Effects of preceding endoscopic mucosal resection on the efficacy and safety of radiofrequency ablation for treatment of Barrett's esophagus: results from the United States Radiofrequency Ablation Registry.

The effects of preceding endoscopic mucosal resection (EMR) on the efficacy and safety of radiofrequency ablation (RFA) for treatment of nodular Barrett's esophagus (BE) is poorly understood. Prior studies have been limited to case series from individual tertiary care centers. We report the results of a large, multicenter registry. We assessed the effects of preceding EMR on the efficacy and safety of RFA for nodular BE with advanced neoplasia (high-grade dysplasia or intramucosal carcinoma) using the US RFA Registry, a nationwide study of BE patients treated with RFA at 148 institutions. Safety outcomes included stricture, gastrointestinal bleeding, and hospitalization. Efficacy outcomes included complete eradication of intestinal metaplasia (CEIM), complete eradication of dysplasia (CED), and number of RFA treatments needed to achieve CEIM. Analyses comparing patients with EMR before RFA to patients undergoing RFA alone were performed with Student's t-test, Chi-square test, logistic regression, and Kaplan-Meier analysis. Four hundred six patients were treated with EMR before RFA for nodular BE, and 857 patients were treated with RFA only for non-nodular BE. The total complication rates were 8.4% in the EMR-before-RFA group and 7.2% in the RFA-only group (P = 0.48). Rates of stricture, bleeding, and hospitalization were not significantly different between patients treated with EMR before RFA and patients treated with RFA alone. CEIM was achieved in 84% of patients treated with EMR before RFA, and 84% of patients treated with RFA only (P = 0.96). CED was achieved in 94% and 92% of patients in EMR-before-RFA and RFA-only group, respectively (P = 0.17). Durability of eradication did not differ between the groups. EMR-before-RFA for nodular BE with advanced neoplasia is effective and safe. The preceding EMR neither diminished the efficacy nor increased complication rate of RFA treatment compared to patients with advanced neoplasia who had RFA with no preceding EMR. Preceding EMR is not associated with poorer outcomes in RFA.

Radiofrequency ablation of Barrett's esophagus: outcomes of 429 patients from a multicenter community practice registry.

BACKGROUND AND STUDY AIMS: The use of radiofrequency ablation (RFA) for complete eradication of Barrett's esophagus has shown promise in trials conducted at predominantly tertiary academic centers; however less is known regarding outcomes in the community. We evaluated the safety and efficacy of RFA for Barrett's esophagus delivered in a community practice setting. PATIENTS AND METHODS: This was a multicenter registry conducted in community-based gastroenterology practices. Patients had confirmed intestinal metaplasia with or without dysplasia on biopsy of a Barrett's esophagus. Intervention was step-wise RFA with follow-up esophageal biopsies. Endpoints were histology-based; complete response was defined as all biopsies at most recent endoscopy negative for intestinal metaplasia (CR-IM) or dysplasia (CR-D). Three cohorts were reported: 1) safety cohort, all patients; 2) efficacy cohort A, patients with at least one biopsy session after initial treatment; 3) efficacy cohort B, patients with at least one biopsy session > or = 1 year after initial treatment. RESULTS: The safety cohort included 429 patients (71 % men, median age 59 years, median Barrett's segment 3.0 cm). There were no serious adverse events (bleeding, perforation, death), and a stricture occurred after 1.1 % of cases (2.1 % of patients). In efficacy cohort A (n = 338), CR-IM and CR-D were achieved in 72 % and 89 % of patients, respectively (median follow-up 9 months). In efficacy cohort B (n = 137), CR-IM and CR-D were achieved in 77 % and 100 % of patients, respectively (median follow-up 20 months). CONCLUSIONS: In this multicenter registry conducted at four community-based practices, the observed safety and efficacy outcomes associated with RFA for Barrett's esophagus are comparable to those previously reported in multicenter trials from predominantly tertiary academic centers.

Arabidopsis thaliana and Plant Molecular Genetics.

