Biomedical subjects

C Mercier

Publications and source records attributed to C Mercier.

At least 109 records · Page 6Linked to original sources

PubMed1993

Influence of electrical stimulation on enzymatic activity of old rat muscles during hindlimb suspension.

1. The purpose of this study was to determine the effects of electrical stimulation on the muscles of older rats (21-24 months old) during suspension hypokinesia/hypodynamia. The rats' hindlimbs were suspended for three weeks, after which the activities of three enzymes were measured in the extensor digitorum longus, the medial gastrocnemius and the soleus muscles. 2. The activity of phosphofructokinase decreased in the soleus muscle and in the white part of the medial gastrocnemius muscle. Malate dehydrogenase and beta-hydroxyacyl-CoA-dehydrogenase showed decreased activity in the red part of the medial gastrocnemius muscle. 3. When electrical stimulation was applied, the activity of the glycolytic enzyme phosphofructokinase increased substantially in all studied muscles. The activity of the malate dehydrogenase and beta-hydroxyacyl-CoA-dehydrogenase enzymes was not influenced by electrical stimulation in the majority of the studied muscles. 4. These results suggest that our electrical stimulation model not only prevents loss of phosphofructokinase activity of aged muscles but increases the activity of anaerobic glycolysis metabolism without affecting the oxidative and fatty acid pathways.

Aging↗

PubMed1993

Molecular structure of a Toxoplasma gondii dense granule antigen (GRA 5) associated with the parasitophorous vacuole membrane.

The P21 antigen of Toxoplasma gondii, defined by the monoclonal antibody TG17-113, has been described as a dense granule component, secreted in the parasitophorous vacuole during host cell invasion. The present work reports the cloning of the gene encoding the P21 antigen, for which we propose the name GRA 5. A cDNA library was screened with a rat antiserum raised against an HPLC fraction enriched in the P21 antigen. cDNA clones encoding GRA 5 were selected by antibody selection on the recombinant proteins. All these clones were incomplete at the 5' end. The 5' fragment of the longest cDNA clone isolated by this first screening was used as a probe in secondary screenings of cDNA and genomic DNA libraries. A genomic fragment containing the P21 gene and nearly full-length cDNAs have been isolated and sequenced. The gene encoding GRA 5 is 834 bp long and does not contain any intron. The deduced amino acid sequence of an open reading frame encoding 133 amino acids perfectly matched that of 5 peptides microsequenced from the native antigen. A N-terminal hydrophobic region was found to possess the characteristics of a signal peptide of 25 amino acids. A second hydrophobic domain, bordered by two hydrophilic regions strongly suggests a transmembrane region. This molecular structure is supported by ultrastructural studies showing the association of the P21 antigen with the parasitophorous vacuole membrane.

Amino Acid Sequence↗

PubMed1993

Molecular characterization of a dense granule antigen (Gra 2) associated with the network of the parasitophorous vacuole in Toxoplasma gondii.

The monoclonal antibody (mAb) TG17.179 recognizes an excreted-secreted antigen (ESA) of 28.5 kDa named Gra 2, which is stored in the dense granules of Toxoplasma cells and secreted into the parasitophorous vacuole after host cell invasion. Screening of an expression cDNA library with TG17.179 led to the isolation of several clones, the longest one (clone L) being of 1030 bp. Clone L cDNA was found to be homologous to a previously described composite cDNA encoding a P28 protein of Toxoplasma gondii. Characterization of one genomic clone indicates that the complete GRA 2 gene is about 1.3 kb in length, including an intron of 241 bp. Northern blot and primer extension analyses confirmed the size of the mature messenger (1.1 kb). Amino acid partial sequencing of the native antigen purified by HPLC and metabolic radiolabelings of ESAs perfectly matched the primary amino acid structure deduced from the clone L cDNA. This primary translation product consists of an 185 amino acid polypeptide (19.8 kDa) including a 23 amino acid signal sequence. The presence of many serine and threonine residues may indicate an O-glycosylation. The predicted mature polypeptide shows an internal helical domain with 2 amphipathic alpha-helices. These might be involved in the association of Gra 2 with the membranous network within the parasitophorous vacuole.

