P–398 Decidualization inhibits the expression of CXCR3-binding chemokines by human decidual stromal cells. Role in maternal-fetal immune tolerance

Study question

We aimed to analyze the effects of decidualization on the expression of chemokines that attract abortogenic T cells by human DSCs.

Summary answer

Decidualization inhibits the expression of chemokines that attract Th1 and Tc1 cells by DSCs, thereby preventing the arrival of abortogenic T cells into the decidua.

What is known already

Decidual stromal cells (DSCs) are the most abundant cells in the human decidua, the tissue that constitutes the maternal component of the placenta. Numerous evidences confirm that DSCs play a key role in maternal-fetal immune tolerance. In normal pregnancy, DSCs undergo a process of differentiation (decidualization) under the effect of progesterone and other pregnancy hormones. Decidualized DSCs become rounded and secrete prolactin, IL–15 and other factors. In the mouse, it has been observed that during pregnancy, DSCs inhibit the expression of chemokines that attract abortogenic Th1 and Tc1 cells from blood to the decidua.

Study design, size, duration

We compared the expression of CXCR3-binding chemokines by undifferentiated and decidualized human DSCs. We also compared the capacity of these cells to attract activated Th1 and Tc1 cells in vitro. Ten DSC lines were obtained from elective vaginal terminations of first-trimester pregnancies (6–11 weeks). Donors were healthy women aged 20–30 years. Informed consent was obtained from each donor. This study was approved by the Research and Ethics Committee of the University of Granada.

Participants/materials, setting, methods

Decidual stromal cell lines were established as previously described. These lines were decidualized with progesterone and cAMP in vitro. The expression of chemokines by these cells was studied by RT-PCR. Peripheral blood lymphocytes were activated with PHA, anti-CD28 and IL–2. As a consequence of this activation, CXCR3+ Th1 and Tc1 cells were produced. We used a migration assay in Transwell chambers to study the capacity of DSCs to attract these activated T cells.

Main results and the role of chance

We observed that those chemokines that bind to CXCR3, a chemokine receptor detected in activated Th1 and Tc1 cells, were not expressed by either undifferentiated and decidualized DSCs (CXCL9) or their expression was inhibited in decidualized DSCs (CXCL10 P < 0.01, CXCL11 P < 0.05). We found that conditioned media of undifferentiated DSCs decreased the migration of CXCR3+ activated T cells (Th1 and Tc1 cells) (P < 0.05), and this effect was even stronger with conditioned media of decidialized DSCs P < 0.001). These results demonstrated that decidualization of DSCs during pregnancy inhibits the expression of chemokines that attract Th1 and Tc1 cells by DSCs, thereby preventing the arrival of abortogenic T cells into the decidua.

Limitations, reasons for caution

This is an in vitro study due to the impossibility of performing an in vivo study in humans for ethical reasons.

Wider implications of the findings: Several publications have shown that DSCs have a therapeutic effect in various Th1-associated diseases. Our results explain this effect and suggest the extension of the use of these cells in the treatment of this type of diseases.

Trial registration number

Not applicable

Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys

CONTEXT

Yebes 40m radio telescope is the main and largest observing instrument at Yebes Observatory and it is devoted to Very Long Baseline Interferometry (VLBI) and single dish observations since 2010. It has been covering frequency bands between 2 GHz and 90 GHz in discontinuous and narrow windows in most of the cases, to match the current needs of the European VLBI Network (EVN) and the Global Millimeter VLBI Array (GMVA).

AIMS

Nanocosmos project, a European Union funded synergy grant, opened the possibility to increase the instantaneous frequency coverage to observe many molecular transitions with single tunnings in single dish mode. This reduces the observing time and maximises the output from the telescope.

METHODS

We present the technical specifications of the recently installed 31.5 - 50GHz (Q band) and 72 - 90.5 GHz (W band) receivers along with the main characteristics of the telescope at these frequency ranges. We have observed IRC+10216, CRL 2688 and CRL 618, which harbour a rich molecular chemistry, to demonstrate the capabilities of the new instrumentation for spectral observations in single dish mode.

