Multiomics of early epileptogenesis in mice reveals phosphorylation and dephosphorylation-directed growth and synaptic weakening

To investigate the phosphorylation-based signaling and protein changes occurring early in epileptogenesis, the hippocampi of mice treated with pilocarpine were examined by quantitative mass spectrometry at 4 and 24 h post-status epilepticus at vast depth. Hundreds of posttranscriptional regulatory proteins were the major early targets of increased phosphorylation. At 24 h, many protein level changes were detected and the phosphoproteome continued to be perturbed. The major targets of decreased phosphorylation at 4 and 24 h were a subset of postsynaptic density scaffold proteins, ion channels, and neurotransmitter receptors. Many proteins targeted by dephosphorylation at 4 h also had decreased protein abundance at 24 h, indicating a phosphatase-mediated weakening of synapses. Increased translation was indicated by protein changes at 24 h. These observations, and many additional indicators within this multiomic resource, suggest that early epileptogenesis is characterized by signaling that stimulates both growth and a homeostatic response that weakens excitability.

Subcellular analysis of blood-brain barrier function by micro-impalement of vessels in acute brain slices

The blood-brain barrier (BBB) is a tightly and actively regulated vascular barrier. Answering fundamental biological and translational questions about the BBB with currently available approaches is hampered by a trade-off between accessibility and biological validity. We report an approach combining micropipette-based local perfusion of capillaries in acute brain slices with multiphoton microscopy. Micro-perfusion offers control over the luminal solution and allows application of molecules and drug delivery systems, whereas the bath solution defines the extracellular milieu in the brain parenchyma. Here we show, that this combination allows monitoring of BBB transport at the cellular level, visualization of BBB permeation of cells and molecules in real-time and resolves subcellular details of the neurovascular unit. In combination with electrophysiology, it permits comparison of drug effects on neuronal activity following luminal versus parenchymal application. We further apply micro-perfusion to the human and mouse BBB of epileptic hippocampi highlighting its utility for translational research and analysis of therapeutic strategies.

Circuit-selective cell-autonomous regulation of inhibition in pyramidal neurons by Ste20-like kinase

Maintaining an appropriate balance between excitation and inhibition is critical for neuronal information processing. Cortical neurons can cell-autonomously adjust the inhibition they receive to individual levels of excitatory input, but the underlying mechanisms are unclear. We describe that Ste20-like kinase (SLK) mediates cell-autonomous regulation of excitation-inhibition balance in the thalamocortical feedforward circuit, but not in the feedback circuit. This effect is due to regulation of inhibition originating from parvalbumin-expressing interneurons, while inhibition via somatostatin-expressing interneurons is unaffected. Computational modeling shows that this mechanism promotes stable excitatory-inhibitory ratios across pyramidal cells and ensures robust and sparse coding. Patch-clamp RNA sequencing yields genes differentially regulated by SLK knockdown, as well as genes associated with excitation-inhibition balance participating in transsynaptic communication and cytoskeletal dynamics. These data identify a mechanism for cell-autonomous regulation of a specific inhibitory circuit that is critical to ensure that a majority of cortical pyramidal cells participate in information coding.

Terminomics Methodologies and the Completeness of Reductive Dimethylation: A Meta-Analysis of Publicly Available Datasets

Methods for analyzing the terminal sequences of proteins have been refined over the previous decade; however, few studies have evaluated the quality of the data that have been produced from those methodologies. While performing global N-terminal labelling on bacteria, we observed that the labelling was not complete and investigated whether this was a common occurrence. We assessed the completeness of labelling in a selection of existing, publicly available N-terminomics datasets and empirically determined that amine-based labelling chemistry does not achieve complete labelling and potentially has issues with labelling amine groups at sequence-specific residues. This finding led us to conduct a thorough review of the historical literature that showed that this is not an unexpected finding, with numerous publications reporting incomplete labelling. These findings have implications for the quantitation of N-terminal peptides and the biological interpretations of these data.

