Presence Of Other Classes Research Articles

Antibiotic Resistance of Bacillus cereus in Plant Foods and Edible Wild Mushrooms in a Province.

Bacillus cereus is a common pathogen causing foodborne diseases, secreting and producing a large number of toxins that can cause a variety of diseases and pose many threats to human health. In this study, 73 strains of Bacillus cereus were isolated and identified from six types of foods from seven different cities in a province, and the antibiotic-resistant phenotype was detected by using the Bauer-Kirby method. Results showed that the 73 isolates were completely sensitive to gentamicin and 100% resistant to chloramphenicol, in addition to which all strains showed varying degrees of resistance to 13 other common antibiotics, and a large number of strains resistant to multiple antibiotics were found. A bioinformatic analysis of the expression of resistance genes in Bacillus cereus showed three classes of antibiotic-resistant genes, which were three of the six classes of antibiotics identified according to the resistance phenotype. The presence of other classes of antibiotic-resistant genes was identified from genome-wide information. Antibiotic-resistant phenotypes were analyzed for correlations with genotype, and remarkable differences were found among the phenotypes. The spread of antibiotic-resistant strains is a serious public health problem that requires the long-term monitoring of antimicrobial resistance in Bacillus cereus, and the present study provides important information for monitoring antibiotic resistance in bacteria from different types of food.

Neolithic long-distance exchanges in Southern Arabia: A supposed road for the ‘Jade’ axes

This paper discusses the results of a new geo-archaeological study on the nephrite (jade) axes discovered in southern Oman (Dhofar Governorate). The research presents a first account of the geological composition and the morphological structure of such tools and it outlines a preliminary distribution network of jade axe-heads across Southern Arabia. After the discovery of the first analysed sample at Shaqat Jadailah SQJ-3, in the Rub’ al-Khali Desert (Dhofar), four other archaeological axe-adze samples collected from southern Oman, were analysed using micro-Raman Spectroscopy and Energy Dispersive X-Ray Fluorescence (ED-XRF). We compared the analysed samples to other nephrite axes collected in the first pioneering exploration of Gertrude Caton-Thompson (Yemen) and Wilfred Thesiger (South Oman). These objects were then correlated with nephrite raw material from the basement exposures in Yemen. Available data show that the raw material originating in Yemen reached the Neolithic groups of Southern Rub’ al-Khali and coastal Dhofar most likely during the 6th-5th millennium BC, following a similar path to the obsidian route. The colour, texture and composition, together with the presence of other classes of lithic artefacts such as the trihedral projectile points, indicate that during this period Southern Oman was fully integrated into long-distance exchange networks. The analysis of the collected samples show that they are made exclusively from nephrite, and not from other general “green stones”. Considering the high hardness and toughness of the nephrite, this fact allows the hypothesis of a deliberate choice in the selection of raw material for its durability or prestige value.

VALIDATION OF THE ENZYME-LINKED IMMUNOSORBENT ASSAY FOR EMIQUANTITATIVE DETERMINATION OF IgM ANTIBODIES AGAINST CHLAMYDIA TRACHOMATIS

The object of the following study is representation of the scientific and methodical foundation of the procedure of validation of means of serum in vitro diagnosis basing on the sample of ELISA for semiquantification of specific Chlamydia trachomatis IgM-antibodies. Validation characteristics (precision, diagnostic and analytic specificity, diagnostic sensitivity, relative linearity) were defined both at the beginning of the release of diagnostic set and the expiration date (as the element of stability study). The values of diagnostic sensitivity and specificity, defined via the in-process set of serums (20 positive and 50 negative) comprised 100%. The presence of other classes of Chlamydia antibodies in samples didn’t influence the results of ELISA for specific IgM antibodies. Linearity of the method was sufficient. The intra-assay variation of results is between 3.1% to 6.4%, and intra-assay precision was from 1.5% to 8.4%, staying acceptable (≤ 10%) both at the moment of release and during expiration date. The ELISA method is validated, and the diagnostic kit is regarded as stable during 1 year.

Respiratory Muscle Paralysis Associated With Colistin, Polymyxin B, and Muscle Relaxants Drugs: A Case Report.

