Anatomía Comparada del Bazo de la Rata Blanca (Rattus norvegicus albinus), Una Revisión de la Literatura / Comparative Anatomy of the Spleen of the White Rat, (Rattus norvegicus albinus) a Literature Review

El bazo es el órgano linfático intraperitoneal más grande del organismo, presentando dos funciones principales: defensiva, mediante respuesta inmunitaria y filtración sanguínea. El objetivo de la presente revisión, fue obtener información actualizada sobre la anatomía del bazo de la rata albina (Rattus norvegicus albinus) y comparativa con la anatomía del bazo humano, perro, gato y cerdo, al representar las principales especies de importancia en la medicina, medicina veterinaria y en las ciencias biomédicas. Se realizó una búsqueda de material bibliográfico actualizado en diferentes sitios web científicos. Es así como, se revisaron 71 fuentes bibliográficas, en su gran mayoría artículos científicos (31), libros de anatomía humana y veterinaria (17), artículos especializados (17) y tesis (6). En general existe consenso, sobre la descripción anatómica del bazo, el cual se sitúa en la región hipocondriaca izquierda del abdomen, entre el fondo del estómago y el diafragma, irrigado por la arteria y vena esplénica. Se evidenció que existen similitudes en aspectos macroscópicos, al comparar el bazo de la rata blanca, con el bazo de otras especies (funcionalidad, peso relativo, ubicación topográfica). En aspectos microscópicos, el bazo en humanos y otros mamíferos se compone de estroma, además de parénquima, constituido a su vez por pulpa blanca y roja. En particular, existen diferencias entre el bazo de rata, humano, gato, perro y cerdo, en formas, tamaños y aspectos microscópicos, relacionados con la microcirculación e inmunidad. Mientras que existen semejanzas en procesos patológicos y respuestas a tratamientos farmacológicos y clínicos. Por lo anteriormente expuesto, se concluye que la rata albina constituye un buen modelo biológico, específicamente en aspectos anatómicos microscópicos del bazo de tipo inmunológico. Mientras que el bazo de cerdo es mejor comparativamente, en estudios anatómicos macroscópicos de tipo quirúrgicos, resultando ambos extrapolables, especialmente a la medicina humana.

SUMMARY: The spleen is the largest intraperitoneal lymphatic organ of the body, presenting two main functions: defensive, through immune response and blood filtration. The objective of the present review was to obtain updated information on the anatomy of the spleen of the albino rat (Rattus norvegicus albinus) and to compare it with the anatomy of the human, dog, cat and pig spleen, representing the main species of importance in medicine, veterinary medicine and biomedical sciences. A search for updated bibliographic material was carried out in different scientific websites. Thus, 71 bibliographic sources were reviewed, mostly scientific articles (31), human and veterinary anatomy books (17), specialized articles (17) and theses (6). In general, there is consensus on the anatomical description of the spleen, which is located in the left hypochondriac region of the abdomen between the fundus of the stomach and the diaphragm, irrigated by the splenic artery and vein. It was evidenced that there are similarities in macroscopic aspects when comparing the spleen of the white rat with the spleen of other species (functionality, relative weight, topographic location). In microscopic aspects, the spleen in humans and other mammals is composed of stroma, in addition to parenchyma, constituted in turn by white and red pulp. In particular, there are differences between rat, human, cat, dog and pig spleens in shapes, sizes and microscopic aspects related to microcirculation and immunity. While there are similarities in pathological processes and responses to pharmacological and clinical treatments. For the above mentioned, it is concluded that the albino rat constitutes a good biological model, specifically in microscopic anatomical aspects of the spleen of immunological type. While the pig spleen is comparatively better in macroscopic anatomical studies of surgical type, both are extrapolable especially to human medicine.

Composição química da forragem e do ensilado de azevém anual em função de diferentes tempos de secagem e estádios fenológicos / Chemical composition of annual ryegrass forage and silage for different drying times and phenological phases

