Linking watershed and eutrophication modelling for the Shihmen Reservoir, Taiwan

The Shihmen Reservoir, located in northern Taiwan, features the second storage volume of impoundments on the island. The watershed of the Shihmen Reservoir has been subjected to serious pollutants due to anthropogenic interference. This study applies a watershed model, BASINS, to simulate the flow and nutrients loads from the watershed. BASINS then drives the CE-QUAL-W2 model for water quality predictions in the reservoir. The watershed modelling results are compared with field data. They reveal that significant nutrient loads were generated from the watershed during storms. The model calibration and verification were achieved with water surface elevation, temperature, and water quality constituents including nutrients, dissolved oxygen, and chlorophyll a in the reservoir using the eutrophication model.

Modelling the epidemiology of Verocytotoxin-producing Escherichia coli serogroups in young calves

We investigate the epidemiology of 12 Verocytotoxin-producing Escherichia coli (VTEC) serogroups observed in a calf cohort on a Scottish beef farm. Fitting mathematical models to the observed time-course of infections reveals that there is significant calf-to-calf transmission of VTEC. Our models suggest that 40% of all detected infections are from calf-to-calf transmission and 60% from other sources. Variation in the rates at which infected animals recover from infection by different VTEC serogroups appears to be important. Two thirds of the observed VTEC serogroups are lost from infected calves within 1 day of infection, while the rest persist for more than 3 days. Our study has demonstrated that VTEC are transmissible between calves and are typically lost from infected animals in less than 1 week. We suggest that future field studies may wish to adopt a tighter sampling frame in order to detect all circulating VTEC serogroups in similar animal populations.

Critical review on non-operative management of adolescent idiopathic scoliosis

There are a number of different non-operative interventions which aim to control moderate adolescent idiopathic scoliosis (AIS) from progression. Clinicians may find difficulties in the selection of appropriate interventions for AIS. A comprehensive literature review was carried out to study all contemporary non-operative interventions, it was noted that rigid spinal orthoses apparently give more curve control; however, it would compromise the patient's quality of life via those inevitable factors--physical constraint, poor acceptance and psychological disturbance. There is a trend to develop more effective, acceptable and user-friendly interventions. Under such an aspiration, the theories and clinical evidence of different interventions should be developed along the clinical pathway of early intervention with reliable indicators/predictors, patient's active participation, dynamic control mechanism, holistic psychological and psychosocial considerations, and effective and long-lasting outcome.

Therapeutic effect of pirenzepine for clozapine-induced hypersalivation: a randomized, double-blind, placebo-controlled, cross-over study

The objective of this study was to investigate the efficacy of pirenzepine in the treatment of clozapine-induced hypersalivation. Pirenzepine is reported to counteract hypersalivation by its selective antagonistic activity on the M4-muscarinic receptor, which is stimulated by clozapine. Twenty patients with clozapine-induced hypersalivation underwent a random-order, double-blind, placebo-controlled, cross-over trial which lasted 8 weeks each for the pirenzepine and placebo investigations, with a 4-week washout period in between. The severity of hypersalivation was assessed using an objective measure: saliva production monitored through the diameter of wetted surface on tissue paper placed over the patient's pillow. Our study showed that pirenzepine had no significant therapeutic effect on hypersalivation compared with placebo, suggesting that hypersalivation induced by clozapine might have a neurobiological basis other than the M4-muscarinic receptor.

Detection of circulating CEA molecules in human sera and leukopheresis of peripheral blood stem cells with E. coli expressed bispecific CEAScFv-streptavidin fusion protein-based immuno-PCR technique

In this study, a method called bispecific CEAScFv-streptavidin fusion protein-based immuno-PCR technique will be tested experimentally. The application of the bispecific fusion protein-based immuno-PCR technique has the significant advantage that it can be readily applied in the clinical setting, as well as tested as a potential screening tool in high-risk populations of certain types of cancer.

Functional magnetic resonance imaging of working memory impairment after traumatic brain injury

OBJECTIVES

To examine patterns of brain activation while performing a working memory task in persons with moderate to severe traumatic brain injury (TBI) and healthy controls. It is well established that working memory is an area of cognition that is especially vulnerable to disruption after TBI. Although much has been learned about the system of cerebral representation of working memory in healthy people, little is known about how this system is disrupted by TBI.

