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Biomedical subjects

H David

Publications and source records attributed to H David.

At least 91 records · Page 5Linked to original sources
PubMed1987

Morphometrical findings from human and animal liver cells in physiological and pathological conditions.

An account is given in this paper of morphometric findings obtained from animal hepatocytes, following immersion and perfusion fixation, after enzyme induction, as well as during postnatal development and aging, together with findings recorded from human liver in preserved condition and after transplantation. The results are related to qualitative and functional changes. The following conclusions are drawn: Morphometric studies at cellular level and, in particular, studies into pathological changes for good success depend on the availability of control values which still have to be prepared primarily with regard to human liver. Given observance of optimum preparation conditions, the quantitative data obtainable from immersion fixation for all cell organelles are identical to those obtained from perfusion fixation. Generally, it is not sufficient to determine merely morphometrical data for individual cell organelles, since in many cases the pathological process does actually originate from displacement of relations among cell organelles. If misinterpretation is to be avoided, determination of quantitative data will not be sufficient for adequate assessment of functional or pathological changes, but additional qualitative description will be necessary of cell organelles and cellular correlations.

Aging↗
PubMed1987

Specificity of a Mycobacterium kansasii phenolic glycolipid (mycoside A) immunoserum.

The specificity of Mycobacterium kansasii anti-mycoside A antiserum prepared in rabbits injected with purified samples of the phenolic glycolipid was evaluated by an enzyme-linked immunosorbent assay. Chloroform-methanol extracts from representative strains of 23 mycobacterial species and 50 strains of M. kansasii showed that all strains of M. kansasii and the representative strain of M. gastri formed the antigen, whereas none of the remaining species (including M. leprae) formed it. Consequently, it was found that the antiserum was highly specific and useful for diagnostic purposes.

Animals↗
PubMed1987

[The significance of liver changes as the cause of death in kidney transplant patients (an analysis of 68 autopsy cases)].

An analysis of 68 autopsy cases from a total of 950 patients with renal transplantation in Berlin in 1970-1986 shows an average age at death of 39,6 years (15-56 years). The period between renal transplantation and death averaged 51,2 months (range: 1-912 months). Liver failure was the immediate cause of death in 30 cases. In 28 cases the liver disease was a secondary disease. The risk of dying from a liver disease rose with the interval between renal transplantation and death. 61-192 months after renal transplantation, liver disease was the cause of death in 70% of the deceased. Liver cirrhosis was observed in 24 patients (age 21-56 years) after a period from 24-192 months. In 1 case a liver carcinoma developed in a cirrhotic liver. 11 patients died in coma hepaticum, 29 patients had a chronic hepatitis. The findings are compared with clinical studies and individual autopsy reports and contrasted to causes of death in patients with chronic dialysis.

Adolescent↗
PubMed1987

[Allogeneic transplantation of the small intestine--animal experiments and a clinical retrospect].

Allogenic transplantation of small intestine has proved to be an alternative therapy for complex failure of intestinal functions. Attempts in that direction had been made over many years, but impressive were obtained only under conditions of modern immunosuppressive therapy. Hence, wider clinical application is imminent at an international scale. Reference is made in this paper to the authors' own experience obtained from mongrel dogs for an account of indications, surgical technique for collection of intestine and transplantation, perfusion and preservation of the donor organ as well as of various pathophysiological, functional, and immunological aspects. Results obtained at different centres are discussed, with reference being made to individual cases and clinical findings recorded from them. The survival rate of animals which have undergone transplantation of the small intestine provides evidence for the possibility of such organ transplantation and means a challenge to all involved in conventional intestinal surgery and modern medical transplantation.

Adult↗
PubMed1986

Uptake of 3H-dopamine in megakaryocytes and blood platelets measured by quantitative electron-microscope autoradiography.

