Dexamethasone serum concentrations after intravenous administration in horses during race training

Dexamethasone (DXM) sodium phosphate is a widely used corticosteroid for inflammatory conditions in horses, regulated in racing jurisdictions in the USA by a 0.005 ng/ml serum/plasma threshold. This study seeks to describe serum concentrations of DXM at 48 and 72 h after intravenous administration of 20 mg DXM sodium phosphate over 1 to 5 days, and to identify a possible source of DXM overages. 74 horses (39 Thoroughbreds, 13 Standardbreds, 22 Quarter Horses) in active race training received 20 mg DXM sodium phosphate. Serum was collected before injection, at 48 and 72 h post last injection, and analysed by LC/MS-MS (limit of quantification (LOQ) = 2.5 pg/ml). No differences were identified by ANOVA (P≤0.05) for racing breeds, age, gender or the number of days of DXM sodium phosphate administration, so data were pooled for each time point. The DXM serum concentration at 48 h (mean ± standard deviation, range) was 2.18±1.56 pg/ml (<2.5 to 40 pg/ml). Summary statistics could not be derived for 72 h DXM serum concentration data owing to censored data, but ranged from <2.5 to 95.8 pg/ml. There was one extreme outlier (Tukey) at 48 h, and two extreme outliers at 72 h. A separate study was conducted using sedentary experimental horses to determine the likelihood that positive DXM samples could result from environmental transfer. Urine was collected from a mare 2 to 3 h post administration of 20 mg DXM. Hay with 100 ml of the DXM (17 ng/ml) containing urine was offered to each of six experimental horses and blood was collected at 0, 4, 8, 12, 16, 20 and 24 h. All six horses had plasma DXM concentration above the limit of detection and five of six had plasma DXM concentrations above the LOQ for at least one sample time.

An interim screening limit of detection for naproxen in equine plasma: a review and analysis

Starting in August 2015 Thoroughbred racing in Charles Town, West Virginia experienced a sequence of intermittent low concentration Naproxen identifications from 6.3 to 161 ng/ml of plasma (27.3 to 699 nM). These identifications were ongoing, indicating the horsemen were unaware of their origins. Naproxen is administered orally to horses at substantial doses and is chemically stable in the environment. These identifications are therefore most likely associated with exposure of these horses to environmental traces of Naproxen. Given the low concentrations of these identifications, we were asked to identify a Screening Limit of Detection (SLOD) below which these trace level Naproxen identifications would not be reported. Review of the data set suggested an SLOD of 200 ng/ml, while outlier analysis suggested an ‘extreme’ outlier level at 247 ng/ml, which figure was rounded up to 250 ng/ml Naproxen or 1.09 uM. This proposed SLOD is in good agreement with other US regulatory thresholds for therapeutic medications and this Interim Screening Limit of Detection was presented for review.

A multidisciplinary approach to head and neck cancer

Head and neck cancer and its treatment can leave patients with impaired swallowing and ability to communicate. A multidisciplinary approach from the speech and language therapist and dietician can help the patient maximise their function and identify when additional methods of support are required.

An electrical model for Periplaneta americana pronotal integument: an epidermal location for hydration-dependent resistance

Measurements of electrical resistance appear to be useful indicators of porosity and related water permeability in insect cuticle. To develop an adequate understanding of how such measurements relate to the physical and structural properties of the integument, we made detailed determinations of resistance and impedance values for pronotal cuticle in adult male Periplaneta americana. The most consistent estimates were obtained by averaging measurements across the integument on both sides of the midline at several intervals starting 15 min after electrode application. Pronotal resistance varied inversely with water content, from about 10 k omega cm2 in hydrated cockroaches to about 40 k omega cm2 in dehydrated insects. Though the dermal gland canals appear to act as the main conductive pathway across the cuticle, the variable 'barrier' is located in the epidermal layer, since removal of the epidermis from isolated pronota also removes most of the variable component of the integumental resistance. Comparison of measurements between two external electrodes with single-electrode measurements revealed a 'shunt' pathway parallel to the cuticle surface; modelling this shunt suggested that it was variable and located mostly internal to the cuticle, supporting an epidermal location for a variable barrier. Impedance measurements over a range of frequencies showed the integument to be electrically complex, and a model is proposed to account for its properties.

