A novel 7α-hydroxysteroid dehydrogenase: Magnesium ion significantly enhances its activity and thermostability.

7α-Hydroxysteroid dehydrogenase (7α-HSDH) plays an important role in the efficient biotransformation of taurochenodeoxycholic acid (TCDCA) to tauroursodeoxycholic acid (TUDCA). In this paper, a novel NADP(H)-dependent 7α-HSDH (named J-1-1) was discovered, heterologously expressed in Escherichia coli and biochemically characterized. J-1-1 exhibited high enzymatic activities. The specific activities of J-1-1 toward TCDCA, glycochenodeoxycholic acid (GCDCA) and ethyl benzoylacetate (EBA) were 188.3 ± 0.2, 217.6 ± 0.4, and 20.0 ± 0.2 U·mg-1, respectively, in 50 mM Glycine-NaOH, pH 10.5. Simultaneously, J-1-1 showed high thermostability; 73% of its activity maintained after heat treatment at 40 °C for 100 h. Particularly noteworthy is that magnesium ion could stabilize the structure of J-1-1, resulting in the enhancement of its enzymatic activity and thermostability. The enzymatic activity of J-1-1 increased 40-fold in the presence of 50 mM Mg2+, and T0.5 increased by approximately 6 °C. Furthermore, after heat treatment at 40 °C for 20 min, the control group only retained 52% of the residual enzyme activity, while the residual enzyme activity of the experimental group was still 77% of the J-1-1 enzyme activity with Mg2+ and without heat treatment. These properties of 7α-HSDH would be expected to contribute to more extensive applications in the biotransformation of related substrates.

Bioanalytical challenges and unique considerations to support pharmacokinetic characterization of bispecific biotherapeutics.

Compared with conventional (monospecific) therapeutics, bispecific protein therapeutics present unique challenges for pharmacokinetic (PK) characterization - namely, the characterization of multiple functional domains as well as the consideration of biotransformation or interference by the formation of antitherapeutic antibodies against each functional domain. PK characterization is essential to the success of the overall drug development plan and for molecules with multiple binding domains; multiple bioanalytical methods may be needed to answer critical questions for each phase of drug development. The number of bispecific protein therapeutics entering drug development continues to increase, and therefore, a bioanalytical strategy for the PK characterization of bispecific molecules and study of their in vivo structure-function relationship is needed. This review presents case studies and a regulatory perspective.

The potential role of pharmacogenomics and biotransformation in hypersensitivity reactions to paracetamol.

PURPOSE OF REVIEW: The aim of the present review is to discuss recent advances supporting a role of paracetamol metabolism in hypersensitivity reactions to this drug. RECENT FINDINGS: Recent developments in the identification of novel paracetamol metabolites, as well as in allele frequencies and functional effects of genetic variation leading to the bioavailablity of reactive paracetamol metabolites, have led to the identification of potential pharmacogenomic and metabolomic targets in studies seeking mechanisms involved in hypersensitivity reactions caused by this drug. Particularly relevant are identification of araquidonate metabolites, identification of specific-binding sequences for reactive paracetamol metabolite-protein adducts, and studies on the frequencies and the functional impact of duplication or multiduplication of genes involved in the formation of reactive metabolites, as well as complete gene deletion or deleterious mutations in genes involved in the detoxification of paracetamol reactive metabolites. In addition, recent evidence points to sex, ethnic origin and age as relevant factors in the production of reactive paracetamol metabolites. SUMMARY: High inter-individual variability in the production of reactive paracetamol metabolites exists, and factors leading to increased bioavailability of reactive paracetamol metabolites are being uncovered. Additional research is required to link these factors to paracetamol-induced hypersensitivity reactions.

Biotransformation of Dioscorea nipponica by Rat Intestinal Microflora and Cardioprotective Effects of Diosgenin.