We studied the uptake of dopamine by mature megakaryocytes and blood platelets in mouse spleen after a single intraperitoneal injection of 3H-dopamine. In order to compare the uptake of 3H-dopamine in mature megakaryocytes and blood platelets, we used quantitative autoradiography at the electron-microscope level. Dense accumulations of silver grains were observed on both mature megakaryocytes and blood platelets; all other tissue elements of the spleen exhibited considerably less dense labeling. No significant differences with regard to dopamine uptake were observed in megakaryocytes and blood platelets. This is in contrast to the previous finding of very different patterns of 3H-5-hydroxytryptamine labeling in mature megakaryocytes and blood platelets (Daimon and Uchida 1985). The results of the present study provide new evidence in favor of the hypothesis that the active uptake mechanism of dopamine through the plasma membrane is different from the uptake mechanism of 5-hydroxytryptamine.

Animals↗
PubMed1986

Postnatal development of hepatocytes following oxygen deficiency in utero.

Pregnant rats were exposed to altitude hypoxia (5,000 m = pO2 11.33 kPa) 8 h daily, from the 16th through 21st d of pregnancy. The livers of the newborn male rats were morphometrically examined by electron microscopy for both qualitative and quantitative parameters, on the 2nd, 5th, 11th and 22nd d of age and were compared with those of controls during the same periods of postnatal development. Substantive changes were exhibited by the mitochondria. Processes of autophagocytic decomposition were recorded (focal vacuolisation, formation of myelin structures). Volume densities on the 2nd (0.2041), 11th (0.2048), and 22nd (0.2495) d of age were clearly higher than in control animals and were all on a rising trend. Numerical density, on the other hand, trebled in the controls (0.0738 on the 2nd d and 0.2261 on the 22nd) and almost doubled in the hypoxia animals (0.0849 on the 2nd d and 0.1471 on the 22nd). In other words, the volume of the average mitochondrion was larger in hypoxia animals, whereas surface densities were lower. Hepatocytes differed from cardiomyocytes, in that increased autophagocytosis of mitochondria and glycogen was recordable from the former only on the 5th d. Glycogen levels of hepatocytes went up considerably, with the rise recorded from controls (0.0181 on the 2nd d and 0.1911 on the 22nd) being somewhat stronger than that observed from hypoxia animals (0.0276 on the 2nd d and 0.1742 on the 22nd). The changes postnatally recorded from liver cells in the wake of prenatal hypoxia are believed to be processes of adaptation which do not cause any irreversible damage.

Animals↗
PubMed1986

Sustained division of protoplast-derived cells from primary leaves of Pinus pinaster, factors affecting growth and change in nuclear DNA content.

Leaf protoplasts were isolated from apical and in vitro-induced axillary buds of Pinus pinaster Ait. seedlings. First divisions were seen after 8-10 days of culture in a 650 mOsm kg H(2)O(-1) medium in which glutamine was the sole nitrogen source. Colony formation was achieved in 6-7 weeks in a modified protoplast culture medium in which a reduction in the concentrations of both calcium and carbon was essential for sustained divisions. To maintain cell suspension growth, it was necessary to subculture every three weeks to a 170 mOsm kg H(2)O(-1) medium. Lowering the C/N ratio did not support better growth. Phenolic compounds were detected in stationary phase cultures. Analysis by HPLC indicated that the cinnamate pathway was involved in their synthesis. After 3 and 7 months of culture, 65 and 74%, respectively, of protoplast-derived cells had a nuclear DNA content comparable to that of leaf protoplasts.

Journal Article↗
PubMed1986

Symptoms, diagnosis and time in hospital. A polydiagnostic study of schizophrenia.

The relationship between diagnostic assignment and specific symptomatology on admission and the duration of the first hospital stay was investigated in 200 patients with a functional psychosis. There were considerable differences in the mean duration of stay in hospital for patients fulfilling different diagnostic criteria for schizophrenia: the broader the concept of schizophrenia, the shorter the duration of stay. In looking at symptomatology, it could be demonstrated that patients with formal thought disorder had the highest mean duration of first inpatient episode.

Diagnosis, Differential↗
PubMed1986

[The sinusoid wall of the liver in viral infections].