Polymyxins B and E (colistin) exert a bactericidal effect on the gram-negative bacterial cell wall, causing permeability changes in the cytoplasmic membrane, leading to cell death. Their use was substantially decreased in clinical practice from the 1970s to 2000s due to their significant nephrotoxicity and neurotoxicity compared to the newly introduced antibiotics. The increasing prevalence of multidrug-resistant gram-negative bacteria infections in this century has led to an upsurge in the use of these “older” drugs. Respiratory paralysis caused by neuromuscular blockage associated with the use of polymyxin B and E was reported mostly in literature published in the 1960s to 1970s with a few reports after 2000. In addition, such a reaction might be enhanced by the presence of other classes of drugs. We report a case of polymyxin B and E–induced apnea in a patient receiving “muscle relaxants.”

Reciprocal inhibiting interactive mechanism between the estrogen receptor and aryl hydrocarbon receptor signaling pathways in goldfish (Carassius auratus) exposed to 17β-estradiol and benzo[a]pyrene

In the aquatic environment, both the estrogen receptor (ER) and aryl hydrocarbon receptor (AhR) responses are established biomarkers for assessing exposure to pollutants. These receptor responses can also be affected by the presence of other classes of pollutants and may result in misinterpretation of existing pollution. In this study, we investigated the interaction between ER–vitellogenin (VTG) and AhR–cytochrome P450 1A (CYP1A) signaling pathways in goldfish (Carassius auratus) after 10days exposure to pollutants. 17β-Estradiol (E2) and benzo[a]pyrene (BaP) were selected as the ER and AhR agonists, respectively. The messenger RNA (mRNA) expression of ER–VTG and AhR–CYP1A in liver was determined using quantitative real-time polymerase chain reaction (QRT–PCR). VTG, endogenous E2 and 7-ethoxyresorufin-O-deethylase (EROD) were also studied. Exposure to E2 and BaP alone significantly induced the gene expression of ERα–VTG and AhR2–CYP1A, respectively. Moreover, the obvious expression of related proteins was also observed. However, these inductions were significantly reduced after combined exposure to E2 and lower concentrations of BaP (20 and 50μg/L), indicative of a reciprocal inhibiting ER–AhR interaction. However, high concentrations (100μg/L) of BaP did not affect the E2-induced gene expression. Changes in VTG protein were in accordance with the expression of VTG mRNA, and more VTG protein was observed in liver than in serum. The induced endogenous E2 levels were suppressed by the presence of BaP. While the gene expression of CYP1A showed a concentration-dependent increase, EROD induction exhibited a bell-shaped concentration-response curve. Taken together, these results demonstrate a reciprocal inhibiting mode of ER–AhR interactions and may lead to a possible underestimation of actual exposure.

Cocktail effects on biomarker responses in fish

One of today's greatest challenges in environmental toxicology is to understand effects of mixture toxicity, commonly referred to as cocktail effects, in humans and in wildlife. Biomarker responses in fish are routinely used to assess exposure of anthropogenic chemicals in the aquatic environment. However, little is known about how cocktail effects affect these biomarker responses. For this reason, there is an obvious risk for misinterpretation of biomarker-data and this can have profound negative effects on stakeholder's decisions and actions, as well as on legislations and remediation-plans initiated in order to reduce exposure to certain chemicals. Besides, chemical safety-levels are traditionally based on experiences from lab-studies with single chemicals, which is unfortunate as a chemical can be more toxic when it is mixed with other chemicals, because of the cocktail effect. This review focuses on pharmacokinetic interactions between different classes of pollutants on detoxification mechanisms and how that affects two commonly used biomarkers in the aquatic environment: (1) induction of cytochrome P450 1A (CYP1A) that is mediated via activation of the arylhydrocarbon receptor (AhR), used to assess exposure to aromatic hydrocarbons; (2) induction of vitellogenin (VTG) that is mediated via activation of the estrogen receptor (ER), used to assess exposure to estrogenic chemicals. These responses can be either directly or indirectly affected by the presence of other classes of pollutants as a result of cocktail effects. For example, chemicals that inhibit the function of key metabolic enzymes and transporter pumps that are involved in elimination of AhR- and ER agonists, can result in bioaccumulation of aromatic hydrocarbons and estrogenic chemicals resulting in increased biomarker responses. This cocktail effect can lead to overestimation of the actual exposure pressure. On the contrary, induction of expression of key metabolic enzymes and transporter activities can result in increased elimination of AhR- and ER agonists that can lead to possible underestimation of the exposure. Another type of cocktail effect is inhibiting receptor cross-talk that may cause decreased biomarker responses that can also lead to underestimation of the actual exposure. To address the possible involvement of pharmacokinetic interactions including receptor cross-talks, we need to combine analyses on receptor signaling with studies on function of key biotransformation enzymes such as major catabolic CYP enzymes ( e.g. CYP1-4) as well as efflux pumps ( e.g. ATP-binding cassette transporter proteins). Besides, studies of inhibition of these enzymes and pumps activities pose a great potential to be used as future biomarkers as they are more clearly liked to adverse outcomes, compared to for example induction of CYP1A and VTG expression.

