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Biomedical subjects

A Garcia

Publications and source records attributed to A Garcia.

At least 199 records · Page 11Linked to original sources
PubMed1995

Longitudinal survey of Loa loa filariasis in southern Cameroon: long-term stability and factors influencing individual microfilarial status.

A longitudinal, one-year survey of Loa loa infection was carried out in an endemic area of southern Cameroon. Parasitologic samplings (calibrated thick blood smears) were performed every two months to study the evolution of loiasis infection at both the population and the individual level. The mean number of measurements by subject was 3.8 (range 1-6). At the population level, prevalence of infection and microfilarial load were found to be very stable over time. This observation is consistent with the existence of an important reserve of parasitic material available for vectors and the maintenance of high levels of transmission. At the individual level, both the microfilarial status (microfilaremic/nonmicrofilaremic) and the level of parasitemia showed a remarkable stability over time. Age was the relevant factor that influenced the individual microfilarial status in the whole population. When only microfilaremic individuals were taken into account, age did not influence the level of microfilaremia, suggesting that loiasis could be considered as a noncumulative disease. The stability of individual microfilarial status and the pattern of infection variations observed with age support the view that genetic factors might be involved in host defense mechanisms against loiasis infection.

Adolescent↗
PubMed1995

Diagnostic value of detecting specific IgA and IgM with recombinant Trypanosoma cruzi antigens in congenital Chagas' disease.

The present study compares the early diagnosis of congenital Chagas' disease with a DOT assay using recombinant antigens with immunofluorescence antibody testing (IFAT) and an enzyme-linked immunosorbent assay (ELISA). The studies were performed using cord blood and sera of 12 infected newborns (group I) and 12 uninfected ones born to Trypanosoma cruzi-infected mothers (group II). Conventional IFAT and ELISA showed positive results for IgG at high titers, in infants and mothers of both groups; IgA antibodies were detected by ELISA in four of the infected infants and IgM was detected in two of them. All sera of the uninfected infants were negative for IgA and IgM in the ELISA. Application of a DOT assay using eight recombinant T. cruzi antigens allowed detection of specific IgA in the cord blood of six of the infected cases and IgM in eight of them. Repetition of these serologic tests in samples obtained during a monthly follow-up gave positive results for IgA in two of the initially negative infants of group I and for IgM in four of them. This means that diagnosis of congenital T. cruzi infection was confirmed, through demonstration of specific IgM, in all infected infants, and of IgA in eight of them. The importance of late detection of IgM in siblings born of infected mothers is discussed. The detection of IgM and IgA in sera obtained after birth is believed to be due to a congenital transmission of the parasite that occurred late in pregnancy. No IgA or IgM antibodies could be detected by the DOT assay in the sera of the negative controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

In vitro studies of lymph node analysis.

Endosonography has become a widely accepted diagnostic procedure in the staging of gastrointestinal tumors over the past 10 years. The question of whether endosonography is equally as effective in the diagnosis of regional lymph node metastases has not been conclusively answered. This article presents a brief review of in vitro studies of lymph node analysis in the upper and lower gastrointestinal tract.

Computers↗
PubMed1995

[Role of genetic epidemiology in the study of infectious diseases. The example of malaria].

Genetic epidemiology is a new tool for the study of malaria, with interesting incidence in the comprehension of host/parasite interrelations. The existence of a co-dominant major gene, with a mendelian transmission, controlling the levels of parasitemia has been found out. This allele has a frequency of 24% which means that about 6% of the population is predisposed to high parasitemias. These studies show the interest to integrate the existence of a genetical variability in the development and the evaluation of malaria control programmes. They are offering new perspectives in therapeutics and in the elaboration of vaccinal strategies.

Animals↗
PubMed1995

HIV genome transcription induced by polyoma virus middle T antigen through both enhancer- and promoter-dependent LTR activation.

In order to understand the regulation of HIV genome transcription induced by cell stimulation through transmembrane receptors, we have transfected cells with polyoma middle T antigen (PyMT) expression vectors, thus mimicking activated receptor-dependent cell stimulation. PyMT-expressing Cos7 cells provided an environment where transcription of an HIV provirus was activated. PyMT expression induced the activity of both enhancer- and promoter-dependent HIV-LTR luciferase vectors. Induction of the HIV promoter domain depended on Sp1-binding sites and could be blocked by Wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K). This indicates that PyMT-induced HIV transcription and replication are controlled by both the enhancer and promoter domains of the HIV-LTR. The latter, but not the former, was induced in a PI3K-dependent way. Thus at least 2 different transduction pathways appear to collaborate for induction of full HIV genome transcription in activated cells.

