Fast in situ generated ɛ-polylysine-poly (ethylene glycol) hydrogels as tissue adhesives and hemostatic materials using an enzyme-catalyzed method.

In this study, novel bio-inspired in situ hydrogels as tissue adhesives and hemostatic materials were designed and prepared based on ɛ-polylysine-grafted poly(ethylene glycol) and tyramine via enzymatic cross-linking. The enzymatic cross-linked method enabled fast gelation within seconds, which facilitated its therapeutic applications. By changing the cross-linking conditions, the storage modulus of the hydrogels could be tunable and the mechanical strength influenced the tissue adhesiveness of the hydrogels. Besides, the hydrogels showed fine network structures with appropriate pore sizes, which were thought to be a contributing factor to the strong adhesiveness. Benefiting from the strong mechanical properties and fine network structures, the ɛ-polylysine-grafted poly(ethylene glycol) and tyramine hydrogels exhibited superior wound-healing and hemostatic ability compared to conventional and commercially available medical materials. Moreover, indirect cytotoxicity assessment indicated that the ɛ-polylysine-grafted poly(ethylene glycol) and tyramine hydrogels were nontoxic to the L929 cell. These results demonstrated that the enzymatic cross-linked in situ ɛ-polylysine hydrogels hold high potential for tissue sealants and hemostatic materials.

Overexpression of NUAK1 is associated with disease-free survival and overall survival in patients with gastric cancer.

Novel (nua) kinase family 1 (NUAK1) is a member of the human adenosine monophosphate-activated protein kinases family, which is overexpressed in multiple human malignancies and thought to be involved in tumor invasion and metastasis ability. Our study is to investigate the association of NUAK1 expression with clinicopathological parameters and prognostic significance of patients with gastric cancer. The expression patterns of the NUAK1 protein in 117 primary archival gastric cancer specimens and 46 adjacent normal epithelial tissues from patients were detected by immunohistochemistry assay. Staining evaluation results were analyzed statistically in relation to various clinicopathological characters, recurrence-free survival and overall survival. High level of NUAK1 expression was detected in gastric cancer, significantly more than in adjacent normal epithelial cells. In gastric cancer, NUAK1 was positively correlated with depth of invasion, lymph node metastasis, pathological stage, surgical resection and histological differentiation. However, no correlations between NUAK1 expression and patients' age, sex, tumor size, location, CA19-9 or CEA were detected. The recurrence-free survival and overall survival were significantly shorter for patients with NUAK1 higher scores than those with NUAK1 lower scores. Multivariate analysis identified NUAK1 was an independent prognostic factor for both recurrence-free survival and overall survival. Our findings provided convincing evidence for NUAK1 overexpression, which was tightly associated with more aggressive tumor behavior and a poor prognosis, indicating that NUAK1 is a valuable molecular biomarker for gastric cancer progression. It might also act as a promising target for both prognostic prediction and therapeutics.

Changes in intracellular redox status influence multidrug resistance in gastric adenocarcinoma cells.

Multidrug resistance (MDR) to chemotherapeutic agents is a major obstacle for the treatment of various types of cancers. The exact mechanism of MDR has not yet been fully clarified, although it has been frequently associated with the variation of intracellular redox status. The levels of intracellular glutathione (GSH) are considered to play a vital role in the regulation of the intracellular redox status. In our study, we investigated the effects of buthionine sulfoximine (BSO), an inhibitor of GSH biosynthesis, and NAC, a cysteine source for GSH synthesis, on sensitive gastric adenocarcinoma cells (SGC7901) and cisplatin-resistant SGC7901/DDP cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The two cell lines were pretreated with various non-toxic concentrations of BSO for 24 h and combined with fluorouracil (5-FU) or mitomycin (MMC) in the presence or absence of NAC before culturing further. After various treatments, the IC(50) values of MMC and 5-FU were calculated and intracellular GSH levels were measured using the glutathione reductase/5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) recycling assay without anticancer drug stimulation under the same microenvironments. The study demonstrated that BSO increased the sensitivity of the cells to chemotherapeutics while NAC exhibited the reverse effect, particularly in drug-resistant cells. It is, therefore, possible that changes in intracellular GSH levels affect the chemosensitivity of the resistant cells to a greater extent than that of their parent cells. This study indicates that variation in the intracellular redox status may be closely correlated with MDR and may provide a valuable basic strategy for anticancer therapy.

[Association of hypoxia-inducible factor 1α expression with microlymphatic vessel density and lymph node micrometastasis in rectal cancer].

