Biological transformation,kinetics and dose-response assessments of bound musk ketone hemoglobin adducts in rainbow trout as biomarkers of environmental exposure

Low levels (ng/g) of musk ketone (MK),used as a fragrance additive in the formulation of personal care products,are frequently detected in the water and other environment.Thus,aquatic organisms can be continuously exposed to MK.In this study,kinetics and dose-response assessments of 2-amino-MK (AMK) metabolite,bound to cysteine-hemoglobin (Hb) in rainbow trout,formed by enzymatic nitro-reduction of MK have been demonstrated.Trout were exposed to a single exposure of 0.010,0.030,0.10,and 0.30 mg MK/g fish.Tw...

Establishing a Multifaceted Comprehensive Maternity Cohort Facilitates Understanding of How Environmental Exposures Impact Perinatal Health

China’s“three-child policy”,implemented in response to population aging,has made the protection of maternal and infant health an urgent priority.In this environmental and medical big-data era,the Zhejiang Environmental and Birth Health Research Alliance(ZEBRA)maternity cohort was established with the aim of identifying risk factors for perinatal morbidity and mortality from the perspectives of both observational epidemiology and experimental etiology.Compared with conventional birth cohorts,the inclusion of a maternity cohort allows greater scope for research and places an emphasis on maternal health.In particular,it allows us to focus on pregnant women with a history of pregnancy-related illnesses and those planning to have a second or third child.There are currently many pressing issues in perinatal health,including the risk associations between exogenous together with endogenous factors and the occurrence of perinatal abnormalities,pregnancy complications,and adverse pregnancy outcomes.It is crucial to explore the interaction between environmental exposures and genetic factors affecting perinatal health if we are to improve it.It is also worthwhile to assess the feasibility of the early stage prediction of major perinatal abnormalities.We hope to study this in the ZEBRA cohort and also seek nationwide and international collaborations to establish a multicenter cohort consortium,with the ultimate goal of contributing epidemiological evidence to literature and providing evidence-based insights for global maternal and child healthcare.

Maternal Thyroid Hormones as Mediators between Phthalate Exposure and Neonatal Birth Weight:A Cross-Sectional Study from the Zunyi Birth Cohort

Studies have shown that exposure to phthalates can affect neonatal birth weight.However,epidemiological evidence on the mediating role of maternal thyroid hormones is limited.Therefore,this study,based on the Compliance Birth Cohort,aimed to reveal the potential mediating function of maternal thyroid hormones during pregnancy between phthalic acid ester(PAE)exposure and neonatal birth weight.The study included 1274 mother−infant pairs.Linear regression analysis revealed a negative association between MIBP and neonatal birth weight(β=−62.236;95%CI:−118.842,−5.631).Bayesian kernel-machine regression(BKMR)indicated a nonlinear negative association between PAE metabolites(PAEs)and birth weight.Linear regression analysis revealed a positive association between neonatal birth weight and FT3(β=41.605;95%CI:2.631,80.380).The BKMR model also found a positive association between thyroid hormones and birth weight but in a nonlinear manner.Additionally,linear regression analyses showed that TSH,TT3,TT4,FT3,and FT4 were associated with PAEs.The BKMR model revealed an inverted U-shaped association of PAEs with TT3 and FT3 and a nonlinear association with TSH,TT4,and FT4.Structural equation modeling revealed that MMP,MIBP,MBP,MEHP,MOP,MBZP,and MEOHP contributed to a net reduction in neonatal birth weight of 32 g through the TT3,FT3,TT4,and FT4 pathways.The findings suggest that exposure to PAEs during pregnancy leads to a reduction in neonatal birth weight,possibly due to the involvement of maternal thyroid hormones as mediators.Controlling maternal thyroid hormone levels during pregnancy may be a viable method to reduce the harmful effects of phthalate exposure on the developing fetus.

