Preparation, characterization and in vitro analysis of novel structured nanofibrous scaffolds for bone tissue engineering

In a previous study, a three-dimensional nanofibrous spiral scaffold for bone tissue engineering was developed, which showed enhanced human osteoblast cell attachment, proliferation and differentiation compared with traditional cylinder scaffolds, owing to the incorporation of spiral structures and nanofiber. However, the application of these scaffolds to bone tissue engineering was limited by their weak mechanical strength. This limitation triggered the design for novel structured scaffolds with reinforced physical characteristics. In this study, spiral polycaprolactone (PCL) nanofibrous scaffolds were inserted into poly(lactide-co-glycolide) (PLGA) microsphere sintered tubular scaffolds to form integrated scaffolds to provide mechanical properties and bioactivity appropriate for bone tissue engineering. Four experiment groups were designed: PLGA cylinder scaffold; PLGA tubular scaffold; PLGA tubular scaffold with PCL spiral structured inner core; PLGA tubular scaffold with PCL nanofiber containing spiral structured inner core. The morphology, porosity and mechanical properties of the scaffolds were characterized. Furthermore, human osteoblastic cells were seeded on these scaffolds, and the cell attachment, proliferation, differentiation and mineralized matrix deposition on the scaffolds were evaluated. The integrated scaffolds had Young's modulus 250-300 MPa, and compressive strength 8-11 MPa under uniaxial compression. With the addition of an inner highly porous insert to the tubular shell, human osteoblast cells seeded on the integrated scaffolds showed slightly higher cell proliferation, 20-25% more alkaline phosphatase expression and twofold higher calcium deposition than those on the cylinder and tubular scaffolds. Furthermore, compared with sintered PLGA cylinder scaffolds, the integrated scaffolds allowed better cellular infiltration Therefore, this design demonstrates great potential for integrated scaffolds in bone tissue engineering applications.

Impaired dopaminergic neurotransmission and microtubule-associated protein tau alterations in human LRRK2 transgenic mice

Mutations in the Leucine Rich Repeat Kinase 2 (LRRK2) gene, first described in 2004 have now emerged as the most important genetic finding in both autosomal dominant and sporadic Parkinson's disease (PD). While a formidable research effort has ensued since the initial gene discovery, little is known of either the normal or the pathological role of LRRK2. We have created lines of mice that express human wild-type (hWT) or G2019S Lrrk2 via bacterial artificial chromosome (BAC) transgenesis. In vivo analysis of the dopaminergic system revealed abnormal dopamine neurotransmission in both hWT and G2019S transgenic mice evidenced by a decrease in extra-cellular dopamine levels, which was detected without pharmacological manipulation. Immunopathological analysis revealed changes in localization and increased phosphorylation of microtubule binding protein tau in G2019S mice. Quantitative biochemical analysis confirmed the presence of differential phospho-tau species in G2019S mice but surprisingly, upon dephosphorylation the tau isoform banding pattern in G2019S mice remained altered. This suggests that other post-translational modifications of tau occur in G2019S mice. We hypothesize that Lrrk2 may impact on tau processing which subsequently leads to increased phosphorylation. Our models will be useful for further understanding of the mechanistic actions of LRRK2 and future therapeutic screening.

Telmisartan alleviates rosiglitazone-induced bone loss in ovariectomized spontaneous hypertensive rats

In the present study, we systematically examined telmisartan, an angiotensin AT(1) receptor antagonist, on rosiglitazone-induced bone loss in ovariectomized spontaneously hypertensive rats. Telmisartan (5 mg/kg/d, 90 days) was found to be able to significantly alleviate rosiglitazone (10 mg/kg/d, 90 days)-induced decrease in BMD of femur and lumbar vertebrae. The BMD changes were associated with positive biomechanical changes of lumbar vertebrae, improvements in microarchitecture of tibial metaphysic and normalized serum osteocalcin (OC) levels and urinary deoxypyridinoline/creatinine (DPD/Cr) ratio. MicroCT analysis of the tibial metaphysis showed that telmisartan significantly prevented the decreases in bone volume/tissue volume (BV/TV), connect density (Conn. D.), trabecular number (Tb. N.) and trabecular thickness (Tb. Th.), and increase in trabecular separation (Tb. Sp.) induced by rosiglitazone. Histomorphometric analysis also showed that telmisartan had protective effects on rosiglitazone-reduced bone formation indices such as histomorphometric bone volume fraction (BV/TV-Histo), mineralizing surface/bone surface (MS/BS), mineral apposition rate (MAR) and bone formation rate (BFR/BS). Our study clearly showed that telmisartan alleviated rosiglitazone-induced bone loss in ovariectomized spontaneous hypertensive rats. The relief of bone loss provides a possible therapeutic application of telmisartan with rosiglitazone for the treatment of elderly women patients afflicted with metabolic syndrome.

