Biomedical subjects

A Zárate

Publications and source records attributed to A Zárate.

At least 19 recordsLinked to original sources

PubMed2001

Hormone replacement therapy increases ACTH/dehydroepiandrosterone sulfate in menopause.

OBJECTIVE: To demonstrate that hypoestrogenism in menopause is in part responsible for the decrease in circulating dehydroepiandrosterone sulfate (DHEA-S) and ACTH levels. To test this hypothesis, 25 postmenopausal women aged 47-60 years, were given orally conjugated equine estrogen (CEE) to study the effect on circulating DHEA-S, cortisol and ACTH. DESIGN: A prospective, non-blinded study was performed. Hormonal levels were analyzed before and after three cycles of CEE 0.625 mg/day for 21 days followed each by chlormadinone acetate for 5 days. RESULTS: Low baseline levels of DHEA-S increased significantly after HRT (1.71+/-0.75 to 3.3+/-1.5 micromol/l, (P<0.001). ACTH levels augmented moderately from 3.26+/-1.4 to 4.7+/-1.8 pmol/l (P<0.05) and cortisol from 350.4+/-118 to 450.8+/-144 nmol/l (P<0.01). A positive correlation was obtained between 17 beta-estradiol and ACTH (r=0.48), estradiol and cortisol (r=0.52) as well as estradiol and DHEA-S (r=0.60). In addition, the correlation was highly significant (P<0.001) between ACTH and DHEA-S at the term of HRT. CONCLUSION: HRT increased DHEA-S, ACTH and cortisol concentrations, which may suggest that this therapy may exert a stimulatory effect on the pituitary gland when baseline hypoestrogenism is present, but further studies are required to clarify the mechanism underlying this process.

Adrenocorticotropic Hormone↗

PubMed2000

[Effectiveness of acarbose in the control of glucose tolerance worsening in pregnancy].

Gestational diabetes is considered as a carbohydrate intolerance, first diagnosed during pregnancy. A previous stage of carbohydrate impairement may precede its abnormality; therefore it may be convenient to establish some management in order to avoid the gestational diabetes. Six pregnant women who had moderate elevated level of blood glucose at fasting and postprandial were treated with acarbose, alpha-glucosidase inhibitor agent, given three times a day before meals. In all patients fasting and postprandial glucose levels were normalized; pregnancies went uneventful and the newborns were considered normal. Acarbose was associated with intestinal discomfort which persisted during the whole pregnancy.

Acarbose↗

PubMed2000

[Circulating leptin doesn not change in postmenopausal women receiving replacement therapy with tibolone].

After informed consent, blood samples were obtained to measure leptin, FSH, LH, insulin, 17-beta-estradiol, and IGF-1. No differences in serum leptin was observed between the women on Tibolone (8.1 +/- 4.2 ng/mL) and the control group (7.4 +/- 3.7 ng/mL). Women on Tibolone had lower insulin levels (16.4 +/- 1.8) than women without therapy (19.4 +/- 1.3 mU/mL) (p < 0.05). On the contrary IGF-I levels were elevated (150.0 +/- 16.4) as compared with those in non-treated women (121.0 +/- 13.4 ng/mL) (p < 0.05). Body weight was similar between the two groups. From these data it is concluded that Tibolone, as replacement therapy, does not increase circulating leptin and seems to have no effect on body weight.

Aged↗

PubMed1999

Upper body obesity and hyperinsulinemia are associated with anovulation.

The objective of this study was to determine the effect of body fat distribution and hyperinsulinemia on the occurrence of ovulation. Fifty-six women (20-35 years old) either with overweight or obesity (body mass index >/=25) were studied. They were classified in two groups according to waist/hip ratio (WHR); one with predominance of adiposity in the upper body segment (n = 29, WHR >0.85) and the other with predominant adiposity in the lower body segment (n = 27, WHR </=0.85). Basal body temperature and serum progesterone were determined in each cycle during 6 months. Serum insulin levels were measured at baseline and 30, 60, 90, 120 and 180 min after a 75-gram oral glucose load. The mean insulin values in response to oral glucose load in patients with upper body segment obesity were significantly higher than those corresponding to women with lower body segment obesity. Furthermore, the ratio between ovulated cycles and all the cycles studied in patients with upper body segment obesity was significantly lower than that observed in patients with lower body segment obesity. Upper body obesity seems to affect the ovulatory process and this may be related to the presence of hyperinsulinemia.

