[Tanshinone ⅡA activates PI3K/AKT signaling pathway to inhibit the apoptosis of mice cochlear pericytes induced by high glucose]

Objective: To investigate whether tanshinone ⅡA can protect the apoptosis of mice cochlear pericytes induced by high glucose and its specific protective mechanism, so as to provide experimental evidence for the prevention and treatment of diabetic hearing loss. Methods: C57BL/6J male mice were used to prepare type 2 diabetes model, which were divided into normal (NG) group, diabetic (DM) group, diabetic+tanshinone ⅡA (HG+tanshinone ⅡA) group and tanshinone ⅡA group. Each group had 10 animals. Primary cochlear pericytes were divided into NG group, HG group (high glucose 35 mmol/L), HG+tanshinone ⅡA (1, 3, 5 μmol/L) group, HG+Tanshinone ⅡA+LY294002 (PI3K/AKT pathway inhibitor) group, LY294002 group, tanshinone ⅡA group and DMSO group. Auditory brainstem response (ABR) was used to measure hearing threshold. Evans blue was used to detect the permeability of blood labyrinth barrier in each group. TBA methods were used to detect oxidative stress levels in various organs of mice. Morphological changes of stria vascularis were observed by hematoxylin-eosin staining (HE). Evans blue was used to detect the vascular labyrinth barrier permeability in cochlea. The expression of apoptosis protein in stria vascularis pericytes was observed by immunofluorescence. Pericytes apoptosis rate was observed by flow cytometry. DCFH-DA was combined with flow cytometry to detect intracellular ROS content, and Western blot was used to detect the expression of apoptotic proteins (Cleaved-caspase3, Bax), anti-apoptotic proteins (BCL-2) and pathway proteins (PI3K, p-PI3K, AKT, p-AKT). SPSS software was used for statistical analysis. Independent sample t test was performed, and P<0.05 was considered statistically significant. Results: Animal experiments: Tanshinone ⅡA decreased the hearing threshold of DM group [(35.0±3.5) dB SPL vs. (55.3±8.1) dB SPL] (t=4.899, P<0.01), decreased the oxidative stress level in cochlea (t=4.384, P<0.05), improved the structure disorder, atrophy of cochlea vascular lines, vacuole increased phenomenon. Tanshinone ⅡA alleviated the increased permeability of the blood labyrinth barrier [Evans blue leakage (6.84±0.27) AU vs. (8.59±0.85) AU] in the cochlea of DM mice (t=2.770, P<0.05), reversed the apoptotic protein: Caspase3 (t=4.956, P<0.01) and Bax (t=4.388, P<0.05) in cochlear vascularis. Cell experiments: Tanshinone ⅡA decreased intracellular ROS content in a concentration-dependent way (t=3.569, P<0.05; t=4.772, P<0.01; t=7.494, P<0.01); Tanshinone ⅡA decreased apoptosis rate and apoptotic protein, and increased the expression of anti-apoptotic protein, p-PI3K/PI3K and p-AKT/AKT in concentration-dependent manner (all P values<0.05); LY294002 reversed the protective effect of tanshinone ⅡA on pericytes apoptosis (all P values<0.05). Conclusion: Tanshinone ⅡA can inhibit the apoptosis of cochlear pericytes induced by high glucose by reducing oxidative stress level and activating PI3K/AKT signaling pathway under high glucose environment, thus playing a protective role in diabetic hearing loss.