Androstadienes↗
PubMed1994

Biosynthesis and processing of the Autographa californica nuclear polyhedrosis virus gp64 protein.

gp64 is a major virion envelope glycoprotein of the baculovirus Autographa californica multicapsid nuclear polyhedrosis virus (AcMNPV). gp64 plays an important role in AcMNPV infection, probably mediating penetration of one form of the virus into host cells through the endocytic pathway. gp64 also represents an excellent probe for studying the membrane glycoprotein processing capabilities of baculovirus-infected insect cells, which are used widely as a eucaryotic expression system. The goals of this study were to characterize gp64 biosynthesis and processing and determine how N-glycosylation and N-linked oligosaccharide processing influence the fate and function of gp64 in AcMNPV-infected insect cells. We found that gp64 was synthesized in a biphasic fashion, with peaks at 8 and 24 hr postinfection in both the intracellular and extracellular fractions. Interestingly, the first peak preceded detectable budded virus (BV) production, suggesting that gp64 is shed from infected cells early in infection. Transcriptional regulation accounted for the biphasic mode of gp64 protein synthesis, as transcription initiated at a consensus early motif during early times of infection, at a late motif during late times of infection, and there was a lag between the peak of early and the onset of late transcription. In vitro transcription-translation assays showed that the second ATG in the AcMNPV gp64 long open reading frame is used as the translational initiation codon and that downstream sequences encode a functional signal peptide. Pulse-chase analyses, endoglycosidases, and various inhibitors were used to show that some N-linked oligosaccharides on gp64 are processed by glucosidases and alpha-mannosidases in AcMNPV-infected insect cells. These experiments also revealed that at least two differentially processed gp64 glycoforms are produced in these cells and that both can reach the cell surface and assemble into progeny BV. However, N-linked oligosaccharide processing was not required for gp64 cell surface expression, its assembly into infectious BV, or its fusogenic activity. This suggested that any gp64 glycoform produced during infection, regardless of its N-linked carbohydrate structure, can have essentially normal biological properties. By contrast, transport of gp64 to the cell surface, production of infectious BV, and fusogenic activity were reduced in the absence of N-glycosylation, indicating that this modification is necessary for optimal gp64 function.

Amino Acid Sequence↗
PubMed1994

Regulation of metallothionein-I+II levels in specific brain areas and liver in the rat: role of catecholamines.

The role of the catecholamines noradrenaline, adrenaline and dopamine on metallothionein (MT) levels of specific areas of the rat brain has been studied. MT-I or MT-I + II levels were measured by radioimmunoassay using specific antibodies that cross-react only slightly with human MT-III (growth inhibitory factor, GIF). The inhibition of tyrosine hydroxylase with alpha-methyl-p-tyrosine (MPT), which depletes brain dopamine, noradrenaline, and adrenaline, increased MT levels in all brain areas studied (frontal cortex, cortex, medulla oblongata plus pons, midbrain, striatum, hippocampus, hypothalamus, and cerebellum) when considering the results of two separate experiments. The alpha- and beta-receptor blockers, phentolamine, and propranolol, alone or together, did not increase brain MT levels in any area of the brain, suggesting that the effect of MPT in vivo is related to inhibition of the synthesis of dopamine rather than of noradrenaline and adrenaline. Dopamine, noradrenaline, and serotonin increased MT-I levels in primary cultures of neurons, whereas decreased them in astrocyte-enriched primary cultures. Since MT-I levels are about ten times higher in astrocytes than in neurons, the increased brain MT levels induced by MPT may reflect the suppression of the normal inhibitory effect of dopamine on astrocyte MT levels. The increase in MT concentrations induced in most parts of the brain by immobilization stress was not prevented by MPT, phentolamine, or propranolol, suggesting that it was not mediated by the central monoamines.

Animals↗
PubMed1994

Implication of protein kinase C in IL-2-mediated proliferation and apoptosis in a murine T cell clone.

Several reports have suggested that protein kinase C plays an essential role in T cell activation and apoptosis. The recent synthesis of the selective protein kinase C inhibitor, GF109203X, has made it possible to test the relevance of protein kinase C in T cell proliferation and apoptosis. We report that the use of GF109203X, in concentrations that are below its toxicity limits, inhibits IL-2-dependent proliferation in murine T cells expressing intermediate or high-affinity IL-2R (TS1 beta and TS1 alpha beta). In addition, GF109203X reverts the suppression of apoptosis mediated by IL-2 or IL-2+ dexamethasone. The use of the phorbol ester PMA, a protein kinase C activator, allows a bypass of the IL-2/IL-2R interaction in the suppression of apoptosis mediated by dexamethasone or IL-2 withdrawal in TS1 beta cells but not in TS1 alpha beta cells. Taken together, our data indicate that activation of protein kinase C is an important step in IL-2-mediated proliferation and in suppression of apoptosis.

Animals↗
PubMed1994

Bilateral sacroiliac dislocation with intrapelvic intrusion of the lumbosacral spine. A case report.

