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Biomedical subjects

Y M Chan

Publications and source records attributed to Y M Chan.

At least 37 records · Page 2Linked to original sources
PubMed2000

Solidification and stabilization of asbestos waste from an automobile brake manufacturing facility using cement.

Currently, the generated brake lining waste dust, which contains asbestos as its major component, is disposed of into a secure landfill without any additional treatment. As an alternative to this, solidification/stabilization (S/S) disposal of the dust was investigated using Portland cement alone and Portland cement mixed with activated carbon (AC), as the binders. Toxicity Characteristics Leaching Procedure (TCLP) results on the solidified matrix showed that cement was able to immobilize the heavy metals, Ba, Zn, Cr, Pb, Cu and Fe, to within the limits set by the US EPA for TCLP. Addition of AC to the cement reduced the leaching of heavy metals by an additional 4-24% compared to cement alone. The pH of the TCLP leachate extracted from virgin cement, and from dust treated with cement with or without AC was found to increase to 10.9-12.5 as opposed to an initial value of 4.93 for the TCLP extract for the untreated dust. Results of ANS 16.1 (modified) leach protocol revealed that Ba in cement-treated samples showed the highest leach rate, followed by Zn, Pb, Cr, Cu and Fe. The leach rate of heavy metals decreased with progress in time. Cement mixed with AC exhibited similar leach characteristics, however, the leach rate was lower. The linear relationship between the cumulative fraction leached (CFL) and the square root of leaching time in all cement-based samples indicate that a diffusional process is the controlling transport mechanism for the leaching of the heavy metals. The obtained Leachability Indices (L(i)) of 7.6-9.1 and 8.3-9.5 for cement and cement with AC, respectively, were low but exceeded the guidance value of 6, which clearly indicates that all the heavy metals studied are retained well within solid matrices. Cement-based S/S hardening times increased from 30 to 96 h as the dust content increased from 40 to 70 wt.%. The resulting solid matrices exhibited a compressive strength ranging from 1 to 12 MPa, which was well above the specified limit of 414 kPa for such matrices. An economic analysis indicates that the disposal costs for the dust in the only available secure landfill would increase by 40.3% if one were to go for the cement S/S option. Addition of AC to the cement would escalate this by an additional 43.8%. Although the S/S of brake lining dust using cement effectively immobilized the heavy metals of concern, cost considerations may hinder the commercial adaptation of this technique for waste disposal unless new regulatory demands are implemented.

Asbestos↗
PubMed2000

Filamin 2 (FLN2): A muscle-specific sarcoglycan interacting protein.

Mutations in genes encoding for the sarcoglycans, a subset of proteins within the dystrophin-glycoprotein complex, produce a limb-girdle muscular dystrophy phenotype; however, the precise role of this group of proteins in the skeletal muscle is not known. To understand the role of the sarcoglycan complex, we looked for sarcoglycan interacting proteins with the hope of finding novel members of the dystrophin-glycoprotein complex. Using the yeast two-hybrid method, we have identified a skeletal muscle-specific form of filamin, which we term filamin 2 (FLN2), as a gamma- and delta-sarcoglycan interacting protein. In addition, we demonstrate that FLN2 protein localization in limb-girdle muscular dystrophy and Duchenne muscular dystrophy patients and mice is altered when compared with unaffected individuals. Previous studies of filamin family members have determined that these proteins are involved in actin reorganization and signal transduction cascades associated with cell migration, adhesion, differentiation, force transduction, and survival. Specifically, filamin proteins have been found essential in maintaining membrane integrity during force application. The finding that FLN2 interacts with the sarcoglycans introduces new implications for the pathogenesis of muscular dystrophy.

Amino Acid Sequence↗
PubMed2000

Female urethral adenocarcinoma arising from urethritis glandularis.

INTRODUCTION: Female urethral adenocarcinoma is extremely rare and more than one tissue of origin has been suggested other than the Skene's gland. Immunohistochemistry with cytokeratins (CK) 7 and 20 is used to define the origin of the tumor. CASE REPORT: A 72-year-old woman presented with a 2-cm polypoid tumor at the external urethral meatus and bleeding. Wide local excision and bilateral inguinal lymphadenectomy were performed. Postoperative convalescence was uneventful. It was a poorly differentiated mucinous adenocarcinoma without direct urothelial involvement. There were focal areas of intestinal metaplasia. The tumor cells were positive for CK 7 and 20 and negative for prostate-specific antigen. DISCUSSION: This case provides supportive evidence that mucinous urethral adenocarcinoma may arise from malignant transformation of urethritis glandularis.

