PubMed Health⌕ Search

Biomedical subjects

P Grellier

Publications and source records attributed to P Grellier.

At least 73 records · Page 4Linked to original sources
PubMed1994

Actin in the acrosome of the spermatozoa of the crab, Cancer pagurus L. (Decapoda, Crustacea).

The cytoskeletal protein actin was identified in the mature spermatozoon of the European edible crab, Cancer pagurus Linnaeus, by indirect immunofluorescence with monoclonal and polyclonal anti-actin antibodies, fluorescent phalloidin, and DNAase I. The actin was localized in two distinct concentric rings within the acrosome vesicle of the spermatozoon and appeared to correlate with the internal zonation of the vesicle. Modifications of the fluorescent pattern for actin were observed in sperm cells which were undergoing changes associated with the acrosome reaction. In these cases, fluorescent staining was observed in the nucleocytoplasm immediately subjacent to the perforatorial column and sometimes in the perforatorial column within the acrosome vesicle. Equally intense fluorescence was observed in an apical perforatorial projection. SDS-PAGE of C. pagurus sperm confirmed the presence of actin in the cells. A single band of actin (approximately 43 kDa) comigrated with rabbit muscle actin when immunoblotted onto nitrocellulose with mouse monoclonal anti-actin. The actin-associated cytoskeletal proteins alpha-actinin, tropomyosin, and spectrin were also identified within the spermatozoon of C. pagurus using specific polyclonal antibodies, but their presence was not confirmed by SDS-PAGE and immunoblotting.

Acrosome↗
PubMed1994

A large multigene family expressed during the erythrocytic schizogony of Plasmodium falciparum.

We report the identification of a large multigene family of Plasmodium falciparum using a clone isolated with a polyclonal antiserum raised to a Babesia divergens merozoite protein. The recombinant antigen reacted with human sera collected from individuals exposed to malaria. The deduced protein sequence contains a motif homologous to the consensus sequence of merozoite rhoptry proteins encoded by multigene families in several Babesia species. Antibodies raised to the recombinant protein reacted with a 60-kDa merozoite protein both on B. divergens and on P. falciparum immunoblots. The insert hybridized to a large number of fragments on P. falciparum Southern blots and to most chromosomes of the parasite. Specifically, approx. 3-kb RNAs were detected in 4-16-nucleus schizonts. Ten distinct cDNAs were isolated that differed in the size, position and number of restriction sites in the region homologous to the original genomic clone. With about 140 copies per haploid genome, this is the first large multigene family described in malaria parasites. The existence of a multigene family encoding proteins present in the invasive stage of malaria parasites suggests an important role in invasion and denotes a significant potential for generating diversity.

Amino Acid Sequence↗
PubMed1994

Characterization of a new 60 kDa apical protein of Plasmodium falciparum merozoite expressed in late schizogony.

Immunological cross-reactivity studies between the Apicomplexa Babesia divergens and Plasmodium falciparum allowed us to identify a P falciparum 60 kDa protein (Pf60) using an antiserum directed against a B divergens 37 kDa culture-derived exoantigen. In immunofluorescence assays (IFA), Pf60 appears as a doublet of fluorescent spots associated to the apical pole of merozoites. The doublet co-locates with two rhoptry components: the protein RAP-1 and the 140/130/110 (105) kDa rhoptry protein complex suggesting the rhoptry location of Pf60. The biosynthesis of Pf60, established by labeling experiments with [35S]methionine on synchronized cultures, and by immunofluorescence detection, occurred during late schizogony. The physico-chemical properties of Pf60, the absence of identified precursor forms and the absence of co-precipitation with other proteins indicated a new class of rhoptry protein. Pf60 was detected in all the different geographic P falciparum strains so far tested, with a slight variability in molecular mass ranging from 58 to 60 kDa. During the invasion process of erythrocytes by merozoites, the IFA showed the presence of the Pf60 in the apex of free merozoites, but not in invading merozoite, as well as in new ring-infected erythrocytes. Furthermore, immunoprecipitation assays indicated the presence of Pf60 in the culture medium, and its absence in new ring-infected erythrocytes. All together these results suggest a possible involvement of the Pf60 protein in the invasion process.

Animals↗
PubMed1994

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors lovastatin and simvastatin inhibit in vitro development of Plasmodium falciparum and Babesia divergens in human erythrocytes.

