Showing papers by "University of Texas System published in 2000"

Drug releasing biodegradable fiber implant

Abstract: The invention provides tissue engineering compositions and methods wherein three-dimensional matrices for growing cells are prepared for in vitro and in vivo use. The matrices comprise biodegradable polymer fibers capable of the controlled delivery of therapeutic agents. The spatial and temporal distribution of released therapeutic agents is controlled by use of defined nonhomogeneous patterns of therapeutic agents in the matrices.

Step and flash imprint lithography

Abstract: A method of forming a relief image in a structure comprising a substrate and a transfer layer formed thereon comprises covering the transfer layer with a polymerizable fluid composition, and then contacting the polymerizable fluid composition with a mold having a relief structure formed therein such that the polymerizable fluid composition fills the relief structure in the mold. The polymerizable fluid composition is subjected to conditions to polymerize polymerizable fluid composition and form a solidified polymeric material therefrom on the transfer layer. The mold is then separated from the solid polymeric material such that a replica of the relief structure in the mold is formed in the solidified polymeric material; and the transfer layer and the solidified polymeric material are subjected to an environment to selectively etch the transfer layer relative to the solidified polymeric material such that a relief image is formed in the transfer layer.

Method and apparatus for programmable fluidic processing

Abstract: A method and apparatus for microfluidic processing by programmably manipulating a packet. A material is introduced onto a reaction surface and compartmentalized to form a packet. A position of the packet is sensed with a position sensor. A programmable manipulation force is applied to the packet at the position. The programmable manipulation force is adjustable according to packet position by a controller. The packet is programmably moved according to the programmable manipulation force along arbitrarily chosen paths.

Woven intravascular devices and methods for making the same and apparatus for delivery of the same

Abstract: Self-expandable, woven intravascular devices for use as stents (both straight and tapered), filters (both temporary and permanent) and occluders for insertion and implantation into a variety of anatomical structures. The devices may be formed from shape memory metals such as nitinol. The devices may also be formed from biodegradable materials. Delivery systems for the devices include two hollow tubes that operate coaxially. A device is secured to the tubes prior to the implantation and delivery of the device by securing one end of the device to the outside of the inner tube and by securing the other end of the device to the outside of the outer tube. The stents may be partially or completely covered by graft materials, but may also be bare. The devices may be formed from a single wire. The devices may be formed by either hand or machine weaving. The devices may be created by bending shape memory wires around tabs projecting from a template, and weaving the ends of the wires to create the body of the device such that the wires cross each other to form a plurality of angles, at least one of the angles being obtuse. The value of the obtuse angle may be increased by axially compressing the body.

Woven bifurcated and trifurcated stents and methods for making the same

Abstract: Bifurcated (10) and trifurcated (300) woven stents for insertion and delivery into a variety of anatomical structures, including the aortic-iliac bifurcation, the superior vena cava junction, and the inferior vena cava junction. The bifurcated stents (10) includes a first leg (30) formed from a first plurality of wires (40), a second leg (30) formed from a second plurality of wires (40), and a common body formed from the first and second pluralities of wires (40). The wires may be nitinol. Biodegradable filaments may also be utilized. The angles created between the crossed wires is preferably obtuse. The bifurcated stents (10) may be formed from as few as two wires. The stents may be formed using plain weaving effected either by hand or by machine.

A simple algorithm for homeomorphic surface reconstruction

Abstract: 1 Introduction The problem of computing a piecewise linear approximation to a surface from a set of sam- ple points on the surface has been a focus of research in solid modeling and graphics due to its many applications. The input to this sur- face reconstruction problem consists of the three dimensional coordinates of the sampled points. The crust algorithm of [1] reconstructs a surface with topological and geometric guarantees using the Voronoi diagram of the input point set. We present new observations that simplify both the algorithm and the proofs for the crust, and we give for the first time a proof that the crust is homeomorphic to the input surface. *Dept. of Computer Science, U. of Texas, Austin TX 78712. e-mail: amenta@cs.utexas.edu tDept, of Computer Science, U. of Texas, Austin, TX 78712. e-mail: sunghee@cs.utexas.edu SDept. of Computer and Information Science, Ohio State U., Columbus, OH 43210. e-mail: t amaldey¢ci s. ohio-state, edu §Dept. of Computer and Information Science, Ohio State U., Columbus, OH 43210. e-mail: leekha@cis, ohio-state, edu

Melatonin: Lowering the high price of free radicals

Abstract: The endogenous antioxidative defense system reduces molecular toxicity of oxygen and nitrogen-based reactive species. Melatonin is an efficient direct and indirect antioxidant. It detoxifies the highly reactive hydroxyl radical and neutralizes other toxic species, including singlet oxygen, hydrogen peroxide, nitric oxide, and peroxynitrite anion, and stimulates several antioxidative enzymes.