O objetivo do presente estudo foi determinar como o tempo de secagem e o estádio fenológico da planta influenciam na composição química e qualidade da silagem de azevém (Lolium multiflorum, Lam.). O delineamento experimental foi de blocos ao acaso, com seis tratamentos (vegetativo: cortar e ensilar; cortar + pré-secagem de 4 horas e ensilar; cortar + pré-secagem de 7 horas e ensilar; pré-florescimento: ensilagem, cortar e ensilar e pré-secagem de 4 horas; florescimento: cortar e ensilar) e quatro repetições, com quatro meses de conservação da silagem. Foram determinados: desaparecimento de massa após o corte, rendimento de massa seca, proteína bruta e frações fibrosas. Além disso, foram determinados na silagem: pH, lipídios totais, nitrogênio insolúvel em detergente neutro e ácido. O manejo empregado auxilia na desidratação da forragem, com perda na quantidade de nitrogênio no vegetativo. No pré-florescimento, essa perda não ocorre. O avanço do ciclo da forrageira ocasiona diminuição na quantidade de nutrientes na biomassa, entretanto a produção de forragem é aumentada. A silagem apresentou composição bromatológica semelhante à observada na massa verde de azevém, o que demonstra a eficiência do método de conservação. A ensilagem em estádios mais avançados é aconselhada quando se busca maior quantidade de biomassa ensilada, porém com qualidade inferior.(AU)

The aim was how to define the effect of pre-drying time and the plant phase's influence on chemical composition and quality of ryegrass silage. The experimental design was randomized blocks with six treatments (Vegetative: Cut and ensiled; cut + pre-drying 4 hours and ensiled and; cut + pre-drying of 7 hours and ensiled; Pre-flowering: Silage cutting and ensiled and pre-drying 4 hours Flowering:. cut and ensiled) and four repetitions. The silage was stowed for four months. It were determined the mass disappearance after cutting, dry matter yield, crude protein and fiber fractions. Moreover, it was determined on silage pH, total lipids and insoluble protein content. The management used aids in dehydration of fodder, resulting in losses on the amount of nitrogen on vegetative phase. For pre-flowering, this loss has not occur. The advance of fodder cycle causes a decrease in the amount of nutrients in biomass, but fodder yield increased. Ryegrass silage presented chemical composition similar to that observed on green mass of ryegrass, evinced the efficiency of fodder conservation method. The silage in more advanced phases is advised when seeking greater amount of ensiled biomass, but lower quality.(AU)

La neuroinflamación como factor detonante del desarrollo de la enfermedad de alzheimer: [revisión] / Neuroinflammation as a triggering factor for alzheimer's disease: [review]

The progressive increase in life expectancy of the world population has fostered a major concern in order to find effective avenues for diagnosis of treatment of Alzheimer's disease (AD). Even tough AD pathogenesis is still unclear, new advances have allowed to understand that exposure of individuals to a series of environmental risk factors, named to as damage signals, play a main role in triggering the disease. This is important for AD prevention but also for the search of new treatment approaches. Activation of innate immunity in the central nervous system (CNS), essentially microglial cells, appears to be a key element in the neurodegenerative pathway As a matter of fact, when microglia cells are exposed continuously to damage signals such as metabolites from conditions of hyperlipidemia, hyperglycemia, oxidative stress, head injury and trauma, recurrent infections, in addition to supramolecular aggregates such as tau filaments or b-amyloid oligomers, among other anomalous protein filaments, they respond by triggering the inflammatory cascade. On this basis, we have postulated the neuroimmunomodulation hypothesis for Alzheimer's Disease. Therefore, we postulates that a long-term activation of brain innate immunity by a converging set of damage signals constitute a unifying mechanism that triggers the inflammatory cascade, thus leading to irreversible alteration in the neuronal cytoskeleton. These concerted alterations in signaling mechanisms will lead in neuronal cells to a final common pathway, tau hyperphosphorylations, with the consequent self-aggregation of modified tau and formation of paired helical filaments (PHFs), as the main triggering event for neurodegenration in AD.

