Retention model for proteins in reversed-phase liquid chromatography

This paper presents a retention model for proteins on an reversed-phase chromatography support in which retention is a function of the number (Z) of solvent molecules required to displace the solute from the surface. An equation is derived that relates the capacity factor of a protein to the displacing agent concentration and the stoichiometry of solvent-solute displacement. Experimental tests of the model indicate that each protein has a unique Z value and that Z is directly proportional to the molecular weight of a series of proteins when 60% formic acid is used as the mobile phase additive. This relationship is attributed to a direct relationship between Z and the contact surface area between polypeptide solutes and the support. Desorption curves for proteins also become more convex with increasingly molecular weight, as predicted by the retention model. In the solvent series of methanol, ethanol, propanol, the Z number decreases from the C1 to C3 alcohol. The Z number for any particular solvent is also related to other mobile phase additives, such as acids, and the concentration of additives.

Mutational analysis of genes involved in pilus structure, motility and transformation competency in the unicellular motile cyanobacterium Synechocystis sp. PCC 6803

The relevance of pilus-related genes to motility, pilus structure on the cell surface and competency of natural transformation was studied by gene disruption analysis in the unicellular motile cyanobacterium Synechocystis: sp. PCC 6803. The genes disrupted in this study were chosen as related to the pil genes for biogenesis of the type IV pili in a Gram-negative bacterium Pseudomonas aeruginosa. It was found that motility of Synechocystis cells was lost in the mutants of slr0063, slr1274, slr1275, slr1276, slr1277 and sll1694 together with a simultaneous loss of the thick pili on the cell surface. Competency of the natural transformation was lost in the mutants listed above and slr0197-disruptant. The gene slr0197 was previously predicted as a competence gene by a search with sequence-independent DNA-binding structure [Yura et al. (1999) DNA Res. 6: 75]. It was suggested that both DNA uptake for natural transformation and motility are mediated by a specific type IV-like pilus structure, while a putative DNA-binding protein encoded by slr0197 is additionally required for the DNA uptake. Based on the homology with the pil genes in P: aeruginosa, slr0063, slr1274, slr1275, slr1276, slr1277 and sll1694 were designated pilB1, pilM, pilN, pilO, pilQ and pilA1, respectively. The gene slr0197 was designated comA.

Prospective evaluation of the cardiac safety of HER2-targeted therapies in patients with HER2-positive breast cancer and compromised heart function: the SAFE-HEaRt study

Purpose

HER2-targeted therapies have substantially improved the outcome of patients with breast cancer, however, they can be associated with cardiac toxicity. Guidelines recommend holding HER2-targeted therapies until resolution of cardiac dysfunction. SAFE-HEaRt is the first trial that prospectively tests whether these therapies can be safely administered without interruptions in patients with cardiac dysfunction.

Methods

Patients with stage I–IV HER2-positive breast cancer candidates for trastuzumab, pertuzumab or ado-trastuzumab emtansine (TDM-1), with left ventricular ejection fraction (LVEF) 40–49% and no symptoms of heart failure (HF) were enrolled. All patients underwent cardiology visits, serial echocardiograms and received beta blockers and ACE inhibitors unless contraindicated. The primary endpoint was completion of the planned HER2-targeted therapies without developing either a cardiac event (CE) defined as HF, myocardial infarction, arrhythmia or cardiac death or significant asymptomatic worsening of LVEF. The study was considered successful if planned oncology therapy completion rate was at least 30%.

Results

Of 31 enrolled patients, 30 were evaluable. Fifteen patients were treated with trastuzumab, 14 with trastuzumab and pertuzumab, and 2 with TDM-1. Mean LVEF was 45% at baseline and 46% at the end of treatment. Twenty-seven patients (90%) completed the planned HER2-targeted therapies. Two patients experienced a CE and 1 had an asymptomatic worsening of LVEF to ≤ 35%.

Conclusion

This study provides safety data of HER2-targeted therapies in patients with breast cancer and reduced LVEF while receiving cardioprotective medications and close cardiac monitoring. Our results demonstrate the importance of collaboration between cardiology and oncology providers to allow for delivery of optimal oncologic care to this unique population.