The biosynthetic incorporation of short-chain linear saturated fatty acids by Acholeplasma laidlawii B may suppress cell growth by perturbing membrane lipid polar headgroup distribution.

Acholeplasma laidlawii B cells made fatty acid auxotrophic by growth in the presence of the biotin-binding agent avidin grow increasingly poorly at 37 degrees C when supplemented with single exogenous linear saturated fatty acids of decreasing hydrocarbon chain length. Interestingly, this progressive decrease in growth yields with decreasing hydrocarbon chain length is not observed when cells are cultured in the presence of other classes of exogenous fatty acids. Moreover, normal growth is observed is other types of fatty acids with equivalent or shorter hydrocarbon chain lengths, indicating that poor growth in the presence of short-chain linear saturated fatty acids cannot be due to a decrease in membrane lipid bilayer thickness per se. To understand the molecular basis of such growth inhibition, we determined the growth yields, membrane lipid fatty acid and polar headgroups compositions, and phase state and fluidity of the membrane lipids in cells progressively biosynthetically enriched in tridecanoic acid (13:0) or dodecanoic acid (12:0). The growth of fatty acid auxotrophic A. laidlawii B cells grown in the presence of binary combinations of an exogenous fatty acid which supports normal growth on its own and 13:0 or 12:0 revealed that growth inhibition is not observed until 13:0 and 12:0 biosynthetic incorporation levels reach about 90 and 60 mol %, respectively, after which growth is markedly inhibited. Differential scanning calorimetric analyses of membranes from cells maximally enriched in 13:0 indicate that the lipid gel/liquid-crystalline phase transition temperature is unexpectedly high but that at the growth temperature of 37 degrees C, the membrane lipid bilayer is almost exclusively in the liquid-crystalline state but is certainly not excessively fluid. However, high levels of 13:0 incorporation produce a greatly elevated level of the high melting, reversed nonlamellar phase-preferring lipid component monoglucosyl diacylglycerol, and greatly reduced levels of all other membrane lipid components. This marked elevation of monoglucosyl diacylglycerol levels can be rationalized as a regulatory response which maintains the lamellar/nonlamellar phase-forming propensity of the total membrane lipid mixture relatively constant in the face of the biosynthetic incorporation of increasing quantities of short-chain saturated fatty acids, which favor the lamellar phase. However, this lipid biosynthetic response produces a marked decline in the levels of anionic phospholipid and phosphoglycolipid which are probably required to maintain the minimal negative surface charge density of the lipid bilayer, which we suggest is responsible for the observed growth inhibition. This work shows that the lipid biosynthetic regulatory mechanisms present in this organism may sometimes operate at cross purposes such that it is not possible to simultaneously optimize all of the biologically relevant physical properties of the membrane lipid bilayer.

