Enantioselective total synthesis of callipeltoside A: two approaches to the macrolactone fragment

The enantioselective total synthesis of callipeltoside A is described. Two syntheses of the macrolactone subunit are included: the first relies upon an Ireland-Claisen rearrangement to generate the trisubstituted olefin geometry and the second utilizes an enantioselective vinylogous aldol reaction for this purpose. Enantioselective syntheses of the sugar and chlorocyclopropane side chain fragments are also disclosed. The relative and absolute stereochemistry of this natural product was determined by fragment coupling with the two enantiomers of the side chain fragment.

Discovery of aryl aminoquinazoline pyridones as potent, selective, and orally efficacious inhibitors of receptor tyrosine kinase c-Kit

Inhibition of c-Kit has the potential to treat mast cell associated fibrotic diseases. We report the discovery of several aminoquinazoline pyridones that are potent inhibitors of c-Kit with greater than 200-fold selectivity against KDR, p38, Lck, and Src. In vivo efficacy of pyridone 16 by dose-dependent inhibition of histamine release was demonstrated in a rodent pharmacodynamic model of mast cell activation.

Phosphodiesterase type 2 and the homeostasis of cyclic GMP in living thalamic neurons

The ubiquitous second messenger cyclic GMP (cGMP) is synthesized by soluble guanylate cyclases in response to nitric oxide (NO) and degraded by phosphodiesterases (PDE). We studied the homeostasis of cGMP in living thalamic neurons by using the genetically encoded fluorescence resonance energy transfer sensor Cygnet, expressed in brain slices through viral gene transfer. Natriuretic peptides had no effect on cGMP. Basal cGMP levels decreased upon inhibition of NO synthases or soluble guanylate cyclases and increased when PDEs were inhibited. Single cell RT-PCR analysis showed that thalamic neurons express PDE1, PDE2, PDE9, and PDE10. Basal cGMP levels were increased by the PDE2 inhibitors erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) and BAY60-7550 but were unaffected by PDE1 or PDE10 inhibitors. We conclude that PDE2 regulates the basal cGMP concentration in thalamic neurons. In addition, in the presence of 3-isobutyl-1-methylxanthine (IBMX), cGMP still decreased after application of a NO donor. Probenecid, a blocker of cGMP transporters, had no effect on this decrease, leaving PDE9 as a possible candidate for decreasing cGMP concentration. Basal cGMP level is poised at an intermediate level from which it can be up or down-regulated according to the cyclase and PDE activities.

Phase II study of docetaxel (D) plus bevacizumab (B) in Her/2 negative metastatic breast carcinoma (MBC)

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Background: Taxol+Bevacizumab (B) has clinical activity in Her/2 negative chemotherapy naive MBC with a PFS (11.4 mo), RR (29.9%), and OS (28.4 mo). We are conducting a single arm Phase 2 trial to assess the efficacy of Docetaxel (D)+B. Primary endpoint: time to progression. Secondary endpoints: response rate (CR + PR), response duration, overall survival and safety. Methods: Eligibility criteria: MBC with no prior therapy; Her/2 negative by FISH, ECOG PS 0 or 1; measurable disease by RECIST, Hgb ≥ 9 g/dL, ANC ≥ 1.5 × 109/L, Platelet count ≥ 100 × 109/L, Creatinine ≤ 2.0 mg/dL, Total bilirubin ≤ 1.0 × upper limit of normal, no CNS metastasis, no MI or stroke within 6 mo, no GI perforation, no major surgery within 28 d, and no bleeding diathesis or coagulopathy. Pts receive B 15 mg/kg IV and D 75 mg/m2 IV Q 3 wk. Response assessed radiographically Q 3 cycles. Treatment is until disease progression or unacceptable toxicity. Results: Since Apr 2005, 43 of the planned 75 pts have been enrolled. 21 pts have had at least one assessment resulting in approximately 40% response rate. Common Gr3/4 AE’s have been neutropenia, febrile neutropenia, hypertension. Gr3 LVEF decline seen in one pt. No treatment related deaths occurred. Conclusions: D+ B is well tolerated, with no new safety concerns and manageable toxicities. D+B appears active in MBC. Updated efficacy and safety data will be presented. Study supported by Genentech, Inc. San Francisco, CA.

