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Biomedical subjects

K C Wong

Publications and source records attributed to K C Wong.

At least 19 recordsLinked to original sources

Medical informatics--the state of the art in the Hospital Authority.

Since its inception in 1990, the Hospital Authority (HA) has strongly supported the development and implementation of information systems both to improve the delivery of care and to make better information available to managers. This paper summarizes the progress to date and discusses current and future developments. Following the first two phases of the HA information technology strategy the basic infrastructural elements were laid in place. These included the foundation administrative and financial systems and databases; establishment of a wide area network linking all hospitals and clinics together; laboratory, radiology and pharmacy systems with access to results in the ward. A major push into clinical systems began in 1994 with the clinical management system (CMS), which established a clinical workstation for use in both ward and ambulatory settings. The CMS is now running at all major hospitals, and provides single logon access to almost all the electronically collected clinical data in the HA. The next phase of development is focussed on further support for clinical activities in the CMS. Key elements include the longitudinal electronic patient record (ePR), clinical order entry, generic support for clinical reports, broadening the scope to include allied health and the rehabilitative phase, clinical decision support, an improved clinical documentation framework, sharing of clinical information with other health care providers and a comprehensive data repository for analysis and reporting purposes.

China↗

Molecular mimicry: anti-DNA antibodies may arise inadvertently as a response to antibodies generated to microorganisms.

The origin of anti-DNA antibodies remains speculative. We argue that some of these antibodies may arise inadvertently in nature during the course of a normal immune response due to their induction by antibodies which bear structures (mimotopes) that mimic DNA. These antibodies are not necessarily DNA specific but, like the T15 idiotype (id)-positive antibodies which bind to phosphorylcholine, are produced normally to some environmental or microbial antigen. Such a mimotope was found in a T15(+) antibody at the highly specific region encoded principally by the D gene, DFL16.1. This mimotope was also found in human antibodies that are encoded by DXP'1, the human counterpart of DFL16.1 and which is used commonly in anti-DNA antibodies. The mimotope is closely related to the epitope responsible for the T15 id and appears to be cryptic or normally hidden in the native protein. The existence of such a common, conserved sequence raises questions about how easily anti-DNA antibodies can be generated in nature and what purpose these proteins may serve. Molecular mimicry with regard to autoimmunity must thus be viewed as existing not necessarily between the infectious agent and self-antigens, but also between the antibodies induced by the organism and the self-antigens.

Animals↗

The effect of intraischemic mild hypothermia on focal cerebral ischemia/reperfusion injury.

BACKGROUND: The protective role of intraischemic mild hypothermia on brain injury associated with cerebral ischemia/reperfusion was investigated using a localized, no-flow cerebral ischemia/reperfusion model in rats in vivo. METHODS: Male Wistar rats weighing 250-350 g were anesthetized lightly with halothane. All rats were randomly allocated into two series experiments the first of which was for study of infarct volume and the second of which was for study of NO (nitric oxide) content, and then subjected to various time intervals of focal ischemia followed by reperfusion. The intraischemic mild hypothermia was induced by feedback-regulated semiconductor cooling block in a group of these rats. Normothermia groups were considered as the control groups. The infarct volume and the NO content of rat brain were measured in different groups and hours respectively. RESULTS: The infarct volume of mild hypothermia group was significantly different from that of normal control group within the time window of 10 min (P < 0.05), infarcted brain volumes in hypothermic rats were significantly smaller than in normothermic rats, for the time window of 1 h there was no significant difference in the infarct volume between mild hypothermic group and normothermic control group (P > 0.5). Furthermore, increased tissue levels of NO, a potential mediator of cerebral injury in the brain following focal ischemia were depressed by mild hypothermia. CONCLUSIONS: It is suggested that localized mild hypothermia may be a protective against focal cerebral ischemia/reperfusion injury and that the decreased nitric oxide production in the brain may serve as the protective mechanism of hypothermia.

Animals↗

Excitatory amino acid receptor antagonist 2APH may improve local CBF during cerebral ischemia in cats.

BACKGROUND: The present study was designed to investigate in a focal cerebral ischemia model the influence of 2APH, a competitive NMDA receptor antagonist, on the cerebral blood flow of cat cortex, given intravenously before cerebral ischemia. METHODS: Thirty-four male cats weighing 2.5 to 3.5 kg were anesthetized with halothane and then randomly assigned to either control or experimental group. In the experimented group 18 cats were treated with 2APH and in the control group 16 cats were given saline 10 min before middle cerebral artery occlusion (MCAO). Cortical blood flow (CBF), determined by laser Doppler ultrasound flowmetry, was measured 1 h, 2 h, 3 h, 4 h and 5 h after occlusion. Infarct volume was calculated by summing up the areas in each stained brain section after the experiment. RESULTS: There was a significant difference in the infarct volume of cortex between the 2APH group and the saline control group (P < 0.05). Moreover, we did notice an apparent decrease of the infarct volume in basal ganglia area when 2APH was given (P < 0.01). The total infarct volume was significantly smaller in the group treated with 2APH after MCAO as compared with the saline control group (P < 0.01). CONCLUSIONS: The data from the present experiment suggest that NMDA antagonists may not only antagonize the neurotoxic effect of excitatory amino acid on ischemic neuron but also improve the CBF of ischemic brain.

