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Biomedical subjects

A Cruz

Publications and source records attributed to A Cruz.

At least 73 records · Page 4Linked to original sources
PubMed1997

Microvessels of the chick chorioallantoic membrane uniformly restrict albumin extravasation during angiogenesis and endothelial cytodifferentiation.

The present study served to evaluate extravasation of albumin across the microvascular endothelium of the chick chorioallantoic membrane (CAM) during the establishment of endothelial barrier functions (days 4.5 to 6.0), during a rapid phase of normigenesis (day 10), and after initiation of endothelial cytodifferentiation (day 14). CAM preparations in shell-less cultures were evaluated by intravital fluorescence confocal microscopy and videodensitometry after microinjections of chicken serum albumin (CSA) conjugated to Fluorescein isothiocyanate (FITC) (1% in Avian Ringers). At each observed temporal stage, FITC-CSA extravasation from the CAM pre-capillaries, capillaries, and post-capillaries was uniformly negligible. Since the endothelial glycocalyx imparts a net negative luminal charge, impedance of CSA transport by mutual charge repulsion was also evaluated. Accordingly, CAM microvessels were pre-infused with protamine sulfate (100 microliters/ml) to neutralize the negative charge. However, interstitial accumulation of FITC-CSA remained negligible. Thus, the presence of tight junctional clefts and paucity of plasmalemmal vesicles during CAM normigenesis probably serve as the principal morphologic correlates to the observed albumin restriction. Further, the normigenic CAM endothelium presents a more restrictive barrier to macromolecules than that of most angiogenic endothelia.

Allantois↗
PubMed1997

Nitric oxide synthase (NOS) expression in the myenteric plexus of streptozotocin-diabetic rats.

Nitric oxide (NO) is an important inhibitory neurotransmitter in the gut. Alterations in NO mediated responses have been described in diabetic animals. The presence of nitric oxide synthase (NOS) reflects the potential for NO synthesis and is found in neurons in the myenteric plexus. The aim of this study was to determine changes in nitric oxide synthase (NOS) expression in the myenteric plexus of the gastrointestinal tract of diabetic rats at three months of streptozotocin-induced diabetes, compared to age matched controls, using immunohistochemistry. Diabetic animals showed a decrease in NOS expression in the antrum, with 59.1 +/- 7.3% of neurons being positive for NOS in diabetes compared to 81.2 +/- 4.7% in controls (P < 0.05). NOS expression in duodenum, ileum, and colon of diabetic animals was not statistically different from controls. Decreased expression of NOS in antrum may contribute to altered gastric emptying observed in diabetics.

Animals↗
PubMed1997

Expression of estrogen receptors in a normal human breast epithelial cell type with luminal and stem cell characteristics and its neoplastically transformed cell lines.

Although approximately two-thirds of breast cancers are estrogen receptor (ER)-positive, only a small proportion of epithelial cells in the mammary gland express the ER. The origin of the ER-positive breast cancers is unknown. Recently, we have developed a culture method to grow two morphologically and antigenically distinguishable types of normal human breast epithelial cells (HBEC) derived from reduction mammoplasty. In this report, we studied the expression of ER in these two types of cells and their transformed cell lines. The results indicate that Type I HBEC with luminal and stem cell characteristics expressed a variant ER (approximately 48 kd) by Western blot analysis. This variant ER contains a deletion in the DNA binding domain (exon 2) as revealed by RT-PCR analysis. The lack of the DNA-binding domain of the variant ER was also confirmed by the ER-estrogen responsive element binding assay, as well as by the immunofluorescence staining of the ER using anti-ER antibodies which recognize either the C-terminal or N-terminal region. In contrast, Type II HBEC with basal epithelial phenotype are ER-negative. Simian virus 40 (SV40) transformed Type I and Type II HBEC lines also expressed the variant ER. Tumors formed in athymic nude mice by in vitro transformed tumorigenic Type I cell lines, however, expressed a high level of wild type ER which was undetectable in these cells grown in vitro before and after tumor formation. Thus, there appears to be a differential ER mRNA splicing between the in vitro and in vivo mileu.

