Frequent emergence of resistance in Clostridium difficile during treatment of C. difficile-associated diarrhea with fusidic acid

Samples from patients with Clostridium difficile-associated diarrhea (CDAD) that were randomized to fusidic acid (n = 59) or metronidazole (n = 55) therapy for 7 days were cultured for Clostridium difficile in feces on days 1, 8 to 13, and 35 to 40. Of the patients who were culture positive only before treatment, 77% (36/47) were permanently cured (no treatment failure and no clinical recurrence), compared to 54% (22/41) of those with persistence of C. difficile at one or both follow-ups (P = 0.03). A similar association between bacterial persistence and a worse outcome of therapy was seen in both treatment groups. Resistance to fusidic acid was found in 1 of 88 pretherapy isolates available, plus in at least 1 subsequent isolate from 55% (11/20) of patients who remained culture-positive after fusidic acid therapy. In 10 of these 11 patients, the resistant follow-up isolate(s) belonged to the same PCR ribotype as the susceptible day 1 isolate, confirming frequent emergence of resistance to fusidic acid during treatment. Despite this, 5 of these 11 patients were permanently cured with fusidic acid, relative to 5 of 9 patients with susceptible C. difficile at follow-up (P = 1.0). None of the 36 PCR ribotypes of C. difficile identified was associated with any particular clinical outcome or emergence of fusidic acid resistance. In conclusion, culture positivity for C. difficile was common after both fusidic acid and metronidazole therapy and was associated with treatment failure or recurrence of CDAD. Development of resistance in C. difficile was frequent in patients given fusidic acid, but it was without apparent negative impact on therapeutic efficacy in the actual CDAD episode.     

Patients with coeliac disease have a characteristic gliadin antibody pattern

By use of an immunoblotting technique we have investigated the specificity of circulating IgG antibodies with respect to reactions with the alpha-, beta-, gamma- and omega-fractions of gliadin in patients with coeliac disease and in patients with diarrhoea of other causes. Untreated coeliac patients show a characteristic reactivity against polypeptides in the gamma-fraction, with an Mr of 35 and 45 kilodaltons, but only minor reactivity against the other fractions. One coeliac patient exclusively had antibodies to a 80 kilodalton component. Such a reaction pattern was not observed in other groups of patients with diarrhoea, as they had only weak reactions against the gamma-fraction but a stronger reaction against the other fractions. This might indicate that enterocytes of coeliac patients specifically take up distinct polypeptides of gamma-gliadin and by transcellular transport present them to immunocompetent cells. The results also suggest that there are distinct components of gliadin that provoke symptoms in different coeliac patients, indicating a heterogenecity of the disease. The study might lead to new diagnostic methods and to elucidation of the pathogenetic mechanisms behind coeliac disease.     

Ribosome and free amino acid content in muscle during hemodialysis

Patients (N = 8) with chronic renal failure and uremia treated with hospital hemodialysis were in a pilot study investigated before and after a single hemodialysis session. The extracorporeal dialysis circuit was flushed regularly with saline to avoid clotting and the use of heparin. Percutaneous skeletal muscle biopsies were taken before and after the dialysis to determine the content of free amino acids together with the concentration and size distribution of ribosomes before and after dialysis. After dialysis the alanine concentration in muscle decreased by 20% (P less than 0.05), while all other amino acids were unaffected. The total ribosome concentration per mg of DNA decreased by 31% (P less than 0.01) and the relative proportion of polyribosomes by 7% (P less than 0.05) after the dialysis compared to predialytic values. All individual plasma amino acids decreased during the dialysis procedure except for threonine and arginine, which were unaltered, and leucine and isoleucine, which increased. The decline in ribosome and polyribosome content together with the changes in amino acid levels indicate a low capacity for protein synthesis and increased catabolism in muscle of hemodialyzed patients.     

Fluorine uptake in bovine enamel from various treatment agents

Bovine tooth enamel with a low and uniform fluorine content was used for the study of fluorine uptake by the Micro-Acid-Drop enamel biopsy technique from different treatment agents commonly used in Sweden. The fluorine concentration in the enamel was also measured after an exposure of the treated test surfaces in artificial saliva for 90 minutes. Sodium fluoride 0.2% and 2%, ferric aluminum fluoride solution and Duraphat varnish showed a high uptake of fluorine in the enamel with the highest concentration in the surface layer. Fluor Protector and the toothpastes showed a considerably lower fluorine uptake. After immersion in artificial saliva of the specimens, the concentration of fluorine in the enamel decreased.     

Updates on k13 mutant alleles for artemisinin resistance in Plasmodium falciparum

Background

In the fight against malaria caused by Plasmodium falciparum, the successes achieved by artemisinin were endangered by resistance of the parasites to the drug. Whole genome sequencing approach on artemisinin resistant parasite line discovered k13 gene associated with drug resistance. In vitro and in vivo studies indicated mutations in the k13 gene were linked to the artemisinin resistance.

Tualang honey induces apoptosis and disrupts the mitochondrial membrane potential of human breast and cervical cancer cell lines

Honey is reported to contain various compounds such as phenols, vitamins and antioxidants. The present study investigates the anticancer potential of Tualang honey (Agromas) (TH) in human breast (MCF-7 and MDA-MB-231) and cervical (HeLa) cancer cell lines; as well as in the normal breast epithelial cell line, MCF-10A. The cells were treated with increasing doses of TH (1-10%) for up to 72 h. Increase in lactate dehydrogenase (LDH) leakage from the cell membranes indicates that TH is cytotoxic to all three cancer cells with effective concentrations (EC₅₀) of 2.4-2.8%. TH is however, not cytotoxic to the MCF-10A cells. Reactivity with annexin V fluorescence antibody and propidium iodide as analysed by flow cytometry and fluorescence microscopy shows that apoptosis occurred in these cancer cells. TH also reduced the mitochondrial membrane potential (Δψ_m) in the cancer cell lines after 24 h of treatment. The activation of caspase-3/7 and -9 was observed in all TH-treated cancer cells indicating the involvement of mitochondrial apoptotic pathway. This study shows that TH has significant anticancer activity against human breast and cervical cancer cell lines.     

The pyranoxanthone inophyllin A induces oxidative stress mediated-apoptosis in Jurkat T lymphoblastic leukemia cells

Inophyllin A (INO-A), a pyranoxanthone isolated from the roots of Calophyllum inophyllum represents a new xanthone with potential chemotherapeutic activity. In this study, the molecular mechanism of INO-A-induced cell death was investigated in Jurkat T lymphoblastic leukemia cells. Assessment of phosphatidylserine exposure confirmed apoptosis as the primary mode of cell death in INO-A-treated Jurkat cells. INO-A treatment for only 30 min resulted in a significant increase of tail moment which suggests that DNA damage is an early apoptotic signal. Further flow cytometric assessment of the superoxide anion level confirmed that INO-A induced DNA damage was mediated with a concomitant generation of reactive oxygen species (ROS). Investigation on the thiols revealed an early decrease of free thiols in 30 min after 50 μM INO-A treatment. Using tetramethylrhodamine ethyl ester, a potentiometric dye, the loss of mitochondrial membrane potential (MPP) was observed in INO-A-treated cells as early as 30 min. The INO-A-induced apoptosis progressed with the simultaneous activation of caspases-2 and -9 which then led to the processing of caspase-3. Taken together, these data demonstrate that INO-A induced early oxidative stress, DNA damage and loss of MMP which subsequently led to the activation of an intrinsic pathway of apoptosis in Jurkat cells.