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Biomedical subjects

R Lemieux

Publications and source records attributed to R Lemieux.

At least 55 records · Page 3Linked to original sources
PubMed1988

Effect of the elapsed time after the final antigen boost on the specificity of monoclonal antibodies produced by B cell hybridomas.

We have studied the effect of the number of days following the last antigen boost on the specificity of monoclonal antibodies produced by B cell hybridomas using spleen cells of mice immunized with human red cells of the A blood group. We showed, as previously observed by others, that the highest numbers of monoclonal anti-human red blood cells were obtained in fusions done 3 and 4 days after the final boost. However differential screening of the hybridoma cultures showed that the majority of the monoclonal antibodies reacting with the A blood group antigen were obtained in fusions done only 2 days after the last antigen injection. These results show that the delay between the final boost and the fusion experiment can influence not only the total number of antibody-secreting hybridomas but also the specificity of the antibodies produced.

ABO Blood-Group System↗
PubMed1987

Role of the macrophage-derived hybridoma growth factor in the in vitro and in vivo proliferation of newly formed B cell hybridomas.

It has been shown recently that monocyte-macrophage cells produce a growth factor (HGF) active on newly formed B cell hybridomas. We have studied the effect of HGF on the proliferation of an HGF-sensitive clone of B cell hybridoma. Results obtained showed that the murine P388D1 cell-derived HGF has a m.w. of 29,000 and an isoelectric point (pI) of 6.2 whereas the human monocyte-derived HGF has a m.w. of 34,000 and a pI of 4.9. The HGF activity was not mediated by interleukin 1 because the two activities could be completely separated by gel filtration. Results obtained in in vivo experiments showed that HGF-sensitive cells are tumorigenic in mice. The finding that the HGF biochemical parameters (m.w. and pI) are similar to the ones of a recently described plasmacytoma growth factor suggests that HGF and the plasmacytoma growth factor are similar and that the HGF sensitivity of SP 2/O myeloma cells is reactivated after fusion with normal B lymphocytes.

Animals↗
PubMed1987

The viral protein sigma 3 participates in translation of late viral mRNA in reovirus-infected L cells.

Reovirus late (uncapped) mRNA was previously shown to be efficiently translated in vitro extracts prepared from infected cells but not from uninfected cells. We demonstrated that different fractions from infected cells can stimulate translation of late viral mRNA when added to uninfected extracts. The activity of the different fractions correlated with their relative content of the sigma 3 capsid protein; the fraction prepared by high-salt wash of the ribosomes had the highest specific activity. The activity present in this fraction was abolished by preincubation with an anti-sigma 3 serum. Purified sigma 3 protein also stimulated the translation of late viral mRNA, confirming that it was the factor involved. Altogether, these results suggest that this protein plays the role of a late-viral-mRNA-specific initiation factor. The absence of an inhibitory effect of sigma 3 on the translation of other mRNAs indicates that this protein is not directly involved in the inhibition of host and early viral mRNA translation that occurs in infected cells but that a second mechanism is probably operative.

Animals↗
PubMed1986

Protective effect of the membrane skeleton on the immunologic reactivity of the human red cell Rho(D) antigen.

It has recently been shown that the 30,000 m.w. Rho(D) protein is associated with the membrane skeleton of the human red cell. We have studied the effects of the membrane skeleton on the immunoreactivity of the Rho(D) antigen present in Rho(D)+ membranes. Solubilization of the membranes with the Triton X-100 detergent and centrifugation of the extracts showed that more than 90% of the immunoreactive Rho(D) antigen sedimented with the membrane skeleton structures. The skeleton-bound Rho(D) antigen could be solubilized by disruption of the skeleton in low ionic strength medium. The removal of the membrane skeleton structure before the solubilization of the membranes with detergent resulted in the inactivation of the majority of the Rho(D) antigen. The effect of the membrane skeleton on the stability of the Rho(D) antigen was additionally studied in detergent extracts prepared from native and skeleton-free membranes. The assay of the Rho(D) antigen activity in the extracts showed that the Rho(D) antigen was 100 times more sensitive to the detergent inactivation in skeleton-free membranes than in native membranes. These results indicate that the membrane skeleton is important for stabilizing the immunoreactive form of the Rho(D) protein on the red cell membrane.

Antigen-Antibody Reactions↗
PubMed1985

Myocardial infarction diagnosis with body surface potential mapping, electrocardiography, vectorcardiography and thallium-201 scintigraphy: a correlative study with left ventriculography.

