Photon-Induced Quantum Oscillations of the Terahertz Conductivity in Graphene.

In this work, we present a theory that is able to explain the nonmonotonic decreasing behavior (observed in experimental data1-12) of the graphene terahertz conductivity with the increase of the field frequency. In this connection, the displacement of the structure of topological states inside the energy band gap, which appears in graphene due to the strong photon-electron coupling, and the narrowing of this gap, as result of electron transitions from bound photon-dressed electron states to extended states outside the energy gap driven by the field frequency, lead to a periodic change of singularities near the edge of the band gap, resulting in subtle quantum oscillations of the dynamical terahertz conductivity. This quantum contribution complements the Drude response, which fits the spectral range. On the other hand, the scattering processes by impurities favor interband transitions, suppressing this way intraband terahertz absorptions, which are related to optical transitions from inside to outside the gap.

[Risk factors associated with the conformation of the medial longitudinal arch and the symptomatic flat foot in a metropolitan school population in Mexico]. / Factores de riesgo asociados a la conformación del arco longitudinal medial y del pie plano sintomático en una población escolar metropolitana en México.

INTRODUCTION: The investigation on the medial longitudinal arch is aimed at addressing the diagnostic problems of flat foot. The diagnosis is currently based on clinical tests and the appropriate identification of both postural and gait abnormalities. Risk factors are associated with pre-school ages, but there is no adequate analysis of such factors during school ages, when the longitudinal arch reaches its conformational maturity. MATERIAL AND METHODS: Probabilistic methods were used to obtain a sample of 476 patients from elementary schools in the Federal District and the state of Puebla. Once the approval of the research committee was obtained, an analytical, prospective, cross-sectional study was conducted. Anthropometric measurements were performed, together with anamnesis, physical exam of the students, and conventional wet footprint analysis in a standardized and duplicate way. RESULTS: Of the 476 patients, 101 had flat foot (21.2%) and 49 of them had pain symptoms in the feet, knees or both (48.5%), accounting for 10.2% of the patients examined. Forefoot pronation and valgus hindfoot resulted in an increased risk of symptomatic flat foot in the school population in the study. CONCLUSIONS: In cases of flat or cavus foot, the presence of foot and/or knee pain symptoms in the school population was associated in a statistically significant way with one or more of the factors analyzed (overweight, genu valgus, valgus hindfoot, forefoot pronation and claw toes). Girls with such factors had a 3-7 higher chance of having symptomatic flat foot.

Prótesis esofágicas / Esophageal prosthesis

El tratamiento paliativo endoscópico de neoplasias esofágicas avanzadas obstructivas que producen disfagia, episodios de broncoaspiración desnutrición o fístulas, incluye la dilatación endoscópica procedimiento de instalación de endoprótesis. Estos métodos son de bajo costo y pueden estar disponibles con facilidad en las unidades de endoscopía. Existen múltiples diferentes diseños de endoprótesis con ventajas y desventajas. Las de tipo metálico auto expandibles y las plásticas o de Tygon. Se describe la técnica para la instalación endoscópica de endoprótesis paso a paso. Existen complicaciones que pueden evitarse o resolverse tales como dolor torácico, oclusión debida a dieta inadecuada, perforación, fístula, sangramiento y desplazamiento ya sea proximal o distal de la prótesis como también enfermedad por reflujo relacionada con prótesis de esófago distal. La sobrevida y calidad de vida de pacientes con neoplasias avanzadas obstructivas pueden ser mejores con endoprótesis.

