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incubation, respectively. A minimum effective concentration required for ethanol to stimulate the low-K, GTPase was 300 mmol/L when chief cell membranes were incubated at 37°C for 30 minutes, consistent with the concentration required to stimulate increase in [Ca”], and pepsinogen release. These data suggest that ethanol activates GTP-binding protein in gastric chief cells. Because receptor desensitization or down-regulation has been suggested to be caused by the agonist-induced activation of GTP-binding protein in other systems, the activation of GTP-binding protein by ethanol in chief cells might reduce receptor-mediated signals and the subsequent pepsinogen secretion stimulated by secretagogues. Recently, it has also been reported that ethanol treatment causes desensitization of receptor-mediated phospholipase C activation in isolated (3). hepatocytes Furthermore, remarkable increases in LDH release have been shown in chief cells or gastric glands exposed to 8 or 10% ethanol for 1 hour (4,5). We feel that 5.2% ethanol, which activates membrane-associated proteins, is different from 8% or 10% ethanol causing their injury. Dr. Cherner questioned that an increase of only 50 nmol/L in [Ca”], over 5 minutes caused by ethanol can be sufficient to cause almost the same amount of pepsinogen release caused by exposure of CCK-8. We have previously shown that although NaF, a wellknown activator of G protein, stimulates pepsinogen secretion from isolated gastric chief cells following an increase in initial Ca2+ influx rate (6), the increase of Ca2+ influx does not cause an increase in [Ca”], measured by Quin-2 fluorescence. We can observe a [Ca”], increase in response to NaF for the first time using furainstead of Quin-2. However, the [Ca”], increase is slow and reached a plateau by several minutes, as did the [Ca”], increase caused by ethanol (7). Therefore, an initial increase in [Ca”], does not always explain subsequent pepsinogen secretion in gastric chief cells. Furthermore, it should be considered that calcium oscillation caused by CCK-8 stimulation was reported to be an important factor of amylase secretion from isolated pancreatic acini (8). Therefore, pepsinogen release from chief cells may also be the results of more complex phenomena. CHOITSU SAKAMOTO, M.D., PH.D. The Second Department of Internal Medicine Kobe University School of Medicine Kobe 650, Japan 1. Hoek JB, Thomas AP, Rubin R, Rubin E. Ethanol-induced mobilization of calcium by activation of phosphoinositide-specific phospholipase C in intact hepatocytes. J Biol Chem 1987;262: 682-691. 2. Bonzales RA, Theiss C, Crews FT. Effects of ethanol on stimulated inositol phospholipid hydrolysis in rat brain. Pharmacol Exp Ther 1986; 237:92-98. of receptor3. Higashi K, Hoek JB. Ethanol causes desensitization mediated phospholipase C activation in isolated hepatocytes. J BiolChem 1991;2178-2190. 4. Konda Y, Nishisaki H, Nakano 0, Matsuda K, Wada K, Nagao M, Matozaki T, Sakamoto C. Prostaglandin protects isolated guinea pig chief cells against ethanol injury via an increase in diacylglycerol. J Clin Invest 1991;86:1879-1903, 5. Tarnawski A, Brzozowski T, Sarfeh IJ, Krause WJ, Ulich TR, Gergely H, Hollander D. Prostaglandin protection of human isolated gastric glands against indomethacin and ethanol injury. J Clin Invest 1988;81:1081-1089, 6, Matozaki T, Sakamoto C, Nagao M, Nishisaki H, Konda Y, Baba S. Involvement of Ca*+ influx in F--stimulated pepsinogen release from guinea pig gastric chief cells. Biochem Biophys Res Comm 1988;152:161-165. 7 Nakano 0, Sakamoto C, Nishisaki H, Konda Y, Matsuda K, Wada K, Nagao M, Matozaki T. Difference in effects of sodium fluoride and cholecystokinin on diacylglycerol accumulation and cal-

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cium increase in guinea pig gastric chief cells. Life Sci 1990;47: 647-654. 8. Matozaki T, Goke B, Tsunoda Y, Rodriguez M, Marlinez J, Williams JA. Two functionally distinct cholecystokinin receptors show different modes of actions on Ca2+ mobilization and phospholipid hydrolysis in isolated rat pancreatic acinistudies using a new cholecystokinin analog, JMV-180. J Biol Chem 1990;265:6247-6254.

