Wen-Ming Hsu

In vitro analysis of a hepatic device with intrinsic microvascular-based channels

A novel microfluidics-based bilayer device with a discrete parenchymal chamber modeled upon hepatic organ architecture is described. The microfluidics network was designed using computational models to provide appropriate flow behavior based on physiological data from human microvasculature. Patterned silicon wafer molds were used to generate films with the vascular-based microfluidics network design and parenchymal chamber by soft lithography. The assembled device harbors hepatocytes behind a nanoporous membrane that permits transport of metabolites and small proteins while protecting them from the effects of shear stress. The device can sustain both human hepatoma cells and primary rat hepatocytes by continuous in vitro perfusion of medium, allowing proliferation and maintaining hepatic functions such as serum protein synthesis and metabolism. The design and fabrication processes are scalable, enabling the device concept to serve as both a platform technology for drug discovery and toxicity, and for the continuing development of an improved liver-assist device.

Long-term prognosis of patients with biliary atresia: a 25 year summary.

Objective: The purpose of this study was to delineate the long-term prognosis of biliary atresia (BA) in Taiwan. Study Design: From 1976 to 2000, 185 children were diagnosed with BA, 22 underwent exploratory laparotomy without Kasai operation, and 163 underwent Kasai operation, of which 141 cases had long-term follow-up and formed the basis of this study. The outcome was analyzed. Results: Among the 141 BA children studied who underwent Kasai operation, 115 (81.6%) had recoloration of stools, and 86 (61.0%) became jaundice-free (bilirubin <20 μmol/L). The resolution of jaundice and the absence of repeated cholangitis contributed to better outcome. Five and 10 year survival rates with native liver were 35% and 31%, respectively. Liver transplantation was performed in 19 patients (all but 2 with a living-related donor), and 15 (79%) survived. Five and 10 year overall survival rates for BA patients were 41.9% and 40.2%, respectively. Conclusions: The study delineated the long-term outcome of BA in an Asian country other than Japan. Survival with native liver after a Kasai operation in Taiwan was similar to that in the American and European series. Limited donors for liver transplantation in the years of the study accounted for the poor overall prognosis of BA patients in this series.

Retrograde Dissection of the Vascular Pedicle in Toe Harvest

A retrograde approach to dissection of the vascular pedicle in toe-to-hand transfer is presented, along with a simplified view of the vascular anatomy of the first web space. This approach has several advantages. First, the dominant vascular supply to the toe is elucidated early in the procedure, allowing for less unnecessary dissection of an inadequate pedicle. This also eliminates the need for preoperative arteriography. Furthermore, in cases where a lengthy pedicle is not required, retrograde dissection dispenses with harvest of a proximal vessel, which will not be needed for the transfer, and destructive dissection of the foot can be minimized.

Expression of Hepatocyte Transporters and Nuclear Receptors in Children With Early and Late-Stage Biliary Atresia

To investigate how the liver adapts to chronic obstructive cholestasis, liver samples from infants with early- and late-stage cholestasis were analyzed for changes in the levels of hepatocyte transporters and nuclear receptors. At early-stage cholestasis, most canalicular transporters and sinusoidal uptake transporters were downregulated, including bile salt export pump (BSEP, ABCB11), multidrug resistant protein 3 (MDR3, ABCB4), multidrug-resistant associated protein 2 (MRP2, ABCC2), sodium-dependent taurocholate cotransporting polypeptide (NTCP, SLC10A1), organic anion transporter (OATP, SLCO1A2), and nuclear receptor farnesoid X receptor (FXR, NR1H4). At late-stage cholestasis, FXR-BSEP levels returned to normal, MDR3 and MDR1 (ABCB1) were upregulated, and MRP-2 was downregulated. In addition, alternative sinusoidal efflux transporters, organic solute transporter alpha/beta (OSTα/β) and MRP4 were upregulated, and pregnane X receptor (PXR, NR1I2) levels decreased. Cytochrome enzyme P450 7A1 was markedly downregulated at both early and late-stage cholestasis. An analysis of the long-term prognosis of 18 patients revealed lower PXR and constitutive androstane receptor (CAR, NR1I3) levels in the poor prognosis group. In conclusion, at long-term cholestasis, hepatocyte bile efflux was through sinusoidal and canalicular transporters, with FXR-BSEP levels maintained and PXR downregulated. Low PXR and CAR levels were associated with poor prognosis.

