Regeneration of hyaline cartilage by cell-mediated gene therapy using transforming growth factor beta 1-producing fibroblasts

Transforming growth factor beta (TGF-beta) has been considered as a candidate for gene therapy of orthopedic diseases. The possible application of cell-mediated TGF-beta gene therapy as a new treatment regimen for degenerative arthritis was investigated. In this study, fibroblasts expressing active TGF-beta 1 were injected into the knee joints of rabbits with artificially made cartilage defects to evaluate the feasibility of this therapy for orthopedic diseases. Two to 3 weeks after the injection there was evidence of cartilage regeneration, and at 4 to 6 weeks the cartilage defect was completely filled with newly grown hyaline cartilage. Histological analyses of the regenerated cartilage suggested that it was well integrated with the adjacent normal cartilage at the sides of the defect and that the newly formed tissue was indeed hyaline cartilage. Our findings suggest that cell-mediated TGF-beta 1 gene therapy may be a novel treatment for orthopedic diseases in which hyaline cartilage damage has occurred.

Effect of radiation therapy on thoracic and lumbar bone marrow: evaluation with MR imaging

Bone marrow suppression is often the limiting factor in the use of radiation therapy. In order to determine if MR imaging can be used to quantify bone marrow changes, we performed a serial prospective study of patients with lung cancer (six cases) and lymphoma (six cases). Quantitative and qualitative assessments of T1-weighted sagittal images, 750/33 (TR/TE), obtained at 0.6 T before, during, and after radiotherapy showed increased signal intensity in the radiated portions of the spine. These changes appeared as early as 2 weeks after the beginning of radiation, continued to increase until a maximum value was attained, and then persisted during the follow-up period of 2 years. A significantly higher (p less than .04) ratio of pretreatment to maximum posttreatment signal intensity was seen in patients with lymphoma than in those with lung cancer, and pretreatment values in patients with lymphoma were significantly lower (p less than .01). The lower pretreatment values found in the patients with lymphoma may have been due to the smaller amount of yellow marrow in these patients, who were significantly younger (33 vs 62 years). The higher ratio of pre- and posttreatment signal intensity may have been related to the larger amount of hematopoietic marrow available to undergo fatty replacement. The persistence of elevated signal intensity for as long as 2 years after radiation suggests an endpoint in the process of marrow conversion, but not reversal in the form of regeneration of hematopoietic bone marrow. Quantitative MR evaluation of bone marrow may be of considerable value as a noninvasive means of monitoring the effects of radiotherapy.

Substance P antagonist (CP-96,345) inhibits HIV-1 replication in human mononuclear phagocytes

Substance P (SP) is a potent modulator of neuroimmunoregulation. We recently reported that human immune cells express SP and its receptor. We have now investigated the possible role that SP and its receptor plays in HIV infection of human mononuclear phagocytes. SP enhanced HIV replication in human blood-isolated mononuclear phagocytes, whereas the nonpeptide SP antagonist (CP-96,345) potently inhibited HIV infectivity of these cells in a concentration-dependent fashion. CP-96,345 prevented the formation of typical giant syncytia induced by HIV Bal strain replication in these cells. This inhibitory effect of CP-96,345 was because of the antagonism of neurokinin-1 receptor, a primary SP receptor. Both CP-96,345 and anti-SP antibody inhibited SP-enhanced HIV replication in monocyte-derived macrophages (MDM). Among HIV strains tested (both prototype and primary isolates), only the R5 strains (Bal, ADA, BL-6, and CSF-6) that use the CCR5 coreceptor for entry into MDM were significantly inhibited by CP-96,345; in contrast, the X4 strain (UG024), which uses CXCR4 as its coreceptor, was not inhibited. In addition, the M-tropic ADA (CCR5-dependent)-pseudotyped HIV infection of MDM was markedly inhibited by CP-96,345, whereas murine leukemia virus-pseudotyped HIV was not affected, indicating that the major effect of CP-96,345 is regulated by Env-determined early events in HIV infection of MDM. CP-96,345 significantly down-regulated CCR5 expression in MDM at both protein and mRNA levels. Thus, SP-neurokinin-1 receptor interaction may play an important role in the regulation of CCR5 expression in MDM, affecting the R5 HIV strain infection of MDM.

