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Biomedical subjects

J Johansson

Publications and source records attributed to J Johansson.

At least 109 records · Page 6Linked to original sources
PubMed1998

Fluorescence imaging of light absorption for axial-beam geometry in capillary electrophoresis.

A new method for investigation of axial-beam absorption detection for improved detection limits in microcolumn separations is reported. The method is based on fluorescence imaging of light absorption along a separation capillary. The probing UV light is introduced at one end of the capillary and shows an exponential fall-off along the capillary. As the UV light propagates through the sample peaks, an additional loss in intensity will be observed. In order to view the absorption profile along the capillary, a background fluorophore is added to the buffer. A charge-coupled device (CCD) detector and imaging optics are placed beside the capillary to view the capillary in a direction perpendicular to the capillary. Signal integration is employed for consecutive exposures as well as for neighboring detector pixels in order to increase the signal-to-noise ratio. Measurements for stilbene 3 with sulforhodamine B as a background fluorophore are presented. The characteristics of the detection method and potential improvements are discussed.

Electrophoresis, Capillary↗
PubMed1998

Pulmonary surfactant-associated polypeptide C in a mixed organic solvent transforms from a monomeric alpha-helical state into insoluble beta-sheet aggregates.

In the 35-residue pulmonary surfactant-associated lipopolypeptide C (SP-C), the stability of the valyl-rich alpha-helix comprising residues 9-34 has been monitored by circular dichroism, nuclear magnetic resonance, and Fourier transform infrared spectroscopy in both a mixed organic solvent and in phospholipid micelles. The alpha-helical form of SP-C observed in freshly prepared solutions in a mixed solvent of CHCl3/CH3OH/0.1 M HCl 32:64:5 (v/v/v) at 10 degrees C undergoes within a few days an irreversible transformation to an insoluble aggregate that contains beta-sheet secondary structure. Hydrogen exchange experiments revealed that this conformational transition proceeds through a transition state with an Eyring free activation enthalpy of about 100 kJ mol(-1), in which the polypeptide segment 9-27 largely retains a helical conformation. In dodecylphosphocholine micelles, the helical form of SP-C was maintained after seven weeks at 50 degrees C. The alpha-helical form of SP-C thus seems to be the thermodynamically most stable state in this micellar environment, whereas its presence in freshly prepared samples in the aforementioned mixed solvent is due to a high kinetic barrier for unfolding. These observations support a previously proposed pathway for in vivo synthesis of SP-C through proteolytic processing from a 21-kDa precursor protein.

Amino Acid Sequence↗
PubMed1998

The innervation of the synovium of the knee joint in the guinea pig: an immunohistochemical and ultrastructural study.

The innervation of the knee joint synovial membrane of the guinea pig, i.e., the synoviocyte layer, the subjacent connective tissue and the connective tissue region beneath, was analyzed with immunohistofluorescence and electron microscopy. A screening of the innervation with antibodies against the general axon marker -- protein gene product (PGP) 9,5 -- revealed the presence of nerve fibers distributed in various regions of the knee joint synovial membrane. Confirming previous studies, some of these nerve fibers stained with antibodies to tyrosine hydroxylase (TH), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP), and vasoactive intestinal polypeptide (VIP). In addition, dynorphin (DYN)-containing fibers were detected, which have not been reported previously in normal joints. In general, the immunoreactive fibers were observed close to the synoviocytes and at blood vessels. Fibers with colocalization of NPY- and TH-like immunoreactivities (LIs), as well as of DYN- and TH-LIs were demonstrated. In the electron microscope, bundles of unmyelinated fibers as well as single fibers were found in the connective tissue region below the synoviocytes. Varicose parts of the nerve fibers contained mainly small, clear vesicles. Small and large dense-cored vesicles were also seen, but less frequently. Denser portions of the plasma membranes of some axons were observed in these regions, facing the extracellular space. Myelinated fibers were also observed in some nerve bundles. These findings emphasize the complex innervation of the synovial membrane, with nerve fibers containing a host of neuroactive substances. Altogether, these fibers are probably involved in many functions such as vasoregulation and control of synovial secretion in addition to being a source of mediators in joint inflammation.