La vitamina C y sus propiedades antimutagénicas / The antimuthagenic properties of vitamin C

Se efectuó el análisis de algunas características de la vitamina C. Para ello se consideraron sus propiedades químicas y biológicas así como su impacto en la salud. Se revisaron las principales evidencias sobre su capacidad antimutagénica (y potencialmente anticarcinogénica) en diversos organismos y sistemas de prueba, y se consideró la posible aplicación en el humano

Niveles de carboxihemoglobina en donadores de sangre y de monóxido de carbono atmosférico en un área de la ciudad de México / Levels of carboxyhemoglobin in blood donors and of atmospheric carbon monoxide in a Mexico City area

La ciudad de México, con una altura sobre el nivel del mar de 2,240 m, ha alcanzado un elevado nivel de contaminación ambiental. El monóxido de carbono (CO) es uno de los principales contaminantes con capacidad de producir enfermedad cardiovascular de tipo isquémico o de agravar las existentes. El objetivo de este estudio fue conocer qué niveles de carboxihemoglobina (COHb), tiene los donadores de sangre que acuden al Instituto Nacional de Cardiología "Ignacio Chávez" de la ciudad de México, y qué niveles de monóxido de carbono se respiran en la atmósfera que hay en dicho Instituto. De mayo a junio de 1994, se analizaron los niveles venosos de COHb en 186 voluntarios donadores de sangre, y se midió el monóxido de carbono atmosférico en forma cotidiana durante el mismo periodo de tiempo, dentro de la Unidad Coronaria (UC) y en la azotea del 5º piso del Instituto a una distancia aproximada de 300 m de una vía con alto flujo vehicular (periférico sur). Los niveles de COHb en los fumadores fueron de 2.4 ñ 1.4 por ciento, y en los no fumadores de 1.5 ñ 0.6 por ciento, p= 0.002, cifra mucho más alta a la que se tiene de la producción endógena de este gas (0.5 por ciento), pero similar a la informada en otras ciudades del planeta. Los niveles de CO atmosférico nunca sobrepasaron las 4 partes por millón (ppm) (máximo pemitido por la Secretaría de Salud: 11 ppm), Los niveles de COHb no correlacionan con los parámetros estudiados: ocupación laboral, zona de la ciudad en que se habita o trabaja, medio de transporte usado para llegar al Instituto y número de kilómetros recorridos el día antes de la toma de la muestra, pero sí con el tabaquismo. Niveles de CO como los que se respiran en el aire de la UC y en la azotea del Instituto Nacional de Cardiología, no constituyen un peligro para la salud.

The incidence of protein C deficiency in thrombosis-related portal hypertension.

OBJECTIVE: To know the incidence of protein C deficiency associated with noncirrhotic, thrombosis-related portal hypertension. METHODS: Thirty-six patients were studied who had thrombosis-related portal hypertension diagnosed by means of hepatic venography or abdominal echocardiography or during abdominal surgery. Liver disease was excluded in 20 patients based on normal liver function tests and normal histology on liver biopsy. At the time of protein C assays, these patients were not receiving oral anticoagulation, and, in those recently diagnosed, the assays were performed more than 14 days after the last thrombotic event. Antigenic and functional assays for protein C were performed by ELISA and chromogenic assay, respectively. RESULTS: We found 11 patients with protein C deficiency who had a median age of 28 yr (range 19-55 yr) at time of diagnosis. Five patients had a history of systemic thromboembolism, and upper GI bleeding was the most frequent symptom related to portal hypertension (six cases). Antigenic protein C levels were measured in nine of the 11 patients (mean 31.88%, range 10-49%). Functional protein C level was assayed for all 11 patients (mean 40.90%, range 15-58%). After diagnosis, all patients received oral anticoagulants (ideally International Normalized Ratio: 2-3). CONCLUSION: We suggest that protein C screening should be performed in patients with thrombosis-related portal hypertension.

[Treatment of chronic refractory idiopathic thrombocytopenia purpura. 10 years experience at the Salvador Zubiran National Institute of Nutrition]. / Tratamiento de la púrpura trombocitopénica idiopática crónica refractaria. Experiencia de diez años en el Instituto Nacional de la Nutrición Salvador Zubirán.

