Impacts of ocean acidification and warming on post-larval growth and metabolism in two populations of the great scallop (Pecten maximus L.)

Ocean acidification and warming are key stressors for many marine organisms. Some organisms display physiological acclimatisation or plasticity, but this may vary across species ranges, especially if populations are adapted to local climatic conditions. Understanding how acclimatisation potential varies among populations is therefore important in predicting species responses to climate change. We carried out a common garden experiment to investigate how different populations of the economically important great scallop (Pecten maximus) from France and Norway responded to variation in temperature and pCO2 concentration. After acclimation, post-larval scallops (spat) were reared for 31 days at one of two temperatures (13°C and 19°C) under either ambient or elevated pCO2 (pH 8.0 and pH 7.7). We combined measures of proteomic, metabolic, and phenotypic traits to produce an integrative picture of how physiological plasticity varies between the populations. The proteome of French spat showed significant sensitivity to environmental variation, with 12 metabolic, structural and stress-response proteins responding to temperature and/or pCO2. Principal component analysis revealed seven energy metabolism proteins in French spat that were consistent with countering ROS stress under elevated temperature. Oxygen uptake in French spat did not change under elevated temperature, but increased under elevated pCO2. In contrast, Norwegian spat reduced oxygen uptake under both elevated temperature and pCO2. Metabolic plasticity seemingly allowed French scallops to maintain greater energy availability for growth than Norwegian spat. However, increased physiological plasticity and growth in French spat may come at a cost, as French (but not Norwegian) spat showed reduced survival under elevated temperature.

Microbiota of the Digestive Glands and Extrapallial Fluids of Clams Evolve Differently Over Time Depending on the Intertidal Position

The Manila clam (Ruditapes philippinarum) is the second most exploited bivalve in the world but remains threatened by diseases and global changes. Their associated microbiota play a key role in their fitness and acclimation capacities. This study aimed at better understanding the behavior of clam digestive glands and extrapallial fluids microbiota at small, but contrasting spatial and temporal scales. Results showed that environmental variations impacted clam microbiota differently according to the considered tissue. Each clam tissue presented its own microbiota and showed different dynamics according to the intertidal position and sampling period. Extrapallial fluids microbiota was modified more rapidly than digestive glands microbiota, for clams placed on the upper and lower intertidal position, respectively. Clam tissues could be considered as different microhabitats for bacteria as they presented different responses to small-scale temporal and spatial variabilities in natural conditions. These differences underlined a more stringent environmental filter capacity of the digestive glands.

The marine intertidal zone shapes oyster and clam digestive bacterial microbiota

Digestive microbiota provide a wide range of beneficial effects on host physiology and are therefore likely to play a key role in marine intertidal bivalve ability to acclimatize to the intertidal zone. This study investigated the effect of intertidal levels on the digestive bacterial microbiota of oysters (Crassostrea gigas) and clams (Ruditapes philippinarum), two bivalves with different ecological niches. Based on 16S rRNA region sequencing, digestive glands, seawater and sediments harbored specific bacterial communities, dominated by operational taxonomic units assigned to the Mycoplasmatales,Desulfobacterales and Rhodobacterales orders, respectively. Field implantation modified digestive bacterial microbiota of both bivalve species according to their intertidal position. Rhodospirillales and Legionellales abundances increased in oysters and clams from the low intertidal level, respectively. After a 14-day depuration process, these effects were still observed, especially for clams, while digestive bacterial microbiota of oysters were subjected to more short-term environmental changes. Nevertheless, 3.5 months stay on an intertidal zone was enough to leave an environmental footprint on the digestive bacterial microbiota, suggesting the existence of autochthonous bivalve bacteria. When comparing clams from the three intertidal levels, 20% of the bacterial assemblage was shared among the levels and it was dominated by an operational taxonomic unit affiliated to the Mycoplasmataceae and Spirochaetaceae families.