[Efficacy of sacubitril/valsartan in peritoneal dialysis patients with HFpEF and its effect on residual renal function]

Objective: To investigate the efficacy of sacubitril/valsartan in peritoneal dialysis (PD) patients with heart failure with preserved ejection fraction (HFpEF) and its effect on residual renal function. Methods: PD patients with HFpEF in Ningbo First Hospital from March 2018 to August 2021 were retrospectively enrolled and divided into study group with sacubitril/valsartan and control group with valsartan. The clinical baseline data before treatment and clinical indicators during follow-up (6 and 12 months after treatment) were collected and compared between the two groups, and the adverse reactions were also recorded. Results: A total of 99 patients were included in the study. There were 61 patients in the study group, including 44 males and 17 females, with a mean age of (52±13) years. Meanwhile, there were 38 patients in the control group, including 23 males and 15 females, with a mean age of (57±14) years. There was no statistically significant difference in clinical baseline data between the two groups (e.g., age, sex, body mass index, duration of dialysis) (all P>0.05). The N-terminal pro-B-type natriuretic peptide (NT-proBNP) and left ventricular end-systolic dimension (LVDs) were lower, but the left ventricular ejection fraction (LVEF) was higher in the study group than those in the control group at 6 and 12 months after treatment (all P<0.05). The systolic blood pressure (SBP) and diastolic blood pressure (DBP) of the two groups were lower than baseline values at 6 and 12 months after treatment respectively, with statistically significant differences (all P<0.05). However, there were no statistically significant differences in the decreases of SBP and DBP between the two groups at 6 and 12 months after treatment (all P>0.05). The decrease extents in residual estimated glomerular filtration rate (eGFR) [0.52 (-0.05, 1.19) vs 1.72 (0.97, 2.39) ml·min^-1·(1.73 m²)^-1, P<0.001]and 24-h residual urine volume [200 (-100, 300) vs 300 (137, 400) ml, P=0.018] at 12 months after treatment were lower in the study group than those in the control group. During the follow-up period, hyperkalemia occurred in 16 cases (26.2%) and 13 cases (34.2%) in the study group and the control group, and hypotension occurred in 3 cases (4.9%) and 1 case (2.6%) in the study group and the control group, respectively. There were no adverse reactions such as cough and angioneurotic edema in the two groups. Conclusions: Sacubitril/valsartan can safely and effectively improve cardiac function and lower blood pressure in PD patients with HFpEF. Compared with valsartan, sacubitril/valsartan may be more beneficial to delay the loss of residual renal function in PD patients with HFpEF.

[The urate-lowering efficacy of febuxostat and its relationship with residual renal function in peritoneal dialysis patients with hyperuricemia]

Objective: To investigate the urate-lowering efficacy of febuxostat in peritoneal dialysis (PD) patients with hyperuricemia (HUA) and its relationship with residual renal function. Methods: Patients with HUA who underwent PD in Ningbo First Hospital from January 2018 to October 2021 were enrolled and divided into experimental group and control group according to whether to use febuxostat. The clinical baseline data before treatment and clinical indicators during 1-12 months after treatment were collected in two groups, and the adverse reactions during the use of febuxostat were also recorded. The changes of serum uric acid, standard-reaching rate and residual renal function were compared between the two groups during the follow-up. Results: A total of 105 patients were included in the study. There were 55 patients in the experimental group [27 males and 28 females, with a mean age of (54.5±14.8) years] and 50 patients in the control group [32 males and 18 females, with a mean age of (53.8±15.2) years]. No statistically significant difference was detected in clinical baseline data between the two groups (all P>0.05). The serum uric acid of the experimental group [(479±77), (311±69), (286±61), (307±65), (312±57) μmol/L] and control group [(486±59), (454±71), (453±76), (463±70), (459±76) μmol/L] were lower than baseline values at 1, 3, 6 and 12 months after treatment and the differences of two groups were statistically significant (all P<0.05). The serum uric acid in experimental group was significantly lower than that of control group (P<0.05). At 1, 3, 6 and 12 months after treatment, the standard-reaching rate of serum uric acid in the experimental group was significantly higher than that of the control group (all P<0.05). The decrease of residual estimated glomerular filtration rate (eGFR) and residual renal urea clearance index (Kt/V) in the experimental group were significantly lower than those in the control group at 12 months after treatment (all P<0.05). During the follow-up, the incidence of adverse reactions in the experimental group was 9.09% (5/55). Conclusions: Febuxostat can effectively treat PD patients with hyperuricemia and has a high safety profile. Moreover, it may delay the loss of residual renal function.

