Bioaccumulation of heavy metals Cu, Zn, and Hg in muscles and liver of the stellate sturgeon (Acipenser stellatus) in the Caspian Sea and their correlation with growth parameters

Bioaccumulation of Cu, Zn, Hg in muscles and liver tissues of stellate sturgeon (Acipenser stellatus) from the southern Caspian Sea was measured. Effects of condition factor (CF), age and hepatosomatic index (HSI) on metal accumulation were also determined. Some 40 stellate sturgeons were collected using gill nets in winter and spring 2007-2008 from the southern shores of the Caspian Sea. Total (TL) and fork (FL) length and weight of all specimens were measured. Cross sections of first ray of pectoral fins were used for age determination. Muscle and liver samples were taken and transported to the laboratory in ice packs and kept in -20 °C prior to analyses. In the laboratory samples were oven dried, digested with HClO3 and HNO3 and diluted with dionized water to 50cc to measure Cu, Zn, and Hg concentration with a flame spectrophotometer. Sequence of metals in Acipenser stellatus was Zn>Hg> Cu in muscle tissues and Zn>Cu>Hg in liver samples. Concentration of Zn was slightly in correlation with age (R= 0.3). A negative correlation was observed between Zn concentrations with condition factor (R = -0.3). Zn concentrations were negatively correlated in muscle tissues (R = -0.3). The results were compared to international standards proposed by MAAF, EEC and NHMRC. Our study showed that accumulation of heavy metals in sturgeon tissues was influenced by concentration of metals in sediment and the physiological state of fish

Concentration of heavy and toxic metals Cu, Zn, Cd, Pb and Hg in liver and muscles of Rutilus frisii kutum during spawning season with respect to growth parameters

Concentration of heavy and toxic metals Cu, Zn, Cd, Pb and Hg were determined in liver and muscles of Rutilus frisii kutum and their relationships with growth parameters (length, age, condition factor) and hepatosomatic index were examined. Thirty-six fish samples were collected from February through March 2009 caught by beach seine in the southwest parts of the Caspian Sea. Atomic absorption and Hg determined concentrations of Cd, Pb, Zn and Cu by vapor method. Cadmium was recorded only in liver samples. Range of other metals in muscle tissue were ND-0.591, 0.001-0.013, 11-26 and 0.729-7.261 µg/g dw for Pb, Hg, Zn and Cu respectively. Highest levels of Pb, Zn, and Cu were recorded in muscles Hg and Cd in liver samples. Growth parameters showed a significant relationship with Zn and Cd concentrations in liver samples and only Zn concentrations in muscle samples. There was a positive significant correlation between concentration of Cd in liver and physiological indices (p<0.05). Although higher concentration of Pb was recorded in this study in comparison to previous studies, based on Provisional Tolerable Weekly and daily Intake of fish for human health, kutum is considered safe for human consumption. Considering the results of this study it seems reproductive status of the fish influences heavy metals concentration in liver and muscles of kutum and therefore concentrations of some metals such as Zn and Cu in liver samples may not be a reliable bioindicator for environmental pollution

Changes in biochemical and physiological responses of common carp, Cyprinus carpio L. after long-term exposure to Pb (II)

In this study, the chronic toxic effects of Pb (II) on common carp, Cyprius carpio were investigated using several biomarkers at different levels of biological functions for assessing changes in ecosystem quality. In a bioassay,common carp juveniles were individually exposed to different dose of heavy metal, Pb II (0, 0.45, 0.89, 1.34 mg.l-1) for 28 days. Morphological indices such as hepatosomatic index, condition factor and lipid peroxidation (LPO) level and also the activities of superoxide dismutase (SOD) and catalase (CAT) were measured. These results indicated that there was significant lower condition factor in fish exposed to the highest concentration of Pb (p<0.05). The activity of hepatic antioxidant enzymes (SOD & CAT) and LPO level was significantly elevated after long-term exposure to higher concentration of Pb (p<0.05). Briefly, our findings suggested that common carp exposed to lead, develop oxidative stress, hence long-term exposure to higher concentrations of Pb could seriously affect the health status of fish

