Taxonomy of the Sphaerostilbella broomeana-group (Hypocreales, Ascomycota).

Three new species, closely related to Sphaerostilbella broomeana, are described from the USA and India. These species form septate conidia from simple conidiophores with individual branches terminating in a single phialide and chlamydospores. Teleomorphs, known for S. broomeana and S. appalachiensis, are characterised by hairy perithecia and fusiform, apiculate, and conspicuously warted ascospores. This combination of characters distinguishes the S. broomeana-group from other members of Sphaerostilbella that all form gliocladium-type anamorphs and mostly grow on basidiomata of Stereum spp. Like in other species of the genus, the majority of hosts of the species described in this paper belong to wood-inhabiting taxa of Russulales. Sphaerostilbella broomeana had been recorded from a few regions in Europe and exclusively on Heterobasidion annosum. Herein, it is reported also from H. parviporum in many other localities and on H. insulare s.l. at the foothills of the Himalayas. Its sister species, found in the same region in northern India on another member of Russulales (Dichostereum effuscatum), is described as S. himalayensis. The two species described from North America colonize polypores from various taxa. Whereas S. appalachiensis occurs in eastern USA, with H. irregulare among its hosts, S. toxica is so far known only from two locations in eastern Texas, growing on Gloeophyllum striatum (Polyporales). Despite their great similarity in morphology and ITS rDNA, TEF1 sequences clearly distinguish these two North-American species. Moreover, the two strains of S. toxica appeared metabolically distinct as their organic extracts strongly inhibited the growth of human pathogenic microbes grown in vitro. Phylogenetic analysis of rDNA sequences supports monophyly of the genus Sphaerostilbella and the included S. broomeana-group, established here.

Single-room usage patterns and allocation decision-making in an Australian public hospital: a sequential exploratory study.

AIMS AND OBJECTIVES: The aims are to (1) measure occupancy rates of single and shared rooms; (2) compare single room usage patterns and (3) explore the practice, rationale and decision-making processes associated with single rooms; across one Australian public health service. BACKGROUND: There is a tendency in Australia and internationally to increase the proportion of single patient rooms in hospitals. To date there have been no Australian studies that investigate the use of single rooms in clinical practice. DESIGN: This study used a sequential exploratory design with data collected in 2014. METHODS: A descriptive survey was used to measure the use of single rooms across a two-week time frame. Semi-structured interviews were undertaken with occupancy decision-makers to explore the practices, rationale decision-making process associated with single-room allocation. RESULTS: Total bed occupancy did not fall below 99·4% during the period of data collection. Infection control was the primary reason for patients to be allocated to a single room, however, the patterns varied according to ward type and single-room availability. For occupancy decision-makers, decisions about patient allocation was a complex and challenging process, influenced and complicated by numerous factors including occupancy rates, the infection status of the patient/s, funding and patient/family preference. Bed moves were common resulting from frequent re-evaluation of need. CONCLUSION: Apart from infection control mandates, there was little tangible evidence to guide decision-making about single-room allocation. Further work is necessary to assist nurses in their decision-making. RELEVANCE TO CLINICAL PRACTICE: There is a trend towards increasing the proportion of single rooms in new hospital builds. Coupled with the competing clinical demands for single room care, this study highlights the complexity of nursing decision-making about patient allocation to single rooms, an issue urgently requiring further attention.

Hyaluronan deficiency due to Has3 knock-out causes altered neuronal activity and seizures via reduction in brain extracellular space.

Hyaluronan (HA), a large anionic polysaccharide (glycosaminoglycan), is a major constituent of the extracellular matrix of the adult brain. To address its function, we examined the neurophysiology of knock-out mice deficient in hyaluronan synthase (Has) genes. Here we report that these Has mutant mice are prone to epileptic seizures, and that in Has3(-/-) mice, this phenotype is likely derived from a reduction in the size of the brain extracellular space (ECS). Among the three Has knock-out models, namely Has3(-/-), Has1(-/-), and Has2(CKO), the seizures were most prevalent in Has3(-/-) mice, which also showed the greatest HA reduction in the hippocampus. Electrophysiology in Has3(-/-) brain slices demonstrated spontaneous epileptiform activity in CA1 pyramidal neurons, while histological analysis revealed an increase in cell packing in the CA1 stratum pyramidale. Imaging of the diffusion of a fluorescent marker revealed that the transit of molecules through the ECS of this layer was reduced. Quantitative analysis of ECS by the real-time iontophoretic method demonstrated that ECS volume was selectively reduced in the stratum pyramidale by ∼ 40% in Has3(-/-) mice. Finally, osmotic manipulation experiments in brain slices from Has3(-/-) and wild-type mice provided evidence for a causal link between ECS volume and epileptiform activity. Our results provide the first direct evidence for the physiological role of HA in the regulation of ECS volume, and suggest that HA-based preservation of ECS volume may offer a novel avenue for development of antiepileptogenic treatments.

Extracellular diffusion in laminar brain structures exemplified by hippocampus.

