Combining electrokinetic transport and bioremediation for enhanced removal of crude oil from contaminated marine sediments: Results of a long-term, mesocosm-scale experiment.

Marine sediments represent an important sink of harmful petroleum hydrocarbons after an accidental oil spill. Electrobioremediation techniques, which combine electrokinetic transport and biodegradation processes, represent an emerging technological platform for a sustainable remediation of contaminated sediments. Here, we describe the results of a long-term mesocosm-scale electrobioremediation experiment for the treatment of marine sediments contaminated by crude oil. A dimensionally stable anode and a stainless-steel mesh cathode were employed to drive seawater electrolysis at a fixed current density of 11 A/m2. This approach allowed establishing conditions conducive to contaminants biodegradation, as confirmed by the enrichment of Alcanivorax borkumensis cells harboring the alkB-gene and other aerobic hydrocarbonoclastic bacteria. Oil chemistry analyses indicated that aromatic hydrocarbons were primarily removed from the sediment via electroosmosis and low molecular weight alkanes (nC6 to nC10) via biodegradation.

Presence of Clostridium difficile in pig faecal samples and wild animal species associated with pig farms.

AIMS: To determine the presence of Clostridium difficile on fattening pig farms in north-eastern Spain. METHODS AND RESULTS: Twenty-seven farms were sampled. Pools of pig faecal samples (n = 210), samples of intestinal content from common farm pest species (n = 95) and environment-related samples (n = 93) were collected. Isolates were tested for toxin genes of C. difficile, and typed by PCR-ribotyping and toxinotyping. The minimal inhibitory concentrations of six antimicrobial agents were determined using Etest. Thirty-four isolates were obtained from 12 farms, and 30 (88·2%) had toxin genes. Seven ribotypes were identified. Ribotype 078 and its variant 126 were predominant (52·9%). The same ribotypes were isolated from different animal species on the same farm. None of the isolates were resistant to metronidazole or vancomycin. CONCLUSIONS: Clostridium difficile was common within the pig farm environment. Most of the positive samples came from pest species or were pest-related environmental samples. SIGNIFICANCE AND IMPACT OF THE STUDY: Pest species were colonized with toxigenic and antimicrobial-resistant C. difficile strains of the same ribotypes that are found in humans and pigs. Rodents and pigeons may transmit toxigenic and antimicrobial-resistant C. difficile strains that are of the same ribotypes as those occuring in humans.

Pivotal Role of Iron in the Regulation of Cyanobacterial Electron Transport.

Iron-containing metalloproteins are the main cornerstones for efficient electron transport in biological systems. The abundance and diversity of iron-dependent proteins in cyanobacteria makes those organisms highly dependent of this micronutrient. To cope with iron imbalance, cyanobacteria have developed a survey of adaptation strategies that are strongly related to the regulation of photosynthesis, nitrogen metabolism and other central electron transfer pathways. Furthermore, either in its ferrous form or as a component of the haem group, iron plays a crucial role as regulatory signalling molecule that directly or indirectly modulates the composition and efficiency of cyanobacterial redox reactions. We present here the major mechanism used by cyanobacteria to couple iron homeostasis to the regulation of electron transport, making special emphasis in processes specific in those organisms.

Incidence of complications after transrectal ultrasonography-guided biopsy of the prostate in a local tertiary institution.

INTRODUCTION: This study aimed to evaluate the risk of complications for patients who received periprosthetic nerve block (PPNB) with one percent lignocaine before transrectal ultrasonography (TRUS) biopsy of the prostate. METHODS: From 2008 to 2009, data on 526 consecutive patients who underwent prostate biopsy was prospectively recorded and analysed. 475 (90.3 percent) patients received PPNB with 10 ml of one percent lignocaine (Group 1), which was carried out under TRUS-guidance and prior to biopsy. 51 (9.7 percent) patients received diclofenac (100 mg) intramuscular injections or no analgesia (Group 2). Complications were defined as any adverse effects after biopsy. Serious complications were defined as those requiring hospitalisation or invasive/operative procedures for treatment. RESULTS: At baseline, both groups were comparable. The mean prostate-specific antigen level in Group 1 was higher than that in Group 2 (48.6 +/- 13.8 versus 19.0 +/- 4.3 ng/ml; p-value is 0.04). There was no perioperative mortality. Post-procedural complications were reported in 23.4 percent (n is 111) of patients in Group 1 and 25.5 percent (n is 13) in Group 2 (p-value is 0.27). Serious complications were reported in 2.5 percent (n is 12) and 7.1 percent (n is 3) of Group 1 and 2 patients (p-value is 0.10), respectively. Both univariable and logistic regression revealed age below 65 years and pre-procedure complaints of lower urinary tract symptoms as independent predictors for complications (p-values are 0.02 and 0.006, respectively). CONCLUSION: PPNB with one percent lignocaine is a safe analgesic procedure to perform in patients undergoing TRUS biopsy.

