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Biomedical subjects

R Cruz

Publications and source records attributed to R Cruz.

At least 37 records · Page 2Linked to original sources
PubMed1999

Atomic force microscopy study of tooth surfaces.

Atomic force microscopy (AFM) was used to study tooth surfaces in order to compare the pattern of particle distribution in the outermost layer of the tooth surfaces. Human teeth and teeth from a rodent (Golden hamster), from a fish (piranha), and from a grazing mollusk (chiton) with distinct feeding habits were analyzed in terms of particle arrangement, packing, and size distribution. Scanning electron microscopy and transmission electron microscopy were used for comparison. It was found that AFM gives high-contrast, high-resolution images and is an important tool as a source of complementary and/or new structural information. All teeth were cleaned and some were etched with acidic solutions before analysis. It was observed that human enamel (permanent teeth) presents particles tightly packed in the outer surface, whereas enamel from the hamster (continuously growing teeth) shows particles of less dense packing. The piranha teeth have a thin cuticle covering the long apatite crystals of the underlying enameloid. This cuticle has a rough surface of particles that have a globular appearance after the brief acidic treatment. The similar appearance of the in vivo naturally etched tooth surface suggests that the pattern of globule distribution may be due to the presence of an organic material. Elemental analysis of this cuticle indicated that calcium, phosphorus, and iron are the main components of the structure while electron microdiffraction of pulverized cuticle particles showed a pattern consistent with hydroxyapatite. The chiton mineralized tooth cusp had a smooth surface in an unabraded region and a very rough structure with the magnetite crystals (already known to make part of the structure) protruding from the surface. It was concluded that the structures analyzed are optimized for efficiency in feeding mechanism and life span of the teeth.

Acids↗
PubMed1999

Letter

Explore the source record for details and available documents.

Journal Article↗
PubMed1999

Comparative study for the identification of myocardial ischemia by contrast ventriculography under the effect of isosorbide mononitrate and by perfusional myocardial scintigraphy in patients with ischemic heart disease.

OBJECTIVE: To evaluate and compare the usefulness of cineventriculographies, before and after nitrate use, to technetium-99m sestamibi scintigraphy for the identification of myocardial ischemia. METHODS: Twenty-six patients were studied at basal conditions and 5 minutes after intravenous administration of isosorbide mononitrate (0.3 mg/kg), to evaluate the performance and regional wall motion of the left ventricle (LV). The results were compared too those obtained with technetium-99m sestamibi scintigraphy. RESULTS: Before nitrate, contrast ventriculography identified 30 normal segments, 62 hypokinetic segments, 28 dyskinetic segments, and 14 akinetic segments. After drug administration, 99 segments were normal, 11 hypokinetic, 11 dyskinetic, and 13 akinetic. Myocardial scintigraphy revealed 110 ischemic segments and 18 fibrotic segments (p < 0.005). After drug administration, the ventriculography showed increase in the velocity of circumferential fiber shortening (p = 0.0142), the ejection fraction (p = 0.0462), decrease in the end-systolic volume (p = 0.0031) and no change in end-diastolic volume. CONCLUSION: Contrast ventriculography using nitrate proved to be similar to perfusional myocardial scintigraphy in the identification of myocardial ischemia.

Female↗
PubMed1999

Are apolipoproteins A and B better than lipoproteins for assessing risk of obstructive coronary heart disease?

OBJECTIVE: To evaluate whether apolipoproteins A-I (Apo A-I) and B (Apo B) have, higher ensitivity (SN), specificity (SP) and positive predictive value (PPV) than lipoproteins (LP), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), and triglycerides (TGL) in assessing the risk of coronary heart disease (CHD). METHODS: This is a transversal case-control study of 241 patients, who were divided into two groups: 1) 145 patients with CHD, and 2) 96 patients without coronary disease. A model of logistic regression to evaluate the relation between the LPs and CHD was developed in which variables with a p-alpha < 0.1 were included. RESULTS: Apo A-I levels were higher in the patients without CHD, (OR 2.08, CI 1.20-3.57). There were no statistical differences between the values of Apo A-I and the remaining lipid fractions (Apo A-I: 67%; Apo B: 100%; PPV: TC = 71%; TGC = 71%; HDL = 71%; LDL = 71%). The costs of the tests in Reais were as follows: Apo A-I: R$ 56.60; Apo B-100: R$ 56.60; TC: R$ 9.94; HDL: R$ 21.30; LDL: R$ 28.40; TGL: R$ 14.20. CONCLUSION: Levels of Apo A-I and Apo B have no advantage over conventional lipoproteins in predicting the risk of CHD, despite the statistical association between Apo A-I and CHD; in addition, their costs are higher than those of the conventional lipoproteins.

