Determining factors of pulse oximetry accuracy: a literature review.

OBJECTIVE: Identify and reach consensus on the variables that affect the measurement of oxygen saturation using pulse oximetry. METHODS: We applied inclusion and exclusion criteria to select relevant studies in databases such as Ebsco and PubMed. The search strategies, carried out until December 2023, focused on publications that addressed the technology of pulse oximeters and variables that influence their accuracy. We assessed the risk of bias of the included studies and used standardized methods for synthesis of results. RESULTS: 23 studies were included. The synthesis of the results highlighted that equipment with tetrapolar technology showed greater precision in oxygen saturation measurements. Increased skin pigmentation, hemoglobinopathies and high skin temperatures can lead to an overestimation of SpO2, while factors such as low perfusion, cold skin temperature, nail polish or tattoos, hypoxemia, anemia and high altitude training, they may underestimate it. On the other hand, motion artifacts, light pollution, frequency >150 beats per minute, electromagnetic interference and location of the sensor can cause distortion of the photoplethymography signal. CONCLUSIONS: The synthesis of the results highlighted that skin pigmentation and light interference can lead to an overestimation of SpO2, while other factors such as low perfusion and altitude tend to underestimate it. The studies presented variability and heterogeneity in their designs, evidencing limitations in the consistency and precision of the evidence. Despite these limitations, the results underscore the importance of considering multiple variables when interpreting pulse oximetry measurements to ensure their reliability. The findings have significant implications for clinical practice and future research.

Willingness toward post-mortem body donation to science at a Mexican university: an exploratory survey.

BACKGROUND: Voluntary post-mortem donation to science (PDS) is the most appropriate source for body dissection in medical education and training, and highly useful for biomedical research. In Mexico, unclaimed bodies are no longer a legal source, but PDS is legally possible, although scarcely facilitated, and mostly ignored by the general population. Therefore, we aimed to evaluate the attitude and willingness for PDS and to identify a sociodemographic profile of people with willingness toward PDS. METHODS: A validated on-line survey was distributed by the convenience method via the social networks of a Catholicism-inspired, private university in northern Mexico. Frequency analyses of all variables and coded free comments were complemented with association studies. RESULTS: Although the responder cohort (n = 143) was too small and biased to be representative of the university community (n = 13,500), willingness to post-mortem organ donation was 90.7% and to PDS 70.7%. In this cohort, PDS willingness had the strongest association with mature age (> 40 years old; P, 0.0008). Among young adults, willingness to PDS was the lowest among volunteers from technical and business schools and the highest among those from the social sciences (P, 0.009). Respondents from the social sciences were also the most consistent between attitude and behavior with respect to organ donation. A free comment option revealed respondents were interested in the unusual taboo topic. CONCLUSIONS: A small, but sufficiently large proportion expressed willingness toward PDS. In our university cohort, which was biased in higher education and altruism, mature age and social interest were associated with PDS willingness.

Daño vascular y rendimiento cognitivo-funcional en una población con deterioro cognitivo leve / Vascular damage and cognitive-functional performance in a population with mild cognitive impairment

Introducción: Existe evidencia de etapas predemenciales en la demencia vascular. La enfermedad de Alzheimer y el trastorno cognitivo vascular comparten mecanismos de riesgo comunes, y la comorbilidad vascular puede estar presente en el 30-60% de los pacientes con enfermedad de Alzheimer. Este trabajo evalúa el impacto de la gravedad del daño vascular estructural según la clasificación de Fazekas en el desempeño cognitivo funcional en pacientes con deterioro cognitivo leve (DCL). Pacientes y métodos: Estudio de corte transversal de pacientes con DCL de 65 años o más con resonancia magnética cerebral. Se administró una batería neurocognitiva y la escala estudio funcional extendido (EFE) para evaluar la funcionalidad compleja. Los pacientes se clasificaron según Fazekas: 0-1, 2 y 3. Se realizó un análisis bivariado y un análisis multivariable. Resultados: Se incluyó a 346 pacientes, con una edad de 77,9 (desviación estándar: 6,1). El 66,2% presentó Fazekas 0-1; el 22,8%, Fazekas 2; y el 11%, Fazekas 3. La edad y el valor del Minimental State Examination se asociaron con un Fazekas más avanzado. El análisis multivariado mostró una asociación independiente entre el daño vascular y la alteración funcional compleja medida por el EFE. Conclusiones: La progresión del daño estructural a predominio de sustancia blanca afectaría al desempeño cognitivo global y a las tareas de función ejecutiva. El hallazgo más significativo fue la correlación del grado del daño vascular con el déficit de la funcionalidad compleja medida con herramientas clínicas que incluyeron recursos tecnológicos. Se resalta el valor clínico de identificar los individuos con demencia vascular prodrómica, ya que podría optimizar las medidas de prevención.(AU)

