Receptors involved in dexketoprofen analgesia in murine visceral pain

Various animal models, especially rodents, are used to study pain, due to the difficulty of studying it in humans. Many drugs that produce analgesia have been studied and there is evidence among which NSAIDs deserve to be highlighted. Dexketoprofen (DEX) provides a broad antinociceptive profile in different types of pain; therefore, this study was designed to evaluate the profile of antinociceptive potency in mice. Analgesic activity was evaluated using the acetic acid abdominal constriction test (writhing test), a chemical model of visceral pain. Dose-response curves for i.p. DEX administration (1, 3, 10, 30 and 100 mg/kg), using at least six mice in each of at least five doses, was obtained before and 30 min after pre-treatment with different pharmacological agents. Pretreatment of the mice with opioid receptor antagonists was not effective; however, the serotonin receptor antagonist and nitric oxide synthase inhibitor produce a significant increase in DEX-induced antinociception. The data from the present study shows that DEX produces antinociception in the chemical twisting test of mice, which is explained with difficulty by the simple inhibition of COX. This effect appears to be mediated by other mechanisms in which the contribution of the NO and 5-HT pathways has an important effect on DEXinduced antinociception.

Utility of retrograde ureterocelogram in management of complex ureterocele

INTRODUCTION

Symptomatic pediatric ureterocele has diverse manifestations, making evidence-based management impractical. Thus, detailed visualization of ureterocele anatomy prior to first surgical incision is invaluable. Retrograde ureterocelogram (RUC) is a simple, underutilized radiologic technique that can be performed during cystoscopy. This study sought to determine whether RUC changes surgical management by more accurately depicting the complex ureteral and ureterocele anatomy, compared with renal ultrasound (US) and voiding cystourethrography (VCUG).

METHODS

Patients who underwent surgical management of ureterocele from 2003 to 2015 were identified; those who received concomitant fluoroscopic RUC were selected for the case series. Data collected included: demographics, pre-operative evaluation, surgical interventions, and outcomes. The RUC images were individually examined, and the anatomic impression compared with previous renal US and VCUG. Novel RUC findings not previously appreciated by the pre-operative evaluation were noted. The RUC was performed by cystoscopically inserting a needle into the ureterocele and injecting contrast retrograde. If indicated, simultaneous PIC (Positioning the Instillation of Contrast) cystography was performed.

RESULTS

Of the 43 patients that underwent surgery for suspected ureterocele, 28 underwent cystoscopy + RUC (10 M: 18 F) at a median age of 4.6 months and median follow-up of 37.0 months. All patients had prior US, 25 had prior VCUG, and 20 had prior radionuclide studies. Ureteroceles were either duplex system (n = 21) or single system (n = 7); 17 were ectopic into the bladder neck or urethra; seven were intravesical; and four were pseudoureteroceles. Fourteen patients underwent concomitant transurethral incision of the ureterocele (TUIU); two were deferred for surgery; and 11 received concomitant definitive surgery (e.g., nephrectomy). The RUC illuminated novel aspects of the anatomy in 20 of the 28 patients. No adverse events occurred. Notably, in nine of the 28 children, significant observations from RUC prompted change to the pre-operative surgical plan.

DISCUSSION

Retrograde ureterocelogram clearly revealed ureterocele ectopy, pseudoureterocele, ureterocele disproportion, and unsuspected duplex systems, making it a useful adjunct to standard US and VCUG studies. Retrograde ureterocelogram can also be used to fluoroscopically verify decompression of the ureterocele post incision, document severity of ureteral dilation, and teach residents about the great damage generated by ureterocele variations. Limitations of RUC included increasing radiation dose and overall cost. The study design was limited by its small size, retrospective approach, selection bias, and availability of RUC images.

CONCLUSIONS

While not indicated in routine ureterocele management, intraoperative RUC further defined ureterocele anatomy in nearly all cases and yielded changes to the original surgical plan frequently enough to merit greater use in complex patients.

[Hip fracture, antiplatelet drugs treatment and postoperative complications]

OBJECTIVES

To assess the incidence of postoperative complications, blood transfusions and survival at one month, in the old patients operated for hip fracture undergoing chronic treatment with antiplatelet drugs.

MATERIAL AND METHODS

Two hundred twenty three patients operated for hip fracture were studied retrospectively, separated into 3 groups: patients who received acetylsalicylic acid (group I), patients who were given 100mg/day of acetylsalicylic acid or 300mg/day of triflusal (group II) and patients receiving>100mg/day of acetylsalicylic acid, or>300mg/day of triflusal or thienopyridines (group III). Surgery was delayed for 4 days in patients in group III. Demographic, biological, clinical and treatment characteristics, postoperative complications and survival at one month were recorded.