Bioactive extracellular compounds produced by the dinoflagellate Alexandrium minutum are highly detrimental for oysters

Blooms of the dinoflagellate Alexandrium spp., known as producers of paralytic shellfish toxins (PSTs), are regularly detected on the French coastline. PSTs accumulate into harvested shellfish species, such as the Pacific oyster Crassostrea gigas, and can cause strong disorders to consumers at high doses. The impacts of Alexandrium minutum on C. gigas have often been attributed to its production of PSTs without testing separately the effects of the bioactive extracellular compounds (BECs) with allelopathic, hemolytic, cytotoxic or ichthyotoxic properties, which can also be produced by these algae. The BECs, still uncharacterized, are excreted within the environment thereby impacting not only phytoplankton, zooplankton but also marine invertebrates and fishes, without implicating any PST. The aim of this work was to compare the effects of three strains of A. minutum producing either only PSTs, only BECs, or both PSTs and BECs, on the oyster C. gigas. Behavioral and physiological responses of oysters exposed during 4 days were monitored and showed contrasted behavioral and physiological responses in oysters supposedly depending on produced bioactive substances. The non-PST extracellular-compound-producing strain primarily strongly modified valve-activity behavior of C. gigas and induced hemocyte mobilization within the gills, whereas the PST-producing strain caused inflammatory responses within the digestive gland and disrupted the daily biological rhythm of valve activity behavior. BECs may therefore have a significant harmful effect on the gills, which is one of the first organ in contact with the extracellular substances released in the water by A. minutum. Conversely, the PSTs impact the digestive gland, where they are released and mainly accumulated, after degradation of algal cells during digestion process of bivalves. This study provides a better understanding of the toxicity of A. minutum on oyster and highlights the significant role of BECs in this toxicity calling for further chemical characterization of these substances.

Effects of bioactive extracellular compounds and paralytic shellfish toxins produced by Alexandrium minutum on growth and behaviour of juvenile great scallops Pecten maximus

Dinoflagellates of the genus Alexandrium are a major cause of harmful algal blooms (HABs) that have increasingly disrupted coastal ecosystems for the last several decades. Microalgae from the genus Alexandrium are known to produce paralytic shellfish toxins (PST) but also bioactive extracellular compounds (BEC) that can display cytotoxic, allelopathic, ichtyotoxic or haemolytic effects upon marine organisms. The objective of this experimental study was to assess the effects of PST and BEC produced by A. minutum upon juvenile great scallops Pecten maximus. Scallops were exposed for one week to two different strains of A. minutum, the first producing both PST and BEC and the second producing only BEC. Escape response to starfish, daily shell growth, histological effects, and accumulation of PST were recorded after one week of exposure, and after two subsequent weeks of recovery. Daily shell growth was delayed three days in scallops exposed to the BEC-producing A. minutum strain, probably during the three first days of exposure. An increase of reaction time to predators was observed in scallops exposed to the BEC condition, suggesting that BEC may have altered sensing processes. Scallops exposed to PST displayed a less-efficient escape response and muscular damage which could reflect the effects of paralytic toxins upon the nervous system of scallops. This study demonstrates contrasting effects of the distinct toxic compounds produced by A. minutum upon marine bivalves, thus highlighting the importance to better characterize these extracellular, bioactive compounds to better understand responses of other marine organisms.

Long dsRNAs promote an anti-viral response in Pacific oyster hampering ostreid herpesvirus 1 replication

Double stranded RNA-mediated genetic interference (RNAi) is a widely used reverse genetic tool for determining the loss-of-function phenotype of a gene. Here, the possible induction of an immune response by long dsRNA was tested in a marine bivalve, i.e. Crassostrea gigas, as well as the specific role of the subunit 2 of the nuclear factor κB inhibitor (IκB2). This gene is a candidate of particular interest for functional investigations in the context of massive mortality oyster events as Cg-IκB2 mRNA levels exhibited significant variation depending on the amount of ostreid herpesvirus 1 (OsHV-1) DNA detected. In the present study, dsRNAs targeting Cg-IκB2 and Green Fluorescence Protein genes were injected in vivo into oysters before being challenged by OsHV-1. Survival appeared close to 100% in both dsRNA injected conditions associated with a low detection of viral DNA and a low expression of a panel of 39 OsHV-1 genes as compared to infected control. Long dsRNA molecules, both Cg-IκB2- and GFP-dsRNA, may have induced an anti-viral state controlling the OsHV-1 replication and precluding the understanding of the Cg-IκB2 specific role. Immune-related genes including Cg-IκB1, Cg-Rel1, Cg-IFI44, Cg-PKR, and Cg-IAP appeared activated in dsRNA-injected condition potentially hampering viral replication and thus conferring a better resistance to OsHV-1 infection. We revealed that long dsRNA-mediated genetic interference triggered an anti-viral state in the oyster, emphasizing the need of new reverse genetics tools for assessing immune gene function and avoiding off-target effects in bivalves.