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors lovastatin and simvastatin inhibit the in vitro intraerythrocytic development of Plasmodium falciparum and Babesia divergens, with concentrations inhibiting parasite growth by 50% in the ranges of 10 to 20 and 5 to 10 micrograms.ml-1, respectively. For P. falciparum, the 50% inhibitory concentrations were in the same range whatever the chloroquine susceptibility of the strains tested (strain F32/Tanzania [chloroquine susceptible] or FcB.1/Columbia [resistant]). The stage-dependent susceptibility of P. falciparum to simvastatin was studied by subjecting synchronized cultures to 6-h pulses of drug throughout the 48-h erythrocytic life cycle. The most important inhibitory effects were observed between the 12th and 30th hours of the cycle, corresponding to the trophozoite stage. This period precedes the S phase and the nuclear divisions. Parasites in the newly formed ring stage (time zero to the 6th hour of the cycle) and the schizont stage (30th to 48th hour of the cycle) were weakly or not susceptible to simvastatin pulses.

Animals↗
PubMed1994

Plasmodium falciparum proteinases: cloning of the putative gene coding for the merozoite proteinase for erythrocyte invasion (MPEI) and determination of hydrolysis sites of spectrin by Pf37 proteinase.

Numerous proteinase activities have been shown to be essential for the survival of Plasmodium falciparum. One approach to antimalarial chemotherapy, would be to block specifically one or several of these activities, by using compounds structurally analogous to the substrates of these proteinases. Such a strategy requires a detailed knowledge of the active site of the proteinase, in order to identify the best substrate for the proteinase. Aiming at developing such a strategy, two proteinases previously identified in our laboratory, were chosen for further characterization of their molecular structure and properties: the merozoite proteinase for erythrocytic invasion (MPEI), involved in the erythrocyte invasion by the merozoites, and the Pf37 proteinase, which hydrolyses human spectrin in vitro.

Animals↗
PubMed1994

[Single cerebral metastasis of bronchopulmonary cancers].

The most frequent brain metastasis originates from a lung cancer. About half of them are unique. We report a series of 36 patients with lung cancer, operated for a single brain lesion. The mean age was 57.6 years, most (83.3%) were male. Most of the metastases originated from a primary adenocarcinoma (52.8%), in 10 patients (27.8%) from an epidermoid carcinoma, in 4 patients (11.1%) from a small cell carcinoma and in 3 patients from a mixed lesion. The metastatic lesion was detected before the primary lesion in 20 cases (55.5%). The mean post-operative survival was 9.6 months. 36% were alive one year after surgical treatment. We evaluated our clinical findings, histopathological studies and the type of surgical and medical post-operative management, at the cerebral and pulmonary level, in order to make a possible prognosis. In our series we found that only post-operative clinical status (Karnofsky score) and the post-operative neurological grading (Order classification) were significant factors (p < 0.001) to determine survival time.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1993

[Intracranial cavernoma. 30 cases].

During the last few years, as a result of improved neurodiagnostic procedure there has been an increase in the number of intracranial cavernous angioma. We present 30 cases totalling 32 cavernous angiomas. Twenty-one received a successful surgical treatment. Twenty-four angiomas were supratentorial (75 percent) and 8 subtentorial (25 percent). Cavernous angiomas are congenital vascular malformations, usually of small size, with multiple vascular cavities surrounded by fibrous walls. They are often found in young adults (mean age 35 years in our series), most frequently located in the supratentorial white matter. The presenting symptoms were epilepsy, haemorrhage and an expanding mass syndrome. In this series, 16 patients had epilepsy (53 percent), 7 had haemorrhage (23.5 percent) and 7 had a mass syndrome (23.5 percent). The diagnosis of this lesion, usually obtained with angiography, has been dramatically improved by CT scan and, particularly, MRI. The natural history of cavernous angiomas is still poorly understood: the major complication is haemorrhage. Total surgical excision is the treatment of choice: it avoids a possible haemorrhage and is effective in relieving epileptic seizures. The indication for surgery depends on the clinical symptom and the location of the lesion. The post-operative morbidity in our 21 operated cases was fairly low due to minor sequelae. In only 2 of the 16 patients who had epilepsy the clinical seizures persisted after surgery, but they were less frequent. The literature is reviewed.

Adolescent↗
PubMed1993

Plasmodium falciparum proteinases and red blood cell invasion.

Malarial proteinases of the erythrocytic life-cycle are used to design new inhibitors capable of blocking the parasite's development. The Merozoite Proteinase for Erythrocytic Invasion (MPEI) of Plasmodium falciparum, a neutral proteinase, and the acidic Pf37 proteinase acting on spectrin as substrate, are good candidates for this kind of strategy.

