Biomedical subjects

R Pöllänen

Publications and source records attributed to R Pöllänen.

At least 19 recordsLinked to original sources

PubMed2006

Multi-technique characterization of a nuclear bomb particle from the Palomares accident.

A January 1966 accident dispersed Pu and other nuclear bomb materials in the vicinity of Palomares, a village in southeastern Spain. Radioactive particles were identified in a soil sample collected in 1998 and analytical results obtained from one of the isolated particles are presented here. Isolation of the particle was performed using gamma-ray spectrometry and imaging plates. Scanning electron microscopy with X-ray microanalysis revealed the presence of U and Pu as well as Pb and Fe in the particle of approximately 10microm diameter. Radioisotopes of U, Pu, and Am were quantified using radiometric methods, inductively coupled plasma mass spectrometry and secondary ion mass spectrometry. The elevated (235)U/(238)U atom ratio indicates enriched U, and the Pu atom ratios are consistent with weapons-grade material. This work demonstrates that the analysis of individual particles provides information not available through bulk sample analysis.

Mass Spectrometry↗

PubMed2006

High-resolution alpha spectrometry under field conditions - fast identification of alpha particle emitting radionuclides from air samples.

Alpha particle emitting radionuclides may be released into the atmosphere as a result of a severe nuclear accident, the malevolent use of radioactive material or some other incident. Rapid detection methods are then of crucial importance for carrying out well-timed protective actions. The present paper demonstrates that a method in which an aerosol sample is collected on a filter and directly analysed by high-resolution alpha spectrometry in a vacuum chamber, but without radiochemical sample treatment, is suitable for field measurements. A detection limit of less than 0.1 Bqm(-3) for (239)Pu is achieved assuming 1-h sampling using a glass-fibre filter and 1-h data acquisition. This value is higher than in the case when sampling is performed using a porous membrane filter. A measurement system consisting of standard components is mounted in a vehicle designed for rapid field measurements.

Air Pollutants, Radioactive↗

PubMed2006

Minimum detectable activity concentration in direct alpha spectrometry from outdoor air samples: continuous monitoring versus separate sampling and counting.

Rapid method for identifying the presence of alpha particle emitting radionuclides in outdoor air is of paramount importance should a nuclear or radiological incident occur. Minimum detectable activity concentrations of U, U, Pu, and Pu in outdoor air are calculated for two direct alpha spectrometry methods: continuous air monitoring is compared with separate sampling and subsequent alpha particle counting in a vacuum chamber. The radon progeny activity concentration typical for outdoor air and the effects for the alpha particle spectra caused by the properties of the filter and the aerosol particles are taken into account using measurements and Monte Carlo simulations. Continuous air monitoring is a faster method for identifying the presence of (trans)uranium elements when their activity concentration is considerably higher than the typical detection limit. Separate sampling and counting in a vacuum chamber is a more sensitive method when concentrations are close to the detection limit and when the duration of the sampling-counting cycle is greater than approximately 2 h. The method may serve as a tool for rapid field measurements.

Air Pollutants, Radioactive↗

PubMed2005

Design of a radiation surveillance unit for an unmanned aerial vehicle.

This paper describes a prototype of a compact environmental radiation surveillance instrument designed for a Ranger unmanned aerial vehicle. The instrument, which can be used for tracking a radioactive plume, mapping fallout and searching for point sources, consists of three different detector types (GM, NaI(Tl) and CZT) and an air sampling unit. In addition to the standard electronics for data acquisition, the system contains an onboard computer, a GPS receiver and environmental sensors, all enclosed in a single housing manufactured of fiberglass-reinforced composite material. The data collected during the flight is transmitted in real-time to the ground station via a TETRA radio network. The radiation surveillance unit is an independent module and as such can be used in, for example, airplanes, helicopters and cars.

Accidents, Aviation↗

PubMed2004

Simulation of alpha particle spectra from aerosol samples.

A Monte Carlo code is developed for simulating energy spectra of alpha particles from aerosol samples. Geometrical detection efficiency and energy loss of the alpha particles in the source itself and in the material between the source and detector are simulated. Different characteristics of the aerosol particles and medium material are taken into account in the computation. An excellent agreement with earlier results and measurements is found. The code can be applied for example in designing optimal aerosol sampling methods in direct alpha spectrometry.

Aerosols↗

PubMed2003

Characterisation of projectiles composed of depleted uranium.

