CRISPR gRNA phenotypic screening in zebrafish reveals pro-regenerative genes in spinal cord injury

Zebrafish exhibit robust regeneration following spinal cord injury, promoted by macrophages that control post-injury inflammation. However, the mechanistic basis of how macrophages regulate regeneration is poorly understood. To address this gap in understanding, we conducted a rapid in vivo phenotypic screen for macrophage-related genes that promote regeneration after spinal injury. We used acute injection of synthetic RNA Oligo CRISPR guide RNAs (sCrRNAs) that were pre-screened for high activity in vivo. Pre-screening of over 350 sCrRNAs allowed us to rapidly identify highly active sCrRNAs (up to half, abbreviated as haCRs) and to effectively target 30 potentially macrophage-related genes. Disruption of 10 of these genes impaired axonal regeneration following spinal cord injury. We selected 5 genes for further analysis and generated stable mutants using haCRs. Four of these mutants (tgfb1a, tgfb3, tnfa, sparc) retained the acute haCR phenotype, validating the approach. Mechanistically, tgfb1a haCR-injected and stable mutant zebrafish fail to resolve post-injury inflammation, indicated by prolonged presence of neutrophils and increased levels of il1b expression. Inhibition of Il-1β rescues the impaired axon regeneration in the tgfb1a mutant. Hence, our rapid and scalable screening approach has identified functional regulators of spinal cord regeneration, but can be applied to any biological function of interest.

Organotypic Brain Slice Culture Microglia Exhibit Molecular Similarity to Acutely-Isolated Adult Microglia and Provide a Platform to Study Neuroinflammation

Microglia are central nervous system (CNS) resident immune cells that have been implicated in neuroinflammatory pathogenesis of a variety of neurological conditions. Their manifold context-dependent contributions to neuroinflammation are only beginning to be elucidated, which can be attributed in part to the challenges of studying microglia in vivo and the lack of tractable in vitro systems to study microglia function. Organotypic brain slice cultures offer a tissue-relevant context that enables the study of CNS resident cells and the analysis of brain slice microglial phenotypes has provided important insights, in particular into neuroprotective functions. Here we use RNA sequencing, direct digital quantification of gene expression with nCounter® technology and targeted analysis of individual microglial signature genes, to characterize brain slice microglia relative to acutely-isolated counterparts and 2-dimensional (2D) primary microglia cultures, a widely used in vitro surrogate. Analysis using single cell and population-based methods found brain slice microglia exhibited better preservation of canonical microglia markers and overall gene expression with stronger fidelity to acutely-isolated adult microglia, relative to in vitro cells. We characterized the dynamic phenotypic changes of brain slice microglia over time, after plating in culture. Mechanical damage associated with slice preparation prompted an initial period of inflammation, which resolved over time. Based on flow cytometry and gene expression profiling we identified the 2-week timepoint as optimal for investigation of microglia responses to exogenously-applied stimuli as exemplified by treatment-induced neuroinflammatory changes observed in microglia following LPS, TNF and GM-CSF addition to the culture medium. Altogether these findings indicate that brain slice cultures provide an experimental system superior to in vitro culture of microglia as a surrogate to investigate microglia functions, and the impact of soluble factors and cellular context on their physiology.

Aberrant oligodendroglial-vascular interactions disrupt the blood-brain barrier, triggering CNS inflammation

Disruption of the blood-brain barrier (BBB) is critical to initiation and perpetuation of disease in multiple sclerosis (MS). We report an interaction between oligodendroglia and vasculature in MS that distinguishes human white matter injury from normal rodent demyelinating injury. We find perivascular clustering of oligodendrocyte precursor cells (OPCs) in certain active MS lesions, representing an inability to properly detach from vessels following perivascular migration. Perivascular OPCs can themselves disrupt the BBB, interfering with astrocyte endfeet and endothelial tight junction integrity, resulting in altered vascular permeability and an associated CNS inflammation. Aberrant Wnt tone in OPCs mediates their dysfunctional vascular detachment and also leads to OPC secretion of Wif1, which interferes with Wnt ligand function on endothelial tight junction integrity. Evidence for this defective oligodendroglial-vascular interaction in MS suggests that aberrant OPC perivascular migration not only impairs their lesion recruitment but can also act as a disease perpetuator via disruption of the BBB.

Kir4.1-Dependent Astrocyte-Fast Motor Neuron Interactions Are Required for Peak Strength

Diversified neurons are essential for sensorimotor function, but whether astrocytes become specialized to optimize circuit performance remains unclear. Large fast α-motor neurons (FαMNs) of spinal cord innervate fast-twitch muscles that generate peak strength. We report that ventral horn astrocytes express the inward-rectifying K⁺ channel Kir4.1 (a.k.a. Kcnj10) around MNs in a VGLUT1-dependent manner. Loss of astrocyte-encoded Kir4.1 selectively altered FαMN size and function and led to reduced peak strength. Overexpression of Kir4.1 in astrocytes was sufficient to increase MN size through activation of the PI3K/mTOR/pS6 pathway. Kir4.1 was downregulated cell autonomously in astrocytes derived from amyotrophic lateral sclerosis (ALS) patients with SOD1 mutation. However, astrocyte Kir4.1 was dispensable for FαMN survival even in the mutant SOD1 background. These findings show that astrocyte Kir4.1 is essential for maintenance of peak strength and suggest that Kir4.1 downregulation might uncouple symptoms of muscle weakness from MN cell death in diseases like ALS.

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Kir4.1 is upregulated in astrocytes around high-activity alpha motor neurons (MNs)

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Astrocyte Kir4.1 KO caused decreased peak strength without alpha MN loss

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ALS patient-derived astrocytes show cell-autonomous Kir4.1 downregulation

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Astrocyte Kir4.1 regulates MN size through PI3K/mTOR/pS6 activation

Oligodendrocyte precursors migrate along vasculature in the developing nervous system

Oligodendrocytes myelinate axons in the central nervous system and develop from oligodendrocyte precursor cells (OPCs) that must first migrate extensively during brain and spinal cord development. We show that OPCs require the vasculature as a physical substrate for migration. We observed that OPCs of the embryonic mouse brain and spinal cord, as well as the human cortex, emerge from progenitor domains and associate with the abluminal endothelial surface of nearby blood vessels. Migrating OPCs crawl along and jump between vessels. OPC migration in vivo was disrupted in mice with defective vascular architecture but was normal in mice lacking pericytes. Thus, physical interactions with the vascular endothelium are required for OPC migration. We identify Wnt-Cxcr4 (chemokine receptor 4) signaling in regulation of OPC-endothelial interactions and propose that this signaling coordinates OPC migration with differentiation.

