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Biomedical subjects

P Moreau

Publications and source records attributed to P Moreau.

At least 19 recordsLinked to original sources
PubMed1992

Molecular basis for low temperature compartment formation by transitional endoplasmic reticulum of rat liver.

The molecular basis for temperature compartment formation was investigated using a cell-free system from rat liver. The donor was from liver slices prelabeled with [3H]acetate. Unlabeled Golgi apparatus membranes were immobilized on nitrocellulose as the acceptor. When transfer was determined as a function of temperature, a transition in transfer activity was observed at low temperatures (less than or equal to 20 degrees C) similar to that seen in vivo. The decrease in transfer efficiency correlated with a decrease in phosphatidylethanolamine and phosphatidylserine content of the transition vesicles formed. By adding lipid mixtures enriched in these lipids to the vesicles, their ability to fuse with the cis Golgi apparatus was reconstituted. These findings provide evidence for a role for lipids in low temperature compartment formation.

Adenosine Triphosphate↗
PubMed1992

NADH-activated cell-free transfer between Golgi apparatus and plasma membranes of rat liver.

This report concerns development of a cell-free system from rat liver to study transport of membrane constituents from the Golgi apparatus to the plasma membrane. Highly purified Golgi apparatus as donor and a mixture of sheets and vesicles as plasma membrane acceptor fractions were combined to analyze requirements for lipid and protein transport. In the reconstituted system, the Golgi apparatus donor was in suspension. To measure transfer, membrane constituents of the donor membranes were radiolabeled with [3H]acetate (lipids) or [3H]leucine (proteins). The plasma membrane vesicles were used as the acceptor and were unlabeled and immobilized on nitrocellulose for ease of recovery and analysis. The reconstituted cell-free transfer was dependent on temperature, but even at 37 degrees C, the amount of transfer did not increase with added ATP, was not specific for any particular membrane fraction or subfraction nor was it facilitated by cytosol. ATP was without effect both in the presence or absence of a cytosolic fraction capable of the support of cell-free transfer in other systems. In contrast to results with ATP, NADH added to the reconstituted system resulted in an increased amount of transfer. A further increase in transfer was obtained with NADH plus a mixture of ascorbate and dehydroascorbate to generate ascorbate free radical. The transfer of labeled membrane constituents from the Golgi apparatus to the plasma membrane supported by NADH plus ascorbate radical was stimulated by a cytosol fraction enriched in less than 10 kDa components. This was without effect in the absence of NADH/ascorbate radical or with ATP as the energy source. Specific transfer was inhibited by both N-ethylmaleimide and GTP gamma S. The findings point to the possibility of redox activities associated with the trans region of the Golgi apparatus as potentially involved in the transport of membrane vesicles from the Golgi apparatus to the cytoplasmic surface of the plasma membrane.

Animals↗
PubMed1992

Genomic organization and nucleotide sequence of a long mosaic repetitive DNA in the mouse genome.

A long mosaic repetitive sequence (LMRS) was isolated from a mouse liver genome library using a mouse repetitive DNA as a probe. LMRS exhibits the following features: (1) it is almost 15 kb in length; (2) it is partly organized in tandem array and frequently interrupted by other repeated sequences; and (3) it is located predominantly on the A3 band of the mouse X Chromosome (Chr). One fragment of LMRS (B6) shows restriction fragment length polymorphism (RFLP) between different mouse strains, and is thus potentially useful for mapping studies. The nucleotide sequence confirms a mosaic organization of LMRS which includes three repeats in the 5' part, showing similarity with the 5' end of L1Md-A2, and seven long A + T rich segments in the central part of the element. Our findings suggest that this sequence may have arisen from the duplication of an ancestral motif and has expanded by successive waves of amplification and invasion by foreign sequences.

Animals↗
PubMed1992

Crucial role of the third and fourth hypervariable regions of HLA-DPB1 allelic sequences in the mixed lymphocyte reaction.

