Two distinct secretory vesicle-priming steps in adrenal chromaffin cells

The calcium-dependent activator proteins for secretion, CAPS1 and CAPS2, facilitate syntaxin opening during synaptic vesicle priming.

Priming of large dense-core vesicles (LDCVs) is a Ca²⁺-dependent step by which LDCVs enter a release-ready pool, involving the formation of the soluble N-ethyl-maleimide sensitive fusion protein attachment protein (SNAP) receptor complex consisting of syntaxin, SNAP-25, and synaptobrevin. Using mice lacking both isoforms of the calcium-dependent activator protein for secretion (CAPS), we show that LDCV priming in adrenal chromaffin cells entails two distinct steps. CAPS is required for priming of the readily releasable LDCV pool and sustained secretion in the continued presence of high Ca²⁺ concentrations. Either CAPS1 or CAPS2 can rescue secretion in cells lacking both CAPS isoforms. Furthermore, the deficit in the readily releasable LDCV pool resulting from CAPS deletion is reversed by a constitutively open form of syntaxin but not by Munc13-1, a priming protein that facilitates the conversion of syntaxin to the open conformation. Our data indicate that CAPS functions downstream of Munc13s but also interacts functionally with Munc13s in the LDCV-priming process.

Phase II study of a triplet regimen of S-1 combined with irinotecan and oxaliplatin in patients with metastatic gastric cancer: clinical and pharmacogenetic results

BACKGROUND

The aim of this study was to investigate the efficacy and safety of S-1/irinotecan/oxaliplatin (TIROX) in metastatic gastric cancer (MGC) and the association between treatment outcome and uridine diphosphate-glucuronosyltransferase (UGT) 1A polymorphisms.

PATIENTS AND METHODS

Patients with previously untreated MGC received S-1 40 mg/m(2) b.i.d. on days 1-14 and irinotecan 150 mg/m(2) plus oxaliplatin 85 mg/m(2) on day 1 every 3 weeks.

RESULTS

Forty-four patients were enrolled. In intent-to-treat analysis, the objective response rate was 75%, including the complete response (CR) rate of 14%. The median time to progression and overall survival was 10.2 and 17.6 months, respectively. Ten (26%) of the 39 patients with primary gastric tumor showed biopsy-confirmed gastric CR. Grade 3/4 neutropenia developed in 66% of patients and grade 3 febrile neutropenia in 16%. The most common grade 3 nonhematologic toxic effects were abdominal pain (18%), anorexia (16%), and diarrhea (14%). UGT1A polymorphisms were associated with significantly higher incidence of grade 4 leukopenia (UGT1A1*6), neutropenia (UGT1A1*6, UGT1A6*2, and UGT1A7*3), grade 3/4 febrile neutropenia (UGT1A1*6), and grade 3 abdominal pain (UGT1A1*6).

CONCLUSIONS

The TIROX regimen induced marked tumor reduction and promising survival with a manageable toxicity profile in MGC patients. UGT1A genotype may be predictive of TIROX toxicity.

Regulation of Rap2A by the ubiquitin ligase Nedd4-1 controls neurite development

Nedd4-1 is a "neuronal precursor cell expressed and developmentally downregulated protein" and among the most abundant E3 ubiquitin ligases in mammalian neurons. In analyses of conventional and conditional Nedd4-1-deficient mice, we found that Nedd4-1 plays a critical role in dendrite formation. Nedd4-1, the serine/threonine kinase TNIK, and Rap2A form a complex that controls Nedd4-1-mediated ubiquitination of Rap2A. Ubiquitination by Nedd4-1 inhibits Rap2A function, which reduces the activity of Rap2 effector kinases of the TNIK family and promotes dendrite growth. We conclude that a Nedd4-1/Rap2A/TNIK signaling pathway regulates neurite growth and arborization in mammalian neurons.

Does triple-negative breast cancer (TNBC) have distinct clinicopathologic characteristics and prognostic significance?

