Biomedical subjects

B Andersson

Publications and source records attributed to B Andersson.

At least 289 records · Page 16Linked to original sources

PubMed1993

Rapid characterization of HIV-1 sequence diversity using denaturing gradient gel electrophoresis and direct automated DNA sequencing of PCR products.

A direct method for visualization and isolation of sequence variants of human immunodeficiency virus type 1 (HIV-1) utilizing denaturing gradient gel electrophoresis (DGGE) combined with automated direct DNA sequencing was developed. Two fragments from the env gene and one from the nef gene of HIV-1, which together constitute approximately 1.0 kb of sequence, were amplified by PCR and analyzed. HIV-1 variants from each region were resolved and excised from the gel; this was followed by direct sequencing of different viral variants. In 9 infected patients, a limited number of dominant sequence variants could be seen in the three regions, together with a faint background of minor variants. The use of DGGE makes it possible to obtain a direct estimate of overall HIV-1 sequence diversity within patient samples without an intermediate DNA cloning step.

Base Sequence↗

PubMed1993

Antibody response in bronchoalveolar lavage and bile in rats after aerosol immunisation with an Escherichia coli strain producing ovalbumin.

We studied the expression of the antibody response in two parts of the mucosal immune system after exposing rats to an aerosol containing an Escherichia coli O6 strain which carries type 1 fimbriae and which is genetically manipulated to produce ovalbumin (OA). For comparison rats were immunised twice in the Peyer's patches (PP), 3 weeks apart, with the same bacteria. Bile, serum and bronchoalveolar lavage (BAL) were collected from both groups and the levels of antibodies directed against O6 lipopolysaccharide (LPS), type 1 fimbriae and OA were determined. The aerosol-exposed animals all developed higher levels of IgA anti-LPS antibodies in BAL than in bile. IgA antifimbrial antibodies were not detected in BAL despite the presence of such antibodies in the bile. Thus, the ratio BAL:bile was much higher for the anti-LPS antibodies than for the antifimbrial antibodies. This was in contrast to the PP-immunised animals which developed both IgA antifimbrial as well as anti-LPS antibodies in BAL although at a lower level than in bile and the ratios BAL:bile for the antibodies against fimbriae and LPS were similar. IgA anti-OA antibodies were present in bile from both groups but not detected in BAL in any group. IgG anti-LPS antibodies were very high in BAL and in serum in the aerosol-immunised animals, while neither IgG antifimbrial nor anti-OA antibodies were detected. The PP-immunised animals on the other hand developed IgG antibodies against both the fimbrial and the LPS antigens in serum but only against fimbriae in BAL.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗

PubMed1993

Increased interleukin-6 levels in cerebrospinal fluid following subarachnoid hemorrhage.

Serum and cerebrospinal fluid (CSF) samples from 12 patients were analyzed for interleukin (IL)-6, soluble IL-2 receptor (IL-2R), and soluble CD8 levels in order to determine the immune activation profile following subarachnoid hemorrhage (SAH). Dramatically increased levels of IL-6 and moderate increases of soluble IL-2R were detected in the CSF in 11 of the 12 patients; slightly elevated levels of soluble CD8 were observed in six patients. The IL-6 levels were higher on Day 6 than on Days 3 and 9. The increases in IL-6, soluble IL-2R, and soluble CD8 levels in the CSF samples were not paralleled by increased values in the serum samples, and thus probably reflected an intrathecal synthesis of the cytokine. Passive transfer of IL-6 across the blood-brain barrier seemed not to occur since the serum and CSF levels of IL-6 showed a negative correlation. The findings suggest a severe inflammatory affection of the central nervous system that could be of importance in understanding the clinical course in patients following SAH.

Adult↗

PubMed1993

CT-determined changes in adipose tissue distribution during a small weight reduction in obese males.

