Regulation and function of Bcl-2 during differentiation-induced cell death in HL-60 promyelocytic cells

Polymorphonuclear leukocytes are generated by differentiation of early myeloid precursors. Once fully differentiated, blood neutrophils are programmed to die rapidly and are removed by tissue macrophages. In normal myeloid cells, the death mechanism seems to be coupled to the differentiation pathway and is accomplished by a process termed apoptosis. In the present study, we have examined the role of Bcl-2 in the differentiation pathways of the promyelocytic cell line HL-60. Treatment of HL-60 with retinoic acid or phorbol ester, which induced neutrophil or macrophage-like cell differentiation, respectively, resulted in progressive loss of cellular viability and internucleosomal DNA degradation. In HL-60, differentiation and apoptosis were coupled to down-regulation of the Bcl-2 protein. Overexpression of Bcl-2 by gene transfer inhibited apoptosis triggered by terminal differentiation of HL-60. Yet, Bcl-2 did not alter the expression of surface markers or other phenotypic changes that are induced upon myeloid differentiation. In contrast to HL-60, another immature myeloid cell line, K562, did not produce Bcl-2 but expressed a related protein, Bcl-xL, that functions as a repressor of apoptotic cell death. K562 has been shown to be relatively resistant to a variety of apoptotic stimuli. Incubation of HL-60 and K562 with inhibitors of macromolecular synthesis induced apoptosis, which appeared earlier in HL-60 than in K562. Interestingly, Bcl-2 overexpression protected K562 cells from apoptosis induced by inhibitor of macromolecular synthesis but it had little or no effect on HL-60 cells. We conclude that although differentiation and apoptosis proceed simultaneously, they can be uncoupled by expression of Bcl-2. Down-regulation of Bcl-2 appears to be part of the differentiation pathway and may serve to facilitate the apoptotic response.     

Cross-language synonyms in the lexicons of bilingual infants: one language or two?

This study tests the widely-cited claim from Volterra & Taeschner (1978), which is reinforced by Clark's PRINCIPLE OF CONTRAST (1987), that young simultaneous bilingual children reject cross-language synonyms in their earliest lexicons. The rejection of translation equivalents is taken by Volterra & Taeschner as support for the idea that the bilingual child possesses a single-language system which includes elements from both languages. We examine first the accuracy of the empirical claim and then its adequacy as support for the argument that bilingual children do not have independent lexical systems in each language. The vocabularies of 27 developing bilinguals were recorded at varying intervals between ages 0;8 and 2;6 using the MacArthur CDI, a standardized parent report form in English and Spanish. The two single-language vocabularies of each bilingual child were compared to determine how many pairs of translation equivalents (TEs) were reported for each child at different stages of development. TEs were observed for all children but one, with an average of 30% of all words coded in the two languages, both at early stages (in vocabularies of 2-12 words) and later (up to 500 words). Thus, Volterra & Taeschner's empirical claim was not upheld. Further, the number of TEs in the bilinguals' two lexicons was shown to be similar to the number of lexical items which co-occurred in the monolingual lexicons of two different children, as observed in 34 random pairings for between-child comparisons. It remains to be shown, therefore, that the bilinguals' lexicons are not composed of two independent systems at a very early age. Furthermore, the results appear to rule out the operation of a strong principle of contrast across languages in early bilingualism.     

Diagnosis of transfusion-associated graft-versus-host disease by polymerase chain reaction in fludarabine-treated B-chronic lymphocytic leukaemia

Transfusion-associated graft-versus-host disease (TA-GVHD), has rarely been reported associated with B-chronic lymphocytic leukaemia (B-CLL). We report a patient diagnosed with B-CLL, previously treated with fludarabine, who developed TA-GVHD after being transfused during surgery for splenectomy. Diagnosis was confirmed by polymerase chain reaction (PCR) detection of donor DNA in the patient, by amplification of Y-chromosome sequence and analysis of minisatellite polymorphisms. B-CLL patients treated with fludarabine appear to be at risk for TA-GVHD and should be regarded as candidates for transfusions with irradiated blood products. This case illustrates that PCR is a rapid technique for the early diagnosis of TA-GVHD.     