Adipose Tissue↗

PubMed1999

Increased serum levels of growth hormone and insulin-like growth factor-I associated with simultaneous decrease of circulating insulin in postmenopausal women receiving hormone replacement therapy.

OBJECTIVE: Decreases in circulating growth hormone (GH) and its main biological messenger insulin-like growth factor-I (IGF-I) have been interpreted as part of the aging process. Because estrogens participate in modulating GH synthesis and secretion, hypoestrogenism in menopausal women may lead to GH deficiency. The aim of the present study was to determine the effect of hormone replacement therapy (HRT) on both GH and IGF-I levels as well as insulin concentrations in 50 menopausal women. DESIGN: Patients were assigned randomly into two treatment groups of 25 each; one group received three cycles of conjugated equine estrogen (CEE) 0.625 mg/day for 21 days, and the other, 1.25 mg/day during 21 days. Each also received chlormadinone acetate for 5 days. There was a control group consisting of regularly menstruating women. RESULTS: In the menopausal women, HRT increased significantly (p < 0.001) the low levels of GH and IGF-I; on the contrary the baseline insulin levels declined (p < 0.001) with HRT. A significant linear correlation (r = 0.90) was found between GH and IGF-I as well as with estradiol levels (r = 0.74) in the group of menopausal women receiving CEE 0.625 mg/day. This group of patients had a significant correlation (r = -0.63) between insulin and estradiol levels. No correlation was observed in the group receiving CEE 1.25 mg/day. CONCLUSIONS: HRT restored GH, IGF-I, and insulin levels to normal values in all women. Further research needs to be done to establish the beneficial effect of HRT regarding the prevention of the metabolic effects presumably caused by derangement in the somatotropic axis associated with aging.

Aged↗

PubMed1997

Evaluation of an immunoenzymometric assay (IEMA) using automated system for determination of luteinizing hormone and follicle stimulating hormone.

It has been proposed that automated systems for immunoenzymometric assay (IEMA) may substitute traditional radioimmunoassay (RIA) for measurement of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in blood due to the advantage of being more rapid, higher sensitivity, lower cost and not requiring radioactive reagents. The study was designed to evaluate both systems using serum samples to determine luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations. The automatic system (ES-300) for IEMA utilized two monoclonal antibodies, one of them on the solid phase was the specific extractant for the antigen, and the other was a peroxidase labeled antibody which recognizes a different epitope in the antigen molecule, specifically bound in linear proportion to the antigen concentration. Blood samples were obtained from patients who were treated at the hospital for various clinical problems ("problem group") as well as blood samples from patients in whom FSH and LH concentrations were already known ("high", "medium" and "low" levels) by previous RIA ("control group"). IEMA showed a higher sensitivity, 0.42 and 0.96 mIU/ml for FSH and LH, respectively, whereas RIA was 1.95 mIU/ml for both hormones. Intra- and interassay coefficient of variation were below 10% within the range of 15-150 mIU/ml for FSH and 5-100 mIU/ml for LH; however, the coefficient of variation was 15-25% at lower concentrations of FSH and LH. Accuracy of IEMA was evaluated by recovery percentage, thus when high and medium concentrations of FSH and LH were analyzed the recovery was between 99-104%. On the other hand, the recovery was 110% when low levels of FSH and LH were used. In conclusion, IEMA resulted reliable when FSH and LH concentrations are in the middle and high range; likewise, the detection limit of IEMA was lower than RIA, particularly for FSH. On the bases of these results, IEMA showed several advantages over RIA, but its reliability diminishes when serum samples contain low FSH and LH concentrations. It is important to extend these studies to steroid assays and elaborate a database in each laboratory.