Utility elicitation study in the UK general public for late-stage chronic lymphocytic leukaemia

OBJECTIVES

In the United Kingdom (UK), chronic lymphocytic leukaemia (CLL) makes up 40 % of all leukaemias in patients over 65 years. The study objective was to obtain societal preferences in the UK for "progression-free" and "progressive" states of late-stage CLL, refractory to current first and second line regimens. Preferences were also obtained for selected treatment-related adverse events (AEs).

METHODS

A utility elicitation study, using the time trade-off (TTO) method, was conducted by face-to-face interviews with 110 subjects for a baseline disease state (before treatment), three primary disease states [progression-free survival (PFS) and treatment responder, PFS and treatment non-responder and disease progression], and 4 AE sub-states (PFS responder with thrombocytopenia, neutropenia, and infection, and PFS non-responder with infection). TTO scores were converted into utility values, and disutilities were calculated for AEs. Visual analogue scale (VAS) scores were obtained.

RESULTS

The primary disease state mean TTO utility scores were: baseline: 0.549; PFS response: 0.671; PFS non-response: 0.394; and progression: 0.214. The mean TTO utility (disutility) scores for the AEs were: PFS response with thrombocytopenia, 0.563 (-0.108), neutropenia, 0.508 (-0.163), and infection, 0.476 (-0.195); PFS non-response with infection, 0.333 (-0.061). The VAS results were in line with the TTO results.

CONCLUSIONS

The utility was higher for the PFS state than baseline, but decreased below baseline in non-response and disease progression states. AEs had an impact on utility within the PFS response state. The severe infection AE had a greater impact on utilities for the responding to treatment state compared to the non-responder state.

Continuous B-cell epitopes in Chlamydia trachomatis heat shock protein 60

B-cell peptide epitopes in chlamydial heat shock protein 60 (hsp60) were elucidated with antisera from 13 rabbits immunized with Chlamydia trachomatis serovars B, C, and L2 and antisera from eight women with C. trachomatis-associated ectopic pregnancies. Thirteen major epitopes were identified with the human sera, 10 of which were also observed with rabbit antisera. Seven of the 13 epitopes recognized by human antisera exhibited cross-reactive antibody binding to homologous peptide sequences in human hsp60. Self-reactive B-cell immunity to hsp60 may contribute to chlamydial disease pathogenesis.

Autoimmunity to heat shock protein 60 and antigen-specific production of interleukin-10

The immunopathologic sequelae of chlamydial infection are correlated with immune responses to the Chlamydia trachomatis heat shock protein 60 (hsp60). One pathogenic mechanism that may explain this association is the induction of autoimmune responses to self hsp60, since these two proteins share a high degree of amino acid sequence identity. To investigate the conditions under which autoimmune responses can be generated against self hsp60, groups of CBA mice were immunized with recombinant mouse hsp60, recombinant chlamydial hsp60, or both proteins. The data show that autoimmune responses characterized by strong T-cell proliferation and high titers of antibody to self hsp60 are induced only by concurrent immunization with mouse and chlamydial hsp60. Immunization with mouse hsp60 alone induced lymphocytes that secreted high levels of interleukin-10 (IL-10) but did not proliferate in response to in vitro stimulation with mouse hsp60; coimmunization with mouse and chlamydial hsp60s induced lymphocytes that proliferated strongly in response to mouse hsp60, secreted 6-fold less IL-10, and exhibited a 12-fold increase in the ratio of gamma interferon/IL-10 production. Switches in cytokine production patterns may mediate the pathogenesis of hsp60-associated diseases such as C. trachomatis immunopathology.

MR imaging of pleural effusions

To investigate the in vivo magnetic resonance (MR) characteristics of pleural effusions, MR imaging was performed on 22 patients who also underwent thoracentesis. Correlation of the MR scans with results of thoracentesis revealed significant differences among three types of effusions: transudates (T) (n = 4), simple exudates (SE) (n = 9), which did not have malignant cells or infection, and complex exudates (CE) (n = 9), which did have malignant cells or infection. Using normalized MR intensities, CE were more intense than SE, which were brighter than T. The second and third echoes (TE 66 and 99 ms) provided the best differentiation for these three classes of effusions, with p less than 0.06 and p less than 0.006, respectively. Qualitative visual assessment of the increase in signal intensity was also useful in differentiating among the three types of effusions (p less than 0.02). Effective T2 values (normalized to fat) were significantly shorter for exudates than for T (p less than 0.02). Heterogeneity, loculation, and size of effusions were well evaluated on MR. Magnetic resonance is not specific for the etiology of effusions. Nevertheless, with analysis of both quantitative and qualitative parameters, MR may provide an effective noninvasive means for the initial characterization and serial follow-up of pleural effusions.

