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H David

Publications and source records attributed to H David.

At least 73 records · Page 4Linked to original sources
PubMed1990

Morphometrical characterization of isolated rat hepatocytes.

Mononuclear hepatocytes account for 81% of all isolated hepatocytes of adult rats and are 3800 +/- 209 microns3 in volume with a surface of 1191 +/- 44 microns2, while the other 19% are binuclear cells, 4735 +/- 688 microns3 in volume and 1347 +/- 72 microns2 in surface. The plasma membrane contains few microvilli and different amounts of blebs. The organelle-free ectoplasmic zone beneath the plasma membrane is 1-6 microns in width. The cell organelles are centralized around the cell nucleus. The mitochondrial volume density (Vv) is 0.402 +/- 0.028; this is twice as high as that of hepatocytes in situ of adult rats. This result together with an about 50% volume decrease of isolated versus hepatocytes in situ supports the interpretation that unstructured ground plasma in the form of cytopheres is emitted into the surrounding space, probably by shedding of cytoplasmic protrusions, leading to a rise in relative mitochondrial volume levels. To avoid misinterpretation of results obtained from studies directed onto the metabolism of isolated hepatocytes, due consideration should be given to these findings.

Animals↗
PubMed1990

Quantitative ultrastructure of isolated Kupffer cells of rat liver.

The average volume of isolated Kupffer cells of rat liver is 821 +/- 64 microns 3, the average surface being 423 +/- 24 microns 2 (599 microns 2, with cell processes included). The surface structure (pseudopodia, lamellipodia, filopodia, microvilli) of isolated cells is much less developed than that of Kupffer cells in situ. By morphometric characterization volume densities are 0.1264 +/- 0.0077 (SE) for mitochondria and 0.3591 +/- 0.0169 for lysosomal structures. The volume of mitochondria amount to 0.79 +/- 0.04 microns 3.

Animals↗
PubMed1990

[Depression and anxiety--a study for validating subtypes of depression].

Psychopathological analysis of the patterns of symptoms in 176 depressive in-patients disclosed in 73.3% of all patients the presence of anxiety symptoms: of these, 38.6% merely had diffuse anxiety, whereas 34.7% showed either additionally or alone specific anxiety symptoms such as phobias and panic attacks. Similar to the results obtained by dividing the patients into an "endogenous" and "neurotic" group, namely, that there was no difference between the subtypes in respect of triggering the depressive episodes by life events, or in respect of the suicide rate 30 months after discharge and in respect of a chronic course developing during the 2 years following the discharge, there was likewise no difference with regard to these criteria if the patients were subdivided into depressive patients without anxiety and those with anxiety symptoms. However, a subdivision of the depressive patients with anxiety symptoms into a group having only free-floating anxiety and a group with specific anxiety symptoms, resulted in a clear association with these criteria: If a phobia or panic attacks were present, triggering by life events was far more frequent than if there was only free-floating was more often chronic in the first group, but there was no difference in suicidality. The results indicate that it will be necessary to provide for a more differentiated classification of anxiety symptoms before deciding in clinical routine what steps to take wherever depression and anxiety symptoms are present side by side. The same applies to treatment studies.

Adjustment Disorders↗
PubMed1989

A psychosocial study of male prostitution.

A semistructured questionnaire was administered to 50 male prostitutes and 50 nonprostitutes matched on age, sex, and socioeconomic status. The questionnaire focused on areas pertaining to family, sexual and criminal history, current life situation, sexual practices with clients, substance abuse, etc. In addition, the Beck Depression Inventory and the Tennessee Self-Concept Scale were administered to 35 subjects from each group. Results indicated that there were differences between the groups but that these differences did not entirely support the demographic profile offered by previous researchers. Specifically, our findings suggest that factors related to family background may be less important as potential determinants for entry into prostitution than influences related to financial gain, sexual orientation (homosexuality), and early sexual experiences.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Trends and prospects of bio-medical electron microscopy.

