Hepatocyte inflammation model for cytotoxicity research: fructose or glycolaldehyde as a source of endogenous toxins

Insulin resistance and hepatotoxicity induced in high fructose fed rats may involve fructose derived endogenous toxins formed by inflammation. Thus fructose was seventy-fold more toxic if hepatocytes were exposed to non-toxic levels of hydrogen peroxide (H(2)O(2)) released by inflammatory cells. This was prevented by iron (Fe) chelators, hydroxyl radical scavengers, and increased by Fe, copper (Cu) or catalase inhibition. Fructose or glyceraldehyde/dihydroxyacetone metabolites were oxidized by Fenton radicals to glyoxal. Glyoxal (15 microM) cytotoxicity was increased about 200-fold by H(2)O(2). Glycolaldehyde was enzymically formed from glyceraldehyde, the fructokinase/aldolase B product of fructose. Glycolaldehyde cytotoxicity was increased 20-fold by H(2)O(2). The oxidative stress cytotoxicity induced was attributed to the Fenton oxidation of glycolaldehyde forming glycolaldehyde radicals and glyoxal, since cytotoxicity was prevented by aminoguanidine (glyoxal trap) or Fenton inhibitors. Glyoxal was also the Fenton product responsible for glycolaldehyde protein carbonylation as carbonylation was prevented by aminoguanidine or Fenton inhibitors.

Over-expression of SOCS-3 gene promotes IL-10 production by JEG-3 trophoblast cells

Suppressor of cytokine signaling-3 (SOCS-3) plays an important role in negative regulation of inflammatory response. Evidence has shown that SOCS-3 and IL-10 expressions were significantly reduced in placental trophoblasts from preeclampsia. IL-10 is an anti-inflammatory cytokine. In this study, we sought to determine if enhance SOCS-3 expression could affect IL-10 production in placental trophoblasts. Placental JEG-3 cells were used. Over-expression of SOCS-3 was generated by transfection of JEG-3 cells with a green fluorescent protein (GFP) tagged SOCS-3 gene, SOCS-3/ZsGreen1, by siPORT lipid transfection. Cells transfected with ZsGreen1 vector only was used as control. Our results showed that IL-6 production was reduced in cells over-expressed with SOCS-3. Moreover, SOCS-3 transfected cells produced more IL-10 when stimulated with IL-6. The increased IL-10 production by JEG-3 cells was in a dose-dependent manner, p<0.05. Our data suggested that enhanced SOCS-3 gene expression could promote IL-10 production by placental trophoblast cells, suggesting that SOCS-3 may play an important role in regulation of cytokine induced anti-inflammatory response in placental trophoblasts.

Altered interleukin-6 receptor, IL-6R and gp130, production and expression and decreased SOCS-3 expression in placentas from women with pre-eclampsia

Interleukin-6 (IL-6) and its receptor complex, IL-6 receptor (IL-6R) and gp130, are critical in induction of suppressor of cytokine signalling-3 (SOCS-3) protein, a negative cytokine regulator and anti-inflammatory mediator, in a biological system. Increased inflammatory response is believed to contribute to the placental dysfunction in pre-eclampsia (PE). However, it is not known if altered IL-6 receptor signalling and decreased SOCS-3 expression occur in placentas from PE. To study this, we examined IL-6, soluble IL-6R (sIL-6R) and soluble gp130 (sgp130) production by villous tissue from normal and PE placentas. Hypoxia effects on IL-6, sIL-6R and sgp130 production was determined. IL-6R, gp130 and SOCS-3 expression were determined by immunohistochemical staining and by Western blot. Our results showed that under normoxic conditions (21% O(2)), villous tissue from PE placentas produced relative more sgp130, but significantly less IL-6 and sIL-6R (p<0.01) than normal placental tissue. The ratio of sgp130/sIL-6R release was significantly higher by PE placentas than normal placentas, p<0.01. Under hypoxic conditions (2% O(2)), IL-6 production was significantly reduced by both normal (p<0.01) and PE (p<0.05) placental tissue. Hypoxia promoted sgp130 release by normal, but not by PE, placental tissue. Reduced IL-6R and SOCS-3 immunostaining and expression were found in PE placentas. We concluded that increased ratio of sgp130/sIL-6R production and/or reduced sIL-6R production combined with down-regulation of IL-6R and SOCS-3 expression in trophoblasts may lead to less cytokine inhibitory activity in PE placentas, which may account for the increased placental inflammatory response in PE.

