The PreOp flexible sigmoidoscopy trainer. Validation and early evaluation of a virtual reality based system

AIM

To demonstrate face and construct validity of a computer based flexible sigmoidoscopy trainer.

METHODS

The PreOp (Immersion Medical, USA) system is a virtual reality based flexible sigmoidoscopy simulator. The system records several performance parameters, such as percentage of colonic mucosa visualized, time taken, and pathlength of endoscope travel. Forty-five subjects were divided into three groups: novice (never performed a lower GI endoscopy), intermediate (5-50 examinations), and trained (greater than 200 examinations). After initial familiarization subjects were assessed three times on a case module. Results showed a nonparametric distribution.

RESULTS

There was a significant difference between all three groups with respect to percentage of mucosa visualized (novice 71.0 +/- 3.7%, intermediate 77.3 +/- 5.6%, expert 84.8 +/- 4.6%, Kruskal-Wallis p <0.001) and efficiency ratio (%mucosa/time, novice 0.163 +/- 0.055, intermediate 0.259 +/- 0.07, expert 0.306 +/- 0.058, p <0.001). The novice group was also slower and had a lower pathlength of instrument travel compared to the others.

CONCLUSION

PreOp virtual reality simulator is a valid discriminator of flexible sigmoidoscopic experience. Its effect on training needs to be explored.

Practice distribution in procedural skills training: a randomized controlled trial

BACKGROUND

"Massed" and "distributed" practice are important concepts in the acquisition of fine motor skills, and may be important in training in procedural skills.

METHODS

A total of 41 novice subjects were recruited and randomized to three groups to receive training on the MIST VR surgical trainer. There were 14 subjects in each of groups A and B and 13 subjects in group C. Training comprised 20 min of massed practice for group A, 20 min of distributed practice in 5 min blocks for group B, and 15 min of distributed practice in 5-min blocks for group C. Following the training period, all groups had a 5-min rest period, followed by a 5-min retention test. Comparisons were made between groups A and B, and groups A and C.

RESULTS

There was a statistically significant difference between groups A and B (p = 0.023) on the retention test, with group B performing better. The increment between the groups was 19% for the overall score on MIST VR. There were also significant differences in the time taken to complete the task during the training phase (p = 0.023, training blocks 3 and 4). Graphical representation suggests no effect between groups A and C, and statistical analysis confirms that the observed difference in median score is not significant.

CONCLUSION

This study demonstrates a benefit for distributed practice over massed practice in learning laparoscopic surgical skills on the MIST VR surgical trainer. This finding has potential implications for skills training in all areas of medicine.

Assessment of surgical competence

This paper examines the issues that arise in the broad area of competence assessment in surgical practice, with particular reference to the objective assessment of technical skill which has historically been the weakest aspect of assessment in surgical training. To facilitate a thorough appraisal of competence, a simple model of surgical practice is advanced, followed by a review of both current and experimental methods of assessing technical skill. The review comprises not only the published literature, but also work (both from the authors' and other groups) that is in progress or under consideration for publication. Significant issues in the implementation of these new technologies, especially the necessary further validation, and the imperative to demonstrate that the process introduced does indeed improve the outcomes are discussed.

Assessment of surgical competence

This paper examines the issues that arise in the broad area of competence assessment in surgical practice, with particular reference to the objective assessment of technical skill which has historically been the weakest aspect of assessment in surgical training. To facilitate a thorough appraisal of competence, a simple model of surgical practice is advanced, followed by a review of both current and experimental methods of assessing technical skill. The review comprises not only the published literature, but also work (both from the authors' and other groups) that is in progress or under consideration for publication. Significant issues in the implementation of these new technologies, especially the necessary further validation, and the imperative to demonstrate that the process introduced does indeed improve the outcomes are discussed.

The use of electromagnetic motion tracking analysis to objectively measure open surgical skill in the laboratory-based model

BACKGROUND

Technical performance has traditionally been assessed subjectively within the operating theater, with few successful attempts at objective analysis. The Imperial College Surgical Assessment Device (ICSAD) has already been shown to be a valid quantitative measure of dexterity in laparoscopic surgical simulation. We describe its application to the assessment of open surgical procedures.

STUDY DESIGN

Fifty-one participants were recruited from four different levels of general surgical experience: basic surgical trainees (n = 12), junior specialist registrars (n = 13), senior specialist registrars (n = 13), and consultants (n = 13). They completed two tasks: a small bowel anastomosis and a vein patch insertion into an artery. Surgical performance was measured with the Imperial College Surgical Assessment Device, a motion analysis system that measures the number of hand movements made and time taken to complete a task. The four groups were compared statistically using the Kruskal-Wallis test (K-W). Pairwise group comparisons used the Mann-Whitney U test and p values were adjusted for multiple comparisons to determine the statistical significance of these comparisons.

