Biomedical subjects
A Burkhardt
Publications and source records attributed to A Burkhardt.
Oncologic applications for silicone gel sheets in soft-tissue contractures.
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[Oral manifestations in histiocytosis X. The clinical, radiological and therapeutic aspects].
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[Solitary plasmocytoma of the larynx].
Solitary plasmacytoma involving the larynx is very rare. To the best of our knowledge, there are only 73 cases reported in the world literature. The clinical picture was chronic cough, hoarseness and discrete dysphagia. Complete work-up to rule out systemic evidence of plasmacytoma is necessary. Microscopically, solitary plasmacytoma must also be distinguished from plasma cell granuloma.
[Pain and itching of the right breast following a fall on the right side of the thorax].
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Cellular events in alveolitis and the evolution of pulmonary fibrosis.
"Alveolitis", as opposed to "pneumonia" sensu strictiori, is a term used to denote diffuse inflammatory changes of the pulmonary parenchyma, excluding those that result from local bacterial, fungal or other extracellular microbial growth. The various types of alveolitis are classified according to their histological characteristics and range from "luminal phagocytic" or "mural lymphoplasmacellular" and "exudative" to "fibrosing" alveolitis. In this overview, various exogenous and endogenous causes of different types of alveolitis, and the cellular events in their pathogenesis are briefly discussed to illustrate the complex mechanisms involved. Particular emphasis is placed on the possible transition from diffuse exudative to fibrosing alveolitis. It appears that pulmonary fibrosis, which is usually patchy rather than truly diffuse, does not have a uniform pathogenesis. Besides the possibility of a certain degree of a diffuse fibrosis three major pathways are evident: (1) granulation tissue budding into alveolar lumina (luminal fibrosis) (2) exudate incorporation into alveolar walls (mural fibrosis) and--at least equally important--(3) so-called collapse (atelectatic) induration (obliterative-interseptal fibrosis), a process that has largely been neglected so far.
Dentin formation in so-called "fibro-osteo-cemental" lesions of the jaw: histologic, electron microscopic, and immunohistochemical investigations.
Two cases of the so-called fibro-osteo-cemental lesions of the jaws, containing unusual deposits of hard tissue, are described. There were peculiar spheroid calcifications or larger masses forming small cavities with a radial arrangement and discontinuous blasts extending with axonlike cell processes toward an acellular core. For further definition, electron microscopic and immunohistologic studies were done. The most conspicuous features were abundant intracytoplasmic vimentin filaments in the blasts, tight junctions, matrix vesicle formation, a globular accretion pattern, and so-called matrix maturation. These findings militate against an osseous or cementous nature of this hard tissue. Rather, both the light and electron microscopic findings are highly compatible with the assumption that the blasts are odontoblasts and that an immature type of dentin is formed. In addition to fibroblasts, osteoblasts, and cementoblasts, apparently also a further descendant of the ectomesenchyme--the odontoblasts with dentin formation--may participate in the so-called fibro-osteo-cemental lesions.
The E5 oncoprotein of bovine papillomavirus is oriented asymmetrically in Golgi and plasma membranes.
The E5 oncoprotein of BPV-1 is a 44 amino acid, hydrophobic polypeptide which is present in membrane fractions of transformed cell homogenates. To define the specific cellular membrane compartments with which E5 associates, immunofluorescence and immunoelectron microscopy were performed using an affinity-purified antibody specific for the E5 carboxyl-terminus. Two cell systems which overexpressed the E5 protein were analyzed: (1) Balb/c 3T3 mouse cells transformed by a BPV-1 cDNA expressing the E2-E5 ORFs, and (2) Sf9 insect cells infected with recombinant baculovirus expressing the E5 ORF. In both cell types, E5 protein was found in the membranes of the Golgi apparatus with its carboxyl-terminus oriented intraluminally. In the Sf9 cells, which synthesize much greater quantities of viral protein, E5 protein was observed additionally in plasma membranes with the carboxyl-terminus facing extracellularly. The concentration of E5 protein within the Golgi and plasma membranes suggests several potential mechanisms for inducing cellular transformation.
Alveolitis and collapse in the pathogenesis of pulmonary fibrosis.
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[Nonodontogenic mandibular cysts. Simple bone cysts in the maxillary area--pathogenetic and therapeutic aspects].
