The subjective feeling of a gap between conceptual and perceptual fluency is interpreted as a metacognitive signal of pastness.

The present study aimed to address the following question: does the discrepancy between an expected word and its readability enhances or impair its memorability? We used an adaptation of the sentence stem paradigm (Whittlesea in J Exp Psycol 19:1235-1253, 1993) and manipulated the perceptual clarity of the words by introducing some Gaussian noise (Reber in Psycol Sci 9:45-48, 1998). The target words were semantically predictable or otherwise (conceptual fluency) or were easy or difficult to read (perceptual fluency). The first experiment was conducted to ensure that the two manipulated factors had an impact on the readability of the words. In particular, results showed that when the words were written against a noisy background their predictability enhanced the judgement of readability. The second experiment aimed to test the hypothesis that recognition would be influenced by the discrepancy between conceptual and perceptual fluency. The results showed that with a noisy background, the predictability of the target words had an impact on recognition judgement; with a clear background, the effect on the recognition judgement was caused by the non-predictability of the target words. Conversely, confidence in judgement increased when the two factors went in the same direction, that is, predictability with clarity and non-predictability with low clarity. The results showed that (a) depending on the task, the effects of conceptual and perceptual fluency did not go in the same direction; (b) the kinds of fluency (conceptual and perceptual) were not independent; and (c) recognition judgements were affected by the gap between conceptual and perceptual fluency.

The clinical utility of PGD with HLA matching: a collaborative multi-centre ESHRE study.

STUDY QUESTION: Has PGD-HLA been successful relative to diagnostic and clinical efficacy? SUMMARY ANSWER: The diagnostic efficacy of PGD-HLA protocols was found lower in this study in comparison to published PGD-HLA protocols and to that reported for general PGD by ESHRE (78.5 vs 94.1% and vs 92.6%, respectively), while the clinical efficacy has proven very difficult to assess due to inadequate follow-up of both the ART/PGD and HSCT procedure outcomes. WHAT IS KNOWN ALREADY: The first clinical cases for PGD-HLA were reported in 2001. It is now a well-established procedure, with an increasing number of cycles performed every year. However, PGD-HLA is still offered by relatively few PGD centres, the currently available data is fragmented and most reports on PGD-HLA applications are limited in number and scope. Published systematic details on methodology, diagnostic results, overall ART success and haematopoietic stem cell transplantation (HSCT) outcomes are limited, precluding an evaluation of the true clinical utility of PGD-HLA cycles. STUDY DESIGN, SIZE, DURATION: This retrospective multi-centre cohort study aimed to investigate the diagnostic and clinical efficacy of the PGD-HLA procedure and the aspects of PGD-HLA cycles influencing positive outcomes: birth of genetically suitable donor-baby (or babies) and HSCT. In April 2014, 32 PGD centres (Consortium members and non-members) with published/known PGD-HLA activity were invited to participate. Between February and September 2015, 14 centres submitted their data, through a custom-designed secure database, with unique login access for each centre. Data parameters covered all aspects of PGD-HLA cycles (ART, embryology and genetic diagnosis), donor-babies born and HSCT. PARTICIPANTS/MATERIALS, SETTING, METHODS: From 716 cycles submitted by 14 centres (performed between August 2001 and September 2015), the quality evaluation excluded 12 cycles, leaving 704, from 364 couples. The online database, based on REDCap, a free, secure, web-based data-capture application, was customized by Centre for Clinical Epidemiology and Outcomes Research (CLEO), Athens. Continuous variables are presented using mean, standard deviation, median and interquartile range, and categorical variables are presented as absolute and relative frequencies. MAIN RESULTS AND THE ROLE OF CHANCE: The data included 704 HLA-PGD cycles. Mean maternal age was 33.5 years. Most couples (81.3%) requested HLA-typing with concurrent exclusion of a single monogenic disease (58.6% for beta-thalassaemia). In 92.5% couples, both partners were fertile, with an average 1.93 HLA-PGD cycles/couple. Overall, 9751 oocytes were retrieved (13.9/cycle) and 5532 embryos were analysed (7.9/cycle). Most cycles involved fresh oocytes (94.9%) and Day 3 embryo biopsy (85.3%). In 97.5% of cycles, the genotyping method involved PCR only. Of 4343 embryos diagnosed (78.5% of analysed embryos), 677 were genetically suitable (15.4% of those analysed for HLA alone, 11.6% of those analysed for HLA with exclusion of monogenic disease). Of the 364 couples, 56.6% achieved an embryo transfer (ET) and 598 embryos were transferred in 382 cycles, leading to 164 HCG-positive pregnancies (pregnancy rate/ET 41.3%, pregnancy rate/initiated cycle 23.3%) and 136 babies born (live birth rate/ET 34.3%, live birth rate/initiated cycle 19.3%) to 113 couples. Data analysis identified the following limitations to the overall success of the HLA-PGD procedure: the age of the mother undergoing the treatment cycle, the number of oocytes collected per cycle and genetic chance. HSCT was reported for 57 cases, of which 64.9% involved combined umbilical cord-blood and bone marrow transplantation from the HLA-identical sibling donor; 77.3% of transplants reported no complications. LIMITATIONS REASONS FOR CAUTION: The findings of the study may be limited as not all PGD centres with PGD-HLA experience participated. Reporting bias on completion of the online database may be another potential limitation. Furthermore, the study is based on retrospective data collection from centres with variable practices and strategies for ART, embryology and genetic diagnosis. WIDER IMPLICATIONS OF THE FINDINGS: This is the first multi-centre study evaluating the clinical utility of PGD-HLA, indicating variations in practice and outcomes throughout 15 years and between centres. The study highlights parameters important for positive outcomes and provides important information for both scientists and couples interested in initiating a cycle. Above all, the study underlines the need for better collaboration between all specialists involved in the ART-PGD/HLA procedure, as well as the need for comprehensive and prospective long-term data collection, and encourages all specialists to aim to properly evaluate and follow-up all procedures, with the ultimate aim to promote best practice and encourage patient informed decision making. STUDY FUNDING/COMPETING INTEREST(S): The study wishes to acknowledge ESHRE for funding the customization of the REDCap database. There are no competing interests. TRIAL REGISTRATION NUMBER: N/A.

