Thymic selection of CD8+ single positive cells with a class II major histocompatibility complex-restricted receptor

We describe mice that express a transgenic T cell receptor alpha/beta (TCR-alpha/beta) specific for peptide 111-119 from influenza hemagglutinin presented by I-Ed class II major histocompatibility complex (MHC) molecules. The transgenic TCR is expressed on CD4+8- as well as CD4-8+ mature T cells even in mice that are deficient in rearrangement or do not express endogenous TCR-alpha genes. The CD4-8+ T cells require I-Ed class II MHC molecules for positive selection and can be activated to proliferate and to kill by I-Ed molecules presenting the relevant peptide. Full maturation of these cells, however, also requires the presence of class I MHC molecules. The results are compatible with the notion that T cell maturation requires multiple receptor-ligand interactions and establish an exception to the rule that class II-restricted TCRs are exclusively expressed by mature CD4+8- cells.

Striated flagellar roots: isolation and partial characterization of a calcium-modulated contractile organelle

We report the isolation of striated flagellar roots from the Prasinophycean green alga Tetraselmis striata using sedimentation in gradients of sucrose and flotation on gradients of colloidal silica. PAGE in the presence of 0.1% SDS demonstrates that striated flagellar roots are composed of a number of polypeptides, the most predominant one being a protein of 20,000 Mr. The 20,000 Mr protein band represents approximately 63% of the Coomassie Brilliant Blue staining of gels of isolated flagellar roots. Two-dimensional gel electrophoresis (isoelectric focusing and SDS PAGE) resolves the major 20,000 Mr flagellar root protein into two components of nearly identical Mr, but of differing isoelectric points (i.e., pl's of 4.9 and 4.8), which we have designated 20,000-Mr-alpha and 20,000-Mr-beta, respectively. Densitometric scans of two-dimensional gels of cell extracts indicate that the 20,000-Mr-alpha and -beta polypeptides vary, in their stoichiometry, between 2:1 and 1:1. This variability appears to be related to the state of contraction or extension of the striated flagellar roots at the time of cell lysis. Incubation of cells with 32PO4 followed by analysis of cell extracts by two-dimensional gel electrophoresis and autoradiography reveals that the more acidic 20,000-Mr-beta component is phosphorylated and the 20,000-Mr-alpha component contains no detectable label. These results suggest that the 20,000-Mr-alpha component is converted to the more acidic 20,000-Mr-beta form by phosphorylation. Both the 20,000-Mr-alpha and -beta flagellar root components exhibit a calcium-induced reduction in relative electrophoretic mobilities in two-dimensional alkaline urea gels. Antiserum raised in rabbits against the 20,000-Mr protein binds to both the 20,000-Mr-alpha and 20,000-Mr-beta forms of the flagellar root protein when analyzed by electrophoretic immunoblot techniques. Indirect immunofluorescence on vegetative or interphase cells demonstrate that the antibodies bind to two cyclindrical organelles located in the anterior region of the cell. Immunocytochemical investigations at ultrastructural resolution using this antiserum and a colloidal gold-conjugated antirabbit-IgG reveals immunospecific labeling of striated flagellar roots and their extensions. We conclude that striated flagellar roots are simple ion-sensitive contractile organelles composed predominantly of a 20,000 Mr calcium-binding phosphoprotein, and that this protein is largely responsible for the motile behavior of these organelles.

High-throughput tissue microarray analysis used to evaluate biology and prognostic significance of the E-cadherin pathway in non-small-cell lung cancer

PURPOSE

E-cadherin (E-cad) and its associated intracellular molecules, catenins, are critical for intercellular epithelial adhesion and are often expressed in non-small-cell lung carcinomas (NSCLCs). We constructed tissue microarrays (TMAs) to investigate the expression of cadherins and catenins and their prognostic significance in NSCLC.

PATIENTS AND METHODS

Tumor tissue samples from 193 patients with stages I to III NSCLC were obtained from the University of Colorado Cancer Center and Johns Hopkins Medical Institutions. Viable tumor was sampled in triplicate for the TMAs, and slides were stained by immunohistochemistry with antibodies against E-cad, N-cadherin, alpha (alpha)-, beta (beta)-, and gamma (gamma)-catenin, p120, p27, and adenomatous polyposis coli (APC) gene product. Clinical data were collected by the tumor registries. Patients were followed for a median period of 51 months (range, 18 to 100 months).