Adult↗
PubMed1997

Occupational allergy in saffron workers.

Sensitization to the flower of saffron, a plant commonly grown in Spain for commercial purposes, and its clinical significance as an occupational allergen were studied. The prick test and RAST, with saffron pollen, stamen, and pistil extracts, were used to evaluate the cutaneous and specific antibody responses in the studied population. Provocation tests in patients with clinical findings were used to verify the implication of saffron components in these symptoms. Fifty saffron workers were evaluated. Three of them were sensitized to saffron pollen and stamen proteins, giving prick and RAST positive values. One patient presented asthma, showing a positive bronchial provocation test, and two patients rhinoconjunctivitis, showing positive conjunctival provocation tests. Of a general allergic population of 237, 10 patients also presented cutaneous test and IgE positive to saffron. Saffron allergens (from pollen and stamens) were characterized by SDS-PAGE immunoblotting. A relevant allergen of 15.5 kDa with profilinic nature was detected and further purified by high-resolution gel filtration chromatography. No allergenic components were demonstrated in pistils. Cross-reactivity of saffron extracts was evaluated by RAST inhibition with respect to other pollen species commonly causing sensitization in the same area of study. A significant degree of cross-reactivity was demonstrated between saffron and Lolium, Salsola, or Olea. The identification of the protein components involved in the cross-reactions was investigated by blot inhibition.

Adolescent↗
PubMed1997

Prevalence of epilepsy in a migrant population near Quito, Ecuador.

A census, uniform screening questionnaire and simple screening neurologic examination were administered door to door to the 221 residents of Paluguillo, a rural migrant community near Quito, Ecuador. This protocol was pretested to assure a high level of sensitivity for detecting major neurologic diseases in both children and adults. Of the participants, 119 (54%) had responses or findings suggesting the presence of neurologic disease, and, in particular, 53 (24%) had responses suggestive of epilepsy. These individuals were then examined by neurologists using fixed diagnostic criteria. The prevalence ratio for epilepsy was found to be 22.6/1,000. The results of this survey support the conclusion that epilepsy has a higher prevalence in rural areas of socioeconomically deprived countries than it does in industrialized nations.

Adolescent↗
PubMed1996

Determination of the Isotope Shift of the 000 Band of the First Singlet-Singlet Electronic Transition of Cl- and Br-Benzene in a Supersonic Beam

By using resonance-enhanced two-photon ionization in a supersonic beam, photoionization spectra of the 0(0)0 band of the first singlet-singlet electronic transition of 35Cl-, 37Cl-, 79Br-, and 81Br-C6H5 have been obtained at a rotational temperature of 1 K. The ions have been analyzed according to their masses in a time-of-flight mass spectrometer. From the spectra of 35Cl- and 37Cl-C6H5 obtained simultaneously, an isotope shift of 0.14 +/- 0.02 cm-1 has been determined. Similarly, from the spectra of 79Br- and 81Br-C6H5 the isotope shift resulted to be smaller than 0.02 cm-1. The spectra obtained have been interpreted by considering the geometrical structure and symmetry of each molecule, and values for the rotational constants and geometrical parameters in the upper and lower states have been obtained in agreement with the experimental results.

Journal Article↗
PubMed1996

Persistent placenta increta: a complication of conservative management of presumed placenta accreta.

BACKGROUND: Recent reports have advocated conservative management rather than hysterectomy for placenta increta and its related conditions, placenta accreta and percreta. We report an unusual case of placenta increta in which initial conservative therapy for a presumed placenta accreta failed and hysterectomy was performed 6 months postpartum. CASE: A 32-year-old woman, gravida 2, para 2, was referred 5 months after a repeat cesarean delivery and bilateral tubal interruption for evaluation of an intrauterine mass. A presumed placenta accreta noted at delivery had been managed conservatively. Hysterectomy was performed, and pathologic evaluation was consistent with a retained placenta increta. CONCLUSION: Persistent placental tissue is a potential complication of conservative management of an abnormally adherent placenta.

Adult↗
PubMed1996

Fluorescently labeled pulmonary surfactant protein C in spread phospholipid monolayers.

