Prediction of phosphenes occurrence in patients undergoing photon irradiation to ocular structures due to brain tumor.

BACKGROUND AND OBJECTIVE: Phosphenes are visual light phenomena that are experienced when there is no apparent light that stimulates the eye. In oncology, phosphenes are also present during radiation therapy for patients with tumors of the central nervous system, eyes, head and neck. Due to the discomfort of patients treated with irradiation to the head regions, research is conducted to determine whether the dose to the ocular structures is predictive for the occurrence of phosphenes. The objective was to demonstrate the relationship between the doses of the retina and vitreous humour with the appearance of phosphenes. MATERIAL AND METHOD: A descriptive study was carried out in a prospective cohort in 25 patients older than 18 years, with malignant tumours located at the level of the brain, both of primary and secondary origin, subjected to irradiation in 6 MV linear accelerators, during February 2020 to January 2021. As independent variables: Retinal dose and vitreous humour dose, and as dependent variables: Light flashes and stable light. Logistic regression analysis was used for prediction, using the SPSS statistical program (version 26.0). RESULT: A final date of 380 external radiotherapy treatments. The presence of any of the events in a prevalence of 58.7% of the total of fractions. The distribution for the presence of both events, flash of light and stable light, was 69.1%, 20.6% and 10.3% respectively. In the logistic regression analysis, for the light flare, only the dose factor in vitreous was significant (OR: 1.74, IC [1.059-2.419] p: 0.001). For stable light, the dose in the retina (OR: 1.73, IC [1.121-2.341] p: 0.005), and dose in the vitreous humor (OR: 1.82, IC [1.335-2.315] p: 0.003). CONCLUSIONS: There is a predictive relationship between the doses of irradiation of the retina and vitreous humour, for the generation of phosphenes. These results help radiotherapy centres take these anatomical structures into account to reduce the presence of phosphenes in patients. Likewise, it would help to reduce phosphenes, keeping the bunker area illuminated during the treatment.

Predicción de ocurrencia de fosfenos en pacientes sometidos a irradiación con fotones a estructuras oculares por tumor cerebral / Prediction of phosphenes occurrence in patients undergoing photon irradiation to ocular structures due to brain tumor

Antecedentes y objetivo Los fosfenos son fenómenos de luz visual que se experimentan cuando no hay luz aparente que estimule el ojo. En oncología, los fosfenos también están presentes durante la radioterapia para pacientes con tumores del sistema nervioso central, ojos, cabeza y cuello. Debido a la incomodidad de los pacientes tratados con irradiación en las regiones de la cabeza, se realiza investigación para determinar si la dosis en las estructuras oculares son predicción para la ocurrencia de fosfenos. El objetivo fue demostrar la relación entre las dosis de retina y humor vítreo con la aparición de fosfenos. Material y método Se realizó un estudio descriptivo, en una cohorte prospectiva en 25 pacientes mayores de 18 años, con tumores malignos localizados a nivel de encéfalo, tanto de origen primario como secundario, sometidos a irradiación en aceleradores lineales de 6MV, durante febrero 2020 a enero del 2021. Como variables independientes: dosis a retina y dosis a humor vítreo, y como variables dependientes: destellos de luz y luz estable. Para la predicción se utilizó el análisis de regresión logística, mediante el programa estadístico SPSS® versión 26.0. Resultado Una data final de 380 tratamientos de radioterapia externa. La presencia de cualquiera de los eventos en un predominio del 58,7% del total de fracciones. La distribución por la presencia de ambos eventos, destello de luz y luz estable, fue del 69,1, 20,6 y 10,3%, respectivamente. En el análisis de regresión logística, para el destello de luz, solo fue significativo el factor de dosis en vítreo (OR: 1,74; IC 95%: 1,059-2,419; p: 0,001). Para la luz estable, fueron significativos la dosis en retina (OR: 1,73; IC 95%: 1,121-2,341; p: 0,005) y dosis en humor vítreo (OR: 1,82; IC 95%: 1,335-2,315; p: 0,003). Conclusiones Existe una relación predictiva entre las dosis de irradiación de la retina y del humor vítreo, para la generación de fosfenos (AU)