No significant financial relationships to disclose.

Enhanced degradation efficiency of toluene using titania/silica photocatalysis as a regeneration process

Three kinds of titania/silica pellets were prepared using the sol-gel method with surface areas of 50.4 m2 g(-1), 421.1 m2 x g(-1) and 89.1 m2 x g(-1). An annular reactor was designed and built to determine the degradation efficiency of toluene and to investigate the relationship between the adsorption and desorption-photocatalytic processes. Surface area is an important factor influencing the adsorption-photocatalytic efficiency. Higher surface areas of pellets contribute to high rates of conversion of toluene. Un-reacted toluene and reaction intermediates accumulating on their surface deactivated the titania/silica catalyst. To overcome this problem, the adsorption and regeneration process were alternated in a dual reactor system. Connecting or disconnecting the toluene feed gas enabled one reactor to adsorb toluene, while the second reactor was regenerated by photocatalysis. Using UV irradiation and titania/silica pellets with high BET surface area (421.1 m2 x g(-1)), the alternating adsorption/regeneration processes kept the degradation efficiency of toluene at 90% after 8 hours operation. By improving the adsorption-photocatalysis efficiency, and minimising the generation and accumulation of intermediate on the surface of pellets, the method extended catalyst life and maintained a high degradation efficiency of toluene.

Pyrimidine methyl anilines: selective potentiators for the metabotropic glutamate 2 receptor

Pyrimidine methyl anilines as potent and selective mGlu2 potentiators are described. Findings from the structure-activity-relationship investigations are discussed.

Efficient synthesis of the optically active dihydropyrimidinone of a potent α1A- selective adrenoceptor antagonist

The convergent synthesis of a potent α1A-selective adrenoceptor antagonist is described. Salient features of the synthesis include the enzymatic resolution of a racemic dihydropyrimidinone and the use of a palladium coupling reaction in the synthesis of 2,4'-dipyridyl.Key words: dihydropyrimidinone, enzymatic resolution, palladium coupling.

Enantioselective total synthesis of callipeltoside A

An asymmetric total synthesis of callipeltoside A has been accomplished highlighted by a catalytic enantioselective vinylogous aldol reaction and a boron-mediated anti-aldol reaction influenced by remote stereocontrol.

An aldol-based approach to the asymmetric synthesis of L-callipeltose, the deoxyamino sugar of L-callipeltoside A

[reaction: see text] The L-callipeltose subunit of L-callipeltoside A has been synthesized in 10 steps and 13% overall yield from D-threonine. The key steps are a highly diastereoselective Felkin anti aldol addition to a methyl ketone and a selective methylation of a secondary alcohol in the presence of a secondary carbamate.

Molecular cloning and characterization of profilin-3: a novel cytoskeleton-associated gene expressed in rat kidney and testes

Profilin is a small actin-binding protein that is involved in diverse functions such as maintaining cell structure integrity, cell mobility, tumor cell metastasis, as well as growth factor signal transduction. In this paper, we describe the molecular cloning and characterization of a novel form of profilin, termed profilin-3, from rat kidney using a PCR-based procedure for isolating tissue-specific genes. The profilin-3 cDNA encoded 137 amino acids, and it shared extensive homology to profilin-1 and profilin-2 from mice and humans. More strikingly, the expression of profilin-3 was highly selective, and its mRNA was only found in the kidney and to a much lesser extent in the testis. The size of the mRNA for profilin-3 in the testis was 1.2 kb, while in kidney it was approximately 4.4-5 kb, suggesting the presence of tissue-specific transcription from different promoters. In addition, we also found that the expression of profilin-3 mRNA was significantly elevated in two types of renal diseases: diabetic nephropathy (db/db mice) and polycystic kidney diseases (cpk mice). Similar to profilin-1 and profilin-2, profilin-3 was localized in the cytoplasmic domain. Furthermore, it was capable of interacting with actin and poly-L-proline in an in vitro assay as well as in transfected cells. These results strongly suggest that, contrary to the ubiquitous presence of profilin-1 and profilin-2, there is a tissue-specific form of these cytoskeleton-regulatory proteins and that the kidney/testes-specific profilin-3 may play a unique role in renal and/or reproductive functions.