Studying the biotransformation of natural products by intestinal microflora is an important approach to understanding how and why some medicines-particularly natural medicines-work. In many cases, the active components are generated by metabolic activation. This is critical for drug research and development. As a means to explore the therapeutic mechanism of Dioscorea nipponica (DN), a medicinal plant used to treat myocardial ischemia (MI), metabolites generated by intestinal microflora from DN were identified, and the cardioprotective efficacy of these metabolites was evaluated. Our results demonstrate that diosgenin is the main metabolite produced by rat intestinal microflora from DN. Further, our results show that diosgenin protects the myocardium against ischemic insult through increasing enzymatic and nonenzymatic antioxidant levels in vivo and by decreasing oxidative stress damage. These mechanisms explain the clinical efficacy of DN as an anti-MI drug.

Drug-induced lupus erythematosus.

Drug-induced lupus erythematosus (DILE) refers to a condition whose clinical, histological, and immunological features are similar to those seen in idiopathic lupus erythematosus but that occurs when certain drugs are taken and resolves after their withdrawal. Over 90 drugs have been linked to DILE to date and the list is growing. Like idiopathic lupus erythematosus, DILE has systemic, subacute cutaneous, and chronic cutaneous forms. A correct diagnosis is very important, as this condition usually resolves after withdrawal of the offending drug.

[The benefits of using basophil activation test as a diagnostic tool prior to specific immunotherapy with inhalant allergens]. / Korzysci z wykonywania testu aktywacji bazofilów w kwalifikacji do immunoterapii swoistej w alergii wziewnej.

BACKGROUND: Routine qualification for specific immunotherapy (SIT) is based on clinical history and skin prick tests (SPT) or specific IgE (sIgE). In cases of discordance between these two, basophil activation test (BAT) may be decisive. The aim of the present study was to determine the specificity and sensitivity of BAT, sIgE, and SPT, and to analyse cases, in which clinical data and SPT alone would result in wrongful qualification for SIT. PATIENTS AND METHODS: BAT results and sIgE levels to Dermatophagoides pteronyssinus (Dp) and Dermatophagoides farinae (Df) were determined in 52 pediatric patients qualified for SIT based on clinical history and positive SPT. The group included 21 children qualified for SIT with birch or timothy grass, used as reference for specificity and sensitivity calculations for BAT, sIgE and SPT. RESULT: The sensitivity and specificity of BAT, using SPT as "gold standard" was 96.9% and 88.9% for Dp, and 89.3% and 100% for Df, respectively and the sensitivity and specificity of sIgE were 89.7%, 88.9% for Dp, and 92.9% and 94.4% for Df. When using BAT as "gold standard", the sensitivity and specificity of SPT was 90% and 90.5% for Dp, 92% and 84,6% for Df, and these indices for sIgE were 87.1% and 90.5% for Dp, 100% and 87.5% for Df. BAT did not confirm the initial qualification for SIT in 2 patients, revealing an unspecific basophil activation. Negative nasal provocation test ultimately confirmed the false-positive SPT, which could be explained by the co-existence of urticaria in those children. In further 2 children qualified for SIT with timothy and birch, BAT revealed lack of reactivity to respective allergens. Altogether BAT helped in avoiding unnecessary SIT in 4 out of 52 children (7.7%). CONCLUSIONS: In most cases, SPT, sIgE and BAT provide comparable information, however, SPT results care is advised in patients with co-existing urticaria. BAT is useful in verifying the actual relevance of allergens selected for SIT and helps in avoiding long-lasting, arduous, costly, and ineffective immunotherapy of wrongly qualified cases.

