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Biomedical subjects

L Calzada

Publications and source records attributed to L Calzada.

At least 19 recordsLinked to original sources
PubMed2001

Measurement of androgen and estrogen receptors in breast tissue from subjects with anabolic steroid-dependent gynecomastia.

In order to assess the relationship between anabolic steroid administration and gynecomastia, we studied the effects produced by administering nandrolone decanoate and a mixture of propionate, phenilpropionate, isocaproate and testosterone decanoate to bodybuilders during a six month period. The following significant changes occurred: a 53% reduction in serum testosterone; LH and FSH levels were suppressed to 77% and 87%, respectively, in comparison to control values; and although 45% of the subjects showed an increase in serum estradiol levels, no statistically significant differences were found compared with control estradiol levels. With regard to estradiol and androgen receptors, 85% of gynecomastia tissue contained estradiol or androgen receptors, while 40% contained both. The mean values of estradiol and androgen receptors in the cytosol were 65 +/- 10 and 52 +/- 5 fmol/mg protein, respectively. Nuclear androgen and estradiol receptor levels were 33 +/- 7 and 67.5 +/- 9 fmol/mg protein, respectively. The presence of hormone receptors in gynecomastia receptive cells provides support for the hypothesis that gynecomastia is steroid-dependent.

Adult↗
PubMed2001

In vitro cytotoxicity of flavonoids against MK2 and C6 tumour cells.

The cytotoxic effect of five flavonoids isolated from the aerial parts of the Asteraceae family of plants were studied in vitro using LLC-MK2 and C6 glial cells. Agehoustin A was shown to be cytotoxic for both cells (71% or 67% cell death). Agehoustin B and artemetin, which lack a methoxy group at C-8 (RI), were not cytotoxic for the cells (19% and 16% cell death). The three flavonoids showed considerable suppressive effects on LLC-MK2 and C6 cell growth. Lucidin-dimethylether and gnaphaliin were also not cytotoxic for cells but they had no suppressive effect on cell growth. The results show a structure-cytostatic activity relationship. We suggest that the methoxy group on C-8 and on the B ring are responsible for death cell.

Animals↗
PubMed2001

Hormone-related factors associated with hormone receptor levels in breast cancer.

Estrogen receptor (ER) and progesterone receptor (PgR) levels were determined in patients with a ductal infiltrating breast carcinoma. In premenopausal patients, the distribution of the PgR was higher than that of the ER. With increasing age of the patients, the concentration of the ER increased, whereas the PgR values showed an inverse relationship. According to the menstrual status, ER and PgR values were found to be higher in postmenopausal patients than in premenopausal ones. In relation to body fat distribution, in premenopausal patients the ER or PgR values were not found to be statistically significantly different (data no shown). In postmenopausal patients, the concentration of ER was diminished by 20% in patients with obesity of the upper body segment and by 40% in patients with obesity of the lower body segment as compared with the ER values of nonobese patients. While the PgR values diminished by 20% in patients with obesity of the lower body segment, in relation to PgR values of patients with obesity of the upper body segment, we found no statistically significant differences when compared with the PgR values of nonobese patients. With regard to the body mass index, this has remained constant in both types of body fat distribution. When body mass index values were compared with serum ER and PgR levels, no statistically significant differences were found.

Adult↗
PubMed1996

Estradiol and progesterone endometrial receptors and body fat distribution in obese women.

The content of endometrial receptors for estradiol (ER) and progesterone (PR) was determined in three groups (10 women each) classified with respect to body fat distribution: (1) normal, nonobese; (2) lower body segment obesity and (3) upper body segment obesity. The ER in group 3 were significantly (p < 0.05) higher than those of group 1. As regards PR, no statistical differences were found among the three groups. These findings demonstrate different endometrial ER concentrations in obese women according to body fat distribution, greater in upper segment obesity. Probably the lack of progesterone as well as other factors in the endocrine milieu of these patients may determine the differences found; therefore, future research on this matter should be carried out.

Adult↗
PubMed1996

[Receptor (ER, PgR) levels as prognostic factors in the endocrine therapy of pre- and post-menopausal patients with stage III infiltrative ductal and lobular cancer of the breast].

Receptors group (ER+, PgR+) in post-menopausal and pre-menopausal patients with ductal and lobular infiltrating mammary cancer clinical stage III and poorly differentiated histological assessment was studied. Levels of (ER+, PgR+) were correlated to endocrine therapy response (Tamoxifen) after 5 years of its administration. Both pre and post-menopausal patients with infiltrating ductal carcinoma, the (RE+, RPg+) tumour content, the mean values were 52 +/- 8, 53 +/- 11 fmol/mg protein and 111 +/- 20, 36 +/- 7 fmol/mg protein, respectively. With regard to lobular carcinoma, the (RE+, RPg+) tumour content, the mean value was 109 +/- 28, 46 +/- 12 fmol/mg protein in pre-menopausal patients, whereas it was 287 +/- 60, 66 +/- 18 fmol/mg protein in post-menopausal patients. The tumour was considered (ER+, PgR+) when specific binding was than 10 fmol/mg protein. In both ductal and lobular carcinoma the mean (ER+) concentrations are significantly different between the post and pre-menopausal patients, while the mean (PgR+) concentrations are significantly different in post-menopausal women. After five years of treatment with tamoxifen, survival analysis of patients with ductal infiltrating and lobular infiltrating carcinoma revealed a very strong correlation between levels of receptor group (ER+, PgR+) and their response to endocrine therapy.

