Total but not resting energy expenditure is increased in infants with ventricular septal defects

OBJECTIVE: The purpose of this study was to determine the effect of left-to-right shunting on the resting energy expenditure (REE), total energy expenditure (TEE), and energy intake in a group of 3- to 5-month-old infants with moderate to large unrepaired ventricular septal defects (VSDs) compared with age-matched, healthy infants. METHODS: Eight infants with VSDs and 10 healthy controls between 3 to 5 months of age participated in the study. Indirect calorimetry was used to measure REE and the doubly-labeled water method was used to measure TEE and energy intake. An echocardiogram and anthropometric measurements were performed on all study participants. Daily urine samples were collected at home for 7 days. Samples were analyzed by isotope ratio mass spectrometry. Data were compared using analysis of variance. RESULTS: No significant differences were found in REE (VSD, 42.2 +/- 8.7 kcal/kg/d; control, 43.9 +/- 14.1 kcal/kg/d) or energy intake (VSD, 90.8 +/- 19.9 kcal/kg/d; control, 87.1 +/- 11.7 kcal/kg/d) between the groups. The percent total body water was significantly higher in the VSD infants and the percent fat mass was significantly lower. TEE was 40% higher in the VSD group (VSD, 87.6 +/- 10.8 kcal/kg/d; control, 61.9 +/- 10.3 kcal/kg/d). The difference between TEE and REE, reflecting the energy of activity, was 2.5 times greater in the VSD group. CONCLUSIONS: REE and energy intake are virtually identical between the two groups. Despite this, infants with VSDs have substantially higher TEE than age-matched healthy infants. The large difference between TEE and REE in VSD infants suggests a substantially elevated energy cost of physical activity in these infants. These results demonstrate that, although infants with VSDs may match the energy intake of healthy infants, they are unable to meet their increased energy demands, resulting in growth retardation.     

Daptomycin tested against 915 bloodstream isolates of viridans group streptococci (eight species) and Streptococcus bovis

OBJECTIVES: To evaluate the activity of daptomycin tested against numerous species of viridans group streptococci and Streptococcus bovis, which are associated with wound infections, sepsis, cellulitis, endocarditis, abscesses and dental caries. The incidence of penicillin-resistant (non-susceptible) and MLS(B)-resistant strains among viridans group streptococci often varies by species. METHODS: The activity of daptomycin was compared with seven other antimicrobial classes using reference broth microdilution and disc diffusion methods tested against 915 bacteraemic isolates of streptococci (815 viridans group strains; 100 S. bovis). RESULTS: Among all species of viridans group streptococci and S. bovis, 99.9% of isolates were susceptible to daptomycin (MIC values, < or = 0.016-2 mg/L). In contrast, penicillin, erythromycin and tetracycline susceptibility varied widely between species. Erythromycin susceptibility was in the range 48.6-88.7%, penicillin susceptibility in the range 65.5-98.1% and tetracycline in the range 35.0-93.9%. The inter-method agreement between daptomycin and linezolid resistance (comparison agent) disc diffusion and broth microdilution test results was high, each showing near complete susceptibility (99.9%). CONCLUSIONS: Daptomycin is an active antimicrobial agent that has a usable potency against eight species of viridans group streptococci, as well as S. bovis, with all MIC values at < or =2 mg/L.     

In vitro and in vivo evaluations of A-80556, a new fluoroquinolone.

A-80556 is a novel fluoroquinolone with potent antibacterial activity against gram-positive, gram-negative, and anaerobic organisms. A-80556 was more active than ciprofloxacin, ofloxacin, lomefloxacin, and sparfloxacin against gram-positive bacteria. A-80556 was particularly active against Staphylococcus aureus (MIC for 90% of isolates [MIC90], 0.12 microgram/ml, relative to fluoroquinolone-susceptible strains) and Streptococcus pneumoniae (MIC90, 0.12 microgram/ml). A-80556 was also the most active of the quinolones tested against ciprofloxacin-resistant S. aureus, with an MIC90 of 4.0 micrograms/ml; that of ciprofloxacin was > 128 micrograms/ml. However, the significance of this activity is not known. A-80556 was slightly less active against Escherichia coli (MIC90, 0.06 microgram/ml) and other enteric organisms than ciprofloxacin (MIC90 for E. coli, < or = 0.03 microgram/ml). A-80556 was slightly less active against Pseudomonas aeruginosa (MIC90, 4.0 micrograms/ml) than ciprofloxacin (MIC90, 2.0 micrograms/ml) and more active against Acinetobacter spp. (respective MIC90s, 0.12 and 0.5 microgram/ml). A-80556 was also the most active compound against anaerobes. Against Bacteroides fragilis, the MIC90 of A-80556 was 2.0 micrograms/ml; that of ciprofloxacin was 16 micrograms/ml. The in vivo efficacy of A-80556 in experimental models with both gram-positive and gram-negative infections was consistent with the in vitro activity and pharmacokinetics and oral absorption in mice.     