Pulmonary surfactant, a lipid-protein complex, secreted into the fluid lining of lungs prevents alveolar collapse at low lung volumes. Pulmonary surfactant protein C (SP-C), an acylated, hydrophobic, alpha-helical peptide, enhances the surface activity of pulmonary surfactant lipids. Fluorescein-labeled SP-C (F-SP-C) (3, 6, 12 wt%) in dipalmitoylphosphatidylcholine (DPPC), and DPPC:dipalmitoylphosphatidylglycerol (DPPG) [DPPC:DPPG 7:3 mol/mol] in spread monolayers was studied by epifluorescence microscopy. Mass spectometry of F-SP-C indicated that the protein is partially deacylated and labeled with 1 mol fluorescein/1 mol protein. The protein partitioned into the fluid, or liquid expanded, phase. Increasing amounts of F-SP-C in DPPC or DPPC:DPPG monolayers decreased the size and total amounts of the condensed phase at all surface pressures. Calcium (1.6 mM) increased the amount of the condensed phase in monolayers of DPPC:DPPG but not of DPPC alone, and such monolayers were also perturbed by F-SP-C. The study indicates that SP-C perturbs the packing of neutral and anionic phospholipid monolayers even when the latter systems are condensed by calcium, indicating that interactions between SP-C and the lipids are predominantly hydrophobic in nature.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

Spontaneous formation of interfacial lipid-protein monolayers during adsorption from vesicles.

Spread and adsorbed monolayers of lipid-protein mixtures have served as models for biomembranes and pulmonary surfactant, but their similarity was unclear. Epifluorescence microscopy of monolayers spontaneously adsorbed from vesicles of dipalmitoylphosphatidylcholine or dipalmitoylphosphatidylcholine plus surfactant protein C (SP-C) showed gas, liquid expanded, and liquid condensed (LC) domains. The shapes and distribution of LC domains in the adsorbed and solvent-spread monolayers were quite similar. Labeled SP-C adsorbed into the air-water interface in the company of the lipids. In both forms of monolayers, SP-C occupied the fluid phase and reduced the size and amount of the LC domains. The properties suggest that these adsorbed and spread monolayers are analogous to one another.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

[Use of averaged concentration of urea and whole body urea clearance in prescribing the length of a dialysis session].

Urea kinetic-modelling was performed on 109 patients undergoing hemodialysis (518 urea kinetic studies). Then, the theoretic times for a target TAC = 50 mg/dl (TTAC) and a Kt/V = 1 (TKTV) were estimated. The differences and correlations of both times were calculated. Also the correlation of PCR and Kt/V was analyzed in relation to the range of Kt/V. For all cases no differences were found in dialysis session length (TTAC 221.4 +/- 42.6 min.; TKTV 222.9 +/- 48.9 min.). Mean Kt/V was 1.00 +/- 0.15 and mean TAC was 55.2 +/- 13.2. 313 studies (60.4%) have a TAC > 50 mg/dl. For Kt/V < 0.80, 15.6% have a TAC < 50 mg/dl, when Kt/V > 0.80 41.2% of cases have a TAC < 50 mg/dl (p < 0.01). A linear correlation of Kt/V and PCR was found (r = 0.36, p < 0.01). This correlation was stronger for Kt/V < 0.8 (r = 0.54, p < 0.01, n = 47). When TTAC was compared to TKTV a great variability was found: 20.1% have differences lesser than 15 minutes; and this difference was more than 30 minutes in 58.5%. In 107 cases (20.7%) the TTAC produced a Kt/V < 0.8. In all cases a significant (p < 0.01) linear correlation between TKTV and TTAC was found (r = 0.46). TKTV was greater than TTAC for real Kt/V < 1, and lesser than TTAC cuando the effective Kt/V was > 1. It is concluded that in patients treated by dialysis prescription of dialysis session length by TAC or by Kt/V produce rather different times for an unique patient. These differences are related to the PCR, which have a significant correlation with Kt/V. TAC tends toward under value dialysis session length in patients with inadequate dialysis.

Data Interpretation, Statistical↗
PubMed1996

Influence of PAHO publications on scientific production in the health field in Latin America and the Caribbean.

