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Biomedical subjects

C Morel

Publications and source records attributed to C Morel.

At least 73 records · Page 4Linked to original sources
PubMed1997

The role of Linac radiosurgery in multidisciplinary management for cerebral arteriovenous malformations: personal experience.

The authors analyze their personal series of 90 patients with cerebral arteriovenous malformations (AVMs) concerning the place of radiosurgery (RS). Out of the 90 patients, 34 undervent Linac RS-RS was used as single treatment (17%) or in combination with embolization or surgery (21%.) Eradication rate assessed angiographically after 2 years was 89%. Regarding this personal series and the recent literature, several questions remain: should small superficial AVMs revealed by hemorrhage be irradiated or operated on and the role of embolization as a reductive method before RS in order to reduce the complications and improve the obliteration rates.

Cerebral Angiography↗
PubMed1997

Discrepancies between HMPAO and ECD SPECT imaging in brain tumors.

Among several brain radiopharmaceuticals for SPECT imaging, 99mTc complexes of HMPAO and ECD are the most widely used. They are considered to be equal in their capacity to reflect regional cerebral blood flow; but discrepancies between HMPAO and ECD brain uptake have been reported in stroke patients. This paper reports our observations regarding discrepancies between HMPAO and ECD SPECT in 14 of 23 patients with suspected brain tumors or presumed metabolic cerebral abnormalities. We obtained similar conflicting results, namely focal HMPAO hyperactivities and isoactive ECD SPECT. The majority of these discrepancies were found in patients with brain tumors (10 of 13 patients), while only 4 of the 10 remaining patients with nontumoral process showed similar discrepant results. The physiopathology behind these observations is discussed here, and it is likely to be related to the specific response to cellular metabolic disorders rather than to perfusion disturbances.

Adult↗
PubMed1997

[Postpartum cerebral angiopathy of iatrogenic origin].

A 30 year old women, beginning her 19th day postpartum, was admitted for lowering of alertness. The day before she complained of cephalalagia. Neurologic examination showed pyramidal tract signs on the right part of the body, a bilateral Babinski sign, and central oculomotor palsy. She started a treatment by nasal pulverization of phenylephrine, a sympathomimetic vasoconstrictor, one week before, and took bromocriptine (5 mg per day) from childbirth to second week postpartum. CT scan was normal. Lumbar puncture showed a high level of proteins, from transsudative origin. Cerebral angiography showed a beading aspect of arterial branches, especially in the left middle cerebral artery territory. Two days after drug withdrawal, the patient recovered. This angiographic pattern has already been described in cases of cerebral angiopathy due to sympathomimetic drug abuse, and in cases of postpartum cerebral angiopathy. The chronology, in our case, makes the responsibility of the phenylephrine very likely. Nonetheless, ergot derivatives (i.e. ergonovine, bromocriptine) have also been accused of giving cerebral postpartum angiopathy. In our case, we think that bromocriptine may have triggered the cerebral angiopathy due to phenylephrine.

Bromocriptine↗
PubMed1996

Localization of a gene coding for the phospholipase A2-L subtype (PLA2L) to human chromosome 8q24-qter.

Phospholipases A2 (PLA2) form an extended class of enzymes that play an important role in signal transduction. Phospholipase A2-like (PLA2L) belongs to the secreted forms of phospholipases A2, but constitutes a new subgroup. We have assigned the gene for this enzyme to human chromosome 8q24-qter using fluorescence in situ hybridization and radiation hybrid mapping techniques.

Animals↗
PubMed1996

Molecular study of nosocomial nocardiosis outbreak involving heart transplant recipients.

Randomly amplified polymorphic DNA analysis and rRNA gene restriction patterns (ribotyping) were compared as methods of investigating a nosocomial outbreak of nocardiosis involving three heart transplant recipients. No clear distinctions between three clinically related isolates and four unrelated strains were obtained by ribotyping. On the contrary, randomly amplified polymorphic DNA analysis with two selected primers, primers 2650 and DKU49, showed one pattern for the three related isolates and four patterns for the unrelated strains.

