Academic abilities and glycaemic control in children and young people with Type 1 diabetes mellitus.

AIMS: To determine if children and young people aged < 23 years with Type 1 diabetes differ in academic ability from age-matched control subjects without Type 1 diabetes and whether academic scores are related to glycaemic control. METHODS: Using a cross-sectional study design, we administered cognitive and academic tests (Woodcock-Johnson III Spatial Relations, General Information, Letter-Word Recognition, Calculation and Spelling tests) to young people with Type 1 diabetes (n=61) and control subjects (n=26) aged 9-22 years. The groups did not differ in age or gender. Participants with Type 1 diabetes had a disease duration of 5-17.7 years. History of glycaemic control (HbA1c , diabetic ketoacidosis and severe hypoglycaemic episodes) was obtained via medical records and interviews. RESULTS: The participants with Type 1 diabetes had a lower mean estimated verbal intelligence (IQ) level compared with those in the control group (P=0.04). Greater exposure to hyperglycaemia over time was associated with lower spelling abilities within the group with Type 1 diabetes (P=0.048), even after controlling for age, gender, socio-economic status, blood glucose level at time of testing and verbal IQ (P=0.01). History of severe hypoglycaemia or ketoacidosis was not associated with differences in academic abilities. CONCLUSIONS: In children and young people, Type 1 diabetes was associated with a lower verbal IQ. Moreover, increased exposure to hyperglycaemia was associated with lower spelling performance. These results imply that hyperglycaemia can affect cognitive function and/or learning processes that may affect academic achievement.

Remote sensing in hybridized arrays of nanostrings.

We study high-Q nanostrings that are joined end-to-end to form coupled linear arrays. Whereas isolated individual resonators exhibit sinusoidal vibrational modes with an almost perfectly harmonic spectrum, the modes of the interacting strings are substantially hybridized. Even far-separated strings can show significantly correlated displacement. This remote coupling property is exploited to quantify the deposition of femtogram-scale masses with string-by-string positional discrimination based on measurements of one string only.

Comorbidities of idiopathic thrombocytopenic purpura: a population-based study.

A person experiencing more than one medical condition may have ambiguous clinical presentation. ITP is a serious autoimmune disease with little epidemiological evidence on its burden, risk factors, and comorbidities. Using the United Kingdom general practice research database, we conducted a 14 years population-based case control-type study to explore medical conditions more likely to cooccur with ITP and their temporal relationship in association with ITP. ITP patients were matched to non-ITP on practice, age, gender, and follow-up period. Potential comorbidities were represented by patients' medical information at the preferred term level of the MedDRA international classification. As well as death (OR = 60.0; 95% CI [4.47-806.0]) and known clinical signs and symptoms of ITP, ITP is associated with considerable number of medical conditions. The association between ITP and some of these conditions is apparent both before and after ITP diagnosis. Specific targeted studies can now be setup to reexamine observed associations.

Valence bond solid phases in a cubic antiferromagnet.

We report on a valence bond projector Monte Carlo simulation of the cubic lattice quantum Heisenberg model with additional higher-order exchange interactions in each unit cell. The model supports two different valence bond solid (VBS) ground states. In one of these states, the dimer pattern is a three-dimensional analogue of the columnar pattern familiar from two dimensions. In the other, the dimers are regularly arranged along the four main diagonals in 1/8 of the unit cells. The phases are separated from one another and from a Néel phase by strongly first-order boundaries. Our results strengthen the case for exotic transitions in two dimensions, where no discontinuities have been detected at the Heisenberg Néel-VBS transition driven by four-spin plaquette interactions.

Heavy fermion fluid in high magnetic fields: an infrared study of CeRu4Sb12.

We report a comprehensive infrared magnetospectroscopy study of a CeRu4Sb12 compound revealing quasiparticles with a heavy effective mass m*, with a detailed analysis of optical constants in fields up to 17 T. We find that the applied magnetic field strongly affects the low-energy excitations in the system. In particular, the magnitude of m* approximately = 70 m(b) (m(b) is the quasiparticle band mass) at 10 K is suppressed by as much as 25% at 17 T. This effect is in quantitative agreement with the mean-field solution of the periodic Anderson model augmented with a Zeeman term.