The influence and impact of PAHO publications on scientific production in the field of health in Latin America and the Caribbean was the subject of a study based on a sample of 45 biomedical journals published between 1985 and 1992 in 17 countries of the Region. A total of 8644 works (mostly articles), containing 82,143 citations, were studied. Of these, 3,806 citations were found to refer to works published by PAHO Headquarters in Washington, D.C.-the Boletín de la Oficina Sanitaria Panamericana receiving 1,444 (38% of the total), the English-language Bulletin of PAHO receiving 222 (6%), works in PAHO's Scientific Publications Series receiving 1064 (28%), and works in other PAHO publications receiving 1076 (28%). Overall, PAHO publications appeared to account for a significant share of the citations studied.

Caribbean Region↗
PubMed1995

Conformational flexibility of pulmonary surfactant proteins SP-B and SP-C, studied in aqueous organic solvents.

The structure of hydrophobic pulmonary surfactant-associated proteins SP-B and SP-C have been studied in different acetonitrile (ACN)/water and trifluorethanol (TFE)/water mixtures by circular dichroism and fluorescence spectroscopy to analyze the conformational flexibility of these proteins in response to changes in solvent composition. SP-B presented a very stable conformation in all the assayed ACN/water mixtures and in TFE/water mixtures containing until 70% TFE, showing around 40% alpha-helix. When SP-B was transferred to mixtures containing more than 70% TFE, the percent of alpha-helix in SP-B increased up to 60%. The fluorescence emission spectra of SP-B in the different solvents showed that tryptophan residues are more sensitive to solvent changes than those of tyrosine, reflecting differential effects on different protein microenvironments. The effect of solvent changes on the two tryptophan populations detected by fluorescence spectra was also different. A model for the folding of SP-B dimers, dominated by intra- and intermolecular disulphide bonds, is proposed. Surfactant protein SP-C revealed a secondary structure much more sensitive to solvent composition than SP-B. It had a main alpha-helical conformation in ACN/water solvents which was up to 63% in mixtures containing more than 60% ACN. When the protein was transferred to solvents containing less than 60% ACN, its secondary structure possessed less percent of alpha-helix and an increased percent of beta-structure. On the other hand, SP-C had a main beta-sheet secondary structure in all the assayed TFE/water mixtures, with 30-40% alpha-helix and around 50% beta-structure. The strong dependence of SP-C conformation on the nature of the solvent is interpreted to arise from its high hydrophobicity and the possible occurrence of protein-protein interactions.

Amino Acid Sequence↗
PubMed1995

Hormonal status affects the reactivity of the cerebral vasculature.

OBJECTIVE: We compared the blood velocity and vascular resistance in the central retinal and ophthalmic arteries in healthy nonpregnant, pregnant, and postmenopausal women (before and after estrogen replacement therapy). STUDY DESIGN: Color flow Doppler ultrasonography was used to determine systolic, diastolic, and mean velocity, as well as the resistance index in the central retinal and ophthalmic arteries in 10 nonpregnant women, 10 third-trimester pregnant women, and 10 hypoestrogenic postmenopausal women. The postmenopausal patients were again studied 2 months after starting daily oral therapy with 2 mg of micronized 17 beta-estradiol. RESULTS: Pregnant women had a significantly (p < 0.05) higher diastolic blood velocity (4.2 +/- 0.8 cm/sec) and a lower resistance index (0.56 +/- 0.05) in the central retinal artery, when compared with nonpregnant women (diastolic velocity 2.8 +/- 0.8 cm/sec, resistance index 0.68 +/- 0.1), and hypoestrogenic postmenopausal women (diastolic velocity 2.6 +/- 0.9 cm/sec, resistance index 0.73 +/- 0.08). Significant differences were not seen in the ophthalmic artery. In the postmenopausal patients estradiol therapy was associated with an increase in diastolic velocity (2.6 +/- 0.9 cm/sec vs 4.1 +/- 1.6 cm/sec) and a decrease in the resistance index (0.73 +/- 0.08 vs 0.66 +/- 0.1) in the central retinal artery but not in the ophthalmic artery. CONCLUSIONS: The blood velocity and vascular resistance in the cerebral microcirculation appear to change according to the phases of a woman's reproductive life. This may be related, in part, to estrogen levels, because estradiol vasodilates small-diameter cerebral vessels in hypoestrogenic postmenopausal women.