Daily exposure to low concentrations Tetrabromobisphenol A interferes with the thyroid hormone pathway in HepG2 cells

Tetrabromobisphenol A(TBBPA)is a flame retardant that adversely affects the environment and human health.The present study exposed HepG2 cells to low concentrations of TBBPA daily to investigate the changes in gene regulation,mainly related to pathways associated with the endocrine system.The quantitative polymerase chain reaction(qPCR)confirmed that prolonged exposure gradually activated the thyroid hormone and parathyroid hormone signaling pathways.The expression levels of genes related to the thyroid hormone signaling pathway were upregulated(1.15-8.54 times)after five generations of exposure to 1 and 81 nM TBBPA.Furthermore,co-exposure to 81 nM TBBPA and 0.5 nM thyroid hormone receptor antagonist for five generations significantly reduced the expression of thyroid hormone and parathyroid hormone receptors.Meanwhile,81 nM TBBPA inhibited the activation of the Ras pathway and downregulated Ras gene expression level(3.7 times),indicating the association between the toxic effect and thyroid hormone receptors.Additionally,our experiments revealed that the thyroid hormone pathway regulated the induction of the Ras signaling pathway by TBBPA.The study thus proves that daily exposure to TBBPA interferes with the thyroid hormone signaling pathway and subsequently the endocrine system.

The exposure risks associated with pathogens and antibiotic resistance genes in bioaerosol from municipal landfill and surrounding area

Pathogenic microbes with antibiotic resistance can thrive on municipal solid waste as nutrients and be aerosolized and transported to vicinities during waste disposal processes.However,the characterization of pathogenic bioaerosols and assessment of their exposure risks are lacking.Herein,particle size,concentration,activity,antibiotic resistance,and pathogenicity of airborne microorganisms were assessed in different sectors of a typical landfill.Results showed that active sector in downwind direction has the highest bioaerosol level(1234 CFU/m3),while residential area has the highest activity(14.82 mg/L).Botanical deodorizer from mist cannon can effectively remove bioaerosol.Most bioaerosols can be inhaled into respiratory system till bronchi with sizes ranging from 2.1−3.3 and 3.3−4.7μm.Pathogenic bacteria(Bacilli,Bacillus,and Burkholderia-Paraburkholderia)and allergenic fungi(Aspergillus,Cladosporium,and Curvularia)prevailed in landfill.Although high abundance of microbial volatile organic compounds(mVOCs)producing bioaerosols were detected,these mVOCs contributed little to odor issues in landfill.Notably,surrounding areas have higher levels of antibiotic-resistance genes(ARGs)than inner landfill with tetC,acrB,acrF,mdtF,and bacA as dominant ones.Most ARGs were significantly correlated with bacterial community,while environmental parameters mainly influenced fungal prevalence.These findings can assist in reducing and preventing respiratory allergy or infection risks in occupational environments relating to waste management.

Associations of Adolescence Exposure to Industrial Air Pollution with Cancer in Young Adults

There is substantial public concern about the health risks of proximity to petrochemical industries.In the Haifa Bay Area(HBA),which contains Israel’s densest industrial area,these concerns have been strengthened by elevated cancer mortality rates since the late 1960s.We studied the association between adolescent exposure to industrial air pollution in the HBA and adult-onset cancer.This is a historical cohort study.The study population comprised 2,187,317 subjects,using the Israeli medical corps data linked to the Israel National Cancer Registry with follow-up of up to 45 years.Exposure assessments were estimated by a spatial kriging interpolation model of SO2,serving as a marker for the dispersion of air pollution emitted from the complex during the study period.We found increased crude(HR=1.23,95%CI=1.17 to 1.29)and adjusted(HR=1.16,95%CI=1.10 to 1.21)risk of cancer with increased exposure to air pollution in HBA.The associations remained robust in analyses stratified by decade and socio-economic status.We found evidence of monotonically increased risk in five of 13 cancer categories(leukemia,melanoma,female breast,central nervous system,and thyroid tumors).Our findings strengthen the hypothesis that this exposure posed a carcinogenic risk during the study period.

