Wide-range and area-selective threshold voltage tunability in ultrathin indium oxide transistors

The scaling of transistors with thinner channel thicknesses has led to a surge in research on two-dimensional (2D) and quasi-2D semiconductors. However, modulating the threshold voltage (VT) in ultrathin transistors is challenging, as traditional doping methods are not readily applicable. In this work, we introduce a optical-thermal method, combining ultraviolet (UV) illumination and oxygen annealing, to achieve broad-range VT tunability in ultrathin In2O3. This method can achieve both positive and negative VT tuning and is reversible. The modulation of sheet carrier density, which corresponds to VT shift, is comparable to that obtained using other doping and capacitive charging techniques in other ultrathin transistors, including 2D semiconductors. With the controllability of VT, we successfully demonstrate the realization of depletion-load inverter and multi-state logic devices, as well as wafer-scale VT modulation via an automated laser system, showcasing its potential for low-power circuit design and non-von Neumann computing applications.

A Versatile Method to Enhance the Operational Current of Air-Stable Organic Gas Sensor for Monitoring of Breath Ammonia in Hemodialysis Patients

Point-of-care (POC) application for monitoring of breath ammonia (BA) in hemodialysis (HD) patients has emerged as a promising noninvasive health monitoring approach. In this context, many organic gas sensors have been reported for BA detection. However, one of the major challenges for its integration with affordable household POC application is to achieve stable performance for accuracy and high operational current at low voltage for low-cost read-out circuitry. Herein, we exploited the stability of the Donor-Acceptor polymer on the cylindrical nanopore structure to realize the sensors with a high sensitivity and stability. Then, we proposed a double active layer (DL) strategy that exploits an ultrathin layer of Poly(3-hexylthiophene-2,5-diyl) (P3HT) to serve as a work function buffer to enhance the operational current. The DL sensor exhibits a sustainable enhanced operational current of microampere level and a stable sensing response even with the presence of P3HT layer. This effect is carefully examined with different aspects, including vertical composition profile of DL configuration, lifetime testing on different sensing layer, morphological analysis, and the versatility of the DL strategy. Finally, we utilize the DL sensor to conduct a tracing of BA concentration in two HD patients before and after HD, and correlate it with the blood urea nitrogen (BUN) levels. A good correlation coefficient of 0.96 is achieved. Moreover, the feasibility of DL sensor integrated into a low-cost circuitry was also verified. The results demonstrate the potential of this DL strategy to be used to integrate organic sensor for affordable household POC devices.

Long-term results of coronary artery bypass grafting in patients with dialysis-dependent renal failure

AIM

Coronary artery disease is the main cause of mortality and morbidity in dialysis-dependent renal failure patients. Both the prevalence and incidence of renal failure are high in Taiwan. However, there were few reports exploring the outcome of coronary aortic bypass grafting (CABG) in these patients. The aim of this study was to determine the survival outcome and risk factors for mortality from CABG in this population.

METHODS

The operative, early postoperative and late results of 170 dialysis patients undergoing isolated coronary artery bypass grafting from January, 2000 to January, 2012 were retrospectively reviewed. Operative mortality, long-term survival, and risk factors were analyzed.

RESULTS

One hundred and seventeen patients (68.8%) were male, and the mean age was 61.5±10.3 years (range, 34-86 years). Follow-up was 40.3±32.1 months. Operative mortality was 8.2%. Actuarial survival, including operative mortality, was 81±3% at 1 year, 68±4% at 3 years, 58±5% at 5 years and 49±6% at 10 years, better than the natural course of dialysis-dependent renal failure patients. Age, emergent operation, postoperative ventricular tachycardia or fibrillation, postoperative intra-aortic balloon pump insertion, gastrointestinal bleeding, and left internal mammary artery graft were significant predictors of operative or long term mortality. Most causes of late death were due to infection or cardiac events.

CONCLUSION

CABG in dialysis patients is associated with a higher incidence of complications, but has acceptable mortality. CABG is beneficial in this population. Internal mammary artery grafting may provide more favorable long term outcomes.

Aqueous extract of Anoectochilus formosanus attenuate hepatic fibrosis induced by carbon tetrachloride in rats

The aim of this study was to investigate the effects of aqueous extract of Anoectochilus formosanus (AFE) on liver fibrogenesis in carbon tetrachloride (CCl4)-induced cirrhosis. Fibrosis was induced in rats by oral administration of CCl4 (20%, 0.5 ml/rat, p.o.) twice a week for 8 weeks. AFE (0.5 and 2.0 g/kg, p.o., daily for 8 weeks) was administered to rats simultaneously. AFE showed reducing actions on the elevated levels of GOT and GPT caused by CCl4. Liver fibrosis in rats induced by CCl4 led to the drop of serum albumin concentration; the AFE increased the albumin concentration. The CCl4-induced liver fibrosis markedly caused liver atrophy and splenomegalia, while AFE increased the liver weight, and decreased the spleen weight. The CCl4-induced liver fibrosis decreased the protein content, and increased collagen contents in rat's liver. AFE significantly increased the contents of protein and reduced the amount of collagen in the liver. In CCl4-treated rats, glutathione concentrations of liver were not affected. AFE significantly increased liver glutathione concentrations. All these results clearly demonstrate that AFE can reduce the liver fibrogensis in rats induced by CCl4.

Growth inhibition of cultured smooth muscle cells by corrosion products of 316 L stainless steel wire

The potential cytotoxicity on vascular smooth muscle cells of corrosion products from 316 L stainless steel, one of most popular biomaterials of intravascular stents, has not been highlighted. In this investigation, 316 L stainless steel wires were corroded in Dulbecco's modified eagle's medium with applied constant electrochemical breakdown voltage, and the supernatant and precipitates of corrosion products were prepared as culture media. The effects of different concentrations of corrosion products on the growth of rat aortic smooth muscle cells were conducted with the [3H]-thymidine uptake test and cell cycle sorter. Both the supernatant and precipitates of corrosion products were toxic to the primary culture of smooth muscle cells. The growth inhibition was correlated well with the increased nickel ions in the corrosion products when nickel concentration was above 11.7 ppm. The corrosion products also changed cell morphology and induced cell necrosis. The cell growth inhibition occurred at the G0/G1 to S transition phase. Similar to our recent study of nitinol stent wire, the present investigation also demonstrated the cytotoxicity of corrosion products of 316 L stainless steel stent wire on smooth muscle cells, which might affect the poststenting vascular response.

