bluuebunny/crossref_metadata_2025 huggingface dataset:
Vascular cell adhesion molecule 1 (VCAM-1) activation of endothelial cell matrix metalloproteinases: role of reactive oxygen species
Authors: Deem Tracy L. , Cook-Mills Joan M.
Published: July 2004

Lymphocytes bound at endothelial cell junctions extravasate within minutes. Lymphocyte-endothelial cell binding is mediated by receptors such as vascular cell adhesion molecule 1 (VCAM-1). VCAM-1 activates endothelial cell nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in minutes, and this activity is required for VCAM-1–dependent lymphocyte migration. In this report, we examined mechanisms for activation of matrix metalloproteinases (MMPs) during VCAM-1–dependent lymphocyte migration. Lymphocyte binding to VCAM-1 rapidly activated endothelial cell-associated MMPs. Furthermore, inhibition of MMPs on the endothelial cells but not on the lymphocytes blocked VCAM-1–dependent lymphocyte migration across endothelial cells. The activation of endothelial cell MMPs required VCAM-1–stimulated endothelial cell NADPH oxidase activity as determined by scavenging of reactive oxygen species (ROS) and by pharmacologic or antisense inhibition of NADPH oxidase. Exogenous addition of 1 μM H2O2, the level of H2O2 generated by VCAM-1–stimulated endothelial cells, rapidly activated endothelial cell-associated MMPs. In contrast, activation of lymphocyte-associated MMPs was delayed by hours after binding to VCAM-1, and this activation was blocked by inhibition of endothelial cell ROS generation. There was also a delay in H2O2-induced decrease in lymphocyte-associated tissue inhibitors of metalloproteinases (TIMPs), resulting in an increase in MMP/TIMP ratio. In summary, this is the first report of a mechanism for ROS function in VCAM-1 activation of endothelial cell MMPs during VCAM-1–dependent lymphocyte migration.
Differences in the chromatin structure and cis-element organization of the human and mouse GATA1 loci: implications for cis-element identification
Authors: Valverde-Garduno Veronica , Guyot Boris , Anguita Eduardo , Hamlett Isla , Porcher Catherine , Vyas Paresh
Published: July 2004

Cis-element identification is a prerequisite to understand transcriptional regulation of gene loci. From analysis of a limited number of conserved gene loci, sequence comparison has proved a robust and efficient way to locate cis-elements. Human and mouse GATA1 genes encode a critical hematopoietic transcription factor conserved in expression and function. Proper control of GATA1 transcription is critical in regulating myeloid lineage specification and maturation. Here, we compared sequence and systematically mapped position of DNase I hypersensitive sites, acetylation status of histone H3/H4, and in vivo binding of transcription factors over approximately 120 kilobases flanking the human GATA1 gene and the corresponding region in mice. Despite lying in approximately 10 megabase (Mb) conserved syntenic segment, the chromatin structures of the 2 homologous loci are strikingly different. The 2 previously unidentified hematopoietic cis-elements, one in each species, are not conserved in position and sequence and have enhancer activity in erythroid cells. In vivo, they both bind the transcription factors GATA1, SCL, LMO2, and Ldb1. More broadly, there are both species- and regulatory element–specific patterns of transcription factor binding. These findings suggest that some cis-elements regulating human and mouse GATA1 genes differ. More generally, mouse human sequence comparison may fail to identify all cis-elements.
Reduced pigmentation (rp), a mouse model of Hermansky-Pudlak syndrome, encodes a novel component of the BLOC-1 complex
Authors: Gwynn Babette , Martina Jose A. , Bonifacino Juan S. , Sviderskaya Elena V. , Lamoreux M. Lynn , Bennett Dorothy C. , Moriyama Kengo , Huizing Marjan , Helip-Wooley Amanda , Gahl William A. , Webb Lisa S. , Lambert Amy J. , Peters Luanne L.
Published: July 2004

Hermansky-Pudlak syndrome (HPS), a disorder of organelle biogenesis, affects lysosomes, melanosomes, and platelet dense bodies. Seven genes cause HPS in humans (HPS1-HPS7) and at least 15 nonallelic mutations cause HPS in mice. Where their function is known, the HPS proteins participate in protein trafficking and vesicle docking/fusion events during organelle biogenesis. HPS-associated genes participate in at least 4 distinct protein complexes: the adaptor complex AP-3; biogenesis of lysosome-related organelles complex 1 (BLOC-1), consisting of 4 HPS proteins (pallidin, muted, cappuccino, HPS7/sandy); BLOC-2, consisting of HPS6/ruby-eye, HPS5/ruby-eye-2, and HPS3/cocoa; and BLOC-3, consisting of HPS1/pale ear and HPS4/light ear. Here, we report the cloning of the mouse HPS mutation reduced pigmentation (rp). We show that the wild-type rp gene encodes a novel, widely expressed 195-amino acid protein that shares 87% amino acid identity with its human orthologue and localizes to punctate cytoplasmic structures. Further, we show that phosphorylated RP is part of the BLOC-1 complex. In mutant rp/rp mice, a premature stop codon truncates the protein after 79 amino acids. Defects in all the 5 known components of BLOC-1, including RP, cause severe HPS in mice, suggesting that the subunits are nonredundant and that BLOC-1 plays a key role in organelle biogenesis.
pRb, Myc and p53 are critically involved in SV40 large T antigen repression of PDGF β-receptor transcription
Authors: Uramoto Hidetaka , Hackzell Anders , Wetterskog Daniel , Ballági Andrea , Izumi Hiroto , Funa Keiko
Published: July 2004

