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Biomedical subjects

H C Chen

Publications and source records attributed to H C Chen.

At least 19 recordsLinked to original sources
PubMed2006

A new technique for substernal colon transposition with a breast dissector: report of 39 cases.

This paper investigates the effectiveness of the breast dissector to create a substernal space for oesophageal reconstruction. The surgeon must be extremely careful while dissecting the tissue below the sternum in order to avoid pneumothorax. The endoscopically assisted preparation of the substernal route is safe but it requires appropriate training. A retrospective study on 68 patients who underwent oesophageal reconstruction was done analysing the patients' records. In 39 cases, the breast dissector was used. In 29 cases, the substernal tunnel was created with hand dissection only. All 68 colon segments were successfully transferred in the two groups of patients. In all 39 the cases where the breast dissector was used no pneumothorax followed. In 10 (34%) patients of the control group pneumothorax occurred. Concluding, no more pneumothorax has occurred during the substernal oesophageal reconstruction since we started using the breast dissector.

Adolescent↗
PubMed2006

Acute pancreatitis following antilymphocyte globulin therapy in a renal transplant recipient.

Acute pancreatitis is a rare complication following OKT3 therapy, which to our knowledge has never been reported in patients treated with antilymphocyte globulin (ALG). We herein report a case of a kidney transplantation patient who developed acute pancreatitis 2 days after treatment with ALG for grade IIb acute rejection. The symptoms subsided after discontinuing this drug. Resumption of ALG therapy triggered another episode of acute pancreatitis. Therefore, the clinical course strongly suggests that ALG was the etiological factor of acute pancreatitis in this particular patient.

Acute Disease↗
PubMed2006

Endothelin-1 regulates parathyroid hormone expression of human parathyroid cells.

OBJECTIVE: Parathyroid cells synthesize and release endothelin-1 (ET-1). ET-1 displays an in vitro inhibitory effect on basal parathyroid hormone (PTH) secretion and also counteracts PTH hypersecretion stimulated by low calcium. Such effects are further demonstrated in vivo, independent of the changes in calcitonin. We propose that ET-1 may regulate the pathogenesis of uremic hyperparathyroidism. However, this was not directly demonstrated in human parathyroid glands. DESIGN: Hyperplastic parathyroid glands are obtained from the surgical operation for uremic hyperparathyroidism. Cells are isolated by enzyme digestion and treated with ET-1, and are assessed for PTH mRNA expression. PTH in the plasma and the medium is measured by a newly developed method to detect the whole PTH (1-84). PATIENTS: Uremic patients with severe secondary hyperparathyroidism and ultrasonography-proved hypertrophy of parathyroid glands received elective surgical approaches under general anesthesia. The resected glands were immediately taken to the laboratory for fresh isolation. MEASUREMENTS: Following ET-1 treatment, PTH mRNA expression is evaluated by RT-PCR method. ET-1 is detected with radioimmunoassay kit and PTH is measured by a new commercially available Duo PTH kit. RESULTS: ET-1 exhibited a dose-dependent inhibitory effect (from 10(-12) - 10(-7) M) on PTH mRNA expression of parathyroid cells, either in the basal or in the low-calcium-stimulated states. Release of PTH into the medium is also gradually inhibited by the increase in ET-1 concentrations. CONCLUSIONS: Our results demonstrate that ET-1 attenuates PTH mRNA expression in freshly isolated human parathyroid cells, and PTH release is also decreased. This result is consistent with our previously reported in vitro and in vivo experiments.

Adult↗
PubMed2006

Decreased B cells and IgA-secreting B cells partially explain the high prevalence of IgA deficiency in dialysis patients.

