Acute leukemia in children: experience in Saskatchewan in 1966-72.

In 1966-72 in Saskatchewan there was a significant improvement in survival of patients up to 16 years old with acute leukemia treated intensively. The rate of complications was low. Attention to the emotional needs of the patients and parents and formation of parent mutual-support groups improved the acceptibility of intensive therapy.     

‘Morphological shifts’ in filamentous bacteria isolated from activated sludge processes

Summary This study aimed at isolating filamentous bacteria from full-scale activated sludge processes and studying them in pure culture. Three cultures were isolated using conventional microbiological techniques. The isolates were positively identified as Gordonia amarae, Thiothrix nivea and Type 1863/Acinetobacter spp., using fluorescent in situ hybridization (FISH) with 16S rRNA-targeted oligonucleotide probes. However, a ‘morphological shift’ from filamentous to single-cell form was observed in pure culture. The application of fluorescent in situ hybridization (FISH) showed filamentous bacteria to be much more diverse in their ability to adapt to their changing enviroments. Pure culture studies of filamentous bacteria form the basis for application in full-scale activated sludge plants. It therefore remains important that the taxonomic status of filamentous bacteria be determined.     

The foliar trichomes of Hypoestes aristata (Vahl) Sol. ex Roem. & Schult var aristata (Acanthaceae) a widespread medicinal plant species in tropical sub-Saharan Africa: with comments on its possible phylogenetic significance

The micromorphology of foliar trichomes of Hypoestes aristata var. aristata was studied using stereo, light and scanning microscopy (SEM). This genus belongs to the advanced angiosperm family Acanthaceae, for which few micromorphological leaf studies exist. Results revealed both glandular and non-glandular trichomes, the latter being more abundant on leaf veins, particularly on the abaxial surface of very young leaves. With leaf maturity, the density of non-glandular trichomes decreased. Glandular trichomes were rare and of two types: long-stalked capitate and globose-like peltate trichomes. Capitate trichomes were observed only on the abaxial leaf surface, while peltate trichomes were distributed on both adaxial and abaxial leaf surfaces.     

Homomeric ring assemblies of eukaryotic Sm proteins have affinity for both RNA and DNA. Crystal structure of an oligomeric complex of yeast SmF

Sm and Sm-like proteins are key components of small ribonucleoproteins involved in many RNA and DNA processing pathways. In eukaryotes, these complexes contain seven unique Sm or Sm-like (Lsm) proteins assembled as hetero-heptameric rings, whereas in Archaea and bacteria six or seven-membered rings are made from only a single polypeptide chain. Here we show that single Sm and Lsm proteins from yeast also have the capacity to assemble into homo-oligomeric rings. Formation of homo-oligomers by the spliceosomal small nuclear ribonucleoprotein components SmE and SmF preclude hetero-interactions vital to formation of functional small nuclear RNP complexes in vivo. To better understand these unusual complexes, we have determined the crystal structure of the homomeric assembly of the spliceosomal protein SmF. Like its archaeal/bacterial homologs, the SmF complex forms a homomeric ring but in an entirely novel arrangement whereby two heptameric rings form a co-axially stacked dimer via interactions mediated by the variable loops of the individual SmF protein chains. Furthermore, we demonstrate that the homomeric assemblies of yeast Sm and Lsm proteins are capable of binding not only to oligo(U) RNA but, in the case of SmF, also to oligo(dT) single-stranded DNA.     

ANATOMICAL AND METABOLIC RESPONSES TO WATERLOGGING AND SALINITY IN SPARTINA ALTERNIFLORA AND S. PATENS (POACEAE)