Nine obese males of Scandinavian origin were examined with a multiscan (n = 22) computerized tomography (CT) technique before and after a small weight reduction (4.4 kg). The total adipose tissue (AT) volume was reduced by 2.6 litres. Expressed as a percentage of initial depot volume, there were significant reductions (P < 0.02) in the AT depots of viscera (9.6%), upper limbs (7.0%), subcutaneous trunk (6.0%) and lower limbs (4.9%), while the AT of head and neck (1.9%) did not decrease significantly (P = 0.08). These results indicated a changed fat patterning and evidence for this was obtained by expressing the AT volume of each depot as a percentage of the total AT volume both before and after the weight reduction. Visceral AT constituted 21.7% of the total AT before and 20.9% after weight reduction. Thus, the fraction of AT in viscera was changed by -0.8 +/- 0.9% units which was significantly different from the change in leg AT (+0.5 +/- 1.1% units) (P < 0.02) and tended to be different from the change of subcutaneous AT (+0.2 +/- 1.0% units) (P < 0.07). Thus, the AT distribution was changed in a favourable direction by weight reduction. Changes in visceral/total AT area ratios of different trunk scans were not consistent and, in a stricter sense, fat patterning cannot be studied with area determinations since AT areas cannot be expressed as fractions of the total AT volume.

Adipose Tissue↗

PubMed1993

Design and surface characteristics of 13 commercially available oral implant systems.

Thirteen commercially available oral implant systems were investigated with respect to design and surface topography. The implants were divided into four groups, depending on their different surface materials and treatments. Surface topography was measured with a measurement system for noncontact surface profilometry using confocal scanning microscopy. Results indicated that design, as well as surface topography, varied considerably between the different implant systems.

Dental Implants↗

PubMed1993

Digital luminescence radiography using a chest phantom. Comparison between radiographs displayed on monitor at a workstation and at a personal.

With the introduction of picture and archiving communicating systems an alternative image display for the wards might be a personal computer (PC). The intention with this study was to evaluate the diagnostic image quality of the monitor of a PC compared to that of a workstation. Eighty-five digital radiographs of a chest phantom with simulated tumors in the mediastinum and right lung were saved on optical discs. The examination were reviewed by 4 radiologists on a monitor at a workstation and at a PC, and receiver operating characteristic (ROC) curves were constructed. No significant difference was found between performance of the PC and the workstation.

Computer Systems↗

PubMed1993

Comparison of powder and aerosolized budesonide in perennial rhinitis: validation of rhinitis quality of life questionnaire.

The aims of the study were to compare the efficacy and side effects of intranasal budesonide as a dry powder and as a freon propelled pressurized aerosol in the treatment of perennial rhinitis and to validate a perennial rhinitis quality of life questionnaire. The design was a single-blind, randomized, parallel group comparison of two active treatments over a 6-week period. Sixty adults with symptomatic perennial rhinitis, stratified for atopy, received 400 micrograms intranasal budesonide administered daily either as one inhalation/nostril/day of pure drug powder or two puffs/nostril/day of drug delivered by a freon propelled aerosol. Subjects kept daily symptom diaries and, at each clinic visit, rhinitis quality of life and adverse experiences were recorded. Fifty-eight subjects completed the study. During the 6 weeks, there were significant improvements in symptoms and quality of life in both treatment groups. The improvements tended to be slightly greater in the aerosol group but the differences did not reach significance. Most frequently reported adverse experiences were headache and nosebleed, which were equally distributed in the two groups. We conclude that budesonide taken 400 micrograms daily for 6 weeks was associated with improvements in perennial rhinitis with little evidence of any difference in efficacy or side effects between the powder and aerosol. The questionnaire is a valid instrument for assessing quality of life in perennial rhinitis clinical trials.

Adult↗

PubMed1992

The single-copy gene psbS codes for a phylogenetically intriguing 22 kDa polypeptide of photosystem II.

Recombinant phages that encode the complete precursor polypeptide for the 22 kDa polypeptide associated with photosystem II have been serologically selected from two lambda gt11 expression libraries made from polyadenylated RNA of spinach seedlings. The cDNAs hybridize to a 1.3 kb RNA species. The precursor protein is comprised of 274 amino acid residues and carries an N-terminal transit peptide of probably 69 amino acid residues. The mature protein exhibits four predicted transmembrane segments and is shown to be an integral component of photosystem II originating in a single-copy gene. The unique characteristics of this protein are: (i) it is the result of a gene-internal duplication of an ancestor with two membrane spans, (ii) a striking resemblance to LHC I/II, CP24/CP29 apoproteins, and ELIPs, although it does not bind chlorophyll and is present in cyanobacteria, and, as these proteins, (iii) it integrates into the membrane with uncleaved routing signals that display remarkable resemblance to patterns found in bipartite transit peptides.

