Direct isolation of human central nervous system stem cells

Stem cells, which are clonogenic cells with self-renewal and multilineage differentiation properties, have the potential to replace or repair damaged tissue. We have directly isolated clonogenic human central nervous system stem cells (hCNS-SC) from fresh human fetal brain tissue, using antibodies to cell surface markers and fluorescence-activated cell sorting. These hCNS-SC are phenotypically 5F3 (CD133)(+), 5E12(+), CD34(-), CD45(-), and CD24(-/lo). Single CD133(+) CD34(-) CD45(-) sorted cells initiated neurosphere cultures, and the progeny of clonogenic cells could differentiate into both neurons and glial cells. Single cells from neurosphere cultures initiated from CD133(+) CD34(-) CD45(-) cells were again replated as single cells and were able to reestablish neurosphere cultures, demonstrating the self-renewal potential of this highly enriched population. Upon transplantation into brains of immunodeficient neonatal mice, the sorted/expanded hCNS-SC showed potent engraftment, proliferation, migration, and neural differentiation.

Core filaments of the nuclear matrix

The nuclear matrix is concealed by a much larger mass of chromatin, which can be removed selectively by digesting nuclei with DNase I followed by elution of chromatin with 0.25 M ammonium sulfate. This mild procedure removes chromatin almost completely and preserves nuclear matrix morphology. The complete nuclear matrix consists of a nuclear lamina with an interior matrix composed of thick, polymorphic fibers and large masses that resemble remnant nucleoli. Further extraction of the nuclear matrices of HeLa or MCF-7 cells with 2 M sodium chloride uncovered a network of core filaments. A few dark masses remained enmeshed in the filament network and may be remnants of the nuclear matrix thick fibers and nucleoli. The highly branched core filaments had diameters of 9 and 13 nm measured relative to the intermediate filaments. They may serve as the core structure around which the matrix is constructed. The core filaments retained 70% of nuclear RNA. This RNA consisted both of ribosomal RNA precursors and of very high molecular weight hnRNA with a modal size of 20 kb. Treatment with RNase A removed the core filaments. When 2 M sodium chloride was used directly to remove chromatin after DNase I digestion without a preceding 0.25 M ammonium sulfate extraction, the core filaments were not revealed. Instead, the nuclear interior was filled with amorphous masses that may cover the filaments. This reflected a requirement for a stepwise increase in ionic strength because gradual addition of sodium chloride to a final concentration of 2 M without an 0.25 M ammonium sulfate extraction uncovered core filaments.

HIV, but not murine leukemia virus, vectors mediate high efficiency gene transfer into freshly isolated G0/G1 human hematopoietic stem cells

Recent studies have opened the possibility that quiescent, G0/G1 hematopoietic stem cells (HSC) can be gene transduced; lentiviruses (such as HIV type 1, HIV) encode proteins that permit transport of the viral genome into the nucleus of nondividing cells. We and others have recently demonstrated efficient transduction by using an HIV-1-based vector gene delivery system into various human cell types including human CD34(+) cells or terminally differentiated neurons. Here we compare the transduction efficiency of two vectors, HIV-based and murine leukemia virus (MuLV)-based vectors, on untreated and highly purified human HSC subsets that are virtually all in G0/G1. The HIV vector, but not MuLV vector supernatants, transduced freshly isolated G0/G1 HSC from mobilized peripheral blood. Single-step transduction using replication-defective HIV resulted in HSC that expressed the green fluorescent protein (GFP) transgene while retaining their stem cell phenotype; clonal outgrowths of these GFP+ HSC on bone marrow stromal cells fully retained GFP expression for at least 5 weeks. MuLV-based vectors did not transduce resting HSC, as measured by transgene expression, but did so readily when the HSC were actively cycling after culture in vitro for 3 days in a cytokine cocktail. These results suggest that resting HSC may be transduced by lentiviral-based, but not MuLV, vectors and maintain their primitive phenotype, pluripotentiality, and at least in vitro, transgene expression.

