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Biomedical subjects

A Cano

Publications and source records attributed to A Cano.

At least 181 records · Page 10Linked to original sources
PubMed1987

Spectroscopic studies on the structural organization of the lectin discoidin I: homologies with fibronectin.

The structure of the lectin discoidin I has been studied by circular dichroism and fluorescence spectroscopy. A positive ellipticity band at 224 nm is detected in the CD spectrum of discoidin I. The fluorescence spectra show a defined shoulder at 325 nm that through acrylamide quenching has been associated with a displaced tryptophan residue partly buried in the discoidin I molecule. This tryptophan could also be responsible for the 224 nm positive band of the CD spectrum. These spectroscopic characteristics of discoidin I indicate the existence of structural homologies with fibronectin, where the optical activity of aromatic chromophores has been associated with the positive ellipticity band at 227 nm. The CD adjust parameters and theoretical secondary structure predictions show that discoidin I is a molecule with a low content of alpha-helix and beta-strand and high content of beta-turn structures, similar to other lectins.

Circular Dichroism↗
PubMed1987

Biochemical and morphological effects of sodium butyrate on Dictyostelium discoideum development.

Pretreatment of proliferating D. discoideum amoebae with 10 mM butyrate for at least 8 h (one duplicating time) induced a reversible and dose dependent premature expression of several developmental parameters when the cells were starved in the absence of the fatty acid. The aggregative phase of the morphogenetic cycle was reduced in 2 h and the appearance of mature fruiting bodies and spores took place 4 h earlier as a result of butyrate pretreatment. Some developmentally regulated proteins, such as contact-sites A, cell surface lectins and cyclic AMP phosphodiesterase were also expressed 2 h earlier in butyrate pretreated cells than in controls. The level of extracellular cyclic AMP was reduced in butyrate pretreated cells, while other parameters of cyclic AMP metabolism were not affected. Butyrate also caused a partial inhibition of growth and the hyperacetylation of histone H4 in growing amoeba. These results suggest that butyrate acts as an inducer of differentiation in D. discoideum and can therefore be used as an experimental tool in order to explore regulatory mechanisms operating in slime mold differentiation.

Acetylation↗
PubMed1986

Immunological probes for oestradiol receptors in human breast tumours.

Monoclonal antibodies have been prepared against a soluble oestradiol receptor (REC) preparation partially purified from human myometrium by oestradiol affinity chromatography. The antibodies were detected by their ability to immunoprecipitate receptor bound [125I] oestradiol. One of the antibodies (D5) has been studied in detail. It will only precipitate REC after activation by salt, heat, low pH or KCNS and will not react with nuclear RE. It will not react with androgen, progesterone or glucocorticoid receptors nor with sex hormone binding globulin; it will only combine with REC from human sources. D5 recognizes a cytoplasmic 29 kdalton protein (p29) that can be separated from both type I and II soluble oestradiol binding proteins. p29 can react with activated REC and is qualitatively and quantitatively related to REC. IRMA and histochemical methods have been developed for quantitating p29 and relating its amount to receptors in human breast tumours. With both methods, highly significant (P less than 0.001) correlations with REC but not RP have been obtained. Both methods indicate that many REC-RP+ tumours contain p29. The histochemical method detects marked cellular heterogeneity in some tumours. The function of p29 is not known. It is an REC-related antigen that may be a previously undetected component of the oestradiol receptor machinery.

Antibodies, Monoclonal↗
PubMed1986

Cytoplasmic and nuclear estrogen binding capacity in the rat uterus during treatment with danazol and testosterone.

Danazol, testosterone and dihydrotestosterone (DHT) were tested as competitors for estrogen receptors on immature rat uterus cytosol. No competitive binding could be demonstrated for any of these steroids. After that, prepubertal Wistar rats were exposed to danazol, testosterone or propylene glycol (control) for 3 days or 17 days. After the appropriate exposure to medication, the animals were killed. Both danazol and testosterone appeared to be uterotropic after 3 days of treatment, although the increase in the uterine weight was significant only in the danazol-treated group (p less than 0.05). This effect was lost after 17 days of treatment. Estradiol receptor binding assays were done on the cytosolic and nuclear fractions of the homogenized uterine tissue of each group. The estrogen binding capacity of cytosols was increased in both the danazol (p less than 0.05) and the testosterone (p less than 0.01) groups after 3 days of treatment. A parallel increase was found in the nuclear fraction of both groups. After 17 days of treatment, the comparison between the 3 groups showed no differences in the cytosolic or nuclear estrogen binding capacity. The information provided by this study suggests that some effects of danazol may be due to an androgenic action and that may be associated to increases in the free fraction of testosterone.

