Biomedical subjects

R Ochoa

Publications and source records attributed to R Ochoa.

At least 19 recordsLinked to original sources

PubMed2001

Insulin-like growth factor I, epidermal growth factor and transforming growth factor beta expression and their association with intrauterine fetal growth retardation, such as development during human pregnancy.

AIM: Fetal intrauterine growth retardation (IUGR) is one of the most common obstetric problems, with a frequency of 12% in Mexico. In the past, investigations have focused on extrinsic causes of IUGR. More recent studies have examined the intrinsic factors that cause fetal intrauterine growth. Maintenance of fetal growth has been attributed to insulin-like growth factor (IGF), epidermal growth factor (EGF) and transforming growth factor beta (TGF-beta). The objective of this study was to assess the levels of these growth factors during pregnancy and to determine whether or not low concentrations are associated with IUGR. METHODS: Nine women whose pregnancies were complicated by IUGR and a group of nine women whose pregnancies exhibited normal fetal intrauterine growth were studied. IUGR was determined by sonography and confirmed by weight at birth. Venous blood samples were taken from both groups of pregnant women at the end of each trimester. Enzyme-linked immunosorbent assays, immunoradiometric assays and radioimmunoassays were used to process samples, and the results were analysed by anova. RESULTS: IGF-I levels increased in both groups during pregnancy, but the increase was lower (p < 0.001) in the IUGR group throughout pregnancy and at delivery. EGF did not show any significant changes during pregnancy. Blood TGF-beta levels varied only during the first trimester of pregnancy. The differences were not statistically significant. However, TGF-beta concentrations were higher in the pregnancies with IUGR. Women in the IUGR group were smaller than in the control group (p < 0.05), and, using the covariance test (p < 0.05), this was found to be correlated with IGF-I levels but not with EGF or TGF-beta levels. CONCLUSIONS: Changes in fetal weight might be explained by the different concentrations of IGF. The structural homology between IGF-1 and insulin could mean that the presence of higher levels of IGF would result in a increased energetic metabolism that could contribute to fetal growth. EGF levels were not related to IUGR, and TGF-beta levels increased only during the first 3 months in the IUGR group. This observation correlates with the in vitro action of TGF-beta as a negative factor of growth, but as a positive support for sustaining early pregnancy. Our data illustrates that low height represents an increased risk factor for IUGR. These data also correlate with the studies involving extrinsic factors.

Adult↗

PubMed2001

P53+/- hemizygous knockout mouse: overview of available data.

The performance of the p53-/- transgenic (knockout) mouse model was evaluated through review of the data from 31 short-term carcinogenicity studies with 21 compounds tested as part of the International Life Sciences Institute's (ILSI) Alternatives to Carcinogenicity Testing (ACT) project, together with data from other studies which used comparable protocols. As expected based on the hypothesis for the model, a significant number (12/16 or 75%) of the genotoxic human and/or rodent carcinogens tested were positive and the positive control, p-cresidine, gave reproducible responses across laboratories (18/19 studies positive in bladder). An immunosuppressive human carcinogen, cyclosporin A, was positive for lymphomas but produced a similar response in wild type mice. Two hormones that are human tumorigens, diethylstilbestrol and 17beta-estradiol, gave positive and equivocal results, respectively, in the pituitary with p53-deficient mice showing a greater incidence of proliferative lesions than wild type. None of the 22 nongenotoxic rodent carcinogens that have been tested produced a positive response but 2 compounds in this category, chloroform and diethylhexylphthalate, were judged equivocal based on effects in liver and kidney respectively. Four genotoxic noncarcinogens and 6 nongenotoxic, noncarcinogens were also negative. In total (excluding compounds with equivocal results), 42 of 48 compounds or 88% gave results that were concordant with expectations. The technical lessons learned from the ILSI ACT-sponsored testing in the p53+/- model are discussed.

Animal Testing Alternatives↗

PubMed2001

Serum leptin and somatotropin components correlate with neonatal birth weight.

