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Biomedical subjects

M Braun

Publications and source records attributed to M Braun.

At least 217 records · Page 12Linked to original sources
PubMed1994

Antiplatelet effects of ticlopidine are reduced in experimental hypercholesterolemia.

This study determines the antiplatelet effects of oral ticlopidine (100 mg/kg x day) in experimental hypercholesterolemia. Rabbits were fed either a standard diet or a cholesterol-enriched diet (0.5% for 3 months, 1% for 1 month). In normocholesterolemic controls ADP-, but not collagen-induced platelet aggregation was inhibited by ticlopidine treatment. This was accompanied by a significantly enhanced inhibition of ADP-induced platelet aggregation and stimulation of cyclic AMP accumulation by iloprost. Hypercholesterolemia considerably attenuated the inhibition of ADP-induced aggregation by ticlopidine but did not change its effect on the iloprost-induced inhibition of platelet function and cyclic AMP formation. ADP-induced platelet-derived thromboxane formation was considerably greater in hypercholesterolemic rabbits and not reduced by ticlopidine. Ticlopidine did also not significantly influence the extent and severity of atherosclerotic plaque formation although a tendency for improvement was observed in a subgroup of animals. The data suggest that hypercholesterolemia attenuates the inhibitory effect of ticlopidine on ADP-induced platelet aggregation. This might be related to the stimulation of thromboxane formation by ADP in hypercholesterolemia. The maintained protection from ADP-induced inhibition of cAMP accumulation suggests a minor role of this mechanism in the progression of hypercholesterolemia-induced vessel disease in this model.

Adenosine Diphosphate↗
PubMed1994

[Lumbar intervertebral disk. Structure. Knowledge status].

The purpose of this paper is to review the main data on the structure of the intervertebral disc, which are illustrated by personal documents. Applications in understanding the degenerative pathology are highlighted. The nucleus pulposus is the "central" component of the disc, highly hydrophilic, deformable but remaining of constant volume. It can be compared to a hydraulic chamber within the disc, sealed by the annulus fibrosus, which is a dense peripheric ring of concentric fibrous lamellae. The cartilaginous end plates (cranial and caudal) separate the disc from the adjacent subchondral vertebral bone. (Their involvement in the discal metabolism as well as the blood supply of the disc are developed elsewhere (see our companion article)).

Cartilage↗
PubMed1994

[Lumbar intervertebral disk. Intervertebral disk-vertebral body pathways and discal vascularization].

We studied the disco-vertebral interface and the blood supply of the intervertebral disks L3-L4, L4-L5, and L5-S1 of 5 human adult columns. Moreover, in order to investigate the discal vasculature, infusion of Japanese ink was used in 2 other adult columns, as well as immuno-histological methods in the L5-S1 disk of 4 adults and 2 infants. Our study confirms the paucity of discal vasculature in adults, by contrast with that of infants, but shows numerous defects in the subchondral vertebral plate, which are filled by vascularised medullary soft tissue and are in contact with the cartilaginous discal end plate. By these contacts, nutrients could reach the intervertebral disk, as suggested by other works, and as is the case in other cartilaginous structures of the body.

Humans↗
PubMed1994

Present status of computerized tomography and angiography in the diagnosis of cerebral thrombophlebitis cavernous sinus thrombosis excluded.

In order to evaluate the contribution of computerized tomography (CT) to the diagnosis of cerebral thrombophlebitis, a series of 28 cases was reviewed and compared with data from the literature. In an examination carried out 4 to 5 days of its constitution the thrombus may be directly visualized as a spontaneous hyperdensity. This early but very transient sign, called "cord sign", can easily be overlooked, which explains why it was found in only 5 of our 28 cases and in 2% of the largest series of the literature. The thrombus thereafter becomes hypodense and can be intensified by peripheral contrast enhancement which produces the classical "delta sign". This sign is more frequent: 13/28 in our series and 16 to 30% in published cases. It is usually found in the superior sagittal sinus and must be distinguished from anatomical variations which are common at that level. These two direct signs acquire a greater value when associated with such indirect signs as diffuse or localized cerebral oedema (12 to 52%) and venous ischaemia (22 to 59%). Venous ischaemia is characterized by its strong bleeding potential (more than 50% of the cases) and by its usually favourable course; these two elements and its site differentiate it from arterial ischaemia. Finally, venous stasis is responsible, in 5 to 19% of the cases, for intense enhancement of the tentorium cerebelli; this sign is not specific but easy to evidence and of great value when associated with a direct sign. Dilatation of cortical veins, found in 4 of our 28 cases, also seems to be an interesting sign which, to our knowledge, has not yet been mentioned in the literature. Since in 3.6 to 26% of the cerebral thrombophlebitis the CT scan is normal, a negative CT examination does not rule out this disease, and in many cases the exploration must be rapidly completed by angiography or MRI. Because it is non-invasive and very sensitive to flows, MRI has become the key examination to assert the diagnosis. Angiography is now restricted to those cases where cases where MRI cannot be performed promptly or to certain, purely cortical thrombophlebitis which might pass unnoticed at MRI. When carried out and interpreted cautiously, angiography always shows the venous thrombosis, its exact size and its suppletive network. The results of this study show that MRI alone can diagnose cerebral thrombophlebitis in most patients, that CT well done and interpreted often provides useful but seldom sufficient indices, and that angiography should be reserved for difficult cases.