Introduction: There is evidence of predemential stages in Vascular Dementia (VD). Alzheimer Disease (AD) and VD share common risk factors and mechanisms. Vascular comorbility may present in 30-60% of patients with AD (mixed dementia). This work seeks to evaluate the impact of the severity of structural vascular damage according to the Fazekas classification (F) on functional cognitive performance in patients with Mild Cognitive Impairment (MCI). Patients and methods: A cross-sectional study of patients with MCI aged 65 years or older who had brain MRI was carried out. A neurocognitive battery and the EFE (Extended Functional Study) scale were administered to assess complex functionality. The patients were divided according to Fazekas classification: 0-1, 2 and 3. Bivariate analysis and multivariate analysis were performed. Results: 346 patients were included, age: 77.9 (SD 6.1). 66.2% presented F01, 22.8% F2 and 11% F3. Age and MMSE value were statistically significant. Multivariate analysis showed an independent association between vascular damage and complex functional alteration measured by EFE. Conclusions: In conclusion, the progression of structural damage to a predominance of white matter would affect global cognitive performance and tasks related to executive function. The most significant finding was the correlation of the degree of vascular damage with the deficit of complex functionality measured with clinical tools that include technological resources. The clinical value of identifying individuals with prodromal DV is highlighted as it could optimize prevention measures.(AU)

[Vascular damage and cognitive-functional performance in a population with mild cognitive impairment]. / Daño vascular y rendimiento cognitivo-funcional en una población con deterioro cognitivo leve.

INTRODUCTION: There is evidence of predemential stages in Vascular Dementia (VD). Alzheimer Disease (AD) and VD share common risk factors and mechanisms. Vascular comorbility may present in 30-60% of patients with AD (mixed dementia). This work seeks to evaluate the impact of the severity of structural vascular damage according to the Fazekas classification (F) on functional cognitive performance in patients with Mild Cognitive Impairment (MCI). PATIENTS AND METHODS: A cross-sectional study of patients with MCI aged 65 years or older who had brain MRI was carried out. A neurocognitive battery and the EFE (Extended Functional Study) scale were administered to assess complex functionality. The patients were divided according to Fazekas classification: 0-1, 2 and 3. Bivariate analysis and multivariate analysis were performed. RESULTS: 346 patients were included, age: 77.9 (SD 6.1). 66.2% presented F01, 22.8% F2 and 11% F3. Age and MMSE value were statistically significant. Multivariate analysis showed an independent association between vascular damage and complex functional alteration measured by EFE. CONCLUSIONS: In conclusion, the progression of structural damage to a predominance of white matter would affect global cognitive performance and tasks related to executive function. The most significant finding was the correlation of the degree of vascular damage with the deficit of complex functionality measured with clinical tools that include technological resources. The clinical value of identifying individuals with prodromal DV is highlighted as it could optimize prevention measures.

TITLE: Daño vascular y rendimiento cognitivo-funcional en una población con deterioro cognitivo leve.Introducción. Existe evidencia de etapas predemenciales en la demencia vascular. La enfermedad de Alzheimer y el trastorno cognitivo vascular comparten mecanismos de riesgo comunes, y la comorbilidad vascular puede estar presente en el 30-60% de los pacientes con enfermedad de Alzheimer. Este trabajo evalúa el impacto de la gravedad del daño vascular estructural según la clasificación de Fazekas en el desempeño cognitivo funcional en pacientes con deterioro cognitivo leve (DCL). Pacientes y métodos. Estudio de corte transversal de pacientes con DCL de 65 años o más con resonancia magnética cerebral. Se administró una batería neurocognitiva y la escala estudio funcional extendido (EFE) para evaluar la funcionalidad compleja. Los pacientes se clasificaron según Fazekas: 0-1, 2 y 3. Se realizó un análisis bivariado y un análisis multivariable. Resultados. Se incluyó a 346 pacientes, con una edad de 77,9 (desviación estándar: 6,1). El 66,2% presentó Fazekas 0-1; el 22,8%, Fazekas 2; y el 11%, Fazekas 3. La edad y el valor del Minimental State Examination se asociaron con un Fazekas más avanzado. El análisis multivariado mostró una asociación independiente entre el daño vascular y la alteración funcional compleja medida por el EFE. Conclusiones. La progresión del daño estructural a predominio de sustancia blanca afectaría al desempeño cognitivo global y a las tareas de función ejecutiva. El hallazgo más significativo fue la correlación del grado del daño vascular con el déficit de la funcionalidad compleja medida con herramientas clínicas que incluyeron recursos tecnológicos. Se resalta el valor clínico de identificar los individuos con demencia vascular prodrómica, ya que podría optimizar las medidas de prevención.

