Increase in axial length of the macaque monkey eye after corneal opacification.
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The cornea of one eye was opacified in two young macaque monkeys by multiple stromal injections of a suspension of polystyrene particles (latex). Ultrasound measurements showed that the eye with opaque cornea grew at a faster rate, so that after 1 year it was more than 1 mm longer than the normal eye. This difference in axial length was due to elongation of the posterior segment, since lens thickness, depth of anterior chamber, and corneal curvature were identical in both eyes. At histological examination, no pathological changes were observed in the anterior segment of the latex-injected eye except for a scant vascularization of the corneal opacity. The result of this experiment demonstrates that opacification of the corneal has effects on axial length similar to, although less marked than, those on lid fusion and therefore supports our previous conclusion that the myopia caused by lid fusion is triggered by the abnormal visual impact and involves central visual pathways. (+info)
Assessment of 1,3-butadiene exposure in polymer production workers using HPRT mutations in lymphocytes as a biomarker.
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1,3-Butadiene (BD), which is used to make styrene-butadiene rubber, is a potent carcinogen in mice and a probable carcinogen, associated with leukemia, in humans. We have previously used HPRT mutation as a biomarker to evaluate exposures to BD in a monomer production plant. We now report on a study of 49 workers in a styrene-butadiene rubber plant in which we used the concentration of the BD metabolite 1,2-dihydroxy-4-(N-acetylcysteinyl-S)-butane (M1) in urine as a biomarker of exposure and the frequency of HPRT variant (mutant) lymphocytes (Vf) as a biomarker of effect. Workers were assigned to high- and low-exposure groups based on historical information about work areas and jobs. Personal exposure to BD for one work shift was measured using a passive badge dosimeter. Each participant provided a urine specimen and blood sample at the end of the work shift and completed a questionnaire providing information on lifestyle, health, and work activities. The average BD exposures in the high- and low-exposure groups were significantly different, even after excluding two extreme values, (high 1.48 ppm; low 0.15 ppm, p < 0.002). This study was done in 1994 and 1995 before the establishment, in 1996, of the new permissible exposure limit of 1 ppm. Both the mean M1 and the HPRT Vf were more than three times greater in the high-exposure group than in the low-exposure group (p < 0.0005). The three end points correlated with each other, with sample correlation coefficients between 0.4 and 0.6. The correlations among BD exposure and the biomarkers of internal exposure and genotoxicity suggest that occupational exposure to BD, in the range of 1-3 ppm, may be associated with adverse biological effects. (+info)
Cancer mortality in U.S. counties with plastics and related industries.
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Counties in the United States have been identified with chemical establishments whose primary manufacturing processes use vinyl chloride. Site-specific cancer mortality comparisons have revealed an excess of multiple myeloma in males associated with two of the manufacturing categories, synthetic rubber and synthetic fibers. A causal relationship between these manufacturing categories and multiple myeloma could not be established. An industry-based assessment of the occupational contribution to this excess is needed to evaluate the etiologic importance of this relationship. (+info)
Socioeconomic profile and nutritional status of children in rubber smallholdings.
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This paper will present the socioeconomic profile and nutritional status of children aged 1-6 years in the rubber smallholdings of Peninsula Malaysia. A total of 323 households were involved in this study. The sociodemographic data were obtained through interviews with heads of households using a set of questionnaires. Anthropometric measurements were taken from 506 children aged 1-6 years from these households. The weight and height of the children were compared with the reference values of the National Center for Health Statistics (NCHS) and the nutritional status was classified based on the recommendations of WHO. The average age of the fathers was 39.9+/-8.6 years and 34.4+/-7.0 years for the mothers. The mean household size was 6.67+/-2.27. The majority (49.7%) of the heads of households received 4-6 years of formal education and 7.9% received no formal education. Based on the monthly per capita income, 24.0% were found to be in the hardcore poor category, 38.3% fall into the poor category and 37.7% in the above poverty income group. The prevalence of stunting and underweight among children between the ages of 1-6 years were highest among children from the hardcore poor, followed by the poor category and above the poverty line income group. Wasting was present in all income groups, with a prevalence of 4.2% found among the hardcore poor, 9.4% among the poor group and 8.4% in the above poverty income group. The Pearson Product Moment Correlation showed significant relationships between household total income and height-for-age (r = 0.131, P = 0.05) and weight-for-age (r = 0.127, P = 0.05). There were also significant correlations between monthly per capita income with height-for-age (r = 0.16, P < 0.01) and weight-for-age (r = 0.13, P < 0.05). The acreage of land utilised was correlated with height-for-age (r = 0.11, P < 0.05), weight-for-age (r = 0.17, P < 0.05) and weight-for-height (r = 0.16, P < 0.05). However, stepwise multiple regression analysis indicated that the predictor of height-for-age was monthly per capita income (R2 = 0.03, P < 0.01) and acreage of land utilised was a predictor for weight-for-age (R2 = 0.03, P < 0.01) and weight-for-height (R2 = 0.01, P < 0.01). Because income and acreage of land utilised have been shown to be associated with nutritional status, it is recommended that intervention programs that focus on generation of income and diversification of land utilisation should be undertaken. A multidiscipline approach involving the family, community and government agencies should be applied to any type of intervention program. (+info)
Rubber band ligation of haemorrhoids in the out-patient clinic.
