Biomedical subjects

H T Ng

Publications and source records attributed to H T Ng.

At least 19 recordsLinked to original sources

PubMed2005

Silicon nanowire synthesis by a vapor-liquid-solid approach.

Synthesis of silicon nanowires is studied by using a vapor-liquid-solid growth technique. Silicon tetrachloride reduction with hydrogen in the gas phase is used with gold serving as catalyst to facilitate growth. Only a narrow set of conditions of SiCl4 concentration and temperature yield straight nanowires. High concentrations and temperatures generally result in particulates, catalyst coverage and deactivation, and coatinglike materials.

Crystallization↗

PubMed2005

Radical hysterectomy: past, present, and future.

After an analysis of 3,441 radical hysterectomies performed in our department, we found, after modification of the operative technique in 1983, the more lateral the excision the less the recurrence rate. The recurrence rate for Stage 1b-2a and Stage 2b patients comparing the years before 1983 to the years after decreased to 12.4% from 15.7% (158/1,006 vs 268/2,163; p = 0.009) in Stage 1b-2a and 24.6% from 55.8% (38/68 vs 47/191; p = 0.0007) in Stage 2b, respectively. With the modern trend of aspiring for an easier lifestyle, most physicians practice earlier. Therefore only very few physicians study radical hysterectomy. As the skill of surgery needs a longer period of education and training, it may only interest physicians who work with medical professionals as part of a team at a medical center. In the future, we should provide gynecological residents not only with a training program using the classic textbooks, but also with different points of view on changes and developments in radical hysterectomy. We hope to promote an attitude of offering patients access to different choices and opportunities of therapy. Radical hysterectomy is in fact a treatment option for patients with bulky cervical lesions and Stage 2b in particular.

Female↗

PubMed2003

The assessment of stability and reliability of a virtual reality-based laparoscopic gynecology simulation system.

PURPOSE OF INVESTIGATION: Surgeons require practiced skills in laparoscopic surgery. A virtual reality-based simulator system was developed for extensive training. The purpose of this study was to assess the feasibility of a virtual reality-based laparoscopic gynecology simulation system. METHODS: Laparoscopic tools and three-dimensional virtual environments were included in the simulation system. Ten healthy, non-disabled volunteers were recruited. The surgical procedure is a process of tubal sterilization by cauterization. Volunteers followed the training procedure, 15 trials in the first test and retest, respectively. RESULTS: Stable performances were obtained after about seven trials for all subjects. The intraclass correlation coefficients were 0.935 and 0.425 for task time and error frequency, respectively. CONCLUSION: The results of this study indicate that the system is stable and has a fair high test-retest reliability. Therefore, the VR-based laparoscopic gynecology system is feasible.

Adult↗

PubMed2002

Both TPA and SCC-Ag levels are prognostic even in high-risk stage Ib-IIa cervical carcinoma as determined by a stratification analysis.

OBJECTIVE: To determine the prognostic values of tissue polypeptide antigen (TPA), squamous cell carcinoma antigen (SCC-Ag), and carcinoembryonic antigen (CEA) in the sera of cervical carcinoma patients, especially in those with a poor prognosis. METHODS: In this retrospective study, the preoperative serum SCC-Ag, TPA, and CEA were analyzed in 779 patients with cervical squamous cell carcinoma of stage Ib-IIa who received radical hysterectomy and pelvic lymph node dissection (RAH-PLND) between 1984 and 1994. RESULTS: Due to poor predictive value and poor correlation between serum CEA and clinico-pathological factors, CEA was abandoned in this study. Elevated TPA and SCC-Ag levels, pelvic lymph node metastasis (PLNM), lymphvascular space involvement (LVSI) and deep stromal invasion (DSI) were associated with poor survival time by univariate analysis. The correlation study showed that elevated serum TPA was significantly related to PLNM, LVSI, and DSI (p = 0.004, 0.008, and 0.021, respectively), and SCC-Ag was related to PLNM and bulky tumor size (p = 0.001 and 0.02, respectively). In the multivariate analysis, only PLNM and LVSI remained independently significant indicating poor survival. Further stratification studies by PLNM and LVSI showed that elevated TPA levels could even indicate higher recurrence rates in patients with PLNM (p = 0.045), as well as SCC-Ag in patients with LVSI (p = 0.038). CONCLUSIONS: The results suggest that both elevated TPA and SCC-Ag levels depicting poor prognosis in stage Ib-IIa cervical SCC, especially indicates a group of high-risk patients who may need more aggressive therapy.