A genome-wide association study identifies novel gene associations with facial skin wrinkling and mole count in Latin Americans.

BACKGROUND: Genome-wide association studies (GWASs) have identified genes influencing skin ageing and mole count in Europeans, but little is known about the relevance of these (or other genes) in non-Europeans. OBJECTIVES: To conduct a GWAS for facial skin ageing and mole count in adults < 40 years old, of mixed European, Native American and African ancestry, recruited in Latin America. METHODS: Skin ageing and mole count scores were obtained from facial photographs of over 6000 individuals. After quality control checks, three wrinkling traits and mole count were retained for genetic analyses. DNA samples were genotyped with Illumina's HumanOmniExpress chip. Association testing was performed on around 8 703 729 single-nucleotide polymorphisms (SNPs) across the autosomal genome. RESULTS: Genome-wide significant association was observed at four genome regions: two were associated with wrinkling (in 1p13·3 and 21q21·2), one with mole count (in 1q32·3) and one with both wrinkling and mole count (in 5p13·2). Associated SNPs in 5p13·2 and in 1p13·3 are intronic within SLC45A2 and VAV3, respectively, while SNPs in 1q32·3 are near the SLC30A1 gene, and those in 21q21·2 occur in a gene desert. Analyses of SNPs in IRF4 and MC1R are consistent with a role of these genes in skin ageing. CONCLUSIONS: We replicate the association of wrinkling with variants in SLC45A2, IRF4 and MC1R reported in Europeans. We identify VAV3 and SLC30A1 as two novel candidate genes impacting on wrinkling and mole count, respectively. We provide the first evidence that SLC45A2 influences mole count, in addition to variants in this gene affecting melanoma risk in Europeans.

Intervenciones terapéuticas en psicosis esquizofrénica de niños y adolescentes / Therapeutic interventions in schizophrenic psychosis in children and adolescents

La prevalencia de Esquizofrenia es muy baja en la infancia y adolescencia temprana, aumentando en la adolescencia y adultez a un 1%. Se ha estimado que la prevalencia de psicosis de 0,9 en 10.000 a los 13 años y 17,6 en 10.000 a los 18 años. Los cuadros esquizofrénicos de inicio temprano y muy temprano son una variante severa del trastorno y se asocian a un mayor deterioro funcional, curso clínico más grave y peor evolución. Todo esto determina la necesidad de implementar tratamientos multimodales tempranos y eficaces, así como estrategias preventivas en los grupos de mayor riesgo. El tratamiento farmacológico cuenta con mayores evidencias de efectividad en este cuadro y otorga notables beneficios a los pacientes, sin embargo se requiere mayor investigación a largo plazo respecto a los efectos adversos secundarios, su impacto en individuos en desarrollo y la eficacia de estos agentes. Estos avances permitirán al clínico establecer un justo balance costo/beneficio de su uso en población infantojuvenil.

The prevalence of schizophrenia is very low during childhood and early adolescence, increasing later in adolescence and adulthood to 1%. It has been established that the prevalence of psychosis is 0.9/10000 at 13 years of age and 17.6/10000 at 18 years of age. Early and very early onset schizophrenia are a severe form of this disorder, and are associated to a larger disability, more severe form of the disease and worse prognosis. These factors determine the need of implementing treatments that are multimodal, early and effective, as well as preventive strategies in high risk groups. The pharmacological treatment of schizophrenia has evidence of effectiveness and gives patients important benefits, however, more long term research is needed regarding its side effects, its impact on the developing brain and its effectiveness. These facts would help the psychiatrist to establish the value, risks and benefits of the use of drugs in children and adolescents.