Background and objective Phosphenes are visual light phenomena that are experienced when there is no apparent light that stimulates the eye. In oncology, phosphenes are also present during radiation therapy for patients with tumors of the central nervous system, eyes, head and neck. Due to the discomfort of patients treated with irradiation to the head regions, research is conducted to determine whether the dose to the ocular structures is predictive for the occurrence of phosphenes. The objective was to demonstrate the relationship between the doses of the retina and vitreous humor with the appearance of phosphenes. Material and method A descriptive study was carried out in a prospective cohort in 25 patients older than 18 years, with malignant tumors located at the level of the brain, both of primary and secondary origin, subjected to irradiation in 6MV linear accelerators, during February 2020 to January 2021. As independent variables: Retinal dose and vitreous humor dose, and as dependent variables: Light flashes and stable light. Logistic regression analysis was used for prediction, using the SPSS statistical program (version 26.0). Result A final date of 380 external radiotherapy treatments. The presence of any of the events in a prevalence of 58.7% of the total of fractions. The distribution for the presence of both events, flash of light and stable light, was 69.1%, 20.6% and 10.3% respectively. In the logistic regression analysis, for the light flare, only the dose factor in vitreous was significant (OR: 1.74; 95% CI: 1.059-2.419; p: 0.001). For stable light, the dose in the retina (OR: 1.73; 95% CI: 1.121-2.341; p: 0.005), and dose in the vitreous humor (OR: 1.82; 95% CI: 1.335-2.315; p: 0.003). Conclusions There is a predictive relationship between the doses of irradiation of the retina and vitreous humor, for the generation of phosphenes (AU)

Demographic and social profile of epilepsy in a vulnerable low-income population in Bogotá, Colombia. / Perfil demográfico y social de la epilepsia en una población vulnerable y de bajos recursos económicos en Bogotá, Colombia.

INTRODUCTION: Very few studies describe the demographic and social profile of epilepsy in vulnerable low-income populations. METHODS: Observational, descriptive, cross-sectional study prospectively recording data from all patients diagnosed with epilepsy who attended a specialist neurology consultation between January and March 2014. Data were analysed using descriptive epidemiology tools. RESULTS: A total of 107 patients were evaluated, of whom 24.2% were illiterate and only 10.2% had completed a higher education programme. Most of the patients (86.8%) had a low socioeconomic status; 73.8% were single and 76.7% were unemployed. The main risk factors for epilepsy in this population were recorded as follows: delayed psychomotor development (n=24, 22.4%), head trauma (n=16, 14.9%), and central nervous system infection (n=13, 12.1%). Most patients (70.1%) responded to antiepileptic drugs (controlled cases) and 15.4% (n=15) had drug-resistant epilepsy (refractory cases). CONCLUSION: The demographic and clinical profiles of the patients included in this study resemble those published for high-income populations; differences are mostly limited to aetiological classification and risk factors. The social profile of the patients evaluated in this study shows high rates of unemployment, illiteracy, and single marital status. These findings seem to be more frequent and prevalent in this group than in high income populations.

Desensitization of beta-adrenergic responses in adipocytes involves receptor subtypes and cAMP phosphodiesterase.

Acute exposure of isolated adipocytes to isoproterenol induces the desensitization of lipolytic responses to norepinephrine and selective beta 1-, beta 2- and beta 3-adrenoceptor agonists, as well as the adrenocorticotropic hormone 1-24 fragment (ACTH). Forskolin and 8-bromo-cAMP responses are also desensitized. When lipolysis was measured in the presence of OPC 3911 [N-cyclohexyl-N-2-hydroxyethyl-4(6-(1,2-dihydro-2- oxoquinolyloxy))butyramide], a specific inhibitor of the cAMP phosphodiesterase of adipocytes, the desensitization of all lipolytic agents--except the beta 2-adrenoceptor agonist--was abolished. Isoproterenol induced a similar loss (35%) of both membrane beta 1- and beta 2-adrenoceptors and an uncoupling of beta 1-adrenoceptors, but did not modify the weak coupling of control beta 2-adrenoceptors. These data suggest that isoproterenol induced (i) an activation of the cAMP phosphodiesterase, which is solely responsible for the desensitization of norepinephrine response as well as beta 1- and beta 3-adrenoceptor mediated responses and (ii) an additional desensitization of the sole beta 2-adrenergic signaling system which suggests a subtype-selective pattern of regulating processes.

