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Biomedical subjects

W L Lo

Publications and source records attributed to W L Lo.

16 recordsLinked to original sources
PubMed2003

On-line lower-order modeling via neural networks.

This paper presents a novel method to determine the parameters of a first-order plus dead-time model using neural networks. The outputs of the neural networks are the gain, dominant time constant, and apparent time delay. By combining this algorithm with a conventional PI or PID controller, we also present an adaptive controller which requires very little a priori knowledge about the plant under control. The simplicity of the scheme for real-time control provides a new approach for implementing neural network applications for a variety of on-line industrial control problems. Simulation and experimental results demonstrate the feasibility and adaptive property of the proposed scheme.

Algorithms↗
PubMed2003

Self-tuning control of systems with unknown time delay via extended polynomial identification.

Much of the work reported on self-tuning control addresses the class of systems with known time delay. In this paper, the continuous time self-tuning control algorithm is extended to systems with unknown or varying time delay. The original polynomial identification is further modified in this paper to estimate both poles, zeros, and unknown time delay. An explicit self-tuner is then designed based on the estimated parameters. Experimental studies are used to evaluate the performance of this algorithm.

Journal Article↗
PubMed2003

Role of cell surface components on Cu2+ adsorption by Pseudomonas putida 5-x isolated from electroplating effluent.

A gram-negative bacterium Pseudomonas putida 5-x with high Cu2+ accumulating capability was isolated from electroplating effluent in Kwun Tong, Hong Kong. The pretreated cells without superficial layer-capsule, isolated cell envelopes and the separated peptidoglycan layer materials were obtained from fresh P. putida 5-x cells, their Cu2+ adsorption capacities and properties were compared with that of the fresh cells. Pretreatment by 0.1 mol L(-1) HCl enhanced Cu2+ adsorption capacity due to the degradation of cell superficial layer-capsule of P. putida 5-x cells. Isolated cell envelopes possessed five times more Cu2+ adsorption capacity than that of fresh intact cell. The Cu2+ adsorption of separated peptidoglycan layer materials indicated that the peptidoglycan layer only played 10-15% part of the Cu2+ adsorption capacity, and implied other cell surface components such as outer membrane or inner membrane might play an important role in such high Cu2+ binding of the cell envelopes. The adsorption process of fresh cells, pretreated cells and cell envelopes of P. putida 5-x could be described with Freundlich isotherm, while the adsorption of Cu2+ by separated peptidoglycan layer materials was better described with Langmuir isotherm.

Adsorption↗
PubMed2003

Aspergillosis of the temporomandibular joint following irradiation of the parotid region: a case report.

We report a case of aspergillosis in the right temporomandibular joint (TMJ) with a history of parotid carcinoma and post-irradiation otitis. Previous treatment attempts with surgery and antibiotics were unsuccessful. Radical debridement of the glenoid fossae, supplemented with amphotericin B and adjunct hyperbaric oxygen (HBO) therapy, was provided to resolve the symptoms. This case report highlights the need to be aware of the possibility of invasive mycosis in immunocompromised patients.

Aged↗
PubMed2002

Different enzyme activities of sialyltransferases in gynecological cancer cell lines.

PURPOSE: Due to rarity of a relationship between sialyltransferase enzyme activities and gynecological cancers, we arranged the study to evaluate sialyltransferase enzyme activity in the various kinds of gynecological cancer cell lines. METHODS: Ten cell lines from various kinds of gynecological cancers and two cell lines from normal tissue were enrolled in this study. The activities of each subtype of sialyltransferases were detected using Gal beta1,3GalNAc-acetyl-lactosamine)-Obz1 (acceptor for ST2,3Gal I), Gal beta1,3GlcNAc beta1,3Gal beta1,4GlcNAc (acceptor for ST2,3Gal III), Gal beta1,4GlcNAc (acceptor for ST2,3Gal IV), asialo-bovine submaxillary mucin (acceptor for ST2,6GalNAc I), asialo-fetuin (acceptor for STalpha2,6GalNAc II), and fetuin (acceptor for ST2,6GalNAc III), respectively. The amounts of sialic acids were measured using fluorescein-conjugated Sambucus nigra agglutinin (SNA) specific for alpha2,6-sialic acids and fluorescein-conjugated Maackia Amurensis agglutinin (MAA) specific for alpha2,3-sialic acids. RESULTS: The activities of two sialyltransferase subtypes, ST3Gal I & ST6GalNAc II, were significantly higher in nearly all cell lines. More specifically, cervical cancer cell line-ME 180, ovarian cancer cell line-ES-2, and choriocarcinoma cell line-BeWo showed high levels of ST3Gal I enzyme activity; all gynecological cancer cell lines except endometrial cancer cell line-RL95-2 had high levels of ST6GalNAc II enzyme activity when compared with a normal control cell line--fibroblast cell line (CCD-966Sk). Cell lines tested in this study have diverse levels of surface alpha2,6-sialic acid sugar chains (enhanced SNA binding) when compared with alpha2,3-sialic acid sugar chains (enhanced MAA binding) but we found that some cell lines such as Ca Ski (cervical cancer cell line), CC7T (cervical cancer cell line), PA-I (ovarian cancer cell line), and BeWo showed significantly altered cell surface alpha2,6-sialic acid sugar chains. CONCLUSION: Increasing enzyme activity of ST3Gal I and ST6GalNAc II might be important in various kinds of gynecological cancers. More specifically, enhanced activity of sialyltransferases involving alpha2,6-sialic acid sugar chains might be more important in cancer development. Future studies will investigate whether the enzyme activity of these sialyltransferases can be helpful for clinical practice.

