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Permacol™ biological implant is a cross-linked porcine dermal collagen biomaterial that has been successfully used in abdominal wall repair. The purpose of this study is to examine biopsies of the implant after use in abdominal wall hernia repair and demonstrate its histological and immunohistochemical characteristics in vivo. Three male patients, ranging in age from 61 to 76 years, underwent biopsy of the implant and surrounding abdominal wall tissue at 16, 36, and 60 months after implantation. At 16 months, the implant demonstrated excellent tissue integration, cellular and neovascular response, and remodeling. The implant–host tissue interface showed seamless integration with no fibrosis. Tissue ingrowth into the material, new blood vessel formation, and remodeling of the host–tissue interface were observed. At approximately 36 months, organized remodeling of the implant into functional, predominately host tissue was generally seen. At more than 60 months, macroscopic and histological characteristics resembled functional human tissue with immunohistochemical evidence of the residual presence of porcine collagen. Permacol™ implant supports controlled and natural long-term remodeling into normal, functional host tissue.

This study was designed to investigate the morphological and functional status of the substance medullaris (MS) of adrenal glands (AG) in progeny of parents who smoked, in varying combinations and amounts, prior to conception. Rats were divided into groups in which either both parents or the mother only or the father only was exposed to cigarette smoke before and during pregnancy together with control groups who were not exposed to smoke at any time. The smoke exposure was calculated to be that experienced by smokers of so called “light” cigarettes. The progeny of these groups were raised to early adulthood and then the experiment was terminated. The adrenal glands of the progeny were examined for functional and morphological status. There were significant differences between the control group and all other groups–most noticeably the group in which mothers were exposed to smoke before and during pregnancy. Surprisingly there were also differences between controls and the groups where the father only had been exposed to cigarette smoke before pregnancy. This raises a whole new set of questions regarding the effect of smoke on genetic material passed form father to fetus and shows that smoking of even so called “light” cigarettes can cause visible morphological changes in progeny from matings where either or both parents have been exposed to this smoke.

The long-term success of vascular bypass graft surgery is greatly compromised by the formation of intimal hyperplasia. An established porcine model was used to investigate the pathology and mechanism resulting in intimal hyperplasia. The aim of this study was to test the specificity of several commercially available antibodies to characterise intimal hyperplasia morphology and its immunological aspects within a porcine model. After bilateral jugular vein graft into the carotid arteries in 12 pigs, vein grafts were harvested at specific time points post-surgery and fixed in 10% neutral buffered formal saline before being embedded in paraffin wax. Five-micrometer sections were cut and subjected to routine histological and immunohistochemical techniques using the ABC method. The following antibodies were tested: von Willebrand factor (vWF), CD31 markers, smooth muscle actin (α-SMC), tissue factor (TF), CD3, two CD45 markers, CD133, NFκ-β and CD68. Results showed that labelled cells were observed with vWF, α-smooth muscle actin, TF, one CD45 marker, CD3 and CD68 within the porcine model. Sections labelled with CD133 were observed in test tissue but not within the intimal hyperplasia. No positivity was observed with either CD31 markers, one vWF or one CD45 marker. In conclusion, although commercially available antibodies may not necessarily be listed as porcine specific, by using different antigen retrieval techniques, satisfactory results can be achieved.

An anal fistula has a primary track passing from an internal anal or rectal opening to an external opening in the perianal area. Surgery aims to eradicate sepsis whilst preserving faecal continence. Fistulotomy, when all tissue caudal to the primary fistulous track is opened, provides the surest method of cure but may diminish patient continence. An alternative sphincter-preserving procedure is to instill a sealant into the track. An experimental porcine model of fistula-in-ano has been developed in the Surgical Research Department at Northwick Park Institute for Medical Research. This allows histological assessment of fistula tracks after novel, sphincter-preserving surgery and treatments have been applied. Under general anaesthetic, 24 anal fistulae were created and treated, three in each of eight adult Large White/Landrace crossbred pigs. Under the same general anaesthetic, a split skin graft was taken from which to culture fibroblasts for future treatment. All tracks were treated at 4 weeks post-track induction when the tracks were established and very similar in clinical appearance to human tracks. All tracks were prepared for treatment using an instrument designed to remove granulation tissue from the wall of the track. Five control tracks were not infilled but simply had their internal and external openings closed with a Vicryl suture. Nine tracks were treated by infill using an acellular porcine dermal collagen matrix. Ten tracks were treated using a mixture of this matrix and autologous cultured fibroblasts. Histological examination of six tracks was carried out at 2 weeks, nine tracks at 2 months and nine tracks at 3 months. Histological assessment demonstrated persistent fistula tracks in only two fistulae, both of which were control tracks. All treated tracks were closed and cured at all times of examination. When autologous fibroblasts were added to the infill material, cellular integration and vascularization were improved. Using this pre-clinical model, provided fistulous tracks were prepared using a new, in-house developed instrument; treatment with acellular collagen matrix alone healed all tracks. Adding autologous fibroblasts improved the quality of wound healing. A pilot study using this treatment in human fistula patients is in progress.

