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| 2. |
- Li, K., et al.
(författare)
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MBE-based SiGe/Si heterojunction multilayer structures
- 2001
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 227-228, s. 744-748
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, SiGe/Si multilayer heterostructures prepared by molecular beam epitaxy (MBE) are described with the aim of manufacturing SiGe heterojunction bipolar transistors (HBTs). Based on the simulations made by Medici, device structures have been designed and grown. The quality of the MBE layered structures has been characterized by reflection high-energy electron diffraction, X-ray diffraction, secondary ion mass spectrometry and spreading resistance. Furthermore, SiGe-HBTs have been fabricated. Promising DC and RF results of processed HBT devices have been obtained. © 2001 Elsevier Science B.V.
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| 3. |
- Månsson, Peter, et al.
(författare)
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Anastomotic healing in the rat colon: comparison between a radiological method, breaking strength and bursting pressure.
- 2002
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Ingår i: International Journal of Colorectal Disease. - : Springer Science and Business Media LLC. - 1432-1262 .- 0179-1958. ; 17:6, s. 420-425
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: While mechanical parameters (breaking strength, bursting pressure) are used to measure colonic anastomotic healing, reported values are inconsistent. This study developed a novel approach to study colonic anastomotic repair and compared it with mechanical methods. Methods and materials: We created standardized four- and eight-suture colonic anastomoses and performed contrast enemas in rats. Results: All eight-suture anastomoses were tight at completion. In contrast, all four-suture anastomoses leaked immediately after the operation, but the integrity increased progressively, and at 12 h all were closed. No changes in breaking strength were observed up to 3 days postoperatively, in contrast to anastomotic bursting pressure which increased progressively over the same period. Integrity and bursting pressure increased in parallel to the anastomotic content of myeloperoxidase (MPO), indicating that neutrophil infiltration is not detrimental in normal healing. Moreover, local irradiation, which enhanced MPO activity, did not increase leakage, suggesting that neutrophil accumulation per se has no effect on the integrity of colonic anastomosis. In addition, administration of 5-fluorouracil, which decreased anastomotic MPO levels, increased anastomotic leakage. Conclusion: We present a novel approach to study anastomotic healing using radiological examination. While bursting pressure appears to be suitable for measuring early anastomotic healing in the colon, we demonstrate that breaking strength is not sufficiently sensitive to be used in examination of early healing. Moreover, our data suggest that the acute inflammatory response and associated neutrophil recruitment in the anastomosis does not negatively affect healing in the rat colon.
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| 4. |
- Saha, B., et al.
(författare)
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LEA-135 expression: its association with a lower risk of recurrence and increased overall survival of patients with lymph node-positive primary invasive breast cancer
- 2004
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Ingår i: Anticancer Res. - 0250-7005. ; 24:4, s. 2391-2400
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Tidskriftsartikel (refereegranskat)abstract
- A retrospective study was undertaken to determine and compare the prognostic significance of LEA-135 protein expression by immunohistochemistry with other prognostic pathological parameters, with respect to recurrence and overall survival. This study was conducted in freshly-frozen tissue sections from a cohort of 367 patients having primary invasive breast cancer, with axillary lymph node metastasis. The association of LEA-135 expression was compared with estrogen and progesterone receptor status, segmentectomy or radical mastectomy and hormonal therapy or chemotherapy in terms of recurrence or disease-free survival. Pathologic parameters including tumor size, histological tumor type and histological grade, as well as age of patients at the time of initial diagnosis, and the treatments, together with a median follow-up of 8.8 years were contemplated for the study. Among these parameters, tumor size and histological grade were individually and significantly associated with an increased probability of recurrence (log rank p<0.001 in both cases) and short survival (log ranks p<0.001 and p=0.002, respectively), whereas age was only significantly associated with an increased probability of recurrence (log rank p=0.002) by univariate analysis. By multivariate analysis, both tumor size and histological grade remained statistically significant for recurrence (log rank p<0.001 and p=0.013, respectively) and overall survival (log ranks p<0.001 and p=0.016, respectively). Among the prognostic biomarkers, both ER and PR expression were associated with a decreased rate of recurrence (log ranks p<0.001 and p=0.008, respectively) and overall survival (log ranks p<0.001 and p=0.002, respectively) by univariate analysis. By multivariate analysis, only the ER expression remained significantly associated with a decreased recurrence and increased overall survival (log ranks p=0.023 and p=0.002, respectively). Patients with high (>50% positive cells) or moderate (5-50% positive cells) number of LEA-135-positive cells had a lower probability (46%) of recurrence at 10 years after surgery compared to 76% in LEA-135-negative patients (log rank p<0.001) by univariate analysis. Moreover, the probability of overall survival was higher in patients with high or moderate expression of LEA-135 (46% and 47%, respectively) compared to LEA-135-negative patients (24%) by univariate analysis (log rank p=0.009). By multivariate analysis, the association remained statistically significant for recurrence (log rank p<0.001) and survival (log rank p=0.002). However, there was no significant association between LEA-135 and any of the pathological parameters, age, hormone receptor status, the mode of surgery or the form of therapy (chemo- and/or hormonal) received by this cohort of patients. The results show that an improved prognosis was directly associated with the density of LEA-135-positive cancer cells, while loss of LEA-135 expression was associated with an aggressive phenotype of cancer cells during breast cancer progression. Thus, LEA-135 expression can be implicated as a significant and independent biomarker to identify and distinguish high- from low-risk patients with lymph node-positive invasive breast cancer for an aggressive treatment. Moreover, according to the present results, LEA-135 expression appears to be associated with the tumor cells that have retained certain normal biological characteristics, leading to their lack of aggressiveness and hence a better prognosis.
