Search PubMed⌕ Search

Biomedical subjects

C Garcia

Publications and source records attributed to C Garcia.

At least 163 records · Page 9Linked to original sources
PubMed1995

Sequence and domain organization of scruin, an actin-cross-linking protein in the acrosomal process of Limulus sperm.

The acrosomal process of Limulus sperm is an 80-microns long finger of membrane supported by a crystalline bundle of actin filaments. The filaments in this bundle are crosslinked by a 102-kD protein, scruin present in a 1:1 molar ratio with actin. Recent image reconstruction of scruin decorated actin filaments at 13-A resolution shows that scruin is organized into two equally sized domains bound to separate actin subunits in the same filament. We have cloned and sequenced the gene for scruin from a Limulus testes cDNA library. The deduced amino acid sequence of scruin reflects the domain organization of scruin: it consists of a tandem pair of homologous domains joined by a linker region. The domain organization of scruin is confirmed by limited proteolysis of the purified acrosomal process. Three different proteases cleave the native protein in a 5-kD Protease-sensitive region in the middle of the molecule to generate an NH2-terminal 47-kD and a COOH-terminal 56-kD protease-resistant domains. Although the protein sequence of scruin has no homology to any known actin-binding protein, it has similarities to several proteins, including four open reading frames of unknown function in poxviruses, as well as kelch, a Drosophila protein localized to actin-rich ring canals. All proteins that show homologies to scruin are characterized by the presence of an approximately 50-amino acid residue motif that is repeated between two and seven times. Crystallographic studies reveal this motif represents a four beta-stranded fold that is characteristic of the "superbarrel" structural fold found in the sialidase family of proteins. These results suggest that the two domains of scruin seen in EM reconstructions are superbarrel folds, and they present the possibility that other members of this family may also bind actin.

Acrosome↗
PubMed1995

Gastric mucosal pH and oxygen delivery and oxygen consumption indices in the assessment of adequacy of resuscitation after trauma: a prospective, randomized study.

OBJECTIVE: To compare gastric mucosal pH (pHi) and global oxygen variables [Oxygen Delivery Index (DO2I) and Oxygen Consumption Index (VO2I)] as indicators of adequacy of resuscitation after major trauma. METHODS: Twenty-seven patients were prospectively randomized into two groups: group 1 (n = 11), normalization and maintenance of pHi at or above 7.30; and group 2 (n = 16), maintaining a DO2I of 600 and a VO2I of > 150. The groups had statistically similar injury severity scores, lactate, and base deficit. RESULTS: The goals of therapy were achieved within 24 hours of admission in 10 of the 11 patients in group 1 and in 15 of the 16 patients in group 2. One patient (9.1%) in group 1 died. This patient had transient stabilization of pHi to 7.3 and subsequently had persistent mucosal acidosis. Of the 10 patients with pHi > 7.3 at 24 hours, 9 survived. In group 2, 5 (31.3%) died. Four of the 5 nonsurvivors had achieved DO2I and VO2I goals, but had pHi < 7.3 at 24 hours. A comparison of time taken for optimization of DO2I, VO2I, lactate, base excess, and pHi showed pHi and lactate as the variables different in survivors and nonsurvivors. Six of the 8 patients who developed multiple organ dysfunction syndrome had pHi < 7.3 at 24 hours. Persistently low pHi was the first sign of bacteremia (3 patients), small bowel gangrene or pregangrene (2 patients), intestinal anastomotic leak (2 patients), intra-abdominal hypertension (4 patients), and intra-abdominal abscess (5 patients). It was the first finding in all the nonsurvivors at least 72 hours before death. CONCLUSIONS: pHi may be an important marker to assess the adequacy of resuscitation. pHi monitoring may provide early warning for systemic complications in the postresuscitation period.

Adolescent↗
PubMed1995

A morphological study of cultured endodermal cells of chick embryo: characteristics of adhesion, spreading and locomotion.