Animals↗
PubMed1998

Successful thrombolysis of an occluded modified Blalock shunt three days after operation.

A 10-day-old boy with pulmonary atresia received a right-sided aortopulmonary polytetrafluoroethylene shunt. Three days after the operation he became cyanotic and was reintubated. Shunt occlusion was confirmed with angiography. Recombinant tissue plasminogen activator was given locally into the proximal end of the shunt. The thrombus was completely resolved after 2 days. When administration of recombinant tissue plasminogen activator was stopped, heparin infusion was started for 5 days. Shunt patency was demonstrated by angiography at 3 months postoperatively.

Anastomosis, Surgical↗
PubMed1998

Active or passive chest drainage after oesophagectomy in 101 patients: a prospective randomized study.

BACKGROUND: This study evaluates the efficiency and safety of two methods of chest drainage after uncomplicated oesophagectomy. METHODS: A prospective randomized study between active suction drainage and passive chest drainage was carried out in 101 patients who underwent gastric pull-up oesophagectomy. RESULTS: No difference in the prevalence of pneumothorax during treatment was noted between the active (nine of 55) and the passive (four of 46) drainage groups (P=0.20). Nor was there any difference in the size (P=0.46) and duration (P=0.53) of the pneumothorax. There was no significant difference in right (P=0.84) and left (P=0.61) basal atelectases and the amounts of right (P=0.10) and left (P=0.24) pleural effusions. There were significantly more basal atelectases (P < 0.001) and pleural effusions (P<0.001) in the non-operated left side compared with the operated right side. Postoperative hospital stay was the same in both groups (median 13 days; P=0.86). The hospital mortality rate was two of 101, and was not affected by the type of drainage. CONCLUSION: Passive drainage did not reduce hospital stay, but was as safe and effective as the active system in draining the pleural cavity after uncomplicated oesophagectomy.

Anastomosis, Surgical↗
PubMed1998

Expanded CAG repeats in Swedish spinocerebellar ataxia type 7 (SCA7) patients: effect of CAG repeat length on the clinical manifestation.

Spinocerebellar ataxia 7 (SCA7) is a neurodegenerative disorder characterized by degeneration of the cerebellum, brainstem and retina. The gene responsible for SCA7, located on chromosome 3p, recently was cloned and shown to contain a CAG repeat in the coding region of the gene, that is expanded in SCA7 patients of French origin. We examined the SCA7 repeat region in four Swedish SCA7 families as well as in 57 healthy controls. All Swedish SCA7 patients exhibited expanded CAG repeats with a strong negative correlation between repeat size and age of onset. The repeat length in SCA7 patients ranged from 40 to >200 repeats. The largest expansion was observed in a juvenile case with an age of onset of 3 months, and represents the longest polyglutamine stretch ever reported. In patients with 59 repeats or more, visual impairment was the most common initial symptom observed, while ataxia predominates in patients with <59 repeats. Two of the Swedish SCA7 families analysed in this study were shown to be related genealogically. The other two SCA7 families could not be traced back to a common ancestor. All four families shared the same allele on the disease chromosome at a locus closely linked to SCA7, suggesting the possibility of a founder effect in the Swedish population.

Adolescent↗
PubMed1998

Explosive rise of serum CA 125 following the rupture of ovarian endometrioma.

Serum CA 125 concentration is seldom >100 IU/ml in endometriosis. We report a patient with ruptured endometrioma presenting with a very high CA 125 concentration, 9300 IU/ml. Elimination of endometriosis was followed by a sharp decrease in serum CA 125. We conclude that some of the CA 125 molecules from the ruptured endometriotic cyst may be transferred through the peritoneum, thereby increasing serum CA 125 concentration. The associated inflammatory reaction of the mesothelial cells of the peritoneum was probably the most important contributor to this phenomenon, as mesothelial cells are an important source of CA 125.

