Aerosols optical depth and Ångström exponent over different regions in Garhwal Himalaya, India

Aerosol optical depth (AOD) and Ångström exponent (AE) are observed to be important parameters in understanding the status of ambient aerosol concentration over a particular location and depend not only upon the local but also on the large-scale dynamics of the atmosphere. The present article analyses the AOD and AE parameters retrieved with Moderate Resolution Imaging Spectrometer (MODIS) and Multi-angle Imaging Spectro-Radiometer (MISR) instruments onboard satellites, for the upper (Chamoli) and foothill (Dehradun) regions of Garhwal Himalaya in Uttarakhand, India, from 2006 to 2015. Aerosol properties are investigated at monthly, seasonal, and annual scales. The monthly mean values of MODIS-derived AOD and AE were observed to be 0.18 (± 0.14) and 1.05 (± 0.43) respectively over the Dehradun region. The seasonal maximums in AOD with MODIS and MISR were observed as 0.23 ± 0.06 and 0.29 ± 0.07 respectively in the pre-monsoon season, and the minimum values (0.099 ± 0.02) were observed in the post-monsoon season, over the Dehradun region. In contrast, in the Chamoli region, the maximum AOD (MODIS) was 0.21 ± 0.06 observed in the monsoon season and the minimum was 0.036 ± 0.007 in the post-monsoon season. Over a decade, the AE for Chamoli and Dehradun was found to vary from 0.07 to 0.17 and from 0.14 to 0.20 respectively. The median AE for Chamoli and Dehradun was found to be 1.49 and 1.47 respectively, marking the dominance of fine mode particles of anthropogenic origin. Observations show the presence of dust and polluted dust resulting from the long-range transport from the west. The comparison of AOD values from the two sensors shows a significant correlation (0.73) with slightly higher values from MISR over the year. The results obtained are important in understanding the climatic implications due to the atmospheric aerosols over the abovementioned Himalayan region of Uttarakhand, India.

Prescriber and dispenser perceptions about antibiotic use in acute uncomplicated childhood diarrhea and upper respiratory tract infection in New Delhi: Qualitative study

OBJECTIVE:

The objective of the study was to explore the prescribing practices, knowledge, and attitudes of primary care doctors and community pharmacists, regarding antibiotic use in acute upper respiratory tract infections (URTI) and diarrhea in children to better understand causes of misuse and identify provider suggestions to change such behavior.

MATERIALS AND METHODS:

Two focus group discussions (FGDs) each were conducted with primary care government doctors (GDs), private general practitioners (GPs), pediatricians, and community pharmacists in Delhi. Each FGD had 8–12 participants and lasted 2 h. Furthermore, 22 individual face-to-face semi-structured interviews were conducted with providers of varying type and experience at their workplaces. Thematic and summative qualitative content analysis was done.

RESULTS:

All groups admitted to overusing antibiotics, GPs appearing to use more antibiotics than GDs and pediatricians for URTI and diarrhea in children. Pharmacists copy the prescribing of neighborhood doctors. Antimicrobial resistance (AMR) knowledge was poor for all stakeholders except pediatricians. Causes for prescribing antibiotics were patient pressure, profit motive, lack of follow-up and in addition for GDs, workload, no diagnostic facility, and pressure to use near-expiry medicines. Knowledge was gained through self-experience, copying others, information from pharmaceutical companies, and for some, training, continuous medical education/conferences. All groups blamed other professional groups/quacks for antibiotic overuse. Interventions suggested were sensitizing and empowering prescribers through training of providers and the public about the appropriate antibiotic use and AMR and implementing stricter regulations.

CONCLUSIONS:

A package of interventions targeting providers and consumers is urgently needed for awareness and change in behavior to reduce inappropriate community antibiotic use.

Malnutrition in Children: A Serious Public Health Issue in Nepal

DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7439 Health Prospect 2012;11:61-62

Molecular data suggest population expansion and high level of gene flow in the Plain Tiger (Danaus chrysippus; Nymphalidae: Danainae)

In the present study, we sequenced the individuals of the Danaus chrysippus from the different altitudinal ranges in the western Himalayan state of Uttarakhand, India and compared with other global published data across its distribution range using the cytochrome oxidase c subunit-I (COI). Among the sequences generated in this study, we observed total six haplotypes with intra-species sequence divergence of 0.001-0.009. Whereas the combined data generated a total of 24 haplotypes. The genetic diversity and neutrality test indices suggested overall population expansion of the species. This has also been supported by the MJ Network as it shows the star-like topology and formation of one core haplotype with maximum frequency distribution to the multiple locations. Whereas, the phylogenetic tree shows mixing of the haplotype from the different locations to the same clade. Haplotype arrangement in both phylogenetic tree and MJ Network is not clustered as per their geographic affinity, which suggests incomplete lineage shorting and recent population expansion or colonizations to the new area.