Genetic characterization of Curraleiro Pé-Duro bovine breed from a conservation herd of Brazilian semiarid

Curraleiro Pé-Duro is a rustic bovine taurine breed found in Northeast of Brazil; this breed has decreased its production potentially in order to adapt to the region environment conditions. Consequently, it is under risk of extinction and is maintained at a preservation center in Piauí State, Brazil, as a source of genetic material adapted to local conditions. We analyzed genetic variability of this breed using microsatellite markers. Sixty animals were genotyped using 11 microsatellite loci normally used for paternity tests in bovines. The observed number of alleles ranged from 5 to 9, and the effective number of alleles ranged from 2.01 to 4.64. The Shannon index ranged from 0.949 to 1.669. The expected heterozygosity ranged from 0.510 to 0.798. Polymorphism information content values ranged from 0.453 to 0.751. Divergence from Hardy-Weinberg equilibrium was significant and the mean FIS value was 0.010. We conclude that this breed still has some genetic diversity, but with evident risk due to genetic drift caused by current breeding management. It will be necessary to insert animals from other herds to obtain the desired level of genetic variability in this breed remnant.

Prolonged acceptance of skin grafts induced by B cells places regulatory T cells on the histopathology scene

The participation of regulatory T (Treg) cells in B cell-induced T cell tolerance has been claimed in different models. In skin grafts, naive B cells were shown to induce graft tolerance. However, neither the contribution of Treg cells to B cell-induced skin tolerance nor their contribution to the histopathological diagnosis of graft acceptance has been addressed. Here, using male C57BL/6 naive B cells to tolerize female animals, we show that skin graft tolerance is dependent on CD25⁺ Treg cell activity and independent of B cell-derived IL-10. In fact, B cells from IL-10-deficient mice were able to induce skin graft tolerance while Treg depletion of the host inhibited 100% graft survival. We questioned how Treg cell-mediated tolerance would impact on histopathology. B cell-tolerized skin grafts showed pathological scores as high as a rejected skin from naive, non-tolerized mice due to loss of skin appendages, reduced keratinization and mononuclear cell infiltrate. However, in tolerized mice, 40% of graft infiltrating CD4⁺ cells were FoxP3⁺ Treg cells with a high Treg:Teff (effector T cell) ratio (6:1) as compared to nontolerized mice where Tregs comprise less than 8% of total infiltrating CD4 cells with a Treg:Teff ratio below 1:1. These results render Treg cells an obligatory target for histopathological studies on tissue rejection that may help to diagnose and predict the outcome of a transplanted organ.

Genetic differentiation in natural populations of Lutzomyia longipalpis (Lutz & Neiva) (Diptera: Psychodidae) with different phenotypic spot patterns on tergites in males

Entomological surveys in the state of Maranhão have recorded morphologically distinct populations of Lutzomyia longipalpis (Lutz & Neiva). Some populations have one pair of spots (1S) on the fourth tergite, while others have two pairs (2S) on the third and fourth tergites of males. In the present study we investigated the degree of genetic polymorphism among four populations in the municipalities of Caxias, Codó and Raposa, in the state of Maranhão, Brazil, by using RAPD (Random Amplified Polymorphic DNA) markers. A total of 35 loci were identified, of which 30 were polymorphic. The highest polymorphism was observed with primer OPA 4, which produced 11 different profiles. Genetic diversity was assessed using grouping methods that produced a dendrogram in which the genotypes could be clearly separated into two main clades according to the number of spots on the male abdominal tergites. One cluster contained the populations from Caxias and Codó, and the other was formed by the populations from Raposa and Codó. The results of our RAPD analysis showed a clear separation between the populations with one and two pairs of spots. The epidemiologic significance of this genetic differentiation should be investigated in future studies.

High frequency of lamivudine resistance mutations in Brazilian patients co-infected with HIV and hepatitis B

This study analyzed the genotype distribution and frequency of lamivudine (LAM) and tenofovir (TDF) resistance mutations in a group of patients co-infected with HIV and hepatitis B virus (HBV). A cross-sectional study of 847 patients with HIV was conducted. Patients provided blood samples for HBsAg detection. The load of HBV was determined using an "in-house" real-time polymerase chain reaction. HBV genotypes/subgenotypes, antiviral resistance, basal core promoter (BCP), and precore mutations were detected by DNA sequencing. Twenty-eight patients with co-infection were identified. The distribution of HBV genotypes among these patients was A (n = 9; 50%), D (n = 4; 22.2%), G (n = 3; 16.7%), and F (n = 2; 11.1%). Eighteen patients were treated with LAM and six patients were treated with LAM plus TDF. The length of exposure to LAM and TDF varied from 4 to 216 months. LAM resistance substitutions (rtL180M + rtM204V) were detected in 10 (50%) of the 20 patients with viremia. This pattern and an accompanying rtV173L mutation was found in four patients. Three patients with the triple polymerase substitution pattern (rtV173L + rtL180M + rtM204V) had associated changes in the envelope gene (sE164D + sI195M). Mutations in the BCP region (A1762T, G1764A) and in the precore region (G1896A, G1899A) were also found. No putative TDF resistance substitution was detected. The data suggest that prolonged LAM use is associated with the emergence of particular changes in the HBV genome, including substitutions that may elicit a vaccine escape phenotype. No putative TDF resistance change was detected after prolonged use of TDF.