[Effect of microvascular pericytes of cochlear stria vascularis on endothelial cell permeability in C57BL/6J mice]

Objective: To study the changes in the permeability of the blood labyrinth barrier of the aging cochlea in mice, and to establish a non-contact co-culture model of endothelial cells (EC) and pericytes (PC) to furtherly investigate the cochlear stria vascularis microvascular pericytes impact on the permeability of endothelial cells. Methods: C57BL/6J mice were divided into two groups, three months old as young group, 12 months old as senile group. Cell experiment was divided into four groups, EC group, EC+PC co-culture group, D-gal+EC group and D-gal+EC+PC co-culture group. Auditory brainstem response (auditory brain response, ABR) was used to detect the auditory function of the two groups of mice. Evans blue staining was applied to detect the permeability of the cochlear blood labyrinth barrier of the two groups of mice. Transmission electron microscopy was used to observe the ultrastructure of blood labyrinth barrier endothelial cells, pericytes and tight junctions in the two groups of mice. Immunohistochemistry was used to detect the expression levels of tight junction proteins in the stria vascularis of the cochlea of the two groups of mice. Transwell chamber was used to detect the permeability of endothelial cells. Western blot and immunofluorescence technology were used to detect the expression level of tight junction protein on endothelial cells. SPSS 20.0 software was used to analyze the data. Results: Compared with the young group, the ABR threshold of the aging group was significantly increased, the latency of wave I was prolonged (t=10.25, P<0.01;t=5.61, P<0.05), the permeability of the cochlear blood labyrinth barrier was increased and the expression of tight junction protein on the vascular stria was decreased (P<0.05). The cochlear ultrastructure showed that the cochlear vascular stria microvascular lumen was deformed, the basement membrane thickened and the tight junction gap between endothelium enlarged. The positive rate of ECs and PCs in primary culture was more than 95%. The cells induced by 15 g/L D-gal were determined to be senescent cells. Compared with EC group, the expression of tight junction protein in endothelial cells of D-gal+EC group decreased（t=7.42，P<0.01；t=13.19，P<0.05）and the permeability increased (t=11.17, P<0.01). In the co-culture group, the expression of tight junction protein between endothelial cells in EC+PC co-culture group and D-gal+EC+PC co-culture group increased and the permeability decreased. Conclusions: In aging mice, the permeability of cochlear blood labyrinth barrier will increase and the level of tight junction protein will decrease; in aging state, cochlear vascular stria microvascular pericytes may affect endothelial cell permeability by regulating the expression of tight junction protein.

[Merkel cell carcinoma: a clinicopathological study of 10 cases]

Objective: To investigate the clinicopathological features, differential diagnosis and prognosis of Merkel cell carcinoma (MCC). Methods: The clinical and pathological data of 10 patients with MCC were collected at the 940th Hospital of PLA. The histological characteristics were examined. Immunohistochemical EnVision method was used to detect thyroid transcription factor-1 (TTF1), broad-spectrum cytokeratin (CKpan), CK20, S-100, Ki-67, CD56, chromogranin A, synaptophysin and other markers in the 10 cases. Results: Intradermal MCC of the skin showed a nested, cord-like, cribriform distribution, polygonal cells, uniform size, and lack of cytoplasm. Tumor cell nuclei were large and round, with clear nuclear membranes, fine and scattered chromatin, absence of nucleoli, and mitotic figures of 10 per 50 high power fields. Among them, one patient had sarcoma and squamous cell carcinoma in situ, one patient had squamous cell carcinoma in situ, and one patient had unique cell morphology. Immunohistochemical staining showed that all cancer cells expressed CKpan, synaptophysin and CD56. There were seven cases with perinuclear dot-like positivity of CK20. Six MCCs expressed chromogranin A to varying degrees, while 2 MCCs were weakly positive for p63. The nuclear positive index in the Ki-67 hotspot area was 60%. Conclusion: The histology of MCC varies. Rendering a correct diagnosis of MCC requires adequate sampling, close correlation with clinical history and rational use of immunohistochemical staining. The treatment requires standardized surgery, postoperative radiotherapy and multimodal chemotherapy. Immunotherapy may replace the traditional treatment in the future.