The expression of the PDGF β-receptor is tightly regulated during a normal cell cycle. c-Myc and p73α repress transcription of the receptor through interaction with NF-Y. In ST15A cells which stably express the temperature-sensitive SV40 large T antigen (LT) the receptor expression and ligand binding decreased under the permissive condition. Transient expression of the LT, but not small t, decreased the endogenous receptor expression at mRNA and protein levels in NIH3T3 cells but not in the myc-null HO15.19 cells. The wild-type LT, but not the various pRb or p53 binding defective LT mutants, represses the PDGF β-receptor promoter activity. Moreover, the inability of the LT-mediated repression in the myc-null cells, the Rb-null 3T3 cells, and the Saos-2 cells lacking pRb and p53, indicates that Myc, pRb and p53 are all necessary elements. PDGF β-receptor promoter-luciferase assays revealed that the CCAAT motif is important for the repression. Furthermore, p53 was found to increase the promoter activity mainly via the upstream Sp1 binding sites together with the CCAAT motif in the NIH 3T3 cells. This was confirmed by Schneider's Drosophila line (SL2) cells deficient in both endogenous NF-Y and Sp1. Chromatin immunoprecipitation using ST15A cells revealed that both LT and p53 bound the PDGF β-receptor promoter and the binding of p53 diminished when LT was expressed in the permissive condition. However, LT binds the promoter in the absence of pRb and p53 in Saos-2 cells stably expressing LT. These results suggest that LT binds the promoter and interferes with NF-Y and Sp1 to repress it in the presence of Myc, pRb and p53.
Continuous phosphatidylinositol metabolism is required for cleavage of crane fly spermatocytes
Authors: Saul Daniel , Fabian Lacramioara , Forer Arthur , Brill Julie A.
Published: July 2004

Successful cleavage of animal cells requires co-ordinated regulation of the actomyosin contractile ring and cleavage furrow ingression. Data from a variety of systems implicate phosphoinositol lipids and calcium release as potential regulators of this fundamental process. Here we examine the requirement for various steps of the phosphatidylinositol (PtdIns) cycle in dividing crane fly (Nephrotoma suturalis) spermatocytes. PtdIns cycle inhibitors were added to living cells after cleavage furrows formed and began to ingress. Inhibitors known to block PtdIns recycling (lithium), PtdIns phosphorylation (wortmannin, LY294002) or phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] hydrolysis [U73122 (U7)] all stopped or slowed furrowing. The effect of these drugs on cytokinesis was quite rapid (within 0-4 minutes), so continuous metabolism of PtdIns appears to be required for continued cleavage furrow ingression. U7 caused cleavage furrow regression concomitant with depletion of F-actin from the contractile ring, whereas the other inhibitors caused neither regression nor depletion of F-actin. That U7 depletes furrow-associated actin seems counterintuitive, as inhibition of phospholipase C would be expected to increase cellular levels of PtdIns(4,5)P2 and hence increase actin polymerization. Our confocal images suggest, however, that F-actin might accumulate at the poles of U7-treated cells, consistent with the idea that PtdIns(4,5)P2 hydrolysis may be required for actin filaments formed at the poles to participate in contractile ring assembly at the furrow.
The yeast dynamin-related GTPase Vps1p functions in the organization of the actin cytoskeleton via interaction with Sla1p
Authors: Yu Xianwen , Cai Mingjie
Published: July 2004

Recent studies have suggested that the function of the large GTPase dynamin in endocytosis in mammalian cells may comprise a modulation of actin cytoskeleton. The role of dynamin in actin cytoskeleton organization in the yeast Saccharomyces cerevisiae has remained undefined. In this report, we found that one of the yeast dynamin-related proteins, Vps1p, is required for normal actin cytoskeleton organization. At both permissive and non-permissive temperatures, the vps1 mutants exhibited various degrees of phenotypes commonly associated with actin cytoskeleton defects: depolarized and aggregated actin structures, hypersensitivity to the actin cytoskeleton toxin latrunculin-A, randomized bud site selection and chitin deposition, and impaired efficiency in the internalization of membrane receptors. Over-expression of the GTPase mutants of vps1 also led to actin abnormalities. Consistent with these actin-related defects, Vps1p was found to interact physically, and partially co-localize, with the actin-regulatory protein Sla1p. The normal cellular localization of Sla1p required Vps1p and could be altered by over-expression of a region of Vps1p that was involved in the interaction with Sla1p. The same region also promoted mis-sorting of the vacuolar protein carboxypeptidase Y upon over-expression. These findings suggest that the functions of the dynamin-related protein Vps1p in actin cytoskeleton dynamics and vacuolar protein sorting are probably related to each other.
The Clp1p/Flp1p phosphatase ensures completion of cytokinesis in response to minor perturbation of the cell division machinery inSchizosaccharomyces pombe
Authors: Mishra Mithilesh , Karagiannis Jim , Trautmann Susanne , Wang Hongyan , McCollum Dannel , Balasubramanian Mohan K.
Published: July 2004

Fission yeast mutants defective in actomyosin ring formation and function exhibit a prolonged G2 delay following cytokinesis failure. This G2 delay depends on the SIN, a signaling network essential for cytokinesis, and the non-essential Cdc14p family phosphatase, Clp1p/Flp1p and has been proposed to signify a cytokinesis checkpoint mechanism. However, the physiological relevance of this proposed Clp1p/Flp1p-dependent checkpoint is unclear because all previous studies were carried out using mutations in essential actomyosin ring components under fully restrictive conditions and thus these cells would have died regardless of the presence of the checkpoint. Here we show that delays in cytokinesis caused by minor perturbations to different components of the cytokinetic machinery, which normally cause only mild defects, become lethal when Clp1p/Flp1p is inactivated. In addition, we show that Clp1p/Flp1p does not function simply to inhibit further rounds of nuclear division, but also allows damaged actomyosin rings to be maintained to facilitate completion of cell division. Ectopic activation of the SIN significantly bypasses the requirement of Clp1p/Flp1p for G2 delay as well as for completion of cytokinesis. We conclude that the Clp1p/Flp1p-dependent cytokinesis checkpoint provides a previously unrecognized cell survival advantage when the cell division apparatus is mildly perturbed.
Analysis ofChlamydia caviaeentry sites and involvement of Cdc42 and Rac activity
Authors: Subtil Agathe , Wyplosz Benjamin , Balañá María Eugenia , Dautry-Varsat Alice
Published: July 2004

