Instructional Models for Course-Based Research Experience (CRE) Teaching

The course-based research experience (CRE) with its documented educational benefits is increasingly being implemented in science, technology, engineering, and mathematics education. This article reports on a study that was done over a period of 3 years to explicate the instructional processes involved in teaching an undergraduate CRE. One hundred and two instructors from the established and large multi-institutional SEA-PHAGES program were surveyed for their understanding of the aims and practices of CRE teaching. This was followed by large-scale feedback sessions with the cohort of instructors at the annual SEA Faculty Meeting and subsequently with a small focus group of expert CRE instructors. Using a qualitative content analysis approach, the survey data were analyzed for the aims of inquiry instruction and pedagogical practices used to achieve these goals. The results characterize CRE inquiry teaching as involving three instructional models: 1) being a scientist and generating data; 2) teaching procedural knowledge; and 3) fostering project ownership. Each of these models is explicated and visualized in terms of the specific pedagogical practices and their relationships. The models present a complex picture of the ways in which CRE instruction is conducted on a daily basis and can inform instructors and institutions new to CRE teaching.

Genomic diversity of bacteriophages infecting Microbacterium spp

The bacteriophage population is vast, dynamic, old, and genetically diverse. The genomics of phages that infect bacterial hosts in the phylum Actinobacteria show them to not only be diverse but also pervasively mosaic, and replete with genes of unknown function. To further explore this broad group of bacteriophages, we describe here the isolation and genomic characterization of 116 phages that infect Microbacterium spp. Most of the phages are lytic, and can be grouped into twelve clusters according to their overall relatedness; seven of the phages are singletons with no close relatives. Genome sizes vary from 17.3 kbp to 97.7 kbp, and their G+C% content ranges from 51.4% to 71.4%, compared to ~67% for their Microbacterium hosts. The phages were isolated on five different Microbacterium species, but typically do not efficiently infect strains beyond the one on which they were isolated. These Microbacterium phages contain many novel features, including very large viral genes (13.5 kbp) and unusual fusions of structural proteins, including a fusion of VIP2 toxin and a MuF-like protein into a single gene. These phages and their genetic components such as integration systems, recombineering tools, and phage-mediated delivery systems, will be useful resources for advancing Microbacterium genetics.

Monitoring the past and choosing the future: the prefrontal cortical influences on voluntary action

Choosing between equivalent response options requires the resolution of ambiguity. One could facilitate such decisions by monitoring previous actions and implementing transient or arbitrary rules to differentiate response options. This would reduce the entropy of chosen actions. We examined voluntary action decisions during magnetoencephalography, identifying the spatiotemporal correlates of stimulus- and choice-entropy. Negative correlations between frontotemporal activity and entropy of past trials were observed after participants’ responses, reflecting sequential monitoring of recent events. In contrast, choice entropy correlated negatively with prefrontal activity, before and after participants’ response, consistent with transient activation of latent response-sets ahead of a decision and updating the monitor of recent decisions after responding. Individual differences in current choices were related to the strength of the prefrontal signals that reflect monitoring of the statistical regularities in previous events. Together, these results explain individual expressions of voluntary action, through differential engagement of prefrontal areas to guide sequential decisions.