The elements of the "peri-sinusoidal functional complex" (i.e. non-hepatocytes, space of Disse, vascular pole of hepatocytes) can react to the presence of virus in the sinusoidal blood stream by retaining viruses, sometimes followed by viral proliferation, by reactive proliferation, or by degenerative changes in the cells which may culminate in cell death. Immune processes may be also activated or alternatively, there may be no response whatever to the viremia. In hepatitis B infection the principal changes are in the Kupffer cells and in the vascular pole of the hepatocytes. Along with immunologic responses there are proliferative and degenerative events in the Kupffer cells, which may deleteriously affect the sinusoidal cell membrane of the hepatocytes. These factors, as well as the receptor structure of these cell membranes, are regarded as responsible for the uptake of virus in the hepatocyte. Cytotoxic T-cells which have migrated to the region also play a role in the overall process. The point should be made, however, that these concepts are largely hypothetical and that hepatitis B virus particles have yet to be demonstrated in the peri-sinusoidal complex.

Animals↗
PubMed1986

[The vascular pole of hepatocytes: structure, function and pathology].

Structural and functional subdivision of the hepatocyte into a sinusoidal (vascular) zone, a lateral zone and a peri-canicular zone (adjacent to the bile canaliculi) highlights certain peculiarities of the vascular hepatocyte pole. In contrast to the total cytoplasm, this area is characterized by a high volume of mitochondria, altered peroxisome content, a high concentration of lipids and the absence of Golgi-apparatus. Of critical importance is the sinusoidal cell membrane: at birth, the hepatocyte of the rat bears some 1,000 microvilli, rising to 4,600 in the mature animal. The surface to volume ratio of this part of the cell is more than 250% of the overall cell ratio. The ectoplasmic area beneath it is of importance to the structural integrity and function of the cell membrane itself. Pathological changes such as formation of blebs, shedding of cytoplasm, detachment of portions of the vascular pole, emergence of phagocytic processes, production of atypical substances (i.e. amyloid precursors), are closely and interactively related to pathologic processes of other elements of this region (non-hepatocyte, space of Disse). The peri-sinusoidal functional complex, may have an importance for the pathology of the liver which has not been fully appreciated to date.

Aging↗
PubMed1985

Alteration of the ultrastructure of the pig liver after a continuous perfusion of six hours in vitro.

Livers of mini LEWE pigs were perfused continuously for 6 h on a novel perfusion system through the portal vein (laminar flow from 200 to 300 ml/min, pressure 270 Pa) and through the A. hepatica (pulsating flow from 100 to 200 ml/min, pressure: 10.6/5.5 kPa). The following perfusion media were used for determining the best conservation conditions at 10 to 12 degrees C: Pig blood/Krebs-Henseleit bicarbonate buffer 1:1; Pig blood/Ringer lactate solution 1:1; Pig plasma; Collins C 2 perfusion solution. After perfusion with Collins C 2 solution the hepatocytes show swelling and dilation of the granular endoplasmic reticulum; after perfusion with the other solutions the changes of the hepatocytes are negligible. The alterations of the sinusoidal wall cells depend on the perfusion pressure and flow and the composition of the solution. After continuous perfusion the sinusoidal walls are characterized by vesicles of endothelial cells, dilatation of the Disse space and fragmentation of hepatic microvilli.

Animals↗
PubMed1985

Effects of chloroquine on hepatocytic organelles in rat.

The administration of chloroquine (Resochin) in rats produces significant changes in the hepatocytic organelles, which are described by morphometric and biochemical methods. There is an increase in oxygen uptake by the isolated mitochondria together with an increase in the specific surface of cristae. Volume densities of mitochondria, lysosomes, rough and smooth endoplasmic reticulum and Golgi apparatus increase, while that of glycogen decreases. The affecting mechanisms are discussed.

Animals↗
PubMed1985

Ultrastructural morphometric examinations on the protection provided by prostacyclin against myocardial ischaemia.

Myocardial ischaemia in the dog lasting for three hours is followed by swellings of the mitochondria and dilatation of the sarcoplasmic reticulum. The volume density (Vv) of mitochondria in the peripheral ischaemia zone is 0.2890, that of sarcoplasmic reticulum is 0.0101. Prostacyclin was administered either i.v. or by triggering in conjunction with an intra-aortic balloon pump which led to an increase in the volume density of the mitochondria, mainly as a result of an increase in the volume of average mitochondria. The dilatation of the sarcoplasmic reticulum is reversed. It was not possible to prove in our investigations that prostacyclin provides protection against myocardial ischaemia.

