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I Alonso

Publications and source records attributed to I Alonso.

At least 19 recordsLinked to original sources
PubMed2006

Some aspects about the structure of the optically isotropic phase in a bent-core liquid crystal: chiral, polar, or steric origin.

We have studied a bent-core liquid crystal where two different optically isotropic phases can be induced by a strong electric field. Depending on the field treatment the phases can present optical rotation or be optically inactive. The switching dynamics of the phases is studied by means of electrooptic and optical second-harmonic generation measurements. It is found that the ground state of the phases is locally antiferroelectric. The structure of the phases is consistent with a disordered version of the kind of structures recently proposed for the smectic blue phase: layered systems with high Gaussian curvature. The origin of the smectic layer distortion is discussed. It is concluded that the direct reason for the curvature of planes is of steric nature.

Journal Article↗
PubMed2003

Effectiveness of low-dose intramuscular anti-VHB immune globulin in the prophylaxis of viral B hepatitis reinfection after liver transplantation: preliminary report.

INTRODUCTION: Prophylaxis using high-dose intravenous anti-HBV immune globulin (HBIG) is effective to prevent reinfection due to hepatitis B virus (HBV) after orthotopic liver transplantation (OLT). However, this treatment is expensive and intravenous administration is difficult during outpatient care. Our aim was to assess the effectiveness of low-dose intramuscular HBIG to prevent HBV reinfection after OLT. PATIENTS: Six patients (all men, mean age 41 years, negative HBV DNA without hepatotropic virus coinfection) were transplanted in our institution due to HBV cirrhosis and included in a prospective noncomparative study. Intramuscular HBIG (2000 IU) was administered during the anhepatic phase of OLT, followed by daily 2000 IU doses for 7 days and then monthly. HBV antibody titers were measured every month. Reinfection was defined as the recurrence of surface HBV antigen in serum after transplantation. RESULTS: After 1 year follow-up, none of the six patients had detectable HBV surface antigen and the liver biopsies were normal in all cases. Using 2000 IU, anti-HBs levels were: 880+/-356 IU/L at 1 month, 191+/-123 at 6 months, and 225+/-49 after 1 year. In all cases anti-HBs titers were above 100 IU/L during the follow-up. CONCLUSIONS: Monthly administration of low-dose (2000 IU) intramuscular HBIG effectively prevents recurrence of HBV infection as well as attains a protective level of anti-HBs antibodies (over 100 IU/L) for at least the first year after transplantation.

Adult↗
PubMed2002

TGF-beta(3)-induced chondroitin sulphate proteoglycan mediates palatal shelf adhesion.

In mammals, the adhesion and fusion of the palatal shelves are essential mechanisms in the development of the secondary palate. Failure of any of these processes leads to the formation of cleft palate. The mechanisms underlying palatal shelf adhesion are poorly understood, although the presence of filopodia on the apical surfaces of the superficial medial edge epithelial (MEE) cells seems to play an important role in the adhesion of the opposing MEE. We demonstrate here the appearance of chondroitin sulphate proteoglycan (CSPG) on the apical surface of MEE cells only immediately prior to contact between the palatal shelves. This apical CSPG has a functional role in palatal shelf adhesion, as either the alteration of CSPG synthesis by beta-D-Xyloside or its specific digestion by chondroitinase AC strikingly alters the in vitro adhesion of palatal shelves. We also demonstrate the absence of this apical CSPG in the clefted palates of transforming growth factor beta 3 (TGF-beta(3)) null mutant mice, and its induction, together with palatal shelf adhesion, when TGF-beta(3) is added to TGF-beta(3) null mutant palatal shelves in culture. When chick palatal shelves (that do not adherein vivo nor express TGF-beta(3), nor CSPG in the MEE) are cultured in vitro, they do not express CSPG and partially adhere, but when TGF-beta(3) is added to the media, they express CSPG and their adhesion increases strikingly. We therefore conclude that the expression of CSPG on the apical surface of MEE cells is a key factor in palatal shelf adhesion and that this expression is regulated by TGF-beta(3).

Animals↗
PubMed2002

Trinucleotide repeats in 202 families with ataxia: a small expanded (CAG)n allele at the SCA17 locus.

