A CMOS neuroelectronic interface based on two-dimensional transistor arrays with monolithically-integrated circuitry

The ability to monitor and to elicit neural activity with a high spatiotemporal resolution has grown essential for studying the functionality of neuronal networks. Although a variety of microelectrode arrays (MEAs) has been proposed, very few MEAs are integrated with signal-processing circuitry. As a result, the maximum number of electrodes is limited by routing complexity, and the signal-to-noise ratio is degraded by parasitics and noise interference. This paper presents a single-chip neuroelectronic interface integrating oxide-semiconductor field-effect transistors (OSFETs) with signal-processing circuitry. After the chip was fabricated with the standard complementary-metal-oxide-semiconductor (CMOS) process, polygates of specific transistors were etched at die-level to form OSFETs, while metal layers were retained to connect the OSFETs into two-dimensional arrays. The complete removal of polygates was confirmed by high-resolution image scanners, and the reliability of OSFETs was examined by measuring their electrical characteristics. Through a gate oxide of only 7nm thick, each OSFET can record and stimulate neural activity extracellularly by capacitive coupling. The capability of the full chip in neural recording and stimulation was further experimented using the well-characterised escape circuit of the crayfish. Experimental results indicate that the OSFET-based neuroelectronic interface can be used to study neuronal networks as faithfully as conventional electrophysiological tools. Moreover, the proposed simple, die-level fabrication process of the OSFETs underpins the development of various field-effect biosensors on a large scale with on-chip circuitry.

Assessment of mitral valve volume by quantitative three-dimensional echocardiography in patients with rheumatic mitral valve stenosis

BACKGROUND

Thickening of mitral leaflets in rheumatic mitral valve stenosis is well described in necropsy studies; however, volume computation of the thickening mitral leaflets has not been attempted. 4trial fibrillation is one of the complications of rheumatic mitral stenosis. Quantitative assessment of thickened mitral valve and its relation to clinical complications is clinically desirable.

HYPOTHESIS

The study was undertaken to compare measurement of mitral valve volume in normal subjects and in patients with rheumatic mitral valve stenosis.

METHODS

An HP Sonos 2500 echocardiographic system with 5 MHz multiplane transesophageal transducer was used for data acquisition, and TomTec Echoscan computer setup was used to off-line volume computation. Study subjects included 10 normal subjects (mean age 44.8 years) and 36 patients with rheumatic mitral valve stenosis (22 female, 14 male) with an age range of 25 to 69 years (mean age 47 +/- 9.6 years). Mitral valve volumes were compared between the normal subjects and patients with mitral valve stenosis, and further comparison was made between the sinus rhythm (SR) and atrial fibrillation (AF) groups in patients with mitral valve stenosis. In all study subjects, the mitral valve area (MVA) was determined by two-dimensional echocardiography.

RESULTS

Quantitative three-dimensional (3-D) echocardiography showed that mitral valve volume was significantly larger in patients with mitral valve stenosis than in normal subjects (9.0 +/- 2.2 and 4.5 +/- 0.7 ml, respectively, p < 0.001). When patients with mitral valve stenosis were divided into the SR and AF groups, mitral valve volume was found to be significantly larger in the AF group than in the SR group (9.76 +/- 2.2 ml. and 7.72 +/- 1.5 ml, respectively, p < 0.01) and patients in the AF group tended to be older (p < 0.05) with larger left atrial diameter (LAD) (p < 0.01). However, MVA between the two groups showed no statistical significance (1.1 +/- 0.43 and 1.0 +/- 0.34 cm2, respectively, p > 0.2). When the study subjects were divided into two groups (< 50 and > or = 50 years) according to age, the comparison of mitral valve volume between these two groups (9.37 +/- 2.18 and 8.56 +/- 2.14 ml, p > 0.2) showed no statistical significance.

CONCLUSIONS

Quantitative 3-D echocardiography can be applied for the measurement of mitral valve volume in vivo. Patients with rheumatic mitral valve stenosis with atrial fibrillation have a propensity to have a larger mitral valve volume and are older than the patients with sinus rhythm; however, the age per se does not seem to be a cause for larger mitral valve volume.

The mechanism of Astragalus membranaceus' effects on the proliferation of human basal-like breast cancer cell line MDA-MB-468 from p53/MDM2 pathway