Autophagy: A double-edged sword in Alzheimer's disease

Autophagy is a major protein degradation pathway that is essential for stress-induced and constitutive protein turnover. Accumulated evidence has demonstrated that amyloid-β (Aβ) protein can be generated in autophagic vacuoles, promoting its extracellular deposition in neuritic plaques as the pathological hallmark of Alzheimer’s disease (AD). The molecular machinery for Aβ generation, including APP, APP-C99 and β-/γ-secretases, are all enriched in autophagic vacuoles. The induction of autophagy can be vividly observed in the brain at early stages of sporadic AD and in an AD transgenic mouse model. Accumulated evidence has also demonstrated a neuroprotective role of autophagy in mediating the degradation of aggregated proteins that are causative of various neurodegenerative diseases. Autophagy is thus widely regarded as an intracellular hub for the removal of the detrimental Aβ peptides and Tau aggregates. Nonetheless, compelling data also reveal an unfavorable function of autophagy in facilitating the production of intracellular Aβ. The two faces of autophagy on the homeostasis of Aβ place it in a very unique and intriguing position in AD pathogenesis. This article briefly summarizes seminal discoveries that are shedding new light on the critical and unique roles of autophagy in AD and potential therapeutic approaches against autophagy-elicited AD.

Mucin glycosylating enzyme GALNT2 regulates the malignant character of hepatocellular carcinoma by modifying the EGF receptor.

Extracellular glycosylation is a critical determinant of malignant character. Here, we report that N-acetylgalactosaminyltransferase 2 (GALNT2), the enzyme that mediates the initial step of mucin type-O glycosylation, is a critical mediator of malignant character in hepatocellular carcinoma (HCC) that acts by modifying the activity of the epidermal growth factor receptor (EGFR). GALNT2 mRNA and protein were downregulated frequently in HCC tumors where these events were associated with vascular invasion and recurrence. Restoring GALNT2 expression in HCC cells suppressed EGF-induced cell growth, migration, and invasion in vitro and in vivo. Mechanistic investigations revealed that the status of the O-glycans attached to the EGFR was altered by GALNT2, changing EGFR responses after EGF binding. Inhibiting EGFR activity with erlotinib decreased the malignant characters caused by siRNA-mediated knockdown of GALNT2 in HCC cells, establishing the critical role of EGFR in mediating the effects of GALNT2 expression. Taken together, our results suggest that GALNT2 dysregulation contributes to the malignant behavior of HCC cells, and they provide novel insights into the significance of O-glycosylation in EGFR activity and HCC pathogenesis.

Up-Regulation of Fas Ligand Expression by Human Cytomegalovirus Immediate-Early Gene Product 2: A Novel Mechanism in Cytomegalovirus-Induced Apoptosis in Human Retina

Human CMV (HCMV) is an important pathogen that causes widespread diseases in immunocompromised individuals. Among the opportunistic HCMV infections, HCMV retinitis is most common in transplant recipients and AIDS patients. It often leads to blindness if left untreated. The question as to how HCMV infection causes retinal pathogenesis remains unresolved. Here, we report that viral immediate-early gene product 2 (IE2), but not IE1, up-regulates the Fas ligand (FasL) expression in HCMV-infected human retinal pigment epithelium cells. Increased secretion of FasL from virally infected cells into cultured medium was observed upon HCMV infection. The capability of such cell-free medium to induce apoptosis of Fas (CD95)-expressing Jurkat cells further implies that Fas-FasL interaction might mediate cell death in the lesion of HCMV retinitis. To support this idea, we observed augmented soluble FasL levels in vitreous from AIDS patients with HCMV retinitis as compared with that from AIDS patients without HCMV infection. In addition, by in situ hybridization and immunohistochemistry, we detected enhanced signals of FasL, the existence of viral IE Ags and apoptotic cells at the same sites in the lesion of HCMV-infected retina. These results strongly suggest that IE2 induction of FasL expression in human retina might be an important event that takes place in the early stage of infection and finally leads to visual loss in individuals affiliated with HCMV retinitis.

