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Biomedical subjects

A Petersen

Publications and source records attributed to A Petersen.

At least 109 records · Page 6Linked to original sources
PubMed1992

[Strategy for delivery in breech presentations. A retrospective study].

A six-year material of 236 singleton breech deliveries at term was evaluated retrospectively. Infants who were small for the gestational ages at birth were excluded. Vaginal delivery proved successful in 41.1% of the material. The vaginal success rate was 61.8. Low parity and age and high birth weight reduced the vaginal success rate. The route of delivery did not affect the outcome in terms of infantile morbidity or mortality. Nevertheless, an increased number of neonates with congenital disorders was observed. It is concluded that trial of vaginal delivery may be employed in a selected group of pregnant women with breech presentations without increasing the risk of adverse effects of the neonate.

Adult↗
PubMed1992

Epitope analysis of the allergen ovalbumin (Gal d II) with monoclonal antibodies and patients' IgE.

Ovalbumin (OVA) is a major allergen (Gal d II) of hen egg white and is often the cause of hypersensitivity reactions to food. Further knowledge of the antigenic and allergenic epitopes of allergens will provide better treatment of this disease. To analyse these epitopes we produced a panel of monoclonal antibodies (mAbs) against native OVA. The initial information about the epitopes was obtained with the binding patterns of these mAbs in IEF-immunoprints and western blots of OVA under reducing and non-reducing conditions. It was possible to demonstrate that the different conformations of OVA exhibit different epitopes, and that there are other epitopes which are shared by each conformation. Seven different, although sometimes overlapping epitopes, could be determined on native OVA; four different epitopes on denaturated non-reduced OVA by means of immunoblots of the intact molecule. The number of epitopes which could be differentiated by the mAbs was increased by the use of peptide blots after CNBr fragmentation of the molecule. IgE binding to different OVA conformations and to CNBr-fragments of OVA was also detectable and appears in the same regions as the reactivity of some mAbs. Western blots of OVA and CNBr-peptides demonstrate that some antigenic/allergenic binding sites seem at least partly to be continuous epitopes. The identification of the CNBr-fragments was performed by a microsequence analysis of blotted CNBr-fragments after a 2-dimensional electrophoresis. IgE was found to bind the two largest CNBr-fragments (residues 41-172 and 301-385), but not the fragment corresponding to residues 173-196. A number of monoclonal antibodies also reacted with the two large fragments, especially with fragment 301-385, and some bind also to shorter peptides, such as fragment 173-196, which were not reactive to patients' IgE. Most of the monoclonal antibodies and patients' IgE bind to the fragments 41-172 and 301-385 in 2D-PAGE blots suggesting that these fragments are involved in an immunogenic structure.

Amino Acid Sequence↗
PubMed1992

Characterization of isoforms of the major allergen Phl p V by two-dimensional immunoblotting and microsequencing.

Timothy pollen extract was separated by 2D PAGE blot for further characterization of the major allergen Phl p V. Using pooled patient serum, we demonstrated that Phl p V consists of 4 components at 32 kD and 4 components at 38 kD, each differing in their pIs. The primary structure and the amino acid composition of the 8 proteins were determined form the blotted samples. Proteins of the same molecular weight did not differ in the 20 N-terminal amino acid residues, whereas the 32- and 38-kD proteins showed only 60% sequence identity. Furthermore, the results of the amino acid analyses suggest differences in their protein structure. Therefore, it might be possible that both proteins express different IgE-reactive epitopes.

Allergens↗
PubMed1992

Essential fructosuria: increased levels of fructose 3-phosphate in erythrocytes.

Erythrocytes of 3 adult siblings with essential fructosuria contained 45-200 mumol/l fructose 3-phosphate (Fru-3-P), i.e. 3-15 times the concentration in normal controls. Sorbitol 3-phosphate was also increased, but to a lesser degree. An oral load with 50 g of fructose produced an additional 40 mumol/l increase of erythrocyte Fru-3-P after 5 h. The rate of Fru-3-P formation by red cells in vitro was normal. HbA1 and HbA1c were normal. The suspected pathogenetic role of Fru-3-P in diabetic complications is questioned.

Adult↗
PubMed1991

Lung transplantation in the rat. A morphometric analysis of the gas exchange region.