In epithelial cells, endocytic activity is mostly dedicated to nutrient and macromolecule uptake. To invade these cells, Chlamydiaceae, like other pathogens, have evolved strategies that utilise the existing endocytic machineries and signalling pathways, but little is known about the host cell molecules involved. In this report, we show that within five minutes of infection of HeLa cells by Chlamydia caviae GPIC strain several events take place in the immediate vicinity of invasive bacteria: GM1-containing microdomains cluster, tyrosine-phosphorylated proteins accumulate, and intense actin polymerization occurs. We show that actin polymerization is controlled by the small GTPases Cdc42 and Rac, which become activated upon infection. Expression of dominant negative forms of these GTPases inhibits C. caviae entry and leads to abnormal actin polymerization. In contrast, the small GTPase Rho does not seem essential for bacterial entry. Finally, phosphatidylinositol 3-kinase activity is also required for internalization of C. caviae, probably downstream of the other molecular events reported here. We present the first scheme of the events occurring at the sites of invasion of epithelial cells by a member of the Chlamydiaceae family.
Nucleolar localization of the human telomeric repeat binding factor 2 (TRF2)
Authors: Zhang Suisheng , Hemmerich Peter , Grosse Frank
Published: July 2004

The telomeric repeat binding factor 2 (TRF2) specifically recognizes TTAGGG tandem repeats at chromosomal ends. Unexpectedly immunofluorescence studies revealed a prominent nucleolar localization of TRF2 in human cells, which appeared as discrete dots with sizes similar to those present in the nucleoplasm. The TRF2 dots did not overlap with dots stemming from the upstream binding factor (UBF) or the B23 protein. After treatment with a low concentration of actinomycin D (0.05 μg/ml), TRF2 remained in the nucleolus, although this condition selectively inhibited RNA polymerase I and led to a relocalization of UBF and B23. TRF2 was prominent in the nucleolus at G0 and S but seemed to diffuse out of the nucleolus in G2 phase. During mitosis TRF2 dispersed from the condensed chromosomes and returned to the nucleolus at cytokinesis. Treatment with low doses of actinomycin D delayed the release of TRF2 from the nucleolus as cells progressed from G2 phase into mitosis. With actinomycin D present TRF2 was detected in discrete foci adjacent to UBF in prophase, while in metaphase a complete overlap between TRF2 and UBF was observed. TRF2 was present in DNase-insensitive complexes of nucleolar extracts, whereas DNA degradation disrupted the protein-DNA complexes consisting of Ku antigen and B23. Following treatment with actinomycin D some of the mitotic cells displayed chromosome end-to-end fusions. This could be correlated to the actinomycin D-suppressed relocalization of TRF2 from the nucleolus to the telomeres during mitosis. These results support the view that the nucleolus may sequester TRF2 and thereby influences its telomeric functions.
DNA replication and transcription direct a DNA strand bias in the process of targeted gene repair in mammalian cells
Authors: Brachman Erin E. , Kmiec Eric B.
Published: July 2004

The repair of point mutations can be directed by modified single-stranded DNA oligonucleotides and regulated by cellular activities including homologous recombination, mismatch repair and transcription. Now, we report that DNA replication modulates the gene repair process by influencing the frequency with which either DNA strand is corrected. An SV40-virus-based system was used to investigate the role of DNA synthesis on gene repair in COS-1 cells. We confirm that transcription exerts a strand bias on the gene repair process even when correction takes place on actively replicating templates. We were able to distinguish between the influences of transcription and replication on strand bias by changing the orientation of a gene encoding enhanced green fluorescent protein relative to the origin of replication, and confirmed the previously observed bias towards the untranscribed strand. We report that DNA replication can increase the level of untranscribed strand preference only if that strand also serves as the lagging strand in DNA synthesis. Furthermore, the effect of replication on gene repair frequency and strand bias appears to be independent of certain mismatched base pairs and oligonucleotide length.
Evaluation of σ-Donating Ability of a 9-Phosphatriptycene and Its Application to Catalytic Reactions
Authors: Agou Tomohiro , Kobayashi Junji , Kawashima Takayuki
Published: July 2004

The low σ-donating ability of 9-phosphatriptycene 1 was revealed by cyclic voltammetry and theoretical calculations. The tungsten complex of 1 was synthesized and the IR and NMR spectroscopic data of the complex also suggested the low σ-donating ability of 1. 1 was shown to be effective as a ligand in the palladium-catalyzed reactions, the Stille coupling and the Heck reaction.
A Novel Synthesis of syn and anti β-Hydroxy Dithioacetals, Masked Cross-Aldols between Aldehydes
Authors: Saitoh Terunobu , Jimbo Naohisa , Ichikawa Junji
Published: July 2004

Ketene dithioacetals readily reacted with aldehydes in the presence of a Lewis acid such as BF3·OEt2 or TMSOTf to generate the cationic adducts, which in turn reacted with NaAlH2(OCH2CH2OCH3)2, leading to the corresponding β-hydroxy dithioacetals, masked cross-aldols between aldehydes. Each diastereomer was selectively obtained by choosing the appropriate Lewis acid and substituents on the sulfur atoms of the ketene dithioacetals.
Regeneration of Carbonyl Compounds from Oximes Using BTBAD under Microwave Irradiation
Authors: Murugan R , Reddy B S R
Published: July 2004