Cavernous Sinus↗
PubMed1994

Role of the microtubule cytoskeleton in gravisensing Chara rhizoids.

The arrangement of the microtubule cytoskeleton in tip-growing and gravisensing Chara rhizoids has been documented by immunofluorescence microscopy. Predominantly axially oriented undulating bundles of cortical microtubules were found in the basal zone of the rhizoids and colocalized with the microfilament bundles underlying the cytoplasmic streaming. Microtubules penetrate the subapical zone, forming a three-dimensional network that envelops the nucleus and organelles. Microtubules are present up to 5 to 10 microns basal from the apical cytoplasmic region containing the statoliths. No microtubules were found in the apical zone of the rhizoid which is the site of tip growth and gravitropism. Depolymerization of microtubules by application of oryzalin does not affect cytoplasmic streaming and gravitropic growth until the relatively stationary and polarly organized apical and subapical cytoplasm is converted into streaming cytoplasm. When the statoliths and the apical cytoplasm are included in the cytoplasmic streaming, tip growth and gravitropism are stopped. Oryzalin-induced disruption of the microtubule cytoskeleton also results in a rearrangement of the dense network of apical and subapical microfilaments into thicker bundles, whereas disruption of the microfilament cytoskeleton by cytochalasin D had no effect on the organization of the microtubule cytoskeleton. It is, therefore, concluded that the arrangement of microtubules is essential for the polar cytoplasmic zonation and the functionally polar organization of the actin cytoskeleton which is responsible for the motile processes in rhizoids. Microtubules are not involved in the primary events of gravitropism in Chara rhizoids.

Chlorophyta↗
PubMed1994

[Rhinorrhea and otorrhea: rare complications of the medical treatment in invasive prolactinomas].

Cerebrospinal fluid rhinorrhea and otorrhea are rare complications of conservative and medical management of invasive macroprolactinomas. The slow shrinkage of the tumor during therapy is responsible for delayed rhinorrhea and otorrhea which carry the risk of meningitis. The operative procedure for closure of the fistulae is needed. We report the occurrence of CSF rhinorrhea in two patients with macroprolactinoma who were treated by bromocriptine. In one patient the fistulae is surgically treated and the treatment by bromocriptine is maintained. In the other patient the rhinorrhea is associated with otorrhea and the operation is not required because of the massive destruction of skull base. The CSF rhinorrhea and otorrhea stopped after diminution of bromocriptine doses.

Adult↗
PubMed1993

Statoliths pull on microfilaments: experiments under microgravity.

Previous videomicroscopy of Chara rhizoids during parabolic flights of rockets showed that the weightless statoliths moved basipetally. A hypothesis was offered that the removal of gravity force disturbed the initial balance between this force and the basipetally acting forces generated in a dynamic interaction of statoliths with microfilaments (MFs). The prediction of this hypothesis that the statoliths would not be displaced basipetally during the microgravity phase (MG-phase) after disorganizing the MFs was tested by videomicroscopy of a rhizoid treated with cytochalasin D (CD) immediately before the flight. The prediction was fully supported by the flight experiment. Additionally, by chemical fixation of many rhizoids at the end of the MG-phase it was shown that all rhizoids treated with CD before the flight had statoliths at the same location. i.e., sedimented an the apical cell wall, while all untreated rhizoids had statoliths considerably displaced basipetally from their normal position. Thus, a dynamical interaction involving shearing forces between MFs and statoliths appears highly probable.

Actin Cytoskeleton↗
PubMed1993

Centrifugation causes adaptation of microfilaments: studies on the transport of statoliths in gravity sensing Chara rhizoids.