Single-lung transplantation in the rat provides a model that allows investigators to study immunologic, cellular, and morphologic changes associated with allograft rejection. We performed morphometric analysis of transplanted and nontransplanted lungs removed from recipients having received isografts, allografts, or hilus-stripping up to six months previously, and having received cyclosporine on the first postoperative day, the second postoperative day, the first five days, or not at all. When CsA was not administered, there was extensive and rapid destruction of the alveolar septa with consolidation and rejection of the transplanted lung within one week. In contrast, the allografts from rats treated with CsA were not obviously changed compared with the control lung. To evaluate whether or not these CsA-treated allografts had even subtle injury to alveolar septal cells, a morphometric analysis using transmission electron microscopy was used. There were no significant changes between control (nontransplanted or hilus-stripped) lungs and isografted or allografted lungs for most parameters measured. Exceptions included type I epithelial cell volume, which increased in rats treated with CsA on postoperative day 1 only, and the tissue component of diffusing capacity, which decreased in rats treated with CsA on postoperative day 2 only. We conclude that CsA treatment of rats given lung allografts effectively blocks the development of injury in the gas exchange region. The effect is achieved when the CsA is given during the first five days following transplantation in rats, and may be influenced by the timetable of administration and cumulative dosage.

Animals↗
PubMed1991

Epitope mapping of allergens and antigens of timothy pollen extract.

For the identification of allergens in crude timothy pollen extract, 2D immunoblotting was performed with subsequent use of patients' IgE. Only about 15 of more than 70 detectable components with molecular weights of 55, 38, 35, and 32 kD showed IgE-reactivity. The 55 and 35 kD allergens were identified as glycoproteins by a glycan detection kit. To investigate the protein structure of the allergens, proteins of the pollen extract were cleaved by CNBr and endoproteinases. The cleavage products were identified by patients' IgE and monoclonal antibodies (moab) raised against timothy pollen proteins. While the use of endoproteinases resulted in a complete loss of some allergens, CNBr produced smaller IgE-reactive proteins, e.g. the 38 kD component was split into a 32 kD component and the original 32 kD protein was partially cleaved into IgE-reactive fragments of 30, 21, and 15 kD. In order to investigate the IgE-binding epitopes we intend to determine the amino acid sequence of the cleavage products.

Allergens↗
PubMed1990

Identification of sorbitol 3-phosphate and fructose 3-phosphate in normal and diabetic human erythrocytes.

Using 31P NMR spectroscopy, we have identified sorbitol 3-phosphate and fructose 3-phosphate in normal human erythrocytes wherein their concentrations are estimated to be 13 mumol/liter cells. Incubation of hemolysates with sorbitol, fructose and ATP suggest that both sorbitol and fructose are phosphorylated separately and directly at the 3-hydroxyl position suggesting the presence in these cells of a novel and specific kinase(s). In addition to sorbitol 3-phosphate and fructose 3-phosphate which were previously identified in the mammalian lens and sciatic nerve, erythrocytes have two extra metabolites resonating at 6.7 and 6.8 ppm in the 31P NMR spectrum. Although not identified in this study, the unusual chemical shifts of these compounds, their low pKa values and the fact that they appear as doublet in proton-coupled 31P NMR spectra, suggest that these phosphomonoesters belong to the same class of metabolites as sorbitol 3-phosphate and fructose 3-phosphate. Preliminary studies of erythrocytes from an unselected group of diabetic subjects showed an overall increase in the concentration of all four metabolites, although an overlap with normal values was noted.

Adult↗
PubMed1990

31P-NMR measurements of ATP, ADP, 2,3-diphosphoglycerate and Mg2+ in human erythrocytes.