Combined innominate artery reconstruction and coronary artery bypass grafting

Two patients having significant coronary artery disease with innominate artery near-total occlusion presented neurological deficit of syncope events or cerebellar and brain stem infarct. Both of them were successfully treated with one-stage reconstruction combined with aorto-carotid-subclavian bypass and coronary artery bypass grafting (CABG). While it could not be over-emphasized how to protect both myocardium and cerebrum during CABG, cerebral perfusion through the reconstructed carotid bypass graft is the key maneuver during cardiac arrest and moderate hypothermia. Hypoperfused cerebral hemispheres were both improved extensively in the follow-up angiography. The absence of cerebral deficit and the free from coronary angina suggested that surgical technique to combine innominate with coronary artery surgery is feasible with acceptable mortality and morbidity rate.

Endovascular aortic graft exclusion of abdominal aortic aneurysm

Endovascular repair of abdominal aortic aneurysms has evolved dramatically within the past few years. This study reports the first successful case in Taiwan area of infrarenal abdominal aortic aneurysm treated with endovascular aortic bifurcational stent-graft. Minimally invasive surgery leading to early recovery, mobilization and shortened hospital day was promising. In addition, there were no local, remote or systemic complications during a 18-month follow-up. Thus, the procedure is an attractive alternative in its potential to reduce morbidity and mortality associated with open surgical repair, especially for patients who are not surgical candidates because of comorbidities. Careful patient selection and more experiences with refined endograft models will elucidate the feasible alternative to conventional surgical repair.

Identification of a candidate human neurohematopoietic stem-cell population

It was recently reported that transplantation of clonally derived murine neurosphere cells into sublethally irradiated allogeneic hosts leads to a donor-derived hematopoietic reconstitution. The confirmation of the existence of a common neurohematopoietic stem cell in the human brain will have a significant effect on stem cell research and on clinical transplantation. Here, it is demonstrated that the human fetal brain contains separate but overlapping epidermal growth factor (EGF)-responsive and basic fibroblast growth factor (FGF-2)-responsive neural stem cells. The majority (> 85%) of cells within these EGF- and/or FGF-2-generated neurospheres express characteristic neural stem/progenitor cell markers including nestin, EGF receptor, and FGF-2 receptor. These neural stem cells can be continuously passaged in vitro, and demonstrate a constant 20-fold expansion in every passage for up to the fifth passage (the longest period that has been carried out in the authors' laboratory). These neural stem cells are multipotential for neurons, astrocytes, and oligodendrocytes. After transplantation into SCID-hu mice, all neural stem cells, regardless of passages, culture conditions, and donors, are able to establish long-term hematopoietic reconstitution in the presence of an intact human bone marrow microenvironment.

Ameliorative effects of Anoectochilus formosanus extract on osteopenia in ovariectomized rats

The purpose of this study was to determine ameliorative effects of crude aqueous extract of Anoectochilus formosanus (AFE) on osteopenia in ovariectomized (OVX) rats. First, all of the rats were divided into sham and OVX groups. The OVX rats were allowed to lose bone for 6 weeks. At 6 weeks post-OVX, the OVX rats were divided into four groups treated with water, 17beta-estradiol (30 microg/kg, daily s.c. injection) or AFE (0.5, 2 g/kg, daily, orally) for 12 weeks. In OVX rats, the increases of body weight and serum total cholesterol were significantly decreased by AFE or 17beta-estradiol treatment. In OVX rats, atrophy of uterus and vagina was preserved by treatment with 17beta-estradiol, but not by AFE. The decreased weight of pituitary was increased by treatment with both 17beta-estradiol and AFE. There were decreases in bone density and calcium content including the right femur and the fourth lumbar vertebra, when compared with the sham control rats. Treatment with either 17beta-estradiol or AFE ameliorated these changes induced by OVX. In addition, ovariectomy increased serum alkaline phosphatase levels. The increases were suppressed by the treatment with 17beta-estradiol and AFE. Our results demonstrated that AEF could ameliorate ovariectomy-induced osteopenia.

Inverted follicular keratosis

Inverted follicular keratosis (IFK) is a benign skin lesion that typically presents as an asymptomatic, solitary nodule on the face of middle-aged and older individuals. IFK may mimic malignant lesions, especially squamous cell carcinoma (SCC), both clinically and pathologically. We report a 35-year-old male patient who had an exophytic nodule with papillary surface on his right nasal ala of 3 months' duration. The nodule was solitary, flesh colored, 5 mm in diameter and tended to bleed. The patient received shave excision with cautery under the clinical impression of pyogenic granuloma. Pathologically, diagnostic confusion existed between IFK and SCC. Squamous eddy formation and lack of epithelial dysplasia were suggestive of IFK. The tissue was investigated for the presence of human papillomavirus (HPV) DNA sequences by polymerase chain reaction (PCR) and negative result was obtained. This patient healed satisfactorily after removal of the lesion and no visible recurrence occurred during the following 10 months. The possibility of histologically confusing IFK with SCC, leading to unwarranted disfiguring treatments of a benign lesion, is emphasized.

