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Biomedical subjects

J C Prieto

Publications and source records attributed to J C Prieto.

At least 19 recordsLinked to original sources
PubMed2006

Transperitoneal and retroperitoneal laparoscopic heminephrectomy--what approach for which patient?

PURPOSE: We report our experience with laparoscopic heminephrectomy using the transperitoneal and retroperitoneal approaches in 48 pediatric patients. MATERIALS AND METHODS: A total of 48 laparoscopic heminephrectomies were performed in 35 girls and 13 boys 45 days to 17 years old (mean 4.08 years) between September 1998 and March 2005. The procedures consisted of 44 upper pole heminephrectomies with partial or total ureterectomies and 4 lower pole heminephroureterectomies. Surgeries were performed using a transperitoneal approach in 32 patients (67%) and a retroperitoneal approach in 16 (33%). RESULTS: Followup ranged from 0.75 to 7.25 years (mean 3.53). In the retroperitoneal group 2 procedures required conversion, 1 to open heminephrectomy and 1 to a transperitoneal laparoscopic approach. Complications were seen in 5 of 48 patients (10%). Complications in the retroperitoneal group were seen in 2 patients. One patient had a postoperative urinary leak that resolved spontaneously. Another patient had development of a urinoma that was treated conservatively. Complications in the transperitoneal group were seen in 3 patients. One patient required an intraoperative chest tube due to pneumothorax, 1 had recurrent urinary tract infection that required excision of a short ureteral remnant and 1, 6-month-old boy had development of postoperative hypertension. Four of the 5 complications (80%) were seen in patients younger than 1 year. CONCLUSIONS: Transperitoneal and retroperitoneal laparoscopic heminephrectomy can be performed for benign disease in children with minimal morbidity, improved cosmesis and short hospital stay. Complication rate does not depend on the surgical approach, but rather on the age of the patient.

Adolescent↗
PubMed2004

Association of adenylate cyclase with an actin-like protein in the human myometrium.

Regulation of muscle contraction by second messengers such as cAMP and regulation of the adenylate cyclase enzyme by the cytoskeleton have been previously described. However, the physical association of both effector and structural elements is still unknown. In this context, we have co-purified a human myometrial adenylate cyclase with an actin-like protein in a two-step purification protocol. The adenylate cyclase catalytic unit was solubilized with Lubrol-PX, submitted to anionic exchange chromatography and purified about 7-fold. The eluate was applied to a forskolin-agarose column obtaining an adenylate cyclase extract enriched 257-fold (enzymatic activity of 1390 pmol/30 min per mg protein) that co-eluted with a 74.6-kDa protein that possessed the 18-27 amino-acid fragment from the N-terminal region of human actin. Under non-reducing conditions, the apparent molecular weight of this protein decreased to 54 kDa, which has been previously described for arthrin. These results provide the first demonstration of the physical association of human myometrial adenylate cyclase with a cytoskeleton-related protein, supporting the hypothesis that adenylate cyclase is regulated by mechanical stimuli.

Adenylyl Cyclases↗
PubMed2001

Vasoactive intestinal peptide (VIP) stimulates rat prostatic epithelial cell proliferation.

