PubMed Health⌕ Search

Biomedical subjects

Y Morin

Publications and source records attributed to Y Morin.

At least 19 recordsLinked to original sources
PubMed2005

Acetylcholine release is elicited in the visual cortex, but not in the prefrontal cortex, by patterned visual stimulation: a dual in vivo microdialysis study with functional correlates in the rat brain.

By its projections to the primary visual and the prefrontal cortices, the basal forebrain cholinergic system is involved in cognitive processing of sensory stimuli. It has been suggested that visual stimulus-induced cholinergic activation of the visual cortex may exert a permissive role on thalamocortical inputs. However, it is not known if visual stimulation elicits cholinergic activation of high-order brain areas in the absence of attentional need. In the present study, we measured the effects of patterned visual stimulation (horizontal grating) on the release of acetylcholine with dual-probe in vivo microdialysis in the visual and the prefrontal cortices of anesthetized rats. We also used retrograde tracing to determine the anatomical relationships of cholinergic neurons with neurons of the visual system and the prefrontal cortex. Finally, we evaluated a functional correlate of this stimulation, namely c-fos immunolabeling. Patterned visual stimulation elicited significant increases in acetylcholine release in the visual cortex, accompanied by an increased number of c-fos immunoreactive neurons in this brain area. In contrast, in the prefrontal cortex, neither the level of acetylcholine release nor the number of c-fos immunoreactive neurons was significantly changed because of the stimulation. Cholinergic basal forebrain neurons projecting to the visual or the prefrontal cortices were both localized within the horizontal limb of the diagonal band of Broca but were not immunoreactive for c-fos during visual stimulation. No parts of the visual system were found to directly project to these basal forebrain neurons. These results suggest the differential involvement of cholinergic projections in the integration of sensory stimuli, depending on the level of activity of the targeted cortical area.

Acetylcholine↗
PubMed2003

Contrasting changes of sensitivity by lymphocytes and neutrophils to mercury in developing grey seals.

Mercury is the principal metal contaminant in the St Lawrence Estuary. It impairs humoral, cellular and non-specific immune responses in many species. Since the immune system of juvenile seals is immature, it should react differently to the effects of contamination compared to that of mature animals. Phagocytosis and lymphoblastic transformation responses have been evaluated in the peripheral blood leukocytes of eight juvenile grey seals at different intervals of time over 11 weeks. Dose-response curves of 10(-9)-10(-3)M of methylmercury chloride have also been performed in vitro for evaluation of these two immune functions. The immune response of grey seals differs during their development. The phagocytosis response increased from the 2nd to 5th week post-weaning and then reached a plateau. As for the lymphoblastic transformation response, it was stable from the 2nd to the 3rd week post-weaning, increased significantly at week 4 post-weaning and then reached a plateau. These data suggest that these animals should be particularly vulnerable to infections, diseases and parasites before the 5th week post-weaning. Furthermore, mercury decreased the immune response, and age of seals had an effect on cell sensitivity to mercury. Concentrations of 10(-5)M of methylmercury chloride decreased phagocytosis and lymphoblastic transformation responses. Phagocytosis is more affected by MeHgCl contamination before this immune function reaches complete development which occurs at week 5 post-weaning. On the other hand, lymphoblastic transformation is more affected by this contaminant after its complete development which occurs at week 4 post-weaning.

Age Factors↗
PubMed2003

[Tubulo-interstitial nephritis and uveitis (TINU syndrome): a new pediatric case].

TINU is a rare disease of unknown etiology that associates acute tubulointerstitial nephritis and uveitis in a context of systemic symptoms (asthenia, weight loss, fever) and inflammatory biological signs. We report a new case in a 10-year-old girl with unilateral uveopapillitis and renal insufficiency caused by interstitial nephritis (creatininemia: 225 micro mol/l). Complete recovery was obtained with high-dose systemic corticotherapy, with the patient remaining free of disease 2.5 years after the end of treatment. The disappearance of renal lesions was histologically verified.

Anti-Inflammatory Agents↗
PubMed2002

Effects of exposure of Mya arenaria and Mactromeris polynyma to contaminated marine sediments on phagocytic activity of hemocytes.

