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M Rouleau

Publications and source records attributed to M Rouleau.

18 recordsLinked to original sources
PubMed1994

Mitogenic CD2 monoclonal antibody pairs predispose peripheral T cells to undergo apoptosis on interaction with a third CD2 monoclonal antibody.

When stimulated for a few days with the mitogenic GT2 + T11(1) CD2 mAb pair and IL-2, resting T cells were induced to proliferate but the introduction into the cultures of a third CD2 mAb resulted in apoptotic cell death of 40 to 60% of the cells. The death signal was active on T cells entered the cell cycle without causing an apparent cell cycle block and without discriminating between the G1 and S phases. Apoptosis was not prevented by cycloheximide or actinomycin D, indicating that the death program was already expressed in preactivated cells awaiting an appropriate signal. A series of Abs, directed at various cell surface molecules, were unable to trigger apoptosis (except CD3 mAb), whereas most of the CD2 mAb tested were active, provided the third CD2 mAb was recognizing an epitope different from GT2 and T11(1). Mere aggregation of CD2 molecules did not seem to be the triggering signal of apoptosis, because cross-linking cell-bound GT2 + T11(1) with an Ab to mouse IgG had no effect, suggesting that a conformational change was imposed on CD2 molecules by the third CD2 mAb. Stimulation performed in the presence of IL-2 predisposed both CD45R0+ and CD45RA+ T cells to apoptosis, whereas stimulation in the presence of IL-4 primed only CD45RA+ T cells to undergo this process. Monocytes and potent co-signals of the CD2 pathway were unable to prevent CD2-induced apoptosis. Thus, successive engagements of the CD2 molecule of mature T cells by two and three CD2 mAbs recognizing distinct epitopes can provide in short term cultures signals for proliferation and apoptosis, depending on the activation state of the cells.

Antibodies, Monoclonal↗
PubMed1994

Purification, properties, and subcellular localization of foxtail mosaic potexvirus 26-kDa protein.

The open reading frame 2 (ORF2) of the potexviral genome encodes a 24- to 26-kDa protein which is part of the "triple gene block," a group of overlapping ORFs also present in the genomes of the carla-, hordei-, and furoviruses. The product of these ORFs is believed to play a role in the cell-to-cell movement of the viruses in host plants. The amino acid sequences of the homologous ORF2 products encoded by these related viruses suggest that they specify NTP binding and possibly helicase activities. We have used an Escherichia coli expression system to produce significant amounts of the 26-kDa protein (p26) encoded by foxtail mosaic potexvirus ORF2. p28 was purified to near homogeneity by conventional purification methods and some of its biochemical properties were determined. We present evidence that p26 is an ATP, CTP, and RNA binding protein with apparent ATPase activity. Western blot analysis of infected plant extracts using a polyclonal antiserum produced against p26 indicates that it is a relatively stable protein maintained at high levels for at least 6 days following its peak level of expression. Moreover, it is found predominantly in the soluble fraction of infected tissues. An immunocytochemical analysis of infected Chenopodium quinoa leaves reveals that p26 is exclusively associated with cytoplasmic inclusions in proximity to but distinct from aggregates of viral particles.

Adenosine Triphosphatases↗
PubMed1993

Apoptosis of activated CD8+/CD57+ T cells is induced by some combinations of anti-CD2 mAb.

Peripheral blood CD8+/CD57+ T cells display poor proliferative responses when stimulated with CD3 or CD2 in vitro, but can be induced to proliferate in the presence of exogenous IL-2. Although GT2+T11(1), a mitogenic anti-CD2 mAb pair, could synergize with IL-2 to induce sustained cell divisions in this population (as did immobilized OKT3), D66+T11(1), another anti-CD2 mAb pair, could only induce a small abortive proliferative response. All these antibodies were in contrast strongly mitogenic for CD8+/CD57- T cells. Assuming that D66+T11(1) were exerting inhibitory effects on CD8+/CD57+ T cells, we indeed found that such antibodies profoundly suppressed the anti-CD3 and IL-2-induced proliferation of those cells, but not that of CD8+/CD57- cells. CD2-mediated growth arrest was correlated with rapid cell death occurring within 2 h, once the cells had been submitted to D66+T11(1), and cells susceptible to the death signal were large cells committed in the cell cycle. D66+T11(1)-treated cells had the well-known ultrastructural form of apoptosis, and the DNA extracted from these cells showed the typical ladder pattern of DNA fragmentation accompanying this process. For apoptosis to occur, two anti-CD2 mAb had to be applied to the cells, one of them being D66, suggesting that the corresponding anti-CD2 mAb pairs were imposing on the CD2 molecule a particular conformational change appropriate to transduce a death signal. Notably, CD8+/CD57- T cells were largely resistant to apoptosis in the conditions just described. When exposed to anti-CD3 and IL-2 in primary and secondary cultures, CD8+/CD57+ T cells retained high viability, whereas in contrast, when exposed to D66+T11(1), important cell loss occurred, concomitant with apoptosis, illustrating the specificity of the CD2-derived death signal. Our results suggest that the expansion of CD8+/CD57+ T cells is critically dependent on the CD2 pathway which, according to the conformational change of the CD2 molecule and the activation state of the cells, will direct them either towards proliferation or towards cell death.