Dysregulation of locus coeruleus development in congenital central hypoventilation syndrome

Human congenital central hypoventilation syndrome (CCHS), resulting from mutations in transcription factor PHOX2B, manifests with impaired responses to hypoxemia and hypercapnia especially during sleep. To identify brainstem structures developmentally affected in CCHS, we analyzed two postmortem neonatal-lethal cases with confirmed polyalanine repeat expansion (PARM) or Non-PARM (PHOX2B∆8) mutation of PHOX2B. Both human cases showed neuronal losses within the locus coeruleus (LC), which is important for central noradrenergic signaling. Using a conditionally active transgenic mouse model of the PHOX2B∆8 mutation, we found that early embryonic expression (<E10.5) caused failure of LC neuronal specification and perinatal respiratory lethality. In contrast, later onset (E11.5) of PHOX2B∆8 expression was not deleterious to LC development and perinatal respiratory lethality was rescued, despite failure of chemosensor retrotrapezoid nucleus formation. Our findings indicate that early-onset mutant PHOX2B expression inhibits LC neuronal development in CCHS. They further suggest that such mutations result in dysregulation of central noradrenergic signaling, and therefore, potential for early pharmacologic intervention in humans with CCHS.

Environmental factors in a population-based inception cohort of inflammatory bowel disease patients in Europe--an ECCO-EpiCom study

BACKGROUND AND AIMS

The incidence of inflammatory bowel disease (IBD) is increasing in Eastern Europe possibly due to changes in environmental factors towards a more "westernised" standard of living. The aim of this study was to investigate differences in exposure to environmental factors prior to diagnosis in Eastern and Western European IBD patients.

METHODS

The EpiCom cohort is a population-based, prospective inception cohort of 1560 unselected IBD patients from 31 European countries covering a background population of 10.1 million. At the time of diagnosis patients were asked to complete an 87-item questionnaire concerning environmental factors.

RESULTS

A total of 1182 patients (76%) answered the questionnaire, 444 (38%) had Crohn's disease (CD), 627 (53%) ulcerative colitis (UC), and 111 (9%) IBD unclassified. No geographic differences regarding smoking status, caffeine intake, use of oral contraceptives, or number of first-degree relatives with IBD were found. Sugar intake was higher in CD and UC patients from Eastern Europe than in Western Europe while fibre intake was lower (p<0.01). Daily consumption of fast food as well as appendectomy before the age of 20 was more frequent in Eastern European than in Western European UC patients (p<0.01). Eastern European CD and UC patients had received more vaccinations and experienced fewer childhood infections than Western European patients (p<0.01).

CONCLUSIONS

In this European population-based inception cohort of unselected IBD patients, Eastern and Western European patients differed in environmental factors prior to diagnosis. Eastern European patients exhibited higher occurrences of suspected risk factors for IBD included in the Western lifestyle.

Olig1 function is required to repress dlx1/2 and interneuron production in Mammalian brain

Abnormal GABAergic interneuron density, and imbalance of excitatory versus inhibitory tone, is thought to result in epilepsy, neurodevelopmental disorders, and psychiatric disease. Recent studies indicate that interneuron cortical density is determined primarily by the size of the precursor pool in the embryonic telencephalon. However, factors essential for regulating interneuron allocation from telencephalic multipotent precursors are poorly understood. Here we report that Olig1 represses production of GABAergic interneurons throughout the mouse brain. Olig1 deletion in mutant mice results in ectopic expression and upregulation of Dlx1/2 genes in the ventral medial ganglionic eminences and adjacent regions of the septum, resulting in an ∼30% increase in adult cortical interneuron numbers. We show that Olig1 directly represses the Dlx1/2 I12b intergenic enhancer and that Dlx1/2 functions genetically downstream of Olig1. These findings establish Olig1 as an essential repressor of Dlx1/2 and interneuron production in developing mammalian brain.

An 8-week brain MRI follow-up analysis of rat eosinophilic meningitis caused by Angiostrongylus cantonensis infection

Early differential diagnosis and timely follow-up are advantageous in the management of Angiostrongylus cantonensis infection. This study aimed to characterize angiostrongyliasis in the rat brain for an 8-week period using magnetic resonance imaging (MRI) with contrast-enhanced T1-weighted images (T1WI), T2-weighted imaging (T2WI), fluid attenuation inversion recovery (FLAIR) and R2 mapping sequences. The data were analysed with Mathematica and Matlab software programs for weekly changes in each brain following the infection of 20, 50, 100 and 300 third-stage larvae (L3), respectively. The results showed that the average subarachnoid space detected by T2WI technique was peaked up to 10% increase of original size on day 35 after 100 or 300 larvae infection, while those infected with 20 or 50 larvae showed less than 4% increase during the entire course of observation. This increase was relevant to the mortality of the infected rats, because those with 100 or 300 larvae infections showed a sharp decrease in survival rate before day 40. After day 40, the average subarachnoid space was decreased, but the average ventricle size was persistently increased, with the highest increase observed in the group infected with 300 larvae on day 56. Furthermore, the R2 mapping mean and R2 mapping size were significantly different between the brains with severe infection (100 and 300 larvae groups together) and those with mild infection (20 and 50 larvae groups together) on day 49, but not on day 35. Our results showed that diagnosis for different quantity of larvae infection using MRI is possible and follow-up characterization is informative in revealing the effects of angiostrongyliasis on different brain areas. In conclusion, our results support the use of MRI as a non-invasive diagnostic technique for eosinophilic meningitis caused by A. cantonensis infection.