Pilot study of prevalence of Parkinson's disease in Australia

Parkinson's disease is a common neurological disease and its prevalence increases with age. Because of an ageing population and changing environment compared to the last epidemiological study done in Australia over 30 years ago, we have conducted a door-to-door pilot survey which looked at the latest prevalence as well as putative risk factors in a random population. We used a two-phase investigation method (screening followed by detailed examination) in a random community sample of 2,820 households (with 527 individuals aged 55 and over) along with 203 residents in aged care facilities (single-phase examination for residents aged 55 and above) in the Randwick area of Sydney, New South Wales. We had a 75% participation rate in the community and a 94% in the aged care facilities. The results of the survey in this sample of 730 subjects indicated that the crude prevalence of Parkinson's disease was between 3.6 and 4.9% (higher in the aged care facilities). The putative risk factors positively identified using chi-square method were 'family history' (p < 0.01) and 'exposure to chemicals at work or in surrounding environment' (p < 0.05). The age-adjusted prevalence rate of Parkinson's disease revealed at least a 42.5% increase in the disease compared to 1966. We conclude that there may be an increase in the disease in Australia due to ageing and other risk factors.

Rapid isolation of tissue-specific genes from rat kidney

A systematic effort to isolate kidney-specific genes was performed using recently described PCR-select methodology. Using this technique, a kidney-specific mini-gene library was generated and a number of kidney-specific genes that share significant homology to previously characterized kidney genes from rats and other species were isolated. These included three renal-specific transporters (an ADH water channel, the anion transporters RST and ROAT1), a cell adhesion molecule (K-cadherin) and a kidney-specific protein upregulated in renal carcinoma (DD96). In addition, we isolated two novel genes from a rat kidney. One of the genes shares limited homology to rat profilin-1 while the other did not share any similarity to genes in the Genbank. Northern blot analysis revealed that the mRNA for each of these genes is expressed in a highly kidney-restricted fashion. Our results suggested that tissue-specific genes can be rapidly isolated and characterized using PCR-select techniques and this methodology may be generally applicable to isolate specific genes from a variety of tissues.

A quantum dot single-photon turnstile device

Quantum communication relies on the availability of light pulses with strong quantum correlations among photons. An example of such an optical source is a single-photon pulse with a vanishing probability for detecting two or more photons. Using pulsed laser excitation of a single quantum dot, a single-photon turnstile device that generates a train of single-photon pulses was demonstrated. For a spectrally isolated quantum dot, nearly 100% of the excitation pulses lead to emission of a single photon, yielding an ideal single-photon source.

Mutations that alter the higher-order structure of its 5' untranslated region affect the stability of chloroplast rps7 mRNA