Projectiles suspected to be composed of depleted uranium (DU) were found in Kosovo. Their properties were analysed using alpha and gamma ray spectrometry, mass spectrometry and electron microscopy. They were found to be composed of DU with small amounts of other elements such as Ti. 236U was detected in the penetrators, reflecting the use of reprocessed fuel. No transuranium elements were detected. The typical external dose rate meter is not the best option for mapping the location of penetrators from the ground. Monte Carlo calculations were performed in estimating possible skin doses. Penetrators in long-lasting contact with skin may cause a notable equivalent dose to skin.

Environmental Exposure↗

PubMed2003

Over-expression of tenascin-C in malignant pleural mesothelioma.

AIMS: Tenascin-C is an extracellular matrix glycoprotein known to have anti-adhesive characteristics and to be expressed in various human malignant neoplasms. We hypothesized that the expression of tenascin-C would be increased in human malignant pleural mesothelioma, and its accumulation associated with the prognosis of the patients with this disease. METHODS AND RESULTS: Thirty-seven cases of mesothelioma were studied by immunohistochemically using a monoclonal antibody against tenascin-C, and with a semiquantitative scoring system for tenascin-C in different areas of the tumours. In 10 selected cases tenascin-C mRNA in-situ hybridization was also analysed. Since transforming growth factor-beta (TGF-beta) is known to induce both the synthesis of tenascin-C and the growth of mesotheliomas, an immunohistochemical analysis of TGF-beta 1, -beta 2 and -beta 3 was also performed. Normal pleura (n = 7) and metastatic pleural adenocarcinomas (n = 7) were used as controls. Tenascin-C protein was expressed in every histological subtype of malignant mesothelioma, being most prominent in the fibrotic stroma of a tumour, around tumour cells and at the invasive border, whereas tenascin-C mRNA was scarce in tumour cells. The patients with less immunohistochemical expression for tenascin-C tended to live longer (P = 0.028 by Fishers' exact probability test). All mesotheliomas showed positivity for at least one isoform of TGF-beta. CONCLUSIONS: In conclusion, high expression of tenascin-C protein in malignant pleural mesotheliomas may play a role in its invasive growth, and might serve as a prognostic marker of the disease.

Adenocarcinoma↗

PubMed2001

Analysis of radioactive particles from the Kola Bay area.

Two types of radioactive particle were identified in marine sediment and lichen samples collected from the Kola Bay, NW Russia. The particles were identified by means of gamma-ray spectrometry and autoradiography, separated and subjected to various analysis techniques. Several complementary techniques are needed to characterise particle properties thoroughly. 137Cs was present in the sediment matrix in large (approximately 100 microns) greenish particles that were most probably pieces of paint. Although their element composition was heterogeneous, 137Cs was found to be evenly distributed. 60Co in the lichen matrix was present in small (approximately 1 micron) particles. No U or transuranium elements were detected in either type of particle.

Autoradiography↗

PubMed2001

Distribution and mRNA expression of tenascin-C in developing human lung.

Tenascin-C is an extracellular matrix glycoprotein that is spatially expressed during organogenesis, in inflammatory and fibrotic disorders, and in neoplasms. The aim of this study was to analyze its expression in developing human lung tissues during pseudoglandular, canalicular, saccular, and alveolar periods corresponding to Weeks 12 to 40. Lung tissues were obtained at autopsy from 34 nonmalformed cases. An immunohistochemical analysis and a messenger RNA (mRNA) in situ hybridization method combined with light microscopy were used. The extent of tenascin-C immunoreactivity was scored as absent, low, moderate, or strong in and around different types of pulmonary cells. The immunohistochemical expression for tenascin-C was strong beneath the airway epithelium, especially at the sites of airway subdivision during Weeks 12 to 23, whereas its expression was moderate or weak underneath alveolar and bronchiolar epithelia between Weeks 24 and 40. The expression for tenascin-C was strong in the intima of veins, especially in the canalicular period, i.e., Weeks 17 to 28. A moderate or strong immunoreactivity for tenascin-C was also observed around chondrocytes in every case studied during all periods. The increased expression of tenascin-C mRNA was most often seen in the cells below the airway epithelium. Taken together, tenascin-C is expressed in human lung during all developmental periods, and its expression is especially strong below the airway epithelium at the sites of airway subdivision.