Adult↗

PubMed2002

Radioimmunodetection of cervical carcinoma xenografts with (111)In-labeled MAb Cx-99 detected by a hand-held gamma detector.

PURPOSE: To establish a radioimmunodetection (RAID) system for localization of cervical cancer by labeling 111-indium ((111)In) to a monoclonal antibody against cytokeratin 19 (MAb Cx-99), and detecting it with a hand-held gamma detector in an animal model. METHODS: MAb Cx-99 was labeled with 111-Indium by the DTPA chelating method. From the second day to the seventh day after injection of this immunoconjugate into athymic nude mice bearing cervical cancer cell line CC7T xenografts, the biodistribution ratios of tumor and non-tumor radioactivity were detected by a hand-held gamma detector. Data were also correlated with the data detected by the conventional gamma counter. RESULTS: The labeling efficiency of this (111)In-labeled MAb Cx-99 and (111)In-labeled MOPC was 91.6% and 95.5%, respectively. After injection, the liver, kidney and lung were initially noticed to have high radioactivity, but the localization of tumor/tissue ratios increased progressively as time passed, indicating the effect of delayed detection for distinguishing tumor from non-tumor tissues. Except for the spleen, the range of tumor/tissue ratios was 1.18-32.7 and 1.14-39.35 for the fourth day and the seventh day, respectively. The tumor/spleen ratio remained low until the seventh day after injection, thus indicating that the spleen might have a different excretion rate. CONCLUSION: This study indicated the feasibility of a hand-held detection system in the localization of cervical cancer after injection of (111)In-labeled MAb Cx-99. The effect of delayed detection was obvious by the decreasing high bindings in the liver, spleen and kidney, with the applicable detection time being four to seven days after injection.

Animals↗

PubMed2002

Sialyltransferase family members and cervix squamous cell carcinoma.

Sialic acids including a number of their derivatives are ubiquitous at the terminal positions of the oligosaccharides of glycoproteins. The transfer of sialic acids from cystidine-5-monophospho-N-acetylneuraminic acid (CMP-NeuAc) to the terminal position of the carbohydrate group of glycoproteins and glycolipids is catalyzed by a family of sialyltransferases (STs). There is a large body of evidence to suggest that tumor cells have altered surface properties from their normal counterparts, and that these changes are partially due to altered sialo-glycoconjugates expressed on the plasma membrane and that altered sialylation (change in glycoprotein expression), which occurs during certain pathological processes, such as oncogenic transformation, tumor metastases, and invasion, is associated with enhanced ST activity. In this report we attempt to review the important findings in studing sialyltransferases of cervix squamous cell carcinoma.

Carcinoma, Squamous Cell↗

PubMed2001

Diagnosis and localization of testosterone-producing ovarian tumors: imaging or biochemical evaluation.

OBJECTIVE: In the testosterone-secreting ovarian tumor (TSOT), the role of whole-body positron emission tomography (WBPET) with (fluorine-18)-2-deoxyglucose scanning (FDG) and/or [(11)C]acetate is unclear, although it presents a rationale that these functional tumors would be more active and have increased use of glucose and oxygen consumption than normal tissues. CASE: A 52-year-old woman had a history of steroid cell tumors of the right ovary (IIA) and she received staging surgery including total hysterectomy, salpingo-oophorectomy, and lymph node sampling. Reelevated serum levels of T (5.24 ng/ml) were noted 52 months later. The patient received serial preoperative examinations including WBPET with FDG and acetate, ultrasound, computerized tomography (CT), and magnetic resonance imaging (MRI) to evaluate her recurrence. A suspicious mass on the liver was found on ultrasound, CT, and MRI. The ultrasound-guided biopsy was performed three times, and each of them failed to provide any pathological confirmation. Functional imaging studies showed an abnormal uptake in WBPET using [(11)C]acetate but were negative using FDG. Because of the size of the tumor, the patient's hesitatancy toward an operation, and good previous response to gonadotropin-releasing hormone (GnRH) agonist treatment, the patient received a six-cycle GnRH agonist treatment. Serum T levels returned to normal limits after administration of the first dose of GnRH agonist. At follow-up, serum hormone levels were all within the normal ranges consistent with menopause, but the size of the metastatic tumor was constant. The tumor was then completely excised pathologically proven to be a metastatic TSOT. CONCLUSIONS: Recurrent TSOT might be successfully detected using WBPET with [(11)C]acetate. In addition, GnRH agonist could be tried in patients with TSOT if initial responses were excellent and surgical intervention could not be performed.