RESULTS

Patients in group III were older and sustain worse general health status. Patients with a higher transfusion requirement were those of group II (73.8%) (P=0.192), who also showed a higher percentage of anaemia on admission. Severe cardiovascular complications were experienced by 5.4% of group III patients, 4.8% of group II patients and 2.1% of group I patients. Patients from group III presented a significant amount of respiratory complications (P=0.007).

CONCLUSIONS

Our results suggest that delaying surgery for 4 days in patients treated with clopidogrel can be associated to an increase in postoperative respiratory complications and severe adverse cardiovascular events, without increasing the tranfusional index, hospital stay, mortality, and without complications related to neuraxial anaesthesia.

Synergism between COX-3 inhibitors in two animal models of pain

OBJECTIVE AND DESIGN

The antinociception induced by the intraperitoneal coadministration in mice of combinations of metamizol and paracetamol was evaluated in the tail flick test and orofacial formalin test.

METHODS

The antinociception of each drugs alone and the interaction of the combinations was evaluated by isobolographic analysis in the tail-flick and in the formalin orofacial assay of mice.

RESULTS

Mice pretreated with the drugs demonstrated that the antinociception of metamizol and paracetamol is dose-dependent. The potency range on the antinocifensive responses for metamizol or paracetamol was as follows: orofacial (Phase II) > orofacial (Phase I) > tail flick. In addition, the coadministration of metamizol with paracetamol induced a strong synergistic antinociception in the algesiometer assays. Both drugs showed effectiveness in inflammatory pain.

CONCLUSION

These actions can be related to the differential selectivity of the drugs for inhibition of COX isoforms and also to the several additional antinociception mechanisms and pathways initiated by the analgesic drugs on pain transmission. Since the efficacy of the combination of metamizol with paracetamol has been demonstrated in the present study, this association could have a potential beneficial effect on the pharmacological treatment of clinical pain.

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.

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.

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.

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.

[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.

[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.

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.

[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.

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.

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.

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.

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.

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.

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.

Identification of functional somatostatin receptors and G-proteins in a new line of human foetal lung fibroblasts

A new line (FP) of human foetal lung fibroblasts was analysed for the expression of functional, G-protein coupled somatostatin receptors (SSTR). By means of RT-PCR, we identified the expression of SSTR1, SSTR2, SSTR3 and SSTR4, but not SSTR5, subtypes. The same technical approach evidenced the expression of stimulatory (alphas) and inhibitory (alphai1, alphai2 and alphai3) G-protein subunits. The functionality of SSTR was established from the observation of a dose-dependent inhibitory role of SST upon isoproterenol-stimulated adenylyl cyclase activity, an effect that involves G-protein action. Moreover, the functionality of G-proteins was assessed by means of experiments with forskolin and a nonhydrolysable GTP analogue that showed either Gi or Gs activation in the regulation of adenylyl cyclase. Present results represent a first pharmacological characterization of this new line of human foetal lung fibroblasts. The selective presence of some SSTR subtypes and G-protein subunits in addition to the regulatory network of the adenylyl cyclase pathway are features of recognized involvement in cell growth mechanisms. It is of interest for a cell class widely used to study this topic but also important in lung physiology and pathophysiology.

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.

Modulation of guanosine triphosphatase activity of G proteins by arachidonic acid in rat Leydig cell membranes

Previous results from our group have indicated that arachidonic acid decrease cAMP production through a modification of heterotrimeric G proteins. In the present study, we have characterized the high affinity GTPase activity present in Leydig cell membranes and its regulation by fatty acids. The high-affinity GTPase activity, measured as [gamma32P] GTP hydrolysis rate, was both time and protein concentration dependent. Arachidonic acid elicited a dose-dependent inhibition of enzyme activity with an IC50 = 26.7+/-1.1 microM. The existence of only two double bonds in linoleic acid is reflected by a decrease in its inhibitory activity (IC50 = 34+/-2.3 microM). Saturated fatty acids showed no effect at this level. The kinetic analysis as interpreted by Lineweaver-Burk plots, indicated that 50 microM arachidonic acid had no effect on the apparent affinity for GTP, but resulted in a 40% decreases in the maximal velocity of the reaction. Arachidonic acid modulation of GTPase activity was not attenuated by blocking eicosanoid metabolism with inhibitors of 5'-lipoxygenase, cyclooxygenase, or epoxygenase P-450. The addition of arachidonic acid to pertussis toxin-treated membranes had no effect on the enzyme activity, indicating that arachidonic acid does not modify the GTPase activity present in Galphas protein. However, ADP-ribosylation with cholera toxin followed by arachidonic acid treatment led to a further 40% inhibition when compared with cholera toxin treatment alone. These results allowed us to postulate that arachidonic acid inhibits the GTPase activity of Gi protein family. To further analyze the mechanism of arachidonic acid inhibition of GTPase activity, the effect of arachidonic acid on the [35S]GTPgammaS binding was studied. No effect of this fatty acid on GTP binding was found. Combining our previous results with those found here, we can conclude that arachidonic acid maintains Gi proteins in their active state, which in turn inhibit adenylate cyclase and results in decrease cAMP levels.

