First experiences with a 2.0-μm near infrared laser system for neuroendoscopy

Nd:YAG, argon and diode lasers have been used in neurosurgical procedures including neuroendoscopy. However, many neurosurgeons are reluctant to use these lasers because of their inappropriate wavelength and uncontrollable tissue interaction, which has the potential to cause serious complications. Recently, a 2.0-microm near infrared laser with adequate wavelength and minimal tissue penetration became available. This laser was developed for endoscopic neurosurgical procedures. It is the aim of the study to report the initial experiences with this laser in neuroendoscopic procedures. We have performed 43 laser-assisted neuroendoscopic procedures [multicompartmental congenital, posthaemorrhagic or postinfectious hydrocephalus (n = 17), tumour biopsies (n = 6), rescue of fixed and allocated ventricular catheters (n = 2), endoscopic third ventriculostomy (ETV, n = 17) and aqueductoplasty (n = 1)] in 41 patients aged between 3 months and 80 years. The laser beam was delivered through a 365-microm bare silica fibre introduced through the working channel of a rigid endoscope. It was used for the opening of cysts, perforating the third ventricular floor, and for coagulation prior to and after biopsy. The therapeutic goals [creating unhindered cerebrospinal fluid (CSF) flow between cysts, ventricles and cisterns, sufficient tissue samples for histopathological diagnosis and catheter rescue] were achieved in 40 patients by the first and in 2 patients by a second neuroendoscopic operation. In one child, a CSF shunt was later required despite patency of the created stoma proven by magnetic resonance imaging (MRI). In another patient ETV was abandoned due to a tiny third ventricle. There was neither mortality nor transient or permanent morbidity. The authors conclude that the use of the 2.0-microm near infrared laser enables safe and effective procedures in neuroendoscopy.

Expression of the fibroblast growth factor 4 (FGF-4) gene is regulated by serum in Tera-2 embryonal carcinoma cells

Expression of the fibroblast growth factor 4 (FGF-4) gene is tightly regulated during mammalian development. Dysregulation of FGF-4 gene expression results in cell transformation and tumorigenesis. It is therefore pertinent to investigate the regulatory mechanisms which control expression of FGF-4. In an initial attempt to identify exogenous factors other than retinoic acid which might control FGF-4 expression, we have investigated the response of endogenous FGF-4 to serum in a number of embryonal carcinoma and embryonic stem cell lines. We have identified a human embryonal carcinoma cell line (Tera-2) in which the FGF-4 gene can be induced by serum. In Tera-2 cells made quiescent by serum deprivation, expression of the FGF-4 gene is repressed. Subsequent addition of serum reactivates FGF-LC expression and further addition of cycloheximide results in superinduction of mRNA suggesting that FGF-4 may be classified as an early response gene. It is suggested that this observation may be explained, at least in part, by the stage of differentiation of the Tera-2 cells.