Endometriosis↗
PubMed1998

H-NS and StpA proteins stimulate expression of the maltose regulon in Escherichia coli.

The nucleoid-associated protein H-NS is a major component of the chromosome-protein complex, and it is known to influence the regulation of many genes in Escherichia coli. Its role in gene regulation is manifested by the increased expression of several gene products in hns mutant strains. Here we report findings showing that H-NS and the largely homologous protein StpA play a positive role in the expression of genes in the maltose regulon. In studies with hns mutant strains and derivatives also deficient in the stpA gene, we found that expression of the LamB porin was decreased. Our results showed that the amounts of both LamB protein and lamB mRNA were greatly reduced in hns and hns-stpA mutant strains. The same results were obtained when we monitored the amount of transcription from the malEFG operon. The lamB gene is situated in the malKlamBmalM operon, which forms a divergent operon complex together with the malEFG operon. The activation of these genes depends on the action of the maltose regulon activator MalT and the global activator cyclic AMP receptor protein. Using a malT-lacZ translational fusion and antiserum raised against MalT to measure the expression of MalT, we detected reduced MalT expression in hns and hns-stpA mutant strains in comparison with the wild-type strain. Our results suggest that the H-NS and StpA proteins stimulate MalT translation and hence play a positive role in the control of the maltose regulon.

ATP-Binding Cassette Transporters↗
PubMed1998

Synthetic surfactant protein analogues.

Surfactant preparations for the treatment of respiratory distress syndrome (RDS) that contain phospholipids and small amounts of the two hydrophobic proteins, SP-B and SP-C, are presently obtained from animal lungs. Since structural information about SP-B and SP-C is available, it appears possible to design analogues that can replace the native proteins in synthetic surfactants. SP-C contains a single helix, but analogues with the poly-Val sequence of the native molecule do not fold into a native-like alpha-helical conformation. However, replacement of all Val with Leu yields efficient folding into a helical structure and Leu-based SP-C analogues effectively accelerate spreading of surfactant lipids and exhibit some physiological activity in animal models of RDS. The inferior in vivo activity of synthetic surfactants containing SP-C only compared to that of surfactant preparations derived from natural sources may be caused by a lack of covalently linked palmitoyl groups in the analogues and/or absence of SP-B. SP-B is significantly larger than SP-C and has a tertiary fold of several amphipathic helices in a dimeric structure. A single simplified amphipathic helical peptide containing only Leu and Lys does not mimic the surface properties of SP-B in vitro. These circumstances make the design of SP-B analogues from solely structural considerations less likely to be successful than in the case of SP-C.

Drug Design↗
PubMed1998

The ability of non-invasive physiological tests to detect arterial occlusions in the lower extremity. An ROC study with particular regard to recruitment of patients for clinical trials.

In the prerandomization phase of a clinical trial it is essential to be able to exclude, in a non-invasive way, patients who cannot be randomized into the trial. The ability of routine non-invasive physiological examinations to detect arterial occlusion in the lower extremities was investigated in 182 patients with hypercholesterolaemia. Ankle blood pressure measurement, pulse oscillometry, digital pulse plethysmography and treadmill and cycle exercise tests were performed as part of the prerandomization phase of the Probucol Quantitative Regression Swedish Trial (PQRST). The PQRST was designed to compare the antiatherosclerotic effect of two different lipid-lowering regimens. Before randomization the patients also underwent aorto-femoral arteriography, which was used as 'gold standard'. The results were analysed with ROC methodology. Ankle blood pressure measurement (ABP) and inclination time (IT), measured with digital pulse plethysmography, without significant mutual difference, were the variables, best able to detect occlusions. For ABP, the AZ-values were 0.85, 0.82 and 0.94 in detection of right-sided, left-sided and bilateral occlusion, respectively. The corresponding figures for IT were AZ = 0.86, 0.91 and 0.93. If a bilateral occlusion was predicted in a patient with an ABP value of < = or 0.98, a specificity of 0.90 and a sensitivity of 0.87 were obtained, using arteriography as reference method. For IT, with a critical value of 320 ms, sensitivity and specificity were 0.83 and 0.90, respectively.