El constante aumento en la expectativa de vida en la población mundial ha incrementado la preocupación hacia la búsqueda de la comprensión de la Enfermedad de Alzheimer (EA), así como de su diagnóstico temprano y tratamiento. Actualmente la etiopatogenia que conduce al desarrollo de la EA es aún difusa, pero se ha llegado a comprender que la exposición a una serie de distintos factores de riesgo, o señales de daño, está asociada al desencadenamiento de la EA. Esto es muy importante no solo para la prevención de esta devastadora enfermedad sino también para la búsqueda de avenidas efectivas para su tratamiento. En efecto, la activación de la inmunidad innata en el sistema nervioso central (SNC), esencialmente por las células microgliales, son un elemento clave en el proceso neurodegenerativo, cuando éstas son expuestas por períodos prolongados a señales de daño. Entre éstas están la hiperlipidemia, hiperglicemia, estrés oxidativo, traumatismos, infecciones recurrentes, oligomeros de -amiloide, agregados de tau, entre otros factores, los que desencadenarían una respuesta pro-inflamatoria persistente que conduce a la cascada neurodegenerativa. En base a esto, hemos postulado la teoría de la neuroinmunomodulación en la EA, y proponemos que la activación a largo plazo del sistema inmune innato por un conjunto de señales de daño constituye un mecanismo unificado que gatillo, una cascada inflamatoria que conduce a alteraciones irreversibles en el citoesqueleto. Estos mecanismos anómalos de señalización molecular llevarían a una vía final común que es la hiperfosforilación de la proteína tau, su autoagregación y formación de los PHFs, como desencadenantes claves en la neurodegeneración y desarrollo de la EA.

Uso de plasmaféresis en unidades de pacientes críticos / Indications, adverse effects and results of plasmapheresis in critical care patients

Background: Plasmapheresis is a therapeutic alternative for diseases in which a "humoral factor" has pathogenetic relevance. However it is not devoid of adverse effects. Aim: To review the indications, number of procedures, morbidity and clinical evolution of plasmapheresis in critical patients. Patients and Methods: A retrospective and descriptive study in four intensive care units of an University hospital. The severity of patients was evaluated with APACHE II and SOFA scores. Results: Twenty patients were studied. The most common indications of plasmapheresis were thrombotic thrombocytopenic purpura (TTP) in 50% of subjects and small vessel vasculitides in 30%. The number of procedures per patient oscillated between 2 and 14 (mean: 7.1±3.3). The registered adverse effects were hypocalcemia in 50% of patients, hypotension in 42.1%, coagulopathy in 35%, hypokalemia in 29%, rash in 20%, procedure related infections in 18% and fever in 10%. There was a significant decrease of 17±28% in prothrombin time, after the procedures. Seventy five percent of patients had a favorable evolution. Global mortality rate was 15%. All deaths occurred in patients with TTP and were attributed to the progression of the disease. No death was attributed to the procedure. The initial APACHE II and SOFA scores were 12.4±8.4 and 5.3±2.9, respectively. Both scores decreased after the procedure. Among other therapeutic measures, 15% of the patients received immunosuppressant treatment, 27% were dialyzed and 32% were mechanically ventilated. Conclusions: The most common indication of plasmapheresis was TTP. Adverse effects were frequent, however there was no procedure related mortality. The global mortality rate was 15% and all deaths occurred in patients with TTP.

Determinación y análisis comparativo de gasto cardíaco en enfermos críticos mediante Doppler transesofágico y termodilución en bolos: Experiencia preliminar / Comparison of cardiac output measurement in critical patients using transesophageal Doppler or thermodilution: A preliminary report

Background: Cardiac output can be measured non invasively by transesophageal Doppler. This is an alternative to measure it by thermodilution with a catheter in the pulmonary artery. Aim: To compare both methods of cardiac output measurement. Material and methods: Simultaneous measurement of cardiac output by transesophageal Doppler and thermodilution with a catheter in the pulmonary artery in four male critical patients, aged 60±12 years, hospitalized in a University Hospital. The Bland and Altman method to compare the concordance between two measurements, was used. Results: Forty measurements were performed. The results of both methods had a correlation coefficient of 0.98. According to the Bland and Altman method, the difference between both methods was -0.5 L with a precision of 0.52 L/min (95% confidence interval -1.51 to 0.52 L/min). Considering that a change between two sequential measurements is considered significant when the difference is more than 15%, both measurements agreed in 83% of cases, that there was a change in cardiac output. Conclusions:Transesophageal Doppler is a promising non invasive technique to measure cardiac output in critical care patients. It becomes a valid alternative to the thermodilution technique. This preliminary experience must be confirmed in a larger series.

