Biomedical subjects

Chee-Yin Chai

Publications and source records attributed to Chee-Yin Chai.

At least 55 records · Page 3Linked to original sources

PubMed2004

Incidence of dehiscence of the facial nerve at surgery for middle ear cholesteatoma.

OBJECTIVE: To identify the incidence of dehiscence of the facial nerve in patients undergoing surgery for cholesteatoma and to describe its relevance with iatrogenic facial nerve injury. STUDY DESIGN AND SETTING: This was a retrospective study including 117 tympanoplasties with or without mastoidectomy performed in 49 men and 66 women. RESULTS: The presences of FND after exenteration of disease are 33.3% of total surgical procedures, 33% of the initial procedures, and 37.5% of the revision procedures. The locations of facial nerve dehiscence were 87.2% in only the tympanic segment, 7.7% in only the vertical segment, and 5.1% in both the tympanic and vertical segments. CONCLUSIONS AND SIGNIFICANCE: The incidence of facial nerve dehiscence is high (33.3%) in our study. The surgeon should keep in mind that the location of facial nerve dehiscence with cholesteatoma is comparable with the most common area of iatrogenic facial nerve injury during otologic surgery.

Adolescent↗

PubMed2004

Epidermal growth factor expression in middle ear cholesteatoma.

Middle ear cholesteatoma is destructive to auditory ossicles and temporal bone, and treatment usually requires surgical removal of all epithelial content. Epidermal growth factor (EGF) can stimulate the growth and differentiation of a variety of mammalian cells, including epithelial cells. Our study used the avidin-biotin complex technique to evaluate the expression of EGF in 40 cases of middle ear cholesteatoma (active cholesteatoma, 31 cases; inactive cholesteatoma, 9 cases) and 34 normal postauricular skin samples. In middle ear cholesteatoma, EGF was expressed in squamous epithelium in 21 cases (53%), fibroblasts in two cases (5%), and cholesteatoma endothelium in two cases (5%). In normal postauricular skin, EGF was expressed in squamous epithelium in 14 samples (41%), fibroblasts in one sample (3%), and endothelium in none. No statistical difference in EGF expression was found between cholesteatoma and normal postauricular skin samples. These results show that the distribution of EGF in middle ear cholesteatoma is not deranged and that the progression of cholesteatoma might be induced by the release of factors from the cholesteatoma matrix via autocrine stimulation, or by inflammatory cells of the subepithelial tissue through paracrine stimulation, or in both of these ways.

Adult↗

PubMed2004

Unusual upper gastrointestinal bleeding due to late metastasis from renal cell carcinoma: a case report.

A case of recurrent massive upper gastrointestinal bleeding originating from metastatic renal cell carcinoma is reported. A 63-year-old woman underwent right nephrectomy 9 years previously and experienced no recurrence during follow-up. A gradually enlarging ulcerative tumor over the bulb of the duodenum and four subsequent episodes of massive bleeding from this tumor occurred between June 2001 and March 2002. The patient underwent surgery in April 2002 for intractable bleeding from the tumor. Renal cell carcinoma metastasis to the duodenum was confirmed from the surgical specimen. Upper gastrointestinal bleeding due to malignancy is very rare and the duodenum is the least frequently involved site. Furthermore, a solitary late renal cell carcinoma metastasis 9 years after a nephrectomy is extremely uncommon. This case suggests that life-long follow-up of renal cell carcinoma patients is necessary, owing to unpredictable behavior and the possibility of long disease-free intervals. In nephrectomized patients suffering from gastrointestinal bleeding, complete evaluation, especially endoscopic examination, is indicated. The possibility of late recurrent renal cell carcinoma metastasis to the gastrointestinal tract should be kept in mind, although it is rare. If the patient is fit for surgery, metastatectomy is the first choice of treatment.

Carcinoma, Renal Cell↗

PubMed2004

Schwannoma of the nasal septum: a case report.

Schwannoma is a neurogenic tumor arising from the sheath of myelinated nerves. Only 4% of schwannomas located in the head and neck region involve the sinonasal tract, and those arising from the nasal septum are exceedingly rare. We report a case of a 55-year-old male who presented with only right nasal obstruction. Computerized tomography and clinical examination suggested a benign tumor before the tumor was completely removed by transnasal endoscopic surgery. When encountering a mass in the nasal cavity, schwannoma should be borne in mind in the differential diagnosis. We discuss the clinical presentation, histologic features, differential diagnosis, and therapeutic options for such a rare lesion.

