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Biomedical subjects

M Garcia

Publications and source records attributed to M Garcia.

At least 199 records · Page 11Linked to original sources
PubMed1993

Levels of ecdysteroid-like material in adults of Nippostrongylus brasiliensis during the intestinal phase.

Total ecdysteroid-like immunoreactive material was assayed and quantified in adults of the parasitic nematode N. brasiliensis during the intestinal phase in the rat in order to detect possible physiological fluctuations in titre. Worms of the same sex isolated from one rat were pooled in order to quantify ecdysteroids using enzyme immunoassay (EIA). The concentration of ecdysteroids fluctuated during adult life according to the sex and the age of the parasite. Important differences of levels of ecdysteroid-like compounds between the two sexes of parasites were noted particularly at 128 and 168 h post-infection. The peak at 128 h, present in female, but not in male worms, corresponds to the time of egg-laying. Following HPLC-EIA analysis, the presence of ecdysone, 20-hydroxyecdysone and apolar ecdysteroid-like material was ascertained during this peak. The physiological role and the possible origin of ecdysteroids in this nematode are discussed.

Animals↗
PubMed1993

Pitfalls in the echo-Doppler diagnosis of prosthetic valve disorders.

Assessment of artificial heart valves is a classic example of pitfalls in Doppler and color flow echocardiography. These limitations should be analyzed in the context of the most common clinical conditions associated with prosthetic valve dysfunction, that is, assessment of stenosis, regurgitation, endocarditis, and source of emboli. Estimation of the mean transvalvular gradient in addition to valve areas may avoid potential problems of over- or underestimation of stenotic lesions. The combination of acoustic attenuation, acoustic shadowing, and jet(s) eccentricity makes accurate grading of prosthetic regurgitation difficult and often frustrating. Reverberations and side lobe are frequent artifacts that decrease the ability of two-dimensional echocardiography to identify endocarditis-induced lesions such as vegetations and abscesses, as well as potential sources of emboli such as thrombus and atrial septal abnormalities. Transesophageal echocardiography has provided a new window in the evaluation of prosthetic cardiac valve function. With this approach, high frequency, high resolution transducers greatly improve the quality of ultrasound and color flow Doppler images that result in a higher diagnostic yield. In patients with suspected mitral prosthesis malfunction, transesophageal echocardiography is the method of choice. Contrast study during the transesophageal examination increases the sensitivity to detect potential sources of emboli such as patent foramen ovale. The improvement in diagnostic accuracy may allow one to avoid further diagnostic tests and, in selected patients, it may facilitate optimal timing of a surgical intervention.

Echocardiography, Doppler↗
PubMed1993

GPI-anchored proteins associate to form microdomains during their intracellular transport in Caco-2 cells.

In this study, we have investigated the possibility that glycosyl-phosphatidylinositol (GPI)-anchored proteins form insoluble membrane complexes in Caco-2 cells and that transmembrane proteins are associated with these complexes. GPI-anchored proteins were mainly resistant to Triton X-100 (TX-100) extraction at 4 degrees C but fully soluble in n-octyl-glucoside. Resistance to Triton X-100 extraction was not observed in the endoplasmic reticulum but appeared during transport through the Golgi complex. It was not dependent upon N-glycosylation processing, or pH variation from 6.5 to 8.5, and was not affected by sterol-binding agents. Other apical or basolateral transmembrane proteins were well solubilized in TX-100, with the exception of sucrase-isomaltase, which was partly insoluble. We isolated a membrane fraction from Caco-2 cells that contained GPI-anchored proteins and sucrase-isomaltase but no antigen 525, a basolateral marker, or dipeptidylpeptidase IV, an apical one. These data suggest that GPI-anchored proteins cluster to form membrane microdomains together with an apical transmembrane protein, providing a possible apical sorting mechanism for intestinal cells in vitro that might be related to apical sorting in MDCK cells, and that other mechanisms might exist to sort proteins to the apical membrane.

