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Adolescents with disruptive behavior disorder (DBD) and controls were investigated using an optimized MR diffusion tensor imaging (DTI) protocol in order to assess any possible structural abnormalities associated with DBD. Thirty-six patients and 40 normal subjects were examined. The extracted diffusion fractional anisotropy (FA) results demonstrate that for the DBD patients there is significantly reduced FA in both the frontal and left temporal regions. The largest brain area with significantly reduced FA is located within the arcuate fasciculus, which has projections extending from the temporal lobe to the frontal lobe along the lateral ventricle, lateral to the tapetum. The reduced FA reflects directly a lower extent of myelination and less coherent fiber track structures in the fasciculus, which in turn may indicate communication weakness among the associated cortical areas. The detected white matter microstructural abnormality, therefore, may be related to the developmental deficits observed in the patient group.

The relationship between media violence exposure and executive functioning was investigated in samples of adolescents with no psychiatric diagnosis or with a history of aggressive-disruptive behavior. Age-, gender-, and IQ-matched samples of adolescents who had no Diagnostic and Statistical Manual of Mental Disorders-fourth edition (DSM-IV; American Psychiatric Association, 1994) diagnosis (N = 27) and of adolescents who had DSM-IV Disruptive Behavior Disorder diagnoses (N = 27) completed measures of media violence exposure and tests of executive functioning. Moderate to strong relationships were found between higher amounts of media violence exposure and deficits in self-report, parent-report, and laboratory-based measures of executive functioning. A significant diagnosis by media violence exposure interaction effect was found for Conners' Continuous Performance Test scores, such that the media violence exposure-executive functioning relationship was stronger for adolescents who had Disruptive Behavior Disorder diagnoses. Results indicate that media violence exposure is related to poorer executive functioning, and this relationship may be stronger for adolescents who have a history of aggressive-disruptive behavior., (Copyright 2004 Wiley Periodicals, Inc.)

Detecting changes in a stream of sensory information is vital to animals and humans. While there have been several studies of automatic change detection in various sensory modalities, olfactory change detection is largely unstudied. We investigated brain regions responsive to both passive and active detection of olfactory change using fMRI. Nine right-handed healthy, normosmic subjects (five men) were scanned in two conditions while breathing in synchrony with a metronome. In one condition, subjects mentally counted infrequent odors (Attend condition), whereas in the other condition, subjects' attention was directed elsewhere as they counted auditory tones (Ignore condition). Odors were delivered via a nasal cannula using a computer-controlled air-dilution olfactometer. Infrequently occurring olfactory stimuli evoked significant (P < .05, corrected) activity in the subgenual cingulate and in central posterior orbitofrontal cortex, but only in the Ignore condition, as confirmed by direct comparison of the Ignore session with the Attend session (P < .05, corrected). Subgenual cingulate and posterior orbital cortex may therefore play a role in detecting discrepant olfactory events while attention is otherwise engaged in another sensory modality.

Purpose: To develop a multishot magnetic resonance imaging (MRI) pulse sequence and reconstruction algorithm for diffusion-weighted imaging (DWI) in the brain with submillimeter in-plane resolution., Materials and Methods: A self-navigated multishot acquisition technique based on variable-density spiral k-space trajectory design was implemented on clinical MRI scanners. The image reconstruction algorithm takes advantage of the oversampling of the center k-space and uses the densely sampled central portion of the k-space data for both imaging reconstruction and motion correction. The developed DWI technique was tested in an agar gel phantom and three healthy volunteers., Results: Motions result in phase and k-space shifts in the DWI data acquired using multishot spiral acquisitions. With the two-dimensional self-navigator correction, diffusion-weighted images with a resolution of 0.9 x 0.9 x 3 mm3 were successfully obtained using different interleaves ranging from 8-32. The measured apparent diffusion coefficient (ADC) in the homogenous gel phantom was (1.66 +/- 0.09) x 10(-3) mm2/second, which was the same as measured with single-shot methods. The intersubject average ADC from the brain parenchyma of normal adults was (0.91 +/- 0.01) x 10(-3) mm2/second, which was in a good agreement with the reported literature values., Conclusion: The self-navigated multishot variable-density spiral acquisition provides a time-efficient approach to acquire high-resolution diffusion-weighted images on a clinical scanner. The reconstruction algorithm based on motion correction in the k-space data is robust, and measured ADC values are accurate and reproducible.

Objective: To assess the efficacy and safety of haiguiyuyang capsule in the treatment of duodenal ulcer (also diagnosed as weiwan pain and hanrecuoza syndrome according to the theory of TCM)., Methods: This is a multi-center clinical trial cooperatively conducted from May 2003 to March 2004 in accordance to the principle of informed consent, to the criteria for subject inclusion, exclusion, discontinuation, and to the relevant guidelines for evaluating the therapeutic effects of new TCM drugs. The design of double-blind, double-dummy and randomized controlled trial was adopted. 438 patients were randomized to the Test group (n = 330, treated with haiguiyuyang capsule) and to the Control group (n = 108, treated with ranitidine). The therapeutic course for both groups was 6 weeks., Results: Regarding the efficacy in treating duodenal ulcer, in the Test group, the Marked Efficacy Rate was 66.37% and the Total Efficacy Rate was 82.13%; in the Control group, the Marked Efficacy Rate was 68.61% and the Total Efficacy Rate was 93.34%; there was no significant difference between the two groups (P>0.05). Regarding the efficacy in treating the syndrome diagnosed by TCM, in the Test group, the Marked Efficacy Rate was 70.31% and the Total Efficacy Rate was 93.34%; in the control group, the rates were 71.29% and 91.66% respectively; there was no significant difference between the two groups (P>0.05). Besides, regarding the abatement of distention and fullness of stomach after treatment, the haiguiyuyang capsule was better than ranitidine (P<0.05). No adverse side-effect was observed., Conclusion: The efficacy of haiguiyuyang capsule in treating duodenal ulcer is similar to that of ranitidine. No obvious adverse effect of it was observed in this trial.