Gestational Age↗

PubMed2000

Tenascin mRNA expression at the foci of recent injury in usual interstitial pneumonia.

To elucidate which cells are synthesizing tenascin in usual interstitial pneumonia (UIP) we have analyzed thoracoscopic or open lung biopsies from 30 patients with UIP by mRNA in situ hybridization, using (35)S-labeled tenascin RNA probes. The phenotype of the cells expressing tenascin mRNA was confirmed by immunohistochemical stainings of serial sections with antibodies against alpha-smooth muscle actin and human cytokeratin. The results demonstrate that tenascin is expressed at the foci of recent lesions consisting of intralumenal or incorporating loose fibrotic buds. The cells expressing tenascin mRNA were located in and underneath the newly formed epithelium. Immunohistochemical stainings showed that the cells in the newly formed epithelium were strongly cytokeratin positive, and thus evidently regenerating type 2 pneumocytes, while the cells underneath the newly formed epithelium were alpha-smooth muscle actin positive and apparently myofibroblasts. Tenascin mRNA expression was clearly stronger and more frequent in myofibroblasts than in type 2 pneumocytes, however. Weak tenascin mRNA expression was also found in metaplastic bronchiolar-type epithelium and alveolar macrophages. Our results are thus in good agreement with the previous studies showing that tenascin is actively synthesized at the early fibrotic lesions in UIP. Furthermore, results demonstrate that the interaction between the epithelium and the underlying connective tissue plays a significant role in tenascin synthesis and that myofibroblasts are mainly responsible for its synthesis in fibroblastic foci of UIP.

Adult↗

PubMed2000

Tenascin expression and distribution in pleural inflammatory and fibrotic diseases.

We hypothesized that tenascin expression is increased in pleural inflammatory and fibrotic diseases and that its expression can be used as a marker of active pleural involvement. For this purpose we analyzed 71 histological samples of inflammatory and fibrotic pleura from patients with asbestos-induced pleural reaction (n = 6), postcardiac injury syndrome (n = 6), parapneumonic infection and/or empyema (n = 23), tuberculosis (n = 5, rheumatoid disease (n = 1), and fibrosis with inflammation of unknown etiology (n = 30). All 71 cases were studied by immunohistochemistry for tenascin. In 19 selected cases tenascin mRNA in situ hybridization was also performed. In every case, tenascin was increased by immunohistochemistry. Most prominent immunoreactivity was detected in areas of newly formed fibrosis. Increased tenascin mRNA expression by in situ hybridization was detected in the individual cells of the newly formed fibrosis underneath the fibrinous exudate. The tenascin mRNA-positive cells localized in areas in which by immunohistochemical studies the cells were positive for alpha-smooth muscle actin, desmin, and vimentin, suggesting a myofibroblast phenotype. Tenascin mRNA expression was also seen less frequently in areas in which some cells were positive for cytokeratin. These cells might represent mesothelial cells entrapped in the inflammatory lesion. Alternatively, they might represent fibroblast-type cells with aberrant cytokeratin expression. We conclude that in pleural inflammatory and fibrotic diseases tenascin immunoreactivity is increased and tenascin mRNA-positive cells localized mainly in the areas of myofibroblast- and, less often, mesothelial-type cells, suggesting that mainly myofibroblasts and, less commonly, also mesothelial cells might be responsible for tenascin expression in pleural inflammatory and fibrotic diseases. (J Histochem Cytochem 48:1257-1268, 2000)

Aged↗

PubMed1997

Tenascin expression is associated with a chronic inflammatory process in abdominal aortic aneurysms.

PURPOSE: This study was performed to test whether tenascin, a large oligomeric glycoprotein of the extracellular matrix, is present in AAA disease and whether it could play a pathophysiologic role in the development of this disease. METHODS: Tenascin immunoreactivity was investigated from samples of the aneurysmal walls of 17 patients with AAAs, and the results were compared with the results of those of six patients with aortoiliac occlusive disease (AOD) and one normal control patient. To study the source of tenascin mRNA synthesis, some tissue samples were also examined with a tenascin RNA probe by in situ hybridization. RESULTS: The difference in immunoreactivity between the AODs and AAAs was especially prominent in the adventitial layer, where the specimens from AAAs displayed strong diffuse and reticular immunostaining. In AAAs the immunostaining was clearly associated with the degree of mononuclear inflammatory cell infiltrate and with the neovascularization of the adventitial layer. CONCLUSION: Tenascin expression is evident in AAA disease and is distinctly associated with mononuclear inflammatory cells. The adhesive properties of tenascin may offer a relevant explanation for the mechanism by which monocytes transmigrate into the aortic wall. The definitive role of tenascin in AAA process may be more complex, however, and will necessitate further investigation.