Since HLA-DP mismatches are known to induce proliferative response in MLR I, we investigated the real impact of the different DP alleles and the possible role of one or several hypervariable regions of the DPB allelic sequences. Accordingly, we performed MLR I between HLA-A, B, DR, DQ, and Dw identical individuals DP oligotyped after DNA amplification. A total of 23 one-DP-mismatched healthy stimulator and responder cells displaying nine different DP specificities were thus evaluated in 52 MLRs I. This allowed us to analyze the impact of amino acid composition of each of the six hypervariable regions independently of the amino acid matching or mismatching in the five others. We show here that DP combinations sharing the same amino acid sequence in the third (C) and fourth (D) hypervariable regions are associated with a low proliferative response in vitro (p less than 0.01). These data imply that a perfect HLA-DP matching may not be requisite in selecting bone marrow donors. Indeed, the choice of donors may rely on determination of these particular mismatched HVRs between the DP alleles involved especially in GvHD direction. This policy including prospective DP oligotyping should be of great interest, especially when MLRs I are false negative or nonevaluable. It will enable a better definition of which DP mismatches are acceptable in BMT.

Alleles↗
PubMed1992

Reduced renal toxicity and improved clinical tolerance of amphotericin B mixed with intralipid compared with conventional amphotericin B in neutropenic patients.

The clinical use of amphotericin B is sometimes limited by nephrotoxicity. In a randomized prospective study, 32 patients treated for haematological malignancies received either amphotericin B in 5% dextrose (group A, 16 patients, 0.7-1 mg/kg/day), or amphotericin B mixed with Intralipid (group B, 16 patients, 0.7-1 mg/kg/day) during prolonged neutropenia. Renal dysfunction occurred in 9/16 patients in group A and 2/16 patients in group B (P < 0.05). Clinical tolerance was improved with a reduction of fever with chills in 12/16 patients in group A compared with 5/16 in group B (P < 0.05). Preparation of amphotericin B with Intralipid reduces nephrotoxicity, improves clinical tolerance, may allow an increase in the daily dose of amphotericin B, and be an alternative to liposomal-amphotericin B infusion.

Adult↗
PubMed1992

Alterations in circulating levels and cardiovascular tissue content of neuropeptide Y-like immunoreactivity during the development of deoxycorticosterone acetate-salt hypertension in the rat.

OBJECTIVE: To investigate the modification of plasma and tissue neuropeptide Y-like immunoreactivity (NPY-li) concentrations, in relation to blood pressure and plasma catecholamine levels, during the development of deoxycorticosterone acetate (DOCA)-salt hypertension. METHODS: Mean arterial pressure (MAP), heart rate, tissue and plasma NPY-li levels, and aortic norepinephrine and epinephrine plasma levels were measured in conscious DOCA-salt hypertensive rats treated for 1, 2 and 3 weeks, and in their respective normotensive controls. RESULTS: Both norepinephrine and NPY-li plasma levels increased significantly in parallel with blood pressure during DOCA-salt treatment, so that MAP was significantly correlated with plasma norepinephrine and NPY-li levels in hypertensive rats. Plasma NPY-li levels were also correlated with norepinephrine levels only in hypertensive rats, but were correlated with epinephrine levels only in normotensive animals. Tissue NPY-li content was lower in the mesenteric artery and heart ventricles after 1-3 weeks of DOCA-salt treatment, but the content in the adrenal gland was not significantly different from that in normotensive rats. CONCLUSIONS: In DOCA-salt hypertensive rats, increased plasma NPY-li levels originate primarily from the sympathetic nerves, since those levels were correlated exclusively with circulating norepinephrine levels and they were associated with a reduction in NPY-li content of the heart and mesenteric artery. It is thus possible that the enhanced release of NPY-li from sympathetic nerves could contribute to the rise in blood pressure and to the maintenance of hypertension in this experimental model.

Animals↗
PubMed1991

Monensin blocks the transfer of very long chain fatty acid containing lipids to the plasma membrane of leek seedlings. Evidence for lipid sorting based on fatty acyl chain length.

