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Biomedical subjects

I Andersen

Publications and source records attributed to I Andersen.

At least 91 records · Page 5Linked to original sources
PubMed1979

Human response to controlled levels of inert dust.

We studied nasal mucous flow, airway resistance, and subjective response in 16 young healthy subjects during 5-hour exposures to 2, 10, and 25 mg of inert dust per m3 in an environmental chamber. The dust was a fully polymerized plastic dust containing carbon black. The number of these particles in room air, expressed as a per cent of the total number of particles was 36, 41, 14, 7, and 2, respectively, for the aerodynamic size ranges less than or equal to 1.8, 1.9 to 5.3, 5.4 to 8.9, 9.0 to 12.4, and greater than or equal to 12.5 micron. No significant changes in nasal mucociliary clearance rate or nasal resistance were observed. At all dust concentrations there was a decrease in 1-sec forced expiratory volume, but not in the forced vital capacity or the forced expiratory flow during the middle half of the forced vital capacity. The nasal penetration fraction of particles was approximately 55 per cent for the smallest particles and 20 per cent for the largest particles. Discomfort was proportional to the concentration of dust, but lagged almost 2 hours behind the changes in dust concentration. The discomfort was never excessive; the main complaints were dryness in the nose and pharynx.

Adult↗
PubMed1979

The effects of moderate heat stress on mental performance.

Moderate heat stress is believed to affect mental performance by lowering levels of arousal. Conscious effort can counteract this effect. In most experiments, raised temperatures are perceived at the start by subjects and can act as a stimulus to exert conscious effort. In practice, temperatures usually rise slowly and may therefore have a more marked effect. Thirty-six male and 36 female 17-year-old subjects in standard cotton uniforms (0.7 clo) were exposed in groups of four in a climate chamber to rising air-temperature conditions typical of occupied classrooms, in the range 20--29 degrees C. The maximum rate of rise was 4 degrees C/h. Each group performed mental work during three successive periods of 50 min with 10-min breaks between. During each break the air temperature was reduced by 3 degrees C. Sentence comprehension was significantly reduced by intermediate levels of heat stress in the third hour. A multiplication task was performed significantly more slowly in the heat by male subjects, showing a minimum at 28 degrees C. Recognition memory showed a maximum at 26 degrees C, decreasing significantly at temperatures below and above, and an independent measure of degree of certainty in recall showed a maximum at 27 degrees C. These findings are in accordance with the hypothesis of reduced arousal in moderate heat stress in the absence of conscious effort.

Adolescent↗
PubMed1978

Nasal mucociliary clearance in man.

Nasal mucociliary clearance was measured in healthy young human subjects and tracheal clearance in the experimental animal under a wide variety of conditions. There is a broad range of clearance rates whether at standard ambient conditions (23 degrees C, 50% relative humidity) or in the face of a number of environmental variables. The degree to which those differences are attributable to the effectiveness of ciliary beating or the character of airway secretions is not known. Studies of tracheobronchial secretions simultaneous with clearance measurement in the anaesthetized dog have not yet provided a definite answer. Variations in upper respiratory defence mechanisms may bear some relationship to the aetiology of small airway disease in the lungs.

Adult↗
PubMed1978

Topochemistry of trace metals in nasal mucosa. Potentialities of some histochemical methods and energy dispersive X-ray microanalysis.