Bis-tetrabutylammonium dichromate (BTBAD) has been found to be an efficient and new reagent for the conversion of oximes to the corresponding carbonyl compounds. The reaction was performed under microwave irradiation and gave excellent yields. It also facilitates the de-protection of acetals and ketals.
Performance Enhancement by Blending an Electron Acceptor in TiO2/polyphenylenevinylene/Au Solid-state Solar Cells
Authors: Takahashi Kohshin , Seto Kaname , Yamaguchi Takahiro , Nakamura Jun-ichi , Yokoe Chiho , Murata Kazuhiko
Published: July 2004

When an electron acceptor, [2-[2-[4-(dimethylamino)phenyl]ethenyl]-6-methyl-4H-pyran-4-ylidene]propanedinitrile (DCM) was blended into poly[2-methoxy-5-(2′-ethylenehexyloxy)-1,4-phenylenevinylene] (MEH-PPV) in a TiO2/MEH-PPV/Au sandwich-type solar cell, the cell performance was remarkably enhanced, resulting in 0.47% of energy conversion yield under the irradiation of AM 1.5–100 mW/cm2.
Growth Hormone Use in Children with Idiopathic Short Stature
Authors: Weise Karen L , Nahata Milap C
Published: July 2004

OBJECTIVE:

To review the indication, pharmacology, pharmacokinetics, efficacy, and adverse effects of recombinant human growth hormone in children with idiopathic short stature (ISS).

DATA SOURCES:

A MEDLINE search (1966–December 2003) was performed using the key words human growth hormone, somatropin, Humatrope, normal children, somatrem, and idiopathic short stature. Food and Drug Administration Advisory Committee Meeting minutes were also reviewed.

STUDY SELECTION AND DATA EXTRACTION:

The data presented in this review were obtained from published literature, abstracts presented at scientific meetings, and information on file with the manufacturer. Additional articles from these sources were also identified. Current issues of pediatric and endocrinology journals were reviewed for the most recent articles. Articles only addressing the use of growth hormone in normal, healthy children were used.

DATA SYNTHESIS:

Somatropin is indicated for use in children with ISS. Studies have shown modest benefit to final height achieved and, at the doses used for ISS, there have been no adverse effects associated with somatropin. Many questions still exist, however, concerning the most appropriate age to initiate treatment and duration of treatment. There are also many ethical concerns surrounding patient selection criteria and potential for increased off-label use.

CONCLUSIONS:

Growth hormone has been found to have modest efficacy in improving final height in children with ISS. The specific patient population likely to achieve maximal benefit, optimal dosage regimens, and the long-term adverse effects of extended duration of therapy are unknown.
Second-Generation Thiazolidinediones and Hepatotoxicity
Authors: Marcy Todd R , Britton Mark L , Blevins Steve M
Published: July 2004

OBJECTIVE:

To report a case of hepatotoxicity probably caused by pioglitazone, summarize case reports of hepatotoxicity induced by rosiglitazone or pioglitazone, and make recommendations regarding routine liver enzyme measurement in patients taking these agents.

CASE SUMMARY:

A 39-year-old black woman with type 2 diabetes mellitus, hypertension, and congestive heart failure presented to a pharmacist-staffed diabetes comanagement service. She reported fatigue, dark brown urine, nausea, itching, and loss of appetite. Pioglitazone was promptly discontinued because her symptoms were consistent with those of hepatic dysfunction and pioglitazone was identified as a potential cause. The patient was referred to her physician. Liver enzyme levels were checked 13 days after initial presentation and found to be abnormal: alanine aminotransferase 490 U/L, aspartate aminotransferase 360 U/L, alkaline phosphatase 851 U/L, total bilirubin 3.1 mg/dL, direct bilirubin 2.0 mg/dL, and indirect bilirubin 1.1 mg/dL. Within 21/2 months of discontinuing pioglitazone, the patient's symptoms resolved and liver enzyme levels returned to normal.

DISCUSSION:

Troglitazone, a thiazolidinedione (TZD), was removed from the market because of hepatotoxicity. Reported cases involving the newer TZDs, rosiglitazone and pioglitazone, have been few in number and less severe in consequence. Six cases of rosiglitazone-induced hepatotoxicity and 5 of pioglitazone-induced hepatotoxicity have been reported. Most patients improved symptomatically 2–4 weeks following discontinuation of the offending TZD, with normalization of liver enzyme levels in 2 weeks to 6 months following TZD discontinuation.

CONCLUSIONS:

Although the timeline and extent of liver enzyme elevation in this case are unclear, the Naranjo probability scale suggests that a causal relationship between pioglitazone and liver disease is probable. Patients with previous TZD-induced hepatotoxicity should not be rechallenged. Cases of hepatotoxicity with second generation TZDs, although clearly linked, have been few in number and less severe in consequence when compared to troglitazone. We agree with current package labeling that requires baseline and then periodic measurement of liver enzymes in patients taking pioglitazone or rosiglitazone.
Severe Acquired Hemophilia with Factor VIII Inhibition Associated with Acetaminophen and Chlorpheniramine
Authors: Famularo Giuseppe , De Maria Silvia , Minisola Giovanni , Nicotra Giulio Cesare
Published: July 2004

OBJECTIVE:

To report a case of acquired hemophilia with a high-titer factor VIII inhibitor associated with the use of acetaminophen and chlorpheniramine in combination.