Vibration analysis of a small diesel engine using diesel-biodiesel fuel blends

Biodiesel as an environmentally friendly fuel has the potential to provide comparable engine performance results.  Biodiesel is a renewable fuel produced from vegetable and seed oils, animal fats or waste edible oils.  Sound and vibration caused by the combustion process in the engine might have direct effects on users.   One of the important characteristics of diesel fuels is high noise and vibration.  The present study was carried out to examine the vibration of different diesel-biodiesel fuel blends in power tiller engine.  The main goal was to present fuels with the minimum vibration.  So, the time domain signals were analyzed in five levels of engine speed, three axes and six fuel blends on the engine.  The signal processing and statistical approach were applied for data analysis.  The results showed that in all engine speeds, the dominant frequency is matched to the piston stroke frequency of the engine, as well as the frequency of vibration with the increase of engine speed.  The experiments indicated that the magnitude of vibration in the power tiller engine depends on the axis of measurement, engine speed and the fuel blends.  Vibration acceleration is significantly affected by engine speed and the increase in forward speed due to the increase in vibration acceleration rms.  The results of the experiments revealed that vibration acceleration is significantly affected by the axis of measurement.  The magnitude of vibration acceleration in vertical axis was more than that in the other two axes and magnitude of vibration acceleration in the longitudinal axis was more than that in the lateral axis.  Fuel blends had significant effect on the vibration.  It demonstrated that B100, B5 and B20 have the lowest vibration.  On the contrary, B15 and B10 have the highest vibration.   Keywords: vibration analysis, power tiller, time domain, frequency domain, diesel-biodiesel fuel blend

Prevalence of drug-resistant Klebsiella pneumoniae in Iran: A review article

Background: The infections caused by drug resistant strains of Klebsiella pneumoniae are becoming an important health problem worldwide. There are several reports on antimicrobial resistant status of K. pneumoniae in Iran. However, a comprehensive analysis on drug-resistant K. pneumoniae from different parts of Iran has not yet been performed. Methods: The searches were done according to several English and Persian databases including PubMed, Scopus, Iranmedex, and SID to identify studies addressing antibiotic resistant K. pneumoniae in Iran from Jan 1998 to Nov 2014. Comprehensive Meta-Analysis (V2.2, Biostat) software was used to analyze the data. Results: The incidence rate of imipenem and ceftazidime resistance in K. pneumoniae isolates was 3.2 (95 confidence interval CI, 1.5-6.5) and 55.7% (95% CI, 46.9-64.1), respectively. The highest rate of resistance in isolates of K. pneumoniae was seen against ampicillin (82.2%), aztreonam (55.4%) and nitrofurantoin (54.5%). Conclusion: There is a relatively high prevalence of drug resistant K. pneumoniae isolates in Iran. Thus, a high degree of awareness among physicians and microbiologists, active infection control committee, appropriate antimicrobial therapy, improvement of hygiene condition and monitoring of drug resistant isolates are urgently needed in order to better control the emergence and spread of drug-resistant K. pneumoniae isolates in hospital settings. © 2018, Iranian Journal of Public Health. All rights reserved

Molecular characterization of the pilS2 gene and its association with the frequency of pseudomonas aeruginosa plasmid pKLC102 and PAPI-1 pathogenicity island

Introduction: Pseudomonas aeruginosa is the most common opportunistic pathogen associated with a broad range of infections, including cystic fibrosis, ocular, otitis media, and burn infections. The aim of this study was to show the frequency of the pilS2 gene, and its association with P. aeruginosa plasmid pKLC102 and PAPI-1 pathogenicity island among P. aeruginosa strains. Methods: The samples were collected from patients with cystic fibrosis, ocular, otitis media, and burn infections between January 2016 and November 2017. DNA was extracted using the DNA extraction kit and was used for PCR assay. PCR with 4 primer-pairs including 976 F/PAPI-1R, 4542 F/intF, SojR/4541 F, and intF/sojR was performed to identify PAPI-1. pKLC102 was detected using three other primer-pairs including cp10F/ cp10R, cp44F/cp44R, and cp97F/cp97R. Results: A total of 112 P. aeruginosa isolates were collected from patients with cystic fibrosis (36), burn (20), otitis media (26), and ocular (30) infections. The results of PCR showed that pilS2 gene was identified in 96 (85) strains. PAPI-1�attB integration was detected among 38 (33.9) isolates and the circular form of PAPI-1 detected among 17 (14) isolates. In addition, 79 (70.5) strains were found to be positive for pKLC102. Conclusion: We found that the majority of the isolates may be susceptible to transfer this significant island and the related element pKLC102 into recipient isolates lacking the island owing to high association of the PilS2 pilus with the islands in the studied strains. It is anticipated that strains isolated from burn and eye with the highest rate of PilS2, PAPI-1, and pKLC102 association have a high level of antibiotic resistance. © 2019 Bahramian et al