Exposure to the toxic dinoflagellate Alexandrium catenella modulates juvenile oyster Crassostrea gigas hemocyte variables subjected to different biotic conditions

The Pacific oyster Crassostrea gigas is an important commercial species cultured throughout the world. Oyster production practices often include transfers of animals into new environments that can be stressful, especially at young ages. This study was undertaken to determine if a toxic Alexandrium bloom, occurring repeatedly in French oyster beds, could modulate juvenile oyster cellular immune responses (i.e. hemocyte variables). We simulated planting on commercial beds by conducting a cohabitation exposure of juvenile, "specific pathogen-free" (SPF) oysters (naïve from the environment) with previously field-exposed oysters to induce interactions with new microorganisms. Indeed, toxic Alexandrium spp. exposures have been reported to modulate bivalve interaction with specific pathogens, as well as physiological and immunological variables in bivalves. In summary, SPF oysters were subjected to an artificial bloom of Alexandrium catenella, simultaneously with a cohabitation challenge. Exposure to A. catenella, and thus to the paralytic shellfish toxins (PSTs) and extracellular bioactive compounds produced by this alga, induced higher concentration, size, complexity and reactive oxygen species (ROS) production of circulating hemocytes. Challenge by cohabitation with field-exposed oysters also activated these hemocyte responses, suggesting a defense response to new microorganism exposure. These hemocyte responses to cohabitation challenge, however, were partially inhibited by A. catenella exposure, which enhanced hemocyte mortality, suggesting either detrimental effects of the interaction of both stressors on immune capacity, or the implementation of an alternative immune strategy through apoptosis. Indeed, no infection with specific pathogens (herpesvirus OsHV-1 or Vibrio aesturianus) was detected. Additionally, lower PST accumulation in challenged oysters suggests a physiological impairment through alteration of feeding-related processes. Overall, results of this study show that a short-term exposure to A. catenella combined with an exposure to a modified microbial community inhibited some hemocyte responses, and likely compromised physiological condition of the juvenile oysters.

Non-additive effects of ocean acidification in combination with warming on the larval proteome of the Pacific oyster, Crassostrea gigas

Increasing atmospheric carbon dioxide results in ocean acidification and warming, significantly impacting marine invertebrate larvae development. We investigated how ocean acidification in combination with warming affected D-veliger larvae of the Pacific oyster Crassostrea gigas. Larvae were reared for 40h under either control (pH8.1, 20 °C), acidified (pH7.9, 20 °C), warm (pH8.1, 22 °C) or warm acidified (pH7.9, 22 °C) conditions. Larvae in acidified conditions were significantly smaller than in the control, but warm acidified conditions mitigated negative effects on size, and increased calcification. A proteomic approach employing two-dimensional electrophoresis (2-DE) was used to quantify proteins and relate their abundance to phenotypic traits. In total 12 differentially abundant spots were identified by nano-liquid chromatography-tandem mass spectrometry. These proteins had roles in metabolism, intra- and extra-cellular matrix formations, stress response, and as molecular chaperones. Seven spots responded to reduced pH, four to increased temperature, and six to acidification and warming. Reduced abundance of proteins such as ATP synthase and GAPDH, and increased abundance of superoxide dismutase, occurred when both pH and temperature changes were imposed, suggesting altered metabolism and enhanced oxidative stress. These results identify key proteins that may be involved in the acclimation of C. gigas larvae to ocean acidification and warming.

SIGNIFICANCE

Increasing atmospheric CO2 raises sea surface temperatures and results in ocean acidification, two climatic variables known to impact marine organisms. Larvae of calcifying species may be particularly at risk to such changing environmental conditions. The Pacific oyster Crassostrea gigas is ecologically and commercially important, and understanding its ability to acclimate to climate change will help to predict how aquaculture of this species is likely to be impacted. Modest, yet realistic changes in pH and/or temperature may be more informative of how populations will respond to contemporary climate change. We showed that concurrent acidification and warming mitigates the negative effects of pH alone on size of larvae, but proteomic analysis reveals altered patterns of metabolism and an increase in oxidative stress suggesting non-additive effects of the interaction between pH and temperature on protein abundance. Thus, even small changes in climate may influence development, with potential consequences later in life.