Adult↗
PubMed1996

[Positive corneal findings of Propioni bacterium acnes and keratitis].

PURPOSE: Propioni bacterium Acnes may be isolated from corneal specimens. Its presence usually evokes a neighbouring tissue contamination. Nevertheless we have tried to find arguments in favour of a possible pathological responsibility of this microorganism in corneal affections. MATERIAL AND METHODS: A retrospective study was conducted in thirty patients with proved P. acnes corneal infection. The specimens were collected immediately during the first examination in the emergency ward. The research of anaerobic bacteria was made for each corneal specimen. RESULTS: We studied nineteen corneal abscesses and eleven corneal ulcers. Ninety-one percent of the cases presented an associated irritating factor. In decreasing order we found: wearing of soft contact lenses (36%), foreign corneal body still in situ or recently removed (21%), recurrent corneal erosions (9%), palpebral surgery (6%), herpetic keratitis (6%) or rosacea (3%). P. acnes was the only microorganism identified in 97% of the cases. Starting treatment before bacteriological results were known to be effective in each case. CONCLUSIONS: These elements are an argument for the pathological role of P. acnes in corneal infections when combined with favourable local conditions. Its presence does not always mean actual contamination.

Abscess↗
PubMed1996

[Responsibility of incomplete retinal photocoagulation in the indication of vitrectomy in proliferative diabetic retinopathy].

PURPOSE: We report an epidemiologic study about prophylactic photocoagulation of ischaemic diabetic retinopathy in order to avoid proliferative stage and severe vitreous haemorraghe. METHODS: We studied retrospectively 42 eyes of 32 diabetic patients who underwent a vitrectomy in 1993. For each patient several items were analyzed: nationality, sex, age, type, duration and clinical course of diabetes, and other risk factors. Slit lamp and ocular fundus examination were noted; in particular lens, iris and vitreoretinal framework. RESULTS: Almost all patients had an inadequate laser photocoagulation: in 26 eyes (62%) it was insufficient or non-existent, uncomplete in 12 eyes (29%), and non confluent for 18 eyes (43%). Only four eyes have had complete and confluent panphotocoagulation. CONCLUSION: Photocoagulation appears to be the priority therapy to avoid most severe complications of proliferative diabetic retinopathy. Laser photocoagulation must be started from preproliferative retinopathy, confluent on the useless ischaemic retinal areas, and dense elsewhere.

Adult↗
PubMed1995

A comparison of period amplitude and power spectral analysis of sleep EEG in normal adults and depressed outpatients.

Three experiments were carried out to evaluate the relationship between two techniques for quantifying electroencephalographic (EEG) data during sleep: period amplitude analysis (PAA) and power spectral analysis (PSA). In Experiment 1, canonical correlations and regression analyses were computed on PSA and PAA data from 40 undergraduate volunteers. The results yielded an average canonical correlation of 0.98. Further, multiple regression analyses demonstrated that the PSA variables accounted for approximately 66% of the variance in the PAA data, whereas PAA variables captured 88% of the variance in the PSA data. Epoch-to-epoch correlations were higher for PAA measures than for PSA data, perhaps indicating greater stability of PSA measures across epochs of sleep. In Experiment 2, PSA and PAA data were compared in 17 unmedicated outpatients with unipolar depression. Canonical correlations and regression analyses indicated that the overlap in variance between PSA and PAA did not exceed 50%, regardless of whether PSA or PAA variables were used as predictors. Epoch-to-epoch correlations between PAA measures were significantly higher than correlations among PSA variables, again suggesting greater stability of PAA data across epochs of sleep. The range of correlations for either data set was, however, substantially lower in the depressed than in the normal group. Experiment 3 evaluated the possibility that filter settings and artifact-rejection procedures had contributed to reduced overlap in PSA-PAA variance and reduced stability in depressed patients. An additional group of eight healthy volunteers served as subjects. Findings in Experiment 3 indicated that methodological differences between Experiments 1 and 2 did not account for the reduced correlations in the depressed group. It was concluded that PSA and PAA data should be comparable in normal subjects but are relatively independent in depressed patients. Epoch-to-epoch correlations were higher for PAA data than those found between PSA measures in both normal subjects and depressed patients, suggesting that PAA may be more stable across sleep epochs. Reduced stability may be a reflection of nonstationarity in the EEG of depressed patients.

