Induced cerebral hypothermia reduces post-hypoxic loss of phenotypic striatal neurons in preterm fetal sheep

Perinatal hypoxic-ischemic injury of the basal ganglia is a significant cause of disability in premature infants. Prolonged, moderate cerebral hypothermia has been shown to be neuroprotective after experimental hypoxia-ischemia; however, it has not been tested in the preterm brain. We therefore examined the effects of severe hypoxia and the potential neuroprotective effects of delayed hypothermia on phenotypic striatal neurons. Preterm (0.7 gestation) fetal sheep received complete umbilical cord occlusion for 25 min followed by cerebral hypothermia (fetal extradural temperature reduced from 39.4+/-0.3 degrees C to 29.5+/-2.6 degrees C) from 90 min to 70 h after the end of occlusion. Hypothermia was associated with a significant overall reduction in striatal neuronal loss compared with normothermia-occlusion fetuses (mean+/-SEM, 5.5+/-1.2% vs. 38.1+/-6.5%, P<0.01). Immunohistochemical studies showed that occlusion resulted in a significant loss of calbindin-28 kd, glutamic acid decarboxylase isoform 67 and neuronal nitric oxide synthase-immunopositive neurons (n=7, P<0.05), but not choline acetyltransferase-positive neurons, compared with sham controls (n=7). Hypothermia (n=7) significantly reduced the loss of calbindin-28 kd and neuronal nitric oxide synthase, but not glutamic acid decarboxylase-immunopositive neurons. In conclusion, delayed, prolonged moderate head cooling was associated with selective protection of particular phenotypic striatal projection neurons after severe hypoxia in the preterm fetus. These findings suggest that head cooling may help reduce basal ganglia injury in some premature babies.

In Vitro Study of Salmonella enteritidis and Salmonella typhimurium Definitive Type 104: Survival in Egg Albumen and Penetration through the Vitelline Membrane

Salmonella enteritidis and Salmonella typhimurium definitive type 104 (DT104) have been detected in the chicken oviduct, and their survival in egg albumen at the chicken body temperature of 42 degrees C may be important in oviductal and transovarian contamination of intact shell eggs. Eight S. enteritidis and 24 S. typhimurium DT104 strains were tested for their in vitro survival in egg albumen. The concentration of the organisms declined more rapidly when incubated at 42 degrees C than at 37 degrees C and dropped to nondetectable levels within 96 h at the higher, but not at the lower, temperature. In another experiment, 3 S. enteritidis and 3 S. typhimurium DT104 strains were randomly selected, and dosages of 20 and 200 cells of each strain were inoculated onto the vitelline membranes of egg yolks, which were then submerged in the original albumen and incubated for 24 h at 42 degrees C. Under these conditions, the organisms survived in albumen but did not penetrate the vitelline membrane. However, in a similar experiment, penetration did occur when the specimens were incubated at 30 degrees C for 72 h. The results suggest that low numbers of S. enteritidis and S. typhimurium DT104 can be expected to survive in egg albumen during the 24-h period of egg formation in the oviduct but would be unlikely to invade the yolk.before oviposition. However, depending on storage conditions following oviposition, S. enteritidis, as well as S. typhimurium DT104, could survive longer and may eventually invade the egg yolks.

High frequency of OTOF mutations in Chinese infants with congenital auditory neuropathy spectrum disorder

Auditory neuropathy spectrum disorder (ANSD) is one of the most common diseases leading to hearing and speech communication barriers in infants and young children. The OTOF gene is the first gene identified for autosomal recessive non-syndromic ANSD, and patients with OTOF mutations have shown marked improvement of auditory functions from the cochlear implantation, but the true involvement of OTOF mutations in Chinese ANSD patients is still unknown which precludes the effective management of this disease. Here, we investigated the contribution of OTOF mutations to congenital ANSD patients in China. In all, 37 infants and young Children with ANSD were screened for all the exons of OTOF gene, of them 34 patients had no neonatal risk factors who were considered as congenital ANSD. The clinical manifestation and audiometric features were also investigated and compared in patients with and without OTOF mutations. In all, 14 of these subjects were shown to carry two or three mutant alleles of OTOF with the high frequency of 41.2% in congenital ANSD patients. In total, 15 novel pathogenic mutations and 10 reported mutations were identified. Our results confirmed that mutations in OTOF gene were a major cause of congenital ANSD in China. Identification of OTOF mutations can facilitate diagnosis, clinical intervention and counseling for congenital ANSD.