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.

Identification and functional properties of the pituitary adenylate cyclase activating peptide (PAC1) receptor in human benign hyperplastic prostate

Pituitary adenylate cyclase activating peptide (PACAP) is a novel neuropeptide with regulatory and trophic functions that is related to vasoactive intestinal peptide (VIP). Here we investigate the expression of specific PACAP receptors (PAC1) and common VIP/PACAP receptors (VPAC1 and VPAC2) in the human hyperplastic prostate by immunological methods. The PAC1 receptor corresponded to a 60-KDa protein whereas the already known VPAC1 and VPAC2 receptors possessed molecular masses of 58 and 68 KDa, respectively. The heterogeneity of VIP/PACAP receptors in this tissue was confirmed by radioligand binding studies using [125I]PACAP-27 by means of stoichiometric and pharmacological experiments. At least two classes of PACAP binding sites showing different affinities could be resolved, with Kd values of 0.81 and 51.4 nM, respectively. The order of potency in displacing [125I]PACAP-27 binding was PACAP-27 approximately equal to PACAP-38 > VIP. PACAP-27 and VIP stimulated similarly adenylate cyclase activity, presumably through common VIP/PACAP receptors. The PAC1 receptor was not coupled to activation of either adenylate cyclase, nitric oxide synthase, or phospholipase C. It appears to be a novel subtype of PAC1 receptor because PACAP-27 (but not PACAP-38 or VIP) led to increased phosphoinositide synthesis, an interesting feature because phosphoinositides are involved via receptor mechanisms in the regulation of cell proliferation.

Bedside markers of coronary artery patency and short-term prognosis of patients with acute myocardial infarction and thrombolysis

BACKGROUND

In this study we have evaluated the prognostic power of noninvasive markers of coronary artery reperfusion in patients with acute myocardial infarction who were treated with intravenous streptokinase.

METHODS

In 967 consecutive patients with acute myocardial infarction who were treated within 6 hours of symptoms, we analyzed the prognostic power of resolution of chest pain and ST-segment elevation >50% at 90 minutes, abrupt creatine kinase rise before 12 hours, and T-wave inversion in infarct-related electrocardiographic leads within the first 24 hours after thrombolysis.

RESULTS

Global in-hospital mortality rate was 12.0%. Each reperfusion marker was associated with improved outcome. Multivariate logistic regression analysis showed that 3 of the 4 markers of coronary artery reperfusion were significantly and independently associated to low in-hospital mortality rate. The presence of early T-wave inversion was associated with the lowest in-hospital mortality rate (odds ratio 0.25, confidence interval 0. 10-0.56). When all markers of coronary artery reperfusion were included in the regression model, T-wave inversion (odds ratio 0.29, confidence interval 0.11-0.68) and abrupt creatine kinase rise (odds ratio 0.36, confidence interval 0.16-0.77) continued to be significantly associated with better outcome.

CONCLUSION

A systemic analysis of noninvasive markers of coronary artery reperfusion can provide the clinician with an excellent tool to predict clinical outcomes when treating myocardial infarction.

[Acute myocardial infarction in Chilean hospitals. Final results of the GEMI study]

BACKGROUND

Acute myocardial infarction is the leading cause of death in Chile.

AIM

To report the main features, hospital evolution, complications and pharmacological treatment of patients admitted to Chilean hospitals with the diagnosis of acute myocardial infarction.

PATIENTS AND METHODS

Between 1993 and 1995, the GEMI group registered 2,957 patients admitted to 37 hospitals with the diagnosis of acute myocardial infarction.

RESULTS

Mean age of patients was 62 +/- 2 years old and 74% were male. Forty six percent had a history of hypertension and 40% were smokers. During the first five days of admission, 93% of patients received aspirin, 95% received intravenous nitrates, 59% intravenous heparin, 56% oral nitrates, 37% beta blockers, 32% angiotensin-converting enzyme inhibitors, 33% thrombolytic agents, 29% antiarrhythmics and 23% calcium antagonists. Coronary angiograms were performed in 28% of patients, angioplasty in 9% and 8% were subjected to a coronary bypass. Global hospital mortality was 13.4% (19.5% in women and 11.1% in men, p < 0.001).

CONCLUSIONS

This work gives a picture of myocardial infarction in Chilean hospitals. Pharmacological treatment is similar to that used abroad, but certainly it can be optimized.