Adult↗

PubMed1997

[Postmenopausal metabolic effects of a synthetic estrogen (tibolone) with a characteristic estrogenic action].

Life expectancy in women has nearly reached 80 yr old, therefore the postmenopausal period is considered very important, particularly regarding the benefits of hormone replacement therapy. At the present there are several therapeutic options in order to protect against the long term complications resulting from chronic hypoestrogenism and avoiding some of the side effects associated with estrogens medication, tibolone is a synthetic steroid possessing mild estrogenic effect and some progestagenic and androgenic actions; moreover this steroid does not require to be converted to estradiol. We studied the effect of administering tibolone 2.5 mg daily orally during six months to 11 postmenopausal women in order to analyze any changes on several biochemical markers. Estradiol concentrations were not modified although FSH, total cholesterol, low density lipoproteins and triglycerides levels decreased. Collaterally there was observed an increment in high density lipoproteins and sexual hormone binding globulin. It is concluded that tibolone exerts its effect directly on specific receptor tissues without being converted to estradiol so that this finding may help to understand some of the clinical effects, particularly upon mammary gland, endometrium and body weight.

Aged↗

PubMed1997

[The proportion of molecular forms of gonadotropins changes in patients with polycystic ovaries].

It is known that protein hormones circulate as different molecular forms and the relative proportion of these isoforms changes according to endocrine milieu. In particular gonadotropins, both LH and FSH, isoforms suffer variations related to the estrogen levels; thus sera obstained from menopausal women show a predominance of larger molecular forms which are considered as having lesser biological activity and the administration of estrogen replacement therapy is followed by the appearance of intermediate molecular forms possessing higher biological activity. This chormatographic pattern with predominance of intermediate isoforms is typical at midcycle in sera from normal women at the periovulatory stage. Present study showed that sera obtained from anovulatory women, such as patients with polycystic ovaries a predominance of larger and smaller molecular weight isoforms, exhibiting a chromatographic pattern different from that observed in normal women. It is speculate that there is some imbalance between the ovarian steroid synthesis and gonadotropin production in the stage of tertiary structural conformation.

Adult↗

PubMed1997

[Use of metformin in the management of adolescents with polycystic ovary syndrome].

Present study was designed to test that insulin resistance due to hyperinsulinism contribute to the clinical features of polycystic ovarian syndrome (POS). We studied 15 women wit POS who received Metformin 400 mg b.i.d during six months; blood levels of estradiol, testosterone (T), sexual hormone binding globulin (SHBG), insulin like growth factor-I (IGF-I) were determined. In response to treatment women exhibited decrement in serum levels of T as well as an increment, no significative, in both SHBG and IGF-I. Most of the patients showed reduction in body mass index and presented restoration of menstrual cycles. It is concluded that Metformin treatment exerts some metabolic effect which in turn induces some clinical improvement.

Adolescent↗

PubMed1996

Gastrin levels in mothers and neonates at delivery in various perinatal conditions.

BACKGROUND: This study was designed to assess the variations of gastrin (Ga) serum levels in mothers and newborns at birth in some perinatal disorders. MATERIALS AND METHODS: Ga levels were measured by RIA in maternal serum, amniotic fluid and cord sera of newborns in 55 cases with the following conditions: normal pregnancy and eutocic vaginal delivery (n = 8), repeat cesarean section (n = 10), and cardiotogographic register suggestive of fetal compromise (n = 15), cephalopelvic disproportion (n = 8), preeclampsia (n = 7) and postdate pregnancy (n = 7). Statistical analysis was performed by Mann-Whitney U test. RESULTS: Ga levels in cord sera of newborn and amniotic fluid in normal pregnancy and eutocic delivery were significantly higher (p < 0.02 and p < 0.01, respectively) than those found in patients with repeat cesarean operation. Serum Ga concentrations in women with postterm pregnancy were significantly higher (p < 0.02) than in women with prior cesarean section. Ga levels in amniotic fluid samples in the presence of suspected fetal compromise and postdate pregnancy were significantly higher (p < 0.001) than those observed in women who had repeat cesarean operation. CONCLUSION: Vaginal delivery and perinatal pathology may induce hypergastrinemia in both mother and neonate at birth.

