PubMed Health⌕ Search

Biomedical subjects

C C Cheung

Publications and source records attributed to C C Cheung.

At least 19 recordsLinked to original sources
PubMed2006

Experience sharing on the implementation of telehealth system in Hong Kong.

With the growth of the ageing population in Hong Kong, healthcare professionals believe that there will be a great demand of healthcare service at the community level. In 2000, the first prototype of telehealth system was developed, tested and validated by the School of Nursing, The Hong Kong Polytechnic University. With the advancement of information technology and inexpensive video- conference facility, an inter-clinic patient-centered healthcare information system has been evolved and used by a number of satellite clinics since 2003. In order to foster the importance of personal healthcare education at the community level, different versions of the telehealth system were designed and developed for school children and teenagers. Now the research team is focusing on the development of the pocket PC's version. Experience on the deployment of such technology-intensive system in healthcare was discussed in this paper.

Diffusion of Innovation↗
PubMed2002

Anti-Mta associated with three cases of hemolytic disease of the newborn.

The Mta antigen is a low-frequency red blood cell (RBC) surface antigen and is an established antigen of the MNSs blood group system. There has been one report of anti-Mta-induced hemolytic disease of the newborn (HDN) in the literature to date. We describe a family in which three children were affected by neonatal anemia. The clinical and hematologic findings were consistent with HDN, despite repeatedly negative direct antiglobulin tests (DAT) on cord RBCs. Serologic investigations showed that the mother's serum contained anti-Mta. The father and all three children phenotyped as Mta+, while the mother was Mta-. Adsorption and elution experiments gave results which suggested that anti-Mta may be implicated in recurrent HDN in this family.

Journal Article↗
PubMed2001

Relationships between tissue concentrations of polycyclic aromatic hydrocarbons and antioxidative responses of marine mussels, Perna viridis.

Local mussels, Perna viridis, were transplanted from a relatively clean site to various polluted sites in Hong Kong. After a 30-day field exposure, different antioxidant parameters including glutathione S transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), NADPH DT-diaphorase (DT-d), glutathione (GSH) and lipid peroxidation were quantified, and tissue concentrations of benzo[a]pyrene (B[a]P) as well as a total of five polycyclic aromatic hydrocarbons (PAHs) with potential carcinogenicity were determined for individual mussels. Results indicated that: (1) tissue concentrations of B[a]P and total PAHs from the same site were highly variable; (2) gill SOD, DT-d and lipid peroxidation showed no response to tissue pollutants; (3) the majority of the antioxidant parameters were induced by increasing tissue pollutant concentrations; and (4) amongst the various parameters, oxyradical scavenger GSH best correlated with tissue concentrations of pollutants.

Animals↗
PubMed2001

Distribution of galanin messenger RNA-expressing cells in murine brain and their regulation by leptin in regions of the hypothalamus.

Galanin is widely distributed throughout the mammalian brain and has been implicated in the regulation of food intake, metabolism and reproduction-functions that are also thought to be under the control of leptin. To investigate the possible role of galanin in mediating the physiological effects of leptin in the mouse, we had three experimental objectives: first, to map the distribution of galanin messenger RNA-expressing cells in the brain of the mouse; second, to assess the effects of leptin on galanin gene expression in areas of the brain thought to be involved in the regulation of body weight and reproduction; and third, to determine whether galanin neurons in these regions express leptin receptor messenger RNA. We found the pattern of galanin messenger RNA expression in the mouse brain to be similar, but not identical, to that in the rat. Leptin treatment (2microg/g for six days) significantly reduced cellular levels of galanin messenger RNA in the hypothalamic periventricular nucleus of leptin-deficient obese (ob/ob) mice (P<0.01) by approximately 30%; however, leptin did not appear to influence the expression of galanin in the arcuate or dorsomedial nucleus of the hypothalamus. Galanin-producing neurons in the arcuate, dorsomedial and periventricular nuclei did not appear to express leptin receptor messenger RNA (P>0.05). These results demonstrate that galanin distribution patterns in the mouse brain are comparable to other species and, yet, possess unique features. In addition, galanin-expressing neurons in the hypothalamic periventricular nucleus are targets for regulation by leptin; however, the effect of leptin on galanin gene expression is likely to be mediated indirectly, perhaps through either proopiomelanocortin- or neuropeptide Y-expressing cells in the hypothalamus.

Animals↗
PubMed2001

Immunohistochemical diagnosis of papillary thyroid carcinoma.

