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Biomedical subjects

M Petersen

Publications and source records attributed to M Petersen.

At least 19 recordsLinked to original sources
PubMed1992

A comparison of radiographic interpretation of silica exposed workers using the 1963 and the 1986 Chinese roentgenodiagnostic criteria of pneumoconioses.

As part of a larger study relating to silica exposure, silicosis, and lung cancer mortality in Chinese mine and factory workers, 1936 old posterior-anterior chest X-rays were re-interpreted according to the 1986 Chinese Roentgenodiagnostic Criteria of pneumoconioses. Each film was independently read by three individuals from a panel of eleven radiologists, and this reading was compared to the original one. Subsequent to the independent readings, a groups of three readers interpreted the films together, called the consensus readings. Comparisons were made by Chinese stage of pneumoconiosis. For the entire cohort, there was a crude agreement of 57.4% between the old and the new interpretations. Agreement within one step of full agreement was 92.5%. The interpretations done by median reading and by consensus were very similar. In general, there was a tendency for the old readings to be slightly higher compared to the new interpretations. This tendency was most marked in the tin mines, followed in decreasing order by the iron/copper mines, the potteries, and the tungsten mines. The agreement between the old and new interpretations is felt to be satisfactory.

Humans↗
PubMed1992

Nursing caries in Head Start children, St. Thomas U.S. Virgin Islands: assessed by examiners with different dental backgrounds.

The purposes of this study were to determine the prevalence of nursing caries in 3- to 5-year-old Head Start (HS) children on St. Thomas, U.S. Virgin Islands and to assess the reliability of examiners with different dental backgrounds. A dentist, hygienist, and nondental HS personnel participated in a 1/2 day training session (lecture and workshop) and then independently conducted visual examinations for caries of the maxillary anterior teeth including nursing caries. Twenty-three HS personnel examined a total of 375 children; the dentist and hygienist examined a random sample of 74 and 73 children, respectively. Seventy-one children received all three independent examinations. Reliability was assessed by percent agreement, sensitivity, specificity, and kappa value. The dentist found 41% of the children had caries of the maxillary incisors, which included nursing caries. The percentage of children with nursing caries was 12%. There was strong-to-good diagnostic agreement between the dentist and hygienist. The HS personnel also found that 12% of the children had nursing caries, but the diagnostic agreement between the dentist and HS personnel was only good-to-fair.

Bottle Feeding↗
PubMed1991

Relationships between capsaicin sensitivity of mammalian sensory neurons, cell size and type of voltage gated Ca-currents.

(1) The relationships between capsaicin sensitivity, cell size and the expression of voltage-dependent high-threshold (L- and N-type) and low-threshold (T-type) Ca-currents were investigated in cultured adult rat dorsal root ganglion neurons using the whole-cell patch-clamp technique. (2) The capsaicin (10 microM) evoked inward current was used to identify the capsaicin-sensitive population. To identify the voltage-dependent Ca-currents, the activation threshold and the inactivation kinetic were used. (3) In cultured dorsal root ganglion cells the capsaicin sensitivity is not restricted to the small cell population. About 28% of cells with large cross sectional areas (greater than or equal to 1001 microns 2) responded with about the same amplitude per micron2 cross sectional area as small cells. (4) The amplitude of the capsaicin evoked inward current depended on the length of time the cells were maintained in culture. (5) All cells exhibited the high-threshold Ca-currents. About 45% of the capsaicin-insensitive cells also had low-threshold Ca-currents. None of the capsaicin-sensitive cells had the low-threshold type. (6) Most of the cells which expressed the low-threshold type were in the upper size range.

Animals↗
PubMed1990

Antibody production and tissue irritation in swine vaccinated with Actinobacillus bacterins containing various adjuvants.

The effects that Actinobacillus pleuropneumoniae bacterins containing paraffin (mineral) oil, Al(OH)3, or lecithin-base oil adjuvants had on antibody production and muscle irritation were studied. Four hundred and thirty-two pigs were vaccinated twice (864 injection sites) at a 30-day interval. To assess effects of skin surface contamination on tissue reaction, 247 of the injections were made through skin soiled with manure. Serum samples for antibody determination and tissue samples were obtained at slaughter (15 to 90 days after vaccination). Bacterins containing Al(OH)3 or 5% lecithin-base oil as an adjuvant resulted in minimal tissue irritation. Bacterins containing paraffin oil or greater than 20% lecithin-base oil were more irritating to muscle, often resulting in a granuloma or an abscess at the injection site. Pigs given bacterins containing Al(OH)3 adjuvant had lower antibody titers than did pigs given bacterins containing paraffin oil or lecithin-base oil adjuvants.

Actinobacillus↗
PubMed1990

A family study of atopic dermatitis. Clinical and genetic characteristics of 188 patients and 2,151 family members.

