Tissular and mechanical effects observed with an experimental femtosecond laser microkeratome for corneal refractive surgery

PURPOSE: Despite progress in mechanical microkeratomes used in refractive surgery, mechanical complications during cutting of the cornea still occur. Cutting by laser could reduce these complications and to date, the femtosecond laser is the only potential candidate for this purpose. Our study reports preliminary results with a femtosecond microkeratome for cutting porcine corneas ex vivo. METHODS: We first examined the fundamental principles of the interaction between the femtosecond laser and the corneal stroma, including the volume of tissue lesions, the laser breakdown threshold of the stroma and the laser ablation selectivity. We then analyzed the quality of cutting corneal flaps with the laser, focusing on collateral tissue effects and the roughness of the interfaces observed both histologically and with scanning electron microscopy. RESULTS: The photoablative and photodisruptive effects were very similar with the femtosecond laser. This characteristic is specific to ultrashort impulsion photodisruptor lasers and allows for a very precise surgical procedure. The laser-induced breakdown threshold of porcine corneal stroma was found to be 0.55 J/cm2. Collateral tissue lesions were on the submicrometer level. The roughness of the stromal bed was optimal for postage stamp cutting, providing very many contiguous points of impact which were as spherical as possible. CONCLUSION: Corneal photodisruption with a femtosecond laser is reproducible and extremely accurate. The optomechanical parameters involved with this technique require great technological skill and should be placed in experienced hands.     

Cortical Regulation of Striatal Neuropeptide Y (NPY)-Containing Neurons in the Rat

This study examined the functional relationships established by nigral, cortical, and thalamic striatal afferent pathways with neuropeptide Y (NPY)-containing neurons in the rat rostral striatum by coupling selective deafferentation procedures and NPY immunohistochemistry. Previous experiments have shown that after unilateral 6-hydroxydopamine (6-OHDA)-induced degeneration of nigrostriatal dopaminergic neurons, the mean number of NPY-immunoreactive (Ir) neurons per frontal section was increased in the striatum ipsilateral to the lesion side and unaltered in the contralateral striatum. The present topographical analysis of the 6-OHDA lesion effects led us to state that the increase in NPY-Ir neuron density occurs in restricted ventral and medial zones of the ipsilateral striatum. Unilateral ablation of the frontoparietal cerebral cortex by thermocoagulation was moreover shown to elicit, 20 - 30 days later, a significant bilateral increase in the number of striatal NPY-Ir cells. The increase was more marked in the striatum ipsilateral to the hemidecortication where it was similar in amplitude to that induced by the 6-OHDA lesion. The topographical analysis of the cortical lesion effects also revealed an uneven striatal response, but, in contrast to that observed for the 6-OHDA lesion, changes were restricted to dorsolateral areas of the striatum in both brain sides, revealing an apparent complementarity of nigral dopaminergic and cortical influences over striatal NPY neuronal system. Combined unilateral nigral and cortical lesions surprisingly counteracted in a survival time dependent manner the effects of each lesion considered separately. In that condition topographical changes related to the 6-OHDA lesion totally disappeared and those related to the cortical lesion were attenuated but still present. These results suggest that expression of striatal dopamine - NPY interaction is dependent on corticostriatal transmission. Interestingly lesion of thalamic areas projecting to the striatum did not significantly modify the mean number of NPY-Ir neurons determined per section from the whole striatal surface, but selectively increased the NPY neuron density in the mediodorsal region of the striatum, suggesting that the striatal NPY-containing neuronal system is also influenced by thalamostriatal projections.     

New group of class III antiarrhythmic drugs: piperid-4-ylethane derivatives

A series of new piperid-4-ylethane derivatives possessing antiarrhythmic activity has been synthesized and studied. The most active compound, 1-(4-fluorophenyl)-1-(4-nitrobenzoylamino)-2-(N-ethylpiperid-4-yl)ethane (niferidyl) hydrochloride, was selected for clinical trials as a potential class III antiarrhythmic drug.     

