Evaluation of bisphenol A glucuronidation according to UGT1A1*28 polymorphism by a new LC-MS/MS assay

The endocrine disruptor bisphenol A (BPA) is a frequently used chemical in the manufacture of consumer products. In humans, BPA is extensively metabolized to BPA glucuronide (BPAG) by different UDP-glucuronosyltransferase (UGT) isoforms. The study has been performed with the intention to improve the accuracy of published physiologically based pharmacokinetic models and to improve regulatory risk assessments of BPA. In order to gain insight into intestine, kidney, liver, and lung glucuronidation of BPA, human microsomes of all tested organs were used. BPAG formation followed Michaelis-Menten kinetics in the intestine and kidney, but followed substrate inhibition kinetics in the liver. Human lung microsomes did not show glucuronidation activity towards BPA. While the liver intrinsic clearance was very high (857 mL min(-1)kg body weight(-1)), the tissue intrinsic clearances for the kidney and intestine were less than 1% of liver intrinsic clearance. Since BPA is a UGT1A1 substrate, we postulated that the common UGT1A1*28 polymorphism influences BPA glucuronidation, and consequently, BPA detoxification. Hepatic tissue intrinsic clearances for UGT1A1*1/*1, UGT1A1*1/*28, and UGT1A1*28/*28 microsomes were 1113, 1075, and 284 mL min(-1)kg body weight(-1), respectively. Prior to microsomal experiments, the bioproduction of BPAG and stable isotope-labeled BPAG (BPAG(d16)) was performed for the purpose of the reliable and accurate quantification of BPAG. In addition, a sensitive LC-MS/MS analytical method for the simultaneous determination of BPA and BPAG based on two stable isotope-labeled internal standards was developed and validated. In conclusion, our in vitro results show that the liver is the main site of BPA glucuronidation (K(m) 8.9 μM, V(max) 8.5 nmol min(-1) mg(-1)) and BPA metabolism may be significantly influenced by a person's genotype (K(m) 10.0-13.1 μM, V(max) 3.4-16.2 nmol min(-1) mg(-1)). This discovery may be an important fact for the currently on-going worldwide BPA risk assessments and for the improvement of physiologically based pharmacokinetic models.     

Epilepsy surgery in tuberous sclerosis: a systematic review

PURPOSE: Tuberous sclerosis complex (TSC) is often associated with intractable epilepsy. Although epilepsy surgery has gained interest in recent years uncertainties exist about which patients are good surgical candidates. A systematic review of the available literature has been undertaken to assess the overall outcome of epilepsy surgery and identify risk factors of seizure recurrence. METHODS: We searched MEDLINE, Embase, and bibliographies of reviews and book chapters to identify articles published in English since 1960. Twenty-five articles, describing postoperative seizure outcome and type of surgery in 177 TSC patients, were included in this study. Seizure outcome was analyzed both as seizure freedom and good outcome, including patients with >90% seizure reduction. RESULTS: Seizure freedom was achieved in 101 patients (57%). Seizure frequency was improved by > 90% in 32 patients (18%). Moderate or severe intellectual disability (IQ < 70) (RR 1.8; 95% CI 1.2-2.8) and the presence of tonic seizures (RR 1.7; 95 % CI 1.2-2.4) were related to seizure recurrence. CONCLUSIONS: A relation between multiple seizures types with early onset, multiple cortical tubers and multifocal epileptogenicity, and poor outcome is not supported by this systematic analysis. Although there is considerable variation among studies reviewed here, the literature suggests that resective surgery may offer benefit in a selected population of TSC patients with drug-resistant epilepsy.     

