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Biomedical subjects

L Gutiérrez

Publications and source records attributed to L Gutiérrez.

At least 19 recordsLinked to original sources
PubMed2006

Wannier-stark ladders in one-dimensional elastic systems.

The optical analogues of Bloch oscillations and their associated Wannier-Stark ladders have been recently analyzed. In this Letter we propose an elastic realization of these ladders, employing for this purpose the torsional vibrations of specially designed one-dimensional elastic systems. We have measured, for the first time, the ladder wave amplitudes, which are not directly accessible either in the quantum-mechanical or optical cases. The wave amplitudes are spatially localized and coincide rather well with theoretically predicted amplitudes. The rods we analyze can be used to localize different frequencies in different parts of the elastic systems and vice versa.

Journal Article↗
PubMed2006

Magnetic and structural study of the state of iron in the oral haematinic ferrimannitol ovoalbumin.

From magnetic and structural analyses performed on ferrimannitol ovalbumin, iron in this drug is observed to be present as two-line ferrihydrite nanoparticles, of around 4 nm in diameter, which are superparamagnetic above approximately 20 K. Among other parameters, the temperature dependence of the magnetic out-of-phase susceptibility of this compound has been fully characterised and yields results clearly different from that of ferritin. This characterisation, performed for the first time for an oral haematinic, is of interest in the context of future pharmacological studies of this compound.

Ferric Compounds↗
PubMed2005

Locally periodic Timoshenko rod: experiment and theory.

The flexural vibrations of a locally periodic rod, which consists of N unit cells, are discussed both from the experimental and theoretical points of view. Timoshenko's beam theory and the transfer matrix method are used to calculate the normal-mode frequencies and amplitudes. The theoretical values are then compared with the experimental ones, which are obtained using an electromagnetic acoustic transducer (EMAT). Good agreement between the numerical results and the experimental measurements is obtained. It is shown that as N grows, a band spectrum emerges.

Acoustics↗
PubMed2004

Magnetic characterisation of rat muscle tissues after subcutaneous iron dextran injection.

Ex vivo freeze-dried rat muscle tissues, collected at different times t after a single dose of subcutaneously injected iron dextran, have been magnetically characterised. The AC susceptibility of the tissues shows an overall superparamagnetic behaviour and the dependence on t of, especially, the out-of-phase component is remarkably systematic despite the fact that each tissue originates in a different rat individual. The experiments show that the akaganéite (beta-FeOOH) nanoparticles contained in the injected drug are progressively degraded in the living tissue and, at times of the order of 1 month and for all the analysed rat individuals, converge to a magnetically well-defined species with much narrower magnetic activation energy distribution than iron dextran. Thorough transmission electron microscopy experiments of the same tissues indicate the presence of oxyhydroxide particles, whose size decreases for increasing t in agreement with the interpretation of the magnetic susceptibility. The conclusions drawn from the magnetic study do well correspond to the properties of the whole tissue since no biochemical extraction work has been done. The AC susceptibility appears to be a valuable and complementary tool in pharmacological studies of iron-containing drugs.

Animals↗
PubMed2003

[Neuropsychological and behavioural impairments resulting from bilateral thalamic infarct].

The neuropsychological characteristics of a patient with a bilateral thalamic infarct in the posterior communicating artery territory due to basilar artery thrombosis are described. MRI examination showed bilateral thalamic acute ischemic lesions in the zone anterior to the tuberothalamic branches. In the cognitive exploration, the patient showed verbal and visual memory disorders, impairment of the executive functions including inability to generate and make decisions and behavioural disorders including lack of inhibition, euphoria, and occasional aggressiveness. Two months later the patient had improved in the neuropsychological test scores but still suffered from severe recent memory loss, and certain behavioural disorders including lack of inhibition and euphoria. Other cases on thalamic infarcts with cognitive and behavioural impairments due to disconnection of the front subcortical pathways have been described in the literature.

Adult↗
PubMed2002

[Spirometry: quality in the respiratory medicine clinics of a public health care area].

