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Biomedical subjects

A Rougier

Publications and source records attributed to A Rougier.

At least 73 records · Page 4Linked to original sources
PubMed1990

The epileptic focus versus the pathological focus.

The relationship between the epileptic focus and the causative lesion has been studied to define when resection of the epileptic focus may be associated with removal of the lesion. Experimental studies reveal that a maturation phase is followed by a progressive autonomisation of the epileptic focus from the induced lesion. Thereafter there may be a progressive course to such experimental epilepsy with spreading of the epileptic lesions and possible creation of a secondary focus. However, in man the findings are less coherent and sometimes contradictory. In long term intractable epilepsy, simple removal of the causative lesion can be effective. A hypothesis is proposed to explain these phenomena--the hypothesis of systemic focal epileptogenesis. It is further proposed that endogenous excitotoxic agents such an quinolinic acid may have effects on the epileptic focus only when the causative lesion is present producing a subtle modification of the blood brain barrier.

Brain Diseases↗
PubMed1990

In vivo percutaneous absorption: a key role for stratum corneum/vehicle partitioning.

Percutaneous absorption of five compounds was studied in the hairless rat in vivo: benzoic acid, caffeine, hydrocortisone, inulin and thiourea. The results clearly demonstrate that, as with in vitro experiments, a steady-state flux can be achieved in vivo. This steady-state flux is strongly molecule dependent. Thus, the values for inulin and benzoic acid differ by a factor of about 40. In contrast, although the physicochemical properties of the studied compounds vary widely, their lag times were not significantly different. The mean lag time was 11 +/- 2 min. Different compounds could be considered to have approximately the same apparent diffusion coefficient with regard to their percutaneous absorption in vivo. Thus, for a given thickness of stratum corneum and a given anatomical site, the penetration flux value of a substance depends only on its stratum corneum/vehicle partition coefficient. Using a classical model, we have demonstrated that the amount of substance present in the stratum corneum (Qsc) at equilibrium (30 min) is related to this partition coefficient. There is also a linear relationship between steady-state flux and Qsc. In practice, the in vivo steady-state flux of penetration of a compound can be predicted from the simple measurement of the amount present in the stratum corneum after a contact time of 30 min.

Animals↗
PubMed1990

New fatty monoesters of erythromycin A.

New fatty polyenic (linoleic, linolenic, arachidonic, linoelaidic) mono esters of erythromycin A have been synthesized by using various reagents such as acyl chloride, carboxylic acid anhydride, and mixed carbonic anhydride. These different ways of activating the fatty acid allowed a regioselectivity of esterification at position 2' of the desosamine ring or position 4" of the cladinose ring of erythromycin A. The in vitro antibacterial properties of these new esters against members of the resident flora of the human skin were determined and compared with those of erythromycin A. The number and the stereochemistry of the double bonds seem to play a crucial role in the expression of the in vitro antibacterial activity.

Bacteria↗
PubMed1989

[Radiotherapy and cerebral stereotaxis. Examples of dosimetry with 3D reconstruction].

External stereotactic radiotherapy allows to irradiate a small and carefully delimited intracranial volume according to the spatial definition of the target. To determine the distribution of the dose in the volume irradiated, we developed a dosimetric programme adapted to our particular treatment conditions (arc therapy in the frontal and oblique planes converging onto the centre of the target volume with circular beams 8 to 20 mm in diameter using 18 MV X photons). The principle of the programme is a 3D reconstruction based on ten transverse CT slices. This reconstruction, related to the stereotactic coordinates defined during stereotactic localization, visualises the outline of each oblique frontal treatment plane and the outline of the three perpendicular reference planes passing through the centre of the target volume (i.e. transverse, sagittal, coronal). The isodose distribution is then calculated in the planes defined by these reconstructions. Under treatment conditions, we use the parameters measured for each beam with their additional collimation. We present an evaluation of this software performed on a phantom consisting of a skull containing a defined target.

Humans↗
PubMed1988

[MRI and surgery of epilepsy].