Ultrasonic imaging of myocardial vibrations associated with coronary artery disease.

Coronary artery disease (CAD) is a major cause of majority in the western world. Although progress has been made in recent years for the noninvasive diagnosis of CAD, a widely available, inexpensive and effective diagnostic solution remains elusive. We have developed a novel ultrasound-based technology to detect and analyze the myocardial vibrations associated with diastolic murmurs produced by CAD. Conventional ultrasound imaging systems suppress these vibrations. We have developed algorithms to process the raw ultrasound data and isolate these vibrations and integrated them into a programmable ultrasound system for real-time vibration imaging. In preliminary results from clinical studies of patients with CAD, we have observed localized areas of vibrations in the neighborhood of the stenosed coronary artery. The vibrations are narrowband with frequency >200 Hz, and appear to have harmonic components, thus indicating resonance phenomena potentially with nonlinear mechanisms involved. No such vibrations were observed in normal subjects. Analysis of myocardial vibrations could provide a noninvasive diagnostic test for CAD that overcomes many of the limitations of conventional noninvasive tests. Potentially, this technology could provide a new way of evaluating CAD and cardiac function.

Ultrasonic imaging of myocardial vibrations associated with coronary artery disease.

Coronary artery disease (CAD) is a major cause of mortality in the western world. Although progress has been made in recent years for the noninvasive diagnosis of CAD, a widely available, inexpensive and effective diagnostic solution remains elusive. We have developed a novel ultrasound-based technology to detect and analyze the myocardial vibrations associated with diastolic murmurs produced by CAD. Conventional ultrasound imaging systems suppress these vibrations. We have developed algorithms to process the raw ultrasound data and isolate these vibrations and integrated them into a programmable ultrasound system for real-time vibration imaging. In preliminary results from clinical studies of patients with CAD, we have observed localized areas of vibrations in the neighborhood of the stenosed coronary artery. The vibrations are narrowband with frequency >200 Hz, and appear to have harmonic components, thus indicating reasonance phenomena potentially with nonlinear mechanisms involved. No such vibrations were observed in normal subjects. Analysis of myocardial vibrations could provide a noninvasive diagnostic test for CAD that overcomes many of the limitations of conventional noninvasive tests. Potentially, this technology could provide a new way of evaluating CAD and cardiac function.

Field-induced antiferromagnetism in the Kondo insulator.

The Kondo lattice model, augmented by a Zeeman term, serves as a useful model of a Kondo insulator in an applied magnetic field. A variational mean field analysis of this system on a square lattice, backed up by quantum Monte Carlo calculations, reveals an interesting separation of magnetic field scales. For Zeeman energy comparable to the Kondo energy, the spin gap closes and the system develops transverse staggered magnetic order. The charge gap, however, remains robust up to a higher hybridization energy scale, at which point the canted antiferromagnetism is exponentially suppressed and the system crosses over to a nearly metallic regime. Quantum Monte Carlo simulations support this mean field scenario. An interesting rearrangement of spectral weight with magnetic field is found.

Ultrasonic techniques for assessing wall vibrations in stenosed arteries.

Arterial stenoses are often associated with audible bruits. Quantitative analysis of the bruit spectrum has been successfully used to predict the residual lumen diameter in carotid stenoses. Arterial wall vibrations occurring due to turbulent pressure fluctuations in the post-stenotic jet are known to be the source of the bruits. We present novel signal processing techniques that enable the detailed noninvasive assessment of these vibrations in real time using color-Doppler and pulsed-wave Doppler ultrasound. A color-Doppler-based two-dimensional vibration imaging technique can be used to locate the source of the bruits relative to the underlying anatomy. Subsequently, a pulsed-wave Doppler-based technique can be used to analyze the bruit spectrum quantitatively. Experiments in ex vivo arteries indicate that these techniques can predict the location of the bruit as well as its spectral content. Case studies on human subjects with stenosed vein grafts are presented and the clinical applicability of this technique is discussed.