AIMS: We previously reported 2 hemodialysis (HD) patients with recurrent infections and selective immunoglobulin A deficiency (IgAD). We further demonstrated that serum IgA levels were lower and the prevalence of IgAD was higher in uremic patients. The exact mechanisms of IgAD in uremic patients largely remained unclear. In some patients, it was caused by anti-IgA antibody neutralization and subsequent destruction. We performed the present study to survey if there is any defect in IgA production. MATERIALS AND METHODS: 288 patients were initially included for examination of serum immunoglobulins. 16 normal persons, 16 dialysis patients without IgAD, and 12 dialysis patients with IgAD were enrolled after the initial examination. Blood was drawn into heparinized tubes. WBC counts and lymphocyte percentage were examined by a CBC counter. Lymphocytes were separated by the Ficoll-Paque method. Flow cytometry was utilized to isolate the B cell and IgA-secreting B cell after staining with CD 19 phycoerythrin and FITC-conjugated rabbit anti-human IgA antibody. RESULTS: There is no significant difference between WBC counts or total lymphocyte counts of these 3 groups. However, we found a lower percentage of total lymphocyte counts in dialysis patients, either with or without IgAD. The total B cell numbers were lower in dialysis patients with IgAD. In addition, there were fewer IgA-secreting B cells in dialysis patients with IgAD. CONCLUSION: Decreased B cell and IgA-secreting B cell counts are seen in uremic patients with IgAD. This, in turn, indicates that there might be a defect of IgA production in some patients, rather than IgA destruction by anti-IgA antibodies as seen in some other patients. Further study is needed to investigate the mechanisms of decreased B cells and IgA-secreting B cells.

Adult↗
PubMed2005

Induction of matrix metalloproteinase-9 in mice during Toxocara canis larvae migration.

The relationships between inflammation in organs with Toxocara canis larval migration and matrix metalloproteinase-9 (MMP-9) were investigated following the infection of mice with 1,000 infective eggs. Gelatinase activity was defined by gelatin zymography, optimum pH, inhibitor specificity and Western blot analysis. MMP-9 activity was present in the lungs, liver, muscles, and brain during T. canis larval migration. This enzyme had a molecular weight of about 94 kDa and showed maximum activity in the pH range of 6-8. The increased MMP-9 proteinases coincided with larval recovery and the degree of inflammation among the four organs. These results suggest that MMP-9 may be associated with the inflammatory reaction to larval toxocariasis during early migration, and may therefore be a useful marker during T. canis larvae migration.

Animals↗
PubMed2005

Exaggerated relative nasal-temporal asymmetry of macular capillary blood flow in patients with clinically significant diabetic macular oedema.

AIMS: To compare the macular capillary blood flow of patients with clinically significant diabetic macular oedema (DMO) with that of non-diabetic subjects and to determine the relation between blood flow and capillary leakage in patients with DMO. METHODS: The sample comprised 45 non-diabetic subjects (mean age 59 years) and 18 type 2 patients with clinically significant DMO (mean age 60 years). Macular capillary blood flow measurements were acquired using the Heidelberg retina flowmeter (HRF) and a 10 degrees x2.5 degrees scan field centred on the fovea. Fluorescein angiography was undertaken on each of the diabetic patients after the completion of HRF measurements. RESULTS: Temporal macular capillary blood flow was significantly lower for the patients with clinically significant DMO compared with age matched non-diabetic subjects (ANCOVA, p = 0.0011) while relative nasal-temporal asymmetry of macular capillary blood flow was significantly higher (p = 0.0125). Nasal-temporal asymmetry of macular capillary blood flow was significantly higher for the patients with DMO and capillary leakage within the scan area (two tailed t test, p = 0.0071). Macular capillary blood flow was always lower in areas of DMO and capillary leakage. CONCLUSION: Capillary blood flow was reduced in areas of DMO and capillary leakage, suggesting the presence of a localised perturbation of capillary blood flow regulation.

Aged↗
PubMed2005

Sweet's syndrome as an initial presentation in systemic lupus erythematosus: a case report and review of the literature.

Malar or discoid rash is the most frequent specific cutaneous lesion for systemic lupus erythematosus (SLE). Neutrophilic dermatosis as an initial presentation in SLE is unusual. We describe a 38-year old female patient who primarily suffered from erythematous tender plaques and fever. Examination of skin biopsy of the plaques showed dense neutrophilic infiltration in the dermis. Polyarthritis, heavy proteinuria, photosensitivity and positive antinuclear antibodies (ANA > 1:1280) concluded the diagnosis of SLE. The plaques disappeared completely after treatment with systemic corticosteroids. To our knowledge, this is the first reported SLE patient with Sweet's syndrome as the initial presentation in literature review.

