Optical properties of heavily doped GaAs nanowires and electroluminescent nanowire structures

We present GaAs electroluminescent nanowire structures fabricated by metal organic vapor phase epitaxy. Electroluminescent structures were realized in both axial pn-junctions in single GaAs nanowires and free-standing nanowire arrays with a pn-junction formed between nanowires and substrate, respectively. The electroluminescence emission peak from single nanowire pn-junctions at 10 K was registered at an energy of around 1.32 eV and shifted to 1.4 eV with an increasing current. The line is attributed to the recombination in the compensated region present in the nanowire due to the memory effect of the vapor-liquid-solid growth mechanism. Arrayed nanowire electroluminescent structures with a pn-junction formed between nanowires and substrate demonstrated at 5 K a strong electroluminescence peak at 1.488 eV and two shoulder peaks at 1.455 and 1.519 eV. The main emission line was attributed to the recombination in the p-doped GaAs. The other two lines correspond to the tunneling-assisted photon emission and band-edge recombination in the abrupt junction, respectively. Electroluminescence spectra are compared with the micro-photoluminescence spectra taken along the single p-, n- and single nanowire pn-junctions to find the origin of the electroluminescence peaks, the distribution of doping species and the sharpness of the junctions.

XeF(2) gas-assisted focused-electron-beam-induced etching of GaAs with 30 nm resolution

We demonstrate the gas-assisted focused-electron-beam (FEB)-induced etching of GaAs with a resolution of 30 nm at room temperature. We use a scanning electron microscope (SEM) in a dual beam focused ion beam together with xenon difluoride (XeF(2)) that can be injected by a needle directly onto the sample surface. We show that the FEB-induced etching with XeF(2) as a precursor gas results in isotropic and smooth etching of GaAs, while the etch rate depends strongly on the beam current and the electron energy. The natural oxide of GaAs at the sample surface inhibits the etching process; hence, oxide removal in combination with chemical surface passivation is necessary as a strategy to enable this high-resolution etching alternative for GaAs.

Effect of laser therapy on DNA damage

BACKGROUND AND OBJECTIVE

Whereas the biostimulative effect on tissues using low intensity laser therapy for treating many diseases has been described, the photobiological basis and adverse effects are not well understood. The aim of this study, using experimental models, is to observe the combined effect of physical damage (laser) and a chemical agent (hydrogen peroxide) on Escherichia coli cultures and bacterial plasmids.

MATERIALS AND METHODS

Survival of E. coli AB1157 (wild type) and BW9091 (xth(-)) cultures were used as an experimental model to assess the effect of agents on DNA, also agarose gel electrophoretic profile of bacterial plasmids for studying single and double strand breaks in DNA exposed to laser irradiation and in DNA pre-exposed to laser and subsequently incubated with hydrogen peroxide.

RESULTS

Data indicate low intensity laser: (i) did not alter the survival of E. coli cultures, (ii) pre-exposure had a protective effect against lethal action of hydrogen peroxide on E. coli cultures, and (iii) did not alter the electrophoretic profile and action of hydrogen peroxide on plasmids. This suggests that low intensity therapeutic red laser doses at different emission modes induces sub-lethal effects on E. coli wild type and exonuclease III mutant cultures inducing protective mechanisms against lethal action of hydrogen peroxide. Laser action on bacterial plasmids is related to lesions other than single or double DNA strands breaks.

CONCLUSIONS

This study shows a protective effect or DNA repair mechanism induction by pre-exposure to low intensity red laser on the lethal action of oxidant agents and, therefore, laser therapy protocol should consider fluencies, wavelength and tissue conditions before beginning treatment.

Treatment of acute, non-traumatic pain using a combination of diclofenac-cholestyramine, uridine triphosphate, cytidine monophosphate, and hydroxycobalamin

