Methionine aminopeptidase (type 2) is the common target for angiogenesis inhibitors AGM-1470 and ovalicin

BACKGROUND

Angiogenesis, the formation of new blood vessels, is essential for tumor growth. The inhibition of angiogenesis is therefore emerging as a promising therapy for cancer. Two natural products, fumagillin and ovalicin, were discovered to be potent inhibitors of angiogenesis due to their inhibition of endothelial cell proliferation. An analog of fumagillin, AGM-1470, is currently undergoing clinical trials for the treatment of a variety of cancers. The underlying molecular mechanism of the inhibition of angiogenesis by these natural drugs has remained unknown.

RESULTS

Both AGM-1470 and ovalicin bind to a common bifunctional protein, identified by mass spectrometry as the type 2 methionine aminopeptidase (MetAP2). This protein also acts as an inhibitor of eukaryotic initiation factor 2alpha (elF-2alpha) phosphorylation. Both drugs potently inhibit the methionine aminopeptidase activity of MetAP2 without affecting its ability to block elF-2alpha phosphorylation. There are two types of methionine aminopeptidase found in eukaryotes, but only the type 2 enzyme is inhibited by the drugs. A series of analogs of fumagillin and ovalicin were synthesized and their potency for inhibition of endothelial cell proliferation and inhibition of methionine aminopeptidase activity was determined. A significant correlation was found between the two activities.

CONCLUSIONS

The protein MetAP2 is a common molecular target for both AGM-1470 and ovalicin. This finding suggests that MetAP2 may play a critical role in the proliferation of endothelial cells and may serve as a promising target for the development of new anti-angiogenic drugs.

Cancer therapy in the necroptosis era

Necroptosis is a caspase-independent form of regulated cell death executed by the receptor-interacting protein kinase 1 (RIP1), RIP3, and mixed lineage kinase domain-like protein (MLKL). Recently, necroptosis-based cancer therapy has been proposed to be a novel strategy for antitumor treatment. However, a big controversy exists on whether this type of therapy is feasible or just a conceptual model. Proponents believe that because necroptosis and apoptosis use distinct molecular pathways, triggering necroptosis could be an alternative way to eradicate apoptosis-resistant cancer cells. This hypothesis has been preliminarily validated by recent studies. However, some skeptics doubt this strategy because of the intrinsic or acquired defects of necroptotic machinery observed in many cancer cells. Moreover, two other concerns are whether or not necroptosis inducers are selective in killing cancer cells without disturbing the normal cells and whether it will lead to inflammatory diseases. In this review, we summarize current studies surrounding this controversy on necroptosis-based antitumor research and discuss the advantages, potential issues, and countermeasures of this novel therapy.

Molecular recognition of angiogenesis inhibitors fumagillin and ovalicin by methionine aminopeptidase 2

Angiogenesis inhibitors are a novel class of promising therapeutic agents for treating cancer and other human diseases. Fumagillin and ovalicin compose a class of structurally related natural products that potently inhibit angiogenesis by blocking endothelial cell proliferation. A synthetic analog of fumagillin, TNP-470, is currently undergoing clinical trials for treatment of a variety of cancers. A common target for fumagillin and ovalicin recently was identified as the type 2 methionine aminopeptidase (MetAP2). These natural products bind MetAP2 covalently, inhibiting its enzymatic activity. The specificity of this binding is underscored by the lack of inhibition of the closely related type 1 enzyme, MetAP1. The molecular basis of the high affinity and specificity of these inhibitors for MetAP2 has remained undiscovered. To determine the structural elements of these inhibitors and MetAP2 that are involved in this interaction, we synthesized fumagillin analogs in which each of the potentially reactive epoxide groups was removed either individually or in combination. We found that the ring epoxide in fumagillin is involved in the covalent modification of MetAP2, whereas the side chain epoxide group is dispensable. By using a fumagillin analog tagged with fluorescein, His-231 in MetAP2 was identified as the residue that is covalently modified by fumagillin. Site-directed mutagenesis of His-231 demonstrated its importance for the catalytic activity of MetAP2 and confirmed that the same residue is covalently modified by fumagillin. These results, in agreement with a recent structural study, suggest that fumagillin and ovalicin inhibit MetAP2 by irreversible blockage of the active site.