A salvianolic acid B-rich fraction of Salvia miltiorrhiza induces neointimal cell apoptosis in rabbit angioplasty model

Apoptosis has been suggested to participate in stabilizing cell number in restenosis. Salvia miltiorrhiza (SM) Bunge which is a Chinese herb widely used for the treatment of cardiovascular disorders contains a potent antioxidant, Salvianolic acid B. To determine whether the antioxidant affects vascular apoptosis, the present study examined the frequency of apoptotic cell death in atherosclerotic plaques and in restenotic lesions of cholesterol-fed rabbits. New Zealand White rabbits were treated with a normal diet (normal), a 2% cholesterol diet (HC), a 2% cholesterol diet and endothelial denudation (HC-ED), a 2% cholesterol diet with 5% water-soluble extract of SM (4.8 g/Kg B.W./day) and endothelial denudation (HC-ED-SM), or with a 2% cholesterol diet containing probucol (0.6 g/kg B.W./day) and endothelial denudation (HC-ED-probucol). Apoptosis and associated cell types were examined in serial paraffin sections by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and immunohistochemistry. The expression of p53, an apoptosis-related protein, was also examined. Apoptosis was mainly detected in the neointima of the three groups with endothelial denudation. The percentage of apoptotic cells in SM-treated group (68.5+/-5.9%) was significantly higher than that of normal (0%), HC (1.9+/-1.2%), HC-ED (46.1+/-5.4%), and probucol-treated (32.8+/-3.9%) groups. The SM treatment markedly reduced the thickness of the neointima which was mainly composed of smooth muscle cells with few macrophages. In accordance with the apoptotic cell counts, positive immunoreactivity for p53 was observed in restenotic lesions from HC-ED, SM-treated and probucol-treated groups but not in the intima of the other two groups. These results suggest that the treatment with salvianolic acid B-rich fraction of SM induces apoptosis in neointima which in turn may help prevent the neointimal thickening.

The cytotoxicity of corrosion products of nitinol stent wire on cultured smooth muscle cells

Although nitinol is one of most popular materials of intravascular stents, there are still few confirmative biocompatibility data available, especially in vascular smooth muscle cells. In this report, the nitinol wires were corroded in Dulbecco's modified Eagle's medium with constant electrochemical breakdown voltage and the supernatant and precipitates of corrosion products were prepared as culture media. The dose and time effects of different concentrations of corrosion products on the growth and morphology of smooth muscle cells were evaluated with [(3)H]-thymidine uptake ratio and cell cycle sorter. Both the supernatant and precipitate of the corrosive products of nitinol wire were toxic to the primary cultured rat aortic smooth muscle cells. The growth inhibition was correlated well with the increased concentrations of the corrosion products. Although small stimulation was found with released nickel concentration of 0.95 +/- 0.23 ppm, the growth inhibition became significant when the nickel concentration was above 9 ppm. The corrosion products also altered cell morphology, induced cell necrosis, and decreased cell numbers. The cell replication was inhibited at the G0-G1 to S transition phase. This was the first study to demonstrate the cytotoxicity of corrosion products of current nitinol stent wire on smooth muscle cells, which might affect the postimplantation neointimal hyperplasia and the patency rate of cardiovascular stents.

Increased corrosion resistance of stent materials by converting current surface film of polycrystalline oxide into amorphous oxide

Current efforts of new stent technology have been aimed largely at the improvement of intravascular stent biocompatibility. Among the chemical characteristics of metallic stents, surface oxide corrosion properties are paramount. Using our unique technique, the currently marketed 316 L stainless steel and nitinol stent wires covered with polycrystalline oxide were chemically etched and then passivated to form amorphous oxide. Excellent metallic-stent corrosion resistance with an amorphous oxide surface was demonstrated in our previous in vitro study. For in vivo validation, we compared the corrosion behavior of different oxide surfaces on various forms of test wires in the abdominal aorta of mongrel dogs using open-circuit potential and cyclic anodic polarization measurements. After conduction, the retrieved test wires were observed under scanning electron microscope. No passivity breakdown was found for wires covered with amorphous oxide, while wires with polycrystalline oxide showed breakdown at potentials between +0.2 to + 0.6 V. It has been proven that severe pitting or crevice corrosion occurred on the surface of polycrystalline oxide, while the surface of amorphous oxide was free of degradations in our experiment. We have demonstrated that this amorphous oxide coating on metallic material provides better corrosion resistance, not only in vitro but also in vivo, and it is superior not only in strength safety but also in medical device biocompatibility.

Ex vivo expansion of transplantable human hematopoietic stem cells: where do we stand in the year 2000?

Ex vivo expansion of hematopoietic precursors, progenitors and stem cells represents the modern era of cellular therapeutics in the 21st century. For the last 10 years, increasing means for identifying and purifying hematopoietic stem cells and cytokines have facilitated and improved the development of ex vivo stem cell expansion technology. However, technology has not yet reached a stage where ex vivo-expanded hematopoietic progenitors and stem cells can be used routinely for replacement therapy. Lessons learned over the past 10 years from investigations focused at developing optimal ex vivo stem cell expansion systems have continued to a much greater understanding of stem cell biology. This knowledge has led to novel attempts at ex vivo expansion of hematopoietic precursors, progenitors, and stem cells, and should facilitate development of a new generation of cellular therapeutics. This review addresses recent progress toward development of clinically useful protocols for stem cell expansion. In addition, we discuss the results of a limited number of clinical trials that address the efficacy of such procedures. Three major areas of ex vivo stem cell expansion that impact clinical feasibility are discussed, including: (1) selection of an optimal stem cell population for expansion, (2) definition of the desired characteristics of the expanded stem cell population to be used for engraftment, and (3) development of new reagents and procedures for expansion and infusion of hematopoietic progenitors and stem cells.

Transplantation and growth characteristics of human fetal lymph node in immunodeficient mice

OBJECTIVE

The lymph node is an integral component of the immune system and the major site of antigen-dependent lymphocyte proliferation and differentiation. Development of animal models possessing functional primary human lymph nodes will have a significant impact on research in lymphopoiesis and immune response. To date, successful transplantation of primary human lymph nodes in rodents has not yet been reported. This work was undertaken to develop a reliable methodology to engraft primary human fetal lymph nodes in immunodeficient mice.

MATERIALS AND METHODS

Three different sets of parameters, including three different transplantation sites in the mice, two different strains of immunodeficient mice, and two different preconditioning regimens, were evaluated. The growth characteristics of the implanted primary human fetal lymph nodes were examined 3 months after transplantation by histologic, immunocytochemical, and flow cytometric methods.

RESULTS

Transplantation of primary human fetal lymph nodes into subcutaneous pouches in the ears in severe combined immunodeficiency (SCID) mice preconditioned with etoposide reproducibly give rise to >80% engraftment. The engrafted primary human fetal lymph nodes undergo massive growth (>200-fold) and retain the same histology and cellular composition as fresh human fetal lymph nodes from the same donors.

