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Biomedical subjects

L Rechardt

Publications and source records attributed to L Rechardt.

At least 55 records · Page 3Linked to original sources
PubMed1983

Serotonin-like immunoreactivity in rat carotid body.

Serotonin-like immunofluorescence was demonstrated in the glomus cells of the rat carotid body. Similar immunoreactivity was noted in mast cells in the organ, while no immunoreactive nerve fibers were seen. It is suggested that glomus cell serotonin could participate in the modulation of chemoreceptor activity.

Animals↗
PubMed1983

Lesions of myocardial capillary vessels during open-heart surgery.

In a clinical series of patients undergoing open-heart surgery, capillary lesions in the myocardium were common when hypothermic chemical cardioplegia was used for myocardial protection during aortic cross-clamping. It seems obvious that the resulting oedematous swelling of the capillary wall, especially that of the endothelial cells, may constitute an anatomic intraluminal obstacle to myocardial reperfusion, thereby further delaying the recovery. After (mere) topical cooling, only minor capillary changes were observed. In contrast to the oedematous transformation described above for the former group, capillary endothelial cells and pericytes of the latter were diminished in cellular volume.

Capillaries↗
PubMed1983

Reinnervation of human skin grafts: a histochemical study.

The reinnervation of nine human skin grafts was investigated using histochemical thiocholine methods for the demonstration of cholinesterases. The regenerated cutaneous nerves showed both specific acetylcholinesterase and nonspecific cholinesterase reactions. In the youngest specimens, taken 3 weeks after the grafting, such regenerated nerves were seen both at the subdermal level under the graft and at the margins of the graft. These nerves seemed to orient toward the denervated graft area. The growing nerves were generally distributed in a random fashion. The reinnervation of some hair follicles, erector pili muscles, and sweat glands were observed in well-innervated full-thickness and thick partial-thickness skin grafts. It is suggested that this target-organ control of regenerating nerves occurs as a result of the action of chemotactic factors. A well-innervated graft bed seems to be important for optimum reinnervation of skin grafts. Fibrosis and scarring seem to hamper nerve regeneration.

Acetylcholinesterase↗
PubMed1983

Cardioplegia versus topical cooling for cardiac protection during open-heart surgery. An electron microscopic and histochemical study of right atrial biopsies.

The effectiveness of topical cooling and cold cardioplegia for cardiac protection in the course of open-heart surgery was studied by electron microscopy and fluorescence microscopy of right atrial biopsies. In 20 patients with topical cooling, no changes or minimal changes were observed in 15 cases, more pronounced changes in 3 cases, and severe destruction in 2 cases. In the group of 20 patients with cold cardioplegia the range of the changes was significantly narrower: no specimen remained completely intact; on the other hand, very severe destruction was not observed. Fluorescence microscopy revealed that the neural noradrenaline stores were relatively resistant to ischaemia. Electron microscopy showed certain failure of the protective procedure, resulting in injury of myocardial cells and neural elements. Even "spot-like" destruction noted in the nerve terminals may interfere with the peripheral neuro-neuronal interaction, resulting in nonhomogenous spread of the excitation wave front and electrical instability of the heart. Therefore cardiac nerve damage should also be taken into consideration when evaluating the effectiveness of different methods for cardiac protection.

Aortic Valve↗
PubMed1982

Ultrastructural changes in the neurohypophysis of the aged male rat.

The neurohypophyses (neural lobes of the pituitary) of young adult (3-6 months) and aged (12-30 months) male rats were studied by means of electron microscopy. Stereomorphometric analyses were performed to determine the size, number and relative volume of the hormone-containing vesicles. The principal observations included: 1) the conspicuous depletion in aged rats of the granular hormone-containing vesicles from the axon terminals and the Herring bodies, with a decrease in the relative volume fraction of the vesicles from 4.8 Vv% in the control animals to 1.1 Vv% in the aged rats; 2) a change in the size-distribution of the hormone vesicles; 3) an increase in the extracellular space around the nerve terminals, axons and capillaries; and 4) lipid accumulations and signs of activation in the pituicytes. The possible physiological significance of the findings is discussed in the light of several regulatory functions known to be altered during the process of ageing.

Aging↗
PubMed1982

Effect of norepinephrine, prenalterol and metoprolol on the histochemical localization of adenylate cyclase activity in the brown adipose tissue of newborn rat.