Central role of endogenous gamma interferon in protective immunity against blood-stage Plasmodium chabaudi AS infection

The role of endogenous gamma interferon (IFN-gamma) in protective immunity against blood-stage Plasmodium chabaudi AS malaria was studied using IFN-gamma gene knockout (GKO) and wild-type (WT) C57BL/6 mice. Following infection with 10(6) parasitized erythrocytes, GKO mice developed significantly higher parasitemia during acute infection than WT mice and had severe mortality. In infected GKO mice, production of interleukin 12 (IL-12) p70 and tumor necrosis factor alpha in vivo and IL-12 p70 in vitro by splenic macrophages was significantly reduced compared to that in WT mice and the enhanced nitric oxide (NO) production observed in infected WT mice was completely absent. WT and GKO mice had comparable numbers of total nucleated spleen cells and B220(+) and Mac-1(+) spleen cells both before and after infection. Infected WT mice, however, had significantly more F4/80(+), NK1.1(+), and F4/80(+)Ia(+) spleen cells than infected GKO mice; male WT had more CD3(+) cells than male GKO mice. In comparison with those from WT mice, splenocytes from infected GKO mice had significantly higher proliferation in vitro in response to parasite antigen or concanavalin A stimulation and produced significantly higher levels of IL-10 in response to parasite antigen. Infected WT mice produced more parasite-specific immunoglobulin M (IgM), IgG2a, and IgG3 and less IgG1 than GKO mice. Significant gender differences in both GKO and WT mice in peak parasitemia levels, mortality, phenotypes of spleen cells, and proliferation of and cytokine production by splenocytes in vitro were apparent during infection. These results thus provide unequivocal evidence for the central role of endogenous IFN-gamma in the development of protective immunity against blood-stage P. chabaudi AS.

Genomic structure, chromosomal localization and expression profile of a novel melanoma differentiation associated (mda-7) gene with cancer specific growth suppressing and apoptosis inducing properties

Abnormalities in cellular differentiation are frequent occurrences in human cancers. Treatment of human melanoma cells with recombinant fibroblast interferon (IFN-beta) and the protein kinase C activator mezerein (MEZ) results in an irreversible loss in growth potential, suppression of tumorigenic properties and induction of terminal cell differentiation. Subtraction hybridization identified melanoma differentiation associated gene-7 (mda-7), as a gene induced during these physiological changes in human melanoma cells. Ectopic expression of mda-7 by means of a replication defective adenovirus results in growth suppression and induction of apoptosis in a broad spectrum of additional cancers, including melanoma, glioblastoma multiforme, osteosarcoma and carcinomas of the breast, cervix, colon, lung, nasopharynx and prostate. In contrast, no apparent harmful effects occur when mda-7 is expressed in normal epithelial or fibroblast cells. Human clones of mda-7 were isolated and its organization resolved in terms of intron/exon structure and chromosomal localization. Hu-mda-7 encompasses seven exons and six introns and encodes a protein with a predicted size of 23.8 kDa, consisting of 206 amino acids. Hu-mda-7 mRNA is stably expressed in the thymus, spleen and peripheral blood leukocytes. De novo mda-7 mRNA expression is also detected in human melanocytes and expression is inducible in cells of melanocyte/melanoma lineage and in certain normal and cancer cell types following treatment with a combination of IFN-beta plus MEZ. Mda-7 expression is also induced during megakaryocyte differentiation induced in human hematopoietic cells by treatment with TPA (12-O-tetradecanoyl phorbol-13-acetate). In contrast, de novo expression of mda-7 is not detected nor is it inducible by IFN-beta+MEZ in a spectrum of additional normal and cancer cells. No correlation was observed between induction of mda-7 mRNA expression and growth suppression following treatment with IFN-beta+MEZ and induction of endogenous mda-7 mRNA by combination treatment did not result in significant intracellular MDA-7 protein. Radiation hybrid mapping assigned the mda-7 gene to human chromosome 1q, at 1q 32.2 to 1q41, an area containing a cluster of genes associated with the IL-10 family of cytokines. Mda-7 represents a differentiation, growth and apoptosis associated gene with potential utility for the gene-based therapy of diverse human cancers.

