Protective effects of bone morphogenetic protein 7 against amyloid-beta induced neurotoxicity in PC12 cells

Bone morphogenetic protein 7 (BMP7) has neuroprotective effects against ischemia, oxidation stress, and lipopolysaccharide, but its role on amyloid-beta (Aβ)-induced neurotoxicity in Alzheimer's disease (AD) and the underlying mechanisms remain unclear. In this study, we exposed PC12 cells to Aβ25-35 for 26 h to induce neurotoxicity, and added exogenous BMP7 at 2 h to observe the neuroprotective effects. The protective mechanisms involved, mostly related to inhibition of cell apoptosis and oxidation stress, were analyzed. In rat in vivo experiments, we bilaterally injected Aβ1-40 into the basal forebrain to simulate neuropathological processes in AD, performed the Morris water maze test to evaluate the effect of Aβ on spatial learning and memory, and explored the change of endogenous BMP7 expression in the brain. The present study demonstrated that BMP7 prevented neuronal injuries in PC12 cells induced by Aβ25-35, including cell apoptosis and morphological impairment of dendrites as well as oxidation stress. BMP7 treatment significantly protected PC12 cells against Aβ25-35-induced injury and inhibited the increasing content of the Bax gene and the decreasing activities of superoxide dismutase (SOD). Aβ1-40 bilaterally injected into the rat basal forebrain obviously inhibited the rat's spatial learning ability and memory, and significantly induced downregulation of endogenous BMP7 in the basal forebrain while upregulating it in the hippocampus. Our results suggest that BMP7 has neuroprotective effects against Aβ, which may be mediated through inhibition of Bax gene expression during cell apoptosis and elevation of SOD activities during the oxidative stress response. On the other hand, endogenous BMP7 may have a potential self-modulation capacity through negative feedback between the region of the basal forebrain and the hippocampus as a protective cytokine.

High- and low-temperature manipulation during late incubation: effects on embryonic development, the hatching process, and metabolism in broilers

Temperatures continuously higher and lower than the standard incubation temperature by 3°C from embryonic d 16 until embryonic d 18.5 result in differential effects on embryonic development, the hatching process, and embryonic metabolism. Embryos in the high-temperature group were forced into a state of malnutrition by the temperature treatment, as reflected by reduced embryo growth and yolk consumption, resulting in a significantly lower chick weight at hatch. In addition, altered air cell and blood gases as well as a retarded hatching process further indicated reduced growth of embryos exposed to higher incubation temperatures during the latter part of incubation. In addition, hatchability was significantly reduced by the high-temperature treatment due to higher embryonic mortality during the treatment period and the hatching process. Levels of blood glucose, lactate, liver glycogen, plasma triglycerides, and nonesterified fatty acids indicated an altered carbohydrate and lipid metabolism for the high-temperature group. Although the hatching process of embryos exposed to lower incubation temperatures was also significantly retarded, their embryonic development and growth were strikingly similar to those of the control group.

The feasibility of light microscopic measurements of intercellular spaces in squamous epithelium in the lower-esophagus of GERD patients

The study aims to determine whether light microscopy can be used to accurately measure the diameters of intercellular spaces between squamous epithelial cells in the lower esophagus, and whether changes in this outcome measure can be used as a diagnostic marker for gastroesophageal reflux disease (GERD). The study has two parts. Part 1 involves 42 asymptomatic controls and 119 patients with typical symptoms of GERD, including 58 with erosive esophagitis (EE), and 61 patients with nonerosive gastroesophageal reflux disease (NERD). All biopsies were taken from the lower esophagus. All samples were observed using an immersion objective, after which diameters were measured by computer-assisted morphometry. Part 2 involves 61 individuals who were randomly selected from part 1, including 19 controls, 13 with NERD and 29 with EE. Diameter measurements using both light microscopy and transmission electron microscopy (TEM) were performed for samples of 61 individuals. Samples from a total of 61 individuals (31 male, 30 female, mean age 44.3 ± 16.0 years) were observed using both light microscopy and TEM. Both methods showed significant differences between control and disease groups; the outcomes from the two methods had a certain correlation (r = 0.605, P = 0.000). Morphometric analysis of all 161 individuals (83 males, 78 females, mean age 41.4 ± 15.7) showed mean diameters from light microscopy to be 0.58 ± 0.16 µm for controls, 1.07 ± 0.30 µm for NERD, and 1.29 ± 0.20 µm for EE; differences between control and disease groups were significant (P<0.05). The optimal cut-off value from receiver operator characteristic analysis was 0.85 µm. Diagnoses were validated using the combination of symptoms of GERD, endoscopy, and 24 h ambulatory pH monitoring as the gold standard. At the optimal cutoff, sensitivity was 93.3% and specificity was 100%. The diameters of the intercellular spaces in squamous epithelium of lower esophagus from controls and in patients with GERD can be quantitatively measured using light microscopy. Dilated diameters can serve as a sensitive, specific, and objective indicator for diagnosis of GERD.

