RSC, an essential, abundant chromatin-remodeling complex

A novel 15-subunit complex with the capacity to remodel the structure of chromatin, termed RSC, has been isolated from S. cerevisiae on the basis of homology to the SWI/SNF complex. At least three RSC subunits are related to SWI/SNF polypeptides: Sth1p, Rsc6p, and Rsc8p are significantly similar to Swi2/Snf2p, Swp73p, and Swi3p, respectively, and were identified by mass spectrometric and sequence analysis of peptide fragments. Like SWI/SNF, RSC exhibits a DNA-dependent ATPase activity stimulated by both free and nucleosomal DNA and a capacity to perturb nucleosome structure. RSC is, however, at least 10-fold more abundant than SWI/SNF complex and is essential for mitotic growth. Contrary to a report for SWII/SNF complex, no association of RSC (nor of SWI/SNF complex) with RNA polymerase II holoenzyme was detected.

Ruxolitinib in corticosteroid-refractory graft-versus-host disease after allogeneic stem cell transplantation: a multicenter survey

Despite major improvements in allogeneic hematopoietic cell transplantation over the past decades, corticosteroid-refractory (SR) acute (a) and chronic (c) graft-versus-host disease (GVHD) cause high mortality. Preclinical evidence indicates the potent anti-inflammatory properties of the JAK1/2 inhibitor ruxolitinib. In this retrospective survey, 19 stem cell transplant centers in Europe and the United States reported outcome data from 95 patients who had received ruxolitinib as salvage therapy for SR-GVHD. Patients were classified as having SR-aGVHD (n=54, all grades III or IV) or SR-cGVHD (n=41, all moderate or severe). The median number of previous GVHD-therapies was 3 for both SR-aGVHD (1-7) and SR-cGVHD (1-10). The overall response rate was 81.5% (44/54) in SR-aGVHD including 25 complete responses (46.3%), while for SR-cGVHD the ORR was 85.4% (35/41). Of those patients responding to ruxolitinib, the rate of GVHD-relapse was 6.8% (3/44) and 5.7% (2/35) for SR-aGVHD and SR-cGVHD, respectively. The 6-month-survival was 79% (67.3-90.7%, 95% confidence interval (CI)) and 97.4% (92.3-100%, 95% CI) for SR-aGVHD and SR-cGVHD, respectively. Cytopenia and cytomegalovirus-reactivation were observed during ruxolitinib treatment in both SR-aGVHD (30/54, 55.6% and 18/54, 33.3%) and SR-cGVHD (7/41, 17.1% and 6/41, 14.6%) patients. Ruxolitinib may constitute a promising new treatment option for SR-aGVHD and SR-cGVHD that should be validated in a prospective trial.

Nuclear magnetic resonance spectroscopy on a (5-nanometer)3 sample volume

Application of nuclear magnetic resonance (NMR) spectroscopy to nanoscale samples has remained an elusive goal, achieved only with great experimental effort at subkelvin temperatures. We demonstrated detection of NMR signals from a (5-nanometer)(3) voxel of various fluid and solid organic samples under ambient conditions. We used an atomic-size magnetic field sensor, a single nitrogen-vacancy defect center, embedded ~7 nanometers under the surface of a bulk diamond to record NMR spectra of various samples placed on the diamond surface. Its detection volume consisted of only 10(4) nuclear spins with a net magnetization of only 10(2) statistically polarized spins.

Molybdenum disulfide (MoS₂) as a broadband saturable absorber for ultra-fast photonics

The nonlinear optical property of few-layered MoS₂ nanoplatelets synthesized by the hydrothermal exfoliation method was investigated from the visible to the near-infrared band using lasers. Both open-aperture Z-scan and balanced-detector measurement techniques were used to demonstrate the broadband saturable absorption property of few-layered MoS₂. To explore its potential applications in ultrafast photonics, we fabricated a passive mode locker for ytterbium-doped fibre laser by depositing few-layered MoS₂ onto the end facet of optical fiber by means of an optical trapping approach. Our laser experiment shows that few-layer MoS₂-based mode locker allows for the generation of stable mode-locked laser pulse, centered at 1054.3 nm, with a 3-dB spectral bandwidth of 2.7 nm and a pulse duration of 800 ps. Our finding suggests that few-layered MoS₂ nanoplatelets can be useful nonlinear optical material for laser photonics devices, such as passive laser mode locker, Q-switcher, optical limiter, optical switcher and so on.

