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Biomedical subjects

M Sosa

Publications and source records attributed to M Sosa.

At least 19 recordsLinked to original sources
PubMed2006

Inhaled steroids do not decrease bone mineral density but increase risk of fractures: data from the GIUMO Study Group.

Although the negative effect of systemic steroids on bone is well documented, there is not clear evidence about possible adverse effects of inhaled steroids on bone metabolism and fractures. A cross-sectional study was performed on 105 women suffering from bronchial asthma treated with inhaled steroids and 133 controls. Bone mineral density (BMD) was measured by quantitative ultrasonography (QUS) at the calcaneus and by dual X-ray absorptiometry (DXA), at both the lumbar spine and proximal femur. Patients suffering from bronchial asthma showed no statistically significant changes in BMD as measured by DXA or QUS, compared with controls. A higher prevalence of fractures was found in the group of women with bronchial asthma, with an age-adjusted odds ratio of 2.79 (95% CI: 1.19-6.54). Inhaled steroids do not appear to decrease BMD, but are associated with an increased risk of fracture in women.

Absorptiometry, Photon↗
PubMed2005

Search for exotic baryons in 800 GeV pp-->pXi+/-piX reactions.

We report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to Xi-pi-, Xi-pi+, Xi+pi-, and Xi+pi+. The only resonances observed are the well known Xi0(1530) and Xi0(1530). No evidence is found for the states near 1862 MeV, previously reported by NA49 [Phys. Rev. Lett. 92, 042003 (2003)]. At the 95% confidence level, we find the upper limit for the production of a Gaussian enhancement with sigma=7.6 MeV in the Xi-pi- effective mass spectrum to be 0.3% of the number of observed Xi0(1530)-->Xi-pi+. We find similarly restrictive upper limits for an enhancement at 1862 MeV in the Xi-pi+, Xi+pi-, and Xi+pi+ mass spectra.

Journal Article↗
PubMed2005

Magnetic field influence on electrical properties of human blood measured by impedance spectroscopy.

The impedance spectroscopy technique (IST) was used for studying the effect of a 0.5 T magnetic field on the electrical properties of whole human blood. A Solartron SI 1260 spectrometer was used to measure the impedance spectra of magnetic field exposed blood samples compared to non-exposed samples. An equivalent electrical circuit model, consisting in a resistance Rs in series with a parallel circuit formed by a constant phase element (CPE) and another resistance Rp, is proposed to fit the data in both cases. The experiment used 3 ml human blood samples from 160 healthy donors. A Wilcoxon matched pairs statistical test was applied to the data. The data analysis seems to show a statistically significant increase of the values of resistance Rp (Z = 5.06, P < 0.001) and capacitance CT (Z = 3.32, P < 0.001) of the blood exposed to magnetic field, by approximately 10.4% and 1.9%, respectively.

Adolescent↗
PubMed2005

Spatiotemporal evaluation of human colon motility using three-axis fluxgates and magnetic markers.

An alternative method to study the mechanical activity of the human colon in fasting and postprandial states is presented. The method is based on measurements of the magnetic fields produced by a magnetic marker, a small cylindrical NdBFe magnet, when it was ingested by the subjects. A portable magnetic probe, consisting of two digital three-axis fluxgate magnetometers, arranged in a first-order electronic gradiometer, was implemented for this research. Measurements were taken in 16 healthy male subjects. Contractile activity frequency measurements were taken along the colon length, including the ascending, transverse and descending sections, as well as the rectal sigmoidal section. Values for the contractile activity frequency of 2-5 cycles min(-1) were measured. The set-up is simple, low-cost and suitable for use in an unshielded environment.

Adult↗
PubMed2005

Postmenopausal women with Colles' fracture have bone mineral density values similar to those of controls when measured with calcaneus quantitative ultrasound.

