Human telomerase is regulated by erythropoietin and transforming growth factor-beta in human erythroid progenitor cells.

Telomerase catalytic subunit (hTERT) exerts important cellular functions including telomere homeostasis, genetic stability, cell survival and perhaps differentiation. However, the nature of external or internal signals, which regulate hTERT expression in tissues, remains poorly understood. Thus, whereas it has been described that hTERT gene is regulated along the differentiation of primitive myeloid progenitors, the effect of specific cytokines on telomerase expression in each myeloid lineage is currently unknown. Based on these considerations, we have investigated hTERT expression in erythroid cells treated with erythropoietin (EPO) and transforming growth factor beta (TGFbeta), as putative positive and negative regulators, respectively. We describe here that EPO activates hTERT gene transcription in in vitro-expanded primary erythroid precursors as well as in UT7 erythroleukemia cells. In UT7 cells, this study shows also that EPO acts through a JAK2/STAT5/c-myc axis. In contrast, TGFbeta blocks EPO signaling downstream of c-myc induction through a Smad3-dependent mechanism. Finally, hTERT appears to be efficiently regulated by EPO and TGFbeta in an opposite way in erythropoietic cells, arguing for a role of telomerase in red blood cell production.

[Multimodal monitoring of head injuries in children]. / Monitorage multimodal chez l'enfant traumatisé crânien.

As in the case of adults, there are three main goals in the monitoring of severe head trauma in children: to prevent or minimize the apparition of secondary lesions, to optimize treatment, to help make precise prognosis. The basic monitoring is composed of repeated clinical examinations, brain radiological imaging and control of vital parameters (blood pressure, temperature, PaO2 (SpO2), PaCO2 (FETCO2), haemoglobin, haematocrit. On the other hand, during specific brain monitoring, the brain perfusion (TCD, intracranial pressure), the electrical activity of the brain and sometimes the brain oxygenation (SvjO2) are controlled. The data obtained from the brain monitoring must always be interpreted carefully. A child with a severe head trauma, in ICU, always requires constant and competent medical attention.

[Evaluation of transfusion strategies during craniosynostosis repairs]. / Evaluation de la stratégie transfusionnelle au cours des craniosténoses.

OBJECTIVE: To evaluate the changes in transfusion practices during craniosynostosis surgery in children, with consideration of the transfusion-associated risks. STUDY DESIGN: Retrospective study. PATIENTS: The study included 64 consecutive craniosynostosis repairs by the same neurosurgical and anaesthetic team, over a period of 17 years. METHODS: The children were allocated into two groups. In group I (1980-1991), blood loss was compensated precisely from scalp incision on. In group II (1992-1996), transfusion was only started when blood loss crossed a calculated limit considered as acceptable. The mean criterion of judgment was the quantity of transfused blood in comparison with the theoretical blood volume. Mean preoperative and postoperative haemoglobin concentrations, estimated blood losses, volume of replaced blood and number of transfused patients were compared between the two groups with a two tailed Student's t test. RESULTS: The rate of non transfused children increased from 6% before 1991 to 39% after 1992%; conservely the rate of postoperative transfusions increased from 3 to 39%. CONCLUSION: The risks of blood transfusion favoured the development of new of more restrictive transfusion practices, even in haemorrhagic surgery. To limit blood transfusion in craniosynostosis surgery, a harmonious cooperation between surgeons and anaesthetists is essential and blood replacement must be based on a definite determination of the acceptable blood losses.

[Infection after long lasting procedure in neurosurgery]. / Infection après intervention de longue durée en neurochirurgie.

A retrospective study was performed to appreciate the frequency of infectious complications following long duration neurosurgical procedure with or without antibiotic prophylaxis. Among the 6,702 surgical procedures studied 87 lasted more than 6 hours. The frequency of wound infections of those 87 patients was 13.8% whereas it was only 1.43% for the whole group. There was no significant statistical difference between patients who were treated with antibiotics and those who were not. The high frequency of infection by Klebsiella (25% of the identified germs) was caused by a contamination of the intensive care unit. Duration of the surgical procedure, synthetic material and repetitive procedures are important points to analyse when comparing the different publications. If any antibiotic prophylaxis is to be used, it must be adapted to the microbial environment of each care unit.

[Are calcium channel blockers really useful in cerebral aneurysm surgery?]. / Les anticalciques sont-ils réellement utiles en chirurgie anévrysmale cérébrale?

Two retrospective series of early operated cerebral arterial aneurysms are compared. One series involves 74 patients treated from 1983 to 1987 by vascular volume expansion only. The other series involves 75 patients treated from 1987 to 1990 by vascular volume expansion associated by calcium antagonists (nimodipine or nicardipine). The conclusion is that in our experience, calcium antagonists do not improve the outcome (mortality, cognition findings and return to work) obtained by vascular volume expansion alone. Moreover they put forward that there is no difference between the patients treated by nimodipine and those treated by nicardipine.