Biomedical subjects

A Ubilla

Publications and source records attributed to A Ubilla.

11 recordsLinked to original sources

PubMed2000

The complex dynamic network of microtubule and microfilament cytasters of the leech zygote.

The organization of the cytoskeleton in the early first interphase zygote and its involvement in organelle redistribution were studied in the glossiphoniid leech Theromyzon trizonare by confocal and electron microscopy, immunofluorescence, and time-lapse video imaging after microinjection of labeled tubulin and/or actin and loading with a mitotracker. The cytoskeleton consists of an inner or endoplasmic and an outer or ectoplasmic domain. The inner domain consists of a monaster whose fibers retract from the zygote periphery by the end of the early first interphase. The outer domain is built upon a network of microtubules and microfilaments cytasters. Short pulses of microinjected labeled actin or tubulin and Taxol treatment demonstrate that cytasters are centers of microtubule and microfilament nucleation. Immunostaining with anti-centrophilin, anti-BX-63, and anti-AH-6 indicates that the network of cytasters includes centrosomal antigens. Cytasters move in an orderly fashion at speeds of 0.5-2 micrometer/min, in an energy-dependent process retarded and finally blocked by the ATP analogue AMP-PNP and high concentrations of Taxol. Colliding cytasters fuse and form larger cytoskeletal nucleation centers. The leech zygote is a highly compartmentalized cell whose cytasters function as articulated components of a very dynamic cytoskeletal system engaged in bulk transportation of organelles during ooplasmic segregation.

Actin Cytoskeleton↗

PubMed2000

Relationship between composition and structure in chitosan-based hybrid films.

Chitosan/poly(aminopropylsiloxane) hybrid films were obtained by blending 3-(aminopropyl)siloxane oligomers (pAPS) with chitosan (CHI). The pAPS oligomers were prepared by the sol-gel method starting from 3-(aminopropyl)triethoxysilane. These hybrids were characterized by chemical, spectroscopic and morphological methods. Scanning electron micrographs of hybrid films of different composition revealed an organized microscopic pattern suggesting the existence of systematic interactions among their components. Comparison of the thermal stabilities and X-ray diffraction patterns as well as FT-IR spectra of the films with those of the pure components revealed that nanocomposites were formed. Similar studies of films including lithium perchlorate, as a third component, showed that addition of certain amount of lithium ions affected the structure of the CHI/pAPS films. When addition of the lithium salt exceeded the homogeneous incorporation limit, a little excess generated anisotropically oriented patterns in the hybrid films.

Chitin↗

PubMed1998

Formation of polar cytoplasmic domains (teloplasms) in the leech egg is a three-step segregation process.

Segregation and proliferation of mitochondria, leading to formation of the teloplasms (pole plasms), were studied in eggs of the leech T. rude by immunocytochemistry, fluorescent time lapse video imaging, confocal and electron microscopy. The translocation of mitochondria was analyzed after loading the egg with either Rhodamine 123 or a Mitotracker. Mitochondrial proliferation was assessed after pulse labeling with BrdU. The involvement of the cytoskeleton in the segregation process was determined by drug action. The teloplasms form during the first interphase as consequence of a 3-step sequential process of mitochondrial redistribution throughout the egg cytoplasm. The first step is a microtubule dependent process of ectoplasm thickening due to centrifugal mitochondrial transportation from the neighboring endoplasm. During the second step mitochondria move in the plane of the ectoplasm to become concentrated at the wall of rings (polar rings) and bands of contraction. This process appears to mostly depend on actin. The furrowing pattern of the egg during this step can be modified by cold treatment and seems to be determined during oogenesis. During the third step the ectoplasm flows to either of the poles in conjunction with bipolar displacement of the polar rings and shortening of the contraction bands. This step depends on both microtubules and microfilaments. Mitochondria of first interphase eggs have three special features: (1) they move in clusters, (2) their movement depends on both microtubules and microfilaments and (3) they proliferate continuously. During the first interphase the polarized meiotic egg becomes a bipolar cell.

Actins↗

PubMed1993

[Microdoses of BCG vaccine for prophylaxis in bladder cancer stage T1].

A prophylaxis with a minidose of BCG Vaccine (1 mgr.) is performed in vesical instillation during one year, to 108 patients bearing bladder cancer in the stage T1. In the first month the instillations are once a week, each fifteen days the second and third month and then, once a month for one year. An 19.4% of recurrences is obtained with an general average observation time of 37.3 months as well as an important increase of muster populations of T lymphocytes and a positive test of dinitroclorobenzene. As complications we have obtained an inguinal BCG adenitis and in a few cases disury and frequency for two or three days. We conclude that the doses of the BCG vaccine used during the period of one year, is satisfactory in the reduction of recurrences and without important complications.

Administration, Intravesical↗

PubMed1992