Biomedical subjects

E Simon

Publications and source records attributed to E Simon.

At least 55 records · Page 3Linked to original sources

PubMed2000

Activation of EphA2 kinase suppresses integrin function and causes focal-adhesion-kinase dephosphorylation.

Interactions between receptor tyrosine kinases of the Eph family and their ligands, ephrins, are implicated in establishment of organ boundaries and repulsive guidance of cell migration during development, but the mechanisms by which this is achieved are unclear. Here we show that activation of endogenous EphA2 kinase induces an inactive conformation of integrins and inhibits cell spreading, migration and integrin-mediated adhesion. Moreover, EphA2 is constitutively associated with focal-adhesion kinase (FAK) in resting cells. Within one minute after stimulation of EphA2 with its ligand, ephrin-A1, the protein tyrosine phosphatase SHP2 is recruited to EphA2; this is followed by dephosphorylation of FAK and paxillin, and dissociation of the FAK-EphA2 complex. We conclude that Eph kinases mediate some of their functions by negatively regulating integrins and FAK.

3T3 Cells↗

PubMed2000

[Facial bone reconstruction. Review of particularities and procedures].

The authors report the particularities of the cranio-maxillofacial skeleton and the aims of the reconstruction procedures: osteogenesis, osteoconduction, osteoinduction. They review the various procedures, their abilities, some technical notes, their advantages and disadvantages. They analyse in order: classical bone autografts, pedicled bone flaps (arterio-osseous, fascio-osseous, myo-osseous flaps), free bone flaps, classical and pedicled periosteal transplantations. They also describe the mechanical and biological procedures of bone stimulation: bone distraction, guided bone regeneration, bone growth factors, and the biomaterials, especially coral and enosseous implants. They conclude that, in facial reconstruction, the best material is the autologous bone membranous and vascularized.

Bone Transplantation↗

PubMed1999

Pharmacological characterisation of amylin-related peptides activating subfornical organ neurones.

Amylin, calcitonin gene-related peptide (CGRP) and calcitonin are structurally related peptides with overlapping peripheral and central actions. Amylin and calcitonin excite the majority of neurones in the subfornical organ (SFO), where high densities of so-called C-type G-protein-coupled receptors have been detected. Subcutaneous injection of these hormones stimulates drinking similar to angiotensin II (ANGII), a dipsogen acting via the SFO. We now show that in addition to amylin and rat calcitonin (rCT), CGRP and salmon calcitonin (sCT) also excite SFO neurones. In extracellular recordings of an in vitro slice preparation of the SFO, 78% of all neurones (n=31) superfused with CGRP (10(-6) M) were excited. The excitatory effect was dose-dependent and reversible with an average threshold concentration of 5x10(-7) M, which is approximately 15-fold higher than reported for amylin-induced excitations. sCT (10(-7) M), which behaves as a non-competitive agonist at amylin as well as calcitonin receptors, caused irreversible excitatory responses in 96% of all recordings (n=26). Amylin-, CRGP- and rCT-induced excitations could be blocked by the selective amylin receptor antagonist AC187 (10(-5) to 10(-6) M), whereas sCT-induced excitations were not inhibited. The receptor antagonist human CGRP(8-37) (10(-6) M) partly caused agonistic responses, but did not block CGRP-induced excitations. The pharmacological profile observed in the present work, and in a recent publication using the same preparation, indicating (1) that CGRP is a weaker agonist in the SFO than amylin, (2) that sCT excites SFO neurones, and (3) that responses are blocked by AC187 but not by CGRP(8-37), is inconsistent with activation via CGRP receptors, but is instead consistent with involvement of amylin (C3) and calcitonin (C1) receptors, which are co-localized to a high degree on the same subset of SFO-neurones. We propose that it is unlikely that blood-borne CGRP has a significant effect on neurones in the SFO.

Amyloid↗

PubMed1999

[Femoral neck fracture complicating algodystrophy in pregnancy].