Expression, pharmacological, and functional evidence for PACAP/VIP receptors in human lung

Pituitary adenylate cyclase-activating peptide (PACAP) type 1 (PAC(1)) and common PACAP/vasoactive intestinal peptide (VIP) type 1 and 2 (VPAC(1) and VPAC(2), respectively) receptors were detected in the human lung by RT-PCR. The proteins were identified by immunoblotting at 72, 67, and 68 kDa, respectively. One class of PACAP receptors was defined from (125)I-labeled PACAP-27 binding experiments (dissociation constant = 5.2 nM; maximum binding capacity = 5.2 pmol/mg protein) with a specificity: PACAP-27 approximately VIP > helodermin approximately peptide histidine-methionine (PHM) >> secretin. Two classes of VIP receptors were established with (125)I-VIP (dissociation constants of 5.4 and 197 nM) with a specificity: VIP approximately helodermin approximately PACAP-27 >> PHM >> secretin. PACAP-27 and VIP were equipotent on adenylyl cyclase stimulation (EC(50) = 1.6 nM), whereas other peptides showed lower potency (helodermin > PHM >> secretin). PACAP/VIP antagonists supported that PACAP-27 acts in the human lung through either specific receptors or common PACAP/VIP receptors. The present results are the first demonstration of the presence of PAC(1) receptors and extend our knowledge of common PACAP/VIP receptors in the human lung.

Effects of chronic ethanol ingestion on the vasoactive intestinal peptide receptor-effector system from rat seminal vesicle membranes

We studied the modifications of the vasoactive intestinal peptide (VIP) receptor/effector system from the rat seminal vesicle after chronic ethanol ingestion. Ethanol treatment resulted in a decreased height of the secretory epithelium of seminal vesicle as well as in a weight loss of this gland. These morphological changes were accompanied by an increase of immunoreactive vasoactive intestinal peptide (VIP) levels and a decrease of the stimulatory effect of VIP adenylate cyclase activity in the seminal vesicle. The loss of sensitivity of the enzyme to VIP was conceivably related to a decrease in the affinity of VIP receptors rather than to a decrease in their number. The changes in the affinity of the VIP receptors were accompanied with a lower sensitivity of VIP binding to GTP, which suggest an uncoupling between the receptor and the transductor molecules. However, chronic exposure to ethanol did not modify either the levels of G-protein subunits (alpha(s) and alpha(i1/2)) or the GTPase activity from seminal vesicle membranes. Moreover, ethanol feeding did not affect adenylate cyclase activity stimulated by forskolin or by Gpp(NH)p. Thus, ethanol-induced changes in the sensitivity of adenylate cyclase to VIP appear to be attributed to an alteration in the VIP-receptor/G-protein interphase rather than in the G-protein/adenylate cyclase connection.

The effect of fenoldopam on the blood pressure of the rat

1. Fenoldopam mesylate, a benzazepine derivative, is a D1 receptor agonist that lowers blood pressure through vasodilation of renal, mesenteric, coronary and cerebral vascular beds. 2. Experiments were performed in rats, and mean carotid blood pressure and heart rate were registered. Two series of experiments were performed: (1) fenoldopam as control group and (2) fenoldopam after pretreatment with one of the following drugs: the D1 antagonist SCH 23390, the D2 antagonist sulpiride, the selective beta1-adrenergic antagonist atenolol, the selective beta2-adrenergic antagonist ICI 118.551, the nonselective beta-adrenergic antagonist propranolol and the neurotoxin that destroys catecholaminergic nerve terminals 6-hydroxydopamine (6-OH-DA). 3. Fenoldopam produced a dose-dependent hypotensive effect that was not modified by pretreatment of the rat with atenolol or propranolol; however, ICI 118.551 produced a significant reduction of the hypotensive response induced by fenoldopam. 4. Pretreatment of the animals with SCH 23390 produced a significant dose-related reversal of the rat blood pressure reduction induced by low doses of fenoldopam. Sulpiride produced a result similar to that induced by pretreatment with SCH 23390. 5. The pretreatment of the animals with 6-OH-DA surprisingly attenuated the response induced by fenoldopam and produced only a significant reversal of the reduction of mean blood pressure induced with the lower dose of fenoldopam. 6. The findings obtained in the present work do not provide further evidence of direct participation of beta2-adrenergic receptors on the mechanism of action of fenoldopam. Its action seems to be mainly due to activation of D1 cardiovascular receptors.

Cyclosporin A induces apoptosis in rat hepatocytes in culture

Cyclosporin A (CsA) at concentrations up to 1 microM induced apoptosis in a dose-dependent manner in cultured rat hepatocytes for 48 h in the presence of insulin and epidermal growth factor (EGF). The effect of CsA was evidenced by the DNA fragmentation pattern constituted by fragments of multiples of 180-200 base pairs, which is a characteristic of programmed cell death. The metabolic activity did not change significantly in the presence of 0.1 microM CsA and diminished to 49% of control in the presence of 1 microM CsA. Changes in the metabolic activity were correlated with a decrease in both [methyl-3H]thymidine uptake and DNA content, which reflects a decrease in the cell number. The treatment of cells with CsA (1 microM) decreased the metabolic activity/DNA content ratio by 24% with respect to dimethyl sulphoxide (DMSO) control, which also suggests, under these conditions, that the necrosis achieved is at most only 24%. In addition, the changes observed (apoptotic process, arrest of the cell cycle and apparition of a necrotic process) were correlated with an increase in the high-affinity guanosine triphosphatase (GTPase) enzymes.