A study is made of the morphological characteristics of the endodermic cells of the stage 5 chick embryo by means of in vitro cell culture techniques. The scanning electron microscope revealed that the endodermic cells in cultures were rounded, tended to be smooth and had few blebs and microvilli. Regarding cell projections typical of culture cells, such as filopodia, lamellipodia and pseudopodia, there was a noteworthy scarcity after 12 h growth, although greater cellular activity was observed at 24 h, characterized by the presence of filopodia and an ability of the cells to form clusters on the substratum. These facts show the morphological and adhesion movements of the endodermal cells studied to be related mainly with the presence of filopodia as the most abundant cell projections.

Animals↗
PubMed1995

Ultrastructural study of the early development of the sheep embryo.

An ultrastructural study of the different stages of pre-implantation in sheep was carried out, analysing the changes brought about mainly in the morula and blastocyst stages. The analysis of the embryos obtained showed a series of common characteristics in all stages, most noticeable being the presence of a high number of vesicles distributed in a uniform way in the cytoplasm, and also the presence of numerous electron-dense mitochondria in many varied forms. The most important ultrastructural modifications took place at the 16-cell stage and affected, principally, the nucleus, which presented numerous condensations of chromatin distributed along the nucleoplasm. The nucleoli adopted a reticular morphology, abandoning the compact aspects presented in the previous stage. These changes might be involved in the synthesis of embryonic RNA, and, accordingly, in the activation of the genome of this species. These data indicate that this stage is critical to the embryonic development and might be related to the blockage produced in the development of cultivated sheep embryos at the point of transition from 8 to 16 cells. Nevertheless, it should be pointed out that the first signs of modifications in the aspect of the nucleus are observed at the four-cell stage, being characterized by the appearance of vacuolated areas in the nucleolus, indicating the first signs of embryonic nucleic activity, which would anticipate the main change in the control of the protein synthesis.

Animals↗
PubMed1995

Effect of SR-49059, a vasopressin V1a antagonist, on human vascular smooth muscle cells.

The effects of SR-49059, a new nonpeptide and selective arginine vasopressin (AVP) V1a antagonist, were investigated in binding and functional studies on cultured human aortic vascular smooth muscle cells (VSMC). Characterization of human vascular V1a receptors, using a specific V1a radioiodinated ligand, showed that [125I]-linear AVP antagonist binding to human VSMC membranes was time dependent, reversible, and saturable. A single population of high-affinity binding sites (apparent equilibrium dissociation constant = 15 +/- 6 pM; maximum binding density = 36 +/- 5 fmol/mg protein, i.e., approximately 3,000 sites/cell) with the expected V1a profile was identified. Exposure of these cells to AVP dose-dependently produced cytosolic free [Ca2+] increase [AVP concentration required to obtain a half-maximal response (EC50) = 23 +/- 9 nM] and proliferation (EC50 = 3.2 +/- 0.5 nM). SR-49059 strongly and stereospecifically inhibited [125I]-linear AVP antagonist binding to VSMC V1a receptors [inhibition constant (Ki) = 1.4 +/- 0.3 nM], AVP-evoked Ca2+ increase [concentration of inhibitor required to obtain 50% inhibition of specific binding (IC50) = 0.41 +/- 0.06 nM], and the mitogenic effects induced by 100 nM AVP (IC50 = 0.83 +/- 0.04 nM). OPC-21268, another nonpeptide V1a antagonist, was more than two orders of magnitude less potent than SR-49059 in these models. However, the consistent affinity (Ki = 138 +/- 21 nM) and activity found with OPC-21268 on human VSMC in comparison with the inactivity already observed for other human V1a receptors (liver, platelets, adrenals, and uterus) strongly suggested the existence of human AVP V1a-receptor subtypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1995

Genetic and biochemical normalization in female carriers of Duchenne muscular dystrophy: evidence for failure of dystrophin production in dystrophin-competent myonuclei.

