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Biomedical subjects

P Andersen

Publications and source records attributed to P Andersen.

At least 307 records · Page 17Linked to original sources
PubMed1979

Incidence and titres of smooth-muscle antibodies in human sera.

By means of the indirect immunofluorescence method smooth-muscle antibodies (SMA) were determined in 182 patients with various diseases and the findings were compared with those of 7 patients with chronic active hepatitis (CAH) and 580 normal controls. IgG-SMA were found in 85.7% of the patients with CAH, titres above 80 occurred only in Hepatitis B-associated antigen (HBAg)-negative CAH, but IgG-SMA in low titres were also found with increased incidence in syphilis (16.7%) and in infections of the central nervous system (19%). In other diseases (Sjøgren's syndrome, ulcerative colitis, regional enteritis, myasthenia gravis, progressive muscular dystrophy, atopic dermatitis and mycoplasma pneumoniae infection) the prevalence did not differ from that of controls (3.6%). IgM-SMA were found more often in CAH (28.6%), in infections of the central nervous system (14.3%) and in the mycoplasma pneumoniae infections (13%) than in controls (2.6%), but titres above 20 occurred only in controls. IgA-SMA were detected only in a patient with syphilis. Demonstration of IgG-SMA titres above 80 seems to support the diagnosis of HBAg-negative CAH, while the demonstration of IgA- and IgM-SMA seems to be without diagnostic value in chronic hepatitis.

Adolescent↗
PubMed1979

Reactivity of smooth-muscle antibodies with F- and G-actin.

The reactivity of human smooth-muscle antibodies (SMA) with F- and G-actin was investigated by means of an enzyme-linked immunosorbent assay (ELISA). Polystyrene tubes were coated with F-actin, G-actin and tropomyosin. The optimal reactivity of SMA with F-actin was achieved with tubes coated with actin concentrations in the range of 10-100 mug/ml, while both lower and higher amounts yielded lower reactivity. The reactivity with G-actin was low and only a little higher than the reactivity with tropomyosin or uncoated tubes, but much lower than the reactivity with F-actin. The differences in reactivity of SMA with F- and G-actin could not be explained by differences in binding of the two forms of actin to the tubes, although 1.7-2.5 times more F-actin than G-actin bound to the polystyrene surface after coating with equivalent amounts of protein. SMA-negative sera did not react with F-actin coated tubes indicating that the binding of antibody was not due to non-immunological binding of immunoglobulins. Human SMA thus react better with F- than with G-actin.

Actins↗
PubMed1978

Functional characteristics of unmyelinated fibres in the hippocampal cortex.

(1) In transverse hippocampal slices (350 micrometer thick), taken from guinea pigs initially anaesthetized with ether, intracortical afferent fibres were activated by small current pulses delivered through tungsten microelectrodes. Extracellular potentials were recorded from the zone of activated fibres in dendritic layers while intracellular recordings were made from the soma of CA1 pyramidal cells. (2) When recording was made from the same level as the stimulating cathode, the extracellular potential consisted of a diphasic deflection followed by a larger negative wave with a superimposed population spike. The negative wave corresponded to an intracellularly recorded EPSP, and is called an extracellular EPSP, whereas the initial diphasic deflection had no intracellular counterpart. (3) The initial diphasic deflection was linearly related to the size of both the intracellular and extracellular EPSP. It was not changed by removal of calcium ions from the bathing fluid, whereas all postsynaptic activity disappeared. The diphasic deflection was propagated along fibres lying parallel to the pyramidal layer with a velocity of 0.3 m/sec. It could follow short bursts of stimulation at 300 Hz. The absolute refractory period was 2.0 msec. (4) The initial diphasic deflection is interpreted as the compound action potential of the largely unmyelinated afferent fibres to the CA1 neurones.

Afferent Pathways↗
PubMed1978

Antibodies to smooth muscle and other tissue components in infectious mononucleosis.

