Adsorption studies in a synthetic rubber latex-ovalbumin system.
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1. Adsorption of ovalbumin on the latex surface was in excess of the quantity required to produce coverage of the surface over most of the protein concentrations range which was investigated. 2. "S" shaped isothermals which probably indicated multilayer adsorption were obtained. 3. The quantity of ovalbumin required to produce a constant surface charge density on the latex particle surface was a function of the pH, and a theory of active centers on the latex particles has been suggested. 4. A shift in the isoelectric point from that of native ovalbumin has been observed for the protein when adsorbed on a synthetic latex. (+info)
Ultrasonically induced in vitro cell lysis: node-antinode interactions.
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An attempt was made to discriminate between two hypotheses (standing wave, bubble recycling) of the mechanism of ultrasonically induced cell lysis in a rotating tube. A tube containing an aqueous suspension of P-388 cells was moved back and forth (+/- 3 or +/- 7 mm) during insonation (1 MHz, 5 W/cm2, continuous wave, 5 min). Cell lysis (approximately 20%) occurred. As a positive control, some tubes were also partially or completely rotated during insonation; considerable cell lysis (approximately 60%) occurred. The results are interpreted to suggest that both hypotheses are simultaneously useful in explaining the observed effect of cell lysis in a rotating tube. (+info)
Influence of waterproof covering on finger skin temperature and hand pain during immersion test for diagnosing hand-arm vibration syndrome.
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The purpose of this study was to examine the influence of waterproof covering on finger skin temperature (FST) and hand pain during immersion test for diagnosing hand-arm vibration syndrome complying with the proposal of the International Organization for Standardization (ISO/ CD14835-1, 2001) for measurement procedure. Six healthy male subjects took part in the immersion tests and immersed their both hands into water at 12 degrees C for 5 min, repeatedly with two types of waterproof covering (polyethylene and natural rubber gloves) or without hand covering (bare hands) during immersion. The FST data from middle fingers and subjective pain scores for hand pain were analyzed. Statistically significant differences in FST among three conditions were observed showing the highest FST with natural rubber gloves, followed by the FST with polyethylene gloves and the lowest with bare hands. Significant differences in pain score among three conditions were observed during immersion showing the lowest pain score with natural rubber gloves, followed by the pain score with polyethylene gloves and the highest with bare hands. Immersion test with polyethylene gloves instead of bare hands during immersion seems to be suitable for reducing subject suffering. (+info)
Comparative performance of playground surfacing materials including conditions of extreme non-compliance.
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OBJECTIVE: A recent case series study found that only 4.7% of 402 playgrounds in which arm fractures occurred in Victorian schools complied with the recommended 20 cm depth of tanbark. Tanbark depths at fall sites varied between 0-27 cm and the mean was 11.1 (5.0) cm. The purposes of the present study were to (1) measure impact attenuation properties of shallow and compacted depths of tanbark; (2) validate laboratory measurements with in situ data; (3) compare impact attenuation properties of compacted tanbark with an Australian manufactured rubber based surface material; and (4) study the impact performance of rubber and tanbark hybrid surfacing. METHODS: A standard test headform was dropped on tanbark and rubber surfaces in a laboratory setting to measure peak impact deceleration and head injury criterion (HIC) values. Variations in surface depth ranged from 2 cm-20 cm (tanbark) and 2 cm-9 cm (rubber). Drop height ranged from 0.5 m-2.5 m. RESULTS: Peak deceleration and HIC increased with increasing drop height and decreasing surface depth. Laboratory measurements at depths less than 8 cm overestimated peak deceleration and HIC values compared with in situ playground measurements. Impact attenuation of a 9 cm thick bilaminate rubber material was comparable to that of an 18 cm depth of compacted tanbark. Rubber-tanbark hybrid surfaces showed improved impact attenuation over individual surfaces. CONCLUSIONS: Compacted tanbark of depth less than 8 cm is ineffective in attenuating playground falls, resulting in excessive impact deceleration and HIC values. Shallow and compacted tanbark found in many Victorian school playgrounds poses a high risk for severe head injury. This calls for stricter enforcement of playground surface depth compliance. (+info)
Longitudinal study of sensitization to natural rubber latex among dental school students using powder-free gloves.
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BACKGROUND: A high rate of sensitization and clinical allergy to latex proteins has been reported in health care personnel. This is thought to be due to increased occupational exposure especially to natural rubber latex (NRL) gloves with an estimated prevalence varying widely (2.8-18%). OBJECTIVE: This was a longitudinal study to monitor a cohort of first-year dental students throughout 4 study years during exposure to powder-free gloves. Their atopic status was determined by skin prick testing using a panel of common allergens, and any sensitivity to latex proteins and the cross-reacting food allergens assessed. METHODS: Skin prick testing was carried out on the volunteers using latex, avocado, kiwi, banana, grass pollens, tree pollen, house dust mite and cat dander. Each volunteer completed a questionnaire detailing allergic history and any previous latex exposure. RESULTS: Skin prick testing showed a 65% incidence of atopy in the longitudinal study group. Initial latex skin testing was positive in 3 of the 63 students followed throughout their period of study. Subsequent testing gave a negative result in one student and one declined retesting. The third continued to give a positive response on each testing; she wore only nitrile gloves and remained free of clinical NRL allergy symptoms. No student developed latex sensitivity during the 5 yr of this study. CONCLUSION: Exposure to powder-free latex gloves was not associated with subsequent sensitization over 5 yr in a population with a high atopic incidence. (+info)
Bladder tumours in rubber workers: a factory study 1946-1995.