Neurocognitive effects of treatment interruption in stable HIV-positive patients in an observational cohort

OBJECTIVE

Prior studies have shown improved neurocognition with initiation of antiretroviral treatment (ART) in HIV. We hypothesized that stopping ART would be associated with poorer neurocognitive function.

METHODS

Neurocognitive function was assessed as part of ACTG 5170, a multicenter, prospective observational study of HIV-infected subjects who elected to discontinue ART. Eligible subjects had CD4 count >350 cells/mm(3), had HIV RNA viral load <55,000 cp/mL, and were on ART (>or=2 drugs) for >or=6 months. Subjects stopped ART at study entry and were followed for 96 weeks with a neurocognitive examination.

RESULTS

A total of 167 subjects enrolled with a median nadir CD4 of 436 cells/mm(3) and 4.5 median years on ART. Significant improvements in mean neuropsychological scores of 0.22, 0.39, 0.53, and 0.74 were found at weeks 24, 48, 72, and 96 (all p < 0.001). In the 46 subjects who restarted ART prior to week 96, no significant changes in neurocognitive function were observed.

CONCLUSION

Subjects with preserved immune function found that neurocognition improved significantly following antiretroviral treatment (ART) discontinuation. The balance between the neurocognitive cost of untreated HIV viremia and the possible toxicities of ART require consideration.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that discontinuing ART is associated with an improvement in 2 neuropsychological tests (Trail-Making Test A & B and the Wechsler Adult Intelligence Scale-Revised Digit Symbol subtest) for up to 96 weeks. Resuming ART was not associated with a decline in these scores for up to 45 weeks.

Baseline neutrophil-lymphocyte ratio (NLR) is associated with survival and response to treatment with second-line chemotherapy for advanced prostate cancer independent of baseline steroid use

BACKGROUND

The neutrophil-lymphocyte ratio (NLR), proposed as an indicator of cancer-related inflammation, has known prognostic value in prostate cancer. We examine its association with survival (OS) and response in patients treated with second-line chemotherapy.

METHODS

We analysed patients with metastatic castration-resistant prostate cancer (mCRPC) treated in the TROPIC trial, evaluating cabazitaxel versus mitoxantrone. Cox regression models were used to investigate the association of baseline NLR (BLNLR) with OS and the significance of a change in NLR count with treatment. Logistic regression models were used to determine the association of BLNLR counts with prostate specific antigen (PSA) and RECIST responses. The optimal NLR cut-off was established based on the concordance index of different values.

RESULTS

Data from 755, 654 and 405 patients was available for OS, PSA and RECIST response analysis respectively. Median OS was 14.0 months [95% confidence interval (CI) 13.2-14.8]. Median NLR was 2.9 (IQR: 1.9-5.1). BLNLR was associated with survival (HR 1.5, 95% CI 1.1-2.1, P = 0.011) in multivariable analysis (MVA) independently of variables included in the Halabi nomogram, treatment arm and corticosteroid use. The optimal cut-off for a dichotomous NLR was selected at 3.0 based on its higher c-index related to survival. BLNLR ≥3.0 was associated with lower PSA response (40.1% versus 59.9%; P < 0.001) and RECIST response (7.7% versus 15.6%, P = 0.022) in MVA. Conversion from high (≥3) to low (<3) NLR was associated with improved survival (HR 0.66; 95% CI 0.51-0.85; P = 0.001) and higher PSA response rates (66.4% versus 33.6%; P = 0.000). Use of corticosteroids at baseline did not modify the association between NLR and survival.