Aged↗
PubMed1999

Lack of a relationship between serum ferritin levels and coronary atherosclerosis evaluated by coronary arteriography.

Many clinical and epidemiological studies have demonstrated the relationship between serum ferritin and ischemic heart disease. In the present study we evaluated the relationship between coronary heart disease (CHD) and serum ferritin levels in patients submitted to coronary arteriography. We evaluated 307 patients (210 (68.7%) males; median age: 60 years) who were submitted to coronary angiography, measurement of serum ferritin and identification of clinical events of ischemic heart disease. Serum ferritin is reported as quartiles. Ninety-six patients (31.27%) had normal coronary angiography (group 1) and 211 (68.73%) had coronary heart disease (group 2). Of the patients with CHD, 61 (28.9%) had serum ferritin levels higher than 194 ng/ml (4th quartile), as opposed to only 14 (14.58%) of those without CHD (P = 0.0067). In the 2nd quartile, 39 patients (18.48%) had CHD, while 35 patients (36.46%) had normal coronary arteries (P = 0.00064). Multivariate analysis of the data showed that the difference between groups was not statistically significant (P = 0.33). We conclude that there is no independent relationship between coronary heart disease and increased levels of serum ferritin.

Coronary Angiography↗
PubMed1998

Nerve growth factor improves evoked potentials and long-term potentiation in the dentate gyrus of presenile rats.

Chronic infusion of nerve growth factor (NGF, 1.2 microg/day) for 14 days to presenile rats (17 months at the beginning of treatment) that showed an initial cognitive impairment led to an improved long-term potentiation in the dentate gyrus. Both the relative increase of the slope of the population excitatory postsynaptic potential and that of the population spike were enhanced by NGF pretreatment after long-term potentiation induction at 400 Hz. The treatment was also able to increase the diminished baseline amplitude of the population spike, an effect not seen when the treatment was applied to older animals [Bergado, J., Fernández, C.I., Gómez-Soria, A., González, O., 1997a. Chronic intraventricular infusion with NGF improves LTP in old cognitively-impaired rats. Brain Res. 770, 1-9] stressing the importance of an early start of trophic therapy to achieve better results.

Animals↗
PubMed1998

[Comparison of coronary arteriosclerosis in patients with myocardial infarction and angina pectoris].

PURPOSE: To compare the severity of the coronary heart disease and the presence of coronary risk factors between angina and myocardial infarction (MI) patients. METHODS: We studied 62 patients with MI and 129 with angina through coronary angiography to evaluate occlusion (lesion of 99% or 100%), extent (with a score of 0-5 derived by the number of vessels affected) and severity (3 groups of different stenosis degrees). Two experiment observers blindly interpreted the angiograms. RESULTS: Patients with MI had more occlusions (50% vs 13.2% [p < 0.01]), more severity (79% vs 54.3% with > 90% stenosis [p < 0.02]) and more extent (2.0 vs 0.87; [p < 0.001]), even when controlled for current coronary risk factors and disease duration. Smoking was the only independent risk factor related to MI (p < 0.001). CONCLUSION: Among the studied patients, coronary heart disease extent and severity was greater in the MI group, as well as the prevalence smoking.

Adult↗
PubMed1998

Multi-center clinical evaluation of combination anorganic bovine-derived hydroxyapatite matrix (ABM)/cell binding peptide (P-15) as a bone replacement graft material in human periodontal osseous defects. 6-month results.