Randomised clinical trial: the 5-HT4 agonist revexepride in patients with gastro-oesophageal reflux disease who have persistent symptoms despite PPI therapy

BACKGROUND

A substantial proportion of patients with gastro-oesophageal reflux disease (GERD) have only a partial response to proton pump inhibitor (PPI) therapy. Prokinetic drugs may improve reflux symptoms by enhancing oesophageal motility and gastric emptying.

AIM

To evaluate the effect of revexepride, a novel prokinetic 5-hydroxytryptamine type 4 (5-HT4 ) receptor agonist, compared with placebo, in patients with GERD who have a partial response to PPIs.

METHODS

A phase 2b, double-blind, parallel-group study was conducted, in which patients were randomised to one of three revexepride treatment groups (0.1, 0.5 and 2.0 mg three times daily) or placebo (1:1:1:1 ratio). Daily e-diary data captured patients' symptoms over an 8-week treatment period. The primary efficacy outcome was the weekly percentage of regurgitation-free days in the second half of the study (weeks 5-8).

RESULTS

In total, 480 patients were randomised and 477 received treatment (mean age 47.9 years; 61% women). The mean percentage of regurgitation-free days increased from baseline (range, 15.0-18.8%) to week 8 (62.3-70.5%) in all four study arms; however, there were no statistically significant differences in this change between placebo and the three treatment arms. No dose-dependent relationship in treatment effect was observed for any of the study endpoints. The incidence of treatment-emergent adverse events (TEAEs) was revexepride dose-dependent. Only one serious TEAE occurred and none resulted in death.

CONCLUSIONS

Revexepride was no more effective than placebo in controlling regurgitation in patients with GERD symptoms partially responsive to PPIs. Revexepride was well tolerated. ClinicalTrials.gov Identifier: NCT01472939.

Integrative study of physiological changes associated with bacterial infection in Pacific oyster larvae

Background

Bacterial infections are common in bivalve larvae and can lead to significant mortality, notably in hatcheries. Numerous studies have identified the pathogenic bacteria involved in such mortalities, but physiological changes associated with pathogen exposure at larval stage are still poorly understood. In the present study, we used an integrative approach including physiological, enzymatic, biochemical, and molecular analyses to investigate changes in energy metabolism, lipid remodelling, cellular stress, and immune status of Crassostrea gigas larvae subjected to experimental infection with the pathogenic bacteria Vibrio coralliilyticus.

Findings

Our results showed that V. coralliilyticus exposure induced (1) limited but significant increase of larvae mortality compared with controls, (2) declined feeding activity, which resulted in energy status changes (i.e. reserve consumption, β-oxidation, decline of metabolic rate), (3) fatty acid remodeling of polar lipids (changes in phosphatidylinositol and lysophosphatidylcholine composition`, non-methylene–interrupted fatty acids accumulation, lower content of major C₂₀ polyunsaturated fatty acids as well as activation of desaturases, phospholipase and lipoxygenase), (4) activation of antioxidant defenses (catalase, superoxide dismutase, peroxiredoxin) and cytoprotective processes (heat shock protein 70, pernin), and (5) activation of the immune response (non-self recognition, NF-κκ signaling pathway, haematopoiesis, eiconosoids and lysophosphatidyl acid synthesis, inhibitor of metalloproteinase and antimicrobial peptides).

Conclusion

Overall, our results allowed us to propose an integrative view of changes induced by a bacterial infection in Pacific oyster larvae, opening new perspectives on the response of marine bivalve larvae to infections.

Clinical trial: evaluation of gastric acid suppression with three doses of immediate-release esomeprazole in the fixed-dose combination of PN 400 (naproxen/esomeprazole magnesium) compared with naproxen 500 mg and enteric-coated esomeprazole 20 mg: a randomized, open-label, Phase I study in healthy volunteers

BACKGROUND

PN 400 is a fixed-dose combination formulated to provide sequential delivery of immediate-release (IR) esomeprazole and enteric-coated (EC) naproxen.

AIM

To evaluate gastric acid suppression with three doses of esomeprazole in PN 400 compared with EC esomeprazole 20 mg.