Electronic supplementary material

The online version of this article (10.1007/s10549-019-05191-2) contains supplementary material, which is available to authorized users.

Tropomyosin isoforms in intestinal mucosa: production of autoantibodies to tropomyosin isoforms in ulcerative colitis

BACKGROUND & AIMS

Autoantibodies against tropomyosins (TMs) have been reported in ulcerative colitis (UC). In this study the hTM isoforms (hTM1-5) present in intestinal epithelial cells and in smooth muscle were investigated, and the immunoreactivity against hTMs by immunoglobulin G (IgG) produced in vitro by colonic mucosal lymphocytes (LPMCs) from patients with UC, Crohn's disease (CD), and controls was examined.

METHODS

TMs were extracted from colonic and jejunal epithelial cells and smooth muscle, and hTM isoforms were identified using isoform-specific monoclonal antibodies by enzyme-linked immunosorbent assay and transblot analysis. The immunoreactivity of IgG produced by colonic LPMCs was analyzed against the recombinant hTM isoforms.

RESULTS

The major hTM isoforms present in colonic and jejunal epithelial cells are hTM5 and hTM4, whereas intestinal smooth muscle contains the hTM1-3 isoforms. The IgG synthesized in vitro by LPMCs from UC (n = 19) recognized hTM5 and hTM1, more significantly (P < 0.04 to <0.001) when compared with CD (n = 12) and controls (n = 17). However, IgG produced by LPMCs from CD did not show such anti-hTM reactivity. Mucosal anti-hTM IgG mainly belonged to the IgG1 subclass.

CONCLUSIONS

Intestinal epithelial cells and smooth muscle have distinct hTM isoforms. Patients with UC, and not CD, show mucosal autoantibody response against hTM isoforms, particularly hTM5 and hTM1.

Stoichiometric displacement of solvent by non-polar solutes in reversed-phase liquid chromatography

This paper proposes a retention model which predicts that the displacement of non-polar solutes from a reversed-phase chromatographic column is accompanied by the adsorption of a stoichiometric number (Z) of solvent molecules. The number of solvent molecules involved in this process is a function of both solute and solvent contact surface areas. Increasing solute contact surface area would increase Z whereas increasing solvent contact surface area would decrease the Z value for a specific solute. The experimental observations presented are consistent with this model. Further predictions of the model are that (1) plots of log k' versus the inverse log of solvent concentration will be non-linear at solvent concentrations where the surface of a reversed-phase support is not fully solvated, and (2) only a portion of the total non-polar surface area of a molecule actually contacts the surface of a reversed-phase support. Non-linearity in plots of log k' versus the inverse log of solvent concentration was in fact observed at solvent concentrations where solvation of the reversed-phase support is incomplete.

Synthesis and structure-activity relationships of new second-generation taxoids

A series of second-generation taxoids bearing a substituent on the C-2-benzoyl group and modifications at C-3'/C-10 positions was synthesized. These taxoids exhibited 2-3 orders of magnitude higher potency than that of paclitaxel against drug-resistant human breast cancer cell lines. It is also noteworthy that three taxoids showed almost no difference in activity against drug-resistant and drug-sensitive cell lines, which are categorized as "advanced second generation taxoids".

Structural phosphoprotein M2-1 of the human respiratory syncytial virus is an RNA binding protein

The structural phosphoprotein M2-1 of human respiratory syncytial virus (HRSV) Long strain shows RNA binding capacity in three different assays that detect RNA-protein complexes: cross-linking, gel retardation, and Northern-Western assays. It is able to bind HRSV leader RNA specifically with cooperative kinetics, with an apparent K(d) of at least 90 nM. It also binds to long RNAs with no sequence specificity. The RNA binding domain has been located between amino acid residues 59 and 85, at the NH(2) terminus of the protein. This region contains the phosphorylatable amino acid residues threonine 56 and serine 58, whose modification decreases the binding capacity of M2-1 protein to long RNAs.