Numerous brain structures are composed of distinct layers and such stratification has a profound effect on extracellular diffusion transport in these structures. We have derived a more general form of diffusion equation incorporating inhomogeneities in both the extracellular volume fraction (α) and diffusion permeability (θ). A numerical solution of this equation for a special case of layered environment was employed to analyze diffusion in the CA1 region of hippocampus where stratum pyramidale occupied by the bodies of principal neurons is flanked by stratum radiatum and stratum oriens. Extracellular diffusion in the CA1 region was measured in vitro by real-time iontophoretic and real-time pressure methods, and numerical analysis found that stratum pyramidale had a significantly smaller extracellular volume fraction (α=0.127) and lower diffusion permeability (θ=0.327) than the other two layers (α=0.218, θ=0.447). Stratum pyramidale thus functioned as a diffusion barrier for molecules attempting to cross it. We also demonstrate that unless the detailed properties of all layers are taken into account when diffusion experiments are interpreted, the extracted apparent parameters of the extracellular space lose their physical meaning and capacity to describe any individual layer. Such apparent parameters depend on diffusion distance and direction, giving a false impression of microscopic anisotropy and non-Gaussian behavior. This finding has implications for all diffusion mediated physiological processes as well as for other diffusion methods including integrative optical imaging and diffusion-weighted magnetic resonance imaging.

Magnetization transfer effects on the efficiency of flow-driven adiabatic fast passage inversion of arterial blood.

Continuous arterial spin labeling experiments typically use flow-driven adiabatic fast passage inversion of the arterial blood water protons. In this article, we measure the effect of magnetization transfer in blood and how it affects the inversion label. We use modified Bloch equations to model flow-driven adiabatic inversion in the presence of magnetization transfer in blood flowing at velocities from 1 to 30 cm/s in order to explain our findings. Magnetization transfer results in a reduction of the inversion efficiency at the inversion plane of up to 3.65% in the range of velocities examined, as well as faster relaxation of the arterial label in continuous labeling experiments. The two effects combined can result in inversion efficiency reduction of up to 8.91% in the simulated range of velocities. These effects are strongly dependent on the velocity of the flowing blood, with 10 cm/s yielding the largest loss in efficiency due to magnetization transfer effects. Flowing blood phantom experiments confirmed faster relaxation of the inversion label than that predicted by T(1) decay alone.

Optimized clinical T2 relaxometry with a standard CPMG sequence.

PURPOSE: To optimize the accuracy and precision of T2 measurements using the standard Carr-Purcell-Meiboom-Gill (CPMG) sequence. T2 values obtained with this technique are normally sensitive to imperfect refocusing due to the formation of unwanted stimulated echoes. MATERIALS AND METHODS: Modifications are made to the refocusing slice selection width and the interleaving scheme. A widened refocusing slice improves the uniformity of the refocusing flip angle across the slice. A slow spin echo acquisition provided "gold standard" T2 values. Repeated T2 measurements in phantom and human studies are used to compare the accuracy and precision of the optimized and non-optimized CPMG implementations. RESULTS: The required slice thickness ratio between refocusing and excitation slice widths is found to be 3:1 for typical optimized radiofrequency pulses. T2 values obtained using this optimized implementation more closely correspond to "gold standard" values. Repeated T2 measurements indicate significantly improved correspondence between data and model. A reduction in the fitting error of approximately 70% is demonstrated for phantoms. CONCLUSION: We demonstrate that a relatively simple change to the CPMG relaxometry sequence parameters from the default setup yields significant improvements in the accuracy and precision of T2 measurements.

TurboFLASH FAIR imaging with optimized inversion and imaging profiles.

Optimal implementation of pulsed arterial spin labeling (PASL) methods such as flow-sensitive alternating inversion recovery (FAIR), require the minimization of interactions between the inversion and imaging slabs. For FAIR, the inversion:imaging slice thickness ratio (STR) is usually at least 3:1 in order to fully contain the extent of the imaging slice. The resulting gap exacerbates the transit time. So far, efforts to minimize the STR have concentrated on the inversion profile. However, the imaging profile remains a limiting factor especially for rapid sequences such as turbo fast low-angle shot (TurboFLASH) which uses short pulses. This study reports the implementation of a TurboFLASH sequence with optimized inversion and imaging profiles. Slice-selection is achieved with a preparation module incorporating a pair of identical adiabatic frequency offset corrected inversion (FOCI) pulses. The optimum radiofrequency (RF) and gradient scheme for this pulse combination is described, and the relaxation characteristics of the slice-selection scheme are investigated. Phantom experiments demonstrate a reduction in the STR to approximately 1.13:1. Implementation in an animal model is described, and the benefit of the improved profile in probing the sensitivity of the flow signal to tagging geometry is demonstrated. Sensitivity to transit time effects can be minimized with this sequence, and ASL methodologies can be better explored as a result of the improved conformance with the ideal of square slice profiles.

Pulsed arterial spin labeling using TurboFLASH with suppression of intravascular signal.

Accurate quantification of perfusion with the ADC techniques requires the suppression of the majority of the intravascular signal. This is normally achieved with the use of diffusion gradients. The TurboFLASH sequence with its ultrashort repetition times is not readily amenable to this scheme. This report demonstrates the implementation of a modified TurboFLASH sequence for FAIR imaging. Intravascular suppression is achieved with a modified preparation period that includes a driven equilibrium Fourier transform (DEFT) combination of 90 degrees-180 degrees-90 degrees hard RF pulses subsequent to the inversion delay. These pulses rotate the perfusion-prepared magnetization into the transverse plane where it can experience the suitably placed diffusion gradients before being returned to the longitudinal direction by the second 90 degrees pulse. A value of b = 20-30 s/mm(2) was thereby found to suppress the majority of the intravascular signal. For single-slice perfusion imaging, quantification is only slightly modified. The technique can be readily extended to multislice acquisition if the evolving flow signal after the DEFT preparation is considered. An advantage of the modified preparation scheme is evident in the multislice FAIR images by the preservation of the sign of the magnetization difference.