METHODS

In this Phase I, randomized, open-label study, 28 healthy adults received PN 400 b.d. (naproxen 500 mg plus esomeprazole 10, 20 and 30 mg) and non-EC naproxen 500 mg b.d. plus EC esomeprazole 20 mg o.d., each for 9 days in a crossover fashion. The primary endpoint was percentage of time on day 9 that intragastric pH was >4.0; secondary endpoints included pharmacokinetics and safety.

RESULTS

Day 9 percentage of time where intragastric pH was >4.0 was 76.5%, 71.4%, 40.9% and 56.9% [corrected] for PN 400 containing 30, 20 and 10 mg esomeprazole, and naproxen plus esomeprazole 20 mg respectively. This was significantly greater for PN 400 containing 30 and 20 mg esomeprazole vs. naproxen plus esomeprazole 20 mg (95% CI: 13.0-26.0 and 7.8-20.7 respectively). The pharmacokinetics of PN 400 were consistent with its formulation. No serious adverse events occurred.

CONCLUSION

PN 400 containing 20 mg esomeprazole was the lowest dose to achieve gastric acid suppression comparable to EC esomeprazole 20 mg and was selected for further evaluation.

Effects of a single dose of rabeprazole 20 mg and pantoprazole 40 mg on 24-h intragastric acidity and oesophageal acid exposure: a randomized study in gastro-oesophageal reflux disease patients with a history of nocturnal heartburn

BACKGROUND

Nocturnal heartburn is common in patients with gastro-oesophageal reflux disease (GERD).

AIM

To compare the effects of single doses of rabeprazole 20 mg and pantoprazole 40 mg on 24-h intragastric acidity and oesophageal acid exposure (OAE).

METHODS

A total of 52 subjects with GERD and a >or=6-month history of heartburn were randomized into a blinded, 2 x 2 crossover trial. Subjects' intragastric pH was monitored in two 48-h study periods with 6- to 13-day washout between periods. Patients received placebo on day 1, a single dose of rabeprazole 20 mg or pantoprazole 40 mg on day 2, and standardized meals throughout.

RESULTS

The mean percentage time with intragastric pH >4 was significantly greater with rabeprazole vs. pantoprazole for the 24-h postdose interval (44.0% vs. 32.8%; P < 0.001). Significant differences were observed in the daytime (51.0% vs. 42.2%; P < 0.001) and nighttime (32.0% vs. 16.9%; P < 0.001). Rabeprazole was also significantly superior in other intragastric pH parameters. There was no statistical difference for OAE between treatments.

CONCLUSIONS

In GERD patients with nocturnal heartburn, rabeprazole 20 mg was significantly more effective than pantoprazole 40 mg in percentage time with intragastric pH >4 during the nighttime, daytime, and 24-h periods. Differences between treatments in OAE were not demonstrated. This trial is registered with http://clinicaltrials.gov, number NCT00237367.

Techniques for delivery of arachidonic acid to pacific oyster, Crassostrea gigas, spat

The present study tested two techniques for dietary supplementation of Crassostrea gigas spat with PUFA, such as arachidonic acid (AA). The first technique consisted of a preliminary enrichment and growth of an algal concentrate (T-ISO, Isochrysis sp.) with AA dissolved in an ethanol solution, the whole culture then being fed to the spat. This enrichment increased the AA weight percentage in T-ISO neutral and polar lipids from 0.6 to 22.4% and from 0.4 to 6.8%, respectively. The second delivery technique was direct addition separately of free AA dissolved in ethanol solution and algal concentrate (T-ISO + AA) to the spat-rearing tank. To test the efficiency of these delivery techniques, oyster spat were supplemented with AA-enriched T-ISO, T-ISO + AA, and T-ISO alone. The possible biological impacts of these dietary treatments were assessed by measuring growth, condition index, and TAG content of oyster spat. Dry weight and condition index of spat fed AA-enriched T-ISO decreased by 24 and 49%, respectively, after 26 d of feeding; basically, TAG content declined 88% after 34 d of conditioning. When AA was added directly to seawater, spat growth and condition index were comparable with those of oysters fed T-ISO alone. AA incorporation in oyster tissues was assessed by analysis of the FA compositions in both neutral and polar lipid fractions. After 34 d, AA content in neutral lipids reached 7 and 11.7% in the spat fed, respectively, AA-enriched T-ISO and T-ISO + AA, as compared with 1.1% in spat fed only T-ISO. AA incorporation was greater in polar lipids than in neutral lipids, reaching 7.8 and 12.5% in spat fed AA-enriched T-ISO and T-ISO + AA, respectively. A direct addition of PUFA along with the food supply represents an effective and promising means to supplement PUFA to oyster spat.