This randomized, controlled, double-blind clinical study in parallel groups evaluated the safety and efficacy of an oral combination diclofenac-cholestyramine, nucleotides (uridine and cytidine) and vitamin B12 versus the oral combination of nucleotides and vitamin B12 in the treatment of acute, non-traumatic pain. Subjects received twice-daily, 10-day oral administration of diclofenac-cholestyramine + uridine + cytidine + vitamin B12 (Group DN, n=40) or uridine + cytidine + vitamin B12 (Group NB, n=41). The primary study endpoint was the number of subjects with VAS reduction of >30mm after 10 days of treatment. Secondary endpoints included the number of patients with improvement >5 points in the Patient Functionality Questionnaire after 10 days of treatment, and the number of subjects presenting adverse events. Treatment with the combination of diclofenac-cholestyramine, nucleotides and Vitamin B12 resulted in a higher number of subjects with VAS score reductions >30mm after 10 days of treatment (87.5% subjects) than in the control group administered nucleotides and Vitamin B12 (51.23% of subjects), (p>0.0006). A significantly higher number of subjects in the DN group (80%) had a score reduction of >5 points in the Patient Functionality Questionnaire at after 10 days of treatment compared to Group NB (29.3%), (p<0.001). The number of subjects presenting AEs did not vary significantly between treatment groups (p=0.587). The combination of diclofenac-cholestyramine with uridine, cytidine and vitamin B12 was well-tolerated over a 10-day treatment period. The combination reduced pain and improved functionality among subjects presenting acute, non-traumatic pain in the lower back, hips, and neck.

Diclofenac plus B vitamins versus diclofenac monotherapy in lumbago: the DOLOR study

OBJECTIVES

To assess the influence of vitamins B1, B6 and B12 on the analgesia success achieved by diclofenac in subjects with acute lumbago.

RESEARCH DESIGN AND METHODS

A randomised, double blind controlled clinical study in parallel groups, in which subjects received twice-daily oral administration of either the combination therapy, Group DB (50 mg diclofenac plus 50 mg thiamine, 50 mg pyridoxine and 1 mg cyanocobalamin) or diclofenac monotherapy, Group D (50mg diclofenac). The study period lasted a maximum of 7 days. If sufficient pain reduction was achieved (defined as Visual Analogue Scale <20 mm and patient's satisfaction), subjects could withdraw from the treatment after 3 or 5 days. All subjects gave written informed consent to participate in the study.

MAIN OUTCOME MEASURES

The primary confirmatory study objective was to determine the number of patients with sufficient pain reduction after 3 days of treatment.

RESULTS

Three hundred and seventy-two subjects were allocated at random to either treatment group: Group DB - 187 subjects and Group D - 185 subjects. After 3 days of treatment, a statistically significant higher proportion of subjects in Group DB (n = 87; 46.5%) than in Group D (n = 55; 29%) terminated the study due to treatment success (chi(2): 12.06; p = 0.0005). Furthermore, the combination therapy yielded superior results in pain reduction, improvement of mobility and functionality. Drug safety monitoring profile throughout the trial was within the expected safety profile of diclofenac.

CONCLUSIONS

The combination of diclofenac with B vitamins was superior to diclofenac monotherapy in lumbago relief after 3 days of treatment. As a study drawback, daily VAS measurements were only recorded until subject withdrawal from treatment, whether after 3, 5, or 7 days. There were no differences in safety profile between the two study groups.

Validation of tissue microarray technology in malignant peripheral nerve sheath tumours

BACKGROUND

It has been suggested that the donor tissue cores used in tissue microarrays (TMAs) may not be representative of the whole tissue section.

AIM

To validate the use of TMA technology in the study of malignant peripheral nerve sheath tumours (MPNSTs).

METHODS

A TMA was constructed containing five independent core biopsy samples of 14 formalin-fixed, paraffin-embedded MPNSTs. The immunohistochemical (IHC) results of the five cores from the same tissue block on TMA were compared with readings from whole sections using two antibodies: anti-Ki-67 and anti-S-100. Digital image analysis was performed to calculate the percentage of positive stain areas. The agreement between IHC results obtained with TMA cores and whole sections was assessed using the kappa statistic.

RESULTS

There was good to very good agreement between IHC results for whole and TMA sections from MPNSTs. In relation to S-100, very good agreement (92% agreement; kappa = 0.77) was observed using a minimum of four TMA cores. Staining results for Ki-67 from at least four readable TMA cores were the same as those for the whole section in 86% of cases, with good agreement, using weighted kappa statistics (kappa = 0.63).

CONCLUSIONS

This study indicates that the TMA technique can be used in the IHC study of MPNSTs, even with the use of heterogeneous markers such as S-100 protein.