RESULTS

The results show the high sensitivity of the telescope in the Q band. The spectrum of IRC+10126 offers a signal to noise ratio never seen before for this source in this band. On the other hand, the spectrum normalised by the continuum flux towards CRL 618 in the W band demonstrates that the 40 m radio telescope produces comparable results to those from the IRAM 30 m radio telescope, although with a smaller sensitivity. The new receivers fulfil one of the main goals of Nanocosmos and open the possibility to study the spectrum of different astrophysical media with unprecedented sensitivity.

Multidisciplinary management of giant cervicothoracic cutaneous squamous cell carcinoma

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Non treated squamous cell carcinoma could present as an uncontrollable and substantial disaurement neoplasm.

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Squamous cell carcinoma that are diagnosed early and successfully treated by surgical excision, has a better forecast.

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When a patient present with a gigant squamous cell carcinoma always requires a multidisciplinary team.

Introduction

Cutaneus squamous cell carcinoma (SCC) is the second most common type of nonmelanoma skin cancer. SCC is a malignant neoplasm of the skin characterized by aberrant proliferation of keratinocytes.

Presentation case

We report multidisciplinary surgical management of a 36-year-old male who presented with a huge cutaneous protruding tumor of the cervicothoracic wall. Clinically, he presented with a growing mass on the anterior cervicothoracic wall 3 years ago. Microscopic examination revealed SCC. He underwent complete excision of the lesion. The patient neglected attending our oncological department for receiving chemotherapy. Today, one year after surgery, he is alive without evidence of disease recurrence.

Discussion

SCC treatment depends on location of the lesion, involvement of neighboring structures, functional level of the patient, and the patient’s acceptance of the proposed management strategy.

Conclusion

We conclude that SCC can grow to a huge size if left untreated. Surgery by a multidisciplinary surgical team is the primary mode of treatment, followed by chemotherapy if necessary.

Nitroxide amide-BODIPY probe behavior in fibroblasts analyzed by advanced fluorescence microscopy

A novel synthesized nitroxide amide-BODIPY prefluorescent probe was used to study cellular redox balance that modulates nitroxide/hydroxylamine ratio in cultured human fibroblasts. FLIM quantitatively differentiated between nitroxide states of the cytoplasm-localized probe imaged by TIRF, monitoring nitroxide depletion by hydrogen peroxide; eluding incorrect interpretation if only fluorescence intensity is considered.

Allele frequencies and other forensic parameters of the HID-Ion AmpliSeq™ Identity Panel markers in Basques using the Ion Torrent PGM™ platform

The HID-Ion AmpliSeq™ Identity Panel amplifies 90 autosomal SNPs and 34 Y- SNPs with massively parallel sequencing (MPS) using the Ion Torrent PGM™ platform. In the present study, 105 Basques were analyzed to assess this panel. All loci were in Hardy-Weinberg equilibrium and no association between them was detected. Forensic parameters were calculated as 5.74×10^-36 for combined match probability and 99.99998% for combined power of exclusion. In conclusion, the HID Identity panel and the use of this new MPS technology are very promising tools for paternity testing and human identification in routine casework in the forensic field.

QDs decorated with thiol-monomer ligands as new multicrosslinkers for the synthesis of smart luminescent nanogels and hydrogels

QDs decorated with thiol-monomer ligands as new multicrosslinkers for the synthesis of smart (photoluminescent and pH/temperature sensitive) nanogels and hydrogels.

