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H David

Publications and source records attributed to H David.

At least 163 records · Page 9Linked to original sources
PubMed1977

[Position and problems is morphological characterizing of aged cells and organs (author's transl)].

Cellular changes in the process of aging are non-specific. A combination of nuclear inclusions, invaginations of the nuclear membrane, a reduction of the number of mitochondria with a simultaneous increase in size to the point of development of megamitochondria, a disorganization of the endoplasmic reticulum and a decrease of its surface density, an increase of the lysosomal volume share and a lipofucin accumulation indicates the existance of an aged cell. On the macroscopical and microscopical levels a diagnosis on the age of an organ is impossible.

Adult↗
PubMed1977

[Quantitative and qualitative changes in the heart muscle of the left ventricle in male rats during development and maturation in the first 6 months of life].

In order to characterise the postnatal development and maturation of heart muscle cells the musculature of the left ventricle of male rats has been investigated electronmicroscopically at birth, at the 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 14th, and 21st day of life, as well as after the 1st, 2nd, 3rd, 4th, 5th, 6th month. On the basis of these investigations quantitative and qualitative data have been obtained. The development of the heart muscle cells is characterised by 2 processes. 1. Processes of synthesis and development - The ribosomes/polysomes which are to be found in great numbers are a characteristic of the synthesis of the myofilaments which plays an important role in the 1st phase of postnatal development. This synthesis of myofilaments takes place in the sarcoplasm by the formation of new individual myofilaments, in the interior and at the border of existing myofibrils, and at the level of the Z-lines. Mitochondria are developed in particular by the germination of small mitochondria the percentage of which amounts to about 16% at birth. The sarcoplasmic reticulum is developing in its longitudinal as well as transversal forms only during the 1st month. The disci intercalares, however, have been formed in the main already at birth. Cells are furthermore developing by mitotic processes during the first days. 2. Degradation processes - 2.1. The degradation is characterised by focal autophagocytotic processes in mitochondria concerning the cristae as well as the matrix and the outer membrane. During these processes autophagocytotic vacuoles are developing partly with myelin membranes. In addition, whole mitochondria are transformed into autophagocytotic vacuoles. Later on, mitochondria are also condensed and transformed into mitochondrial lipofuscin. 2.2. The autophagocytotic degradation of glycogen together with the sequestration and formation of vacuoles and myelin membranes are particularly striking. Lipofuscin, however, is to be observed in larger quantities only from the 4th month onwards. The investigations have shown that decisive phases of development can be determined: the day of birth, the 3rd, 4th, 5th, and 7th, and 14th day, as well as after the 1st, 3rd, and 6th month. This determination of the specific developmental phases of the heart muscle makes it possible to carry out investigations in a more economical and purposeful way.

Animals↗
PubMed1976

Perinatal mortality after epidural analgesia.

A retrospective survey has been carried out of 6442 births during 1973-1974 in Cardiff. Lumbar epidural block had been administered to the mothers of 13-7% (885) of the births, the principle indication being relief of pain. In the management of the mother special emphasis was laid upon avoiding aorto-caval compression. The perinatal mortality associated with epidural block (14-8 per 1000) was not significantly different from that after other forms of analgesia (19-2 per 1000). There were less first week deaths in babies weighing less than 2-5 kg after epidural block (0 of 45) than in those who had other methods of pain relief (41 of 414) (P = 0-023). The choice of maternal medication did not influence the perinatal mortality rate of the immature baby, but there is a positive but non-significant, trend in favour of epidural block in the premature baby. This improvement in mortality could simply be related to the increased use of forceps delivery associated with epidural block. A controlled trial of epidural block is therefore indicated in the management of the premature fetus. In babies over 2-5 kg, or, those who were immature, epidural block was not associated with a reduction or increase in perinatal mortality.

Adult↗
PubMed1976

[Electron microscopic and light microscopic studies of optical and cortical afferents in the lateral geniculate body, pars dorsalis, of albino rats with special attention to synaptic organization].