METHODS

Functional magnetic resonance imaging (fMRI) was used to assess brain activation during a working memory task (a modified version of the paced auditory serial addition test) in nine patients with TBI and seven healthy controls.

RESULTS

Patients with TBI were able to perform the task, but made significantly more errors than healthy controls. Cerebral activation in both groups was found in similar regions of the frontal, parietal, and temporal lobes, and resembled patterns of activation found in previous neuroimaging studies of working memory in healthy persons. However, compared with the healthy controls, the TBI group displayed a pattern of cerebral activation that was more regionally dispersed and more lateralised to the right hemisphere. Differences in lateralisation were particularly evident in the frontal lobes.

CONCLUSIONS

Impairment of working memory in TBI seems to be associated with alterations in functional cerebral activity.

Serotonin 6 receptor polymorphism in schizophrenia: frequency, age at onset and cognitive function

The relative abundance of serotonin 6 receptor (5HT6) in some limbic regions and the high affinity of some antipsychotics for 5HT6 suggest that the 5HT6 gene might play a role in the pathogenesis of schizophrenic disorders. A recent study reported an association between a C267T polymorphism of the 5HT6 gene and schizophrenia. In order to test whether the 5HT6 gene plays a role in the pathogenesis of schizophrenic disorders, patients (n = 148) and control subjects (n = 160) were genotyped for 5HT6. We also investigated the relationship between genotypes and patients' age at onset and cognitive function in schizophrenic patients. Cognitive function in the patients was evaluated by the Mini-Mental State Examination (MMSE). The results demonstrated no significant differences in genotype or allele frequencies between controls and patients. In the patient group, age at onset and MMSE score did not differ significantly among the three 5HT6 genotpyes. The results of this study suggest that the 5HT6 C267T polymorphism plays no major role in susceptibility to the development of schizophrenia and is not related to cognitive impairment or age at onset in schizophrenic patients. Further studies of the relation between 5HT6 polymorphism and the symptoms and the therapeutic response in schizophrenic patients may help to elucidate the role of 5HT6 in the pathogenesis of schizophrenia.

A modeling study of water quality in main channel and estuarine wetland

A simple computation framework is applied to include estuarine wetland and their interaction with main channels in estuarine modeling. The concept and the model implementation of the scheme are explained using a vertical two-dimensional model of estuarine hydrodynamics and water quality. The model was applied to the Tanshui River estuary and Kuan-Du wetland. The model is calibrated and verified by the available measured data. Simulations are also conducted for various upstream freshwater discharges to predict water quality in the main channel and estuarine wetland. The results show that the inclusion of estuarine wetland in a water-quality model not only provides a framework for computing water-quality conditions but also accounts for the interaction between wetland and main channel. The model provides a useful tool for environmental planning, protection and proposed wetland restoration works.

Testosterone regulates alpha-synuclein mRNA in the avian song system

Alpha-synuclein is a small, highly conserved protein in vertebrates that has been linked to several neurodegenerative diseases. The avian song control system is one of the model systems in which the protein was independently discovered. Alpha-synuclein is dynamically regulated in the song system during song learning, a process in which sex steroids play a central role. We compared alpha-synuclein mRNA expression in the brains of 12 adult male chipping sparrows (Spizella passerina) treated with either testosterone or blank s.c. implants. We saw pronounced upregulation of alpha-synuclein mRNA in, as well as an increase in the volume of, the song control nucleus area X in response to exogenous testosterone. To our knowledge this is the first report of steroid regulation of synuclein gene expression in any model system.

Different mechanisms of radiation-induced loss of heterozygosity in two human lymphoid cell lines from a single donor

Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis combined with microsatellite marker analysis showed that the increase in TK1 mutagenesis in WTK1 cells could be attributed, in part, to mitotic recombination. The microsatellite marker analysis over a 64-cM region on chromosome 17q indicated that the recombinational events could initiate at different positions between the TK1 locus and the centromere. Virtually all of the recombinational LOH events extended beyond the TK1 locus to the most telomeric marker. In general, longer LOH tracts were observed in mutants from WTK1 cells than in mutants from TK6 cells. Taken together, the results demonstrate that the incidence of radi-ation-induced mutations is dependent on the genetic background of the cell at risk, on the locus examined, and on the mechanisms for mutation available at the locus of interest.

