Expression of constitutively active Notch4 (Int-3) modulates myeloid proliferation and differentiation and promotes expansion of hematopoietic progenitors

The Notch family of transmembrane receptors has been implicated in the regulation of many developmental processes. In this study, we evaluated the role of Notch4 in immature hematopoietic progenitors by inducing, with retroviral transduction, enforced expression of Int-3, the oncogenic and constitutively active form of mouse Notch4. Int-3-transduced human myeloid leukemia (HL-60) cells demonstrated significantly delayed expression of differentiation markers following retinoic acid and 12-0-tetradecanoylphorbol 13-acetate treatment. Furthermore, HL-60 cells expressing Int-3 displayed a slower growth rate than cells infected with void virus, and accumulation in the G0/G1 phases of cell cycle. Transduction with deletion mutants of Int-3 defined the importance of individual domains of the protein (in particular, the ANK domain and the C-terminal domain) in the inhibition of differentiation and growth arrest of HL-60 cells. When mouse bone marrow enriched for stem cells (5-fluorouracil-resistant, lineage negative) was transduced and cultured for two weeks, the Int-3-transduced population displayed a lower expression of differentiation markers and a three- to five-fold higher frequency of colony-forming cells (CFU-GM/BFU-E) than control cultures. These results strongly support the notion that Notch signaling inhibits differentiation and promotes expansion of hematopoietic stem/progenitor cells.

Construction of two BAC libraries from the wild Mexican diploid potato, Solanum pinnatisectum, and the identification of clones near the late blight and Colorado potato beetle resistance loci

To facilitate isolation and characterization of disease and insect resistance genes important to potato, two bacterial artificial chromosome (BAC) libraries were constructed from genomic DNA of the Mexican wild diploid species, Solanum pinnatisectum, which carries high levels of resistance to the most important potato pathogen and pest, the late blight and the Colorado potato beetle (CPB). One of the libraries was constructed from the DNA, partially digested with BamHI, and it consists of 40328 clones with an average insert size of 125 kb. The other library was constructed from the DNA partially digested with EcoRI, and it consists of 17280 clones with an average insert size of 135 kb. The two libraries, together, represent approximately six equivalents of the wild potato haploid genome. Both libraries were evaluated for contamination with organellar DNA sequences and were shown to have a very low percentage (0.65-0.91%) of clones derived from the chloroplast genome. High-density filters, prepared from the two libraries, were screened with ten restriction fragment length polymorphism (RFLP) markers linked to the resistance genes for late blight, CPB, Verticillium wilt and potato cyst nematodes, and the gene Sr1 for the self-incompatibility S-locus. Thirty nine positive clones were identified and at least two positive BAC clones were detected for each RFLP marker. Four markers that are linked to the late blight resistance gene Rpi1 hybridized to 14 BAC clones. Fifteen BAC clones were shown to harbor the PPO (polyphenol oxidase) locus for the CPB resistance by three RFLP probes. Two RFLP markers detected five BAC clones that were linked to the Sr1 gene for self-incompatibility. These results agree with the library's predicted extent of coverage of the potato genome, and indicated that the libraries are useful resources for the molecular isolation of disease and insect resistance genes, as well as other economically important genes in the wild potato species. The development of the two potato BAC libraries provides a starting point, and landmarks for BAC contig construction and chromosome walking towards the map-based cloning of agronomically important target genes in the species.

Retinoic acid fails to reverse emphysema in adult mouse models

BACKGROUND

Previous work has shown that all-trans-retinoic acid reverses elastase induced emphysema in rats. Since there is currently no effective treatment for pulmonary emphysema, the effect of retinoic acid should be further investigated in other adult species. A study was undertaken using two murine models of emphysema to evaluate the effect of retinoic acid.

METHODS

The models used were an elastase induced emphysema model for acute alveolar destruction and a tumour necrosis factor (TNF)-alpha transgenic mouse which exhibits chronic air space enlargement, loss of elastic recoil, increased lung volume, and pulmonary hypertension comparable to human pulmonary emphysema. All-trans-retinoic acid (2 mg/kg) was injected for 12 successive days after the establishment of emphysema. The effects of treatment were evaluated using physiological and morphometric analyses.