The natural sources,extraction,and nephroprotective function of oleanolic acid and ursolic acid:a review

Oleanolic acid(OA)and ursolic acid(UA)are commonly present in the cuticular wax of many edible fruits and medicinal herbs.OA and UA belong to the group of bioactive pentacyclic triterpenoids,exhibiting a wide range of beneficial effects including protection for the kidneys,liver,heart,gastrointestinal tract,and spinal cord.Additionally,OA and UA exhibit antioxidant,anti-ferroptotic,anti-apoptotic,anti-inflammatory,anti-tumor,anti-viral,anti-diabetic,anti-microbial,anti-parasitic,analgesic,wound-healing,hypolipidemic,and hypoglycemic properties,often without notable side effects.Due to the extensive array of their positive functions,it is not feasible to thoroughly cover all aspects in this review.Therefore,the primary focus lies on reviewing the natural sources,extraction,and nephroprotective properties of OA and UA.To summarize,current literatures highlight the nephroprotective mechanisms of OA and UA,primarily involving inhibiting oxidative stress,endoplasmic reticulum stress,glycative stress,dyslipidemia,inflammation,apoptosis,pyroptosis,and renal fibrosis,promoting diuresis,as well as fine-tuning autophagy.

Influence of the continuing COVID-19 epidemic on sleep quality and psychological status of healthcare workers in private institutions

BACKGROUND On January 22,2020,Macao reported its first case of coronavirus disease 2019(COVID-19)infection.By August 2021,the situation had escalated into a crisis of community transmission.In response,the government launched a recruitment campaign seeking assistance and services of healthcare workers(HCWs)from the private sector throughout Macao.These participants faced concerns about their own health and that of their families,as well as the responsibility of maintaining public health and wellness.This study aims to determine whether the ongoing epidemic has caused them physical and psychological distress.AIM To examine the influence of COVID-19 on the sleep quality and psychological status of HCWs in private institutions in Macao during the pandemic.METHODS Data were collected from December 2020 to January 2022.Two consecutive surveys were conducted.The Pittsburgh Sleep Quality Index(PSQI)scale,Self-Rating Anxiety Scale(SAS),and Self-Rating Depression Scale(SDS)were employed as investigation tools.RESULTS In the first-stage survey,32%of HCWs experienced a sleep disorder,compared to 28.45%in the second-stage survey.A total of 31.25%of HCWs in the first-stage survey and 28.03%in the second had varying degrees of anxiety.A total of 50.00%of HCWs in the first-stage survey and 50.63%in the second experienced varying degrees of depression.No difference in PSQI scores,SAS scores,or SDS scores were observed between the two surveys,indicating that the COVID-19 epidemic influenced the sleep quality and psychological status of HCWs.The negative influence persisted over both periods but did not increase remarkably for more than a year.However,a positive correlation was observed between the PSQI,SAS,and SDS scores(r=0.428-0.775,P<0.01),indicating that when one of these states deteriorated,the other two tended to deteriorate as well.CONCLUSION The sleep quality,anxiety,and depression of HCWs in private institution in Macao were affected by the COVID-19 epidemic.While these factors did not deteriorate significantly,the negative effects persisted for a year and remained noteworthy.

Role of complex organic arsenicals in food in aggregate exposure to arsenic

For much of the world＇s population, food is the major source of exposure to arsenic.Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, evaluating foods as sources of exposure to arsenic is important in assessing risk and developing strategies that protect public health. Although most emphasis has been placed on inorganic arsenic as human carcinogen and toxicant, an array of arsenic-containing species are found in plants and animals used as foods. Here,we 2evaluate the contribution of complex organic arsenicals（arsenosugars, arsenolipids,and trimethylarsonium compounds） that are found in foods and consider their origins,metabolism, and potential toxicity. Commonalities in the metabolism of arsenosugars and arsenolipids lead to the production of di-methylated arsenicals which are known to exert many toxic effects. Evaluating foods as sources of exposure to these complex organic arsenicals and understanding the formation of reactive metabolites may be critical in assessing their contribution to aggregate exposure to arsenic.