Ohr Protects Corynebacterium glutamicum against Organic Hydroperoxide Induced Oxidative Stress

Ohr, a bacterial protein encoded by the Organic Hydroperoxide Resistance (ohr) gene, plays a critical role in resistance to organic hydroperoxides. In the present study, we show that the Cys-based thiol-dependent Ohr of Corynebacterium glutamicum decomposes organic hydroperoxides more efficiently than hydrogen peroxide. Replacement of either of the two Cys residues of Ohr by a Ser residue resulted in drastic loss of activity. The electron donors supporting regeneration of the peroxidase activity of the oxidized Ohr of C. glutamicum were principally lipoylated proteins (LpdA and Lpd/SucB). A Δohr mutant exhibited significantly decreased resistance to organic hydroperoxides and marked accumulation of reactive oxygen species (ROS) in vivo; protein carbonylation was also enhanced notably. The resistance to hydrogen peroxide also decreased, but protein carbonylation did not rise to any great extent. Together, the results unequivocally show that Ohr is essential for mediation of organic hydroperoxide resistance by C. glutamicum.

Urinary sediment ICAM-1 level in lupus nephritis

BACKGROUND

Urinary intercellular adhesion molecule-1 (ICAM-1) level is potentially a valuable biomarker of lupus nephritis (LN), but because ICAM-1 is a cell-surface molecule, soluble ICAM-1 level in urinary supernatant measured by ELISA may not be biologically relevant.

METHODS

The ICAM-1 level in urine sediment of 12 LN patients, 10 patients with pauci-immune necrotizing glomerulonephritis (NecGN), and six healthy controls were determined with a polymerase chain reaction (PCR)-based assay. The urinary sediment levels of miR-221, miR-222, miR-339-3P and miR-339-5P, which are involved in the regulation of ICAM-1 production, were also quantified.

RESULTS

LN patients had lower urinary sediment ICAM-1 levels than the other two groups (overall p = 0.034). In addition, urinary sediment ICAM-1 level inversely correlated with the estimated glomerular filtration rate (GFR) (r = -0.474, p = 0.026) but not other markers of lupus activity, or urinary sediment levels of miR-221, miR-222, miR-339-3P, or miR-339-5P. However, serum anti-dsDNA level inversely correlated with urinary sediment levels of miR-221 (r = -0.591, p = 0.043) and miR-222 (r = -0.689, p = 0.013), while urinary sediment miR-221 level also correlated with serum C3 level (r = 0.658, p = 0.02).

CONCLUSIONS

We conclude that urinary sediment ICAM-1 level was significantly reduced in LN, and the level inversely correlated with renal function. Urinary sediment miR-221 and miR-222 levels correlate with lupus disease activity and may serve as biomarkers of LN.

Reactivity of calix-tetrapyrrole SmII and SmIII complexes with acetylene: isolation of an "N-confused" calix-tetrapyrrole ring

