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Biomedical subjects

A Ruiz

Publications and source records attributed to A Ruiz.

At least 199 records · Page 11Linked to original sources
PubMed1996

RU486-treated rats show endocrine and morphological responses to therapies analogous to responses of women with polycystic ovary syndrome treated with similar therapies.

Administration of 4 mg of the antiprogestagen RU486 to 4-day-cyclic rats over 8 consecutive days starting on the day of estrus (Day 1) induced and anovulatory cystic ovarian condition with endocrine and morphological features similar to those exhibited in polycystic ovarian disease (PCO). To determine whether the RU486-treated rat responds in an analogous fashion to therapies similar to those that have been used to treat human PCO, RU486-treated rats were injection on Days 5 and 7 with 1) 1 mg of an LHRH antagonist (LHRHa), 2) 5 IU of human FSH (hFSH), 3) 2 mg of the antiandrogen flutamide (FLU), 4) 1 mg of the antiestrogen tamoxifen (TMX), or 5) 1 mg of the dopamine agonist bromocriptine (BRC). Controls were intact cyclic rats decapitated on estrus and rats injected with RU486 and the corresponding vehicles (saline or 70% ethanol) used with LHRHa, hFSH, FLU, TMX, and BRC injections. RU486-treated rats were decapitated on Day 9, and the serum concentrations of LH, FSH, prolactin (PRL), testosterone (T), and estradiol-17 beta (E2) were determined. Pituitary and ovary weight, number of follicular cysts, size of the corpora lutea, and rates of follicular growth and atresia were also noted. Finally, the ovulatory response to ovine LH (oLH) in rats treated with RU486 and injected with various doses of hFSH (5, 10, or 20 IU) was evaluated. While administration of LHRHa and of TMX decreased the serum concentrations of LH, T and E2 and the LH/FSH and T/E2, ratios, and injections of BRC and of FLU increased the serum concentration of LH and T, the administration of hFSH (10 IU) to RU486-treated rats increased only the serum levels of E2. All treatments decreased, though in different degrees, both the number of cysts and the rate of follicular atresia, and stimulated follicular growth. The positive effects on follicular growth and atresia were significantly higher in those rats injected with hFSH. Moreover, RU486-treated rats injected with different doses of hFSH ovulated in a dose-dependent manner in response to oLH. Rates deprived of the actions of progesterone through the administration of the antiprogestagen RU486 had 1) endocrine and morphologic alterations comparable to those observed in women with PCO, 2) analogous responses to therapies similar to those that have been used to treat human PCO, and 3) an ovulatory response to combined treatment with FSH and LH. These results establish the fundamental adequacy of using the RU486-treated rat as a PCO model.

Androgen Antagonists↗
PubMed1996

[A comparative study on the prognostic value of the nuclear expression of protein p53 vis-à-vis histopathology in colorectal cancer].

OBJECTIVE: To determine the predictive value of p53 nuclear overexpression in comparison with established prognostic pathological features in colorectal adenocarcinoma. PATIENTS AND METHODS: 61 patients operated on for cure between January 1989 an December 1991 were included. Expression of p53 protein was examined by immunohistochemistry in paraffin-embedded sections. Tumor localization, depth of bowel wall involvement, lymph nodes metastasis, vascular invasion and PCNA Labelling index were studied in all patients. RESULTS: Nuclear staining was detected in 27 (44.2%) cases. Positivity was more frequent in tumors with venous invasion and in rectal cancer. p53-positive tumours exhibited a higher likelihood of relapse and lower survival. After adjustment for the other covariates, p53 overexpression was the only factor showing independent prognostic significance on the risk of recurrence. None of the factors analysed evinced independent significant relationship with the risk of death. CONCLUSION: Nuclear p53 protein overexpression is closely related to the development of postoperative recurrences and has higher predictive value than standard pathological variables.

Adenocarcinoma↗
PubMed1996

Follicular and luteal progesterone synergize to maintain 5-day cyclicity in rats.

