Evaluation of delayed timing of artificial insemination with sex-sorted sperm on pregnancy per artificial insemination in seasonal-calving, pasture-based lactating dairy cows.

The objective was to use ovulation synchronization with timed artificial insemination (TAI) to evaluate the effect of timing of artificial insemination (AI) with frozen sex-sorted sperm on fertility performance in pasture-based compact calving herds. Ejaculates from 3 Holstein-Friesian bulls were split and processed to provide frozen sex-sorted sperm (SS) at 4 × 106 sperm per straw, and frozen conventional sperm at 15 × 106 sperm per straw (CONV). A modified Progesterone-Ovsynch protocol was used for estrous synchronization, with TAI occurring 16 h after the second GnRH injection for cows assigned to CONV, and either 16 h (SS-16) or 22 h (SS-22) for cows assigned to SS. Pregnancy diagnosis was conducted by transrectal ultrasound scanning of the uterus 35 to 40 d after TAI (n = 2,175 records available for analysis). Generalized linear mixed models were used to examine the effects of treatment on pregnancy per artificial insemination (P/AI). Fixed effects included treatment (n = 3), bull (n = 3), treatment by bull interaction, parity (n = 4), days-in-milk category (n = 3), and treatment by days-in-milk category, with herd (n = 24) included as a random effect. Pregnancy per AI was greater for CONV compared with both SS-16 and SS-22 (61.1%, 49.0%, and 51.3%, respectively), and the SS treatments did not differ from each other (relative P/AI for SS-16 and SS-22 vs. CONV were 80.2% and 84.0%, respectively). There were significant bull and treatment by bull interaction effects. Additional analysis was undertaken using a model that included herd as a fixed effect. This analysis identified marked herd-to-herd variation (within-herd relative P/AI for the combined SS treatments vs. CONV ranged from 48-121%). The tertile of herds with the best performance achieved a mean relative P/AI of 100% (range = 91-121%), indicating that P/AI equivalent to CONV is achievable with SS. Conversely, the tertile of herds with the poorest performance achieved a mean relative P/AI of 67% (range = 48-77%). We found that SS resulted in poorer overall P/AI compared with CONV sperm regardless of timing of AI. Marked variation existed between herds; however, one-third of herds achieved P/AI results equal to CONV. Identification of factors responsible for the large herd-to-herd variation in P/AI with SS, and development of strategies to reduce this variation, warrant further research.

Fertility of frozen sex-sorted sperm at 4 × 106 sperm per dose in lactating dairy cows in seasonal-calving pasture-based herds.

The objective was to evaluate the reproductive performance of frozen sex-sorted sperm at 4 × 106 sperm per dose (SexedULTRA 4M, Sexing Technologies, Navasota, TX) relative to frozen conventional sperm in seasonal-calving pasture-based dairy cows. Semen from Holstein-Friesian (n = 8) and Jersey (n = 2) bulls was used. Four of the Holstein bulls used were resident at or near a sex-sorting laboratory (Cogent, UK, or ST Benelux, the Netherlands). The remaining 6 bulls were located at studs in Ireland. For these 6 bulls, ejaculates were collected, diluted with transport medium, and couriered to Cogent in parcel shippers. Transit time from ejaculation to arrival at the sorting laboratory was 6 to 7 h. For all bulls, ejaculates were split and processed to provide frozen conventional sperm (CONV) at 15 × 106 sperm per straw and frozen sex-sorted (SS) sperm at 4 × 106 sperm per straw and used to inseminate lactating dairy cows after spontaneous estrus. Pregnancy diagnosis was performed by ultrasound scanning (n = 7,246 records available for analysis). Generalized linear mixed models were used to examine effects on pregnancy per AI (P/AI) at first artificial insemination, with sperm treatment (CONV vs. SS), bull (n = 10), and treatment × bull interaction as the fixed effects, and herd (n = 142) as a random effect. Overall, P/AI was greater for cows inseminated with CONV than for those inseminated with SS (59.9% vs. 45.5%; 76.0% relative to CONV). This study was not designed to compare resident bulls vs. shipped ejaculates, but the magnitude of the difference between P/AI achieved by CONV and SS was apparently less for resident bulls (60.3% vs. 50.2%) than for shipped ejaculates (58.6% vs. 40.7%). We discovered a treatment × bull interaction for shipped ejaculates (P/AI ranged from 45 to 86% relative to CONV) but not for the resident bulls (P/AI ranged from 81 to 87% relative to CONV). Relative P/AI of SS compared with CONV was greater in cows with high or average fertility potential (76.1% and 78.3%, respectively) than in cows with low fertility potential (58.1%). In 33.1% of the enrolled herds, the P/AI achieved with SS was 90% or more of the P/AI achieved with CONV; this was mainly explained by herds in which SS performed exceptionally well but CONV performed poorly. In conclusion, SS had lower overall P/AI compared with CONV; however, P/AI achieved with SS was dependent on the bull, fertility potential of the cow, and herd. Strategies to improve the P/AI with SS in seasonal-calving pasture-based lactating dairy cows require further research.