Alkaline Phosphatase↗
PubMed1992

Activation of estrogen receptor transfected into a receptor-negative breast cancer cell line decreases the metastatic and invasive potential of the cells.

Breast cancers containing estrogen receptors are responsive to antiestrogen treatment and have a better prognosis than estrogen receptor-negative tumors. The loss of estrogen and progesterone receptors appears to be associated with a progression to less-differentiated tumors. We transfected the human estrogen receptor into the estrogen receptor-negative metastatic breast cancer cell line MDA-MB-231 in an attempt to restore their sensitivity to antiestrogens. Two stable sublines of MDA-MB-231 cells (HC1 and HE5) expressing functional estrogen receptors were studied for their ability to grow and invade in vitro and to metastasize in athymic nude mice. The number and size of lung metastases developed by these two sublines in ovariectomized nude mice was not markedly altered by tamoxifen but was inhibited 3-fold by estradiol. Estradiol also significantly inhibited in vitro cell proliferation of these sublines and their invasiveness in Matrigel, a reconstituted basement membrane, whereas the antiestrogens 4-hydroxytamoxifen and ICI 164,384 reversed these effects. These results show that estradiol inhibits the metastatic ability of estrogen receptor-negative breast cancer cells following transfection with the estrogen receptor, whereas estrogen receptor-positive breast cancers are stimulated by estrogen, indicating that factors other than the estrogen receptor are involved in progression toward hormone independence. Reactivation or transfer of the estrogen receptor gene can therefore be considered as therapeutic approaches to hormone-independent cancers.

Animals↗
PubMed1992

Pregnancy-dependent to ovarian-independent progression in mammary tumors delineated in primary culture: changes in signal transduction, growth factor regulation, and matrix interaction.

A model for the evolution of hormone-independent tumors from a pregnancy-dependent precursor is exemplified by the TPDMT-4[pregnancy-dependent (PD)] and T4OI96 [ovarian-independent (OI)] in vivo tumor lines developed in DDD mice. In vivo, the OI tumor grows rapidly in virgin mice and is more anaplastic than the PD tumor which, in virgin mice, grows as a hyperplastic alveolar gland from which tumors arise only during pregnancy. The regulation of the proliferation of these two tumors was compared in primary culture using a three-dimensional, serum-free, collagen gel cell culture system. In medium containing insulin, the growth of cell organoids from PD tumors was stimulated by the same factors that stimulate the growth of normal mammary epithelial cells from virgin or pregnant mice. These factors include progesterone and prolactin (but not estrogen), epidermal growth factor, basic fibroblast growth factor, linoleic acid, cyclic AMP, prostaglandin E2, phosphatidic acid, and lithium. Most of these tumors (about 80%) could not grow in medium with only insulin present; of those that did, growth was slow and was stimulated further by the above agents. PD tumor cells formed stellate colonies in the collagen matrix similar to those of normal cells. These findings show that the growth regulation of PD tumor cells is, in all aspects examined, similar to that of normal cells. In addition, the capacity for growth in the presence of only insulin (more autonomous growth) is not necessarily accompanied by deletions in responses to growth factors or hormones, or in lipid response pathways. In contrast, organoids from OI tumors needed only insulin for growth. The growth of some of these tumors was stimulated further by only basic fibroblast growth factor and phosphatidic acid. Cyclic AMP and agents that elevate intracellular cyclic AMP inhibited growth, the opposite of the response seen in normal or PD cells. OI organoids grew as cell masses rather than as stellate structures. These data show that while PD tumors are remarkably similar to normal cells in the regulation of their proliferation, OI tumors have incurred multiple defects in growth-regulatory pathways possibly including the production of autocrine growth factor(s). In addition, the ability of OI tumor cells to adhere to the collagen gel matrix and undergo normal morphogenesis is reduced. These results may highlight specific events required for the progression from ovarian dependency to ovarian independency related to the hormonal regulation of growth.

Animals↗
PubMed1992

Fine-needle aspiration biopsy of hepatic papillary cystadenocarcinoma in Caroli's disease.