Carotid atherosclerotic plaque: noninvasive MR characterization and identification of vulnerable lesions.

Measurement of vessel stenosis by using ultrasonography or angiography remains the principal method for determining the severity of carotid atherosclerosis and the need for endarterectomy. The ipsilateral stroke rate, however--even in patients with severely stenotic vessels--is relatively low, which suggests that the amount of luminal narrowing may not represent the optimal means of assessing clinical risk. As a result, some patients may undergo unnecessary surgery. Improved imaging techniques are, therefore, needed to enable reliable identification of high-risk plaques that lead to cerebrovascular events. High-spatial-resolution magnetic resonance (MR) imaging has been described as one promising modality for this purpose, because the technique allows direct visualization of diseased vessel wall and can be used to characterize the morphology of individual atherosclerotic carotid plaques. The purpose of this report is to review the current state of carotid plaque MR imaging and the use of carotid MR to evaluate plaque morphology and composition.

In vivo ultrasonic measurement of tissue vibration at a stenosis: a case study.

It is known that bruits often can be heard downstream from stenoses. They are thought to be produced by disturbed blood flow and vessel wall vibrations. Our understanding of bruits has been limited, though, to analysis of sounds heard at the level of the skin. For direct measurements from the stenosis site, we developed an ultrasonic pulse-echo multigate system using quadrature phase demodulation. The system simultaneously measures tissue displacements and blood velocities at multiple depths. This paper presents a case study of a severe stenosis in a human infrainguinal vein bypass graft. During systole, nearly sinusoidal vessel wall vibrations were detected. Solid tissue vibration amplitudes measured up to 2 microm, with temporal durations of 100 ms and frequencies of roughly 145 Hz and its harmonics. Cross-axial oscillations were also found in the lumen that correlate with the wall vibrations, suggesting coupling between wall vibration and blood velocity oscillation.

Strike while the iron is hot: can stepped-care treatments resurrect relapsing smokers?

The efficacies of 2 group counseling step-up treatments for smoking cessation, cognitive-behavioral/skill training therapy (CBT) and motivational interviewing/supportive (MIS) therapy, were compared with brief intervention (BI) treatment in a sample of 677 smokers. Differential efficacy of the 2 step-up treatments was also tested in smokers at low and high risk for relapse (no smoking vs. any smoking during the first postquit week. respectively). All participants received 8 weeks of nicotine patch therapy. BI consisted of 3 brief individual cessation counseling sessions; CBT and MIS participants received BI treatment and 6 group counseling sessions. Neither CBT nor MIS treatment improved long-term abstinence rates relative to BI. Limited support was found for the hypothesis that high-risk smokers would benefit more from MIS than CBT. Other hypotheses were not supported.

Measurement of abdominal aortic aneurysms with three-dimensional ultrasound imaging: preliminary report.

OBJECTIVE: Accurate measurements of abdominal aortic aneurysms (AAAs) are required for surgical planning and monitoring over time. We have examined the feasibility of using a three-dimensional (3-D) ultrasound imaging system to derive quantitative measurements of interest from AAAs. METHODS: A normal aorta, a small AAA, and an AAA repaired with an endovascular stent graft were scanned with a 3-D ultrasound imaging system. For each case, a 3-D surface reconstruction was generated from manual outlines of a sequence of two-dimensional ultrasound images, registered in 3-D space with a magnetic tracking system. The surfaces were resampled in planes perpendicular to the vessel center axis to calculate cross-sectional area and maximum diameter as a function of distance along the length of the aorta. RESULTS: Cross-sectional area and maximum diameter were plotted along the length of the aneurysmal aortas from the renal arteries to the aortic bifurcation. The overall maximum diameter was found for both aneurysms. For the small AAA, the distances of the aneurysm from the renal arteries and the bifurcation were measured. For the repaired AAA, the location of the stent graft relative to the renal arteries was measured. CONCLUSIONS: 3-D surface reconstructions from ultrasound images show promise for quantitatively characterizing the geometry of AAAs both before surgery and after endovascular repair.