CONCLUSIONS

We report, for the first time, the development of a reliable methodology to successfully engraft human fetal lymph node in SCID mice. The engrafted human lymph nodes are visible and accessible to experimental manipulations. This SCID-hu mouse model with human lymph node should provide a physiologically relevant system to investigate lymphopoiesis, immunologic response, and virus-mediated immunosuppression.

Harmonic analysis of DNA dynamics in a viscous medium

The harmonic dynamics of normal modes of double-stranded DNA in a viscous fluid are investigated. The model DNA consists of two backbone-supported DNA strands coiling around a common helix axis with base stacking, sugar puckering, interstrand hydrogen bonding, and intrastrand sugar-base interactions assigned values based on published data. Assuming that the DNA bases are shielded from direct bombardment by the solvent, analytical solutions are obtained. The dissipation and fluctuation of the normal modes of the bases moving along the spirals display the effect of the medium indirectly through interactions with the backbone. The dynamics of the backbone are found to be overdamped with the characteristic damping times extending to the picosecond region for disturbance in position and to the sub-picosecond region for disturbance in velocity. In addition to the dynamic mode of a rigid rod, the motions of the bases are coupled to the motions of the backbone with comparable amplitudes for disturbance in position. For disturbance in velocity, however, the bases are effectively at rest, not being able to follow the motions of the backbone. The angular frequencies of the underdamped vibrational modes, identified as the ringing modes of the bases with the backbone effectively at rest, are insensitive to the viscosity and lie in the low frequency region of the Raman spectrum. These findings indicate that the backbone of DNA plays a significant role in modulating the dynamics of double-stranded DNA in an overdamping environment. This modulation of the dynamics of the motions of the bases in DNA by environmental impediments to molecular motion is briefly discussed in connection with protein- and drug- DNA interactions as well as gene regulation.

Cryptococcal meningitis in non-HIV-infected patients

There are few reports on cryptococcal meningitis in non-HIV-infected patients in subtropical areas. We reviewed 94 non-HIV-infected patients microbiologically diagnosed with cryptococcal meningitis and hospitalized at National Taiwan University Hospital, 1977-1996. Forty-two patients (44.7%) had underlying diseases. The main initial manifestations were headache (86.2%), vomiting (72.3%) and fever (69. 1%). The 30 patients with T-cell suppression had more acute illnesses (median duration of symptoms: 14 days vs. 29 days), less typical presentations of meningitis, and reduced inflammatory responses compared with the 64 without T cell suppression. There was no statistical difference between patients who received amphotericin B treatment for 10 weeks and those received amphotericin B with subsequent fluconazole treatment, in terms of mortality rate and recurrence rate. Seventy-five patients (79.8%) had satisfactory clinical responses, and two relapsed. Eighteen patients died (19.1%) and 10 of these died within 2 weeks of hospitalization. Patients in this series had outcomes comparable with those from temperate and even tropical countries with high percentages of immunocompetent hosts. Factors significantly associated with death were lymphoma, semicoma, leukocytosis, and initial high titres of cryptococcal antigen in cerebral spinal fluid (especially >/=1 : 512). On multivariate analysis, lymphoma and initial high cryptococcal antigen titres were independent predictors of mortality.

A secreted and LIF-mediated stromal cell-derived activity that promotes ex vivo expansion of human hematopoietic stem cells

The development of culture systems that facilitate ex vivo maintenance and expansion of transplantable hematopoietic stem cells (HSCs) is vital to stem cell research. Establishment of such culture systems will have significant impact on ex vivo manipulation and expansion of transplantable stem cells in clinical applications such as gene therapy, tumor cell purging, and stem cell transplantation. We have recently developed a stromal-based culture system that facilitates ex vivo expansion of transplantable human HSCs. In this stromal-based culture system, 2 major contributors to the ex vivo stem cell expansion are the addition of leukemia inhibitory factor (LIF) and the AC6.21 stromal cells. Because the action of LIF is indirect and mediated by stromal cells, we hypothesized that LIF binds to the LIF receptor on AC6.21 stromal cells, leading to up-regulated production of stem cell expansion promoting factor (SCEPF) and/or down-regulated production of stem cell expansion inhibitory factor (SCEIF). Here we demonstrate a secreted SCEPF activity in the conditioned media of LIF-treated AC6.21 stromal cell cultures (SCM-LIF). The magnitude of ex vivo stem cell expansion depends on the concentration of the secreted SCEPF activity in the SCM-LIF. Furthermore, we have ruled out the contribution of 6 known early-acting cytokines, including interleukin-3, interleukin-6, granulocyte macrophage colony-stimulating factor, stem cell factor, flt3 ligand, and thrombopoietin, to this SCEPF activity. Although further studies are required to characterize this secreted SCEPF activity and to determine whether this secreted SCEPF activity is mediated by a single factor or by multiple growth factors, our results demonstrate that stromal cells are not required for this secreted SCEPF activity to facilitate ex vivo stem cell expansion. (Blood. 2000;95:1957-1966)

Clinical features and in vitro susceptibilities of two varieties of Cryptococcus neoformans in Taiwan

One hundred years after introduction of the Eucalyptus tree to Taiwan, a predominantly subtropical island, we analyzed clinical and microbiological data of 59 patients with Cryptococcus neoformans infection hospitalized at National Taiwan University Hospital during 1982 to 1997. There were 38 (64.4%) cases of cryptococcosis caused by the var. neoformans and 21 (35.6%) caused by the var. gattii. Thirty-three patients (55.9%) had impaired T cell function, which included 12 patients with acquired immunodeficiency syndrome (AIDS). Eleven of the 12 patients with AIDS were diagnosed after 1995, and 11 cases were caused by var. neoformans. Minimum inhibitory concentrations (MICs) determined by the NCCLS broth microdilution method using antibiotic medium 3 improved the discrimination of in vitro susceptibility against amphotericin B and demonstrated that var. gattii isolates were less susceptible (geometric means 0.25 microg/ml versus 0.64 microg/ml, P < 0.001). In addition, a higher proportion of var. gattii were less susceptible to flucytosine as compared with var. neoformans (35.0% versus 64.9%, P = 0.030). There was no seasonal clustering for isolation of var. neoformans, though infections caused by var. gattii peaked in July and August. Compared with the first study of cryptococcosis (1957-1972) at NTUH, this study demonstrated the increase in immunocompromised and elderly patients, as well as a higher proportion of Cryptococcus isolated from blood or bone marrow. Facing the increasing adaptive plantation of Eucalyptus in Taiwan, the importance of field study regarding the role of Eucalyptus plantations in Taiwan and occurrence of cryptococcosis in human beings cannot be over-emphasized.