Biotransformación de carbón de bajo rango por bacterias aisladas de microhábitats influenciados por residuos de carbón / Biotransformation of low rank coal by bacteria isolated from environments influenced by coal residue

Se describió la capacidad de cinco cepas bacterianas para transformar un carbón de bajo rango (CBR), para ello se evaluaron cepas aisladas de microhábitats con presencia de partículas procedentes de los procesos de almacenamiento y lavado de carbón en la mina El Cerrejón (Colombia). Se realizaron ensayos de solubilización de CBR en medio de cultivo sólido y líquido, además de la decoloración de sustancias húmicas (SH) extraídas del CBR. Todas las bacterias evaluadas presentaron capacidad para biotransformar CBR en medio sólido, esta actividad es mayor cuando el CBR ha sido pretratado con ácido nítrico; en medio líquido se alcanzó una pérdida de peso de CBR hasta del 37% por acción de una cepa de Acinetobacter baumannii, acompañada de la aparición de hasta 8,06 mg/ml-1 de sustancias solubles con absorbancia a 465 nm; los cambios en el pH del medio sugieren que la actividad biotransformadora de CBR está asociada a la liberación de sustancias alcalinas; finalmente, se encontró evidencia para sugerir que las SH presentes en el CBR son transformadas por cometabolismo, posiblemente mediante reacciones de depolimerización, decoloración y repolimerización.

in this study were evaluated five bacterial strains isolated from microhabitats with high content of coal particles generated from storage and washing processes, in "The Cerrejón” open coal mine (Colombia), their ability to biotransform a low rank coal (LRC) was described by testing solubilization on solid and liquid culture medium, as well as bleaching of humic substances (HS) extracted from LRC. All tested bacteria showed ability to biotransform LRC on solid medium, this activity is greater when the LRC has been pretreated with nitric acid; in liquid medium LRC reached 37% of weight loss by Acinetobacter baumannii strain, accompanied by the appearance of up to 6.8 mg/ml-1 of soluble substances with absorbance at 465 nm, changes in culture medium pH suggest that LRC biotransformations activity is associated with alkaline substances release, finally found evidence to suggest that HS contained within LRC are transformed by cometabolism, possibly by depolymerization reactions, bleaching and repolimerization.

A novel gamma-fitting statistical method for anti-drug antibody assays to establish assay cut points for data with non-normal distribution.

In recent years there has been growing recognition of the impact of anti-drug or anti-therapeutic antibodies (ADAs, ATAs) on the pharmacokinetic and pharmacodynamic behavior of the drug, which ultimately affects drug exposure and activity. These anti-drug antibodies can also impact safety of the therapeutic by inducing a range of reactions from hypersensitivity to neutralization of the activity of an endogenous protein. Assessments of immunogenicity, therefore, are critically dependent on the bioanalytical method used to test samples, in which a positive versus negative reactivity is determined by a statistically derived cut point based on the distribution of drug naïve samples. For non-normally distributed data, a novel gamma-fitting method for obtaining assay cut points is presented. Non-normal immunogenicity data distributions, which tend to be unimodal and positively skewed, can often be modeled by 3-parameter gamma fits. Under a gamma regime, gamma based cut points were found to be more accurate (closer to their targeted false positive rates) compared to normal or log-normal methods and more precise (smaller standard errors of cut point estimators) compared with the nonparametric percentile method. Under a gamma regime, normal theory based methods for estimating cut points targeting a 5% false positive rate were found in computer simulation experiments to have, on average, false positive rates ranging from 6.2 to 8.3% (or positive biases between +1.2 and +3.3%) with bias decreasing with the magnitude of the gamma shape parameter. The log-normal fits tended, on average, to underestimate false positive rates with negative biases as large a -2.3% with absolute bias decreasing with the shape parameter. These results were consistent with the well known fact that gamma distributions become less skewed and closer to a normal distribution as their shape parameters increase. Inflated false positive rates, especially in a screening assay, shifts the emphasis to confirm test results in a subsequent test (confirmatory assay). On the other hand, deflated false positive rates in the case of screening immunogenicity assays will not meet the minimum 5% false positive target as proposed in the immunogenicity assay guidance white papers.

The roles of drug metabolism in the pathogenesis of T-cell-mediated drug hypersensitivity.