RESULTS

Absent or severely reduced membranous expression for E-cad, alpha-, beta-, and gamma-catenin, and p120 were observed in 10%, 17%, 8%, 31%, and 61% of the cases, respectively. Tumor cell dedifferentiation correlated with reduced expression for E-cad, beta-catenin, gamma-catenin, and p120 in squamous cell carcinomas but not in adenocarcinomas. There was an inverse correlation between nodal metastasis and expression of E-cad and gamma-catenin. Besides the traditional clinical prognostic variables, E-cad and alpha-, beta-, and gamma-catenin expression were of positive prognostic value in univariate survival analyses. In multivariate analysis, E-cad expression was the only independent prognostic factor for survival in addition to age, node status, tumor status, and pathologic surgical margins.

CONCLUSION

Reduced expression of E-cad and catenins is associated with tumor cell dedifferentiation, local invasion, regional metastasis, and reduced survival in NSCLC. E-cad is an independent prognostic factor for NSCLC survival.

Interactions between apple cell walls and native apple polyphenols: quantification and some consequences

Cell walls were prepared from apple parenchyma by a phenol:buffer procedure. Polyphenols were extracted from freeze-dried apple parenchyma by methanol and water:acetone, and purified by preparative HPLC. Interactions were quantified by bringing into contact suspended cell walls and polyphenol solutions. Hydroxycinnamic acids and (-)-epicatechin did not bind to cell walls. Binding of procyanidins was fast and reached up to 0.6 g per g cell walls. The amounts of procyanidins bound increased with the initial concentration and with DPn. Procyanidins could be partially desorbed by buffer, more being desorbed in the presence of dissolved cell wall polysaccharides. They were totally desorbed using 8 M urea or acetone:water. Higher polymers were bound selectively from procyanidin mixtures, and very high average DPn were obtained in extensively washed complexes. Binding of procyanidins inhibited enzymic degradation of the cell walls.

A new class of symmetric bisbenzimidazole-based DNA minor groove-binding agents showing antitumor activity

The synthesis and evaluation of the novel head-to-head bisbenzimidazole compound 2,2-bis[4'-(3' '-dimethylamino-1' '-propyloxy)phenyl]-5,5-bi-1H-benzimidazole is described. An X-ray crystallographic study of a complex with the DNA dodecanucleotide sequence d(CGCGAATTCGCG) shows the compound bound in the A/T minor groove region of a B-DNA duplex and that the head-to-head bisbenzimidazole motif hydrogen-bonds to the edges of all four consecutive A:T base pairs. The compound showed potent growth inhibition with a mean IC(50) across an ovarian carcinoma cell line panel of 0.31 microM, with no significant cross-resistance in two acquired cisplatin-resistant cell lines and a low level of cross-resistance in the P-glycoprotein overexpressing acquired doxorubicin-resistant cell line. Studies with the hollow fiber assay and in vivo tumor xenografts showed some evidence of antitumor activity.

Sec-independent protein translocation by the maize Hcf106 protein

The bacterial Sec and signal recognition particle (ffh-dependent) protein translocation mechanisms are conserved between prokaryotes and higher plant chloroplasts. A third translocation mechanism in chloroplasts [the proton concentration difference (DeltapH) pathway] was previously thought to be unique. The hcf106 mutation of maize disrupts the localization of proteins transported through this DeltapH pathway in isolated chloroplasts. The Hcf106 gene encodes a receptor-like thylakoid membrane protein, which shows homology to open reading frames from all completely sequenced bacterial genomes, which suggests that the DeltapH pathway has been conserved since the endosymbiotic origin of chloroplasts. Thus, the third protein translocation pathway, of which HCF106 is a component, is found in both bacteria and plants.

Evaluation of HER-2/neu gene amplification and protein expression in non-small cell lung carcinomas