RESULTS

In contrast to the rat, administration of all-trans-retinoic acid in these murine models did not improve the emphysema. Moreover, worsening of emphysema was observed in TNF-alpha transgenic mice treated with all-trans-retinoic acid. The level of keratinocyte chemoattractant (KC), a CXC chemokine, in bronchoalveolar lavage fluid was increased in TNF-alpha transgenic mice following retinoic acid treatment. These data raise the possibility that retinoic acid causes deterioration of emphysema by promoting inflammation in this model.

CONCLUSIONS

In these models, retinoic acid did not show positive effects on emphysema. The effect of retinoic acid in the treatment of pulmonary emphysema remains controversial, and further studies are required to determine its physiological effects under a variety of experimental conditions.

Restoration of dystrophin expression in mdx mice by intravascular injection of naked DNA containing full-length dystrophin cDNA

Duchenne muscular dystrophy (DMD) is a lethal, X-linked, recessive disease caused by a defect in the dystrophin gene. No effective therapy is available. Dystrophin gene transfer to skeletal muscle has been proposed as a treatment for DMD. However, successful treatment for DMD requires restoration of dystrophin in the affected muscle fibers to at least 20% of the normal level. Current gene transfer methods such as intramuscular injection of viral vector or naked DNA can only transfect a small area of muscle, and therefore is of little clinical utility. We have developed a semisystemic method for gene transfer into skeletal muscle of mdx mice, an animal model for DMD. Naked DNA was injected through the tail artery or vein of mice, in which the aorta and the vena cava were clamped at the location just below the kidneys. The DNA solution was thus forced into the blood vessels of both legs. Luciferase gene expression was detected in all muscle groups in both legs. The effects of injection speed, injection volume, and ischemia time on gene expression were also optimized. LacZ staining was used to check the spread of gene expression in muscle. Although the percentage of transfected fibers was modest (approximately 10%), beta-galactosidase was found in all muscle groups of both legs. Finally, plasmid DNA encoding full-length dystrophin gene was injected into mdx mice and widespread restoration of dystrophin protein was observed in all muscles of both hind limbs. In conclusion, these results demonstrate that the semisystemic delivery of naked DNA is a potential approach towards the long-term goal of gene therapy for DMD.

Deficiency of the cysteine protease cathepsin S impairs microvessel growth

During angiogenesis, microvascular endothelial cells (ECs) secrete proteinases that permit penetration of the vascular basement membrane as well as the interstitial extracellular matrix. This study tested the hypothesis that cathepsin S (Cat S) contributes to angiogenesis. Treatment of cultured ECs with inflammatory cytokines or angiogenic factors stimulated the expression of Cat S, whereas inhibition of Cat S activity reduced microtubule formation by impairing cell invasion. ECs from Cat S-deficient mice showed reduced collagenolytic activity and impaired invasion of collagens type I and IV. Cat S-deficient mice displayed defective microvessel development during wound repair. This abnormal angiogenesis occurred despite normal vascular endothelial growth factor and basic fibroblast growth factor levels, implying an essential role for extracellular matrix degradation by Cat S during microvessel formation. These results demonstrate a novel function of endothelium-derived Cat S in angiogenesis.

Structure of protein tyrosine phosphatase 1B in complex with inhibitors bearing two phosphotyrosine mimetics

