Affinity-based and in a single step purification of recombinant horseradish peroxidase A2A isoenzyme produced by Pichia pastoris

Horseradish peroxidase (HRP) is an oxidoreductase enzyme and oxidizes various inorganic and organic compounds. It has wide application areas such as immunological tests, probe-based test techniques, removal of phenolic pollutants from wastewater and organic synthesis. HRP is found in the root of the horseradish plant as a mixture of different isoenzymes, and it is very difficult to separate these enzymes from each other. In this regard, recombinant production is a very advantageous method in terms of producing the desired isoenzyme. This study was performed to produce HRP A2A isoenzyme extracellularly in Pichia pastoris and to purify this enzyme in a single step using a 3-amino-4-chloro benzohydrazide affinity column. First, codon-optimized HRP A2A gene was amplified and inserted into pPICZαC. So, obtained pPICZαC-HRPA2A was cloned in E. coli cells. Then, P. pastoris X-33 cells were transformed with linearized recombinant DNA and a yeast clone was cultivated for extracellular recombinant HRP A2A (rHRP A2A) enzyme production. Then, the purification of this enzyme was performed in a single step by affinity chromatography. The molecular mass of purified rHRP A2A enzyme was found to be about 40 kDa. According to characterization studies of the purified enzyme, the optimum pH and ionic strength for the rHRP A2A isoenzyme were determined to be 6.0 and 0.04 M, respectively, and o-dianisidine had the highest specificity with the lowest Km and Vmax values. Thus, this is an economical procedure to purify HRP A2A isoenzyme without time-consuming and laborious isolation from an isoenzyme mixture.

Characterization of fowl aviadenovirus species in backyard flocks in Turkey

Fowl aviadenovirus infections show a worldwide distribution in poultry at all ages and the incidence of the disease is increasing year after year. Most of the studies have been exhibited the situation of the disease in commercial chickens especially in broilers but there is not sufficient data to estimate in backyards. Totally 389 internal organ samples were collected from 56 flocks from suspicious backyard chickens at ages between 10-35 weeks. Samples were tested by PCR method and nucleotide sequences of hexon genes were used for phylogenetic analyses and comparing with other FAdV sequences submitted to GenBank. Of the 389 samples, 23.9% were found FAdV positive and 30.4% (17/56) of the flocks sampled in the study were infected. This is the first study that was carried out in backyards and two species (D and C) and four serotypes (FAdV-8a, FAdV-3, FAdV-4, and FAdV-10) have been discovered for the first time in Turkey. To understand the epidemiology of FAdV in Turkey and to get enough information about species and serotypes further large scale national studies should be carried out to determine the severity of FAdV infections and to plan control strategies.

Molecular docking and inhibition profiles of some antibiotics on lactoperoxidase enzyme purified from bovine milk

Antibiotics are generally used for human and veterinary applications to preserve and to control microbial diseases. Milk has a biologically significant enzyme known as lactoperoxidase (LPO) that is a member of peroxidase family. In metabolism, LPO has ability to catalyze the transformation of thiocyanate (SCN^-) to hypothiocyanite (OSCN^-) that is an antibacterial agent and the reaction occurs with hydrogen peroxide. In this work, LPO inhibition effects of some antibiotics including cefazolin, oxytetracycline, flunixin meglumine, cefuroxime, tylosin, vancomycin, chloramphenicol and lincomycin were tested. Among the antibiotics cefazolin was indicated the strongest inhibitory efficacy. The half maximal inhibitory concentration (IC₅₀) and the inhibition constant (K_i) values of cefazolin were found as 8.19 and 34.66 µM, respectively. It was shown competitive inhibition. 5-Methyl-1,3,4-thiadiazol-2-yl moiety activity plays a key role in the inhibition mechanism of cefazolin.Communicated by Ramaswamy H. Sarma.

