Biomaterial for Cervical Intervertebral Disc Prosthesis

Recent long-term follow-up studies have shown that the cervical disc arthroplasty treatment have potentials in developing surrounding heterotopic ossification (HO). While its cause requires further investigation, this thesis has hypothesized that it may be the result of the continual remodeling of the injured vertebrae caused by the prostheses with smaller footprints introducing abnormal stresses. The research objective of this thesis is to develop a new prosthesis material that can be molded into any form conforming to the size and shape of the end-plates of the affected patient vertebrae. For prototype development, a composite material consisting of 10wt% polyvinyl alcohol cryogel (PVAc) with embedded long circumferentially oriented bamboo fibers was proposed. An analytical model developed predicts that the compressive strength of such prosthesis is a monotonous increasing function of the fiber volumetric content. Specimens containing volumetric bamboo fiber contents of 0v% (control), 0.6v% and 3v% with 1xPBS were prepared for assessment. The cranial compressive and torsional viscoelastic behavior of specimens were studied with emphasis on its large-scale (till yield) characteristics measured under different strain rates. The mechanical properties measured are compared to that of kangaroo C5-C6 IVDs as our animal model. Mechanical properties such as torsional stress, strain, modulus and impact resistance for viscoelastic materials are not well defined in literatures. This thesis has proposed new definitions for these properties and their derivation methods. It was found that the cryogel process had resulted in a 37v% shrinkage of the composite material which may have caused the bamboo fibers to wrinkle up. A pre-strained of 35% to 45% of the specimens was required to unwrinkled the mid portion of the 3v% composite to match the strength prediction of the analytical model and that of the animal IVD. However, the fiber has not increase much of the torsional strength. With a higher fiber content (e.g., ~5v%), this material may provide the compressive strength comparable to that of our animal model. A prosthesis fabricated with this composite material will be functionally comparable to a class of FDA-approved IVD prostheses with the advantages that it can be molded quickly into patient specific size and shape with no spinal axil rotational alignment required

Sequential changes in hematologic and biochemical parameters in African tick bite fever

ObjectivesTo evaluate the sequential changes and to estimate the frequencies of abnormalities in some commonly measured biological variables in patients with African tick bite fever (ATBF), an emerging spotted fever group (SFG) rickettsiosis in international travelers to rural sub-Saharan Africa.MethodsA study was done of hemoglobin, total leukocyte count, absolute lymphocyte count, blood platelet count and serum levels of C-reactive protein (S-CRP), alanine aminotransferase (S-ALAT), aspartate aminotransferase, lactic dehydrogenase, γ-glutamyl transferase, alkaline phosphatase, bilirubin, sodium and creatinine during the first two weeks of illness and prior to the institution of antirickettsial therapy in 108 patients with travel-associated ATBF.ResultsThere were significant falls in mean total leukocyte count, mean absolute lymphocyte count, and mean platelet count, and significant increases in mean S-CRP and S-ALAT. During the first ten days of illness, elevated S-CRP, lymphopenia and elevated S-ALAT were detected in 91.7%, 73.3% and 40.7% of patients, respectively. Most abnormalities were mild. For 55 patients who underwent both S-CRP and absolute lymphocyte count determination, at least one parameter was abnormal in 52 (94.5%) patients.ConclusionsThe sequential changes in many biological parameters during the acute phase of ATBF mimic those reported in other SFG rickettsioses. Mild abnormalities are frequent, with increased S-CRP and lymphopenia being the two most consistent findings

Figure 1: Characteristics of low temperature

Introduction Though the use of MEG is steadily increasing, there are two ineligible problems to prevent widespread use of MEG; that are the extravagant waste of the expensive liquid helium into the air and the need to transfer liquid helium into a dewar frequently. However there have been few reports that had dealt with this problem. One research was aimed to develop direct cooling system that requires no helium. However, the produced noise from the cooling system seems to prevent normal experiments in the system [1]. So the second feasible way is to collect the evaporated gas and cool it down with a small cryocooler. There are several commercially available such systems for the study of low temperature materials (TRG-350D, Taiyo Toyo Sanso Co., Ltd.; HRT-K212, Sumitomo Heavy Industries, Ltd.). However those systems have a common problem that they require huge electric energy to make liquid helium and they produce big magnetic noise. Hence, we are developing other type of heliu