Arabidopsis thaliana is a small flowering plant with various properties that make it an excellent organism for experiments in molecular genetics. These properties include having a small nuclear genome, a near absence of dispersed repetitive DNA, and a generation time of 4 to 5 weeks. In addition, mutations that affect hormone synthesis and response, many different enzyme activities, and numerous developmental processes have been identified and characterized.

Genetic Evidence for a Long-Range Activity That Directs Pollen Tube Guidance in Arabidopsis.

The fertilization process of plants is governed by different kinds of cell-cell interactions. In higher plants, these interactions are required both for recognition of the pollen grain by the female reproductive system and to direct the growth of the pollen tube inside the ovary. Despite many years of study, the signaling mechanisms that guide the pollen tube toward its target, the ovule, are largely unknown. Two distinct types of principles, mechanical and chemotropic, have been suggested to account for the directed growth of the pollen tube. The first of these two types of models implies that the guidance of the pollen tube depends on the architecture and chemical properties of the female reproductive tissues, whereas the latter suggests that the ovule provides a signal for the target-directed growth of the pollen tube. To examine such a role for the ovules, we analyzed the growth path of pollen tubes in mutants defective in ovule development in Arabidopsis. The results presented here provide unique in vivo evidence for an ovule-derived, long-range activity controlling pollen tube guidance. A morphological comparison of the ovule mutants used in this study indicates that within the ovule, the haploid embryo sac plays an important role in this long-range signaling process.

Ovule Development in Wild-Type Arabidopsis and Two Female-Sterile Mutants.

Ovules are complex structures that are present in all seed bearing plants and are contained within the carpels in flowering plants. Ovules are the site of megasporogenesis and megagametogenesis and, following fertilization, develop into seeds. We combined genetic methods with anatomical and morphological analyses to dissect ovule development. Here, we present a detailed description of the morphological development of Arabidopsis ovules and report on the isolation of two chemically induced mutants, bell (bel1) and short integuments (sin1), with altered ovule development. Phenotypic analyses indicated that bel1 mutants initiate a single integument-like structure that develops aberrantly, sin1 mutants initiate two integuments, but growth of the integuments is disrupted such that cell division continues without normal cell elongation. Both mutants can differentiate archesporial cells, but neither forms a normal embryo sac. Genetic analyses indicated that bel1 segregates as a single recessive mutation, and complementation tests showed that the two mutants are not allelic. The phenotypes of the mutants indicate that normal morphological development of the integuments and proper embryo sac formation are interdependent or are governed in part by common pathways. The ovule mutants that we describe in Arabidopsis represent novel genetic tools for the study of this stage of reproductive development.

Complex sexual signals for the male gametophyte.

The pollen grain and the pollen tube that grows from it are complex entities which must respond to a diverse array of signals to carry out their roles in sexual reproduction. Research is beginning to reveal the nature both of the signals and of the signal transduction machinery that converts these signals into directional, polarized growth.

Effect of ascorbic acid deficiency on the in vivo synthesis of carnitine.

The effects of ascorbate deficiency on carnitine biosynthesis was investigated in young male guinea pigs. Liver and kidney carnitine levels were not affected by the deficiency, but scorbutic animals had 50% less carnitine in heart and skeletal muscle than control animals. Labeled carnitine precursors, 6-N-tri-methyl-L-lysine and 4-N-trimethylaminobutyrate, both of which require ascorbate for their enzymatic hydroxylation, were injected into the vena cava of control, pair-fed and scorbutic animals. The distribution of isotope in compounds present in the liver and kidney after 1 h was determined. The uptake of trimethyllysine by the liver was less than 2% in 1 h, while the kidney took up approx. 20% of the 14C. Control and pair-fed animals converted trimethyllysine to kidney trimethylaminobutyrate 8--10 times as well as did scorbutic animals. Trimethylaminobutyrate hydroxylase, present in the liver but almost absent from the kidney, converted nearly all of substrate taken up by the liver to carnitine in both the scorbutic and control animals.

