VEGF Induces More Severe Cerebrovascular Dysplasia in Endoglin than in Alk1 Mice

Brain arteriovenous malformations (BAVMs) are an important cause of intracranial hemorrhage (ICH) in young adults. A small percent of BAVMs is due to hereditary hemorrhagic telangiectasia 1 and 2 (HHT1 and 2), which are caused by mutations in two genes involved in TGF-β signaling: endoglin (ENG) and activin-like kinase 1 (ALK1). The BAVM phenotype is an incomplete penetrant in HHT patients, and the mechanism is unknown. We tested the hypothesis that a "response-to-injury" triggers abnormal vascular (dysplasia) development, using Eng and Alk1 haploinsufficient mice. Adeno-associated virus (AAV) expressing vascular endothelial growth factor (VEGF) was used to mimic the injury conditions. VEGF overexpression caused a similar degree of angiogenesis in the brain of all groups, except that the cortex of Alk1(+/-) mice had a 33% higher capillary density than other groups. There were different levels of cerebrovascular dysplasia in haploinsufficient mice (Eng(+/)>Alk1(+/-)), which simulates the relative penetrance of BAVM in HHT patients (HHT1>HHT2). Few dysplastic capillaries were observed in AAV-LacZ-injected mice. Our data indicate that both angiogenic stimulation and genetic alteration are necessary for the development of dysplasia, suggesting that anti-angiogenic therapies might be adapted to slow the progression of the disease and decrease the risk of spontaneous ICH.

Dual-frequency pattern scheme for high-speed 3-D shape measurement

A novel dual-frequency pattern is developed which combines a high-frequency sinusoid component with a unit-frequency sinusoid component, where the high-frequency component is used to generate robust phase information, and the unit-frequency component is used to reduce phase unwrapping ambiguities. With our proposed pattern scheme, phase unwrapping can overcome the major shortcomings of conventional spatial phase unwrapping: phase jumping and discontinuities. Compared with conventional temporal phase unwrapped approaches, the proposed pattern scheme can achieve higher quality phase data using a less number of patterns. To process data in real time, we also propose and develop look-up table based fast and accurate algorithms for phase generation and 3-D reconstruction. Those fast algorithms can be applied to our pattern scheme as well as traditional phase measuring profilometry. For a 640 x 480 video stream, we can generate phase data at 1063.8 frames per second and full 3-D coordinate point clouds at 8.3 frames per second. These achievements are 25 and 10 times faster than previously reported studies.

Gamma model and its analysis for phase measuring profilometry

Phase measuring profilometry is a method of structured light illumination whose three-dimensional reconstructions are susceptible to error from nonunitary gamma in the associated optical devices. While the effects of this distortion diminish with an increasing number of employed phase-shifted patterns, gamma distortion may be unavoidable in real-time systems where the number of projected patterns is limited by the presence of target motion. A mathematical model is developed for predicting the effects of nonunitary gamma on phase measuring profilometry, while also introducing an accurate gamma calibration method and two strategies for minimizing gamma's effect on phase determination. These phase correction strategies include phase corrections with and without gamma calibration. With the reduction in noise, for three-step phase measuring profilometry, analysis of the root mean squared error of the corrected phase will show a 60x reduction in phase error when the proposed gamma calibration is performed versus 33x reduction without calibration.

Soluble endoglin modulates aberrant cerebral vascular remodeling

OBJECTIVE

Brain arteriovenous malformations (AVMs) are an important cause of neurological morbidity in young adults. The pathophysiology of these lesions is poorly understood. A soluble form of endoglin (sEng) has been shown to cause endothelial dysfunction and induce preeclampsia. We tested if sEng would be elevated in brain AVM tissues relative to epilepsy brain tissues, and also investigated whether sEng overexpression via gene transfer in the mouse brain would induce vascular dysplasia and associated changes in downstream signaling pathways.