Antibodies, Monoclonal↗
PubMed1991

The entire nucleotide sequence of foxtail mosaic virus RNA.

The nucleotide sequence of the RNA genome of foxtail mosaic virus (FMV), a member of the potexvirus family, is 6151 nucleotides long, exclusive of a poly(A) tail. The RNA contains five principal open reading frames (ORFs), designated from the 5' terminus as encoding proteins with Mr values of 152.3K (ORF1), 26.4K (ORF2) which overlaps an 11.3K (ORF3) product, 5.8K (ORF4) which overlaps a 28.8K readthrough protein (ORF5A) which leads into the coat protein cistron of 23.7K (ORF5). The sizes and composition of the proteins encoded by the ORFs are generally similar to those found in other potexviruses; the least similar is the coat protein which nonetheless retains apparently critical consensus regions. The 5' terminus of the previously reported 0.9 kb subgenomic (sg) RNA was determined by S1 nuclease mapping and shown to begin with the sequence GAAGA, 43 nucleotides upstream from the first nucleotide of the coat protein initiation codon. The positions of the 5' end of this sgRNA and of that deduced from the nucleotide sequence for a 1.9 kb sgRNA are entirely consistent with the previously published sizes of these sgRNAs.

Amino Acid Sequence↗
PubMed1990

Induction of cytolytic function in resting peripheral blood CD8+/Leu-7+ T cells through IL2/p 75 IL2-receptor interaction: a study in the allogeneic human bone marrow transplantation model.

CD8+/Leu-7+ T cells which circulate in increased proportions in the blood of long-term surviving BMT patients are for the most part high-density resting lymphocytes lacking IL2R-alpha (p55) expression. We show that they can be induced by IL2 to manifest cytolytic function after 24-48 hr stimulation by using rather high concentrations of IL2 (at least 50 U/ml). This function was much more readily induced in high-density CD8+/Leu-7+ T cells than in high-density CD8+/Leu-7+ T cells and occurred in the presence of minimal cell proliferation. Other cytokines involved in primary CTL differentiation (IFN-gamma, IL4 and IL6) were without effect suggesting that CD8+/Leu-7+ T cells are, in the BMT model, in vivo preactivated CTL ready to differentiate into cytolytic effectors under the sole IL2 stimulus. TU27 Mab directed at IL2R-beta (p75) subunit almost completely prevented IL2-induced cytolytic function of CD8+ T cells while 33B3.1 Mab directed at IL2R-alpha (p55) subunit was ineffective, suggesting that the signal for this function has its origin in IL2R-beta chains constitutively expressed by these cells.

Antibodies, Monoclonal↗
PubMed1990

Ductal heterogeneity of cytokeratins, gene expression, and cell death in the rat ventral prostate.

