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S Mejía

Publications and source records attributed to S Mejía.

15 recordsLinked to original sources
PubMed1999

Changes in the expression of neurohypophyseal prolactins during the estrous cycle and after estrogen treatment.

Estrogens are recognized regulators of the expression of neurohypophyseal hormones and of anterior pituitary prolactin (PRL). Here we have investigated whether the levels of PRL mRNA and of 23 and 14 kDa PRL variants present in the hypothalamo-neurohypophyseal system change during the estrous cycle or in response to estrogen treatment. The reverse transcription polymerase chain reaction (RT-PCR) was performed to examine PRL mRNA expression in isolated paraventricular (PVN) and supraoptic (SON) hypothalamic nuclei. In both nuclei PRL mRNA levels appeared higher in cycling females than in male rats, with the highest level occurring at estrus. This increase may involve estrogen action, since estrogen administration to ovariectomized rats was associated with apparently higher PRL mRNA levels in both the PVN and SON. Expression of the PRL gene at these sites may occur via both transcriptional factor Pit-1-dependent and -independent mechanisms. RT-PCR detected the mRNA for Pit-1 in the PVN but only at estrus. The concentration of the 23 kDa immunoreactive PRL determined in the neurohypophysis was significantly higher during estrus and after estrogen treatment. However, no difference was detected in the levels of the neurohypophyseal 14 kDa PRL-like fragment along the estrous cycle nor after estrogen administration. This lack of parallelism between neurohypophyseal PRLs could relate to an estrogen-induced inhibition of the proteolysis of 23 kDa PRL at this site, since estrogen treatment reduced the activity of neurohypophyseal proteolytic enzymes able to cleave PRL. Altogether our results are consistent with estrogens having a stimulatory effect on PRL gene expression in the hypothalamo-neurohypophyseal system and a concomitant inhibitory action on PRL proteolysis at this site.

Animals↗
PubMed1997

Immunoreactive prolactin forms colocalize with vasopressin in neurons of the hypothalamic paraventricular and supraoptic nuclei.

The prolactin (PRL) gene is expressed in the hypothalamo-neurohypophyseal system as revealed by the detection of the PRL mRNA and of PRL-like immunoreactive and biologically active proteins in hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei and in the neurohypophysis. We have investigated the distribution of cells containing PRL-like molecules in the PVN and SON by immunocytochemistry with a specific antiserum directed against the 16-kD N-terminal fragment of PRL. PRL-positive cells were found to be concentrated throughout the ventral SON and in the lateroposterior region of the PVN. The cellular distribution of PRL-immunoreactive cells resembled more closely that of vasopressin (VP) than that of oxytocin magnocellular neurons. Moreover, double immunofluorescence labelling, followed by confocal microscopy, indicated the coexistence of PRL- and VP-related antigens within the same neurons of the PVN and SON. Pre-embedding immunoperoxidase on the ultrastructural level showed a PRL-like product in granular-type particles within the neural soma and projections in the SON and PVN. These findings are consistent with the expression and secretion of PRL-like molecules by vasopressinergic neurons of the hypothalamo-neurohypophyseal system.

Animals↗
PubMed1997

Role of endomyocardial biopsy in the diagnosis of chronic rejection in human heart transplantation.

To assess the pathologic findings observed in the setting of post-transplant graft atherosclerosis, we have studied 18 endomyocardial biopsies (EMB) from 18 heart-transplanted patients collected at the same time that a coronary angiography (CA) showed changes consistent with graft atherosclerosis. Twenty-two EMB from patients with heart transplant with normal CA were used as controls. In spite of the small size of the sample, the number of acute rejection (AR) episodes correlated with the appearance of graft atherosclerosis (p < 0.001). Heart biopsies in graft atherosclerosis showed myointimal proliferation, thickening and folding of the wall of precapillary arteries, myocyte hypertrophy, and interstitial and perivascular fibrosis. Type III and type IV collagen, laminin, and fibronectin were increased in areas of interstitial and perivascular fibrosis, as well as in the vessel's wall. Fibronectin accumulation was more evident in the subendothelium and inner media of affected vessels. These changes were never found all together in control biopsies. Even though the inespecificity of some of those findings, we conclude that chronic graft atherosclerosis in a heart transplant may be suspected by endomyocardial biopsy when most of these alterations are seen together, especially if small precapillary arteries are present in the specimen.

Acute Disease↗
PubMed1995

A 14-kilodalton prolactin-like fragment is secreted by the hypothalamo-neurohypophyseal system of the rat.

