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Biomedical subjects

M Freire

Publications and source records attributed to M Freire.

At least 37 records · Page 2Linked to original sources
PubMed1990

Study of Golgi-impregnated material using the confocal tandem scanning reflected light microscope.

The tandem scanning reflected-light microscope (TSM) is a real-time, direct-view confocal microscope. Only those points in the specimen situated in the focal plane contribute information to the image. A Tracor Northern TMS with piezo-electric control of the objective lens was used to generate 3-D images from Golgi-impregnated hamster cerebral cortex. Stereoscopic pairs of images were recorded as 35-mm colour film transparencies by photographing while automatically through-focusing along inclined axes. Transferring the image via a TV camera to the computer, stereo-pairs were obtained by oblique through-focusing and summing, displaying maximum intensity data in each line of sight. Pseudocolour topographic displays were generated by assigning the pixel value in a zeta map image as the focal depth at which the back-scattered light signal was maximal. The TSM was also modified so that a conventional transmitted-light image with a large depth of field could be obtained simultaneously as the very shallow depth of field confocal back-scattered-light image seen at any focus level. The conventional image is a silhouette of the impregnated neurons: the top surface of the cell is not visible and the relationships of processes that cross over cell bodies cannot be discerned. TSM gives a high-contrast image. The Golgi precipitate over the neuronal surface is resolved as globular or ovoid, coloured particles. The smaller particles also cover the dendritic spines. All the confocal range (extended focus) image display methods satisfactorily demonstrated the 3-D arrangement of cell bodies and processes in the chosen volume.

Animals↗
PubMed1990

Women as victims of torture.

This is a retrospective study on the effects of torture on Latin American refugee women in Toronto. Thirty-six cases of female torture victims are reviewed. The cases are divided in 2 groups, according to whether they experienced physical and psychological torture or only psychological assaults. Both groups are compared in terms of demographic characteristics, social and/or political involvement prior to the traumatic experiences, symptoms for which they sought psychiatric intervention and recovery rates. The symptoms presented by all women are consistent with those described in the literature for torture victims, regardless of their sex. The main findings are that women who experienced direct physical and psychological violence more frequently had persistence of symptoms than women who experienced only psychological violence.

Adolescent↗
PubMed1989

Thymosin-beta 4 gene. Preliminary characterization and expression in tissues, thymic cells, and lymphocytes.

A cDNA for rat thymosin-beta 4 was used to investigate the expression of this gene in different tissues, thymic cells, and lymphocytes. Hybridization analysis of total RNA from 13 rat tissues demonstrated the presence of an 800 nucleotides-long mRNA in all the tissues surveyed, with the highest levels in spleen, thymus, and lung. Examination of thymic cells showed that the thymosin-beta 4 gene is predominantly expressed in thymocytes. The thymosin-beta 4 mRNA was also studied in Ig+ and Ig- lymphocytes, being fourfold more abundant in Ig- than Ig+ splenic lymphocytes, whereas similar levels were found in both types of blood cells. The analysis of RNA from T cells at different maturation stages evidenced slight differences in their thymosin-beta 4 mRNA content, indicating that thymosin-beta 4 gene expression is not clearly related to the differentiation process of T cells. All these results do not support the roles for thymosin-beta 4 in cellular immunity and differentiation of lymphoid cells, suggesting a more general function for this peptide. Preliminary characterization of the human beta 4 gene by restriction analysis disclosed a complicated pattern consistent with multiple genes and/or introns. The analysis of genomic DNA from different species ranging from humans to Escherichia coli showed that this gene is only highly conserved in mammals.

Animals↗
PubMed1989

The expression of prothymosin alpha gene in T lymphocytes and leukemic lymphoid cells is tied to lymphocyte proliferation.

We isolated the cDNA for human prothymosin alpha (ProT alpha) from a human peripheral T-cell library using two synthetic oligonucleotides as probes. Hybridization studies with this cDNA showed that the ProT alpha mRNA is detectable in all the rat tissues studied but is most abundant in thymus and within this gland mainly synthesized by thymocytes. In the T-cell lineage, its expression is higher in proliferative immature thymocytes than in pre- and post-thymic T lymphocytes. A quite similar pattern was obtained with the proliferation-related protein proliferating cell nuclear antigen/cyclin. These data show that ProT alpha mRNA levels change with the maturation stage of T-cells. Moreover, the amount of ProT alpha transcript is increased in lymphocytes from human patients with leukemias. Our findings indicate a role for ProT alpha linked to lymphocyte proliferation.