Adult↗

PubMed1997

Tenascin expression in lichen sclerosus.

In this study, the distribution of tenascin immunoreactivity in 44 cases of vulvar lichen sclerosus (LS) was investigated. To assess the epithelial basement membrane structure, immunostaining with an antibody to type IV collagen was performed. Ten selected cases were also analyzed by in situ hybridization with a tenascin RNA probe to study the cellular distribution of tenascin mRNA synthesis in LS. Strong tenascin immunoreactivity could be found in LS, especially in areas with subepithelial edema and marked inflammation. By in situ hybridization, signals for tenascin mRNA could be found in basal keratinocytes, dermal fibroblasts, and endothelial cells. Staining for type IV collagen often revealed attenuation and discontinuity in the basement membrane. The abnormal accumulation of tenascin in LS suggests that it may participate in the pathogenesis of this disease. As shown by in situ hybridization, the cell types responsible for tenascin synthesis are basal keratinocytes, dermal fibroblasts, and endothelial cells. Because tenascin, together with fibronectin, is able to upregulate the expression of 92 kDa collagenase and stromelysin in fibroblasts, the matrix destruction and basement membrane damage in LS may partly be a consequence of an abnormal accumulation and synthesis of tenascin. The upregulation of tenascin synthesis in dermal fibroblasts, endothelial cells, and keratinocytes in LS could be mediated by an abnormal expression of growth factors, most notably TGF-beta, which are able to stimulate tenascin synthesis in many non-neoplastic and neoplastic cell lines.

Collagen↗

PubMed1997

Multicellular origin of tenascin in skin tumors--an in situ hybridization study.

Tenascin mRNA expression was studied by an in situ hybridization method in 27 skin tumors. Tenascin synthesis was increased in all skin tumors when compared to uninvolved skin but there was variation in the site of cellular synthesis between different types of tumors. In melanocytic nevi and precancerous keratinocyte lesions, tenascin seemed to be of epidermal or stromal origin. In basal cell carcinoma, squamous cell carcinoma and malignant melanoma, there was tenascin synthesis also in tumor cells. These findings are in concordance with earlier studies which suggest a role of tenascin as an anti-adhesive and motility-promoting factor in malignant skin tumors.

Basal Cell Carcinoma↗

PubMed1996

The association of vascular proliferation with HPV status and epithelial PCNA positivity in cervical intraepithelial lesions.

In this study we investigated the number of blood vessels and vascular proliferation in subepithelial areas of 80 cervical condylomas and cervical intraepithelial neoplasias (CIN). The number of blood vessels was determined by counting factor VIIIRAg-positive vascular channels in areas beneath the epithelial lesions. Vascular proliferation was evaluated by determining the number of proliferating cell nuclear antigen (PCNA)-positive endothelial cells in the subepithelial connective tissues. The results were compared with the expression of human papillomavirus (HPV) DNA subgroups (6/11 (low-risk) and 16/18/31/33/35 (high-risk) of the lesions, as determined by dot-blot and in situ hybridization, and with epithelial cell proliferation as determined by immunohistochemistry for PCNA. Also p53 immunohistochemistry of the lesions was performed. Even though CIN II-III lesions on average contained more factor VIIIRAg-positive blood vessels compared to condylomas and CIN I lesions, no significant association was found between their number and the degree of dysplasia. However, moderate or strong PCNA staining in vascular endothelial cells was seen significantly more often in CIN II-III lesions than in condylomas and CIN I lesions (p = 0.008): 34/80 (45%) cases contained detectable HPV DNA as determined by dot-blot or in situ hybridization. There was no correlation between the presence or absence of HPV DNA and the number of PCNA-positive endothelial cells. Nine cases showed p53-positive cell nuclei and in three cases there was more than 1% positive nuclei in the lesion. No association was found between the vascularity or the number of PCNA-positive endothelial cells and the p53 immunoreactivity. The increased proliferative activity of endothelial cells in CIN II-III lesions suggests that they are angiogenically more active than condylomas and CIN I lesions. This activity does not, however, depend on the HPV or p53 status. This is the first report in which endothelial cell PCNA positivity was used as a marker for vascular proliferation.