Adult↗

PubMed1996

[Changes in molecular forms of sex hormone binding globulin during menstrual cycle and menopause].

Sex hormone binding globulin (SHBG) is a glycoprotein that transports mainly androgens and estrogens regulating the amount of free and bound hormone which in turn plays a role in the metabolic balance. It is also known that estrogens increase the hepatic production of SHBG which circulates in various molecular forms containing different amounts of sialic acid as the main component of carbohydrates. In the present work we studied physiological variations of molecular forms of SHBG during the normal menstrual cycle and the menopause. During the follicular phase the form 54 KD was the predominant variant, in the periovulatory period was isomers 90 KD, and during the luteal phase corresponded to both 54 and 90 KD. In the menopause dimeric form of 90 KD corresponded to the major proportion and was present a higher molecular forms of 115-135 KD. Following estrogen therapy the chromatographic profile changed as to that observed during the menstrual cycle. Important changes in the proportion of sialic acid were observed in each of the phases of menstrual cycle and following estrogen replacement. And increase in the amount of sialic acid corresponded to higher estrogen concentrations. It is concluded that SHBG concentrations varies during the menstrual cycle according the estrogen levels which in addition regulates the proportion of molecular forms and sialic acid containt.

Adult↗

PubMed1995

Elevation of activity of creatine phosphokinase (CK) and its isoenzymes in the newborn is associated with fetal asphyxia and risk at birth.

OBJECTIVE: To investigate the relationship of creatine phosphokinase and its isoenzymes with fetal asphyxia and risk at birth. METHODS: Thirty-five pregnant women with high-risk pregnancy were studied. RESULTS: In 21 patients, fetal distress was diagnosed by interpretation of the fetal heart rate tracing (FHR). The remaining 14 women, having normal fetal cardiotocography, were considered as the control group. Total CK and its isoenzymes activity was measured in cord sera and 24 h after birth in peripheral blood. Abnormal FHR patterns correlate well with elevated enzyme activities. Total CK and its isoenzymes (CK-MM, CK-MB, and CK-BB) exhibited higher values in asphyxiated infants as compared to normal neonates. Electrocardiographic ischemia occurred in seven newborns who had elevated CK-MB and CK-BB levels, both at birth and within 24 h postpartum. Chromatographic study showed in normal neonates that the predominant isoenzyme was CK-MM, whereas CK-BB activity was negligible. In the newborns with abnormal FHR, CK-MB and CK-BB were increased with predominance of CK-MB. CONCLUSIONS: Antepartum fetal distress is associated with release of CK-BB, and particularly CK-MB; therefore, these biochemical markers may indicate either brain or myocardial damage.

Asphyxia Neonatorum↗

PubMed1995

Patients with TSH-secreting pituitary tumor possess different TSH molecular isoforms.

The objective of the study was to demonstrate if TSH secreted by a pituitary tumor correlates with particular molecular forms of TSH. Aliquots of sera from two hyperthyroid patients with TSH-secreting pituitary tumor were subjected to gel filtration chromatography to be assayed for TSH. The assay was repeated in one case after transsphenoidal adenomectomy. Sera from two additional patients with long-lasting primary hypothyroidism, and from two subjects with normal thyroid function were also chromatographed. Molecular weight (mol wt) of isoforms was calculated on a calibration curve obtained with molecular markers. The molecular variants were characterized on the basis of elution volume, mol wt, and partition coefficient. Chromatographic profile of the two cases with TSH-secreting pituitary tumor exhibited mainly two peaks of TSH immunoreactivity. The major component of immunoreactivity eluted as a peak corresponding with the alpha-subunit of the glycoprotein. This pattern was different from that obtained in sera from two women with hypothyroidism, which was heterogeneous and presented a predominance of molecular variants corresponding with mol wt of 22 and 29 kD, and no alpha-subunit was present. In cases of normal thyroid function the chromatographic profile showed that the major proportion of TSH eluted simultaneously with the labeled standard and 22 kD marker. These results demonstrate that TSH secreted by pituitary tumors is composed of various molecular forms and the alpha-subunit is the major component. This chromatographic profile is different from that observed in other cases with elevated concentrations of TSH as it occurs in primary hypothyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

The magnitude of growth hormone elevation is related with the proportion of monomeric form in acromegaly.

