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Biomedical subjects

F Ferre

Publications and source records attributed to F Ferre.

At least 37 records · Page 2Linked to original sources
PubMed1993

T cell receptor V beta repertoire in HIV-infection individuals: lack of evidence for selective V beta deletion.

The gradual decline of CD4+ T lymphocytes in HIV-infected individuals culminates in the lethal immunosuppression of AIDS. The mechanism of CD4+ T cell loss is currently unknown, but has recently been suggested to occur as a result of an HIV-encoded superantigen which facilitates a selective deletion of T cells expressing specific V beta genes. To verify and extend such observations, peripheral blood leucocytes (PBL) from 15 HIV+ individuals, 10 of which had very low CD4 T cell counts (< 200/mm3), were analysed for T cell receptor (TCR) V beta gene expression. In contrast to a recent study, the results presented here fail to provide evidence that selective loss of V beta-bearing T cells occurs in HIV+ individuals. Furthermore, when PBL from HIV+ individuals were stimulated with Staphylococcal enterotoxin B (SEB), T cells expressing V beta subfamilies known to engage this superantigen were expanded, indicating that such cells were not deleted and were responsive to stimulation by a bacterial superantigen. Collectively, these data suggest that CD4 loss in HIV patients does not occur in a V beta-selective, superantigen-mediated fashion.

Base Sequence↗
PubMed1993

Biochemical characterization and autoradiographic localization of [125I]endothelin-1 binding sites on trophoblast and blood vessels of human placenta.

The presence of endothelin binding sites in the human placenta raises the question of the precise localization of these receptors on well defined placental constituents. In order to find an answer to this problem various approaches were used. Specific binding sites for [125I] endothelin-1 (ET-1) were identified on human term placenta, not only on membranes of smooth muscles stem villi vessels, but also on trophoblastic plasma membranes prepared from trophoblast in culture. Scatchard analysis of binding data revealed a single class of high affinity binding sites with Kd values of 26 +/- 4 pmol/L for stem villi vessels and 126 +/- 4 pmol/L for trophoblast in culture, with maximum binding capacities of 681 +/- 61 and 224 +/- 53 fmol/mg protein, respectively. The anatomical localization of these binding sites was determined by in vitro autoradiography. Autoradiograms obtained from placental sections incubated with [125I]ET-1 indicate that [125I]ET-1 high affinity binding sites exist on placental stem villi vessels and on the trophoblastic layer of the villi. The latter localization was also found on autoradiograms of trophoblast in culture. The human placental syncytiotrophoblast is a polarized epithelium with the microvillous membrane, facing maternal blood space and the basal plasma membrane, facing fetal circulation. [125I]ET-1 high affinity binding sites are present on both membranes but the number of binding sites is higher on the basal plasma membrane. These findings lead to the suggestion that ET-1 may be involved in the regulation of the feto-placental circulation and may subserve specific trophoblastic functions.

Arteries↗
PubMed1993

Cell-mediated immunity to HIV-1 in Walter Reed stages 1-6 individuals: correlation with virus burden.

Cell-mediated immunity (CMI) to human immunodeficiency virus-1 (HIV-1) was assessed in a blinded fashion for a patient group (n = 79) representing Walter Reed (WR) stages 1-6. At the same time, viral load was quantitatively measured by two different methods, specifically, virus isolation and HIV viral DNA copy number as measured by the polymerase chain reaction (PCR). After unblinding it was determined that the ability to generate a lymphoproliferative response to an inactivated gp120-depleted HIV (HIV-ag) and tetanus toxoid diminished with advancing WR staging, with complete anergy to HIV-ag and tetanus at stage 6. As a group, individuals whose peripheral blood mononuclear cells (PBMC) proliferated to HIV-ag were either virus isolation negative or produced low levels of virus as measured by p24 antigen (< 250 pg p24) on day 7. Similarly, HIV DNA copy number in the HIV-ag responders was low (< 200 copies/4 x 10(5) PBMC). In contrast, antigen proliferation to tetanus toxoid did not correlate with virus load. Thus, clinical progression as defined by the WR staging system appears to coincide with a loss of CMI to HIV. More importantly, the low viral load measured in HIV-ag responders suggests a link between viral burden and CMI to HIV which might be exploited in the design of immunotherapies for HIV-infected individuals.

Cell Division↗
PubMed1993

Progesterone and mifepristone modify principally the responses of circular myometrium to oxytocin in preparturient rats: comparison with responses to acetylcholine and to calcium.

