Carbonate chemistry of an in-situ free-ocean CO2 enrichment experiment (antFOCE) in comparison to short term variation in Antarctic coastal waters.

Free-ocean CO2 enrichment (FOCE) experiments have been deployed in marine ecosystems to manipulate carbonate system conditions to those predicted in future oceans. We investigated whether the pH/carbonate chemistry of extremely cold polar waters can be manipulated in an ecologically relevant way, to represent conditions under future atmospheric CO2 levels, in an in-situ FOCE experiment in Antarctica. We examined spatial and temporal variation in local ambient carbonate chemistry at hourly intervals at two sites between December and February and compared these with experimental conditions. We successfully maintained a mean pH offset in acidified benthic chambers of -0.38 (±0.07) from ambient for approximately 8 weeks. Local diel and seasonal fluctuations in ambient pH were duplicated in the FOCE system. Large temporal variability in acidified chambers resulted from system stoppages. The mean pH, Ωarag and fCO2 values in the acidified chambers were 7.688 ± 0.079, 0.62 ± 0.13 and 912 ± 150 µatm, respectively. Variation in ambient pH appeared to be mainly driven by salinity and biological production and ranged from 8.019 to 8.192 with significant spatio-temporal variation. This experiment demonstrates the utility of FOCE systems to create conditions expected in future oceans that represent ecologically relevant variation, even under polar conditions.

Percutaneous absorption of Octopirox.

[14C]Octopirox administered to rats by intubation or injection was excreted mostly in the faeces (65-85% of the dose) with smaller amounts (6-19%) in the urine. Blood levels after intubation of Octopirox (4.8 mg/kg body weight) reached a maximum equivalent to 0.137 micrograms/ml at 2 hr and declined to 0.007 micrograms/ml at 48 hr after administration. Tissue levels were low, the greatest was the liver with the equivalent of 3 micrograms Octopirox at 6 hr after intubation. With female rats skin penetration of Octopirox at 1% (v/v) in shampoo without rinsing was 65.1 micrograms/cm2 under non-occlusive conditions for 48 hr. When the skin was rinsed after a 10-min contact, penetration was reduced to 3.4 micrograms/cm2 under occlusive, and 2.0 micrograms/cm2 under non-occlusive conditions. Skin penetration of Octopirox was dependent on duration of contact up to 10 min before rinsing. Penetration at 1% Octopirox increased significantly from 2.4 micrograms/cm2 after 2.5 min exposure to 4.5 micrograms/cm2 after 10 min contact, but there was no further increase in penetration with a 20-min application. Skin penetration and deposition of Octopirox were both proportional to Octopirox concentration between 0.1 and 1% (w/v); skin penetration increased from 0.31 to 3.6 micrograms/cm2 while deposition increased from 0.8 to 7.6 micrograms/cm2. There was no significant difference between the penetration through clipped skin and hairy skin from an application of 1% Octopirox for 5 min followed by rinsing. Under non-occlusive conditions, penetration was 1.5 micrograms/cm2 for both types of skin. Blood levels after topical application (15.4 mg/kg body weight) without rinsing and with occlusion reached the equivalent of 0.32 micrograms/ml at 6 hr. However, when the skin was rinsed and protected with a non-occlusive patch blood levels were reduced to a maximum equivalent to 0.02 micrograms/ml at 1 hr after application. The safety factor estimated for the consumer using a shampoo containing 1% Octopirox is 29,400, so that the possibility of systemic effects due to absorption through the skin is remote.

Safety and immunogenicity of a vaccine bait containing ERA strain of attenuated rabies virus.

Ninety percent of foxes fed commercial ERA vaccine in a specially designed bait developed rabies serum neutralizing antibodies. The vaccine bait did not cause clinical signs of rabies when consumed by foxes, raccoons, skunks, dogs, cats, cattle and monkeys. When presented, in the laboratory, to wild rodents of the species Microtus, Mus musculus and Peromyscus, the vaccine baits caused vaccine-induced rabies only in Mus musculus. Laboratory mice of the CD-1 and CLL strain were susceptible to vaccine-induced rabies; however, studies showed that transmission of virus to other animals did not occur. These studies suggest that the vaccine bait described could be useful in a rabies control program in areas where foxes and wild dogs are the principal vectors.

Metabolism in the rat of potassium nonan-5-sulphate, a symmetrical anionic surfactant.

