AcrB-TolC efflux system is essential for macrolide resistance in Helicobacter pylori

The prevalence of Helicobacter pylori strains resistant to macrolide is increasing worldwide. Macrolide molecules can be generally extruded by the AcrB-TolC system in bacteria. The H. pylori 26695 genome was assessed for putative translocases and the outer membrane efflux of AcrB (HP607) and TolC (HP605) proteins. We investigated the role of the AcrB-TolC efflux system in macrolide resistant (M-R) H. pylori. Both acrB- and tolC-mutant M-R strains were constructed from M-R strains by insertional inactivation of the acrB and tolC genes. The minimal inhibition concentrations (MICs) of erythromycin (EM) and clarithromycin (CLR) were determined by an agar dilution assay. To investigate the efflux ability of macrolides, intracellular accumulation of radiolabeled EM in the H. pylori 26695 strain, M-R strain, and acrB- and tolC-mutant M-R strains was measured by a liquid scintillation counter. For Post antibiotic effect (PAE), EM-treated H. pylori was diluted 1000-fold to remove antimicrobial activity. After additional 24 hours incubation, the CFU was measured. The decrease in the levels of resistance to EM and CLR was 32-fold higher for the acrB- and tolC-mutant M-R strains than the M-R strains. The intracellular EM concentration significantly increased in the acrB- and tolC-mutant M-R strains than the H. pylori 26695 and M-R strains. Diluted acrB, and tolC M-R mutant H. pylori after EM treatment was markedly reduced compared to M-R H. pylori. Our result showed that the M-R mechanism of H. pylori is significantly associated with AcrB-TolC efflux system.

Penentuan Komposisi Bahan Bakar Nabati Dalam Bahan Bakar Minyak Campuran Menggunakan Metode Direct Counting C-14

ABSTRAK. Telah dilakukan penentuan komposisi bahan bakar nabati (BBN) dalam bahan bakar minyak campuran (BBMC) dengan metode direct counting C-14. Penentuan komposisi BBN dalam BBMC dilakukan dengan cara memipet 10 mL BBMC ke dalam vial gelas kemudian ditambahkan 10 mL larutan sintilator Ultima Gold F (UGF) ke dalamnya. Vial tersebut dikocok agar campuran menjadi homogen kemudian dicacah menggunakan LSC (Liquid Scintillation Counter) Elmer Perkin 2900TR selama 20 menit sebanyak 30 siklus. Hasil pencacahan ditampilkan dalam bentuk tSIE (transformed external standard spectrum) dan cpm (cacahan permenit). Hasil analisis memperlihatkan nilai cpm yang meningkat seiring kenaikan persentase BBN dalam BBMC. Nilai cpm terendah dan tertinggi untuk sampel bensin, avtur, dan solar berturut-turut adalah 14,2363 dan 62,0343, 10,664 dan 44,535, serta 9,410 dan 61,789. Terdapat korelasi kuat antara nilai tSIE dan nilai cpm pada bensin dan solar tapi tidak pada avtur. Hasil analisis terhadap sampel uji menunjukkan bahwa sampel tersebut berada di luar grafik deret sampel. Metode direct counting ini diharapkan dapat menjadi referensi dalam uji mutu BBMC.ABSTRACT. The composition of biofuel (BF) in mixed oil fuel (MOF) has been determined using the C-14 direct counting method. Determination of the composition of BF in MOF was carried out by pipetting 10 mL of BBMC into a glass vial and then adding 10 mL of Ultima Gold F (UGF) scintillator solution into it. The vial was shaken so that the mixture became homogeneous and then counted using the Elmer Perkin 2900TR LSC (Liquid Scintillation Counter) for 20 minutes for 30 cycles. The results of the counting are displayed in the form of tSIE (transformed external standard spectrum) and cpm (counts per minute). The results of the analysis show that the value of cpm increases with the increase in the percentage of BF in MOF. The lowest and highest cpm values for gasoline, avtur, and diesel samples were 14.2363 and 62.0343, 10.664 and 44.535, and 9.410 and 61.789, respectively. There is a strong correlation between tSIE and cpm values for gasoline and diesel but not for avtur. The results of the analysis of the test sample indicate that the sample is outside the sample series graph. This direct counting method is expected to be a reference in the BBMC quality test.

Standardisation of 241Am activity for a key comparison

The JRC applied six measurement techniques to standardise the activity of an 241Am solution in the frame of the 2003 key comparison CCRI(II)-K2.Am-241. The methods used were alpha-particle counting at a defined small solid angle, high-efficiency particle and photon counting with a windowless 4π CsI(Tl) sandwich spectrometer, 4π alpha counting with a pressurised proportional counter, alpha-gamma coincidence counting and sum counting with a small pressurised proportional counter and a NaI(Tl) well detector, and 4π counting with a liquid scintillation counter. All results were consistent and an unusually low measurement uncertainty of 0.054% was achieved. An overview is presented of the outcome of the key comparison exercise, which demonstrates international equivalence.