A total of 126 patients with chronic idiopathic thrombocytopenic purpura were diagnosed from January 1980 to January 1990 in our institute. In this group of patients, 21 were refractory to prednisone therapy, splenectomy or both, or had had a relapse after a good response with these treatments. They were given other therapies. There was enough information for evaluation in 16 of the 21 patients. The treatment responses were classified according to the post-therapy platelet counts: complete response (CR) = > 150 x 10(9)/L for more than three months; partial response (PR) = 50-150 x 10(9)/L for more than three months; any response (AR) = CR + PR; no response (NR) = < 50 x 10(9)/L. There were 15 women and one male. The median age was 41 years (range 11 to 65). 6-mercaptopurine was given in all patients with CR = 31.2%, PR = 18.8%, AR = 50% and NR = 50%. Seven patients received cyclophosphamide with CR = 28.6%, PR = 14.3%, AR = 42.9% and NR = 57%. Vincristine was given in four patients with only one PR. Interferon alpha 2B was given in four patients with two transitory PR. One patient received colchicine and vitamin C without response. It is concluded that 6-mercaptopurine and cyclophosphamide are useful drugs in refractory thrombocytopenic purpura.

[Non-Hodgkin's lymphoma secondary to Hodgkin's disease treated with chemo- and radiotherapy. Report of a case]. / Linfoma no Hodgkin secundario a enfermedad de Hodgkin tratada con quimio- y radioterapias. Informe de un caso.

In 18 years of experience in the use of combined chemotherapy in Hodgkin's disease at the Instituto Nacional de la Nutrición Salvador Zubirán, the first case of non-Hodgkin's lymphoma secondary to Hodgkin's disease was identified. The patient was a 23 year old male who initially developed a nodular sclerosis type of Hodgkin's disease. Three years later, the biopsies showed lymphocyte predominance type of Hodgkin's disease. Finally, one year later, the patient developed a diffuse small cleaved cell lymphoma. Non-Hodgkin's lymphoma occurring in patients treated with combined chemotherapy and radiotherapy after Hodgkin's disease is a rare complication. We believe that the genesis of a second neoplasm in these cases may be due to both disturbances in the cellular immunity intrinsic to Hodgkin's disease and the treatment with combined chemotherapy and radiotherapy.

Long-term results of high-dose methylprednisolone in aplastic anemia.

Four males and two females, aged 13 to 57 years (median 22 years), with acquired severe aplastic anemia (AA) were treated with intravenous bolus of high doses of 6-methylprednisolone (MPL). Patients received MPL within a 30-day period at a dose of 20 mg/kg/day (3 days), 10 mg/kg/day (4 days), 5 mg/kg/day (4 days), 2 mg/kg/day (9 days), and 1 mg/kg/day (10 days). Within the first 3 months following MPL therapy, a response rate of 83%, assessed by means of increase in reticulocytes, neutrophils or platelets, was recorded in the group: two cases showed partial response and three improvement. The 3-month, and 1-, 2- and 3-year survival of the group was 67%, 50%, 33% and 33%, respectively. Neither the presence of reticulocytopenia or thrombocytopenia prior MPL therapy, nor age, gender, etiology of AA or time between diagnosis and initiation of MPL influenced survival. In contrast, neutrophil counts before MPL treatment had a strong prognostic value. Patients with less than 0.5 x 10(9)/L neutrophils had a median survival of 4.2 months (range 1.2 to 5.2 months) as compared to the 36.1 months median survival (range 12.1 to 36.8 months) of patients whose neutrophil counts were greater than 0.5 x 10(9)/L. Follow-up data suggest that the administration of androgens two months after MPL therapy did not modify survival. It is concluded that high-dose MPL is useful in the treatment of some patients with acquired severe AA, particularly in those with greater than 0.5 x 10(9)/L neutrophils who are not candidates for bone marrow transplantation.

[Control of oral anticoagulation. Current concepts]. / El control de la anticoagulación oral. Conceptos actuales.