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| 6. |
- Zhang, Shunli, et al.
(författare)
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End-of-life electric and electronic equipment management towards the 21st century
- 2000
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Ingår i: Waste Management & Research. - : Wiley. - 0734-242X .- 1096-3669 .- 1399-3070. ; 18:1, s. 73-85
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Tidskriftsartikel (refereegranskat)abstract
- With the rapid growth of the electronics industry and an evergrowing environmental awareness worldwide, an environmentally sound and economically viable management system for endoflife (EOL) electric and electronic equipment (EEE) is of great importance for sustainable development. Traditional recycling and processing of EOL electronics directed towards the recovery of copper and precious metals, will be faced with many challenges in the future. It has been recognized by the EOL EEE recycling industry that a new strategy for EOL EEE must be developed. In this paper, current status and future trends in EOL EEE management are presented. Selective dismantling of valuable and hazardous components is evaluated in terms of a graderecovery (GR) concept. It is concluded that selective dismantling and mechanical processing must be coordinated in such a way as to produce suitable materials for subsequent handling at the lowest cost. Furthermore, new developments in mechanical and thermal processing of EOL EEE are also discussed, which involve water table and eddy current separation techniques and reduction of dioxins and furans during combustion of the plastics containing halogenated flame retardants. In addition, the challenges and perspectives associated with EOL management of plastics and cathode ray tubes (CRTs) encountered in EOL EEE are highlighted in this paper. It is predicted that EEE, being designed for recycling in the 21st century, will be processed and recycled economically and ecologically on becoming obsolete.
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| 7. |
- Zhang, Wei
(författare)
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Studies on proteins involved in the molecular regulation of insulin exocytosis
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 2 diabetes mellitus is a disease characterized by impaired insulin secretion and insulin resistance. Better understanding of molecular mechanisms of insulin secretion may help to optimize type 2 diabetes management. The present work has thus investigated the expression of exocytotic proteins in insulin-producing beta-cells and their regulatory roles in insulin exocytosis. Western blotting and immunofluorescence histochemistry revealed that the syntaxin-interacting protein, mammalian homologue of C. elegans unc-18 gene (Munc-18), was expressed in insulin-secreting beta-cells. Munc-18 was present in both cytosol- and membrane-enriched fractions and was associated with syntaxin 1 in HIT-T15 cells. Administration of Munc-18 peptide or Munc-18 antiserum to permeabilized HIT-T15 cells increased insulin release, but had no effect on voltage-dependent Ca2+ channel activity. The data indicate that Munc-18 is a regulator of the insulin secretory machinery via a mechanism not involving syntaxin-associated Ca2+ channels. Tomosyn, another syntaxin-interacting protein, was also identified in pancreatic beta-cells. RT-PCR revealed that mRNAs for all three so far identified tomosyn isoforms were expressed in RINm5F cells and rat pancreatic islets. Overexpression of tomosyn in mouse beta-cells significantly decreased exocytosis as measured by changes in membrane capacitance using the patch-clamp technique, indicating an essential role of tomosyn in insulin secretion. The Munc-18-interacting protein Mint1 was demonstrated in beta-cells by immunohistochemistry and Western blotting. RT-PCR showed the expression of amplified PCR products corresponding to Mint1, Mint2 and Mint3 in RINm5F cells and rat islets. Immunohistochemistry with double-labeling revealed that Mint1 immunoreactivity was colocalized with Munc-18 in rat pancreatic islet cells. Mint1 immunoreactivity was preferentially distributed in the periphery of the cells, whereas Munc-18 immunoreactivity was mainly punctate in the cytosol. The presence of Mint in insulin-secreting beta-cells and the colocalization of Mint1 with Munc-18 suggest a functional role for Mint in the regulation of insulin secretion. Exocytosis of insulin-containing secretory granules depends on phosphatidylinositol (PI) 4-kinase activity, since inhibition of this enzyme suppressed glucose-stimulated insulin secretion. Intracellular application of PI 4-phosphate (PI(4)P) and PI 4,5-biphosphates (PI(4,5)P2) stimulated exocytosis by promoting the priming of secretory