A small world of neuronal synchrony

A small-world network has been suggested to be an efficient solution for achieving both modular and global processing-a property highly desirable for brain computations. Here, we investigated functional networks of cortical neurons using correlation analysis to identify functional connectivity. To reconstruct the interaction network, we applied the Ising model based on the principle of maximum entropy. This allowed us to assess the interactions by measuring pairwise correlations and to assess the strength of coupling from the degree of synchrony. Visual responses were recorded in visual cortex of anesthetized cats, simultaneously from up to 24 neurons. First, pairwise correlations captured most of the patterns in the population's activity and, therefore, provided a reliable basis for the reconstruction of the interaction networks. Second, and most importantly, the resulting networks had small-world properties; the average path lengths were as short as in simulated random networks, but the clustering coefficients were larger. Neurons differed considerably with respect to the number and strength of interactions, suggesting the existence of "hubs" in the network. Notably, there was no evidence for scale-free properties. These results suggest that cortical networks are optimized for the coexistence of local and global computations: feature detection and feature integration or binding.

Administration of intracoronary bone marrow mononuclear cells on chronic myocardial infarction improves diastolic function

BACKGROUND

Regeneration of the myocardium and improved ventricular function have been demonstrated in patients with acute myocardial infarction (MI) treated by intracoronary delivery of autologous bone marrow mononuclear cells (BMC) a few days after successful myocardial reperfusion by percutaneous coronary intervention (PCI); however, the effects of intracoronary cell infusion in chronic MI patients are still unknown.

AIMS

To investigate whether intracoronary infusion of BMC into the infarct-related artery in patients with healed MI could lead to improvement in left ventricular (LV) function.

METHODS

Among 47 patients with stable ischaemic heart disease due to a previous MI (13 (SD 8) months previously), 24 were randomised to intracoronary infusion of BMC (BMC group) and 23 to a saline infusion (control group) into the target vessel after successful PCI within 12 hours after chest pain occurred. LV systolic and diastolic function, infarct size and myocardial perfusion defect were assessed with the use of echocardiography, magnetic resonance imaging (MRI) or (201)Tl single-photon-emission computed tomography (SPECT) at baseline and repeated at the 6-month follow-up examination.

RESULTS

BMC treatment did not result in a significant increase in LV ejection fraction in any of the groups by any of the methods used, and the apparent tendency of an improvement was not statistically different between the two groups. The two groups also did not differ significantly in changes of LV end-diastolic and systolic volume, infarct size or myocardial perfusion. However, there was an overall effect of BMC transfer compared with the control group with respect to early/late (E/A) (p<0.001), early diastolic velocity/late diastolic (Aa) velocity (Ea/Aa) ratio (p = 0.002) and isovolumetric relaxation time (p = 0.038) after 6 months, as evaluated by tissue Doppler echocardiography. We noted no complications associated with BMS transfer.

CONCLUSION

Intracoronary transfer of autologous BMC in patients with healed MI did not lead to significant improvement of cardiac systolic function, infarct size or myocardial perfusion, but did lead to improvement in diastolic function.

Cortical demyelination in PML and MS: Similarities and differences

OBJECTIVE

To characterize pathologic changes in the cerebral cortex of patients with multiple sclerosis (MS) and progressive multifocal leukoencephalopathy (PML).

METHODS

Autopsy brain tissue was obtained from 13 patients with PML, 4 patients with MS, 2 patients with HIV encephalopathy, and 1 subject without neurologic pathology. Immunohistochemistry for myelin proteins, inflammatory cells, and neurofilaments was performed to evaluate the distribution of cortical lesions, their inflammatory activity, and neuritic pathology. Confocal microscopy was applied to examine pathologic changes in neurites in PML cortex.

RESULTS

Leukocortical, intracortical, and subpial patterns of cortical demyelination were represented in MS brain tissue. In PML brain tissue intracortical and leukocortical but not subpial lesions were observed. Cortical lesions in PML and MS contained fewer inflammatory cells than demyelinated areas in the white matter. Neuritic pathology in cortical PML lesions was represented by dystrophic and transected neurites. Pathologic modifications in neuritic processes in PML were more evident in highly inflamed white matter than in gray matter areas of demyelination, reminiscent of previous reports of neuritic pathology in MS. JC virus-infected cells were associated with PML white matter, leukocortical and intracortical lesions.

CONCLUSIONS

Cortical pathology represents a distinct feature of progressive multifocal leukoencephalopathy. Similarities and differences with regard to multiple sclerosis cortical pathology were noted and may be informative regarding the pathogenesis of both disorders.