Hemodynamic Events in a Prospective Randomized Trial of Propranolol Versus Placebo in the Prevention of a First Variceal Hemorrhage Dear Sir: I read with interest the paper by Groszmann et al. (1) reporting the importance of reducing hepatic venous pressure gradient (HVPG) to < 12 mm Hg in patients receiving propranolol prophylactically to prevent first variceal hemorrhage. While the findings may appear convincing, there are a number of questions relating to the methodology and interpretation of data that require answers. First, in this report, clinical data were not provided because they were reported elsewhere (2). However, clinical results were presented only in abstract form, where paucity of information limits our interpretation of the results in the study under discussion (1). Second, the greatest benefit from propranolol therapy occurred within the first 3 months, when HVPG decreased from 18.1 + 4.2 mm Hg to 15.7 2 3.4 mm Hg (P < 0.05); six patients were lost from the propranolol group. In contrast, HVPG did not change significantly in placebo controls, decreasing from 19.6 2 6.8 mm Hg to 17.5 f 5.3 mm Hg, while 12 patients (twice the number of propranolol patients) left the study. Because 95% confidence intervals are not provided for the portal pressure measurements between the two groups, there are limitations to accepting statistical significance (3) of their findings. Also, it is curious that mean HVPG was apparently higher in the controls who left the study at 3 months (P = NS) and within 12 months (P < 0.05); in this analysis too, statistical significance or the lack of it must be reported using confidence intervals. Third, despite similar reductions in HVPG between placebo- and propranolol-treated patients observed at 12 and 24 months of the study period (which were not statistically significant), was the decrease in variceal size observed in controls as well? What was the proportion of propranolol and placebo patients in whom the decrease in variceal size was noted? What did the variceal size decrease to? Fourth, if the success of propranolol in preventing the first hemorrhage is attributed to reductions in HVPG to < 12 mm Hg, how can they explain their good results with propranolol when there was no statistically significant difference between patients in the two groups (propranolol, 31%, vs. placebo, 18%; P = 0.165) in whom HVPG decreased to < 12 mm Hg? Fifth, in Table 5, the authors compare the clinical course of patients in whom HVPG decreased to < 12 mm Hg (n = 21) with that in patients in whom no change was observed (n = 63). Cumulative survival at 48 months was significantly lower (32% + 24% vs. 86% f 13%; P < 0.05) in patients without reduction in HVPG. Ninety-five percent of patients in whom HVPG decreased to < 12 mm Hg had alcoholic liver disease, compared with 70% of those in whom HVPG did not decrease (P < 0.05). Is it possible that patients in the former group had less severe liver disease or a reversible component to portal hypertension (4), perhaps influenced by alcohol abstinence, that contributed to their improved survival rather than attributing the beneficial effect to HVPG reduction? Last, the enormous attrition in the number of patients in the study between 3 and 24 months (18% in 3 months, 40% in 12