Abstract #2116

Background: Based on the expression of ER,PR and Her2, breast cancer is classified into several subtypes. Thereinto, basal-like type ("triple-negative" phenotype) is associated with poor prognosis. Patients with this type are unlikely to benefit from currently available targeted therapy. And some researches revealed traditional Chinese medicine could play an important role in breast cancer treatment. p53 mutations can be found in most of basal-like breast cancer patients and this type's cell lines. In our study, we mainly focused on the mechanism of Astragalus membranaceus' effect on the proliferation of MDA-MB-468 cell from p53/MDM2 pathway.&#x2028; Material and Methods: The MDA-MB-468 cells were intervened by Astragalus membranaceus Injection (AMI) which contains 1g/ml crude drugs. The effect of AMI on the proliferation of the MDA-MB-468 cells was detected by MTT assay and its time-effect relationship was observed by cell counting kit-8 (CCK-8) assay. At two days after AMI intervention, the mRNA expression of some indicators were assessed by Real-time Quantitative PCR, including p53, MDM2, EGFR, PIP, PI3K, Akt1, Akt2 and PTEN. The anti-proliferation effect of AMI on the cells proliferation was detected by MTT assay after PTEN gene was knocked down by the small interfering RNA (SiRNA), and the protein expressions of EGFR, p-Akt, MDM2 and p53 were obtained by in-cell western assay.&#x2028; Results: According to MTT assay, AMI could obviously inhibit the proliferation of the MDA-MB-468 cells (p&lt;0.05) and the effect was stronger when combined with Tarceva (p&lt;0.01); When the PTEN gene was knocked down, AMI only combined with Tarceva could inhibit the cells' proliferation (p&lt;0.005). CCK-8 assay showed that the anti-proliferation effect of AMI was positively correlated with the intervention duration. Real-time Quantitative PCR revealed that AMI could up-regulate the PTEN gene expression (p&lt;0.001) and down-regulate the p53 (p&lt;0.01), MDM2 (p&lt;0.01), Akt2 (p&lt;0.001) and PIP (p&lt;0.001) gene expressions. In-cell western assay indicated that p53 protein was down-regulated at 15min(p&lt;0.05) and 1h(p&lt;0.001), and p-Akt protein expression showed significant down-regulation at 15min(p&lt;0.01), 30min(p&lt;0.001) and 2d(p&lt;0.001) after AMI intervene; when AMI combined with Tarceva, the duration of the down-regulation effect to p53 and p-Akt were all prolonged, and EGFR and MDM2 expressions were down-regulated(p&lt;0.05, p&lt;0.005). After PTEN SiRNA intervene, AMI down-regulate p53 (p&lt;0.001), p-Akt (p&lt;0.005) and EGFR (p&lt;0.05) protein expressions; and its down-regulation effect to p-Akt reduced, but increased to p53, and EGFR.&#x2028; Discussion: AMI can significantly inhibit the proliferation of MDA-MB-468 cells and present a time-dependent manner. The effect became stronger after combined with Tarceva. The main mechanism of its anti-proliferation effect may be to activate the positive feedback loop of the p53/ MDM2 pathway. It negatively regulates the PI3K by up-regulating the PTEN gene expression to promote the phosphorylation at D3 point of PIP3, so Akt's phosphorylation level is down-regulated and the cells proliferation was inhibited.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2116.

Molecular recognition of acute myeloid leukemia using aptamers

Cell surface proteins can play important roles in cancer pathogenesis. Comprehensive understanding of the surface protein expression patterns of tumor cells and, consequently, the pathogenesis of tumor cells, depends on molecular probes against these proteins. To be effectively used for tumor diagnosis, classification and therapy, such probes would be capable of specific binding to targeted tumor cells. Molecular aptamers, designer DNA/RNA probes, can address this challenge by recognizing proteins, peptides and other small molecules with high affinity and specificity. Through a process known as cell-SELEX, we used live acute myeloid leukemia (AML) cells to select a group of DNA aptamers that can recognize acute myeloid leukemia cells with dissociation constants (Kds) in the nanomolar range. Interestingly, one aptamer (KH1C12), compared with two control cell lines (K562 and NB4), showed significant selectivity to the target AML cell line (HL60) and could recognize the target cells within a complex mixture of normal bone marrow aspirates. The other two aptamers KK1B10 and KK1D04 recognize targets associated with monocytic differentiation. Our studies demonstrate that the selected aptamers can be used as a molecular tool for further understanding surface protein expression patterns on tumor cells and thus providing a foundation for effective molecular analysis of leukemia and its subcategories.

Magnetotransport properties in K(0.50)CoO(2) single crystals

We have measured susceptibility and angle-dependent magnetoresistance (AMR) on K(0.50)CoO(2) single crystals. A possible magnetic structure similar to that of Na(0.5)CoO(2), a G-type anti-ferromagnetic (AF) structure (both in-plane and inter-plane are AF), is proposed. At ∼20 K, a loop is observed between zero-field-cooled (ZFC) and field-cooled (FC) susceptibility. The absolute value of magnetoresistance (MR) at 20 K is much larger than other cases with H applied within the ab plane. This could arise from the magnetic field being applied in the ab plane, leading to spin-flop of the small magnetic moment of Co(3.5-δ) sites at 20 K to form in-plane ferromagnetic ordering, as observed in Na(0.52)CoO(2).

Ocular complications of heart transplantation in a Chinese population

The purpose of this study was to investigate ocular complications among a group of patients on long-term, high-dose immunosuppression and corticosteroids for the maintenance of orthotopic heart transplants. Additionally, we provided information pertinent for the early diagnosis and treatment of eye diseases. In this study, we retrospectively assessed the clinical data of 138 patients with orthotopic heart transplantations from May 2000 to October 2005, including assessment of ophthalmic symptoms and signs, as well as the general condition, treatment, and prognosis. Of 138 transplant recipients examined (276 eyes), 47 eyes (17.0%) showed ocular surface diseases. Sixty-four (23.2%) had a posterior subcapsular cataract, and 16 (5.8%) corticosteroid glaucoma. Fifteen (5.6%) had ocular fundus diseases. Various ocular complications related to immunosuppression and corticosteroids appear among heart transplant patients. Cardiac surgeons and ophthalmologists must closely evaluate ocular symptoms in the posttransplantation period.

Avian metapneumovirus subtype A in China and subtypes A and B in Nigeria

In order to detect and characterize avian metapneumovirus, organs or swabs were collected from 697 chicken and 110 turkeys from commercial farms in Southwestern Nigeria and from 107 chickens from live bird markets in Southeastern China. In Nigeria, 15% and 6% of the chicken and turkey samples, respectively, and 39% of the chicken samples from China, were positive for aMPV genome by PCR. The sequence of a 400 nt fragment of the attachment protein gene (G gene) revealed the presence of aMPV subtype A in both Nigeria and Southeastern China. Essentially identical subtype A viruses were found in both countries and were also previously reported from Brazil and the United Kingdom, suggesting a link between these countries or a common source of this subtype. In Nigeria, subtype B was also found, which may be a reflection of chicken importations from most major poultry-producing countries in Europe and Asia. In order to justify countermeasures, further studies are warranted to better understand the metapneumoviruses and their impact on poultry production.