Adenocarcinoma↗
PubMed2000

Malignancy of the temporal bone and external auditory canal.

A retrospective study of 18 patients with malignant tumors of the external auditory canal and temporal bone was undertaken to gain an Asian perspective of this rare disease. Of these patients, 15 (83%) had squamous cell carcinoma (SCC) and 61% had stage T3 tumors at presentation. The mean age was 56 years (range 38-82 years). Seven (39%) of the 18 patients had radiation-associated tumors (RATs), and all had undergone radiotherapy for treatment of nasopharyngeal carcinoma. The 1-year cumulative recurrence for the RAT group was 100%, but there was no recurrence in the non-RAT group (P = 0.001). In malignancies of the external auditory canal and temporal bone, a different classification and staging system for patients with RATs may be warranted to better guide treatment strategies.

Adult↗
PubMed2000

Could the incidence of postoperative urinary tract infection be reduced by reversing the sequence of vaginal cleansing and urethral catheterization?

Postoperative urinary tract infection (UTI) is a common hospital infection after gynaecological operations. A prospective randomized study was performed to examine whether the incidence of UTI could be reduced by reversing the sequence of vaginal cleansing and urethral catheterization. Subjects were randomly allocated to: (1) urethral catheterization before vaginal cleansing; and (2) urethral catheterization after vaginal cleansing. Urine cultures were performed immediately after the procedures as the baseline, on the day of catheter removal, and two days after catheter removal. Patients were examined daily after the operation for any urinary symptoms and fever. The incidences of preoperative asymptomatic bacteriuria were similar in both groups, seven of 84 in group 1 vs. eight of 83 in group 2. Among those with negative urine culture before the operation, 77 in group 1 and 75 in group 2, there was no significant difference in postoperative bacteriuria at catheter removal (23 vs. 22) and two days later (35 vs. 42). No significant difference was noted in the incidence of UTI (5 vs. 10, P = 0.25), with a trend towards less UTI in group 1. Voiding discomfort was more common, and fever less common in group 1. There were significant associations between urine culture results at three different occasions. Bacteriuria at catheter removal is associated with a 7.2 times risk of bacteriuria two days later, 2.4 times risk of urinary symptoms and 3.2 times risk of UTI. Routine surveillance at catheter removal is not cost-effective. We conclude that postoperative bacteriuria and UTI are common. Reversing the sequence of the procedures cannot reduce the incidence. There is no evidence to change the status quo.

Bacteriuria↗
PubMed2000

A gain-of-function screen for genes that affect the development of the Drosophila adult external sensory organ.

The Drosophila adult external sensory organ, comprising a neuron and its support cells, is derived from a single precursor cell via several asymmetric cell divisions. To identify molecules involved in sensory organ development, we conducted a tissue-specific gain-of-function screen. We screened 2293 independent P-element lines established by P. Rorth and identified 105 lines, carrying insertions at 78 distinct loci, that produced misexpression phenotypes with changes in number, fate, or morphology of cells of the adult external sensory organ. On the basis of the gain-of-function phenotypes of both internal and external support cells, we subdivided the candidate lines into three classes. The first class (52 lines, 40 loci) exhibits partial or complete loss of adult external sensory organs. The second class (38 lines, 28 loci) is associated with increased numbers of entire adult external sensory organs or subsets of sensory organ cells. The third class (15 lines, 10 loci) results in potential cell fate transformations. Genetic and molecular characterization of these candidate lines reveals that some loci identified in this screen correspond to genes known to function in the formation of the peripheral nervous system, such as big brain, extra macrochaetae, and numb. Also emerging from the screen are a large group of previously uncharacterized genes and several known genes that have not yet been implicated in the development of the peripheral nervous system.

Animals↗
PubMed2000

Vaginal misoprostol alone for medical abortion up to 9 weeks of gestation: efficacy and acceptability.