Psicofármacos en niños y adolescentes II: psicoestimulantes, estabilizadores del ánimo y benzodiacepinas. revisión / Psychopharmacology in children and adolescents II: psychostimulants, mood stabilizers and benzodiazepines. review

Psicoestimulantes (PSE), estabilizadores del ánimo (EA) y benzodiacepinas (BDZ) son psicofármacos frecuentemente utilizados en psiquiatría infantojuvenil y cuya indicación ha aumentado considerablemente en los últimos años. Los PSE son empleados principalmente en el déficit atencional, siendo la terapia de primera línea en pacientes sin comorbilidad. Modafinilo y anfetaminas serían igualmente efectivos y se utilizan con similar frecuencia en muchos países sin embargo existe evidencia de mayores riesgos con anfetaminas. Otros fármacos como atomoxetina, a-agonistas, bupropión y antidepresivos tricíclicos (imipramina) se utilizan como tratamiento de segunda o tercera línea. Los EA son especialmente útiles en el tratamiento del trastorno bipolar (TB) y se consideran agentes de primera línea: litio, ácido valproico (sodio divalproex) y algunos antipsicóticos atípicos. Otros EA que han demostrado efectividad en TB son lamotrigina, carbamazepina, oxcarbamazepina y topiramato. Las DBZ han sido poco estudiadas en población infantojuvenil, pero su uso no es infrecuente. Si bien no son una indicación de primera línea en trastornos de ansiedad, están indicadas como tratamiento adyuvante especialmente diazepam. Fluracepam tiene un rol en el tratamiento de insomnio en mayores de 15 años. Aunque el tratamiento de elección de muchas patologías de psiquiatría infantojuvenil es claro en diversas guías clínicas, la complejidad terapéuticas de estos pacientes muchas veces hace necesario el uso de psicofármacos de segunda o tercera línea, muchos de ellos no aprobados por la Food and Drug Administration. Es estos casos cobra vital importancia el seguimiento estricto, con especial cuidado en los efectos colaterales, que pueden ser nocivos para el desarrollo del paciente.

Psycho stimulants (PSE), mood stabilizers (ME) and benzodiazepines (BDZ) are psychotropic’s frequently used in children and adolescents psychiatry and their indication has increased considerably in the last year. The PSAE are used mainly in attentional deficits being first-line treatment in patients without co-morbidity. Modafinil and amphetamines are supposed to be equally effective and used with similar frequency in many countries, however there is evidence of bigger risk with amphetamines. Other drugs such as Atomoxetine, a-agonist, bupropion, tricyclic antidepressants (imipramine) are used as second or third line treatment. The ME are especially useful as treatment of bipolar disorder (BD); lithium, divalproex sodium and some atypical antipsychotics are considered first line treatment. Other ME that have showed effectiveness in TB are lamotrigine, carbamazepine, oxcarbamazepina and topiramate. The BDZ haven´t been studied too much in young population, however its uses not uncommon. Although it is not a first line indication in anxiety disorders they are indicated as adjunctive treatment, especially diazepam. Fluracepam has a role in the treatment of insomnia in children over 15 years. While the treatment of choice for many pathologies of juvenile psychiatry is clear in several clinical guidelines, the therapeutic complexity of these patients often requires the use of psychopharmacology of 2nd or 3rd line, many of them not approved by the Food and Drug Administration in these cases is of vital importance a strict monitoring, with particular attention to side effects, which can be harmful to the patients development.

Psicofármacos en niños y adolescentes I: antidepresivos y antipsicóticos / Psychopharmacology in children and adolescents I: antipsychotic and antidepressant