Adult↗
PubMed1995

[Reductive effect of the sesquiterpenic lactone "Helenalin " and its metallic derivatives in the formation of the estradiol receptor complex in breast tumor tissue].

Chemotherapy for systemic therapy in breast cancer has been widely used, and has been supported by many varied compounds with different origins and different compositions. Nevertheless, all of them produce several side adverse effects which must be taken into account. For this reason we must study new possibilities in which the administered drug acts selectively on the tumour cell without injuring healthy tissue. For studying its effect, a gamma lactone called "Helenaline" and its metalic derivates He-Co, He-Hg and He-Cu were studied, which chemical composition allows them to react with -SH residues present in the tumour cell receptors, which when interspaced by a previous reaction, could modify its structural composition and finally its affinity by the hormone. The inhibition effect for formation of estradiol-receptor complex in breast tumour tissue using Helenaline 12 n M and 126 n M was studied, obtaining 14% and 56% inhibition effect respectively. When He-Co, He-Hg and He-Cu effect was studied, this effect was raised obtaining 11%, 10.5% and 60% with 12 nM and 44.5%, 74.4% and 86% with 126 nM respectively.

Antineoplastic Agents, Phytogenic↗
PubMed1993

[The role of estradiol and progesterone receptors in the selection of endocrine therapy fo patients with fibrocystic mastopathy].

Estradiol and progesterone receptors were analyzed in breast tissue of 100 women with mastopathy fibrocystic. Four groups were found according to the receptors detected: (R-E+, R-Pg+); (R-E+, R-Pg-); (R-E-; R-Pg+); (R-E-, R-Pg-). Ten percent were positive for both receptors, while 75 percent were negative for both estradiol and progesterone receptors. Ten percent were estradiol receptor positive (R-E+). Eight percent were progesterone receptor positive (R-Pg+). In this pathology type were considered "receptor positive" when specific binding was higher than 6 fmol/mg. protein. These "receptor positive" had specific binding in the range of 6.1-80 fmol/mg. protein and was considered "receptor negative" when specific binding was less than 6 fmol/mg. protein. While there was no correlation between the two receptors and patient age. We discuss the presence, type of estradiol and progesterone receptors for the hormonal treatment of patients with mastopathy fibrocystic.

Adult↗
PubMed1992

[Cholesterol and phospholipids in human seminal plasma before and after vasectomy].

Before and 2.6 months after vasectomy the alterations of secretory capacity and physiologic damage of the accessory genital glands, were evaluated by means of chemical analyses of certain constituents of seminal plasma such as free cholesterol, esterified cholesterol and phospholipids. The results of these studies showed that the ratio between the concentration of free cholesterol and esterified cholesterol is constant six months after vasectomy and the concentration of phospholipids decreases two months after vasectomy. These results are significant and may be important to know the alterations of secretory capacity of the human genital glands after vasectomy.

Cholesterol↗
PubMed1991

[The role of hyperpolarization and depolarization of the membrane of the human spermatozoon].

The electric potential across the membrane (psi) is evaluated through the accumulation of the lipophilic, radiolabelled, triphenylmethylphosphonium (3H-TPMP+), cation on membrane human sperm. The washed sperm cells, were incubated in presence of 3H-TPMP+ in low-K+ medium or high-K+ and allowed to take up the cation to steady-state (ie; 20 min at 37 degrees C). By using this differential, the value obtained was inserted in the Nernst equation, this value yielded a psi of -69 +/- 2 mV. The presence of divalent cations Zn++ and Mg++ in the incubation medium both induced a hyperpolarization of 10% and 8.6%, respectively. The addition of specific reagents such as p-chloromercuribenzene-sulfonate and ethylene-diamine-tetraacetic acid sodium salt both decreased the psi 35% and 58% respectively. The agents to act upon the components of the sperm cell membrane such as the dithiothreitol and progesterone induced hyperpolarization and depolarization of the membrane 16% and 40%, respectively. The presence of propranolol and L-alpha-lysophosphatidylcholine, which affect the ionic gradients present across the plasma membrane, both induced a depolarization from 43% and 92% respectively. Finally, the addition of tetraphenylboron (TPB-) on the incubation medium, enhanced the value of the psi 75%. These studies are transcendent because with the utilization of agents depolarizing, or hyperpolarizing we obtain changes in the psi from -80 +/- 0.6 mV, until -6 +/- 0.6 mV changes of 74 +/- 1.5 mV across of the sperm cell membrane.

Cell Membrane↗
PubMed1991

[Profile of the membrane potential of mammalian sperm during maturation, ejaculation and capacitation].