1. In the CGLd of the albino rat there are to be found two forms of retinal terminals in electronmicroscopic investigations, they are identical with 2a and 2b terminals described formerly in Golgi-preparations. 2. The small 2b terminals are situated previously in the extraglomerular neuropil, which is identical with the terminal part of P-neuron dendrites. They establish asymmetric GRAYtype I contacts with dendrites and spines of the relay-cell-dendrites. 3. The large 2a terminals form filamentous contacts with the smooth surfaces of the dendrites of the stem-and branching-zones. Synaptic contacts (GRAY I) are established with the grape-like appendages in the branching zone of P-neuron dendrites. 4. In the glomeruli of the CGLd there are three main components, which are the nerve endings of large optic axons, the interneuron dendritic terminals and the relay-cell-dendrites. They are surrounded by astrocytic processes. 5. In the extra-glomerular neuropil there are numerous small nerve endings, they form GRAY type I contacts with relay-cell-dendrites and their spines. They are partly identical with the type I endings in Golgi-preparations (cortical terminals). 6. After the eye enucleation and ablation of the visual cortex the type 2a and 2b and type 1 terminals degenerate. There are two forms of degeneration, the light and the dark one. 7. After eye enucleation two forms of degenerations in the degenerating retinal axons occur, which are the "watery" and the "dense" form. Besides the astrocytes the oligodendrocytes remove the destroyed particles. 8. The ultrastructural characteristics of the interneuronal dendritic terminals and their possible funktion are discussed. 9. There is added a table of the synonyma of CGLd structures.

Animals↗
PubMed1976

[Reaction of the rabbit brain to locally applied deep temperature (light- and electronmicroscopy findings)].

Investigations by light and electron microscopy showed more details of potential patterns of injuring after application of low temperatures to rabbit brain. The authors were actually concerned to transforming the intensity of cooling into exact and reproducible degrees of necrosis. According to these experimental results, the application of cryotechnique to human central nervous tissue is just permitted on special premises (size of probe, low-level of temperature, and period of application).

Animals↗
PubMed1975

Doppler ultrasound and fetal activity.

The possibility that Doppler ultrasound, as used in routine fetal monitoring by external cardiotocography, might stimulate fetal activity was investigated. A mean increase in fetal activity of over 90% was found, as judged by the fetal movement count.

Female↗
PubMed1975

Free and membrane-bound ribosomes and polysomes in hippocampal neurons during a learning experiment.

The ribosomes of the CA1 and CA3 pyramidal cells of hipocampus were investigated by morphometric methods after the acquisition of a shock-motivated brightness discrimination in rats. A significant increase in the total number of ribosomes was observed in CA1 cells of trained animals and in CA3 cells of both active controls and trained rats. A significant increase in membrane-bound ribosomes was obtained in CA1 and CA3 cells after training only. The results confirm the suggestion of an increased protein synthesis in hippocampal neurons during and after the acquisition of a brightness discrimination, as we have concluded from out previous investigations on the incorporation of labeled amino acids under identical experimental conditions. The results lead to the assumption that the protein synthesis in some neuronal cells may probably differ not only quantitatively, but also qualitatively in trained and untrained animals.

Animals↗
PubMed1975

Quantitative changes of canine diaphragm muscle cells following electrostimulation.

1. In 12 dogs the right part of the diaphragm was stimulated 4, 5, 8, 11, and 14 weeks by means of a pacemaker. 2. Essential findings have been the increase of the amount of glycogen after 5 weeks, the increase of myofilaments per myofibril after 8 weeks, and the increase in the share of mitochondria in the 11th week. After 14 weeks all values have reached again their initial level as the result of an adaptation. 3. From the quantitative structural findings it can be taken that the diaphragm musculature is not changed by the electrostimulation in such a way that the functional preconditions for covering heart muscle deficiencies by diaphragm flaps are given.

Animals↗
PubMed1975

[Light and electron microscopic studies of slowly adapting abdominal stretch receptors of the American river crayfish Orconectes limosus (RAF)].