Los inhibidores selectivos de la recaptación de serotonina (ISRS) en la actualidad son ampliamente utilizados en niños y adolescentes con diversas patologías psiquiátricas, especialmente en Trastornos (T) del ánimo y T. ansiosos. Son el tratamiento farmacológico de primera línea en depresión, T. de pánico, T. de ansiedad generalizada, T. de ansiedad de separación y T. obsesivo compulsivo, existiendo escasas diferencias documentadas entre los distintos subtipos de ISRS. Los antidepresivos tricíclicos, pese a su demostrada eficacia, son fármacos de uso muy restringido en este grupo etario debido a sus efectos adversos y elevado riesgo en caso de sobredosis. Los antipsicóticos (AP) también son ampliamente utilizados, siendo los AP atípicos el tratamiento de elección en múltiples patologías como esquizofrenia, T. bipolar, T. de la Tourette y por tics, T. generalizado del desarrollo asociado a comportamiento disruptivo, déficit atencional con T. conductuales severos (para manejar la impulsividad y agresividad) y en comportamientos aberrantes en pacientes con retardo mental o autismo. El principal inconveniente de los AP son sus efectos colaterales, siendo mayores con los AP típicos, por lo que se reservan como tratamiento de segunda línea en caso de fracaso de los AP atípicos.

Selective inhibitors (SSRIS) serotonin reuptake are today widely used in children and adolescents in several psychiatric diseases, especially anxious disorders and mood disorders. They are the first line pharmacological treatment for depression, panic disorder, generalized anxiety disorder, separation anxiety disorder and obsessive compulsive disorder, and there are few documented differences between the different subtypes of SSRIs. Tricyclic antidepressants instead, despite its demonstrated efficacy are severely restricted drugs in this age group due to its potential adverse effects and elevated risk in case of overdose, reserving its use for very defined cases. Antipsychotics (APS) on the other side are also widely used in children and adolescents, being the atypical AP treatment of choice in multiple pathologies such as schizophrenia, bipolar disorder, Tourette’s disorder and tics, generalized developmental disorder associated with disruptive behavior, attentional deficit with severe behavioral disorders, impulsivity and aggression management and aberrant behavior in patients with mental retardation or autism. However its main problem are side effects, even more with typical AP so that are generally reserved as a second line treatment in the event of failure of atypical AP.

Reacciones cutáneas adversas a anticonvulsivantes y estabilizadores del ánimo / Adverse cutaneous reactions to anticonvulsants and mood stabilizers

Anticonvulsivantes y estabilizadores del ánimo principalmente el ácido valproico, lamotrigina y carbamazepina, poseen una alta incidencia de reacciones adversas a medicamentos (RAM) severas, como eritema multiforme, Síndrome Stevens- Johnson y necrolisis epidérmica tóxica, asociadas. Existen signos de alarma para su sospecha diagnóstica precoz, que permiten indicar la temprana suspensión del fármaco sospechoso e iniciar la terapia de soporte únicas medidas que han demostrado una clara disminución en la mortalidad. La inmunoglobulina G intravenosa se recomienda por su seguridad, sin embargo, su rol en disminuir la mortalidad es contradictorio. Los corticoides no han demostrado cambios en la mortalidad comparados con la terapia de soporte exclusiva. Se ha intentado mantener el tratamiento con lamotrigina, por sus cualidades terapéuticas, pese a la aparición de RAM cutáneas. De hecho, en estudios recientes en pacientes que han desarrollado RAM leves a este producto se ha demostrado un éxito de reexposición de 85 por ciento-87 por ciento mediante una lenta titulación de la dosis.

Anticonvulsants and mood stabilizers mainly valproic acid, lamotrigine and carbamazepine are medications that have a high incidence of severe adverse drug reactions (ADRs), such erythema multiforme, Stevens- Johnson syndrome and toxic epidermal necrolysis. Early diagnosis based in systemic and cutaneous alarm signs have been described, allowing premature discontinuation of suspected drugs and start supportive therapy; these are the only measures that have that have shown clear reduction in mortality. The use of intravenous immunoglobulin G is recommended for their safety, but studies regarding their role in reducing mortality are conflicting. Corticosteroids have not proved changes in mortality compared with exclusive supportive care. Due to therapeutic quality Lamotrigine is used despite the incidence of ADRs. In fact in recent studies patients with mild ADRs to this drug have shown between 85 percent-87 percent of success, when patients are re-exposed through a slow increasing in dosage.

Isolation of viable porcine islets by selective osmotic shock without enzymatic digestion.