The history of 188 caucasian patients with atopic dermatitis (AD) and of 2,151 family members has been analyzed. Of the AD patients 48% suffered from respiratory atopy (36% rhinitis, 28% asthma, and 15% both). AD showed by far the earliest onset of all atopic diseases: 50% of our patients had skin lesions before the age of 2 years and 60% before the age of 5 years. In contrast, symptoms of allergic asthma developed in 40% of AD patients before the age of 5 years in comparison with only 25% who had allergic rhinitis. AD affects females more frequently than males (male to female ratio 1:1.5), regardless of whether additional respiratory atopies are present or not. In contrast, respiratory atopies develop more frequently in males than in females (male to female ratio 1.5:1). Mothers with respiratory atopy more often have atopic children (26%) than do fathers with respiratory atopy (13%). Finally, risk figures for genetic counselling are given. In short, the general risk of developing AD (3%) and atopy (7%) increases by a factor of two with each first-degree family member already suffering from atopy.

Adolescent↗
PubMed1990

Observations of the use of o-phthalaldehyde condensation for the measurement of histamine.

The in vitro study of mast cell degranulation utilises the measurement of histamine as a quantitative marker of this process. Histamine is most commonly assayed, following organic extraction, by condensing it with o-phthalaldehyde (OPT) and thereby obtaining a highly fluorescent adduct. A number of variables that might affect the performance of this assay, including assay conditions, stability and purity, were evaluated during the course of developing this assay for use in our laboratory. We observed the stability of OPT-histamine and found it to be very stable at 0 and 25 degrees C, following acidification. Derivatisation conditions and the purity of the leukocyte histamine extract were also assessed, and indicated that derivatisation at low temperatures slows down decay, providing a greater over-all fluorescence intensity. Extraction procedures are necessary, prior to condensation with OPT, to eliminate both positive and negative interfering substances from leukocyte preparations.

Histamine↗
PubMed1990

Zymosan-induced leukotriene B4 generation by human neutrophils is augmented by rhTNF-alpha but not chemotactic peptide.

Tumour necrosis factor (TNF) is a mediator of inflammation that has been shown to enhance neutrophil responses to soluble and particulate stimuli. The release of leukotriene B4 (LTB4) by human neutrophils stimulated by unopsonized zymosan was measured in the presence or absence of recombinant human TNF-alpha (rhTNF-alpha) preincubation. There was a threefold increase in the LTB4 response at an optimal TNF concentration of 10(-9) M and an optimal preincubation time of 10-20 min. A similar time and dose dependency was observed for CR3 receptor expression and for the release of the secondary lysosomal granule marker, vitamin B12-binding protein. In contrast, the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP), although stimulating an increase in both CR3 receptor number and in particle phagocytosis, failed to induce an increase in LTB4 release in response to zymosan. In addition, the present study demonstrated that, unlike FMLP, the exocytotic mechanism for secondary granule release by rhTNF-alpha functioned in the absence of a rise in cytosolic free calcium. Furthermore, it was independent of changes in cyclic nucleotide concentrations and did not require an intact cytoskeleton. Thus the capacity of rhTNF-alpha to amplify the neutrophil response to zymosan through the CR3 receptor appears to be related to the amplification of post-membrane events as well as to an increase in the number of functionally active receptors.

Antigens, CD↗
PubMed1990

Radionuclide detection of primary pulmonary osteogenic sarcoma: a case report and review of the literature.

A healthy elderly white man was admitted for right inguinal herniorrhaphy. Preoperative chest x-ray revealed a large mass in the lower lobe of the left lung. CT-directed needle biopsy was nondiagnostic. Technetium-99m methylene diphosphonate (99mTc-MDP) bone scan revealed intense soft-tissue activity in the lower left hemithorax with no evidence of abnormal activity in the osseous skeleton. Because of the degree of uptake in the lesion, a presumptive diagnosis of extraosseous osteogenic sarcoma was made. The patient had a left lower lobectomy and the lesion was diagnosed as an osteosarcoma of primary pulmonary origin.

Aged↗
PubMed1989

Effects of quinoline and 8-hydroxyquinoline on mouse bone marrow erythrocytes as measured by the micronucleus assay.

