Low-cholesterol diet: enhancement of effect of CDCA in patients with gall stones.

Fifteen patients with gall stones who were taking chenodeoxycholic acid(CDCA) 15 mg/kg at bedtime participated in two separate experiments to investigate the effects of altering sterol intake on the cholesterol saturation index (SI) of fasting gall-bladder bile. In experiment I the 15 patients on an unrestricted diet had a SI of 0.87 +/- 0.04 (mean +/- SE of mean), which fell to 0.75 +/- 0.04 after one week in hospital on a diet of 100 mg cholesterol daily. In experiment II seven of the patients were given four different dietary regimens lasting one month each in random order as outpatients. On a diet of 600 mg of cholesterol daily the mean SI was 0.72 +/- 0.05, which fell to 0.67 +/- 0.05 when the patients were put on a 100 mg cholesterol diet. The addition of plant sterols (3 g daily) to both diets raised the mean SIs to 0.80 +/- 0.05 and 0.77 +/- 0.05 respectively. The percentage CDCA in bile was unaffected by alterations in the cholesterol and plant sterol intakes. We conclude that a low-cholesterol diet but not a high intake of plant sterols enhances the effect of CDCA in patients with gall stones.     

Effects of a Balanced Translocation between Chromosomes 1 and 11 Disrupting the DISC1 Locus on White Matter Integrity

Objective

Individuals carrying rare, but biologically informative genetic variants provide a unique opportunity to model major mental illness and inform understanding of disease mechanisms. The rarity of such variations means that their study involves small group numbers, however they are amongst the strongest known genetic risk factors for major mental illness and are likely to have large neural effects. DISC1 (Disrupted in Schizophrenia 1) is a gene containing one such risk variant, identified in a single Scottish family through its disruption by a balanced translocation of chromosomes 1 and 11; t(1;11) (q42.1;q14.3).

Method

Within the original pedigree, we examined the effects of the t(1;11) translocation on white matter integrity, measured by fractional anisotropy (FA). This included family members with (n = 7) and without (n = 13) the translocation, along with a clinical control sample of patients with psychosis (n = 34), and a group of healthy controls (n = 33).

Results

We report decreased white matter integrity in five clusters in the genu of the corpus callosum, the right inferior fronto-occipital fasciculus, acoustic radiation and fornix. Analysis of the mixed psychosis group also demonstrated decreased white matter integrity in the above regions. FA values within the corpus callosum correlated significantly with positive psychotic symptom severity.

Conclusions

We demonstrate that the t(1;11) translocation is associated with reduced white matter integrity in frontal commissural and association fibre tracts. These findings overlap with those shown in affected patients with psychosis and in DISC1 animal models and highlight the value of rare but biologically informative mutations in modeling psychosis.     

Recombinant human arginase toxicity in mice is reduced by citrulline supplementation

Human recombinant arginase I cobalt coupled to polyethylene glycol 5000 (HuArg I [Co]-PEG5000) achieved potent in vitro depletion of arginine from tissue culture medium and cytotoxicity to many cancer cell lines. The recombinant enzyme also produced tumor growth inhibition of hepatocellular carcinoma and pancreatic carcinoma xenografts. Although these results were promising, the therapeutic index was narrow. Toxicities were seen in normal cells in tissue culture. In vivo normal tissue injury occurred at doses twice the effective dose. The current study was conducted to define, in greater detail, the maximum tolerated dose (MTD), pharmacodynamics, and dose-limiting toxicities (DLTs) of twice-weekly intraperitoneal HuArg I [Co]-PEG5000 in Balb/c mice. Animal weight and survival were monitored, serum arginine levels measured, and complete blood cell counts, chemistries, necropsies, and histologies were performed. In addition, methods to ameliorate the HuArg I [Co]-PEG5000 adverse effects were tested. Supplemental l-citrulline was given concurrently with the arginase drug. The HuArg I [Co]-PEG5000 MTD in mice was 5 mg/kg twice weekly, and DLTs included weight loss and marrow necrosis. No other organ damage or changes in blood cell counts or chemistries were observed. Arginase reduced serum arginine levels from 60 μM to 4 to 6 μM. Supplemental l-citrulline given per os or daily subcutaneously reduced and delayed toxicities, and l-citrulline given twice daily subcutaneously completely prevented animal toxicities. On the basis of these results, we hypothesize that HuArg I [Co]-PEG5000, particularly with supplemental l-citrulline, may be an attractive therapeutic agent for argininosuccinate synthetase-deficient tumors.     