A synthetic cell-binding peptide (P-15) combined with anorganic bovine-derived hydroxyapatite bone matrix (ABM) was compared to demineralized freeze-dried bone allograft (DFDBA) and open flap debridement (DEBR) in human periodontal osseous defects in a controlled, monitored, multi-center trial. Following appropriate initial preparation procedures, flap surgery with defect and root debridement was performed. Three osseous defects per patient were treated randomly with one of three procedures after surgical preparation. Appropriate periodontal maintenance schedules were followed, and at 6 to 7 months re-entry flap surgery was performed for documentation and finalization of treatment. Analysis of variation (ANOVA) and t test analyses of patient mean values from 31 patients revealed that the combination ABM/P-15 grafts demonstrated significantly better mean defect fill of 2.8 +/- 1.2 mm (72.3%) versus a mean defect fill of 2.0 +/- 1.4 mm (51.4%) for defects treated with DFDBA (P <0.05) and a mean defect fill of 1.5 +/- 1.3 mm (40.3%) (P <0.05) for defects treated with DEBR. Other hard tissue findings showed similar clinically superior results with the use of ABM/P-15. Relative defect fill results showed 87% positive (50% to 100% defect fill) responses with ABM/P-15, 58% positive responses with DFDBA, and 41% positive responses with DEBR. There were 8 to 9 times more failures (minimal response) with DFDBA and DEBR (26% to 29% frequency) than with ABM/P-15. Soft tissue findings showed no significant differences among treatments except for greater clinical attachment level gain with ABM/P-15 compared to DEBR. These results suggest that the use of the P-15 synthetic cell-binding peptide combined with ABM yields better clinical results than either DFDBA or DEBR. Further studies are needed to determine the relative roles of the ABM and/or the P-15 in these improved results.

Adult↗
PubMed1998

[Obtention and characterization of murine beta-NGF. Application in a model of cerebral aging].

INTRODUCTION: beta-NGF is a basic protein of 118 aminoacids which acts are a trophic factor for sensory and sympathetic neurons of the peripheral nervous system, and on cholinergic neurons of the anterior basal cerebrum. OBJECTIVES: In view of the functional effect of beta-HGF and its possibilities as a therapeutic agent in neurodegenerative disease, including Alzheimer's disease in this study our aim was to obtain, characterize and show the main results of the application of beta-NGFm in a model of cerebral ageing in rats with cognitive disorders. MATERIAL AND METHODS: For the obtention of beta-NGFm we followed Mobley's method as modified by Ebendal and used mouse submaxillary gland as a source of raw material. The characterization studies were carried out by application of seven techniques which allowed physicochemical characterization and demonstration of the biological activity of the product. Application of beta-NGF obtained under these conditions was carried out in a mode of cerebral ageing and the effects of treatment were assessed by conduct studies, measurement of the activity of the enzyme acetyl cholinesterase and study of neural plasticity. CONCLUSIONS: Characterization studies carried out on the beta-NGFm showed that the protein obtained consists of a mixture of molecules of beta-NGFm which are intact at their extreme N-Terminal, and molecules which have lost the octapeptide of the N-terminal position and show some modification increasing hydrophobicity. All these species were recognized immunologically by the specific antibody anti-NGFm and showed biological activity.

Aging↗
PubMed1998

[Short-term effects of septo-hippocampal pathway transsection and cerebrolysin effects on glutathione-related enzymes in the rat brain].

INTRODUCTION: The cholinergic neurones of the basal forebrain play an important part in cognitive activity and axotomy of these neurones leads to their retrograde atrophy. The nootropic drug, Cerebrolysin, can protect these neurones from neurodegeneration induced by axotomy. Oxidative damage to biomolecules often occurs in neurodegenerative processes. OBJECTIVE: To determine whether transection of the septohippocampal bundle (fimbria-fornix, FF) and administration of Cerebrolysin induce alterations in antioxidant mechanisms. MATERIAL AND METHODS: Four groups of rats were studied: Healthy, treated with physiological saline; healthy treated with Cerebrolysin (2.5 ml/kg daily for one week, intraperitoneally); FF-lesioned and pretreated with physiological saline, and with lesions and pretreated with Cerebrolysin. Twenty four hours after the lesion was produced, the activity of the enzymes glutathione S-transferase (GST), glutathione reductase (GRD) and glutathione peroxidase were measured in various cerebral areas. RESULTS: The lesion caused reduced activity of the three enzymes in the hippocampus, and also in the activity of striatal GRD. Pretreatment with Cerebrolysin did not modify the enzymes in FF-lesioned rats, but did reduce the activity of hippocampal GST in healthy rats. CONCLUSIONS: The results show the sensitivity of enzyme of the glutathione system to denervation of the hippocampus, together with a modest effect of Cerebrolysin in this experimental paradigm.

