Simulation and surgical training

The aim of this review was to outline current forms of surgical simulation and methods of assessing technical skills using these forms of simulation. To review this subject, a literature search was done using key words 'assessment', 'simulation', 'surgery', 'technical skills' and 'virtual reality'. Simulation in surgery has several forms, inorganic (synthetic & computer) and organic (animal or cadaver). Surgical simulation is a mode of training which is promising and may be effective. Technical errors in the simulated environment do not have clinical consequences and does not have a morbidity or mortality. We must ensure that the competent skills learnt in the simulation environment are translated to the real environment. This can be achieved if the same assessment tools are used in both environments. Surgical training is entering a new era, with increased scrutiny and an evolving work and training environment. We as surgical teachers must ensure that the surgeons of the future are as competent as or better than their predecessors using these new modes of training which we have access to.

Prevalence and numbers of Campylobacter on broiler carcasses collected at rehang and postchill in 20 U.S. processing plants

Campylobacter is a human pathogen associated with chicken and chicken meat products. This study was designed to examine the prevalence and number of Campylobacter on broiler chicken carcasses in commercial processing plants in the United States. Carcass samples were collected from each of 20 U.S. plants four times, roughly approximating the four seasons of 2005. At each plant on each sample day, 10 carcasses were collected at rehang (prior to evisceration), and 10 carcasses from the same flock were collected postchill. A total of 800 carcasses were collected at rehang and another 800 were collected postchill. All carcasses were subjected to a whole-carcass rinse, and the rinse diluent was cultured for Campylobacter. The overall mean number of Campylobacter detected on carcasses at rehang was 2.66 log CFU per ml of carcass rinse. In each plant, the Campylobacter numbers were significantly reduced by broiler processing; the mean concentration after chill was 0.43 log CFU/ml. Overall prevalence was also reduced by processing from a mean of > or =30 of 40 carcasses at rehang to > or =14 of 40 carcasses at postchill. Seven different on-line reprocessing techniques were applied in the test plants, and all techniques resulted in <1 log CFU/ml after chilling. Use of a chlorinated carcass wash before evisceration did not affect the postchill Campylobacter numbers. However, use of chlorine in the chill tank was related to lower numbers on postchill carcasses. Overall, U.S. commercial poultry slaughter operations are successful in significantly lowering the prevalence and number of Campylobacter on broiler carcasses during processing.

Endogenous knock-down of survival genes improves chemotherapeutic response in a T-ALL cell line

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Background: New targets for more effective, less toxic therapeutic approaches to childhood acute lymphoblastic leukemia (ALL) can be developed by discovering pathways unique to the blast. Using microarray technology, we identified potential target genes that are up-regulated at relapse compared to diagnosis (Blood 2006;108:711–7). Two genes, survivin and securin, were selected for analysis because they are involved in cell cycle regulation, apoptosis and cellular transformation. We hypothesized that decreasing endogenous expression of these genes would increase apoptosis and sensitize cells to chemotherapy. Methods: Short hairpin RNA constructs (shRNA) targeting both transcripts and a control shRNA were engineered. LSN2181295 (sodium salt of LY2181308), an antisense molecule targeting survivin developed by Eli Lilly and its mismatch control (LSN2293329) were also tested. The T- ALL cell line Molt4 was transiently transfected with shRNA constructs or antisense oligos. Western blot and qRT-PCR were performed to determine the time course of target knock-down while apoptosis was assessed by annexin-V labeling. Following transfection, cells were also treated with varying doses of etoposide and doxorubicin for 24 hrs prior to FACS analysis. Results: The survivin and securin shRNAs blocked endogenous gene expression by 80–90%, with maximal effect achieved at 48 hrs. Transfection of Molt4 cells with survivin and securin shRNAs induced ∼13% and 35% apoptosis, respectively, as compared to a control shRNA. When used in combination with chemotherapeutic agents, the shRNA constructs potentiated the effect of both doxorubicin and etoposide at low dosages (≤100 nM and ≤0.4 uM respectively, p values <0.01). The antisense survivin drug had a similar effect as the survivin shRNA and also potentiated the effect of vincristine. Conclusion: Targeting levels of survivin and securin in conjunction with standard chemotherapy maximizes leukemia cell kill and effectively lowers the amount of chemotherapy needed to achieve cell death. Such an approach may improve overall survival for patients at relapse and could also lead to the delivery of effective chemotherapy at less toxic doses.