Two species of bivalves, Mya arenaria and Mactromeris polynima, were exposed to contaminated marine sediments from Baie des Anglais, Quebec, for a period of 10 and 12 weeks, respectively, in order to determine if there was an effect on the phagocytic activity of hemocytes from each species. These sediments contain elevated levels of both PAHs and PCBs. Uncontaminated beach sand was used as control sediments. After a period of 4 weeks, each species of bivalves were sampled and hemocyte phagocytic activity was monitored by flow cytometry. While phagocytosis by hemocytes from M. polytiyma was significantly suppressed, those from M. arenaria were not different from beach sand-exposed controls. At the end of the exposure period, the phagocytic activity of hemocytes from both species was suppressed. Physiological parameters such as mantle proteins or malondialdehyde levels, total protein and total glycogen levels in the digestive gland were not affected by exposure to contaminated sediments. Moreover, the suppression of phagocytosis was well correlated with the transfer of contaminants from the sediments to the bivalves and their subsequent bioaccumulation, as demonstrated by the PCB body burden. These results support the use of bivalves as good sentinel species to survey sediment contamination and the usefulness of hemocyte phagocytic activity as a sensitive biomarker of exposure to organic contaminants.

Animals↗
PubMed2002

Phagocytic activity of marine and freshwater bivalves: in vitro exposure of hemocytes to metals (Ag, Cd, Hg and Zn).

We measured non-specific immune function of various bivalves from marine (Cyrtodaria siliqua, Mactromeris polynyma, Mesosdesma arctatum, Mya arenaria, Mya truncata, Mytilus edulis, Serripes groenlandicus, Siliqua costata) and freshwater environments (Dreissena polymorpha and Elliptio complanata). We used flow cytometry to quantify the phagocytosis of fluorescent microspheres by hemocytes exposed in vitro to increasing levels of various metal compounds (AgNO(3), CdCl(2), CH(3)HgCl, HgCl(2) and ZnCl(2)). In some species, low doses of mercury (organic and inorganic) and Zn suggest a hormesis-like stimulation of phagocytic activity. At higher levels of exposure, all metals tested induced a significant dose-related inhibition of hemocyte phagocytosis. The species-specific sensitivity of the assay was determined by comparing the in vitro exposure using the metal concentration inducing a 50% suppression (EC(50)) of the phagocytic activity. Different species expressed different levels of sensitivity. Our results show the variability of the toxic response of different species within a group of similar organisms. It also highlights the need to consider species-species differences in ecotoxicological risk assessment.

Animals↗
PubMed2001

Effects of in vivo exposure of Mya arenaria to organic and inorganic mercury on phagocytic activity of hemocytes.

Marine bivalves are aquatic invertebrate organisms which can be used as bioindicators in environmental monitoring. In vivo effects of mercuric chloride (HgCl(2)) and methylmercury (CH(3)HgCl) on phagocytic function of Mya arenaria hemocytes were evaluated in this study. Clams were exposed to single metal in water for up to 28 days at concentrations ranging from 10(-9) to 10(-5) M. Phagocytic activity of hemocytes was determined by uptake of fluorescent microspheres and flow cytometry. All clams exposed to 10(-5) M HgCl(2) died by day 7 of exposure. The viability of hemocytes was decreased only in clams exposed to 10(-6) M HgCl(2) for 28 days. A significant decrease in phagocytic activity of hemocytes was observed in clams exposed to 10(-6) M of HgCl(2) for 28 days. A similar pattern was observed with CH(3)HgCl, but at an earlier time. Chemical analysis performed on the tissues of the animals clearly show a greater uptake of the organic form of mercury by clams. Furthermore, a clear correlation was established between body burden of mercury and effects on phagocytic activity of hemocytes. Overall, the results of this study show that both speciations of mercury inhibited phagocytic function of Mya arenaria hemocytes following in vivo exposures.

Animals↗
PubMed2000

Flow cytometry as a tool to monitor the disturbance of phagocytosis in the clam Mya arenaria hemocytes following in vitro exposure to heavy metals.

The effectiveness of toxicology biomonitoring programs could be improved by the addition of sensitive biomarkers. In this study the cell viability and sensitivity of phagocytic function of phagocytes from bivalves (Mya arenaria) to selected heavy metals were measured by flow cytometry, a novel approach. Hemocytes (phagocytes) collected from bivalves by puncture of the posterior adductor muscle were incubated in vitro for 18 h in hemolymph containing 10(-9)-10(-3)M of cadmium chloride, zinc chloride, mercuric chloride, methylmercury chloride or silver nitrate, before determining their capacity to phagocytose fluorescent latex beads by flow cytometry. Heterogeneity of the hemocyte cell population was determined by forward scatter (FSC) and side scatter (SSC) cytometric profile which showed two distinct cell populations. At low doses (10(-9), 10(-8) M), all the metal compounds studied stimulated phagocytic activity except silver nitrate. At higher levels of exposure (10(-6), 10(7) M), all metals caused a significant concentration-related decrease in hemocyte phagocytosis activity. From the concentration of each metal inducing 50% suppression (IC50) of the phagocytic activity, the immunotoxic potential of metals with respect to phagocytic function can be ranked in the following increasing order: ZnCl2 < CdCl2 < AgNO3 < HgCl2 < CH3HgCl. Parallel analysis of hemocyte viability showed that suppression of phagocytosis by heavy metals was not solely related to a decreased cell viability. These results reveal the high but different degree of sensitivity of the phagocytosis activity of bivalves with respect to heavy metals, as measured by flow cytometry, and demonstrate that flow cytometry is a potentially useful tool in ecotoxicological monitoring.