Amino Acids↗
PubMed1997

Interleukin-4 suppression of tumor necrosis factor alpha-stimulated E-selectin gene transcription is mediated by STAT6 antagonism of NF-kappaB.

Interleukin-4 (IL-4), an immunoregulatory cytokine secreted from activated T-helper 2 lymphocytes, eosinophils, and mast cells, stimulates the expression of a number of immune system genes via activation of the transcription factor, STAT6. However, IL-4 can concomitantly suppress the expression of other immune-related gene products, including kappa light chain, FcgammaRI, IL-8, and E-selectin. We demonstrate that IL-4 activates STAT6 in human vascular endothelial cells and that two STAT6 binding sites are present in the promoter of the E-selectin gene. IL-4-induced STAT6 binding does not activate E-selectin transcription but instead suppresses tumor necrosis factor alpha-induced expression of the E-selectin gene. STAT6 was found to compete for binding to a region in the E-selectin gene promoter containing overlapping STAT6 and NF-kappaB binding sites, effectively acting as an antagonist of NF-kappaB binding and transcriptional activation. This novel mechanism for IL-4-mediated inhibition of inflammatory gene expression provides an example of a STAT factor acting as a transcriptional repressor rather than an activator.

DNA↗
PubMed1997

Lesion of nigrostriatal neurons by 6-hydroxydopamine induces changes in rat brain glutathione-S-transferase.

Wistar rats were lesioned into the nigrostriatal pathway with 6-OHDA. The D-amphetamine-induced circling behavior test was performed to evaluated lesion efficiency. Animals that showed more than 620 turns/90 min were named totally lesioned animals (TLA). The group of rats that performed less than 620 turns/90 min were named partially lesioned animals (PLA). The contents of DA and its catabolites in the striata of these groups, and in the same tissue of the untreated animals, were measured. Moreover, the striatal glutathione-S-transferase (GST) specific activity for all groups was tested, and the kinetics parameters for GST purified from the whole brain were evaluated from other three similar groups. The striatal DA depletion on TLA was greater than in PLA. Striatal GST activity showed a significantly bilateral increase in PLA, whereas TLA exhibited only and ipsilateral augment. There were also differences between groups about the kinetic parameters of the purified brain enzyme. The possible role of GST on the interindividual lesion response difference was analyzed.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Evidence for cell surface and internal phospholipase activity in ascidian eggs.

Upon fertilization, ascidian eggs release a cell surface glycosidase used in the block to polyspermy and undergo cortical contractions resulting from increased intracellular calcium levels. The glycosidase is released by fertilization, calcium ionophores or added phospholipase C (PLC) activity. The PLC inhibitor D609 blocks glycosidase release. Intact Ascidia ceratodes eggs cleave 4-methylumbelliferyl-phospho-choline when it is added to seawater. This yields highly fluorescent 4-methylumbelliferone. Authentic phospholipase C but not phospholipase D can cleave this substrate. Thus, the authors believe that cleavage of the substrate is specific for PLC activity. Eggs incubated in the fluorogenic substrate after having been washed and detergent extracted were not fluorescent. Therefore the substrate failed to enter intact cells. Glycosidase release and PLC activity were stimulated by ionomycin. Octylglucoside or Triton X-100 extracts of ascidian eggs had two forms of phospholipase activity as shown by ion affinity chromatography: PL1 eluting at 0.25 mol/L NaCl and PL2 eluting at 0.6 mol/L NaCl. The PL1 appeared to be isolated as a single protein. When surface proteins were labeled with non-penetrating biotin and were subsequently reacted with streptavidin, half of the PLC activity bound. This demonstrates that half the ascidian egg PLC activity is located on the surface of either the egg or follicle cell, and half is located within the egg.

Animals↗
PubMed1996

Identification of signal-induced IkappaB-alpha kinases in human endothelial cells.