The Latin American Biological Dosimetry Network (LBDNet)

Biological Dosimetry is a necessary support for national radiation protection programmes and emergency response schemes. The Latin American Biological Dosimetry Network (LBDNet) was formally founded in 2007 to provide early biological dosimetry assistance in case of radiation emergencies in the Latin American Region. Here are presented the main topics considered in the foundational document of the network, which comprise: mission, partners, concept of operation, including the mechanism to request support for biological dosimetry assistance in the region, and the network capabilities. The process for network activation and the role of the coordinating laboratory during biological dosimetry emergency response is also presented. This information is preceded by historical remarks on biological dosimetry cooperation in Latin America. A summary of the main experimental and practical results already obtained by the LBDNet is also included.

Analysis of uni and bi-parental markers in mixture samples: Lessons from the 22nd GHEP-ISFG Intercomparison Exercise

Since 1992, the Spanish and Portuguese-Speaking Working Group of the ISFG (GHEP-ISFG) has been organizing annual Intercomparison Exercises (IEs) coordinated by the Quality Service at the National Institute of Toxicology and Forensic Sciences (INTCF) from Madrid, aiming to provide proficiency tests for forensic DNA laboratories. Each annual exercise comprises a Basic (recently accredited under ISO/IEC 17043: 2010) and an Advanced Level, both including a kinship and a forensic module. Here, we show the results for both autosomal and sex-chromosomal STRs, and for mitochondrial DNA (mtDNA) in two samples included in the forensic modules, namely a mixture 2:1 (v/v) saliva/blood (M4) and a mixture 4:1 (v/v) saliva/semen (M8) out of the five items provided in the 2014 GHEP-ISFG IE. Discrepancies, other than typos or nomenclature errors (over the total allele calls), represented 6.5% (M4) and 4.7% (M8) for autosomal STRs, 15.4% (M4) and 7.8% (M8) for X-STRs, and 1.2% (M4) and 0.0% (M8) for Y-STRs. Drop-out and drop-in alleles were the main cause of errors, with laboratories using different criteria regarding inclusion of minor peaks and stutter bands. Commonly used commercial kits yielded different results for a micro-variant detected at locus D12S391. In addition, the analysis of electropherograms revealed that the proportions of the contributors detected in the mixtures varied among the participants. In regards to mtDNA analysis, besides important discrepancies in reporting heteroplasmies, there was no agreement for the results of sample M4. Thus, while some laboratories documented a single control region haplotype, a few reported unexpected profiles (suggesting contamination problems). For M8, most laboratories detected only the haplotype corresponding to the saliva. Although the GHEP-ISFG has already a large experience in IEs, the present multi-centric study revealed challenges that still exist related to DNA mixtures interpretation. Overall, the results emphasize the need for further research and training actions in order to improve the analysis of mixtures among the forensic practitioners.

Multiamino polymeric capping of fluorescent silver nanodots as an effective protective, amphiphilic and pH/thermo-responsive coating

New multiamino thermosensitive polymers based on MEO₂MA have been described and used to the in situ synthesis of polymeric capped silver nanodots. The new highly luminescent hybrids show amphiphilic and pH/thermo-responsiveness.

[Superficial mycoses in patients from Anzoátegui state, Venezuela, period 2002-2012]

Superficial fungal diseases that affect the skin and its appendages are frequently seen in basic triage and in dermatology services. These diseases are distributed in Venezuela with an incidence of 92.9%. The aim of this study was to determine the genera and species that cause dermatomycoses in residents of Anzoátegui state, Venezuela, during the period 2002-2012. A total of 4257 patients with a presumptive diagnosis of superficial mycoses were studied, with ages from 7 months to 79 years. The overall prevalence was 30.9%. The most frequent were dermatophytosis (44.7%). M. canis produced 148 cases of tinea capitis. Three dermatophytic agents represented 95% of all cases, with a significant predominance of T. mentagrophytes with 50%. Candidosis occurred in 28.4%. C. albicans, and the C. parapsilosis complex, were responsible for 80% of the cases. The other species identified were C. tropicalis (n = 41, 11.0%), C. glabrata (n = 10, 2.7%), C. guilliermondii (n = 6, 1.6%), C. krusei (n = 4, 1.1%). Pityriasis versicolor occurred in 22.4% of the cases studied, and less frequently were present onychomycosis produced by a non dermatophytic mold: Fusarium oxysporum (n = 34, 65.4%), Aspergillus terreus (n=16, 30.8%) and Scytalidium dimidiatum (n=2; 3.8%). Rare cases of Trichosporon onychomycosis (0.5%) and one case of black tinea were also found. Health education in the population is recommended to promote measures to prevent transmission of these fungi and prevent the spread of this silent public health problem.