The aim of this study was to assess the histological and thermal effects of different dissection technologies on tissue around incision and to consider their comparative wound healing profiles. The technologies used were Gyrus PlasmaKnife, monopolar electrode, Coblation wand, and Harmonic Scalpel. Single incisions were made using each device on the internal peritoneal surface at four test sites per porcine subject. The incision sites were assessed to determine the extent of tissue and thermal damage around the incision site in the first animal and the formation of wound cover and degree of inflammation 14 days post-procedure in the second. The PlasmaKnife was easier to handle and more controllable than the other devices and resulted in a precise incision with only localised thermal damage. The other technologies produced either deep lesions extending into the muscle and/or considerable lateral damage across the mesothelial surface. Of all the devices only the PlasmaKnife resulted in compact well-organised wound cover showing vascularisation and neo-collagenesis. The notably better wound healing profile and reduced inflammatory response seen suggest that use of the PlasmaKnife in the clinical setting may lead to reductions in both wound healing times and post-operative pain.

Pregnant rats were fed alcohol at 5 and 1.5 g/kg/day. This regime caused dose-dependent neuro-cognitive changes, biochemical changes in neocortex and changes in the morphology of neocortex and cerebellum of descendants. Comparison of different parameter changes across the groups of animals suggests dose-dependent intra-uterine developmental anomalies with considerable adaptive responses to minimal doses of alcohol consumption by mother during pregnancy.

A mouse monoclonal antibody which specifically reacts with putative blood-brain barrier (BBB) competent endothelial cells of rat cerebral capillaries was used to identify barrier competent cells in the central nervous system (CNS). The development of the cerebral capillaries and the BBB was examined and quantified, from day 6 to day 40 postpartum, using immunocytochemical and unbiased stereological techniques. There was a progressive increase in capillary formation postnatally, with collateral branching observed with progressive age. BBB development was confined to individual endothelial cells located at the periphery of the cortex until day 10 postpartum. Antibody binding progressively increased postnatally, contributing 30% of the total capillary surface area by day 20. There was a rapid elevation of reactivity from day 20 to day 40, with a mean of 83% by day 40. The BBB constitutes minimal amounts of brain vascular capillaries before day 10 of life in the rat. There is a slower increase in BBB than in total capillaries between days 10 and 20. There is a reversal of this trend between days 20 and 40.

Welcome to a significant departure for Comparative Clinical Pathology. We have been stimulated to produce this special issue by the increasing number of well-constructed manuscripts we are now receiving which are investigating changes to or maintenance of clinical pathology indices during experimental treatment with herbal extracts. Some of these manuscripts record positive changes to disease-state indices by the use of herbal extracts and others demonstrate maintenance of normal parameters during experimental induction of disease states. Diabetes, of course, is one of those conditions which is often targeted with the use of herbal extracts, and it is interesting to note that, in some remotely living and isolated tribes, diabetes is an unrecorded condition. Whether this is because of their general lifestyle or whether it reflects a diet containing medicinal herbal extracts is currently unclear, but some of the manuscripts we are now receiving at CCP are starting to investigate these questions. Herbal extract remedies (and some other natural substances) are also increasingly being investigated in areas such as wound healing both externally and internally. In this era of increasing resistance to current antibiotics and the reduction in efficacy of some of our traditional, chemistryfounded treatments, particularly for long-term conditions, investigation of alternatives including historically and currently used herbal remedies is to be encouraged and will no doubt escalate in importance as the world population increases and, concomitantly, our demands for readily available effective treatments increase. The potential to use natural herbal medicines, natural substances or extracted elements thereof is one of the components in man’s armoury against expanding intensity and numbers of both current and future disease conditions affecting both man and animals. CCP welcomes discussion of this special issue through the standard issues of Comparative Clinical Pathology and may consider further special issues in appropriate areas in the future.

Background Anorectal transplantation with pudendal nerve anastomosis after rectal excision is a possible strategy that would avoid a colostomy and recreate potentially normal anorectal function. This study investigates the technical feasibility of anorectal transplantation with pudendal nerve and inferior mesenteric artery and vein anastomosis in a porcine model. Methods Four female pigs (22–42 kg) provided donor anorectum for four male recipients (29–39 kg) under standard general anaesthesia. The donor operation involved abdominoperineal excision of rectum (APR) taking the anal sphincter, pudendal neurovascular bundle and inferior mesenteric vessels. The recipient underwent APR, transperineal introduction of the donor graft, anastomoses of the rectum, inferior mesenteric vessels and pudendal neurovascular bundle, and perineal closure. Recorded variables were duration of each step of transplantation, ischaemic time, dimensions of anastomosed structures and postoperative graft viability. Animals were killed at 24 h, the state of the graft was noted and tissue was taken for confirmatory histology. Results Mean operation time was 372 (range 303–435) min. Mean ischaemic time was 118 (100–130) min. Before death, observation at laparotomy revealed two pink grafts, one slightly dusky but healthy graft and one outright failure, reflecting the state of the mesenteric vessels, which were patent in three and thrombosed in one. Histological examination showed no difference between control biopsies and the three cases with satisfactory mesenteric flow. Gross ischaemia was present histologically in the failed case. Conclusion Anorectal transplantation is technically feasible in a pig model. Longer-term studies are now needed to assess return of function and overcome rejection issues. © 2000 British Journal of Surgery Society Ltd

Stereological Analysis of the Neocortex With Respect To Total Neuronal Number and Mean Nuclear Volume in Sudden Infant Death Syndrome (SIDS)