PURPOSE OF REVIEW: The purpose of this review is to highlight recent studies on drug metabolism in T-cell-mediated reactions. Although the hapten theory and the danger hypothesis imply an important role of reactive metabolites in the pathogenesis of drug hypersensitivity, the more recent pi concept gives the central role to the parent drug. It is therefore important to have a broad vision on data supporting each theory to understand the potential role(s) of drug metabolism in T-cell-mediated hypersensitivity. RECENT FINDINGS: Reactive metabolites have been identified for most drugs associated with hypersensitivity. Recent studies have further characterized drug metabolism outside the liver, in key tissues such as the skin and immune cells. Localized drug metabolism is associated with oxidative stress, adduct formation and toxicity creating danger signals for antigen presenting cells, influencing whether a drug antigen will induce tolerance or immunity. SUMMARY: The involvement of metabolic drug activation in the initiation and propagation of hypersensitivity is intriguing since metabolites are generated in different quantities throughout the body, can be directly or indirectly toxic to cells, might stimulate innate immunity, and can bind to protein to generate neoantigens for cellular and humoral responses.

Interactions between immune and biotransformation systems in fish: a review.

In animals biotransformation and immune system are not totally independent, there are numerous functional interrelationships between these two systems. They are both implicated in the capacity of organisms to resist to a wide variety of environmental components such as viruses, bacteria and xenobiotics. It is known for a long time that the immune system functions as a physiologic system and interacts with all the other components of the organism including nervous or endocrine ones. In the same manner, the biotransformation system (especially the cytochrome P450 monooxygenases) is involved in the regulation of numerous hormone productions. In this way, many studies in mammals have revealed the possible interaction between immune and biotransformation systems. Among these interactions, the capacity of the activation of host defense mechanisms to down-regulate microsomal cytochrome P450 and the role of biotransformation system in the xenobiotic-mediated immunotoxicity have been underlined. Advances in the basic knowledge of fish immune and biotransformation systems should lead to a better understanding of the possible interactions between both systems and should improve fish health monitoring which is a crucial ecotoxicological goal.

Sex-specific effect of insulin-dependent diabetes 4 on regulation of diabetes pathogenesis in the nonobese diabetic mouse.

Many human autoimmune diseases are more frequent in females than males, and their clinical severity is affected by sex hormone levels. A strong female bias is also observed in the NOD mouse model of type I diabetes (T1D). In both NOD mice and humans, T1D displays complex polygenic inheritance and T cell-mediated autoimmune pathogenesis. The identities of many of the insulin-dependent diabetes (Idd) loci, their influence on specific stages of autoimmune pathogenesis, and sex-specific effects of Idd loci in the NOD model are not well understood. To address these questions, we analyzed cyclophosphamide-accelerated T1D (CY-T1D) that causes disease with high and similar frequencies in male and female NOD mice, but not in diabetes-resistant animals, including the nonobese diabetes-resistant (NOR) strain. In this study we show by genetic linkage analysis of (NOD x NOR) x NOD backcross mice that progression to severe islet inflammation after CY treatment was controlled by the Idd4 and Idd9 loci. Congenic strains on both the NOD and NOR backgrounds confirmed the roles of Idd4 and Idd9 in CY-T1D susceptibility and revealed the contribution of a third locus, Idd5. Importantly, we show that the three loci acted at distinct stages of islet inflammation and disease progression. Among these three loci, Idd4 alleles alone displayed striking sex-specific behavior in CY-accelerated disease. Additional studies will be required to address the question of whether a sex-specific effect of Idd4, observed in this study, is also present in the spontaneous model of the disease with striking female bias.

Immunostimulation of the chemical-induced carcinogenesis in the phase of initiation MH-G 0166.