Low cost, self regulating heater for use in an in situ thermal desorption soil remediation system

Abstract: An in situ thermal desorption soil remediation system may be used to remove contamination from soil. Heat may be applied to the soil by metallic strip heaters that have large cross sectional areas as compared to conventional heater elements. The strip heaters may be made of stainless steel. Large cross sectional areas of the strip heaters allow for large areas of thermal contact between the strip heaters and the soil being treated. Casings may not be needed between the strip heaters and the soil. The operating temperature of the strip heaters is self-regulating. As the temperature of a strip heater increases, the electrical resistance of the strip heater also increases. The increase in resistance causes a decrease in the power dissipation of the strip heater. The decrease in power dissipation as temperature increases allows a steady state heater strip temperature to be attained during use.

Gastrointestinal electrical stimulation

Abstract: The present invention is directed to a method of regulating gastrointestinal action in a subject using a stimulatory electrode and a sensor to provide retrograde feedback control of electrical stimulation to the GI tract. The invention is further directed to a method for reducing weight in a subject, again using a stimulatory electrode and a sensor to provide retrograde feedback control of electrical stimulation to the stomach. The invention is further directed to a method of providing electrical field stimulation to a gastrointestinal organ, as well as a method of providing an electrical potential gradient in a gastrointestinal organ. Further provided is a method of stimulating the vagus nerve of a subject. Additionally provided is a method of placing a device in the gastrointestinal tract or wall of a subject from the exterior of the subject, using a needle to insert the device.

Antibody compositions for selectively inhibiting VEGF

Abstract: Disclosed are antibodies that specifically inhibit VEGF binding to only one (VEGFR2) of the two VEGF receptors The antibodies effectively inhibit angiogenesis and induce tumor regression, and yet have improved safety due to their specificity The present invention thus provides new antibody-based compositions, methods and combined protocols for treating cancer and other angiogenic diseases Advantageous immunoconjugate and prodrug compositions and methods using the new VEGF-specific antibodies are also provided

Method and apparatus for fractionation using conventional dielectrophoresis and field flow fractionation

Abstract: Methods and apparatus for discriminating matter in a chamber having an inlet port and an outlet port utilizing dielectrophoresis and field flow fractionation. A carrier medium is introduced into the inlet port and is directed from the inlet port to the outlet port according to a velocity profile. A programmed voltage signal is applied to an electrode element coupled to the chamber to form a dielectrophoretic force on the matter. The dielectrophoretic force is balanced with a gravitational force to displace the matter to positions within said velocity profile in the carrier medium to discriminate the matter. A chamber having a top and bottom outlet port may be utilized to withdraw a first portion of a carrier medium from the top outlet port at a first, controllable fluid flow rate and to withdraw a second portion of the carrier medium from the bottom outlet port at a second, controllable fluid flow rate.

High precision orientation alignment and gap control stages for imprint lithography processes

Abstract: Processes and associated devices for high precision positioning of a template and substrate during imprint lithography includes a calibration system with a course calibration stage and a fine orientation stage capable of maintaining a uniform gap between the template and substrate. The fine orientation stage includes a pair of flexure members having flexure joints for motion about a pivot point intersected by first and second orientation axes. Actuators lengthen or shorten to expand or contract the flexure members. Separation of the template is achieved using a peel-and-pull method that avoids destruction of imprinted features from the substrate.

A declotting method and apparatus

Abstract: A declotting apparatus includes a catheter, a member positioned within the catheter, and a plurality of deformable members. The plurality of members bow and compress as the catheter slides relative to the member so that a site may be declotted. In another embodiment, a declotting apparatus includes a first and second catheter, a guidewire, a deformable jacket, and a liner. The deformable jacket expands and contract as the first catheter slides relative to the second catheter so that a site may be declotted. The guidewire facilitates navigation, and the liner prevents material from entering the apparatus.