No significant financial relationships to disclose.

Distribution of Clostridium difficile PCR ribotype 027 in British hospitals

An outbreak of Clostridium difficile infection in Stoke Mandeville hospital in south-east England [1] in 2004/2005 was primarily due to a new and possibly more virulent strain known in the United Kingdom (UK) as PCR ribotype 027. Coinciding with this outbreak, a surveillance programme of C. difficile isolates from symptomatic patients in England with additional results of outbreak investigation requests to the Anaerobe Reference Laboratory (ARL) in Cardiff has established the true extent of its spread throughout British hospitals.

Nevirapine versus efavirenz based antiretroviral treatment in naive Indian patients: comparison of effectiveness in clinical cohort

OBJECTIVE

Our objective was to compare immunologic effectiveness of nevirapine and efavirenz based antiretroviral therapy in antiretroviral naïve HIV-1 infected Indian patients.

DESIGN AND METHODS

Study was an observational, non-randomized, longitudinal cohort. Antiretroviral naive HIV-1 infected patients receiving efavirenz + 2NRTI (n=254) and nevirapine + 2 NRTI (n=857) from April 2000 were followed up at two tertiary care HIV clinics at Ahmedabad and Pune. Patients were followed up clinically monthly and CD4 was carried out every 3 monthly. All patients were examined for various side effects as well as development of various OIs. Data were analyzed using standard statistical methods.

RESULTS

Baseline characteristics for both the groups (NVP and EFV) were comparable. In the random effects model, there was an increase of 40.97 (p < 0.05) units of CD4 cell counts with an unit increase in time in the NVP arm as against a 44.75 (p < 0.05) units of increase in CD4 cell counts in the EFV group with a unit increase in time, which is significant for both groups. However, at any given point of time there was no difference in the rate of increase of CD4 count between the two treatment arms (p = 0.58). Hypersensitivity reaction (6.6% in NVP vs. 2.32% in EFV, p = 0.0146) and hepatitis (3.2% in NVP vs. 0% in EFV, p = 0.0085) were more common with nevirapine, while neurologic disturbances (0.93% in NVP vs. 20.15% in EFV, p = 0.0001) were more common with efavirenz. Incidence of distal sensory neuropathy and lipid abnormalities was similar in both the groups.

CONCLUSION

Use of NVP and EFV based HAART in antiretroviral naive Indian patients led to significant and durable rise in CD4 cell count. Although observational and non-randomized, our study showed equivalent immunological response amongst NVP and EFV based HAART which is in line with the results of the 2NN study.

Platelet nitric oxide synthase is activated by tyrosine dephosphorylation: possible role for SHP-1 phosphatase

BACKGROUND

Endothelial nitric oxide synthase (eNOS) activity in endothelial cells is regulated by post-translational phosphorylation of critical serine, threonine and tyrosine residues in response to a variety of stimuli. However, the post-translational regulation of eNOS in platelets is poorly defined.

OBJECTIVES

We investigated the role of tyrosine phosphorylation in the regulation of platelet eNOS activity.

METHODS

Tyrosine phosphorylation of eNOS and interaction with the tyrosine phosphatase SHP-1 were investigated by coimmunoprecipitation and immunoblotting. An in vitro immunoassay was used to determine eNOS activity together with the contribution of protein tyrosine phosphorylation.

