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H David

Publications and source records attributed to H David.

At least 145 records · Page 8Linked to original sources
PubMed1980

[Methods for the determination of the surface density of myocardial cell membranes with special regard to the mitochondrial cristae].

The possibility of using modified formulas for determining the surface density of cellular membranes of the heart muscle cell was discussed, sarcoplasmic reticulum and particularly mitochondrial cristae being used as examples. By using modified formulas and different stages of magnification it could be possible to determine the surface density of critae also in such experimental conditions in which the mitochondrial cristae appear to be densely packed.

Animals↗
PubMed1980

[Structure and function of the myocardial cell in various forms of adaptation].

Comparative ultrastructural morphometric and physiological examinations of the rat's myocardium after swimming exercise, hypokinesia and hypobaric hypoxia show concurrence between morphometric and contractility parameters. Differences in the changes of cell organelles in general and of mitochondria and sarcoplasmic reticulum in particular observed in the experimental models of adaptation used provide a basis for making inferences as to different structural reaction patterns of the myocardial cell. Special importance is attached from the functional point of view to changes in the volume and membrane surface density of the longitudinal sarcoplasmic reticulum and in Golgi's apparatus. Different structural reaction patterns suggest different adaptation mechanisms of the myocardial cell.

Adaptation, Physiological↗
PubMed1979

Quantitative and qualitative changes in the mitochondria in hepatocytes during postnatal development of male rats.

The volume density of mitochondria increases during postnatal development of the hepatocytes of male rats (test ages: 0 [birth], 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 14th, 21st, 28th day and 2nd, 3rd, 4th, 5th and 6th month) from 0.165 at birth to 0.236 on the 14th day, after which it decreases to 0.139 until the 6th month. At the same time the absolute volume of the mitochondria of the hepatocytes increases from 728.8 micrometer 3 at birth to 1225.5 micrometer 3 on the 14th day and reaches a maximum of 2102.3 micrometer 3 at the end of the 2nd month. The number of mitochondria per hepatocyte is 204 at birth. It increases continuously and reaches 2199 at the end of the 6th month. The volume of the average mitochondrion on the other hand diminishes during postnatal development from 3.83 micrometer 3 at birth to 0.64 micrometer 3 towards the end of the 6th month. Transverse divisions of mitochondria, budding of parts of mitochondria, autophagocytotic processes and degenerative changes can be observed throughout this period.

Animals↗
PubMed1979

Some recent results of the quantitative characterization of heart muscle cells.

The present situation of the quantitative characterization of the heart muscle may be summarized as follows: 1. There exists a great collection of quantitative data of the heart at the macroscopical, microscopical, and ultrastructural levels. 2. These data allow for the explanation of several life processes and of the pathogenesis of various diseases. 3. Correlations between cellular structures and biochemical processes can be realized by quantitative data, especially volume, number, and surface. 4. At present it is necessary to standardize the methods in order to obtain a better comparability of the results. 5. Moreover, the three levels should be correlated because only then numerous results may interpreted correctly. 6. All existing quantitative results show significantly that the isolated recording of quantitative data is an insufficient as is the description of qualitative results. The combination of quantitative and qualitative findings leads, however, to completely new results of higher scientific value which form--in combination with biochemical findings--the basis of the knowledge of normal and disturbed life processes.

Aging↗
PubMed1979

[Alterations of the volume and surface of liver cells of male rats during postnatal development].

