Increased human pathogenic potential of Escherichia coli from polymicrobial urinary tract infections in comparison to isolates from monomicrobial culture samples

The current diagnostic standard procedure outlined by the Health Protection Agency for urinary tract infections (UTIs) in clinical laboratories does not report bacteria isolated from samples containing three or more different bacterial species. As a result many UTIs go unreported and untreated, particularly in elderly patients, where polymicrobial UTI samples are especially prevalent. This study reports the presence of the major uropathogenic species in mixed culture urine samples from elderly patients, and of resistance to front-line antibiotics, with potentially increased levels of resistance to ciprofloxacin and trimethoprim. Most importantly, the study highlights that Escherichia coli present in polymicrobial UTI samples are statistically more invasive (P<0.001) in in vitro epithelial cell infection assays than those isolated from monomicrobial culture samples. In summary, the results of this study suggest that the current diagnostic standard procedure for polymicrobial UTI samples needs to be reassessed, and that E. coli present in polymicrobial UTI samples may pose an increased risk to human health

The effects of stress on in vivo hippocampal CA1 synaptic dynamics and hippocampal learning and memory

Chronic stress is associated with impairments in learning and memory, as well as changes in dendritic structure and synaptic connections of the hippocampus, a brain region key for spatial and episodic learning and memory. However, the cellular- and circuit- level mechanisms by which stress-induced structural synaptic changes impair learning and memory are not yet clear. Structural changes have historically been studied mostly by ex vivo preparations, due to the necessity to sacrifice the subjects to quantify structural changes. This approach however, is limited in its temporal resolution and lacks the ability to study the dynamic response to stress within the same subjects. This is important because responses to stress and learning and memory are intrinsically dynamic processes and individuals may differ in their baseline dynamics based on a host of uncontrollable factors.In order to overcome these drawbacks, I employed deep brain 2-photon in vivo time lapse optical imaging to longitudinally study the dorsal hippocampal CA1 region in live mice. I used a transgenic mouse model where a green fluorescent protein targeted to the cytoplasm sparsely labels a subset of excitatory neurons (Thy1-GFPm line). This enabled me to visualize the structure and the spines ? protrusions on the dendrites where most of the excitatory synapses of excitatory neurons occur ? of CA1 pyramidal neuron?s basal dendrites, further allowing me to track structural synaptic changes upon multi-modal stress (MMS). MMS involves exposure of mice to multiple simultaneous stressors.In this work, I tracked synaptic dynamics over two weeks during baseline and acute and repeated MMS by deep brain 2-photon in vivo time lapse optical imaging of groups of Thy1-GFPm mice. This enabled me to investigate ? for the first time in vivo ? stress-induced changes in CA1 synaptic dynamics.With this approach I was able to determine that MMS results in disruption of homeostatic structural plasticity. In addition I found that MMS strongly alters dynamics of immature synapses by decreasing their survival. Conversely, recovery increased the survival of spines born after stress, demonstrating higher survival rates in comparison to internally controlled baseline survival.In addition, I observed that stress increased the distance between newly formed spines and decreased the distance between lost spines, supporting spatially modulated alterations.Finally, I investigated the extent to which acute MMS and recovery and repeated MMS impair CA1 dependent learning and recall by using the Morris Water Maze (MWM) spatial learning paradigm and observed an impairment in learning in both stress groups.Understanding how stress impacts the dynamics of synapses is important to elucidate the basic mechanisms by which stress impairs learning and memory and it will be important for the development of therapeutic interventions both in terms of time scales and targets

Notes on the Development of Immature BlackHeaded Grosbeaks (Pheucticus melanocephalus)

From April to September, 1945, and from April to June, 1946, a field study was undertaken on the natural history of the common black-headed grosbeak (Pheucticus melanocephalus) in the breeding season (Weston, 1947). The following discussion, related to the development of immature birds, covers but one phase of this study. Observations were in Strawberry Canyon, on the campus of the University of California, Alameda County, California. Eight nests were studied in detail, six in 1945 and two in 1946. The usual set of eggs in this species consists of three to four eggs. Occasionally sets of two and five eggs are recorded. A study of 192 nests from the literature and other sources disclosed a mean clutch size of 3.31 eggs. Incubation lasts twelve days as does the following nestling period. Data were gathered on the development of eleven nestlings

Notes on the Occurrence of Birds During the Winters of 1948-1950, in Northern Emmet County, Iowa

During the winters of 1947-1948, 1948-1949 and 1949-1950 the author gathered data on the occurrence of birds in northern Emmet County, Iowa. Although data were gathered from February through July of 1948 and January through May of 1949 and 1950, this paper, for convenience, includes only the winter periods prior to March 1. Twenty days were spent in the field in the winter period of 1948, 46 days during 1949 and 45 days during 1950