Prognostic ideas of the development of the bio-medical electron microscopy in the forthcoming decades to the 21st century include following points: 1. Development and improvement of electron microscopes with which one and the same point of a tissue section can be analysed in a wide spectrum of magnifications ranging from optical light microscopic to molecular level. 2. Element analysis on a large scale and 3-dimensional analysis of a wide range of electron microscopes, including the 100 kV standard model, high-voltage electron microscopes as well as intermediary electron microscopes of 200 kV to 400 kV with complementary devices. 3. Expansion of procedures for computerised image analysis for representation, modelling, and stimulation of macromolecules and other particles. 4. Improvement of both the chemical and physical aspects of fixation and embedding methods (freezing procedures) for the purpose of getting closer to in situ conditions of cells and tissues. 5. Persistent enhancement of methods of immunocytochemistry and genetic engineering at supramolecular and molecular levels, including their combination with appropriate hardware configurations for analysis of normal and pathological life processes. 6. The electron microscope will continue to keep its established position in medical diagnosis as well as in the assessment of ultrastructural alterations in the course of diseases. This position will be strengthened and expanded, and the electron microscope will thus play a role in scientifically substantiated therapy.

Clinical Laboratory Techniques↗
PubMed1989

Growth and soluble proteins of cell cultures derived from explants and protoplasts of Pinus pinaster cotyledons.

Pinus pinaster Ait. cell suspension cultures were derived from chopped cotyledons and from cotyledon protoplasts. When transferred after 12 weeks in culture, growth of both cell types showed a lag of 5 days followed by an exponential phase of 14 days for the protoplast-derived cells and 23 days for the organ-derived cells. During the exponential growth phase, packed cell volume of protoplast-derived cultures increased 7-fold and that of organ-derived cultures 13-fold. During the stationary phase, the diameters of protoplast-derived cells averaged 80 microm and those of organ-derived cells 100 microm. After 30 days, the media containing protoplast-derived and organ-derived cells decreased in osmolarity by 50 and 120 mOs per kg water, respectively, and in pH by 1.4 and 2.0 units, respectively. Throughout the growth cycle, protein content per unit of packed cell volume was always at least 35% higher in the protoplast-derived cultures than in the organ-derived cultures. Two-dimensional electrophoretic separation of soluble proteins revealed three peptides present in protoplast-derived cells that were absent from organ-derived cells and two peptides present in organ-derived cells that were absent from protoplast-derived cells. Other peptides differed quantitatively between the cell types.

Journal Article↗
PubMed1989

[Ultrastructure of intralobular lymphocyte migration in the liver of hemodialysis patients].

Presence of predominantly small lymphocytes in sinusoids and their immigration into the Disse space as well as into intercellular spaces between hepatocytes were recorded by electron microscopy from liver biopsies of 11 in 18 haemodialysis patients. No degenerative alterations were recordable from adjacent hepatocytes. These findings were obtained from patients with acute hepatitis (one case), minimal or chronic persistent hepatitis (two cases), reactive hepatitis (three cases), lobular and portal hepatitis (one case) as well as from the cases of metabolic-toxic alterations and one case of chronic blood congestion. HBV antigens were serologically identified in six cases. A HBcAg-free HBsAg type was immunohistologically diagnosed in one case only. No correlation was found to exist between the morphological results, on the one hand, and cellular immune pattern in peripheral blood, on the other. The above findings differed from most investigations of hepatitis B cases, in that no evidence could be found to cytotoxic action of lymphocytes upon adjacent hepatocytes. More investigations will be required for interpretation of the above findings, primarily immuno-electron microscopic studies.

Cell Movement↗
PubMed1989

[The position of the liver in the pathogenesis of atherosclerosis].

