P755The impact of levothyroxine on cardiac function in older adults with subclinical hypothyroidism: a randomized clinical trial

Importance

Subclinical hypothyroidism has been associated with heart failure, but no conclusive clinical trial assessed whether treating subclinical hypothyroidism with levothyroxine has an impact on cardiac function.

Objective

To assess the impact of levothyroxine treatment on cardiac function in subclinical hypothyroidism.

Design

This is a randomized, double-blind placebo-controlled, multicenter Swiss substudy within the TRUST trial.

Participants

Participants aged ≥65 years with subclinical hypothyroidism.

Intervention

Levothyroxine to achieve TSH normalization, or placebo including mock titrations.

Main outcome measures

Primary outcomes, assessed by echocardiography at the end of the trial were the left ventricular ejection fraction (LVEF, normal defined as >50%) for systolic function and the ratio between mitral peak velocity of early filling (E) to early diastolic mitral annular velocity (e' (E/e' ratio) for diastolic function. Secondary outcomes included transmitral E and A waves, e' lateral/septal, left atrial (LA) volume index and systolic pulmonary artery pressure.

Results

Of 217 randomized Swiss participants of the TRUST trial, 185 (mean age 74.1 years, 47% women, mean TSH at baseline 6.35 ± SD 1.95 mIU/L) underwent echocardiography. After a median treatment duration of 18.4 months, the mean TSH among participants randomized to levothyroxine (n=95) decreased to 3.55 mIU/L, whereas it remained elevated in the placebo group (n=89; 5.29 mIU/L). The mean LVEF was similar in both arms (adjusted between-group difference 0.4%, 95% CI −1.8% to 2.5%, P=0.72) and no significant differences were found for the E/e' ratio (adjusted between-group difference 0.4, 95% CI −0.7 to 1.4, P=0.47). In intention-to-treat and per-protocol analyses, no clinically significant differences were found for secondary diastolic function parameters: e' lateral 8 vs. 8 cm/s, P=0.54; e' septal 6 vs. 6 cm/s, P=0.75; LA volume index 34 vs. 33 ml/m2, P=0.57; E/A ratio 0.8 vs. 0.8, P=0.94; E deceleration time 225 vs. 216 ms, P=0.27, except for systolic pulmonary artery pressure (37 mm Hg in the levothyoxine group vs. 33 mm Hg in the placebo group, P=0.02 intention-to-treat and P=0.06 per protocol)

Conclusion

Treatment of subclinical hypothyroidism with levothyroxine was not associated with benefits regarding systolic and diastolic heart function in older adults with subclinical hypothyroidism.

Thrombin-activatable fibrinolysis inhibitor in human abdominal aortic aneurysm disease

Essentials Patients with abdominal aortic aneurysms (AAA) develop dense clots that are resistant to lysis. This study explores the role of thrombin-activatable fibrinolysis inhibitor (TAFI) in human AAA. There is evidence of chronically increased TAFI activation in patients with AAA. TAFI may represent a pharmacological target for cardiovascular risk reduction in AAA.

SUMMARY

Background Intra-luminal thrombosis is a key factor in growth of abdominal aortic aneurysms (AAAs). Patients with AAA form dense clots that are resistant to fibrinolysis. Thrombin-activatable fibrinolysis inhibitor (TAFI) has been shown to influence AAA development in murine models. Objective The aim of this study is to characterize the role of TAFI in human AAA. Methods Plasma levels of TAFI, TAFI activation peptide (TAFI-AP), activated/inactivated TAFI (TAFIa/ai) and plasmin-α2-antiplasmin complex were measured by ELISAs in patients with AAA (n = 202) and controls (n = 188). Results TAFIa/ai and TAFI-AP levels were higher in patients than controls (median [IQR], 20.3 [14.6-32.8] ng mL-1 vs. 14.2 [11.2-19.3] ng mL-1 and 355.0 [232.4-528.1] ng mL-1 vs. 248.6 [197.1-328.1] ng mL-1 ). TAFIa/ai was positively correlated with TAFI-AP (r = 0.164). Intact TAFI levels were not different between patients and controls (13.4 [11.2-16.1] μg mL-1 vs. 12.8 [10.6-15.4] μg mL-1 ). Plasmin-α2-antiplasmin was higher in AAA patients than controls (690.0 [489.1-924.3] ng mL-1 vs. 480.7 [392.6-555.3] ng mL-1 ). Conclusions The increase in TAFIa/ai and TAFI-AP suggests an increased TAFI activation in patients with AAA. Prospective studies are required to further elucidate the role of TAFI and fibrinolysis in AAA pathogenesis.

Subclavian Stents and Stent-Grafts: Cause for Concern?

Purpose:

To report cases of stent and stent-graft fracture in the subclavian vessels.

Methods and Results:

Three patients with self-expanding stents of 3 different types in 1 subclavian artery and 2 subclavian veins presented with recurrent symptoms 6 months to 2 years after stenting. All devices showed signs of compression with stent fracture. The covered stent in the subclavian artery was excised. Of the 2 venous patients, 1 was treated with first rib resection and the other refused further treatment.

Conclusions:

The subclavian vessels are prone to flexion during movement, and the vessels may be compressed by external structures, including the clavicle and first rib. Stents that have not been designed to withstand these forces may be damaged.