1. The metabolism of potassium nonan-5-[35S]sulphate, a symmetrical secondary alkylsulphate ester, was investigated in the rat. Oral administration of the radiolabelled ester was followed by the elimination of the majority of radioactivity in the urine. 2. Potassium nonan-5-[35S]sulphate is degraded in vivo to produce at least three radiolabelled sulphate esters. 3. The same metabolites were produced by isolated rat livers perfused with potassium nonan-5-[35S]sulphate. 4. The three radioactive metabolites were identified by combined g.l.c.-mass spectroscopy as the unchanged parent ester, nonan-1-ol-5-sulphate and nonanoate-5-sulphate. 5. The nature of the latter two metabolites indicates that potassium nonan-5-sulphate is metabolized by omega-oxidation only and, moreover, the alkylsulphate ester is metabolized only at one end of the molecule.

The mode of action of ethyl lactate as a treatment for acne.

We have shown that an alcoholic lotion containing ethyl lactate when applied topically to rat skin under occlusion became localized in the follicles and sebaceous glands. When applied to human facial skin the ethyl lactate was hydrolysed to ethanol and lactic acid, and thereby lowered the skin pH. Under such conditions the growth of recoverable skin bacteria, in particular the anaerobe Propionibacterium acnes, was inhibited, and the hydrolysis of sebum to free fatty acids by lipase derived from the bacteria was greatly impaired. These effects of ethyl lactate would account for its observed clinical efficacy in acne vulgaris.

Effect of 2-hydroxyacids on guinea-pig footpad stratum corneum: mechanical properties and binding studies.

Synopsis The effect of aqueous solutions of 2-hydroxyacids of chain length C(3) to C(10) on the extensibility of undamaged and solvent-damaged guinea-pig footpad stratum corneum has been studied. The increase in extensibility of solvent-damaged corneum, caused by treatment with hydroxyacid, reached a maximum with 2-hydroxycaprylic acid (C(8)); on undamaged corneum, 2-hydroxycaprylic acid was the only hydroxyacid studied to give a significant effect. The increase in corneum extensibility produced by 2-hydroxyacids decreases when the pH is raised from 3 to 4. This loss of effect correlates with the ionization of the hydroxyacid (pK 3.85). The binding of radiolabelled 2-hydroxycaproic (C(6)) and 2-hydroxycaprylic acids to stratum corneum has been studied. 2-Hydroxycaprylic acid binds much more strongly than 2-hydroxycaproic acid, the difference in the binding being consistent with the hydrophobic binding energy of two methylene groups. Raising the pH above 3.5 results in a large decrease in the binding of 2-hydroxycaprylic acid in line with the corresponding reduction in extensibility. Treatment with 2-hydroxyacids results in a small increase in the water-binding capacity of solvent-damaged stratum corneum, but in a decrease in the water-binding capacity of undamaged stratum corneum. These data are discussed in terms of a possible mechanism for the plasticizing of stratum corneum.

Percutaneous absorption of 2-nitro-p-phenylenediamine.

Synopsis Studies have been done on the absorption and metabolism of the hair colourant 2-nitro-p-phenylenediamine (2-NPPD) in rats with particular reference to skin penetration. When [(14)C]2-NPPD was given orally or injected intraperitoneally into male and female rats, excretion was rapid and mainly in the faeces (60%) and urine (35%). No radioactivity was measurable in the expired air. At 3 days after dosing, approximately 2% of the dose was retained in the body. Application of [(14)C]2-NPPD in ethanol to the clipped skin of rats gave a high skin penetration. Male rats absorbed less (11.7 mug cm(-2)) through the skin than did female rats (24.6 mug cm(-2)). Application of [(14)C]2-NPPD in a solution of a hair colourant product base to the clipped skin of rats gave a high penetration if the skin was occluded or not rinsed. Penetration was much reduced after rinsing and protection by non-occlusive patches. With these latter conditions, skin penetration in clipped rats treated with a 0.5% (w/v) solution of [(14)C]2-NPPD doubled to 6.1 mug cm(-2) when the contact time was increased from 5 to 30 minutes, increased two to three times after two and three repeated applications, increased in proportion to the applied concentration and was reduced by half when applied to unclipped skin. The metabolic pattern in urine from rats after different routes of administration showed only a trace of the parent [(14)C]2-NPPD but six other radioactive components. The identity of these components has not yet been fully resolved. Blood levels of radio-activity during 2 days after topical administration were low. Under realistic conditions of use by the consumer the calculated dose through the skin based on the experimental rat data is up to 10 mug/kg body weight per application of a semi-permanent hair colourant product containing 1% of 2-NPPD.

Immunization of foxes Vulpes vulpes by the oral and intramuscular routes with inactivated rabies vaccines.

Inactivated rabies vaccines prepared from common vaccine strains of virus were inoculated into foxes by the intramuscular and intestinal route. There were differences among the vaccines in the duration of antibody produced after intramuscular administration. Inactivated vaccines deposited directly into the lumen of the duodenum by means of a fiberscope caused seroconversion in some foxes, especially following a booster dose, but the antibodies produced were for the most part of short duration. The ERA modified live virus vaccine, in contrast, produced a satisfactory and long lasting antibody after intestinal instillation.

