Increased Lysis of Stem Cells but Not Their Differentiated Cells by Natural Killer Cells; De-Differentiation or Reprogramming Activates NK Cells

The aims of this study are to demonstrate the increased lysis of stem cells but not their differentiated counterparts by the NK cells and to determine whether disturbance in cell differentiation is a cause for increased sensitivity to NK cell mediated cytotoxicity. Increased cytotoxicity and augmented secretion of IFN-γ were both observed when PBMCs or NK cells were co-incubated with primary UCLA oral squamous carcinoma stem cells (UCLA-OSCSCs) when compared to differentiated UCLA oral squamous carcinoma cells (UCLA-OSCCs). In addition, human embryonic stem cells (hESCs) were also lysed greatly by the NK cells. Moreover, NK cells were found to lyse human Mesenchymal Stem Cells (hMSCs), human dental pulp stem cells (hDPSCs) and human induced pluripotent stem cells (hiPSCs) significantly more than their differentiated counterparts or parental lines from which they were derived. It was also found that inhibition of differentiation or reversion of cells to a less-differentiated phenotype by blocking NFκB or targeted knock down of COX2 in monocytes significantly augmented NK cell cytotoxicity and secretion of IFN-γ. Taken together, these results suggest that stem cells are significant targets of the NK cell cytotoxicity. However, to support differentiation of a subset of tumor or healthy untransformed primary stem cells, NK cells may be required to lyse a number of stem cells and/or those which are either defective or incapable of full differentiation in order to lose their cytotoxic function and gain the ability to secrete cytokines (split anergy). Therefore, patients with cancer may benefit from repeated allogeneic NK cell transplantation for specific elimination of cancer stem cells.     

Relationship between quiet standing position and perceptibility of standing position in the anteroposterior direction

We investigated the relationship between an individual's center of pressure in the anteroposterior direction in quiet standing (QS) and perceptibility of different standing positions. The position of the center of pressure in the anteroposterior direction (CoPy position) while standing was represented as the percentage distance (%FL) from the hindmost point of the heel in relation to foot length. CoPy position in QS was located from 31 to 58%FL. Perceptibility of standing position was evaluated by the difference between the reference position and the subject's attempt to reproduce that position. Subjects were tested for their ability to reproduce reference positions selected randomly from a total of 13 positions at 5%FL increments from 20 to 80%FL. Using an approximation formula curve, we identified the relationship between reference position and reproduction absolute error. The standing position range with reproduction error exceeding 90% of the difference between the maximum and minimum errors was defined as the low perceptibility range of standing position. The approximation curve had one peak near QS. CoPy positions in QS were located in the low perceptibility range, except for five subjects with a more posterior location. The correlation coefficient between CoPy positions in QS (x) and reference position (y) showing maximum error was 0.70 and the regression line was y=0.464x+28.2; the intersection point with y=x was 53%FL. Reproduction absolute errors in reference positions at 20-30%FL and 70-80%FL were significantly smaller than those at 40-60%FL (p<0.05). We concluded the following. (1) Standing positions showing the lowest perceptibility are located close to the QS position; however, in subjects whose QS position is located more posteriorly, the standing position showing maximum error is more anterior. (2) Perceptibility of extreme forward- and backward-leaning positions is very high and independent of individual QS position.     

Human immunodeficiency virus type 1 Vpr induces cell cycle arrest at the G(1) phase and apoptosis via disruption of mitochondrial function in rodent cells

Vpr of human immunodeficiency virus type 1 causes cell cycle arrest at the G(2)/M phase and induces apoptosis after G(2)/M arrest in primate cells. We have reported previously that Vpr also induces apoptosis independently of G(2)/M arrest in human HeLa cells. By contrast, Vpr does not induce G(2)/M arrest in rodent cells, but it retards cell growth. To clarify the relationship between cell cycle arrest and apoptosis, we expressed Vpr endogenously in rodent cells and investigated cell cycle profiles and apoptosis. We show here that Vpr induces cell cycle arrest at the G(1) phase and apoptosis in rodent cells. Vpr increased the activity of caspase-3 and caspase-9, but not of caspase-8. Moreover, Vpr-induced apoptosis could be inhibited by inhibitors of caspase-3 and caspase-9, but not by inhibitor of caspase-8. We also showed that Vpr induces the release of cytochrome c from mitochondria into the cytosol and disrupts the mitochondrial transmembrane potential. Finally, we showed that apoptosis occurred in HeLa cells through an identical pathway. These results suggest that disruption of mitochondrial functions by Vpr induces apoptosis via cell cycle arrest at G(1), but that apoptosis is independent of G(2)/M arrest. Furthermore, it appears that Vpr acts species-specifically with respect to induction of cell cycle arrest but not of apoptosis.     

