81 results about "Microdialysis" patented technology

A self-calibrating monitoring system based on microdialysis for measurement of a body analyte is disclosed. In one embodiment, perfusate containing a known concentration of body analyte is mixed with an enzyme solution after passing through a microdialysis needle and instead of passing through the microdialysis needle to measure the body analyte and to calibrate the analysis chamber that measures the body analyte.

A system, including catheter apparatus, and related method for performing site specific therapy. The catheter apparatus can include one or more semipermeable microcatheters for use in performing site specific microdialysis. The system and method are particularly suited for use in addressing cerebral edema by affecting the osmolar relationship between fluids making up the brain tissue. Also disclosed is an apparatus having a delivery / recovery mechanism in the form of a pump reservoir and one or more catheters in the form of semipermeable microcatheters, for use in delivering and / or recovering fluid to and / or from a tissue site or for performing tissue engineering outside of the body. The apparatus can be used in a method to perform site specific microtherapy, including for the treatment of avascular necrosis, compartment syndrome, cerebral edema, and to improve skin flap survival in the course of reconstructive surgery.

A metabolite monitoring system comprising a microdialysis probe including a semi-permeable membrane and a probe flow path passing from an inlet through a sensing volume adjacent to said semi-permeable membrane to an outlet, a fluid delivery device for delivering dialysate to said inlet; and a metabolite monitoring system associated with said outlet for monitoring a concentration of at least one metabolite in said dialysate from said microdialysis probe, wherein said fluid delivery device is configured to deliver a pulsed flow of said dialysate to said inlet.

The invention relates to a droplet-based digital microdialysis method that utilizes discrete perfusate droplets marched through a microchannel in an intermittent manner. The droplets sequentially reside on a microdialysis membrane that is in contact with the test fluid, e.g., fluid in an extracellular space. The droplets remain stationary at the membrane site for a period of time for rapid equilibration with the test fluid, and is then marched to an outlet port for processing. The invention further relates to microdialysis probes and methods based on the droplet-based digital microdialysis.

The present invention concerns a pump for flow rates from about 1 to 1000 nl / min in which liquid transport takes place by evaporation of a transport liquid through a wettable membrane. The pumps according to the invention are particularly suitable for applications in the field of medical diagnostics such as microdialysis or ultrafiltration.

The invention provides a method for testing plant endogenous hormones, comprises the following steps of: carrying out microdialysis sampling on a plant body; carrying out sample injection on the acquired dialyzate on a high-performance liquid chromatograph; and simultaneously separating and determining four main plant endogenous hormones: gibberellic acid (GA), cytokinin (6-BA), indolylacetic acid (IAA) and abscisic acid (ABA). Compared with the traditional method for testing the plant endogenous hormones, the invention realizes the intravital test on the plant endogenous hormones and can reduce the damage to the plant body to maximum extent; in addition, the invention can simply and conveniently extract samples, has simple operation, can really reflect the change of the content of the endogenous hormones in the plant body in the vital movement progress and realize the real-time, intravital and on-line test on the plant endogenous hormones.

A system, including catheter apparatus, and related method for performing site specific therapy. The catheter apparatus can include one or more semipermeable microcatheters for use in performing site specific microdialysis. The system and method are particularly suited for use in addressing cerebral edema by affecting the osmolar relationship between fluids making up the brain tissue.Also disclosed is an apparatus having a delivery / recovery mechanism in the form of a pump reservoir and one or more catheters in the form of semipermeable microcatheters, for use in delivering and / or recovering fluid to and / or from a tissue site or for performing tissue engineering outside of the body. The apparatus can be used in a method to perform site specific microtherapy, including for the treatment of avascular necrosis, compartment syndrome, cerebral edema, and to improve skin flap survival in the course of reconstructive surgery.

An integrative microdialysis and chip-based electrophoresis system and analytical method using the same are disclosed. The system combines the microdialysis probe sampling technique and continuous pressure flow feeding coupled with chip-based electrophoresis analysis. It is capable of performing online sampling as well as rapid and continuous monitoring and analysis of biological samples. The system offers the advantages of real-time on-chip dye labeling, simple apparatus setup and easy operation.

A metabolite monitoring system comprising a microdialysis probe including a semi-permeable membrane and a probe flow path passing from an inlet through a sensing volume adjacent to said semi-permeable membrane to an outlet, a fluid delivery device for delivering dialysate to said inlet; and a metabolite monitoring system associated with said outlet for monitoring a concentration of at least one metabolite in said dialysate from said microdialysis probe, wherein said fluid delivery device is configured to deliver a pulsed flow of said dialysate to said inlet.