CRISPR-on system for the activation of the endogenous human INS gene.

Advances in the field of epigenetics have allowed the design of new therapeutic strategies to address complex diseases such as type 1 diabetes (T1D). Clustered regularly interspaced short palindromic repeats (CRISPR)-on is a novel and powerful RNA-guided transcriptional activator system that can turn on specific gene expression; however, it remains unclear whether this system can be widely used or whether its use will be restricted depending on cell types, methylation promoter statuses or the capacity to modulate chromatin state. Our results revealed that the CRISPR-on system fused with transcriptional activators (dCas9-VP160) activated endogenous human INS, which is a silenced gene with a fully methylated promoter. Similarly, we observed a synergistic effect on gene activation when multiple single guide RNAs were used, and the transcriptional activation was maintained until day 21. Regarding the epigenetic profile, the targeted promoter gene did not exhibit alteration in its methylation status but rather exhibited altered levels of H3K9ac following treatment. Importantly, we showed that dCas9-VP160 acts on patients' cells in vitro, particularly the fibroblasts of patients with T1D.

Mesenchymal stromal cells overexpressing vascular endothelial growth factor in ovine myocardial infarction.

Mesenchymal stromal cells (MSCs) are cardioprotective in acute myocardial infarction (AMI). Besides, we have shown that intramyocardial injection of plasmid-VEGF(165) (pVEGF) in ovine AMI reduces infarct size and improves left ventricular (LV) function. We thus hypothesized that MSCs overexpressing VEGF(165) (MSCs-pVEGF) would afford greater cardioprotection than non-modified MSCs or pVEGF alone. Sheep underwent an anteroapical AMI and, 1 week later, received intramyocardial MSCs-pVEGF in the infarct border. One month post treatment, infarct size (magnetic resonance) decreased by 31% vs pre-treatment. Of note, myocardial salvage occurred predominantly at the subendocardium, the myocardial region displaying the largest contribution to systolic performance. Consistently, LV ejection fraction recovered to almost its baseline value because of marked decrease in end-systolic volume. None of these effects were observed in sheep receiving non-transfected MSCs or pVEGF. Although myocardial retention of MSCs decreased steeply over time, the treatment induced significant capillary and arteriolar proliferation, which reduced subendocardial fibrosis. We conclude that in ovine AMI, allogeneic VEGF-overexpressing MSCs induce subendocardial myocardium salvage through microvascular proliferation, reducing infarct size and improving LV function more than non-transfected MSCs or the naked plasmid. Importantly, the use of a plasmid rather than a virus allows for repeated treatments, likely needed in ischemic heart disease.