Development, Validation, and Application of the Microbiology Concept Inventory

If we are to teach effectively, tools are needed to measure student learning. A widely used method for quickly measuring student understanding of core concepts in a discipline is the concept inventory (CI). Using the American Society for Microbiology Curriculum Guidelines (ASMCG) for microbiology, faculty from 11 academic institutions created and validated a new microbiology concept inventory (MCI). The MCI was developed in three phases. In phase one, learning outcomes and fundamental statements from the ASMCG were used to create T/F questions coupled with open responses. In phase two, the 743 responses to MCI 1.0 were examined to find the most common misconceptions, which were used to create distractors for multiple-choice questions. MCI 2.0 was then administered to 1,043 students. The responses of these students were used to create MCI 3.0, a 23-question CI that measures students' understanding of all 27 fundamental statements. MCI 3.0 was found to be reliable, with a Cronbach's alpha score of 0.705 and Ferguson's delta of 0.97. Test item analysis demonstrated good validity and discriminatory power as judged by item difficulty, item discrimination, and point-biserial correlation coefficient. Comparison of pre- and posttest scores showed that microbiology students at 10 institutions showed an increase in understanding of concepts after instruction, except for questions probing metabolism (average normalized learning gain was 0.15). The MCI will enable quantitative analysis of student learning gains in understanding microbiology, help to identify misconceptions, and point toward areas where efforts should be made to develop teaching approaches to overcome them.

Tales of diversity: Genomic and morphological characteristics of forty-six Arthrobacter phages

The vast bacteriophage population harbors an immense reservoir of genetic information. Almost 2000 phage genomes have been sequenced from phages infecting hosts in the phylum Actinobacteria, and analysis of these genomes reveals substantial diversity, pervasive mosaicism, and novel mechanisms for phage replication and lysogeny. Here, we describe the isolation and genomic characterization of 46 phages from environmental samples at various geographic locations in the U.S. infecting a single Arthrobacter sp. strain. These phages include representatives of all three virion morphologies, and Jasmine is the first sequenced podovirus of an actinobacterial host. The phages also span considerable sequence diversity, and can be grouped into 10 clusters according to their nucleotide diversity, and two singletons each with no close relatives. However, the clusters/singletons appear to be genomically well separated from each other, and relatively few genes are shared between clusters. Genome size varies from among the smallest of siphoviral phages (15,319 bp) to over 70 kbp, and G+C contents range from 45-68%, compared to 63.4% for the host genome. Although temperate phages are common among other actinobacterial hosts, these Arthrobacter phages are primarily lytic, and only the singleton Galaxy is likely temperate.

Prophage-mediated defence against viral attack and viral counter-defence

Temperate phages are common, and prophages are abundant residents of sequenced bacterial genomes. Mycobacteriophages are viruses that infect mycobacterial hosts including Mycobacterium tuberculosis and Mycobacterium smegmatis, encompass substantial genetic diversity and are commonly temperate. Characterization of ten Cluster N temperate mycobacteriophages revealed at least five distinct prophage-expressed viral defence systems that interfere with the infection of lytic and temperate phages that are either closely related (homotypic defence) or unrelated (heterotypic defence) to the prophage. Target specificity is unpredictable, ranging from a single target phage to one-third of those tested. The defence systems include a single-subunit restriction system, a heterotypic exclusion system and a predicted (p)ppGpp synthetase, which blocks lytic phage growth, promotes bacterial survival and enables efficient lysogeny. The predicted (p)ppGpp synthetase coded by the Phrann prophage defends against phage Tweety infection, but Tweety codes for a tetrapeptide repeat protein, gp54, which acts as a highly effective counter-defence system. Prophage-mediated viral defence offers an efficient mechanism for bacterial success in host-virus dynamics, and counter-defence promotes phage co-evolution.

Concept Inventory Development Reveals Common Student Misconceptions about Microbiology

Misconceptions, or alternative conceptions, are incorrect understandings that students have incorporated into their prior knowledge. The goal of this study was the identification of misconceptions in microbiology held by undergraduate students upon entry into an introductory, general microbiology course. This work was the first step in developing a microbiology concept inventory based on the American Society for Microbiology's Recommended Curriculum Guidelines for Undergraduate Microbiology. Responses to true/false (T/F) questions accompanied by written explanations by undergraduate students at a diverse set of institutions were used to reveal misconceptions for fundamental microbiology concepts. These data were analyzed to identify the most difficult core concepts, misalignment between explanations and answer choices, and the most common misconceptions for each core concept. From across the core concepts, nineteen misconception themes found in at least 5% of the coded answers for a given question were identified. The top five misconceptions, with coded responses ranging from 19% to 43% of the explanations, are described, along with suggested classroom interventions. Identification of student misconceptions in microbiology provides a foundation upon which to understand students' prior knowledge and to design appropriate tools for improving instruction in microbiology.

