Biomedical subjects

Christopher Cheng

Publications and source records attributed to Christopher Cheng.

13 recordsLinked to original sources

PubMed2006

Inverted papilloma of urinary bladder: is long-term cystoscopic surveillance needed? A single center's experience.

OBJECTIVES: To review all cases of urinary bladder inverted papilloma (IP) in our institution and determine the need for cystoscopic surveillance. IP is an uncommon benign tumor of the urinary tract. Its multiplicity, recurrence, and association with transitional cell carcinoma (TCC) suggest possible malignant potential, leading to conflicting clinical conclusions regarding the need for surveillance. METHODS: All consecutive patients from January 1991 to December 2004 with IP were included in this study. A single pathologist performed the histologic review. The patients had undergone cystoscopy and ultrasound evaluation of the kidneys every 6 months. RESULTS: Of the 52 patients, 45 were men and 7 were women. The average age at presentation was 58.9 +/- 11.8 years (range 30 to 79). No patient had a synchronous or previous bladder tumor. The most common complaint was macroscopic hematuria. Ten cases were incidental findings during bladder ultrasonography or cystoscopy. All were solitary tumors, most commonly found at the bladder neck. The average follow-up period was 62 +/- 23 months, with no recurrence. One case of subsequent noninvasive papillary TCC developed 15 months later. The initial histologic findings had revealed cytologic atypia, with suspicious urine cytology findings. On review, it was more compatible with TCC with an inverted pattern. CONCLUSIONS: Although our cases exhibited benign biologic behavior, the presence of cytologic atypia and suspicious urine cytology require exclusion of TCC with an inverted pattern. Thus, in histologically proven solitary bladder IP with no associated TCC, cystoscopic surveillance may not be necessary.

Adult↗

PubMed2006

Is high-grade prostatic intraepithelial neoplasia on needle biopsy different in an Asian population: a clinicopathologic study performed in Singapore.

OBJECTIVES: To evaluate the incidence, pathologic findings, and follow-up of high-grade prostatic intraepithelial neoplasia (HGPIN) in a series of prostate core biopsies from Singaporean men. METHODS: We studied isolated HGPIN diagnosed on prostate core biopsies and the incidence of cancer discovered in men who had undergone repeat biopsies from 1999 to 2003 at the Department of Pathology, Singapore General Hospital. RESULTS: Of 1219 men undergoing prostate needle biopsy, 56 (4.6%) had isolated HGPIN. Most cases affected a single prostate core (44 cases, 78.6%). Twenty-nine men (51.8%) underwent repeat biopsies. Cancer was discovered in 7 (24.1%) of the 29 men within two repeat biopsies. CONCLUSIONS: The incidence of isolated HGPIN on prostate needle core biopsies in Asian men, as well as the likelihood of subsequent cancer detection, are comparable to the rates reported for Western populations. The relatively low yield of cancer detection on repeat biopsy supports the need to re-evaluate recommendations for rebiopsy strategies.

Aged↗

PubMed2005

Penile cancer: current challenges.

Penile cancer remains a formidable challenge in many developing countries because of its high incidence and the advanced disease stage at diagnosis. For early penile cancer, surgery alone offers a high cure rate. Penile sparing therapies are proposed as alternative treatment options for select patients with the added advantages of preservation of body image and improved quality of life. The optimal management of lymph node disease remains controversial. The role of the sentinel lymph node biopsy, lymphatic mapping, prophylactic lymphadenectomy and the template for lymph node dissection are discussed. For advanced, metastatic penile cancer, more effective and less toxic chemotherapy is needed. This may be coupled with palliative surgery or radiotherapy for the primary tumor and inguinal disease.

Adult↗

PubMed2004

Routine vascular control using the Hem-o-lok clip in laparoscopic nephrectomy: animal study and clinical application.