We studied 19 symptomatic female carriers of the Duchenne muscular dystrophy (DMD) gene. Most of these dystrophinopathy patients had had an erroneous or ambiguous diagnosis prior to dystrophin immunofluorescence testing. We assessed clinical severity by a standardized protocol, measured X-chromosome inactivation patterns in blood and muscle DNA, and quantitated the dystrophin protein content of muscle. We found that patients could be separated into two groups: those showing equal numbers of normal and mutant dystrophin genes in peripheral blood DNA ("random" X-inactivation), and those showing preferential use of the mutant dystrophin gene ("skewed" X-inactivation). In the random X-inactivation carriers, the clinical phenotype ranged from asymptomatic to mild disability, the dystrophin content of muscle was > 60% of normal, and there were only minor histopathologic changes. In the skewed X-inactivation patients, clinical manifestations ranged from mild to severe, but the patients with mild disease were young (5 to 10 years old). The low levels of dystrophin (< 30% on average) and the severe symptoms of the older patients suggested a poor prognosis for those with skewed X-inactivation, and they all showed morphologic changes of dystrophy. The random inactivation patients showed evidence of biochemical "normalization," with higher dystrophin content in muscle than predicted by the number of normal dystrophin genes. Seventy-nine percent of skewed X-inactivation patients (11/14) showed genetic "normalization," with proportionally more dystrophin-positive nuclei in muscle than in blood. In 65% of the skewed X-inactivation patients, dystrophin was not produced by dystrophin-positive nuclei; an average of 20% of myofiber nuclei were genetically dystrophin-positive but did not produce stable dystrophin. Biochemical normalization seems to be the main mechanism for rescue of fibers from dystrophin deficiency in the random X-inactivation patients. In the skewed X-inactivation patients, genetic normalization is active, but production failure of dystrophin by dystrophin-normal nuclei may counteract any effect of biochemical normalization. In the skewed X-inactivation patients, the remodeling of the muscle through cycles of degeneration and regeneration led to threefold increase in the number of dystrophin-competent nuclei in muscle myofibers (3.3 +/- 4.6), while dystrophin content was on the average 1.5-fold less then expected (-1.54 +/- 3.38). Our results permit more accurate prognistic assessment of isolated female dystrophinopathy patients and provide important data with which to estimate the potential effect of gene delivery (gene therapy) in DMD.

Adult↗
PubMed1995

[Mood disorders among inpatients in ambulatory and validation of the anxiety and depression scale HAD].

The revised Clinical Interview Schedule (CIS-R) and the Hospital Anxiety and Depression (HAD) Scale were used to estimate the prevalence of mood disorders among 78 consecutive admissions to a general medical ward in a university general hospital in Brazil (43 males and 35 females; mean age = 43.2yr). Interviewers also completed a 5-point symptom severity scales for anxiety and depression. The definition of cases of anxiety [and depression] was based on two criteria: a. score > or = 2 on the CIS-R section of anxiety [> or = 4 on the CIS-R sections of depression and depressive ideas]; and b. score > or = 2 on the clinical severity scale for anxiety [score > or = 2 on the clinical severity scale for depression]. A 39% prevalence rate of affective disorders was found. Sixteen (20.5%) patients met criteria for anxiety, most of the disorders being of mild severity. Twenty-sic patients (33%) were depressed, 7 of them in a moderate degree. The HAD was easily understood by the patients. Anxiety and depression subscales had internal consistency of 0.68 and 0.77, respectively. At a cut-off point of 8/9 sensibility and specificity were 93.7% and 72.6% for anxiety, and 84.6% and 90.3% for depression. HAD items correlated positively with the respective subscales. To a lesser degree, they also correlated with the alternative subscale. Our findings confirm the high prevalence of mood disorders among medical in-patients. In clinical practice, the HAD may have a useful role in detecting those patients requiring further psychological care.

Adolescent↗
PubMed1995

[Myocardial revascularization in left coronary trunk lesion in patients over 65 years old].

