Biomedical subjects

C N Chen

Publications and source records attributed to C N Chen.

At least 19 recordsLinked to original sources

PubMed2006

Short-term effects of hyposmotic shock on Na+/K+ -ATPase expression in gills of the euryhaline milkfish, Chanos chanos.

Changes in expression of gill Na+/K+ -ATPase (NKA) on a short-term (96 h) time-course following hyposmotic shock (direct transfer to fresh water) of the euryhaline, marine milkfish were studied on gene, protein, and cell levels in this paper. Plasma osmolality and [Na+] responded with rapid declines in 3 h post-transfer yet, thereafter, remained constant. Plasma [Cl-] gradually fell to a significantly lower level at 6 h post-transfer. Gills responded to hyposmotic shock by a dual phase enhancement of NKA activity and protein abundance; (a) Before 24 h: NKA activity increased as early as 3 h and reached a maximum level from 6 to 12 h post-transfer coincided with the sustained lower levels of plasma osmolality, [Na+], and [Cl-] since 3 h post-transfer. This was followed by a gradual rise in alpha-subunit protein levels that peaked at 12 h post-transfer. Meanwhile, alpha-mRNA of NKA did no show significant change. (b) After 24 h: NKA activity as well as the amounts of alpha-subunit mRNA and protein increased significantly. Direct freshwater transfer induced a prompt and significant decrease of NKA immunoreactive (NKIR) cell abundance in filaments before 24 h, followed by a significant increase after 24 h due to their development in filaments and lamellae. Increased number of NKIR cells after 24 h of hyposmotic shock may occur in conjunction with rise of NKA activity as well as alpha-subunit mRNA and protein abundance. In conclusion, milkfish is able to avoid an excessive drop in plasma ions immediately upon hyposmotic shock and maintain plasma ions on a marginal lower level in fresh water. Notably, the initial increase in NKA activity (adjustive phase; 3-12 h) and delayed increase in NKA mRNA and protein abundance (regulatory phase; 48-96 h) indicate the importance of a higher level of the gill enzyme in milkfish upon hyposmotic shock.

Animals↗

PubMed2005

Calreticulin expression in neuroblastoma--a novel independent prognostic factor.

BACKGROUND: Calreticulin (CRT), an endoplasmic reticulum protein, has been reported to be essential for the differentiation of neuroblastoma (NB) cells, suggesting that CRT may affect the tumor behavior of neuroblastoma. The aim of this study was to evaluate the association of clinicopathologic factors and patient survival with the expression of CRT in patients with NB. PATIENTS AND METHODS: Sixty-eight NBs were investigated by immunohistochemical staining against CRT, and were divided into positive and negative immunostaining groups. Correlations between calreticulin expression, various clinicopathologic and biologic factors, and patient survival were studied. In seven tumor samples, CRT mRNAs and proteins were evaluated with real-time PCR and western blot, respectively, and correlated with immunohistochemical findings. RESULTS: Among 68 NBs, 32 (47.1%) showed positive CRT expression. Positive CRT immunostaining strongly correlated with differentiated histologies, as well as known favorable prognostic factors such as detected from mass screening, younger age (< or =1 year) at diagnosis and early clinical stages, but inversely correlated with MYCN amplification. Kaplan-Meier analysis revealed that NB patients with CRT expression did have better survival. Multivariate analysis demonstrated CRT expression to be an independent prognostic factor. Moreover, CRT expression also predicted better survival in patients with advanced-stage NBs, and its absence predicted poorer survival in patients whose tumor had no MYCN amplification. The amount of CRT mRNAs and proteins in NB tumor samples tested correlated well with the immunohistochemical expressions. CONCLUSIONS: CRT expression correlates with the differentiation of NB and predicts favorable survival, thereby suggesting CRT to be a useful indicator for planning treatment of NB.

Biomarkers, Tumor↗

PubMed2003

The expression of gill Na, K-ATPase in milkfish, Chanos chanos, acclimated to seawater, brackish water and fresh water.

