The surgical treatment of Balanitis Xerotica Obliterans

Background: Balanitis Xerotica Obliterans (BXO) is a chronic, often progressive disease, which can lead to phimosis and urethral stenosis, affecting both urinary and sexual function. Steroid creams are usually the first-line treatment but have a limited role and surgical intervention is frequently necessary. Conservative surgical procedures (circumcision) are often preferred in the first instance with the premise that recurrence of disease will require a more definitive reconstruction. This study looked at patients with pathologically proven BXO referred to the Plastic Surgery Unit at James Cook University Hospital between 2005 and 2009. The aim was to look at their management in the past and subsequent management by us. We also looked at whether early referral of progressive and recurrent BXO patients to reconstructive surgery could have prevented unnecessary delay in resolving symptoms at an earlier stage. Materials and Methods: Data was collected retrospectively and information regarding the exact anatomical location affected, the extent of the disease, the referring specialty and any previous surgical interventions was obtained. Alterations in urinary and sexual function and relief of symptoms following reconstructive surgery were analysed. Results: Of the 23 patients in the study, 43% had previous surgery and 60% of those had undergone two or more procedures. Twenty-one percent of patients had a history of BXO for over five years. Forty-seven percent of patients had alteration in their urinary function and 48% alteration in their sexual function due to the disease, prior to referral. Early results showed remarkable improvement in urinary and sexual function following reconstructive surgery in this group. Conclusions: Steroid creams have been shown to limit the progression of the disease but do not offer a cure in the majority of cases. Circumcision can be a curative procedure in early disease. Although there is conflicting evidence for treatment of recurring urethral strictures, repeated urethrotomy or urethral dilatation has poor long-term outcome. In patients with recurrent disease and associated complications we propose early referral to a plastic surgeon with genitourinary interest or reconstructive urologist for definitive treatment.

Hyperpolarized relaxometry based nuclear T1 noise spectroscopy in diamond

The origins of spin lifetimes in quantum systems is a matter of importance in several areas of quantum information. Spectrally mapping spin relaxation processes provides insight into their origin and motivates methods to mitigate them. In this paper, we map nuclear relaxation in a prototypical system of [Formula: see text] nuclei in diamond coupled to Nitrogen Vacancy (NV) centers over a wide field range (1 mT-7 T). Nuclear hyperpolarization through optically pumped NV electrons allows signal measurement savings exceeding million-fold over conventional methods. Through a systematic study with varying substitutional electron (P1 center) and [Formula: see text] concentrations, we identify the operational relaxation channels for the nuclei at different fields as well as the dominant role played by [Formula: see text] coupling to the interacting P1 electronic spin bath. These results motivate quantum control techniques for dissipation engineering to boost spin lifetimes in diamond, with applications including engineered quantum memories and hyperpolarized [Formula: see text] imaging.

Crystal structure of 4,5,6,7,8,8-hexa-chloro-2-(3,4-di-meth-oxy-pheneth-yl)-3a,4,7,7a-tetra-hydro-1H-4,7-methano-iso-indole-1,3(2H)-dione [+solvent]

In the title compound, C19H15Cl6NO4 [+solvent], the six-membered ring of the norbornene moiety adopts a boat conformation and the two five-membered rings have envelope conformations. The pyrrolidine ring makes a dihedral angle of 14.83 (12)° with the 3,4-di-meth-oxy-phenyl ring, which are attached to each other by an extended N-CH2-CH2-Car bridge. In the crystal, the structure features C-H⋯O inter-molecular hydrogen bonds, an offset π-π inter-action [inter-centroid distance = 3.564 (1) Å] and a C-Cl⋯π inter-action. The contribution of some disordered solvent to the scattering was removed using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] of PLATON. The solvent contribution was not included in the reported mol-ecular weight and density.

The Geographic Impact on Hospitalization in Patients with Cystic Fibrosis

OBJECTIVE

To assess whether geographic location influences hospitalizations for pulmonary exacerbations for patients with cystic fibrosis (CF) in the US, as there is no existing literature regarding this subject.