Serial measurement of cross-sectional area in peripheral vein grafts using three-dimensional ultrasound.

Frequent surveillance of bypass grafts placed in the lower limbs can provide early detection of stenoses. A three-dimensional (3-D) ultrasound (US) imaging system has been used to produce serial surface reconstructions of regions of interest in vein grafts in the lower extremities. Using anatomical reference points, data sets from serial studies are registered in a common 3-D coordinate system. Cross-sectional area measurements are extracted from the surface reconstructions in planes normal to the vessel center axis. These measurements are compared at matched sites over time to track changes in the vessel configuration. The quantitative measurements are paired with surface displays of the vessels for a complete depiction of the changing geometry. Example studies from three patients are shown, for time periods up to 38 weeks. The cross-sectional area measurements highlight regions of remodeling and developing stenoses within the grafts.

Cross-beam vector Doppler ultrasound for angle-independent velocity measurements.

Combining Doppler measurements taken along multiple intersecting ultrasound (US) beams is one approach to obtaining angle-independent velocity. Over 30 laboratories and companies have developed such cross-beam systems since the 1970s. Early designs focused on multiple single-element probes. In the late 1980s, combining multiple color Doppler images acquired from linear-array transducers became a popular modality. This was further expanded to include beam steering and the use of subapertures. Often, with each change in design, came a new twist to calculating the velocity. This article presents a review of most proposed cross-beam systems published to date. The emphasis is on the basic design, the approach used to determine the angle-independent velocity, the advantages of the design, and the disadvantages of the design. From this, requirements needed to convert the idea of angle-independent vector Doppler into a commercial system are suggested.

The incidence of pulmonary embolism in unexplained sudden cardiac arrest with pulseless electrical activity.

PURPOSE: The cause of many cases of sudden cardiac arrest from pulseless electrical activity is unknown. We hypothesized that pulmonary embolism was responsible for a substantial proportion of these cases and used transesophageal echocardiography to identify pulmonary embolism among patients with sudden cardiac arrest. SUBJECTS AND METHODS: We performed a prospective study at a tertiary care, university-operated county hospital, with a level 1 trauma center. Consecutive patients (n = 36) who were admitted with (n = 20) or unexpectedly developed (n = 16) sudden cardiac arrest of unknown cause were studied with transesophageal echocardiography during cardiopulmonary resuscitation. We determined the presence of central pulmonary embolism, right ventricular enlargement, and other causes of sudden cardiac arrest (such as myocardial infarction and aortic dissection) using prospectively defined criteria. RESULTS: Of the 25 patients with pulseless electrical activity as the initial event, 9 (36%) had pulmonary emboli (8 seen with transesophageal echocardiography and 1 diagnosed at autopsy) compared with none of the 11 patients with other rhythms, such as asystole or ventricular tachycardia or fibrillation (P = 0.02). Of the 8 patients who had pulmonary embolism diagnosed by transesophageal echocardiography, 2 survived to hospital discharge. CONCLUSIONS: Mortality from massive pulmonary embolism is high, particularly if patients present with sudden cardiac arrest. Earlier diagnosis of pulmonary embolus may permit wider use of thrombolytic agents or other interventions and may potentially increase survival.

Granulocyte colony-stimulating factor given to donors before apheresis does not prevent aplasia in patients treated with donor leukocyte infusion for recurrent chronic myeloid leukemia after bone marrow transplantation.