Hormone-neurotransmitter interactions in the control of sexual behavior

The stimuli from a receptive female and/or copulation itself leads to the release of dopamine (DA) in at least three integrative hubs. The nigrostriatal system promotes somatomotor activity; the mesolimbic system subserves numerous types of motivation; and the medial preoptic area (MPOA) focuses the motivation onto specifically sexual targets, increases copulatory rate and efficiency, and coordinates genital reflexes. The previous (but not necessarily concurrent) presence of testosterone is permissive for DA release in the MPOA, both during basal conditions and in response to a female. One means by which testosterone may increase DA release is by upregulating nitric oxide synthase, which produces nitric oxide, which in turn increases DA release. Hormonal priming in females may also increase DA release in the MPOA, and copulatory activity may further increase DA levels in females. One of the intracellular effects of stimulation of DA D1 receptors in the MPOA of male rats may be increased expression of the immediate-early gene c-fos, which may mediate longer term responses to copulation. Furthermore, increased sexual experience led to increased immunoreactivity to Fos, the protein product of c-fos, following copulation to one ejaculation. Another intracellular mediator of DA's effects, particularly in castrates, may be the phosphorylation of steroid receptors. Finally, while DA is facilitative to copulation, 5-HT is generally inhibitory. 5-HT is released in the LHA, but not in the MPOA, at the time of ejaculation. Increasing 5-HT in the LHA by microinjection of a selective serotonin reuptake inhibitor (SSRI) increased the latency to begin copulating and also the latency to the first ejaculation, measured from the time the male first intromitted. These data may at least partially explain the decrease in libido and the anorgasmia of people taking SSRI antidepressants. One means by which LHA 5-HT decreases sexual motivation (i.e. increases the latency to begin copulating) may be by decreasing DA release in the NAcc, a major terminal of the mesolimbic system. Thus, reciprocal changes in DA and 5-HT release in different areas of the brain may promote copulation and sexual satiety, respectively.

Pharmacological ascorbate with gemcitabine for the control of metastatic and node-positive pancreatic cancer (PACMAN): results from a phase I clinical trial

BACKGROUND

Treatment for pancreatic cancer with pharmacological ascorbate (ascorbic acid, vitamin C) decreases tumor progression in preclinical models. A phase I clinical trial was performed to establish safety and tolerability of pharmacological ascorbate combined with gemcitabine in patients with biopsy-proven stage IV pancreatic adenocarcinoma.

DESIGN

Nine subjects received twice-weekly intravenous ascorbate (15-125 g) employing Simon's accelerated titration design to achieve a targeted post-infusion plasma level of ≥350 mg/dL (≥20 mM). Subjects received concurrent gemcitabine. Disease burden, weight, performance status, hematologic and metabolic laboratories, time to progression and overall survival were monitored.

RESULTS

Mean plasma ascorbate trough levels were significantly higher than baseline (1.46 ± 0.02 vs. 0.78 ± 0.09 mg/dL, i.e., 83 vs. 44 μM, p < 0.001). Adverse events attributable to the drug combination were rare and included diarrhea (n = 4) and dry mouth (n = 6). Dose-limiting criteria were not met for this study. Mean survival of subjects completing at least two cycles (8 weeks) of therapy was 13 ± 2 months.

CONCLUSIONS

Data suggest pharmacologic ascorbate administered concurrently with gemcitabine is well tolerated. Initial data from this small sampling suggest some efficacy. Further studies powered to determine efficacy should be conducted.

The vaginal microbiota, human papillomavirus and cervical dysplasia: a systematic review and network meta-analysis

BACKGROUND

Persistent infection with high-risk human papillomavirus can lead to cervical dysplasia and cancer. Recent studies have suggested associations between the composition of the vaginal microbiota, infection with human papillomavirus (HPV) and progression to cervical dysplasia and cancer.