Correlation of Tritium Concentration in Rainwater with Cosmic Rays: Preliminary Results

The Radiochronology Center has been established in 1999 as a member of the Horizontal Laboratories network of the University of Ioannina. Recently it has added to its activities the development of a tritium measurements laboratory as part of the Radiochronology Center. The laboratory is equipped with a super low level background liquid scintillation counter, which is capable to measure very low concentrations of tritium for applications in radioprotection, dating and hydrology.For the aims of the present continuing study rainwater samples are collected monthly. Each sample is distilled and then it is passed through an electrolysis process to increase the tritium concentration. Five mL of the enriched sample are mixed with 15 mL of a scintillation cocktail, specially designed for tritium measurements and its beta activity is measured for 200 min. The LLD of tritium in the samples is estimated 3 Bq/L or 27 TU.Our preliminary results show that, during the measuring period tritium concentration increased with time. The tritium values are correlated with the cosmic ray neutron flux data at ground level, available for Greece in the same period. The measured tritium concentrations in rainwater, which range from 36 ± 8 to 64 ± 8 TU, may be used for local hydrology studies.

Effect of epinephrine on the absorption of lidocaine following application to the oral mucosa in rats

Background We investigated the role of epinephrine in prolonging the localization of lidocaine on the oral mucosa and inhibiting its absorption in the blood of rats. Methods We used 7–8-week-old pathogen-free Wistar male rats (n = 128) for our study. We divided them into the control group administered with 14C-labeled lidocaine hydrochloride gel only and the study group administered with 14C-labeled lidocaine hydrochloride gel with epinephrine. The medications were administered in the palatal mucosa of the rats. The amount of mucosa, palatine bone, and serum lidocaine was measured by radioactivity using a liquid scintillation counter and was observed using autoradiograms. Results Initially, there was no significant difference in the lidocaine levels between the lidocaine and lidocaine with epinephrine groups in the palatal mucosa (751.9 ± 133.8 vs. 669.8 ± 101.6 ng/mg [2 min]). After 4 min, the values were significantly lower in the lidocaine with epinephrine group (1040.0 ± 142.8 vs. 701.2 ± 109.0 ng/mg [20 min]). After 40 min, the lidocaine level became significantly higher in the lidocaine with epinephrine group (586.8 ± 112.4 vs. 1131.3 ± 155.2 ng/mg [40 min]). Similar results were observed in the palatine bone and serum. Conclusion Epinephrine prolonged the localization of lidocaine applied to the mucosa and inhibited its absorption into the bloodstream of rats. Clinical studies are required to evaluate the use of epinephrine-containing topical anesthetics on the oral mucosa.

ASSESSMENT OF RADON CONCENTRATIONS IN WATER SOURCES FROM SABON GARI LOCAL GOVERNMENT AREA, KADUNA STATE, NIGERIA

Radon concentration in water is one of the major problems of radiation protection in recent years. This work assessed the radon concentration in water sources from Sabon Gari, local government area, Kaduna State. The water samples were collected and analyzed using Liquid scintillation counter (Tri-Carb-LSA1000). The overall mean radon concentration of the waters samples was found to be 14.9 BqL-1, which is higher than the maximum permissible limit of 11.1 BqL-1 by USEPA and the world average value of 10 BqL-1 by UNSCEAR and WHO. The overall Annual effective dose (AED) due to inhalation of radon is calculated to be 37.6 μSvy-1. This value is less than the permissible limit of 100 μSvy-1 set by WHO. Also, the overall AED due to ingestion is estimated as 109.0, 154.2, and 180.4 μSvy-1 respectively for both Adult, children and Infant, which is slightly higher than the WHO permissible limit of 100 μSvy-1 for adults and less than the permissible limit of 200 μSvy-1 for children. This result shows that the inhabitants of Sabon Gari local government are safe from any radiological health related effects that may result from the inhalation of radon gas. Also, both Children and Infant are safe from any immediate radiological health risk, but for Adults, consuming any of the water sources (Well, Borehole and Surface) over a prolong period of time is not completely safe and may result in radiological health hazard

Comparative Study of the Biochemical Response Behavior of Some Highly Toxic Minerals on Selenosis in Rats

Many researchers have studied the metabolism of toxics including selenium (Se) in biological medium in rats and defined some correlations between selenium and other minerals as arsenic (As), cadmium (Cd), mercury (Hg), and thallium (Tl). An investigation of the potential influences of As, Hg, Tl and Pb on Se metabolism, which can suggest new drugs to cope the poisonousness of Se. The current study also has looked into the potential use of As(III)/As(V) toxic in the treatment of essential mineral Se in the animals (as rats) based on sequestration of these toxic elements into biologically inert complexes, reflecting the enormous interest in this subject. The acute studies have been initially achieved by shaping the pulmonary and biliary excretions of the volatile Se in neonatal masculine Holtzman rats which were injected with selenite subcutaneously in the hind flank, then the volatile Se was trapped in 8N HNO3 and the radioselenate detected in a scintillation counter. The chronic cases were carried out with the nursing of rats with a purified diet of water-soluble vitamin mix, fat-soluble vitamin mix, saccharides, oil, and salts. One week after the basic diet, the rats taken Se have received diets containing 10 ppm of the element as sodium selenite (Na2SeO3) or selenate (Na2SeO4) added in the salts. The calorimeter was used to analyze Se in the frozen tissue specimens. As, Hg, and Tl were repressed the volatized Se excreted from the lungs. As has assisted the biliary excretion of Se and inhibited the chronic selenosis. Tl has increased the retention of Se in the liver and kidney, but, had no chronic effect on the amount of Se deposited in all the studied tissues. Similarly, Hg has increased the retention of Se but in the spleen and carcass of rats indicating to the high Se concentration in blood. Hg and Tl have inhibited the Se in urine. No effects of the doses rich in As, Hg, and Tl on the Se excretion in fecal. Even though, we suggest As as a possible medication to chronic selenosis.