Adolescent↗
PubMed1995

Islet-specific proteins interact with the insulin-response element of the glucagon gene.

Glucagon gene expression is negatively regulated by insulin at the transcriptional level. G3, a DNA control element located in the 5'-flanking sequence of the rat glucagon gene mediates the inhibition of transcription, which occurs in response to insulin. We show here that two islet-specific protein complexes C1A and C1B, bind to the A domain of G3, which is critical for the insulin response. These two complexes bind to overlapping sequences of the A domain and display very similar binding specificities. Point mutations in the A domain that affect binding of C1A and C1B result in both decreased G3 enhancer activity and insulin-mediated inhibitory effects with a close correlation between diminution of binding and function. One of the two complexes, C1A, is similar or identical to B1, a protein complexes interacting with the upstream promoter element of the glucagon gene, G1, implicated in the A cell-specific expression of the glucagon gene. Our data indicate that islet-specific proteins are involved in glucagon gene regulation by insulin.

Animals↗
PubMed1995

The upstream promoter element of the glucagon gene, G1, confers pancreatic alpha cell-specific expression.

The glucagon gene is expressed in the endocrine pancreas, the intestine, and the brain. In the endocrine pancreas, expression of the glucagon gene is restricted to the alpha cells of the islets of Langerhans. We previously showed that 168 base pairs of the promoter was critical for this restricted expression. To further characterize the mechanisms involved in alpha cell specificity, we analyzed the responsible DNA sequences by transient transfection studies into glucagon- and insulin-producing cell lines. We localized alpha cell-specific sequences between nt 100 and 52, a region that corresponds to the upstream promoter element G1. Four protein complexes, B1, B2, B3, and B6 interact with G1; B6 requires most of G1 to be formed. B1, B2, and B3, by contrast, bind on closely overlapping sequences, display similar methylation interference patterns, and appear to be related complexes. Point mutations of G1 indicate, however, that their binding specificities are different. All four complexes are islet-specific, and impairment of their binding results in decreased transcription. We conclude that G1 interacts with islet cell-specific proteins to restrict glucagon gene expression to the alpha cells.

Alkaline Phosphatase↗
PubMed1995

Homologous DNA sequences and cellular factors are implicated in the control of glucagon and insulin gene expression.

The glucagon gene is specifically expressed in the alpha cells of pancreatic islets. The promoter of the glucagon gene is responsible for this specificity. Within the promoter, the upstream promoter element G1 is critical to restrict expression to the alpha cells. We define here a composite DNA control element, G4, localized upstream of G1 between nucleotides -100 and -140 which functions as an islet-specific activator in both glucagon- and insulin-producing cells but not in nonislet cells. G4 contains at least three protein binding sites. The most proximal site, E2, is highly homologous to the E1, SMS-UE, and B elements of the rat insulin I, somastatin, and elastase I genes, respectively, and interacts with a pancreas-specific complex; the distal site, E3, represents an E box which is identical to the E boxes of the rat insulin I and II genes and binds to a complex similar or identical to IEF1 which has been implicated in the tissue-specific control of insulin gene expression. These two sites necessitate a third element, the intervening sequence, to activate transcription. We conclude that the first 140 bp of the glucagon gene promoter contains at least two DNA control elements responsible for pancreatic alpha-cell-specific expression: G4, an islet cell-specific element sharing common binding sites with the insulin gene, and G1, which restricts glucagon gene expression to the alpha cells. This double control of specificity might have relevance during islet cell differentiation.

