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2.
J Endocrinol Invest ; 47(6): 1505-1511, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38129742

RESUMEN

PURPOSE: Serum calcium/phosphate ratio (Ca/P) has been recently proposed as an additional tool to identify primary hyperparathyroidism (PHPT), especially in patients with subclinical presentation, with a proposed cut-off of 3.3 when both values are expressed in mg/dL. No data are available on the relationship between Ca/P and the clinical presentation of PHPT. We thus evaluated this relationship in a large, single-center, unselected series. METHODS: 515 consecutive PHPT patients (mean age 65 ± 13.15 years, 77.1% females) were retrospectively evaluated at diagnosis. RESULTS: Mean Ca/P was 4.54 ± 1.5 (range 2.36-13.9), being higher than 3.3 in 88.5% of patients. Ca/P was significantly higher in (1) males, (2) symptomatic PHPT, (3) patients with 25-hydroxy vitamin D levels lower than 20 µg/L, (4) patients with osteitis fibrosa cystica, (5) patients with T score < - 2.5 at the radial site. In a multivariate regression analysis, Ca/P resulted significantly associated with PTH levels. After the exclusion of 57 patients with asymptomatic PHPT (aPHPT) patients and serum Ca higher than 1 mg/dL above the upper limit of normal range, no differences were found in Ca/P between aPHPT meeting or not surgical criteria. CONCLUSIONS: In PHPT Ca/P ratio is associated with increased biochemical and clinical severity of disease and represents a direct indicator of clinical bone damage. However, it does not seem an additional tool to identify aPHPT patients reaching surgical indication.


Asunto(s)
Calcio , Hiperparatiroidismo Primario , Fosfatos , Humanos , Hiperparatiroidismo Primario/sangre , Hiperparatiroidismo Primario/diagnóstico , Hiperparatiroidismo Primario/cirugía , Femenino , Masculino , Anciano , Calcio/sangre , Estudios Retrospectivos , Persona de Mediana Edad , Fosfatos/sangre , Biomarcadores/sangre , Enfermedades Asintomáticas/terapia , Hormona Paratiroidea/sangre
3.
J Math Biol ; 87(5): 67, 2023 10 08.
Artículo en Inglés | MEDLINE | ID: mdl-37805974

RESUMEN

This work is devoted to introduce and study two quasispecies nonlinear ODE systems that model the behavior of tumor cell populations organized in different states. In the first model, replicative, senescent, extended lifespan, immortal and tumor cells are considered, while the second also includes immune cells. We fit the parameters regulating the transmission between states in order to approximate the outcomes of the models to a real progressive tumor invasion. After that, we study the identifiability of the fitted parameters, by using two sensitivity analysis methods. Then, we show that an adequate reduced fitting process (only accounting to the most identifiable parameters) gives similar results but saving computational cost. Three different therapies are introduced in the models to shrink (progressively in time) the tumor, while the replicative and senescent cells invade. Each therapy is identified to a dimensionless parameter. Then, we make a fitting process of the therapies' parameters, in various scenarios depending on the initial tumor according to the time when the therapies started. We conclude that, although the optimal combination of therapies depends on the size of initial tumor, the most efficient therapy is the reinforcement of the immune system. Finally, an identifiability analysis allows us to detect a limitation in the therapy outcomes. In fact, perturbing the optimal combination of therapies under an appropriate therapeutic vector produces virtually the same results.


Asunto(s)
Modelos Biológicos , Modelos Teóricos , Sistema Inmunológico
4.
J Endocrinol Invest ; 41(11): 1339-1348, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-29616419