METHODS

Expression levels of sEng in surgical specimens were determined by Western blot assay and enzyme-linked immunosorbent assay. Vascular dysplasia, levels of matrix metalloproteinase (MMP), and oxidative stress were determined by immunohistochemistry and gelatin zymography.

RESULTS

Brain AVMs (n = 33) had higher mean sEng levels (245 +/- 175 vs 100 +/- 60, % of control, p = 0.04) compared with controls (n = 8), as determined by Western blot. In contrast, membrane-bound Eng was not significantly different (108 +/- 79 vs 100 +/- 63, % of control, p = 0.95). sEng gene transduction in the mouse brain induced abnormal vascular structures. It also increased MMP activity by 490 +/- 30% (MMP-9) and 220 +/- 30% (MMP-2), and oxidants by 260 +/- 20% (4-hydroxy-2-nonenal) at 2 weeks after injection, suggesting that MMPs and oxidative radicals may mediate sEng-induced pathological vascular remodeling.

INTERPRETATION

The results suggest that elevated sEng may play a role in the generation of sporadic brain AVMs. Our findings may provide new targets for therapeutic intervention for patients with brain AVMs. Ann Neurol 2009;66:19-27.

Thermoelectric properties and efficiency measurements under large temperature differences

The maximum efficiency of a thermoelectric generator is determined by the material's dimensionless figure of merit ZT. Real thermoelectric material properties are highly temperature dependent and are often measured individually using multiple measurement tools on different samples. As a result, reported ZT values have large uncertainties. In this work we present an experimental technique that eliminates some of these uncertainties. We measure the Seebeck coefficient, electrical conductivity, and thermal conductivity of a single element or leg, as well as the conversion efficiency, under a large temperature difference of 2-160 degrees C. The advantages of this technique include (1) the thermoelectric leg is mounted only once and all measurements are in the same direction and (2) the measured properties are corroborated by efficiency measurements. The directly measured power and efficiency are compared to the values calculated from the measured properties and agree within 0.4% and 2%, respectively. The realistic testing conditions of this technique make it ideal for material characterization prior to implementation in a real thermoelectric generator.

Postischemic IGF-1 gene transfer promotes neurovascular regeneration after experimental stroke

Promoting neural regeneration after cerebral infarction has emerged as a potential approach for the treatment of stroke. Insulin-like growth factor 1 (IGF-1) possesses both neurotrophic and angiogenic properties. The aim of this study was to determine whether postischemic gene transfer of IGF-1 enhances neurovascular regeneration in a mouse model of permanent focal cerebral ischemia. Long-term cerebral IGF-1 overexpression was achieved with adeno-associated viral vector (AAV) by stereotaxic injection at 24 h after a stroke. Adeno-associated viral vector-green fluorescent protein (GFP) or saline was injected as a control. The success of postischemic gene transduction was confirmed by a strong GFP signal and by increased IGF-1 protein expression in the peri-infarct region. Postischemic gene transfer of IGF-1 significantly enhanced vascular density at 8 weeks after a stroke in the peri-infarct and injection needle tract area compared with AAV-GFP or saline treatment, as shown by immunohistochemical staining with the vascular marker lectin. Furthermore, increased vascular density was associated with improved local vascular perfusion. Immunohistochemical staining with the neuronal progenitor marker, DCX (doublecortin), and the cell proliferation marker, BrdU (5-bromo-2-deoxyuridine-5-monophosphate), indicated that AAV-IGF-1 treatment potently increased neurogenesis compared with AAV-GFP injection. These data show that postischemic treatment of IGF-1 effectively promoted neural and vascular regeneration in the chronic stage of cerebral infarction.