21088

Background: Studies have suggested that TNBC, defined by estrogen receptor-negative, progesterone receptor-negative, and HER2-negative, may represent the subset of breast cancer(BC) with different biologic behavior. Here we investigated the clinicopathologic characteristics of TNBC and its prognostic significance in Korean BC patients. Methods: Patients diagnosed as invasive BC and underwent curative surgery at Seoul National University Hospital between Jan. 2000 and Jun. 2003, were reviewed, retrospectively. We excluded the patients whose immunohistochemistry for hormone receptor nor HER2 status had not been evaluated, and who had been treated with adjuvant trastuzumab or neoadjuvant chemotherapy (CT). Clinicopathologic variables (age, T and N stage, endovascular or lymphatic tumor emboli, nuclear and histologic grade, p53, bcl2, Ki67) and 3 year relapse free survival (3YRFS) rate of TNBC were compared with those of non- TNBC. Results: 1,136 patients were eligible for analysis. The median follow-up was 48.7 months. 341 patients underwent breast conserving surgery followed by adjuvant radiotherapy. 249 patients were TNBC and 62.1% of those were node negative. 86.4% of node negative TNBC, 88.3% of node positive TNBC, 53.9% of node negative non-TNBC, and 90.2% of node positive non-TNBC received adjuvant CT. Compared with non-TNBC, TNBC was correlated with younger age (age<35,14.1% vs. 8.2%, p=0.013), higher nuclear and histologic grade(62.2% vs. 23.6%, p=0.001;60.2% vs. 24.6%, p=0.001, respectively); positive staining for p53 (p=0.001) and higher positivity for Ki67 (p=0.001), suggesting the biologic aggressiveness of TNBC. During the follow-up periods, 17.3% of TNBC were relapsed. In particular, 3YRFS in node negative TNBC and non-TNBC were 86% and 96%, respectively (p<0.001). But, in node positive BC, 3YRFS was not different between TNBC and non-TNBC (80.6% vs. 83%, p=0.99). Conclusions: We confirm that TNBC shows more aggressive clinicopathologic characteristics and in particular, higher relapse in node negative BC. Thus, triple-negativity(TN) may be integrated into risk factor analysis in node negative BC. Final results of more detailed molecular analysis for TNBC would be available in the meeting.

No significant financial relationships to disclose.

Multiplexed genotyping using a novel digitally inscribed bead-based system

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Background: Genotyping of clinical samples has been limited to low levels of multiplexing, ranging from one to a few dozen single nucleotide polymorphisms (SNPs) per sample. By increasing multiplexing levels, a clinical lab can increase information content per sample, decreasing costs and sample material requirements. Methods: We have adapted the GoldenGate® Assay for simultaneously genotyping 96 to 1,536 SNPs to the BeadXpress™ System, a new high-throughput platform that utilizes digitally inscribed VeraCode™ beads in a compact fluidic instrument. Genotyping on this platform ranges from 96 to 384 multiplexing, using the same GoldenGate Assay that has proven highly robust for millions of genotypes. In preliminary tests, we have observed greater than 99% call rates, and greater than 99.5% rates for reproducibility and heritability. In a test of 96 SNP genotypes chosen for a study of colorectal cancer, a point mutation in the MSH2 gene, previously implicated in predisposition to several cancers, was correctly genotyped when compared to qPCR analysis of the same samples. Conclusion: Together with genotyping data from reference samples, the GoldenGate Assay on the BeadXpress System has yielded highly reproducible and accurate genotypes, suggesting that this approach will prove useful for rapid refinement of SNPs for development of clinical genotyping tests.

No significant financial relationships to disclose.

Effect of acute acoustic stress on anorectal function sensation in healthy human

Little is known about the effects of acute acoustic stress on anorectal function. To determine the effects of acute acoustic stress on anorectal function and sensation in healthy volunteers. Ten healthy volunteers (7 M, 3 F, mean age 34 +/- 3 years) underwent anorectal manometry, testing of rectal compliance and sensation using a barostat with and without acute noise stress on separate days. Rectal perception was assessed using an ascending method of limits protocol and a 5-point Likert scale. Arousal and anxiety status were evaluated using a visual analogue scale. Acoustic stress significantly increased anxiety score (P < 0.05). Rectal compliance was significantly decreased with acoustic stress compared with control P (P < 0.000001). In addition, less intraballoon volume was needed to induce the sensation of severe urgency with acoustic stress (P < 0.05). Acoustic stress had no effect on hemodynamic parameters, anal sphincter pressure, threshold for first sensation, sensation of stool, or pain. Acute acoustic stimulation increased anxiety scores, decreased rectal compliance, and enhanced perception of severe urgency to balloon distention but did not affect anal sphincter pressure in healthy volunteers. These results may offer insight into the pathogenesis of stress-in-induced diarrhoea and faecal urgency.