Sedum alfredii Hance has been reported to be a Zn-hyperaccumulator plant species. In this study, root morphological and physiological response of the hyperaccumulating ecotype of S. alfredii H. (HE) from the mined area and the non-hyperaccumulating ecotype of S. alfredii H. (NHE) from the agricultural area to supplied levels of Zn and Pb were investigated. The results showed that Zn concentrations in the leaves and the stems of the HE were 34 and 41 times higher, whereas lead concentrations were 1.9 and 2.4 times greater, respectively, than those of the NHE when grown at 1224 microM Zn and/or 200 microM Pb. At combined supply of 1224 microM Zn with 200 microM Pb, however, zinc concentrations in the stems and leaves of the, HE decreased, while lead concentrations in the stems increased significantly, as compared with those of single metal treatment. Lead uptake of the HE was enhanced by Zn addition. Root activity of the HE decreased by Pb treatment in the first two days, but recovered afterward and close to the control at day 10 of the treatment. However, root activity of the NHE decreased by each metal treatment, and was not recovered with the advance of treatment time. Root length, root surface area, and root volumes increased obviously due to Zn and/or Pb/Zn combined treatments for the HE, but significantly decreased due to Pb, Zn, or Pb/Zn combined treatment for the NHE. Zinc and Pb concentrations in both ecotypes of S. alfredii H. were positively correlated with root length, root surface area, and root volumes. Root exudates of the HE, especially treated with Zn, increased the extractability of Pb and Zn from the mined soil. At the Zn supply level of 1224microM, the extractability of root exudates on soil Pb was 3-12 times greater for the HE than for the NHE. These results imply that the tolerance and hyperaccumulation of the hyperaccumulating ecotype of S. alfredii H. to Zn and Pb appear to be closely related to its high adaptation of root growth, morphology, and physiology to Pb and Zn toxicity, and through its root excretion of some special substances that can activate Pb and Zn in the mined soil, thus increasing their mobilization and bioavailability.

Osteoporosis is a common finding following chronic obstructive pulmonary disease (COPD), but there are few reports on the relationship between bone mineral density (BMD) and the syndrome types described in traditional Chinese medicine (TCM) in patients with COPD. A cross-sectional medical survey was used in this study. Twenty-six male patients with COPD and 26 age-matched male healthy subjects were recruited. The symptom questionnaire survey of TCM was implemented, and thereafter the COPD patients were divided into two subgroups: type of deficiency of the lung and spleen (TDLS) and type of deficiency of the lung, spleen and kidney (TDLSK). BMD of lumbar spine (L2-4), non-dominant femoral neck (Neck), Ward's triangle (Ward's), and great trochanter (Troch) were measured by dual-energy x-ray absorptiometry. In addition, the other bone turnover markers were also examined. The results showed that BMD was much more decreased in TDLSK than that in TDLS patients (p < 0.05), and BMD in the patients of the TDLS subgroup without symptoms of kidney-vacuity has showed the decreased trend from healthy subjects to TDLS patients. Furthermore, there was a higher incidence of osteoporosis in patients with TDLSK compared with that in TDLS (p < 0.05, OR > 2.0). Therefore, the data suggest that: (1) BMD might be a marker more sensitive than the symptom for the diagnosis of kidney-vacuity in COPD patients; (2) the deficiency of kidney would be the key factor of bone mineral loss; and (3) that invigorating the kidney should be performed in the phase of TDLS in COPD patients in advance.

Objective: To screen special mimic epitopes of Trichinella spiralis antigen from peptide library for exploring new diagnostic antigens., Methods: Ts-IgG purified from serum of trichinosis patients was used to screen the phage 12-mer peptide library for 5 rounds. 24 clones were picked out randomly to detect the immunoactivity. The sensitivity and specificity of the 6 clones (T1 - T6) whose A values were higher than others were tested by ELISA., Results: The sensitivity of the clones T1 - T6 was the same with larval antigen of Trichinella spiralis (TsA) (positive rate: 100%, P > 0.05), and there was no difference in specificity between T1 - T6 and TsA (negative rate: 0 - 40%, P > 0.05); T3 and T6 did not react with sera from patients of paragonimiasis, showing higher specificity than TsA (P < 0.05); T6 did not react with sera from patients of schistosomiasis, also showing higher specificity than TsA (P < 0.05)., Conclusion: The mimic antigenic epitopes of Trichinella spiralis have been successfully obtained by screening phage 12-mer peptide library.

Numerous studies over the past decade have shown that magnetic resonance imaging (MRI) has great potential for detecting and quantifying the distribution of iron in the body. With MRI, tissue iron is indirectly identified by the paramagnetic effects of iron on the shortening of water proton MR relaxation times. However, these effects are complex and involve a number of factors, such as tissue hydration, distribution of iron and water within the tissue, and the amount of iron loading within the iron storage molecules. A coherent understanding of how these factors influence the MRI signal is still lacking. The dependence on experimental conditions, such as magnet field strength, pulse sequences, and data acquisition parameters, further complicates iron quantification with MRI. To date, there is no generally accepted MRI approach available for clinical application. In this review, we first explain the basic MR relaxation mechanisms underlying the detection of iron with MRI. We then review the literature on empirical MRI studies of hepatic iron. Finally, we summarize the critical issues that need to be addressed to develop MRI techniques for non-invasive iron detection in the body.

