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Biomedical subjects

P Andersen

Publications and source records attributed to P Andersen.

At least 235 records · Page 13Linked to original sources
PubMed1985

Maximal perfusion of skeletal muscle in man.

Five subjects exercised with the knee extensor of one limb at work loads ranging from 10 to 60 W. Measurements of pulmonary oxygen uptake, heart rate, leg blood flow, blood pressure and femoral arterial-venous differences for oxygen and lactate were made between 5 and 10 min of the exercise. Flow in the femoral vein was measured using constant infusion of saline near 0 degrees C. Since a cuff was inflated just below the knee during the measurements and because the hamstrings were inactive, the measured flow represented primarily the perfusion of the knee extensors. Blood flow increased linearly with work load right up to an average value of 5.7 l min-1. Mean arterial pressure was unchanged up to a work load of 30 W, but increased thereafter from 100 to 130 mmHg. The femoral arterial-venous oxygen difference at maximum work averaged 14.6% (v/v), resulting in an oxygen uptake of 0.80 l min-1. With a mean estimated weight of the knee extensors of 2.30 kg the perfusion of maximally exercising skeletal muscle of man is thus in the order of 2.5 l kg-1 min-1, and the oxygen uptake 0.35 l kg-1 min-1. Limitations in the methods used previously to determine flow and/or the characteristics of the exercise model used may explain why earlier studies in man have failed to demonstrate the high perfusion of muscle reported here. It is concluded that muscle blood flow is closely related to the oxygen demand of the exercising muscles. The hyperaemia at low work intensities is due to vasodilatation, and an elevated mean arterial blood pressure only contributes to the linear increase in flow at high work rates. The magnitude of perfusion observed during intense exercise indicates that the vascular bed of skeletal muscle is not a limiting factor for oxygen transport.

Adult↗
PubMed1985

Dynamic knee extension as model for study of isolated exercising muscle in humans.

In an attempt to approach a system of isolated exercising muscle in humans, a model has been developed that enables the study of muscle activity and metabolism over the quadriceps femoris (QF) muscles while the rest of the body remains relaxed. The simplest version includes the subject sitting on a table with a rod connecting the ankle and the pedal arm of a bicycle ergometer placed behind the subject. Exercise is performed by knee extension from a knee angle of 90 to approximately 170 degrees while flywheel momentum repositions the relaxed leg during flexion. Experiments where electromyographic recordings have been taken from biceps femoris, gastrocnemius, tibialis anterior, and other muscles in addition to QF indicate that only the QF is active and that there is an equal activation of the lateral, medial, and rectus femoris heads relative to maximum. Furthermore, virtually identical pulmonary O2 uptake (Vo2) during and without application of a pressure cuff below the knee emphasizes the inactivity of the lower leg muscles. The advantages of the model are that all external work can be localized to a single muscle group suitable for taking biopsies and that the blood flow in and sampling from the femoral vein are representative of the active muscles. Thus all measurements can be closely related to changes in the working muscle. Using this model we find that a linear relationship exists between external work and pulmonary Vo2 over the submaximal range and the maximal Vo2 per kilogram of muscle may be as much as twice as high as previously estimated.

Adult↗
PubMed1985

Serum antibodies to Aspergillus fumigatus in Danish farmers.

182 Danish farmers and 105 city-dwelling control subjects were investigated for serum IgG antibodies to three purified Aspergillus fumigatus antigen fractions and unfractionated culture filtrate by enzyme-linked immunosorbent assay (ELISA). Farmers had higher levels of antibodies to all four ELISA antigens than non-farming controls. In farmers and controls high antibody activity was recorded with an antigen fraction of approximate molecular weight 470 000 daltons. Antibody levels to this fraction were higher in non-smokers than smokers in both study groups. Cattle farmers had higher antibody levels to the 470 000 daltons fraction than farmers with no animals on the farm. Farmers with higher antibody activity to any of the three fractionated ELISA antigens tended to have fewer respiratory symptoms than farmers with lower antibody activity. It was concluded that occupational exposure and smoking habits are the main determinants of the immune response to A. fumigatus in man.

Adolescent↗
PubMed1984

Effects of bovine serum albumin on antibody determination by the enzyme-linked immunosorbent assay.

The effect of bovine serum albumin (BSA) post-coating and addition of BSA to serum diluent was studied in an IgG and IgA Candida antibody enzyme-linked immunosorbent assay (ELISA). BSA post-coating decreased the background readings and increased the specific Candida antibody activity in most sera. However, in a few sera post-coating alone increased background readings and this effect was probably due to the occurrence of BSA antibodies. It could be abolished by the addition of BSA to serum diluent. It is therefore suggested that BSA post-coating should only be used in combination with BSA addition to serum dilution buffer in ELISA.