Knowledge and perceptions on antibiotic use and resistance among high school students and teachers in New Delhi, India: A qualitative study

Objective:

To explore the perceptions and knowledge of school teachers and students about antibiotic use, resistance, and suggestions for practical interventions for the rational use of antibiotics.

Methodology:

Five focus group discussions (FGDs) with high school students (Class: 9–11) and five with teachers were conducted in two private and three public schools (one teacher and one student FGD per school) in five municipal wards of Delhi. Qualitative data on antibiotic knowledge, resistance, and behaviors with respect to antibiotics use were collected. There were 4–8 persons per teacher FGD and 15–20 persons per student FGD. FGDs were analyzed using “thematic analyses.”

Results:

Students had poor knowledge regarding antibiotics and antibiotic resistance, while only some teachers had a basic understanding. Four broad themes needing attention emerged: definition of antibiotic and antibiotic resistance, antibiotic use behavior, doctor–patient relationship, and interventional strategies suggested to curtail the misuse of antibiotics and to spread awareness. In order to tackle these problems, both groups suggested a multipronged approach including robust public awareness campaigns also involving schools, better doctor–patient relationships, and stronger regulations.

Conclusions:

Although students and teachers exhibited poor knowledge about antibiotic use and resistance, they were keen to learn about these issues. School education programs and public education could be used to shape correct perceptions about antibiotic use among all stakeholders including children. This may help in the containment of antibiotic resistance and thus preservation of antibiotics for future generations.

Bridging the prebiotic and RNA worlds: prebiotic RNA synthesis on clay

Abstract Progress towards the laboratory demonstration of the steps in the prebiotic origin of the RNA world is reviewed. Montmorillonite clay catalyzes the formation of RNAs containing 6-14 monomer units from the activated mononucleotides of A, C, G, I and U. The RNAs formed have 3', 5'- and 2', 5'-links, pyrophosphate links and have both linear and cyclic chains. The purine oligonucleotides have more 3', 5'- links while the pyrimidine nucleotides have more 2', 5'-linkages. Template-directed synthesis on the heterogeneous oligo(C)s formed on mont- morillonite yields the corresponding oligo(G)s. The dimer fraction formed in the reaction of a binary mixture of a purine and pyrimidine nucleotide shows sequence selectivity with about a 20 fold excess of the 5'-purine-pyrimidine dimer over that of the 5'-pyrimidine-purine dimer. RNAs as long as 50 mers are formed by the elongation of a decamer bound to montmorillonite by the daily addition of activated monomer to it over a 14-day time period.

Irrational use of antibiotics and role of the pharmacist: an insight from a qualitative study in New Delhi, India

WHAT IS KNOWN AND OBJECTIVE

The overall volume of antibiotic consumption in the community is one of the foremost causes of antimicrobial resistance. In developing countries like India, pharmacists often dispense 'prescription-only' drugs, like antibiotics, to patients who do not have a prescription. Not much data is available regarding detailed information on behaviour of antibiotic use by community pharmacists which is of particular significance to develop a suitable and sustainable intervention programme to promote rational use of antibiotics. A qualitative study was conducted to understand the dispensing practices and behaviour of community pharmacists to develop policy interventions that would improve the use of antibiotics at the community level.

METHODS

Focus group discussions (FGDs) were held for five municipal wards of Delhi with retail pharmacists, public sector pharmacists and the office bearers of pharmacists' associations. Data on antibiotic use and resistance were collected earlier from these five wards. FGDs (n = 3 with 40 pharmacists) were analysed through grounded theory.

RESULTS AND DISCUSSION

Four broad themes identified were as follows: prescribing and dispensing behaviour; commercial interests; advisory role; and intervention strategies for rational use of antibiotics. FGDs with pharmacists working in the public sector revealed that, besides the factors listed above, overstock and near-expiry, and under-supply of antibiotics promoted antibiotic misuse. Suggestions for interventions from pharmacists were the following: (i) education to increase awareness of rational use and resistance to antibiotics; (ii) involving pharmacists as partners for creating awareness among communities for rational use and resistance to antibiotics; (iii) developing an easy return policy for near-expiry antibiotics in public sector facilities; and (iv) motivating and showing appreciation for community pharmacists who participate in intervention programmes.

WHAT IS NEW AND CONCLUSIONS

Inappropriate antibiotic dispensing and use owing to commercial interests and lack of knowledge about the rational use of antibiotics and antibiotic resistance were the main findings of this in-depth qualitative study. Community pharmacists were willing to participate in educational programme aimed at improving use of antibiotics. Such programmes should be initiated within a multidisciplinary framework including doctors, pharmacists, social scientists, government agencies and non-profit organizations.

Factors influencing primary care physicians to prescribe antibiotics in Delhi India

BACKGROUND

it is necessary to understand physician's prescribing behaviour in order to develop interventions that will effectively improve the use of antibiotics.

OBJECTIVE

to explore the factors that influence primary care physicians to prescribe antibiotics and to investigate possible interventions.