STUDY DESIGN

The CF Foundation Patient Registry was analyzed during the years 2007-2012 via geographic grouping of states. The impact of geographic region on recovery from hospitalization, hospitalization length, and time to next hospitalization were analyzed using multivariate models.

RESULTS

Posthospitalization lung function and nutritional measures were similar among regions for 1 year following hospitalization. The West region was associated with risk of longer hospital stays (OR 1.60, CI 1.45-1.77), however, dornase alfa use (OR 3.85, CI 1.15-12.92) was the only specific factor. History of allergic bronchopulmonary aspergillosis (OR 1.58, CI 1.11-2.25) and adult age (OR 2.48, CI 1.17-5.25) in the Northeast, chronic macrolide use in the South (OR 1.36, CI 1.03-1.79), and infection with Candida albicans (OR 1.47, CI 1.18-1.82) and Pseudomonas aeruginosa (OR 1.44, CI 1.02-2.04) in the Midwest were associated with increased hospitalization length. There was a significantly decreased risk for subsequent hospitalizations in the Northeast compared with other regions (P = .038). Sociodemographic analysis identified Caucasians in the South having a significantly lower risk of future hospitalization compared with African Americans (hazard ratio 0.79, CI 0.69-0.91, P = .0009).

CONCLUSIONS

There is significant regional variability in hospitalization length and risks for subsequent hospitalizations for patients with CF in the US. Regional variation should be subject to further study to determine if benchmarking standards can be achieved nationally.

Geographic variations in cystic fibrosis: An analysis of the U.S. CF Foundation Registry

BACKGROUND

Emerging evidence suggests that the prevalence of pathogens common in cystic fibrosis (CF) may be unevenly distributed across the United States (U.S.). However, very little is known regarding the U.S. distribution of other CF modifiers such as medication usage and patient demographics. Therefore, we sought to determine if regional differences exist in the distribution of demographic variables and patient disease characteristics in the U.S. that may play a role in differential CF outcomes.

METHODS

Data were analyzed from the 30,896 subjects in the U.S. CF Foundation Patient Registry during the years 2007-2012, via geographical grouping of states based upon the Nationwide Inpatient Sample classification.

RESULTS

Significant differences in racial distribution were seen, including half of the total U.S. African-American CF population residing in the South. Both African-Americans and Hispanics had increased Medicaid usage (52.2%, 41.8%, respectively). Culture-reported pathogens were markedly different across the U.S., with the highest percentage of patients with Methicillin-resistant Staphylococcus aureus (41.9%), Pseudomonas aeruginosa (71.2%), and non-tuberculous mycobacterium (10.0%) in the South. The South region also had the lowest mean body mass index and forced expiratory volume in one second. Chronic medication usage such as inhaled tobramycin or macrolides followed P. aeruginosa distribution, while inhaled dornase alfa was most used in the West (84.7%). Co-morbid conditions varied, with the highest percentage of depressed subjects in the Midwest (18.3%). Mean regional mortality rates were not statistically different among regions, although highest in each age grouping of the South.

CONCLUSIONS

The U.S. has significant regional variations in CF demographics, insurance, pathogens, medication usage, and co-morbidities, without an overall impact on regional mortality. Regional variations in care practices should be studied further based on the findings.

Plastic oscillators and fixed rhythms: changes in the phase of clock-gene rhythms in the PVN are not reflected in the phase of the melatonin rhythm of grass rats