OBJECTIVE

To assess how specific cervico-vaginal microbiota compositions are associated with HPV infection, cervical dysplasia and cancer, we conducted a systematic review and network meta-analysis (registered in PROSPERO: CRD42018112862).

SEARCH STRATEGY

PubMed, Web of science, Embase and Cochrane database.

SELECTION CRITERIA

All original studies describing at least two community state types of bacteria (CST), based on molecular techniques enabling identification of bacteria, and reporting the association with HPV infection, cervical dysplasia and/or cervical cancer.

DATA COLLECTION AND ANALYSIS

For the meta-analysis, a network map was constructed to provide an overview of the network relationships and to assess how many studies provided direct evidence for the different vaginal microbiota compositions and HPV, cervical dysplasia or cancer. Thereafter, the consistency of the model was assessed, and forest plots were constructed to pool and summarise the available evidence, presenting odds ratios and 95% confidence intervals.

MAIN RESULTS

Vaginal microbiota dominated by non-Lactobacilli species or Lactobacillus iners were associated with three to five times higher odds of any prevalent HPV and two to three times higher for high-risk HPV and dysplasia/cervical cancer compared with Lactobacillus crispatus.

CONCLUSIONS

These findings suggest an association between certain bacterial community types of the vaginal microbiota and HPV infection and HPV-related disease. This may be useful for guiding treatment options or serve as biomarkers for HPV-related disease.

TWEETABLE ABSTRACT

This network meta-analysis suggests an association between different vaginal bacterial community types and the risk of HPV.

A five-microRNA panel in plasma was identified as potential biomarker for early detection of gastric cancer

BACKGROUND

Circulating microRNAs (miRNAs) have been implicated as novel biomarkers for gastric cancer (GC) diagnosis. However, the mixture of GC subtypes may have led to the inconsistent circulating miRNA profiles, and the clinical performance of circulating miRNAs has not yet been evaluated independently on early detection of GC.

METHODS

A four-phase study was designed with a total of 160 cancer-free controls, 124 patients with gastric non-cardia adenocarcinoma (GNCA) and 36 patients diagnosed gastric cardia adenocarcinoma (GCA). In the discovery phase, we screened the miRNA expression profile in plasma of 40 GNCA patients (stage I) and 40 matched controls by TaqMan low density array (TLDA) chips with pooled samples. Differentially expressed miRNAs were further validated in individual sample using quantitative reverse-transcriptase PCR (qRT-PCR) in the training phase. Subsequently, in an independent validation phase, the identified miRNAs were evaluated in 48 GNCA patients (stage I) and 102 matched controls. Finally, the identified miRNAs were further assessed in an external validation phase including advanced GNCA and GCA patients. Additionally, the expression levels of identified miRNAs were measured in the media of BGC823 and MGC803 cell lines.

RESULTS

Five miRNAs (miR-16, miR-25, miR-92a, miR-451 and miR-486-5p) showed consistently elevated levels in plasma of the GC patients as compared with controls, and were identified to be potential markers for GNCA with area under the receiver operating characteristic (ROC) curves (AUCs) ranging from 0.850 to 0.925 and 0.694 to 0.790 in the training and validation phases, respectively. The five-miRNA panel presented a high diagnostic accuracy for the early-stage GNCA (AUCs=0.989 and 0.812 for the training and validation phases, respectively). Three miRNAs (miR-16, miR-25 and miR-92a) were excreted into the culture media of GC cell lines.

CONCLUSIONS

The five-miRNA panel in plasma may serve as a potential non-invasive biomarker in detecting the early-stage GC.

