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Biomedical subjects

O Nielsen

Publications and source records attributed to O Nielsen.

At least 91 records · Page 5Linked to original sources
PubMed1983

Tracing the use of torture: electrically induced calcification of collagen in pig skin.

Reports of the use of electrical torture are usually denied, so that there is an urgent need of diagnostic methods to distinguish the consequences of electrical torture from other superficial injuries. The 'electrical group' of Anti-Torture Research (ATR) has accordingly studied the possibility of distinguishing between the sequelae of electrical and heat injury. Among the reported differences of the two types of injuries is the occurrence in epidermis, vessel walls and sweat glands of vesicular nuclei exclusively in electrically injured skin. On the basis of experiments with anaesthetized pigs, we now report that the late sequelae of electrical injury appear to include the deposition of calcium salts beneath the area of an electrical cathode.

Aggression↗
PubMed1983

The effect of direct current, sodium hydroxide and hydrochloric acid on pig epidermis. A light microscopic and electron microscopic study.

Lesions in pig skin were induced by direct current, hydrochloric acid and sodium hydroxide, and the morphology of the lesions was compared in order to establish the influence of electrolysis in the electrical lesions. Both light microscopically and electron microscopically a pronounced similarity was found between cathode lesions and base-induced lesions including the presence of vesicular nuclei in both kinds of lesions. Some features were also common to anode lesions and acid induced lesions, but dissimilarities were present as well. From the results it is concluded that electrolysis in the tissue with the subsequent shift of pH, especially towards the alkaline side, is responsible for the formation of the vesicular nuclei which we repeatedly have found to be characteristic of electrical skin lesions. The shift of pH also induces the cytoplasmic feature called "white necrosis" which therefore is found more regularly in electrical lesions than in heat lesions.

Animals↗
PubMed1983

Epidermal changes in heat and electrically injured pig skin. A light microscopic study of the influence of heat energy intensity and electrical current frequency.

Pigs were exposed to heat of low and high temperature and electricity of various frequences. Comparable amounts of energy were transferred in all experiments. In lesions induced by heat of low temperature granularity and/or fibrillarity of the cytoplasm were present in the epidermal cells. Lesions induced by heat of high temperature had a similar appearance, but occasionally "white necrosis", defects in the epithelium and light yellow material in stratum corneum were present. Lesions induced by 100.000 hz alternating current were segmental but otherwise microscopically often indistinguishable from lesions produced via transfer of heat of low temperature. Lesions induced by 8000 hz and 59 hz alternating current were segmental. Vesicular nuclei, "white necrosis" and yellow, clumped keratin were present in most lesions. Anode areas in direct current induced lesions showed a shrunken epidermis. The cytoplasm of the epidermal cells were often eosinophilic and homogeneous, and the nuclei were small with condensed chromatin. Occasionally, "empty" nuclei were noted. Yellow, clumped keratin was presented in all lesions. In cathode areas epidermis was of varying thickness and "white necrosis" and vesicular nuclei were present. The pathogenesis of the individual morphological features is discussed based upon theoretical concepts and the difference in morphology of the various lesions encountered in the present study as well as in other studies in this series of experiments. It is concluded that except for lesions produced via transfer of high frequency alternating current the morphology of electrical lesions is specific. Further, an alleged torture instrument was able to produce lesions similar to those observed in the experimental studies.

Animals↗
PubMed1982

Flow sorting of mouse pancreatic B cells by forward and orthogonal light scattering.

Mouse islet cell suspensions were separated into subpopulations based on forward low angle and orthogonal scattered light. Separation fractions were analyzed for hormone content by radioimmunoassays. The pancreatic B-cells had the highest orthogonal light scattering, while they overlapped in forward low angle light scattering with other endocrine (glucagon, pancreatic polypeptide and somatostatin containing cells) and nonendocrine cells. Living and paraformaldehyde fixed islet cell suspensions showed similar distributions of combined light scattering.

Animals↗
PubMed1982

Epidermal changes in heat and electrically injured pig skin: a light microscopic study of the sequences in morphology.