HER-2/neu gene amplification and cell surface overexpression are important factors in breast cancer for prognosis and prediction of sensitivity to anti-HER-2/neu monoclonal antibody therapy. In lung cancer, the clinical significance of HER-2/neu expression is currently under evaluation. We investigated 238 non-small lung carcinomas for HER-2/neu protein overexpression by immunohistochemistry using the HercepTest. We found 2+ or 3+ overexpression in 39 patients (16%), including 35% in adenocarcinomas and 20% in large cell carcinomas, but only 1% of squamous cell carcinomas. Marked (3+) overexpression was uncommon (4%). The association between protein expression and gene copy number per cell, as determined by fluorescence in situ hybridisation assay, was investigated in 51 of these NSCLC tumours. Twenty-seven tumours (53%) were negative by both tests. Marked (3+) protein expression and gene amplification were present in only 4% of samples. In 11 tumours (21%), gene gain was accompanied by chromosomal aneusomy and did not result in high protein levels while in 7 (14%) the score 2+ was associated with maximum number of signals per cell <9. The prognostic implication of HER-2/neu protein expression was studied in 187 surgically resected tumours. No statistical difference in survival was observed comparing patients with positive (2+/3+) and negative tumours (0/1+), although 3+ patients showed a tendency to shorter survival. The therapeutic implications of protein expression and gene amplification in lung cancer need to be examined in prospective clinical trials.

Gene expression of GLUT4 in skeletal muscle from insulin-resistant patients with obesity, IGT, GDM, and NIDDM

In obesity, impaired glucose tolerance (IGT), non-insulin-dependent diabetes mellitus (NIDDM), and gestational diabetes mellitus (GDM), defects in glucose transport system activity, contribute to insulin resistance in target tissues. In adipocytes from obese and NIDDM patients, we found that pretranslational suppression of the insulin-responsive GLUT4 glucose transporter isoform is a major cause of cellular insulin resistance; however, whether this process is operative in skeletal muscle is not clear. To address this issue, we performed percutaneous biopsies of the vastus lateralis in lean and obese control subjects and in obese patients with IGT and NIDDM and open biopsies of the rectus abdominis at cesarian section in lean and obese gravidas and gravidas with GDM. GLUT4 was measured in total postnuclear membrane fractions from both muscles by immunoblot analyses. The maximally insulin-stimulated rate of in vivo glucose disposal, assessed with euglycemic glucose clamps, decreased 26% in obesity and 74% in NIDDM, reflecting diminished glucose uptake by muscle. However, in vastus lateralis, relative amounts of GLUT4 per milligram membrane protein were similar (NS) among lean (1.0 +/- 0.2) and obese (1.5 +/- 0.3) subjects and patients with IGT (1.4 +/- 0.2) and NIDDM (1.2 +/- 0.2). GLUT4 content was also unchanged when levels were normalized per wet weight, per total protein, and per DNA as an index of cell number. Levels of GLUT4 mRNA were similarly not affected by obesity, IGT, or NIDDM whether normalized per RNA or for the amount of an unrelated constitutive mRNA species. Because muscle fibers (types I and II) exhibit different capacities for insulin-mediated glucose uptake, we tested whether a change in fiber composition could cause insulin resistance without altering overall levels of GLUT4. However, we found that quantities of fiber-specific isoenzymes (phopholamban and types I and II Ca(2+)-ATPase) were similar in all subject groups. In rectus abdominis, GLUT4 content was similar in the lean, obese, and GDM gravidas whether normalized per milligram membrane protein (relative levels were 1.0 +/- 0.2, 1.3 +/- 0.1, and 1.0 +/- 0.2, respectively) or per wet weight, total protein, and DNA. We conclude that in human disease states characterized by insulin resistance, i.e., obesity, IGT, NIDDM, and GDM, GLUT4 gene expression is normal in vastus lateralis or rectus abdominis. To the extent that these muscles are representative of total muscle mass, insulin resistance in skeletal muscle may involve impaired GLUT4 function or translocation and not transporter depletion as observed in adipose tissue.

Platelet reactivity in depressed patients treated with paroxetine: preliminary findings

BACKGROUND

Alterations in platelet reactivity have been previously posited to underlie the increased vulnerability of patients with depression to ischemic heart disease (IHD). The present study sought to determine whether the increased platelet reactivity associated with major depression is reduced after antidepressant treatment.

METHODS

Patients diagnosed as having DSM-IV major depression (n = 15) (mean age, 37 +/- 7 years; range, 23-48 years) and 12 normal comparison subjects (mean age, 36 +/- 7; range, 23-48 years) were recruited. None of the controls or depressed group had evidence of IHD; 10 of 15 patients who were depressed had 1 or more traditional IHD risk factors. In vivo platelet activation, secretion, and dose-response aggregation of the controls and patients was measured after overnight bedrest under basal conditions, and after a mild exercise challenge. After 6 weeks of open-label treatment with the selective serotonin reuptake inhibitor paroxetine (20 mg/d), the patients with depression were readmitted and procedures of the first General Clinical Research Center admission repeated.