Protein tyrosine phosphatases (PTPases) are signal-transducing enzymes that dephosphorylate intracellular proteins that have phosphorylated tyrosine residues. It has been demonstrated that protein tyrosine phosphatase 1B (PTP1B) is an attractive therapeutic target because of its involvement in regulating insulin sensitivity (Elcheby et al. Science 1999, 283, 1544-1548). The identification of a second binding site in PTP1B (Puius et al., Proc. Natl. Acad. Sci. U.S.A.1997, 94, 13420-13425) suggests a new strategy for inhibitor design, where appropriate compounds may be made to simultaneously occupy both binding sites to gain much higher affinity and selectivity. To test this hypothesis and gain further insights into the structural basis of inhibitor binding, we have determined the crystal structure of PTP1B complexed with two non-peptidyl inhibitors, 4 and 5, both of which contain two aryl difluoromethylenephosphonic acid groups, a nonhydrolyzable phosphate mimetic. The structures were determined and refined to 2.35 and 2.50 A resolution, respectively. Although one of the inhibitors seems to have satisfied the perceived requirement for dual binding, it did not bind both the active site and the adjacent noncatalytic binding site as expected. The second or distal phosphonate group instead extends into the solvent and makes water-mediated interactions with Arg-47. The selectivity of the more potent of these two inhibitors, as well as four other inhibitors bearing two such phosphate mimetics for PTP1B versus seven other PTPases, was examined. In general, selectivity was modest to good when compared to PTPases Cdc25a, PTPmeg-1, PTPbeta, and CD45. However, selectivity was generally poor when compared to other PTPases such as SHP-1, SHP-2, and especially TCPTP, for which almost no selectivity was found. The implications these results have concerning the utility of dual-binding inhibitors are discussed.

BRCA1-induced large-scale chromatin unfolding and allele-specific effects of cancer-predisposing mutations

The breast cancer susceptibility gene BRCA1 encodes a protein that has been implicated in multiple nuclear functions, including transcription and DNA repair. The multifunctional nature of BRCA1 has raised the possibility that the polypeptide may regulate various nuclear processes via a common underlying mechanism such as chromatin remodeling. However, to date, no direct evidence exists in mammalian cells for BRCA1-mediated changes in either local or large-scale chromatin structure. Here we show that targeting BRCA1 to an amplified, lac operator-containing chromosome region in the mammalian genome results in large-scale chromatin decondensation. This unfolding activity is independently conferred by three subdomains within the transactivation domain of BRCA1, namely activation domain 1, and the two BRCA1 COOH terminus (BRCT) repeats. In addition, we demonstrate a similar chromatin unfolding activity associated with the transactivation domains of E2F1 and tumor suppressor p53. However, unlike E2F1 and p53, BRCT-mediated chromatin unfolding is not accompanied by histone hyperacetylation. Cancer-predisposing mutations of BRCA1 display an allele-specific effect on chromatin unfolding: 5' mutations that result in gross truncation of the protein abolish the chromatin unfolding activity, whereas those in the 3' region of the gene markedly enhance this activity. A novel cofactor of BRCA1 (COBRA1) is recruited to the chromosome site by the first BRCT repeat of BRCA1, and is itself sufficient to induce chromatin unfolding. BRCA1 mutations that enhance chromatin unfolding also increase its affinity for, and recruitment of, COBRA1. These results indicate that reorganization of higher levels of chromatin structure is an important regulated step in BRCA1-mediated nuclear functions.

[Production of vitamin C precursor--2-keto-L-gulonic acid from D-sorbitol by mixed culture of microorganisms]

Gluconobacter oxydans SCB329 only produce a little amount of 2-Keto-L-gulonic acid(2-KLG) from D-Sorbitol when growing alone; while Gluconobacter sp. SCB110 can transform D-Sorbitol to L-Sorbose and can not produce 2-KLG. 2-Keto-L-gulonic acid, the precursor of L-Ascorbic acid (Vitamin C) synthesis, was prepared directly with a high efficiency from D-Sorbitol by mixed culture of microorganism, which comprised Gluconobacter sp. SCB110 and Gluconobacter oxydans SCB329. The fermentation product from the mixed culture broth in the D-Sorbotol-containing medium was identified as 2-Keto-L-gulonic acid by HPLC, elementary analysis and infra-red adsorption spectrum.

[Clinical evaluation on second stage reconstruction for laryngostenosis after partial laryngectomy for laryngeal cancer patients]

OBJECTIVE

To present a new method of decannulation for laryngostenosis patients after partial laryngectomy and extended partial laryngectomy, and restoration of the essential functions of larynx and normal neck appearance.

METHODS

Nineteen cases of laryngostenosis after partial laryngectomy and extended partial laryngectomy were treated with second stage reconstruction. The patients had been treated by vertical laryngectomy (6/19) using extended vertical laryngectomy (11/19) and frontolateral laryngectomy (2/19). Among these patients, second stage reconstruction of larynx was performed by using rotary door myocutaneous flap (17/19). Stemohyoideus flap (1/19) and sternocleidomastoid flap (1/19).

