Magnetostriction in Amorphous Co66Fe34 Microcantilevers Fabricated with Hydrogenated Amorphous Silicon

To study the magnetostriction of Co66Fe34 thin films, amorphous silicon microcantilevers were prepared by surface micromachining, and the 136 nm-thick magnetostrictive film was deposited by electron beam physical vapor deposition and patterned on top of the microcantilever structure. The magnetostriction of the Co66Fe34 films was confirmed by measuring the deflection of the cantilevers under a varying magnetic field, reaching displacements up to 8 nm. The configuration was simulated using COMSOL software, yielding a similar deflection behavior as a function of the magnetic field, with a film with a magneto strictive coefficient of λ S ~ 55 p.p.m. The experimental configuration uses a laser and a position sensitive detector to measure the displacement, based on an optical lever configuration, and a piezoelectric stage to calibrate the system.

Platelet Aggregation on Extracellular Matrix: Effect of a Recombinant GPIb-Binding Fragment of von Willebrand Factor

Platelets in whole blood incubated on extracellular matrix (ECM) produced by bovine corneal endothelial cells under oscillatory flow conditions demonstrate extensive aggregate formation. Since both platelet-subendothelium and platelet-platelet interactions are mediated by von Willebrand factor (vWF), we used this system to examine the effect of a recombinant GPIb-binding fragment of vWF (designated RG12986), comprising residues 445-733 of the native vWF subunit, on platelet reactivity with ECM. The seven cysteines present in the RG12986 fragment were reduced and alkylated in order to achieve a monomeric conformation. The recombinant vWF fragment binds to unstimulated platelets in the absence of exogenous modulators. When added to platelet-rich plasma, it inhibits ristocetin-induced platelet agglutination. Binding of 51Cr-labeled platelets in reconstituted whole blood to ECM was inhibited by RG12986 in a dose dependent and saturable manner, with IC50 of 4 μM and maximal inhibition (about 70%) at 6 μM. Scanning electron microscope (SEM) analysis showed that addition of RG12986 to whole blood significantly inhibited platelet aggregation on ECM. The extent of inhibition observed with RG12986 at a final concentration of 4 μM was similar to that obtained with the cell adhesion peptide RGDS at the concentration of 0.1 mM. The ability of the RG12986 fragment to inhibit platelet aggregation on ECM is in agreement with the concept that blockade of vWF-GPIb interaction may inhibit further events leading to activation of the glycoprotein IIb/IIIa (GPIIb/IIIa) complex and subsequent thrombus formation.

Study on the bio-functionalization of memristive nanowires for optimum memristive biosensors

Semiconductor nanowires are emerging as promising building blocks for biosensors enabling direct electrical detection of various biomolecules.

Distal antral gastropexy - a novel technique to prevent recurrence of giant hiatus hernia in selected cases - a cohort study

INTRODUCTION

The recurrence rate of giant hiatus hernias (GHH) following repair is high (30%) and increases with the hernia size and previous revision surgery. The mechanism of recurrence is poorly understood.

METHODS

This is a retrospective cohort study of all consecutive patients who underwent repair of giant hiatus hernia in a tertiary upper GI referral centre from November 2000 to November 2014. Patients who underwent redo surgery were identified and data on intra-operative findings and procedure performed at primary and redo surgery from their operation notes were collected.

RESULTS

A total of 81 patients underwent primary repair of GHH over the 14 year study period. 10 (12.3%) had symptomatic/radiological recurrence of which 4 were found to have the distal stomach herniating into the chest despite having an intact intra-abdominal wrap/gastropexy. To prevent migration of the distal stomach into the chest, distal gastropexy - fixing the antrum to the anterior abdominal wall, was added to 'conventional' gastropexy in 5 subsequent cases, in whom the antrum was in the chest preoperatively. These cases have no evidence of recurrence at the end of 6 months follow up.

CONCLUSION

Securing the antrum of stomach to the anterior abdominal wall may prevent migration of the distal stomach and other infracolic organs into the chest and thus reduce recurrence of some GHH where antrum had been in chest previously.

Bartonella henselae endocarditis in Laos - 'the unsought will go undetected'

Background

Both endocarditis and Bartonella infections are neglected public health problems, especially in rural Asia. Bartonella endocarditis has been described from wealthier countries in Asia, Japan, Korea, Thailand and India but there are no reports from poorer countries, such as the Lao PDR (Laos), probably because people have neglected to look.