To characterize the postnatal development of hepatocytes of male rats quantitative, morphometrical investigations of male rat livers were carried out at the following times: day of birth, 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 14th, 21st, and 28th day as well as 2nd, 3rd, 4th, 5th, and 6th month. Several methods were used to determine the cell volumes and surfaces as a whole, the nucleus, and the sinusoidal (supranuclear), lateral, and bile cancliculi-near cellular zone, as well as the sinusoidal, lateral, and bile canaliculi-near plasma membrane. The cellular volume increases from the day of birth (5,775.9 +/- 545.5 micrometer 3) till the 6th month to 11,494.2 +/- 1,241.6 micrometer 3. At the same time, the liver cell surface increases from 1,900 micrometer 2 to 3,191.7 micrometer 2. The number of microvilli of the sinusoidal plasma membrane increases from 1,074.4 to 2,170.0, and of the plasma membrane limiting the bile canaliculi their number changes from 248.9 to 340.2. The values of the liver volumes and surfaces of adult animals differ from those in the literature, as they are based on mononuclear cells only (i.e., the about 30% binuclear cells are not taken into account) and a smooth surface without considering the existence of microvilli. The nuclear volumes increase from 412.7 +/- 28.2 micrometer 3 (birth) to 549.5 +/- 440 micrometer 3, whereas the relative percentage decreases from 7.14% to 4.78%, which corresponds with the findings of other authors. The proportion of the 3 zones of the cytoplasm changes in the following way : day 0 (birth) : sinusoidal zone: 2,224 micrometer 3 = 36.8%; lateral zone: 1,473 micrometer 3 = 25.9%; bile canaliculi-near zone: 1,017 micrometer 3 = 17.7%; end of 6th month : sinusoidal zone: 4,000 micrometer 3 = 34.8%; lateral zone: 4,724 micrometer 3 = 40.0%; bile cancliculi-near zone: 1,345 micrometer 3 = 12.1%. Taking into account other findings our investigations suggest that the postnatal development of the male rat liver can be definitely characterized by determining the parameters at the following dates: day of birth, 3rd, 4th, 5th, 7th, 14th, and 28th day, 3rd and 6th month.

Aging↗
PubMed1978

Quantitative ultrastructural characterisation of rabbit erythroblasts and of 3H uridine incorporation into their nuclear components.

Electron microscopic-autoradiographic and morphometric investigations were carried out in erythroblasts from rabbit bone marrow. 1. to obtain quantitative data for the erythroblast classes. 2. to determine quantitative-morphometrically the incorporation rate of 3H uridine into the cell components of the different erythroblast classes. 3. to evaluate the influence of UV irradiation on the incorporation of 3H uridine. According to ultrastructural criteria erythroblasts are divided into 3 classes: basophilic erythroblasts (BE), polychromatic erythroblasts (PE) and orthochromatic erythroblasts (OE). The areas of the 3 classes of erythroblasts are in a ratio of 1:0.5:0.43. In all classes the portion of the nucleus is between 56 and 58.8%. The portion of mitochondria decreases from 13.3% (BE) to 9.3% (PE), and to 6.3% (OE) respectively. Simultaneously the portion of heterochromatin in the nuclear area rises from 24.2% (BE) to 49.8% (PE), and to 63.2% (OE) whereas the percentage of euchromatin decreased correspondingly. Nucleoli were found only in 78% of the BE and in 3.4% of the PE. For the quantitative determination of the silver grains and silver filaments, respectively, the morphometric procedures have been adapted to the particular conditions. So it was necessary to estimate the areas covered by silver grains of filaments. The silver grains or filaments localised in the nuclear area are in the range from 84.6 to 93.4%. The percentage of silver grains of the total cellular area is 14.4% in BE, 6.8% in PE and 4% in OE. In a similar way the relative values of the nucleolus (total) and the euchromatin and heterochromatin are reduced. UV irradiation of bone marrow in vitro for 10 to 20 min does not cause any significant changes in the incorporation of 3H uridine. This result is in contrast to other published experiments on the influence of UV on the RNA synthesis. It is assumed that the irradiation dose was too low to induce a measurable effect on the RNA synthesis or the point of investigation was too early.

Animals↗
PubMed1978

[Electron microscopical findings of the myocardium in Fallot's disease and of the ventricular septal defects (author's transl)].

Ultrastructural quantitative and qualitative investigations of the myocardium of 7 children with Fallot's disease and 3 children with a ventricular septal defect (VSD) have shown bizarre nuclei and a slight increase in the myofibril share of the volume (Fallot's disease: 51.22%; VSD: 56.85%). This may be interpreted as a sign of a cellular hypertrophy. The mitochondria have a proportion of 35.07% and 33.75%, respectively. The glycogen content is relatively high. The lipofuscin bodies originate mainly from mitochondria having a percentage of 1.43 and 1.67, respectively. Particular signs of a lesion could not be observed. From the ultrastructural findings on the morphology of heart muscle cells it can be deduced that operations of vitia may be safely carried out.

Adolescent↗
PubMed1978

[Electronmicroscopic changes in the myocardium of children with cyanotic heart diseases].