Animals↗
PubMed2000

[Hepatocellular carcinoma: a case revealed by metastatic orbital tumor].

INTRODUCTION: We report a case of metastatic orbital tumor revealing hepatocellular carcinoma. EXEGESIS: Metastatic orbital tumors of hepatocarcinoma are rare. Only six cases have been reported. We compare these cases to our observation. Treatment of the orbital metastasis is important to decrease pain, ophthalmological symptoms and to improve the quality of survival. Radiotherapy and/or surgery can be used. Prognosis for life depends on liver involvement: the modalities of treatment of the hepatocarcinoma have to be discussed for each patient. CONCLUSION: Seven cases of orbital metastasis revealing a hepatocarcinoma have been documented. Effectiveness of radiotherapy makes the local prognosis good, but prognosis depends on liver involvement, since prognosis of hepatocellular carcinoma is poor.

Carcinoma, Hepatocellular↗
PubMed2000

Effects of five insecticides used in apple orchards on Hyaliodes vitripennis (Say) (Hemiptera: Miridae).

Azinphos-methyl, carbaryl, dimethoate, phosmet and phosalone were used in apple orchards to manage apple aphid, apple maggot, woolly apple aphid and leaf eating caterpillars. Among the five insecticides evaluated, dimethoate, carbaryl and azinphosmethyl were the most toxic to the nymphs and adults of Hyaliodes vitripennis (Say) from two regions. Phosalone was the least toxic. Nymphs were more resistant than the adults. While the LC50 for dimethoate was 130 ppm for nymphs, it was 3 ppm for adults from St. Jean-Baptiste-de-Rouville. There were also significant differences in the level of resistance between the two regions where the H. vitripennis were collected. At St. Alexandre the LC50 for phosalone on nymphs was 19,250 ppm whereas, at St. Jean-Baptiste-de-Rouville it was 160,000 ppm.

Agriculture↗
PubMed1995

Three-month efficacy and safety of once-daily diltiazem in chronic stable angina pectoris.

The 3-month efficacy and safety of a once-daily controlled formulation of diltiazem (180 to 360 mg/day) were assessed in a study of 54 patients with angina pectoris. This multicenter study was a nonrandomized, placebo run-in, open-label, 3-month trial followed by a 1-week, double-blind, randomized period during which most patients (89%) received placebo. There were only minimal changes in the time to termination (mean change +/- SEM -5.8 +/- 9.6 seconds), time to onset of angina (10.5 +/- 12.2 seconds), and the time to 1 mm ST-segment depression (2.9 +/- 12.5 seconds) from the end of the titration phase to the end of the open-label study. There were, however, statistically significant differences between the end of the 3-month treatment phase and the end of the 1-week randomized placebo phase for those 3 efficacy parameters (-37.3 +/- 11.2, -58.6 +/- 13.6, and -45.6 +/- 16.4 seconds, respectively). Diltiazem significantly decreased the frequency of anginal attacks and nitroglycerin use at the end of the 3-month treatment phase compared with results at the end of the randomized double-blind placebo phase. No new or unusual adverse events were reported during treatment. The present results suggest that there is no loss of efficacy of once-a-day diltiazem when administered for a long period to patients with chronic stable angina pectoris.

Aged↗
PubMed1995

[Unexplained bilateral optic disk edema. So-called idiopathic intracranial hypertension of drug origin should be suspected].

In 2 clinical cases of bilateral optic disk oedema, the optic disk oedema was part of a so-called benign, or rather idiopathic, intracranial hypertension. Aetiological investigations were unable to detect any intracranial or systemic anomaly, except the fact that both patients had been on a long-term treatment. The first, a 35-year-old man, was taking Roaccutane (isotretinoin) for acne, for at least 5 years, Supradyne (containing vitamin A) minimum 1 pill per day. The second patient, aged 16 years, had also been treated for acne with Roaccutane and Mynocine (minocyclin) for several months. Minocyclin and vitamin A, contained in these substances, are likely to have induced the idiopathic intracranial hypertension, and consequently the optic disk oedema. Indeed, discontinuing the treatment and rachicentesis led to a significant resolution of symptoms. A good history of the clinical cases thus remains a key-element in the process of diagnosis-making and should be strictly conducted in cases with bilateral optic disk oedema, particularly when seen in young patients.