Characterization of the genome of Arabidopsis thaliana.

The small crucifer Arabidopsis thaliana has many useful features as an experimental organism for the study of plant molecular biology. It has a four-week life-cycle, only five chromosomes and a genome size less than half that of Drosophila. To characterize the DNA sequence organization of this plant, we have randomly selected 50 recombinant lambda clones containing inserts with an average length of 12,800 base-pairs and analyzed their content of repetitive and unique DNA by various genome blot, restriction digestion and RNA blot procedures. The following conclusions can be drawn. The DNA represented in this random sample is composed predominantly of single-copy sequences. This presumably reflects the organization of the Arabidopsis genome as a whole and supports prior conclusions reached on the basis of kinetics of DNA reassociation. The DNA that encodes the ribosomal RNAs constitutes the only major class of cloned nuclear repetitive DNA. It consists of approximately 570 tandem copies of a heterogeneous 9900-base-pair repeat unit. There is an average of approximately 660 copies of the chloroplast genome per cell. Therefore, the chloroplast genome constitutes the major component of the repetitive sequences found in A. thaliana DNA made from whole plants. The inner cytosine residue in the sequence C-C-G-G is methylated more often than the outer in the tandem ribosomal DNA units, whereas very few differences in the methylation state of these two cytosine residues are detected in unique sequences.

DNA sequences, gene regulation and modular protein evolution in the Drosophila 68C glue gene cluster.

The 68C locus of the Drosophila melanogaster polytene chromosomes contains the structural genes for three glue polypeptides (sgs-3, sgs-7 and sgs-8) synthesized in the larval salivary glands during the third larval instar. When the messenger RNAs for the glue polypeptides are being synthesized, the locus is puffed; the puff regresses in response to the steroid hormone ecdysterone. The three 68C glue mRNAs are coded in a gene cluster of less than 5000 base-pairs, and are expressed co-ordinately. In the experiments described here we show that the coordinate expression of these RNAs does not result from amplification of the puff DNA, nor is it associated with puff DNA rearrangement. We also report the nucleotide sequence of 6751 base-pairs of genomic DNA that includes the entire gene cluster, and describe coding and non-coding sequences with possible regulatory roles. In addition, we deduce the amino acid sequences of the primary translation products of the glue mRNAs, and show that the glue proteins form a diverged gene family. The members of the family all contain an amino-terminal hydrophobic block of amino acids, which is absent in the mature, secreted glue proteins, and a cysteine-rich carboxy-terminal module. sgs-3 differs from sgs-7 and sgs-8 by containing a third module between the other two, comprised largely of tandem repeats of the five amino acids Pro-Thr-Thr-Thr-Lys.

Genetic analysis of organ fusion in Arabidopsis thaliana.

Postgenital organ fusion occurs most commonly during reproductive development and is important in many angiosperms during genesis of the carpel. Although a number of mutants have been described that manifest ectopic organ fusion, little is known about the genes involved in regulating this process. In this article we describe the characterization of a collection of 29 Arabidopsis mutants showing an organ fusion phenotype. Mapping and complementation analyses revealed that the mutant alleles define nine different loci distributed throughout the Arabidopsis genome. Multiple alleles were isolated for the four complementation groups showing the strongest organ fusion phenotype while the remaining five complementation groups, all of which show only weak floral organ fusion, have a single representative allele. In addition to fusion events between aerial parts of the shoot, some mutants also show abnormal ovule morphology with adjacent ovules joined together at maturity. Many of the fusion mutants isolated have detectable differences in the rate at which chlorophyll can be extracted; however, in one case no difference could be detected between mutant and wild-type plants. In three mutant lines pollen remained unresponsive to contact with the mutant epidermis, demonstrating that organ fusion and pollen growth responses can be genetically separated from one another.

Long-term safety of tegaserod in patients with constipation-predominant irritable bowel syndrome.