Misoprostol and mifepristone have been shown to be effective for medical abortion up to 9 weeks of gestation. When used alone, the successful complete abortion rate dropped to approximately 60%. It has been demonstrated that by adding water to misoprostol, the success rate rose to 92%. This is the first randomized study to investigate the efficacy of misoprostol and water versus misoprostol alone for first trimester medical abortion in women at </= 9 weeks of gestation. Eighty women were randomly assigned to group 1 (water added to misoprostol) and group 2 (misoprostol alone). Vaginal misoprostol 800 microgram was given on days 1, 3 and 5. If the woman did not require vacuum aspiration during the period up to the return of first menstruation after medical abortion, the outcome was classified as complete abortion. The incidence of side-effects and the acceptability were assessed through a standardized questionnaire during and after the abortion. The complete abortion rate appeared higher when water was added but the difference did not reach statistical significance. Gastro-intestinal side-effects were common but well tolerated in both groups. Overall, 40% of the women preferred a surgical method in the future because of the high failure rate. With an overall complete abortion rate of 85%, it is probably not a clinically acceptable method even if the addition of water can improve the results. We conclude that the addition of water onto misoprostol tablets does not improve its efficacy in first trimester medical abortion. Misoprostol alone is not recommended for medical abortion (up to 9 weeks of pregnancy) because of the high failure rate and low acceptability.

Abortifacient Agents, Nonsteroidal↗
PubMed2000

Labour characteristics and uterine activity: misoprostol compared with oxytocin in women at term with prelabour rupture of the membranes.

OBJECTIVE: To compare the labour pattern and uterine activity of oral misoprostol with oxytocin for labour induction in women presenting with prelabour rupture of membranes at term. DESIGN: Prospective randomised study. SETTING: Department of Obstetrics and Gynaecology, Queen Mary Hospital, Hong Kong. PARTICIPANTS: Eighty women presenting with prelabour rupture of membranes at term. METHODS: The women were randomised to receive either 100 microg misoprostol orally every 4 hours to a maximum of three doses, or intravenous oxytocin infusion according to the hospital protocol. Intrauterine pressure transducers were inserted one hour before induction of labour in both groups of women. We compared the pattern of uterine activity, the induction-to-delivery interval, duration of labour, mode of delivery and neonatal outcome between the two groups. RESULTS: Both oxytocin and oral misoprostol caused an increase in uterine activity within one hour of labour induction. Peak uterine activity was reached 6-8 h after oral misoprostol, with persistent effects, and 8-10 h after oxytocin, requiring continuous titration of medication. The duration of labour was significantly reduced in nulliparous women, but not in those who were multiparous in the misoprostol group. The induction-to-delivery interval, the mode of delivery and the perinatal outcome were similar for the two groups. CONCLUSION: Oral misoprostol caused earlier peak uterine activity, compared with oxytocin (6-8 h vs 8-10 h). Oral misoprostol was not only as effective as oxytocin in inducing labour in women at term with prelabour rupture of the membranes, but it reduced significantly the duration of labour in nulliparous women.

Administration, Oral↗
PubMed2000

Effect of pre-incision skin infiltration on post-hysterectomy pain--a double-blind randomized controlled trial.

In this double-blind placebo-controlled randomized trial, we compared the analgesic effect of preoperative 0.25% bupivacaine (n = 21) skin infiltration with normal saline (n = 19) in patients undergoing abdominal hysterectomy through a lower midline incision. All patients received postoperative patient-controlled analgesia with morphine and were followed for 72 hours. The main outcome measures were morphine consumption and pain score at rest, and the contribution of different components of pain was also assessed prospectively. No statistically significant differences were found. All except one patient (n = 39) could distinguish the different characteristics of somatic and visceral pain. Visceral pain predominated in the first 48 hours. We concluded that local anaesthetic infiltration is not effective in reducing pain after abdominal hysterectomy. Effective postoperative analgesia should aim to eliminate the visceral pain component.

Analgesia, Patient-Controlled↗
PubMed2000

Aggressive angiomyxoma in females: is radical resection the only option?

BACKGROUND: Aggressive angiomyxoma is a rare mesenchymal tumor, characterized by frequent local recurrences. Our aim is to assess the role of radical resection. METHODS: Retrospective case review. The records of five patients with aggressive angiomyxoma during the period from 1984 to 1998 were reviewed and analyzed. A MEDLINE search from 1983 to May 1999 was performed. The clinical presentation, surgical treatment, resection margin involvement and clinical outcomes were analyzed. RESULTS: Together with our five cases, 106 cases have been reported in the world literature. The female-to-male ratio was 6.6:1. The age distribution was wide, with the peak incidence at 31 to 35. The local recurrence rate was high. Seventy-one percent of recurrence occurred within the first 3 years. Patients with clear resection margins have similar chances of remaining disease-free compared with those having tumor-involved resection margins. There was no correlation between the size of the tumors and the chance of recurrence. CONCLUSIONS: Though we aim for complete resection, incomplete or partial resection is acceptable, especially when high operative morbidity is anticipated and preservation of fertility is an issue. Long-term follow-up and careful monitoring with imaging techniques are essential for timely identification of recurrence and prompt resection.