BACKGROUND: Spirometry can be considered a routine way to evaluate patients with respiratory complaints, both inside and outside the hospital setting. OBJECTIVE: To assess the quality of spirometry in a public health care area with respect to two factors: the technicians' performance and the calibration of spirometers. MATERIAL AND METHOD: Four health care clinics were studied. Four technicians participated and the four spirometers were tested at different volumes (calibration syringes 1L and 3L) and different flows (explosive decompression). Eight patients with COPD participated in the study of inter-technician variability. RESULTS: Agreement among the technicians was very high: 0.98-0.99 for FEV1 and 0.91-0.98 for FVC. The mean results obtained by the technicians were: FEV1 = 2.15 0.03, range 2.20-2.14; FVC = 3.25 0.05, range 3.30-3.21 (ns). Volumetric readings from the spirometers were correct for the 1I calibration syringe, but 2 out of 4 spirometers lost linearity with the 3I calibration syringe. One spirometer gave readings out of range for all flow levels, and 2 out of 4 spirometers were out of range at low flows. CONCLUSIONS: 1. Results obtained by different technicians were not significantly different and there was high agreement among them, confirming that performance of spirometry was good. 2. The spirometers showed poor linearity at low flows.

Aged↗
PubMed2002

Compressional and torsional wave amplitudes in rods with periodic structures.

To measure and detect elastic waves in metallic rods a low-frequency electromagnetic-acoustic transducer has been developed. Frequencies range from a few hertz up to hundreds of kilohertz. With appropriate configuration of the transducer, compressional or torsional waves can be selectively excited or detected. Although the transducer can be used in many different situations, it has been tested and applied to a locally periodic rod, which consists of a finite number of unit cells. The measured wave amplitudes are compared with theoretical ones, obtained with the one-dimensional transfer matrix method, and excellent agreement is obtained.

Journal Article↗
PubMed2001

Copper(II) complexes with 4-amino-N-[4,6-dimethyl-2-pyrimidinyl]benzenesulfonamide. Synthesis, crystal structure, magnetic properties, EPR, and theoretical studies of a novel mixed mu-carboxylato, NCN-bridged dinuclear copper compound.

New Cu(II) complexes of sulfamethazine (4-amino-N-[4,6-dimethyl-2-pyrimidinyl]benzenesulfonamide, HL) [Cu(2)(CH(3)COO)(2)(L)(2)].2dmf (1) and ([Cu(L)(2)].2H(2)O)(infinity) (2) were prepared and structurally characterized. Compound 1 crystallizes in the monoclinic system, space group P2(1)/n, with a = 8.9486(9) A, b = 15.0956(12) A, c = 16.542(3) A, beta = 105.584(15) degrees, and Z = 2. Compound 2 crystallizes in the monoclinic system, space group P2(1)/c, with a = 13.8097(8) A, b = 14.5765(4) A, c = 13.7853(15) A, beta = 96.033(9) degrees, and Z = 1. In compound 1 two copper ions are linked by two syn-syn acetates and two nonlinear NCN bridging groups pertaining to the deprotonated sulfamethazine ligands. Each copper center presents a nearly square planar geometry. Magnetic susceptibility data for 1 show a strong antiferromagnetic coupling with 2J = -216.7 cm(-)(1). The EPR spectra at the X- and Q-band frequencies present the signals corresponding to the dinuclear entity, being the zero-field splitting parameter, D = 0.265 cm(-)(1). The antiferromagnetic exchange coupling is discussed using DFT calculations on some model compounds with NCN bridging ligands and also on model structures with mixed mu-acetato and NCN bridges. The copper in the polymeric compound 2 is five coordinate. The CuN(5) chromophore has a highly distorted square pyramidal geometry with small axial N-Cu-N angles of 65.53(14) and 59.90(13) degrees. In the structure a sulfamethazinate anion binds to one copper through the sulfonamido and pyrimidine N atoms and to an adjacent copper via the amino N atom.

Journal Article↗
PubMed2001

[Gastrointestinal signs and symptoms during pregnancy and postpartum in a sample of Spanish women].

OBJECTIVE: To describe the evolution of the signs and more frequent gastrointestinal symptoms during the pregnancy and in the two weeks later the birth. METHODS SUBJECTS: 583 pregnant women, elects in an accidental way, interviewees between the 8 and 12 weeks of gestation (n = 133), among 18 and 22 (n = 155), among 37 and 42 (n = 203) and two weeks after the childbirth (n = 92) and coming from centers of health and hospitals of the Comunidad Valenciana and Murcia. The questionnaire, answered in a voluntary way by interview, it contained a listing on the signs and more frequent gastrointestinal symptoms during the pregnancy, and she answered on the presence or not of the same ones in the two weeks previous to the moment of the interview. RESULTS: The percentage of nauseas and vomits, although higher in the first trimester, stays around the 25-30% in the third gestation trimester. The heartburn is presented in 58.6% of the pregnant women in the third trimester. The sialorrea is presented in 7.7% of all the pregnant women and she stays during the whole gestation. The constipation stays constant during the gestation above at the 25-30%. The prevalence of haemorrhoids to the beginning of the gestation is over to 8% to be located in the postpartum in 53.3%. CONCLUSIONS: The description of the evolution of the signs and symptoms of the pregnancy described in the obstetrics manuals don't come up with our data.

