A pH-responsive metal-organic framework for the co-delivery of HIF-2α siRNA and curcumin for enhanced therapy of osteoarthritis

The occurrence of osteoarthritis (OA) is highly correlated with the reduction of joint lubrication performance, in which persistent excessive inflammation and irreversible destruction of cartilage dominate the mechanism. The inadequate response to monotherapy methods, suboptimal efficacy caused by undesirable bioavailability, short retention, and lack of stimulus-responsiveness, are few unresolved issues. Herein, we report a pH-responsive metal-organic framework (MOF), namely, MIL-101-NH₂, for the co-delivery of anti-inflammatory drug curcumin (CCM) and small interfering RNA (siRNA) for hypoxia inducible factor (HIF-2α). CCM and siRNA were loaded via encapsulation and surface coordination ability of MIL-101-NH₂. Our vitro tests showed that MIL-101-NH₂ protected siRNA from nuclease degradation by lysosomal escape. The pH-responsive MIL-101-NH₂ gradually collapsed in an acidic OA microenvironment to release the CCM payloads to down-regulate the level of pro-inflammatory cytokines, and to release the siRNA payloads to cleave the target HIF-2α mRNA for gene-silencing therapy, ultimately exhibiting the synergetic therapeutic efficacy by silencing HIF-2α genes accompanied by inhibiting the inflammation response and cartilage degeneration of OA. The hybrid material reported herein exhibited promising potential performance for OA therapy as supported by both in vitro and in vivo studies and may offer an efficacious therapeutic strategy for OA utilizing MOFs as host materials.

NIR-PTT/ROS-Scavenging/Oxygen-Enriched Synergetic Therapy for Rheumatoid Arthritis by a pH-Responsive Hybrid CeO2-ZIF-8 Coated with Polydopamine

Rheumatoid arthritis (RA) is an inflammatory type of arthritis that causes joint pain and damage. The inflammatory cell infiltration (e.g., M1 macrophages), the poor O₂ supply at the joint, and the excess reactive oxygen species (ROS)-induced oxidative injury are the main causes of RA. We herein report a polydopamine (PDA)-coated CeO₂-dopped zeolitic imidazolate framework-8 (ZIF-8) nanocomposite CeO₂-ZIF-8@PDA (denoted as CZP) that can synergistically treat RA. Under near-infrared (NIR) light irradiation, PDA efficiently scavenges ROS and results in an increased temperature in the inflamed area because of its good light-to-heat conversion efficiency. The rise of temperature serves to obliterate hyper-proliferative inflammatory cells accumulated in the diseased area while vastly promoting the collapse of the acidic-responsive skeleton of ZIF-8 to release the encapsulated CeO₂. The released CeO₂ exerts its catalase-like activity to relieve hypoxia by generating oxygen via the decomposition of H₂O₂ highly expressed in the inflammatory sites. Thus, the constructed CZP composite can treat RA through NIR-photothermal/ROS-scavenging/oxygen-enriched combinative therapy and show good regression of pro-inflammatory cytokines and hypoxia-inducible factor-1α (HIF-1α) in vitro and promising therapeutic effect on RA in rat models. The multimodal nano-platform reported herein is expected to shed light on the design of synergistic therapeutic nanomedicine for effective RA therapy.

Metallic Glacial Glass Formation by a First-Order Liquid-Liquid Transition

The glacial phase, with an apparently glassy structure, can be formed by a first-order transition in some molecular-glass-forming supercooled liquids. Here we report the formation of metallic glacial glass (MGG) from the precursor of a rare-earth-element-based metallic glass via the first-order phase transition in its supercooled liquid. The excellent glass-forming ability of the precursor ensures the MGG to be successfully fabricated into bulk samples (with a minimal critical diameter exceeding 3 mm). Distinct enthalpy, structure, and property changes are detected between MGG and metallic glass, and the reversed "melting-like" transition from the glacial phase to the supercooled liquid is observed in fast differential scanning calorimetry. The kinetics of MGG formation is reflected by a continuous heating transformation diagram, with the phase transition pathways measured at different heating rates taken into account. The finding supports the scenario of liquid-liquid transition in metallic-glass-forming liquids.

Distortion of Local Atomic Structures in Amorphous Ge-Sb-Te Phase Change Materials

The local atomic structures of amorphous Ge-Sb-Te phase-change materials have yet to be clarified and the rapid crystal-amorphous phase change resulting in distinct optical contrast is not well understood. We report the direct observation of local atomic structures in amorphous Ge_{2}Sb_{2}Te_{5} using "local" reverse Monte Carlo modeling dedicated to an angstrom-beam electron diffraction analysis. The results corroborated the existence of local structures with rocksalt crystal-like topology that were greatly distorted compared to the crystal symmetry. This distortion resulted in the breaking of ideal octahedral atomic environments, thereby forming local disordered structures that basically satisfied the overall amorphous structure factor. The crystal-like distorted octahedral structures could be the main building blocks in the formation of the overall amorphous structure of Ge-Sb-Te.

Abstract P2-04-03: Epigenomic analysis of cancer stem cell (CSC)-enriched triple-negative breast cancer (TNBC) populations reveals gene regulatory circuitry and novel tumor cell vulnerabilities

Tumor-initiating cells (TICs), also termed cancer stem cells (CSCs) are involved in breast cancer chemoresistance, metastasis and disease progression. To pinpoint tumor cell vulnerabilities and transcriptional drivers of therapeutic relevance, we have characterized the triple negative breast cancer (TNBC) CSC transcriptional landscape using epigenome mapping and nucleosome occupancy determination. We identify a set of transcriptional regulators and signaling mediators that enforce the cancer stem cell state and instruct potential therapeutic strategies.

The basal epithelial marker, integrin-β4 (ITGB4), can be used to stratify mesenchymal-like triple-negative breast cancer (TNBC) cells into populations of low and high tumor-initiating ability in vivo. We used ChIP-seq to measure H3K27ac occupancy and map the transcriptional enhancers in SUM159 cells segregated into ITGB4HI (High tumor initiating ability) and ITGB4LOW (Low tumor initiating ability) populations. Gene-enhancer linking and comparative analysis of enhancer usage revealed an epigenomically defined set of genes that are candidate drivers of the CSC cell state, including GSK3β, DNA-binding transcription factors and cellular adhesion proteins. To further define the chromatin architecture and transcriptional regulatory circuitry that underlies CSC state, we deployed ATAC-seq (Assay for Transposase-Accessible Chromatin with high throughput sequencing) within ITGB4HI and ITGB4LOW populations. By pairing nucleosome occupancy and transcription factor kinetics, we created enhancer-linked transcriptional regulatory circuitry of these tumor-initiating cells.

Together, the isolation of partially mesenchymal ITGB4HI CSCs, coupled with enhancer mapping and distillation of transcriptional regulatory circuitry from these cells enable the identification of cancer vulnerabilities and therapeutic opportunities for high-risk patients with TNBC.

Citation Format: Guenther MG, Lambert AW, Chen MW, Fiore C, Eaton M, Orlando D, Bierie B, Weinberg RA, Fritz CC, Olson ER. Epigenomic analysis of cancer stem cell (CSC)-enriched triple-negative breast cancer (TNBC) populations reveals gene regulatory circuitry and novel tumor cell vulnerabilities [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-04-03.