The role of Tal2 and Tal1 in the differentiation of midbrain GABAergic neuron precursors

Midbrain- and hindbrain-derived GABAergic interneurons are critical for regulation of sleep, respiratory, sensory-motor and motivational processes, and they are implicated in human neurological disorders. However, the precise mechanisms that underlie generation of GABAergic neuron diversity in the midbrain–hindbrain region are poorly understood. Here, we show unique and overlapping requirements for the related bHLH proteins Tal1 and Tal2 in GABAergic neurogenesis in the midbrain. We show that Tal2 and Tal1 are specifically and sequentially activated during midbrain GABAergic neurogenesis. Similar to Gata2, a post-mitotic selector of the midbrain GABAergic neuron identity, Tal2 expression is activated very early during GABAergic neuron differentiation. Although the expression of Tal2 and Gata2 genes are independent of each other, Tal2 is important for normal midbrain GABAergic neurogenesis, possibly as a partner of Gata2. In the absence of Tal2, the majority of midbrain GABAergic neurons switch to a glutamatergic-like phenotype. In contrast, Tal1 expression is activated in a Gata2 and Tal2 dependent fashion in the more mature midbrain GABAergic neuron precursors, but Tal1 alone is not required for GABAergic neuron differentiation from the midbrain neuroepithelium. However, inactivation of both Tal2 and Tal1 in the developing midbrain suggests that the two factors co-operate to guide GABAergic neuron differentiation in a specific ventro-lateral midbrain domain. The observed similarities and differences between Tal1/Tal2 and Gata2 mutants suggest both co-operative and unique roles for these factors in determination of midbrain GABAergic neuron identities.

Expression profiling of Aldh1l1-precursors in the developing spinal cord reveals glial lineage-specific genes and direct Sox9-Nfe2l1 interactions

Developmental regulation of gliogenesis in the mammalian CNS is incompletely understood, in part due to a limited repertoire of lineage-specific genes. We used Aldh1l1-GFP as a marker for gliogenic radial glia and later-stage precursors of developing astrocytes and performed gene expression profiling of these cells. We then used this dataset to identify candidate transcription factors that may serve as glial markers or regulators of glial fate. Our analysis generated a database of developmental stage-related markers of Aldh1l1+ cells between murine embryonic day 13.5-18.5. Using these data we identify the bZIP transcription factor Nfe2l1 and demonstrate that it promotes glial fate under direct Sox9 regulatory control. Thus, this dataset represents a resource for identifying novel regulators of glial development.

Regional astrocyte allocation regulates CNS synaptogenesis and repair

Astrocytes, the most abundant cell population in the central nervous system (CNS), are essential for normal neurological function. We show that astrocytes are allocated to spatial domains in mouse spinal cord and brain in accordance with their embryonic sites of origin in the ventricular zone. These domains remain stable throughout life without evidence of secondary tangential migration, even after acute CNS injury. Domain-specific depletion of astrocytes in ventral spinal cord resulted in abnormal motor neuron synaptogenesis, which was not rescued by immigration of astrocytes from adjoining regions. Our findings demonstrate that region-restricted astrocyte allocation is a general CNS phenomenon and reveal intrinsic limitations of the astroglial response to injury.

Regulated temporal-spatial astrocyte precursor cell proliferation involves BRAF signalling in mammalian spinal cord

Expansion of astrocyte populations in the central nervous system is characteristic of evolutionarily more complex organisms. However, regulation of mammalian astrocyte precursor proliferation during development remains poorly understood. Here, we used Aldh1L1-GFP to identify two morphologically distinct types of proliferative astrocyte precursors: radial glia (RG) in the ventricular zone and a second cell type we call an 'intermediate astrocyte precursor' (IAP) located in the mantle region of the spinal cord. Astrogenic RG and IAP cells proliferated in a progressive ventral-to-dorsal fashion in a tight window from embryonic day 13.5 until postnatal day 3, which correlated precisely with the pattern of active ERK signalling. Conditional loss of BRAF function using BLBP-cre resulted in a 20% decrease in astrocyte production, whereas expression of activated BRAFV600E resulted in astrocyte hyperproliferation. Interestingly, BRAFV600E mitogenic effects in astrocytes were restricted, in part, by the function of p16INK4A-p19(ARF), which limited the temporal epoch for proliferation. Together, these findings suggest that astrocyte precursor proliferation involves distinct RG and IAP cells; is subjected to temporal and spatial control; and depends in part on BRAF signalling at early stages of mammalian spinal cord development.

Corridors of migrating neurons in the human brain and their decline during infancy

The subventricular zone (SVZ) of many adult non-human mammals generates large numbers of new neurons destined for the olfactory bulb (OB)^1–6. Along the walls of the lateral ventricles, immature neuronal progeny migrate in tangentially-oriented chains that coalesce into a rostral migratory stream (RMS) connecting the SVZ to the OB. The adult human SVZ, in contrast, contains a hypocellular gap layer separating the ependymal lining from a periventricular ribbon of astrocytes⁷. Some of these SVZ astrocytes can function as neural stem cells in vitro, but their function in vivo remains controversial. An initial report finds few SVZ proliferating cells and rare migrating immature neurons in the RMS of adult humans⁷. In contrast, a subsequent study indicates robust proliferation and migration in the human SVZ and RMS^8,9. Here, we find that the infant human SVZ and RMS contain an extensive corridor of migrating immature neurons before 18 months of age, but, contrary to previous reports⁸, this germinal activity subsides in older children and is nearly extinct by adulthood. Surprisingly, during this limited window of neurogenesis, not all new neurons in the human SVZ are destined for the OB – we describe a major migratory pathway that targets the prefrontal cortex in humans. Together, these findings reveal robust streams of tangentially migrating immature neurons in human early postnatal SVZ and cortex. These pathways represent potential targets of neurological injuries affecting neonates.

Distinct modes of migration position oligodendrocyte precursors for localized cell division in the developing spinal cord

Establishment of the cytoarchitecture of the central nervous system reflects the stereotyped cell migration and proliferation of precursor cells during development. In vitro analyses have provided extensive information on the control of proliferation and differentiation of oligodendrocyte precursors (OPCs), but less is known about the migratory behavior of these cells in vivo. Here we utilize a transgenic mouse line expressing enhanced green fluorescent protein (EGFP) under the proteolipid protein promoter (PLP-EGFP mice) to visualize directly the behaviors of OPCs in developing spinal cord slices. During early development, OPCs disperse from their origin at the ventricular zone by using saltatory migration. This involves orientation of the cell with a leading edge toward the pial surface and alternating stationary and fast-moving phases and dramatic shape changes. Once cells exit the ventricular zone, they exhibit an exploratory mode of migration characterized by persistent translocation without dramatic changes in cell morphology. The control of migration, proliferation, and cytokinesis of OPCs appear to be closely linked. In netrin-1 mutant spinal cords that lack dispersal cues, OPC migration rates were not significantly different, but the trajectories were altered, and numbers of migrating cells were dramatically reduced. In contrast to DNA replication that occurs at the ventricular zone or throughout the spinal cord neuropil, cell division or cytokinesis of OPCs occurs predominantly at the interface between gray and white matters, with the majority of cleavage planes parallel to the pial surface. These studies suggest that positional cues are critical for regulating OPC behavior during spinal cord development.