We conducted 2 sequential studies of donor leukocyte infusion (DLI) in 26 patients with chronic myeloid leukemia in hematologic relapse after unmodified allogeneic bone marrow transplantation. In the first study, cells for DLI were collected from 13 donors who were not treated with granulocyte colony-stimulating factor (G-CSF) (group 1). In the second study, cells were collected from 13 donors who received G-CSF before apheresis (group 2) in an attempt to avoid aplasia after DLI. Patients in group 2 received 550-fold more CD34+ cells than those in group 1. We found no significant difference in the incidence (31% versus 22%), onset time (41 vs. 48 days), or duration (15 vs. 14 days) of cytopenia after DLI in the 2 groups. G-CSF given to donors before collection of cells did not prevent aplasia. These findings support the hypothesis that the pathogenesis of aplasia after DLI is not restricted to the destruction of recipient hematopoietic cells but also involves failure of donor hematopoiesis by undefined mechanisms.

Immittance and otoacoustic emissions in rhesus monkeys and humans.

The purpose of this study was to compare multifrequency tympanometry and otoacoustic emissions (OAEs) in rhesus monkeys (Macaca mulatta) and humans. Tympanometry and OAEs can be recorded efficiently in Macaca mulatta to assess peripheral auditory function with results comparable to those in humans. Differences include (1) greater admittances and conductances in humans from 226 to 630 Hz, the frequency range validly assessed; (2) larger amplitude transient evoked OAEs (TEOAEs) and noise levels in humans; (3) larger amplitude monkey 2f(1)-f(2) distortion product OAEs (DPOAES) (f(2)s>2 kHz); (4) more prominent DPOAEs other than 2f(1)-f(2) in monkeys; (5) more narrowly tuned human f(2)/f(1) X 2f(1)-f(2) amplitude functions at the lower frequencies tested; and (6) lower 2f(1)-f(2) DPOAE thresholds at f(2)=0.5 kHz and > or = 8 kHz in monkeys.

New ultrasound approaches to dialysis access monitoring.

The failure of dialysis access is a frequent source of morbidity and hospitalization. Traditional methods of graft surveillance include: (1) clinical examination, (2) venous line pressure measurements during dialysis, (3) urea or tracer recirculation measurement, (4) continuous wave (CW) Doppler methods, (5) duplex ultrasonography, and (6) radiograph angiography. All these methods require special training and/or laboratory tests. The purpose of this study was to test a simple continuous-wave Doppler method that could be applied to measure the flow rate in dialysis access every time the patient undergoes dialysis. Twenty dialysis patients, 15 with polytetrafluoroethylene grafts and 5 with arteriovenous fistulae, were studied. Two hundred fifty-three examinations were performed over an 8-month period. Doppler waveforms of the access flow were obtained with the pump on, with the pump off, and with the pump on again. Systolic and diastolic Doppler frequency measurements were made, and the pump-on and pump-off measurements were compared. In an access functioning normally, the Doppler frequencies are higher with the pump off than with the pump on. In 22% of the cases, there were abnormal findings in which the Doppler frequencies were lower with the pump off than with the pump on. This occurs if the needles are incorrectly placed, suggesting that recirculation is occurring. Recirculation also occurs if there is stenosis of the access. Examining the hemodialysis access during each dialysis session with an inexpensive directional Doppler may identify a significant stenosis and improve the efficiency of dialysis by detecting those patients in whom the arterial and venous needles are reversed.

Hemostasis of punctured vessels using Doppler-guided high-intensity ultrasound.

The use of Doppler ultrasound was investigated to determine if it would aid in guiding the application of high-intensity focused ultrasound (HIFU) to stop bleeding from punctured vessels. Major vessels (abdominal aorta, illiac, carotid, common femoral and superficial femoral arteries and the jugular vein) were surgically exposed, punctured and treated in anesthetized pigs. Treatment was applied when the Doppler sounds indicated the focus coincided with the bleeding site. In 89 treatment trials, the average time to achieve major hemostasis (a point where bleeding was reduced to a level of only oozing) was 8 s, and for complete hemostasis was 13 s. These times were significantly shorter than those of an identical former study in which only visual guidance was used. In that study, the average times for major and complete hemostasis were 40 and 62 s, respectively. The advantage of Doppler guidance in applying HIFU in treating bleeding vessels was demonstrated.