Amino Acid Sequence↗

PubMed1993

Tailgut remnant--or teratoma?

The tailgut is the distalmost portion of the embryonic gut, located caudal to the cloacal membrane. Up to the sixth week of development, it is in close proximity to the distal end of the notochord and the neural tube. It completely regresses by the seventh week, but some caudal duplication-like cysts have been attributed to its remnants. We report a full-term male born with a large heterogeneous sacral mass. Severe bony abnormalities of the coccyx, sacrum and lower lumbar vertebrae were present, but the infant was neurologically intact. At surgery, the upper cystic structures within the mass were found to communicate with the dura, while the solid component, whose surface resembled intestinal mucosal folds, was closely related to the perirectal tissues. The mass was completely resected and the dura oversewn. Since this complex mass contained all three cell lines in an aberrant location, it satisfies the definition of a sacrococcygeal teratoma. However, its unique architecture suggests a malformative, rather than tumoral origin. The macroscopic appearance of this lesion reflects the embryonic relationship between the tailgut, the neural tube and the notochord.

Diagnosis, Differential↗

PubMed1993

ACE inhibition with perindopril and atherogenesis-induced structural and functional changes in minipig arteries.

The effects of angiotensin-converting-enzyme (ACE) inhibition on atherosclerosis-induced changes in arterial function are unknown, as well as whether they are coupled to improvements of structural alterations in the arterial wall. An atherogenic (A) diet and the ACE inhibitor perindopril (P) were given concomitantly for 4 months to seven adult Pitman-Moore minipigs (7 months of age; A+P animals), which were compared with seven A and seven control (C) animals. Perindopril, at a daily dose of 4 mg PO that is commonly used in the clinical setting, induced a continuous 70% inhibition of serum ACE activity. At the end of the study, the atherosclerosis-induced impairment of arterial flow was investigated via the hemodynamics and vascular rheology of hindlimb arteries in non-barbiturate-anesthetized pigs. Structural alterations were evaluated from the histopathology of lesions in the arterial tree (abdominal aorta, left interventricular coronary artery [LIVCA], and brachiocephalic trunk [BCT]), with particular attention given to the analysis of the structure and composition of aortic elastic fibers. Atherosclerosis impaired the function of both capacitance and resistance arteries. Blood pressure (BP) rose significantly because of increased hindlimb peripheral resistance (HPR) and aortic input impedance (Zc), although blood flow was not affected. Altered aortic stress and elastic responses revealed that the stiffness of the aorta was markedly increased because of increased wall tension and reduced viscoelasticity, the viscous component being blunted in the arterial wall. Perindopril significantly opposed these alterations by reducing BP, HPR, and Zc and by returning parietal stiffness values to C values by increasing aortic compliance. ACE inhibition prevented the alteration of both stress and elastic responses. Major fibroproliferative fatty lesions were observed in the aorta and LIVCA, while moderate fibrosclerotic lesions were found in the BCT. Computerized densitometric analysis of orcein-stained elastin showed that elastic laminae fragmentation was prominent in the abdominal aorta, less in the LIVCA, and moderate in the BCT. Furthermore, the elastin content was reduced in the atherosclerotic aorta, although this loss of elastin was not associated with changes in the biochemical nature of alkali-insoluble elastin. Perindopril significantly prevented the development of atherosclerosis in the abdominal aorta, LIVCA, and BCT by decreasing the cross-sectional area of lesions as well as the number of lipid-laden cells in the abdominal aorta and LIVCA. In the abdominal aorta, ACE inhibition significantly prevented the alteration of elastic laminae by specifically preventing elastolytic fragmentation of dense elastic laminae, but it didn ot modify elastin content.(ABSTRACT TRUNCATED AT 400 WORDS)

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1993

{A pro-active approach to community intervention in the rural setting}.

