Investigating the Impact of Carbon Nanotube Nanoparticle Exposure on Testicular Oxidative Stress and Histopathological Changes in Swiss albino Mice

Carbon nanotubes (CNTs) possess remarkable properties that make them valuable for various industrial applications. However, concerns have arisen regarding their potential adverse health effects, particularly in occupational settings. The main aim of this research was to examine the effects of short-term exposure to multiwalled carbon nanotube nanoparticles (MWCNT-NPs) on testicular oxidative stress in Swiss albino mice, taking into account various factors such as dosage, duration of exposure, and particle size of MWCNT-NP. In this study, 20 mice were used and placed into six different groups randomly. Four of these groups comprised four repetitions each, while the two groups served as the vehicle control with two repetitions each. The experimental groups received MWCNT-NP treatment, whereas the control group remained untreated. The mice in the experimental groups were exposed to MWCNT-NP for either 7 days or 14 days. Through oral administration, the MWCNT-NP solution was introduced at two distinct dosages: 0.45 and 0.90 μg, whereas the control group was subjected to distilled water rather than the MWCNT-NP solution. The investigation evaluated primary oxidative balance indicators-glutathione (GSH) and glutathione disulfide (GSSG)-in response to MWCNT-NP exposure. Significantly, a noticeable reduction in GSH levels and a concurrent increase in GSSG concentrations were observed in comparison to the control group. To better understand and explore the assessment of the redox status, the Nernst equation was used to calculate the redox potential. Intriguingly, the calculated redox potential exhibited a negative value, signifying an imbalance in the oxidative state in the testes. These findings suggest that short-term exposure to MWCNT-NP can lead to the initiation of testicular oxidative stress and may disrupt the male reproductive system. This is evident from the alterations observed in the levels of GSH and GSSG, as well as the negative redox potential. The research offers significant insights into the reproductive effects of exposure to MWCNTs and emphasizes the necessity of assessing oxidative stress in nanomaterial toxicity studies.

Pharmacognostical evaluation and physiochemical analysis of Salsola Kali as medicinal plant

One of the largest genera Salsola include halophytic plants with therapeutic potential. For the treatment of various ailments, plants of the genus are acclaimed. Salsola kali is an important medicinal plant exhibiting specific phytochemical and biological makeup that is frequently overlooked. The current study aimed at the pharmacognostical evaluation of leaves and stem of Salsola kali to ensure the purity, quality, and efficacy of this valuable medicinal species. For the identification, evaluation and standardization of diagnostic attributes of intact and powdered material of Salsola kali leaves and stem, various methods including organoleptic, macroscopic, microscopic, and physicochemical analysis were employed. The plant was identified to possess significant characteristics with a view to authenticate drug. Light Microscopy (LM) and Scanning Electron Microscopy (SEM) of aerial parts of Salsola kali manifested specialized anatomical features essential for the adaptability in dry-saline environment. Upon quantitative pharmacognostic analysis of powder of leaves and stem, the moisture content of 1.3% and 11.1%, respectively was found. The total ash (%) in leaves and stem was computed to be 65.95 and 85.3, respectively. The water soluble and alcohol soluble extractive values (%) were computed to be 79.38 and 75.4 in leaves and 78.0 and 76.8 in stem, respectively. The swelling index (cm) in leaves and stem was enumerated to be 0.8 and 0.5. The current study will be helpful in the quality check and authentication of various parts of Salsola kali that can be used as principal component of herbal medicine formulation. Based on various microscopic analyses, that is, Light Microscopy and Scanning Electron Microscopy, the detailed description and valuable information on Salsola kali, a medicinal plant, has been provided. The present study can make a significant contribution in the literature as the findings may contribute to the determination of purity of Salsola kali for future perspectives.