In thyroid, the diagnosis of papillary carcinoma (PC) is based on nuclear features; however, identification of these features is inconsistent and controversial. Proposed markers of PC include HBME-1, specific cytokeratins (CK) such as CK19, and ret, the latter reflecting a ret/PTC rearrangement. We applied immunohistochemical stains to determine the diagnostic accuracy of these three markers. Formalin-fixed, paraffin-embedded tissue from 232 surgically resected thyroid nodules included 40 hyperplastic nodules (NH), 35 follicular adenomas (FA), 138 papillary carcinomas (PC; 54 classical papillary tumors and 84 follicular variant papillary carcinomas [FVPC]), 4 follicular carcinomas (FC), 6 insular carcinomas (IC), 7 Hürthle cell carcinomas (HCC), and 2 anaplastic carcinomas (AC). HBME-1 and ret were negative in all NH and FA; some of these exhibited focal CK19 reactivity in areas of degeneration. Half of the FC and AC exhibited HBME-1 staining but no positivity for CK19 or ret. In PC, 20% of cases stained for all three markers. Classical PC had the highest positivity with staining for HBME-1 in 70%, CK19 in 80%, and ret in 78%. FVPC were positive for HBME-1 in 45%, for CK19 in 57%, and for ret in 63%; only 7 FVPC were negative for all three markers. The six IC exhibited 67% staining for HBME-1 and 50% positivity for CK19 and ret. The seven HCC had 29% positivity for HBME-1 and CK19, and 57% positivity for ret. This panel of three immunohistochemical markers provides a useful means of diagnosing PC. Focal CK19 staining may be found in benign lesions, but diffuse positivity is characteristic of PC. HBME-1 positivity indicates malignancy but not papillary differentiation. Only rarely are all three markers negative in PC; this panel therefore provides an objective and reproducible tool for the analysis of difficult thyroid nodules.

Adenocarcinoma, Follicular↗
PubMed2001

A reassessment of leptin's role in triggering the onset of puberty in the rat and mouse.

Leptin is an adipocyte-derived hormone that has been implicated to serve as a metabolic signal to the reproductive axis. The role of leptin in pubertal maturation, however, has been a much-debated topic. We have previously reported that leptin serves as a permissive signal to the onset of puberty in the female rat. In an attempt to further understand the mechanics of leptin during pubertal maturation in rodent species, we had three experimental objectives: first, to describe the temporal relationship of leptin with development in the male and female rat; second, to seek evidence for an increase in responsiveness of the neuroendocrine axis to leptin by assessing for possible changes in leptin receptor expression during pubertal developmental in the female rat; and, third, to reevaluate the possible role of leptin as a permissive signal to the onset of puberty in the mouse. We found that serum leptin levels remain relatively constant during the prepubertal and postpubertal stages of both sexes. In addition, we could not detect any significant developmental changes in leptin receptor gene expression in the hypothalamus of the female rat. Lastly, we corroborated our findings in the female rat that leptin reversed the delay in pubertal maturation secondary to food restriction but did not advance the onset of puberty in female mice. Together, these results suggest that leptin is not a metabolic trigger for the onset of puberty in the rodent; instead, leptin is one of several permissive factors, whose presence may be necessary but alone is not sufficient to initiate sexual maturation in these species.

Animals↗
PubMed2001

The spectrum and significance of primary hypophysitis.

Hypophysitis can present clinically as a mass lesion of the sella turcica. Secondary hypophysitis occurs in cases where a definite etiologic agent or process inciting the inflammatory reaction can be identified. In contrast, primary hypophysitis refers to inflammation confined to the pituitary gland with no identifiable etiologic associations. We report three cases of primary hypophysitis to illustrate the spectrum of three clinicopathological entities that encompass this disease: lymphocytic hypophysitis, granulomatous hypophysitis, and xanthomatous hypophysitis. Our three patients underwent surgery, with variable response. However, conservative, supportive treatment with or without surgical decompression is generally favored over aggressive and extensive surgical resection that results in hypopituitarism. We conclude that the optimal management of patients with hyophysitis requires a high index of suspicion before extensive surgical resection. Histological confirmation of the diagnosis of hypophysitis can be obtained by performing a biopsy or by requesting an intraoperative frozen section consultation.

Adult↗
PubMed2001

Analysis of ret/PTC gene rearrangements refines the fine needle aspiration diagnosis of thyroid cancer.

Papillary carcinoma (PC) represents the most common malignancy of the thyroid gland. Therefore, the assessment of fine needle aspiration biopsies of thyroid nodules rests heavily on the identification of nuclear features of PC. The ret/PTC oncogene, formed by several gene rearrangements, is specific for PC among thyroid tumors. In this study we examined thyroid aspirates for the presence of ret/PTC gene rearrangements by RT-PCR and Southern hybridization. We prospectively collected thyroid aspirates in Cytolyt solution and prepared slides for cytological examination using the ThinPrep method. All remaining material was then used for nucleic acid extraction with subsequent RT-PCR for the housekeeping gene PGK-1 to ensure ribonucleic acid integrity, for thyroglobulin to ensure the presence of follicular epithelial cells, and for the three most common ret/PTC gene rearrangements (ret/PTC-1, -2, and -3). The results of the first 73 cases with surgical follow-up were correlated with the cytological diagnosis and final histopathology. ret/PTC gene rearrangements were detected in 17 of 33 samples (52%) that were PC on histopathology; the presence of gene rearrangements was confirmed by molecular analysis of corresponding surgically resected frozen tissue. There were no false positives. The identification of ret/PTC gene rearrangements refined the diagnosis of PC in 9 of 15 specimens (60%) that would otherwise have been considered indeterminate and in 2 of 6 that were considered insufficient for cytological diagnosis. The results indicate that RT-PCR for ret/PTC is a specific marker that can be applied to fine needle aspiration biopsies and improves the diagnosis of malignancy when used as an adjunct to traditional cytology.