Both quinoline and 8-hydroxyquinoline (HOQ) were tested for their genotoxicity in CD1 male mice by using a bone marrow micronucleus assay. Mice were intraperitoneally treated in single injections with three dose levels (25, 50, and 100 mg/kg) of each chemical with corn oil as solvent vehicle. Bone marrow was sampled at 24, 48, and 72 h postinjection. Quinoline resulted in a significant dose-related increase in the number of micronucleated polychromatic erythrocytes (MPCE) at the 24 h sampling time for all doses tested. The high dose (100 mg/kg) and the medium dose (50 mg/kg) also induced statistically significant increases (P less than .05) in the number of MPCEs at 48 h interval. The ratios of polychromatic to normochromatic erythrocytes at the 24 h sampling time were lower for the treated than the control animals. Although HOQ resulted in some increases in the number of MPCEs over the control, this compound induced a statistically significant increase in the number of micronucleated normochromatic erythrocytes (MNCEs) at all three doses following 24 h treatment. Both low and medium doses also induced a higher incidence of MNCEs at the 48 and 72 h sampling times. No data were available for the high dose at these times. The cytotoxic effect of this compound was expressed as low PCE/NCE ratios with all doses at 24 h after injection and as a high mortality rate in animals treated with the high dose (100 mg/kg).

Animals↗
PubMed1989

Sister-chromatid exchange studies on direct- and indirect-acting clastogens in mouse primary cell cultures.

An in vitro sister-chromatid exchange (SCE) assay using mouse primary bone marrow and spleen cells was conducted with both direct- and indirect-acting genotoxic agents. 2,4,7-Trinitrofluorenone, a direct-acting genotoxic agent, induced a significant dose-related increase in SCEs. In both bone marrow and spleen cells, 2.0 micrograms/ml caused an approx. 3-fold increase in SCE level over control values. Cyclophosphamide, an indirect-acting genotoxicant which requires metabolic activation for its clastogenicity, induced a significant increase in SCEs in the presence of S9 from liver of rats pretreated with Aroclor-1254. A dose of 2 micrograms/ml resulted in a 2-fold increase in bone marrow and a greater than 5-fold increase in spleen cells. Benzo[a]pyrene, another indirect-acting genotoxicant, also induced significant dose-related SCE responses in both cell types. It seems that primary bone marrow and spleen cell culture systems can detect both direct- and indirect-acting genotoxicants and may be useful for routine and/or comparative cytogenetic studies.

Animals↗
PubMed1988

Reconstitution of cytochrome P-450-dependent digitoxin 12 beta-hydroxylase from cell cultures of foxglove (Digitalis lanata EHRH.).

Cytochrome P-450-dependent digitoxin 12 beta-hydroxylase from cell cultures of foxglove (Digitalis lanata) was solubilized from microsomal membranes with CHAPS (3-[(3-cholamidopropyl)dimethylammonio]propane-1-sulphonic acid). Cytochrome P-450 was separated from NADPH: cytochrome c (P-450) reductase by ion-exchange chromatography on DEAE-Sephacel. NADPH:cytochrome c (P-450) reductase was further purified by affinity chromatography on 2',5'-ADP-Sepharose 4B. This procedure resulted in a 248-fold purification of the enzyme; on SDS/polyacrylamide-gel electrophoresis after silver staining, only one band, corresponding to a molecular mass of 80 kDa, was present. The digitoxin 12 beta-hydroxylase activity could be reconstituted by incubating partially purified cytochrome P-450 and NADPH:cytochrome c (P-450) reductase together with naturally occurring microsomal lipids and flavin nucleotides. This procedure yielded about 10% of the original amount of digitoxin 12 beta-hydroxylase.

Cells, Cultured↗
PubMed1988

In vivo and in vivo/in vitro kinetics of cyclophosphamide-induced sister-chromatid exchanges in mouse bone marrow and spleen cells.

In several acute and chronic exposures to various chemicals in vivo and in vitro, the average sister-chromatid exchange (SCE) frequencies in human, mouse, rat, and rabbit lymphocytes generally decrease with time following treatment. The rate of this decline varies, but little data have been published pertaining to the comparative kinetics of SCEs both in vivo and in vivo/in vitro (exposure of animals to the test compound and culturing of cells) simultaneously in the same tissues. In this study, a single dose of cyclophosphamide (40 mg/kg) was injected for varying periods (6-48 h) and its effects, as assessed by the induction of SCEs, were analyzed under both in vivo and in vivo/in vitro conditions in mouse bone marrow and spleen cells. In vivo, the cyclophosphamide-induced SCEs increased with increasing time up to 12 h, stayed at approximately the same level until 24 h, and then decreased with increase in post-exposure time. However, the SCE levels remained significantly higher than controls at 48 h post-exposure time in both bone marrow and spleen cells. Under in vivo/in vitro conditions, the SCEs in bone marrow decreased with increase in post-exposure time until reaching control values by 48 h post exposure. However, in spleen cells, the decrease in SCE level was gradual, and by 48 h post-exposure time, the cells still had approximately 6 times higher SCEs than the control values. These results suggest that there are pharmacokinetic differences for cyclophosphamide in mouse bone marrow and spleen. Also, there is a differential SCE response to cyclophosphamide under in vivo and in vivo/in vitro conditions.

Animals↗
PubMed1988

Sister-chromatid exchanges induced by triethylenemelamine: in vivo and in vivo/in vitro studies in mouse and Chinese hamster bone marrow and spleen cells.

