Effects of 1.32-μm Nd-YAG laser on brain thermal and histological experimental data

Considering that the 1.32-μm Nd-YAG laser should have physicothermal properties close to those of the CO₂ laser, a series of experiments were conducted on rat cortex (N = 51). Three laser wavelengths were compared: CO₂ laser (10.6 μm), 1.06-μm Nd-YAG, and 1.32-μm Nd-YAG lasers. For each shot, temperature measurements were recorded with an infrared thermographic videocamera. The digitized signals were figured as thermal profiles and temperature developments. Ninety-five shots were correctly studied and analyzed: CO₂, N = 29; 1.06-μm Nd-YAG, N = 20; 1.32-μm Nd-YAG, N = 46. The histological lesions produced by these three lasers were compared on animals killed 24 hours (N = 20), 8 days (N = 20), and 30 days (N = 5) after the laser impacts. For equivalent densities of energy, the depth of cortical necrosis was comparable for the CO₂ laser (200–250 μm) and the 1.32-μm Nd-YAG laser (210–260μm) whatever the date of death; the 1.06-μm Nd-YAG laser shots were responsible for much more important damage (400–550μm). Because of its important absorption in water and nervous tissue, the authors consider the 1.32-μm Nd-YAG laser most suitable for neurosurgery, particularly because it is conducted through optic fibers, and therefore is easy to handle during neurosurgical procedures.     

Nicardipine improves myocardial perfusion in systemic sclerosis

Primary scleroderma myocardial disease may be due in part to myocardial ischemia caused by a disturbance of the coronary microcirculation. We evaluated the effect of the calcium channel blocker nicardipine on myocardial perfusion assessed by thallium-201 scanning in 16 patients with systemic sclerosis. Thallium-201 single photon emission computerized tomography was performed at baseline and 90 min after 40 mg of oral nicardipine. The mean (+/- SD) number of left ventricular segments with perfusion defects significantly decreased from 6.0 +/- 2.0 at baseline to 4.1 +/- 2.3 after nicardipine (p less than 0.01). The mean global perfusion score significantly increased from 10.2 +/- 1.9 at baseline to 11.9 +/- 2.6 after nicardipine (p less than 0.02). Our study demonstrates short-term improvement in thallium-201 myocardial perfusion with nicardipine in patients with systemic sclerosis.     

Vécus psychologiques des démarches d'assistance médicale à la procréation

Assisted Reproductive Technologies (ART) come along with important emotional and psychological burden, as well as the physical constraints, for both the woman and her partner. Couples entering ART programs are usually infertile ones, but some specific settings, like serodiscordant couples where the male partner is HIV positive, involving fertile couples. These couples are usually well-adjusted and motivated ones. During the treatments, waiting for the outcome, and the unsuccessful cycles are among the most stressfull experiences. Common reactions are stress, anxiety and depression, but for some couples, the difficulties are so great that they discontinue the program after only one attempt. When parents, the couples usually experience good parenting competencies, and the “precious” children, despite a greater genetic risk, usually have a normal development, but some specific psychological difficulties may arise, that may request a specific help.     

Laser interstitial thermotherapy in stereotactical neurosurgery

The authors present their first experience with laser interstitial thermotherapy, (ITT). Four patients with deep-seated non-infiltrative benign tumours (three astrocytomas, one oligodendrocytoma) underwent ITT. Previously, a stereotactic procedure had been performed to determine the exact location of the tumour, its spatial configuration and its histological diagnosis. The MRI controls confirmed the efficacy of hyperthermia on the tumour tissues. The authors discuss the possible ITT mechanisms. The indications of such laser ITT in neurosurgery should be enlarged to malignant tumours (gliomas, metastases) and to certain hypophyseal adenomas.     

HIV-1 reactivation in resting peripheral blood mononuclear cells of infected adults upon in vitro CD4 cross-linking by ligands of the CDR2-loop in extracellular domain 1