Disruption of PPARgamma signaling results in mouse prostatic intraepithelial neoplasia involving active autophagy

Peroxisome proliferator-activated receptor-gamma (PPARgamma) regulates the interface between cellular lipid metabolism, redox status and organelle differentiation. Conditional prostatic epithelial knockout of PPARgamma in mice resulted in focal hyperplasia which developed into mouse prostatic intraepithelial neoplasia (mPIN). The grade of PIN became more severe with time. Electron microscopy (EM) showed accumulated secondary lysosomes containing cellular organelles and debris suggestive of autophagy. Consistent with this analysis the autophagy marker LC-3 was found to be upregulated in areas of PIN in PPARgamma KO tissues. We selectively knocked down PPARgamma2 isoform in wild-type mouse prostatic epithelial cells and examined the consequences of this in a tissue recombination model. Histopathologically grafted tissues resembled the conditional PPARgamma KO mouse prostates. EM studies of PPARgamma- and PPARgamma2-deficient epithelial cells in vitro were suggestive of autophagy, consistent with the prostatic tissue analysis. This was confirmed by examining expression of beclin-1 and LC-3. Gene expression profiling in PPARgamma-/gamma2-deficient cells indicated a major dysregulation of cell cycle control and metabolic signaling networks related to peroxisomal and lysosomal maturation, lipid oxidation and degradation. The putative autophagic phenotypes of PPARgamma-deficient cells could be rescued by re-expression of either gamma1 or gamma2 isoform. We conclude that disruption of PPARgamma signaling results in autophagy and oxidative stress during mPIN pathogenesis.

Over-expression of ERT(ESX/ESE-1/ELF3), an ets-related transcription factor, induces endogenous TGF-beta type II receptor expression and restores the TGF-beta signaling pathway in Hs578t human breast cancer cells

The epithelium-specific transcription factor, ERT/ESX/ESE-1/ELF3, binds to the TGF-beta RII promoter in a sequence specific manner and regulates its expression. In this study, we investigated whether ERT could regulate endogenous TGF-beta RII expression in Hs578t breast cancer cells. Analyses of the Hs578t parental cell line revealed low RII mRNA expression and resistance to the growth inhibitory effects of TGF-beta. Infection of this cell line with a retroviral construct expressing ERT induced higher levels of endogenous RII mRNA expression and protein expression relative to cells infected with chloramphenicol acetyltransferase (CATneo) as a control. Relative to control cells, the ERTneo-expressing Hs578t cells show approximately a 50% reduction in cell growth in the presence of exogenous TGF-beta1, as well as a fourfold higher induction of activation in transient transfection assays using the 3TP-luciferase reporter construct. When transplanted into athymic mice, ERT-expressing Hs578t cells showed decreased and delayed tumorigenicity compared with control cells. This data strongly suggests that ERT plays an important role as a transcriptional activator of TGF-beta RII expression, and that deregulated ERT expression may play a critical role in rendering Hs578t human breast cancer cells insensitive to TGF-beta's growth inhibitory effects.

PPARγ isoforms differentially regulate metabolic networks to mediate mouse prostatic epithelial differentiation

Recent observations indicate prostatic diseases are comorbidities of systemic metabolic dysfunction. These discoveries revealed fundamental questions regarding the nature of prostate metabolism. We previously showed that prostate-specific ablation of PPARγ in mice resulted in tumorigenesis and active autophagy. Here, we demonstrate control of overlapping and distinct aspects of prostate epithelial metabolism by ectopic expression of individual PPARγ isoforms in PPARγ knockout prostate epithelial cells. Expression and activation of either PPARγ 1 or 2 reduced de novo lipogenesis and oxidative stress and mediated a switch from glucose to fatty acid oxidation through regulation of genes including Pdk4, Fabp4, Lpl, Acot1 and Cd36. Differential effects of PPARγ isoforms included decreased basal cell differentiation, Scd1 expression and triglyceride fatty acid desaturation and increased tumorigenicity by PPARγ1. In contrast, PPARγ2 expression significantly increased basal cell differentiation, Scd1 expression and AR expression and responsiveness. Finally, in confirmation of in vitro data, a PPARγ agonist versus high-fat diet (HFD) regimen in vivo confirmed that PPARγ agonization increased prostatic differentiation markers, whereas HFD downregulated PPARγ-regulated genes and decreased prostate differentiation. These data provide a rationale for pursuing a fundamental metabolic understanding of changes to glucose and fatty acid metabolism in benign and malignant prostatic diseases associated with systemic metabolic stress.