The length of the ovarian cycle in rat is determined by the duration of progesterone secretion from the corpora lutea (CL) during diestrus. The action of progesterone secretion from the preovulatory follicles on proestrus is also responsible for the cycle length in 4-day cyclic rats. To study whether follicular and luteal progesterone participate in the maintenance of 5-day cyclicity, the effects of the antiprogestagen RU486 (5 mg on proestrus or estrus) on estrous cycle length and on the serum concentrations of LH in 5-day cyclic rats and in 4-day cycle experimentally induced by the dopamine agonist CB154 (1 mg on estrus) were investigated. Furthermore, serum concentrations of progesterone on the day of ensuing ovulation were measured to see whether activation of the CL function after treatment with RU486 had occurred. Both 5-day and CB154-injected rats had a 3-day estrous cycle after RU486 on proestrus, while RU486 on estrus shortened by 1-day the estrous cycle length in 5-day but not in CB154-injected rats. Basal serum concentrations of LH increased and the LH surge decreased after RU486 treatment in both cycle types. Serum concentrations of progesterone rose only in 5-day rats injected with RU486. These results indicate that the actions of both follicular and luteal progesterone synergize in maintaining the length of the estrous cycle in 5-day cyclic rats and that functionally active CL increase progesterone production only under the action of a complete surge of prolactin.

Animals↗
PubMed1996

[Genetic factors study in family aggregation of schizophrenia in Santiago, Chile].

BACKGROUND: Genetic epidemiological studies indicate that genetic factors contribute to a familial aggregation of schizophrenia. The form of inheritance has not been elucidated but most studies have been done in Caucasian populations. AIM: To study the form of inheritance of schizophrenia in an urban population of Santiago, Chile, containing an admixture of Spanish origin individuals with Southamerican aborigines. SUBJECTS AND METHODS: Forty four randomly selected schizophrenic probands, 22 female, aged 28 to 48 years old, were studied. From them, an extensive genealogical reconstitution was performed. Probands and relatives were interviewed using the structured interview CIDI and DSM-III-R check-list. Schizophrenia was diagnosed using DSM-III-R criteria. Complex segregation analysis was done using Pointer program. RESULTS: The hypothesis of a multifactorial inheritance, without the participation of major genes, could not be rejected. Likewise, the major dominant and co-dominant gene forms of transmission could not be rejected. CONCLUSIONS: Our results show the participation of a major dominant locus and a multifactorial component in the inheritance of schizophrenia, as has been reported elsewhere.

Adult↗
PubMed1995

Characterization and quantification of full-length and truncated Na,K-ATPase alpha 1 and beta 1 RNA transcripts expressed in human retinal pigment epithelium.

We have characterized cDNA clones encoding the alpha 1 and beta 1 subunits of Na,K-ATPase produced in the human retinal pigment epithelium (hRPE). In addition to isolating clones corresponding to known sequences of Na,K-ATPase subunits, we report hitherto unknown forms of Na,K-ATPase with unique deduced amino acid (aa) sequences in their C-termini. Truncated cDNA sequences were found for both the beta 1 and alpha 1 subunits. While the beta 1 sequence is truncated by two aa residues at the C terminus, in the alpha 1 sequence 342 aa have been replaced by a unique sequence containing only 44 aa. Interestingly, this new C-terminal polypeptide shows sequence similarities to the Ca(2+)-ATPase and contains consensus sequence elements for phosphorylation and cell adhesion, suggesting expression of Na,K-ATPase subunits with unique functions. Using reverse transcription-polymerase chain reaction, RNA sequences for alpha 1, beta 1 and their corresponding truncated isoforms were quantified. 4.0 x 10(5) alpha 1 and 2.3 x 10(5) beta 1 molecules were found per ng of mRNA from hRPE. Much lower levels were detected for truncated alpha 1 and beta 1 (3.6 x 10(3) and 2.7 x 10(3) molecules/ng, respectively). These data corroborate the expression of truncated transcripts coding for unique aa sequences in hRPE, and suggest that factors other than alpha 1 and beta 1 mRNA levels regulate the equimolar accumulation of alpha and beta subunits in the plasma membrane.

Amino Acid Sequence↗
PubMed1995

Chromosome specific markers reveal conserved linkage groups in spite of extensive chromosomal size variation in Trypanosoma cruzi.

