A computational model of ureteral peristalsis and an investigation into ureteral reflux.

The aim of this study is to create a computational model of the human ureteral system that accurately replicates the peristaltic movement of the ureter for a variety of physiological and pathological functions. The objectives of this research are met using our in-house fluid-structural dynamics code (CgLes-Y code). A realistic peristaltic motion of the ureter is modelled using a novel piecewise linear force model. The urodynamic responses are investigated under two conditions of a healthy and a depressed contraction force. A ureteral pressure during the contraction shows a very good agreement with corresponding clinical data. The results also show a dependency of the wall shear stresses on the contraction velocity and it confirms the presence of a high shear stress at the proximal part of the ureter. Additionally, it is shown that an inefficient lumen contraction can increase the possibility of a continuous reflux during the propagation of peristalsis.

Developing nursing research in the United Arab Emirates: a narrative review.

AIM: This article identified, critically analysed and synthesized the literature on international nursing and midwifery research capacity building and standards. BACKGROUND: The United Arab Emirates is heavily dependent up on expatriate nurses. Only 4% of nurses working within the country are Emirati. The nation is therefore committed to developing nurses and nursing as a profession. INTRODUCTION: The United Arab Emirates' Nursing and Midwifery Council was formed in 2009 and initially focused on regulation, education and specialization. This review was undertaken to inform the work of the Council's newly established Scientific Research Sub-Committee. METHODS: A rapid narrative review was conducted using the Cumulative Index of Nursing and Allied Health Literature database, key words, Boolean operators, parameters and a journal-specific search. An inclusion/exclusion criterion was identified. RESULTS: The search provided 332 articles with 45 included in the final review. The literature on nursing research 'standards' and 'capacity building' is diverse and inconsistent across continents and in approaches. DISCUSSION: Nursing research has evolved to varying degrees across the globe. Nevertheless, irrespective of the locale, there are similar problems encountered in growing research, for example nursing faculty shortage, lack of collaborative research, funding. There are also specific challenges in the Middle East and North Africa region. LIMITATIONS: The review was constrained by time and access. CONCLUSION AND IMPLICATIONS FOR NURSING POLICY: There are specific challenges for the United Arab Emirates. However, the country is well placed to learn from the experiences of colleagues elsewhere. Time and commitment is required to build the solid foundations necessary to ensure robust, sustained growth. Identifying research capacity as both a process and outcome at the outset may also assist. Further, it may be prudent to consider initiating a Gulf Coast Countries' collaborative approach to building research capacity to harness scare resources and create a larger critical mass.

Spatial co-adaptation of cortical control columns in a micro-ECoG brain-computer interface.

OBJECTIVE: Electrocorticography (ECoG) has been used for a range of applications including electrophysiological mapping, epilepsy monitoring, and more recently as a recording modality for brain-computer interfaces (BCIs). Studies that examine ECoG electrodes designed and implanted chronically solely for BCI applications remain limited. The present study explored how two key factors influence chronic, closed-loop ECoG BCI: (i) the effect of inter-electrode distance on BCI performance and (ii) the differences in neural adaptation and performance when fixed versus adaptive BCI decoding weights are used. APPROACH: The amplitudes of epidural micro-ECoG signals between 75 and 105 Hz with 300 µm diameter electrodes were used for one-dimensional and two-dimensional BCI tasks. The effect of inter-electrode distance on BCI control was tested between 3 and 15 mm. Additionally, the performance and cortical modulation differences between constant, fixed decoding using a small subset of channels versus adaptive decoding weights using the entire array were explored. MAIN RESULTS: Successful BCI control was possible with two electrodes separated by 9 and 15 mm. Performance decreased and the signals became more correlated when the electrodes were only 3 mm apart. BCI performance in a 2D BCI task improved significantly when using adaptive decoding weights (80%-90%) compared to using constant, fixed weights (50%-60%). Additionally, modulation increased for channels previously unavailable for BCI control under the fixed decoding scheme upon switching to the adaptive, all-channel scheme. SIGNIFICANCE: Our results clearly show that neural activity under a BCI recording electrode (which we define as a 'cortical control column') readily adapts to generate an appropriate control signal. These results show that the practical minimal spatial resolution of these control columns with micro-ECoG BCI is likely on the order of 3 mm. Additionally, they show that the combination and interaction between neural adaptation and machine learning are critical to optimizing ECoG BCI performance.