Juvenile milkfish Chanos chanos (Forsskål, 1775) were transferred from a local fish farm to fresh water (FW; 0 per thousand ), brackish water (BW; 10 per thousand, 20 per thousand ) and seawater (SW; 35 per thousand ) conditions in the laboratory and reared for at least two weeks. The blood and gill of the fish adapted to various salinities were analyzed to determine the osmoregulatory ability of this euryhaline species. No significant difference was found in plasma osmolality, sodium or chloride concentrations of milkfish adapted to various salinities. In FW, the fish exhibited the highest specific activity of Na, K-ATPase (NKA) in gills, while the SW group was found to have the lowest. Relative abundance of branchial NKA alpha-subunit revealed similar profiles. However, in contrary to other euryhaline teleosts, i.e. tilapia, salmon and eel, the naturally SW-dwelling milkfish expresses higher activity of NKA in BW and FW. Immunocytochemical staining has shown that most Na, K-ATPase immunoreactive (NKIR) cells in fish adapted to BW and SW were localized to the filaments with very few on the lamellae. Moreover, in FW-adapted milkfish, the number of NKIR cells found on the lamellae increased significantly. Such responses as elevated NKIR cell number and NKA activity are thought to improve the osmoregulatory capacity of the milkfish in hyposaline environments.

Acclimatization↗

PubMed2001

Stability of a biological tissue fixed with a naturally occurring crosslinking agent (genipin).

The study was undertaken to investigate the stability of a biological tissue fixed with a naturally occurring crosslinking agent (genipin) at distinct elapsed storage durations. The glutaraldehyde-fixed counterpart was used as a control. Porcine pericardia procured from a slaughterhouse were used as raw materials. After fixation, the fixed tissues were sterilized in a graded series of ethanol solutions and thoroughly rinsed in phosphate buffered saline for 1 day, and then stored in a jar containing sterilized water. The samples were taken out and tested for their stability during the durations of 1day through 6 months after storage. The stability of each study group was tested by measuring its tensile strength, free-amino-group content, and denaturation temperature. Additionally, the cytotoxicity of each test sample and its corresponding storage solution were investigated in vitro using 3T3 fibroblasts. The results were examined using a microscope and 3-(4,5-dimethylthiazol-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. It was found that the stability of the genipin-fixed tissue during storage was superior to its glutaraldehyde-fixed counterpart. The differences in stability between the genipin- and glutaraldehyde-fixed tissues during storage may be caused by their differences in crosslinking structure. There was no apparent cytotoxicity for both the genipin-fixed tissue and its corresponding storage solution throughout the entire course of the study, whereas significant cytotoxicity was observed for both the glutaraldehyde-fixed tissue and its storage solution. However, the cytotoxicity of the glutaraldehyde-fixed tissue decreased with increasing elapsed storage duration, whereas that of its corresponding storage solution increased. This suggested that the toxic residues remaining in the glutaraldehyde-fixed tissue leached out slowly into its corresponding storage solution during the course of storage.

3T3 Cells↗

PubMed2001

Early colonic carcinoma with extensive lymph node metastases: case report and review of literature.

An 81-year-old woman had an early carcinoma invading focally into the upper submucosa of the middle-transverse colon, which was accompanied by extensive lymph node metastases and resulted in a poor prognosis. Although her tumor was small and flat, a rim of pale yellow-speckled mucosa adjacent to the tumor enabled its earlier detection. To further study the exceptional lymph node metastases we studied the expression of intestinal trefoil factor and sialyl Tn antigen immunohistochemically on the resected specimen. Their simultaneous expression in lymph node metastasis further supports the aggressive nature of this tumor.

Adenocarcinoma↗

PubMed2001

Effects of heparin immobilization on the surface characteristics of a biological tissue fixed with a naturally occurring crosslinking agent (genipin): an in vitro study.

Heparinized biomaterials have been used to manufacture blood-contacting prostheses. The present study was intended to characterize the surface properties of a genipin-fixed biological tissue immobilized with heparin using the methods of ionic binding (the /h-i tissue) or covalent binding via multi-point attachment (the /h-m tissue) or end-point attachment (the /h-e tissue). The surface characteristics of test tissues evaluated were water contact angle, surface tension, protein adsorption, platelet adhesion, and cellular compatibility. Nonheparinized and the glutaraldehyde-fixed counterparts were used as controls. It was found that immobilization of heparin on the glutaraldehyde- and genipin-fixed tissues increased their hydrophilicity and surface tension and suppressed their mole ratio of adsorbed fibrinogen to adsorbed albumin and the amount of platelets adhered. Among the heparinized tissues, the /h-m tissue was more hydrophobic and had a higher mole ratio of adsorbed fibrinogen to adsorbed albumin and a greater amount of platelets adhered than the /h-i and /h-e tissues. In general, the surface characteristics of the /h-i tissue were comparable to the /h-e tissue. However, it is known that the ionically immobilized heparin may be displaced from the surface by an ion-exchange mechanism when exposed to blood. There were no significant differences in hydrophilicity, surface tension, the mole ratio of adsorbed fibrinogen to adsorbed albumin, and the amount of platelet adhesion between the glutaraldehyde- and genipin-fixed tissues in comparison with their respective counterparts. However, the cellular compatibility of the genipin-fixed tissues with or without heparinization was significantly superior to its glutaraldehyde-fixed counterparts.