The same clock-genes, including Period (PER) 1 and 2, that show rhythmic expression in the suprachiasmatic nucleus (SCN) are also rhythmically expressed in other brain regions that serve as extra-SCN oscillators. Outside the hypothalamus, the phase of these extra-SCN oscillators appears to be reversed when diurnal and nocturnal mammals are compared. Based on mRNA data, PER1 protein is expected to peak in the late night in the paraventricular nucleus of the hypothalamus (PVN) of nocturnal laboratory rats, but comparable data are not available for a diurnal species. Here we use the diurnal grass rat (Arvicanthis niloticus) to describe rhythms of PER1 and 2 proteins in the PVN of animals that either show the species-typical day-active (DA) profile, or that adopt a night-active (NA) profile when given access to running wheels. For DA animals housed with or without wheels, significant rhythms of PER1 or PER2 protein expression featured peaks in the late morning; NA animals showed patterns similar to those expected from nocturnal laboratory rats. Since the PVN is part of the circuit that controls pineal rhythms, we also measured circulating levels of melatonin during the day and night in DA animals with and without wheels and in NA wheel runners. All three groups showed elevated levels of melatonin at night, with higher levels during both the day and night being associated with the levels of activity displayed by each group. The differential phase of rhythms in the clock-gene protein in the PVN of diurnal and nocturnal animals presents a possible mechanism for explaining species differences in the phase of autonomic rhythms controlled, in part, by the PVN. The present study suggests that the phase of the oscillator of the PVN does not determine that of the melatonin rhythm in diurnal and nocturnal species or in diurnal and nocturnal chronotypes within a species.

Inductive measurement of optically hyperpolarized phosphorous donor nuclei in an isotopically enriched silicon-28 crystal

We experimentally demonstrate the first inductive readout of optically hyperpolarized phosphorus-31 donor nuclear spins in an isotopically enriched silicon-28 crystal. The concentration of phosphorus donors in the crystal was 1.5×10(15)  cm(-3), 3 orders of magnitude lower than has previously been detected via direct inductive detection. The signal-to-noise ratio measured in a single free induction decay from a 1  cm(3) sample (≈10(15) spins) was 113. By transferring the sample to an X-band ESR spectrometer, we were able to obtain a lower bound for the nuclear spin polarization at 1.7 K of ∼64%. The (31)P-T2 measured with a Hahn echo sequence was 420 ms at 1.7 K, which was extended to 1.2 s with a Carr Purcell cycle. The T1 of the (31)P nuclear spins at 1.7 K is extremely long and could not be determined, as no decay was observed even on a time scale of 4.5 h. Optical excitation was performed with a 1047 nm laser, which provided above-band-gap excitation of the silicon. The buildup of the hyperpolarization at 4.2 K followed a single exponential with a characteristic time of 577 s, while the buildup at 1.7 K showed biexponential behavior with characteristic time constants of 578 and 5670 s.

The BMPR2 missense mutation p.K230N and pulmonary arterial hypertension

We present a patient that is the index case of pulmonary arterial hypertension (PAH) in a child due to the bone morphogenetic protein type II (BMPR2) missense mutation p.K230N, also known as c.690A>T. Missense mutations typically have earlier onset and more severe disease in PAH, so pulmonologists should be aware of this in the evaluation of PAH in children.

Responses of brain and behavior to changing day-length in the diurnal grass rat (Arvicanthis niloticus)

Seasonal affective disorder (SAD) is a major depressive disorder that recurs in the fall and winter when day-length gets short. It is well accepted that day-length is encoded by the principal circadian clock located in the suprachiasmatic nucleus (SCN), but very little is known about day-length encoding in diurnal mammals. The present study utilized the grass rat, Arvicanthis niloticus, to investigate how the circadian system responds to photoperiodic changes in a diurnal mammal that shows day-length-dependent mood changes. The animals were initially housed in equatorial day-length (12h, EP) followed by either long (16h, LP) or short (8h, SP) photoperiods. The LP animals showed an expansion of the peak phase of the PER1 and PER2 rhythm in the SCN as well as an extended behavioral active phase. In contrast, the SP animals did not show any compression of their active phase nor a change in the peak duration of PER1 or PER2 expression, compared to those in EP. The results suggest that the circadian system in the diurnal grass rats is less responsive when day-length gets short compared to when it gets longer. The depression-like behaviors were assessed using sweet solution preference (SSP) and forced swimming test (FST). Animals in the SP group showed decreased SSP and increased immobility time in FST as compared to the EP group, suggesting a depressive phenotype. The present study serves as the first step toward exploring the role that the circadian system plays in SAD using a diurnal rodent model.