RESULTS

In comparison with the control group, the depressed group exhibited greater procoagulant activity as detected by increased platelet binding of the monoclonal antibodies anti-ligand-induced binding site and GA6, and increased plasma concentrations of platelet factor 4 under basal conditions. After paroxetine treatment, the patients with depression exhibited significant reductions in all 3 parameters.

CONCLUSIONS

Normalization of platelet activation is associated with paroxetine treatment of patients with depression. Because this study design did not allow for the determination of whether this effect of paroxetine on platelet function is caused by a direct effect of the drug or placebo or, alternatively, because of recovery from depression, studies containing a placebo and/or psychotherapy treatment arm may resolve this issue.

Zn2+ and H+ are coactivators of acid-sensing ion channels

Acid-sensing ion channels (ASICs) are cationic channels activated by extracellular protons. They are expressed in sensory neurons, where they are thought to be involved in pain perception associated with tissue acidosis. They are also expressed in brain. A number of brain regions, like the hippocampus, contain large amounts of chelatable vesicular Zn(2+). This paper shows that Zn(2+) potentiates the acid activation of homomeric and heteromeric ASIC2a-containing channels (i.e. ASIC2a, ASIC1a+2a, ASIC2a+3), but not of homomeric ASIC1a and ASIC3. The EC(50) for Zn(2+) potentiation is 120 and 111 microm for the ASIC2a and ASIC1a+2a current, respectively. Zn(2+) shifts the pH dependence of activation of the ASIC1a+2a current from a pH(0.5) of 5.5 to 6.0. Systematic mutagenesis of the 10 extracellular histidines of ASIC2a leads to the identification of two residues (His-162 and His-339) that are essential for the Zn(2+) potentiating effect. Mutation of another histidine residue, His-72, abolishes the pH sensitivity of ASIC2a. This residue, which is located just after the first transmembrane domain, seems to be an essential component of the extracellular pH sensor of ASIC2a.

Dynamic MR colpocystorectography assessing pelvic-floor descent

Magnetic resonance colpocystorectography (MR-CCRG) is presented in the evaluation of patients with pelvic-floor disorders. Five healthy volunteers and 44 female patients with isolated or combined visceral descent underwent dynamic MRI and dynamic fluoroscopy (DF). MR-CCRG was performed with the patient in a supine position using a True FISP sequence (1 image/1.2 s; in-plane resolution 1.02 mm) during pelvic floor contraction, relaxation, and straining maneuvers. Relevant organs, such as urethra, bladder, vagina, and rectum, were opacified by using a saline solution, Magnevist (Schering AG, Berlin, Germany), and sonography gel, respectively. The clinical evaluation and the intraoperative results (30 cases) were used as reference. MR-CCRG and DF were non-diagnostic in 3 cases each. Most patients had a combined type of visceral prolapse, the most frequent combination being a vaginal vault prolapse and a cystocele. The points of reference were sufficiently outlined by DF and MR-CCRG. In comparison with the clinical and intraoperative results, MR-CCRG proved to be especially beneficial in the diagnosis of different types of enteroceles including a uterovaginal prolapse. MR-CCRG showed an equal or higher sensitivity and specificity for all individual sites when compared with DF. Also, predominant herniation obscuring other concomitant prolapse could be verified in 8 cases. MR-CCRG is superior to DF and accurately depicts pelvic-floor descent and prolapse in women. The possibility of dynamic presentation (see enclosed CD-ROM) allows for a better understanding of the organ movements within a given topographic reference setting.

Gene expression profiles of pancreatic cancer and stromal desmoplasia

Gene expression studies were undertaken in normal pancreas and pancreatic adenocarcinomas to determine new candidate genes that can potentially be used as markers of the disease. The characteristic desmoplastic stromal reaction of pancreatic adenocarcinoma greatly hampers expression studies in this tumour type, and usually necessitates time-consuming tissue microdissection for enrichment of the tumour cell population. We show that fine needle aspiration of cancer provides a fast and efficient way of obtaining samples highly enriched in tumour cells with sufficient yields of RNA. Using Atlas cancer cDNA arrays with 588 cancer-related genes, we describe gene expression profiles of normal pancreas, bulk pancreatic tumour tissues and pancreatic tumour aspirates containing more than 95% tumour cells. Analysis of bulk tissue specimens revealed differentially expressed genes belonging predominantly to the stromal component of the tumour. This contrasted with the results obtained from tumour-cell enriched samples. Several genes already described in pancreatic cancer (caspase 8, TIMP1, CD9, IL-13) were also differentially expressed in our study. Furthermore, we found dysregulated expression of genes not previously associated with pancreatic adenocarcinoma, such as Rac 1, GLG1, NEDD5, RPL-13a, RPS9 and members of the Wnt5A gene family. In summary, we present a panel of genes newly identified in the pathogenesis of pancreatic adenocarcinoma and demonstrate that fine needle aspirates of the tumour mass are a convenient source of material for gene expression studies in tumours accompanied by desmoplastic reactions.