Depression of Calcium Transients After Exposure to High K^+ Solution in Li^+-loaded Frog Twitch Muscle Fibres and Its Reversal by Exogenous Myo-inositol

Using Arsenazo Ⅲ as a myoplasmic calcium indicator, we have studied the calcium transients evoked by voltage-clamp depolarizing pulses in frog twitch muscle fibres which had been temporarily depolarized by 80 mmol/LK^+ in the absence or presence of myoplasmic Li^+. After the high K^+ exposure, for either a short (15 rain) or long(1 h) time, the post-K^+ calcium transients could gradually be restored to the level of the pre-K^+ ones, if the fibres were not loaded with Li^+.In contrast, the post-K^+ calcium transients of Li^+-loaded fibres could not fully recover,and were depressed in a Li^+ concentration-dependent manner.The mean amplitude of the post-K^+ responses recorded more than 3.5 h after 15 min high K^+ exposure was reduced to 56% of pre-K^+ control in the fibres which had been loaded with Li^+ in 20 mmol/L Li^+ Ringer's solution.This depression could be prevented or partially reversed by exogenous myo-inositol.More depression could be induced by 1 h high K^+ exposure, but the presence of exogenous myo-inositol could not clearly prevent the post-K^+ calcium transients from reduction.Assuming that high K^+ exposure caused a depletion of myo-inositol and probably other changes in the metabolism of inositol phospholipids in Li^+ loaded fibres,we conclude that some metabolites of phosphoinositides may play modulation roles in excitation-contraction coupling in frog twitch muscle fibres.

Mental health problems due to community violence exposure in a small urban setting

Objective:Studies conducted in large metropolitan inner-city communities with high violent crime rates have demonstrated an association between exposure to violence and mental health problems;therefore the purpose of this study was to determine if similar trends exist in smaller inner-city communities with substantially lower violent crime rates.Methods:One hundred twenty-six children and young adults living in inner-city Omaha,Nebraska,were screened for posttraumatic stress disorder(PTSD),depression,and anxiety symptoms and assessed for community violence exposure(CVE).Pearson’s correlation and analysis of variance were used to determine the relationship between PTSD,depression,and anxiety symptoms and CVE.Results:A statistically significant relationship was found between CVE and PTSD and anxiety symptoms among participants despite their having lower rates of exposure to violent events in com-parison with other studies.No association was found between violence and depression symptoms.Additionally,the presence of anxiety and depression,as well as increased age of participants,was associated with higher rates of PTSD symptoms.Conclusion:We recommend that health care providers in smaller cities,where the effects of violent crime may be underestimated or overlooked,be informed of the existence of this pub-lic health problem within their community and that they screen at-risk patients for mental health problems.

mgr-mir-9 implicates Meloidogyne graminicola infection in rice by targeting the effector MgPDI

MicroRNAs (miRNAs),a class of small non-coding RNAs,are crucial endogenous gene regulators in a range of animals,including plant-parasitic nematodes.Meloidogyne graminicola is an obligate sedentary endoparasite of rice and causes significant yield losses.A number of studies focused on the roles of M.graminicola effectors during the parasitic process;however,how nematode miRNAs regulate its effectors needs elucidating.In this research,we analyzed a cluster of M.graminicola miRNAs obtained at the second-stage juveniles (J2s) stage that are closely linked to the regulation of M.graminicola effectors.There are 49 767 105 total clean reads obtained from three libraries.A total of 233 known miRNAs and 21 novel miRNAs were identified.Among the known miRNAs,mgr-lin-4,mgr-mir-1,mgr-mir-100,mgrmir-86,mgr-mir-279,mgr-mir-87,mgr-mir-71,mgr-mir-9,mgr-mir-50,mgr-mir-72,and mgr-mir-34 are the most abundant11 miRNAs families.Moreover,the expression levels of selected miRNAs were validated by real-time quantitative PCR.We hypothesized that these miRNAs might regulate the expression of secreted effectors during the J2s stage to facilitate its infection.Consistent with this,we found that mgr-mir-9 targets MgPDI,an important M.graminicola effector mRNA.In addition to that,J2s treated with mgr-mir-9 mimics showed down-regulation of MgPDI expression and reduced reproductive ability,alluding mgr-mir-9 is involved in nematode infection.These results provide novel insight into the regulatory functions of M.graminicola miRNAs during the infection and identify miRNAs and their effector targets as potential key management targets to limit parasite survival during the early stages of infection.

