Variceal band ligation and variceal band ligation plus sclerotherapy in the prevention of recurrent variceal bleeding in cirrhotic patients: a randomized, prospective and controlled trial

BACKGROUND

The combination treatment of band ligation plus sclerotherapy has been proposed to hasten variceal eradication. The aim of this study was to assess the efficacy of band ligation alone versus band ligation plus sclerotherapy in the prevention of recurrent variceal bleeding.

METHODS

Eighty cirrhotic patients were randomized to group I (band ligation) with 41 patients or to group II (band ligation plus sclerotherapy) with 39 patients in whom polidocanol (2%) was injected 1 to 2 cm proximal to each band.

RESULTS

At baseline, both groups were similar with regard to clinical, demographic and laboratory data. Mean follow-up time (standard error) for group I was 336.5 +/- 43.4 days and for group II 386.1 +/- 40.1 days (p = 0.4). No statistical differences were observed between group I and group II in relation to recurrence of bleeding (31.7% vs. 23%, p = 0.38), treatment failure (24.4% vs. 12. 8%, p = 0.18), death (39% vs. 30.8%, p = 0.44) and variceal eradication (65.8% vs. 74.4%, p = 0.40). Group II had a significantly higher number of complications than group I, 30.8% versus 7.3%, respectively (p = 0.05). The number of bleeding related deaths was higher in group I than in group II (22% vs. 10.3%, respectively; p = 0.15).

CONCLUSIONS

No significant difference was observed between band ligation and band ligation plus sclerotherapy in prevention of recurrent variceal bleeding. Furthermore, there was a higher incidence of complications in the latter group.

Involvement of Shc and Cbl-PI 3-kinase in Lyn-dependent proliferative signaling pathways for G-CSF

Granulocyte colony-stimulating factor (G-CSF) is the major hematopoietic factor which controls the production and differentiation of granulocytes. The G-CSF receptor (G-CSFR) belongs to the superfamily of the cytokine receptors, which transduce signals via the activation of cytosolic protein tyrosine kinases (PTK). To determine the role of specific PTK in G-CSF signaling we expressed the human G-CSFR in cell lines derived from DT40 B cells, which lack either the Src-related Lyn or Syk. Wild-type (wt) and syk-deficient cells underwent increased DNA synthesis in response to G-CSF; lyn-deficient cells did not. The purpose of these studies is to identify Lyn's downstream effectors in mediating DNA synthesis. While G-CSF stimulated Ras activity in all cell lines, G-CSF failed to induce the tyrosine phosphorylation of Shc in lyn-deficient cells. G-CSF induced a statistically significant activation of Erk1/Erk2 Kinase or p90Rsk only in the wt cells. G-CSF induced the tyrosine phosphorylation of Cbl and increased activity of PI 3-kinase in wild-type and syk-deficient, but non in lyn-deficient, cells. Inhibition of Shc by over-expression of its SH2 or PTB domains or PI 3-kinase by either treatment with wortmannin or expression of the CblY731F mutant decreased G-CSF-induced DNA synthesis. Thus, the Lyn, Cbl-PI 3-kinase, and Shc/non-Ras-dependent pathways correlate with the ability of cells to respond to G-CSF with increased DNA synthesis.

The KDEL receptor regulates a GTPase-activating protein for ADP-ribosylation factor 1 by interacting with its non-catalytic domain

ADP-ribosylation factor 1 (ARF1) is a key regulator of transport in the secretory system. Like all small GTPases, deactivation of ARF1 requires a GTPase-activating protein (GAP) that promotes hydrolysis of GTP to GDP on ARF1. Structure-function analysis of a GAP for ARF1 revealed that its activity in vivo requires not only a domain that catalyzes hydrolysis of GTP on ARF1 but also a non-catalytic domain. In this study, we show that the non-catalytic domain of GAP is required for its recruitment from cytosol to membranes and that this domain mediates the interaction of GAP with the transmembrane KDEL receptor. Blocking its interaction with the KDEL receptor leaves the GAP cytosolic and prevents the deactivation in vivo of Golgi-localized ARF1. Thus, these findings suggest that the KDEL receptor plays a critical role in the function of GAP by regulating its recruitment from cytosol to membranes, where it can then act on its membrane-restricted target, the GTP-bound form of ARF1.