Panax ginseng has anti-infective activity against opportunistic pathogen Pseudomonas aeruginosa by inhibiting quorum sensing, a bacterial communication process critical for establishing infection

Virulent factors produced by pathogens play an important role in the infectious process, which is regulated by a cell-to-cell communication mechanism called quorum sensing (QS). Pseudomonas aeruginosa is an important opportunistic human pathogen, which causes infections in patients with compromised immune systems and cystic fibrosis. The QS systems of P. aeruginosa use N-acylated homoserine lactone (AHL) as signal molecules. Previously we have demonstrated that Panax ginseng treatment allowed the animals with P. aeruginosa pneumonia to effectively clear the bacterial infection. We postulated that the ability to impact the outcome of infections is partly due to ginseng having direct effect on the production of P. aeruginosa virulence factors. The study explores the effect of ginseng on alginate, protease and AHL production. The effect of ginseng extracts on growth and expression of QS-controlled virulence factors on the prototypic P. aeruginosa PAO1 and its isogenic mucoid variant (PAOmucA22) was determined. Ginseng did not inhibit the growth of the bacteria, enhanced the extracellular protein production and stimulated the production of alginate. However, ginseng suppressed the production of LasA and LasB and down-regulated the synthesis of the AHL molecules. Ginseng has a negative effect on the QS system of P. aeruginosa, may explain the ginseng-dependent bacterial clearance from the animal lungs in vivo in our previous animal study. It is possible that enhancing and repressing activities of ginseng are mutually exclusive as it is a complex mixture, as shown with the HPLC analysis of the hot water extract. Though ginseng is a promising natural synergetic remedy, it is important to isolate and evaluate the ginseng compounds associated with the anti-QS activity.

Optical fiber microwire current sensor

We demonstrate a compact optical fiber microwire current sensor based on the Faraday effect with gigahertz frequency of current sensing capabilities.

Flk-1+ mesenchymal stem cells aggravate collagen-induced arthritis by up-regulating interleukin-6

The immunomodulatory ability of mesenchymal stem cells (MSCs) may be used to develop therapies for autoimmune diseases. Flk-1(+) MSCs are a population of MSCs with defined phenotype and their safety has been evaluated in Phase 1 clinical trials. We designed this study to evaluate whether Flk-1(+) MSCs conferred a therapeutic effect on collagen-induced arthritis (CIA), an animal model of rheumatic arthritis, and to explore the underlying mechanisms. Flk-1(+) MSCs, 1-2 x 10(6), were injected into CIA mice on either day 0 or day 21. The clinical course of arthritis was monitored. Serum cytokine profile was determined by cytometric bead array kit or enzyme-linked immunosorbent assay. Flk-1(+) MSCs and splenocytes co-culture was conducted to explore the underlying mechanisms. Flk-1(+) MSCs did not confer therapeutic benefits. Clinical symptom scores and histological evaluation suggested aggravation of arthritis in mice treated with MSCs at day 21. Serum cytokine profile analysis showed marked interleukin (IL)-6 secretion immediately after MSC administration. Results of in vitro culture of splenocytes confirmed that the addition of Flk-1(+) MSCs promoted splenocyte proliferation and increased IL-6 and IL-17 secretion. Moreover, splenocyte proliferation was also enhanced in mice treated with MSCs at day 21. Accordingly, MSCs at low concentrations were found to promote lipopolysaccharide-primed splenocytes proliferation in an in vitro co-culture system. We propose that Flk-1(+) MSCs aggravate arthritis in CIA model by at least up-regulating secretion of IL-6, which favours Th17 differentiation. When Flk-1(+) MSCs are used for patients, we should be cautious about subjects with rheumatoid arthritis.

A comparative study on the LDA + U and hybrid functional methods on the description of the electronic structure of YTiO3 under high pressure

The electronic structures of YTiO3 under pressure have been studied with LDA + U (local density approximation + Hubbard parameter) and hybrid functional methods. From matching the experimental band gaps, the Hubbard U and hybrid functional mixing parameters were determined. It is found that both parameters vary with the pressure. Analysis of the electronic structures indicates that the description of the chemical bonding is also dependent on the method of choice.

Laryngeal constriction during hypoxic gasping and its role in improving autoresuscitation in two mouse strains

Laryngeal closure following hypoxic gasps has been documented, but its efficacy in improving autoresuscitation capacity is unknown. We studied SWR/J mice who normally cannot autoresuscitate and the C57/BLJ strain who can. We evaluated the effects of elevated end-inspiratory lung volume immediately following a gasp. We compared upper airway-intact mice with tracheostomized mice in which the vocal cords are bypassed. We used the techniques of repeated autoresuscitate trials to test autoresuscitation capability. Both SWR/J and C57/BLJ mice could maintain elevated lung volume immediately after a gasp (breath holding). Such breath holding increased autoresuscitation ability in C57/BLJ mice but did not in SWR/J mice. In SWR/J mice, the duration of the breath holds was less than that in the C57/BLJ mice. These findings indicate that gasp-associated breath holding improves autoresuscitation capability during repeated autoresuscitation trials. Also, they show that SWR/J mice have a deficiency in central nervous system mechanisms regulating glottic closure during hypoxic gasping.