Methodology/Principal Findings

We conducted a retrospective (2006–2012), and subsequent prospective study (2012–2013), at Mahosot Hospital, Vientiane, Laos, through liaison between the microbiology laboratory and the wards. Patients aged >1 year admitted with definite or possible endocarditis according to modified Duke criteria were included. In view of the strong suspicion of infective endocarditis, acute and convalescent sera from 30 patients with culture negative endocarditis were tested for antibodies to Brucella melitensis,Mycoplasma pneumoniae,Bartonella quintana,B. henselae,Coxiella burnetii and Legionella pneumophila. Western blot analysis using Bartonella species antigens enabled us to describe the first two Lao patients with known Bartonella henselae endocarditis.

Conclusions/Significance

We argue that it is likely that Bartonella endocarditis is neglected and more widespread than appreciated, as there are few laboratories in Asia able to make the diagnosis. Considering the high prevalence of rheumatic heart disease in Asia, there is remarkably little evidence on the bacterial etiology of endocarditis. Most evidence is derived from wealthy countries and investigation of the aetiology and optimal management of endocarditis in low income countries has been neglected. Interest in Bartonella as neglected pathogens is emerging, and improved methods for the rapid diagnosis of Bartonella endocarditis are needed, as it is likely that proven Bartonella endocarditis can be treated with simpler and less expensive regimens than “conventional” endocarditis and multicenter trials to optimize treatment are required. More understanding is needed on the risk factors for Bartonella endocarditis and the importance of vectors and vector control.

Infection of heart valves (endocarditis) with bacteria is an important condition, especially afflicting those with rheumatic heart disease, and has a high mortality if untreated. Most of the evidence for optimal antibiotic and surgical management comes from wealthy countries. There are no published data from poorer countries in SE Asia despite a high burden of rheumatic heart disease. We investigated the bacterial infections of heart valves in the Lao PDR (Laos) through heart ultrasound scans and analysis of patients' blood. We provide evidence of infection with the poorly understood bacteria Bartonella henselae (the cause of cat scratch disease) in two patients from Laos. We argue that it is likely that Bartonella endocarditis is more widespread than appreciated, as there are few laboratories in Asia able to make the diagnosis. This is important as it is likely that proven Bartonella endocarditis can be treated with simpler and less expensive regimens than “conventional” endocarditis. There have been great advances in the wealthy world in the diagnosis and treatment of endocarditis but these have not been assessed or implemented in poorer countries. More evidence on the causes and optimal management of endocarditis in low income countries is needed.

Infective endocarditis in the Lao PDR: clinical characteristics and outcomes in a developing country

INTRODUCTION

Data on infective endocarditis (IE) in Southeast Asia are scarce.

OBJECTIVES

To describe the clinical epidemiology of IE in Lao PDR, a lower middle-income country.

METHODS

A single centre retrospective study at Mahosot Hospital, Vientiane. Patients aged over 1year of age admitted 2006-2012 to Mahosot Hospital with definite or possible IE by modified Duke criteria were included.

RESULTS

Thirty-six patients fulfilled the inclusion criteria; 33 (91.7%) had left-sided IE. Eleven (30.6%) had definite IE and 25 (69.4%) possible left-sided IE. Median age was 25years old [IQR 18-42]. Fifteen patients (41.7%) were males. Underlying heart diseases included: rheumatic valve disease in 12 (33.3%), congenital heart disease in 7 (19.4%), degenerative valve disease in 3 (8.3%), and of unknown origin in 14 (38.9%) patients. Native valve IE was present in 30 patients (83.3%), and prosthetic valve IE in 6 patients (16.7%). The most frequent pathogens were Streptococcus spp. in 7 (19.4%). Blood cultures were negative in 22 patients (61.1%). Complications included: heart failure in 11 (30.6%), severe valve regurgitation in 7 (19.4%); neurological event in 7 (19.4%); septic shock or severe sepsis in 5 (13.9%); and cardiogenic shock in 3 patients (8.3%). No patient underwent heart surgery. Fourteen (38.9%) had died by follow-up after a median of 2.1years [IQR 1-3.2]; and 3 (8.3%) were lost to follow-up.

CONCLUSIONS

Infective endocarditis, a disease especially of young adults and mainly caused by Streptococcus spp., was associated with rheumatic heart disease and had high mortality in Laos.