CONCLUSIONS

NLR is a valid prognostic biomarker in CRPC and is associated with survival, PSA and RECIST responses in patients treated with second-line chemotherapy. Changes in NLR counts with treatment may indicate benefit. NLR prognostic value is independent of prior use of corticosteroids.

CLINICALTRIALSGOV

NCT00417079.

Angiotensin-(1-7) inhibits angiotensin II-stimulated phosphorylation of MAP kinases in proximal tubular cells

Angiotensin-converting enzyme 2 (ACE2) is a homolog of ACE, which is not blocked by ACE inhibitors. High amounts of ACE2 are present in the proximal tubule, and ACE2 catalyzes generation of angiotensin 1-7 (Ang-(1-7)) by this segment. Ang-(1-7) binds to a receptor distinct from the AT1 or AT2 Ang II receptor, identified as the mas receptor. We studied the effects of Ang-(1-7) on Ang II-mediated cell signaling pathways in proximal tubule. In primary cultures of rat proximal tubular cells, activation of mitogen-activated protein kinases (MAPK) was detected by immunoblotting, in the presence or absence of agonists/antagonists. Transforming growth factor-beta1 (TGF-beta1) was measured by enzyme-linked immunosorbent assay. Ang II (5 min, 10(-7) M) stimulated phosphorylation of the three MAPK (p38, extracellular signal-related kinase (ERK 1/2), and c-Jun N-terminal kinase (JNK)). While incubation of proximal tubular cells with Ang-(1-7) alone did not significantly affect MAPK phosphorylation, Ang-(1-7) (10(-7) M) completely inhibited Ang II-stimulated phosphorylation of p38, ERK 1/2, and JNK. This inhibitory effect was reversed by the Ang-(1-7) receptor antagonist, D-Ala7-Ang-(1-7). Ang II significantly increased production of TGF-beta1 in proximal tubular cells, an effect that was partly inhibited by Ang-(1-7). Ang-(1-7) had no significant effect on cyclic 3',5'-adenosine monophosphate production in these cells. In summary, Ang-(1-7) inhibits Ang II-stimulated MAPK phosphorylation in proximal tubular cells. Generation of Ang-(1-7) by proximal tubular ACE2 could thereby serve a protective role by counteracting the effects of locally generated Ang II.

Effects of overexpression of the Na+-Ca2+ exchanger on [Ca2+]i transients in murine ventricular myocytes

We measured [Ca2+]i and [Na+]i in isolated transgenic (TG) mouse myocytes overexpressing the Na+-Ca2+ exchanger and in wild-type (WT) myocytes. In TG myocytes, the peak systolic level and amplitude of electrically stimulated (ES) [Ca2+]i transients (0.25 Hz) were not significantly different from those in WT myocytes, but the time to peak [Ca2+]i was significantly prolonged. The decline of ES [Ca2+]i transients was significantly accelerated in TG myocytes. The decline of a long-duration (4-s) caffeine-induced [Ca2+]i transient was markedly faster in TG myocytes, and [Na+]i was identical in TG and WT myocytes, indicating that the overexpressed Na+-Ca2+ exchanger is functionally active. The decline of a short-duration (100-ms) caffeine-induced [Ca2+]i transient in 0 Na+/0 Ca2+ solution did not differ between the two groups, suggesting that the sarcoplasmic reticulum (SR) Ca2+-ATPase function is not altered by overexpression of the Na+-Ca2+ exchanger. There was no difference in L-type Ca2+ current density in WT and TG myocytes. However, the sensitivity of ES [Ca2+]i transients to nifedipine was reduced in TG myocytes. This maintenance of [Ca2+]i transients in nifedipine was inhibited by Ni2+ and required SR Ca2+ content, consistent with enhanced Ca2+ influx by reverse Na+-Ca2+ exchange, and the resulting Ca2+-induced Ca2+ release from SR. The rate of rise of [Ca2+]i transients in nifedipine in TG myocytes was much slower than when both the L-type Ca2+ current and the Na+-Ca2+ exchange current function together. In TG myocytes, action potential amplitude and action potential duration at 50% repolarization were reduced, and action potential duration at 90% repolarization was increased, relative to WT myocytes. These data suggest that under these conditions, overexpression of the Na+-Ca2+ exchanger in TG myocytes accelerates the decline of [Ca2+]i during relaxation, indicating enhanced forward Na+-Ca2+ exchanger function. Increased Ca2+ influx also appears to occur, consistent with enhanced reverse function. These findings provide support for the physiological importance of both these modes of Na+-Ca2+ exchange.