Amino Acid Sequence↗
PubMed1992

Purification and characterization of a new 120 kDa alkaline proteinase of Trypanosoma cruzi.

A new alkaline proteinase activity was identified in cell-free extracts of Trypanosoma cruzi epimastigotes on the basis of its ability to hydrolyze the fluorogenic substrate N-Z-Gly-Gly-Arg-AMC. The optimal activity was at pH 8.0. After a three step-chromatography procedure using two anionic columns (DEAE-Sepharose and Mono Q) and a chromatofocusing column (Mono P), the proteolytic activity was associated with a single 120 kDa protein and was called Tc 120 proteinase. The molecular mass of the proteinase was confirmed by direct visualization of the proteolytic activity using a fluorometric assay on SDS-PAGE. The Tc 120 proteinase which also cleaves N-Z-Arg-AMC, N-Z-Phe-Arg-AMC and N-glutaryl-Gly-Arg-AMC substrates, is a cysteine-type proteinase with an unusual low sensitivity to E-64.

Amino Acid Sequence↗
PubMed1992

[Intracranial dural arteriovenous fistula with spinal venous drainage].

Two cases of intracranial dural arteriovenous fistulae draining into the medullary veins are reported. One patient was a 68-year old man who experienced brief and repeated episodes of paraplegia, followed by a permanent spinal cord syndrome. The other patient was a 74-year-old woman who rapidly developed a syndrome of the medulla and spinal cord. In both cases spinal cord angiography failed to show vascular malformations, but myelography revealed venous imprints and magnetic resonance imaging of the cervical spinal cord disclosed a pre-medullary signal. Cerebral angiography showed an intracranial arteriovenous fistula fed by the external carotid artery and draining into the veins of the posterior fossa and the spinal venous network. Complete occlusion of the fistula was achieved by embolization with microparticles. Intracranial dural arteriovenous fistulae draining into the medullary veins are rare: to our knowledge, only 4 cases have been reported. Such lesions must be considered whenever a spinal cord syndrome has no detectable cause.

Aged↗
PubMed1991

Peptide derivatives specific for a Plasmodium falciparum proteinase inhibit the human erythrocyte invasion by merozoites.

A specific proteinase of P. falciparum merozoites has been detected by using hydrosoluble fluorogenic peptidic substrates synthesized by classical peptide chemistry; their N-terminal end was acylated by a gluconoyl group that protects them from aminopeptidase degradation and increases their hydrosolubility, and their carboxylic end was substituted by a 3-amino-9-ethylcarbazole group. The sequence Val-Leu-Gly-Lys was found to be the most specific substrate. On this basis, reversible peptidic inhibitors were synthesized by substituting the C-terminal lysyl residue, at the proteolytic site, by different alkylamines and amino alcohols. The activity of these compounds, studied on the P. falciparum proteinase and in in vitro cultures, strongly suggests a specific effect of this peptidic sequence on the reinvasion process. The peptidic inhibitors do not impair the release of merozoites from schizonts, but selectively inhibit the invasion step leading to the formation of rings. Although the natural target of this enzyme is not yet known, these specific peptide inhibitors could lead to a new antimalarial approach.

Amino Acid Sequence↗
PubMed1991

Lipid traffic between high density lipoproteins and Plasmodium falciparum-infected red blood cells.

Several intraerythrocytic growth cycles of Plasmodium falciparum could be achieved in vitro using a serum free medium supplemented only with a human high density lipoprotein (HDL) fraction (d = 1.063-1.210). The parasitemia obtained was similar to that in standard culture medium containing human serum. The parasite development was incomplete with the low density lipoprotein (LDL) fraction and did not occur with the VLDL fraction. The lipid traffic from HDL to the infected erythrocytes was demonstrated by pulse labeling experiments using HDL loaded with either fluorescent NBD-phosphatidylcholine (NBD-PC) or radioactive [3H]palmitoyl-PC. At 37 degrees C, the lipid probes rapidly accumulated in the infected cells. After incubation in HDL medium containing labeled PC, a subsequent incubation in medium with either an excess of native HDL or 20% human serum induced the disappearance of the label from the erythrocyte plasma membrane but not from the intraerythrocytic parasite. Internalization of lipids did not occur at 4 degrees C. The mechanism involved a unidirectional flux of lipids but no endocytosis. The absence of labeling of P. falciparum, with HDL previously [125I]iodinated on their apolipoproteins or with antibodies against the apolipoproteins AI and AII by immunofluorescence and immunoblotting, confirmed that no endocytosis of the HDL was involved. A possible pathway of lipid transport could be a membrane flux since fluorescence videomicroscopy showed numerous organelles labeled with NBD-PC moving between the erythrocyte and the parasitophorous membranes. TLC analysis showed that a partial conversion of the PC to phosphatidylethanolamine was observed in P. falciparum-infected red cells after pulse with [3H]palmitoyl-PC-HDL. The intensity of the lipid traffic was stage dependent with a maximum at the trophozoite and young schizont stages (38th h of the erythrocyte life cycle). We conclude that the HDL fraction appears to be a major lipid source for Plasmodium growth.

