Quantum confinement in self-assembled two-dimensional nanoporous honeycomb networks at close-packed metal surfaces.

Quantum confinement of a two-dimensional electron gas by supramolecular nanoporous networks is investigated using the boundary elements method based on Green's functions for finite geometries and electron plane wave expansion for periodic systems. The "particle in a box" picture was analyzed for cases with selected symmetries that model previously reported architectures constructed from organic and metal-organic scattering centers confining surface state electrons of Ag(111) and Cu(111). First, by analyzing a series of cases with systematically defined parameters (scattering geometry, potentials, and effective broadening), we demonstrate how the scattering processes affect the properties of the confined electrons. For the features of the local density of states reported by scanning tunneling spectroscopy (STS), we disentangle the contributions of lifetime broadening and splitting of quantum well states due to coupling of neighboring quantum dots. For each system, we analyze the local electron density distribution and relate it to the corresponding band structure as calculated within the plane-wave expansion framework. Then, we address two experimental investigations, where in one case only STS data and in the other case mainly angle-resolved photoemission spectroscopy (ARPES) data were reported. In both cases, the experimental findings can be successfully simulated. Furthermore, the missing information can be complemented because our approach allows to correlate the information obtained by STS with that of ARPES. The combined analysis of several observations suggests that the scattering potentials created by the network originate primarily from the adsorbate-induced changes of the local surface dipole barrier.

[Clinical characteristics and risk factors of newly developed vertebral fractures after vertebral augmentation].

OBJECTIVE: To identify the characteristics and risk factors of the refractures after percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP). METHODS: A retrospective analysis of 148 patients who had undergone PKP or PVP between March 2006 and October 2013 in Peking University People's Hospital was conducted. In the study, 29 patients with 42 refractured vertebra and 119 patients without refracture were included. All the patients were observed for a time of (34.4±26.8) months. Clinical, imaging and procedure related factors (gender, age, height, weight, body mass index, the level of the injured vertebra, the time interval between the procedure and the refracture, the level of the refractured vertebra, the bone cement volume injected, performed PKP or PVP,performed unilateral or bilateral, the percentage of anterior vertebral height restoration, the correction of the Cobb angle, cement diffusion, bone mineral density, presence or absence of diabetes mellitus, history of fractures of the whole body, anti-osteoporosis treatment, cement leakage) for each group were analyzed by Cox proportional hazards regression analysis. RESULTS: Of all the patients,16 (55.17%, 16/29) had refractures in the adjacent vertebra, and 13 (44.83%, 13/29) had refractures in the nonadjacent vertebra. Refractures within 3 months accounted for 31.03% (9/29) of all the refractures, and within 1 year accounted for 55.17% (16/29). Both older age (P=0.027, HR=1.051, 95% CI=1.006-1.098) and a history of fractures of the whole body (P=0.012, HR=0.386, 95% CI=0.184-0.812) were statistically significant as the independent risk factors for predicting refractures. Others were not associated with refractures (P>0.05). CONCLUSION: Older age and a history of fractures of the whole body are the independent risk factors of the refractures after PKP and PVP. The mechanism of the refractures after PKP and PVP is mainly the natural development of osteoporosis.

The identification of sex-specific biomarkers in peripheral blood mononuclear cells from elderly individuals with ischemic stroke.