Fructose and carbonyl metabolites as endogenous toxins

Dietary fructose consumption is one of the environmental factors contributing to the development of obesity and a fatty liver (hepatic steatosis). A two-hit hypothesis has been proposed for progression of hepatic steatosis to the more serious non-alcoholic steatosis (NASH), with the first hit being hepatic steatosis, and the second hit being inflammation and associated oxidative stress caused by reactive oxygen species (ROS) formation. As well, fructose-fed rats develop insulin resistance and serum levels of methylglyoxal, a glycolytic metabolite, are increased. Previously we reported that glyoxal-induced hepatocyte cytotoxicity could be attributed to mitochondrial toxicity as mitochondrial membrane potential was decreased and cytotoxicity was increased several orders of magnitude by low non-cytotoxic doses of H(2)O(2) (hepatocyte inflammation model). In this study, we have assessed the toxicity of fructose towards hepatocytes and investigated the molecular cytotoxic mechanisms involved. Fructose itself was only toxic at 1.5M, whereas 12 mM caused 50% cell death in 2h if the hepatocytes were exposed to a non-cytotoxic dose of H(2)O(2) continuously generated by glucose and glucose oxidase. The cytotoxic mechanism involved oxidative stress as ROS and H(2)O(2) formation preceded cytotoxicity, and cytotoxicity was prevented by radical scavengers, lipid antioxidants and ROS scavengers. It is proposed that the highly potent Fenton derived ROS catalyse the oxidation of fructose and particularly its carbonyl metabolites glycolaldehyde, dihydroxyacetone, glyceraldehyde. The carbon radicals and glyoxal formed compromise the cell's resistance to H(2)O(2).

Effect of pre-freezing conditions on semen cryopreservation in rhesus monkeys

Although sperm cryopreservation has been studied in at least 17 non-human primate species, systematic factor optimization for any single species is lacking. Gene banking of non-human primate sperm is still in its infancy. The objective of the present study was to initiate a systematic approach to optimize the process of sperm cryopreservation for rhesus macaques, specifically, factors related to pre-freezing conditions (e.g., straw freezing position, sperm concentration, sperm washing, equilibration methods, and equilibration time periods). Straw position had no effect on post-thaw motility (P=0.193). Sperm concentration was tested in a range from 5 x 10(6)mL(-1) to 5 x 10(8)mL(-1); post-thaw motility of sperm samples frozen at 5 x 10(7)cell mL(-1) (51.0+/-10.6%; mean+/-S.D.) and 5 x 10(8)cell mL(-1) (48.1+/-7.3%) were higher than samples frozen at 5 x 10(6)cells mL(-1) (33.0+/-12.0%, P=0.003). Comparison of motility immediately after thawing between samples with (51.2+/-6.2%) and without washing (53.9+/-6.8%) revealed no differences (P>0.05). However, washing improved sperm forward progression within 1h after thawing, whereas unwashed sperm retained higher post-thaw motility and progression during extended incubation (4h) after thawing (P<0.05). Equilibration methods (with or without pre-cooling) made no difference on post-thaw motility (P>0.05), and the most effective equilibration time was the duration required for samples to acclimate to 4 degrees C prior to freezing. Evaluation and optimization of these pre-freezing conditions will help to minimize sources of injury, maximize survival, and contribute to the development of an optimized cryopreservation protocol for rhesus macaque sperm.