Interlaboratory comparison of dicentric chromosome assay using electronically transmitted images

The bottleneck in data acquisition during biological dosimetry based on a dicentric assay is the need to score dicentrics in a large number of lymphocytes. One way to increase the capacity of a given laboratory is to use the ability of skilled operators from other laboratories. This can be done using image analysis systems and distributing images all around the world. Two exercises were conducted to test the efficiency of such an approach involving 10 laboratories. During the first exercise (E1), the participant laboratories analysed the same images derived from cells exposed to 0.5 and 3 Gy; 100 images were sent to all participants for both doses. Whatever the dose, only about half of the cells were complete with well-spread metaphases suitable for analysis. A coefficient of variation (CV) on the standard deviation of ∼15 % was obtained for both doses. The trueness was better for 3 Gy (0.6 %) than for 0.5 Gy (37.8 %). The number of estimated doses classified as satisfactory according to the z-score was 3 at 0.5 Gy and 8 at 3 Gy for 10 dose estimations. In the second exercise, an emergency situation was tested, each laboratory was required to score a different set of 50 images in 2 d extracted from 500 downloaded images derived from cells exposed to 0.5 Gy. Then the remaining 450 images had to be scored within a week. Using 50 different images, the CV on the estimated doses (79.2 %) was not as good as in E1, probably associated to a lower number of cells analysed (50 vs. 100) or from the fact that laboratories analysed a different set of images. The trueness for the dose was better after scoring 500 cells (22.5 %) than after 50 cells (26.8 %). For the 10 dose estimations, the number of doses classified as satisfactory according to the z-score was 9, for both 50 and 500 cells. Overall, the results obtained support the feasibility of networking using electronically transmitted images. However, before its implementation some issues should be elucidated, such as the number and resolution of the images to be sent, and the harmonisation of the scoring criteria. Additionally, a global website able to be used for the different regional networks, like Share Points, will be desirable to facilitate worldwide communication.

Automatic analysis of silver-stained comets by CellProfiler software

The comet assay is one of the most widely used methods to evaluate DNA damage and repair in eukaryotic cells. The comets can be measured by software, in a semi-automatic or automatic process. In this paper, we apply the CellProfiler open-source software for automatic analysis of comets from digitized images, reporting the percentage of tail DNA. A side-by-side comparison of CellProfiler with CASP software demonstrated good agreement between the two packages. Our work demonstrates that automatic measurement of silver-stained comets with open-source software is possible, providing significant time savings.

Metastatic lymph node ratio versus number of metastatic lymph nodes as a prognostic factor in gastric cancer

OBJECTIVE

Knowledge of prognostic factors in gastric cancer is essential to decide on single patient management. We aim to establish the value of lymph node ratio compared to lymph node involvement in the prediction of gastric cancer survival and treatment approach.

METHODS

Charts of ninety-six consecutive patients undergoing gastrectomy for resectable gastric cancer were reviewed between January 1996 and December 2005. Receiver operating characteristic (ROC) curves were plotted to verify the accuracy of metastatic lymph node ratio (MLNR) and number of metastatic lymph node (NMLN) cut-off values for survival prediction. Patients were divided into two groups according to ROC curve cut-offs and accuracy in prognosis was reviewed.