BACKGROUND: Ten neurodegenerative disorders characterized by spinocerebellar ataxia (SCA) are known to be caused by trinucleotide repeat (TNR) expansions. However, in some instances the molecular diagnosis is considered indeterminate because of the overlap between normal and affected allele ranges. In addition, the mechanism that generates expanded alleles is not completely understood. OBJECTIVE: To examine the clinical and molecular characteristics of a large group of Portuguese and Brazilian families with ataxia to improve knowledge of the molecular diagnosis of SCA. PATIENTS AND METHODS: We have (1) assessed repeat sizes at all known TNR loci implicated in SCA; (2) determined frequency distributions of normal alleles and expansions; and (3) looked at genotype-phenotype correlations in 202 unrelated Portuguese and Brazilian patients with SCA. Molecular analysis of TNR expansions was performed using polymerase chain reaction amplification. RESULTS: Patients from 110 unrelated families with SCA showed TNR expansions at 1 of the loci studied. Dominantly transmitted cases had (CAG)(n) expansions at the Machado-Joseph disease gene (MJD1) (63%), at SCA2 (3%), the gene for dentatorubropallidoluysian atrophy (DRPLA) (2%), SCA6 (1%), or SCA7 (1%) loci, or (CTG)(n) expansions at the SCA8 (2%) gene, whereas (GAA)(n) expansions in the Freidreich ataxia gene (FRDA) were found in 64% of families with recessive ataxia. Isolated patients also had TNR expansions at the MJD1 (6%), SCA8 (6%), or FRDA (8%) genes; in addition, an expanded allele at the TATA-binding protein gene (TBP), with 43 CAGs, was present in a patient with ataxia and mental deterioration. Associations between frequencies of SCA2 and SCA6 and a frequency of large normal alleles were found in Portuguese and Brazilian individuals, respectively. Interestingly, no association between the frequencies of DRPLA and large normal alleles was found in the Portuguese group. CONCLUSIONS: Our results show that (1) a significant number of isolated cases of ataxia are due to TNR expansions; (2) expanded DRPLA alleles in Portuguese families may have evolved from an ancestral haplotype; and (3) small (CAG)(n) expansions at the TBP gene may cause SCA17.

Adenine↗
PubMed2001

Sulfoxides as stereochemical controllers in intermolecular Heck reactions.

The study of a variety of substituted sulfoxides as chiral auxiliaries in intermolecular Heck reactions of sulfinyldihydrofurans and sulfinylcyclopentenes with different iodoarenes is reported. In the presence of [Pd(OAc)2]/Ag2CO3 and a bidentate phosphine ligand, synthetically useful yields and asymmetric inductions were obtained. By far the best diastereoselectivities were obtained by the use of the palladium-coordinating O-(N,N-dimethylamino)phenylsulfinyl group. By final removal of the chiral auxiliary, these sulfoxide-stereocontrolled asymmetric Heck processes were applied to the enantioselective synthesis of 1-aryl-substituted and 1,3-diaryl-substituted dihydrofurans and cyclopentenes.

Journal Article↗
PubMed2001

A survey of spinocerebellar ataxia in South Brazil - 66 new cases with Machado-Joseph disease, SCA7, SCA8, or unidentified disease-causing mutations.

BACKGROUND: The autosomal dominant spinocerebellar ataxias (SCAs) are a clinical and genetically heterogeneous group of debilitating, neurodegenerative diseases, related to fourteen different loci - SCAs 1, 2, 4, 5, 6, 7, 8, 10, 11,12,13 and 14, Machado-Joseph disease (MJD/SCA 3), and DRPLA. OBJECTIVES: (1) To verify the frequency of SCA1, SCA2, MJD, DRPLA, SCA6, SCA7 and SCA8 in a series of new SCA patients from South Brazil and (2) to compare their molecular and clinical characteristics with other patients previously described. METHODS: Sixty-six cases were included in the present study: 52 were familial and 14 sporadic. Molecular analysis of the trinucleotide repeat loci were performed according to methods in the literature. RESULTS: 92% of families with autosomal dominant inheritance segregated the MJD1 mutation,2% of families segregated the SCA7 mutation and 6% remained undiagnosed. Among 14 isolated cases, one showed the SCA8 mutation. Clinical and molecular findings were similar to those already described in the literature, but revealed (1) one SCA7 patient with eyelid retraction, a sign usually related to MJD; and (2) one sporadic case of SCA8. CONCLUSIONS: The proportion of MJD cases was very high, probably reflecting an Azorean founder effect. The estimated frequency of affected individuals with MJD, in our region, was 1.8 / 100,000, and of SCAs other than MJD, 0.2/100,000.

