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Biomedical subjects

E Simon

Publications and source records attributed to E Simon.

At least 37 records · Page 2Linked to original sources
PubMed2002

Modified electrodes for NADH oxidation and dehydrogenase-based biosensors.

The direct electrochemical oxidation of beta-nicotinamide adenine dinucleotide (NADH) at clean electrodes proceeds through a radical cation intermediate at high overpotentials and is subject to rapid fouling. Consequently, there has been a considerable body of work over the last 20 years looking at ways in which to catalyse the reaction using a wide variety of different types of modified electrode. These studies have resulted in a good knowledge of the essential features required for efficient catalysis. In designing modified electrodes for NADH oxidation, it is not only important to identify suitable redox groups, which can catalyse NADH oxidation and can be attached to the electrode surface; it is also important to ensure facile charge transport between the immobilised redox sites in order to ensure that, in multilayer systems, the whole of the redox film contributes to the catalytic oxidation. One way to achieve this is by the use of electronically conducting polymers such as poly(aniline).

Biosensing Techniques↗
PubMed2002

[Morphologic disequilibrium of the lips].

The aetiologies of the labial desequilibrium are multiple. They respond to the anomalies of the position and the dimension. The authors will enumerate the different variety and their etiology.

Adult↗
PubMed2002

[Red lip defects. Reconstructive techniques and indications].

The attractive color of the red lip must be the object of very meticulous reconstruction in their form and pigmentation. This can be done only by using the buccal mucosa. The graf is less indicated. There are multiple local flaps that have been proposed using the same lip, the jugal mucosa and the tongue. The authors will show the principal procedures found in the literature.

Humans↗
PubMed2002

[Labial aging. Composition and therapeutic principles].

Labial ageing process combining relaxation, distension and ptosis is aggravated by underlying structure modification: dental and bony. If the inferior lip moves back and collapses, the superior lip will go down and widen. The authors analyse the different ageing process components (intrinsic and extrinsic) as well as therapeutic principles.

Adolescent↗
PubMed2002

[Full thickness defects of the lips. Reconstructive techniques and indications].

The full-thickness tissue loss of the lip leads to the loss of lip continuity. The classic principle is to repair a lip with a lip, giving the best results. Although the size of tissue lost can force to use local flaps, these could be naso-labio-jugal, labio-mental or submental. Even though the microsurgical labial replantation is the technique of choice, unfortunately, most of the time it cannot be done as a result of the situation and the conservation of the avulsed fragment.

Humans↗
PubMed2002

[Labial commissures. Reconstructive procedures and indications].

The commisures are the two extremities of the mouth. They make a big complex in their architecture and their function. Their repairing should have an important attention to their final shape and function. The frequency of the retraction of the scarring tissue imposes additional muscular exercise which has to be premature, intense, and prolonged.

Humans↗
PubMed2002

[Labial balance].

The labial balance appreciated by statics and movement is the guarantee of morphology, bilabial competence and symmetry in function (ou bien in movement?). The restoration of the lips aims for this balance, the basic axiom is "to repair the lip by the lip". Three main technical forms meet these requirements: forward movement, rotation and transposition.

Biomechanical Phenomena↗
PubMed2001

Post-extraction complications seen at a referral dental clinic in Dar Es Salaam, Tanzania.

AIM: To investigate the types and magnitude of post extraction complications. SETTING: A referral hospital in Dar es Salaam, Tanzania. SUBJECTS: All dental patients who had their teeth extracted at the Muhimbili Medical Centre dental outpatient clinic during the study period (May September 1999). A total of 3,818 extractions were performed under local anaesthetic in 3,732 patients. METHOD: Oral examination of all patients who reported back with post-extraction problems. RESULTS: The frequency of post extraction complications was low (1.1 per cent), and was mainly due to; infected sockets (48.7 per cent), followed by bleeding sockets (41.0 per cent) and retained roots (10.3 per cent). There were eight 'other' complications suffered by 11 patients: necrotising fasciitis (n=l), herpes zoster (n=l), Ludwig's angina (n=l), infections of the submandibular (n=l), parapharyngeal (n=2), masticator (n=2) and submasseteric spaces (n =2), and reaction to local anaesthesia (2ml of 2 per cent lignocaine hydrochloride) (n=1). CONCLUSION: The results of this study indicate that post-extraction complications are few, mostly minor, self-limiting and easily treatable. The study does not support routine antibiotic prophylaxis or special pre-extraction procedures, even in this patient population with poor oral hygiene and high HIV seroprevalence.

