Study of graphene dispersions in sodium dodecylsulfate by steady-state fluorescence of pyrene.

HYPOTHESIS: Aqueous solutions of ionic surfactants allow the exfoliation of graphene, that can be explained considering the adsorption model of ionic surfactants to hydrophobic surfaces. For many years, pyrene has been used as a fluorescent probe because its sensitivity to the micro-environment. The study of pyrene fluorescence in the presence of different graphene dispersions in an ionic surfactant, would improve the knowledge of the graphene-surfactant interactions. EXPERIMENTS: Different dispersions of graphene in sodium dodecylsulfate were prepared at different weight ratios 0.5, 1 and 2%. The dispersions have been studied by Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The influence of the dispersions on the pyrene fluorescence has been investigated. FINDINGS: The graphene sheets modified by the surfactant quench the fluorescence of pyrene, which depends on the amount of graphene, the concentration of surfactant and the weight ratio. For surfactant concentrations below the critical micelle concentration, the quenching effect is higher as the weight ratio increases. Once this concentration is reached, the fluorescence increases slightly and then levels off. This behavior has been explained by the adsorption model. For a constant surfactant concentration, two straight lines can be observed in the Stern-Volmer plots whose cut-off point is approximately 20 mg L-1 of graphene.

The influence of a compatibilizer on the thermal and dynamic mechanical properties of PEEK/carbon nanotube composites.

The effect of polyetherimide (PEI) as a compatibilizing agent on the morphology, thermal, electrical and dynamic mechanical properties of poly(ether ether ketone) (PEEK)/single-walled carbon nanotube (SWCNT) nanocomposites, has been investigated for different CNT loadings. After a pre-processing step based on ball milling and pre-mixing under mechanical treatment in ethanol, the samples were prepared by melt extrusion. A more homogeneous distribution of the CNTs throughout the matrix is found for composites containing PEI, as revealed by scanning electron microscopy. Thermogravimetric analysis demonstrates an increase in the matrix degradation temperatures under dry air and nitrogen atmospheres with the addition of SWCNTs; the level of thermal stability of these nanocomposites is maintained when PEI is incorporated. Both differential scanning calorimetry and synchrotron x-ray scattering studies indicate a slight decrease in the crystallization temperatures of the compatibilized samples, and suggest the existence of reorganization phenomena during the heating, which are favoured in the composites incorporating the compatibilizer, due to their smaller crystal size. Dynamic mechanical studies show an increase in the glass transition temperature of the nanocomposites upon the addition of PEI. Furthermore, the presence of PEI causes an enhancement in the storage modulus, and hence in the rigidity of these systems, attributed to an improved interfacial adhesion between the reinforcement and the matrix. The electrical and thermal conductivities of these composites decrease with the incorporation of PEI. Overall, the compatibilized samples exhibit improved properties and are promising for their use in industrial applications.

Effect of relapses over early progression of disability in multiple sclerosis patients treated with beta-interferon.

Observational study designed to explore the effect of demographical variables and number of relapses over the disability progression in the two first years of beta-interferon treatment for multiple sclerosis. One hundred and sixty two patients treated with beta-interferon for at least two years were included, 70.9% females, mean age 33.4 years, mean disease duration 75.1 months, mean EDSS 2.4, previous year relapse rate 1.3. Main end-point was defined as a sustained EDSS increase (1.5 if previous EDSS 0-2.0; 1.0 if previous EDSS 2.5-4.0; 0.5 if previous EDSS 4.5 or higher). 62.3% of patients presented one or more relapses and 32.7% patients reached sustained disability increase. The univariate and multivariate Cox regression analysis only showed statistical significance for the relapses in the two first years after the treatment (HR 1 relapse: 3.4, p = 0.05; HR > or = 2 relapses: 4.3, p < 0.001). The Kaplan-Meier survival analysis showed a higher probability of EDSS progression for patients with one relapse (log rank 10.9, p = 0.02) and with > or = 2 relapses (log rank 17.7, p < 0.001), with no differences between them (p = 0.38). In conclusion, patients with one or more relapses in the first two years of interferon treatment developed an earlier sustained progression of the disability.

Evaluation of response of multiple sclerosis (MS) relapse to oral high-dose methylprednisolone: usefulness of MS functional composite and Expanded Disability Status Scale.