Donor Age Influences Graft-Versus-Host Disease Relapse-Free Survival after Allogeneic Stem Cell Transplant in Elderly Patients in Two Countries from Latin America.

BACKGROUND AND OBJECTIVES: Allogeneic stem cell transplantation (Allo-SCT) in elderly patients is a growing practice. We aimed to determine the graft-versus-host disease (GVHD) relapse-free survival (GRFS) in patients ≥65 years who underwent Allo-SCT in two countries from Latin America. PATIENTS AND METHODS: We performed a retrospective analysis of patients ≥65 years who underwent Allo-SCT in Argentina and Brazil from 2007 to 2019. RESULTS: Ninety-eight patients were evaluated, with primary diagnoses of acute myeloid leukemia and myelodysplastic syndrome; 30% of patients had a hematopoietic cell transplant-comorbidity index (HCT-CI) score ≥3 and 49% were in complete remission. Donor types included matched sibling (n = 41), matched unrelated (n = 31), and haploidentical (HID; n = 26) donors. The conditioning regimen was myeloablative in 28 patients (14 busulfan pharmacokinetically [PK]-guided) and reduced-intensity in 70 patients. The two-year non-relapse mortality (NRM) was 29%, with a higher NRM in melphalan-based compared to other conditionings (51% vs. 33%, p = 0.02). The two-year relapse rate was 24%, with a reduction in PK-guided busulfan (0% vs. 28%, p = 0.03). The two-year overall survival (OS) and GRFS was 52% and 38%, respectively, with a significant reduction in GRFS in HCT-CI ≥3 (27% vs. others 42%, p = 0.02) and donors ≥40 years (29% vs. <40 years 55%, p = 0.02). These variables remained significantly associated with GRFS after multivariate analysis. CONCLUSION: In this cohort of elderly patients from Argentina and Brazil undergoing Allo-SCT, donor age and comorbidities significantly influenced GRFS. The role of the conditioning regimen in this population deserves further investigation.

Evaluating the Use of a CPOE for Chemotherapy Protocols.

Chemotherapy drugs are one of the most common causes of serious and fatal medication errors, especially during prescribing, where computerized physician order entry (CPOE) take on importance. This study proposes the description of the post-implementation status of a CPOE in a highly specialized hospital between January and June 2018, among patients older than 18 years. Results: a total of 8835 protocols were indicated using the specific CPOE (93% use rate over all protocols) 91% completed the administration, 1.2% were rejected by pharmacy, and 6.8% was canceled. The most frequent cause of rejection by pharmacy and cancellation by oncologist was an inadequate dose. Most of the protocols indicated using the CPOE implemented, with a reject by pharmacy rate of 1.2%, indicates the utility of CPOE as an error prevention strategy.

Challenges of In-House Development and Implementation of a CPOE for Oncology.

Hospital Italiano de Buenos Aires (HIBA) is an academic tertiary care hospital highly specialized that has started the process of informatization of chemotherapy protocols. The objective is to describe the development of a computerized physician order entry (CPOE) oriented to the oncology adult patient and the members of the healthcare team that works with him (physicians, pharmacists, nurses and administrative staf) to improve the process and prevent errors at a critical point in the patient's health care: during prescription, preparation and / or administration. The development of this system consisted of several stages: inquiries about the usual work and perception of needs of the potential users; user-centered design; interoperability with the electronic health record (EHR) and development of a final prototype.

Changes in Corneal Expression of MUC5AC after Autologous Serum Eyedrop Treatment in Patients with Limbal Stem Cell Deficiency.