A potential combined formulation containing vinpocetin and succinic acid

Succinic acid bas been found to be able to potentiate the antihypoxic activity of vinpocetin. This property (potentiation) provided grounds for creating a new combined formulation containing vinpocetin and succinic acid, which has more marked antihypoxic activity than the initial single-substance vinpocetin formulation, along with antiamnestic and anticonvulsive activities.     

Monitoring hémodynamique non invasif chez l’enfant

Circulatory failure is an important cause of pediatric morbidity and mortality and requires early recognition and prompt treatment with adequate protocols. Advanced hemodynamic monitoring consists in the non-invasive measurement of cardiac output and predictive parameters of fluid responsiveness. Here, we discuss the interest of hemodynamic monitoring devices in relation to pediatric physiology.     

Clinical trial of a leucotriene B4 receptor antagonist, BIIL 284, in patients with rheumatoid arthritis

BACKGROUND: Several clinical and experimental lines of evidence suggest that leucotriene B4 (LTB4), an arachidonic acid derivative with potent proinflammatory properties, plays a key role in the pathophysiology of rheumatoid arthritis (RA). OBJECTIVE: To evaluate the efficacy and safety of BIIL 284, an oral long-acting LTB4 receptor antagonist, as monotherapy for the treatment of patients with active RA. METHODS: This was a multi-centre, randomised, double-blind, placebo-controlled trial of patients with active RA of 3 months' duration. A total of 342 patients were randomised to receive 5 mg, 25 mg or 75 mg of BIIL 284 or placebo. The primary end point was the percentage of patients achieving an American College of Rheumatology (ACR) 20. RESULTS: Although a higher percentage of ACR 20 responders was observed in the groups treated with 25 mg and 75 mg of BIIL 284 compared with those treated with placebo, no statistically significant differences were found between any of the three active treatment groups compared with the placebo group with regard to the primary or secondary end points. All trial treatments were safe and well tolerated. CONCLUSIONS: This clinical trial demonstrates that treatment of patients with active RA with a potent oral long-acting LTB4 receptor antagonist produced only modest improvements in disease activity. The results of this trial support the conclusion that LTB4 is not a major contributor to the inflammatory process in RA.     

Randomized trial of the triple monoamine reuptake inhibitor NS 2330 (tesofensine) in early Parkinson's disease.

The objective of this study was to evaluate the efficacy and safety of three daily dosages of the triple monoamine reuptake inhibitor NS 2330 (tesofensine) compared to placebo as monotherapy in early Parkinson's disease (PD). In MPTP (1-methyl 4-phenyl-tetrahydropyridine 1,2,3,6)-lesioned marmosets, dopamine reuptake inhibitors have been demonstrated to reverse parkinsonian signs without evoking established dyskinesia. NS 2330 inhibits reuptake of dopamine, serotonin, and norepinephrine. We performed a proof-of-concept, randomized, double-blind trial of NS 2330. Two hundred sixty-one subjects with PD < 5 years and not receiving dopaminergic treatment were randomly assigned to daily treatment with NS 2330 at 0.25 mg, 0.5 mg, 1.0 mg, or placebo. Adjusted mean difference in total Unified Parkinson's Disease Rating Scale (UPDRS) scores from baseline to week 14 was -0.7 (P = 0.64) in the 0.25-mg group, -1.3 (P = 0.41) in the 0.5-mg group, and -1.7 (P = 0.27) in the 1.0-mg group. The adjusted mean difference in total UPDRS score for the highest dose group (1.0 mg/day) was superior to placebo at week 6 (-3.1; P = 0.02), but this effect was not sustained. NS 2330 was generally well tolerated and the most commonly reported adverse events were constipation, insomnia, and dry mouth. Decreased body weight and elevated heart rate were common in the 1.0-mg dosage group. At the dosages tested, NS 2330 did not provide significantly greater benefit than placebo. It is possible that inhibition of dopamine reuptake alone does not provide clinical benefit in early PD, adequate inhibition of dopamine reuptake was not achieved in this study, or countervailing physiologic mechanisms offset the potential benefit.