The role of G proteins in insulin signalling

Insulin modulates many intracellular processes including cellular metabolism, cell proliferation and cell differentiation. Some of these processes involve significant changes in the traffic of intracellular vesicles or in the structural organization of the cell. These phenomena have been linked to the activity of regulatory GTP-binding proteins. Most, if not all functions, of the insulin receptor are associated with its tyrosine kinase activity. Thus, over the past few years, a significant effort has been dedicated to elucidate the cross-talk between the tyrosine kinase activity of the receptor and the regulation of G protein-mediated pathways. Recent progress indicates that G proteins may mediate the control of several of insulin's intracellular functions. These include the regulation of the MAP kinase pathway, the activation of phospholipase D and the regulation of glucose uptake. This article discusses some recent advances in this area.

Pharmacological characteristics and regulation of 5-HT receptor-stimulated phosphoinositide hydrolysis in the rat spinal cord

In slices from immature rat spinal cord, both 5-hydroxytryptamine (5-HT) and the 5-HT2A/C receptor agonists (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and alpha-methyl-5-HT (alpha-Me-5-HT) stimulate phosphoinositide (PI) hydrolysis. PI breakdown is also increased by the 5-HT3 receptor agonist 2-Me-5-HT but not by phenylbiguanide. The effect of either 5-HT or DOI is blocked by selective 5-HT2A receptor antagonists such as spiperone and ketanserin and more markedly by mixed 5-HT2 receptor antagonists, such as ritanserin, methysergide and mesulergine, with higher affinity at the 2C subtype. The effect of 2-Me-5-HT is blocked by 5-HT2 and not by 5-HT3 receptor antagonists, indicating that 5-HT3 receptors do not directly or indirectly take part in PI hydrolysis in the spinal cord. Moreover, lesion with neonatal capsaicin of thin primary afferents to the dorsal spinal cord enhances inositol phosphate formation stimulated by 5-HT or DOI but not by 2-Me-5-HT. This lesion also increases 5-HT2A and 5-HT2C receptor density. After neonatal injection of 5,7-dihydroxytryptamine, which results in a marked loss of 5-HT content in the cord, 5-HT and 5-HT2 receptor agonists also enhance PI breakdown without a concomitant change in receptor number. The results suggest that the 5-HT-stimulated PI response in the rat spinal cord is associated only with the 5-HT2 receptor class, in particular with the 5-HT2C subtype.

[Familial hypercholesterolemia and plasma Lp(a) levels: 2 cardiovascular risk factors]

OBJECTIVE

Lipoprotein (a) (Lp(a)) is a modified LDL particle in human plasma. Elevated Lp(a) plasma concentration has been associated with increase risk of premature heart disease in most cross-sectional studies. Familial hypercholesterolemia (FH) is a genetic disorder characterized by an elevation of LDL cholesterol (LDL-C) caused by molecular defects in the LDL receptor gene. The aim of our study is to analyze Lp(a) values in a genetic diagnosed FH group without coronary heart disease (CHD) and explain the considerable variation in clinical severity of FH patients.

METHOD

We have study plasma lipids and lipoprotein levels in 60 subjects with familial hypercholesterolemia without CHD and in 74 normolipidemic controls without personal history of CHD and dyslipidemia of the Valencia area in Spain.

RESULTS

We found differences in total and LDL cholesterol levels and apo B values as expected and also in plasma Lp(a) levels and log transformed values between FH subjects and normolipidemic controls (22.3 mg/dl +/- 19.4 vs 12.5 mg/dl +/- 12.6 p = 0.001 and 1.12 +/- 0.53 vs. 0.84 +/- 0.58 p = 0.008). The percentage of FH subjects with a cut point Lp(a) value > 20 mg/dl is significantly elevated in this group (47% vs 21% p = 0.002). Because of family relationships within the entire study population we also have compared 23 FH probands with the normolipidemic controls. Again the same results have been obtained (Lp(a) levels of 23.21 mg/dl +/- 19.2 vs 12.54 mg/dl +/- 12.63 p = 0.019 and log Lp(a) values of 1.19 +/- 0.42 vs 0.84 +/- 0.58 p = 0.01).

CONCLUSION

Our results indicate that FH subjects will have a more cardiovascular risk due to the potentiation of hypercholesterolemia and elevated Lp(a) values, indicating the addition effects of two different locus implicated in premature coronary heart disease and could explain the considerable variation in clinical severity of FH.

