Biomedical subjects

Ching-Fai Kwok

Publications and source records attributed to Ching-Fai Kwok.

5 recordsLinked to original sources

PubMed2006

Characterization of pancreatic stem cells derived from adult human pancreas ducts by fluorescence activated cell sorting.

AIM: To isolate putative pancreatic stem cells (PSCs) from human adult tissues of pancreas duct using serum-free, conditioned medium. The characterization of surface phenotype of these PSCs was analyzed by flow cytometry. The potential for pancreatic lineage and the capability of beta-cell differentiation in these PSCs were evaluated as well. METHODS: By using serum-free medium supplemented with essential growth factors, we attempted to isolate the putative PSCs which has been reported to express nestin and pdx-1. The Matrigel(TM) was employed to evaluate the differential capacity of isolated cells. Dithizone staining, insulin content/secretion measurement, and immunohistochemistry staining were used to monitor the differentiation. Fluorescence activated cell sorting (FACS) was used to detect the phenotypic markers of putative PSCs. RESULTS: A monolayer of spindle-like cells was cultivated. The putative PSCs expressed pdx-1 and nestin. They were also able to differentiate into insulin-, glucagon-, and somatostatin-positive cells. The spectrum of phenotypic markers in PSCs was investigated; a similarity was revealed when using human bone marrow-derived stem cells as the comparative experiment, such as CD29, CD44, CD49, CD50, CD51, CD62E, PDGFR-alpha, CD73 (SH2), CD81, CD105(SH3). CONCLUSION: In this study, we successfully isolated PSCs from adult human pancreatic duct by using serum-free medium. These PSCs not only expressed nestin and pdx-1 but also exhibited markers attributable to mesenchymal stem cells. Although work is needed to elucidate the role of these cells, the application of these PSCs might be therapeutic strategies for diabetes mellitus.

Bone Marrow Cells↗

PubMed2005

Diffuse soft tissue emphysema in anorexia nervosa: a case report.

OBJECTIVE: Anorexia nervosa (AN) is an eating disorder that occurs mainly among young females and its prevalence has increased in recent decades. METHODS: We reported a patient with AN with spontaneous diffuse soft tissue emphysema and bicytopenia, both of which are very rare complications of AN. Our patient, a 20-year-old woman, had lost 41.6% of her previous body weight within 9 months. Her body mass index was 10.8 and amenorrhea had persisted for 5 months. RESULTS: After admission, she was diagnosed with AN-restrictive subtype. She was noted to have crunching sounds in the neck and upper chest wall during hospitalization. A chest X-ray and chest computed tomography scan both revealed diffuse soft tissue emphysema including subcutaneous emphysema, pneumomediastinum, and pneumoretroperitoneum. DISCUSSION: Diffuse soft tissue emphysema improved gradually and completely resolved on the 21st day of hospitalization. This condition seems to be benign and only a short period of hospitalization is required.

Adult↗

PubMed2003

Intra-arterial calcium stimulation test for detection of insulinomas: detection rate, responses of pancreatic peptides, and its relationship to differentiation of tumor cells.

The selective intra-arterial calcium stimulation test has greatly facilitated the precise regionalization of insulinomas smaller than 2 cm, which noninvasive techniques (ultrasound [US], computed tomography [CT], magnetic resonance imaging [MRI]) often fail to localize. This study examined not only the role of the test in the localization of insulinomas, but also the responsiveness of 3 beta-cell peptides (insulin, C peptide, and proinsulin) and their relationship to the degree of differentiation of the tumor cells, using percentage decrease of both proinsulin/insulin (P/I) and proinsulin/C peptide (P/C) ratios after stimulation as indices. Ten consecutive surgically proven insulinoma patients each received an injection of calcium into the arteries supplying the pancreas after standard selective angiography and beta-cell peptide levels were measured in samples taken from the right hepatic vein before and 30, 60, 90, 120, and 180 seconds after each injection prior to operation. After surgery, the expressions of the calcium sensing receptor (CaSR) on the resected tumors were assessed by immunohistochemistry. Intra-arterial calcium stimulation with sampling either for insulin or for C peptide correctly predicted the site of insulinoma in 8 of 9 patients or in 7 of 8 patients if the 2 big malignant insulinomas were excluded; thus, the detection rate of this test was 89% and 88%, respectively. Calcium administration stimulated a marked and prompt release of insulin and C peptide simultaneously. Both peaked within 30 to 60 seconds, then declined gradually thereafter, remaining above the baseline at 180 seconds. The magnitude of increase correlated well with the corresponding percentage decrease of P/I and P/C ratios. The response of proinsulin was much less. Immunohistochemistry demonstrated variable membraneous staining for CaSR in normal pancreatic islets and in about 9% of the total normal beta cells, whereas staining in tumor cells was only minimally detectable. We conclude that selective intra-arterial calcium stimulation with hepatic venous sampling either for insulin or for C peptide is a highly sensitive method for the preoperative localization of small insulinomas. Calcium injection stimulates a brisk response of insulin, C peptide, and proinsulin simultaneously and the magnitude of increase of both insulin and C peptide appears to be correlated well with the degree of differentiation of the tumor cells. The exact mechanism by which calcium provokes the release of beta-cell peptides is less clear and whether the CaSR is involved in the mechanism of its action requires further study.

