Efficacy of PARP inhibition in Pde6a mutant mouse models for retinitis pigmentosa depends on the quality and composition of individual human mutations.

Retinitis pigmentosa (RP), an inherited blinding disease, is caused by a variety of different mutations that affect retinal photoreceptor function and survival. So far there is neither effective treatment nor cure. We have previously shown that poly(ADP-ribose)polymerase (PARP) acts as a common and critical denominator of cell death in photoreceptors, qualifying it as a potential target for future therapeutic intervention. A significant fraction of RP-causing mutations affect the genes for the rod photoreceptor phosphodiesterase 6A (PDE6A) subunit, but it is not known whether they all engage the same death pathway. Analysing three homozygous point mutations (Pde6a R562W, D670G, and V685M) and one compound heterozygous Pde6a (V685M/R562W) mutation in mouse models that match human RP patients, we demonstrate excessive activation of PARP, which correlated in time with the progression of photoreceptor degeneration. The causal involvement of PARP activity in the neurodegenerative process was confirmed in organotypic retinal explant cultures treated with the PARP-selective inhibitor PJ34, using different treatment time-points and durations. Remarkably, the neuroprotective efficacy of PARP inhibition correlated inversely with the strength of the genetically induced insult, with the D670G mutant showing the best treatment effects. Our results highlight PARP as a target for neuroprotective interventions in RP caused by PDE6A mutations and are a first attempt towards personalized, genotype-matched therapy development for RP. In addition, for each of the different mutant situations, our work identifies windows of opportunity for an optimal treatment regimen for further in vivo experimentation and possibly clinical studies.

DNA methylation and differential gene regulation in photoreceptor cell death.

Retinitis pigmentosa (RP) defines a group of inherited degenerative retinal diseases causing progressive loss of photoreceptors. To this day, RP is still untreatable and rational treatment development will require a thorough understanding of the underlying cell death mechanisms. Methylation of the DNA base cytosine by DNA methyltransferases (DNMTs) is an important epigenetic factor regulating gene expression, cell differentiation, cell death, and survival. Previous studies suggested an involvement of epigenetic mechanisms in RP, and in this study, increased cytosine methylation was detected in dying photoreceptors in the rd1, rd2, P23H, and S334ter rodent models for RP. Ultrastructural analysis of photoreceptor nuclear morphology in the rd1 mouse model for RP revealed a severely altered chromatin structure during retinal degeneration that coincided with an increased expression of the DNMT isozyme DNMT3a. To identify disease-specific differentially methylated DNA regions (DMRs) on a genomic level, we immunoprecipitated methylated DNA fragments and subsequently analyzed them with a targeted microarray. Genome-wide comparison of DMRs between rd1 and wild-type retina revealed hypermethylation of genes involved in cell death and survival as well as cell morphology and nervous system development. When correlating DMRs with gene expression data, we found that hypermethylation occurred alongside transcriptional repression. Consistently, motif analysis showed that binding sites of several important transcription factors for retinal physiology were hypermethylated in the mutant model, which also correlated with transcriptional silencing of their respective target genes. Finally, inhibition of DNMTs in rd1 organotypic retinal explants using decitabine resulted in a substantial reduction of photoreceptor cell death, suggesting inhibition of DNA methylation as a potential novel treatment in RP.

Novel in situ activity assays for the quantitative molecular analysis of neurodegenerative processes in the retina.

The mechanisms of neuronal cell death are still only poorly understood, which has hindered the advancement of therapies for many currently untreatable neurodegenerative diseases. This calls for the development of new methods which reveal critical molecular mechanisms of the celldeath machinery with both high sensitivity and cellular resolution. Using animal models for hereditary neurodegeneration in the retina, we have developed or adapted different biochemical assays to determine the enzymatic activities of calpain, poly-ADP-ribose-polymerase (PARP), and histone deacetylase (HDAC) directly and in situ. Additionally, the enzymatic activity of cGMP-dependent protein kinase (PKG) was assessed indirectly using in situ immunohistological techniques to detect PKG-activity-dependent products. Combining these assays with in situ cell death markers revealed close temporospatial correlations, suggesting causal connections between the PKG, HDAC, PARP and calpain activities and neuronal cell death. Using different pharmacological and genetic manipulations, causality could indeed be demonstrated. Surprisingly, the often dramatic rises in metabolic activities didnot match by corresponding increases in expression, highlighting the importance of analyses of protein activities at the cellular level. The above mentioned studies identified a number of metabolic processes previously unknownto be involved in inherited retinal degeneration. Comparing different animal retinal degeneration models uncovered striking similarities in enzymatic activities, suggesting a generality of the destructive pathways. Taken together, these findings provided a number of novel targets for neuroprotection and as such opened up new perspectives for the therapy of hereditary neurodegeneration in the retina and possibly other parts of the central nervous system.

