36 FOLLICULAR DYNAMICS IN PROLIFIC SHEEP: PGF-BASED ESTRUS SYNCHRONIZATION

A study was designed to compare the effect of a prostaglandin-based synchronization protocol on ovarian follicular dynamics in sheep with the FecB (Booroola) mutation. Forty dry Romney sheep (57.6 ± 7.3 kg; 6.1 ± 1.1 years) were randomly selected from both Invermay Booroola (BB; n = 20) and commercial (non-FecB carriers, ++; n = 20) flocks. All ewes had their estrous cycles synchronized with 2 i.m. injections of PGF (150 μg of cloprostenol, Estrumate, Schering-Plough Coopers Animal Health Ltd., New Zealand) administered 7 days apart. Ewes were monitored by transrectal ultrasonography (Aloka 900-SSD and a 7.5-MHz linear-array transducer, Aloka, Tokyo, Japan) daily from Day -2 to the day of ovulation. Data were analyzed by Student’s t-test or Wilcoxon Rank Sum test. Variances were compared with Barlett’s test. Paired t-test compared the number of preovulatory follicles in each genotype after PGF treatments and intervals from PGF to ovulation after PGF. Data are presented as mean (± SEM). The number of corpora lutea (CL) and total CL area at the time of the first and second PGF treatment were 4.4 ± 0.6; 5.7 ± 1.4 and 672.1 ± 133.5 mm2; 999.0 ± 145.9 mm2 in the BB and 2.1 ± 0.2; 2.1 ± 0.5 and 342.3 ± 60.7 mm2; 401.3 ± 68.6 mm2 in ++ ewes, respectively. These 2 variables were higher (P < 0.01) at both PGF injections in the BB than in the ++ ewes, except the CL area at the time of first PGF treatment (P = 0.15). The largest follicle diameter at the time of the first and second PGF treatments was smaller (P < 0.003) in BB (4.1 ± 0.3 mm; 3.5 ± 0.2 mm) than in ++ (5.3 ± 0.3 mm; 5.8 ± 0.1 mm) ewes. The median and mean number of follicles that ovulated after the first and second PGF treatment were higher (P < 0.0001) in BB (6 & 7; 5.7 ± 0.3; 6.9 ± 0.3; difference = 1.2 ± 0.4; P < 0.003) than in the ++ (2 & 2; 2.1 ± 0.1; 2.1 ± 0.1) sheep. The luteal area at the time of first and second PGF in both BB and ++ did not differ (P = 0.3). The intervals from the first and second PGF to the respective ovulations did not differ (P > 0.61) between BB (3.4 ± 0.2; 3.0 ± 0.3d) and ++ (3.5 ± 0.2d; 3.0 ± 0.1d) ewes. However, interval from the second PGF to ovulation was more variable (P = 0.002) in the BB than in the ++ ewes. Data of both groups were combined and a mean significant difference of 0.6 ± 0.2d (P < 0.003) was found between the first and second PGF-to-ovulation intervals. The interval from the first PGF to emergence of the next follicular wave was shorter (P < 0.02) and more variable (P < 0.03) in the BB (2.7 ± 0.4d) than in the ++ (3.5 ± 0.2 d) group. Preovulatory follicles were smaller in Booroola, but higher in number, than in ++ ewes, whereas the luteal area was similar. Within the BB ewes, the higher number of follicles that ovulated after the second PGF than after the first injection may be due to a higher follicular response to an elevated rebound in circulating FSH after the first PGF. A high number of growing follicles of the first follicular wave may also have contributed to this event. These findings warrant further research aimed at the study of the interaction between FSH and follicle dynamics in estrus synchronized sheep carrying the FecB mutation.