Dung beetles in an avian-dominated island ecosystem: feeding and trophic ecology

Globally, dung beetles (Scarabaeidae: Scarabaeinae) are linked to many critical ecosystem processes involving the consumption and breakdown of mammal dung. Endemic New Zealand dung beetles (Canthonini) are an anomaly, occurring at high abundance and low diversity on an island archipelago historically lacking terrestrial mammals, except bats, and instead dominated by birds. Have New Zealand's dung beetles evolved to specialise on bird dung or carrion, or have they become broad generalist feeders? We test dietary preferences by analysing nitrogen isotope ratios of wild dung beetles and by performing feeding behaviour observations of captive specimens. We also use nitrogen and carbon stable isotopes to determine if the dung beetle Saphobius edwardsi will consume marine-derived carrion. Nitrogen isotope ratios indicated trophic generalism in Saphobius dung beetles and this was supported by behavioural observations where a broad range of food resources were utilised. Alternative food resource use was further illustrated experimentally by nitrogen and carbon stable isotope signatures of S. edwardsi, where individuals provided with decomposed squid had δ(15)N and δ(13)C values that had shifted toward values associated with marine diet. Our findings suggest that, in the absence of native mammal dung resources, New Zealand dung beetles have evolved a generalist diet of dung and carrion. This may include marine-derived resources, as provided by the seabird colonies present in New Zealand forests before the arrival of humans. This has probably enabled New Zealand dung beetles to persist in indigenous ecosystems despite the decline of native birds and the introduction of many mammal species.

Re: The safety of oral calcium formate

A Short Communication was published in the October 2002 issue of the New Zealand Veterinary Journal entitled An investigation of the safety of oral calcium formate in dairy cows using clinical, biochemical and histopathological parameters (McIntyre and Weston 2002). It appeared to be comparing results directly with those of a prior communication (Scott and Van Wijk 2000). The following should be considered when comparing the two papers. Haptoglobins were propounded by McIntyre and Weston as definitive indicators of acute inflammation, yet current literature does not give consistent viewpoints as to their value. The authors cited instances where the haptoglobin concentration was measured in cases of infective disease. However, Skinner et al (1991) believed that haptoglobin concentrations increase as a result of the infection rather than the trauma. To further complicate matters Alsemgeest et al (1994) found that haptoglobin concentrations were elevated in cattle with chronic rather than acute conditions whereas Horadagoda et al (1999) believed the concentrations of acute-phase proteins were higher in acute inflammation. However, they found serum amyloid A was more reliable as an indicator of acute, rather than chronic, inflammation than was haptoglobin. Therefore, histopathology would appear to give much more conclusive evidence of mucosal inflammation than the determination of haptoglobin...

Demonstration of a high-field short-period superconducting helical undulator suitable for future TeV-scale linear collider positron sources

The first demonstration of a full-scale working undulator module suitable for future TeV-scale positron-electron linear collider positron sources is presented. Generating sufficient positrons is an important challenge for these colliders, and using polarized e(+) would enhance the machine's capabilities. In an undulator-based source polarized positrons are generated in a metallic target via pair production initiated by circularly polarized photons produced in a helical undulator. We show how the undulator design is developed by considering impedance effects on the electron beam, modeling and constructing short prototypes before the successful fabrication, and testing of a final module.

Inter- and intra-laboratory study to determine the reproducibility of toxicogenomics datasets

The application of toxicogenomics as a predictive tool for chemical risk assessment has been under evaluation by the toxicology community for more than a decade. However, it predominately remains a tool for investigative research rather than for regulatory risk assessment. In this study, we assessed whether the current generation of microarray technology in combination with an in vitro experimental design was capable of generating robust, reproducible data of sufficient quality to show promise as a tool for regulatory risk assessment. To this end, we designed a prospective collaborative study to determine the level of inter- and intra-laboratory reproducibility between three independent laboratories. All test centres (TCs) adopted the same protocols for all aspects of the toxicogenomic experiment including cell culture, chemical exposure, RNA extraction, microarray data generation and analysis. As a case study, the genotoxic carcinogen benzo[a]pyrene (B[a]P) and the human hepatoma cell line HepG2 were used to generate three comparable toxicogenomic data sets. High levels of technical reproducibility were demonstrated using a widely employed gene expression microarray platform. While differences at the global transcriptome level were observed between the TCs, a common subset of B[a]P responsive genes (n=400 gene probes) was identified at all TCs which included many genes previously reported in the literature as B[a]P responsive. These data show promise that the current generation of microarray technology, in combination with a standard in vitro experimental design, can produce robust data that can be generated reproducibly in independent laboratories. Future work will need to determine whether such reproducible in vitro model(s) can be predictive for a range of toxic chemicals with different mechanisms of action and thus be considered as part of future testing regimes for regulatory risk assessment.

Acute lower limb ischemia following pediatric renal transplantation

Live donor renal transplantation remains the best treatment option for end stage renal failure in pediatric patients (1-3). Better understanding of the hemodynamics of donor-recipient size discrepancy and advances in interventional techniques with improved surgical techniques have decreased the incidence and severity of surgical complications and enhanced graft survival (1, 2). We describe a rare complication occurring intra-operatively in a pediatric renal transplant resulting in acute limb ischemia and the surgical option taken.

RepD-mediated recruitment of PcrA helicase at the Staphylococcus aureus pC221 plasmid replication origin, oriD

Plasmid encoded replication initiation (Rep) proteins recruit host helicases to plasmid replication origins. Previously, we showed that RepD recruits directionally the PcrA helicase to the pC221 oriD, remains associated with it, and increases its processivity during plasmid unwinding. Here we show that RepD forms a complex extending upstream and downstream of the core oriD. Binding of RepD causes remodelling of a region upstream from the core oriD forming a ‘landing pad’ for the PcrA. PcrA is recruited by this extended RepD–DNA complex via an interaction with RepD at this upstream site. PcrA appears to have weak affinity for this region even in the absence of RepD. Upon binding of ADPNP (non-hydrolysable analogue of ATP), by PcrA, a conformational rearrangement of the RepD–PcrA–ATP initiation complex confines it strictly within the boundaries of the core oriD. We conclude that RepD-mediated recruitment of PcrA at oriD is a three step process. First, an extended RepD–oriD complex includes a region upstream from the core oriD; second, the PcrA is recruited to this upstream region and thirdly upon ATP-binding PcrA relocates within the core oriD.

