Occurrence of antibiotics and antibiotic-resistant bacteria in the Lebanese polluted Litani River

Antibiotic contamination in polluted rivers is well recognized as an environmental and public health challenge. In this study, the occurrence, distribution, and ecological risk assessment of three commonly used antibiotics (amoxicillin, ciprofloxacin, and azithromycin) were assessed in the Litani River, the most important and highly polluted river in Lebanon. Physicochemical and microbiological water quality parameters including the antibiotic-resistant ones were in parallel determined in the same sites. Water samples from five sites stretching across the river upper basin were analyzed for the antibiotics under study using high-performance liquid chromatography, with both fluorometric and UV detectors post-extraction using a solid-phase method with a hydrophilic-lipophilic balance cartridges. The disc diffusion method and standardized water quality methods were used for antibiotic-resistant bacteria and water quality assessment, respectively. Amoxicillin and ciprofloxacin were found at concentrations of 250 ng/L and 107.2 ng/L, while azithromycin was not detected in any of the sites under study. Varying levels of antibiotic resistance were detected with the isolated Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) while the total coliforms showed resistance to multiple antibiotics. COD, TP, PO43-, TN, NO3-, NH4 + , E. coli, total coliform, P. aeruginosa, and Cd levels surpassed permissible levels. Correlation analysis with water quality parameters (COD, total phosphate, phosphate, total nitrogen, and cadmium) showed a significant positive correlation with ciprofloxacin (r > 0.5, p value < 0.05). Also, the resistant P. aeruginosa showed a significant positive correlation with cadmium (r > 0.5, p value < 0.05) while the resistant E. coli was positively correlated with total nitrogen, nitrate, and lead levels (r > 0.5, p value < 0.05). The ecological risk assessment revealed that all the tested antibiotics pose low risks (ecological risk quotient RQ < 0.1) except ciprofloxacin, which could pose a medium risk (0.1 < RQ < 1). Future research concerning the long-term assessment of antibiotics' residues and the identification of resistance genes in the river is recommended.

Assessing the Psychometric Properties of the Internet Addiction Test (IAT) Among Lebanese College Students

Internet addiction is an emergent problem; yet, both a strong conception of the factors precipitating challenging activities and a gold standard tool for evaluating symptoms are deficient. The aim of this study was to carry out a psychometric analysis using the most commonly employed screening tool, the young Internet Addiction Test (IAT), comprising a sample of Lebanese University medical students. Two hundred and fifty-six undergraduate medical students from a university in Beirut, Lebanon were included in our IAT. Exploratory factor analysis was employed, and four factors were extracted. These four factors were named as Lack of Control, Social Withdrawal and Emotional Conflict, Time Management Problems, and Concealing Problematic Behavior. Furthermore, the selected factors explained 56.5% of the total variance. Cronbach's alpha coefficient for the internal reliability of the scale was found to be 0.91. For each subscale, the internal consistency score was approximated and detected as 0.76, 0.74, 0.69, and 0.63 for the first through fourth factor, respectively. Item total correlations were calculated and had a value range from 0.37 to 0.63 for the 20 items. IAT is a proper tool for evaluating internet addiction in Lebanese college students.

Seasonal variations of solar UVB and UVA in Syria

Seasonal variations of solar UVB (285-320 nm) and UVA (320-400 nm) were measured in three sites in Syria (33-37 N degrees) for 2 y: 1992-1993. UVB measurements were performed using polysulphone films and Robertson-Berger meters, while UVA measurements were done by a UVA intensity meter. Two sets of measurements were carried out: 1) Maximal daily doses 3 times per week (every other day); and 2) Diurnal variations from sunrise to sunset, every 1 h, twice per month (every fortnight).

Action spectra and chromophores for lethal photosensitization of Candida albicans by DNA monoadducts formed by 8-methoxypsoralen and monofunctional furocoumarins

The red-shift of furocoumarin action spectra, compared with their absorption spectra, has been investigated. An action spectrum for 8-methoxypsoralen (8-MOP) monoadduct formation in the yeast Candida albicans has been determined. The yeast cells were initially exposed to sublethal doses of monochromatic UVA at different wavelengths. Monoadduct formation was monitored by growth inhibition induced, after washing out any unbound 8-MOP, by re-irradiation with a constant second (non-lethal) dose of 330 nm radiation. A comparison between this action spectrum and the absorption spectrum of the dark complex of 8-MOP and DNA was made. In addition, the action spectra of monoadduct formation of five monofunctional compounds including a coumarin derivative have been determined. These action spectra were compared with their respective DNA dark complex absorption spectra. In general, the peaks of the furocoumarin DNA dark complexes show a red-shift when compared with the free furocoumarin molecule and the action spectra show peaks which correspond with the peaks of the dark complexes. Such data indicate that the DNA dark complex is the chromophore for growth inhibition in yeast rather than the free furocoumarin. The similarity of the 8-MOP monoadduct formation action spectrum and 8-MOP action spectra suggests that spectral dependence for the photobiological effects (including the red-shift) is dependent on monoadduct formation rather than, as previously suggested by several authors, crosslink formation. The action spectrum for the coumarin derivative 4-methyl N-ethylpyrrolo (3,2-g) coumarin (PCNEt) correlated well with the free molecule absorption spectrum rather than DNA dark complex indicating that the free molecule is the chromophore.(ABSTRACT TRUNCATED AT 250 WORDS)