RESULTS

We found platelet eNOS was tyrosine phosphorylated under basal conditions. Thrombin induced a dose- and time-dependent increase in eNOS activity without altering overall level of tyrosine phosphorylation, although we did observe evidence of minor tyrosine dephosphorylation. In vitro tyrosine dephosphorylation of platelet eNOS using a recombinant protein tyrosine phosphatase enhanced thrombin-induced activity compared to thrombin alone, but had no effect on endothelial eNOS activity either at basal or after stimulation with bradykinin. Having shown that dephosphorylation could modulate platelet eNOS activity we examined the role of potential protein phosphatases important for platelet eNOS activity. We found SHP-1 protein tyrosine phosphatase, co-associated with platelet eNOS in resting platelets, but does not associate with eNOS in endothelial cells. Stimulation of platelets with thrombin increased SHP-1 association with eNOS, while inhibition of SHP-1 abolished the ability of thrombin to induce elevated eNOS activity.

CONCLUSIONS

Our data suggest a novel role for tyrosine dephosphorylation in platelet eNOS activation, which may be mediated by SHP-1.

Frequency response adaptation of PI controllers based on recursive least-squares process identification

The frequency domain approach to adaptive control or autotuning of proportional plus integral (PI) controllers is considered in this paper. The frequency response of the process is computed from an overparametrized recursive least-squares (RLS) model and used at sample intervals to tune the PI. By simulations it is shown that the frequency response estimates converge more quickly and are more constant in the presence of disturbances than the RLS coefficients from which they are calculated. The frequency response estimates are therefore more reliable for controller tuning. The method can handle concurrent gain variation of 50% and time constant or delay variations of 100%. The method is implemented and experimentally verified on a pilot distillation column.

Inequalities in hospital admission rates for unintentional poisoning in young children

OBJECTIVE

To determine the relationship between deprivation and hospital admission rates for unintentional poisoning, by poisoning agent in children aged 0-4 years.

DESIGN

Cross sectional study of routinely collected hospital admissions data.

SETTING

East Midlands, UK.

PARTICIPANTS

1469 admissions due to unintentional poisoning over two years.

MAIN OUTCOME MEASURE

Hospital admission rates for unintentional poisoning. Incidence rate ratios (IRRs) comparing hospital admission rates for poisoning in the most and least deprived electoral wards.

RESULTS

Children in the most deprived wards had admission rates for medicinal poisoning that were 2-3 times higher than those in the least deprived wards (IRR 2.49, 95% CI 1.87 to 3.30). Admission rates for non-medicinal poisoning were about twice as high in the most compared to the least deprived wards (IRR 1.77, 95% CI 1.19 to 2.64). Deprivation gradients were particularly steep for benzodiazepines (IRR 5.63, 95% CI 1.72 to 18.40), antidepressants (IRR 4.58, 95% CI 1.80 to 11.66), cough and cold remedies (IRR 3.93, 95% CI 1.67 to 9.24), and organic solvents (IRR 3.69, 95% CI 1.83 to 7.44).

CONCLUSIONS

There are steep deprivation gradients for admissions to hospital for childhood poisoning, with particularly steep gradients for some psychotropic medicines. Interventions to reduce these inequalities should be directed towards areas of greater deprivation.

Diagnoses of HIV-1 and HIV-2 in England, Wales, and Northern Ireland associated with west Africa

OBJECTIVES

To describe HIV diagnoses, including those of HIV-2 infection, made in England, Wales, and Northern Ireland (E,W&NI) among those probably infected in west Africa, and to consider whether there is evidence for ongoing heterosexual transmission within the United Kingdom.

METHODS

Reports of new HIV diagnoses received at the Communicable Disease Surveillance Centre were analysed. Individuals probably infected in west Africa and those infected through heterosexual intercourse within the United Kingdom by a heterosexual partner infected in west Africa were included.

