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Biomedical subjects

F Hui

Publications and source records attributed to F Hui.

At least 19 recordsLinked to original sources
PubMed2006

Retrieving leaf area index for coniferous forest in Xingguo County, China with Landsat ETM+ images.

Spatial distributions of the leaf area index (LAI) needed for carbon cycle modeling in Xingguo County, China were estimated based on correlations between the field-measurements and vegetation indices (VIs). After making geometric and atmospheric corrections to two Landsat ETM+ images, one in January 2000 and the other in May 2003, three VIs (SR, NDVI, and RSR) were derived, and their separate correlations with ground LAI measurements were established. The correlation with RSR was the highest among the three VIs. The retrieved LAI values for January 2000 were lower than those for May 2003 because of a small seasonal variation in the coniferous forests (predominantly masson pine) and the decrease in the understorey vegetation during winter.

Atmosphere↗
PubMed2006

Early experiences with diffusion tensor imaging and magnetic resonance tractography in stroke patients.

INTRODUCTION: Recent advances in magnetic resonance (MR) diffusion tensor imaging technique enable evaluation of the anisotropy of white matter tracts in-vivo, as well as the integrity of fibre tracts and their orientation. We describe our initial experiences with diffusion tensor imaging and MR tractography techniques to evaluate the structural degeneration of white matter tracts following stroke. METHODS: Diffusion tensor imaging data were acquired in 11 cases with stroke on a 3T MR imaging scanner, with three-dimensional diffusion tensor imaging-based colour maps and MR tractography performed offline. We evaluated the spatial relationships of the eloquent white matter tracts to the infarcts and areas of haemorrhage, and classified therewith the tracts as either disrupted or displaced. We compared these with the clinical severity of the neurological deficits and prognosis. RESULTS: A good correlation was found between tractography findings and patient's clinical recovery. All the patients with disruption of white matter tracts had residual deficits on clinical follow-up, whereas the patients with displaced tracts had near complete neurological recovery. CONCLUSION: Diffusion tensor imaging and MR tractography provide a novel and useful method to directly visualise changes in the white matter tracts in stroke. This can potentially allow clinical-imaging correlation with prognostic potential.

Aged↗
PubMed2006

Retropharyngeal haemorrhage from a vertebral artery branch treated with distal flow arrest and particle embolisation.

Retropharyngeal haematoma is a rare cause of rapid neck swelling that may result in fatal upper respiratory airway obstruction. Reported causes include trauma, surgery, retropharyngeal inflammation, carotid aneurysm, aberrant artery at the thoracic inlet and bleeding diathesis. We report a 90-year-old man who developed rapid and progressive neck swelling following a minor traumatic episode. Computed tomography showed a large low-density retropharyngeal haematoma extending from the skull base to the mediastinum, with suspected extravasation. The right vertebral artery angiogram confirmed contrast agent extravasation arising from a small branch artery. This was treated with temporary distal flow arrest and particle embolisation.

Aged, 80 and over↗
PubMed2005

Normal variants of the intracranial circulation demonstrated by MR angiography at 3T.

Magnetic resonance angiography (MRA) at 3T offers increased signal to noise ratio with better background suppression, leading to exquisite depiction of the intracranial circulation. We present a pictorial review of the normal variations and anomalies of the intracranial circulation detected on MRA performed on a high field 3T clinical scanner using parallel imaging techniques. The salient imaging features of these anomalies and normal variations are discussed with relevance to clinical practice.

Anterior Cerebral Artery↗
PubMed2004

Intravascular papillary endothelial hyperplasia in an intracranial thrombosed aneurysm: 3T magnetic resonance imaging and angiographical features.

Enhancement of intracranial thrombosed aneurysms is an uncommon finding on magnetic resonance (MR) imaging, and can present diagnostic difficulties and complicate management decisions. We report a 46-year-old man who had an enhancing thrombosed intracranial aneurysm observed on 3T MR imaging. There was angiographical correlation, with follow-up serial MR imaging documenting regression and improvement. Findings are typical for benign intravascular papillary endothelial hyperplasia. Differential diagnoses of giant serpentine intracranial aneurysm and malignant angiosarcoma are discussed.

Angiography, Digital Subtraction↗
PubMed2003

Late clinical and magnetic resonance imaging follow up of Nipah virus infection.