Water Quality Index and Human Health Risk Assessment of Drinking Water in Selected Urban Areas of a Mega City

The present study was conducted to evaluate the quality of drinking water and assess the potential health hazards due to water contaminants in selected urban areas of Lahore, Pakistan. Water samples were collected from ten sites and analyzed for different physico-chemical parameters including turbidity, color, pH, total dissolved solids (TDS), nitrates, fluoride, residual chlorine, and total hardness. Additionally, heavy metal (arsenic) and microbial parameters (E. coli) were also determined in the water samples. Drinking water quality evaluation indices, including the water quality index (WQI) for physico-chemical and biological parameters and human health risk assessment (HHRA) for heavy metal were estimated using the analytical results of the target parameters. It was found in most of the areas that the levels of arsenic, fluoride, TDS, and residual chlorine were higher than those recommended by the National Environmental Quality Standard (NEQS) and World Health Organization (WHO) guidelines. In addition to the physico-chemical parameters, microbial content (E. coli) was also found in the drinking water samples of the selected areas. Statistical analysis of the results indicated that levels of target parameters in drinking water samples are significantly different between sampling sites. The WQI for all physico-chemical and microbial parameters indicated that drinking water in most of the areas was unfit and unsuitable (WQI > 100) for drinking purposes except for the water of Bhatti Gate and Chota Gaon Shahdara with a WQI of 87 and 91, respectively. Drinking water in these areas had a very poor WQI rating. According to HHRA, drinking water from the selected sites was found to be of high risk to children and adults. The carcinogenic risk of arsenic indicated that all samples were of high risk to both adults and children (4.60 and 4.37 × 10^-3, respectively). Regular monitoring of drinking water quality is essential, and proactive measures must be implemented to ensure the treatment and availability of safe drinking water in urban areas.

Scanning electron microscopy for identification of local strain of Aspergillus Parasiticus and its larvicidal efficacy against Aedes Aegypti and non-target toxicity testing on fingerlings of Hypophthalmichthys Molitrix

Scanning electron microscopy proved to be helpful in identification of Aspergillus parasiticus. A. parasiticus has a worldwide occurrence with high entomopathogenic efficacy against Aedes aegypti. However, assessment of pathogenic effects of entomopathogenic fungi on non-target organisms is required to evaluate its use as bio control agent. Aim of the present research is to study the parricidal activity of the local strain of A. parasiticus (MK371710) against A. aegypti and its toxicity assessment against aquatic model organism Hypophthalmichthys molitrix. A. parasiticus was isolated from the soil of Jallo Park, Lahore. The larvicidal effect of A. parasiticus was evaluated against fourth instar larvae of A. aegypti. Hundred percent of mortality of larvae was observed after exposure to 1 × 10⁷ conidia/ml of fungal suspension after 72 h post treatment. The LC₅₀ value of A. parsiticus in 24 h post treatment and 48 h post treatment was recorded as 1.0 × 10⁷ conidia/ml 2.99 × 10⁵ conidia/ml, respectively. However, an in-depth understanding safety to non-target organisms is necessary, if we are to properly control the action of these entomopathogenic fungi under natural conditions. For the toxicity assessment fingerlings of H. molitrix were exposed to conidial suspensions of A. parasiticus. Eye pop (64%), fin hemorrhage (33%), and scale infection (30%) were the major morphological effects observed during the study. Results reveal that although A. parasiticus is highly pathogenic to dengue vector but also have significant effects on organisms other than insects and its application as biological control agent requires safety considerations.

SEM and XRD for removal of heavy metals from industrial wastewater and characterization of chicken eggshell

Heavy metal toxicity due to industrial wastewater has been a threat to the environment for the past many decades, especially in developing countries. Electroplating Industry wastewater containing heavy metals can become a serious environmental pollutant if not treated appropriately. Present study investigated the removal of nickel and chromium ions from electroplating wastewater using calcined hen eggshells because of it high removal capability, little cost and easy approachability. Characterization of the adsorbent such as proximate analysis, surface charge, X-ray diffraction, and surface area was done prior to adsorption process. Batch adsorption experiment was performed to study the effect of different parameters such as adsorbent dose, contact time, temperature, and pH for adsorbent. Removal percentage of both heavy metals was checked by using calcined eggshell as adsorbent. Comparison was made between nickel and chromium to identify the most effective removal efficacy. It was concluded that utilization of natural waste was found suitable, easier, cost operative and environmental approachable for removal of heavy metals from industrial wastewater.