Adult↗
PubMed2005

7-84 parathyroid hormone fragments are proportionally increased with the severity of uremic hyperparathyroidism.

AIMS: Recent progress in PTH assay has revealed that the intact PTH assay kit in current use does not differentiate between the truncated 7-84 PTH molecule and the 1-84 PTH molecule. In our series, we examined the effectiveness of a new PTH assay as a noninvasive method of evaluating severity of uremic hyperparathyroidism. METHODS AND MATERIALS: Two hundred and seventy hemodialysis (HD) patients recruited from three HD centers were included and divided into subgroups according to the conventional iPTH assay results. Pre-dialysis blood samples were collected and subjected to two different PTH assays: "intact" PTH assay (iPTH) and "whole" PTH (wPTH) assay. Two biochemical markers of bone remodeling were also examined. RESULTS: In all cases, PTH levels determined by the wPTH assay were in the average 32.3% lower than those determined by the iPTH assay. The difference of the results of the two PTH assay methods, which indicated the portion of 7-84 PTH fragments of the total PTH molecules measured with the iPTH assay, was gradually increased while the severity of uremic hyperparathyroidism increased. Biochemical markers of bone formation/resorption showed a similar change. CONCLUSION: The portion of the 7-84 PTH fragments and markers of increased bone turnover increased in proportion to the severity of uremic hyperparathyroidism. This finding disproves the hypothetical role of 7-84 PTH fragments alone as the noninvasive marker of low-turnover bone disease in HD patients.

Adult↗
PubMed2004

Aloe-emodin induced in vitro G2/M arrest of cell cycle in human promyelocytic leukemia HL-60 cells.

In this study, we have evaluated the chemopreventive role of aloe-emodin in human promyelocytic leukemia HL-60 cells in vitro by studying the regulation of proliferation, cell cycle and apoptosis. Aloe-emodin inhibited cell proliferation and induced G2/M arrest and apoptosis in HL-60 cells. Investigation of the levels of cyclins B1, E and A by immunoblot analysis showed that cyclin E level was unaffected, whereas cyclin B1 and A levels increased with aloe-emodin in HL-60 cells. Investigation of the levels of cyclin-dependent kinases, Cdk1 and 2, showed increased levels of Cdk1 but the levels of Cdk2 were not effected with aloe-emodin in HL-60 cells. The levels of p27 were increased after HL-60 cells were cotreated with various concentrations of aloe-emodin. The increase of the levels of p27 may be the major factor for aloe-emodin to cause G2/M arrest in these examined cells. Flow cytometric assays and DNA fragmentation gel electrophoresis also confirmed aloe-emodin induced apoptosis in HL-60 cells. The levels of caspase-3 were increased after HL-60 cells were cotreated with 10 microM aloe-emodin for 12, 24, 48, and 72 hours. Taken together, aloe-emodin therefore appears to exert its anticarcinogenesis properties by inhibiting proliferation and inducing cell cycle arrest and apoptosis underwent activation of caspase-3 in human leukemia HL-60 cells.

Anthraquinones↗
PubMed2004

RH locus contraction in a novel Dc-/D-- genotype resulting from separate genetic recombination events.

