[IGF-1 plasma levels evaluation in prolactinoma]. / Avaliação plasmática de IGF-1 no prolactinoma.

Prolactinomas are the most frequent pituitary tumors and may co-secrete GH (growth hormone). IGF-1 (insulin-like growth factor-1) is the main responsible for GH actions and a parameter for the diagnosis of acromegaly. With the objective of identifying through a IGF-1 levels analysis, in the initial evaluation of prolactinoma patients, the existence of mixed tumors [GH and prolactin (PRL)], we studied 7 men and 27 women, aged between 19 and 72 years, confronting them with the results of basal and glucose stimulated (glucose tolerance test--GTT) GH levels, indicated when GH >0.4 ng/mL or IGF-1 levels were elevated. The prevalence of patients with GH >0.4 ng/mL and elevated IGF-1 was higher than expected; however, after GTT, no patient fulfilled the diagnostic criteria for acromegaly. However, we suggest that, they should be submitted to IGF-1 evaluation, due to the risk of GH co-secretion in prolactinomas. Special attention should be paid to those who present a significant decrease of PRL levels without concomitant tumor size reduction.

Avaliação plasmática de igf-1 no prolactinoma / IGF-1 plasma levels evaluation in prolactinoma

Prolactinomas são os tumores hipofisários mais comuns, podendo co-secretar GH (hormônio do crescimento). IGF-1 (fator de crescimento insulina-símile-1) é o principal responsável pelas ações do GH e parâmetro diagnóstico de acromegalia. Objetivando determinar por uma dosagem de IGF-1, na avaliação inicial de pacientes com prolactinoma, ocorrência de tumores mistos [GH e prolactina (PRL)], estudamos 7 homens e 27 mulheres, entre 19 e 72 anos, confrontando-os aos resultados de GH basal e durante teste oral de tolerância à glicose, quando GH basal >0,4 ng/mL ou níveis de IGF-1 alterados. A proporção de pacientes com GH >0,4 ng/mL e IGF-1 elevada foi alta; mas, após administração de 75g de glicose por via oral, nenhum paciente foi diagnosticado como acromegálico. Sugerimos, porém que a dosagem de IGF-1 seja realizada pelo risco de co-secreção de GH nos prolactinomas. Atenção especial para pacientes que apresentem significativa diminuição dos níveis de PRL, sem correspondente regressão do tamanho do adenoma.

Prolactinomas are the most frequent pituitary tumors and may co-secrete GH (growth hormone). IGF-1 (insulin-like growth factor-1) is the main responsible for GH actions and a parameter for the diagnosis of acromegaly. With the objective of identifying through a IGF-1 levels analysis, in the initial evaluation of prolactinoma patients, the existence of mixed tumors [GH and prolactin (PRL)], we studied 7 men and 27 women, aged between 19 and 72 years, confronting them with the results of basal and glucose stimulated (glucose tolerance test - GTT) GH levels, indicated when GH >0.4 ng/mL or IGF-1 levels were elevated. The prevalence of patients with GH >0.4 ng/mL and elevated IGF-1 was higher than expected; however, after GTT, no patient fulfilled the diagnostic criteria for acromegaly. However, we suggest that, they should be submitted to IGF-1 evaluation, due to the risk of GH co-secretion in prolactinomas. Special attention should be paid to those who present a significant decrease of PRL levels without concomitant tumor size reduction.

Clinical and epidemiological aspects of children hospitalized with severe rotavirus-associated gastroenteritis in Salvador, BA, Brazil

Little is known about the epidemiology of severe rotavirus-associated gastroenteritis in Brazil. Given the morbidity associated with this condition and the importance of having detailed knowledge about the impact of rotavirus infection on the epidemiology of acute diarrhea in children, especially those with the most severe diarrheal conditions, we retrospectively reviewed the medical records of all pediatric patients admitted to a tertiary hospital in Salvador, Brazil, due to rotavirus-associated gastroenteritis during one year. It was observed that rotavirus was responsible for 15.6 percent of the hospitalizations caused by diarrhea and/or vomiting during the period of the study and that 87 of 218 (39.1 percent) patients seen at the emergency room with rotavirus-associated gastroenteritis needed to be hospitalized, comprising the population of our study. Most patients presented signs of dehydration, and 41 percent of them had metabolic acidosis. Most patients (79 percent) were between six months and four years of age and 72 percent of the cases occurred in June and July. Gastrointestinal symptoms were rarely present at the beginning of the clinical presentation, and they normally did not last for more than one week.