RESULTS

ROC curves showed that 5 metastatic nodes and a node ratio value of 20% had the best survival prognostic correlation. The median survival of patients with MLNR and NMLN were similar according to cut-off determinations (≤ 5/> 5 metastatic nodes and ≤20/>20% lymph node ratio). Five-year survival rates were 70.9% vs 17.1% and 72.4% vs 15.6%, respectively (p < 0.001). Positive correlation coefficient was found between the number of excised nodes and the number of metastatic nodes.

CONCLUSION

Number of metastatic lymph nodes showed greater accuracy than lymph node ratio for survival prediction in gastric cancer.

Laser emission from mirrorless waveguides based on photosensitized polymers incorporating POSS

Laser emission from leaky waveguides based in dye-doped organic gain media incorporating Polyhedral Oligomeric Silsesquioxanes (POSS) nanoparticles is reported. The samples consist of thin film gain media deposited onto glass substrate defining a planar asymmetric slab waveguide, which does not incorporate any resonant substructure. The presence of POSS results in additional amplified spontaneous emission (ASE) spectral narrowing, and conditions have been found for which directional multimode laser emission is achieved. The spectral narrowing is ascribed to the photon path enlargement caused by a non-resonant feedback mechanism provided by individual scatterers, which enhances incoherently the magnitude of the amplification process. On the contrary, the appearance of multimode lasing is attributed to coherent random lasing from a many scatterers collective effect.

[Evidence-based ophthalmology: critical evaluation of the literature in relation to diagnostic tests]

PURPOSE

In general, articles on diagnostic tests have a very poor methodological quality. If we translate their conclusions to daily practice without a proper analysis it is easy to see a typical trend: physicians use new (and expensive) tests without increasing diagnostic capacity; they only increase the health budget. Evidence-based medicine (EBM) consists of using the best evidence in decision-making. It deals with selected and relevant information, supported by data obtained through the most rigorous scientific method: epidemiology and statistics. Critical evaluation of papers related to diagnostic tests is our aim. We provide with basic skills for evaluation and analysis of papers by means of simple topics on statistics, design of clinical assays and clinical epidemiology.

METHODS

Review of the medical literature.

RESULTS

To evaluate papers on diagnostic tests and to use a test correctly, it is necessary to know its diagnostic capacity, the level of certainty to start treatment, the probability of having the disease before using the test and the test capacity to change that probability.

CONCLUSIONS

The maximum performance of a test is reached when it is used in a maximum uncertainty situation (disease probability 50%). Its highest usefulness is obtained when pre-test probability is maximal, after a careful review of the patient's history and a complete patient examination.

Amplified spontaneous emission and optical gain measurements from pyrromethene 567--doped polymer waveguides and quasi-waveguides

Amplified spontaneous emission from planar waveguides and quasi-waveguides based on Pyrromethene 567-doped poly(methyl methacrylate) thin films deposited onto quartz and glass substrates is investigated. Films with different thickness were prepared and pumped optically at 532 nm with pulses of up to 8 MW/cm(2). Pump thresholds for the onset of ASE emission, optical gains and losses were assessed. Net gain coefficients were estimated by fitting the data provided by variable stripe length measurements with a theoretical expression which takes into account saturation. In this way, net gain coefficients of up to 56 +/- 9 cm(-1) at a pump intensity of 5.3 MW/cm(2) for quasi-waveguides and up to 20.6 +/- 2.7 cm(-1) at a pump intensity of 3.4 MW/cm2 for waveguides, were obtained. Loss coefficients in the waveguides were estimated to be 3.8 +/- 0.4 cm-1 and 6.1 +/- 1.3 cm(-1) for 15 microm and 5 microm thick films, respectively. The results obtained seem to indicate a stronger self-mode-restriction capability in the quasiwaveguides than in conventional total internal-reflection waveguides.