Diagnosis, Differential↗

PubMed2004

Chloroma of the testis after allogeneic peripheral blood stem cell transplantation: a case report.

Chloroma, or granulocytic sarcoma, is a rare extramedullary solid hematologic cancer that affects many sites, usually in concert with acute myeloid leukemia. It is infrequently associated with other myeloproliferative disorders or chronic myelogenous leukemia. Chloroma of the testis after allogeneic bone marrow transplantation is particularly sparsely represented in the literature. It is often incorrectly diagnosed as malignant lymphoma, especially large-cell lymphoma, owing to the similarity of the histologic morphology, scanty eosinophilic myelocytes, and no or overlooked history of leukemia. Although erroneous diagnosis is decreasing with the advent of ancillary studies, the diagnosis of chloroma continues to be a nightmare for pathologists. It is thus suggested that an appropriate panel of marker studies be performed in conjunction with clinical correlation and circumspection to avoid reaching a misleading conclusion and improper treatment of patients. We report an interesting case of a 35-year-old male with a clinical history of chronic myelogenous leukemia post allogeneic peripheral blood stem cell transplantation and complete molecular remission, who was found to have chloroma of the left testis.

Adult↗

PubMed2004

Extra-adrenal pheochromocytoma presenting with life-threatening ventricular tachycardia: a case report.

Extra-adrenal pheochromocytoma develops in paraganglion chromaffin cells of the sympathetic nervous system. It probably represents at least 15% of adult and 30% of childhood pheochromocytomas. Although electrocardiographic abnormalities occur in up to 75% of patients with pheochromocytoma, there are only three other reported cases of pheochromocytoma that initially presented with ventricular tachycardia. In this report, we describe a 64-year-old woman with an abdominal para-aortic extra-adrenal pheochromocytoma who presented with pulseless ventricular tachycardia and needed electrical defibrillation initially to keep vital signs. The 24-hour urine vanillylmandelic acid was 35.8 mg. Computerized tomography showed a left retroperitoneal mass. The postoperative course was uneventful. Pheochromocytoma was proved by histologic study.

Female↗

PubMed2004

Effects and interactions of low doses of arsenic and UVB on keratinocyte apoptosis.

Although arsenic and ultraviolet light B (UVB) are both causes for skin cancers, lesions of arsenic-induced Bowen's disease are often confined to sun-protected skin. UVB may play a modulatory role in skin carcinogenesis by arsenic. The purpose of this study was to evaluate the effects and interactions of arsenic and UVB on cell cycle progression and apoptosis. Cultured human keratinocytes were treated with sodium arsenite (1 microM) and/or UVB (50 mJ/cm(2)) irradiation in different combinations: (i) arsenic alone, (ii) UVB alone, (iii) arsenic followed by UVB (As-UVB), and (iv) UVB followed by arsenic (UVB-As) treatments. Cell cycle analysis and BrdU pulsing revealed S phase arrest in all treatment groups and growth arrest in As-UVB and UVB-As groups. The terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling assay showed a higher apoptosis rate in the UVB-As group as compared to that of the As-UVB and UVB groups. UVB irradiation significantly decreased Bcl-2 expression. In either the As-UVB or the UVB-As group, the expression of Bcl-2 was further suppressed as compared to the UVB group. The caspase-3, -8, and -9 relative activities were all increased in the UVB group; however, arsenic significantly enhanced caspase-8 and -3 relative activities in UVB-irradiated keratinocytes (the UVB-As group). Pretreatment with the caspase inhibitor(s) rescued the keratinocytes viability to different degrees with the least in the UVB-As group. Our findings revealed that arsenic enhances UVB-induced keratinocyte apoptosis via suppression of Bcl-2 expression and stimulation of caspase-8 activity. Combined UVB and arsenic treatment resulted in the antiproliferative and proapoptotic effects in keratinocytes. Our results provide the explanation for the rare occurrences of arsenical cancers in the sun-exposed skin and the potential therapeutic role of UVB in arsenic-induced Bowen's disease.

Apoptosis↗

PubMed2004

Differential changes in endothelin-1 and endothelial nitric oxide synthase gene expression in rats with a chronic high pulmonary flow.

