Browsing Theses and Dissertations by Subject "Biomedical engineering"
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A Novel Design of a Knee Brace for Patients with Spinocerebellar Ataxia: A Comparative StudySpinocerebellar ataxia (SCA) is an inherited degenerative disease of the central nervous system leading to the deterioration of the cerebellum, the voluntary motor control center of the brain. Patients with SCA are unable to maintain balance and normal posture and have an ataxic gait, resulting in increased abnormalities in gait parameters. Some patients may increase muscle co-activation to provide stability during gait by stiffening their joints. A compensation that typically results in reduced joint range of motion and a decrease of gait parameters. The subject of this study is a 47-year-old female with spinocerebellar ataxia type 2 and presents with difficulty standing, abnormal ataxic gait, and poor balance. The purpose of this study was to design and construct a brace to provide stability and aid the patient in walking as well as standing and sitting. Two braces were designed, constructed, and tested to compare the efficacy of each: a tension brace with an adjustable Velcro tension band attachment on the anterior portion of the brace and a spring brace with a torsional spring and 3D printed housing attached to the brace knee joint. Electromyography analysis determined the knee antagonist co-activation index (CAI) increased by 86.3% during stance and by 168.7% during swing with the spring brace, indicating greater stability and motor control. The tension brace had little to no effect on CAI. During standing, the tension brace increased quadriceps activity by 65.4% and the spring brace increased activity by 37.2%, indicating both braces could help to rehabilitate weak muscle function. Joint angle diagrams obtained in the gait analysis determined both braces aid the knee during the terminal stance and pre-swing. With the spring brace, cadence increased by 8.7% (72.4 steps/min) and velocity by 8% (0.53 m/s), while the tension brace increased cadence 4.9% (69.7 steps/min) and velocity remained unchanged. The F-Scan pressure analysis determined the spring brace decreases abnormal peak force during loading which can indicate balance problems at heel strike. The patient preferred using the spring brace to the tension brace. She felt it provided her more stability and speed and elected to keep the brace after testing.
Characterization of Attenuated HSV-2 Mutants as Potential Vaccine Candidates Against Genital HerpesA prophylactic and therapeutic vaccine against herpes simplex virus type 2 (HSV-2) infection is necessary to reduce the global disease burden of HSV-2 diseases. Subunit, single-cycle, and DNA vaccines have been studied in pre-clinical and clinical trials but have not been approved mostly due to lack of sufficient efficacy. Using targeted mutagenesis, a live, attenuated HSV-2 could be a likely candidate for a protective vaccine. In this study, we constructed and characterized two novel HSV-2 mutant strains, TKBAC /∆UL24 and TKBAC /∆UL39, that have loss-of-function in genes that are associated with viral pathogenesis. Bacterial artificial chromosome (BAC) technology and recombineering were used for construction of these strains and their revertants, TKBAC /UL24R and TKBAC /UL39R. ∆UL24 and ∆UL39 have internal deletions and TKBAC (the parent virus) has an insertion within the viral thymidine kinase gene consisting of the 7.5 kb BAC sequence. Sequencing of ∆UL24 and ∆UL39 confirmed the expected deletions with the HSV-2 UL24 and UL39 genes while the flanking regions remained intact. BAC DNAs were digested with select restriction endonucleases and fractionated by agarose gel electrophoresis. All constructs showed a similar digestion pattern compared to the parent strain, TKBAC, suggesting the mutant genomes were stable. Mutagenized BACS were used to create infectious virus stocks after transfection into Vero cells. We demonstrated that TKBAC /∆UL24 and TKBAC /∆UL39 were replication-competent in Vero cells. An HSV-2 UL24 mutant was shown to be a potential attenuated vaccine candidate in previous studies. The double mutant containing disruption of the TK gene would provide for an even safer attenuated vaccine candidate that would be less like to reactivate from latency and cause disease. Replication characteristics including a reduction in plaque size for TKBAC /∆UL39 suggested that this virus was crippled in vitro, while TKBAC /∆UL24 demonstrated similar replication characteristics to the parent strain. In vitro plaque reduction assays and viral yield assays against acyclovir suggest that TKBAC /∆UL39 is more sensitive to acyclovir compared to the parent strain, based on a lower IC50. Based on previous studies with individual TK or UL39 mutants, the double mutant should be even more deficient in the establishment of and reactivation from latency. Based on these results, TKBAC /∆UL24 and TKBAC /∆UL39 should be considered for further preclinical evaluation (in animal models) as viable candidates for a protective, safe prophylactic and therapeutic vaccine.