Delivery of newly synthesized fatty acids and lipids to the plasma membrane in leek seedlings via the endoplasmic reticulum (ER)-Golgi apparatus pathway is primarily by bulk transport (without sorting). However, pulse-chase experiments revealed kinetics of transport of lipids with VLCFA (very long chain fatty acids having more than 18 carbon atoms) in favor of a preferential transfer of these molecules to the plasma membrane. Use of monensin showed the accumulation of lipids in the Golgi apparatus and a related decrease of the amount of lipids transported to the plasma membrane. Lipid and fatty acid analyses revealed that transport of VLCFA-containing phospholipids was most strongly inhibited by the monensin block. These results taken together with an inability of the plasma membrane to synthesize VLCFA support a role for the Golgi apparatus in VLCFA delivery to the plasma membrane and leads to the hypothesis of a sorting function as well, based on fatty acyl chain length.

Allium↗
PubMed1991

Trafficking of lipids from the endoplasmic reticulum to the Golgi apparatus in a cell-free system from rat liver.

Trafficking and sorting of lipids during transport from the endoplasmic reticulum to the Golgi apparatus was studied using a cell-free system from rat liver. Transitional elements of the endoplasmic reticulum were prepared from liver slices prelabeled with [14C]- or [3H]acetate as the donor fraction. Non-radioactive Golgi apparatus were immobilized on nitrocellulose as the acceptor. When reconstituted, the radiolabeled donor retained a capacity to transfer labeled lipids to the non-radioactive Golgi apparatus acceptor. Transfer exhibited two kinetically different components. One was stimulated by ATP, facilitated by cytosol and inhibited by guanosine 5'-O-(thiotriphosphate) and N-ethylmaleimide. In parallel with protein transport, the ATP-dependent lipid transfer occurred with a temperature transition at about 20 degrees C. The other was not stimulated by ATP, did not require cytosol, was acceptor unspecific, was unaffected by inhibitors and, while temperature dependent, did not exhibit a sharp temperature transition. The ATP-independent transfer was non-vesicular. In contrast, the ATP-dependent transfer was vesicular. Transition vesicles isolated by preparative free-flow electrophoresis, when used as the donor fraction, transferred lipids to Golgi apparatus acceptor with a 5-6-fold greater efficiency than that exhibited by the unfractionated transitional endoplasmic reticulum. Formation of transition vesicles was ATP-dependent. Transferred lipids were chiefly phosphatidylcholine and cholesterol. Membrane triglycerides, major constituents of the transitional endoplasmic reticulum membranes, were both depleted in the transition vesicle-enriched fractions and not transferred to Golgi apparatus suggestive of lipid sorting prior to or during transition vesicle formation. The characteristics of the ATP plus cytosol-dependent transfer were similar to those for protein transfer mediated by transition vesicles. Thus, the 50-70-nm vesicles derived from transitional endoplasmic reticulum appear to function in the trafficking of both newly synthesized proteins and lipids from the endoplasmic reticulum to the Golgi apparatus.

Adenosine Triphosphate↗
PubMed1991

Cell-free transfer of membrane lipids. Evidence for lipid processing.

A latent phospholipase A is concentrated in cis elements of rat liver Golgi apparatus, the presumed sites of fusion of the 50-70-nm transition vesicles formed from endoplasmic reticulum. As a result, conversion of transferred phospholipids to their corresponding lysoforms may provide an index of post transfer lipid processing in a corresponding reconstituted membrane transfer system. To label the phosphatidylcholine of transitional endoplasmic reticulum in vitro, [14C]CDP-choline and endogenous cytidyltransferases were used. In the reconstituted transfer system, the radiolabeled phosphatidylcholine was transferred via transition vesicles to Golgi apparatus immobilized on nitrocellulose strips in a time- and temperature-dependent process. Transfer was promoted by ATP and the ATP-dependent transfer was specific for cis Golgi apparatus elements as acceptor. Trans Golgi apparatus elements were ineffective as acceptors. Median Golgi apparatus elements were intermediate. A portion of the transferred phosphatidylcholine was converted subsequently to lysophosphatidylcholine also in a time- and ATP-dependent manner. The phospholipase A activity of the Golgi apparatus was more than 90% latent (active site located on the lumens of the Golgi apparatus membranes). Therefore, the lipid-containing vesicles derived from endoplasmic reticulum must have combined with cis Golgi apparatus membranes as the basis for Golgi apparatus-dependent phospholipase A processing of endoplasmic reticulum-derived phosphatidylcholine. Since the lipids were processed by phospholipase A in approximately the same proportion as occurs in situ, the findings offer evidence both for the specificity of the ATP-dependent component of cell-free lipid transfer from endoplasmic reticulum to Golgi apparatus and its fidelity to lipid transfer observed in vivo.