The rat ventral prostate is a complex gland composed of numerous ducts. The epithelial cells that line the lumen of the ducts are surrounded by stromal cells. The epithelial cells display a characteristic morphology that is dependent on their anatomical location within the ducts; the cells that line the lumen in the region of the ducts close to the urethra (the proximal region) are cuboidal, while those in the distal regions of the ducts are tall columnar cells. We have examined the regional expression of two genes that are expressed in the prostate: prostate steroid-binding protein (PSBP; a marker for androgen-dependent protein synthesis) and TRPM-2 (a marker for programmed cell death). We have demonstrated that the expression of PSBP, in the presence of androgens, and TRPM-2, in the absence of androgens, is restricted to the luminal epithelial cells in the distal regions of the prostatic ducts. Neither of the genes is expressed in the proximal regions of the ducts. In view of the probable effects of the epithelial-stromal interactions in the gland we have also characterized the cytokeratin composition of the epithelial cells lining the prostatic ducts. We have established that the basal epithelial cells of the prostate are primarily localized in the proximal region of the ducts. We propose that these cells may attenuate the influence of the stromal cells on the luminal epithelium and exert a negative influence on the cytodifferentiation of the secretory epithelial cells. The results also suggest that PSBP, which has been considered to be an androgen-dependent gene may, in fact, be a sequence that is constitutively expressed in the luminal cells that die in the absence of androgens. This has significant implications on the mechanism of androgen action in the rat ventral prostate.

Androgen-Binding Protein↗
PubMed1981

Facial nerve sutures: epineural vs. perineural sutures.

The orbicularis oculi branch of the facial nerve was transected in two groups of 15 cats. Following section of the nerve, a specimen was removed for histological studies; then, using microscopic techniques the epineurium was sutured (nylon 10:0) in the first group, and the perineurium in the second. They were then followed for 100 days. Results rely on clinical (complete closure of the eye), electrophysiological (summation potentials), and histological (fiber count) evaluations. Judging from the relative density and diameters of the fibers, epineural sutures result in better regeneration than perineural sutures. With the tremendous importance of the absence of tension on the suture line in mind, it seems that the technique of choice for monofascicular nerves, as in the pyramidal and tympanic segments of the facial nerve, is epineural suture. Despite the slight advantage of epineural suture over perineural suture as evidenced by histological evaluation, there was no clinical difference. The distal fascicular distribution of facial nerve fibers and their spatial distribution make perineural (fascicular) sutures the method of choice when anastomosis becomes necessary in the vertical portion and in the portion distal to the stylomastoid foramen.

Animals↗
PubMed1981

Effects of dilution rates, animal species and instruments on the spectrophotometric determination of sperm counts.

Using semen from bull, boar and stallion as well as different spectrophotometers, we established the calibration curves relating the optical density of a sperm sample to the sperm count obtained on the hemacytometer. The results show that, for a given spectrophotometer, the calibration curve is not characteristic of the animal species we studied. The differences in size of the spermatozoa are probably too small to account for the anticipated specificity of the calibration curve. Furthermore, the fact that different dilution rates must be used, because of the vastly different concentrations of spermatozoa which is characteristic of those species, has no effect on the calibration curves since the dilution rate is shown to be artefactual. On the other hand, for a given semen, the calibration curve varies depending upon the spectrophotometry used. However, if two instruments have the same characteristic in terms of spectral bandwidth, the calibration curves are not statistically different.

Animals↗
PubMed1980

Facial nerve reconstruction.

A retrospective study on 21 patients who had a reconstruction of their facial nerve was undertaken by means of a new photographic method of evaluation. The average of recuperation results was 62.38 per cent. Eighty-five per cent of the patients achieved a good or excellent evaluation. The only individual parameter that showed some influence on the outcome of the surgery was the length of the graft. Compared with a short graft (smaller than or equal to 1 cm), the long graft (larger than or equal to 1 cm) is associated with better results. Good and excellent results appeared available for patients whose pre-operative palsy had lasted from 18 to 36 months.

Adolescent↗
PubMed1978

Arrest of synthesis of specific proteins at the onset of mammary tumor regression.

MTW9 mammary carcinoma regressing after removal of mammotropin stimulation was used as a model to test the hypothesis that the augmented activity of lysosomal enzymes observed during regression may be triggered by a modification of the protein composition of the cytoplasm. In support of the hypothesis, we observed that: (a) the pattern of leucine incorporation into cytosol proteins differs between growing and regressing tumors; (b) the difference is localized in three bands of the electrophoretic pattern; and (c) the change in pattern appears within 6 hr after hormone removal, about 4 hr after prolactin levels in blood were below the concentration needed by MTW9 to grow. These observations are in line with our previous finding of an increased susceptibility of cytosol proteins to proteolytic digesion during MTW9 regression.

Adenocarcinoma↗
PubMed1977

[Comparison between two current methods of surgical treatment for otosclerosis].

Statistical comparison is established between two methods of stapedectomy, the first one being the "Teflon-interposition", the second being Schuknecht's method (gelfoam and preformed wire). There is statistical evidence that the Teflon-interposition method is better. The results are also compared with those of other workers.