The value of bioelectrical impedance analysis and phase angle in the evaluation of malnutrition and quality of life in cancer patients--a comprehensive review.

Bioelectrical impedance analysis (BIA) and especially its derived parameter phase angle have been widely used in different populations. The variability of BIA measures has often been cited as a major limitation for its clinical use in evaluating nutritional status and overall health of patients. Cancer patients often present with malnourishment and cachexia, which complicate the course of treatment and affect outcomes. PubMed, CINAHL, EBSCO and Cochrane Library have been searched for relevant publications in English for BIA in cancer patients. Out of 197 total results, 27 original research articles related to BIA measures in cancer patients were included in this review. Studies indicate that the use of BIA and phase angle measures can benefit in the clinical management of cancer patients in multiple ways: in the prevention; diagnosis; prognosis; and outcomes related to treatments that affect nutritional and overall health status. Phase angle and fat-free mass measures were most commonly evaluated and correlated with nutritional status and survival rate. One limitation of BIA measures is the high interpatient variability which requires careful interpretation of results in the context of the individual patient rather than comparison with population data. The BIA and phase angle provide practitioners for the evaluation of nutritional and overall health status in cancer patients with a convenient and non-invasive technique and should be encouraged.

Note: design and construction of a multi-scale, high-resolution, tube-generated x-ray computed-tomography system for three-dimensional (3D) imaging.

The design and construction of a high resolution modular x-ray computed tomography (XCT) system is described. The approach for meeting a specified set of performance goals tailored toward experimental versatility is highlighted. The instrument is unique in its detector and x-ray source configuration, both of which enable elevated optimization of spatial and temporal resolution. The process for component selection is provided. The selected components are specified, the custom component design discussed, and the integration of both into a fully functional XCT instrument is outlined. The novelty of this design is a new lab-scale detector and imaging optimization through x-ray source and detector modularity.

Performance of the new generation of whole-body PET/CT scanners: Discovery STE and Discovery VCT.

PURPOSE: The new GE Discovery STE and Discovery VCT respectively combine 16-slice and 64-slice CT with PET. The PET scanner has a new BGO detector block of 8 x 6 matrix (6.3 x 4.7 x 30 mm(3)). The aim of this study was to test the performance of the new scanner. METHODS: The PET performance evaluation was done using NEMA methodology. Owing to improved front-end electronics, the system was tested with different energy window and coincidence timing settings. RESULTS: Transaxial resolution FWHM for 2D(3D) mode at 1 cm offset from the centre of the field of view (R1) was 4.87 mm (5.12 mm) and at 10 cm off centre (R10) radially 5.70 mm (5.89 mm) and tangentially 5.84 mm (5.47 mm). The axial resolutions were 4.4 mm (5.18 mm) (R1) and 5.99 mm (5.86 mm) (R10). The sensitivities were 2.3 cps/kBq (8.8 cps/kBq) (R0, centre of field of view) and 2.3 cps/kBq (8.9 cps/kBq) (R10). The system scatter fraction was 21.4% in 2D at an energy of 375 keV (33.9% in 3D mode at a higher energy of 425 keV). Peak noise equivalent count rates (k=1) were 84.9 kcps at 43.9 kBq/ml (2D) and 67.6 kcps at 12.1 kBq/ml (3D). In image quality measurement the hot sphere to background contrast with 10- to 22-mm diameter spheres varied from 14% to 68%, being slightly better in 3D than in 2D mode. Cold sphere contrast was 67% in 2D and 59% in 3D mode. CONCLUSION: GE's new STE and VCT PET/CT systems have improved spatial resolution without loss in sensitivity. When compared with the LYSO crystal-based GE Discovery RX, the resolution and scatter fraction are comparable, the count rate capability is lower but the sensitivity is higher.

Spatial distribution of acaricide profiles (Boophilus microplus strains susceptible or resistant to acaricides) in southeastern Mexico.