RESULTS

Mean values for number of movements and time (secs) for small bowel anastomosis were 2,080/1,236 (basic surgical trainees), 1,673/1,016 (junior specialist registrars), 1,375/862 (senior specialist registrars), and 1,337/782 (consultants), respectively. Comparison of the medians by K-W revealed a p < 0.001 for each variable (No. of movements, time), respectively. Mean vein patch insertion results were 1,653/1,258, 1,297/1,006, 1,090/912, and 925/736 for each of the four groups. Again, comparison of the medians by K-W revealed a p < 0.001 for each variable.

CONCLUSIONS

These findings suggest that hand motion analysis may be an effective objective measure of dexterity in open surgical simulation.

Nuclear factor-kappa B is upregulated in colorectal cancer

BACKGROUND

Chemoresistance may involve the anti-apoptotic transcriptional regulator, nuclear factor-kappa B (NF-kappa B). The purpose of this study was to determine whether chemotherapy induces NF-kappa B activation in a human colon cancer cell line (SW48) and whether NF-kappa B is constitutively activated in colorectal cancer.

METHODS

SW48 cells were incubated with gemcitabine hydrochloride (Gemzar) in the presence and absence of the 26s proteasome inhibitor, MG132, and NF-kappa B binding (electrophoretic mobility shift assay), DNA synthesis (tritiated thymidine uptake), cell viability (3-[4,5-dimethylthiazol-2-yl]-diphenyl-tetrazolium bromide assay), and apoptosis (caspase-3 activity) were measured at 24 hours. NF-kappa B binding (electrophoretic mobility shift assay) was also assayed in 10 colorectal cancer tumors.

RESULTS

SW48 cells demonstrated constitutive NF-kappa B binding that was enhanced by gemcitabine hydrochloride in a dose-dependent manner. MG132 inhibited NF-kappa B binding and enhanced gemcitabine hydrochloride's inhibition of DNA synthesis (gemcitabine hydrochloride = 73% +/- 1.4% vs gemcitabine hydrochloride + MG132 = 6% +/- 0.4%, P <.05), cell killing (gemcitabine hydrochloride = 87% +/- 2.0 vs gemcitabine hydrochloride + MG132 = 25% +/- 1.3%, P <.05), and caspase-3 activity (gemcitabine hydrochloride = 870 +/- 17.4 vs gemcitabine hydrochloride + MG132 = 1075 +/- 20.4, P <.05). NF-kappa B binding was increased in 8 of 10 colorectal cancer tumors compared with adjacent normal mucosa.

CONCLUSIONS

Gemcitabine hydrochloride enhances NF-kappa B binding in a colorectal cancer cell line, whereas inhibition of NF-kappa B enhances gemcitabine hydrochloride's antitumor activity. NF-kappa B is also activated in human colorectal cancer. NF-kappa B may identify chemoresistant tumors, whereas inhibition of NF-kappa B may be a novel, biologically based therapy. (Surgery 2001;130:363-9).

Web-based surgical educational tools

This paper describes work being undertaken as part of the WebSET (Web-based Standard Educational Tools) project. The project is producing a standardised suite of interactive three-dimensional educational tools, delivered across the WWW. The major focus will be the use of open technology and standards, and the production of learning components that can be used as building blocks for further development in a wide range of application areas. Two learning disciplines have been selected for the development of the WebSET tools: surgical training, and physiological education. A high quality consortium from across Europe has been assembled with complementary skills in the technologies needed by the project. The project is partly funded by the European Commission.

Upper-limb function in Australian children with traumatic brain injury: A controlled, prospective study

OBJECTIVE

To describe upper-limb function in children with mild and severe traumatic brain injury (TBI), by using both quantitative and qualitative measures.

DESIGN

Controlled, prospective cohort study with assessment points initially, at 6 months, and at 2 years after TBI.

SETTING

A tertiary pediatric trauma center in Australia.

PATIENTS

Fifty-one children, ranging in age up to 14 years, who were consecutive admissions with TBI. On the basis of initial and persisting abnormal coma score and persistence of posttraumatic amnesia, they were assigned to either a mild (n = 26) or a severely injured (n = 25) group. Thirty children admitted with non-TBI trauma were recruited as a control group.

MAIN OUTCOME MEASURES

Quantitative measures included Bruininks-Oseretsky Test of Motor Proficiency and Peabody Developmental Motor Scales. Qualitative measures included Brunnstrom Recovery Stages (adapted), categoric scales of muscle tone, grasp used when handwriting, quality of writing product, bilateral activity, and splint use.