Biopsies were obtained from heat and electrically exposed pig skin at different at different times after exposure, in order to describe the morphological sequences in heat and electrically injured skin. The work is part of a series of studies in which it is investigated whether morphological methods can be used in disclosing electrical torture. Epidermal changes in heat lesions differed from those of electrical lesions in all experiments. Heat lesions typically showed a detached epidermis with fibrillar or granular cytoplasm. In older lesions the epidermis appeared concrete. Electrical lesions showed an attached epidermis with small defects, a white, homogeneous cytoplasm, vesicular nuclei and curled, clumped keratin. The electrical lesions were rejected at day 4 or 5. The number of characteristic morphological changes in epidermis decreased with the age of the lesions. It is concluded that epidermal electrical lesions differ in morphology from heat lesions and that it is possible to evaluate the age of the lesions.

Animals↗
PubMed1981

Islet transplantation in mice differing in the I and S subregions of the H-2 complex.

Diabetic A.TL and A.TH mice, congenic inbred strains differing only in the I and S (non-K, non-D) regions of the major histocompatibility (H-2) complex, received intrasplenic allogeneic and isogeneic pancreatic islet transplants. The isografts were uniformly accepted, while approximately 60% of the recipients receiving allografts rejected the islets, most within 4 weeks of transplantation. With either strain the animals accepting the allografts had higher blood glucose values than normal mice or isografted recipients. After a minimum of 13 weeks of nearly normal glucose levels, successfully allografted mice received skin grafts and spleen cells. None of the A.TH recipients rejected the A.TL islets, but two of four A.TL recipients of A.TH islets became diabetic after the skin grafts. These observations suggest a variable response to islet transplanted across this isolated difference of the H-2 complex. Furthermore, allografted islets resisting rejection did not provide normal glucose levels in the recipients.

Animals↗
PubMed1979

Flowcytometric evaluation of the DNA distribution in isolated pancreatic islets from normal and diabetic mice.

Pancreatic islets from C57BL/KsJ-db/db, and +/+ mice were isolated by collagenase. After isolation the islets were transferred to a hypotonic ethidiumbromide solution with 0.3% of the detergent Nonidet P40. After vortexing, the samples were analyzed in a BioPhysics Cytofluorograf 4802A. The DNA histograms were divided into 2c, 2-4c, 4c and 8c fractions under the assumption of a constant rate of DNA synthesis during the 2-4c phase. In comparison with normal mice, we found that diabetic mice had a lower fraction of 2c nuclei and a higher fraction of 2-4c, 4c, and 8c nuclei. These results obtained by flow cytometry are in agreement with results obtained by 3HTdR incorporation and by cytophotometry on histological sections.

Animals↗
PubMed1978

Sequential cold-sensitive mutations in Aspergillus fumigatus.

Mutants of thermotolerant fungus Aspergillus fumigatus I-21 (ATCC 32722) unable to grow at 37 degrees C were sought. Cold-sensitive mutants were enriched from progeny spores of gamma-irradiated conidia by two or more incubations at various nonpermissive temperatures alternating with filtrations through chessecloth. The approximate minimum, optimum, and maximum growth temperatures of the parent were 12, 40, and 50 degrees C, respectively. Mutants unable to grow at 37 degrees C were not successfully isolated directly from the wild type. A mutant unable to grow at 25 degrees C was isolated and mutations further increasing the cold sensitivity by increments of 3-5 degrees C were found to occur. Mutants completely unable to grow at 37 degrees C were obtained by five sequential mutations. All mutants grew as fast as the wild-type parent at 45 degrees C and higher. Each mutant produced revertants able to grow not only at the nonpermissive temperature used for its isolation but also at lower temperatures.

Aspergillus fumigatus↗
PubMed1976

Umbilical vein catheterization and portal hypertension.

Portal hypertension is a rarely encountered late complication of umbilical vein catheterization. A survey of the 38 cases previously published is presented together with an additional case report. It is concluded that catheterization for more than 2 days carries an increased risk of thrombosis, and that umbilical artery catheterization should be preferred in the majority of cases due to a reduced risk of complications. The correct position of the catheter tip must always be controlled by fluoroscopy or X-ray. Infusion of hypertonic solutions with unphysiological pH should be restricted and umbilical vessel catheterization should only be carried out in severe cases. Pretreatment of the catheters with heparin possibly reduces the hazards.