BACKGROUND: Androgens play a major role in supporting normal growth and functional maintenance in the prostate. However, this gland contains an array of neuroendocrine peptides that can play a regulatory role in its physiopathology. Among these peptides, one of the best studied is vasoactive intestinal peptide (VIP), which is abundant in autonomic nerves surrounding both human and rat prostatic acini. This neuropeptide may act through interaction with two types of high-affinity receptors, named VPAC(1) and VPAC(2) receptors. Another regulatory peptide, the pituitary adenylate cyclase-activating peptide (PACAP), interacts with these receptors with the same affinity as VIP, but binds with higher affinity to PAC(1) receptors. Human prostate tumors and rat prostate show a major presence of VPAC(1) receptors, whereas various findings suggest a role for VIP in prostatic development. Here we studied the effects of VIP on the proliferation of rat prostatic epithelial cells in culture. METHODS: We studied the [(3)H]-thymidine uptake by rat prostatic epithelial cells in culture, characterized previously by using biomarkers such as cytokeratin and vimentin. In these cells we tested the effect of VIP and PACAP-27 on two different signaling pathways, the cyclic AMP (cAMP) and the inositol phosphate (IPs). RESULTS: The rat prostatic cells in culture were cytokeratin (5,6,8) and vimentin positive, indicating that the culture was predominantly epithelial. The proliferation curves showed that the cells followed different states of growth: a quiescent, an exponential proliferative, and a steady state. Cyclic AMP production, but not inositol phosphate production, was increased in the presence of VIP and PACAP-27, which suggests the expression of VPAC(1) and/or VPAC(2) receptors primarily. VIP significantly increased prostatic cell proliferation in a bimodal manner, as shown for dibutyryl cyclic AMP (dbcAMP), which suggests that the effect of VIP upon prostatic proliferation is cAMP-dependent. CONCLUSIONS: Here, we demonstrate that VIP increased [(3)H]thymidine uptake by rat prostatic epithelial cells in culture, conceivably by the activation of the adenylate cyclase.

Animals↗
PubMed2001

Neuroendocrine differentiation of the LNCaP prostate cancer cell line maintains the expression and function of VIP and PACAP receptors.

The molecular mechanisms involved in differentiation of prostate cancer cells to a neuroendocrine (NE) cell phenotype are not well understood. Here we used the androgen-dependent human prostate cancer cell line LNCaP to perform a systematic and broad analysis of the expression, pharmacology, and functionality of vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase-activating peptide (PACAP) receptors. Reverse transcription polymerase chain reaction experiments, together with pharmacological approaches with a set of specific agonists and antagonists, demonstrated the presence of the three VIP/PACAP receptor subtypes (PAC1, VPAC1, and VPAC2 with a major role for VPAC1, acting through adenylate cyclase (AC) stimulation. An essentially similar pattern was observed by NE differentiated cells (4 days after serum deprivation) in spite of the important morphological changes observed. However, the expression of the prostate-specific antigen (PSA) decreased in NE cells (and increased again by dihydrotestosterone, DHT, treatment). The present demonstration of the induction of NE transdifferentiation in LNCaP cells by increasing concentrations of VIP adds value to previous observations on the role of cAMP in this process, an interesting topic in the comprehension of the molecular changes that are involved in the progression of prostate cancer to androgen independence.

Adenylyl Cyclases↗
PubMed2001

Effects of the luteinising hormone-releasing hormone (LH-RH) agonist leuprolide on adenylyl cyclase regulation through G-protein coupled receptors in rat ventral prostate.

Luteinising hormone-releasing hormone (LH-RH) agonists are widely used for the therapy of advanced prostate cancer through the suppression of testosterone secretion. Furthermore, recent studies indicate the existence of prostate LH-RH receptors coupled to signalling pathways resulting in direct antiproliferative effects. In order to shed light on the mechanisms through which these compounds inhibit prostate cell growth, we investigated the effects of leuprolide (a LH-RH agonist) treatment of rats compared with the effects of surgical castration on the behaviour of G-protein coupled receptors acting through adenylyl cyclase in the ventral prostate. Important decreases of both plasma testosterone levels and ventral prostate weight were observed 5 weeks after subcutaneous (s.c.) injection of a leuprolide-depot preparation (1.5 mg/kg body weight (b.w.)) or 5 days after bilateral gonadectomy. However, leuprolide treatment increased the number of vasoactive intestinal peptide (VIP) receptors and the ability of this neuropeptide to stimulate adenylyl cyclase activity in prostate membranes, whereas surgical castration decreased both parameters. Moreover, leuprolide resulted in significant increases of prostate alpha(s) and alpha(i1-3) (but not alpha(i1) and beta) G-protein levels, while the four G-protein subunits were overexpressed after gonadectomy. The estimation of alpha(s) and alpha(i) activity by experiments with Gpp[NH]p and forskolin indicated a potentiation of the two arms of adenylyl cyclase regulation in leuprolide-treated rats. Present observations suggest that leuprolide treatment leads to an antimitogenic response by acting mainly through the activation of Gi proteins negatively coupled to adenylyl cyclase.