Structural analysis of a set of proteins resulting from a bacterial genomics project

The targets of the Structural GenomiX (SGX) bacterial genomics project were proteins conserved in multiple prokaryotic organisms with no obvious sequence homolog in the Protein Data Bank of known structures. The outcome of this work was 80 structures, covering 60 unique sequences and 49 different genes. Experimental phase determination from proteins incorporating Se-Met was carried out for 45 structures with most of the remainder solved by molecular replacement using members of the experimentally phased set as search models. An automated tool was developed to deposit these structures in the Protein Data Bank, along with the associated X-ray diffraction data (including refined experimental phases) and experimentally confirmed sequences. BLAST comparisons of the SGX structures with structures that had appeared in the Protein Data Bank over the intervening 3.5 years since the SGX target list had been compiled identified homologs for 49 of the 60 unique sequences represented by the SGX structures. This result indicates that, for bacterial structures that are relatively easy to express, purify, and crystallize, the structural coverage of gene space is proceeding rapidly. More distant sequence-structure relationships between the SGX and PDB structures were investigated using PDB-BLAST and Combinatorial Extension (CE). Only one structure, SufD, has a truly unique topology compared to all folds in the PDB.

Requirement for the induced expression of a cell wall associated receptor kinase for survival during the pathogen response

Pathogen infection of angiosperms must rely on some interaction between the extracellular matrix (ECM) and the invading agent, and may be accompanied by signaling between the ECM and cytoplasm. An Arabidopsis cell wall associated receptor kinase (Wak1) has an amino-terminal domain that is tightly associated with the ECM, spans the plasma membrane and has a cytoplasmic protein kinase domain. Wak1 expression is induced when Arabidopsis plants are infected with pathogen, or when the pathogen response is stimulated either by exogenous salicylate (SA) or its analog 2,2-dichloroisonicotinic acid (INA). This Wak1 induction requires the positive regulator NPR1/NIM1. Thus Wak1 is a pathogen-related (PR) protein. Expression of an antisense and a dominant negative allele of Wak1 shows that induced expression of Wak1 is needed for a plant to survive if stimulated by INA. Ectopic expression of the entire Wak1, or the kinase domain alone, can provide resistance to otherwise lethal SA levels. These experiments suggest that Wak1 expression and other PR proteins are protecting plants from detrimental effects incurred during the pathogen response. These results provide a direct link between a protein kinase that could mediate signals from the ECM, to the events that are precipitated by a pathogen infection.

WAKs: cell wall-associated kinases linking the cytoplasm to the extracellular matrix

There are only a few proteins identified at the cell surface that could directly regulate plant cell wall functions. The cell wall-associated kinases (WAKs) of angiosperms physically link the plasma membrane to the carbohydrate matrix and are unique in that they have the potential to directly signal cellular events through their cytoplasmic kinase domain. In Arabidopsis there are five WAKs and each has a cytoplasmic serine/threonine protein kinase domain, spans the plasma membrane, and extends a domain into the cell wall. The WAK extracellular domain is variable among the five isoforms, and collectively the family is expressed in most vegetative tissues. WAK1 and WAK2 are the most ubiquitously and abundantly expressed of the five tandemly arrayed genes, and their messages are present in vegetative meristems, junctions of organ types, and areas of cell expansion. They are also induced by pathogen infection and wounding. Recent experiments demonstrate that antisense WAK expression leads to a reduction in WAK protein levels and the loss of cell expansion. A large amount of WAK is covalently linked to pectin, and most WAK that is bound to pectin is also phosphorylated. In addition, one WAK isoform binds to a secreted glycine-rich protein (GRP). The data support a model where WAK is bound to GRP as a phosphorylated kinase, and also binds to pectin. How WAKs are involved in signaling from the pectin extracellular matrix in coordination with GRPs will be key to our understanding of the cell wall's role in cell growth.

Porcine reproductive and respiratory syndrome virus productively infects monocyte-derived dendritic cells and compromises their antigen-presenting ability