OBJECTIVE: The aim of this study was to identify sex-specific biomarkers for ischemic stroke (IS) prophylaxis in elderly individuals. MATERIALS AND METHODS: The GSE22255 dataset for elderly individuals with IS was retrieved from the gene expression omnibus database. Thereafter, gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed, as well as gene set enrichment analysis (GSEA). Furthermore, protein-protein interactions (PPIs) were explored using the STRING database, and to screen central genes from the Cytoscape PPI network, corresponding to peripheral blood samples from elderly individuals, we used the molecular complex detection plug-in and cytoHubba. Moreover, a Venn diagram was used to visualize the key genes common among elderly women and men with IS. Statistical analysis was also performed, and receiver operating characteristic (ROC) curves were constructed to evaluate the specificity and sensitivity of the prediction of IS in the elderly. RESULTS: Compared with the healthy controls, in elderly women with IS, 511 biological process (BP) terms, 16 molecular function (MF) terms, and 34 KEGG terms were significantly enriched, whereas in the elderly men with IS, 681 BP terms, 12 MF terms, and 44 KEGG terms were enriched. The GSEA revealed 99 and 140 significantly enriched gene sets in elderly women and men with IS, respectively. Furthermore, in the PPI network, 10 hub genes for each sex with high specificity and sensitivity were identified using ROC curves. CONCLUSIONS: Ten genes for each sex with significant differential expression were also identified in individuals with IS. The novel sex-specific gene targets may be promising diagnostic or prognostic markers and potential therapeutic targets for IS in the elderly.

Gallium Nitride (GaN) High-Electron-Mobility Transistors with Thick Copper Metallization Featuring a Power Density of 8.2 W/mm for Ka-Band Applications.

Copper-metallized gallium nitride (GaN) high-electron-mobility transistors (HEMTs) using a Ti/Pt/Ti diffusion barrier layer are fabricated and characterized for Ka-band applications. With a thick copper metallization layer of 6.8 µm adopted, the device exhibited a high output power density of 8.2 W/mm and a power-added efficiency (PAE) of 26% at 38 GHz. Such superior performance is mainly attributed to the substantial reduction of the source and drain resistance of the device. In addition to improvement in the Radio Frequency (RF) performance, the successful integration of the thick copper metallization in the device technology further reduces the manufacturing cost, making it extremely promising for future fifth-generation mobile communication system applications at millimeter-wave frequencies.

Laparoscopic Witzel gastrostomy--a reappraised technique.

BACKGROUND: Laparoscopic gastrostomy is the best alternative for long-term enteral feeding when percutaneous endoscopic gastrostomy is not possible. The aim of the present study was to determine the feasibility, complications, adequacy of feeding support, and tolerability of laparoscopic Witzel gastrostomy (LWG) in head and neck cancer patients. The initial results and the results of extended follow-up were evaluated. METHODS: A consecutive series of 48 patients with stenotic head and neck or esophageal cancer were referred for laparoscopic gastrostomy. The patients consisted of 42 men and 6 women aged 36 to 82 years (mean, 54 years). After laparoscopic placement of a Foley catheter of 16 F into the stomach, a seromuscular tunnel 4 cm in length is created, embedding the catheter by interrupted sutures. Three stay sutures for gastropexy are fixed and tied on the abdominal skin at the end of the procedure. The mean duration of the procedure was 62.4 +/- 11 min (52-124 min). RESULTS: Laparoscopic Witzel gastrostomy could be performed successfully in all patients with aerodigestive cancer. None of the laparoscopic gastrostomy tube placement procedures was converted to an open surgery, and none of the 48 patients in this series died as a result of the laparoscopic procedure. All LWG complications (11%) were minor, consisting of superficial wound infections, balloon rupture, and chronic granulation. No major complications were encountered. The mean usage time of gastrostomy was 6.3 +/- 5.3 months. CONCLUSIONS: Current techniques of LWG could be an alternative to percutaneous endoscopic gastrostomy (PEG) for long-term enteral access, because it has proved to be safe and reproducible with relatively few complications.

Molecular detection of disseminated tumor cells in the peripheral blood of patients with gastric cancer: evaluation of their prognostic significance.

