The Effect of Monomers and of Micellar and Vesicular Forms of Non-ionic Surfactants (Solulan C24 and Solulan 16) on Caco-2 Cell Monolayers

Measurements of transepithelial electrical resistance (TEER), the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) test and monitoring of poly(ethylene glycol) (PEG) transport have been used to study the effects of the non-ionic surfactants Solulan C24 and Solulan 16, either free in solution or as an integral part of niosome bi-layers, on intestinal epithelial cells from man (Caco-2 cell monolayers). The effects on epithelial integrity and on the transport of the hydrophilic drug metformin depend on the concentration of the surfactants. At concentrations above 1% the effect on TEER of the surfactant in niosomal form and free in solution were equivalent whereas cell viability was preserved to a higher concentration of Solulans when the Solulans were present in the niosomal form. It was concluded that the toxic effect of niosomes arises from free surfactant present in the niosome suspension.     

Effects of haloperidol and amisulpride on motor and cognitive skill learning in healthy volunteers

Buprenorphine is a mu opioid partial agonist currently used as an analgesic, and being developed for the treatment of opioid dependence. The purpose of this study was to determine the abuse liability of parenteral buprenorphine in volunteers maintained on daily sublingual (SL) buprenorphine (8 mg). In a residential laboratory, eight volunteers underwent pharmacologic challenges two times per week. Medication challenges were 16 h after the daily dose of buprenorphine, and consisted of double-blind IM injections of buprenorphine (4, 8, 16 mg), the prototypic mu opioid agonist hydromorphone (9 and 18 mg), or saline. Assessments consisted of physiologic monitoring, subjects’ self-reports, and a trained observer’s ratings of drug effects, and were collected for 0.5 h before and 2.0 h following injection. Supplemental doses of IM buprenorphine produced opioid agonist-like effects, indicating some abuse potential of parenteral buprenorphine in buprenorphine-maintained patients. There was incomplete cross-tolerance to the effects of hydromorphone, suggesting that higher maintenance doses of buprenorphine may be needed to maximize clinical efficacy. However, there was a lack of graded dose-effects for hydromorphone, suggesting that buprenorphine’s combination of partial agonist effects and high affinity for opioid receptors may limit the magnitude of effects of supplemental full agonists. Finally, participants tolerated cumulative doses of maintenance buprenorphine plus challenge buprenorphine without adverse effects, suggesting higher doses of buprenorphine can be safely administered to opioid dependent patients. Received: 22 February 1996/Final version: 23 August 1996     

In vivo (31)P magnetic resonance spectroscopy and morphometric analysis of the perfused vascular architecture of human glioma xenografts in nude mice.

The relationship between the bioenergetic status of human glioma xenografts in nude mice and morphometric parameters of the perfused vascular architecture was studied using (31)P magnetic resonance spectroscopy (MRS), fluorescence microscopy and two-dimensional digital image analysis. Two tumour lines with a different vascular architecture were used for this study. Intervascular distances and non-perfused area fractions varied greatly between tumours of the same line and tumours of different lines. The inorganic phosphate-nucleoside triphosphate (P(i)/NTP) ratio increased rapidly as mean intervascular distances increased from 100 microm to 300 microm. Two morphometric parameters - the percentage of intervascular distances larger than 200 microm (ivd200) and the non-perfused area fraction at a distance larger than 100 microm from a nearest perfused vessel (area100), - were deduced from these experiments and related to the P(i)/NTP ratio of the whole tumour. It is assumed that an aerobic to anaerobic transition influences the bioenergetic status, i.e. the P(i)/NTP ratio increased linearly with the percentage of ivd200 and the area100.     