Dendritic cells (DC) are potent antigen-presenting cells that play an important role in inducing primary antigen-specific immune responses. However, some viruses have evolved to specifically target DC to circumvent the host's immune responses for their persistence in the host. Porcine reproductive and respiratory syndrome virus (PRRSV) causes a persistent infection in susceptible animals. Although it is generally believed that the existence of PRRSV quasispecies is partly responsible for the virus persistence, other mechanisms of immune evasion or immune suppression may also exist. Here, we studied the role of DC in PRRSV persistence and immune suppression. Our results showed that PRRSV underwent a productive replication in pig monocyte-derived DC (Mo-DC) as measured by both immunofluorescence staining of viral nucleocapsid protein and virus titration assays, leading to cell death via both apoptosis and necrosis mechanisms. Additionally, PRRSV infection of Mo-DC resulted in reduced expression of MHC class I, MHC class II, CD14 and CD11b/c. This was in agreement with the impaired mixed lymphocyte reaction of PRRSV-infected Mo-DC compared to that of mock-infected Mo-DC. We also examined the cytokine profiles of PRRSV-infected Mo-DC using a quantitative ELISA method. Results indicated that no apparent change in the levels of IL-10, IL-12 and IFN-gamma was detected. Taken together, our data demonstrate that PRRSV productively infects Mo-DC and impairs the normal antigen presentation ability of Mo-DC by inducing cell death, down-regulating the expression of MHC class I, MHC class II, CD11b/c and CD14 and by inducing minimal Th1 cytokines.

A cluster of five cell wall-associated receptor kinase genes, Wak1-5, are expressed in specific organs of Arabidopsis

WAK1 (wall-associated kinase 1) is a cytoplasmic serine/threonine kinase that spans the plasma membrane and extends into the extracellular region to bind tightly to the cell wall. The Wak1 gene was mapped and found to lie in a tight cluster of five highly similar genes (Wak1-5) within a 30 kb region. All of the Wak genes encode a cytoplasmic serine/threonine protein kinase, a transmembrane domain, and an extracytoplasmic region with several epidermal growth factor (EGF) repeats. The extracellular regions also contain limited amino acid identities to the tenascin superfamily, collagen, or the neurexins. RNA blot analysis with gene-specific probes revealed that Wak1, Wak3 and Wak5 are expressed primarily in leaves and stems of Arabidopsis. Wak4 mRNA is only detected in siliques, while Wak2 mRNA is found in high levels in leaves and stems, and in lower levels in flowers and siliques. A trace amount of Wak2 can also be detected in roots. Wak1 is induced by pathogen infection and salicylic acid or its analogue INA and is involved in the plant's response, and Wak2, Wak3 and Wak5 also can be greatly induced by salicylic acid or INA. The WAK proteins have the potential to serve as both linkers of the cell wall to the plasma membrane and as signaling molecules, and since Wak expression is organ-specific and the isoforms vary significantly in the cell wall associated domain this family of proteins may be involved in cell wall-plasma membrane interactions that direct fundamental processes in angiosperms.

High doses of purified stem cells cause early hematopoietic recovery in syngeneic and allogeneic hosts

In humans, autologous transplants derived from bone marrow (BM) usually engraft more slowly than transplants derived from mobilized peripheral blood. Allogeneic BM transplants show a further delay in engraftment and have an apparent requirement for donor T cells to facilitate engraftment. In mice, Thy-1.1(lo)Lin-/loSca-1+ hematopoietic stem cells (HSCs) are the principal population in BM which is responsible for engraftment in syngeneic hosts at radioprotective doses, and higher doses of HSCs can radioprotect an allogeneic host in the absence of donor T cells. Using the mouse as a preclinical model, we wished to test to what extent engraftment kinetics was a function of HSC content, and whether at high doses of c-Kit+Thy-1.1(lo)Lin-/loSca-1+ (KTLS) cells rapid allogeneic engraftment could also be achieved. Here we demonstrate that engraftment kinetics varied greatly over the range of KTLS doses tested (100-10,000 cells), with the most rapid engraftment being obtained with a dose of 5,000 or more syngeneic cells. Mobilized splenic KTLS cells and the rhodamine 123(lo) subset of KTLS cells were also able to engraft rapidly. Higher doses of allogeneic cells were needed to produce equivalent engraftment kinetics. This suggests that in mice even fully allogeneic barriers can be traversed with high doses of HSCs, and that in humans it may be possible to obtain rapid engraftment in an allogeneic context with clinically achievable doses of purified HSCs.