Kimura's disease mimicking an earlobe keloid

Kimura's disease (KD) is a rare chronic inflammatory disorder of unknown aetiology. It usually presents as soft-tissue masses predominantly in the head or neck region. We report a case of an asymptomatic tumour on the left earlobe mimicking a keloid. The tumour was histopathologically diagnosed as KD. This case suggests the importance of conducting skin biopsies of keloidal lesions on head and neck regions, particularly in patients who have peripheral eosinophilia and increased IgE levels.

Experience of maintenance infliximab therapy for refractory ulcerative colitis from six centres in England

BACKGROUND

Infliximab is used for treatment of Crohn's disease and, following the Active Ulcerative Colitis Trials (ACT) 1 and 2, it has been used as rescue and maintenance therapy in moderate and severe ulcerative colitis (UC).

AIM

To report on English experience with maintenance infliximab in terms of response and colectomy rates and side-effect profile in UC.

METHODS

A retrospective audit conducted by using a web-based questionnaire filled in by 12 gastroenterologists from six English centres.

RESULTS

Of the 38 patients receiving induction with infliximab, 28 (73.6%) maintained an ongoing response (8-weekly infusions 5 mg/kg) for a mean duration of 16.8 months (range 4-59), with 21 (55.3%) being in remission. Three of 38 patients (7.9%) who also responded had a secondary loss of response after an average of 10 months (range 8-13); seven of 38 patients (18.4%) showed no response. The colectomy rate was seven of 38 (18.4%, five non-responders and two with secondary loss of response). Adverse effects occurred in five patients (13.2%). Two discontinued infliximab (alopecia, invasive breast cancer). The three less-severe adverse effects were acute and delayed-type hypersensitivity reactions and one persistent otitis media.

CONCLUSION

Our experience suggests acceptable response rates, colectomy rates and side-effect profile of maintenance therapy with infliximab in moderate and severe UC.

A model of the long-term cost effectiveness of scheduled maintenance treatment with infliximab for moderate-to-severe ulcerative colitis

BACKGROUND

Infliximab (IFX) has been shown to be efficacious in moderate-severe ulcerative colitis (UC). Aim To evaluate the cost-effectiveness of a scheduled maintenance treatment (SMT) with IFX in moderate-severe UC patients.

METHODS

A Markov model was constructed to simulate the progression of a cohort of moderate-severe UC patients treated with IFX (5 mg/kg) SMT. Transitions were estimated from two phase III trials of IFX (ACT I and ACT II). Standard care, comprising immunomodulators and/or corticosteroids was used as a comparator. Two separate treatment strategies were evaluated - continued treatment in IFX responders and continued treatment in IFX patients achieving remission. The dose of IFX was estimated for a 73 kg typical UC patient in the UK. The results were calculated over 10 years using a discount rate of 3.5% for costs and outcomes. The outcome measure was quality-adjusted life years (QALYs) estimated using EQ-5D. Sensitivity analyses explored the uncertainty around the results.

RESULTS

The incremental cost effectiveness ratio (ICER) for IFX was 27,424 pounds in the responder strategy and 19,696 pounds in the remission strategy at 10 years. In sensitivity analysis, the ICER for IFX in the responder strategy ranged from 21,066 pounds to 86,322 pounds and in the remission strategy ranged from 14,728 pounds to 46,765 pounds. The model time horizon and patient body weight were important factors affecting results.

CONCLUSION

Eight-week SMT with IFX appears to be a cost-effective treatment option for adult patients suffering from moderate to severe UC.

Endoscopic mucosal resection (EMR) in the management of large colo-rectal polyps

BACKGROUND

Colonoscopic polypectomy plays a major role in preventing colo-rectal cancer. However, resection of sessile, broad-based pedunculated and flat lesions carries a high risk of perforation. Endoscopic Mucosal Resection (EMR) may significantly reduce this risk. We aim to assess the safety and efficacy of EMR in our unit.

PATIENTS AND METHODS

A review of a prospective database over a 3-year period identified 87 patients who underwent endoscopic polypectomy for polyps in sizes from 10 to 50 mm, performed by two experienced endoscopists. A total of 33 EMRs were performed on 30 lesions in 24 of these patients.

RESULTS

Median size of lesions was 20 mm. Most were located in the rectum and sigmoid. 22 lesions were resected en-bloc while 8 were resected piecemeal. Histologically these lesions were predominantly adenomatous polyps. An incidental focus of adenocarcinoma was found in 7 lesions. Histologically complete excision was achieved in 10 lesions. Although histological completeness of excision was not confirmed in 19 lesions, repeat colonoscopy confirmed successful excision. Only one lesion was incompletely excised requiring surgical resection. Bleeding occurred during 2 EMRs, both times successfully controlled by further injection of adrenaline locally. There was no case of bowel perforation. Further surveillance colonoscopy was performed according to established guidelines. Median follow-up period was 21 months. None of the patients diagnosed with adenocarcinoma showed any evidence of recurrence.

CONCLUSION

Within our unit endoscopic mucosal resection appeared to be safe and effective procedure for resecting large colorectal polyps not suitable for conventional polypectomy. This data would support prompt referral of lesions fulfilling these criteria to specialist units offering this service to avoid unnecessary surgery.

Netrin-1 is required for the normal development of spinal cord oligodendrocytes

Successful CNS myelination is dependent on the correct localization of oligodendrocytes and their interactions with adjacent axons. In the spinal cord, oligodendrocyte precursors originate at the ventral midline and subsequently migrate to the white matter where they mature. In vitro studies suggest this dispersal is mediated by the guidance molecule netrin-1. Here, we show that in the spinal cord of netrin-1 mutant mice, oligodendrocyte precursors failed to disperse from the ventral midline as a consequence of a lack of polarization and directional migration. The lack of netrin-1 also resulted in an overall reduction of oligodendrocyte lineage cells that was independent of the failure of initial dispersal. Oligodendrocyte precursors injected into presumptive white matter underwent extensive radial migration and expansion in wild-type but not netrin-1 mutant hosts. These data indicate that netrin-1 is crucial for both the initial dispersal of spinal cord oligodendrocyte precursors and their subsequent development in the presumptive white matter.

