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Biomedical subjects

M Mena

Publications and source records attributed to M Mena.

At least 37 records · Page 2Linked to original sources
PubMed1992

Homologous sucrose synthase genes in barley (Hordeum vulgare) are located in chromosomes 7H (syn. 1) and 2H. Evidence for a gene translocation?

The chromosomal location of the two types of sucrose synthase genes, Ss1 and Ss2, has been investigated in barley by Southern blot analysis of wheat-barley addition lines using non-cross-hybridizing-specific probes corresponding to the C-terminal regions of their respective cDNA clones (congruent to 250 bp). The Ss1 gene, whose cDNA of 2,667 bp has been entirely sequenced, is located in the beta-arm of chromosome 7H (syn. 1), while that corresponding to the homologous Ss2 is in the short arm of 2H, suggesting the existence of a translocation event between these two chromosomes in cultivated barley after an initial gene duplication and divergent evolution.

Amino Acid Sequence↗
PubMed1992

A major barley allergen associated with baker's asthma disease is a glycosylated monomeric inhibitor of insect alpha-amylase: cDNA cloning and chromosomal location of the gene.

A 14.5 kDa barley endosperm protein that is a major allergen in baker's asthma disease, as previously shown by both in vitro (IgE binding) and in vivo tests, has been identified as a glycosylated monomeric member of the multigene family of inhibitors of alpha-amylase/trypsin from cereals. A cDNA encoding this allergen (renamed BMAI-1) has been isolated and characterized. The deduced sequence for the mature protein, which is 132 residues long, is identical in its N-terminal end to the 20 amino acid partial sequence previously determined from the purified allergen, and fully confirms that it is a member of the multigene family of cereal inhibitors. Southern-blot analysis of wheat/barley addition lines using the insert in the BMAI-1 cDNA clone as a probe, has led to the location of the allergen gene (Iam1) in barley chromosome 2, while another related member of this protein family, the barley dimeric alpha-amylase inhibitor BDAI-1 gene (Iad1) has been located in chromosome 6. Iam1 is the first member of this inhibitor family in cereals to be assigned to chromosome group 2, thus extending the dispersion of genes in the family to five out of the seven homology groups of chromosomes in wheat and barley (chromosomes 2, 3, 4, 6 and 7).

Air Pollutants, Occupational↗
PubMed1992

Age-related capacity of neuroendocrine factors to differentiate T cells in vitro.

The present report shows the capacity of hypothalamic extract (HE) to differentiate bone marrow cells to Thy-1+ cells in vitro. A two-step short-term culture was used. In the first step thymus and pituitary were co-cultured in the presence of HE. Supernatant was then transferred to a bone marrow cell suspension and following a period of culture, the percentage of Thy-1+ cells was determined by a microcytotoxicity assay. Results indicated that: (a) HE from young mice show a very efficient differentiating capacity; (b) HE from young mice is equally efficient when old pituitary, thymus and marrow are used; (c) HE from old donors has no capacity to differentiate T cells; (d) there is a progressive age-related decline of this capacity; and (e) there is a feed-back mechanism involved in this process. It is concluded that hypothalamic factors can regulate the differentiation of T cells and that this effect operates through a mechanism involving pituitary and thymus.

Aging↗
PubMed1991

[Physiopathology of dystonia].

Dystonia is a movement disorder characterized by sustained twisting movements and muscle contractions and abnormal postures. Dystonia is a symptom present in many diseases of the central nervous system. Anatomical data reveal that dystonia appears in diseases involving the basal ganglia, diencephalon, brain stem and cerebellum. Physiological studies revealed an abnormal facilitation of polysynaptic reflexes at the brain stem level. A common pathogenic mechanism for dystonia must be found in order to delineate in effective treatment. From clinical and biochemical data we suggest that dystonia is produced by abnormal shift of the norepinephrine/dopamine neurotransmission in favor of norepinephrine in different brain areas.

Animals↗
PubMed1991

Experimental autoimmune thyroiditis. II. An immunocytochemical and ultrastructural study of the lesion.

The early steps of thyroid damage in experimentally induced autoimmune thyroiditis in mice were studied. Mice were immunized with 150 micrograms of rat thyroglobulin followed by 20 micrograms of bacterial LPS 3 h later on day 0 and 7. Thyroid glands were obtained on days 14, 21 and 28 in order to be studied by light microscopy, electron microscopy and immunocytochemical techniques. The initial lesion was a focal inflammatory infiltrate composed of lymphocytes and lymphoblasts, and plasma cells as the damage progressed. In some cases an increase in neutrophils, macrophages and eosinophils was also seen. The infiltrate became multifocal and eventually diffuse and in few cases germinal center-like structures were seen. The cellular infiltrate corresponded to IgG, IgM and IgA bearing B cells and to a lesser degree Thy 1.2, Lyt 1 and Lyt 2 bearing T cells. Follicular alterations corresponded to different degenerative states of the follicular cells that in some cases was seen without the participation of lymphoid cells. Another mechanism observed was the migration of small lymphoid cells and plasma cells between the follicular cells.

Animals↗
PubMed1990

Cloning of cDNA and chromosomal location of genes encoding the three types of subunits of the wheat tetrameric inhibitor of insect alpha-amylase.