The nature of the substituents present on the calix-tetrapyrrole tetra-anion ligand [[R2C(C4H2N)]4]4- (R = [-(CH2)5-]0.5, Et) determines the type of reactivity of the corresponding SmII compounds with acetylene. With R = [-(CH2)5-]0.5, dehydrogenation occurred to yield the nearly colorless dinuclear diacetylide complex [[[[-(CH2)5-]4-calix-tetrapyrrole]SmIII]2(mu-C2Li4)].THF as the only detectable reaction product. Conversely, with R = Et, acetylene coupling in addition to dehydrogenation resulted in the formation of a dimeric butatrienediyl enolate derivative [[(Et8-calix-tetrapyrrole)SmIII[Li[Li(thf)]2(mu-OCH=CH2)]]2(mu,eta2,eta'2-HC=C=C=CH)]. Reaction of the trivalent hydride [(Et8-calix-tetrapyrrole)(thf)SmIII[(mu-H)[Li(thf)]]2 or of the terminally bonded methyl derivative [(Et8-calix-tetrapyrrole)(CH3)SmIII[[Li(thf)]2[Li(thf)2](mu3-Cl)]] with acetylene resulted in a mixture of the carbide [[(Et8-calix-tetrapyrrole)SmIII]2(mu-C2Li4)].Et2O with the dimerization product [[(Et8-calix-tetrapyrrole)SmIII[Li[Li(thf)]2(mu3-OCH=CH2)]]2-mu,eta2,eta'2-HC=C=C=CH)]. The same reaction also yielded a third product, a trivalent complex [[(Et8-calix-tetrapyrrole)SmIII[Li(thf)2]]2], in which the macrocycle was isomerized by shifting the ring attachment of one of the four pyrrole rings.

FMNL2 destabilises COMMD10 to activate NF-κB pathway in invasion and metastasis of colorectal cancer

BACKGROUND

Diaphanous-related formins (DRFs), actin necleator, have been known to participate in the progression of cancer cells. We previously reported that FMNL2 (Formin-like2), a member of DRFs, was a positive regulator in colorectal cancer (CRC) metastasis, yet proteins and pathways required for the function of this pro-invasive DRFs remain to be identified.

METHODS

The relationship between FMNL2 and COMMD10 was examined using Co-IP, GST pull-down, immunofluorescence and in vitro ubiquitination assay. The in vitro and in vivo function of COMMD10 in CRC was evaluated using CCK-8 proliferation assay, plate colony formation, cell cycle, apoptosis and animal models. The inhibition of NF-κB signalling by COMMD10 was detected using dual-luciferase reporter assay and western blotting. Co-IP, GST pull-down and nuclear protein extraction assay were performed to evaluate the effect on p65 by COMMD10. Real-time PCR and western blotting were performed to detect expressions of FMNL2, COMMD10 and p65 in paired tissues.

RESULTS

FMNL2 targets COMMD10 for ubiquitin-mediated proteasome degradation in CRC cells. COMMD10 targets p65 NF-κB (nuclear factor-κB) subunit and reduces its nuclear translocation, thereby leading to the inactivation of NF-κB pathway and suppression of CRC invasion and metastasis. Inhibition of NF-κB signalling by COMMD10 is necessary for FMNL2-mediated CRC cell behaviours. Downregulation of COMMD10 predicts poor prognosis of CRC patients. The expressions of FMNL2, COMMD10 and p65 are highly linked in CRC tissues.

CONCLUSIONS

These data demonstrate that the FMNL2/COMMD10/p65 axis acts as a critical regulator in the maintenance of metastatic phenotypes and is strongly associated with negative clinical outcomes.

Comparison of tetragonal and cubic tin as anode for Mg ion batteries

Using first-principles calculation based on density functional theory, diffusion of Mg atom into α- and β-Sn was investigated. The diffusion barriers are 0.395 and 0.435 eV for an isolated Mg atom in the α- and β-Sn, respectively. However, the diffusion barriers of the Mg atom decrease in the α-Sn, whereas they increase in the β-Sn, when an additional Mg atom was inserted near the original diffusing Mg atom, which is mainly due to strong binding of Mg-Mg atoms in the β-Sn. Therefore, it is better to use the α-Sn, rather than the β-Sn, as an anode material for Mg ion batteries.