The actin cytoskeleton is involved in the positioning of statoliths in tip growing Chara rhizoids. The balance between the acropetally acting gravity force and the basipetally acting net outcome of cytoskeletal force results in the dynamically stable position of the statoliths 10-30 micrometers above the cell tip. A change of the direction and/or the amount of one of these forces in a vertically growing rhizoid results in a dislocation of statoliths. Centrifugation was used as a tool to study the characteristics of the interaction between statoliths and microfilaments (MFs). Acropetal and basipetal accelerations up to 6.5 g were applied with the newly constructed slow-rotating-centrifuge-microscope (NIZEMI). Higher accelerations were applied by means of a conventional centrifuge, namely acropetally 10-200 g and basipetally 10-70 g. During acropetal accelerations (1.4-6g), statoliths were displaced to a new stable position nearer to the cell vertex (12-6.5 micrometers distance to the apical cell wall, respectively), but they did not sediment on the apical cell wall. The original position of the statoliths was reestablished within 30 s after centrifugation. Sedimentation of statoliths and reduction of the growth rates of the rhizoids were observed during acropetal accelerations higher than 50 g. When not only the amount but also the direction of the acceleration were changed in comparison to the natural condition, i.e., during basipetal accelerations (1.0-6.5 g), statoliths were displaced into the subapical zone (up to 90 micrometers distance to the apical cell wall); after 15-20 min the retransport of statoliths to the apex against the direction of acceleration started. Finally, the natural position in the tip was reestablished against the direction of continuous centrifugation. Retransport was observed during accelerations up to 70 g. Under the 1 g condition that followed the retransported statoliths showed an up to 5-fold increase in sedimentation time onto the lateral cell wall when placed horizontally. During basipetal centrifugations > or = 70 g all statoliths entered the basal vacuolar part of the rhizoid where they were cotransported in the streaming cytoplasm. It is concluded that the MF system is able to adapt to higher mass accelerations and that the MF system of the polarly growing rhizoid is polarly organized.

Acceleration↗
PubMed1993

Antiatherosclerotic effects of oral cicaprost in experimental hypercholesterolemia in rabbits.

The efficacy of the oral prostacyclin mimetic cicaprost in preventing atheromatous plaque formation was studied in an in vivo model of experimental hypercholesterolemia. New Zealand white rabbits were fed either standard chow or a cholesterol-enriched (1%) diet for 12 weeks. Cicaprost was added to the drinking water in a non-hypotensive dose (5 micrograms/kg/day) and withdrawn 3 days prior to studying platelet, leukocyte and endothelial function. In cholesterol-fed rabbits, oral cicaprost reduced the aortic intimal surface covered by atheromatous lesions from 84 to 63% (P < 0.05). There was no major difference in serum lipid composition between cicaprost- and vehicle-treated animals. In hyper-cholesterolemic rabbits there was a significant impairment of endothelium-dependent relaxations. Cicaprost treatment considerably improved this endothelial function but had no effect in rabbits receiving standard diet. In addition, platelet and leukocyte hyperreactivity, as seen in hypercholesterolemic rabbits, were largely reduced by cicaprost treatment. These data are the first to demonstrate marked antiatherosclerotic effects of long-term oral prostacyclin treatment. The mechanism may be related to improved endothelial function and subsequent prevention of secondary platelet and neutrophil hyperreactivity.

Acetylcholine↗
PubMed1993

[A case of human sparganosis in Argentina].

A male patient from Peru presented a nodule localized in the left costal region. All other clinical and laboratory data were normal. Upon biopsy, an helminth parasite emerged from the subcutaneous tissue, which presented a marked eosinophil infiltrate. The helminth was classified as a plerocercoid larva of Spirometra; the species was not determined. Since Spirometra are not common in Argentina, it is presumed that the patient was infested during his two year sojourn in the peruvian forest. Some epidemiological aspects are discussed. As far as we know, this is the first case of subcutaneous sparganosis and the second of sparganosis reported in Argentina.

Adult↗
PubMed1993

[An original technique of reconstruction of the cricoid cartilage by vitalized scapular flap. Application to pharyngolaryngeal carcinology].

A personal technique for cricoid reconstructive surgery is presented and discussed. A transfert of a free living scapular flap by microvascular anastomoses is used for reconstructing half cricoid resection. We can with this technique increase the number of partial laryngectomy in patients with squamous cell carcinoma. Two techniques are possible: The half anterior laryngectomy conserves only the half posterior cricoid and the twice arytenoids. The half lateral laryngectomy conserves one arytenoid and a half cricoid.

Cricoid Cartilage↗
PubMed1993

[Acquired benign myofibroma of the skin (adult myofibroma)].

Adult myofibroma is an acquired skin tumour that is histologically identical to infantile myofibroma. Histologically, four tumour variants can be distinguished: leiomyoma type, cellular spindle cell type, haemangiopericytoma or glomus type, and biphasic type. Practical help in diagnosis is supplied by the hamartomatous composition of the leiomyoma-type, hyalinized spindle cell whorls, endothelium-lined haemangiopericytoma-like vascular channels, and desmin-negative, muscle-actin-positive myofibroblasts, which may show spindle cell or undifferentiated mesenchymal cell differentiation. The tumours clinically present as firm, occasionally bluish cutaneous or subcutaneous nodules. Adult myofibroma should be recognized as a distinct benign neoplasm, most probably of vascular origin. Clinicians and dermatopathologists must be aware that lesions identical to those of infantile myofibroma can occur in adults.

Adolescent↗