Urea gradient size-exclusion chromatography enhanced the yield of lysozyme refolding

Protein refolding is still a bottleneck for large-scale production of valuable proteins expressed as inclusion bodies in Escherichia coli. Usually biologically active proteins cannot be obtained with high yield at a high concentration after refolding. In order to meet the challenge of protein refolding a urea gradient gel filtration-refolding system was developed in this article. A Superdex 75 column was pre-equilibrated with a linear decreased urea gradient, the denatured protein experienced the gradual decrease in urea concentration as it went through the column. The refolding of denatured lysozyme showed this method could significantly increase the activity recovery of denatured lysozyme at high protein concentration. The activity recovery of 90% was obtained from the initial protein concentration up to 17 mg/ml within 40 min.

MicroRNA-324-3p regulates nasopharyngeal carcinoma radioresistance by directly targeting WNT2B

PURPOSE

Radioresistance severely restricts the clinical treatment of nasopharyngeal carcinoma (NPC). Accumulating evidence demonstrates that aberrant expression of microRNAs (miRNAs) contributes to cancer progression and sensitivity to radiation. Therefore, we aimed to identify miRNAs associated with radioresistance in NPC.

METHODS

Aberrant miRNA-324-3p expression in NPC CNE-2 cells with radioresistance (CNE-2-Rs), compared to its parental cells, was screened by high-throughput sequencing technology and determined by quantitative reverse transcription-polymerase chain reaction analysis (qRT-PCR) analysis. Bioinformatic analysis was used to predict the downstream target genes of miRNA-324-3p. Then, functional and mechanical analyses of miRNA-324-3p in NPC radioresistance were performed by overexpression and down-regulation of miRNA-324-3p in CNE-2-Rs cells and its parental cells. Finally, the clinical significance of miRNA-324-3p and WNT2B was investigated in NPC tissues.

RESULTS

Our data reveal that the expression of miRNA-324-3p is significantly decreased in CNE-2-Rs cells compared to its parental cells, and WNT2B is predicted to be the downstream target of miRNA-324-3p. Both overexpression and down-regulation of miRNA-324-3p following irradiation result in radiosensitivity alterations and protein changes of WNT2B signalling pathway in CNE-2-Rs cells and its parental cells. Importantly, down-regulation of miRNA-324-3p and up-regulation of WNT2B are significantly correlated with advanced clinical stages of NPC and this inverse expression pattern is also observed in NPC tissues before and after irradiation.

CONCLUSIONS

The present study reveals that miRNA-324-3p contributes to the radioresistance of NPC by regulating the WNT2B signalling pathway. Both miRNA-324-3p and WNT2B are potential biomarkers for radioresistance in NPC, which may serve as valuable targets for reversing radioresistance in the management of NPC.