Norepinephrine-stimulated adenylate cyclase enzyme (EC 4.6.1.1.) was histochemically demonstrated by electron microscope in the plasmalemmas of the newborn rat adipocytes. The precipitating agent in the histochemical reaction was cobalt salt. Metoprolol, a selective beta 1-blocker given in vivo abolished almost totally the reaction products from the outer surfaces of the plasmalemmas. In vitro treatment did not yield constantly reproducible results. Prenalterol (H 133/22-CGP 7760/B Hässle) a selective beta-agonist given in vivo stimulated enzyme activity in the plasmalemmas. The reaction, however, showed different localization patterns and enhanced amounts of reaction products in the membranes. It is proposed that the histochemical demonstration of amine-stimulated adenylate cyclase activity in the adipocyte plasmalemmas corresponds to the hormonal receptor sites. The question of the sensitivity of the receptors is discussed.

Adenylyl Cyclases↗
PubMed1982

Synthesis and storage of hormonal granules in cultured cells of the rat pituitary pars intermedia.

Tissue from the pars intermedia of the pituitary from new-born and adult rats was maintained in tissue culture for periods up to 14 days. Both new-born and adult rat pars intermedia cells showed active production of secretory granules during tissue culture, and also showed formaldehyde-chloral induced fluorescence. Immunohistochemically, beta-endorphin could be demonstrated in cultured pars intermedia cells. In contrast to the appearance of the pars intermedia cells in vivo, the granules in the cultured cells were most often seen along the cell membrane, and the cytoplasm was often dominated by clear vacuoles slightly larger than the granules. No exocytotic figures were observed in the cultured cells. The mechanism of hormonal release from the organ, if release does occur, thus remains obscure. In conclusion, cultured cells from the rat pituitary pars intermedia continue their production of hormonal granules in tissue culture, and thus form a valuable tool for further investigations on the complex regulation of hormonal secretion form the organ.

Age Factors↗
PubMed1981

Glial uptake of monoamines in primary cultures of rat median raphe nucleus and cerebellum. A combined monoamine fluorescence and glial fibrillary acidic protein immunofluorescence study.

Glial uptake of serotonin and dopamine was studied in primary cultures of the median raphe nucleus and cerebellum by using consecutive demonstration of monoamine fluorescence and glial fibrillary acidic protein immunofluorescence. Most of the glial cells taking up monoamines were glial fibrillary acidic protein positive. Astrocytes with a strong immunoreactivity exhibited monoamine fluorescence only occasionally, although such cells did take up L-dopa readily. Glial fibrillary acidic protein negative cells--morphologically identified as astrocytes--were seen to exhibit monoamine fluorescence after exposure. Glial uptake of serotonin at a concentration of 10(-4) M was detected in cerebellar cultures but not in cultures from the median raphe nucleus. When the concentration was 10(-3) M uptake of serotonin took place in both the areas but was weaker in cultures from the median raphe nucleus. At concentrations greater than 10(-5) M glial uptake of dopamine was detected in cultures from both the regions studied. No region dependent differences in glial uptake of dopamine was demonstrated, however. Based on these observations astrocytes and astrocyte-like glial cells take up dopamine and serotonin. Also glial cells with a remarkably high content of the glial fibrillary acidic protein are more resistant to monoamine uptake than cells exhibiting less intense or no glial fibrillary acidic protein immunofluorescence. The existence of regional differences in uptake of serotonin between the median raphe nucleus and cerebellum suggests that glial uptake of monoamines is not an entirely passive mechanism but may be actively controlled by glial cells in a region dependent manner.

Animals↗
PubMed1980

Ultrastructural localization of acetylcholinesterase activity in primary cultures of rat substantia nigra.

Ultrastructural localization of acetylcholinesterase activity was studied in primary cultures of the substantia nigra microdissected from newborn rat brains. Light microscopic observations were also made on the characteristics of dopamine neurones and acetylcholinesterase containing cells in these cultures. Ultrastructurally acetylcholinesterase activity was localized in the nuclear envelope and rough endoplasmic reticulum of neurones, which had deeply infolded, round or oval nucleus, a prominent Golgi apparatus and varying amounts of rough endoplasmic reticulum. In the neuropil acetylcholinesterase activity was seen within microtubules of neuronal processes and in the rough endoplasmic reticulum of dendrites. The enzyme activity was also demonstrated within the nuclear envelope and rough endoplasmic reticulum of probably capillary endothelial cells. Dopaminergic neurones were identified on the basis of the green catecholamine fluorescence they exhibited. Small dopaminergic neurones could be observed and there was indirect evidence that these cells did not stain for acetylcholinesterase.