Purpose: To evaluate the effect of autologous serum eyedrops treatment on corneal expression of the MUC5AC in patients with limbal deficiency. Methods: A prospective and comparative interventional case series study of 42 eyes of 21 patients was performed before and 8 weeks after treatment with autologous serum. All patients underwent a complete ophthalmic assessment of the tear film and ocular surface, corneal impression cytology (IC) and MUC5AC detection by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Results: Forty-one of the 42 eyes studied were available for both conventional cytology and MUC5AC analysis prior to and after treatment. Differences between outcomes obtained by impression cytology and MUC5AC detection were found in 9 of 82 samples (11%). We found changes in the corneal expression of MUC5AC after treatment in 19 of 41 eyes (46.3%): 18 of them (94.7%) changed from positive to negative expression, and 1 eye (5.3%) changed from negative to positive MUC5AC expression after autologous serum eyedrops. These changes were related with the corneal involvement prior to treatment (15 of them (78.9%) occurred in patients with slight corneal involvement), and with the improvement in the degree of squamous metaplasia after treatment (P = .001 and P = .003, respectively). Conclusions: The treatment significantly improved tear stability, squamous metaplasia, and subjective patient perception. Autologous serum eyedrops treatment diminished the corneal expression of MUC5AC mainly in patients with slight corneal involvement before treatment.

[Pathophysiology of the glutamate and the glycine transporters: new therapeutic targets]. / Fisiopatologia de los transportadores de glutamato y de glicina: nuevas dianas terapeuticas.

INTRODUCTION: The amino acids glutamate and glycine, apart from their role in protein synthesis, are two fundamental neurotransmitters in the central nervous system of mammals. The first one is ubiquitous and is involved in excitatory pathways of the neocortex, the retina and the cerebellum, and the second is involved in inhibitory pathways of brain caudal areas. However, both share their way of acting by integrating into the functioning of glutamate receptors of the NMDA type fundamentals in the regulation of motor, sensory and cognitive systems. AIM: To highlight the need for a fine regulation of glutamate and glycine concentrations in the intracellular and extracellular spaces of the nervous system through the action of very specific transporters for both neurotransmitters located in the plasma membrane of neurons and glial cells. DEVELOPMENT: The role of the glutamate and glycine transporters in glutamatergic and glycinergic neurotransmission and in the functioning of the nervous system is described. The pathological consequences of imbalances in these signaling pathways are pointed out. We also describe its involvement in pathologies such as schizophrenia, chronic pain, cerebral ischemia, diseases such as hereditary hyperekplexia and the non-ketotic hyperglycinemia, and neurodegenerative disorders. CONCLUSIONS: The knowledge at molecular level of the way of acting of these transporters for glutamate and glycine is allowing the identification and development of new therapeutic strategies for pathologies such as those described above and the development of new drugs.

TITLE: Fisiopatologia de los transportadores de glutamato y de glicina: nuevas dianas terapeuticas.Introduccion. Los aminoacidos glutamato y glicina, aparte de su papel en la sintesis de proteinas, son dos neurotransmisores fundamentales en el sistema nervioso central de los mamiferos. El primero es ubicuo y esta implicado en vias excitatorias de la neocorteza, la retina y el cerebelo, y el segundo esta asociado a vias inhibitorias de zonas caudales del cerebro. Sin embargo, ambos comparten su manera de actuar al integrarse en el funcionamiento de los receptores de glutamato del tipo NMDA, fundamentales en la regulacion de sistemas motores, sensitivos y cognitivos. Objetivo. Evidenciar la necesidad de una regulacion exquisita de las concentraciones de glutamato y de glicina en los espacios intra y extracelulares del sistema nervioso mediante la actuacion de transportadores muy especificos para ambos neurotransmisores localizados en la membrana plasmatica de las neuronas y de las celulas de la glia. Desarrollo. Se describe el papel de los transportadores de glutamato y glicina en la neurotransmision glutamatergica y glicinergica, y en el funcionamiento del sistema nervioso. Se señalan las consecuencias patologicas de los desequilibrios en estas vias de señalizacion. Tambien se describe su participacion en patologias como la esquizofrenia, el dolor cronico, la isquemia cerebral, la hiperplexia hereditaria, la hiperglicinemia no cetosica o trastornos neurodegenerativos. Conclusiones. El conocimiento de la forma molecular de actuar de los transportadores de glutamato y de glicina esta permitiendo la identificacion y el desarrollo de nuevas estrategias terapeuticas para patologias como las descritas y el desarrollo de nuevos farmacos.