Biopsy, Needle↗
PubMed2001

The mind's eye.

Explore the source record for details and available documents.

Adenoma↗
PubMed2001

Extraskeletal Ewing sarcoma in a 77-year-old woman.

Extraskeletal Ewing sarcoma (EES) is a rare soft tissue tumor that is morphologically indistinguishable from Ewing sarcoma of bone. It is usually found in young people, but several cases have occurred in patients older than 50 years. The differential diagnoses include other small, blue round cell tumors (SBRCTs) and other members of the Ewing family of tumors such as the primitive neuroectodermal tumor. We present a case of EES in the left inguinal region of a 77-year-old woman. The tumor was distinguished from other SBRCTs by lack of immunoreactivity for epithelial, lymphoid, vascular, neuroendocrine, neural, histiocytic, and muscle markers. Primitive neuroectodermal tumor was excluded because of the lack of neural differentiation by histologic analysis, immunohistochemistry, and electron microscopy. Extraskeletal Ewing sarcoma was confirmed by characteristic features on histologic analysis, histochemistry, immunohistochemistry, and electron microscopy and by the presence of the t(11;22)(q24;q12) fusion transcript detected by reverse transcriptase-polymerase chain reaction. This case serves to remind the reader that EES is not a tumor that occurs exclusively in young patients.

Aged↗
PubMed2001

Biomarker studies on gold-lined sea bream (Rhabdosargus sarba) exposed to benzo[a]pyrene.

Gold-lined sea bream (Rhabdosargus sarba) were intraperitoneally injected with 35 mg/kg benzo[a]pyrene (in DMSO), with fish administered DMSO as the solvent control. Fish were sacrificed 3 days post injection and their livers dissected for the analysis of adenosine triphosphates (ATPase), glutathione-S-transferase (GST), DNA adducts and ethyoxyresorufin-O-deethylase (EROD). Exposure to B[a]P resulted in reduced ATPase activity, elevated GST activity and DNA adduct level, but no apparent change in EROD activity.

Adenosine Triphosphatases↗
PubMed2001

Orientation illusions and heart-rate changes during short-radius centrifugation.

Intermittent short-radius centrifugation is a promising countermeasure against the adverse effects of prolonged weightlessness. To assess the feasibility of this countermeasure, we need to understand the disturbing sensory effects that accompany some movements carried out during rotation. We tested 20 subjects who executed yaw and pitch head movements while rotating at constant angular velocity. They were supine with their main body axis perpendicular to earth gravity. The head was placed at the centrifuge's axis of rotation. Head movements produced a transient elevation of heart-rate. All observers reported head-contingent sensations of body tilt although their bodies remained supine. Mostly, the subjective sensations conform to a model based on semicircular canal responses to angular acceleration. However, some surprising deviations from the model were found. Also, large inter-individual differences in direction, magnitude, and quality of the illusory body tilt were observed. The results have implications for subject screening and prediction of subjective tolerance for centrifugation.

Adult↗
PubMed2000

Expression of prostate-specific antigen and human glandular kallikrein 2 in the thyroid gland.

Prostate-specific antigen (PSA) and human glandular kallikrein 2 (hK2) are two closely related kallikreins, primarily produced by the prostate. These serine proteases are now used as biomarkers for the diagnosis and management of prostate cancer. Until recently, PSA and hK2 were thought to be strictly expressed in the prostate; however, numerous studies confirmed their presence in various biological fluids as well as in many normal and malignant tissues. Using reverse transcription-polymerase chain reaction (RT-PCR), we screened RNA extracted from 26 different normal tissues and found that both genes are expressed in the thyroid. Subsequently, we analyzed 15 RNAs extracted from thyroid tissues (10 benign and 5 malignant lesions) and found that both kallikreins were expressed in five specimens (four benign lesions and one malignant). Sequencing of the PCR products confirmed the specificity of our experiments. Immunohistochemistry localized PSA in oxyphilic cells of thyroid tissue. These data confirm expression of both PSA and hK2 in thyroid tissue and suggest that oxyphils are the source of their production. The function of these two proteases in thyroid tissue is unknown.