G-protein regulation of adenylate cyclase activity in rat prostatic membranes after chronic ethanol ingestion

BACKGROUND

The possibility that long-term ethanol ingestion might alter either vasoactive intestinal peptide (VIP) content, VIP binding to membrane receptors, G-protein levels or adenylate cyclase activity in rat prostate was tested, as ethanol produces serious alterations in the hypothalamic-pituitary-gonadal axis and several modifications on different elements on signal transduction pathways in other systems.

METHODS

Prostatic membranes from control and ethanol-treated (for 4 weeks) rats were used to study adenylate cyclase stimulation as well as for the immunodetection of stimulatory (alpha(s)) and inhibitory (alpha(i)1-2) G-protein subunits. Studies on VIP binding and cross-linking to receptors were performed using [125I]VIP. Prostatic VIP content was estimated by radioimmunoassay. GTPase activity was quantified by measuring the amount of 32Pi released from [gamma-32P]GTP.

RESULTS

Chronic ethanol ingestion resulted in an increased presence of VIP in the rat prostate without any change on the VIP receptor/effector system in this gland. By contrast, the basal adenylate cyclase activity as well as the dose-dependent stimulation of this enzyme by either the nonhydrolyzable GTP analogue Gpp(NH)p or the beta-adrenergic agonist isoproterenol were enhanced in prostatic membranes after ethanol intake. Moreover, an increase in the content of G-protein subunits (alpha(S) and alpha(i)1-2) was observed without any change in GTPase activity in this condition. These modifications were accompanied by a significant decrease in rat prostate weight and, consequently, the height of the secretory epithelium in this gland.

CONCLUSIONS

Considering the role of VIP in the mechanisms of secretion and cell proliferation in the prostate, the observed increases in the prostatic content of VIP and G-protein subunits make conceivable that VIP and cAMP signal transduction could be involved in the atrophy of the rat prostate and in the alterations in the composition of seminal fluid that appear in the alcoholic syndrome.

5-hydroxytryptamine1A receptor-mediated effects on adenylate cyclase and nitric oxide synthase activities in rat ventral prostate

The rat ventral prostate possesses specific 5-hydroxytryptamine (5-HT1A) receptors coupled to adenylate cyclase. In vivo treatment of rats or in vitro preincubation of minced prostatic tissue with the 5-HT1A receptor agonist 8-hydroxy-2-(di-N-propylamino)-tetralin (8-OH-DPAT) in different experimental conditions shows the possibility of desensitisation mechanisms with switching from inhibitory to stimulatory pattern on adenylate cyclase activity. As in the majority of systems, we observed the inhibition of forskolin-stimulated adenylate cyclase activity as a functional correlate of 5-HT1A receptor activation. A similar feature occurred when the direct stimulation of the enzyme by the diterpene was replaced by a receptor-mediated activation with the neuropeptide vasoactive intestinal peptide. Furthermore, 8-OH-DPAT stimulated nitric oxide synthase (NOS) activity in a dose-dependent manner. Thus, serotonin appears to be able to act in the rat prostate gland through specific 5-HT1A receptors coupled to a complex system of signal transduction involving an inhibitory response of adenylate cyclase that can become stimulatory, as well as an enhancement of NOS activity.

Specific effect of arachidonic acid on 17beta-hydroxysteroid dehydrogenase in rat Leydig cells

It is well known that arachidonic acid (AA) acts as an intratesticular factor regulating luteinizing hormone-mediated testicular steroidogenesis. The present studies were conducted to determine the effect of AA on steroidogenic enzymes in rat Leydig cells. Exogenously added AA significantly inhibited 22(R)-hydroxy-cholesterol-stimulated testosterone production, which is a clear indication that AA is acting at some point after cholesterol transport to the inner mitochondrial membrane. AA failed to block the conversion of 22(R)-hydroxycholesterol to pregnenolone, indicating that the cytochrome P-450 side-chain cleavage enzyme complex is not the site of inhibition. The present results demonstrate that only 17beta-hydroxysteroid dehydrogenase seems to be involved in the AA action, since nearly 60% inhibition of testosterone production was found when the cells were incubated with androstenedione. Furthermore, no effect of AA was found when androstenediol was used as substrate in the testosterone synthesis, which indicates that 3beta-hydroxysteroid dehydrogenase is not affected by AA. The conversion of AA to its metabolites is not required for its action on 17beta-hydroxysteroid dehydrogenase and the activation of protein kinase C is not involved in the inhibitory effect.