Adsorption↗

PubMed2001

Noninvasive assessment of laryngeal phonation function using color Doppler ultrasound imaging.

Color Doppler imaging (CDI) was used to identify the morphology of vocal folds (VF) and to quantify the tissue horizontal displacement velocity (HDV) in the vibrating portion of VF. Mucosal HDV that gives an estimate of the stiffness of the VF cover is very important clinically. The VF and its cover were shown to be very hypoechoic and not adequately visible in B-scan image. However, in this study, we found that the structure of the true VF, especially the mucosa and the superficial layer of the lamina propria, the so-called "cover," can be easily identified and evaluated using CDI. The mean VF displacement velocity was measured by decoding the pseudocolor codes of the ultrasound (US) image at the vibrating sites. The mucosal mean HDV obtained from 10 normal men of age 34 +/- 8 years phonating at their most comfortable pitch and intensity (98 +/- 12 Hz, 55-65 dB) was about 68 +/- 10 cm/s, which agreed reasonably with the literature. Therefore, the CDI could be used as a potential tool for assessing the phonation function in the larynx nonintrusively.

Adult↗

PubMed2001

The stress- and abscisic acid-induced barley gene HVA22: developmental regulation and homologues in diverse organisms.

Abscisic acid (ABA) induces the expression of a battery of genes in mediating plant responses to environmental stresses. Here we report one of the early ABA-inducible genes in barley (Hordeum vulgare L.), HVA22, which shares little homology with other ABA-responsive genes such as LEA (late embryogenesis-abundant) and RAB (responsive to ABA) genes. In grains, the expression of HVA22 gene appears to be correlated with the dormancy status. The level of HVA22 mRNA increases during grain development, and declines to an undetectable level within 12 h after imbibition of non-dormant grains. In contrast, the HVA22 mRNA level remains high in dormant grains even after five days of imbibition. Treatment of dormant grains with gibberellin (GA) effectively breaks dormancy with a concomitant decline of the level of HVA22 mRNA. The expression of HVA22 appears to be tissue-specific with the level of its mRNA readily detectable in aleurone layers and embryos, yet undetectable in the starchy endosperm. The expression of HVA22 in vegetative tissues can be induced by ABA and environmental stresses, such as cold and drought. Apparent homologues of this barley gene are found in phylogenetically divergent eukaryotic organisms, including cereals, Arabidopsis, Caenorhabditis elegans, man, mouse and yeast, but not in any prokaryotes. Interestingly, similar to barley HVA22, the yeast homologue is also stress-inducible. These observations suggest that the HVA22 and its homologues encode a highly conserved stress-inducible protein which may play an important role in protecting cells from damage under stress conditions in many eukaryotic organisms.

Abscisic Acid↗

PubMed2001

Clinicopathologic association of cyclooxygenase 1 and cyclooxygenase 2 expression in gastric adenocarcinoma.