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BACKGROUND: Prior to December 1949, some British rubber industry workers were inadvertently exposed to the human bladder carcinogen beta-naphthylamine, which was present as a contaminant (at 0.25%) in antioxidants used in manufacturing. This study follows a composite cohort of 6450 men employed at a large tyre factory either during the 'at-risk' period or just after it. METHODS: A group of 2090 at-risk men (employed 1945-1949) and 3038 men, first employed only after January 1950, when the carcinogen had been removed, were followed for their bladder cancer morbidity and mortality experiences. RESULTS: Fifty-eight tumours were registered for those at risk, whereas only 33.9 were expected at national standardized registration rates [SRRN = 171 and 95% confidence interval (CI) = 130-221]. Thirty-nine bladder tumours were reported for the post-1950 intake, whereas 38.3 were expected (SRRN = 102 and 95% CI = 72-139). The use of mortality data did not reveal any underlying hazard because 12 of the 58 at-risk workers with tumours were still alive at the study end date. In only 16 instances was bladder cancer actually certified as the underlying cause of death. Plotting cases by their location of work on a factory plan assisted the interpretation. CONCLUSIONS: A statistically significant elevated risk of bladder cancer for the exposed workforce was evident, but this reversed when the carcinogen was removed from processing in October 1949. The use of morbidity (incidence) data in long-term studies of occupational bladder cancer should be the required methodology if the hazard and risk are not to be underestimated. (+info)
A study of mortality patterns at a tyre factory 1951-1985: a reference statistic dilemma.
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BACKGROUND: The general and cancer mortalities of rubber workers at a large tyre factory were studied in an area of marked regional variation in death rates. METHODS: Three quinquennial intakes of male rubber workers engaged between January 1946 and December 1960 formed a composite cohort of 6454 men to be followed up. Over 99% were successfully traced by December 1985. The cohort analysis used both national and local rates as reference statistics for several causes. RESULTS: Between 1951 and 1985, a national standardized mortality ratio (SMRN) of 101 for all causes (based on 2556 deaths) was noted, whereas the local standardized mortality ratio (SMRL) was only 79. For all cancers, the figures were 115 (SMRN) and 93 (SMRL), for stomach cancer they were 137 (SMRN) and 84 (SMRL), and for lung cancer they were 121 (SMRN) and 94 (SMRL). No outright excesses against the national norm were observed for other cancers except for larynx, brain and central nervous system and thyroid cancer and the leukaemias. Excesses were statistically significant for cancer of the gallbladder and the bile ducts, for silicotuberculosis (SMRN = 1000) and for the pneumoconioses (SMRN = 706). Deaths from cerebrovascular diseases, chronic bronchitis and emphysema showed statistically significant deficits using either norm. CONCLUSIONS: These results from a large factory cohort study of rubber workers, followed for over three decades, demonstrate the marked discrepancy that can result from using only one reference statistic in areas of significant variation in mortality patterns. (+info)
Analysis of phthalate contamination in infusion solutions by automated on-line in-tube solid-phase microextraction coupled with high-performance liquid chromatography.
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Contamination of infusion solutions with phthalates was analyzed, and its origin was determined. Phthalates were determined by on-line in-tube solid-phase microextraction coupled with high-performance liquid chromatography (in-tube SPME-HPLC) with UV detection. In-tube SPME is an extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. The infusion solutions were used without any pretreatment, and the phthalates in these solutions were automatically analyzed by the on-line in-tube SPME-HPLC system. The limits of detection of phthalates in the infusion solutions were 1-10 ng/mL. With a few exceptions, the recoveries of phthalates added to the infusion solutions were above 80%. Di-n-butyl phthalate (DBP) was detected at a concentration of 7-60 ng/mL in most infusion solutions in plastic containers but was not detected in those in glass bottles. On the other hand, no other phthalates were detected in infusion solutions in either plastic or glass containers. Large amounts of DBP were detected in the adhesive used to affix the paper labels to the plastic bottles and bags, but not in the plastic containers themselves. Furthermore, DBP was shown to be readily eluted from the adhesive into water and alcohol and easily pass through the plastic. These results indicated that the source of the DBP was the adhesive used to affix the paper labels, and DBP contaminated the infusion solutions by passing through the plastic. The in-tube SPME-HPLC method is simple and rapid and provides a useful tool for the screening and determination of phthalate contamination in infusion solutions. (+info)