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Biomedical subjects

D W Chan

Publications and source records attributed to D W Chan.

At least 127 records · Page 7Linked to original sources
PubMed1992

Hassles, life events, and health status among Chinese college students in Hong Kong.

Major life events and daily hassles were examined in a sample of 102 university undergraduates. While the major clusters of events were related to personal loss, life-style changes, family conflict, and personal insecurity, those of hassles were related to drudgery and uncontrollable environmental irritants, personal concerns, time and work management, minor routine expenses, and the dilemma of emigration. Using life events and hassles, and hassle clusters added significantly to the sensitivity of the concurrent prediction of undifferentiated and differentiated physical and psychological symptom criteria, and consistently showed better performance as predictors. However, the independent contributions of events and event clusters could hardly be discounted. The combined effects of major discrete and minor chronic stress on health status and the limitations of the present retrospective study were discussed.

Adolescent↗
PubMed1991

Capillary prolactin measurement for diagnosis of seizures.

Measurement of serum prolactin levels can be useful in the diagnosis of epilepsy, since prolactin levels often rise after seizures, but not after most imitators of epilepsy. Utility of the test is limited by the need to obtain blood 10 to 20 minutes after the episode. The present study documents the validity of prolactin measurements using capillary blood, which was obtained by the finger-stick method after a possible seizure and then applied to filter paper. Venous and capillary prolactin levels were determined 10 to 20 minutes after seizure-like episodes in 20 patients who were studied in an epilepsy monitoring unit. Venous and capillary prolactin values correlated, with a Pearson coefficient of 0.90. Using a criteria of any elevation above the laboratory upper limit of normal, capillary prolactin values correctly identified seizure versus pseudoseizure in 9 (100%) of 9 patients with generalized tonic-clonic seizures, in 5 (71%) of 7 patients with complex partial seizures, and 4 (100%) of 4 patients with pseudoseizures. Prolactin values were unaffected by leaving filter paper samples at room temperature for up to 1 week. This study suggests the utility of diagnostic capillary blood collection kits to assist in the diagnosis of epilepsy in outpatients.

Adult↗
PubMed1991

The potential utility of a rapid CK-MB assay in evaluating emergency department patients with possible myocardial infarction.

STUDY OBJECTIVES: To determine the sensitivity, specificity, and predictive values of a new rapid creatine kinase-MB (R-CK-MB) assay compared with a standard CK-MB (S-CK-MB) assay and to determine its potential use in the evaluation of emergency department patients with possible myocardial infarction. DESIGN: Retrospective patient identification with subsequent testing of excess sera for CK-MB and total CK using an identity-unlinked procedure. SETTING: Large, urban, teaching hospital ED. PARTICIPANTS: All adult patients with excess sera and one of several defined presentations chosen to identify those with possible myocardial ischemia or infarction. Patients with clearly documented noncardiac etiologies of their symptoms or signs were excluded. MAIN RESULTS: The sensitivity, specificity, and positive and negative predictive values of 271 patient specimens for the R-CK-MB assay compared with the S-CK-MB assay were 100%, 96.8%, 75.0%, and 100%, respectively. The R-CK-MB assay was positive for 32 patients (11.8%). Of these, eight (25.0%) were admitted to unmonitored beds, and five (15.6%) were discharged home. All of these 13 patients had initial ECGs without evidence of ischemia or infarction. On follow-up, at least eight of the 13 had evidence of infarction. CONCLUSION: The R-CK-MB assay demonstrated high sensitivity and specificity compared with the S-CK-MB assay. When used for patients in whom a cardiac care unit admission is not considered, the rapid assay may identify some patients with unsuspected myocardial infarction and prevent inadvertent discharge or admission to unmonitored beds.

Adult↗
PubMed1990

Sex knowledge, attitudes, and experience of Chinese medical students in Hong Kong.

Sex knowledge, attitudes, and experience of 83 Chinese undergraduate medical students were assessed in their responses to the Sex Knowledge and Attitude Test. They were found to be relatively less knowledgeable especially in areas of social and cultural data-based knowledge and were less liberal especially in attitudes toward heterosexual relations and abortion. While increased knowledge tended to be associated with the repudiation of sexual myths, a general conservative outlook as assessed by the Wilson-Patterson Conservatism Scale was found to have the greatest influence on attitudes toward heterosexual relations, autoeroticism, and abortion. In contrast to the sexual practice of young Chinese of similar age based on another survey, the present sample of medical students was relatively heterosexually inexperienced. Implications for medical education with value reorientation are discussed.