BACKGROUND: It is a matter of controversy whether or not Colles' fracture is an osteoporotic fracture. Indeed, the usefulness of quantitative ultrasound in distinguishing Colles' fracture from normal fractures is also unclear. METHODS: A cross-sectional case-control study was done on 469 postmenopausal Spanish women, 121 with Colles' fracture and 348 controls. Assessment of risk factors for osteoporosis and measurement of calcaneus quantitative ultrasound were carried out using a Sahara, Hologic device. RESULTS: Patients with Colles' fracture had BUA, SOS, and QUI values that were similar to those of controls, and no statistically significant differences were found. We estimated ROC curves for SOS and a score based on a linear combination of height and SOS (SH-Score). The areas under both curves were 0.56 and 0.61, respectively, which was statistically significant. To obtain 5% false-negative and 10% false-positive figures, the T-score cut-off for SOS was -2.45 and -0.045, respectively. Of these, only 9.2% were classified as high risk and 11% as low risk with 79.8% undetermined. CONCLUSIONS: Patients with Colles' fracture had BUA, SOS, and QUI values that were similar to those of controls. Nevertheless, ROC curves calculated by a combination of height and SOS showed that quantitative calcaneus ultrasound may be a useful tool for identifying postmenopausal women with Colles' fracture. These results indicate that measuring bone mineral density with ultrasound only captures limited aspects of the pathophysiology of Colles' fractures.

Journal Article↗
PubMed2004

Euterpe Olerácea (Açaí) as an alternative oral contrast agent in MRI of the gastrointestinal system: preliminary results.

Using contrast agents is a common practice in medical imaging protocols. Paramagnetic properties of certain compounds present in contrast agents can affect magnetic resonance imaging (MRI) signals. For abdominal applications, they are usually injected, but may also be administered orally. However, their use as a routine technique is limited, mainly due to the lack of appropriate oral contrast agents. We herein present the preliminary characterization and results for implementation of Euterpe Olerácea (popularly named Açaí) as a possible clinical oral contrast agent for MRI of the gastrointestinal tract. The pulp of Açaí, a fruit from the Amazon area, presented an increase in T(1)-weighted MRI signal, equivalent to that of gadolinium-diethyltriamine pentaacetic acid, and a decrease in T(2)-weighted images. We looked for intrinsic properties that could be responsible for the T(1) signal enhancement and T(2) opacification. Atomic absorption spectra revealed the presence of Fe, Mn and Cu ions in Açai. The presence of such ions contribute to the susceptometric value found of chi = -4.83 x 10(-6). This finding assents with the hypothesis that image contrast changes were due to the presence of paramagnetic material. The first measurements in vivo demonstrate a clear increase of contrast, in T(1)-weighted images, due to the presence of Açaí. Consistently, the opacification in a T(2)-weighted acquisition was evident, revealing a good contrast on bowel walls of gastric tissues.

Administration, Oral↗
PubMed2004

Gastric activity studies using a magnetic tracer.

A magnetic pulse generator has been set up in order to study gastric activity. Two coils 1.05 m in diameter, arranged in a Helmholtz configuration, were used. The system generated magnetic field pulses higher than 15 mT, of duration 17.3+/-1.2 ms. Measurements were performed in 11 male volunteers, with average age 29.3+/-6.4 years and body mass index 26.0+/-4.8 kg m(-2). Magnetite (Fe3O4) particles with diameters from 75 to 125 microm were used as magnetic tracers, which were mixed in 250 ml of yogurt in concentrations from 2 to 5 g. Signals were registered by using a high speed 3 axis fluxgate digital magnetometer and processed to determine the relaxation of the magnetic tracers by fitting a first-order exponential function to the data, a mean relaxation constant K = 116+/-40 s(-1) was obtained. Also, an average gastric peristaltic frequency was measured; a value of 3.2+/-0.3 cpm was determined.

Adult↗
PubMed2003

External beam radiotherapy as definitive treatment for prostate cancer.

External beam radiotherapy (EBRT) planning and delivery has dramatically changed in the last 2 decades allowing dose escalation to the prostate while maintaining the same risk of complications. EBRT plays a major role in the treatment of localized (T1-2) and locally advanced (T3-4) prostate cancer. In this review we will focus on some current issues associated with the "modern" use of EBRT such as what to expect from EBRT in terms of tumor control and side effects, what is the role of biopsy and surgery after EBRT, what is the role of androgen deprivation (AD), and how EBRT compares to brachytherapy.