Identification of the N-linked glycosylation sites of the human relaxin receptor and effect of glycosylation on receptor function

The relaxin receptor, RXFP1, is a member of the leucine-rich repeat-containing G-protein-coupled receptor (LGR) family. These receptors are characterized by a large extracellular ectodomain containing leucine-rich repeats which contain the primary ligand binding site. RXFP1 contains six putative Asn-linked glycosylation sites in the ectodomain at positions Asn-14, Asn-105, Asn-242, Asn-250, Asn-303, and Asn-346, which are highly conserved across species. N-Linked glycosylation is the most common post-translational modification of G-protein-coupled receptors, although its role in modulating receptor function differs. We herein investigate the actual N-linked glycosylation status of RXFP1 and the functional ramifications of these post-translational modifications. Site-directed mutagenesis was utilized to generate single- or multiple-glycosylation site mutants of FLAG-tagged human RXFP1 which were then transiently expressed in HEK-293T cells. Glycosylation status was analyzed by immunoprecipitation and Western blot and receptor function analyzed with an anti-FLAG ELISA, (33)P-H2 relaxin competition binding, and cAMP activity measurement. All of the potential N-glycosylation sites of RXFP1 were utilized in HEK-293T cells, and importantly, disruption of glycosylation at individual or combinations of double and triple sites had little effect on relaxin binding. However, combinations of glycosylation sites were required for cell surface expression and cAMP signaling. In particular, N-glycosylation at Asn-303 of RXFP1 was required for optimal intracellular cAMP signaling. Hence, as is the case for other LGR family members, N-glycosylation is essential for the transport of the receptor to the cell surface. Additionally, it is likely that glycosylation is also essential for the conformational changes required for G-protein coupling and subsequent cAMP signaling.

Changes in expression of steroid receptors, their downstream target genes and their associated co-regulators during the sequential acquisition of tamoxifen resistance in vitro

Tamoxifen resistance (TAMr) in breast cancer is a serious clinical dilemma, with no satisfactory explanation. We hypothesised that changes in the expression of steroid hormone receptors (ERalpha, ERbeta), their downstream target genes (PR, pS2) and their associated co-regulators (AIB-1, SRC-1, SRA, NCoR-1, SMRT and REA) could be related to the acquisition of TAMr. To test this hypothesis, we developed in vitro TAMr cell line models by continuous exposure of MCF-7 cells to 4-hydroxytamoxifen (4-HT) over 12 (MCF-7MMU1) and 21 (MCF-7MMU2) months, respectively and examined the expression of the above by Western blotting and immunohistochemistry. In addition, we further examined the changes in global gene expression in TAMr cells in comparison with TAM-sensitive cells by microarray analysis. We report here that acquisition of TAMr is associated with changes in the expression of PR, pS2 and several co-activators, but not ERs. In addition, genes associated with cell cycle, cell adhesion and extracellular matrix, were up-regulated while those associated with apoptosis or growth factors/hormones were down-regulated. Based on our results, it appears that increased co-activator expression, in concert with alterations in genes associated with controlling cell proliferation and survival contribute to TAMr in breast cancer.

Leucine-rich repeat-containing G-protein-coupled receptor 8 in mature glomeruli of developing and adult rat kidney and inhibition by insulin-like peptide-3 of glomerular cell proliferation

Leucine-rich repeat-containing G-protein-coupled receptor 8 (LGR8, or RXFP2) is a member of the type C leucine-rich repeat-containing G protein-coupled receptor family, and its endogenous ligand is insulin-like peptide-3 (INSL3). Although LGR8 expression has been demonstrated in various human tissues, including testis, ovary, brain and kidney, the precise roles of this receptor in many of these tissues are unknown. In an effort to better understand INSL3-LGR8 systems in the rat, we cloned the full-length Lgr8 cDNA and investigated the presence and cellular localization of Lgr8 mRNA expression in adult and developing rat kidney. On the basis of these findings, we investigated the presence and distribution of renal 125I-labelled human INSL3-binding sites and the nature of INSL3-LGR8 signalling in cultured renal cells. Thus, using in situ hybridization histochemistry, cells expressing Lgr8 mRNA were observed in glomeruli of renal cortex from adult rats and were tentatively identified as mesangial cells. Quantitative, real-time PCR analysis of the developmental profile of Lgr8 mRNA expression in kidney revealed highest relative levels at late stage gestation (embryonic day 18), with a sharp decrease after birth and lowest levels in the adult. During development, silver grains associated with Lgr8 mRNA hybridization were observed overlying putative mesangial cells in mature glomeruli, with little or no signal associated with less-mature glomeruli. In adult and developing kidney, specific 125I-INSL3-binding sites were associated with glomeruli throughout the renal cortex. In primary cultures of glomerular cells, synthetic human INSL3 specifically and dose-dependently inhibited cell proliferation over a 48 h period, further suggesting the presence of functional LGR8 (receptors) on these cells (mesangial and others). These findings suggest INSL3-LGR8 signalling may be involved in the genesis and/or developmental maturation of renal glomeruli and possibly in regulating mesangial cell density in adult rat kidney.

Characterization of the Mouse and Rat Relaxin Receptors

Rodent models have been used for many years to probe the actions of relaxin. Identification of the orthologs of human leucine-rich repeat-containing g-protein-coupled receptor 7 (LGR7), the relaxin receptor, in mouse and rat will enable characterization of the response of LGR7 to relaxin in these species. Partial LGR7 homologous sequences from mouse and rat were discovered in the Celera and NCBI gene databases, amplified, cloned, and sequenced. At the protein level, mouse and rat LGR7 are 85.2% and 85.7% identical to human LGR7. Mouse and rat LGR7 were able to bind to and be activated by relaxin ligands.

Characterization of the Rat INSL3 Receptor

Human LGR8, initially discovered as a low-affinity relaxin receptor, has now been characterized as the INSL3 receptor. To investigate LGR8 function in the rat, an LGR8 ortholog was identified in the rat genome, and the full-length sequence was cloned and expressed. Rat LGR8 bound INSL3 with high affinity, clearly demonstrating that it is the rat INSL3 receptor. Interestingly, native rat relaxin did not activate rat LGR8, indicating that relaxin is not an endogenous ligand for rat LGR8. LGR8 mRNA expression was demonstrated in the gubernaculum at the time of testis descent and in the testis associated with germ cells.