PURPOSE: To study the short and long-term follow-up of patients with left main coronary artery disease (LMCAD) and age over 65 years, by comparing the results with patients under 65 years-old. METHODS: Twenty-two patients with LMCAD and mean age of 69 +/- 3.5 years (group I) were underwent isolated coronary artery bypass grafting (CABG) and compared to 31 patients with LMCAD, mean age of 54 +/- 7 years (group II), who also underwent isolated CABG. The life-table Kaplan-Meyer method was used to estimate the post-operative survival. The chi-square and Student "t" test were used when necessary. RESULTS: Despite higher operative mortality in group I (9.1% x 3.2%), the difference was statistically not significant. The operative morbidity was similar in both groups. Actuarial survival at 4 years was 85% in group I and 95% in group II. Actuarial survival free of cardiac events was 69% in group II and 75% in group II. CONCLUSION: The CABG is well tolerated and had low morbidity and acceptable mortality in old patients with LMCAD. The long-term survival in these patients was very similar to the younger patients.

Actuarial Analysis↗
PubMed1995

Flow cytometric DNA analysis of fine-needle aspirates of prostatic benign lesions.

Fine-needle aspiration samples from 54 consecutive patients suffering from prostatic benign lesions were analyzed for both cytological diagnosis and DNA cell content, by means of standard cytological criteria and flow cytometry, respectively. Of these patients, 13 displayed prostatitis: three being classified as acute prostatitis, 7 as chronic and 3 as granulomatosous prostatitis. All cases had a diploid DNA cell content, with a mean percentage of S-phase cells of 1.8 +/- 2.7%. Although no major differences were detected between patients with and without prostatitis, the former group had a slightly higher proportion of S-phase cells (1.4 +/- 2.2% vs 2.7 +/- 3.7%). Moreover, within those patients with prostatitis, acute prostatitis cases showed the highest proliferation rates although differences did not reach statistical significance.

Biopsy, Needle↗
PubMed1995

[Juvenile polyposis in 2 patients of the same family].

Two cases of juvenile familiar polyposis (one 40-year-old male and his 14-year-old daughter) are presented. The girl presented intermittent rectal bleeding since the age of 10 with growth retardation and chronic anemia. The child was treated by colectomy with more than 100 juvenile polyps without adenomatous alterations being observed in the surgical specimen. Juvenile gastric polyps were also endoscopically observed. The father underwent sigmoidectomy for a adenomatous polyp of this localization. Later review of the surgical specimen demonstrated a juvenile polyp with zones of adenomatous alterations. The diagnostic difficulties of this rare entity and the therapeutic options available are discussed.

Adenomatous Polyposis Coli↗
PubMed1994

Steroid receptor-mediated modulation of CD4+CD62L+ cell homing. Implications for drug abusers.

Naive human T cells home to peripheral lymph nodes via the leukocyte endothelial cell adhesion molecule-1 (LECAM-1, l-selectin, CD62L, Leu8 antigen) they express. We enriched populations of CD4+CD62L+ cells (attachment of Leu8+ T cells to flasks coated with anti-mouse IgG (AIS); Leu8+ T cells, 82.3% pure (+/- 2.3%), enriched for CD4+ cells by incubation over flasks coated with anti-CD4 antibody--this 3-4-day procedure yields an 88 +/- 1.4% recovery. Cells were treated with dexamethasone in vitro for 24-48 h, and monitored by flow cytometry. We found severe toxicity by this steroid at high concentration (10(-6) M: 35% decrease in CD62L+ T cells, 22% drop specifically in CD4+CD62L+ cells), suggesting the onset of receptor-mediated apoptotic events. The toxicity was dose dependent (5% and 7% drop in CD62L+ T and CD4+CD62L+ cells, respectively, at 10(-9) M, the concentration found in plasma 10 h following the administration of 1 mg dexamethasone). One mg of dexamethasone given to normal subjects leads to a 15-20% decrease in circulating CD4+CD62L+ cells at 10 h. This tends to be correlated with a drop in the number of glucocorticoid cytosolic receptors. Thus, steroids seem to modulate CD4+CD62L+ cell homing by means of receptor-mediated mechanisms.

Adult↗
PubMed1994

The disulfide linkages and glycosylation sites of the human natriuretic peptide receptor-C homodimer.