On-chip sample preparation and analyte quantification using a microfluidic aqueous two-phase extraction coupled with an immunoassay

Immunoassays are fast and sensitive techniques for analyte quantification, and their use in point-of-care devices for medical, environmental, and food safety applications has potential benefits of cost, portability, and multiplexing. However, immunoassays are often affected by matrix interference effects, requiring the use of complex laboratory extraction and concentration procedures in order to achieve the required sensitivity. In this paper we propose an integrated microfluidic device for the simultaneous matrix clean-up, concentration and detection. This device consists of two modules in series, the first performing an aqueous two-phase extraction (ATPE) for matrix extraction and analyte pre-concentration, and the second an immunoassay for quantification. The model analyte was the mycotoxin ochratoxin A (OTA) in a wine matrix. Using this strategy, a limit of detection (LoD) of 0.26 ng mL(-1) was obtained for red wine spiked with OTA, well below the regulatory limit for OTA in wines of 2 ng mL(-1) set by the European Union. Furthermore, the linear response on the logarithmic concentration scale was observed to span 3 orders of magnitude (0.1-100 ng mL(-1)). These results are comparable to those obtained for the quantification of OTA in plain buffer without an integrated ATPE (LoD = 0.15 ng mL(-1)). The proposed method was also found to provide similar results for markedly different matrices, such as red and white wines. This novel approach based on aqueous two-phase systems can help the development of point-of-care devices that can directly deal with real samples in complex matrices without the need for extra extraction processes and equipment.

The effect of the surface functionalization and the electrolyte concentration on the electrical conductance of silica nanochannels

It is known that the conductance of nanochannels as a function of electrolyte concentration deviates from a linearly proportional relationship and approaches a value independent of the concentration as the electrolyte concentration is lowered. Most of the proposed models account for this behavior by considering a constant surface charge density and an ideal electrolyte solution. However, at low electrolyte concentrations, the ideal electrolyte approximation is no longer valid because the ions that result from the atmospheric carbon dioxide dissolution in water dominate the ionic concentration. In this paper, arrays of silica nanochannels were electrically characterized via conductance measurements. The conductance at low salt concentrations is modeled by a variable surface charge model that accounts for all ionic species in solution. This model was used to determine the variable surface charge of the bare silica nanochannels as well as of chemically modified nanochannels. The model correctly predicted the variation of the nanochannel conductance observed after silane (aminopropyldimethylethoxysilane) functionalization and single-strand DNA immobilization. Finally, pH modification of bulk KCl solutions was employed as an alternative method of changing the surface charge of silica nanochannels. Surface charge calculated from conductance measurements performed at different bulk pH values confirmed that the surface charge of the silica nanochannel walls is sensitive to the H(+) concentration.

Accupouncture for acute management and rehabilitation of traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) can be life threatening depending on the severity of the insult to the brain. It can also cause a range of debilitating sequelae which require cognitive, motor, communication, emotional, or behavioral rehabilitation of varying intensity and duration. A number of studies conducted and published in China have suggested that acupuncture may be beneficial in the acute treatment and rehabilitation of TBI. The aim of this paper was to determine the efficacy and safety of acupuncture in the acute management or rehabilitation (or both) of patients with a TBI, including cognitive, neurological, motor, communication, emotional, or behavioral complications, or a combination of such complications.

METHODS

We searched the Cochrane Injuries Group Specialised Register, Cochrane Central Register of Controlled Trials 2008, Issue 2 (The Cochrane Library), MEDLINE, EMBASE, CINAHL, AMED, PsycINFO and others. We also searched the Chinese Acupuncture Studies Register, the Studies Register of the Cochrane Complementary Medicine Field, NCCAM, and NIH Clinical Studies Database. Three major Mainland Chinese academic literature databases (CNKI, VIP and Wang Fang Data) were also searched using keywords in simplified Chinese. Searches were completed in December 2009. Randomized controlled studies evaluating different variants of acupuncture and involving participants of any age who had suffered a TBI. Included trials compared acupuncture with placebo or sham treatment, or acupuncture plus other treatments compared with the same other treatments.We excluded trials that only compared different variants of acupuncture or compared acupuncture alone against other treatments alone, as they did not yield the net effect of acupuncture. Two review authors identified potential articles from the literature search and extracted data independently using a data extraction form. We performed methodological assessment of included studies using the Cochrane Collaboration's tool for assessing risk of bias. We were unable to perform quantitative data analysis due to insufficient included studies and available data.

RESULTS

Four RCTs, including 294 participants, reported outcomes specified by this review. Three investigated electro-acupuncture for TBI while one investigated acupuncture for acute TBI. The results seem to suggest that acupuncture is efficacious for these indications, however the low methodological quality of these studies renders the results questionable. No adverse effects of acupuncture were reported in any of the studies.