OBJECTIVE: To evaluate the association of clinicopathologic factors and prognostic value with the expression of cyclooxygenase 1 and 2 in patients with gastric adenocarcinoma. SUMMARY BACKGROUND DATA: Epidemiologic studies have indicated that nonsteroidal antiinflammatory drugs reduce the risk of colon cancer by as much as 40% and also decrease the risk of gastric cancer. Recently, gastric cancer was found to express constitutive cyclooxygenase 1 and inducible cyclooxygenase 2 isoenzymes. Nonsteroidal antiinflammatories, which may function as cyclooxygenase inhibitors, inhibited the growth of gastric cancer cells. These two isoenzymes' expressions associated with traditional clinicopathologic factors have not been fully evaluated, and their prognostic value for determining survival in patients remains to be clarified. METHODS: Seventy-one specimens resected from patients with gastric adenocarcinoma were investigated by immunohistochemical stain against cyclooxygenase 1 and 2. The 71 specimens were divided into stain-positive and stain-negative groups. Correlations between cyclooxygenase 1 and 2 expression, various clinicopathologic factors (including vascular invasion and Helicobacter pylori infection), and prognosis were studied. RESULTS: The cyclooxygenase 2-positive group was significantly correlated with vascular invasion and H. pylori infection by univariate and multivariate analysis. In patients with cyclooxygenase 2-positive cancer, the prognosis was significantly poorer than in those with cyclooxygenase 2-negative cancer. However, multivariate analysis showed that vascular invasion, serosal invasion, and lymph node metastasis were independent prognostic factors for patients with gastric cancer, but cyclooxygenase 2 expression was not. There was no significant correlation between cyclooxygenase 1 expression and clinicopathologic factors and prognosis. CONCLUSIONS: Upregulated cyclooxygenase 2 expression was associated with H. pylori infection in gastric cancer and was also strongly correlated with positive vascular invasion, which was an independent prognostic factor for poorer survival in this study. The usefulness of cyclooxygenase 2 inhibitors in the prevention or treatment of gastric cancer remains undetermined but deserves further investigation.

Adenocarcinoma↗

PubMed2000

Influence of pluronic F-68 on dissolution and bioavailability characteristics of multiple-layer pellets of nifedipine for controlled release delivery.

A multiple-layer design of pellets for nifedipine was developed using pluronic F-68 to enhance dissolution rate. The influence of ratios of nifedipine in the inner layer to that in the outer layer, the ratios of pluronic F-68 to nifedipine in the solid dispersion, and the thickness of the control membrane on dissolution characteristics were investigated. With an increasing ratio of pluronic F-68 to nifedipine, the dissolution rate of nifedipine was gradually promoted and the extent of release was enhanced as well. DSC thermograms illustrate the gradual disappearance or broadening of the nifedipine melting peak with the presence of pluronic F-68. The decrease of the nifedipine ratio in the inner layer and the increase of the ratio of pluronic F-68 to nifedipine in the outer layer can enhance the release of nifedipine. With a fixed nifedipine ratio of 1.5 between the inner layer and the outer layer, increasing the ratio of pluronic F-68 to nifedipine in the outer layer significantly increased the initial release rate of nifedipine. By increasing the nifedipine ratio of the inner layer to the outer layer to 1:1, the increase of coating percentage referenced to the total weight decreased the release rate of nifedipine from the inner layer. The pharmacokinetic bioequivalence between the test product (Cardilate, N-6) and Coracten was found with a multiple-dose oral administration of 20 mg in 12 healthy, normal Chinese male volunteers.

Adult↗

PubMed2000

Color Doppler vascularity index can predict distant metastasis and survival in colon cancer patients.

The purpose of this study was to investigate the clinical usefulness of the color Doppler vascularity index (CDVI) in patients with colon cancer before surgery. Forty-four patients with sonographically visible tumor mass of colon cancer were investigated. The CDVI of each tumor was determined using transabdominal color Doppler ultrasound. The CDVI was defined as the ratio of the number of the colored pixels within a tumor section to the number of total pixels in that specific tumor section and was calculated by using Encomate software (Electronic Business Machine Co. Ltd., Taipei, Taiwan). The correlation between the CDVI and clinicopathological factors, mode of recurrence, and patient survival was studied. For comparison, microvessel density (the mean number of microvessels in three areas of highest vascular density at x200 magnification) of the tumors of these 44 patients was also evaluated by using immunohistochemical staining of surgical specimens with anti-CD34. The microvessel density was not correlated with Dukes' classification, clinicopathological factors, and survival. The CDVI was significantly higher in the patients with lymph node metastases and vascular invasion than in those without such metastases and invasion (P = 0.006 and P = 0.0098, respectively). Moreover, in patients with a high CDVI (> 15%) and positive vascular invasion, survival was significantly poorer than in those with low CDVI (< or = 15%) and negative invasion (P = 0.0037 and 0.0039, respectively). Multivariate analysis indicated that liver metastasis, vascular invasion, and CDVI are independent prognostic factors in the patients with colon cancer. According to the mode of recurrence in 36 patients who underwent curative resection, the frequency of the distant organ recurrence was significantly higher in the high CDVI group (40%) than in the low CDVI group (0%). The CDVI is a good preoperative indicator of recurrence and patient survival in colon cancer. Thus, the CDVI may be helpful in stratifying patients for adjuvant therapy.