METHODS

focus group discussions (FGDs) were used to explore the perspectives of primary care physicians in the public and private sectors from five municipal wards (residential localities) of Delhi from where data on antibiotic use and resistance were collected. FGDs (n = 3 with 36 prescribers) were analysed through grounded theory.

RESULTS

three broad themes identified were as follows: behavioural characteristics of doctors and patients; laxity in regulation of prescribing and dispensing antibiotics and intervention strategies to decrease misuse of, and resistance to, antibiotics. Important factors identified for antibiotic prescriptions by doctors were diagnostic uncertainty, perceived demand and expectation from the patients, practice sustainability and financial considerations, influence from medical representatives and inadequate knowledge. For public sector doctors, besides the above, overstocked and near-expiry drugs and lack of time were the factors that promoted antibiotic overuse. Doctors also identified certain patient behaviour characteristics and laxity in regulation for prescribing and dispensing of antibiotics as aggravating the problem of antibiotic misuse. Interventions like Continuing Medical Educations for doctors, awareness raising of patients, shared decision making and stricter rules and regulations were suggested to promote rational use of antibiotics in the community.

CONCLUSION

exploration of doctors' antibiotic use practices and possible interventions will be helpful in carrying out interventions to promote appropriate use of antibiotics in the community.

Air pollution induced changes in the photosynthetic pigments of selected plant species

Changes in the concentration of different photosynthetic pigments (Chlorophyll and carotenoids) were determined in the leaves of six tree species exposed to air pollution due to vehicular emissions. The six tree species, which are all economically important because of their being fruit bearers, used for timber fodder and as road side trees on the basis of their air pollution tolerance index. These included Mangifera indica L., Tectona grandis Linn.f , Shorea robusta Gaertn.f., Holoptelea integrifolia (Roxb.) Planch, Eucalyptus citridora Hook. Syn. and Mallotus philippinensis Muell-Arg. Reduction in chlorophyll 'a', 'b' and carotenoid was recorded in the leaf samples collected from polluted areas when compared with samples from control areas. The highest reduction in total chlorophyll was observed in Holoptelea integrifolia (Roxb.) (48.73%) Planch whereas, the lowest reduction (17.84 %) was recorded in Mallotus philippinensis Muell-Arg. Similarly in case of carotenoid contents, highest reduction (43.02%) was observed in Eucalyptus citridora, and lowest in Mallotus philippinensis Muell-Arg (19.31%). The data obtained were further analyzed using one-way ANOVA and a significant change was recorded in the studied parameters. These studies clearly indicate that the vehicular induced air pollution reduces the concentration of photosynthetic pigments in the trees exposed to road side pollution.

Effect of bioaccumulation of cadmium on biomass productivity, essential trace elements, chlorophyll biosynthesis, and macromolecules of wheat seedlings

Soil contamination with heavy metals has become a worldwide problem, leading to losses in agricultural yield and hazardous human health effects as they enter the food chain. The present investigation was undertaken to examine the influence of cadmium (Cd2+) on the wheat (Triticum aestivum L.) plant. Cd2+ accumulation and distribution in 3-wk-old seedlings grown in nutrient medium containing varying concentrations of Cd2+ (control, 0.25, 0.50, 1.0, 2.5, and 5.0 mg/L) was monitored. The effect of varying Cd2+ concentrations up to 21 d on biomass productivity, plant growth, photosynthetic pigments, protein, amino acids, starch, soluble sugars, and essential nutrients uptake was studied in detail to explore the level up to which the plant can withstand the stress of heavy metal. Plants treated with 0.5, 1.0, 2.5, and 5.0 mg/L Cd2+ showed symptoms of heavy-metal toxicity as observed by various morphological parameters which were recorded with the growth of plants. The root, shoot-leaf length and the root, shoot-leaf biomass progressively decreased with increasing Cd2+ concentration in the nutrient medium. Cd2+ uptake and accumulation was found to be maximum during the initial growth period. Cd2+ also interfered with the nutrients uptake, especially calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe2+), zinc (Zn2+), and manganese (Mn2+) from the growth medium. Growth reduction and altered levels of major biochemical constituents such as chlorophyll, protein, free amino acids, starch, and soluble sugars that play a major role in plant metabolism were observed in response to varying concentrations of Cd2+ in the nutrient medium. In the present study, the effects of Cd2+ on growth, biomass productivity, mineral nutrients, chlorophyll biosynthesis, protein, free amino acid, starch, and soluble sugars in wheat plants was estimated to establish an overall picture of the Cd2+ toxicity at structural and functional levels.