Adolescent↗
PubMed2001

An integrated physical map of 8q22-q24: use in positional cloning and deletion analysis of Langer-Giedion syndrome.

We have developed an integrated map for a 35-cM area of human chromosome 8 surrounding the Langer-Giedion syndrome deletion region. This map spans from approximately 8q22 to 8q24 and includes 10 hybrid cell intervals, 89 polymorphic STSs, 118 ESTs, and 37 known genes or inferred gene homologies. The map locations of 25 genes including osteoprotegerin, syndecan-2, and autotaxin have been refined from the general locations previously reported. In addition, the map has been used to indicate the location of nine deletions in patients with Langer-Giedion syndrome and trichorhinophalangeal syndrome type I to demonstrate the potential usefulness of the map in the analysis of these complex syndromes. The map will also be of interest to anyone trying to clone positionally disease genes in this region, such as Cohen syndrome (8q22-q23), Klip-Feil syndrome (8q22.2), hereditary spastic paraplegia (8q24), and benign adult familial myoclonic epilepsy (8q23.3-q24.1).

Child↗
PubMed2000

High prevalence of serum antibodies to Ras and type 16 E4 proteins of human papillomavirus in patients with precancerous lesions of the uterine cervix.

Serum samples from 38 healthy women and 55 women with different types of cervical lesions were investigated for the presence of antibodies to Ras and against E4 and E7 proteins of human papillomavirus type 16 (HPV-16). Our results showed that anti-E7 antibodies were closely associated with cervical cancer (75%), as previously reported. Interestingly, E4 antibodies showed higher prevalence in condyloma lesions (79%; 11/14) than in cervical cancer (60%; 12/20). We also identified 11% (4/38) of healthy individuals as positive for E4 antibodies, which suggests an early immune recognition of this protein. Patients with condyloma and cervical intraepithelial neoplasia (CIN) also showed higher prevalences of Ras antibodies (approximately 40%) than cervical cancer patients (10%; 2/20). By sequencing part of the ras genes and using different Ras antigens, we showed that serum antibodies from patients were not directed to a Ras mutation, since wild-type cHa-Ras protein was recognized by these antibodies. In addition, patients positive for Ras antibodies (94%) were also positive for E4 antibodies, suggesting an association between these. The high prevalence of antibodies against Ras and E4 proteins in pre-malignant lesions opens the possibility of using both antibodies as early markers for potential cervical cancer patients.

Adult↗
PubMed1998

Functional analysis of HIV-1 reverse transcriptase motif C: site-directed mutagenesis and metal cation interaction.

Motif C, present in all polymerases, has been proposed to be part of the catalytic and metal binding site of the enzyme, suggesting that polymerases have a common origin. Previously, we have shown that the metal ion manganese induces alterations in nucleotide substrate specificity in some polymerases. However, it is not known if the active site responsible for incorporation of nonspecific substrates is the same as that which incorporates specific ones. Here we show that manganese enables HIV-1 reverse transcriptase (RT) to incorporate rNTP's using RNA as a template, thus behaving as an RNA replicase. Also, we show that the mutation D186H in motif C strongly affects the natural DNA polymerase activity and that the RNA replicase activity becomes undetectable, suggesting that both activities depend on the same active site. This mutation changes the metal ion preference, with mutant RT presenting only 0.5% of the wild-type DNA polymerase activity in the presence of magnesium but 1.6% of the same activity in the presence of manganese. This variation in cation preference suggests that residue D186 is part of the metal binding site. Since residue D186 of motif C is essential for both activities and appears to be involved in the binding of an important cation needed for the specific activity, our results support the idea of a common origin for all polymerases, from an ancestral unspecified polymerase containing at least motif C.

Binding Sites↗
PubMed1997

Rhabdomyolysis in patients with acute lymphoblastic leukemia.