RESULTS

There was little difference between the groups on the standardized assessments for subjects who could complete the tests. Qualitative measures showed the severe TBI group to have more difficulties with gross arm control, hand control, and hand function.

CONCLUSION

Children with severe TBI experience more and persisting difficulties with upper-limb function. It is essential to include both quantitative and qualitative measures in this type of research.

Gonadal development in mammals at the cellular and molecular levels

In mammals, although sex is determined chromosomally, gonads in both sexes begin development as similar structures. Until recently it was widely held that female development constituted a "default" pathway of development, which would occur in the absence of a testis-determining gene. This master gene on the Y chromosome, SRY in the human and Sry in the mouse, is thought to act in a cell-autonomous fashion to determine that cells in the gonadal somatic population develop as pre-Sertoli cells. Triggering of somatic cell differentiation along the Sertoli cell pathway is therefore a key event; it was thought that further steps in gonadal differentiation would follow in a developmental cascade. In the absence of Sertoli cells, the lack of anti-Mullerian hormone would allow development of the female Mullerian duct and absence of Leydig cells would prevent maintenance of the Wolffian duct. Recent findings that female signals not only maintain the Mullerian duct and repress the Wolffian duct but also suppress the development of Leydig cells and maintain meiotic germ cells, together with the finding that an X-linked gene is required for ovarian development and must be silenced in the male, have shown that the female default pathway model is an oversimplification. Morphological steps in gonadal differentiation can be correlated with emerging evidence of molecular mechanisms; growth factors, cell adhesion, and signaling molecules interact together, often acting within short time windows via reciprocal control relationships.

E-cadherin in the developing mouse gonad

Expression of the cell adhesion molecule E-cadherin in the developing mouse has been investigated by immunocytochemistry and disaggregated organ culture. The principal aims were firstly, to determine whether E-cadherin is expressed in the indifferent gonad and if so with which cell population(s) it is associated. Secondly, to investigate the pattern of expression in the mesonephros, especially in relation to ventral mesonephric tubule cells, which contribute to the somatic cell population of the gonad. Thirdly, to discover whether there are any sex differences in expression of E-cadherin in differentiating gonads. Germ cells in the indifferent gonad showed strong immunoreactivity whereas somatic cells were unstained unless their membranes were in contact with those of germ cells. Positive staining for E-cadherin was found in epithelial cells of the mesonephric duct and tubules. Staining was weak at the ventral margins of the ventral mesonephric tubules. At later stages, germ cell immunoreactivity could be correlated with stages of ovarian differentiation, being reduced or absent between germ cells at 16 days post coitum, when ovigerous cords become dissociated as a prelude to follicle formation. Stronger staining reappeared briefly at 17 days post coitum, the time of follicular cell attachment to oocytes, before waning again 2 days later. Similarly, immunoreactivity in the differentiating testis was initially restricted to the germ cell population but pre-Sertoli cells were strongly positive between 16 and 19 days post coitum. The most striking sex difference was seen in the somatic cell population, where Leydig cells of the testis became strongly positive for E-cadherin from 17 days post coitum onwards. At this time, unlike controls, dissociated cells from gonads of either sex were unable to reform their initial contacts when cultured in the presence of the antibody to E-cadherin, confirming its functional importance.

Ultrastructural studies demonstrate that epithelial polarity is established in cultured mouse pre-Sertoli cells by extracellular matrix components

The effect of three different substrates, laminin, fibronectin and reconstituted basement membrane, on isolated mouse pre-Sertoli cells maintained in vitro has been investigated. Cultures were monitored on a daily basis by phase contrast microscopy, and processed for light and electron microscopy at the end of the culture period. Extra-cellular matrix components have been found to influence Sertoli cell differentiation: both fibronectin and laminin promoted cell adhesion and differentiation, though laminin cultures showed poor viability. Pre-Sertoli cells cultured on reconstituted basement membrane showed the highest degree of differentiation, developing a polarized epithelial phenotype and forming cord-like aggregates; such cultures provide a model system for the investigation of factors involved with gonadal differentiation.