2-Amino-5-phosphonovalerate↗

A human and a mouse anti-idiotypic antibody specific for human T14(+) anti-DNA antibodies reconstructed by phage display.

Little is known about human anti-idiotypic antibodies. Phage display methodology was used to reconstruct these antibodies from lupus patients, which recognize a subset (T14(+)) of anti-DNA antibodies. Antigen-specific B cells were isolated from the blood using a peptide based on a complementarity determining region (V(H)CDR3) of the prototypic T14(+) antibody. cDNA fragments of the V(H) and V(L) genes prepared from the cells were expressed as phage displayed single chain Fv (scFv) fragments using the pCANTAB-5E phagemid vector. From a reactive clone obtained, the Ig genes used were identified to be V(H)3, D5-D3, J(H)4b, V(kappa)I and J(kappa)2. The heavy chain was highly mutated, especially in CDR3, which bears mutations mostly of the replacement type; this region is also unusual in being extremely long due to a D-D fusion. In contrast, a mouse hybridoma antibody, made to the same T14(+) peptide and transformed as a scFv fragment, uses a short V(H)CDR3 comprising five amino acids, three of which are tyrosines. Tyrosines may be important for antigen binding because two of these also exist in the human V(H)CDR3. The light chains of both antibodies may also contribute to the specificity of the protein, because their V(L) segments, including the CDRs, are highly homologous to each other.

Amino Acid Sequence↗

Type II myosin regulatory light chain relieves auto-inhibition of myosin-heavy-chain function.

The F-actin based motor protein myosin II has a key role in cytokinesis. Here we show that the Schizosaccharomyces pombe regulatory light chain (RLC) protein Rlc1p binds to Myo2p in manner that is dependent on the IQ sequence motif (the RLC-binding site), and that Rlc1p is a component of the actomyosin ring. Rlc1p is important for cytokinesis at all growth temperatures and is essential for this process at lower temperatures. Interestingly, all deleterious phenotypes associated with the loss of Rlc1p function are suppressed by deletion of the RLC binding site on Myo2p. We conclude that the sole essential function of RLCs in fission yeast is to relieve the auto-inhibition of myosin II function, which is mediated by the RLC-binding site, on the myosin heavy chain (MHC).

Amino Acid Sequence↗

Pemphigus with pemphigoid-like presentation, associated with squamous cell carcinoma of the tongue.

A 53-year-old woman presented with an inoperable squamous cell carcinoma of the tongue associated with tense large bullae consistent with bullous pemphigoid, preceded by a prodrome of urticarial plaques. The histological findings showed a regenerating subepidermal blister with eosinophils and no acantholysis. Direct immunofluorescence study, however, showed positive staining for IgG and C3 throughout the epidermis consistent with pemphigus. The blistering eruption had no mucosal involvement and responded to low dose corticosteroids. Our patient may represent another presentation of a 'paraneoplastic pemphigus spectrum'.

Carcinoma, Squamous Cell↗

Fission yeast Rng3p: an UCS-domain protein that mediates myosin II assembly during cytokinesis.

Cell division in many eukaryotes, including the fission yeast Schizosaccharomyces pombe, utilizes a contractile actomyosin ring. In S. pombe, the actomyosin ring is assembled at the medial cortex upon entry into mitosis and constricts at the end of anaphase to guide the centripetal deposition of the septum. Despite identification of several structural components essential for actomyosin ring assembly, the interdependencies between these gene-products in the process of ring assembly are unknown. This study investigates the role of Rng3p, a member of the UCS-domain containing protein family (Unc-45p, Cro1p, She4p), in actomyosin ring assembly. Null mutants in rng3 resemble deletion mutants in the type II myosin heavy chain (myo2) and rng3(ts) mutants show strong negative interactions with the myo2-E1 mutant, suggesting that Rng3p is involved in modulating aspects of type II myosin function. Interestingly, a green fluorescent protein (GFP) tagged Rng3p fusion is detected at the division site in the myo2-E1 mutant, but not in other myo2-alleles, wild-type cells or in 18 other cytokinesis mutants. Assembly and maintenance of Rng3p at the division site in the myo2-E1 mutant requires F-actin. Rng3p is also required for the proper assembly of Myo2p and F-actin into a functional actomyosin ring but is not necessary for their accumulation at the division site. We conclude that Rng3p is a novel component of the F-actin cytoskeleton essential for a late step in actomyosin ring assembly and that it might monitor some aspect of type II myosin assembly during actomyosin ring construction.