Effects of topical corticosteroids on inflammatory mediator-induced eicosanoid release by human airway epithelial cells

BACKGROUND

Airway epithelial cells are among the first cells to come in contact with aerosolized corticosteroids. However, the relative potencies and time course of action of the several commonly used aerosolized corticosteroids on eicosanoid production by airway epithelial cells are unknown.

OBJECTIVES

This study compared the effects of fluticasone, budesonide, and triamcinolone on eicosanoid output by human airway epithelial cells in vitro. We also determined the spectrum of eicosanoids affected and the mechanism for corticosteroid action.

METHODS

Cultured BEAS-2B airway epithelial cells (a transformed cell line) were exposed to corticosteroids (1 nmol/L to 1 micromol/L) for 2 to 48 hours and then assayed for basal- and bradykinin (BK)-stimulated eicosanoid output. The eicosanoid profile was identified by HPLC in tritiated arachidonic acid prelabelled cells, and PGE2, the major eicosanoid product, was quantitated by RIA. The effect of corticosteroids on the immunoreactivity of key proteins involved in eicosanoid metabolism (ie, cyclooxygenase [COX], phospholipase A2 [PLA2], and Clara cell protein, a PLA2 inhibitor) was determined by Western blotting.

RESULTS

Eicosanoid output was largely confined to prostaglandins with values of 5 +/- 2 and 82 +/- 35 ng PGE2/10(6) cells for basal- and BK stimulation, respectively (n = 8). All 3 corticosteroids inhibited basal- and BK-induced PGE2 output in a dose- and time-dependent manner. Fluticasone and budesonide completely eliminated PGE2 output in nanomolar concentrations in contrast to triamcinolone, which required micromolar concentration. The rank order of potency was: fluticasone = budesonide > triamcinolone. The time course of action for PGE2 inhibition also differed, with budesonide acting more slowly than the other 2 corticosteroids (P = .04). All 3 corticosteroids markedly reduced COX2 with little effect on COX1, cPLA2 (Type IV), or iPLA2 (Type VI) immunoreactivity or their relative distribution in cytosol versus membrane fractions. Clara cell protein immunoreactivity was undetectable in control and corticosteroid-treated cell lysates.

CONCLUSION

These results show that in a human airway epithelial cell line, the 3 inhaled corticosteroids commonly used to treat asthma differ in onsets of action as inhibitors of prostaglandin synthesis and vary considerably in potency. All 3 corticosteroids act mechanistically in similar fashion by inhibiting COX2 synthesis.

Tissue Clearing and Its Application to Bone and Dental Tissues

Opaqueness of animal tissue can be attributed mostly to light absorption and light scattering. In most noncleared tissue samples, confocal images can be acquired at no more than a 100-µm depth. Tissue-clearing techniques have emerged in recent years in the neuroscience field. Many tissue-clearing methods have been developed, and they all follow similar working principles. During the tissue-clearing process, chemical or physical treatments are applied to remove components blocking or scattering the light. Finally, samples are immersed in a designated clearing medium to achieve a uniform refractive index and to gain transparency. Once the transparency is reached, images can be acquired even at several millimeters of depth with high resolution. Tissue clearing has become an essential tool for neuroscientists to investigate the neural connectome or to analyze spatial information of various types of brain cells. Other than neural science research, tissue-clearing techniques also have applications for bone research. Several methods have been developed for clearing bones. Clearing treatment enables 3-dimensional imaging of bones without sectioning and provides important new insights that are difficult or impossible to acquire with conventional approaches. Application of tissue-clearing technique on dental research remains limited. This review will provide an overview of the recent literature related to the methods and application of various tissue-clearing methods. The following aspects will be covered: general principles for the tissue-clearing technique, current available methods for clearing bones and teeth, general principles of 3-dimensional imaging acquisition and data processing, applications of tissue clearing on studying biological processes within bones and teeth, and future directions for 3-dimensional imaging.