The relationship between anogenital distance and fertility, and genome-wide associations for anogenital distance in Irish Holstein-Friesian cows.

The evaluation of anogenital distance (AGD), the distance from the center of the anus to base of the clitoris, as a potential fertility trait for genetic selection in dairy cows has generated recent interest. The objectives of this cross-sectional observational study were to (1) characterize the distribution and variability of AGD, (2) determine factors associated with AGD, (3) estimate heritability for AGD, (4) identify single nucleotide polymorphisms (SNP) associated with phenotypic variation of AGD, and (5) validate the relationship between categories of AGD and fertility in Irish Holstein-Friesian cows. Anogenital distance was measured using digital calipers in 1,180 Holstein cows (mean ± standard deviation: 225 ± 79 d in milk) from 10 dairy herds located in Munster, Ireland. In addition, age (yr), weight (kg), height at hip (cm), and body condition score (BCS) at the time of AGD measurement were determined in a subset of 281 cows. Genotype information available from 908 cows was subsequently imputed to the Illumina Bovine High Density BeadChip (Illumina Inc., San Diego, CA) for genome-wide association analysis of phenotypic variation in AGD. Overall, AGD had a normal distribution and high variability (mean ± standard deviation; 119.2 ± 11.6 mm). Anogenital distance was weakly but positively associated with cow age, hip height, and body weight, and negatively associated with BCS; the phenotypic variation in AGD that was explainable by these variables was small (coefficient of determination; R2 = 0.09, 0.06, 0.10, and 0.02, respectively). The estimated heritability for AGD was 0.37 (standard error of mean ± 0.08). Six SNP of suggestive significance were identified on Bos taurus autosomes 6, 15, 20, and 26; however, none of these SNP was related to previously identified candidate genes for fertility. Cows were categorized into quartiles (Q1; 86 to 111 mm; n = 311, Q2; 112 to 120 mm; n = 330; Q3; 121 to 127 mm; n = 265, and Q4; 128 to 160 mm; n = 274) based on AGD and the association with reproductive outcomes examined (21-d submission rate, pregnancy to first AI, pregnancy rate within 21, 42 and 84-d after the farm mating start date, and number of times bred). None of the reproductive variables differed significantly between AGD categories. In summary, despite identification of high variability and moderate heritability for AGD in Irish Holstein-Friesian cows, reproductive outcomes did not differ between categories of AGD. This latter result differs from our previous finding of an inverse relationship between AGD and pregnancy outcomes in first- and second-parity Canadian Holstein cows, emphasizing the need to test and validate this new phenotype in diverse cow populations.

Review: Applications and benefits of sexed semen in dairy and beef herds.

The use of sexed semen in dairy and beef cattle production provides a number of benefits at both farm and industry levels. There is an increasing demand for dairy and beef products across the globe, which will necessitate a greater focus on improving production efficiency. In dairy farming, there is surplus production of unwanted male calves. Male dairy calves increase the risk of dystocia compared with heifer calves, and as an unwanted by-product of breeding with conventional semen, they have a low economic value. Incorporating sexed semen into the breeding programme can minimise the number of unwanted male dairy calves and reduce dystocia. Sexed semen can be used to generate herd replacements and additional heifers for herd expansion at a faster rate from within the herd, thereby minimising biosecurity risks associated with bringing in animals from different herds. Furthermore, the use of sexed semen can increase herd genetic gain compared with use of non-sorted semen. In dairy herds, a sustainable breeding strategy could combine usage of sexed semen to generate replacements only, and usage of beef semen on all dams that are not suitable for generating replacements. This results in increased genetic gain in dairy herd, increased value of beef output from the dairy herd, and reduced greenhouse gas emissions from beef. It is important to note, however, that even a small decrease in fertility of sexed semen relative to conventional semen can negate much of the economic benefit. A high fertility sexed semen product has the potential to accelerate herd expansion, minimise waste production, improve animal welfare and increase profitability compared with non-sorted conventional semen.