Effects of melatonin implants during non-breeding season on sperm motility and reproductive parameters in Rasa Aragonesa rams.

The effect of melatonin implants administered during non-breeding season in Rasa Aragonesa rams on sperm motility parameters and other reproductive traits was assessed. In a first experiment, two Rasa Aragonesa rams were implanted (with melatonin group M), remaining other two males as control group (C). Semen of each group was collected from 1 May to 23 June, twice or three times a week, and motility parameters were assessed using a computer-assisted sperm analysis system. Melatonin increased the percentage of progressive motile spermatozoa, particularly during 46-75 days after melatonin implantation (p < 0.01). In experiment 2, M and C in vitro fertilization ability had been determined by zona-pellucida binding assays, using spermatozoa from experiment 1, obtained 60-70 days after melatonin was implanted. A significantly higher number of spermatozoa attached per oocyte was observed in frozen-thawed immature ovine oocytes incubated with sperm from M animals than in those incubated with sperm from the C group (p < 0.01). Finally, a field assay (experiment 3) was performed. In this case, five Rasa Aragonesa rams were implanted with melatonin and three remained as control group. Sperm doses from those animals were used for artificial insemination of 2608 Rasa Aragonesa ewes from 39 different farms at non-breeding season. Fertility, litter size and fecundity were studied. Semen from melatonin implanted rams seemed to increase both fertility and fecundity in ewes inseminated with spermatozoa obtained 46-60 days after implantation (p < 0.1). Thus, melatonin treatment in rams during non-breeding season modifies sperm motility parameters and seems to improve the fertilization parameters obtained.

Optimization of intracellular microcystin-LR extraction for its analysis by protein phosphatase inhibition assay.

Microcystins are toxins produced by some strains of cyanobacteria. Several methods have been developed to allow the quantification of microcystins, which are mainly endotoxins. Among those methods, the protein phosphatase inhibition assay is a good candidate as a screening method because of its sensitivity, simplicity and specificity. In this work a method for intracellular microcystin extraction in field water samples and lab cyanobacterial cultures prior to their analysis by protein phosphatase inhibition assay has been optimized. Microcystin-LR and Microcystis aeruginosa PCC 7806 were used as reference microcystin and strain, respectively, in order to optimize the protocol. The protocol consists on filtering the sample through a nylon filter of 0.8 microm, filter extraction with methanol 80% 0.1% trifluoroacetic acid (TFA) 0.1% tween 20, extract centrifugation and supernatant dilution (1/20). The establishment of an extraction protocol was carried out determining the extraction volume, time of extraction and number of extractions. The advantages of the method developed in this work are basically its simplicity and avoiding the use of specific and expensive equipment.

Exploring the interaction of microcystin-LR with proteins and DNA.

The physiological role of microcystin-LR is still under discussion, and since binding of microcystin-LR to proteins different from their main cellular targets was described, we have performed experiments in order to explore this interaction. A non-specific interaction of microcystin-LR with a variety of soluble proteins in vitro is disrupted when using organic solvents such as methanol. The isoelectric point of proteins is not affected by their interaction with microcystin-LR, even though the presence of microcystin-LR alters the pool of peptides obtained by tryptic digestions. Under the conditions tested, microcystin-LR does not exhibit affinity for DNA. Although it is unlikely that the non-specific binding of microcystin-LR to proteins has a physiological meaning, one must be aware of the fact that determinations of the toxin extracted from any biological sample may be affected by the presence of proteins in the extracts. Consequently, we strongly recommend use organic solvents and to lyophilise the tissue samples to guarantee the accessibility of these organic solvents to microcystin-LR when performing experiments with tissue or cell extracts.