Amino Acid Sequence↗
PubMed1989

Purification and characterization of a cofactor that controls the oxidative phase of the pentose phosphate cycle in liver and other tissues of rat.

We have recently reported the presence, in rat liver, of a cofactor characterized as a protein of Mr 10(5), which cooperates with GSSG to prevent the inhibition of glucose-6-phosphate dehydrogenase by NADPH. The inhibition that this coenzyme also exerts on 6-phosphogluconate dehydrogenase is similarly prevented by a cofactor-GSSG system. The activity of the cofactor increases in the livers of rats fed on carbohydrate-rich diets. Purification of the components in rat liver homogenate by ion-exchange chromatography and preparative polyacrylamide gel electrophoresis showed that the deinhibitory effect on both dehydrogenases is exerted by the same cofactor. The purified cofactor appeared as a unique protein of Mr 37.10(3) in SDS-polyacrylamide gel electrophoresis. Rat kidney and adipose tissue were the only nonhepatic tissues showing a cofactor-GSSG deinhibitory effect on both dehydrogenases of the oxidative phase of the pentose phosphate cycle. The deinhibitory activity, also corresponding with a cellular component of Mr 10(5), was only diet-inducible in adipose tissue. The neutralization of the kidney and adipose tissue deinhibitory activity by rat liver cofactor antibodies suggested that there was a structural relationship between the cofactors prepared from these tissues.

Adipose Tissue↗
PubMed1989

Synthesis and apparent secretion of prothymosin alpha by different subpopulations of calf and rat thymocytes.

Prothymosin alpha (ProT alpha), a polypeptide containing the sequence of thymosin alpha 1 (T alpha 1) at its NH2-terminus, has been isolated from calf thymocytes in a concentration in the order of that found in the whole thymic gland. As deduced from the analysis of their tryptic peptides, calf ProT alpha differs from the rat polypeptide at least in an alanine residue replacing valine at position 92. Thymocytes cultured in a radioactive medium exhibit an important secretory activity, ProT alpha being one of the products synthesized and exported to the culture medium. Large and small thymocyte subpopulations from calf and rat differ in their capacity to synthesize ProT alpha. The polypeptide is produced in a major concentration by large thymocytes. However, all the calf and rat thymocyte subpopulations show a similar capacity to secrete ProT alpha, the amount of the newly synthesized polypeptide recovered from cell culture supernatants being 80-90% of that found in thymocyte extracts.

Animals↗
PubMed1988

Quantitative computer analysis of Golgi-impregnated neurons using a new 'expanded stick' model for coding; its application to the study of axons.

A computer program to obtain quantitative data from an expanded 'stick model' of the Golgi-impregnated neuron is described. The computer program allows complete three-dimensional morphometric analysis of neurons, including the size of varicosities and spines and their distribution on neuronal branches. Furthermore, the perimeter and area of the perikaryon as well as the length, width and area of neuronal processes can be obtained. The use of this computer program is illustrated by coding two types of axons.

Animals↗
PubMed1987

An "expanded stick" model for coding Golgi-impregnated neuronal morphology.

A new model for coding Golgi-impregnated neuronal morphology, which can be implemented in any computer-assisted optical microscope, is described. This model, in addition to storing the three-dimensional coordinates of the selected neuronal points and their topological identifiers, codes for "width", "nature", and "shape". The "width" code digitizes the width of a neuronal process. The "nature" code can identify structures such as perikaryon, axon, apical dendrite, basal dendrite, etc. The "shape" code defines nodules and spines. Computer graphics routines are described for drawing nodules and spines as well as neuronal processes with "width".

Animals↗
PubMed1987

A simple procedure for large-scale purification of plasmid DNA.

We report a simple, rapid and reliable procedure for large-scale purification of plasmid DNA from non-amplified bacterial cultures. It is a modification of the boiling method of Holmes and Quigley [Anal. Biochem. 114 (1981) 193-197] and involves gel-filtration chromatography using Sephacryl S-1000 for final purification of plasmid DNA. This method does not require CsCl gradients and the recovered plasmids are free of RNA and chromosomal DNA, are supercoiled, retain their biological activity, and are suitable for restriction analysis.

Chromatography, Ion Exchange↗
PubMed1986

Regulation of the pentose phosphate cycle. Cofactor that controls the inhibition of glucose-6-phosphate dehydrogenase by NADPH in rat liver.