Significant alterations of biodistribution and immune responses in Balb/c mice administered with adenovirus targeted to CD40(+) cells

CD40 ligation has been shown to promote antigen-presenting functions of dendritic cells, which express CD40 receptor. Here we reported significantly altered biodistribution and immune responses with the use of CD40-targeted adenovirus. Compared with unmodified adenovirus 5, the CD40-targeted adenovirus following intravenous administration (i.v.) resulted in increased transgene expressions in the lung and thymus, which normally do not take up significant amounts of adenovirus. Intradermal injection saw modified adenovirus being mainly processed in local draining lymph nodes and skin. Following intranasal administration (i.n.), neither unmodified nor targeted viruses were found to be in the liver or spleen, which predominantly took up the virus following i.v. administration. However, inadvertent infection of the brain was found with unmodified adenoviruses, with the second highest gene expression among 14 tissues examined. Importantly, such undesirable effects were largely ablated with the use of targeted vector. Moreover, the targeted adenovirus elicited more sustained antigen-specific cellular immune responses (up to 17-fold) at later time points (30 days post boosting), but also significantly hampered humoral responses irrespective of administration routes. Additional data suggest the skewed immune responses induced by the targeted adenoviruses were not due to the identity of the transgene but more likely a combination of overall transgene load and CD40 stimulation.

Vanishing liver tumours

Spontaneous resolution of liver tumours is a rare, but recognized entity that has been reported to occur within the spectrum of benign and malignant liver tumours occurring in both adult and paediatric population. The aetiology of this unusual phenomenon is not clearly understood. In this article we present case examples of various benign and malignant liver tumours that have regressed spontaneously without treatment together with a review of the literature, and a summary of the current understanding of the pathogenesis of these tumours.

Prospective observational study of acute coronary syndromes in China: practice patterns and outcomes

OBJECTIVE

To describe the investigation and management of patients admitted to hospitals in China with suspected acute coronary syndromes (ACS) and to identify potential areas for improvement in practice.

DESIGN

A multicentre prospective survey of sociodemographic characteristics, medical history, clinical features, in-hospital investigations, treatment practices and major events among patients with suspected ACS.

SETTING

Large urban public hospitals.

PATIENTS

Consecutive patients admitted to in-patient facilities with a diagnosis of suspected acute myocardial infarction (MI) or unstable angina pectoris.

MAIN OUTCOME MEASURES

Myocardial infarction/re-infarction, heart failure, death.

RESULTS

Between September 2004 and May 2005, data were collected prospectively from 2973 patients admitted to 51 hospitals in 18 provinces of China. An initial diagnosis of ST elevation MI, non-ST elevation MI and unstable angina was made in 43%, 11% and 46% of patients, respectively. Diagnosis was inconsistent with objective measures in up to 20% of cases. At both tertiary and non-tertiary centres, there was little evidence that clinical risk stratification was used to determine the intensity of investigation and management. The mortality rate during hospitalisation was 5% overall and similar in tertiary and non-tertiary centres, but reported in-hospital re-infarction rates (8%) and heart failure rates (16%) were substantially higher at non-tertiary centres.

CONCLUSION

This study has identified a number of areas in the management of ACS patients, including diagnosis and risk stratification, which deviate from current guidelines. These findings will help inform the introduction of widely used quality improvement initiatives such as clinical pathways.

Identification of vip3A-type genes from Bacillus thuringiensis strains and characterization of a novel vip3A-type gene

AIMS

To search for novel Vip3A proteins for controlling insect pests.

METHODS AND RESULTS

A pair of universal primers was designed based on the conserved regions of five vip3A genes. Amplified products were digested with the HindIII and EcoR enzymes so as to confirm different restriction fragment length polymorphism (RFLP) patterns used to identify vip3A-type genes. The vip3A gene types of 606 Bacillus thuringiensis strains were screened and three patterns of RFLP were successfully identified. Two novel vip3A genes were found and one of these, vip3Aa19, was further characterized and its product was confirmed toxic to Spodoptera exigua, Helicoverpa armigera and Plutella xylostella larvae. Partial sequences of another novel vip3A-type gene were obtained that shared 83% homology with that of the vip3Af1 gene.

CONCLUSIONS

A polymerase chain reaction (PCR)-RFLP system we developed could be used for identifying novel vip3A-genes from B. thuringiensis strains. A novel Vip3A protein was found to have a broader insecticidal spectrum.

SIGNIFICANCE AND IMPACT OF THE STUDY

The reported method is a powerful tool to find novel Vip3A proteins from large-scale B. thuringiensis strains. The novel Vip3A protein may be used to control insect pests or resistant insect pests by constructing genetically engineered strains or transgenic plants.