A comparative assessment of air pollutants of smog in wagah border and other sites in Lahore, Pakistan

Smog has become the fifth season of Pakistan especially in Lahore city. Increased level of air pollutants (primary and secondary) are thought to be responsible for the formation of smog in Lahore. Therefore, the current study was carried out for the evaluation of air pollutants (primary and secondary) of smog in Wagah border particularly and other sites (Jail road, Gulburg) Lahore. For this purpose, baseline data on winter smog from March to December on primary and secondary air pollutants and meteorological parameters was collected from Environmental Protection Department and Pakistan Meteorological Department respectively. Devices being used in both departments for analysis of parameters were also studied. Collected data was further statistically analyzed to determine the correlation of parameters with meteorological conditions and was subjected to air quality index. According to results, PM 10 and PM 2.5 were found very high above the NEQS. NOx concentrations were also high above the permissible limits whereas SO2 and O3 were found below the NEQS thus have no roles in smog formation. Air Quality Index (AQI) of pollutants was PM 2.5(86-227), PM 10 (46-332), NOx (26-110), O3 (19-84) and SO2 (10-95). AQI of PM 2.5 remained between moderate to very unhealthy levels. AQI of PM 10 remained between good to hazardous levels. AQI of NOx remained between good to unhealthy for sensitive groups' levels. AQI of O3 and SO2 remained between good to moderate levels. Pearson correlation showed that every pollutant has a different relation with different or same parameters in different areas. It is concluded from the present study that particulate matter was much more responsible for smog formation. Although NOx also played role in smog formation. So there is need to reduce sources of particulate matter and NOx specifically in order to reduce smog formation in Lahore.

Identification of locally isolated entomopathogenic Fusarium species from the soil of Changa Manga Forest, Pakistan and evaluation of their larvicidal efficacy against Aedes aegypti

Dengue fever vectored by the mosquito Aedes aegypti is one of the most rapidly spreading insect-borne diseases. Current reliance of dengue vector control is mostly on chemical insecticides. Growing insecticide resistance in the primary mosquito vector, Aedes aegypti, limits the effectiveness of vector control through chemical insecticides. These chemical insecticides also have negative environmental impacts on animals, plants and human health. Myco-biocontrol agents are naturally occurring organisms and are found to be less damaging to the environment as compared to chemical insecticides. In the present study, entomopathogenic potential of local strains of fungi isolated from soil was assessed for the control of dengue vector. Local fungal isolates presents better alternative to introducing a foreign biocontrol strain, as they may be better adapted to environmental conditions of the area to survive and may have more entomopathogenic efficacy against target organism. Larvicidal efficacy of Fusarium equiseti and Fusarium proliferatum was evaluated against Aedes aegypti. Local strains of F. equiseti (MK371718) and F. proliferatum (MK371715) were isolated from the soil of Changa Manga Forest, Pakistan by using insect bait method. Larvicidal activity of two Fusarium spp. was tested against forth instar larvae of A. aegypti in the laboratory, using concentrations 105, 106, 107 and 108 conidia /ml. LC50 values for F. equiseti after 24h, 48h, 72h and 96h of exposure were recorded as 3.8x 108, 2.9x107, 2.0x107, and 7.1x106 conidia /ml respectively while LC50 values for F. proliferatum were recorded as 1.21x108, 9.6x107, 4.2x107, 2.6x107 conidia /ml respectively after 24h, 48h, 72h and 96h of exposure. The results indicate that among two fungal strains F. equiseti was found to be more effective in terms of its larvicidal activity than F. proliferatum against larvae of A. aegypti.

Low-temperature health hazards among workers of cold storage facilities in Lahore, Pakistan

BACKGROUND

Cold storage facilities are the most common workplaces that produce artificially cold work environments and are associated with different adverse effects on human health, work productivity and the occurrence of accidents and injuries. The aim of this study was to measure the antagonistic health effects on workers, so that common factors causing abnormal symptoms could be determined, and to gather basic information to monitor the associated health risks from the exposure to cold work environments.

MATERIAL AND METHODS

A cross-sectional analytical study was conducted to investigate the occurrence of cold-related adverse health effects, musculoskeletal symptoms, skin problems, injuries, respiratory illnesses, general hygiene and occupational environment related to cold indoor workplaces, using the <i>Standardized Nordic Questionnaire</i>. A total of 200 subjects took part in this study, including 100 exposed and 100 unexposed to cold environments. A 1-way analysis of variance (ANOVA) and a t-test were applied to measure statistical differences and to differentiate the cases where variations occurred, using SPSS 16.

RESULTS

The study revealed that a longer and constant exposure to extremely cold indoor work environments significantly increased (p <0.001) the cold-related symptoms and musculoskeletal disorders which ultimately reduced (p <0.01) the efficiency, effectiveness, performance and work ability of the exposed workers.