EVIDENCE FOR HYDRATION-DEPENDENT CLOSING OF PORE STRUCTURES IN THE CUTICLE OF PERIPLANETA AMERICANA

Integumental electrical resistances were measured on the antenna, pronotum, forewing, second abdominal tergite, fifth abdominal sternite and the femur of the third leg in restrained male and female Periplaneta americana. The same measurements, excepting those on antenna and wing, were made on last-instar nymphs. Electrical contact was made through two externally applied glass tubes filled with cockroach Ringer with a combined contact area of about 2 mm2. Resistances corresponding to current flows through two thicknesses of integument were measured using a current-clamping amplifier. Calculated electrical conductances tended to be higher in the antennae, pronotum and abdominal tergites than in the legs and wings. Conductances of the pronotum and abdominal tergites were significantly higher (P&lt;0.001) in males than in females. The literature suggests that male abdominal tergites are the site of sex pheromone production. In nymphs as well as adults, the conductances of all areas, except the antennae of males, decreased following dehydration and a decline in animal water content. In most cases the magnitude of the decrease was tightly correlated with initial hydrated conductance. The data suggest that variations in regional conductances in hydrated animals are principally due to differences in dermal gland density. We argue that the decrease in conductance following dehydration is evidence of a mechanism closing dermal gland openings in times of water stress.

Atmospheric Water Absorption and the Water Budget of Terrestrial Isopods (Crustacea, Isopoda, Oniscidea)

Studies of terrestrial isopods (Crustacea, Isopoda, Oniscidea) have revealed a capacity for active water vapor absorption (WVA) in the taxonomic sections Crinocheta and Diplocheta but not in Synocheta. Uptake thresholds in Crinocheta are modest by comparison with other vapor absorbers, but standardized uptake fluxes are among the highest recorded and are probably an adaptive requirement to counter the high transpiratory losses. Comparative data for uptake fluxes, thresholds, and transpiratory losses allows the compilation of water budgets in hypothetical temperature and humidity regimes. Given a 12-h light-dark cycle, with saturated ambient activities for diurnal WVA, all species could recover water losses incurred during nocturnal foraging in an ambient water activity of 0.75, and xeric species could forage in activities below 0.30. Xeric trends based on these models agree closely with predictions from ecotypic surveys. In the littoral Ligia oceanica (Diplocheta) haemolymph hyperosmosis and periodic submergence provide additional means of water balance regulation. It is proposed that WVA in Ligia provides an essentially solute-free water source to counteract salt-loading in the splash-zone. The absence of WVA in synochetes, together with their cryptozoic habits, reflects an alternative terrestrial strategy to those of other oniscideans.

Population-based epidemiology of human immunodeficiency virus infection in Western Australia. Western Australian AIDS Advisory Committee

A total of 328 cases of infection with human immunodeficiency virus (HIV) in Western Australia in 1983-1987 was studied with respect to demographic factors, the risk profile, the clinical progression of disease, the utilization of inpatient services and trends in incidence over time. The crude incidence rates were 8.8 cases/100,000 person-years in men and 0.4 cases/100,000 person-years in women. Age-specific rates peaked at 25 to 29 years of age in men. The risk of HIV infection was associated with metropolitan residence, low socioeconomic level, and two specific occupational groups. Homosexual and bisexual men constituted 86% of all cases; the incidence rate of HIV infection in such men was approximately 1000-times higher than was the incidence rate by apparent sexual transmission in heterosexual persons. However, the proportion of cases that occurred in women or that apparently was caused by heterosexual sexual transmission increased from zero in 1983-1984 to 7.5% and 5.4%, respectively, in 1987. After two years of follow-up, 71% of preclinical (category-C) patients had developed signs, symptoms or evidence of immune dysfunction, and 12% of those patients with lymphadenopathy or with other early clinical features of disease (category-B) had progressed to the acquired immunodeficiency syndrome (AIDS). At 21 months of follow-up, the survival rate with AIDS was 9%. Patients with AIDS utilized an average of 68.9 short-stay hospital bed-days per person-year, while category-B patients used 11.5 hospital bed-days per person-year. Notifications of HIV infection increased each year from 1983 to 1986, but fell by 22% in 1987. The latter may have been as a result of chance, a screening artefact or a real reduction in the incidence rate.