The surgical treatment of Balanitis Xerotica Obliterans

BACKGROUND

Balanitis Xerotica Obliterans (BXO) is a chronic, often progressive disease, which can lead to phimosis and urethral stenosis, affecting both urinary and sexual function. Steroid creams are usually the first-line treatment but have a limited role and surgical intervention is frequently necessary. Conservative surgical procedures (circumcision) are often preferred in the first instance with the premise that recurrence of disease will require a more definitive reconstruction. This study looked at patients with pathologically proven BXO referred to the Plastic Surgery Unit at James Cook University Hospital between 2005 and 2009. The aim was to look at their management in the past and subsequent management by us. We also looked at whether early referral of progressive and recurrent BXO patients to reconstructive surgery could have prevented unnecessary delay in resolving symptoms at an earlier stage.

MATERIALS AND METHODS

Data was collected retrospectively and information regarding the exact anatomical location affected, the extent of the disease, the referring specialty and any previous surgical interventions was obtained. Alterations in urinary and sexual function and relief of symptoms following reconstructive surgery were analysed.

RESULTS

Of the 23 patients in the study, 43% had previous surgery and 60% of those had undergone two or more procedures. Twenty-one percent of patients had a history of BXO for over five years. Forty-seven percent of patients had alteration in their urinary function and 48% alteration in their sexual function due to the disease, prior to referral. Early results showed remarkable improvement in urinary and sexual function following reconstructive surgery in this group.

CONCLUSIONS

Steroid creams have been shown to limit the progression of the disease but do not offer a cure in the majority of cases. Circumcision can be a curative procedure in early disease. Although there is conflicting evidence for treatment of recurring urethral strictures, repeated urethrotomy or urethral dilatation has poor long-term outcome. In patients with recurrent disease and associated complications we propose early referral to a plastic surgeon with genitourinary interest or reconstructive urologist for definitive treatment.

Daily rhythms and sex differences in vasoactive intestinal polypeptide, VIPR2 receptor and arginine vasopressin mRNA in the suprachiasmatic nucleus of a diurnal rodent, Arvicanthis niloticus

Diurnal and nocturnal animals differ with respect to the time of day at which the ovulatory surge in luteinizing hormone occurs. In some species this is regulated by the suprachiasmatic nucleus (SCN), the primary circadian clock, via cells that contain vasoactive intestinal polypeptide (VIP) and vasopressin (AVP). Here, we evaluated the hypothesis that chronotype differences in the timing of the luteinizing hormone surge are associated with rhythms in expression of the genes that encode these neuropeptides. Diurnal grass rats (Arvicanthis niloticus) were housed in a 12/12-h light-dark cycle and killed at one of six times of day (Zeitgeber time 1, 5, 9, 13, 17, 21; ZT 0 = lights-on). In-situ hybridization was used to compare levels of vip, avp and VIP receptor mRNA (vipr2) in the SCN of intact females, ovariectomized females, ovariectomized females given estradiol and intact males. We found a sex difference in vip rhythms with a peak occurring at ZT 13 in males and ZT 5 in intact females. In all groups avp mRNA rhythms peaked during the day, from ZT 5 to ZT 9, and had a trough in the dark at ZT 21. There was a modest rhythm and sex difference in the pattern of vipr2. Most importantly, the patterns of each of these SCN rhythms relative to the light-dark cycle resembled those seen in nocturnal rodents. Chronotype differences in timing of neuroendocrine events associated with ovulation are thus likely to be generated downstream of the SCN.

Compartmentalized expression of light-induced clock genes in the suprachiasmatic nucleus of the diurnal grass rat (Arvicanthis niloticus)

