Enlarged meristems and delayed growth in plp mutants result from lack of CaaX prenyltransferases

Meristems require a myriad of intercellular signaling pathways for coordination of cell division within and between functional zones and clonal cell layers. This control of cell division ensures a constant availability of stem cells throughout the life span of the meristem while limiting overproliferation of meristematic cells and maintaining the meristem structure. We have undertaken a genetic screen to identify additional components of meristem signaling pathways. We identified pluripetala (plp) mutants based on their dramatically larger meristems and increased floral organ number. PLURIPETALA encodes the alpha-subunit shared between protein farnesyltransferase and protein geranylgeranyltransferase-I. plp mutants also have altered abscisic acid responses and overall much slower growth rate. plp is epistatic to mutations in the beta-subunit of farnesyltransferase and shows a synergistic interaction with clavata3 mutants. plp mutants lead to insights into the mechanism of meristem homeostasis and provide a unique in vivo system for studying the functional role of prenylation in eukaryotes.     

Laparoscopic cholecystectomy in the treatment of acute cholecystitis. Prospective non-randomized study

OBJECTIVES: To evaluate the results of laparoscopic cholecystectomy in patients with acute cholecystitis and to determine the optimal timing. PATIENTS AND METHODS: From January 1993 to December 1999, 168 patients (91 women and 77 men with a mean age of 57.3 years) underwent laparoscopic cholecystectomy for acute cholecystitis confirmed by histopathological examination. Patients were divided into 2 groups (similar in age and ASA classification): group 1 (106 patients) underwent laparoscopic cholecystectomy within 3 days after the onset of symptoms of acute cholecystitis and group 2 (62 patients) underwent laparoscopic cholecystectomy after 3 days. RESULTS: There was no death. Conversion rates were 30.9%. Surgery lasted 141.3 min, postoperative morbidity was 12.5%, and the postoperative length of hospital stay was 6.9 days. The conversion rates in patients who underwent surgery before and 3 days after the onset of symptoms were respectively 21.7% and 46.7% (P=0.0007). There was no statistical difference between early and delayed surgery for time to surgery and postoperative complications. On the other hand, the total hospital stay was significantly shorter in group 1. CONCLUSION: Laparoscopic cholecystectomy for acute cholecystitis is safe and associated with a shorter postoperative stay, a lesser morbidity and a lesser mortality compared to "open" surgery. Laparoscopic cholecystectomy should be carried out soon as the diagnostic of acute cholecystitis is established and preferably before 3 days after the onset of the symptoms. Early laparoscopic cholecystectomy allows a reduction of the conversion rate and a reduction of total hospital stay that are medical and economic benefits.     

Are the results of electrophysiological study different in patients with a pre-excitation syndrome, with and without syncope?

AIMS: Syncope in Wolff-Parkinson-White (WPW) syndrome may reveal an arrhythmic event or is not WPW syndrome related. The aim of the study is to evaluate the results of electrophysiological study in WPW syndrome according to the presence or not of syncope and the possible causes of syncope. METHODS AND RESULTS: Among 518 consecutive patients with diagnosis of WPW syndrome, 71 patients, mean age 34.5 +/- 17, presented syncope. Transoesophageal electrophysiological study in control state and after isoproterenol infusion was performed in the out-patient clinic. Atrioventricular re-entrant tachycardia (AVRT) was more frequently induced than in asymptomatic patients (n = 38, 53.5%, P < 0.01), less frequently than in those with tachycardia; atrial fibrillation (AF) and/or antidromic tachycardia (ATD) was induced in 28 patients (39%) more frequently (P < 0.05) than in asymptomatic patients or those with tachycardia. The incidence of high-risk form [rapid conduction over accessory pathway (AP) and AF or ATD induction] was higher in syncope group (n = 18, 25%, P < 0.001) than in asymptomatic subjects (8%) or those with tachycardias (7.5%). Maximal rate conducted over AP was similar in patients with and without syncope, and higher in patients with spontaneous AF, but without syncope. Results were not age-related. CONCLUSION: Tachycardia inducibility was higher in patients with syncope than in the asymptomatic group. The incidence of malignant WPW syndrome was higher in patients with syncope than in asymptomatic or symptomatic population, but the maximal rate conducted over AP was not higher and another mechanism could be also implicated in the mechanism of syncope.