In 35 subjects with typical or atypical angina and/or documented myocardial infarction (MI), body surface potential maps (BSPMs), ECG, VCG and rest Thallium-201 (T1-201) have been compared to left ventriculography (LVG). BSPMs were recorded with 26 ECGs, and BSPM abnormalities for MI cases were considered to be areas of normally positive potentials that have become negative. Subjects with MI were classified according to the segmental localization and degree of asynergy on LVG. Moderate anterolateral and apical asynergy were found to correlate with BSPM diagnosis of anterolateral MI and ischemia, severe anterolateral and apical asynergy with BSPM diagnosis of anterolateral MI and ischemia, and moderate diaphragmatic and/or posterobasal asynergy with BSPM diagnosis of posterior MI. Simultaneous anterior and posterior asynergy were found for BSPM diagnosis of anterior with posterior MI. Subjects with no LVG asynergy had normal BSPMs. BSPM diagnosis had the highest correlation coefficient with the LVG diagnosis (r = 0.88). ECG and VCG showed similar results with r = 0.65 and 0.71 respectively, while T1-201 had r = 0.55. The examination of our BSPMs, as well as the ECG, VCG and T1-201, did not permit to detect apical damage in presence of anterior MI, and posterobasal damage in the presence of inferoposterior MI. It is concluded that BSPMs are slightly superior to ECG and VCG for diagnosis of MI.

Adult↗
PubMed1984

mRNA discrimination in extracts from uninfected and reovirus-infected L-cells.

Uncapped reovirus mRNA extracted at late times from infected L-cells is preferentially translated in extracts from infected L-cells. However, translation of this uncapped, late, reovirus mRNA in extracts from infected cells is sensitive to inhibition by the cap analog m7GTP . These results imply that reovirus infection does not induce a transition from cap-dependent to cap-independent translation. Nevertheless, the results of in vitro translational competition experiments between L-cell mRNA and late viral mRNA were consistent with the view that reovirus does induce an alteration in the cap-dependent translational apparatus of L-cells. The reduced efficiency of translation of a variety of capped mRNAs in extracts from infected cells is also consistent with this notion. We further conclude that a factor exists in reovirus-infected L-cells that specifically stimulates translation of uncapped reovirus mRNAs.

Animals↗
PubMed1984

[" Erasme " shelter.].

Having tired of an ineffective hospital practice in the psycho-therapeutic treatment of psychosis, a psychiatrist founds, with health care workers, a therapeutic community where preference is given to the taking in of schizophrenics. The author summarizes the establishment, the mode of operation, the difficulties and the results of the enterprise of ten years duration. He believes that the daily sharing of the same way of life is therapeutic and favours the readaptation to the external world. In addition, it is a shared enrichment in which helper and helpee learn one from the other.

English Abstract↗
PubMed1982

Expression of vaccinia virus early mRNA in Ehrlich ascites tumor cells. 1. Translation of cellular and viral early mRNA in cell-free systems from uninfected and virus-infected cells at the early stage.

Translation of cellular and early vaccinia RNA in nuclease-treated lysates, derived from uninfected and vaccinia-virus-infected cells at the early stage, has been investigated. When using limiting amounts of RNA no discrimination of translation was observed in the infected cells lysates; this conclusion was confirmed by sensitive RNA competition experiments for translation in vitro and also when using two different fractionated systems for protein synthesis in vitro. This absence of detectable discrimination in vitro was established both by comparing incorporation of [35S]methionine into proteins and by analysis of the products thus synthesized by sodium dodecylsulfate gel electrophoresis. However, a modification of the translational machinery from vaccinia-virus-infected cells did occur since the only the ribosomal salt wash derived from infected cells was able to reverse the inhibition of protein synthesis in vitro resulting from excess RNA (control or early). This property of vaccinia-virus-infected cell lysates may result from the synthesis l machinery from vaccinia-virus-infected cells did occur since the only the ribosomal salt wash derived from infected cells was able to reverse the inhibition of protein synthesis in vitro resulting from excess RNA (control or early). This property of vaccinia-virus-infected cell lysates may result from the synthesis l machinery from vaccinia-virus-infected cells did occur since the only the ribosomal salt wash derived from infected cells was able to reverse the inhibition of protein synthesis in vitro resulting from excess RNA (control or early). This property of vaccinia-virus-infected cell lysates may result from the synthesis of an early protein involved in translation or from a better recovery of translational factors from the infected cells, as suggested in the accompanying paper.

Animals↗
PubMed1982

Expression of vaccinia virus early mRNA in Ehrlich ascites tumor cells. 2. Part of the polysomes at an early stage of virus infection are not bound to the cytoskeleton.