Induction of peroxiredoxins in transplanted livers and demonstration of their in vitro cytoprotection activity

Peroxiredoxin (Prx)-I and -II belong to a new class of antioxidants. Here, we report that they are induced by ischemia/reperfusion (I/R) in transplanted livers. Hypothesizing that Prxs are induced to protect liver from oxidative damage, we transduced these human genes into murine NIH-3T3 cells. The overexpressed Prxs made the cells more resistant to t-butylhydroperoxide-induced apoptosis. These results indicate that Prx-I and Prx-II are induced by the transplantation process and can protect cells against oxidant damage in tissue culture. Thus, proper genetic manipulations of Prxs may be useful in increasing the success rate of organ transplantation.

Monoclonal anti-androgen receptor antibodies: production, characterization and potential diagnostic applications

Several monoclonal antibodies (mAbs) and novel mAb-based assays for the androgen receptors (AR) have been developed. Large amounts of the recombinant human AR protein produced by a baculovirus expression system were used as an antigen to produce mAbs. Twenty-nine AR-specific mAbs were first confirmed by Western blot analysis and were then characterized for their immunoglobulin isotypes, epitopes, and epitope localization in AR. Novel assays using flow cytometry and sandwich enzyme-linked immunosorbent assays (ELISA) were established to detect AR-expressing cells and to quantify soluble AR protein, respectively. Using immunostaining, we identified several anti-AR mAbs exclusively recognizing AR within the nuclei of the prostate cancer cell line LNCaP and of prostate tissues in both frozen and paraffin-embedded sections, whereas other mAbs could detect AR in both nuclear and cytoplasmic compartments. Interestingly, certain mAbs, such as G122-25 and G122-77, could distinguish the androgen-bound AR from the unoccupied AR. In sum, many purified AR protein and anti-AR mAbs, together with the assays developed, could be powerful tools for the study of functional AR and for the diagnosis of prostatic cancers.

Long-term ex vivo maintenance and expansion of transplantable human hematopoietic stem cells

We have developed a stromal-based in vitro culture system that facilitates ex vivo expansion of transplantable CD34(+) thy-1(+) cells using long-term hematopoietic reconstitution in severe combined immunodeficient-human (SCID-hu) mice as an in vivo assay for transplantable human hematopoietic stem cells (HSCs). The addition of leukemia inhibitory factor (LIF) to purified CD34(+) thy-1(+) cells on AC6.21 stroma, a murine bone marrow-derived stromal cell line, caused expansion of cells with CD34(+) thy-1(+) phenotype. Addition of other cytokines, including interleukin-3 (IL-3), IL-6, granulocyte-macrophage colony-stimulating factor, and stem cell factor, to LIF in the cultures caused a 150-fold expansion of cells retaining the CD34(+) thy-1(+) phenotype. The ex vivo-expanded CD34(+) thy-1(+) cells gave rise to multilineage differentiation, including myeloid, T, and B cells, when transplanted into SCID-hu mice. Both murine LIF (cannot bind to human LIF receptor) and human LIF caused expansion of human CD34(+) thy-1(+) cells in vitro, suggesting action through the murine stroma. Furthermore, another human HSC candidate, CD34(+) CD38(-) cells, shows a similar pattern of proliferative response. This suggests that ex vivo expansion of transplantable human stem cells under this in vitro culture system is a general phenomenon and not just specific for CD34(+) thy-1(+) cells.

Differential expression of peroxiredoxin subtypes in human brain cell types

The peroxiredoxin (Prx) protein is expressed widely in animal tissues and serves an antioxidant function associated with removal of cellular peroxides. We have cloned two Prx genes and observed differential expression of Prx-I and Prx-II (formerly NKEF-A and NKEF-B) in purified rat brain cell cultures (Sarafian et al. [1998] Mol. Chem. Neuropathol. 34:39-51). We have examined regional and cell-type-specific expression of Prx-I and Prx-II in paraffin sections of human brain using immunohistochemical methods. These studies revealed a clear segregation of expression of these two gene products in different brain cell types. In the cerebral cortex, cerebellum, basal ganglia, substantia nigra, and spinal cord, Prx-I was expressed primarily in astrocytes, while Prx-II was expressed exclusively in neurons. Prx-I was also prominently expressed in ependymal cells and subependymal matrix of substantia nigra and basal ganglia. Prx-II was not expressed at uniform density in all neurons. In general, small neurons such as cerebellar granule neurons displayed little or no staining, while large neurons, such as hippocampal pyramidal and Purkinje neurons were heavily stained. The absence of expression of Prx-I in neurons and the selective expression of Prx-II in large neurons suggest that these antioxidant enzymes serve distinct functional roles that may reflect the different functions and biochemical activities of these cell types. Restricted expression of these genes may also contribute to the selective vulnerability of these cells to a wide variety of neuropathologic conditions.

Diaschisis in chronic viral encephalitis with Koshevnikov syndrome

The authors report a 61-year-old man with chronic viral encephalitis and Koshevnikov syndrome occurring 42 months after initial symptom of right hemiparesis. Serial computed tomography of the brain showed changes in the attenuation of the left temporal lobe lesion over time. Magnetic resonance images of the brain showed enlargement of left temporoparietooccipital lobes with cortical gyral enhancement on T1-weighted images following intravenous administration of gadolinium-DTPA. 99mTc-HMPAO single-photon emission computerized tomography showed increased radioactivity and hyperperfusion in the left temporoparietal region with paradoxically decreased local tissue perfusion at the contralateral right hemisphere. Follow-up magnetic resonance images of the brain 4 years later showed atrophy of bilateral cerebral hemispheres. We postulate that a "transcallosal diaschisis" with subsequent degeneration is a possible mechanism. A brain biopsy from the left temporal lobe lesion showed pictures compatible with viral encephalitis probably herpes simplex encephalitis.