RESULTS

Between 1985 and 2003 inclusive, 1324 individuals diagnosed and reported with HIV had probably been infected in west Africa, with 222 diagnoses made in 2003. 917 (69%) were HIV-1 infected and 52 (6%) HIV-2 or HIV-1/HIV-2 co-infected. For 355 (27%) the HIV type was not reported. The proportion of HIV-2 and HIV-1/HIV-2 infections varied by country of infection (p<0.001): ranging from the Gambia (11.7%-15.2%) to Nigeria (0.7%-1.0%). A further 130 individuals were probably infected through heterosexual intercourse within the United Kingdom by a heterosexual partner infected in west Africa. 89 (68%) were HIV-1 infected and three (2%) HIV-2 infected or HIV-1/HIV-2 co-infected. For 38 (29%) HIV type was not reported.

CONCLUSION

The number of people infected with HIV in west Africa and diagnosed in E,W&NI has increased in recent years, and there is evidence of heterosexual transmission within the United Kingdom from people infected in west Africa. While numbers of HIV-2 diagnoses remain relatively low, an appreciable proportion of people infected in some west African countries and diagnosed in the United Kingdom may be HIV-2 positive, with implications for prognosis and treatment.

The changing epidemiology of prevalent diagnosed HIV infections in England, Wales, and Northern Ireland, 1997 to 2003

OBJECTIVES

To present the current epidemiology of prevalent diagnosed HIV infections in England, Wales, and Northern Ireland (E, W, & NI) and describe trends over time.

METHODS

Descriptive analyses of the annual national Survey of Prevalent HIV Infections Diagnosed (SOPHID) for the period 1997 to 2003.

RESULTS

In 2003, 34 251 adults (15 years of age or over) were seen for HIV related care in E, W, & NI, representing a 17% increase in the prevalence of diagnosed HIV infections compared with 2002 and a 132% increase compared with 1997. Between 1997 and 2003, as a proportion of total prevalent cases, adults who acquired their infection through heterosexual sex increased from 26% to 49%; black African adults increased from 15% to 35% and diagnosed adults resident in London fell from 62% to 55% of the total. The male to female ratio declined from 5:1 to 2:1. The proportion of adults receiving combination antiretroviral therapy increased from 53% in 1998 to 64% in 2003.

CONCLUSION

There has been a large increase in the number of adults with diagnosed HIV infection seen for care in E, W, & NI since 1997. Changes in the epidemiology of prevalent diagnosed HIV were seen by sex, route of infection, ethnicity, level of antiretroviral therapy, and areas of residence and treatment. In 2003, for the first time, prevalent diagnosed infections acquired through heterosexual sex over-took those acquired through sex between men. These increases have serious implications for the planning and financing of HIV services in the United Kingdom.

The role of rectocele repair in targeted patients with obstructed defaecation

INTRODUCTION

Obstructed defaecation is a complex disorder that poses serious management challenges. The purpose of this study is to review the functional results of surgery in women undergoing rectocele repair for obstructed defaecation, and in a targeted subgroup in which the rectocele was the only identifiable cause of their symptoms.

METHODS

All case notes were reviewed. Demographic details, preoperative symptoms, details of previous pelvic surgery, radiological and anorectal physiology results, operative procedure, post operative symptoms, length of follow-up and details of further pelvic reconstructive surgery were recorded. To enter the targeted group, patients (i) had not undergone previous pelvic surgery, (ii) had presented with obstructive defaecation, (iii) had a proctogram that demonstrated a rectocele with no or partial intrarectal intussusception and (iv) had no other functional abnormality in colonic transit studies, endoanal ultrasound or anorectal physiology.

RESULTS

Eighty-two case notes were reviewed. All experienced obstructed defaecation. Forty-two women underwent a per-anal plication of the rectocele, 33 had a transperineal plication and levatorplasty and seven a mesh repair. A total of 63 (77%) women were pleased with the result, though symptoms later returned in 17 (27%) of them. 26 (31%) had further surgery in an attempt to improve their defaecatory difficulties. Sixteen women were eligible for the targeted group. All had a good early result though symptoms returned in three women. Two (12%) had further surgery.

CONCLUSION

Careful preoperative patient selection is vital to improve outcomes. Preoperative counselling of all patients undergoing rectocele repair is of extreme importance, in particular explaining the evolving nature of pelvic floor dysfunction and the possible need for further reconstructive surgery.