Clinical and epidemiological aspects of children hospitalized with severe rotavirus-associated gastroenteritis in Salvador, BA, Brazil.

Little is known about the epidemiology of severe rotavirus-associated gastroenteritis in Brazil. Given the morbidity associated with this condition and the importance of having detailed knowledge about the impact of rotavirus infection on the epidemiology of acute diarrhea in children, especially those with the most severe diarrheal conditions, we retrospectively reviewed the medical records of all pediatric patients admitted to a tertiary hospital in Salvador, Brazil, due to rotavirus-associated gastroenteritis during one year. It was observed that rotavirus was responsible for 15.6% of the hospitalizations caused by diarrhea and/or vomiting during the period of the study and that 87 of 218 (39.1%) patients seen at the emergency room with rotavirus-associated gastroenteritis needed to be hospitalized, comprising the population of our study. Most patients presented signs of dehydration, and 41% of them had metabolic acidosis. Most patients (79%) were between six months and four years of age and 72% of the cases occurred in June and July. Gastrointestinal symptoms were rarely present at the beginning of the clinical presentation, and they normally did not last for more than one week.

Structure-activity relationships of pyrazole derivatives as cannabinoid receptor antagonists.

As a potent, specific antagonist for the brain cannabinoid receptor (CB1), the biarylpyrazole N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716A; 1) was the lead compound for initiating studies designed to examine the structure-activity relationships of related compounds and to search for more selective and potent cannabimimetic ligands. A series of pyrazole derivatives was designed and synthesized to aid in the characterization of the cannabinoid receptor binding sites and also to serve as potentially useful pharmacological probes. Therapeutically, such compounds may have the ability to antagonize harmful side effects of cannabinoids and cannabimimetic agents. Structural requirements for potent and selective brain cannabinoid CB1 receptor antagonistic activity included (a) a para-substituted phenyl ring at the 5-position, (b) a carboxamido group at the 3-position, and (c) a 2,4-dichlorophenyl substituent at the 1-position of the pyrazole ring. The most potent compound of this series contained a p-iodophenyl group at the 5-position, a piperidinyl carboxamide at the 3-position, and a 2,4-dichlorophenyl group at the 1-position of the pyrazole ring. The iodinated nature of this compound offers additional utility as a gamma-enriching SPECT (single photon emission computed tomography) ligand that may be useful in characterizing brain CB1 receptor binding in vivo.

Design and synthesis of the CB1 selective cannabinoid antagonist AM281: a potential human SPECT ligand.

In the search for a radioligand capable of imaging cannabinoid CB1 receptors in the living human brain by SPECT (single photon emission computed tomography),N-(morpholin-4-yl)-1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM281) was synthesized. This compound is an analog of the potent, CB1 receptor selective antagonist SR141716A [N-(piperidin-1-yl)-1-(2,4-dichlorophenyl)-5-(4-chlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide]. AM281 bound to brain and spleen membrane preparations (CB1 and CB2 receptors, respectively) with K(i) values of 12 nM and 4200 nM, respectively. AM281 also inhibited the response of guinea-pig small intestine preparation to a cannabinoid receptor agonist. Thus, AM281 behaves as a CB1 receptor selective antagonist. Methods for the rapid, high-yield synthesis and purification of [123I]AM281 were developed, and transaxially reconstructed brain SPECT images obtained after continuous infusion of [123I]AM281 in baboons. Thus [123I]AM281 may be suitable for imaging CB1 receptors in humans.

Comparison of cannabinoid binding sites in guinea-pig forebrain and small intestine.