Structural and functional insights into DNA-end processing by the archaeal HerA helicase-NurA nuclease complex

Helicase-nuclease systems dedicated to DNA end resection in preparation for homologous recombination (HR) are present in all kingdoms of life. In thermophilic archaea, the HerA helicase and NurA nuclease cooperate with the highly conserved Mre11 and Rad50 proteins during HR-dependent DNA repair. Here we show that HerA and NurA must interact in a complex with specific subunit stoichiometry to process DNA ends efficiently. We determine crystallographically that NurA folds in a toroidal dimer of intertwined RNaseH-like domains. The central channel of the NurA dimer is too narrow for double-stranded DNA but appears well suited to accommodate one or two strands of an unwound duplex. We map a critical interface of the complex to an exposed hydrophobic epitope of NurA abutting the active site. Based upon the presented evidence, we propose alternative mechanisms of DNA end processing by the HerA-NurA complex.     

Retrospective analysis of treatment outcome in 315 patients with oligodendroglial brain tumors

Although chemotherapy with procarbazine, lomustine and vincristine (PCV) is considered to be well tolerated, side effects frequently lead to dose reduction or even discontinuation of treatment of oligodendroglial brain tumors. The primary objective of the analysis was to retrospectively compare progression-free survival (PFS) after PCV vs. PC chemotherapy (without vincristine to avoid side effects). Patients were retrospectively identified from a database containing our patients between 1990 and 2003. For the selected cases, all histopathology reports were re-evaluated by a local neuropathologist. Based on the updated histology data, patients were included in the study if they had at least one histological diagnosis of an oligodendroglial tumor. PFS after start of PCV (n = 61) and PC (n = 84) chemotherapy identical (median 30 months). Multivariate analysis adjusting for prognostic imbalances favouring the PC group showed a minor, statistically non-significant benefit for PCV (hazard ratio 0.81, 95% confidence interval 0.53–1.25; p = 0.346). Younger age (< 50 y) was a statistically significant predictor of longer PFS. Significant advantages in terms of overall survival after first diagnosis of oligodendroglial tumor (OS, n = 315) were found for patients < 50 y (p < 0.001), oligodendrogliomas versus oligoastrocytomas (p = 0.002), and WHO°II vs. °III (p < 0.001). Three risk groups regarding OS were identified. Findings support the hypothesis that PC may be as effective as PCV chemotherapy, while avoiding the additonal risks of vincristine. Younger age, lower tumor grade and histology of an oligodendroglioma were identified to be favorable prognostic factors.     

Effects of the Macrolide Drug Tylosin on Chronic Diarrhea in Rhesus Macaques (Macaca mulatta)