Abstract P6-11-18: A novel subgroup of estrogen receptor positive breast cancer may benefit from super-enhancer guided patient selection for retinoic acid receptor α agonist treatment

Endocrine-resistance remains a major challenge for treatment of breast cancer. Multiple mechanisms for endocrine resistance have been proposed, including altered expression of ER co-regulators such as Retinoic Acid Receptor Alpha (RARα). Furthermore, crosstalk between estradiol and RA signaling is known and upregulation of RARα has been observed in tamoxifen resistance. We propose a novel treatment paradigm for a newly-defined subset of HR+ patients based on our discovery of a super-enhancer (SE) associated with the RARA locus. SEs are large, highly active chromatin regions that pinpoint cancer vulnerabilities. The RARA SE-identified vulnerability can be targeted using the potent, selective, and metabolically stable RARα agonist SY-1425 (tamibarotene). SY-1425 is approved in Japan to treat Acute Promyelocytic Leukemia, has a well-established efficacy and safety profile, and may enhance response to hormonal therapy (HT) in this newly-defined subset of HR+ patients potentially delaying the need for alternate treatment.

Tumor samples from 42 breast cancer patients were analyzed across a range of molecular subtypes. We identified an SE linked to the RARA gene in 54.5% of the hormone positive patient samples. RARA SEs predicted sensitivity to SY-1425 in 12 breast cancer cell lines confirming their functional role, and showed a correlation with RARA gene expression. A panel of 37 breast cancer cell lines was tested for SY-1425 anti-proliferative activity and gene expression levels, and identified RARA as the single best predictor of response. Proliferation of RARA-high cells was inhibited by SY-1425 with low nanomolar EC50s. Transcriptional profiling was performed on 4 HR+ and 3 HER2+/HR- breast cancer cell lines and analyzed by GSEA to examine the molecular response to SY-1425. Signatures for growth including E2F, MYC, DNA replication, and cell cycle were significantly downregulated while retinol metabolism and luminal signaling were upregulated. Estrogen signaling was also significantly altered by SY-1425, supporting known crosstalk between RARα and ER. Consistent with differentiation, CYP26A1 and VE-Cadherin were induced and Actin and Ki67 were diminished at relevant concentrations of SY-1425 and could serve as pharmacodynamic markers of response.

To test responses to SY-1425 in vivo, two cell line-derived models and two patient-derived breast cancer models (one RARA-high, and one RARA-low each) were treated with SY-1425. SY-1425 inhibited tumor growth in the RARA-high models, but not the RARA-low models (43% versus 0% TGI). Consistent with the observed changes in transcription, SY-1425 in combination with tamoxifen synergistically inhibited proliferation of RARA-high breast cancer cell lines.

Although a few clinical studies have investigated the use of ATRA in HR+ breast cancer without success, our results suggest that patient selection based on the RARA SE may predict which HR+ breast cancer patients could derive benefit by adding an RARα agonist to HT. The potential to prolong or increase the clinical effect of anti-estrogen therapy with SY-1425, which has improved potency, selectivity, and PK stability versus ATRA, would be an attractive strategy to explore.

An ultrahigh volumetric capacitance of squeezable three-dimensional bicontinuous nanoporous graphene

Graphene with a large specific surface area and high conductivity has a large specific capacitance. However, its volumetric capacitance is usually very low because the restacking of 2D graphene sheets leads to the loss of the large ion-accessible surface area. Here we report squeezable bicontinuous nanoporous nitrogen-doped graphene, which is extremely flexible and can tolerate large volume contraction by mechanical compression without the face-to-face restacking occurring. The compressed nanoporous N-doped graphene with a large ion accessible surface area and high conductivity shows an ultrahigh volumetric capacitance of ∼300 F cm^-3 together with excellent cycling stability and high rate performance.

Initial Atomic Motion Immediately Following Femtosecond-Laser Excitation in Phase-Change Materials

Despite the fact that phase-change materials are widely used for data storage, no consensus exists on the unique mechanism of their ultrafast phase change and its accompanied large and rapid optical change. By using the pump-probe observation method combining a femtosecond optical laser and an x-ray free-electron laser, we substantiate experimentally that, in both GeTe and Ge_{2}Sb_{2}Te_{5} crystals, rattling motion of mainly Ge atoms takes place with keeping the off-center position just after femtosecond-optical-laser irradiation, which eventually leads to a higher symmetry or disordered state. This very initial rattling motion in the undistorted lattice can be related to instantaneous optical change due to the loss of resonant bonding that characterizes GeTe-based phase change materials. Based on the amorphous structure derived by first-principles molecular dynamics simulation, we infer a plausible ultrafast amorphization mechanism via nonmelting.

Macrodeformation Twins in Single-Crystal Aluminum

Deformation twinning in pure aluminum has been considered to be a unique property of nanostructured aluminum. A lingering mystery is whether deformation twinning occurs in coarse-grained or single-crystal aluminum at scales beyond nanotwins. Here, we present the first experimental demonstration of macrodeformation twins in single-crystal aluminum formed under an ultrahigh strain rate (∼10^{6}  s^{-1}) and large shear strain (200%) via dynamic equal channel angular pressing. Large-scale molecular dynamics simulations suggest that the frustration of subsonic dislocation motion leads to transonic deformation twinning. Deformation twinning is rooted in the rate dependences of dislocation motion and twinning, which are coupled, complementary processes during severe plastic deformation under ultrahigh strain rates.

Quantitative assessment of the effects of the EPHX1 Tyr113His polymorphism on lung and breast cancer

The association between the microsomal epoxide hydrolase 1 gene (EPHX1) Tyr113His polymorphism and lung cancer and breast cancer risk has been reported in many recent studies, but there is no consensus among the results. Thus, we examined the association between the EPHX1 Tyr113His polymorphism and lung cancer through a meta-analysis. A comprehensive literature search was performed using the Pubmed and Embase databases. Odds ratios with 95% confidence intervals were used to assess the strength of associations. Our meta-analysis suggested that the Tyr113His polymorphism was associated with lung cancer risk in Asians under 3 genetic models, including a C vs T, CC vs TT, and recessive model. However, the risk was decreased in Caucasians under the genetic models, including a C vs T, CC vs TT, or CT vs TT, dominant, and recessive model. In contrast, there was no association with breast cancer risk for any of the genetic models. Our meta-analysis suggested that the EPHX1 Tyr113His polymorphism may be a risk factor for lung cancer in Asians, whereas it may be a decreased risk factor among Caucasians. However, this polymorphism was not found to be associated with breast cancer.

EPHX1 Tyr113His and His139Arg polymorphisms in esophageal cancer risk: a meta-analysis

Microsomal epoxide hydrolase 1 (EPHX1) is an important biological phase II metabolic enzyme that is extensively involved in the metabolism of diverse environmental carcinogens such as polycyclic aromatic hydrocarbons and heterocyclic amines. Many articles have reported the association between EPHX1 (Tyr113His and His139Arg) polymorphisms and esophageal cancer risk, but the results are controversial. This study aimed to identify the association between EPHX1 (Tyr113His and His139Arg) polymorphisms and esophageal cancer risk by meta-analysis. The odds ratio (OR) with 95% confidence interval (95%CI) was used to evaluate the strength of the associations. Heterogeneity was estimated by the chi-square-based Q-statistic test and the P value. Meanwhile, the random-effect or fixed-effect model was used according to the between-study heterogeneity. Begg's funnel plot and the Egger test were performed to assess the publication bias of articles. Finally, 8 case-control studies involving 1158 cases and 1868 controls for the Tyr113His polymorphism and 7 case-control studies involving 901 cases and 1615 controls for the His139Arg polymorphism were included in this meta-analysis. Meta-analysis showed that the Tyr113His polymorphism was a stronger power trend towards risk for esophageal cancer using a recessive model (CC versus CT+TT, OR = 1.204, 95%CI = 1.001-1.450, P = 0.049). However, no significant associated risk was found between the His139Arg polymorphism and esophageal cancer. These findings suggest that the Tyr113His polymorphism might be a stronger power trend towards risk for esophageal cancer. However, no evidence was found for the association between the EPHX1 His139Arg polymorphism and esophageal cancer risk.