Antibodies to tissue components were studied by the indirect immunofluorescent method in 24 patients with infectious mononucleosis (IM). Smooth-muscle antibodies (SMA) were found in 70.8% of the patients, and in only one (3.8%) of 26 controls. SMA in patients were of the IgG (54.2%), the IgA (12.5%) and the IgM (41.6%) class. IgM-SMA occurred in the early phase of the disease, while IgG-SMA were found both early and late in its course. It was not possible to demonstrate that the development of SMA was due to liver involvement. Antinuclear antibodies, parietal-cell antibodies and antibodies to the cytoplasm of renal tubular cells were not detected significantly more often in patients than in controls. The serum concentrations of IgG, IgA and IgM were elevated in the acute phase of IM, and it was found that the Ig values were higher in patients with SMA than in those without.

Adolescent↗
PubMed1978

Immunoglobulin levels and specific viral antibodies in relation to smooth-muscle antibodies in cytomegalovirus infection.

Among 17 patients with cytomegalovirus (CMV) infection smooth-muscle antibodies (SMA) of the IgM class were detected in 9 (53%) and IgG-SMA in 6 (35%), while no IgA-SMA were found. IgM-SMA were present most often and in the highest titres (10-160) in the beginning of the disease, while IgG-SMA were found both early and late during the course of infection. SMA occurred most frequently in patients with specific CMV antibodies of the IgM class and in patients with elevated serum alanine aminotransferase values, but these relationships were not significant. Elevated levels of serum IgG, IgA and IgM were found in CMV infection, and a correlation between serum IgM values and IgM-SMA titres was demonstrated (alpha less than 0.01). A similar correlation between serum IgG and IgG-SMA could not be established. These findings are in support of the assumption that IgM-SMA account for a minor part of the elevated serum IgM levels in CMV infection, but not of the hypothesis that the stimulus for antibody production is the release of antigens from liver cells.

Adolescent↗
PubMed1977

Long-lasting facilitation of synaptic transmission.

After tetanization of several hippocampal pathways (10--50 Hz for 5--15 seconds) there is an increased synaptic transmission of long duration (long-lasting facilitation). The present investigation was undertaken on isolated hippocampal slices to study the mechanism of the effect. The transverse hippocampal slice preparation in vitro allows the simultaneous testing of several afferent fibre systems on the same cell or population of cells. Tetanization of one group of afferent fibres to CA1 pyramids was followed by a long-lasting increase of synaptic transmission along the same fibres, whereas a control input line gave unchanged responses. Using the presynaptic volley as an indicator of the number of afferent impulses, the increased synaptic transmission appeared as an increased excitatory postsynaptic potential (EPSP), increased amplitude and reduced latency of the population spike, and an increased probability of firing of single units. Intracellular recording showed increased EPSPs to afferents of the tetanized line, but no lasting change in membrane resistance or in the response to a depolarizing current pulse. Thus, the effect cannot be ascribed to a general postsynaptic excitability increase. The specific changes in the synaptic transmission may be due either to an increased amount of liberated transmitter or to a local postsynaptic change near the tetanized synapses.

Afferent Pathways↗
PubMed1977

Immunoglobulin levels and autoantibodies in epileptics on long-term anticonvulsant therapy.

Serum immunoglobulin (Ig) levels and various autoantibodies have been determined in 53 epileptics treated with anticonvulsant drugs for more than 10 years and in 53 controls matched for age and sex. Aberrations in both IgG, IgA and IgM values were demonstrated. The mean IgG concentration was significantly lower in epileptics (1217 mg/100 ml) than in controls (1364 mg/100 ml) p less than 0.05). The mean IgA value was 161 mg/100 ml in both patients and controls (F-test, p less than 0.01), but abnormally low IgA values were found in 17%, and abnormally high values in 11% of the epileptics. The mean IgM concentration was 157 mg/100 ml in epileptics and 117 mg/100 ml in controls (F-test, p less than 0.01). Autoantibodies were found significantly more often in epileptics (26.4%) than in controls (3.8%) (2p less than 0.002). The occurrence of autoantibodies could not be related to alterations in the Ig levels. Neither was it possible to correlate the occurrence of mitochondrial antibodies, smooth muscle antibodies and antinuclear antibodies to the slightly abnormal biochemical liver parameters found in these patients. Thus, the abnormalities in Ig levels and the autoimmune phenomena observed in epileptics on long-term anticonvulsant therapy are not intimately related.

Adolescent↗
PubMed1977

ECG recording in emergency home visits.

