ArfA recognizes the lack of mRNA in the mRNA channel after RF2 binding for ribosome rescue

Although trans-translation mediated by tmRNA-SmpB has long been known as the sole system to relieve bacterial stalled ribosomes, ArfA has recently been identified as an alternative factor for ribosome rescue in Escherichia coli. This process requires hydrolysis of nascent peptidyl-tRNA by RF2, which usually acts as a stop codon-specific peptide release factor. It poses a fascinating question of how ArfA and RF2 recognize and rescue the stalled ribosome. Here, we mapped the location of ArfA in the stalled ribosome by directed hydroxyl radical probing. It revealed an ArfA-binding site around the neck region of the 30S subunit in which the N- and C-terminal regions of ArfA are close to the decoding center and the mRNA entry channel, respectively. ArfA and RF2 sequentially enter the ribosome stalled in either the middle or 3′ end of mRNA, whereas RF2 induces a productive conformational change of ArfA only when ribosome is stalled at the 3′ end of mRNA. On the basis of these results, we propose that ArfA functions as the sensor to recognize the target ribosome after RF2 binding.     

Curcumin Ameliorates Streptozotocin‐Induced Heart Injury in Rats

Heart failure (HF) is one of diabetic complications. This work was designed to investigate the possible modulatory effect of curcumin against streptozotocin‐induced diabetes and consequently HF in rats. Rats were divided into control, vehicle‐treated, curcumin‐treated, diabetic‐untreated, diabetic curcumin–treated, and diabetic glibenclamide–treated groups. Animal treatment was started 5 days after induction of diabetes and extended for 6 weeks. Diabetic rats showed significant increase in serum glucose, triglycerides, total cholesterol, low‐density lipoprotein‐cholesterol, very low density lipoprotein‐cholesterol, nitric oxide, lactate dehydrogenase, cardiac malondialdehyde, plasma levels of interleukin‐6, and tumor necrosis factor‐alpha, and also showed marked decrease in serum high‐density lipoprotein‐cholesterol, cardiac reduced glutathione, and cardiac antioxidant enzymes (catalase, superoxide dismutase, and glutathione‐S‐transferase). However, curcumin or glibenclamide treatment significantly mitigated such changes. In conclusion, curcumin has a beneficial therapeutic effect in diabetes‐induced HF, an effect that might be attributable to its antioxidant and suppressive activity on cytokines.     

Larvicidal and adulticidal activity of essential oils from plants of the Lamiaceae family against the West Nile virus vector,Culex pipiens (Diptera: Culicidae)

Culex pipiens mosquitoes are the most widely distributed primary vector of the West Nile virus worldwide. Many attempts for investigation of botanical pesticides to avoid the development of pesticide resistance to conventional synthetic pesticides that are recognized as a threat to the diversity of ecosystems. The study aimed to determine the components of three essential oils of Lamiaceae family, lavender (Lavandula angustifolia), peppermint (Mentha piperita L.), and rosemary (Rosmarinus officinalis L.) by gas chromatography-mass spectrometry (GC–MS) analysis. Furthermore, aimed to validate the insecticidal activities of these oils as larvicidal agents against the third instar larvae of Culex pipiens using five different concentrations (62.5, 125, 250, 500, and 1000 ppm) for each oil in five replicates and as an adulticidal agent against approximately three-day-old female adults of Cx. Pipiens using 0.5, 1, 2, 4, and 5% concentrations in three replicates. The results generally showed a dose-related response. At 1000 ppm, rosemary oil showed the highest larvicidal (100%) (LC₅₀, 214.97 ppm), followed by peppermint oil (92.00% mortality and LC₅₀ (269.35 ppm). Lavender oil showed the lowest efficacy with 87.20% mortality and LC₅₀ (301.11 ppm). At 5% oil concentration, the highest knockdown rate at 1 h was recorded for lavender oil (95.55%), followed by peppermint oil (88.89%) and lastly rosemary oil (84.44%). After 24 h, rosemary oil showed the lowest adult mortality rate (88.89%; LC₅₀, 1.44%), while lavender and peppermint oils both showed a 100% mortality rate, with (LC₅₀, 0.81% and 0.91%, respectively). The chemical constituents of the oils consisted of monoterpenes and sesquiterpenes that determined their insecticidal activities against the target insect stage. The study proposed that rosemary essential oil may be useful for the control of Cx. pipiens larvae as part of an integrated water treatment strategy, and lavender and peppermint oils may be used in an integrated plan for adult’s control.     

Natural killer cells in human colostrum

The presence of natural killer cells in human colostrum was disclosed with the use of a fluorochrome-labeled monoclonal antibody HNK-1 (Leu-7) that recognizes cells with natural killer and killer activity. Approximately 0.5% of total colostral cells were stained with this reagent. These cells were separated by the fluorescence-activated cell sorter and examined for their morphology by electron microscopy and for their cytotoxic activity against 51Cr-labeled K562 target cells. Two morphological types of natural killer cells were observed in colostrum: the first was represented by large cells with numerous vacuoles but without dense cytoplasmic granules; the second type, which occurred with lower frequency, resembled the large granular lymphocytes associated with natural killer activity in peripheral blood. The HNK-1-positive cells from colostrum displayed low cytotoxic activity against K562 target cells. Incubation of HNK-1-positive cells from peripheral blood with cell-free colostrum resulted in a dose-dependent inhibition of the cytotoxic activity. The functional changes were accompanied by morphological alterations which included degranulation and the formation of numerous vacuoles. The variances in the cytotoxic activity of peripheral blood HNK-1-positive cells suspended in different dilutions of colostrum suggest that this fluid contains humoral factors which modify morphology and function depending on their concentrations.     