Photic responses of the circadian system are mediated through light-induced clock gene expression in the suprachiasmatic nucleus (SCN). In nocturnal rodents, depending on the timing of light exposure, Per1 and Per2 gene expression shows distinct compartmentalized patterns that correspond to the behavioral responses. Whether the gene- and region-specific induction patterns are unique to nocturnal animals, or are also present in diurnal species is unknown. We explored this question by examining the light-induced Per1 and Per2 gene expression in functionally distinct SCN subregions, using diurnal grass rats Arvicanthis niloticus. Light exposure during nighttime induced Per1 and Per2 expression in the SCN, showing unique spatiotemporal profiles depending on the phase of the light exposure. After a phase delaying light pulse (LP) in the early night, strong Per1 induction was observed in the retinorecipient core region of the SCN, while strong Per2 induction was observed throughout the entire SCN. After a phase advancing LP in the late night, Per1 was first induced in the core and then extended into the whole SCN, accompanied by a weak Per2 induction. This compartmentalized expression pattern is very similar to that observed in nocturnal rodents, suggesting that the same molecular and intercellular pathways underlying acute photic responses are present in both diurnal and nocturnal species. However, after an LP in early subjective day, which induces phase advances in diurnal grass rats, but not in nocturnal rodents, we did not observe any Per1 or Per2 induction in the SCN. This result suggests that in spite of remarkable similarities in the SCN of diurnal and nocturnal rodents, unique mechanisms are involved in mediating the phase shifts of diurnal animals during the subjective day.

Daily rhythms in PER1 within and beyond the suprachiasmatic nucleus of female grass rats (Arvicanthis niloticus)

Although circadian rhythms of males and females are different in a variety of ways in many species, their mechanisms have been primarily studied in males. Furthermore, rhythms are dramatically different in diurnal and nocturnal animals but have been studied predominantly in nocturnal ones. In the present study, we examined rhythms in one element of the circadian oscillator, the PER1 protein, in a variety of cell populations in brains of diurnal female grass rats. Every 4 h five adult female grass rats kept on a 12-h light/dark (LD) cycle were perfused and their brains were processed for immunohistochemical detection of PER1. Numbers of PER1-labeled cells were rhythmic not only within the suprachiasmatic nucleus (SCN), the locus of the primary circadian clock in mammals, but also in the peri-suprachiasmatic region, the oval nucleus of the bed nucleus of the stria terminalis, the central amygdala, and the nucleus accumbens. In addition, rhythms were detected within populations of neuroendocrine cells that contain tyrosine hydroxylase. The phase of the rhythm within the SCN was advanced compared with that seen previously in male grass rats. Rhythms beyond the SCN were varied and different from those seen in most nocturnal species, suggesting that signals originating in the SCN are modified by its direct and/or indirect targets in different ways in nocturnal and diurnal species.

Dynamic nuclear polarization in silicon microparticles

We report record high 29Si spin polarization obtained using dynamic nuclear polarization in microcrystalline silicon powder. Unpaired electrons in this silicon powder are due to dangling bonds in the amorphous region of this intrinsically heterogeneous sample. 29Si nuclei in the amorphous region become polarized by forced electron-nuclear spin flips driven by off-resonant microwave radiation while nuclei in the crystalline region are polarized by spin diffusion across crystalline boundaries. Hyperpolarized silicon microparticles have long T1 relaxation times and could be used as tracers for magnetic resonance imaging.

Simulations of information transport in spin chains

Transport of quantum information in linear spin chains has been the subject of much theoretical work. Experimental studies by NMR in solid state spin systems (a natural implementation of such models) is complicated since the dipolar Hamiltonian is not solely comprised of nearest-neighbor XY-Heisenberg couplings. We present here a similarity transformation between the XY Hamiltonian and the double-quantum Hamiltonian, an interaction which is achievable with the collective control provided by radio-frequency pulses. Not only can this second Hamiltonian simulate the information transport in a spin chain, but it also creates coherent states, whose intensities give an experimental signature of the transport. This scheme makes it possible to study experimentally the transport of polarization beyond exactly solvable models and explore the appearance of quantum coherence and interference effects.

A technique for introducing looped sutures in flexor tendon repair

This is the author′s experience of hypospadias reconstruction using Bracka′s technique (mainly) over a period of three years. A total of 98 procedures related to hypospadias were done in three years. The surgical technique is described. In the author′s hand, Bracka′s technique gives good result both functionally and in appearance. Its versatility enables its use in all types of hypospadias with consistently reproducible results with minimal complications. At the end of the second stage a circumcised penis with natural looking vertical slit neo-meatus at the apex of the glans is produced.