Contribution of magnetic resonance imaging to prenatal differential diagnosis of renal tumors: report of two cases and review of the literature

Enlargement of a kidney on prenatal imaging is usually due to hydronephrosis or cystic renal disease, and much less often results from solid tumors such as mesoblastic nephroma, Wilms' tumor, nephroblastomatosis, renal sarcoma, and angiomyolipoma. All can be diagnosed by ultrasound. Magnetic resonance imaging is useful not only in confirming the presence of a renal mass, but also in the evaluation of the contralateral kidney for subtle abnormalities. We present one case each of Wilms' tumor and mesoblastic nephroma, both detected on antenatal ultrasound and further studied with fetal magnetic resonance imaging.

Characterization of cis elements of the probasin promoter necessary for prostate-specific gene expression

BACKGROUND

The androgen-regulated probasin (PB) promoter has been used extensively to target transgenes to the prostate in transgenic mice; however, limited data exist on the mechanism that dictates prostate-specific gene expression. Tissue-specific gene expression involves synergistic effects among transcription factors associated in a complex bound to cis-acting DNA elements.

METHODS

Using comprehensive linker scan mutagenesis, enzyme mobility shift and supershift assays, chromatin immunoprecipitation, and transgenic animal studies, we have extensively characterized the prostate-specific PB promoter.

RESULTS

We identified a series of nonreceptor transcription factors that are bound to the prostate-specific rat PB promoter. These factors include several ubiquitously distributed proteins known to participate in steroid receptor-mediated transcription. In addition, we identified two tissue-specific DNA elements that are crucial in directing prostate-specific PB expression, and confirmed the functional importance of both elements in transgenic animal studies. These two elements are functionally interchangeable and can be bound by multiple protein complexes, including the forkhead transcription factor FoxA1, a "pioneer factor" that has a restricted distribution to some cells type that are ectoderm and endoderm in origin. Using transgenic mice, we further demonstrate that the minimal PB promoter region (-244/-96 bp) that encompasses these tissue-specific elements results in prostate-specific gene expression in transgenic mice, contains androgen receptor and FoxA1-binding sites, as well as ubiquitous transcription factor binding sites.

CONCLUSION

We propose that these sequence-specific DNA-binding proteins, including tissue-restricted and ubiquitous factors, create the first level of transcriptional control, which responds to intracellular pathways that directs prostate-specific gene expression.

Skeletal phenotype of mice with a null mutation in Cav 1.3 L-type calcium channel

This study aimed to understand the role of Cav1.3, one of the four L-type voltage sensitive calcium channels (VSCC) alpha(1) subunits, in the skeletal response to mechanical loading and intermittent PTH treatment. The Cav1.3 mRNA is expressed in osteoblasts. The Cav1.3 mRNA level in male wild type mice is higher than those in female. Loss of Cav1.3 resulted in a smaller skeleton in male mice as indicated by significantly lower body weight, less bone mineral content and smaller cross-sectional area of femoral midshaft. However, the osteogenic response to mechanical loading of the ulna was normal in Cav1.3(-/-) compared to the normal control mice. Male mice Cav1.3(-/-) were then treated daily with PTH at a dose of 40 microg/kg. A 6-week course of intermittent PTH treatment enhanced bone mineral content and mechanical strength equally in wild type control and Cav1.3 null mice. We also found that Cav1.2 subunit significantly increases in the absence of Cav1.3 gene. In conclusion, Cav1.3 is involved in bone metabolism, especially in male mice. Cav1.3 does not mediate osteoblast response to mechanical loading and PTH. Our data suggest that Cav1.1 and Cav1.2 subunits may substitute for Cav1.3 to maintain bone response to mechanical loading.

