Proliferation of Legionella pneumophila as an intracellular parasite of the ciliated protozoan Tetrahymena pyriformis.

In a series of experiments, we have determined that Legionella pneumophila will proliferate as an intracellular parasite of the ciliated holotrich Tetrahymena pyriformis in sterile tap water at 35 degrees C. After 7 days of incubation, serpentine chains of approximately 10(3) L. pneumophila cells were observed throughout the cytoplasm of the protozoan infected initially with 1 to 30 L. pneumophila cells. The overall L. pneumophila population increased from ca. 1.0 X 10(2) to ca. 5.0 X 10(4) cells per ml in the coculture within this time frame. The interactions between the protozoan and the bacterium appear to depend upon their concentrations as well as temperature of incubation. L. pneumophila did not multiply in sterile tap water alone, in suspensions of lysed T. pyriformis, or in cell-free filtrates of a T. pyriformis culture. In addition to establishing an ecological model, we found that addition of T. pyriformis to environmental specimens served as an enrichment method that improved isolation of legionella from the specimens.     

Effect of supplementall-tyrosine on pigment production in cultures of the Legionnaires' disease bacterium

The etiologic agent of Legionnaires' disease grows on certain agar media. Cultures of this organism on supplemented Mueller-Hinton agar are characterized by the appearance of brown pigment in and around areas of bacterial growth. The major peptone source in Mueller-Hinton agar is an acid hydrolysate of casein. Legionnaires' disease bacterium also grows on a medium in which the peptone source is 0.25% yeast extract, but no pigment is produced. If the yeast extract agar is enriched withl-tyrosine, pigment formation can occur. Pigmentation of cultures of Legionnaires' disease bacterium may be mediated by a phenolo-monooxygenase, or tyrosinase.     

Resistance of Mycobacterium chelonei-like organisms to formaldehyde.

Mycobacterium chelonei-like organisms have been isolated from patients in two outbreaks of peritonitis involving chronic peritoneal dialysis machines routinely disinfected with 2 to 3% formaldehyde. Susceptibility studies revealed that water-adapted M. chelonei-like organism strains could survive 2 h of exposure to 10% formaldehyde.     

Evolutionary heritage shapes tree distributions along an Amazon‐to‐Andes elevation gradient

Understanding how evolutionary constraints shape the elevational distributions of tree lineages provides valuable insight into the future of tropical montane forests under global change. With narrow elevational ranges, high taxonomic turnover, frequent habitat specialization, and exceptional levels of endemism, tropical montane forests and trees are predicted to be highly sensitive to environmental change. Using plot census data from a gradient traversing > 3,000 m in elevation on the Amazonian flank of the Peruvian Andes, we employ phylogenetic approaches to assess the influence of evolutionary heritage on distribution trends of trees at the genus‐level. We find that closely related lineages tend to occur at similar mean elevations, with sister genera pairs occurring a mean 254 m in elevation closer to each other than the mean elevational difference between non‐sister genera pairs. We also demonstrate phylogenetic clustering both above and below 1,750 m a.s.l, corresponding roughly to the cloud‐base ecotone. Belying these general trends, some lineages occur across many different elevations. However, these highly plastic lineages are not phylogenetically clustered. Overall, our findings suggest that tropical montane forests are home to unique tree lineage diversity, constrained by their evolutionary heritage and vulnerable to substantial losses under environmental changes, such as rising temperatures or an upward shift of the cloud‐base.     

Large-Scale Patterns of Turnover and Basal Area Change in Andean Forests

General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century.     

Anaplastic thyroid cancer: outcomes of trimodal therapy

BackroundThe purpose of this study is to assess the impact of trimodal therapy [surgery, chemotherapy and external beam radiotherapy (EBRT)] in patients with anaplastic thyroid cancer (ATC) treated with curative intent.Materials and methodsRetrospective review of patients with ATC treated at a tertiary referral centre between January 2009 and June 2020. Data were collected regarding demographics, histology, staging, treatment and outcomes.ResultsSeven patients (4 female) were identified. Median age was 58 years (range 52–83 years). All patients received EBRT with concurrent doxorubicin. Six patients received surgery followed by chemoradiotherapy (CRT), and one underwent neoadjuvant CRT followed by surgery. Median radiological tumour size was 50mm (range 40–90 mm). Six patients had gross extrathyroidal extension and three had N1b disease. Prescribed radiotherapy schedules were 46.4 Gy in 29 bidaily fractions (n = 2, treated 2010), 60 Gy in 30 daily fractions (n = 2), 66 Gy in 30 fractions (n = 2) and 70 Gy in 35 fractions (n = 1; patient received neoadjuvant CRT). CRT was discontinued early for two patients due to toxicities. At median follow up of 5.8 months, 42.9% (3/7) patients were alive and disease-free. Only one patient developed a local failure. Three patients died from distant metastases without locoregional recurrence.ConclusionsDespite poor prognosis of ATC, selected patients with operable tumours may achieve high locoregional control rates with trimodal therapy, with possibility of long-term survival in select cases.     