In acromegalic patients monomeric GH form constitutes the larger proportion of circulating GH; however, no data are available concerning the relation between total GH elevation and the predominance of GH forms. Therefore, we studied the relationship between the degree of GH elevation and the proportion of GH isoforms. Sera from 11 patients with active acromegaly were subjected to gel chromatography on Sephadex G-100 column and fractions were collected for RIA to measure GH. The monomeric form of GH was predominant and exhibited a lineal correlation (r = 0.76, p < 0.01) with the circulating GH, thus the higher elevation of GH, the major proportion of monomeric GH. IGF-1 changes correlate with changes in monomeric GH but no better than for total GH. There was a correlation observed (r = 0.65) between the proportion of low GH forms and the presence of hyperglycemia, although the physiological role of the lower molecular GH forms is still unknown. In conclusion, it was demonstrated that the relative proportion of GH molecular forms changes according to the magnitude of the elevation of total GH.

Acromegaly↗

PubMed1994

Heterogeneity of late-onset adrenal 3 beta-ol-hydroxysteroid dehydrogenase deficiency in patients with hirsutism and polycystic ovaries.

Nine women with clinical features of polycystic ovarian syndrome (PCOS) were studied in order to establish the differential diagnosis with late-onset adrenal hyperplasia (LOAH). Their hirsutism was classified as moderate in five patients and severe in the remaining four cases. All patients had bilateral polycystic ovarian enlargement by ultrasound examination. As a control group five women with normal ovarian function without hirsutism were submitted to the same protocol of study. The patients studied as well as the women of the control group had basal serum determinations of pregnenolone (P5),17-hydroxypregnenolone (17-OHP5),dehydroepiandrosterone (DHEA), pregesterone (P), 17-hydroxyprogesterone (17-OHP), androstenedione (A), testosterone and cortisol by radioimmunoassay techniques. The basal serum levels of androgens showed no correlation with the severity of hirsutism or with the ultrasound findings. An adrenal stimulation with synthetic adrenocorticotropic hormone (ACTH) to all women was performed in order to assess their adrenal responsiveness. The analysis of the ratios between delta 5 and delta 4 steroids demonstrated a partial enzymatic blockade at the level of 3 beta-o1-hydroxysteroid dehydrogenase (3-HSD) in three patients. The blockade was particularly in the conversion of P5 to P and 17-OHP5 to 17-OHP. The lack of delta 4 steroid secretion in the presence of normal increase of delta 5 precursors following ACTH was noted. These findings confirm the clinical use of the ACTH stimulation test to reveal the presence of enzymatic alterations in adrenal steroidogenesis in some patients previously considered to have PCOS. Since it wa demonstrated that the conversion steps were affected in variable degrees, the presence of different isoenzymes of 3-HD is suggested.

3-Hydroxysteroid Dehydrogenases↗

PubMed1994

Changes in the prolactin serum isoforms secreted by a pituitary adenoma associated with therapy.