CONCLUSIONS

The low methodological quality of the included studies does not allow us to make conclusive judgments on the efficacy and safety of acupuncture in either the acute treatment and/or rehabilitation of TBI. Its beneficial role for these indications remains uncertain. Further research with high quality trials is required.

Covalent immobilization of DNA and hybridization on microchips by microsecond electric field pulses

Single square voltage pulses were used to enhance by 7 and 9 orders of magnitude the rate of covalent immobilization and hybridization, respectively, of single stranded DNA probes on a chemically functionalized thin film surface (silicon dioxide) using 2 mm size electrodes. These electrodes were scaled down to 20 μm. Photolithography was used to define the electrode voltage line, ground line, and functionalized thin-film area on a plastic substrate (polyimide). At all electrode dimensions, electric field-assisted DNA immobilization and hybridization can be achieved in the microsecond time scale, far faster than the 2 hr or 16 hr needed for immobilization and hybridization, respectively, without the electric field. Pulse conditions optimized with the large-size electrodes (2 mm) were used in the microelectrodes.

Time-of-Flight Measurements in a-Si:H Between Room Temperature and 130° C°

The drift mobility μd and the mobility-lifetime product μτ in undoped a-Si:H have been studied up to 130°C. The electron μde is temperature-activated with Eae = 0.13 to 0.16 eV. The electron (μτ)e increases with temperature T. For hole transport, we observe the transition from dispersive to non-dispersive transport with increasing T. The hole μdh is ∼ 1/100 of μde, and is activated with Eah = 0.34 to 0.48eV. The hole (μτ)h does not change much with T. A computer simulation demonstrates the high sensitivity of μd to the band tail width.

Heterogeneous immunoassays in microfluidic format using fluorescence detection with integrated amorphous silicon photodiodes

Miniaturization of immunoassays through microfluidic technology has the potential to decrease the time and the quantity of reactants required for analysis, together with the potential of achieving multiplexing and portability. A lab-on-chip system incorporating a thin-film amorphous silicon (a-Si:H) photodiode microfabricated on a glass substrate with a thin-film amorphous silicon-carbon alloy directly deposited above the photodiode and acting as a fluorescence filter is integrated with a polydimethylsiloxane-based microfluidic network for the direct detection of antibody-antigen molecular recognition reactions using fluorescence. The model immunoassay used consists of primary antibody adsorption to the microchannel walls followed by its recognition by a secondary antibody labeled with a fluorescent quantum-dot tag. The conditions for the flow-through analysis in the microfluidic format were defined and the total assay time was 30 min. Specific molecular recognition was quantitatively detected. The measurements made with the a-Si:H photodiode are consistent with that obtained with a fluorescence microscope and both show a linear dependence on the antibody concentration in the nanomolar-micromolar range.

Application of Thin-Film Micromachining for Large-Area Substrates

Surface micromachining is used with amorphous silicon, microcrystalline silicon, silicon nitride and aluminum films as structural materials to form bridge and cantilever structures. Low temperature processing (between 110 and 250 °C) allowed fabrication of structures and devices on glass substrates. Two processes involving different materials as the sacrificial layer are presented: silicon nitride and photoresist. The mechanical integrity of the fabricated structures is discussed. As examples of possible device applications of this technology, air-gap thin film transistors and the electrostatic actuation of bridges and cantilevers are presented.

Amorphous Silicon-Carbon alloys Deposited by Electron-Cyclotron Resonance PECVD

Hydrogenated amorphous silicon-carbon alloys are prepared using electron-cyclotron resonance (ECR) plasma-enhanced chemical-vapor deposition. Hydrogen is used as the excitation gas in the resonance chamber while silane and methane (or ethylene) are introduced in the main chamber. A minimum of 95% hydrogen dilution is used. The microwave power is kept constant at 150 W. The effect of the type of carbon source gas, silane to carbon source gas ratio, deposition pressure, substrate temperature and hydrogen dilution on the deposition rate, bandgap and Urbach energy are studied. The photoconductivity and the Urbach energy of the ECR-deposited films are compared to those prepared with glow discharge with the same bandgap.

Performance of Thin-Film Silicon MEMS Resonators in Vacuum

This paper reports on the fabrication and characterization of microelectromechanical bridge resonators on glass substrates using thin-film technology and surface micromachining. All the processing steps are performed at temperatures below 110°C. The microbridges consist of either a single layer of heavily doped n-type amorphous silicon (n+-a-Si:H) or bilayers of aluminum (Al) and intrinsic a-Si:H. The bridge is suspended over a gate electrode with a 1 μm air-gap. Applying a voltage between the bridge and an underlying Al gate electrode electrostatically actuates the microstructures. The resulting deflection is monitored optically. The resonance of the microbridges is measured in air and in vacuum. Resonance frequencies up to 70 MHz and quality factors up to 3000 are obtained at pressures below 1 Torr. The energy dissipation mechanisms of the resonators are discussed.