An open multicenter phase II trial of docetaxel-gemcitabine in Charlson score and performance status (PS) selected elderly patients with stage IIIB pleura/IV non-small-cell lung cancer (NSCLC): the GFPC 02-02a study.

UNLABELLED: The aim of this study was to determine the impact of patient selection based on age, comorbidity and performance status on the efficacy of platinum-free combination therapy on non-small-cell lung cancer after 65 years of age. We analyzed the overall response rate, the median survival time, the 1-year survival rate, toxicity and quality of life after one to three 6-week cycles of docetaxel 30mg/m(2) weekly and gemcitabine 900mg/m(2) at weeks 1, 2, 4 and 5. Fifty patients (median age 73.7 years) were eligible. The mean number of comorbid conditions per patient was 0.8 [Balducci L. Lung cancer and aging. ASCO 2005. Educational book. p. 587-91; Piquet J, Blanchon F, Grivaux M, et al. Primary bronchial carcinoma in elderly subjects in France. Rev Mal Respir 2003;20:691-9; Jatoi A, Hillman S, Stella P, et al. Should elderly non-small-cell lung cancer patients be offered elderly-specific trials? Results of a pooled analysis from the North Central Cancer Treatment Group. J Clin Oncol 2005;23:9113-9; Balducci L, Extermann M. Management of cancer in the older person: a practical approach. Oncologist 2000;5:224-37]. Forty-five patients were assessable: 17 (34%) had an objective response, 18 (36%) had stable disease and 10 progressed (20%). The median survival time was 7 months and the 1-year survival rate 23.5%. The main grade III-IV adverse event was neutropenia (32% of patients). CONCLUSION: Platinum-free dual-agent chemotherapy gives similar results in patients over 65, selected on the basis of their precise age and comorbidity, to that reported in younger subjects.

Fibrohistiocitoma maligno / Malignant fibrohystiocytoma

RESUMEN El fibrohistiocitoma maligno es el sarcoma de partes blandas más frecuente en adultos; es poco frecuente como tumor primario cutáneo. Presenta predilección por el sexo masculino con una mayor incidencia entre la quinta y sexta década de la vida. Se localiza predominantemente en las extremidades. Presentamos a continuación el caso clínico de un paciente con diagnóstico de fibrohistiocitoma maligno localizado en hallux de pie derecho y realizaremos una revisión de la literatura.

ABSTRACT Malignant fibrohistiocytoma is the most frequent soft tissue tumor in adults; it is rare as a primary cutaneous tumor. It presents a predilection for males with the highest incidence between the fifth and sixth decade of life. It is located predominantly on the extremities. We will perform a literature review. We present below the clinical case of a patient diagnosed with malignant fibrohistiocytoma located in hallux of the right foot.

Transverse Cervicothoracic Stabbing: Multidisciplinary Management of a Surgical Emergency.

Tracheobronchial injuries are closely related to orotracheal intubations and chest traumas. Stabbing injuries are very rare and often life threatening because of the damage to vital structures such as the respiratory tract and large arterial or venous vessels. Early diagnosis and treatment of penetrating neck injuries increase survival rates. We report a case of the tracheobronchial section with a penetrating stabbing wound on the left laterocervical area associated with contralateral pneumothorax, requiring urgent surgical pulmonary repair, tracheal suture, and tracheotomy. Prompt action with a multidisciplinary approach resulted in a favorable outcome.

Genetics of recurrent miscarriage and fetal loss.

Despite years of research, miscarriage, particularly when recurrent, continues to pose a medical challenge. An embryo chromosomal error is responsible for 50-60% of recurrent cases; however, up to 30-50% remains an enigma. Successful pregnancy involves different maternal physiologic changes and certain complex interactions between the fetus and the mother by cytokines, angiogenic mediators and hormones. To date, research lines have focused on genetic and epigenetic polymorphisms related mainly to immune response and inflammatory mediators, and have yielded a significant relationship between recurrent miscarriage and immune mechanisms. Thus, unknown causes of miscarriage could be due to an immune imbalance induced by T-helper Th1/Th2/Th17 cytokines and regulatory T cells. Furthermore, these genes and mediators have long been suspected of being blood markers for the clinical diagnosis and management of miscarriage; however, more evidence is required for them to be included in medical practice and obstetric guidelines.