Identification of new photoreduction products of pentachlorophenol

Pentachlorophenol (PCP), a fungicide and insecticide, leaves behind considerable residue in the environment in the form of unreacted molecule, metabolites and photoreduction products. Most of the previously reported photoproducts have resulted from dechlorination of the parent molecule. We have shown that photoreduction of PCP also proceeds by photoreduction of the parent molecule at carbons 2 and 4. These products were identified and characterized as 2-dehydro-2,3,4,5,6-pentachlorocyclohexanone (II) and 2,3,4,5,6-pentachlorocyclohexanone (IV). Both of them display keto-enol tautomerism. Identification and characterization of new photoproducts of PCP is significant for determining its overall environmental impact in the ecosystem.

Evaluation of UV-radiation induced singlet oxygen generation potential of selected drugs

Photosensitization reaction of drugs leading to the formation of reactive oxygen species under ultraviolet radiation (UVR) can cause tissue injury, resulting in damage to various cellular macromolecules. The aim of this study was to determine the singlet oxygen generation potential of some commonly used antibiotics so that due precautions can be exercised to minimize their photosensitizing action and oxidative stress potential. The selected antibiotics were examined for their ability to produce singlet oxygen (1O2) under artificial UVA (320-400 nm). Singlet oxygen generation of various screened antibiotics under UVA is of the following order: Nalidixic acid > Amphotericin-B > Cephradine > Cefazolin > Nafcillin > Cephalothin > Ampicillin > Cephalexin > Puromycin > Kanamycin > Lincomycin > Tetracycline > Nystatin > Gentamicin sulphate. Nalidixic acid, the most potent generator of 1O2 among the screened antibiotics, was selected to carry out further studies. Certain specific quenchers of 1O2 such as beta-carotene, 1,4-diazabicyclo[2.2.2] octane (DABCO), and sodium azide (NaN3) accorded significant inhibition in the production of 1O2. The results suggest that precautions are necessary to avoid ultraviolet radiation after the intake of photoreactive drugs, especially in tropical countries such as India. These findings are significant because UVB radiation is reportedly increasing on earth surface in part due to depletion of stratospheric ozone layer. The selected drugs are commonly used for the treatment of various diseases. Thus, the synergistic action of both can lead to undesirable phototoxic responses.

Trauma patients with positive cultures have higher levels of circulating macrophage migration inhibitory factor (MIF)

Macrophage migration inhibitory factor (MIF) is a pituitary "stress" hormone that plays a critical role in the host immune response. The aims of the study were to determine whether MIF was detectable in the circulation of trauma patients, to assess whether MIF levels were associated with injury severity, days post injury, infection, and to examine concentrations of other pro-inflammatory cytokines in circulation. We collected plasma samples from 35 trauma (multiple injury) patients and 18 healthy controls. Concentrations of MIF, TNF-alpha, IL-1beta, and IL-6 were measured by ELISA. Average MIF concentration in plasma of trauma patients was 14 fold higher than that of healthy controls (19,439+/-2,615 pg/ml in trauma vs 1,337+/-286 pg/ml in control; p=0.0002). There was no correlation between MIF values and injury severity score or days post injury. Average level of IL-6 in trauma patients was 587+/-85 pg/ml but was not correlated with MIF concentration. TNF-alpha and IL-1beta were not detectable in trauma patients or healthy controls. Higher MIF levels were associated with positive cultures (blood, urine, sputum, wound). These data suggest that MIF may be a possible indicator of infection in trauma patients.

EVALUATION OF UV-INDUCED SUPEROXIDE RADICAL GENERATION POTENTIAL OF SOME COMMON ANTIBIOTICS

Photosensitization reaction of drugs leading to the formation of reactive oxygen species (ROS) cause tissue injury causing damage to various cellular macromolecules. The aim of this study was to determine the superoxide anion (O2-) generation potential of commonly used antibiotics so that due precaution could be exercised to minimize their photosensitizing action and oxidative stress potential. The selected antibiotics were examined for their ability to produce (O2-) under sunlight and artificial UVA (320-400 nm) and UVB (290-320 nm). Lincomycin, cephalothin and erythromycin generated significant amount of O2- under various irradiation conditions. Superoxide dismutase (SOD), an enzymatic quencher of O2- inhibited O2- production in all drugs tested. The results suggest that due precaution are necessary to avoid ultraviolet radiation (UVR) after the intake of photoreactive drugs, especially in tropical and sub tropical countries.

Effect of lindane on the growth and metabolic activities of cyanobacteria

The effect of lindane was studied in Cyanobacteria (Anabaena) by estimating its growth pattern, biomass yield, chlorophyll content, and total starch and protein content. The results reveal that exposure of Anabaena with 0.5, 1.0, 1.5, and 2.0 ppm levels of lindane will have drastic effects on biomass production and photosynthetic rate. Since Cyanobacteria are a primary source of aquatic food web and important biofertilizer for rice cultivation, their protection from residual effects of lindane is essential for enriched soil fertility.