Adult↗

PubMed2000

In vitro surface characterization of a biological patch fixed with a naturally occurring crosslinking agent.

The study was designed to characterize the surface properties (including water contact angle, surface tension, protein adsorption, platelet adhesion, and cellular compatibility) of a biological patch fixed with genipin, a naturally occurring crosslinking agent. Fresh and glutaraldehyde-fixed counterparts were used as controls. It was found that both glutaraldehyde and genipin are effective crosslinking agents for biological tissue fixation. Fixation of biological tissue with glutaraldehyde or genipin significantly increased its hydrophilicity and surface tension and reduced its mol ratio of adsorbed fibrinogen to adsorbed albumin as well as the amount of adhered platelet. There were no significant differences in hydrophilicity, surface tension, the mole ratio of adsorbed fibrinogen to adsorbed albumin, and the amount of platelet adhesion between the glutaraldehyde- and genipin-fixed tissues. However, the cellular compatibilities of fresh and the genipin-fixed tissues were significantly superior to the glutaraldehyde-fixed tissue.

3T3 Cells↗

PubMed1999

Crosslinking characteristics and mechanical properties of a bovine pericardium fixed with a naturally occurring crosslinking agent.

Currently available crosslinking agents used in fixing bioprostheses are all highly (or relatively highly) cytotoxic, which may induce an adverse inflammatory reaction in vivo. It is therefore desirable to provide a crosslinking agent that is of low cytotoxicty and may form stable and biocompatible crosslinked products. To achieve this goal, a naturally occurring crosslinking agent-genipin-was used by our group to fix biological tissues. Genipin may be obtained from its parent compound, geniposide, which may be isolated from the fruits of Gardenia jasminoides Ellis. In our previous studies, it was found that the cytotoxicity of genipin is significantly lower than both glutaraldehyde and an epoxy compound. Also, it was shown that genipin can form stable and biocompatible crosslinked products. The present study further investigates the crosslinking characteristics and mechanical properties of a genipin-fixed bovine pericardium. Fresh and glutaraldehyde- and epoxy-fixed counterparts were used as controls. It was found that the denaturation temperatures of the glutaraldehyde- and genipin-fixed tissues were significantly greater than the epoxy-fixed tissue, although their fixation indices were comparable. The mechanical properties of fresh bovine pericardium are anisotropic. However, fixation tended to eliminate tissue anisotropy. The tendency in the elimination of tissue anisotropy for the genipin-fixed tissue was more remarkable than for the glutaraldehyde- and epoxy-fixed tissues. In addition, the genipin-fixed tissue had the greatest ultimate tensile strength and toughness among all the fixed tissues. Distinct patterns in rupture were observed in the study: The torn collagen fibers of the genipin- and glutaraldehyde-fixed tissues appeared to be bound together, while those of fresh and the epoxy-fixed tissues stayed loose. The results obtained in the study suggests that tissue fixation in glutaraldehyde, epoxy compound, and genipin may produce distinct crosslinking structures. The differences in crosslinking structure may affect the crosslinking characteristics and mechanical properties of the fixed tissues.

Animals↗

PubMed1999

Mechanical properties of a porcine aortic valve fixed with a naturally occurring crosslinking agent.

The study investigates the mechanical properties of porcine aortic valve leaflets fixed with a naturally occurring crosslinking agent, genipin, at distinct pressure heads. Fresh and the glutaraldehyde-fixed counterparts were used as controls. Subsequent to fixation, the changes in leaflet collagen crimps and its surface morphology were investigated by light microscopy and scanning electron microscopy (SEM). Also, the crosslinking characteristics of each studied group were determined by measuring its fixation index and denaturation temperature. In the mechanical testing, tissue strips made from each studied group were examined in both the circumferential and radial directions. Histological and SEM comparisons between fresh porcine aortic valve leaflet and those fixed at medium or high pressure revealed that the following changes may occur: elimination of the natural collagen crimping, and extensive loss of the endothelial layer. The denaturation temperatures of the glutaraldehyde-fixed leaflets were significantly greater than the genipin-fixed leaflets; however, their fixation indices were comparable. Generally, fixation pressure did not affect the crosslinking characteristics of the genipin- and glutaraldehyde-fixed leaflets. It was found that fixation of porcine aortic valves in genipin or glutaraldehyde did not alter the mechanical anisotropy observed in fresh valve leaflets. This indicated that the intramolecular and intermolecular crosslinks introduced into the collagen fibrils during fixation is of secondary importance to the presence of structural and mechanical anisotropy in fresh leaflet. Tissue fixation in genipin or glutaraldehyde may produce distinct crosslinking structures. However, the difference in crosslinking structure between the genipin- and glutaraldehyde-fixed leaflets did not seem to cause any significant discrepancies in their mechanical properties when compared at the same fixation pressure. Nevertheless, regardless of the crosslinking agent used, changes in mechanical properties and ruptured patterns were observed when the valve leaflets were fixed at distinct pressures.