Quantitative HOX expression in chromosomally defined subsets of acute myelogenous leukemia

We used a degenerate RT-PCR screen and subsequent real-time quantitative RT-PCR assays to examine the expression of HOX and TALE-family genes in 34 cases of chromosomally defined AML for which outcome data were available. AMLs with favorable cytogenetic features were associated with low overall HOX gene expression whereas poor prognostic cases had high levels. Characteristically, multiple HOXA family members including HOXA3-HOXA10 were jointly overexpressed in conjunction with HOXB3, HOXB6, MEIS1 and PBX3. Higher levels of expression were also observed in the FAB subtype, AML-M1. Spearmann correlation coefficients indicated that the expression levels for many of these genes were highly inter-related. While we did not detect any significant correlations between HOX expression and complete response rates or age in this limited set of patients, there was a significant correlation between event-free survival and HOXA7 with a trend toward significance for HoxA9, HoxA4 and HoxA5. While patients with elevated HOX expression did worse, there were notable exceptions. Thus, although HOX overexpression and clinical resistance to chemotherapy often coincide, they are not inextricably linked. Our results indicate that quantitative HOX analysis has the potential to add new information to the management of patients with AML, especially where characteristic chromosomal alterations are lacking.

Ligand specificities of recombinant retinoic acid receptors RAR alpha and RAR beta

Binding of retinoic acid (RA) to specific RA receptors alpha and beta (RAR alpha and RAR beta) was studied. Receptors were obtained in two ways: (1) full-length receptors were produced by transient expression of the respective human cDNAs in COS 1 cells; and (2) the ligand-binding domains of RAR alpha and RAR beta were produced in Escherichia coli. RA binding to the wild-type and truncated forms of the receptor was identical for both RAR alpha and RAR beta, indicating that the ligand-binding domains have retained the binding characteristics of the intact receptors. Furthermore, RA bound with the same affinity to both RAR alpha and RAR beta. Only retinoid analogues with an acidic end-group were able to actively bind to both receptors. On measuring the binding of various retinoids, we have found that the properties of the ligand-binding sites of RAR alpha and RAR beta were rather similar. Two retinoid analogues were capable of binding preferentially to either RAR alpha or RAR beta, suggesting that it may be possible to synthesize specific ligands for RAR alpha and RAR beta.

Different action patterns for apple pectin methylesterase at pH 7.0 and 4.5

The mechanism of action of purified apple pectin methylesterase on pectin (degree of methoxylation: DM 75) and methoxylated homogalacturonans (DM 70 and 90) was studied at pH 7.0 (optimal pH of the enzyme) and at pH 4.5 (close to the pH of apple juice). Different interchain distributions of the free carboxyl groups were obtained at pH 7.0 and 4.5: high-performance ion exchange chromatography indicated a typical single chain mechanism at pH 7.0, but a mechanism differing from the single and multiple chain ones at pH 4.5. However, the same intrachain distribution of the newly demethoxylated galacturonic acid residues was observed for both pHs by 1H NMR. The high content of consecutive de-esterified or consecutive esterified galacturonic acid residues suggested that apple PME acted with a multiple attack mechanism on the pectic substrate. The degree of multiple attack of the enzyme was greater than or equal to 10-11.

Vaccinia-based oncolytic immunotherapy Pexastimogene Devacirepvec in patients with advanced hepatocellular carcinoma after sorafenib failure: a randomized multicenter Phase IIb trial (TRAVERSE)

Pexastimogene devacirepvec (Pexa-Vec) is a vaccinia virus-based oncolytic immunotherapy designed to preferentially replicate in and destroy tumor cells while stimulating anti-tumor immunity by expressing GM-CSF. An earlier randomized Phase IIa trial in predominantly sorafenib-naïve hepatocellular carcinoma (HCC) demonstrated an overall survival (OS) benefit. This randomized, open-label Phase IIb trial investigated whether Pexa-Vec plus Best Supportive Care (BSC) improved OS over BSC alone in HCC patients who failed sorafenib therapy (TRAVERSE).