Association between indoor air pollution, tobacco smoke and tuberculosis: an updated systematic review and meta-analysis

OBJECTIVE

This study aims to further quantify evidence of the association between exposure to indoor air pollution (IAP), tobacco smoke etc., on the one hand and the risk of contracting tuberculosis (TB) on the other.

STUDY DESIGN

This was a systematic review and meta-analysis of articles published between June 2014 and February 2020 in PubMed, Web of Science, among others.

METHODS

We only included studies that controlled for confounders, screened both the exposed and unexposed study participants, and passive smoking studies that limited the study population to non-smokers. Quality of studies was assessed using the Newcastle-Ottawa scale. The analysis was conducted using STATA, and pooled effect sizes were calculated using the random-effects model, and heterogeneity was tested for using the Cochran Q test and I2 statistic.

RESULTS

A total of 26 articles were included in the final analysis. There was an increased risk of contracting TB among people exposed to IAP (risk ratio [RR] = 1.68, 95% confidence interval [CI] 1.108-2.542). We also observed a two-fold increase in the risk of contracting TB from exposure to secondhand tobacco smoke (RR = 2.15, 95%CI 1.419-3.242). Tobacco smoking doubled the risk of contracting TB (RR = 2.67, 95%CI 2.017-3.527). Furthermore, studies that used microbiological tests showed a higher RR compared to those that used other TB diagnostic methods.

CONCLUSION

Exposure to IAP and secondhand tobacco smoke increases the risk of contracting TB. Various disease prevention campaigns should include IAP awareness and encourage a shift to cleaner sources of energy.

Unique biochemical, cytotoxic, and antitumor activity of camptothecin and 4beta-amino-4'-O-demethylepipodophyllotoxin conjugates

Two compounds having a camptothecin (CPT) analog conjugated to the 4beta-amino-4'-O-demethylepipodophyllotoxin analog were evaluated for their biochemical and biological activities. W1[camptothecin-(para)-4beta-amino-4'-O-demethylepipodophyllotoxin] had no activity against topoisomerase II (TOP II), but inhibited topoisomerase I (TOP I) with an IC(50) value 2-fold higher than CPT. W2 [camptothecin-(ortho)-4beta-amino-4'-O-demethylepipodophyllotoxin] had inhibitory activity against TOP I and TOP II with IC(50) values 1.5-fold higher than either CPT or etoposide (VP-16). Both conjugates had similar cytotoxicity against the KB cell line, although the protein-linked DNA breaks (PLDBs) generated by W2 in KB cells were about 4-fold more than those of W1. No cross-resistance with the two conjugates was seen in a VP-16-resistant KB subline, which showed down-regulation of TOP II and overexpression of the multiple drug resistance-associated protein, or in a vincristine-resistant KB subline with overexpression of gp-170/mdr-1. The CPT-resistant KB variant (KB CPT 100), which has a reduction in TOP I content and another mechanism that occurs post-PLDB formation, was partially resistant to both compounds. W1 was not affected by this post-PLDB resistance mechanism. Cell cycle analysis demonstrated that W1 and W1 had similar cell cycle effects on KB and KB CPT 100 cells, which accumulated in S-phase upon drug treatment. These results suggested that W1 and W2 exerted their cytotoxicity through TOP I. In CPT-resistant cells, however, an unidentified target also may be involved in the cytotoxic action of W1 and TOP II may still be a target for W1. In vivo, W1 was more effective against the growth of human prostate cancer cells in nude mice than VP-16, CPT, or W2. Given its antitumor activity and unique biochemical mechanism of action, W1 warrants exploration as an antitumor compound.