Calcium influx factor is synthesized by yeast and mammalian cells depleted of organellar calcium stores

Depletion of endoplasmic reticulum Ca2+ stores leads to the entry of extracellular Ca2+ into the cytoplasm, a process termed capacitative or store-operated Ca2+ entry. Partially purified extracts were prepared from the human Jurkat T lymphocyte cell line and yeast in which Ca2+ stores were depleted by chemical and genetic means, respectively. After microinjection into Xenopus laevis oocytes, the extracts elicited a wave of increased cytoplasmic free Ca2+ ([Ca2+]i) that spread from the point of injection across the oocyte. Extracts from cells with replete organellar Ca2+ stores were inactive. The increases depended on extracellular Ca2+, were unaffected by the inositol 1,4,5-trisphosphate (IP3) inhibitor heparin or an anti-IP3 receptor antibody and were unchanged when the endoplasmic reticulum was segregated to the hemisphere opposite the injection site by centrifugation. Confocal microscopy revealed that [Ca2+]i increases were most pronounced at the periphery of the oocyte. The patterns of [Ca2+]i increases were replicated by computer simulations based on a diffusible messenger of about 700 Da that directly activates Ca2+ influx. In addition, ICRAC, a Ca2+ release-activated Ca2+ current monitored in Jurkat cells by whole-cell patch clamp recordings, was more rapidly activated when active extracts were included in the patch pipette than by the inclusion of a Ca2+ chelator or IP3. These data support the existence in yeast and mammalian cells depleted of Ca2+ stores of a functionally conserved diffusible calcium influx factor that directly activates Ca2+ influx.

Suppressed T helper 2 immunity and prolonged survival of a nematode parasite in protein-malnourished mice

Protein malnutrition may increase susceptibility to gastrointestinal parasitic infections, possibly as a result of impaired intestinal and/or systemic T helper 2 (Th2) effector responses induced by down-regulation of Th2 cytokines and/or up-regulation of Th1 cytokines. To test this hypothesis, female BALB/c mice (n = 18/diet) were fed a control (24%), marginal (7%), or deficient (3%) protein diet and given a challenge infection with Heligmosomoides polygyrus. The 3% mice had higher worm burdens at 1, 2, and 4 weeks postchallenge infection (pci), lower increases in serum IgE, reduced intestinal eosinophilia, and depressed mucosal mast cell proliferation and activation at 1-2 weeks pci. To determine whether these suppressed effector responses resulted from altered spleen and mesenteric lymph node (MLN) cytokine production, cells were restimulated in vitro with parasite antigen and cytokine concentrations were measured. Deficient MLN cells secreted significantly less IL-4 and more IFN-gamma at 1-2 weeks pci than did control MLN cells. Deficient spleen cells also secreted more IFN-gamma at 2 weeks pci compared with control spleen cells. From reverse transcription-PCR analyses, the 3% mice also had lower IL-4 mRNA level in spleen and MLN at 1-2 weeks pci. Our study supports the hypothesis that protein malnutrition increases the survival of a nematode parasite by decreasing gut-associated IL-4 (Th2) and increasing IFN-gamma (Th1) within 2 weeks pci, leading to reduced intestinal and systemic Th2 effector responses.

Modulation of miR-34a/SIRT1 signaling protects cochlear hair cells against oxidative stress and delays age-related hearing loss through coordinated regulation of mitophagy and mitochondrial biogenesis