This paper reports an evaluation study of a pilot project held in a "CLSC" (Local Community Health Centre) located in a rural community. The intervention design is based on multidisciplinary teams created to meet specific local community needs. Mental health intervention is part of a community-based approach open to all kinds of requests for support. Practitioners in the field give support not only to the individual with a mental health problem, but also to existing self-help networks in the community. The intervention is also designed to change the relationship between a professional, seen as the one who provides services, and a client, defined as a consumer. The term "client" gains a wider meaning, and collaborative work with informal self-help networks induces a closer relationship between the community and the practitioner. The practitioner is more open to local community values and adjusts his or her practice to match variable contexts. The evaluation study has expanded knowledge of this type of intervention design, on its impact upon service demand, intervention modalities, and service management and organization. This project was coupled with a similar project in an urban environment and was financed by the Health and Social Services Ministry in Québec.

Community Mental Health Services↗

PubMed1993

Multiple B-cell epitopes in a recombinant GRA2 secreted antigen of Toxoplasma gondii.

Two cDNA clones encoding the GRA2 (G.P.28.5) secreted antigen of Toxoplasma gondii were expressed in Escherichia coli as glutathione-S-transferase fusion polypeptides. A high level of expression was obtained for the first clone expressing the 59C-terminal amino acids of GRA2. The other one was an open-reading-frame of 212 amino acids containing the entire GRA2 cDNA. By ELISA, IgG antibodies directed against the 59aa recombinant polypeptide were detected in 33/44 (75%) sera from patients chronically infected with T. gondii and in 19/23 (82.6%) sera derived from patients with acute, primary toxoplasmosis. 10 of the 11 "chronic" sera which were negative by the 59aa ELISA were tested in a immunoblot against the 212aa open-reading-frame of GRA2: 8/10 were positive. A peptide representing the 15 C-terminal amino acids of GRA2 has been shown to contain the epitope recognized by a mouse monoclonal antibody (TG17-179). The reactivity of human sera with the 59aa recombinant polypeptide was inhibited to varying degrees when the sera were co-incubated with this peptide. Twelve chronic sera showed a range of inhibition from 8 to 100% and twelve acute sera an inhibition range of 15 to 90%. This suggests that the 15aa C-terminal peptide contains an epitope recognized in both the acute and chronic phases of infection and that other major epitope(s) exist in the 59aa C-terminal region of GRA2. As a conclusion, the recombinant GRA2 protein appears to contain at least three B-cell epitopes.

Acute Disease↗

PubMed1993

Extension of a cerebellar cystic astrocytoma into the cervical canal, demonstrated by magnetic resonance imaging.

One characteristic feature of ependymomas of the fourth ventricle is a tendency to extend through the foramina, specifically the foramina of Luschka and Magendie, the foramen magnum and the aqueduct of Sylvius. The authors report a case of pilocytic astrocytoma of the cerebellum that mimicked such extension into the upper cervical canal. This finding was revealed by magnetic resonance imaging and confirmed at surgery.

Astrocytoma↗

PubMed1992

Fibromuscular disease of the renal artery: a new histopathologic classification.

To evaluate the relationship between clinical, radiologic, and histopathologic features in various types of renal artery fibromuscular disease, the records of 37 patients operated upon for a total of 44 lesions of the renal artery (30 unilateral and seven bilateral) were retrospectively reviewed. Of these, 36 had hypertension associated with stenosis or aneurysm of the trunk or branches of the renal artery; one had aneurysm of the renal artery without hypertension. The histopathologic study included 38 arterial segments retrieved from 33 patients and underscored the difficulties in using topographic criteria to classify lesions. While all arterial aneurysms were associated with involvement of the media, more than one layer of the artery was involved in 65.7% of cases. Topographic forms, such as the perimedial type, were difficult to classify. Based on the study results, it appears essential to distinguish patients with fibrosis and smooth muscular hyperplasia (type I: 19 patients, 23 arteries) from patients with isolated fibrosis (type II: 14 patients, 15 arteries). In group II, preoperative hypertension was more long-standing (p less than 0.04), more lesions were extended distally (p less than 0.05), and the probability of recovery from hypertension at 52 months follow-up was lower. We have distinguished two different evolutive stages of fibromuscular disease of the renal artery, one characterized by fibrosis with smooth muscle hyperplasia and the second, associated with more severe prognosis, characterized by isolated fibrosis.

Anastomosis, Surgical↗

PubMed1992

Amino acid sequence requirements for the epitope recognized by a monoclonal antibody reacting with the secreted antigen GP28.5 of Toxoplasma gondii.