Adolescent↗
PubMed1984

Current-to-frequency transduction in CA1 hippocampal pyramidal cells: slow prepotentials dominate the primary range firing.

In order to study how hippocampal pyramidal cells transform a steady depolarization into discharges, CA1 pyramids (n = 32) were injected with 1.5 s long pulses of constant depolarizing current. The firing in response to weak currents was in most cells, characterized by low frequency (0.2-5 Hz), slowly increasing depolarizations preceding each action potential (slow prepotentials, SPPs), a long latency (0.2-5 s) to the initial spike and lack of adaptation. The SPPs, which lasted 30-2,000 ms, showed an increasing steepness with increasing current, and seemed to be a major regulating factor for the slow firing. In response to stronger currents the discharge had a high initial frequency (100-350 Hz), followed by adaptation to steady state firing (5-50 Hz). Thirty of 32 cells showed a dip in the frequency (n = 5), or a pause (n = 25) lasting 250-1,000 ms between the initial burst of firing and the steady state. The pause occurred only at intermediate current strengths. Additional spikes to the initial burst seemed to be recruited through the development of depolarizing waves. The initial slope of these waves resembled those of the SPPs. Similar waves occurred at the expected time of occasionally missing spikes during steady state firing. The variability (SD/mean) of the interspike intervals decreased with increasing frequency of firing. The frequency-current (f/I) relation for the steady state firing showed a simple linear or convex shape, and lacked a secondary range. In contrast, the f/I plots for the initial few interspike intervals had both primary, secondary and tertiary ranges, like motoneurones.

Action Potentials↗
PubMed1984

Antibodies to hen and duck antigens in poultry workers.

Serum antibodies to avian and Aspergillus antigens were detected by enzyme-linked immunosorbent assays (ELISA) in forty-two workers from a poultry abattoir and in twenty healthy blood donors. The levels of IgG and IgA antibodies to hen and duck serum were significantly higher in poultry workers than in blood donors (P less than 0.01). In workers employed for less than 1 year the antibody levels were lower than in those who had been employed for a longer period of time (P less than 0.05). The IgA antibody level to a high molecular weight Aspergillus antigen was higher in poultry workers than blood donors (P less than 0.05), whereas the level of other Aspergillus antibodies were similar in the two groups. The level of IgG antibodies to hen antigen was higher in non-smokers than in smokers (P less than 0.02). A correlation between the antibody levels to hen and duck antigens and to pigeon antigen was found (P less than 0.05), indicating cross-reactivity between these antibodies. No cases of allergic alveolitis were found, and no correlation between antibody levels and respiratory symptoms could be demonstrated.

Adolescent↗
PubMed1984

Serum IgA antibodies to Aspergillus fumigatus determined by enzyme-linked immunosorbent assay.

Serum IgA antibodies to three Aspergillus fumigatus antigen fractions were determined by enzyme-linked immunosorbent assay (ELISA) in 13 patients with aspergilloma, 23 patients with aspergillus lung infiltrates, 8 patients with allergic broncho-pulmonary aspergillosis (ABPA), and 113 healthy blood donors. All three groups of patients had higher median serum IgA antibody levels against the three antigen fractions than healthy subjects. Thirty six (82%) of 44 patients had IgA antibody values to at least one antigen fraction above the 95 percentile of the blood donor group. Patients with aspergillomas and aspergillus lung infiltrates had slightly higher IgA antibody levels than ABPA patients. Determination of serum IgA antibodies to A. fumigatus antigen fractions had a lower diagnostic efficacy than previously found for IgG antibodies.

Adolescent↗
PubMed1984

Antibiotic treatment of pneumonia and bronchiolitis. A prospective randomised study.

Routine administration of antibiotics in the treatment of pneumonia and bronchiolitis in infants and small children was evaluated in an open randomised prospective trial. From 1979-82 136 children between the age of 1 month and 6 years were allocated to one of two treatment groups shortly after their admission to a paediatric ward. Group A patients were to be given antibiotics but those in group B were not. None of the children had received antibiotics before hospital admission. A viral infection was diagnosed in 38 of the 72 patients from group A and in 34 of the 64 patients from group B. Respiratory syncytial virus was detected in 84% of these patients. Samples of tracheal secretions showed no differences between the groups in respect of cytology and bacterial flora. Nor were there any significant differences in the course of acute disease, the frequency of fever relapse and pulmonary complications. Fifteen patients from group B were subsequently treated with antibiotics: two of these developed secondary purulent infections of the middle ear and one showed a slight pleural effusion. These results do not support the routine use of antibiotics in infants and small children admitted to hospital with pneumonia and bronchiolitis.