Lactoperoxidase inhibition of some natural phenolic compounds: Kinetics and molecular docking studies

The inhibition effects of some phenolic compounds from natural products such as taxifolin, resveratrol, olivetol, cynarine, and phloretin on bovine milk lactoperoxidase (LPO) enzyme were examined. For this aim, LPO was purified by the affinity chromatography technique with a yield of 77.68% in 421.32 times. The kinetic value, K_i , was calculated from the equations obtained from drawn graphs. In order to discover inhibition mechanism of phenolic compounds, induced fit docking process was performed on the LPO receptors. The binding affinity of the compounds was calculated and at the best-scored ligand-receptor complex, residues responsible for enzyme inhibition were detected. As a result, this molecule demonstrated the potential inhibitory effect on LPO. According to the results of kinetic study. It has shown a noncompetitive inhibition effect, Phloretin's K_i value was determined by 48.89 ± 14.22 nM. PRACTICAL APPLICATIONS: There are natural antimicrobial systems, such as the lactoperoxidase (E.C.1.11.1.7; LPO) system, which eliminates the harmful effects of microorganisms in milk. The chemical reactions in this system are catalyzed by the LPO. In the dairy industry, the LPO system is considered critical for the preservation of pasteurized milk, yogurt, raw milk, and cheese. The system is used for improvement the protection condition of milk at high temperatures.

A hierarchical assembly of flower-like hybrid Turkish black radish peroxidase-Cu2+ nanobiocatalyst and its effective use in dye decolorization

Effective dye decolorization in wastewater still shows a big challenge. Although the biological methods, especially using enzymes, offer alternative and effective process for dye degradation and overcome the limitations of chemical and physical methods such as the instability, lack of reusability and high cost of free enzymes strictly, which limit their use in many scientific and technical applications. Enzymes rapidly lose their activities in aqueous solutions and against environmental changes due to their very susceptibility and unfavorable conformations. Herein, we report preparation of the enzyme-inorganic hybrid nanostructures with flower-like shape consisting of Turkish black radish peroxidase and Cu²⁺ metal ions using an encouraging enzyme immobilization approach. The peroxidase-Cu²⁺ hybrid nanoflowers (NFs) exhibited enhanced stability and activity towards various pH values and provided excellent dye decolorization efficiency for Victoria blue (VB) dye with more than 90% within 1 h. The NFs were also repeatedly used in efficient and caused 77% VB decolorization efficiency even at tenth cycles. However, to the best of our knowledge, for the first time, we prepared peroxidase enzyme isolated from Turkish black radish incorporated NFs and used them for dye decolorization. We believe that the NFs can be promising materials for dye decolorization in real wastewater treatment.

Secondary Sulfonamides as Effective Lactoperoxidase Inhibitors

Secondary sulfonamides (4a–8h) incorporating acetoxybenzamide, triacetoxybenzamide, hydroxybenzamide, and trihydroxybenzamide and possessing thiazole, pyrimidine, pyridine, isoxazole and thiadiazole groups were synthesized. Lactoperoxidase (LPO, E.C.1.11.1.7), as a natural antibacterial agent, is a peroxidase enzyme secreted from salivary, mammary, and other mucosal glands. In the present study, the in vitro inhibitory effects of some secondary sulfonamide derivatives (4a–8h) were examined against LPO. The obtained results reveal that secondary sulfonamide derivatives (4a–8h) are effective LPO inhibitors. The K_i values of secondary sulfonamide derivatives (4a–8h) were found in the range of 1.096 × 10⁻³ to 1203.83 µM against LPO. However, the most effective inhibition was found for N-(sulfathiazole)-3,4,5-triacetoxybenzamide (6a), with K_i values of 1.096 × 10⁻³ ± 0.471 × 10⁻³ µM as non-competitive inhibition.