Histochemical methods and energy dispersive X-ray micro-analysis (EDX-analysis) were evaluated in model experiments and on tissue sections for their usefulness in detecting traces of metals in biological tissue. The goal for this study was to establish a method for localization of nickel deposits in the nasal mucosa, where it has been found in concentrations between 1 and 40 microgram/g in nickel exposed individuals. The histochemical methods tested were staining with dimethylglyoxime, rubeanic acid and dithizone, the Turnbull and Prussian blue methods and TIMM'S sulphide silver procedure. In model experiments nickel-, cobalt-, copper-, zinc- and ironsalts were applied to thin-layer chromatography sheets (TLC-sheets) and stained by the histochemical methods. Spots containing 500 and 50 ng of these metals represented the smallest amounts that could consistently be detected in these experiments, except for the sulphide silver method which seemed a little more sensitive. With the latter method, moreover, zinc was detected in 40 micrometer thick cryostat sections of gelatine made up with 1 microgram/g of the metal. For nickel the corresponding figure was 10 to 50 microgram/g. On specimens of nasal mucosa from nickel-exposed workers, a faint colour was obtained in 40 micron thick cryostat sections from specimens that had been immersed in dithizone, but the colour was too weak for histological analysis. None of the other coloured chelating agents caused noticeable staining when applied to blocks or to cryostat sections. TIMM'S sulphide silver method caused strong staining of the basal layers of the surface epithelium and of fibroblast-like cells in the underlying connective tissue. This staining pattern is described in more detail in a separate report. Rat liver tissue was analyzed by atomic absorption before and after araldite embedding. Blocks of gelatine made up with nickel, copper, zinc and iron were embedded in epoxy resin and analyzed by atomic absorption. Large changes in the metal concentrations, usually an increase, were found after embedding. Ultrathin sections from this material were used to test the sensitivity of the EDX-equipment. Referring to the concentrations determined by atomic absorption in the embedded material, iron was detected at 1215 microgram/g and 362 microgram/g (gelatine standards) but not at 167 microgram/g (rat liver). Similar values could not be determined for nickel, copper or zinc, because of background radiation resulting from the presence of these metals in the instrument. We did not succeed in establishing a procedure for detecting nickel deposits in nasal mucosa with any of the methods which were tested. The most sensitive but least specific of the tested methods for visualizing heavy metals in the nasal mucosa, was TIMM'S sulphide silver procedure. The preparation of tissue for this method is discussed.

Animals↗
PubMed1978

Analysis for nickel in plasma and urine by electrothermal atomic absorption spectrometry, with sample preparation by protein precipitation.

We describe and evaluate a method for determining nickel in plasma and urine by atomic absorption spectrometry. Proteins are precipitated with trichloroacetic acid and sulfuric acid; ammonium pyrrolidinedithlocarbamate is used as the chelating agent for nickel, and methyl isobutyl ketone as extraction solvent. The results were compared with results obtained by the acid-digestion technique for removing proteins and other organic substances. Analyses for both plasma and urine were better by the present procedure. The mean and standard deviation for nickel in plasma from 15 healthy individuals was 2.13 +/- 0.58 microgram/liter by this method. For nickel in urine from 15 healthy men the mean and standard deviation was 4.45 +/- 1.9 microgram/liter. The coefficient of variation for plasma was 11.9%, and for urine 12.2% in 10 analyses of the same plasma and urine with the protein-precipitation procedure, as compared with 26.0 and 38.2%, respectively, by the acid-digestion technique.

Adult↗
PubMed1977

Human nasal mucosal function at controlled temperatures.

We exposed 16 healthy human volunteers to air temperatures ranging from 7 to 39 degrees C and measured nasal mucus flow, nasal airflow resistance, forced vital capacity, rectal and body surface temperature, and air temperature within the nasal passage. A moderate fall in nasal mucus flow rate in the anterior and middle parts of the nose was observed with temperature above or below 23 degrees C. The nasal airflow resistance decreased in warm air and tended to increase in cold air. No significant changes in forced vital capacities or rectal temperature were observed. Nasopharyngeal end inspiratory air temperatures at 23 degrees C averaged 32.6 degrees C. At environmental temperatures of 15 and 31 degrees C they average 28.1 and 32.8 degrees C, respectively. Although we found alterations in upper airway function associated with altered inspired air temperature, over the range of 32 degrees C studied these changes were of minor physiological significance.

Acclimatization↗
PubMed1977

Nasal cancers, symptoms and upper airway function in woodworkers.