Diarrhea is the gastrointestinal disease most frequently encountered in captive rhesus macaques. The precise pathogenic mechanisms underlying chronic diarrhea in nonhuman primates are not well understood, but a persistent inflammatory component has been implicated strongly. This study evaluated the inflammatory changes in the colon of macaques with diarrhea and assessed the efficacy of a 10-d course of tylosin in a cohort of 21 animals with chronic diarrhea. Stool quality was evaluated daily, and fecal consistency was scored. Colonoscopies were performed; biopsy samples were characterized histologically and assayed for expression of TNFα mRNA. Blood samples collected pre-, mid-, and post-treatment were assayed for C-reactive protein (CRP). The results indicated that 63% of the animals receiving tylosin showed improvement in stool quality, compared with 10% in the sham-treated group. Histologically, 82% of animals in the tylosin-treated group had a reduction in the severity of colonic lesions post-treatment, compared with 40% of animals in the sham group. The amount of TNFα mRNA before treatment did not differ from that afterward in either tylosin- or sham-treated animals. CRP levels serially decreased in tylosin-treated monkeys; the average post-treatment CRP value for tylosin-treated animals was 11.96 ± 3.86 μg/ml compared with 26.48 ± 4.86 μg/ml for sham-treated controls. In conclusion, tylosin significantly improved the fecal consistency score, significantly decreased colonic inflammation, and significantly decreased serum CRP levels post-treatment in rhesus macaques with chronic diarrhea.Abbreviations: CRP, C-reactive protein; IBD, inflammatory bowel diseaseDiarrhea in captive nonhuman primates annually affects as many as 15% of animals in some colonies and can account for approximately 33% of deaths not related to research.³ Similarly at the California National Primate Research Center, chronic or recurrent liquid stool that is refractory to treatment is common and is a leading cause of animal death due to euthanasia because of poor condition and failure to respond to therapy. Clinical management of chronic diarrhea in nonhuman primates is often difficult and unrewarding. Multiple drugs commonly are used for treating chronic diarrhea in nonhuman primates and include tetracycline, metronidazole, and prednisone. These drugs also are used frequently in treating canine chronic enteropathies.^7,30 In addition to these drugs, the use of tylosin for the treatment of canine chronic diarrhea is becoming common practice. Tylosin can be effective in treating dogs with chronic or intermittent diarrhea, and this disorder is referred to as tylosin-responsive diarrhea.^29,30Tylosin is an antibiotic of the macrolide class; other drugs in this class include erythromycin, azithromycin, and clarithromycin. Tylosin is produced naturally by the bacterium Streptomyces fradiae, acts to inhibit bacterial protein synthesis by inhibiting the 50S ribosome, and is a bacteriostatic drug.¹⁹ Its antimicrobial activity is targeted against aerobic gram-positive organisms, some anaerobic Clostridium spp., some gram-negative bacteria (Helicobacter pylori, Haemophilus spp., Pasteurella spp., Legionella spp.), spirochetes, Cryptosporidium parvum, Chlamydia, and Mycoplasma organisms.^21,25 Campylobacter spp., which can be enteropathogenic and are common in nonhuman primates, are sensitive to tylosin,^7,14 whereas enteric microorganisms such as Escherichia coli and Salmonella spp. are intrinsically resistant.²² Tylosin is licensed for use as a broad-spectrum antibiotic (injectable or oral) for treatment of bacterial infections in livestock and is a common feed additive in food animal production.²¹Many antibiotics have been reported to have beneficial immunomodulatory effects on gut mucosa (for example, metronidazole and ciprofloxacin) and can alleviate chronic inflammation in diseases such as inflammatory bowel disease (IBD) or small intestinal bacterial overgrowth.⁷ Macrolide antibiotics, including tylosin, have been reported to have a positive treatment effect on canine enteropathies that resemble IBD.³⁰ Further, tylosin has been shown to reduce the severity of colonic lesions in a rat model of colitis induced by 2,4,6-trinitrobenzenesulfonic acid.¹⁵ In addition to having antimicrobial properties, tylosin likely has antiinflammatory effects that contribute to its effectiveness in treating diarrhea.^15,30Macrolides are widely used as antibacterial drugs. Clinical and experimental data now indicate that the effects of macrolides are not restricted to direct action on bacteria, but they also involve modulation of host defense mechanisms.^12,13 The nonantimicrobial, antiinflammatory properties of macrolides were first identified when patients receiving troleandomycin for the treatment of asthma had reduced need for steroids.²⁶ Most of the additional studies on the immunomodulatory effects of macrolides have been in human patients with diffuse panbronchiolitis or other chronic inflammatory respiratory diseases. The mechanism of the antiinflammatory activity of macrolide antibiotics is unclear. However, these antiinflammatory effects include decreased production of proinflammatory cytokines, such as IL8, IL1, IL6, and TNFα, and reduced neutrophil infiltration.^8,12,26Here we report the results of a study to evaluate the efficacy of tylosin for the treatment of chronic diarrhea in rhesus macaques.