Biomedical subjects
Publications and source records attributed to C Garcia.
We report on a case of Fryns' syndrome diagnosed prenatally in a woman with no family history of this disorder. A computerized database was used for the differential diagnosis. Intensive perinatal care resulted in prolonged survival, which is unusual in individuals with Fryns' syndrome. This case provides further delineation of the developmental course in patients with this condition.
We previously found a potent inhibitor of the Na-K-Cl cotransport system in urines from salt-loaded rats (C.I.F. = cotransport inhibitory factor, ref. 1). Here we extracted an urinary fraction (approximately 1% urine dry weight), free from immunoreactive A.N.P. and digoxin activity, which: (i) potently inhibited cotransport fluxes in MDCK (Madin and Darby canine kidney] cells and in human erythrocytes, (ii) inhibited Na(+)-dependent chloride/bicarbonate exchange with 2-3 times less potency than cotransport and (iii) strongly increased natriuresis and diuresis after i.v. infusion in rats with no significant change in kaliuresis (salidiuretic action reduced by probenecid). Therefore, C.I.F. seems to be a new natriuretic factor with part, but not all the biological profile of loop diuretic drugs.
Initiation factor IF3 plays an essential role in the initiation of protein translation by binding to the 30S ribosomal subunit and selecting a proper tRNA(fMet)/initiation codon complex. The domain structure of IF3 from Escherichia coli has been investigated by limited proteolysis followed by mass spectrometry and protein sequencing of the resulting peptides. This analysis revealed a highly segmented structure with two independent domains connected by a charged linker peptide, highly susceptible to proteolytic cleavage. The N-terminal domain is very stable and comparison of its 2-D NMR spectrum with that of intact IF3 revealed that it retains its three-dimensional fold.
The phenotypic characteristics of expressed tyrosine hydroxylase protein have been precisely analysed in the rat nucleus tractus solitarius, which contains the majority of A2 noradrenergic and C2 adrenergic neurons of the medulla oblongata. This study was based upon quantitative analysis of immunohistochemical and immunoradioautographic staining of tyrosine hydroxylase protein in serial coronal sections. In control rats, there were few tyrosine hydroxylase-expressing cell bodies which express less than 2% of the immunoradiolabeled tyrosine hydroxylase protein measured in the structure. These cell bodies were scattered throughout an extensive immunopositive neuropile, which precisely delimited the topological space of the nucleus tractus solitarius quantiatively reconstructed using a polar coordinate system. The quantification of tyrosine hydroxylase tissue concentration from immunoradioautograms allowed us to subdivide the structure into two distinct regions. The posterior region of the nucleus tractus solitarius, which mainly corresponds to the A2 cell group, contains a relatively high tissue concentration of tyrosine hydroxylase protein (18.56 +/- 0.154 units per mg of tissue). The anterior region, which mainly corresponds to the C2 cell group, exhibits a relatively low concentration (12.09 +/- 0.81) of this protein. Three days after an intraperitoneal injection of RU24722, there was a strong increase (90 +/- 17%) in tyrosine hydroxylase protein content only in the anterior region of the nucleus tractus solitarius. This increase was associated with a dramatic elevation (142 +/- 20%) in the number of tyrosine hydroxylase-expressing cell bodies. The additional cell bodies were mainly located inside the initial perikarya-containing area.(ABSTRACT TRUNCATED AT 250 WORDS)
The [3',5']-ditritio-alpha-fluoromethyl-tyrosine 4 (specific activity 15.0 Ci/mmol) has been synthesized and used as a radioactive probe for rat neuronal tyrosine hydroxylase (TH). The route of synthesis for the preparation of 3 and 4 allowed us to not only introduce a fluorine atom into 3/4 using an inorganic source of fluorine (CsF), but also to take advantage of the high-yielding cyclization of (alpha,beta)-acetamido alcohols mediated by diethylaminosulfur trifluoride (DAST) to give the corresponding oxazolines. The distribution and metabolism of 4 have been studied in control conditions within the rat locus caeruleus (LC). Intracisternal injection of 20 microCi of 4 was followed by a rapid disappearance of 4 (t1/2 = 1.5 h) and by a specific accumulation of radioactivity into the LC anatomical limits. This was investigated each 140 microns along the caudo-rostral axis of the noradrenergic nucleus. In each anatomical interval, its distribution correlated nicely with already described caudo-rostral distribution of TH in noradrenergic cells. Thus, 4 may provide a reliable measure of TH activity in such catecholamine structures.