Frequency-dependent regulation of rat hippocampal somato-dendritic excitability by the K+ channel subunit Kv2.1

The voltage-dependent potassium channel subunit Kv2.1 is widely expressed throughout the mammalian CNS and is clustered primarily on the somata and proximal dendrites, but not axons, of both principal neurones and inhibitory interneurones of the cortex and hippocampus. This expression pattern suggests that Kv2.1-containing channels may play a role in the regulation of pyramidal neurone excitability. To test this hypothesis and to determine the functional role of Kv2. 1-containing channels, cultured hippocampal slices were incubated with antisense oligonucleotides directed against Kv2.1 mRNA. Western blot analysis demonstrated that Kv2.1 protein content of cultured slices decreased > 90 % following 2 weeks of treatment with antisense oligonucleotides, when compared with either control missense-treated or untreated cultures. Similarly, Kv2.1 immunostaining was selectively decreased in antisense-treated cultures. Sustained outward potassium currents, recorded in both whole-cell and outside-out patch configurations, demonstrated a selective reduction of amplitude only in antisense-treated CA1 pyramidal neurones. Under current-clamp conditions, action potential durations were identical in antisense-treated, control missense-treated and untreated slices when initiated by low frequency stimulation (0.2 Hz). In contrast, spike repolarization was progressively prolonged during higher frequencies of stimulation (1 Hz) only in cells from antisense-treated slices. Similarly, action potentials recorded during electrographic interictal activity in the 'high [K+]o' model of epilepsy demonstrated pronounced broadening of their late phase only in cells from antisense-treated slices. Consistent with the frequency-dependent spike broadening, calcium imaging experiments from single CA1 pyramidal neurones revealed that high frequency Schaffer collateral stimulation resulted in a prolonged elevation of dendritic [Ca2+]i transients only in antisense-treated neurones. These studies demonstrate that channels containing Kv2.1 play a role in regulating pyramidal neurone somato-dendritic excitability primarily during episodes of high frequency synaptic transmission.

Deficiency of the cysteine protease cathepsin S impairs microvessel growth

During angiogenesis, microvascular endothelial cells (ECs) secrete proteinases that permit penetration of the vascular basement membrane as well as the interstitial extracellular matrix. This study tested the hypothesis that cathepsin S (Cat S) contributes to angiogenesis. Treatment of cultured ECs with inflammatory cytokines or angiogenic factors stimulated the expression of Cat S, whereas inhibition of Cat S activity reduced microtubule formation by impairing cell invasion. ECs from Cat S-deficient mice showed reduced collagenolytic activity and impaired invasion of collagens type I and IV. Cat S-deficient mice displayed defective microvessel development during wound repair. This abnormal angiogenesis occurred despite normal vascular endothelial growth factor and basic fibroblast growth factor levels, implying an essential role for extracellular matrix degradation by Cat S during microvessel formation. These results demonstrate a novel function of endothelium-derived Cat S in angiogenesis.

GDNF acutely modulates excitability and A-type K(+) channels in midbrain dopaminergic neurons

Glial cell line-derived neurotrophic factor (GDNF) prevents lesion-induced death of midbrain dopaminergic neurons, but its function in normal brain remains uncertain. Here we show that GDNF acutely and reversibly potentiated the excitability of cultured midbrain neurons by inhibiting transient A-type K(+) channels. The effects of GDNF were limited to large, tyrosine hydroxylase (TH)-positive dopaminergic neurons, and were mediated by mitogen associated protein (MAP) kinase. Application of GDNF also elicited a MAP kinase-dependent enhancement of the excitability in dopaminergic neurons in midbrain slice. These results demonstrate an acute regulation of GDNF on ion channels and its underlying signaling mechanism, and reveal an unexpected role of GDNF in normal midbrain dopaminergic neurons.

Identification and characterization of a melanin-concentrating hormone receptor

Melanin-concentrating hormone (MCH), a neuropeptide expressed in central and peripheral nervous systems, plays an important role in the control of feeding behaviors and energy metabolism. An orphan G protein-coupled receptor (SLC-1/GPR24) has recently been identified as a receptor for MCH (MCHR1). We report here the identification and characterization of a G protein-coupled receptor as the MCH receptor subtype 2 (MCHR2). MCHR2 has higher protein sequence homology to MCHR1 than any other G protein-coupled receptor. The expression of MCHR2 has been detected in many regions of the brain. In contrast to MCHR1, which is intronless in the coding region and is located at the chromosomal locus 22q13.3, the MCHR2 gene has multiple exons and is mapped to locus 6q21. MCHR2 is specifically activated by nanomolar concentrations of MCH, binds to MCH with high affinity, and signals through Gq protein. This discovery is important for a full understanding of MCH biology and the development of potential therapeutics for diseases involving MCH, including obesity.