The slowly adapting abdominal stretch receptors of Orconectes limosus (RAF) have been investigated morphologically; 1. Despite their variety of size and shape all slowly adapting receptor neurons show common characteristic features which in addition distinguish them clearly from the fast adapting receptor neuron type SN2. The slightly globular cells have always several dendrites (often 4-6). They originate apical or lateral to the neuron, are oriented mainly longitudinal to the muscle fibres and are brodly ramified. The fine dendrites form a 3-dimensional fibrilar network. 2. The structure and distribution of the connective tissue in the "intertendon" of the muscle receptor organ correspond to the dendrite ramification; In this area, some muscle fibres end direktly at tendon-like connective tissue structures, but a number of different fibres run uninerruptedly through the whole muscular fascicle. 3. The perikaryon of every sensory neuron shows 2 "cytoplasm types" which are clearly distinguishable one against the other. A characteristic feature of the granular-lamellar neuroplasm that closely surrounds the nucleus are many flat vesicles of the granular endoplasmatic reticulum, accumulations of free ribosomes, numerous mitochondria and Golgi fields. The fibril-rich neuroplasm on the contrary contains only few mitochondria, but very many neurofilaments, here and there also neurotubuli. It projects directly into the dendrites and neuritek. Cell bodies, axon and dendrites are surrounded alternatingly by sheath cells and connective tissue of collagenous nature. The innermost layer of the coat cells borders directly on the neuron membrane. Finer dendrites are enclosed by nothing more but a thin layer of sheath cell plasm and intercellular substance. The dendrite terminals are either stored directly in connective tissue ground substance or border immediately on the sarcoplasm. 5. The axo-dendritic or axo-somatic synapses, respectively, contain numerous ellipsoidal (250-350 X 400-500 A), but also many spherical, vesicles. Some vesicles have a slightly larger diameter (700-900 A) and contain an electron-dense core. The synaptic gap measures 150 to 200 A. The neuromuscular (supposedly excitatory) synapses are filled much lighter with vesicles as compared with those just mentioned, which show a relatively unique form and size (nearly all spherical, phi 400-500 A). There are less vesicles with an electron-dense centre. On the average, the synaptic gap is broader (200-250 A) and the contact zone is larger. Apart from these, terminals could be observed in the dendritic ramification area, too, resembling the axo-dendritic and axo-somatic ones, respectively. 6. Finer dendrite branches contain vesicles differing slightly from those mentioned above as far as shape and size are concerned. Their diameters vary between 500 and 1 000 A. "Dense bodies" could be observed sporadically in these vesicles.

Animals↗
PubMed1975

[Expermental contribution on the genesis of arteriosclerosis caused by hypertension].

Autoradiographic tests carried out on rats with renal hypertension using 3H-proline resulted in an acclerated collagen synthesis by media cells of aorta and coronary arteries. Electronmicroscopically an increased content of collagen fibers and an enrichment of ruthenium-red-positive substances in the extracellular space were found. The 35S-sulfate-incorporation in aorta and coronary arteries of animals with hypertension is also increased. These changes in the extracellular space of the vascular wall have an atherosclerosis promoting effect, probably caused by a distrubance of the permeability.

Animals↗
PubMed1974

[Light and electron microscope investigation of axons and dendrites in the pars dorsalis of the corpus geniculatum laterale of the albino rat].

1. The neuronal elements of the GLD of the albinorat were investigated by Golgi-Kopsch and Golgi-Rapid methods. Furthermore the terminals of the tractus opticus were investigated by electron microscopy after eye enucleation. 2. The thalamo-cortical relay neurons have dendritic protrusions. These spine-like protrusions are to be found in the terminal parts of the dendrites. In contrast to spines in the pyramidal cells there is no thickening of the terminal part. Few relay cells have grape-like appendages in their branching zone. Only the initial segments of the axons of the P-neurons are visible. There is no evidence of recurrent collaterals. 3. The Golgi-type-2-neurons (interneurons, I-neurons) have less dendrites than the P neurons, but they are longer...

Animals↗