The natriuretic peptide receptor-C (NPR-C) constitutes greater than 95% of the natriuretic peptide binding sites in vivo. This cell surface glycoprotein is a disulfide-linked homodimer with a subunit molecular weight of 68,000. Two sources and types of ANP affinity-purified human NPR-C were used to map disulfide linkages and glycosylation sites of this receptor by mass spectrometry: the extracellular domain obtained by papain cleavage of a receptor-IgG fusion protein expressed in Chinese hamster ovary cells, and a baculovirus/Sf9-expressed cytoplasmic truncation mutant in which 34 of 37 cytoplasmic domain amino acids were deleted. Two intramolecular disulfide bonded loops were found in the 435 amino acid extracellular domain (C63-C91, C168-C216). The juxtamembrane residues C428 and C431 are involved in homodimer formation, confirmed by site-directed mutagenesis of full-length NPR. Three of the four potential Asn-linked glycosylation sites are occupied: N41 (complex), N248 (high mannose), and N349 (complex; partial occupancy). These data describe the intra- and intermolecular linkages in NPR-C, providing a model for the homologous guanylyl cyclase receptors, NPR-A and NPR-B; both of the cyclase receptors likely contain the first amino-terminal 29 amino acid loop, but only NPR-A possesses the second 49 amino acid loop in common with NPR-C.

Amino Acid Sequence↗
PubMed1994

Binding of [3H] SR 49059, a potent nonpeptide vasopressin V1a antagonist, to rat and human liver membranes.

The new potent and selective nonpeptide vasopressin V1a antagonist, SR 49059, was tritiated and used for the characterization of rat and human liver AVP V1a receptors. Binding of [3H] SR 49059 was time-dependent, reversible and saturable. A single class of high affinity binding sites was identified with Kd values of 0.63 +/- 0.13 and 2.95 +/- 0.64 nM, in rat and human liver membranes, respectively. The maximal binding capacity (Bmax) was about 7 times higher in rat than in human liver preparations. The relative potencies of several AVP/oxytocin agonists or antagonists to inhibit [3H] SR 49059 binding confirmed that this ligand labeled a homogeneous population of sites with the expected AVP V1a profile. Furthermore, [3H] SR 49059 or unlabeled SR 49059 displayed only slight species differences between rat and human V1a receptors, whereas OPC-21268, another nonpeptide V1a antagonist, exhibited a high species-related potency with more than 500 fold higher affinity for rat than for human liver V1a receptors. Thus, [3H] SR 49059 is the first nonpeptide AVP V1a ligand reported having highly specific activity, stability, specificity and affinity. This makes it a suitable probe for labeling AVP V1a receptors in rat and also in human tissues.

Animals↗
PubMed1994

Effect of a new, potent, non-peptide V1a vasopressin antagonist, SR 49059, on the binding and the mitogenic activity of vasopressin on Swiss 3T3 cells.