Distribution of pathogenic Yersinia enterocolitica in China

Yersinia enterocolitica (1,295 strains) was isolated from diarrhea patients, livestock, poultry, wild animals, insect vectors, food, and the environment. They were studied for epidemiology distribution using bacterial biochemical metabolism tests, their virulence genes, and pulsed-field gel electrophoresis (PFGE) sub-typing. The data showed that 416 of the 1,295 strains were pathogenic, where the pathogenic Chinese isolates were of serotypes O:3 and O:9. These two serotypes were found in livestock and poultry, with swine serving as the major reservoir. The geographic distribution of pathogenic isolates was significantly different, where most of the strains were isolated from the cold northern areas, whereas some serotype O:3 strains were recovered from the warm southern areas. By the analysis of the data of the Ningxia Hui Autonomous Region, we find the phenomenon of 'concentric circle distribution' around animal reservoirs and human habitation. The clustering of PFGE showed that the patterns of the pathogenic strains isolated from diarrhea patients were identical compared to those from the animals in the same area, thus, suggesting that the human infection originated from the animals.

Nitric oxide in vascular endothelial growth factor-induced focal angiogenesis and matrix metalloproteinase-9 activity in the mouse brain

BACKGROUND AND PURPOSE

Vascular endothelial growth factor (VEGF) can induce matrix metalloproteinase (MMP)-9 activities and focal angiogenesis. We hypothesized that VEGF activation of cerebral MMP-9 would require nitric oxide participation.

METHODS

We compared the in vivo effects of: (1) N(G)-monomethyl-l-arginine, a nonspecific nitric oxide synthase inhibitor; (2) L-N(6)-(1-iminoethyl)lysine, an inducible nitric oxide synthase selective inhibitor; and (3) doxycycline, a known nonspecific inhibitor of MMP in the mouse brain, using in situ zymography and endothelial marker CD31. 3-nitrotyrosine was used as a surrogate for nitric oxide activity. Inflammatory cell markers CD68 and MPO were used to confirm leukocyte infiltration.

RESULTS

VEGF-stimulated MMP-9 activity expressed primarily around cerebral microvessels. N(G)-monomethyl-l-arginine suppressed cerebral angiogenesis (P<0.05), especially those microvessels associated with MMP-9 activation (P<0.02) induced by VEGF, comparable to the effect of doxycycline. L-N(6)-(1-iminoethyl)lysine showed similar inhibitory effects. 3-nitrotyrosine confirmed nitric oxide levels in the brain. Compared with the lacZ control, VEGF increased inflammatory cell infiltration, especially macrophages, in the induced brain angiogenic focuses.

CONCLUSIONS

Inhibition of nitric oxide production decreased MMP-9 activity and focal angiogenesis in the VEGF-stimulated brain. Both specific and nonspecific inhibition of nitric oxide synthase resulted in similar reductions, suggesting that VEGF-stimulated cerebral MMP activity and angiogenesis are predominantly mediated through inducible nitric oxide synthase, a specific nitric oxide synthase isoform mediating inflammatory responses.

Low-power, intelligent sensor hardware interface for medical data preprocessing

This work proposes an interface design of a low-power programmable system on chip for intelligent wireless sensor nodes to reduce the overall power consumption of the heart disease monitoring system, by lending them the capability of processing complex functions and performing rapid computations on a large amount of data at the node. This facilitates the node to intelligently monitor a medical signal for impending events instead of transmitting the signal to the base station constantly. Lowering the transmission data rate decreases the transmission power consumption in a node, thereby lengthening the node life and in turn increasing the reliability of the network. This work also implements a thresholding technique, which controls the data transmission rate depending on the value of the monitored signal, and a cardiac monitoring system that performs computations at the node for the detection of either a skipped heart beat or a reduced heart rate variability, in which event the signal is transmitted to the base station for monitoring/recording or alerting the crew. The performance analysis of the system shows that there are reductions in the system power consumption and data transmission rate, which in turn reduces the network traffic and averts congestion.