Base Sequence↗
PubMed2000

Trail making across languages.

The effects of different language backgrounds on trail making tasks were examined in this study. The measures adopted were the Color Trails Test (CTT) and the Trail Making Test (TMT), the former being the culturally fair analogue of the latter. Eighty-four right-handed participants belonging to the Chinese-English Bilingual (CEB) and English Monolingual (EM) groups participated in this study. The results of between-group comparisons revealed no significant differences in performance on the two measures between our Chinese bilingual and English monolingual participants, except on the TMT-A. However, a within-group correlation indicated that performances on the TMT and CTT were highly correlated for the English sample, but not for the Chinese. These observations suggest that trail making tasks like the TMT and CTT are themselves generally fair across Chinese and English, but equivalence between them may be more language-specific. Furthermore, mastery of a language loaded on temporal sequencing like English may give an advantage in the completion of trail making tasks.

Adult↗
PubMed2000

Hyalinizing trabecular tumor of the thyroid: a variant of papillary carcinoma proved by molecular genetics.

Hyalinizing trabecular tumors of the thyroid are interesting but uncommon neoplasms. They have been classified as benign hyalinizing trabecular adenomas or malignant hyalinizing trabecular carcinomas. They share both epidemiologic and morphologic features with papillary carcinoma, and there has been much speculation about the relationship between these two entities. Because RET/PTC gene rearrangements are specific to papillary thyroid carcinoma, the authors examined the presence of RET/PTC-1, -2, and -3 in eight hyalinizing trabecular tumors using reverse transcription-polymerase chain reaction with Southern hybridization and immunohistochemistry. They detected the presence of a RET/PTC gene rearrangement in six of the eight hyalinizing trabecular tumors. This confirms the long-standing suspicion that hyalinizing trabecular tumors do indeed represent a morphologic variant of papillary carcinoma.

Adenoma↗
PubMed2000

Molecular basis off hurthle cell papillary thyroid carcinoma.

Among thyroid neoplasms, Hurthle cell tumors (HCTs) have traditionally been a distinct diagnostic category. Hurthle cell adenomas are encapsulated follicular lesions with benign behavior. Hurthle cell carcinomas exhibit unequivocal capsular and/or vascular invasion; they are aggressive tumors with a poor prognosis. Recently, Hurthle cell papillary thyroid carcinomas (PTCs) have been identified on morphological grounds. We hypothesize that a subset of HCTs represent PTC with clinical, histological, and immunohistochemical features based on specific molecular events. ret/PTC gene rearrangements give rise to novel oncogenes that are unique to PTC. We studied a group (n = 50) of HCTs for ret/PTC gene rearrangements. Tumors were examined for papillary differentiation by light microscopic evaluation of nuclear features, by RT-PCR for ret/PTC gene rearrangements, and by immunohistochemistry for ret. Among 24 noninvasive tumors, 13 contained ribonucleic acid for ret/PTC-1, -2, or -3, and 9 of these were immunoreactive for ret. Among 19 Hurthle cell carcinomas, 15 had focal nuclear hypochromasia with grooves and/or inclusions; expressed transcripts of ret/PTC-1, -2, or-3; and exhibited ret positivity. Tumors with ret/PTC gene rearrangements tended to have lymph node metastases rather than hematogenous spread. Our results indicate that a subset of HCTs exhibit features of PTC that are attributable to specific gene rearrangements, resulting in expression of ret/PTC oncogenes. These data support subclassification of HCTs into three groups: Hurthle cell adenomas, Hurthle cell carcinomas, and Hurthle cell PTC.

Adenocarcinoma, Papillary↗
PubMed1997

Assessment of tracheoesophageal speech in a tonal language. A prospective study.

BACKGROUND: Tracheoesophageal puncture followed by insertion of a voice prosthesis is an increasingly popular method for voice rehabilitation after total laryngectomy. OBJECTIVE: To perform a functional assessment of voice produced by means of the Blom-Singer valve in a tonal language (Cantonese). DESIGN: Prospective study. SETTING: Hospital referral center. MAIN OUTCOME MEASURE: A 5-point scoring scale was adopted for 15 test items of speech assessment grouped into 4 categories: phonatory skills, articulation, additional factors, and general judgment. The sum of the scores for the 15 items was the final speech score. The final speech score was rated as poor, satisfactory, or excellent if it was in the range of less than 30, 31 to 45, or 46 to 75, respectively. RESULTS: Forty-four users of the Blom-Singer valve who had undergone total laryngectomy and primary tracheoesophageal puncture were available for functional assessment. The final speech score was poor in 2 patients (5%), satisfactory in 4 (9%), and excellent in 38 (86%). CONCLUSION: Chinese patients can speak satisfactory tonal language with the Blom-Singer voice prosthesis.

Adult↗