Adolescent↗
PubMed1999

Pathology slide review in gynecologic oncology: routine or selective?

OBJECTIVE: The aims of this study were to assess the cost/benefit ratio for interinstitution pathology consultation (IPC) and to identify the types of specimens with little or no risk of diagnostic error in order to reduce the cost. METHODS: All gynecologic oncology referrals having IPC from 1993 to 1998 were reviewed. Each case was evaluated by comparing both the original and the consulted pathology reports. A discrepancy was major if it led to treatment alteration. A minor discrepancy was defined as differences without clinical consequences. Consultation error was determined by comparison with the final diagnosis and clinical data obtained from the records. The cost per review was adjusted to 1998 dollars for all cases over the 5-year study period. Statistical data were obtained by Fisher's exact test and Pearson's correlation test. RESULTS: Five hundred sixty-nine pathology specimens from 498 patients were analyzed in this study. The major discrepancy rate was 6.5% and the minor discrepancy rate was 12.5%. Cytological specimens accounted for no major discrepancy and 13 minor discrepancies compared to 37 major and 58 minor discrepancies in histological specimens. The difference was statistically significant (P = 0.003). Consultation errors occurred in 5 cases with no alteration of clinical care. By excluding cervical and vaginal smears and cervical biopsy specimens in cases with clinically gross tumors, the cost can be reduced by 25% with no detriment to the clinical management. CONCLUSIONS: The types of specimens that do not need consultative pathology review include (1) cervical biopsy specimens in those patients with gross tumors and (2) cervical and vaginal smears.

Biopsy↗
PubMed1999

Accelerated evolution and molecular surface of venom phospholipase A2 enzymes.

Multiple phospholipase A2 (PLA2) isoenzymes found in a single snake venom induce a variety of pharmacological effects. These multiple forms are formed by gene duplication and accelerated evolution of exons. We examined the amino acid sequences of 127 snake venom PLA2 enzymes and their homologues to study in which location most natural substitutions occur. Our data show that hot spots of amino acid substitutions in this group of proteins occur mostly on the surface. A logistic model correlating the substitution rates of each amino acid residue with their surface accessibility indicates that the probability of natural substitutions occurring in the fully exposed residue is 2.6-3.5 times greater than that of substitutions occurring in buried residues. These surface substitutions play a significant role in the evolution of new PLA2 isoenzymes by altering the specificity of targeting to various tissues or cells, resulting in distinct pharmacological effects. Thus natural substitutions in PLA2 enzymes, in contrast to popular belief, are not random substitutions but appear to be directed toward modifying the molecular surface.

Amino Acid Sequence↗
PubMed1999

Conservation of neurogenic genes and mechanisms.

Reports from the past year have demonstrated that neural basic helix-loop-helix genes and LIM homeobox genes contribute to neuronal subtype specification in vertebrates and invertebrates, that Notch signaling specifies cell fates in the developing vertebrate inner ear, and that the organization of the central nervous system into three columns is shared by vertebrates and invertebrates. These findings pave the way for future work that will help to establish the extent to which these similarities represent evolutionary conservation.

Animals↗
PubMed1999

The relationship between diabetes knowledge and compliance among Chinese with non-insulin dependent diabetes mellitus in Hong Kong.

This study examines the relationship between diabetes knowledge and compliance among Chinese with non-insulin dependent diabetes mellitus (NIDDM) in Hong Kong. A cross-sectional design was used to collect data through structured self-report interviews based on validated scales assessing diabetes knowledge, compliance behaviours and demographic data. The Diabetes Knowledge Scale was used to sample knowledge in the major areas of basic physiology of diabetes and general principles of diabetes care. Compliance level was assessed by using the Compliance Behaviour Questionnaire, inspection of patients' feet and the value of HbA1c. A convenience sample of 52 Chinese with NIDDM receiving out-patient diabetes care participated in the study on a voluntary basis. Descriptive and correlational statistical analyses were used to analyse the data. The findings indicated that there was no association between diabetes knowledge and compliance. There was a gap between what the patients were taught and what they were actually doing. Most of the patients gained higher marks on factual knowledge on diabetes but lost marks on the application of knowledge to their real life situations. Strategies are suggested to close the 'knowledge-action gap' and increase patients' motivation and ability to comply with the health regimen.