BACKGROUND AND PURPOSE: During laparoscopic nephrectomy (LPN), a stapling device is often used for vascular control, especially of the renal vein. Herein, we report our experience using a polymer clip (Hem-o-lok) for routine control of the vessels during LPN in the animal and clinical setting. PATIENTS AND METHODS: Fifty ablative and fifteen live-donor nephrectomies were performed in domestic pigs. Hem-o-lok clips (10 mm; Weck Closure System, Research Triangle Park, NC) were routinely used for vascular control. In addition, from January 2001 to July 2002, 46 patients underwent hand-assisted laparoscopic (HAL) (N=40) or laparoscopic (N=6) nephrectomy for renal disease or donor nephrectomy. Venous control was achieved solely by the Hem-o-lok clips where at least two clips were applied on the patient side. Arterial control was obtained by the Hem-o-lok clips either alone or in combination with the metal clips. The technical difficulty in obtaining vascular control, transfusion requirement, and clinical outcome were evaluated. RESULTS: In the animal study (total 65 nephrectomies), individual vascular control was obtained by the Hem-o-lok clip in all cases except two, where vascular injury during dissection necessitated endoscopic stapling of renal hilum or open conversion. The warm ischemic time for animal donor kidney harvest was uniformly <2 minutes. In the clinical study, arterial control was obtained mostly by a combination of Hem-o-lok and metal clips. Venous control using the Hem-o-lok was successful in all 46 cases without any slipping of clips or uncontrolled bleeding. The mean operating time was 148 minutes. No open conversion was required. The transfusion rate was 6.5% (N=3), with none of the transfusions being related to inadequacy of vascular control using the Hem-o-lok. Major complications included deep vein thrombosis and postoperative retroperitoneal hemorrhage (same patient) and acute respiratory distress syndrome (N = 1). The mean postoperative stay was 5.2 days (range 1-20 days). CONCLUSION: The Hem-o-lok is a reliable and economical device for vascular control in laparoscopic renal surgery.

Animals↗

PubMed2004

Evaluation of Hypocrellin B in a human bladder tumor model in experimental photodynamic therapy: biodistribution, light dose and drug-light interval effects.

Hypocrellin B (HB), a monomeric perylenequinone pigment, is a promising second-generation photosensitizer for photodynamic therapy. We have evaluated the efficacy of HB mediated PDT by experimenting with various drug-light intervals, based on the biodistribution analysis in human bladder tumor (MGH cell line) models. Tumor growth rates were assessed at 10-day post treatment followed by morphometric analysis. Biodistribution of HB was evaluated using spectrofluorophotometry analysis (Ex: 480 nm, Em: 620-630 nm). The level of HB peaked at 6 h postinjection in tumor, peritumoral skin and normal muscle followed by a decline over the next 42 h. Concurrently, the ratio of drug in tumor versus skin was relatively low at all times in comparison to tumor to muscle ratio. In serum, concentration of HB peaked at 1 h. Almost 88% of its original uptake level was cleared at 48 h. The level of PDT response revealed a strong dependence on the drug-light intervals (DLI) and light dose. For both high and low fluence/fluence rate, comparable tumor response was observed at 1 h DLI; treated tumors exhibited significant tumor regression compared to 6 and 24 h DLI. The absence of tumor response was observed at 24 h DLI even at high light dose (100 J/cm(2); 100 mW/cm(2)). Tumor response detected at low light dose (12 J/cm(2); 12 mW/cm(2)) at short DLI suggests that the tumor vasculature is a more sensitive target compared to the cellular compartment of the tumor, correlating significantly with the bioavailability of the drug in serum. Therefore, HB mediated PDT effect is characteristics of a predominantly vascular mediated effect. This study confirms that for short drug-light intervals, PDT seems to target tumor vasculature, which contributes to tumor destruction.

Animals↗

PubMed2004

The 3rd Conference on Asian Trends in Prostate Cancer Hormone Therapy.