New species Victoriopisa bruneiensis and Apocorophium acutum (Chevreux, 1908) from Brunei (Crustacea: Peracarida: Amphipoda)

One new and one invasive species of amphipod are described from the subtidal waters of Brunei. The new species Victoriopisa bruneiensis (Melitidae) and the invasive species Apocorophium acutum (Chevereux, 1908) (Corophiidae) were collected from the Sungai Brunei Estuary. Victoriopisa bruneiensis sp. nov. is one of only four Victoriopisa where the eyes are present. An updated key to twelve world species of Victoriopisa is provided. Apocorophium acutum occurs in high density algal matts on pylons/rocks. This is the sixth species of Apocorophium described for the genus.

Two new species of Lysianassidae Dana, 1849 from Australia: Riwo zeidleri and Socarnella delectabilis (Crustacea: Peracarida: Amphipoda)

The new species Riwo zeidleri and Socarnella delectabilis are described. Prior to this study Riwo Lowry & Stoddart, 1995 was a monotypic genus, while Socarnella Walker, 1904 consisted of only two described species. The distribution of Riwo is expanded southwards from northern Papua New Guinea and the Great Barrier Reef to the south coast of Australia and the distribution of Socarnella is expanded further southward from Sri Lanka and the South China Sea, to the west coast of Australia.

A broadly implementable research course in phage discovery and genomics for first-year undergraduate students

Engaging large numbers of undergraduates in authentic scientific discovery is desirable but difficult to achieve. We have developed a general model in which faculty and teaching assistants from diverse academic institutions are trained to teach a research course for first-year undergraduate students focused on bacteriophage discovery and genomics. The course is situated within a broader scientific context aimed at understanding viral diversity, such that faculty and students are collaborators with established researchers in the field. The Howard Hughes Medical Institute (HHMI) Science Education Alliance Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) course has been widely implemented and has been taken by over 4,800 students at 73 institutions. We show here that this alliance-sourced model not only substantially advances the field of phage genomics but also stimulates students' interest in science, positively influences academic achievement, and enhances persistence in science, technology, engineering, and mathematics (STEM) disciplines. Broad application of this model by integrating other research areas with large numbers of early-career undergraduate students has the potential to be transformative in science education and research training.

IMPORTANCE

Engagement of undergraduate students in scientific research at early stages in their careers presents an opportunity to excite students about science, technology, engineering, and mathematics (STEM) disciplines and promote continued interests in these areas. Many excellent course-based undergraduate research experiences have been developed, but scaling these to a broader impact with larger numbers of students is challenging. The Howard Hughes Medical Institute (HHMI) Science Education Alliance Phage Hunting Advancing Genomics and Evolutionary Science (SEA-PHAGES) program takes advantage of the huge size and diversity of the bacteriophage population to engage students in discovery of new viruses, genome annotation, and comparative genomics, with strong impacts on bacteriophage research, increased persistence in STEM fields, and student self-identification with learning gains, motivation, attitude, and career aspirations.

New species of Nuuanu (Amphipoda: Nuuanuidae) from Norfolk Island, Torres Strait and the Cocos (Keeling) Islands

Three new species of Nuuanu, N. quintalana sp. nov., N. stuckeyorun sp. nov. and N. titaseyi sp. nov. are described from Norfolk Island, Tasman Sea; Cocos (Keeling) Islands, Indian Ocean and the Torres Strait, Australia, respectively. There are currently 17 described species of Nuuanu with the genus distributed world-wide.