To compare the usefulness of multiple sclerosis functional composite (MSFC) to the Expanded Disability Status Scale (EDSS) in assessing functional changes related to relapse. A prospective 12-week follow-up study after relapse was conducted among 14 multiple sclerosis (MS) patients treated with oral high-dose (1 g) methylprednisolone for 3 days. MSFC and the EDSS were assessed on day 0, before treatment and, 1, 4 and 12 weeks afterwards. In relapses, EDSS (2.5 +/- 1.2 to 3.8 +/- 1.0) and z-score of the MSFC (0.15 +/- 0.58 to -0.59 +/- 0.70) worsened. After 1 week of treatment, the EDSS improved (3.3 +/- 1.2; P = 0.002) while the MSFC did not change significantly. At week 4, EDSS improvement was maximal (2.8 +/- 1.3; P = 0.001). At week 12, EDSS remained stable whereas z-score continued improving (0.26 +/- 0.74). z-9peg-hole-test was the most sensitive subtest. There was correlation between baseline values of both scales (-0.620, P < 0.05) and between changes due to relapse (-0.535, P < 0.05). 78.5% of patients had improved at week 4 (35.7% at week 1). There were no serious adverse effects. MSFC and the EDSS were sensitive to changes due to relapses, although the dynamics for restoring baseline function were different. Our data support the usefulness of both scales in clinical trials, providing complementary information about outcome of MS patients with relapses.

[Prospective assessment of the treatment of multiple sclerosis relapses with oral high-dose methylprednisolone: response and tolerability data]. / Evaluación prospectiva del tratamiento de brotes de esclerosis múltiple con megadosis oral de metilprednisolona: datos de respuesta y seguridad.

OBJECTIVE: This study aims to assess the response and safety of the treatment of multiple sclerosis (MS) episodes with high oral doses of methylprednisolone (MP) and to investigate the correlation between expanded disability status scale (EDSS) and MS functional composite (MSFC) during recovery from relapses. METHOD: Patients consecutively diagnosed of clinically defined MS with an episode of less than three weeks course were included. They were evaluated and treated with a single dose of 1,000 mg of MP for three days without oral tapering. Baseline EDSS and at least three MSFC scale measurements were available. Patients were scored with EDSS and MSFC before the treatment and after 1, 4 and 12 weeks. Adverse events were also recorded. Response to treatment was defined as the recovery of at least 1 point in the EDSS or the return to baseline EDSS. RESULTS: Twenty one episodes in 20 patients were treated. Mean baseline EDSS was, 2.5; mean baseline z-score was, 0.15, and mean relapse duration was, 6.8 days. During relapse, mean EDSS worsened to 3.8 and mean z-score to -0.57. At week 1, 33.4% of relapses had responded to treatment, and at weeks 4 and 12, 85.7% had responded. Although mean EDSS and mean z-score had already improved at week 1, mean EDSS did not reach baseline value until week 4 and mean z-score until week 12. EDSS correlated significantly to MSFC in each evaluation as well as to scale changes related to relapse (p;0.05). No serious adverse events were seen. DISCUSSION: Oral high-dose of MP is a safe and effective therapy for MS relapses. Both EDSS and MSFC were sensitive to changes related to relapses although the dynamics of recovery was different, providing complementary information.

Axonal loss is progressive and partly dissociated from lesion load in early multiple sclerosis.