Absolute 31P-NMR measurements of ATP, ADP and 2,3-diphosphoglycerate (2,3-DPG) in oxygenated and partly deoxygenated human erythrocytes, compared to measurements by standard assays after acid extraction, show that ATP is only 65% NMR visible, ADP measured by NMR is unexpectedly 400% higher than the enzymatic measurement and 2,3-DPG is fully NMR visible, regardless of the degree of oxygenation. These results show that binding to hemoglobin is unlikely to cause the decreased visibility of ATP in human erythrocytes as deoxyhemoglobin binds the phosphorylated metabolites more tightly than oxyhemoglobin. The high ADP visibility is unexplained. The levels of free Mg2+ [( Mg2+]free) in human erythrocytes are 225 mumol/l at an oxygen saturation of 98.6% and instead of the expected increase, the level decreased to 196 mumol/l at an oxygen saturation of 38.1% based on the separation between the alpha- and beta-ATP peaks. [Mg2+]free in the erythrocytes decreased to 104 mumol/l at a high 2,3-DPG concentration of 25.4 mmol/l red blood cells (RBC) and a normal ATP concentration of 2.05 mmol/l RBC. By increasing the ATP concentration to 3.57 mmol/l RBC, and with a high 2,3-DPG concentration of 24.7 mmol/l RBC, the 31P-NMR measured [Mg2+]free decreased to 61 mumol/l. These results indicate, that the 31P-NMR determined [Mg2+]free in human erythrocytes, based solely on the separation of the alpha- and beta-ATP peaks, does not give a true measure of intracellular free Mg2+ changes with different oxygen saturation levels. Furthermore the measurement is influenced by the concentration of the Mg2+ binding metabolites ATP and 2,3-DPG. Failure to take these factors into account when interpreting 31P-NMR data from human erythrocytes may explain some discrepancies in the literature regarding [Mg2+]free.

2,3-Diphosphoglycerate↗
PubMed1990

Inosine/pyruvate/phosphate medium but not adenosine/pyruvate/phosphate medium introduces millimolar amounts of 5-phosphoribosyl 1-pyrophosphate in human erythrocytes. A 31P-n.m.r. study.

Incubation of human erythrocytes in medium containing inosine (10 mM), pyruvate (10 mM), phosphate (50 mM) and NaCl (75 mM) at pH 6.6 leads to a more than 1000-fold increase in the concentration of 5-phosphoribosyl 1-pyrophosphate (PRPP), as identified and quantified by 31P-n.m.r. spectroscopy. The accumulation is highly pH-dependent, with a maximum at extracellular pH 6.60, and the maximum value of 1.3-1.6 mmol/l of erythrocytes is attained within 1 h at 37 degrees C. PRPP was accumulated despite high concentrations of 2,3-bisphosphoglycerate (2,3-BPG), an inhibitor of PRPP synthetase. The concentration of PRPP correlated with the intracellular concentration of inorganic phosphate (Pi). Substitution of either adenosine or adenosine plus inosine for inosine in the medium did not lead to 31P-n.m.r.-detectable accumulation of PRPP. These results show that neither 2,3-BPG nor PRPP itself inhibits the synthesis of PRPP in the human erythrocyte. Adenosine, however, prevents the inosine-stimulated accumulation of PRPP.

Adenosine↗
PubMed1990

Induction of millimolar amounts of 5-phosphoribosyl-1-pyrophosphate in human erythrocytes by incubation in inosine-pyruvate-phosphate medium. A 31P-NMR study.

Incubation of human erythrocytes in inosine (10 mM), pyruvate (10 mM), phosphate (50 mM) and NaCl (75 mM) (IPP-medium)1 at pH 6.6 leads to a ca. 1000 fold increase in the concentration of 5-phosphoribosyl-1-pyrophosphate (PRPP) as identified and measured by 31P-NMR spectroscopy. PRPP accumulation is pH-dependent with a maximum at extracellular pH 6.60 and the maximum value of 1.3-1.6 mmol/l RBC is reached within one hour at 37 degrees C. PRPP accumulated despite high concentrations of 2,3-diphosphoglycerate (2,3-DPG), an inhibitor of PRPP-synthetase. The concentration of PRPP attained correlated with the intracellular concentration of inorganic phosphate (P1). Substitution of either adenosine or adenosine plus inosine for inosine in the medium (APP or A+IPP media) did not lead to NMR detectable accumulation of PRPP, despite the same high concentrations of intracellular P1. The lack of accumulation of PRPP in adenosine containing media may be related to the higher concentrations of nucleoside diphosphates induced in these media. These results show that neither 2,3-DPG nor PRPP itself inhibit the synthesis of PRPP in the human erythrocyte under these circumstances.