RESUMEN

PURPOSE: Evaluation of the phenotype of primary hyperparathyroidism (PHPT), adherence to International Guidelines for parathyroidectomy (PTx), and rate of surgical cure. METHOD: From January 2014-January 2016, we performed a prospective, multicenter study in patients with newly diagnosed PHPT. Biochemical and instrumental data were collected at baseline and during 1-year follow-up. RESULTS: Over the first year we enrolled 604 patients (age 61 ± 14 years), mostly women (83%), referred for further evaluation and treatment advice. Five hundred sixty-six patients had sporadic PHPT (93.7%, age 63 ± 13  years), the remaining 38 (6.3%, age 41 ± 17  years) had familial PHPT. The majority of patients (59%) were asymptomatic. Surgery was advised in 281 (46.5%). Follow-up data were available in 345 patients. Eighty-seven of 158 (55.1%) symptomatic patients underwent PTx. Sixty-five (53.7%) of 121 asymptomatic patients with at least one criterion for surgery underwent PTx and 56 (46.3%) were followed without surgery. Negative parathyroid imaging studies predicted a conservative approach [symptomatic PHPT: OR 18.0 (95% CI 4.2-81.0) P < 0.001; asymptomatic PHPT: OR 10.8, (95% CI 3.1-37.15) P < 0.001). PTx was also performed in 16 of 66 (25.7%) asymptomatic patients without surgical criteria. Young age, serum calcium concentration, 24 h urinary calcium, positive parathyroid imaging (either ultrasound or MIBI scan positive in 75% vs. 16.7%, P = 0.001) were predictors of parathyroid surgery. Almost all (94%) of patients were cured by PTx. CONCLUSIONS: Italian endocrinologists do not follow guidelines for the management of PHPT. Negative parathyroid imaging studies are strong predictors of a non-surgical approach. PTx is successful in almost all patients.


Asunto(s)
Calcio/sangre , Hiperparatiroidismo Primario/diagnóstico , Glándulas Paratiroides/diagnóstico por imagen , Hormona Paratiroidea/sangre , Anciano , Femenino , Estudios de Seguimiento , Humanos , Hiperparatiroidismo Primario/sangre , Hiperparatiroidismo Primario/cirugía , Italia , Masculino , Persona de Mediana Edad , Glándulas Paratiroides/cirugía , Paratiroidectomía , Estudios Prospectivos , Ultrasonografía
5.
Clin Radiol ; 71(8): 722-8, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27207375

RESUMEN

Computed tomography coronary angiography is increasingly used in imaging departments in the investigation of patients with chest pain and suspected coronary artery disease. Due to the routine use of heart rate controlling medication and the potential for very high radiation doses during these scans, there is a need for guidance on best practice for departments performing this examination, so the patient can be assured of a good quality scan and outcome in a safe environment. This article is a summary of the document on 'Standards of practice of computed tomography coronary angiography (CTCA) in adult patients' published by the Royal College of Radiologists (RCR) in December 2014.


Asunto(s)
Angiografía por Tomografía Computarizada/normas , Angiografía Coronaria/normas , Seguridad del Paciente/normas , Guías de Práctica Clínica como Asunto , Protección Radiológica/normas , Radiología/normas , Cardiología/normas , Humanos , Exposición a la Radiación/prevención & control , Exposición a la Radiación/normas , Reino Unido
6.
Clin Radiol ; 71(8): 729-38, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26945872

RESUMEN

Cardiovascular computed tomography (CCT) is a cutting-edge imaging technique providing important, non-invasive, diagnostic information. Concerns exist regarding radiation exposure to patient populations, but achieving optimal image quality at the lowest doses can be challenging. This guide provides practical advice about how quality can be assured in any CCT unit or radiology department. Illustrated by real-world vignettes and data analysis from our own experience, we highlight a multidisciplinary team approach to each stage of the patient journey, the effectiveness of regular dose audit overseen by a CT optimisation group, and the importance of underused systolic scanning techniques, in order to drive significant dose reduction without loss of image quality or clinical confidence.