Phospholipase D and its product, phosphatidic acid, mediate agonist-dependent raf-1 translocation to the plasma membrane and the activation of the mitogen-activated protein kinase pathway

The primary known function of phospholipase D (PLD) is to generate phosphatidic acid (PA) via the hydrolysis of phosphatidylcholine. However, the functional role of PA is not well understood. We report here evidence that links the activation of PLD by insulin and the subsequent generation of PA to the activation of the Raf-1-mitogen-activated protein kinase (MAPK) cascade. Brefeldin A (BFA), an inhibitor of the activation of ADP-ribosylation factor proteins, inhibited insulin-dependent production of PA and MAPK phosphorylation. The addition of PA reversed the inhibition of MAPK activation by BFA. Overexpression of a catalytically inactive variant of PLD2, but not PLD1, blocked insulin-dependent activation of PLD and phosphorylation of MAPK. Real time imaging analysis showed that insulin induced Raf-1 translocation to cell membranes by a process that was inhibited by BFA. PA addition reversed the effects of BFA on Raf-1 translocation. However, PA did not activate Raf-1 in vitro or in vivo, suggesting that the primary function of PA is to enhance the recruitment of Raf-1 to the plasma membrane where other factors may activate it. Finally, we found that the recruitment of Raf-1 to the plasma membrane was transient, but Raf-1 remained bound to endocytic vesicles.

Metabolic modulation of acute myocardial infarction. The ECLA (Estudios Cardiológicos Latinoamérica) Collaborative Group

BACKGROUND

Several trials have been performed in the past using glucose, insulin, and potassium infusion (GIK) for the treatment of acute myocardial infarction (AMI). Because of continuing uncertainty about the potential role of this therapeutic intervention, we conducted a randomized trial to evaluate the impact of a GIK solution during the first hours of AMI.

METHODS AND RESULTS

Four hundred seven patients with suspected AMI admitted within 24 hours of symptoms onset were enrolled. In a ratio of 2:1, 268 patients were allocated to receive GIK (high- or low-dose) and 139 to receive control. Phlebitis and serum changes in the plasma concentration of glucose or potassium were observed more often with GIK. A trend toward a nonsignificant reduction in major and minor in-hospital events was observed in patients allocated to GIK. In 252 patients (61.9%) treated with reperfusion strategies, a statistically significant reduction in mortality (relative risk [RR] 0.34; 95% CI: 0.15 to 0.78; 2P=0.008) and a consistent trend toward fewer in-hospital events in the GIK group were observed.

CONCLUSIONS

Our results confirm that a metabolic modulation strategy in the first hours of an AMI is feasible, applicable worldwide, and has mild side effects. The statistically significant mortality reduction in patients who underwent a reperfusion strategy might have important implications for the management of AMI patients. It is now essential to perform a large-scale trial to reliably determine the magnitude of benefit.

ADP-ribosylation factor proteins mediate agonist-induced activation of phospholipase D

The role of small G proteins of the ADP-ribosylation factor (ARF) and Rho families on the activation of phospholipase D (PLD) by platelet-derived growth factor (PDGF) and phorbol esters (PMA) has been investigated. The activation of PLD by PDGF and PMA was blocked by brefeldin A (BFA), an inhibitor of ARF activation, but not by Clostridium botulinum C3 exotoxin, an inhibitor of the activity of Rho. PDGF and PMA, in the presence of GTPgammaS, promoted the association of ARF and RhoA with cell membranes. Cells depleted of ARF and Rho by digitonin permeabilization showed a significant reduction of the activity of phospholipase D. Recombinant ARF was sufficient to restore agonist-induced PLD activity to digitonin-permeabilized, cytoplasm-depleted cells. In contrast, isoprenylated recombinant RhoA had no effects in this reconstitution assay. HIRcB cells were transiently transfected with wild-type and dominant-negative mutants of ARF1 and ARF6. Neither wt-ARF1 nor wt-ARF6 had any effects on agonist-dependent PLD activity. However, dominant-negative ARF1 and ARF6 mutants blocked the stimulation of PLD by PDGF but only partially inhibited the effects of PMA. These results demonstrate that ARF rather than Rho proteins mediate the activation of PLD by PDGF and phorbol esters in HIRcB fibroblasts.