Prostaglandin E2 suppressed IL-15-mediated human NK cell function through down-regulation of common gamma-chain

NK cell function is regulated by cytokines and certain biochemical mediators in a positive or negative manner. This study was performed to investigate the suppressive effects of PGE(2) on IL-15-activated human NK cell function. Purified NK cells were cultured with 200 ng/ml IL-15 for 2 days in the presence or absence of 10-200 ng/ml PGE(2). PGE(2) significantly suppressed NK cell-mediated cytotoxicity and IFN-gamma production at the secretional and the transcriptional levels. We also evaluated the effect of PGE(2) on the IL-15R complex that consists of IL-2Rbeta, common gamma-chain (gamma(c)-chain), and a specific chain IL-15Ralpha. Percentage of positive cells and number of binding sites for gamma(c)-chain were significantly increased after IL-15 treatment; however, a substantial decrease was observed with PGE(2) cotreatment. In contrast, constitutive expression of IL-2Rbeta was significantly decreased after IL-15 treatment, with no change detected in the presence of PGE(2.) At the transcriptional level, neither IL-15 nor PGE(2) had significant effects on the expression of beta- or gamma(c)-chains. There was a 3-fold increase in the expression of IL-15Ralpha at the transcriptional level that peaked at 8 h after IL-15 treatment; however, PGE(2) had no significant effect. Suppression of NK function by PGE(2) was not due to the endogenous production of IL-4, IL-10, or TGF-beta(1) by NK cells. These results suggest that down-regulation of surface expression of gamma(c)-chain on NK cells may be one mechanism through which PGE(2) mediates suppression of IL-15-activated NK cell function.

An unusual photohaemolytic property of riboflavin

Riboflavin (RF) is a known photoreactive and phototoxic molecule. However, unlike other photosensitizers, it does not induce photohaemolysis of erythrocytes by itself. On the other hand, illuminated RF caused haemolysis but in the presence of serum or plasma. The kinetics of photohaemolysis in the presence of serum/plasma has been studied by monitoring the rate of haemolysis spectrophotometrically and morphological changes at erythrocytes membrane by scanning electron microscopy. We found that the extent of mammalian RBC membrane damage was dependent on the concentration of RF or hematoporphyrin (HP) (0-20 microgram/ml) and dose of sunlight (0-20 min). The RBC membrane-damaging potential of illuminated HP was not affected by the presence of plasma in the reaction system. Furthermore, RF showed a protective role against photohaemolysis caused by photoexcited HP if erythrocytes were preincubated with RF in the absence of serum/plasma. For mechanistic studies, biochemical parameters such as acetylcholinesterase activity (AChE) and formation of TBA-reactive substance (TBA-RS) were analysed in RBC and RBC+plasma under a similar set of experimental conditions. We observed about a 25% decrease in AchE activity as a synergistic action of RF or HP (20 microgram/ml) and sunlight (30 min) in both cases (RBC or RBC+plasma). Interestingly, illuminated RF caused about a 125% increase of TBA-RS in a reaction system consisting of RBC+plasma. On the other hand, an increase in the production of TBA-RS by illuminated RF was not observed in the absence of plasma/serum, in the reaction system. These results suggested that photooxidation of RBC membrane lipids by illuminated RF, under the influence of plasma/serum, may be one of the causes of membrane modification leading to RBC lysis.

Phototoxicity evaluation--Tetrahymena thermophila as an alternative model

Interest in utilizing an alternative to animal method for toxicological evaluation has received considerable attention due to cost effectiveness and the ethical issues involving animal experimentation. Alternative methods for phototoxicity evaluation are significant because of growing concern over increasing health effects due to stratospheric ozone depletion resulting in an increasing penetration of ultraviolet light-B radiation (UVB, 290-320 nm) which contributes to activation of chemical and biological molecules to potential phototoxic agents. The classic rabbit eye-irritancy test referred to as Draize test has been the subject of severe criticism by animal welfare groups. Dermal toxicity test using guinea pigs and mouse tail phototoxicity test is time consuming and requires a large number of laboratory animals. In photohaemolysis assay some of the phototoxic agents (such as riboflavin) react with the membrane proteins of the erythrocyte. However, in vitro test system using protozoa offers a promising alternative means of phototoxicity evaluation. Our previous studies have demonstrated that synergistic action of photochemically reactive agents and sunlight produces lethal effects to Paramecium but the protozoan has not received serious consideration for use as an alternative model for phototoxicity evaluation. In the present communication we have described the potential application of Tetrahymena as an alternative model to study the radiation-induced changes both in the presence or absence of photoreactive chemical agents. This model is likely to provide scope for studying the biological effects of environmental UVB radiation, DNA damage and defence against oxidative stress.