The objective of this paper is to report 5 cases of rhabdomyolysis (RML) in patients with acute leukemia (AL). This occurred consecutively after the administration of chemotherapy, during the ensuing period of myelosuppression. Thirty-six patients with AL received, in a three-month period, 51 cycles of combined chemotherapy which included, in all of them, cytosine arabinoside (ARA-C); among them, along with myelosuppression, five experienced fever, infectious complications, gastrointestinal tract symptoms and severe myalgias. Serum creatine kinase (CK), liver function tests and a light microscopy muscle biopsy were performed on all of them. Ten-17 days after receiving chemotherapy, five patients (4 males and 1 female) with acute lymphoblastic leukemia developed incapacitating myalgias in neck, thighs and arms. CK and/or alanine aminotransferase and aspartate aminotransferase were increased 5-24 times above the normal range in four of these patients, and the muscle biopsy showed focal RML in all five. Myalgias were self-limited and lasted 4-10 days. In addition to the chemotherapy, other factors known to be capable of producing RML, such as sepsis, other medications, and dehydration were found. In conclusion, myalgias were due to focal RML produced probably by a combination of factors, particularly the chemotherapy along with dehydration due to gastrointestinal complications, infection, and the use of diverse antibiotics. The endemic nature of the finding in such a short period of time is outstanding.

Adolescent↗
PubMed1997

[Cardiac tamponade as a clinical symptom of systemic lupus erythematosus].

Pericarditis is the most frequent cardiac manifestation of systemic lupus erythematosus (SLE), but pericardial effusion causing tamponade rarely occurs, and it is even less frequent for the pericardial tamponade to be the presenting feature of SLE. We report a case of pericardial tamponade due to SLE with severe hemodynamic involvement as the clinical presentation of the disease. We comment on its clinical course and its rarity in the medical literature.

Adult↗
PubMed1997

[Radiosurgical labeling of non-palpable mammary lesions].

BACKGROUND: The frequency of breast cancer is increasing worldwide and mammography allows the diagnosis of concealed lesions. AIM: To assess the diagnostic yield for carcinoma of non palpable lesions detected by mammography. PATIENTS AND METHODS: We studied 46 patients, aged 24 to 67 years old, in whom a radiosurgical labeling of non palpable mammary lesions was performed. In all patients, a surgical biopsy was obtained, but the pathological study was available in only 40 patients. RESULTS: The mammographic appearance of lesions were microcalcifications in 40% of women, stellate images in 27.5%, asymmetry in density in 5% and the association of microcalcifications and other signs in 20%. Seventy seven percent of lesions were benign. Four patients had an in situ ductal carcinoma, two had a predominantly in situ carcinoma and 4 had an invasive ductal carcinoma. CONCLUSIONS: Our results are similar to those reported abroad. The finding of 5 minimal carcinomas underscores the effectiveness of mammography as a screening method for breast cancer.

Adult↗
PubMed1995

[Size and echogenicity of the pancreas in Chilean adults: echotomography study in 261 patients].

The aim of this work was to perform ultrasonographic measurements of normal pancreas in the Chilean population. Among 5000 subjects referred for an ultrasound abdominal examination, those without history of alcoholism, pancreatitis or liver disease were selected for the study. 261 individuals (157 female) aged 20 to 79 years were studied. The size of the head of the pancreas ranged from 6 to 28 mm (17.7 +/- 4.2 mm), the body size ranged from 4 to 23 mm (10.1 +/- 3.8 mm) and the tail size from 5 to 28 mm (16.4 +/- 4.2 mm). These figures are lower than those reported in Europe and North America. No size differences were observed according to sex or body frame. Progressive declines in size with age, were observed in all pancreatic segments. No hypoecogenic pancreas were observed. A new technique to improve pancreatic ultrasonographic vision is proposed.

Adult↗
PubMed1995

[Osteopoikilosis. A clinical case].

We report a 35 years old female presenting with a right wrist pain. Physical examination was normal but, on a hand X ray examination, multiple dense para-articular bone foci were observed. Studying the rest of the skeleton, similar alterations were found in pelvis, knees, ankles, feet, shoulders and elbows. Osteopoikilosis is an infrequent sclerotic bone dysplasia. Its diagnosis is made by the observation of multiple dense, nodular and symmetrical images of para-articular location on bone X ray examinations. It has no clinical or pathological importance. Thus, it must be distinguished from osteoblastic bone metastases.

Adult↗