The accumulation of lipophilic cation radiolabeled tri-phenylmethyl phosphonium (TPMP+) was utilized to determine the resting membrane potential across the plasma membrane psi. Washed sperm of mammalian was suspended and incubated in low-K+ and high-K+ medium and allowed to take up the cation to a steady-state (20 min at 37 degrees C). By using this differential, the value obtained was transformed at value concentration using the intracellular volume and with these values inserted in the Nernst equation, we obtained the psi. During the maturation process the psi obtained in sperm cells of caput of the epididymis of New Zealand white rabbits was -75(+/-)-3 mV, in sperm cells of corpus and cauda, the psi obtained were -60(+/-)-5 and -52 +/- 3.5 mV, respectively. In the ejaculated spermatozoa the psi obtained was -69 +/- 2 mV. Finally, during the capacitation of human spermatozoa induced by the addition of calcium ions and the ionophore A23187 the psi obtained was -35 +/- 4 mV. These changes in the psi are significant because when the mammalian sperm cells are under different physiological conditions the membrane polarity is modified for the hyperpolarization and depolarization observed.

Animals↗
PubMed1991

[Sialyltransferase activity in the spermatic membrane and its relation to human fertility and sterility].

Sialyltransferase activity was determined on normospermic men sperm cells (greater than 80 x 10(6) sperm/ml and 75% motility) and oligospermic infertile sperm cells (less than 20 x 10(6) sperm/ml and less than 20% motility) and asthenospermic (greater than 40 x 10(6) sperm/ml and less than 10% motility). Sialytransferase activity is quantified by means of the transference of radioactivity of CMP-3H-sialic acid toward the exogenous acceptor (asialofetuin). The enzyme substrate complexes formed in presence of phosphotungstic acid result precipitated insoluble, which was retained on glass fiber filter. The sialyltransferase activity decrease in oligospermic sperm cells 62 +/- 3% and in the asthenospermic decreased 57 +/- 4% with respect normospermic sperm cells. The decrement on sialyltransferase activity in the infertile sperm, permits to assume that this enzyme probably participates as a direct cause of its pathology with detrimental structural and functional integrity of the plasma membrane.

Cell Membrane↗
PubMed1989

[Role of sialyltransferase and neuraminidase in the epididymis of rats].

The sialylation and desialylation in the rat epididiymis is the transference or remotion of sialic acid, to or from an adequate acceptor (glyco or sialogycoprotein). The sialylation of the glycoprotein or glycolipids is determinated by sialyltransferase activity; the homogenates from caput region showed 14 times more sialyltransferase activity than homogenates from cauda epididymis. The desialylation of the sialoglycoproteins is quantified by neuraminidase activity, and it can be observed that the homogenate from the caput zone shows 3 times more activity than homogenates from cauda epididymis. When relatione the activities of sialytransferase/neuraminidase of the caput zone and the cauda zone, the obtained values were 0.19 +/- 0.03 and 0.04 +/- 0.005, respectively. The relation between the activities of neuraminidase/sialiltransferase of the caput and the cauda zone showed the following valves: 5 +/- 0.6 and 25 +/- 3.3, respectively. The results have shown that sialylation is more active in the caput than in the cauda. Besides, while valvating the desialylation we observe that it is more effective in the cauda epididymis.

Animals↗
PubMed1989

[Type-I and -II estradiol binding sites in the endometrium during blastocyst implantation].

The properties of type I and occupied and unoccupied type II cytosolic estrogen binding sites in the rat endometrium were analyzed on day five of pregnancy; the samples studied correspond to blastocyst receptive endometrium (implantation sites), nonreceptive endometrium and ovariectomized uterine horn endometrium, from the same pregnancy rats. The occupied binding site type II was analyzed by exchange assays. Dissociation constant obtained from experiments carried out at 4 or 25 degrees C are similar for each one of the binding site at the three different endometrium samples; the binding capacity (femtomoles/mg protein) from the sites type I and type II and the ratio between occupied (by endogenous estradiol) and unoccupied site type II, seems to be characteristic for each one of the three analyzed endometrium.

Animals↗
PubMed1988

Effect of steroid hormones and capacitation on membrane potential of human spermatozoa.

The accumulation of the lipophilic cation radiolabeled triphenylmethylphosphonium (TPMP+) was utilized to determine the resting membrane potential across the plasma membrane (psi) on human sperm. Washed sperm were suspended and incubated in low-K+ and high-K+ medium and allowed to take up the cation to a steady state (that is, 20 min at 37 degrees C). The data were transformed according to concentration using the intracellular volume and with these values inserted in the Nernst equation we obtain psi. When the concentration of K+ was low in the medium, the psi was -69 +/- 2 mV, the psi was temperature- and pH-dependent. The sperm were incubated in the same conditions in the presence of testosterone, estradiol, and progesterone. The addition of these hormones induced the decrease in psi by about 29%, 32%, and 40%, respectively. On the other hand, capacitation of spermatozoa was induced by the addition of calcium and the ionophore A23187 and in these conditions the psi decreased 50%. The action of the hormones on sperm membrane was accompanied by some steroid-dependent structural modification promoting the psi decrease. This effect plays an important role in the capacitation, preparing it for sperm penetration in the ova.

Gonadal Steroid Hormones↗