Reversible Cerebral Vasoconstriction Syndrome with Posterior Leucoencephalopathy after Oral Contraceptive Pills

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by sudden-onset recurrent ‘thunderclap’ headaches with reversible multifocal narrowing of the cerebral arteries, often associated with focal neurological deficits from ischaemic or haemorrhagic stroke. It has been associated with exposure to vasoconstrictive drugs, pregnancy, migraine, and a variety of other conditions. Whereas the pathophysiology of RCVS remains unclear, changes in the levels of female hormones are considered important because RCVS predominantly affects women and is frequently associated with pregnancy. We report a patient with angiographically confirmed RCVS whose MRI showed reversible brain oedema, suggesting an overlap between RCVS and the reversible posterior leucoencephalopathy syndrome. The only identified risk factor was oral contraceptive pills started 1 month prior to onset, supporting a role for female reproductive hormones in precipitating this overlap syndrome.

Development of a cerebral microvascular dysplasia model in rodents

Normal vasculature development of the central nervous system is extremely important because patients with vascular malformations are at life-threatening risk for intracranial hemorrhage or cerebral ischemia. The etiology and pathogenesis of abnormal vasculature development in the central nervous system are unknown, and progress is hampered by the lack of animal models for human cerebrovascular diseases. Here, we report our current study on cerebral microvascular dysplasia (CMVD) development. Using vascular endothelial growth factor hyper-stimulation, we demonstrated that aberrant microvessels could be developed in the rodent brain under certain conditions (such as genetic deficient background, local cytokine and chemokine release, or exogenous vessel dilating stimulation) that may speed up focal angiogenesis and lead to cerebral vascular dysplasia.

A hybrid approach for compressive neural activity detection with functional MR images

In this paper, we present a framework for neural activity detection using fMRI data, based on both statistical data analysis (data-driven) and graphical information modeling (model-based). The data-driven approaches do rough prediction when an extraordinary amount of neural activities arise. By proper exploration of spatial, temporal, inter-subject correlations, the model-based approaches can provide more insights to details, and physiological meaning from high data volume, low signal-to-noise ratio (SNR) fMRI measurements. Through temporal cluster analysis (TCA), matched filtering, linear predictive coding (LPC), and variational Bayesian Gaussian mixture modeling (VBGMM), the temporal fMRI signals are converted into event prototypes associated with three neural statuses: activation, deactivation, and normality. As a result, the high volume fMRI data generated from multiple subjects can be statistically modeled as coupled finite-state sequences. Based on the graphical-model representation, the neural activities captured through fMRI can be classified and detected at reduced computational cost. The whole framework consists of three components: 1) image enhancement, event prediction and capture; 2) event feature extraction and modeling; and 3) graphical model based Bayesian inference. The experiment results demonstrate the advantages of the proposed hybrid, compressive signal processing approach in terms of computational cost and robustness against inter-subject variability as well as various artifacts.

Production, characterization, and efficient transfection of highly pure oligodendrocyte precursor cultures from mouse embryonic neural progenitors

Much current knowledge of oligodendrocyte biology, the myelin-forming cells in the central nervous system, comes from cell culture studies mainly from postnatal rat tissue but mouse cells have been much more difficult to produce in large quantities. We have developed a high yield protocol for production of oligodendrocyte precursor cells from mouse embryonic neural progenitors grown as neurospheres. Neurospheres can be maintained and expanded for long periods in culture in the presence of epidermal growth factor (EGF). When floating neurospheres were plated on substrate-coated dishes in media supplemented with platelet derived growth factor (PDGF) and basic fibroblast growth factor (bFGF), the spheres attached and generated migrating cells that were predominantly oligodendrocyte-lineage cells. Furthermore, cells in spheres could be shifted to the oligodendrocyte phenotype prior to plating on substrate, by incubation in suspension with PDGF/bFGF. Single cell suspensions plated after dissociation of either EGF-treated neurospheres or PDGF/bFGF-treated oligospheres had the bipolar, elongated morphology characteristic of oligodendrocyte precursor cells. mRNA and protein expression analysis of the cells generated by this method confirmed their oligodendrocyte lineage. Oligodendrocyte precursors generated by this method matured in response to ciliary neurotrophic factor treatment, producing cells with multiple processes and myelin-like membranes. The most important aspect of this protocol is the ability to generate very high numbers of relatively pure mouse oligodendrocyte progenitor cells, which can be easily transfected. These studies open up many kinds of investigations on transgenic and mutant mouse oligodendrocytes, thereby providing a valuable tool to study oligodendrocyte biology and development.