Animals↗

PubMed1999

Monte Carlo dynamics in global optimization.

Several very different optimization problems are studied by using the fixed-temperature Monte Carlo dynamics and found to share many common features. The most surprising result is that the cost function of these optimization problems itself is a very good stochastic variable to describe the complicated Monte Carlo processes. A multidimensional problem can therefore be mapped into a one-dimensional diffusion problem. This problem is either solved by direct numerical simulation or by using the Fokker-Planck equations. Above certain temperatures, the first passage time distribution functions of the original Monte Carlo processes are reproduced. At low temperatures, the first passage time has a path dependence and the single-stochastic-variable description is no longer valid. This analysis also provides a simple method to characterize the energy landscapes.

Crystallography, X-Ray↗

PubMed1998

Glypican 3 and glypican 4 are juxtaposed in Xq26.1.

Recently, we have shown that mutations in the X-linked glypican 3 (GPC3) gene cause the Simpson-Golabi-Behmel overgrowth syndrome (SGBS; ). The next centromeric gene detected is another glypican, glypican 4 (GPC4), with its 5' end 120763bp downstream of the 3' terminus of GPC3. One recovered GPC4 cDNA with an open reading frame of 1668nt encodes a putative protein containing three heparan sulfate glycosylation signals and the 14 signature cysteines of the glypican family. This protein is 94.3% identical to mouse GPC4 and 26% identical to human GPC3. In contrast to GPC3, which produces a single transcript of 2.3kb and is stringently restricted in expression to predominantly mesoderm-derived tissues, Northern analyses show that GPC4 produces two transcripts, 3.4 and 4.6kb, which are very widely expressed (though at a much higher level in fetal lung and kidney). Interestingly, of 20 SGBS patients who showed deletions in GPC3, one was also deleted for part of GPC4. Thus, GPC4 is not required for human viability, even in the absence of GPC3. This patient shows a complex phenotype, including the unusual feature of hydrocephalus; but because an uncle with SGBS is less affected, it remains unclear whether the GPC4 deletion itself contributes to the phenotype.

Abnormalities, Multiple↗

PubMed1998

Generation of depth-perception information in stereoscopic nuclear magnetic resonance imaging by non-linear magnetic field gradients.

Stereoscopic NMR images have been produced in the past. However, because of the gradients are linear, only isometric projections can be produced, i.e., they do not carry correct depth-perception information. The resulting stereoscopic image will not have correct relative sizes at different depths. This paper gives an analysis of what perception information is needed and shows that it can be produced by a non-linear magnetic field gradient. The concept is exemplified by simulations and its implementation is demonstrated successfully by experiments. The depth-encoding gradient can be generated by static steel pieces or by current loops. The procedure can be incorporated into any existing hardware and pulse sequences, and has potential application in surgery.

Depth Perception↗

PubMed1998

HLA DR2 and DQ1 frequency among narcoleptic patients in Hong Kong Chinese.

Narcolepsy is a life-long crippling sleep disorder with significant physical and psychosocial impairments. Although its exact etiology and neuropathology is not clear, a strong association with specific human leucocyte antigen (HLA) subtype, particularly DR2 (DRw15) and DQw1 (DQw6), has been demonstrated across different ethnic groups including Caucasians and Japanese. The presence of 100% association with HLA DR2 in a series of Hong Kong Chinese narcoleptic patients has previously been reported. The report can now be extended, and as far as could be ascertained in the available subjects, all were HLA DQw1 (DQw6)-positive. This is concordant with the experiences of Japanese narcoleptic patients who are 100% HLA DR2- and DQw1-positive. However, the definitive account of the population prevalence of narcolepsy in Chinese could be determined only by a well-conducted epidemiological study with laboratory confirmation.

Adolescent↗