BACKGROUND: The rare phenotypes Dc- and D-- lack the expression of E/e and CcEe antigens, respectively; their cotransmission in a single family has not been reported. STUDY DESIGN AND METHODS: Six members of a Chinese family with two exhibiting the Dc- phenotype were studied using standard serologic methods. Rh genotypes were analyzed by Southern blot, and RH loci, by exon PCR. Rh transcripts were characterized by gene-specific RT-PCR and sequencing. RESULTS: Although Rh typing detected two members as Dc- homozygotes, RFLP analysis and exon PCR showed them to be Dc- heterozygotes with a partial deletion of RHCE. cDNA sequencing showed the expression in the family of normal RHD and RHCe as well as hybrid transcripts, RHD(1-9)/RHCE(10) and RHCE(1-3)/RHD(4-10). Thus, the Dc- members had the genotype of Dc-/ D-- and expressed both hybrid genes that were inherited from their parents, respectively. DISCUSSION: This is the first demonstration in a family that the Dc- and D-- complexes neither are linked with a normal RHD or RHCE gene. The segregation of these two different hybrid genes with single break points suggests their independent genetic origin and provides molecular insights into the dynamic nature of genomic rearrangements leading to RH locus contraction.

Adult↗
PubMed2004

Dehydroepiandrosterone suppresses interleukin 10 synthesis in women with systemic lupus erythematosus.

OBJECTIVE: To study the effects of dehydroepiandrosterone (prasterone, DHEA) 200 mg/day on cytokine profiles in adult women with active systemic lupus erythematosus (SLE). METHODS: In a double blind, randomised, placebo controlled study conducted as part of a larger multicentre study, 30 adult women with active SLE received oral DHEA 200 mg/day or placebo for 24 weeks. Baseline prednisone (<10 mg/day) and other concomitant SLE medications were to remain constant. The levels of cytokines including interleukin (IL) 1, IL2, interferon gamma, IL4, and IL10 were determined by ELISA. The mean change from baseline to 24 weeks of therapy was analysed. RESULTS: The two groups (DHEA n = 15; placebo n = 15) were well balanced for baseline characteristics. Only IL1beta and IL10 could be detected in the serum of lupus patients; however, there was no significant mean (SD) difference in serum IL1beta before and after treatment (9.94 (8.92) v 9.20 (6.49) pg/ml). IL10 demonstrated a greater and significant reduction from baseline (9.21 (9.66) to 1.89 (1.47) pg/ml in the DHEA treatment group). CONCLUSIONS: In a 24 week study of adult Chinese women with mild to moderate SLE, treatment with DHEA 200 mg once daily resulted in significant reduction of serum levels of IL10. This finding may suggest why DHEA could significantly reduce lupus flares.

Adolescent↗
PubMed2004

Design and testing of a fluorescence glucose sensor which incorporates a bioinductive material.

One main hurdle in the development of implantable biosensors is that their lifetime is limited by scar tissue formation around the implant. One way to ameliorate this issue would be to use a bioinductive coating to allow normal tissue ingrowth around the sensor. Here, we report design, development and in vitro testing of a prototype fluorescence-based glucose sensor that incorporates a bioinductive material at its tip. Glucose is sensed via a fluorescence-based assay system (Amplex reagent) which is confined to a small chamber separated from the bulk glucose solution by a semipermeable membrane. Excitation is provided by a 530 nm laser, while the emitted light is detected by a photomultiplier tube. In vitro testing of this prototype was done in the presence and absence of a bioinductive material covering the membrane at the sensor/solution interface. In response to a step change in glucose concentration, the output of the sensor increased linearly over time due to accumulation of fluorescent marker molecules as glucose diffused into the recording chamber. The slope of this response increased linearly with increasing glucose concentration, with a sensitivity if 2.1 x 10(-4) V/min per ml glucose/dl solution. The presence of the bioinductive layer did not alter the function of the sensor at the lowest glucose concentrations tested, although responses to higher concentrations saturated, presumably because of depletion of the Amplex reagent within the chamber. In summary, we report that the use of a bioinductive material in an implantable biosensor does not appreciably alter sensor function.

Biosensing Techniques↗
PubMed2004

Flap prefabrication - the bridge between conventional flaps and tissue-engineered flaps.

