Evaluation of BACTEC™ MGIT™ 960 and the nitrate reductase assay in the National Laboratory Network of Colombia.

SETTING: The Mycobacteria Group of the National Reference Laboratory, National Laboratory Network, National Institute of Health and the Public Health Laboratories of Antioquia, Atlántico and Valle del Cauca, Colombia. OBJECTIVE: To compare BACTEC™ MGIT™ (Mycobacteria Growth Indicator Tube) 960 and the nitrate reductase assay (NRA) with the proportion method on Löwenstein-Jensen medium and to determine resistance to first-line anti-tuberculosis drugs. METHODS: Evaluation of diagnostic assays using time-adjusted convenience sampling. We analysed 183 isolates of Mycobacterium tuberculosis to compare MGIT 960 and NRA with the proportion method. RESULTS: MGIT 960 had a sensitivity and specificity of 90% for isoniazid (INH), and respectively 100% and 99.4% for rifampicin (RMP). NRA had a sensitivity and a specificity of respectively 86% and 94.7% for INH and 100% and 99% for RMP. CONCLUSION: Given its high sensitivity and specificity, and easy accessibility and interpretation of results, the NRA should be implemented in the National Laboratory Network for the detection of resistance to INH and RMP.

Specific dose-dependent damage of Lieberkühn crypts promoted by large doses of type 2 ribosome-inactivating protein nigrin b intravenous injection to mice.

Nigrin b is a non-toxic type 2 ribosome-inactivating protein as active as ricin at ribosomal level but 10(5) and 5 x 10(3) times less toxic for animal cell cultures and mice, respectively, than ricin. The purpose of the present study was to analyze the effects of intravenous injection of large amounts of nigrin b to the mouse. Injection through the tail vein of 16 mg/kg body weight killed all mice studied before 2 days. Analysis of several major tissues by light microscopy did not reveal gross nigrin b-promoted changes, except in the intestines which appeared highly damaged. As a consequence of the injury, the villi and crypt structures of the small intestine disappeared, leading to profuse bleeding and death. In contrast, intravenous injection of 5 mg/kg body weight was not lethal to mice but did trigger reversible toxic effects. In both cases, lethal and sub-lethal doses, the target of nigrin b appeared to be the highly proliferating stem cells of the intestinal crypts, which had undergone apoptotic changes. In contrast to nigrin b, the injection of 3 mug/kg of ricin kills all mice in 5 days but does not trigger apoptosis in the crypts. Therefore, the effect seen with sub-lethal nigrin b concentrations seems to be specific. Nigrin b killed COLO 320 human colon adenocarcinoma cells with an IC(50) of 3.1 x 10(-8) M and the effect was parallel to the extent of DNA fragmentation of these cells. Accordingly, despite the low general toxicity exerted by nigrin b as compared with ricin, intravenous injection of large amounts of nigrin b is able to kill mouse intestinal stem cells without threatening the lives of the animals, thereby opening a door for its use for the targeting of intestinal stem cells.

Non-toxic type 2 ribosome-inactivating proteins (RIPs) from Sambucus: occurrence, cellular and molecular activities and potential uses.

Ribosome-inactivating proteins (RIPs) are a family of enzymes that trigger the catalytic inactivation of ribosomes. The most known member of the family is the highly poisonous two-chain ricin isolated from Ricinus communis L. Sambucus species contain a number of two-chain RIPs structurally and enzymatically related to ricin which have the noteworthy feature that, having an enzymatic activity on ribosomes, leading to the inhibition of protein synthesis, higher than ricin, they are lacking of the tremendous unspecific toxicity of ricin. Therefore, they have been called non-toxic type 2 RIPs. The most representative and studied members are nigrin b present in the bark of the common (black) elder Sambucus nigra L. and ebulin 1 present in the leaves of the dwarf elder Sambucus ebulus L. The molecular basis for the low unspecific activities of nigrin b and ebulin 1 as compared with ricin seems to be related with single changes of amino acids in the high affinity sugar binding sites of the B chains. These changes determine the intracellular traffic of these proteins and thus the cellular toxicity. Conjugation ofnigrin b or ebulin 1 to either transferrin or monoclonal antibodies provided highly active conjugates targeting cancer. Thus these non-toxic type 2 RIPs are promising tools for cancer therapy.

Cr(VI) reduction by sulfidogenic and nonsulfidogenic microbial consortia.

In time course experiments, bacterial community compositions were compared between a sulfidogenic and two nonsulfidogenic Cr(VI)-reducing consortia enriched from metal-contaminated sediments. The consortia were subjected to 0 and 0.85 mM or 1.35 mM Cr(VI), and Cr(VI) reduction, growth, and denaturing gradient gel electrophoresis profiles of PCR products of small-subunit (16S) ribosomal genes were compared. Results showed that although Cr(VI) was completely reduced by the three consortia, Cr(VI) inhibited cell growth, with sulfate-reducing bacteria being particularly sensitive to Cr(VI) toxicity relative to other bacteria in the consortia.

[Cognitive rehabilitation. Theoretical and methodological aspects]. / Rehabilitación cognitiva. Aspectos teóricos y metodológicos.