Effect of seminal plasma from high- and low-fertility bulls on cauda epididymal sperm function.

The aim of this study was to characterise the effect of seminal plasma (SP) from bulls of high or low fertility on sperm function. First, the effect of SP on the motility of fresh cauda epididymal spermatozoa (CES) and frozen-thawed ejaculated spermatozoa was assessed (Experiment 1a). Seminal plasma was then collected from bulls of known high and low fertility. Pooled CES were incubated in the SP from each bull, diluted and assessed for motility and viability on Days 1, 2, 3 and 5 after packaging as fresh semen (Experiment 1b). Also assessed were motility, kinematics, viability and mitochondrial membrane potential after thawing (Experiment 1c) as well as hypotonic resistance (Experiment 2) and fertilisation potential using in vitro fertilisation (Experiment 3). Seminal plasma increased the motility of CES (P<0.05); however, there was no effect of SP on the motility and viability of fresh CES or on CES post-thaw motility, viability and mitochondrial membrane potential (P>0.05). The hypotonic resistance of CES was reduced by SP (P<0.05), irrespective of whether the SP was from high- or low-fertility bulls. Seminal plasma from high- or low-fertility bulls had no effect on cleavage or blastocyst rates (P>0.05). In conclusion, SP affects the physiological function of CES but there is no difference between SP from high- or low-fertility bulls.

In vitro addition of docosahexaenoic acid improves the quality of cooled but not frozen-thawed stallion semen.

The aim of the present study was to assess the effect of the addition of docosahexaenoic acid (DHA) on the in vitro quality of cooled and frozen-thawed stallion semen. In Experiment 1, semen from 10 stallions was collected (three ejaculates per stallion). Semen was diluted to 100×106 spermatozoa mL-1 with 0.02mM vitamin E (VE) and 0, 1, 10 or 20ng mL-1 DHA and frozen. Semen was thawed and total motility (TM), rapid progressive motility (PM), acrosome integrity, membrane fluidity and morphology were assessed. In Experiment 2, semen from three stallions was collected (three ejaculates per stallion) and frozen as in Experiment 1, but VE and DHA were added after thawing. TM and PM were assessed at 30, 60 and 120min and viability, acrosome integrity and membrane fluidity were evaluated at 30min. In Experiment 3, semen from five stallions was collected (one to three ejaculates per stallion), diluted to 20×106 spermatozoa mL-1 and stored at 4°C. After 1, 24, 48 and 72h, TM, PM, viability, membrane fluidity and lipid peroxidation were assessed. The addition of DHA had no effect on frozen semen (Experiments 1 and 2) but improved TM, PM and membrane fluidity in cooled stallion semen.

Dietary polyunsaturated fatty acid supplementation of young post-pubertal dairy bulls alters the fatty acid composition of seminal plasma and spermatozoa but has no effect on semen volume or sperm quality.