Animals↗
PubMed1985

Association between mitochondria and rough endoplasmic reticulum (rer) in rat hepatocytes.

The relative contact area between rough endoplasmic reticulum and mitochondria of hepatocytes in newborn to 27 months old rats is described by morphometric methods. The contact area decreases from 52.62% to 27.46% of the mitochondrial surface between newborn and rats being 27 months old. However, there is an increase in the contact area per hepatocytic cytoplasm and in the fraction of rer in contact with mitochondria during the first days post partum.

Aging↗
PubMed1985

Postnatal development of myocardial cells after oxygen deficiency in utero.

Pregnant rats were kept at a simulated altitude hypoxia (5000 m = pO2 11.38 kPa) for eight hours every day from the 16th to 21st day of pregnancy. The heart musculature of the left ventricle of newborn male rats underwent electron microscopic qualitative and morphometric quantitative examinations on the 2nd, 5th, 11th and 22nd day. Prenatal hypoxia leads to delayed development of the heart. The reduced weight on the 2nd day compared with that of control animals is compensated on the 22nd day. Prenatal hypoxia causes matrix disintegration and cristolysis of the mitochondria. Volume density, which is lower on the 2nd day (0.24: 0.29 (control animals], reaches that of the controls by the 22nd day. But the specific surface density of the cristae mitochondriales is markedly higher in the animals subjected to hypoxia (2nd day 31.0: 20.6; 22nd day 44.0: 38.1). Prenatal hypoxia causes an increase, in the postnatal period, in the autophagocytosis processes, which normally already exist in the heart musculature; this is recognizable by an increase in the volume density of the autophagic vacuoles (2nd day 0.0049: 0.0034; 22nd day 0.0098: 0.0045). The changes observed are regarded as reversible, i.e. as adaptive processes.

Animals↗
PubMed1985

The hepatocyte. Development, differentiation, and ageing.

1. Being the main organ of the metabolic system, the liver, whose function undergoes numerous changes in the course of life, is an important object of investigation. For this reason research into the structure and the associated functions of the hepatocyte, which plays a central role in the liver, is of special significance. 2. The study was carried out on male rats from birth up to the 27th month of life. Data obtained through similar experiments on female rats are available. The weight of the liver increases from 0.274 g at birth to 23.2 g at the end of the 27th month of life. The relative liver weight in relation to 100 g body weight diminishes from 7.7-5.3% in the prenatal phase to 4.5-2.6% in the first days of life, and increases again to 5.5% in the 1st and 2nd months of life. This is followed by a repeated drop in the relative liver weight to as low as 3.2 per cent. 3. The volume of the extrahepatocellular space diminishes during foetal development. Haematopoietic cells decrease from 63% of the liver volume on the 15th day to 37% on the 18th day of gestation. Kupffer cells account for less than 3% of the total liver volume in foetal and adult rats. Their number in foetal livers accounts for 4% of the total number of cells and in adult livers for 37%. The relative increase by a factor of about 10 is accompanied by an increase in the total volume by 130 per cent. 4. The volume density of the extrahepatocellular space diminishes from 0.403 at birth to 0.134 after 6 months. Generally, the extrahepatocytic space remains unchanged from the 1st month onwards, accounting for 10-15% of the total volume. 5. The volume density of hepatocytes is 0.60 on the 15th foetal day, increasing to 0.85 till the 21st foetal day. After birth till the end of the period of investigation the volume density varies between 0.78 and 0.94. At birth the volume of hepatocytes is 5775.9 microns 3. It increases to 10,000 microns 3 up to the 2nd month. It diminishes again to 7388.8 microns 3 till the 24th and 27th months. 6. Initially, the volume of hepatocytes drops to below the volume at birth, followed by an increase of 99% compared with the value at birth till the 6th month. After that the volume diminishes again to 127.9% of the volume at birth.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