The ability of Boophilus microplus strains to be susceptible (-) or resistant (+) to amidines (Am), synthetic pyrethroids (SP), and/or organo-phosphates (OP) (or acaricide profiles) was investigated in 217 southeastern Mexican cattle ranches (located in the states of Yucatán, Quintana Roo, and Tabasco). Three questions were asked: (1) whether acaricide profiles varied at random and, if not, which one(s) explained more (or less) cases than expected, (2) whether the spatial distribution of acaricide profiles was randomly or non-randomly distributed, and (3) whether acaricide profiles were associated with farm-related covariates (frequency of annual treatments, herd size, and farm size). Three acaricide profiles explained 73.6% of the data, representing at least twice as many cases as expected (P<0.001): (1) Am-SP-, (2) Am+SP+, and (3) (among ranches that dispensed acaricides > or = 6 times/year) Am-OP+SP+. Because ticks collected in Yucatán ranches tended to be susceptible to Am, those of Quintana Roo ranches displayed, predominantly, resistance to OP/SP, and Tabasco ticks tended to be resistant to Am (all with P < or = 0.05), acaricide profiles appeared to be non-randomly disseminated over space. Across states, two farm-related covariates were associated with resistance (P < or = 0.02): (1) high annual frequency of acaricide treatments, and (2) large farm size. Findings supported the hypothesis that spatial acaricide profiles followed neither random nor homogeneous data distributions, being partially explained by agent- and/or farm-specific factors. Some profiles could not be explained by these factors. Further spatially explicit studies (addressing host-related factors) are recommended.

An HMM-based speech-to-video synthesizer.

Emerging broadband communication systems promise a future of multimedia telephony, e.g. the addition of visual information to telephone conversations. It is useful to consider the problem of generating the critical information useful for speechreading, based on existing narrowband communications systems used for speech. This paper focuses on the problem of synthesizing visual articulatory movements given the acoustic speech signal. In this application, the acoustic speech signal is analyzed and the corresponding articulatory movements are synthesized for speechreading. This paper describes a hidden Markov model (HMM)-based visual speech synthesizer. The key elements in the application of HMMs to this problem are the decomposition of the overall modeling task into key stages and the judicious determination of the observation vector's components for each stage. The main contribution of this paper is a novel correlation HMM model that is able to integrate independently trained acoustic and visual HMMs for speech-to-visual synthesis. This model allows increased flexibility in choosing model topologies for the acoustic and visual HMMs. Moreover the propose model reduces the amount of training data compared to early integration modeling techniques. Results from objective experiments analysis show that the propose approach can reduce time alignment errors by 37.4% compared to conventional temporal scaling method. Furthermore, subjective results indicated that the purpose model can increase speech understanding.

The calcium-sensing receptor regulates calcium absorption in MDCK cells by inhibition of PMCA.

Calcium transport across a monolayer of Madin-Darby canine kidney (MDCK) cells was measured in response to stimulation of the basal surface with calcium-sensing receptor (CaR) agonists. Stimulation of the CaR resulted in a time- and concentration-dependent inhibition of calcium transport but did not change transepithelial voltage or resistance. Inhibition of transport was not altered by pretreatment of cells with pertussis toxin but was blocked by the phospholipase C (PLC) inhibitor U-73122. To determine a potential mechanism by which the CaR could inhibit calcium transport, we measured activity of the plasma membrane calcium ATPase (PMCA). Stimulation of the CaR on the basal surface resulted in an inhibition of the PMCA in a concentration- and PLC-dependent manner. Thus stimulation of the CaR inhibits both calcium transport and PMCA activity through a PLC-dependent pathway. These studies provide the first direct evidence that calcium can inhibit its own transcellular absorption in a model of the distal tubule. In addition, they provide a potential mechanism for the CaR to inhibit calcium transport, inhibition of PMCA.

Investigation of risk factors for porcine Taenia solium cysticercosis: a multiple regression analysis of a cross-sectional study in the Yucatan Peninsula, Mexico.

A cross-sectional survey for seropositivity to cysticercosis of pigs in the Yucatan Peninsula, Mexico, was carried out in 1996 together with a standardized questionnaire on predetermined individual pig and household risk factors for porcine infection. Serum samples from 697 pigs were analysed by immunoblot for antibodies to Taenia solium cysticercosis and questionnaires from 227 households in 18 villages were collected. All the data were analysed using multivariate analytical techniques taking household clustering into account. The overall porcine seroprevalence in the area was found to be 29%. The most important risk factors for seropositivity in pigs were presence versus absence of a toilet (adjusted odds ratio [adj. OR] 2.37, P = 0.005), crowded households (adj. OR 1.75, P = 0.034) and both corralling (adj. OR 2.14, P = 0.017) and letting pigs loose (adj. OR 2.32, P = 0.035) versus tying them up. There was evidence of clustering at household level and that possible risk factors at municipal or village level may also interact with higher risk management practices such as allowing pigs to run loose.