New global communication process in thermodynamics: impact on quality of published experimental data

Thermodynamic data are a key resource in the search for new relationships between properties of chemical systems that constitutes the basis of the scientific discovery process. In addition, thermodynamic information is critical for development and improvement of all chemical process technologies. Historically, peer-reviewed journals are the major source of this information obtained by experimental measurement or prediction. Technological advances in measurement science have propelled enormous growth in the scale of published thermodynamic data (almost doubling every 10 years). This expansion has created new challenges in data validation at all stages of the data delivery process. Despite the peer-review process, problems in data validation have led, in many instances, to publication of data that are grossly erroneous and, at times, inconsistent with the fundamental laws of nature. This article describes a new global data communication process in thermodynamics and its impact in addressing these challenges as well as in streamlining the delivery of the thermodynamic data from "data producers" to "data users". We believe that the prolific growth of scientific data in numerous and diverse fields outside thermodynamics, together with the demonstrated effectiveness and versatility of the process described in this article, will foster development of such processes in other scientific fields.

Subzero water permeability parameters and optimal freezing rates for sperm cells of the southern platyfish, Xiphophorus maculatus

This study reports the subzero water transport characteristics (and empirically determined optimal rates for freezing) of sperm cells of live-bearing fishes of the genus Xiphophorus, specifically those of the southern platyfish Xiphophorus maculatus. These fishes are valuable models for biomedical research and are commercially raised as ornamental fish for use in aquariums. Water transport during freezing of X. maculatus sperm cell suspensions was obtained using a shape-independent differential scanning calorimeter technique in the presence of extracellular ice at a cooling rate of 20 degrees C/min in three different media: (1) Hanks' balanced salt solution (HBSS) without cryoprotective agents (CPAs); (2) HBSS with 14% (v/v) glycerol, and (3) HBSS with 10% (v/v) dimethyl sulfoxide (DMSO). The sperm cell was modeled as a cylinder with a length of 52.35 microm and a diameter of 0.66 microm with an osmotically inactive cell volume (Vb) of 0.6 V0, where V0 is the isotonic or initial cell volume. This translates to a surface area, SA to initial water volume, WV ratio of 15.15 microm(-1). By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the best fit membrane permeability parameters (reference membrane permeability to water at 0 degrees C, Lpg or Lpg [cpa] and the activation energy, E(Lp) or E(Lp) [cpa]) were found to range from: Lpg or Lpg [cpa] = 0.0053-0.0093 microm/minatm; E(Lp) or E(Lp) [cpa] = 9.79-29.00 kcal/mol. By incorporating these membrane permeability parameters in a recently developed generic optimal cooling rate equation (optimal cooling rate, [Formula: see text] where the units of B(opt) are degrees C/min, E(Lp) or E(Lp) [cpa] are kcal/mol, L(pg) or L(pg) [cpa] are microm/minatm and SA/WV are microm(-1)), we determined the optimal rates of freezing X. maculatus sperm cells to be 28 degrees C/min (in HBSS), 47 degrees C/min (in HBSS+14% glycerol) and 36 degrees C/min (in HBSS+10% DMSO). Preliminary empirical experiments suggest that the optimal rate of freezing X. maculatus sperm in the presence of 14% glycerol to be approximately 25 degrees C/min. Possible reasons for the observed discrepancy between the theoretically predicted and experimentally determined optimal rates of freezing X. maculatus sperm cells are discussed.

Extent of white matter lesions is related to acute subcortical infarcts and predicts further stroke risk in patients with first ever ischaemic stroke

OBJECTIVE

To investigate whether the extent of white matter lesions (WML) on fluid attenuated inversion recovery (FLAIR) MRI sequences is an independent risk factor for recurrent stroke, and to document the pattern of acute cerebral infarcts using diffusion weighted imaging (DWI) in patients with different severities of WML.

METHODS

In a prospective cohort study, 228 consecutive stroke patients were studied between 1999 and 2001 in a community hospital. The severity of WML was graded as 0 (no WML), 1 (mild), 2 (moderate), or 3 (severe) according to the FLAIR appearances. DWI was used to document the location and size of the infarct.