Objective: To gain a better understanding of the effect of emodin on lung fibroblast (LF) proliferation in vitro., Methods: The methods of cell cultured in vitro, 3H-TdR incorporation, flow cytometry and electron microscopy were used in research to compare LF proliferation, cell cycle and morphologic change of LF in vitro., Results: It was found that emodin reduced the proliferation of LF in vitro (P < 0.01), and such inhibitory effect was dose-dependent. Emodin delayed the progression of LF from G1 to S and G2 phase (P < 0.01). Also, electron microscopic examination demonstrated that the ultrastructure of LF in emodin group was not markedly worse as compared with that in the control group., Conclusion: Emodin inhibits the proliferation of LF and delays the progression of LF cell cycle. Emodin at the dose of 100 micrograms/ml does not destroy the ultrastructure of LF cells. These findings may provide a theoretical basis for the endeavors to use emodin for preventing lung fibrosis diseases.

Adsorption desorption processes of Pb at contaminated levels in two variable charge soils were investigated. The red soil (RAR) developed on the Arenaceous rock (clayey, mixed siliceous thermic typic Dystrochrept) adsorbed more Pb2+ than the red soil (REQ) derived from the Quaternary red earths (clayey, kaolinitic thermic plinthite Aquult). The maximum adsorption values (Xm) that were obtained from the simple Langmuir model were 52.6 mmol Pb2+ kg(-1) soil and 29.9 mmol Pb2+ kg(-1) soil, respectively, for the RAR and REQ. Adsorption of Pb2+ decreased soil pH by 1.10 unit for the RAR soil and 1.21 unit for the REQ soil at the highest loading. The adsorption equilibrium pH of RAR was higher than that of REQ at the same Pb2+ concentration. The distribution coefficient (Kd) of Pb in the soils decreased exponentially with increasing Pb2+ loading. Most of the adsorbed Pb2+ in the soils was not desorbed in the 0.01 mol L(-1) NaNO3 solution. After five successive extractions with NaNO3, only 0-11% of the total adsorbed Pb2+ in the RAR soil was desorbed and the corresponding value of the REQ soil was 0-19%, indicating that the RAR soil had a greater affinity for Pb2+ than the REQ soil at the same Pb2+ loading. Different mechanisms might be involved in Pb2+ adsorption/desorption at different levels of Pb2+ loading and between the two soils.

Objective: To measure the damping parameters of the spacesuit joint., Method: The principles of the passive robot system for measuring spacesuit joint's damping parameters were presented. Basing on its special mechanical structure, a 3 DOF model of the flexible IVA (intra-vehicular activity) spacesuit's sleeve was built. The optimal approximation of inverse calculation based on 6 dimension space interval was described. The damping parameters of an actual IVA spacesuit's sleeve were measured on the actual testbed. Also, the potential application of the measuring system was discussed., Result: The model of spacesuit sleeve and the forward/inverse kinematics were proved by experimental measurements and real time 3D simulation., Conclusion: The principles and the proposed method of the measurement were testified.

Objective: To measure the joint torque of spacesuit so as to evaluate its dynamic force/torque performance., Method: A method for measuring the spacesuit joint torque by use of robot technology was proposed in this paper. The design of the measuring strategy and measuring robot was put forward and a mathematical model of the system was given. Then the working space of the robot was analyzed., Result: The robot designed is light, compact, easy to operate, and has a large working space. Experimental results demonstrated the effectiveness of the measuring principle and the reliability of the measuring system., Conclusion: The system can satisfy the requirements of the spacesuit joint torque measurement.

Objective: To explore the correlation between bone mineral density and Syndrome type of TCM in patients with chronic obstructive pulmonary disease (COPD) for providing the base of clinical integrative traditional Chinese and western medical therapy for the disease through the Syndrome typing and determination of changes in bone metabolism and bone density., Methods: Bone mineral density (BMD) of lumbar vertebrae 2-4, femoral neck, Ward's triangle and trochanter in 27 COPD male patients, 25 male control subjects and 25 healthy persons were determined using dual energy X-ray absorptiometry, patient's Syndrome type, their blood levels of total protein, albumin, alkaline phosphatase, bone glaprotein, hydroxyproline, calcium, phosphate, urine levels of calcium/creatine and phosphorous/creatine as well as arterial blood gas were also determined., Results: The BMD in COPD patients accompanied with respiratory failure or with course > 10 years was higher than that in COPD patients without respiratory failure or with course < or = 10 years, BMD in COPD patients of Fei-Pi-Shen type was lower than that in those of Fei-Pi, but the urine hydroxyprdine in the former was higher than that in the latter (all P < 0.05)., Conclusion: (1) COPD is a risk factor for osteoporosis; (2) Shen Deficiency is the key and nucleus of secondary osteoporosis to COPD; (3) It is inferred that early regulation of Shen may be facilitated to prevent osteoporosis in COPD patients.