Diseño de un índice pronóstico clinico para el manejo de la neumonía del adulto adquirida en la comunidad / Development of an instrument to assess the severity of community acquired pneumonia among hospitalized patients

BACKGROUND: Community acquired pneumonia (CAP) severity assessment is crucial. AIM: To develop a practical clinical severity assessment model for stratifying immunocompetent adult patients hospitalized with CAP into different management groups. PATIENTS AND METHODS: During a 24 months period, 455 adult patients (250 male, mean age 69 +/- 19 years old) were evaluated. All the relevant clinical information recorded and they were followed during hospital stay until discharge or death. Mortality until 30 days after admission was determined. RESULTS: The mean hospital length of stay was 9.9 +/- 9.4 days and 76% had an underlying disease. In hospital mortality was 7.6% and 10.1% at 30 days follow up. Admission prognostic factors associated with high mortality at 30 days follow up were: advanced age, presence of comorbidity, suspicion of aspiration, duration of symptoms < or = 2 days, altered mental status, absence of cough, fever and cbills, low blood pressure, tachypnea, hypoxemia and multilobar radiographic pulmonary infiltrates. A clinical prognostic index derived from a logistic regression analysis including five independent variables associated with mortality (confuson, comorbidity, low systolic blood pressure, temperature < 37.5 degrees C and respiratory rate > 20/min), enabled patients to be stratified according to increasing risk of mortality: class 1: 0.9%, class 2: 4.9%, class 3: 14.2%, and class 4: 35.6%. CONCLUSION: A simple clinical severity assessment tool based on confusion, comorbidity, blood pressure, temperature and respiratory rate could be used to stratify patients with CAP into different risk class categories and management groups.

Neumonía adquirida en la comunidad en el adulto hospitalizado. Cuadro clínico y factores pronósticos / Community-acquired pneumonia in hospitalized adult patients. Clinical presentation and prognostic factors

BACKGROUND: Community-acquired pneumonia (CAP) is a serious health problem in Chile. AIM: To study prognostic factors on admission and outcome of CAP, in immune competent adult patients, hospitalized in the Catholic University Clinical Hospital. PATIENTS AND METHODS: All adult patients admitted with a CAP in a period of 2 years were prospectively studied. Patients with immunodeficiency, solid tumors or receiving oral adrenal steroids were excluded from the study. RESULTS: In the study period, 463 patients (69 +/- 19 years, 55 per cent male) were evaluated. Ninety four percent were treated with 2nd or 3rd generation cephalosporins. Mean hospital length of stay was 10 days. Mortality during hospital stay was 8 per cent and in the ensuing 30 days, it was 12 per cent. Bacterial etiology was established in 25 per cent of cases. The most frequent pathogens isolated were Streptococcus pneumoniae (10.2 per cent), Haemophilus influenzae (3.7 per cent), Staphylococcus aureus (2.8 per cent) and Gram negative bacilli (5.2 per cent). Admission prognostic factors associated with hospital mortality were an age over 65 years, presence of comorbidity, chronic neurological and hepatic disease, suspicion of aspiration, duration of symptoms for less than 3 days, presence of dyspnea and altered mental status, absence of cough, fever and chills; low blood pressure, tachypnea, metabolic acidosis, hypoxemia, high blood urea nitrogen, hypernatremia, hyperkalemia, hyperphosphatemia, hypoalbuminemia, multilobar radiographic pulmonary infiltrates, bacteremia, high risk categories of the Fine Index (IV and V), and admission to Intermediate Care Unit or ICU. CONCLUSIONS: The features of community acquired pneumonia of these patients are similar to those reported abroad.

Utilidad clínica de los hemocultivos en pacientes hospitalizados por neumonía adquirida en la comunidad / Clinical usefulness of blood cultures in hospitalized patients with community acquired pneumonia

Background: The clinical role of blood cultures (BC) in the management of hospitalized patients with community-acquired pneumonia (CAP) is controversial. Aim: To evaluate the clinical usefulness of blood cultures in CAP. Material and methods: We prospectively studied 244 immunocompetent adults with two or more BC obtained at admission. The diagnostic yield of BC and its impact on antibiotic therapy were assessed. Results: Mean age (xñsd) of patients was 67ñ20 years, 80 percent had underlying diseases and 29 percent received antibiotics prior to admission. Hospital length of stay was 10.4ñ10 days and global mortality was 7 percent. The diagnostic yield of BC was only 8.2 percent (20 patients). Mortality was significantly higher in patients with positive BC (20 percent) than in those with negative BC (5.8 percent). In only one of the 20 patients with positive BC (0.4 percent of total study population), attending physicians changed empiric antimicrobial therapy based on these results. Conclusions: This study confirms that the diagnostic yield of BC in CAP hospitalized patients is low, that mortality in bacteremic patients is high and suggests that clinical usefulness of BC to guide changes on empiric antimicrobial therapy is limited, in part because attending physicians seldom use such information