Adenylyl Cyclases↗
PubMed2001

[Changes in the patterns of drug prescription for acute myocardial infarct. Comparison of 2 periods].

BACKGROUND: Pharmacotherapy of Chilean patients with acute myocardial infarction has been recorded in 37 hospitals since 1993. AIM: To compare pharmacotherapy for acute myocardial infarction in the period 1993 to 1995 with the period 1997-1998. PATIENTS AND METHODS: Drug prescription during hospital stay was recorded in 2957 patients admitted to Chilean hospitals with an acute myocardial infarction in the period 1993-1995 and compared with that of 1981 subjects admitted in the period 1997-1998. RESULTS: When compared with the former period, in the lapse 1997-1998 there was an increase in the frequency of prescription of aspirin (93 and 96.1% respectively) beta blockers (37 and 55.2% respectively) and angiotensin converting enzyme inhibitors (32 and 53%). The prescription of thrombolytic therapy did not change (33 and 33.7% respectively). There was a reduction in the prescription of calcium antagonists and antiarrhythmic drugs. CONCLUSIONS: During the period 1997-1998, the prescription of drugs with a potential to reduce the mortality of acute myocardial infarction, increased. The diffusion of guidelines for the management of this disease may have influenced this change.

Adrenergic beta-Antagonists↗
PubMed2001

Low expression of Galpha protein subunits in human prostate cancer.

PURPOSE: Because of increasing interest in G protein regulation of cell growth, differentiation and oncogenesis, we studied the functionality and expression of different G protein subunits in human prostate adenocarcinoma. MATERIALS AND METHODS: Surgical prostate specimens from control patients with bladder cancer and patients with prostate cancer were used. The functionality of alphas and alphai G protein subunits was evaluated by studying somatostatin or guanyl-5'-yl-imidotriphosphate regulation of forskolin stimulated adenylyl cyclase activity. The expression of alphas, alphai and beta subunits was studied by reverse transcriptase-polymerase chain reaction and immunoblot analysis. RESULTS: Adenylyl cyclase sensitivity to somatostatin inhibition decreased in prostate cancer. Low guanyl-5'-yl-imidotriphosphate doses inhibited forskolin stimulated adenylyl cyclase, whereas the opposite was true at high concentrations, evidencing the functionality of alphai and alphas, respectively, in normal and cancer tissue samples. Reverse transcriptase-polymerase chain reaction revealed RNA encoding for alphas and alphai1,2,3 subclasses in normal and pathological conditions. However, immunoblot analysis showed that the level of beta subunits was maintained, whereas that of alphas and alphai subunits decreased 30% to 40% after neoplastic transformation. The levels of alphas and alphai1,2 subunits correlated inversely with serum prostate specific antigen in patients with prostate cancer. CONCLUSIONS: The functionality and expression of G protein subunits are selectively modified in human prostate adenocarcinoma. Low alphas and alphai levels in prostate cancer suggest an important regulatory role of G proteins for cell proliferation and neoplastic transformation in the human prostate and they may have prognostic value.

Adenocarcinoma↗
PubMed2001

[Cardiovascular risk factors in middle-age women with acute coronary syndromes].