In this paper, we examine the effects of mutations in the 5'UTR of the chloroplast rps7 transcript of Chlamydomonas reinhardtii that reduce the stability of the mRNA. Five point mutants in the rps7 5'UTR were selected on the basis of their failure to accumulate reporter mRNA in Escherichia coli. Each of these mutations produces alterations in the predicted higher-order structures of the rps7 5'UTR that destabilize the mRNA. Cis-acting suppressors of these mutations have been selected in E. coli and in the C. reinhardtii chloroplast that restore message stability and function. No differences in RNA melting and reannealing profiles have been observed between wild type, original mutant, and suppressor 5'UTRs transcribed in vitro. Proteins of 32 kDa and 47 kDa that bind to the wild-type rps7 5'UTR are not detected by UV cross-linking assays performed with any of the mutant rps7 5'UTRs. However, binding of the 32-kDa protein is restored in the six suppressor mutants examined. This suggests that the 32-kDa protein may be involved in protecting the rps7 5'UTR and the attached coding region from digestion by ribonucleases. Alternatively, the binding site for the 32-kDa protein may be independently lost in the rearranged tertiary structure of the mutant 5'UTR that exposes the RNA to degradation and is restored in the suppressor mutants.

Identification of a novel kidney-specific gene downregulated in acute ischemic renal failure

To gain further insights into the molecular mechanisms involved in acute renal failure, we have isolated a new gene from rat and human, named KSP32 (kidney-specific protein with a molecular mass of 32 kDa). KSP32 encodes a novel gene that shows little homology to other mammalian proteins. It, however, shares extensive homology with several proteins found in the nematode Caenorhabditis elegans and plants. The expression of KSP32 mRNA is highly restricted to kidney. In situ hybidization analysis revealed that the expression of KSP32 mRNA was prominent in the boundary of kidney cortex and outer medulla, exhibiting a raylike formation extending from the medulla into the cortex. Finally, KSP32 mRNA was dramatically downregulated in rat following induction of acute ischemic renal failure. Rapid loss of KSP32 mRNA expression was observed beginning at approximately 5 h following renal injury and mRNA levels remained depressed for at least 96 h. Both KSP32 mRNA levels as well as renal function recovered 14 days after injury. Administration of an endothelin receptor antagonist (SB-209670), known to restore renal function, significantly increased KSP32 expression.

Validating a screening questionnaire for parkinsonism in Australia

Parkinson's disease is a common neurodegenerative disorder in elderly people. Epidemiological studies of the disease can be labour intensive. A two phase design including a screening questionnaire as the first phase has become a popular method in prevalence studies of Parkinson's disease. Such a design has many advantages including less work for assessing physicians and enhanced recruitment of people to be screened. However, its wider application may be questioned because validation has been limited to samples that are drawn from hospitals (or clinics) and may be inappropriate for a community setting. This study assesses whether validating screening questionnaire by using a hospital sample yields the same result as a community based sample. Furthermore, it seeks to establish whether the screening instrument can be simplified to involve less questions. The findings show that some of the questions used in the screening phase yield different responses when comparing a hospital group with a community group. This study also provides a simplified model of questions that may be relevant for screening in the community setting.

Cloning and characterization of a novel human class I histone deacetylase that functions as a transcription repressor

Histone acetylation alters chromatin state by modifying lysines on histone and plays an important role in modulating gene transcription. A dynamic balance of histone acetylation/deacetylation is maintained by histone acetyltransferases and histone deacetylases. Emerging evidence suggests that a family of histone deacetylases may exist to regulate diverse cellular functions, including chromatin structure, gene expression, cell cycle progression, and oncogenesis. We describe here a novel human histone deacetylase, named HDAC8, cloned from human kidney. HDAC8 encodes 377 amino acid residues and shares extensive homology to several known HDACs, in particular a histone deacetylase from Arabidopsis thaliana. Northern blot analyses revealed that HDAC8 expression pattern for HDAC8 is distinct from that for HDAC1 and HDAC3, and expression of HDAC8 mRNA occurs in multiple organs including heart, lung, kidney, and pancreas. HDAC8 mRNA was also observed in several cell lines derived from cancerous tissues. When expressed in HEK293 cells, HDAC8 exhibited deacetylase activity toward acetylated histone, indicating that this protein is a bona fide histone deacetylase. Its histone deacetylase activity was inhibited by trichostatin and other known histone deacetylase inhibitors. Furthermore, active recombinant HDAC8 was expressed and purified from Escherichia coli. When ectopically expressed in cells, HDAC8 was found to be localized to the nucleus. Co-transfection experiments demonstrated that expression of HDAC8 repressed a viral SV40 early promoter activity. These results indicate that HDAC8 is a novel member of the histone deacetylase family, which may play a role in the development of a broad range of tissues and potentially in the etiology of cancer.

Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs

The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator that is relatively insensitive to population evolution. Here we use a k-corrected and evolution-compensated volume-limited sample having an R-band absolute magnitude of Mk,eR</=-19.8+5logh mag drawing about 300 redshifts from the Caltech Faint Galaxy Redshift Survey and 3000 from the Canadian Network for Observational Cosmology field galaxy survey to measure the rate and redshift evolution of merging. The combined sample has an approximately constant comoving number and luminosity density from redshift 0.1 to 1.1 (OmegaM=0.2, OmegaLambda=0.8); hence, any merger evolution will be dominated by correlation and velocity evolution, not density evolution. We identify kinematic pairs with projected separations less than either 50 or 100 h-1 kpc and rest-frame velocity differences of less than 1000 km s-1. The fractional luminosity in pairs is modeled as fL&parl0;Deltav,rp,Mk,er&parr0;&parl0;1+z&parr0;mL, where &sqbl0;fL,mL&sqbr0; are &sqbl0;0.14+/-0.07,0+/-1.4&sqbr0; and &sqbl0;0.37+/-0.7,0.1+/-0.5&sqbr0; for rp</=50 and 100 h-1 kpc, respectively (OmegaM=0.2, OmegaLambda=0.8). The value of mL is about 0.6 larger if Lambda=0. To convert these redshift-space statistics to a merger rate, we use the data to derive a conversion factor to a physical space pair density, a merger probability, and a mean in-spiral time. The resulting mass accretion rate per galaxy (M1,M2>/=0.2M*) is 0.02+/-0.01&parl0;1+z&parr0;0.1+/-0.5M* Gyr-1. Present-day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift 1. Since merging is likely only weakly dependent on the host mass, the fractional effect, deltaM&solm0;M approximately 0.15M*&solm0;M, is dramatic for lower mass galaxies but is, on the average, effectively perturbative for galaxies above 1M*.

Overexpression of ribonucleotide reductase as a mechanism of resistance to 2,2-difluorodeoxycytidine in the human KB cancer cell line

In this study, human oropharyngeal epidermoid carcinoma KB cells that were resistant to 2,2-difluorodeoxycytidine (dFdCyd) were selected and designated the KB-Gem clone. The KB parental cell line IC50 was 0.3 microM dFdCyd, as compared with the KB-Gem clone IC50 of 32 microM dFdCyd. The KB-Gem clone demonstrated overexpression of ribonucleotide reductase (RR) M2 subunit mRNA (9-fold) and overexpression of M2 protein (2-fold); RR activity was 2.3-fold higher than the KB parental cell line. Both the dATP and dCTP pools of the KB-Gem clone increased 2-fold over the parental cell line, with no change in the dGTP and dTTP pools. Reverse transcriptase-PCR was used to clone the cDNA of deoxycytidine kinase (DCK). Resulting sequences revealed two silent mutations in the KB-Gem clone. The amino acid sequence of the DCK protein and mRNA expression remained unchanged. The KB-Gem clone's DCK enzyme activity was 56% of that of the parental cell line. After the endogenous dNTPs were removed with a G-25 column, no difference was evident between the enzyme activities of the KB-Gem clone and parental cells. Thus, contrary to previous hypotheses, DCK deficiency does not play the primary role in the resistance mechanism of dFdCyd, accepting a secondary role to the overexpression of the target gene, RR, and pool expansion.