A case of papillary adenocarcinoma arising in Caroli's disease (CD) in a 25-yr-old woman is reported. The diagnosis of malignancy was made by ultrasound-guided, fine-needle aspiration biopsy (FNAB). As there were no metastasis, a liver transplant was performed and the diagnosis was histologically confirmed. Only 22 cases of malignant transformation of CD have been reported to date, all among middle-aged subjects (mean age: 52 yr) of both sexes. Most of these reported cases (83%) were found to be bile duct adenocarcinomas with occasional reports of hepatocellular and undifferentiated carcinomas. Our case is the youngest reported to date and the first to be diagnosed cytologically.

Adult↗
PubMed1992

Relapsing illness due to Rochalimaea henselae in immunocompetent hosts: implication for therapy and new epidemiological associations.

Two previously healthy, immunocompetent men had persistent Rochalimaea henselae bacteremia with clinical relapses after courses of antibiotics to which the isolates were ultimately demonstrated susceptible in vitro. Both had sustained tick bites prior to their illnesses, thus demonstrating an association not previously identified, although suspected. The first patient had relapsing fever, constitutional symptoms, and an episode of aseptic meningitis despite therapy with amoxicillin, then with doxycycline, and then with ceftriaxone. Thereafter, he spontaneously became asymptomatic during a span of 2 months of persistent bacteremia. Finally, after 2 weeks of therapy with ceftriaxone plus gentamicin, followed by 4 weeks of therapy with oral ciprofloxacin, his bacteremia was cured. The second man had relapsing fever and constitutional symptoms after courses of tetracycline, then of chloramphenicol, and then of doxycycline. He became permanently asymptomatic after serial 2-week courses of chloramphenicol and erythromycin. The greater efficacy of lysis-centrifugation blood cultures in the recovery of R. henselae was noted.

Adult↗
PubMed1991

Carcinoembryonic antigen has a different molecular weight in normal colon and in cancer cells due to N-glycosylation differences.

Carcinoembryonic antigen, an apical membrane glycoprotein expressed in normal human colonic epithelial cells, colonic polyps, tumor, and tissue culture cell lines originating from colonic adenocarcinomas, is generally considered to have a molecular weight of 180,000. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis associated with immunoprecipitation or immunoblotting with both monoclonal (Mab 517 and Mab 601) and polyclonal antibodies, we observed that carcinoembryonic antigen was actually expressed as two discrete apparent molecular weight forms in normal tissues: a broad band averaging at Mr 200,000 and a sharp band at Mr 130,000. This constituted the phenotype of the normal colon. In cancer cells we detected a single band at Mr 170,000 or lower. This variation was mainly the consequence of a modification of the glycosylation pattern of the molecule since deglycosylation by N-glycanase or biosynthesis in the presence of tunicamycin always produced a single molecular weight form, whether or not the source of tissue was normal or cancerous. By close inspection of benign, moderately transformed, and carcinomatous human colonic polyps we noticed that this shift in the molecular weight of carcinoembryonic antigen preceded the detection of other cancer markers such as nonspecific cross-reacting antigen at Mr 95,000 or the histological modifications leading to malignant diagnosis. Carcinoembryonic antigen constitutes, therefore, an important model with which to study the modifications of the glycosylation pattern induced during cancer biogenesis.

Carcinoembryonic Antigen↗
PubMed1991

Acute epiglottitis in the adult.

Acute epiglottitis in the adult is a rare disease, which has shown an appreciable increase since the sixties and in our locality since 1984. We present a review of the cases registered in our hospital, analyzing their aetiology, evolution and treatment. The disease is most likely to be suspected in the presence of any patient having a sudden dysphagia, especially if he shows symptoms of an acute infection and a lack of oropharyngeal pathology.

Acute Disease↗
PubMed1991

Inhibition of proliferation of primary avian fibroblasts through expression of histone H5 depends on the degree of phosphorylation of the protein.