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months, and 79% in 24 months) has not been satisfactorily explained. How is it possible to conclude that propranolol prevents the development of the first episode of variceal hemorrhage when the majority of patients “left” the study? The number of patients who left the study exceeded the number (16%) of bleeding patients. Was the “loss” of patients similar for the three centers in this study? Did the many invasive procedures performed (maximum of 5 in 21% of all patients, and out of proportion to the type of therapy offered) to evaluate the efficacy of oral medications contribute to this decrement in patient numbers? Can we make meaningful interpretations of the data? I believe answers to the these questions are essential before we can accept the conclusions that decreasing HVPG improves the success of prophylactic therapy with propranolol. JACOB KORULA, M.D., F.R.C.P.C. Liver Unit Universit,v of Southern California School of Medicine Los Angeles, California Groszmann RJ, Bosch J, Grace ND, Conn HO, Garcia-Tsao G, Navasa M, Alberts J, Rodes J, Fischer R, Bermann M, Rofe S, Patrick M, Lerner E. Hemodynamic events in a prospective randomized trial of propranolol versus placebo in the prevention of a first variceal hemorrhage. Gastroenterology I990;99: 1401-1407. Grace ND, Conn HO, Bosch J, et al. Propranolol in the prevention of first hemorrhage from esophageal varices: a multicenter controlled trial. Hepatology 1988;8:1220. Bulpitt CJ. Confidence intervals. Lancet 1987;1:494-497. Reynolds TB. Geller HM, Kuzma OT, Redeker AG. Spontaneous decrease in portal pressure with clinical improvement in cirrho1960;263:734-739. sis.NEnglJMed Reply. We thank Dr. Korula for providing us an opportunity to discuss further the findings of our study (1) and to address issues that may have not been clear to the reader. I. As the title indicates, our study reports the hemodynamic events that occurred during the clinical trial: therefore, it concentrates on hemodynamic data and on their relationship with clinical and laboratory events. The clinical portion of the study is part of a separate paper, which will be published in the May 1991 issue of Hepatology (2); therefore, only clinical data relevant to the hemodynamic findings are reported in our study. The intention of the authors was to have both manuscripts published simultaneously, but, unfortunately, this was not possible. 2. We agree that 95% confidence intervals are important when comparing two groups. In fact, in Figures 1 and 2 of the paper (11, groups are compared using this method. Furthermore, we reported the sample sizes (n), means (K), and SDS for the data presented; therefore, the 95% confidence interval can be approximated by any reader by calculating the SEM (SEM = SD/ &(95% CI = X + 2(SD/,,‘&)) (3). When comparing changes in HVPG, we emphasize the differences within each group with respect to baseline HVPG values rather than differences between the propranolol and placebo groups (although appropriate intergroup comparisons were made and are shown in Table 2). The reason for emphasizing intragroup differences is that pressure alone is not the only factor that determines variceal rupture (4). Other factors that determine the tension in the wall of the varix (such as variceal size and variceal wall thickness) may be involved in triggering variceal bleeding (4,5). Therefore, at the same portal pressure, the risk of bleeding could vary widely from patient to patient. However, a decrease in portal pressure in the individual patient wall tension and, by this mechanism, will reduce variceal decrease the risk of variceal hemorrhage. At present, all factors

involved

in variceal

rupture

cannot

comparison of HVPG between groups Patients that “left the study” did are mentioned in the text and in point was higher in patients in the placebo than in patients in the propranolol

be measured:

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therefore,

is less important (4,5). so for varying reasons that 6 of this letter. That HVPG group who left the study group who left the study

partially explains the decrease in mean HVPG of the placebotreated patients who remained in the study. As stated in our report, no relationship was found between changes in HVPG and changes in variceal size during the study. Furthermore, we also document that a decrease in variceal size was found only in the group of patients in whom the HVPG decreased to < 12 mm Hg. At no time during the study was there a difference in variceal size between groups. Additional information about variceal size and its relationship to variceal bleeding is given in the clinical study (2). None of 21 patients whose HVPG levels decreased to < 12 mm Hg bled from varices. These 21 patients had a larger reduction in variceal size, a lower variceal hemorrhage incidence, and a lower mortality rate than the 63 patients in whom HVPG did not decrease to < 12 mm Hg. Twice as many patients treated with propranolol had HVPG decreased to < 12 mm Hg (14 propranololtreated vs. 7 placebo-treated patients). We do not claim that the beneficial effect of propranolol is due only to reductions in HVPG to < 12 mm Hg. In fact, this cannot be the case because propranolol was also protective of hemorrhage in patients in whom HVPG did not decrease to < 12 mm Hg. The mechanism by which propranolol is protective in this group of patients remains speculative. Because most of the bleeding occurred during the first year of therapy (10 of 11 bleeding episodes in the placebo group and 1 of 2 episodes in the propranolol group), propranolol seems to exert its protective effect during the period associated with the largest reduction in HVPG. It is not certain that these beneficial clinical effects are entirely attributable to a reduction in portal pressure. Experimental data suggest that the beneficial effect of propranolol is modulated by the combined decrease of portal flow and pressure induced by this agent (6). It could be argued that the beneficial effects observed in the group of patients with HVPG of < 12 mm Hg are the result of patient selection, i.e., a better risk group. In fact, this group of patients had a higher incidence of alcoholic liver disease but perhaps a greater chance of improvement following abstinence. This speculation, however, could not be proven. Of 20 alcoholics in the group, 7 (5 propranolol, 2 placebo) continued drinking, in spite of which HVPG decreased to