The review deals with two complexes: 1. Role of hepatocytes in the origin and course of general atherosclerosis. 2. The "Perisinusoidal Functional Unit" as pathogenetic factor in atherosclerosis. The central place of hepatocytes in the metabolism of lipoproteins of both exogenous and endogenous origins points to the fact that hepatocytes have a key function in the pathogenesis of atherosclerosis. In order to play their role in the metabolism, lipoproteins have to be capable of reaching the hepatocytes and of getting back from them into the circulation. The requisite for that is the passage of lipoproteins through the sinusoidal wall, i.e. the endothelial sieve. Its structuring is thought to be the cause for both distinct manifestation of atherosclerosis in different species, especially due to exogenous supply of lipids, and increasing risk of atherosclerosis, e.g., by nicotine or certain drugs. The following question might be derived from latest international research: "Is atherosclerosis a liver disease with secondary consequences for the vascular system?"

Arteriosclerosis↗
PubMed1989

Changes in the nucleotide metabolism of Ehrlich ascites tumour cells during their growth in vivo.

During the transition of Ehrlich mouse ascites tumour cells from the proliferating into the resting phase of growth a tremendous loss of purine and pyrimidine compounds was quantitated by ion-pair reversed-phase high performance liquid chromatography. This change is accompanied by a distinct decline in the incorporation rates of adenine, hypoxanthine, and adenosine. Inorganic phosphate stimulates the low rate of hypoxanthine incorporation of cells in the plateau phase, but lacks any effect on the high rate during proliferation. The mitochondria suffer structural deteriorations and decrease in their cellular content in the course of the plateau phase; however, other changes were not seen by morphometric analysis. The interrelations between nucleotide metabolism, mitochondrial content and the rates of formation and consumption of ATP are discussed.

Adenine↗
PubMed1988

Pathology of hepatic peroxisomes in chronic hepatitis B and immunosuppression.

After kidney transplantation and immunosuppressive therapy patients with chronic hepatitis B show not only peroxisome proliferation in hepatocytes but also additional alterations of these organelles: lysis and occasional complete loss of peroxisomes in HBsAg areas as well as lysis and/or autophagocytic degradation of peroxisomes in hepatocytes which contained hepatitis-B virus particles. Two mechanisms are suggested as being significant for the numerical decrease of peroxisomes in HBsAg areas: Reduced neogenesis, but typical lytic degradation; Direct toxic action of immunosuppressive substances. For elucidation further studies have to be undertaken.

Autophagy↗
PubMed1988

Rudolf Virchow and modern aspects of tumor pathology.

Rudolf Virchow (1821-1902), the great German pathologist of the 19th century, founder of the "Zellularpathologie", also dealt with principal problems of tumor pathology. His theoretical concepts concern the definition and characterization of the tumor process, the dignity and diagnosis, published especially in his 3 monographs "Die Entwicklungsgeschichte des Krebses" (1847), "Handbuch der speciellen Pathologie und Therapie" (1854) and "Die krankhaften Geschwülste" (1863-65). The achievements of Rudolf Virchow are not related to the description and diagnosis of specific tumors together with their genesis and interpretation. There have been quite a few errors and false concepts which can longer be accepted today. The timeless modernity and topicality of Rudolf Virchow's postulations on tumor pathology is based on his general conclusions which as key propositions have retained general validity throughout more than a century. They have been confirmed and further interpreted by knowledge which has been accumulated largely over the past one or two decades in the fields of tumor research, electron microscopy, molecular biology, genetics, and immunology.

Germany↗
PubMed1988

Development of a direct assay for alpha-amylase.

We describe a direct colorimetric assay for alpha-amylase, with 2-chloro-4-nitrophenyl-alpha-maltotrioside as substrate. Both human pancreatic and salivary amylase split this substrate without the use of helper enzymes, yielding free 2-chloro-4-nitrophenol, which is monitored at 405 nm. The performance of this reagent compares well with that of Pantrak Amylase (Behring Diagnostics) for both serum and urine samples. The reagent is very stable in dry powder form and is stable for one month at 2 to 8 degrees C after reconstitution. Because of the rapid color development and linear kinetics (less than 30 s), the assay is easily automated. Results can be obtained in less than 5 min.

Chromatography, High Pressure Liquid↗
PubMed1988

[Autopsy analysis of the cause of death in patients with kidney transplants].