From its inception in 2001, the Conference on Asian Trends in Prostate Cancer Hormone Therapy has served as an annual forum for Asian urologists to compare data on prostate cancer and to discuss issues regarding the use of hormone therapy. The 3rd conference, held in Tokyo in December 2003, began with participants from China, Indonesia, Japan, Korea, Singapore, and Taiwan presenting QOL data deriving from a survey of patients with prostate cancer. For this purpose, each country translated the Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire into its own language. Although the surveys conducted in each country included a heterogeneous cohort of patients and gave very mixed results, the trial of FACT-P in Asian countries seemed propitious and in future may provide insights that could prove beneficial to patients. Day 2 of the conference included 2 discussions, focusing on the most appropriate number of biopsy cores and the implementation of prospective trials involving the collaboration of Asian countries, respectively. In the latter discussion, although a varied assortment of proposals were put forth, the participants generally agreed that any collaborative study must be a prospective outcome study conducted in a relatively short time not exceeding 2-3 years, and that patient registration should be done using the Internet.

Androgen Antagonists↗

PubMed2003

Optimal excitation-emission wavelengths for autofluorescence diagnosis of bladder tumors.

Tissue autofluorescence depends on endogenous fluorophores in the tissue, which undergo a change associated with malignant transformation. This change can be detected as an alteration in the spectral profile and intensity of autofluorescence. Our purpose was to determine the optimal excitation and emission wavelengths for autofluorescence diagnosis of bladder cancer. A total of 52 bladder tissue specimens were obtained from 25 patients undergoing mucosal biopsies or surgical resections of bladder tumors. Light-induced autofluorescence measurements were performed to study the spectroscopic differences between normal and malignant bladder tissue. Fluorescence excitation wavelengths varying from 220 to 500 nm were used to induce tissue autofluorescence, and emission spectra were measured in the 280-700 nm range. These spectra were then combined to construct 2-dimensional fluorescence excitation-emission matrices (EEMs). Significant changes in fluorescence intensity of EEMs were observed between normal and tumor bladder tissues, the most marked differences being at the excitation wavelengths of 280 and 330 nm. The diagnostic algorithm based on the combination of the fluorescence peak intensity ratios of I(350)/I(470) at 280 nm excitation and I(390)/I(470) at 330 nm excitation yielded a sensitivity of 100% [95% confidence interval (CI) 0.95-1.0] and specificity of 100% (95% CI 0.90-1.0). The results of the present fluorescence EEM study demonstrate that autofluorescence spectroscopy can distinguish malignant from normal bladder tissue and that excitation wavelengths of 280 and 330 nm are the most significant for differentiation between normal and malignant bladder mucosae with a high degree of diagnostic accuracy.

Aged↗

PubMed2003

A case of juxtaglomerular cell tumor associated with membranous glomerulonephritis.

The association of membranous glomerulonephritis with benign tumors is rarely described. This report represents, to the best of our knowledge, the first documented account of the simultaneous occurrence of juxtaglomerular cell tumor of the kidney and membranous glomerulonephritis. A young Chinese woman presented with hypertension and proteinuria, whereupon investigations disclosed a renal tumor. She underwent surgical resection, and histologic examination of the tumor revealed CD34-positive uniform polygonal cells with accompanying mast cells, disposed in sheets with focal papillary pattern punctuated by cytokeratin-positive tubular structures. Characteristic rhomboid crystalline granules were identified ultrastructurally. The kidney adjacent to the tumor showed features of membranous glomerulonephritis and hypertensive arteriopathy. Proteinuria improved following tumor resection, but the patient had persistent hypertension attributable to renal hypertensive arteriopathy. This report also highlights the recently described observation of CD34 positivity in juxtaglomerular cell tumors.

Adult↗

PubMed2003

Gender differences in self-construal: how generalizable are Western findings?

The authors used the Twenty Statements Test in 2 studies to investigate gender and country differences in the spontaneous self-descriptions of 811 college students from Hong Kong, India, Nepal, Nigeria, and Zimbabwe and 136 secondary school students from Taiwan and Hong Kong. The authors performed statistical analysis and found no significant gender differences in the percentage of responses classified as belonging to the idiocentric self in either study. However, the authors found significant Country effects in both studies for responses classified as representing the idiocentric self and some aspects of the collective self, and the authors found significant Country x Gender effects involving all 4 categories of the idiocentric self and the collective self for the college students. These findings raise questions about the generalizability of Western findings that males are more likely to espouse an independent conception of self than females. However, as the authors predicted, females were more likely to use small group self-descriptions than their male peers.