The development and cross-validation of methods based on radioimmunoassay and LC/MS-MS for the quantification of the class III antiarrhythmic agent, MK-0499, in human plasma and urine

An analytical method based on radioimmunoassay (RIA) has been developed for the determination of the antiarrhythmic agent, MK-0499, in plasma and urine. Owing to the potency of the drug, the specificity of this assay in human plasma could not be adequately determined using conventional RIA procedures. A highly specific procedure, based on LC/MS-MS, was developed to cross-validate the RIA. The lower quantifiable limits of the RIA and LC/MS-MS-based methods were 0.05 and 0.013 ng ml-1, respectively. Cross-validation data, compared using paired student's t-test regression analysis, showed excellent correlation between methods. The mass spectrometric assay was also used to simultaneously measure plasma concentrations of unlabeled and 14C-labeled MK-0499 following administration of the drug at high specific activity to volunteers.     

Prevalence of Staphylococcus aureus among food handlers from a metropolitan university in Chile

BACKGROUND: An important agent of food intoxication is Staphylococcus aureus, that is able to produce enterotoxins. AIM: To detect Staphylococcus aureus contamination in cafeteria food handlers of a Chilean University. SUBJECTS AND METHODS: Nose, throat, hands and nail samples from 87 food handlers were obtained for microbiological examination. RESULTS: Fifty seven subjects (65.5%) were carriers of Staphylococcus aureus. Enterotoxigenic Staphylococcus aureus was found in 36 subjects (41%). The most frequently found enterotoxin was type B (18 samples) followed by type D (12 samples). Men bad a higher frequency of contamination than women (83 and 57% of positive samples respectively). CONCLUSIONS: The frequency of Staphylococcus aureus contamination among food handlers is high and should prompt personal and environmental hygienic measures.     

Laryngeal reinnervation: transposition of neuromuscular pedicles

Following Tucker's technique, a muscle-nerve pedicle implantation in the denervated posterior cricoarytenoid muscle was performed in five dogs. Results were evaluated after six months by videolaryngoscopy, evoked muscle action potentials and histomorphometric studies. Partial motion recovery of the reinnervated side was observed endoscopically in three dogs. Histomorphometric evaluation showed evidence of muscle reinnervation in all of the five dogs. However, no muscle action potentials were obtained in the posterior cricoarytenoid muscles after stimulation of the ansa hypoglossi branch. These data suggest that the ansa hypoglossi neuromuscular pedicle does not result in reinnervation, and that reinnervation of the posterior cricoarytenoid muscle may occur via other neuromuscular pathways.     

Hemagglutination patterns of uropathogenic Escherichia coli

An hemagglutination (HA) type system has been applied to demonstrate mannose sensitive (MS) and mannose resistant (MR) hemagglutination produced by Escherichia coli isolated from urinary tract infections. Hemagglutination types were obtained by the agglutination of different species of red cells -human, bovine, chicken and guinea pig- suspended in buffer phosphate (PBS), with and without mannose, with E. coli cells grown in CFA agar (Casamino acid 10 g, yeast extract 15 g, sodium chloride 2.5 g, potassium phosphate 8.7 g, magnesium sulfate 0.5 g, manganese chloride 0.005 g, agar 20 g). Salting out (hydrophobicity) and yeast agglutination assays were performed for a complete evaluation of results. The applicability of this system was based on the dates exhibited in Table 1. A significant proportion (45%) of the uropathogenic Escherichia coli strains showed RNNN HA patterns, and (16%) NNSS, and (15%) SNSS were also considered important. The application of this hemagglutination system on this kind of strains allowed the evaluation of the different types of hemagglutination and their relation with colonization capacity.     

Validation of an inhibition ELISA using a monoclonal antibody for foot-and-mouth disease (FMD) primary diagnosis

An inhibition ELISA (IH-ELISA) test for foot-and-mouth disease virus (FMDV) was validated using 106 epithelial samples from suspected cases of FMD in Argentina submitted to the Argentine National Diagnostics Laboratory (GELAB) over a period of 12 months and examined in parallel with the complement fixation test (CFT). IH-ELISA was found to be more sensitive, detecting 25% (26 samples) more FMDV positives than the CFT in original suspensions of field samples. The effect of storage conditions on 12S stability was examined. Plates stored at 4 degrees C blocked with 1% ovalbumin and plates stored at -20 degrees C with or without blocking buffer could be used for at least 90 days. When various brands of polystyrene plates were compared for 12ps adsorption it was found that those microplates of higher binding capacity were more efficient.