Protein synthesis-dependent and -independent regulation of hippocampal synapses by brain-derived neurotrophic factor

A fundamental difference between short-term and long-term forms of synaptic plasticity is the dependence on transcription and translation of new genes. Using organotypic cultures of hippocampal slices, we have investigated whether the modulation of synapses by brain-derived neurotrophic factor (BDNF) also requires protein synthesis. Long-term treatment of hippocampal slice cultures with BDNF increased the number of docked vesicles, but not that of reserve pool vesicles, at CA1 excitatory synapses. BDNF also increased the levels of the vesicle proteins synaptophysin, synaptobrevin, and synaptotagmin, without affecting the presynaptic membrane proteins syntaxin and SNAP-25, or the vesicle-binding protein synapsin-I. The increase in synaptophysin and synaptobrevin expression was moderate (2-fold) and occurred within 6 h after BDNF application. In contrast, synaptotagmin expression took 24 h to reach maximum levels (5-fold). The delayed increase in synaptotagmin was blocked by protein synthesis inhibitors, while the early increase in synaptophysin and synaptobrevin was not. Moreover, the BDNF-induced increase of synaptotagmin was blocked by inhibiting the cAMP/protein kinase A (PKA) pathway. However, BDNF did not activate PKA, and application of a PKA activator did not mimic the BDNF effect. Taken together, these results suggest a novel, protein synthesis-dependent form of BDNF modulation that requires cAMP gating.

Activity- and Ca(2+)-dependent modulation of surface expression of brain-derived neurotrophic factor receptors in hippocampal neurons

Brain-derived neurotrophic factor (BDNF) has been shown to regulate neuronal survival and synaptic plasticity in the central nervous system (CNS) in an activity-dependent manner, but the underlying mechanisms remain unclear. Here we report that the number of BDNF receptor TrkB on the surface of hippocampal neurons can be enhanced by high frequency neuronal activity and synaptic transmission, and this effect is mediated by Ca(2+) influx. Using membrane protein biotinylation as well as receptor binding assays, we show that field electric stimulation increased the number of TrkB on the surface of cultured hippocampal neurons. Immunofluorescence staining suggests that the electric stimulation facilitated the movement of TrkB from intracellular pool to the cell surface, particularly on neuronal processes. The number of surface TrkB was regulated only by high frequency tetanic stimulation, but not by low frequency stimulation. The activity dependent modulation appears to require Ca(2+) influx, since treatment of the neurons with blockers of voltage-gated Ca(2+) channels or NMDA receptors, or removal of extracellular Ca(2+), severely attenuated the effect of electric stimulation. Moreover, inhibition of Ca(2+)/calmodulin-dependent kinase II (CaMKII) significantly reduced the effectiveness of the tetanic stimulation. These findings may help us to understand the role of neuronal activity in neurotrophin function and the mechanism for receptor tyrosine kinase signaling.

Abnormal polarization of EGF receptors and autocrine stimulation of cyst epithelial growth in human ADPKD

The underlying mechanism of the hyperproliferative response of human autosomal dominant polycystic kidney disease (ADPKD) epithelia was studied. Epidermal growth factor (EGF) protein is highly expressed in ADPKD cyst epithelia in vivo, and primary cultures are hyperesponsive to mitogenic stimulation by EGF in vitro. Doses of > 1 ng/ml EGF were highly mitogenic to ADPKD epithelia. 3H-labeled thymidine proliferation assays showed that cyst fluids and ADPKD epithelial cell-conditioned media also stimulated renal epithelial cell proliferation and contained EGF immunoreactivity (6, 30, and 37 kDa) as detected by Western blots. Radioimmunoassays detected mean levels of 2.87 and 1.4 ng/ml EGF in cyst fluids from early (proliferative) and end-stage ADPKD cysts, respectively. Scatchard analysis of 125I-labeled EGF binding to apical and basolateral membrane showed high-affinity binding to basolateral membranes of normal and ADPKD kidneys but additional unique high-affinity receptor binding to apical membranes of ADPKD but not normal kidneys. Cross-linking analysis and antiphosphotyrosine Western analysis demonstrated functionally active apical EGF receptors at 150-170 kDa. These results suggest mediation of cyst expansion via an autocrine loop involving EGF synthesis and processing by cyst epithelial cells, apical secretion into cyst lumens, and subsequent binding to and phosphorylation of apical membrane EGF receptors. These findings are consistent with a membrane protein polarization defect in ADPKD cyst epithelia.