Early detection of disseminated tumor cells in the peripheral blood of patients with early stage gastric cancer could help to improve the outcome after tumor resection. The aim of this study is to evaluate the prognostic significance of tumor-related mRNA for the detection of circulating tumor cells in gastric cancer patients by a reverse-transcriptase polymerase chain reaction (RT-PCR) method. We simultaneously analyzed human telomerase reverse transcriptase (hTERT), cytokeratin-19 (CK-19), cytokeratin-20 (CK-20) and carcinoembryonic antigen (CEA) mRNA (messenger RNA) expression in the peripheral blood of 42 gastric cancer patients and 30 healthy individuals. Additionally, analyses were carried out for the correlation of these four molecular markers with patients' clinicopathologic features, as well as the occurrence of postoperative recurrence/metastasis. Among 42 gastric cancer patients, the prevalence of mRNA for hTERT, CK-19, CK-20, and CEA was 61.9% (26/42), 69% (29/42), 61.9% (26/42), and 78.6% (33/42), respectively. All 30 healthy individuals were negative for hTERT and CEA mRNA, while two were positive for either CK-19 mRNA or CK-20 mRNA. Positive CEA mRNA was significantly correlated with tumor size p=0.008), vessel invasion (p=0.001), depth of tumor invasion (p=0.007), lymph node metastasis (p< 0.001), and TNM stage (p<0.001). In addition, the multivariate logistic regression demonstrated that CEA mRNA expression was an independent and significant predictor for postoperative recurrence/metastasis (p=0.032). Our findings suggest that CEA mRNA may be a more reliable marker than hTERT, CK-19 and CK-20 for the detection of circulating cancer cells in gastric cancer patients' peripheral blood. Patients with positive CEA mRNA expression in peripheral blood have a significantly higher risk of postoperative recurrence/metastasis.

EB-virus latent membrane protein 1 potentiates the stemness of nasopharyngeal carcinoma via preferential activation of PI3K/AKT pathway by a positive feedback loop.

Our previous study reported that Epstein-Barr virus(EBV)-encoded latent membrane protein 1 (LMP1) could induce development of CD44(+/High) stem-like cells in nasopharyngeal carcinoma (NPC). However, the molecular mechanisms that underlie modulation of cancer stem cells (CSCs) in NPC remain unclear. Here, we show that LMP1 induced CSC-like properties through promotion of the expression of epithelial-mesenchymal transition-like cellular markers and through alterations in differentiation markers. Furthermore, LMP1 activated and triggered phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway, which subsequently stimulated expression of CSC markers, development of side population and tumor sphere formation. This suggests that PI3K/AKT pathway has an important role in the induction and maintenance of CSC properties in NPC. Similarly, PI3K/AKT pathway was also activated by phosphorylase in LMP1-induced CD44(+/High) cells. In addition, LMP1 greatly increased expression of miR-21 and downregulated expression of the miR-21 target, PTEN. Overexpression of miR-21 by transfection of miR-21 mimics into LMP1-transformed cells led to phosphorylase-mediated activation of the PI3K/AKT pathway and induction of CSCs. On the contrary, phosphorylation of the PI3K/AKT pathway and the expression of CSC were reversed by an miR-21 inhibitor. The specific inhibitor (Ly294002) of PI3K/AKT pathway significantly decreased expression of miR-21 and CSC markers and upregulated the expression of PTEN, which indicates that miR-21 and PTEN are the downstream effectors of PI3K/AKT and that expression of these two effectors are related to the development of NPC CSCs. Taken together, our novel findings indicate that LMP1, PI3K/AKT, miR-21 and PTEN constitute a positive feedback loop and have a key role in LMP1-induced CSCs in NPC.

Overproduction of mycobacterial ribosomal protein S13 induces catalase/peroxidase activity and hypersensitivity to isoniazid in Mycobacterium smegmatis.