Improving toxicity of Bacillus thuringiensis strain contains the cry8Ca gene specific to Anomala corpulenta larvae

The cry8C-type gene designated cry8Ca2, which was cloned and sequenced from a Bacillus thuringiensis isolate HBF-1 in China, consisted of an open reading frame of 3483 bp encoding a protein of 1160 amino-acid residues. Sequence analysis showed that the Cry8Ca2 protoxin of 130.5 kDa had 99.9% sequence homology with the previously reported Cry8Ca1 protein, with one mismatch between the two amino-acid sequences. When the Cry8Ca2 toxin was expressed in a crystal-negative strain of B. thuringiensis (HD-73(-)), elliptical crystals were produced. Cell extracts from this recombinant strain showed insecticidal activity against Anomala corpulenta larva. Mutant cry8Ca2 genes, produced by polymerase chain reaction amplification with Taq DNA polymerase, were used to develop recombinant B. thuringiensis strains. Mutants producing higher levels of insecticidal activity were identified by bioassay. Thirty-five mutants forming crystals were characterized, and two of them showed significantly increased insecticidal activity against A. corpulenta larva. The 50% lethality concentrations (LC(50)) of the two mutants were 0.2334 x 10(8) and 0.2591 x 10(8) colony-forming units g(-1), considerably lower than the LC(50) of the wild-type strain HBF-1 (0.9583 x 10(8) CFU g(-1)) and that of B. thuringiensis serovar japonensis strain Buibui (1.0752 x 10(8) CFU g(-1)).

Effective gene selection method with small sample sets using gradient-based and point injection techniques

Microarray gene expression data usually consist of a large amount of genes. Among these genes, only a small fraction is informative for performing cancer diagnostic test. This paper focuses on effective identification of informative genes. We analyze gene selection models from the perspective of optimization theory. As a result, a new strategy is designed to modify conventional search engines. Also, as overfitting is likely to occur in microarray data because of their small sample set, a point injection technique is developed to address the problem of overfitting. The proposed strategies have been evaluated on three kinds of cancer diagnosis. Our results show that the proposed strategies can improve the performance of gene selection substantially. The experimental results also indicate that the proposed methods are very robust under all the investigated cases.

Degree of angle closure and extent of peripheral anterior synechiae: an anterior segment OCT study

AIMS

To evaluate the relationship between angle width as determined by anterior segment optical coherence tomography (AS-OCT) and the presence of peripheral anterior synechiae (PAS).

METHODS

This was a prospective observational case series in which 203 subjects with primary angle closure or open angles were recruited. Images of the nasal, temporal and inferior angles were obtained with AS-OCT in dark conditions. Subjects then underwent gonioscopy by an independent examiner who was masked to the AS-OCT findings. PAS were identified by gonioscopy and defined as abnormal adhesions of the iris to the angle that were at least half a clock hour in width and present to the level of the anterior trabecular meshwork or higher. The total clock hours of PAS were recorded.

RESULTS

Sixty-eight subjects (33.5%) were PACS, 76 subjects (37.4%) had PAC/PACG, 14 (6.9%) had primary open angle glaucoma, and 45 (22.2%) subjects were normal with open angles. There was a weak but significant correlation between the angle opening distance (AOD), trabecular iris space area (TISA) and angle recess area (ARA) with clock hours of PAS (Spearman's correlation coefficients = -0.30, -0.32 and -0.32, respectively, p<0.001). The mean values of the AOD, TISA and ARA in the nasal, temporal and inferior quadrants were significantly less in eyes with PAS compared with those without (p<0.001, Mann-Whitney U test). Analysis by quadrant showed that these parameters were smaller in the nasal and temporal quadrants in eyes with PAS (p<0.01).

CONCLUSIONS

Angle width determined by AS-OCT and the extent of PAS were weakly correlated, and angle width was significantly smaller in eyes with PAS.