CONCLUSIONS

The study disclosed various adverse cold-related complaints of the studied subjects who were exposed to extreme cold conditions during a maximum number of working hours. The most consistent problems were related to musculoskeletal discomfort, skin problems and respiratory abnormalities. Med Pr. 2020;71(1):1-7.

Anti-oxidative and anti-proliferative activities of extracted phytochemical compound thymoquinone

OBJECTIVE

To evaluate the anti-oxidant and anti-proliferative potential of Thymoquinone extracted from the essential oil of indigenous herbs of Nigella sativa and Thymus vulgaris.

METHODS

Extraction and quantification of Thymoquinone was carried out in July, 2017 in Department of Environmental Science, Lahore College for Women University (LCWU), Lahore. Thymoquinone was extracted from seeds of Nigella Sativa and aerial parts of Thymus vulgaris by employing soxhlet extraction with 1:4 ratios of nhexane and methanol. High Performance Liquid Chromatography was used to quantify Thymoquinone from the methanolic extracted oil of sample by applying calibration curve method. Extracted Thymoquinone was identified by sample peaks obtained at retention time were compared with peak of standard Thymoquinone at respective time. The Thymoquinone obtained from both samples was then subjected to Fourier-transform infrared spectroscopy for confirmation by identifying its functional groups. Anti-oxidant activities of both samples were measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric Reducing Antioxidant Power (FRAP) assay in Department of Environmental Science, LCWU. In-vitro anti-proliferative activities of extracted Thymoquinone were evaluated in HeLa cell cancer lines by cell proliferations Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay in Department of Microbiology, University of Veterinary and Animal Sciences (UVAS), Lahore. SPSS 18 and Graph pad prism 18 was used for data analysis.

RESULTS

Soxhlet extraction with solvents ratios yielded 48.92% oil from Nigella sativa and 23.2 % from Thymus vulgaris. High Performance Liquid Chromatography peak of standard Thymoquinone was measured at retention time of 5.5 min which was then compared with the peak obtained from both samples at the similar retention time. The extracted Thymoquinone from both samples were quantified by calibration curve method showing 614.25 mg/L from Nigella sativa and 548.86 mg/L from Thymus vulgaris. The two anti-oxidant assays of both samples compared with standard Thymoquinone showed significant scavenging activities in dose amount manner. Cell proliferation of HeLa cancer significantly decreased with dose response manner (p<0.01), showing highest cell death in high concentration of Thymoquinone. Inhibitory concentration 50 (IC50) of cancer cell line treated with Nigella sativa oil was 0.5 μM and Thymus vulgaris was 18 μM compared to standard Thymoquinone, showing Inhibitory concentration50 (IC50) of 6 μM using Graph pad prism v.8.0.

Conclusion

Both Nigella sativa and Thymus vulgaris were found to be the best source of Thymoquinone as chemotherapeutic drug expressed potent anti-oxidant and anti-proliferative activities.

Occupational health surveillance: pulmonary function testing and oxidative stress among photocopying workers in Pakistan

BACKGROUND

The photocopying occupation contributes to various health issues in workers. Elevated levels of oxidative stress have been found to be associated with respiratory problems in occupational workers. The intention of the current research is to evaluate the association between the pulmonary function parameters, a biomarker of oxidative stress, and the photocopying occupation in Lahore, Pakistan.

MATERIAL AND METHODS

The study was performed on a group of photocopying operators (N = 100) and a control group (N = 100). A structured questionnaire was developed to gather the demographic attributes. Lung function testing was done with the spirometer. The blood lipid peroxides level, as thiobarbituric acid reactive substances (TBARS), was assessed spectrophotometrically.

RESULTS

A statistically significant reduction was found in the pulmonary function parameters as compared to the control group. In the study group, the prevalence of respiratory symptoms, including cough (31%), sneezing (18%), wheezing (9%) and breathing issues (19%), was high as compared to the control group. A significantly higher plasma TBARS concentration was observed in the photocopying workers. A negative correlation prevailed between FVC (-0.081), FVC% predicted (-0.038) and FEV1 (-0.043), and the duration of exposure.

CONCLUSIONS

The study showed that the occupational exposure could have a significant effect on the normal pulmonary function and the oxidative potential of well-being. The profound emissions in the vicinity of photocopying centers may be responsible for the variations in the pulmonary function parameters and oxidative stress. Med Pr. 2019;70(4):403-10.