Distribution system protection by coordinated fault current limiters

The protection of distribution networks is one of the most substantial issues, which needs special attention. Using appropriate protective equipment enhances the safety of the power distribution network during the fault conditions. Fault current limiter (FCL) is a kind of modern preserving system being used for protecting power networks and equipment. One of the main concerns of power networks is the voltage restoration of buses during faulty conditions. In this study, a group of coordinated DC reactor type faults current limiters are designed and tested to protect the network and restore its buses voltage within the fault period. To coordinate FCLs and measurement devices during the fault sequences, a wireless communication system and decision-making computer are used. The proposed FCLs coordination strategy is modelled and simulated in MATLAB platform and the results are validated by the developed laboratory test setu

Folding Circular Permutants of IL-1β: Route Selection Driven by Functional Frustration

Interleukin-1β (IL-1β) is the cytokine crucial to inflammatory and immune response. Two dominant routes are populated in the folding to native structure. These distinct routes are a result of the competition between early packing of the functional loops versus closure of the β-barrel to achieve efficient folding and have been observed both experimentally and computationally. Kinetic experiments on the WT protein established that the dominant route is characterized by early packing of geometrically frustrated functional loops. However, deletion of one of the functional loops, the β-bulge, switches the dominant route to an alternative, yet, as accessible, route, where the termini necessary for barrel closure form first. Here, we explore the effect of circular permutation of the WT sequence on the observed folding landscape with a combination of kinetic and thermodynamic experiments. Our experiments show that while the rate of formation of permutant protein is always slower than that observed for the WT sequence, the region of initial nucleation for all permutants is similar to that observed for the WT protein and occurs within a similar timescale. That is, even permutants with significant sequence rearrangement in which the functional-nucleus is placed at opposing ends of the polypeptide chain, fold by the dominant WT “functional loop-packing route”, despite the entropic cost of having to fold the N- and C- termini early. Taken together, our results indicate that the early packing of the functional loops dominates the folding landscape in active proteins, and, despite the entropic penalty of coalescing the termini early, these proteins will populate an entropically unfavorable route in order to conserve function. More generally, circular permutation can elucidate the influence of local energetic stabilization of functional regions within a protein, where topological complexity creates a mismatch between energetics and topology in active proteins

A review on mechanism of action, resistance, synergism, and clinical implications of mupirocin against Staphylococcus aureus

Mupirocin (MUP), bactroban, or pseudomonic acid is a natural crotonic acid derivative drug extracted from Pseudomonas fluorescens which is produced by modular polyketide synthases. This antibiotic has a unique chemical structure and mechanism of action. It is a mixture of A�D pseudomonic acids and inhibits protein synthesis through binding to bacterial isoleucyl-tRNA synthetase. MUP is often prescribed to prevent skin and soft tissue infections caused by S. aureus isolates and where the MRSA isolates are epidemic, MUP may be used as a choice drug for nasal decolonization. It is also used for prevention of recurring infections and control the outbreaks. The emergence of MUP resistance has been increasing particularly among methicillin-resistant Staphylococcus aureus (MRSA) isolates in many parts of the world and such resistance is often related with MUP widespread uses. Although both low-level and high-level MUP resistance were reported among MRSA isolates, the rate of resistance is different in various geographic areas. In this review, we will report the global prevalence of MUP resistance, discuss synergism and mechanism of action of MUP, and provide new insights into the clinical use of this antibiotic. © 2018 Elsevier Masson SA