RESULTS

31 patients had grade 0 WML, 69 had grade 1, 59 had grade 2, and 69 had grade 3. Age was independently associated with WML on logistic regression analysis (p = 0.0001). Acute cerebral infarcts in deep white matter were correlated with increasing severity of WML. On a median follow up of 23.0 months, life table analysis showed that recurrent stroke was related to the severity of WML (recurrence rate 7.8% in grade 0, 9.3% in grade 1, 17.7% in grade 2, 43.7% in grade 3; p = 0.0001). Survival was reduced in patients with severe WML (p = 0.0068). A Cox proportional hazards model showed WML to be predictive of recurrent stroke (p = 0.000, hazard ratio = 4.177 (95% confidence interval, 2.038 to 8.564)) and also for survival (p = 0.040, hazard ratio = 2.021 (1.032 to 3.960)).

CONCLUSIONS

Patients with severe leukoaraiosis have increased risk of deep subcortical stroke and a higher risk of recurrent stroke.

Diffusion tensor imaging of the brain: review of clinical applications

We review the theoretical background to diffusion tensor imaging (DTI) and some of its commoner clinical applications, such as cerebral ischemia, brain maturation and traumatic brain injury. We also review its potential use in diseases such as epilepsy, multiple sclerosis, and Alzheimer's disease. The value of DTI in the investigation of brain tumors and metabolic disorders is assessed.

[Studies on liver cancer induced by non-necrotizing dose of diethylnitrosamine in rats]

OBJECTIVE

To provide an appropriate animal model of liver cancer and sensitive indicator for carcinogen risk assessment.

METHODS

The developmental processes of liver cancers in rats initiated by non-necrotizing dose of diethylnitrosamine and promoted by phenobarbital were studied.

RESULTS

Most of the preneoplastic lesions and liver cancers were made up of eosinophilic cells. The placental glutathione S-transferase (P-GST) staining could allow a lot of positive single cells, foci and nodules to be seen. But the lesions showed by HE staining expressed higher proliferating cell nuclear antigen (PCNA) than those showed by P-GST staining expressed, indicating a greater possibility for these lesions to persist and develop further. The cellular morphologic analysis demonstrated that the ratio of nuclear radii to cytoplasm radii decreased in the cell in PCNA positive expressing nodules. In addition, the nodules showed by P-GST expressed higher PCNA than those the foci expressed, indicating an increased possibility to develop further in the nodules.

CONCLUSION

PCNA expression may be used as a relatively ideal marker for predicting the potential development of precancerous lesions in the experimental model of rat liver cancer induction.

[Study on effect of qingkailing injection and its active principle in inducing cell apoptosis in human acute promyelocytic leukemia]

OBJECTIVE

To investigate the mechanism of Qingkailing (QKL) Injection in treating acute promyelocytic leukemia.

METHODS

Using MTT technique, cell morphologic method, DNA gel electrophoresis and flow-cytometry to study the human acute promyelocytic leukemia (HL-60) cell apoptosis induced by QKL and its active principle.

RESULTS

QKL and its active principle, Baicalin and hyodeoxycholic acid, showed strong cytotoxicity in inhibiting HL-60 cell, the Bezoar cholic acid showed a weaker effect. Apoptosis could be induced after being treated for 6 hrs by the former three principles, showing a typical apoptosis peak under flow-cytometry, but could not be induced by the latter one.

CONCLUSION

QKL could induce leukemia cell apoptosis in vitro, which may be one of the mechanisms of QKLI in curing acute promyelocytic leukemia.

Overexpression of the A1 adenosine receptor in adipose tissue protects mice from obesity-related insulin resistance

In-vitro studies have implicated the A(1) adenosine receptor (A(1)AR) of adipocytes in inhibition of lipolysis, stimulation of lipogenesis and enhancement of the action of insulin on glucose metabolism. To determine whether any of these activities were physiologically relevant in an intact animal, A(1)AR was overexpressed in adipose tissue of transgenic mice. Lower plasma free fatty acid (FFA) levels were observed in the transgenic mice relative to the litter-matched controls, supporting a significant physiological role for adipocyte A(1)AR in the control of lipolysis. However, no differences were observed in body weights or body composition. On a high fat diet, both the transgenic mice and the litter matched controls, male and female, became equally obese. Unlike the control mice, however, the transgenic mice did not develop insulin resistance, as demonstrated by serum glucose and insulin levels and glucose and insulin tolerance tests. These findings demonstrate that adipocyte A(1)AR plays an important physiological role in the control of insulin sensitivity in an intact animal and therefore should be considered to be a potential therapeutic target for the treatment of obesity-related insulin resistance and type 2 diabetes.