Immune responses and enhanced disease resistance in Chinese drum, Miichthys miiuy (Basilewsky), after oral administration of live or dead cells of Clostridium butyrium CB2

Clostridium butyrium CB2 isolated from chickens was tested as a potential fish probiotic in the Chinese drum, Miichthys miiuy. Fish were fed live (CB), dead CB2 (D-CB) cells (10(8) cells g(-1)) or spent culture supernatant (SCS), for 30 days and challenged with Vibrio anguillarum or Aeromonas hydrophila. Survival was higher in both the CB and the CB-D fed groups, but the SCS group was not significantly different from the control. After feeding live or dead CB2 cells, there was increase in phagocytic activity of the head kidney macrophages, the lysozyme activity of serum and gut mucosa and immunoglobulin (Ig) level. The SCS group showed no obvious change in immune parameters. The results suggest that live or dead Clostridium butyrium CB2 has an immunomodulatory effect on fish.

Expression and clinical significance of the stem cell marker CD133 in hepatocellular carcinoma

BACKGROUND

Although the primitive haematopoietic and neuronal stem cell marker CD133 is known to be present in cancer stem cells (CSCs) in hepatocellular carcinoma (HCC), the postresection prognostic impact of CD133 in HCC patients remains limited.

METHODS

Sixty-three resected specimens were collected from HCC patients. The expression of CD133 protein was analysed by immunohistochemistry and the association of CD133 expression with clinicopathological characteristics, tumour recurrence and survival of the patients was evaluated.

RESULTS

Immunohistochemical analysis of 63 HCC tissue specimens revealed that CD133 positive tumour cells were frequently present in HCC. Increased CD133 immunostaining was found in 26 specimens (41.3%). Increased CD133 expression levels were correlated with increased tumour grade, advanced disease stage, and elevated serum alpha-fetoprotein levels. Kaplan-Meier analysis indicated that patients with increased CD133 levels had shorter overall survival and higher recurrence rates compared with patients with low CD133 expression. Multivariate analyses revealed that increased CD133 expression was an independent prognostic factor for survival and tumour recurrence in patients with HCC.

CONCLUSIONS

These findings suggest that reactivated CD133 positive cells are frequently present in HCC. Additionally, increased CD133 expression corresponds with higher stage tumours in HCC, thus indicating a poor prognosis for patients. These data support the CSC hypothesis.

Role of bone marrow-derived cells in experimental chronic pancreatitis

BACKGROUND

Chronic pancreatitis is a known risk factor for pancreatic adenocarcinoma. Recent work has pointed to a role for bone marrow-derived progenitor cells (BMDCs) in chronic inflammation-based carcinogenesis. Consequently, the role of BMDCs in chronic pancreatitis was investigated.

METHODS

The fate of BMDCs was followed using green fluorescent protein and the Y chromosome as bone marrow markers in gender-mismatched transplanted mice treated with repeated injections of cerulein for up to 45 weeks. The phenotype of engrafted BMDCs was assessed based on the co-expression of bone marrow and pancreatic markers.

RESULTS

After 45 weeks of cerulein treatment, mice developed severe chronic pancreatitis but no preneoplastic lesions. BMDCs did engraft in the pancreas. Most of the BMDCs were desmin positive and contributed to 5.12% (1.12%) (mean (SEM)) of the pancreatic stellate cell population. Pancreatic stellate cells derived from the bone marrow could be activated, as demonstrated by alpha-smooth muscle actin expression, suggesting a role in tissue repair. BMDCs could also be found in pancreatic ducts, based on dolichos biflorus agglutinin and cytokeratin 19 stainings, but at a much lower frequency (0.62% (0.11%)).

CONCLUSION

BMDCs contribute to the pancreatic stellate cell population, suggesting a role in pancreatic tissue repair. In the absence of preneoplastic lesions, BMDCs contribute at a very low level to the ductal epithelium of the chronically inflamed pancreas. The role of BMDCs in pancreatic carcinogenesis remains to be defined.

Deregulated expression of Notch receptors in human hepatocellular carcinoma

BACKGROUND AND AIM

Notch signaling controls cellular differentiation and proliferation. Deregulated expression of Notch receptors is observed in a growing number of malignant tumours, however, the role of Notch signaling in hepatocellular carcinoma is still unknown. To address this, the expression of Notch receptors in human hepatocellular carcinoma was examined in both protein and ribonucleic acid levels.