A call for a community of practice to assess the impact of emerging technologies on undergraduate biology education

Recent recommendations for educational research encourage empirically tested, theory-based, completely transparent, and broadly applicable studies. In light of these recommendations, we call for a research standard and community of practice in the evaluation of technology use in the undergraduate life science classroom. We outline appropriate research methodology, review and critique the past research on technology usage and, lastly, suggest a new and improved focus for research on emerging technologies.

Cluster K mycobacteriophages: insights into the evolutionary origins of mycobacteriophage TM4

Five newly isolated mycobacteriophages –Angelica, CrimD, Adephagia, Anaya, and Pixie – have similar genomic architectures to mycobacteriophage TM4, a previously characterized phage that is widely used in mycobacterial genetics. The nucleotide sequence similarities warrant grouping these into Cluster K, with subdivision into three subclusters: K1, K2, and K3. Although the overall genome architectures of these phages are similar, TM4 appears to have lost at least two segments of its genome, a central region containing the integration apparatus, and a segment at the right end. This suggests that TM4 is a recent derivative of a temperate parent, resolving a long-standing conundrum about its biology, in that it was reportedly recovered from a lysogenic strain of Mycobacterium avium, but it is not capable of forming lysogens in any mycobacterial host. Like TM4, all of the Cluster K phages infect both fast- and slow-growing mycobacteria, and all of them – with the exception of TM4 – form stable lysogens in both Mycobacterium smegmatis and Mycobacterium tuberculosis; immunity assays show that all five of these phages share the same immune specificity. TM4 infects these lysogens suggesting that it was either derived from a heteroimmune temperate parent or that it has acquired a virulent phenotype. We have also characterized a widely-used conditionally replicating derivative of TM4 and identified mutations conferring the temperature-sensitive phenotype. All of the Cluster K phages contain a series of well conserved 13 bp repeats associated with the translation initiation sites of a subset of the genes; approximately one half of these contain an additional sequence feature composed of imperfectly conserved 17 bp inverted repeats separated by a variable spacer. The K1 phages integrate into the host tmRNA and the Cluster K phages represent potential new tools for the genetics of M. tuberculosis and related species.

Dynamic causal modelling of effective connectivity from fMRI: are results reproducible and sensitive to Parkinson's disease and its treatment?

Dynamic causal modelling (DCM) of functional magnetic resonance imaging (fMRI) data offers new insights into the pathophysiology of neurological disease and mechanisms of effective therapies. Current applications can be used both to identify the most likely functional brain network underlying observed data and estimate the networks' connectivity parameters. We examined the reproducibility of DCM in healthy subjects (young 18–48 years, n = 27; old 50–80 years, n = 15) in the context of action selection. We then examined the effects of Parkinson's disease (50–78 years, Hoehn and Yahr stage 1–2.5, n = 16) and dopaminergic therapy. Forty-eight models were compared, for each of 90 sessions from 58 subjects. Model-evidences clustered according to sets of structurally similar models, with high correlations over two sessions in healthy older subjects. The same model was identified as most likely in healthy controls on both sessions and in medicated patients. In this most likely network model, the selection of action was associated with enhanced coupling between prefrontal cortex and the pre-supplementary motor area. However, the parameters for intrinsic connectivity and contextual modulation in this model were poorly correlated across sessions. A different model was identified in patients with Parkinson's disease after medication withdrawal. In “off” patients, action selection was associated with enhanced connectivity from prefrontal to lateral premotor cortex. This accords with independent evidence of a dopamine-dependent functional disconnection of the SMA in Parkinson's disease. Together, these results suggest that DCM model selection is robust and sensitive enough to study clinical populations and their pharmacological treatment. For critical inferences, model selection may be sufficient. However, caution is required when comparing groups or drug effects in terms of the connectivity parameter estimates, if there are significant posterior covariances among parameters.