Optoacoustic monitoring of blood oxygenation

Abstract: An optoacoustic apparatus is disclosed which includes a radiation source of pulsed radiation and a probe having a front face to be placed in close proximity to or in contact with a tissue site of an animal body. The probe further includes a plurality of optical fibers terminating at the surface of the front face of the probe and connected at their other end to a pulsed laser. The front face of the probe also has mounted therein or thereon a transducer for detecting an acoustic response from blood in the tissue site to the radiation pulses connected to a processing unit which converts the transducer signal into a measure of venous blood oxygenation.

Methods for noninvasive analyte sensing

Abstract: Methods for measuring analyte concentration within a tissue using optical coherence tomography (OCT). Radiation is generated, and a first portion of the radiation is directed to the tissue to generate backscattered radiation. A second portion of the radiation is directed to a reflector to generate reference radiation. The backscattered radiation and the reference radiation is detected to produce an interference signal. The analyte concentration is calculated using the interference signal.

Simulation of the pre-reversal enhancement in the low latitude vertical ion drifts

Abstract: Low latitude F region ion motions exhibit strong seasonal and solar cycle dependences. The pre-reversal enhancement (PRE) in the vertical ion drifts is a particularly well-known low latitude electrodynamic feature, exhibited as a sharp upward spike in the velocity shortly after local sunset, which remains poorly understood theoretically. The PRE has been successfully simulated for the first time by a general circulation model, the National Center for Atmospheric Research thermosphere/ionosphere/electrodynamic general circulation model (TIEGCM). The TIEGCM reproduces the zonal and vertical plasma drifts for equinox, June, and December for low, medium, and high solar activity. The crucial parameter in the model to produce the PRE is the nighttime E region electron densities: densities ≥ 104 cm−3 preclude the PRE development by short-circuiting the F region dynamo. The E region semidiurnal 2,2 tidal wave largely determines the magnitude and phase of the daytime F region drifts.

Antibody conjugate methods for selectively inhibiting VEGF

Abstract: Disclosed are antibodies that specifically inhibit VEGF binding to only one (VEGFR2) of the two VEGF receptors. The antibodies effectively inhibit angiogenesis and induce tumor regression, and yet have improved safety due to their specificity. The present invention thus provides new antibody-based compositions, methods and combined protocols for treating cancer and other angiogenic diseases. Advantageous immunoconjugate and prodrug compositions.

Method and apparatus for the delivery of samples to a chemical sensor array

Abstract: A system for the rapid characterization of multi-analyte fluids, in one embodiment, includes a light source, a sensor array, and a detector. The sensor array is formed from a supporting member into which a plurality of cavities may be formed. A series of chemically sensitive particles are, in one embodiment positioned within the cavities. The particles may be configured to produce a signal when a receptor coupled to the particle interacts with the analyte. Using pattern recognition techniques, the analytes within a multi-analyte fluid may be characterized.

Functional and oncological outcome of acetabular reconstruction for the treatment of metastatic disease.