First-order liquid-liquid phase transition in cerium

We report the first experimental observation of a liquid-liquid phase transition in the monatomic liquid metal cerium, by means of in situ high-pressure high-temperature x-ray diffraction experiments. At 13 GPa, upon increasing temperature from 1550 to 1900 K high-density liquid transforms to a low-density liquid, with a density difference of 14%. Theoretic models based on ab initio calculations are built to investigate the observed phase behavior of the liquids at various pressures. The results suggest that the transition primarily originates from the delocalization of f electrons and is deemed to be of the first order that terminates at a critical point.

Structural origins of the excellent glass forming ability of Pd40Ni40P20

We report a hybrid atomic packing scheme comprised of a covalent-bond-mediated "stereochemical" structure and a densely packed icosahedron in a bulk metallic glass Pd40Ni40P20. The coexistence of two atomic packing models can simultaneously satisfy the criteria for both the charge saturation of the metalloid element and the densest atomic packing of the metallic elements. The hybrid packing scheme uncovers the structural origins of the excellent glass forming ability of Pd40Ni40P20 and has important implications in understanding the bulk metallic glass formation of metal-metalloid alloys.

Atomic structure of nanoclusters in oxide-dispersion-strengthened steels

Oxide-dispersion-strengthened steels are the most promising structural materials for next-generation nuclear energy systems because of their excellent resistance to both irradiation damage and high-temperature creep. Although it has been known for a decade that the extraordinary mechanical properties of oxide-dispersion-strengthened steels originate from highly stabilized oxide nanoclusters with a size smaller than 5 nm, the structure of these nanoclusters has not been clarified and remains as one of the most important scientific issues in nuclear materials research. Here we report the atomic-scale characterization of the oxide nanoclusters using state-of-the-art Cs-corrected transmission electron microscopy. This study provides compelling evidence that the nanoclusters have a defective NaCl structure with a high lattice coherency with the bcc steel matrix. Plenty of point defects as well as strong structural affinity of nanoclusters with the steel matrix seem to be the most important reasons for the unusual stability of the clusters at high temperatures and in intensive neutron irradiation fields.

Characterization of nanoscale mechanical heterogeneity in a metallic glass by dynamic force microscopy

We report nanoscale mechanical heterogeneity of a metallic glass characterized by dynamic force microscopy. Apparent energy dissipation with a variation of ~12%, originating from nonuniform distribution of local viscoelasticity, was observed. The correlation length of the heterogeneity was measured to be ~2.5 nm, consistent with the dimension of shear transformation zones for plastic flow. This study provides the first experimental evidence on the nanoscale viscoelastic heterogeneity in metallic glasses and may fill the gap between atomic models and macroscopic glass properties.

Non-testing approaches under REACH--help or hindrance? Perspectives from a practitioner within industry

Legislation such as REACH strongly advocates the use of alternative approaches including in vitro, (Q)SARs, and chemical categories as a means to satisfy the information requirements for risk assessment. One of the most promising alternative approaches is that of chemical categories, where the underlying hypothesis is that the compounds within the category are similar and therefore should have similar biological activities. The challenge lies in characterizing the chemicals, understanding the mode/mechanism of action for the activity of interest and deriving a way of relating these together to form inferences about the likely activity outcomes. (Q)SARs are underpinned by the same hypothesis but are packaged in a more formalized manner. Since the publication of the White Paper for REACH, there have been a number of efforts aimed at developing tools, approaches and techniques for (Q)SARs and read-across for regulatory purposes. While technical guidance is available, there still remains little practical guidance about how these approaches can or should be applied in either the evaluation of existing (Q)SARs or in the formation of robust categories. Here we provide a perspective of how some of these approaches have been utilized to address our in-house REACH requirements.

Oxygen reduction in nanoporous metal-ionic liquid composite electrocatalysts

The improvement of catalysts for the four-electron oxygen-reduction reaction (ORR; O(2) + 4H(+) + 4e(-) → 2H(2)O) remains a critical challenge for fuel cells and other electrochemical-energy technologies. Recent attention in this area has centred on the development of metal alloys with nanostructured compositional gradients (for example, core-shell structure) that exhibit higher activity than supported Pt nanoparticles (Pt-C; refs 1-7). For instance, with a Pt outer surface and Ni-rich second atomic layer, Pt(3)Ni(111) is one of the most active surfaces for the ORR (ref. 8), owing to a shift in the d-band centre of the surface Pt atoms that results in a weakened interaction between Pt and intermediate oxide species, freeing more active sites for O(2) adsorption. However, enhancements due solely to alloy structure and composition may not be sufficient to reduce the mass activity enough to satisfy the requirements for fuel-cell commercialization, especially as the high activity of particular crystal surface facets may not easily translate to polyfaceted particles. Here we show that a tailored geometric and chemical materials architecture can further improve ORR catalysis by demonstrating that a composite nanoporous Ni-Pt alloy impregnated with a hydrophobic, high-oxygen-solubility and protic ionic liquid has extremely high mass activity. The results are consistent with an engineered chemical bias within a catalytically active nanoporous framework that pushes the ORR towards completion.

A serum-resistant polyamidoamine-based polypeptide dendrimer for gene transfection

A serum tolerant polycation gene vector, G(2) PAMAM-PGlu-G(1) PAMAMs (ALA), was designed, synthesized, characterized and evaluated. A honeycomb-like molecular structure model for mechanistic explanation of ALA was postulated and discussed. Designed as a star-shaped polyamidoamine (PAMAM)-based polypeptide dendrimer through peptide bond linkages, ALA was with non-toxic low generation G(2) PAMAM (G(2)) as its central core, polyglutamate (PGlu)s as its star-shaped backbone branches and G(1) PAMAM (G(1))s as its branch grafts and peripheral terminals. IR, (1)H NMR demonstrated its successful combination. As a gene carrier, ALA exhibited good DNA binding and condensation capacity with particle size (approximately 87 nm for N/P 40, approximately 170 nm for N/P 30) and ζ-potential (approximately 16 mV for N/P 30-40), negligible cytotoxicity, exciting serum tolerant capacity and significant serum-promoted (serum-containing 56.6%>serum-free 32.7%), cell line dependent (Hek 293 > Bel 7402 > Hela), incubation period dependent (38 h > 18 h > 12 h > 9 h > 4 h > 2 h > 1 h) and sustained (peak transfection appeared at 30 h incubation) transfection efficiency. The presence of serum had not only no inhibition on, but also prominent promotion to, the transfection activity of ALA. All above features differentiated ALA clearly from most other serum-inhibitive nonviral gene carriers, and proved ALA the promising and challenging potential efficient gene vector for practical clinical application.

Atomic-scale heterogeneity of a multicomponent bulk metallic glass with excellent glass forming ability

We report the atomic structure of a multicomponent Cu45Zr45Ag10 bulk metallic glass investigated by state-of-the-art experimental and computational techniques. In comparison with a binary Cu50Zr50 metallic glass, Zr-rich interpenetrating clusters centered by paired and stringed Ag atoms and Cu-rich icosahedra are widely observed in the ternary Cu45Zr45Ag10 alloy. The atomic-scale heterogeneity caused by chemical short- and medium-range order is found to play a key role in stabilizing the liquid phase and in improving the glass forming ability of the multicomponent alloy.