PATIENTS AND METHODS

Fifty-three hepatocellular carcinoma tissue sections were detected by immunohistochemistry. Three paired fresh surgical hepatocellular carcinoma and adjacent nontumour liver samples were analyzed by Western blot and reverse transcriptase polymerase chain reaction. Immunohistochemistry, Western blot and reverse transcriptase polymerase chain reaction are reliable methods to examine the expression of protein and RNA.

RESULTS

All of the four Notch receptors were expressed in the neoplastic cells of hepatocellular carcinoma tissues with different intensity and extensity. Notch1 and Notch4 were expressed in both cytoplasm and nucleus, and all of the nuclear staining showed up in the cytoplasm-positive cases. Cytoplasmic and nuclear Notch1 was detected in 88.7% (47/53) and 9.4% (5/53) of hepatocellular carcinoma tissues, respectively; positive rates of Notch4 were 67.9% (36/53) in cytoplasm and 52.8% (31/53) in nucleus. Notch2 and Notch3 were only in cytoplasm, with positive rates of 26.4% (14/53) and 52.8% (28/53), respectively. Compared with adjacent nontumour liver, Notch1 (cytoplasmic) and Notch4 (nuclear) were up-regulated (P<0.05, P<0.05), Notch2 was down-regulated (P<0.05), while Notch1 (nuclear), Notch3 and Notch4 (cytoplasmic) showed no difference between hepatocellular carcinoma and adjacent nontumour liver. Western blot and reverse transcriptase polymerase chain reaction analysis showed a consistent result.

CONCLUSION

Our findings indicate that the expression of Notch receptors was deregulated and Notch signaling might be involved in the development of hepatocellular carcinoma.

Isolated oesophageal cyst connected with the bronchus

We report an unusual case of a patient with an oesophageal cyst connected to the bronchus. A 24-year old male with a two-year history of repeated attacks of chest infection and haemoptysis was found to have a cyst of 4 x 4 cm affecting the anterior and apical segments of the right upper lobe. The cyst was excised in its entirety and the histopathological study of the cyst showed stratified squamous epithelium with submucosal and muscular layer but no cartilage. The pathological diagnosis was an oesophageal cyst. No previous case of isolated oesophageal cyst connected to the bronchus has been reported according to the available literature.

Rapid eye movement sleep deprivation selectively impairs recall of fear extinction in hippocampus-independent tasks in rats

Previous studies have shown that rapid eye movement (REM) sleep deprivation (RSD) exerts a detrimental effect on some memory tasks. However, whether post-learning RSD impairs memory for fear extinction, an important model of inhibitory learning, remains to be elucidated. The present study examined the effects of post-extinction RSD from 0 to 6 h and 6 to 12 h on recall of fear extinction tested 24 h after extinction training. We found that RSD from 0 to 6 h significantly increased freezing when recall of extinction of cued fear was tested in the context in which rats received extinction training whereas RSD from 6 to 12 h had no effect (experiments 1 and 2, two hippocampus-independent memory tasks). RSD at either time point had no effect on freezing when recall of extinction of cued fear was tested in the context different from that in which extinction training occurred (experiment 3, a hippocampus-dependent memory task). Additionally, we observed no effect of RSD at either time point on freezing during recall test for extinction of contextual fear (experiment 4, a hippocampus-dependent memory task). These results suggest that the effects of post-extinction RSD on memory for fear extinction are complex. RSD impairs recall of fear extinction in hippocampus-independent tasks, but does not affect recall of fear extinction in hippocampus-dependent tasks. Our findings extend previous research on the effects of RSD on learning and memory and support the notion that REM sleep is involved in memory process of certain tasks.

Heavy metal contamination and distribution in the urban environment of Guangzhou, SE China

Ever-increasing heavy metal accumulation in the urban environment of Guangzhou, the largest light industrial production base and one of the most rapidly developing cities in China, poses a serious threat to environment as well as to human health in the region. As a sink or source, urban deposits are good indicators of the level and extent of heavy metal accumulation in the surface environment. The aim of this preliminary study was to examine the distribution of heavy metal contamination in the urban environment of Guangzhou. It was based on a systematic sampling of road dusts and corresponding gully sediments along major roads running mainly through commercial and residential to industrial districts of the city. In addition to road dusts and gully sediments, ceiling dusts from the Pearl River Tunnel were also collected to characterize anthropogenic emissions dominated by traffic-related activities. In general, the level of Cd, Cu, Pb and Zn contaminations were more severe on the industrialized side of Guangzhou than on the western side where heavy traffic and industrial activities were limited. The primary determinants of the level of heavy metal contamination and the distribution of this contamination in the urban environment of Guangzhou were the site-specific conditions of its urban setting, particularly the types of industries, the nature of the traffic flow, sample residence times and variations in grain size of the particulate contaminants. This study highlights the complexity of the urban system and indicates that in just such a system individual urban components should be interlinked to assess the long-term environmental and health effects of heavy metal contamination. Among the heavy metals tested--Cd, Cu, Pb and Zn--the level of Zn contamination was the most severe and widespread, and thus requires immediate attention.