The aim of this study was to examine the effects of dietary supplementation with rumen protected n-6 or n-3 polyunsaturated fatty acids (PUFA) on the quantity and quality of semen from young post-pubertal dairy bulls. Pubertal Holstein-Friesian (n = 43) and Jersey (n = 7) bulls with a mean ± s.e.m. age and bodyweight of 420.1 ± 5.86 days and 382 ± 8.94 kg, respectively, were blocked on breed, weight, age and semen quality (based on the outcomes of two pre-trial ejaculates) and randomly assigned to one of three treatments: (i) a non-supplemented control (CTL, n = 15), (ii) rumen-protected safflower (SO, n = 15), (iii) rumen-protected n-3 PUFA-enriched fish oil (FO, n = 20). Bulls were fed their respective diets, ad libitum for 12 weeks; individual intakes were recorded using an electronic feeding system for the initial 6 weeks of the feeding period. Semen was collected via electro-ejaculation at weeks -2, -1, 0, 7, 10, 11 and 12 relative to the beginning of the trial period (week 0). On collection, semen volume, sperm concentration and progressive linear motility (PLM) were assessed. On weeks -2, -1, 0, 10, 11, 12, semen was packaged into 0.25 mL straws and frozen using a programmable freezer. On weeks -1, 7 and 11; a sub-sample of semen was separated into sperm and seminal plasma, by centrifugation and stored at - 20 °C until analysis of lipid composition. Semen from 10 bulls per treatment were used for post-thaw analysis at weeks 10, 11 and 12 (3 straws per ejaculate). Sperm motility was analysed by computer assisted semen analysis (CASA). In addition, membrane fluidity, acrosome reaction and oxidative stress were assessed using flow cytometry. Sperm from bulls fed SO had a 1.2 fold higher total n-6 PUFA content at week 11 compared to week -1 (P < 0.01) while bulls fed FO had a 1.3 fold higher total n-3 PUFA content, in sperm by week 11 (P < 0.01). There was no effect of diet on semen volume, concentration or PLM of sperm when assessed either immediately following collection or post-thawing. Membrane fluidity and oxidative stress of sperm were also not affected by diet. The percentage of sperm with intact-acrosomes was lower in CTL bulls compared to those fed SO (P < 0.01). In conclusion, while the lipid composition of semen was altered following dietary supplementation with either n-6 or n-3 based PUFA, this did not lead to measurable improvements in the quantity or quality of semen produced by young post-pubertal dairy bulls.

Relationship between in vitro sperm functional assessments, seminal plasma composition, and field fertility after AI with either non-sorted or sex-sorted bull semen.

The hypothesis of this study was that different in vitro parameters are required to predict the in vivo fertility of non-sorted (NS) and sex-sorted (SS) semen. Thus, the aim was to correlate in vitro bull sperm functional parameters (experiment 1) and seminal plasma composition (experiment 2) with pregnancy rates using 2 cohorts of bulls (NS and SS). Experiment 1: ejaculates from each bull (n = 3 ejaculates per bull; n = 6 bulls for both NS and SS) were assessed for motility, thermal stress tolerance and morphology using microscopy, and viability, osmotic resistance, mitochondrial membrane potential, and acrosome integrity using flow cytometry. Fertilizing ability was assessed using IVF. Experiment 2: ejaculates (n = 3 per bull; n = 8 and 6 bulls for NS and SS, respectively) were collected, seminal plasma harvested and frozen and later analyzed for amino acid and fatty acid composition using gas chromatography mass spectrometry. In the NS cohort of bulls, there was no correlation between pregnancy rate and any of the sperm functional parameters assessed. However, within the SS cohort, motility and viability were correlated with pregnancy rate (r = 0.84 and 0.80, respectively; P < 0.05). There was no correlation between IVF outcome and pregnancy rate in either the SS or NS cohort of bulls. In the NS cohort of bulls, concentrations of the amino acid isoleucine and the fatty acid tricosylic acid (C23:0) were correlated with pregnancy rate (r = 0.80 and 0.74, respectively; P < 0.05). Within the SS cohort of bulls, the amino acid glutamic acid and the fatty acid arachidic acid (C20:0) were correlated with pregnancy rate (r = 0.84 and 0.82, respectively; P < 0.05). In conclusion, this study suggests that different in vitro markers of fertility are required to predict the fertility of NS and SS sperm.

Cholesterol-loaded-cyclodextrins improve the post-thaw quality of stallion sperm.