Actomyosin↗

Administration of sevoflurane and isoflurane prior to prolonged global ischemia improves heart function in isolated rat heart.

BACKGROUND: The Langendorff model was used to determine whether pretreatment with sevoflurane, isoflurane, or ischemic preconditioning (IP) could protect the myocardium of rats against global ischemia. METHODS: After 15-min perfusion, each isolated heart was assigned to (1) CONTROL GROUP: no pretreatment, (2) Sevoflurane group: 20-min exposure of 1.7% sevoflurane prior to ischemia, (3) Isoflurane group: exposure of 1.4% isoflurane prior to ischemia, or (4) IP group: two 5-min ischemic periods separated by 5-min perfusion. Following pretreatment, each heart was exposed to 20-min global normothermic ischemia followed by 60-min reperfusion. Heart rate (HR), left ventricular end-diastolic pressure (LVEDP), left ventricular developed pressure (LVDP), HR x LVDP, left ventricular contractility (+dLVP/dt), and coronary flow were recorded continuously. Myocardial damage was assessed by hematoxylin and eosin (H&E) staining. RESULTS: No significant differences (P > 0.05) in hemodynamic variables were recorded among the four groups before the experiment. After ischemia during reperfusion, sevoflurane, isoflurane and IP pretreated hearts recovered left ventricular function significantly better than control hearts. After 60-min reperfusion, +dLVP/dt recovered to 6.84 +/- 1.06%, 23.3 +/- 4.80%, 42.3 +/- 3.16%, and 59.6 +/- 5.75% of baseline values respectively for control, sevoflurane, isoflurane and IP groups. HR x LVDP recovered to 8.9 +/- 1.7%, 27.9 +/- 6.42%, 38.7 +/- 2.78%, and 59.6 +/- 3.98% respectively. H&E staining supported the hemodynamic data in that hearts pretreated with sevoflurane, isoflurane and IP showed significantly less ischemic damage when compared to control hearts. CONCLUSIONS: Our study shows pretreatment with sevoflurane or isoflurane provided moderate protection to the isolated heart against prolonged periods of global ischemia.

Anesthetics, Inhalation↗

Gene therapy: a novel method for the treatment of myocardial ischemia and reperfusion injury--mini-review.

Myocardial ischemia and reperfusion injury (MI/R) represents important sequelae of clinical events. Historically, a number of approaches including, surgical intervention, pharmacological therapy and physical exercise regimes have been prescribed for the treatment of patients with cardiovascular disease. Recently, however, attention has focused upon more novel approaches using gene-based therapies to treat cardiovascular and MI/R. This mini-review will examine the role that heat shock proteins (HSP), in particular the HSP70 family, and the antiapoptotic protein Bcl-2 play in myocardial protection. Also examined in this review are several techniques including adenovirus and Japan-Liposomal method for delivering genes into the myocardium.

Genes, bcl-2↗

Eukaryotic initiation factor 4B from wheat and Arabidopsis thaliana is a member of a multigene family.

Clones of eukaryotic initiation factor (eIF) 4B from wheat and Arabidopsis thaliana were obtained from cDNA and genomic libraries. The exon/intron organization of the genes from wheat and A. thaliana is very similar. The deduced amino acid sequences for the wheat and Arabidopsis eIF4B proteins showed overall similarity to each other, but very little similarity to eIF4B from other eukaryotes. The recombinant form of eIF4B supports polypeptide synthesis in an in vitro translation system and reacts with antibodies to native wheat eIF4B. In contrast to mammalian eIF4B and eIF4A, the combination of wheat eIF4B and eIF4A does not stimulate RNA-dependent ATP hydrolysis activity; however, wheat eIF4B does stimulate eIF4F and eIF4A RNA-dependent ATP hydrolysis activity. Interestingly, eIF4B does not stimulate eIF(iso)4F and eIF4A hydrolysis activity. Gel filtration experiments indicate wheat eIF4B, like its mammalian counterpart, self-associates to form a homodimer.

Amino Acid Sequence↗

Acquired perforating dermatosis in diabetes mellitus: an unusual case.

A case of elastosis perforans serpiginosa in a patient who presented with insulin-dependent diabetes mellitus secondary to pancreatic insufficiency in a background of common variable immunodeficiency and endocrinopathy, as evidenced by pernicious anaemia and growth hormone deficiency, is described. In acquired perforating dermatosis occurring in patients with diabetes or renal failure, there is a spectrum of changes that may show an overlap of histological features of the four classic perforating diseases. The biopsy changes of the patient described in the present study most closely resembled those of elastosis perforans serpiginosa.

Adolescent↗

Clinical manifestations and outcomes in 17 cases of Stevens-Johnson syndrome and toxic epidermal necrolysis.