Activation of the nuclear transcription factor-kappaB is an early event in endothelial activation. NF-kappaB activation is regulated by the inducible phosphorylation and subsequent degradation of the inhibitory subunit IkappaB-alpha. We identified two discrete kinases of approximately 36 and 41 kDa in the cytoplasm of human umbilical vein endothelial cells that specifically bind to and phosphorylate the IkappaB-alpha subunit. IkappaB-alpha kinase activity is transiently elevated following treatment with either tumor necrosis factor alpha, interleukin-1beta, or bacterial lipopolysaccharides and precedes activation of either mitogen-activated kinase or Jun kinase. Furthermore, activation of the IkappaB-alpha kinases precedes both the appearance of hyperphosphorylated IkappaB-alpha and its subsequent degradation, as well as the translocation of NF-kappaB to the nucleus. Deletion mutagenesis of the IkappaB-alpha polypeptide revealed that these kinases bind in or around the ankyrin repeat domains and phosphorylate residues within the C terminus. These kinases, however, were not identical to casein kinase II and displayed a pharmacologic profile distinct from other known kinases. These kinases may represent components of a signal transduction pathway regulating IkappaB-alpha levels in vascular endothelium.

Ankyrins↗
PubMed1996

E-selectin in focal cerebral ischemia and reperfusion in the rat.

The selectin family of glycoproteins facilitates the early phase of polymorphonuclear leukocyte adhesion to the endothelial cell and, thus, may promote ischemic cell damage. To evaluate E-selectin in the pathogenesis of focal cerebral ischemia and reperfusion injury, we cloned rat E-selectin cDNA and measured the temporal profiles E-selectin mRNA (Northern blot) and protein (immunohistochemistry) during (1 h of ischemia) and after (up to 1 week) transient (2 h) middle cerebral artery (MCA) occlusion in the male Wistar rat. We also tested the effect on these rats of administration of CY-1503, an analog of sialyl Lewis(x) (SLe(x)), on ischemia cell damage. mRNA for E-selectin was first detected in the ischemic hemisphere at 2 h of reperfusion and persisted to 46 h of reperfusion. E-selectin (protein) was localized to microvessels within the ischemic lesion at 0 h of reperfusion and persisted to 70 h of reperfusion. Treatment of the ischemic animals with CY-1503 (50 mg/kg) (n = 8) significantly reduced infarct volume by 42% (p < 0.05) and significantly reduced myeloperoxidase immunoreactive cells in the ischemic lesion by 60% (p < 0.05). These findings provide the first direct evidence for the involvement of E-selectin in transient MCA occlusion in rats and suggest that the E-selectin may facilitate neutrophil adhesion and subsequent cerebral ischemic cell damage.

Amino Acid Sequence↗
PubMed1996

Chronic TPA treatment inhibits expression of proximal tubule-specific properties by LLC-PK1 cells.

Confluent LLC-PK1 cell populations expressed progressively proximal tubule-specific properties, including gamma-glutamyl transpeptidase activity, sodium hexose symport activity, alkaline phosphatase activity, and villin protein. This was paralleled by an increase in villin protein manifested at the single cell level. Chronic treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) inhibited expression of proximal tubule-specific properties at the levels of enzyme activity, protein content, and mRNA content. Inhibition occurred in all cells of the population. TPA treatment induced a decrease in total protein kinase C (PKC)-alpha protein content and a change in subcellular localization from predominantly soluble to predominantly particulate. PKC-epsilon protein content was unchanged by TPA treatment. PKC-epsilon was localized in both soluble and particulate fractions of control cells but was localized predominantly in particulate fractions after TPA treatment. PKC-delta was barely detectable in control cells, but content was markedly increased by TPA. These results suggest that TPA-induced inhibition of expression of proximal tubule-specific properties is mediated through modulation of content and/or subcellular localization of one or more PKC isozymes, likely PKC-alpha.

Alkaline Phosphatase↗
PubMed1995

Sequence and unusual 3' flanking region of the rat tRNA[Ser]Sec gene.

The single rat selenocysteine tRNA (tRNA[Ser]Sec) locus, including flanking sequence, was isolated by molecular cloning and its nucleotide (nt) sequence determined. In addition to the identification of likely regulatory elements 5' of this gene, this analysis also revealed a novel 3' repeat element consisting of three and a half repetitions of a 34-nt unit.

Animals↗