It has been surprisingly found that very accurate measurements of mass transfer can be made rapidly by permitting diffusion of an agent desired to be measured into a small, known volume of receiver or out of a known volume of donor, then rapidly pumping or flushing (“pulsing”) the receiver with a known volume of fluid. More specifically, a novel method of transferring small quantities of a contained material (either dissolved or suspended) between two media, based on such pulsing, hereinafter called pulsatile microdialysis (PMD), is disclosed. In a preferred embodiment, one medium (the dialysate) is inside a small, permeable tube (microdialysis probe window) and the other (external medium) is outside. The transfer of material between the two media can be utilized, for example, to sample drug concentrations in the external medium, or the release of drugs from systems within the dialysate, or for other measurements as disclosed herein. In PMD, a dialysate fluid is pumped into a microdialysis probe window, allowed to occupy the probe window while at rest for some resting time, and then flushed at a high rate out as a single pulse. A model that is based on a Fick's Laws was solved, and equations were derived to calculate the effects of various experimental parameters. The models were verified against experimental data using methazolamide, warfarin and benzocaine as test drugs. The data followed the mathematical models. For cases in which the concentration of free drug in the medium outside the probe was constant or changed very slowly, the concentration calibration plots were linear. In simulated first order uptake studies, the PMD and direct donor sampling data were in nearly exact agreement with the theoretical values of k=0.09 min−1. In another experiment, the free concentration of warfarin sodium in the medium outside the probe was made to decline rapidly in a known first order manner, with rate constants as high as 0.077 sec−1. The concentration in the external medium calculated from the PMD data was in nearly exact agreement with the known concentration at various times, and the experimental rate constants were in nearly exact agreement with the theoretical rate constants. For binding of methazolamide to activated charcoal, and for the binding of sodium warfarin to bovine serum albumin, PMD was able to generate sufficient data points to accurately characterize the rapid initial binding. This invention demonstrates that PMD is an accurate method of sampling drug concentrations and measuring rates and extents of a number of processes, including protein binding, adsorption to binding agents such as activated charcoal, release from microemulsion drug delivery systems, and the determination of drug diffusion coefficients, and for various other purposes which will occur to those skilled in the art. Compared to known methods such as traditional (continuous) microdialysis, the present invention offers the ability to sample more frequently, and over much shorter time intervals, thereby accurately obtaining data not heretofore available.

Implantable self-calibrating biosensor Subcutaneously or intracorporeally implantable biosensor, characterized by a closed microfluidic circuit with calibrating fluids, which communicates by a backward micro-dialysis logic with the exterior of said circuit, an open and in contact with the tissues and the interstitial fluid working electrode, for its self-calibration. One or more working electrodes may be positioned inside openable boxes from EAP, and be opened for the duration of the measurement and closed immediately after, succeeding one another in the measurement, as their sensitivity is diminished.

The invention relates to the technical field of medicines, and concretely relates to a blood dialysate detection method, and an application thereof in the pharmacokinetics-pharmacodynamics of a pulseactivating injection. The method comprises the following steps: preparing a conscious rat in-vivo microdialysis sampling device collected blood dialysate, analyzing the drug concentration of active ingredients in the blood dialysate by high performance liquid chromatography-triple quadrupole mass spectrography, and detecting the drug effect index NO in the blood dialysate by high performance liquid chromatography-fluorescence detection technique. A conscious rat in vivo microdialysis technique adopted in the invention overcomes the influences of animal anesthesia and blood loss on the pharmacokinetic and pharmacodynamic behaviors, is successfully used in the studying of the plasma concentration-time and drug effect-time relationships of the pulse activating injection against rat myocardialischemia, and can be used to establish a pharmacokinetic-pharmacodynamic combination model. A study result shows that when an appropriate blood endogenous biomarker is selected as a drug effect index, the conscious animal in vivo microdialysis sampling technique becomes an ideal tool for pharmacokinetic-pharmacodynamic combination studying.

Methods and devices for delivering an agent to a solid tissue in vivo for assessment of efficacy are described. One method involves withdrawing of a needle from and injecting of the agent into the solid tissue; another method involves delivering the agent using a plurality of microdialysis probes to a solid tissue.

Very accurate measurements of mass transfer can be made rapidly by permitting diffusion of an agent desired to be measured into or out of a small, very precisely known volume of a microdialysis probe, then rapidly pumping or flushing (“pulsing”) the probe with a known volume of fluid as a single pulse. The diffusion and pulsing may be repeated. The method, hereinafter called pulsatile microdialysis (PMD) to distinguish it from prior art continuous flow microdialysis, is useful for measurements in a number of processes, including protein binding, adsorption to binding agents such as activated charcoal, release from microemulsion drug delivery systems, determination of drug diffusion coefficients and concentrations, and for various other purposes.The method is based on mathematical manipulation of Fick's Laws. Resulting equations were verified against experimental data using methazolamide, warfarin and benzocaine as test drugs.

The invention discloses a microdialysis probe capable of carrying out photogenetic stimulation. The probe comprises a probe shell, a limiting block and an optical fiber connector, the head of the probe shell is connected with a limiting block, the optical fiber connector is combined with the limiting block, the three structures form a main body structure of the probe, an optical fiber module and adialysis module are combined, two operations of optical genetic stimulation and micro dialysis are synchronously carried out, and molecular level change caused after specific neurons are activated byoptical waves can be synchronously detected in real time; the optical fiber can be inserted into a target brain area only when photostimulation and microdialysis operations are carried out, so that neuron damage and tissue reaction caused by a traditional method of placing the optical fiber and the brain for a long time can be avoided, and a long-term tracking experiment is facilitated. The microdialysis probe is used in the field of biomedical instruments.