We have characterized three cDNA clones corresponding to proteins CM1, CM3 and CM16, which represent the three types of subunits of the wheat tetrameric inhibitor of insect alpha-amylases. The deduced amino acid sequences of the mature polypeptides are homologous to those of the dimeric and monomeric alpha-amylase inhibitors and of the trypsin inhibitors. The mature polypeptides are preceded by typical signal peptides. Southern blot analysis of appropriate aneuploids, using the cloned cDNAs as probes, has revealed the location of genes for subunits of the CM3 and of the CM16 type within a few kb of each other in chromosomes 4A, 4B and 4D, and those for the CM 1 type of subunit in chromosomes 7A, 7B and 7D. Known subunits of the tetrameric inhibitor corresponding to genes from the B and D genomes have been previously characterized. No proteins of this class have been found to be encoded by the A genome in hexaploid wheat (genomes AA, BB, DD) or in diploid wheats (AA) and no anti alpha-amylase activity has been detected in the latter, so that the A-genome genes must be either silent (pseudogenes) or expressed at a much lower level.

Amino Acid Sequence↗
PubMed1990

[Progeny in women with fetal alcohol syndrome].

Among children referred to our genetic clinics for mental or growth retardation we identified 8 of their mothers with the fetal alcohol syndrome. This was complete in 5 and partial in 3. All of their alcoholic mothers had died. Most of the patients were unwed mothers with mental retardation and no elementary education. One of them was also alcoholic and her third offspring had the syndrome. The etiology of this syndrome and possible preventive measures are discussed.

Adult↗
PubMed1989

Experimental autoimmune thyroiditis. I. Participation of IgA, IgM and IgG in the development of the disease.

Many factors have been shown to be important in the pathogenesis of experimentally induced autoimmune thyroiditis (EAT) in mice. However, the role of thyroid antibodies has not been clearly established. EAT was induced with rat Tg + LPS in RK mice. Two injections were given i.v. on days 0 and 7 and the antibody titre against rat and syngeneic Tg was determined in the weeks thereafter. Determination of the cellular infiltration of the thyroid, the presence of IgA, IgG and IgM in thyroid sections and electron microscope analysis of electro-dense deposits were also undertaken. Results show that (1) RTg + LPS is a potent inducer of autoimmunity with high antibody titer to RTg and MTg and 100% of the mice showed some degree of thyroid infiltrate on days 21 and 28; (2) immunofluorescence staining revealed that initially IgM is the main immunoglobulin and is later replaced by IgG. IgA is constantly present throughout the experimental period; (3) electro-dense deposits were found almost exclusively between the capillary basement membrane and the follicular basement membrane.

Animals↗
PubMed1986

Neuroendocrine regulation of thymus hormones: hypothalamic dependence of "facteur thymique serique" level.

The influence of the hypothalamus extract (HE) on the blood level of the "facteur thymique serique" (FTS) was studied. Hypothalami collected from young mice were pooled, homogenated in saline, and centrifuged; finally, the supernatant injected in old or thymectomized mice with no detectable levels of FTS. In the old mice the treatment results in a reappearance of this circulating thymic hormone; in contrast, in adult thymectomized animals, the HE injection was not able to induce FTS activity. When HE donors were pretreated with thymosin fraction 3, known to contain FTS among other active peptides, the capacity of such a hypothalamus preparation to induce reappearance of FTS in old animals is greatly diminished. The data presented here suggest that the capacity of the thymus to secrete FTS depends on a hypothalamic factor, and therefore the absence of this thymic hormone in the aged reflects a failure of the thymus linked to its impaired neurologic control. On the other hand it seems evident that a feedback system operates in order to regulate the release of this hypothalamus stimulatory factor.

Animals↗
PubMed1982

Effects of thyroid hormone on some uterine responses to estrogen.

Uterine edema induced by 0.1 microgram 17 beta-estradiol (E2)/100 g BW, as well as uterine eosinophilia induced by 0.01, 0.1, 1, 10, and 30 micrograms E2/100 g BW, decrease in the presence of 20 micrograms T3 or T4/100 g BW in the immature rat. Estrogen binding by uterine eosinophils and the number of eosinophils in the blood also decrease with T3 or T4, suggesting an explanation for the findings in the uterus. Thyroid hormones alone or in the presence of 0.001, 0.01, 0.1 and 1 microgram E2/100 g BW, increase the uterine RNA content 7 h after administration compared with the same doses of E2 alone. This response is not associated with any further increase in the urine protein content. The results show a dissociation between the effects of estrogen on RNA or protein levels, which are decreased by thyroid hormones, and some early estrogenic responses (uterine edema and eosinophilia), which are decreased by thyroid hormones.

Animals↗
PubMed1982

Autoimmune thyroiditis in young and old mice: differential effect of high doses of PHA.

Experimental autoimmune thyroiditis (EAT) was used to study the effect of age and PHA in the autoimmune response. EAT was induced in mice by two injections 7 days apart of soluble syngeneic mouse thyroglobulin (MTg) and lipopolysaccharide (LPS) as adjuvant. Thereafter the antibody titre to MTg was determined in the serum and the degree of cellular infiltration estimated in thyroid sections. The results show that in old mice the humoral response is low and no cellular infiltration is found in the thyroid; young mice showed both types of immune response. Phytohaemagglutinin (PHA) was shown to inhibit antibody production when given before the first and second antigen injection, and to suppress completely the cellular immunity against thyroid tissue. When given to old mice a reduction in anti-MTg titre is also seen, but no effect on infiltration is found. However when PHA is only given before the second dose of antigen a stimulation of cellular immunity is seen in contrast to young mice where there is no effect.

Aging↗