Agricultural produce in the dry bed of the River Ganga in Kanpur, India--a new source of pesticide contamination in human diets

Vegetables grown in the dry bed field of the River Ganga in Kanpur, an important industrial city of North India, were analysed for the pesticides hexachlorocyclohexane (HCH), dichlorodiphenyl trichloroethane (DDT), their isomers and metabolites at three different sites. Residues of both the pesticides were found in all the samples. Mean levels of 109.35, 136.76 and 145.93 microg HCH/kg and 6.64, 49.3 and 46.70 microg DDT/kg were found in the rural upstream, city and downstream industrial areas, respectively. The mean total HCH and DDT levels were within safe limits as per the Indian Standard but some samples had HCH levels above the WHO/FAO limit. The pesticide residue level in vegetables was several fold higher than their surrounding sandy soil and could pose health problems since these popular vegetables are consumed regularly by the population.

Copper(II) as an efficient scavenger of singlet molecular oxygen

Reactive oxygen species (ROS) are considered to play an important role in tissue injury that damages DNA, proteins, carbohydrates and lipids. Increased production of ROS and/or decreased efficiency of antioxidant defense system has been shown to contribute to a number of degenerative processes including cancer and AIDS. Among the various forms of ROS, singlet oxygen (1O2), which is generated predominantly in photosensitization reactions, is of particular physiologic significance because of its selectively long life in aqueous solution, its ability to cross the cell membrane barrier and high reactivity towards biomolecules. In the present study, the 1O2 scavenging potential of Cu(II) has been evaluated by (i) generating 1O2 by photosensitization of rose bengal (RB), (ii) establishing 1O2 quenching with recognized 1O2 scavengers like sodium azide, DABCO and (iii) examining the effect of Cu(II) in scavenging of 1O2. The results revealed that Cu(II) inhibited the rate of 1O2 production by 88%, 68%, 40%, 21% and 10% at a concentration of 10(-2) M, 5 x 10(-3) M, 10(-3) M; 5 x 10(-4) M, and 10(-4) M, respectively. Under similar experimental condition, sodium azide or DABCO at 10(-2) M inhibited the 1O2 production by 86% and 88%, respectively. Other 1O2 generating photosensitizer like hematoporphyrin, riboflavin and methylene blue also produced identical results with Cu(II) but Fe(II), Fe(III), Zn(II) or As(III) did not produce any quenching of 1O2. Presence of a copper binding peptide (Gly-Gly-His) in the reaction system reduced the 1O2 scavenging capacity of Cu(II) by 52-66% depending upon the UV dose. The 1O2 scavenging property of metal ion appears to have an advantage to reduce the oxidative damage of photodynamic reactions in order to prevent ROS-induced toxicity reactions.

UVB-induced reduction in biomass and overall productivity of cyanobacteria

Effect of middle wave ultraviolet radiation (UVB) was studied in three different species of cyanobacteria (Nostoc, Anabaena and Scytonema) by estimating their growth pattern, biomass yield, chlorophyll content, total starch and protein content. The results show that exposure of the cyanobacteria with UVB dose corresponding to an increase or decrease of 20% in its environmental flux will have drastic effects on biomass production, photosynthetic rate and nitrogen fixation. Cyanobacteria are primary sources of marine food web and an important biofertilizer; therefore, their protection from increasing threat of stratospheric ozone depletion will be necessary to maintain the ecological balance.

Expression of inducible nitric oxide synthase in human lungs

The aim of this study was to investigate the expression of inducible nitric oxide synthase (iNOS) in lungs of patients with or without adult respiratory distress syndrome (ARDS). We compared the expression of iNOS by immunohistochemical analysis and polymerase chain reaction in the human lungs collected during open-lung biopsy or at autopsy. The expression of iNOS mRNA was present in all lung samples; however, only 3 out of 11 lung samples showed weak staining for iNOS. Although the involvement of nitric oxide in animal models of ARDS is reported, production of nitric oxide in human lungs is still controversial. The data presented here suggest that human lungs express iNOS mRNA but that the production of iNOS protein may be tightly regulated and is expressed in pulmonary inflammation.

High sensitivity of tubifex for ultraviolet-B

Phytoplankton and zooplankton serve as major food material for primary and secondary consumers in the marine food web. Although phytoplankton are primary targets to UV radiation damaging effects, we have demonstrated that stratospheric ozone depletion will affect zooplankton to contribute to inhibition in biomass production. In this study, an annilid Tubifex was irradiated under UVA, UVB, UVC or direct sunlight to demonstrate behavioral changes (motility and mortality). The organism showed varying degrees of sensitivity towards UVB and UVC. Even a small increment in UVB resulted in high degree of mortality. Interestingly, water turbidity seems to have a protective effect against UV exposure. These results strongly suggest that a change in UVB flux has direct impact on biomass production.