Adaptation, Psychological↗
PubMed1990

The Maudsley Obsessional-Compulsive Inventory: a psychometric investigation on Chinese normal subjects.

The 30-item Maudsley Obsessional-Compulsive Inventory (MOCI) was administered to 183 normal English-speaking Chinese subjects. The inventory achieved modest to relatively low internal consistency as a scale and as four subscales. Three independent dimensions of obsessional complaints interpretable as Perfectionistic and Repetitive Checking, Fear of Contamination, and Doubting Rumination emerged in the factor analysis of item responses. While the first factor corresponded to the Checking component, the second to the Cleaning component, the third was reminiscent of the Doubting, Ruminating and Slowness components. The responses to the MOCI were also explored in their correlations with depression and assertiveness. These results were discussed in in terms of the development of a refined and shortened version of the MOCI and their implications for developing differential treatment models for obsessive-compulsive patients.

Adolescent↗
PubMed1990

The relationship of prostate specific antigen levels and residual tumor volume in stage A prostate cancer.

Preoperative serum prostate specific antigen correlates well with morphometrically determined prostate tumor volume in prostatectomy specimens. However, since prostate specific antigen is produced by hyperplastic as well as malignant prostatic epithelium, the contribution of hyperplastic epithelium (benign prostatic hyperplasia) to serum prostate specific antigen interferes with the ability of serum prostate specific antigen to predict tumor volume in individual patients. We wondered if the removal of benign prostatic hyperplasia tissue would increase the correlation between prostate specific antigen and tumor volume, and, thus, make prostate specific antigen a more accurate predictor of residual cancer volume after transurethral resection of the prostate. A total of 67 patients with clinical stage A cancer underwent radical retropubic prostatectomy (22, or 33%, with stage A1 and 45, or 67%, with stage A2 disease), and had pre-radical prostatectomy measurement of serum prostate specific antigen and morphometric determination of residual cancer volume in the radical prostatectomy specimen. The correlation between serum prostate specific antigen and residual cancer volume for all 67 patients was 0.66, and for stages A1 and A2 disease it was 0.64 and 0.70, respectively. All stage A1 cancer patients with a serum prostate specific antigen value of 1 ng./ml. or less had residual tumor volumes of less than 0.5 cc and all stage A cancer patients with a serum prostate specific antigen value of more than 10 ng./ml. had residual tumor volumes of greater than 0.5 cc. Of the patients 51% had levels of 1 to 10 ng./ml. and serum prostate specific antigen was not useful to predict residual tumor volume in this group. Serum prostate specific antigen measurements may be helpful in stage A1 cancer patients with levels of 1 ng./ml. or less, or greater than 10 ng./ml. in choosing the most appropriate therapy.

Antigens, Neoplasm↗
PubMed1990

Prostate specific antigen in the staging of localized prostate cancer: influence of tumor differentiation, tumor volume and benign hyperplasia.

To evaluate the usefulness of serum prostate specific antigen in the preoperative staging of prostate cancer we examined tumor volume and differentiation, as well as benign prostatic hyperplasia volume to determine their influence on serum antigen levels. Serum prostate specific antigen was measured in 350 men with clinically localized prostate cancer and preoperatively in 72 men with documented benign prostatic hyperplasia. Although the mean antigen levels increased with advancing pathological stage, the usefulness of prostate specific antigen to predict pathological stage for an individual patient was limited: 1 of 102 men (0.9%) with prostate specific antigen levels of less than 2.8 ng./ml. had positive lymph nodes and 5 of 5 men with levels of greater than 100 ng./ml. had either seminal vesicle or lymph node involvement. However, for the majority of men (greater than 70%) with prostate specific antigen values between these 2 extremes the antigen levels did not accurately predict pathological stage. Because serum prostate specific antigen levels correlated with morphometrically determined tumor volume (r equals 0.535, p less than 0.01) they should, in fact, be predictive of pathological stage. However, most men with prostate cancer also have varying degrees of benign prostatic hyperplasia tissue in the gland producing prostate specific antigen. We have found that serum prostate specific antigen does not correlate with the volume of benign hyperplasia within the gland (r equals 0.21, p greater than 0.05). In addition, immunohistochemical studies have suggested that the lack of correlation between pathological stage and serum prostate specific antigen might be explained by a decrease in the production of antigen with increasing histological grade. Our findings of a negative correlation (r equals -0.37, p less than 0.01) between serum prostate specific antigen levels and Gleason score adjusted for tumor volume confirmed this suggestion. Consequently, serum prostate specific antigen levels do not reflect tumor burden and pathological stage accurately in individual patients for 2 reasons: 1) the unpredictable contribution from the benign prostatic hyperplasia component of the gland and 2) the decreasing production of prostate specific antigen by higher grade lesions as tumor volume increases.