Pathways of pyrimidine salvage in Streptomyces

Using 5-fluoropyrimidine analogues, high-performance liquid chromatography (HPLC), and the feeding of pyrimidine compounds to pyrimidine auxotrophs, the pathways for salvage of exogenous pyrimidine nucleosides and bases in Streptomyces were established. Selection for resistance to the analogues resulted in the isolation of strains of S. griseus lacking the following enzyme activities: uracil phosphoribosyltransferase (upp) and cytidine deaminase (cdd). The conversion of substrates in the pathway was followed using reverse-phase HPLC. The strains deficient in salvage enzymes were also verified by this method. In addition, feeding of exogenous pyrimidines to strains lacking the biosynthetic pathway confirmed the salvage pathway. Data from the analogue, HPLC, and feeding experiments showed that Streptomyces recycles the pyrimidine base uracil, as well as the nucleosides uridine and cytidine. Cytosine is not recycled due to a lack of cytosine deaminase.

Cross-reactivity between related sequences found in Acinetobacter sp., Pseudomonas aeruginosa, myelin basic protein and myelin oligodendrocyte glycoprotein in multiple sclerosis

To investigate the possible role of molecular mimicry to bacterial components in multiple sclerosis (MS) pathogenesis we examined antibody responses to mimicry peptide sequences of Acinetobacter, Pseudomonas aeruginosa and myelin components. Antibodies to mimicry peptides from Acinetobacter (p<0.001), P. aeruginosa (p<0.001), myelin basic protein (MBP) (p<0.001) and myelin oligodendrocyte glycoprotein (MOG) (p<0.001) were significantly elevated in MS patients compared to controls. Antisera against MBP (residues 110-124) reacted with both Acinetobacter and Pseudomonas peptides from 4- and gamma-carboxymuconolactone decarboxylase, respectively. MOG (residues 43-57) antisera reacted with Acinetobacter peptide from 3-oxo-adipate-CoA-transferase subunit A. The role of these bacteria in MS is unclear but demonstrates that molecular mimicry is not restricted to viruses suggesting bacterial infections could play a role in MS pathogenesis. Further work is required to evaluate the relevance of these cross-reactive antibodies to the neuropathology of MS.

Antibodies to Acinetobacter bacteria and bovine brain peptides, measured in bovine spongiform encephalopathy (BSE) in an attempt to develop an ante-mortem test

Bovine spongiform encephalopathy (BSE) is a neurological disease of cattle. Antibody responses to Acinetobacter radioresistens and six other bacteria, as well as to bovine myelin basic protein and bovine neurofilaments were measured in 128 BSE positive animals, 63 BSE negative animals and 64 healthy control animals. Animals positive for BSE had the highest levels of antibodies to Acinetobacter radioresistens (p < 0.0001) and also autoantibodies to bovine myelin basic protein (p < 0.0001) and bovine neurofilaments (p < 0.0001). In an endeavour to develop an antemortem test for BSE, 12 different strains of Acinetobacter were further tested in a MAN (myelin-Acinetobacter-neurofilament) assay involving 28 BSE positive and 18 BSE negative animals and defined bovine brain peptides. Five out of the 12 Acinetobacter bacteria tested [Acinetobacter (sp3), A. haemolyticus (sp4), A. johnsonii (sp7), A. lwoffii (sp8) and Acinetobacter (sp9)] gave 100% sensitivity and 100% specificity for detecting BSE. The highest anti-bacterial antibody level compared to controls was obtained with A. johnsonii. Further field studies are required to determine the validity of the MAN assay in detecting animals affected with BSE.

Antibody responses to Acinetobacter spp. and Pseudomonas aeruginosa in multiple sclerosis: prospects for diagnosis using the myelin-acinetobacter-neurofilament antibody index

Antibody responses to Acinetobacter (five strains), Pseudomonas aeruginosa, Escherichia coli, myelin basic protein (MBP), and neurofilaments were measured in sera from 26 multiple sclerosis (MS) patients, 20 patients with cerebrovascular accidents (CVA), 10 patients with viral encephalitis, and 25 healthy blood donors. In MS patients, elevated levels of antibodies against all strains of Acinetobacter tested were present, as well as antibodies against P. aeruginosa, MBP, and neurofilaments, but not antibodies to E. coli, compared to the CVA group and controls. The myelin-Acinetobacter-neurofilament antibody index appears to distinguish MS patients from patients with CVAs or healthy controls. The relevance of such antibodies to the neuropathology of MS requires further evaluation.