Increased tissue perfusion promotes capillary dysplasia in the ALK1-deficient mouse brain following VEGF stimulation

Loss-of-function activin receptor-like kinase 1 gene mutation (ALK1+/-) is associated with brain arteriovenous malformations (AVM) in hereditary hemorrhagic telangiectasia type 2. Other determinants of the lesional phenotype are unknown. In the present study, we investigated the influence of high vascular flow rates on ALK1+/- mice by manipulating cerebral blood flow (CBF) using vasodilators. Adult male ALK1+/- mice underwent adeno-associated viral-mediated vascular endothelial growth factor (AAVVEGF) or lacZ (AAVlacZ as a control) gene transfer into the brain. Two weeks after vector injection, hydralazine or nicardipine was infused intraventricularly for another 14 days. CBF was measured to evaluate relative tissue perfusion. We analyzed the number and morphology of capillaries. Results demonstrated that hydralazine or nicardipine infusion increased focal brain perfusion in all mice. It was noted that focal CBF increased most in AAVVEGF-injected ALK1+/- mice following hydralazine or nicardipine infusion (145+/-23% or 150+/-11%; P<0.05). There were more detectable dilated and dysplastic capillaries (2.4+/-0.3 or 2.0+/-0.4 dysplasia index; P<0.01) in the brains of ALK1+/- mice treated with AAVVEGF and hydralazine or nicardipine compared with the mice treated with them individually. We concluded that increased focal tissue perfusion and angiogenic factor VEGF stimulation could have a synergistic effect to promote capillary dysplasia in a genetic deficit animal model, which may have relevance to further studies of AVMs.

Contribution of bone marrow-derived cells associated with brain angiogenesis is primarily through leukocytes and macrophages

OBJECTIVE

We investigated the role of bone marrow-derived cells (BMDCs) in an angiogenic focus, induced by VEGF stimulation.

METHODS AND RESULTS

BM from GFP donor mice was isolated and transplanted into lethally irradiated recipients. Four weeks after transplantation, groups of mice received adeno-associated viral vector (AAV)-VEGF or AAV-lacZ gene (control) injection and were euthanized at 1 to 24 weeks. BMDCs were characterized by double-labeled immunostaining. The function of BMDCs was further examined through matrix metalloproteinase (MMP)-2 and -9 activity. We found that capillary density increased after 2 weeks, peaked at 4 weeks (P<0.01), and sustained up to 24 weeks after gene transfer. GFP-positive BMDCs infiltration in the angiogenic focus began at 1 week, peaked at 2 weeks, and decreased thereafter. The GFP-positive BMDCs were colocalized with CD45 (94%), CD68 (71%), 5% Vimentin (5%), CD31/von Willebrand factor (vWF) (1%), and alpha-smooth muscle actin (alpha -SMA, 0.5%). Infiltrated BMDCs expressed MMP-9. MMP-9 KO mice confirmed the dependence of the angiogenic response on MMP-9 availability.

CONCLUSIONS

Nearly all BMDCs in the angiogenic focus showed expression for leukocytes/macrophages, indicating that BMDCs minimally incorporated into the neovasculature. Colocalization of MMPs with GFP suggests that BMDCs play a critical role in VEGF-induced angiogenic response through up-regulation of MMPs.