CASE SUMMARY:

An 83-year-old woman presented with a severe bleeding disorder 2 weeks after she was prescribed acetaminophen and chlorpheniramine for treatment of a flu-like illness. Laboratory studies showed severe anemia with greatly reduced factor VIII activity and the presence of a high-titer factor VIII inhibitor at 228 Bethesda units. Treatment with high-dose corticosteroids, transfusion of several units of red blood cells, and repeated infusions of factor VIII bypassing activity was successful. Complete clinical and laboratory remission was achieved after 4 weeks of treatment. Use of the Naranjo probability scale suggested a possible association between this adverse event and treatment with acetaminophen and chlorpheniramine.

DISCUSSION:

Acquired hemophilia due to factor VIII inhibitor(s) has been associated with the use of drugs such as thioxanthenes, interferon, and fludarabine. As of this writing, to the best of our knowledge, no other case has been reported among patients receiving acetaminophen or chlorpheniramine.

CONCLUSIONS:

We suggest that acquired hemophilia due to factor VIII inhibitor(s) should be considered in the appropriate setting when patients present with unexplained and even minor bleeding while on treatment with acetaminophen or chlorpheniramine alone or combined.
Molecular Heterogeneity Has a Major Impact on the Measurement of Circulating N-Terminal Fragments of A- and B-Type Natriuretic Peptides
Authors: Ala-Kopsala Minna , Magga Jarkko , Peuhkurinen Keijo , Leipälä Jaana , Ruskoaho Heikki , Leppäluoto Juhani , Vuolteenaho Olli
Published: July 2004

Background: The N-terminal fragments of A- and B-type natriuretic peptides (NT-proANP and NT-proBNP) are powerful markers of cardiac function. The current assays require refinement with regard to standardization with native calibrators and the ability to detect the actual circulating forms.

Methods: The following peptides were prepared with recombinant methods: NT-proANP, NT-proBNP, proBNP1–108, and Tyr0-proBNP77–108. Fifteen peptides of 13–22 amino acids, spanning the sequences of NT-proANP and NT-proBNP, were prepared by solid-phase peptide synthesis. Two immunoassays for NT-proANP and four for NT-proBNP were set up, each with a different epitope specificity. The assays were applied for the measurement of NT-proANP and NT-proBNP in healthy individuals and in patients with acute myocardial infarction. The circulating molecular forms were analyzed by gel-filtration and reversed-phase HPLC.

Results: According to the HPLC analyses, circulating NT-proANP consists mainly of the full-length peptide, with some degradation at both ends. In contrast, circulating NT-proBNP is very heterogeneous. Most immunoreactive NT-proBNP is significantly smaller in size than NT-proBNP1–76, with truncation at both termini. The smallest fragments can be detected by assays directed at the central part of NT-proBNP only; assays directed at the ends gave 30–40% lower values. Despite the difference, the various assays correlated reasonably well with each other (r2 = 0.77–0.85). In patients with acute myocardial infarction, NT-proANP and NT-proBNP concentrations were 1.8–2.3 and 4.2–4.5 times higher than in healthy individuals. The development of heart failure further increased the concentrations.

Conclusions: Molecular heterogeneity of the circulating forms causes a serious risk of preanalytical errors in assays for NT-proBNP and, to a lesser extent, NT-proANP. The development of a sandwich assay for NT-proBNP would be especially challenging. The most robust and reliable assays use antibodies directed at the central portions of NT-proANP or NT-proBNP.
Differences in Hippocampal Neuronal Population Responses to Modifications of an Environmental Context: Evidence for Distinct, Yet Complementary, Functions of CA3 and CA1 Ensembles
Authors: Vazdarjanova Almira , Guzowski John F.
Published: July 2004

Understanding how the hippocampus processes information critical for establishing spatial and declarative memories will benefit greatly from determining not only what kind of information the hippocampus registers, but also how this information is processed across the different hippocampal subfields. We addressed this question using a novel immediate-early gene-based brain-imaging method (Arc/H1acatFISH) that allows comparisons of neuronal ensembles activated by two experiences separated by ∼30 min. Rats exposed to the same environment twice activated CA3 and CA1 ensembles with a similarly high degree of overlap. Changing the identity or configuration of local cues, or changing distal cues, activated CA3 and CA1 ensembles with reduced overlap. Yet, the overlap was greater in CA3 than in CA1. In contrast, rats exposed to two completely different environments activated CA3 and CA1 ensembles with low overlap, and this overlap was even lower in CA3 compared with CA1. Thus, CA3 has a discontinuous, whereas CA1 has a graded, population response to alterations of an environment. Additionally, as indicated by the percentage of active neurons, the context representation was more sparse in CA3 (∼18%) than in CA1 (∼35%). Finally, CA3 and CA1 activity levels were not correlated within a session, arguing against a simple coactivation of these regions. Instead, the within-rat ratio of CA3/CA1 cell activity was correlated across sessions, suggesting that the balance of CA3/CA1 activity is individual specific. Taken together, these findings suggest that CA3 and CA1 neuronal ensembles perform distinct, yet complementary, functions in the processing of spatial and contextual information.
The Ventral Striatum in Off-Line Processing: Ensemble Reactivation during Sleep and Modulation by Hippocampal Ripples
Authors: Pennartz C. M. A. , Lee E. , Verheul J. , Lipa P. , Barnes C. A. , McNaughton B. L.
Published: July 2004