Soluble vascular endothelial growth factor receptor-1 protects mice in sepsis

Objective:To determine the putative role in the modulation of inflammation of a soluble form of Flt-1 (sFlt), a potent vascular endothelial growth factor antagonist, in experimental endotoxemia and sepsis. Design:Randomized prospective experimental study. Setting:University medical laboratory. Subjects:Male C56BL/6 strain mice. Interventions:We investigated the expression patterns and the effects of vascular endothelial growth factor and soluble Flt-1 in experimental endotoxic shock and sepsis. The possible anti-inflammatory mechanism of soluble Flt-1 was also evaluated. Measurements and Main Results:Both vascular endothelial growth factor and sFlt-1 were rapidly released from macrophages activated in vitro by lipopolysaccharide and in the plasma of endotoxemic mice. Administration of vascular endothelial growth factor enhanced proinflammatory cytokine production and mediated a dramatic increase in mortality in endotoxemic mice. Treatment with sFlt-1 attenuated inflammatory responses, inhibited recruitment of inflammatory cells into the peritoneal cavity, and improved survival in a lethal endotoxemia and cecal ligation and puncture-induced sepsis model, even when administered as late as 24 hrs after the onset of sepsis. Conclusions:These findings support a critical protective role of sFlt-1 in endotoxic shock and sepsis. sFlt-1 may therefore have utility as an adjunctive agent for the treatment of sepsis syndrome.

Evolution of the free groin flap: the superficial circumflex iliac artery perforator flap.

Background: The free groin flap, revolutionary in 1972, has gradually lost its relative popularity because of the new free flaps available as well as because of some of its inherent disadvantages, including a short arterial pedicle, variable arterial anatomy, the generally small caliber of the included blood vessels, its bulkiness, and numbness at the donor site. Methods: From December of 2002 to May of 2004, the authors successfully overcame a number of these disadvantages by means of clinical application of the superficial circumflex iliac artery perforator flap in 12 patients (age range, 15 to 67 years). These surgical procedures involved nine recipient sites in the upper limbs, two in the foot, and one in the buccal region. Results: This flap not only overcomes most of the disadvantages of the free groin flap but also demonstrates many of its advantages, including the following: (1) concealment of the donor-site scar; (2) primary closure of the donor site; (3) the availability of a large cutaneous flap (25 × 8 cm to 6 × 4 cm); (4) non–hair-bearing skin; (5) longer arterial pedicle (3 to 13 cm); (6) typically requiring no vessel grafting; (7) seldom being a “bulgy” flap; (8) smaller are of numbness at the donor site; and (9) less time required for flap dissection (0.5 to 1.5 hours). Conclusions: The superficial circumflex iliac artery perforator flap is an evolution of the conventional free groin flap. This flap not only overcomes most of the disadvantages of the free groin flap but also offers the many advantages of the successful application of the free groin flap.

Pulsatile ocular blood flow in asymmetric exudative age related macular degeneration

BACKGROUND/AIMS Decreased perfusion or increased vascular resistance of the choroidal vessels had been proposed as the vascular pathogenesis for age related macular degeneration (AMD). This study planned to answer the question whether pulsatile ocular blood flow (POBF) was different in patients with asymmetric exudative AMD between eyes with drusen, choroidal neovascularisation (CNV), or disciform scar. METHODS 37 patients with asymmetric exudative AMD were enrolled in this observational case series study. POBF were measured in both eyes of each subject. Eyes with high myopia, anisometropia, recent laser treatment, and glaucoma were excluded. RESULTS After adjusting for ocular perfusion pressure, intraocular pressure, and pulse rate, multivariate regression analysis with generalised estimating equation showed POBF was significantly higher in eyes with CNV (1217 (SD 476) μl/min) than the contralateral eyes with drusen (1028 (385) μl/min) (p = 0.024). Eyes with disciform scar had lower POBF than the contralateral eyes with drusen (999 (262) μl/min and 1278 (341) μl/min, respectively, p<0.001). There was no significant correlation between the POBF and the lesion size of the CNV. CONCLUSION The POBF in eyes with drusen was lower than their fellow eyes with CNV, but higher than their fellow eyes with disciform scar. This finding suggests that haemodynamic differences between fellow eyes in individuals are relevant to the development of CNV and the formation of disciform scar. Further studies on the follow up patients might shed light on the pathogenesis of exudative AMD.