Systematic review of intraoperative cholangiography in cholecystectomy

BACKGROUND

Intraoperative cholangiography (IOC) is used to detect choledocholithiasis and identify or prevent bile duct injury. The aim of this study was systematically to review the randomized clinical trials of IOC for these two indications.

METHODS

MEDLINE, Embase, the Cochrane Library, clinicaltrials.gov and the World Health Organization database of clinical trials were searched systematically (January 1980 to February 2011) to identify trials. Two authors performed the literature search and extracted data independently. Primary endpoints were bile duct injury and retained common bile duct (CBD) stones diagnosed at any stage after surgery. Preliminary meta-analysis was undertaken, but the trials were too methodologically heterogeneous and the outcome events too infrequent to allow meaningful meta-analysis.

RESULTS

Eight randomized trials were identified including 1715 patients. Six trials assessed the value of routine IOC in patients at low risk of choledocholithiasis. Two trials randomized all patients (including those at high risk) to routine or selective IOC. Two cases of major bile duct injury were reported, and 13 of retained CBD stones. No trial demonstrated a benefit in detecting CBD stones. IOC added a mean of 16 min to the total operating time.

CONCLUSION

There is no robust evidence to support or abandon the use of IOC to prevent retained CBD stones or bile duct injury. Level 1 evidence for IOC is of poor to moderate quality. None of the trials, alone or in combination, was sufficiently powered to demonstrate a benefit of IOC. Further small trials cannot be recommended.

The K+ channel, Kv2.1, is apposed to astrocytic processes and is associated with inhibitory postsynaptic membranes in hippocampal and cortical principal neurons and inhibitory interneurons

A variety of voltage-gated ion channels are expressed on principal cell dendrites and have been proposed to play a pivotal role in the regulation of dendritic excitability. Previous studies at the light microscopic level demonstrated that the K+ channel subunit Kv2.1 expression was polarized to the cell soma and dendrites of principal neurons throughout the central nervous system. Here, using double immunostaining we now show that Kv2.1 protein is similarly expressed in the majority of cortical and hippocampal parvalbumin, calbindin and somatostatin-containing inhibitory interneurons. At the electron microscopic level Kv2.1 immunoreactivity was primarily observed on the plasma membrane of the somata and proximal dendrites of both principal neurons and inhibitory interneurons; expression was low on smaller dendritic branches, and absent on axons and presynaptic terminals. Kv2.1 subunit expression was highly concentrated on the cell surface membrane immediately facing astrocytic processes. Kv2.1 expression was also concentrated in specific cytoplasmic compartments and on the subsurface cisterns underlying the plasma membrane facing astrocytes. In addition, Kv2.1 subunit immunoreactivity was associated with postsynaptic densities of a fraction of inhibitory symmetric synapses; while expression at asymmetric synapses was rare. These data demonstrate that channels formed by Kv2.1 subunits are uniquely positioned on the soma and principal dendrites of both pyramidal cells and inhibitory interneurons at sites immediately adjacent to astrocytic processes. This close apposition to astrocytes will ensure a rapid removal and limit the influence of K+ released into the extracellular space. This expression pattern suggests that channels formed by Kv2.1 are poised to provide a role in the regulation of neuronal dendritic excitability.