Characterization of a calcium-activated chloride channel as a shared target of Th2 cytokine pathways and its potential involvement in asthma

Interleukin (IL)-9 is a T helper (Th) 2 cytokine recently implicated as an essential factor in determining susceptibility to asthma. Transgenic mice overexpressing IL-9 exhibit many features that are characteristic of human asthma. To better understand the mechanism by which IL-9 mediates the various biologic activities in asthma, we performed suppressive subtraction hybridization with whole lung from IL-9 transgenic and control mice. Here we report the identification of mCLCA3, a calcium-activated chloride channel that was specifically induced in the lung epithelium of IL-9 transgenic mice. Expression of mCLCA3 could also be induced by intratracheal administration of IL-9 or other Th2 cytokines (IL-4, IL-13), but not by interferon-gamma. Moreover, expression of mCLCA3 was induced in the lung of antigen-exposed mice, and this induction could be suppressed by neutralizing IL-9 antibody treatment, indicating IL-9 is both necessary and sufficient to induce mCLCA3 in this experimental model of asthma. Finally, we demonstrate that hCLCA1 is the human counterpart to mCLCA3 and is also induced in vitro in human primary lung cells by Th2 cytokine treatment. Together, these data strongly implicate the involvement of mCLCA3 (in mice) and hCLCA1 (in humans) in the pathogenesis of Th2 cytokine-mediated asthmatic disorders.

Neutrophil-mediated epithelial injury during transmigration: role of elastase

Neutrophil-mediated injury to gut epithelium may lead to disruption of the epithelial barrier function with consequent organ dysfunction, but the mechanisms of this are incompletely characterized. Because the epithelial apical junctional complex, comprised of tight and adherens junctions, is responsible in part for this barrier function, we investigated the effects of neutrophil transmigration on these structures. Using a colonic epithelial cell line, we observed that neutrophils migrating across cell monolayers formed clusters that were associated with focal epithelial cell loss and the creation of circular defects within the monolayer. The loss of epithelial cells was partly attributable to neutrophil-derived proteases, likely elastase, because it was prevented by elastase inhibitors. Spatially delimited disruption of epithelial junctional complexes with focal loss of E-cadherin, beta-catenin, and zonula occludens 1 was observed adjacent to clusters of transmigrating neutrophils. During neutrophil transmigration, fragments of E-cadherin were released into the apical supernatant, and inhibitors of neutrophil elastase prevented this proteolytic degradation. Addition of purified leukocyte elastase also resulted in release of E-cadherin fragments, but only after opening of tight junctions. Taken together, these data demonstrate that neutrophil-derived proteases can mediate spatially delimited disruption of epithelial apical junctions during transmigration. These processes may contribute to epithelial loss and disruption of epithelial barrier function in inflammatory diseases.

Loss of annexin II heavy and light chains in prostate cancer and its precursors

Annexin II mRNA coding for a calcium binding protein was found to be absent in prostate cancer by subtractive hybridization and Northern analysis. In contrast to high expression in normal and benign hyperplastic glandular and basal epithelium, Annexin II heavy (p36) and light (p11) chains in 31/31 prostate cancer specimens were lost immunohistochemically. In glands involved by prostate intraepithelial neoplasia, 65% lost both chains in glandular epithelial cells, whereas basal cells were all positively stained. Southern analysis of cancer DNA showed no noticeable deletion in p36 gene. LNCaP cells treated with 5-azacytidine re-expressed p36, suggesting methylation could be responsible for the silencing.