Biomedical subjects

H Cárdenas

Publications and source records attributed to H Cárdenas.

At least 37 records · Page 2Linked to original sources

PubMed1994

Low flow veno-venous ECMO: an experimental study.

Clinical use of extracorporeal membrane oxygenation (ECMO) and carbon dioxide removal (ECCO 2R) have become well established techniques for the treatment of severe respiratory failure; however they require full cardiopulmonary bypass, representing major procedures with high morbidity. We theorized the possibility of an efficient low flow veno-venous extracorporeal membrane gas exchange method. Four mongrel 12 kg dogs were submitted to veno-venous extracorporeal membrane gas exchange via a jugular dialysis catheter using a low flow (10 ml/min) roller pump and a membrane oxygenator for a period of four hours. Respiratory rate was set at 4 breaths/min with a FiO 2 of 21% and ventilatory dead space was increased. Adequate gas exchange was obtained (pO 2139, pCO 224, Sat 99.4%), without major hemodynamic changes or hematuria. Our results demonstrate the feasibility of a low flow, less aggressive system. Further research should be considered.

Animals↗

PubMed1994

Bioequivalence study for diazepam commercial tablets in psychiatric patients.

The bioequivalence of three different commercial diazepam tablets (5 mg) using the innovator product (Valium, Roche) as a reference was evaluated in eight psychiatric patients, following a multiple-dose regimen (5 mg t.i.d.). Each patient received the four treatments sequentially according to a Latin square design, with balance for first residual effect. Blood samples were taken once the steady state of the drug had been reached, and the plasma levels were determined using a HPLC method. No statistical differences were found in diazepam steady-state levels after the administration of the four formulations, indicating that they could be considered equivalent.

Administration, Oral↗

PubMed1993

Luteal function and blastocyst development in ewes following treatment with PGF(2)alpha and GnRH.

Luteal function and blastocyst development were compared in ewes treated with GnRH (100 mug) on Day 1 (Day 0 = day of estrus) or in ewes previously induced into estrus with PGF(2)alpha. In Experiment 1, the duration of estrous cycles of ewes previously treated with PGF(2)alpha were longer (P<0.06) than those that received PGF(2)alpha plus GnRH, GnRH alone, or remained untreated (control) ewes. Progesterone concentrations were lower (P<0.07) on Day 1 and higher (P<0.01) on Days 16 and 17 of the estrous cycles following PGF(2)alpha treatment relative to those of the natural (control) cycles. In Experiment 2, blastocysts of ewes treated with PGF(2)alpha were less developed (P<0.06) by Day 13 of pregnancy than those of the control ewes. The GnRH treatment did not influence any of these characteristics. Treatment with PGF(2)alpha delayed luteal formation during the subsequent estrous cycle, increased the duration of the estrous cycle and slowed the rate of blastocyst development relative to GnRH-treated and untreated ewes.

Journal Article↗

PubMed1993

Effect of time of mating relative to ovulation on morphological diversity of swine blastocysts.

The effect of time of mating relative to ovulation on the amount of embryonic diversity was investigated in 37 mature crossbred gilts. Ovulation was induced by injecting proestrous gilts with 1000 IU of hCG. Gilts were naturally mated once at 24-32 (control), 41, or 43 h after hCG injection (n = 10, 9, and 18, respectively). Blastocysts were collected surgically 288 h post-hCG from gilts mated at 24-32 h post-hCG, from those mated at 41 h post-hCG, and from 8 of those mated at 43 h post-hCG. Collection of blastocysts was performed at 295 h in 10 gilts mated at 43 h post-hCG. Blastocysts within the ranges 1.0-4.0, 4.5-7.0, 7.5-10.0, 10.5-15.0, and 15.5-40.0 mm and those > 40.0 mm were classified morphologically as small, medium, and large spheres and as ovoidal, tubular, and filamentous, respectively. Blastocysts were incubated for 6 h to quantify secretion of estradiol-17 beta (estradiol). Morphological diversity (standard deviation of size) did not differ among blastocysts of treatment groups. Delaying the time of mating reduced (p < 0.07) the subsequent size and estradiol secretion of blastocysts. Waiting until 295 h after hCG to evaluate blastocysts of gilts mated at 43 h resulted in blastocysts size and estradiol secretion similar to that of conception of controls. Estradiol secretion by medium and large spherical blastocysts of gilts mated at 43 h post-hCG and evaluated at 288 h was lower (p < 0.05) than that by blastocysts of the same classifications from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

[Nutritional evaluation of sweet potato cultivars Ipomea batata (L.) Lam used in bread as partial substitute of wheat flour].