Animals↗
PubMed1995

[Treatment of refractory glaucoma with Nd:YAG laser cyclophotocoagulation].

We treated 54 eyes of 51 patients with refractory glaucoma by using contact transscleral Neodymium: YAG laser cyclophotocoagulation; 32 burns (7 watts during 0.7 second) were applied to each eye by positionning the anterior edge of the probe at 0.5 to 1 mm from the limbus. The mean preoperative intraocular pressure (IOP) was 33.7 mmHg and the mean postoperative IOP was 25.6 mmHg with a follow-up of five months. There was a decrease of IOP in 72.3% of the cases. The postoperative IOP was controlled (IOP < 21 mmHg) in 41.3% of the treated eyes. Pain decreased in 6.7% of the cases that had no control of IOP and they could stop their medical treatment. During the follow-up period we observed neither early post operative hypertonia nor phtisis bulbi. Three eyes had scleral perforations. Laser treatment can be repeated if necessary in no controlled IOP cases. We had less complications with the laser treatment than with cyclocryoapplication. We described the advantages of the contact probe used.

Adult↗
PubMed1995

[Search for etiology in 110 cases of uveitis. Value of punctures of the aqueous humor and vitreous body].

PURPOSE: Evaluation of the frequency of each aetiology, comparison with recent and previous publications, focus on less classical pathologies, and interest of some complementary investigations. METHODS: Prospective study of one hundred and ten cases of uveitis, submitted to aetiological investigations, including, when feasible or necessary, an anterior chamber paracentesis and a vitreous paracentesis. RESULTS: An aetiology was identified in 65% of the cases. Toxoplasmosis still remained the most frequent diagnosis (one out of four), followed by viral infection (15%), especially herpes simplex (9%), a notion as yet not mentioned in large statistical surveys, including recent ones. Tuberculosis allergy and rhumatismal diseases (ankylosing spondylitis) represent the two other large groups (5% each). The rest is divided among the other classical causes. These results, particularly toxoplasmosis and viruses, are always based on biological criteria, on the Witmer-Desmonts ratio in aqueous humour, or even the same ratio in vitreous. CONCLUSION: This study confirms the predominant role of anterior chamber paracentesis, the only means of establishing a firm diagnosis for certain categories of uveitis (toxoplasmosis and viruses); it is difficult to conceive how such an investigation can be questioned, to the benefit of a purely biomicroscopic diagnosis, leading to blatant errors, as demonstrated by the results of anterior chamber paracentesis. This study also shows, due to this paracentesis, the increasing role of viruses in the aetiology of uveitis, emphasizing the risks taken when any uveitis is systematically submitted to corticotherapy.

Adolescent↗
PubMed1995

[Non-refractive complications of keratectomy with Excimer laser in 141 myopic eyes].

PURPOSE: The purpose of this study is to evaluate the safety of myopic photorefractive keratectomy and to study the frequency of complications, excepted refractive problems. METHODS: A consecutive series of 170 eyes has been studied in a prospective trial low-up of one year for 107 eyes and six months for 34 eyes. Twenty-nine eyes have been lost. RESULTS: The main complication after six months is the loss of the best spectacle-corrected visual acuity. It was due to a haze in seven eyes (loss of one line in five eyes and four lines in one eye) and to an excentric ablation in three eyes (one line in two eyes and two lines in one eye), results found for treatments of six diopters or more. The haze is a constant complication. A direct relationship between the haze's intensity and the treatment importance was found as was an inverse relationship between the patient's age and the haze's intensity. The excentric ablations have no influence on the final visual acuity when they concern less than one millimeter. The epithelial problems were always of less importance. CONCLUSION: Except in corrections greater than seven diopters, complications are uncommon after Excimer for myopia. Patient's information has to be rigorous.

Adult↗
PubMed1995

[Retinal vein occlusion and resistance to activated protein C].