The karyotypes of three cloned stocks, CL Brener (CL), CA I/72 (CA) and Sylvio X10/7 (X10), of Trypanosoma cruzi were studied by pulsed-field gel electrophoresis followed by ethidium bromide staining and hybridization with 35 different probes, 30 of which identified single chromosomes. The chromosome-specific probes identified between 26 and 31 chromosomal bands in the three cloned stocks, corresponding to 20 unique chromosomes in CL and 19 in CA and X10. Considering the DNA content of the parasite, it was predicted that the markers recognise at least half of all T. cruzi chromosomes. A majority of identified chromosomes showed large differences in size among different strains, in some cases by up to 50%. Interestingly, CL had in general larger chromosomes than the two other studied cloned stocks. Several of the markers showed linkage and nine different linkage groups were identified, each comprising 2-4 markers. The linkage between the markers was maintained in 8 of the 9 linkage groups when a panel comprising 26 different T. cruzi strains representing major T. cruzi populations was tested. One linkage group was found to be maintained in some strains but not in others. This result shows that chromosomal rearrangements occur in the T. cruzi genome, albeit with a low frequency. Repetitive DNA, both non-coding and in one case coding, was more abundant in the cloned stock CL Brener than in CA and X10. The information presented will make it possible to select chromosomes for the construction of physical chromosomal maps required for the T. cruzi genome project.

Animals↗
PubMed1995

Effects of D-amphetamine administration on the release of endogenous excitatory amino acids in the rat nucleus accumbens.

1. The effects of acute D-amphetamine administration to rats on the release of endogenous excitatory amino acids from nucleus accumbens slices were studied. 2. D-amphetamine (5 mg/kg and 10 mg/kg; i.p.) significantly increased the spontaneous release of aspartate and glutamate from nucleus accumbens slices. 3. In contrast, D-amphetamine either produced no change or rather decreased K+ (40 mM)-evoked and N-methyl-D-aspartate (100 microM)-evoked release of aspartate and glutamate from the slices, respectively. 4. When D-amphetamine treated rats were pretreated with haloperidol, the effects of D-amphetamine on the spontaneous release of excitatory amino acids were not produced, whereas its effects on N-methyl-D-aspartate-evoked release remained unchanged. 5. These data suggest that amphetamine produces changes in excitatory amino acid-mediated transmission in the nucleus accumbens, that may play a role in amphetamine-induced behavioral or psychotomimetic effects.

Amphetamine↗
PubMed1995

Prediction of recurrence in B-C stages of colorectal cancer by p53 nuclear overexpression in comparison with standard pathological features.

This study investigated the predictive value of p53 nuclear overexpression on recurrence of colorectal adenocarcinomas compared with established prognostic pathological features. Sixty-one paraffin-embedded sections from primary tumours were examined by immunohistochemistry. Specific nuclear staining was detected in 27 (44.2%) cases. Positivity was more frequent in tumours with venous invasion (76.9%) (P = 0.06) and in rectal cancer (68.4%) (P = 0.06). After a median observation time of 46 months, p53-positive tumours exhibited a higher percentage of recurrence (40.7% vs 11.7%) (P = 0.03), and a higher likelihood of relapse at 5-year follow-up (46% vs 13%) (P = 0.006). Among the pathological variables analysed, only the extent of bowel wall invasion showed a relationship with recurrence. After adjustment for the other covariates in a Cox's regression model, p53 overexpression was the only factor showing independent prognostic significance (hazard ratio: 4.96; 95% Confidence Interval (CI): 1.47-16.71) (P = 0.012). The results of this study show that nuclear p53 protein overexpression has higher predictive value than standard pathological variables.

Adenocarcinoma↗
PubMed1995

The evolutionary history of Drosophila buzzatii. XXXII. Linkage disequilibrium between allozymes and chromosome inversions in two colonizing populations.