Significance of heat-stable and heat-labile enterotoxins in porcine colibacillosis in an additive model for pathogenicity studies

Although heat-stable (ST) and heat-labile (LT) enterotoxins produced by enterotoxigenic Escherichia coli (ETEC) have been documented as important factors associated with diarrheal diseases, investigations assessing the contributions of individual enterotoxins to the pathogenesis of E. coli infection have been limited. To address the individual roles of enterotoxins in the diarrheal disease caused by K88-positive ETEC in young pigs, enterotoxin-positive and -negative isogenic E. coli strains were constructed by using pBR322 to clone and express LT and STb. Four strains, K88+ astA, K88+ astA/pBR322, K88+ astA STb+, and K88+ astA LT+, were constructed and subsequently included in gnotobiotic piglet challenge studies, and their pathogenesis was assessed. The results indicated that all K88+ isogenic strains were able to colonize the small intestines of piglets exhibiting the K88 receptor. However, only LT- and STb-positive strains caused appreciable diarrhea. Piglets inoculated with the K88+ astA LT+ strain became dehydrated within 18 h, while those inoculated with the K88+ astA STb+ strain did not, although diarrhea developed in several piglets. The changes in the blood packed-cell volume and plasma total protein of gnotobiotic piglets inoculated with the LT-positive strains were significantly greater than those of pigs inoculated with the K88 astA/pBR322 strain (P = 0.012, P = 0.002). Immunochemistry image analysis also suggested that LT enhanced bacterial colonization in a gnotobiotic piglet model. This investigation suggested that LT is a major contributor to the virulence of K88+ ETEC and that isogenic constructs are a useful tool for studying the pathogenesis of ETEC infection.

Multicenter randomized clinical trial of donepezil for memory impairment in multiple sclerosis

OBJECTIVES

The goal of this study was to determine if memory would be improved by donepezil as compared to placebo in a multicenter, double-blind, randomized clinical trial (RCT).

METHODS

Donepezil 10 mg daily was compared to placebo to treat memory impairment. Eligibility criteria included the following: age 18-59 years, clinically definite multiple sclerosis (MS), and performance ≤ ½ SD below published norms on the Rey Auditory Verbal Learning Test (RAVLT). Neuropsychological assessments were performed at baseline and 24 weeks. Primary outcomes were change on the Selective Reminding Test (SRT) of verbal memory and the participant's impression of memory change. Secondary outcomes included changes on other neuropsychological tests and the evaluating clinician's impression of memory change.

RESULTS

A total of 120 participants were enrolled and randomized to either donepezil or placebo. No significant treatment effects were found between groups on either primary outcome of memory or any secondary cognitive outcomes. A trend was noted for the clinician's impression of memory change in favor of donepezil (37.7%) vs placebo (23.7%) (p = 0.097). No serious or unanticipated adverse events attributed to study medication developed.

CONCLUSIONS

Donepezil did not improve memory as compared to placebo on either of the primary outcomes in this study.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence which does not support the hypothesis that 10 mg of donepezil daily for 24 weeks is superior to placebo in improving cognition as measured by the SRT in people with MS whose baseline RAVLT score was 0.5 SD or more below average.

Clostridium difficile toxin A causes early damage to mitochondria in cultured cells

BACKGROUND & AIMS

The mechanism by which Clostridium difficile toxin A causes actin depolymerization and cell rounding involves toxin internalization and subsequent monoglucosylation of the Rho family of proteins. This study explored toxin internalization and effects on mitochondrial function before cell rounding.

METHODS

Chinese hamster ovary (CHO) cells were exposed to toxin A, and mitochondrial localization was assayed by confocal microscopy. Mitochondrial function was measured by adenosine triphosphate (ATP) concentration, mitochondrial permeability, and leakage of cytochrome c.

RESULTS

Confocal microscopy showed toxin A colocalization with the mitochondrial protein GRP 75 at 5 minutes after toxin exposure. Between 5 and 15 minutes, toxin A caused an 80% diminution in cellular ATP levels; cell rounding and Rho glucosylation commenced between 15 and 30 minutes. Toxin A also resulted in reduction of mitochondrial membrane potential and a 2-3-fold increase in reactive oxygen radicals. Preincubation of CHO cells with the antioxidants butylated hydroxyanisole or butylated hydroxytoluene blocked the toxin A-induced increase in oxygen radicals and diminished cell rounding. Western blot analysis of toxin A-exposed isolated mitochondria showed a direct effect of toxin A on leakage of cytochrome c.