Decelerating growth in tropical forest trees

The impacts of global change on tropical forests remain poorly understood. We examined changes in tree growth rates over the past two decades for all species occurring in large (50-ha) forest dynamics plots in Panama and Malaysia. Stem growth rates declined significantly at both forests regardless of initial size or organizational level (species, community or stand). Decreasing growth rates were widespread, occurring in 24–71% of species at Barro Colorado Island, Panama (BCI) and in 58–95% of species at Pasoh, Malaysia (depending on the sizes of stems included). Changes in growth were not consistently associated with initial growth rate, adult stature, or wood density. Changes in growth were significantly associated with regional climate changes: at both sites growth was negatively correlated with annual mean daily minimum temperatures, and at BCI growth was positively correlated with annual precipitation and number of rainfree days (a measure of relative insolation). While the underlying cause(s) of decelerating growth is still unresolved, these patterns strongly contradict the hypothesized pantropical increase in tree growth rates caused by carbon fertilization. Decelerating tree growth will have important economic and environmental implications.     

IFITM3 inhibits influenza A virus infection by preventing cytosolic entry

To replicate, viruses must gain access to the host cell's resources. Interferon (IFN) regulates the actions of a large complement of interferon effector genes (IEGs) that prevent viral replication. The interferon inducible transmembrane protein family members, IFITM1, 2 and 3, are IEGs required for inhibition of influenza A virus, dengue virus, and West Nile virus replication in vitro. Here we report that IFN prevents emergence of viral genomes from the endosomal pathway, and that IFITM3 is both necessary and sufficient for this function. Notably, viral pseudoparticles were inhibited from transferring their contents into the host cell cytosol by IFN, and IFITM3 was required and sufficient for this action. We further demonstrate that IFN expands Rab7 and LAMP1-containing structures, and that IFITM3 overexpression is sufficient for this phenotype. Moreover, IFITM3 partially resides in late endosomal and lysosomal structures, placing it in the path of invading viruses. Collectively our data are consistent with the prediction that viruses that fuse in the late endosomes or lysosomes are vulnerable to IFITM3's actions, while viruses that enter at the cell surface or in the early endosomes may avoid inhibition. Multiple viruses enter host cells through the late endocytic pathway, and many of these invaders are attenuated by IFN. Therefore these findings are likely to have significance for the intrinsic immune system's neutralization of a diverse array of threats.     

O‐8FALSE NEGATIVE BRONCHIAL CYTOLOGY

Introduction: BK virus nephropathy is an emerging cause of renal transplant failure accounting for allograft loss in 45–50% of recipients between 2–60 months post‐transplantation. The Renal Transplant Unit in Royal Free Hospital has devised a local surveillance programme for screening renal transplant patients at weekly intervals by urinary cytology (UC) and electron microscopy (EM), and confirmation of positive results by plasma PCR and allograft biopsy. Objective: (i) To monitor the implementation of local guidelines; (ii) To compare UC with EM and (iii) To identify areas for improvement. Methods: Decoy cell and EM positive cases were retrieved from the WinPath database for new renal transplant recipients (n = 55) during 1^st November 2004 to 31^st October 2005 in Royal Free Hospital. Plasma PCR was retrieved for positive cases. Results: Up to eight samples were sent for UC at random intervals from 47 patients, and up to 7 were sent for EM from 42 patients. Eleven were UC‐positive and one was EM‐positive. PCR was not requested in UC‐positive cases and 3 out of 10 were positive retrospectively. The EM‐positive case was PCR‐positive but UC‐negative. Discussion: Urine Cytology is more appropriate and cost effective for screening than Electron Microscopy. During the period covered by this audit, samples were sent in an inconsistent fashion after allograft dysfunction rather than for screening. A screening protocol has been agreed and a re‐audit is planned.     

Elevated oxygen uptake and high rates of nitrogen excretion in early life stages of the cobia Rachycentron canadum (L.), a fast-growing subtropical fish

Physiological energetics of cobia Rachycentron canadum were quantified for 18 to 82 days post-hatch (dph) hatchery-reared juveniles to better understand energy transformation and its implications in growth and survival. Mean oxygen consumption rates ( ; mg O₂ h⁻¹) of fish fed ad libitum and fish that were starved significantly increased with increasing wet mass (M; g), = 1·4291 M ^0·8119 and = 1·1784 M ^0·7833, respectively, with a significant reduction in mean metabolic rates of starved fish (19 to 27% specific dynamic action; SDA). Total ammonia nitrogen excretion rates ( A _MM, μmol h⁻¹) also scaled with M and significantly decreased after starvation. Mean mass-specific A _MM and urea excretion rates are the highest reported in the literature, with urea accounting for approximately half the total nitrogen excretion measured in both fed and starved fish. Relatively high energetic rates may allow cobia to develop rapidly into pre-juveniles and be less susceptible to predation and starvation at a comparatively early age.