Four hundred and forty entries of sweet potato tubers from the International Potato Center were evaluated for chemical characteristics related to nutritional value. Dry matter range in the group was 15 to 45g/100g. The native entries DLP 2393, DLP 1120, DLP 2312, DLP 1908 and the foreign RCB 361F were selected for use in bread manufacture. Their average dry matter and crude protein was 38.5 and 9.2% respectively. Sweet potato bread was made replacing 30% of wheat flour with grinded sweet potato tubers. This bread had 11.0% crude protein in dry matter basis which were the same for bread made of wheat flour. There were no differences in organoleptic characteristics or protein quality (Apparent biological value: 37 vs 42%; apparent digestibility: 81 vs 80%; net protein utilization: 33 vs 39%) between sweet potato or full wheat flour breads respectively.

Bread↗

PubMed1992

Relative contributions of anovulation and luteal phase defect to the reduced pregnancy rate of breastfeeding women.

OBJECTIVE: To evaluate the contribution of anovulation and luteal phase defects to lactational infertility. DESIGN: Prospective longitudinal follow-up. SETTING: Outpatient clinic. SUBJECTS: Forty-nine women fully nursing and amenorrheic on day 75 postpartum and 25 cycling, interval non-nursing women. INTERVENTIONS: Plasma prolactin, luteinizing hormone, estradiol (E2), and progesterone (P) levels twice a week up to the second postpartum menses. MAIN OUTCOME MEASURES: Ovulation rate and endocrine profile of the menstrual cycles. RESULTS: Ovulation rates were 37% and 97% at 6 and 12 months postpartum; 67% of ovulations occurred in amenorrhea. The luteal phase was shorter, and E2 and P levels were lower in lactating women than in non-nursing women. These parameters were closer to normal in the second cycle than the first, in spite of active nursing. The risk of ovulation and pregnancy in amenorrhea was 27.7% and 0.9% at month 6 postpartum. After the first menses, these risks were 93% and 7%, respectively. CONCLUSION: The abnormal endocrine profile of the first luteal phase offers effective protection to women who ovulate during lactational amenorrhea within the first 6 months after delivery. Later luteal phases are improved and women are at risk of pregnancy.

Adolescent↗

PubMed1991

Contraceptive efficacy of lactational amenorrhea in urban Chilean women.

The contraceptive efficacy of breastfeeding was assessed in 236 healthy urban women who were followed at monthly intervals during the first postpartum year. Proportional hazard models were used to evaluate the influence of time postpartum, menstrual status and breastfeeding pattern upon the risk of pregnancy. Time and menstrual status had a highly significant effect on this risk. Those women who remained in amenorrhea had cumulative probabilities of pregnancy of 0.9% and 17% at 6 and 12 months postpartum, respectively. In those who recovered menstrual cycles, the risk rose to 36% and 55% at 6 and 12 months, respectively. Milk supplementation also increased significantly the risk when considered alone but not when time and/or menstrual status were included in the analysis. However, amenorrheic women who introduced bottle feeding, had a higher risk of pregnancy after 6 months postpartum than those who remained fully nursing. The analysis was unable to detect a significant influence of the nursing frequency. The results confirm that lactational amenorrhea is an effective contraceptive during the first six months postpartum. The first postpartum bleeding marks a great increase in the risk of pregnancy. Supplementation also increases the risk, particularly in amenorrheic women.

Adult↗

PubMed1991

Mechanism of action of progesterone as contraceptive for lactating women.

Progesterone vaginal rings releasing 5-15 mg/day were tested as a contraceptive for lactating women. Progesterone plasma levels achieved ranged from 10 to 20 nmol/L. Pregnancy rates at the end of the year were less than 1% and 39% in treated (n = 210) and untreated (n = 236) nursing women, respectively. Around 70% of treated and 30% of untreated women were amenorrheic at 8 months post partum. The endocrine profile during the first 8 months post partum was assessed in 36 treated and 28 untreated nursing women. Pre- and postsuckling prolactin (PRL) levels were measured at 1600 hr at fortnightly intervals and E2 determinations and ovarian ultrasound were performed twice a week. Prolactin increases in response to suckling and postsuckling PRL levels were higher, E2 levels were lower, and follicular growth was arrested at earlier stages in progesterone-treated than in untreated women. The pattern observed in progesterone-treated women was similar to that in prolonged lactational amenorrhea. This suggests that progesterone increases the sensitivity of the breast-hypothalamic-pituitary system to suckling and reinforces the mechanism of lactational infertility.