[Detection and analysis of FAM19A4 promoter methylation in cervical exfoliated cells]

Objective: To investigate the cinical value of FAM19A4promoter methylation in cervicalexfoliated cells for triage of cervical cancer. Methods: A total of 162 high-risk HPV-infected patients who were pathologically confirmed as different cervical lesions from August 2017 to December 2017 were collected in Guangdong Women and Children Hospital. Taqman probe-based quantitative PCR (qPCR) was used to detect the methylation of FAM19A4 promoterin different grades of cervical lesions, and the value of FAM19A4 methylation in predicting cervical HSIL and the above lesions was calculated by diagnostic test. Results: (1)The positive rates of FAM19A4 methylation in cervical exfoliated cells increased with the severity of cervical lesions, which were 7.69% (4/52) , 34.62% (9/26) , 55.56% (20/36) , 95.83% (46/48) in normal cervix/cervicitis, cervical LSIL, HSIL, and cervical cancer, respectively(P<0.05).(2)There was no significant difference in the detection rates of FAM19A4 methylation between different age groups, pathological types, clinical stage, tumor size and lymph node metastasis status (P>0.05). (3) The specificity and positive predictive value of FAM19A4 methylation in detecting cervical HSIL alone and ≥HSIL lesions were the optimal, with the AUC of 0.69 and 0.84, respectively. When combined with HPV16/18 genotyping, the sensitivity was significantly improved. Conclusions: The detection of FAM19A4 promoter methylation in cervical exfoliated cells has a high clinical value of discriminating ≥HSIL lesions; and the cotest of methylated FAM19A4 and HPV16/18 genotyping can identify ≥HSIL lesions more sensitively.

[Experimental studies on correlation between nucleolus spindle-related protein 1 and the malignant progression and prognosis of human glioblastoma multiforme]

Objective: To investigate the correlation between nucleolus spindle-related protein 1 (NUSAP1) and malignant progression and prognosis of human glioblastoma multiforme (GBM). Methods: RT-PCR and immunohistochemical technique were applied to analyze NUSAP1 expression level in GBM surgical specimens. Correlations between NUSAP1 expression and molecular classification and survival of patients with GBM were also investigated in TCGA database. The gene silencing technique was used to silence NUSAP1 expression in U87 cells, CCK-8 assay was used to detect cell proliferation, flow cytometry was used to detect cell cycle changes, and in vivo tumorigenicity was evaluated after NUSAP1 silencing in tumor-bearing mice. Results: NUSAP1 expression level in GBM was higher than that in non-tumor brain tissue. Survival curve analysis showed that the survival time of GBM patients with high NUSAP1 expression decreased significantly (P<0.01). NUSAP1 expression was relatively lower in mesenchymal and neural molecular subtypes of GBM, when compared with the other two molecular subtypes. And it was closely related with specific genetic aberrations (such as PTEN loss and IDH1 mutation). Silencing NUSAP1 inhibited G2/M cell cycle progression of GBM cells, and inhibited cell proliferation both in vitro and in vivo. Conclusion: Expression of NUSAP1 is closely related to progress and prognosis of GBM, and can be a biomarker reflecting GBM prognosis and act as a therapeutic target with potential clinical application value.