A method for preparing detergent cytoskeletons from uninfected or vaccinia-virus-infected cells is described. This method resulted in the fractionation of the cytoplasmic compartment into soluble and cytoskeletal fractions. More than 85% of small molecules and tRNA were released from the cytoskeleton and recovered into the soluble fraction. The cytoskeletal fraction contained about 40% of the cytoplasmic proteins and 67% of total cytoplasmic RNA. Similar values were obtained for vaccinia-virus-infected cells. In contrast, whereas 85% of the cellular polysomes and poly(A)-rich RNA remained associated with the cytoskeleton in uninfected cells, more than 40% of vaccinia early mRNA engaged into polysomes was found to be not associated with the cytoskeleton. A similar partition was found when the viral RNA was labeled for 15 min at 5 min and 20 min after the infection or when varying the duration of the pulse. Soluble and cytoskeletal viral polysomes were found to synthesize a similar set of proteins after translation in vitro of the corresponding mRNA. The fate of rapidly labeled cellular poly(A)-rich RNA upon vaccinia virus infection was followed by a glucosamine/uridine chase procedure, and also that of relatively stable poly(A)-rich RNA after long-term labeling and chase. In both cases no release of poly(A)-rich RNA from the cytoskeleton occurred after vaccinia virus infection. These experiments reveal that cellular mRNA remains associated to the cytoskeleton in EAT cells infected with vaccinia virus (early period) whereas at least 40% of the vaccinia early polysomes are not associated with the cytoskeleton. A model for vaccinia early mRNA metabolism is presented, which may account for the rapid shut-off of host protein synthesis.

Animals↗
PubMed1982

Proteins synthesized by rabbit reticulocyte membrane-bound ribosomes.

Rabbit reticulocyte membrane-bound ribosomes liberated by deoxycholate treatment contain degraded forms of ribosomal and messenger RNA. This degradation occurs after the liberation of the ribosomes from the membranes by the detergent because intact birosomal and messenger RNA can be extracted from washed membranes by phenol treatment. Increasing the ionic strength of the detergent buffer prevents this RNA degradation and allows the recovery of membrane-bound ribosomes capable of protein synthesis. Comparison of the proteins synthesized in vitro by the polyribosomes shows that the main protein produced by both free and membrane-bound ribosomes is globin. However, the two types of polyribosomes could be distinguished by the nonglobin proteins they produce.

Animals↗
PubMed1982

[Group experience : risks and stakes.].

This article presents an experience of an interdisciplinary group crossed by three principal axes : the psychoanalytical field, the socio-cultural and political field, and human sciences research. This adventure led researchers and intervening persons from twenty disciplines to realize projects which are the forms and the means of reappropriation of their own subjective history by their intervention in certain sectors of development of their region. These projects pair research and intervention in the areas of mental health, art and culture. The members of the group give themselves the means to guarantee the viability of these projects in a position of relative independence in relation to traditional institutions.

English Abstract↗
PubMed1980

Lymphocytotoxic definition of combined ABH and Lewis antigens and their transfer from sera to lymphocytes.

Analysis of lymphocytotoxic reactions with peripheral blood lymphocytes from 74 donors, typed for ABO, secretor, and Lewis phenotypes, identified clusters of reactions distinguishing six antigens resulting from the interactions of Lewis, secretor, and ABO systems: Lea, Leb, ALed, BLed, ALeb, and BLeb. In these experiments, Led on O lymphocytes and Lec were not detected as expected from the experience of other authors with A antigen, B and Leb were detected only on the lymphocytes of ABH secretors, demonstrating that all the ABH antigens of lymphocytes are controlled by the secretor system as are the ABH antigens in external secretions. The ABH and Lewis antigens identified on lymphocytes could be transferred in vitro to lymphocytes, cultured for 2 to 7 days at 37 degrees C in the serum of donors of selected ABO, Lewis, and secretor phenotypes, confirming that ABH and Lewis antigens are not synthesized by lymphocytes but are acquired from circulation as are the Lewis antigens on erythrocytes. As expected, the HLA antigens of lymphocytes were not modified after culture.

ABO Blood-Group System↗
PubMed1980

Treatment of diaphyseal femoral fractures.

The results of 104 patients with fractures of the femoral shaft treated, from 1969 to 1973 at the hôpital du Sacré-Coeur in Montreal, by insertion of a large Küntscher nail alone were compared with those in 70 patients whose femoral shaft fractures were treated, from 1960 to 1975 at the hôpital Notre-Dame in Montreal, with a small Küntscher nail and an autologous iliac graft. Use of a large Küntscher nail without bone grafting gave good results in the majority of patients. Excessive reaming, however, diminished the area of contact between the fragments and prolonged the healing time. Refracture occurred more often. The average length of time for consolidation in nongrafted fractures was found to be equal to the maximum time for grafted fractures (i.e., 16 weeks). A small Küntscher nail with an autologous iliac bone graft could be used safely in fractures of the lower third and in the subtrochanteric region of the femur. Grafting produces earlier healing and weight bearing. The hypertrophic callus protects against refracture.

Bone Nails↗
PubMed1977

Technetium-99m glucoheptonate in brain-tumor detection: an important advance in radiotracer techniques.

We have compared [Tc-99m] sodium pertechnetate with Tc-99m glucoheptonate in 52 patients studied for various brain lesions. Flow studies as well as delayed scans were performed in all. Especially in primary and metastatic lesions of the posterior fossa, the diagnostic yield was improved by the delayed glucoheptonate (GH) scans. In contrast, no advantage of GH over pertechnetate could be detected in the study of infarcts or other ischemic lesions. Various hypotheses are discussed to explain the observed differences in behavior between the two tracers.

Adult↗