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Biomedical subjects

D Reimers

Publications and source records attributed to D Reimers.

At least 37 records · Page 2Linked to original sources
PubMed1989

Administration of bovine superoxide dismutase prevents sequelae of spinal cord ischemia in the rabbit.

The contribution of free radical-mediated reperfusion injury to the ischemic damage caused by total arterial occlusion has been investigated in a model of transient spinal cord ischemia in the rabbit. Spinal cord ischemia was produced in 20 anaesthetized rabbits by temporary luminal occlusion (20 min) of the abdominal aorta below the renal arteries. Superoxide dismutase (5 mg/kg) (10 animals) was infused before and during reperfusion below aortic occlusion using an infusion pump that infused the enzyme through the contralateral femoral artery. Control (10 animals) received sterile saline with the same procedure. In this later group, 4 animals developed paraplegia, 4 were paretic and only 2 were normal. However, in the treated group, 6 animals were normal while 3 were paretic and only one appeared paralyzed. We conclude that: a) oxygen free radicals generated during reperfusion are involved in producing the ischemic injury, and b) the ischemic spinal cord injury is prevented by superoxide dismutase.

Animals↗
PubMed1987

Adrenergic innervation of human middle cerebral artery. Ultrastructural observations.

The innervation of the human middle cerebral artery is studied with transmission electron microscopy using the chromaffin reaction technique. Adrenergic nerve fibers and related terminals, with granular electrodense neurotransmitter vesicles, are confined to the tunica adventitia-tunica media transitional zone and the outer layers of the media. These findings may indicate the presence of an adrenergic vasoconstrictor system for circulation control in the human middle cerebral artery.

Cerebral Arteries↗
PubMed1987

Intramembranous cytochemistry: a new morphological technique for studying cholesterol in the astrocyte plasma membrane of ischemic brain cells.

The distribution of cholesterol in the astrocytic plasma membranes of normal and ischemic caudate nucleus in the cat was investigated with the polyene antibiotic, filipin, a morphological probe for membrane cholesterol domains in freeze-fracture tissue replicas. After filipin incubation of prefixed vibratome slices, filipin-cholesterol complexes appeared as 20 to 30 nm protuberances and pits on P- and E-faces of the replicas. Distinct patterns of filipin-cholesterol complexes were found on nonischemic and ischemic astrocyte membranes. The filipin-treated specimens showed an 80% decrease in astroglial plasmalemma of cholesterol 1 hour after cerebral ischemia.

Animals↗
PubMed1985

Quantitative electron microscopic study of calcium accumulation in cerebral ischemia mitochondria.

Formation of calcium deposits in mitochondria is a consistent feature of irreversible injury in ischemic myocardium. We studied calcium accumulation in nerve cell mitochondria in a cat model 30 and 60 minutes after cerebral ischemia localized in the anterior part of the caudate nucleus and adjacent internal capsule. In control animals, calcium deposits were visible in synaptic vesicles, Golgi apparatus, mitochondria, lysosomes, and in glial and neuronal nuclei. After cerebral ischemia, findings included astrocytic swelling and degeneration of neurons, with an increase in calcium pyroantimoniate mitochondrial deposits. Content of intramitochondrial calcium deposits is related to duration of ischemia as well as the amount of cellular lesions.

Animals↗
PubMed1985

Intraluminal thrombus and neointimal hyperplasia after microvascular surgery.

Despite advances in instrumentation, suture materials, and techniques, thrombosis and intimal hyperplasia due to myointimal cell proliferation are still problems in microvascular anastomosis. Platelet factors stimulate smooth-muscle cell proliferation and migration, but little is known about platelet-vessel wall interaction in microvascular surgery. This study evaluates the effect of the disposition of platelet or luminal thrombus, or both, in intimal evolution in autologous venous micrografts interposed in the common carotid artery of 30 rats. Three hours postoperatively, venous graft and suture line endothelium was completely denuded, and the host artery exhibited focal de-endothelialization. Thrombus deposition was observed on suture line and venous graft luminal surfaces, whereas host artery-denuded areas exhibited platelet adhesion. Two weeks postoperatively, intimal thickenings developed in venous graft and suture line, becoming narrower toward the venous graft. The distribution and size of intimal thickening did not change significantly at later observation periods (3-8 months). Intimal thrombus deposition and intimal hyperplasia, appearing in later stages of evolution, show a similar pattern of distribution.