Barriers to treatment of hepatitis C in HIV/HCV coinfected adults in Brazil

The objective of this study was to assess the prevalence of barriers to interferon treatment in a population of HIV/HCV coinfected patients. A cross-sectional study was conducted at two AIDS Outpatient Clinics in Brazil. The study included all HIV infected patients followed at these institutions from January 2005 to November 2007. Medical records of 2,024 HIV-infected patients were evaluated. The prevalence of anti-HCV positive patients among them was 16.7%. Medical records of HCV/HIV coinfected patients were analyzed. 189 patients with the following characteristics were included in our study: mean age 43 years; male gender 65%; former IDUs (52%); HCV genotype 1 (66.4%); HCV genotype 3 (30.5%); median CD4+ T cell count was 340 cells/mm³. Among 189 patients included in the analyses, only 75 (39.6%) were considered eligible for HCV treatment. The most frequent reasons for non-treatment were: non-compliance during clinical follow-up (31.4%), advanced HIV disease (21.9%), excessive alcohol consumption or active drug use (18.7%), and psychiatric disorders (10.1%).

CONCLUSIONS

In Brazil, as in elsewhere, more than half of HIV/HCV coinfected patients (60.4%) have been considered not candidates to received anti-HCV treatment. The main reasons may be deemed questionable: non-adherence, drug abuse, and psychiatric disease. Our results highlight the importance of multidisciplinary teams to optimize the access of coinfected patients to HCV treatment.

Activity and growth efficiency of heterotrophic bacteria in a salt marsh (Ria de Aveiro, Portugal)

Bacterial utilization of monomers is recognized as an important step in the biogeochemical cycling of organic matter. In this study we have compared the heterotrophic activity of bacterial communities from different micro-habitats within a salt marsh environment (Ria de Aveiro, Portugal) in order to establish spatial patterns of bacterial abundance, monomer turnover rates (Tr) and bacterial growth efficiency (BGE). Differences in bacterial abundance and activity could be found between distinct plant rhizospheres. BGE tended to be lower at Halimione portulacoides banks, when compared to Sarcocornia perennis subsp. perennis banks which, on the contrary, showed the highest bacterial densities. Experiments of amendment of natural samples with organic and inorganic supplements indicated that salt marsh bacteria are not strongly regulated by salinity but the increased availability of labile organic matter causes a significant metabolic shift towards mineralization.

Anti-herpes simplex virus effect of a seed extract from the tropical plant Licania tomentosa (Benth.) Fritsch (Chrysobalanaceae)

Incubation of acyclovir-resistant herpes simplex virus type 1 (ACVr-HSV1), during infection of the HEp-2 cell culture, with an extract prepared from the seeds of Licania tomentosa (Benth.) Fritsch (Chrysobalanaceae) species impaired the productive replication of this virus in a concentration-dependent manner. The extract was able to inhibit extracellular virus (virucidal effect) and also interfered with a very early event of cell infection, at a non-cytotoxic concentration.

Analysis of peptidogalactomannans from the mycelial surface of Aspergillus fumigatus

Peptidogalactomannans (pGMs) from mycelium of two strains of Aspergillus fumigatus were fractionated by Cetavlon precipitation and size exclusion chromatography and their carbohydrate structures analysed using methylation-fragmentation analysis, partial acetolysis and 13C-nuclear magnetic resonance spectroscopy. The most significant difference between the pGMs of the two strains was the degree of branching and the proportion of non-reducing ends of alpha-D-Manp and beta-D-Galf units. Methylation data showed that the pGM from AF 2109 contained alpha-D-Manp and beta-D-Galf non-reducing end units in a proportion of 3:1 while, in contrast, the proportion of these structures in pGM from AF 2140 was 7:1, resulting in a highly branched structure. The immunoreactivity of the pGM fractions was tested by indirect immunofluorescence. The fractions were also tested in an ELISA system with rabbit antiserum raised to whole cells of A. fumigatus NCPF 2140 and with serum from patients with either proven aspergilloma or ABPA. The carbohydrate moiety of the pGM appears to be responsible for the antigenicity. Periodate treatment, partial acid hydrolysis and beta-elimination removed most of the antibody binding capacity.