Adult↗
PubMed2001

Study of the influence of electroconvulsive therapy on the regional cerebral blood flow by HMPAO-SPECT.

STUDY OBJECTIVE: The aim of this preliminary study is to investigate the regional blood flow in response to ECT (electroconvulsive therapy) and to identify any responsive-pattern to the treatment. METHODS STUDY DESIGN: Single longitudinal prospective study of cohorts. SUBJECTS: For this preliminary study ten patients, female sex, mean age 70.8 years with major mood disorder (CID-10 investigation criteria) were studied after signature consent. INTERVENTIONS: The intervention consisted in the administration of bilateral brief pulse ECT three times a week, during 6 to 12 sessions according to the standards of the Psychiatric Department of the Santiago Hospital in Victoria. MEASUREMENT: Clinical evaluation of depression was evaluated by Hamilton Depression Scale, Montgomery and Asberg Scale, Newcastle Scale and regional cerebral blood flow (rCBF) using the HMPAO-SPECT. RESULTS: The pattern of distribution on the regional cerebral flow during the ECT showed changes from the basal pattern in all patients. All patients had a relative increased perfusion of the temporal lobes and basal ganglia. Other changes from the basal study were areas of decreased perfusion of the occipital lobe (6 patients) and parietal lobe (3 patients). CONCLUSIONS: Brain perfusion SPECT study of the patients with major depression shows changes during ECT. Further analysis are needed to understand the relationship between mechanisms of treatment and recovery in affective illness.

Aged↗
PubMed2001

Nonlinear estimation and statistical testing of periods in nonsinusoidal longitudinal time series with unequidistant observations.

The analysis of multiple components is often used to model biological variables that show nonsinusoidal predictable changes of known periods. In general, to anticipate the periods is not easy, and even in cases when we have some a priori information, it is advisable to have a statistical tool to test the chosen periods. In this work, we introduce a statistical procedure to estimate periods of longitudinal series by applying nonlinear regression techniques to the multiple sinusoidal model, as well as to the general linear model. Approximate inferences about the parameters of the model are carried out under the usual hypothesis of normality, independence, and constant variance of the errors. Confidence intervals (CIs) for each individual parameter, as well as for the amplitude-acrophase pair or for any other subgroup of parameters of interest, can be computed. As in the linear analysis of multiple components, it is possible to check the existence of rhythm by means of a zero-amplitude test. The method also allows statistical testing of several hypotheses related to the periods. For example, it is possible to test if the periods are equal to certain values of chronobiologic interest and to check if some components included in the model are harmonically related. On the other hand, when the fitted components have proximal periods, the method allows one to verify if they are modeling the same or different spectral peaks. The method, which was validated by a simulation study for a model of two components and is illustrated by an example of modeling the diastolic blood pressure of two subjects, represents a new step in the development of statistical procedures in chronobiology.

Adult↗
PubMed2001

Circadian rhythm of double (rate-pressure) product in healthy normotensive young subjects.