Asunto(s)
Angiografía por Tomografía Computarizada/normas , Angiografía Coronaria/normas , Seguridad del Paciente/normas , Garantía de la Calidad de Atención de Salud/normas , Protección Radiológica/normas , Radiología/normas , Cardiología/normas , Humanos , Guías de Práctica Clínica como Asunto , Exposición a la Radiación/prevención & control , Exposición a la Radiación/normas , Reino Unido
7.
Oncogene ; 35(25): 3324-34, 2016 06 23.
Artículo en Inglés | MEDLINE | ID: mdl-26455320

RESUMEN

Suppression of detachment-induced cell death, known as anoikis, is an essential step for cancer metastasis to occur. We report here that expression of KLF12, a member of the Kruppel-like family of transcription factors, is downregulated in lung cancer cell lines that have been selected to grow in the absence of cell adhesion. Knockdown of KLF12 in parental cells results in decreased apoptosis following cell detachment from matrix. KLF12 regulates anoikis by promoting the cell cycle transition through S phase and therefore cell proliferation. Reduced expression levels of KLF12 results in increased ability of lung cancer cells to form tumours in vivo and is associated with poorer survival in lung cancer patients. We therefore identify KLF12 as a novel metastasis-suppressor gene whose loss of function is associated with anoikis resistance through control of the cell cycle.


Asunto(s)
Anoicis/genética , Regulación Neoplásica de la Expresión Génica , Factores de Transcripción de Tipo Kruppel/genética , Neoplasias Pulmonares/genética , Células A549 , Animales , Ciclo Celular/genética , Línea Celular Tumoral , Proliferación Celular/genética , Regulación hacia Abajo , Citometría de Flujo , Humanos , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patología , Ratones Endogámicos NOD , Ratones Noqueados , Ratones SCID , Metástasis de la Neoplasia , Interferencia de ARN , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Supervivencia , Trasplante Heterólogo , Proteínas Supresoras de Tumor/genética
8.
J Endocrinol Invest ; 39(3): 349-54, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26620949

RESUMEN

BACKGROUND: Mild primary hyperparathyroidism (PHPT) was recently clearly defined for the first time. Our study was thus aimed to pinpoint proportion and clinical characteristics of this kind of patients. DESIGN AND PATIENTS: We retrospectively evaluated our series of 360 consecutive patients with PHPT, selecting those with all features allowing a correct classification (serum total and ionized calcium, phosphate, creatinine, PTH, 25OHD, urinary calcium, renal and neck ultrasound, MIBI scintiscan, and DEXA at lumbar spine, femoral neck, and distal third of radius). Patients were defined asymptomatic (aPHPT) when bone or kidney was not involved and no hypercalcemic symptom occurred; mild PHPT was defined as aPHPT not meeting updated surgical criteria. RESULTS: Seventy-five patients among 172 classified as aPHPT had all available data required for surgical evaluation and could be evaluated. Sixty/75 met surgical criteria and the remaining 15 were classified as mild. Mild PHPT patients had lower total and ionized calcium, urinary calcium, and PTH levels than aPHPT meeting surgical criteria, while vitamin D levels and BMD were similar. CONCLUSIONS: Mild PHPT strictly defined according to the last consensus represents a small subgroup with a less active form of the disease.


Asunto(s)
Hiperparatiroidismo Primario/epidemiología , Hiperparatiroidismo Primario/patología , Consenso , Femenino , Estudios de Seguimiento , Humanos , Italia/epidemiología , Masculino , Persona de Mediana Edad , Prevalencia , Pronóstico , Estudios Retrospectivos
9.
J Endocrinol Invest ; 38(12): 1373-81, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26486135

RESUMEN

BACKGROUND: Transpeople often look for sex reassignment surgery (SRS) to improve their quality of life (QoL). The hormonal therapy has many positive effects before and after SRS. There are no studies about correlation between hormonal status and QoL after SRS. AIM: To gather information on QoL, quality of sexual life and body image in transpeople at least 2 years after SRS,to compare these results with a control group and to evaluate the relations between the chosen items and hormonal status. SUBJECTS AND METHODS: Data from 60 transsexuals and from 60 healthy matched controls were collected. Testosterone,estradiol, LH and World Health Organization Quality of Life (WHOQOL-100) self-reported questionnaire were evaluated. Student's t test was applied to compare transsexuals and controls. Multiple regression model was applied to evaluate WHOQOL's chosen items and LH. RESULTS: The QoL and the quality of body image scores intranspeople were not statistically different from the matched control groups' ones. In the sexual life subscale,transwomen's scores were similar to biological women's ones, whereas transmen's scores were statistically lower than biological men's ones (P = 0.003). The quality of sexual life scored statistically lower in transmen than intranswomen (P = 0.048). A significant inverse relationship between LH and body image and between LH and quality of sexual life was found. CONCLUSIONS: This study highlights general satisfaction after SRS. In particular, transpeople's QoL turns out to be similar to Italian matched controls. LH resulted inversely correlated to body image and sexual life scores.