Degradation of non-phenolic lignin by the white-rot fungus Pycnoporus cinnabarinus

High-molecular-weight lignin was methylated with diazomethane. The lignin (i.e., phenolic lignin) and methylated lignin (i.e., non-phenolic lignin) were mixed with fully bleached softwood pulp. Degradation of the lignin preparations by the white rot fungus Pycnoporus cinnabarinus was studied. After a 3-month incubation with the fungus, over 40% of the non-phenolic lignin and about 70% the phenolic lignin were degraded. The presence of phenolic hydroxyl groups in lignin greatly enhanced the degradation rate of lignin. This study reveals that P. cinnabarinus, an exclusively laccase-producing fungus, is capable of oxidatively degrading both phenolic and non-phenolic lignins. The ability of the fungus to degrade non-phenolic lignin suggests that a laccase/mediator system is involved in the complete degradation of lignin. After the fungal degradation of lignins, the content of carboxylic acids substantially increased for both phenolic and non-phenolic lignins.

C-peptide reduces high-glucose-induced apoptosis of endothelial cells and decreases NAD(P)H-oxidase reactive oxygen species generation in human aortic endothelial cells

AIMS/HYPOTHESIS

Reactive oxygen species (ROS) generated during hyperglycaemia are implicated in the development of diabetic vascular complications. High glucose increases oxidative stress in endothelial cells and induces apoptosis. A major source of ROS in endothelial cells exposed to glucose is the NAD(P)H oxidase enzyme. Several studies demonstrated that C-peptide, the product of proinsulin cleavage within the pancreatic beta cells, displays anti-inflammatory effects in certain models of vascular dysfunction. However, the molecular mechanism underlying this effect is unclear. We hypothesised that C-peptide reduces glucose-induced ROS generation by decreasing NAD(P)H oxidase activation and prevents apoptosis

METHODS

Human aortic endothelial cells (HAEC) were exposed to 25 mmol/l glucose in the presence or absence of C-peptide and tested for protein quantity and activity of caspase-3 and other apoptosis markers by ELISA, TUNEL and immunoblotting. Intracellular ROS were measured by flow cytometry using the ROS sensitive dye chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H(2)-DCDFA). NAD(P)H oxidase activation was assayed by lucigenin. Membrane and cytoplasmic levels of the NAD(P)H subunit ras-related C3 botulinum toxin substrate 1 (rho family, small GTP binding protein Rac1) (RAC-1) and its GTPase activity were studied by immunoblotting and ELISA. RAC-1 (also known as RAC1) gene expression was investigated by quantitative real-time PCR.

RESULTS

C-peptide significantly decreased caspase-3 levels and activity and upregulated production of the anti-apoptotic factor B cell CLL/lymphoma 2 (BCL-2). Glucose-induced ROS production was quenched by C-peptide and this was associated with a decreased NAD(P)H oxidase activity and reduced RAC-1 membrane production and GTPase activity.

CONCLUSIONS/INTERPRETATION

In glucose-exposed endothelial cells, C-peptide acts as an endogenous antioxidant molecule by reducing RAC-1 translocation to membrane and NAD(P)H oxidase activation. By preventing oxidative stress, C-peptide protects endothelial cells from glucose-induced apoptosis.

Tubulins in the primate retina: evidence that xanthophylls may be endogenous ligands for the paclitaxel-binding site

The xanthophylls-lutein, zeaxanthin, and meso-zeaxanthin (L&Z)-are found in the central region of the primate retina, which is called the macula lutea (yellow spot). How they are anchored there and what their function is has been debated for over 50 years. Here, we present evidence that they may be bound to the paclitaxel (Taxol) binding site of the beta-tubulin subunit of microtubules and that a major function may be to modulate the dynamic instability of microtubules in the macula. Also, we compare nucleic acid and amino acid sequences of tubulins that are in human brain with those we have isolated from human-retina and monkey-macula cDNA libraries. In so doing, we suggest that in primates, class I beta-tubulin consists of at least two subtypes (beta(Ia) and beta(Ib)). Alignment analysis of the sequences of the genes for beta(Ia) and beta(Ib) indicates that the corresponding mRNAs may have other functions in addition to that of coding for proteins. Furthermore, we show that there are at least five different types of beta-tubulin in the macula lutea of rhesus monkey.