Respiratory and physical ailments correlated with occupational exposure among welders in Pakistan

Disruption of normal respiratory function is associated with occupational disorders. Exposure to welding fumes on long term basis affects the lung function of the workers and prompts allergic responses. Therefore, the aim of the study was to manifest the association of exposure to welding fumes and respiratory complications with reference to the undermining of normal lung function and respiratory symptoms. A cross sectional study was conducted in different areas of Lahore in 2016. A comparison was made among welders on the basis of lung function and other physical ailments. Questionnaire survey was performed along with the computation of lung function by using spirometer. Data was statistically analyzed by using analysis of variance (ANOVA). The study confirmed a statistically highly significant decline in FVC, FEV1, FEF 25-75%, PEFR and FEV1/FVC ratio among different types of welders. The current study expressed that occupational exposure to welding fumes can considerably distress the lung function. The application of preventive measures is required to solve the health related questions for welders.

Cytogenetic damage in the buccal cells of photocopying workers in Lahore, Pakistan

OBJECTIVE

To assess the genotoxic effects associated with workers in relation to the emissions at photocopying centres.

METHODS

This case-control study was conducted at the Lahore College for Women University, Lahore, Pakistan, from August to November 2015, and comprised photocopying operators and controls. Micronuclei and other nuclear abnormalities in exfoliated buccal cells were analysed. A structured questionnaire was designed and interviews were conducted face-to-face. Statistical analysis was conducted to evaluate the significance of differences.

RESULTS

Of the 200 participants, there were 100(50%) in each group. There were 24(24%) smokers and 76(76%) non-smokers among the controls compared to 29(29%) smokers and 71(71%) non-smokers among the cases. The mean age was 31.08±10.97 years and 28.19±7.58 years in the controls and the cases, respectively. The frequency of deoxyribonucleic acid damage and cell death parameters was high in photocopying operators compared to the controls (p<0.05). Positive correlation was observed between work span and the frequency of deoxyribonucleic acid damage (r=0.226) and cell death parameters (r=0.115). Smoking was positively associated with the frequencies of deoxyribonucleic acid damage (r=0.65) and cell death parameters (r=0.37). The differences were statistically significant (p<0.001).

CONCLUSIONS

A highly significant difference was observed in deoxyribonucleic acid damage and cell death of workers associated with photocopy profession.

Cross-sectional study on the endotoxin exposure and lung function impairment in the workers of textile industry near Lahore, Pakistan

OBJECTIVE

To examine the effects of airborne endotoxin on lung function impairment in exposure-response relationships among the workers of textile industry.

METHODS

The cross-sectional study was conducted at Lahore College for Women University, Lahore, Pakistan, from January to August 2014, and comprised textile mill workers. The participants were divided into exposed and control groups. A questionnaire was used to ask workers about the potential adverse health effects of their occupation. The pulmonary function test was carried out by spirometer. Endotoxin levels in the samples were determined using the key quality characteristics limulus amebocyte lysate. The data was analysed to determine the correlation between the endotoxin exposure duration and pulmonary function test parameters.

RESULTS

There were 200 subjects subdivided into 100 each inexposed and control groups. Overall, 160(80%) were not aware of safety measures and the remaining 40(20%) were partially practising. Changes in pulmonary function due to endotoxin exposure showed decreased force vital capacity, flow rate and peak expiratory flow parameters significantly different (p<0.05, p<0.001). The endotoxin concentration was between 12EU/m3 and 300EU/m3. Airborne endotoxin concentrations in textile plants exceeded the Dutch health-based guidance limit of 90EU/m3 and was associated with respiratory health effects.

CONCLUSIONS

Prolonged exposure to airborne endotoxin caused constant lung impairment. Proper safety measures should be adopted to avoid the inhalation of cotton dust.