The effects of waterlogging and salinity (25 or 325 mol m ³ NaCl) stressors on the anatomy and metabolism of the marsh grasses 5. alterniflora Loisel. and S. patens Aiton (Muhl.) were investigated in a V factorial greenhouse experiment over 30 d. Waterlogging and salinity in combination resulted in anatomical and metabolic responses in both species. Waterlogging reduced soil redox potential and decreased root-specific gravity significantly in both species. The inadequacy of aerenchyma development under hypoxia to support aerobic root respiration in S. patens was indicated by significant increases in root alcohol dehydrogenase (ADH) activity of 1,752% and 420%, respectively, in the low and high salinity treatments. ADH activity was not increased significantly by flooding of S. alterniflora. Proline concentrations in roots and leaves were low at low salinities and increased significantly at high salinities in both species, but only under drained conditions. Decrease in leaf elongation by high salinity occurred in drained, but not flooded treatments in both species. Under flooded conditions, leaf elongation was significantly greater in S. alterniflora than S. patens. Greatest leaf elongation occurred in flooded low salinity S. alterniflora plants that had the least proline. Although both species are adapted to waterlogging and salinity, S. alterniflora appears to be more tolerant of reducing soil conditions and less responsive to higher salinity than S. patens.     

Arundo donax L. (Poaceae) — a C3 Species with Unusually High Photosynthetic Capacity

Gas exchange characteristics, chlorophyll a fluorescence and leaf water potential were investigated in the giant reed, Arundo donax, under natural conditions in an estuarine mangrove swamp in Durban, South Africa. Maximum photosynthetic CO₂ uptake ranged between 19.8 and 36.7 μmol m^?2 s^?1, depending on irradiance, and appeared to be regulated by leaf conductance. There was no saturation of CO₂ uptake or electron transport through PSII (ETR) with increasing irradiance up to 2500 μmol photons m^?2 s^?1. A linear relationship between CO₂ uptake, corrected for respiration (A), and ETR has only been reported for C₄ species and C₃ species when photorespiration is eliminated. From this relationship, it was calculated that 8.5 electrons were transported through PSII for the fixation of one mole of CO₂. Predawn leaf water potential was about ?0.5 MPa and decreased to ?1.5 MPa on a cloudy day and to ?2.1 MPa on a clear day. Diurnal change in leaf water potential had little influence on leaf conductance and hence CO₂ uptake. The molar water use efficiency (WUE) ranged between 4.1 and 9.3 μmol mmol^?1. Percentage photorespiration was between 36 and 39%.     

Nosocomial Outbreak of New Delhi Metallo-β-Lactamase-1-Producing Gram-Negative Bacteria in South Africa: A Case-Control Study

Objective

New Delhi metallo-β-lactamase (NDM)-producing Gram-negative bacteria have spread globally and pose a significant public health threat. There is a need to better define risk factors and outcomes of NDM-1 clinical infection. We assessed risk factors for nosocomial infection with NDM-1-producers and associated in-hospital mortality.

Methods

A matched case-control study was conducted during a nosocomial outbreak of NDM-1-producers in an adult intensive care unit (ICU) in South Africa. All patients from whom NDM-1-producers were identified were considered (n=105). Cases included patients admitted during the study period in whom NDM-1 producing Gram-negative bacteria were isolated from clinical specimens collected ≥48 hours after admission, and where surveillance definitions for healthcare-associated infections were met. Controls were matched for age, sex, date of hospital admission and intensive-care admission. Conditional logistic regression was used to identify risk factors for NDM-1 clinical infection and associated in-hospital mortality.

Findings

38 cases and 68 controls were included. Klebsiella pneumoniae was the most common NDM-1-producer (28/38, 74%). Cases had longer mean hospital stays (44.0 vs. 13.3 days; P < 0.001) and ICU stays (32.5 vs. 8.3 days; P < 0.001). Adjusting for co-morbid disease, the in-hospital mortality of cases was significantly higher than controls (55.3% vs. 14.7%; AOR, 11.29; P < 0.001). Higher Charlson co-morbidity index score (5.2 vs. 4.1; AOR, 1.59; P = 0.005), mechanical ventilation days (7.47 vs. 0.94 days; AOR, 1.32; P = 0.003) and piperacillin/tazobactam exposure (11.03 vs. 1.05 doses; AOR, 1.08; P = 0.013) were identified as risk factors on multivariate analysis. Cases had a significantly higher likelihood of in-hospital mortality when the NDM-1-producer was Klebsiella pneumoniae (AOR, 16.57; P = 0.007), or when they had a bloodstream infection (AOR, 8.84; P = 0.041).

Conclusion

NDM-1 infection is associated with significant in-hospital mortality. Risk factors for hospital-associated infection include the presence of co-morbid disease, mechanical ventilation and piperacillin/tazobactam exposure.