An unacceptable proportion of stallion sperm do not survive the freeze-thaw process. The hypothesis of this study was that adding cholesterol to a stallion semen extender would stabilise the sperm membrane, resulting in an improved post-thaw semen quality in terms of increased sperm viability, membrane integrity and fluidity, and reduced oxidative stress. Semen was collected from three stallions and diluted in four extenders: TALP; TALP+0.75mg methyl-ß-cyclodextrin-cholesterol (MßCD)/mL (MßCD0.75); TALP+1.5mg MßCD-cholesterol/mL (MßCD1.5); and Equipro. Following 15min incubation, samples were centrifuged and diluted to 100×10(6)sperm/mL, frozen in 0.5mL straws and stored in liquid nitrogen. Sperm from each treatment was assessed for progressive linear motility (PLM) and acceptable membrane integrity under hypotonic conditions on a phase contrast microscope at 1000× while viability, membrane fluidity and superoxide generation were assessed by flow cytometry. The MßCD1.5 and MßCD0.75 treatments had a greater proportion of viable sperm than the TALP treatment (P<0.01). There was no effect of treatment on PLM or membrane integrity. The MßCD1.5 treatment had a greater proportion of viable sperm positive for membrane fluidity than the TALP treatment (P<0.05). The MßCD1.5 and MßCD0.75 treatments had a lesser proportion of viable sperm positive for superoxide generation than the TALP treatment (P<0.001). This study has demonstrated that adding cholesterol to stallion sperm prior to cryopreservation increases post-thaw viability, with these viable sperm being of better quality in terms of increased membrane fluidity and reduced superoxide generation.

Bimodal electric tissue ablation (BETA) - in-vivo evaluation of the effect of applying direct current before and during radiofrequency ablation of porcine liver.

AIM: To examine the effect of applying increasing amounts of direct current (DC) before and during alternating current radiofrequency ablation of porcine liver. MATERIALS AND METHODS: Using a Radiotherapeutics RF3000 generator, a 9 V AC/DC transformer and a 16 G plain aluminium tube as an electrode, a control group of 24 porcine hepatic radiofrequency ablation zones was compared with 24 zones created using a bimodal electric tissue ablation (BETA) technique in three pigs. All ablations were terminated when tissue impedance rose to greater than 999 Omega or radiofrequency energy input fell below 5 W on three successive measurements taken at 1 min intervals. BETA ablations were performed in two phases: an initial phase of variable duration DC followed by a second phase during which standard radiofrequency ablation was applied simultaneously with DC. During this second phase, radiofrequency power input was regulated by the feedback circuitry of the RF3000 generator according to changes in tissue impedance. The diameters (mm) of each ablation zone were measured by two observers in two planes perpendicular to the plane of needle insertion. The mean short axis diameter of each ablation zone was subjected to statistical analysis. RESULTS: With increased duration of prior application of DC, there was a progressive increase in the diameter of the ablation zone (p<0.001). This effect increased sharply up to 300 s of pre-treatment after which a further increase in diameter occurred, but at a much lesser rate. A maximum ablation zone diameter of 32 mm was produced (control diameters 10-13 mm). CONCLUSION: Applying a 9 V DC to porcine liver in vivo, and continuing this DC application during subsequent radiofrequency ablation, results in larger ablation zone diameters compared with radiofrequency ablation alone.

Postoperative death in sows as a result of gastric mucosal de-gloving at the pars oesophagea.

It is well documented that pigs frequently die from postoperative acute gastric dilatation, and proximal gastric 'stress' ulceration. Three cases of gastric mucosal 'de-gloving' are reported. This was secondary to acute gastric dilatation and resulted in death from acute haemorrhage. All animals had undergone major abdominal surgery. Histology confirmed that the proximal gastric mucosa had been 'de-gloved', or torn from the gastro-oesophageal junction, leaving exposed muscle fibres. This syndrome has not been reported previously. The postmortem appearances of this mechanical injury could easily be mistaken for extensive oesophago-gastric peptic ulceration. This has major implications for prevention.

Endoscopic perductal electrolytic ablation of the pancreas: experimental studies of morbidity and mortality.

BACKGROUND: Palliation of pancreatic cancer remains the only option for the majority of patients. Palliative techniques such as surgical bypass and endoscopic retrograde cholangiopancreatography (ERCP) with stenting are not ideal. The 'ideal' palliative technique would combine the efficacy of surgery with the minimal complications of an endoscopic procedure. Endoscopically delivered perductal electrolytic ablation of pancreatic lesions has the potential to meet these criteria. METHODS: Fifteen pigs were used. The pancreatic duct was cannulated with an electrolysis catheter. Animals were randomised to either: controls, treatment 2-week survivor or treatment 8-week survivor. An electrolytic dose was administered to the treatment animals. Post-operatively, serum amylase and leucocyte count were assessed. Pancreata were histologically examined to detect evidence of acute pancreatitis. RESULTS: Electrolysis was well tolerated. There was no difference in post-operative hyperamylasaemia and leucocyte count between the groups. Histological examination showed inflammation at the ablation site at 2 weeks, by 8 weeks this was replaced by scarring. CONCLUSION: The results of this study suggest that endoscopic perductal electrolytic ablation of the pancreas is feasible and safe. Biochemical and histological findings indicate self-limiting localised inflammation of the pancreas. This technique may have a role in the palliation of pancreatic cancer and warrants further investigation.