68 cases of autopsy of 950 patients who underwent a kidney transplantation in Berlin from 1970 to 1986 were analysed with regard to their main disease, the disease directly leading to death and secondary disease. The average age of the deceased was 39.6 years (15-56 years), the duration between kidney transplantation and death was 51.2 months (1-192 months). In the first place there are diseases of the liver (30 times primary disease, 28 times secondary disease), in which cases 24 times a liver cirrhosis was existing and in 11 cases a coma hepaticum caused death. Apart from this septic-septicopyaemic processes (23 times) were of great importance for the exitus, in which cases there were frequently close relations to liver diseases (10 times liver diseases primary disease, 12 times secondary disease). Furthermore are important for the occurrence of death the renal hypertension as well as hemorrhages particularly in the gastrointestinal tract. 15 times a diabetes mellitus was stated, in 13 cases severe changes of bones and joints were diagnosed. 4 times a neoplasia was present (3 times immunocytoma, once liver carcinoma). The diseases diagnosed are to be regarded as a sequela of the primary disease, above all, however, caused by the long-lasting immunosuppressive therapy and the influence on the endocrine system.

Adolescent↗
PubMed1987

The concept of the "perisinusoidal functional unit" of the liver--importance to pathological processes.

Non-hepatocytes account for 30 per cent of cells in the liver, with sinusoid-coating endothelial and Kupffer cells being the most common types. In addition, there are some scattered pit cells in the wall. Ito cells (perisinusoidal cells, lipocytes) are located in the Disse space. In this paper a review is given of structural and functional changes of cells in response to pathological conditions with reference to the importance of such changes due to diseases of the liver and the organism in large. Cooperation and interaction among non-hepatocytes, the vascular pole of hepatocytes, and Disse space as the site of reaction are summarised under the concept of the "Perisinusoidal Functional Unit", and the concept is explained in greater detail by examples (lipoprotein catabolism, processes of phagocytosis, vitamin A storage, virus infections, accumulation of pathological substances, fibrosis, and capillarization).

Alcoholic Intoxication↗
PubMed1987

The perisinusoidal functional unit in amyloidosis.

The close morphological and functional relations between the various components of the perisinusoidal functional unit may be demonstrated by combination of ultrastructural results with the latest findings in the context of intra-hepatic synthesis and transformation of amyloid. The precursors of amyloid, synthesised in hepatocytes in the region of the endoplasmic reticulum, lysosomes, and plasma membrane of the vascular pole, are moved into the vascular system together with high-density lipoproteins which are probably identical with lipoprotein vesicles close to plasma membranes and in Disse space, and in the vascular system they are transformed to Serum Amyloid A (SAA). A certain role is probably played by Kupffer cells in polymerisation of amyloid A to fibrils. Growing accumulation of fibrils causes ligature and melt-off of peripheral parts from the vascular pole of hepatocytes, with its volume being substantively reduced, so that the spacing between plasma membrane and nucleus may reduce from something between 10 and 12 micron to below 1 micron. There is neither any compression of cytoplasm nor translocation of organelles. Hence, the process can be interpreted as a specific form of atrophy.

Amyloid↗
PubMed1987

31P-NMR spectroscopy and ultrastructural studies on nephrotoxicity of cyclosporine A.

NMR-spectroscopy and electron microscopy were applied in order to find out whether nephrotoxic effects of cyclosporine A in combination with ischaemia on rat kidney are of significance for the energy metabolism of the organ. CSA was administered in daily doses of 15 mg/kg rat over 20 days. Use was made of the particular advantage of 31P-NMR-spectroscopy to follow up the dynamics of high-energy phosphate concentrations in the same tissue. Ultrastructural changes were observed in the region of the proximal tubule. Some mitochondria showed degenerative changes, others increased density of cristae. The total number of mitochondria was increased. This observation together with the coexistence of vacuolarly degenerated mitochondria and mitochondria with increased activity after CSA treatment is interpreted as expression of a compensatory mechanism that keeps constant the totality of high-energy phosphates despite damage to some mitochondria.

Adenine Nucleotides↗