A robotic system for rapid prototyping

Reducing prototyping time is a good way to make the product development cycle shorter. This can be achieved in two ways: one is to develop new prototyping technologies like stereolithography apparatus (SLA), selective laser sintering (SLS) etc.; the other is to improve the principal existing technique which is CNC based method. In this paper, a robotic system for rapid prototyping which is an enhancement of the CNC based method is presented. A robot arm holding a milling tool is used to machine the prototype of a solid model drawn in commercial CAD systems. The rough cut and finish cut NC tool path for the robot arm are generated automatically from the solid model of an object. Objects may have different kinds of surfaces e.g. planar surface, general quadratic surface, B-spline surface and compound surface. The proposed method is implemented on the AutoCAD platform. A number of produced prototypes have shown satisfactory results.published_or_final_versio

MR findings in Spinal Hemangioblastoma: correlation with symptoms and surgical findings - the local experience

Meeting Theme: Degenerative Lumbar SpineOral-Poster Presentation 2BACKGROUND AND PURPOSE: Similar study has been performed by Miyasaka et al. in 2001, detailing MR features of spinal haemangioblastoma and its clinical relevance. However, to our knowledge, there was no similar study has been performed in Hong Kong. The purpose of this study was to evaluate the MR features’ correlation with clinical and surgical findings in local setting. METHODS: MR whole spine and the corresponding reports of 6 patients were reviewed via the Electronic Patient Record system (ePR) of Hospital Authority. The symptoms and surgical findings were also traced. They were reviewed retrospectively …published_or_final_versio

Intraoperative direct embolization with N-butyl cyanoacrylate (NBCA) for vascular tumours of the spinal cord: a technical report

Oral-Poster Presentation 1Meeting Theme: Degenerative Lumbar SpineINTRODUCTION: Intramedullary vascular tumors such as hemangioma or hemangioblastoma in the cervical cord are challenging lesions to remove surgically. The vascularity of the lesion can cause significant bleeding and difficulties during tumor debulking and dissection, and increase the risk of spinal cord damage. Pre-operative endovascular embolization is well described for intra-cranial lesions, but seldom used in intraspinal intramedullary tumors due to the technical difficulties and risk of spinal cord ischemia. We describe our experience of intra-operative direct embolization of difficult cervical cord vascular tumors with N-butyl cyanoacrylate (NBCA) glue in achieving prompt hemostasis and facilitating tumor removal …published_or_final_versio

Human cardiac Kv4.3 channels are regulated by protein tyrosine kinases

Poster presentationpublished_or_final_versionThe 15th Annual Research Conference of the Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16, suppl. 1, p. 64, abstract no. 11

Sequential approaches for resection of clival chordoma

Free Paper 7Conference Theme: Degenerative Lumbar SpineINTRODUCTION: Chordomas are extra-axial tumours that originate from the primitive notochord. They are rare diseases that present mostly between the third and the fifth decades of life with an incidence rate of 0.08 per 100,000 in the United States. Approximately 35% of chordomas arise in the clivus of the skull base (clival chordoma). In spite of their slow-growing and non-malignant histopathological appearance, they are potentially life threatening due to their locally destructive and invasive nature. Clival chordomas are located near the spheno-occipital junction at the base of the skull, behind the sphenoid sinuses. Involvement of the surrounding cranial nerves accounts for their symptomatology. It is notorious for its high tendency of recurrence following treatment, with a reported recurrence rate of 68%. Therefore, gross total resection in combination with adjuvant radiotherapy is the standard mode of treatment …published_or_final_versio

Dorsal root entry zone approach in spinal intramedullary tumours: a revisit and review of the technique

Meeting Theme: Degenerative Lumbar SpineOral-Poster Presentation IINTRODUCTION: Surgical excision is the mainstay treatment for the intramedullary spinal cord tumour. However, when no tumour exposed on the surface of the spinal cord in this kind of tumour, myelotomy is required. Median myelotomy (MM) is the standard approach to be described in the literatures, but we did encounter complications probably related to this approach solely. After such incidents, we adopted the dorsal root entry zone myelotomy (DREZM) approach in the surgery treating these intramedullary tumours …published_or_final_versio

Worsened arterial stiffness in high-risk cardiovascular patients with high habitual carbohydrate intake: a cross-sectional vascular function study