Electrolytic liver ablation is not associated with evidence of a systemic inflammatory response syndrome.

BACKGROUND: Local ablation has been proposed for treatment of liver tumours. Cryoshock, a variant of the systemic inflammatory response syndrome (SIRS), is a potentially fatal complication of cryoablation caused by systemic release of necrotic breakdown products from ablated liver. The proinflammatory cytokines tissue necrosis factor (TNF) alpha and interleukin (IL) 1 are important mediators of this response. This study assessed the risk of SIRS complicating electrolytic liver ablation by measuring circulating levels of inflammatory cytokines, other inflammatory markers and clinical markers of organ function. METHODS: Electrolytic liver ablation was performed in 16 pigs and four pigs served as controls. Platelet count, and serum levels of urea, creatinine, liver enzymes, C-reactive protein (CRP), TNF-alpha and IL-1beta were measured before treatment and for 72 h after the procedure. RESULTS: There were significant dose-related increases in CRP and alanine aminotransferase levels with liver electrolysis. There was no significant derangement in renal function or platelet count following ablation. A rise in serum TNF-alpha and IL-1beta levels was not associated with liver electrolysis. CONCLUSION: There was no evidence of organ failure or significantly raised levels of proinflammatory cytokines as a result of liver electrolysis, suggesting that this is a safe procedure for liver ablation.

Perductal electrolytic ablation of the porcine pancreas: a minimally invasive option-studies of morbidity and mortality.

BACKGROUND: Pancreatic cancer has a dismal prognosis. Few patients are suitable for surgical resection, leaving the majority requiring symptom palliation. Current palliative techniques such as surgical bypass and endoscopic retrograde cholangiopancreatography (ERCP) are imperfect. A novel palliative therapy combining the symptom control of surgical bypass with the minimally invasive nature of ERCP is required. METHODS: Perductal electrolytic ablation of pancreatic tissue, in a porcine model, was performed. There were two survival groups of 2 weeks (n = 4) and 8 weeks (n = 4). Postoperatively, serum biochemistry, amylase and C-reactive protein (CRP) were assessed. Histological examination of the pancreas, lungs, and kidneys was performed to determine the presence of acute pancreatitis or systemic inflammatory response. RESULTS: An immediate transient increase in both amylase and CRP was seen. Although pancreatic histology demonstrated localised necrosis at the electrolytic site at 2 weeks, there was no evidence of generalized pancreatitis or a systemic inflammatory response at either 2 or 8 weeks. CONCLUSIONS: This study suggests that, although there is localized pancreatic necrosis and transient hyperamylasemia, perductal pancreatic electrolytic ablation is safe, with neither generalized pancreatitis nor a systemic inflammatory response, in the medium and long term. Although performed in normal porcine pancreas, because of the absence of a large-animal model of pancreatic cancer, this study suggests that electrolytic pancreatic ablation is safe. This technique may have a role in the palliation of pancreatic cancer, especially if delivered via a minimally, invasive approach, and warrants further investigation.

Segmental nature of the porcine liver and its potential as a model for experimental partial hepatectomy.

BACKGROUND: In-depth knowledge of pig liver anatomy allows potential research into segmental liver resections and hepatic regeneration, as well as liver transplantation techniques. The segmental anatomy, however, remains largely unknown. This study aimed to delineate the segmental anatomy of the porcine liver in comparison with that of the human. METHODS: The segmental anatomy of the porcine liver was determined using acrylic injection casting of ex vivo pig livers, allowing the arterial, venous and biliary supply to be visualized directly. This was correlated using multi-slice computed tomography (CT) and three-dimensional reconstructions. RESULTS: Although the external morphology of the porcine liver differs from that of the human, the segmental anatomy is remarkably similar in term of its vascularity and biliary tree. CONCLUSION: Acrylic casting of the porcine liver accurately delineates the vascular and biliary anatomy, and is a useful tool for performing experimental liver surgery. The similarities between porcine and human segmental anatomy allow domestic swine to be used as a comparable model. Three-dimensional CT reconstructions can also accurately visualize the anatomy and may be used to perform virtual surgery, or to assess segmental volumes.