Inhibitory effect of cyclosporin A peptide on rat hepatocytes proliferation induced by mitogens

Treatment of cultured rat hepatocytes with cyclosporin A (0.01-1 microM) for 24, 48, or 72 h in the presence of insulin and epidermal growth factor induced an inhibition on cell proliferation in a time- and concentration-dependent manner, with an IC50 = 0.05 microM CsA corresponding to 48-h treatment. The inhibitory effect of CsA at < or = 0.1 microM doses for 48 h on [3H]thymidine uptake was reversed after withdrawal of the drug and subsequent addition of insulin plus EGF or serum; however, at 1 microM CsA the effect was irreversible and numerous bright small vesicles were observed. The molecular mechanism involved in CsA action in hepatocytes seems to be independent on cAMP and pertussis-toxin sensitive G proteins.

G-proteins and beta-adrenergic stimulation of adenylate cyclase activity in the diabetic rat prostate

BACKGROUND

The consequences of experimental diabetes on membrane lipids, beta-adrenergic stimulation of adenylate cyclase activity, and G-protein levels in the prostate gland are not defined.

METHODS

Prostatic membranes from control and streptozotocin (STZ)-diabetic rats were used to study adenylate cyclase stimulation as well as for immunodetection of stimulatory (alpha s) and inhibitory (alpha i) G-protein subunits. Changes in membrane lipid composition were estimated by [1-14C] acetate incorporation into lipid subclasses.

RESULTS

The efficacy of isoproterenol on stimulation of adenylate cyclase activity and the levels of alpha s, alpha i1/2, and alpha i3/0 G-protein subunits were drastically reduced in prostatic membranes from STZ-diabetic rats. Insulin treatment of diabetic rats tended to normalize G-protein levels, but it was ineffective on the poor adenylate cyclase response to isoproterenol or forskolin. However, it prevented enzyme desensitization to vasoactive intestinal peptide. The pattern of [1-14C] acetate incorporation into lipid subclasses did not vary with diabetes or insulin treatment.

CONCLUSIONS

STZ-induced diabetes results in desensitization for the beta-adrenergic response of adenylate cyclase, as supported by previous data on the low density of beta-adrenergic receptors and the present results on the general decrease of Gs and Gi proteins levels and even of the enzyme itself in the diabetic rat prostate.

Ontogenic development of the adenylyl cyclase enzyme and the alpha s, alpha i1 and alpha i2 G-protein regulatory subunits from rat prostate

The expression of alpha s, alpha i1 and alpha i2 G-protein subunits measured by immunoblot increased in the rat prostate during sexual maturation, supporting their involvement in proliferation/differentiation. Northern blotting gave transcripts of 1.8 and 4 kb for alpha s, 1.4 and 4.5 kb (mainly) for alpha i1, and 2.4 kb for alpha i2 with levels suggesting a differential regulation (at transcription or post-transcription for alpha s, transcription for alpha i1, and translation for alpha i2). The stimulatory effects of forskolin, vasoactive intestinal peptide (VIP) and isoproterenol on adenylyl cyclase activity increased between 0.5-3 mo, remained constant up to 12 mo and decreased thereafter, conceivably following the expression of VIP and beta-adrenergic receptors. However, G-protein activation of adenylyl cyclase (by GTP and Gpp[NH]p) was maximal at 0.5 mo and then decreased as it occurred with toxin-catalyzed ADP-ribose incorporation to alpha subunits suggesting that other factors are also involved in the regulation of G-protein activity during rat prostatic development.

[Clinical identification of hereditary ataxias. A study of 38 cases in Colombia]

INTRODUCTION

Hereditary ataxias are a complex group of degeneratives diseases of the CNS. Material and methods. We studied 38 patients who were diagnosed inherited ataxia according to recent classification and radiologic criteria. We proposed flow sheet in order to reduce the cost of the studies.

RESULTS

The most frequent findings we encountered were the congenital ataxias and the late onset ataxia forms, olivopontocerebellar ataxias (OPCA) and the late cortical cerebellar ataxias (CCA), following were the Friedreich ataxias, the intermittent ataxias, and cerebellar ataxias with myoclonus. We found finally two multisystemic atrophies. We didn't find dominant inheritance in the late onset ataxias, some of these were recessive forms and the others could be the novo mutations or idiopathic cerebellar ataxias of adult onset.

CONCLUSION

It would be appropriate to enlarge the studies in the metabolic and treatable forms and try to define the forms that have a known genetic mutation.

Identification of a protein-tyrosine phosphatase (SHP1) different from that associated with acid phosphatase in rat prostate

Using [32P]poly(Glu,Tyr) as substrate, we have identified, for the first time, in the rat prostatic gland a protein-tyrosine phosphatase activity different from that associated with prostatic acid phosphatase. Concanavalin A-Sepharose 4B was used to separate the two protein-tyrosyl phosphatases activities. The activity retained by the lectin had characteristics of the prostatic acid phosphatase. It was sensitive to inhibition by PNPP and the optimum pH shifted towards physiological values when [32P]poly(Glu,Tyr) was used as substrate. However, the major protein-tyrosine phosphatase activity was not retained by the lectin, and corresponded, at least in part, to SHP1 as probed by the presence of the protein, its mRNA and the loss of PTPase activity after immunodepletion of SHP1. This enzyme is localized within the epithelial cells. Thus, the coexistence of two protein-tyrosine phosphatase activities in rat prostate, one associated with the acid phosphatase and the other related to SHP1, makes it necessary to analyze the importance of both activities in vivo and their possible function regarding prostatic cell growth and its regulation.