Postnatal development of Leydig cells in the opossum (Monodelphis domestica): an immunocytochemical and endocrinological study

This study involved characterization of Leydig cells of the opossum Monodelphis domestica, functionally by immunocytochemical identification of the enzyme 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and by measurement of testosterone levels using RIA. Immunostaining for 3 beta-HSD was first detected in a few Leydig cells on Day 16, was increased by Day 24, reached a peak at 4 mo, and was present even in senescent (3 yr) animals. Plasma testosterone was first measurable (0.35 nM) at prepuberty (3.5 mo). Prior to that, plasma testosterone concentrations were uniformly below the level of detection (< 0.3 nM) in both sexes from Day 5 to 2.5 mo. By 4 mo (puberty), plasma testosterone levels in males had risen significantly to 1.53 +/- 0.35 nM, continuing to increase to 1.79 +/- 0.4 nM at 6 mo and peaking at 2.71 +/- 0.29 nM in the adult (1-2 yr). Ovarian testosterone concentrations were consistently lower than those in the testis, as were those of adrenals of both sexes. Thus the testis would appear to be the major source of androgen production throughout life in this species. Our immunocytochemical study suggests that in Monodelphis, puberty is reached at 4 mo, and this was further supported by a rise in circulating testosterone levels at this time.

The AmMYB308 and AmMYB330 transcription factors from antirrhinum regulate phenylpropanoid and lignin biosynthesis in transgenic tobacco

MYB-related transcription factors are known to regulate different branches of flavonoid metabolism in plants and are believed to play wider roles in the regulation of phenylpropanoid metabolism in general. Here, we demonstrate that overexpression of two MYB genes from Antirrhinum represses phenolic acid metabolism and lignin biosynthesis in transgenic tobacco plants. The inhibition of this branch of phenylpropanoid metabolism appears to be specific to AmMYB308 and AmMYB330, suggesting that they recognize their normal target genes in these transgenic plants. Experiments with yeast indicate that AmMYB308 can act as a very weak transcriptional activator so that overexpression may competitively inhibit the activity of stronger activators recognizing the same target motifs. The effects of the transcription factors on inhibition of phenolic acid metabolism resulted in complex modifications of the growth and development of the transgenic plants. The inhibition of monolignol production resulted in plants with at least 17% less lignin in their vascular tissue. This reduction is of importance when designing strategies for the genetic modification of woody crops.

The AmMYB308 and AmMYB330 transcription factors from antirrhinum regulate phenylpropanoid and lignin biosynthesis in transgenic tobacco

MYB-related transcription factors are known to regulate different branches of flavonoid metabolism in plants and are believed to play wider roles in the regulation of phenylpropanoid metabolism in general. Here, we demonstrate that overexpression of two MYB genes from Antirrhinum represses phenolic acid metabolism and lignin biosynthesis in transgenic tobacco plants. The inhibition of this branch of phenylpropanoid metabolism appears to be specific to AmMYB308 and AmMYB330, suggesting that they recognize their normal target genes in these transgenic plants. Experiments with yeast indicate that AmMYB308 can act as a very weak transcriptional activator so that overexpression may competitively inhibit the activity of stronger activators recognizing the same target motifs. The effects of the transcription factors on inhibition of phenolic acid metabolism resulted in complex modifications of the growth and development of the transgenic plants. The inhibition of monolignol production resulted in plants with at least 17% less lignin in their vascular tissue. This reduction is of importance when designing strategies for the genetic modification of woody crops.

Testis development in the opossum Monodelphis domestica

Testis development in the grey short-tailed opossum, Monodelphis domestica, was investigated by light and electron microscopy in 180 animals. On the day of birth, half the karyotyped males were found to have histologically differentiated testes. By day (d) 1 testicular cords were clearly distinguished in all XY gonads and the tunica albuginea was fully developed. At this stage the large and pale primordial germ cells could be differentiated from dark pre-Sertoli cells. From d 3 the testis became progressively rounded and testicular cords were surrounded by peritubular cells. Leydig cells were then distinguishable by the expected ultrastructural features of steroidogenically active cells, showing abundant vesicles of SER, extensive mitochondria with tubular cristae and numerous lipid inclusions. Subsequently these cells formed clusters and were surrounded by envelope cells until wk 12. Testes were located in the abdomen, attached to the large mesonephroi, until d 24 after birth when they began their descent to the scrotal sac. From 7 wk the interstitial tissue became less cellular. At the prepubertal stage (12 wk), the seminiferous tubules lacked lumina. Leydig cell cytoplasm was electron-dense with increased amounts of SER forming parallel profiles. By 4 mo (pubertal stage), seminiferous tubules were patent and various spermatogenic stages, including spermatozoa, were seen for the first time. Leydig cells then greatly outnumbered other interstitial tissue cells and were closely-packed around blood vessels but no longer clustered by envelope cells; their SER was very highly organised into masses of parallel arrays and lipid inclusions were reduced. In the adult (1 y) Leydig cells reached their greatest size; their morphological features resembled those seen at 4 mo except that lipid inclusions were sparse. In ageing Leydig cells (2-3 y), large amounts of SER were present but disorganised.