A Bacillus Calmette Guerlin (BCG) DNA fragment was identified which conferred hypersensitivity to isoniazid (INH) upon Mycobacterium smegmatis (Ms) when present on a multicopy plasmid. The gene cluster present on this fragment contains the genes encoding ribosomal proteins L36 (rpmJ), S13 (rpsM), S11 (rpsK) and S4 (rpsD), as well as the gene encoding initiation factor-1 (infA), an open reading frame of unknown function (ORFX) and a putative promoter region. The rpsM gene, from either BCG or Ms is necessary and sufficient to produce the INH-hypersensitive phenotype in Ms, but the gene cluster has no effect on INH sensitivity when introduced into BCG on a multicopy plasmid. The presence of rpsM on a multicopy plasmid also causes an increase in catalase/peroxidase (Kat/Prx) activity in Ms. The overproduction of S13 may induce a stress response, resulting in increased expression of katG (encoding Kat/Prx) in Ms, thereby causing hypersensitivity to INH.

Heme oxygenase-2 interaction with metalloporphyrins: function of heme regulatory motifs.

Heme oxygenase-2 (HO-2) degrades heme [Fe-protoporphyrin IX (Fe-PP)] to CO and bilirubin. The enzyme is a hemoprotein and interacts with nitric oxide. HO-2 has two copies of heme regulatory motif (HRM) with a conserved core of Cys264-Pro265 and Cys281-Pro282. We examined interaction of HO-2 HRMs with Fe-PP, Zn-protoporphyrin IX (Zn-PP; HO-2 inhibitor), and protoporphyrin IX (PP IX). Spectral analyses, using 1:4 or 1:1 molar ratio of the heme to 10-residue peptides, corresponding to HRM containing HO-2 sequences, revealed specific interactions as indicated by a shift in the absorption spectrum of heme. Five residue peptides qualitatively produced similar results. Substitution of cysteine with alanine in either peptide eliminated interactions, and substitution of proline with alanine reduced the peptides' affinity for heme. Neither Zn-PP nor PP IX absorption spectrum was affected by HRM peptides. The circular dichroism spectra confirmed heme-HRM peptides interactions. An astounding 4,000-6,000-fold higher concentrations of KCN were required at pH 7.5 to displace HRM peptides from heme. Data suggest (a) each HRM can contribute to HO-2-heme interaction, (b) heme iron interacts with cysteine thiol, (c) charged residues upstream of Cys264-Pro265 result in its high-affinity heme binding, and (d) inhibition of HO-2 activity by synthetic metalloporphyrins does not involve HRMs. We suggest that heme bound to HRMs may serve as a binding site/reservoir for gaseous signal molecules.

A novel transcription factor inhibitor, SP100030, inhibits cytokine gene expression, but not airway eosinophilia or hyperresponsiveness in sensitized and allergen-exposed rat.

1. We examined the effect of SP100030, a novel inhibitor of activator protein-1 (AP-1) and nuclear factor (NF)-kappa B transcription factors, in a rat model of asthma. 2. Sensitized Brown-Norway rats were treated with SP100030 (20 mg kg(-1) day(-1) for 3 days) intraperitoneally prior to allergen challenge. Allergen exposure of sensitized rats induced bronchial hyperresponsiveness (BHR), accumulation of inflammatory cells in bronchoalveolar lavage (BAL) fluid, and also an increase in eosinophils and CD2(+), CD4(+) and CD8(+) T-cells in the airways together with mRNA expression for IL-2, IL-4, IL-5, IL-10, and IFN-gamma. 3. Pre-treatment with SP100030 inhibited BAL lymphocyte influx (P<0.03), specifically reduced CD8(+) T-cell infiltration in the airway submucosa (P<0.03), and mRNA expression for IL-2, IL-5, and IL-10 (P<0.05). Neutrophil, eosinophil, and CD4(+) T-cells accumulation in the airways and BHR were not affected by SP100030. 4. Our results indicate that suppression of IL-2 and IL-5 mRNA expression may not necessarily lead to suppression of BHR. The expression of IL-5 mRNA may contribute to the airway accumulation of eosinophils, but does not correlate with the extent of eosinophilia. 5. The joint AP-1 and NF-kappa B inhibitor, SP100030, selectively inhibits CD8(+) T-cells, and mRNA expression of both Th1 and Th2 cytokines in vivo, but does not inhibit allergen-induced airway eosinophilia and BHR.