Thin film micro arrays with immobilized DNA for hybridization analysis

In this work, a procedure to immobilize DNA probes on a microarray patterned on a flexible plastic substrate is developed. The method involves the chemical activation of a thin film surface, the introduction of amine functionality via a silanization step, the coupling of an adequate crosslinker and finally the immobilization of the DNA probe. The response of different thin-film materials and plastic substrates to the immobilization procedure is discussed. The DNA probes immobilized in the patterned pixels were then allowed to hybridize with complementary target DNA labeled with a fluorescent molecule. A prototype array of thin film pixels of SiO2 functionalized by silanization deposited over a polyimide substrate is demonstrated.

The effect of the shape of single, sub-ms voltage pulses on the rates of surface immobilization and hybridization of DNA

Electric fields generated by single square and sinusoidal voltage pulses with amplitudes below 2 V were used to assist the covalent immobilization of single-stranded, thiolated DNA probes, onto a chemically functionalized SiO2 surface and to assist the specific hybridization of single-stranded DNA targets with immobilized complementary probes. The single-stranded immobilized DNA probes were either covalently immobilized (chemisorption) or electrostatically adsorbed (physisorption) to a chemically functionalized surface. Comparing the speed of electric field assisted immobilization and hybridization with the corresponding control reactions (without electric field), an increase of several orders of magnitude is observed, with the reaction timescaled down from 1 to 2 h to a range between 100 ns and 1 ms. The influence of the shape of the voltage pulse (square versus sinusoidal) and its duration were studied for both immobilization and hybridization reactions. The results show that pulsed electric fields are a useful tool to achieve temporal and spatial control of surface immobilization and hybridization reactions of DNA.

Concomitant developmental dental anomalies in Chinese children with dens evaginatus

AIM

To determine the prevalence of concomitant developmental dental anomalies in a group of Chinese children with dens evaginatus.

METHODS

The dental records and orthopantomograms of 10-15 year old children and adolescents who had been diagnosed with dens evaginatus in a school dental clinic were reviewed retrospectively.

RESULTS

Four hundred and forty-eight of 7102 (6.3%) children were found to have dens evaginatus. Concomitant developmental dental anomalies were found in 77 children (17.2%). The most commonly seen dental anomalies in the study population were hypodontia, hyperdontia, microdontic maxillary lateral incisor, and dental impaction. The prevalence of these anomalies did not differ significantly to that found in the general Chinese population. When analysed separately, however, the prevalence of supernumerary premolars was found to be higher in children with dens evaginatus than in the general population, and the difference was statistically significant (P < 0.01).

CONCLUSION

Supernumerary premolars appeared to be more prevalent in Chinese children with dens evaginatus than in the general population. There may be an association of supernumerary premolars with dens evaginatus in this study population.

Rickettsial infections and fever, Vientiane, Laos

Rickettsia spp. are an underrecognized cause of undifferentiated febrile illness.

Rickettsial diseases have not been described previously from Laos, but in a prospective study, acute rickettsial infection was identified as the cause of fever in 115 (27%) of 427 adults with negative blood cultures admitted to Mahosot Hospital in Vientiane, Laos. The organisms identified by serologic analysis were Orientia tsutsugamushi (14.8%), Rickettsia typhi (9.6%), and spotted fever group rickettsia (2.6% [8 R. helvetica, 1 R. felis, 1 R. conorii subsp. indica, and 1 Rickettsia "AT1"]). Patients with murine typhus had a lower frequency of peripheral lymphadenopathy than those with scrub typhus (3% vs. 46%, p<0.001). Rickettsioses are an underrecognized cause of undifferentiated febrile illnesses among adults in Laos. This finding has implications for the local empiric treatment of fever.

Single base mismatch detection by microsecond voltage pulses

A single square voltage pulse applied to metal electrodes underneath a silicon dioxide film upon which DNA probes are immobilized allows the discrimination of DNA targets with a single base mismatch during hybridization. Pulse duration, magnitude and slew rate of the voltage pulse are all key factors controlling the rates of electric field assisted hybridization. Although pulses with 1 V, lasting less than 1 ms and with a rise/fall times of 4.5 ns led to maximum hybridization of fully complementary strands, lack of stringency did not allow the discrimination of single base mismatches. However, by choosing pulse conditions that are slightly off the optimum, the selectivity for discriminating single base mismatches could be improved up to a factor approximately 5 when the mismatch was in the middle of the strand and up to approximately 1.5 when the mismatch was on the 5'-end and. These results demonstrate that hybridization with the appropriate electric field pulse provides a new, site-specific, approach to the discrimination of single nucleotide polymorphisms in the sub-millisecond time scale, for addressable DNA microarrays.