Chromosome polymorphism in Drosophila buzzatii is under selection but the genes responsible for the effect of the inversions of fitness are unknown. On the other hand, there is evidence for selection on several allozyme loci but the presence of paracentric inversions on the second chromosome, where most of the polymorphic loci are located, complicates the interpretation. Studies of the associations between allozymes and inversions are thus necessary to help understand the effect of selection at both the chromosomal and allozymic level. Until now this kind of information has only been available in D. buzzatii for two loci, Est-1 and Est-2, in Australian populations. Here we describe the genetic constitution of two Old World populations, Carboneras and Colera. Emphasis has been placed on the analysis of the linkage disequilibria between the second chromosome arrangements and three allozyme loci, Est-2, Pept-2 and Aldox, located on this chromosome. In addition, the recombination frequencies between the loci, and between the loci and the inversion breakpoints, have been estimated and a genetic map of the three loci has been produced. The two populations differ in allele and arrangement frequencies, as well as in the pattern of one-locus disequilibria. Est-2 and Aldox are associated with the second chromosome arrangements in both populations. On the other hand, Pept-2 is associated with the inversions in Colera but not in Carboneras. The gametic associations among the three loci are discussed taking into account the position of these loci on the chromosome map and the lack of recombination in the heterokaryotypes.

Animals↗
PubMed1995

The contribution of quantitative trait loci and neutral marker loci to the genetic variances and covariances among quantitative traits in random mating populations.

Using Cockerham's approach of orthogonal scales, we develop genetic models for the effect of an arbitrary number of multiallelic quantitative trait loci (QTLs) or neutral marker loci (NMLs) upon any number of quantitative traits. These models allow the unbiased estimation of the contributions of a set of marker loci to the additive and dominance variances and covariances among traits in a random mating population. The method has been applied to an analysis of allozyme and quantitative data from the European oyster. The contribution of a set marker loci may either be real, when the markers are actually QTLs, or apparent, when they are NMLs that are in linkage disequilibrium with hidden QTLs. Our results show that the additive and dominance variances contributed by a set of NMLs are always minimum estimates of the corresponding variances contributed by the associated QTLs. In contrast, the apparent contribution of the NMLs to the additive and dominance covariances between two traits may be larger than, equal to or lower than the actual contributions of the QTLs. We also derive an expression for the expected variance explained by the correlation between a quantitative trait and multilocus heterozygosity. This correlation explains only a part of the genetic variance contributed by the markers, i.e., in general, a combination of additive and dominance variances and, thus, provides only very limited information relative to the method supplied here.

Alleles↗
PubMed1995

Long oestradiol replacement in an oocyte donation programme.

The objective of this study was to optimize, in terms of endometrial receptivity (embryo implantation), the limits of unopposed administration of oestrogens beyond 35 days in an in-vitro fertilization (IVF) and ovum donation programme. Oocytes donated by 182 women undergoing IVF were distributed among 186 women treated by ovum donation. Five groups of recipients were established according to the duration of oestradiol valerate administration, in a 'prolonged follicular phase' protocol, before embryo replacement, employing oestradiol valerate at increasing doses up to 6 mg/day. Gonadotrophin-releasing hormone analogues (GnRHa) were simultaneously administered in ovulatory patients. The dosage of oestradiol valerate was maintained until oocytes were available for insemination and subsequent transfer. Donors and recipients were equally distributed among groups in terms of age and cause of infertility. There was no difference among groups in serum oestradiol concentration the day in which progesterone was added to obtain a secretory transformation of the endometrium. An analysis of the ovum donation cycles showed no difference among groups in pregnancy and implantation rates after the replacement of a similar number of embryos. Successful implantation was observed even after 100 days of unopposed oestradiol valerate administration. Break-through bleeding increasingly appeared according to the duration of oestrogen replacement. These clinical observations provide evidence that the concept of 'prolonged follicular phase' oestrogen replacement for ovum donation can be maintained, at least as long as 15 weeks. However, because of the high (> 44%) incidence of break-through bleeding after 9 weeks, it is advisable to stop oestrogen treatment at this point.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Exploring the mechanism(s) of endometriosis-related infertility: an analysis of embryo development and implantation in assisted reproduction.