Intracerebral transportation and cellular localisation of insulin-like growth factor-1 following central administration to rats with hypoxic-ischemic brain injury

Insulin-like growth factor-1 (IGF-1) has been shown to be neuroprotective when administered centrally following hypoxic-ischemic (HI) brain injury. However, the cerebral distribution and site of action of IGF-1 after intracerebroventricular (i.c.v.) administration are not known. A unilateral HI brain injury was induced in adult rats by a modified Levine method. Either 3H-IGF-1 alone, or in combination with unlabelled IGF-1, was administered into the lateral ventricle 2 h after injury. The activity of 3H-IGF-1 signal in the potentially injured cortex was compared between two treatment groups using image analysis. The regional distribution and cellular localisation of 3H-IGF-1 were examined autoradiographically in potentially injured hemispheres at 0.5 and 6 h after administration. Tritiated IGF-1 was detected predominantly in the pia mater, perivascular spaces and subcortical white matter tracts 0.5 h after administration and decreased by 6 h (p<0.05). The signals associated with the perivascular spaces and pia mater were not blocked by unlabelled IGF-1, suggesting non-saturable binding in these brain areas. IGF-1 signal was co-localised with IGF binding protein (IGFBP)-2 immunostaining in the white matter tracts where the signal was blocked by unlabelled IGF-1, suggesting competitive association. IGF-1 signal associated with neurons and glia was maximal in the cerebral cortex and less in the CA1-2 subregion of the hippocampus which were blocked by unlabelled IGF-1 (p<0.05). The signals from cortical neurons did not decrease 6 h after administration, suggesting specific and persistent binding to these cells. Our results indicate that centrally administered IGF-1 can be translocated to neurons and glia via the perivascular circulation and the ependymal cell-white matter tract pathways.

The effect of aging on adaptive eye-hand coordination

Perceptual-motor adaptability of older adults (65 and older) was assessed. Participants in two groups (younger, 20-36 years, and older, 67-87 years) pointed 100 times at a straight-ahead visual target while looking through laterally displacing prisms, with the hand visible early in the pointing movement. Aftereffect tests were administered after adaptation. Each group was then split into decay and readaptation subgroups in which respective treatments were given twice. After each treatment, aftereffect tests were readministered. Eye-hand total shift was significantly smaller for older participants, proprioceptive shift was not statistically smaller for older participants, and visual shift did not appear. Readaptation produced greater reduction in aftereffects than did decay; this effect was the same for both groups. The main conclusion is that perceptual-motor adaptability declines with advancing age.

Synergy of the mechanical, antifouling and permeation properties of a carbon nanotube nanohybrid membrane for efficient oil/water separation

For water treatment applications, fabricating a high permeation flux membrane with super-strong mechanical strength and excellent long-term antifouling properties remains a great challenge. In this study, robust, antifouling carbon nanotube (CNT) nanohybrid membranes have been fabricated for oil/water separation. Polyethyleneimine (PEI) with abundant amino groups and a hyperbranched structure is utilized to construct a nanocoating on a CNT surface to enhance their hydrophilicity through multiple interactions between PEI and CNTs. Secondly, the vacuum-assisted self-assembly method is utilized to fabricate free-standing membranes by filtration of CNT dispersions. Finally, trimesoyl chloride (TMC) is utilized to post-modify membranes to enhance the mechanical strength and hydrophilicity and change the surface charge through reaction between amino groups and acyl chloride groups as well as hydrolysis of acyl chloride groups into carboxyl groups. The controlled stacking of CNTs renders membranes with a hierarchical nanostructure and a high porosity, leading to high water flux. The physical and chemical crosslinking renders membranes with high mechanical strength, as measured by atomic force microscopy (AFM) and tensile strength tests. The high hydrophilicity and negatively charged surface render membranes with good antifouling properties, as evaluated by filtration experiments of various oil-in-water emulsions. This study may reveal the great prospects of CNT-based membranes with superior comprehensive properties in water treatment relevant applications.