The Nipah virus is a newly identified paramyxovirus responsible for an outbreak of fatal encephalitis in Malaysia and Singapore. This paper reports the follow up clinical and magnetic resonance imaging findings in 22 affected subjects. Of 13 patients with encephalitis, one died, one was lost to follow up, and seven recovered. Among the four remaining patients, one had residual sixth nerve palsy, another suffered from severe clinical depression, and a third patient had evidence of retinal artery occlusion. One patient with delayed onset Horner syndrome had a single lesion in the cervical spinal cord. The brain magnetic resonance findings were stable or improved in nine patients over 18 months of follow up. Among a second group of nine asymptomatic seropositive abattoir workers, magnetic resonance examination in seven subjects revealed discrete small lesions in the brain; similar to those detected in encephalitis patients. These findings suggest that in addition to encephalitis, the newly discovered Nipah virus affects the spinal cord and the retina. Late clinical and radiological findings can occur in Nipah virus infections as with other paramyxoviruses.

Abducens Nerve Diseases↗
PubMed2003

Diffusion-weighted MR imaging in intracranial infections.

INTRODUCTION: Diffusion-weighted magnetic resonance (MR) imaging (DWMRI) is valuable in the assessment of acute cerebral infarction and may be useful for other diseases of the central nervous system (CNS). In this study, we present the DWMRI appearance of intracranial infection. MATERIALS AND METHODS: Thirty patients with clinical diagnosis of CNS infection were reviewed. All patients underwent conventional contrast-enhanced MR examination and DWMRI using single-shot echo-planar imaging at b = 1000 s/mm2. RESULTS: Cerebral abscess, tuberculoma, subdural empyema and epidural abscess were hyperintense on DWMRI. Neurocysticercosis showed hypointense lesions on DWMRI. Four of 5 patients with encephalitis showed DWMRI hyperintensity; the appearance of toxoplasmosis lesions was variable. Patients suffering from meningitis without parenchymal involvement did not exhibit any abnormality of diffusion. One patient with tuberculous meningitis developed abnormality on DWMRI from acute cerebral infarction. CONCLUSION: DWMRI increased lesion conspicuity and may be useful in assessment of cerebral infection. There were striking differences in the DWMRI appearances caused by different organisms and diseases.

Brain Abscess↗
PubMed2003

Clinics in diagnostic imaging (91). Subarachnoid haemorrhage.

Computed tomography (CT) is the initial radiological investigation of patients with an acute neurological event. A 64-year-old woman presenting with generalised weakness and headache for two days was diagnosed on CT to have subarachnoid haemorrhage. Digital subtraction angiography confirmed the cause to be a ruptured posterior communicating artery aneurysm. The patient was treated by neuroradiological intervention using occlusive coils. The CT features of subarachnoid haemorrhage are discussed. Accurate CT interpretation is essential to direct appropriate investigations and management in patients with stroke, particularly as acute cerebral infarction may occasionally mimic subarachnoid haemorrhage. The role of magnetic resonance (MR) imaging in evaluation of cerebral infarct is also discussed.

Female↗
PubMed2003

Rising signal intensity observed in extra-axial brain tumours - a potential pitfall in perfusion MR imaging.

OBJECTIVE: Dynamic perfusion magnetic resonance (MR) techniques may be used to track the susceptibility effects of gadolinium contrast material as it passes through the brain. We describe three intracranial tumours that showed progressively rising signal intensity above the baseline during first-pass contrast-enhanced echo-planar imaging (EPI) MR imaging. METHODS: Multiphase acquisition using single-shot EPI was performed during rapid bolus contrast injection. Ten studies, using either spin-echo or gradient-echo EPI sequences, were carried out in eight patients with intracranial tumours. Time-signal intensity graphs and regional cerebral blood volume (rCBV) were reviewed. RESULTS: In seven studies, the signal intensity within the tumour showed initial signal drop and quick recovery to baseline and increased rCBV. Three studies revealed progressively rising signal intensity. These patients were all imaged using a spin-echo EPI method and subsequent histology revealed meningioma, hemangiopericytoma and pinealblastoma. CONCLUSION: Dynamic perfusion MR methods may be used to study intracranial tumours. However, in short relaxation time spin-echo EPI, the T1- effect of gadolinium becomes noticeable during the first-pass acquisition in extra-axial tumours that lack a well-developed blood-brain barrier. Careful selection of patients and pulse sequence is essential to avoid this potential pitfall.

Adult↗
PubMed2001

High-performance liquid chromatographic and capillary electrophoretic enantioseparation of plant growth regulators and related indole compounds using macrocyclic antibiotics as chiral selectors.