Female↗
PubMed2001

Universal antenatal human immunodeficiency virus testing in Hong Kong: consensus statement.

Following the recommendations of the Advisory Council on AIDS, Hong Kong, the Hospital Authority announced plans to introduce universal antenatal screening for human immunodeficiency virus infection and hence, a consensus conference was held to discuss strategies for implementing such screening in Hong Kong. This paper reports the discussions of the consensus conference. The consensus meeting group consisted of 15 clinicians and scientists from Hong Kong, Macau, and Thailand. Seven commonly asked questions concerning mother-to-child transmission of human immunodeficiency virus were selected for discussion by the participating panellists. Information on the laboratory diagnosis of human immunodeficiency virus infection and the efficacy of preventive measures in reducing mother-to-child transmission of human immunodeficiency virus were reviewed. Data from local studies was also presented and discussed. The timing, potential problems, and cost issues involved in testing all pregnant women in Hong Kong for human immunodeficiency virus were then considered.

Adult↗
PubMed1998

The prevention of communicable diseases in Hong Kong.

Some of the recent communicable disease problems in Hong Kong are summarised to illustrate the strengths and weaknesses of how Hong Kong currently controls and prevents communicable diseases. Suggestions on how Hong Kong could improve the control and prevention of communicable diseases are made.

Journal Article↗
PubMed1995

[Neuropsychological assessment in a patient with left hemineglect syndrome--a case report].

We performed a sequential neuropsychological tests before and after neurosurgical intervention on a 69-year-old patient with left hemineglect syndrome caused by metastatic right temporal papillary carcinoma. The tests performed before operation and computer tomography revealed marked impairment in visuospatial reasoning, spatial orientation, visual perception, visuoconstructional praxis, effort emory, as well as block design in Wechsler Adult Intellectual Scale-Revised, all of which suggested right temporo-parietal lesion. Left spatial neglect was obviously demonstrated by the Line Cancellation Test, Watch Test, and clinical observation. After surgical debulking of the tumor, his performances on most of the tests were improved. Our study demonstrated that the conventional neuropsychological test is not only useful for localizing the cerebral lesion but also valid for the assessment of functional recovery after treatment, a role that can never be replaced by any other modern technique.

Aged↗
PubMed1994

Cognitive dysfunction in early onset parkinsonism.

Cognitive functions of 24 patients with early onset parkinsonism (age of onset before 40 years) and 24 controls were investigated by a battery of neuropsychological tests. Patients were shown to be impaired in performance IQ (PIQ), conceptual ability and regulation behavior, memory, visuospatial perception, and manual dexterity. Patients were also shown to have a higher Zung Depression score. However, analysis of the testing scores appeared to indicate that only a small portion of poor performance on neuropsychological tests are depression related. The results demonstrated that patients with early onset parkinsonism, in whom the factor of aging is not as important, still show cognitive dysfunction and suggested that Parkinson's disease itself can cause cognitive impairment.

Adult↗
PubMed1993

Localized pachydermodactyly in tuberous sclerosis.

Pachydermodactyly refers to a rare form of digital fibromatosis involving the proximal portions of the fingers. There are only nine cases reported in the literature, all idiopathic and occurring in young men. We report a 5-year-old Chinese boy with tuberous sclerosis who presented with localized pachydermodactyly since birth. This congenital form of pachydermodactyly may represent an additional cutaneous sign of tuberous sclerosis.

Child, Preschool↗
PubMed1992

Tripe palms: a significant cutaneous sign of internal malignancy.

Tripe palms is a paraneoplastic keratotic skin sign of great predictive value. It is characterized clinically by a curious rugose thickening of the palms with an accentuation of the normal dermatoglyphic ridges and sulci. Histological examination reveals an undulant epidermis with hyperkeratosis, acanthosis and papillomatosis. More than 80 cases have been reported in the literature; 90% of them were associated with an internal malignancy, mostly a carcinoma of the lung or stomach. We herein report a 66-year-old Chinese man with adenocarcinoma of the lung who presented typical tripe palms. Recognition of this distinctive pattern should prompt a meticulous search for an underlying malignancy, particularly lung or gastric carcinoma.

Adenocarcinoma↗
PubMed1990

Solitary sclerotic fibroma.

A 63-year-old Chinese man with a solitary sclerotic fibroma on the abdomen is described. Skin biopsy showed a well-demarcated dermal nodule composed of hypocellular, eosinophilic collagen bundles separated by prominent clefts. Retrospective electron microscopic study revealed wide collagen bundles containing tightly packed collagen fibrils, only 50 nm in diameter. There were no signs of Cowden's disease. To our knowledge, this is the first report of electron microscopic study of sclerotic fibroma. A brief review of the literature is included.

Collagen↗