Sensitization to Zygophyllum fabago pollen. A clinical and immunologic study

Zygophyllum fahago is a herbaceous plant found widely in the Mediterranean area. There are no previous reports of its allergenicity. An aerobiologic and clinical survey was conducted in Murcia, southern Spain, to determine the quantity of airborne pollen and establish the possible role of this pollen as a cause of allergic symptoms. With a Hirst volumetric trap, we determined the atmospheric concentrations of this pollen in 1993, 1994,1995, and 1996. Of 1180 patients tested, 181 (15,34%) had a positive skin test. To determine its allergenicity, we divided 47 patients into three groups: in group 1, all the patients had symptoms of rhinoconjunctivitis plus asthma; in groups 2 and 3, rhinoconjunctivitis. In group 1, we performed a bronchial provocation test (BPT): in groups 2 and 3, we performed nasal provocation (NPT) and conjunctival provocation (CPT) tests, respectively, SDS-PAGE was used to characterize the antigenic fractions and RAST inhibition to determine cross-reactivity with other pollens. The pollen dispersion period is from May to September (445 grains/m³), BPT was positive in 13 of 15 patients, NPT in 14 of 16 patients, and CPT in 13 of 16 patients. RAST inhibition revealed cross-reactivity with Mercurialis, Ricinus, Olea. and Betula. SDS-PAGE identified 25 IgE antibody-binding components, five of which (60, 65, 41, 38, and 15.5/14,7 kDa) were recognized by 40% of the sera. By SDS-PAGE immunoblotting with sunflower antiprofilin rabbit serum and affinity chromatography we established that the Z. fahago extract has profilin. This study shows that this pollen becomes airborne and elicits an IgE response which triggers respiratory symptoms in allergic subjects.     

Hemolytic properties and riboflavin synthesis of Helicobacter pylori: cloning and functional characterization of the ribA gene encoding GTP-cyclohydrolase II that confers hemolytic activity to Escherichia coli

Various strains of Helicobacter pylori were able to lyse erythrocytes from sheep, horse, and human when grown on blood agar. The hemolysis did not depend on the production of the vacuolating cytotoxin VacA as demonstrated by the hemolytic behavior of an isogenic vacA-negative mutant strain. The hemolytic activity could be detected in cell-free supernatants and was not regulated by iron. To isolate genes coding for proteins involved in the destruction of erythrocytes, a plasmid-based DNA library was screened for expression of lytic activity on blood agar. This approach revealed that the H. pylori ribA gene confers hemolytic properties to Escherichia coli. The ribA gene encodes the enzyme GTP-cyclohydrolase II [EC 3.5.4.25] that catalyzes the initial step in the synthesis of riboflavin. The predicted amino acid sequence of the H. pylori RibA protein showed a high degree of similarity to equivalent enzymes from microorganisms and from plants. The single gene on a plasmid restored riboflavin synthesis in a ribA mutant of E. coli and induced hemolytic activity. Furthermore, ribA overexpression was associated with the production of a fluorescent yellow molecule that was not identical with riboflavin. Hemolysis was also seen for the ribA gene from E. coli, indicating that this feature was not specific for the H. pylori gene. The presence of ribA in various H. pylori strains was confirmed by Southern blot hybridization and by polymerase chain reaction with specific primers. This analysis revealed that microdiversity exists within the DNA region upstream from ribA, which was further confirmed by nucleotide sequence analysis. Received: 25 July 1997     

Adult rat seminiferous tubules secrete a fraction greater than 30 kDa to regulate spermatogenesis

The present study was designed to examine the effects of a >30kDa fraction of medium conditioned for 2 days by adult rat seminiferoustubules on inhibin secretion by cultured tubules, and on spermatogenesisand fertility of male rats. Inhibin secretion was assayed byadding the >30 kDa fraction to 5 cm segments of adult ratseminiferous tubules and measuring inhibin by radioimmunoassayat 2 day intervals. Fertility was assayed by injecting malerats daily for up to 45 days with the >30 kDa fraction andthen mating them with a proestrus female, or by injecting for15 days and mating them with two female rats. The assay usedto evaluate the in-vivo effect of the >30 kDa fraction onthe testis involved an assessment of frequencies of seminiferoustubule stages scored by transillumination on intact tubules.The addition of the >30 kDa fraction to the adult rat seminiferoustubules cultured for 2 days resulted in an inhibition of inhibinsecretion into the medium. This effect was reversed when thefraction was removed and changed with fresh medium and culturedfor a further 4 days. The >30 kDa fraction administered i.p.to adult male rats resulted in a low fertilization rate comparedto control rats (67%) (P < 0.05). The assessment of frequenciesof seminiferous tubule stages scored by transillumination showedan increased frequency of stage VI and decreased frequency ofstages VII and VIII after treatment. The results of the presentstudy provide additional evidence that local regulation of Sertolicell function is mediated by a >30 kDa component or componentssecreted by adult seminiferous tubules which could arrest spermatogenesis.