Asunto(s)
Imagen Corporal/psicología , Estradiol/sangre , Hormona Luteinizante/sangre , Calidad de Vida/psicología , Cirugía de Reasignación de Sexo , Testosterona/sangre , Transexualidad , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Conducta Sexual/psicología , Transexualidad/sangre , Transexualidad/psicología , Transexualidad/cirugía
10.
Artículo en Inglés | MEDLINE | ID: mdl-25859391

RESUMEN

UNLABELLED: We report the association of primary hyperparathyroidism (PHPT) and Klinefelter's syndrome (KS) in a 22-year-old male complaining of worsening fatigue. PHPT was asymptomatic at the diagnosis, but the patient had worsening hypercalcemia and osteoporosis, and developed acute renal colic. He then underwent parathyroidectomy with resection of a single adenoma and normalization of calcium and parathyroid hormone levels. Clinical and therapeutic implications of this rare association are discussed. LEARNING POINTS: The coexistence of KS and PHPT is very uncommon.Patients with mild PHPT often have nonspecific symptoms that may be confused and superimposed with those of hypogonadism.KS patients, especially when young and already osteoporotic at diagnosis, should be screened for other causes of secondary osteoporosis, in particular PHPT.

11.
Br J Radiol ; 85(1018): e814-25, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22514101

RESUMEN

OBJECTIVE: Perfusion CT may have the potential to quantify the degree of angiogenesis of solid tumours in vivo. This study aims to identify the practical and technical challenges inherent to the technique, and evaluate its feasibility in colorectal tumours. METHODS: 51 patients from 2 institutions prospectively underwent a single perfusion CT on 2 different multidetector scanners. The patients were advised to breath-hold as long as possible, followed by shallow breathing, and were given intravenous buscopan to reduce movement. Numerous steps were explored to identify the challenges. RESULTS: 43 patients successfully completed the perfusion CT as per protocol. Inability to detect the tumour (n=3), misplacement of dynamic sequence co-ordinates (n=2), failure of contrast injection (n=2) and displacement of tumour (n=1) were the reasons for failure. In 14 cases excessive respiratory motion displaced the tumour out of the scanning field along the temporal sequence, leading to erroneous data capture. In nine patients, minor displacements of the tumour were corrected by repositioning the region of interest (ROI) to its original position after reviewing each dynamic sequence slice. In 20 patients the tumour was stable, and data captured from the ROI were representative, and could have been analysed by commercially available Body Tumor Perfusion 3.0® software (GE Healthcare, Waukesha, WI). Hence all data were manually analysed by MATLAB® processing software (MathWorks, Cambridge, UK). CONCLUSION: Perfusion CT in tumours susceptible to motion during acquisition makes accurate data capture challenging and requires meticulous attention to detail. Motion correction software is essential if perfusion CT is to be used routinely in colorectal cancer.


Asunto(s)
Neoplasias del Colon/irrigación sanguínea , Neovascularización Patológica/diagnóstico por imagen , Imagen de Perfusión/métodos , Neoplasias del Colon/diagnóstico por imagen , Medios de Contraste , Estudios de Factibilidad , Humanos , Arteria Ilíaca/diagnóstico por imagen , Yohexol , Movimiento , Estudios Prospectivos , Programas Informáticos , Tomografía Computarizada por Rayos X/métodos
12.
J Phys Chem A ; 116(3): 1110-8, 2012 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-22242788