CONCLUSIONS

The results show that extensive mitochondrial damage occurs within 15 minutes in CHO cells exposed to toxin A. Diminished ATP concentrations and increased oxygen radicals are likely to contribute to cytotoxicity from this bacterial toxin.

Transforming growth factor beta -inducible independent binding of SMAD to the Smad7 promoter

SMAD proteins can mediate transforming growth factor beta (TGF-beta)-inducible transcriptional responses. Whereas SMAD can recognize specific DNA sequences, it is usually recruited to a promoter through interaction with a DNA-binding partner. In an effort to search for TGF-beta-inducible genes, we used a subtractive screening method and identified human Smad7, which can antagonize TGF-beta signaling and is rapidly up-regulated by TGF-beta. In this report, we show that TGF-beta can stabilize Smad7 mRNA and activate Smad7 transcription. The Smad7 promoter is the first TGF-beta responsive promoter identified in vertebrates that contains the 8-bp palindromic SMAD-binding element (SBE), an optimal binding site previously identified by a PCR-based selection from random oligonucleotides by using recombinant Smad3 and Smad4. We demonstrate that on TGF-beta treatment, endogenous SMAD complex can bind to a Smad7 promoter DNA as short as 14 or 16 bp that contains the 8-bp SBE in gel mobility shift and supershift assays. Our studies provide strong evidence that SMAD proteins can bind to a natural TGF-beta responsive promoter independent of other sequencespecific transcription factors. We further show that, whereas recombinant Smad3 binds to the SBE, endogenous or even transfected Smad3 cannot bind to the SBE in the absence of Smad4. These findings have important implications in the identification of target genes of the TGF-beta/SMAD signaling pathways.

Enhanced M1/M2 macrophage ratio promotes orthodontic root resorption

Mechanical force-induced orthodontic root resorption is a major clinical challenge in orthodontic treatment. Macrophages play an important role in orthodontic root resorption, but the underlying mechanism remains unclear. In this study, we examined the mechanism by which the ratio of M1 to M2 macrophage polarization affects root resorption during orthodontic tooth movement. Root resorption occurred when nickel-titanium coil springs were applied on the upper first molars of rats for 3 to 14 d. Positively stained odontoclasts or osteoclasts with tartrate-resistant acid phosphatase were found in resorption areas. Meanwhile, M1-like macrophages positive for CD68 and inducible nitric oxide synthase (iNOS) persistently accumulated on the compression side of periodontal tissues. In addition, the expressions of the M1 activator interferon-γ and the M1-associated pro-inflammatory cytokine tumor necrosis factor (TNF)-α were upregulated on the compression side of periodontal tissues. When the coil springs were removed at the 14th day after orthodontic force application, root resorption was partially rescued. The number of CD68(+)CD163(+) M2-like macrophages gradually increased on the compression side of periodontal tissues. The levels of M2 activator interleukin (IL)-4 and the M2-associated anti-inflammatory cytokine IL-10 also increased. Systemic injection of the TNF-α inhibitor etanercept or IL-4 attenuated the severity of root resorption and decreased the ratio of M1 to M2 macrophages. These data imply that the balance between M1 and M2 macrophages affects orthodontic root resorption. Root resorption was aggravated by an enhanced M1/M2 ratio but was partially rescued by a reduced M1/M2 ratio.

Localization of NuMA protein isoforms in the nuclear matrix of mammalian cells

Using a monoclonal antibody 2D3 generated against a kinetochore-enriched human chromosome preparation, we identified a high molecular mass protein with nuclear staining in interphase and polar staining of the pericentriolar region in the mitotic spindle. Initially termed centrophilin, this protein associates with the minus-ends of spindle microtubules (MT) and appears to be important in spindle organization [Tousson et al., 1991: J. Cell Biol. 112:427-440]. Comparison of a partial cDNA sequence obtained for centrophilin with the full length cDNA sequence of nuclear mitotic apparatus protein (NuMA) [Compton et al., 1992: J. Cell Biol. 116:1395-1408; Yang et al., 1992: J. Cell Biol. 116:1303-1317] has indicated that NuMA and centrophilin are the same protein. Using a polyclonal NuMA antibody, we have provided further evidence that NuMA exists as isoforms as shown by peptide mapping and immunoblots. Sequential fractionation experiments along with immunofluorescence, immunoblotting, and EM immunogold labeling have demonstrated that NuMA isoforms are novel components of nuclear core filaments. Thus, NuMA, a long coiled-coil protein, appears to have dual functions in interphase and mitosis during the cell cycle. In interphase, NuMA likely plays a structural role in the nucleoskeleton that may be important in nuclear organization and functions, whereas in mitosis, NuMA appears to be associated with spindle MT organization and chromosome positioning.