The evaluation of M.R.I. in the presurgical management of epilepsies requires establishing the significance of the abnormal signals. In 15 cases, correlations among M.R.I., electrophysiological data obtained by chronic intracerebral recordings and histological examination were studied. Abnormalities were detected by M.R.I. in 12 cases (80%). An accurate epileptic-focus topographical orientation was obtained by M.R.I. in 10 cases. But M.R.I. findings did not coincide with functional data obtained by S.E.E.G. recordings. Abnormalities detected by M.R.I. led to rectify the previous hypothesis about the epileptic focus localization in two cases. One false positive and one case of incomplete data would have been misleading if S.E.E.G. had not been performed. M.R.I. abnormalities included two morphological changes and ten high intensity T2 signals. The increased T2 intensity was more often focal (9) than diffuse (1). Among the 8 cases of increased T2 intensity correlated to the epileptic focus, 1 was histologically normal, 3 corresponded to specific lesions (astrocytoma: 1, hamartoma: 2) and 4 corresponded to non specific lesions (gliosis: 2, spongiosis: 2). When M.R.I. was normal at the site of the epileptic focus, either no alteration (2) or non specific lesions (2) were found. Uncus herniation could not be identified with M.R.I. M.R.I. has proven sensitive, detecting small epileptogenic lesions missed by C.T. Moreover in some cases, high T2 signals have been correlated topographically with the epileptic focus and histologically with non specific lesions. These signals are more likely related to a functional phenomenon such as an increase in water content than to the histopathological findings themselves.

Adolescent↗
PubMed1987

In vivo percutaneous penetration of some organic compounds related to anatomic site in humans: predictive assessment by the stripping method.

The effect of anatomic site on the in vivo relationship between the total penetration of four compounds and the amount of the compounds present in the stratum corneum at the end of application was studied in humans. For each anatomic site, 1,000 nmol of 14C-radiolabeled benzoic acid, benzoic acid sodium salt, caffeine, or acetylsalicylic acid was applied to 1-cm2 area of skin of male Caucasian patients aged 28 +/- 2 years (groups of 6-8). For each molecule and each site, a first application on the right-hand side of the body allowed total absorption to be determined by measuring the amount excreted in the urine. A second application, performed 48 h later on the contralateral site, enabled the total amount of substance present in the stratum corneum at the end of application (30 min) to be assessed after cellophane-tape stripping of the treated area. The results showed that skin permeability varied substantially, depending both on the physicochemical nature of the molecule and on the anatomical location. In general, the rank order in skin permeability of the studied areas appears to be as follows: arm less than or equal to abdomen less than postauricular less than forehead. Whatever the compound applied, the forehead was approximately 2 times as permeable as the arm or abdomen. Independent of the origin of the differences in permeability observed among sites, there exists a linear correlation (r = 0.97, p less than 0.001) between the amounts of substance present in the stratum corneum at the end of application (30 min) and the total amounts which penetrated within a 4-d period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

In vivo relationship between transepidermal water loss and percutaneous penetration of some organic compounds in man: effect of anatomic site.

The relationship between the percutaneous penetration of four chemicals and transepidermal water loss (TEWL) was investigated in vivo in man as a function of anatomic site. The findings showed an appreciable difference in the permeability of the skin from one site to another with regard to both water loss and chemical penetration. In addition, independent of the physicochemical properties of the molecules administered, there was a linear relationship between TEWL and penetration. These data confirm both the importance of anatomic site in the degree of permeability of the cutaneous barrier and the utility of determinations of TEWL and percutaneous absorption in the evaluation of its functional condition.

Absorption↗
PubMed1987

The hairless rat: a relevant animal model to predict in vivo percutaneous absorption in humans?

Percutaneous absorption of 4 radiolabeled molecules was compared in the hairless rat (back) and in different anatomic sites in human (arm, abdomen, postauricular, forehead). The conditions under which these 4 compounds were administered (area treated, dose, vehicle, contact time, etc.) were similar in both species. The results showed that, in humans and rats, there exists the same rank order in total absorption: benzoic acid sodium salt less than caffeine less than benzoic acid less than acetylsalicylic acid. In both species there was a factor of 3 between the most and the least absorbed molecule. Although skin permeability varied significantly with the physicochemical nature of the compound administered, it also depended on the anatomic site involved. Independent of the molecule studied, the rank order of permeability of the sites tested in humans appeared as follows: arm less than or equal to abdomen less than postauricular less than forehead. There was a factor of 3 between the most and the least permeable sites. For each molecule and each anatomic site, the ratios of total percutaneous absorption human/hairless rat (back) were determined. For a given anatomic site and whatever the molecule tested, these ratios were constant. It thus appears that when conditions are carefully controlled, it may be possible, by measurements on animals, to predict the absorption of a compound in humans. Further experimentation with chemicals of varied physicochemical properties will be required for validation of the model.