A multi-site analysis of the association between black carbon concentrations and vehicular idling, traffic, background pollution, and meteorology during school dismissals

A study was performed to assess the relationship between black carbon (BC), passing traffic, and vehicular idling outside New York City (NYC) schools during student dismissal. Monitoring was performed at three school sites in East Harlem, the Bronx, and Brooklyn for 1month per year over a two-year period from November 2006-October 2008. Monitoring at each site was conducted before and after the Asthma Free School Zone (AFSZ) asthma reduction education program was administered. Real-time equipment with a one-minute averaging interval was used to obtain the BC data, while volume counts of idling and passing school busses, trucks, and automobiles were collected each minute by study staff. These data were matched to ambient PM(2.5) and meteorology data obtained from the New York State Department of Environmental Conservation. A generalized additive model (GAM) model was run to examine the relationship between BC concentration and each variable while accounting for site-to-site differences. F-tests were employed to assess the significance of each of the predictor variables. The model results suggested that variability in ambient PM(2.5) concentration contributed 24% of the variability in transformed BC concentration, while variability in the number of idling busses and trucks on the street during dismissal contributed 20% of the variability in transformed BC concentration. The results of this study suggest that a combination of urban scale and local traffic control approaches in combination with cessation of school bus idling will produce improved local BC concentration outside schools.

Detection of mycoplasma species in turkeys by culture and polymerase chain reaction

The purpose of the present study was to investigate the presence of pathogenic mycoplasma species in the turkey population of Turkey. Tracheal samples randomly collected from a total of 624 apparently healthy meat-type turkeys at a commercial abattoir located in the north of the country were examined by culture and genus- and species-specific polymerase chain reaction (PCR) assays for mycoplasma. In the direct plating onto solid specific media, mycoplasma growth was observed from 1.4% (9/624) of the samples, which were confirmed to belong to the Mycoplasma genus by genus-specific PCR. Mycoplasma iowae (MI) and M. meleagridis (MM) were identified by the species-specific PCR from eight and one of the samples, respectively. However, genus-specific PCR amplification was obtained from 2.6% (16/624) of the samples which produced turbidity in the liquid media. Interestingly, these positive samples were different from those obtained from solid agar and mycoplasma growth was not observed when the broth samples were inoculated onto solid media. In the species-specific PCR analysis of the broth samples, MI, MM and M. gallisepticum were identified from twelve, two and two samples, respectively. The inconsistency between the results obtained from liquid and solid media raises questions about the efficiency of isolation procedures for mycoplasma and this warrants further investigation.

Associations of PM2.5 and black carbon concentrations with traffic, idling, background pollution, and meteorology during school dismissals

An air quality study was performed outside a cluster of schools in the East Harlem neighborhood of New York City. PM(2.5) and black carbon concentrations were monitored using real-time equipment with a one-minute averaging interval. Monitoring was performed at 1:45-3:30 PM during school days over the period October 31-November 17, 2006. The designated time period was chosen to capture vehicle emissions during end-of-day dismissals from the schools. During the monitoring period, minute-by-minute volume counts of idling and passing school buses, diesel trucks, and automobiles were obtained. These data were transcribed into time series of number of diesel vehicles idling, number of gasoline automobiles idling, number of diesel vehicles passing, and number of automobiles passing along the block adjacent to the school cluster. Multivariate regression models of the log-transform of PM(2.5) and black carbon (BC) concentrations in the East Harlem street canyon were developed using the observation data and data from the New York State Department of Environmental Conservation on meteorology and background PM(2.5). Analysis of variance was used to test the contribution of each covariate to variability in the log-transformed concentrations as a means to judge the relative contribution of each covariate. The models demonstrated that variability in background PM(2.5) contributes 80.9% of the variability in log[PM(2.5)] and 81.5% of the variability in log[BC]. Local traffic sources were demonstrated to contribute 5.8% of the variability in log[BC] and only 0.43% of the variability in log[PM(2.5)]. Diesel idling and passing were both significant contributors to variability in log[BC], while diesel passing was a significant contributor to log[PM(2.5)]. Automobile idling and passing did not contribute significant levels of variability to either concentration. The remainder of variability in each model was explained by temperature, along-canyon wind, and cross-canyon wind, which were all significant in the models.