[Prognostic value of noninvasive makers of coronary reperfusion in patients with acute myocardial infarction treated with thrombolysis]

BACKGROUND

The immediate prognosis of patients with acute myocardial infarction treated with thrombolysis primarily depends on obtaining a satisfactory coronary reperfusion.

AIM

To assess the prognostic power of four markers of coronary artery patency in patients with acute myocardial infarction treated with Streptokinase 1.5 million U within the first six hours of symptoms.

PATIENTS AND METHODS

In 807 consecutive patients from the Chilean National Registry of Acute Myocardial Infarction we analyzed the resolution of chest pain and ST segment elevation over 50% within the first 90 min, abrupt CK rise within 8 h and T wave inversion in infarct related EKG leads within the first 24 h after thrombolysis.

RESULTS

Global in-hospital mortality was 12.1%. Mortality of patients with the presence of 3 or 4 markers of coronary artery patency was 5.1%, in those with resolution of ST elevation and abrupt CK rise was 6.25% and in those with T wave inversion it was 3.9% (p < 0.001). Multivariate analysis, adjusted by age, gender, risk factors, Killip class and infarct location showed that early T wave inversion was the better predictor of a low in-hospital mortality and that its combination with other markers of coronary artery patency did not increase its prognostic power. Early CK rise and the presence of 3 out of 4 reperfusion criteria were also independent predictors of a low mortality.

CONCLUSIONS

Non invasive markers of coronary artery patency are associated with a lower in-hospital mortality and may serve as surrogate end points in clinical trials.

Characterization of adenylyl cyclase stimulated by VIP in rat and mouse peritoneal macrophage membranes

Vasoactive intestinal peptide (VIP) stimulated adenylyl cyclase activity in rat and mouse peritoneal macrophage membranes. GTP potentiated the stimulatory effect of VIP so that it was routinely included at 10 microM GTP. Other agents like GTP, Gpp(NH)p, GTP-gamma-S, sodium fluoride, and forskolin, at a concentration of 0.1 mM, increased the basal activity of enzyme by 3.1, 5.7, 4.7, 3.6, and 7.8-fold, respectively. The stimulation of adenylyl cyclase by VIP was time, temperature, and membrane concentration dependent. Half-maximal enzyme activation (ED50) was very similar in rat and mouse peritoneal macrophage membranes (1.5 +/- 0.1 nM and 1.0 +/- 0.1 nM, respectively). However, VIP showed more efficacy in mouse macrophages membranes (about 3.1-fold basal values) than that in rat macrophage membranes (about 2.5-fold basal values). The relative potency of several peptides upon stimulation of adenylyl cyclase activity showed the following potency in both species: VIP = PACAP38 = PACAP27 > helodermin > PHI > secretin. On the other hand, a M(r)-45 kDa alpha s subunit of Gs protein was demonstrated by both ADP-ribosylation and immunoblot in mouse and rat peritoneal macrophage membranes. The present results, together other previous, strongly suggest that VIP play an important role in the regulation of macrophage function.

Characterization of vasoactive intestinal peptide/pituitary adenylate cyclase-activating peptide receptors in human benign hyperplastic prostate

Vasoactive intestinal peptide (VIP) is an important member of the group of neuropeptides that appears to be involved in the regulation of prostatic growth and function. Here we studied VIP receptors in membranes from human benign hyperplastic prostate. Accordingly to observations in rat prostatic membranes, [125I]VIP binding to human prostatic membranes suggested two classes of binding sites with high Kd = 0.22 nM) and low (Kd = 37.7 nM) affinities. VIP bound in human and rat membrane preparations to a common VIP/pituitary adenylate cyclase-activating peptide (PACAP) receptor, as VIP, PACAP-27, and PACAP-38 were equipotent for competition of [125I]VIP binding. A PACAP-preferring receptor appears to be expressed in human prostate, since [125I]PACAP binding was displaced with more potency by PACAP than by VIP, and a messenger RNA corresponding to type I PACAP receptor was found. Cross-linking experiments suggested a VIP receptor of about 71 kDa in human and 52 kDa in rat prostates. The binding of [125I]VIP to membranes and the labeling of the bands observed after electrophoresis were competitively inhibited by GTP, suggesting the coupling of VIP receptors to a G protein. Moreover, after solubilization and cross-linking, we observed a 120-kDa band that corresponded to the VIP receptor-alpha s association. VIP stimulated adenylyl cyclase activity in a dose-dependent manner, but the potency and/or the efficacy of VIP were lower in all human preparations studied than in rat prostatic membranes. In conclusion, this study clearly demonstrates the expression of VIP/PACAP common receptors associated with alpha s protein in human prostate and suggests that these neuropeptides could play an important and complex role in the physiology and pathophysiology of this human gland.