OBJECTIVE: To determine whether cord sera leptin and components of the somatotropin axis - growth hormone (GH), total (t) and free (f) insulin-like growth factor (IGF), IGF-binding protein-3 (IGFBP-3), and insulin - correlate with birth weight. DESIGN: Cross-sectional study of 22 newborns, 12 with normal birth weight (NBW) and 10 with low birth weight (LBW), in a population of healthy mothers with an apparent normal pregnancy. METHODS: Paired mother-neonate blood samples were obtained at vaginal delivery in order to measure leptin and the somatotropin axis components. RESULTS: In all cases maternal blood concentrations of leptin, t and fIGF-I, its carrier protein IGFBP-3, and insulin were higher than in the cord sera of the newborns, regardless of their birth weight. On the contrary, maternal GH levels were lower than in their neonates. LBW neonates had decreased levels of leptin, tIGF-I, and IGFBP-3 as compared with those levels in NBW offspring; however, GH concentrations were higher in LBW neonates. Birth weight showed a significant correlation with cord sera leptin, tIGF-I, IGFBP-3, and GH; nevertheless birth weight was neither interrelated with fIGF-I nor with insulin levels. CONCLUSION: These data demonstrate that birth weight is significantly correlated with both leptin and some components of the somatotropin axis; on the other hand, no correlation was observed between leptin concentrations and each one of the components of the somatotropin axis. It is suggested that fetal leptin and the somatotropin axis cooperate in intrauterine growth and birth weight.

Adult↗

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

Differential effects of octreotide treatment and transsphenoidal surgery on growth hormone-binding protein levels in patients with acromegaly.

OBJECT: The high-affinity growth hormone-binding protein (GHBP) represents the extracellular portion of the growth hormone (GH) receptor, and its serum levels are a reflection of the tissue receptor status. Levels of GHBP are decreased in patients with active acromegaly, probably because of downregulation of GH receptors. However, there are no studies of patients with acromegaly in which the effects of medical (that is, administration of somatostatin analogs) and surgical therapy on GHBP levels have been compared. That is the task the authors set out to accomplish in this study. METHODS: The authors studied seven patients in whom acromegaly had been recently diagnosed. They examined these patients at baseline, 2 months after octreotide treatment (subcutaneous administration of 100 microg octreotide three times per day), and 1 month after transsphenoidal surgery. Growth hormone-binding activity was measured, as well as the following biochemical markers of the somatotropic axis: GH suppression induced by oral administration of glucose, insulin-like growth factor-I (IGF-I), and insulin-like growth factor-binding protein-3 (IGFBP3). Although octreotide treatment induced a decrease in the levels of GH, IGF-I, and IGFBP3, as well as an increase in the level of GHBP, these biochemical markers did not reach normal levels. On the other hand, after transsphenoidal surgery, GHBP levels became normal, particularly in those patients in whom serum GH could be suppressed to an undetectable level after glucose loading. CONCLUSIONS: The authors conclude that persistently low GHBP levels in patients with acromegaly are normalized by successful pituitary surgery and correlate well with disease activity.

Acromegaly↗

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↗

PubMed1998

Cohort size and maximum likelihood estimation of mortality parameters.

The purpose of this study was to investigate the effects of cohort size on maximum likelihood estimates of mortality parameters. Recent experimental investigations have stressed the importance of large cohorts for detecting leveling off of mortality rates at older ages. In the present study, emphasis was placed on evaluation of relatively small cohorts (about 150-300 individuals). Deaths were simulated under the assumption of the frailty mortality model. Two different parameter sets that resulted in differences in mean life span of more than twofold were used for simulations. Our smallest cohorts yielded parameter estimates that had generally good statistical properties, but relatively large standard errors. For tests of hypotheses concerning equality of parameters among populations or experimental treatments, empirical standard errors (obtained from several cohorts) were preferable to asymptotic standard errors (obtained for single cohorts). In particular, empirical standard errors yielded reliable type I error rates.

Cohort Studies↗

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 transcendence of prolactin and its relation to the immune response].