Distally based sural island flap for the reconstruction of a large soft tissue defect in an open tibial fracture with occluded anterior and posterior tibial arteries—a case report

To repair a 10 x 16 cm soft tissue defect of right lower leg that accompanied with occluded anterior and posterior tibial arteries in a 30-year-old man who sustained comminuted type III(B) Gustilo open tibial and fibular fracture, we present a successful reconstruction by using a large distally based sural island flap perfused by the lowermost perforator of the peroneal artery. This flap is a useful alternative for distal extremity reconstruction when anterior and posterior tibial arteries are occluded, as large flaps can be elevated safely based on only one peroneal perforator.

Esomeprazole 20 mg on-demand is more acceptable to patients than continuous lansoprazole 15 mg in the long-term maintenance of endoscopy-negative gastro-oesophageal reflux patients: the COMMAND Study

BACKGROUND

Symptom relief, through adherence to appropriate maintenance therapy, is the sole objective of treatment for patients with endoscopy-negative gastro-oesophageal reflux disease.

AIM

To compare the efficacy of 'on-demand' treatment with esomeprazole 20 mg vs. continuous treatment with lansoprazole 15 mg daily in patients with endoscopy-negative gastro-oesophageal reflux disease.

METHODS

Endoscopy-negative gastro-oesophageal reflux disease patients who achieved complete resolution of heartburn after short-term (2-4 weeks) treatment with esomeprazole 20 mg (n = 774) were randomized to receive either esomeprazole 20 mg on-demand (n =311) or lansoprazole 15 mg continuous daily treatment (n = 311) for 6 months.

RESULTS

Significantly more patients were willing to continue taking esomeprazole on-demand than lansoprazole continuous therapy after 6 months (93% vs. 88%; P = 0.02). This superior outcome was achieved despite patients on esomeprazole requiring medication only 38% as often as those on lansoprazole, leading to direct cost savings of more than one-third (36%). Furthermore, patients receiving esomeprazole 20 mg on-demand were more satisfied with their treatment after 1 month compared with patients taking lansoprazole 15 mg continuously.

CONCLUSIONS

In patients with endoscopy-negative gastro-oesophageal reflux disease, esomeprazole 20 mg on-demand is more acceptable to patients and is an economically more effective treatment than lansoprazole 15 mg continuously.

Netrin 1 mediates spinal cord oligodendrocyte precursor dispersal

In spinal cord, oligodendrocyte precursors that give rise to myelin-forming cells originate in a restricted domain of the ventral ventricular zone. During development, these cells migrate widely throughout the spinal cord. Netrin 1 is expressed at the ventral ventricular zone during oligodendrocyte precursors emigration, and, in vitro, netrin 1 acts as chemorepellent and antagonizes platelet-derived growth factor (PDGF) chemoattraction. Oligodendrocyte precursors express the netrin receptors DCC and UNC5 and function-blocking anti-DCC antibody inhibits chemorepulsion of ventral spinal cord explants and netrin-secreting cells. In spinal cord slice preparations, addition of function-blocking anti-DCC antibody or netrin 1 dramatically inhibits oligodendrocyte precursor migration from the ventral ventricular zone. These data indicate the initial dispersal of oligodendrocyte precursors from their localized origin is guided by a chemorepellent response to netrin 1.

The chemokine receptor CXCR2 controls positioning of oligodendrocyte precursors in developing spinal cord by arresting their migration

Spinal cord oligodendrocytes originate in the ventricular zone and subsequently migrate to white matter, stop, proliferate, and differentiate. Here we demonstrate a role for the chemokine CXCL1 and its receptor CXCR2 in patterning the developing spinal cord. Signaling through CXCR2, CXCL1 inhibited oligodendrocyte precursor migration. The migrational arrest was rapid, reversible, concentration dependent, and reflected enhanced cell/substrate interactions. White matter expression of CXCL1 was temporo-spatially regulated. Developing CXCR2 null spinal cords contained reduced oligodendrocytes, abnormally concentrated at the periphery. In slice preparations, CXCL1 inhibited embryonic oligodendrocyte precursor migration, and widespread dispersal of postnatal precursors occurred in the absence of CXCR2 signaling. These data suggest that population of presumptive white matter by oligodendrocyte precursors is dependent on localized expression of CXCL1.

Eruption process of upper permanent canine

The purpose of this study was to investigate normal eruptive pattern of upper permanent canine. One hundred and fifty-one panoramic radiographs were used. Inclination of upper canine and lateral incisor, length and horizontal and vertical positions of cusp and root apex of the canine were evaluated. The canine erupted with increasing distal inclination and with no significant changes of the lateral incisor. Developmental changes of the canines relative to palatal plane and midline were shown by figures.

Glial cell migration directed by axon guidance cues

Widespread myelination by oligodendrocytes is essential for the normal functioning of the vertebrate CNS. Oligodendrocyte precursors initially arise in restricted regions of the neuroepithelium and migrate relatively long distances to their final destinations. The signals that guide this migration have remained poorly understood, but recent studies suggest that glial precursors use similar molecular cues to those that guide axons through the complex terrain of the developing CNS. For example, in the developing optic nerve, glial-precursor migration from the brain towards the retina is guided by netrin-1 and semaphorin 3a. These studies suggest a novel mechanism governing glial precursor migration and provide new insights into development and the potential to direct CNS injury repair.

Developmental changes of mandibular permanent canines and premolars in early mixed dentition

This study investigated the developmental changes of mandibular permanent canines and premolars in early mixed dentition using panoramic radiographs. Positions of cusps and root apices of the teeth relative to the inferior border of mandible were evaluated. The developmental stages of the teeth were divided into three stages. There were few changes in the inclination of the three teeth. The permanent canine began to erupt before stage 2 and the second premolar began to erupt after stage 2. The distance between the inferior border of the mandible and apices of the three teeth was almost fixed in early mixed dentition.

Localization of first permanent molars in lateral cephalometric and panoramic radiographs from early mixed dentition to early permanent dentition

Changes in position and mesiodistal angulations of maxillary and mandibular first permanent molars from early mixed dentition to early permanent dentition were measured on panoramic radiographs and compared with the values measured on lateral cephalometric radiographs. It was found that the maxillary and mandibular first permanent molars were uprighted gradually, drifted mesially and vertically, and that the changes in mesiodistal angulations were clearly on the panoramic radiographs in comparison with the cephalometric radiographs.

