Recent Patents on Biomedical Engineering (Discontinued) - Volume 1, Issue 3, 2008

In this paper, we review modern nonlinearity methods that can be used in preterm birth analysis. The nonlinear analysis of uterine contraction signals can provide information regarding physiological changes during the menstrual cycle and pregnancy. This information can be used both for preterm birth prediction and preterm labour control. Both the contractions in different topographic regions of the uterus and the time delays between uterine contractions are essentially nonlinear events, so we have suggested the most appropriate nonlinear dynamics methods and patents.

There has been a continuous effort for more than two decades to generate universal red blood cells that can be used for transfusion without the need of matching the blood type. Three distinct strategies are being explored so far to achieve this goal. These include (i) deletion of the antigenic determinants of the blood group antigens on the surface of RBC by enzymatic methods, (ii) masking of the antigens from the cognate antibodies by conjugating bulky polymers to RBC membrane proteins, and (iii) design of bioengineered RBCs for ex vivo production in which the expression of the group specific antigens has been specifically manipulated. This article evaluates and compares the merits as well as the potential limitations of these approaches as well as the useful patents in the field of generation of universal red blood cells.

In recent years, Nitinol producers and medical products have experienced an exponential growth, driven by advanced manufacturing techniques and the use of progressively less invasive medical procedures. Concurrently, new processing techniques have been developed to further enhance the valuable properties of Nitinol used in medical devices; recent patents on these techniques include changing the composition of nickel and titanium, alloying the nickel-titanium with other elements, improving melting practices, heat-treating the alloy, and mechanical processing of the alloy. For example, alloying the nickel-titanium with ternary elements may widen the superelastic temperature operating window, maximize/minimize the stress-strain hysteresis, and improve the radiopacity of a Nitinol intraluminal device comparable to that of a stainless steel device of the same strut pattern coated with a thin layer of gold. Limiting to less than 30% the final cold work step (after a full anneal, and before the shape-setting step) may improve the Nitinol fatigue lifetime of about 37%, the fatigue lifetime being a primary factor limiting the performances of Nitinol endoluminal prosthetic implants. Local selective and differential thermo-mechanical treatments have also been devised to achieve different physical properties in different portions of a Nitinol medical device in order to improve its performance under expected operating conditions.

There are a variety of novel patented devices available to treat functional mitral regurgitation. Aside from direct valve replacement or repair, devices that can be implanted through a minimally invasive approach tend to amend this disease via one of three techniques: edge-to-edge repair, annuloplasty, or left ventricular reshaping. Recent attention has been allocated towards development of prospective devices to enable percutaneous mitral valve replacement. Clinical implementation of these devices is contingent upon evidence to suggest that they meet safety and efficacy requirements. This review provides a brief description of patents relevant to some commercial devices that are currently undergoing clinical trials and other devices that are still under pre-clinical testing.

The advent of complex radiotherapy techniques has created new challenges for radiation dosimetry. Intensity modulated, stereotactic, conformal radiotherapy, radiosurgery and brachytherapy present a field where both spatial and quantitative accuracy become crucial to the success of the treatment. Methods for true 3-D dosimetry are mostly based on various forms of chemical dosimetry such as Fricke dosimetry and the radiation-induced polymerization in solutions of monomers. The 3-D spatial information in these methods is preserved by embedding the radiosensitive chemicals in gel matrices which provide the necessary spatial stability of the dosimeter. The chemical changes in each of these dosimeters are measured by the NMR relaxation characteristics of it (longitudinal or transverse MR relaxation rate R1, R2) which are proportional to its absorbed dose. Advances in the chemical composition of the gels alleviated many irradiation, calibration and measurement uncertainties. Furthermore, advances in MRI technology lead to a more robust and reliable measurement method for 3-D polymer gel dosimetry. It is the scope of this work to present a roadmap, of the progress made thus far in MR imaged polymer gel dosimetry and offer a discussion for the reasons that such a large part of this progress had been disclosed yet unpatented.

Hydroxyapatite (HA) and tricalcium phosphate are two members of the calcium phosphate compounds which have been used clinically for many years. Their good biocompatibility is attributed by its similar chemical composition to that of bone material. Porous calcium phosphate ceramics have found enormous use in biomedical applications including bone tissue regeneration, cell proliferation, and drug delivery. In bone tissue engineering it has been applied as filling material for bone defects and augmentation, artificial bone graft material, and prosthesis revision surgery. Their high surface area leads to excellent osteoconductivity and resorbability providing fast bone ingrowth. Many efforts on the development of porous calcium phosphates can be observed from a considerable numbers of patents which have been filled recently on various methods for preparing porous calcium phosphate for applications of bone implant, chromatography and so on. Porous calcium phosphate can be produced by a variety of methods including conversion of natural bones, ceramic foaming technique, polymeric sponge method, gel casting of foams, solvent casting/ salt leaching method, selective laser sintering, precision extrusion deposition, starch consolidation, microwave processing, slip casting, and electrophoretic deposition technique. Some of these methods have been combined to fabricate porous calcium phosphate with improved properties. These combination methods have yielded some promising results. This paper discusses briefly the fundamental aspects of porous calcium phosphate for biomedical applications as well as the various techniques used to prepare porous calcium phosphate.

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