The expressions of endothelin-1 (ET-1) and endothelial nitric oxide synthase were assessed in the lung of adult Wistar rats (n = 6/group) undergoing an abdominal aortocaval shunt to increase pulmonary blood flow for 4, 8 or 12 weeks. The shunt resulted in significant medial hypertrophy of the pulmonary artery without significant increases in pulmonary and systemic arterial pressure. A competitive reverse transcriptase-polymerase chain reaction demonstrated significant increases in pulmonary preproET-1 mRNA at 12 weeks (mean +/- standard error of the mean; shunt, 1.82 +/- 0.12; sham, 1.00 +/- 0.15; P < 0.05) and in pulmonary endothelial nitric oxide synthase mRNA at both 8 weeks (shunt, 1.57 +/- 0.12; sham, 1.00 +/- 0.18; P < 0.05) and 12 weeks (shunt, 1.89 +/- 0.18; sham, 1.00 +/- 0.13; P < 0.05). In addition, western blot analysis showed increases in pulmonary endothelial nitric oxide synthase protein by 126% and 164% at 8 and 12 weeks, respectively, in the shunt animals. However, the plasma ET-1 concentrations and the lung ET-1 contents were unchanged. These results indicate that endothelial nitric oxide synthase gene expression was upregulated, prior to that of ET-1, at the transcriptional level during pulmonary vascular remodeling in this chronic shunt model.

Animals↗

PubMed2004

Effects of helium-neon laser on levels of stress protein and arthritic histopathology in experimental osteoarthritis.

OBJECTIVE: To investigate the effect of low-power laser therapy on levels of stress proteins (SPs) in experimental arthritis and their relation to the bioeffects on arthritic cartilage repair. DESIGN: A total of 42 rats with similar degrees of induced arthritis evaluated by means of bone scan were divided randomly into two groups. In the treated group, 21 rats received helium-neon laser treatment; in the control group, 21 rats received sham laser treatment. The changes in chondrocytes of SPs were measured by electrophoresis of proteins extracted from chondrocytes of arthritic cartilage at various time periods. The histopathologic changes and the presence of SP of arthritic cartilage were identified by hematoxylin and eosin stain and by immunostains of SP72 antibody individually from frozen sections of arthritic cartilage. RESULTS: SP density increased markedly in rats after laser treatment and was closely related to the repair of arthritic cartilage. Furthermore, the pathohistology of arthritic cartilage improved significantly with the decline of SP levels in the follow-up period. CONCLUSION: Helium-neon (632 nm) low-power laser can enhance SP production in arthritic chondrocytes. The extragenic production of SP is well correlated with the therapeutic effect of low-power laser in preserving chondrocytes and the repair of arthritic cartilage in rats.

Animals↗

PubMed2003

Role of MUC1 and MUC5AC expressions as prognostic indicators in gastric carcinomas.

BACKGROUND AND OBJECTIVES: The aim of this study is to clarify the relationship between the expression of MUC1 and MUC5AC mucins and the clinicopathological features in human gastric carcinomas using the mouse monoclonal antibodies VU-4H5 and Clone 45M1, respectively. Furthermore, the possibility of using phenotypes (MUC1+/MUC5AC+, MUC1+/MUC5AC-, MUC1-/MUC5AC-, MUC1-/MUC5AC+) to predict prognosis of the patients is evaluated. METHODS: Formalin-fixed, paraffin wax-embedded tissues from 76 cases of gastric cancer were examined for the expression of MUC1 and MUC5AC mucin antigens immunohistochemically using the avidin-biotin-peroxidase method. RESULTS: Of the 76 cases, MUC1 and MUC5AC immunoreactivities were observed in 49 (64.5%) and in 32 (42.1%) of gastric carcinoma tissues, respectively. MUC1 expression was significantly correlated to the depth of invasion, lymph node metastasis, peritoneal dissemination, and tumor stage. On the other hand, MUC5AC was inversely associated with depth of invasion, lymph node metastasis, liver metastasis, and tumor stage. Multivariate analyses indicated that tumor stage and MUC1 mucin expression were independently correlated with overall survival. The patients with MUC1+/MUC5AC- antigen staining in carcinoma tissues showed the lowest survival rate among four phenotypes. In contrast, the patients with MUC1-/MUC5AC+ antigen staining in carcinoma tissues showed the highest survival rate. CONCLUSIONS: Altogether these data suggest that combined evaluation of MUC1 and MUC5AC mucin staining may be clinically helpful to predict outcome in patients with gastric cancer.

Adult↗

PubMed2003

Penile verrucous carcinoma successfully treated by intra-aortic infusion with methotrexate.