Animals↗
PubMed1986

The positive feedback of estradiol on gonadotropin secretion in women with perimenopausal dysfunctional uterine bleeding.

The functionality of the hypothalamic-pituitary-ovarian axis was explored in 27 women with perimenopausal dysfunctional uterine bleeding. The positive feedback effect of estradiol on LH and FSH was studied by the estrogen challenge test, which was performed by a single i.m. injection of estradiol benzoate. An early decline of both LH and FSH was followed by an increase of LH, mainly due to the cases in which the estrogen test was positive. FSH remained low through the whole period tested. The results were compared with those found in 5 normal menstruating women. The frequency of positive estrogen tests, defined by an acute estradiol-induced discharge of LH, was lower in the perimenopausal patients (P less than 0.025). The results of the tests used in our study showed an impairment of the positive feedback system in the perimenopausal-dysfunctional-bleeding group.

Estradiol↗
PubMed1986

Relationship of maternal glycosylated hemoglobin and fetal beta-cell activity with birth weight.

A population of 40 mother-newborn pairs with a wide range of birth weight has been studied. Seventeen of the mothers were diabetic, while the other 23 were normal pregnant women. The chronic blood glucose levels were assessed in the mothers through the percentage of glycosylated hemoglobin (HbA1) at delivery. The functional activity of the pancreatic beta-cells in the newborns was estimated through the concentration of insulin and C-peptide in the cord blood. Maternal HbA1 was not quantitatively related to the birth weight ratio. In contrast, both insulin and C-peptide correlated significantly with it. Is is concluded that in populations with a good metabolic control, blood glucose levels, as measured by HbA1, are not the major determinant of fetal growth.

Birth Weight↗
PubMed1986

Histochemical studies with an estrogen receptor-related protein in human breast tumors.

The histochemical characteristics of a Mr 29,000 phosphoprotein related to estradiol receptor are described in a large series of human breast tumors. The antigen was detected with a monoclonal antibody (D5) raised against partially purified human myometrial estradiol receptor. An indirect immunoperoxidase method was used with methacarn-fixed, wax-embedded sections. Quantitation of staining and its reproducibility are described. Results with trucut biopsies agree with those obtained with larger tumor sections. Normal breast is infrequently positive. Histochemical staining is higher in invasive carcinoma than in normal breast with ductal carcinoma in situ adjacent to infiltrating tumors exhibiting intermediate values. Furthermore, most in situ carcinomas have a heterogeneous staining pattern. About 20% of invasive tumors also exhibit heterogeneity. No simple correlation is seen between staining and histological grade. There are more low-staining tumors in young (less than 50 yr old) patients than in older women. Staining correlates with levels of cytosol estradiol receptor but not cytosol progesterone receptor. However, cytosol estradiol receptor-negative, cytosol progesterone receptor-positive tumors tend to have positive Mr 29,000 phosphoprotein levels. Positive staining is associated with a higher response rate to hormone therapy (50%). None of the negative tumors responded to hormone treatment. With these patients, comparison of histochemical assay for Mr 29,000 phosphoprotein and [3H]estradiol binding assays indicated that the former was at least as good as the latter assay in predicting hormone response. About 20% of cytosol estradiol receptor-positive tumors have low Mr 29,000 phosphoprotein, and such tumors have poor response to hormone treatment.

Adult↗
PubMed1985

Metabolic disturbances during intravenous use of ritodrine: increased insulin levels and hypokalemia.

The role played by insulin and the adrenergic system in the development of hypokalemia due to intravenous ritodrine has been evaluated. Fifteen women presenting with premature labor (group 1) were treated with ritodrine infusion, whereas seven pregnant women not in labor (group 2) were given 100 g glucose per os to induce hyperinsulinemia without participation of ritodrine. Serum glucose, insulin, potassium, sodium, chloride, and calcium were measured hourly. Whereas insulin levels were higher in group 2, potassium decreased markedly and significantly only in group 1. It is concluded that ritodrine-induced hypokalemia, that results partially from hyperinsulinemia, is mostly determined by other factors and is possibly a consequence of direct beta-adrenoceptor stimulation. Significant hypocalcemia of unexplained origin was observed with ritodrine.