The reclusive patient-a case report & clinical review of Merkel cell carcinoma

Advanced Merkel Cell Carcinoma with intra - hepatic metastases in a reclusive gentleman is described. We present an interesting case with learning points and a review of this uncommon malignancy.

Entanglement assisted metrology

We propose a new approach to the measurement of a single spin state, based on nuclear magnetic resonance (NMR) techniques and inspired by the coherent control over many-body systems envisaged by quantum information processing. A single target spin is coupled via the magnetic dipolar interaction to a large ensemble of spins. Applying radio frequency pulses, we can control the evolution so that the spin ensemble reaches one of two orthogonal states whose collective properties differ depending on the state of the target spin and are easily measured. We first describe this measurement process using quantum gates; then we show how equivalent schemes can be defined in terms of the Hamiltonian and thus implemented under conditions of real control, using well established NMR techniques. We demonstrate this method with a proof of principle experiment in ensemble liquid state NMR and simulations for small spin systems.

Spin diffusion of correlated two-spin states in a dielectric crystal

Reciprocal space measurements of spin diffusion in a single crystal of calcium fluoride (CaF2) have been extended to dipolar ordered states. The experimental results for the component of the spin diffusion rate parallel to the external field are D(parallel)(D)=29+/-3x10(-12) cm(2)/s for the [001] direction and D(parallel)(D)=33+/-4x10(-12) cm(2)/s for the [111] direction. The measured diffusion rates for dipolar order are faster than those for Zeeman order and are considerably faster than predicted by simple theoretical models. It is suggested that constructive interference in the transport of the two-spin states is responsible for this enhancement. As expected, the anisotropy in the diffusion rates is observed to be significantly less for dipolar order compared to the Zeeman case.

Pulse error compensating symmetric magic-echo trains

We present improved line-narrowing sequences for dipolar coupled spin systems, based on a train of magic-echoes which are compensated for the effects of finite pulse widths and utilize symmetry properties of supercycles. Sequences are introduced for spectroscopy and imaging by proper choice of a phase alternating scheme. Using a 16 pulse time-suspension magic-echo cycle, the highest level of line-narrowing achieved was 2.7 Hz for the [100] direction of a single crystal of calcium fluoride, a reduction in linewidth by 4 orders of magnitude.

Mapping the absolute value of M0 using dipolar field effects

The ability to map the spatial variation of the absolute, rather than the relative value of the equilibrium magnetization could be advantageous in many areas of NMR. However, direct measurement of M(0) is usually difficult because of the multiparametric dependence of the NMR signal. Here we propose a technique for mapping the spatial variation of the absolute value of M(0), independent of relaxation weighting and flip angle calibration. This method, which works best at high field strengths, is based on the effect of the dipolar field due to the nuclear magnetization that is normally neglected in liquid-state NMR. The experimental implementation of this sequence at 3.0 T is described, and its initial application to the measurement of the water content of brain tissue is outlined.

Fat emulsification measured using NMR transverse relaxation

This paper presents a novel method of measuring the droplet size in oil-in-water emulsions. It is based on changes in the NMR transverse relaxation rate due to the effect of microscopic magnetic susceptibility differences between fat droplets and the surrounding water. The longitudinal and transverse relaxation rates of a series of emulsions with constant oil volume fraction and five different mean droplet sizes, in the range 0.4-20.9 microm, were measured in vitro at 37 degrees C using EPI. While the longitudinal relaxation rate 1/T(1) did not change significantly, 1/T(2) was observed to increase with mean droplet size. The measured changes in 1/T(2) were found to be in good agreement with results predicted from proton random walk simulations, and were also consistent with analytical solutions based on an outer sphere relaxation model. Measurements of 1/T(2) on emulsions with a higher oil volume fraction, and on emulsions of a fixed size where the water phase was doped with gadolinium to modulate the susceptibility difference between the phases, also showed the predicted behavior. As part of this study the susceptibility difference between olive oil and water was measured to be 1.55 ppm.