Review article: relief of symptoms in gastric acid-related diseases--correlation with acid suppression in rabeprazole treatment

Symptom relief is one of the key goals in the management of gastric acid-related disorders such as gastro-oesophageal reflux disease (GERD), including nonerosive reflux disease (NERD), and duodenal and gastric ulcer. Whereas heartburn and regurgitation are classic symptoms of GERD, duodenal and gastric ulcers are associated with epigastric pain. The relationship between gastric acid and the presence of symptoms correlates well in GERD and duodenal ulcer, but not in gastric ulcer and NERD. Nevertheless, in all these disorders, gastric acid is considered a key pathogenic element, and acid suppression remains central to therapy. With their profound, prolonged effect on acid inhibition, proton pump inhibitors are considered the first-choice therapy for these disorders. Rabeprazole is a newer generation proton pump inhibitor that suppresses the gastric proton pump and acid secretion more rapidly than does omeprazole, lansoprazole or pantoprazole. In clinical trial settings, rabeprazole provided fast and sustained symptom relief, which can help ensure patient acceptance of therapy and aid in patient compliance.

An enema formulation of alicaforsen, an antisense inhibitor of intercellular adhesion molecule-1, in the treatment of chronic, unremitting pouchitis

BACKGROUND

Pouchitis is the major long-term complication of ileal pouch-anal anastomosis for ulcerative colitis. The incidence of pouchitis is as high as 50% several years after surgery. Two-thirds of pouchitis patients suffer recurrence. Of those who recur, one-quarter suffer from chronic, unremitting pouchitis. Current treatments for this disorder are disappointing.

AIM

To determine whether a topically administered enema formulation of ISIS 2302 (alicaforsen), an antisense inhibitor of intercellular adhesion molecule-1, can improve the clinical symptoms, endoscopic mucosal appearance and mucosal histology in patients with chronic, unremitting pouchitis, a disorder in which this molecule is over-expressed.

METHODS

In an open-label, uncontrolled study, 12 patients with chronic, unremitting pouchitis were treated with 240 mg alicaforsen antisense enema nightly for 6 weeks. Clinical evaluation and endoscopy were performed at baseline and at weeks 3, 6 and 10. Pouchoscopy with biopsy was carried out at baseline and at weeks 6 and 10. The primary end-point was the reduction from baseline of the Pouchitis Disease Activity Index (PDAI) at week 6. Secondary end-points included the PDAI at week 10. Safety was evaluated by analysing the adverse events, vital signs and laboratory parameters.

RESULTS

After 6 weeks of nightly alicaforsen enema, a statistically significant (n = 12, P = 0.001) reduction in the PDAI from baseline (11.42) to week 6 (6.83) was observed. Mean reductions in the endoscopy sub-score from baseline (5.25) to week 3 (3.08) and week 6 (2.58) were statistically significant (P = 0.0039 and P = 0.0005, respectively). The mean reductions in clinical symptom sub-score from baseline (3.75) to week 3 (2.33) and week 6 (2.25) were also statistically significant (P = 0.0156 and P = 0.0117, respectively). Ten of the 12 patients achieved a mucosal appearance score of 0 or 1 at endoscopy. Five of the 12 patients (42%) had a non-statistically significant decrease in the histology component of their PDAI from baseline to week 6. By week 6, seven of the 12 patients (58%) were in remission, as defined by PDAI < 7, with a mean decrease from baseline in PDAI score of six points. The alicaforsen enemas were well tolerated and no serious side-effects were noted.

CONCLUSIONS

Antisense enema to intercellular adhesion molecule-1 is safe and well tolerated. In an open-label trial, it appeared to improve the PDAI score, clinical symptoms and endoscopic mucosal appearance. It may also improve the histology. In the light of the responses observed in this trial, a randomized, placebo-controlled trial is warranted.