Amino Acid Sequence↗

PubMed1992

6-Hydroxy-3-n-propyl-2,3,4,5-tetrahydro-1H-3-benzazepine and analogs: new centrally acting 5-HT1A receptor agonists.

The ring-closed phenylethylamine analogue 6-hydroxy-3-n-propyl-2,3,4,5-tetrahydro-1H-3-benzazepine (1) is a 5-HT1A receptor agonist of moderate potency, according to both in vivo biochemical data and in vitro binding data. The active compounds of this series also induce the 5-HT behavioral syndrome. Molecular modeling studies were performed with molecular mechanics calculations, and a tentative explanation for the relatively low potency of these serotonergic benzazepines is provided.

Animals↗

PubMed1992

Thermal desorption cold trap-injection in high-resolution gas chromatography: multivariate optimization of experimental conditions.

In studies of low concentrations of volatile compounds in air, the method of adsorption on porous polymers and determination by thermal desorption cold trap-injection high-resolution gas chromatography is finding increasing application. Factors considered important for injection and chromatographic separation of volatile compounds by this method were investigated with the use of multivariate techniques. For the amount injected on to the chromatographic column, the factors of main importance were found to be the temperature of the injection block, the thickness of the internal coating of the cold trap and the flow-rate. Strong interaction effects were noted. For the sharpness of the chromatographic peaks, the flow-rate was the most important factor.

Air Microbiology↗

PubMed1992

On the molecular mechanism of light-induced D1 protein degradation in photosystem II core particles.

The mechanism of D1 protein degradation was investigated during photoinhibitory illumination of isolated photosystem II core preparations. The studies revealed that a proteolytic activity resides within the photosystem II core complex. A relationship between the inhibition of D1 protein degradation and the binding of the highly specific serine protease inhibitor diisopropyl fluorophosphate to isolated complexes of photosystem II was observed, evidence that this protease is of the serine type. Using radiolabeled inhibitor, it was shown that the binding site, representing the active serine of the catalytic site, is located on a 43-kDa polypeptide, probably the chlorophyll a protein CP43. The protease is apparently active in darkness, with the initiation of breakdown being dependent on high light-induced substrate activation. The proteolysis, which has an optimum at pH 7.5, gives rise to primary degradation fragments of 23 and 16 kDa. In addition, D1 protein fragments of 14, 13, and 10 kDa were identified. Experiments with phosphate-labeled D1 protein and sequence-specific antisera showed that the 23- and 16-kDa fragments originate from the N- and C-termini, respectively, suggesting a primary cleavage of the D1 protein at the outer thylakoid surface in the region between transmembrane helices D and E.

Chlorophyll↗

PubMed1992

Two sites of primary degradation of the D1-protein induced by acceptor or donor side photo-inhibition in photosystem II core complexes.

Depending on experimental conditions we have found that photo-inhibitory treatment of photosystem II (PSII) core complexes, isolated from wheat, can generate two fragments of about 23-24 kDa that contain either the C-terminal or N-terminal regions of the D1-protein. A 24 kDa C-terminal fragment appears when the water splitting reaction is not functional and an electron acceptor is present. This 'donor'-side inhibition also generates an N-terminal fragment of about 10 kDa and is suggested to be due to the cleavage of a peptide bond in the region connecting transmembrane segments I and II of the D1-protein. In contrast, an N-terminal 23 kDa D1-protein fragment is detected when the water splitting reactions of the isolated complex are active, and occurs in the absence of an added electron acceptor. This 'acceptor'-side photo-inhibition also generates a C-terminal fragment of about 10 kDa.

Amino Acid Sequence↗

PubMed1992

Reversible and irreversible intermediates during photoinhibition of photosystem II: stable reduced QA species promote chlorophyll triplet formation.