Enantioseparation of plant growth regulators, such as 3-(3-indolyl)-butyric acid, abscisic acid and structurally related molecules including a variety of substituted tryptophan compounds, has been achieved by HPLC and/or CE. The covalently bonded macrocyclic antibiotics, teicoplanin, ristocetin A and vancomycin, were used as chiral stationary phases (CSPs) in HPLC. Most of the racemates were baseline resolved in the reversed-phase mode (EtOH-H2O) using the teicoplanin CSP. The chiral recognition mechanism is discussed in regard to the structure of the analytes. In CE, the three aforementioned macrocyclic antibiotics were used as chiral additives in a phosphate run buffer. The effect of pH and the concentration of the organic modifiers were considered. The results obtained by HPLC and CE were compared.

Anti-Bacterial Agents↗
PubMed2000

Nipah viral encephalitis or Japanese encephalitis? MR findings in a new zoonotic disease.

BACKGROUND AND PURPOSE: An epidemic of suspected Japanese encephalitis occurred in Malaysia in 1998-1999 among pig farmers. In neighboring Singapore, an outbreak occurred among pig slaughterhouse workers. It was subsequently established that the causative agent in the outbreak was not the Japanese encephalitis virus but a previously unknown Hendra-like paramyxovirus named Nipah virus. METHODS: The brain MR images of eight patients with Nipah virus infection were reviewed. All patients tested negative for acute Japanese encephalitis virus. Seven patients had contrast-enhanced studies and six had diffusion-weighted examinations. RESULTS: All patients had multiple small bilateral foci of T2 prolongation within the subcortical and deep white matter. The periventricular region and corpus callosum were also involved. In addition to white matter disease, five patients had cortical lesions, three had brain stem involvement, and a single thalamic lesion was detected in one patient. All lesions were less than 1 cm in maximum diameter. In five patients, diffusion-weighted images showed increased signal. Four patients had leptomeningeal enhancement and four had enhancement of parenchymal lesions. CONCLUSION: The brain MR findings in patients infected with the newly discovered Nipah paramyxovirus are different from those of patients with Japanese encephalitis. In a zoonotic epidemic, this striking difference in the appearance and distribution of lesions is useful in differentiating these diseases. Diffusion-weighted imaging was advantageous in increasing lesion conspicuity.

Abattoirs↗
PubMed1999

Meningoencephalitis caused by a novel paramyxovirus: an advanced MRI case report in an emerging disease.

Eleven abattoir workers in Singapore were infected in March 1999 by an outbreak caused by the Nipah virus. This newly discovered, Hendra-like paramyxovirus causes acute infection of the CNS. We present the magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) findings in a patient suffering from acute meningoencephalitis. Multiple small white matter lesions were detected on diffusion-weighted imaging (DWI) and T2-weighted images. There were no abnormalities detected on MRS. We believe this to be the first reported MRI findings in this novel zoonotic viral disease.

Abattoirs↗
PubMed1999

Integrative approach to the treatment of postherpetic neuralgia: a case series.

OBJECTIVE: To determine if the addition of alternative therapy to conventional medicine enhances the treatment of pain in postherpetic neuralgia (PHN). METHODOLOGY: A review of literature from 1988-1998 was conducted on the MEDLINE database, searching for information on the current treatment of PHN. The literature review found that although many medications have been used to reduce the pain of PHN, no treatments have been completely successful in decreasing pain. Data on pain reduction in PHN following treatment with a multifaceted alternative therapy combined with conventional treatment were compiled from a group of patients in the principal investigator's family medicine practice. RESULTS: The alternative therapy employed in this study, combined with selected medications, showed an average pain reduction of 72.1 percent. There was a 77-percent average pain reduction in patients with herpes zoster (HZ) onset of more than one year and a 68-percent reduction in patients with HZ onset between one month and one year. Almost two-thirds of the 56 PHN patients reported pain reductions of between 75 and 100 percent. CONCLUSION: These preliminary data suggest the combination of alternative therapy and selected conventional medications provides good pain relief for most patients presenting with PHN. Randomized trials with appropriate control groups are needed to validate the effectiveness of this therapy in the treatment of PHN.

Acupuncture Therapy↗
PubMed1998

Cartilage damaging activities of fibronectin fragments derived from cartilage and synovial fluid.