Previously it has been shown that the hippocampus and neocortex can spontaneously reactivate ensemble activity patterns during post-behavioral sleep and rest periods. Here we examined whether such reactivation also occurs in a subcortical structure, the ventral striatum, which receives a direct input from the hippocampal formation and has been implicated in guidance of consummatory and conditioned behaviors. During a reward-searching task on a T-maze, flanked by sleep and rest periods, parallel recordings were made from ventral striatal ensembles while EEG signals were derived from the hippocampus. Statistical measures indicated a significant amount of reactivation in the ventral striatum. In line with hippocampal data, reactivation was especially prominent during post-behavioral slow-wave sleep, but unlike the hippocampus, no decay in pattern recurrence was visible in the ventral striatum across the first 40 min of post-behavioral rest. We next studied the relationship between ensemble firing patterns in ventral striatum and hippocampal ripples-sharp waves, which have been implicated in pattern replay. Firing rates were significantly modulated in close temporal association with hippocampal ripples in 25% of the units, showing a marked transient enhancement in the average response profile. Strikingly, ripple-modulated neurons in ventral striatum showed a clear reactivation, whereas nonmodulated cells did not. These data suggest, first, the occurrence of pattern replay in a subcortical structure implied in the processing and prediction of reward and, second, a functional linkage between ventral striatal reactivation and a specific type of high-frequency population activity associated with hippocampal replay.
Effects of PKA-Mediated Phosphorylation of Snapin on Synaptic Transmission in Cultured Hippocampal Neurons
Authors: Thakur Pratima , Stevens David R. , Sheng Zu-Hang , Rettig Jens
Published: July 2004

Use-dependent activation of protein kinase A (PKA) modulates transmitter release, contributing to synaptic plasticity. Snapin, a PKA substrate in neurons, associates with the solubleN-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, and its phosphorylation leads to increased binding of synaptotagmin to the SNARE complex. We investigated the role of PKA-dependent phosphorylation of Snapin in hippocampal neurons. Overexpression of Snapin S50D, a mutant mimicking the phosphorylated state, resulted in a decreased number of readily releasable vesicles. In addition, both the release probability of individual vesicles and the depression rate during high-frequency stimulation were increased. Overexpression of Snapin S50A, a mutant that cannot be phosphorylated, did not alter the size of the pool or the probability of release. Furthermore, dialysis of Sp-cAMPS, a nonhydrolyzable analog of cAMP that will promote phosphorylation by PKA, also led to increased synaptic depression in cells overexpressing wild-type Snapin. These results establish Snapin as an important target of PKA in CNS synapses and indicate a role for Snapin in the plasticity of transmitter release.
Role of External Pallidal Segment in Primate Parkinsonism: Comparison of the Effects of 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Induced Parkinsonism and Lesions of the External Pallidal Segment
Authors: Soares Jesus , Kliem Michele A. , Betarbet Ranjita , Greenamyre J. Timothy , Yamamoto Bryan , Wichmann Thomas
Published: July 2004

These experiments re-examined the notion that reduced activity in the external pallidal segment (GPe) results in the abnormalities of neuronal discharge in the subthalamic nucleus (STN) and the internal pallidal segment (GPi) and in the development of parkinsonian motor signs. Extracellular recording in two rhesus monkeys, which had been rendered parkinsonian by treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), revealed that the average neuronal discharge rate decreased in GPe but increased in STN and GPi. After MPTP, neurons in all three nuclei tended to discharge in oscillatory bursts. In addition, GABA release in STN (measured with microdialysis) was reduced, indicative of reduced activity along the GPe-STN pathway. Finally, the concentration of glutamic acid dehydrogenase (GAD; measured with autoimmunoradiography) was increased in GPe and GPi, likely reflecting increased striatal input and increased activity of local axon collaterals, respectively. Surprisingly, GAD protein in STN remained unchanged, indicating that the usual assumption that GAD levels are determined primarily by the overall activity of GABAergic elements may be too simplistic. The results from the MPTP-treated animals were compared with results obtained in a second group of three animals with ibotenic acid lesions of GPe. GPe lesions resulted in increased discharge in STN and GPi, comparable with the changes seen after MPTP but did not induce oscillatory bursting and had no behavioral effects. The results indicate that a mere reduction of GPe activity does not produce parkinsonism. Other changes, such as altered discharge patterns in STN and GPi, may play an important role in the generation of parkinsonism.
Neural Activity Protects Hypothalamic Magnocellular Neurons against Axotomy-Induced Programmed Cell Death
Authors: Shahar Tal , House Shirley B. , Gainer Harold
Published: July 2004

Axotomy typically leads to retrograde neuronal degeneration in the CNS. Studies in the hypothalamo-neurohypophysial system (HNS) have suggested that neural activity is supportive of magnocellular neuronal (MCN) survival after axotomy. In this study, we directly test this hypothesis by inhibiting neural activity in the HNS, bothin vivoandin vitro, by the use of tetrodotoxin (TTX). After median eminence compression to produce axonal injury, unilateral superfusion of 3 μM TTX into the rat supraoptic nucleus (SON), delivered with the use of a miniature osmotic pump for 2 weeksin vivo, produced a decrease in the number of surviving MCNs in the TTX-treated SON, compared with the contralateral untreated side of the SON.In vitroapplication of 2.5 μM TTX for 2 weeks to the SON in organotypic culture produced a 73% decrease in the surviving MCNs, compared with untreated control cultures. Raising the extracellular KCl in the culture medium to 25 mM rescued the MCNs from the axotomy- and TTX-induced cell death. These data support the proposal that after axotomy, neural activity is neuroprotective in the HNS.
Studies on the Development and Behavior of the Dystrophic Growth Cone, the Hallmark of Regeneration Failure, in anIn VitroModel of the Glial Scar and after Spinal Cord Injury
Authors: Tom Veronica J. , Steinmetz Michael P. , Miller Jared H. , Doller Catherine M. , Silver Jerry
Published: July 2004