Involvement of cysteinyl leukotrienes in airway smooth muscle cell DNA synthesis after repeated allergen exposure in sensitized Brown Norway rats.

Airway smooth muscle thickening is a characteristic feature of airway wall remodelling in chronic asthma. We have investigated the role of the leukotrienes in airway smooth muscle (ASM) and epithelial cell DNA synthesis and ASM thickening following repeated allergen exposure in Brown Norway rats sensitized to ovalbumin. There was a 3 fold increase in ASM cell DNA synthesis, as measured by percentage bromodeoxyuridine (BrdU) incorporation, in repeatedly ovalbumin-exposed (4.1%, 3.6-4.6; mean, 95% c.i.) compared to chronically saline-exposed rats (1.3%, 0.6-2.1; P<0.001). Treatment with a 5-lipoxygenase enzyme inhibitor (SB 210661, 10 mg kg(-1), p.o.) and a specific cysteinyl leukotriene (CysLT1) receptor antagonist, pranlukast (SB 205312, 30 mg kg(-1), p.o.), both attenuated ASM cell DNA synthesis. Treatment with a specific leukotriene B4 (BLT) receptor antagonist (SB 201146, 15 mg kg(-1), p.o.) had no effect. There was also a significant, 2 fold increase in the number of epithelial cells incorporating BrdU per unit length of basement membrane after repeated allergen exposure. This response was not inhibited by treatment with SB 210661, pranlukast or SB 201146. A significant increase in ASM thickness was identified following repeated allergen exposure and this response was attenuated significantly by SB 210661, pranlukast and SB 201146. Rats exposed to chronic allergen exhibited bronchial hyperresponsiveness to acetylcholine and had significant eosinophil recruitment into the lungs. Treatment with SB 210661, pranlukast or SB 201146 significantly attenuated eosinophil recruitment into the lungs, whilst having no significant effect on airway hyperresponsiveness. These data indicate that the cysteinyl leukotrienes are important mediators in allergen-induced ASM cell DNA synthesis in rats, while both LTB4 and cysteinyl leukotrienes contribute to ASM thickening and eosinophil recruitment following repeated allergen exposure.

Autotransplantation of parathyroid glands into subcutaneous forearm tissue for renal hyperparathyroidism.

BACKGROUND: Autotransplantation of diseased parathyroid glands into subcutaneous adipose tissue has been mentioned previously, but as far as we know there is no previous systemic study concerning parathyroid function after subcutaneous autotransplantation. METHODS: From January 1993 to June 1996, total parathyroidectomy and autotransplantation were carried out in 46 patients with renal hyperparathyroidism. The symptoms and signs before operation were intractable pruritus in 29 patients (63%), bone pain in 27 patients (58.7%), general weakness in 17 patients (37%), soft tissue calcification in 15 patients (32.6%), bone fracture in one patient, and failure to thrive in one patient. Twenty-four patients (group A) underwent autotransplantation of 60 mg of a diffuse hyperplastic parathyroid gland into subcutaneous forearm tissue, and 22 patients (group B) underwent autotransplantation of 15 pieces (60 mg) of 1 mm3 tissue into forearm muscles, as mentioned previously. Four patients in group A and one in group B who had high levels of intact parathyroid hormone (I-PTH) immediately after operation were excluded. After the operation, calcium carbonate, 1.5 to 16 gm daily, and calcitriol, 0.25 to 1.5 micrograms/daily, were prescribed according to the patients' calcium levels. RESULTS: After 6 months, all patients in both groups were given calcium carbonate, 1 gm/day, and calcitriol, 0.25 microgram/day, for parathyroid suppression, and none had to take more medicine to maintain calcium levels. There were no significant differences between the two groups regarding serum calcium, phosphorous, alkaline phosphatase, and I-PTH levels 1 week, 3 to 6 months, and 1 year after operation. Eighteen patients in group A and 19 patients in group B had normal levels of I-PTH 1 year after operation. In the follow-up period from 1 to 3 1/2 years, only one patient in group A had a subnormal I-PTH level and one in group B had graft-dependent hyperparathyroidism. CONCLUSIONS: We therefore suggest that autotransplantation of a parathyroid gland into forearm subcutaneous tissue for renal hyperparathyroidism is as effective as autotransplantation into forearm muscles and can be done easier.