Molecular basis of altered red blood cell membrane properties in Southeast Asian ovalocytosis: role of the mutant band 3 protein in band 3 oligomerization and retention by the membrane skeleton

Southeast Asian ovalocytosis (SAO) is an asymptomatic trait characterized by rigid, poorly deformable red cells that resist invasion by several strains of malaria parasites. The underlying molecular genetic defect involves simple heterozygous state for a mutant band 3 protein, which contains a deletion of amino acids 400 through 408, linked with a Lys 56-to-Glu substitution (band 3-Memphis polymorphism). To elucidate the contribution of the mutant SAO band 3 protein to increased SAO red blood cell (RBC) rigidity, we examined the participation of the mutant SAO band 3 protein in increased band 3 attachment to the skeleton and band 3 oligomerization. We found first that SAO RBC skeletons retained more band 3 than normal cells and that this increased retention preferentially involved the mutant SAO band 3 protein. Second, SAO RBCs contained a higher percentage of band 3 oligomer-ankyrin complexes than normal cells, and these oligomers were preferentially enriched by the mutant SAO protein. At the ultrastructural level, the increased oligomer formation of SAO RBCs was reflected by stacking of band 3-containing intramembrane particles (IMP) into longitudinal strands. The IMP stacking was not reversed by treating SAO RBCs in alkaline pH (pH 11), which is known to weaken ankyrin-band 3 interactions, or by removing the cytoplasmic domain of band 3 from SAO membranes with trypsin. Finally, we found that band 3 protein in intact SAO RBCs exhibited a markedly decreased rotational mobility, presumably reflecting the increased oligomerization and the membrane skeletal association of the SAO band 3 protein. We propose that the mutant SAO band 3 has an increased propensity to form oligomers, which appear as longitudinal strands of IMP and exhibit increased association with membrane skeleton. This band 3 oligomerization underlies the increase in membrane rigidity by precluding membrane skeletal extension, which is necessary for membrane deformation.     

Cytogenetic and histologic correlations in malignant lymphoma

Although a number of studies have indicated correlations between histologic subtypes of tumors and certain nonrandom chromosome changes, cytogenetic studies of lymphoma are in an early stage compared to those of leukemia. No comprehensive analysis of available data has so far been attempted in the literature either. Here we present an analysis of chromosome changes and their correlation with subtypes of lymphoma studied by conventional histology and cell surface markers, as observed in two sets of data: a group of 65 karyotypically abnormal tumors sequentially ascertained and studied by us during the period January 1, 1984 to April 30, 1985, and a larger data set derived by combining our data with those from two published series from the University of Minnesota that are comparable to our data. These combined data, which comprise the largest data set on the cytogenetics of lymphomas assembled so far, enabled a comprehensive analysis of correlation between chromosome change and tumor histology and the patterns of chromosome instability in these tumors. We found several significant associations, some previously described and others now recognized, between nonrandom chromosome gains, breaks, translocations, and deletions and histologic subtypes of tumors that characterize lymphomas. The data indicate that finding of chromosome breaks at certain sites (eg, 8q24, 14q32, 18q21) is of diagnostic value in dealing with cases of unusual lymphoma. Furthermore, nonrandom chromosome breakage exhibited three distinct patterns that reflected three levels of etiologically relevant genetic change.     

MicroRNAs (miR)-221 and miR-222, both overexpressed in human thyroid papillary carcinomas, regulate p27Kip1 protein levels and cell cycle

We have recently reported that MicroRNAs (miR)-221 and miR-222 were up-regulated in human thyroid papillary carcinomas in comparison with the normal thyroid tissue. Bioinformatic analysis proposed the p27(Kip1) protein, a key regulator of cell cycle, as a candidate target for the miR-221/222 cluster. Here, we report that the enforced expression of miR-221 and miR-222 was able to reduce p27(Kip1) protein levels in thyroid carcinoma and HeLa cells in the absence of significant changes in specific p27(Kip1) mRNA levels. This effect is direct as miR-221 and miR-222 negatively regulate the expression of the 3'-untranslated region-based reporter construct from the p27(Kip1) gene, and is dependent on two target sites in this region. Consistent with these results, an enforced expression of the miR-221 and miR-222 induced the thyroid papillary carcinoma cell line (TPC-1) to progress to the S phase of the cell cycle. It is likely that the negative regulation of p27(Kip1) by miR-221 and miR-222 might also have a role in vivo since we report an inverse correlation between miR-221 and miR-222 up-regulation and down-regulation of the p27(Kip1) protein levels in human thyroid papillary carcinomas. Therefore, the data reported here demonstrate that miR-221 and miR-222 are endogenous regulators of p27(Kip1) protein expression, and thereby, the cell cycle.     

Tcl1 protein functions as an inhibitor of de novo DNA methylation in B-cell chronic lymphocytic leukemia (CLL)

B-cell chronic lymphocytic leukemia (CLL) is the most common human leukemia. Deregulation of the T-cell leukemia/lymphoma 1 oncogene (TCL1) in mouse B cells causes a CD5(+) leukemia similar to aggressive human CLL. To examine the mechanisms by which Tcl1 protein exerts its oncogenic activity in B cells, we performed proteomics experiments to identify its interacting partners. We found that Tcl1 physically interacts with de novo DNA methylthansferases Dnmt3A and Dnmt3B. We further investigated the effects of Tcl1 up-regulation on the enzymatic activity of Dnmt3A and found that Tcl1 overexpression drastically inhibits Dnmt3A function. In addition, B cells from TCL1 transgenic mice showed a significant decrease in DNA methylation compared with WT controls. Similarly, CLL samples with high Tcl1 expression showed a decrease in DNA methylation compared with CLL samples with low Tcl1 expression. Given the previous reports of inactivating mutations of DNMT3A in acute myelogenous leukemia and myelodysplastic syndrome, our results suggest that inhibition of de novo DNA methylation may be a common oncogenic mechanism in leukemogenesis.