Adenocarcinoma↗
PubMed1990

Psychological aspects of long-distance running among Chinese male runners in Hong Kong.

Forty-four Chinese male long-distance runners were surveyed regarding their running history, running habits, and injuries, as well as their experience of the "runner's high" phenomenon. The typical runner could be described as single, in his late 20s, well-educated, and running 60 km a week. He was also likely to be controlled and disciplined, not risk-taking, and not oriented intellectually or esthetically. While he was motivated to run to improve his physical health, he derived benefits for his emotional well-being from his running. Implications for the use of running as a therapeutic adjunct are discussed.

Adaptation, Psychological↗
PubMed1989

The influence of reversible androgen deprivation on serum prostate-specific antigen levels in men with benign prostatic hyperplasia.

This study was designed to investigate the relationship of serum prostate-specific antigen to prostatic size and hormonal stimulation. Seven patients with benign prostatic hyperplasia were treated for six months with nafarelin acetate and then followed for an additional six months. Nafarelin acetate is a potent luteinizing-hormone-releasing hormone agonist which causes reversible testosterone deprivation resulting in involution of the prostate. During therapy and follow up, serum prostate-specific antigen correlated with: 1) serum testosterone (p less than 0.001); 2) quantity of prostatic epithelium (p less than 0.001); and 3) prostatic size (p less than 0.05). Before therapy, serum prostate-specific antigen (mean +/- SD) was 0.43 +/- 0.2 ng./ml. per gram of epithelium. This did not change significantly after six months of androgen deprivation (0.48 +/- 0.36), although the ratios of prostate-specific antigen to testosterone and to prostatic size each changed significantly. Despite testosterone levels in the castrate range at six months, five of seven patients had serum prostate-specific antigen concentrations above the female range and three of seven patients had prostatic biopsies containing columnar epithelium which stained positively for prostate-specific antigen. These results demonstrate that serum prostate-specific antigen is related to prostatic size, prostatic epithelial weight, and testosterone stimulation. However, prostatic size is not a good predictor of serum prostate-specific antigen because there is tremendous variation in the relative amount of epithelium in a prostate; in this study the ratio of prostatic size to epithelial weight varied threefold. Furthermore, although testosterone determines prostatic size and amount of prostatic epithelium, it may not totally control prostate-specific antigen production.

Aged↗
PubMed1989

The value of prostate-specific antigen in the management of localized prostatic cancer.

Prostate-specific antigen has proven to be a new useful marker for the evaluation of men with prostatic cancer. In addition to its proven value for immunohistochemical staining and for the followup evaluation of men treated with hormonal therapy, the monoclonal immunoradiometric assay for PSA has proven to be a unique, sensitive, and specific marker for the followup evaluation of men who have undergone radical prostatectomy.

Adenocarcinoma↗
PubMed1988

Prostate specific antigen in the preoperative and postoperative evaluation of localized prostatic cancer treated with radical prostatectomy.