Adult↗
PubMed1998

Heart rate variability is related to leucocyte count in men and to blood lipoproteins in women in a healthy population of 35-year-old subjects.

OBJECTIVES: To investigate if, in a healthy randomly-selected population of 35-year-old men and women, there already is a relation between decreased heart rate variability and conventional risk factors for cardiovascular disease. BACKGROUND: Analysis of heart rate variability (HRV) has been used for estimating tonic autonomic activity. HRV is reduced in patients with various cardiovascular diseases. If a decreased HRV is a late phenomenon in the progression of cardiovascular disease, or if it parallels or even precedes manifest disease is unknown. DESIGN: Spectral analysis of HRV was made from 24-hour ambulatory electrocardiograms in a randomised population of healthy 35-year-old men (n = 63) and women (n = 70). The different spectral indices of HRV were analysed against gender, leucocyte count (previously described as an independent risk factor for cardiovascular disease), blood lipoproteins, smoking, heredity, body mass index (BMI) and systolic blood pressure. SETTING: A research centre of general medicine and a university hospital. RESULTS: Mean heart rate was lower, total power (TP), very low frequency power (VLF) and low frequency power (LF) were higher in men than in women. In women TP, VLF and LF were negatively correlated to BMI, smoking, triglycerides and positively correlated to HDL cholesterol. TP and VLF were also negatively correlated to risk factor score. High frequency power (HF), a marker of parasympathetic activity, was positively related to HDL cholesterol. In men, at daytime, TP, VLF, LF and HF were negatively correlated to leucocyte count. TP, VLF and LF were also negatively correlated to triglycerides and VLF also to risk factor score. CONCLUSIONS: There are correlations between HRV and known risk factors for cardiovascular disease already in a healthy 35-year-old population. A novel observation is the relationship in men between leucocyte count and heart rate variability.

Adult↗
PubMed1997

Reverse-phase HPLC of the hydrophobic pulmonary surfactant proteins: detection of a surfactant protein C isoform containing Nepsilon-palmitoyl-lysine.

A reverse-phase HPLC protocol for analysis of strictly hydrophobic peptides and proteins was developed. Peptide aggregation is minimized by using only 25-40% water in methanol or ethanol as initial solvents and subsequent elution with a gradient of propan-2-ol. Analysis of the pulmonary surfactant-associated proteins B (SP-B) and C (SP-C) with this method reveals several features. (1) SP-B and SP-C retain their secondary structures and separate by about 15 min over a 40 min gradient. SP-B is more hydrophilic than SP-C, which in turn behaves chromatographically like palmitoyl-ethyl ester. (2) SP-C exhibits isoforms additional to the major form characterized previously, which contains two thioester-linked palmitoyl groups. The isoforms now observed contain one or three palmitoyl moieties and constitute together 15-20% of the major form. The tripalmitoylated species contains a palmitoyl group linked to the epsilon-amino group of Lys-11, as concluded from the elution position,MS and amino acid sequence analysis. The tripalmitoylated form increases relative to the dipalmitoylated form on incubation of SP-C ina phospholipid environment. An Nepsilon-bound palmitoyl moiety constitutes a third mode of fatty acyl modification of proteins, in addition to the established Nalpha-bound myristoyl groups and S-bound palmitoyl chains. (3) The dimeric structure of SP-B, lacking covalent modifications, is confirmed by MS detection of the dimer. No SP-B isoforms were detected. (4) Denatured, non-helical SP-C can be distinguished chromatographically from the native alpha-helical peptide. (5) HPLC of SP-C at 60-75 degrees C reveals an isoform containing an extra 14 Da moiety compared with the main form. This is concluded to arise from inadvertent methyl esterification of the C-terminal carboxy group. In conclusion, this HPLC method affords a sensitive means of assessing modifications and conformations of SP-B or SP-C in different disease states and before functional studies. It might also prove useful for analysis of other strictly hydrophobic polypeptides.

