Phase transformation behaviour of porous NiTi alloys fabricated by capsule-free hot isostatic pressing

Differential scanning calorimetry (DSC) was used to characterize the phase transformation behaviour of porous Ni50Ti50 alloys fabricated by capsule-free hot isostatic pressing (CF-HIP) with different cold compaction pressures. Experimental results reveal that a multi-stage martensitic transformation (MST) exists in the sintered porous NiTi alloys on cooling while the reverse transformation upon heating is either a single or two-stage phase transformation. The DSC thermal analysis indicates that the cold compaction pressure has great effect on the subsequent transformation temperatures. Generally, the phase transformation temperatures of porous NiTi alloys with lower cold compaction pressure are higher than those compacted with higher pressure. With increase in the annealing time, the transformation temperatures increase quickly when the cold compaction pressure was 150MPa. On the other hand, the transformation temperatures change only slightly when the cold compaction pressure was varied from 300MPa to 400MPa. These phenomena can be attributed to the combined effect of larger plastic deformation with higher dislocations density produced by cold compaction and the precipitation of the second phase in the porous NiTi alloys.published_or_final_versio

Phenotypic and functional characterization of corneal endothelial cells during in vitro expansion.

The advent of cell culture-based methods for the establishment and expansion of human corneal endothelial cells (CEnC) has provided a source of transplantable corneal endothelium, with a significant potential to challenge the one donor-one recipient paradigm. However, concerns over cell identity remain, and a comprehensive characterization of the cultured CEnC across serial passages has not been performed. To this end, we compared two established CEnC culture methods by assessing the transcriptomic changes that occur during in vitro expansion. In confluent monolayers, low mitogenic culture conditions preserved corneal endothelial cell state identity better than culture in high mitogenic conditions. Expansion by continuous passaging induced replicative cell senescence. Transcriptomic analysis of the senescent phenotype identified a cell senescence signature distinct for CEnC. We identified activation of both classic and new cell signaling pathways that may be targeted to prevent senescence, a significant barrier to realizing the potential clinical utility of in vitro expansion

Cerebral involvement in neuromyelitis optica spectrum disorders among Hong Kong Chinese

published_or_final_versionThe 16th Medical Resarch Conference (MRC), The University of Hong Kong, Hong Kong, China, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 55, abstract no. 8

An update on irreversible electroporation of liver tumours

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Biomimetic deposition of apatite on surface chemically modified porous NiTi shapememory alloy

Porous NiTi shape memory alloy (SMA) with 48% porosity and an average pore size of 50800 μm was synthesized by capsule-free hot isostatic pressing (CF-HIP). To enhance the surface bioactivity, the porous NiTi SMA was subjected to H"2O"2 and subsequent NaOH treatment. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses revealed that a porous sodium titanate (Na"2TiO"3) film had formed on the surface of the porous NiTi SMA. An apatite layer was deposited on this film after immersion in simulated body fluid at 37°C, while no apatite could be found on the surface of the untreated porous NiTi SMA. The formation of the apatite layer infers that the bioactivity of the porous NiTi SMA may be enhanced by surface chemical treatment, which is favorable for its application as bone implants. © 2008 World Scientific Publishing Company.postprin

Suppression of nickel out-diffusion from porous nickel-titanium shape memory alloy by plasma immersion ion implantation

Summary form only given. Porous nickel titanium is a promising material for medical application not only because of its super elasticity and shape memory effect but also the porous structure which may enhance bone growth due to the increased surface area. It is thus especially suitable for bone tissue in-growth and fixation of biomedical implants. However, like its dense counterpart, Ni leaching from the materials causes health concern. Thus, in order to suppress Ni diffusion from the materials to body fluids and tissues in humans, a diffusion barrier or similar structure must be introduced. In this work, we produced this diffusion barrier layer by oxygen or nitrogen plasma immersion ion implantation (PIII). In vitro tests were conducted by immersing the plasma-treated NiTi into simulated body fluid (SBF) at 37plusmn0.5degC for 5 weeks and the resulting SBF was analyzed for Ni and Ti using inductively-coupled plasma mass spectrometry (ICMPS). Our results show that Ni leaching is significantly mitigated by both nitrogen and oxygen PIII.published_or_final_versio

Prenatal Tobacco Exposure Shortens Telomere Length in Children

Introduction: Preliminary evidence suggests a possible association between prenatal tobacco exposure and telomere length in children. This study was conducted to investigate whether maternal smoking during pregnancy was associated with telomere shortening in their children and whether prenatal and childhood exposure to environmental tobacco had any impact on this association. Methods: This is a population-representative study on the association between prenatal tobacco exposure and telomere length in children. Ninety-eight Hong Kong Chinese children aged under 15 years with prenatal tobacco exposure and 98 age- and gender-matched controls were recruited from a population health study with stratified random sampling. Results: Telomere length in children with prenatal tobacco exposure was significantly shorter than in those with no exposure (mean T/S ratio = 24.9 [SD = 8.58] in exposed vs. 28.97 [14.15] in control groups; P = 0.02). A negative dose-response relationship was observed between the T/S ratio and tobacco exposure duration: the longer the duration of maternal smoking in pregnancy, the shorter the child's telomere length. The association between the child's telomere length and prenatal tobacco exposure remained significant after considering the influence of family socioeconomic status and exposure to environmental tobacco smoke during pregnancy and childhood. Conclusions: Prenatal tobacco exposure was associated with telomere shortening in children. As this may impose significant health impacts through fetal genetic programming, more efforts should be made to reduce fetal tobacco exposure by educating pregnant women to not smoke and motivating smokers to quit in early pregnancy. Implications: As reflected by telomere shortening, prenatal tobacco exposure in children can cause premature aging and increased health risks, which we suggest is entirely preventable. Not smoking during pregnancy or quitting smoking is critical to improving the health outcome of our future generations as prenatal tobacco exposure may affect children's biological programming. © The Author 2016. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved.postprin