OBJECTIVE: To assess the relationship between the spectroscopically measured axonal damage in the normal-appearing white matter of the brainstem, the total brain T2-hyperintense lesion volume (T2LV), and disability in patients with early relapsing-remitting multiple sclerosis (RRMS). METHODS: Forty-three RRMS patients and 10 sex- and age-matched healthy controls were prospectively studied for 2 years. T2-weighted magnetic resonance (MR) images and proton MR spectroscopy were acquired at the time of recruitment and at year 2. Brainstem was considered, where large tracts join together, as a suitable region to detect early axonal damage. The T2LV was calculated with a semiautomatic program; N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) resonances areas were integrated with the jMRUI program, and the ratios were calculated for the sum of the volume elements represented at brainstem. RESULTS: The basal NAA/Cho ratio was significantly decreased in patients compared with controls. After 2-year follow-up, there was a decrease in the NAA/Cho (-9%; p = 0.002) and NAA/Cr (-13%; p = 0.001) ratios, and an increase in the T2LV (19%; p = 0.043) in multiple sclerosis patients, whereas control subjects had no significant metabolic changes. Significant NAA/Cr ratio decreases were observed in both patients, with and without relapses, whereas T2LV only increased in patients with relapses. The final Expanded Disability Status Scale (EDSS) score correlated with T2LV at baseline, but no significant correlations were found between metabolic values, T2LV change, or EDSS score over the study period. CONCLUSIONS: Our data reveal an early and progressive axonal damage in relapsing-remitting multiple sclerosis. Axonal loss and T2 lesion volume seem to be at least partly dissociated processes in early stages of the disease.

Paraneoplastic vasculitis associated with multiple myeloma.

The association between vasculitis and cancer has been widely reviewed in recent decades. The existence of malignancies in patients with vasculitis has been estimated at about 4.5-8%, haematological neoplasms being the most frequently observed. The haematological malignancies most frequently described are lymphoproliferative diseases such as hairy cell leukaemia and lymphomas. On the contrary, the incidence of paraneoplastic vasculitis in patients with myeloma is low; up to now, we have found nine cases reported on this subject. We report the case of a 73-year-old woman who in 1 year showed three outbreaks of acutely painful, purpuric and ulceronecrotic lesions, localized on the lower extremities. Histopathological study demonstrated thrombosis in the arterioles and leucocytoclastic vasculitis. Complementary tests revealed the presence of multiple myeloma.

Incontinentia pigmenti: a report of ten cases.

A multidisciplinary approach is necessary in the care of patients with incontentia pigmenti (Bloch-Sulzberger syndrome).

Trigeminal neurinomas in infants: report of two cases.

Two cases of trigeminal neurinoma in two infant girls aged 3 and 6 months are reported. Both presented with temporal cranial vault bulging at birth. The 6-month-old patient suffered onset of focal fits 1 month before admission and her neurological examination revealed no abnormalities. The 3-month-old patient had right exophthalmus and a subcutaneous fronto-orbital plexiform neurofibroma at birth. Neurological examination disclosed a sensory deficit of the first trigeminal nerve division. She also had a family medical history of von Reckling-hausen's disease. The incidence of trigeminal neurinomas in children is reviewed. The patients in these two cases are the youngest recorded; the cases are the only ones reported in infants. Clinical, radiological, and therapeutic aspects are discussed.

Injection injury of the sciatic nerve (370 cases).

Injury to peripheral nerves due to injections of therapeutic and other agents is common. The postulated mechanisms of injury include direct needle trauma, secondary constriction by scar, and direct nerve fiber damage by neurotoxic chemicals in the injected agent. Neurological sequelae can range from minor transient sensory disturbance to severe sensory disturbance and paralysis with poor recovery. The recommended treatment has ranged from a conservative approach to immediate operative exposure and irrigation, and has also included early neurolysis or delayed exploration with neurolysis or resection and anastomosis. We present 370 cases of injection injury of the sciatic nerve in children treated during the last 20 years at the Neurosurgical Department of the Hospital La Paz in Madrid, Spain. Pathology, clinical course, treatment, and results are discussed.

[Morphology of Sarcoptes Scabiei (variety hominis) under scanning electron microscopy]. / Morphologie du sarcoptes scabiei (variété hominis) au microscope électronique a balayage.

Some morphologic aspects of S. S. by SEM in twelve parasites (female) extracted from the lesions with a pin are studied. We think that the extraction method and the posterior colocation of the parasite has contributed to its better understanding. We describe the dorsal cleft, a characteristic formation of the sarcoptidos, tapered on both sides with thorns in the form of shark's teeth. We analyze the details of the Ambulacro, constituted by the cut or the strait Pedicelo, with a distal extremity in the form of Condyl in which the suction cups are articulated. We can see, in the anogenital portion, two independent anal and genital orificius and, in the ventral area, the tocostoma, or cleft, where the eggs are deposited. Finally we analyze the bucal organs, the Pedipulpos, the morphology and disposition of the hipostoma and the queliceros.