Photoinhibition of photosynthesis was studied in isolated photosystem II membranes by using chlorophyll fluorescence and electron paramagnetic resonance (EPR) spectroscopy combined with protein analysis. Under anaerobic conditions four sequentially intermediate steps in the photoinhibitory process were identified and characterized. These intermediates show high dark chlorophyll fluorescence (Foi) with typical decay kinetics (fast, semistable, stable, and nondecaying). The fast-decaying state has no bound QB but possesses a single reduced QA species with a 30-s decay half-time in the dark (QB, second quinone acceptor; QA, first quinone acceptor). In the semistable state, Q-A is stabilized for 2-3 min, most likely by protonation, and gives rise to the Q-A Fe2+ EPR signal in the dark. In the stable state, QA has become double reduced and is stabilized for 0.5-2 hr by protonation and a protein conformational change. The final, nondecaying state is likely to represent centers where QA H2 has left its binding site. The first three photoinhibitory states are reversible in the dark through reestablishment of QA to QB electron transfer. Significantly, illumination at 4 K of anaerobically photoinhibited centers trapped in all but the fast state gives rise to a spinpolarized triplet EPR signal from chlorophyll P680 (primary electron donor). When oxygen is introduced during anaerobic illumination, the light-inducible chlorophyll triplet is lost concomitant with induction of D1 protein degradation. The results are integrated into a model for the photoinhibitory process involving initial loss of bound QB followed by stable reduction and subsequent loss of QA facilitating chlorophyll P680 triplet formation. This in turn mediates light-induced formation of highly reactive and damaging singlet oxygen.

Journal Article↗

PubMed1992

Mutations causing defective splicing in the human hprt gene.

Ten intron mutations and one exon mutation giving rise to defective splicing in the human gene for hypoxanthine phosphoribosyl transferase (hprt) in T-lymphocytes have been characterized. The splicing mutants were detected by PCR amplification of hprt cDNA and direct sequencing. Nine of the mutants showed skipping of whole exons or parts of exons in the cDNA, one mutant had an inclusion of an intron sequence into the cDNA, and one mutant showed both inclusion of an intron sequence and skipping of exons as well as a normal cDNA. Genomic PCR and direct sequencing of the splice sites involved showed one deletion of three base pairs and 10 different single base alterations to be responsible for these splice alterations. One mutation in the last base pair of exon 6 causing skipping of the entire exon 6 was found, whereas an identical mutation in the last base pair of exon 2 caused no aberrant splicing. It was also found that a deletion mutation in the pyrimidine rich stretch of the acceptor site of intron 7 caused skipping of the entire exon 8, whereas a base substitution in the last base of intron 7 caused exclusion of only the first 21 base pairs of exon 8 as a result of the activation of a cryptic acceptor site in exon 8. The results show that many different types of mutations at several different sites can cause splicing errors in the hprt gene and that the sequence differences between the splice sites influence the possible spectrum of mutations in each site.

Base Sequence↗

PubMed1992

Mutation analysis and prenatal diagnosis in a Lesch-Nyhan family showing non-random X-inactivation interfering with carrier detection tests.

A nonsense mutation at the CpG-site in the codon for Arg(169) in the gene for hypoxanthine phosphoribosyltransferase (hprt) was identified by genomic polymerase chain reaction (PCR) and DNA sequencing in cultured fibroblasts from two brothers with Lesch Nyhan's syndrome. The recurrence of mutation at this CpG-site in several unrelated Lesch-Nyhan families suggests that deamination of 5-methylcytosine is a possible mechanism for mutagenesis. The level of hprt-mRNA in the fibroblasts of the patients was similar to that in healthy controls, whereas hprt-enzyme activity was not detectable. The mutation in this family was also identified in five female relatives and prenatally in a male fetus. Unexpectedly, results from hair follicle analyses and fibroblast selection studies in 8-azaguanine and 6-thioguanine medium showed a non-carrier phenotype in three of the female heterozygotes, whereas X-inactivation mosaicism was demonstrated in one heterozygote. A possible explanation for the apparent non-random X-inactivation in this family is the co-existence of the hprt mutation with an undefined X-linked lethal mutation. This observation is of practical relevance for carrier detection in other Lesch-Nyhan families.