Objective: To study the technology of intra-vehicular pressure protection for manned space craft pressure emergency and to develop the pressure garment., Method: According to the requirements of manned spacecraft emergency, the research scheme was proposed. Then the realization method of the following techniques were studied: structure of the pressure suit, pressure control, ergonomics, ventilation and oxygen supply, vision support and anti-fog. The performance of the space suit was verified by research and environment experiment., Result: An intra-vehicular pressure garment system was realized. It could fulfil the requirements of pressure protection and ergonomics and has passed overall performance test, interface test, and environment test., Conclusion: The intra-vehicular pressure garment developed by us can meet the requirements of space transportation system during pressure emergency.

Objective: To prove the effect of Kesuning Granule (KSNG) in treating chronic bronchitis in exacerbation (Phlegm-Heat syndrome) and objectively evaluate its safety., Methods: The double-blinded, double-dummy and randomized controlled method was adopted to observe 120 patients, who were divided into the treated group (n = 60, treated with KSNG 8 g, three times a day) and the control group (n = 60, treated with Jinbei Tankeqing Granule (JBTKQ) 7 g, three times a day). The therapeutic course for both groups was 6 days., Results: In the treated group, the markedly effective rate was 58.33% and effective rate was 93.33%, while in the control group, they were 51.67% and 91.67% respectively, no significant difference was found between the two groups. For therapeutic effects on TCM syndromes, the markedly effective rate and effective rate in the treated group was 68.33% and 93.33% respectively and in the control group, 66.67% and 90.00% respectively, also showed insignificant difference. The effect initiative time was earlier in the treated group than that in the control group significantly (P < 0.05). No adverse effect was found in the observation., Conclusion: KSNG shows a definite clinical effect with no obvious toxic-adverse effects.

Arg-Gly-Asp (RGD) is one of the oligopeptides with biological activity found in recent years. It is the minimum ammonia serial on the ligand, which can be recognized by most of the integrins. It has important influence on the recognition of endothelial cell, anti-thrombus and anti-tumour function, and the therapy of burn and skin helcosis. In this review, the synthesis and application of oligopeptide [correction of oligepoptide] containing RGD sequence were discussed.

Purpose: To quantify age-related changes of the average diffusion coefficient value in normal adult brain using orientation-independent diffusion tensor trace mapping and to address the methodological influences on diffusion quantification., Material and Methods: Fifty-four normal subjects (aged 20-79 years) were studied on a 1.5-T whole-body MR medical unit using a diffusion-weighted single-shot echo-planar imaging technique. Orientation-independent diffusion tensor trace maps were constructed for each subject using diffusion-weighted MR measurements in four different directions using a tetrahedral gradient combination pattern. The global average (including cerebral spinal fluid) and the tissue average of diffusion coefficients in adult brains were determined by analyzing the diffusion coefficient distribution histogram for the entire brain. Methodological influences on the measured diffusion coefficient were also investigated by comparing the results obtained using different experimental settings., Results: Both global and tissue averages of the diffusion coefficient are significantly correlated with age (p<0.03). The global average of the diffusion coefficient increases 3% per decade after the age of 40, whereas the increase in the tissue average of diffusion coefficient is about 1% per decade. Experimental settings for self-diffusion measurements, such as data acquisition methods and number of b-values, can slightly influence the statistical distribution histogram of the diffusion tensor trace and its average value., Conclusion: Increased average diffusion coefficient in adult brains with aging are consistent with findings regarding structural changes in the brain that have been associated with aging. The study also demonstrates that it is desirable to use the same experimental parameters for diffusion coefficient quantification when comparing between different subjects and groups of interest.

Objective: To analyze the relation of the design parameters and appraise the heat removing characteristic of liquid cooling garment (LCG) using thermal manikin., Method: To appraise the design of LCG, the thermal manikin wearing LCG and heat insulation garment was put in the temperature cabin, then the inlet and outlet temperature of cooling liquid in the LCG were measured and the heat removed was calculated., Result: The relationship between the design parameters and heat removed, and also that between the design parameters and temperature ratio efficiency were found. And the heat removed was calculated. It provided a reasonable basis for appraisal of LCG., Conclusion: The design of the LCG for the EVA space suit was found to be reasonable. The flow rate regulation range was too narrow, and the change of heat removing capacity depended on the change of inlet temperature.

Objective. To investigate the development method of porous plate, the key part of water sublimator, and its main physical characteristics. Method. Technical parameters of porous plates used in water sublimator were analyzed. On the basis of this, porous plates made of different materials were developed by making use of sintered powder technology. A tester for testing the physical characteristics of porous plate was designed. All around physical characteristic tests for porous plates were conducted. Result. Main factors affecting performance of porous plates were tested. These provided basis for performance test of sublimator, established porous plate criterion and optimized porous plate. Conclusion. Porous plates developed by making use of sintered powder technology could meet requirements of performance of water sublimator.

Functional magnetic resonance imaging experiments were performed in human motor cortex at 1.5 T by sampling two successive gradient recalled echo images in a single shot. Several aspects of brain mapping methods based on T2*-weighted imaging and R2* mapping were quantitatively compared. These include the detected activation volume, functional contrast (FC), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Studies based on the R2* mapping method have the following potential advantages: maximum functional contrast, less dependent on TE; and reduced inflow effects. R2* mapping produced the highest functional contrast, but not the largest activation volume due to the reduced signal-to-noise ratio and inflow effects. The sensitivity for activation detection is significantly correlated with the contrast-to-noise ratio, which is determined by both the SNR and FC., (Copyright 2001 John Wiley & Sons, Ltd.)