[Damage to retinal vasculature]. / Les dommages vasculaires rétiniens.

The use of interferon increased these last years. Cotton wool-spots, retinal hemorrhages, and microaneurysms are common manifestations of interferon retinopathy. The frequency of this retinopathy is underestimated as it is often asymptomatic. Screening and a multidisciplinary approach are therefore recommended.

Prediction of fertility by centrifugal countercurrent distribution (CCCD) analysis: correlation between viability and heterogeneity of ram semen and field fertility.

The prediction of the fertilizing ability of a sire or a given insemination dose is a primary aim in the field of artificial insemination. Centrifugal countercurrent distribution analysis (CCCD) was used to determine the relationship between some sperm parameters and the in vivo fertility rate obtained with the same sample after cervical artificial insemination. A total of 522 ewes from 26 different farms was inseminated with 53 ejaculates obtained from 25 mature Rasa aragonesa rams. Semen was diluted to 1.6 x 10(9) cells ml-1 and doses of 0.25 ml were prepared and kept at 15 degrees C until used for insemination. The same ejaculates were used for analysis of standard semen parameters and CCCD analysis. Sperm motility, concentration and viability were determined before and after CCCD. Post-CCCD parameters were derived from the analysis of the profile obtained after CCCD. The recovered viability showed the highest correlation with fertility, especially in the central chambers (V2), r = 0.415, P < 0.005). The ejaculate heterogeneity also showed a positive correlation with field fertility (r = 0.23), with a tendency towards significance (P < 0.1). The mean fertility value of all ejaculates used in this study was 46.75%, ranging from 12.5% to 75.0%. Ejaculates were classified into two categories according to their fertility: higher and lower than the mean value. Only the viability recovered in the central chambers (V2) was a parameter with a predictive capacity to discriminate between the two groups (P < 0.05). A predictive equation for field fertility with a correlation coefficient r = 0.488 and a very high level of significance (P < 0.005) was deduced by multiple analysis: PF = 6.02 + 0.069V2 + 0.315H (where PF is predictive fertility, V2 is the recovered viability in the CCCD profile central chambers and H is heterogeneity).

Effects of gamma-linolenic acid and oleic acid on paclitaxel cytotoxicity in human breast cancer cells.

It has been suggested that dietary interventions may improve the effectiveness of cancer chemotherapy. We have examined the combined in vitro cytotoxicity of paclitaxel and the fatty acids gamma-linolenic acid (GLA, 18:3n-6) and oleic acid (OA, 18:1n-9) in human breast carcinoma MDA-MB-231 cells. The effect of fatty acids on paclitaxel chemosensitivity was determined by comparing IC(50) and IC(70) (50 and 70% inhibitory concentrations, respectively) obtained when the cells were exposed to IC(50) and IC(70) levels of paclitaxel alone and fatty acids were supplemented either before or during the exposure to paclitaxel. The 3-4,5-dimethylthiazol-2-yl-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to determine cell growth inhibition. GLA by itself showed antiproliferative effects, and a possible GLA-paclitaxel interaction at the cellular level was assessed by the isobologram and the combination-index (CI) methods. Isobole analysis at the isoeffect levels of 50 and 70% revealed that drug interaction was predominantly synergistic when GLA and paclitaxel were added concurrently for 24 h to the cell cultures. Interaction assessment using the median-effect principle and the combination-index (CI) method showed that exposure of MDA-MB-231 cells to an equimolar combination of concurrent GLA plus paclitaxel for 24 h resulted in a moderate synergism at all effect levels, consistent with the results of the isobologram analysis. When exposure to GLA (24 h) was followed sequentially by paclitaxel (24 h) only an additive effect was observed. The GLA-mediated increase in paclitaxel chemosensitivity was only partially abolished by Vitamin E, a lipid peroxidation inhibitor, suggesting a limited influence of the oxidative status of GLA in achieving potentiation of paclitaxel toxicity. When OA (a non-peroxidisable fatty acid) was combined with paclitaxel, an enhancement of chemosensitivity was found when OA was used concurrently with paclitaxel, although less markedly than with GLA. Pretreatment of MDA-MB-231 cells with OA for 24 h prior to a 24 h paclitaxel exposure produced greater enhancement of paclitaxel sensitivity at high OA concentrations than the concurrent exposure to OA and paclitaxel. The OA-induced sensitisation to paclitaxel was not due to the cytoxicity of the fatty acid itself. When these observations were extended to three additional breast carcinoma cell lines (SK-Br3, T47D and MCF-7), simultaneous exposure to GLA and paclitaxel also resulted in synergism. GLA preincubation followed by paclitaxel resulted in additivity for all cell lines. Simultaneous exposure to paclitaxel and OA enhanced paclitaxel cytotoxicity in T47D and MCF-7 cells, but not in SK-Br3 cells, whereas preincubation with OA failed to increase paclitaxel effectiveness in all three cell lines. For comparison, the effects of other fatty acids on paclitaxel chemosensitivity were examined: GLA was the most potent at enhancing paclitaxel cytotoxicity, followed by alpha-linolenic acid (ALA; 18:3n.3), eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), whereas linoleic acid (LA; 18:2n-6) did not increase paclitaxel toxicity. These findings provide experimental support for the use of fatty acids as modulators of tumour cell chemosensitivity in paclitaxel-based therapy.