Inhibition of ozone-induced lung neutrophilia and nuclear factor-kappaB binding activity by vitamin A in rat.

Vitamin A binds to retinoic acid receptors, which in turn may interact with other transcription factors. We determined its effect (2500 and 5000 IU/kg) on nuclear factor-kappaB binding activity in the lung, airway inflammation and bronchial hyperresponsiveness in rats exposed to ozone. Ozone (3 ppm, 3 h) caused neutrophil influx into bronchoalveolar lavage fluid (16.2+/-0.8 x 10(5) cells/ml, p < 0.01) and bronchial hyperresponsiveness (-logPC200ACh = 2.54+/-0.19, p < 0.05, compared to control animals, respectively). Vitamin A inhibited this neutrophilia dose-dependently together with the increased DNA-binding activity of nuclear factor-KB in lung extracts. Vitamin A did not affect bronchial hyperresponsiveness at both doses. Vitamin A inhibits ozone-induced neutrophilic inflammation through a reduction in nuclear factor-kappaB DNA binding activity.

Mutations of p53 gene in gastric carcinoma in Taiwan.

BACKGROUND: p53 gene mutation and p53 protein accumulation is the most common event in human cancers. The present study was conducted to investigate the occurrence of p53 mutations in patients with gastric carcinoma in Taiwan. MATERIALS AND METHODS: Tumor samples from 36 patients with primary gastric carcinoma undergoing radical gastrectomy were evaluated. The mutational status of the p53 (exons 5 to 8) was screened by polymerase chain reaction/single strand conformation polymorphism (PCR-SSCP) analysis followed by direct sequencing. These results were compared with p53 protein expression as assessed by immunohistochemical staining. RESULTS: Of all 36 gastric carcinomas, mutations of the p53 gene were found in 7 cases (19.4%). These results from direct sequencing indicated that mutations consisted of five missence mutations, one silent mutation and one mutation within the splice donor site of intron 5. Mutations were found at codon 145 in exon 5 (1 case), intron 5 (1 case), codon 248 in exon 7 (1 case), codon 251 in exon 7 (2 cases), codon 285 in exon 8 (1 case) and codon 287 in exon 8 (1 case). The mutation hot spot at codon 251 in gastric cancer has not been observed previously. Over-expression of p53 oncoprotein was observed in 10 patients (27.8%) immunohistochemically. CONCLUSIONS: p53 gene mutation might contribute to the pathogenesis of human gastric carcinoma. However, the suggestion awaits further investigation for confirmation.

Effect of nasal continuous positive airway pressure on methacholine-induced bronchoconstriction.

Bronchial hyper-responsiveness is a cardinal feature of asthma. To determine whether nasal continuous positive airway pressure (NCPAP) influences airway smooth muscle in response to exogenous stimuli, we examined the effect of NCPAP on aerosolized methacholine-induced bronchoconstriction in 16 stable asthmatic patients. The dose-response curve for each subject was measured by a log transformation and linear regression analysis as well as a formula fitted to the data points to obtain values for a (slope) and b (position). The PD20FEV1 significantly increased in patients receiving 8 cmH2O of NCPAP by one doubling dose compared with that in patients using sham pressure. NCPAP shifted the dose-response curves to be flatter, deviated upwards and to the right. The coefficient a, indicating bronchial reactivity, was significantly lower in patients receiving NCPAP. The coefficient b, indicating the bronchial sensitive threshold, was higher after applying NCPAP. In contrast, coefficients a and b did not change in subjects with sham pressure. NCPAP also significantly enhanced the bronchodilator effect of inhaled salbutamol in response to methacholine-induced bronchoconstriction. In summary, we have shown that NCPAP therapy improves bronchial smooth reactivity with an increase in PD20FEV1 and a reduction in the bronchial reactivity and bronchial sensitivity. Therefore, NCPAP may provide an adjuvant therapy in patients with acute bronchial asthma.