LGR7-truncate is a splice variant of the relaxin receptor LGR7 and is a relaxin antagonist in vitro

The relaxin receptor (LGR7) and the insulin-like peptide 3 (INSL3) receptor (LGR8) are unique LGR family members in possessing a single, functionally important amino terminal LDL-A module.1 Mouse and rat cDNA was screened for LGR7 and LGR7 splice variant expression. A uterus-specific exon 4 deleted variant was identified and named LGR7-Truncate. Deletion of exon 4 results in a premature stop codon and a transcript that putatively encodes a secreted protein containing LGR7's LDL-A module. Expression of LGR7-Truncate with LGR7 in HEK-293T cells resulted in decreased relaxin-induced signaling of LGR7. LGR7-Truncate is potentially an endogenous regulator of LGR7 signaling.

Regulation of stromal cell cyclooxygenase-2 in the Apc Min/+ mouse model of intestinal tumorigenesis

Cyclooxygenase-2 (Cox-2) is expressed predominantly by stromal cells in intestinal adenomas from the Apc(Min/+) mouse model of familial adenomatous polyposis. We investigated the mechanistic basis of stromal cell Cox-2 expression in Apc(Min/+) mouse adenomas, as well as Cox-2 expression and activity in histologically normal (HN) Apc(Min/+) mouse intestine, in order to gain further insights into regulation of Cox-2 as a potential chemoprevention target. Upregulation of Cox-2 in intestinal tumours is not an intrinsic feature of Apc(Min/+) macrophages as bone marrow-derived Apc(Min/+) macrophages did not exhibit an abnormality in Cox-2 expression or activity. Intestinal permeability to lactulose or mannitol was similar in Apc(Min/+) mice and wild-type littermates, implying that macrophage activation by luminal antigen is unlikely to explain stromal cell Cox-2 induction. Moreover, stromal cells exhibited differential expression of Cox-2 and inducible nitric oxide synthase, suggesting 'alternative' (M2) rather than 'classical' (M1) macrophage activation. Flow cytometric sorting of isolated stromal mononuclear cells (SMNCs), on the basis of M-lysozyme and specific macrophage marker expression, demonstrated that macrophages, neutrophils and non-myelomonocytic cells all contributed to lamina propria prostaglandin (PG) E(2) synthesis. However, the majority of PGE(2) synthesis by macrophages was via a Cox-2-dependent pathway compared with predominant Cox-1-derived PGE(2) production by non-myelomonocytic cells. SMNCs from HN Apc(Min/+) intestinal mucosa exhibited similar levels of Cox-2 mRNA and protein, but produced more Cox-2-derived PGE(2) than wild-type cells at 70 days of age. There was an age-dependent decline in PGE(2) synthesis by Apc(Min/+) SMNCs, despite tumour progression. These data suggest that other Cox-2-independent factors also control PGE(2) levels during Apc(Min/+) mouse intestinal tumorigenesis. Regulation of macrophage Cox-2 expression and other steps in PGE(2) synthesis (e.g. PGE synthase) are valid targets for novel chemoprevention strategies that could minimize or avoid systemic COX-2 inhibition.

Comparison in dairy cattle of mucosal toxicity of calcium formate and calcium chloride in oil

AIM

Oral aqueous preparations of calcium chloride have been well established as causes of gastro-intestinal irritation in cattle. Recently another calcium salt, calcium formate, has been marketed as a treatment and prevention for hypocalcaemia, with the claim that it is non-irritant. The aim of this trial was to establish the safety of calcium formate in the target animal.

METHODS

Nine Friesian milking cows were selected and separated at random into three groups. Three were treated with calcium formate, three with calcium chloride in soya bean oil as a positive control and three were negative controls. Cows were slaughtered 6 hours after the last administration and the rumen, reticulum, omasum and abomasum examined by an operator who was unaware of the experimental status of the animals.

RESULTS

There was diffuse reddening and swelling of the abomasal mucosa in two of the three cows treated with calcium formate but no lesions in those treated with calcium chloride in soya bean oil or in the negative controls. Histology of the affected portions of abomasum showed areas of necrosis of the mucosa and some acute inflammation. The submucosa was also haemorrhagic with moderate numbers of polymorphonuclear neutrophils present. Histology on other animals was unremarkable.

CONCLUSION

Calcium formate may not be a safe oral treatment for cattle. Further testing is required.

CLINICAL RELEVANCE

Calcium formate, in the high concentrations required for therapy of hypocalcaemia may not be a safe treatment.

Identification and characterization of the mouse and rat relaxin receptors as the novel orthologues of human leucine-rich repeat-containing G-protein-coupled receptor 7

1. Relaxin is an extracellular matrix (ECM)-remodelling hormone that is functionally important in reproductive tissues, brain, lung and heart. 2. Recently, the human relaxin receptor was identified as leucine-rich repeat-containing G-protein-coupled receptor 7 (LGR7). 3. Using human LGR7 as a template, we identified mouse and rat LGR7 orthologues in the Celera and National Centre for Biotechnology Information databases. 4. At the protein level, mouse and rat LGR7 share 85.2 and 85.7% identity with human LGR7, respectively. 5. Mouse LGR7 mRNA was detected in all tissues where relaxin binding is observed. 6. Mouse and rat LGR7 bound [33P]-relaxin with high affinity and, upon relaxin treatment, both receptors stimulated cAMP production in transfected HEK 293T cells. 7. These results indicate that mouse and rat LGR7 are the relaxin receptors in these species. 8. The actions of relaxin in rodents are well characterized, providing an established platform for research into the molecular pharmacology of the highly conserved relaxin receptor.

Development and transferability of a cost-effective laparoscopic camera navigation simulator

BACKGROUND

Laparoscopic camera navigation (LCN) is vital for the successful performance of laparoscopic operations, yet little time is spent on training. This study aimed to develop an inexpensive LCN simulator, to design a structured curriculum, and to determine the transferability of skills acquired.

