured portal blood flow (QPORT, perivascular ultrasound) and jejunal mucosal perfusion (JMP; laser Doppler) in pentobarbital-anesthetized pigs (n=10). Experimentally, decreases in mean arterial pressure (MAP) were produced by pericardial infusions of dextran. The protocol included sets of measurements at incremental doses of DES (1, 2, 4 and 6%) prior to and during pericardial infusions. RESULTS: Although QPORT and JMP decreased significantly during pericardial infusions, DES, irrespective of dose, did not reduce QPORT until MAP had decreased below 65-70 mm Hg. In higher MAP ranges, vasodilation in pre-portal tissues was powerful enough to maintain QPORT in spite of concurrent decreases in driving arterial pressure, as produced by either DES or pericardial infusion, or by a combination of both. We found no effects of DES on JMP even at very low MAP (about 40 mm Hg during pericardial infusion), indicating that the normal physiological response of the small intestine to redistribute blood flow from deeper to more superficial layers during hypotension was unimpaired by DES. CONCLUSIONS: Our data suggest a wide dose-tolerability of DES as regards the splanchnic circulation during hypotensive states.

Anesthetics, Inhalation↗
PubMed1999

Endoglucanase 28 (Cel12A), a new Phanerochaete chrysosporium cellulase.

A 28-kDa endoglucanase was isolated from the culture filtrate of Phanerochaete chrysosporium strain K3 and named EG 28. It degrades carboxymethylated cellulose and amorphous cellulose, and to a lesser degree xylan and mannan but not microcrystalline cellulose (Avicel). EG 28 is unusual among cellulases from aerobic fungi, in that it appears to lack a cellulose-binding domain and does not bind to crystalline cellulose. The enzyme is efficient at releasing short fibres from filter paper and mechanical pulp, and acts synergistically with cellobiohydrolases. Its mode of degrading filter paper appears to be different to that of endoglucanase I from Trichoderma reesei. Furthermore, EG 28 releases colour from stained cellulose beads faster than any other enzyme tested. Peptide mapping suggests that it is not a fragment of another known endoglucanases from P. chrysosporium and peptide sequences indicate that it belongs to family 12 of the glycosyl hydrolases. EG 28 is glycosylated. The biological function of the enzyme is discussed, and it is hypothesized that it is homologous to EG III in Trichoderma reesei and the role of the enzyme is to make the cellulose in wood more accessible to other cellulases.

Amino Acid Sequence↗
PubMed1999

Acid hydrolysis of bacterial cellulose reveals different modes of synergistic action between cellobiohydrolase I and endoglucanase I.

Intact and partially acid hydrolyzed cellulose from Acetobacter xylinum were used as model substrates for cellulose hydrolysis by 1,4-beta-D-glucan-cellobiohydrolase I (CBH I) and 1,4-beta-D-endoglucanase I (EG I) from Trichoderma reesei. A high synergy between CBH I and EG I in simultaneous action was observed with intact bacterial cellulose (BC), but this synergistic effect was rapidly reduced by acid pretreatment of the cellulose. Moreover, a distinct synergistic effect was observed upon sequential endo-exo action on BC, but not on bacterial microcrystalline cellulose (BMCC). A mechanism for endo-exo synergism on crystalline cellulose is proposed where the simultaneous action of the enzymes counteract the decrease of activity caused by undesirable changes in the cellulose surface microstructure.

Acetobacter↗
PubMed1999

Diaphragmatic activity after laparoscopic cholecystectomy.

BACKGROUND: Laparoscopic cholecystectomy is presumed to induce a reduction in diaphragmatic activity. Indirect indices of diaphragmatic function based on tidal changes in pressures and cross-section area measurements can be unreliable in the postoperative phase. The present study evaluates diaphragmatic activity by directly recording diaphragmatic EMG (EMGdia) data, along with indirect indices. METHODS: Thirteen adult patients (American Society of Anesthesiologists physical status I or II) undergoing laparoscopic cholecystectomy were examined preoperatively for inspiratory tidal changes in gastric (Pgas-insp) and esophageal (Peso-insp) pressures, and tidal changes in ribcage (Vthor) and abdominal (Vabd) cross-section areas and then again at 1, 6, and 24 h postoperatively combined with EMGdia recordings. Variations in inspiratory gastric (deltaPgas-insp) and inspiratory transdiaphragmatic (deltaPdi-insp) pressures were derived from the above. RESULTS: Laparoscopic cholecystectomy induced a significant reduction in mean deltaPgas-insp, mean deltaPdi-insp, and mean Vabd indicating a reduction of diaphragmatic activity postoperatively. DeltaPdi-insp decreased from 11.8+/-4.0 cm H2O preoperatively to 5.7+/-5.7 cm H2O at 1 h and 6.6+/-5.1 cm H2O at 6 h postoperatively (mean +/- SD; P < 0.05). Vabd decreased from 327.0+/-113.0 ml preoperatively to 174.0+/-65.0 ml at 1 h and 175.0+/-98.0 ml at 6 h postoperatively (mean +/- SD; P < 0.05). These values had partially recovered at 24 h. CONCLUSION: The direct and indirect indices of diaphragmatic activity taken together confirm the presence of reduction in diaphragmatic activity after laparoscopic cholecystectomy followed by its partial recovery at 24 h.

Adult↗
PubMed1998

Progress curves--a mean for functional classification of cellulases.

The chain-end preference and processivity of the cellulases 1,4-beta-D-glucan-cellobiohydrolase I (CBH I) and 1,4-beta-D-glucan-cellobiohydrolase II (CBH II) from Trichoderma reesei and 1,4-beta-D-glucan-cellobiohydrolase 50 (CBH 50) and 1,4-beta-D-glucan-cellobiohydrolase 58 (CBH 58) from Phanerochaete chrysosporium were studied by comparing experimental degradation data on reducing end-labelled bacterial microcrystalline cellulose with computer simulations of different models. Our results with T. reesei and P. chrysosporium cellulases show that there is a common pattern of hydrolysis for CBH-I-type enzymes and another clearly distinguishable pattern for CBH-II-type enzymes, especially in the initial part of the progress curve.

Cellulase↗