The usefulness of prostate specific antigen to predict final pathological stage was studied in 178 consecutive patients. Prostate specific antigen was determined preoperatively in all patients by a monoclonal immunoradiometric assay. All pathological specimens were examined for capsular penetration, seminal vesicle involvement and lymph node involvement. Prostate specific antigen correlated directly with capsular penetration (p less than 0.002), seminal vesicle involvement (p less than 0.02) and lymph node involvement (p less than 0.05). However the diagnostic accuracy of an elevated serum antigen level on an individual basis was only 55 per cent for capsular penetration and 50 per cent for seminal vesicle involvement and lymph node involvement. With a log-linear regression model, the half-life of prostate specific antigen was calculated to be 3.15 +/- 0.09 days. From the equation PSA (t) equals PSA (2) e[-0.2197(t-2)], prostate specific antigen can be used to detect residual cancer on day t in the immediate postoperative period. With respect to long-term followup, 127 patients have been monitored for longer than 2 months postoperatively with prostate specific antigen (mean followup 2 years, range 2 months to 8.6 years). Of the 101 patients who had favorable pathological findings at operation (organ-confined cancer or capsular penetration only) 92 (91 per cent) had a followup antigen concentration in the female range (0.0 to 0.2 ng. per ml.), whereas only 5 of 26 men (19 per cent) with either seminal vesicle involvement or lymph node involvement had an antigen value that was less than 0.2 ng. per ml. All patients with a documented clinical recurrence (8 of 127, 6 per cent) had an elevated followup serum prostate specific antigen concentration. These findings suggest that preoperative levels of prostate specific antigen are not sufficiently reliable to predict final pathological stage on an individual basis in patients with early prostatic cancer, and that the antigen is a sensitive tumor marker for the detection of residual disease after radical prostatectomy and subsequent recurrence of tumor on long-term followup.

Adenocarcinoma↗
PubMed1988

A new biomarker in monitoring breast cancer: CA 549.

Serum biomarkers are not very reliable in assessing outcome or predicting recurrence of breast cancer. Clinically, carcinoembryonic antigen (CEA) is widely used and is elevated in a majority of patients with metastatic breast cancer. However, it is falsely elevated in a wide range of nonmalignant conditions and correlates poorly with disease progression. We evaluated a newly described monoclonal antibody, CA 549, in an immunoradiometric assay which uses two monoclonal antibodies directed against tumor and milk fat globule membranes. CA 549 and CEA were studied in 682 patients, 331 of whom had breast diseases and 99 of whom were followed with multiple serum samples. Of 69 patients with benign breast diseases, 1.5% had elevated CA 549, 0% of 30 pregnant women had elevated CA 549, and 26% of patients with nonmalignant liver disease had CA 549 elevation. In metastatic cancer of prostate, ovary, endometrium, colon, and lung CA 549 was elevated in 12% to 50% of cases with levels less than 120 U/mL. In breast cancer, CA 549 was elevated in 11% of 88 patients who received adjuvant chemotherapy and had no evidence of metastasis; in 23% of 16 patients in complete remission after chemotherapy; in 63% of 52 patients in partial remission after therapy; and in 83% of 106 patients with progression of breast cancer compared with 63% with elevated CEA (P = .001). In diseases of the breast, CA 549 has a sensitivity In diseases of the breast, CA 549 has a sensitivity and specificity of 77% and 92% v 61% and 92% for CEA. Of 99 patients serially monitored with clinically documented breast cancer progression, regression, or stability of disease, CA 549 was statistically significantly superior to CEA in monitoring a greater than 25% change in those patients with metastatic progression (P = .03). CA 549 is a new serum marker that should be control tested in prospective clinical trials alone or in conjunction with other markers.

Adenocarcinoma↗
PubMed1988

Monitoring hepatocellular carcinoma by using a monoclonal immunoenzymometric assay for alpha-fetoprotein.

A monoclonal immunoenzymometric assay for alpha-fetoprotein (M-AFP) was evaluated with respect to its utility in monitoring hepatocellular carcinoma (HCC) patients. Earlier (Clin Chem 1986;32:1318-22), we found this immunoassay to demonstrate abilities similar to polyclonal AFP assays, and we suggested that changes in M-AFP correlated with changes in intrahepatic tumor volume in most HCC patients. In the present study, 107 HCC patients were evaluated between 1978 and 1986. Patient demographics characterized this study population as being similar to those seen in regions with low incidence of HCC. Changes in serum M-AFP concentration correlated moderately (r = 0.55) with changes in intrahepatic tumor volume. The AFP concentration in serum was found to be a statistically significant independent predictor of survival; patients with above-normal M-AFP (AFP[+]) at presentation demonstrated a median survival time of 10 months, compared with 16 months for patients with "normal" values for M-AFP (AFP[-]) (P = 0.008). This prognostic pattern persisted when adjusted for serum bilirubin concentration (AFP[+] 12 months vs AFP[-] 29 months, P = 0.01).

Adolescent↗
PubMed1988

Monitoring breast cancer with CA 549.