BACKGROUND: In Chile, 40% of deaths due to acute myocardial infarction occur in women. AIM: To assess the presence of cardiovascular risk factors in women with acute coronary syndromes. PATIENTS AND METHODS: Thirty four women aged 46 to 55 years old, admitted to the hospital due to an acute coronary syndrome and 102 age matched healthy women were studied. A clinical history was obtained, blood pressure and fasting serum lipids were measured. RESULTS: A history of high blood pressure was present in 65 and 16% of patients and healthy controls respectively. Seventy seven percent of patients and 36% of controls smoked, 76% of patients and 48% of controls were postmenopausal, 21% of patients an 5% of controls were diabetic. In patients and controls respectively serum total cholesterol was 230.1 +/- 36.2 and 211.2 +/- 34.8 mg/dl, serum triacylglycerol was 213.4 +/- 109.4 and 143.2 +/- 76.9 mg/dl and serum HDL cholesterol was 44.1 +/- 10.8 and 49.8 +/- 13.3 mg/dl (p < 0.001 or less). In univariate analysis, the risk of acute coronary syndrome increased with high blood pressure (OR: 9.3, CI: 2.5-18.6), menopause (OR: 8.3, CI: 2.2-31:5), smoking (OR: 6.9, CI: 2.5-18.6), diabetes mellitus (OR: 5.0, CI: 1.4-17.5), a high total cholesterol/HDL cholesterol ratio (OR: 6.6, CI: 1.8-12.5) and hypertriglyceridemia (OR: 3.6, CI: 1.5-8.5). Logistic regression analysis showed that hypertension and menopause had the higher predictive values for acute coronary syndrome. CONCLUSIONS: In this group of women with acute coronary syndromes, the main coronary risk factors were high blood pressure and menopause.

Analysis of Variance↗
PubMed2001

[Safety profile of statins].

HMG-CoA reductase inhibitors (statins) are the treatment of choice for patients with hypercholesterolaemia. Several large-scale clinical trials have examined the efficacy and tolerability of statins, providing a wealth of information on their safety and adverse effect profile. Adverse hepatic effect is reflected as asymptomatic elevations in serum levels of aminotransaminases. Myopathy, occasionally leading to myoglobulinuria secondary to rhabdomyolysis, is a rare and potentially fatal complication. Cerivastatin, the last statin approved for use in humans, was voluntarily withdrawn from the market by Bayer, because fatal rhabdomyolysis was most frequently reported with cerivastatin than for other approved statins. The concomitant use of statins with drugs that inhibit CYP3A4 (cyclosporin, erythromycin, clarithromycin, itraconazole, and ketoconazole), may result in increased plasma concentrations of HMG-CoA reductase inhibitors leading occasionally to myotoxicity. Fibric acid derivatives can produce myotoxicity, and the association of both types of drugs increases the risk of this adverse event. The reason for the greater association of rhabdomyolysis with cerivastatin than with other statins is unknown. The efficiency of post marketing drug surveillance programs in different countries, was the clue for the awareness of this problem.

Anticholesteremic Agents↗
PubMed2000

Multiple regulation of adenylyl cyclase activity by G-protein coupled receptors in human foetal lung fibroblasts.

The pharmacological profile of adenylyl cyclase activity was analysed in WI-38 human foetal lung fibroblasts. Among various agents that act through G-protein coupled receptors, only the beta-adrenergic agonist isoproterenol stimulated and the tetradecapeptide somatostatin (SRIF, sst) inhibited the enzyme activity. The use of the reverse transcription-polymerase chain reaction (RT-PCR) methodology with appropriate cDNAs allowed us to identify the expression of four subtypes of SRIF transmembrane receptors (sst1-4 but not sst5 receptors) in this cell line. By RT-PCR and immunochemistry techniques, we also demonstrated the expression of stimulatory (alpha(s)) and inhibitory (alpha(i1), alpha(i2) and alpha(i3)) G-protein subunits. The known role of the adenylyl cyclase system in cell proliferation and differentiation mechanisms together with the present analysis of the corresponding regulatory network in fibroblasts of human foetal lung add knowledge on the cell line WI-38 that is widely used as a model system in studying cell growth. The importance of this cell class in normal and abnormal lung function and development reinforces the significance of these results.