RESUMEN

The (Z)-4,4,4-trifluoro-3-(2-hydroxyethylamino)-1-(2-hydroxyphenyl)-2-buten-1-one (C(12)H(12)F(3)NO(3)) compound was thoroughly studied by IR, Raman, UV-visible, and (13)C and (19)F NMR spectroscopies. The solid-state molecular structure was determined by X-ray diffraction methods. It crystallizes in the P2(1)/c space group with a = 12.1420(4) Å, b = 7.8210(3) Å, c = 13.8970(5) Å, ß = 116.162(2)°, and Z = 4 molecules per unit cell. The molecule shows a nearly planar molecular skeleton, favored by intramolecular OH···O and NH···O bonds, which are arranged in the lattice as an OH···O bonded polymer coiled around crystallographic 2-fold screw-axes. The three postulated tautomers were evaluated using quantum chemical calculations. The lowest energy tautomer (I) calculated with density functional theory methods agrees with the observed crystal structure. The structural and conformational properties are discussed considering the effect of the intra- and intermolecular hydrogen bond interactions.


Asunto(s)
Aminas/química , Butanonas/química , Etilaminas/química , Butanonas/síntesis química , Cristalografía por Rayos X , Etilaminas/síntesis química , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Estructura Molecular , Teoría Cuántica , Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Espectrometría Raman , Estereoisomerismo
13.
Can Respir J ; 17(6): e106-8, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-21165354

RESUMEN

A 21-year-old man presented to hospital with a two-month history of productive cough with no other symptoms. Radiology revealed a cavitating lesion in the left upper lobe for which a variety of diagnoses were considered. A biopsy revealed primary pulmonary Hodgkin's lymphoma. Primary pulmonary Hodgkin's lymphoma is an uncommon initial presentation; lung lesions usually occur later in the course of the disease. Following diagnosis, the patient began chemotherapy and full remission was achieved.


Asunto(s)
Enfermedad de Hodgkin/diagnóstico , Neoplasias Pulmonares/diagnóstico , Pulmón/diagnóstico por imagen , Diagnóstico Diferencial , Enfermedad de Hodgkin/tratamiento farmacológico , Humanos , Pulmón/patología , Neoplasias Pulmonares/tratamiento farmacológico , Masculino , Radiografía , Adulto Joven
14.
Dalton Trans ; 39(16): 3931-43, 2010 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-20372718

RESUMEN

The free H(2)xspa ligands [xspa = pspa, Clpspa, tspa or fspa where p = 3-(phenyl), Clp = 3-(2-chlorophenyl), t = 3-(2-thienyl), f = 3-(2-furyl) and spa = 2-sulfanylpropenoato], their Zn(II) complexes of formula [HQ](2)[Zn(xspa)(2)] (HQ = diisopropylammonium) and the Cd(II) equivalents were prepared and characterized by elemental analysis and by IR, Raman and NMR ((1)H, (13)C) spectroscopy. X-Ray studies of the crystal structures of [HQ](2)[Zn(pspa)(2)], [HQ](2)[Zn(Clpspa)(2)], [HQ](2)[Zn(tspa)(2)] and [HQ](2)[Zn(fspa)(2)] show that the zinc atom is coordinated to two O atoms and two S atoms of the ligands in a distorted tetrahedral ZnO(2)S(2) environment. In the structures of [HQ](2)[Cd(pspa)(2)] and [HQ](2)[Cd(Clpspa)(2)] the cadmium atom is coordinated to three S atoms and two carboxylato O atoms of the ligands in a distorted trigonal bipyramidal environment. The interchange of ligands between Zn(II) and Cd(II) was studied by (113)Cd NMR spectroscopy. The in vitro protective effect of H(2)xspa and their Zn(II) complexes against Cd toxicity was investigated using the human hepatocarcinoma HepG2 cell line and the pig renal proximal tubule LLC-PK1 cell line. The incorporation of Zn(II) was found to be relevant in the case of H(2)pspa, with an increase observed in the cell viability of the LCC-PK1 cells with respect to the value for the free ligand.