Endovascular stent graft selection for the treatment of abdominal aortic aneurysms

Minimally invasive endovascular techniques for the treatment of abdominal aortic aneurysms (AAA) have significantly reduced the morbidity of these procedures as compared with standard surgical repair. In addition, patients with extensive comorbid medical illnesses in whom standard operative repair is contra-indicated, may be successfully treated using endovascular means. A variety of endovascular stent grafts are currently being used clinically for endovascular AAA repair. The characteristics of these stent grafts vary significantly. In selecting the specific stent graft to be used for endovascular AAA repair, these specific characteristics must be considered particularly with regard to the individual patient's anatomic and physiologic characteristics. The United States Food and Drug Administration (FDA) has approved 4 endovascular stent grafts for the treatment of AAA: the Medtronic AneuRx, the W. L. Gore Excluder, the Cook Zenith and the Guidant Ancure. The Zenith graft received approval for marketing in 2003 and has gained relatively wide usage, in part due to its ability to treat aneurysms with relatively large diameter implantations zones. Also in 2003 the Guidant Corporation withdrew the Ancure graft from marketing and distribution. Enrollment has also been recently completed for the phase II FDA trials of the Medtronic Talent graft and the Cordis Fortron graft. These devices have been approved for use in the European Union and are awaiting FDA panel meeting in the United States. Comparative analysis of several of the available stent grafts has been performed. Results have varied with regard to the need for secondary interventions, aneurysm sac size reduction and the occurrence of continued perfusion of the aneurysm sac. Several significant advances have also occurred recently in stent graft research and development. Of particular significance has been the initiation of the phase I trial of the Trivascular Enovus graft. Deployment of the Trivascular graft may be accomplished through a delivery system that is considerably reduced in profile. The potential for percutaneous application of the graft may be available in the future. The indications for use of endovascular grafts as compared to standard open surgery have not yet been fully defined. Endovascular stent grafts in current use have limitations and their use must be tempered accordingly, until their long-term effectiveness is more completely evaluated. This article describes the general principles of use for endovascular devices for the repair of AAAs. It details the features and results for the devices in current use and highlights the factors that influence the selection of specific stent graft types.

Cognitive resources during sentence processing in Alzheimer's disease

This study assessed sentence comprehension in Alzheimer's disease (AD) while minimizing executive resource demands. AD patients (n=17) and healthy elderly control subjects (n=17) were asked to detect a word in a sentence. Unbeknownst to subjects, the target word at times followed an incorrect grammatical or semantic agreement. Control subjects took significantly longer to respond to a target word when it immediately followed an agreement violation compared to a coherent agreement, a difference that was not evident when the target word followed the agreement by several syllables. AD patients did not demonstrate a discrepancy between a violation and a coherent agreement in the immediate vicinity of the agreement, but demonstrated a significant delay in their response to a target word when it followed an agreement violation--particularly a violation of a grammatical agreement--by several syllables. Analyses of individual patient performance profiles revealed the pattern of delayed sensitivity to agreements in a majority of AD patients. Correlation and regression analyses associated AD patients' sensitivity to agreement violations over an abnormally delayed time course with a measure of inhibitory control, although weaker associations were also evident with measures of planning and short-term memory. We hypothesize that difficulty understanding grammatically complex sentences in AD is related to slowed information processing speed that restricts the timely construction of a sentence's structure and limits inhibition of canonical sentence interpretations such as first-noun-is-subject.

Inductive reasoning in Alzheimer's disease

We evaluated knowledge of basic level and superordinate semantic relations and the role of cognitive resources during inductive reasoning in probable Alzheimer's disease (AD). Nineteen mildly demented AD patients and 17 healthy control subjects judged the truthfulness of arguments with a premise and a conclusion that contain familiar concepts coupled with "blank" predicates, such as "Spiders contain phosphatidylcholine; therefore all insects contain phosphatidylcholine." Like healthy control subjects, AD patients were relatively insensitive to the typicality of the premise category when judging the strength of arguments with a conclusion containing a basic-level concept, but were relatively sensitive to typicality during judgments of arguments containing a superordinate in the conclusion. Moreover, AD patients resembled control subjects in judging arguments with an immediate superordinate in the conclusion compared to arguments with a distant superordinate. AD patients differed from control subjects because they could not take advantage of two premises in an argument containing basic-level concepts. We conclude that semantic knowledge is sufficiently preserved in AD to support inductive reasoning, but that limited cognitive resources may interfere with AD patients' ability to consider the entire spectrum of information available during semantic challenges.

Cytokine stimulation of energy expenditure through p38 MAP kinase activation of PPARgamma coactivator-1

Cachexia is a chronic state of negative energy balance and muscle wasting that is a severe complication of cancer and chronic infection. While cytokines such as IL-1alpha, IL-1beta, and TNFalpha can mediate cachectic states, how these molecules affect energy expenditure is unknown. We show here that many cytokines activate the transcriptional PPAR gamma coactivator-1 (PGC-1) through phosphorylation by p38 kinase, resulting in stabilization and activation of PGC-1 protein. Cytokine or lipopolysaccharide (LPS)-induced activation of PGC-1 in cultured muscle cells or muscle in vivo causes increased respiration and expression of genes linked to mitochondrial uncoupling and energy expenditure. These data illustrate a direct thermogenic action of cytokines and p38 MAP kinase through the transcriptional coactivator PGC-1.