Diffusion tensor mapping with MRI can noninvasively track neural connectivity and has great potential for neural scientific research and clinical applications. For each diffusion tensor imaging (DTI) data acquisition scheme, the diffusion tensor is related to the measured apparent diffusion coefficients (ADC) by a transformation matrix. With theoretical analysis we demonstrate that the noise performance of a DTI scheme is dependent on the condition number of the transformation matrix. To test the theoretical framework, we compared the noise performances of different DTI schemes using Monte-Carlo computer simulations and experimental DTI measurements. Both the simulation and the experimental results confirmed that the noise performances of different DTI schemes are significantly correlated with the condition number of the associated transformation matrices. We therefore applied numerical algorithms to optimize a DTI scheme by minimizing the condition number, hence improving the robustness to experimental noise. In the determination of anisotropic diffusion tensors with different orientations, MRI data acquisitions using a single optimum b value based on the mean diffusivity can produce ADC maps with regional differences in noise level. This will give rise to rotational variances of eigenvalues and anisotropy when diffusion tensor mapping is performed using a DTI scheme with a limited number of diffusion-weighting gradient directions. To reduce this type of artifact, a DTI scheme with not only a small condition number but also a large number of evenly distributed diffusion-weighting gradients in 3D is preferable., (Copyright 2000 Academic Press.)

The effect of changes in baseline regional cerebral blood flow (rCBF) values on the cerebral blood flow response during neuronal activation was studied with functional magnetic resonance imaging (fMRI). Using a breath-holding challenge as a hypercapnic stimulus, rCBF alterations during photic stimulation under normo- and hypercapnia were determined in nine volunteers. With breath-holding, baseline rCBF in areas corresponding to the visual cortex significantly increased from 54 +/- 5 ml/100 g/min to 85 +/- 9 ml/100 g/min (P < 0.001). Despite this significant change in baseline flow values, the rCBF increase during visual stimulation was very similar under normo- and hypercapnic conditions (28 +/- 8 ml/100 g/min versus 26 +/- 8 ml/100 g/min, respectively). This study supports the notion that within wide physiologic variations, task-induced cerebral blood flow changes are independent of baseline rCBF values.

Objective. To establish the heat transfer model for liquid cooling garment (LCG) and, basing on this model, to find the relations between the design parameters and heat removing, as well as that between the design parameters and heat transfer efficiency. Method. Heat transfer process of the LCG was analyzed according to engineering facts. Result. The relations between the design parameters and heat removing, and also that between the design parameters and heat transfer efficiency were interelative and the optimal values of the parameters were essential to the design of LCG. Conclusion. The results might be useful in the design of LCG in extra vehicular activity (EVA) space suit.

In this study, the hemodynamic response and changes in oxidative metabolism during functional activation were measured using three functional magnetic resonance imaging (fMRI) techniques: the blood oxygenation level-dependent (BOLD) technique, flow-sensitive alternating inversion recovery (FAIR), and bolus tracking (BT) of an MR contrast agent. With these three techniques we independently determined changes in BOLD signal, relative cerebral blood flow (rCBF), and cerebral blood volume (rCBV) associated with brain activation in eight healthy volunteers. In the motor cortex, the BOLD signal increased by 1.8 +/- 0.5%, rCBF by 36.3 +/- 8.2% (FAIR), and 35.1 +/- 8.6% (BT), and rCBV by 19.4 +/- 4.1% (BT) in response to simultaneous bilateral finger tapping. In the visual cortex, BOLD signal increased by 2.6 +/- 0.5%, rCBF by 38.5% +/- 7.6 (FAIR), and 36.9 +/- 8.8% (BT), and rCBV by 18.8 +/- 2.8% (BT) during flickering checkerboard stimulation. Comparing the experimentally measured rCBV with the calculated rCBV using Grubb's power-law relation, we conclude that the use of power-law relationship results in systematic underestimate of rCBV., (Copyright 2000 Academic Press.)

Respiration effects and cardiac pulsatility can induce signal modulations in functional MR image time series that increase noise and degrade the statistical significance of activation signals. A simple image-based correction method is described that does not have the limitations of k-space methods that preclude high spatial frequency correction. Low-order Fourier series are fit to the image data based on time of each image acquisition relative to the phase of the cardiac and respiratory cycles, monitored using a photoplethysmograph and pneumatic belt, respectively. The RETROICOR method is demonstrated using resting-state experiments on three subjects and compared with the k-space method. The method is found to perform well for both respiration- and cardiac-induced noise without imposing spatial filtering on the correction. Magn Reson Med 44:162-167, 2000., (Copyright 2000 Wiley-Liss, Inc.)

We report acute and follow-up diffusion- and perfusion-weighted MRI (DWI, PWI) findings in a patient with a prolonged reversible ischaemic neurological deficit. PWI 12 h after the patient was last seen to be without symptoms revealed a large perfusion deficit in the left posterior MCA territory with a relatively inconspicuous and much smaller abnormality on DWI. Follow-up showed resolution of abnormalities on both DWI and PWI, and conventional MRI was normal, apart from a very slight abnormality, visible only on FLAIR images, at the centre of the initially DWI-positive region. These findings demonstrate the utility of PWI when be used in combination with DWI to investigate the pathophysiology of transient ischemic syndromes.