Breast Feeding↗

PubMed1991

Early difference in the endocrine profile of long and short lactational amenorrhea.

The endocrine profiles associated with long and short lactational amenorrhea were assessed in a longitudinal study in which morning blood samples were drawn in 48 women from the first postpartum month until the recovery of ovulation and in a cross-sectional study in which the samples were drawn throughout 24 h at the end of the third postpartum month in 10 fully nursing and amenorrheic women. PRL, LH, FSH, estradiol (E2), progesterone, cortisol, and dehydroepiandrosterone sulfate were measured. In both studies we detected a smaller PRL increase in response to suckling (P less than 0.001) and higher E2 levels (P less than 0.001) in nursing women who ovulated within 6 months postpartum compared to those in women who did not. Such differences were observed early after delivery when all women were fully nursing and amenorrheic. These results suggest some probable sources of variability in the duration of lactational amenorrhea in our population. The greater PRL response to suckling associated with longer amenorrhea may be due to higher sensitivity of the breast-hypothalamus-pituitary system or a stronger suckling stimulus in this group. Differences in plasma E2 levels between longer and shorter periods of amenorrhea may reflect dissimilar endogenous production, intake, or clearance of estrogens.

Adult↗

PubMed1991

[Influence of basal and post-feeding prolactin levels on amenorrhea during breast feeding].

Forty five women, with exclusive breastfeeding were studied, (the objective was) to explore the relationship between: basal plasma prolactin (PRL) levels and post-suckling with the duration of postpartum amenorrhea. Blood samples for measurements of PRL were taken at the third month postpartum, before an episode of suckling and 30 minutes after the suckling was initiated. The average level of basal PRL was 1,033 +/- 113 mIU/L (mean +/- SE). Women who presented long periods of amenorrhea, had an increase of the basal PRL in 632 mIU/L (X), compare to those women who had their menses before 180 days postpartum (p = 0.036) women with longer amenorrhea (p = 0.06). However there were no relationship between the menses at the sixth month postpartum and the increase of post-suckling PRL (delta PRL). In this study it was found that the levels of basal PRL had correlation with the duration of the amenorrhea, in women with exclusive breastfeeding.

Adult↗

PubMed1989

A longitudinal study on cortisol, prolactin and thyroid hormones in users of Norplant subdermal implants or a copper T device.

A longitudinal study was undertaken to assess PRL, cortisol, TSH, T3 and T4 levels in NORPLANT implant users (n = 22) and Copper T users (n = 20). Participants were healthy women with no contraindication for hormonal contraception. Samples were drawn at 0930 to 1000 h twice pretreatment and at month 2, 4, 6, 12, 24 and 36 after insertion. At the second treatment month, a second sample was obtained at 1600 h to assess cortisol diurnal variation. Hormones were measured by RIA. Values for all hormones were similar in Norplant and Copper T users. No significant changes occurred throughout the study period. Elevated PRL levels (greater than 500 mU/1) were found in three women from each group before and during treatment but no clinical evidence of hyperprolactinemia was detected. The results of this study reassure that long-term use of NORPLANT implants do not impair plasma levels of cortisol, prolactin and thyroid hormones.

Adult↗

PubMed1989

Circadian variation of basal plasma prolactin, prolactin response to suckling, and length of amenorrhea in nursing women.