Livin promotes Smac/DIABLO degradation by ubiquitin-proteasome pathway

Livin, a member of the inhibitor of apoptosis protein (IAP) family, encodes a protein containing a single baculoviral IAP repeat (BIR) domain and a COOH-terminal RING finger domain. It has been reported that Livin directly interacts with caspase-3 and -7 in vitro and caspase-9 in vivo via its BIR domain and is negatively regulated by Smac/DIABLO. Nonetheless, the detailed mechanism underlying its antiapoptotic function has not yet been fully characterized. In this report, we provide, for the first time, the evidence that Livin can act as an E3 ubiquitin ligase for targeting the degradation of Smac/DIABLO. Both BIR domain and RING finger domain of Livin are required for this degradation in vitro and in vivo. We also demonstrate that Livin is an unstable protein with a half-life of less than 4 h in living cells. The RING domain of Livin promotes its auto-ubiquitination, whereas the BIR domain is likely to display degradation-inhibitory activity. Mutation in the Livin BIR domain greatly enhances its instability and nullifies its binding to Smac/DIABLO, resulting in a reduced antiapoptosis inhibition. Our findings provide a novel function of Livin: it exhibits E3 ubiquitin ligase activity to degrade the pivotal apoptotic regulator Smac/DIABLO through the ubiquitin-proteasome pathway.

Decay of Loschmidt echo enhanced by quantum criticality

We study the transition of a quantum system from a pure state to a mixed one, which is induced by the quantum criticality of the surrounding system E coupled to it. To characterize this transition quantitatively, we carefully examine the behavior of the Loschmidt echo (LE) of E modeled as an Ising model in a transverse field, which behaves as a measuring apparatus in quantum measurement. It is found that the quantum critical behavior of E strongly affects its capability of enhancing the decay of LE: near the critical value of the transverse field entailing the happening of quantum phase transition, the off-diagonal elements of the reduced density matrix describing S vanish sharply.

Site of ATP and phenylephrine synergistic stimulation of vasopressin release from the hypothalamo-neurohypophyseal system

ATP and norepinephrine are neurotransmitters carrying cardiovascular information to vasopressin (AVP) neurones. As shown previously, exposure of hypothalamo-neurohypophyseal system explants to ATP and phenylephrine (PE) (alpha(1)-adrenergic agonist) causes a significantly larger increase in AVP release than with either agent alone and converts the response from a transient to a sustained stimulation of AVP release. Potential mechanisms for this synergism include presynaptic stimulation of excitatory afferent input (i.e. glutamate release), postsynaptic activation of receptors on AVP neurones, modulation of stimulus-secretion coupling in the neural lobe and/or involvement of glial/neuronal interactions. The response to ATP + PE (100 microM each) was not altered in the presence of either a cocktail of ionotropic glutamate receptor antagonists (CNQX + AP5) or a nonselective metabotropic glutamate receptor antagonist [(RS)-alpha-methyl-4-carboxyphenylglycine]. Thus, it is not dependent on activation of glutamate receptors. Treatment with tetrodotoxin (3 microM) eliminated the response to ATP + PE. Because this could reflect blockade of action potentials propagated from the AVP perikarya to the nerve terminals in the neural lobe or action potentials generated in the neural lobe directly, synergism in the neural lobe was addressed by perifusing isolated neural lobes with ATP and PE alone or together. Synergistic stimulation of AVP release by ATP + PE was not observed in isolated, perifused neural lobes. Thus, the synergistic effect persists in the absence of glutamate transmission, is not due to synergistic actions of P(2) and alpha(1)-adrenergic receptors occurring at the level of the neural lobe and requires action potentials in either the hypothalamus or neural lobe.

Suppression of tumor growth using a recombinant adenoviral vector carrying the dominant-negative mutant gene Survivin-D53A in a nude mice model

Survivin (SVV), an inhibitor of apoptosis protein, is found to be upregulated in many cancers. We previously demonstrated that a dominant-negative mutant SVV-D53A was able to induce apoptosis in a p53-independent manner. Here, we report the construction and characterization of a recombinant replication-deficient adenoviral vector encoding a human SVV-D53A gene for its effectiveness against tumor growth both in vitro and in vivo. Transfection of liver tumor cells QGY-7703 with Ad-SVV-D53A results in significant apoptosis as measured by an increase in sub-G1 DNA content, procaspase-9 activation and further downstream PARP-1 cleavage. Furthermore, animal studies using QGY-7703 liver carcinoma xenografts in nude mice revealed that treatment of QGY-7703 cells with dominant-negative SVV-D53A, but not with wild-type SVV-adenovirus, prevents tumor outgrowth, inhibits growth of established tumors and results in a notably improved survival advantages in xenograft studies. Both the transferase-mediated dUTP nick-end labeling assay and immunostaining experiment demonstrated that tumor growth inhibition is associated with apoptosis induced by SVV-D53A expression. Taken together, these data suggest that recombinant adenovirus Ad-SVV-D53A carrying a Survivin dominant-negative gene SVV-D53A promotes apoptosis-mediated tumor suppression and could potentially be a promising candidate for cancer therapies.