It is postulated that the immune reaction on chemical carcinogens can inhibit or stimulate the chemical-induced carcinogenesis depending on the individual peculiarities of the synthesis of antibodies. Critical events take place on the barriers between external and internal media. Antibodies to chemical carcinogens, which are secreted into the digestive or bronchial tract, bind the environmental carcinogens and prevent them from penetrating into the blood through the epithelium and thereby inhibit the beginning of the tumour growth in any organs. On the contrary, the serum antibodies promote the penetration of carcinogens through the digestive and bronchial epithelia and thereby stimulate carcinogenesis in the proper organs. The other events take place in the organs such as breast and prostate where carcinogens are transported from the blood. Secretory antibodies bind carcinogens in the blood and transport them through the epithelium of these glands and thereby stimulate the tumour origin in these organs. Antibodies, which are not secreted into the ducts of breast and prostate, hold carcinogens in the blood and thereby inhibit carcinogenesis in these organs. Antibodies to steroid hormones function in the same way, i.e., secretory antibodies stimulate, while the serum antibodies inhibit the genetoxic action of the hormones on breast and prostate. The stimulation of carcinogenesis in the lymphoid cells is realized owing to hapten-specific binding of carcinogens by the membrane receptors of the corresponding clones. Antibodies to the natural inhibitors of carcinogenesis (retinoids, tocopherole, etc.) stimulate the beginning of the tumour growth. Antibodies to carcinogens and antiidiotypic antibodies to the cytochromes p-450 may act as abzymes, i.e., as cytochromes p-450 and thereby increase the level of the carcinogen metabolites.

Latent-TGF-beta: an overview.

The latency associated with the transforming growth factor-betas (TGF-betas) was discovered in 1984. Since the two publications on this subject in that year, there has been on average over sixty reports in which latency was the dominant theme for each of the past 10 years, proof enough of the interest in this field of growth factor research. As the mature 25 kD forms of the TGF-betas are required for them to exert their many, diverse biological effects, it was inevitable that an explanation of the structure and of the activation of the latent complexes be sought. This overview provides a description of these essential points. Now that it has been clearly shown that dysregulation of particular components of the TGF-beta signalling pathway is implicated in many human diseases, the activation of the latent TGF-beta complexes has taken on added importance. Technical improvements enable the distinction of active and latent TGF-beta proteins in vivo and have started to reveal anomalies in the control of activation in relation to various pathological situations.

Role of metabolic activation by cytochrome P450 in thioacetamide-induced suppression of antibody response in male BALB/c mice.

Effects of thioacetamide on antibody response to sheep red blood cells were investigated in male BALB/c mice. When mice were treated intraperitoneally with thioacetamide once, the antibody response was significantly suppressed at 200 mg/kg with hepatotoxicity. When mice were treated intraperitoneally with thioacetamide for 7 consecutive days, the antibody response was suppressed at 50 mg/kg without hepatotoxicity. To determine the possible role of metabolic activation by cytochrome P450 in thioacetamide-induced suppression of antibody response, mice were pretreated with phenobarbital intraperitoneally for 3 days, followed by intraperitoneal administration of 100 mg/kg of thioacetamide for 3 days. The elevated activities of serum aspartate aminotransferase and alanine aminotransferase by thioacetamide were potentiated by phenobarbital pretreatment. The suppression of antibody response by thioacetamide was potentiated by phenobarbital. In liver microsomes, the activities of P450 2B-specific enzymes were induced by phenobarbital. Our present results suggest that thioacetamide may require metabolic activation by P450 to its immunosuppressive form(s).

Effects of co-administration of butylated hydroxytoluene, butylated hydroxyanisole and flavonoids on the activation of mutagens and drug-metabolizing enzymes in mice.