BACKGROUND: Sympathetic reflex dystrophy is an uncommon cause of pelvic pain not to be overlooked in pregnant women. CASE REPORT: At 8 months pregnancy, a 27-year-old woman complained of invalidating pain of the left hip. Magnetic resonance imaging of the pelvis performed the day after delivery evidenced a non-displaced fracture of the femoral neck and a typical aspect of sympathetic reflex dystrophy. DISCUSSION: The true frequency of sympathetic reflex dystrophy during pregnancy is probably underestimated. Approximately one hundred cases have been reported. The hip joint is involved in 9 out of 10 cases. Such localizations are uncommon outside pregnancy, accounting for 14 to 17% of all cases.

Adult↗

PubMed1999

Surface corrosion of dental ceramics in vitro.

The objective of this study was to evaluate possible structural surface changes in different dental ceramic materials in a provocative corrosive environment in vitro. On the basis of compositional and microstructural differences, seven dental ceramic materials were selected for the test. After sintering and autoglazing, the surface roughness of the specimens was evaluated by confocal laser profilometry. A specially designed specimen holder made it possible to locate the same surface area before and after contact with the corrosive solution. The surface topography was additionally analysed using scanning electron microscopy. All the ceramic materials displayed evidence of surface structural changes on the exposed surfaces, but to varying degrees. Traditional leucite-containing feldspathic porcelains displayed an increase in surface roughness compared with baseline conditions when kept in 4% acetic acid at 80 degrees C for 18 h. Micro-crystalline and non-crystalline ceramic materials, on the other hand, demonstrated a smoother surface or just a minor increase in surface roughness. Whether or not the smoother post-corrosion appearance of certain ceramic materials is indicative of a true increase in corrosion resistance or is merely the result of an uniformly progressive corrosive process will be the object of future studies.

Ceramics↗

PubMed1999

Cranio-facial fibrous dysplasia in a 38-year-old African woman: a case history.

A 38-year-old woman sought treatment with cranio-facial dysplasia involving the cranium, maxilla and the mandible. Her chief complaint was a mandibular swelling, which had appeared about 2 years previously, had gradually enlarged, and was associated with spontaneous pain. X-ray film examination revealed a ground-glass opacity with blurred demarcation and a 99 Tc medronate bone scan disclosed an increase in tracer uptake in the cranium, maxilla and mandible. The rest of the skeleton was not affected. Histological examination of the lesions revealed solid proliferation of spindle-shaped cells associated with islands of osteid and bone trabecullae with Chinese letter pattern and numerous multinucleated giant cells consistent with fibrous dysplasia. The continued osteoblastic activity of involved bones, coupled with the medical condition of the patient, restricted the management of the patient to largely supportive and palliative care.

Adult↗

PubMed1999

National oral health survey Zimbabwe 1995: dental caries situation.

Ten years after completion of the first national oral health survey, the second such survey was carried out in 1995. Application of a multi-stage sampling procedure resulted in 3,709 persons being examined according to the WHO oral health assessment form and criteria. The background variables studied were age, gender, type of location, socio-economic status. Comparison with results from major studies in other African nations are presented. It was concluded that the prevalence of dental caries in all age groups was high but that the severity was low. The prevalence of unmet treatment needs was very high with extraction as the predominant mode of treatment. The survey has shown that the vast majority of Zimbabweans are not receiving and/or are not seeking oral care.

Adolescent↗

PubMed1999

National oral health survey Zimbabwe 1995: periodontal conditions.

Ten years after completion of the first national oral health survey, a second national oral health survey was carried out in 1995. Application of a multi-stage sampling procedure resulted in 3,709 persons being examined. WHO's oral health assessment form and CPITN index was used. The background variables studied were age (15-19, and 35-44-year olds), gender, type of location, socio-economic status and level of education. Results suggest that the periodontal health of adolescents was better in 1985 than in 1995. Overall, the prevalence of periodontal conditions in both age groups was high but its severity was low. The need for complex periodontal treatment was only 4 per cent for adults. The survey has shown that the vast majority of Zimbabweans are not receiving and/or are not seeking periodontal care.