Jak/STAT signaling is involved in the inflammatory infiltration of the kidneys in MRL/lpr mice

Cytokines are known to play an important role in the pathogenesis of lupus nephritis (LN) and the Jak/STAT (Janus kinase-signal transducer and activator of transcription factor) pathway is important in mediating signal transduction of cytokines. This study examined the pathogenic role of Jak/STAT signaling in LN. MRL/lpr mice were either treated with a selective Jak2 inhibitor tyrphostin AG490 or with vehicle alone from 12 weeks of age until being sacrificed at week 20. AG490 significantly inhibited the phosphorylation of Jak2 and STAT1 (p < 0.05). Compared with the vehicle-treated mice, AG490 treatment significantly reduced proteinuria, improved renal function and suppressed histological lesions of the kidneys and salivary glands (p < 0.05). AG490 treatment significantly inhibited the renal expression of monocyte chemotactic protein (MCP)-1, interferon (IFN)-gamma and class II MHC, which was accompanied by reduced renal infiltration of T cells and macrophages (p < 0.05). In addition, AG490 treatment resulted in a decrease in serum anti-double-stranded DNA (anti-dsDNA) antibody and attenuated the deposition of IgG and C3 in the kidneys (p < 0.05). This study demonstrated that Jak/STAT pathway is implicated in the progression of renal inflammation in MRL/lpr mice and targeting this pathway may provide a potential therapeutic approach for LN.

Comparative In Vivo Study on the Desensitizing Efficacy of Dentin Desensitizers and One-bottle Self-etching Adhesives

Dentin desensitizers and one-bottle self-etching adhesives can significantly reduce dentin hypersensitivity. Clinical desensitizing effectiveness depends on the individual dentin desensitizers/adhesives used.

Abstract 1955: Bone-marrow-derived cells incorporate into the prostate during regrowth

It is necessary to understand mechanisms of castrate resistant prostate cancer development and progression. As prostate cancer transitions from androgen dependent to castrate resistant, subsequent recurrence involves increased growth of the cancer epithelial cells. Understanding prostate regrowth in a normal prostate will allow us to better understand growth in castrate resistant prostate cancer. We hypothesized that altered chemokine signaling which accompanies the loss and subsequent return of androgen signaling results in the recruitment of immune cells to the prostate microenvironment from the bone marrow. A chimeric mouse model with GFP-labeled bone marrow was used to allow us to identify bone marrow cells recruited to the prostate. We studied how bone marrow derived cells (BMDCs) contributed to an androgen refractory response, specifically prostate regrowth. In a similar mouse model we used GFP-labeled mesenchymal stem cells (MSCs) to study this specific subset of BMDCs in response to prostate regrowth. Host mice were castrated or left intact as a control. Testosterone was given to the chimeric mice. The intact and castrated control mice had a low number of BMDCs recruited to the prostate. However, three and seven days following exogenous testosterone administration resulted in a dramatic increase in BMDC recruitment during prostate regrowth. GFP labeled MSC cells were also recruited to the prostate at three days following treatment with exogenous testosterone. Interestingly, even after four weeks the fully regrown prostates retained BMDCs that appeared to be incorporated in the epithelial compartment. Double immunofluorescence staining showed that a subset of BMDCs gained the expression of androgen receptor; p63, a basal epithelial marker; and cytokeratin 8, a luminal epithelial marker, in the prostate. Rosa26 expressing MSCs injected into GFP mice showed prostate co-localization of ß-galactosidase and GFP, suggesting that MSCs fused with resident prostate epithelial cells during regrowth. The recruitment and eventual incorporation of BMDCs in the prostate suggests a mechanism for exogenous cells in castration-resistant prostate cancer growth. This result has implications for castrate-resistant prostate cancer growth, as it too may be a result of MSC recruitment, incorporation, and fusion. NIH grants F31 GM079879 (VRP), CA108646 and CA126505 (NAB).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1955.

Abstract 1231: Nuclear Factor I family members interact with FoxA1 to regulate androgen responsive promoters

Forkhead (Fox) proteins are an important class of transcription factors (TFs) that act as molecular “pioneers” by increasing chromatin accessibility. The ability of FoxA1 to act in this manner allows for the subsequent nucleation of responsive promoters by additional, tissue specific TFs, allowing for gene regulation. Our laboratory has previously shown that FoxA1 interacts directly with the androgen receptor (AR), and that the expression of FoxA1 is essential for normal prostate maturation and differentiation. Thus, the ability of FoxA1 to enter a transcriptional complex with AR and other TFs contributes to tissue-specific gene expression in the prostate, and determining the components of FoxA1/AR TF complexes will identify additional targets for the treatment of castrate-resistant PCa.