granules for release and increasing the number of granules in a readily releasable pool. Reducing cytoplasmic ADP concentration, which mimicks the effects of glucose stimulation, activated PI 4-kinase and increased exocytosis, whereas changes of the ATP-concentration in the physiological range had little effect. The PI(4,5)P2-binding protein, Ca2+-dependent activator protein for secretion (CAPS), was present in beta-cells and neutralization of the protein abolished both Ca2+- and PI(4,5)P2-induced exocytosis. We conclude that ADP-induced changes in PI 4-kinase activity, via generation of PI(4,5)P2 represents a metabolic sensor in the beta-cell by virtue of its capacity to regulate the release competence of the secretory granules. In type 2 diabetic Goto-Kakizaki (GK) rats, the pancreatic islets frequently showed an irregular structure with cells separated from each other. The immunoreactivities for vesicle-associated membrane protein-2 (VAMP-2), synaptotagmin III, cysteine string protein (CSP), Munc-18, tomosyn, N-ethylmaleimide-sensitive factor (NSF), alpha-soluble NSF attachment protein (alpha-SNAP), synaptosomal-associated protein of 25 kDa (SNAP-25) and syntaxin in pancreatic islets of GK rats were weaker. Insulin immunoreactivity was also decreased in GK rat beta-cells, whereas no detectable alteration in the actin immunoreactivity was shown. The data suggest that reduced expression of exocytotic proteins and decreased insulin content may contribute to the diabetic syndrome of GK rats. Taken together, we have demonstrated the presence of Munc-18, tomosyn, Mint and CAPS in beta-cells. Munc-18 and tomosyn are associated with syntaxin and are involved in the regulation of insulin secretion from beta-cells. CAPS is essential for insulin secretion and functions downstream of PI(4,5)P2. PI 4-kinase serves as a metabolic sensor of beta-cells and regulates priming of secretory granules via generation of PI(4,5)P2. In pancreatic islets of type 2 diabetic GK rats, the immunoreactivities for exocytotic proteins and insulin are decreased, which may be associated with impaired insulin secretion and the diabetic syndrome present in GK rats.
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| 8. |
- Zhang, Xiao Wei
(författare)
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Role of adhesion molecules and chemokines in TNF-alpha-induced leukocyte recruitment
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Migration of leukocytes from the circulating blood into the extravascular tissue is a key component in inflammatory reactions. Leukocyte extravasation (rolling-activation-adhesion-transmigration) is strictly coordinated by adhesion molecules and chemokines expressed on cell surfaces and in tissues. Tumor necrosis factor-alpha (TNF-alpha) is pleiotrophic cytokine, which plays an important role in the pathophysiology of numerous clinical conditions, including sepsis, rheumatic arthritis and inflammatory bowel diseases. The purpose of this study was to define adhesive pathways and chemokine networks regulating TNF-alpha-induced leukocyte recruitment in vivo. It was found that TNF-alpha-induced leukocyte rolling was mainly mediated by P-selectin. This P-selectin-supported rolling was found to be a precondition for the subsequent firm adhesion and tissue accumulation of leukocytes in response to TNF-alpha. Moreover, by use gene-deficient mice, it was observed that CD18 (Beta2-integrins) is dominating adhesion molecule on leukocytes mediating TNF-alpha-induced leukocyte adhesion. Moreover, it was found that the CXC chemokines, MIP-2 and KC, induced all steps in the extravasation process of leukocytes. In fact, CXC chemokine-induced leukocyte rolling was exclusively dependent on P-selectin, an event, which also was a prerequisite for later firm adhesion and transmigration. CXCR2, which the main receptor for MIP-2 and KC, was not expressed on endothelial cells, suggesting that an intermediary cell(s) mediates CXC chemokine upregulation of P-selectin. TNF-alpha increased gene expression of both MIP-2 and KC. However, no synergistic interaction between MIP-2 and KC was found and immunoneutralization of either MIP-2 or KC had no effect on TNF-alpha-provoked leukocyte responses. On the other hand, inhibition of both MIP-2 and KC markedly reduced tissue migration of leukocyte in response to TNF-alpha. The immunomodulator Linomide was found to inhibit TNF-alpha-induced leukocyte adhesion and accumulation. Taken together, this study demonstrates that leukocyte rolling supported by P-selectin is a common and final pathway for cytokine- and chemokine-induced leukocyte recruitment. Moreover, our data suggest that CXC chemokines are functionally redundant in TNF-alpha-induced accumulation of leukocytes.
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