[Experimental study of glioma stem cell-mediated immune tolerance in tumor microenvironment]

Objective: To investigate the tumor microenvironment of immune tolerance induced by glioma stem cells (GSC). Methods: Human GSC SU3 cells transfected with red fluorescent protein (SU3-RFP) gene were implanted into the brain, subcutis (armpit and foot), liver and abdominal cavity of transgenic green fluorescence protein (GFP) nude mice to establish RFP(+) /GFP(+) dual fluorescence solid tumor model. The re-cultured cells derived from implanted tumor tissues, SU3-RFP cells co-cultured with peritoneal fluid of transgenic GFP nude mice and malignant ascites of tumor-bearing mice were observed by fluorescence microscopy and real-time video image tracing to analyze the microenvironment of immune tolerance mediated by RFP(+) /GFP(+) implanted tumor. Results: Dual fluorescence labeled frozen section showed that all of cells in the tumor microenvironment were GFP(+) , while the pressed tissue-patch showed that the tumor blood vessels exhibited a RFP(+) /GFP(+) double-positioning yellow. In the GFP single fluorescence labeled tumor tissue, all of cells in the microenvironment were green, including tumor edge, necrotic foci and blood vessel. Among them, CD68(+) , F4/80(+) , CD11c(+) , CD11b(+) and CD80(+) cells were observed. In the dual fluorescence labeled co-cultured cells, the phagocytosis and fusion between green host cells and red tumor cells were also observed, and these fusion cells might transfer to the malignant dendritic cells and macrophages. Conclusions: The tumor microenvironment of immune tolerance induced by GSC is not affected by the tissue types of tumor-inoculated sites, and the immune tolerance mediated by inflammatory cells is associated with the inducible malignant transformation, which may be driven by cell fusion.

A genomewide association study of feed efficiency and feeding behaviors at two fattening stages in a White Duroc × Erhualian F population

Feeding efficiency is a multifactorial and economically important trait in pigs. Genetic improvement of feeding efficiency will greatly benefit the pig industry. In the past decades, the hog market weight has increased worldwide. However, whether the genetic architecture of feeding efficiency is same or not at early and late fattening periods is unclear. To map genomic regions for feed efficiency and feeding behavior traits at early (n ≥ 384) and late (n ≥ 334) growth stages in pigs, we performed genomewide association studies for feed to gain ratio (FCR), residual feed intake (RFI), daily feed intake, daily visit times, daily feeding time (DFT), feed intake per second (FIPS), and feed intake per visit during 3 periods (2 stages and overall) in a White Duroc × Erhualian F2 intercross population. Six chromosomal regions showed significant association with these traits, of which 4 loci were reported for the first time. Our results confirmed the QTL of FCR around 34 Mb on SSC7 and RFI around 134 Mb on SSC12. Of note, 2 regions were associated with more than 1 trait. One was around 36 Mb on SSC7, and there were 47 and 67 SNP associated with FCR from 120 to 210 and from 120 to 240 d, respectively. The top SNP is located in a 2.88-Mb linkage disequilibrium (LD) block that harbors 44 genes. We propose the high mobility group AT-hook 1 gene as a plausible candidate gene in this region. The other was evidenced around 53 Mb on SSC12, which had multiple association signals for DFT and FIPS. The top SNP is located in a 211-kb LD block that harbors only 1 annotated gene, WSCD1, which encodes a protein with sulfotransferase activity and involves the glucose metabolism and, therefore, appears to be a plausible candidate gene. Except the region on SSC12 associated with DFT at both stages, the rest of the regions associated with the traits at only 1 stage, so the genetic architectures of the 2 stages are not same.

GENOME-WIDE MAPPING OF COPY NUMBER VARIATIONS IN COMMERCIAL HYBRID PIGS USING A HIGH-DENSITY SNP GENOTYPING ARRAY

Copy number variations (CNVs) are important forms of structural variation in human and animals and can be considered as a major genetic component of phenotypic diversity. Here we used the Illumina PorcineSNP60 BeadChip V2 and a DLY [Duroc x (Large White x Landrace)] commercial hybrid population to identify 272 CNVs belonging to 165 CNV regions (CNVRs), of which 66 are new. As CNVRs are specific to origin of population, our DLY-specific data is an important complementary to the existing CNV map in the pig genome. Eight CNVRs were selected. for validation by quantitative real-time PCR (qRT-PCR) and the accurate rate was high (87.25%). Gene function analysis suggested that a common CNVR may play an important role in multiple traits, including growth rate and carcass quality.