[Neuropsychological impairment in patients with intracranial aneurysms: surgical versus endovascular treatment]. / Alteraciones neuropsicológicas en pacientes con aneurismas cerebrales: tratamiento quirúrgico versus tratamiento endovascular.

OBJECTIVES: To describe the neuropsychological status of patients with intracranial aneurysms and to compare the cognitive status of patients with intracranial aneurysm treated by surgical or endovascular methods. MATERIAL AND METHODS: Ninety-three cases with intracranial aneurysms treated with surgery (n = 56) or embolization (n = 37) were included. A neuropsychological assessment was applied to both groups retrospectively, at least one year after treatment. RESULTS: Neuropsychological impairment was found in both groups. 35.7% of the patients treated with surgery and 43.2%, of those treated with embolization did not show any cognitive impairment. Visual Memory and Cued Recall of verbal information are better in patients treated by embolization. CONCLUSIONS: Our results show that a large proportion of patients with intracranial aneurysms have cognitive impairment after treatment. Endovascular management may cause less impairment in visual and verbal memory. However, bleeding may be the most important factor to explain these cognitive impairments.

Gran feto acardio: diagnóstico tardío de gestacion gemelar monocorial biamniótica complicada por secuencia TRAP: reporte de un caso y revisión de la literatura / Great acardiac fetus: late diagnosis of monochorionic diamniotic twin pregnancy complicated by sequence TRAP: case report and review of the literature

OBJETIVOS: reportar el caso de una paciente con gestación gemelar monocorial-biamniótica complicada por secuencia TRAP que dio lugar al nacimiento de un feto bomba de 1932 gramos sin malformaciones anatómicas y de un feto acardio anceps de 1800 gramos, y realizar una revisión sobre esta patología y la importancia de su diagnóstico y tratamiento precoces. MATERIALES Y MÉTODOS: se presenta el caso de un feto acardio en una gestante con embarazo sin control estricto en el Hospital San Pedro de Logroño en el año 2019, de interés por su diagnóstico tardío y elevado peso al nacimiento del feto acardio. Se realizó una búsqueda de la literatura en las bases de datos Medline vía PubMed, OVID, Embase y SciE-LO con las palabras clave DeCS y términos MeSH. Como criterios de inclusión se consideraron artículos tipo series y reportes de casos y artículos de revisión desde enero de 1950 hasta enero de 2020. RESULTADOS: la búsqueda incluyó 39 referencias bibliográficas sobre las que se repasaron las principales cuestiones teóricas a exponer. El peso del feto acardio de nuestro caso fue muy elevado sin provocar repercusión en el feto sano, en comparación con la bibliografía, lo que aporta singularidad al caso, siendo sólo equiparable la serie de casos de Brassard et al (1999), con pesos de los fetos acardio por encima de 1700 gramos y diferenciándose en 100 gramos del feto bomba. CONCLUSIONES: el feto acardio es una complicación infrecuente de embarazos gemelares monocoriales. Se requiere la presencia de anastomosis vasculares placentarias entre ambas circulaciones. El diagnóstico precoz es importante para disminuir la morbilidad y usar, en la medida de lo posible, técnicas terapéuticas no invasivas.

OBJECTIVES: to report the case of a patient with a monochorionic-biamniotic twin gestation complicated by TRAP sequence that gave rise to the birth of a pump fetus without anatomical malformations (1932 g) and an acardiac anceps fetus (1800 g), and to review this pathology and the importance of its early diagnosis and management. MATERIAL AND METHODS: the case of an acardiac fetus is presented in a pregnant woman without strict control at the Hospital San Pedro de Logroño in 2019, worthwhile because of its late diagnosis and high birth weight. A search of the literature was carried out in the Medline databases via PubMed, OVID, Embase and SciELO with the MeSH terms. As inclusion criteria, we considered series-type articles and case reports, cohorts and review articles from January 1950 to January 2020. RESULTS: 39 bibliographic references were included with the main theoretical questions to be reviewed. Our acardiac fetus weight was very high comparing with the bibiography and without causing repercussion in the healthy fetus, which contributes to the uniqueness of the case, only the series report by Brassard et al (1999) is comparable, with weights of the acardiac fetus above 1700 grams and differing by 100 grams from the pump fetus. CONCLUSIONS: the acardiac fetus is an infrequent complication of monochorionic twin pregnancies. The presence of placental vascular anastomoses between both circulations is required. Early diagnosis is important to decrease morbidity and to use, as far as possible, non-invasive therapeutic techniques.