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Rubber band ligation (RBL) is an effective treatment for symptomatic haemorrhoids but carries significant morbidity. We performed a prospective study of 98 consecutive patients treated by RBL in the out-patient clinic. Immediate, intermediate (within 2 weeks) and late (within 2 months) complications were recorded. Immediate complications occurred in 66 (67.3%) patients. Pain was the predominant symptom in 50 patients (51%). Fifteen (15.3%) patients had vasovagal attacks and 1 (1%) had bleeding. Twenty-five patients (25.5%) were unable to perform normal activities on the day of RBL. One patient needed hospital admission for control of pain. Seventy four (75.5%) patients would have RBL if they needed further treatment for haemorrhoids. Symptomatic cure was achieved in 71 patients (72.4%). RBL is an effective treatment but with significant complications. Patients should be adequately warned, especially of pain and vasovagal attacks. (+info)
Gordonia westfalica sp. nov., a novel rubber-degrading actinomycete.
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A cis-1,4-polyisoprene-degrading bacterium (strain Kb2T) was isolated from foul water taken from the inside of a deteriorated automobile tyre found on a farmer's field in Westfalia, Germany. The strain was aerobic, Gram-positive, exhibited orange smooth and rough colonies on complex nutrient agar, produced elementary branching hyphae that fragmented into rod/coccus-like elements and showed chemotaxonomic markers which were consistent with its classification within the genus Gordonia, i.e. the presence of mesodiaminopimelic acid, arabinose and galactose in whole-cell hydrolysates (cell-wall chemotype IV), N-glycolylmuramic acid in the peptidoglycan wall, a fatty-acid pattern composed of unbranched saturated and monounsaturated fatty acids plus tuberculostearic acid, mycolic acids comprising 56-60 carbon atoms and MK-9(H2) as the only menaquinone. The 16S rDNA sequence of strain Kb2T was found to be most similar to the 16S rDNA sequences of the type strains of Gordonia alkanivorans (DSM 44369T) and Gordonia nitida (KCTC 0605BPT). However, DNA-DNA relatedness data showed that strain Kb2T ( =DSM 44215T NRRL B-24152T) could be distinguished from these two species and represented a new species within the genus Gordonia, for which the name Gordonia westfalica is proposed. (+info)
Exposure related mutagens in urine of rubber workers associated with inhalable particulate and dermal exposure.
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AIMS: To determine the relation of the inhalation and dermal exposure routes and mutagenic activity in the urine of rubber workers (n = 105). METHODS: Mutagenic activity of ambient total suspended particulate matter (TSPM), surface contamination wipes, and Sunday and weekday urine samples was assessed with S typhimurium YG1041 in the presence of a metabolic activation system. Each subject was grouped into one of two exposure categories for dermal exposure (high (>/=25 revertants/cm(2)), low (<25 revertants/cm(2))) based on the mutagenic activity detected on likely skin contact surfaces and into two airborne mutagenic exposure categories (high (>/=210 revertants/m(3)), low (<210 revertants/m(3))). The potential influence of skin aberrations and acetylation status (NAT2) on urinary mutagenicity levels was also evaluated. RESULTS: A non-significant increase of +1605 revertants/g creatinine in urinary mutagenicity during the workweek relative to levels observed on Sunday was observed for the total population. Subsequent multivariate regression analyses, with the subjects' weekday urinary mutagenicity levels as the dependent variable, revealed associations with environmental and mainstream tobacco smoke exposure, with the level of mutagenic contamination on surfaces with which the subjects had likely contact, with the subjects' inhalable particulate exposure level, with observed mild skin aberrations, and when the subjects had a slow acetylation phenotype. Similar associations, although weaker were observed with Sunday urinary mutagenicity levels as well, except for the association with slow acetylation phenotype. Based on measured exposure levels it could be estimated that a high potential for exposure to surface contamination with mutagenic activity increased weekday urinary mutagenicity by about 62% when compared to low exposed workers, while high inhalable particulate exposure levels increased weekday urinary mutagenicity levels by about 21%. Subjects with mild skin aberrations had an additional, non-significant, increase in weekday urinary mutagenic activity compared to subjects without any skin aberrations. DISCUSSION: Results suggest that the dermal exposure route may contribute more to the level of genotoxic compounds in urine of rubber workers than the inhalation route. Although the study was limited in size, the results warrant further investigation in the importance of and ways to effectively control the dermal exposure route in the rubber industry. (+info)
The micromorphology and protein characterization of rubber particles in Ficus carica, Ficus benghalensis and Hevea brasiliensis.
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Rubber biosynthesis takes place on the surface of rubber particles. These particles are surrounded by a monolayer membrane in which the rubber transferase is anchored. In order to gain better insight into whether rubber particles from different plant species share common structural characteristics, the micromorphology of rubber particles from Ficus carica, Ficus benghalensis, and Hevea brasiliensis was examined by electron microscopy. Rubber particles of all three species were spherical in shape, and the size of rubber particles of H. brasiliensis was much smaller than those of F. carica and F. benghalensis. In addition, investigations were undertaken to compare the cross-reactivity of the antibody raised against either the H. brasiliensis small rubber particle protein (SRPP) which is suggested to be involved in rubber biosynthesis, or the cis-prenyltransferase (CPT) which has an activity similar to rubber transferase. Both western analysis and TEM-immunogold labelling studies showed that rubber particles of F. carica and F. benghalensis do not contain the SRPP. None of the rubber particles in F. carica, F. benghalensis and H. brasiliensis contained the CPT, suggesting that the CPT itself could not catalyse the formation of high molecular weight rubber. These results indicate that rubber particles in the three different plant species investigated share some degree of similarity in architecture, and that the SRPP and CPT themselves are not the core proteins necessary for rubber biosynthesis. (+info)