CA 549, a new marker for breast cancer, was measured in serum of 719 patients by an immunoradiometric assay involving two monoclonal antibodies: BC4E 549, developed against a breast-tumor cell line, and BC4N 154, developed against milk fat-globule membrane. The reference interval for healthy women was 0-11 kilo-units/L. The percentages of patients with CA 549 greater than 11 kilo-units/L for benign conditions are: 0% pregnancy, 1% breast, 26% liver; and for nonbreast metastatic cancers: 12% endometrial, 33% lung, 40% prostatic, and 50% ovarian. In women with breast cancer who were receiving or had completed adjuvant therapy with no evidence of disease there was an 11% increase in CA 549. For patients with metastatic breast cancer, 19% of those in complete remission, 63% of those in partial remission, and 88% of those with systemic progression had increased CA 549. CA 549 is a more specific marker than carcinoembryonic antigen (CEA) in nonmalignant disease, nonbreast malignancies, and adjuvant breast-cancer patients, and it is more sensitive in breast-cancer patients with progressive disease than is CEA. We could show CA 549 to be superior to CEA for detecting active breast cancer in patients with malignant or nonmalignant breast diseases. In monitoring 19 adjuvant-treated patients, CA 549 correlated more closely with the clinical course than did CEA values and, when increased, predicted a clinical recurrence. In 18 breast-cancer patients with metastasis, monitored for two to three years, the change of CA 549 values paralleled disease courses more often than did CEA values.

Adult↗
PubMed1987

Prostate-specific antigen as a marker for prostatic cancer: a monoclonal and a polyclonal immunoassay compared.

We evaluated the clinical utility of prostate-specific antigen (PSA) in diagnosis and management of prostatic cancer, using a monoclonal immunoradiometric assay (M-PSA) and a polyclonal radioimmunoassay (P-PSA). Assay CVs ranged from 1.3% to 4.9% (M-PSA) and from 5.1% to 8.0% (P-PSA). Detection limits were 0.1 microgram/L (M-PSA) and 0.2 microgram/L (P-PSA). Reference intervals established for healthy men were: 0-2.8 micrograms/L (M-PSA) and 0-4.2 micrograms/L (P-PSA). The regression equation for the PSA concentrations (0-100 micrograms/L) measured in normal men, men with primary prostatic cancer, and men with benign prostatic hypertrophy (BPH) was: P-PSA = 1.603 M-PSA - 0.120 microgram/L (r = 0.9923, n = 201). The P-PSA calibrators yielded one-half their assigned values when analyzed by the M-PSA assay. With either assay there were proportional increases in PSA values with advancing cancer. The proportion of PSA values exceeding the reference interval was 50% for patients with stage A prostatic cancer, 80% (stage B), 100% (stages C and D), and 65% for men with BPH. After radical prostatectomy, the follow-up PSA values for most patients were within the reference intervals for women (0-0.2 microgram/L for M-PSA, 0-0.8 microgram/L for P-PSA). Most patients with above-normal PSA values have clinically detectable disease.

Antibodies↗
PubMed1987

Evaluation of a monoclonal immunoradiometric assay for prostate-specific antigen.

We evaluated the analytical performance of a new monoclonal immunoradiometric assay ("M-PSA") for prostate-specific antigen ("Tandem"; Hybritech Inc.) in comparison with a monoclonal immunoradiometric assay ("M-PAP") for mass measurement of prostatic acid phosphatase ("Tandem") and with a conventional enzyme-activity assay ("E-PAP") for prostatic acid phosphatase (EC 3.1.3.2). For M-PSA, the CVs were 1.3-3.0% within-run and 3.0-4.9% between-run. The minimum detectable mass concentration was 0.10 microgram/L, and linearity extended to 100 micrograms/L. The reference interval for M-PSA in 178 healthy men was 0-2.8 micrograms/L. Serum specimens from men with prostatic disease (primarily prostatic carcinoma and benign prostatic hypertrophy) were assayed by the three methods. Correlation was best between mass measurement (M-PAP) and enzyme activity (E-PAP) for prostatic acid phosphatase (r = 0.958). Results for PSA did not correlate well with those for either M-PAP (r = 0.629) or E-PAP (r = 0.387). PSA was increased in a higher percentage of specimens from men with earlier (clinical stage B) prostatic carcinoma than were results from either assay for PAP.

Acid Phosphatase↗