Morphological characteristics of the deciduous teeth

The morphology of the deciduous teeth was investigated. The mean mesiodistal crown dimensions of the deciduous canine, first and second molars and the mean buccolingual crown dimensions of the deciduous second molars in both dental arches of boys were significantly larger than that of girls. The upper deciduous first molar of girls was slender buccolingually and the lower deciduous second molar of boys was slender mesiodistally.

Cephalometric studies of children with long and short faces

The purpose of this study was to investigate the facial morphologic characteristics in children with long and short faces. Lateral cephalometric radiographs of 46 children with long faces and 42 children with short faces were used. Both boys and girls with long faces exhibited upright incisors, excessive upper dentoalveolar development, shorter posterior face height, shorter ramus height and mandibular body, greater gonial angle and backward rotation of mandible when compared with those with short faces.

Treatment of anterior crossbite with bilateral posterior crossbite in early mixed dentition: a case report

A case report of a 7-year-old boy who had Class III skeletal pattern is presented. The maxilla was deficient in anteroposterior and transverse dimensions, causing a slightly concave profile, a crossbite relationship of most of the anterior and posterior teeth, and upper anterior crowding. The rapid palatal expansion therapy effectively uprighted the posterior segments and developed the arches. Alignment, leveling and development of a good functional occlusion was accomplished with the .022" x .028" standard edgewise appliance.

Does better disease-related education improve quality of life? A survey of IBD patients

The importance of health-related quality of life (HRQOL) assessment in patients with chronic disorders such as inflammatory bowel disease (IBD) is now acknowledged by researchers. Of the many factors that may influence HRQOL, patient knowledge of the condition and disease-related information provision have hitherto not been studied. In all, 250 patients with inactive IBD (UC = 128, CD = 122) were randomly chosen from our IBD clinic. Two sets of questionnaires [initially a standard questionnaire to assess level of disease-related information by a patient information score (PIS), followed by a HRQOL questionnaire] were sent to each patient. In the PIS, a score of 7 or more indicated satisfactory disease-related knowledge and in the HRQOL, a score less than 51 suggested a normal QOL, and a score above 60 significantly impaired QOL. A total of 168 patients (66%) returned both the questionnaires (UC = 91, CD = 77). The mean QOL in patients with UC and CD was 62.2+/-8.3 and 63.9+/-9.5 respectively, (P = NS). 99 patients (59%) had significantly impaired QOL (mean score 65+/-7.6) with only 12 patients (8%), 6 in each group, having a normal QOL. Mean PIS score for the patients was 7.04+/-0.1; 53% of the UC patients and 75% of the CD patients (P = 0.006) were considered well informed (ie, PIS scores of 7 or more). The mean PIS for UC patients was 6.5+/-0.4 vs 7.5+/-0.2 for the CD group (P = 0.001). There was, however, no correlation seen between the QOL and PIS scores, both for UC and CD patients (R = 0.3). In conclusion, most patients with IBD have impaired QOL, despite of having inactive disease. The level of disease-related knowledge appears to be better in patients with CD, although that does not seem to affect QOL.

Tooth-position, arch-size, and arch-shape in the primary dentition

Tooth positions and dental arch forms are related to the growth of the cranio-facial complex. To determine the positions of primary teeth and size and shape of the primary dental arches, sixty dental casts of young children (thirty boys and thirty girls) with normal occlusions were examined. In all casts the coordinates of cusp tips of primary canines and molars, and mesial and distal line angles of primary canines and incisors were digitized. The computer-generated curves were made for the maxillary and mandibular arches using a polynomial model. The results show that there were three major cusp-to-fossa and one cusp-to-marginal ridge relations in primary molar intercuspation. On average, girl's dental arches were smaller than boy's dental arches. The mean curves of mandibular arches in anterior segments were gentler than those of maxillary arches.

Descriptive classification of variations in primary mandibular first molars

Variability in tooth morphology can play a significant role in the achievable results of restorative treatment. This study identified the variations of morphology of the primary mandibular first molar (Type I and II coronal outline and Type A-F cusp alignment.) Type I coronal outline was found more frequently (86 percent) than Type II (14 percent). 93 percent of the primary mandibular first molars comprise four cusps, 5 percent comprise five cusps, and 2 percent comprise 3 cusps (F). Among the four-cusp group, 70 percent had an oblique transverse ridge (C), 25 percent had a poorly developed transverse ridge (A). Among the five-cusp-group, 67 percent had a distal cusp (E), and 33 percent had a fifth lingual cusp (D). The most frequent combination of coronal outline and cusp alignment was Type I-C (60 percent), and followed by Type I-B (22 percent), II-C (5 percent), and II-A (4 percent).

Components of anterior crossbite in the primary dentition

The craniofacial and dental components of anterior crossbite children with a full primary dentition were investigated by means of a cephalometric and correlation study. A group of thirty-two Taiwanese children with anterior crossbite was compared to a group of thirty-two normal occlusion subjects. The facial profile polygon method was used for assessing morphological characteristics of craniofacial pattern. According to the results, early signs of anterior crossbite are present in the primary dentition. A smaller anterior cranial base, a retruded positioning of the maxilla and a smaller interincisal angle were found in the anterior crossbite children. A correlation analysis between all the cephalometric measurements was carried out, and the significance of the differences between correlation coefficients of the two groups was calculated. the normal occlusion group shows negative correlation between interincisal angle and FH-SGn angle. The anterior crossbite group shows positive correlation between FH-NPog angle and U1-FH angle.

Eruption process of the second molar

The second molar is located at the distal of the first molar, and we must be aware of its stage of development when we plan to move the first molar distally. Few researchers have investigated the development of second molars. The purpose of this study was to observe the eruption process of the maxillary and mandibular second molars by using 238 panoramic radiographs. The developmental stages of the second molar were divided into four stages: the whole crown calcified = stage 1; beginning root formation = stage 2; initial formation of the radicular bifurcation = stage 3; and the root length is equal to the crown height = stage 4. The mesiodistal crown width of the first and second molars, axial inclination and eruption rate of the second molar, and the space available for emergence of the second molar at each stage were measured, and the statistical analysis was made to assess the developmental changes. It was learned that the mandibular second molars began to erupt at stage 3 and the maxillary second molars at stage 2. The axial inclination of the mandibular second molars maintained almost the same angle and the maxillary second molars were uprighted gradually from stage 1 to 4. The available space increased significantly from stage 1 to 2 in both second molars. It is suggested that the space available for emergence of the second molar is prepared before stage 2, and then the tooth begins to erupt. As the maxillary second molars, there was further increase in the available space after stage 3. Negative correlation was seen between the mesiodistal crown width of the mandibular second molar and the available space in stage 2. Positive correlation was seen between the mesiodistal crown width of maxillary second molar and the available space in stage 3. It is suggested that greater increase in the space available for emergence of the second molar could be expected in the maxillary dental arch, if the mesiodistal crown width of the second molar required it.

