Cyclin-dependent kinase inhibitors p21 and p27 function as critical regulators of liver regeneration following 90% hepatectomy in the rat

BACKGROUNDLiver reduction is the main curative treatment for primary liver cancer, but its use remains limited as liver regeneration requires a minimum of 30% functional parenchyma. AIMTo study the dynamics of the liver regeneration process and consequent behavior of cell cycle regulators in rats after extended hepatectomy (90%) and postoperative glucose infusions.METHODSPost-hepatectomy liver failure was triggered in 84 Wistar rats by reducing their liver mass by 90%. The animals received a post-operative glucose infusion and were randomly assigned to two groups: One to investigate the survival rate and the other for biochemical analyses. Animals that underwent laparotomy or 70% hepatectomy were used as controls. Blood and liver samples were collected on postoperative days 1 to 7. Liver morphology, function, and regeneration were studied with histology, immunohistochemistry, and western blotting. RESULTSPostoperative mortality after major resection reached 20% and 55% in the first 24 h and 48 h, respectively, with an overall total of 70% 7 d after surgery. No apparent signs of apoptotic cell death were detected in the extended hepatectomy rat livers, but hepatocytes displaying a clear cytoplasm and an accumulation of hyaline material testified to changes affecting their functional activities. Liver regeneration started properly, as early events initiating cell proliferation occurred within the first 3 h, and the G1 to S transition was detected in less than 12 h. However, a rise in p27 (Kip1) followed by p21 (Waf1/Cip1) cell cycle inhibitor levels led to a delayed S phase progression and mitosis. Overall, liver regeneration in rats with a 90% hepatectomy was delayed by 24 h and associated with a delayed onset and lower peak magnitude of hepatocellular deoxyribonucleic acid synthesis. CONCLUSIONThis work highlights the critical importance of the cyclin/cyclin-dependent kinase inhibitors of the Cip/Kip family in regulating the liver regeneration timeline following extended hepatectomy.     

Enhanced polymerization of recombinant human deoxyhemoglobin beta 6 Glu----Ile.

Polymerization of the deoxy form of sickle cell hemoglobin (Hb S; beta 6 Glu----Val) involves both hydrophobic and electrostatic intermolecular contacts. These interactions drive the mutated molecules into long fibrous rods composed of seven pairs of strands. X-ray crystallography of Hb S and electron microscopy image reconstruction of the fibers have revealed the remarkable complementarity between one of the beta 6 valines of each molecule (the donor site) and an acceptor site at the EF corner of a neighboring tetramer. This interaction constitutes the major lateral contact between the two strands in a pair. To estimate the relative importance of this key hydrophobic contact in polymer formation we have generated a polymerizing Hb with isoleucine at the beta 6 position (beta E6I) by site-directed mutagenesis. The mutated beta chains were produced in Escherichia coli and reassembled into functional tetramers with native alpha chains. Compared to native Hb S, the beta E6I mutant polymerizes faster and with a shortened delay time in 1.8 M phosphate buffer, indicating an increased stability of the nuclei preceding fiber growth. The solubility of the beta E6I mutant Hb is half that of native Hb S. Computer modeling of the donor-acceptor interaction shows that the presence of an isoleucine side chain at the donor site induces increased contacts with the receptor site and an increased buried surface area, in agreement with the higher hydrophobicity of the isoleucine residue. The agreement between the predicted and experimental differences in solubility suggests that the transfer of the beta 6 valine or isoleucine side chain from water to a hydrophobic environment is sufficient to explain the observations.     