We have characterized in detail, the epitope of the secreted antigen GP28.5 recognized by the mouse monoclonal antibody TG 17-179 using synthetic peptides and a truncated recombinant fusion protein. The screening of a T. gondii expression library with TG17-179 mAb led to the isolation of cDNAs clones, all encoding for the C-terminal region of GP28.5 and with one encoding for only the five last C-terminal residues. Competitive ELISA with longer peptides revealed that the immunoreactivity was retained for peptides of eight residues or longer, and lost when the peptide was reduced to the six last C-terminal residues or less. Experiments with the octapeptide lacking the carboxy-terminal glutamine residue showed it to be 64-fold less active. Moreover, neither addition of residues in the carboxy-end nor substitution of COOH function changed the immunoreactivity of the epitope. Competition experiments between TG17-179 mAb and sera from infected individuals demonstrates that the epitope defined by a mouse monoclonal probe is also a major epitope for human polyclonal antibodies. These results describe the sequence requirements within a probably linear epitope and give rise to some general question concerning experimental test for epitope mapping.

Amino Acid Sequence↗

PubMed1992

[Postoperative re-expansion causing unilateral pulmonary edema].

A case of re-expansion pulmonary oedema is reported. A 7-year-old girl, after having been operated on for a lung tumour, had a postoperative haemothorax combined with atelectasis of the left upper lobe. After she had recovered from the first dose of chemotherapy, the thoracotomy wound was reopened to remove the partially organised and lysed haemothorax, as well as the very thickened pleura. The patient developed clinical signs of pulmonary oedema very shortly after the end of the anaesthetic (tachypnoea, cyanosis, a decrease in oxygen saturation when FIO2 < 1, pink frothy secretions in the endotracheal tube). End-inspiratory crepitations became audible in the left lung field only. The chest film showed left-sided diffuse nodular alveolar opacities. The girl was again ventilated, with + 5 cmH2O positive end-expiratory pressure. She was extubated 36 h later, and discharged a few days later without any sequela. This case was the first to be described in a child after pleural surgery. The death rate, estimated from a literature survey, is about 20%.

Child↗

PubMed1992

[Community services and quality of life: a study of the impact in a remote region].

This longitudinal study with a matched comparison group was conducted in Abitibi, an area in North-West Quebec. Its goal was to observe the impact of community support services on the quality of life of long term psychiatric patients living in a remote area. A cohort of 47 subjects, living in a small town with a comprehensive network of community support services, was compared with a similar group living in a neighbouring city with only outpatient services. The satisfaction with life domains scale developed by Andrews and Withey and adapted by Baker and Intagliata was used at four times during the study. According to the results, the subjective perception of the quality of life in the two groups is comparable, even though the objective conditions are less favorable for the group participating in the community support program. The highest ratings were given to the place of residence, the neighborhood and its commodities; the lowest ratings were given to their love life and financial situation. One can observe a stability of the measures of quality of life over time and for the two groups. The perceptions of the sample living in a remote area are much more favorable than the ones of a comparable group living in the Montreal area. These results are discussed in a double perspective: the role of community support services in the daily life of people who are having severe and persistent problems of mental health, and the interest of measures of quality of life.

Adult↗

PubMed1992

Profiles of alcoholics according to the SCL-90-R: a confirmative study.

The Symptom Checklist-90-Revised (SCL-90-R) has often been used in studies of alcoholic populations. Based on findings reported in the literature and data gathered on 712 alcoholics in treatment, this paper investigates the general trends in the responses of alcoholics to the SCL-90-R. On global measures as well as on each of the symptom scales, the scores of alcoholic groups reveal a symptomatology two to five times as severe as that observed in the general population. The Psychoticism dimension shows the most marked divergence with the general population. In almost each of the study groups, the Depression Scale registers the highest scores, followed by Obsessive-Compulsive, Interpersonal Sensitivity, and Anxiety.

Adult↗

PubMed1992

Intramedullary epidermoid cysts of the spinal cord. Case report.