Performance characteristics of a whole-body PET scanner.

METHODS: This study characterizes the performance of a newly developed whole-body PET scanner (Advance, General Electric Medical Systems, Milwaukee, WI). The scanner consists of 12,096 bismuth germinate crystals (4.0 mm transaxial by 8.1 mm axial by 30 mm radial) in 18 rings, giving 35 two-dimensional image planes through an axial field of view of 15.2 cm. The rings are separated by retractable tungsten septa. Intrinsic spatial resolution, scatter fraction, sensitivity, high count rate performance and image quality are evaluated. RESULTS: Transaxial resolution (in FWHM) is 3.8 mm at the center and increases to 5.0 mm tangential and 7.3 mm radial at R = 20 cm. Average axial resolution decreases from 4.0 mm FWHM at the center to 6.6 mm at R = 20 cm. Scatter fraction is 9.4% and 10.2% for direct and cross slices, respectively. With septa out, the average scatter fraction is 34%. Total system sensitivity for true events (in kcps/(microCi/cc)) is 223 with septa in and 1200 with septa out. Dead-time losses of 50% correspond to a radioactivity concentration of 4.9 (0.81) microCi/cc and a true event count rate of 489 (480) kcps with septa in (out). Noise-equivalent count rate (NECR) for the system as a whole shows a maximum of 261 (159) kcps at a radioactivity concentration of 4.1 (0.65) microCi/cc with septa in (out). NECR is insensitive to changes in lower gamma-energy discrimination between 250-350 keV. CONCLUSIONS: The results show the performance of the newly designed PET scanner to be well suited for clinical and research applications.

Late knee problems in myelomeningocele.

This study was undertaken to assess the incidence and etiology of knee problems in a long-term follow-up of myelomeningocele patients. Of the 72 community ambulators reviewed, 17 (24%) had significant knee symptoms. A specific gait pattern was identified in symptomatic patients with low lumbar lesions, which may be explained on the basis of hip abductor and calf muscle weakness. These patients have a characteristic gait, which places abnormal stress on the knee, leading to medial and anteromedial rotary instability and eventual degenerative change. It is likely that disability resulting from knee symptoms will be the factor precluding independent ambulation in the patients reviewed in this study.

Evolution of femoral head deformity during the healing phase of Legg-Calvé-Perthes disease.

Progressive changes in the roundness of the femoral head were noted during the healing phase of hips with Legg-Calvé-Perthes disease. Forty-nine of 136 hips studied became progressively rounder, and 15 hips became progressively flatter after onset of reossification of the femoral head. The femoral head was more likely to undergo progressive flattening in older patients, in those with more severe lateral pillar involvement, and in those with prolonged reossification. These changes occurred during a 3- to 4-year reossification period after cessation of treatment.

The lateral pillar classification of Legg-Calvé-Perthes disease.

To determine the predictive value of a new classification system for Legg-Perthes, 93 hips in 86 patients with radiographic follow-up to maturity were reviewed. All patients were treated by bracing at the Texas Scottish Rite Hospital from 1970 to 1980. Hips were classified during the fragmentation stage of disease into three groups based on radiolucency in the lateral pillar of the femoral head. Final radiographs were reviewed at skeletal maturity, and the outcome was determined according to the Stulberg classification. Group A had a uniformly good outcome (100% Stulberg I and II results); Group B had a good outcome in patients who were less than 9 years at onset (92% Stulberg I and II, 8% Stulberg III results), but a less favorable outcome in patients who were greater than 9 years at onset (30% Stulberg II, 50% Stulberg III, and 20% Stulberg IV results). In Group C, the majority of femoral heads became aspherical in both age groups (29% Stulberg II, 52% Stulberg III, and 19% Stulberg IV results). The group C hips also had a longer duration of fragmentation and reossification stages. Members of the Legg-Perthes study group agreed 78% of the time when applying the classification to unknown radiographs. The classification group was a stronger determinant than age of onset in predicting final outcome. This classification system is easy to apply during the active stage of the disease and has a high correlation in predicting the amount of flattening of the femoral head at skeletal maturity.(ABSTRACT TRUNCATED AT 250 WORDS)

Radial neck fracture complicating closed reduction of a posterior elbow dislocation in a child: case report.

A case of radial neck fracture complicating repeated attempts at closed reduction of a posterior elbow dislocation in a child is described. This case underscores the necessity of using proper technique when reducing posterior elbow dislocations. The mechanism of radial neck fracture in association with posterior elbow dislocation is discussed.