Knockout of PARG110 confers resistance to cGMP-induced toxicity in mammalian photoreceptors.

Hereditary retinal degeneration (RD) relates to a heterogeneous group of blinding human diseases in which the light sensitive neurons of the retina, the photoreceptors, die. RD is currently untreatable and the underlying cellular mechanisms remain poorly understood. However, the activity of the enzyme poly-ADP-ribose polymerase-1 (PARP1) and excessive generation of poly-ADP-ribose (PAR) polymers in photoreceptor nuclei have been shown to be causally involved in RD. The activity of PARP1 is to a large extent governed by its functional antagonist, poly-ADP-glycohydrolase (PARG), which thus also may have a role in RD. To investigate this, we analyzed PARG expression in the retina of wild-type (wt) mice and in the rd1 mouse model for human RD, and detected increased PARG protein in a subset of degenerating rd1 photoreceptors. Knockout (KO) animals lacking the 110 kDa nuclear PARG isoform were furthermore analyzed, and their retinal morphology and function were indistinguishable from wild-type animals. Organotypic wt retinal explants can be experimentally treated to induce rd1-like photoreceptor death, but PARG110 KO retinal explants were unexpectedly highly resistant to such treatment. The resistance was associated with decreased PAR accumulation and low PARP activity, indicating that PARG110 may positively regulate PARP1, an event that therefore is absent in PARG110 KO tissue. Our study demonstrates a causal involvement of PARG110 in the process of photoreceptor degeneration. Contrasting its anticipated role as a functional antagonist, absence of PARG110 correlated with low PARP activity, suggesting that PARG110 and PARP1 act in a positive feedback loop, which is especially active under pathologic conditions. This in turn highlights both PARG110 and PARP1 as potential targets for neuroprotective treatments for RD.

How long does a photoreceptor cell take to die? Implications for the causative cell death mechanisms.

The duration of cell death may allow deducing the underlying degenerative mechanism. To find out how long a photoreceptor takes to die, we used the rd1 mouse model for retinal neurodegeneration, which is characterized by phosphodiesterase-6 (PDE6) dysfunction and photoreceptor death triggered by high cGMP levels. Based on cellular data on the progression of cGMP accumulation, cell death, and survival, we created a mathematical model to simulate the temporal development of the degeneration and the clearance of dead cells. Both cellular data and modelling suggested that at the level of the individual cell, the degenerative process was rather slow, taking around 80 h to complete. Organotypic retinal explant cultures derived from wild-type animals and exposed to the selective PDE6 inhibitor zaprinast, confirmed the surprisingly long duration of an individual photoreceptor cell's death. We briefly discuss the possibility to link different cell death stages and their temporal progression to specific enzymatic activities known to be causally connected to cell death. This in turn opens up new perspectives for the treatment of inherited retinal degeneration, both in terms of therapeutic targets and temporal windows-of-opportunity.

Retinitis pigmentosa: rapid neurodegeneration is governed by slow cell death mechanisms.

For most neurodegenerative diseases the precise duration of an individual cell's death is unknown, which is an obstacle when counteractive measures are being considered. To address this, we used the rd1 mouse model for retinal neurodegeneration, characterized by phosphodiesterase-6 (PDE6) dysfunction and photoreceptor death triggered by high cyclic guanosine-mono-phosphate (cGMP) levels. Using cellular data on cGMP accumulation, cell death, and survival, we created mathematical models to simulate the temporal development of the degeneration. We validated model predictions using organotypic retinal explant cultures derived from wild-type animals and exposed to the selective PDE6 inhibitor zaprinast. Together, photoreceptor data and modeling for the first time delineated three major cell death phases in a complex neuronal tissue: (1) initiation, taking up to 36 h, (2) execution, lasting another 40 h, and finally (3) clearance, lasting about 7 h. Surprisingly, photoreceptor neurodegeneration was noticeably slower than necrosis or apoptosis, suggesting a different mechanism of death for these neurons.

Apgar score and perinatal death after one previous caesarean delivery.