Acetylcholinesterase↗
PubMed1980

Ultrastructure of neurosecretosomes sedimented in the nuclear fraction from the posterior pituitary of the rat.

Subcellular fractions of the posterior pituitary of the rat were isolated by differential and density gradient centrifugation, and microsamples prepared for electron miscroscopy by KMnO4 or glutaraldehyde-OsO4 fixation. The nuclear fraction, P1 (1000 g x 7 min), was the main neurosecretosome (NSS) fraction and contained nuclei and mitochondria in addition to NSS (60%). The crude mitochondrial fraction, P2 (10,000 g x 20 min), contained free mitochondria (70%), NSS, unidentified membrane particles, fat droplets derived from pituicytes, neurosecretory granules (NSG) and synaptosomes, identified by the presence of synaptic membrane thickenings. Fraction P3 (32,900 g x 20 min) contained mainly free NSG, while fraction P4 (118,000 g x 30 min) had a high microsome content.

Animals↗
PubMed1980

Innervation of the human gastric wall.

The intrinsic innervation of the human gastric wall was studied by means of (1) demonstration of the acetylcholinesterase activity, (2) fluorescence microscopy, and (3) electron microscopy. The cholinergic innervation was rich: in the mucosa, a dense three dimensional network consisting of single delicate varicose acetylcholinesterase-positive axons and small nerve fascicles was observed in close relation to the gastric glands. In the submucosa, large nerve trunks and densely woven plexuses mainly consisting of single varicose axons (obviously perivascular plexuses)) were seen. In the muscularis external, a small-meshed net consisting of single varicose axons and nerve fascicles was observed. The ganglia of the myenteric plexus were small and scattered irregularly between and within the muscle layers. Most of the nerve cells exhibited moderate to intense acetylcholinesterase activity. In the serosa, only a few nerves were observed. By fluorescence microscopy, an abundance of brightly yellow fluorescing irregularly fusiform enterochromaffin cells was observed in the epithelial lining of the antral glands. The parietal cells of the fundic glands exhibited a granular, yellow to orange autofluorescence. Fluorescing axons were seen in intimate relation to some enterochromaffin cells, whereas most enterochromaffin cells and parietal cells did not receive any direct functional adrenergic innervation. In the other tissue layers, only a few fluorescing nerves were seen. The main ultrastructural characteristics of the intrinsic innervation of the mucosa were: (1) 'Innervation fasciculée'; (2) the axons were unmyelinated; (3) two main types of nerve terminals were identified according to their vesicle population(s): (a) nerve terminals containing only clear vesicles, (b) nerve terminals containing clear vesicles and large dense-cored vesicles. Most of the axons and nerve terminals within the nerve fascicles were acetylcholinesterase-positive. The nerve terminals were separated from the gastric glands (and the parietal cells, chief cells and endocrine cells of their epithelial lining) by a considerable gap so that it seems unlikely that the gastric glands, parietal cells, chief cells and endocrine cells receive a direct innervation in the sense of synaptic neurotransmission; the transmitter substance must diffuse across a wide gap. In contrast, the endocrine cells were in close contact with the parietal cells and chief cells, and occasional membrane specialization (desmosomes) reinforce the assumption that (also) direct local humoral interaction may be possible. In addition, a large number of mast cells was observed in the lamina propria, many lying as close to glandular cells (parietal cells, chief cells and endocrine cells) as were the nearest nerve terminals.

Acetylcholinesterase↗
PubMed1979

The development of histochemically demonstrable cholinesterases in the rat neostriatum in vivo and in vitro.

The development of acetylcholinesterase (AChE) and non-specific cholinesterase (NsChE) activity was studied in the rat neostriatum by the light and electron microscope using three thiocholine methods. The AChE activity was first demonstrable only in the lateral parts of the nucleus, and during the early postnatal development the most intense activity was in the cell bodies, whilst the typical intense staining of the neuropil of adult animals was seen in two-week-old rats. Two types of AChE-containing cells were observed in the neostriatum of rats younger than two weeks and in cultures of newborn rat neostriatal cells. The neuropil of the cultures showed weak activity in the membranes of thin preterminal processes. In the neuropil of old rats, NsChE activity was present in the membranes of nerve cell processes. The capillary endothelial cells of newborn rats contained both AChE and NsChE. During subsequent development, the AChE activity disappeared, whilst for NsChE no change was seen in the distribution of activity seen in newborn or young adult rats less than three months old.

Acetylcholinesterase↗