DNA copy number aberrations in small-cell lung cancer reveal activation of the focal adhesion pathway

Small-cell lung cancer (SCLC) is the most aggressive subtype of lung cancer in its clinical behavior, with a 5-year overall survival as low as 5%. Despite years of research in the field, molecular determinants of SCLC behavior are still poorly understood, and this deficiency has translated into an absence of specific diagnostics and targeted therapeutics. We hypothesized that tumor DNA copy number alterations would allow the identification of molecular pathways involved in SCLC progression. Array comparative genomic hybridization was performed on DNA extracted from 46 formalin-fixed paraffin-embedded SCLC tissue specimens. Genomic profiling of tumor and sex-matched control DNA allowed the identification of 70 regions of copy number gain and 55 regions of copy number loss. Using molecular pathway analysis, we found a strong enrichment in these regions of copy number alterations for 11 genes associated with the focal adhesion pathway. We verified these findings at the genomic, gene expression and protein level. Focal Adhesion Kinase (FAK), one of the central genes represented in this pathway, was commonly expressed in SCLC tumors and constitutively phosphorylated in SCLC cell lines. Those were poorly adherent to most substrates but not to laminin-322. Inhibition of FAK phosphorylation at Tyr(397) by a small-molecule inhibitor, PF-573,228, induced a dose-dependent decrease of adhesion and an increase of spreading in SCLC cell lines on laminin-322. Cells that tended to spread also showed a decrease in focal adhesions, as demonstrated by a decreased vinculin expression. These results support the concept that pathway analysis of genes in regions of copy number alterations may uncover molecular mechanisms of disease progression and demonstrate a new role of FAK and associated adhesion pathways in SCLC. Further investigations of FAK at the functional level may lead to a better understanding of SCLC progression and may have therapeutic implications.

Economic models in type 2 diabetes

OBJECTIVE

To identify and critically appraise cost-effectiveness models developed to evaluate type 2 diabetes (T2D) treatments and to assess which types of treatment effects they capture.

RESEARCH DESIGN AND METHODS

A systematic search was performed in MEDLINE, EMBASE, Centre for Reviews and Dissemination databases at the University of York, and Health Economic Evaluation Database for the period to September 2008. The websites of Health Technology Assessment (HTA) bodies in different countries were also screened for relevant models. For each of the identified original models, details of the structure, data in- and outputs were extracted and the overall quality of the model in terms of the combination of structure, assumptions and data inputs were appraised using published criteria.

RESULTS

Seventy-eight articles and 41 HTAs reporting relevant economic evaluations were identified. There were ten models with multiple publications, and a further ten models with one associated publication. The critical review demonstrated that most had the same fundamental structure, used similar micro-simulation techniques and were based on the same key data sources. However, the process for identification of relevant data and their synthesis, and the selection of outcomes lacked transparency. The models differed according to the extent and type of interventions they evaluated and which diabetes complications and treatment-related adverse events were captured. For example, just one model incorporated changes in patient weight, despite the fact that weight gain can be a side-effect of some treatments, and weight loss a potential benefit of others.

CONCLUSIONS

Whilst many economic models exist in T2D, most share common features such as the model type. Identified shortcomings are lack of transparency in data identification and evidence synthesis as well as the selection of the modelled outcomes. Future models should aim to include all relevant treatment outcomes, whether these relate to effects on underlying diabetes and its complications or to short- or long-term side effects of treatment.

Osteoimmunology in orthodontic tooth movement

The skeletal and immune systems share a multitude of regulatory molecules, including cytokines, receptors, signaling molecules, and signaling transducers, thereby mutually influencing each other. In recent years, several novel insights have been attained that have enhanced our current understanding of the detailed mechanisms of osteoimmunology. In orthodontic tooth movement, immune responses mediated by periodontal tissue under mechanical force induce the generation of inflammatory responses with consequent alveolar bone resorption, and many regulators are involved in this process. In this review, we take a closer look at the cellular/molecular mechanisms and signaling involved in osteoimmunology and at relevant research progress in the context of the field of orthodontic tooth movement.