We have investigated the nature of cannabinoid receptors in guinea-pig small intestine by establishing whether this tissue contains cannabinoid receptors with similar binding properties to those of brain CB1 receptors. The cannabinoids used were the CB1-selective antagonist SR141716A, the CB2-selective antagonist SR144528, the novel cannabinoid receptor ligand, 6'-azidohex-2'-yne-delta8-tetrahydrocannabinol (O-1184), and the agonists CP55940, which binds equally well to CB1 and CB2 receptors, and WIN55212-2, which shows marginal CB2 selectivity. [3H]-CP55940 (1 nM) underwent extensive specific binding both to forebrain membranes (76.3%) and to membranes obtained by sucrose density gradient fractionation of homogenates of myenteric plexus-longitudinal muscle of guinea-pig small intestine (65.2%). Its binding capacity (Bmax) was higher in forebrain (4281 fmol mg(-1)) than in intestinal membranes (2092 fmol mg(-1)). However, the corresponding KD values were not significantly different from each other (2.29 and 1.75 nM respectively). Nor did the Ki values for its displacement by CP55940, WIN55212-2, O-1184, SR141716A and SR144528 from forebrain membranes (0.87, 4.15, 2.85, 5.32 and 371.9 respectively) differ significantly from the corresponding Ki values determined in experiments with intestinal membranes (0.99, 5.03, 3.16, 4.95 and 361.5 nM respectively). The Bmax values of [3H]-CP55940 and [3H]-SR141716A in forebrain membranes did not differ significantly from each other (4281 and 5658 fmol mg(-1)) but were both greater than the Bmax of [3H]-WIN55212-2 (2032 fmol mg(-1)). O-1184 (10 or 100 nM) produced parallel dextral shifts in the log concentration-response curves of WIN55212-2 and CP55940 for inhibition of electrically-evoked contractions of the myenteric plexus-longitudinal muscle preparation, its KD values being 0.20 nM (against WIN55212-2) and 0.89 nM (against CP55940). We conclude that cannabinoid binding sites in guinea-pig small intestine closely resemble CB1 binding sites of guinea-pig brain and that 0-1184 behaves as a cannabinoid receptor antagonist in the guinea-pig myenteric plexus-longitudinal muscle preparation.

Evidence that methyl arachidonyl fluorophosphonate is an irreversible cannabinoid receptor antagonist.

1. Methyl arachidonyl fluorophosphonate (MAFP) (1 microM) significantly attenuated the ability of WIN 55,212-2, CP 55,940, (-)-delta 9-tetrahydrocannabinol (THC), nabilone and (R)-(+)-arachidonoyl-1'-hydroxy-2'-propylamide (methanandamide) to inhibit electrically-evoked isometric contractions of the myenteric plexus-longitudinal muscle preparation of guinea-pig small intestine. 2. The sizes of the maximal responses to WIN 55,212-2 and CP 55,940 decreased significantly in the presence of 1 microM MAFP. 3. MAFP (1 microM) essentially abolished the inhibitory effects on the twitch response of the highest concentration of methanandamide used (3.162 microM). The dextral shift it induced in the log concentration-response curve of nabilone was non-parallel. In contrast, the dextral shift in the log concentration-response curve of THC produced by MAFP did not deviate significantly from parallelism and was relatively small with a mean value of 3.45 and 95% confidence limits of 1.19 and 13.08. 4. MAFP (1 microM) did not attenuate the effects of normorphine or clonidine on the twitch response of the myenteric plexus-longitudinal muscle preparation or affect the contractile response of this preparation to acetylcholine. 5. When administered by itself at concentrations of 1 to 1000 nM, MAFP had no detectable effect on the twitch response of the myenteric plexus-longitudinal muscle preparation. 6. These results support the hypothesis that MAFP is an irreversible cannabinoid CB1 receptor antagonist that possesses some degree of selectivity.

Evidence for the presence of CB2-like cannabinoid receptors on peripheral nerve terminals.

We have investigated whether there are cannabinoid CB2 receptors that can mediate cannabinoid-induced inhibition of electrically evoked contractions in the mouse vas deferens or guinea-pig myenteric plexus-longitudinal muscle preparation. Our results showed that mouse vas deferens and guinea-pig whole gut contain cannabinoid CB1 and CB2-like mRNA whereas the myenteric plexus preparation seemed to contain only cannabinoid CB1 mRNA. JWH-015 (1-propyl-2-methyl-3-( -naphthoyl)indole) and JWH-051 (1-deoxy-11-hydroxy-delta8-tetrahydrocannabinol-dimethylheptyl+ ++), which have higher affinities for CB2 than CB1 cannabinoid binding sites, inhibited electrically evoked contractions of both tissues in a concentration related manner. This inhibition was attenuated by 31.62 nM of the cannabinoid CB1 receptor selective antagonist SR141716A [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-me thyl-1H-pyrazole-3-carboxamide hydrochloride] only in the myenteric plexus preparation. Vasa deferentia from delta9-tetrahydrocannabinol-pretreated mice (20 mg/kg i.p. once daily for two days) showed reduced sensitivity to JWH-015 and JWH-051. The results suggest that these compounds exert their inhibitory effects through cannabinoid CB1 receptors in the myenteric plexus preparation, but mainly through CB2-like cannabinoid receptors in the vas deferens.

Agonist-antagonist characterization of 6'-cyanohex-2'-yne-delta 8-tetrahydrocannabinol in two isolated tissue preparations.