Animals↗
PubMed1997

Molecular structures and interactions of pulmonary surfactant components.

The dominating functional property of pulmonary surfactant is to reduce the surface tension at the alveolar air/liquid interface, and thereby prevent the lungs from collapsing at the end of expiration. In addition, the system exhibits host-defense properties. Insufficient amounts of pulmonary surfactant in premature infants causes respiratory distress syndrome, a serious threat which nowadays can be effectively treated by airway instillation of surfactant preparations. Surfactant is a mixture of many molecular species, mainly phospholipids and specific proteins, surfactant protein A (SP-A), SP-B, SP-C and SP-D. SP-A and SP-D are water-soluble and belong to the collectins, a family of large multimeric proteins which structurally exhibit collagenous/lectin hybrid properties and functionally are Ca2+-dependent carbohydrate binding proteins involved in innate host-defence functions. SP-A and SP-D also bind lipids and SP-A is involved in organization of alveolar surfactant phospholipids. SP-B belongs to another family of proteins, which includes also lipid-interacting polypeptides with antibacterial and lytic properties. SP-B is a 17.4-kDa homodimer and each subunit contains three intrachain disulphides and has been proposed to contain four amphipathic helices oriented pairwise in an antiparallel fashion. SP-A, SP-B and SP-D all have been detected also in the gastrointestinal tract. SP-C, in contrast, appears to be a unique protein with extreme structural and stability properties and to exist exclusively in the lungs. SP-C is a lipopeptide containing covalently linked palmitoyl chains and is folded into a 3.7-nm alpha-helix with a central 2.3-nm all-aliphatic part, making it perfectly suited to interact in a transmembranous way with a fluid bilayer composed of dipalmitoylglycerophosphocholine, the main component of surfactant. Homozygous genetic deficiency of proSP-B causes lethal respiratory distress soon after birth and is associated with aberrant processing of the precursor of SP-C. This review focuses on the chemical composition, structures and interactions of the pulmonary surfactant, in particular the associated proteins.

Animals↗
PubMed1997

Laser-induced fluorescence studies of normal and malignant tumour tissue of rat following intravenous injection of delta-amino levulinic acid.

BACKGROUND AND OBJECTIVE: Laser-induced fluorescence was studied in normal and tumour tissue of rat after intravenous injection of delta-amino levulinic acid (ALA). The aim of the study was to investigate the protoporphyrin IX accumulation in different tissue types in rat after systemically administered ALA. STUDY DESIGN/MATERIAL AND METHODS: A malignant rat tumour and normal tissue from 13 different organs were investigated in eight rats. The rats were injected with two different ALA doses, 30 and 90 mg/kg b.w., and the investigations were performed at 10, 30 and 240 min after the injection. The fluorescence was recorded utilising an optical fibre based fluorosensor at 405 nm excitation. RESULTS: Fluorescence spectra were recorded in the 400-750 nm wavelength region including the dual-peaked PpIX fluorescence at about 635 and 705 nm, and the tissue autofluorescence peaking at about 500 nm. The maximum tumour build-up of PpIX was achieved already in less than 1 hr after ALA injection. The fluorescence demarcation between tumour and surrounding tissue was a factor of 7-8:1 after 30 min and decreased for longer retention times. The accumulation in 13 different organs was investigated and a particularly high PpIX build-up was found in stomach and intestine. CONCLUSIONS: Fluorescence detection following i.v. injection of ALA provides attractive diagnostics for the experimental tumour used, indicating clinical usefulness.

Aminolevulinic Acid↗