Alveolar Bone Marrow Gli1+ Stem Cells Support Implant Osseointegration

Osseointegration is the key issue for implant success. The in vivo properties of cell populations driving the osseointegration process have remained largely unknown. In the current study, using tissue clearing-based 3-dimensional imaging and transgenic mouse model-based lineage tracing methods, we identified Gli1+ cells within alveolar bone marrow and their progeny as the cell population participating in extraction socket healing and implant osseointegration. These Gli1⁺ cells are surrounding blood vessels and do not express lineage differentiation markers. After tooth extraction and delayed placement of a dental implant, Gli1⁺ cells were activated into proliferation, and their descendants contributed significantly to new bone formation. Ablation of Gli1⁺ cells severely compromised the healing and osseointegration processes. Blockage of canonical Wnt signaling resulted in impaired recruitment of Gli1⁺ cells and compromised bone healing surrounding implants. Collectively, these findings demonstrate that Gli1⁺ cells surrounding alveolar bone marrow vasculature are stem cells supporting dental implant osseointegration. Canonical Wnt signal plays critical roles in regulating Gli1⁺ stem cells.

Characterizing the PAHs in surface waters and snow in the Athabasca region: Implications for identifying hydrological pathways of atmospheric deposition

The composition of polycyclic aromatic hydrocarbons present in snow and surface waters in the Athabasca Oil Sands Region (AOSR) was characterized in order to identify major contributors to the organics detected in rivers and lakes in the region. PAH concentrations, measured by three monitoring programs in 2011, were used to compare the PAH compositions of snow and surface waters across the AOSR. The 2011 dataset includes total (dissolved+particulate) concentrations of thirty-four parent and alkylated PAH compounds in 105 snow, 272 river, and 3 lake samples. The concentration of PAHs in rivers varies seasonally, with the highest values observed in July. The timing of increases in PAH concentrations in rivers coincides with the high river discharge during the spring freshet, indicating that this major hydrological event may play an important role in delivering PAHs to rivers. However, the composition of PAHs present in rivers during this period differs from the composition of PAHs present in snow, suggesting that direct runoff and release of PAHs accumulated on snow may not be the major source of PAHs to the Athabasca River and its tributaries. Instead, snowmelt may contribute indirectly to increases in PAHs due to hydrological processes such as erosion of stream channels, remobilization of PAH-containing sediments, increased catchment runoff, and snowmelt-induced groundwater inputs during this dynamic hydrologic period. Better understanding of transformations of PAH profiles during transport along surface and subsurface flow paths in wetland-dominated boreal catchments would improve identification of potential sources and pathways in the region. The compositional differences highlight the challenges in identifying the origins of PAHs in a region with multiple potential natural and anthropogenic sources particularly when the potential transport pathways include air, soil and water.

Chromosome 11 genomic changes in parathyroid adenoma and hyperplasia: array CGH, FISH, and tissue microarrays

We have used a combination of gene expression profiling, array comparative genomic hybridization (aCGH), fluorescent in situ hybridization (FISH) and tissue microarrays (TMAs) to investigate chromosome 11 genetic changes in subsets of benign parathyroid tumors. Integration of gene expression profiling and aCGH was done using differential gene locus mapping analysis. We have identified three distinct relatively common chromosome 11 genomic changes in various subsets of parathyroid tumors. The simplest and least common of these genomic changes involves translocation of the CCND1 gene with subsequent strong CCND1 expression. This genetic change is essentially limited to parathyroid adenomas (8%), although expression of CCND1 without translocation is common in uremic hyperparathyroidism. Not surprisingly, deletion of the MEN1 locus at 11q13 or loss of a large portion or an entire chromosome 11 was a common finding. This particular genomic change appears to have a prominent effect on the overall results of gene expression profiling and was present in slightly less than one-half of adenomas. Genomic changes in primary nonfamilial hyperplasia were for the most part restricted to 11q13 deletion or loss of chromosome 11. The third genomic change we identified was 11q23 deletion. This genetic change was relatively independent of other chromosome 11 changes and present in slightly less than one-half of adenomas. 11q23 deletion along with relatively strong CCND1 expression was common in uremic hyperparathyroidism.