Synthesis, structure, and physical properties of hybrid nanocomposites for solid-state dye lasers

We report on the synthesis, structural characterization, physical properties, and lasing action of two organic dyes, Rhodamine 6G (Rh6G) and Pyrromethene 597 (PM597), incorporated into new hybrid organic-inorganic materials, where the organic component was either poly(2-hydroxyethyl-methacrylate) (PHEMA) or copolymers of HEMA with methyl methacrylate (MMA), and the inorganic counterpart consisted of silica derived from hydrolysis-condensation of methyltriethoxysilane (TRIEOS) in weight proportion of up to 30%. Lasing efficiencies of up 23% and high photostabilities, with no sign of degradation in the initial laser output after 100 000 pump pulses at 10 Hz, were demonstrated when pumping the samples transversely at 534 nm with 5.5 mJ/pulse. A direct relationship could be established between the structure of the hybrid materials, analyzed by solid-state NMR, and their laser behavior. An inorganic network dominated by di-/tri- substituted silicates in a proportion approximately 35:65, corresponding to samples of HEMA with 15 and 20 wt % proportion of TRIEOS, optimizes the lasing photostability. The thermal properties of these materials, together with the high homogeneity revealed by atomic force microscopy (AFM) images, even in compounds with high silica content, indicate their microstructure to be a continuous phase, corresponding to the polymer matrix, which "traps" the silica components at molecular level via covalent bonding, with few or no silica islands.

Allele frequencies of six miniSTR loci (D10S1248, D14S1434, D22S1045, D4S2364, D2S441 and D1S1677) in a Spanish population

Allele frequencies and forensic parameters for six miniSTR autosomal loci (D10S1248, D14S1434, D22S1045, D4S2364, D2S441 and D1S1677) were obtained from a sample of 264 unrelated individuals from Spain. No significant deviations from Hardy-Weinberg expectations were found. Due to the small PCR products (<125 bp), the use of these non-CODIS (NC) miniSTRs can increase the probability that a degraded sample can be typed. Additionally, these systems can be used in routine paternity analyses where more markers are needed to increase the power of exclusion or in complex paternity cases (e.g. involving closely related individuals).

Population genetic data for 18 STR loci in Costa Rica

Allele frequencies for 18 STR autosomal loci (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, D16S539, TH01, TPOX, CSF1PO, Penta D, Penta E, D19S433, D2S1338 and SE33) were obtained from a sample of 191-500 unrelated individuals from Costa Rica, Central America.

STR data for 11 autosomal STR markers from Costa Rica, Central America

Allele frequencies for 11 STR autosomal loci (F13A01, F13B, FESFPS, LPL, CSF1PO, TH01, TPOX, VWA, D16S539, D7S820 and D13S317) were obtained from a sample of 200 unrelated individuals from Costa Rica, Central America.

Mitochondrial DNA haplotyping revealed the presence of mixed up benign and neoplastic tissue sections from two individuals on the same prostatic biopsy slide

DNA typing was requested to investigate a presumptive cancer diagnosis error by confirming whether benign and cancerous prostatic tissue in the same presurgical haematoxylin and eosin stained slide belonged to the same person. After independent histological re-examination of the slide by a pathologist, manual slide dissection was used to guarantee independent and high recovery DNA isolation from each tissue section, avoiding carryover and background contamination. Nuclear DNA quantification performed by real time polymerase chain reaction (PCR) revealed the absence of human DNA for short tandem repeat (STR) typing. Mitochondrial DNA was only obtained by performing PCR of very short fragments ( approximately 100 bp), indicating high DNA degradation. Different low frequency hypervariable region I haplotypes were obtained from each tissue section (normal tissue section haplotype: 16224C, 16234T, 16311C, 16356C; cancer tissue section haplotype: 16256T, 16270T, 16293G). Only the normal tissue section haplotype matched that obtained from the patient's blood sample, indicating that the cancer tissue section originated from an unknown patient. These results supported the hypothesis of sample mix up during block processing or slide preparation by a carryover mechanism. Mitochondrial genetic typing is recommended to exclude the possibility of carryover artefacts when low DNA content and high degradation compromise conventional STR typing.