The present study was carried out to investigate the effect of chronic heat exposure on tyrosine hydroxylase (TH) protein content in catecholaminergic rat brain-stem areas such as the anterior (LCA) and posterior (LCP) locus coeruleus, the substantia nigra (SN), the ventral tegmental area, and the dorsomedial (DMM) and the ventrolateral medulla and in the adrenal gland (AG). Male Sprague-Dawley rats were exposed to 34 degrees C during 3, 7, or 14 days. Controls were kept at 25 degrees C for the same period. In the LCA, TH content was decreased on day 7 (-34%) and 14 (-37%) of heat exposure. In the SN, TH protein content was decreased on day 7 (-25%) and 14 (-20%) after 34 degrees C. In the DMM cell group, 14 days at 34 degrees C produced a decrease (-20%) of TH content. In all of these structures, TH content variations were correlated with body temperature variations. In the AG, TH content increased progressively to peak (+31%) after 14 days of chronic heat exposure. This increase was also associated with body temperature modification. The selective and body temperature-related response to long-term TH protein content variations following chronic heat exposure observed in the LCA, SN, DMM, and AG could represent an adaptive physiological response of these catecholaminergic cells.
The purpose of the study was to examine how young children interact in the context of learning fundamental motor skills. Twenty-nine preschool children were observed during a period of six consecutive months while they were participating in their daily motor skills program. Fieldwork research methodology was used and data were collected using participant observation techniques. During data analysis, emerging patterns were identified and cross-referenced against data collected from other sources (triangulation). Girls were found to interact in a cooperative, caring, and sharing manner. Boys were found to interact in a competitive, individualized, and egocentric manner. A cultural pattern of cooperative interaction among Asian children was found. In addition, both boys and girls tried to maintain their gender style of interaction when dealing with the opposite sex. This study reveals several aspects of the social environment that may need to be considered when teaching motor skills to young children.
OBJECTIVES: Limulus anti-lipopolysaccharide factor, an 11.8-kilodalton peptide isolated from amebocytes of Limulus polyphemus inhibits the biologic activities of endotoxin in vitro, including gelation of Limulus amebocyte lysate. A recombinant version of Limulus anti-lipopolysaccharide factor, termed endotoxin neutralizing protein, has now been expressed in yeast. Endotoxin-neutralizing protein was evaluated for its potential prophylactic and therapeutic effects in rabbits challenged with Escherichia coli endotoxin. DESIGN: Controlled animal trial. SETTING: Animal research laboratory. SUBJECTS: A total of 112 New Zealand white rabbits were studied. INTERVENTIONS: Rabbits were challenged with an LD80 dose of E. coli endotoxin (100 micrograms/kg); control animals (n = 52) were treated with saline solution at the time of endotoxin challenge; experimental animals received endotoxin-neutralizing protein 2.5 mg/kg prechallenge (n = 20), 5.0 mg/kg prechallenge (n = 20), or 5.0 mg/kg 30 mins postchallenge (n = 20).
Tumor necrosis factor alpha (TNF-alpha) seems to play an important role in the pathogenesis of the adult respiratory distress syndrome (ARDS). This study was designed to determine the effect of TNF-alpha and pentoxifylline (PTXF) on surfactant synthesis by isolated human type II pneumocytes. In order to isolate the pneumocytes, lungs obtained from both previously healthy multiple organ donors (n = 11) and patients who underwent surgical excision for lung cancer (n = 8) were used. Surfactant synthesis was measured by the incorporation of labeled glucose into the two most important phospholipid components of surfactant: phosphatidylcholine (PC) and phosphatidylglycerol (PGL). The pneumocytes of the donor group showed a greater degree of PC synthesis than those from the cancer group (3.44 +/- 0.19 versus 2.15 +/- 01.5 pmol/micrograms protein, p < 0.001). The synthesis of PC by pneumocytes in both the donor (1.13 +/- 0.19 versus 3.44 +/- 0.19 pmol/micrograms protein, p < 0.01) and cancer (0.99 +/- 0.11 versus 2.15 +/- 0.15 pmol/micrograms protein, p < 0.01) groups was decreased by TNF-alpha (100 ng/ml). This effect was blocked by PTXF (100 micrograms/ml), a substance that also increased PC production in the control-group pneumocytes from cancer patients, the final PC levels being similar to those of the donors in the absence of TNF-alpha. These results suggest that one of the mechanisms of TNF-alpha participation in the pathophysiology of ARDS is inhibition of surfactant synthesis, and support the hypothesis of in vivo production of TNF-alpha in lung-cancer patients, with subsequent chronic exposure of the lung epithelial cells to this cytokine.(ABSTRACT TRUNCATED AT 250 WORDS)
The microenvironment of the chick thymus has been examined during development using lectin histochemistry. We have assayed WGA, Con A, RCA-I and TPA on thymic sections from 13, 15, 17 and 19 d chick embryos and 0, 5, 10 and 15 d chicks. All lectins were immunoperoxidase and colloidal gold-conjugated for transmission electron microscope observations. WGA labelled both the cortical and medullary thymic stroma at all the stages analysed. An intense reaction to WGA was observed in the subcortical region from stage 18 embryos to 5 d chicks. On the other hand, WGA did not stain medullary areas of the chick thymus. Con A lectin detected several cell clusters of stromal cells and thymocytes in cortical regions. These clusters could represent a lymphostromal complex with which Con A receptors are associated, probably in relation to cell adhesion. The residues detected by RCA were distributed both in stromal cells and thymocytes of the developing chick thymus. There was an increase of the reaction to RCA between the 19 d embryos and the 5 d chicks. This increase might be interpreted in terms of the secretion of thymic humoral factors at these stages. The thymic stromal cells stained with immunoperoxidase conjugated-TPA showed a reticular pattern in the medulla. There is a possibility that the fucosyl residues may be expressed in the Ia antigen as has previously been suggested in other species.