Del-1 gene transfer induces cerebral angiogenesis in mice

Developmental endothelial locus-1 (Del-1) is a novel angiomatrix protein that has been shown to stimulate a potent angiogenic response and promote functional recovery in hind-limb and cardiac ischemia in animal models; however, its impact on cerebral angiogenesis is unknown. In this study, we investigated whether Del-1 overexpression via gene transfer induces cerebral angiogenesis in a murine model, and examined Del-1 expression after ischemic stroke. Cerebral Del-1 overexpression was achieved with AAV (adeno-associated virus) transduction system via stereotactic injection. Control mice were injected with AAV-lacZ. Del-1 gene transduction led to a significant induction of cerebral angiogenesis compared to AAV-lacZ treatment at 4 weeks after gene transfer (Del-1: 97+/-7 vs lacZ: 64+/-28, vessels/field, p<0.05). Mice transduced with AAV-Del-1 showed significantly elevated vascular densities for up to 6 weeks after gene delivery. In addition, double immunofluorescent staining showed co-localization of endothelial cell marker CD31 with BrdU (specific marker for proliferating cells), indicating that Del-1 promoted endogenous endothelial cell proliferation and angiogenesis. Our immunohistochemical staining also showed that Del-1 expression was markedly up-regulated in the peri-infarct area at 3 days after permanent focal cerebral ischemia compared to the sham-operated non-ischemic control. Our data suggest that Del-1 may participate in modulating cerebral angiogenesis, and that gene transfer of Del-1 may provide a novel and potent means for stimulating cerebral angiogenesis.

Upregulation of EMMPRIN after permanent focal cerebral ischemia

Elevated activities of matrix metalloproteinases (MMPs) following ischemic stroke have been shown to mediate ischemic injury as well as neurovascular remodeling. The extracellular MMP inducer (EMMPRIN) is a 58-kDa cell surface glycoprotein, which has been known to play a key regulatory role for MMP activities. The roles of EMMPRIN in stroke injury are not clearly understood. In this study, we investigated changes of EMMPRIN in a mouse model of permanent focal cerebral ischemia, and examined potential association between EMMPRIN and MMP-9 expression. Adult male CD-1 mice were subjected to permanent focal ischemia by intraluminal occlusion of the left middle cerebral artery (MCAO) under anesthesia. EMMPRIN expression was markedly upregulated in the peri-infarct area at 2-7 days after ischemia compared to the contralateral non-ischemic hemisphere by Western blot analysis. Immunofluorescent double staining demonstrated that EMMPRIN signals co-localized with vwF-positive endothelial cells and GFAP-positive peri-vascular astrocytes. In contrast, EMMPRIN signal did not co-localize with NeuN-positive neurons, or MPO-positive neutrophils. Dual fluorescent staining revealed that EMMPRIN co-localized with MMP-9. Our data also demonstrated that increased EMMPRIN expression correlated with increased MMP-9 levels in a temporal manner. In summary, we report for the first time that EMMPRIN expression was significantly increased in a mouse model of permanent focal cerebral ischemia. The spatial and temporal association between increased EMMPRIN expression and elevated MMP-9 levels suggest that EMMPRIN may modulate MMP-9 activity, and participate in neurovascular remodeling after ischemic stroke.

Neutrophil depletion decreases VEGF-induced focal angiogenesis in the mature mouse brain

To explore the role of neutrophil-derived matrix metalloproteinases (MMPs) during angiogenesis in the brain, we hypothesized that transient neutrophil depletion attenuates the angiogenic response to focal hyperstimulation with vascular endothelial growth factor (VEGF). Brain focal angiogenesis was achieved using an adeno-associated virus delivered VEGF (AAV-VEGF) gene transfer in the mature mouse. Four groups of mice underwent AAV vector injection in the brain parenchyma: (1) AAV-LacZ; (2) AAV-VEGF; (3) AAV-VEGF plus anti-polymorphonuclear (PMN) antibody; and (4) AAV-VEGF plus serum. Animals in groups 3 and 4 underwent 4 days of PMN antibody or serum treatment before transfection; treatment was sustained for an additional 14 days. Anti-PMN treatment decreased circulating neutrophils to 9% of baseline (P<0.001). Microvessels in the AAV-VEGF-group increased 25% compared with the AAV-lacZ-transduced group (256+/-15 versus 208+/-16; P<0.05). Anti-PMN treatment attenuated the increase to 10% compared with control serum treatment (234+/-16 versus 255+/-22; P<0.05). Similarly, compared with control serum treatment, anti-PMN treatment also reduced MMP-9 by 50% (2+/-0.9 versus 4+/-1.4; P<0.05) and MPO expression by 25% (2+/-0.8 versus 3+/-0.9; P<0.05); MMP-9 activity correlated with MPO expression (R(2)=0.8, P<0.05). Our study demonstrated that transient depletion of neutrophils suppressed VEGF-induced angiogenesis, indicating that circulating neutrophils contribute to VEGF-induced focal angiogenesis. In addition, brain MMP-9 activity was attenuated after neutrophil depletion, suggesting that neutrophil is an important source of MMP-9.