Control of hepatic gluconeogenesis through the transcriptional coactivator PGC-1

Blood glucose levels are maintained by the balance between glucose uptake by peripheral tissues and glucose secretion by the liver. Gluconeogenesis is strongly stimulated during fasting and is aberrantly activated in diabetes mellitus. Here we show that the transcriptional coactivator PGC-1 is strongly induced in liver in fasting mice and in three mouse models of insulin action deficiency: streptozotocin-induced diabetes, ob/ob genotype and liver insulin-receptor knockout. PGC-1 is induced synergistically in primary liver cultures by cyclic AMP and glucocorticoids. Adenoviral-mediated expression of PGC-1 in hepatocytes in culture or in vivo strongly activates an entire programme of key gluconeogenic enzymes, including phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase, leading to increased glucose output. Full transcriptional activation of the PEPCK promoter requires coactivation of the glucocorticoid receptor and the liver-enriched transcription factor HNF-4alpha (hepatic nuclear factor-4alpha) by PGC-1. These results implicate PGC-1 as a key modulator of hepatic gluconeogenesis and as a central target of the insulin-cAMP axis in liver.

The Hox cofactor and proto-oncogene Pbx1 is required for maintenance of definitive hematopoiesis in the fetal liver

Pbx1 is the product of a proto-oncogene originally discovered at the site of chromosomal translocations in acute leukemias. It binds DNA as a complex with a broad subset of homeodomain proteins, but its contributions to hematopoiesis have not been established. This paper reports that Pbx1 is expressed in hematopoietic progenitors during murine embryonic development and that its absence results in severe anemia and embryonic lethality at embryonic day 15 (E15) or E16. Definitive myeloerythroid lineages are present in Pbx1(-/-) fetal livers, but the total numbers of colony-forming cells are substantially reduced. Fetal liver hypoplasia reflects quantitative as well as qualitative defects in the most primitive multilineage progenitors and their lineage-restricted progeny. Hematopoietic stem cells from Pbx1(-/-) embryos have reduced colony-forming activity and are unable to establish multilineage hematopoiesis in competitive reconstitution experiments. Common myeloid progenitors (CMPs), the earliest known myeloerythroid-restricted progenitors, are markedly depleted in Pbx1(-/-) embryos at E14 and display clonogenic defects in erythroid colony formation. Comparative cell-cycle indexes suggest that these defects result largely from insufficient proliferation. Megakaryocyte- and erythrocyte-committed progenitors are also reduced in number and show decreased erythroid colony-forming potential. Taken together, these data indicate that Pbx1 is essential for the function of hematopoietic progenitors with erythropoietic potential and that its loss creates a proliferative constriction at the level of the CMP. Thus, Pbx1 is required for the maintenance, but not the initiation, of definitive hematopoiesis and contributes to the mitotic amplifications of progenitor subsets through which mature erythrocytes are generated. (Blood. 2001;98:618-626)

Synthesis and in vitro antibacterial activity of cephalosporins with a pyridinium substituent carrying an isoxazole moiety at the C-3 position

Several quaternary pyridinium cephalosporin analogues were prepared and evaluated in vitro for antibacterial activity against selected gram-positive and gram-negative organisms. Most of the synthesized analogues were either as effective or less effective against the tested bacterial organisms than the reference compounds, Cefpirome and Ceftazidime.

Essential tyrosine residues for interaction of the non-receptor protein-tyrosine phosphatase PTP1B with N-cadherin

Expression of a dominant-negative, catalytically inactive form of the nonreceptor protein-tyrosine phosphatase PTP1B in L-cells constitutively expressing N-cadherin results in loss of N-cadherin-mediated cell-cell adhesion. PTP1B interacts directly with the cytoplasmic domain of N-cadherin, and this association is regulated by phosphorylation of tyrosine residues in PTP1B. The following three tyrosine residues in PTP1B are potential substrates for tyrosine kinases: Tyr-66, Tyr-152, and Tyr-153. To determine the tyrosine residue(s) that are crucial for the cadherin-PTP1B interaction we used site-directed mutagenesis to create catalytically inactive PTP1B constructs bearing additional single, double, or triple mutations in which tyrosine was substituted by phenylalanine. Mutation Y152F eliminates binding to N-cadherin in vitro, whereas mutations Y66F and Y153F do not. Overexpression of the catalytically inactive PTP1B with the Y152F mutation in L-cells constitutively expressing N-cadherin has no effect on N-cadherin-mediated adhesion, and immunoprecipitation reveals that the mutant Y152F PTP1B does not associate with N-cadherin in situ. Furthermore, among cells overexpressing the Y152F mutant endogenous PTP1B associates with N-cadherin and is tyrosine-phosphorylated.