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Biomedical subjects

A Márquez

Publications and source records attributed to A Márquez.

At least 19 recordsLinked to original sources
PubMed2006

Achromatic diffractive lens written onto a liquid crystal display.

We propose a programmable diffractive lens written onto a liquid crystal display (LCD) that is able to provide equal focal lengths for several wavelengths simultaneously. To achieve this goal it is necessary that the LCD operate in the phase-only regime simultaneously for the different wavelengths. We design the appropriate lens for each wavelength, and then the lenses are spatially multiplexed onto the LCD. Various multiplexing schemes have been analyzed, and the random scheme shows the best performance. We further show the possibility of finely tuning the chromaticity of the focal spot by changing the relative weights of the multiplexing among the various wavelengths.

Journal Article↗
PubMed2006

No evidence of association of the MYO9B polymorphisms with celiac disease in the Spanish population.

Inconsistent results concerning the association of polymorphisms in the MYO9B gene with celiac disease (CD) have been recently published. This gene encodes a myosin with a guanosine-triphosphatase (GTPase)-activating protein domain for the Rho-family of small G proteins, which are involved in cytoskeleton remodeling and therefore potentially involved in intestinal permeability. Functional and positional reasons led us to investigate the role of MYO9B polymorphisms in the Spanish CD population. A case-control study, including 415 CD patients and 433 ethnically matched healthy controls, and a familial study, including parents of 145 of those CD patients, was performed. Six MYO9B variants previously associated with CD were analyzed: rs2305767, rs2279003, rs962917, rs1457092, rs2305765 and rs2305764. No MYO9B variants or MYO9B haplotypes were found associated with CD, either before or after stratification of the patients for the human leucocyte antigen (HLA)-DQ2-positive risk factor. The family study revealed no distorted transmission of the aforementioned MYO9B polymorphisms or haplotypes. Our results support a negligible influence of this gene on CD predisposition.

Case-Control Studies↗
PubMed2004

Treatment of stage I and II Hodgkin's lymphoma with ABVD chemotherapy: results after 7 years of a prospective study.

BACKGROUND: Chemotherapy with ABVD (doxorubicin, bleomycin, vinblastine and darcarbacine) schedule is the standard treatment for advanced Hodgkin's lymphoma. Certain facts, including a low toxicity compared with MOPP/ABV (mechlorethamine, vincristine, procarbazine, prednisone, doxorubicin, bleomycin and vinblastine) and minimal potential for inducing second neoplasias or patient sterility, support the use of ABVD to treat early disease stages. In the present study, we prospectively evaluated the long-term efficacy and toxicity of six cycles of ABVD as treatment for early-stage Hodgkin's lymphoma. PATIENTS AND METHODS: From January 1990 to June 2002, 95 patients with stage I and II Hodgkin's lymphoma were treated with six ABVD cycles. Fifteen patients who met the criteria for mediastinal bulky disease also received further radiotherapy on the mediastinum. RESULTS: After six cycles, 89 patients (94%) showed a complete response (CR) and six patients (6%) showed a partial response (PR). These PRs became CRs after radiotherapy. After a median follow-up of 78 months, 14 patients had relapsed and three had died. Overall survival and progression-free survival rates at 7 years were 96% and 84%, respectively. For patients with stage IA and IIA without mediastinal bulky disease, the survival rates were 97% and 88%, respectively. CONCLUSIONS: The administration of six ABVD cycles is an effective and safe treatment in patients with stage I and II Hodgkin's lymphoma.

Adolescent↗
PubMed2003

[Hepatic amyloidosis as cause of severe intrahepatic cholestasis].

The liver is frequently involved by amyloidosis, but hyperbilirubinemia and liver failure are uncommon features. A mild elevation of the serum alkaline phosphatase value and, less frequently, hepatomegaly are the most common findings. Usually the patients have no symptoms related with the liver involvement; the clinical manifestation and the long term prognosis depends on the renal and cardiac disease. We report an unusual clinical presentation of primary amyloidosis in a previously asymptomatic 65 years old woman who was admitted to the hospital because of ictericia and ascitis mimicking a drug induced acute hepatic failure.

Aged↗
PubMed2001

Bioskin as an affinity matrix for the separation of glycoproteins.