Abstract: Background: Metastatic disease of the acetabulum can be painful and disabling. Operative intervention is indicated for patients who fail to respond adequately to nonoperative treatment. We evaluated the functional and oncological outcome of acetabular reconstruction after curettage for the treatment of refractory symptomatic acetabular metastases. Methods: Fifty-five patients with metastatic disease of the acetabulum were treated with operative acetabular reconstruction combined with a total hip replacement. The most common primary tumor was carcinoma of the breast (eighteen patients), followed by carcinoma of the kidney (seven patients) and carcinoma of the prostate (seven patients). Forty (73 percent) of the patients presented with multiple skeletal metastases, and eighteen (33 percent) had associated visceral metastases. Twenty-eight (51 percent) had severe pain requiring continuous use of narcotics, twenty-four (44 percent) had moderate pain requiring periodic use of narcotics, and the remaining three (5 percent) had mild pain requiring use of non-narcotic analgesics. Eighteen (33 percent) of the patients could not walk, twenty-three (42 percent) needed a walker or crutches, twelve (22 percent) used a single cane, and two (4 percent) walked without assistive devices. Intralesional curettage of the tumor was performed in all of the patients. Fifty-four of the hips were reconstructed with a protrusio cup and one, with a hemipelvis endoprosthesis. Large defects were reinforced with cement and pin or screw fixation (the modified Harrington technique), which allowed transmission of weight-bearing forces to the remaining intact pelvis. Thirty-six acetabular reconstructions were performed with antegrade pins or cannulated screws; fifteen, with long retrograde screws; and four, with cement. Results: The median period of survival was nine months. Patients with visceral metastases had a median period of survival of three months compared with twelve months for patients without visceral metastases (p < 0.001). Patients with breast cancer presented later in the disease process (p < 0.004) and lived longer than did those with other carcinomas (p < 0.004). Forty-five patients were evaluated three months after reconstruction. Thirty-four (76 percent) of them had relief of pain as determined by decreased use of narcotics. Nine of the eighteen patients who could not walk preoperatively regained the ability to walk. Fourteen of the seventeen patients who originally were able to walk in the community retained that ability. Thirty-three patients were available for evaluation at six months. Twenty-five (76 percent) still had relief of pain, and nineteen (58 percent) were able to walk and function in the community. Overall, fourteen (25 percent) of the fifty-five patients had moderate local progression of the disease, and five of these patients had failure of the fixation. Fourteen early complications developed in twelve (22 percent) of the patients. One patient (2 percent) died perioperatively. Conclusions: Patients who have acetabular metastases that are refractory to radiation and chemotherapy have a short life expectancy. The early, gratifying results of reconstruction validate the role of operative treatment as a short-term palliative procedure. Protrusio acetabular cups presumably compensate for deficiencies of the medial wall, while cement and pin fixation can be used effectively to reconstruct large defects in the acetabular column and dome. The low rate of fixation failure supports the biomechanical principles of the reconstruction. Generally, the reconstructions are sufficiently durable to exceed the life expectancy of the patients.

Avalanche photodiodes with an impact-ionization-engineered multiplication region

Abstract: We demonstrate an impact-ionization-engineered structure for the multiplication region of avalanche photodiodes. By enhancing the control of the impact-ionization position, the structure achieved high gain, low dark current, and very low noise.

Redox signaling: globalization of gene expression.

Abstract: Here we show that the extent of electron flow through the cbb3 oxidase of Rhodobacter sphaeroides is inversely related to the expression levels of those photosynthesis genes that are under control of the PrrBA two-component activation system: the greater the electron flow, the stronger the inhibitory signal generated by the cbb3 oxidase to repress photosynthesis gene expression. Using site-directed mutagenesis, we show that intramolecular electron transfer within the cbb3 oxidase is involved in signal generation and transduction and this signal does not directly involve the intervention of molecular oxygen. In addition to the cbb3 oxidase, the redox state of the quinone pool controls the transcription rate of the puc operon via the AppA–PpsR antirepressor–repressor system. Together, these interacting regulatory circuits are depicted in a model that permits us to understand the regulation by oxygen and light of photosynthesis gene expression in R.sphaeroides.

Detection system based on an analyte reactive particle

Abstract: A system for the rapid characterization of multi-analyte fluids, in one embodiment, includes a light source, a sensor array, and a detector. The sensor array is formed from a supporting member into which a plurality of cavities may be formed. A series of chemically sensitive particles are, in one embodiment positioned within the cavities. The particles may be configured to produce a signal when a receptor coupled to the particle interacts with the analyte. Using pattern recognition techniques, the analytes within a multi-analyte fluid may be characterized.

Increased levels of oxidatively damaged DNA induced by chromium(III) and H2O2: protection by melatonin and related molecules

Abstract: Chromium (Cr) compounds are known occupational and environmental carcinogens. This trace element is found in the workplace primarily in the valence forms Cr(III) and Cr(VI). Cr(III), which was thought originally to be relatively nontoxic, was recently found to be more reactive toward purified DNA than was chromium(VI). Herein, we examined the ability of Cr(III) to induce oxidative DNA damage by measuring the formation of 8-hydroxydeoxyguanosine (8-OH-dG) in purified calf thymus DNA incubated with CrCl3 plus H2O2. In this system we observed that the Cr(III)-induced formation of 8-OH-dG in isolated DNA was both dose- and time-dependent. When melatonin and related molecules, including 6-methoxy-1,2,3,4-tetrahydro-beta-carboline (pinoline), N-acetylserotonin, 6-hydroxymelatonin and indole-3-propionic acid, were co-incubated with CrCl3 plus H2O2, the accumulations of 8-OH-dG in DNA samples were markedly inhibited in a concentration-dependent manner. The concentrations of each indole required to reduce DNA damage by 50%, i.e. the IC50 values, were 0.48, 0.51, 0.88, 1.00 and 3.08 microM for pinoline, melatonin, N-acetylserotonin, 6-hydroxymelatonin and indole-3-propionic acid, respectively. These results suggest that one of the mechanisms by which Cr(III) may induce cancer is via Fenton-type reactions which generate the hydroxyl radical (*OH). The findings also indicate that the protective effects of melatonin and related molecules against Cr(III)-induced carcinogenesis relate to their direct *OH scavenging ability which thereby reduces the formation of the damaged DNA product, 8-OH-dG.