Effects of co-administration of food additives and naturally occurring food components were studied on the activation of mutagens. Male mice (ddY) were given diets containing butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA) and flavone or flavanone (2,3-dihydroflavone) for two weeks and the ability of hepatic microsomes to activate aflatoxin B1, benzo[a]pyrene and N-nitrosodimethylamine was determined by the mutagenicity test. Co-administration of an antioxidant (0.1% BHT or 0.2% BHA in diet) and a flavonoid (0.1% flavone or 0.1% flavanone) resulted in additive effects on the activation of aflatoxin B1 and benzo[a]pyrene, while the activation of N-nitrosodimethylamine was not elevated significantly by the co-administration. To understand the mechanism for the additive effects, induction of specific isozymes of cytochrome P450 involved in the activation of the mutagens was studied. Co-administration of BHT (0.1%) and flavone (0.1%) increased markedly the levels of proteins and the activities of the enzymes related to the isozymes of CYP2A and CYP2B, while co-administration of BHA (0.2%) and flavanone (0.1%) elevated those related to CYP1A. Further, the activation of aflatoxin B1 and benzo[a]pyrene in hepatic microsomes was inhibited by the antibodies against these isozymes, which suggested that the enhanced activation of the mutagens by the co-administration might be mediated by the induction of these isozymes.

T cells ignore the parent drug propylthiouracil but are sensitized to a reactive metabolite generated in vivo.

The antithyroid drug propylthiouracil (PTU) is known to cause adverse immunological side effects, such as a lupus-like syndrome and vasculitic disorders. In vitro experiments have established that myeloperoxidase of activated neutrophils can oxidize PTU to the reactive intermediate propyluracil 2-sulfonate PTU-SO3-, and it has been proposed that PTU-SO3- might be responsible for the PTU-associated side effects. Here, using the direct popliteal lymph node assay (PLNA) in mice we found that PTU-SO3-, indeed, induced a T-cell-dependent primary PLN response, whereas the parent compound PTU failed to do so. As shown by adoptive transfer PLNA, splenic T cells of mice that had received four injections of PTU-SO3- mounted a specific secondary response to the reactive metabolite, but not to PTU. When homogenized peritoneal phagocytes, which had been incubated with PTU in vitro, were used as the antigen, a primary response in the direct PLNA was elicited, suggesting that the phagocytes contained the reactive metabolite. Moreover, T cells sensitized to the reactive metabolite PTU-SO3- were detected in mice that were undergoing long-term treatment with PTU plus an additional treatment with phorbol myristate acetate for stimulation of the oxidative metabolism of their phagocytic cells. Together, these findings support the concept that phagocytes oxidize PTU to its immunogenic metabolite, PTU-SO3-, which then, presumably via covalently binding to self-proteins, induces T cell sensitization.

Duck lymphocytes--V. Transformation responses to phorbol ester and calcium ionophore.

1. Lymphocytes purified from duck blood and spleen were cultured in the presence of phorbol 12-myristate 13-acetate (PMA) and the calcium ionophore A23187. Stimulation was assessed by the incorporation of [3H]thymidine after 3 days' culture. 2. PMA stimulated over a wide range of concentrations, with maximum stimulation at final concentrations of 5 x 10(-7)-5 x 10(-8) M/litre. A23187 was effective in the range 5 x 10(-6)-5 x 10(-7) M/litre and also, in some experiments using spleen lymphocytes, at 5 x 10(-11)-5 x 10(-12) M/litre. 3. Synergism was observed between PMA and A23187, the pattern depending on the concentrations of these reagents employed. Synergism was also observed between PMA and suboptimum concentrations of phytohaemagglutinin (PHA), wheat germ agglutinin (WGA), pokeweed mitogen (PWM) and Bandeiraea simplicifolia seed extract (BSS), but not with concanavalin A (Con A), lentil lectin (LL) or Helix pomatia lectin (HP). Similarly, synergism occurred between A23187 and WGA or PWM, but not with PHA, BSS, Con A, LL or HP. 4. Mitomycin C and cycloheximide inhibited the response of duck lymphocytes to PMA, A23187 and lectins. Cyclosporin A inhibited responses to lectins but not to PMA or A23187. Neither hydrocortisone nor indomethacin inhibited responses to lectins, PMA or A23187. 5. These results indicate that activation of duck lymphocytes occurs by virtue of similar intracellular messenger pathways to those operating in mammalian lymphocytes.