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[Involvement of the trachea and lungs in AIDS-associated Kaposi's sarcoma].
Kaposi's sarcoma is now the second most common AIDS-associated disease, Pneumocystis carinii pneumonia being the commonest. The clinical and radiological picture of bronchopulmonary Kaposi's sarcoma is often indistinguishable from that of nonspecific interstitial pneumonitis. Diagnosis of the sarcoma in the airways, and especially in the lung parenchyma, is difficult. The case of a patient with AIDS and bronchopulmonary Kaposi's sarcoma is presented and the diagnostic, therapeutic and prognostic problems are discussed.
Genetic and biochemical definition of the bovine papillomavirus E5 transforming protein.
Mutations surrounding the first methionine codon of the E5 transforming gene of bovine papillomavirus (type 1) were analyzed for their effect on cellular transformation and on the synthesis of the 7-kd E5 polypeptide. Frameshift mutations upstream of this methionine codon (bp 3879) affect neither transforming activity nor the ability to synthesize full-size E5 protein. In contrast, frameshift mutations distal to this position result in the inhibition of cell transformation and prevent synthesis or accumulation of E5 protein in cells containing the mutant viral genomes. Several in-frame mutations distal to the first methionine codon have a minimal effect on transforming activity but alter the electrophoretic mobility of the E5 protein in a manner consistent with the generated genetic alteration (deletion, insertion or substitution). In all cases where the protein is detected, it fractionates with cellular membranes and forms dimers. These studies indicate that (i) the methionine codon at bp 3879 serves as the initiation codon for the mature E5 protein, (ii) changing the charge of the E5 amino-terminus (from neutral to positive) does not prevent the association of this hydrophobic polypeptide with cellular membranes, and (iii) E5 amino-terminal mutations do not interfere with the ability of this polypeptide to form homodimers. We conclude that the major focus-inducing activity of the intact BPV genome is due to the function of the small polypeptide encoded in the 3' half of the E5 ORF.
Accumulation of anthracotic particles along lymphatics of the human lung: relevance to "hot spot" formation after inhalation of poorly soluble radionuclides.
Large lung sections of humans of advanced adult age revealed a markedly nonuniform retention pattern of dense anthracotic particle aggregates, with an impressive accumulation of this material along pulmonary lymphatics, i.e. the deep (peribronchial), septal (perivenous) and superficial (pleural) networks. Conversely, the alveolar parenchyme contained only occasional, small aggregates of macrophages heavily loaded with carbon, representing little more than 2% of this material in lung tissue. Although translocation kinetics of anthracotic particles cannot readily be compared to those of highly toxic alpha-emitting, poorly soluble radionuclides such as 239PuO2, lymphatic drainage of the latter over the years may also be expected to lead to a concentration of radioactive material along lymph vessels. Since human data on the effects of inhaled 239PuO2 are virtually lacking, the above distribution pattern is apt to help in identifying cells and other tissue components most heavily at risk. Findings are also relevant to the problem of "hot spot" formation in vivo and its possible sequelae. The latter are briefly discussed with regard to both stochastic and non-stochastic effects.
[Bone tumors of the jaw and face. Sources of error and problems in diagnosis and classification].
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Pathogenesis of pulmonary fibrosis.
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In vitro models for studying the molecular biology of carcinogenesis.
Although carcinogens cause various similar deleterious effects on rodent and human cells, only rodent cells can convert to malignancy in a quantitative, predictable fashion. Therefore, the control mechanisms involving indefinite proliferation and tumorigenicity are different. Human cell lines may exhibit normal or aneuploid chromosome constitutions with numerical or structural alterations frequently involving proto-oncogene loci, but fail to produce progressively growing tumors in nude mice. A new approach for obtaining human cells susceptible to malignant transformation by chemical or physical carcinogens is to use DNA from a cancer associated virus. Transfection of human papilloma virus (HPV) DNA associated with genital cancer can extend life-span of human cells; post-X-irradiated cells grow in agar suspension. Southern blot analysis of extracted DNA indicates that HPV sequences persist. Similar results are obtained with human fibroblast and epithelial cells.
[Odontogenic keratocyst--a retrospective study of its clinical picture, radiology, pathohistology and therapy].
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[Bone tumors in the area of the jaw--diagnostic problems in myxoid differentiation].
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