Epidermoid cysts are tumors familiar to neurosurgeons, but intramedullary epidermoid cysts are rare. The authors report the case of a 6-year-old girl presenting with progressive paraparesis. A midthoracic intramedullary mass was revealed on myelography and magnetic resonance (MR) imaging and confirmed as an intramedullary epidermoid cyst at surgery, at which time the cyst was removed. This is the fourth report documenting a purely intramedullary epidermoid cyst occurring in a child. The pathology and etiology, epidemiology, clinical features, radiology (including MR image characteristics), and surgical treatment of such rare intramedullary benign tumors are discussed. Magnetic resonance imaging reduces the delay in diagnosis of spinal cord tumors but should be guided by clinical judgment.

Child↗

PubMed1992

[Inhibitors of angiotensin-converting enzyme and processus of intima proliferation in atherosclerosis].

The renin angiotensin system is a negative feed-back system of blood pressure control. A number of concordant experimental and clinical results indicate that the angiotensin family has a trophic effect on the vessel wall. These properties of the angiotensins favorise the proliferation of the cells which make up the vessel wall and also amplify the vascular dysfunction in the absence of the inhibitory regulations. Angiotensin converting enzyme inhibitors could be a valuable therapeutic method of counteracting these deleterious effects on the composition and function of the vessel wall.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1992

[Allografts of cryo-preserved and radio-sterilized spongy bone tissue. Their use in orthognathic surgery].

In some circumstances, the orthognathic surgery creates inter-fragmentary spaces which have to be filled to ensure that the osteotomized segments are wedged and consolidated, and to avoid the appearance of unsightly subcutaneous contours. The authors report the results obtained through the use of cryo-preserved radio-sterilized cancellous bone allografts, coming from femoral heads, used as fillers, in diverse types of osteotomy. Thus, 19 centers of osteotomy have been filled. Follow-up periods ranged from 5 to 20 months. In 8 cases, evidence was made through radiology of the blending of the grafts. The stability of the correction was constantly noticed as well as the perfectly harmonious facial contours, which testifies the osteogenic qualities of this material. No sepsis was observed. It is a quantitatively available material, of easy shaping, the use of which does not lead to a lengthening of the operation, nor to the creation of cutaneous scars. The risk of viral transmission through allografts, specially H.I.V. and hepatitis non A - non B - non C virus is nil due to the radiosterilization.

Adolescent↗

PubMed1991

Human gliomas and epileptic foci express high levels of a mRNA related to rat testicular sulfated glycoprotein 2, a purported marker of cell death.

Clone pTB16 has been isolated by differential screening of a human glioma cDNA library. Northern blot analysis has shown that pTB16 expression is several times (greater than 11-fold) higher in gliomas than in a primitive neuroectodermal tumor. This observation was supported by in situ hybridization and extended to nine other gliomas. Expression was virtually absent in adenocarcinoma cells metastasized to brain. Malignant gliomas showed stronger hybridization than benign gliomas, while blood capillaries did not show hybridization. pTB16 mRNA was also shown to be expressed in established glioma cell lines and at high levels in epileptic foci, indicating that expression of the gene may be limited to certain cell types and that its upregulation is not merely a consequence of cellular proliferation. Nucleotide sequence analysis identified pTB16 as the human counterpart for rat testicular sulfated glycoprotein 2 (SGP-2), whose function in the reproductive system remains unknown. Although SGP-2 transcripts, and hence pTB16, were recently shown to be increased in neurodegenerative diseases such as scrapie in hamsters and Alzheimer disease in humans, our observations with brain tumors and epilepsy are suggestive of a role for pTB16 in neuropathologies in general and support the hypothesis of its involvement in tissue remodeling and cell death.

Blotting, Northern↗

PubMed1991

Unfading acral microlivedo. A discrete marker of thrombotic skin disease associated with antiphospholipid antibody syndrome.

Small erythematous or cyanotic lesions on the hands and feet of four patients with antiphospholipid antibodies are described. These discrete lesions outline capillaries and do not disappear when pressure is applied. The histologic features are identical to those described in skin thrombotic syndrome associated with antiphospholipid antibodies, that is, microthrombi in dermal vessels without inflammation. In addition to indicating antiphospholipid antibodies in apparently healthy patients, this sign could be a marker of risk for large-vessel thrombosis.

Adult↗