Electric-field assisted immobilization and hybridization of DNA oligomers on thin-film microchips

Single, square voltage pulses in the microsecond timescale result in selective 5'-end covalent bonding (immobilization) of thiolated single-stranded (ss) DNA probes to a modified silicon dioxide flat surface and in specific hybridization of ssDNA targets to the immobilized probe. Immobilization and hybridization rates using microsecond voltage pulses at or below 1 V are at least 10(8) times faster than in the passive control reactions performed without electric field (E), and can be achieved with at least three differently functionalized thin-film surfaces on plastic or glass substrates. The systematic study of the effect of DNA probe and target concentrations, of DNA probe and target length, and the application of asymmetric pulses on E-assisted DNA immobilization and hybridization showed that: (1) the rapidly rising edge of the pulse is most critical to the E-assisted processes, but the duration of the pulse is also important; (2) E-assisted immobilization and hybridization can be performed with micrometre-sized pixels, proving the potential for use on microelectronic length scales, and the applied voltage can be scaled down together with the electrode spacing to as low as 25 mV; and (3) longer DNA chains reduce the yield in the E-assisted immobilization and hybridization because the density of physisorbed single-stranded DNA is reduced. The results show that the E-induced reactions can be used as a general method in DNA microarrays to produce high-density DNA chips (E-immobilization) and speed the microarray-based analysis (E-hybridization).

Immobilization and hybridization by single sub-millisecond electric field pulses, for pixel-addressed DNA microarrays

Single square voltage pulses applied to buried electrodes result in dramatic rate increases for (1) selective covalent bonding (immobilization) of single-stranded DNA (ssDNA) probes to a functionalized thin film SiO(2) surface on a plastic substrate and (2) hybridization of ssDNA to the immobilized probe. DNA immobilization and hybridization times are 100 ns and 10 micros, respectively, about 10(9) times faster than the corresponding passive reactions without electric field. Surface coverage is comparable. Duration, magnitude and slew rate of the voltage pulse are all key factors controlling the rates of ssDNA immobilization and hybridization. With rise times of 4.5 ns, pulses shorter than 1 ms and voltages below 1V are effective. The ssDNA adsorbed on the surface is reoriented by the rapidly changing electric field. This reduces steric barriers and speeds the immobilization and hybridization reactions. These results open the way for pixel-addressed microarrays driven by silicon microelectronics circuits.

An on-chip thin film photodetector for the quantification of DNA probes and targets in microarrays

A flat microdevice which incorporates a thin-film amorphous silicon (a-Si:H) photodetector with an upper layer of functionalized SiO2 is used to quantify the density of both immobilized and hybridized DNA oligonucleotides labeled with a fluorophore. The device is based on the photoconductivity of hydrogenated amorphous silicon in a coplanar electrode configuration. Excitation, with near UV/blue light, of a single-stranded DNA molecule tagged with the fluorophore 1-(3-(succinimidyloxycarbonyl)benzyl)-4-(5-(4-methoxyphenyl)oxazol-2-yl) pyridinium bromide (PyMPO), results in the emission of visible light. The emitted light is then converted into an electrical signal in the photodetector, thus allowing the optoelectronic detection of the DNA molecules. The detection limit of the present device is of the order of 1 x 10(12) molecules/cm2 and is limited by the efficiency of the filtering of the excitation light. A surface density of 33.5 +/- 4.0 pmol/cm2 was measured for DNA covalently immobilized to the functionalized SiO2 thin film and a surface density of 3.7 +/- 1.5 pmol/cm2 was measured for the complementary DNA hybridized to the bound DNA. The detection concept explored can enable on-chip electronic data acquisition, improving both the speed and the reliability of DNA microarrays.