Carbon Radioisotopes↗

PubMed2001

Laparoscopic bipolar coagulation of uterine vessels: a new method for treating symptomatic fibroids.

OBJECTIVE: To evaluate the effects of laparoscopic bipolar coagulation of uterine vessels in treating symptomatic fibroids. DESIGN: Prospective clinical study. SETTING: University-affiliated tertiary referral center. PATIENT(S): Eighty-seven women with symptomatic fibroids warranting surgical treatment and wanting to retain their uteri. INTERVENTION(S): Laparoscopic bipolar coagulation of uterine arteries and anastomotic sites of uterine arteries with ovarian arteries. MAIN OUTCOME MEASURE(S): Percentage reduction in the dominant fibroid size and clinical response evaluation. RESULT(S): Eighty-five (97.7%) of 87 patients underwent technically successful laparoscopic coagulation of uterine vessels without intraoperative complications. The mean follow-up time was 10.2 months. Symptomatic improvement was reported in 76 (89.4%) of 85 patients, including 18 (21.2%) with complete resolution of symptoms. Significant reductions in the dominant fibroid size (average, 76%) and the uterine volume (average, 46%) were sonographically demonstrated. Two patients conceived 4 and 9 months, respectively, after treatment. Three (3.5%) premenopausal women became postmenopausal postoperatively. CONCLUSION(S): Laparoscopic bipolar coagulation of uterine vessels appears to be a promising new method for treating fibroid-related menorrhagia and pelvic pain.

Adult↗

PubMed2001

Successful treatment of symptomatic arteriovenous malformation of the uterus using laparoscopic bipolar coagulation of uterine vessels.

OBJECTIVE: To report a case of symptomatic arteriovenous malformation (AVM) of the uterus that was successfully treated with laparoscopic bipolar coagulation of uterine vessels. DESIGN: Case report. SETTING: University-affiliated tertiary referral center. PATIENT(S): A 66-year-old woman with symptomatic AVM of the uterus. INTERVENTION(S): Laparoscopic bipolar coagulation of uterine vessels. MAIN OUTCOME MEASURE(S): Clinical symptoms, color Doppler sonographic examination, and pelvic magnetic resonance imaging. RESULT(S): Remarkable shrinkage of the lesion size, obvious decrease in all of the impedance measurements (pulsatility, resistance, velocity indexes [systolic/diastolic]), and freedom from symptoms. CONCLUSION(S): This modality is a new alternative method for the management of patients with symptomatic AVM of the uterus who do not respond to conservative treatment.

Aged↗

PubMed2001

Intraperitoneal cisplatin-based chemotherapy vs. intravenous cisplatin-based chemotherapy for stage III optimally cytoreduced epithelial ovarian cancer.

OBJECTIVE: To compare the survival between intraperitoneal cisplatin-based chemotherapy (IPCT) and intravenous cisplatin-based chemotherapy (IVCT) in stage III epithelial ovarian cancer with minimal residual disease (<1 cm) after primary debulking surgery. METHOD: One hundred and thirty-two patients with stage III epithelial ovarian cancer after optimal primary debulking surgery with minimal residual disease between April 1990 and March 1995 were entered into a randomized clinical trial in which IPCT or IVCT was administered at 3-week intervals. Patients in the IPCT arm received cisplatin-based (100 mg/m(2)) intraperitoneal chemotherapy. Patients in the IVCT arm received cisplatin-based (50 mg/m(2)) intravenous chemotherapy. The tumor response was assessed every 3 months. The hematological toxicity using the South West Oncology Group (SWOG) toxicity criteria was assessed. Catheter complications associated with intraperitoneal chemotherapy were also analyzed. RESULT: The estimated median survival in the IPCT group was 43 months (95% confidence interval, 34-54) and IVCT group was 48 months (95% confidence interval, 37-59). The hazard ratio of death was not statistically significant between IPCT and IVCT (hazard ratio, 1.13; 95% CI, 0.69-1.86; P=0.317). The frequencies of hematological toxic effects were significantly lower in the IPCT group than in the IVCT group. CONCLUSION: Intravenous and intraperitoneal chemotherapy are associated with equivalent survival in patients with minimal residual stage III epithelial ovarian cancer after optimal cytoreductive surgery.