The effect of brain tumors on BOLD functional MR imaging activation in the adjacent motor cortex: implications for image-guided neurosurgery

BACKGROUND AND PURPOSE

Functional MR (fMR) imaging data coregistered to a neurosurgical navigation system have been proposed as guides for the resection of brain tumor in or adjacent to eloquent cortices. The purpose of this study was to compare data obtained from the side of the brain affected by tumor with the contralateral side and to determine if there are physiological limitations of fMR imaging in accurately determining the location of the primary motor cortex.

METHODS

Ten patients with tumors in or directly adjacent to the motor cortex were studied with fMR imaging (finger-tapping paradigm). fMR imaging data were analyzed using multiple R values. These data were coregistered to a real-time intraoperative neurosurgical navigation system.

RESULTS

Significant variability of motor cortex activation patterns was noted among individual patients. The activation volumes on the side of the tumor were significantly smaller compared with the contralateral side for all tumors not previously resected (0.66+/-0.47). This was most pronounced in glioblastomas (0.27+/-0.21). We propose that these differences were caused by a loss of autoregulation in the tumor vasculature of glioblastomas and venous effects.

CONCLUSION

Notwithstanding the differences noted, the motor cortex was identified successfully in all patients. This was confirmed by intraoperative physiological identification of the motor cortex and a lack of postoperative neurologic deficit.

Identification of the corticospinal tracts achieved using blood-oxygen-level-dependent and diffusion functional MR imaging in patients with brain tumors

Diffusion-weighted MR imaging was used to delineate the corticospinal tract (CST) successfully and to depict its relationship to adjacent brain tumors. The CST was defined by a method by which it seems possible to delimit the distance from the CST to the main tumor mass and to show displacement and infiltration of the tract by the neoplasia. This information cannot be gathered from routine anatomic MR imaging.

Design and optimization of a diode-pumped fiber-coupled yb:er glass waveguide laser

An adaptive simulated annealing optimization algorithm is used to derive laser rate equation and waveguiding models with which the best design for a diode-pumped fiber-coupled, Yb:Er glass waveguide laser can be determined. Material parameters that correspond to commercially available laser-glass and diode-pump sources are used in this study. Given a continuous-wave 300-mW pump at 977 nm, approximately 48 mW of power at 1540 nm can be coupled into the LP(01) mode of an optical fiber. Fabrication and alignment tolerance analyses are presented.

Functional magnetic resonance imaging and radiosurgical dose planning

OBJECTIVE

To assess the effect of functional magnetic resonance imaging (fMRI) on stereotactic radiosurgical (SRS) dose planning.

METHODS

Patients included those undergoing SRS whose lesions were in or near areas that could be identified with fMRI. After processing, an fMR scan was registered to the anatomic scan, and this dataset was registered to a stereotactic CT scan. The imaged functional areas were contoured along with standard anatomical targets. Dose planning was done at first with the functional volumes rendered invisible; the plans were then adjusted as needed using the functional targets. Doses were measured using a dose-volume histogram tool.

RESULTS

SRS was performed in 12 patients, 1 of whom also underwent SRT. Functional volumes studied included motor cortex in 8 patients, visual in 6 and language in 3; a total of 33 functional targets were imaged. Prescription doses ranged from 12 to 22.5 Gy (mean 19.5 Gy), and the maximum dose to functional volumes from 8 cGy to 18.5 Gy (mean 2.9 Gy). In 6 patients, arc adjustment using functional targets yielded a >50% reduction in dose to at least one functional volume; in all patients, the dose reduction to 50 and 75% of functional volumes averaged 4% (12 cGy) and 13% (30 cGy), respectively, while the reduction of maximal dose averaged 24% (50 cGy).

CONCLUSIONS

fMRI can be used in SRS to reduce irradiation of eloquent brain using standard prescription doses. Appropriate arc adjustment may allow for escalation of the dose to the targeted lesion.

Functional magnetic resonance image-guided surgery of tumors in or near the primary visual cortex

OBJECTIVE

To assess the accuracy of functional magnetic resonance imaging (fMRI) of the primary visual cortex in patients undergoing surgery for tumors in the occipital lobe.

METHODS

Two patients with nondominant occipital lobe tumors were studied, one with a solitary lung metastasis and another with radiation necrosis after radiosurgery for a low-grade astrocytoma. At surgery, visual evoked potentials (VEPs) were stimulated using Light-emitting-diode goggles and recorded using cortical grids placed immediately after brain exposure. The location of the peak VEP was compared to that predicted by the registered functional scan.