Mitophagy and mitochondrial biogenesis are 2 pathways that regulate mitochondrial content and metabolism maintaining cellular homeostasis. The imbalance between these opposing processes impairs mitochondrial function and is suggested to be the pathophysiological basis of a variety of neurodegenerative diseases and aging. Here we investigated the role of mitophagy and mitochondrial biogenesis in oxidative damage to the cochlear hair cells and age-related hearing loss. In cultured mouse House Ear Institute-Organ of Corti 1 hair cells, oxidative stress activated mitophagy but inhibited mitochondrial biogenesis and impaired mitochondrial function. Pharmacological inhibition of miR-34a/SIRT1 signaling enhanced mitophagy, mitochondrial biogenesis, and attenuated House Ear Institute-Organ of Corti 1 cell death induced by oxidative stress. In the cochlea of C57BL/6 mice, mitophagy and mitochondrial biogenesis were both upregulated during aging. Long-term supplementation with resveratrol, a SIRT1 activator, not only improved the balance between mitophagy and mitochondrial biogenesis but also significantly reduced age-related cochlear hair cell loss, spiral ganglion neuron loss, stria vascularis atrophy, and hearing threshold shifts in C57BL/6 mice. Moreover, SIRT1 overexpression or miR-34a deficiency both attenuated age-related cochlear hair cell loss and hearing loss in C57BL/6 mice. Our findings reveal that imbalance between mitophagy and mitochondrial biogenesis contributes to cochlea hair cell damage caused by oxidative stress and during aging. Coordinated regulation of these 2 processes by miR-34a/SIRT1 signaling might serve as a promising approach for the treatment of age-related cochlear degeneration and hearing loss.

Two-kidney, two clip renovascular hypertensive rats can be used as stroke-prone rats

BACKGROUND AND PURPOSE

The cerebrovascular lesions in stroke-prone spontaneously hypertensive rats are not only dependent on high blood pressure but partly related to pressure-independent genetic factors. The aim of the present study was to observe whether spontaneous stroke occurred in renovascular hypertensive rats without a genetic deficiency.

METHODS

The 1-kidney, 1 clip (1k1c); 2-kidney, 1 clip (2k1c); and 2-kidney, 2 clip (2k2c) methods were used to induce hypertension in male Sprague-Dawley rats with a ring-shaped silver clip. Sham-operated rats were used as controls. Blood pressure and neurological symptoms were observed in the rats without any artificial inducement. Brain sections stained with hematoxylin-eosin and phosphotungstic acid-hematoxylin were examined under a microscope to determine stroke foci.

RESULTS

The attack rate of stable hypertension was 100% (55/55) in the 2k2c group, which was significantly higher than that in the 1k1c (23/30, 76.7%) and 2k1c (21/30, 70%) groups (P<0.01). None of the rats in the 2k2c group died of acute renal failure or suffered from diffuse cerebral lesions postoperatively. Forty weeks after renal artery constriction, the incidence of spontaneous stroke in the 2k2c group was 61.8% (34/55), which was significant higher than that in the 1k1c (7/30, 23.3%) and 2k1c (5/30,16.7%) groups (P<0.01). Stroke foci were not observed in normotensive controls.

CONCLUSIONS

We conclude that 2k2c renovascular hypertensive rats with proper renal artery constriction can be used as stroke-prone renovascular hypertensive rats independent of a genetic deficiency.

Effect of dietary xylooligosaccharides on intestinal characteristics, gut microbiota, cecal short-chain fatty acids, and plasma immune parameters of laying hens