We have recently described that urines from salt-loaded rats contain a potent natriuretic factor acting at the Na-K-Cl cotransport system (CIF: "Cotransport Inhibitory Factor"). Here we investigated the kinetics of the urinary CIF excretion which follows an oral salt-load: (i) in normal rats, relative to that of the atrial natriuretic peptide (ANP) and (ii) in an experimental model of salt-dependent genetic hypertension (Dahl's rats). Thus, Wistar rats were orally loaded with 2% NaCl for 8 days. Urinary CIF excretion was measured by testing the inhibitory potency of urines on bumetanide-sensitive lithium efflux in lithium-loaded human erythrocytes. Plasmatic levels of ANP were measured by radioimmunoassay. Plasma ANP rapidly and transiently increased during the first 24 hs of salt-load, decreasing thereafter down to normal levels in 6-8 days. Conversely, CIF slowly increased after 24 hs up to maximal constant levels after 5 days of salt-loading. Dahl salt-sensitive rats exhibited highly significant increases in urinary CIF excretion with respect to salt-resistant rats. In the basal state (before salt-loading) urinary CIF excretion was 101 +/- 13 vs 17.6 +/- 4.5 units/day in salt-sensitive vs. salt-resistant rats (n = 7 for each group, p < 0.001). This difference was maintained after salt loading (3 380 +/- 990 vs. 456 +/- 159 units/day, p < 0.05 at day 5).(ABSTRACT TRUNCATED AT 250 WORDS)
The authors projected to the Portuguese population the data on prevalence of dementia and Alzheimer's disease obtained respectively by Hofman et al. and Rocca et al through reanalyses of European epidemiological studies conducted or published between 1980 and 1990. The projection relies on the fact that the results of these reanalyses are extensive to all European countries. With this projection which is based on the Portuguese population census of 1991 the numbers of about 92.470 demented patients and about 48.706 Alzheimer's patients are obtained for Portugal. The authors think that, until systematic epidemiological studies of dementia and Alzheimer's disease are available in Portugal, the data now provided are useful for the planning of the care of these patients.
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It was found that 48 hour cultures of Actinobacillus pleuropneumoniae secreted proteases into the medium. Electrophoresis in polyacrylamide gels (10%) copolymerized with porcine gelatin (0.1%), of the 70% (NH4)2SO4 precipitate from the culture supernatants, displayed protease activities of different molecular weights: > 200, 200, 90, 80, 70 and 50 kDa. They had activity over a broad range of pHs (4-8), with an optimal pH of 6-7. All were inhibited by 10 mM EDTA, and reactivated by 10 mM calcium. They were stable at -20 degrees C for more than a month. The proteases also degraded porcine IgA and porcine, human, and bovine hemoglobin, although they appeared to be less active against the hemoglobins. The IgA was totally cleaved in 48 h, using supernatants concentrated with polyvinyl pyrrolidone or the 70% (NH4)2SO4. Extracellular proteases could play a role in virulence.