Carrier Mobility Enhancement of Tensile Strained Si and SiGe Nanowires via Surface Defect Engineering

Changes in the carrier mobility of tensile strained Si and SiGe nanowires (NWs) were examined using an electrical push-to-pull device (E-PTP, Hysitron). The changes were found to be closely related to the chemical structure at the surface, likely defect states. As tensile strain is increased, the resistivity of SiGe NWs deceases in a linear manner. However, the corresponding values for Si NWs increased with increasing tensile strain, which is closely related to broken bonds induced by defects at the NW surface. Broken bonds at the surface, which communicate with the defect state of Si are critically altered when Ge is incorporated in Si NW. In addition, the number of defects could be significantly decreased in Si NWs by incorporating a surface passivated Al2O3 layer, which removes broken bonds, resulting in a proportional decrease in the resistivity of Si NWs with increasing strain. Moreover, the presence of a passivation layer dramatically increases the extent of fracture strain in NWs, and a significant enhancement in mobility of about 2.6 times was observed for a tensile strain of 5.7%.

Effects of surface chemical structure on the mechanical properties of Si(1-x)Ge(x) nanowires

The Young's modulus and fracture strength of Si(1-x)Ge(x) nanowires (NWs) as a function of Ge concentration were measured from tensile stress measurements. The Young's modulus of the NWs decreased linearly with increasing Ge content. No evidence was found for a linear relationship between the fracture strength of the NWs and Ge content, which is closely related to the quantity of interstitial Ge atoms contained in the wire. However, by removing some of the interstitial Ge atoms through rapid thermal annealing, a linear relationship could be produced. The discrepancy in the reported strength of Si and Ge NWs between calculated and experimented results could be related to SiO(2-x)/Si interfacial defects that are found in Si(1-x)Ge(x) NWs. It was also possible to significantly decrease the number of interfacial defects in the NWs by incorporating a surface passivated Al2O3 layer, which resulted in a substantial increase in fracture strength.

Validation of a paternally imprinted QTL affecting pH24h distinct from PRKAG3 on SSC15

We previously performed a genome scan in a White Duroc × Erhualian F(2) population and identified a QTL on SSC15 with strong effect on pH24h in M. Longissimus dorsi and M. Semimembranous muscle tissue. At that time, the mode of inheritance of this QTL was not clarified, and it was also unclear whether the observed QTL effect was completely or partially caused by mutations in the PRKAG3 gene, which is the only major gene on SSC15 so far known to influence pH24h. In this study, effects of the PRKAG3 gene on meat quality traits were estimated by association analyses. Two substitutions in PRKAG3, p.Ile199Val (p.I199V) and p.Thr30Asn (p.T30N), were found to be segregating in the F(2) population and to significantly affect pH24h and total glycogen in meat, respectively. However, we excluded PRKAG3 as a causative gene for the detected QTL based on the following reasons: (i) the gene was located outside of the QTL confidence interval; (ii) when the PRKAG3 substitution was included as a fixed effect in the QTL model, the F-ratio for the QTL increased rather than decreased; (iii) favourable alleles for pH24h at the QTL and at the PRKAG3 p.I199V locus originated from Erhualian and White Duroc founders, respectively; (iv) more importantly, this QTL showed exclusive maternal expression, differing from the Mendelian expression of PRKAG3. In conclusion, this study is the first to report a maternally-expressed QTL for pH24h on SSC15, which is distinct from PRKAG3.