Thermodynamic origins of shear band formation and the universal scaling law of metallic glass strength

We report a universal scaling law, tau_{y} = 3R(T_{g}-RT)/V, that uncovers an inherent relationship of the yield strength tau_{y} with the glass transition temperature T_{g} and molar volume V of metallic glasses. This equation is derived from fundamental thermodynamics and validated by various metallic glasses with well-defined yielding. The linearity between tau_{y} and T_{g} demonstrates the intrinsic correlation between yielding and glass-liquid transition, which contributes to the basic understanding of the strength and deformation of glassy alloys.

Formation of an intermediate compound with a B12H12 cluster: experimental and theoretical studies on magnesium borohydride Mg(BH4)2

Experimental and theoretical studies on Mg(BH4)2 were carried out from the viewpoint of the formation of the intermediate compound MgB12H12 with B12H12 cluster. The full dehydriding and partial rehydriding reactions of Mg(BH4)2 occurred according to the following multistep reaction: Mg(BH4)2 -->1/6MgB12H12 + 5/6MgH2 + 13/6H2 <--> MgH2 + 2B + 3H2 <--> Mg + 2B + 4H2. The dehydriding reaction of Mg(BH4)2 starts at approximately 520 K, and 14.4 mass% of hydrogen is released upon heating to 800 K. Furthermore, 6.1 mass% of hydrogen can be rehydrided through the formation of MgB12H12. The mechanism for the formation of MgB12H12 under the present rehydriding condition is also discussed.

Depressurization amorphization of single-crystal boron carbide

We report depressurization amorphization of single-crystal boron carbide (B4C) investigated by in situ high-pressure Raman spectroscopy. It was found that localized amorphization of B4C takes place during unloading from high pressures, and nonhydrostatic stresses play a critical role in the high-pressure phase transition. First-principles molecular dynamics simulations reveal that the depressurization amorphization results from pressure-induced irreversible bending of C-B-C atomic chains cross-linking 12 atom icosahedra at the rhombohedral vertices.

Unusually small electrical resistance of three-dimensional nanoporous gold in external magnetic fields

We report the electric conductivity of three-dimensional (3D) nanoporous gold at low temperatures and in strong magnetic fields. It was found that topologically disordered 3D nanoporosity leads to extremely low magnetoresistance and anomalous temperature dependence as the characteristic length of nanoporous gold is tuned to be approximately 14 nm. This study underscores the importance of 3D topology of a nanostructure on electronic transport properties and has implications in manipulating electron transport by tailoring 3D nanostructures.

Metallic glass nanowire

Metallic glass nanowires were spontaneously created on the fracture surfaces that were produced by a conventional mechanical test. The presence of the nanowires is directly related to the one-dimensional meniscus configuration with a small viscosity at high temperatures and to the wide supercooled liquid region of the metallic glass. The electron microscopic observations demonstrate the diameters, the lengths, and the amorphous structural states, and the energy dispersive X-ray reveals the chemical components. In addition, we found that round ridges are constructed from nanotubes. The finding of amorphous nanostructures not only provides a fundamental understanding of fracture processes but also gives a new insight into nanoengineering constructions.

Dynamic plasticity and failure of high-purity alumina under shock loading

Most high-performance ceramics subjected to shock loading can withstand high failure strength and exhibit significant inelastic strain that cannot be achieved under conventional loading conditions. The transition point from elastic to inelastic response prior to failure during shock loading, known as the Hugoniot elastic limit (HEL), has been widely used as an important parameter in the characterization of the dynamic mechanical properties of ceramics. Nevertheless, the underlying micromechanisms that control HEL have been debated for many years. Here we show high-resolution electron microscopy of high-purity alumina, soft-recovered from shock-loading experiments. The change of deformation behaviour from dislocation activity in the vicinity of grain boundaries to deformation twinning has been observed as the impact pressures increase from below, to above HEL. The evolution of deformation modes leads to the conversion of material failure from an intergranular mode to transgranular cleavage, in which twinning interfaces serve as the preferred cleavage planes.

Reduction of wild type p53 function confers a hormone resistant phenotype on LNCaP prostate cancer cells

BACKGROUND

The protein encoded by the p53 gene is required for some forms of apoptosis and loss or mutations in this gene are found with increased frequency in advanced and hormone resistant human prostate cancers. In order to better appreciate whether reduction of wildtype p53 function in prostate cancer cells might contribute to the development of therapeutic-resistance by these cells, we created stable variants of the androgen-responsive, wild type p53-expressing human prostate cancer cell line, LNCaP, by transfection with expression vectors designed to reduce expression or function of wildtype p53 in them. These cells were then tested for their ability to form tumors in castrated male nude mice.

METHODS

A conditional eukaryotic expression vector (under tetracycline regulation) expressing antisense p53 cDNA was constructed and either directly transfected into LNCaP cells or tranduced into these cells using recombinant retroviruses containing the vector. Stably transfected/transduced cells (LNCaP/Asp53) were evaluated by Western blot analysis for the ability of doxycycline to reduce p53 protein expression and for their ability to form tumors in castrated male nude mice treated or untreated with doxycycline. Additionally, we derived an LNCaP subline (LNCaP/DD) stably expressing a dominant-negative form of p53 and tested these cells for their ability to form tumors in castrated male nude mice.

RESULTS

LNCaP/Asp53 cells showed reduced expression of p53 protein when cultured in a medium containing doxycycline and tested sublines were able to efficiently form tumors in castrated male nude mice only when the mice were treated with doxycycline. LNCaP/DD cells were readily able to form tumors in castrated male nude mice whereas parental LNCaP cells or control-transfected LNCaP cells were not.

CONCLUSION

Loss of wildtype p53 function can contribute to the phenotype of hormone resistance of prostate cancer cells.

Vascular endothelial growth factor-A expression in the rat ventral prostate gland and the early effects of castration

BACKGROUND

Blood flow to the rat ventral prostate gland is drastically reduced during the very early period after castration, and this reduction coincides with the appearance of striking degenerative changes within the prostatic vascular system. These early effects on the prostate vascular system are likely to be important for the subsequent regression of the ventral prostate that occurs in response to castration. Since the endothelial cells of the ventral prostate do not express androgen receptor protein (AR), we proposed that these early effects might be indirectly mediated by changes in the local expression of vascular regulatory factors. In order to evaluate whether vascular endothelial growth factor-A (VEGF-A) might be among the primary mediators of these effects, we measured expression of VEGF-A mRNA and protein in the rat ventral prostate gland prior to and within the first 3 days after castration.

METHODS

Ventral prostate tissues were obtained from control (unoperated) rats, sham-operated rats, or rats at sequential daily intervals (1-3 days) after castration. A quantitative RNase protection assay and a comparative RT-PCR assay were used to evaluate the extent to which the expression of VEGF-A mRNA in the ventral prostate was affected by castration. In situ immunohistochemistry, using an anti-VEGF-A antibody, was performed to localize VEGF-A protein in the various cells of the tissue. Western blot analysis and a quantitative ELISA assay using anti-VEGF-A antibodies were performed to determine how VEGF-A protein expression in the rat ventral prostate was affected by castration.

RESULTS

Results of VEGF-A mRNA analysis in the rat ventral prostate gland during the first 3 days after castration showed a biphasic change characterized by a transient reduction of VEGF-A mRNA expression (by approximately 50%) on the second day after castration that was restored to higher than control levels by the third day after castration. Immunohistochemical analysis for VEGF-A in control and castrated ventral prostates showed that the prostatic epithelial and smooth muscle cells were the major source of VEGF-A expression in this tissue. Quantitative analysis of VEGF-A protein expression by Western blot and ELISA methods confirmed a biphasic change in the expression of the polypeptide that correlated well with the results of the mRNA analyses.