We have recently reported that in the pregnant rat myometrium the synthetic OT/AVP V1 antagonist d(CH2)5[Tyr(Me)2]OVT has similar pA2 values against oxytocin (OT) or arginine vasopressin in longitudinal myometrial strips and against arginine vasopressin in circular myometrial strips. However, the antagonist is inactive against OT in circular strips, suggesting that the receptor involved in the action of OT in circular muscle is distinct from the OT receptor in longitudinal muscle. In this study, models of progesterone-blocked and progesterone + mifepristone-induced rat parturition were designed to check whether progesterone modulated OT responsiveness differentially in the two myometrial layers. Responses to OT were measured in organ bath experiments and compared with responses to acetylcholine and to calcium ions (Ca2+) in depolarized myometrial strips. Compared with control animals at day 21 of pregnancy, maximal responses to OT in longitudinally cut strips from progesterone- or progesterone + mifepristone-treated rats were only marginally affected by steroid treatments. In contrast, progesterone almost totally abolished responses to OT in the circular myometrium, whereas mifepristone treatment restored responses to those seen at spontaneous parturition. In both muscle layers, responses to acetylcholine were unaffected by steroid treatments and those to Ca2+ were decreased by progesterone treatment (however, to a lesser extent than those of OT) and were restored by mifepristone. These results suggest the presence of two populations of OT receptors in the myometrium: a constitutive type of receptor predominent in longitudinal muscle and a progesterone-regulated receptor present in circular muscle.

Acetylcholine↗
PubMed1992

Quantitation of HIV viral burden by PCR in HIV seropositive Navy personnel representing Walter Reed stages 1 to 6.

To quantitate the amount of human immunodeficiency virus type 1 (HIV-1) DNA in peripheral blood mononuclear cells (PBMC) of 78 infected individuals, we have developed a polymerase chain reaction (PCR) assay that is both quantitative and sensitive. Quantitation was based on incorporation of a 32P end-labelled primer (SK39) in the PCR reaction and on comparison after electrophoresis with known amounts of HIV DNA. A linear relationship was obtained between the natural logarithms of the radioactive counts detected and the number of HIV-1 DNA copies (10-1000 copies) from the standard DNA. HIV copy numbers from patient samples were then extrapolated from the standard curves. This sensitive and reproducible method was compared with virus isolation which is a semiquantitative evaluation of viral burden. HIV DNA levels correlated with virus isolation, i.e., high viral burden (100-1000 HIV copies) were found in most samples from which virus was isolated after only 7 days in culture; low viral burden (less than 100 HIV copies) was observed in samples from which virus was isolated after 14 to 21 days in culture. These estimates of viral burden were then compared with the clinical stage of the individuals.

DNA, Viral↗
PubMed1991

Alpha-1 adrenergic receptor: binding and phosphoinositide breakdown in human myometrium.

Alpha-1 adrenergic receptors were examined in both inner and outer layers of human pregnant myometrium using radioligand binding of [3H]prazosin. [3H]prazosin bound rapidly and reversibly to a single class of high affinity binding sites in myometrial membrane preparations. Scatchard analysis gave similar values of equilibrium dissociation constants in both myometrial layers. In contrast, more alpha-1 adrenergic receptors were detected in the outer layer than in the inner layer. Antagonist inhibited [3H]prazosin binding with an order of potency of prazosin greater than phentolamine greater than idazoxan. Competition experiments have also revealed that a stable guanine nucleotide decreases the apparent affinity of norepinephrine for myometrial [3H]prazosin binding sites. The functional status of these alpha-1 adrenergic receptors was also assessed by measuring the norepinephrine-induced accumulation of inositol phosphates in myometrial tissue. Norepinephrine produced a concentration-dependent accumulation of inositol phosphates in both myometrial layers. However, norepinephrine-induced increases in inositol 1,4,5-triphosphate were only observed in the outer layer. These results indicate that alpha-1 adrenergic receptors in human myometrium at the end of pregnancy are linked to phosphoinositide hydrolysis and that this response occurs mainly in the outer layer.

Binding, Competitive↗
PubMed1990

Sensitivity of the human myometrial adenylate cyclase to calcium and calmodulin.