The quality of private and public primary health care management of children with diarrhoea and acute respiratory infections in Tlaxcala, Mexico

In Tlaxcala, Mexico, 80% of the children who died from diarrhoea or acute respiratory infections (ARI) in 1992-1993 received medical care; in more than 70% of cases it was provided by a private general practitioner (GP). The present study evaluated the quality of case management by private and public GPs to children under five years of age with diarrhoea and ARI. During the clinical observation, the treatment and counselling given to the mother were assessed with the WHO guidelines as reference standard. A total of 41 private and 40 public GPs were evaluated for the management of diarrhoea, and 59 private and 40 public GPs for the management of ARI. For diarrhoea, half of the private GPs gave inadequate rehydration therapy, 63% gave incorrect advice on diet, 66% and 49% made an incorrect correct decision in the prescription of antimicrobial and symptomatic drugs, respectively. Public GPs generally performed better in diarrhoea management: 7% gave inadequate rehydration therapy, 13% gave wrong advice on diet, 3% made a wrong decision in the prescription of symptomatic drugs and 28% gave a wrong decision in antimicrobial prescription. In the management of ARI, 66% and 58% of private GPs made a wrong decision in the prescription of antimicrobial and symptomatic drugs, respectively, compared to 30% and 20% of public GPs, respectively. Counselling to the mother given by both private and public GPs was considered inadequate in most cases of diarrhoea and ARI. These results clearly show that private doctors, as important providers of medical care, need to be included in the strategies to improve the quality of care of children with diarrhoea and ARI. Future research needs to address the determinants of the clinical practice of private doctors in countries like Mexico.

The distribution and translocation of the G protein ADP-ribosylation factor 1 in live cells is determined by its GTPase activity

ADP-ribosylation factors (ARF) are small G proteins that play key roles in vesicular transport processes. We have studied the distribution of ARF1 in live cells using chimeras of ARF1 mutants (wild type (wt) ARF1; Q71L-ARF1 (reduced GTPase); T31N (low affinity for GTP); and (Delta)Nwt (deletion of amino acids 2–18)) with green fluorescent protein (GFP). Confocal microscopy studies showed that the wt and Q71L proteins were localized in the Golgi and cytoplasm. The (Delta)Nwt and the T31N mutants were exclusively cytoplasmic. The behavior of the wt and Q71L proteins was studied in detail. About 15% of wt-ARF1-GFP was bound to the Golgi. Bound wt-ARF1-GFP dissociated rapidly after addition of Brefeldin A (BFA). This process did not appear to be a consequence of BFA-induced disappearance of the Golgi. Photobleaching recovery showed that essentially all the ARF-GFP was mobile, although it diffused very slowly. In contrast, about 40–50% of the Q71L mutant was found in the Golgi, and its rate of dissociation in the presence of BFA was slow and biphasic. Q71L-ARF1-GFP diffused more slowly than the wt. We conclude that ARF1 proteins exist in a dynamic equilibrium between Golgi-bound and cytosolic pools, and that the translocation of ARF in live cells requires the hydrolysis of GTP by the Golgi-bound protein.

Requirement of Src kinase Lyn for induction of DNA synthesis by granulocyte colony-stimulating factor

Treatment of cells with granulocyte colony-stimulating factor (G-CSF) leads to tyrosine phosphorylation of cellular proteins. G-CSF stimulates both the activation of protein tyrosine kinases Lyn, Jak1, and Jak2 and the association of these enzymes with the G-CSF receptor. Wild-type, lyn-deficient, and syk-deficient chicken B lymphocyte cell lines were transfected with the human G-CSF receptor, and stable transfectants were studied. G-CSF-dependent tyrosyl phosphorylation of Jak1 and Jak2 occurred in all three cell lines. Wild-type and syk-deficient transfectants responded to G-CSF in a dose-responsive fashion with increased thymidine incorporation, but none of the clones of lyn-deficient transfectants did. Ectopic expression of Lyn, but not that of c-Src, in the lyn-deficient cells restored their mitogenic responsiveness to G-CSF. Ectopic expression in wild-type cells of the kinase-inactive form of Lyn, but not of the kinase-inactive form of Jak2, inhibited thymidine incorporation in response to G-CSF. These studies show that the absence of Lyn results in the loss of mitogenic signaling in the G-CSF signaling pathway and that activation of Jak1 or Jak2 is not sufficient to cause mitogenesis.