A genome-wide association study of heat stress-associated SNPs in catfish

Heat tolerance is a complex and economically important trait for catfish genetic breeding programs. With global climate change, it is becoming an increasingly important trait. To better understand the molecular basis of heat stress, a genome-wide association study (GWAS) was carried out using the 250 K catfish SNP array with interspecific backcross progenies, which derived from crossing female channel catfish with male F1 hybrid catfish (female channel catfish × male blue catfish). Three significant associated SNPs were detected by performing an EMMAX approach for GWAS. The SNP located on linkage group 14 explained 12.1% of phenotypical variation. The other two SNPs, located on linkage group 16, explained 11.3 and 11.5% of phenotypical variation respectively. A total of 14 genes with heat stress related functions were detected within the significant associated regions. Among them, five genes-TRAF2, FBXW5, ANAPC2, UBR1 and KLHL29- have known functions in the protein degradation process through the ubiquitination pathway. Other genes related to heat stress include genes involved in protein biosynthesis (PRPF4 and SYNCRIP), protein folding (DNAJC25), molecule and iron transport (SLC25A46 and CLIC5), cytoskeletal reorganization (COL12A1) and energy metabolism (COX7A2, PLCB1 and PLCB4) processes. The results provide fundamental information about genes and pathways that is useful for further investigation into the molecular mechanisms of heat stress. The associated SNPs could be promising candidates for selecting heat-tolerant catfish lines after validating their effects on larger and various catfish populations.

Facile, tunable, and SERS-enhanced HEPES gold nanostars

The facile, green synthesis of gold nanostars (AuNSs) with tunable branch lengths for SERS applications.

C-peptide is internalised in human endothelial and vascular smooth muscle cells via early endosomes

AIMS/HYPOTHESIS

There is increasing evidence that C-peptide exerts intracellular effects in a variety of cells and could be beneficial in patients with type 1 diabetes. Exactly how C-peptide achieves these effects, however, is unknown. Recent reports showed that C-peptide internalised in the cytoplasm of HEK-293 and Swiss 3T3 cells, where it was not degraded for at least 1 h after uptake. In this study, we investigated the hypothesis that C-peptide is internalised via an endocytic pathway and traffics to classic endocytic organelles, such as endosomes and lysosomes.

METHODS

We studied the internalisation of C-peptide in vascular endothelial and smooth muscle cells, two relevant targets of C-peptide activity, by using Alexa Fluor-labelled C-peptide probes in living cells and immunohistochemistry employing confocal laser-scanning microscopy. To examine trafficking to subcellular compartments, we used fluorescent constructs tagged to RAB5A, member RAS oncogene family (RAB5A) to identify early endosomes, or to lysosomal-associated membrane protein 1 (LAMP1) to identify lysosomes.

RESULTS

C-peptide internalised in the cytoplasm of cells within punctate structures identified as early endosomes. Internalisation was clearly detectable after 10 min of incubation and was blocked at 4 degrees C as well as with excess of unlabelled C-peptide. A minor fraction of vesicles, which increased with culture time, co-localised with lysosomes. Uptake of C-peptide was reduced by monodansylcadaverine, a pharmacological compound that blocks clathrin-mediated endocytosis, and by nocodazole, which disrupts microtubule assembly.

CONCLUSIONS/INTERPRETATION

C-peptide internalises in the cytoplasm of cells by endocytosis, as demonstrated by its localisation in early endosomes. Endosomes might represent a signalling station, through which C-peptide might achieve its cellular effects.

Externalization of tropomyosin isoform 5 in colon epithelial cells

Ulcerative colitis (UC) is associated with autoantibody response to a cytoskeletal protein, human tropomyosin (hTM) isoform-5 (hTM5). Because hTM5 is an intracellular protein, it may remain inaccessible to the autoantibodies. Therefore, we have investigated the possibility of externalization of hTM5 in colon epithelial cells. Freshly isolated colonic and small intestinal epithelial cells and LS-180 colon cancer cell line were examined for surface expression of hTM5 by flow cytometric analysis using hTM isoform-specific MoAbs. The extracellular release of hTM5 was determined by Western blot and radioimmunoprecipitation analyses. Physical association of hTM5 with a membrane-associated colon epithelial protein (CEP) was examined by co-immunoprecipitation of hTM5 with anti-CEP MoAb, and CEP with anti-hTM5 MoAb. Cell surface expression of hTM5 was observed in colonic epithelial and LS-180 cells but not in small intestinal epithelial cells. LS-180 cells spontaneously released hTM5 as well as CEP into the culture medium that was significantly stimulated by a calcium ionophore, A23187, but inhibited by phorbol-12-myristate-13-acetate, monensin and methylamine. Co-immunoprecipitation experiments revealed that hTM5 forms a complex with CEP. We conclude that hTM5 is externalized in colon but not in small intestinal epithelial cells. The physical association of hTM5 with CEP suggests a possible chaperone function of CEP in the transport of hTM5, a putative target autoantigen in UC.