The circadian pattern of plasma PRL levels and the PRL response to suckling were examined at various times during the first postpartum year and related to the length of lactational amenorrhea. Ten healthy women whose infants were breast-fed exclusively and who were amenorrheic 3 months postpartum were studied 3, 6, and 9-11 months postpartum. The women and their babies were admitted to a metabolic unit for 48 h. On the second day, blood samples were drawn at 2-h intervals for 26 h starting at 0800 h and also 10 and 30 min after the initiation of six of the nursing episodes. During the three postpartum periods, there was a circadian rhythm of basal plasma PRL concentrations; the peak concentrations occurred between 2400-0600 h. Suckling induced a significant rise in plasma PRL levels at all hours except 0800 h. There was a positive correlation between the duration of the nursing episode and the suckling-induced PRL increase at 30 min. Both the basal plasma PRL levels and the PRL responses to suckling diminished with time after delivery. This trend was less evident at 0400 h and was not fully explained by changes in the nursing pattern. The five women in whom menstrual cycles resumed before day 180 postpartum had lower basal and suckling-induced plasma PRL levels than the women who had amenorrhea for a longer period. This difference was present in the third month, when all women were amenorrheic and fully nursing and when the frequency and duration of nursing episodes and infant growth rates were similar. The results indicate that comparable nursing patterns may be associated with different plasma PRL levels, which are associated with different lengths of lactational amenorrhea. An early difference in the sensitivity of the breast-hypothalamus-pituitary system to suckling may explain the differences in the duration of lactational amenorrhea, which are not dependant on the breastfeeding pattern. The magnitude of the PRL response to suckling may predict the likelihood of recovering ovarian function during lactation.

Adult↗

PubMed1989

Effect of oestradiol delivered from a perioviducal device on ovum transport in mice.

Silastic devices impregnated with oestradiol and blank devices were placed around both oviducts and around skeletal muscle bundles in the forelegs to attain local and systematic delivery, respectively. Another group of mice received an oestradiol-impregnated device around one oviduct and a blank device in the contralateral oviduct. Implantation of blank devices around the oviducts and in the forelegs did not alter ovum transport. Devices impregnated with oestradiol placed around both oviducts produced a dose-dependent delay of ovum transport, which was more pronounced than the effect of devices located in the forelegs. Oviducts receiving an oestradiol-loaded device had a larger retention of ova than did the contralateral oviducts receiving a blank device. These results demonstrate a direct action of oestradiol upon the oviduct to delay ovum transport in the mouse.

Animals↗

PubMed1988

Inhibition of sperm migration, fertilization and implantation in rats by precoital intrauterine administration of gossypol or nonoxynol-9.

The effects of precoital intrauterine administration of Gossypol, Nonoxynol-9 or p-Aminobenzamidine on reproductive function were investigated in rats. The drugs were instilled in one uterine horn in the evening of proestrus prior to caging with a fertile male. The opposite side was similarly treated with the vehicle and served as control. Animals were killed in the morning following mating to assess the number of spermatozoa at the site of fertilization or on days 2-3 of pregnancy to determine the proportion of penetrated oocytes or on day 12 to count implanted embryos. Gossypol 0.05 to 5 mg or Nonoxynol-9 0.1 - 10 microliter reduced the number of spermatozoa reaching the ampullae and the number of penetrated oocytes in a dose-dependent fashion. At the highest dose both compounds prevented pregnancy exclusively in the treated side. p-Aminobenzamidine at a dose of 10 mg failed to affect the proportion of penetrated eggs found on days 2 or 3 of pregnancy. The results indicate that the rat bioassay is suitable to screen agents that can affect sperm function or viability since it can discriminate between drugs and doses and disclose differential effects upon sperm migration and fertilizing capacity.

Animals↗

PubMed1988

Clearance of levonorgestrel from the circulation following removal of NORPLANT subdermal implants.

The disappearance of levonorgestrel from plasma after the removal of NORPLANT subdermal implants was studied in 12 women who had been treated from 5.5 to 78 months. The existence of one or two half-lives for the rate of disappearance was assessed. The influence of body weight, body fat and length of treatment upon levonorgestrel clearance was studied through stepwise regression analysis. It was found that the levonorgestrel decay rate after implant removal can be entirely accounted assuming one half-life of 42 +/- 16 h (mean +/- SD; range 13 to 62 h). Stepwise regression analysis showed that levonorgestrel half-life is positively correlated with body weight and not significantly correlated with the length of treatment or body fat. It is concluded that, after long-term administration of levonorgestrel via subdermal implants, the major part of the steroid is cleared from plasma within 96 h and that only trace amounts are detected in the following days.

Adult↗

PubMed1988

A study on the feasibility of suppressing ovarian activity following the end of postpartum amenorrhoea by increasing the frequency of suckling.