Streptomyces aspartate transcarbamoylase is a dodecamer with dihydroorotase activity

Aspartate transcarbamoylase (ATCase) was purified from Streptomyces griseus. The enzyme is a dodecamer with a molecular mass of approximately 450 kDa. The holoenzyme is a complex of ATCase and active dihydroorotase (DHOase) subunits. The ATCase and DHOase activities co-purify after gel filtration and ion-exchange chromatography. Denaturing gel electrophoresis separates the holoenzyme into a 38-kDa ATCase polypeptide and a 47-kDa DHOase polypeptide. The holoenzyme retained ATCase and DHOase activity after being heated to 65 degrees C for 5 min, but after storage at 4 degrees C for 24 hours lost ATCase activity. Previously, the Pseudomonas putida Class A ATCase was defined by Schurr et al. (J Bacteriol 177, 1751-1759) as requiring an inactive DHOase to be functional. Here, we show that an active DHOase is part of the dodecameric ATCase/DHOase complex in Streptomyces. To distinguish those Class A ATCases with active DHOases from those with degenerate DHOases, we suggest the subdivision, Class A(1), for the former and Class A(2) for the latter.

Does local therapy affect survival rates in breast cancer?

BACKGROUND

The goal of this study was to challenge the hypothesis that local recurrence of breast cancer does not affect survival rates, by determining whether survival rates differ for conservative and radical surgical policies.

METHODS

This study used prospective long-term follow-up monitoring of two contemporaneous groups of patients, within a single unit, who were treated identically except for the one variable of local treatment policy, i.e., conservative or radical. A total of 451 patients with operable breast cancer were chosen from 567 consecutive patients with breast cancer who were treated between 1970 and 1979 in the University Department of Surgery. The rate of survival 132 months after treatment was used as an outcome measure.

RESULTS

Two hundred forty-one patients were treated using a conservative approach and 210 were treated using a radical approach. At 132 months, the survival rate (58% vs. 42%) and median survival time (> 132 vs. 100 months) were significantly improved for the radically treated group (P < .01). The treatment groups were comparable in terms of age, menopausal status, tumor size, histologic grading, and Nottingham Prognostic Index values. The advantage of the radical policy persisted when examined in relation to each of these prognostic factors.

CONCLUSIONS

Use of radical local treatment yielded a highly significant survival benefit (comparable to that obtained with adjuvant therapy), compared with a conservative approach. This was related to a reduced locoregional recurrence rate and provides evidence that local therapy influences long-term outcomes for patients with breast cancer. High-quality locoregional control should be emphasized, as is systemic therapy, in management policies. Assessment of surgical techniques, particularly in relation to locoregional recurrence rates, should be included in all studies in which surgery is a component of therapy.

Complications of latissimus dorsi myocutaneous flap breast reconstruction

AIMS

To review the experience of a single unit in post-mastectomy reconstruction using the latissimus dorsi flap.

METHODS

A retrospective review of 111 cases treated between 1984 and 1993. The notes were evaluated for type of procedure, associated treatment and complications.

RESULTS

A significant morbidity of this procedure was demonstrated with 41 (37%) patients requiring a second operation during the period of the study. The majority of these second operations were related to the prosthesis used to achieve symmetry. Second operations were more common in those who had saline-filled prostheses. Other complications seen included wound infection, small areas of flap necrosis, hypertrophic scars and problems with the donor scar. No differences in complication rates were demonstrated for delayed vs immediate procedures or for patients receiving or not receiving radiotherapy. No life-threatening complication were seen during the study.