Erythrocytes↗
PubMed1990

[The course of phobia in children and adolescents: a catamnestic study].

18 out of 25 patients with phobia, who were treated in a child psychiatric clinic at the age of 8.2-17.5 years took part in a follow-up-study. Mean follow-up time was 5.2 years. Patients were interviewed with the "Struktured Clinical Interview for DSM-IIIR" (SKID) and filled in following questionnaires: Symptom Check List (SCL 90 R), State-Trait-Anxiety-Inventory, (STAI) and Interaction-Anxiety-Questionnaire (Interaktions-Angst-Fragebogen (IAF). Psychiatric disorders were diagnosed in 7 out of 18 patients. Predicter of outcome was the type of phobia. While at follow-up 4 out of 8 patients with a previous diagnosis of "Simple Phobia" (DSM-IIIR: 300.29) still suffered from distinct psychiatric disorders (DSM-IIIR criteria), outcome for patients with agoraphobia and social phobia was better. Age at onset duration of symptoms before treatment, age at start of treatment, and duration of therapy did not predict outcome.

Adolescent↗
PubMed1989

The Na+/K+-ATPase reaction of human erythrocytes is not near equilibrium. A 31P-NMR study.

We have addressed the question of whether the Na/K+-ATPase in the human erythrocyte is in a state of near-equilibrium by varying the extracellular ratio of Na+ and K+ and following the cytosolic phosphorylation potential by 31P-NMR and by combined enzymatic colorimetric measurements. There was no correlation at room temperature between the extracellular Na+/K+ ratio and the cytosolic phosphorylation potential measured either by NMR or alternative methods. The cytosolic phosphorylation potential measured by NMR was 4100 +/- 1300 (S.E.) M-1 at an extracellular K+ concentration of 5.9 mM (Na+/K+ ratio of 24.3) and 2800 +/- 700 (S.E.) M-1 at 75 mM extracellular K+ (Na+/K+ ratio of 0.99). The chemically determined phosphorylation potential was 6400 +/- 1200 (S.E.) and 5000 +/- 700 (S.E.) M-1 at 5.9 and 75 mM extracellular K+, respectively. Omission of Ca2+ from the buffer solutions did not affect the results. A consistent finding in this study was that the NMR-determined value of ATP was about 10-20% lower than the value determined enzymatically on perchloric acid extracts. The inorganic phosphate (Pi) was fully NMR visible.

Calibration↗
PubMed1989

In-vitro sensitivity of Hodgkin's disease to hydrogen peroxide toxicity. Correlation with peroxidase activity.

Hodgkin's disease of nodular sclerosis and mixed cellularity subtypes contains numerous eosinophils and substantial amounts of extracellular eosinophil peroxidase (EPO). To determine if the extracellular EPO retains cytotoxic activity, the authors analyzed cells from 13 cases of Hodgkin's disease and ten cases of benign lymphoid hyperplasia for their in vitro sensitivity to killing by a low concentration of hydrogen peroxide. Cells from cases of benign lymphoid hyperplasia (0.5% +/- 1% killing) and lymphocyte predominant Hodgkin's disease (4.5% +/- 6% killing) were significantly (P less than 0.05) less sensitive to killing by hydrogen peroxide than cells from nodular sclerosis Hodgkin's disease (26% +/- 13% killing) and mixed cellularity Hodgkin's disease (52% +/- 9% killing). The authors concluded that cells from Hodgkin's disease of nodular sclerosis and mixed cellularity subtypes have an increased sensitivity to killing by an otherwise nonlethal concentration of hydrogen peroxide.

Cell Survival↗
PubMed1989

[Production and characterization of monoclonal antibodies against allergen components].

Monoclonal antibodies are useful tools for characterizing components causing type I allergy. Three aspects in production and characterization of monoclonal antibodies are discussed: 1. production of monoclonal antibodies raised against a special allergen of rye pollen extract. 2. investigation of monoclonal antibodies raised against peptide fragments of ovalbumin, 3. analysis of epitopes on allergenic components of timothy pollen extracts. The results indicate that monoclonal antibodies raised against certain allergens are useful for isolation of allergenic components and epitope mapping.

Animals↗