The effects of SR 49059, a new non-peptide, selective arginine vasopressin (AVP), V1a antagonist, were investigated both on AVP's receptors and on the mitogenic effects of AVP on Swiss 3T3 fibroblasts. We characterized the AVP V1a receptors on Swiss 3T3 cell membranes using the new highly specific AVP V1a radioiodinated ligand, 125I-linear AVP antagonist. Specific binding of the 125I-linear AVP antagonist was saturable, time-dependent and reversible. A single class of high affinity binding sites was identified with an apparent Kd of 40 +/- 20 pM and a Bmax of 63 +/- 20 fmol/mg protein. 125I-Linear AVP antagonist binding to its receptors was potently inhibited in a concentration-dependent manner by AVP, by the peptide V1a antagonist d(CH2)5Tyr(Me)AVP and by the synthetic V1a antagonist, SR 49059 (IC50 in the nanomolar range) while OPC-21268, another non-peptide compound, was about 100-fold less potent. Both DDAVP, a selective V2 agonist, and oxytocin exhibited low affinity (IC50 > 1 microM) in agreement with the AVP V1a nature of the site identified on Swiss 3T3 cells. In addition, the broad-spectrum antiproliferative agent [Arg6, D-Trp7,9, MePhe8] substance P (6-11), was also able to interact at 3T3 AVP V1a receptors (IC50 = 395 +/- 170 nM). The mitogenic effects of AVP on quiescent Swiss 3T3 cells, assessed through [3H]thymidine incorporation, were selectively, stereospecifically and strongly inhibited by SR 40959 (IC50 = 14 +/- 2 nM) while OPC-21268 was inactive up to 220 nM. SR 49059 was even about six times more efficient than d(CH2)5Tyr(Me)AVP in inhibiting AVP-induced DNA synthesis. Moreover, SR 49059 fully inhibited Swiss 3T3 fibroblast proliferation since it completely blocked AVP-stimulated 3T3 cell growth from the G1/G0 into the S/G2M phase, as evidenced by cell cycle analysis using a cytofluorometer. In summary, SR 49059, through direct interaction at AVP V1a receptors, exerts the most potent antiproliferative effect yet described for any V1a antagonist on Swiss 3T3 cells.

3T3 Cells↗
PubMed1994

Genetic heterogeneity among craniosynostosis syndromes: mapping the Saethre-Chotzen syndrome locus between D7S513 and D7S516 and exclusion of Jackson-Weiss and Crouzon syndrome loci from 7p.

Saethre-Chotzen, Crouzon, and Jackson-Weiss syndromes are craniosynostotic autosomal dominant conditions with a wide variability in expression. Saethre-Chotzen has been mapped to chromosome 7p by L. A. Brueton et al. (1992, J. Med. Genet. 29: 681-685), the Greig cephalopolysyndactyly gene was identified at 7p13 by A. Vortkamp et al. (1991, Nature 352: 539-540), and many cases of craniosynostosis have been associated with 7p deletions. We confirmed linkage of the Saethre-Chotzen syndrome locus to chromosome 7p. The tightest linkage was to locus D7S493 (Z = 5.04, theta = 0.00), and linkage and haplotype analyses refined the location of the gene to the region between D7S513 and D7S516. Jackson-Weiss and Crouzon syndrome loci were analyzed using markers spanning the entire 7p arm and were excluded, proving that they are nonallelic to Saethre-Chotzen, Greig cephalopolysyndactyly, and the del(7p) syndromes.

Abnormalities, Multiple↗
PubMed1994

Ultrastructural localization of lectin receptors in the preimplantation ovine embryo.

BACKGROUND: Preimplantation development of mammalia is characterized by cell surface changes functioning in intercellular communication and adhesion. The glycoconjugate role in cellular interactions has been analysed for several groups but not in sheep embryos. The binding patterns of eleven lectins during sheep preimplantation development were investigated and the role of glycoconjugates in early development was discussed. METHODS: Ultrathin sections from preimplantation ovine embryos (3-7 days) were incubated with different colloidal gold conjugated lectins and the frequency of gold particles on the cell membrane, some organelles, and the zona pellucida was evaluated. RESULTS AND CONCLUSIONS: We observed a higher staining of WGA, DBA, and SBA lectins in the intercellular contact zone with respect to the free cell surface of blastomeres during cleavage. This indicates that the N-acetyl galactosamine and N-acetyl glucosamine residues may be involved in sheep morula compaction. In contrast, the trophoblast cell displays an increase of staining of some lectins previously identified during cleavage (LcH, WGA, SBA, MPA, and PNA) on the free membrane, and a lack of sugar residues in the intercellular surface. This polarization of the trophoblast cell surface is not observed in the inner cell mass and could provide a mechanism for differentiation within the blastocyst. Intracytoplasmic vesicles show a cytochemical identity with lysosomes in the blastocyst (abundant GlcNAc and Man/Glc residues) that may reflect a functional relationship between both organelles in an intracellular cycle. The zona pellucida presents abundant GalNAc, GlcNAc, and Gal residues during preimplantation ovine development.

Animals↗