OBJECTIVE: To explore the association of the expression of hypoxia-inducible factor 1α (HIF-1α) with microlymphatic vessel density(MLVD) and lymph node micro-metastasis in rectal cancer. METHODS: The experimental group consisted of 40 middle-low rectal cancer specimens pathologically confirmed at the First Affiliated Hospital of Anhui Medical University between 2000 and 2003. Forty samples of normal tissues taken from the corresponding area around the cancer were used as the control group. Immunohistochemistry was used to detect HIF-1α expression and MLVD in both the tumor tissues and the adjacent normal tissues. Lymph node micrometastasis was ascertained using immunohistochemical staining with CK20. RESULTS: In rectal cancer tissues, the HIF-1α expression was 77 386±14 911 and MLVD was 7.3±0.7, significantly higher than those in normal adjacent tissues(33 092±5877 and 0.3±0.2, both P<0.01). The HIF-1α expression was positively correlated with MLVD in rectal cancer(r=0.781, P<0.01). Thirty-one patients had no lymph nodes metastasis and 10 had micrometastasis. The HIF-1α expression and MLVD in specimens with lymph node micrometastasis was significantly higher than that in those without lymph node micrometastasis(P<0.05). CONCLUSION: HIF-1α and MLVD play important roles in the development of rectal cancer,which may promote lymphatic micrometastasis in rectal cancer.

[Anatomical observation of the 'holy plane' for total mesorectal excision].

OBJECTIVE: To provide anatomic evidence for identification of "holy plane" between fascia propria and its adjacent fascia in total mesorectal excision. METHODS: A total of 26 pelvic specimens of adult male preserved in 10% formalin solution were used in this study. Twenty pelvis were employed for topographic anatomy, six for sectional anatomy. RESULTS: Rectovesical septum was formed by the ventral part of the fascia propria and Denonvilliers' fascia, with no blood vessel and nerve coursed between two layers. Dorsal part of the fascia propria parallelled with the presacral fascia, with no blood vessel and nerve coursed between two layers in 80% of the pelvis. However, anatomic variations was encountered occasionally--with muscle-like tissue or fusion of presacral fascia interposed between them for 20%. The lateral space of rectum was between lateral part of the fascia propria and parietal fascia which witnessed pelvic nerve plexus and lateral ligament of the rectum traveling. Pelvic nerve plexus was categorized as two types according the relation between fascia propria and nerve plexus: fusion type accounting for 85% and rarefaction type for 15%. CONCLUSION: 'holy plane' is sandwiched between the fascia propria and its adjacent fascia--ventrally Denonvilliers fascia, dorsally presacral fascia and laterally parietal fascia.

[Correlation of vascular endothelial growth factor D, microlymphatic density and microvessel density with development and metastasis of rectal cancer].

OBJECTIVE: To investigate the correlation of vascular endothelial growth factor D (VEGF-D) expression, microlymphatic density (MLD) and microvessel density (MVD) levels with the development and metastasis of rectal cancer. METHODS: Eighty specimens from resected middle-lower rectal cancer diagnosed by pathology were examined by immunohistochemistry for VEGF-D,MLD and MVD. Simultaneously, 40 biopsy specimens from rectal polyps and 80 specimens from normal rectal tissue were examined as controls. Correlation between the expression of above three factors and the tumor size, gross morphology, histological type, metastasis, differentiation grade, infiltration depth, Dukes stage, lymph node metastasis and long-distance metastasis before operation were investigated with Spearman method. RESULTS: (1) Positive expression rate of VEGF-D was 55 % (44/80) in rectal cancer, and zero in rectal polyps and normal rectal tissues. The expression of VEGF-D in rectal cancer was significantly higher than that in rectal polyps and normal rectal tissues(P<0.05). MLD was significantly higher in rectal cancer (2.80+/-1.31) than that in rectal polyps (0.50+/-0.72) and normal rectal tissues(0.25+/-0.44)(P<0.05).Meanwhile MVD was significantly higher in rectal cancer (80.10+/-23.18) than that in rectal polyps (27.00+/-11.01) and normal rectal tissues (10.45+/-5.34) (P<0.05). (2) VEGF-D, MLD and MVD were positively correlated with lymph node metastasis and long-distance metastasis before operation (P<0.05). (3) VEGF-D was positively correlated with MLD (P<0.05) and MLD was positively correlated with MVD as well(P<0.05). CONCLUSIONS: Lymphangiogenesis exists in rectal cancer tissues. VEGF-D and MLD can be used as good predictors of lymphangiogenesis and they are the important factors affecting biological behavior of rectal cancer. Lymphangiogenesis and angiogenesis may have a cooperative function in the development of rectal cancer.