Adult↗

PubMed2001

Laparoscopic bipolar coagulation of uterine vessels to treat symptomatic myomas in women with elevated Ca 125.

STUDY OBJECTIVE: To assess laparoscopic bipolar coagulation of uterine vessels (LBCUV) for symptomatic myomas in women with elevated CA 125 (>35 U/ml). DESIGN: Prospective, longitudinal study (Canadian Task Force classification II-1). SETTING: Private practice, university-affiliated hospital. PATIENTS: Forty-six women (age 30-50 yrs) with symptomatic myomas and elevated CA 125 level. INTERVENTION: Laparoscopic bipolar coagulation of uterine vessels performed over 10 months. MEASUREMENTS AND MAIN RESULTS: All patients underwent successful LBCUV and coagulation of anastomotic site of uterine arteries with ovarian arteries without intraoperative complication. One, 3, and 6 months after treatment, respectively, 52.2%, 65.2%, and 71.7% of women reported improvement in menorrhagia, 19.6%, 45.7%, and 56.5% noted improvement in dysmenorrhea, and 6.5%, 16.1%, and 38.7% had improvement in bulk-related symptoms. Average reduction in uterine volume was 9.1%, 16.9%, and 38.3% and average reduction in dominant myoma was 12.1%, 23.9%, and 59.1% at those times; the average reduction of CA 125 in all patients was 39.8, 75.4, and 126.1U/ml. CONCLUSION: Symptoms were improved and uterine volume and dominant myoma were reduced by LBCUV. The CA 125 level fell during follow-up in 40 patients (87.0%). Improvement in symptoms, especially menorrhagia, and shrinkage of uterine volume and dominant myoma seemed to be more pronounced in women with decreased than in those without decreased CA 125 after treatment (p = 0.045). The CA 125 level may be a valuable indicator for monitoring the efficacy of LBCUV.

Adult↗

PubMed2001

Vaginal expulsion of submucous myomas after laparoscopic-assisted uterine depletion of the myomas.

STUDY OBJECTIVE: To determine the safety and side effects that may be caused by laparoscopic-assisted uterine depletion (LAUD) of submucous myomas. DESIGN: Retrospective chart review and follow-up (Canadian Task Force classification II-2). SETTING: University-affiliated tertiary referral center. PATIENTS: Five hundred twenty women with symptomatic myomas warranting surgical treatment, who wished to retain their uteri. INTERVENTION: Laparoscopic bipolar coagulation of uterine arteries and anastomotic sites of uterine arteries with ovarian arteries. MEASUREMENTS AND MAIN RESULTS: Postoperative sonographs showed submucous myomas in 53 (10.2%) women. During follow-up for a mean of 8.6 months very few complications occurred; however, nine women (1.7%) experienced vaginal expulsion of myomas from 2 weeks to 5 months postoperatively. Four of them were readmitted within 43 days with high fever and fetid discharge, and cervical cultures revealed heavy growth of Escherichia coli in three. Vaginal myomectomy was performed in six patients, and one woman passed the myoma spontaneously. Histopathologic studies of these nine specimens showed that two had infarction, three had coagulative necrosis, and four had degeneration. After treatment, all nine women had normal menstruation and their symptoms resolved during follow-up of at least 3 months. CONCLUSION: In our experience LAUD led to satisfactory symptomatic improvement and reduction in myoma volume and few complications. If vaginal expulsion of submucous fibroids can be viewed as a side effect, we should pay close attention to women with submucous myomas, especially within 2 months of LAUD. Otherwise, more dangerous complications could occur.

Adult↗

PubMed2001

Addition of laparoscopic uterine nerve ablation to laparoscopic bipolar coagulation of uterine vessels for women with uterine myomas and dysmenorrhea.