OBJECTIVE: To assess the impact of the indication for a previous caesarean section on the outcome of a subsequent delivery. DESIGN: Population-based cohort study. SETTING: Sweden. POPULATION: Women with two deliveries between 1987 and 2007 identified using the Swedish Medical Birth Registry. METHODS: The outcome of 69 133 pregnancies after one caesarean section was compared with the outcome of 487 610 pregnancies following one vaginal delivery. The indication for the first caesarean section was estimated using a new hierarchical system based on information from birth records. MAIN OUTCOME MEASURES: Perinatal death, low Apgar score (less than seven at 5 minutes). RESULTS: Infants of women with one previous caesarean section were at increased risk of low Apgar score compared with infants of women with one previous vaginal delivery (OR, 2.0; 95% CI, 1.9-2.1). The risk estimate was reduced when adjustment for maternal and fetal/infant characteristics was made (OR, 1.6; 95% CI, 1.5-1.8). The corresponding crude and adjusted odds ratios for perinatal death were 1.6 (95% CI, 1.4-1.7) and 1.1 (95% CI, 1.0-1.2), respectively. The infant outcome of the delivery after one caesarean section was mainly dependent on the indication for the first-delivery caesarean section and, when no medical indication was present, no increase in risk was detected. CONCLUSIONS: Infants of women with one previous caesarean section were at increased risk of low Apgar score and/or perinatal death compared with infants of women with one previous vaginal delivery. The results suggest that medical conditions, not the previous caesarean section per se, contributed to the increase in risk.

Excessive HDAC activation is critical for neurodegeneration in the rd1 mouse.

Inherited retinal degenerations, collectively termed retinitis pigmentosa (RP), constitute one of the leading causes of blindness in the developed world. RP is at present untreatable and the underlying neurodegenerative mechanisms are unknown, even though the genetic causes are often established. Acetylation and deacetylation of histones, carried out by histone acetyltransferases (HATs) and histone deacetylases (HDACs), respectively, affects cellular division, differentiation, death and survival. We found acetylation of histones and probably other proteins to be dramatically reduced in degenerating photoreceptors in the rd1 human homologous mouse model for RP. Using a custom developed in situ HDAC activity assay, we show that overactivation of HDAC classes I/II temporally precedes photoreceptor degeneration. Moreover, pharmacological inhibition of HDACs I/II activity in rd1 organotypic retinal explants decreased activity of poly-ADP-ribose-polymerase and strongly reduced photoreceptor cell death. These findings highlight the importance of protein acetylation for photoreceptor cell death and survival and propose certain HDAC classes as novel targets for the pharmacological intervention in RP.

The ring nerve of the box jellyfish Tripedalia cystophora.

Box jellyfish have the most elaborate sensory system and behavioural repertoire of all cnidarians. Sensory input largely comes from 24 eyes situated on four club-shaped sensory structures, the rhopalia, and behaviour includes obstacle avoidance, light shaft attractance and mating. To process the sensory input and convert it into the appropriate behaviour, the box jellyfish have a central nervous system (CNS) but this is still poorly understood. The CNS has two major components: the rhopalial nervous system and the ring nerve. The rhopalial nervous system is situated within the rhopalia in close connection with the eyes, whereas the ring nerve encircles the bell. We describe the morphology of the ring nerve of the box jellyfish Tripedalia cystophora as ascertained by normal histological techniques, immunohistochemistry and transmission electron microscopy. By light microscopy, we have estimated the number of cells in the ring nerve by counting their nuclei. In cross sections at the ultrastructural level, the ring nerve appears to have three types of neurites: (1) small "normal"-looking neurites, (2) medium-sized neurites almost completely filled by electron-lucent vacuoles and (3) giant neurites. In general, only one giant neurite is seen on each section; this type displays the most synapses. Epithelial cells divide the ring nerve into compartments, each having a tendency to contain neurites of similar morphology. The number and arrangement of the compartments vary along the length of the ring nerve.

Significant photoreceptor rescue by treatment with a combination of antioxidants in an animal model for retinal degeneration.