The double product (DP), systolic blood pressure multiplied by heart rate, is a surrogate measure of myocardial oxygen demand and cardiac workload used increasingly today in medicine. The double product is more strongly correlated with left ventricular mass than the daily blood pressure mean. The purpose of this study was to describe the normative circadian pattern of the double product in healthy normotensive young adults. We studied 125 men and 75 women, 23.0+/-3.3 (mean +/- SD) years of age, without medical history of hypertension and 24h ambulatory systolic/diastolic blood pressure mean consistently below 135/85 mm Hg. Subjects underwent ambulatory blood pressure monitoring at 30-minute intervals for 48 consecutive hours once each season of the year, yielding 930 protocol-correct blood pressure and heart rate time series. Subjects maintained their usual routine of diurnal activity and nocturnal sleep and avoided use of over-the-counter and other medication. Circadian rhythmicity in the double product was established by population multiple-component analysis. The double product rose rapidly from the lowest value, attained 3h before awaking from sleep at night, to a markedly elevated level at the commencement of morning activity. The double product was highest in the afternoon, roughly 7h after the commencement of diurnal activity. In both men and women, the shape of the high-amplitude circadian rhythm in the double product was best described by a complex model composed of three cosine curves having periods of 24h, 12h, and 6h. The 24h mean in the double product of 8092.51+/-42.76 (mean +/- SD) in men was significantly lower than that of 8353.17+/-37.48 in women (P < .001). The circadian double amplitude of the rhythm was statistically significantly greater (P < .001) in men (50% of the 24h mean) than women (44% of the 24h mean). The double product did not differ between seasons in women, but it did in men (P = .017) due to reduced heart rate in summer. The circadian pattern of large amplitude in the double product and its gender differences must be taken into account when using this variable to assess cardiac workload, risk of left ventricular hypertrophy, and efficiency of antihypertensive therapy.

Adult↗
PubMed2001

Small cell carcinoma of the kidney: a case report and review of the literature.

Small cell carcinoma is a malignant tumor composed of small cells with a diffuse growth pattern. It has immunohistochemical and ultrastructural features of both neuroendocrine and epithelial neoplasms. These tumors constitute 10% to 20% of malignant tumors in the lung, which is their most frequent site. They have been described in other extrapulmonary sites, where they are defined using the same criteria as used in the lung. These tumors are rarely found in the genitourinary tract. Fewer than 30 cases have been reported in the kidney. The differential diagnosis mainly includes other small round cell tumors and metastatic small cell lung carcinoma. We present and discuss a primary small cell carcinoma of the kidney (to our knowledge the 9th to be reported in the literature), which we studied with light microscopy, immunohistochemistry, electron microscopy, and, for the first time, flow cytometry.

Aged↗
PubMed2000

Color Doppler sonography in the diagnosis of neonatal intrahepatic portosystemic shunts.

Intrahepatic portosystemic shunts are infrequent in children. We report 3 cases of neonates who presented with jaundice during the first month of life. Color Doppler sonography in the first 2 cases showed direct communication between the right portal and hepatic veins. Both infants were asymptomatic, and the shunts disappeared spontaneously. The third case involved several shunts and an aberrant medial portal vein. This patient developed heart failure and died after surgery. Color Doppler sonography was useful in the diagnosis and follow-up of the shunts in all 3 cases.

Digestive System Abnormalities↗
PubMed2000

High germinal instability of the (CTG)n at the SCA8 locus of both expanded and normal alleles.

The autosomal dominant spinocerebellar ataxias (SCAs) are a group of late-onset, neurodegenerative disorders for which 10 loci have been mapped (SCA1, SCA2, SCA4-SCA8, SCA10, MJD, and DRPLA). The mutant proteins have shown an expanded polyglutamine tract in SCA1, SCA2, MJD/SCA3, SCA6, SCA7, and DRPLA; a glycine-to-arginine substitution was found in SCA6 as well. Recently, an untranslated (CTG)n expansion on chromosome 13q was described as being the cause of SCA8. We have now (1) assessed the repeat size in a group of patients with ataxia and a large number of controls, (2) examined the intergenerational transmission of the repeat, and (3) estimated the instability of repeat size in the sperm of one patient and two healthy controls. Normal SCA8 chromosomes showed an apparently trimodal distribution, with classes of small (15-21 CTGs), intermediate (22-37 CTGs), and large (40-91 CTGs) alleles; large alleles accounted for only0.7% of all normal-size alleles. No expanded alleles (>/=100 CTGs) were found in controls. Expansion of the CTG tract was found in five families with ataxia; expanded alleles (all paternally transmitted) were characterized mostly by repeat-size contraction. There was a high germinal instability of both expanded and normal alleles: in one patient, the expanded allele (152 CTGs) had mostly contraction in size (often into the normal range); in the sperm of two normal controls, contractions were also more frequent, but occasional expansions into the upper limit of the normal size range were also seen. In conclusion, our results show (1) no overlapping between control (15-91) and pathogenic (100-152) alleles and (2) a high instability in spermatogenesis (both for expanded and normal alleles), suggesting a high mutational rate at the SCA8 locus.