Adult↗
PubMed1995

Fasting serum insulin in relation to components of the metabolic syndrome in European healthy men: the European Fat Distribution Study.

To investigate the "metabolic" syndrome in different European populations, samples of 38-year-old healthy men were randomly selected from six centers: Gothenburg (Sweden), Warsaw (Poland), Deinze (Belgium), Verona (Italy), Lumiar (Portugal), and Ede (The Netherlands). In total, 515 men were studied. Anthropometric measurements and blood pressure levels were taken by one or two operators in each center after a common operator's training course. Each blood parameter was analyzed in one laboratory. There were significant intercenter differences in mean values for anthropometric parameters, blood pressure, serum lipids (except for low-density lipoprotein [LDL] cholesterol), and fasting insulin. In particular, fasting serum insulin showed the highest values in Sweden and The Netherlands and the lowest values in Italy and Portugal. In pooled men, fasting insulin was strongly related (P < .001) to body mass index (BMI), waist to hip (WHR) and waist to thigh (WTR) circumference ratios, serum lipids (except for LDL cholesterol), and blood pressure. On the contrary, there were relevant differences in the correlation of insulin with serum lipids and blood pressure when the data were evaluated for each center. However, generally both in each center and in all centers together all these correlations disappeared after adjustment for BMI, with the exception of the correlation with serum triglycerides. In pooled men, multiple regression analysis showed an independent association of fasting insulin, BMI, and WHR with serum triglyceride (P < .001). On the contrary, total, LDL, and high-density lipoprotein (HDL) cholesterol and blood pressure values showed independent associations with BMI and/or WHR but not with fasting insulin in multivariate models.2+ off

Adult↗
PubMed1995

Dysrhythmic profile of human immunodeficiency virus infected patients.

We prospectively studied, with 24-h Holter monitoring, 21 consecutive human immunodeficiency virus (HIV) infected patients, at all stages of the infection, in order to assess their dysrhythmic profile. Three (14.3%) patients presented one isolated run of supraventricular tachycardia, with < 10 beats, that was considered clinically irrelevant. No patient presented other clinically relevant supraventricular or ventricular tachy or bradydysrhythmias. One (4.8%) patient presented intermittent Mobitz type I second-degree AV block, two (9.5%) patients paroxistic 2:1 AV block and one (4.8%) patient presented a bifascicular block on the 12-lead ECG that persisted during the ambulatory recording. This study suggests that clinically relevant cardiac tachydysrhythmias are rare in our population of HIV infected patients. On the other hand we found an unexpectedly high incidence of cardiac impulse conduction disturbances.

Adult↗
PubMed1994

Nimodipine in the management of preeclampsia: maternal and fetal effects.

OBJECTIVE: Our purpose was to determine the effects of orally administered nimodipine on selected maternal and fetal parameters in patients with preeclampsia. STUDY DESIGN: Ten consecutive patients were given 30 mg of nimodipine orally every 4 hours from admission until 24 hours after delivery. Maternal and fetal cerebral blood velocity, umbilical artery blood velocity, fetal heart rate variability, maternal blood pressure and heart rate, and transplacental passage of the drug were studied. All 10 patients were delivered within 24 hours of the first dose of nimodipine. RESULTS: There was an acute and significant reduction in the pulsatility index in the smaller diameter maternal cerebral arteries (ophthalmic and central retinal) and in the fetal middle cerebral artery. The umbilical artery systolic/diastolic ratio was also significantly reduced. Maternal blood pressure was controlled without the need for other antihypertensive medication, and although there was an increase in heart rate after administration of the drug, it was well tolerated. Nimodipine reached significant maternal and fetal levels within 2 hours. CONCLUSIONS: Nimodipine is rapidly absorbed after oral administration and has significant maternal and fetal cerebral vasodilator activity. It is an effective, easily administered antihypertensive agent when used in patients with preeclampsia.

Adult↗