In order to identify additional proteins that interact with FoxA1, we ectopically expressed dual-affinity tagged FoxA1 in the human PCa cell line LNCaP. Following tandem purification and mass spectrometric analysis, we identified several FoxA1-interacting proteins, including Nuclear Factor I x (NFIx). NFIx is a member of the Nuclear Factor family of TFs, consisting of NFIa, NFIb, NFIc, and NFIx. Co-immunoprecipitation studies verify that NFI family members interact with FoxA1, and Chromatin immunoprecipitation (ChIP) experiments indicate NFI family members bind to androgen regulated, prostate-specific promoters. Finally, transient transfection experiments indicate that NFI family members modulate the androgenic stimulation of the Probasin and PSA promoters both in the presence and absence of FoxA1.

In summary, we have identified NFIx as a novel FoxA1 interacting protein. NFI family members act to modulate the transcriptional activity of FoxA1 and AR on prostate-specific target promoters.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1231.

MicroRNA-25 functions in regulation of pigmentation by targeting the transcription factor MITF in Alpaca (Lama pacos) skin melanocytes

Although the influence of endocrine factors is well established, the molecular and cellular mechanisms controlling coat color are not completely understood. A major mechanism for post-transcriptional regulation of gene expression is through the action of microRNAs (miRNAs), which anneal to the 3' untranslated region of mRNAs in a sequence-specific fashion and either block translation or promote transcript degradation. In this study, we investigated the expression of miRNAs in the skin of alpacas with brown vs white coat color using a microarray screen; identified potential mRNA targets for identified miRNAs among coat color genes; and subsequently determined the ability of a specific, differentially expressed miRNA (miR-25) to suppress expression of micropthalmia-associated transcription factor (MITF), a predicted miR-25 target gene that regulates genes linked to coat color. Expression of 10 different miRNA species in the skin of alpacas with brown vs white coat color was identified from microarray screens. Of the 10 alpaca skin miRNAs identified, predicted binding sites in the 3' untranslated region of RNAs encoding for known genes linked to coat color were primarily for miR-25, but sites were also identified for miR-129 and miR-377. Potential miR-25 binding sites were present in transcripts encoding for 11 coat color genes, including MITF. An inverse relationship between transcript abundance for MITF and miR-25 was observed in skin samples collected from alpacas with white vs brown coat color. Furthermore, overexpression of miR-25 in cultured melanocytes reduced MITF mRNA and protein abundance and corresponding mRNA abundance for the MITF-regulated enzymes tyrosinase and tyrosinase-related protein 1. Results support a novel functional role for miRNA-25 in the regulation of gene expression linked to coat color.

Hyperglycemia suppresses ABCA1 expression in vascular smooth muscle cells

Hyperglycemia is a major risk factor for atherosclerotic disease. The ATP-binding cassette transporter A1 (ABCA1) functions as a pivotal regulator of lipid efflux from cells to apolipoproteins and is thus involved in lowering the risk of atherosclerosis. In this study, we have examined the glucose-mediated regulation of the ABCA1 gene expression in vascular smooth muscle cells. ABCA1 expression was examined by real-time polymerase chain reaction (PCR), Western blot analysis, and reporter gene assay. The results showed that the expression of the ABCA1 mRNA and protein decreased after the cells were treated with 22.4 mM glucose for 48 h. The transcriptional activity of the ABCA1 promoter paralleled the endogenous expression of the ABCA1 gene. Next, we used inhibitors of certain signal transduction pathways to demonstrate that the glucose-induced ABCA1 suppression is sensitive to the p38-mitogen-activated protein kinase (MAPK) inhibitors. The expression of a constitutively active form of p38-MAPK in the cells inhibited the ABCA1 promoter activity, irrespective of the presence of glucose. A dominant-negative mutant of p38-MAPK abrogated the inhibitory effect of glucose on the ABCA1 promoter activity. These results indicate that the glucose-induced suppression of ABCA1 expression is partially mediated by the activation of the p38-MAPK pathway.