129 patients were randomly assigned 2:1 to Pexa-Vec plus BSC vs. BSC alone. Pexa-Vec was given as a single intravenous (IV) infusion followed by up to 5 IT injections. The primary endpoint was OS. Secondary endpoints included overall response rate (RR), time to progression (TTP) and safety.

A high drop-out rate in the control arm (63%) confounded assessment of response-based endpoints. Median OS (ITT) for Pexa-Vec plus BSC vs. BSC alone was 4.2 and 4.4 months, respectively (HR, 1.19, 95% CI: 0.78–1.80; p = .428). There was no difference between the two treatment arms in RR or TTP. Pexa-Vec was generally well-tolerated. The most frequent Grade 3 included pyrexia (8%) and hypotension (8%). Induction of immune responses to vaccinia antigens and HCC associated antigens were observed.

Despite a tolerable safety profile and induction of T cell responses, Pexa-Vec did not improve OS as second-line therapy after sorafenib failure. The true potential of oncolytic viruses may lie in the treatment of patients with earlier disease stages which should be addressed in future studies.

ClinicalTrials.gov: NCT01387555

Assessment of the biological and pharmacological effects of the ανβ3 and ανβ5 integrin receptor antagonist, cilengitide (EMD 121974), in patients with advanced solid tumors

BACKGROUND

Cilengitide, an antiangiogenic agent that inhibits the binding of integrins alpha(nu)beta(3) and alpha(nu)beta(5) to the extracellular matrix, was studied at two dose levels in cancer patients to determine the optimal biological dose.

PATIENTS AND METHODS

The doses of cilengitide were 600 or 1200 mg/m(2) as a 1-h infusion twice weekly every 28 days. A novel dose escalation scheme was utilized that relied upon the biological activity rate.

RESULTS

Twenty patients received 50 courses of cilengitide with no dose-limiting toxic effects. The pharmacokinetic (PK) profile revealed a short elimination half-life of 4 h, supporting twice weekly dosing. Of the six soluble angiogenic molecules assessed, only E-selectin increased significantly from baseline. Analysis of tumor microvessel density and gene expression was not informative due to intrapatient tumor heterogeneity. Although several patients with evaluable tumor biopsy pairs did reveal posttreatment increases in tumor and endothelial cell apoptosis, these results did not reach statistical significance due to the aforementioned heterogeneity.

CONCLUSIONS

Cilengitide is a well-tolerated antiangiogenic agent. The biomarkers chosen in this study underscore the difficulty in assessing the biological activity of antiangiogenic agents in the absence of validated biological assays.

Hox-5.1 defines a homeobox-containing gene locus on mouse chromosome 2

We have isolated a murine homeobox-containing gene, Hox-5.1, by virtue of its relatedness to the Hox-1.4 gene. In situ hybridization to metaphase spreads mapped Hox-5.1 to band D of mouse chromosome 2. Sequence comparisons indicate that Hox-5.1 is the murine homolog of the human C13 homeobox-containing gene. Hox-5.1 also bears significant similarity to the Xenopus Xhox-1A homeobox-containing gene and the Drosophila deformed homeotic gene at N-terminal and homeobox regions. Hox-5.1 transcripts were detected in mouse embryos, in adult mouse testis, kidney, heart, and intestine, and in mouse embryonal carcinoma cells treated with retinoic acid. In situ hybridization to sections from whole mouse embryos revealed Hox-5.1 expression in spinal cord and prevertebrae.

T cell receptor (TCR) beta chain homodimers on the surface of immature but not mature alpha, gamma, delta chain deficient T cell lines

Transfected T cell receptor (TCR) beta chain genes are expressed as homodimers on the surface of immature (Sci/ET27F) but not on mature (58 alpha-beta-) T cell lines which lack TCR alpha, gamma and delta chains. The homodimer on Sci/ET27F cells is tightly bound to CD3 delta and CD3 epsilon while the association with CD3 gamma and CD3 zeta proteins is rather weak. Crosslinking of the TCR beta homodimers resulted in a strong and rapid calcium flux. In 58 alpha-beta- T cells the beta TCR chain could be easily visualized intracellularly but was not transported to the cell surface. The Scid cell lines considerably facilitate the molecular analysis of early differentiation events in the thymus which are likely to be regulated by the beta TCR homodimer.