Abscess↗
PubMed2001

Erythrocyte, but not plasma, vitamin E concentration is associated with carotid intima-media thickening in asymptomatic men at risk for cardiovascular disease.

Epidemiological data regarding the preventive role of vitamin E in the pathogenesis of atherosclerosis have yielded conflicting results, possibly because endpoints considered were clinical events but not detection of atherosclerosis per se. Otherwise, it has been suggested that the measure of the erythrocyte alpha-tocopherol level may be more suitable to assess the human tocopherol status than its plasma level. We investigated the association between early atherosclerosis in superficial arteries assessed noninvasively and the alpha-tocopherol status in 261 asymptomatic men at risk for cardiovascular disease. alpha-Tocopherol concentrations in plasma, HDL, and erythrocytes were determined using a reverse-phase HPLC method. Detection of carotid plaques and measure of carotid intima-media thickness (IMT) were performed using high-resolution B-mode ultrasonography. The main result of this study is the observation of a negative correlation (P<0.01) between carotid IMT and erythrocyte alpha-tocopherol concentration, independently of conventional cardiovascular risk factors, whereas no such association has been found with plasma (total or HDL) alpha-tocopherol concentrations. No association has been evidenced between alpha-tocopherol concentrations and carotid plaques. These results emphasize the primary protective role of vitamin E in the early phases of atherosclerosis and the significance of the erythrocyte alpha-tocopherol concentration as a marker of atherosclerosis.

Arteriosclerosis↗
PubMed2001

The effect of leptin treatment on the development of obesity in overfed suckling Wistar rats.

OBJECTIVE: To identify the role of hyperleptinaemia in mediating the effects of early postnatal overfeeding in a rat strain known to be prone to manipulations of the early environment which result in predispositions for obesity and associated metabolic and cardiovascular disturbance in later life. DESIGN: Wistar rats were reared in normal litters (NL, 10--12 pups) or small litters (SL, four pups) from postnatal day 3 and killed for determination of body composition and plasma leptin and insulin concentrations on day 7 or day 21 after having been treated with recombinant leptin (2 x 50 (pmol/g)/day) or saline from day 1. RESULTS: Rearing in SL doubled the body fat content and plasma leptin levels in comparison to NL pups by 21 days of age. Under leptin-treatment throughout suckling age, NL pups remained leptin responsive, ie the difference in body fat content was progressively reduced relative to the controls. Until 7 days of age, despite the body fat content of untreated SL pups being 2-fold higher and their plasma leptin level 7-fold higher than that of NL pups, leptin treatment caused the same percentage decreases in body fat in SL than in NL pups. But in contrast to NL pups, the SL pups became leptin resistant thereafter. Plasma insulin levels in 7-day-old leptin-treated SL pups were 3-fold higher than in untreated littermates and 5-fold higher than in the NL groups. CONCLUSION: Prophylactic leptin treatment does not prevent hyperinsulinaemia and excessive fat deposition in SL pups. On the other hand, selective hyperleptinaemia during suckling age does not trigger leptin resistance and obesity in NL pups. Rather than hyperleptinaemia per se, other factors associated with early postnatal overnutrition, for example, the concurrent hyperinsulinaemia, seem to play a pivotal role for the development of leptin-resistance and life-long obesity risk in SL rats.

Animals↗
PubMed2001

Amylin potently activates AP neurons possibly via formation of the excitatory second messenger cGMP.