An improved technique for a stapled transabdominal esophagojejunostomy

BACKGROUND

In the performance of a stapled transabdominal esophagojejunostomy there are two main technical problems involved and related to a difficult surgical exposure. One is the placement of the purse-string suture and the second is the insertion of the anvil of the circular intraluminal stapler into the distal esophagus.

METHODS

These technical difficulties can be overcome by opening just the anterior wall of the esophagus at the anastomosis level, leaving the posterior wall intact.

RESULTS

The integrity of the posterior wall avoids retraction of the mucosa, allowing the esophagus to remain opened for the placement of a through and through purse-string suture under direct vision. It also acts as a conduit for the insertion of the anvil of the circular intraluminal stapler.

CONCLUSIONS

The technique described herein avoids stay sutures, purse-string instruments, and forceful instrumental dilatation of the distal esophagus, making these very important operative steps much easier, safer, and more reliable.

Risks from occupational and dietary exposure to mevinphos

Mevinphos (trade name, Phosdrin), a category 1 organophosphorus insecticide, has been used mainly as a cleanup pesticide for vegetable crops. A risk assessment for occupational and dietary exposure to mevinphos was initiated because of the high acute toxicity of the compound. Repetitive dosing with mevinphos did not cause any discernible histopathological effects in mice or rats, nor was it oncogenic in either species. The principal toxic effects of mevinphos, both short- and long term, were due to inhibition of cholinesterase activity. Consequently, potential adverse effects from short-term exposures were the primary concern. A human no-observed-effect level (0.025 mg/kg) for cholinergic signs was used as the regulatory basis for calculating margins of safety (MOSs) for potential acute dietary and short-term occupational exposures. Estimates of exposure to mixer/loaders, pilots, and flaggers associated with aerial application of mevinphos were based on passive dosimetry. Because no acceptable exposure studies for work tasks associated with ground application of mevinphos were available, surrogate data based on ground application of oxydemeton-methyl were used. Exposure estimates for field workers and harvesters relied on measured dislodgeable foliar residues of mevinphos and transfer factors generated from studies of other active ingredients. MOSs for mean acute occupational exposure of mixer/loader/applicators associated with ground application and of harvesters working in fruit trees were less than the value conventionally recommended to protect people from the toxic effects of mevinphos. MOSs for the 95th percentile of short-term worker exposure for all mixer/loader work categories associated with mevinphos application were also inadequate. Calculated MOSs for potential acute dietary exposure to measured residue levels of mevinphos were adequate for the various population subgroups. However, 25 of the USEPA tolerances for mevinphos on agricultural commodities were not adequate to protect for the toxic effects of mevinphos from theoretical acute dietary exposure to one or more population subgroups if commodities are consumed with residues at the tolerance level. When the mean short-term occupational exposures were combined with potential acute dietary exposure, the MOSs for mixer/loaders engaged in aerial applications, as well as ground applications, were inadequate to protect people from the toxic effects of mevinphos. As mitigation of the estimated excessive occupational exposures did not appear possible, both California and the USEPA were preparing to cancel registration of the product. However, an agreement was worked out between the manufacturer and the two agencies that ended production for domestic use but allowed existing stocks in the channels of trade to continue to be used for a limited period.

Haemodynamic effects of pressure-controlled ventilation versus volume-controlled ventilation in patients submitted to cardiac surgery

OBJECTIVE

To compare the haemodynamic effects of pressure-controlled ventilation (PCV) with volume-controlled ventilation (VCV) in patients after cardiac surgery.

DESIGN

Prospective clinical study.

SETTING

Post-operative cardiac surgical ICU.

SUBJECTS

Twenty sequential elective adult patients with no previous chronic lung disease and aged less than 70 years old.

INTERVENTIONS

One hour after ICU admission and receiving mechanical ventilation utilising sinusoidal flow, patients were divided into two groups according to cardiac index (CI): group I: CI > 2.5 l/min/M2 and group II: CI < 2.5 l/min/M2. They were submitted randomly to 15 minutes' PC or VC mode, a 30-minute wash-out period of mechanical ventilation with a sinusoidal flow pattern, and then alternate PC or VC mode for 15 more minutes. Data were statistically compared using analysis of variance (ANOVA) with a significance level of 5%. Sedatives and muscle relaxants were given as necessary.