Copago y accesibilidad a los servicios sanitarios / Co-payment and access to health services

No disponible

[Perceptions regarding leprosy and resulting handicaps prior to diagnosis in Recife, Brazil]. / Percepción de la lepra y las discapacidades antes del diagnóstico en Recife, Brasil.

This article reports on a case-control study conducted in Recife, Brazil, between November 1993 and July 1994, to determine how leprosy patients' perceptions and notions influence disease management and use of health services. The sample was composed of 183 residents of Recife between the ages of 20 and 70 years who sought diagnostic services in the dermatology clinics of two referral centers situated in the third, fourth, and sixth political and administrative regions. Sixty-four patients having handicaps or their precursor lesions were classified as cases; the remaining 119 were used as controls. All were diagnosed during the study period. For the analysis, adjustments were made for sex, age, schooling, and a previous history of Hansen's disease among patients. The study revealed the simultaneous presence of two types of "invisibility" of the disease in an area where endemicity is increasing: 1) for patients in both groups, the low frequency of spontaneous explanatory models related to the illness, even in the presence of disease, and 2) for health professionals, the limitations of detection methods. Since such deficiencies affect decisions bearing on individual and collective disease management, they are a risk factor in and of themselves and stand in the way of eliminating leprosy as a public health problem.

Prevention by the 5-HT3 receptor antagonist, ondansetron, of morphine-dependence and tolerance in the rat.

1. The effect of ondansetron, a selective 5-hydroxytryptamine3 (5-HT3) receptor antagonist, was studied in morphine-addicted rats. Morphine-dependence and tolerance, induced by drinking increasing concentrations of morphine sulphate in 5% sucrose solution for 3 weeks, were demonstrated by the naloxone-precipitated withdrawal syndrome and tail flick response to a thermal noxious stimulus (water at 50 degrees C), respectively. 2. Morphine-dependence, assessed by naloxone precipitated withdrawal, was undetectable by the 6th day, when the animals drank only tap water for 7 days after the 3-week induction period. 3. When detoxified rats were offered sucrose and morphine solutions for 10 days, the recurrence of opiate solution preference with relapse to dependence and tolerance was observed. 4. Giving ondansetron (0.1 or 1 microgram kg-1; i.p.; twice daily) on the 14th day of, or 7 days prior to, the 3-week induction period reduced dependence and tolerance seen during the 3-week morphine induction and the 10-day drinking preference periods. 5. 5-Hydroxytryptamine2 (5-HT2) receptor antagonism by cyproheptadine (100 or 250 micrograms kg-1; i.p.; twice daily) did not influence morphine-dependence and tolerance. 6. These findings suggest that ondansetron may be useful for treating opiate addiction and lowering the recidivism rate.

A phase I/II study of paclitaxel plus cisplatin as first-line therapy for head and neck cancers: preliminary results.