Video-assisted endoscopic lumbar discectomy.

BACKGROUND: The optimal management of symptomatic lumbar disc herniations (LDH) remains controversial. This study examines the feasibility and safety of a video-assisted endoscopic intracanalicular technique for managing symptomatic LDH. METHODS: From September 1999 to June 2000, we used the current technique, the Vertebroscope System, on 11 patients (six men, five women), aged from 18 to 61 years (mean, 45), who had suffered symptomatic LDH. The disc levels involved were at L4-L5 (n = 8), and L5-S1 (n = 3). The Vertebroscope, which has a 30 degrees viewing angle and a working channel 1.7 cm in diameter, was used for the minimally invasive endoscopic procedures. The mean follow-up period was 12 months (range, 6-15). RESULTS: The operating time ranged from 60 to 335 min (mean, 136.5), and the estimated blood loss during operation was minimal to 200 ml. The mean length of the paramedian skin incisions was 2 cm. No drainage tube was used postoperatively. The mean hospital stay was 3 days (range, 2-5), with five patients discharged on the 1st postoperative day. Complications included one superficial wound infection, one conversion to an open procedure when muscle herniation into the working channel created a technical difficulty in approaching the ligamatum flavum, and one minor tear of the nerve root sleeve that did not require further surgery. In the first five patients studied herein, the mean operating time was significantly longer than that for the later five patients (201 vs 72 min, p < 0.001). CONCLUSIONS: The advantages of the current endoscopic disectomy technique include its minimally invasive character, with less paraspinal muscle trauma, direct address to the lesion site that resembles the open technique, and enhanced operative field visualization with a paramedian skin incision of just 2 cm. Practice is needed to perfect such an endoscopic approach for lumbar disc excision, so the operating time decreased significantly as the surgeons became more familiar with this endoscopic technique. It has proved to be safe and effective for treating patients with symptomatic LDH.

Modified devascularization surgery for isolated gastric varices assessed by endoscopic ultrasonography.

BACKGROUND: This study aimed to assess the role of endoscopic ultrasonography (EUS) in the surgical management of isolated gastric varices (IGV), and to report the authors' experience in the treatment of IGV with modified devascularization surgery. METHODS: In this study, 26 cirrhotic patients with IGV were treated with devascularization surgery for variceal hemorrhage. Preoperatively, percutaneous transhepatic portography (PTP) and EUS were used to determine the mode of therapy for IGV. Fundectomy was performed for 14 patients with fundic IGV, whereas 12 patients with cardiac IGV underwent proximal gastrectomy. RESULTS: A significantly higher proportion of patients with cardiac varices showed grade 3 IGV on preoperative EUS than those who had fundic varices (p < 0.05). No major complications were observed during or after the operation, and only one patient died of prolonged shock and massive transfusion. Postoperatively, gastric varices had been eradicated completely in 25 of 26 patients, as determined by EUS study. During a mean follow-up period of 50 months, two patients had recurrent varices without bleeding, as demonstrated by EUS. The overall 5-year survival rate for the fundic IGV group was 67.9%, whereas that for the cardiac IGV group was 64.3% (p > 0.05). CONCLUSIONS: This study showed that devascularization surgery is highly effective for the prevention of recurrent bleeding from IGV and provides an alternative treatment method. Preoperatively, EUS is very helpful in detailed devascularization of patients with specific IGV, and may be used also for postoperative follow-up evaluation.

Effects of moisture content and endodontic treatment on some mechanical properties of human dentin.