During the first half of 1974, 756 emergency home calls have been made by 6 doctors in the City of Oslo. A portable ECG instrument was available at all visits. The visits were unselected as regards complaints. ECG was recorded in 7% of all patients and in 19% of all patients over 60 years of age. The main indication for recording an ECG was chest pain (nearly 2/3 of all recordings). In only a small number of cases did the recording give a definite result as regards diagnosis of management of the case. However, a slight additional benefit was obtained with a majority of the ECG recordings, including what we defined as a phychotherapeutic benefit. The results of this study indicate that the value of a portable electrocardiograph is very limited for emergency home calls in a city.

Adolescent↗
PubMed1977

Fiber types and metabolic potentials of skeletal muscles in sedentary man and endurance runners.

This description of some of the present knowledge on skeletal muscle fibers, their metabolic potentials, and their interplay with the degree of physical activity has revealed that skeletal muscle of man has a very large capacity for adaptation. Moreover, this adaptability appears to be of utmost importance for the metabolic response as well as for performance. Although all this is true, it should not distract us from the fact that we are lacking the most important information. The questions that need to be answered are: What triggers the changes to take place? Which are the regulatory mechanisms?

Adaptation, Physiological↗
PubMed1977

Capillary supply of the quadriceps femoris muscle of man: adaptive response to exercise.

1. Five subjects trained for 8 weeks on a bicycle ergometer for an average of 40 min/day, four times a week at a work load requiring 80% of the maximal oxygen uptake (V(O2 max.)). V(O2 max.) determinations were performed, and muscle biopsies from the quadriceps femoris muscle (vastus lateralis) were taken before, as well as repeatedly during, the training period. The muscle biopsies were histochemically stained for fibre-types (myofibrillar ATPase) and capillaries (amylase-PAS method), and analysed biochemically for succinate dehydrogenase and cytochrome oxidase activities.2. The training programme resulted in a 16% increase in V(O2 max.), a 20% increase in capillary density, a 20% increase in mean fibre area, and an approximately 40% increase in the activities of succinate dehydrogenase and cytochrome oxidase.3. The capillary supply to type I, IIA and IIB fibres, expressed as the mean number of capillaries in contact with each fibre-type, relative to fibre-type area, increased equally.4. The present study shows that endurance training constitutes a powerful stimulus for capillary proliferation in human skeletal muscle.

Adaptation, Physiological↗
PubMed1977

The anticoagulant effect of heparin + antithrombin III using purified fibrinogen as substrate.

The anticoagulant effect of heparin in test systems composed of purified factors [antithrombin III (AT-III), fibrinogen and thrombin] was studied. As expected, the sensitivity to heparin depended on the concentrations of AT-III and thrombin, whereas the fibrinogen level was less decisive. In addition, qualitative differences proved important. Thus, the sensitivity to heparin was greater with crude bovine thrombin than with highly purified thrombin from the same species. Further, the sensitivity to heparin increased following removal of cold-insoluble material from the fibrinogen preparation. Finally, during storage of purified AT-III at +4 degrees C for more than 4 weeks, the sensitivity to heparin decreased more rapidly than expected from the amidolytic AT-III assays. Smaller amounts of heparin were required to give a prolonged thrombin clotting time than in whole plasma, indicating that components of normal platelet-poor plasma (besides AT-III and fibrinogen) interfere with the anticoagulant effect of heparin. The present test systems may prove suitable for the detection and evaluation of factors of importance for the so-called heparin tolerance.

Animals↗
PubMed1977

The antiheparin effect of alpha1-acid glycoprotein and platelet material, evaluated by the heparin thrombin clotting time.

The effect on the heparin thrombin clotting time (HTCT) of a so-called acute phase protein, alpha1-acid glycoprotein, was studied in test systems consisting of purified fibrinogen, antithrombin III, heparin and thrombin, and compared to the effect of platelet material (crude platelet factor 4). In these test systems a physiological concentration of alpha1-acid glycoprotein (1 g/l) inhibited heparin more effectively than did soluble platelet material from 200 X 10(9) platelets/l. The present observations suggest that alpha1-acid glycoprotein is of great significance for the so-called heparin tolerance, whereas platelet material proved less important.

Blood Coagulation Factors↗