Hemostatic and hemodynamic effects of vasopressin analogue DDAVP in patients with cirrhosis

Desmopressin (DDAVP), a synthetic analogue of vasopressin, has been shown to improve the bleeding time in patients with cirrhosis. The duration of this effect and the hemodynamic changes associated with DDAVP have not been studied so far. To evaluate these issues, 14 cirrhotics with portal hypertension were studied in basal conditions and after DDAVP (0.3 uk/kg). In 8 patients, hemostatic tests were done at basal conditions and 1, 3, 6 and 24 hs after drug administration. In the remaining 6 patients, mean arterial pressure, cardiac output, portal and femoral blood flows were evaluated. Hemodynamic parameters were measured by Doppler ultrasound. DDVP caused a marked decrease in bleeding time at 1, 3, 6 and 24 hs (14 +/- 9 vs 8 +/- 3, 7 +/- 4, 6 +/- 4 and 8 +/- 4 min, respectively); the decrease was maximal and statistically significant at 6 hs (55 +/- 15%, p < 0.02) after DDAVP infusion. Bleeding time reduction was observed in every patient studied. In the hemodynamic study, DDAVP caused a mild but significant decrease in mean arterial pressure (12 +/- 8%, p < 0.05); no significant changes were observed in the rest of hemodynamic parameters studied. These findings show that DDAVP can be used to shorten the bleeding time for a period of at least 24 hs in patients with cirrhosis, without deleterious hemodynamic effects. This beneficial effect may be of potential relevance in the medical management of patients with chronic liver diseases.

ARF proteins mediate insulin-dependent activation of phospholipase D

BACKGROUND

ADP-ribosylation factors (ARFs) have been shown to activate phospholipase D (PLD), an enzyme modulated by extracellular signals, including several growth factors and, in particular, insulin. We have tested the hypothesis that ARF proteins are involved specifically in insulin-induced activation of PLD.

RESULTS

We found that in membranes obtained from HIRcB cells, a cell line derived from Rat-1 fibroblasts that overexpresses normal human insulin receptors, binding of the GTP analogue GTPgammaS to purified bovine or recombinant ARF was enhanced in the presence of insulin. Membranes obtained from cells that overexpressed a mutated, nonfunctional insulin receptor failed to stimulate ARF activation. Insulin promoted the association of ARF proteins with membranes in the presence of GTPgammaS in permeabilized cells. Insulin activated PLD in permeabilized HIRcB cells by a process that required GTPgammaS and ARF. Azido-gamma[32P]-GTP labelling of immunoprecipitated receptors revealed the presence of a unique 19 kD band; ARF proteins are approximately this size, and analysis using specific monoclonal antibodies demonstrated that ARF proteins coimmunoprecipitated with the insulin receptor. Coimmunoprecipitation of ARF with the receptor was inhibited by guanine nucleotides and stimulated by insulin. No evidence of the coprecipitation of ARF with mutant receptors could be obtained using azido-gamma[32P]-GTP or anti-ARF antibodies.

CONCLUSIONS

The activation of ARF proteins is stimulated by insulin and this process plays an important role in insulin-mediated regulation of PLD.

VB20B7, a novel 5-HT-ergic agent with gastrokinetic activity. I. Interaction with 5-HT3 and 5-HT4 receptors