An intragenic suppressor of the Arabidopsis floral organ identity mutant apetala3-1 functions by suppressing defects in splicing

The Arabidopsis floral organ identity gene APETALA3 (AP3) specifies the identity of petals and stamens in the flower. In flowers mutant for the temperature-sensitive ap3-1 allele, the petals and stamens are partially converted to sepals and carpels, respectively. ap3-1 contains a single nucleotide change in the AP3 gene that alters both an amino acid in the AP3 protein and the 5' splice consensus site for intron 5. Surprisingly, the Ap3-1 mutant phenotype is not due to the missense mutation but instead is due to defects in splicing; specifically, exon 5 is frequently skipped by the splicing machinery at the restrictive temperature. In a screen for suppressors of ap3-1, we isolated an intragenic suppressor, ap3-11, that functions to suppress the splicing defects of ap3-1. Using a reverse transcriptase-polymerase chain reaction assay, we demonstrate that the percentage of full-length exon 5-containing AP3 RNAs correlates with the phenotype of the flowers in both ap3-1 and ap3-11. Rather surprisingly, the ap3-11 suppressor mutation is located in intron 4. One model explaining the function of ap3-11 is that the ap3-11 suppressor creates a novel branch point sequence that causes exon 5 to be more frequently recognized by the splicing machinery. The identification of such a suppressor strongly suggests that exon-scanning models of intron-exon recognition are operative in plants.

Neuroprotective activity of tiagabine in a focal embolic model of cerebral ischemia

Gamma aminobutyric acid (GABA) agonists have been shown to have neuroprotective effects when used after focal or global cerebral ischemia. In this study, we evaluated the neuroprotective effects of a GABA re-uptake inhibitory agent, tiagabine, on focal ischemic brain injury in an embolic model in rats. Tiagabine, injected at 1 h after embolization, significantly reduced brain infarction volume, measured with 2,3,5-triphenyltetrazolium chloride (TTC) histological assay. There were varying degrees of neuroprotective effect exhibited in the other experimental groups however this did not reach significance. These results suggest that tiagabine is neuroprotective when administrated at an early period after the ischemic brain injury.

Giant negative magnetoresistance in Manganese-substituted Zinc Oxide

We report a large negative magnetoresistance in Manganese-substituted Zinc Oxide thin films. This anomalous effect was found to appear in oxygen-deficient films and to increase with the concentration of Manganese. By combining magnetoresistive measurements with magneto-photoluminescence, we demonstrate that the effect can be explained as the result of a magnetically induced transition from hopping to band conduction where the activation energy is caused by the sp-d exchange interaction.

Human immunodeficiency virus type 1 IIIB selected for replication in vivo exhibits increased envelope glycoproteins in virions without alteration in coreceptor usage: separation of in vivo replication from macrophage tropism

Analysis of viral replication and pathogenicity after in vivo selection of human immunodeficiency virus type 1 (HIV-1) attenuated in vitro will help to define the functions involved in replication and pathogenesis in vivo. Using the SCID-hu Thy/Liv mouse and human fetal thymus organ culture as in vivo models, we previously defined HIV-1 env determinants (HXB2/LW) which were reverted for replication in vivo (L. Su et al., Virology 227:46-52, 1997). In this study, we examined the replication of four highly related HIV-1 clones directly derived from Lai/IIIB or after selection in vivo to investigate the envelope gp120 determinants associated with replication in macrophages and in the thymus models in vivo. The LW/C clone derived from the IIIB-infected laboratory worker and HXB2/LW both efficiently infected monocyte-derived macrophages (MDM) and the human thymus. Although the laboratory worker (LW) isolates showed altered tropism from IIIB, they still predominantly used CXCR4 as coreceptors for infecting peripheral blood mononuclear cells, macrophages, and the thymus. Interestingly, a single amino acid mutation in the V3 loop associated with resistance to neutralizing antibodies was also essential for the replication activity of the LW virus in the thymus models but not for its activity in infecting MDM. The LW virions were equally sensitive to a CXCR4 antagonist. We further demonstrated that the LW HIV-1 isolate selected in vivo produced more infectious viral particles that contained higher levels of the Env protein gp120. Thus, selection of the laboratory-attenuated Lai/IIIB isolate in vivo leads to altered tropism but not coreceptor usage of the virus. The acquired replication activity in vivo is correlated with an early A-to-T mutation in the V3 loop and increased virion association of HIV-1 Env gp120, but it is genetically separable from the acquired replication activity in macrophages.