Soft tissue swelling incidence using demineralized bone matrix in the outpatient setting

AIM To assess use of demineralized bone matrix(DBM) use in anterior cervical discectomy and fusion(ACDF) in outpatient setting.METHODS One hundred and forty-five patients with prospectively collected data undergoing single and two level ACDF with DBM packed within and anterior to polyetheretherketone(PEEK) cages. Two groups created, Group 1(75) outpatients and control Group 2(70) hospital patients. Prevertebral soft tissue swelling(PVSTS) was measured anterior to C2 and C6 on plain lateral cervical radiographs preoperatively and one week postoperatively and fusion assessed at two years. RESULTS There was no intergroup significance between preoperative and postoperative visual analogue scales(VAS)and neck disability index(NDI) scores between Group 1 and 2. Mean preoperative PVSTS in Group 1 was 4.7 ± 0.2 mm at C2 level and 11.1 ± 0.5 at C6 level compared to Group 2 mean PVSTS of 4.5 ± 0.5 mm and 12.8 ± 0.5, P = 0.172 and 0.127 respectively. There was no radiographic or clinical evidence of adverse reaction noted. In Group 1 mean postoperative PVSTS was 5.5 ± 0.4 mm at C2 and 14.9 ± 0.6 mm at C6 compared Group 2 mean PVSTS was 4.9 ± 0.3 mm at C2 and 14.8 ± 0.5 mm at C6, P = 0.212 and 0.946 respectively. No significant increase in prevertebral soft tissue space at C2 and C6 level demonstrated.CONCLUSION ACDF with adjunct DBM packed PEEK cages showed a statistical significant intragroup improvement in VAS neck pain scores and NDI scores(P = 0.001). There were no reported serious patient complications; post-operative radiographs demonstrated no significant difference in prevertebral space. We conclude that ACDF with DBMpacked PEEK cages can be safely done in an ASC with satisfactory outcomes.

Identification and Quantification of Aerosol Polar Oxygenated Compounds Bearing Carboxylic or Hydroxyl Groups.1.Method Development

In this study,a new analytical technique was developed for the identification and quantification of multifunctional compounds containing simultaneously at least one hydroxyl or one carboxylic group,or both.This technique is based on derivatizing first the carboxylic group(s) of the multifunctional compound using an alcohol (e.g.,methanol,1-butanol) in the presence of a relatively strong Lewisacid (BF3) as a catalyst.This esterification reaction quickly and quantitatively converts carboxylic acids to their ester forms.The second step is based on silylation of the ester compounds using bis(trimethylsilyl) trifluoroacetamide (BSTFA) as the derivatizing agent.For compounds bearing ketone groups in addition to carboxylic and hydroxyl groups,a third step was used based on PFBHA derivatizationof the carbonyls.Different parameters including temperature,reaction time,and effect due to artifacts were optimized.A GC/MS in EI and in methane-CI mode was used for the analysis of these compounds.The new approach was tested on a number of multifunctional compounds.The interpretation of their EI (70 eV) and CI mass spectra shows that critical information is gained leading to unambiguous identification of unknown compounds.For example,when derivatized only with BF3-methanol,their mass spectra comprise primary ions at m/z M ·+ +1,M ·+ +29,and M ·+ - 31 for compounds bearing only carboxylic groups and M ·+ +1,M ·+ +29,M ·+ -31,and M ·+ -17 for those bearing hydroxyl andcarboxylic groups.However,when a second derivatization (BSTFA) was used,compounds bearing hydroxyl and carboxylic groups simultaneously show,in addition to the ions observed before,ions at m/z M ·+ +73,M ·+ -15,M ·+ -59,M ·+ -75,M ·+ -89,and 73.To the best of our knowledge,this technique describes systematically for the first time a method for identifying multifunctional oxygenated compounds containing simultaneously one or more hydroxyl and carboxylic acid groups.