METHODS

In this study, 0 degrees and 30 degrees LCN simulators were developed for use on a videotrainer platform. Transferability was tested by enrolling 20 medical students in an institutional review board-approved, randomized, controlled, blinded protocol. Subjects viewed a video tutorial and were pretested in LCN on a porcine Nissen model. Procedures were videotaped and the LCN performance was scored by a blinded rater according to the number of standardized verbal cues required and the percentage of time an optimal surgical view (%OSV) was obtained. Procedure time also was recorded. Subjects were stratified and randomized. The trained group practiced on the LCN simulator until competency was demonstrated. The control group received no training. Both groups were posttested on the porcine Nissen model.

RESULTS

The constructed simulators required 35 man hours for development, cost $25 per board for materials, and proved to be durable. The trained group demonstrated significant improvement in verbal cues (p = 0.001), %OSV (p < 0.001), and procedure time (p = 0.001), whereas the control group showed improvement only in verbal cues (p < 0.02). At posttesting, the training group demonstrated significantly better scores for verbal cues (2.1 vs 8.0; p = 0.02) and %OSV (64% vs 45% p = 0.01) than the control group.

CONCLUSION

These data suggest that the LCN simulator is cost effective and provides trainees with skills that translate to the operating room.

Incidental paraduodenal hernia found during laparoscopic colectomy

This paper describes a rare right paraduodenal hernia discovered during an elective laparoscopic colon resection. Our patient was a 60-year-old Asian man with a history of multiple bouts of diverticulitis and a lifelong history of mild constipation and postprandial abdominal pain. Prior CT scans and preoperative barium enema confirmed the diagnosis of diverticular disease, and no other abnormalities were appreciated. At laparoscopic exploration, a right paraduodenal hernia was found with complete herniation of the small intestine under the ascending colon and hepatic flexure. The unclear anatomy prompted conversion to an open laparotomy. This allowed safe reduction of the hernia and sac excision. Adhesions were lysed to relieve a partial duodenal obstruction, and a Ladd's procedure was performed to correct the incomplete rotation. Additionally, a sigmoid colectomy was performed. After prolonged ileus, the patient was discharged on postoperative day 14. At 6-month follow-up, the patient was asymptomatic and doing well.

Intraoperative ultrasound and prophylactic ursodiol for gallstone prevention following laparoscopic gastric bypass

BACKGROUND

Previous studies have shown that ursodiol decreases gallstone formation from 32% to 2% following open gastric bypass, but no data exist on laparoscopic Roux-en-Y gastric bypass (LRYGB) using intraoperative ultrasound (IOUS) screening.

METHODS

LRYGB with IOUS were performed on 195 consecutive patients. Patients with gallstones underwent simultaneous cholecystectomy, and patients without gallstones were prescribed ursodiol, 300 mg twice daily, for 6 month. Follow-up survey and ultrasound.

RESULTS

Of 195 patients, 44 (23%) had had a prior cholecystectomy, 21 (11%) underwent a simultaneous cholecystectomy, 129 (66%) had gallbladders left intact, and one (0.5%) false negative IOUS was excluded. Of 69 patients with ultrasound and survey follow-up (mean, 10 months), 19 (28%) developed gallstones seven with symptoms), and 50 (72%) were gallstone free. Forty-one percent of patients were compliant with ursodiol. There was no difference in compliance between patients with and without gallstones. In patients with gallstones, all of the symptomatic patients were noncompliant, whereas none of the compliant patients developed symptoms. Medication side-effects occurred in 17 of 69 patients (25%).

CONCLUSIONS

IOUS during LRYGB efficiently screens for gallstones, and selective cholecystectomy followed by prophylactic ursodiol results in low morbidity. Improvements in compliance may lower the incidence of postoperative gallstone formation.

Surgeon workload and motion efficiency with robot and human laparoscopic camera control

BACKGROUND

Surgeons are now being assisted by robotic systems in a wide range of laparoscopic procedures. Some reports have suggested that robot-assisted camera control (RACC) may be superior to a human driver in terms of quality of view and directional precision, as well as long-term cost savings. Therefore, we setout to investigate the impact of RACC of surgeon motion efficiency.

METHODS

Twenty pigs were randomized to undergo a standardized laparoscopic Nissen fundoplication with either a human or RACC system, the AESOP 2000. All procedures were performed by the same surgical fellow. Time was recorded for dissection and suture phases. Inertial motion sensors were used to monitor both the surgeon's hands and the camera. Digitized data were analyzed to produce summary measures related to overall motion.

RESULTS

The operative times were slightly longer with RACC (mean 80.2 +/- 20.6 vs 73.1 +/- 15.4 min, not significant). With regard to operative times and surgeon motion measures, the only statistically significant differences were for setup and breakdown times, which contributed <15% to the total time for the procedure.

CONCLUSION

In terms of impact on surgeon motion efficiency and operative time under normal surgical conditions, RACC is essentially the same as an expert human driver. However, careful planning and structuring of the surgical suite may yield some small gains in operative time.

The effect of hepatic inflow occlusion on laparoscopic radiofrequency ablation using simulated tumors

BACKGROUND

The purpose of this study was to determine the effect of hepatic inflow occlusion (the Pringle maneuver) on laparoscopic radiofrequency (RF) ablation.

METHODS

Using a previously validated agarose tissue-mimic model, 1-cm simulated hepatic tumors (three per animal) were laparoscopically ablated in five pigs with normal perfusion and then in five pigs with hepatic artery and portal vein occlusion. Energy was applied until tissue temperature reached 100 degrees C (warm-up) and thereafter for eight min. Specimens were examined immediately after treatment.