Asunto(s)
Acrilatos/química , Cadmio/toxicidad , Complejos de Coordinación/química , Sustancias Protectoras/química , Zinc/química , Animales , Línea Celular , Complejos de Coordinación/síntesis química , Cristalografía por Rayos X , Células Hep G2 , Humanos , Espectroscopía de Resonancia Magnética , Conformación Molecular , Sustancias Protectoras/síntesis química , Porcinos
15.
Anal Chim Acta ; 594(2): 219-25, 2007 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-17586118

RESUMEN

A Flow Injection Analysis (FIA) spectrofluorimetric method for calcium determination in ice cores was optimised in order to achieve better analytical performances which would make it suitable for reliable calcium measurements at ppt level. The method here optimised is based on the formation of a fluorescent compound between Ca and Quin-2 in buffered environment. A careful evaluation of operative parameters (reagent concentration, buffer composition and concentration, pH), influence of interfering species possibly present in real samples and potential favourable effect of surfactant addition was carried out. The obtained detection limit is around 15 ppt, which is one order of magnitude lower than the most sensitive Flow Analysis method for Ca determination currently available in literature and reproducibility is better than 4% for Ca concentrations of 0.2 ppb. The method was validated through measurements performed in parallel with Ion Chromatography on 200 samples from an alpine ice core (Lys Glacier) revealing an excellent fit between the two chemical series. Calcium stratigraphy in Lys ice core was discussed in terms of seasonal pattern and occurrence of Saharan dust events.

16.
Oncogene ; 26(6): 917-33, 2007 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-16909116

RESUMEN

We characterized differential gene expression profiles of fibroblast cell lines harboring single or double-homozygous null mutations in H-ras and N-ras. Whereas the expression level of the individual H-, N- and K-ras genes appeared unaffected by the presence or absence of the other ras loci, significant differences were observed between the expression profiles of cells missing N-ras and/or H-ras. Absence of N-ras produced much stronger effects than absence of H-ras over the profile of the cellular transcriptome. N-ras(-/-) and H-ras(-/-) fibroblasts displayed rather antagonistic expression profiles and the transcriptome of H-ras(-/-) cells was significantly closer to that of wild-type fibroblasts than to that of N-ras(-/-) cells. Classifying all differentially expressed genes into functional categories suggested specific roles for H-Ras and N-Ras. It was particularly striking in N-ras(-/-) cells the upregulation of a remarkable number of immunity-related genes, as well as of several loci involved in apoptosis. Reverse-phase protein array assays demonstrated in the same N-ras(-/-) cells the overexpression and nuclear migration of tyrosine phosphorylated signal transducer and activator of transcription 1 (Stat1) which was concomitant with transcriptional activation mediated by interferon-stimulated response elements. Significantly enhanced numbers of apoptotic cells were also detected in cultures of N-ras(-/-) cells. Our data support the notion that different Ras isoforms play functionally distinct cellular roles and indicate that N-Ras is significantly involved in immune modulation/host defense and apoptotic responses.


Asunto(s)
Redes Reguladoras de Genes , Proteínas ras/deficiencia , Proteínas ras/metabolismo , Animales , Línea Celular , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Ratones , Familia de Multigenes , Análisis de Secuencia por Matrices de Oligonucleótidos , Proteínas ras/clasificación , Proteínas ras/genética
17.
Nature ; 440(7083): 491-6, 2006 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-16554810

RESUMEN

Sea ice and dust flux increased greatly in the Southern Ocean during the last glacial period. Palaeorecords provide contradictory evidence about marine productivity in this region, but beyond one glacial cycle, data were sparse. Here we present continuous chemical proxy data spanning the last eight glacial cycles (740,000 years) from the Dome C Antarctic ice core. These data constrain winter sea-ice extent in the Indian Ocean, Southern Ocean biogenic productivity and Patagonian climatic conditions. We found that maximum sea-ice extent is closely tied to Antarctic temperature on multi-millennial timescales, but less so on shorter timescales. Biological dimethylsulphide emissions south of the polar front seem to have changed little with climate, suggesting that sulphur compounds were not active in climate regulation. We observe large glacial-interglacial contrasts in iron deposition, which we infer reflects strongly changing Patagonian conditions. During glacial terminations, changes in Patagonia apparently preceded sea-ice reduction, indicating that multiple mechanisms may be responsible for different phases of CO2 increase during glacial terminations. We observe no changes in internal climatic feedbacks that could have caused the change in amplitude of Antarctic temperature variations observed 440,000 years ago.


