Quantitative estimations of the contribution of different bile acid pathways to total bile acid synthesis in the rat

BACKGROUND & AIMS: Cholesterol degradation to bile acids occurs via "classic" or "alternative" bile acid biosynthetic pathways. The aim of this study was to assess the contributions of these two pathways to total bile acid synthesis in vivo. METHODS: Rats with biliary fistulas were infused with squalestatin for 24 and 48 hours; specific activities of cholesterol 7 alpha-hydroxylase (C7 alpha H) and sterol 27- hydroxylase (S27H) and rates of bile acid synthesis were determined. RESULTS: Continuous squalestatin infusion (15 micrograms/h) decreased C7 alpha H specific activities to 4% and 12% of paired biliary fistula controls at 24 and 48 hours, respectively (P < 0.05) without any changes in S27H specific activities (82% and 95% of controls). At 24 hours, bile acid synthesis decreased to 43% (P < 0.05) but returned to 87% at 48 hours (P = NS). Cholic acid synthesis decreased at 24 hours but returned to control levels at 48 hours. Similar changes in C7 alpha H, S27H, and bile acid synthesis were observed in primary rat hepatocytes after addition of squalestatin (1.0 mumol/L). CONCLUSIONS: In the face of persistent suppression of C7 alpha H and the classic pathway, an alternative pathway becomes a main pathway of bile acid synthesis capable of generating cholic and chenodeoxycholic acids. The observed induction of bile acid synthesis via an alternative pathway or pathways represents an important mechanism for maintenance of cholesterol homeostasis in the rat. (Gastroenterology 1997 Dec;113(6):1949-57)     

7 alpha-dehydroxylating bacteria enhance deoxycholic acid input and cholesterol saturation of bile in patients with gallstones

BACKGROUND & AIMS: Excessive deoxycholic acid (DCA) in the bile acid pool with cholesterol supersaturation of bile is prevalent in patients with cholesterol gallstones (CGs). This study examined whether this is caused by enhanced conversion of cholic acid (CA) to DCA by intestinal bacteria. METHODS: Ten patients with CGs with DCA excess (DCA/CA pool ratio, > 1.5) and 10 patients with low DCA (ratio, < 1.0) were compared for CA and DCA kinetics, ileal absorption of 75-Se-homotaurocholic acid (75-SeHCAT), and CA-7 alpha-dehydroxylation activity of the fecal microflora; the effects of ampicillin treatment on DCA excess were studied in 7 patients. RESULTS: Patients with DCA excess and low DCA differed (P < 0.01) in the pool size of CA (mean, 5.8 vs. 34) and DCA (28 vs. 11 mumol/kg) and DCA input (8.8 vs. 3.5 mumol.kg-1.day-1. Whereas 75-SeHCAT excretion was similar, CA-7 alpha-dehydroxylation activity and levels of fecal 7 alpha-dehydroxylation bacteria were 3- fold and 1000-fold higher (P < 0.01) in patients with DCA excess, respectively. Ampicillin treatment decreased (P < 0.02) CA-7 alpha- dehydroxylation activity and DCA pool size, expanded the CA pool to normal size, and lowered cholesterol saturation of bile. CONCLUSIONS: Increased CA-7 alpha-dehydroxylation activity of the intestinal microflora may be an important factor for CG formation or growth in these patients. (Gastroenterology 1996 Dec;111(6):1611-20)     

Therapy of severe aplastic anemia in young adults and children with allogeneic bone marrow transplantation

During an 8-year period, 28 young adults (median age 27 years) and 30 children (median age 10 years) with severe aplastic anemia have received allogeneic bone marrow transplantation (BMT) from major histocompatibility locimatched sibling donors after preparation with cyclophosphamide and total lymphoid irradiation (TLI). All recipients were previously transfused. Comparison of post-bone marrow transplantation events in adults and children reveals equivalent median time to engraftment, median duration of hospitalization, median Karnofsky assessment of activity, and equivalent low rejection rate. Although the incidence of moderate and severe acute graft-v-host disease (GVHD) and of extensive chronic GVHD was greater in adults than in children, the projected survival at 4 years of adults (67%; 95% confidence interval [CI] 49% to 85%) and of children (73%; 95% CI 57% to 89%) was equivalent. All survivors are transfusion-free and have normal peripheral blood counts. One of 28 adults and 2 of 30 children have experienced rejection, and 1 of these patients survives after a second transplant. No malignancies have been identified following transplantation. An unexpectedly high incidence of hypothyroidism has been detected and may be attributable to preparation of recipients with TLI. Therapy of severe aplastic anemia with allogeneic BMT after preparation with cyclophosphamide and TLI offers a high rate of transfusion-free survival and a low rejection rate in previously transfused young adults and children.     