Chylomicron amyloid-beta in the aetiology of Alzheimer's disease

Alzheimer's disease is characterized by inflammatory proteinaceous deposits comprised principally of the protein amyloid-beta (Abeta). Presently, the origins of cerebral amyloid deposits are controversial, though pivotal for the prevention of Alzheimer's disease. Recent evidence suggests that in blood, Abeta may serve as a regulating apoprotein of the triglyceride-rich-lipoproteins and we have found that the synthesis of Abeta in enterocytes and thereafter secretion as part of the chylomicron cascade is regulated by dietary fats. It is our contention that chronically elevated plasma levels of Abeta in response to diets rich in saturated fats may lead to disturbances within the cerebrovasculature and exaggerated blood-to-brain delivery of circulating Abeta, thereby exacerbating amyloidosis. Consistent with this hypothesis we show that enterocytic Abeta is increased concomitant with apolipoprotein B48. Furthermore, cerebral extravasation of immunoglobulin G, a surrogate marker of plasma proteins is observed in a murine model of Alzheimer's disease maintained on a saturated-fat diet and there is diminished expression of occludin within the cerebrovasculature, an endothelial tight junction protein.

Three-dimensional immunofluorescent double labelling using polyclonal antibodies derived from the same species: enterocytic colocalization of chylomicrons with Golgi apparatus

Double immunolabelling is a useful technique to determine cellular colocalization of proteins, but is prone to false-positive staining because of cross-reactivity between antibodies. In this study, we established a simple and quick method to demonstrate the immunofluorescent double labelling with two rabbit-derived polyclonal antibodies. The principle used was to establish a dilution of primary antibody for the first protein of interest, which would only be detectable following biotin-avidin amplification. Thereafter, the second protein of interest was assessed via standard secondary antibody detection, ensuring no cross-reactivity with the first protein antibody-antigen complex. We successfully demonstrated the three-dimensional colocalization of enterocytic apolipoprotein B, an equivocal marker of intestinal lipoproteins with Golgi apparatus. Colocalization of apo B and Golgi apparatus (75.2 +/- 8.5%) is consistent with the purported mode of secretion of these macromolecules.

Strategy for genotoxicity testing: Hazard identification and risk assessment in relation to in vitro testing

This report summarizes the proceedings of the September 9-10, 2005 meeting of the Expert Working Group on Hazard Identification and Risk Assessment in Relation to In Vitro Testing, part of an initiative on genetic toxicology. The objective of the Working Group was to develop recommendations for interpretation of results from tests commonly included in regulatory genetic toxicology test batteries, and to propose an appropriate strategy for follow-up testing when positive in vitro results were obtained in these assays. The Group noted the high frequency of positive in vitro findings in the genotoxicity test batteries with agents found not to be carcinogenic and thought not to pose a carcinogenic health hazard to humans. The Group agreed that a set of consensus principles for appropriate interpretation and follow-up testing when initial in vitro tests are positive was needed. Current differences in emphasis and policy among different regulatory agencies were recognized as a basis of this need. Using a consensus process among a balanced group of recognized international authorities from industry, government, and academia, it was agreed that a strategy based on these principles should include guidance on: (1) interpretation of initial results in the "core" test battery; (2) criteria for determining when follow-up testing is needed; (3) criteria for selecting appropriate follow-up tests; (4) definition of when the evidence is sufficient to define the mode of action and the relevance to human exposure; and (5) definition of approaches to evaluate the degree of health risk under conditions of exposure of the species of concern (generally the human). A framework for addressing these issues was discussed, and a general "decision tree" was developed that included criteria for assessing the need for further testing, selecting appropriate follow-up tests, and determining a sufficient weight of evidence to attribute a level of risk and stop testing. The discussion included case studies based on actual test results that illustrated common situations encountered, and consensus opinions were developed based on group analysis of these cases. The Working Group defined circumstances in which the pattern and magnitude of positive results was such that there was very low or no concern (e.g., non-reproducible or marginal responses), and no further testing would be needed. This included a discussion of the importance of the use of historical control data. The criteria for determining when follow-up testing is needed included factors, such as evidence of reproducibility, level of cytotoxicity at which an increased DNA damage or mutation frequency is observed, relationship of results to the historical control range of values, and total weight of evidence across assays. When the initial battery is negative, further testing might be required based on information from the published literature, structure activity considerations, or the potential for significant human metabolites not generated in the test systems. Additional testing might also be needed retrospectively when increase in tumors or evidence of pre-neoplastic change is seen. When follow-up testing is needed, it should be based on knowledge about the mode of action, based on reports in the literature or learned from the nature of the responses observed in the initial tests. The initial findings, and available information about the biochemical and pharmacological nature of the agent, are generally sufficient to conclude that the responses observed are consistent with certain molecular mechanisms and inconsistent with others. Follow-up tests should be sensitive to the types of genetic damage known to be capable of inducing the response observed initially. It was recognized that genotoxic events might arise from processes other than direct reactivity with DNA, that these mechanisms may have a non-linear, or threshold, dose-response relationship, and that in such cases it may be possible to determine an exposure level below which there is negligible concern about an effect due to human exposures. When a test result is clearly positive, consideration of relevance to human health includes whether other assays for the same endpoint support the results observed, whether the mode or mechanism of action is relevant to the human, and - most importantly - whether the effect observed is likely to occur in vivo at concentrations expected as a result of human exposure. Although general principles were agreed upon, time did not permit the development of recommendations for the selection of specific tests beyond those commonly employed in initial test batteries.