Asunto(s)
Ambiente , Hielo , Hierro , Calcio/análisis , Clima , Hierro/análisis , Biología Marina , Mesilatos/análisis , Océanos y Mares , Periodicidad , Sodio/análisis , América del Sur
18.
Med. mil ; 61(4): 338-344, oct.-dic. 2005. ilus, tab
Artículo en Es | IBECS | ID: ibc-056888

RESUMEN

Objetivos: Evidenciar las posibles contaminaciones locales de algunos elementos traza y metales pesado en la Antártida. Lugar de realización: Muestras procedentes de la Isla Livingston, Base Juan Carlos I y la Isla Decepción, base Gabriel de Castilla (Shetland del Sur). Determinaciones analíticas en el Servicio de Toxicología del Instituto de Medicina Preventiva de la Defensa. Diseño: Colaboración de la Unidad Funcional de Medicina Antártica del Hospital General Básico de la Defensa de Cartagena y el Instituto de Medicin aPreventiva de la Defensa. Material y métodos: Equipo de acoplamiento inductivo de plasma con un espectómetro de masas como detector (ICP-MS) y cámara de reacción dinámica (DRC). Resultados: Se determina la concentración de Mn, Cu, Mo, Ag, U, Cr, Ni, Cd, Sb, Ba, TI, Pb, Th, Al, Zn y HG en muestras de agua de mar y hielo flotante en zonas de tránsito alejadas aproximadamente 300 metros del mismo. Las concentraciones encontradas en la muestra de hielo flotante en zona de tránsito y alejadas aproximadamente 300 metros del mismo. Las concentraciones encontradas en la muestra de hielo flotante en zona de tránsito son superiores para todos los elementos excepto el mercurio. Conclusiones: Existe una contaminación local en las zonas de tránsito para la mayoría de los elementos de estudio. Los valores encontrados son comparables a los reflejados en la bibliografía aunque algo más elevados en el caso del cadmio, el manganeso y el antimonio y claramente superiores en el caso del cobre, zinc y el cromo. Los datos parecen corroborar la existencia de una mayor concentración de cadmio en la zona de la Antártida


No disponible


Asunto(s)
Oligoelementos/aislamiento & purificación , Metales Pesados/aislamiento & purificación , Contaminación Costera , Contaminación Ambiental/análisis , Contaminantes del Agua/análisis , Contaminantes Ambientales/aislamiento & purificación , Regiones Antárticas , Agua de Mar/análisis , Hielo/análisis , Cadmio/aislamiento & purificación , Espectrometría de Masas
19.
J Environ Monit ; 7(12): 1265-74, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16307082