Validation of quantitative fluorescence imaging analysis (QFIA) of β-catenin in archived prostate tissues for cancer biomarker discovery

15575

Background: The objective of this study was to develop a sensitive tissue proteomic assay for quantifying proteins (e.g. β- catenin) in tissues and prostate core biopsies by QFIA. A second objective was to apply the validated methodology to quantify other biomarkers for prostate cancer risk assessment, and to study oxidative stress in BPH, prostate cancer, the cancer field, and in inflammatory prostatitis in animals and human prostatitis. Methods: Biopsies from controls and cancer patients were depariffinized, the antigen retrieved, and labeled with a robotic BioGenex Stainer with a primary mouse monoclonal antibody (1/100) to β-catenin. A secondary goat anti-mouse IgG antibody (2° Ab 1/100) coupled with Alexa Fluor 568 was used as the indicator system. The Leica Fluorescence Microscope was calibrated and standardized with fluorescence beads, LNCAP cells, and BPH tissue sections. QFIA of β-catenin was validated by RPPA methacarn fixed tissues. Adjacent 4-micron tissue sections were analyzed by QFIA for total β-catenin content by RPPA. Results: Reproducibility was 10% or less for the LNCAP cells and BPH tissue controls. Adjacent tissue sections assayed by QFIA and RPPA exhibited a strong linear correlation (r=.97) as did tissues fixed in methacarn vs.10% buffered-formalin and assayed by QFIA (r=0.84). For the core biopsy specimens the average MPI (AMPI) from 40 to 200 acini was quantified. The AMPI of cancerous acini (CA) compared to nomal acini (NA) was reduced in 37 of 42 cases p<.02. ROC plots revealed that β-catenin expression in NAA identified 42% (95%CI 25 - 52%) of cancer cases, with 88% (95% CI 80%-96%) specificity. The tissue QFIA method was used to quantify oxidative stress biomarkers (MnSOD, HNE, 8-OHdG) and other field disease biomarkers (Connexin42, and UDP-glucose dehydrogenase (UGDH) in BPH, prostate cancer, and in prostatitis. Conclusions: A tissue based QFIA method has been developed for the quantification of β-catenin in prostate core biopsy specimens, and the method has been validated by RPPA. Assay of β-catenin in prostate core biopsy specimens shows promise as a potential biomarker for a profile defining individuals at risk for prostate cancer and studying oxidative stress in relation to the pathogenesis of disease.

No significant financial relationships to disclose.

Multiparameter estimation using only a chaotic time series and its applications

An important extension to the techniques of synchronization-based parameter estimation is presented. Based on adaptive chaos synchronization, several methods are proposed to dynamically estimate multiple parameters using only a scalar chaotic time series. In comparison with previous schemes, the presented methods decrease the cost of parameter estimation and are more applicable in practice. Numerical examples are used to demonstrate the effectiveness and robustness of the presented methods. As an example application, an implementation of multichannel digital communication is proposed, where multiparameter modulation is used to simultaneously transmit more than one digital message. From a theoretical perspective, such an encoding increases the difficulty to directly read out the message from the transmitted signal and decreases the implementation cost.

Identifying the biologically relevant gene categories based on gene expression and biological data: an example on prostate cancer

MOTIVATION

Most gene-expression based studies aim to identify genes with the capability of distinguishing different phenotypes. Although analysis at the genomic level is important, results of the molecular/cellular level are essential for understanding biological mechanisms. To deliver molecular/cellular-level results, a two-stage scheme is widely employed. This scheme just evaluates biological processes/molecular activities individually, totally overlooking the relationship between processes/activities. This treatment conflicts with the fact that most biological processes/molecular activities do not work alone. In order to deliver improved results, this shortcoming should be addressed.

RESULTS

We design a selection model from a novel perspective to directly detect important gene functional categories (each category represents a cellular process or a molecular activity). More importantly, the correlations between gene categories are considered. Contributed by this capability, the proposed method shows its advantages over others.

AVAILABILITY

the source code in Matlab is accessible via http://www.ee.cityu.edu.hk/~twschow/category_selection/category_selection.htm

Association of variants in theIL12Bgene with leprosy and tuberculosis

There is a great range in outcomes after mycobacterial infections, and this is probably due to individual variation in immune responses. One of the key cytokine regulators of the immune response is interleukin (IL-) 12. The IL12B gene encodes the p40 chain of both IL-12 and IL-23 and it has two major variant sites at which different alleles are associated with increased levels of gene expression and with susceptibility to a range of immune-related diseases. We hypothesized that IL12B variants associated with increased expression would be as associated with susceptibility to persistent mycobacterial infection. We tested this hypothesis by genotyping Indian subjects, having either leprosy or tuberculosis (TB), as well as ethnically matched controls. Subjects with leprosy were less likely to have the 3'UTR genotype associated with lower IL12B expression (P= 0.001). Subjects with TB were not only more likely to have the high-expressing IL12B promoter genotype (P= 0.01) but also more likely to have this in the same haplotype with the high expressing 3'UTR allele (P= 0.0009). These results suggest these infectious diseases may be improved by modulating IL-l2p40 production.