Different response patterns of several ligands at the sphingosine-1-phosphate receptor subtype 3 (S1P3)

Background and purpose:

Recently, some ligands targeting the sphingosine-1-phosphate receptor subtype 3 (S1P₃) have become available. The characterization of these compounds was mainly based on one functional read-out system, although S1P₃ receptors are known to activate different signal transduction pathways. Therefore, this study pharmacologically characterizes these compounds using different assays.

Experimental approach:

Using CHO-FlpIn cells expressing the human S1P₃ receptor the potencies and maximal effects of S1P, FTY720-P, VPC23019, VPC23153 and VPC24191 were determined in three different assays [inhibition of cAMP accumulation, elevation of intracellular calcium concentrations ([Ca²⁺]_i) and S1P₃ receptor internalization].

Key results:

All compounds tested inhibited forskolin-induced cAMP accumulation, increased [Ca²⁺]_i and induced S1P₃ receptor internalization but with different potencies and maximal effects. S1P was the most potent compound in all assays followed by FTY720-P. The VPC compounds were generally less potent than S1P and FTY720-P. Regarding the maximal effects, all compounds except VPC23153, behaved as full agonists in the cAMP accumulation assay. In the calcium assay, FTY720-P, VPC23019 and VPC24191 displayed partial and VPC23153 weak partial agonist activity, relative to S1P. Interestingly, treatment with the G_i inactivator Pertussis toxin, did not affect S1P-induced [Ca²⁺]_i elevations but inhibited those in response to the other compounds, by about 50%.

Conclusions and implications:

This study demonstrated differential response patterns at the S1P₃ receptor for a range of ligands. These differences could indicate the presence of functional selectivity at this receptor as FTY720-P and the VPC compounds seemed to signal predominantly via G_i– whereas S1P activated G_i and G_q-coupled pathways.     

Poultry coccidiosis: recent advancements in control measures and vaccine development

Coccidiosis is recognized as the major parasitic disease of poultry and is caused by the apicomplexan protozoan Eimeria. Coccidiosis seriously impairs the growth and feed utilization of infected animals resulting in loss of productivity. Conventional disease control strategies rely heavily on chemoprophylaxis and, to a certain extent, live vaccines. Combined, these factors inflict tremendous economic losses to the world poultry industry in excess of USD 3 billion annually. Increasing regulations and bans on the use of anticoccidial drugs coupled with the associated costs in developing new drugs and live vaccines increases the need for the development of novel approaches and alternative control strategies for coccidiosis. This paper aims to review the current progress in understanding the host immune response to Eimeria and discuss current and potential strategies being developed for coccidiosis control in poultry.     

The filaggrin null genotypes R501X and 2282del4 seem not to be associated with psoriasis: results from general population study and meta‐analysis

Background Psoriasis vulgaris could be associated with the filaggrin null genotype since certain known susceptibility loci for psoriasis are shared with susceptibility loci for atopic dermatitis. Furthermore, filaggrin expression is lowered in psoriatic skin lesions but normally expressed in uninvolved skin. So far five relatively small patient‐based case‐control studies have rejected a possible association between psoriasis and the two most prevalent filaggrin null mutations, 2282del4 and R501X. Objectives To reinvestigate a possible association between psoriasis and filaggrin null mutation status by using cross‐sectional general population questionnaire data. Also, to perform a meta‐analysis including published studies that investigated the relation between filaggrin gene mutations R501X and 2282del4, respectively, and psoriasis vulgaris. Methods Between June 2006 and May 2008, a cross‐sectional study was performed in the general population in Copenhagen. A random sample of 7931 subjects aged 18–69 years was invited to participate in a general health examination including a questionnaire and 3471 (43.7%) participated. A total of 3335 (96.1%) individuals were filaggrin genotyped for the 2282del4 and R501X mutations. A meta‐analysis was undertaken to investigate the relation between filaggrin gene mutations and psoriasis vulgaris. Results The prevalence of self‐reported psoriasis was 6.7% among the 3240 respondents. The prevalence of the R501X and 2282del4 filaggrin null genotypes was 9.3% in subjects who reported psoriasis and 8.0% in subjects who did not report psoriasis (OR = 1.28; 95% CI = 0.74–1.89; P = 0.78). The meta‐analysis found no association between the filaggrin null genotypes R501X and 2282del4 and psoriasis (OR = 1.04; 95% CI = 0.81–1.35). Conclusions Psoriasis was not associated with the R501X and 2282del4 filaggrin null genotypes in a general population study and in a meta‐analysis on published studies.