A cofactor of Mr 10(4), characterized as a polypeptide, was found to co-operate with GSSG to prevent the inhibition of glucose-6-phosphate dehydrogenase by NADPH, in order to ensure the operation of the oxidative phase of the pentose phosphate pathway, in rat liver [Eggleston & Krebs (1974) Biochem. J. 138, 425-435; Rodriguez-Segade, Carrion & Freire (1979) Biochem. Biophys. Res. Commun. 89, 148-154]. This cofactor has now been partially purified by ion-exchange chromatography and molecular gel filtration, and characterized as a protein of Mr 10(5). The lighter cofactor reported previously was apparently the result of proteolytic activity generated during the tissue homogenization. The heavier cofactor was unstable, and its amount increased in livers of rats fed on carbohydrate-rich diet. Since the purified cofactor contained no glutathione reductase activity, the involvement of this enzyme in the deinhibitory mechanism of glucose-6-phosphate dehydrogenase by NADPH should be ruled out.

Animals↗
PubMed1986

The distribution of N-acetyl-beta-glucosaminidase, beta-glucuronidase, acid alpha-naphthyl acetate esterase and alpha-naphthyl acetate esterase in subpopulations of thymocytes, bone marrow cells and other lymphoid organs in mice.

Thymocytes, bone marrow lymphocytes, as well as lymphocytes from spleen, lymphoid nodes and peripheral blood were obtained from BALB/c mice. Subpopulations of BALB/c bone marrow T-lymphocyte precursors and immature (small) and mature (large) thymocytes, as established by the percentage of terminal deoxynucleotidyl transferase (TdT) and peanut agglutinin (PNA) positive cells, were obtained by centrifugation on discontinuous density gradients. The activities of N-acetyl-beta-glucosaminidase (NAG), beta-glucuronidase (BG), acid alpha-naphthyl acetate esterase (ANAE) and alpha-naphthyl acetate esterase (NAE) were determined by enzymatic assays of cell extracts of the diverse T-lymphocyte subpopulations, in order to follow their evolution with the maturation of the T-lymphocytes in the thymus. These activities were compared with that determined in lymphocytes from spleen, lymphoid nodes and peripheral blood. The glucidases BG and NAG and the esterases ANAE and NAE present a high decrease in their activities from bone marrow T-lymphocyte progenitors to immature thymocytes. BG, NAG and ANAE activities undergo an about 3-fold increase with the evolution of the thymocytes from small to large cells. Whereas the level of the NAE activity decreases (2-fold) with that evolution of the thymocytes. Lymphocytes from spleen and lymphoid nodes exhibit activities of the glucidases and, specially, the esterases marked by higher than those of thymocyte populations. Peripheral blood lymphocytes also present NAG, ANAE and NAE activities higher than in thymocytes, but their BG activity is lower.

Animals↗
PubMed1986

An inexpensive and interactive microcomputer system for codifying Golgi-impregnated neuronal morphology.

An interactive microcomputer system has been developed for the quantitative analysis of Golgi-impregnated neuronal morphology (GINM). The system uses commercially available hardware: a 48K RAM microcomputer (Apple II), a TV monitor (NEC), an optical microscope (Reichert Biovar) with a camera lucida and a specially developed wheel attached to the focus adjustment knob and to a digital planimeter (Tamaya), allowing one to obtain the value of the z-coordinate. The x- and y-coordinates are obtained using the movement of a point plotted by the computer on the TV monitor. This point is superimposed upon the GINM point to be codified employing the camera lucida. The x- and y-coordinates are acquired automatically while the variations of the z-coordinate are introduced by the computer keyboard. The three-dimensional coordinates of the selected GINM points and different codes are stored by the computer in a six-dimensional array. The software is written in BASIC. The results demonstrate that the digitization and quantitative analysis of GINM can be achieved with reasonably inexpensive equipment.

Animals↗
PubMed1985

Evidence for the synthesis of thymosin alpha 1 by calf thymocytes and the production of this peptide by natural processing.