Improved outcomes among patients with head and neck carcinomas require investigations of new drugs for induction therapy. Preliminary results of an Eastern Cooperative Oncology Group study of single-agent paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) reported a 37% response rate in patients with head and neck cancer, and the paclitaxel/cisplatin combination has been used successfully and has significantly improved median response duration in ovarian cancer patients. We initiated a phase I/II trial to determine the response and toxicity of escalating paclitaxel doses combined with fixed-dose cisplatin with granulocyte colony-stimulating factor support in patients with untreated locally advanced inoperable head and neck carcinoma. To date, 23 men with a median age of 50 years and good performance status have entered the trial. Primary tumor sites were oropharynx, 10 patients; hypopharynx, four; larynx, two; oral cavity, three; unknown primary, two; and nasal cavity and parotid gland, one each. Of 20 patients evaluable for toxicity, four had stage III and 16 had stage IV disease. Treatment, given every 21 days for a maximum of three cycles, consisted of paclitaxel by 3-hour infusion followed the next day by a fixed dose of cisplatin (75 mg/m2). The dose levels incorporate escalating paclitaxel doses, and intrapatient escalations within a given dose level are permitted if toxicity permits. At the time of this writing, dose level 4 (260, 270, and 280 mg/m2) is being evaluated; three patients from this level are evaluable. With paclitaxel doses of 200 mg/m2 and higher, granulocyte colony-stimulating factor 5 micrograms/kg/d is given (days 4 through 12). Of 18 patients evaluable for response, seven (39%) achieved a complete response and six (33%) achieved a partial response. Three patients had no change and disease progressed in two. The overall response rate is 72%. Eleven responding patients had subsequent surgery/radiotherapy or radical radiotherapy. Two pathologic complete responses were observed in patients who had achieved clinical complete responses. Alopecia, paresthesias, and arthralgias/myalgias have occurred frequently, but with one exception (a grade 3 myalgia) they have been grade 1 or 2. No dose-limiting hematologic toxicity has been seen. Paclitaxel/cisplatin is an effective first-line regimen for locoregionally advanced head and neck cancer and continued study is warranted. Results thus far suggest no dose-response effect for paclitaxel doses above 200 mg/m2.

["All in one" parenteral nutrition: is it that safe?]. / Nutrición parenteral "todo en uno": es tan segura?

The use of "all in one" admixtures is supported by an extensive number of studies and by many years of experience. However, we detected stability problems in some mixtures whose stability was previously reported. We made modifications in one of these mixtures [composed of 1.000 ml Freamine 8.5%, 100 ml 10% dextrose, 500 ml water, 500 ml Intralipid 20%, 75 ml electrolyte solution (Na 75 mEq, K 60 mEq, Ca 15 mEg, Mg 15 mEq, Cl 90 mEq, acetate 75 mEq)] in order to see how the different components affect the emulsion stability. All the admixtures were visually inspected after storage during 24 hour at room temperature. It was observed that admixtures with low glucose concentration, high electrolyte levels and high volume were less stable than admixtures containing high glucose, low electrolyte and low volume. Amino acid concentration did not increased the stability as expected. MCT/LCT emulsions were more stable than LCT emulsions. More studies are needed to explain the stability problems of these TPN solutions.

5-HT3 antagonists reduce morphine self-administration in rats.

1. The effects of the 5-HT3 receptor antagonists, ondansetron and tropisetron, on morphine consumption were studied in naive and morphine-dependent rats. 2. The administration of ondansetron (1 microgram kg-1, i.p. twice daily) 7 days prior to, and during a 21-day period of, morphine availability (increasing concentration from 0.1 to 0.4 mg ml-1) in 5% sucrose solution reduced opiate intake from the 9th day of morphine treatment. 3. The administration of ondansetron (0.1 microgram kg-1, i.p. twice daily) or tropisetron (0.1 microgram kg-1, i.p. twice daily) on the 14th day of the 21-day period of morphine treatment failed to reduce opiate consumption. Administration of the larger doses of tropisetron (1 microgram kg-1) or ondansetron (1 microgram kg-1) reduced morphine consumption. 4. After receiving 21 days of treatment with morphine alone or with the ondansetron or tropisetron regimens identified above, the sucrose solutions were substituted with tap water for 7 days. These detoxified rats were then allowed a free choice of sucrose or morphine for 10 days. Animals that had received concomitant treatment with ondansetron or tropisetron showed reduced morphine intake when compared with the controls treated with morphine only or with vehicle-treated controls. 5. The administration of cyproheptadine (100 or 250 micrograms kg-1, i.p. twice daily) on the 14th day of 21-day morphine treatment failed to modify morphine intake and also failed to influence the subsequent intake of the opiate in the free choice situation. 6. It is concluded that ondasetron and tropisetron can reduce morphine intake in both naive and morphine-dependent rats.