Background and Purpose: Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) have been used increasingly in recent years to evaluate acute stroke in the emergency setting. In the present study, we compared DWI and PWI findings in acute stroke patients with and without severe extracranial internal carotid artery (ICA) disease., Methods: Twenty-seven patients with nonlacunar ischemic stroke were selected for this analysis. DWI, PWI, and conventional MRI were performed in all patients within 24 hours of symptom onset and after 1 week. To exclude patients with partial or complete reperfusion, we included only patients with a PWI deficit larger than the DWI lesion. Severe ICA disease (>70% stenosis) was present unilaterally in 9 and bilaterally in 2 patients. Acute DWI lesion volume, the size of the acute PWI/DWI mismatch, and final infarct size (on T2-weighted images) were determined., Results: The PWI/DWI mismatch was significantly larger in patients with severe ICA disease than in patients without extracranial carotid stenosis, both when time-to-peak and mean transit time maps (P<0.01) were used to calculate the mismatch. Quantitative analysis of the time-to-peak delay in the mismatch indicated that a relatively smaller fraction of the total mismatch was critically ischemic in patients with carotid stenosis than in those without. Average lesion volume increased less in the stenosis group (P=0.14), despite the larger PWI/DWI mismatch, and final infarct size was smaller in the stenosis group (P<0.05). In the 2 patients with bilateral ICA disease, variable hemodynamic involvement of the contralateral hemisphere was found in addition to the ipsilateral PWI deficit., Conclusions: In most acute stroke patients with severe ICA stenosis, a considerably smaller fraction of the total PWI/DWI mismatch is at risk than in patients without carotid disease.

Objective: To determine if coronary artery bypass graft (CABG) surgery without cardiopulmonary bypass (CPB) avoids the brain swelling known to occur after CPB, to quantify these brain water compartment changes, and to identify the water shifts as due to intracellular or extracellular water., Design: Prospective, controlled, and blinded., Setting: Cardiac surgical unit in a university teaching hospital., Subjects: Patients scheduled for CABG who were assigned to conventional (n = 10) or off-pump (n = 7) surgery according to their coronary anatomy., Interventions: Magnetic resonance imaging (MRI) examinations were performed 1 day before surgery and 1 hour and 1 week after CABG surgery., Main Outcome Measures: Extracellular and intracellular water homeostasis was described quantitatively by calculating the averaged apparent diffusion coefficient of brain water using diffusion-weighted MRI. Blinded visual ordering of the images from the three examinations was performed according to brain size using conventional MRI., Results: The average diffusion coefficient of brain water increased 4.7%+/-1.5% immediately after CABG with CPB and normalized after 1 week but did not change after CABG without CPB. No focal ischemic changes were seen in either group, and no gross neurologic deficits were observed. Visual analysis showed consistent brain swelling after CPB and variable changes in those operated without CPB., Conclusion: Changes consistent with increased extracellular brain water seen after CABG with CPB were not observed in patients undergoing CABG without CPB. The clinical significance of brain water changes and increased brain water content after surgery with CPB remains undefined.

In this study an arterial spin-tagging technique based on flow-sensitive alternating inversion recovery (FAIR) with single-shot spiral data acquisition was used to study how the basal cerebral blood flow (CBF) elevated by breath holding affects the regional cerebral blood flow (rCBF) response to focal brain activation in the motor cortex. Six subjects were examined using three types of activation studies. These were (a) bilateral finger tapping paced at 4 Hz under normal breathing, (b) repeated expiration breath holding of 30 s, and (c) simultaneous breath holding and finger tapping. It was found that in five of six subjects the prevailing CBF level adjusted by breath challenge and the increase in rCBF in motor cortex associated with bilateral finger tapping were completely additive. This finding from FAIR-based functional magnetic resonance imaging is in accordance with that reported from published positron emission tomography studies. The results indicate that in the majority of the subjects examined the regulatory mechanisms for vasodilatory reaction to CO(2) and rCBF response to neural activation in motor cortex region are independent., (Copyright 1999 Academic Press.)

Using functional magnetic resonance imaging techniques CBF and oxygenation changes were measured during sustained checkerboard stimulation in 38 right-handed healthy volunteers (18 men and 20 women). The average blood oxygenation level dependent (BOLD) contrast technique signal intensity change was 1.67 +/- 0.6% in the group of male volunteers and 2.15 +/- 0.6% in the group of female volunteers (P < .05). Baseline regional CBF (rCBF) values in activated gray matter areas within the visual cortex were 57 +/- 10 mL x 100 g(-1) x min(-1) in women and 50 +/- 12 mL x 100 g(-1) x min(-1) in men, respectively (P = .09). Despite a broad overlap between both groups the rCBF increase was significantly higher in women compared to men (33 +/- 5 mL x 100 g(-1) x min(-1) versus 28 +/- 4 mL x 100 g(-1) x min(-1), P < .01). The increase of rCBF was not correlated with the baseline rCBF (mL x 100 g(-1) x min(-1)) (r(s) = 0.01, P = .9). Moreover, changes of rCBF were not correlated with changes in BOLD signal intensities (r(s) = 0.1, P = .7). Enhanced rCBF response in women during visual stimulation could be related to gender differences in visual physiology or may reflect gender differences in the vascular response to focal neuronal activation. Gender differences must be considered when interpreting the results of functional magnetic resonance imaging studies.