Structural elucidation of a novel core oligosaccharide backbone of the lipopolysaccharide from the new bacterial species Agrobacterium larrymoorei

Agrobacterium larrymoorei is a Gram-negative phytopathogenic bacterium, which produces tumours on Ficus benjamina plants and differs from other Agrobacteria both genetically and biochemically. The lipopolysaccharide (LPS) plays an important role in the pathogenesis of Agrobacteria. The present paper is the first report on the molecular primary structure of the core region of an Agrobacterium LPS. The following structure of the core and lipid A carbohydrate backbone of an R-form LPS of A. larrymoorei was determined by chemical degradations and 1D and 2D NMR spectroscopy: [carbohydrate structure: see text] All sugars are alpha-D-pyranoses if not stated otherwise, Kdo is 3-deoxy-D-manno-oct-2-ulosonic acid, Qui3NAcyl is 3,6-dideoxy-3-(3-hydroxy-2,3-dimethyl-5-oxoprolylamino)glucose, GlcAN and GalAN are amides of GlcA and GalA.     

Attitudes of medical staff towards the psychiatric label "schizophrenic patient" tested by an anti-stigma questionnaire

The aim of this research was to investigate the opinions and attitudes of medical staff towards schizophrenic patients. The research included three groups of examinees, 200 physicians of various specialties, 200 nurses and technicians working in Zagreb city hospitals, and 200 3rd and 4th year students of the School of Medicine in Zagreb. Previously validated anti-stigma questionnaire was used, consisting of 25 questions divided into three thematic groups, structured and adapted to the specific requirements of this study. The results were mutually compared and statistically analyzed by applying the chi 2-test. Significant difference (p < 0.01) between the answers of physicians and those of medical students was found in questions 2, 4, 5, 6, 11, 13, 15, 16, 18, 22, 23, 25, and between physicians and nurses/technicians in answers to questions 4, 15, 22, 23. Significant difference (p < 0.01) between the answers given by nurses/technicians and medical students was found in questions 10, 13, 22, 23. The results point to the existence of prejudices and stigmatizing attitudes in all three investigated groups. The most frequent reasons for stigmatizing attitude of students are based on fear and insufficient knowledge about mental patients and schizophrenia as a disease, while there are a high percentage of positive answers to the questions on rehabilitation and resocialization. The nurses/technicians also show a high degree of mistrust towards schizophrenic patients and mostly answer with "I don't know", thus presenting insufficiently formed attitudes about the mentioned problems. The physicians in their answers confirm fear, mistrust and stigmatizing attitudes towards schizophrenic patients found in general population in Croatia. The consequences of such attitudes are the low quality of life of schizophrenic patients, and slow, often incomplete, resocialization.     

A mutant form of the tax protein of bovine leukemia virus (BLV), with enhanced transactivation activity,increases expression and propagation of BLV in vitro but not in vivo

In a previous study, we identified an interesting mutant form of the Tax protein of bovine leukemia virus (BLV), designated D247G. This mutant protein strongly transactivated the long terminal repeat of BLV and was also able to transactivate the cellular proto-oncogene c-fos. This finding suggested that BLV that encode the mutant protein might propagate and induce lymphoma more efficiently than wild-type BLV. To characterize the effects of the strong transactivation activity of the mutant Tax protein, we constructed an infectious molecular clone of BLV that encoded D247G and examined the replication and propagation of the virus in vitro and in vivo. Cultured cells were transfected with the wild-type and mutant BLV, and then levels of viral proteins and particles and the propagation of viruses were compared. As expected, in vitro, mutant BLV produced more viral proteins and particles and was transmitted very effectively. We injected the wild-type and mutant BLV into sheep, which are easily infected with BLV, and monitored the proportion of BLV-positive cells in the blood and the expression of BLV RNA for 28 weeks. By contrast to the results of our analyses in vitro, we found no significant difference in the viral load or the expression of viral RNA between sheep inoculated with wild-type or mutant BLV. Our observations indicate that the mutant D247G Tax protein does not enhance the expansion of BLV and that there might be a dominant mechanism for regulation of the expression of BLV in vivo.     

Latency of viral expression in vivo is not related to CpG methylation in the U3 region and part of the R region of the long terminal repeat of bovine leukemia virus

Bovine leukemia virus (BLV) is silent in most cells detectable in vivo, and the repression of its expression allows BLV to evade the host's immune response. In this study, we examined whether CpG methylation of DNA might be involved in the regulation of the expression of BLV in vivo. To investigate the effects of CpG methylation on the activity of the long terminal repeat (LTR) of BLV, we measured the transactivation activity of this region after treatment with the CpG methyltransferase SssI by using a luciferase reporter system. The activity of methylated LTR was significantly lower than that of nonmethylated LTR. Therefore, we examined the extent of CpG methylation of the U3 region and part of the R region of the LTR in BLV-infected cattle and in experimentally BLV-infected sheep at various clinical stages by the bisulfite genomic sequencing method. We detected no or minimal CpG methylation at all stages examined in cattle and sheep, and our results indicate that CpG methylation probably does not participate in the silencing of BLV in vivo.