Adult↗

PubMed2002

Effects of Ginkgo biloba extract on the proliferation of vascular smooth muscle cells in vitro and on intimal thickening and interleukin-1beta expression after balloon injury in cholesterol-fed rabbits in vivo.

Restenosis may develop in response to cytokine activation and smooth muscle cell proliferation. Ginkgo biloba extract (EGb) has been used to treat cardiovascular and cerebrovascular diseases. In the present study, the effects of EGb on the growth of cultured vascular smooth muscle cells (VSMC), as well as on the expression of interleukin-1beta (IL-1beta) and the intimal response in balloon-injured arteries of cholesterol-fed rabbits, were investigated. Using bromodeoxyuridine incorporation as an index of cell proliferation, EGb was found to inhibit serum-induced mitogenesis of cultured rat aorta VSMC in a dose-dependent manner. In vivo, EGb and probucol ( positive control) reduced the atheroma area in thoracic aortas of male New Zealand white rabbits fed a 2% cholesterol diet for 6 weeks with balloon denudation of the abdominal aorta being performed at the end of the third week. Intimal hyperplasia, expressed as the intimal/medial area ratio, in the abdominal aortas was significantly inhibited in the both the EGb group (0.61 +/- 0.06) and the probucol group (0.55 +/- 0.03) compared to the C group (0.87 +/- 0.02). In the balloon-injured abdominal aorta, both EGb and probucol significantly reduced IL-1beta mRNA and protein expression and the percentage of proliferating cells. The inhibitory effects of EGb on the intimal response might be attributed to its antioxidant capacity. EGb may have therapeutic potential for the prevention of restenosis after angioplasty.

Angioplasty, Balloon↗

PubMed2002

A reappraisal of the ovine corticotropin-releasing hormone stimulation test in the differential diagnosis of Cushing's syndrome: a comparison with the standard high-dose dexamethasone suppression test.

BACKGROUND: We evaluated the diagnostic efficacy of the ovine corticotropin-releasing hormone (oCRH) stimulation test in the differential diagnosis of Cushing's syndrome and compared it with the standard high-dose dexamethasone suppression test. METHODS: Twelve healthy volunteers and 30 with Cushing's syndrome (12 Cushing's disease and 18 adrenal Cushing's syndrome) were enrolled. Plasma ACTH and cortisol levels were measured before and after an intravenous bolus of 100 microg oCRH. Plasma and urinary free cortisol were determined after standard 2-day high-dose dexamethasone suppression. RESULTS: Basal cortisol in 12 patients with Cushing's disease and 18 with adrenal Cushing's syndrome were higher than the control group (21.4 +/- 0.1 microg/dl vs. 22.3 +/- 0.5 microg/dl vs. 9.1 +/- 1.5 microg/dl; p < 0.01). In Cushing's disease, basal plasma ACTH value was significantly higher than those with adrenal disease (61.1 +/- 1.4 pg/ml vs. 6.2 +/- 4.5 pg/ml; p < 0.01). After oCRH, plasma ACTH and cortisol significantly increased, with a mean of 2.0 +/- 0.2-fold (range 1.0-2.4) and 1.6 +/- 0.1-fold (range 1.1-2.1), respectively over the basal values in patients with Cushing's disease, and 11 (90%) attained a significant ACTH (1.5-fold) or cortisol (1.2-fold) response. All except 2 (89%) with adrenal Cushing's showed no apparent change in response to oCRH. Dexamethsone suppressed urinary free cortisol by 90% in 8 (67%) with Cushing's disease, but all (100%) with adrenal Cushing's syndrome were resistant. No patient with Cushing's disease was refractory to oCRH and dexamethasone, while none with adrenal Cushing's syndrome was responsive to both. Combination of both tests could achieved a specificity of 100% for Cushing's disease and adrenal Cushing's, when these 2 tests gave concomitant positive or negative results, respectively. CONCLUSIONS: The oCRH test is a reliable examination in the differential diagnosis of Cushing's syndrome and is comparable to the high-dose dexamethasone test. A highest discrimination could be achieved when both are used.

ACTH Syndrome, Ectopic↗