HIV-1 infects resting peripheral blood mononuclear cells (PBMCs) but remains inactive state until subsequent cell activation. We have demonstrated that the cross-linking of cell surface CD4 by gp120-anti-gp120 immune complexes or heat-inactivated HIV-1 (iHIV-1) is sufficient to trigger activation signals leading to virus reactivation (9). In this study, we demonstrate that NF-kappaB nuclear translocation and stimulation of virus production by iHIV-1 were strictly linked to the concentrations of viral proteins used as exogenous stimuli. Moreover, we further investigated the physiologic relevance of these observations. When submitted to an in vitro CD4 cross-linking by iHIV-1, PBMCs from HIV-1-infected patients were found to produce virus. This viral reactivation was associated with increased NF-kappaB nuclear translocation in patients' PBMCs. Additionally, virus reactivation in resting PBMCs infected in vitro with HIV-1 was found to be specifically induced by ligands of the CDR2-loop in domain 1 (D1) of CD4 (virus envelope and anti-CD4 monoclonal antibodies). In contrast, virus reactivation was not observed following CD4 oligomerization by antibodies that bind other epitopes in D1, including the D1/CDR3-loop. Finally, soluble CD4 (sCD4) prevented virus reactivation by D1/CDR2-loop ligands. Our results indicate that the signaling events initiated in PBMCs by oligomerization of CD4 at the D1/CDR2-loop can trigger HIV-1 upregulation in infected individuals.     

Experimental and clinical standards,and evolution of lasers in neurosurgery

Summary From initial experiments of ruby, argon and CO₂ lasers on the nervous system so far, dramatic progress was made in delivery systems technology as well as in knowledge of laser-tissue interaction effects and hazards through various animal experiments and clinical experience. Most surgical effects of laser light on neural tissue and the central nervous system (CNS) are thermal lesions. Haemostasis, cutting and vaporization depend on laser emission parameters — wavelength, fluence and mode — and on the exposed tissues optical and thermal properties — water and haemoglobin content, thermal conductivity and specific heat. CO₂ and Nd-YAG lasers have today a large place in the neurosurgical armamentarium, while new laser sources such as high power diode lasers will have one in the near future. Current applications of these lasers derive from their respective characteristics, and include CNS tumour and vascular malformation surgery, and stereotactic neurosurgery. Intracranial, spinal cord and intra-orbital meningiomas are the best lesions for laser use for haemostasis, dissection and tissue vaporization. Resection of acoustic neuromas, pituitary tumours, spinal cord neuromas, intracerebral gliomas and metastases may also benefit from lasers as accurate, haemostatic, non-contact instruments which reduce surgical trauma to the brain and eloquent structures such as brain stem and cranial nerves. Coagulative lasers (1.06 m and 1.32 m Nd-YAG, argon, or diode laser) will find an application for arteriovenous malformations and cavernomas. Any fiberoptic-guided laser will find a use during stereotactic neurosurgical procedures, including image-guided resection of tumours and vascular malformations and endoscopie tumour resection and cysts or entry into a ventricle. Besides these routine applications of lasers, laser interstitial thermotherapy (LITT) and photodynamic therapy (PDT) of brain tumours are still in the experimental stage.The choice of a laser in a neurosurgical operating room implies an evaluation of the laser use (applications, frequency), of the available budget and costs-including purchase, maintenance and staff training-, and material that will be necessary: unit, peripherals, safety devices and measures, training programme.Future applications of lasers in neurosurgery will come from technological advances and refined experimental applications. The availability of new wavelength, tunable, small sized and smart laser units, will enlarge the thermal and non-thermal interactions between laser energy and neural tissue leading to new surgical applications. Tissue photo-ablation, photohynamic therapy using second generation of photosensitizers, updated thermotherapy protocols, are current trends for further use of lasers in neurosurgery.     

Quantitative variability in the biodistribution and in toxinokinetic studies of the three main alpha toxins from the Androctonus australis hector scorpion venom.

Scorpion stings represent a medical problem in numerous countries. The scorpion Androctonus australis hector produces three alpha toxins (Aah I to III), which are responsible for most of the lethality in mammals. These toxins act on sodium channel and do not cross-react immunologically. We used RIA and ELISA to measure the concentrations of these three toxins in plasma, urine and different organs after i.v. and s.c. injections of water extracts of venoms in rabbits or mice. In both animals, the toxins rapidly appeared in plasma after s.c. injection as it was previously described for the whole venom. However, the toxins disappeared from the blood more quickly than did other main components of the venom. Thus, serotherapy must be initiated immediately to prevent the toxin from reaching its target. We also detected the toxins in urine, kidneys, heart and lungs, but not in the brain. However, the concentration of Aah II was always lower than that of Aah I. Analysis of five samples of venom collected in different areas of southern Tunisia showed that a large polymorphism exists for the three toxins. This is yet another difficulty for serotherapy as there is no cross-antigenicity between them.