CONCLUSIONS

VEGF-A expression in the ventral prostate gland of the Sprague-Dawley rat is downregulated on the second day after castration but returns to control levels by the third day after castration. Since critical changes in the ventral prostate vascular system are already evident by 1 day after castration, we believe that these findings indicate that VEGF-A is not likely to be the critical or sole mediator of the early effects of castration on the vascular system of the rat ventral prostate gland.

Apoptotic conversion: evidence for exchange of genetic information between prostate cancer cells mediated by apoptosis

Changes in the outer membrane of apoptotic cells can induce neighboring cells to become phagocytic. Using genetically marked prostate cancer cell lines, we explored the possibility that genetic information might be transferred from an apoptotic cell to a phagocytic neighbor. Neomycin-resistant LNCaP cells that overexpress bcl-2 (LNCaP(bcl-2/neo-r)) were cocultured with hygromycin-resistant LNCaP cells (LNCaP(hygr-r)). The cocultures were then transiently exposed to serum starvation to induce apoptosis of LNCaP(hygr-r) cells. Surviving cells were then coselected in medium containing both antibiotics. Whereas monocultures of LNCaP(bcl-2/neo-r) or LNCaP(hygr-r) treated this way yielded no colonies, cocultures yielded dual-antibiotic-resistant clones at a frequency of approximately 1 in 10(5). Pre-exposure to an apoptotic agent was required; cocultures not exposed to serum starvation yielded no dual-selectable colonies. Analysis of DNA extracted from a dual-resistant clone demonstrated that the restriction endonuclease pattern of the neo-r gene was unaltered when compared with the parental LNCaP(bcl-2/neo-r). However the hygr-r gene demonstrated an altered restriction endonuclease pattern in the dual-resistant derivative compared with the parental LNCaP(hygr-r) cell line. This is evidence that genetic information can be transferred from one prostate cancer cell to another through the process of apoptosis, and we term this form of genetic transfer "apoptotic conversion."

Transdifferentiation of prostate cancer cells to a neuroendocrine cell phenotype in vitro and in vivo

PURPOSE

To better understand the source of neuroendocrine cells associated with human prostate cancer progression, we studied the ability of a cultured prostate cancer cell line, LNCaP, to transdifferentiate into neuroendocrine-like cells in vitro and in vivo.

MATERIALS AND METHODS

Cyclic AMP concentrations were measured in extracts of LNCaP cells cultured in the presence of normal or hormone-deficient medium (containing charcoal-stripped serum) with the use of an immunoassay. Quantitative RT-PCR procedures were used to determine whether hormone depletion affects TGF-beta2 mRNA expression. Western blotting procedures (for neuron specific enolase [NSE]) were used to determine whether TGF-beta2 supplementation or antibody neutralization might affect the ability of cultured LNCaP cells to transdifferentiate to neuroendocrine-like cells. Finally, tumors formed from LNCaP cells xenografted into male nude mice were evaluated for the presence of neuroendocrine cells (prior and subsequent to castration of the host mouse) using an immunohistochemical stain for chromogranin A.

RESULTS

LNCaP cells cultured in a hormone-deficient medium have a mean 9-fold increase in cyclic AMP (p = 0.02) and a significant decline in the expression of TGF-beta2 mRNA when compared with cells grown in normal medium. Supplementation or depletion of TGF-beta2 did not affect the neuroendocrine conversion of LNCaP cells as assessed by NSE expression patterns. LNCaP tumors growing in castrated male nude mice were found to have significantly increased numbers of chromogranin A positive neuroendocrine cells (46/high powered field) when compared with tumors growing in intact male mice (3/high powered field) (p = 0.0038).

CONCLUSIONS

Exposure of LNCaP cells to a hormone deficient medium drastically increased cyclic AMP production and this may identify the biochemical pathway through which hormone depletion induces a neuroendocrine conversion of prostate cancer cells. Hormone depletion also reduced TGF-beta2 mRNA expression and this finding was consistent with our inability to demonstrate any effect of TGF-beta2 on neuroendocrine conversion in vitro. Finally, our demonstration of increased neuroendocrine cells found in LNCaP tumors growing in castrated immunodeficient mice suggests that the neuroendocrine cells associated with advanced human prostate tumors in vivo, arise from prostate cancer cells through the transdifferentiation process.

Expression of VEGF splice variants 144/145 and 205/206 in adult male tissues

Currently, at least five different mRNA species encoding vascular endothelial growth factor-A (VEGF-A) have been characterized. These variants result from alternative splicing of the VEGF-A transcript and encode human isoforms of VEGF protein of 121, 145, 165, 189, and 206 amino acids. In the rat, a similar profile of VEGF-A splice variants has been described, each encoding one fewer amino acid than the human species. Studies of mammalian tissues have shown that these mRNA isoforms vary in abundance. Whereas VEGF 188/189, 164/165, and 120/121 (rat/human, respectively) are the predominant forms expressed in most tissues and cells examined, VEGF 144/145 and 205/206 are rare variants. Previously, VEGF 144/145 had been detected only in placental and uterine tissues and endometrial carcinoma cell lines, whereas VEGF 205/206 was detected only in fetal liver and placenta. Using an RT-PCR technique, cDNA cloning, and sequencing, we have detected and confirmed the presence of mRNA encoding VEGF 144/145 and 205/206 in both adult rat lung and penis. Therefore, these low-abundance VEGF splice variants have a more diverse expression pattern than originally predicted.

Castration induces acute vasoconstriction of blood vessels in the rat prostate concomitant with a reduction of prostatic nitric oxide synthase activity

PURPOSE

Previous studies demonstrating a rapid and drastic reduction of blood flow to the rat prostate gland resulting from castration caused us to consider the influence of castration on the state of vascular constriction and on the activity of the vascular tone-regulating factors (nitric oxide synthase and cyclic GMP) in the rat prostate.

MATERIALS AND METHODS

Sections of ventral prostate glands obtained from intact and castrated rats were analyzed for the mean areas within smooth muscle-coated blood vessels using a computerized microscopic image analysis system. Nitric oxide synthase (NOS) levels were measured in prostatic extracts from unoperated or castrated rats using an enzyme assay system that measures conversion of 3H-L-arginine to citruline. Cyclic GMP levels were measured in prostatic extracts from unoperated or castrated rats using a competitive radioimmunoassay system.

RESULTS

The mean area within ventral prostate smooth muscle-coated blood vessels was reduced 39% at 24 hours after castration (p = 0.039) and 47.7% at 48 hours after castration (p = 0.039). NOS activity measured in prostatic extracts was reduced 38% at 24 hours (p = 0.0012) and 51.6% at 36 hours after castration (p = 0.0001) compared with the control group of noncastrated rats. Finally, prostatic cGMP levels were reduced 55.8% (p = 0.0018) at 36 hours after castration when compared with controls rats.

CONCLUSION

Within 24 hours after castration, the lumenal areas of smooth muscle-coated blood vessels in the rat prostate gland were found to be significantly reduced. This vasoconstriction was associated with a significant reduction of prostatic NOS activity as well as a reduction in the prostatic levels of the NOS co-factor, cGMP. Thus, acute vasoconstriction is a prominent early event associated with rat prostate regression in response to castration and likely contributes to the regression of the tissue.

Fas antigen/CD-95 upregulation and activation during castration-induced regression of the rat ventral prostate gland

BACKGROUND

Fas antigen/CD 95 is a 45-kDa transmembrane protein that can initiate intracellular signaling pathways, leading to apoptosis when it is clustered on the cell surface. A recent report claiming that the ventral prostate glands of lpr -/- mutant mice (lacking functional fas antigen) do not regress following castration prompted our analysis of the regressing rat ventral prostate gland for evidence that fas antigen might participate in the molecular process leading to prostate cell apoptosis after castration.