Method for measuring local hydraulic permeability using magnetic resonance imaging

The hydraulic permeability of a porous medium characterizes the ease with which a fluid may be driven through it, and is defined via the classical Darcy law. A method for noninvasive, nondestructive measurement of one projection of the local permeability tensor of a porous medium, using gas phase magnetic resonance imaging, is presented. Results are shown for one-dimensional experiments on dry porous rocks. The limitations of the method are explored, and the extension to three-dimensional imaging of the permeability is discussed.

Imaging the long-range dipolar field in structured liquid state samples

We describe imaging experiments in which the pattern of the dipolar field generated by spatially modulated nuclear magnetization is directly visualized in simply structured phantoms. Two types of experiment have been carried out at 11.7 T using (1)H NMR signals. In the first, the field from a single spin species is imaged via its own NMR signal. In the second, the NMR signal from one spin species is used to image the field generated by a second species. The field patterns measured in these experiments correspond well with those calculated using simple theoretical expressions for the dipolar field. The results also directly demonstrate the spatial sensitivity of the signal generated using dipolar field effects, indicating that the range of the field depends upon the inverse of the spatial frequency with which the magnetization is modulated.

Measuring spatially resolved gas transport and adsorption in coal using MRI

The storage and transport of gases in coal is of tremendous importance in the utilisation of coalbeds, and in particular the recovery of methane. There is also increasing interest in the use of coal mines as sites for carbon dioxide sequestration to alleviate the potentially harmful effects of global warming. This paper demonstrates the use of magnetic resonance imaging to investigate the spatiotemporal dynamics of gas transport in coal. The presence of significant structural heterogeneities in the coal was observed. Dynamical effects displayed a broad range of time constants ranging from minutes to days.

Direct measurement of porous media local hydrodynamical permeability using gas MRI

The concept of hydraulic permeability is at the core of modeling single phase or multi-phase flow in heterogeneous porous media, as it is the spatial distribution of the permeability that primarily governs the behavior of fluid flow in the medium. To date, the modeling of fluid flow in porous media has been hampered by poor estimates of local permeability. Magnetic Resonance Imaging is well known for its ability to measure non-invasively the local density and flow rate of different fluids saturating porous media [1,2]. In this paper we demonstrate the first non-invasive method for the direct measurement of a single projection of the local permeability tensor of a porous medium using gas-phase MRI. The potential for three-dimensional imaging of the medium permeability is also discussed. The limitations of the method are listed and results are presented in a model porous medium as well as in a real oil reservoir rock.

Electrocardiographic imaging: I. Effect of torso inhomogeneities on body surface electrocardiographic potentials

INTRODUCTION

Body surface potential maps (BSPMs) and conventional ECG reflect electrical sources generated by cardiac excitation and repolarization and noninvasively provide important diagnostic information about the electrical state of the heart. Because the heart is located within the torso volume conductor, body surface potentials also reflect the effects of torso inhomogeneities, which include blood, lungs, bone, muscle, fat, and fluid. It is necessary to characterize and understand these effects in order to interpret BSPM and ECG in terms of cardiac activity without "contamination" from the inhomogeneous volume conductor.

METHODS AND RESULTS

Actual measured epicardial and body surface potentials were obtained during normal sinus rhythm and for different pacing protocols from a Langendorff-perfused dog heart suspended in a human-shaped torso tank. Accurate geometry of the torso inhomogeneities was digitized from the Visual Human Project and appropriately introduced into a computer model of the tank setup. The geometry and electrical properties of the volume conductor could be varied. Both homogeneous and inhomogeneous torsos have major smoothing effects on BSPM, which is of very low resolution compared with its corresponding epicardial potential pattern. Relative to a homogeneous torso, the inhomogeneities have only a minor effect on BSPM patterns. They augment potential magnitudes depending on the pattern of epicardial activation. Variations of geometry and electrical properties within the normal physiologic range have minimal effects.

CONCLUSION

Effects of torso inhomogeneities on 12-lead ECGs are minimal, and the associated ECG changes fall within the range of normal interindividual variations.