RESULTS

Vascular occlusion was successful in all cases per color-flow Doppler ultrasound. Pringle time was 11.4 +/- 1.6 min. Warm-up time (2.7 +/- 1.4 vs 20.2 +/- 14.0 min) was significantly faster in the Pringle group. Ablation diameter (34.8 +/- 2.9 vs 24.7 +/- 3.1 mm), proportion of round/ovoid lesions (93% vs 20%), ablation symmetry (100% vs 40%), and margin distance (5.1 +/- 3.0 vs 1.1 +/- 1.2 mm) were significantly better for the Pringle group than the No Pringle group, respectively.

CONCLUSION

Using a Pringle maneuver during laparoscopic RF ablation significantly enhances ablation geometry and results in larger margins.

Comparison of video trainer and virtual reality training systems on acquisition of laparoscopic skills

Training on a video trainer or computer-based minimally invasive surgery trainer leads to improved benchtop laparoscopic skill. Recently, improved operative performance from practice on a video trainer was reported. The purpose of this study was three fold: (a) to compare psychomotor skill improvement after training on a virtual reality (VR) system with that after training on a video-trainer, (VT) (b) to evaluate whether skills learned on the one training system are transferable to the other, and (c) to evaluate whether VR or VT training improves operative performance. For the study, 50 junior surgery residents completed baseline skill testing on both the VR and VT systems. These subjects then were randomized to either a VR or VT structured training group. After practice, the subjects were tested again on their VR and VT skills. To assess the effect of practice on operative performance, all second-year residents (n = 19) were evaluated on their operative performance during a laparoscopic cholecystectomy before and after skill training. Data are expressed as percentage of improvement in mean score/time. Analysis was performed by Student's paired t-test. The VR training group showed improvement of 54% on the VR posttest, as compared with 55% improvement by the VT group. The VR training group improved more on the VT posttest tasks (36%) than the VT training group improved on the VR posttest tasks (17%) (p <0.05). Operative performance improved only in the VR training group (p <0.05). Psychomotor skills improve after training on both VR and VT, and skills may be transferable. Furthermore, training on a minimally invasive surgery trainer, virtual reality system may improve operative performance during laparoscopic cholecystectomy.

Rubber molecular weight regulation, in vitro, in plant species that produce high and low molecular weights in vivo

In three rubber-producing species, in vitro, the rates of initiation and polymerization and the biopolymer molecular weight produced were affected by the concentration of farnesyl diphosphate (FPP) initiator and isopentenyl diphosphate (IPP) elongation substrate (monomer). Ficus elastica, a low molecular weight-producer in vivo, synthesized rubber polymers approximately twice the molecular weight of those made by Hevea brasiliensis or Parthenium argentatum (which produce high molecular weights in vivo), possibly due to its lower IPP Km. In all species, increasing FPP concentrations increased rubber biosynthetic rate and new molecules initiated but decreased molecular weight by competition with the allylic diphosphate (APP) end of elongating rubber molecules for the APP binding site. Increasing IPP concentrations increased rubber biosynthetic rate and rubber molecular weight, but only when FPP concentrations were below the FPP Km's or where negative cooperativity operated. In conclusion, rubber transferase is not the prime regulator of rubber molecular weight in vivo.

A new device for the measurement of disease severity in patients with intermittent claudication

OBJECTIVES

To assess a new method of determining functional impairment in patients with intermittent claudication, the Double Physiological Walking Test (DPWT) using the PADHOC (Peripheral Arterial Disease Holter Control) device, against a standard treadmill test.

DESIGN

Patients with intermittent claudication presenting to the department were considered for both the DPWT and a standard treadmill test.

METHODS

initial claudicating distance, maximal walking distance and speed of walking were determined for both parts of the DPWT. Initial claudicating distance and maximal walking distance were determined from the treadmill test. Comparisons were made between the treadmill test and the DPWT.

RESULTS

The treadmill test was unable to be performed in 22% of patients due to defined contraindications. There were strong correlations in both walking distances and disease severity when comparing the DPWT and the treadmill test. Patients in whom the treadmill test was contraindicated had significantly shorter walking distances on the DPWT than those who were able to complete a treadmill walking test.

CONCLUSIONS

The DPWT correlates strongly with walking distances obtained from a standard treadmill test. However, the PADHOC can be used in a number of differing locations and settings as well as in patients in whom a treadmill test is contraindicated. It therefore has a role to play in the initial assessment of patients presenting with intermittent claudication.

Role of the neutrophil in the development of systemic inflammatory response syndrome and sepsis following abdominal aortic surgery

INTRODUCTION

There is evidence to suggest that the polymorphonuclear neutrophil (PMN) plays a critical early step in the development of the ischaemia-reperfusion syndrome, the systemic inflammatory response syndrome (SIRS) and sepsis. The PMN receptor CD16 plays an important role in phagocytosis, cell-mediated cytotoxicity and the release of free radicals and proteolytic enzymes. The aim of this study was to determine whether there is any relationship between PMN CD16 expression, phagocytosis and the development of sepsis.

METHODS

Fifty patients who underwent elective infrarenal abdominal aortic aneurysm repair were studied. Venous blood was taken before operation, throughout surgery and for 7 days after operation. CD16 expression was measured, unstimulated and following further stimulation, by means of flow cytometry. Phagocytosis was determined using flow cytometry.

RESULTS

Some 36 patients had an uncomplicated recovery; 14 developed SIRS or sepsis. There was no difference between the two groups with respect to nutritional, co-morbid or technical factors. In the group that developed septic complications after operation, the level of PMN CD16 expression was significantly higher before surgery (mean channel fluorescence (MCF) 30.2 versus 10.4; P < 0.05, Mann-Whitney U test) and throughout the postoperative period. Surgery produced no change in CD16 expression. After operation, stimulation of PMNs in the septic group resulted in a fall in CD16 expression (40.8 versus 20.4 MCF; P < 0.05, Mann-Whitney U test); surgery produced no change in the level of expression in the uncomplicated group.

CONCLUSION

This study provides evidence of phenotypic and functional differences in neutrophil behaviour in patients who develop sepsis following aneurysm surgery.