Adenosine Triphosphate↗
PubMed1991

Autosomal dominant arthropathy in a French family.

We studied a French family in which 18 adult members had destructive arthropathy and enthesopathic changes. In 16 patients, the diagnosis was verified radiologically, and in the 2 other patients, the clinical history was consistent with familial arthropathy. The disease predominantly affects the wrists, fingers, shoulders, and peripheral entheses, and its onset occurs after age 18. Genetic transmission is autosomal dominant, with 100% penetrance, and is not related to the HLA system. The clinical and radiologic features are strikingly similar in all patients in successive generations and different branches of the genealogic tree, and this suggests monogenic transmission.

Age Factors↗
PubMed1991

Gamma irradiation alters bluetongue virus protein antigen.

Bluetongue virus (BTV) antigen, prepared for a monoclonal antibody (MAb)-based competitive enzyme-linked immunosorbent assay (C-ELISA), was exposed to 1, 2, 3, 4, 5 and 6 Mrad of gamma irradiation. The major group-specific BTV protein (VP7) reactive with the Mab was altered at higher doses of radiation, as revealed by immunoblotting studies. As well, a reduction in immunoreactivity was noted when irradiated antigen was used in the ELISA.

Animals↗
PubMed1990

Computed tomography of metastatic cervical lymph nodes. A clinical, computed tomographic, pathologic correlative study.

A retrospective comparative study of 63 neck dissections was undertaken to evaluate further the accuracy of high-resolution computed tomography (CT) in the detection of nodal metastases, as previous studies have indicated a trend toward the superiority of CT scanning over palpation. The respective values of neck examination, CT scanning, and histopathologic examination were assessed in 51 patients with head and neck cancer who underwent a total of 63 neck dissections. The overall agreement between clinical examination findings and histopathologic findings was 92% vs 81% for CT scanning. A retrospective analysis of the CT findings failed to reveal greater accuracy. We found nodes measuring 10 mm or more with central low density always to be malignant. Because CT scanning seems to offer little advantage over palpation in the nonirradiated neck, it should not be regarded as an essential tool in the staging of nodal disease. After radiation therapy, as neck dissection is only performed because of clinical or radiologic suspicion, CT scanning is of utmost importance.

False Negative Reactions↗
PubMed1990

Influence of HLA-DP mismatches on primary MLR responses in unrelated HLA-A, B, DR, DQ, Dw identical pairs in allogeneic bone marrow transplantation.

The success of bone marrow transplantation relies on class I and class II HLA identity between donor and recipient but until now the impact of DP mismatches on primary mixed lymphocyte reaction (MLR I) responses has not yet been clearly established. HLA-DP typing has been performed by a RFLP method on 10 patients and their 22 selected potential donors (HLA-A, B, DR, DQ, Dw identical according to serological, RFLP and oligotyping methods). HLA-DP-matching was then correlated with MLR I responses obtained (1) in 22 HLA-A, B, DR, DQ, Dw identical donor-recipient pairs (patient series) and (2) in 30 HLA-A, B, DR, DQ, Dw identical donors pairs used as the control series. We showed that MLR I responses involving patients cells were always lower than those involving control cells (p less than 0.02 in case of two DP-mismatches and p less than 0.001 in the case of one DP-mismatch). Moreover, in the control series two or one DP mismatches influenced MLR I responses in 91% and 77% of the cases respectively; however, there was a greater scatter of response values which could be explained by the degree of sequence homology between the DP mismatched alleles. In cases with no DP mismatch, no proliferative response was observed. Overall, these results suggest that the conventional technical conditions of MLR I do not allow detection of mismatches other than the well known HLA specificities.

Bone Marrow Transplantation↗