The ATP 30-a scale for measuring medical students' attitudes to psychiatry

The development and validation of a thirty item, Likert-type scale designed to measure medical students' attitudes to psychiatry-the ATP-30 (Attitudes Toward Psychiatry-30 items)-are described. We had hoped to demonstrate that 'attitude to psychiatry' was not a unitary matter but an amalgam of attitudes to a number of things to do with psychiatric practice. This hope was not fulfilled, as a unitary dimension was obtained. A positive change in the attitudes of students toward psychiatry was demonstrated in third and fourth medical year students in relation to exposure to psychiatry. Such a change was not demonstrable in two classes of occupational therapy students exposed to a course in psychiatry. The reasons for this difference between medical students and occupational therapy students are discussed-there possibly being important implications here for psychiatric curriculum planning in medical school. Lastly, we have demonstrated that the positive change in attitudes amongst medical students was transient rather than lasting-a matter which most studies of attitude change do not address. In spite of the apparent impermanence of the positive change in attitudes among medical students, there are a number of possible used to a scale such as the ATP-30, and these are discussed.

Sex-role ideology among practicing psychiatrists and psychiatric residents

The authors distributed a sex-role ideology questionnaire to practicing psychiatrists, psychiatric residents, university students, and groups of traditional and feminist women. Psychiatrists and psychiatric residents as a group were significantly more feminist in their ideology than university students and the traditional women's group but were less feminist than a group of feminist women. There were no differences between practicing psychiatrists and psychiatric residents. Overall, women were more feminist than men and increasing age was found to be associated with increasingly traditional ideology. These findings challenge the view that psychiatrists as a group have traditional views that make them part of a traditional medical power structure.

Continuing medical education: viewpoints of Canadian psychiatric residents

Continuing Medical Education (CME), relicensure and recertification are controversial issues for physicians today. The viewpoints of 142 Canadian psychiatric residents from 12 training centres across Canada were surveyed. The majority (73%) of the residents did not think that CME would pose a problem for them after certification. In fact, a large majority (77%) felt CME should be required after certification. Close to half of the residents favoured monitoring of CME by the Canadian Psychiatric Association. In contrast to these results, few favoured mandatory recertification. A formal relicensure examination was strongly repudiated. Individual reading and self-assessments as well as clinically oriented courses and workshops were the favoured methods of CME. Our recommendations arising from this survey are threefold. CME should remain a voluntary activity. The Canadian Psychiatric Association should be the monitoring body for CME for psychiatrists, and finally, individual readings and self-assessments should be used increasingly in providing CME.

Results of the first Canadian psychiatric knowledge self-assessment for residents

Two 150 multiple choice question examinations in Psychiatry were taken on a voluntary basis by 150 Canadian residents. The goals of these examinations were to promote skills and interest in self-education, provide detailed feedback to the participants, and to study various parameters which might be related to performance. The residents' self-assessments prior to the examinations, their year of residency training and age were significant predictors of performance. Being male and having enough time to study were also related to high scores. The methods of instruction as well as the studying variables were not related significantly to performance. These findings highlight the importance of self-assessments in the process of evaluation and of listening to residents' self-evaluations and requests for time to study. Increasing the number of self-assessment exercises and clarifying the knowledge requirements for the certification examination are recommended.

Development and validation of a sex-role ideology scale

Two studies are reported in which a scale measuring sex-role ideology was constructed, validated and cross-validated. Sex-role ideology was conceived as a system of sex-role beliefs forming a dimension with a traditional and a feminist pole. From an initial pool of 82 statements, 30 were selected that best discriminated between criterion groups of traditional and feminist women and that represented the heterogeneous content of sex roles. Half of the items are phrased in a feminist and half in a traditional direction. The scale was then cross-validated with new criterion groups. The internal consistency of the scale was shown through item-total correlations and split-half reliability (median r = .79). The test-retest reliability was .87.