Preliminary development of a revised version of the School Climate Measure

The School Climate Measure (SCM) was developed and preliminarily validated in 2010 and extended upon in 2013 in response to a dearth of psychometrically sound school climate instruments. This study sought to further validate the SCM on a large diverse sample of Arizona public school adolescents (N = 1,643) with two new domains. The eight original SCM domains (Positive Student-Teacher Relationships, School Connectedness, Academic Support, Order and Discipline, Physical Environment, Social Environment, Perceived Exclusion, and Academic Satisfaction) and two newly developed domains (Parental Involvement and Opportunities for Student Engagement) were subjected to psychometric analysis. The sample was randomly split into exploratory and confirmatory halves and subjected to factor analytic and structural equation modeling techniques. Factor analysis confirmed a 10-factor solution (loadings with absolute values > .40). Item factor loadings ranged from .47 to .95. Coefficient alphas ranged from .70 to .92. Fit statistics indicated a good fitting model (χ2 = 1452.67 [df = 734, p < .01], CFI = .94, TLI = .93, RMSEA = .039). This process eliminated some original SCM items, but the overall SCM increased only from 39 to 42 items with the newly developed domains. This investigation adds to the existing evidence for the SCM and offers support for a more comprehensive version of the SCM. The addition of the Parental Involvement and Opportunities for Student Engagement domains should further enhance the usefulness of the SCM. The SCM can facilitate data-driven decisions and may be incorporated into evidenced-based processes designed to improve important student learning and well-being outcomes.

Psychometric support of the school climate measure in a large, diverse sample of adolescents: a replication and extension

BACKGROUND

The School Climate Measure (SCM) was developed and validated in 2010 in response to a dearth of psychometrically sound school climate instruments. This study sought to further validate the SCM on a large, diverse sample of Arizona public school adolescents (N = 20,953).

METHODS

Four SCM domains (positive student-teacher relationships, academic support, order and discipline, and physical environment) were available for the analysis. Confirmatory factor analysis and structural equation modeling were established to construct validity, and criterion-related validity was assessed via selected Youth Risk Behavior Survey (YRBS) school safety items and self-reported grade (GPA) point average.

RESULTS

Analyses confirmed the 4 SCM school climate domains explained approximately 63% of the variance (factor loading range .45-.92). Structural equation models fit the data well χ(2) = 14,325 (df = 293, p < .001), comparative fit index (CFI) = .951, Tuker-Lewis index (TLI) = .952, root mean square error of approximation (RMSEA) = .05). The goodness-of-fit index was .940. Coefficient alphas ranged from .82 to .93. Analyses of variance with post hoc comparisons suggested the SCM domains related in hypothesized directions with the school safety items and GPA.

CONCLUSIONS

Additional evidence supports the validity and reliability of the SCM. Measures, such as the SCM, can facilitate data-driven decisions and may be incorporated into evidenced-based processes designed to improve student outcomes.

Adolescent boys' experiences of first sex

There are limited contextual data regarding first sexual experiences of younger adolescent men. Yet these data that are needed to inform sexually-transmitted-infection and early-fatherhood-prevention efforts, particularly in lower-income communities. Using qualitative methods, 14 adolescent men (ages 14-16, all low-income, most African American) from a mid-sized US city were asked about relationships and sexual experiences in a one-hour face-to-face semi-structured interview, with two follow-up interviews at six- to nine-month intervals. Story-telling was encouraged. Descriptions of first sex were identified and then analysed for narrative structure and shared concepts. The dominant narrative of first sex proceeded through three steps: (1) preparation, which involved identification of a sexualised space, mentoring and pre-planning, (2) the event, which involved looking for cues indicating sexual interest and consent from a female partner, feelings of fear/nervousness and first sex itself and (3) afterwards, which involved a return to prior activities, minimal verbal exchange and a general positive feeling, sometimes accompanied by later disappointment. Mentorship, initiation by the female and idealising sex as a romantic experience, played important roles in constructing the context of first sex. These factors should be incorporated in harm-reduction interventions for young men in similar contexts.

Effects of background field-of-view and depth-plane on the oculogyral illusion

This study examined the effects of background field-of-view and depth plane on the oculogyral illusion. Seven subjects viewed a stationary fixation stimulus during the postrotatory interval following a 45-sec constant-velocity chair rotation. The duration of the illusory movement of the fixation stimulus during the postrotatory interval was measured, along with the duration of the illusion of whole-body rotation (known as the somatogyral illusion) and the duration of the subject's slow-phase vestibular nystagmus. Subjects viewed the fixation stimulus by itself in a No-background condition or when surrounded by six background fields formed by the combination of two fields-of-view (35 degrees and 115 degrees) and three depth-planes (near, coplanar, and far). The different background fields inhibited the oculogyral illusion relative to the No-background condition but did not differ statistically from each other. The somatogyral durations better matched the oculogyral ones than did nystagmus decay, especially when a background field was present. These results suggest that the oculogyral illusion is more related to the experience of whole-body rotation than to oculomotor mechanisms and that the inhibitory effect of a background scene is only modestly affected by its field-of-view and depth plane.