Radial growth and function of the forearm after excision of the radial head. A study of growing macaque monkeys.

In five immature macaque monkeys, the right radial head was excised and the left forearm served as a control. Growth of each radius, ulna, and proximal and distal physis was followed for eight years. Total radial growth was slightly less on the side that was operated on than it was on the control side. After excision of the radial head, 95 per cent of radial growth came from the distal physis, compared with 71 per cent on the control side. A regenerated radial head, which had an irregular surface of fibrocartilaginous tissue, accounted for the remainder of growth on the side that had been operated on. Incongruous contact of articular surfaces resulted in degenerative changes in the capitellum. The arms that had been operated on were left with a flexion contracture that was an average of 12 degrees greater than that of the normal elbows, and they had a carrying angle that was an average of 6 degrees greater than that on the normal side. The arc of pronation and supination was decreased for the forearms that had been operated on, but motion of the wrist was unaffected. In our study, excision of the radial head in growing monkeys resulted in minimum radial shortening, slight deformity of the elbow, and moderate impairment of rotation of the forearm.

Respiratory infections caused by Branhamella catarrhalis. Selected epidemiologic features.

PURPOSE: This work reviewed existing literature pertaining to the epidemiologic aspects of respiratory tract infections caused by Branhamella catarrhalis, examined certain epidemiologic features of B. catarrhalis infections occurring at this facility, and identified relevant areas in need of further study. PATIENTS AND METHODS: Literature dealing with the epidemiology of B. catarrhalis infections was reviewed. Records in this Veterans Administration hospital microbiology laboratory were reviewed and all B. catarrhalis isolates and pure cultures of Hemophilus influenzae and Streptococcus pneumoniae were noted for the January 1986 to June 1989 study period. RESULTS: B. catarrhalis is now recognized as a disease-causing pathogen that is particularly noted for its association with acute otitis media in children and lower respiratory tract infections in adults with underlying cardiopulmonary disease. It was recovered from 2.7 percent of all respiratory specimens submitted over a 42-month period at this Veterans hospital. When compared with H. influenzae and S. pneumoniae, B. catarrhalis was found to be the second most commonly isolated respiratory pathogen. It was frequently found in pure culture (53 percent) or in combination with H. influenzae, gram-negative bacilli, or S. pneumoniae. The seasonal recovery of B. catarrhalis was apparent for the November to May period compared with the June to October period (p less than 0.001). CONCLUSION: B. catarrhalis has emerged as a major respiratory pathogen in pediatric and adult patient populations. There is a distinct seasonal pattern associated with its recovery and reasons for this are unclear. Prevalence studies aimed at identifying colonization rates among "low" and "high" risk groups are needed. The availability of restriction endonuclease analysis as a typing system for B. catarrhalis should favorably impact upon future epidemiologic studies. Many B. catarrhalis isolates produce beta-lactamase, and therapeutic options must reflect this.

Pulmonary endothelial injury and altered fibrinolysis after femur fracture in rabbits.

The pathophysiology of acute lung injury after long bone fracture may be associated with endothelial damage and altered fibrinolysis. Accordingly, we studied metabolic functions of pulmonary endothelial cells: 5-hydroxytryptamine (5-HT) uptake and angiotensin-converting enzyme (ACE) activity in anesthetized rabbits before and every 4 h after long bone fracture (n = 12) or sham (n = 6). To assess changes in fibrinolysis, we studied levels of plasminogen activator inhibitor (PAI), an inhibitor of the fibrinolytic cascade. All animals in the control group and only 6 of 12 animals in the long bone fracture group survived 12 h. 5-HT uptake was depressed after 8 h in both groups. By 12 h, however, 5-HT uptake in the long bone fracture group remained depressed, but returned to baseline in the control group. Conversely, ACE activity was unchanged in both groups. PAI levels were increased in both groups at 4 h. During the next 8 h, levels in the long bone fracture group continued to increase and remained elevated, whereas levels in the control group decreased and were not greater than baseline at 12 h. Initial PAI and 5-HT uptake changes may be related to surgical preparation of the rabbit. Prolonged depression of 5-HT uptake suggests that musculoskeletal trauma is associated with pulmonary endothelial damage. Finally, impaired fibrinolysis due to increased PAI may contribute to the pathogenesis of endothelial injury after long bone fracture.