Progesterone and Estrogen Receptors in Neurofibromas of Patients with NF1

Neurofibromatosis type 1 (NF1) or von Recklinghausen disease is a genetic disorder affecting the growth of cells in nervous system. One of the most remarkable characteristics of this disease is the development of benign tumors of the nervous system (neurofibromas).The purpose of this study was to test tissue samples taken from neurofibromas and plexiform neurofibromas of NF1 patients for the presence of estrogen and progesterone receptors. We used previously collected samples from patients registered in the database of the Centro Nacional de Neurofibromatose (CNNF-Brazil). Samples from twenty-five patients in the database presenting plexiform neurofibromas (N1 group) and 25 samples from the same database from patients presenting neurofibromas (N2 group) were tested.We observed positive staining for progesterone receptors in 13 of the neurofibroma samples and 19 of the plexiform neurofibroma samples. Among the neurofibroma samples, we observed one sample with positive estrogen receptor staining, but none of the plexiform neurofibroma samples showed positive staining. We suggest further studies to investigate in greater depth possible hormonal influences on the development and growth of neurofibromas and plexiform neurofibromas in NF1.

Neurofibromatose tipo 1 na infância: revisão dos aspectos clínicos

OBJETIVO: Realizar uma revisão da literatura sobre neurofibromatose tipo 1 (NF1) em crianças e adolescentes, enfatizando as manifestações clínicas. FONTES DE DADOS: Artigos publicados, indexados na base de dados Medline e publicados entre 1998 a 2007, buscados pelos seguintes termos: "neurofibromatosis type 1", "neurofibroma", "von Recklinghausen" e "optic pathway gliomas". SÍNTESE DOS DADOS: A NF1 é uma doença genética autossômica dominante, crônica e progressiva, com incidência de 1/2.000 a 1/7.800 nascidos vivos. Tem sido observada em diferentes partes do mundo, em todas as raças e nos dois sexos. Metade dos casos representa mutações novas. A taxa de mutação para o gene NF1 é de 1/10.000, a qual se deve ao fato do gene ser grande e possuir estrutura interna atípica, que predispõe a deleções e mutações. O diagnóstico presuntivo da NF1 é feito por critérios clínicos. As três principais manifestações - neurofibromas, manchas café-com-leite e nódulos de Lisch - ocorrem em mais de 90% dos pacientes até a puberdade. CONCLUSÕES: Os cuidados com os pacientes com NF1 devem antecipar as principais complicações e oferecer um tratamento precoce. No aconselhamento genético, é importante informar pais e familiares a respeito do panorama geral da doença e suas possíveis complicações, enfatizando que a maioria dos pacientes apresenta vida saudável e produtiva.

Prevalence of plexiform neurofibroma in children and adolescents with type I neurofibromatosis

OBJECTIVE

To assess prevalence of plexiform neurofibroma in children and adolescents with type I neurofibromatosis and its malignant potential.

METHODS

A retrospective study was conducted through analysis of the database at Centro Nacional de Neurofibromatose [Brazilian Neurofibromatosis Center], collected from the following reference services between 1996 and 2004: Instituto de Dermatologia Prof. Rubem David Azulay da Santa Casa de Misericórdia do Rio de Janeiro, Instituto de Pediatria e Puericultura Martagão Gesteira da Universidade Federal do Rio de Janeiro and Department of Immunology and Microbiology at Faculdade de Medicina de Teresópolis.

RESULTS

Over that period, 104 patients aged between 1-17 years were admitted with clinical diagnosis of type I neurofibromatosis. Of these, 53 were male and 51 were female, and 28 patients (15 male and 13 female) had plexiform neurofibroma (26.9%). Division by age group resulted in 21.42% (six) between 1-5 years; 35.71% (10) between 6-12 years and 42.85% (12) between 13-17 years. Of the 104 patients, two developed a malignant peripheral nerve sheath tumor (1.92%).

CONCLUSIONS

Plexiform neurofibromas are relatively common manifestations in patients with type I neurofibromatosis and may be a cause of significant increase in morbidity and mortality among patients. In this study, we conclude that frequency of plexiform neurofibroma and its malignant potential in the population studied is in agreement with data from the international literature.

Serum IgE levels in neurofibromatosis 1

A descriptive case study was performed on 75 patients with NF1 (neurofibromatosis type 1) from the CNNF (Brazil) database. Serum IgE levels were determined using the IgE radioimmunosorbent test, with the reference values of 75-502 IU mL(-1). The patients were divided into groups, with 25 patients presenting plexiform neurofibromas, 25 presenting neurofibromas and 25 presenting no neurofibromas. The purposes of this study were to determine the serum IgE levels of patients with NF1 presenting plexiform neurofibromas, neurofibromas and no neurofibromas, as well as to determine possible correlations between serum IgE levels and the size of the plexiform neurofibromas and neurofibromas presented by these patients. Elevated serum IgE levels were observed in all the patient groups. We did not observe a correlation between IgE levels and age in these patients; however, we did observe correlations between IgE levels and neurofibroma and plexiform neurofibroma size. We suggest further studies to confirm these results and to investigate in greater depth the possible role of IgE in the development and growth of neurofibromas and plexiform neurofibromas in NF1.