Several retrospective analyses of our in-vitro fertilization (IVF) and oocyte donation programmes have been carried out in an attempt to gain clinical knowledge of the factors implied in the aetiology of endometriosis-associated infertility. In a first approach, a comparison was made of the IVF outcome between 96 cycles in 78 patients with tubal infertility and 96 more cycles in 59 women with endometriosis. The results indicate that endometriosis patients had a poor IVF outcome in terms of a reduced pregnancy rate per cycle (P < 0.0004), a reduced pregnancy rate per transfer (P < 0.002) and a reduced implantation rate per embryo replaced (P < 0.003). In a second study, we addressed the analysis of patients undergoing oocyte donation. The results showed that patients with this disease have the same chances of implantation and embryo development in vivo as other recipients when the oocytes come from donors without known endometriosis. However, when the results of oocyte donation were classified according to the nature of the oocytes donated, patients who received embryos derived from endometriotic ovaries showed a significantly (P < 0.05) reduced ability to implant compared with the remaining groups. In a third approach, we evaluated embryo development in vitro when women with and without endometriosis underwent IVF and embryo replacement 72 h after oocyte retrieval. We observed a significantly (P < 0.04) reduced number of blastomeres in embryos from endometriosis patients compared with controls, as well as an increased (P < 0.05) incidence of arrested embryos in vitro. Taken together, these observations suggest that infertility in endometriosis patients may be related to alterations within the oocyte which, in turn, result in embryos of lower quality, as demonstrated in our IVF programme, and a lower ability to implant, as shown in the oocyte donation model.

Embryo Implantation↗
PubMed1995

Transmission of cervical human papillomavirus infection by sexual activity: differences between low and high oncogenic risk types.

Not all studies have proven that cervical human papillomavirus (HPV) infection is a sexually acquired condition. Determinants of HPV infection were analyzed in a survey of 718 asymptomatic women in northeastern Brazil. HPV DNA was detected and typed by polymerase chain reaction. HPV types were classified into low- and high-risk groups on the basis of their association with cervical carcinomas. Overall HPV prevalence (18.3%) was moderately associated with age at first intercourse (P = .111, trend) and number of lifetime sex partners (P = .005, trend). However, separate analyses by risk revealed different degrees of association with sexual activity. Except for a positive association with multiple partners among women < 40 years old (P = .034, trend), infection with low-risk types (9.7%) was not correlated with sexual behavior. On the other hand, infection with high-risk HPV types (11.6%) was strongly and independently associated with both multiple partners (P = .009, trend) and age at first intercourse (P = .007, trend) in all age groups.

Adult↗
PubMed1995

Follicular and luteal progesterone play different roles synchronizing pituitary and ovarian events in the 4-day cyclic rat.

Administration of 4 mg of the antiprogestagen RU486 to 4-day cyclic rats during proestrus induced a 1-day shortening of the ovarian cycle, a reduction in ovulatory rate that was reversed by an injection of exogenous human (h)FSH in the evening of proestrus, and the absence of the LH-inhibiting effect of exogenous estradiol resulting in a 24-h advancement of the preovulatory LH surge. These effects were not present when RU486 was injected during estrus. RU486 injected during either proestrus or estrus increased serum levels of LH and estradiol-17 beta in diestrus and reduced the magnitude of the preovulatory surge of gonadotropins. Only rats treated with RU486 during estrus showed increased follicular size and acceleration of oocyte maturation on proestrous afternoon. These results demonstrate that in 4-day cyclic rats receiving an injection of RU486 during proestrus, the low ovulatory rate is a consequence of a reduced secondary FSH surge-induced follicular recruitment in the afternoon of estrus and that the shortening of the estrous cycle is the result of an advanced desensitization to the negative feedback of estradiol on LH secretion. Furthermore, since the administration of RU486 during proestrus blocks both follicular and luteal progesterone actions whereas injection during estrus blocks only luteal progesterone actions, we suggest that, in 4-day cyclic rats, the actions of progesterone during diestrus retard maturation of follicles via the lowering of serum LH concentrations and that the actions of progesterone in proestrous evening delay the desensitization to the negative estrogen feedback on LH secretion.

Animals↗
PubMed1995

Inflammatory and infectious processes of the cervical spine.

This article discusses infectious and inflammatory processes of the cervical spine. Major emphasis is placed on infectious discitis/osteomyelitis and epidural abscess, particularly the epidemiologic, bacteriologic, pathophysiologic, and clinical aspects, as well as the major role played by magnetic resonance imaging and other imaging modalities used in the detection and diagnosis of these processes.

Arthritis, Rheumatoid↗