The calcium-calmodulin-dependent regulation of adenylate cyclase was studied in membranes from pregnant human myometrium. In the absence or presence of exogenous calmodulin, free calcium concentrations greater than 50 nmol/l inhibited the adenylate cyclase activity. Activation of the enzyme by calmodulin (0.1-1 mumol/l) was calcium-dependent and maximal at 10 nmol/l free calcium. The myometrial adenylate cyclase activity was stimulated by the guanyl nucleotide, Gpp(NH)p. In the presence of the guanyl nucleotide, the activatory effect of the calcium-calmodulin complex disappeared. The activatory effect of exogenous calmodulin was dependent on endogenous calmodulin present in the myometrial membranes. Trifluoroperazine and calmidazolium were able to inhibit the adenylate cyclase activity.

Adenylyl Cyclases↗
PubMed1989

Correlation between selective inhibition of the cyclic nucleotide phosphodiesterases and the contractile activity in human pregnant myometrium near term.

The present study was carried out to determine the ability of various pharmacological agents to selectively inhibit each cytosolic form of phosphodiesterase isolated from the longitudinal layer of human myometria near term. Among the drugs tested, zaprinast specifically inhibits the first form of PDE which hydrolyses both substrates (cAMP and cGMP) and is stimulated by the Ca2+-calmodulin complex. A second form of PDE specific for cAMP hydrolysis and Ca2+-calmodulin insensitive is only present during pregnancy. Rolipram is the most potent and selective inhibitor of this second form. It is also the most efficient compound to inhibit in vitro the spontaneous contractions of near term myometria. The double effect of rolipram suggests an important role of the second form of PDE in the mechanisms of contractility during the pregnancy. In addition rolipram or other derivatives might be of a therapeutic interest in the prevention of prematurity in so far as they are devoid of undesirable maternal and fetal side effects.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1989

Molecular cloning and sequence of cDNA encoding polyoma medium tumor antigen-associated 61-kDa protein.

Polyoma virus medium tumor antigen forms specific complexes with several cellular proteins; among these is a protein of approximately 61 kDa. With antibodies directed against medium tumor antigen, the 61-kDa protein was purified from human 293 cells that were infected with a hybrid adenovirus and overexpressed medium tumor antigen. The purified 61-kDa protein was partially digested with protease V8, and one of the protease V8 fragments was isolated and partially sequenced. The amino acid sequence information was used to design mixed oligonucleotide probes for screening a cDNA library from human placenta. A clone was isolated that hybridized with two separate probes; the clone contained an insert with an open reading frame for 589 amino acids. By in vitro translation of the transcript from this insert, a protein was generated that had the same size and yielded the same pattern of protease V8 fragments as the original 61-kDa protein. Its amino acid sequence reveals 15 repeats, the majority of which are 39 amino acids long. This protein bears no resemblance to proteins in the data bank that was searched.

Amino Acid Sequence↗
PubMed1989

Beta 2-adrenoceptor response in the rat uterus at the end of gestation and after induction of labor with RU 486.

To study the relationship between the progesterone environment and beta-adrenoceptors in the myometrium, rats were treated with the antiprogestin RU 486 (10 mg per rat) at 08:30 h on day 21 of gestation. Under these conditions, more than 60% of animals delivered within 24 h after this treatment, while none of the control animals delivered within the same time period. beta-Adrenoceptors were identified using the radiolabeled antagonist (-)-[125I] iodocyanopindolol. The density (Bmax approximately 33-45 fmol/mg protein) and the affinity (KD approximately 0.105-0.106 nM) were not changed (during the late stages of gestation) in RU 486 treated rats compared with control rats. These results were correlated with the relaxation of longitudinal and circular strips of myometrium placed in high KC1 medium and exposed to beta-adrenoceptor agonists. The adrenoceptors implicated in the relaxation of myometrial strips were mainly of the beta 2-subtype. There was no difference in their affinity between control and RU 486 treated rats. Mean pA2 values were 8.46 for propranolol and 8.27 for ICI 118-551 against salbutamol. Altogether these results indicate in the rat that the blockade of the action of progesterone at its receptor site by RU 486 did not modify either the affinity or the sensitivity of beta 2-adrenoceptors in the myometrium, although it induced parturition.

Albuterol↗
PubMed1989

Disappearance of beta-adrenergic response of human myometrial adenylate cyclase at the end of pregnancy.