A patient sustained bilateral sacroiliac dislocation in which the proximal part of the sacrum was displaced 10 cm anteriorly and 6 cm inferiorly into the pelvis. Stabilisation was initially obtained with an external fixator. Operation was carried out later: reduction was achieved by overhead skeletal traction using sublaminar wires; two screws were inserted through each sacroiliac joint and the two fragments of the sacrum were wired in place.

Adult↗
PubMed1994

Superovulatory response of ovarian follicles of Wave 1 versus Wave 2 in heifers.

Experiments were designed to test the hypotheses that ovarian follicular response to superstimulatory treatment initiated during Wave 1 is equivalent to that of Wave 2, and recovery rate and quality of ova embryos derived from follicles of Wave 1 are equivalent to those derived from follicles of Wave 2. In a preliminary experiment (Experiment 1), heifers were given Folltropin-V (20 mg NIH-FSH-P1, im, bid for 5 d) beginning the day after emergence of the first (n=10) or second (n=10) follicular wave of the estrous cycle, equivalent to approximately Day 1 and Day 10, respectively (Day 0=ovulation). Luteolysis was induced with cloprostenol (500 mug im, bid) on the fourth day of treatment. Fewer (P<0.05) ovulations per heifer were induced in the Wave 1 group than in the Wave 2 group (4.6+/-1.0 vs 9.1+/-1.3). However, the interval from wave emergence to initiation of treatment was found, in retrospect, to have been longer (P<0.05) in the Wave 1 group, i.e., treatment was initiated relatively later with respect to wave emergence. Experiment 2 was designed to correct this disparity and to initiate the same treatment protocol on the day of wave emergence rather than the day after (n=21 per Wave group). There was no difference between Wave 1 and Wave 2 groups in the interval from wave emergence to initiation of treatment (0.4+/-0.1 d), the number of ovulations detected by ultrasonography (6.6+/-1.0 vs 8.2+/-1.7), the number of CL detected at slaughter (6.5+/-0.9 vs 8.1+/-1.8), the total number of ova embryos recovered (5.2+/-0.7 vs 5.1+/-0.8), or the number of fertilized embryos collected (2.8+/-0.6 vs 3.0+/-0.6). In addition, there was no difference between groups in the proportion of heifers that ovulated in either experiment; collectively, luteolysis and ovulation was induced in 58 of 60 heifers. The results supported the general hypothesis that follicles and oocytes of the first and second follicular waves are equivalent in the response to superstimulatory treatment. Regardless of which follicular wave, initiation of treatment near the time of wave emergence appears critical for maximal superovulatory response. Because of the consistency in the time of emergence of Wave 1 (day of ovulation) and equivalence in superovulatory response, use of Wave 1 rather than subsequent follicular waves may be more convenient and time-sparing in superovulation programs; the day of estrus (day before ovulation) may be used as a consistent point of reference for the start of treatment.

Journal Article↗
PubMed1994

Characterization of SPf(66)n: a chimeric molecule used as a malaria vaccine.

SPf66 is a chemically synthesized 45 amino acid peptide derived from fractions of four different proteins of Plasmodium falciparum (83, 55 and 35 kDa and CS, the circumsporozoite protein) that elicits a protective immune response against malaria. In this paper we show the characterization of the SPf(66)n in batch 9 to be used in a field trial in young children at Ifakara in Tanzania. The analysis of SPf(66)n indicates that it is highly soluble in water and that the amino acid composition and sequence corresponds to that designed for the synthesis of the polypeptide. The packed product has a molecular weight ranging from 10 to 25 kDa. It is pure, free of metallic contaminants, atoxic and stable at 4 degrees C. The antibodies raised against this product in rabbits recognize the individual antigenic determinants of the molecule and the native epitopes of merozoites.

Amino Acid Sequence↗
PubMed1994

Can We predict patients at risk for persistent ectopic pregnancy after laparoscopic salpingotomy?

To identify factors that may predict patients at increased risk for persistent ectopic pregnancy after linear salpingotomy, we analyzed demographic, surgical, and biochemical variables retrospectively in 60 women who underwent laparoscopic linear salpingotomy, and compared data in those who developed persistent ectopic pregnancy (study group) versus those who were cured (controls). The two groups were similar with respect to demographic features and surgical findings. They did not differ significantly in gestational age and human chorionic gonadotropin (hCG) levels at time of surgery. There was, however, a significant difference in hCG dynamics when the average daily increase in the week before surgery was analyzed. Eleven (18%) women developed persistent ectopic pregnancy. The disorder did not occur in those whose hCG levels were flat or declining, whereas patients whose levels increased more than 40% per day had a significantly greater risk. In addition, at surgery, tubal bleeding was significantly more common in study patients than in controls (55 vs 9%, p <0.001). We conclude that hCG dynamics in the week before salpingotomy, and bleeding activity at surgery may identify patients who are the most likely candidates for persistent ectopic pregnancy.

Adult↗