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Languages across the world exhibit Zipf's law of abbreviation, namely more frequent words tend to be shorter. The generalized version of the law - an inverse relationship between the frequency of a unit and its magnitude - holds also for the behaviours of other species and the genetic code. The apparent universality of this pattern in human language and its ubiquity in other domains calls for a theoretical understanding of its origins. To this end, we generalize the information theoretic concept of mean code length as a mean energetic cost function over the probability and the magnitude of the types of the repertoire. We show that the minimization of that cost function and a negative correlation between probability and the magnitude of types are intimately related., Comment: New results for optimal non-singular coding have been added; some sections have been reorganized

Cardiac dysfunction following brain death is associated with highly increased myocardial norepinephrine, lactate and adenosine concentrations. Administration of labetalol, a mixed alpha-, beta-adrenergic receptor antagonist, attenuates metabolic disturbances and improves myocardial function. The purpose of this study was to investigate beta-adrenergic receptor (beta AR) density and affinity in the presence or absence of labetalol administration, as a possible mechanism of the protective effects of this drug.Experimental animals were divided into three groups: sham-operated, brain-dead pigs, and brain-dead pigs treated with labetalol (10 +/- 3 mg/kg). The maximum number of binding sites (Bmax) and the dissociation constant (Kd) of beta AR were determined with (-)-[125I]cyanopindolol on myocardial samples harvested 3 hours after brain death.Left ventricular beta AR density and affinity were identical in brain-dead and sham-operated animals. Labetalol-treated pigs exhibited a significant decrease of Bmax and an increase of Kd as compared with brain-dead pigs. Bmax decrease was due to the persistence of labetalol in the membrane preparations. Increased Kd was too low to be biologically significant. Therefore, beta AR number and affinity can be considered as unchanged after adrenergic blockade with labetalol.The protective mechanism of labetalol on brain death-induced myocardial dysfunction cannot be explained by changes in beta AR density and affinity but is probably related to a preservation of the oxygen consumption/oxygen delivery balance during the autonomic storm.

This is the evaluation of the feasibility and results of routine laparoscopic intraoperative cholangiography.A multicentric prospective study in 315 consecutive patients undergoing elective or urgent laparoscopic cholecystectomy.The success rate was 94%. Mean duration of intraoperative cholangiography was 12 min. Sixteen of 18 failures were related to a narrow cystic duct. One cystic duct avulsion (ligated under laparoscopy) and 2 false positive cholangiograms (1 transcystic exploration, 1 conversion) were noted. Intraoperative cholangiography revealed aberrant bile ducts possibly at risk to injury from dissection in four patients (1.3 per cent). Intraoperative cholangiography disclosed unsuspected stones in 10 patients (4%). Forty-five patients had a preoperative suspicion of choledocholithiasis: choledocholithiasis were found at intraoperative cholangiography in 3 of 13 patients who had preoperative endoscopic sphincterotomy for stone extraction, in 1 of 11 patients with normal preoperative endoscopic cholangiography, and in 11 of 21 patients undergoing surgery alone (57%).If complete clearance of choledocholithiasis is to remain the objective of surgical treatment of biliary lithiasis including laparoscopic cholecystectomy, then routine intraoperative cholangiography is feasible and efficient.

Evaluation of the feasibility and results of the one-stage treatment combining routine intraoperative cholangiography and laparoscopic common bile duct exploration for choledocholithiasis.Multicentric (5 centers-9 surgeons) prospective study in 247 consecutive patients (mean age 68 years; range 21-92) during a 50-month period (November 1991-December 1995). Laparoscopic treatment of choledocholithiasis was attempted irrespective of the circumstances leading to the diagnosis of biliary lithiasis or the preoperative suspicion of choledocholithiasis.One out of four patients (n = 61) had unsuspected choledocholithiasis disclosed by routine intraoperative cholangiography. A laparoscopic complete clearance of choledocholithiasis was achieved in 208 of 236 attempted cases (88%), with either transcystic duct extraction (n = 116) or choledochotomy (n = 92). Open surgery was required in 20 patients for failure of laparoscopic treatment and in 3 patients despite successful extraction. Twenty-one of 25 patients (84%) referred for failure of retrograde endoscopic stone extraction had successful laparoscopic choledocholithiasis clearance. The mean duration for the laparoscopic transcystic approach and choledochotomy were 108 min (range 50-300) and 173 min (range 70-480), respectively. Eleven patients had retained stones (4.4%). Minor and major complications were recorded in 9 and 22 patients respectively. The operative mortality was 0.4% (95% confidence interval: 0-1.2%).Intraoperative cholangiography during laparoscopic cholecystectomy and laparoscopic common bile duct exploration when required should be considered as the simplest and most efficient treatment for choledocholithiasis. The multicenter character of this study including consecutive patients from public and private practices, strengthens our conclusions and is consistent with a wide diffusion of this diagnostic and therapeutic strategy.

The aim of this study was to assess the feasibility and results of common bile duct laparoscopic treatment and exploration in patients with choledocholithiasis.From November 1991 to December 1994, 189 consecutive malades (120 females; mean age 68 years, range: 21-92) with choledocholithiasis identified during routine intraoperative cholangiogram underwent surgical exploration of common bile duct in 5 surgical centers. Twenty patients were referred to surgery after unsuccessful endoscopic sphincterotomy.Following laparoscopic exploration and intraoperative cholangiography, common bile duct stone extraction by laparoscopy was not attempted in 11 patients (5.8%). The common bile duct was successfully cleared of all stones in 153 patients (81% of the overall population and 86% of laparoscopic attempts), either via the transcystic route (n = 97) or through choledocotomy (n = 56). Eighteen patients required conversion to open surgery, 16 for unsuccessful stone extraction and 2 despite successful stone extraction. Postoperative endoscopic sphincterotomy was required in 7 patients (4.4%) for retained stones after laparoscopic treatment. There were no postoperative deaths (95% confidence interval 0-1.6%), and follow-up, ranging from 3 to 42 months, has shown no further clinical evidence of retained stones.Diagnosis and treatment of common bile duct stones is feasible by laparoscopy, and the results in this series compare favorably with those of conventional surgical treatment. Complete treatment of biliary lithiasis, in one operation, avoids the pitfalls of patient selection for preoperative endoscopic retrograde cholangiography and the risks of endoscopic sphincterotomy.