The density of beta-adrenergic receptors in both the outer and inner layers of the human myometrium decreases during the last weeks of pregnancy. Although in preterm myometrium (32-35 weeks of pregnancy) beta-adrenergic receptors are positively coupled to adenylate cyclase, we found that isoproterenol, epinephrine, and norepinephrine did not stimulate the enzyme in the inner or outer myometrial layer at term (39-40 weeks of pregnancy). At this stage, the addition of 10(-4) mol/L guanyl-5'-imidodiphosphate increased (from 10(-8) to 10(-4) mol/L) basal adenylate cyclase activity in a dose-dependent manner, indicating that the catalytic component of the enzyme remains linked to the stimulatory guanyl nucleotide binding protein (Gs). Compared to the preterm response, at term the myometrial adenylate cyclase response to 10(-4) mol/L guanyl-5'-imidodiphosphate was decreased, which may reflect a decrease in the amount of functional Gs. Altogether these changes are consistent with reduced Gs coupling to the catalytic component. However, the similarity of the responses of preterm and term myometrium to forskolin excluded the possibility of an alteration of the catalytic component of adenylate cyclase during the last weeks of pregnancy. The fact that a stimulatory effect of isoproterenol on adenylate cyclase was found after islet-activating protein pretreatment indicates that human term myometrium contains a functional inhibitory guanyl nucleotide binding protein which is involved in the modulation of the beta-adrenergic adenylate cyclase response. Our data suggest that modifications in the coupling mechanisms between receptors and the catalytic component are implicated in the loss of beta-adrenergic adenylate cyclase stimulation in the myometrium at the end of pregnancy.

Adenylyl Cyclases↗
PubMed1988

Evolution of tissue levels of steroids: oestradiol-17 beta, oestrone and progesterone in the macaque myometrium during gestation.

In 15 cynomolgus monkeys between days 30-160 of gestation, tissue levels of oestrone (E1), oestradiol 17 beta (E2) and progesterone (P4) were assayed by RIA in the myometrium and the placenta. Myometrial samples were subdivided as follows: inner and outer layers adjacent to the placental area (IMP and OMP) and inner and outer layers from antiplacental areas (IMAP and OMAP). Steroid levels (ng/g wet wt) were in the range of known plasma values (ng/ml) and there was no asymmetric distribution of steroids between the various locations. When the results obtained in all the layers were pooled the gestational profiles indicated a decrease of E1 between days 80-130, whereas at the same time E2 and P4 increased. The ratio P4/E2 was 8 on day 40, 17 on day 80 and 9 on day 160. In the placenta, levels of E2 and P4 were 4 times higher, levels of E1 10 times higher than in the myometrium. Gestational profiles of the three steroids in the placenta increased from day 30 to day 160. Myometrium steroid content therefore does not appear to be a simple reflection of steroid diffusion from the site of production.

Animals↗
PubMed1987

[Hormones and parturition in primates].

In primates, the endocrine signals which correlate with the end of gestation, i.e. account for fetal maturity, and initiate the parturition, i.e. trigger the myometrium contractility, remain unknown. Direct and indirect evidence supports the view that, as with domestic mammals, progesterone (or the estrogen/-progesterone ratio) plays a prominent role in inhibiting the contractility of the pregnant uterus. In the past few years an increasing number of endocrine factors have been identified in the placenta. They may contribute to the control of local or systemic steroid production but their effects are extraordinarily intermingled and it is impossible today to state whether any of them are relevant to the mechanism of parturition. The trophoblast and the myometrium establish close contact in the primate pregnancy. This is evidenced by histological studies and also by the influence of the proximity of the placenta on tissue steroid concentrations and the mechanisms of hormone coupling in the myometrium. Specific types or subtypes of myometrium hormone receptors are now well identified (e.g. to oxytocin, to catecholamines) and this now permits a better understanding of the role of their endogenous agonists in the course of parturition. However, such data are still lacking for other factors (e.g. prostanoids, VIP, relaxin...) involved to varying degrees in this process.

Animals↗
PubMed1986

Transformation of quail embryo fibroblasts by a retrovirus carrying a normal human c-myc gene.

We have constructed avian retroviruses expressing the human c-myc oncogene. These viruses morphologically transformed primary quail embryo fibroblasts upon transfection and infection. Transformed cells produced viruses harboring a spliced c-myc gene and contained high levels of p64-67c-myc protein. One of these infectious viruses, vSX-AHM, was molecularly cloned and the nucleotide sequence of the spliced c-myc insert determined. No mutation was found within the c-myc coding sequence of this transforming clone when compared to the normal genomic progenitor. Thus, we concluded that no mutation within the human c-myc gene is required to induce primary avian embryo fibroblast transformation.

Animals↗