ENDPOINTS

Data were obtained at the end of 15 minutes under each ventilatory mode, observing a 30-minute interval between each.

MEASUREMENTS

Standard cardiorespiratory parameters were measured or calculated using conventional monitoring (including cardiac output), Qs/Qt, A-aDO2 alveolar-arterial oxygen difference, peak inspiratory pressure, mean airway pressure and dynamic compliance (C).

RESULTS

No significant differences between PCV and VCV modes, or between groups, were seen in MPAP, MAP, PCWP, RAP, heart rate, O2ER, VO2I, Paw, C, A-aDO2 and Qs/Qt. However, DO2I (p = 0.0063), LVSWI, (p = 0.0001) and RVSWI (p = 0.0053) showed a statistically significant difference between groups I and II. No influence of VCV or PCV on these parameters was seen. There was a slight significant difference between groups for PVR (p = 0.0205). In contrast, CI (p = 0.0001) and SVR (p = 0.0062) showed significant differences among groups, but also a significantly favourable effect of PCV over VCV (p = 0.0239 and p = 0.0318 respectively). Finally, a significant reduction (p = 0.0001) in peak inspiratory pressure with PCV was observed.

CONCLUSION

PC and VC ventilatory modes had comparable effects on patients with preserved or depressed cardiac output. Patients ventilated with PCV showed significantly higher values for cardiac index, a decreased SVR, as well as significantly lower values for inspiratory pressure when compared with VCV patients.

Interleukin 2 receptor membrane bound and in soluble form in the aqueous humor and peripheral blood of patients with acute untreated uveitis

Uveitis is a manifestation of various chronic inflammatory arthritic conditions. There are considerable data implicating abnormalities of immune function in the etiopathogenesis of uveitis. We evaluated the percentage of cells expressing interleukin 2 (IL-2) receptor (membrane bound) and the levels of soluble IL-2 in the blood and aqueous humor of patients in various rheumatic diseases and acute untreated uveitis. Our findings showed increased IL-2 receptors (IL-2R) and soluble IL-2 receptors on the aqueous humor of patients with uveitis when compared to healthy controls. These results suggest an immunoregulatory role of IL-2R in acute uveitis and raises the possibility that its detection may be useful in management.

Xenobiotic metabolizing enzyme activities in rat, mouse, monkey, and human testes

The capacity of the testis to metabolize xenobiotics has been proposed to play a role in the susceptibility of different species to testicular toxicity. Since species differences in testicular xenobiotic metabolizing enzyme activities are not well documented, the primary objective of the present study was to compare enzyme activities in subcellular fractions prepared from rat, mouse, monkey, and human testes. In microsomal fractions, enzyme activities measured were pentoxyresorufin O-dealkylase (PROD), ethoxyresorufin O-dealkylase (EROD), and epoxide hydrolase (mEH). In cytosolic preparations, epoxide hydrolase (cEH) and glutathione S-transferase (cGST) activities were measured. PROD activity was not detectable in any of the species studied, while it was readily detected in liver microsomes used as a positive control. Although EROD activity was low, it was measurable in testicular microsomes from rat and mouse, but not monkey or human. No marked species differences in cEH activity were found. In contrast, mEH activity was low in the monkey, intermediate in the rat, and highest in the human and mouse. cGST activity was significantly lower in the two primate species compared with the rat and the mouse. The levels of activity of the xenobiotic metabolizing enzymes studied were generally more than an order of magnitude lower in the testis as compared to the liver. However, in rat and mouse, the levels of mEH and cGST activities in testis were relatively similar to hepatic levels. Overall, these data indicate that species differences in capacity to metabolize xenobiotics may play a role in differential sensitivity to testicular toxicants.

Catabolism of epoxy fatty esters by the purified epoxide hydrolase from mouse and human liver

Epoxymethylsterate, 9,10- and 12,13-epoxymethyloleates, and a mixture of isomers of epoxymethylarachidonate and diepoxymethylstearate were synthesized, and their metabolic rates were measured using crude and purified cytosolic epoxide hydrolase. Hepatic epoxide hydrolase was purified from human samples and clofibrate-fed mice by affinity chromatography. The major metabolites under these conditions of all the epoxy fatty esters were their vicinal diols whose structures were confirmed by GC-MS. 12,13-Epoxymethyloleate was metabolized faster than 9,10-epoxymethyloleate and other epoxy fatty esters, but all substrates were turned over rapidly. This rapid turnover suggests that epoxy fatty acids may be endogenous substrates for the cytosolic epoxide hydrolase.