Structure--activity relationships of 1-(2-Deoxy-2-fluoro-beta-L-arabinofuranosyl)pyrimidine nucleosides as anti-hepatitis B virus agents

Since 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU) has been shown to be a potent anti-HBV agent in vitro, it was of interest to study the structure-activity relationships of related nucleosides. Thus, a series of 1-(2-deoxy-2-fluoro-beta-L-arabinofuranosyl)pyrimidine nucleosides have been synthesized and evaluated for antiviral activity against HBV in 2.2.15 cells. For this study, L-ribose was initially used as the starting material. Due to the commercial cost of L-ribose, we have developed an efficient procedure for the preparation of L-ribose derivative 6. Starting from L-xylose, 6 was obtained in an excellent total yield (70%) through the pyridinium dichromate oxidation of the 3-OH group followed by stereoselective reduction with NaBH4. It was further converted to the 1,3,5-tri-O-benzoyl-2-deoxy-2-fluoro-alpha-L-arabinofuranose (10), which was then condensed with various 5-substituted pyrimidine bases to give the nucleosides. Among the compounds synthesized, the lead compound, L-FMAU (13), exhibited the most potent anti-HBV activity (EC50 0.1 microM). None of the other uracil derivatives showed significant anti-HBV activity up to 10 microM. Among the cytosine analogues, the cytosine (27) and 5-iodocytosine (35) derivatives showed moderately potent anti-HBV activity (EC50 1.4 and 5 microM, respectively). The cytotoxicity of these nucleoside analogues has also been assessed in 2.2.15 cells as well as CEM cells. None of these compounds displayed any toxicity up to 200 microM in 2.2.15 cells. Thus, compound 13 (L-FMAU), 27, and 35 showed a selectivity of over 2000, 140, and 40, respectively.

Testosterone, preoptic dopamine, and copulation in male rats

Steroid hormones prime neural circuits for sexual behavior, in part by regulating enzymes, receptors, or other proteins affecting neurotransmitter function. Dopamine facilitates male sexual behavior in numerous species and is released before and/or during copulation in three integrative neural systems. The nigrostriatal system enhances readiness to respond; the mesolimbic system promotes many appetitive behaviors; the medial preoptic area (MPOA) contributes to sexual motivation, genital reflexes, and copulation. We have reported a consistent relationship between precopulatory dopamine release in the MPOA, when an estrous female was behind a perforated barrier, and the ability to copulate after the barrier was removed. Recent, but not concurrent, testosterone was necessary for the precopulatory dopamine response and copulation. The deficit in MPOA dopamine release in castrates was observed in basal conditions as well as the sexual context. However, dopamine in tissue punches from castrates was higher than in intact males. Because tissue levels represent primarily stored neurotransmitter, dopamine appeared to have been synthesized normally, but was not being released. Amphetamine induced greater dopamine release in castrates, again suggesting excessive dopamine storage. The decreased release may result from decreased activity of nitric oxide synthase in the MPOA of castrates. A marker for this enzyme showed lower activity in castrates than in intact males. Finally, blocking nitric oxide synthase in intact males blocked the copulation-induced release of dopamine in the MPOA. Therefore, one means by which testosterone may promote copulation is by upregulating nitric oxide synthesis in the MPOA, which in turn enhances dopamine release.

Glyoxal and methylglyoxal trigger distinct signals for map family kinases and caspase activation in human endothelial cells

Carbonyl compounds with diverse carbon skeletons may be differentially related to the pathogenesis of vascular diseases. In this study, we compared intracellular signals delivered into cultured human umbilical vein endothelial cells (HUVECs) by glyoxal (GO) and methylglyoxal (MGO), which differ only by a methyl group. Depending on their concentrations, GO and MGO promoted phosphorylations of ERK1 and ERK2, which were blocked by the protein-tyrosine kinase (PTK) inhibitors herbimycin A and staurosporine, thereby being PTK-dependent. GO and MGO also induced phosphorylations of JNK, p38 MAPK, and c-Jun, either PTK-dependently (GO) or -independently (MGO). Next, we found that MGO, but not GO, induced degradation of poly(ADP-ribose) polymerase (PARP) as the intracellular substrate of caspase-3. Curcumin and SB203580, which inhibit JNK and p38 MAPK signaling pathways, but not herbimycin A/staurosporine, prevented the MGO-induced PARP degradation. We then found that MGO, but not GO, reduced the intracellular glutathione level, and that cysteine, but not cystine, inhibited the MGO-mediated activation of ERK, JNK, p38 MAPK, or c-Jun more extensively than did lysine or arginine. In addition, all the signals triggered by GO and MGO were blocked by amino guanidine (AG), which traps carbonyls. These results demonstrated that GO and MGO triggered two distinct signal cascades, one for PTK-dependent control of ERK and another for PTK-independent redox-linked activation of JNK/p38 MAPK and caspases in HUVECs, depending on the structure of the carbon skeleton of the chemicals.