The objective of this study was to determine whether significant differences exist between the mechanical properties of human dentin from treated pulpless teeth and dentin from normal vital teeth. Dentin specimens (n = 262) were obtained from 54 freshly extracted normal vital human teeth and 24 treated human pulpless teeth. These specimens were subjected to different experimental conditions (wet, air dried, desiccated, and rehydrated). Compression, indirect tensile, and impact tests were conducted to measure the mechanical properties of those specimens. All data obtained were analyzed with t tests. The results showed that the dehydration of dentin increases the Young's modulus, proportional limit (in compression), and especially the ultimate strength (in both compression and tension). Substantial dehydration changes the fracture characteristics of dentin specimens under static compressive and indirect tensile loadings. The measurements of impact-breaking energies of desiccated dentin were not found to be significantly decreased. The compressive and tensile strengths of dentin from treated pulpless teeth obtained in this study do not appear to be significantly different from those of normal dentin (p > 0.05), while the mean values of Young's modulus and proportional limit in compression tests appear to be lower. Fifty percent of the dentin specimens from treated pulpless teeth exhibit greater plastic deformation than normal dentin in compression. The results of this study do not support the theory that dehydration after endodontic treatment per se weakens dentin structure in terms of compressive and tensile strengths. Other mechanical properties of treated pulpless teeth, however, may not be the same as those of normal vital teeth.

Secure placement of continuous ambulatory peritoneal dialysis catheters under laparoscopic assistance.

Laparoscopic surgical procedures were performed in 18 patients with end-stage renal disease for the placement of a Tenckhoff peritoneal dialysis catheter. Among them, 6 patients had received previous lower abdominal surgical treatment and 3 patients underwent laparoscopic rescue of dysfunctional Tenckhoff catheters. The operating time was between 40 and 80 minutes (median, 50 minutes). After a median follow-up period of 11 months, the short-term results revealed that no significant morbidity was associated with this procedure, and all catheters except two functioned well postoperatively. One of the catheters was not functional because of the patient's death, and the other one was removed because of persistent peritonitis. Laparoscopic secure placement of continuous ambulatory peritoneal dialysis catheters appears to be a simple, safe, and viable procedure, even in patients with previous lower-abdominal operations. The same technique can be used to rescue dysfunctional catheters that are displaced or obstructed by adhesion and omental wrapping, thus increasing catheter longevity.

The role of epidermal growth factor in gastric epithelial proliferation in portal hypertensive rats exposed to stress.

BACKGROUND/AIMS: This study was designed to determine whether epidermal growth factor may have a role in the stomach of portal hypertensive rats after exposure to water immersion and restraint stress. METHODOLOGY: Rats with portal hypertension (portal vein partial ligation) were studied to determine the proliferative response of the gastric epithelium to epidermal growth factor (EGF) during stress. The portal hypertensive rats received EGF (0, 10, 25, 50, and 100 microg/kg/day) subcutaneously for 7 days before water immersion restraint stress. Each rat was subjected to water immersion restraint stress for 6 hours, at the end of which the stomachs were excised to evaluate gross and microscopic mucosal damage, and gastric epithelial proliferation using proliferating cell nuclear antigen (PCNA) immunoreactivity. RESULTS: The gross and microscopic mucosal damage were significantly greater in control or low dose EGF-pretreated (10 or 25 microg/kg/day) rats than in high dose EGF-pretreated (50 or 100 microg/kg/day) rats (p<0.01). These changes were accompanied by parallel alterations in the PCNA labeling index. The PCNA labeling index between high dose EGF-pretreated and control or low dose EGF-pretreated rats differed significantly (p<0.01). CONCLUSIONS: This study clearly indicates that the influence of EGF on the proliferative response of the portal hypertensive (PHT) gastric epithelium to stress in rats was dose-dependent, suggesting an important role for EGF in the protection of PHT gastric mucosa from stress injury.