The Egr-1 gene is induced by epidermal growth factor in ECV304 cells and primary endothelial cells

The early growth response (Egr)-1 transcription factor serves to couple changes in the extracellular environment to alterations in gene expression. An understanding of the mechanisms that underlie Egr-1 gene regulation should provide important insights into how environmental signals are transduced by endothelial cells. The aim of the present study was to determine whether epidermal growth factor (EGF) induces Egr-1 expression in endothelial cells. In ECV304 cells, Egr-1 mRNA and protein levels were increased in response to EGF. In stable transfection assays, the 1,200-bp promoter of the mouse Egr-1 gene contained information for EGF response via a protein kinase C-independent, mitogen-activated protein kinase-dependent pathway. The endogenous Egr-1 gene was similarly responsive to EGF in primary human umbilical vein endothelial cells, human coronary artery endothelial cells, and rat fat pad endothelial cells, but not in bovine aortic endothelial cells, calf pulmonary artery endothelial cells, or PY-4-1 endothelial cells. Together, these results suggest that the Egr-1 gene is responsive to EGF in a subset of endothelial cells.

Repair of DNA double-strand breaks and radiosensitivity to killing in an isogenic group of p53 mutant cell lines

PURPOSE

Accumulation of the p53 protein can result in G1 arrest that may facilitate DNA repair, or alternatively, it may lead to apoptosis. Mutations that alter p53's ability to mediate these responses are expected to alter cell radiosensitivity to killing. However, the relationship between p53 status and cell radiosensitivity has proven to be complex. Several studies have suggested that p53 mutations are associated with increased radioresistance to killing, while others have shown no such correlation. These differences may be derived from the fact that different mutations of p53 exert different effects on cell radiosensitivity.

METHODS AND MATERIALS

To address this question, we examined a group of isogenic cell lines that express different "hot spot" mutant forms of p53. These cells were generated from human osteosarcoma (SAOS) cells, a p53 null cell line, by transfection with vectors expressing different p53 mutants. Vectors with the following p53 mutations were utilized: 143Ala, 175His, 248Try, 273His, and 281Gly. As controls, we used the original SAOS cells and cells transfected with the vector alone. Results were compared to those obtained with a cell line expressing wild-type p53 (wt p53). Radiosensitivity to killing was determined in the exponential phase of growth by measuring loss of colony-forming ability. Induction and repair of DNA double-strand breaks (dsb) was measured in irradiated cells using pulsed-field gel electrophoresis. Apoptosis was assessed using morphologic evaluation of DAPI-stained cells after treatment either with radiation or paclitaxel.

RESULTS

Transfected SAOS-2 cell lines expressed a mutant form of p53 that could not be induced by radiation, and which was transcriptionally inactive. Among the 7 cell lines studied, we observed no difference in cellular radiosensitivity to killing (p = NS). When examining DNA repair, no difference in either the induction or repair of DNA dsb was noted in any of the cell lines studied (p = NS). Also, induction of apoptosis, either after exposure to radiation or paclitaxel, was low, and similar in all cell lines (p = NS). Non-isogenic cells expressing wt p53 were more radioresistant to killing by radiation, but showed similar kinetics of dsb rejoining.

CONCLUSION

The results suggest that expression of different p53 mutants does not alter the yields of radiation-induced dsb, or the ability of cells to repair this type of lesion. In addition, the same p53 mutants do not affect cellular radiosensitivity to killing, or the induction of apoptosis after exposure to radiation or paclitaxel.

Changes in facial appearance after maxillomandibular advancement for severe obstructive sleep apnoea hypopnoea syndrome in Chinese patients: a subjective and objective evaluation