Fasciitis ossificans with a radial neuropathy: a benign differential diagnosis for soft tissue sarcoma

A soft tissue mass with an associated neuropathy suggests a malignancy with nerve compression or infiltration. However, there are benign diagnoses to consider. We report a case of an axillary mass with a radial nerve neuropathy, initially suspected to be a soft tissue sarcoma. The final diagnosis was fasciitis ossificans. This is the first such reported case. The presence of severe pain and tenderness suggested an inflammatory process. Fasciitis ossificans is a rare form of heterotopic bone formation, commonly presenting with signs of local inflammation or pain.

A review of an anaesthetic led vascular access list

The demand for insertion of long-term central venous (Hickman type) catheters is thought to be increasing. Organisation is required to meet this demand in a safe and efficient manner. This report reviews the results from a dedicated, anaesthetic led vascular access list over the initial 61-month period. One thousand procedures were performed. Nine hundred and twenty catheters were inserted under local anaesthesia, with or without intravenous sedation and analgesia. Eighty catheters were removed. All procedures were performed during a dedicated once weekly, morning list. A total of 53% of all procedures were performed on a day-case basis, 43% on in-patients. Only 1.5% of patients required an unexpected overnight stay (usually medically unfit patients). There were 81 (9%) cancellations on the day of procedure due to neutropaenia, pneumonia or urinary tract infections. Ultrasound guidance was used initially selectively in 14%, latterly in 100% of procedures and fluoroscopy in all insertions to confirm or adjust catheter position. This service has been well received by patients and oncology services. In addition it provides an interesting area of practice for anaesthetists and an ideal environment for teaching more advanced aspects of central venous access. It may provide a template of service for other centres.

Ultrasound imaging of the axillary vein--anatomical basis for central venous access

BACKGROUND

The central veins that are usually cannulated are the jugular, subclavian, femoral and brachial. If subclavian catheterization is difficult using surface landmark techniques, we now use ultrasound to catheterize the infraclavicular axillary vein. This approach is not widely used and the ultrasound appearance has not been formally described. We examined the anatomical relationships of the axillary vessels to guide safe cannulation of the axillary vein.

METHOD

In 50 subjects, we used ultrasound to examine the infraclavicular regions from below the mid-clavicular point and at 2 cm and 4 cm further laterally (described as the middle and lateral points) with the arms at 0 degrees, 45 degrees and at 90 degrees abduction. We took measurements at each point, with the artery and vein seen in cross-section. The depth from the skin, vessel diameters and the distance between the vessels was measured. The amount of overlap was scaled from 0 (no overlap) to 3 (complete overlap). We also recorded (if visible) the distance between the rib cage and axillary vein. A longitudinal image of the vein was also obtained. Angle of ascent (in relation to the skin), length and depth of the vein was measured.

RESULTS

Axillary vessels were seen in 93% of images. The mean depth from skin to vein increased from 1.9 cm (range 0.7-3.7 cm) medially to 3.1 cm (1.1-5.6 cm) laterally. The venous diameter decreased from 1.2 cm (0.3-2.1 cm) medially to 0.9 cm (0.4-1.6 cm) laterally. The arterio-venous distance increased from 0.3 cm to 0.8 cm. Median arterio-venous overlap decreased from 2/3 (mode 3/3) to 0 (0). The distance from rib cage to vein increased from 1.0 cm to 2.0 cm.