We have developed a novelin vitromodel of the glial scar that mimics the gradient of proteoglycan foundin vivoafter spinal cord injury. In this model, regenerated axons from adult sensory neurons that extended deeply into the gradient developed bulbous, vacuolated endings that looked remarkably similar to dystrophic endings formedin vivo. We demonstrate that despite their highly abnormal appearance and stalled forward progress, dystrophic endings are extremely dynamic bothin vitroandin vivoafter spinal cord injury. Time-lapse movies demonstrated that dystrophic endings continually send out membrane veils and endocytose large membrane vesicles at the leading edge, which were then retrogradely transported to the rear of the “growth cone.” This direction of movement is contrary to membrane dynamics that occur during normal neurite outgrowth. As further evidence of this motility, dystrophic endings endocytosed large amounts of dextran bothin vitroandin vivo. We now have anin vitromodel of the glial scar that may serve as a potent tool for developing and screening potential treatments to help promote regeneration past the lesionin vivo.
Motor Skill Learning Depends on Protein Synthesis in Motor Cortex after Training
Authors: Luft Andreas R. , Buitrago Manuel M. , Ringer Thomas , Dichgans Johannes , Schulz Jörg B.
Published: July 2004

The role of protein synthesis in memory consolidation is well established for hippocampus-dependent learning and synaptic plasticity. Whether protein synthesis is required for motor skill learning is unknown. We hypothesized that skill learning is interrupted by protein synthesis inhibition (PSI). We intended to test whether local protein synthesis in motor cortex or cerebellum is required during skill acquisition and consolidation. Anisomycin (ANI; 100 μg/μl in 1 μl of PBS) injected into motor cortex, posterior parietal cortex, or cerebellum produced 84.0 ± 1.44% (mean ± SEM), 85.9 ± 2.31%, and 87.3 ± 0.17% of PSI 60 min after administration, respectively. In motor cortex, protein synthesis was still reduced at 24 hr (72.0 ± 4.68% PSI) but normalized at 48 hr after a second injection given 24 hr after the first. To test for the effects of PSI on learning of a skilled reaching task, ANI was injected into motor cortex contralateral to the trained limb or into ipsilateral cerebellum immediately after daily training sessions 1 and 2. Two control groups received motor cortex injections of vehicle or ANI injections into contralateral parietal cortex. Control and cerebellar animals showed a sigmoid learning curve, which plateaued after day 4. PSI in motor cortex significantly reduced learning during days 1-4. Thereafter, when protein synthesis normalized, learning was reinitiated. ANI injections into motor cortex did not induce a motor deficit, because animals injected during the performance plateau did not deteriorate. This demonstrates that motor skill learning depends onde novosynthesis of proteins in motor cortex after training.
Overexpression of Glial Cell Line-Derived Neurotrophic Factor Using a Lentiviral Vector Induces Time- and Dose-Dependent Downregulation of Tyrosine Hydroxylase in the Intact Nigrostriatal Dopamine System
Authors: Georgievska Biljana , Kirik Deniz , Björklund Anders
Published: July 2004

The effects of continuous glial cell line-derived neurotrophic factor (GDNF) overexpression in the intact nigrostriatal dopamine (DA) system was studied using recombinant lentiviral (rLV) vector delivery of GDNF to the striatum or substantia nigra (SN) in the rat. Intrastriatal delivery of rLV-GDNF resulted in significant overexpression of GDNF in the striatum (2-4 ng/mg tissue) and anterograde transport of GDNF protein to the SN. Striatal rLV-GDNF delivery initially induced an increase in DA turnover (1-6 weeks), accompanied by significant contralateral turning in response to amphetamine, suggesting an enhancement of the DA system on the injected side. Starting 6 weeks after continuous GDNF delivery, we observed a selective downregulation of tyrosine hydroxylase (TH) protein (≈70%) that was maintained until the end of the experiment (24 weeks). A similar effect was observed when rLV-GDNF was injected into the SN. The magnitude of TH downregulation was related to the level of GDNF expression and was most pronounced in animals in which the striatal GDNF level exceeded 0.7 ng/mg tissue. The decreased TH protein levels were associated with similar reductions in thein vitroTH enzyme activity (≈70%); however,in vivol-3,4-dihydroxyphenylalanine production rate and DA tissue levels were maintained at normal levels. The results indicate that downregulation of TH protein reflects a compensatory effect in response to continuous GDNF stimulation of the DA neurons mediated by a combination of overactivity at the DA synapse and a direct GDNF-induced action on TH gene expression. This compensatory mechanism is proposed to maintain long-term DA neuron function within the normal range.
cGMP-Dependent Kinase Regulates Response Sensitivity of the Mouse On Bipolar Cell
Authors: Snellman Josefin , Nawy Scott
Published: July 2004

The visual system can adjust its sensitivity over a wide range of light intensities. Photoreceptors account for some of this adjustment, but there is evidence that postreceptoral processes also exist. To investigate the latter, we pharmacologically mimicked the effects of light stimulation on mouse On bipolar cells, thus avoiding confounding effects of receptoral mechanisms. Here, we report that cGMP selectively enhances responses to dim, but not bright, stimuli through a purely postsynaptic mechanism. This action of cGMP was completely blocked by inhibitors of cGMP-dependent kinase. We propose that cGMP-dependent kinase decreases coupling of the On bipolar cell glutamate receptor to the downstream cascade, thus amplifying small decreases in photoreceptor transmitter levels that would otherwise go undetected by the visual system.
A Complete Genetic Analysis of Neuronal Rab3 Function
Authors: Schlüter Oliver M. , Schmitz Frank , Jahn Reinhard , Rosenmund Christian , Südhof Thomas C.
Published: July 2004