Influence of follicular maturation on luteinizing hormone-, cyclic 3',5'-adenosine monophosphate-, forskolin- and cholesterol-stimulated progesterone production in hen granulosa cells

The influence of follicular maturation on progesterone production by collagenase-dispersed hen granulosa cells was measured in short-term incubations. Granulosa cells of the largest follicle (F1) produced up to ten times more progesterone than cells from smaller follicles (F3-F5), not only in response to luteinizing hormone (LH), but also when stimulated by exogenous cyclic AMP or forskolin, both of which raise intracellular cyclic AMP levels by nonreceptor-mediated mechanisms. Moreover, when granulosa cell progesterone synthesis was stimulated by incorporating 25-hydroxy-cholesterol into the incubation medium, an identical pattern was obtained. This could be attributed to a corresponding increase in the specific activity of the mitochondrial cholesterol side-chain cleavage enzyme (20,22 desmolase). An increase in the apparent Vmax was observed without a change in the apparent Km values. Pregnenolone substrate at concentrations which raised progesterone production to levels similar to those observed in response to LH stimulation was utilized equally by granulosa cells of mature and developing follicles. However, at high pregnenolone concentrations, granulosa cells of mature follicles converted significantly more of the precursor to progesterone. Assay of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) showed that the enzyme has two Kms: a low Km present in cells of both mature and developing follicles, and a high Km found only in granulosa cells of more mature follicles. It is concluded that LH-promoted progesterone synthesis in granulosa cells of developing chicken follicles is restricted not so much by the availability of receptors and the competence of the adenylate cyclase/cyclic AMP system, but by the activity of key enzymes, principally the cholesterol-20,22 desmolase.     

Selective activation of extrathymic T cells in the liver by glycyrrhizin

Extrathymic pathways for T cell differentiation were recently demonstrated in the liver, intestine and omentum. In this study, glycyrrhizin (GL), a plant extract was investigated as to its effect on extrathymic T cells in the liver of mice. A new method using anti-LFA-1 mAb in conjunction with anti-TCR or -CD3 mAbs to sensitively identify such extrathymic T cells is included. Single injection and repeated injections of GL increased not only the number of total hepatic MNC but also the proportion of intermediate TCR cells, which are extrathymic T cells uniquely seen in the liver. In contrast to other tested reagents (e.g., lymphotoxin and estrogen) that activated the extrathymic T cells and simultaneously induced profound thymic atrophy, GL did not affect regular T cells in the thymus. The present results suggest that the selective activation of extrathymic T cells in the liver might be intimately related to the clinical effects of GL.     

Schistosoma mansoni: angiotensin converting enzyme activity in mice under the influence of praziquantel and/or captopril.

Murine schistosomiasis is usually associated with hepatic granulomatous lesions together with high serum and granuloma angiotensin converting enzyme (ACE) activity. Praziquantel (PRZ) which is known to reduce granuloma size was studied to show whether this effect is related to changes in ACE activity. Furthermore, captopril was studied to show whether by inhibiting ACE activity, the drug could also affect granuloma size. PRZ, captopril, and their combination led to significant reduction in liver granuloma. However, in normal mice, captopril was shown to increase rather than decrease serum ACE. The decrease in ACE activity by PRZ was correlated with its curative effect in infected mice. However, in experimentally induced pulmonary granulomata, the drug reduced granuloma size without affecting ACE activity of either serum or granuloma. It may be concluded that reduction in ACE activity may be beneficial as far as diminution of granuloma size is concerned and irrespective of whether there is an active infection or not. The possible use of Captopril as an antihypertensive in bilharzial infections associated with hypertension would probably not adversely affect the granulomatous lesions.     

Spectroscopic determination of succinylcholine in dosage forms using eosin Y

Two simple and sensitive analytical assay methods using spectrophotometry and spectrofluorimetry techniques were developed for the estimation of succinylcholine chloride (SUC) in pharmaceutical preparations. The suggested methods are based on the formation of an ion pair complex formed between the drug and eosin Y spectrophotometrically (Method I), or the suppressive effect of succinylcholine on the native fluorescence property of eosin Y (Method II). The spectrophotometric method (Method I) involves measuring the absorbance of the complex between succinylcholine and eosin Y at 550 nm in Britton Robinson buffer of pH 3. However, the spectrofluorimetric method (Method II) involves measuring the quenching effect of the studied drug on the native fluorescence property of eosin Y at the same pH at 550 nm after excitation at 480 nm. The absorbance versus concentration of the drug is rectilinear over the range of 0.5 to 15 μg/ml. The formation constant was 3.5 × 10⁴ and the Gibb's free energy change was ?2.5 × 10⁴ J/mol. In Method II, the relative fluorescence intensity was directly proportional to SUC concentration over the range of 0.05 to 1 μg/ml. The proposed methods allowed a successful application to the estimation of succinylcholine ampoules. An explanation of the reaction pathway was postulated.     

Down-regulation of circulating microRNA let-7a in Egyptian smokers

Altered miRNAs were associated with cigarette smoking. The study aimed to examine the gene expression level of plasma let-7a among healthy smokers and compared it with the non-smokers. Forty subjects were recruited for the present study and classified into 21 smokers and 19 non-smokers, age, and sex were matched. The software that used to design functional primers was MIRprimer. Quantitative real-time PCR was employed to compare the relative expression of plasma let-7a. Results showed that the level of let-7a was down-regulated in smokers to 0.34fold (p?=?0.006) that of the non-smokers. Plasma let-7a showed an area under curve (AUC) of 0.749 with sensitivity 43% and specificity 100%. In conclusion, plasma let-7a was significantly down-regulated in the smokers, and it might be considered a candidate biomarker to discriminate between smokers and non-smokers.