[Acute myocardial infarction in Chile: differences between men and women in its evolution and prognosis. Multicenter Study Group on Infarction] (GEMI)]

BACKGROUND

Gender may be a prognostic factor for the evolution of acute myocardial infarction and women may have higher mortality and complication rates.

AIM

To study if there are differences in the evolution of acute myocardial infarction between men and women.

PATIENT AND METHODS

We have recorded information on risk factors, clinical evolution, treatment and complications of 2,052 patients hospitalized for acute myocardial infarction in 36 Chilean hospitals. The odds ratio for female sex and mortality was calculated using a logistic regression analysis adjusted for risk factors, treatment, invasive procedures and complications.

RESULTS

Twenty six percent of analyzed patients were female. Mortality rates among females and males were 11.8 and 20.2% respectively (p < 0.01). Women had higher frequency of smoking, diabetes, obesity and hypertension. Blood lipid levels were similar in both sexes. Compared to men, a lesser proportion of women were treated with thrombolytic agents (25 and 35% respectively), intravenous heparin (54 and 61% respectively), beta blockers (31 and 42% respectively) and intravenous nitrates (53 and 61% respectively). Also, women were subjected to less invasive procedures. The odds ratio for mortality and sex was 1.72 (confidence interval from 1.13 to 2.62).

CONCLUSIONS

Female sex is an independent risk factor for acute myocardial infarction mortality.

Treatment of actinic prurigo in Chimila Indians

BACKGROUND

Actinic prurigo has a high prevalence in women of child-bearing age. Its treatment has been, among others, with thalidomide. To avoid the deleterious effects of this drug on the embryo, therapeutic alternatives have been sought. Among these, tetracycline and vitamin E have been investigated as to their influence on the symptoms of actinic prurigo. Both these drugs affect superoxide radicals that are thought to be involved in the pathogenesis of actinic prurigo.

MATERIALS AND METHODS

Patients (Chimila Indians with a high prevalence of actinic prurigo) received either (a) tetracycline, 500 mg three times daily, for 6 months, or (b) vitamin E, 100 IU daily, for 6 months. The patients were seen once monthly. There were eight patients in each group.

RESULTS

Both drugs used were effective. Pruritus was remarkably improved by either treatment. None of the side effects were severe enough to lead to interruption of treatment, but the observation period posttreatment was relatively short, 4 months for tetracycline and 2 months for vitamin E. The improvement occurred in spite of the continuation of extensive exposure to the sun.

CONCLUSIONS

Tetracycline and vitamin E are efficacious in relieving the pruritus of actinic prurigo. Preliminary trials of a combination treatment with these two drugs is a new avenue which has shown in preliminary trials to yield synergistic effects which might allow the dosage of tetracycline to be reduced.

Different sites of action of arachidonic acid on steroidogenesis in rat Leydig cells

The present study in purified rat Leydig cells shows that arachidonic acid may act as an intratesticular factor regulating LH-mediated testicular steroidogenesis. Arachidonic acid decreased, in a dose-dependent manner, the LH-stimulated cAMP and testosterone levels, over 2 h incubation. Incubation of Leydig cells with arachidonic acid did not modify 125I-hCG binding to the cells as compared to control, showing that the action of arachidonic acid is not related to a decrease of hCG binding to the cells. Forskolin-stimulated cAMP and testosterone production were inhibited by 51.65 and 70.9%, respectively, in the presence of arachidonic acid (100 microM), although the ED50 for the diterpene was not changed. When isobutyl-methyl-xanthine was added to the incubation medium, the same percentage of inhibition was found indicating that arachidonic acid inhibition of cAMP production is not due to stimulation of Leydig cell phosphodiesterase activity. Pretreatment of the cells with pertussis toxin, to inactivate Gi, was also without effect on arachidonic acid inhibition of LH-stimulated cAMP production, but pertussis toxin abolished the inhibitory effects of arachidonic acid when adenylate cyclase was stimulated with forskolin. However, arachidonic acid addition resulted in inhibition of LH- and forskolin-stimulated testosterone production, even if the cells were pretreated with pertussis toxin. It can be concluded that: (1) The inhibitory effect of arachidonic acid is neither due to a decrease of hCG binding to Leydig cells nor to a stimulation of cell phosphodiesterase activity; (2) arachidonic acid modulates cAMP production at two different levels, either by activation of Gi protein and by inhibition of Gs protein or adenylate cyclase; (3) the effect of arachidonic acid on steroidogenesis is also beyond cAMP formation.