The graded effect of hyperhomocysteinemia on the severity and extent of coronary atherosclerosis

It is not clear to what extent methylenetetrahydrofolate reductase (MTHFR) gene and hyperhomocysteinemia effect the severity and extent of coronary atherosclerosis in Asian populations. We examined the MTHFR genotypes and plasma homocysteine (HCY) concentrations in 192 Taiwanese and investigated their relationship with coronary artery disease (CAD), and the severity and extent of coronary atherosclerosis. The distribution of MTHFR genotypes was similar in 116 CAD patients and 76 non-CAD subjects. Homozygosity was noted in 8% of CAD patients and 13% of non-CAD subjects (P=0.33; 95% CI, 0. 2-1.6). The geometric mean of HCY values was higher in CAD patients (11.10+/-1.51 micromol/l) than in non-CAD subjects (9.21+/-1.55 micromol/l) (P=0.003). HCY levels were higher in patients with multi-vessel disease (P<0.05) or in patients with > or = 90% stenotic lesions (P=0.005), compared with non-CAD subjects. The CAD risks in the top two HCY quartiles (> or = 14.0 and 10.1-13.9 micromol/l) were 4.0 (95% CI, 1.7-9.2) and 3.2 (95% CI, 1.4-7.4) times higher than in the lowest quartile (< or = 7.9 micromol/l) (P=0.001 and 0.007, respectively). Linear regression analysis showed significant correlations between HCY concentrations and the severity and extent of atherosclerosis (P=0.0001 for both). In conclusion, hyperhomocysteinemia appears to have a graded effect on the risk of CAD as well as the severity and extent of coronary atherosclerosis. Our findings do not support the homozygous genotype of MTHFR as a genetic risk factor for CAD in this Taiwanese population. Perhaps a further study including assessment of vitamin status is needed to better clarify the relationship between MTHFR genotypes and CAD.

Vasculitic small bowel perforation masquerading as spontaneous bacterial peritonitis in a patient with decompensated liver disease

We report on a young patient with decompensated alcohol-induced liver disease (Child-Pugh score C) who presented with clinical, biochemical and radiological evidence suggestive of spontaneous bacterial peritonitis. She was however subsequently found to have multiple small bowel perforations, which were diagnosed only at laparotomy. The histology of the bowel showed evidence of vasculitis. This case illustrates two important points. Firstly, even if a patient has all the prerequisites to develop spontaneous bacterial peritonitis, a secondary cause of peritonitis (eg. bowel perforation or intra-abdominal abscess) must always be considered as a differential diagnosis and a repeat ascitic tap is mandatory after 48 h of antibiotic therapy to confirm a decrease in the white cell count. Secondly, it shows the rare co-existence of alcoholic liver disease and vasculitis.

Reaction of cyclohexylamine with hypochlorite and enhancement of oxidation of plasma sulfhydryl groups by hypochlorite in vitro

In this study we investigated the reaction of cyclamate and its major metabolite, cyclohexylamine (CyhNH2), with NaOCl. NaOCl at 100 microM was allowed to react with various concentrations of cyclamate and CyhNH2, and the reactivity was compared with those of reduced glutathione (GSH) and ascorbic acid. The results showed that CyhNH2 was less reactive with NaOCl than GSH but was slightly more reactive than ascorbic acid at concentrations below 50 microM. CyhNH2 at 75 and 100 microM did not further decrease NaOCl. Cyclamate was much less reactive than CyhNH2, with only 43% loss in NaOCl at 100 microM cyclamate. When human blood plasma was incubated with 0.75 microM NaOCl, inclusion of CyhNH2 enhanced oxidation of sulfhydryl groups in a concentration-dependent manner, with complete oxidation of SH groups at 7.5 mM CyhNH2. Cyclamate had no effect. This enhancement by CyhNH2 suggests the formation of reactive products from the reaction of CyhNH2 with NaOCl. Absorption spectra demonstrated that reaction of CyhNH2 with NaOCl at pH 7.4 produced N-monochloramine, as evidenced by the appearance of a new peak at 245 nm and by the disappearance of the 292-nm peak of NaOCl. Cyclamate, which contains a sulfamic acid instead of a primary amine, also reacted with NaOCl at pH 7.4, but the reaction was much less pronounced and the product was probably not monochloramine since the peak was at 270 nm rather than at 245 nm. Because cyclamate is an important sweetener in many countries for people with diabetes mellitus, the possibility exists that CyhNH2 may enhance oxidation of important proteins by HOCl/OCl-.

Differential excretion of leucocyte granule components in inflammatory bowel disease: implications for pathogenesis

1. Faecal excretion of the leucocyte primary granule component, myeloperoxidase, and of the secondary granule component, lactoferrin, were compared in inflammatory bowel disease and infective diarrhoea. 2. Faecal lactoferrin correlated with faecal myeloperoxidase in both inflammatory bowel disease (P = 0.0018; n = 32) and infective diarrhoea (P = 0.00013; n = 37), but inflammatory bowel disease was associated with a much higher faecal excretion of lactoferrin but lower excretion of myeloperoxidase than infective diarrhoea. As a consequence, the median ratio of lactoferrin/myeloperoxidase excretion (both expressed as ng/mg of protein) for inflammatory bowel disease was 7.5 (range 3.5-21.3) with similar values for ulcerative colitis (n = 18) and Crohn's disease (n = 14) compared with only 0.9 (range 0.4-2.3; P < 0.0001) for infective diarrhoea. In inflammatory bowel disease faecal lactoferrin and myeloperoxidase excretion remained increased even in clinical remission. 3. In subsequent immunohistochemical studies to assess the possible explanation for these findings, lactoferrin and myeloperoxidase were demonstrated within crypt abscesses and surface mucus, both in inflammatory bowel and in infective diarrhoea mucosal samples. There was a slight increase in the number of lactoferrin-containing cells in the mucosal samples from ulcerative colitis and in the submucosa of samples from Crohn's disease compared with infective diarrhoea, but these changes were not sufficient to account for the marked increase in faecal lactoferrin excretion in inflammatory bowel disease. 4. In all mucosal samples, including those from normal mucosa, lactoferrin was also shown to be contained within mast cells. 5. These results could best be explained by a different mechanism for leucocyte activation in inflammatory bowel disease compared with infective diarrhoea, and are compatible with selective secretion of secondary granule components, which include lactoferrin but not myeloperoxidase, as a result of leucocyte activation by N-formylated bacterial peptides in inflammatory bowel disease.