BACKGROUND: A new abnormality in the coagulation system, the resistance to activated protein C, has appeared among the numerous hereditary modifications which predispose patients to deep-vein thrombosis. The molecular abnormality responsible for the resistance to activated protein C is due to a mutation of an amino acid in the 506 position (Arg-->Gln) at the level of the factor V, designated under the name of factor V Leiden. METHODS: The authors wished to search for this alteration of the haemostasis in 106 patients with retinal venous occlusion hospitalized in Centre Hospitalier National d'Ophthalmologie des Quinze-Vingts (Paris). RESULTS: In our study of 106 patients presenting a retinal venous occlusion, the resistance to activated protein C was the most frequent coagulation abnormality found (4.71%), when compared with the other deficits of the inhibitors of the clotting system: protein S (2.80%), antithrombin III (0.94%) et protein C (0%). CONCLUSION: The test of resistance to activated protein C should be recommanded in cases of retinal venous occlusion, particularly in the search for a cause of thrombosis in young patients or in recurrent thrombosis.

Adult↗
PubMed1994

Glucagon gene expression is negatively regulated by hepatocyte nuclear factor 3 beta.

Pancreatic expression of the glucagon gene depends on multiple transcription factors interacting with at least three DNA control elements: G1, the upstream promoter element, and G2 and G3, two enhancer-like sequences. We report here that the major enhancer of the rat glucagon gene, G2, interacts with three protein complexes, A1, A2, and A3. A2 is detected only in islet cells, and impairment of its binding to mutant G2 causes a marked decrease in transcriptional activity. We identify A1 as hepatocyte nuclear factor 3 beta (HNF-3 beta), a member of the HNF-3 DNA-binding protein family found in abundance in the liver which has been proposed to play a role in the formation of gut-related organs. HNF-3 beta binds G2 on a site which overlaps A2 and acts as a repressor of glucagon gene expression, as demonstrated by mutational analyses of G2 and by cotransfection of HNF-3 beta cDNA along with reporter genes containing G2 into glucagon-producing cells. Our data implicate HNF-3 beta in the control of glucagon gene expression and strengthen the idea of endodermal origin of the islet cells.

Animals↗
PubMed1994

[Treatment of coloboma pitS of the optic nerve complicated by serous detachment of the neuroepithelium].

PURPOSE: The pathogenesis of the sensory retinal detachment of the macula associated with congenital pit of the optic nerve remains controversal. Based on our cases and the cases reported in literature, we propose a management plan for macular retinal detachment associated with optic nerve pit. METHODS: In this retrospective study ten eyes were treated for progressive visual loss. Treatment modalities were different depending on the time period: laser photocoagulation (to the juxtapapillary region) alone, laser combined with intraocular gas injection (C3 F8), laser combined with vitrectomy and intraocular gas tamponnade (S F6, C3 F8), laser combined with vitrectomy and temporary silicone oil tamponade. RESULTS: The follow-up period ranged between one and five years (mean follow-up thirty three months). We had eight successes and two definitive failures (an old macular detachment treated only by one laser session, and a young girl who had not kept the prone position after gas injection). In the group of six eyes treated by laser alone, only two retinal treatments were directly successfully treated; in three other eyes, the detachment recurred and was treated with success in a second step by a gas injection; the sixth eye is the first definitive failure (old detachment). In the five eyes treated by laser combined gas injection with or without pars plana vitrectomy (including three failures of laser alone), the retina remained attached in four eyes during the follow-up period; the sixth eye was the second definitive failure (the young girl). In the both eyes treated by vitrectomy and silicon oil injection, the retina has flattened. CONCLUSION: The results suggest that laser photocoagulation alone is not so efficient and that vitrectomy is not necessary with gas injection. Complete resorption of subretinal fluid occurred in eight eyes: two with laser photocoagulation alone, and six with a long term tamponnade combined with a peripapillary laser photocoagulation. In first treatment, this technique (laser with tamponade) is a valuable approach to manage serous macular detachment associated with optic nerve pit.

Adolescent↗