The effect of configuration of the sulphate moiety on the metabolism of potassium octan-2-sulphate in the rat.

1. A comparison was made of the metabolism of potassium D-(+)-octan 2-[35S]sulphate and potassium L-(-)-octan-2-[35S]sulphate in the rat. 2. Following administration of either enantiomer orally or i.v. the major proportion of the radioactivity was excreted in the urine within 24 h. When either enantiomer was administered i.v. to rats with bile-duct and ureter cannulae, the majority of the radioactivity was eliminated in the urine within six hours with only small amounts in bile. 3. Both enantiomers were extensively degraded in vivo. The metabolic products were identical with those previously reported (Maggs et al. 1982). 4. The major difference in the metabolite patterns was with respect to the relative amounts of hexanoate-5-sulphate: male and female urines contained approx. twice as much of this metabolite when the D-(+)-isomer was administered. In addition, isomer and sex-linked differences were observed with respect to the amounts of octanoate-7-sulphate.

Metabolism in the rat of potassium DL-octan-2-sulphate, a secondary alkyl sulphate.

1. The metabolism of potassium [2-14C]octan-2-sulphate and potassium octan-2-[35S]sulphate was investigated in the rat. Following oral administration, the bulk of the radioactivity was eliminated in the urine within 24 h. 2. Whole-body radioautography showed the liver to be the principal site of tissue accumulation of radiolabel following administration of 14C- or 35S-labelled DL-octan-2-sulphate. 3. Octan-2-sulphate was extensively degraded in vivo. The major urinary components are five sulphate estes, present in urine in essentially the same proportions regardless of label. The relative proportions of radioactivity associated with the urinary components showed considerable differences between male and female rats. 4. Three of the components have been identified as butanoate-3-sulphate, hexanoate-5-sulphate and octanoate-7-sulphate. The remaining metabolite was tentatively identified as an aldehyde derivative of octan-2-sulphate, a possible intermediate in the formation of octanoate-7-sulphate.

The safety and efficacy of immunizing foxes (Vulpes vulpes) using bait containing attenuated rabies virus vaccine.

Foxes given ERA rabies vaccine baits were challenged at one, six, 12 and 24 months later and showed a resistance to challenge in 80%, 78%, 60% and 44% of individuals respectively. All animals showing seroconversion following vaccination, resisted challenge at 24 months, suggesting that successful vaccination by the oral route could confer a relatively long term duration of immunity. The trials showed that fox pups did not immunize as easily as adult foxes using ERA rabies vaccine baits. Back-passage studies and the consumption of ERA injected mice by foxes failed to show any reversion of the vaccine virus to a virulent state. The fox and mouse are shown to be highly susceptible to rabies street virus, while the domestic species tested are consisderably more resistant. Monkeys were found to be intermediate in susceptibility to the virus. Safety tests carried out on various species of wildlife showed only the mouse to be susceptible to infection from ingesting the vaccine in the form of a bait. ERA rabies vaccine was shown to be safe in monkeys even when high titred virus was administered by the oral route.

Metabolism of the surfactants sodium undecyltriethoxy sulphate and sodium dodecyltriethoxy sulphate in the rat.

The metabolic fates of the synthetic surfactants, sodium [1-(14)C]undecyltriethoxy sulphate and sodium [1-(14)C]dodecyltriethoxy sulphate were studied in the rat. Both compounds were extensively metabolized regardless of the route of administration, oral, intraperitoneal or intravenous. Short-chain radioactive products were eliminated in the urine: the major metabolite of the dodecyl homologue in the urine was identified as (-)O(2)C(14)CH(2)- (OC(2)H(4))(3)OSO(3) (-) by n.m.r. and g.l.c.-mass spectrometry, whereas the major metabolite of the undecyl homologue in the urine was tentatively identified as (-)O(2)CCH(2) (14)CH(2)- (OC(2)H(4))(3)OSO(3) (-). In contrast with experiments with the dodecyl derivative, when [1-(14)C]undecyltriethoxy sulphate was administered to rats, appreciable amounts of radioactivity were recovered as (14)CO(2) in expired air. Whole-body radioautography implicated the liver as the major site of metabolism of both surfactants. The nature of the metabolic products establishes that both compounds are degraded by omega,beta-oxidation. Cleavage of the ether linkage proximal to the sulphate moiety may account for the small amounts of (14)CO(2) recovered in expired air after the administration of [1-(14)C]dodecyltriethoxy sulphate. It is suggested the substantial amounts of (14)CO(2) recovered after [1-(14)C]-undecyltriethoxy sulphate administration originate from (-)O(2) (14)C(OC(2)H(4))(3) OSO(3) (-), an unstable product of omega,beta-oxidation. An n.m.r. spectrum of the metabolite identified as 2-(triethoxy sulphate)acetic acid and a mass spectrum of the trimethylsilyl derivative of the parent alcohol of that metabolite have been deposited as Supplementary Publication SUP50086 (5 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.

