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Biomedical subjects

A Hecht

Publications and source records attributed to A Hecht.

At least 55 records · Page 3Linked to original sources
PubMed1992

[Classification of causes of death in humans].

The cause of death of 2631 deceased persons (2418 adults, 213 children) was determined. Classification is proposed by monocausative, relatively monocausative, competitive and complex causes of death. This classification would be in accordance with types of dying, as suggested by Thieke and Nizze [17]. A comparison of results has revealed far-reaching agreement between the two principles of classification with regard to frequency distribution of causes, except for the category of complex causes which, however, was of minor importance in our investigations. This was attributed to the fact that classification was facilitated by consideration of epistemological approaches. Differences among categories of causes were attributable also to age and sex of the cases studied, both adults and children.

Adolescent↗
PubMed1991

Dynamic chromatin: the regulatory domain organization of eukaryotic gene loci.

It is hypothesized that nuclear DNA is organized in topologically constrained loop domains defining basic units of higher order chromatin structure. Our studies are performed in order to investigate the functional relevance of this structural subdivision of eukaryotic chromatin for the control of gene expression. We used the chicken lysozyme gene locus as a model to examine the relation between chromatin structure and gene function. Several structural features of the lysozyme locus are known: the extension of the region of general DNAasel sensitivity of the active gene, the location of DNA-sequences with high affinity for the nuclear matrix in vitro, and the position of DNAasel hypersensitive chromatin sites (DHSs). The pattern of DHSs changes depending on the transcriptional status of the gene. Functional studies demonstrated that DHSs mark the position of cis-acting regulatory elements. Additionally, we discovered a novel cis-activity of the border regions of the DNAasel sensitive domain (A-elements). By eliminating the position effect on gene expression usually observed when genes are randomly integrated into the genome after transfection, A-elements possibly serve as punctuation marks for a regulatory chromatin domain. Experiments using transgenic mice confirmed that the complete structurally defined lysozyme gene domain behaves as an independent regulatory unit, expressing the gene in a tissue specific and position independent manner. These expression features were lost in transgenic mice carrying a construct, in which the A-elements as well as an upstream enhancer region were deleted, indicating the lack of a locus activation function on this construct. Experiments are designed in order to uncover possible hierarchical relationships between the different cis-acting regulatory elements for stepwise gene activation during cell differentiation. We are aiming at the definition of the basic structural and functional requirements for position independent and high level gene expression. The result of these experiments will have important consequences for random gene transfer with predictable and reproducible expression of transgenes.

Animals↗
PubMed1991

Unusual volar dislocation of the lunate into the distal forearm: case report.

A case of a severe wrist injury (fractures of the scaphoid, capitate, hamate, and ulnar styloid process) with volar dislocation of the lunate into the soft tissues of the forearm is presented. This degree of displacement of the lunate is exceedingly rare, and we believe has not been previously reported. Possible mechanisms, hyperextension injury forcing the lunate forward out of the carpus, or contact between the volar wrist skin surface and another object or surface propelling the dislocated lunate into the forearm, are discussed.

Adult↗
PubMed1991

[Synergetics--a possible hypothetical approach to better understanding of pathologic processes].

Modern understanding of the human disease cannot be reduced only on the disturbed biological processes of the living organism. Disease as the consequence of the disorders of a complex system needs in the same sense a complex view. It is necessary to take in consideration the theory of systems, the concept of layers and the idea of the deterministic chaos. A helpful clamp to coordinate these different views seems to be the synergetics, the teaching of the cooperation in complex systems. Synergetics investigate the mechanisms of the self-organization, too. The self-organization is of great significance in the phylogenetic and ontogenetic morphogenesis. Especially all diseases which are characterized by the disorders in the differentiation the processes forming "Gestalten" are to understand as processes of the disturbed self-organization. These refers the malformations, the malignant tumours and the chronic diseases. Self-organization being a system-internal mechanism is to understand as a process which determines the behaviour of complex organized living systems in confrontation with their environment.

Biological Evolution↗
PubMed1991

[The contribution of modern biology to a better understanding of disease].

The human disease in its biological foundation must be congruent with the normal processes of the life and explicable by these. The simplified view on disease in the past with the reduction on its biological and physico-chemical course seems to become more and more insufficient and limiting to a comprehensive understanding. The discussion of the concept of disease from the standpoint of the epistomology needs in consequence of the so called new thinking the integrated inclusion of the systems theory, the theory of chaos and the concept of layers by Riedl. Taking this in the consideration a comprehensive understanding of disease is given. This allows to take into account as well its evolutionary conditionality, its human being as its individual, group, population and species specific characteristics. This kind of view emphasizes the necessity to complete the pragmatic reductionism by a comprehensive sight. In the consequence of such a thinking it seems easier to recognize the with the increasing complexity of the living beings emergent laws.

Adaptation, Physiological↗
PubMed1989

[Modern theoretico-cognitive problems of medical science].