Flap prefabrication is one of the most exciting areas in Plastic Surgery because of its bridging role between conventional reconstructive surgery and tissue engineering. Using this technique,tissues such as bone, cartilage, skin and muscle can be preassembled to form precise composites that will fit any defect. In pre-lamination, for example, an ear may be created by burying cartilage underneath forearm skin and later harvested as a skin-cartilage composite free flap to replace the missing part. Vascular induction is yet another means of customising flaps where new blood supply is introduced to create transplantable tissue. For example, bone chips wrapped in avascular carrier such as muscle can become vascularised grafts. Our experiment describes jejunal prefabrication in a rat model using the same technique. Intestinal segments wrapped in muscle flaps become independent of their mesenteric blood supply by "parasitising" on the muscle's blood supply. This idea arose from our initial observations that intestinal segments transferred to the neck to reconstruct the oesophagus could survive accidental disruption of the pedicle if sufficient time had elapsed. Clearly, the bowel had picked up new blood supply from its bed. Subsequently, jejunal prefabrication was used to reconstruct the oesophagus in a patient in whom there were no recipient vessels for free jejunal transfer. The pedicled latissimus dorsi muscle flap was used as a carrier for the jejunum. Another application of this idea could be in the area of allogeneic trachea or pancreatic transplantation, since present-day techniques have yet to overcome problems such as insufficient vascularity and unpredictable transplant survival. Future applications incorporating biomaterials and cultured cells will usher in the era of tissue-engineered flaps.

Animals↗
PubMed2003

Correlation of a scanning laser derived oedema index and visual function following grid laser treatment for diabetic macular oedema.

AIM: To correlate change of an oedema index derived by scanning laser tomography with change of visual function in patients undergoing grid laser photocoagulation for clinically significant diabetic macular oedema (DMO). METHODS: The sample comprised 24 diabetic patients with retinal thickening within 500 micro m of the fovea. Inclusion criteria included a logMAR visual acuity of 0.25, or better. Patients were assessed twice before a single session of grid laser treatment and within 1 week of, and at 1, 2, 4, and 12 weeks after, treatment. At each visit, patients underwent logMAR visual acuity, conventional and short wavelength automated perimetry (SWAP), and scanning laser tomography. Each visual function parameter was correlated with the mean oedema index. The mean oedema index represented the z-profile signal width divided by the maximum reflectance intensity (arbitrary units). A Pearson correlation coefficient (Bonferroni corrected) was undertaken on the data set of each patient. RESULTS: 13 patients exhibited significant correlation of the mean oedema index and at least one measure of visual function for the 10 degrees x 10 degrees scan field while 10 patients correlated for the 20 degrees x 20 degrees scan field. Seven patients demonstrated correlation for both scan fields. Laser photocoagulation typically resulted in an immediate loss of perimetric sensitivity whereas the oedema index changed over a period of weeks. Localised oedema did not impact upon visual acuity or letter contrast sensitivity when situated extrafoveally. CONCLUSIONS: Correlation of change of the oedema index and of visual function following grid laser photocoagulation was not found in all patients. An absence of correlation can be explained by the localised distribution of DMO in this sample of patients, as well as by differences in the time course of change of the oedema index and visual function. The study has objectively documented change in the magnitude and distribution of DMO following grid laser treatment and has established the relation of this change to the change in visual function.

Aged↗
PubMed2003

Ruptured renal microaneurysms complicated with a retroperitoneal abscess for a patient with systemic lupus erythematosus.

Renal artery aneurysm is extremely rare among patients with systemic lupus erythematosus.(SLE). Herein, we report on a 22-year-old male lupus patient who presented with acute abdominal pain, anemia and subsequent hypertension. Abdominal computed tomography revealed a peri-renal hematoma over the right kidney. A renal angiography revealed bilateral renal microaneurysms. The patient subsequently developed a right-side retroperitoneal abscess 4 weeks after hematoma formation and received an emergent laparotomy with drainage. Subsequent culture ofthe abscess-derived fluid revealed the presence of Proteus mirabilis and Escherichia coli. Following appropriate antipyretic and immunosuppressive drugs therapy, the patient recovered successfully. To the best of our knowledge, this is the first report of SLE associated with a retro-peritoneal abscess probably secondary to a ruptured renal microaneurysm.

Abdominal Abscess↗