Biomedical subjects

F Lauwers

Publications and source records attributed to F Lauwers.

28 records · Page 2Linked to original sources

PubMed1996

[The Internet in oral medicine and maxillofacial surgery].

The authors give an Internet short historical record, then describe the different services offered and the possible applications for oral and maxillo-facial surgery. Electronic-mail (E-mail) provides the ability to compose, send and receive messages through the computer and allows exchanging informations with colleagues around the world. Programs, files and graphics can be transferred from one computer to another. The "news groups" are interesting in various subjects and allow a team work. We find several hundred sites about maxillo-facial surgery. These sites present a medical department, diagnosis problems or therapeutic solutions, medical press. Any information submitted is insecure and could be observed by a third party while in transit. Internet potential (educational benefits, digital access to medical literature, online consultation service) is mentioned in the end of the article.

Communication↗

PubMed1996

[Occipital forehead pedicle for one-stage repair of defects of the upper third of the face].

The authors describe a reconstruction technique for defects of the superior third of the face using a fascio-cutaneous flap with a forehead paddle supplied by an occipital pedicle. This flap has been successfully used in three cases to cover defects of the temporo-zygomatic area indeed, the superior part of the cheek. Our three patients presented recurrent cutaneous carcinoma, a local and general poor condition. This process suits reliability and easiness to a good carcinologic, functional and aesthetic result.

Aged↗

PubMed1995

[The value of lidocaine-prilocaine cream in the surgery of detached ears].

The possibility to obtain a skin anaesthesia using only an ointment may be very usefull for outpatient surgery. Recently available in France, the lidocaine-prilocaine cream give an interesting local anaesthesia. We have used this new presentation as skin preparation before otoplasty for 10 patients. As the local anaesthesia injections are then performed without pain, the comfort of the patient is greatly improved. Furthermore, it is easy to sue and without side-effect. The main disadvantage consists in the action delay of one hour, with the necessity to ask the patient to come earlier.

Adolescent↗

PubMed1995

[Reconstruction of the orbit floor using a resorbable polydioxanone (PDS degree) cup. Analysis of a series of 71 cases].

A 71 patients series is presented, concerning primary orbital floor reconstruction by a polydioxanone cup (PDS degree) which has been used for five years. The technical data and surgical procedure are exposed. No infection either intolerance manifestation has been observed until the materiel was resorbed. Two early displacements of the implant are reported, due to a technical fault during the insertion of the cup. Only one late enophtalmy was observed for a patient with a large orbital floor defect. The loss a the rigidity of the polydioxanone seems to be relatively fast (probably 2-3 months) and leads to contraindicate its use in cases of large osseous traumatic defects. In all other cases, this surgical technique seems to be very useful.

Adolescent↗

PubMed1991

Oversensitivity to serotonin of the collateralized vascular bed in rat hindquarters: mechanisms of increased vasoconstriction.

A buffered solution was perfused at a constant flow rate (2 ml/min) through both iliac arteries in rat hindquarters. Perfusion pressures were measured in normal and collateralized vascular beds of the left and right hind-leg, respectively. Bolus injections of various agonists produced concentration-dependent increases in perfusion pressure in both collateralized and normal circulatory beds. Serotonin, in particular, and noradrenaline, to a lesser extent, produced more pronounced vasoconstriction on the collateral side than on the normal side. The difference in vasoreactivity to serotonin was related to a difference in both vascular structure and sensitivity of both types of vascular bed. Vasoconstriction induced by serotonin was inhibited by 5-HT2 antagonists. Selective blockade of alpha 1,alpha 2,beta 1-beta 2 adrenoceptors and amine uptake blockade were ineffective. This study indicates that, in rat hind-legs, the collateralized vascular bed is superreactive to serotonin in comparison with the normal bed. This resetting of reactivity to serotonin is due to the specific vascular structure as well as to an increased 5-HT2 receptor-mediated sensitivity.

Animals↗

PubMed1989

Ultrastructural evaluation of the effects of diclazuril on the endogenous stages of Eimeria maxima and E. brunetti in experimentally inoculated chickens.

The ultrastructural morphology of the different endogenous stages of Eimeria maxima and E. brunetti was evaluated after oral treatment of inoculated chickens with a single dose of 5 mg/kg diclazuril. The drug induced no ultrastructural change in the growth or differentiation of the various schizont stages of both Eimeria spp. In E. maxima, the micromorphological appearance of micro- and macrogamonts developing from the blast from to maturation also remained unaffected by drug treatment. However, in all fertilized macrogamonts the normal pattern of oocyst wall establishment was completely disturbed, resulting in the formation of an abnormally thickened, incomplete oocyst wall and the necrosis of the zygote. In E. brunetti, the growth and nuclear division during microgametogenesis were not affected but differentiation was clearly abnormal. In comparison with the controls, this abnormal differentiation was characterized by a less extensive enlargement of the parasite surface area, aberrant morphological configurations of condensed heterochromatin, intracytoplasmic flagella formation, and glycogen accumulation. Finally, the complete degeneration of all microgamonts ensued. The growth and differentiation leading to mature macrogamonts was not disturbed; however, subsequent oocyst wall formation was largely precluded and the macrogamonts proceeded to degenerate completely. We conclude that diclazuril treatment primarily affected particular stages in the sexual development of both Eimeria spp., resulting in the complete eradication of these coccidian species.

Animals↗

PubMed1989

Differential vasoreactivity to the thromboxane A2 mimic U-46619 of collateral and normal peripheral blood vessels in situ perfused rat hindquarters.