This investigation was directed at characterizing some of the pharmacological properties of 6'-cyanohex-2'-yne-delta 8-tetrahydrocannabinol (O-823), a compound with high affinity for cannabinoid binding sites (Ki = 0.77 nM). In mouse vasa deferentia, O-823 behaved as a potent partial cannabinoid CB1 receptor agonist (EC50 = 0.015 nM). In the guinea-pig myenteric plexus preparation, it antagonized WIN 55.212-2 [(R)-(+)-[2,3-dihydro-5-methyl-3-[(4-morpholino)methyl]pyrrolo-[1,2,3-de ]-1, 4-benzoxazin-6-yl](1-naphthyl)methanone] and CP 55.940 [(-)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4-(3-hydroxypropyl ) cyclohexan-1-ol] with Kd values of 0.65 and 0.27 nM, respectively. After in vivo delta 9-tetrahydrocannabinol pretreatment. the sensitivity of vasa deferentia to O-823-induced inhibition of electrically evoked contractions was reduced by 127-fold. 3.162 nM O-823 was inhibitory in unpretreated vasa deferentia but antagonized CP 55,940 in pretreated tissues (Kd = 0.26 nM). O-823 is probably an antagonist in the myenteric plexus preparation and delta 9-tetrahydro-cannabinol pretreated vasa deferentia but a partial agonist in unpretreated vasa deferentia because the first two of these preparations contain fewer receptors than the third.

Evidence for the presence of cannabinoid CB1 receptors in mouse urinary bladder.

1. CP 55,244, (-)-11-hydroxy-dimethylheptyl-delta 8-tetrahydrocannabinol, WIN 55,212-2, delta 9-tetrahydrocannabinol, nabilone and anandamide each inhibited electrically-evoked contractions of the mouse isolated urinary bladder in a concentration-related manner, their EC50 values being respectively 15.9, 18.27, 27.23, 1327.6, 1341.5 and 4950.3 nM. (+)-11-hydroxy-dimethylheptyl-delta 8-tetrahydrocannabinol was inactive at the highest concentration used (10 microM). 2. SR141716A (31.62 or 100 nM) produced parallel rightward shifts in the log concentration-response curves of CP 55,244, (-)-11-hydroxy-dimethylheptyl-delta 8-tetrahydrocannabinol, WIN 55,212-2, delta 9-tetrahydrocannabinol and anandamide for inhibition of electrically-evoked bladder contractions. The effect of the antagonist on the log concentration-response curve of CP 55,244 was shown to depend on the concentration of SR141716A used (31.62 to 1000 nM). 3. The amplitudes of contractions evoked by acetylcholine or beta, gamma-methylene-L-ATP were not decreased by 316.2 nM CP 55,244 or 3162 nM delta 9-tetrahydrocannabinol. Electrically-evoked contractions were almost completely abolished by 200 nM tetrodotoxin. 4. The above results support the hypothesis that mouse urinary bladder contains prejunctional CB1 cannabinoid receptors which can mediate inhibition of electrically-evoked contractions, probably by reducing contractile transmitter release. 5. AM 630 which behaves as a cannabinoid receptor antagonist in the mouse isolated vas deferens did not antagonize the ability of CP 55,244 or delta 9-tetrahydrocannabinol to inhibit electrically-evoked contractions of the mouse bladder. 6. SR141716A produced small but significant increases in the amplitude of electrically-evoked contractions of the bladder suggesting that this tissue may release an endogenous cannabinoid receptor agonist or that some cannabinoid receptors in this tissue are precoupled to the effector system.

Further evidence for the presence of cannabinoid CB1 receptors in guinea-pig small intestine.