Background and Purpose: In the past, functional MR imaging techniques have been used successfully to determine cerebrovascular reactivity (CVR) to various stimuli, complementing the arsenal of functional brain investigations feasible with MR imaging. While previous studies have focused on blood oxygenation changes under vasodilatory stress, the aim of this study was to assess regional cerebral blood flow (rCBF) changes during breath-holding by using a flow-sensitive alternating inversion recovery (FAIR) imaging technique., Methods: In six healthy volunteers, FAIR images were acquired during alternating periods of breath-holding and breathing at 40-second intervals after inspiration and at 30-second intervals after expiration, for a total dynamic scanning time of 10 minutes. To quantify the rCBF changes, we obtained 2.5-minute baseline samples during normal breathing., Results: Repeated challenges of breath-holding induced an overall rise in rCBF. In general, rCBF changes were greatest in gray matter and were insignificant in white matter. Using the mean values of the baseline images collected before breath-holding to calculate the rCBF changes, we found that quantitative analysis yielded an rCBF increase of 47% to 87% after breath-holding. The rCBF changes clearly depended on the breath-holding duration and technique; however, for one given breath-holding paradigm the results showed relatively small interindividual variability., Conclusion: rCBF changes during a simple vascular challenge can be detected and quantified by means of functional MR imaging at 1.5 T. Noninvasive assessment of CVR could become a useful clinical tool to identify persons with impaired CVR.

Functional magnetic resonance imaging (fMRI) based on multiple-echo T(2)* mapping has attracted much attention recently. The contrasts in the parametric T(2)* maps are usually too low to allow direct image registration. In this study, an image registration strategy has been proposed for single-shot multi-echo data sets acquired for dynamic T(2)* mapping. We performed image registration of the T(2)*-weighted images before the calculation of the T(2)* parameter maps using two different strategies. One is to perform separate image registration on each echo and the other is to use the same motion correction parameters extracted from the second echo for all the data. Both strategies increase the number of activated voxels and reduce the effective noise level. The results also indicate that, for a single-shot dual-echo image data set, it is slightly preferable to use the second echo for direct image registration and then apply the same motion correction parameters to the first echo images. J. Magn. Reson Imaging 1999;10:154-158., (Copyright 1999 Wiley-Liss, Inc.)

Using fMRI, the relationship between regional cerebral blood flow (rCBF) changes during visual stimulation and the prevailing baseline global and regional flow levels was evaluated in 22 volunteers. The absolute increase in rCBF was not correlated with baseline rCBF values (r = 0.01, p = 0.8); however, the percentage change in rCBF showed a negative correlation (r=-0.78, p<0.001). Both absolute and relative changes in rCBF were independent of baseline global CBF values. These results indicate that caution should be exercised when comparing relative flow changes during focal brain activation, especially in functional neuroimaging studies dealing with altered baseline flow values.

Various spatial autocorrelation statistics have been widely used both in theoretical population genetics and to study the spatial distribution of diploid genotypes in many plant and animal populations. However, previous simulation studies have considered only diallelic loci. In this paper, we use a large number of space-time simulations to characterize for the first time the parametric and statistical values of Moran's I-statistics for converted individual genotypes as well as for join-count statistics. A wide range of levels of dispersal and numbers of alleles and allele frequencies are modelled and the results reveal the different general effects of each of these factors on these statistics. We also examine the range of appropriate sampling designs and sizes for which predicted values can be interpolated for specific sampling schemes for any given population genetic field survey. Numbers of alleles and allele frequencies each affect some statistics but not others. The results indicate generally low standard deviations. The results also develop precise and efficient methods of estimating gene dispersal, based on the various autocorrelation measures of standing spatial patterns of genetic variation within populations. The results also extend these methods to loci with multiple alleles, typical of those studied through modern molecular methods.

BOLD (blood oxygenation level-dependent) and FAIR (flow-sensitive alternating inversion recovery) imaging techniques were used to investigate the oxygenation and hemodynamic responses of human brain during repeated challenges of breath holding and prolonged single breath holding. The effects of different breathing techniques on BOLD and FAIR image contrasts were carefully examined. With a periodic breath-holding paradigm of 30 s, global changes in gray matter were observable both in T*2-weighted and FAIR images. T*2-weighted images showed 1-4% relative signal intensity increases, while FAIR images demonstrated relative cerebral blood flow (CBF) increase up to 30-70%. The activated pixels depicted in FAIR images were about three times less than those seen in T*2-weighted images. With prolonged breath holding, it was observed that signal intensities in T*2-weighted and FAIR images were dependent on the breathing techniques used. Breath holding after expiration gave rise to immediate signal intensity increases in T*2-weighted and FAIR images, whereas breath holding performed after deep inspiration signals showed a biphasic change both in flow and T*2-weighted. T*2-weighted and FAIR signals showed a transient decrease before rising above the baseline level., (Copyright 1999 Academic Press.)

Diffusion-weighted MRI based on single-shot echo planar imaging (EPI) has been established as a useful tool to study acute cerebral ischemia. However, EPI is prone to spatial distortion and ghosting artifacts. In this study, a pulse sequence for diffusion-weighted imaging (DWI) based on a single-shot spiral readout is presented. Using this technique, multislice apparent diffusion coefficient (ADC) mapping can be performed in an interleaved fashion with the same temporal resolution as EPI. Other advantages associated with ADC mapping by the single-shot spiral method include minimal ghosting artifacts, reduced spatial distortion, and capability to scan in arbitrary planes. This technique has been successfully tested in five normal volunteers and three stroke patients. It has been demonstrated that the single-shot spiral technique is capable of producing high quality DWI and ADC trace maps (128 x 128) in the axial, sagittal, and coronal planes, which facilitate clinical diagnosis.