Electrocardiographic imaging: II. Effect of torso inhomogeneities on noninvasive reconstruction of epicardial potentials, electrograms, and isochrones

INTRODUCTION

Noninvasive electrocardiographic imaging (ECGI) involves inverse reconstruction of epicardial potentials, electrograms (EGMs), and isochrones from body surface potential maps (BSPMs). The heart lies in a volume conductor that includes lungs, blood, bone, muscle, and fluid. We investigate the effects of these torso inhomogeneities on reconstructed epicardial potentials, EGMs, and isochrones to address the issue of whether they should be included in clinical ECGI methodology.

METHODS AND RESULTS

Potential data were obtained for different pacing protocols from a dog heart suspended in a human-shaped torso tank. Accurate geometry of torso inhomogeneities was digitized from the Visual Human Project and appropriately introduced into a computer model of the torso. Three models were used: accurate inhomogeneous torso, homogeneous torso, and a torso with stylized lungs (to generate an approximate model). The inhomogeneous model was used to compute BSPMs from the measured epicardial potentials. These BSPMs were the starting point for inverse computations in the different torso models. Epicardial potential maps, EGMs, and isochrones were computed. The homogeneous model produced slightly less accurate epicardial potential reconstructions than the inhomogeneous model and stylized lung model, but epicardial potential patterns, EGMs, isochrones, and locations of pacing sites were reconstructed with comparable accuracy when torso inhomogeneities were ignored.

CONCLUSION

The results demonstrate that, in the clinical application, it is not necessary to include torso inhomogeneities for noninvasive reconstructions of epicardial potentials, EGMs, and activation sequences.

Quantitative solid-state NMR imaging of synthetic calcium phosphate implants

It is shown that solid-state phosphorus-31 nuclear magnetic resonance imaging can be used to measure quantitatively the mass of hydroxyapatite (HA), a synthetic calcium phosphate used as an orthopedic implant material, in the presence of bone. A three-dimensional projection reconstruction technique was used to produce solid-state images from 998 free induction decays sampled in the presence of a fixed amplitude field gradient whose direction was varied uniformly over the unit sphere. Chemical selection is achieved using T1 contrast, as the synthetic calcium phosphate has a shorter T1 (1.8 sec at 4.7 T) compared with the bone (approximately 15 sec at 4.7 T in vivo, 42 sec ex vivo). Experimental results demonstrating the linear relationship between image intensity and HA density in phantoms containing HA and silicon (IV) oxide, and HA and bone are shown. Chemically pure images of bone mineral and synthetic HA have been computed from images of New Zealand White rabbits acquired in vivo at two different recycle times. The technique can be used to follow noninvasively the resorption and remodeling of calcium phosphate implants in vivo.

ADRF differential cross polarization spectroscopy of synthetic calcium phosphates and bone mineral

An adiabatic demagnetization in the rotating frame (ADRF) differential cross polarization (DCP), or inversion recovery cross polarization (IRCP), technique has been developed to study synthetic calcium phosphates and bone mineral. ADRF of the protons followed by a remagnetization of the phosphorus-31 spins results in an equalization of the dipolar and phosphorus Zeeman nuclear spin temperatures. By shifting the phase of the phosphorus RF by 180 degrees during the forward cross polarization it is possible to invert the temperature of this reservoir and initiate reverse cross polarization. Transient Strombotne-Hahn oscillations were observed on inverting the temperature. The presence of these oscillations complicates the determination of a null point on the basis of cross polarization times. It is necessary to shift the phase of the RF only after a Zeeman spin temperature can be defined, and to use an RF field strength that is slightly smaller than the equivalent S-spin local dipolar field in order to produce a zero crossing after the transient oscillations have decayed.

Scald burns in children caused by hot drinks--the importance of the type of cup

A prospective study of 36 consecutive scald injuries in children caused by hot beverages is reported. Almost a third of these were deep dermal or full skin thickness and the highest percentage resulted in injury to the upper chest region. The study further investigates the cooling characteristics in four different types of cup. These studies clearly show the potential for significant disfigurement from this type of injury for up to 11 min from the time the drink is poured. The need for greater public awareness in relation to hot drinks is highlighted.