Anti-Bacterial Agents↗
PubMed1984

Fractionation of Aspergillus fumigatus antigens by hydrophobic interaction chromatography and gel filtration.

Aspergillus fumigatus somatic antigen prepared from young hyphae was fractionated by hydrophobic interaction chromatography followed by gel filtration. The antigenic activity of fractions was investigated by enzyme-linked immunosorbent assay, crossed immunoelectrophoresis, and immunodiffusion. By enzyme-linked immunosorbent assay, high levels of IgG antibodies were detected against an antigen fraction of approximate molecular weight 470,000 both in patients with aspergillosis (n = 3) and in healthy controls (n = 3). High levels of antibodies to four fractions of MW 250,000 160,000, 160,000-50,000, and 50,000-25,000 were found only in patients. The MW 250,000 fraction exhibited catalase activity, and the MW 50,000-25,000 fraction had neutral protease activity. These purified aspergillus antigens may be useful in serodiagnosis of aspergillosis.

Adult↗
PubMed1984

IgG antibodies to purified Aspergillus fumigatus antigens determined by enzyme-linked immunosorbent assay.

IgG antibodies to three purified Aspergillus fumigatus antigens were determined by enzyme-linked immunosorbent assay (ELISA) in sera from 26 patients with definite pulmonary aspergillosis (group 1), 23 patients with suspected pulmonary aspergillosis (group 2), 8 patients with precipitating antibodies to A. fumigatus of undetermined clinical significance (group 3), and 113 healthy blood donors (group 4). With a 470,000-dalton antigen fraction ELISA values exceeded the upper range of group 4 (0.72) in 92, 91 and 13% of cases in groups 1, 2 and 3, respectively. With a 250,000-dalton antigen fraction the figures were 96, 78 and 13%, respectively (upper range of group 4 = 0.25). With an antigen fraction of 25,000-50,000 daltons the figures were 96, 65 and 13%, respectively (upper range of group 4 = 0.18). In 48 of 49 cases of definite or suspected aspergillosis (groups 1 + 2) ELISA values with at least one antigen exceeded the upper range of controls (group 4). It appears that antibody determination with these three antigen fractions may have a high diagnostic sensitivity.

Adolescent↗
PubMed1983

Serum antibodies to pigeon antigens in smokers and nonsmokers.

Antibodies to pigeon antigens were determined by double immunodiffusion and ELISA in 80 pigeon breeders without pigeon breeder's disease. Precipitating antibodies to pigeon serum and droppings were found in 5 and 8%, respectively, of 39 breeders who were smokers and in 46 and 51%, respectively, of 41 breeders who were nonsmokers (p less than 0.001). By ELISA, IgG antibodies to pigeon serum and droppings were detected in 44 and 54%, respectively, of smokers and in 81 and 85%, respectively, of nonsmokers (p less than 0.01). The antibody titres were generally higher in nonsmokers than in smokers. These findings may partly explain why allergic alveolitis occurs most often in nonsmokers.

Adolescent↗
PubMed1983

Complement-binding antibodies to Aspergillus fumigatus in patients with pulmonary aspergillosis.

Complement-binding antibodies against Aspergillus fumigatus were determined by a fluorescent antibody technique with purified human Clq as the source of complement. Clq binding aspergillus antibodies were found in 8 (67%) of 12 patients with pulmonary aspergillosis, in 4 (57%) of 7 patients with suspected pulmonary aspergillosis, in one (14%) of 7 patients with precipitating antibodies to A. fumigatus of undetermined clinical significance, and in 4 (7%) of 54 healthy blood donors. Sera from patients with definite or probable aspergillosis produced an immunofluorescent staining of hyphal cytoplasm, whereas the staining obtained with positive donor sera was confined to hyphal walls. A positive correlation was found between the frequency and titres of Clq binding antibodies and titres of IgG and IgM aspergillus antibodies. Clq binding antibodies were found only in sera with an IgG aspergillus antibody titre greater than or equal to 640. The frequency of Clq binding antibodies in sera with IgG titres greater than or equal to 640 was significantly higher in patients with aspergillosis (67%) than in blood donors (16%) (p = 0.0036). The Clq binding antibody test may provide diagnostic information as well as clues to the pathogenesis of aspergillus lung disease.

Adolescent↗