BACKGROUND: Tegaserod is a 5-hydroxytryptamine-4 receptor partial agonist. Oral administration causes gastrointestinal effects resulting in increased gastrointestinal motility and attenuation of visceral sensation. AIM: : To determine the long-term safety and tolerability of tegaserod in patients suffering from irritable bowel syndrome with constipation as the predominant symptom of altered bowel habits. METHOD: A multicentre, open-label study with flexible dose titration of tegaserod in out-patients suffering from constipation-predominant irritable bowel syndrome. RESULTS: A total of 579 patients with constipation-predominant irritable bowel syndrome were treated with tegaserod. Of these, 304 (53%) completed the trial. The most common adverse events, classified as related to tegaserod for any dose, were mild and transient diarrhoea (10.1%), headache (8.3%), abdominal pain (7.4%) and flatulence (5.5%). Forty serious adverse events were reported in 25 patients (4.4% of patients) leading to discontinuation in six patients. There was one serious adverse event, acute abdominal pain, classified as possibly related to tegaserod. There were no consistent differences in adverse events between patients previously exposed to tegaserod and those treated de novo. No pattern-forming tegaserod-related abnormalities in haematological and biochemical laboratory tests, urinalysis, blood pressure, pulse rate or electrocardiograms were found. CONCLUSIONS: Tegaserod appears to be well tolerated in the treatment of patients with constipation-predominant irritable bowel syndrome. The adverse event profile, clinical laboratory evaluations, vital signs and electrocardiogram recordings revealed no evidence of any unexpected adverse events, and suggest that treatment is safe over a 12-month period.

Endoscopy, gastric ulcer, and gastric cancer. Follow-up endoscopy for all gastric ulcers?

The practice of following benign-appearing gastric ulcers until healing was critically evaluated in a retrospective manner by reviewing all gastric ulcers that were followed with serial endoscopy and all gastric cancers diagnosed at the University of Alabama at Birmingham. The stated purpose of following ulcers to healing is to detect those gastric cancers that may be masquerading as benign ulcer and were not correctly diagnosed at initial endoscopy. Over a five-year period, 148 gastric ulcers were followed with serial endoscopy and in no case was an unsuspected carcinoma found at follow-up endoscopy. In addition, of 67 gastric cancers diagnosed between 1979 and 1986, 62 were suspected of being malignant by the endoscopist at initial examination for an accuracy of 92%. The accuracy rate based solely on biopsy and/or brush cytology was 94%. When endoscopic and biopsy and/or cytology impressions were combined, only one case of gastric carcinoma was not suspected. The overall accuracy was 99%. These results suggest that if either the endoscopic impression or the biopsy and cytology is suspicious for malignancy, then follow-up endoscopy until healing should be done. On the other hand, if, at the initial examination, the ulcer appears benign and biopsy plus cytology are negative, then serial endoscopy has a low benefit relative to its cost.

Pneumatosis cystoides intestinalis and benign pneumoperitoneum in a patient with antinuclear antibody negative systemic lupus erythematosus.

A patient with antinuclear antibody (ANA) negative systemic lupus erythematosus (SLE) developed pneumatosis cystoides intestinalis and spontaneous pneumoperitoneum. The literature of pneumatosis cystoides intestinalis and spontaneous pneumoperitoneum is reviewed, the benignancy of these conditions is emphasized, and particular attention directed to their association with and implications in the collagen vascular diseases. This is the first reported case of pneumatosis cystoides intestinalis and pneumoperitoneum in a patient with ANA negative SLE.

Molecular cloning, genomic organization, expression and evolution of 12S seed storage protein genes of Arabidopsis thaliana.