RESUMEN

During the 2002-2003 austral summer field season, aerosol samples were collected at a coastal (Terra Nova Bay--Northern Victoria Land) and an inland site (Dome C--East Antarctic Plateau). The sampling was carried out by stacked filter units made up of two filters at different porosity (5.0 and 0.4 microm at Terra Nova Bay and 3.0 and 0.4 microm at Dome C), able to roughly separate a coarse from a fine fraction. At Dome C, a further investigation on aerosol size distribution was performed by an inertial impactor able to collect aerosol particles on 8 size classes (from 10 to 0.4 microm). Atomic Force Microscopy was applied to the filter collecting the finer fraction in both sites in order to assess the real cut-off value of the filter sandwich apparatus and to reconstruct the volume size distribution. At the employed flow conditions, the real cut-off value was revealed to be about one third with respect to the filter nominal porosity in both stations. The size distribution plots showed a bimodal distribution with a mode centered around 0.22 microm in both the sites and a second broader mode which is centered between 0.3 microm and 1.2 microm diameter at Terra Nova Bay and shifted toward higher values (centred around 1.0 microm diameter) at Dome C. Each filter was analysed for the main and trace ionic components allowing evaluation of the contributions of primary and secondary aerosol sources at the two sites as a function of the particle size class. The coastal site is mainly affected by primary and secondary marine inputs: the sea spray contribution (Na+, Mg2+, Cl- and ssSO4(2-)) is dominant (77% w/w) in the coarse fraction whereas the biogenic source (methanesulfonate and nssSO4(2-)) prevails (67.5% w/w) in the fine fraction. In this fraction a significant contribution (15.5% w/w) is provided by ammonium likely to be related to surrounding penguin colonies. Dome C atmosphere is characterised by fine particles arising from secondary sources and long-range transport processes. The main component in the fine and coarse fractions at Dome C is sulfate whose nssSO4(2-) represents the 99.5% and the 92.3%(w/w) in fine and coarse fraction, respectively. The observed agreement between nssSO4(2-) and methanesulfonate temporal profiles in the fine fraction demonstrates that biogenic emissions dominate the inland background aerosol. Results from the sampling by the 8-stage impactor at Dome C are presented here: chloride and nitrate are mainly deposited on the 10-2.1 microm stages while the highest sulfate concentration was found in the submicrometric fraction which turned out to be the most acidic. Such a distribution is able to prevent nitrate and chloride re-emission as gaseous HCl and HNO3 in the 10-2.1 microm stages, arising from the exchange reaction between chloride and nitrate salts and sulfuric acid. Moreover, the concentration peak observed for nitrate in coarser fractions is probably related also to the formation of hygroscopic NH4NO3 particles and nitrate adsorption on sea salt particles.


Asunto(s)
Aerosoles/análisis , Regiones Antárticas , Cloruros/análisis , Monitoreo del Ambiente , Magnesio/análisis , Microscopía de Fuerza Atómica , Tamaño de la Partícula , Estaciones del Año , Agua de Mar , Sulfatos/análisis
20.
Bol. méd. postgrado ; 20(2): 81-86, abr.-jun. 2004. tab, graf
Artículo en Español | LILACS | ID: lil-503828

RESUMEN

La Enfermedad de Chagas constituye un problema de salud pública en Venezuela, cuyas alteraciones están representadas fundamentalmente por el desarrollo de miocardiopatías incapacitantes. En la actualidad, las causas de las miocardiopatías no son realmente conocidasy tampoco existe tratamiento; sin embargo, dentro de la teoria neurogénica se ha postulado que el Sistema Colinérgico est  involúcrado en su desarrollo. Con el fin de dilucidar el estado de Receptor Colinérgico Muscarínico (RCM) en ésta enfermedad, se establecieron dos grupos de animales: Control (ratas sanas) y Experimental (ratas con Enfermedad de Chagas en etapa crónica), posteriormente las ratas fueron sacrificadas, disecando en corazón Ventrículo Izquierdo (VI), Ventrículo Derecho (VD), Tabique Interventricular (TIV), Aurícula (Au) y en el encéfalo Tronco Encefálico (TE). Se determinó la cantidad de proteínas mediante el método de Lowry, la densidad de RCM y los efectos de agonistas (Carbacol) y antagonistas selectivos (Pirenzepina, Metoctramina, 4-DAMP y Tropicamida) por medio de ensayos de radioligandos usando [³H]-QNB como marcador radioactivo. Los resultados mostraron en TE una disminución significativa de la cantidad de proteínas en ratas con Enfermedad de Chagas; en VD se encontró una supersensibilidad significativa del RCM en ratas Chagásicas, mientras que en TIV, VI y Au no se observaron diferencias significativas entre ambos grupos. En las curvas de desplazamiento de [³H]-QNB por agonistas y antagonistas selectivos, no se encontraron diferencias significativas en el perfil de desplazamiento y en los valores de CI50, al comparar los dos grupos. En conclusión la expresión de proteínas y del RCM se encuentran alteradas en TE y VD, respectivamente.


Asunto(s)
Animales , Ratas , Cardiomiopatías , Enfermedad de Chagas , Ratas Sprague-Dawley , Salud Pública , Venezuela
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