Amylin is secreted with insulin from the pancreas during and after food intake. One of the most potent actions of amylin in vivo is its anorectic effect, which is directly mediated by the area postrema (AP), a circumventricular organ lacking a functional blood-brain barrier. As we recently demonstrated, amylin also stimulates water intake most likely via its excitatory action on subfornical organ (SFO) neurons. Neurons investigated under equal conditions in an in vitro slice preparation of the rat AP were 15-fold more sensitive to amylin than SFO neurons. Amylin (10(-11)-10(-8) M) excited 48% of 94 AP neurons tested; the remaining cells were insensitive. The average threshold concentration of the excitatory response was 10(-10) M and, thus, close to physiological plasma concentrations. Coapplication of the amylin receptor antagonist AC-187 reduced amylin's excitatory effect. Amylin-mediated activation of AP neurons and antagonistic action of AC-187 were confirmed in vivo by c-fos studies. Peripherally applied amylin stimulated cGMP formation in AP and SFO neurons, as shown in immunohistochemical studies. This response was independent of nitric oxide (NO) formation in the AP, while coapplication of the NO synthase inhibitors N-monomethyl-L-arginine (100 mg/kg) and nitro-L-arginine methyl ester (50 mg/kg) blocked cGMP formation in the SFO. In contrast to the SFO, where NO-dependent cGMP formation seems to represent a general inhibitory transduction pathway, cGMP acts as an excitatory second messenger in the AP, since the membrane-permeable analog 8-bromo-cGMP stimulated 65% of all neurons tested (n = 17), including seven of nine amylin-sensitive neurons (77%). The results indicate that the anorectic effect of circulating amylin is based on its excitatory action on AP neurons, with cGMP acting as a second messenger.

1-Methyl-3-isobutylxanthine↗
PubMed2001

[Orthopedic treatment of labio-maxillo-palatal clefts: our approach].

Many authors use a preliminary orthopedic procedure before cleft lip and palate surgical closure in order to prevent possible bone distortion following the rupture of the muscle belts resulting from the cleft. Actually, this is generally not only an orthopedic treatment but rather a surgical orthopedic step which includes lip adhesion before the surgical closure of the clefts. Following the procedures proposed by Georgiade and Latham, we have used since 1996 a treatment based on traction applied with an elastic chain on splints attached by transmaxillary pins for certain types of clefts, namely unilateral complete clefts with endognathy of the small fragment, unilateral complete clefts larger than 7 mm, bilateral wide complete clefts with premaxilla protrusion, and bilateral wide complete clefts with collapsus and premaxillary protrusion. Technical procedures vary with the type of cleft. Standard procedures with or without jacks are used for the other types of complete clefts. These orthopedic procedures with elastic traction are performed between the 3rd and 6th week, before lip adhesion of the upper part of the lip (combined with release of skin and subcutaneous tissues from the underlying alar cartilage). A palatine plate with or without a jack, fitted most of the time with a spring for nostril support, is then inserted until surgical closure.

Bone Nails↗
PubMed2000

Interaction of genetic and environmental programming of the leptin system and of obesity disposition.

Possible adverse interactions between an usually inconspicuous genetic trait and early environmental factors favoring the development of obesity were investigated in rats heterozygous for the leptin receptor defect "fatty" (fa). Pups were exposed to early postnatal overfeeding by reducing litter size from normally 10-12 to only 4. Rearing +/+ and +/fa pups from day 3 to 21 in small litters increased fat-free dry mass and body fat, but only in the latter did a significant interaction with genotype occur. Pronounced differences in the responsiveness of +/+ and +/fa pups to "prophylactic" leptin treatment (from day 1 to 21) were observed, with +/fa females from small litters being nearly as fat and unresponsive as previously reported for normally reared fa/fa pups. Clear heterozygous differences in total hypothalamic leptin binding, but no litter size effect, paralleling the differences in leptin responsiveness, were observed. By early postnatal overfeeding an usually inconspicuous genetic trait may thus become etiologic for the development of obesity via physiological changes other than the decreased leptin binding characterizing the genetic defect.

Adipose Tissue↗
PubMed2000

Study of vitamin E net mass transfer between alpha-tocopherol-enriched HDL and erythrocytes: application to asymptomatic hypercholesterolemic men.

