An in situ single-pass perfusion model for assessing absorption across the intestinal mucosa of the brushtail possum

AIM: To develop an in situ animal model for assessing absorption of molecules across the intestinal mucosa of possums.

METHODS: A surgical preparation was used to perfuse known concentrations of reference compounds (fluorescein and luteinising hormone-releasing hormone; LHRH) through measured sections of selected regions (jejunum, caecum, proximal colon) of the intestinal tract of 19 possums, over a 2-h period. Plasma concentrations of the compounds, which were perfused either with or without co-administration of a permeation enhancer (sodium deoxycholic acid; SDA), were determined in the perfusion effluent, peripheral and in some instances in the pre-hepatic circulation by spectrofluorometry (fluorescein) or radio-immunoassay (LHRH). Pharmacokinetic parameters of both compounds in the possum were determined over a period of up to 4 h in a further 30 animals (fluorescein, n=6; LHRH n=24), from their plasma profiles following intravenous (I/V) administration of a bolus dose.

RESULTS: In animals perfused with 25 mg/ml fluorescein (Perfusion Experiment (PE) 1), the mean plasma concentration was 2.8 (SE 0.12) µg/ml in post-hepatic blood samples. When possums were perfused with 2.5 mg/ml fluorescein and 7 µg/ml LHRH (PE 2), mean plasma concentrations were 0.3 (SE 0.01) and 7.8 (SE 1.64) µg/ml fluorescein and 0.1 (SE 0.02) and 6.3 (SE 0.45) ng/ml LHRH, in the absence and presence of permeation enhancer, respectively. There was a poor correlation between pre-hepatic and post-hepatic concentrations.

CONCLUSIONS: The single-pass in situ perfusion technique provided a useful model for investigating basic information on the absorption of biocontrol agents across the intestinal tract of possums, but had limitations that must be recognised.     

The development and integrity of equine pre‐antral follicles cultured in vitro with follicle‐stimulating hormone (FSH) supplementation

This study investigated the effects of different concentrations of FSH (10, 50, 100 and 200 ng/ml) in supplemented MEM+ on the development of equine pre‐antral follicles that were cultured in vitro for 2 or 6 days. The ovaries (n = 5) from mares in seasonal anoestrus were collected from a local abattoir. Ten ovarian tissue fragments of approximately 3 × 3 × 1 mm were obtained from each animal. The fragments were cultured in situ for 2 days (D2) or 6 days (D6) in MEM+ or MEM+ supplemented with FSH at four different concentrations, establishing the following 11 groups: control (D0); MEM + (D2); MEM + (D6); MEM + 10 ng/ml of FSH (D2); MEM + 10 ng/ml of FSH (D6); MEM + 50 ng/ml of FSH (D2); MEM + 50 ng/ml of FSH (D6); MEM + 100 ng/ml of FSH (D2); MEM + 100 ng/ml of FSH (D6); MEM + 200 ng/ml of FSH (D2); and MEM + 200 ng/ml of FSH (D6). Follicles were observed in only 9.65% (388 of 4,018) of the histological sections. Of the 861 follicles evaluated, 488 were in the primordial stage, and 373 were in various developmental stages; 59.7% were morphologically normal. Regarding the integrity of the pre‐antral follicles, the groups with 100 ng/ml FSH of 2‐days culture as well as 50, 100 and 200 ng/ml FSH of 6‐days culture provided the best results. In conclusion, the in vitro culture of abattoir‐derived equine ovarian fragments presented better morphological integrity when supplemented with FSH for 6 days, in comparison with the MEM culture group. However, no clear effects were observed with FSH regarding the promotion of activation from a primordial to a developing follicle.     

Differential Rotation and Dynamics of the Solar Interior

Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes.     

Chemical Usurpation of a Nest by Paper Wasp Parasites

The paper wasp Polistes atrimandibularis is an obligatory social parasite of another Polistes species, P. biglumis bimaculatus. To control the host nest, the parasite sequentially changes the composition of its chemical signature, the cuticular hydrocarbons, during the colonial cycle. Gas chromatography-mass spectrometry of the cuticular hydrocarbons at every stage of the cycle showed that the parasite can switch on and off an entire chemical family, namely, the unsaturated hydrocarbons. In this way the parasite can match the host signature at a critical moment of the colonial cycle.     

Preliminary investigation of the effect of treating sheep during pregnancy with a vitamin A,D, E formulation on the incidence of vaginal prolapse

ABSTRACT

Aim: To determine if vitamin D₃ treatment reduced the incidence of vaginal prolapse in pregnant sheep on a North Canterbury sheep breeding property.

Methods: Pregnant ewes from a single farm were allocated to three treatment groups in May 2018. At this time, the first group (EarlyVitADE; n?=?512) received an I/M 1?mL dose of 500,000?IU/mL vitamin D₃, 60,000?IU/mL vitamin A, and 25?mg/mL vitamin E. This was repeated in July 2018, when the second group (LateVitADE; n?=?695) also received the same treatment. The third group (n?=?737) were untreated controls. All cases of vaginal prolapse on the property were recorded from pregnancy diagnosis in June 2018 until ewes were set-stocked in August 2018. The planned start of lambing was 10 August 2018.

Results: During the period of observation, vaginal prolapses were recorded in 3/699 (0.4%) 2-year-old ewes, and the odds of vaginal prolapse were not associated with treatment group in these ewes (p?>?0.3). Amongst ewes aged ≥3 years, during the same period, there were 6/333 (1.8%), 6/443 (1.4%) and 25/469 (5.3%) cases in the EarlyVitADE, LateVitADE and control groups, respectively. Compared to control ewes, the odds of vaginal prolapse were reduced in both the EarlyVitADE (OR?=?0.37; 95% CI?=?0.15–0.92) and LateVitADE (OR?=?0.25; 95% CI?=?0.10–0.62) treatment groups.

Conclusions and clinical relevance: In this preliminary study, administration of injectable vitamins A, D₃, and E to pregnant ewes reduced the incidence of vaginal prolapse during the period from pregnancy diagnosis to set-stocking on one North Canterbury hill-country farm. Due to the restricted data collection period, this investigation should be replicated to better quantify the repeatability of the observed treatment effect over the complete lambing period.     

Disease signs reported in south-eastern Australian dairy cattle while grazing Brassica species

Objective
To estimate the relative frequency of various disease signs in dairy cattle fed brassicas in south-eastern Australia, to estimate the incidence of disease signs within affected groups and to identify risk factors for commonly reported signs in brassica-fed dairy cows.
Design
A case series study and a case-control study.
Procedures
Case data was collected using an incident reporting system. Herd managers and veterinarians recorded details about disease incidents in brassica-fed dairy cattle in summer and autumn 1995 using a standard questionnaire. Potential risk factors for photosensitisation were assessed using a case-control study.
Results
Disease signs were reported in 66 groups of brassica-fed dairy cattle. Photosensitisation and bloat were the more frequently reported signs. While high incidences were reported in some groups, the incidence of disease signs was low within most affected groups. Photosensitisation occurred more frequently among groups of cows fed brassica crops treated with nitrogenous fertilisers or which were low yielding. Risks of other disease signs were greatest while the first one quarter of the crop was grazed.
Conclusions
In the study population, most disease outbreaks occurring in brassica-fed cattle were of low incidence. However, some high incidence outbreaks occurred. Results from this study suggest that important risk factors exist for disease signs in brassica-fed dairy cattle. Further studies are required if these risk factors are to be fully identified. This would allow the development of preventative strategies for high incidence disease outbreaks while feeding brassicas to dairy cattle.