Patients with inflammatory bowel disease may have a transforming growth factor-beta-, interleukin (IL)-2- or IL-10-deficient state induced by intrinsic neutralizing antibodies

Ulcerative colitis (UC) and Crohn's disease (CD) are considered to be immunologically mediated disorders that share certain features with murine models of colitis. Whether any of these models are physiologically relevant to the human condition remains controversial. The hypothesis is that increased amounts of antibodies neutralizing transforming growth factor (TGF)-beta, interleukin (IL)-2 or IL-10 create a relative immunodeficient state in inflammatory bowel disease (IBD) that predisposes to disease. To evaluate this, serum samples from patients with UC or CD and from normal healthy individuals were studied by enzyme-linked immunosorbent assays. Antibodies recognizing TGF-beta were most prevalent in UC (P<0.01); anti-IL-10 antibodies were elevated in CD (P<0.05), while anti-IL-2 antibodies were the same for all three groups. Importantly, the percentage of IBD patients with at least one of the antibody levels greater than any control value was 30% for UC and 33% for CD. To verify the presence of these antibodies, immobilized TGF-beta was exposed to UC sera and the attached proteins identified by Western blot assay. The proteins proved to be exclusively immunoglobulin (Ig) G. To evaluate the neutralizing activity of these antibodies, cytokine-specific IgG from subjects in each group of patients was incubated with TGF-beta, IL-2 or IL-10 before addition to a bioassay with changes in viability determined by a colorimetric analysis. Antibodies from most individuals in all three groups neutralized the action of each cytokine. This study shows that about one-third of IBD patients may have a relative deficiency of TGF-beta, IL-2 or IL-10 due to an increase in neutralizing antibodies in their sera.

High-density interspecific genetic linkage mapping provides insights into genomic incompatibility between channel catfish and blue catfish

Catfish is the leading aquaculture species in the United States. The interspecific hybrid catfish produced by mating female channel catfish with male blue catfish outperform both of their parent species in a number of traits. However, mass production of the hybrids has been difficult because of reproductive isolation. Investigations of genome structure and organization of the hybrids provide insights into the genetic basis for maintenance of species divergence in the face of gene flow, thereby helping develop strategies for introgression and efficient production of the hybrids for aquaculture. In this study, we constructed a high-density genetic linkage map using the hybrid catfish system with the catfish 250K SNP array. A total of 26,238 SNPs were mapped to 29 linkage groups, with 12,776 unique marker positions. The linkage map spans approximately 3240 cM with an average intermarker distance of 0.25 cM. A fraction of markers (986 of 12,776) exhibited significant deviation from the expected Mendelian ratio of segregation, and they were clustered in major genomic blocks across 15 LGs, most notably LG9 and LG15. The distorted markers exhibited significant bias for maternal alleles among the backcross progenies, suggesting strong selection against the blue catfish alleles. The clustering of distorted markers within genomic blocks should lend insights into speciation as marked by incompatibilities between the two species. Such findings should also have profound implications for understanding the genomic evolution of closely related species as well as the introgression of hybrid production programs in aquaculture.

Investigation of hydroxamic acids as laccase-mediators for pulp bleaching

A number of hydroxamic acids have been synthesized and investigated as laccase-mediators for pulp bleaching. As compared with N-hydroxyacetanilide (NHA), one of the most effective laccase-mediators reported so far, N-(4-cyanophenyl)acetohydroxamic acid (NCPA), resulted in the highest brightness and lowest kappa number of hardwood kraft pulp of all the laccase-mediators studied. The bleaching efficacy of a laccase/7-cyano-4-hydroxy-2H-1,4-benzoxazin-3-one system was also comparable with that of a laccase/NHA system. A laccase/NCPA system was further studied for the bleaching of unbleached softwood kraft pulp. The effects of pulp consistency, laccase dosage, NCPA dosage, incubation time, and oxygen pressure on the bleaching efficacy of a laccase/NCPA system were studied.