METHODS

An RNase protection assay and Western blotting analysis were used to quantify fas antigen mRNA and protein expression in the regressing rat ventral prostate gland. Immunoprecipitates of fas antigen from membrane preparations made from control or castrated rat prostates were analyzed for coprecipitation of FADD and RIP proteins to assess the activation state of the fas antigen before and after castration. Finally, prostate tissues obtained from two different strains of lpr -/- mutant mice were analyzed for induced apoptosis after castration by the TUNEL staining method.

RESULTS

Rat ventral prostate gland fas antigen mRNA and protein expression was upregulated approximately 3-5-fold in the 3-day castrated rat as compared to hormonally intact rats. Immunoprecipitates of fas antigen from membranes of ventral prostates from castrated rats contained significantly increased amounts of both FADD and RIP proteins when compared to those of intact or control operated rats. However, counts of TUNEL-labeled cells in the ventral prostate glands of castrated lpr -/- mice were not significantly different from those in castrated, genetically normal controls. Likewise, the morphology of apoptotic bodies formed in the prostates of castrated lpr -/- mice was indistinguishable from that in control animals.

CONCLUSIONS

Fas antigen/CD-95, a protein that is involved in some forms of apoptosis, is upregulated during regression of the rat ventral prostate gland and becomes functionally "activated." However, our inability to distinguish any difference in the apoptosis rate or in the morphology of the apoptotic bodies formed in response to castration between lpr -/- mice and genetically normal controls indicates that, contrary to the prior report, functional fas protein is not required for castration-induced prostate cell apoptosis.

Expression of messenger ribonucleic acid splice variants for vascular endothelial growth factor in the penis of adult rats and humans

Erectile dysfunction is often associated with problems in vascular perfusion to the erectile components of the penis. In order to better understand the factors that control vascular formation and perfusion in the erectile tissues of the penis, we have begun to characterize the expression of vascular endothelial growth factor (VEGF) in penis tissues. VEGF is one of several polypeptides that have significant angiogenic activity in vitro and in vivo. Extensive characterization of the VEGF gene and its products has shown that several different mature mRNA transcripts exist, originating from alternative splicing of the basic VEGF transcript. These variant transcripts can encode peptides with different biological activities. Penile tissue was obtained from adult rats and from human patients undergoing penile prosthesis implantation. Analysis of the forms of VEGF transcripts was performed using a reverse transcription-polymerase chain reaction technique with primer pairs derived from the first and eighth exon of the VEGF gene. The expression levels of the various isoforms in the rat penis were then quantified using RNase protection assays. Four previously described splice variants of VEGF mRNA (VEGF 120, 144, 164, 188) were detected in rat and human penile tissues. In contrast to what is seen in the rat lung, where the most abundant form of VEGF mRNA is the 188 splice isoform, VEGF 164 is the most abundant transcript detected in the penis. Finally, sequence analysis of numerous VEGF cDNA clones obtained from the rat penis demonstrated the presence of a previously undescribed VEGF splice variant that could give rise to a protein of 110 amino acid residues (VEGF 110, GenBank accession no. AF080594). In summary, a number of VEGF mRNA isoforms are expressed in the rat and human penis, with the splice variant encoding a 164-amino acid protein present in greatest abundance. This study is a prelude to attempts to genetically manipulate VEGF expression in the penis as a therapy for erectile dysfunction.

An elevated bax/bcl-2 ratio corresponds with the onset of prostate epithelial cell apoptosis

The prostate gland in adult male rats is highly dependent on androgenic steroids. Castration initiates the regression of this tissue through a process involving the loss of the vast majority of cells by means of apoptosis. We studied this well characterized in vivo model of apoptosis to evaluate how the expression of two particular gene products, bcl-2 and bax, known to be important for the regulation of apoptosis were affected by castration. An RNase protection assay designed to quantify the levels of bax mRNA showed that this transcript was transiently elevated after castration, reaching a peak in expression at 3 days and declining thereafter. In contrast, bcl-2 mRNA expression was continuously elevated over a period of up to 7 days after castration. The distinct changes in the expression of the mRNAs encoding these two genes were confirmed by an in situ hybridization analysis of regressing rat ventral prostate tissues. The elevation in mRNAs were apparently restricted to the secretory epithelial cells of the gland, the cellular compartment of the tissue most affected by castration. Finally, SDS - PAGE/Western blot analysis of bax and bcl-2 protein expression in the regressing rat prostate gland with bax and bcl-2-specific antibodies showed that the changes in the bax and bcl-2 protein levels were similar and consistent to that found for the mRNAs. In summary, the expression of both bax and bcl-2 gene products are uniquely modulated during castration-induced regression of the rat ventral prostate gland. The changes we observed identify a transient but marked increase in the bax/bcl-2 expression ratio of the tissue that peaks on the second and third days after castration, coinciding with the peak periods of prostate cell apoptosis. These data support previous studies done on in vitro systems wherein it was shown that the bax/bcl-2 ratio determines the apoptotic potential of a cell.

Abnormal prostate development in C3(1)-bcl-2 transgenic mice

BACKGROUND

Recent hypotheses to explain the etiology of abnormal growth associated with prostate disease have invoked perturbations in the rate of apoptosis as an important contributor to the onset and progression of these diseases. For this reason, the apoptosis suppressing oncoprotein bcl-2 has come under scrutiny with regards to its role in prostate diseases. In order to evaluate the role of bcl-2 in human prostate disease and to develop an animal model to test anti-bcl-2 therapies, we generated transgenic mice in which bcl-2 expression is targeted to the mouse prostate gland.

METHODS

Mouse embryos were microinjected with recombinant DNA constructed by fusing a modified rat C3(1) promotor element to cDNA encoding human bcl-2. Presence of the C3(1)-bcl-2 transgene in progeny was identified by Southern blot and polymerase chain reaction (PCR) analysis. RNase protection assays were used to analyze RNA from 15 organs of these mice. Western blot assays and immunohistochemical staining were used to confirm the tissue-specific protein expression of human bcl-2 and its cellular localization.

RESULTS

Three lines of C3(1)-bcl-2 transgenic mice were established. Founder mice carried 2-20 copies of the transgene. Expression of human bcl-2 from the transgene was limited to the prostate gland and testis of males as well as the uterus of females. In the prostate gland, human bcl-2 protein was found only in prostatic epithelial cells. Microscopic analysis of prostate glands from individual males (three lines) showed that these glands were often abnormal, with increased accumulation of cells in the prostatic stroma as well as the epithelium.

CONCLUSIONS

These transgenic mice appear to provide a novel animal model for studying neoplastic development of the prostate, with particular emphasis on the bcl-2 protein and the role of apoptosis regulation in such development.

Expression of the tumor-associated gene MN: a potential biomarker for human renal cell carcinoma

MN is a novel cell surface antigen originally detected in human HeLa cells. Although it is also expressed in normal gastric mucosa, this antigen was previously found to be expressed in cells with a malignant phenotype in certain tissues of the female genital tract (cervix and ovary). Using an oligonucleotide primer set specific for MN-complimentary DNA, we performed reverse transcription-PCR assays on RNAs extracted from human cell lines and tissues to evaluate whether this marker might be expressed at other sites. RNA libraries extracted from normal human heart, lung, kidney, prostate, peripheral blood, brain, placenta, and muscle were negative for MN expression. RNAs extracted from liver and pancreatic tissue were positive for MN expression. Three of six renal cancer cell lines tested revealed MN expression. In addition, 12 of 17 samples of human renal cell carcinoma tissue tested positive for MN, all 12 of which were clear cell adenocarcinomas. This survey identified a unique association of MN expression with renal cell cancers, especially those of the clear cell variety, suggesting that MN is a potential marker for the diagnosis, staging, and therapeutic monitoring of renal cell carcinoma in humans.