Islet transplantation is a potential cure for type 1 diabetes, but clinical results have been disappointing. Currently, islet isolation is by enzymatic digestion of the pancreas which has significant pitfalls: warm ischemia exposure, collagenase-induced damage to the islet mass and viability, poor reproducibility, high cost, a relatively low number of islets obtained per whole pancreas, and selection of islets for collagenase resistance rather than for glucose responsiveness. In the present study we performed a series of experiments in a porcine model to demonstrate the feasibility of a new isolation method based on selective osmotic shock (SOS) using very high glucose solutions, doubling or tripling physiological osmotic strength. The SOS method can be carried out at room temperature or in the cold eliminating warm ischemia time which damages the islets. The SOS method does not depend on the texture of the pancreas so all pancreases can be processed identically and the process can be fully automated. The SOS method isolates all the islets of the pancreas regardless of size and shape allowing a greater number of islets to be harvested. The SOS method avoids exposure to toxins in collagenase solutions, is inexpensive and selects for islets with high concentrations of Glut 2 transporters, representing the best glucose responding islets. The SOS method showed a comparable recovery of islets from young pig pancreas and the islets showed improved viability. We conclude that the selective osmotic shock (SOS) method of separating islets from the pancreatic tissue is superior to the collagenase method.

The in vitro protective effect of alpha-tocopherol on oxidative injury in the dog retina.

Oxidative stress is a risk factor for eye diseases. Free radicals elicited during the inflammatory process often lead to oxidative damage of lipids (lipid peroxidation). The retina is highly vulnerable because of its high content of polyunsaturated fatty acids (PUFAs). The aim of this study was to investigate in vitro the effect of alpha-tocopherol on the Fe(2+)-ascorbate induced lipid peroxidation in the canine retina. Lipid peroxidation of retinal homogenates was carried out with and without the addition of alpha-tocopherol and monitored both by chemiluminescence and production of thiobarbituric acid reactive substances (TBARS). Total chemiluminescence counts per minute was lower in those homogenates pre-incubated with alpha-tocopherol. Thus, with 1 micromol alpha-tocopherol/mg of protein, 100% inhibition of chemiluminescence and a decrease of TBARS content from 20.46+/-0.85 to 2.62+/-2.77 nmol/mg protein were observed. Simultaneously, changes produced by oxidative stress were noted in the fatty acid composition of retinal lipids. Docosahexaenoic acid was decreased from 14.33+/-2.32% to 1.84+/-0.14% after peroxidation, but this fatty acid remained unaltered in the presence of 1 micromol alpha-tocopherol. These results show that under these experimental conditions, alpha-tocopherol may act as anti-oxidant protecting retinal membranes from deleterious effects. Further studies are required to assess its use in free radical generating conditions affecting the canine retina.

Selective inhibition of the non-enzymatic lipid peroxidation of phosphatidylserine in rod outer segments by alpha-tocopherol.

In the present study it was investigated if alpha-tocopherol shows protection against in vitro lipid peroxidation of phospholipids located in rod outer segment membranes (ROS). After incubation of ROS in an ascorbate-Fe2+ system, at 37 degrees C during 160 min, the total cpm originated from light emission (chemiluminescence) was found to be lower in those membranes incubated in the presence of alpha-tocopherol. The fatty acid composition of total lipids isolated from rod outer segment membranes was substantially modified when subjected to non-enzymatic lipid peroxidation with a considerable decrease of docosahexaenoic acid (22:6 n-3). The incorporation of alpha-tocopherol (0.35 micromol/mg protein) produce a 43.37% inhibition of the lipid peroxidation process evaluated as chemiluminescence (total cpm originated in 160 min). The phospholipid species containing the highest amount of docosahexaenoic acid: phosphatidylethanolamine and phosphatidylserine were more affected than phosphatidylcholine during the lipid peroxidation process. Not all phospholipids, however, were equally protected after the addition of alpha-tocopherol to the incubation medium. Phosphatidylcholine and phosphatidylethanolamine, were not protected by alpha-tocopherol, the vitamin provides selective antioxidant protection only for phosphatidylserine. These results indicate that alpha-tocopherol may act as antioxidant protecting rod outer segment membranes from deleterious effect by a selective mechanism that diminishes the loss of docosahexaenoic acid from phosphatidylserine.

The effect of alpha tocopherol, all-trans retinol and retinyl palmitate on the non enzymatic lipid peroxidation of rod outer segments.