Adolescent↗

PubMed1999

Neuronal actions of oxytocin on the subfornical organ of male rats.

The aim of this study was to investigate effects of oxytocin (OT) on electrical neuronal activities in rat subfornical organ (SFO) and compare its action with the well-described excitatory effects of blood-borne angiotensin II (ANG II) on the same SFO neurons. With the use of extracellular recordings from spontaneously active neurons in slice preparations of the SFO of male rats, 11.7% of tested neurons (n = 206) were excited and 9.7% were inhibited by superfusion with 10(-6) M OT. Both excitatory and inhibitory effects of OT were dose dependent with similar threshold concentrations and were blocked by a specific OT-receptor antagonist but not by a vasopressin receptor antagonist. Blocking synaptic transmission with low calcium medium suppressed only inhibitory effects of OT. All but one of the OT-sensitive neurons were also excited by superfusion with ANG II at a concentration much lower than required for OT, suggesting that synaptically released OT rather than blood-borne OT alters the activity of SFO neurons in vivo. The results support the hypothesis that neurally released OT may modulate SFO-mediated functions by acting on OT-sensitive neurons.

Angiotensin II↗

PubMed1999

Heat acclimation and hypohydration: involvement of central angiotensin II receptors in thermoregulation.

This investigation attempted to confirm the involvement of central ANG II-ergic signals in thermoregulation. Experiments were conducted on rats undergoing short (STHA)- and long (LTHA)-term heat acclimation, with and without superimposed hypohydration. Vasodilatation (VTsh) and salivation (STsh) temperature thresholds, tail blood flow, and heat endurance were measured in conscious rats during heat stress (40 degrees C) before and after losartan (Los), an ANG II AT(1)-selective receptor antagonist, administration either to the lateral ventricle or intravenously. Heat acclimation alone resulted in decreased VTsh. STsh decreased during STHA and resumed the preacclimation value, together with markedly increased heat endurance on LTHA. Hypohydration did not affect this biphasic response, although STsh was elevated in all groups. The enhanced heat endurance attained by LTHA was blunted. Neither Los treatment affected the nonacclimated rats. In the heat-acclimated, euhydrated rats, intracerebroventricular Los resulted in decreased VTsh, whereas intravenous Los resulted in elevated STsh. Both intracerebroventricular and intravenous Los led to markedly enhanced heat endurance of the LTHA hypohydrated rats. It is concluded that the LTHA group showed a loss of the benefits acquired by acclimation on hypohydration, whereas the STHA rats, which show an accelerated autonomic excitability in that phase, gained some benefit. It is suggested that ANG II modulates thermoregulation in conditions of chronic adjustments. Central ANG II signals may lead to VTsh upshift, whereas circumventricular structures, activated via circulating ANG II, decrease STsh. On hypohydration these responses seem to be desensitized.

Acclimatization↗

PubMed1999

Thermoregulation as a switchboard of autonomic nervous and endocrine control.

Analyzing the multiple effectors of autonomic temperature regulation has, sometimes unexpectedly, provided insights into the characteristics according to which the non-thermoregulatory functions of these effectors are controlled. This article reviews the sympathetic control of cardiovascular and immune functions, hormonal control of energy balance and neurohormonal control of salt and fluid balance inasmuch as they are challenged by competing demands of thermoregulatory requirements. These interactions are taken as examples for the analytical power of the experimental conception to challenge non-thermoregulatory control systems with thermoregulatory activation, and vice versa. Animal models carrying spontaneous or intentionally produced gene defects and molecular and histochemical techniques of gene identification and neuronal tracing are becoming increasingly important. They are applied, in connection with physiological studies exploiting mutual interactions of autonomic control systems, with the aim to elucidate the cytoarchitecture of neuronal circuits by which specific autonomic regulatory activities are controlled.

Animals↗

PubMed1999

[Status of problems with administration of hormonal contraceptives].