Animal models of bladder outlet obstruction and molecular insights into the basis for the development of bladder dysfunction

In humans, chronic bladder outlet obstruction resulting from benign prostatic hypertrophy (BPH) can induce severe and irreversible upper urinary tract changes, especially in the bladder. BPH can be mimicked in rabbits by artificially creating a partial obstruction of the bladder outlet. The structural and functional changes initiated eventually elicit a pathology and symptomology similar to human BPH. The rabbit bladder responds to partial outlet obstruction in three characteristic stages: hypertrophy, compensation and decompensation Basic fibroblast growth factor, epidermal growth factor and transforming growth factor-beta appear to be involved in the hypertrophy phase. During this initial phase normal bladder function is maintained but in the later phases, it is drastically impaired. We propose that the various stages of bladder remodelling subsequent to partial outlet obstruction are essentially driven by reduction in blood flow to the bladder (ischaemia). Initially this ischaemia might stimulate a compensatory response enabling the bladder to deal with the stress outlet obstruction. However, the long-term reduction in blood flow resulting from cyclical filling of the obstructed bladder, ultimately induces the degenerative changes that impede bladder function. These findings have important implications for the development of novel therapies to prevent or reverse bladder dysfunction resulting from BPH.

[Acute uremic pericarditis presented as cardiac tamponade with acute ischemic hepatitis: a case report]

Pericarditis is a frequent and serious complication of chronic uremia. The uremic pericarditis can get much improvement by aggressive heparin-free hemodialysis therapy. However, the presenting symptoms and signs are too nonspecific to identify at early stage. Cardiac tamponade is the late and fatal complication, and need the immediate & adequate management. A 35-year-old female patient suffered from nausea, vomiting and right upper quadrant dull pain in November 1993, and was admitted to a local hospital. Uremia (BUN: 210 mg/dl, serum Cr.: 13.2 mg/dl) and abnormal liver function (SGOT: 330 IU/L, SGPT: 449 IU/L) were found, then she received regular hemodialysis therapy. About 10 days later, acute exacerbation of liver function (SGOT: 2,488 IU/L, SGPT: 1,048 IU/L), consciousness disturbance and hypotension occurred during hemodialysis. She was referred to our ER immediately. At ER, she had been on comatous, shock state with pulseless electric activity. After resuscitation and serial evaluation, cardiac tamponade was diagnosed. Emergent pericardiocentesis and then bilateral partial pericardiectomy were done about 2 hours later. The pericardial effusion was bloody without evidence of malignancy, bacterial or TB infection. The pathology of pericardium revealed chronic inflammation only. HBsAg, Anti-HCV Ab, and anti-HAV IgM were undetectable. So the etiology of acute hepatitis was diagnosed as ischemic hepatitis. Her general condition and vital sign became stable thereafter. The liver function also improved rapidly. She was discharged one month later and received maintainance hemodialysis therapy and no evidence of recurrence till now.

Genetic and cellular response to unilateral ischemia of the rabbit urinary bladder

PURPOSE

Previous studies have demonstrated that partial outlet obstruction and acute overdistension of the rabbit bladder rapidly stimulate the activation of similar patterns of gene expression. Since bladder overdistension has been shown to reduce the blood flow of the bladder and since unilateral ischemia of rabbit bladder has been found to induce similar physiologic and histologic changes to the bladder as found in association with partial outlet obstruction, we tested whether experimental ischemia of the rabbit bladder could induce the same molecular response.

MATERIAL AND METHODS

Unilateral ischemia was created by surgically ligating the major arteries entering the rabbit bladder to one side. Bladders were recovered from control rabbits and from rabbits at 1 hour, 8 hours, 1, 3, or 7 days after unilateral ischemia and were divided into ischemic and nonischemic portions. These tissues were used for in vitro 35S-methionine and 3H-thymidine incorporation assays. Ribonucleic acids extracted from these tissues were examined by Northern blot assay for the expression of a number of different mRNA transcripts.

RESULTS

1) Bladder DNA synthesis was elevated 4-fold at 24 hours after ischemia; 2) protein synthesis was increased 2-fold at 8 and 24 hours after ischemia; 3) early response genes (c-fos and c-jun) mRNAs were induced by 1 hour of ischemia; hsp-70 mRNA was highly induced by 8 hours of ischemia, and bFGF mRNA was elevated 3- to 5-fold by 8 hours of ischemia.

CONCLUSION

The early molecular response of rabbit bladder to ischemia is similar to responses observed in bladder overdistension or partial outlet obstruction.

Overexpression of bcl-2 protects prostate cancer cells from apoptosis in vitro and confers resistance to androgen depletion in vivo

Normal (nonneoplastic) human prostatic secretory epithelial cells do not express the bcl-2 protein. However, a recent immunohistochemical survey of neoplastic human prostate tissues showed that a fraction of primary untreated prostate adenocarcinoma cells expressed this apoptosis-suppressing oncoprotein at significant levels (Colombel et al., Am. J. Pathol., 143: 390-400, 1993). Additionally, a number of hormone-refractory prostatic adenocarcinomas obtained from hormonally-treated patients (subsequent to surgical or drug castration therapy) were examined and were found to be uniform in their elevated expression of bcl-2 oncoprotein. The results of this preliminary survey imply that bcl-2 expression distinguishes a subgroup of primary human prostate cancers and that the expression of this protein might be a factor enabling prostate cancer cells to survive in an androgen-deprived environment. The current study was undertaken to determine the degree to which overexpression of bcl-2 can protect human prostate cancer cells from apoptotic stimuli in vitro and in vivo. Human prostate cancer cells (LNCaP) were transfected with a neomycin-selectable eucaryotic expression vector containing cDNA encoding human bcl-2. Transfected clonal variants that express bcl-2 protein (LNCaP/bcl-2) were unaltered with regard to their basal growth rate in 10% serum-containing medium, or with regard to their expression of the differentiated human prostate cell gene products prostate-specific antigen or androgen receptor protein. The bcl-2-transfected clones were altered, however, with regard to their growth rate in charcoal-stripped serum lacking dihydrotestosterone. Additionally, in contrast to the parental or control-transfected cell lines, LNCaP/bcl-2 cells were highly resistant to a variety of apoptotic stimuli in vitro including serum starvation and 10 nM phorbol ester (phorbol 12-myristate 13-acetate) supplementation of the medium. Lastly, the overexpression of bcl-2 by these prostate cancer cells altered their tumorigenic potential in a nude mouse assay. s.c. injections of 10(6) LNCaP/bcl-2 cells into male nude mice resulted in earlier and larger tumor formation compared to an equivalent injection of parental or control-transfected LNCaP cells. When these variant cell lines were injected into castrated male nude mice, only the LNCaP/bcl-2-transformed cells gave rise to tumors. Moreover, LNCaP/bcl-2 tumors grown in intact male nude mice were refractory to the growth-inhibiting effects of castration demonstrated by parental LNCaP cells. Data obtained in this study demonstrate that the bcl-2 oncoprotein can protect prostate cancer cells from apoptotic stimuli in vitro and suggest that such protection correlates with the ability to form hormone-refractory prostate tumors in vivo.