The aim of the study was to test the effect of increasing the frequency of breastfeeding upon ovarian function following the end of postpartum amenorrhoea. Women exclusively breastfeeding (n = 14) who experienced their first postpartum menstruation between the third and fifth month after delivery were randomly allocated to an experimental (n = 7) and a control (n = 7) group and studied during the next two cycles. Women in the experimental group agreed to increase the number of breastfeeding episodes per day throughout the second cycle. Blood samples were drawn twice a week from the first to the third postpartum menstruation for prolactin, oestradiol and progesterone determinations. The number of breastfeeding episodes per day and night and the length of each episode were recorded daily. An average frequency of 11 nursing episodes per 24 h was reported during the first study cycle in both groups. The experimental group increased by 50% the breastfeeding frequency after the second menstruation while the control group kept its spontaneous feeding pattern. The increase of suckling frequency occurred mainly during day hours. The total breastfeeding time per 24 h was not increased. The length of the menstrual cycle was not altered by the increased suckling frequency. The endocrine pattern differed neither between the first and second cycle of the experimental group nor between the experimental and control group, with the exception of PRL levels which were higher in the experimental group throughout both cycles. Twenty cycles (71%) showed progesterone values compatible with ovulation (greater than 9.5 nmol/l). The highest progesterone values and the highest oestradiol values observed in the ovulatory cycles of lactating women were within the range found in non-nursing fertile women. Plasma levels of PRL were significantly elevated in all cycles but one, in comparison with PRL levels in non-nursing women. It is concluded that if cyclic ovarian function is reestablished early in fully nursing women, a mere increase in the number of breastfeeding episodes, without augmenting total suckling time and the frequency of nocturnal episodes, does not provide a sufficient stimulus to resuppress the pituitary-ovarian axis.

Adult↗

PubMed1987

Recovery of fertility and outcome of planned pregnancies after the removal of Norplant subdermal implants or Copper-T IUDs.

The recovery of fertility after discontinuation of NORPLANT implant use was assessed in ninety women who stated a desire for a new child at the time of removal. Three subjects were lost to follow-up after removal. The cumulative probability of conception in the remaining 87 women was 25, 49, 73 and 86 percent at one, three, six and twelve months after removal, respectively. Nine observations were censored either because of the use of a contraceptive method soon after removal of the implants (n = 7) or separation (n = 2). All other cases were pregnant at the end of two years with exception of three subjects where a male factor for infertility was present. There was no significant correlation between the length of NORPLANT use and the length of the interval from removal to conception. A significantly higher frequency of intervals longer than 6 months was observed among women older than 30 years as compared to younger women. Pathology during pregnancy was cholestasia (n = 5), hypertension (n = 1) and gestational diabetes (n = 1). The outcome was term delivery in 59 cases, premature delivery in 4 cases, and spontaneous abortion in 7 cases. One woman is still pregnant and the outcome is unknown in 4 cases. One premature infant died. A contemporary control group of Copper T users enrolled under the same criteria as NORPLANT implant users provided 44 women who had the device removed to become pregnant. The cumulative probability of pregnancy was 27, 69, 84 and 89 at one, three, six and twelve months and all were pregnant by the end of the second year. Six censored observations occurred because of the use of another contraceptive method after removal (n = 3) or loss to follow-up (n = 3). The outcome of pregnancy was term delivery in 23 cases and abortion in 7 cases. Recovery of fertility occurred at a normal rate after NORPLANT implant removal and the incidence of problems detected in the ensuing pregnancy were within the expected range for Chilean women.

Age Factors↗

PubMed1983

Accommodation of skeletal muscle in rats under hypoxic conditions induced by tourniquet.

Resting membrane potential (RMP) and indexes of accommodation (IA) were obtained from the brachioradialis muscle in rats subjected to 2 or 5 h of bilateral hindlimb tourniquet. The results showed a highly significant increase in muscular IA with a return to the control values for the rats with 2 h of tourniquet, while the increased in the IA is maintained all the survival period in the rats with 5 h of tourniquet. The velocity of increasing of the IA bears a direct relationship to the outcome of the injury. A decrease in the RMP of the brachioradialis muscle and an increase in the extracellular K+ and H+ was also observed. The early differences in the behavior of the accommodation parameter allowed a clear differentiation of the rats which survived the tourniquet shock from those who finally died.

Animals↗