Gram-negative bacterial sepsis is associated with endotoxemia and a high mortality rate. In previous studies, we demonstrated the therapeutic benefit of an anti-lipopolysaccharide factor isolated from amebocytes of Limulus polyphemus, and of a recombinant version of this protein, termed endotoxin neutralizing protein (ENP), in rabbits challenged with purified lipopolysaccharides. To assess the benefit of ENP in treating a live bacterial infection, we established a rabbit model of Escherichia coli (E. coli) peritonitis and bacteremia with high mortality despite gentamicin treatment. Twenty-four pairs of New Zealand white rabbits were challenged intraperitoneally (IP) with E. coli O18ac K1 in 5% porcine mucin (mean bacteria per dose = 2.5 x 10(8)). The animals were treated with intravenous (i.v.) gentamicin (2.5 mg/kg), and with either ENP (5 mg/kg) or saline i.v. at 1 hr after E. coli challenge. All rabbits were bacteremic 1 hr after challenge (geometric mean 4.1 +/- 1.2 x 10(4) cfu/mL). Peak geometric mean serum endotoxin (2.62 v 10.54 EU/mL, P = .013) and tumor necrosis factor (TNF) (2540 v 6438 TNF units/mL, P = .046) concentrations were lower in ENP-treated animals as compared to control animals. Seven of 24 animals treated with ENP survived 24 hr compared with 4 of 24 controls (Kaplan-Meier analysis, P = .19). However, in the subgroup of 13 paired animals in whom bacteremia was eliminated by gentamicin treatment, 5 of 13 ENP-treated animals survived 24 hr, compared with 1 of 13 controls (Kaplan-Meier analysis, P = .032).(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertrophic pyloric stenosis (HPS) is a common medical emergency in newborns and lactating infants. Ultrasonography (US) is the diagnostic imaging procedure of choice in most centers, leaving the radiological study with barium for those cases in which US is negative and clinical symptoms persist or when other causes of vomiting must be discarded. We report our experience in 67 children (58 male) with suspected HPS. The US findings were consistent with HPS in 45 patients, and the diagnosis was surgically confirmed in all. In the remaining 22 patients with negative US findings, symptoms improved during follow up, with medical treatment. In one patient US was negative for HPS but showed an antral web, that was surgically confirmed. Since there were no false positive or negative results, the specificity and sensitivity of US for HPS diagnosis was 100%. We strongly recommend the use of US in patients with suspected HPS.
BACKGROUND: It has been suggested that vitamin C can modify the composition of lipoproteins in healthy subjects. OBJECTIVE: To determine the possible modification of lipid levels in the presence of vitamin C, and the effect of various doses on lipid levels. DESIGN: This is a sequential open clinical trial, where the same individuals are used as their own controls, and where the same observer at random administers 1 or 2 g of oral vitamin C during a month, followed by a further month without treatment. PATIENTS: 124 healthy volunteers of both sexes, between 17 and 74 years of age, whose lifestyle was not modified during the study. MEASUREMENT: At the beginning of the study a determination was made of lipid levels, risk factors such as age, physical activity, tobacco and alcohol use, weight and arterial pressure; at the end of the first month during vitamin C therapy, and again at the end of the second month without therapy, lipid levels were determined, namely, TG, TC, HDL-C, HDL2-C, HDL3-C, LDL-C, ApoA1, ApoB and Lp(a). RESULTS: After one month of treatment with 2 grams of vitamin C, a significant decrease of ApoB was observed, namely, 5.5% in females and 8% in males (p = 0.019). Vitamin C treatment shows the following differential data: a negative correlation of Lp(a) with HDL3-C, in both sexes; in males, the positive correlation of age with LDL-C and the negative correlation of tobacco with HDL-C disappear, positive correlations appear between physical activity and HDL-C, between tobacco and LDL-C, between weight and ApoB, between SBP and TG, and between DBP and ApoB; in females, the positive correlation between weight and TG, and the negative correlation between weight and HDL-C both disappear, negative correlations appear between physical activity and both TC and ApoB, between weight and HDL3-C, a positive correlation appears between DBP and HDL2-C. Compared to non-drinkers, in males who consume less than 50 grams of alcohol daily, vitamin C produces a significant decrease in DHL3-C, while the significant increase in Lp(a) disappears. CONCLUSIONS: From the results in the follow-up of this group of healthy individuals, it can be deduced that vitamin C produces a decrease in ApoB in both sexes where 2 g are administered daily. When the risk factors are correlated, the results vary substantially, particularly with reference to the sex of the individuals. Women benefit much more than men from vitamin C therapy, especially when physical activity, weight and diastolic blood pressure are considered. Compared to non-drinkers, male drinkers demonstrate a decrease in HDL3-C, and the significant increase in Lp(a) disappears.