STUDY OBJECTIVE: To assess the effectiveness of laparoscopic uterine nerve ablation (LUNA) in women with dysmenorrhea caused by uterine myomas treated by laparoscopic bipolar coagulation of uterine vessels (LBCUV). DESIGN: Prospective, randomized, longitudinal study (Canadian Task Force classification II-1). SETTING: Private practice, university-affiliated hospital. PATIENTS: Eighty-five women with uterine leiomyomas and associated dysmenorrhea. INTERVENTION: Laparoscopic bipolar coagulation of uterine vessels with or without LUNA. MEASUREMENTS AND MAIN RESULTS: Of 85 patients who entered the study, 41 were assigned to undergo LBCUV-LUNA (group A), which was successful in 40 (97.6%). In 44 women assigned to have LBCUV only (group B), 43 (97.7%) underwent successful surgery. Eighty women completed 1-, 3-, and 6-month follow-up (38 group A, 42 group B). The groups did not differ significantly in age, history of abdominopelvic surgery, intraperitoneal adhesions, endometriosis, concomitant surgery, and operating time. Seven (18.4%) of 38 women in group A and 12 (28.6%) of 42 in group B experienced lower abdominal pain postoperatively. Acceptable pain was defined as a score of zero or 1: 31 and 30 women in groups A and B reported scores of zero; 3 and 2 reported scores of 1; 4 and 8 reported scores of 2; zero and 2 reported scores of 3; and no patients reported scores of 4. The frequency and severity of postoperative pain were less in group A than in group B (both p <0.05). The efficacy of both methods was almost equal in shrinking the uterus and dominant myoma, and in improving menorrhagia and bulk-related symptoms. Dysmenorrhea improvement was 84.2% and 61.9% in groups A and B at 3 months and 92.1% and 73.8% at 6 months, respectively. This was more significant in group A than in group B (p <0.05). CONCLUSION: Our results suggest that LUNA may decrease postoperative ischemic pain and improve dysmenorrhea associated with uterine myomas treated by LBCUV.

Adolescent↗

PubMed2001

Nitric oxide induces extensive apoptosis in endometrial epithelial cells in the presence of progesterone: involvement of mitogen-activated protein kinase pathways.

During trophoblast invasion, luminal and glandular endometrial epithelial cells (EEC) have been found to undergo apoptosis through undetermined mechanisms. We postulate that nitric oxide (NO) and progesterone may mediate apoptosis in EEC because they are produced by trophoblasts at concentrations that can cause apoptosis in non-uterine cells. Using a cultured EEC line, RL95-2, we found that sodium nitroprusside (SNP) or S-nitroso-N-acetylpenicillamine (SNAP), two commonly used NO-releasing agents, caused the death of EEC in a dose-dependent manner and progesterone markedly enhanced NO-induced cytotoxicity. Cells treated with NO/progesterone showed a significant increase in the percentage of condensed nuclei, as detected by DAPI staining, and in caspase-3 activity, indicating that these cells underwent apoptosis. Immunoblot analysis revealed that SNP/NO could activate extracellular signal-regulated kinase (ERK) and, to a lesser extent, p38 mitogen-activated protein kinase (MAPK). While pretreatment with PD98059 (an ERK inhibitor) did not prevent cell death, the addition of SB203580 (a p38 MAPK inhibitor) effectively rescued the cells from NO/progesterone treatment. Moreover, SNP/NO-induced p38 MAPK activation was significantly up-regulated by progesterone. Our results demonstrate that NO and progesterone may synergistically activate p38 MAPK to induce apoptosis in EEC, a process that may facilitate implantation.

Apoptosis↗

PubMed2001

Legal and ethical considerations of assisted reproductive technology and surrogate motherhood in AOFOG countries.