The clinical features and outcomes of 17 patients with Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) were retrospectively reviewed. There were 11 males and six females with an average age of 61.5 years. Ten patients with SJS (seven males, three females) and seven patients with TEN (four males, three females) were identified. Antibiotics, mainly beta-lactams, were the most common cause of SJS/TEN in this series. The mean skin loss in TEN was 45.7% total body surface area in contrast to the lesser skin loss (< 10%) observed in three patients with SJS. Complications included septicaemia, pneumonia and multi-organ failure, mainly in the TEN group. Two patients died from TEN-related complications and one patient with SJS died from unrelated causes. Ocular involvement and skin pigmentary changes represented the most significant long-term sequelae.

Adult↗

Integrins at the neuromuscular junction are important for motoneuron survival.

During development motoneurons depend on target contact for their survival. Following injury to the sciatic nerve in neonatal rats, a large proportion of motoneurons die. However, the same injury inflicted at 5 days of age results in no loss of motoneurons. This critical period of postnatal development coincides with the time during which there is a significant increase in the release of transmitter from the nerve terminals at the neuromuscular junction. We have proposed that the role of the target muscle cell during this period is to induce this up-regulation of transmitter release from motor nerve terminals. It has been shown that stretch-induced increase in transmitter release from frog motor nerve terminals is accomplished via an integrin-dependent mechanism. In this study we examined the role of integrins at the rat neuromuscular junction in motoneuron survival. We found that blocking integrin binding at the developing neuromuscular junction delayed the increase in choline acetyltransferase activity that normally takes place during the early postnatal period, and resulted in motoneuron death. Furthermore, the maturation of those motoneurons that survived was delayed so they remained susceptible to subsequent nerve injury. These results support the possibility that integrins, by their involvement in modulating transmitter release, can influence motoneuron survival.

Animals↗

Microcirculatory response to halothane and isoflurane anesthesia.

Microcirculatory hemodynamics are often used to monitor tissue and organ survival. This study investigated the effect of halothane and isoflurane anesthesia on peripheral microcirculation using the cremaster muscle during intravital microscopy. Twenty-three Sprague-Dawley rats were studied in four groups. Two groups served as controls and did not undergo flap isolation but did receive halothane (N = 6) or isoflurane (N = 5). After induction with a single dose of intraperitoneal pentobarbital (40 mg per kilogram), rats were ventilated with either 2 minimum alveolar concentration (MAC) halothane or 2 MAC isoflurane. Esophageal temperature, electrocardiography, central venous pressure, mean arterial pressure, and blood gases were measured over 4 hours. In groups receiving surgery with either halothane (N = 6) or isoflurane (N = 6), the cremaster muscle was isolated on the neurovascular pedicle. Microcirculatory responses to both halothane and isoflurane anesthesia were evaluated by measuring red blood cell (RBC) velocity, vascular diameters in arterioles (A1, A2-1, A2-2, and A3) and the main venule (V1), functional capillary perfusion, and leukocytic endothelial interactions in postcapillary venules (rolling, adherent, and transmigrating leukocytes). Hemodynamic variables were compared among all four groups, and microcirculatory variables were compared between the two surgical groups. During isoflurane anesthesia in animals with flaps, significantly higher (p < 0.05) RBC velocities were recorded in arterioles A1 (24.4%), A2-2 (28.2%), and A3 (17.4%). Capillary perfusion was significantly higher in animals with flaps and halothane anesthesia (17.8%; p < 0.05). The number of rolling leukocytes (39.4%) was significantly higher during isoflurane anesthesia in animals with flaps (p < 0.05). Better flow hemodynamics in the peripheral microcirculation were seen during halothane anesthesia, and were confirmed by greater functional capillary perfusion and fewer activated leukocytes. In the isoflurane group, RBC velocity alone cannot serve as an indicator of microcirculatory function.

Anesthesia, General↗

2-year clinical performance of a resin-modified glass ionomer sealant.

PURPOSE: To compare the 2-year clinical performance of an experimental resin-modified glass ionomer cement sealant (K-512 = Fuji III LC) with that of a light-cured resin-based sealant (Delton Opaque) in young adults: MATERIALS AND METHODS: 14 subjects with 47 K-512 and 41 Delton sealants were recalled at 2 years for clinical examination, photographs after enamel etching, impressions and radiographs. RESULTS: K-512 showed 0% complete retention, 62% partial retention, and 38% nil retention. The corresponding percentages for Delton were 32%, 58% and 10%, respectively. There was one instance of fissure caries for K-512 and three for Delton. Sealants deemed to need retreatments because of retention failures were 62% for K-512 and 34% for Delton. The K-512 sealants continued to darken over the study, many becoming slightly darker than the sealed teeth.

Acid Etching, Dental↗