This study was designed to obtain sister-chromatid exchange (SCE) frequencies in bone marrow and spleen cells of mice and Chinese hamsters under in vivo and in vivo/in vitro systems following treatment of animals with varying doses (15-405 micrograms/kg) of triethylenemelamine (TEM). A dose-related SCE response was found in both species, tissues, and systems analyzed following TEM treatment. In vivo, similar responses were noted for both tissues in both species. However, in vivo/in vitro, the response was lower than in vivo and it varied with the tissue. The spleen cells were more sensitive and gave higher numbers of SCEs than bone marrow of both species at the two highest doses tested (135 and 405 micrograms/kg). These differences may be attributed to cell-culturing effects, type of cells analyzed, species and tissue specificities, and pharmacokinetic properties of the chemical. This study lends support to recently established in vivo/in vitro cell culture methodologies employing mice and Chinese hamsters for comparative cytogenetic analysis.

Animals↗
PubMed1987

Sympathetic skin response in diabetic neuropathy.

The sympathetic skin response (SSR) was studied in 47 diabetic patients selected for the presence of symptoms and clinical signs of peripheral neuropathy and in 24 normal control subjects. The SSR was present in all controls but was absent at the foot in 66% and at the hand in 27.7% of the diabetic patients. Absence of the SSR failed to correlate with other electrophysiologic parameters on routine nerve conduction and electromyographic studies. Although absent SSR was more often found in patients with symptoms of autonomic dysfunction (P less than 0.05), there was no correlation with any specific symptoms of autonomic involvement. The SSR was frequently absent, at least in the foot, in those patients with abnormal cardiac beat-to-beat variability (expiratory: inspiratory, E:I, ratio) and pupil cycle time (PCT). In addition there was a good correlation between the amplitude of the SSR and the value of the E:I ratio (r = 0.81, P less than 0.001). The SSR may be a valuable adjunct in the assessment of autonomic involvement in diabetic neuropathy, but its sensitivity requires further evaluation.

Adult↗
PubMed1987

Cyclophosphamide-induced cytogenetic effects in mouse bone marrow and spleen cells in in vivo and in vivo/in vitro assays.

Sister chromatid exchange (SCE) and chromosomal aberration studies have been used to monitor human populations for genotoxic exposure to chemical substances. These monitoring techniques involve collection of blood and/or bone marrow from the exposed subjects and culturing cells for one or two cell cycles with various treatments in culture. The results obtained from such in vivo/in vitro studies may lead to an over- or underestimation of the damage that could occur in vivo. In the present study, which uses a mouse model, the in vivo/in vitro cytogenetic assays (SCEs and chromosomal aberrations) have been compared with similar in vivo systems in bone marrow and spleen cells treated with various doses of cyclophosphamide (CPA). The results indicate a significant difference in CPA-induced cytogenetic endpoints between in vivo and in vivo/in vitro conditions in both organs. However, linear relationships were found between CPA dose and cytogenetic end point analyzed under both conditions. Based on these results it appears that the in vivo/in vitro assay is a useful technique for indicating potential in vivo damage of chemicals.

Animals↗
PubMed1987

The influence of capsaicin on membrane currents in dorsal root ganglion neurones of guinea-pig and chicken.

The effect of capsaicin on voltage-dependent membrane currents of isolated dorsal root ganglia (DRG) neurones of guinea-pig and chicken were investigated by the voltage-clamp technique and intracellular perfusion. In both species, administration of capsaicin (3 X 10(-5) M) to the outer surface of the cell membrane reduced the amplitude and accelerated the inactivation of the fast inactivating potassium current. In contrast, 3,4-diaminopyridine (3,4-DAP) reduced the fast potassium current without affecting the inactivation. Combined application of capsaicin and 3,4-DAP was more effective than either drug alone. The slow potassium current was diminished by capsaicin but not affected by 3,4-DAP. Capsaicin (3 X 10(-5) M) applied to the internal surface of the membrane had little effect on the fast outward current but primarily decreased the amplitude of the slow potassium current. Two subpopulations of sodium currents could be demonstrated in guinea-pig neurones according to their tetrodotoxin (TTX) sensitivity. In type I neurones the sodium current was completely blocked by TTX; type II neurones exhibited a TTX-sensitive as well as a TTX-resistant inward current. Capsaicin (3 X 10(-5) M) applied externally reduced the maximal amplitude of both current components. The time course of inactivation was delayed only in the TTX-resistant sodium current. The effect of capsaicin on Na-currents of DRG neurones was similar in guinea-pigs and chicken. In DRG neurones of chicken, only TTX-sensitive currents were observed. In both species the steady-state inactivation of the sodium currents was shifted by capsaicin to more negative potentials.

Animals↗