We have identified a number of genes of the flowering plant Arabidopsis thaliana that are abundantly expressed during embryogenesis. In this paper we discuss four of these genes, which comprise a gene family: complete genomic nucleotide sequence of two of the genes and partial sequence of the other two shows that they are all homologous to the 12S globulin seed storage protein genes of other angiosperms. The four genes fall into three subfamilies, as defined by cross-hybridization. One subfamily contains two genes in the Landsberg erecta strain, but only a single gene in the Columbia strain of Arabidopsis. The other two of these 12S gene subfamilies contain only single genes in both strains. Thus, the seed storage protein gene family in Arabidopsis appears much simpler than that in other higher plants.These genes are expressed during the latter half of embryogenesis, a period in which abscisic acid (ABA) is thought to play a role in gene regulation, and known to play a role in seed physiology. We observed no significant difference in the expression profiles of these four genes in ABA-deficient and ABA-insensitive mutants of Arabidopsis, except that the onset of detectable expression of all of the transcripts is slightly delayed in both types of mutants.

Identification of genes required for pollen-stigma recognition in Arabidopsis thaliana.

In higher plants, cell-cell recognition reactions taking place following pollination allow the selective restriction of self-pollination and/or interspecific pollination. Many of these systems function by regulating the process of water transfer from the cells found at the stigmatic surface to the individual pollen grain. Interspecific pollination studies on the cruciferous weed Arabidopsis thaliana revealed only a broad specificity of pollen recognition such that pollen from all tested members of the crucifer family were recognized, whereas pollen from almost all other species failed to hydrate. Genetic analysis of A. thaliana has identified three genes that are essential for this recognition process. Recessive mutations in any of these genes result in male sterility due to the production of pollen grains that fail to hydrate when placed on the stigma, but that are capable of hydrating and growing a pollen tube in vitro. Results from mixed pollination experiments suggest that the mutant pollen grains specifically lack a functional pollen-stigma recognition system. All three mutations described also result in a defect in the wax layer normally found on stems and leaves, similar to previously described eceriferum (cer) mutations. Genetic complementation and mapping experiments demonstrated that the newly identified mutants are allelic to the previously identified genes cer1, cer3 and cer6. TEM analysis of the ultrastructure of the pollen coating revealed that all of the mutant pollen grains bear coatings of normal thickness and that tryphine lipid droplets are missing in cer1-147, are reduced in size in cer6-2654 and appear normal in cer3-2186.(ABSTRACT TRUNCATED AT 250 WORDS)

Dissection of sexual organ ontogenesis: a genetic analysis of ovule development in Arabidopsis thaliana.

Understanding organogenesis remains a major challenge in biology. Specification, initiation, pattern formation and cellular morphogenesis, have to be integrated to generate the final three-dimensional architecture of a multicellular organ. To tackle this problem we have chosen the ovules of the flowering plant Arabidopsis thaliana as a model system. In a first step towards a functional analysis of ovule development, we performed a large-scale genetic screen and isolated a number of sterile mutants with aberrant ovule development, We provide indirect genetic evidence for the existence of proximal-distal pattern formation in the Arabidopsis ovule primordium. The analysis of the mutants has identified genes that act at an intermediate regulatory level and control initiation of morphogenesis in response to proximal-distal patterning. A second group of genes functions at a subordinate control level and regulates general cellular processes of morphogenesis. A large group of male and female sterile mutants shows defects restricted to early or late gametogenesis. In addition, we propose that the mature ovule obtains its overall curved shape by at least three different processes that act in only one domain of the ovule.

Molecular genetics of cell interactions in Arabidopsis.

Many events in plant development are regulated by the interactions of neighboring cells. We are interested in determining what sorts of molecules act as signals and/or receptors in these interactions and how these mechanisms relate to those used in animals and fungi. We are presently working on two different types of systems to try to address this question. In one case we are starting at the molecular level and characterizing a family of receptor protein kinase genes which seem natural candidates for mediating cellular interactions. By analyzing the expression patterns of these genes as well as the phenotypes of transgenic plants bearing altered genes we hope to determine what roles these proteins play in plant development. In the second case we are starting from the organismic level and using genetics to identify genes essential to a whole range of cellular interactions which are required for proper male gametophyte development during reproduction. These interactions involve both recognition of the pollen grain to verify that it is from the correct species and also a transfer of positional information from the female to the male which first allows the pollen tube to determine the polarity of the stigmatic cell on which it has germinated and later provides 'guidance' for the elongating tube to find the ovule.