Palliation of pancreatic cancer using electrolytic ablation.

BACKGROUND: Inoperable pancreatic cancer has a dismal prognosis. Palliation involves either stenting or surgical bypass. Stenting does not relieve gastric outlet obstruction, and surgical bypass is a major procedure. A minimally invasive procedure is needed that relieves both gastric outlet and biliary obstruction, with the potential for relieving pain. METHODS: In an experimental model, pancreatic electrolysis was investigated. The pancreatic duct was cannulated via a transduodenal approach with an electrode catheter. In 6 animals an electrolytic "lesion" was created using a direct current generator. Six animals were controls. The local and systemic effects of electrolysis were assessed using histological and biochemical parameters. RESULTS: The pancreatic duct was cannulated in all animals and treatment was uneventful. Electrolytic lesions comprised a central area of necrosis with a sharp demarcation between necrotic and viable pancreas. All animals developed transient hyperamylasemia after electrolysis. There was no significant difference between treatment and controls. Importantly, no animal had clinical, biochemical, or histological evidence of pancreatitis. CONCLUSIONS: This experimental study suggested that electrolytic palliation of inoperable pancreatic cancer via the gastrointestinal tract is potentially safe. In patients, this treatment could be performed during endoscopic retrograde cholangiopancreatography and may have therapeutic advantages when compared to stenting or biliary bypass.

The mystery of liver regeneration.

BACKGROUND: Partial hepatectomy is the strongest stimulator of hepatic regeneration. The process of initiation and the control of the final size of the regenerated liver have been the subject of research for many years. A better understanding of this process and the effect of disease may allow better selection of patients for partial hepatectomy. It may also allow an insight into the possible application of clinical stimulation of regeneration. METHODS: Data were reviewed from the published literature using the Medline database. RESULTS: Most knowledge comes from in vitro studies and the study of resection in the rat model. A variety of cytokines, hormones and growth factors are involved in regeneration but very few have been found capable of stimulating regeneration in vitro. The exact interactions are not known, but there is probably a cascade involving different factors at differing stages of regeneration. CONCLUSION: Further in vivo research should allow greater understanding of liver regeneration, thereby providing a potential therapeutic tool in patients for whom regeneration has failed, or is likely to fail. Such research is also important in respect of liver support devices, which may inhibit liver regeneration by filtration of many of the factors involved.

Lateral laparoscopic port sites should all be closed: the incisional "spigelian" hernia.

Incisional hernias are a recognized complication of all abdominal surgery, including laparoscopic surgery. Although most cases of laparoscopic port incisional hernias are seen in the midline, particularly around the umbilicus, there are several reports of herniation at laterally placed ports. Accepted surgical practice is to close the deep fascial layers at midline laparoscopic ports. However, the deep layers at the lateral ports are not usually closed. Two near-identical cases are reported in which incisional hernias have developed at the site where laterally placed 10-mm ports have pierced the spigelian fascia. Hernia development at an iatrogenic defect in an area that is already potentially weak, and therefore prone to herniation, has implications for lateral 10-mm port site closure. The closure of the deep layers of all lateral laparoscopic ports is advocated, especially if the spigelian fascia is pierced.

A novel technique for the laparoscopic resection of mesenteric cysts.

Mesenteric cysts are rare, invariably benign intraabdominal tumors. Optimal surgical management requires complete excision of these lesions. The advent of laparoscopic surgery has allowed resection of these cysts to be achieved without full laparotomy. However, laparoscopic resection necessitates drainage of the cyst within the abdomen to facilitate extraction of the cyst through the laparoscopic ports. This article describes a novel technique in which the cyst was partially aspirated as the initial surgical maneuver. This in turn allowed traction to be applied to the cyst wall, such that it could be drawn up into the epigastric port, to aid the further dissection and removal of the cyst from the peritoneal cavity.