Akt inhibition upregulates FasL, downregulates c-FLIPs and induces caspase-8-dependent cell death in Jurkat T lymphocytes

In T lymphocytes, the role of Akt in regulating Fas/Fas ligand (FasL)-mediated apoptotic signaling and death is not clearly understood. In this study, we observed that inhibition of Akt causes enhanced expression of FasL mRNA and protein and increased death-inducing signaling complex (DISC) formation with Fas-associated death domain (FADD) and procaspase-8 recruitment. Also, caspase-8 was activated at the DISC with accompanying decrease in c-FLIPs expression. FasL neutralizing antibody significantly decreased apoptotic death in the Akt-inhibited T cells. Additionally, Akt inhibition-induced Fas signaling was observed to link to the mitochondrial pathway via Bid cleavage. Further, inhibition of caspase-8 activity effectively blocked the loss of mitochondrial membrane potential and DNA fragmentation, suggesting that DISC formation and subsequent caspase-8 activation are critical initiating events in Akt inhibition-induced apoptotic death in T lymphocytes. These data demonstrate yet another important survival function governed by Akt kinase in T lymphocytes, which involves the regulation of FasL expression and consequent apoptotic signaling.

Tumour necrosis factor receptor gene therapy affects cellular immune responses in collagen induced arthritis in mice

BACKGROUND

Collagen induced arthritis (CIA) is an animal model of rheumatoid arthritis (RA) amenable to immunotherapy directed against tumour necrosis factor alpha (TNFalpha).

OBJECTIVE

To evaluate whether local TNF receptor (TNF-R) gene therapy in DBA/1 mice exerts an influence beyond anti-inflammatory effects. Two measures of CIA pathogenesis were investigated-namely, immunity to collagen II (CII) 245-270 peptide (the major immunodominant epitope within bovine CII) and the preferential activation of T cell Vbeta8.2 variable region receptors in arthritic DBA/1 mice.

METHODS

DBA/1 mice received single periarticular injections of media or retroviral vectors containing LacZ or human TNF-R into affected arthritic paws at disease onset. Disease severity was monitored, immune responses towards the immunodominant bovine CII 245-270 and subdominant CII 334-360 peptide epitopes were assessed by ELISA, and T cell Vbeta usage was analysed by real time polymerase chain reaction for the LacZ transduced, TNF-R, and viral-free media treated control animals. The therapeutic influence of TNF-R gene transduction was compared with other groups at different times after treatment.

RESULTS

Reduced disease severity was seen 15-35 days after treatment, with a concomitant increase in immunity towards the subdominant CII 334-360 peptide epitope rather than the immunodominant CII 245-270 peptide in TNF-R treated animals. Early in the disease, TNF-R treated animals demonstrated a reduction of bias towards the otherwise predominant Vbeta8.2 T cell subset.

CONCLUSIONS

TNF-R gene therapy influences cellular immunity in CIA, leading to overall disease amelioration, thus suggesting that TNF inhibition may have therapeutic potential beyond the control of inflammation in RA.

Differential effects of glucose and lactate on glucosensing neurons in the ventromedial hypothalamic nucleus

Glucose directly alters the action potential frequency of glucosensing neurons in the ventromedial hypothalamic nucleus (VMN). Glucose-excited neurons increase, and glucose-inhibited neurons decrease, their action potential frequency as glucose increases from 0.1 to 2.5 mmol/l. Glucose-excited neurons utilize the ATP-sensitive K(+) channel (K(ATP) channel) to sense glucose, whereas glucose opens a chloride channel in glucose-inhibited neurons. We tested the hypothesis that lactate, an alternate energy substrate, also regulates the action potential frequency of VMN glucose-excited and -inhibited but not nonglucosensing neurons. As expected, lactate reversed the inhibitory effects of decreased glucose on VMN glucose-excited neurons via closure of the K(ATP) channel. Although increasing glucose from 2.5 to 5 mmol/l did not affect the activity of glucose-excited neurons, the addition of 0.5 mmol/l lactate or the K(ATP) channel blocker tolbutamide increased their action potential frequency. In contrast to the glucose-excited neurons, lactate did not reverse the effects of decreased glucose on VMN glucose-inhibited neurons. In fact, it increased their action potential frequency in both low and 2.5 mmol/l glucose. This effect was mediated by both K(ATP) and chloride channels. Nonglucosensing neurons were not affected by lactate. Thus, glucose and lactate have similar effects on VMN glucose-excited neurons, but they have opposing effects on VMN glucose-inhibited neurons.