This study describes the in-vitro interaction of the gastrokinetic agent 2[1-(4-piperonyl)piperazinyl]benzothiazole (VB20B7) with the 5-hydroxytryptamine 5-HT3 and 5-HT4 receptor subtypes, using functional as well as radioligand binding studies. The benzamide derivative cisapride was used as a comparison. In radioligand binding assays VB20B7 showed, like cisapride, a weak affinity at 5-HT3 receptors from rat cerebral cortex. The new compound lacked any affinity at other 5-HT receptors or at dopaminergic D2 receptors, whereas cisapride showed high affinity for the 5-HT4 receptors from guinea-pig hippocampus and moderate affinity at dopaminergic D2 receptors. In the non-stimulated guinea-pig ileum, the concentration-response curves to the specific 5-HT3 agonist 2-Me-5-HT and to 5-HT were shifted to the right by VB20B7. In the rat oesophagus tunica muscularis mucosae preparation (TMM), VB20B7 was evaluated for its activity at 5-HT4 receptors. VB20B7 behaved as a 5-HT4 receptor agonist, inducing a concentration-dependent relaxation of the preparation precontracted with carbachol. In this preparation, VB20B7 and cisapride were able to stimulate adenylate cyclase activity, an effect probably mediated through activation of 5-HT4 receptors, as can be inferred from the blockade by the 5-HT4 antagonist, tropisetron, of the enhanced cAMP formation. However, consistent with the lack of affinity at central 5-HT4 receptors, VB20B7 did not stimulate cAMP formation in guinea-pig hippocampal slices. VB20B7 also caused an increase in the twitch response of the transmurally stimulated guinea-pig ileum, although at a concentration higher than cisapride. This effect was blocked by desensitization of the 5-HT4 receptor with 5-MeOT and also by the 5-HT4 receptor antagonist tropisetron. Both VB20B7 and cisapride increased the K(+)-evoked acetylcholine release in this preparation. The results show that VB20B7 possesses affinity for 5-HT4 receptors located in the rat TMM and guinea-pig ileum preparations, but is devoid of affinity at central 5-HT4 receptors. In addition, VB20B7 shows low to moderate affinity at both central and peripheral (enteric) 5-HT3 receptors. The interaction of VB20B7 with the peripheral 5-HT4 and 5-HT3 receptors may be relevant for the gastrokinetic effects of the new compound.

Total volume paracentesis decreases variceal pressure, size, and variceal wall tension in cirrhotic patients

It has been suggested that ascites is a risk factor for variceal bleeding in cirrhotic patients. However, no data of total volume paracentesis (TVP) effects on variceal hemodynamics has yet been published. The aim of this study was to investigate the effects of TVP on variceal pressure, size, and tension in cirrhotic patients. Before sclerotherapy, 18 cirrhotic patients with grade II esophageal varices were studied. The following measurements were performed on 12 patients at basal condition and after TVP: inferior vena cava pressure, esophageal pressure (EP), and intravariceal pressure (IVP) by direct punction and variceal size at endoscopy. The same measurements were performed at basal condition and 1 hour later without TVP on the other 6 patients used as a control group. Variceal pressure gradient (VPG) and variceal wall tension (WT) were calculated. Paracentesis and intra-abdominal pressure were obtained with a direct punction. No demographic differences were observed between both groups. Paracentesis produced a significant reduction of IVP (from 25.6 +/- 2.4 to 17.9 +/- 2.1 mm Hg, means +/- SEM, -30%, P < .05), VPG (from 16.6 +/- 2.4 to 10.8 +/- 1.4 mm Hg, -35%, P < .05). TVP also reduced variceal size (from 9 +/- 0.3 to 5.6 + 0.4 mm, -38%, P < .05) and WT (from 75.3 +/- 11.6 to 30 +/- 4.7 mm Hg. mm, -60%, P < .05). Intra-abdominal pressure decreased from 18 +/- 2.2 to 4 +/- 0.9 mm Hg (P < .05), and IVC decreased from 15.5 +/- 2.4 to 5.7 +/- 1.5 mm Hg (P < .05). No significant differences were observed in mean arterial pressure and heart rate. The mean ascitic fluid removed was 8 +/- 0.71 L. No significant difference between measurements was observed in the control group. Our results show that TVP significantly decreases variceal pressure and tension. These results suggest that ascites removal can be useful in the treatment of variceal bleeding in cirrhotic patients.

Mothers' health-seeking behaviour in acute diarrhoea in Tlaxcala, Mexico

This study, a cross-sectional survey, was conducted to assess how mothers take care of their children with diarrhoea and to develop a model of health-care seeking behaviour. Multistage sampling was used. Mothers whose children aged less than five years had suffered from diarrhoea in the last fortnight were included. Nurses interviewed the mothers to collect data. Variables included in the interview were: mothers' characteristics, children's characteristics, clinical data, treatment given by the mother, maternal health-seeking behaviour and mothers' information about diarrhoea and dehydration. Variables corresponding to the clinical data were grouped to identify dehydration signs and the need for medical care. Dehydration was defined as the presence of two or more of the following reported signs: thirst, sunken eyes, sunken fontanelle, or scanty urine. The need for medical care was defined as the presence of one or more of the following characteristics: illness lasting more than three days, vomiting, fever, bloody diarrhoea or dehydration. A sample of 747 mothers was obtained. Household treatments consisted of herbal teas to stop diarrhoea (52.3%), liquids to prevent dehydration (92.2%), symptomatic drugs (35.2%) and changes in feeding patterns (36.3%), which consisted in suppressing milk and dairy products and interrupting breast feeding (12.2%). Mothers sought medical assistance when they perceived a worsening of clinical conditions. Clinical signs statistically associated with their decision were: bloody diarrhoea, vomiting, illness longer than three days, weight loss, and fever. The signs of dehydration were not associated with health care-seeking because the mother did not recognise them. It is concluded that maternal educational programmes should emphasise, besides the proper use of oral rehydration therapy, teaching mothers to identify signs of dehydration as an indication to seek timely medical care.