Sequential changes in heart rate variability after coronary artery bypass grafting

Heart rate variability (HRV) decreased soon after coronary artery bypass grafting and returned to the preoperative level within 2 months; however, HRV did not exceed the preoperative level, even 6 months after coronary artery bypass grafting. Although myocardial ischemia can be improved by coronary artery bypass grafting, HRV did not benefit from coronary artery bypass grafting within 6 months.

Minimally-invasive, direct coronary artery bypass grafting

BACKGROUND

Minimally-invasive, direct vision coronary artery bypass grafting (MIDCAB) is a new surgical technique performed via limited thoracotomy in a beating heart without cardiopulmonary bypass.

METHODS

From June 1996 to December 1996, MIDCAB was performed in 12 patients (all male, average age, 65.9 years). In 11 patients with left anterior descending coronary artery lesions, thoracotomy was performed via the left, fourth intercostal space and the pericardium was incised to identify the target site. About 8 cm of the left internal mammary artery was harvested. Bilateral anterolateral thoractomy was performed in one patient with left anterior descending and right coronary artery lesions. Anastomosis was performed under direct vision in the beating heart without cardiopulmonary bypass.

RESULTS

MIDCAB was performed successfully without morbidity. The patients' average stay in the intensive care unit was 1.8 days. No patient had any early cardiac event requiring additional surgery or percutaneous transluminal coronary angioplasty. Postoperatively, all patients were asymptomatic and their recovery was uneventful.

CONCLUSIONS

Our initial experience indicates that MIDCAB offers good results and is a treatment option for selected patients with left anterior descending and/or right coronary artery lesions.

Computed tomography in the determination of surgical emergency for symptomatic abdominal aortic aneurysm

BACKGROUND

What is the best surgical timing for symptomatic AAA? Surely, the answer depends on accurate and prompt diagnosis of 'rupture or not'. Abdominal CT is one of the reliable and familiar diagnostic tools. We will present our own CT classification method for symptomatic AAA which is used as the guideline for 'emergency or not'.

METHODS

From January 1989 to January 1995, 52 patients with symptomatic AAA received diagnostic CT scan for quick disease differentiation and determination of surgical emergency. The findings were classified into four categories. Category I included 26 patients with intact aorta; Category II included four patients with contained retroperitoneal abdominal aortic leakage; Category III included 14 patients with contained massive retroperitoneal hematoma; and Category IV included eight patients with retroperitoneal or intraperitoneal active bleeding.

RESULTS

Compared with the standard diagnosis of rupture via laparotomy, CT is an excellent tool, showing 88% sensitivity and 88% specificity. This is better than sonography, which has a high false-positive rate of 33% and low specificity of 62%. Hospital mortality was distinctive with 4.3% in Category I, none in Category II, 25% in Category III and 87.5% in Category IV.

CONCLUSIONS

In our experience, CT scan is a better diagnostic tool than sonography for symptomatic AAA. Even the delay imposed by obtaining a preoperative CT scan in patients with possible ruptured aneurysm does not adversely affect the patient's outcome. The information obtained significantly aids not only preoperative but also intraoperative management.

Surgical repair of Ebstein's anomaly

BACKGROUND

Ebstein's anomaly represents a congenital structural deformity of the tricuspid valve associated with a wide spectrum of morphologic and physiologic abnormalities. Valvuloplasty and tricuspid valve replacement are the main surgical treatments. Plication of the atrialized right ventricle and valvuloplasty of the tricuspid valve can achieve satisfactory clinical results. Two surgical techniques, known as Danielson's and Quaegebeur's methods, are often used clinically. This study was conducted to compare the postoperative results between both methods in treatment of Ebstein's anomaly.

METHODS

Valvuloplasty of tricuspid valve and the plication of atrialized right ventricle were performed in 8 out of 17 patients with Ebstein's anomaly in our hospital from January 1986 to August 1996. Danielson's method was used in six of eight patients, and Quaegebeur's method was used in the remaining two patients. There were three males and five females, aged from 8 months to 61 years (mean: 14.1 years).

RESULTS

All patients achieved clinical improvement in cardiothoracic ratio and heart functional class. Cardiac arrhythmia was the likely cause of death in two patients treated by Danielson's method, and one patient developed complete atrioventricular (A-V) block postoperatively. By Quaegebeur's method, all patients survived, but a permanent pacemaker was implanted for both patients due to their preoperative complete A-V block.

CONCLUSIONS

Both methods achieved satisfactory postoperative results. However, Quaegebeur's method seems to be more effective because it provided a simultaneous reconstruction of both tricuspid valve and right ventricle without the need for additional excision of the right atrium.

Evaluation of an epoxy-fixed biological patch with ionically bound heparin as a pericardial substitute

In an attempt to develop an improved pericardial substitute, we undertook the development of an epoxy-fixed biological patch with ionically bound heparin. The study was to evaluate the cross-linking characteristics of this newly developed biological patch using its glutaraldehyde-fixed counterpart as a control. In addition, the feasibility of using this newly developed biological patch as a pericardial substitute was assessed in a canine model. In the study, it was observed that the epoxy-fixed biological patch appeared more similar to the native pericardium in colour and was more pliable than its glutaraldehyde-fixed counterpart. Also, both the epoxy- and glutaraldehyde-fixed biological patches had significant increases in fixation index and denaturation temperature as compared to the fresh one (p < 0.05). In the canine study, the epoxy-fixed biological patch with ionically bound heparin was found to have significantly less adhesion formation than those currently used clinically (p < 0.05).