AIMS: The aim of this paper is to theoretically define some aspects related with cognitive rehabilitation, as well as the methodological principles needed to draw up a programme of rehabilitation for these functions. METHOD: We performed an analysis of the definitions developed by different contemporary authors, of the theoretical approaches to cognitive rehabilitation, and the modes and models of how the functions are organised within the brain. Lastly, we set out the fundamental methodological principles to be taken into account in the production of a cognitive intervention programme, and describe the advantages offered by computer aided procedures as compared to the conventional methods of rehabilitation. CONCLUSIONS: Cognitive rehabilitation is currently considered one of the most important tasks or directions in neuropsychology and a number of theoretical and methodological approaches have been developed to deal with it. Over the past few years there has been a notable increase in the number of studies carried out involving cognitive intervention, especially in patients who are carriers of brain injuries of a traumatic or vascular aetiology and which give rise to a collection of motor, sensory and cognitive disorders. The level of development achieved in the cognitive neurosciences and IT have contributed to the conventional methods being substituted by computer applications that allow greater effectiveness in the rehabilitating process

Rehabilitación cognitiva. Aspectos teóricos y metodológicos / Cognitive rehabilitation. Theoretical and methodological aspects

Objetivo. Definir teóricamente algunos aspectos relacionados con la rehabilitación cognitiva, así como los principios metodológicos necesarios para la elaboración de un programa de rehabilitación de estas funciones. Desarrollo. Se realiza un análisis de las definiciones desarrolladas por diferentes autores contemporáneos, los enfoques teóricos de la rehabilitación cognitiva, sus principales mecanismos y modalidades y los modelos de organización cerebral de las funciones. Finalmente se exponen los principios metodológicos fundamentales a tener presente para la realización de un programa de intervención cognitiva, y se describen las ventajas que proporciona el soporte informático con relación a los métodos convencionales de rehabilitación. Conclusiones. En la actualidad, la rehabilitación cognitiva se considera una de las tareas o direcciones más importantes de la neuropsicología y para su abordaje se han desarrollado múltiples enfoques teóricos y metodológicos. Durante los últimos años ha existido un notable auge en el desarrollo de estudios de intervención cognitiva, de manera especial en pacientes portadores de lesiones cerebrales de etiología traumática o vascular, las cuales ocasionan un conjunto de alteraciones motoras, sensoriales y cognitivas. El desarrollo alcanzado por las neurociencias cognitivas y la informática han contribuido a la sustitución de los métodos convencionales por programas informáticos que permiten mayor efectividad al proceso rehabilitador (AU)

Sensitivity of cancer cell lines to the novel non-toxic type 2 ribosome-inactivating protein nigrin b.

The cytotoxicity of the type 2 ribosome-inactivating proteins (RIPs) ricin and nigrin b was determined in a variety of cancer cells. Nigrin b, considered to be a novel non-toxic type 2 RIP as compared with ricin, was approximately 10(4)-10(5) times less toxic than ricin in all cancer cells studied, with the exception of melanoma cells. Cancer cells displayed considerable heterogeneity in their sensitivity to ricin, melanoma cells being the least sensitive. Rabbit polyclonal anti-nigrin b antibodies did not cross-react with ricin as analyzed by enzyme-linked immunosorbent assays. The low non-specific toxicity of nigrin b as compared with that of ricin and the lack of immunological cross-reaction between anti-nigrin b antibodies and ricin supports the use of nigrin b in the construction of cytotoxic conjugates as an alternative to ricin when anti-ricin antibodies are produced during cancer therapy.

[Usefulness of bone-marrow culture in the etiological diagnosis of septicemia]. / Utilidad del mielocultivo en el diagnóstico etiológico de la septicemia.

Considerations are made on the importance of septicemia and the difficulty for an early diagnosis in most patients. The great usefulness shown by bone-marrow culture in the diagnosis of typhoid fever is pointed out and it is considered that this procedure may lend great help in the etiologic diagnosis of general infections. Twenty patients with septicemia are analyzed and the frequency of bone-marrow culture and of blood culture positiveness are compared and it is found that the percentage is greater for the first than for the second.

[Blastic crisis and cerebral leukotaxis in a case of lymphoblastic acute leukemia]. / Crisis blástica y leucostásis cerebral en un caso de leucemia aguda linfoblástica

The present report deals with the case of an eleven-years-old child with acute lymphoblastic leukemia who showed blastic crises, leukostasis and cerebral hemorrhage. The pathogenesis of these complications is analyzed and some therapeutic rules are outlined.

[Hemangiolymphangioma of the abdominal cavity complicated with consumption coagulopathy]. / Hemangiolinfangioma de cavidad abdominal complicado con coagulopatía por consumo

A case of giant hemangiolymphangioma of abdominal cavity is reported. It showed severe bleeding from consumption coagulopathy and secondary fibrinolysis. (Kasabach-Merritt syndrome). A review is made of the production mechanism of coagulation abnormalities that may accompany vascular neoplasias, the usefulness of anticoagulants and the selective treatment in this type of disease.