The production of neuraminidase and fucosidase by Helicobacter pylori: their possible relationship to pathogenicity

The pathogenicity of enterobacteria often correlates with their production of neuraminidase (sialidase). Forty-nine Helicobacter pylori isolates have therefore been examined for their production of neuraminidase and other glycosidases. All 49 isolates produced considerable neuraminidase (median 228 IU/microg protein, interquartile range 121-370), pH optimum 7.5. Nine of the 49 also produced fucosidase (median 23 IU/microg protein, interquartile range 12-39), pH optimum 7.0. Production of these enzymes did not correlate with bacterial Cag A expression or duodenal ulceration. Neutrophils exposed to neuraminidase show increased adherence to endothelium so the neuraminidase production by H. pylori could partly explain the predominant neutrophil inflammatory infiltrate seen in H. pylori-associated gastritis. Inhibition of this enzyme by use of neuraminidase-inhibitors could be a useful therapeutic approach.

Faecal mucinase activity assessed in inflammatory bowel disease using 14C threonine labelled mucin substrate

Previous studies have shown the presence in faeces of sulphatases, sialidases, glycosidases, and proteases relevant to mucus degradation, but the relative role of these enzymes in the degradation of colonic mucus has been unclear. A total mucinase assay using 14C threonine biologically labelled human colonic mucin as substrate was therefore developed in this study. Faecal mucinase activity of a pooled normal faecal filtrate was capable of removing 80% of the 14C threonine label from mucin within eight hours incubation, but 20% remained intact despite prolonged incubation. The pH profile of mucinase activity is broad (pH 4.5-9.5) suggesting contribution from multiple enzymes. Mucinase activity was reduced by preincubation with 100 micrograms/ml chymostatin (82.8%), 0.5 mg/ml EDTA (91.6%), and 4 g/l bismuth subsalicylate (72.0%). All 55 faecal samples studied contained detectable mucinase activity, measured as dpm release/micrograms protein/hour, which was greater in samples from patients with ulcerative colitis (n = 17, median 52.7, interquartile range 32.9-66.9), than controls (n = 26, 34.4, 26.8-40.4, p < 0.02) or patients with Crohn's disease (n = 12, 35.5, 17.5-55.7, p < 0.05). There was, however, no significant difference in faecal mucinase activity between inactive and active ulcerative colitis. These results suggest that faecal mucinase activity is one factor contributing to the thin mucus layer in ulcerative colitis and represents a potential target for drug treatment.

Increased faecal mucin sulphatase activity in ulcerative colitis: a potential target for treatment

Colonic mucin is heavily sulphated and it has been shown that enzymatic desulphation by faecal bacterial sulphatases greatly increases its susceptibility to degradation by faecal glycosidases. A possible role for faecal mucin sulphatase in the pathogenesis of inflammatory bowel disease has therefore been explored. Faecal mucin sulphatase activity assayed using 35S mucin as substrate was increased in ulcerative colitis (median 80.2 units/g pellet weight (range 6.9-1063; 95% confidence intervals (CI): 45.2 to 293.8, n = 22) compared with 11.3 units/g (range 3.0-53.5; 95% CI: 8.7 to 29.8, n = 17) in healthy controls (p < 0.01), where one unit released 1000 dpm free sulphate/hour from 35S mucin (1680 dpm/microgram). Patients with active ulcerative colitis had higher sulphatase activity (median 146; 95% CI: 98 to 253 units/g, n = 10) than those with inactive ulcerative colitis (median 42.2; CI: 22.5 to 81.6 units/g, n = 12) (p < 0.05). Longitudinal studies in patients with ulcerative colitis show fluctuations of faecal mucin sulphatase activity corresponding to clinical disease activity in six of seven patients. Faecal mucin sulphatase activity was not significantly increased in Crohn's disease (median 36.6, range 5.7-106.6; 95% CI: 22.9 to 65.3 units/g, n = 14). The bismuth salts, bismuth subcitrate and bismuth subsalicylate were found to inhibit faecal mucin sulphatase activity at concentrations achievable therapeutically. The increased faecal mucin sulphatase activity in ulcerative colitis could be the result of greater intraluminal substrate (mucin) availability leading to bacterial enzyme induction, but would probably result in more rapid degradation of secreted mucin and represents a potential target for treatment.

Increased rate of sialylation of colonic mucin by cultured ulcerative colitis mucosal explants

Sialylation of mucus glycoproteins confers charge and increased resistance to enzymatic degradation. The hypothesis that mucus sialylation might be altered in ulcerative colitis has been studied using in vitro culture of mucosal biopsies for 24 h with 3H N-acetyl mannosamine as a specific sialic acid precursor. Rectal biopsies were obtained at colonoscopy from patients with clinically inactive ulcerative colitis (n = 9) and controls (n = 12) who were patients found to have a normal colonoscopy performed for iron deficiency anaemia or altered bowel habit. The incorporation of 3H N-acetyl mannosamine into mucin was increased in ulcerative colitis (n = 9; 150; 113.3-393.2 dpm/micrograms mucin, median and interquartile ranges), compared with controls (n = 12; 33.6; 19.7-68.4 dpm/micrograms; p < 0.01). The ratio of incorporation into mucin of 3H N-acetyl mannosamine/14C N-acetyl galactosamine was also increased in ulcerative colitis (3.27; 1.93-4.98 dpm/dpm), compared with controls (1.35; 1.24-1.7 dpm/dpm; p < 0.001) suggesting that the increased incorporation of N-acetyl mannosamine probably reflects an increase in the average extent of sialylation per mucin oligosaccharide chain rather than an increase in the number of oligosaccharide chains. This increase in mucin sialylation seems unlikely to have a pathogenic role in the development of colitis but provides further evidence for the similarity between the alterations that occur in ulcerative colitis, colonic polyposis and malignancy.