Following the application of oral hormonal contraceptives situations may occur which need fast clarification. In this report we discuss the practical aspects of forgetting to take hormonal contraceptives, the risk for birth defects, the time when to restart taking oral contraceptives after delivery and abortion, the indications for stopping the application, the taking of oral contraceptives under anticoagulant therapy, the behaviour during migraine, the raising need of ethinylestradiol in the case of epilepsy, the procedure in case of oligophrenia, the prevention of the rheumatoid arthritis as well as special questions in cases of diabetes mellitus and gestational diabetes.

Contraceptives, Oral, Hormonal↗

PubMed1999

Cervico-facial necrotising fasciitis occurring with facial paralysis: case report.

Necrotising fasciitis is a soft tissue infection, usually polymicrobial, characterised by necrosis of fascia and subcutaneous tissue. It frequently involves the groin, abdomen and extremities, but rarely involves the cervico-facial region. A case is presented of a 70-year old man who, following a futile attempt to extract a lower left first molar, developed a cervico-facial necrotising faciitis with facial nerve paralysis. Bacteriological investigations revealed the presence of Klebsiella spp and viridans streptococci. It is emphasized that early detection of this disease followed by aggressive surgical debridement and antibiotic therapy are most important.

Aged↗

PubMed1999

Laparoscopic cholecystectomy in acute cholecystitis.

The authors retrospective analyze the role of golden standard laparoscopic cholecystectomy for the treatment of acute cholecystitis. They make a comparison between the results of 50 early cholecystectomy and 44 "a froid" cholecystectomy (operation was postponed until 6 weeks after acute cholecystitis had healed). From January 1997 to December 1998 536 laparoscopic cholecystectomies were performed. In 491 cases (91.6%) laparoscopic, and in 45 cases (8.4%) traditional (opening) method was indicated. Converted cholecystectomies were in 36 cases (7.3%). Agreeing to the literature they can determine the optimal timing of the operation in 72 hours from the onset of acute cholecystitis [2, 4]. In this group (first group) there were 50 cases, with 14 conversions (28%). In the second group (postponed, so called "a froid" phase) there were 44 patients. From this group was the intraoperative diagnosis serious acute-subacute cholecystitis in 24 cases (54.54%) causing complicated laparoscopic cholecystectomy and resulting in 11 conversions (11/44: 25%). The causes of the higher rate of conversion were the grave inflammation and slow dissection of central formation. There were no serious complication and mortality in both groups. It was diagnosed bile leak (two cases) which ceased spontaneously, one haematoma in abdominal layers, and one trocar's hernia. The authors have recommended the laparoscopic cholecystectomy for early diagnose acute cholecystitis in order to prevent the complications and reduce the sick-leave. Supporting their viewpoint the most important clinical end economical facts are: the recurrence of inflammation forced urgent surgery and caused more complication in the course of "a froid" phase there were scrutable anatomical situation the patients recovered in a shorter time.

Acute Disease↗

PubMed1999

The laparoscopic technique for bilateral inguinal hernias.

From March 1994 to March 1999 359 laparoscopic hernioplasties have been performed on 295 patients. In 349 cases (97.2%) TAPP (transabdominal preperitoneal), in 10 cases (2.8%) TEP (total extraperitoneal) method was used for the treatment. In 64 cases (21.7%) bilateral hernias were operated using TAPP-method only. There were 15 hidden hernias and 14 recurrences on the contralateral side in this group. The hernial ring was covered with two smaller meshes or one bigger. There were no intraoperative complications. In 21 cases (32.8%) subcutaneous emphysema and in 3 cases (4.6%) sero-haematoma was developed. The emphysemas were solved spontaneously in 2-3 hours after the surgery. One haematoma was needed punction. The patients were discharged from the hospital on the second or third postoperative day. The authors found that the bilateral laparoscopic hernioplasty much more favourable for the patients.

Adolescent↗

PubMed1999

Synchronically performed laparoscopic cholecystectomy and hernioplasty.