The STUD gene is required for male-specific cytokinesis after telophase II of meiosis in Arabidopsis thaliana.

During male meiosis in wild-type Arabidopsis the pollen mother cell (PMC) undergoes two meiotic nuclear divisions in the absence of cell division. Only after telophase II is a wall formed which partitions the PMC into four microspores. Each microspore undergoes two subsequent mitotic divisions to produce one vegetative cell and two sperm cells in the mature pollen grain. In this paper we describe the isolation and the phenotypic characterization of mutations in the STUD (STD) gene, which is specifically required for male-specific cytokinesis after telophase II of meiosis. Although the male meiotic nuclear divisions are normal in std mutant plants, no walls are formed resulting in a tetranucleate microspore. Despite the absence of cell division in the PMC, postmeiotic development in the coenocytic microspore proceeds relatively normally, resulting in the formation of large pollen grains which contain four vegetative nuclei and up to eight sperm cells. Interestingly, these enlarged pollen grains which contain multiple vegetative nuclei and extra sperm cells behave as single male gametophytes, producing only single pollen tubes and resulting in partial male fertility in std mutant plants. Characterization of the process of pollen development and pollen function in std mutants thus reveals two different types of developmental regulation. Each of the four nuclei found in a std microspore following meiosis is capable of independently undergoing the complete mitotic cell division (including cytokinesis) which the single nucleus of a wild-type microspore would normally undertake. The ability of the four meiotic products to independently continue through mitosis does not depend on their division into separate cells, but is controlled by some subcellular component found within the coenocytic microspore. By contrast, the mature std pollen grain functions as a unit and produces only a single pollen tube despite the presence of multiple nuclei within the vegetative cell, suggesting that this process is controlled at the cellular level independently of the extra subcellular components.

Muscarinic cholinergic receptor subtype on frog esophageal peptic cells: binding and secretion studies.

The muscarinic receptors coupled to pepsinogen secretion on isolated frog esophageal peptic cells have been characterized using functional and radioligand binding techniques. N-[3H]methylscopolamine [( 3H]NMS) binding to intact cells was complex and indicative of a high affinity, low capacity site and a high capacity uptake site. Binding to the high capacity site was inhibited by atropine with high affinity (IC50, 3 nM) and by imipramine and propranolol with IC50 values of 70 and 270 nM, respectively. After inhibition of uptake by 30 microM propranolol, [3H]NMS bound to a single population of high affinity sites (KD, 125 +/- 16 pM), which exhibited binding site maximum of 2.1 fmol/10(6) cells, equivalent to 1260 sites/cell. Binding to these sites was reversible, stereoselective and inhibited by muscarinic receptor agonists with an order of potency: oxotremorine greater than acetylcholine greater than carbachol greater than bethanechol and by antagonists with an order of potency:atropine greater than 4-diphenylacetoxy-N-methylpiperidine methobromide greater than pirenzepine greater than AF-DX 116 (11-2[2-[[diethylamino) methyl]-1-piperidinyl]acetyl]-5, 11-dihydro-6H-pyrido[2,3-b][1,4]-benzodiazepine-6-one). Pepsinogen secretion was stimulated by the agonists with an order of potency: acetylcholine greater than or equal to carbachol greater than oxotremorine greater than bethanechol. Atropine, pirenzepine and AF-DX 116 competitively inhibited carbachol-stimulated pepsinogen secretion with pA2 values of 9.58, 7.37 and 6.68, respectively, which correlated with their log (inhibition constants) for receptor binding. By contrast, agonists with significant efficacy exhibited EC50 values which were 20 to 90 times lower than their inhibition constants for binding which suggests the possibility of "spare" muscarinic receptors. Our findings indicate that functional muscarinic receptors on peptic cells exhibit similar characteristics to the high affinity sites labeled by [3H]NMS.(ABSTRACT TRUNCATED AT 250 WORDS)