BACKGROUND: Previous studies suggested that high dietary carbohydrate intake is associated with increased cardiovascular risk through raised triglyceride and decreased high-density lipoprotein-cholesterol levels. However, the relation between carbohydrate intake and arterial stiffness has not been established. The purpose of this study was to examine this relation among high-risk cardiovascular patients. METHODS: We studied the relation between dietary macronutrient intake and arterial stiffness in 364 patients with documented cardiovascular diseases or risk equivalent (coronary artery diseases 62%, ischemic stroke 13%, diabetes mellitus 55%) and in 93 age-and-sex matched control subjects. Dietary macronutrient intake was assessed using a validated food-frequency questionnaire (FFQ) for Chinese. Heart-ankle pulse wave velocity (PWV) was measured non-invasively with a Vascular Profiling System (VP2000, Colin Corp. USA). A dietary pattern with >/=60% total energy intake derived from carbohydrates was defined as a high-carbohydrate diet according to the Dietary Reference Intakes (DRI) for Chinese. RESULTS: Subjects who consumed a high-carbohydrate diet had significantly higher mean PWV than those who did not consume a high-carbohydrate diet (P = 0.039). After adjustment for potential confounders, high-carbohydrate diet was associated with significantly increased PWV [B = 73.50 (10.81 to 136.19), P = 0.022]. However, there was no significant association between high-carbohydrate diet and PWV in controls (P = 0.634). CONCLUSIONS: High-carbohydrate diet is associated with increased arterial stiffness in patients with established cardiovascular disease or risk equivalent.published_or_final_versio

Incremental predictive value of vascular assessments combined with the Framingham Risk Score for prediction of coronary events in subjects of low-intermediate risk

Background: In patients with low-intermediate risk, the use of the Framingham Risk Score (FRS) may not allow accurate prediction of the occurrence of coronary events. Objective: To determine whether non-invasive vascular sonographic assessments add value to the FRS for prediction of coronary events. Methods: Brachial artery flow-mediated dilatation (FMD), carotid intima-media thickness (IMT) and the presence of carotid plaque in 70 male subjects (mean (SD) age 62 (9) years) with a low-intermediate FRS who presented with a recent coronary event were evaluated and compared with those in 35 male controls matched for age (mean age 60 (9) years). Results: Patients with a recent coronary event had a significantly higher FRS than controls. They had a significantly lower FMD (3.56 (2.41)% vs 5.18 (2.69)%, p = 0.003) and significantly higher prevalence of carotid plaque (67% vs 40%, p = 0.008), but there was no significant difference in mean maximum IMT between the two groups (1.01 (0.28) vs 0.96 (0.14) mm, p = 0.32). Multivariate analysis revealed that FMD ≤ 4.75% was an independent predictor of an acute coronary event. Of the three vascular markers, FMD ≤ 4.75% and presence of carotid plaque provided the best diagnostic accuracy for a coronary event, with area under the curve (AUC) of 0.70 and 0.64 (p = 0.001 and p = 0.033), respectively, based on receiver operating characteristic curve analysis. Furthermore, incorporating carotid plaque or FMD ≤ 4.75% into the FRS (AUC = 0.72 and AUC = 0.78) provided incremental benefit in risk stratification over FRS alone (AUC = 0.66) (p = 0.008 and p = 0.007, for comparison of difference in two receiver operating characteristic curves). Conclusions: Incorporating a measure of FMD or carotid plaque burden with FRS significantly increases the accuracy of predicting coronary events in subjects of low-intermediate risk and hence should be considered as additional investigations to improve coronary risk assessment.published_or_final_versio

PR interval prolongation in coronary patients or risk equivalent: excess risk of ischemic stroke and vascular pathophysiological insights

published_or_final_versio

Predictive value of high-sensitivity troponin-I for future adverse cardiovascular outcome in stable patients with type 2 diabetes mellitus

INTRODUCTION: High-sensitivity cardiac troponin I(hs-TnI) and T levels(hs-TnT) are sensitive biomarkers of cardiomyocyte turnover or necrosis. Prior studies of the predictive role of hs-TnT in type 2 diabetes mellitus(T2DM) patients have yielded conflicting results. This study aimed to determine whether hs-TnI, which is detectable in a higher proportion of normal subjects than hsTnT, is associated with a major adverse cardiovascular event(MACE) in T2DM patients. METHODS AND RESULTS: We compared hs-TnI level in stored serum samples from 276 consecutive patients (mean age 65 +/- 10 years; 57% male) with T2DM with that of 115 age-and sex-matched controls. All T2DM patients were prospectively followed up for at least 4 years for incidence of MACE including heart failure(HF), myocardial infarction(MI) and cardiovascular mortality. At baseline, 274(99%) patients with T2DM had detectable hs-TnI, and 57(21%) had elevated hs-TnI (male: 8.5 ng/L, female: 7.6 ng/L, above the 99th percentile in healthy controls). A total of 43 MACE occurred: HF(n = 18), MI(n = 11) and cardiovascular mortality(n = 14). Kaplan-Meier analysis showed that an elevated hs-TnI was associated with MACE, HF, MI and cardiovascular mortality. Although multivariate analysis revealed that an elevated hs-TnI independently predicted MACE, it had limited sensitivity(62.7%) and positive predictive value(38.5%). Contrary to this, a normal hs-TnI level had an excellent negative predictive value(92.2%) for future MACE in patients with T2DM. CONCLUSION: The present study demonstrates that elevated hs-TnI in patients with T2DM is associated with increased MACE, HF, MI and cardiovascular mortality. Importantly, a normal hs-TnI level has an excellent negative predictive value for future adverse cardiovascular events during long-term follow-up.published_or_final_versio