Animals↗
PubMed1985

Possible role of endothelium in the orientation of smooth muscle cells in experimental neointima.

Myointimal cells (MIC) orientation and intimal thickening evolution, induced by grafting an autogenous venous patch onto the rat common carotid artery, were studied with light microscopy at different times until 14 months after surgery. Intimal thickenings in the venous patch were most prominent at an intermediate postoperative period, after which their mean size did not change significantly. In host artery neointima, the greatest MIC proliferation was observed at a late stage of evolution. MIC arrangement was predominantly circumferential to the blood stream in venous patch neointima, whereas it was mostly axial in the host artery. The interaction between MIC orientation and endothelial regeneration in the operated vessel is discussed.

Animals↗
PubMed1984

Aspects of interastrocytic gap junctions in blood-brain barrier in the experimental penumbra area, revealed by transmission electron microscopy and freeze-fracture.

Interastrocytic gap junctions in the blood-brain barrier of the experimental penumbra area were studied in the cat caudate nucleus 1 h after ischemia. Transmission electron microscopy and freeze-fracture studies revealed only slight changes in gap junctions between astrocytes, indicating that these junctions are very resistant to hypoxia.

Animals↗
PubMed1984

Pericyte endothelial gap junctions in human cerebral capillaries.

Human cerebral tissue has been ultrastructurally studied and gap junctions have been visualized between endothelial cells and pericytes that permit ion exchange. We propose that the functional interrelationship between endothelium and pericytes may play a role in the alteration of capillary diameter for the control of local cerebral blood flow.

Blood-Brain Barrier↗
PubMed1984

Assemblies of intramembranous particles in astrocytoma: a preliminary report.

A human astrocytoma has been studied with the freeze-fracture technique. The astrocytic membrane presents many assemblies formed by aggregations of intramembranous particles (5.8-7.8 nm in diameter) in P-face arranged in a square, and complementary pit assemblies in E-face. In the interastrocytic gap junctions the connexions are packed in a crystalline array.

Astrocytoma↗
PubMed1982

Specific endothelial granules in venous patch neoendothelium in the rat.

Weibel-Palade bodies were observed in the neoendothelium and capillaries of vasa vasorum of autologous 'venous patches' grafted in the common carotid artery of the rat. These corpuscles varied in number and distribution but were most frequently found in the luminal area of endothelial cytoplasm. In venous patch neoendothelium, the shape, size and substructure of Weibel-Palade bodies were similar to those in other types of vascular endothelium. These specific endothelial granules were more numerous during the week following neoendothelium formation. It is proposed that these corpuscles may play a role in the proliferation of endothelial cells in venous patches.

Animals↗
PubMed1980

[Effects of rifampicin and streptomycin on the concentrations of testosterone and cortisol in the blood of men (author's transl)].

It has been shown previously that the biosynthesis and metabolism of oestrogens is affected by rifampicin. The present study was undertaken to investigate if rifampicin may also influence the plasma concentrations of testosterone and cortisol. Five male patients suffering from tuberculosis received rifampicin or streptomycin. During treatment with rifampicin testosterone concentrations were significantly elevated as compared to control conditions; this increase was found in the morning (8.00 h) as well as in the afternoon (16.30 h). When the same patients were treated with streptomycin, only irregular changes of testosterone concentrations were observed. The blood level of cortisol was increased in two patients, but unchanged in three patients who were treated with rifampicin. No changes at all were detected in patients under treatment with streptomycin. The results presented here show that rifampicin -- in contrast to streptomycin -- influences the biosynthesis of testosterone and possibly also that of cortisol.

Adult↗