Effects of hepatic inducers on testicular epoxide-metabolizing enzymes in the rat and mouse

Testicular toxicants have become of increasing importance necessitating a better understanding of the possible role of testicular xenobiotic metabolism. The responsiveness of testicular microsomal epoxide hydrolase (mEH), cytosolic epoxide hydrolase (cEH), and cytosolic glutathione S-transferase (cGST) to hepatic inducers was studied in sexually mature male F344 rats and CD-1 mice. The hepatic inducers employed were phenobarbital (PB), beta-naphthoflavone (BNF), and butylated hydroxyanisole (BHA) which are known to induce cytochrome P-450, cytochrome P-448, and cGST, respectively. Hepatic mEH, cEH and cGST activities were assessed as positive controls. Measurable activities of all enzymes studied were present in the testes of both rats and mice. PB, BNF, and BHA produced the expected effects on mEH, cEH, and cGST in rat and mouse livers, whereas the testes were generally nonresponsive to the inducers. Induction of testicular cGST by PB occurred in mice but not rats and was the only testicular effect produced by the hepatic inducers in this study.

Cytosolic epoxide hydrolase in human placenta

It has been shown that cytosol from human term placenta contains cytosolic epoxide hydrolase activity. This cytosolic epoxide hydrolase was enriched more than 700-fold by affinity chromatography and appears similar to the enzyme from mouse and human liver in terms of molecular mass (Mr 59,000) and antigenic reactivity.

Epoxide-metabolizing enzymes in mammary gland and liver from BALB/c mice and effects of inducers on enzyme activity

Epoxide hydrolases (EC 3.3.2.3) (EH) are hydrolytic enzymes which may play an important role in the activation and detoxification of mammary carcinogens. In this study, microsomal, cytosolic, and cholesterol epoxide hydrolases along with glutathione S-transferase were characterized in liver and mammary gland from nulliparous and lactating BALB/c mice and from mice transplanted with preneoplastic hyperplastic outgrowths. Clofibrate, butylated hydroxyanisole, and beta-naphthoflavone were used to induce EH. Significant epoxide hydrolysis was observed in microsomal and cytosolic subcellular fractions assayed with cis- and trans-stilbene oxide, benzo(a)pyrene-4,5-oxide, and cholesterol epoxide. The hydrolysis rates were significantly different for nulliparous and lactating animals, in both mammary gland and liver. Clofibrate increased the activity of all forms of EH in liver, but not mammary gland. Butylated hydroxyanisole and beta-naphthoflavone appeared to induce cytosolic glutathione S-transferase as well as some, but not all, forms of EH in liver and mammary gland regardless of hormonal stimuli. The inducers produced different effects in mammary gland as compared with liver. This may be due to either differing amounts of inducer reaching the target site or different regulation of the enzymes in mammary gland and liver. Hyperplastic outgrowths and liver from hyperplastic outgrowth-transplanted animals demonstrated significantly different EH and cytosolic glutathione S-transferase activities from those of nulliparous and lactating animals. This observation offers preliminary evidence that levels of epoxide-metabolizing enzymes are altered when mammary tissue is transformed. Mammary gland cytosolic EH was purified by affinity chromatography and compared to that from liver by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, enzyme-linked immunosorbent assay, isoelectric focusing, and enzyme inhibition by 4-phenylchalcone oxide. Cytosolic EH from the mammary gland appears to be identical to the liver enzyme by all the above mentioned biochemical and biophysical parameters.

Affinity purification of cytosolic epoxide hydrolase using derivatized epoxy-activated Sepharose gels

Improved affinity chromatography procedures for the purification of cytosolic epoxide hydrolase are described. An earlier affinity purification method using immobilized 7-methoxycitronellyl thiol (MCT) sporadically produced final enzyme preparations containing major impurities. To eliminate these impurities, we tested alternate ligands, spacer arms, and ligand concentrations. A series of alkyl and aryl thiols coupled to epoxy-activated Sepharose were found to exhibit markedly different binding characteristics as compared with commercially available alkyl- and aryl-Sepharose gels. Using one of these new matrices, benzylthio-Sepharose, cytosolic epoxide hydrolase from mouse liver was purified over 100-fold, appeared homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and was obtained with 60-90% recovery of enzyme activity. The impurities previously observed with the MCT-Sepharose procedure were reduced or eliminated by using an MCT ligand concentration of 5 microequivalents per gram or less. MCT-Sepharose and benzylthio-Sepharose provide rapid and convenient one-step procedures for obtaining purified cytosolic epoxide hydrolase from numerous species and tissues.