To obtain stable and constitutive expression of histone H5 at levels comparable to those observed in normal chicken erythrocytes, an avian self-inactivating retroviral vector was used to transfer the H5 gene into cells which do not express this protein. The vector, pDAH5, was obtained by removing the CAAT and TATA boxes of the 3'LTR of the avian leukosis virus RAV-2 and inserting the H5 sequence. Infection of QT6 quail cells with the recombinant virus (DAH5) led to the stable integration of the foreign H5 gene at low copy number, to the formation of correctly initiated mRNA transcripts and to the production of H5 protein. The amount of H5 expressed was equivalent to that of a mature chicken erythrocyte. Expression of histone H5 in DAH5 transformed cells, such as QT6 or AEV-ES4, transformed chicken embryo fibroblasts had only slight effects on the growth rate and did not inhibit cell replication. Conversely, the effect of H5 expression on normal quail and chicken fibroblasts was dramatic: cells acquired the aspect of quiescent fibroblasts, grew very slowly, and nuclei looked compacted, often extruded from the cell. The H5 histone produced in QT6-transformed cells was found to be phosphorylated while in normal chicken fibroblasts the protein lacked this posttranslational modification. It is proposed that the chromatin-condensing role of histone H5 is inhibited by its phosphorylation.

Animals↗
PubMed1991

Intrauterine release of oestriol in castrated rhesus monkeys induces local but not peripheral oestrogenic effects: a possible approach for the treatment and prevention of Asherman's syndrome.

Two types of oestrogen-medicated intrauterine devices (IUD) were studied in ovariectomized rhesus monkeys. An oestradiol (E2) fibre-wrapped IUD that released E2 at a rate of 3.57 micrograms/cm/day, or an oestriol (E3) fibre-wrapped IUD that releases E3 at a rate of 6.4 micrograms/cm/day, was inserted in eight animals and left in place for 4 weeks. Serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), E2 and E3 were determined by radioimmunoassay for 1 week before the IUD insertion, during the time the IUD was in place, and for 3 weeks after its removal. Uterine histology was performed at the time of IUD insertion and removal by light and transmission electron microscopy. Both E2 and E3 IUDs induced similar histological changes in the uterus, i.e. four- to five-fold increase in endometrial thickness, a shift of the gland/stroma ratio from 1:4 to 1:1, transformation to a marked pseudostratified epithelium with pronounced coiling of the glands, appearance of subnuclear and luminal secretion and, finally, change from spindle-dense stromal cells to plump eosinophilic cells. Oestradiol fibre-wrapped IUDs produced circulating E2 levels of 150-200 pg/ml during the entire 4 weeks. FSH and LH levels were decreased to an average of 55% and 65% from a castration baseline (P less than 0.001 and P less than 0.05, respectively). Oestriol fibre-wrapped IUDs produced circulating E3 levels of 100-250 pg/ml. However, FSH and LH levels were not altered in this group. The specific local oestrogenic effect of E3-IUDs without affecting the pituitary secretion of gonadotrophins, suggests their possible application in cases in which an exclusively oestrogenic effect at the uterine level, such as in Asherman's syndrome, is desired.

Animals↗
PubMed1991

Tetrasomy 9p: an emerging syndrome.

An infant with non-mosaic 9p tetrasomy is described. The tetrasomy apparently results from a translocation involving the 9qh region. All the cells analyzed from multiple banding techniques from lymphocyte culture as well as skin fibroblast culture were 9p tetrasomic. The infant, who had the characteristic dysmorphic features of 9p tetrasomy, survived for 2 months. Prominent features included: low birth weight, severe retardation, brachycephaly with large anterior fontanelle, hypertelorism with short bilateral palpebral fissures, beaked nose, bilateral cleft lip and palate, and low-set, malformed ears. Skeletal anomalies, ambiguous genitalia and heart defect were also observed. These features are highly characteristic of the 9p tetrasomy syndrome based on six pure tetrasomy and four cases of tetrasomy that included part of the 9qh region.

Abnormalities, Multiple↗