RESULTS

Three and five year-survival rates were 91.7% (11/12) and 3/5, respectively. Over-all decannulation rate was 84.2% (16/19), but 94.1% (16/17) in patients with rotary door myocutaneous flap and 0% (0/2) in both patients with sternohyoideus flap and sternocleidomastoid flap. There were 3 decannulation failures (15.8%). All patients resumed acceptable voice, 94.7% (18/19) enjoyed satisfactory phonation, but 5.3% (1/19) showed severe hoarseness. All except 2 patients returned normal swallow function. The latter 2 patients experienced mild abnormal swallow during eating fluid food in early stage of surgery, but had normal swallow function after 1-2 weeks.

CONCLUSION

Functional laryngectomy is a radical operation in selected cases with advanced laryngeal cancer. The second stage reconstruction with bi-pedical rotary door myocutaneous flaps can help decannulation in patients who developed laryngostenosis after partial laryngectomy and extended partial laryngectomy, and restore the essential function of larynx and normal neck appearance.

Inhibition of growth and cell cycle arrest of ARCaP human prostate cancer cells by ectopic expression of ER-alpha

The estrogen receptor-alpha (ER-alpha) is a ligand-dependent transcription factor that regulates the growth, differentiation, and development of hormone-responsive target organs. While ER-alpha has been reported to play critical role in the pathogenesis and prognosis of breast and prostate cancers, its possible functional role in regulating prostate cancer cell growth in a ligand-dependent or -independent manner is poorly understood. We addressed this question by stably transfecting wild type (wt) ER-alpha cDNA into an invasive estrogen receptor-negative human prostate cancer cell line ARCaP. We isolated several clonal lines of transfected cells expressing varying levels of ER-alpha. The ectopic expression of wt ER-a markedly inhibited the growth of ARCaP cells in vitro in an ER-a dose-dependent but ligand-independent manner. Flow cytometric analysis of the wt ER-alpha-transfected ARCaP cells revealed that wt ER-alpha expression arrested cell growth in G1 phase. Our results suggest that ER-alpha may regulate prostate cell growth and participate in the pathogenesis of prostate cancer. ER-alpha may be delivered and expressed ectopically to target prostate cancer progression.

USPIO-enhanced dynamic MRI: evaluation of normal and transplanted rat kidneys

To evaluate first-pass renal perfusion with ultrasmall superparamagnetic iron oxide (USPIO) particles by MRI, 40 normal rats (20 Dark Agouti (DA) rats and 20 Brown Norway (BN) rats) and 16 transplanted rats (12 allografts and four isografts) were studied on day 4 post-transplantation with different USPIO doses (3.0-18.1 mg Fe/kg/body weight). All animals underwent 128 consecutive snapshot fast low-angle shot (FLASH) coronal dynamic studies in 43 s. In the normal rats, a larger maximum signal decrease (MSD) in the cortex and the outer medulla is observed with an increasing dose of USPIO particles (P < 0.01). No significant differences were observed between the right and left kidneys at all doses studied. Higher MSD, time of occurrence of MSD (tMSD), and wash-in slope appear with higher doses of USPIO particles. The dynamic curves for DA rats show similar shapes when compared to those for BN rats. In the transplanted rats, allograft kidneys show lower MSD, longer tMSD, and lower wash-in slope compared to those in the normal kidneys. Isograft kidneys show perfusion patterns similar to those of normal kidneys in the cortex and the outer medulla. Histopathology indicates acute vascular rejection in all allografts and normal kidney architecture in all isografts. The results clearly show good agreement between the renal graft perfusion measurements and histopathological changes associated with rejection. This work also introduces a new signal analysis methodology for the automatic detection of transplanted organ rejection. This method compares the dynamics of the intrarenal signal intensities for native and transplanted kidneys. A quantitative measurement to detect significant differences between these signals was developed, and showed that this technique exhibits good performance in identifying renal rejection.

[Clinical application of TRAFIX internal fixation system in correction of scoliosis]

OBJECTIVE

To evaluate the results of TRAFIX internal fixation system in correction of adolescent scoliosis.