Percutaneous implantation of partially covered stents in aneurysmally dilated arterial segments with subsequent embolization and obliteration of the aneurysm cavity

Abstract: A low profile, abdominal aortic aneurysm exclusion device with iliac vessel extensions. A sectional, bifurcated stent forms part of an endoluminal prosthesis to eliminate or reduce the risk of rupture of aortic aneurysms. An apparatus and a method for introducing the bifurcated stent in sections into the vasculature and assembling the sections in situ to form a “scaffold” for introduction of material to re-endothelialize and/or occlude the aneurysm cavity. After trans-stent embolization of the aneurysm cavity with thrombogenic material, laminar flow stimulates endothelialization of the stent lumen. Subsequent organization and fibrosis of the persistent thrombus reinforces the wire-mesh or etched metal tubular scaffold comprising the stent and serves to stabilize and shrink the aneurysm. A single stent deployed with the same method may be used in non-bifurcated vessels.

Injectivity Decline in Water-Injection Wells: An Offshore Gulf of Mexico Case Study

Abstract: Injectivity decline in water injection wells can have a large impact on the economic feasibility of offshore water disposal operations. A case study is presented for an offshore Gulf of Mexico water injection project. Data are presented for five typical offshore wells for which a rapid decline in injectivity was observed due to water injection. The wells were successfully acidized every few months over a period of two years. An analysis of the data indicates that in injection wells that are not fractured, such declines in injectivity may be expected even for relatively clean injection water. A comparison of the different completion types indicates that both open hole and perforated completions would have yielded similar results. Cleaner water would have improved the situation but at a substantial cost. Fracturing the injection wells appears to be the only plausible way of substantially increasing the half life of such injectors. In cases where reservoir conditions dictate that the wells not be fractured, the economics of periodic stimulation versus the cost of installing surface facilities for cleaning up the water should be evaluated using models for injectivity decline. What if simulations conducted to study the impact of different process parameters such as injected particle size and concentration, injection rate and reservoir properties were found to be a useful tool in specifying water quality requirements.

Combinatorial oligonucleotide pcr: a method for rapid, global expression analysis

Abstract: The present invention relates to a method for the detection of gene expression and analysis of both known and unknown genes. The invention is a highly sensitive, rapid and cost-effective means of monitoring gene expression, as well as for the analysis and quantitation of changes in gene expression for a defined set of genes and in response to a wide variety of events. It is an important feature of the present invention that no single molecular species of cDNA gives rise to more than one fragment in the colleciton of products which are subsequently amplified and representative of each expressed gene. This achievement is facilitated by immobilizing the cDNA prior to digesting and then digesting with sequentially with two frequently cutting enzymes. Linker oligomers are ligated to each cut site following the respective digestion. Primers, complementary to the oligomer sequence with an additional 3' variable sequence are used to amplify the fragments. Using and array of fragments theoritically facilitates the amplification of all of the possible messages in a given sample.

High mobility heterojunction transistor and method

Abstract: A heterojunction transistor with high mobility carriers in the channel region includes a source region and a drain region formed in a semiconductor body with the source region and the drain region comprising doped semiconductor alloys separated from the substrate by heterojunctions. A channel region is provided between the source region and the drain region comprising an undoped layer of an alloy of the semiconductor material and a deposited layer of material of the semiconductor body overlying the undoped layer. A gate electrode is formed on a gate oxide over the channel region. In fabricating the high mobility heterojunction transistor, the spaced source and drain regions are formed in the substrate by implanting dopant of conductivity type opposite to the substrate and a material in the alloy and then annealing the structure to form the alloy of the semiconductor material under the undoped layer.