Affinity purification of cytosolic epoxide hydrolase from human, rhesus monkey, baboon, rabbit, rat and mouse liver

An affinity purification system based on elution of cytosolic epoxide hydrolase from a methoxycitronellyl thiol ligand with 4-azidochalcone oxide was applied to a variety of samples including liver from human, monkey, baboon, rabbit, rat and mouse as well as mammary gland from mouse. Hepatic tissues yielded a major 58 kDa band on SDS-PAGE, but the system had to be modified slightly to remove a 33 kDa band for rat. All of the affinity purified hydrolases showed similar properties with regard to substrate selectivity, pH dependence and mobilities on SDS-PAGE.

Xenobiotic biotransformation in livers and lungs of adult black-tailed deer: comparison with domestic goat and sheep

1. The capacity of liver and lung tissue of black-tailed dear (Odocoileus hemionus columbianus) to biotransform xenobiotics was compared in vitro to the domestic sheep and goat. Donor animals were all females of varying ages. Tissues from the black-tailed deer were collected in the wild. A variety of biotransformation enzymes were measured in both microsomal and cytosolic fractions. 2. Deer liver was lower in total cytochrome P450 concentration, but mono-oxygenase activities were greater compared to sheep and goat. The opposite was true for the lung. 3. Epoxide hydrolase activities were significantly different in deer vs sheep and goat. 4. In general, both hepatic and pulmonary activities were more similar between sheep and goat than either species compared to the deer, however, the magnitude of the hepatic differences did not exceed 5-fold. 5. Based on these limited results, there is no reason to discredit the sheep or goat as a toxicity testing model for deer.

Epoxide hydrolysis in the cytosol of rat liver, kidney, and testis. Measurement in the presence of glutathione and the effect of dietary clofibrate

The hydrolysis of trans- and cis-stilbene oxide and benzo[a]pyrene-4,5-oxide was measured in cytosol and microsomes of liver, kidney, and testis of control and clofibrate-fed rats. Significant levels of nonprotein sulfhydryls were detected in cytosol from liver (4.6 mM) and testis (1.5 mM). Glutathione was moderately stable in these fractions and interfered with the partition assays as conjugates were retained in the aqueous phase along with diols. When the products were separated by thin-layer chromatography, significant amounts of glutathione-conjugates were found to have been formed in the cytosol of liver and testis. Overnight dialysis or preincubation of cytosol with 0.5 mM diethylmaleate eliminated conjugate formation without affecting diol production. In dialyzed cytosol from clofibrate-fed rats (0.5%, 14 days), the rates of hydrolysis of trans-stilbene oxide were 506, 171, and 96% of controls for liver, kidney, and testis, respectively, and 126% of controls in liver microsomes. Rates of hydrolysis of cis-stilbene oxide were 149, 172, and 96% of controls in microsomes and 154, 124, and 91% of controls in cytosols from livers, kidneys, and testis of clofibrate-fed rats respectively. Hydrolysis of benzo[a]pyrene-4,5-oxide was similar to that of cis-stilbene oxide. Conjugation of the cis-stilbene oxide with glutathione was detected in cytosols from all three tissues with lesser amounts in the microsomes from liver and kidneys. After clofibrate treatment, the rates of this activity were 200, 173, and 95% of controls in cytosol from liver, kidneys and testis, and 203 and 202% of controls in microsomes from liver and kidneys respectively. These results indicate that epoxide hydrolysis and conjugation in rat liver and kidney are responsive to clofibrate treatment and support other evidence which suggests that hydrolysis of cis- and trans-stilbene oxides in cytosol is catalyzed, in part, by distinct enzymes.