Adolescent↗
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

[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

[Clinical and epidemiological aspects of Horton disease based on survey methods in ophthalmology or internal medicine].

We conducted a retrospective study of 29 consecutive cases of temporal arteritis, all with definite histological diagnostic criteria. The epidemiological aspects of the main clinical and biological features were compared according to their mode of recruitment, the patients being hospitalized either in an ophthalmological unit (n = 15), or in an Internal Medicine unit (n = 14). The level of fever and of sedimentation rate were significantly less in the ophthalmological group (respectively p < 0.001 and p < 0.02), a third of which is represented by the purely ophthalmological manifestation called "occult temporal arteritis". Among the ophthalmological manifestations, despite the fact that the recruitment bias prevented any strict epidemiological comparison, we were surprised to find no significant difference between the two groups concerning the frequency of transient ophthalmological manifestations, which confirmed in half the patients their reputation of forerunners of irreversible lesions. Thus, the presentation of temporal arteritis differs according to its ophthalmological or Internal Medicine recruitment. We were unable to determine a precise chronology difference in the principal manifestations between these two groups. The severity of the ocular manifestations justifies looking for temporal arteritis in all cases of transient ophthalmological manifestations, even if clinically totally isolated.

Aged↗
PubMed1993

[Definitive transient monocular blindness caused by ocular compression during general anesthesia].

We present a case of irreversible monocular blindness caused by obstruction of the central retinal artery detected in a young patient without any previous history, when waking up from a surgical procedure performed under general anesthesia. Clinical and complementary investigations were not conclusive. Nevertheless, when inquiring on the surgical procedure, it appeared that the patient was lying in a procubitus position, so that his head may have slipped on the head support, resulting in compression on his right eyeball. The fact that the patient was simultaneously submitted to a controlled low blood pressure may have worsened the effects of the compression. Reviewing the medical literature on the subject reveals that, although rare, such accidents do occur; they must be prevented by a constant surveillance when performing surgical procedures.

Adult↗
PubMed1989

[Efficacy of spiramycin and tylosin in preventing mycoplasmosis in chicks experimentally infected with mycoplasma gallisepticum].

In order to evaluate the activity of two drugs (spiramycin and tylosin), one-day-old chicks are inoculated with a virulent strain of Mycoplasma gallisepticum (MG) and given spiramycin (3 different doses) or tylosin (1 dose) for two or three days. Effectiveness is assessed on different criteria: mortality, symptoms, weight gains, gross lesions, MG tracheal recovery and serology. Results show that spiramycin and tylosin have the potential of reducing mortality, symptoms and lesions. Weight gains of treated birds are greater than those of infected untreated birds. However, MG was recovered from tracheas of all treated birds.

Ammonium Chloride↗
PubMed1988

[Tolerability in ophthalmologic surgery of CY 216 in preventing venous thrombosis of the leg].

The specificity of the action of low-molecular-weigh heparin promotes its prevention use in ophthalmological surgery, where any hemorrhage, even if not of vital consequence, can reduce and even cancel out the results of the surgery. Consequently, we subjected 63 patients (21 male, 42 female) aged 54 to 93 to preventive treatment with Fraxiparine (CY 216) as per the conventional indications of risk factors: essentially venous insufficiency [23], varicose veins [29], a history of phlebitis [20] or pulmonary embolism [12]. A first group of 31 patients (protocol P 1) was given the first injection 2 hours prior to surgery (D 0). A second group of 32 patients (P 2) was given the injection at 10 p.m. on the eve of surgery (D-1). P 1 and P 2 were given CY 216 (0.3 ml, one injection at 6 a.m.) each day from D 1 to D 7 (and 7 patients from P 1 until D 10). The type of surgery concerned was: cataract [46], retinal detachment [11], glaucoma [3]; fifteen patients had already undergone surgery and 6 were given CY 216 twice. P 2 was compared with a control group T of 20 patients (7 male, 13 females, mean age 71.8) in the same department given calcium heparin sc (3 x 0.2 ml daily, D 1 to D 7). In P 1 and P 2, as well as in the T group, no clinical thromboembolic complications were observed. Tolerance, however, differed. In P 1: 2 cases of hyphema and one of choroidal hematoma. In P 2: no significant hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