RESULTS

In each case, the epicenter of visual activation as represented on the registered fMRI corresponded to the site of peak VEP recording. Prediction error for the visual cortex, measured in patient 1, was 1.0 mm. Visual confirmation showed the registration in the second patient to be accurate as well.

CONCLUSION

As previously demonstrated for sensorimotor fMRI, visual fMRI accurately predicts the location of the primary visual cortex. Additional confirmation is expected with more clinical experience.

The effect of brain tumors on BOLD functional MR imaging activation in the adjacent motor cortex: implications for image-guided neurosurgery

BACKGROUND AND PURPOSE

Functional MR (fMR) imaging data coregistered to a neurosurgical navigation system have been proposed as guides for the resection of brain tumor in or adjacent to eloquent cortices. The purpose of this study was to compare data obtained from the side of the brain affected by tumor with the contralateral side and to determine if there are physiological limitations of fMR imaging in accurately determining the location of the primary motor cortex.

METHODS

Ten patients with tumors in or directly adjacent to the motor cortex were studied with fMR imaging (finger-tapping paradigm). fMR imaging data were analyzed using multiple R values. These data were coregistered to a real-time intraoperative neurosurgical navigation system.

RESULTS

Significant variability of motor cortex activation patterns was noted among individual patients. The activation volumes on the side of the tumor were significantly smaller compared with the contralateral side for all tumors not previously resected (0.66+/-0.47). This was most pronounced in glioblastomas (0.27+/-0.21). We propose that these differences were caused by a loss of autoregulation in the tumor vasculature of glioblastomas and venous effects.

CONCLUSION

Notwithstanding the differences noted, the motor cortex was identified successfully in all patients. This was confirmed by intraoperative physiological identification of the motor cortex and a lack of postoperative neurologic deficit.

Directional correlation in direct and sequential double ionization of model atoms

We discuss directional dependence in the time development of spatial wavefunctions, which includes jet formation, for two-electron model atoms exposed to intense laser fields. Two competing scenarios for double ionization are evident: (1) both electrons emerge simultaneously from the core region and on the same side of the nucleus, and (2) the electrons detach on opposite sides but not simultaneously. The importance of the electron-electron repulsion contribution to the competing processes is investigated for various laser intensities.

Functional magnetic resonance imaging aided radiation treatment planning

Functional MRI (magnetic resonance imaging) allows one to noninvasively identify various eloquent cortices in the brain. The integration of cortical activation information into radiosurgical treatment planning may provide an alternative to prevent or minimize radiation damage to eloquent cortex. A novel approach of directly integrating the fMRI (functional magnetic resonance imaging) brain map into treatment planning is proposed. Three brain tumor patients have been studied using this method with motor and/or visual paradigms. Brain activation was demonstrated in eloquent cortex at the precentral gyrus (motor area) and medial occipital lobe (visual area). The activation maps were transferred to a treatment planning workstation, (XKnife), and 3D (three-dimensional) activation maps were generated and co-registered to a 3D CT (computed tomography) anatomical data set, which provided the calibration localizer, for treatment planning. Radiosurgery was designed based on both functional and structural information by the medical team consisting of a radiation oncologist, a neurosurgeon and a physicist. The average maximum dose for the tumor was 2113 cGy. The average maximum dose for tissue surrounding the tumor was 1600 cGy. The average dose with fMRI information to the eloquent cortex was 163.4 cGy over three patients, while without fMRI information it was 240.5 cGy. The average percentage dose reduction over three patients is 32%. The results suggest that using this method can reduce the dose to the eloquent cortex. This approach provides the physician with additional information for treatment planning and may spare the patient unnecessary radiation exposure to adjacent eloquent cortices.

Does a herniated nucleus pulposus contribute significantly to a decrease in height of the intervertebral disc? Quantitative volumetric MRI

A lumbar intervertebral disc with a herniated nucleus pulposus (HNP) often exhibits a decrease in the height of the intervertebral space. Our purpose was to ascertain whether the loss of volume of an HNP is sufficient to cause a perceptible decrease in the height of the intervertebral space. MRI of 44 patients with 51 HNPs were reviewed. The volumes of the herniated material and of the intervertebral discs were calculated for every level from L1-2 to L5-S1. The average volume of the HNP was 503 +/- 301 mm3. The average volumes of all 220 intervertebral discs and of the 127 normal-appearing discs were 14,442 +/- 4200 mm3 and 17,476 +/- 2885 mm3 respectively. The average volume of the HNP represented 3.5% of the parent disc. An average HNP caused a decrease in intervertebral space height of 0.35 mm (0.56 pixels). Therefore, the loss of the volume of the HNP does not cause a significant decrease in the intervertebral space height. The average calculated decrease in the disc height is less than that reported in normal diurnal variation.