The effect of a tocopherol, all-trans retinol and retinyl palmitate on the non enzymatic lipid peroxidation induced by ascorbate-Fe2+ of rod outer segment membranes isolated from bovine retina was examined. The inhibition of light emission (maximal induced chemiluminescence) by alpha tocopherol, all-trans retinol and retinyl palmitate was concentration dependent. All trans retinol showed a substantial degree of inhibition against ascorbate-Fe2+ induced lipid peroxidation in rod outer segment membranes that was 10 times higher than the observed in the presence of either at tocopherol or retinyl palmitate. Inhibition of lipid peroxidation of rod outer segment membranes by alpha tocopherol and retinyl palmitate was almost linear for up to 0,5 micromol vitamin/mg membrane protein, whereas all-trans retinol showed linearity up to 0,1 micromol vitamin/mg membrane protein. Incubation of rod outer segments with increasing amounts of low molecular weight cytosolic proteins carrying I-[14C] linoleic acid, [3H] retinyl palmitate or [3H] all-trans retinol during the lipid peroxidation process produced a net transfer of ligand from soluble protein to membranes. Linoleic acid was 4 times more effectively transferred to rod outer segment membranes than all-trans retinol or retinyl palmitate. Incubation of rod outer segments with delipidated low molecular weight cytosolic proteins produced inhibition of lipid peroxidation. The inhibitory effect was increased when the soluble retinal protein fraction containing alpha tocopherol was used. These data provide strong support for the role of all-trans retinol as the major retinal antioxidant and open the way for many fruitful studies on the interaction and precise roles of low molecular weight cytosolic retinal proteins involved in the binding of antioxidant hydrophobic compounds with rod outer segments.

Lipoperoxidation of rod outer segments of bovine retina is inhibited by soluble binding proteins for fatty acids.

In the present study it was investigated if soluble-binding proteins for fatty acids (FABPs) present in neural retina show protection from in vitro lipoperoxidation of rod outer segment membranes (ROS). After incubation of ROS in an ascorbate-Fe++ system, at 37 degrees C during 90-120 min, the total cpm originated from light emission (chemiluminescence) was found to be lower in those membranes incubated in the presence of soluble binding proteins for fatty acids. The fatty acid composition of rod outer segment membranes was substantially modified when subjected to non-enzymatic lipoperoxidation with a considerable decrease of docosahexaenoic acid (22:6 n-3) and arachidonic acid (20:4 n-6). As a result of this, the unsaturation index, a parameter based on the maximal rate of oxidation of specific fatty acids was higher in the native and control membranes when compared with peroxidized ones. A similar decrease of chemiluminescence was observed with the addition of increasing concentrations of native or delipidated FABP retinal containing fractions to rod outer segment membranes. These results indicate that soluble proteins with fatty acid binding properties may act as antioxidant protecting rod outer segment membranes from deleterious effect.

Zinc heparin introduces a preanalytical error in the measurement of ionized calcium concentration.

In this study we determined how zinc heparin affected ionized calcium concentration determinations. Zinc heparin produced a positive bias (0.020-0.067 mmol l-1) in ionized calcium measurement in serum/whole blood and a negative bias (-0.035 to -0.110 mmol l-1) with aqueous ionized calcium standards. To test if the positive bias was due to zinc ions displacing calcium from its protein-calcium complexes, we reproduced the effect by adding ZnCl2 to pooled serum. Changes in [ZnCl2] (0.1-0.5 mmol l-1) caused a dose-dependent increase, a constant bias ([ZnCl2], 0.5-1.25 mmol l-1) or a dose-dependent decrease ([ZnCl2] > 1.25 mmol l-1) in ionized calcium concentration, independent of pH. Similar results were obtained when zinc concentration of the specimen was changed by varying the volume of blood collected into syringes containing zinc heparin. We conclude that zinc heparin produces a positive bias in ionized calcium measurement in protein-based matrices.

[Aneurysm of the Galeno's vein: report of a case]. / Aneurisma de la vena de Galeno: informe de un caso.

Some aspects of pathophysiology, diagnosis and treatment of gastroesophageal reflux (GER) in children are presented. There is considered a multifactorial syndrome. The objective of this review is present new trends in etiology, diagnostic methods, in a practical point of view, specially in places without sophisticated equipment. Finally it is presented rational therapeutical basis en GER management.

Glial polyp of the cervix and endometrium. Report of a case and review of the literature.

This paper describes the case of an 18-year-old woman who had recurrent inflammatory cervical endometrial polyps due to glial implantation after a spontaneous abortion treated with curettage. The lesion is considered benign.