The paper presents the opinion that the medical science supported by theoretical generalizations is directed to mastering its scientific cognition, which will enable medicine to reach theoretical levels. In theoretical pathology, it is essential, as the first step, to define the concept of a disease in terms of dialectical materialism, to develop the concept of human disease, to apply the principles of dialectical determinism in a step-by-step fashion, to be critical in using reductionism and related scientific substantiation of strategies to solve health problems.

Humans↗
PubMed1989

[Arteriosclerosis over time].

Arteriosclerosis is a process over time. It is described with reference to its historical dimension, evolution, aspect of comparative anatomy, and autonomy. The need is emphasized for examining this process in its discontinuity, with a view to realizing the variable nature of causative relationships at different stages of the disease. It is of particular interest to clear up the factors responsible for progression of the arteriosclerotic process. In this context, attention should be focussed at the process of aging and its importance to arteriosclerosis in interaction with exogenous noxae.

Aging↗
PubMed1989

[Arteriosclerosis as the reflected image of current problems of medical science].

Predominance of analysis over synthesis, lack of integrative perception and inadequate consideration of regulatory mechanisms, insufficient understanding of the dialectical relationship between animal and man as well as of human individuality, these are considered to be the most severe limitations on scientific cognition today. This appraisal fully applies to arteriosclerosis, as well. More attention ought to be given to its peculiarities as a chronic disease, to the role played by so-called risk factors and their causative implications as well as to the impact of senescence on chronic pathological alterations. Our present knowledge on the causative correlations implied is not sufficient for adequate prevention of the arteriosclerotic vascular disease. Nevertheless, it would make sense to reduce those factors which have been identified as risk-boosting, although only limited consequences can be expected from such an approach.

Animals↗
PubMed1988

Rat antibodies as probes for the characterization of progesterone receptor A and B proteins from laying hen oviduct cytosol.

The chicken oviduct contains two different hormone binding forms of the progesterone receptor, A and B. We have prepared rat antisera against both forms of the receptor partially purified from laying hen oviduct. The anti-progesterone receptor A antiserum reacts with both receptor forms on Western blots, while the anti-progesterone receptor B antiserum reacts mainly with the B form. Both antisera also react with the native progesterone receptor proteins as shown by sedimentation analysis of the antibody-receptor complexes. Receptors A and B are recognized on Western blots of total protein from dissolved tissue, indicating that both forms are likely to be physiological components. Epitope mapping experiments show that immunogenicity of both receptor molecules is restricted to structurally related protein domains of 28 kDa in receptor A and of 52 kDa in receptor B.

Animals↗
PubMed1988

A progesterone responsive element maps to the far upstream steroid dependent DNase hypersensitive site of chicken lysozyme chromatin.

We have investigated the influence of the 5'-flanking region of the chicken lysozyme gene on steroid dependent gene expression. By transient transfection of lysozyme-CAT fusion genes into the human breast cancer cell line T-47D, a DNA element was identified which stimulates CAT expression when transfected cells are treated with progesterone. This element is distinct from a second hormone responsive element (HRE) located in the lysozyme promoter region; it activates the lysozyme and the TK promoter, irrespective of orientation and distance, and is therefore referred to as hormone responsive element on its own. The location of this newly discovered HRE between -2250 and -1815 relative to the transcriptional start site, corresponds to the position of a steroid inducible DNase I-hypersensitive site in chromatin of oviduct cells. This observation suggests a physiological role for the upstream element. In vitro DNase I protection experiments revealed six binding sites for both progesterone and glucocorticoid receptors within the sequences of the upstream HRE. The three distal binding sites are not required for hormonal stimulation of the TK promoter, while the three proximal binding sites, which are contiguously arranged, work in a cooperative manner.

Animals↗
PubMed1988

Histoautoradiographic detection of 3H-thymidine and 3H-proline in the vascular wall of domestic swine in experimental atherosclerosis. Is there an effect of saturated/unsaturated fatty acids in high cholesterol diet?

In vitro labeling of arterial wall samples from domestic swine with tritiated thymidine or proline was used to establish the effect of unsaturated (sunflower oil) or saturated (beef tallow) fatty acids in the presence of enteral cholesterol on DNA and collagen synthesis. Histoautoradiography of samples incubated in vitro gives labeling patterns and indices comparable to in vivo labeling. Preliminary results show that these nutrient fats do not differ in their effect on the DNA and collagen synthesis of vascular wall cells both in the presence and absence of intimal changes.

Animals↗
PubMed1988

[The future of pathological anatomy and the paradigms in science].

The view is taken that the future of pathology can be perceived only in relation to the development of science in general and medical science in particular. Development of science should be seen in the dialectics of continuity and discontinuity. The power of this process depends on dialectic antagonisms, such as those between being and appearance, development of medical science and even more of biological science, and techno-scientific progress. Taking this in consideration, no principal change of trend in issues and methodology may be expected in pathological anatomy. However, differences will grow between the theoretico-experimental and clinical aspects of pathological anatomy.

Humans↗