The Na+/H+ exchange inhibitor: a new therapeutic approach for hepatic ischemia injury in rats

BACKGROUND

Na+/H+ exchanger (NHE) is one of the major mechanisms for restoring pH after ischemia-induced intracellular acidosis. However, activation of NHE during ischemia and reperfusion (I/R) is also involved in the paradoxical induction of cell injury. This study was designed to evaluate the effects of 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), an NHE inhibitor, on hepatic I/R injury.

METHODS

Partial hepatic ischemia was induced in male Wistar rats by cross-clamping the hepatic arterial and portal venous branches to the left lateral and median lobes of the liver for 120 minutes. The caudate and right lateral lobes were removed immediately after reperfusion. The concentrations of serum enzymes and ATP levels and energy charge in the live tissue were examined after 1-hour reperfusion.

RESULT

EIPA afforded considerable protection against I/R injury, as demonstrated by decreased transaminase release and reduced histologic hepatocyte damage and increased energy charge. The 7-day survival rate was significantly improved from 15.4% to 55.6% (P <.05).

CONCLUSIONS

This study shows for the first time that NHE may play an important role in the hepatic I/R injury and that EIPA should be considered as a new therapeutic approach to prevent hepatic I/R injury.

Tacrolimus inhibits discordant islet xenograft rejection: a study in the pig-to-rat model

The aim of the present study was to evaluate the immunosuppressive effect of tacrolimus (TAC) in discordant islet xenotransplantation. Fetal porcine islet-like cell clusters (ICCs) were transplanted under the kidney capsule in normoglycemic rats treated with TAC monotherapy, TAC plus other immunosuppressive drugs or cyclosporin A (CsA) monotherapy. Twelve or 24 days after transplantation, the extent of a cellular infiltration in the xenografts was evaluated using immunohistochemistry. In some animals, the grafts were examined for antibody and complement deposition and the levels of xenoreactive antibodies in serum were determined. In untreated rats, the xenografts were completely rejected after 12 days and no intact ICCs remained. TAC monotherapy (at 0.5 and 1.0 mg/kg b.w.) almost completely inhibited rejection for up to 12 days. In animals treated with TAC monotherapy (at 0.5 mg/kg b.w.), rejection was markedly inhibited for up to 24 days. However, the effect after 24 days was not consistent and in some grafts there were signs of rejection. The protective effect of TAC observed in this study is in contrast to the findings in rats given CsA monotherapy in which no or only a marginal effect on islet xenograft rejection was observed. Only when CsA was given at 20 mg/kg b.w., an inhibitory effect could be observed. Immunosuppression with TAC at a suboptimal dose (0.3 mg/kg b.w.) plus 15-deoxyspergualin or brequinar also had an inhibitory effect on the rejection. In animals given TAC plus mycophenolate mofetil, a protective effect was observed as well; however, this effect was not consistent.

Importance of the Gal alpha1-3 Gal antigen in discordant islet xenotransplantation: immunosuppression, which inhibits porcine islet xenograft rejection in ordinary mice, is equally effective in Gal-knockout mice

BACKGROUND

Islet xenotransplantation will most likely be performed in diabetic patients treated with immunosuppressive drugs. The importance of the galactosyl alpha(1-3) galactose (Galalpha1-3Gal) antigen in immunosuppressed islet xenograft recipients has not been studied.

METHODS

Fetal porcine islet-like cell clusters (ICCs) were transplanted into the renal subcapsular space of both Gal-knockout mice and ordinary mice. Transplantations were performed in untreated mice and mice immunosuppressed with cyclosporine A (CsA) plus 15-deoxyspergualin (DSG). Studies were also performed in immunosuppressed Gal-knockout mice that had been actively immunized against Galalpha1-3Gal. Evaluation was performed 12 days after transplantation using morphologic techniques. The levels of serum immunoglobulin (Ig)G and IgM to the Galalpha1-3Gal antigen or to the ICCs were determined.

RESULTS

No difference in the morphologic appearance could be seen between ordinary mice and Gal-knockout mice. No deposits of IgG, IgM, or C3 could be detected. Almost no difference could be seen between immunosuppressed Gal-knockout mice and immunosuppressed ordinary mice. In immunosuppressed, immunized Gal-knockout mice, the results were similar. In ordinary mice treated with CsA+DSG, the levels of anti-Gal IgM were lower than they were in untreated mice, whereas the levels of anti-Gal IgG were similar. In Gal-knockout mice (including immunized animals) treated with CsA+DSG, the levels of anti-Gal IgG and IgM were lower than they were in untreated Gal-knockout mice.

CONCLUSIONS

After renal subcapsular transplantation, antibodies against Galalpha1-3Gal have no major influence on islet xenograft rejection in the pig-to-mouse model. Immunosuppression, which inhibits rejection in the pig-to-mouse model, is equally effective when transplantation is performed across the Galalpha1-3Gal barrier.