Nickel ion level in scoliotic patients implanted with nitrogen plasma surface modified nickel-titanium superelastic spinal implant

published_or_final_versionThe 3rd International NanoElectronics Conference (INEC), Hong Kong, 3-8 January 2010. In Proceedings of the 3rd INEC, 2010, p. 136

The clinical impact of chromosomal microarray on paediatric care in Hong Kong

Objective To evaluate the clinical impact of chromosomal microarray (CMA) on the management of paediatric patients in Hong Kong. Methods We performed NimbleGen 135k oligonucleotide array on 327 children with intellectual disability (ID)/developmental delay (DD), autism spectrum disorders (ASD), and/or multiple congenital anomalies (MCAs) in a university-affiliated paediatric unit from January 2011 to May 2013. The medical records of patients were reviewed in September 2013, focusing on the pathogenic/likely pathogenic CMA findings and their “clinical actionability” based on established criteria. Results Thirty-seven patients were reported to have pathogenic/likely pathogenic results, while 40 had findings of unknown significance. This gives a detection rate of 11% for clinically significant (pathogenic/likely pathogenic) findings. The significant findings have prompted clinical actions in 28 out of 37 patients (75.7%), while the findings with unknown significance have led to further management recommendation in only 1 patient (p<0.001). Nineteen out of the 28 management recommendations are “evidence-based” on either practice guidelines endorsed by a professional society (n = 9, Level 1) or peer-reviewed publications making medical management recommendation (n = 10, Level 2). CMA results impact medical management by precipitating referral to a specialist (n = 24); diagnostic testing (n = 25), surveillance of complications (n = 19), interventional procedure (n = 7), medication (n = 15) or lifestyle modification (n = 12). Conclusion The application of CMA in children with ID/DD, ASD, and/or MCAs in Hong Kong results in a diagnostic yield of ∼11% for pathogenic/likely pathogenic results. Importantly the yield for clinically actionable results is 8.6%. We advocate using diagnostic yield of clinically actionable results to evaluate CMA as it provides information of both clinical validity and clinical utility. Furthermore, it incorporates evidence-based medicine into the practice of genomic medicine. The same framework can be applied to other genomic testing strategies enabled by next-generation sequencing.published_or_final_versio

Dolor posoperatorio en craneotomía

In the postoperative period, 47% to 75% of the patients report some degree of pain. This study aimed to evaluate pain in the pre and postoperative period of patients submitted to craniotomy. This prospective research was carried out at the neurosurgery unit of a large Brazilian hospital. For a quantitative evaluation of pain, the verbal numeric 0 - 10 rating scale was used. Forty patients with a mean age of 36 years were evaluated. In the preoperative period, 34 (85%) patients indicated headache as the main cause of pain. In the postoperative period, 37 (93%) patients complained of pain while three (7%) reported absence of pain. Pain peaks were observed on the 2nd postoperative day, when 12 (32%) of the patients reported severe pain and 10 (27%) moderate pain. Absence of severe pain occurred after the 8th postoperative day. It was concluded that protocols of analgesia in craniotomy are needed, such as training nurses to better evaluate and handle pain.En el periodo postoperatorio, entre el 47% y el 75% de los pacientes relatan algún grado de dolor. Los objetivos de este trabajo fueron evaluar el dolor en el pre y postoperatorio de pacientes sometidos a craneotomía. Este estudio prospectivo fue realizado en la unidad de neurocirugía del Hospital São Paulo, Brasil. Para una evaluación cuantitativa del dolor se utilizó la escala numérica verbal graduada de 0 a 10. Fueron evaluados 40 pacientes con edad mediana de 36 años. En el preoperatorio 34 (85%) pacientes, reportaran cefalea como la principal causa del dolor. En el postoperatorio, 37 (93%) pacientes se quejaron de dolor, mientras 3 (7%) pacientes indicaron ausencia de dolor. El pico de dolor fue observado en el segundo día postoperatorio, cuando 12 (32%) pacientes reportaron dolor grave y 10 (27%) moderado. La ausencia de dolor grave ocurrió después del 8º día postoperatorio. Se concluyó que son necesarios protocolos de analgesia en craneotomía, tales como el entrenamiento de enfermeros para mejor evaluar y manejar el dolor.No pós-operatório, 47 a 75% dos pacientes relatam algum grau de dor. O objetivo deste trabalho foi avaliar a dor no pré e pós-operatório de pacientes submetidos a craniotomia. Estudo prospectivo, realizado na unidade de neurocirurgia do Hospital São Paulo. Para avaliação quantitativa de dor, foi utilizada a escala numérica verbal, graduada de 0 a 10. Foram avaliados 40 pacientes, com idade mediana de 36 anos. No pré-operatório, 34 (85%) pacientes relataram cefaléia como a principal causa de dor. No pós-operatório, 37 (93%) pacientes queixaram-se de dor e 3 (7%) pacientes referiram ausência de dor. O pico da dor foi observado no 2º pós-operatório, quando 16 (40%) dos pacientes referiram dor intensa e 11 (28%) queixaram-se de dor moderada. Ausência de dor intensa ocorreu após 6º pós-operatório. Concluí-se que há necessidade de protocolos de analgesia em craniotomia, como treinamento para os enfermeiros para melhor avaliação e manejo da dor.Hospital Israelita Albert EinsteinUniversidade Federal de São Paulo (UNIFESP)UNIFESPSciEL