Androgen Antagonists↗
PubMed2002

Lambda(0) polarization in 800-GeV/cpp --> p(f)(Lambda0K+).

We report results from a study of Lambda(0) polarization in the exclusive reaction pp --> p(f)(Lambda0K+) at 800-GeV/c. We observe a dependence of the polarization on the Lambda0K+ invariant mass with large (+71%) positive polarization at small mass (1.63-GeV/c(2)) and large (-43%) negative polarization at large mass (2.75-GeV/c(2)). This observation confirms the result of the CERN ISR R608 experiment and extends the range over which the effect is observed. The strong dependence of the polarization on the Lambda0K+ invariant mass suggests that the origin of the polarization is closely related to the production dynamics of the diffractively produced Lambda0K+ system.

Journal Article↗
PubMed2002

Quantitative ultrasound calcaneus measurements: normative data and precision in the spanish population.

Quantitative ultrasound (QUS) assessment at the calcaneus has been found to be a safe and reliable method for evaluating skeletal status. In this study we have determined the normative QUS data in the Spanish population for the Sahara Clinical Sonometer (Hologic). Broadband ultrasound attenuation (BUA), speed of sound (SOS), quantitative ultrasound index (QUI) and estimated bone mineral density (BMD) were determined. We also studied the precision in vivo and in vitro. The short-term in vivo precision (CV) was 4.88% for BUA, 0.36% for SOS, 3.45% for QUI and 4.15% for BMD, while in vitro precision was 0.40% for SOS and 2.67% for BUA. Our results are comparable to reference population data previously published in other countries and may serve as reference normative data for both genders in Spain.

Adolescent↗
PubMed2002

In vivo measurement of human skin absorption of topically applied substances by a photoacoustic technique.

A photoacoustic technique is used for studying topically applied substance absorption in human skin. The proposed method utilizes a double-chamber PA cell. The absorption determination was obtained through the measurement of the thermal effusivity of the binary system substance-skin. The theoretical model assumes that the effective thermal effusivity of the binary system corresponds to that of a two-phase system. Experimental applications of the method employed different substances of topical application in different parts of the body of a volunteer. The method is demonstrated to be an easily used non-invasive technique for dermatology research. The relative concentrations as a function of time of substances such as ketoconazol and sunscreen were determined by fitting a sigmoidal function to the data, while an exponential function corresponds to the best fit for the set of data for nitrofurazona, vaseline and vaporub. The time constants associated with the rates of absorption, were found to vary in the range between 10 and 58 min, depending on the substance and the part of the body.

Acoustics↗
PubMed2002

Effect of two forms of alendronate administration upon bone mass after two years of treatment.

The efficacy of alendronate in slowing the loss of bone mass, or even in increasing it, in osteoporotic patients and thus reducing the risk of new fractures has been described. Nevertheless, the way of taking this drug, together with its side effects, sometimes produces withdrawals. In this study, we analyzed if an alternative way of taking the alendronate improves the follow-up of the treatment and if it had the same effect on bone mineral metabolism than the traditional way of prescription. An open, intention-to-treat study, with follow-up of 2 yr was conducted. Eighty women suffering from postmenopausal osteoporosis were included in the study. They were classified in a random manner into two groups, each one of them received 10 mg/d alendronate, together with 1.2 g of calcium and 800 IU of Vitamin D3. Group I received the drug fasting, before breakfast, as usually prescribed and group II received the alendronate fasting, at noon, before lunch. Biochemical markers of bone remodeling were determined. Total alkaline phosphatase, osteocalcin, tartrate-resistant acid phosphatase, urine calcium/creatinine ratio, crosslinked N-telopeptides of type I collagen/creatinine ratio, serum calcium, and parathyroid hormone were also determined, and a lateral dorsolumbar radiography of the spine was performed. Bone mineral density was determined in the lumbar spine by dual-energy X-ray absorptiometry and quantitative computed tomography and by dual-energy X-ray absorptiometry in the proximal femur. Both groups showed an increase in bone mineral density in the lumbar spine and in the proximal femur, which was statistically significant after 1 yr of treatment in the range between 1.5% and 4.3%, depending on the anatomical localization where bone mineral density was measured. There was also an important decrease in the biochemical markers of bone remodeling, between 5.6% and 42.5%, depending on the biochemical marker; the decrease of amino-terminal telopetide during the first year was more important. The group that received alendronate in the morning reported a significantly higher number of withdrawals than the group that received the drug at noon. The alternative administration of 10 mg alendronate at noon had the same effect on bone mineral metabolism than its traditional administration in the morning, but the rate of withdrawals was significantly lower.