In situ perfusion of rat hindquarters was performed through both iliac arteries. Perfusion pressures were measured concomitantly in the normal vascular bed and in the ligation-induced collateral bed of the left and right hindleg, respectively. An increased vaso-constrictive response of the collateral versus normal blood vessels was found after bolus injections of increasing concentrations of the thromboxane A2 (TXA2) mimic U-46619. This increased reactivity was related to a difference in vascular structure and in receptor-mediated sensitivity. The vasoconstrictive effect of U-46619 was dose-dependently inhibited by the combined TXA2 synthetase inhibitor-TXA2/prostaglandin endoperoxide (PGH2) receptor antagonist ridogrel and the single TXA2/PGH2 receptor antagonist sulotroban. Selective blockade of alpha 1-, alpha 2-, beta 1-beta 2- and S2-receptors, cyclooxygenase inhibition, TXA2 synthesis inhibition, amine depletion and amine uptake blockade had no influence on the vasoconstrictive action of U-46619. Ca2+ entry blockade by flunarizine and nifedipine significantly reduced the vasoconstriction. This study shows that (1) rat peripheral collaterals in relation to normal arterial blood vessels are significantly more reactive to TXA2; (2) the vasoconstrictive effect of U-46619 is mediated predominantly by TXA2/PGH2 receptors; (3) the activation of these receptors elicits indirectly transmembrane Ca2+ entry to trigger vasoconstriction.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1988

In vivo action of the anticoccidial diclazuril (Clinacox) on the developmental stages of Eimeria tenella: an ultrastructural evaluation.

A single 5-mg/kg oral dose of diclazuril affected both the asexual and sexual development of Eimeria tenella in experimentally inoculated chickens. In second-generation schizonts, early growth and nuclear divisions progressed normally, but a marked inhibition of merozoite formation was observed. Exogenesis of merozoites was largely prevented, whereas production of micronemes, amylopectin granules, and dense bodies and the formation of rhoptries, conoid, and pellicle continued. All these subcellular organelles accumulated, together with differentiated nuclei, within the main cytoplasmic mass. In the end, complete necrosis of the schizonts occurred. In macrogamonts, dilation of the rough endoplasmic reticulum around type II wall-forming bodies, fusion of type II wall-forming body contents, disturbance of the normal parallel arrangement of rough endoplasmic reticulum, and disruption of row formation of amylopectin granules became evident. In the microgamonts, normal evagination of microgametes was prevented; the flagellar complex formed within the main cytoplasmic mass and the differentiated nuclei remained present within the parasite body. The macro- and microgamonts also ended up in a stage of complete necrosis. These data indicate that diclazuril treatment primarily affects the normal differentiation of the respective endogenous stages during parasite development. This leads to complete degeneration of schizonts and gamonts indicating the lethal effect of this new anticoccidial compound.

Animals↗

PubMed1987

Radioactive colloidal gold as a tool to quantify extravasation of macromolecules in the rat cremaster muscle.

Since previously described simple methods were too insensitive to quantify the extent of microvascular permeability increase in the rat cremaster muscle, we applied a new quantitative technique using radioactive colloidal gold (198Au) as the macromolecular tracer. Dose-response effects on microvascular permeability were found with increasing doses of subscrotally injected serotonin or histamine. The presence of colloidal gold particles in the subendothelial space of the postcapillary venules, as verified ultrastructurally, indicated endothelial permeation of the tracer macromolecules. The increased permeability elicited by serotonin was inhibited in a dose-dependent way by serotonin receptor antagonists (potency: methysergide greater than or equal to ketanserin = ritanserin greater than cinanserin), suggesting the presence of functional S2-serotonergic receptors on postcapillary venular endothelial cells. A dose-related inhibition of the histamine-induced extravasation was seen with the H1 antagonists astemizole and azatidine (astemizole greater than azatidine); the H2 antagonists cimetidine and ranitidine had no inhibitory effect. The radioactive colloidal gold technique is a sensitive and reliable tool for pharmacological experiments aimed at investigating the extravasation phenomenon in small tissue samples such as the rat cremaster muscle.

Animals↗

PubMed1984

Serotonin-induced blood flow changes in the rat hindlegs after unilateral ligation of the femoral artery. Inhibition by the S2 receptor antagonist ketanserin.

Collateral arteries can clearly be visualized in corrosion cast material after ligation of the femoral artery in rats. To characterize the influence of serotonin on the blood circulation under the experimental condition of unilateral ligation, we performed intermuscular thermoflow measurements. The data showed that intraperitoneal serotonin (8.7 and 20 mg.kg-1) injection markedly reduced the muscle temperature in both hindlegs. However, the effect was significantly more pronounced on the ligated side, where the blood was supplied through a collateral circulation, than on the non-ligated side with its normal arterial vasculature. Almost identical changes were obtained in rats with an early as well as in animals with a more advanced stage of collateral development (challenge with 8.7 mg.kg-1 serotonin). Evans blue dye experiments and angiographic data further revealed that, after challenge with 20 mg.kg-1 serotonin, the severe temperature decrease at the ligated side probably reflected a nearly complete blockage of blood supply. Pretreatment with the S2 receptor antagonist ketanserin (2.5 mg.kg-1) resulted in a significant reduction in the extent and duration of the serotonin-induced temperature decrease as revealed by the temperature measurements; such a treatment inhibited also the blockage in blood flow as seen with the other techniques. This study shows that serotonin, through its vasoconstrictive properties, can restrict the blood flow to the lower extremities of the rat, particularly when the blood is supplied through collateral circulation. This probably results in moderate to severe skeletal muscle ischaemia. It also suggests that the vasoconstriction is not only important in the inhibition of collateral blood flow in recently established collaterals but also in collateral vessels in a more advanced stage of development. The in vivo vasoconstriction and subsequent reduction of the blood supply caused by serotonin can be effectively counteracted by pretreatment with ketanserin.

Angiography↗