Electrocardiographic and other cardiac anomalies in beta-glucuronidase-null mice corrected by nonablative neonatal marrow transplantation

Cardiovascular manifestations of lysosomal storage disease (LSD) are a significant health problem for affected patients. Infantile-onset cardiac disease, because of its rapid progression, is usually treated symptomatically. Therapy in older patients includes valve replacement and bone marrow (BM) transplantation, both of which are life threatening in the already debilitated patients. Enzyme replacement therapy has potential benefit but has not yet been demonstrated to provide long-term relief for cardiac disease. Here, we demonstrate prevention of severe cardiac manifestations in beta-glucuronidase (GUSB) null mice BM-transplanted i.v. as neonates without myeloablative pretreatment. The mice, a model of mucopolysaccharidosis type VII (MPSVII, Sly syndrome), develop progressive LSD unless provided with GUSB early in life. The BM recipients retained GUSB+ donor cells in the peripheral blood and heart until necropsy at > or = 11 months of age. The enzyme beta-hexosamindase increased in tissues of GUSB null MPSVII mice was reduced significantly (P = 0.001) in treated MPSVII hearts. Electrocardiography demonstrated normalization of heart rate, PR, PQ, and QRS intervals in BM recipients. Storage was markedly reduced in the stroma of heart valves, adventitial cells of the aortic root, perivascular and interstitial cells of the myocardium, and interstitial cells of the conduction tissue. Heart/body weight ratio normalized. The aortic root was still grossly distended, and the conductive myocytes retained storage, suggesting neither plays a major role in ECG normalization. We conclude that transplantation of MPSVII neonates without toxic intervention can prevent many of the cardiovascular manifestations of LSD.

Superiority of enoxaparin over heparin in combination with a GPIIb/IIIa receptor antagonist during coronary thrombolysis in dogs

It is known that a low-molecular-weight heparin (LMWH) is more effective than unfractionated heparin in unstable angina/non-Q-wave myocardial infarction (UA/NQMI) and the platelet GPIIb/IIIa receptors play an important role in acute myocardial infarction (AMI). Therefore, enoxaparin might have a similar advantage over heparin when used with a GPIIb/IIIa antagonist (RPR109891) in coronary thrombolysis. After induction of coronary thrombosis in anesthetized dogs, infusion of saline, enoxaparin, heparin, RPR109891, enoxaparin+RPR109891, or heparin+RPR109891 was initiated followed 15 min later by recombinant tissue plasminogen activator (rt-PA). The incidence of reperfusion in the enoxaparin+RPR109891- and the heparin+RPR109891-treated groups was similar, but time to reperfusion tended to be shorter for enoxaparin versus heparin. Only 43% of the vessels reoccluded in the enoxaparin+RPR109891 group, compared to 100% vessels in the heparin+RPR109891 group. Enoxaparin+RPR109891 maintained flow for a significantly longer time compared to saline, enoxaparin, heparin, and heparin+RPR109891. Enoxaparin+RPR109891 and heparin+RPR109891 increased the template bleeding time by 2- and 3-fold and activated partial thromboplastin time (APTT) by 1.3- and 3-fold, respectively. These data suggest that enoxaparin is more effective and potentially safer than heparin when combined with a GPIIb/IIIa receptor antagonist during rt-PA-induced coronary thrombolysis.

Pharmacological characterization of a novel factor Xa inhibitor, FXV673

FXV673 is a novel, potent, and selective factor Xa (FXa) inhibitor. FXV673 inhibited human, dog, and rabbit FXa with a K(i) of 0.52, 1.41, and 0.27 nM, respectively. FXV673 also displayed excellent specificity toward FXa relative to other serine proteases. It showed selectivity of more than 1000-fold over thrombin, activated protein C (aPC), plasmin, and tissue-plasminogen activator (t-PA). FXV673 prolonged plasma activated partial thromboplastin time (APTT) and prothrombin time (PT) in a dose-dependent fashion. In the APTT assays, the concentrations (microM) required for doubling coagulation time were 0.41 (human), 0.65 (monkey), 1.12 (dog), 0.25 (rabbit), and 0.80 (rat). The concentrations (microM) required in the PT assays were 1.1 (human), 1.32 (monkey), 2.31 (dog), 0.92 (rabbit), and 1.69 (rat). A coupled-enzyme assay was performed to measure thrombin activity following prothrombinase conversion of prothrombin to thrombin. FXV673 showed IC(50)s of 1.38 and 2.55 nM, respectively, when artificial phosphatidylserine/phosphatidylcholine (PS/PC) liposomes or fresh platelets were used as the phospholipid source for prothrombinase complex formation. It was demonstrated that FXV673 could inhibit further thrombin generation in the prothrombinase complex using PS/PC liposomes. FXV673 dose-dependently prolonged the time to vessel occlusion and inhibited thrombus formation in well-characterized canine models of thrombosis. Interspecies extrapolation (approximately 2.5-fold higher sensitivity for FXa inhibition in human than in dog) suggested that 100 ng/ml of FXV673 would be an effective plasma concentration for clinical studies. Currently FXV673 is undergoing clinical studies to be developed as an antithrombotic agent.