Procarcinogen activation by rat and human mammary extracts

Sprague-Dawley rat mammary gland is extremely sensitive to tumorigenesis by single or multiple doses of several polycyclic aromatic hydrocarbons. We obtained quantitative data on the in vitro mutagenic activation of several procarcinogens by 9000 g supernatant fraction (S9) from rat mammary gland using the Ames test. Mutagenic activation was shown to be dependent on a nicotinamide adenine dinucleotide phosphate (NADPH) generating system. An S9 preparation from mammary tissue of lactating Sprague-Dawley rats was shown to activate 2-aminoanthracene (2-AA). A polychlorinated biphenyl mixture of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) given to rats greatly raised the specific activity (revertant TA98 colonies/mg S9 protein) of the mammary tissue using 2-AA as a test carcinogen, and permitted detection of 2,4-diaminoanisole (DAA) and 2,7-diaminofluorene (DAF) activation. Procarcinogens 2-aminofluorine (2-AF), benzo[a]pyrene (BP) and aflatoxin (AFL) B1 were not detectably activated by mammary gland. Mutagenesis produced in mammary S9 activation of 2-AA, DAA or DAF was significantly inhibited by alpha-naphthoflavone (alpha NF) but was inhibited minimally by metyrapone (MP). Human mammary tumor cell lines (734B, SkBr3, MDA-MD-330) possessed inducible procarcinogen metabolizing activities similar to those found in S9 of rat mammary tissue. We demonstrated a simple and convenient use of the Ames test to characterize activation of many potential mutagens and carcinogens for mammary gland. When a test compound such as 2-AA was used, selective enzyme induction and inhibition was demonstrated.

Comparison of crude and affinity purified cytosolic epoxide hydrolases from hepatic tissue of control and clofibrate-fed mice

An affinity purification procedure was developed for the cytosolic epoxide hydrolase based upon the selective binding of the enzyme to immobilized methoxycitronellyl thiol. Several elution systems were examined, but the most successful system employed selective elution with a chalcone oxide. This affinity system allowed the purification of the cytosolic epoxide hydrolase activity from livers of both control and clofibrate-fed mice. A variety of biochemical techniques including pH dependence, substrate preference, kinetics, inhibition, amino acid analysis, peptide mapping, Western blotting, analytical isoelectric focusing, and gel permeation chromatography failed to distinguish between the enzymes purified from control and clofibrate-fed animals. The quantitative removal of the cytosolic epoxide hydrolase acting on trans-stilbene oxide from 100,000g supernatants, allowed analysis of remaining activities acting differentially on cis-stilbene oxide and benzo[a]pyrene 4,5-oxide. Such analysis indicated the existence of a novel epoxide hydrolase activity in the cytosol of mouse liver preparations.

Metabolism of 2-aminoanthracene by BALB/c and C57BL mammary epithelium in vitro

Aromatic primary amines, activated by P-450-dependent mixed-function oxidases have been shown to be mutagenic and carcinogenic in mammary gland of rodents. In this study, we compared 2-aminoanthracene (2AA) metabolism and inhibition in primary mammary gland cultures of BALB/c and C57BL mice. We sought to establish whether the rate or extent of metabolism was strain dependent as observed with polycyclic aromatic hydrocarbons even though the metabolic process would be different. Cells from either strain of mouse were uninjured by doses of 2AA up to 20 microM but produced polar metabolites of 2AA, some of which apparently formed covalent bonds with cellular macromolecules. In each case, covalent binding was inhibited by alpha-napthoflavone (alpha-NF), a mixed-function oxidase inhibitor. Any notable strain differences in 2AA metabolism and disposition was not observed. Results indicate that mouse mammary epithelial cells are capable of producing reactive metabolites of 2AA, probably via mixed-function oxidation. Thus, metabolic activation of 2AA in breast tissue may induce mutagenesis in mammary epithelium. The inhibitory effects of alpha-NF suggest that this compound may be of interest as a potential anti-carcinogen for the mammary gland.

Stimulation of S-9 fraction metabolism in rat liver and breast by vital dyes

The vital dyes neutral red (NR), methylene blue (MB) and trypan blue (TB) induced microsomal enzymes that metabolize the chemical carcinogens 2-aminoanthracene (2AA), 6-aminochrysene (6AC) and diaminofluorene (DAF). The Ames test was used as a method of assessing the amount of microsomal enzyme activity that occurred in rat breast and liver when treated with NR, MB, and TB. Livers were more readily induced than mammary glands of midpregnant rats. Liver S-9 fraction from rats treated with vital dyes showed an increase in revertant colonies for 2AA, DAF, and 6AC over that from untreated rats whereas breast S-9 fraction from rats treated with vital dyes showed an increase in revertant colonies for 2AA over untreated.