Pharmacological properties of quinoxaline derivatives as a new class of 5-HT3 receptor antagonists

The pharmacological profile of five quinoxaline derivatives, a new class of 5HT3 receptor antagonists, is reported in the present study. All of the new compounds antagonized the effect of the selective 5-HT3 receptor agonist 2-methyl-5-HT in the isolated longitudinal muscle-myenteric plexus preparation (LMMP) of guinea-pig ileum. One of them, VC-605) was approximately three orders of magnitude more potent than ondansetron. In binding studies to 5-HT3 receptors from rat cerebral cortex membranes only VC-605 showed an affinity comparable to ondansetron. In the isolated rat oesophageal tunica muscularis mucosae preparation the new compounds, like 2-methyl-5-HT, only produced relaxation of the contraction induced by carbachol at high concentrations. In vivo, the quinoxaline derivatives were weak antagonists of the bradycardia response to 5-HT in the anesthetized rat. The quinoxaline derivatives, in particular VC-501 and VC-603, prevented retches and vomiting induced by 2-methyl-5-HT and cis-platinum in the ferret. The new compounds also enhanced the gastric emptying of solids in rats. The results obtained are probably indicative of the suggested species- and tissue-dependent differences in 5-HT3 receptor subtypes. The high potency and selectivity of one of the new quinoxaline derivatives, VC-605, at 5-HT3 receptors of guinea-pig ileum is remarkable. VC-605 may be a useful tool for further characterizing this possible 5-HT3 receptor subtype.

Lovastatin inhibits the stimulation of mitogen-activated protein kinase by insulin in HIRcB fibroblasts

Lovastatin, a cholesterol biosynthesis inhibitor, has recently been shown to inhibit mitogenesis and tumor growth. We have investigated the effects of lovastatin on the activation of MAP kinase by insulin using as a model HIRcB cells, a rat fibroblast cell line that overexpresses the human insulin receptor. Treatment with lovastatin (1-30 microM) for 24 h decreased the level of activation of MAP kinase by insulin by as much as 60%. Immunoblotting experiments using a specific anti-MAP kinase monoclonal antibody demonstrated that the amount of MAP kinase protein in the cells was not altered by lovastatin treatment. Likewise, lovastatin had no apparent effects on the expression of the insulin receptor. Treatment with lovastatin (20 microM) reduced the percentage of farnesylated Ras by 50%. Immunoprecipitation of tyrosine phosphorylated proteins from HIRcB cell lysates followed by immunodetection of MAP kinase using specific antibodies demonstrated a reduced level of insulin-induced tyrosine phosphorylation levels of MAP kinase in lovastatin-treated cells. Furthermore, immunodetection of the beta-subunit of the insulin receptor in anti-phosphotyrosine immunoprecipitates revealed that treatment with lovastatin reduced the tyrosine phosphorylation levels of the receptor. Lysates obtained from cells treated with increasing concentrations of lovastatin demonstrated a dose-dependent inhibition of the insulin-induced tyrosine phosphorylation of the receptor. Treatment with mevalonic acid prevented the effects of lovastatin demonstrating that the effects of the drug are a consequence of its inhibitory effects on the synthesis of steroids. It is concluded that, in addition to inhibition of Ras farnesylation, lovastatin reduces receptor tyrosine phosphorylation levels which also contributes to the blockade of MAPK activation by the insulin receptor.