Bioskin is a natural product produced by a mixed culture of Acetobacter xylinum, Saccharomyces cerevisiae and S. pombe cultured on media containing sucrose. It is of fibrillar nature able to retain some proteins, such as cytochrome c, by adsorption, and mainly composed of glucosamine and N-acetyl-D-glucosamine. This makes it possible that, at an adequate pH value, proteins charged as polyanionic molecules, such as catalase, can be retained by ionic adsorption using the positively charged amino groups of the matrix. In addition, bioskin can also be used as an affinity matrix to retain glycoproteins able to perform specific affinity reactions with the amino sugars of the matrix, such as invertase, fetuin or ovalbumin. Its possible use as a chromatographic support is discussed.

Adsorption↗
PubMed2001

Changes in thyroid function in puppies fed a high iodine commercial diet.

Abnormally low(131)I uptakes were noticed in dogs fed with commercial diets at the University Animal Clinic in Buenos Aires, but the total iodine content of eight different commercial diets examined was found to provide an iodine intake above daily requirements. To investigate this anomaly, 18 dogs were distributed into three groups, fed either: (1) a home-prepared diet; (2) a commercial diet; (3) a home-prepared diet supplemented with potassium iodide equivalent to that found in the commercial diet. The(131)I uptake in dogs of groups B and C was significantly decreased, as was basal serum thyroxine (T(4)) and free thyroxine (FT(4)), whereas urinary iodide excretion and serum thyroid stimulating hormone (TSH), were increased. The thyroid releasing hormone (TRH)-TSH test showed an increased response in dogs from group B, while the TRH-T(4)test was inhibited in both groups B and C. The results demonstrate that the excessive amount of iodine present in some commercial diets in Argentina causes a significant impairment of thyroid function and hypothyroidism.

Animals↗
PubMed2001

1,25(OH)2 vitamin D concentration in the plasma of Solanum glaucophyllum intoxicated rabbits.

OBJECTIVE: To test Solanum glaucophyllum calcinotic effects in adult New Zealand White rabbits in relation to cumulative dose and active principle concentration in plasma. DESIGN: An intoxication assay with controls. PROCEDURE: Rabbits were orally dosed with aqueous extracts of dry leaves of S glaucophyllum for 5, 7 or 9 days. During the experiment, body weight, calcaemia and phosphataemia were measured; retinal blood vessel calibre was observed by ophthalmoscopic examination of the ocular fundus. 1,25(OH)2 vitamin D plasma concentration was determined at the end of the experimental periods. Soft tissue calcium concentration and the presence of calcinotic lesions were studied after euthanasia. RESULTS: Toxic effects were evident in S glaucophyllum treated groups (loss of body weight, elevation of soft tissue calcium concentration, and presence of calcinotic lesions). Plasma 1,25(OH)2 vitamin D concentrations were negatively correlated with final body weight (r = -0.97; P < or = 0.001), and positively correlated with renal calcium concentration (r = 0.74; P = 0.02). There was also a significant regression of plasma 1,25 (OH)2 vitamin D concentration on the cumulative dose of S glaucophyllum (R2 = 0.87; P < or = 0.001). CONCLUSIONS: The procedure described here offers a sensitive and practical experimental model for the study of the pathogenesis of enteque seco.

Animals↗
PubMed2001

Secondary prophylactic G-CSF (filgrastim) administration in chemotherapy of stage I and II Hodgkin's lymphoma with ABVD.

UNLABELLED: The purpose of this study was to determine the effect of granulocyte colony-stimulating factor (filgrastim, G-CSF) for maintenance of chemotherapy dose-intensity in patients with stage I or II Hodgkin's lymphoma treated with six cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD). Fifty-six patients with stage I or II Hodgkin's lymphoma treated with ABVD were eligible for secondary prophylactic G-CSF administration because of neutropenia (absolute neutrophil count < 1 x 10(9) /L) causing treatment delay or febrile neutropenia. Patients received 300 microg (total dose) of G-CSF (filgrastim) subcutaneously on days 3 to 7 and 17 to 21 of each cycle in order to prevent dose reduction or delay in subsequent cycles of treatment continuing the G-CSF until completion of chemotherapy. Results showed that 30 (54%) of the patients required the use of G-CSF, 26 (47%) during the first or second cycle. After G-CSF administration delay in chemotherapy did not occur in 25 patients, whereas delays in the fifth or sixth cycle occurred in four patients. Despite treatment with G-CSF, one patient had febrile neutropenia. Dose intensity greater than 90% of that planned was delivered to more the 85% of patients. IN CONCLUSION: Secondary prophylactic G-CSF administration was necessary in more than half of patients with stage I or II Hodgkin's lymphoma during chemotherapy with ABVD. The use of G-CSF allowed maintenance of chemotherapy schedule and dose intensity in the majority of patients.

Adolescent↗
PubMed2001

Extraocular muscle ultrastructural pathology in the paraneoplastic phenomenon associated with retinoblastoma.