Antigens, Neoplasm↗

PubMed1996

Tenascin in human papillomavirus associated lesions of the uterine cervix.

The immunohistochemical expression of tenascin was studied in 80 morphologically diagnosed condylomas and cervical intraepithelial neoplasia (CIN) lesions. The results were compared with the human papillomavirus (HPV) DNA subtype, which was determined by HPV dot blot and in situ hybridisation. Tenascin mRNA synthesis was also determined in 10 selected cases by in situ hybridisation. No statistically significant association was found between tenascin expression and the degree of dysplasia or the HPV subtype. There was, however, a strong correlation between the extent of tenascin immunoreactivity and the degree of inflammation. Synthesis of tenascin mRNA was detected in basal keratinocytes and in fibroblasts by in situ hybridisation. The lack of association between the grade of CIN and tenascin expression precludes its use as a marker of premalignancy in CIN.

Base Sequence↗

PubMed1996

Presence of human papillomavirus DNA and abnormal p53 protein accumulation in lung carcinoma.

BACKGROUND: In some carcinomas inactivation of the tumour suppressor gene product p53, either by point mutation or indirectly by the human papillomavirus (HPV), has been suggested as two alternative routes to malignant transformation. To test this hypothesis in lung tumours, 43 lung carcinomas were analysed by in situ hybridisation and polymerase chain reaction (PCR) for the presence of HPV DNA, and the results were compared with p53 protein immunohistochemical analysis. METHODS: The presence of HPV DNA in lung carcinoma was detected by nucleic acid in situ hybridisation for HPV types 6, 11, 16, 18, 31, and 33 using nonradioactively labelled DNA probes. Polymerase chain reaction (PCR) analysis was performed on all cases showing positive HPV DNA labelling by in situ hybridisation and in an additional 13 negative cases. Abnormal nuclear accumulation of the p53 protein was revealed by immunohistochemistry using the avidin-biotin-peroxidase complex method and a CM-1 polyclonal anti-human p53 antibody and a monoclonal mutation-specific Pab 240 p53 antibody. RESULTS: HPV DNA was found by in situ hybridisation in 13 lung carcinomas (30%). In all these cases subtype-specific HPV DNA could also be detected by PCR. Abnormal p53 protein accumulation was seen in 21 of the 43 carcinomas (49%), of which 18 were HPV negative. Twelve (57%) of the CM-1 positive cases were also positive for the mutation-specific antibody Pab 240. There was an obvious inverse relationship between the presence of papilloma viral DNA and abnormal p53 protein accumulation. CONCLUSIONS: p53 plays an important part in the development of lung carcinomas and, in some cases, HPV may contribute to it by binding and inactivating the p53 protein.

Adenocarcinoma↗

PubMed1995

p53 protein accumulation and the presence of human papillomavirus DNA in bronchiolo-alveolar carcinoma correlate with poor prognosis.

Accumulation of the tumour suppressor gene p53 product due to a gene mutation is frequently seen in human carcinomas, including lung carcinoma. Another indirect mechanism involving p53 in malignant growth relates to the E6 protein of the human papillomavirus (HPV), which is able to bind and degrade wild-type p53 protein, thus eliminating its tumour suppressor activities. Bronchiolo-alveolar carcinoma (BAC) is a rare type of lung carcinoma. The aim of our study was to examine the occurrence of p53 accumulation and the presence of HPV DNA in BAC. Sections of 22 BACs were immunohistochemically stained using a p53 antibody, CM-1. The presence of HPV DNA in BACs was verified by in situ hybridisation for HPV types 6, 11, 16, 18, 31 and 33 and confirmed by PCR. Thirty-six percent of the tumours showed abnormal p53 nuclear accumulation, and HPV DNA, revealed by in situ hybridisation, was found in 36%. Unexpectedly, only 13% of the type 1 BACs were positive for p53, whereas 45% of the type 2 BACs were positive. During a follow-up of 12-176 months, only 10% of the patients with BACs negative for both p53 and HPV died of the disease, compared with 42% of the patients with either p53 or HPV positivity. No inverse relationship between abnormal p53 protein accumulation and the presence of HPV DNA was found.

Adenocarcinoma, Bronchiolo-Alveolar↗