CONCLUSION

The axillary vein is an alternative for central venous cannulation and we present an anatomical rationale for its safe use. Less arterio-venous overlap and a greater distance between artery and vein and from vein to rib cage should provide an increased margin of safety for central venous cannulation.

Preeclampsia complicated by placental abruption, HELLP, coagulopathy and renal failure – further lessons

We present a case of preeclampsia complicated by HELLP (haemolysis, elevated liver enzymes and low platelets) syndrome and marked coagulopathy. The severity of the coagulopathy and haemolysis made renal failure and pulmonary oedema inevitable. We identified a number of discussion points in this case. These were the delay to appreciate the haemolysis, the severity of the haemolysis and its interaction with the treatment of coagulopathy and the conservative management of pulmonary oedema. At these points there were shortcomings in our management of this complex case that merit further discussion.

Safe removal of long-term cuffed Hickman-type catheters

The use of long-term venous access devices is increasing. Most devices are anchored by a cuff, usually made of Dacron. The disadvantage of such cuffs is that a cut-down procedure is required for their removal. This article presents a simple technique for removal of Hickman-type catheters, emphasizing avoidance of complications.

Information needs and preference for information of women with breast cancer over a first course of radiation therapy

The study assessed the information needs of women receiving a course of radiation therapy (RT) for breast cancer and the relationship between information needs and preference for information. Thirty-three women were interviewed during the first (T1), third (T2), and last week of RT (T3), and one month later (T4) using the Toronto Informational Needs Questionnaire--Breast Cancer and the Information Subscale of the Health Opinion Survey. Information need scores were high and did not differ significantly across time. Information need and preference for information were correlated only at T1. Findings indicate that women with breast cancer receiving RT have high information needs and preference for information may not be a meaningful indicator of their desire for information. Health care providers need to assess the women's information needs frequently and be prepared to offer on-going educational support.

Discharge information needs and symptom distress after abdominal aortic surgery

The purpose of this study was to describe the discharge information needs and symptom distress of people after abdominal aortic reconstructive surgery. Interviews (N = 51) were conducted prior to, and 4 weeks after, hospital discharge. People indicated that the most important information to help them manage their care after discharge related to the recognition, prevention and management of complications. Broken sleep and incisional pain were the most distressful of symptoms prior to hospital discharge, whereas fatigue and broken sleep were most distressful once home. These results may assist nurses to understand the discharge information needs and symptom distress of people recovering from aortic reconstructive surgery and the importance of discharge education to help people to manage their care once home.

Catecholamines contribute to exertional dyspnoea and to the ventilatory response to exercise in normal humans

BACKGROUND

Exogenous catecholamine administration in humans stimulates ventilation. The present study was designed to investigate whether increased endogenous catecholamine release influences objective measures of ventilation and subjective measures of breathlessness in normal subjects.

METHODS

Yohimbine, a pre-synaptic alpha 2 adrenoceptor antagonist, or placebo was administered to 10 normal male subjects in a double-blind cross-over fashion. Ventilation and metabolic gas exchange were measured during steady state exercise at 60% of previously determined maximal oxygen consumption. Venous lactate and noradrenaline were measured during exercise. Subjects' sensation of breathlessness and fatigue were recorded using visual analogue scales.

RESULTS

Plasma noradrenaline was higher following yohimbine administration (at 6 min exercise; 4.58 +/- 0.56 nmol.l-1 vs 8.74 +/- 1.53; P < 0.05). Oxygen consumption was unchanged, but ventilation was greater throughout exercise following yohimbine. The sensation of exertion was greater following yohimbine, and at any given level of ventilation, the sensation of exertion was greater.

CONCLUSIONS

Yohimbine administration causes increased noradrenaline release. This is associated with an increased ventilatory response and an increase in the sensation of exertion during steady state exercise. An increase in circulating noradrenaline might be a mechanism for both increased ventilation and pathological conditions of breathlessness such as chronic heart failure.