Extraocular muscle biopsies were obtained during enucleation because of advanced intraocular retinoblastoma in four patients admitted to the Service of Ophthalmology at the Caracas University Hospital. Slight limitations of ocular movements and strabismus were present in all cases. The electron microscopical analysis showed muscle fibres with slight to severe atrophy exhibiting myopathic structures as nemaline, filamentous and zebra bodies. Fibre necrosis was also observed characterized by sarcomeric hypercontraction, autophagia, sarcolemmal disruption, and mitochondrial swelling. Capillary alterations included endothelial proliferation with intraluminal infoldings and, in some cases, capillary degeneration and necrosis. A mononuclear cell infiltration formed by macrophages and scarce mast cells located next to atrophic fibres and altered capillaries was observed. Additionally, neutrophils were found around capillaries and in their wall. Cancer cells invading muscle tissue were not seen. Two different ethiopathogenic mechanisms for muscle damages seem to be present. Because of the similarity between the microvascular changes we observed and those found in the muscle compromise of several autoimmune diseases, an autoimmune component in the ethiopathogenesis of the observed capillary alterations is proposed. On the other hand, abnormalities observed in muscle fibres are very similar to those in neurogenic atrophy. This study represents the first report on an extraocular muscle paraneoplastic phenomenon associated with orbital tumours.

Child, Preschool↗
PubMed2001

Skeletal muscle microvascular alterations in euthyroid and hypothyroid patients with autoimmune thyroid disease.

An electron microscopic study of skeletal muscle biopsies from euthyroid and hypothyroid patients with autoimmune thyroid disease (ATD) showed the existence of capillary alterations and a mononuclear cell infiltrate. Microvascular abnormalities included thickening and lamination of basement membrane, endothelial proliferation with progressive lumen occlusion, and hypertrophied pericytes. Capillary degeneration was also observed. Macrophages, and scarce lymphocytes and mast cells formed the cell infiltrate. This pathological picture is similar to that found in the muscular compromise of other autoimmune diseases, particularly Graves' hyperthyroidism. This study shows that patients with ATD may have skeletal muscle capillary abnormalities that could probably be related to autoimmunity and are independent of thyroid functional status.

Adult↗
PubMed2000

[Iron and copper in Plagioscion squamosissimus (Piscis: Sciaenidae) from the Orinoco river, Venezuela].

Bauxite explotation of the Orinoco River in recent years is an important source of heavy metals discharge in the ecosystem, changing the natural biochemical flow of these elements and their concentrations in water, sediment and organisms. Iron and copper concentrations were measured in the fish Plagioscion squamosissimus in the Orinoco river, by sampling the fish population for three months (September-November 1998) in the main channel of the middle Orinoco (07 degrees 38' 21.2" N; 66 degrees 19' 10.9" W) and in Castillero lagoon (7 degrees 39' 09" N; 66 degrees 09' 00" W) with 2 and 4 cm mesh sizes. The internal organs of 30 fishes per month and site were stove-dried at 80 degrees C, pulverized and dried in disecator for 30 min to use as indicators with the acid digestion method for predicting the effect of heavy metals. We found relatively high values of iron and copper concentrations in fishes of the lagoon, and high seasonal variations in the iron concentration.

Animals↗
PubMed1998

Liver ultrastructural pathology in mice infected with Plasmodium berghei.

As liver can be an important target organ in malaria, we performed an ultrastructural study of hepatic alterations in the final stage of Plasmodium berghei infection in mice. Significant hepatocyte abnormalities were found. An elevated number of cells showed mitochondria with a high electron-dense matrix and multiple changes in shape and size, alterations in the structure of Golgi complex, swelling and disorganisation of both rough and smooth-surfaced endoplasmic reticulum, differently shaped peroxisome nucleoids, and disappearance of glycogen granules. In other areas the hepatocytes were significantly altered with diminished microvilli and exhibited myelin-like figures, autophagic vacuoles, abundant lipid droplets, and swollen mitochondria in their cytoplasm. Necrotic and atrophied hepatocytes with scarce microvilli in the Disse space and biliary canaliculi could be seen. Parasitised red blood cells and parasite debris were found inside degenerated hepatocytes. Alterations were also noticed in microvasculature, including thickened endothelial cells with swollen mitochondria, lysosomes and autophagic vacuoles in their cytoplasm. Our results demonstrate that hepatocyte damage is an important finding associated with the advanced stages of P. berghei malarial infection, which may lead to liver dysfunction in this disease.

Animals↗