Adenylyl Cyclases↗
PubMed2000

Effects of Pygeum africanum extract (Tadenan) on vasoactive intestinal peptide receptors, G proteins, and adenylyl cyclase in rat ventral prostate.

BACKGROUND: Tadenan (a Pygeum africanum extract) is a drug used in the treatment of benign prostatic hyperplasia. Its effects on prostate fibroblast proliferation and bladder function after partial outlet obstruction have been demonstrated in various pharmacological studies. However, its effects at the molecular level are poorly documented. METHODS: Tadenan was dissolved in peanut oil. Rats were orally given two daily doses of the drug (1 or 10 mg/kg b.w.) for 4 days. Vasoactive intestinal peptide (VIP) binding, adenylyl cyclase stimulation, and expression of G-protein subunits were studied in rat prostatic membranes by established procedures. RESULTS: Tadenan treatment of castrated/testosterone-replaced rats was performed in order to interfere with prostatic cell proliferation. This experimental approach resulted in increases of: 1) VIP effect on adenylyl cyclase stimulation through alpha(s) G-subunit; 2) alpha(i) activation by low Gpp[NH]p doses (in the presence of forskolin); and 3) alpha(s), alpha(i1/2), and alpha(i3/0) levels. However, there were no modifications in membranes from quiescent, nonproliferating prostates (untreated rats). CONCLUSIONS: The observed regulatory role of Tadenan on various prostatic components of the adenylyl cyclase system, together with previous findings on protein kinase C-mediated signal transduction, open a complex array of possibilities of direct actions of this phytotherapeutic agent in the prostate.

Adenylyl Cyclases↗
PubMed2000

Expression of vasoactive intestinal peptide (VIP) receptors in human uterus.

We show the existence of functional vasoactive intestinal peptide (VIP) receptors in normal human female genital tract (endometrium, myometrium, ovary and Fallopian tube) as well as in leiomyoma (a frequent uterine pathology). The correlation between VIP binding and stimulation of adenylyl cyclase activity for all studied tissues was linear (r = 0.86) suggesting the expression of VIP receptors throughout the human female genital tract. Immunodetection of VIP receptor subtypes gave different molecular weights for VPAC(1) (47 kDa primarily) and VPAC(2) (65 kDa), which may be due to different glycosylation extents. In conclusion, this study demonstrates the expression of both subtypes of VIP receptors and their functionality in human female genital tract, suggesting that this neuropeptide could play an important physiological and pathophysiological role at this level.

Adenylyl Cyclases↗
PubMed2000

Immunohistochemical localization and distribution of VIP/PACAP receptors in human lung.

VIP and PACAP are distributed in nerve fibers throughout the respiratory tract acting as potent bronchodilators and secretory agents. By using RT-PCR and immunoblotting techniques, we have previously shown the expression of common VIP/PACAP (VPAC(1) and VPAC(2)) and specific PACAP (PAC(1)) receptors in human lung. Here we extend our aims to investigate by immunohistochemistry their localization and distribution at this level. A clear immunopositive reaction was obtained in human lung sections by using either anti-VPAC(1) or -VPAC(2) receptor antibodies but not with anti-PAC(1) receptor antibody. However, PAC(1) receptor (and VPAC(1) and VPAC(2) receptors) could be identified in lung membranes by immunoblotting which supports that the PAC(1) receptor is expressed at a low density. Both VPAC(1) and VPAC(2) receptors showed similar immunohistochemical patterns appearing in smooth muscle cells in the wall of blood vessels and in white blood cells (mainly in areas with inflammatory responses). The results agree with previous evidence on the importance of both peptides in the immune system and support their anti-inflammatory and protective roles in lung.

Adult↗
PubMed2000

Effect of flutamide-induced androgen-receptor blockade on adenylate cyclase activation through G-protein coupled receptors in rat prostate.