Prolactin is a hormone involved in a variety of physiological processes in male and female of several vertebrates species. In mammalian included the human, it has been suggested that prolactin plays a role in immunoregulatory mechanism. There are some evidence in the sense that exists a notable bidirectional interaction between prolactin and the immune systems. This finding has stimulated the research on this area. Prolactin has stimulative effects on the lymphocytes and on the immune responses, and the cytokines production changes the prolactin concentration, so modifying its biological action. These reciprocal effects involve the presence of specific receptors. The prolactin receptors have been demonstrated on lymphocytes and other accessory cells. This review tries to summarize the interaction between immune and neuroendocrine systems and the importance of neuroimmune endocrinologic study.

Female↗

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

[Clinical trial with tibolone in postmenopausal replacement therapy].

Estrogen deficiency is the basic change in women around the climateric stage. This hormone deficiency is different among women regarding the age and intensity of symptoms. The hormone replacement has proved its benefit on relieve of symptoms and long term effect on prevention of cardiovascular disease and osteoporosis. A new pharmacological agent Tibolona has been studied recently as replacement therapy. This work reports the results obtained with the use of Tibolona in 36 postmenopausal women. The effectiveness and security were confirmed as well as the low occurrence of side effects. It was also apparent that this therapy had a relevant effect on the psycho-emotional component and upon the improvement of sexual satisfaction and activity.

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↗

PubMed1996

[Validation of a ultramicroELISA for detecting antibodies against hepatitis B surface antigen].

The results of a validation study of the ultramicroanalitical assay for the detection of antibodies against the hepatitis B surface antigen (UMELISA anti-HBsAg), which was carried out by comparing the results obtained with the Hepanostika anti-HBsAg, commercial diagnosis kit are presented. For this purpose, sera from the clinical assays of the Cuban recombinant vaccine against hepatitis B were used. With the first sera group (n = 30) it was obtained, 93.1% of sensitivity, 98.5% of specificity and a concordance of 94.3%. The correlation coefficient showed a similar trend of the results (p < 0.01) and no significant differences were found in the average geometrical titre (TPG) between both assays (p > 0.05). With the second group (n = 100), whose assays were carried out at the "Pedro Kouri" Institute of Tropical Medicine (PKI) and at the Immunoassay Center (IAC) simultaneously, it was observed a sensitivity of 96.25% in both centers, a specificity of 75% at the PKI and of 90% at the IAC, and a coincidence of 92% and 95%, respectively. The correlation coefficient presented similar values and there were no significant differences between the TPG obtained by the two methods (p > 0.05). The results attained show in general the validity of the new assay and the feasibility to put it into practice either for following up the infection, or for carrying out clinical assays of vaccine evaluations.

Enzyme-Linked Immunosorbent Assay↗

PubMed1995

Tirilazad mesylate--effects of the 21-aminosteroid on the lymphoid system of laboratory animals: a comparison with the glucocorticoid methylprednisolone.

Four-week toxicity studies with the 21-aminosteroid tirilazad mesylate were conducted in Sprague-Dawley rats, beagle dogs, and cynomolgus monkeys to support development of the drug for use in various clinical syndromes of injury to the central nervous system of humans. As the immune system is involved in many of the obvious side effects of glucocorticoids used currently for this indication, particular attention was directed to the lymphoid system; results were contrasted with similar data from studies with methylprednisolone, a classical glucocorticoid. Administration of tirilazad mesylate to rats, dogs and monkeys for 4 weeks had no effects at the highest doses tested on parameters assessed, including absolute peripheral blood lymphocyte counts, thymus or adrenal weights, circulating levels of cortisol, or lymphocyte proliferation response to phytohemagglutinin-P. Germinal centers in lymphoid tissues from dogs given high doses of tirilazad contained small numbers of macrophages with vacuolated cytoplasm but no other changes; lymphoid tissues in rats and monkeys given tirilazad were morphologically normal. Administration of methylprednisolone for a similar duration in rats and dogs at high dose levels was associated with increased death rates due to bacterial infections, markedly decreased peripheral blood lymphocyte counts and weights of thymus and adrenal glands, and prominent lymphoid atrophy as well as decreased circulating levels of cortisol. Female dogs infused for 10 days with a high dose of methylprednisolone had depression of the in vitro proliferation response of peripheral blood lymphocytes to phytohemagglutinin-P.

Animals↗