With increasing use of assisted reproductive technologies (ART) and its related issues, the Ethics Committee of the Asia-Oceania Federation of Obstetrics and Gynecology (AOFOG), after discussion at its council meeting, took up the mission to understand the current legal and ethical aspects of this special subject in Asia-Oceania area before making proper recommendations. This Committee drafted a questionnaire to all 22 country member societies in 1995, and again conducted the same survey in 2000 to track changes in each country/region's laws and regulations. The results show that the current attitude and status of country member societies vary in a wide range and do not have formal legal codes in majority regulating the ethical aspects of ART. The use of ART and surrogacy is obviously affected by local traditions, popularity in the use of such techniques and cultural/religious concerns. The changes in 5 years are not major. Three countries do not as yet practice such techniques. However, liberalization of surrogate motherhood has become a trend. Five countries, compared with two only in 1995, are now available for surrogate motherhood, though regulated by strict criteria. Based on the data collected and issues discussed, a detailed guideline may not be generally applicable as each region has its own rules, reflecting differences in the management of ART, especially in the surrogate motherhood. This Committee therefore recommends that ART must be performed by a board certified gynecologist in a certification laboratory and surrogate motherhood must be used only for medical reasons and not be commercialized. The patients of this special group must be treated individually, based on this recommendation and the regulations of their own country/region.

Asia↗

PubMed2001

Flexible carbon nanotube membrane sensory system: a generic platform.

Multi-walled carbon nanotube membrane as obtained from soft lithography-mediated selective chemical-vapor deposition template approach has been successfully integrated with flexible elastomeric polydimethylsiloxane framework to fabricate microsensing devices. Two proof-of-concept experiments, namely high-sensitivity chemical gas sensing and electrochemical detection have been performed to demonstrate its potential as a useful generic platform for general purposes sensory system.

Air Pressure↗

PubMed2001

Primary epithelial ovarian carcinoma in Taiwanese women.

PURPOSE OF INVESTIGATION: Primary epithelial ovarian carcinoma is common in industrial countries but rare in the Orient. In fact, it is still a rare disease in Taiwan. In this article, we report the general data of Taiwanese patients with primary epithelial ovarian carcinoma. METHODS: In this retrospective study we used univariate and multivariate analysis models to analyze the prognosis of patients with surgically confirmed primary epithelial ovarian carcinoma. One hundred and ninety-four patients from 1990 to 1996 were identified and enrolled in this study. RESULTS: The mean follow-up time was 44.7 months with an interval between 15.1 months and 105.9 months. Univariate analysis showed postmenopausal status, advanced stage, presence of lymph node metastasis, poor differentiation, and suboptimal surgery as risk factors for disease recurrence and subsequent deaths. Multivariate analysis demonstrated stage as the most important factor correlated with recurrent disease (risk ratio: 7.303 and 5.409, respectively), followed by optimal surgery (RR: 2.447), and cellular differentiation (RR: 1.677). CONCLUSIONS: Our data on the Taiwan population were consistent with other reports of different races. Early detection for primary epithelial ovarian cancer is of great importance because stage is still the most important predictor in disease-free survival and disease-related deaths. Application of the most reliable and acceptable methods of screening is our goal in the next century after weighing benefits over costs.

Adenocarcinoma, Clear Cell↗

PubMed2001

Identifying local tumor variables for operable node-negative, margin-free patients with bulky cervical carcinoma of FIGO stage IB, IIA and IIB without adjuvant therapies.

PURPOSE: To identify local risk factors for FIGO IB, IIA and IIB bulky cervical squamous cell carcinoma (tumor size > or = 4 cm) patients with node-negative, margin-free tumors treated by radical hysterectomy, pelvic lymph node and para-aortic lymph node dissections without adjuvant therapies. MATERIALS AND METHODS: Thirty-four patients were recruited between 1976 and 1989 because they all declined any postoperative adjuvant therapy. The pathology reports showed that all the specimen margins were free from cancer cells with no para-aortic or pelvic lymph node metastases. The survival interval was calculated starting from the time of surgical intervention to the time of death or the end of this study in the year 2000. RESULT: Tumor variables including cell differentiation, depth of stromal invasion, parametrial invasion, vaginal invasion, uterine body invasion, age, and FIGO stage were analyzed. Only vaginal invasion showed statistical significance for decreasing patient disease-free survival in both univariate and multivariate analyses with p values of 0.003 and 0.002, respectively. CONCLUSION: For node-negative and margin-free patients with bulky cervical squamous cell carcinoma with operable stage IB and IIB, surgical intervention alone could suffice when no vaginal invasion is noted plus an 85% survival rate could be achieved. A prospective pilot study should be initiated although this study showed an excellent survival rate which is perhaps due to the limited number of cases.

Adult↗