Polymer-Filled Nanoporous Silica Aerogels as Hosts for Highly Stable Solid-State Dye Lasers

New hybrid solid-state dye laser materials based on highly porous silica aerogels have been synthesized. The open porous network of the aerogel was saturated with laser dyes dissolved in appropriate organic monomers, and polymerization took place inside the silica structure. The resulting polymer-filled nanoporous aerogel (PFNPA) was cast in a cylindrical shape, forming monoliths that were used as gain media in solid-state dye lasers. When the PFNPA incorporated pyrromethene dyes, highly photostable laser emission with good lasing efficiency was obtained. Under the demanding conditions of tightly focused transversal pumping with 532 nm, 5 mJ pulses at 10 Hz repetition rate, the commercial dye Pyrromethene 567 exhibited laser action with only a 10% drop in the laser output after 10(6) pump pulses in the same position of the sample.

The efficiency of titanocene as photoinitiator in the polymerization of dental formulations

A comparative kinetic study of the polymerization of tetraethyleneglycol dimethacrylate (TEEGDM) under visible light irradiation was carried out in order to determine the effectiveness of titanocene as photoinitiator in this process. The pair camphorquinone/dimethylaminoethyl methacrylate, CQ/DMAEMA (0.5/0.5%, by weight), was used as a reference photoinitiatior system. The reactions were carried out both in the presence and absence of oxygen (in N2) and with variable and constant titanocene concentration and incident light intensity. It was observed that in both atmospheres the polymerization reaction commenced rapidly and its initial rate was comparable with that obtained in the presence of the classic initiation system. However, after reacting for a few seconds this process suffered abrupt deactivation, this tendency being more noticeable at low titanocene concentrations. To explain the observed kinetic behavior, the study of the photofragmentation of titanocene upon irradiation with visible light in both atmospheres was carried out. The quantum yield calculated in the presence of O2 (phifr = 8 at 465 nm) suggests the existence of a chain reaction with participation of oxygen, and this explains, in turn, the high value of the initial rate of polymerization and also the rapid disappearance of the photoinitiator. In an inert atmosphere the photofragmentation occurs in a conventional way, this being a very effective process with quantum yield of 0.7 at 465 nm. However, it seems that only a small part of the active species acts as initiating radicals and these are not sufficient to achieve the appropriate monomer conversion.

Strategies for neuroprotection against L-trans-2,4-pyrrolidine dicarboxylate-induced neuronal damage during energy impairment in vitro

Increased levels of extracellular excitatory amino acids and failure of energy metabolism are two conditions associated with brain ischemia. In the present study we have combined the simultaneous inhibition of glutamate uptake and mitochondrial electron transport chain to simulate neuronal damage associated with brain ischemia. Results show that cerebellar granule neurons are not vulnerable to transient glutamate uptake inhibition by L-trans-pyrrolidine-2,4-dicarboxylate (PDC) despite the increase in the extracellular concentration of glutamate, unless they are simultaneously exposed to the mitochondrial toxins 3-nitropropionic acid (3-NP) or sodium azide. Cell damage was assessed by light microscopy observation, by reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and by the fluorescent markers for live and dead cells, calcein and ethidium homodimer, respectively. The protective effect of alternative energy substrates, such as pyruvate, acetoacetate, and beta-hydroxybutyrate against PDC-induced neuronal death during 3-NP exposure was studied and compared to the effects of the antioxidant vitamin E, the spin trapper alpha-phenyl-N-tert-butylnitrone (PBN), voltage-dependent calcium channel antagonists, and glutamate receptor antagonists. Results show that neuronal damage can be efficiently prevented in the presence of pyruvate and the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801, whereas the non-NMDA receptor antagonist NBQX, acetoacetate, vitamin E, and PBN showed partial protection. In contrast, beta-hydroxybutyrate and voltage-dependent calcium channels blockers did not show any protective effect at the concentrations tested.