Rab3A, Rab3B, Rab3C, and Rab3D are closely related GTP-binding proteins of synaptic vesicles that may function in neurotransmitter release. We have produced knock-out (KO) mice for Rab3B and Rab3C and crossed them with previously generated Rab3A and 3D knock-out mice to generate double, triple, and quadruple Rab3 knock-out mice. We have found that all single and double Rab3 knock-out mice are viable and fertile. Most triple Rab3 knock-out mice perish whenever Rab3A is one of the three deleted proteins, whereas all triple knock-out mice that express Rab3A are viable and fertile. Finally, all quadruple knock-out mice die shortly after birth. Quadruple Rab3 KO mice initially develop normally and are born alive but succumb to respiratory failure. Rab3-deficient mice display no apparent changes in synapse structure or brain composition except for a loss of rabphilin, a Rab3-binding protein. Analysis of cultured hippocampal neurons from quadruple knock-out mice uncovered no significant change in spontaneous or sucrose-evoked release but an ∼30% decrease in evoked responses. This decrease was caused by a decline in the synaptic and the vesicular release probabilities, suggesting that Rab3 proteins are essential for the normal regulation of Ca2+-triggered synaptic vesicle exocytosis but not for synaptic vesicle exocytosis as such. Our data show that Rab3 is required for survival in mice and that the four Rab3 proteins are functionally redundant in this role. Furthermore, our data demonstrate that Rab3 is not in itself essential for synaptic membrane traffic but functions to modulate the basic release machinery.
Pain Encoding in the Human Forebrain: Binary and Analog Exteroceptive Channels
Authors: Lenz Fred A. , Ohara Shinji , Gracely Rick H. , Dougherty Patrick M. , Patel Salil H.
Published: July 2004

The neuronal system signaling pain has often been characterized as a labeled line consisting of neurons in the pain-signaling pathway to the brain [spinothalamic tract (STT)] that respond only to painful stimuli. It has been proposed recently that the STT contains a series of analog labeled lines, each signaling a different aspect of the internal state of the body (interoception) (e.g., visceral-cold-itch sensations). In this view, pain is the unpleasant emotion produced by disequilibrium of the internal state. We now show that stimulation of an STT receiving zone in awake humans (66 patients) produces two different responses. The first is a binary response signaling the presence of painful stimuli. The second is an analog response in which nonpainful and painful sensations are graded with intensity of the stimulus. Compared with the second pathway, the first was characterized by higher pain ratings and stimulus-evoked sensations covering more of the body surface (projected fields). Both painful responses to stimulation were described in terms usually applied to external stimuli (exteroception) rather than to internal or emotional phenomena, which were infrequently evoked by stimulation of either pathway. These results are consistent with those of functional imaging studies that have identified brain regions activated in a binary manner by the application of a specific, painful stimulus while increases in stimulus intensity do not produce increased activation. Such binary pain functions could be involved in pain-related alarm-alerting functions, which are independent of stimulus amplitude.
Mood Stabilizer Valproate Promotes ERK Pathway-Dependent Cortical Neuronal Growth and Neurogenesis
Authors: Hao Yanlei , Creson Thomas , Zhang Lei , Li Pipeng , Du Fu , Yuan Peixiong , Gould Todd D. , Manji Husseini K. , Chen Guang
Published: July 2004

Manic-depressive illness has been conceptualized as a neurochemical illness. However, brain imaging and postmortem studies reveal gray-matter reductions, as well as neuronal and glial atrophy and loss in discrete brain regions of manic-depressive patients. The roles of such cerebral morphological deficits in the neuropathophysiology and therapeutic mechanisms of manic-depressive illness are unknown. Valproate (2-propylpentanoate) is a commonly used mood stabilizer. The ERK (extracellular signal-regulated kinase) pathway is used by neurotrophic factors to regulate neurogenesis, neurite outgrowth, and neuronal survival. We found that chronic treatment of rats with valproate increased levels of activated phospho-ERK44/42 in neurons of the anterior cingulate, a region in which we found valproate-induced increases in expression of an ERK pathway-regulated gene,bcl-2. Valproate time and concentration dependently increased activated phospho-ERK44/42 and phospho-RSK1 (ribosomal S6 kinase 1) levels in cultured cortical cells. These increases were attenuated by Raf and MEK (mitogen-activated protein kinase/ERK kinase) inhibitors. Although valproate affects the functions of GSK-3 (glycogen synthase kinase-3) and histone deacetylase (HDAC), its effects on the ERK pathway were not fully mimicked by selective inhibitors of GSK-3 or HDAC. Similar to neurotrophic factors, valproate enhanced ERK pathway-dependent cortical neuronal growth. Valproate also promoted neural stem cell proliferation-maturation (neurogenesis), demonstrated by bromodeoxyuridine (BrdU) incorporation and double staining of BrdU with nestin, Tuj1, or the neuronal nuclei marker NeuN (neuronal-specific nuclear protein). Chronic treatment with valproate enhanced neurogenesis in the dentate gyrus of the hippocampus. Together, these data demonstrate that valproate activates the ERK pathway and induces ERK pathway-mediated neurotrophic actions. This cascade of events provides a potential mechanism whereby mood stabilizers alleviate cerebral morphometric deficits associated with manic-depressive illness.
Amplifiers, Optical
Authors: Mukai Takaaki
Published: July 2004

An overview of optical amplifiers, which are used for direct amplification of optical signals, is presented. The article includes the physics and device performance of practical optical amplifiers, such as semiconductor optical amplifiers, rare‐earth ion‐doped fiber amplifiers, fiber Raman amplifiers and fiber Brillouin amplifiers. System applications of optical amplifiers are also reviewed.