Structural Insights into the Mode of Action of a Pure Antiestrogen

Background: Estrogens exert their effects on target tissues by binding to a nuclear transcription factor termed the estrogen receptor (ER). Previous structural studies have demonstrated that each class of ER ligand (agonist, partial agonist, and SERM antagonist) induces distinctive orientations in the receptor's carboxy-terminal transactivation helix. The conformation of this portion of the receptor determines whether ER can recruit and interact with the components of the transcriptional machinery, thereby facilitating target gene expression. Results: We have determined the structure of rat ERβ ligand binding domain (LBD) in complex with the pure antiestrogen ICI 164,384 at 2.3 Å resolution. The binding of this compound to the receptor completely abolishes the association between the transactivation helix (H12) and the rest of the LBD. The structure reveals that the terminal portion of ICI's bulky side chain substituent protrudes from the hormone binding pocket, binds along the coactivator recruitment site, and physically prevents H12 from adopting either its characteristic agonist or AF2 antagonist orientation. Conclusions: The binding mode adopted by the pure antiestrogen is similar to that seen for other ER antagonists. However, the size and resultant positioning of the ligand's side chain substituent produces a receptor conformation that is distinct from that adopted in the presence of other classes of ER ligands. The novel observation that binding of ICI results in the complete destabilization of H12 provides some indications as to a possible mechanism for pure receptor antagonism.

The activity of class I and II alcohol dehydrogenase isoenzymes in the sera of patients with liver tumours.

We have measured the activity of class I and II alcohol dehydrogenase isoenzymes in the sera of patients with liver tumours, using class-specific fluorogenic naphthaldehydes as substrates. The activity of the tested isoenzymes was unchanged in primary tumours and significantly increased (class I) in metastatic liver tumours. The total enzyme activity was also increased (3-fold) in this group of patients. The elevated activity of class I isoenzymes in secondary tumours seems to be caused by the enzyme released from primary cells originating in the other organs, but increased total enzyme activity measured with chromogenic substrates may be proof of the presence of other classes of isoenzymes. These results show that the elevated class I isoenzymes and total enzyme activity in the sera of patients with liver tumours may indicate the metastatic origin of these tumours.

Independent duplications of Bf and C3 complement genes in the zebrafish.

As part of an ongoing project aimed at the characterization of the MHC system in bony fishes, we have attempted to identify the class III region in the zebrafish (a teleost), a region that in higher vertebrates contains genes coding for complement proteins C2, Bf and C4. We obtained several genomic PAC clones by hybridization with a zebrafish Bf probe, previously identified in our laboratory, and searched these for the presence of other class III genes. We were able to obtain a second Bf-like gene, however, we were unable to detect any C2- or C4-like genes. By using highly degenerated primers, we extended our search to a hepatopancreas cDNA library and amplified from it clones corresponding to three different C3-like genes, and also the Bf genes, but not any C2- or C4-like genes. The zebrafish therefore contains two Bf and three C3 loci but apparently no C2 and C4 loci. Independent duplications of the Bf and C3 genes in bony fishes suggest that complement plays a prominent part in the immune response of this class of vertebrates.

Isolation and quantification of class 1 MHC gene mutants in mouse T cells by immunoselection with a magnetic cell sorter (MACS)

A method is described for determining the frequency of cells with a mutation in an autosomal gene coding for a membrane protein. Using a monoclonal antibody to H-2K k surface antigen and magnetic cell separation (MACS) more than 10 4-fold enrichment of the H-2K k negative population was achieved, as tested with artificial mixtures containing a known number of antigen-negative cells. After a second magnetic sorting mutant frequencies as low as 10 −6 could be measured. The number of clonogenic mutants was evaluated by limiting dilution cloning and verification of the mutant phenotype by FACScan (flow cytometry) analysis in a representative number of clones. The spontaneous frequency of H-2K k deficient mutants was 0.80 × 10 −6, and this increased after irradiation with 6 Gy X rays to 3.38 × 10 −6 within the next 8 weeks. About 50 mutant clones were screened for the presence of other class 1 antigens on the cell surface by FACScan analysis. All mutants continued to express other class 1 antigens.

Dissolved and particulate marine lipid classes: a review

There are similar lipid compounds present in the dissolved and particulate fractions of seawater, but the processes governing their concentrations in each fraction appear to be different. Although they are composed primarily of atoms of carbon and hydrogen, marine lipid compounds can be subdivided into as many as 16 individual classes according to their chemical structure. These classes are present in the dissolved and particulate fractions of seawater at the μgl −1 level. The compounds in most of these classes have known functions in various types of cells, or known anthropogenic sources. It is possible to distinguish energy storage clases, membrane classes, pollutants and indicators of lipid degradation. Individual classes or groups of certain classes may be used to indicate the presence of certain types of organisms as well as their physiological state and activity. The presence of other classes at the μgl −1 level can provide a signal of deteriorating water quality.