CONCLUSIONS

The latissimus dorsi reconstruction is reliable but the overall programme is beset with considerable morbidity. This factor needs to be taken into consideration when discussing reconstructive options with the post-mastectomy patient.

The continuing challenge of parastomal hernia: failure of a novel polypropylene mesh repair

In an attempt to reduce the high recurrence rate after repair of parastomal hernia, a technique was devised in which non-absorbable mesh was used to provide a permanent closure of the gap between the emerging bowel and abdominal wall. Seven patients were treated during the period 1990-1992. Five-year follow-up has given disappointing results, with recurrent hernia in 29% of cases and serious complications, including obstruction and dense adhesions to the intra-abdominal mesh, in 57% and a mesh-related abscess in 15% of cases. This study highlights a dual problem--failure of a carefully sutured mesh to maintain an occlusive position, and complications of the mesh itself. The poor results obtained with this technique together with the disappointing results with other methods described in the literature confirms that parastomal hernia presents a continuing challenge.

A randomized controlled trial of prophylactic isolated cytotoxic perfusion for poor-prognosis primary melanoma of the lower limb

A randomized controlled trial of prophylactic isolated hyperthermic limb perfusion (IHLP) using melphalan at 2 mg/kg body weight has been performed on a total of 30 patients with primary melanoma of the lower limb > or = 1.7 mm thick. Excision (control, n = 14) was compared to excision plus IHLP (n = 16). The two groups were well matched for sex, tumour thickness and duration of follow-up (control group median: 63 months (range: 16-108), perfusion group median: 80 months (range: 37-113)). Recurrent disease developed in nine of the control group, seven of whom have died. In the perfusion group only two patients have developed recurrent disease, both of whom have died (recurrence: P < 0.004, mortality: P < 0.03, using Fishers' exact probability test). Inguino-femoral nodal recurrence occurred in five of nine control patients, but in only one patient in the perfusion group. These data support the use of adjuvant IHLP in the management of poor-prognosis primary melanoma of the lower limb.

Ileostomy polyps, adenomas, and adenocarcinomas

Ileostomy polyps are uncommon and poorly described. The aim of this study was to undertake a retrospective clinicopathological review of ileostomy polyps. Seven patients with 60 polyps arising on ileostomies performed for ulcerative colitis were studied. The histopathological evaluation of archival ileostomy biopsy specimens, polypectomy or excision specimens, and clinical review of patient records was undertaken. Fifty of 60 polyps were inflammatory cap polyps and six further polyps were composed of granulation tissue only. They occurred anywhere on the stoma at any time after ileostomy construction and were strongly associated with overt stomal prolapse. Four neoplastic polyps were identified in two patients 27-36 years after ileostomy construction; all occurred at the mucocutaneous junction. One patient presented with a 2 cm polypoid invasive adenocarcinoma while in the second a 1.7 cm polypoid mucinous adenocarcinoma and a 0.7 cm ileal tubular adenoma with high grade dysplasia occurred at the site of excision of a cap polyp showing focal low grade adenomatous dysplasia six years previously. Neoplastic and non-neoplastic polyps could not be differentiated clinically. It was found that most ileostomy polyps are inflammatory cap polyps associated with stomal prolapse. Less common are polypoid adenomas or adenocarcinomas arising at the mucocutaneous anastomosis > 20 years after ileostomy construction. To prevent ileostomy carcinoma it is recommended that a biopsy of all polyps at the mucocutaneous anastomosis and of any non-prolapse associated polyps elsewhere on the stoma occurring > 15 years after ileostomy construction is done.

A case of squamous cell carcinoma complicating hidradenitis suppurativa

A case of extensive squamous cell carcinoma arising in widespread perianal and inguinal hidradenitis suppurativa is used to illustrate the pathological features which influence management. The surgical pathology, with wide extension along subcutaneous sinuses, frequently leads to the view that it is incurable. A planned surgical approach, using both immediate frozen section and delayed paraffin histology to assess clearance margins allowed complete surgical excision in two stages. Colostomy is not a necessary part of management and healing by granulation is an acceptable alternative to extensive reconstruction procedures. Radiotherapy and chemotherapy, sometimes used in palliation mode, are not likely to be beneficial.