Role of short-term inhibition of factor Xa by FXV673 in arterial passivation: a study in a chronic model of thrombosis in conscious dogs

Factor Xa (fXa) plays a pivotal role in the activation of the coagulation system during thrombosis, but, unlike GPIIb/IIIa receptor antagonists, the role of fXa inhibition in arterial passivation is not well defined. We compared the long-term antithrombotic efficacy of a direct fXa inhibitor, FXV673, and heparin after short-term infusion in conscious dogs. Dogs were instrumented surgically to induce carotid artery thrombosis by electrolytic injury. On day 1, dogs received a 3-h infusion of placebo (n = 10), FXV673 (100 microg/kg + 10 microg/kg/min, n = 7), or heparin (60 U/kg + 0.7 U/kg/min, n 7). Injury (100 microA) was initiated concomitantly for 1 h. The procedure was repeated on day 2 with injury of 200 microA for 3 h. Carotid artery blood flow (CBF) and coagulation parameters were monitored continuously for 3 h on days 1 and 2 and for 30 min on days 3, 4, and 5. On day 1 at 3 h, CBF in the placebo-treated group was 26% of baseline with 70% incidence of occlusion. None of the vessels occluded in the heparin and FXV673 groups; however, the CBF was significantly higher in the FXV673 group (92+/-8 ml/min versus 39+/-12 ml/min). Before injury on day 2, CBF recovered in all groups to 71-89% of baseline. After the second injury, all vessels in the placebo-treated group progressed to complete occlusion by 3 h. CBF was significantly higher in FXV673 group compared with heparin throughout the 3-h period. On days 3, 4, and 5 the placebo-treated vessels remained occluded, but the CBF in the heparin group was 33+/-20 ml/min, 55+/-11 ml/min and 68+/-12 ml/min, respectively, compared with 84+/-10 ml/min, 98+/-7 ml/min, and 99+/-10 ml/min in the FXV673 group. The arterial thrombus mass was significantly lower in FXV673 group (13+/-4 mg) compared with placebo (103+/-10 mg) and heparin (44+/-11 mg). In summary, these data demonstrate that short-term infusion of FXV673 was associated with long-term efficacy that was superior to standard heparin and underscore the role of direct fXa inhibition in arterial passivation.

Antithrombotic efficacy of a novel factor Xa inhibitor, FXV673, in a canine model of coronary artery thrombolysis

We compared the antithrombotic efficacy of a potent factor Xa inhibitor, FXV673, to heparin and RPR109891, a GPIIb/IIIa antagonist, when used as adjunctive therapy in a canine model of rt-PA-induced coronary thrombolysis. Thrombus formation was induced by electrolytic injury to stenosed coronary artery. After thrombotic occlusion, a 135 min infusion of saline (n=8), FXV673 (10, 30 or 100 microg kg(-1)+1, 3, or 10 microg kg(-1) min(-1), respectively; n=8 per dose), heparin (60 u kg(-1)+0.7 u kg(-1) min(-1), n=8), or RPR109891 (30 microg kg(-1)+0.45 microg kg(-1) min(-1), n=8), was initiated. Aspirin (5 mg kg(-1), i.v.) was administered to all animals. Fifteen minutes after the start of drug infusion, rt-PA was administered (100 microg kg(-1)+20 microg kg(-1) min(-1) for 60 min). The incidence of reperfusion in the high dose FXV673 (8/8, 100%) was significantly greater than that in the heparin group (4/8, 50%), with a trend to faster reperfusion (23+/-5 min for FXV673 versus 41+/-11 min for heparin). Only 2/8 (25%) of the vessels reoccluded in the high dose FXV673 group, compared to 4/4 (100%) and 5/5 (100%) vessels in the heparin and RPR109891 groups, respectively (P<0.05). Throughout the protocol, blood flow was higher in the FXV673 treated group compared to other groups. FXV673 enhanced vessel patency in a dose-dependent manner. Compared to vehicle and heparin groups, the thrombus mass was decreased by 60% in the high dose FXV673. FXV673, heparin and RPR109891 increased the bleeding time by 2.7, 1.7 and 4 fold, and APTT by 2.8, 2.7 and 1.2 fold, respectively. In conclusion, FXV673 is more effective than heparin and at least as effective as RPR109891 when used as an adjunct during rt-PA-induced coronary thrombolysis.