Elevated intrathecal antibodies against the medium neurofilament subunit in multiple sclerosis

Neurofilaments are cytoskeletal proteins localized within axons, which may interact with the immune system during and following tissue destruction in multiple sclerosis (MS). Antibodies against the medium neurofilament subunit synthesized intrathecally may reflect axonal damage in MS patients. Both immunoglobulin G (IgG) and M (IgM) responses against the purified native medium subunit of neurofilaments (NFM) using enzyme-linked immunosorbent assay (ELISA) were determined in paired serum and cerebrospinal fluid samples obtained from 49 MS patients, 16 normal controls (CN), 21 control patients with miscellaneous diseases (CD) and 14 patients with neurodegenerative disorders (CDEG). Intrathecal production of IgM and IgG antibodies to NFM were elevated in MS patients compared with the CN or CD groups (p < 0.04 for IgM, p < 0.01 for IgG). The increase was present in all the MS courses (relapsing-remitting, primary and secondary progressive). Similar local anti-NFM IgG and IgM synthesis occurred in the MS and CDEG groups. MS patients with short and long disease duration did not differ in terms of their anti-NFM IgM and IgG responses. Repeated examinations showed stable intrathecal anti-NFM production. Intrathecal IgG and IgM antibodies against NFM were increased in MS patients and may serve as a potential marker for axonal pathology. The extent of anti-NFM levels did not correspond to any individualized clinical profiles of MS patients.     

Prevention of glucocorticoid induced osteoporosis with alendronate or alfacalcidol: relations of change in bone mineral density, bone markers, and calcium homeostasis

OBJECTIVE: To explore the relation of changes in measures of bone turnover and changes in bone mineral density (BMD) of the lumbar spine and total hip over 18 months in a double-blinded, randomized trial, comparing the effect of alfacalcidol (101 patients) versus alendronate (100 patients) on BMD in patients who recently started treatment with glucocorticoids for various rheumatic diseases. METHODS: Associations between changes in serum procollagen type I C-propeptide (P1CP), fasting urine N-terminal telopeptide of type I collagen (NTx), serum calcium, parathyroid hormone (PTH), osteocalcin, and change from baseline in BMD over 18 months were explored with regression and correlation analyses. RESULTS: In both treatment groups, there was a statistically significant decrease in NTx. In the alfacalcidol group there was also a significant increase in P1CP and osteocalcin, in contrast to the alendronate group, but BMD in the alfacalcidol decreased versus an increase in the alendronate group (p < 0.001). In neither treatment group were changes in biochemical measures correlated with the change in BMD, with the exception of a negative correlation in the alendronate group between changes in total hip BMD and NTx. Use of alendronate resulted in an increased PTH in 27 patients, but the increase in BMD of these patients was not statistically significantly different compared to patients taking alendronate with normal PTH levels. CONCLUSION: Changes in BMD were not associated with changes in bone measures, with the exception of NTx in the alendronate group. For the patient taking glucocorticoids in clinical practice, the value of serial assessment of bone markers is low; changes in markers are no substitute for changes in BMD. ClinicalTrials.gov number: NCT00138983.     

Suboptimal recognition of a T cell epitope of the major dog allergen Can f 1 by human T cells

We have previously proposed that mammalian lipocalin allergens are recognized suboptimally by the human immune system due to their homology with endogenous lipocalins. Here, we have characterized in detail the human T cell recognition of one of the previously identified T cell epitopes of the major dog allergen Can f 1, contained in peptide p105–120. A panel of peptide analogues (altered peptide ligands, APLs) of p105–120 was tested on two specific T cell clones restricted by different human leukocyte antigen (HLA) alleles. Interestingly, we identified for both of the clones several heteroclitic APLs that were capable of stimulating them at 10–30-fold lower concentrations than the natural peptide. Moreover, one of the heteroclitic APLs identified with the T cell clones, L115F, was observed to induce a stronger polyclonal T cell response than the natural allergen peptide from the peripheral blood mononuclear cells (PBMCs) of six Can f 1-allergic subjects studied. The heteroclitic APLs bound with the same affinity as p105–120 to common HLA-DR- and HLA-DP-alleles, suggesting that their improved stimulatory capacity is attributable to a more efficient T cell receptor (TCR) recognition rather than increased HLA binding. Collectively, our data suggest that p105–120 is recognized suboptimally by human T cells. This may contribute to the allergenicity of Can f 1.