The use of impedance index in the surveillance of PTFE femorodistal grafts

BACKGROUND

Impedance is the equivalent in pulsatile flow of resistance in steady flow. The impedance index has been used successfully in the surveillance of vein grafts, but its use has not been reported in the context of PTFE femorodistal grafts.

METHODS

Twenty-eight patients (median age 68 years (IQR 59-73 years) and 20 men) undergoing 28 PTFE femorodistal grafts with a vein cuff were evaluated prospectively comparing the impedance index with standard duplex graft surveillance. All grafts were performed for critical ischaemia. At risk grafts were identified and treated appropriately after angiography.

RESULTS

The primary patencies at 1 and 2 years were 82% and 50% respectively. Duplex identified 11 at risk grafts of which 9 had an identifiable correctable lesion. Impedance analysis overpredicted at risk status when compared with duplex in the immediate postoperative phase and was unsuccessful in detecting inflow disease or low flow relating to cardiac failure. Using a threshold index of 0.5, impedance analysis has a sensitivity of 87%, specificity of 88%, with positive and negative predictive values of 76% and 94% respectively.

CONCLUSIONS

Impedance index is a non-invasive method of graft surveillance which is applicable to PTFE femorodistal bypasses and may be a useful alternative to duplex although formal validation studies will be required.

Improving operative performance using a laparoscopic hernia simulator

BACKGROUND

Traditionally, the acquisition of surgical skill has occurred entirely in the operating room. To meet the expanding challenges of cost containment and patient safety, novel methods of surgical training utilizing ex-vivo workstations are being developed. The purpose of our study was to evaluate the impact of a laparoscopic training curriculum on surgical residents' operative performance.

METHODS

Twenty-one surgery residents completed baseline laparoscopic total extraperitoneal (TEP) hernia repairs. Operative performance was evaluated using a validated global assessment tool. Each resident was then randomized to a control group or a trained group. A CD ROM, video, and simulator were used for training. At the end of the study, each resident's operative performance was again evaluated.

RESULTS

Improvement was significantly greater in the trained group in five of the eight individual global assessment areas as well as the composite score (P <0.05). Questionnaire data suggested that training resulted in improved understanding of the TEP hernia repair (P = 0.01) and an increased willingness to offer the operation to patients with nonrecurrent unilateral hernias (P = 0.02).

CONCLUSIONS

A multimodality laparoscopic TEP hernia curriculum improves residents' knowledge of the TEP hernia repair and comfort in performing the procedure, and may also improve actual operative performance.

Use of insulin pumps in pregnancies complicated by type 2 diabetes and gestational diabetes in a multiethnic community

OBJECTIVE

To describe the use of insulin pump therapy in women with gestational diabetes mellitus (GDM) or type 2 diabetes in pregnancy and persistent hyperglycemia despite multiple injections of subcutaneous insulin.

RESEARCH DESIGN AND METHODS

As part of a service audit, deliveries to women with diabetes at a single South Auckland hospital were reviewed from 1991 through 1994. Glycemic control was estimated by the mean of self-recorded and laboratory postprandial glucose concentrations. In a nested case-control study, pregnancies complicated by GDM/type 2 diabetes with use of an insulin pump were compared with those without insulin pump therapy and peak insulin requirements of 100-199 units/ day, matched for ethnicity and type of diabetes.

RESULTS

A total of 30 of 251 Polynesian, European, and South Asian women with singleton pregnancies complicated by insulin-requiring GDM/type 2 diabetes used an insulin pump. An additional two women with high insulin requirements discontinued pump therapy. None of the women with GDM/type 2 diabetes experienced severe hypoglycemia, whereas 79% of the women had improved glycemic control within 1-4 weeks. Mothers using a pump had greater insulin requirements (median maximum 246 vs. 130 units per day) and greater weight gain (10.6 vs. 5.0 kg). Their babies were more likely to be admitted to the Special Care Baby Unit but were neither significantly heavier nor experienced greater hypoglycemia than control subjects.

CONCLUSIONS

Insulin pump therapy seems to be safe and effective for maintaining glycemic control in pregnancies complicated by GDM/type 2 diabetes and requiring large doses of insulin.

The impact of intense laparoscopic skills training on the operative performance of urology residents

PURPOSE

As laparoscopy has become more commonplace in urology, increased emphasis has been placed on laparoscopic education. We assessed the impact of laparoscopic skills training on the operative performance of urological surgeons inexperienced with laparoscopy.

MATERIALS AND METHODS

Urology residents were prospectively randomized to undergo laparoscopic skills training (6) or no training (6). Baseline assessment of operative performance (scale 0 to 35) during porcine laparoscopic nephrectomy was completed by all subjects. Cumulative time to complete laparoscopic tasks using an inanimate trainer was also recorded. The skills training group then practiced inanimate trainer tasks for 30 minutes daily for 10 days. The 2 groups then repeated the timed inanimate trainer tasks and underwent repeat assessment of the ability to perform porcine laparoscopic nephrectomy.

RESULTS

At baseline no statistical difference was noted in laparoscopic experience, inanimate trainer time or overall operative assessment in the 2 groups. In the skills training group mean cumulative time to complete inanimate trainer tasks decreased from 341 to 176 seconds (p = 0.003), while in the control group it decreased from 365 to 301 (p = 0.15). Operative assessment improved from initial to repeat porcine laparoscopic nephrectomy regardless of the trained versus control randomization grouping (22.0 to 27.8, p = 0.0008 and 20.8 to 26.5, p = 0.00007, respectively).

CONCLUSIONS

In vivo experience enables urological surgeons inexperienced with laparoscopy to improve significantly in all aspects of complex laparoscopic procedures. In this pilot study the magnitude of improvement was independent of additional training in laparoscopic skills. Educational curriculum should include in vivo practice in addition to skills training.