Efficient delivery of lentiviral vectors into resting human CD4 T cells

Resting human CD4 T cells are highly resistant to transfection or infection with lentiviral vectors derived from the human immunodeficiency virus. We now describe a flexible and efficient approach involving virus-like particles containing simian immunodeficiency virus lentiviral gene product protein X and pseudotyping with CXCR4-tropic HIV Env. This method permits effective genetic manipulation of these cells while preserving their naturally quiescent state. This technology can also be extended to primary lymphoid cultures where authentic cellular composition and functional relationships are preserved.

Occurrence and sources of PCBs, PCNs, and HCB in the atmosphere at a regional background site in east China: Implications for combustion sources

Multiple types of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), and hexachlorobenzene (HCB), can be unintentionally released from combustion or thermal industrial processes, which are speculated to be the main sources of these contaminants, as they were banned on production and use since several decades ago. In this study, concentrations and sources of 40 PCBs, 39 PCNs, and HCB were analyzed in air samples collected during the period 2012-2015 at a background site in east China. ΣPCBs, ΣPCNs, and HCB were in the range of 9-341 pg/m³, 6-143 pg/m³, and 14-522 pg/m³, respectively. Seasonal characteristics with high levels in winter and low levels in summer were observed for PCNs and HCB. PCBs also exhibited slightly higher levels in winter. Source apportionment was conducted, using polycyclic aromatic hydrocarbons (PAHs) as combustion sources indicator, combined with principal component analysis (PCA) and positive matrix factorization (PMF) model. The results indicated that the legacy of past produced and used commercial PCBs was the dominant contributor (∼56%) to the selected PCBs in the atmosphere in east China. PCNs were mainly emitted from combustion sources (∼64%), whereas HCB almost entirely originated from combustion process (>90%).

Sources, compositions, and optical properties of humic-like substances in Beijing during the 2014 APEC summit: Results from dual carbon isotope and Fourier-transform ion cyclotron resonance mass spectrometry analyses

Humic-like substances (HULIS) are a class of high molecular weight, light-absorbing compounds that are highly related to brown carbon (BrC). In this study, the sources and compositions of HULIS isolated from fine particles collected in Beijing, China during the 2014 Asia-Pacific Economic Cooperation (APEC) summit were characterized based on carbon isotope (¹³C and ¹⁴C) and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses, respectively. HULIS were the main light-absorbing components of water-soluble organic carbon (WSOC), accounting for 80.2 ± 6.1% of the WSOC absorption capacity at 365 nm. The carbon isotope data showed that HULIS had a lower non-fossil contribution (53 ± 4%) and were less enriched with ¹³C (-24.2 ± 0.6‰) relative to non-HULIS (62 ± 8% and -20.8 ± 0.3‰, respectively). The higher relative intensity fraction of sulfur-containing compounds in HULIS before and after APEC was attributed to higher sulfur dioxide levels emitted from fossil fuel combustion, whereas the higher fraction of nitrogen-containing compounds during APEC may have been due to the relatively greater contribution of non-fossil compounds or the influence of nitrate radical chemistry. The results of investigating the relationships among the sources, elemental compositions, and optical properties of HULIS demonstrated that the light absorption of HULIS appeared to increase with increasing unsaturation degree, but decrease with increasing oxidation level. The unsaturation of HULIS was affected by both sources and aging level.

A meta-analysis on the association of HER-2 overexpression with prognosis in human osteosarcoma

Various studies examining the relationship between HER-2 overexpression and clinical outcome in patients with osteosarcoma have yielded inconclusive results. The purpose of the current study was to evaluate the relation of HER-2 status with clinical outcome in osteosarcoma. We conducted a meta-analysis of five studies that evaluated the relation between HER-2 status and 2-year survival. DerSimonian-Laird random effects analysis was used to estimate the effects of HER-2 overexpression on 2-year survival. The combined relative risk in patients with osteosarcoma for 2-year survival was 1.26 (95% confidence interval, 0.50-3.14; P = 0.63). HER-2-positive status tended to be associated with a worse 2-year survival, but the overall results were not formally statistically significant. An unfavourable prognostic effect of HER-2 overexpression in osteosarcoma was evident from the meta-analysis. However, because several studies were excluded by the current eligibility criteria, caution is needed in interpreting the results.