The purpose of this study was to investigate the presence of oxidative DNA damage in the photoreceptors of the rd1 mouse, an animal model for retinitis pigmentosa, and to determine if antioxidants could delay the progress of photoreceptor cell death. Retinas of rd1 mice and congenic wild type controls were examined for DNA oxidation and fragmentation. To study the rescue effect of antioxidants on retinal degeneration, rd1 retinas were studied in vitro and in vivo using lutein, zeaxanthin, alpha lipoic acid and reduced l-glutathione. For the in vitro studies, antioxidants were added to the culture medium. For the in vivo studies, postnatal day (PN3) pups of rd1 mice were fed antioxidants either individually or in combination and control rd1 animals received vehicle alone. Histological evaluation was performed using hematoxylin/eosin and avidin staining, as well as terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Many of the rd1 rod photoreceptors at PN11 displayed oxidative DNA damage and TUNEL positive reaction which co-localized in a subset of rod photoreceptors. Avidin-labeled rod photoreceptors were more abundant than the TUNEL positive photoreceptors of the rd1 mouse, indicating that oxidative DNA damage precedes fragmentation. The number of TUNEL positive and avidin positive cells was considerably decreased upon treatment with the combination of the antioxidants. Rescue of rd1 photoreceptors was significant at PN18 and PN17, respectively, in the in vitro and in vivo studies. In conclusion individual antioxidants had no significant rescue effect but the combination slowed down the rd1 rod photoreceptor degeneration, indicating an additive or synergistic effect.

Bilaterally symmetrical rhopalial nervous system of the box jellyfish Tripedalia cystophora.

Cubomedusae, or box jellyfish, have the most elaborate visual system of all cnidarians. They have 24 eyes of four morphological types, distributed on four sensory structures called rhopalia. Box jellyfish also display complex, probably visually guided behaviors such as obstacle avoidance and fast directional swimming. Here we describe the strikingly complex and partially bilaterally symmetrical nervous system found in each rhopalium of the box jellyfish, Tripedalia cystophora, and present the rhopalial neuroanatomy in an atlas-like series of drawings. Discrete populations of neurons and commissures connecting the left and the right side along with two populations of nonneuronal cells were visualized using several different histochemical staining techniques and electron microscopy. The number of rhopalial nerve cells and their overall arrangement indicates that visual processing and integration at least partly happen within the rhopalia. The larger of the two nonneuronal cell populations comprises approximately 2,000 likely undifferentiated cells and may support a rapid cell turnover in the rhopalial nervous system.

Rhopalia are integrated parts of the central nervous system in box jellyfish.

In cubomedusae, the central nervous system (CNS) is found both in the bell (the ring nerve) and in the four eye-bearing sensory structures (the rhopalia). The ring nerve and the rhopalia are connected via the rhopalial stalks and examination of the structure of the rhopalial stalks therefore becomes important when trying to comprehend visual processing. In the present study, the rhopalial stalk of the cubomedusae Tripedalia cystophora has been examined by light microscopy, transmission electron microscopy, and electrophysiology. A major part of the ring nerve is shown to continue into the stalk and to contact the rhopalial neuropil directly. Ultrastructural analysis of synapse distribution in the rhopalial stalk has failed to show any clustering, which indicates that integration of the visual input is probably spread throughout the CNS. Together, the results indicate that cubomedusae have one coherent CNS including the rhopalia. Additionally, a novel gastrodermal nerve has been found in the stalk; this nerve is not involved in visual processing but is likely to be mechanosensory and part of a proprioceptory system.

Decreased glutathione transferase levels in rd1/rd1 mouse retina: replenishment protects photoreceptors in retinal explants.

Currently much attention is focused on glutathione S transferase (GST)-induced suppression of apoptosis. The objective of our studies was therefore to see if GST isoenzymes rescue photoreceptors in retinal explants from rd1/rd1 mice, in which photoreceptors degenerate rapidly. Eyes from C3H rd1/rd1 and +/+ mice were collected at various time points between postnatal day (PN) 2 and PN28. Localization and content of alpha-GST and mu-GST was investigated by immunofluorescence and semi-quantitative Western blot analysis, respectively. In addition, PN2 and PN7 retinal explants were cultured till PN28, during which they were treated with 10 ng/ml alpha-GST or mu-GST. The spatiotemporal expression of both GST isoforms was closely similar: early presence in ganglion cell layer after which staining became restricted to Muller cells (particularly in the endfeet) and horizontal cell fibers in both rd1/rd1 and +/+. Doublets of alpha-GST and mu-GST were detected by Western blot analysis. Densitometry of these bands indicated steady reduction of alpha-GST content in rd1/rd1 retina starting from the second postnatal week. When alpha-GST and mu-GST were added exogenously to rd1/rd1 explants, photoreceptor rescue was produced that was more prominent in PN2 than in PN7 explants and more effective by alpha-GST than mu-GST. We propose that alpha-GST neuroprotection is mediated by reduction of tissue oxidative stress.