High-yield expression, purification and characterization of tumor-targeted IFN-alpha2a

BACKGROUND

IFN-alpha has been shown to be effective against hematologic malignancies. However, it is ineffective against most solid tumors and has not been satisfactory because of its toxicity.

METHODS

The NGR (Asn-Gly-Arg) peptide is a tumor-homing peptide. In order to increase the anti-tumor activity of IFN-alpha2a and lower the dose, we coupled a cyclic NGR peptide with the C terminus of IFN-alpha2a (named IFN-alpha2a-NGR).

RESULTS

The fusion protein was expressed in E. coli and purified by ion-exchange chromatography. The purity of IFN-alpha2a-NGR was >98% and the final purification yield of IFN-alpha2a-NGR was approximately 18 mg/L. The anti-tumor efficacy and the binding ability of IFN-alpha2a-NGR with tumor vasculature were investigated in vitro and in vivo.

DISCUSSION

Our study has demonstrated that the anti-tumor efficacy of IFN-alpha2a-NGR is significantly increased in comparison with IFN-alpha2a, and IFN-alpha2a-NGR could selectively target tumor vessels. These data indicate that the tumor-homing peptide (NGR) can enhance the therapeutic efficacy of IFN-alpha2a against tumors.

A pyroelectric infrared biometric system for real-time walker recognition by use of a maximum likelihood principal components estimation (MLPCE) method

This paper presents a novel biometric system for real-time walker recognition using a pyroelectric infrared sensor, a Fresnel lens array and signal processing based on the linear regression of sensor signal spectra. In the model training stage, the maximum likelihood principal components estimation (MLPCE) method is utilized to obtain the regression vector for each registered human subject. Receiver operating characteristic (ROC) curves are also investigated to select a suitable threshold for maximizing subject recognition rate. The experimental results demonstrate the effectiveness of the proposed pyroelectric sensor system in recognizing registered subjects and rejecting unknown subjects.

Variables which might predict the response to salvage radiotherapy in chinese patients with biochemical failure after radical prostatectomy

BACKGROUND/AIMS

To evaluate the relationship between the variables and the outcomes of salvage radiotherapy (sRT) to find some predictors of sRT.

METHODS

The medical records of 56 patients receiving sRT for biochemical failure after radical prostatectomy (RP) were available for retrospective review. sRT was defined as external beam radiotherapy for patients with a continuous increase in the prostate-specific antigen (PSA) level of >or=0.2 ng/ml after RP. Response was defined as achievement of a PSA nadir of <or=0.1 ng/ml.

RESULTS

The mean follow-up period after sRT was 31.6 months. The predictors of response to sRT were PSA doubling time (PSADT) and seminal vesicle invasion. The median PSADT in responders was 6.5 months versus 4.0 months in non-responders (OR=1.66, p=0.006). The patients with a PSADT of >6 months were all responders. The response rate in patients with seminal vesicle invasion was 42.9% (6/14) versus 76.2% (32/42) in patients without seminal vesicle invasion (OR=0.119, p=0.015).

CONCLUSION

PSADT and the state of seminal vesicle invasion were good predictors of response to sRT. sRT was especially effective when the PSADT was >6 months and in patients without seminal vesicle invasion.