Effect of ethanol intake on lipoprotein lipase activity in rat heart.

We examined the effects of the in vivo administration of ethanol on lipolytic activities assayed in rat post-heparin heart effluents, that hydrolyse tri-, di- and monoacylglycerol. Properties of triacylglycerol lipase (TAGL) are typical of lipoprotein lipase (LPL) whereas diacylglycerol (DAGL) and monoacylglycerol (MAGL) lipase activities hydrolyse sequentially the products of LPL action. After 15 days of ethanol intake, TAGL, DAGL and MAGL activities in post-heparin heart effluents were decreased respectively by 25, 38 and 22%; after 30 days, the decreases amounted to 81, 79 and 71%. After 30 days, but not after 15 days, ethanol increased the levels of triacylglycerol in plasma. Ethanol intake concomitantly decreased TAGL and DAGL activities in post-heparin effluents and in heart tissue extracts, whereas MAGL activity was decreased only in the latter extracts. We conclude that ethanol intake causes a marked impairment in heart LPL and in two closely-related heparin-releasable activities, seemingly by altering the production of a catalytically active enzyme. A distinct heparin-unreleasable MAGL appears to exist in heart, that could be ethanol-insensitive. Overall, the results suggest that a LPL-related alteration in fatty acid supply could contribute to the toxicity of ethanol in heart.

Sensitivity and specificity of transcranial Doppler ultrasonography in the diagnosis of vasospasm following subarachnoid hemorrhage.

Vasospasm is the leading cause of death and disability in patients with aneurysmal subarachnoid hemorrhage (SAH). Transcranial Doppler ultrasonography (TCD) can detect the arterial narrowing noninvasively, but the sensitivity and specificity of this technique have not been reported in a population of patients with a high frequency of angiographic vasospasm. In this study, 34 consecutive patients with SAH undergoing angiography during the period of risk for vasospasm had technically adequate TCD examinations within 24 hours of the angiogram. Using a mean flow velocity of 120 cm/sec and above as indicative of vasospasm, TCD correctly detected angiographic vasospasm in 17 patients; there were no false positives. It correctly determined that 5 patients did not have vasospasm, whereas there were 12 false negatives. False negatives were frequently due to angiographic vasospasm involving vessels not assessable by TCD. The correlation between mean flow velocity and the angiographic residual lumen diameter of the middle cerebral artery was statistically significant. These data suggest that TCD is a highly specific (100%), but less sensitive (58.6%) test for the detection of angiographic vasospasm following SAH. Confirmatory angiography may be avoided if the TCD study is positive, but additional studies may be necessary if the clinical picture is suspicious and the TCD study is negative.

The protective effects of sulphasalazine against ethanol-induced gastric damage in rats.

1 The inhibitory action of sulphasalazine on ethanol-induced gastric damage was studied in rats. 2 Sulphasalazine (62.5 or 125 mg kg-1, s.c.) did not affect basal gastric acid secretion but increased pepsin output. 3 Ethanol (40% v/v, 10 ml kg-1, p.o.) produced severe gastric glandular mucosal damage and lessened the stomach emptying rate of resin pellets, but it increased the levels of prostaglandin E2 (PGE2)-like activity in the glandular mucosa. 4 Sulphasalazine markedly prevented ethanol-induced damage and significantly elevated gastric wall mucus levels both in basal conditions and in the presence of ethanol. 5 Sulphasalazine caused a small insignificant increase in mucosal PGE2 levels in both control and ethanol-treated rats. The drug significantly increased mucosal PGE2 levels in indomethacin-treated animals, but did not prevent indomethacin-induced mucosal damage. 6 Sulphapyridine but not 5-aminosalicylic acid, constituents of sulphasalazine, showed a similar antilesion action to the parent drug, and prevented gastric wall mucus depletion in ethanol-treated animals. 7 This study elucidates the protective effects of sulphasalazine against ethanol-induced gastric lesions. The antagonistic action appears to be mediated, at least partly, through the preservation of gastric wall mucus by sulphapyridine.