M1-like Macrophage Polarization Promotes Orthodontic Tooth Movement

Macrophages play a crucial role in inflammatory-mediated bone loss. Orthodontic tooth movement (OTM) is associated with inflammatory bone remodeling. However, whether and how macrophages contribute to mechanical force-induced OTM remains unknown. In this study, we hypothesized that polarization of M1-like macrophages may contribute to the OTM. Orthodontic nickel-titanium springs were applied to the upper first molars of rats or mice to induce OTM. The distance of OTM gradually increased after mechanical force was applied to the rats for 5 and 10 d. M1-like macrophage polarization and expression of M1 cytokine tumor necrosis factor (TNF)-α also increased after force application. More importantly, monocyte/macrophage depletion in mice by injection of clodronate liposomes decreased the distance of OTM and the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts and CD68(+) macrophages, accompanied by reduced expressions of M1 markers TNF-α and inducible nitric oxide synthase (iNOS), whereas systemic transfusion of M1 macrophages in mice increased them. Further experiments showed that injection of recombinant TNF-α increased the distance of OTM and the number of TRAP-positive osteoclasts and CD68(+) macrophages, as well as upregulated the expression of TNF-α and iNOS. Blockage of TNF-α by etanercept injection reduced the distance of OTM and the number of TRAP-positive osteoclasts and CD68(+) macrophages, as well as decreased the levels of TNF-α and iNOS. These data suggest that M1-like macrophage polarization promotes alveolar bone resorption and consequent OTM after mechanical force application.

Nuclear-mitotic apparatus protein: a structural protein interface between the nucleoskeleton and RNA splicing

Vertebrate splicing factors are localized to discrete domains within the nuclei of somatic cells. The mechanism whereby such nuclear domains, identified as speckles by immunofluorescence microscopy, are generated is unclear. Recent studies suggest that the spatial order within the nucleus is maintained by nuclear matrix factors. Here we show that a protein in the nuclear matrix and mitotic apparatus [nuclear-mitotic apparatus protein, NuMA; Lydersen, B. & Pettijohn, D. (1980) Cell 22, 489-499] colocalizes with splicing factors in interphase nuclei and is associated with small nuclear ribonucleoproteins in a complex immunoprecipitated from HeLa extract with small nuclear ribonucleoprotein antibodies. Moreover, NuMA associates with splicing complexes that are reconstituted in vitro using wild-type pre-mRNA, but not with nonspecific RNA. Cumulatively, these observations suggest a function of NuMA or NuMA-like proteins in interphase cells in providing a bridge between RNA processing and the nucleoskeleton.

Recombinant swine beta interferon protects swine alveolar macrophages and MARC-145 cells from infection with Porcine reproductive and respiratory syndrome virus

Swine beta interferon (swIFN-beta) produced in HEK 293 cells infected with a recombinant, replication-defective human adenovirus 5 (Ad5) encoding the swIFN-beta gene was tested for antiviral activity against Porcine reproductive and respiratory syndrome virus (PRRSV). MARC-145 cells were incubated overnight with dilutions of supernatant fluids from HEK 293 cells infected with Ad5-swIFN-beta or with an Ad5 control virus (Ad5-Blue). Treated cells were infected with PRRSV; MARC-145 cells incubated with Ad5-Blue supernatants developed cytopathic effects (CPE), whereas those incubated with swIFN-beta showed no CPE. To confirm the antiviral activity of swIFN-beta, culture fluids from Ad5-swIFN-beta-infected cells were affinity-purified on a Sepharose-anti-swIFN-beta matrix, and the resulting fractions exhibited antiviral activity upon infection with PRRSV. The antiviral effects were specific, as they were blocked by mAbs against swIFN-beta. Additional cultures of MARC-145 cells treated with swIFN-beta-containing supernatants or affinity-purified swIFN-beta were infected with PRRSV and tested by real-time RT-PCR for viral RNA in culture supernatants at various times post-inoculation. These experiments confirmed the protective effects of swIFN-beta. swIFN-beta was also tested for antiviral activity on porcine alveolar macrophages (PAMs) obtained by bronchoalveolar lavage from PRRSV-negative swine. PAMs were treated with dilutions of swIFN-beta or Ad5-Blue culture fluids, infected with PRRSV and tested for viral RNA by real-time RT-PCR. The viral load data showed a dose-dependent protection in swIFN-beta-treated PAMs, whereas no protection was evident from Ad5-Blue culture fluids. The data demonstrate that swIFN-beta protects both MARC-145 cells and PAMs from PRRSV infection.