Bacteremia due to Citrobacter species: significance of primary intraabdominal infection

From 1982 to 1994, 45 patients (1.22 episodes per 10,000 discharged patients) were treated for citrobacter bacteremia at National Taiwan University Hospital (Taipei). All patients had at least one underlying disease. Citrobacter bacteremia most commonly occurred in patients with malignancies (48.9%) or hepatobiliary stones (22.2%). Intraabdominal tumors comprised the majority (59.1%) of malignancies. Bacteremia commonly originated from sites such as the abdominal cavity (51.1%), urinary tract (20%), and lung (11.1%). Polymicrobial bacteremia was diagnosed in 15 patients (33.3%); for nine (60%) of these patients, the source of the infection was intraabdominal. Prior treatment with a third-generation cephalosporin was significantly associated (P < .01) with the development of multidrug resistance among the isolates. The mortality associated with citrobacter bacteremia was 17.8%. Poor prognostic factors included pneumonia, altered mental status on presentation, hypothermia, oliguria, septic shock, deterioration in mental status, hyperbilirubinemia, azotemia, and thrombocytopenia. Combination therapy, as compared with other regimens, improved the outcome of citrobacter bacteremia.

Acute diffuse phlegmonous esophagogastritis: report of a survived case

A 42-year-old man was admitted because of a persistent pain on swallowing together with epigastralgia, chest pain, fever, and shortness of breath for 5 days. An unbearable shortness of breath with a retrosternal pain was noted each time he tried to lie down. The patient also developed bilateral pleural effusion and pericardial effusion. Ten days after admission, he underwent an emergency laparotomy after an acute episode of severe epigastralgia with hematemesis and rebound tenderness limited to the epigastrium. Operative findings showed diffuse phlegmonous esophagogastritis. A near-total esophagectomy and a total gastrectomy were done. He lost 15 kilograms of body weight and was discharged 3 months later. The patient underwent reconstructive surgery 2 months after discharge, recovered well and regained his weight within one year.

Suppression of glioblastoma angiogenicity and tumorigenicity by inhibition of endogenous expression of vascular endothelial growth factor

The development of new capillary networks from the normal microvasculature of the host appears to be required for growth of solid tumors. Tumor cells influence this process by producing both inhibitors and positive effectors of angiogenesis. Among the latter, the vascular endothelial growth factor (VEGF) has assumed prime candidacy as a major positive physiological effector. Here, we have directly tested this hypothesis in the brain tumor, glioblastoma multiforme, one of the most highly vascularized human cancers. We introduced an antisense VEGF expression construct into glioblastoma cells and found that (i) VEGF mRNA and protein levels were markedly reduced, (ii) the modified cells did not secrete sufficient factors so as to be chemoattractive for primary human microvascular endothelial cells, (iii) the modified cells were not able to sustain tumor growth in immunodeficient animals, and (iv) the density of in vivo blood vessel formation was reduced in direct relation to the reduction of VEGF secretion and tumor formation. Moreover, revertant cells that recovered the ability to secrete VEGF regained each of these tumorigenic properties. These results suggest that VEGF plays a major angiogenic role in glioblastoma.

Cross-linking characteristics of biological tissues fixed with monofunctional or multifunctional epoxy compounds

The cross-linking characteristics of biological tissues fixed by various epoxy compounds with different chemical structures (i.e. number of epoxide functional groups and backbone length) were investigated. Generally speaking, the tissues fixed with monofunctional fixatives were more pliable than those fixed with multifunctional fixatives. The fixation indices of the fixed tissues did not seem to be affected by the chemical structures of the fixatives. However, the number of functional groups and backbone length of the fixatives did play an important role in influencing the denaturation temperatures of the fixed tissues. In general, the denaturation temperatures of the multifunctional fixed tissues were higher than those of the monofunctional fixed tissues. Among the monofunctional fixed tissues, it was found that increasing the backbone length of the fixative decreased the denaturation temperature of the fixed tissue. This effect was present until the backbone length of the fixative became large enough.

Role of platelet-endothelial cell adhesion molecule (PECAM) in platelet adhesion/aggregation over injured but not denuded endothelium in vivo and ex vivo

BACKGROUND AND PURPOSE

We previously demonstrated that a monoclonal antibody (MoAb) with anti-CD31, anti-platelet-endothelial cell adhesion molecule (PECAM)-like properties delayed platelet adhesion/aggregation at a site of minor endothelial injury. To our knowledge, this was the first in vivo demonstration of an effect of anti-CD31. There was no exposure of collagen or basal lamina at the injured site, and the modulation of adhesion/aggregation at such sites has not received much study. The present investigation attempted to replicate the first with the use of a different MoAb, definitely characterized as anti-PECAM. In addition, an ex vivo investigation was performed to see whether the in vivo action of anti-PECAM could have been caused by an effect of the MoAb on the platelets rather than on the endothelium.

METHODS

A helium-neon laser, in the presence of intravascular Evans blue, was used to injure the endothelium of arterioles on the surface of the mouse brain. Intravital microscopy was used to determine the number of seconds required for the light to initiate the first recognizable platelet aggregate forming at the injured site. Mice injected with vehicle were compared with mice injected with 2 mg/kg anti-PECAM through the tail vein. The injection was 10 minutes before challenge with the laser. Additional studies were performed of aggregation produced in vitro by arachidonate and by ADP added to platelet-rich plasma (PRP) prepared from blood taken from MoAb-treated and vehicle-treated mice.

RESULTS

Aggregation latency was significantly prolonged (P<.02) by anti-PECAM (121+/-59 versus 65+/-26 seconds in controls; n=10 each). Aggregation ex vivo was not affected.

CONCLUSIONS

PECAM is an important modulator of platelet adhesion/aggregation at sites of minor endothelial damage in brain arterioles. The data are consistent with the hypothesis that PECAM sites on the endothelium are involved and may be exposed by the injury to promote adhesion/aggregation. Since the endothelial cell layer is intact at these sites, mechanisms such as this offer important alternatives to the more commonly studied pathways of platelet activation, which require exposure of collagen and are not applicable in this model.

MRI appearance of spinal lesions: metastatic tumors or infections?