Bioassay of cadmium and its effect on differential distribution of dehydrogenases in different brain regions in Labeo rohita (HAM)

The sublethal effect of cadmium on the specific activities of lactic, malic and succinic dehydrogenases in different brain regions in Labeo rohita (HAM) was assessed with reference to acute, chronic and recovery conditions. Cadmium enhanced succinic, malic and lactic dehydrogenases to a marked extent in the cerebrum from 0 to 12 h exposure. However, a subsequent fall of the above enzymes in some regions was recorded from 12 to 24 h. In chronic studies, the greatest decrease in succinic dehydrogenase was noted in the cerebrum (0 to 15 days) and the least reduction in the cerebellum (30 to 45 days) in comparison with malic and lactic dehydrogenase. In recovery studies an optimum rise in lactic, malic and succinic dehydrogenase was found in the cerebrum (30-45 days). In general, cadmium accumulation was highest in the cerebrum (12 h and 15 days) and least in the cerebellum (24 h and 45 days). This was markedly above the safety level in acute and chronic situations.

Chromatic content of spectral lights

Using three novel formats, we compare four estimates of the spectral sensitivity of the opponent stage channels: a Linear Model, Jameson and Hurvich's [Journal of the Optical Society of America, 45, 546-552 (1955)] hue cancellation sensitivities, Gordon and Abramov's [Optical Society of America Technical Digest Series, 15, 12-15 (1987)] hue scaling, and hue matching. The three formats are: the spectrum locus in the opponent equiluminant plane, null lines in the CIE XYZ chart and response functions for unique hues. All sensitivities show departures from the Linear Model and from each other. Relative to the model, common features of all estimates are that violets are compressed; long-wavelength reds are amplified; the redness component of violet lights is greatly attenuated; and saturation of violet stimuli is underestimated.

Mercury concentrations in canned and fresh fish and its accumulation in a population of Port Moresby residents

Five varieties of canned fish and hair specimens from 243 subjects in Port Moresby have been analysed for organic and total mercury. The mean concentrations of total mercury in the canned fish were 0.45 mg/kg for tuna, 0.21 mg/kg for salmon, 0.17 mg/kg for mackerel, 0.08 mg/kg for sardines and 0.04 mg/kg for pilchard, based on the weight of the fish. The mean hair concentration was 2.1 mg/kg, the standard deviation 1.8 mg/kg and the range 0.15 to 14.4 mg/kg. The total mercury levels in hair were significantly higher for coastal people than for non-coastals. Although this is probably due to the greater fish intake of the coastal people, no significant correlation was found between fish consumption and hair mercury levels.

Methylmercury in human hair: a study of a Papua New Guinean population exposed to methylmercury through fish consumption

The mean methylmercury concentration in hair of a Papua New Guinean population was 15.5 micrograms/g (range = 3.2-50.5 micrograms/g). Nearly all individuals consumed fish 2 to 3 times daily. In contrast, the mean methylmercury concentration in hair of a nearby control group who consumed a similar amount of fish was 6.4 micrograms/g (range = 0.62-25.7 micrograms/g). A control group that consumed fish much less frequently had a mean methylmercury concentration in hair of 2.4 micrograms/g (range = 0.33-9.0 micrograms/g). No statistically significant variations in methylmercury concentrations in hair were found with sex or age within any of the three populations.

Elevated mercury levels in people from Lake Murray, Western Province

The people of Lake Murray, Western Province, Papua New Guinea are chronically exposed to methylmercury through fish consumption. In a study of 114 volunteers from the area, the mean methylmercury concentration in hair was 15.5 mg/kg (range 3.2--50.5). The main source of methylmercury is barramundi (Lates calcarifer) caught in the Lake. For nearby control groups having similar and much lower levels of fish consumption, the mean methylmercury levels in hair were 6.4 mg/kg (range 0.62--25.7) and 2.4 mg/kg (range 0.33--9.0) respectively. No significant correlations were found between methylmercury concentrations in hair and age or sex in any of the three populations.