Adult↗
PubMed1999

The use of misoprostol for pre-operative cervical dilatation prior to vacuum aspiration: a randomized trial.

Misoprostol is effective for cervical priming prior to vacuum aspiration for first trimester termination of pregnancy. Previous studies showed that the oral route was more acceptable to patients but there were higher incidences of side-effects when compared with the vaginal route. This study is to determine the optimal dosage and route of administration of misoprostol for pre-operative cervical dilatation. A double-blind, randomized trial was undertaken for 225 nulliparous women with 8-12 weeks amenorrhoea. They were randomly assigned to groups given 0 (placebo), 200 or 400 microg oral or vaginal misoprostol 3 h prior to vacuum aspiration. In misoprostol-treated groups the baseline cervical dilatation was significantly increased when compared with the placebo group; the effect was dose-related in the oral but not in the vaginal group. The cumulative force and blood loss was significantly decreased in the misoprostol-treated groups. The incidences of side-effects were more frequent in misoprostol groups but were not related to the route and dosage of medication. The duration of procedure, incidences of post-operative complications, the duration of post-operative bleeding and the interval to the first period were similar in the five treatment groups. We conclude that a 3 h pre-treatment interval is effective for both oral and vaginal routes. When given orally, 400 microg is more effective than 200 microg. The efficacy was otherwise similar when compared with the vaginal route. We recommend 400 microg oral misoprostol 3 h prior to vacuum aspiration for cervical dilatation.

Abortifacient Agents, Nonsteroidal↗
PubMed1999

Mitomycin chemotherapeutic pleurodesis to palliate malignant pleural effusions secondary to gynecological cancer.

BACKGROUND: To assess the efficacy of mitomycin pleurodesis in women with end stage malignant effusion. METHODS: Retrospective analysis. RESULTS: Of the 13 patients treated six had ovarian, six had endometrial and one had cervical adenocarcinoma. The median time of onset of effusion from diagnosis of primary disease was 12 months (range 1-75). Ten patients were evaluable for response. The median age of the patients was 59 years (range 42 to 74). Ten (77%) of them had repeated thoracocentesis prior to mitomycin pleurodesis. The median duration and volume of drainage was 4 days (range 2-11) and 3.1 liters (range 1.2-10.2) respectively. One of two patients developed a pneumothorax and required the insertion of an additional chest drain. Overall, seven patients (70%) responded - one completely (CR) and six partially (PR), while three did not respond. Four of five patients with ovarian cancer had a partial response, two of four patients with endometrial cancer (one CR and one PR) responded. The only patient with cervical cancer had a partial response. Nine patients (69%) had enough symptomatic improvement to be discharged home. The drug cost of bleomycin 60 units (US$191), another commonly used agent, was more than twice as expensive as mitomycin 30 mg (US$84). CONCLUSIONS: Mitomycin pleurodesis can palliate 70% of patients for at least 1 month. It offers cheap and effective palliation. There is a suggestion that patients' quality of life is improved.

Adult↗
PubMed1999

Colon cancer in pregnancy. A case report.

BACKGROUND: Carcinoma of the colon diagnosed during pregnancy is very rare. Delayed diagnosis is common because of the similarity between early signs and symptoms of colon cancer and gastrointestinal complaints often experienced by pregnant women. We report a case of early-stage colon cancer in pregnancy with a good outcome. CASE: A 35-year-old woman presented with rectal bleeding at 26 weeks of gestation. Initial assessment with digital examination and proctoscopy revealed only a mild degree of hemorrhoids. Colonoscopy and biopsy at 30 weeks of gestation showed sigmoid colon cancer. Cesarean section was performed after steroid therapy. Subtotal colectomy and ileosigmoid anastomosis were then performed at the same setting. Postoperative adjuvant chemotherapy was given. There was no evidence of recurrence at this writing, 28 months after surgery. CONCLUSION: Colon cancer is a rare complication of pregnancy. The associated poor prognosis is usually due to delay in diagnosis. A high index of suspicion is essential, and it is important not to underestimate the patient's symptoms. Early diagnosis is the key to longer survival.

Adult↗