Lack of inducible nitric oxide synthase promotes intestinal tumorigenesis in the Apc(Min/+) mouse

BACKGROUND & AIMS

The role of the inducible isoform of nitric oxide synthase (Nos2 or iNOS) in intestinal tumorigenesis is unclear. Conflicting data also exist regarding the ability of Nos2 to modulate expression and/or activity of cyclooxygenase 2 (Cox-2), which promotes intestinal tumorigenesis. Therefore, we determined the effect of a null Nos2 genotype on intestinal tumorigenesis and Cox-2 expression/activity in the Apc(Min/+) mouse model of familial adenomatous polyposis.

METHODS

Apc(Min/+)Nos2(-/-) mice were generated by successive crosses between C57BL/6-Apc(Min/+) and C57BL/6-Nos2(tm1Lau) mice. Adenoma characteristics of age-matched Apc(Min/+)Nos2(+/+) and Apc(Min/+)Nos2(-/-) mice were compared. The level and cellular localization of Nos2 messenger RNA (mRNA) expression in Apc(Min/+)Nos2(+/+) mouse intestine was determined. Cox-2 expression and activity were measured in both intestinal tissue and bone marrow-derived macrophages in vitro.

RESULTS

Apc(Min/+)Nos2(-/-) mice developed significantly more intestinal adenomas than Apc(Min/+)Nos2(+/+) littermates. Epithelial cell Nos2 mRNA expression was decreased in adenomas compared with histologically normal Apc(Min/+)Nos2(+/+) intestine. There was no significant difference in Cox-2 expression or activity in either intestine or bone marrow-derived macrophages from Apc(Min/+)Nos2(+/+) and Apc(Min/+)Nos2(-/-) animals.

CONCLUSIONS

Nos2 plays an antineoplastic role in the Apc(Min/+) mouse model of familial adenomatous polyposis. Nos2 does not modulate Cox-2 expression or activity in the Apc(Min/+) mouse.

The use of a standard proforma in breast cancer reporting

AIM

To determine whether the introduction of a standard reporting proforma has led to an improvement in the completeness of histopathology reports for breast cancer excision specimens.

METHODS

A standard reporting proforma was designed using the Royal College of Pathologists' minimum dataset for breast cancer histopathology reports and the national histopathology reporting form of the National Health Service (NHS) breast screening programme. This was introduced into our department in June 1999, with reports generated from the proforma replacing the standard text reports. The pathological information contained in 50 text reports issued before the introduction of the proforma and 50 reports generated using the proforma was compared with the minimum dataset and NHS breast screening programme guidelines.

RESULTS

A general improvement in documentation of individual pathological features was noted after introduction of the proforma. This was most significant in relation to documentation of features, such as microcalcification and ductal carcinoma in situ. In addition, important features such as tumour grade, tumour size, and hormone receptor status were documented more frequently in the proforma group. There was an overall increase in the number of reports regarded as complete after introduction of the proforma.

CONCLUSIONS

The introduction of a standard proforma led to a significant improvement in the completeness of breast cancer histopathology reports in this centre, but continued vigilance is needed to ensure that standards continue to improve.

Simplifying the internal iliac artery aneurysm

Isolated aneurysms of the internal iliac (hypogastric) artery are a rare variant of aorto-iliac aneurysm disease, with an incidence at around 0.04% of all aorto-iliac aneurysms. Because of their location deep within the pelvis, they may present late and are often large. The incidence of rupture is high and may be up to 38% at initial presentation; furthermore, this has been reported to carry a 58% mortality rate. As such the early and aggressive management of isolated internal iliac artery aneurysms (IIAAs) is mandatory to avoid the high morbidity and mortality associated with rupture. This article includes a literature review regarding IIAAs and outlines the current surgical and endovascular management options for this most rare and technically challenging of aneurysms.

Laparoscopic Roux-en-Y gastric bypass using the porcine model

BACKGROUND

The laparoscopic Roux-en-Y gastric bypass (LRYGBP) may be performed using a variety of methods. The purpose of this study was to learn how to perform the Roux-en-Y gastric bypass operation laparoscopically, using a porcine model.

MATERIALS AND METHODS

11 domestic pigs (mean weight 47 kg) underwent LRYGBP. In 8 animals, a completely laparoscopic approach was attempted, while in 3 animals a hand-assist device was used. Techniques for anvil placement, pouch calibration, and limb-length measurement were evaluated. Animals were sacrificed at the end of the procedure, and operative results were recorded.

RESULTS

The hand-assist device restored tactile feedback but obscured visualization. The gastrojejunostomy leak rate was 64%, and the jejunojejunostomy leak rate was 73%. Anvil placement using transgastric and transoral methods was feasible. Calibrating the pouch with a Baker's tube was more accurate than using anatomical landmarks. Measuring limb-lengths using Babcock clamps was reliable with practice.

CONCLUSION

The frailty of the porcine small intestine may limit one's ability to achieve intact anastomoses. Despite the anatomic limitations, the porcine model was well-suited for skill development and evaluation of techniques for performing the LRYGBP operation.

Laparoscopic skills training

BACKGROUND

The purpose of this study was to quantify the learning curve of a previously validated laparoscopic skills curriculum.

METHODS

Second-year medical students (MS2, n = 11) and second (PGY2, n = 11) and third (PGY3, n = 6) year surgery residents were enrolled into a curriculum using five video-trainer tasks. All subjects underwent baseline testing, training (30 minutes per day for 10 days), and final testing. Scores were based on completion time. The relationship between task completion time and the number of practice repetitions was examined. Improvement (the difference in baseline and final performance) amongst groups was compared by one-way analysis of variance using the baseline score as a covariate; P <0.05 indicated significance.

RESULTS

Baseline scores were not significantly different. Final scores were significantly better for MS2s versus PGY3s. Adjusted-improvement was significantly larger for the MS2s compared with PGY2s and PGY3s, and for PGY2s compared with PGY3s. The mean number of repetitions corresponding to a predicted 90th percentile score was 32.

CONCLUSION

Inexperienced subjects benefit the most from skills training. For maximal benefit, we recommend that each task be practiced for at least 30 to 35 repetitions.