Anastomotic configuration does not affect recurrence of Crohn's disease after ileocolonic resection

The influence of anastomotic configuration on recurrence of symptomatic Crohn's disease has been assessed in a sequential study of patients undergoing resection of ileal Crohn's disease. Between 1972 and 1991 92 patients had 102 ileocolonic anastomoses constructed after resection of intestinal Crohn's disease. The configuration of the ileocolonic anastomosis was either end to side (ES, n = 68) or side to side (SS, n = 34). The majority of patients in both groups were female and both groups were similar for duration of Crohn's disease at resection, steroid therapy, previous number of intestinal resections, indication for surgery and length of ileum resected at operation. No anastomotic leak occurred in either group. A total of 39 patients developed symptomatic recurrent Crohn's disease including 31 (46%) in the ES group and 8 (24%) in the SS group. This difference was related to the length of follow-up, the annual rate of symptomatic recurrence was almost identical for both end to side (0.066) and side to side (0.052) anastomoses.

Parastomal pyoderma gangrenosum in inflammatory bowel disease

PURPOSE

Parastomal pyoderma gangrenosum is uncommon and its association with inflammatory bowel disease is unclear. This is a review of five patients with parastomal pyoderma gangrenosum.

METHODS

A retrospective review of five patients with ulcerative colitis (two patients) or Crohn's disease (three patients) who have been seen in one surgical unit was conducted.

RESULTS

All patients were females and each presented within nine months of abdominal surgery and stoma construction. All had active proctitis (n = 3) or perianal Crohn's disease (n = 2). Both patients with perianal Crohn's disease had a mild clinical course with healing of parastomal pyoderma gangrenosum when treated with steroids with and without low-dose cyclosporin A. They both had curettage of the perineal wound as well. In the remaining three patients with active proctitis, the parastomal lesions failed to resolve despite high-dose systemic steroids. By contrast, the parastomal pyoderma gangrenosum healed promptly in two of these patients following proctectomy for active proctitis.

CONCLUSION

The variable clinical outcome of parastomal pyoderma gangrenosum may be related to the activity of the underlying inflammatory bowel disease or possibly to low-grade perineal sepsis.

Bowel diversion should be used with caution in stenosing anal Crohn's disease

Proximal diversion has commonly been used for severe perianal Crohn's disease in an attempt to relieve local symptoms, whether the primary intestinal disease is in the colon or small bowel. Two patients are presented in whom diversion led to severe symptomatic disease in the previously normal defunctioned bowel. In each case the development of colonic disease was associated with increasing anal stenosis leading to retention of purulent fluid within the bowel lumen. Faecal stream diversion should be used with caution in stenosing anal Crohn's disease.

Timing of ileocolonic resection for symptomatic Crohn's disease--the patient's view

Eighty patients were asked if they would have preferred their ileocolonic resection and anastomosis for Crohn's disease, to have been carried out sooner, later or at the same time as it was done. Seventy of the patients replied (88%). No patient would have preferred their operation to have been later, while 74% thought it should have been earlier. A preferred operation time was given for 69 resections, between 0 months--that is, at the same time--and 15 years earlier. The median preferred operation time was 12 months earlier (95% confidence intervals 18 months earlier to 7 months earlier). The remaining 18 patients were satisfied with the timing of their operation. Reasons given for earlier surgery in 58 resections included the severity of Crohn's symptoms preoperatively (97%), the ability to eat normally after resection (86%), feeling of well being after the resection (62%), and abolishing the need for drugs (43%). Patients preferring an earlier operation time were less likely to have had a previous resection (13/58) than patients in the 'same time' group (10/21, chi 2 = 4.746; p < 0.05).