Epoxyeicosatrienoic acids activate a high-conductance, Ca(2+)-dependent K + channel on pig coronary artery endothelial cells

1. Epoxyeicosatrienoic acids (EETs) have been described as endothelium-derived hyperpolarizing factors (EDHFs), based on their stimulatory effects on smooth muscle K+ channels. In order to reveal a putative autocrine effect of EETs on endothelial channels, we have studied the effects of the four EET regioisomers (5,6-EET, 8,9-EET, 11,12-EET and 14,15-EET) on the high-conductance, Ca(2+)-dependent K+ (BKCa) channel recorded in inside-out patches of primary cultured pig coronary artery endothelial cells. Currents were recorded in the presence of either 500 nm or 1 microM free Ca2+ on the cytosolic side of the membrane. 2. In 81% of experiments, EETs at < 156 nM, applied on the cytosolic side of the membrane, transiently increased BKCa channel open state probability (PO) without affecting its unitary conductance, thus providing evidence for direct action of EETs, without involvement of a cytosolic transduction pathway. 3. The four EET regioisomers appeared to be equally active, multiplying the BKCa channel PO by a mean factor of 4.3 +/- 0.6 (n = 15), and involving an increase in the number and duration of openings. 4. The EET-induced increase in BKCa channel activity was more pronounced with low initial PO. When the BKCa channel was activated by 500 nM Ca2+, application of EETs increased the initial PO value of below 0.1 by a factor of 5. When the channel was activated by 1 microM Ca2+, application of EETs increased the initial PO value by a factor of 3. 5. Our results show that EETs potentiate endothelial BKCa channel activation by Ca2+. The autocrine action of EETs on endothelial cells, which occurs in the same concentration range as their action on muscle cells, should therefore fully participate in the vasoactive effects of EETs, and thus be taken into account when considering their putative EDHF function.

Coordinate suppression of mutations caused by Robertson's mutator transposons in maize

Transposable elements from the Robertson's Mutator family are highly active insertional mutagens in maize. However, mutations caused by the insertion of responder (non-autonomous) elements frequently depend on the presence of active regulator (autonomous) elements for their phenotypic effects. The hcf106::Mu1 mutation has been previously shown to depend on Mu activity in this way. The dominant Lesion-mimic 28 mutation also requires Mu activity for its phenotypic effects. We have used double mutants to show that the loss of Mu activity results in the coordinate suppression of both mutant phenotypes. This loss can occur somatically resulting in large clones of cells that have a wild-type phenotype. Autonomous and non-autonomous Mutator elements within these clones are insensitive to digestion with methylation-sensitive enzymes, suggesting extensive methylation of CG and non-CG cytosine residues. Our data are consistent with the sectors being caused by the cycling of MuDR regulatory elements between active and inactive phases. The pattern of sectors suggests that they are clonal and that they are derived from the apical cells of the vegetative shoot meristem. We propose that these cells are more likely to undergo epigenetic loss of Mu activity because of their longer cell division cycle during shoot growth. Coordinate suppression of unlinked mutations can be used to perform mosaic analysis in maize.

Effects of instructions and reinforcement-feedback on human operant behavior maintained by fixed-interval reinforcement

In three experiments, human subjects were trained on a five-component multiple schedule with different fixed intervals of monetary reinforcement scheduled in the different components. Subjects uninstructed about the fixed-interval schedules manifested high and generally equivalent rates regardless of the particular component. By comparison, subjects given instructions about the schedules showed orderly progressions of rates and temporal patterning as a function of the interreinforcement intervals, particularly when feedback about reinforcement was delivered but also when reinforcement-feedback was withheld. Administration of the instructions-reinforcement combination to subjects who had already developed poorly differentiated behavior, however, did not make their behavior substantially better differentiated. When cost was imposed for responding, both instructed and uninstructed subjects showed low and differentiated rates regardless of their prior histories. It was concluded that instructions can have major influences on the establishment and maintenance of human operant behavior.