DEF-1, a novel Src SH3 binding protein that promotes adipogenesis in fibroblastic cell lines

The Src homology 3 (SH3) motif is found in numerous signal transduction proteins involved in cellular growth and differentiation. We have purified and cloned a novel protein, DEF-1 (differentiation-enhancing factor), from bovine brain by using a Src SH3 affinity column. Ectopic expression of DEF-1 in fibroblasts resulted in the differentiation of a significant fraction of the culture into adipocytes. This phenotype appears to be related to the induction of the transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), since DEF-1 NIH 3T3 cells demonstrated augmented levels of PPARgamma mRNA and, when treated with activating PPARgamma ligands, efficient induction of differentiation. Further evidence for a role for DEF-1 in adipogenesis was provided by heightened expression of DEF-1 mRNA in adipose tissue isolated from obese and diabetes mice compared to that in tissue isolated from wild-type mice. However, DEF-1 mRNA was detected in multiple tissues, suggesting that the signal transduction pathway(s) in which DEF-1 is involved is not limited to adipogenesis. These results suggest that DEF-1 is an important component of a signal transduction process that is involved in the differentiation of fibroblasts and possibly of other types of cells.

Tissue restricted expression of two human Frzbs in preadipocytes and pancreas

Frzb is a newly discovered family of secreted glycoproteins that function to modulate signaling activity of Wnt. Frzb proteins share sequence homology with the extracellular domain of the Wnt receptor (frizzled) and are capable of binding to Wnt. Thus, Frzb functions to antagonize Wnt activity by sequestering Wnt and preventing its binding to the frizzled receptor. Since the initial identification of bovine and human Frzb, several related members of this family have been isolated from rodent and human. In this paper, we describe the cloning and expression of two human frzb homologues termed hFRP-1b and hFRP-2. These human FRPs share significant homology to mouse sFRP-1 and sFRP-2 (55 and 98% identity at amino acid level, respectively). Northern blot experiments revealed that these Frzb homologues have highly restricted tissue distribution. hFRP-1b is exclusively expressed in pancreatic tissue while high levels of hFRP-2 were found in adipose tissue. In addition, low levels of hFRP-2 were also observed in other tissues including heart, pancreas and muscle. Remarkably, FRP-2 is predominantly expressed in un-differentiated preadipocytes in both rodent and man. The expression of FRP-2 is also significantly reduced in fat pads from obese mice. Taken together, these data indicate that distinctive members of the Frzb family exhibit different expression patterns in vivo, suggesting their ability to modulate diverse aspects of Wnt signaling. The expression and dysregulation of sFRP-2 in fat and obesity also suggest a potential roles on the Wnt signaling pathway in the pathology of obesity and related metabolic diseases. Molecular cloning and expression of these Frzbs will allow detailed molecular and biochemical analysis of Wnt-Frzb interaction and their impact on Wnt-Frizzled receptor signal transduction.

Short-wave cone signal in the red-green detection mechanism

Previous work shows that the red-green (RG) detection mechanism is highly sensitive, responding to equal and opposite long-wave (L) and middle-wave (M) cone contrast signals. This mechanism mediates red-green hue judgements under many conditions. We show that the RG detection mechanism also receives a weak input from the short-wave (S) cones that supports the L signal and equally opposes M. This was demonstrated with a pedestal paradigm, in which weak S cone flicker facilitates discrimination and detection of red-green flicker. Also, a near-threshold +S cone flash facilitates detection of red flashes and inhibits green flashes, and a near-threshold -S cone flash facilitates detection of green flashes and inhibits red flashes. The S contrast weight in RG is small relative to the L and M contrast weights. However, a comparison of our results with other studies suggests that the strength of the absolute S cone contrast contribution to the RG detection mechanism is 1/4 to 1/3 the strength of the S contribution to the blue-yellow (BY) detection mechanism. Thus, the S weight in RG is a significant fraction of the S weight in BY. This has important implications for the 'cardinal' color mechanisms, for it predicts that for detection or discrimination, the mechanisms limiting performance do not lie on orthogonal M-L and S axes within the equiluminant color plane.