Theoretical approaches to D-amino acid oxidase.

Several substrates and roles have been proposed for D-amino acid oxidase (E.C. 1.4.3.3.); however, there is no proof that they possess the required characteristics to account for the ubiquity, large amounts and great activity of the enzyme as found in diverse cells and tissues. Based on the similar stereoposition of identically charged atoms and lateral side chain (R) with respect to the alpha-hydrogen atoms in beta-sheet conformation and in D-amino acids, it is proposed that its substrates may include several membrane-related proteins, partially in beta-sheet conformation, whose alpha-hydrogen atoms would be the real object of D-amino acid oxidase catalysis. A monooxygenase-like enzymatic activity of D-amino acid oxidase with these novel substrates is considered, for which the final products are hypothesized to be protein alpha-carbon hydroxyls resulting from the incorporation of one atom of oxygen into the substrate, the other being reduced to water. Alternatively, it is also proposed that D-amino acid oxidase (and possibly other monooxygenase enzymes) would have a hydroperoxide-synthetase activity. In this case, protein alpha-carbon hydroperoxide and not water, but another reduced molecule, would be the final products. The new enzymatic performances of D-amino acid oxidase and the possible role of its potential final products in redox and other biochemical processes are discussed.

Disminucion de la captacion de H3-GABA en cerebelo de ratas intoxicadas con manganeso. / Determination of 3H-GABA binding in cerebellun of rats with chronic manganese poisoning

En ratas intoxicadas por via oral durante 8 meses con manganeso en concentraciones de 1 y 5 mg/ml de agua de bebida, se produjo una disminucion en la captacion especifica de H3-GABA en el cerebelo

Fijacion de H3-GABA por el cerebelo de ratas infectadas con el virus de la encefalitis equina venezolana. / H3 GABA binding by the cerebellum of rats infected with the Venezuelan equine encephalitis virus

La infeccion por el virus de la Encefalitis Equina Venezolana produjo un aumento significativo en el numero de sitios de fijacion del H3-GABA en el cerebelo.La infeccion tambien causo una disminucion en la afinidad de estos receptores por GABA

Pituitary response to a dopamine antagonist at different times of the day in normal women.

In order to determine whether or not pituitary responsiveness to the dopaminergic antagonist clebopride changes during the nyctohemeral cycle, 10 healthy women with regular cycles were given 1 mg of clebopride orally at 09.00 h and 24.00 h with at least a 5 day interval between each test. In addition, 5 of the women were given a placebo instead of clebopride at midnight to evaluate the spontaneous hormonal changes. During the 24.00 h test the women had significantly higher (P less than 0.05) mean TSH basal levels. Serum prolactin (Prl) increased significantly (P less than 0.001) after clebopride administration while these changes did not occur when placebo was used instead of clebopride at midnight. The Prl response to clebopride was qualitatively similar at 09.00 h and at 24.00 h. Clebopride given at midnight induced a significant increase (P less than 0.05) in serum TSH while this change did not occur when the drug was given at 09.00 h or when placebo was given at midnight. The administration of clebopride resulted in no discernible alternations in serum LH, FSH or GH in either the 09.00 h or the 24.00 h tests. Thus, Prl responses to clebopride were similar in the morning and at midnight, TSH significantly increased after clebopride at midnight whereas this did not occur when the drug was given in the morning, and no significant changes were induced in LH, FSH or GH at the times studied.