Time trends in prevalence of cervical cytological abnormality in women attending a sexually transmitted diseases clinic and their relationship to trends in sexual activity and specific infections

Trends in prevalence of cytological evidence of cervical intraepithelial neoplasia (CIN) and cervical infection with human papilloma virus (HPV), as indicated by HPV infection and dyskeratosis, were studied in 2,992 new attenders at a sexually transmitted diseases (STD) clinic between 1978 and 1982. Crude prevalence of CIN increased from 1.3% to 4.3% (P less than 0.001) and crude prevalence of HPV infection increased from 2.8% to 9.3% (P less than 0.001). Age adjustment had little effect on these trends. Review, in 1984-85, of samples of smears taken in 1978 and 1982 showed that recognition of koilocytosis by the laboratory had increased substantially over time while a tendency had developed to downgrade nuclear changes in the presence of koilocytosis. Correction of the 1978 and 1982 smear results to the 1984-85 classifications suggested that prevalence of koilocytosis had increased little (from 13.4% to 16.1%, P = 0.20) while there had been a substantial real increase in CIN (0.8% to 2.4%, P less than 0.001). To try to explain the trend in CIN, other characteristics of a sample of attenders at the STD clinic were studied. There were no appreciable trends in prevalence of past STD, number of sexual partners in the last 3 months, method of contraception, genital warts and culture of N. gonorrhoea, T. vaginalis, C. albicans and Chlamydia sp. from the vagina. There was an increase in the proportions in socioeconomic group I, as classified by postcode of residence (17.0% to 26.9%, P = 0.04), referred as contacts rather than with symptoms (24.0% to 41.6%, P less than 0.001), with a clinical diagnosis of genital herpes (5.0% to 8.6%, P = 0.08) and with herpes virus cultured from the cervix (2.1% to 6.3%, P = 0.03). The trend in prevalence of herpes virus infection was not explained by the other trends. It may explain the trend in prevalence of CIN.

Transport characteristics of the isolated rectal complex of the mealworm Tenebrio molitor

The coupling between water and ion transport in the rectal complex of mealworms can be studied further using an in vitro preparation under oil. Preliminary investigations into the properties of such a preparation are described. The preparation remains viable over several hours when sustained with transportable cations, primarily potassium but not sodium, which appears to be the limiting factor in generating long-term water absorption. Potassium is selectively transported by the Malpighian tubules surrounding the rectum, thus generating osmotic forces necessary for water absorption from within the lumen. Reabsorption was studied using sucrose solutions of different concentrations in the rectal lumen. The preparation absorbed water from extremely low water activities down to the same threshold value (aw = 0.88) observed in intact animals. Absorption rates were less than half those observed in vivo, probably because of the viscosity of the sucrose solutions. Transported water emerging from the common duct of the preparation included a significant contribution from the haemolymph.

Allometry of water vapor absorption in two species of tenebrionid beetle larvae

Water vapor absorption is compared in the two tenebrionid larvae Tenebrio molitor and Onymacris marginipennis. Thresholds for absorption and "absorption capacity," which depend on ion transport by Malpighian tubules, are consistently different over the entire size range of the two species. Because of lower thresholds, uptake rates of Onymacris are over double those of Tenebrio in larvae of the same size at identical ambient water activities. By contrast, passive determinants of uptake, rectal conductance, and morphometry are similarly scaled with size in the two species. A ventilatory mechanism of vapor entry into the rectum is proposed for both species, since the anal canal is too long and narrow for exclusively diffusional entry. Vapor uptake in relation to larval mass was described by a simple diffusion model through rectal tissue, where flux varied directly with surface area and inversely with the distance between the lumen and Malpighian tubules. Failure of rectal conductance to increase proportionally with body mass means that size-specific vapor uptake declines with larval size in both species.

Water vapor absorption in insects

In common with other animals the principal examples of water transport in insects are to be found in processing food and in excretion. Some insects and other arthropods are able to absorb water vapor using preexisting buccal or rectal structures. This unique exploitation of atmospheric water depends on adequate areas for condensing water vapor and the capacity for considerable "uphill" water transport. All known uptake mechanisms depend on producing fluids of sufficiently low water activity to bring about condensation from a range of environmental humidities. In the best-understood examples (mealworms and their relatives) active KCl transport by the Malpighian tubules generates osmotic pressures sufficient to extract water from activities down to 0.88. A standing gradient model seems to describe the coupling in the tubular lumen between water flows and ion transport. Low water permeabilities and ion transport modulated with flow rate are unusual features of this coupling.