Long-term culture-induced phenotypic difference and efficient cryopreservation of small intestinal organoids by treatment timing of Rho kinase inhibitor

To investigate a suitable long-term culture system and optimal cryopreservation of intestinal organoid to improve organoid-based therapy by acquiring large numbers of cells.METHODSCrypts were isolated from jejunum of C57BL/6 mouse. Two hundred crypts were cultured in organoid medium with either epidermal growth factor/Noggin/R-spondin1 (ENR) or ENR/CHIR99021/VPA (ENR-CV). For subculture, organoids cultured on day 7 were passaged using enzyme-free cell dissociation buffer (STEMCELL Technologies). The passage was performed once per week until indicated passage. For cryopreservation, undissociated and dissociated organoids were resuspended in freezing medium with or without Rho kinase inhibitor subjected to different treatment times. The characteristics of intestinal organoids upon extended passage and freeze-thaw were analyzed using EdU staining, methyl thiazolyl tetrazolium assay, qPCR and time-lapse live cell imaging.RESULTSWe established a three-dimensional culture system for murine small intestinal organoids using ENR and ENR-CV media. Both conditions yielded organoids with a crypt-villus architecture exhibiting Lgr5+ cells and differentiated intestinal epithelial cells as shown by morphological and biochemical analysis. However, during extended passage (more than 3 mo), a comparative analysis revealed that continuous passaging under ENR-CV conditions, but not ENR conditions induced phenotypic changes as observed by morphological transition, reduced numbers of Lgr5+ cells and inconsistent expression of markers for differentiated intestinal epithelial cell types. We also found that recovery of long-term cryopreserved organoids was significantly affected by the organoid state, i.e., whether dissociation was applied, and the timing of treatment with the Rho-kinase inhibitor Y-27632. Furthermore, the retention of typical morphological characteristics of intestinal organoids such as the crypt-villus structure from freeze-thawed cells was observed by live cell imaging.CONCLUSIONThe maintenance of the characteristics of intestinal organoids upon extended passage is mediated by ENR condition, but not ENR-CV condition. Identified long-term cryopreservation may contribute to the establishment of standardized cryopreservation protocols for intestinal organoids for use in clinical applications.

Interaction between Soil Moisture and Air Temperature in the Mississippi River Basin

Increasing air temperatures are expected to continue in the future. The relation between soil moisture and near surface air temperature is significant for climate change and climate extremes. Evaluation of the relations between soil moisture and temperature was performed by developing a quantile regression model, a wavelet coherency model, and a Mann-Kendall correlation model from 1950 to 2010 in the Mississippi River Basin. The results indicate that first, anomaly air temperature is negatively correlated to anomaly soil moisture in the upper and lower basin, and however, the correlation between them are mixed in the middle basin. The correlation is stronger at the higher quantile (90th) of the two variables. Second, anomaly soil moisture and air temperature show strong coherency in annual frequency, indicating that the two variables are interannually correlated. Third, annual air temperature is significant negatively related to soil moisture, indicating that dry (wet) soil leads to warm (cool) weather in the basin. These results have potential application to future climate change research and water resource management. Also, the strong relationship between soil moisture and air temperature at annual scale could result in improved temperature predictability.

Nonlinear Model of Image Noise: An Application on Computed Tomography including Beam Hardening and Image Processing Algorithms

This paper proposes a more inclusive statistical model for predicting image noise in Computed Tomography (CT), associated with scanning factors, considering the effect of beam hardening and image processing filters. It is based on power functions where the levels of the parameters will determine the rate of noise variation with respect to a given scanning factor. It includes the influence of tube potential, tube current, slice thickness, Field of View (FOV), reconstruction methods and post-processing filters. To validate the model, tomographic measurements were made by using a PMMA phantom that simulates paediatric head and adult abdomen, a PET bottle was used to simulate the head of the new-born. The influence of ROI (Region Of Interest) size over nonlinear model parameters was analysed, and high variations of powers of attenuation and FOV were found depending on ROI size. A nonlinear robust regression method was used. The validation was performed graphically by weighted residual analysis. A nonlinear noise model was obtained with an adjusted coefficient of determination for ROI sizes between 10% and 70% of the phantom diameter or FOV. The model confirms the significance of the tube current, slice thickness and beam hardening effect on image. The process of estimation of the parameters of the model by Nonlinear Robust Regression turned out to be optimal.