OBJECTIVE: To investigate whether fibronectin fragments (Fn-fs), shown to damage cultured cartilage, can be found in cartilage from patients with osteoarthritis (OA) or rheumatoid arthritis, or can be generated from fibronectin (Fn) within synovial fluids or from Fn in the matrix of cultured cartilage. To also determine whether cartilage or synovial fluid Fn-fs are active and, thus, could contribute to cartilage damage in vivo. METHODS: Fn-fs were immunochemically identified in cartilage extracts from patients with OA or rheumatoid arthritis or in bovine cartilage cultured with IL-1 alpha or in bovine synovial fluids treated with stromelysin-1 (MMP-3). The effect of removal of Fn-fs from OA synovial fluids was tested by passing fluids over an anti-Fn column and adding the resultant fluids to bovine cartilage cultures to measure proteoglycan (PG) degradation. Gelatin-Sepharose purified Fns from bovine plasma, synovial fluid or cartilage were digested with MMP-3 and the Fn-fs tested for degradation of PG in cultured cartilage. RESULTS: Extracts of cartilage from patients with rheumatoid arthritis or with OA contained a range of Fn-fs. Removal of Fn-fs from OA synovial fluids significantly reduced the resultant damage when the fluids were added to cultured cartilage. Addition of IL-1 alpha to cultured cartilage or of MMP-3 to synovial fluids enhanced generation of Fn-fs. Fn-fs, whether derived from bovine plasma or synovial fluid or cartilage Fns, damaged cartilage. CONCLUSIONS: These data demonstrate that although Fn-fs could be generated in vivo within synovial fluids and Fn-fs found in OA synovial fluid may contribute to cartilage damage in vivo, Fn-fs could also be generated within cartilage and amplify cartilage damage. Thus, Fn-fs may be both autocrine and paracrine regulators of cartilage metabolism.

Animals↗
PubMed1998

Carotid artery dissection presenting as a painless Horner's syndrome in a pilot: fit to fly?

We describe a case of a middle-aged Caucasian pilot who presented to us with a painless left Horner's syndrome due to a focal dissection of the infra-petrous portion of the ipsilateral internal carotid artery. He did not suffer symptoms of cerebral ischemia at the time of onset, or during the following 2 yr. The Horner's syndrome persisted unchanged throughout follow-up. Serial magnetic resonance angiograms showed some regression of the focal stenosis at 12 mo, with no further change over the next 10 mo. The literature suggests that the risk of stroke after onset of dissection is usually in the first month, and the risk of recurrence of dissection is about 1% per year after the first year. Our patient was prescribed aspirin 300 mg.d-1, and certified to fly as or with a co-pilot commencing 1 yr after onset of his symptoms.

Aerospace Medicine↗
PubMed1997

Fibronectin-fragment-induced cartilage chondrolysis is associated with release of catabolic cytokines.

Fibronectin fragments have both catabolic and anabolic activities toward articular cartilage explants in vitro. Whereas a 1 nM concentration of an N-terminal 29 kDa fibronectin fragment (Fn-f) increases the proteoglycan (PG) content of cartilage without induction of matrix metalloproteinases (MMPs), 0.1-1 microM Fn-f temporarily suppresses PG synthesis and enhances MMP release. The higher concentrations cause an initially rapid PG depletion during the first week of culture, followed by much slower PG loss and gradually increasing rates of PG synthesis. To test for the involvement of mediators, human articular cartilage was cultured with Fn-f, and conditioned media were assayed for selected cytokines and factors. With 1 nM Fn-f, the release of the anabolic factors, insulin growth factor-I and transforming growth factor beta1, from cultured cartilage was enhanced by 50-100% during the entire 28-day culture period and this was associated with both supernormal rates of PG synthesis and PG content. However, the higher concentrations of Fn-f additionally enhanced release, by at least 10-fold, of the cytokines, tumour necrosis factor alpha, interleukin-1alpha, interleukin-1beta and interleukin-6 while causing depletion of cartilage PG. Release of tumour necrosis factor alpha, interleukin 1beta and interleukin 1alpha peaked at days 2, 3 and 9 during or slightly after the period of maximal PG depletion and decreased to control levels by days 7, 7 and 21 respectively, whereas release of interleukin 6 was enhanced throughout the culture period. Neutralizing antibodies to the catabolic cytokines reduced Fn-f-mediated MMP-3 release and suppression of PG synthesis. The temporal aspects of this interplay between catabolic and anabolic factors are consistent with the kinetics of Fn-f-mediated cartilage damage and attempted repair and may be relevant to cartilage damage and repair in vivo.

Age Factors↗