This study evaluates the outcome and change in facial appearance after maxillomandibular advancement (MMA) in Chinese adults with severe obstructive sleep apnoea hypopnoea syndrome (OSAHS). Twelve patients underwent MMA with adjunctive procedures for severe OSAHS. All underwent physical examination, Epworth Sleepiness Scale evaluation, cephalometry, polysomnography, and facial photographic assessment before and 6 months after MMA. The aesthetic plane (relationship of nose, lips, and chin) was used to judge soft tissue facial profile change after MMA. Postoperative cephalometric data were compared with normal occlusive standards and aesthetic norms. Pre- and postoperative aesthetic appearance was evaluated by 100 lay people using a 10-point visual analogue scale. The maxillomandibular complex (MMC) was advanced 5-10 mm (mean 7.4 mm). The success rate was 83%. All patients were satisfied with the functional and aesthetic results. Postoperative SNA, SNB, and posterior airway space increased and mandibular plane-to-hyoid distance decreased significantly in all patients. The lower lip was closer to EP than the preoperative and normal occlusive standard. In 11 of 12 patients, the lay aesthetic scores were significantly higher postoperatively. MMA is effective for Chinese adults with severe OSAHS. In most patients, facial appearance was more attractive after MMC advancement of 5-10 mm.

Fas/FasL in the immune pathogenesis of severe aplastic anemia

Fas/FasL protein expression of bone marrow hematopoietic cells was investigated in severe aplastic anemia (SAA) patients. Fas expression was evaluated in CD34(+), GlycoA(+), CD33(+), and CD14(+) cells labeled with monoclonal antibodies in newly diagnosed and remission SAA patients along with normal controls. FasL expression was evaluated in CD8(+) cells in the same manner. In CD34(+) cells, Fas expression was significantly higher in the newly diagnosed SAA group (46.59 ± 27.60%) than the remission (6.12 ± 3.35%; P < 0.01) and control (8.89 ± 7.28%; P < 0.01) groups. In CD14(+), CD33(+), and GlycoA(+) cells, Fas levels were significantly lower in the newly diagnosed SAA group (29.29 ± 9.23, 46.88 ± 14.30, and 15.15 ± 9.26%, respectively) than in the remission (47.23 ± 31.56, 67.22 ± 34.68, and 43.56 ± 26.85%, respectively; P < 0.05) and normal control (51.25 ± 38.36, 72.06 ± 39.88, 50.38 ± 39.88%, respectively; P < 0.05) groups. FasL expression of CD8(+) cells was significantly higher in the newly diagnosed SAA group (89.53 ± 45.68%) than the remission (56.39 ± 27.94%; P < 0.01) and control (48.63 ± 27.38%; P <0.01) groups. No significant differences were observed between the remission and control groups. FasL expression in CD8(+) T cells was significantly higher in newly diagnosed patients, and CD34(+), CD33(+), CD14(+), and GlycoA(+) cells all showed Fas antigen expression. The Fas/FasL pathway might play an important role in excessive hematopoietic cell apoptosis in SAA bone marrow. Furthermore, CD34(+) cells are likely the main targets of SAA immune injury.

Evidence for an S-phase checkpoint regulating DNA replication after heat shock: a review

Exposure of cells to heat inhibits a number of nuclear activities associated with semi-conservative replication of DNA including the incorporation of radiolabelled precursors into acid-insoluble DNA, the initiation of new replicons, the elongation of the DNA fibre at the replication fork, the synthesis and deposition of new histones into chromatin and the reorganization of nascent DNA into mature chromatin. These effects are likely to underlie the heat sensitivity of S-phase cells and may contribute to the radiosensitization observed in this phase of the cell cycle. While some of these effects may be explained as 'passive' consequences of heat-induced damage on chromatin structures experiments reviewed here point to the activation of a checkpoint as a contributing factor to the observed inhibition of DNA replication. Activation of a heat responsive S-phase checkpoint targets the activity of RPA via interaction with nucleolin. Nucleolin, a major nucleolar protein, is found normally sequestered in the nucleolus. Exposure of cells to heat causes a rapid translocation of nucleolin from the nucleolus into the nucleoplasm that enables RPA/nucleolin interaction. This interaction inhibits functions of RPA associated with the initiation of DNA replication and contributes to the immediate inhibition of DNA synthesis observed after heat shock. The results suggest that the nucleolus serves as a sequestration centre for the temporary inactivation of regulatory molecules, such as nucleolin, capable of regulating essential cellular functions after heat shock. It is speculated that this regulatory process is integrated in the network of responses that determine cell sensitivity to heat and that it may be involved in heat radiosensitization to killing as well.