Catheterization↗
PubMedDate not supplied

Electrical and thermal injuries in pig skin--evaluated and compared by light microscopy.

The morphology of pig skin after electrical (el) and thermal exposure was studied in order to find methods applicable for disclosing electrical torture. Biopsies from pig skin exposed 24 hours earlier to either heat or electrical current under general anesthesia were studied by light microscopy. The amount of energy used of either type ranged from about 6 to about 100 joule deposited on two circular areas of the skin measuring 12 mm in diameter. In sections stained with hematoxylin and eosin alterations were found in heat-influenced specimens following the administration of moderate and large doses of energy. Changes were observed in el-influenced specimens also after the administration of low amounts of energy, which did not lead to macroscopical changes in the skin. The two types of energy induced different patterns of alterations inside the epidermis. The most characteristic change following heat exposure was the presence of a granular or fibrillar eosinophilic cytoplasm and subepidermal clefts, while el-expoure often produced white homogeneous cytoplasm and shadowy nuclei ("white necrosis") in the attached epidermis. The individual changes could be produced by both types of injury, but to a highly different degree. However, the alteration classified as "vesicular nuclei" was only observed observed in el-damaged skin. The dermis from the more severely injured skin of both groups showed a homogeneous appearance ("necrosis"). While the changes of epidermis and dermis in response to heat were diffusely distributed, the changes created by electrical injury were often present in segments. By electrical damage homogeneous areas with loss of stainability and shadowy nuclei were occasionally observed in sweat glands, hair sheaths and in vessel walls, structures which are suggested to serve as conductors for the electrical current. "Vesicular nuclei" were observed in similar structures. Some of the findings may be associated with differences in intensity of energy during exposure to heat and electricity. Furthermore, the existence of different biological patterns following the two types of exposure should be considered. The studies are being continued to elucidate these basic questions, and to study further the medical diagnostic potential of examining skin biopsies from tortured individuals.

Animals↗
PubMedDate not supplied

Early epidermal changes in heat- and electrically injured pig skin. I. A light microscopic study.

In order to find methods applicable for disclosing electrical torture, pig skin was exposed to heat and electricity under controlled circumstances. Biopsies were obtained immediately after exposure and the morphology of the heat lesions was compared to that of electrical lesions. The cytoplasm of epidermal cells in heat lesions appeared granular or fibrillar, while the nuclei were rather unaffected. In electrical lesions the cytoplasm appeared homogeneous often with a peculiar white colour in hematoxylin-eosin stained sections. The nuclei were either dark and shadowy or enlarged and vesicular. The keratin in electrical lesions often showed a bright yellow colour. Small defects in the epidermis were seen in some electrical lesions. Thus the morphology of electrical lesions differed markedly from that of heat lesions. Although some of these differences may be due to differences in distribution and intensity of energy, it is probable that pH shifts in the cells due to electrolysis is the main cause of the specific morphology of electrical lesions.

Animals↗
PubMedDate not supplied

Early epidermal changes in heat- and electrically injured pig skin. II. An electron microscopic study.

In order to find methods applicable for disclosing electrical torture, pig skin was exposed to heat and electricity under controlled circumstances. Biopsies for electron microscopy were obtained immediately after exposure. In heat lesions the nuclei were slightly distorted, sometimes with broken nuclear membranes. The tonofilaments were clumped, intracellular oedema was present and cell membranes were ruptured between desmosomes. In electrical lesions the nuclei were usually enlarged with strongly condensed chromatin. Some nuclei were composed of fine, evenly dispersed granular material. The cytoplasm appeared homogeneous, in large magnification finely granular. Cell borders could sometimes be identified located in situ. In the stratum corneum, which appeared normal in heat lesions, single or several cells or large areas had an electron-dense appearance. The difference in ultrastructure of heat and electrical lesions makes it probable that electricity has a specific action on epidermal cells.

Animals↗