Efflux and exchange of glycine by plasma membrane vesicles isolated from glioblastoma cells.

The efflux and exchange of glycine were studied in plasma membrane vesicles isolated from cultured glioblastoma cells. The mechanism of glycine translocation has been probed by comparing the ion dependence of net efflux to that of exchange. Dilution-induced efflux requires the simultaneous presence of internal sodium and chloride, while influx is dependent on the presence of these two ions on the outside (Zafra, F. and Giménez, C. (1986) Brain Res. 397, 108-116). Glycine efflux from the membrane vesicles is stimulated by external glycine, this exchange being dependent on external sodium, but not on external chloride. The parallelism observed in influx and efflux processes suggests that glycine is translocated in both directions across the membrane, probably by interacting with the carrier. To account for all the observed effects of external ions, glycine concentrations and membrane potential on glycine influx and efflux, a kinetic model of the Na+/Cl-/glycine cotransport system is discussed.

The role of chloride ions on the transport of glycine in plasma membrane vesicles from glial cells.

The high-affinity transport system for glycine in plasma membrane vesicles from C6 glioma cells is dependent on Na+ and also on the presence of Cl- in the incubation medium. This anion requirement is relatively specific for Cl-, since other anions are also capable of stimulating the glycine transport in the following order of decreasing efficacy: Cl- greater than Br- greater than SCN- congruent to I- greater than NO3- greater than F-. Chloride ions raise the Vmax for transport and, to a lesser extent, act on the Km. The data provided by direct measurements of the coupling of sodium and chloride to the transport of glycine by using a kinetic approach suggest a stoichiometry for the translocation cycle catalyzed by the glycine transporter of two sodium ions and one chloride ion per glycine zwitterion.

Efflux and exchange of glycine by synaptic plasma membrane vesicles derived from rat brain.

The influx and exchange of glycine were studied in synaptic plasma membrane vesicles isolated from rat brain. The vesicles were loaded with [U-14C]glycine by active transport driven by an Na+ as well as a Cl- gradient (out greater than in). Dilution-induced efflux requires the simultaneous presence of internal Na+ and Cl-. As the efflux of glycine has been demonstrated to be strictly dependent on the presence of both ions (Mayor, F., Jr., Marvizón, J.G., Aragón, M.C., Giménez, C. and Valdivieso, F. (1981) Biochem. J. 198, 535-541), it can be concluded that the efflux of glycine is, in many aspects, symmetrical with its influx. Glycine efflux from the membrane vesicles is stimulated by external glycine, this exchange being partially dependent on external sodium and not on external chloride. The parallelism observed in influx and efflux processes shows that the release of glycine (by efflux and homoexchange) occurs via the carrier system. These results suggest that glycine is translocated in both directions across the membrane, probably by interacting with the carrier. Both sodium and chloride have to be present on the same side as glycine.

Change of synaptic membrane lipid composition and fluidity by chronic administration of lithium.

The effect of chronic administration of lithium salts on the lipid composition and physical properties of the synaptosomal plasma membrane was examined in rat brain. The effect of lithium treatment has been studied on the fluorescence polarization of synaptosomal plasma membrane and artificial lipid vesicles and on the lipid composition of the membranes. Fluorescence polarization of lipophilic probes was used to study membrane lipid structure. Steady-state polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a probe of the hydrophobic core, was significantly lower in plasma membranes from lithium-treated animals. Altered DPH polarization was due to a decrease in the order parameter of the probe. The lithium-treatment also changed the fluorescence of 1-anilino-8-naphthalene sulfonate (ANS), a probe that binds to the polar head group of the phospholipids and to proteins on the membrane surface. Synaptic plasma membranes from treated rats presented no significant changes on the cholesterol-to-phospholipid ratio, although the phospholipid class distribution was altered and the membrane phospholipid unsaturation increased. In summary, the neural plasma membranes became disorder after chronic lithium administration at therapeutic levels. This structural change may be due to changes in plasma membrane phospholipid distribution and to the degree of unsaturation of phospholipid fatty acids.