Invasion sequence affects predator-prey dynamics in a multi-species interaction

Ecologists seek to understand the rules that govern the assembly, coexistence and persistence of communities of interacting species. There is, however, a variety of sequences in which a multi-species community can be assembled--unlike more familiar one- and two-species systems. Ecological systems can exhibit contrasting dynamics depending on initial conditions, but studies have been focused on simple communities initiated at different densities, not on multi-species communities constructed in different sequences. Investigations of permanence and convergence in ecological communities have been concerned with the flux of whole species (presence or absence) but have not addressed the central issues concerning the dynamics exhibited by individual species in particular interactions. Here we examine data for replicated three-species systems and demonstrate that the dynamic trajectories of both a predator and its prey within the system are determined by the sequence in which it is constructed, and that for one construction-sequence alternative dynamic patterns are possible.

Positioning of vagal nerve stimulators: technical note

BACKGROUND

Vagal nerve stimulation has become an important treatment for patients with intractable seizure disorders. Many of these patients will require magnetic resonance imaging (MRIs) of the brain after the stimulator has been implanted to monitor underlying neurologic conditions. Functional MRI (fMRI) is also being used in the evaluation of epilepsy. With the current recommended implant techniques the magnetic field of the MRI will deactivate the pulse generator while the patient is in the supine position for the scan. A simple change in positioning of the pulse generator will help to avoid deactivating the device during an MRI. This will avoid exposing the patient to lengthy time periods with a deactivated stimulator and also allow for the performance of fMRIs and any other MRI scans needed to monitor underlying neurologic conditions.

METHODS

A working model of the NeuroCybernetic Prosthesis (NCP) pulse generator was assessed with an oscilloscope and LED light connected to it that related activation of the generator while in the MRI. This simulation was performed with the device alone, in multiple positions. Then patients with implanted devices who could personally confirm the activation of their stimulators were also studied.

RESULTS

A pulse generator placed with the electrode inputs parallel to the long axis of the body was not deactivated by the magnetic field of the MRI when the patient was in the supine position.

CONCLUSION

Changing the implant position of a vagal nerve stimulator pulse generator will help to prevent deactivation of the device while in the MRI, allowing for the performance of fMRIs while not exposing the patient to lengthy time periods with a deactivated vagal nerve stimulator.

Tuberculous aneurysm of the abdominal aorta: endovascular repair using stent grafts in two cases

Tuberculous aneurysm of the aorta is exceedingly rare. To date, the standard therapy for mycotic aneurysm of the abdominal aorta has been surgery involving in-situ graft placement or extra-anatomic bypass surgery followed by effective anti-tuberculous medication. Only recently has the use of a stent graft in the treatment of tuberculous aortic aneurysm been described in the literature. We report two cases in which a tuberculous aneurysm of the abdominal aorta was successfully repaired using endovascular stent grafts. One case involved is a 42-year-old woman with a large suprarenal abdominal aortic aneurysm and a right psoas abscess, and the other, a 41-year-old man in whom an abdominal aortic aneurysm ruptured during surgical drainage of a psoas abscess.

Optimization of gray/white matter contrast with fast inversion recovery for myelin suppression: a comparison of fast spin-echo and echo-planar MR imaging sequences

We compared two MR imaging sequences, fast inversion recovery for myelin suppression (FIRMS) and echo-planar FIRMS (EP-FIRMS), for depicting gray/white matter contrast. In 18 patients, the frequency bandwidth (BW) was optimized for each sequence; in nine patients, the BW was held constant. In the BW-optimized group, the mean contrast-to-noise ratio (C/N) was three times higher with the FIRMS sequence. In the BW-constant group, the mean C/N was 27% higher with the EP-FIRMS sequence; however, geometric distortion degraded the EP-FIRMS images excessively. For optimal gray/white contrast, FIRMS appears to be the superior pulse sequence.