Cholecystectomies and hernioplasties are the two most frequently performed surgical interventions. The laparoscopic technique can be offered for the simultaneous treatment with both operating indications. The synchronical operation can give all the advantages of the minimally invasive technique. Authors had performed laparoscopic cholecystectomy with laparoscopic hernioplasty in five cases. Two inguinal and three postoperative hernias were reconstructed. The cholecystectomy was performed with a "three punction method", and the hernioplasty by using the same approach, completed by inserting a fourth assisting trocar as required. The hernial ring was covered with an intraperitoneally placed mesh, which was fixed by staplers (the so-called "IPOM-method": intraperitoneal on-lay mesh). There was no intra-, nor postoperative complication. The hernioplasty combined with laparoscopic cholecystectomy did not have effect on postoperative pain and nursing time. The return to the normal physical activity was short, similar to laparoscopic hernioplasty (in 1-2 weeks). Authors conclude that the simultaneous, synchronous laparoscopic cholecystectomy and hernioplasty is recommended and should be the method of choice because it is more advantageous for patients.

Adult↗

PubMed1998

Differential stimulation of c-fos expression in hypothalamic nuclei of the rat brain during short-term heat acclimation and mild dehydration.

Activation of central nervous structures involved in the perception and integration of thermo- and osmoregulatory signals was investigated in the Sabra rat. Male rats were either non-treated (C-E), water-deprived for 24 h (C-D), short-term acclimated to 34 degrees C for two days (STHA-E) or subjected to both stimuli (STHA-D). Immunoreactivity for c-Fos protein (Fos-IR) as marker for neuronal activation was quantified in (extra-)hypothalamic structures: organum vasculosum laminae terminalis (OVLT); subfornical organ (SFO); medial (MPA), ventromedial preoptic (VMPO) and lateral hypothalamic (LHA) areas; median preoptic (MnPO), magnocellular supraoptic (SON) and paraventricular (mPVN) nuclei; limbic lateral septal (LS) and thalamic paraventricular (PV) nuclei. Compared to C-E rats, dehydration markedly increased Fos-IR exclusively in neurons of the OVLT, SFO and MnPO known to be involved in osmoreception, in the mPVN and SON, and to a minor extent in the VMPO. The VMPO, MPA, LHA and LS-important (extra-)hypothalamic sites for the perception and integration within the thermoregulatory control circuit-exhibited intense elevation of Fos-IR upon short-term heat acclimation. Of all (extra-)hypothalamic structures involved in central osmoregulation, only the MnPO revealed heat-induced Fos-IR in numerous cells located preferentially in its rostral component. Thus, the MnPO proved to be activated during both thermal and osmotic stimulations applied separately. Subjected to the combined stress (STHA-D), most brain structures investigated showed striking Fos-IR due to thermally enhanced osmotic stimulation, with additive effects demonstrated in the MnPO. The data support differential central activation of c-fos expression due to thermal or osmotic stimulations, with the MnPO acting as putative integrative center for both autonomic control circuits.

Acclimatization↗

PubMed1998

Nitric oxide as a peripheral and central mediator in temperature regulation.

In animals including humans nitric oxide (NO) serves as a biological messenger both peripherally at neuroeffector junctions and in the central nervous system where it modulates neuronal activity. Evidence for the involvement of NO in homeostatic control is accumulating also for temperature regulation in homeotherms. In the periphery an auxiliary role in the vasomotor control of convective heat transfer to heat dissipating surfaces and modulation of thermoregulatory heat generation, especially in brown adipose tissue as the site of nonshivering thermogenesis, are discussed as NO actions. At the central level a thermolytic role of NO in thermoregulation as well as in fever is assumed, however, experimental data opposing this view suggest that topical specificity may be important. At the level of single neurons, the observed interrelationships between thermosensitivity and responsiveness to NO are still not consistent enough to reconcile these data with the effects of NO-donors and inhibitors of NO-synthase on temperature regulation.

Animals↗