Absorptiometry, Photon↗
PubMed2001

Diffractively produced charm final states in 800-GeV/c pp collisions.

We report the first observation of diffractively produced open charm in 800-GeV/c pp collisions of the type pp-->pD*X. We measure cross sections of sigma(diff)(D*+) = (0.185+/-0.044+/-0.054) (mu)b and sigma(diff)(D(*-)) = (0.174+/-0.034+/-0.029) (mu)b. Our measurements are based on 4.3x10(9) events recorded by FNAL E690 in the fixed-target run of 1991. We compare our results with previous fixed-target charm experiments.

Journal Article↗
PubMed2001

Transient increase in rab 3A and synaptobrevin immunoreactivity after mild hypoxia in neonatal rats.

1. In the present work we describe the short term effects of mild neonatal hypoxia on the synapse as assessed by the immunoreactivity (IR) of two synaptic proteins: rab 3A and synaptobrevin (VAMP). 2. Using the sensitive methodology of immunoblotting, we measured rab 3A and VAMP-IR in homogenates from the cerebral cortex, hippocampus, and corpus striatum of control (breathing room air) and hypoxiated (breathing 95.5% N2-6.5% O2 for 70 min) 4-day-old rats at 1, 2, and 6 h after the end of the hypoxia. Immunostaining with examination by light microscopy was performed using the synaptic protein-specific antibodies on fixed brain sections from animals belonging to the same litter and submitted to hypoxia. 3. A transient increase of VAMP-IR was observed in the hippocampus and corpus striatum, and for rab 3A in the striatum, 1 h after initiating reoxygenation. At the following time points the values returned to control levels. This effect was less clearly observed in the immunostained sections. 4. Mild hypoxia has an effect on sensitive brain regions, eliciting an increase in the IR of at least two proteins involved in the synaptic vesicle cycle. The transient nature of this effect possibly indicates the activation of endogenous neuroprotective mechanisms.

Animals↗
PubMed2000

The distribution of two different vitamin D receptor polymorphisms (BsmI and start codon) in primary hyperparathyroidism.

INTRODUCTION: The bb genotype of the BsmI polymorphism of the vitamin D receptor (VDR) is more common in primary hyperparathyroidism (HPT) than in the general population in Swedish and German women. However, little is known about the association of HPT with the start codon polymorphism of the VDR (defined by FokI). OBJECTIVE: To study the distribution of the VDR genotypes in a group of women with HPT compared with a control group. The bone mineral density (BMD) of different genotypes was also investigated. METHODS: VDR alleles were typed by polymerase chain reaction (PCR) assay around the polymorphic BsmI or FokI restriction sites in 67 control women (48.5 +/- 10 years) and 53 women with HPT (61.4 +/- 11 years). They were all Caucasian and born in the Canary Islands. Lumbar and proximal femur BMDs were measured by dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT). RESULTS: The 'bb' genotype was equally frequent in controls and HPT subjects (46.3 and 45.3%, respectively). There was a trend towards a lower prevalence of the FF genotype amongst women with HPT as compared with controls (41.5 vs. 57.1%; P = 0.09). BMD was lower in patients with HPT compared with controls in the lumbar spine and the proximal femur. CONCLUSIONS: The association of the BsmI polymorphism of the VDR gene with HPT is not applicable to all geographical areas. In Canarian postmenopausal women suffering from HPT, VDR genotype distribution is similar to that found in controls. A possible association of HPT with the FokI polymorphism deserves further investigation.

Aged↗