Modified radical vaginal hysterectomy with or without laparoscopic nerve-sparing dissection: a comparative study

OBJECTIVE: Nerve-sparing dissection of the lateral portion of the cardinal ligament (paracervical lymphadenectomy) has been recently developed with the goal of reducing the late urinary adverse effects of radical hysterectomy without impairing the outcome. This work has been carried out in order to investigate the influence of additional paracervical lymph node dissection at the time of laparoscopically assisted modified radical hysterectomy on outcome and urinary sequelae. METHODS: A total of 95 patients underwent a modified radical hysterectomy using a combined laparoscopic and vaginal approach since 1991. In 47 of these patients treated since 1996 an additional laparoscopic paracervical lymphadenectomy was performed. The operative, postoperative, and survival outcomes were assessed. In 60 patients, 32 and 28 in the groups of patients with or without paracervical dissection, respectively, a careful interview on urinary symptoms was conducted by an independent investigator. RESULTS: Paracervical dissection involves no operative complication and lenghthens the postoperative urinary retention, but has no adverse influence on long-term urinary discomfort. The yield of paracervical dissection is negligible for small tumors: no positive node was found in 38 patients with tumors less than 2 cm in diameter. The outcome of patients after minimal access surgery for tumors less than 2 cm is excellent whether or not a paracervical dissection has been performed. CONCLUSION: Paracervical dissection does not worsen the late urinary symptoms after vaginal radical hysterectomy. It has a limited value in the surgical management of small-size (less than 2 cm) cervical cancers, although it may prevent long-term lateropelvic recurrences.     

Évaluations prédictives de l’entorse de cheville. À propos de 58 cas

When an injury comes out, it is seen like a fatality for a sportsman and the medical staff. The ankle sprain is from far the most common pathology. Preventions programs proved their efficiency in many fields. However, it is very hard to put them into practice because there is few or no tools to these persons. The goal of this work is to provide assessments reliable, reproducible and non-dependent operator that will identify potential topics victim of a sprain ankle in the medium term. We tested 58 youngs healthy athletes whose sport practice was up to 2 hours a week. We have made assessments on a motor coordination machine, on a posturography platform and we analysed the muscular benefits of each lower limbs thanks to a accelerometer. These analyses have been done in November 2007, January 2008 and March 2008. We sorted out five articulars instability. Topics victims of the ankle sprain during the study got a 13% coordination deficiency. The difference is statisticly significant. All the tests which have been done on the postuography plateform were not accepted because the evaluation results were not comparables with the 1985 norms of the French Association of Posturology. We were able to see a curve problem with wounded patients during the ground absorbtion phase and had a stabilisation time shorter than the one for the healthy subjects. This significative difference was up to 110 ms. Pope et al. find out on patients hit by a talocrural sprain, a significative diminution of the dorsiflexion during the previous traumatism report. Willems et al. find these facts and describe others intrinsic factors of predisposition which match our results. Our work proved that it is possible to warn, in a mid term, the sprain of the ankle. These warnings reports must be done in the beginning of the sporting season and will allow to determine the athletes weakness thanks to reliable and reproducible evaluations.     

Studies on the megakaryocytes of a patient with the Bernard-Soulier syndrome

We have used monoclonal antibodies AP-1 (anti-GP Ib alpha). AP-2 (anti-GP IIb-IIIa) and FMC 25 (anti-GP IX) in immunofluorescence and immunocytochemical studies on megakaryocytes (MK) isolated from a Bernard-Soulier syndrome (BSS) patient whose giant platelets were characteristically deficient in GP Ib-IX complexes. Electron microscopy showed that the patient's MK were similar in size to normal MK. However, a striking feature was the variable and intermittent nature of the demarcation membrane system which was often vacuolar in appearance. Permeabilized mature MK from normal individuals were strongly positive with AP-2, AP-1 and FMC 25. Those from the BSS patient were normal for AP-2, negative for AP-1 but weakly positive with FMC 25. Binding of the monoclonal antibodies to the patient's platelets was evaluated using flow cytometry. The results confirmed the absence of GP Ib alpha from the surface membranes, but showed the presence of small amounts of GP IX distributed throughout the platelet population. Our findings confirm that the membrane lesion in BSS is also to be found in MK and further show that the defect may affect differently individual constituents of the GP-Ib-IX complex.