METHODS

From October 1997 to June 1999, 27 patients with idiopathic scoliosis received spinal instrumentation with TRAFIX system. Their average age was 14.2 years (from 11 to 21). Four patients of the 27 underwent anterior release, while 1 patient accepted revision approach. The average follow up time was 26 months (13-37 months).

RESULTS

The measurements for primary coronal deformity before and after surgery were 65 degrees (42 degrees-110 degrees) and 29.2 degrees (3 degrees-64 degrees) respectively. The average curve correction was 55.4%. The average fused segments were 11.5 vertebrae. The distance between the center of apex and C7 plumb line was 52.1 mm before operation (25-94 mm) and 28.5 mm after surgery (4-62 mm).

CONCLUSION

The TRAFIX internal fixation system provides three-dimensional correction with refinement, convenient and reliable fixation.

[Study of calcium buffer in SH-SY5Y cells]

AIM

To study the calcium buffer in SH-SY5Y cells.

METHODS

By using patch clamp technique, measure voltage-gated calcium currents in undifferentiated SH-SY5Y cell line. Then, by using microfluorometric technique, detect the intracellular [Ca2+]i and the dynamic recovery course after high-K+ induced [Ca2+]i elevation.

RESULTS

There are voltage-gated calcium currents in undifferentiated SH-SYSY cell line. When the time intervals between the stimulus are < 150s, the recovery course will be much more deferred because of the saturation of the intracellular calcium buffer; and when the intervals between the stimulus are > 150 s, the buffer will recruit so as to lead to the steadiness state of the recover course.

CONCLUSION

Calcium buffer proteins have an important effect in the course of cellular calcium signal transduction.

Hydrophilic, pro-drug analogues of T138067 are efficacious in controlling tumor growth in vivo and show a decreased ability to cross the blood brain barrier

The novel anticancer compound T138067 is an irreversible inhibitor of tubulin polymerization. Amides 3-6 were synthesized using standard methodologies and determined to be significantly less lipophilic than T138067 based on logP calculations. Tubulin polymerization and [(3)H]-T138067 competition assays revealed that these amides are pro-drugs for parent aniline 2. Amides 3-5 showed no detectable signs of crossing the blood brain barrier, while amide 6 was found in extremely small amounts (12 ng/g of brain tissue). Aniline 2, which was formed in vivo from these amides, was found in significantly smaller amounts (approximately 20 to >5000 times) in the brain than when 2 was administered directly. The in vivo efficacy of amide 6 approached that of T138067 and was better tolerated when administered to athymic nude mice bearing MX-1 human mammary tumor xenografts.

High-resolution crystal structure of apolipoprotein(a) kringle IV type 7: insights into ligand binding

Apolipoprotein(a) [apo(a)] consists of a series of tandemly repeated modules known as kringles that are commonly found in many proteins involved in the fibrinolytic and coagulation cascades, such as plasminogen and thrombin, respectively. Specifically, apo(a) contains multiple tandem repeats of domains similar to plasminogen kringle IV (designated as KIV(1) to KIV(10)) followed by sequences similar to the kringle V and protease domains of plasminogen. The KIV domains of apo(a) differ with respect to their ability to bind lysine or lysine analogs. KIV(10) represents the high-affinity lysine-binding site (LBS) of apo(a); a weak LBS is predicted in each of KIV(5)-KIV(8) and has been directly demonstrated in KIV(7). The present study describes the first crystal structure of apo(a) KIV(7), refined to a resolution of 1.45 A, representing the highest resolution for a kringle structure determined to date. A critical substitution of Tyr-62 in KIV(7) for the corresponding Phe-62 residue in KIV(10), in conjunction with the presence of Arg-35 in KIV(7), results in the formation of a unique network of hydrogen bonds and electrostatic interactions between key LBS residues (Arg-35, Tyr-62, Asp-54) and a peripheral tyrosine residue (Tyr-40). These interactions restrain the flexibility of key LBS residues (Arg-35, Asp-54) and, in turn, reduce their adaptability in accommodating lysine and its analogs. Steric hindrance involving Tyr-62, as well as the elimination of critical ligand-stabilizing interactions within the LBS are also consequences of this interaction network. Thus, these subtle yet critical structural features are responsible for the weak lysine-binding affinity exhibited by KIV(7) relative to that of KIV(10).