Effect of a mono-specific algal diet on immune functions in two bivalve species--Crassostrea gigas and Ruditapes philippinarum

The impact of diets upon the fatty acid composition of haemocyte polar lipids and consequently upon immune parameters has been tested in the oyster Crassostrea gigas and the clam Ruditapes philippinarum. Oysters and clams were fed each of three cultured algae: Chaetoceros calcitrans, which is rich in 20:5(n-3) and 20:4(n-6) and poor in 22:6(n-3) fatty acids; T-Iso (Isochrysis sp.), which is rich in 22:6(n-3) and deficient in 20:5(n-3) and 20:4(n-6); and Tetraselmis suecica, which is deficient in 22:6(n-3) and contains only small amounts of 20:5(n-3) and 20:4(n-6). Fatty acid composition of haemocyte polar lipids was greatly affected by the diet. Oysters and clams fed C. calcitrans maintained a higher proportion of 20:5(n-3) and 20:4(n-6) in their haemocyte polar lipids, while these polyunsaturated fatty acids decreased drastically for animals fed T-Iso. However, the T-Iso diet maintained 22:6(n-3) in haemocyte polar lipids of both species. Higher 20:5(n-3) and 20:4(n-6) contents in diets appeared to have a positive effect upon total haemocyte count, granulocyte percentage, phagocytic rate and oxidative activity of clam haemocytes. Similarly, a positive effect of 20:5(n-3) on oxidative activity of oyster haemocytes was observed but to a lesser extent than in clams. Interestingly, when oyster haemocytes are submitted to a stressful condition, a positive effect of a higher dietary 22:6(n-3) content on the phagocytic rate was noticed.

A randomized, double-blind, placebo-controlled trial of tegaserod in female patients suffering from irritable bowel syndrome with constipation

BACKGROUND

Irritable bowel syndrome is a common functional gastrointestinal disorder which affects up to 20% of the population, with a predominance in females.

AIM

To evaluate the efficacy and safety of tegaserod in female patients with irritable bowel syndrome characterized by symptoms of abdominal pain/discomfort and constipation.

METHODS

In a randomized, double-blind, multicentre study, 1519 women received either tegaserod, 6 mg b.d. (n = 767), or placebo (n = 752) for 12 weeks, preceded by a 4-week baseline period without treatment and followed by a 4-week open withdrawal period. The primary efficacy evaluation was the patient's symptomatic response as measured by the Subject's Global Assessment of Relief. Other efficacy variables included abdominal pain/discomfort, bowel habits and bloating.

RESULTS

Tegaserod produced significant (P < 0.05) improvements in the Subject's Global Assessment of Relief and other efficacy variables. These improvements were seen within the first week, and were maintained throughout the treatment period. After withdrawal of treatment, the symptoms rapidly returned. Overall, tegaserod was well tolerated. Diarrhoea was the most frequent adverse event; however, this led to discontinuation in only 1.6% of tegaserod-treated patients.

CONCLUSIONS

Tegaserod, 6 mg b.d., produced rapid and sustained improvement of symptoms in female irritable bowel syndrome patients and was well tolerated.

Psychometric validation of a constipation symptom assessment questionnaire

BACKGROUND

Clinical management of constipation is complicated by the lack of a gold standard for evaluation of symptoms. A constipation symptom assessment instrument, the PAC-SYM, was developed to address the patient perspective on the disorder. Instrument content was based on literature review and results of focus groups.

METHODS

Two hundred and sixteen patients at nine sites participated in a 6-week psychometric evaluation of the PAC-SYM. The final instrument contained 12 items assigned to 3 subscales: stool symptoms, rectal symptoms, and abdominal symptoms. The psychometric properties of this final instrument were assessed.

RESULTS

Internal consistency and test-retest reliability of the final instrument was high (Cronbach's alpha = 0.89; intraclass correlation = 0.75). Concurrent validity was supported by the correlation with both subject and investigator constipation severity ratings (r= 0.68 and 0.72, respectively; P < 0.0001). Scores were moderately correlated with instruments measuring quality of life. Comparison of treatment responders with nonresponders showed the ability of the instrument to differentiate between groups on the basis of clinical severity (t = -6.12, P < 0.0001 ). Scores changed significantly over time among responders, indicating instrument responsiveness.

CONCLUSIONS

The PAC-SYM is internally consistent, reproducible under stable conditions, valid, and responsive to change and provides a comprehensive means to assess the effectiveness of treatment for constipation.