The recently described expression of the PRL gene, and the occurrence of a 14-kilodalton (kDa)PRL-like immunoreactive protein in the hypothalamo-neurohypophyseal system of the rat have raised the possibility that PRL variants are released from neurohypophyseal terminals into the blood. In this study, we investigated the local production of a hypothalamo-neurohypophyseal 14-kDa PRL-like protein by showing an independent origin from adenohypophyseal PRL. No 14-kDa PRL-like protein was detected in adenohypophyseal extracts by Western blots, whereas chronic hypophysectomy produced no change in the immunocytochemical detection of PRLs in supraoptic and paraventricular magnocellular neurons. In addition, a 14-kDa immunoreactive PRL-like protein was released into the medium by incubated neurohypophyseal lobes. Western blot analysis showed that significantly more of this 14-kDa protein was released into calcium-containing medium (1.8 mM) than into calcium-free medium. Furthermore, depolarizing concentrations of potassium (56 mM) increased by 3-fold the release of immunoreactive PRL by incubated hypothalamo-neurohypophyseal explants. In addition, a 14-kDa PRL-like antigen was detected in the circulation of the rat by Western blot analysis. These results are consistent with the local synthesis and calcium-dependent release of neurohypophyseal PRL-like proteins that include a predominant 14-kDa form.

Animals↗
PubMed1994

The prolactin gene is expressed in the hypothalamic-neurohypophyseal system and the protein is processed into a 14-kDa fragment with activity like 16-kDa prolactin.

The 23-kDa form of prolactin (PRL) has been proposed to function as both a mature hormone and a prohormone precursor for different uniquely bioactive forms of the molecule. We have shown that the 16-kDa N-terminal fragment of PRL (16K PRL) inhibits angiogenesis via a specific receptor. In addition, 16K PRL stimulates natriuresis and diuresis in the rat, and kidney membranes contain high-affinity specific binding sites for this PRL fragment. 16K PRL can be derived from an enzymatically cleaved form of PRL (cleaved PRL). With the use of a specific 16K PRL antiserum, we have localized a 14-kDa immunoreactive protein in the paraventricular and supraoptic nuclei of the hypothalamus and in the neurohypophysis. Reverse transcription-polymerase chain reaction of RNA from isolated paraventricular nuclei showed the expression of the full-length PRL mRNA. The neurohypophysis was found to contain the enzymes that produce cleaved PRL, small amounts of PRL, and cleaved PRL. Medium conditioned by neurohypophyseal cultures, enriched with the 14-kDa immunoreactive protein, has antiangiogenic effects that are blocked by the 16K PRL antiserum. These results are consistent with the expression of PRL in the hypothalamic-neurohypophyseal system, and the preferential processing of the protein into a 14-kDa fragment with biological and immunological properties of 16K PRL.

Animals↗
PubMedDate not supplied

Unsuccessful pericardiocentesis for cardiac tamponade during angiocardiography with nonionic contrast material.

Cardiac tamponade secondary to ventricular wall perforation is one of the possible complications of right-sided as well as left-sided cardiac catheterization. Ventriculography was performed on a patient with obstructive cardiomyopathy using a nonionic contrast medium. During the procedure, the right ventricle was accidentally perforated and the patient developed cardiac tamponade. Pericardiocentesis was unsuccessful and surgical drainage was needed after the patient developed progressive hemodynamic deterioration. At surgery, pericardial thrombus was found. We consider the reason for failure of pericardiocentesis was rapid coagulation of the extravasated blood in connection with nonionic contrast material.

Aged↗
PubMedDate not supplied

[A system of multidimensional behavior assessment. A scale for parents of children from 6 to 11 years of age. Colombian version].

INTRODUCTION: Behavioral Assessment System for Children (BASC) has demonstrated to be useful in the diagnosis of Attention Deficit Disorder (ADD). PATIENTS AND METHODS: A randomized sample of 120 children, 6 to 11-year-old, participants from the school of the city of Medellín, Colombia, was selected. The sample was stratified by sex and two socioeconomic status (SES). Parents were asked to answer the BASC Parent Rating Scale (PRS) 6-11, authorized Spanish version. RESULTS: Cronbach's alpha coefficient was 0.85 for the clinical scale (9 items). It was 0.75 for the Adaptive Scale (3 items). A scale designed with 4 items to assess ADD (hyperactivity, attention problems, aggression, and conduct problems) showed an alpha coefficient of 0.82. Male children scored significantly higher than female (ANOVA, p < 0.05) in hyperactivity, conduct problems, and atypicality. Children from low SES scored significantly higher than children of high SES on the most of clinical measures (p < 0.05) and lower on the three adaptive measures. Cluster analysis selecting six clusters found a prevalence of 61.6% for normal male children. In the total sample there were a 4% at risk of DDA type II (inattentive) and 14% at risk of DDA type I (combined). CONCLUSIONS: BASC PRS (6-11) showed reliability and validity to assessing the behavior in Spanish speaking Colombian children.