Search for extraterrestrial point sources of neutrinos with AMANDA-II.

We present the results of a search for point sources of high-energy neutrinos in the northern hemisphere using AMANDA-II data collected in the year 2000. Included are flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic-ray-induced atmospheric neutrinos and misreconstructed downgoing cosmic-ray muons reveals no statistically significant neutrino point sources. We show that AMANDA-II has achieved the sensitivity required to probe known TeV gamma-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and gamma-ray fluxes are equal.

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector.

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

Do Japanese and Swedish peptic ulcer patients respond differently to Helicobacter pylori eradication therapies and what are their histological features?

BACKGROUND: As a consequence of gastric histological differences, Japanese and Swedish peptic ulcer (PU) patients may respond differently to Helicobacter pylori eradication therapies. METHODS: The study was single-blind and compared four eradication therapies in Japanese and Swedish patients with healed gastric (GU) or duodenal (DU) ulcer. Swedish patients received either (a) omeprazole+clarithromycin (OC, where O = 20 mg, C = 500 mg) for 2 weeks, or triple therapy with (b) omeprazole + amoxicillin + clarithromycin (OAC-L where O = 20mg, A = 1 g, C = 250 mg); (c) OAC-H (where O = 20 mg, A-1 g, C-500 mg); or (d) omeprazole + metronidazole + clarithromycin (OMC, where O = 20 mg, M = 400 mg, C = 250 mg) for 1 week. Antibiotic doses were weight-adjusted downwards in Japanese patients. H. pylori was assessed using the urea breath test (UBT), histology and culture pre-entry, with UBT being repeated 4 and 8 weeks after stopping treatment. Histology and culture were repeated if the UBT was positive post-therapy. RESULTS: Recruitment included 120 patients from Japan (43 GU, 61 DU, 16 GU+DU) and 120 from Sweden (119 DU, 1 GU+DU). There were 26 exclusions from a FAS analysis due to H. pylori negativity (14), no drug administration (7) or no data after visit 1 (5). Eradication rates (FAS) from Japan were (a) 63%, (b) 93%, (c) 96% or (d) 96%, and for Sweden (a) 92%, (b) 86%, (c) 93% or (d) 96%. Dual therapy was less effective in patients with gastric atrophy associated with GU disease. Tolerability was good in all treatment groups, with no serious adverse events. CONCLUSION: Triple therapies were safe and effective for H. pylori eradication in Japanese and Swedish peptic ulcer patients. Dual therapy was significantly less effective in the Japanese patients, half of whom had a history of GU and more abnormal histology than in the Swedish patients, all of whom had DU.

Comparison of gastric histology among Swedish and Japanese patients with peptic ulcer and Helicobacter pylori infection.

BACKGROUND: The natural course of Helicobacter pylori gastritis may vary between different ethnic groups. Gastric histopathology and the occurrence of H. pylori organisms in the stomach were investigated in healed duodenal (DU) and gastric (GU) ulcer patients recruited in Sweden (S) and Japan (J) in an identical trial. METHODS: In 203 patients (JGU = 39, JDU = 55, SDU = 109), various morphological gastritis variables and H. pylori were assessed from biopsy specimens obtained using a specific sampling protocol and interpreted according to guidelines of the updated Sydney grading system. RESULTS: The ratio of GU:DU was observed to be very different between the recruited Japanese (39:55) and Swedish (0:109) patients. A comparison of data from SDU and JDU showed that the prevalence of H. pylori infection and the antral predominant gastritis demonstrated by both SDU and JDU were essentially identical. A comparison of data from JDU and JGU demonstrated a greater prevalence of H. pylori infection in the antrum, but not corpus, of JDU compared to JGU patients. The prevalence of atrophy and intestinal metaplasia was higher in both the antrum and corpus of JGU compared to JDU in all patients. CONCLUSIONS: The site specified biopsy methodology and standardized interpretation criteria utilized in this study clearly show that the histotopographic profile of Swedish and Japanese DU patients is essentially the same.

Comparison of Gastric Histology Among Swedish and Japanese Patients with Peptic Ulcer and <emph type="2">Helicobacter pylori</emph> Infection.