Adult↗

PubMed2003

Macro-microscopic fluorescence of human bladder cancer using hypericin fluorescence cystoscopy and laser confocal microscopy.

The early detection of carcinoma is very essential for the diagnosis and prognosis of a bladder cancer patient. In this study we have investigated the use of hypericin as a fluorescent tumour marker and laser confocal microscopy as a diagnostic tool to aid the diagnosis of such cancers. Both cellular and clinical studies have been conducted. In the cellular studies, we have compared two bladder cell lines for the uptake and sub-cellular localization of hypericin. It was found that there was a rapid uptake and clearance of hypericin and significant localization in mitochondria and lysosomes. The study also revealed that there was a time-dependent increase in fluorescence intensity in bladder cells. The optimum localization was found to be 2-4 h post drug incubation. In the clinical study, consisting of 30 patients, both white light and fluorescence cystoscopy were performed after hypericin instillation. Biopsies taken from fluorescing regions were imaged using the confocal microscope. The order of fluorescence was detected to be as follows: normal < inflammation < grade 1 < grade 2 < CIS < grade 3. It was also found that the fluorescence intensity increased with the stage of the disease thereby enabling the determination of the degree of invasiveness of cancer. This enables the use of hypericin as a prognostic marker and laser confocal microscopy as a tool to aid in diagnosis of bladder cancer.

Anthracenes↗

PubMed2003

Novel photodynamic diagnosis of bladder cancer: ex vivo fluorescence cytology using hypericin.

In this study we have evaluated the use of hypericin ex vivo urine fluorescence cytology as a non-invasive method for detecting early bladder cancers. To date this is the first study reported using this technique with hypericin. Urine samples from patients with early bladder cancers were processed for fluorescence cytology by incubation with hypericin, a novel photosensitizer. Normal urine samples incubated with hypericin served as normal controls. Laser confocal microscopy and spectroscopy was used to detect the fluorescence in the exfoliated low-grade urothelial tumor cells. Fluorescence cytology was considered positive if hypericin fluorescence of the low-grade urothelial tumor cells was detected to be stronger (>8.5 times) compared to the baseline fluorescence established for normal urine samples. Automated analysis for an objective reproducible outcome appears possible. The possibility of detection of malignant urothelial cells in early cancer makes ex vivo fluorescence cytology promising for routine diagnostic screening.

Anthracenes↗

PubMed2002

Asian trends in prostate cancer hormone therapy.

The first Conference on Asian Trends in Prostate Cancer Hormone Therapy was held in September 2001 to serve as a forum for Asian urologists to compare data on prostate cancer and discuss issues regarding the use of hormone therapy. The conference revealed that due to various cultural and philosophical factors, differences exist in prostate cancer management among the Asian countries. In addition, a lack of databases on hormone therapy was exposed in some countries. It was noted that many decisions in the treatment of prostate cancer are influenced by the strategies adopted in Western countries, and that attempts to formulate uniform guidelines for the Asian region have hitherto been unsuccessful. The main findings of the conference are reported in this review.

Androgen Antagonists↗

PubMedDate not supplied

Prostate cancer control--aims of the UICC Asia Regional Office Consortium.

Cancer of the prostate remains at relatively low incidence in Asia but rates are increasing rapidly in some countries and specific populations so that measures for control need our attention. Little is known about risk factors, although vegetables and phytoestrogens may be protective and fat, meat and dairy products may increase the risk. Physical exercise may have preventive effects, while tobacco and alcohol appear to have no consistent relationship. The lack of clear lifestyle targets means that emphasis needs to be placed on screening for various prostate specific antigen parameters and clinical treatment, whether hormonal, radio or surgical, alone or in combination. While there is a massive literature for the Western world, the limited literature available for Asia means that cooperation to obtain a standardized data base is a high priority if the most effective measures for the specific populations of Asian countries are to be identified and put into practice.

Asia↗