Mapping quantitative trait loci for feed consumption and feeding behaviors in a White Duroc x Chinese Erhualian resource population

To identify QTL for feed consumption and feeding behavior traits in pigs, ADFI, feed conversion ratio (FCR), number of visits to the feeder per day (NVD), and average feeding rate (AFR) were recorded in 577 F(2) animals from a White Duroc x Chinese Erhualian resource population during the fattening period of 120 to 240 d. A whole genome scan was performed with 183 microsatellites covering the pig genome across the entire resource population. A total of 8 QTL were identified on 5 pig chromosomes, including 3 genome-wide significant QTL for FCR on SSC2, 7, and 9, 1 significant QTL for ADFI on SSC3, and 1 for NVD on SSC7. These QTL were identified for the first time, except for the QTL for FCR on SSC2. Four of the 5 significant QTL were adjacent to the known QTL for growth, carcass, and fat deposition traits, supporting the existence of gene(s) with pleiotropic effects on these traits. White Duroc alleles were generally associated with greater phenotypic values, except for those on SSC7 and 9. Comparison of QTL for feed consumption and feeding behaviors indicated that distinct chromosomes had effects on the 2 types of traits. Characterization of causative gene(s) underlying the identified QTL would shed new light on the genetic basis of feed consumption and feeding behaviors in pigs.

Polynitroxylated starch/TPL attenuates cachexia and increased epithelial permeability associated with TNBS colitis

Free radicals play an important role in the initiation and progression of inflammatory bowel disease (IBD). Therefore, the reduction or elimination of adverse oxidant effects can provide novel therapy for IBD. Here, the antioxidant capacity and protective effects of a new class of chemically modified hetastarch (polynitroxyl starch, or PNS) plus 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl (Tempol or TPL) (PNS/TPL) were assessed in a model of colitis. The superoxide scavenging capacity of PNS/TPL-that is, the inhibition of the reduction of cytochrome c in the presence of xanthine/xanthine oxidase (X/XO)-was evaluated in vitro. The effects of PNS/TPL on X/XO-induced neutrophil endothelial adhesion in vitro were investigated. Also, this study tested the protection produced by PNS/TPL in a mouse model of trinitrobenzene sulfonic acid (TNBS)-induced colitis. PNS/TPL was given intravenously immediately before (< 30 min) and intraperitoneally at 24 and 72 hr after TNBS induction. The body weight and survival rate of the mice were checked daily. Colonic mucosal damage was assessed on the 7th day by measuring intestinal permeability to Evans blue (EB) in vivo. The ability of PNS to reoxidize bioreduced TPL was documented by whole-body electron paramagnetic resonance (EPR) detection. We found that PNS or TPL exhibits superoxide dismutase (SOD)-like activity, with approximately 2% of SOD activity occurring on a molar basis. The endothelial-neutrophil adherence induced by X/XO was significantly inhibited by PNS/TPL but not by TPL alone. PNS/TPL protected against cachexia and mortality, both usually induced by TNBS. Epithelial permeability was increased significantly in TNBS mice but was ameliorated by the administration of PNS/TPL. In conclusion, PNS/TPL may be beneficial in the treatment or prevention of IBD through its antioxidant effects, which inhibit oxidant-mediated leukocyte adhesion and injury to endothelial cells.

Obstructed intestine as a reservoir for systemic infection

Intestinal motility, absorption, and secretion are altered after intestinal obstruction, but at what point the normal bacterial barrier function of the viable gut fails after intestinal obstruction is unclear. Thus, we tested whether after simple intestinal obstruction bacteria would translocate across the viable intestinal wall to cause systemic infection. Within 6 hours of intestinal ligation 1 cm proximal or distal to the ileocecal valve, bacteria had translocated to the mesenteric lymph nodes, and by 24 hours after intestinal obstruction, bacteria had spread to the liver, spleen, and blood stream. Bacterial translocation rarely occurred in the animals undergoing laparotomy and sham intestinal ligation, indicating that bacterial translocation was not due to surgical stress. Based on the results of these studies, bacterial translocation induced by intestinal obstruction appears to be due to disruption of the ecology of the normal gut microflora, leading to intestinal overgrowth with certain enteric bacilli and mucosal damage. Although the exact mechanism(s) by which simple mechanical obstruction injures the intestine is not known, the fact that mucosal injury did not occur in germ-free mice suggests that bacteria may play a role in the pathogenesis of obstruction-induced intestinal injury.