Absorption↗
PubMed1987

[Relation between inter-critical and critical stereoelectroencephalographic elements: consequences on the results of cortectomies].

Surgical results in 31 cases of cortectomy for epilepsy are reported with stereoelectroencephalographic recordings. The relationships between the cortical area characterized by inter-ictal spikes (irritative area) and the site of the ictal discharge (epileptogenic focus) lead to define two situations: the two areas were considered similar in 11/21 temporal lobe epilepsy and 3/10 frontal lobe epilepsy. Surgical results were then excellent; when the irritative area was not totally included in the cortectomy, surgical results were less good. This situation was more frequent in frontal lobe (70 p. 100) than in temporal lobe epilepsy (47.5 p. 100). However in 7/17 of theses cases, the seizures disappeared or decreased by 90 p. 100. Therefore the irritative area can be considered hetereogeneous. Ictal and interictal stereo-EEG data contain non-redundant information. The inter-ictal EEG patterns contributing to the definition of the epileptogenic area are discussed.

Adolescent↗
PubMed1986

Regional variation in percutaneous absorption in man: measurement by the stripping method.

The influence of anatomic site on the relationship between total penetration of a molecule and its quantities present in the stratum corneum (SC) 30 min after application was quantified in an in vivo study. For each site, six male volunteers received two symmetrical applications of 1,000 nmol benzoic acid 14C to an area of 1 cm2 for 30 min. The first application permitted measurement of total absorption of benzoic acid within 4 days (urinary excretion method), while the second enabled determination of the quantity of benzoic acid in the SC at the end of the application time. Total penetration according to site is: back less than arm less than chest less than thigh less than abdomen less than forehead, (with the forehead being three times more permeable than the back). Whatever the sites and the origin of the differences observed, the results show that the single measurement of the amounts of a compound present in the SC at 30 min postapplication appears sufficient to predict its total penetration, these two parameters being linearly correlated (r = 0.97, P less than 0.001).

Adult↗
PubMed1986

[Contribution of the stereo-EEG to the definition of an epileptic focus].

For epilepsy, surgical success rates rely on the validity of the spatial definition of the epileptogenic focus. Clinical seizure characteristics and interictal and ictal EEG patterns have been the traditional means of localization. Electrocorticography and stereo-electroencephalography are sometimes used. With stereo-EEG, the topographic determination of an epileptogenic zone depends above all on the study of the anatomo-electro-clinical correlations evidenced during the seizures themselves. Interictal abnormalities, infra-clinical discharges, stimulations also help to evaluate the topography of the focus. Because surgical success is increased neither with stereo-EEG nor with EEG, the procedure remains controversial. But stereo-EEG allows the selection of 36% more patients for surgery by defining otherwise unidentifiable single epileptogenic foci (Spencer). Furthermore, the use of stereo-EEG in seizure disorders of extra-temporal origin is a real diagnostic benefit.

Electroencephalography↗
PubMed1986

The measurement of the stratum corneum reservoir: a simple method to predict the influence of vehicles on in vivo percutaneous absorption.

The influence of nine vehicles on in vivo percutaneous absorption of benzoic acid has been studied in the hairless rat. Although the vehicles used were simple in composition, the total amount of benzoic acid which penetrated varied by a factor of 50. A weak relationship was found between penetration of benzoic acid and its maximum solubility in the different vehicles. A linear relationship was demonstrated between the amount of benzoic acid present in the stratum corneum at the end of a 30 min application period and the total amount absorbed over 4 days. We suggest that the influence of a vehicle on the overall absorption of a substance can therefore be predicted by simply measuring the amount present in the stratum corneum at the end of a 30 min application period.

Animals↗
PubMed1986

[Amino acids in human epileptogenic foci].

The functional status of GABA synapses together with tissue levels of other putative neurotransmitter amino acids was studied in epileptogenic foci (identified by stereo-EEG) removed neurosurgically from 14 epileptic patients unresponsive to anti-epileptic medication. L. glutamic acid decarboxylase was lower than normal in epileptogenic cortical tissue from 10 to 12 patients. 3H-GABA-"A" receptor binding was low in all epileptogenic tissue examined. GABA levels were unchanged, whereas glutamate was increased in 7 patients. These studies confirm previous observations that there is a decreased functional activity of GABA synapses in a high proportion of epileptogenic foci. Therefore these data indicate that there is indeed an imbalance between excitatory and inhibitory neurotransmitter systems.

Amino Acids↗