The aim of the study was to assess the relative number of bone trabeculae in different orientations by using magnetic inhomogeneity measurements by MR imaging. Twelve defatted human vertebrae (L2-L4) were studied by MR imaging and CT. In the MR measurements the reversible transaxial decay rate, R2', was determined using the GESFIDE sequence. The relative contribution to R2' of bone trabeculae oriented along the x (R2'x), y (R2'y) and z (R2'y) axes was assessed, by rotation of the specimen in the magnetic field. The results were validated by CT measurements of trabecular structure at a resolution of 0.2 x 0.2 x 1 mm. using custom-made software. R2' ranged from 4.9 to 32 s-1. After separation, theoretical R2'x ranged from 2.3 to 10.7 s-1, R2'y ranged from 2.6 to 14.0 s-1 and R2'z ranged from 4.7 to 17.9 s-1. The number of bone trabeculae per millimeter identified in axial CT images ranged from 0.15 to 0.38 and from 0.039 to 0.22 per millimeter in sagittal images. The difference between axial and sagittal CT images was statistically significant and due to anisotropic voxels. The correlation between R2' and the number of bone trabeculae per millimeter was statistically significant (r = 0.83, p < 0.001 for x orientation: r = 0.63 for y orientation, and r = 0.59 for z orientation, p < 0.05 for both). The relative amount of bone trabeculae in different orientations can be assessed in vitro using R2' measurements.

Background and Purpose: Recently, noninvasive MRI methods have been developed that are now capable of detecting and mapping regional hemodynamic responses to various stress tests, which involve the use of vasoactive substances such as acetazolamide or inhalation of carbon dioxide. The aim of this study was to assess regional cerebral blood oxygenation changes during breath holding at 1.5 T., Methods: In 6 healthy volunteers, T2*-weighted gradient echo images were acquired for a total dynamic scanning time of 10 minutes during alternating periods of breath holding and normal breathing at 40-second intervals after inspiration, at 30-second intervals after expiration, and at 18 seconds after expiration. To quantify the relative signal changes, 2.5-minute baseline image sampling with normal breathing was carried out., Results: Repeated challenges of breath holding of various durations induced an overall rise in blood oxygen level-dependent (BOLD) signal intensities. In general, BOLD signal intensity increases were greatest in gray matter and nonsignificant in white matter. Depending on the breath-holding duration and techniques, BOLD signal intensity increases of all activated pixels varied from 0.8% to 3.5%., Conclusions: The present study demonstrates that cerebral blood oxygenation changes during breath holding can be detected by means of fMRI at 1.5 T. The breath-holding test, a short and noninvasive method to study cerebral hemodynamics with fMRI, could become a useful alternative to the acetazolamide or CO2 test.

Diffusion-weighted MR imaging has been used in studies on experimental animal models and on patients with acute cerebral ischemia. Compared with CT and conventional MR techniques, diffusion-weighted imaging can provide earlier and more precise detection of the location and the extent of an ischemic lesion during the critical first few hours after the onset of stroke. Quantitative apparent diffusion coefficient (ADC) mapping of the brain water can also be carried out by recording a series of diffusion-weighted images with different amplitudes of the displacement encoding gradients. ADC maps can provide important information about the extra- and intracellular water homeostasis. ADC reduction of the tissue water is one of the early signals of the pathophysiological cascade resulting from ischemic tissue injury. Diffusion MR imaging has become a valuable tool in stroke research. It may also prove a valuable tool in monitoring the efficiency of therapeutic effects in stroke patients. It is our intention to provide an overview of the recent development in this area with emphasis on the diffusion-weighted MR techniques, and to discuss the possible underlying biophysical mechanisms responsible for the contrast of diffusion-weighted imaging.

Spatial autocorrelation statistics have been studied in theoretical population genetic models and widely used in experimental studies of spatial structure in many plant and animal populations. However, the statistical properties of spatial autocorrelation statistics have remained uncharacterized. Little is known about how values of spatial autocorrelation statistics in population samples depend on the level of dispersal and scheme of sampling. In this paper, we characterize the statistical properties of join-count spatial autocorrelation statistics for population genetic surveys under various conditions of dispersal and sampling. The results indicate generally high statistical power. These results can provide a method to estimate gene dispersal based on standing spatial patterns of genetic variation observed within populations., (© 1997 The Society for the Study of Evolution.)

A time-averaged method to obtain quantitative measurements in turbulent flow by phase flow encoding NMR imaging is introduced. With this method time-averaged velocity profiles and turbulence intensities can be determined. Time-averaged velocity profiles for pipe flow of water driven by a constant pressure gradient at Reynolds numbers from 1200 to 9400 were visualized. A precise correlation between the pixel intensity of the time-averaged NMR flow image and the local turbulence intensity of the flow is derived. The measured turbulence intensities are in agreement with published data obtained using other experimental methods.

Serum amylase level was determined in 129 cases (225 episodes) of chronic respiratory failure at acute exacerbation and in 59 cases (62 episodes) of pneumonia without respiratory failure as control. Cases with accompanying diseases, such as acute pancreatitis, parotiditis, ileus and renal dysfunction, which were expected to develop hyperamylasemia were excluded. The 225 episodes were divided according to the causes of acute exacerbation into 4 groups: pneumonia, bronchitis, right heart failure without infection, and others (e. g. hemoptysis). Hyperamylasemia (greater than 400 S-U) was observed in groups of pneumonia (15/40 = 35.5%) and bronchitis (12/95 = 12.6%), respectively but not in those of right heart failure without infection (0/73 = 0%) and other causes (0/17 = 0%). As a result, hyperamylasemia was found only under conditions of inflammation of lung parenchyma and bronchi with acute exacerbation of respiratory failure. On the other hand no hyperamylasemia was observed in 62 episodes of pneumonia alone without respiratory failure. It was concluded that both respiratory tract infection and acute respiratory failure are necessary factors for development of hyperamylasemia originating from lung or bronchi.