Case-control study of residential radon and lung cancer in Winnipeg, Manitoba, Canada

A case-control study of lung cancer in relation to exposure to radon in homes in Winnipeg, Manitoba, Canada, was conducted during 1983-1990. In total, 738 individuals with histologically confirmed incident cases of lung cancer were interviewed, along with 738 controls matched on age (+/- 5 years) and sex. Radon dosimeters were placed in all residences in which the study subjects had reported living within the Winnipeg metropolitan area for at least 1 year. Radon dosimetry was done by means of integrated alpha-track measurements over a 1-year period. In the homes monitored, the average level of radon-222 was about 120 becquerels (Bq)/m3 in the bedroom area and 200 Bq/m3 in the basement. After adjusting for cigarette smoking and education, no increase in the relative risk for any of the histologic types of lung cancer observed among the cases was detected in relation to cumulative exposure to radon.

Glucocorticoids induce proteasome C3 subunit expression in L6 muscle cells by opposing the suppression of its transcription by NF-kappa B

Muscle wasting in catabolic conditions results from activation of the ubiquitin-proteasome proteolytic pathway by a process that requires glucocorticoids and is generally associated with increased levels of mRNAs encoding components of this proteolytic system. In L6 muscle cells, dexamethasone stimulates proteolysis and increases the amount of the proteasome C3 subunit protein by augmenting its transcription. Transfection studies with human C3 promoter-luciferase reporter genes and electrophoretic mobility shift assays revealed that a NF-kappaB.protein complex containing Rel A is abundant in L6 muscle cell nuclei. Glucocorticoids stimulate C3 subunit expression by antagonizing the interaction of this NF-kappaB protein with an NF-kappaB response element in the C3 subunit promoter region. Dexamethasone also increased the cytosolic amounts of the NF-kappaB p65 subunit and the IkappaBalpha inhibitor proteins in L6 cells. Incubation of L6 cells with a cytokine mixture not only increased the amount of activated NF-kappaB but also decreased C3 promoter activity and lowered endogenous C3 subunit mRNA. Thus, NF-kappaB is a repressor of C3 proteasome subunit transcription in muscle cells, and glucocorticoids stimulate C3 subunit expression by opposing this suppressor action.

Umbilical cord blood cells capable of engrafting in primary, secondary, and tertiary xenogeneic hosts are preserved after ex vivo culture in a noncontact system

This report describes stroma-based and stroma-free cultures that maintain long-term engrafting hematopoietic cells for at least 14 days ex vivo. Umbilical cord blood (UCB) CD34(+) cells were cultured in transwells above AFT024 feeders with fetal-liver-tyrosine-kinase (FL) + stem cell factor (SCF) + interleukin 7 (IL-7), or FL + thrombopoietin (Tpo). CD34(+) progeny were transplanted into nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice or preimmune fetal sheep. SCID repopulating cells (SRC) with multilineage differentiation potential were maintained in FL-SCF-IL-7 or FL-Tpo containing cultures for up to 28 days. Marrow from mice highly engrafted with uncultured or expanded cells induced multilineage human hematopoiesis in 50% of secondary but not tertiary recipients. Day 7 expanded cells engrafted primary, secondary, and tertiary fetal sheep. Day 14 expanded cells, although engrafting primary and to a lesser degree secondary fetal sheep, failed to engraft tertiary recipients. SRC that can be transferred to secondary recipients were maintained for at least 14 days in medium containing glycosaminoglycans and cytokines found in stromal supernatants. This is the first demonstration that ex vivo culture in stroma-noncontact and stroma-free cultures maintains "long-term" engrafting cells, defined by their capacity to engraft secondary or tertiary hosts. (Blood. 2001;97:3441-3449)