BACKGROUND: The natural course of Helicobacter pylori gastritis may vary between different ethnic groups. Gastric histopathology and the occurrence of H. pylori organisms in the stomach were investigated in healed duodenal (DU) and gastric (GU) ulcer patients recruited in Sweden (S) and Japan (J) in an identical trial. METHODS: In 203 patients (JGU = 39, JDU = 55, SDU = 109), various morphological gastritis variables and H. pylori were assessed from biopsy specimens obtained using a specific sampling protocol and interpreted according to guidelines of the updated Sydney grading system. RESULTS: The ratio of GU:DU was observed to be very different between the recruited Japanese (39:55) and Swedish (0:109) patients. A comparison of data from SDU and JDU showed that the prevalence of H. pylori infection and the antral predominant gastritis demonstrated by both SDU and JDU were essentially identical. A comparison of data from JDU and JGU demonstrated a greater prevalence of H. pylori infection in the antrum, but not corpus, of JDU compared to JGU patients. The prevalence of atrophy and intestinal metaplasia was higher in both the antrum and corpus of JGU compared to JDU in all patients. CONCLUSIONS: The site specified biopsy methodology and standardized interpretation criteria utilized in this study clearly show that the histotopographic profile of Swedish and Japanese DU patients is essentially the same.

Detection of mutations in exon 8 of TP53 by temperature gradient 96-capillary array electrophoresis.

Various capillary electrophoresis applications have increasingly been utilized in mutation detection. Separation of two species is either based on secondary structure or differences in melting of DNA due to the mutation. Detection of the mutant is based on its mobility difference in the sieving matrix. We have adapted a regular 96-capillary sequencing instrument, the MegaBACE 1000, for mutation detection based on thermodynamic stability and mobility shift during electrophoresis. Denaturation of the lower melting domain of the DNA was achieved with a gradually decreasing temperature gradient in combination with a chemical denaturant. Samples were analyzed for mutants in exon 8 of the TP53 genefrom tumor samples and controls. Genomic DNA was PCR-amplified with one fluorescein labeled primer and one GC-clamped primer, diluted in water, and analyzed by temperature gradient 96-capillary array electrophoresis. Tumor samples and PCR reconstruction experiment samples were resolved by capillary gel electrophoresis under appropriate temperature gradient denaturing conditions. Ninety-six samples were analyzed in one run, with an analysis time of 30 min and a sensitivity to detect mutated alleles in wild-type background down to 0.4%. The technique proved to be robust, in that the gradient compensatesfor temperature differences within the capillary chamber; thus, each capillary will pass through the optimal separating conditions around the theoretical melting temperature for TP53 exon 8, separating homoduplexes and heteroduplexes. This technique is applicable to any sequence previously analyzed by DNA melting gel techniques or sequences harboring iso-melting domains of 100-120 bp.

Effect of profound acid suppression in functional dyspepsia: a double-blind, randomized, placebo-controlled trial.

BACKGROUND: Functional dyspepsia (FD) is defined as persistent or recurrent pain/discomfort centred in the upper abdomen, where no structural explanation for the symptoms is found. The role of drug treatment remains controversial. The aim in this study was to evaluate the effect of omeprazole 20 mg twice daily (b.i.d) and to test methods for symptom assessment. METHODS: 197 patients fulfilling the criteria for FD were randomly allocated to double-blind treatment with omeprazole 20 mg b.i.d (n = 100) or placebo (n = 97) for 14 days. Patients with a known gastrointestinal disorder or with main symptoms indicating gastro-oesophageal reflux disease or irritable bowel syndrome were excluded. Helicobacter pylori testing and 24-h intra-oesophageal 24-h pH-metry were performed before randomization. The patients recorded dyspeptic symptoms on diary cards. RESULTS: A stringent endpoint, 'complete symptom relief on the last day of treatment', was the primary efficacy variable. For the APT cohort, this was achieved in 29.0% and 17.7% on omeprazole and placebo, respectively (95% CI of difference (11.3%): -0.4%-23.0%, P = 0.057). Similar figures in the PP cohort were 31.0% and 15.5%, respectively (95% Cl of difference (15.5%): 3.2%-27.7%, P = 0.018). The benefit of omeprazole in the PP cohort was confirmed by secondary endpoints such as, no dyspeptic symptoms on the last 2 days of treatment and overall treatment response. H. pylori status and the level of oesophageal acid exposure did not significantly influence the response to therapy. CONCLUSION: A subset of patients with FD will respond to therapy with omeprazole.