Role of glycosyl-phosphatidylinositol hydrolysis as a mitogenic signal for epidermal growth factor

We have investigated the role of the hydrolysis of glycosyl-phosphatidylinositol (GPI) as one of the signalling pathways elicited after interaction of epidermal growth factor (EGF) with its specific plasma membrane receptor (EGFR). Endogenous GPI was characterized in both NIH 3T3 mouse fibroblast cells and in EGFR-transfected NIH 3T3 cells (designated EGFR T17). GPI molecules isolated from both cell lines were identical and they incorporated radioactivity from both sugar and fatty acid substrates. Incubation of EGFR T17 cells with EGF, produced a rapid and transient hydrolysis of GPI. Maximum hydrolysis occurred after a 1-min incubation with 50 nM EGF. No such effects of EGF were observed in the parental cell line. Both inositol phosphoglycan (IPG)- and EGF-induced cell proliferation was inhibited in the presence of an IPG-antibody to different extents. The relationship between GPI hydrolysis and the activity of the EGFR was studied using the tyrosine kinase inhibitors tyrphostin (RG50864) and genistein. These agents were able to significantly inhibit EGF-mediated cell proliferation, EGF-dependent hydrolysis of GPI and EGF-regulated autophosphorylation of the EGFR. It is concluded that GPI hydrolysis is one of the earliest intracellular events generated in response to EGF.

Brefeldin A inhibits insulin-dependent receptor redistribution in HIRcB cells

Brefeldin A (BFA) is a potent inhibitor of intracellular vesicle traffic. We have investigated the effects of BFA on the traffic of the insulin receptor in HIRcB cells, a cell line derived from Rat-1 fibroblasts that over-expresses a normal human insulin receptor. We report here that insulin-dependent receptor redistribution is inhibited by BFA and that this drug has no effects on the insulin-dependent redistribution of the receptor. Auto-phosphorylation of the insulin receptor and the stimulation of mitogen-activated protein kinase (MAPK) by insulin were not affected by treatment with the drug. The effects of BFA were further shown to require addition of the drug prior to the addition of insulin. BFA added 10 min after stimulation with insulin had no effects on the redistribution of the receptor. Dose-response studies demonstrated that the effects of BFA were half-maximal at a dose of 1 microgram/ml and maximal at about 10 micrograms/ml. These findings suggest that BFA blocks an early step in the chain of events that lead to insulin receptor internalization without affecting the interactions of the receptor with insulin, the stimulation of the tyrosine kinase activity of the receptor by the hormone, or other insulin-regulated signalling pathways, such as the activation of MAPK.

The pharmacology of VA21B7: an atypical 5-HT3 receptor antagonist with anxiolytic-like properties in animal models

VA21B7 (3-[2-(4'-piperonylpiperazinyl) indolyl] carboxaldehyde) was synthesized as a potential 5-HT3 receptor antagonist. Even though VA21B7 showed a higher affinity towards 5-HT3 receptors as compared to other receptors studied, it was not a potent 5-HT3 receptor antagonist either in the periphery or in the brain. In a simple animal model of anxiety such as the two-compartment box in mice, a remarkable anxiolytic-like effect was found at doses of 2-500 micrograms/kg IP and also at low oral doses, in the microgram range. These drug doses did not produce any significant effect on spontaneous motor activity of mice. The anxiolytic profile of VA21B7 was further explored using other models of anxiety in rats such as the elevated plus-maze and punished-drinking. VA21B7 was compared with standard 5-HT3 receptor antagonists such as ondansetron, tropisetron and granisetron, with the 5-HT1A agent buspirone and with diazepam. In the plus-maze, VA21B7 showed an anxiolytic-like profile after doses of 0.25-0.5 mg/kg IP or 2-4 mg/kg PO which did not modify the number of total entries into the open and closed arms of the maze. Diazepam, granisetron and tropisetron were also effective in this test but not ondansetron and buspirone. VA21B7 was also able to release suppressed behaviour in the punished-drinking test. The dose-response curve was bell-shaped with a peak at 2-4 mg/kg. At variance with other studies, 5-HT3 receptor antagonists also increased the number of shocks taken in this test and the dose-response curve was also bell-shaped. VA21B7 was not anticonvulsant like diazepam, its anxiolytic action in the light/dark test was not flumazenil-sensitive and there was no rebound anxiogenic effect on withdrawal from chronic VA21B7 treatment for 15 consecutive days. Moreover, VA21B7 was not amnesic like the benzodiazepines but low doses of 2-4 mg/kg reduced the memory deficits induced in rats by scopolamine. Much higher doses were necessary to decrease spontaneous motor activity in rats. Since VA21B7 appears to be well tolerated in rodents at high doses, we think that it is of potential interest as an anxiolytic in humans.