Percutaneous absorption and disposition of Tinopal EMS.

A cotton-substantive, anionic, fluorescent whitening agent manufactured by several suppliers under various trade names e.g. Tinopal EMS, has been synthesized in radioactive form. Intubation of detergent or aqueous solution into rats resulted in little absorption from the intestinal tract as evidenced by low radioactivity in the urine and tissues. Most of the dose was excreted rapidly in the faeces. After parenteral administration to rats, the radioactivity was rapidly excreted in the faeces with small amounts remaining in tissues and organs. There was slight evidence of retention of radioactivity in the kidneys. Very small amounts of Tinopal EMS in detergent were absorbed through rat skin, but only when concentrations greater than those normally used by the consumer, together with occlusion of the skin were employed. Small amounts were absorbed throught skin when applied in ethanol. It is concluded that the possibility of systemic toxic effects in man as a result of percutaneous absorption is remote.

Percutaneous absorption of triclocarban in rat and man.

The route and rate of excretion by rats of the germicide (1 4 C) Triclocarban formerly called trichlorocarbanilide, given by parenteral injection has been investigated. Blood levels based on radioactivity and by chemical determination after parenteral injection have been compared with those obtained after topical application of (1 4 C) Triclocarban in soaps and in dimethylformamide (DMF) through occluded rat skin has been studied. Other soaps and a hand cleanser containing (1 4 C) Triclocarban have been applied to rat skin without occlusion and the effects of duration of contact, concentration and the use of a solubilizer have been investigated. In humans, absorption of Triclocarban through skin after bathing daily for 28 days has been investigated by chemical analysis of blood and urine. The data show that elimination by the rat is rapid and complete principally via the faeces. Blood levels after parenteral injection are low and comparison of the radioactivity and chemical determinations suggest rapid metabolism of the Triclocarban. After application to the skin, blood levels based on 1 4 C are very low. Absorption of (1 4 C) Triclocarban through occluded rat skin was greater from DMF than from soaps. With non-occluded rat skin, absorption from soaps was less and was dependent on concentration but independent of duration of contact. The use of a solubilizer did not increase absorption through skin. No measurable Triclocarban (less than 25 ppb) was present in blood and urine samples of volunteers during or shortly after a 28-day intensive bathing regimen.

The repair of impaired epidermal barrier function in rats by the cutaneous application of linoleic acid.

Epidermal barrier function in rats was experimentally impaired by two separate means, namely, by rendering the animals deficient in essential fatty acids and by evoking a primary cutaneous irritant response by treating with a solution of sodium laurate. Impaired barrier function was manifested by a greatly increased rate of transepidermal water loss. Application to the skin of sunflower seed oil, which is rich in linoleic acid, rapidly restored to normal the abnormally high rates of transepidermal water loss in both experimental cases, and it was shown with the essential fatty acid-deficient rats that there was a concomitant incorporation of linoleic acid of the sunflower seed oil into epidermal lipids. Cutaneous application of olive oil, which is low in linoleic acid but rich in the non-essential oleic acid, did not influence epidermal barrier function. A close relationship of barrier function and essential fatty acids is indicated.

Comparative percutaneous absorption of pyrithiones.

The percutaneous absorption of 3H or 35S labelled pyridine-2-thione-N-oxide (PT) through the skin of rat, rabbit and guinea pigs in vivo is reported. The sodium (Na) zinc (Zn) and zirconium (Zr) derivatives of PT were studied and the effects of duration of contact and concentration of the NaPT and ZnPT in test solutions were examined. Shampoo test solutions containing the isotopically labelled PT were applied to the skin of the animals. The skins were then rinsed, the treated areas of skin protected and excreta were monitored for the isotope for 2 days after treatment. Penetration was calculated from the amounts of isotope in the excreta. Further groups of animals were treated with test solutions applied under occlusive patches for 6 h before rinsing the skin. The turnover of Na and ZnPT in the three species after intraperitoneal and subcutaneous injection was measured. All three species rapidly excreted the injected isotope principally via the urine. The comparative penetration of the three PT samples was Na greater than Zr greater than Zn from all treatments. The comparative permeability of the animals' skins to these PTs was rabbit greater than rat greater than guinea pig. NaPT penetration was found to be dependent upon duration of contact and concentration in the test solution whereas the penetration of ZnPT was found to be proportional to concentration but independent of duration of contact of the test solution. Extrapolation of these findings to the use of shampoos containing up to 1% (w/v) ZnPT by man indicated an adequate margin of safety for use of this type of product.