1. CP 50,556, CP 55,940, nabilone, CP 56,667, delta 9 -tetrahydrocannabinol (THC) and cannabinol each inhibited electrically-evoked contractions of the myenteric plexus-longitudinal muscle preparation of guinea-pig small intestine in a concentration-related manner. The IC50 values of these cannabinoids, respectively 3.45, 3.46, 30.61, 162.94, 214.63, and 3913.5 nM, correlate well with previously obtained potency values for displacement of [3H]-CP 55,940 from cannabinoid binding sites. 2. Electrically-evoked contractions of the myenteric plexus-longitudinal muscle preparation were also inhibited by AM 630 (6-iodo-pravadoline) and by WIN 55,212-2 (IC50 = 1923.0 and 5.54 nM, respectively). The present finding that AM 630 is an agonist, contrasts with a previous observation that it behaves as a cannabinoid receptor antagonist in the mouse isolated vas deferens. 3. SR141716A produced dose-related parallel rightward shifts in the log concentration-response curves of CP 55,940, WIN 55,212-2, THC and AM 630 for inhibition of electrically-evoked contractions of the myenteric plexus-longitudinal muscle preparation. SR141716A (1 microM) did not reverse the inhibitory effects of normorphine and clonidine on electrically-evoked contractions or potentiate the contractile response to acetylcholine. 4. Doses of naloxone and yohimbine that reversed the inhibitory effects of normorphine or clonidine on electrically-evoked contractions of the myenteric plexus-longitudinal muscle preparation did not affect the inhibitory response to WIN 55,212-2. 5. Electrically-evoked release of acetylcholine from strips of myenteric plexus-longitudinal muscle was decreased by 200 nM CP 55,940 and this inhibitory effect was almost completely reversed by 1 microM SR141716A. Acetylcholine-induced contractions were not affected by 200 nM CP 55,940. 6. These results support the hypothesis that guinea-pig small intestine contains prejunctional cannabinoid CB1 receptors through which cannabinoids act to inhibit electrically-evoked contractions by reducing release of the contractile transmitter, acetylcholine. 7. THC was found to be more susceptible to antagonism by SR141716A than CP 55,940 or AM 630, raising the possibility that guinea-pig small intestine contains more than one type of cannabinoid receptor. 8. At concentrations of 10 nM and above, SR141716A produced small but significant increases in the amplitude of electrically-evoked contractions of the myenteric plexus-longitudinal muscle preparation suggesting that this tissue may release an endogenous cannabinoid receptor agonist or that some cannabinoid receptors in this tissue are precoupled and that SR141716A can reduce the number of receptors in this state.

Effect of phenylmethylsulphonyl fluoride on the potency of anandamide as an inhibitor of electrically evoked contractions in two isolated tissue preparations.

The endogenous cannabinoid receptor ligand, anandamide, produced a concentration related inhibition of electrically evoked contractions of the guinea-pig myenteric plexus preparation. Its potency was markedly enhanced by phenylmethylsulphonyl fluoride (2.0-200 microM) which presumably acts by inhibiting the hydrolysis of anandamide in this preparation. The degree of this potentiation increased with the concentration of phenylmethylsulphonyl fluoride used. The methyl analogue of anandamide, R-(+)-arachidonyl-1'-hydroxy-2'-propylamide, also inhibited contractions of the guinea-pig myenteric plexus preparation. The potency of this compound was much less affected by phenylmethylsulphonyl fluoride than was the potency of anandamide, confirming its greater resistance to hydrolysis. Phenylmethylsulphonyl fluoride did not alter the inhibitory potency of the cannabinoid, CP 55,940 ((-)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4- [3-hydroxypropyl]cyclohexan-1-ol), which is not an amidase substrate. Nor did phenylmethylsulphonyl fluoride affect the ability of anandamide to inhibit electrically evoked contractions of the mouse vas deferens, suggesting that anandamide does not undergo hydrolysis in this tissue.

The design, synthesis and testing of desoxy-CBD: further evidence for a region of steric interference at the cannabinoid receptor.

Cannabidiol CBD, a non-psychoactive constituent of marihuana, has been reported to possess essentially no affinity for cannabinoid CB1 receptor binding sites in the brain. Our hypothesis concerning CBD's lack of affinity for the cannabinoid CB1 receptor is that CBD is not capable of clearing a region of steric interference at the CB1 receptor and thereby not able to bind to this receptor. We have previously characterized this region of steric interference at the CB1 receptor [P.H. Reggio, A.M. Panu, S. Miles J. Med. Chem. 36, 1761-1771 (1993)] in three dimensions using the Active Analog Approach. We report here a conformational analysis of CBD which, in turn, led to the design of a new analog, desoxy-CBD. Modeling results for desoxy-CBD predict that this compound is capable of clearing the region of steric interference by expending 3.64 kcal/mol of energy in contrast to the 12.39 kcal/mol expenditure required by CBD. Desoxy-CBD was synthesized by condensation of 3-pentylphenol with p-mentha-2,8-dien-1-ol mediated by DMF-dineopental acetal. Desoxy-CBD was found to behave as a partial agonist in the mouse vas deferens assay, an assay which is reported to detect the presence of cannabinoid receptors. The compound produced a concentration related inhibition of electrically-evoked contractions of the mouse vas deferens, possessing an IC50 of 30.9 nM in this assay. Taken together, these results support the hypothesis of the existence of a region of steric interference at the CB1 receptor. While the energy expenditure to clear this region was too high for the parent compound, CBD, the removal of the C6' hydroxyl of CBD produced a molecule (desoxy-CBD) able to clear this region and produce activity, albeit at a reduced level.