Thymus and thymocytes from calf were extracted under isotonic conditions in the presence of protease inhibitors or under severe denaturing conditions (after quick freezing and thawing in boiling 0.1 M NaCl). The extracts, as well as the medium in which the thymocytes were obtained from thymus fragments (thymocyte supernatants), were size-fractionated by ultrafiltration. As in whole thymus isotonic extracts, thymosin alpha 1 [A. L. Goldstein, T. L. K. Low, M. McAdoo, J. McClure, G. B. Thurman, J. Rossio, C-Y. Lai, D. Chang, S-S. Wang, C. Harvey, A. H. Ramel, and J. Meienhofer (1977) Proc. Natl. Acad. Sci. USA 74, 725-729] was contained in isotonic extracts from thymocytes and also in thymocyte supernatants, as determined by isoelectric focusing and reverse-phase HPLC analysis. The extraction under denaturing conditions mainly yielded products with molecular masses over 50,000, showing very similar isoelectric focusing patterns in both thymocytes and whole thymus extracts. As deduced by isoelectric focusing analysis of diverse size-fractionated products, a strong association capacity seems to be responsible for an apparently high molecular mass of the components of these extracts. According to the pI, two of these components were prothymosin alpha [A. A. Haritos, G. J. Goodall, and B. L. Horecker (1984) Proc. Natl. Acad. Sci. USA 81, 1008-1011] and thymosin alpha 1. Prothymosin alpha was not detected in any isotonic extracts or thymocyte supernatants. These data suggest that calf thymocytes are capable of producing thymosin alpha 1, which would arise by natural processing of its precursor.

Animals↗
PubMed1985

Characteristics of the translation of thymosin alpha 1 precursor mRNA by cell-free wheat germ system. Evidence for the acetylation of thymosin alpha 1 precursor.

At the optimal concentrations of Mg2+ and K+ to translate total thymus PolyA+-RNA, the purified thymosin alpha 1 precursor mRNA saturate the protein synthetic activity at lower concentration than the total thymus mRNAs. The polyamine spermidine increases the translation rate of the messenger, which is modulated by magnesium, rather than improve the yield in full-length chains of thymosin alpha 1 precursor. As other eukariotic mRNAs, this messenger presents the "cap" modification at the 5'-end terminal position. The incorporation of [3H]acetate into the translation product of the messenger, shows an evidence for the acetylation of the thymosin alpha 1 precursor during its biosynthesis in vitro.

Acetylation↗
PubMed1984

The distribution of adenosine deaminase, purine nucleotide phosphorylase and 5'-nucleotidase in subpopulations of thymocytes, bone marrow cells and other lymphoid organs in mice.

Lymphocyte populations of BALB/c mice were obtained from bone marrow, thymus, spleen, peripheral blood and lymphoid nodes. Subpopulations of thymocytes and bone marrow T-lymphocyte precursors were separated by density gradient centrifugation. The activity of adenosine deaminase (ADA) undergoes a marked increase during the evolution of bone marrow T-cell precursors to immature thymocytes, and a decrease with thymocytes maturation. The peripheral blood lymphocytes (PBL) present the lower activity of the enzyme, and lymphocytes from spleen (SL) and lymphoid nodes (LNL) show activity in the order of that in mature thymocytes. The activity of purine nucleotide phosphorylase (PNP) in the different lymphocytes populations experiments a very little variation with the T-lymphocyte differentiation. With the evolution of T-lymphocyte precursors to immature thymocytes the 5'-nucleotidase (5'-NT) activity experiment a 2-fold decrease. The thymocytes maturation is correlated with an increase in the activity of 5'-NT. The PBL present the maximal activity of the enzyme, whereas in spleen and LNL its levels of activity are in the range of that in mature thymocytes and bone marrow T-cell precursors respectively.

5'-Nucleotidase↗
PubMed1983

Synthesis of thymosin alpha 1 precursor cDNA and purification of active mRNA by affinity chromatography.

1. Thymosin alpha 1 precursor [3H]cDNA-cellulose synthesis was carried out by reverse transcription with RNA-dependent DNA polymerase from avian myeloblastosis virus using oligo(dT)-bound to cellulose as a primer. 2. Unlabelled thymosin alpha 1 precursor cDNA-cellulose was synthetized in a preparative scale to be used in affinity chromatography. 3. Poly(A)-mRNA from calf thymus was subjected to cDNA-cellulose affinity chromatography and an active messenger obtained in a yield of 3% respect to the total thymus poly(A)-mRNA chromatographied. 3. The analysis of the translation products of the purified mRNA have shown it as the thymosin alpha 1 precursor messenger.

Animals↗
PubMed1982

Co-therapy in a clinic for schizophrenia.

In the outpatient treatment of schizophrenia, the routine practice of providing each patient with two co-therapists results in several benefits: reduced dependency, increased expertise, objective monitoring, added support and morale for the therapists, more obvious and therefore more reversible countertransference, more obvious and therefore more treatable "splitting" and "projecting." Despite these benefits, problems arise in the two-therapist arrangement. They are discussed under the following headings: loyalty conflicts; limit setting; crisis management; family work. The authors report on techniques of co-therapy problem prevention and problem resolution. Though not always successful, co-therapy continues to be a useful model of service delivery to schizophrenic outpatients.

Ambulatory Care↗