In 7 children with Fallot's tetralogy ultrastructural quantitative and qualitative investigations on the heart muscle were carried out. Bizarre nuclei and slightly increased volume of mitochondrial part indicated hypertrophy. The amount of mitochondria was 35.07 per cent. The content of glycogen is relatively high. The lipofuscin bodies, mainly originating from mitochondria, amount to 1.43 per cent. No essential damage is observed. From the ultrastructural findings can be concluded that surgery may be done without suspicion as to cardiac cell morphology.

Cell Nucleus↗
PubMed1978

[Experimental studies on surgical therapy of acute infarct].

The authors examined the effects of reperfusion after temporary ischemia in 50 dogs. The morphologic alterations were documented by methods of electron microscopy, fluorescence microscopy, and histochemistry. Lactate and activity of glycogen phosphorylase were assessed. According to the results, the optimal ischemia interval is 30 to 60 minutes for rational application of reperfusion, while it is just possible after 120 minutes. After a 4-hours-period of ischemia reperfusion increase morphologic damage of myocardium and impairment of myocardial metabolism. Prolonged reperfusion of 7 days resulted in a reduced extent of infarction compared with controls. In non-ischemic myocardium the morphologic and metabolic alterations were less expressed. The effects of "no-reflow"-phenomenon and conclusions for clinical practice are discussed.

Animals↗
PubMed1978

[Reperfusion of the myocardium after acute ischemic lesion].

In a complex experimental study on 52 dogs the myocardium was examined after ischemia and reperfusion of various duration. Morphologic, metabolic, and functional findings proved that a short-term reperfusion after coronary occlusion for more than 2 hours has disadvantageous effects on the regression of ischemic lesions. During the early period (up to 3 days) this is caused by the "no-reflow" phenomenon. Combined qualitative and quantitative findings are required for correct appraisal of the ultrastructural alterations after reperfusion. In acute coronary occlusion, early revascularization after passing the crucial initial phase is advantageous, because the extent of myocardia necrosis is decreased by the prolonged reperfusion, thus leaving a larger myocardiac reserve in case of re-infarction. Clinical conclusions are drawn.

Animals↗
PubMed1978

[Ultrastructural and functional changes of rabbit myocardium after cholesterol feeding].

The myocardium was ultrastructurally investigated immediately after 12 weeks of feeding in one part of the animals and in the remaining animals 27--30 months after termination of the feeding period. At the same time, parameters of the myocardial contraction were measured immediately after the feeding at isolated trabeculae of the left ventricle and 27--30 months after the termination of the feeding at the left ventricle in situ. After the 12 weeks of feeding the morphometrically estimated intracellular lipid content rises from 0.23% (normal) to 5.26%. The mitochondria decline from 36.98% (normal) to 29.08%. The sarcoplasmic reticulum (SR) changes in a vesicular or vacuolar manner respectively. The contractility index Vmax of isolated trabeculae decreases insignificantly. The resting potentiation and the diastolic stiffness are increased. 27--30 months after termination of feeding the lipid content and the mitochondria are normal in comparison to controls of the same age. The vacuolar changes of SR and its cellular portion are increased. The contractility index of the heart in situ max (dp/dt)/P is decreased insignificantly. The velocity of relaxation is enhanced in comparison with controls. By comparing ultrastructural and functional findings it can be seen that variations in the contraction performance are accompanied by stronger changes of the cellular structure immediately after the feeding than 27--30 months after the termination of the feeding. At this time continuing small alterations in the contraction performance of the heart in situ are observed in addition to the reversibility of various characteristics of damage together with an increase in the Ca++-transporting SR and its alterations.

Animals↗
PubMed1978

[Comparative study on the dependence of quantitative results in the electron microscopic autoradiography on the type of developer (Microdol X, Phenidon) (author's transl)].

It was the aim of the investigation to compare quantitative results of electron microscopic autoradiographs after the use of different developers (Microdol X, Phenidon) adapting morphometrical methods. Erythroblasts of rabbit were tested after incorporation of 3H-uridine in vitro. Both developers showed the same tendency at higher rates of incorporation (basophilic erythroblasts and polychromatic erythroblasts). Using Phenidon, however, we could obtain only half the values for the individual cell components. At high rates of incorporation Microdol X results in an overlapping of the silver filaments. Thus, more distinct grains can be reached by Phenidon. At smaller rates of incorporation (orthochromatic erythroblasts) after using Phenidon a quantitative evaluation is however influenced by too many factors of uncertainty so that according to our investigations Microdol X is better suited for a quantitative evaluation of electron microscopic autoradiographs.

Autoradiography↗