Pseudomonas aeruginosa outbreak associated with a contaminated blood-gas analyser in a neonatal intensive care unit

Over a 10 month period in a neonatal intensive care unit there was an outbreak of infection caused by Pseudomonas aeruginosa (resistant to ticarcillin, timentin) which involved 24 newborns. There was extensive morbidity and mortality (38%) associated with the infections, which presented as septicaemia (N = 6) (five succumbed and four had coexisting pneumonia), pneumonia (N = 6), meningitis (one, died), conjunctivitis (N = 1), otitis externa (N = 1), conjunctivitis plus otitis externa (N = 1). In addition there were two pseudosepticaemias and six colonized infants, three of whom were treated for the presence of P. aeruginosa in endotracheal aspirates. There was always at least one baby colonized or infected with P. aeruginosa during the outbreak. Environmental surveillance and genomic DNA fingerprinting of isolates identified the blood gas analyzer port as the likely reservoir for the outbreak. Further spread of the organism did not occur after commencement of staff education on vigilant and careful handwashing, especially after use of the blood-gas analyser.

Spatial distribution of acid-volatile sulphide concentration and metal bioavailability in mangrove sediments from the Brisbane River, Australia

Acid-volatile sulphide (AVS) was measured at regular positions along eight transects through a mangrove forest in the Brisbane River, Queensland, Australia. Concentrations ranged from 0.33 to 22.61 micromol S g(-1) sediment dry weight. There was no correlation between AVS concentration and the proportion of clay-sand in the sediment, but sediments with high AVS concentrations tended to contain more water (rs=0.43; p=0.01). AVS concentrations were used to assess the potential bioavailability of the sediment heavy metal burden. The spatial variability of potential bioavailability was high and depended to a great extent on which metals were considered as part of the AVS complexing system. It is suggested seasonal variations would further increase the observed variability in bioavailability. This variation should be taken into account when monitoring and assessing long-term trends in sediment toxicity.

The social adjustment of deaf adolescents in segregated parially integrated and mainstreamed settings

This study examined the social adjustment of deaf adolescents enrolled in segregated (&egr; = 39), partially integrated (&egr; = 15), and mainstreamed (&egr; = 17) settings, comparing them with a control group of hearing students (&egr; = 88). Segregated students showed the lowest levels of adjustment overall. Partially integrated students reported better adjustment overall. Partially integrated students reported better adjustment than mainstreamed students with deaf peers; mainstreamed students reported better adjustment than partially integrated students with hearing peers, showing the same levels of adjustment with hearing peers as hearing students. Regardless of placement, deaf students reported better or equal adjustment with deaf than with hearing peers. Social adjustment with deaf peers was related to American Sign Language (ASL) skill and adjustment with hearing peers to spoken English. These findings suggest tht deaf students can benefit from both segregated and integrated placements as complememtary forms of social experience that each contribute to overal adjustment.

Firesetting during the preschool period: assessment and intervention issues

OBJECTIVE

To describe a methodology of assessing preschoolers involved in firesetting incidents, and outline the psychiatric implications of firesetting incidents in young children.

METHOD

To outline The Arson Prevention Program for Children and present case vignettes.

RESULTS

The heightened risk of burn injury or fatality in fires caused by young children is highlighted and practical suggestions for facilitating the immediate safety of the child and family are presented.

CONCLUSION

Despite the popular notion that fire interest and play is relatively benign in young children, the cases show that, as with older children, firesetting in preschoolers can be associated with serious child and/or family psychopathology.

An urban outbreak of visceral leishmaniasis in Natal, Brazil

The epidemiological pattern of visceral leishmaniasis in north-eastern Brazil is changing. The disease was typically seen in rural, endemic areas, but is now occurring as an epidemic in the city of Natal where 316 cases have been reported since 1989; 49% were in children less than 5 years of age. The principle clinical and laboratory findings were weight loss, fever, hepato-splenomegaly, anaemia, leucopenia and hypergammaglobulinaemia. Elevated transaminases and hyperbilirubinaemia were also observed. The diagnosis was confirmed in 87% of cases by identifying amastigotes in aspirates from bone marrow or spleen. Five isolates were identified as Leishmania (L.) chagasi by isoenzyme analysis. The mortality rate was 9%; all deaths occurred during the first week in hospital. One person had concurrent human immunodeficiency virus infection. Among 210 household contacts and neighbours of patients from the endemic area examined for evidence of L. (L.) chagasi infection, 6 additional cases of visceral leishmaniasis were diagnosed. Thirty-eight percent of house-mates and neighbours gave a positive Montenegro skin test reaction, indicating prior subclinical infection.