Effects of neuropeptide SF and related peptides on acid sensing ion channel 3 and sensory neuron excitability

Acid sensing ion channel 3 (ASIC3) is a cation channel gated by extracellular protons. It is highly expressed in sensory neurons, including small nociceptive neurons and has been proposed to participate in pain perception associated with tissue acidosis and in mechanoperception. Neuropeptide FF (NPFF) and FMRFamide have been shown to potentiate proton-gated currents from cultured sensory neurons and acid sensing ion channel (ASIC) cDNA transfected cells. In this study, we report that another mammalian peptide neuropeptide SF (NPSF), derived from the same precursor, also considerably increases the amplitude of the sustained current of heterologously expressed ASIC3 (12-fold vs. 19- and nine-fold for FMRFamide and NPFF, respectively) with an EC(50) of approximately 50 microM. Similar effects were also observed on endogenous ASIC3-like sustained current recorded from DRG neurons although of smaller amplitudes (two-, three- and seven-fold increase for NPSF, NPFF and FMRFamide, respectively), and essentially related to a slowing down of the inactivation rate. Importantly, this modulation induced changes in neuronal excitability in response to an electrical stimulus applied during extracellular acidification. ASIC3-mediated sustained depolarisation, and its regulation by neuropeptides, could thus be important in regulating polymodal neuron excitability particularly under inflammatory conditions where the expression levels of both NPFF precursor and ASIC3 are increased.

Ectopic Hoxa-1 induces rhombomere transformation in mouse hindbrain

Homeobox genes are expressed with a specific spatial and temporal order, which is essential for pattern formation during the early development of both invertebrates and vertebrates. Here we show that widespread ectopic expression of the Hoxa-1 (Hox 1.6) gene directed by a human beta-actin promoter in transgenic mice is embryolethal and produces abnormal phenotypes in a subset of domains primarily located in anterior regions. Interestingly, this abnormal development in the Hoxa-1 transgenic mice is associated with ectopic expression of the Hoxb-1 (Hox 2.9) gene in select hindbrain regions. At gestation day 9.5, two domains of strong Hoxb-1 expression are found in the anterior region of the hindbrains of Hoxa-1 transgenic embryos. One region represents the normal pattern of Hoxb-1 expression in rhombomere 4 and its associated migrating neural crest cells, while another major domain of Hoxb-1 expression consistently appears in rhombomere 2. Similar ectopic domains of beta-galactosidase activity are detected in dual transgenic embryos containing both beta-actin/Hoxa-1 transgene and a Hoxb-1/lacZ reporter construct. Expression of another lacZ reporter gene that directs beta-galactosidase activity predominantly in rhombomere 2 is suppressed in the Hoxa-1 transgenic embryos. We have also detected weaker and variable ectopic Hoxb-1 expression in rhombomeres 1, 3 and 6. No ectopic Hoxb-1 expression is detected in rhombomere 5 and the expression of Hoxa-3 and Krox-20 in this region is unchanged in the Hoxa-1 transgenic embryos. While no obvious change in the morphology of the trigeminal or facial-acoustic ganglia is evident, phenotypic changes do occur in neurons that emanate from rhombomeres 2 and 3 in the Hoxa-1 transgenic embryos. Additionally, alterations in the pattern of Hoxa-2 and Hoxb-1 expression in a subpopulation of neural crest cells migrating from the rhombomere 2 region are detected in these transgenics. Taken together, these data suggest that ectopic Hoxa-1 expression can reorganize select regions of the developing hindbrain by inducing partial transformations of several rhombomeres into a rhombomere-4-like identity.

Fetal gender differences in preterm birth: findings in a North American cohort

A higher incidence of preterm birth (PTB) and premature rupture of membranes (PROM) has been observed among women delivering male newborns compared with female newborns in different populations. Some authors have speculated that this higher incidence of PTB may be related to the relatively greater weight at lower gestational age of male newborns compared with female newborns. Others have suggested that the greater incidence of PTB and PROM is caused by an increased vulnerability to infection in women carrying males. To understand possible pathogenic factors leading to PTB further, we examined the association between PTB and infant gender in a cohort of North American women. In addition, incidences of PROM, chorioamnionitis, and postpartum endometritis were analyzed for women delivering males versus females. Overall, males were more likely than females to deliver at 33 to 36 weeks' gestation (OR = 1.21; 95% CI: 1.02-1.42). This increase in PTB among males was not accompanied by an increased number of males with low birthweight; rather, males were less likely than females to weigh between 2000 and 2499 gm (OR = 0.71; 95% CI: 0.60-0.84). The difference in PTB by gender could not be explained by an increased occurrence of PROM, chorioamnionitis, endometritis, or other infection-linked processes. Our findings suggest that shorter gestation in males in this population may be related to their relatively increased size and birthweight. Male gender-associated factors that predispose to infection-mediated preterm birth may play greater roles in populations at higher risk for reproductive tract infection during pregnancy.