Single crystal PZN/PT-polymer composites for ultrasound transducer applications

Single crystal relaxor ferroelectrics of PZN-8%PT were investigated for potential application in ultrasound transducers. The full set of electromechanical properties was determined using combined resonance and laser interferometry techniques. Ultra-high length extensional coupling (k(33)) of 0.94 was observed, a 25% increase over Navy Type VI PZT ceramics. The thickness extensional coupling (k(t)) of 0.48 was comparable to PZT compositions, and the compliance S(33)(E) was a factor of six greater. To maximize height extensional coupling (k'(33)), while minimizing length extensional coupling k(31) in array elements, it was necessary to align the elements along the 100 crystallographic direction in the x-y plane. Mode coupling plots and test samples for array elements determined that width-to-height ratios of less than 0.5 were desired, similar to the requirement for polycrystalline PZT ceramics. Modeling of 1-3 composites and experimental results demonstrated that thickness coupling greater than 0.80 could be achieved with a 40% to 70% volume fraction of PZN-PT. Although this is a substantial increase over PZT 1-3 composites, with a thickness coupling coefficient of 0.66, it represents a smaller fraction of the length extensional coupling k(33). This reduction may be a consequence of the increased compliance of PZN-PT, which results in significant clamping by the polymer matrix. Ultrasonic transducers fabricated using PZN-8%PT 1-3 composites achieved experimental bandwidths as high as 141%. The pulse-echo responses displayed good agreement with modeled results using the Redwood equivalent circuit.

Cellular immune response against tropomyosin isoform 5 in ulcerative colitis

We have reported an autoantibody response in ulcerative colitis (UC) against human tropomyosin isoform 5 (hTM5), the predominant colonic epithelial cell hTM isoform. In this report, we determined the number of IFN-gamma-secreting cells (spot-forming cells, SFC) against hTM5 by an enzyme-linked immunospot (ELISPOT) assay. Another cytoskeletal protein, caldesmon, CaD40, was used as a control antigen. Peripheral blood mononuclear cells were separated by a Ficoll density gradient from 28 patients with UC, 13 patients with Crohn's disease (CD), and 9 healthy subjects (HS). The mean (+/-SEM) SFC values against hTM5 in UC, CD, and HS were 48.8 +/- 8.1, 18.6 +/- 4.6, and 20.8 +/- 8.6, respectively. The value in UC was significantly higher than those in CD (P < 0.005) and HS (P < 0.025). SFC values in CD did not differ from those in HS. None of the 50 samples (except 1 UC) reacted to the CaD40 antigen. This study demonstrates, for the first time, a defined colon epithelial cell antigen, hTM5, that is capable of inducing a significant T cell response in UC but not in CD.

Synthesis of highly potent second-generation taxoids through effective kinetic resolution coupling of racemic beta-lactams with baccatins

A series of highly potent second-generation taxoids bearing a 2-methylprop-1-enyl or a 2-methylpropyl group at C-3' with modifications at the C-2, C-10, and C-14 positions was synthesized through the coupling of racemic cis-beta-lactams with properly protected/modified baccatin and 14-OH-baccatin. A high level of kinetic resolution was observed for all cases examined. The observed highly efficient enantiomer differentiation is ascribed to the markedly different chiral environment between the (+)- and (-)-beta-lactams in their approach to the chiral framework of the enantiopure lithium alkoxide of a baccatin in the ring-opening coupling process. It was also observed that substantially higher selectivity was achieved when 14-OH-baccatin-1,14-carbonate was used. Analysis of the transition state models revealed that the repulsive interactions between the 3-TIPS group of a (-)-beta-lactam with 1, 14-carbonate group of the baccatin substantially increases the asymmetric bias in the kinetic resolution process, favoring the reaction of a (+)-beta-lactam, which leads to the observed excellent selectivity.