Bladder function in experimental outlet obstruction: pharmacologic responses to alterations in innervation, energetics, calcium mobilization, and genetics

The two functions of the urinary bladder is to store urine at low intravesical pressures, and to periodically expel the urine through a coordinated contraction of the bladder and relaxation of the urethra. To a large extent, urinary bladder function depends upon the underlying structure of the organ as a whole, particularly on the inter-relationships among the smooth muscle, connective tissue, and neuronal elements. An alteration in the ratio of connective tissue to smooth muscle, for example, can significantly alter compliance and functional capacity, structurally impairing the bladder's ability to empty efficiently and fully. Thus, a change in structural compartmentation can affect bladder function independent of autonomic receptor density, response to receptor stimulation, and the contractile capabilities of the smooth muscle elements. Similarly, a selective alteration in either the afferent or efferent innervation of the bladder or urethra can induce significant alterations in the structural interrelationships between smooth muscle and connective elements. In addition, the bladder responds rapidly to alterations in urine volume and urethral resistance with marked changes in bladder and urethral structure and function, and these changes are under the controls of specific genes that are known to control cellular growth, hypertrophy, and hyperplasia. A knowledge of the mechanisms that control the response to specific forms of stress may lead to novel therapies for specific disease states.

Peptide growth factors in normal and hypertrophied bladder

The bladder is a dynamic organ that responds to the stress of outlet obstruction by rapidly increasing in mass and cellular content to compensate for increased urethral resistance. If the outlet obstruction is released prior to decompensation, the hypertrophied bladder will shrink, returning to normal size and cellularity. However, with chronic obstruction the bladder will continue to increase in mass, developing drastic alterations in the amount and composition of the extracellular matrix and, ultimately, losing the ability to function. The extensive tissue remodeling associated with each of these changes requires different bladder components to undergo cellular proliferation, cellular hypertrophy, and even programmed cell death (apoptosis). Each of these cellular processes is known to be regulated by various peptides that are referred to as growth factors. Herein we provide an overview of the growth factors that are known to influence the bladder in addition to a variety of experimental animal studies that putatively identify a role of four particular growth factors [basic fibroblast growth factor (bFGF), transforming growth factor-beta (TGF-beta), nerve growth factor (NGF), and epidermal growth factor (EGF)] in the obstructive bladder response.

Changes in lumbar disc angles of Chinese subjects from upright to flexion

STUDY DESIGN

This study analyzed the sizes and angles of vertebrae and discs in Chinese subjects. Lateral lumbar spine radiograph films were taken of subjects in upright and 60 degrees flexion positions to evaluate disc height and angle changes.

OBJECTIVES

This study sought to gather data regarding the contribution of each segment to lumbar lordotic curvature in upright posture, and angle changes of individual segments from upright to flexion positions.

SUMMARY OF BACKGROUND DATA

Although the dimensions of vertebrae and discs have been measured, little has been done regarding in vivo measurements of lumbar lordotic curvature formation, especially during flexion. In addition, no data are available for the Chinese population.

METHODS

Five men and six women were studied. The lateral lumbar spine radiograph films were taken for upright and 60 degrees flexion positions. The dimensions of vertebral bodies and discs and lumbosacral angle were measured.

RESULTS

The disc heights ranged from 0.7 to 1.2 cm in upright posture. Mean disc angle ranged from 9 degrees to 14 degrees in men and 6 degrees to 13 degrees in women. The lowest three segments (L3-L5) contributed 80% to 90% of the lumbosacral angle (L1-S1), which was approximately 47 degrees. Mean sacral horizontal angle was 35 degrees. From upright to 60 degrees flexion positions, all disc angles decreased uniformly from a total of 53 degrees +/- 6 degrees to 11 degrees +/- 12 degrees in men and 46 degrees +/- 11 degrees to 0 degrees +/- 18 degrees in women.

CONCLUSIONS

The dimensions of lumbar vertebral bodies and discs, in upright and flexion positions, appear to be similar between Chinese and Western populations.

An early molecular response induced by acute overdistension of the rabbit urinary bladder

In the rabbit, partial urinary bladder outlet obstruction rapidly increases bladder mass and alters several parameters of normal bladder function. Previous experiments on this animal model (Buttyan et al. Neurourol. Urodyn. 11:225-238, 1992) had identified an early molecular response to partial outlet obstruction that involved the profound induction of mRNA encoding a heat-shock gene, hsp-70, as well as induced expression of mRNA for basic fibroblast growth factor and certain protooncogenes. Numerous physiological studies of the hypertrophied rabbit bladder indicate that the primary stimulus for bladder growth may be the initial overdistension that occurs as the bladder fills following partial outlet obstruction. The present study was undertaken to determine if the sequence and characteristics of gene activation during the recovery following a brief period of overdistension of the rabbit bladder are comparable with the gene activity previously described in association with partial outlet obstruction. Rabbit bladders were overdistended to 20% above capacity for 1 hr and then relieved. Bladders were recovered from control (untreated) rabbits and from rabbits at 1 hr or at 1, 3 or 5 days following relief of overdistension. RNAs extracted from these tissues were examined by Northern blot assays for a number of different mRNA transcripts previously shown to be altered by partial outlet obstruction. By 1 hr following the relief from acute overdistension, there was already a greater than 10-fold increase in the expression of hsp-70 related transcripts as well as a marked increase in the expression of mRNA encoding bFGF and decreased expression of TGF-beta 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Chloramphenicol acetyltransferase, a cytoplasmic protein is incompatible for export from Bacillus subtilis

Bacillus subtilis cells expressing a hybrid protein (Lvsss-Cat) consisting of the B. amyloliquefaciens levansucrase signal peptide fused to B. pumilus chloramphenicol acetyltransferase (Cat) are unable to export Cat protein into the growth medium. A series of tripartite protein fusions was constructed by inserting various lengths of the Cat sequences between the levansucrase signal peptide and staphylococcal protein A or Escherichia coli alkaline phosphatase. Biochemical characterization of the various Cat protein fusions revealed that multiple regions in the Cat protein were causing the export defect.

Purification and functional characterization of glutamate-1-semialdehyde aminotransferase from Chlamydomonas reinhardtii

The formation of delta-aminolevulinic acid, the first committed precursor of chlorophyll biosynthesis, occurs in the chloroplast of plants and algae by the C5-pathway, a three-step, tRNA-dependent transformation of glutamate. Previously, we reported the purification and characterization of the first two enzymes of this pathway, glutamyl-tRNA synthetase and Glu-tRNA reductase from the green alga Chlamydomonas reinhardtii (Chen, M.-W., Jahn, D., Schön, A., O'Neill, G. P., and Söll, D. (1990) J. Biol. Chem. 265, 4054-4057 and Chen, M.-W., Jahn, D., O'Neill, G. P., and Söll, D. (1990) J. Biol. Chem. 265, 4058-4063). Here we present the purification of the third enzyme of the pathway, the glutamate-1-semialdehyde aminotransferase from C. reinhardtii. The enzyme was purified from the membrane fraction of a whole cell extract employing four different chromatographic separations. The apparent molecular mass of the protein was approximately 43,000 Da as analyzed by denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis, by nondenaturing rate zonal sedimentation on glycerol gradients, and by gel filtration. By these criteria, the enzyme in its active form is a monomer of 43,000 Da. In the presence of pyridoxal 5'-phosphate, purified glutamate-1-semialdehyde aminotransferase converts synthetic glutamate 1-semialdehyde to delta-aminolevulinic acid. The enzyme is inhibited by gabaculine and aminooxyacetate, both typical inhibitors of aminotransferases. The purified glutamate-1-semialdehyde aminotransferase successfully reconstitutes the whole C5-pathway in vitro from glutamate in the presence of purified glutamyl-tRNA synthetase, glutamyl-tRNA reductase, Mg2+, ATP, NADPH, tRNA, and pyridoxal 5'-phosphate.