Recent studies in a cultured model of the intestinal epithelium (HT-29cl.19A) have shown that somatostatin-14 (SS-14) inhibits the Cl- secretory process by acting at multiple G protein-dependent ...sites. These actions may underlie the antidiarrheal properties of SS peptides. This study has investigated the expression of specific SS receptor subtypes (SSTR) in HT-29cl.19A and examined their role in mediating SS antisecretory actions. Two predominant SSTR, SSTR1 and SSTR2, were identified by reverse transcriptase-polymerase chain reaction (RT-PCR) of mRNA from polarized HT-29cl.19A monolayers. Receptor binding studies showed evidence of two distinct populations of binding sites consistent with the known properties of SSTR1 and SSTR2. The role of SSTR in inhibition of secretion was investigated by comparing the effectiveness of native and synthetic SS peptides on adenosine 3',5'-cyclic monophosphate (cAMP)-dependent Cl- secretion. Secretion stimulated by the receptor-mediated agonist prostaglandin E2 (PGE2) was inhibited > 70% by SS-14 with a 50% effective concentration (EC50) of 32 nM. In contrast, SMS-201-995 (SMS) and RC-160 exhibited little or no antisecretory activity (maximum inhibition of 15 +/- 1.9 and 2.8 +/- 1.9%, respectively, at 100 microM; EC50 > 1.5 microM). Similar effects on PGE2-stimulated cAMP accumulation were also observed. SS-14, but not SMS, also inhibited secretion stimulated by dibutyryl cAMP, which acts independently of changes in cellular cAMP. Pretreatment with pertussis toxin reversed the antisecretory effects of SS peptides.
Summary points Genetic screening for hereditary haemochromatosis is now a reality New treatments for Barrett's oesophagus can remove gastric and intestinal metaplasia Helicobacter pylori can be ...eradicated effectively in 1 week by a regimen of drugs given twice daily Progress is being made in developing an oral vaccine against H pylori Endoscopic screening reduces mortality from colon cancer, but issues of social cost need further evaluation Although the cause of Crohn's disease remains elusive, response to some antibiotic regimens suggests an infective link involving intestinal bacteria in susceptible people A 20 year search The increased frequency of the HLA-A3 allele in patients with hereditary haemochromatosis was the first indication that the gene for this disorder might be situated near the major histocompatibility complex on chromosome 6p. Viruses have come under scrutiny, and recent attention has been focused on the measles virus as a possible pathogenetic agent. 29 However, studies using validated, sensitive molecular biology methods have found no evidence of measles genomic material in Crohn's disease tissues. 30 Crohn's disease and Mycobacterium paratuberculosis The close resemblance to tuberculosis in humans and Johne's disease in sheep and goats is striking, but reproducible acid fast bacilli have not been found in affected human tissues. 31 Many thorough clinical trials of antimycobacterial treatment have failed to show any effect. 32 The relevance of detecting mycobacterial fragments in Crohn's tissues using molecular biology techniques such as the polymer chain reaction is controversial.
An incidentally discovered infestation with the nematode Syphacia muris of cecum and colon in spontaneously hypertensive (SHR) and normotensive control (WKY) rats was investigated over a two-year ...period. Infestation rates in WKY were higher than in SHR, while clinical signs as well as histological changes of colonic tissues were absent in both strains. In vivo net water absorption (microliter/hr/cm2) in control worm-free SHR turned into secretion in infested rats, ie, from 74.2 +/- 23.2 to -7.5 +/- 35.0 (P less than 0.001); this corresponded with a decrease in net absorption (mumol/hr/cm2) of Na from 18.5 +/- 2.4 to 9.3 +/- 4.3 (P less than 0.001) and of Cl from 14.0 +/- 3.2 to 3.2 +/- 5.7 (P less than 0.001). In WKY, net water absorption decreased from 112.2 +/- 23.2 to 48.0 +/- 25.1 (P less than 0.001) and Na and Cl absorption from 22.3 +/- 3.1 to 16.0 +/- 4.2 (P less than 0.005) and from 19.4 +/- 2.7 to 10.9 +/- 4.7 (P less than 0.005), respectively. Antihelminthic treatment with 0.007% pyrvinium pamoate in the ration (four weeks on, six months off) eradicated Syphacia muris in both rat strains. Body weight gain of young rats on normal and pyrvinium pamoate-substituted diet studied over 18 months was similar, indicating a good tolerance of the treatment. It is concluded that results obtained during comparative intestinal transport studies between SHR and WKY may not only be impaired but also significantly distorted by Syphacia muris infestation as SHR appear to be more susceptible to effects induced by this common parasite than WKY.
Background: Helicobacter pylori seroprevalence increases with age in adult life but spontaneous reversion may occur in childhood and adolescence.
Aims: To determine the seroprevalence of H. pylori in ...a longitudinal study of New Zealanders at ages 11 and 21.
Methods: Serum from members of the Dunedin Multidisciplinary Health and Development Study (DMHDS) at age 11 (n=561; 303 males, 258 females) and 21 (n=785; 413 males, 372 females) was tested for H. pylori antibodies. A large proportion of those tested at age 11 was retested at age 21 (n=465; 262 males, 203 females). Serological status was examined in terms of gender, socioeconomic status (SES) and self‐reported use of antibiotics.
Results: The seroprevalence of H. pylori decreased by 38% from 6.6% (37/561) at age 11 to 4.1% (32/785) at age 21. Seroprevalence at age 11 was not associated with gender or SES. For those tested at both ages, the drop in seroprevalence from 6.7% to 4.1% was statistically significant (t=2.57, ρ<0.01, paired t‐test) and was much greater in females (71%) than males (12%). Of the 31 seropositive individuals at age 11, 17 (six males, 11 females) seroreverted and self‐reported antibiotic use in the year preceeding age 21 was more common in females (eight/11) than males (zero/six). Of die 434 seronegative individuals at age 11, only five (four males, one female) had seroconverted at age 21.
Conclusions: Seroprevalence in the DMHDS declined from age 11 to 21 predominantly in females. The decline involved a greater rate of seroreversion and lower rate of seroconversion in females than males.
In the automotive industry the need for lower manufacturing costs, the use of fewer strategic materials, andthe need for easier, faster, and more environmentally sound coating processes is growing. ...This has led to the examination of a plasma powder spray process used in the application of coatings for surface modification. The present paper examines the use of the plasma powder spray process in coating aluminium-silicon cylinder block bores using a rotating plasma gun capable of producing coatings of reliable microstructure and integrity. Properties and microstructures of the applied coatings are presented and test results show that the necessary bond strength of the coating can be achieved without the use of a bond coat. Surface preparation before coating and surface finishing methods after coating are also discussed. Experience in Europe, Japan, and the USA shows that the plasma powder spray process offers a performance proven and cost effective solution for the coating of cylinder bores.
PDF