Effect of aminoguanidine on in vivo expression of cytokines and inducible nitric oxide synthase in the lungs of endotoxemic rats

Endotoxemia results in the release of multiple mediators such as tumor necrosis factor alpha (TNF-infinity), interleukin-1 beta (IL-1 beta), and nitric oxide (NO), which is thought to be responsible for the hypotension of septic shock. Although there are many reports on the presence of these mediators in serum, in vivo expression of TNF-infinity, IL-1 beta and inducible nitric oxide synthase (iNOS) at the tissue level has not been studied extensively. We investigated in vivo expression of these cytokines and iNOS in the lungs of rats that were injected with saline, endotoxin or endotoxin plus aminoguanidine (AG), an inhibitor of iNOS. Expression of TNF-infinity, IL-1 beta and iNOS was absent in control (saline treated) but was increased in endotoxin treated animals. In animals treated with endotoxin plus AG (400 mg/kg), expression of iNOS was markedly inhibited whereas there was no effect on expression of TNF-infinity and IL-1 beta. The inhibitory effect of AG was probably dose dependent because a lower concentration of AG (50 mg/kg) showed no change in the expression of iNOS.

Nitric oxide produced by cytokine-activated pulmonary artery smooth muscle cells is cytotoxic to cocultured endothelium

BACKGROUND

We recently demonstrated that rat pulmonary artery smooth muscle (RPASM) generates maximal nitric oxide (NO) when exposed to inflammatory cytokines, such as tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. Our hypothesis is that NO produced by cytokine-stimulated RPASM has local cytotoxic effects on endothelium. Accordingly, we designed a pulmonary smooth muscle and endothelial coculture experiment in which the effects of NO on endothelium can be distinguished from the direct effects of cytokines.

METHODS

RPASM cells were incubated with a mixture of TNF-alpha (500 units/ml) and IFN-gamma (100 units/ml) for 24 hours. This cytokine mixture was then removed and the NO-producing smooth muscle cells were incubated in a coculture transwell system with rat pulmonary artery endothelial (RPAE) cells. Subsequent NO production (as measured by nitrite concentration in cell supernatants), and the number of viable attached endothelial cells were then measured at 48 hours.

RESULTS

RPASM continued to produce large amounts of NO, in the absence of further cytokine stimulation, after a 24-hour exposure to TNF-alpha and IFN-gamma. This RPASM-generated NO decreased the number of viable attached endothelial cells after 24 hour RPASM-RPAE coculture by 57%. The competitive stereospecific inhibitor of inducible NO synthase (iNOS), NG-monomethyl-L-arginine (NMA), returned the inducible NO production to basal levels and reversed the cytotoxic effects on endothelial cells. The number of viable attached endothelial cells returned to control levels.

CONCLUSIONS

The NO produced by cytokine-activated RPASM has local cytotoxic effects on RPAE in coculture. Such NO produced in the vasculature may be a factor in the origin of acute lung injury under conditions of trauma and sepsis.

Ultraviolet radiation-induced production of superoxide radicals by selected antibiotics

The ability of certain drugs and chemicals to induce cutaneous phototoxicity and DNA damage has been attributed to free radical formation during photolysis. In this context we have observed that the synergistic action of commonly used antibiotics and ultraviolet radiation (UVR) exhibited strong superoxide radical (O2-) generation potential in the following order: benzylpenicillin > amphotericin > ampicillin > nystatin > spectinomycin > gentamicin. Commercially available penicillin, nystatin, ampicillin and gentamicin also generated O2- under similar conditions. The results suggest that due precaution are necessary to avoid UVR after the intake of photoreactive drugs.

Ultraviolet-B effects on ocular tissues

The enhancement of UVB on the surface of the earth due to stratospheric ozone depletion may increase the risk of photochemically induced cataract. In this study, changes in the content of certain biological parameters were used as a marker to study ocular toxicity. A significant enhancement in the level of H2O2, LP and Pi, along with the depletion of GSH (antioxidant-defence system) in serum, aqueous humor and lens of albino mice exposed to UVB was observed. The level of Ca++ increased in serum and aqueous humor but decreased considerably in the lens due to increase in UVB exposure. These observations provide further clues to support the involvement of oxidative stress and Ca++ in the events leading to the formation of cataract.

Protection of UV-radiation induced skin toxicity by reactive oxygen scavengers

Although, photoaddition reactions of psoralens with DNA and membrane lipid are regarded as the major photochemical events responsible for skin-photosensitization and photochemotherapeutic properties, their O2-dependent reactive oxygen specie (ROS) generating potential is also responsible for biologic photooxidation reactions and cutaneous phototoxicity. We have investigated the skin-sensitization reactions of psoralen in presence of selected free radical scavengers. The results confirm that sodium azide, DABCO and beta-carotene inhibited considerably the 1O2 generation reactions in a chemical system (determined by monitoring the bleaching of N,N-dimethyl-p-nitrosoaniline in the presence of histidine used as a selective acceptor of 1O2) as well as skin sensitization in vivo (epilated guinea pig skin). These observation suggest that the O2-dependent photodynamic action of psoralen contributes significantly to the development of cutaneous toxicity which can be inhibited by selective scavengers of 1O2.