Synthetic furanones inhibit quorum-sensing and enhance bacterial clearance in Pseudomonas aeruginosa lung infection in mice

INTRODUCTION

Antibiotics are used to treat bacterial infections by killing the bacteria or inhibiting their growth, but resistance to antibiotics can develop readily. The discovery that bacterial quorum-sensing regulates bacterial virulence as well as the formation of biofilms opens up new ways to control certain bacterial infections. Furanone compounds capable of inhibiting bacterial quorum-sensing systems have been isolated from the marine macro alga Delisea pulchra.

OBJECTIVES

Two synthetic furanones were tested for their ability to attenuate bacterial virulence in the mouse models of chronic lung infection by targeting bacterial quorum-sensing without directly killing bacteria or inhibiting their growth.

METHODS

Study I. Mice with Escherichia coli MT102 [luxR-PluxI-gfp(ASV)] lung infection were injected intravenously with N-acyl homoserine lactones with or without furanones to test the interference of furanones with quorum-sensing. Study II. Mice with lung infection by Pseudomonas aeruginosa PAO1 [dsred, lasR-PlasB-gfp(ASV)] were injected intravenously with furanones to evaluate their inhibiting effects on quorum-sensing. Study III. Mice with P. aeruginosa PAO1 lung infection were treated with different doses of furanones to evaluate the therapeutic effects of furanones on the lung infection.

RESULTS

Furanones successfully interfered with N-acyl homoserine lactone and suppressed bacterial quorum-sensing in lungs, which resulted in decreases in expression of green fluorescent protein. Furanones accelerated lung bacterial clearance, and reduced the severity of lung pathology. In a lethal P. aeruginosa lung infection, treatment with furanone significantly prolonged the survival time of the mice.

CONCLUSION

Synthetic furanone compounds inhibited bacterial quorum-sensing in P. aeruginosa and exhibited favourable therapeutic effects on P. aeruginosa lung infection.

IFNgamma deficient C57BL/6 (H-2b) mice develop collagen induced arthritis with predominant usage of T cell receptor Vbeta6 and Vbeta8 in arthritic joints

BACKGROUND

Transgenic deficiency in interferon gamma (IFNgamma) or IFNgamma receptor makes resistant strains of mice bearing H-2(b) or H-2(d) susceptible to collagen induced arthritis (CIA).

OBJECTIVE

To determine whether the escape from regulation of disease susceptibility at the major histocompatibility complex level involves a new use of autoimmune T cells expressing T cell receptor (TCR) Vbeta that vary from the cell populations previously identified within arthritic joints.

METHODS

Arthritis was induced by a standard protocol with type II bovine collagen (CII) in complete Freund's adjuvant. Clinical features, histopathology, immunological responses, and TCR profile in arthritic joints in IFNgamma knockout C57BL/6 (B6.IFNgamma KO) mice (H-2(b)) were compared directly with those in DBA/1 mice (H-2(q)).

RESULTS

60-80% of B6.IFNgamma KO mice developed a progressive arthritis with a similar clinical course to classical CIA in DBA/1 mice. The affected joints in B6.IFNgamma KO mice had an erosive form of arthritis with similar features to joint disease in DBA/1 mice. B6.IFNgamma KO mice produced significantly higher levels of IgG2b and IgG1 autoantibodies to murine CII and showed increased proliferative response to CII compared with B6 mice. Comparable levels of interleukin 1beta and tumour necrosis factor alpha expression were detected in arthritic joints from beta6.IFNgamma KO and DBA/1 mice. B6.IFNgammaKO mice used predominantly TCR Vbeta6 and Vbeta8 in arthritic joints. This TCR Vbeta profile is similar to that found in DBA/1 mice with CIA.

CONCLUSIONS

C57BL/6 mice deficient in IFNgamma production can develop arthritis that resembles classical CIA. These data suggest that IFNgamma is a key factor mediating susceptibility to CIA.

Selectivity in vibrationally mediated single-molecule chemistry

The selective excitation of molecular vibrations provides a means to directly influence the speed and outcome of chemical reactions. Such mode-selective chemistry has traditionally used laser pulses to prepare reactants in specific vibrational states to enhance reactivity or modify the distribution of product species. Inelastic tunnelling electrons may also excite molecular vibrations and have been used to that effect on adsorbed molecules, to cleave individual chemical bonds and induce molecular motion or dissociation. Here we demonstrate that inelastic tunnelling electrons can be tuned to induce selectively either the translation or desorption of individual ammonia molecules on a Cu(100) surface. We are able to select a particular reaction pathway by adjusting the electronic tunnelling current and energy during the reaction induction such that we activate either the stretching vibration of ammonia or the inversion of its pyramidal structure. Our results illustrate the ability of the scanning tunnelling microscope to probe single-molecule events in the limit of very low yield and very low power irradiation, which should allow the investigation of reaction pathways not readily amenable to study by more conventional approaches.