Three patients with pathologically verified spinal osteomyelitis and another three with metastatic tumors of the spine were investigated. MRI of th spine of four patients showed several unusual findings. The preservation of intervertebral discs and endplates did not predict accurately the diagnosis of either infections or tumors. The "pepper and salt" appearing feature may also occur in a metastatic tumor. Plain radiographs, CT, and radioisotope bone scans were less sensitive than MRI to disclose the lesions. In cases of osteomyelitis, the systemic sources of infections were frequently not found, and the responsible microorganisms could not be identified even from the surgical specimens of two patients. However, mycobacterium tuberculosis was found in the surgical specimen of a patient with cervical spinal lesion whose MRI was indistinguishable from a metastatic tumor. Surgicopathological diagnosis was therefore crucial and mandatory in these instances.

Computed tomography and magnetic resonance imaging of diffuse pigmented villonodular synovitis: report of a case

We describe the computed tomographic (CT) and magnetic resonance imaging (MRI) features of a surgically proven case of diffuse pigmented villonodular synovitis (PVNS) of the knee in a 34-year-old woman. A complex mass consisting of solid and multicystic components was clearly demonstrated by CT and MRI. The solid part showed homogeneous hypodense attenuation relative to adjacent muscles on CT scans, but it showed inhomogeneous signal intensity on spin echo T1- and T2-weighted images (WI). The solid component enhanced homogeneously on CT scans but heterogeneously on MR images. Multiseptated enhancement of the cystic component on both CT and MR images were displayed. All of the above features were better demonstrated on MRI. Multiple marked hypointense round and patchy areas, and also a few areas isointense to subcutaneous fat within the lesion were also found on T1WI, proton density WI and T2WI. These characteristic MRI features of PVNS correlated well with its histologic structures: depositions of hemosiderin and fat in the proliferative synovial villi and bloody cystic content. These features may help to distinguish PVNS from other disease entities arising from the synovium.

Optical interpretation of a complex-order Fourier transform

It is demonstrated that the definition of a fractional-order Fourier transform can be extended into the complexorder regime. A complex-order Fourier transform deals with the imaginary part as well as the real part of the exponential function in the integral. As a result, while the optical implementation of fractional-order Fourier transform involves gradient-index media or spherical lenses, the optical interpretation of complex-order Fourier transform is practically based on the convolution operation and Gaussian apertures. The beam width of a Gaussian beam subjected to the complex-order Fourier transform is obtained analytically with the ABCD matrix approach.

The expression of prostatic acid phosphatase is transcriptionally regulated in human prostate carcinoma cells

The expression of prostatic acid phosphatase (PAcP) in three human prostate carcinoma cell lines including LNCaP, DU 145 and PC-3, was studied to explore its potential role as a marker in the progression of prostate cancer. Although Southern blot analysis suggested the presence of PAcP gene in all three prostate carcinoma cell lines, the Northern blot analysis and the reverse transcriptase-polymerase chain reaction (RT-PCR) assay showed that PAcP mRNA can be detected only in LNCaP cells. As one of the major differences between LNCaP cells and PC-3 as well as DU 145 cells is the androgen-sensitivity of LNCaP cells, we then focused on the influence of PAcP expression by the presence of androgen receptor (AR) in human AR cDNA-transfected PC-3 cells and high passages of LNCaP cells. The results demonstrated that the transfection of human AR cDNA into PC-3 cells did not have any detectable effect on the expression of PAcP. Further, in LNCaP cells, while the level of PAcP mRNA diminished upon passage, the AR mRNA level remained approximately the same. Together, these data suggested that the differential expression of PAcP in different prostate carcinoma cells including high passages of LNCaP cells may occur at the transcriptional level and may have little linkage to the expression of AR.

Characterization of human androgen receptor overexpressed in the baculovirus system

An essential step in the process of understanding the structure and function of the human androgen receptor (hAR) involves the production of large quantities of the hAR. For this purpose, the full-length hAR has been overproduced in insect cells by using a baculovirus genetic expression system. The recombinant hAR is produced in Sf21 insect cells at approximately 7 pmol/mg of protein (1 x 10(6) AR molecules per cell), which is 70-150 times greater than levels detected in androgen target tissues. Androgen can bind to the baculovirus-expressed hAR with high affinity (Kd = 0.46 nM), and the specificity of hormone binding in baculovirus-expressed hAR is essentially identical to that of bona fide hAR. An anti-AR monoclonal antibody can recognize the baculovirus-expressed hAR at approximately 100 kDa upon Western blot analysis. Sucrose gradient analysis shows that baculovirus-expressed hAR complexes sediment at 4 S in a high salt medium and these complexes can interact with anti-AR monoclonal antibody to form complexes that sediment at 8-10 S. Therefore, production of recombinant hAR from the baculovirus expression system will provide an alternative source of biologically active hAR for studies on the molecular mechanisms of androgen action.

Studies on the arrangement of glucocorticoid receptors in the plasma membrane of S-49 lymphoma cells

The presence of glucocorticoid receptors is required for glucocorticoid-mediated lymphocytolysis to take place. However, the explicit mechanism of involvement of this receptor continues to be debated. We have recently presented evidence that this response is mediated by a specialized form of the glucocorticoid receptor that resides in the plasma membrane (mGR). Using sequential cell separation techniques ("immunopanning," fluorescent cell sorting, and soft agar cloning), a resultant population of membrane receptor-enriched cells have remained stable and provided material for further analysis. The mGR patching and capping phenomenon originally observed with fluoresceinated monoclonal antibody techniques was verified here with electron micrographic analysis using colloidal gold-conjugated antibody. Using 3H-labeled monoclonal antibody, a radioimmunoassay for membrane receptors was developed. Trypsin treatment removed the membrane receptor antigenic site from the surface of cells. Peptide mapping of receptor purified from plasma membranes reveals several trypsin and alpha-chymotrypsin cleavage sites. Larger fragments resulted from cleavage of the membrane receptor of cells enriched for mGR versus those found in cells depleted of the membrane form, although most of the resulting fragments are shared by the two forms. Confirmation of previous studies correlating membrane receptor with the mechanism of glucocorticoid sensitivity is now extended to include elimination of the lymphocytolysis effect in membrane receptor-stripped (trypsinized) S-49 cells.