Variations in serum molecular forms of prolactin (PRL) from an adolescent woman presenting amenorrhea-galactorrhea are reported. Persistent hyperprolactinemia and hypoestrogenism were demonstrated as well as the presence of a pituitary tumor with suprasellar extension. Bromocriptine was given at progressive doses up to 37 mg daily, decreasing the hyperprolactinemia and galactorrhea. After 2 years of treatment the patient noticed symptoms of gastric intolerance, bromocriptine was discontinued and a rebound of hyperprolactinemia was observed. Lisuride was administered instead resulting in a new decrease in PRL serum levels, disappearance of galactorrhea and beginning of regular menses. Serum gel chromatographic analysis was carried out before and during lisuride treatment. The first chromatographic analysis showed a predominance of high molecular weight (approximately 66 KD) PRL, accounting for more than 90% of the immunoreactive PRL. The second chromatography showed the major peak of immunoreactive PRL displaced to the right (molecular weight of 22 KD), which was eluted near the PRL standard. With these chromatographic patterns it is concluded that the pituitary macroprolactinoma secreted different molecular forms of PRL and treatment with lisuride appeared to exert some effect on the PRL molecular size secreted by the pituitary.

Adolescent↗

PubMed1993

Distribution of growth hormone isoforms in sera from women with normal ovarian function, galactorrhea, and normoprolactinemia.

OBJECTIVE: To demonstrate if GH concentrations and molecular heterogeneity of GH correlates with the presence of galactorrhea in normoprolactinemic women with normal ovarian function. DESIGN: Aliquots of sera from women with normal ovarian function and normoprolactinemic galactorrhea were subjected to gel filtration chromatography, and the fractions were assayed for GH by the use of radioimmunoassay. Molecular weight of isoforms was calculated on a calibration curve obtained with molecular markers. The molecular variants were characterized on the basis of elution volume, molecular weight (MW), and partition coefficient. RESULTS: Basal serum GH levels were moderately elevated in all six normoprolactinemic women exhibiting galactorrhea. Chromatographic study of sera from these normoprolactinemic women showed the predominance of 40 to 50 kd molecular forms of GH as well as some very low MW GH isoforms. This pattern was different from that obtained in sera from normal women without galactorrhea who presented a predominance of heavier (> 60 kd) isoforms eluted before the GH labeled standard. The monomeric forms were present in less proportion but there was no significant difference as compared with galactorrheic group. CONCLUSIONS: Our investigation demonstrated elevated GH basal serum levels is normoprolactinemic women with galactorrhea, and chromatography in gel showed a low proportion of the large MW GH variants associated with a higher proportion of the dimeric forms and very low MW forms of GH. This is different from normal women without galactorrhea who had a predominance of heavier MW GH variants and lesser proportion of < 16 kd isoforms. It is concluded that an increased GH secretion may be responsible for abnormal lactation despite normal PRL levels in some women with normal ovarian function.

Adult↗

PubMed1993

Determination of the steroidogenic capacity in premature ovarian failure.

OBJECTIVE: To determine the secretion of precursors, intermediate and final products of androgen biosynthesis in women with premature ovarian failure (POF). PATIENTS: Seven patients 20 to 34 years of age with idiopathic POF and a control group of six women 27 to 29 years of age with normal ovarian function studied during the early follicular phase were included. DESIGN, INTERVENTIONS: In all patients an adrenal stimulation test was performed as follows: a short dexamethasone (DEX) inhibition was carried out the night before the corticotropin (ACTH, 0.25 mg, Cortrosyn; Organon, Orangeburg, NY) stimulation test, obtaining blood samples in basal conditions, post-DEX inhibition as well as at 60, 120, and 180 minutes after the ACTH bolus. MAIN OUTCOME MEASURES: Using specific RIA serum concentrations of delta 5 precursors (pregnenolone, 17-hydroxypregnenolone, DHEA), delta 4 intermediates (P, 17-hydroxyprogesterone, androstenedione) and the final products T and cortisol (F) were measured. RESULTS: Adrenal inhibition and stimulation responses in both groups of patients showed no differences for delta 5 precursors and F. On the other hand, delta 4 intermediates and androgens exhibited significant differences at the level of response to ACTH stimulation. Patients with POF had significantly lower values than those of control group. CONCLUSION: An important decrement in the steroidogenesis was noticed in POF, particularly in androgen synthesis, revealing the selective participation of the adrenal gland in steroid production.

Adrenocorticotropic Hormone↗