Adult↗
PubMed1985

Effects of intravenous ritodrine on lactate and pyruvate levels: role of glycemia and anaerobiosis.

The role of glycemia in ritodrine-induced hyperlactatemia was assessed by measuring lactate and pyruvate levels and studying glycemia in patients treated with intravenous ritodrine for premature labor. Lactate levels were increased moderately by ritodrine and paralleled the levels of glucose; a similar parallelism also was observed in the glucose-administration group. Pyruvate levels also changed in proportion to lactate levels in this latter group, whereas in patients given ritodrine, pyruvate changed little and the lactate/pyruvate ratio was increased. These findings are discussed in terms of possible metabolic and vasopressor consequences of beta-adrenergic stimulation, with emphasis on the potential roles of increased glycemia and anaerobiosis.

Anaerobiosis↗
PubMed1984

Short term regulation by lysine of ornithine decarboxylase activity in Dictyostelium discoideum.

A transitory increase in ornithine decarboxylase activity has been observed soon after food removal from Dictyostelium discoideum amoeba. This increase can be prevented by supplementation of the differentiation buffer with the 11 amino acids known for their ability to retard the development of this slime mold. Lysine can replace the amino acid mixture with an apparent inhibition constant of 50 micromolar. This inhibition by lysine, which was only observed in vivo, took place within 5 min and was readily reversed upon lysine removal.

Amino Acids, Essential↗
PubMed1984

The role of membrane lectins in Dictyostelium discoideum aggregation as ascertained by specific univalent antibodies against discoidin I.

Antibodies against pure discoidin I have been used as a tool to ascertain the role of this lectin in aggregation of Dictyostelium discoideum. Discoidin I is widely expressed over the cell surface of aggregation-competent AX-2 cells, as ascertained by indirect immunofluorescence with specific (antidiscoidin I) antibodies. Univalent antidiscoidin I antibodies (Fab fragments) inhibit the aggregation-specific intercellular adhesion of D discoideum AX-2 cells in an in vitro assay. This inhibition depends on antibody concentration and cell density; a 50% inhibition of cell aggregation was obtained at antidiscoidin I Fab concentration of 4.5 mg/ml and 1 X 10(6) cells/ml. Aggregation and morphogenesis on solid support is also effectively inhibited when AX-2 cells are starved in the presence of antidiscoidin I Fab fragments. The inhibition of morphogenesis is also dose dependent and more effective than in the in vitro assay. No inhibition of aggregation either in the in vitro assay or on morphogenesis on solid support was observed with preimmune Fab fragments at any of the concentrations tested (up to 9.6 mg/ml).

Cell Aggregation↗
PubMed1984

Gonococcal perihepatitis: diagnostic and therapeutic value of laparoscopy.

Two patients with pelvic and right hypochondrial pain and with purulent vaginal exudate in which Neisseria gonorrhoeae was isolated, are presented. Laparoscopy was used in both cases. A diagnosis of perihepatitis was made by demonstrating the typical adhesions in "violin string" shape and by obtaining clinical improvement after breaking up those adhesions. Our conclusion is that laparoscopy is a useful diagnostic and therapeutic procedure in young women with pain in the right upper quadrant of the abdomen and with signs of lower genital infection.

Adult↗
PubMed1980

DNA-dependent transcription of adenovirus genes in a soluble whole-cell extract.

We have developed a cell-free system for studying the synthesis of mRNA in mammalian cells. The system consists of a dialyzed and concentrated whole-cell extract derived from HeLa cells, small molecules and cofactors needed for transcription, and exogenously added DNA. Accurate transcription by RNA polymerase II is entirely dependent upon addition of promoter-containing eukaryotic DNA. At optimal DNA and extract concentrations, transcription initiation from the adenovirus serotype 2 late promoter is readily detectable, and specific transcripts over 4000 nucleotides in length are observed. The RNA synthesized in vitro contains the same 5' capped RNase T1 undecanucleotide as does the in vivo transcript. RNA synthesis also initiates accurately at both an early and an intermediate adenovirus promoter site.

Adenoviruses, Human↗