Asymmetric Aerogel Membranes with Ultrafast Water Permeation for the Separation of Oil-in-Water Emulsion

Owing to highly porous and low density attributes, aerogels have been actively utilized in catalysis and adsorption processes, but their great potential in filtration requires exploitation. In this study, an asymmetric aerogel membrane is fabricated via one-pot hydrothermal reaction-induced self-cross-linking of poly(vinyl alcohol) (PVA), which exhibits ultrafast permeation for the separation of oil-in-water emulsion. Meanwhile, carbon nanotubes are added to improve the mechanical strength of the aerogel membranes. The self-cross-linking of PVA forms the supporting layer, and the exchange of water and vapor at the interface of PVA solution and air generates the separating layer as well as abundant hydroxyl groups on the membrane surface. The density, porosity, pore size, and wettability of the aerogel membrane can be tuned by the PVA concentration. Owing to high porosity (>95%) and suitable pore size (<85 nm), the aerogel membrane exhibits high rejection (99.0%) for surfactant-stabilized oil-in-water emulsion with an ultrahigh permeation flux of 135.5 × 10³ L m^-2 h^-1 bar^-1 under gravity-driven flow, which is 2 orders of magnitude higher than commercial filtration membranes with similar rejection. Meanwhile, the aerogel membrane exhibits superhydrophilicity, superoleophobicity underwater, and excellent antifouling properties for various surfactant-stabilized oil-in-water emulsions, as indicated by the fact that the flux recovery ratio maintains more than 93% after five cycles of the filtration experiment. The findings in this study may offer a novel idea to fabricate high-throughput filtration membranes.

The catalytic subunit DNA-dependent protein kinase (DNA-PKcs) facilitates recovery from radiation-induced inhibition of DNA replication

Exposure of cells to ionizing radiation inhibits DNA replication in a dose-dependent manner. The dose response is biphasic and the initial steep component reflects inhibition of replicon initiation thought to be mediated by activation of the S-phase checkpoint. In mammalian cells, inhibition of replicon initiation requires the ataxia telagiectasia mutated ( ATM ) gene, a member of the phosphatidyl inositol kinase-like (PIKL) family of protein kinases. We studied the effect on replicon initiation of another member of the PI-3 family of protein kinases, the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) by measuring either total DNA synthesis, or size distribution of nascent DNA using alkaline sucrose gradient centrifugation. Exposure of human cells proficient in DNA-PKcs (HeLa or M059-K) to 10 Gy inhibited replicon initiation in a time-dependent manner. Inhibition was at a maximum 1 h after irradiation and recovered at later times. Similar treatment of human cells deficient in DNA-PKcs (M059-J) inhibited replicon initiation to a similar level and with similar kinetics; however, no evidence for recovery, or only limited recovery, was observed for up to 8 h after irradiation. In addition a defect was observed in the maturation of nascent DNA. Similarly, a Chinese hamster cell line deficient in DNA-PKcs (irs-20) showed little evidence for recovery of DNA replication inhibition up to 6 h after irradiation, whereas the parental CHO cells showed significant recovery and an irs-20 derivative expressing the human DNA-PKcs complete recovery within 4 h. Normal kinetics of recovery were observed in xrs-5 cells, deficient in Ku80; in 180BR cells, deficient in DNA ligase IV; as well as XR-1 cells, deficient in XRCC4, an accessory factor of DNA ligase IV. Since all these cell lines share the DNA double strand break rejoining defect of M059-J and irs20 cells, the lack of recovery of DNA replication in the latter cells may not be attributed entirely to the prolonged presence of unrepaired DNA dsb. We propose that DNA-PKcs, in addition to its functions in the rejoining of DNA dsb and in DNA replication, also operates in a pathway that in normal cells facilitates recovery of DNA replication after irradiation.