Three new sesquiterpene glycosides from Dendrobium nobile with immunomodulatory activity

Dendroside A (1) and dendronobilosides A and B (2 and 3), three new sesquiterpene glycosides, have been isolated from the stems of Dendrobium nobile, a plant used in Chinese traditional medicine. Their structures and stereochemistry were determined as 10beta,12,14-trihydroxyalloaromadendrane 14-O-beta-D-glucopyranoside (1), 10,12-dihydroxypicrotoxane 10,12-di-O-beta-D-glucopyranoside (2), and 6alpha,10,12-trihydroxypicrotoxane 10-O-beta-D-glucopyranoside (3), respectively, on the basis of spectroscopic and chemical methods. Quantum chemistry calculations were used in support of the structural determination of 1. Compounds 1 and 2 were found to stimulate the proliferation of murine T and B lymphocytes in vitro, while compound 3 showed inhibitory activity in this same assay.

[Degradation of nitrobenzene in water by electrohydrodynamic DC discharge]

In this paper, the experimental results with respect to the degradation of nitrobenzene in water using electrohydrodynamic DC discharge were presented. The DC voltage was 40 kV, the degradation efficiency in the first discharge process reached 50%, the total degradation efficiency in the second discharge process reached 80%. The products contained acetone. At the same time, the degradation efficiency variation with the voltage polarity, flux, and concentration were studied. These studies will be helpful to the treatment of organic wastewater.

Crystal structure of an aldehyde reductase Y50F mutant-NADP complex and its implications for substrate binding

Pig aldehyde reductase containing the active site mutation tyrosine(50) to phenylalanine has been crystallized in the presence of the cofactor NADP(H) to a resolution of 2.2 A. This structure clearly shows loss of the tyrosine hydroxyl group and no other significant perturbations compared with previously determined structures. The mutant binds cofactor (both oxidized and reduced) more tightly than the wild-type enzyme but shows a complete lack of binding of the aldehyde reductase inhibitor barbitone, as determined by fluorescence titrations. Numerous attempts at preparing a ternary complex with a range of small aldehyde substrates were unsuccessful. This result, in addition to the inability of the mutant protein to bind the inhibitor, provides strong evidence for the proposal that the tyrosine hydroxyl group is essential for substrate binding in addition to catalysis.

Functional polymer affinity matrix for purifying hexahistidine-tagged recombinant protein

A functional polyacrylic acid (PAA) adsorbent has been prepared for metal chelate affinity chromatography. It has been found to chelate nickel ion Ni2+ strongly, and was evaluated for the ability to bind proteins containing neighbouring histidine residues. The principle of the technique was illustrated with Aeromonas hydrophila outer membrane protein OmpTS. DNA elements coding for adjacent histidines were fused to the Aeromonas hydrophila ompTS gene. Subsequent expression in E. coli resulted in the production of hybrid protein His6-OmpTS that could be purified by Ni2+-PAA affinity chromatography. The remarkable specificity found makes it an attractive addition to the range of adsorbents for metal chelate affinity chromatography.

Calmodulin protects cells from death under normal growth conditions and mitogenic starvation but plays a mediating role in cell death upon B-cell receptor stimulation

Calmodulin (CaM) is the main intracellular Ca2+ sensor protein responsible for mediating Ca2+ triggered processes. Chicken DT40 lymphoma B cells express CaM from the two genes, CaMI and CaMII. Here we report the phenotypes of DT40 cells with the CaMII gene knocked out. The disruption of the CaMII gene causes the intracellular CaM level to decrease by 60%. CaMII-/- cells grow more slowly and die more frequently as compared to wild type (wt) cells but do not exhibit significant differences in their cell cycle profile. Both phenotypes are more pronounced at reduced serum concentrations. Upon stimulation of the B-cell receptor (BCR), the resting Ca2+ levels remain elevated after the initial transient in CaMII-/- cells. Despite higher Ca2+ resting levels, the CaMII-/- cells are partially protected from BCR induced apoptosis indicating that CaM plays a dual role in apoptotic processes.