This study examined the prebiotic effects of xylooligosaccharides (XOS) on intestinal characteristics, gut microbiota, cecal short-chain fatty acids, plasma calcium metabolism, and immune parameters of laying hens. A total of 1,080 White Lohmann laying hens (28 wk of age) was assigned to 6 dietary treatments that included XOS at concentrations of 0, 0.01, 0.02, 0.03, 0.04, or 0.05% for 8 weeks. Each treatment had 6 replicates with 10 cages (3 birds/cage). Blood, intestinal tissues, and cecal digesta samples were collected from chickens at the end of the experiment. Villus height, crypt depth, the villus to crypt (VH: CD) ratio, and the relative length of different intestinal sections were evaluated. Additionally, the number of microorganisms and the content of short-chain fatty acids in cecal digesta samples were determined. Plasma concentrations of immunoglobulin A (IgA), immunoglobulin G, immunoglobulin M (IgM), interleukin 2 (IL-2), tumor necrosis factor-α(TNF-α), 1, 25-dihydroxyvitamin D3 (1,25(OH)2D3), calcitonin (CT), and parathyroid hormone (PTH) were also determined. The results showed that villus height and the VH: CD ratio of the jejunum were increased (linear, P < 0.01) with the increase in dietary XOS concentration, and the relative length of the jejunum (P = 0.03) was increased significantly in XOS diets. Dietary supplementation of XOS significantly increased (linear, P < 0.01) the number of Bifidobacteria in the cecum; however, total bacteria count, Lactobacillus, and Escherichia coli in the cecum were not affected by XOS supplementation. In addition, inclusion of XOS increased (linear, P < 0.01) the content of butyrate in the cecum; and the content of acetic acid showed a linear increasing trend (P = 0.053) with increasing concentration of XOS in the diets. Supplementation with XOS increased (quadratic, P < 0.05) the content of 1,25(OH)2D3 in plasma. There were no significant differences (P > 0.05) in the content of CT and PTH among dietary treatments. Furthermore, dietary XOS increased contents of IgA (linear, P < 0.05), TNF-α (linear, P < 0.05), IgM (linear, P < 0.05; quadratic, P < 0.05), and IL-2 (quadratic, P < 0.05). Taken together, it was suggested that supplemental XOS can enhance the intestinal health and immune function of laying hens by positively influencing the intestinal characteristics, gut microbiota, cecal short-chain fatty acids, and immune parameters.

Activation of connexin-43 hemichannels can elevate [Ca(2+)]i and [Na(+)]i in rabbit ventricular myocytes during metabolic inhibition

ATP depletion due to ischemia or metabolic inhibition (MI) causes Na(+) and Ca(2+) accumulation in myocytes, which may be in part due to opening of connexin-43 hemichannels. Halothane (H) has been shown to reduce conductance of connexin-43 hemichannels and to protect the heart against ischemic injury. We therefore investigated the effect of halothane on [Ca(2+)]i and [Na(+)]i in myocytes during MI. Isolated rabbit left ventricular myocytes were loaded with 4 microM fluo-3 AM for 30 min, or with 5 microM sodium green AM for 60 min at 37 degrees C. After washing, the myocytes were exposed to: (1) Normal HEPES solution; (2) MI solution (2 mM NaCN, 20 mM 2-deoxy-D-glucose and 0-glucose); or (3) MI+H (0.95 mM, 4.7 mM) for 60 min. Propidium iodide (PI, 25 microM) was added to all samples before data acquisition. The fluorescence intensity was measured by flow cytometry with 488 nm excitation and 530 nm emission for fluo-3 or sodium green, and 670 nm for PI. The [Ca(2+)]i and [Na(+)]i were then calculated by calibration. In some experiments, the effect of 10 microM tetrodotoxin (TTX) and 20 microM nifedipine (NIF) were studied. Metabolic inhibition for 60 min caused a significant increase in [Ca(2+)]i and [Na(+)]i in myocytes when compared to controls, which was significantly reduced by halothane in a dose-dependent fashion. In the presence of TTX and NIF, halothane also significantly reduced the rise in the [Ca(2+)]i and [Na(+)]i in myocytes subjected to MI. 1-heptanol, another gap junction blocker, had similar effects. Thus, halothane reduced [Ca(2+)]i and [Na(+)]i overload produced by MI in myocytes. This effect is not solely due to block of voltage-gated Na(+) and Ca(2+) channels, and is likely mediated by inhibiting the opening of connexin-43 hemichannels.

On the mapping of electrostatic properties from the multipole description of the charge density

A method is presented to calculate the electrostatic potential, the electric field and the electric-field gradient in a crystal from the atomic multipole expansion of the experimental charge density, as described by the Hansen-Coppens formalism [Hansen & Coppens (1978), Acta Cryst. A34, 909-921]. The electrostatic properties are expressed in terms of the positions and the charge-density parameters of the individual atoms. Contributions due to the procrystal charge density and the deformation charge density are compared. The method is illustrated by the calculation of the electrostatic potential maps of fully deuterated benzene and of iron(II) tetraphenylporphyrin.