Adult↗
PubMed1977

Increased susceptibility of cytosol proteins to proteolytic digestion during regression of a hormone-dependent mammary tumor.

Regression of MTW9 mammary carcinoma, which consistently follows withdrawal of mammotropic hormones, was characterized by a rapid decrease of thymidine incorporation into DNA but only a slight reduction or uridine incorporation into RNA and amino acid incorporation into proteins. Within 24 hr of hormone withdrawal, cytosol proteins of MTW9 became more easily degraded by trypsin, alpha-chymotrypsin, or subtilisin BPN'. Labilization of cytosol proteins occurred much earlier than any change in the level of protein synthesis or lysosomal enzyme activity. The data showing increased susceptibility to proteolysis could not be explained either by the presence of endogenous proteases, by the destruction of the exogenous proteases used in the assay, or by the existence of protease inhibitors. Nor were any differences detected either in the distribution of radioactive precursor among the cytosol proteins from growing or regressing tumors or in the electrophoretic pattern of the same proteins. Preincubation of the cytosol proteins with dithiothreitol or with prolactin, 17 beta-estradiol, progesterone, and hydrocortisone did not modify the susceptibility to proteolysis. However, after heat denaturation, cytosol proteins of regressing and growing tumors became equally susceptible to proteolysis. It is suggested that regression of MTW9 mammary carcinoma occurs not only because cell reproduction is arrested, but also because susceptibility of cytosol proteins to proteolysis is increased.

Animals↗
PubMed1975

Purification and characterization of a trypsin inhibitor from Solanum tuberosum.

A trypsin inhibitor isolated from a potato acetone powder has been purified by affinity chromatography. This protein inhibits trypsin mole per mole. To a lesser extent it combines also with chymotrypsin and elastase. For trypsin, K1 = 8 X 10(-7) M. The inhibitor has a single polypeptide chain of 207 amino acid residues. It contains no sugar or free sulfhydryl groups. Its extinction coefficient E2801% = 10.3 and its isoelectric point is 6.9. Its molecular weight is of the order of 21 000-22000, as determined by sedimentation equilbrium, by inhibition experiment or from its amino acid composition. These same techniques, taken together with the single band observed at different pH on polyacrylamide gel electrophoresis, indicate that the protein purified is monodisperse. However, the finding of two N-terminal amino acid residues, leucine and aspartic acid, and the different stoichometry observed during the interaction of the inhibitor, either with trypsin or with chymotrypsin and elastase, raises the possibility that our preparation is contaminated by a polyvalent inhibitor not detectable by physiochemical methods.

Amino Acids↗
PubMedDate not supplied

IL-2-R beta expression and function within resting CD8+ T cells preferentially segregate with the CD45R0+ subset.

Human peripheral blood CD8+ T cells constitutively express a low level of IL-2-R beta chains which were shown in this study to be preferentially carried by the CD45R0+ subset. Such receptors can transduce signals for in vitro IL-2-induced cytolytic function and for the initiation of soluble anti-CD3 and IL-2-induced cell proliferation. Using these stimulation models, a comparison was made between the responsiveness of resting, small CD45R0+ and CD45RA+ subpopulations of CD8+ T cells, both of them being isolated by negative selection and rigorously depleted of monocytes and of IL-2-inducible non-MHC-restricted CTL. Strong proliferation was induced in CD8+/CD45R0+ cells in response to IL-2 and soluble anti-CD3 (each of these stimuli being by itself ineffective), while in contrast, CD8+/CD45RA+ cells manifested, in this system, little reactivity. Accordingly, no conversion to the CD45R0 phenotype occurred in single stained CD45RA+ T cells following their incubation with the stimuli. A similar restriction of reactivity to CD8+/CD45R0+ T cells was observed with respect to IL-2-induced targetable T cell cytotoxicity. The CTL activity induced by IL-2 alone occurred without cell division. In contrast, the additional increase in CTL activity occurring upon the synergistic actions of anti-CD3 mAb and IL-2 coincided with intense cell proliferation, with no generation of LAK activity. The inhibition exerted by anti-IL-2-R beta mAb in the cytolytic and the proliferative activities induced by these stimuli in resting CD8+/CD45R0+ T cells emphasizes the importance of constitutive IL-2-R beta chains in the biology of these cells.

Antigens, CD↗