Adolescent↗
PubMed2000

Blood pressure patterns in normal pregnancy, gestational hypertension, and preeclampsia.

With the aim to describe the daily pattern of blood pressure during the trimesters of pregnancy in clinically healthy women as well as in pregnant women who developed gestational hypertension or preeclampsia, we analyzed 1494 blood pressure series systematically sampled by ambulatory monitoring for 48 hours every 4 weeks after the first obstetric visit in 124 women with uncomplicated pregnancies, 55 with gestational hypertension, and 23 with a final diagnosis of preeclampsia. The circadian pattern of blood pressure variation for each group and trimester of gestation was established by population multiple-component analysis. A highly statistically significant circadian pattern represented by a linear model that includes components with periods of 24 and 12 hours is demonstrated for systolic and diastolic blood pressure for all groups of pregnant women in all trimesters (P:<0.001 in all cases). The differences in circadian rhythm-adjusted mean between complicated and uncomplicated pregnancies are highly statistically significant in all trimesters (always P:<0.001). There is also a statistically significant difference in circadian amplitude (extent of daily change) of blood pressure between healthy and complicated pregnancies in all trimesters (always P:<0.004). Results further indicate similar circadian characteristics between women who later developed gestational hypertension or preeclampsia in the first trimester of pregnancy. The difference between these 2 groups in circadian mean is statistically significant in the second trimester for systolic (P:=0.022) but not for diastolic blood pressure (P:=0.986). In the third trimester, the difference in circadian mean is highly statistically significant for both variables (P:<0.001). The differences in blood pressure between healthy and complicated pregnancies can be observed as early as in the first trimester of pregnancy. Those highly significant differences are found when both systolic and diastolic blood pressure for women with a later diagnosis of gestational hypertension or preeclampsia are well within the accepted normal physiological range of blood pressure variability. These differing changes in the circadian pattern of blood pressure with advancing gestational age between healthy and complicated pregnancies offer new end points that may lead to an early identification of hypertensive complications in pregnancy as well as to the establishment of prophylactic intervention.

Adolescent↗
PubMed1999

Administration time-dependent effects of aspirin in women at differing risk for preeclampsia.

This study extends previous results on the effects of low-dose aspirin on blood pressure in pregnant women at differing risk of developing hypertension in pregnancy and who received aspirin at different times according to their rest-activity cycle. A double-blind, randomized, placebo-controlled trial was conducted in 240 pregnant women randomly assigned to 1 of 6 groups according to treatment (placebo or aspirin, 100 mg/d, starting at 12 to 16 weeks of gestation) and the time of treatment: on awakening (time 1), 8 hours after awakening (time 2), or before bedtime (time 3). Blood pressure and heart rate for each subject were automatically monitored for 2 days every 4 weeks from the day of recruitment until delivery, as well as at puerperium (6 to 8 weeks after delivery). Subjects were further divided for comparative purposes according to the results of the tolerance-hyperbaric test for early identification of those with a higher risk for developing hypertensive complications in pregnancy. Results indicated that there was no effect of aspirin on blood pressure at time 1 (compared with placebo). A blood pressure reduction was, however, highly statistically significant at time 2 and, to a greater extent, at time 3 (mean reductions of 14.2 and 9.6 mm Hg in 24-hour means for systolic and diastolic blood pressure, respectively, at the time of delivery compared with placebo given at the same time). Effects of aspirin on blood pressure were significantly larger for women with a positive test at the time of recruitment (P<0.001). Differences in blood pressure among pregnant women receiving aspirin at different times in the circadian cycle disappeared at puerperium (P>0.212). There was no effect of aspirin or placebo on heart rate. This study corroborates the statistically significant, time-dependent effect of low-dose aspirin on blood pressure in pregnant women with differing risk of developing hypertensive complications in pregnancy. Although the mechanism involved in the administration-time-dependent responsiveness of blood pressure to aspirin still remains uncertain, the use of doses of aspirin <80 mg/d that do not affect placental thromboxane, initiation of the use of aspirin after 16 weeks' gestation, and the lack of circadian timing for aspirin administration could all explain the lack of positive results in previous clinical trials.

Administration, Oral↗