Lethal burn-induced bacterial translocation: role of genetic resistance

Since genetic factors may influence outcome after trauma or during infection, the current experiments were performed to examine the resistance of three genetically different mouse strains to burn-induced bacterial translocation. Outbred ICR, inbred Balb/c, and inbred C57/B1 mice, with a normal or disrupted (monoassociated with Escherichia coli C25) GI tract microflora, were subjected to sham or actual 25% body burns. In Balb/c, but not ICR mice, replacing the normal intestinal microflora with E. coli C25 converted the thermal injury from a nonlethal (0% mortality) to a lethal (68% mortality) injury. The increased mortality of the burned Balb/c mice monoassociated with E. coli C25 was associated with a higher incidence (p less than 0.05) and magnitude (p less than 0.05) of E. coli C25 translocation from the GI tract. The C57/B1 mice were intermediate between the Balb/c and ICR strains, in that C57/B1 mice monoassociated with E. coli C25 had a higher mortality and greater E. coli C25 translocation than mice with a normal microflora after thermal injury. Thus the composition of the intestinal microflora as well as the genetic background of the host influence the susceptibility of the host to burn-induced bacterial translocation and survival.

Genetic susceptibility to mucosal damage leads to bacterial translocation in a murine burn model

Since genetic factors may be important in host resistance to infections after thermal injury, we screened the susceptibility of three mouse strains (CD-1, Balb/c, and C57/bl) to thermally induced bacterial translocation from the GI tract. Bacteria translocated to the MLNs of Balb/c but not the CD-1 or C57/bl mice receiving 25% body burns. The increased incidence of bacterial translocation in the burned Balb/c mice appeared to be due to a burn-induced gut mucosal injury, since the intestinal mucosa of the Balb/c but not the CD-1 or C57/bl mice was damaged 24 hr after the thermal injury. The mucosal injury appears to be mediated, at least in part, by xanthine oxidase-generated oxygen-free radicals, since inhibition of xanthine oxidase activity with allopurinol, or inactivation of xanthine oxidase activity by a molybdenum-free tungsten diet, prevented the mucosal injury and reduced the extent of bacterial translocation.

Hemorrhagic shock-induced bacterial translocation is reduced by xanthine oxidase inhibition or inactivation

Experiments were performed to determine whether bacterial translocation (BT) after hemorrhagic shock is due to a reperfusion injury mediated by xanthine oxidase-derived oxidants. Rats were subjected to 30 minutes of shock (30 mm Hg) followed by reinfusion of shed blood. Twenty-four hours after hemorrhage and reinfusion, the mesenteric lymph node, liver, and spleen were harvested from each animal for bacterial culture, and the ileum and cecum were examined histologically. Sham-shocked (control) rats were instrumented, but blood was not withdrawn. The incidence of BT was higher in the shocked rats (61%) than in the sham-shocked animals (7%) (p less than 0.01). Allopurinol (50 mg/kg, administered orally), a competitive inhibitor of xanthine oxidase, reduced the incidence of shock-induced BT to 14% (p = 0.02). Similarly, rats fed a tungsten-supplemented molybdenum-free diet, which inactivates xanthine oxidase, reduced shock-induced BT to 10% (p = 0.02). The histologic damage cause by hemorrhagic shock was prevented by blocking xanthine oxidase activity. Thus hemorrhagic shock-induced bacterial translocation from the gut appears to be mediated by oxidants generated by activation of the xanthine oxidase system.