Expression of a p53 mutant in the epidermis of transgenic mice accelerates chemical carcinogenesis

To develop an in vivo model for studying the role of the p53 tumor suppressor in skin carcinogenesis, a murine p53(172H) mutant (equivalent to human p53(175H)) was expressed in the epidermis of transgenic mice, utilizing a targeting vector based on the human keratin 1 gene (HK1.p53m). HK1.p53m mice developed normally and did not exhibit an obvious epidermal phenotype or develop spontaneous tumors. However, these mice demonstrated an increased susceptibility to a two-stage chemical carcinogenesis protocol, with the rate of formation and number of papillomas being dramatically increased as compared to non-transgenic controls. The majority of papillomas in control mice regressed after termination of 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment, whereas p53m papillomas progressed to carcinomas and metastases. In addition, more advanced malignancy, i.e., undifferentiated spindle cell carcinomas, were exclusively observed in p53m mice. Increased bromodeoxyuridine (BrdU) labeling, accompanied by decreased expression of p21, was observed in HK1.p53m papillomas. In situ examination of centrosomes in HK1.p53m papillomas also revealed marked abnormalities, with 75% of the cells containing > or = 3 centrosomes/cell, whereas centrosome numbers in papillomas from control animals remained normal. These data suggest that the accelerated tumorigenesis observed in chemically-treated p53m mice is most likely due to increased genomic instability resulting from an inhibition of G1 arrest and abnormal amplification of centrosomes.

Human cytosolic sulfotransferase 2B1: isoform expression, tissue specificity and subcellular localization

Sulfation is an important Phase II conjugation reaction involved in the synthesis and metabolism of steroids in humans. Two different isoforms (2B1a and 2B1b) are encoded by the sulfotransferase (SULT) 2B1 gene utilizing different start sites of transcription resulting in the incorporation of different first exons. SULT2B1a and SULT2B1b are 350 and 365 amino acids in length, respectively, and the last 342 aa are identical. Message for both SULT2B1 isoforms is present in human tissues although SULT2B1b message is generally more abundant. However, to date only SULT2B1b protein has been detected in human tissues or cell lines. SULT2B1b is localized in the cytosol and/or nuclei of human cells. A unique 3'-extension of SULT2B1b is required for nuclear localization in human BeWo placental choriocarcinoma cells. Nuclear localization is stimulated by forskolin treatment in BeWo cells and serine phosphorylation has been identified in the 3'-extension. SULT2B1b is selective for the sulfation of 3beta-hydroxysteroids such as dehydroepiandrosterone and pregnenolone, and may also have a role in cholesterol sulfation in human skin. The substrate specificity, nuclear localization, and tissue localization of SULT2B1b suggest a role in regulating the responsiveness of cells to adrenal androgens via their direct inactivation or by preventing their conversion to more potent androgens and estrogens.

Inducible nitric oxide synthase expression is selectively induced in astrocytes isolated from adult human brain

Inducible nitric oxide synthase (iNOS) expression has been shown to be differentially regulated among different cell types and species. In cultures of primary human fetal glial cells, we have shown that astrocytes rather than microglia express iNOS. In the present study, we extended these findings to primary cultures of astrocytes and microglia derived from adult human brains. Mixed cultures of adult brain tissue were stimulated with IL-1beta and IFNgamma, a combination known to induce iNOS maximally in human fetal cells, and the expression of iNOS was determined by immunocytochemistry. Cell types were determined by morphology as well as immunocytochemistry for GFAP (astrocytes) and CD68 (microglia). The results showed that in cultures of adult human glia, iNOS was expressed following stimulation with cytokines, and the expression was restricted to astrocytes. Astrocyte iNOS immunoreactivity was detected both in the cytosol and in a discrete paranuclear region, a pattern noted in human fetal astrocytes. These results demonstrate that the ability to express iNOS is common to both fetal and adult human astrocytes.