Photophysical and photobiological properties of 3-carbethoxypsoralen

3-Carbethoxypsoralen (3-CP), a linear tricyclic psoralen, known for its photoreaction with DNA to form monofunctional cyclobutane adducts with pyrimidine bases, was found to produce a highly reactive cytotoxic species, singlet oxygen (1O2) to a greater extent than several other linear psoralens such as psoralen, 8-MOP, 5-MOP or angular psoralens (angelicin). 3-CP also produced superoxide radicals (O2-.) at a rate slower than psoralens in the following order:psoralen > angelicin > 3-CP > 8-MOP > 5-MOP. 1O2 produced by photoactivated 3-CP was found to oxidize tyrosine and Dopa to Dopachrome, and subsequently their conversion to melanin. It also induced photooxidation of 2'-deoxyguanosine. Reactive oxygen species produced by 3-CP also induced lipid peroxidation. The rate of dopachrome formation to promote its conversion to melanin and lipid peroxidation by 3-CP and other linear and angular psoralens and hematoporphyrin derivatives may be related to their skin photosensitizing ability and the rate of 1O2 production. Topically applied 3-CP on hairless mice exposed to UVA radiation was found to be a nonphotocarcinogenic agent in contrast to 8-MOP, which under similar conditions produced a 70% tumour yield (squamous cell carcinoma) in 65 weeks. 3-CP was observed to be a photolabile compound and was converted to a dihydro-form as previously reported by other investigators. The photoconversion of 3-CP to 4',5'-dihydro-3-CP was enhanced under N2, whereas, under O2 atmosphere, lesser degree of photoconversion was observed, thus, indicating that reduction takes place via an anoxic or Type I mechanism. The significance of these observations are discussed in relation to the skin photosensitizing, nonphotocarcinogenic, and photochemotherapeutic potential of 3-CP.

The role of reactive oxygen species in the degradation of lindane and DDT

We have studied the photodegradation reactions of lindane and DDT under sunlight (72 hr) or a solar simulator (2 hr) either directly or in presence of selected photodynamic sensitizers. Direct photolysis did not cause noticeable degradation of the pesticides (below 1% in both the cases). However, addition of benzophenone or rose bengal to the irradiation solution of lindane resulted in 88% and 47% degradation, respectively, under sunlight. Similar experiments carried out with DDT resulted in 89%, 50% and 32% degradation with benzophenone, rose bengal and methylene blue, respectively. All the photosensitizers used for the study have been shown to induce photooxidation reactions by generation of reactive oxygen species. These studies suggest that by employing certain naturally occurring photosensitizers with reactive oxygen generation potential under sunlight, an effective method for safe removal of pesticides and other environmentally persistent agents from the surface of earth can be developed.

Haemolysis by ultraviolet B of red blood cells from different animal species

Photohaemolysis of erythrocytes was studied under ultraviolet B (UVB) light, which emitted radiation predominantly in the 290-320 nm region. Maximum haemolysis was obtained with rat red blood cells (RBCs), followed by human, fish, sheep, pigeon, lizard and frog RBCs. The rate of UVB-induced haemolysis was almost identical to that produced by UVC (200-290 nm), both causing extensive damage to RBCs. On the other hand, natural sunlight or UVA (320-400 nm) caused very little damage to RBCs. The results indicated that exposure to UVB is detrimental to RBCs and photomodification of RBCs is induced even with small increments in UVB level due to stratospheric ozone depletion.

Tryptophan as an endogenous photosensitizer to elicit harmful effects of ultraviolet B

Owing to stratospheric ozone depletion (SOD) the natural flux of ultraviolet B (UVB) radiation (290-320 nm) is likely to increase on the earth surface. In our efforts to identify endogenous chromophores which may absorb significantly in the UVB range and subsequently induce phototoxic reactions, we have observed that tryptophan (Trp) was quite photoreactive under UVB. It enhanced considerably the oxygen-dependent photooxidation of tyrosine (Tyr) to dopachrome, a precursor of melanin. Our data suggest that UVB-sensitized Trp produces singlet oxygen (1O2) and superoxide radicals (O2-.), and these reactive forms of oxygen may contribute to membrane-, cytoplasm- and DNA-damaging effects. In the event of an increasing SOD level, other UVB chromophores may also exhibit similar phototoxic properties to lead to a definitive imbalance between cell life, injury and death.

Membrane damaging potential of photosensitized riboflavin

Riboflavin upon exposure to UV and visible radiations has been shown to produce active oxygen species. The present work deals with erythrocyte membrane as model system to study the damaging potential of photosensitized riboflavin. Membrane preparations (2.5 mg protein/ml) following exposure to sunlight in presence of riboflavin for different time intervals revealed significant inhibition of ATPases, p-nitrophenyl phosphatase and acetylcholinesterase. Considerable increase in lipid peroxidation was caused by the photosensitized riboflavin. Quenching studies using specific scavengers indicated remarkable inhibition. The production and identification of reactive oxygen species by photosensitized riboflavin and their possible involvement in membrane damaging effect has been discussed.