Meal type affects heartburn severity

This study compared heartburn severity, number of episodes, and changes in esophageal pH induced by three meals. Symptomatic volunteers consumed the following on different occasions: McDonald's Quarter Pounder, french fries, and chocolate shake; McDonald's Sausage Biscuit with Egg, cheese, raw onion, and chocolate milk; and Wendy's Chili and red wine. Increases in reflux episodes over baseline for the hamburger, sausage biscuit, and chili meals were 28.8 +/- 5.7, 36 +/- 5.5 and 43.7 +/- 8.8, respectively. The sausage biscuit and chili increased reflux compared to the hamburger (P < 0.05), but the chili did not differ statistically from the sausage biscuit meal. Onset and peak heartburn for the hamburger, sausage biscuit, and chili meals were 45 and 90, 30 and 120, and 15 and 150 min, respectively. Despite lower fat content, chili and red wine promoted more reflux and heartburn pain than the other meals, demonstrating the importance of meal selection in provocative meal studies.

Safety and efficacy of controlled-release mesalamine for maintenance of remission in ulcerative colitis. Pentasa UC Maintenance Study Group

This 12-month, double-blind, placebo-controlled study randomized 205 ulcerative colitis patients in remission to placebo or controlled-release mesalamine at 4 g/day for 12 months. Patients were stratified to either pancolitis or left-sided disease, based on previous diagnosis. Maintenance of remission was defined as a sigmoidoscopic index of < 5, less than five stools per day, and the absence of rectal bleeding. A significantly greater number of patients maintained remission on mesalamine 4 g/day than on placebo at each of five study visits, following the first one-month visit (P < 0.05). The estimated 12-month remission rates for the mesalamine group were 64% (38% for placebo, P = 0.0004). Baseline subgroups (disease location, time since last flare of active disease, and previous response to oral/rectal steroids or sulfasalazine) did not influence remission rates. Treatment-related adverse events were rare. Controlled-release mesalamine is a safe and efficacious single agent for maintaining remission of ulcerative colitis.

Nosocomial Legionnaires' disease. Epidemiologic demonstration of cooling towers as a source

Investigation of a recent outbreak of nosocomial legionnaires' disease--initially thought to be due to the documented presence of Legionella pneumophila in the hospital potable water--showed that aerosols from one or more cooling towers were the actual source of infection. From June 27 to Aug 25, 1983, nosocomial legionnaires' disease developed in 15 persons at a hospital in Rhode Island. Twelve (80%) of 15 case-patients occupied rooms in building 1, unit B, compared with eight (28%) of 29 control patients (odds ratio = 10.8; 95% confidence interval = 1.4 to 85.6). Subsequent investigation demonstrated that water in a cooling tower located 100 ft upwind of unit B was heavily contaminated with L pneumophila, serogroup 1, subgroup 1, 2, 4, 5. The same strain was isolated from nine of the patients and from the make-up water for the tower. Active surveillance during the ten months following decontamination of the cooling tower identified no additional cases of nosocomial legionnaires' disease, although the hospital potable water had not been treated. While recommendations have been made for controlling nosocomial legionnaires' disease by heating or hyperchlorination of hospital potable water, this outbreak demonstrates the importance of an adequate epidemiologic-environmental investigation in choosing the appropriate control strategy.

Pasteurella multocida bacteremia associated with peritonitis and cirrhosis

Pasteurella multocida has been the etiologic agent in at least three cases of "spontaneous" bacterial peritonitis (SBP). We report another patient with P. multocida bacteremia and SBP and suggest that there may be more than a chance association between cirrhotic liver disease and this unusual organism which rarely causes sepsis in man.

Isolation of transducing particles of phi-80 bacteriophage that carry different regions of the Escherichia coli genome

It has been possible to mate two strains harboring F-prime (F') factors and to isolate from such matings rare recombinants that behave as though the two episomes had fused. Thus, two genes not previously linked may be brought into close proximity. An F' factor carrying the attachment site for varphi80 was fused with one carrying the met-ppc-arg region of the chromosome. Lysogenization of such a strain, followed by induction, led to the isolation of varphi80arg(+) and varphi80met(+) transducing phages. This technique may be utilized as a general method for joining diverse bacterial genes to the genome of phage varphi80.