Influence of Azo Dye on Metabolism of Phosphorus Accumulating Organisms Linked to Transformation of Intracellular Storage Products

In this study, the influence of azo dye of methyl red (MR) on COD, dye and phosphorus removal and the transformation of polyhydroxyalkanoate (PHA) and glycogen of phosphate accumulating organisms in enhanced biological phosphorus removal (EBPR) system were investigated. The results indicated COD and dye removal efficiencies were decreased from 97.9% to 72.8% and 99.7% to 82.0%, respectively, when MR concentration was increased from 0 to 40 mg/L. Low MR concentration (5 mg/L) had no influence on P removal and transformation of PHA and glycogen. However, P removal, PHA production and consumption, and glycogen replenishment were seriously inhibited at high MR concentration, while glycogen hydrolysis was simulated at MR concentration of 20 and 40 mg/L. The transformations of PHA and glycogen at aerobic condition were more sensitive to those at anaerobic condition at high MR concentration. These results demonstrated dye and its intermediate products would inhibit the metabolism of polyphosphate accumulating organisms, which should be taken into account in future work.

UV Light Induced Transformation of 1-Methylnaphthalene in the Presence of Air and Its Implications for Contaminants Research

Understanding chemical transformations of contaminants and the resulting products is extremely important in devising proper monitoring methods for such contaminants and in assessing potential human exposure to the transformation products in the environment. Ultraviolet (UV) light from the sun can induce various photochemical transformations of contaminants in the environment. Alkylnaphthalenes are light-molecular-weight polycyclic aromatic hydrocarbons (PAHs) which are one of the most widespread organic pollutants present in ambient air as a result of a variety of incomplete combustion sources. In this study, 1-methylnapthalene,a typical example of an alkylnaphthalene, was subjected to UV irradiation to investigate its transformation in the presence and absence of air. Twenty-one products were detected in the reaction mixtures. Some photo-oxidation products were identified, including both ring-opened and ring-retained oxygenated compounds, such as 1-naphthaldehyde, 1-naphthoic acid, 1-naphthalenemethanol and phthalic anhydride. Although dimeric products were observed in the presence of air, more were found in the presence of helium or argon gas, indicating a different photo-oxidation pathway from those commonly observed in other media, such as water. Under just 48 hours of exposure to the UV light in the presence of air, three major products were formed with a production yield of about 10% each. Compared to 1-methylnapthalene, the UV induced transformation products observed in this study are more volatile, acidic, water soluble or toxic. The formation of these products may significantly change our understanding of the risks assessed solely from the parent compound in contaminants research and supports the inclusion of airborne transformations of the parent compound in risk assessment.

SELECTIVE TOXICITY OF RHODAMINE 123 ON CARCINOMA CELL IN VITRO

The selective toxicity of the mitochondria-specific cationic fluorescent dye rhodamine 123 (Rh-123) on He La cells in culture was studied. In this report, we demonstrate that with continuous exposure, Rh-123 markedly inhibited the growth of HeLa cells but had little effect on normal human kidney fibroblasts. With continuous exposure to Rh-123, the growth rate, colony forming ability, anl mitotic index of HeLa cells were decreased. The mechanism of toxicity of Rh-123 on HeLa cells was investigated by EM and enzyme cytochemistry stain. The mitochondria of carcinoma cells were the main targets for the inhibitory action of Rh-123, since they selectively accumulated the dye. At the dosage of Rh-123 which was toxic to HeLa cells, the structure and function of mitochondria were disrupted, as the mitochondria-related enzymes, i.e., ATPase, LDH and SDH were inhibited. The possible mechanism of the action of Rh-123 on HeLa cells is briefly discussed.