We previously showed that hypercholesterolemic asymptomatic men had lower erythrocyte vitamin E content, despite normal plasma concentrations compared to normocholesterolemic men. We hypothesized that the reduced erythrocyte vitamin E concentration could be due to an impairment of transfer of vitamin E from plasma lipoproteins. We first developed a model for testing the ability of erythrocytes to accept vitamin E from high-density lipoproteins (HDL) pre-enriched in vitamin E, which allows to measure a net mass transfer of vitamin E from HDL to erythrocytes. Vitamin E-enriched HDL were obtained in controlled conditions of concentration and incubation time with a good reproducibility (CV </= 10%). The kinetic study of the net mass transfer of vitamin E to erythrocytes of healthy volunteers shows small inter- and intraindividual variations. The application of this model to erythrocytes of hyper- and normocholesterolemic men demonstrates that the reduced erythrocyte vitamin E content observed in hypercholesterolemic men was not due to a reduced ability of these cells to accept vitamin E from HDL. It might rather be due to an impairment of lipoproteins in the delivery of vitamin E to tissues, or to an oxidative stress which consumes antioxidants.

Biological Transport, Active↗
PubMed2000

Utilisation of dental services in Tanzania before and after the introduction of cost-sharing.

OBJECTIVE: The objective of this study was to evaluate the effect of cost-sharing, introduced in July 1994, on the utilisation of dental services in Tanzania. METHODS: The study compared dental attendance, demand for dental services and treatment pattern of patients in 17 out of 20 regions of mainland Tanzania in 1993 and 1995, a year before and after the introduction of user fees. OUTCOMES MEASURES: Dental attendance and demand for treatment. RESULTS: Results revealed a 33.2 per cent overall reduction in dental attendance but no effect on either the demand for treatment or treatment pattern. The exceptions were increases in referral cases by 14.5 times and prosthetic work by 3.9 times, and a reduction in surgical cases by 18.8 per cent. CONCLUSIONS: In order to improve attendance and decrease referrals it is necessary to enforce the first line of oral primary health care to meet the simple treatment demands. Furthermore, the revenue generated by cost-sharing should be used to improve services.

Adolescent↗
PubMed2000

Orexin A activates leptin-responsive neurons in the arcuate nucleus.

Orexins, also named hypocretins, are newly described neuropeptides, which are produced almost exclusively in neurons of the lateral hypothalamus and have been shown to increase food intake after intracerebroventricular injection. Leptin, the ob-gene product released from white adipocytes, is suspected to reduce food intake mainly by acting on neurons in the arcuate nucleus of the hypothalamus. Application of orexin A activated 85% (66 out of 78) of all neurons of the rat arcuate nucleus investigated electrophysiologically in an in vitro slice preparation, by a direct excitatory postsynaptic effect. Leptin inhibited electrical activity in 10 out of 22 orexin-sensitive neurons in this brain region and excited only 3 neurons. These data give the first indication as to where and how orexin might interact with the leptin-responsive hypothalamic network.

Animals↗
PubMed2000

The enigma of deep-body thermosensory specificity.

Information provided by the analysis of peripheral cold and warm receptors may be considered a useful guide for assessing the specificity of thermal information originating in deep-body tissues. A wealth of data concerning the location of deep-body thermosensors and their neuronal correlates and modes of transduction permits the following theses to be proposed. 1. Unlike the peripheral warm and cold receptors, deep-body thermosensors are only in part represented by afferent fibers, mostly warm sensitive ones that are not characterized in detail, as the source of thermal information outside the central nervous system (CNS). The more important thermal information generated in the CNS originates mainly from warm-sensitive neurons but contributions of cold-sensitive neurons are not definitely excluded. 2. Unlike the peripheral thermoreceptors, monomodality with respect to natural physical stimuli does not seem to be an essential property of deep-body thermosensors. By contrast, multimodality may underlie at least some of the multitude of interactions between thermoregulatory and other homeostatic control systems. 3. Temperature transduction seems to utilize molecular mechanisms that are also found in neurons that lack any thermosensory functions, and so the transduction mechanisms identified in warm-sensitive CNS neurons do not seem to be specific per se. 4. The observation of a multitude of temperature/response characteristics for thermosensitive CNS neurons has been helpful for categorizing these neurons, but there is no clear information that any one might be particularly relevant. 5. Originating from the peripheral cold and warm receptors two separate but interacting cold- and warm-signal pathways ascend multisynaptically to the hypothalamus as the highest level of thermoregulatory control, and to some extent go further to the sensory cortex. The signal contributed by a deep-body thermosensitive neuron, irrespective of its location, attains specificity by being fed properly into one of the two ascending thermosensory pathways.

Body Temperature↗