A highly efficacious pediculicide based on dimeticone: Randomized observer blinded comparative trial

BACKGROUND: Infestation with the human head louse (Pediculus humanus capitis) occurs worldwide. Existing treatment options are limited, and reports of resistance to commonly used pediculicides have been increasing. In this trial we assessed the efficacy of a product containing a high (92%) concentration of the silicone oil dimeticone (identical in composition to NYDA(R)), as compared to a 1% permethrin lotion. METHODS: Randomized, controlled, observer blinded clinical trial. Participants were recruited from a poor urban neighbourhood in Brazil where pediculosis capitis was highly prevalent. To minimize reinfestation during the trial, participants (145 children aged 5-15 years with head lice infestations) were transferred to a holiday resort outside the endemic area for a period of 9 days. Two applications of dimeticone or 1% permethrin were done, seven days apart. Outcome measures were defined as cure (absence of vital head lice) after first application and before and after second applications, degree of itching, cosmetic acceptability, and clinical pathology. RESULTS: Overall cure rates were: day 2 - dimeticone 94.5% (95% CI: 86.6% - 98.5%) and permethrin 66.7% (95% CI: 54.6% - 77.3%; p < 0.0001); day 7 - dimeticone 64.4% (95% CI: 53.3% - 75.3%) and permethrin 59.7% (95% CI: 47.5% - 71.1%; p = 0.5); day 9 - dimeticone 97.2% (95% CI: 90.3% - 99.7%) and permethrin 67.6% (95% CI: 55.4%-78.2%); p < 0.0001). Itching was reduced similarly in both groups. Cosmetic acceptability was significantly better in the dimeticone group as compared to the permethrin group (p = 0.01). Two mild product-related incidents occurred in the dimeticone group. CONCLUSION: The dimeticone product is a safe and highly efficacious pediculicide. Due to its physical mode of action (interruption of the lice's oxygen supply of the central nervous system), development of resistance is unlikely. TRIAL REGISTRATION: Current Controlled Trials ISRCTN15117709

Pollutant effects on genotoxic parameters and tumor-associated protein levels in adults: a cross sectional study

<p>Abstract</p> <p>Background</p> <p>This study intended to investigate whether residence in areas polluted by heavy industry, waste incineration, a high density of traffic and housing or intensive use of pesticides, could contribute to the high incidence of cancer observed in Flanders.</p> <p>Methods</p> <p>Subjects were 1583 residents aged 50–65 from 9 areas with different types of pollution. Cadmium, lead, p,p'-DDE, hexachlorobenzene, PCBs and dioxin-like activity (Calux test) were measured in blood, and cadmium, t,t'-muconic acid and 1-hydroxypyrene in urine. Effect biomarkers were prostate specific antigen, carcinoembryonic antigen and p53 protein serum levels, number of micronuclei per 1000 binucleated peripheral blood cells, DNA damage (comet assay) in peripheral blood cells and 8-hydroxy-deoxyguanosine in urine. Confounding factors were taken into account.</p> <p>Results</p> <p>Overall significant differences between areas were found for carcinoembryonic antigen, micronuclei, 8-hydroxy-deoxyguanosine and DNA damage. Compared to a rural area with mainly fruit production, effect biomarkers were often significantly elevated around waste incinerators, in the cities of Antwerp and Ghent, in industrial areas and also in other rural areas. Within an industrial area DNA strand break levels were almost three times higher close to industrial installations than 5 kilometres upwind of the main industrial installations (p < 0.0001). Positive exposure-effect relationships were found for carcinoembryonic antigen (urinary cadmium, t,t'-muconic acid, 1-hydroxypyrene and blood lead), micronuclei (PCB118), DNA damage (PCB118) and 8-hydroxy-deoxyguanosine (t,t'-muconic acid, 1-hydroxypyrene). Also, we found significant associations between values of PSA above the p90 and higher values of urinary cadmium, between values of p53 above the p90 and higher serum levels of p,p'-DDE, hexachlorobenzene and marker PCBs (PCB 138, 153 and 180) and between serum levels of p,p'-DDE above the p90 and higher serum values of carcinoembryonic antigen. Significant associations were also found between effect biomarkers and occupational or lifestyle parameters.</p> <p>Conclusion</p> <p>Levels of internal exposure, and residence near waste incinerators, in cities, or close to important industries, but not in areas with intensive use of pesticides, showed positive correlations with biomarkers associated with carcinogenesis and thus probably contribute to risk of cancer. In some rural areas, the levels of these biomarkers were not lower than in the rest of Flanders.</p

The Nevados de Payachata volcanic region (18°S/69°W, N. Chile)

Subduction-related volcanism in the Nevados de Payachata region of the Central Andes at 18°S comprises two temporally and geochemically distinct phases. An older period of magmatism is represented by glaciated stratocones and ignimbrite sheets of late Miocene age. The Pleistocene to Recent phase (≤0.3 Ma) includes the twin stratovolcanoes Volcan Pomerape and Volcan Parinacota (the Nevados de Payachata volcanic group) and two small centers to the west (i. e., Caquena and Vilacollo). Both stratovolcanoes consist of an older dome-and-flow series capped by an andesitic cone. The younger cone, i. e., V. Parinacota, suffered a postglacial cone collapse producing a widespread debris-avalanche deposit. Subsequently, the cone reformed during a brief, second volcanic episode. A number of small, relatively mafic, satellitic cinder cones and associated flows were produced during the most recent activity at V. Parinacota. At the older cone, i. e., V. Pomerape, an early dome sequence with an overlying isolated mafic spatter cone and the cone-forming andesitic-dacitic phase (mostly flows) have been recognized. The two Nevados de Payachata stratovolcanoes display continuous major- and trace-element trends from high-K 2 O basaltic andesites through rhyolites (53%–76% SiO 2 ) that are well defined and distinct from those of the older volcanic centers. Petrography, chemical composition, and eruptive styles at V. Parinacota differ between pre- and post-debris-avalanche lavas. Precollapse flows have abundant amphibole (at SiO 2 > 59 wt%) and lower Mg numbers than postcollapse lavas, which are generally less silicic and more restricted in composition. Compositional variations indicate that the magmas of the Nevados de Payachata volcanic group evolved through a combination of fractional crystallization, crustal assimilation, and intratrend magma mixing. Isotope compositions exhibit only minor variations. Pb-isotope ratios are relatively low ( 206 Pb/ 204 Pb = 17.95–18.20 and 208 Pb/ 204 Pb = 38.2–38.5); 87 Sr/ 86 Sr ratios range 0.70612–0.70707, 143 Nd/ 144 Nd ratios range 0.51238–0.51230, and γ 18 O SMOW values range from + 6.8% o to + 7.6% o SMOW. A comparison with other Central Volcanic Zone centers shows that the Nevados de Payachata magmas are unusually rich in Ba (up to 1800 ppm) and Sr (up to 1700 ppm) and thus represent an unusual chemical signature in the Andean arc. These chemical and isotope variations suggest a complex petrogenetic evolution involving at least three distinct components. Primary mantle-derived melts, which are similar to those generated by subduction processes throughout the Andean arc, are modified by deep crustal interactions to produce magmas that are parental to those erupted at the surface. These magmas subsequently evolve at shallower levels through assimilation-crystallization processes involving upper crust and intratrend magma mixing which in both cases were restricted to end members of low isotopic contrast.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47805/1/445_2005_Article_BF01073587.pd