In 186 cases of nasal cancer diagnosed over the decade 1965-74, in a population of 2-0 million, 114 of 157 ectodermal tumours were found in men. Adenocarcinoma was found in 17 patients, two women and 15 men; 12 of these had a history of occupational exposure to wood dust in the furniture industry. The period of latency was from 28 to 57 years. Among the remaining 99 tumours in men there was occupational exposure to wood dust in 10 cases. Wood dust concentrations in the breathing zone, respiratory symptoms and upper airway function were studied in 68 workers in the furniture industry. The dust concentrations affecting 63% of the workers were higher than 5 mg/m3 (TLV). Middle ear inflammation and common colds were more frequent at high dust concentrations, and the number of workers with nasal mucostasis was directly proportional to the wood dust concentration.

Adenocarcinoma↗
PubMed1977

A new well-characterized, purified allergen preparation from timothy pollen. I. Chemical properties.

A purified allergen preparation, Timothy N, from timothy pollen (Phleum pratense) was characterized with respect to chemical properties in comparison with a commercially available crude extract, Timothy O, from the same pollen material. In Timothy N about 94% of the protein and 99% of both hexoses and pentoses were removed during the purification. Timothy N contains a limited number of proteins with molecular weights of about 15,000 and 30,000. A Timothy N solution of 0.010 mg/ml will have an allergenic activity of 1 HEP.

Allergens↗
PubMed1977

The application of the Reaction Rate Analyser LKB 8600 as an automatic coagulometer.

The application of the Reaction Rate Analyser LKB 8600 (RRA) as an automatic coagulometer is described. The RRA was slightly modified without interfering with its function as an enzyme reaction rate analyser. The endpoint of coagulation was recorded when the increase in absorbance exceeded 0.047 at lambda = 340 nm. The coagulation time was monitored by a counter with automatic print-out or by a recorder. The analytical dispersion, s(x)x, ranged between 0.01 and 0.05. Results (x, y) of the determination of the quantity of plasma coagulation factors (II + VII + X) by RRA and manually by visual recording could be expressed by y = 0.93x + 0.04, r = 0.96, n = 66 (method of Owren & Aas) or by y = 1.00x + 0.02, r = 0.98, n = 49 (Normotest). Similarly, plasma activated partial thromboplastin time (Activated Thrombofax) could be expressed by y = 0.99x + 5.00, r = 0.99, n = 23.

Blood Coagulation Tests↗
PubMed1977

Peripheral immunofluorescence of hepatocytes. Relation to smooth muscle antibodies and bile canaliculi.

By means of indirect immunofluorescence microscopy, a peripheral fluorescence reaction with hepatocytes was found, surrounding the entire cell, with sera from patients with cancer and acute hepatitis and from normal blood donors. It was proved that this reaction was not related to bile canaliculi, contrary to bile canaliculi antibody demonstrated previously from patients with chronic active liver disease. By using fluorescein-conjugated anti-human IgG, the reaction with the periphery of the hepatocytes was produced to a more or less pronounced degree with almost all sera studied. The reaction seems not to be directed against contractile proteins on the liver cell membrane as only a minor part of these sera had also IgG smooth-muscle antibody, and anti actomyosin antibody obtained by affinity chromatografy did not react with the hepatocyte. When applying fluorescein-conjugated anti-human IgM the reaction with the periphery of the hepatocytes was observed in one fourth of the patients with acute hepatitis and only sera which contained also IgM smooth-muscle antibody.

Animals↗
PubMed1977

Nickel content of human palatine tonsils: analysis of small tissue samples by flameless atomic absorption spectrophotometry.

We describe a method for determining the nickel content of small tissue samples by flameless atomic absorption spectrophotometry in this case biopsy specimens from human palatine tonsils. Contact between tissue samples and metallic objects was avoided, except for the use of biopsy forceps (Type No. 8150.00 Wolf, stainless steel) for collecting samples, to imitate the actual procedure when small biopsy specimens are removed from the nasal mucosal membranes in nickel workers for histopathological and chemical investigations. Nickel contamination from this instrument was insignificant at the precision of the present procedures. The mean concentration of nickel in 15 tonsils was 13.5 +/- 7.0 (SD) microng/100g (wet wt). The mean nickel concentration in eight different samples of the same tonsil was 5.6 +/- 2.7 (SD microng/100 g.

Adolescent↗