The main objective of this short review is to bring into focus the most relevant of the recent advances in prothrombin time standardization and analyze the recommendations of the World Health Organization (WHO) for monitoring patients with thrombotic disorders under treatment with oral anticoagulant drugs. The prothrombin time (PT) is indicative of the proper therapeutic range in patients receiving oral anticoagulant drugs; however the reliability of the results will depend on the source and nature of the thromboplastin used. Different normal and therapeutic rangers are frequently observed when different brands of thromboplastin reagents and/or methods are used. The WHO, in conjunction with the International Committee of Thrombosis and Hemostasis and the International Committee of Standardization in Hematology, has recommended a calibration scheme for thromboplastin standardization with special reference for anticoagulant monitoring. Instead of reporting patient values, either in seconds or percent activity, WHO recommends the PT results in terms of an international normalized ratio (INR). This is obtained by formula: INR = RC in which R is the patient's PT and C is the international sensitivity index (ISI) of the thromboblastine employed. The INR represents the PT that would be obtained if it were performed with the WHO thromboplastin reference preparation. We suggest that these new concepts should be implemented by both laboratory and clinical professionals with the purpose of improving the effectiveness and safety of oral anticoagulation.

Comparison of colony-stimulating activities for evaluating in vitro granulomonopoiesis in normal subjects and in patients with myeloid leukemias

El crecimiento in vitro de unidades formadoras de colonias granulomonocíticas (UFC-GM) en sangre periférica (SP) y médula ósea (MO) humana requiere de fractores estimuladores denominados actividad estimuladora de colonias (AEC). El ensayo de Pike & Robinson emplea como fuente de AEC capa alimentadora (CA) compuesta por leucocitos de SP inmovilizados en agar. No obstante que este ensayo de bicapa presenta desventajas técnicas es ampliamente utilizado. Los sobrenadantes tisulares y celulares con actividad biológica para la UFC-GM, también conocidos como medios condicionados (MC), eliminan lsos incovenientes teécnicos de la estimulación con CA. En el presente trabajo se prepararon dos MC, uno de CA (MC-CA) y otro de leucocitos estimulados con fitohemaglutinina (MC-LEF). La AEC de ambos MC se comparó con la producida por la CA. Las tres AEC, evaluadas por el número de racimos (agregados celulares con 3 a 39 células) y de colonias (agregados celulares con -> 40 células) presentes en el cultivo, se probaron en células obtenidas de SP de 17 individuos sanos, y en células de SP (17 muestras) y MO (12 muestras) de enfermos con leucemias mieloides. Se encontró que el MC-CA indujo un número significativamente menor de agregados celulares tanto en muestras de sujetos normales como de enfermos leucémicos al compararlo con el ensayo de CA. En muestras de pacientes con leucemia, el crecimiento clonal mediado por el MC-LEF fue similar al encontrado con CA. En cambio, la adición de MC-LEF a muestras de sujetos sanos dio como resultado un número promedio de colonias significativamente menor al observado con CA. Estos resultados indican que el MC-CA es una fuente inapropiada de AEC para muestras provenientes de sujetos normales y de pacientes leucémicos, mientras que la AEC derivada del MC-LEF mantiene adecuadamente el crecimiento de UFC-GM en muestras de enfermos con leucemia, pero no en muestras de personas normales. Basados en estos hallazgos y en los incovenientes técnicos del ensayo de Pike & Robinson, se concluye que el MC-LEF permite una mejor evaluación de la granulomonopoyesis in vitro en pacientes con leucemias mieloides

[The electrocardiogram of high frequency in the evaluation of hypertensive cardiopathy]. / El electrocardiograma de alta frecuencia en la valoración de la cardiopatía hipertensiva.

The High-Frequency ECG was studied in 78 patients with systemic arterial hypertension and in 10 normal subjects. The study has shown: a) the P wave is altered initially, according to the disturbances in the myocardial complicance; b) the signs of LVH are mainly: delayed in the appearance of the intrinsecoid deflection, abnormal left direction of vector 3, left electrical systole diminished and counter clockwise rotation; c) the exhaustion fase is represented by increased of the electrical systole, delay in the duration of the intrinsecoid deflection and by primary disturbances of repolarization. The relationships between the ECG and the hymodynamic and metabolic disturbances, are discussed.