Animals↗
PubMed1991

Characterization of a monoclonal antibody to human proacrosin and its use in acrosomal status evaluation.

Among the monoclonal antibodies (MAb) selected after immunization of mice with a detergent-insoluble fraction from human spermatozoa, MAb 4D4 was found to stain in immunofluorescence the principal part of the acrosome of human spermatozoa. Acrosome reaction induced decreased and spotty 4D4 immunofluorescence staining. Immunoelectron microscopy before or after embedding revealed that the epitope defined by MAb 4D4 was sequestered in the anterior acrosomal matrix and, after the acrosome reaction, remained partly bound on matrix elements attached to the inner acrosomal membrane. Western blot analysis of sperm extracts showed that the epitope defined by MAb 4D4 was located on a 55 KD polypeptide in whole cells and on 55 and 50 KD polypeptides in non-ionic detergent fractions. Human proacrosin-enriched fraction obtained by FPLC purification exhibited several proteolytic activities against gelatin in gel enzymography: a 50 KD major band and two minor bands in the 20-30 KD area; the 50 KD polypeptide reacted with MAb 4D4 in Western blots. Furthermore, the 4D4-immunoprecipitated polypeptide from sperm extract showed that the 50 KD band exhibited proteolytic activity with an optimal pH at 8.0 that was strongly inhibited by soybean trypsin inhibitor and ZnCl2. MAb 4D4 also reacted with the acrosome of the monkey Macaca fascicularis but not with the acrosome of any of the other non-primate mammalian species examined so far. Various shape defects of the acrosomal principal region were revealed by 4D4 labeling of spermatozoa with head anomalies from infertile patients. MAb 4D4 also recognized proacrosin in paraffin-embedded human testis sections. These data make the monoclonal antiproacrosin antibody 4D4 an efficient tool for evaluation of the acrosomal status of human spermatozoa and spermatids.

Acrosin↗
PubMed1991

Isolation and characterization of a soluble antigen complex of Plasmodium falciparum with pyrogenic properties.

A soluble antigen complex, previously designated antigen no. 7 (Ag7) on the basis of the pattern obtained by crossed immunoelectrophoresis of culture supernatants of P. falciparum, was isolated by affinity chromatography. It was shown to be synthesized at the schizont stage of the parasite growth cycle and to be located on the surface of the schizonts. Antibodies to Ag7 did not inhibit the growth of the parasite in vitro. Ag7 is recognized by immune human sera from many parts of the world and it stimulated the production of specific antibody in mice when incorporated into immune-stimulating complex (ISCOM) structures. It also specifically stimulated in vitro proliferation of lymphocytes from clinically immune adults. That it induced the secretion of interleukin 1 by human monocytes and was pyrogenic in rabbits was of particular interest. Thus Ag7 has endotoxin-like properties which make it a possible candidate for an antitoxic malaria vaccine.

Animals↗
PubMed1991

Identification and localization of a soluble antigen, Ag2, of 136 kDa from Plasmodium falciparum in vitro cultures.

The soluble antigens, antigen 2 (Ag2) and antigen 6 (Ag6), were copurified from supernatants of P. falciparum in vitro cultures by affinity chromatography and Fast Protein Liquid Chromatography. Rabbit antibodies to Ag2 were raised and characterized by crossed immunoelectrophoresis. Ag2 appeared as a duplet with molecular masses of 136 and 120 kDa when tested by immunoblotting. Immunoprecipitation experiments on Triton X-100 extracted antigens from synchronized cultures showed that the antigen was synthesized in the schizont stage. Ag2 was located near the surface of schizonts in the parasitophorous vacuole and in clefts in the infected erythrocyte cytoplasma as shown by immunogold electron microscopy.

Adult↗