Angiogenesis in normal and neoplastic ovaries

Ovarian physiology is intricately connected to hormonally regulated angiogenic response. Recent advances in the post genomic revolution have significantly impacted our understanding of ovarian function. In an angiogenesis perspective, the ovary offers a unique opportunity to unravel the molecular orchestration of blood vessel development and regression under normal conditions. A majority of ovarian cancers develop from the single layer of epithelium surrounding the ovaries. Angiogenesis is critical for the development of ovarian cancer and its peritoneal dissemination. The present review summarizes recent findings on the angiogenic response in neoplastic ovaries and discusses the prospects of using anti-angiogenic approaches to treat ovarian cancer.

[Treatment with enoxaparin adapted to the fertility programs in women with recurrent abortion and thrombophilia]

Acquired and inherited thrombophilia are associated with recurrent pregnancy loss (RPL). Antithrombotic therapy could restore hemostatic balance and improve early placentation and gestational outcome. We evaluated the efficacy of enoxaparin adapted to the fertility program for prevention of pregnancy loss in 35 women (W) with early RPL and thrombophilia. Previous to the diagnosis of thrombophilia, they had had a total of 105 gestations of which 89 (85%) ended in early pregnancy loss. After diagnosis of thrombophilia, 35 subsequent pregnancies were treated with enoxaparin. In 5 cases assisted reproductive techniques were necessary to achieve pregnancy due to couple infertility. In 17 W who had had at least one preclinical pregnancy loss, enoxaparin (20 mg/d/s.c.) was started previous to conception and adapted to the fertility program. All the women continued with the gestational regime. Eighteen W with only clinical pregnancy loss started enoxaparin (20 mg twice per day s.c.) after biochemical pregnancy diagnosis. During gestations heparin dose was adjusted with anti Xa test, maintaining a range between 0.3 at 0.6 u/ml. With antithrombotic therapy, 30/35 (85%) of the pregnancies ended in live birth versus 16/105 (15%) of the pregnancies without treatment (p < 0.001). These results suggest that enoxaparin adapted to the fertility program can be effective in the prevention of preclinical and clinical abortion in women with thrombophilia.

Efficacy and safety of moricizine in the maintenance of sinus rhythm in patients with recurrent atrial fibrillation

Maintenance of sinus rhythm is the primary goal of antiarrhythmic drug therapy for recurrent atrial fibrillation (AF). However, concern about proarrhythmic and negative inotropic effects has led to increasing reluctance to administer antiarrhythmic agents for this non-life-threatening arrhythmia. Moricizine is well tolerated in a wide variety of patients, and therefore, may be a safe and effective agent for treating AF. We retrospectively assessed the efficacy and safety of moricizine (mean dose 609 +/- 9 mg/day) in 85 consecutive patients with recurrent AF (2.6 +/- 0.5 years duration, 1.6 +/- 1 failed antiarrhythmic drugs). Structural heart disease was present in 69 (81%), but no recent myocardial infarct (< or =90 days) was present; mean left atrial size was 46 +/- 1 mm, and mean left ventricular ejection fraction was 0.51 +/- 0.01. Moricizine was discontinued because of unsuccessful direct-current cardioversion (n = 5) or clinically unacceptable side effects (n = 6); 6 patients developed transient side effects not requiring discontinuation. Of the 74 patients continuing therapy, 68% remained in sinus rhythm after 6 months, and 59% after 12 months. During a follow-up (21 +/- 2 months), there were neither deaths nor adverse effects requiring discontinuation of therapy. Thus, moricizine was effective, safe, and well tolerated in our patient cohort with AF.

Ligand design package (Ludi--MSI) applied to known inhibitors of the HIV-1 protease. Test of performance

Performance of the Ludi (Insight II--MSI, ver. 98.0) program for computer-aided Ligand Design was tested using four crystallographic complexes of inhibitors with the HIV-1 protease. Possibility of reconstruction of the side chains and the peptide bond of the inhibitors, as well as attempt to construct de novo the central parts of these inhibitors, starting from the native structure of the enzyme, was studied. Results points that Ludi, although helpful, is merely initial tool for computer aided drug design. Moreover, some improvement of the program code is needed.