Early Onset of Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) after Allogeneic Haematopoietic Stem Cell Transplantation: Case Report and Review of the Literature

Severe hyponatraemia and syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a rare but fatal complication following stem cell transplantation (SCT). This case report details a patient with early-onset SIADH after allogeneic haematopoietic SCT (allo-HSCT) and reviews the literature on risk factors for the development of this condition. The patient, who had chronic myelogenous leukaemia, developed acute graft-versus-host disease (GVHD) on day 5 after allo-HSCT, which was relieved promptly by steroids. On day 18, he presented with hyponatraemia, which was refractory. Despite intensive restriction of fluid and administration of hypertonic saline, his condition worsened and he died of multiple systemic organ dysfunction. A review of the literature reveals that early-onset SIADH following SCT is insidious, but progresses rapidly. The severity of the disorder is underestimated because of the non-specific clinical features and the lack of effective treatment. Myeloablative conditioning and acute GVHD are two major important predisposing factors in SIADH.

Effects of n-3 Polyunsaturated Fatty Acid Therapy on Plasma Inflammatory Markers and N-Terminal Pro-brain Natriuretic Peptide in Elderly Patients with Chronic Heart Failure

Several previous studies have suggested that n-3 polyunsaturated fatty acids ( n-3 PUFA) can exert favourable effects in patients with heart failure, but the mechanisms involved are not fully understood. This study was designed to investigate the effects of n-3 PUFA on circulating inflammatory markers and N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with heart failure. Seventy-six patients with heart failure were randomly assigned to receive 2 g/day of n-3 PUFA or placebo for 3 months. Treatment with n-3 PUFA significantly decreased plasma levels of tumour necrosis factor, interleukin-6, intercellular adhesion molecule 1 and NT-proBNP. Left ventricular ejection fraction showed a small, non-significant improvement. High-sensitivity C-reactive protein levels decreased significantly in smokers after n-3 PUFA treatment. Thus, n-3 PUFA can reduce levels of plasma inflammatory markers and NT-proBNP as biomarkers of risk stratification in patients with heart failure. n-3 PUFA may offer a novel therapy for heart failure.

The human papillomavirus type 58 E7 oncoprotein modulates cell cycle regulatory proteins and abrogates cell cycle checkpoints

HPV type 58 (HPV-58) is the third most common HPV type in cervical cancer from Eastern Asia, yet little is known about how it promotes carcinogenesis. In this study, we demonstrate that HPV-58 E7 significantly promoted the proliferation and extended the lifespan of primary human keratinocytes (PHKs). HPV-58 E7 abrogated the G1 and the postmitotic checkpoints, although less efficiently than HPV-16 E7. Consistent with these observations, HPV-58 E7 down-regulated the cellular tumor suppressor pRb to a lesser extent than HPV-16 E7. Similar to HPV-16 E7 expressing PHKs, Cdk2 remained active in HPV-58 E7 expressing PHKs despite the presence of elevated levels of p53 and p21. Interestingly, HPV-58 E7 down-regulated p130 more efficiently than HPV-16 E7. Our study demonstrates a correlation between the ability of down-regulating pRb/p130 and abrogating cell cycle checkpoints by HPV-58 E7, which also correlates with the biological risks of cervical cancer progression associated with HPV-58 infection.

A linkage map of common carp (Cyprinus carpio) based on AFLP and microsatellite markers

Common carp (Cyprinus carpio) is an important fish for aquaculture, but genomics of this species is still in its infancy. In this study, a linkage map of common carp based on Amplified Fragment Length Polymorphism (AFLP) and microsatellite (SSR) markers has been generated using gynogenetic haploids. Of 926 markers genotyped, 151 (149 AFLPs, two SSRs) were distorted and eliminated from the linkage analyses. A total of 699 AFLP and 20 microsatellite (SSR) markers were assigned to the map, which comprised 64 linkage groups and covered 5506.9 cM Kosambi, with an average interval distance of 7.66 cM Kosambi. The normality tests on interval map distances showed a non-normal marker distribution. Visual inspection of the map distance distribution histogram showed a cluster of interval map distances on the left side of the chart, which suggested the occurrence of AFLP marker clusters. On the other hand, the lack of an obvious cluster on the right side showed that there were a few big gaps which need more markers to bridge. The correlation analysis showed a highly significant relatedness between the length of linkage group and the number of markers, indicating that the AFLP markers in this map were randomly distributed among different linkage groups. This study is helpful for research into the common carp genome and for further studies of genetics and marker-assisted breeding in this species.