CHIP/Stub1 regulates the Warburg effect by promoting degradation of PKM2 in ovarian carcinoma

Tumor cells preferentially adopt aerobic glycolysis for their energy supply, a phenomenon known as the Warburg effect. It remains a matter of debate as to how the Warburg effect is regulated during tumor progression. Here, we show that CHIP (carboxyl terminus of Hsc70-interacting protein), a U-box E3 ligase, suppresses tumor progression in ovarian carcinomas by inhibiting aerobic glycolysis. While CHIP is downregulated in ovarian carcinoma, induced expression of CHIP results in significant inhibition of the tumor growth examined by in vitro and in vivo experiments. Reciprocally, depletion of CHIP leads to promotion of tumor growth. By a SiLAD proteomics analysis, we identified pyruvate kinase isoenzyme M2 (PKM2), a critical regulator of glycolysis in tumors, as a target that CHIP mediated for degradation. Accordingly, we show that CHIP regulates PKM2 protein stability and thereafter the energy metabolic processes. Depletion or knockout of CHIP increased the glycolytic products in both tumor and mouse embryonic fibroblast cells. Simultaneously, we observed that CHIP expression inversely correlated with PKM2 levels in human ovarian carcinomas. This study reveals a mechanism that the Warburg effect is regulated by CHIP through its function as an E3 ligase, which mediates the degradation of PKM2 during tumor progression. Our findings shed new light into understanding of ovarian carcinomas and may provide a new therapeutic strategy for ovarian cancer.

Comparison of a paraspinal approach with a percutaneous approach in the treatment of thoracolumbar burst fractures with posterior ligamentous complex injury: a prospective randomized controlled trial

OBJECTIVE

This prospective randomized controlled study compared the efficacy and safety of two paraspinal muscle-sparing surgical approaches for the management of neurologically intact patients with thoracolumbar burst fractures and posterior ligamentous complex injuries.

METHODS

Patients were randomized to undergo either percutaneous (n=31) or paraspinal (n=30) fluoroscopically-guided pedicle screw-rod fixation, and were followed for ≥3 years. Preoperative postural reduction was attempted in all patients.

RESULTS

The percutaneous approach was associated with significantly less intraoperative blood loss and shorter duration of surgery and hospitalization, as well as less pain and better functional recovery at 3 months after surgery compared with the paraspinal approach. Paraspinal surgery resulted in significantly better correction of kyphosis and restoration of vertebral height compared with percutaneous surgery. There were no differences in long-term clinical outcomes between the two groups.

CONCLUSIONS

The minimally invasive percutaneous approach appears to be better in cases of successful postural reduction. The paraspinal approach results in better surgical correction and is, therefore, recommended for patients without successful postural reduction.

The C terminus of mitosin is essential for its nuclear localization, centromere/kinetochore targeting, and dimerization

Mitosin is a novel 350-kDa nuclear phosphoprotein that dramatically relocates from the evenly nuclear distribution in S phase to the centromere/kinetochore and mitotic apparatus in M phase. The dynamic relocalization of mitosin is accompanied by the phosphorylation of itself, suggesting that mitosin plays a role in mitotic progression. The molecular basis of nuclear localization and targeting of mitosin to the centromere/kinetochore were characterized using a set of epitope-tagged deletion mutants. The data indicate that the extreme C terminus (amino acids 2,487-3,113) of mitosin has both an independent centromere/kinetochore targeting domain and an unusually spaced bipartite nuclear localization signal. Moreover, the same centromere/kinetochore targeting domain was shown to be essential for the ability of mitosin to bind to itself or other putative mitosin-associated proteins through use of the yeast two-hybrid system. These results suggest that the C terminus of the mitosin is essential for its role in influencing cell cycle progression.