Base Sequence↗

PubMed1992

Demonstration of digital radiographs by means of ink jet-printed paper copies: pilot study.

Different digital medical images have been printed on paper with a continuous ink jet printer, and the quality has been evaluated. The emphasis has been on digital chest radiographs from a computed radiography system. The ink jet printing technique is described as well as the handling of the image data from image source to printer. Different versions of paper prints and viewing conditions were compared to find the optimum alternative. The evaluation has been performed to maximize the quality of the paper images to make them conform with the corresponding film prints and monitor images as much as possible. The continuous ink jet technique offers high-quality prints on paper at a considerably lower cost per copy compared with the cost of a film print. With a future switch-over from diagnosing of digital images on film to diagnosing them on monitors, hard copies for demonstration purposes will occasionally be needed. This need can be filled by ink jet-printed paper copies.

Copying Processes↗

PubMed1992

Ultrastructural and biochemical characterization of a Synechocystis 6803 mutant with inactivated psbA genes.

A constructed Synechocystis 6803 mutant with a deletion of the three psbA genes was subjected to ultrastructural and biochemical characterization. This D1-depleted mutant also lacks the D2 protein and the chlorophyll a-binding protein CP-47. A general ultrastructural comparison between the wild type and the mutant did not reveal any major changes in cell appearance. We found by freeze-fracture analysis that approximately 60% of the endoplasmic face particles found in the wild-type thylakoids were missing in the mutant. A corresponding increase in protoplasmic face particles in the mutant thylakoids may represent a subcomplex of those photosystem II (PS II) polypeptides which accumulate in the absence of the D1 protein. Correlation of the PS I:PS II ratio with freeze-fracture data indicates that there is only one reaction center in each PS II freeze-fracture particle. Fluorescence measurements show that the CP-43 polypeptide in the mutant binds chlorophyll and that it may be connected to the phycobilisomes. Excitation energy can be transferred from the phycobilisomes to photosystem I in the absence of the photosystem II reaction center heterodimer and CP-47. This suggests that exciton transfer to photosystem I is mediated either directly by a terminal phycobilisome transmitter or via CP-43.

Bacterial Proteins↗

PubMed1992

The morphology and metabolism of intraabdominal adipose tissue in men.

Mass, morphology, and metabolism of total adipose tissue and its subcutaneous, visceral, and retroperitoneal subcompartments were examined in 16 men with a wide variation of total body fat. Computerized tomography (CT) scans showed that the intraabdominal fat mass comprised approximately 20% of total fat mass. Visceral and retroperitoneal fat masses were approximately 80% and 20% of total intraabdominal fat mass, respectively. Enlargement of intraabdominal fat depots was due to a parallel adipocyte enlargement only. Direct significant correlations were found between these adipose tissue masses and blood glucose and plasma insulin levels, blood pressure, and liver function tests, while glucose disposal rate during euglycemic glucose clamp measurements at submaximal insulin concentrations (GDR), plasma testosterone, and sex hormone-binding globulin concentrations correlated negatively. The correlations for glucose, insulin, and GDR were strongest with visceral fat mass. Adipose tissue lipid uptake, measured after oral administration of labeled oleic acid in triglyceride, was approximately 50% higher in omental than in subcutaneous adipose tissues. Adipocytes from omental fat also showed a higher lipolytic sensitivity and responsiveness to catecholamines. Furthermore, these adipocytes were less sensitive to the antilipolytic effects of insulin. Both lipid uptake and lipolytic sensitivity and responsiveness showed strong correlations (r = 0.8 to 0.9) to blood glucose and plasma insulin concentrations and also to the GDR (negative), while no such correlations were found with lipid uptake in subcutaneous or retroperitoneal abdominal adipose tissues. Taken together, these results suggest a higher turnover of lipids in visceral than in the other fat depots, which is closely correlated to systemic insulin resistance and glucose metabolism in men.

Abdomen↗