Serial sonographic monitoring of intracranial hemorrhage (ICH) and its sequelae in the preterm neonate

This study documents changes in ventricular size and brain parenchyma that occurred in 41 preterm neonates that had intracranial hemorrhage, out of 136 preterm neonates that were serially examined. Serial real-time sonographic examinations disclosed a close relationship between the severity of ICH and the development of progressive ventricular dilatation. Eighty percent of preterm neonates with minor degrees of ICH [localized subependymal hemorrhage (SEH) or SEH with small intraventricular hemorrhage (SEH/IVH)] did not develop significant ventricular dilatation, whereas all of the neonates with IVH and/or intraparenchymal hemorrhage (IPH) developed moderate or severe ventricular dilatation. Spontaneous resolution of moderate and/or severe ventricular dilatation did occur by the end of the third week of life in approximately one third of neonates with ICH. The therapeutic implications of the findings are discussed.

Ionic gradients within mantle-collar epithelial cells of the land snail Otala lactea

Aestivating Otala lactea have been shown to reduce the rate of evaporative water loss from the cells of the mantle-collar epithelium to a level comparable to that of an insect. X-ray microanalyses of ultrathin frozen sections from aestivating and non-aestivating snails have shown gradients of chloride and potassium ions in the apical microvillus region of the regulating mantle collar epithelium. The greatest difference in osmotic concentration occurs in the apical 2 micron of the cell. There appears to be a barrier at that level that prevents water being mobilised from the underlying tissues. Methods of presenting data generated by X-ray microanalysis are also discussed.

Passive exchanges during water vapour absorption in mealworms (Tenebrio molitor): a new approach to studying the phenomenon

The weights of single mealworms were continuously recorded at 20 degrees C during exposure to periods of constant humidity and to abrupt changes in atmospheric vapour pressure. Two exchange stages were recognized in each animal. Weight changes were either limited to slow losses, suggesting transpiration through the external cuticle, or showed more rapid humidity-dependent gains as well as losses. Rapid exchanges indicated that water was gained or lost through permeable barriers, from a fluid compartmet of significantly lower vapour pressure than the haemolymph, equivalent to about 90% R.H. Weight gains and losses during humidity changes provided evidence of a significant, passively exchanging fluid compartment located between the exchange surface and absorbing mechanism. Weight changes in faecal pellets following their elimination provide further support for a rectal site of atmospheric absorption.

Water regulation in aestivating snails. Ultrastructural and analytical evidence for an unusual cellular phenomenon

Aestivating snails form abundant lamellate vesicles in the cells of the mantle collar, an epithelium known to regulate the rate at which water is lost from its surface. Since lamellate vesicles are much reduced in hydrated mantle tissue of recently stimulated animals it is tentatively concluded that the vesicles, and their contents, form a barrier to water movement within these cells. X-ray microanalysis of unfixed thin sections shows that there is a concentration gradient of ions within these cells in aestivating animals which is not present in stimulated snails.

Osmotic gradients across snail epidermis: evidence for a water barrier

Cryoscopic analysis of frozen sections provided indirect evidence for the presence of a waterproof layer limiting evaporation from living epithelial cells in dormant land snails.

The Evaporation of Water From Helix Aspersa

1. Data is presented which suggest that inactive specimens of Helix aspersa are able to regulate evaporative water loss from the mantle.

2. Evaporation is reduced following the cessation of glandular extrusion, by the concentration of solutes in partially dehydrated superficial mucus.

3. Methods are described for determining vapour pressure gradients across living and freshly killed mantle tissue and for calculating permeabilities.

4. Osmotic permeability measurements using isolated and intact body wall were made.

5. The permeability of regulating mantle tissue was 0.039 mg./cm.2/hr. per mm. Hg vapour pressure difference. Living body wall and freshly killed mantle were at least forty times more permeable to water.

6. Low permeability seems to be a unique property of living mantle tissue.