The effect of the antiandrogen flutamide on the prostatic vasoactive intestinal peptide (VIP) receptor/effector system was studied in rats. Rats were s.c. injected with a daily dose of flutamide (15 mg/kg B.W.) or vehicle for 14 days. Drug treatment resulted in histological evidence of gland involution and increased plasma membrane fluidity as estimated by fluorescence spectroscopy. The number of VIP receptors and the stimulatory effect of VIP on adenylate cyclase activity in prostatic membranes decreased in flutamide-treated rats. However, the pattern of forskolin stimulation of the enzyme activity was not modified by this drug. Androgen-receptor blockade by flutamide also decreased the prostatic levels of alpha(s,) alpha(i1/2), and alpha(i3/0) G-protein subunits, as estimated by an immunological procedure. Whereas apoptotic DNA fragmentation was evidenced in prostate from 3-day castrated animals, a heterogeneous electrophoretic pattern was observed after flutamide treatment. Thus, androgen-receptor blockade by flutamide results in an important impairment of the components of the VIP receptor/effector system in rat prostate as well as in a modification of their coupling extent, which is presumably due to differences observed in plasma membrane fluidity. These results represent a crosstalk in the prostate between two mechanisms of signal transduction involved in cell proliferation.

Adenylyl Cyclases↗
PubMed2000

Impairment of adenylate cyclase activity and G-proteins in human uterine leiomyoma.

The mechanisms responsible for the growth of uterine leiomyoma (a frequent cause of infertility in women) are largely unknown. Some data supports that cAMP plays a role in the growth of uterine cells but there are no reports on the status of the cAMP producing system in this human benign neoplasia. In this study, biopsies from leiomyoma and the adjacent myometrium were taken from menstruating women subjected to total hysterectomy for leiomyoma. Adenylate cyclase activity was determined by a protein-binding method, and the expression of alpha(s), alphai1/2, alphai3 and alphai0) G-protein subunits was analysed by immunoblot. The leiomyoma samples exhibited a decreased expression of as and ai1/2 with respect to the adjacent myometrial tissue. No differences were observed in alphai3 and alphaio protein expression. The basal adenylate cyclase activity as well as the efficacy (as assessed by the maximal stimulation levels) of either forskolin or, to a lesser extent, Gpp[NH]p on stimulation the enzyme activity was significantly lower in leiomyoma than in myometrium, whereas the potency (as assessed by the ED50 values) of these two agents did not vary. Present data indicate that the human leiomyoma is associated with low levels of cAMP. It is conceivable that the loss of sensitivity of adenylate cyclase to endogenous regulatory molecules could be related to the pathogenesis of human leiomyomas given that cAMP inhibits the MAP-kinase cascade in uterine tissues.

Adenylyl Cyclase Inhibitors↗
PubMed2000

Isobolographic analysis of the interaction between fenoldopam and levodopa on arterial blood pressure of the rat.

Fenoldopam (FD) and levodopa (LD) injected intravenously in rats in a noncumulative schedule induced dose-dependent reductions in mean arterial blood pressure. The doses that induced a 50% reduction in the initial control mean arterial pressure (referred as ED50) were calculated by linear regression analysis of the corresponding parallel dose-response curves and were 0.88 and 0.068 mg/kg, respectively. The interaction between the effects of FD and LD on pressure reduction was evaluated by simultaneous administration of different fixed ratios of FD and LD (16:1) and obtaining a dose-response curve. An isobolographic analysis was then performed, which showed that the experimental point for the effect of the simultaneous administration of FD and LD was significantly different from the theoretically calculated additive point, denoting supradditivity. It was concluded that the effect of the combination of FD and LD on mean blood pressure reduction was synergic and was probably due to an activation of D1 vascular receptors by both drugs, in conjunction with an activation of beta2 adrenoceptors by LD and a blocking action of FD on postsynaptic alpha1-adrenoceptors.

Animals↗