Attention Deficit Disorder with Hyperactivity↗
PubMedDate not supplied

[Use of multidimensional scale for parents of children aged 6 to 11 for the diagnosis of attention deficit with hyperactivity].

INTRODUCTION: The BASC is a multidimensional approach to evaluate the child behavior and it has been validated on the diagnosis of ADD/+H in North American children. OBJECTIVE: Validating BASC-PRS 6-11 on the diagnosis of ADD/+H. PATIENTS AND METHODS: We selected 25 male DSM IV-ADD/+H (combined type), 6 to 11-years-old children, and 25 age, gender, and socioeconomic status matched controls. Mean ages of both groups 8.16 (1.5), schooling of controls 2.64 (1.4), and cases 2.6 (1.9). RESULTS: On the Clinical Scale ADD/+H children had significant (Anova p < 0.01) higher scores in hyperactivity, conduct problems, and attention problems. On the Adaptive Scale only significant differences on social skills and leadership were found, with lower score in the ADD/+H group. A crosstab analysis between group code and each rating variable transformed into categorical (0 and 1) variable, cut-off point = 85 percentile, found that the case children's parents qualified as clinically in higher risk the variables attention problems (OR = 24.4; 95% CI = 4.5-130), conduct problems (OR = 9.0; 95% CI = 1.7-46.9) and hyperactivity (OR = 6.8; 95% CI = 1.6-28.5) (p < 0.01). A discriminant analysis selected attention problems as discriminant function (p < 0.0001). Classification capability 84% for each group. CONCLUSION: Our results proved the validity of the BASC-PRS 6-11 questionnaire for the screening diagnosis of ADD/+H children in a Spanish speaking population.

Adult↗
PubMedDate not supplied

[Antiphospholipid syndrome and cardiovascular disease].

Recurrent thrombosis, abortion and thrombocytopenia are the most frequent manifestation of antiphospholipid syndrome, which usually presents antibodies against some anionic phospholipids. A few years ago, this syndrome was considered as a manifestation of systemic lupus erythematosus; nowadays it is classified as an isolated systemic lupus erythematosus; nowadays it is classified as an isolated autoimmune disease. Hypotheses have been proposed to explain the origin of antiphospholipid antibodies, including infectious and autoimmune diseases with high titles of anticardiolipin antibodies. Genetic factors have also been involved. Laboratory tests of choice for the detection of anticardiolipin antibodies are RIA and ELISA tests; there are some structural differences among them depending on the underlying disease. Hypercoagulability and recurrent thrombosis are the main features of this entity; ischemic heart disease is in this context of outmost importance. Despite the lack of any clinically demonstrated association between antiphospholipid syndrome and ischemic heart disease, there are many "in vitro" studies that support this possibility.

Autoantibodies↗
PubMedDate not supplied

[Surgical wound infection in patients undergoing extra-anatomical arterial surgery. A retrospective study].

We present a retrospective review of a series of patients from our Service submitted to surgical extra-anatomical grafts. Correlation between diverse variants and ulterior obliteration by thrombosis or infection of the surgical wounds is analyzed. The series included 133 patients surgically treated between 1986 and 1991. The studied variants were: sex, age, type of graft, the material used, length and type of anesthesia, presentation of hypotension during the surgical intervention, diabetes, platelet recount. Fourteen patients (11%) presented early graft obliteration and 15 (11%) presented an infection of their surgical wound. Only the platelet variant showed statistical differences in patients presenting infection. A high recount of platelets could be a factor risk of infection.

Adult↗
PubMedDate not supplied

[Complete reconstructions without intermediate anastomoses].

Results from 9 complete reconstructions without intermediate anastomosis (8 patients) are presented. In five cases a by-pass from femoral artery to the contralateral popliteal (infra or supra-rotuliar) arterial prosthesis was performed. In other case a by-pass from the aorta artery to the third popliteal section was placed. Other by-pass was performed from the branches of an axillo-bifemoral by-pass to the third popliteal section. The last case was an axillo-bi-popliteal by-pass. All the patients presented a severe ischemia (III and IV Fontaine stadii). Eight millimeter PTFE grafts were used. The distal anastomosis should always be performed in vessels with a low distal resistance.

Aged↗