OBJECTIVES: Penile verrucous carcinoma is characterized by aggressive local growth and a low metastatic potential. Lower abdominal aortic infusion chemotherapy has the main advantage of delivering a very high concentration of an anticancer drug to the whole pelvic area, including the penis, and is especially suitable to treat penile verrucous carcinoma. METHODS: From 1991 to 2000, 4 cases of penile verrucous carcinoma were treated by continuous intra-aortic infusion with methotrexate (50 mg) every 24 hours, for an average of 10 days. Citrovorum factor (6 mg) was given intramuscularly every 6 hours during the period of methotrexate infusion. RESULTS: After treatment, 3 patients achieved complete remission. They were living disease free 10 years, 10 months, 6 years, 9 months, and 1 year, 8 months after therapy. CONCLUSIONS: Intra-aortic infusion chemotherapy is a simple and effective method for penile verrucous carcinoma with the unique advantage of preserving cosmetic and functional integrity. It may be considered an effective alternative treatment for penile verrucous carcinoma. By using this simple method many unnecessary penectomies can be avoided.

Adult↗

PubMed2003

Paraganglioma of the urinary bladder: a case report.

Paragangliomas of the urinary bladder are very rare. To date, there are no reliable methods for predicting their clinical behavior, so long-term follow-up is required. We describe a paraganglioma of the urinary bladder in a 32-year-old male who presented with painless gross hematuria. Abdominal ultrasonography revealed a protruding mass with hematoma over the right lateral wall of the urinary bladder. The tumor was not completely resected by transurethral resection of bladder tumor (TURBT) due to intermingling with the bladder wall. Follow-up I131-metaiodobenzylguanidine was performed 3 weeks after surgery and suspected incomplete resection lesions were noted. Histologic examination of the tumor indicated paraganglioma of the urinary bladder. We also provide a brief review of the literature for comparison.

3-Iodobenzylguanidine↗

PubMed2003

Leiomyoma of the urinary bladder: a case report.

Leiomyoma of the urinary bladder is a rare tumor and constitutes 35% of benign mesenchymal bladder tumors. Herein, we report a case of leiomyoma of the bladder. A 32-year-old female was incidentally found to have an abnormal bladder mass on abdominal ultrasound during work-up for infertility. Bimanual examination then revealed a mass on the right side near the bladder neck area. On cystoscopic examination, an external compression mass covered with normal bladder mucosa could be seen at the right lateral wall. Computerized tomography revealed a homogeneous solitary tumor protruding into the urinary bladder from the right lateral wall without enlarged lymph nodes. Magnetic resonance imaging showed an intraluminal round mass at the right aspect of the urinary bladder, leading to suspicion of an intramural neurogenic or mesenchymal tumor. Surgical exploration was performed via a lower midline incision and a 5.0 x 4.5 x 2.2 cm mass was excised. The pathologic diagnosis was leiomyoma of the bladder. We discuss the diagnosis and management of leiomyoma of the bladder and briefly review the literature.

Adult↗

PubMed2003

Expression of epidermal growth factor receptor in human middle ear cholesteatoma.

Middle ear cholesteatoma is destructive to auditory ossicles and temporal bone, and treatment usually includes surgical removal of all epithelial content in the tympanomastoid cavity. Epidermal growth factor receptor (EGFR) is a 170 kd to 180 kd transmembrane glycoprotein and its distribution density is related to the ability of the keratinocytes to differentiate and their state of differentiation. We used the avidin-biotin complex technique and EGFR monoclonal antibody to evaluate the expression of EGFR in 29 cases of cholesteatoma and 34 samples of normal postauricular skin. Of patients with cholesteatoma, 79% (23 cases) had EGFR-positive cells in the basal layer, 66% (19 cases) in the parabasal layer, and 62% (18 cases) in the upper layer of the epithelial tissue. Among patients with normal postauricular skin, 85% (29 cases) had EGFR-positive cells in the basal layer, 79% (27 cases) in the parabasal layer, and 79% (27 cases) in the upper layer of the epithelial tissue. No statistical difference in EGFR expression between each layer of cholesteatoma and postauricular skin was noted. However, there was an intensity gradient of positive EGFR immunoreactivity from the basal to the higher layers in cholesteatoma. Our results showed that the distribution of EGFR in middle ear cholesteatoma is not deranged, but is similar to that in normal skin tissue.

Adult↗

PubMed2003

Intra-abdominal desmoplastic small round cell tumor with elevated serum CA 125: a case report.

Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive tumor usually involving the peritoneum. It occurs more commonly in young males and is characterized by distinctive clinical, histologic, and immunophenotypic features. The histogenesis of DSRCT remains unknown. Coexpression of epithelial, mesenchymal, and neural antigens in the same cell provides evidence that DSRCT may arise from a primitive pluripotent stem cell with divergent differentiation. Recently, according to cytogenetic studies, some authors have proposed that the divergent differentiation of DSRCT may be the result of the fusion of Ewing's sarcoma gene and Wilms' tumor suppressor gene. Clinically, an elevated serum CA 125 concentration is found in some patients with DSRCT. We present the case of a 29-year-old man with diffuse intra-abdominal DSRCT and elevated serum CA 125 concentration and briefly review the relevant literature.

Abdominal Neoplasms↗

PubMed2003

Hyalinizing spindle cell tumor with giant rosettes: a case report.

Hyalinizing spindle cell tumor with giant rosettes (HSCTGR) is characterized by both giant rosette-like structures with collagen cores sparsely distributed throughout the tumor and fibromyxoid stroma. It is a rare low-grade sarcoma with indolent behavior, and wide excision with long-term follow-up is the best treatment. Although originally considered a distinct entity, it is now regarded as a variant of low-grade fibromyxoid sarcoma. We present a case of HSCTGR arising in the deep soft tissue of the left knee in a 50-year-old woman and provide a brief review of the literature for comparison.

Female↗

PubMed2002

Cancer immunotherapy using Sindbis virus replicon particles encoding a VP22-antigen fusion.

Alphavirus vectors have emerged as a strategy for the development of cancer vaccines and gene therapy applications. The availability of a new packaging cell line (PCL), which is capable of generating alphavirus replicon particles without contamination from replication-competent virus, has advanced the field of vaccine development. This replication-defective vaccine vector has potential advantages over naked nucleic acid vaccines, such as increased efficiency of gene delivery and large-scale production. We have developed a new strategy to enhance nucleic acid vaccine potency by linking VP22, a herpes simplex virus type 1 (HSV-1) tegument protein, to a model antigen. This strategy facilitated the spread of linked E7 antigen to neighboring cells. In this study, we created a recombinant Sindbis virus (SIN)-based replicon particle encoding VP22 linked to a model tumor antigen, human papillomavirus type 16 (HPV-16) E7, using a stable SIN PCL. The linkage of VP22 to E7 in these SIN replicon particles resulted in a significant increase in the number of E7-specific CD8(+) T cell precursors and a strong antitumor effect against E7-expressing tumors in vaccinated C57BL/6 mice relative to wild-type E7 SIN replicon particles. Furthermore, a head-to-head comparison of VP22-E7-containing naked DNA, naked RNA replicons, or RNA replicon particle vaccines indicated that SINrep5-VP22/E7 replicon particles generated the most potent therapeutic antitumor effect. Our results indicated that the VP22 strategy used in the context of SIN replicon particles may facilitate the generation of a highly effective vaccine for widespread immunization.

Animals↗

PubMed2002

Effects of increased pulmonary flow on the expression of endothelial nitric oxide synthase and endothelin-1 in the rat.

The purpose of the study was to assess whether increased pulmonary flow and subsequent development of pulmonary vascular remodelling could alter the expression of endothelial nitric oxide synthase (eNOS) and endothelin-1 (ET-1) in the rat lung. Nine 42-day-old Wistar rats underwent abdominal aortocaval shunt to increase pulmonary blood flow for 12 weeks. The shunt resulted in significant medial hypertrophy of pulmonary artery without significant alterations in pulmonary or systemic blood pressure. Using competitive reverse transcription-PCR, significant increases in the preproET-1 mRNA expression and eNOS mRNA expression in the lungs of rats with abdominal aortocaval shunt were detected. Increased eNOS protein in the lung of shunt rats was also found by Western blot analysis. However, the plasma ET-1 concentration in the pulmonary artery (sham: 5+/-0.7 pg/ml; shunt: 6+/-0.8 pg/ml) or the lung ET-1 content (sham: 218+/-41 ng/g protein; shunt: 224+/-40 ng/g protein) was unchanged. There was an elevated immunohistochemical expression of eNOS, but not ET-1, in the pulmonary vascular endothelium in rats with the shunt. These results suggest that eNOS and ET-1 may be involved in remodelling prior to the development of pulmonary hypertension.

Animals↗