Building on existing tools to improve chronic disease prevention and screening in public health: a cluster randomized trial.

BACKGROUND: The BETTER (Building on Existing Tools to Improve Chronic Disease Prevention and Screening in Primary Care) intervention was designed to integrate the approach to chronic disease prevention and screening in primary care and demonstrated effective in a previous randomized trial. METHODS: We tested the effectiveness of the BETTER HEALTH intervention, a public health adaptation of BETTER, at improving participation in chronic disease prevention and screening actions for residents of low-income neighbourhoods in a cluster randomized trial, with ten low-income neighbourhoods in Durham Region Ontario randomized to immediate intervention vs. wait-list. The unit of analysis was the individual, and eligible participants were adults age 40-64 years residing in the neighbourhoods. Public health nurses trained as "prevention practitioners" held one prevention-focused visit with each participant. They provided participants with a tailored prevention prescription and supported them to set health-related goals. The primary outcome was a composite index: the number of evidence-based actions achieved at six months as a proportion of those for which participants were eligible at baseline. RESULTS: Of 126 participants (60 in immediate arm; 66 in wait-list arm), 125 were included in analyses (1 participant withdrew consent). In both arms, participants were eligible for a mean of 8.6 actions at baseline. At follow-up, participants in the immediate intervention arm met 64.5% of actions for which they were eligible versus 42.1% in the wait-list arm (rate ratio 1.53 [95% confidence interval 1.22-1.84]). CONCLUSION: Public health nurses using the BETTER HEALTH intervention led to a higher proportion of identified evidence-based prevention and screening actions achieved at six months for people living with socioeconomic disadvantage. TRIAL REGISTRATION: NCT03052959 , registered February 10, 2017.

Surgical outcomes and the impact of major surgery on quality of life, activity impairment and sexual health in hidradenitis suppurativa patients: a prospective single centre study.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic debilitating skin disease, frequently located in the groin and anogenital area, leading to a substantial impact on quality of life and sexual health in patients with HS. Skin-tissue-sparing excision with electrosurgical peeling (STEEP) is a procedure with known low recurrence rates and high patient satisfaction in retrospective series. However, a prospective study to investigate the impact of any major surgery on specific aspects of the quality of life has not yet been performed. OBJECTIVE: To assess surgical outcomes and the effect of major surgery on the general quality of life, sexual health and activity impairment in patients with HS. MATERIALS AND METHODS: A single centre prospective survey study was conducted among 40 patients undergoing major surgery. Surveys were completed prior to the surgery and 2, 6, 12 and 26 weeks after surgery. Besides the objective parameters (time to wound closure and surface of the wound), patient-reported outcomes were reported. RESULTS: Thirty-nine patients with a total of 171 survey responses were included for analysis. Patients with Hurley stage I or II had a shorter time to wound closure (TTWC) compared to patients with Hurley stage III (P = 0.005). TTWC was significantly prolonged in patients treated with biologics (P < 0.001). Smoking did not significantly influence TTWC. For patient-reported outcomes, DLQI and ASEX scores did not significantly improve during the study period of 6 months. However, activity and overall work impairment showed considerable improvement after surgery. CONCLUSION: Time to wound closure is significantly prolonged by higher Hurley stage and treatment with biologics, contrastingly not by smoking. Major surgery improved the overall work and daily activity impairment.

Surgery under general anaesthesia in severe hidradenitis suppurativa: a study of 363 primary operations in 113 patients.

BACKGROUND: Treatment of hidradenitis suppurativa (HS) is a difficult undertaking, especially as there is no consensus on what surgical technique is preferred. At our centre severe HS (Hurley II/III) is operated under general anaesthesia, mostly with the STEEP procedure. OBJECTIVES: To investigate characteristics, surgical outcomes and patient satisfaction of HS patients who underwent deroofing or STEEP under general anaesthesia. METHODS: A clinical records-based retrospective analysis was conducted of all patients who had surgery under general anaesthesia between 1999 and 2013. Patient satisfaction was retrospectively investigated with questionnaires. RESULTS: A total of 482 operations (363 primary operations and 119 re-operations) were performed during the study period. The proportion of women in the included population was 68%. The median diagnostic delay (patient's and doctor's delay) was 6.5 years. Relapses occurred after 29.2% of primary operations. Women had higher relapse rates than men [odds ratio 2.85 (1.07;7.61)]. Hypergranulation of the wound was the most common complication and occurred in 7% of all operations. The median score patients attributed to the medical effect of surgery was eight of 10 (zero corresponding to very dissatisfied and 10 to very satisfied). CONCLUSION: The diagnostic delay in HS is long due to a lack of knowledge in both patients and health care professionals, indicating that there is a need for education. Deroofing and the STEEP are effective surgical procedures in severe cases of HS and lead to a relatively high patient satisfaction. The postoperative relapse risk is higher in women. Prospective studies are required for the development of clear guidelines on the appropriate choice of surgery.

Low-dose rituximab is effective in pemphigus.

BACKGROUND: Rituximab, an anti-CD20 antibody, was shown in open series studies to be effective in treating pemphigus at a dose of 4 × 375 mgm(-2) as approved for B-cell malignancies. OBJECTIVES: We investigated whether a lower dose of rituximab is also effective for pemphigus. METHODS: Patients with pemphigus were treated with a single course of two infusions of rituximab (500 mg each) at an interval of 2 weeks. Clinical consensus late end points, B-cell number, desmoglein 1 and desmoglein 3 indices were monitored. RESULTS: We enrolled 15 patients in the study: three with pemphigus foliaceus (PF) and 12 with pemphigus vulgaris (PV). The follow-up was 32-152 weeks (median 94). All 15 patients responded to therapy. Eight patients achieved complete remission in a median period of 5 weeks (four on minimal therapy, four off therapy). Seven patients achieved partial remission in a median period of 34·5 weeks (five on minimal therapy, two off therapy). Relapses (40%) were seen between 53 and 103 weeks (median 97) after start of therapy. B-cell numbers dropped to <1% after first infusion, and remained undetectable in patients with sustained remission. The antidesmoglein 1 index correlated well with the clinical severity in PF, but this was less obvious in PV. CONCLUSIONS: A low dose of rituximab is an effective and safe treatment for pemphigus. Relapses may occur, mostly at the end of the second year. Cost-effectiveness studies with a long follow-up are required to determine the proper dosage of this expensive drug in pemphigus.

The anxiolytic effect of Bifidobacterium longum NCC3001 involves vagal pathways for gut-brain communication.

BACKGROUND: The probiotic Bifidobacterium longum NCC3001 normalizes anxiety-like behavior and hippocampal brain derived neurotrophic factor (BDNF) in mice with infectious colitis. Using a model of chemical colitis we test whether the anxiolytic effect of B. longum involves vagal integrity, and changes in neural cell function. Methods Mice received dextran sodium sulfate (DSS, 3%) in drinking water during three 1-week cycles. Bifidobacterium longum or placebo were gavaged daily during the last cycle. Some mice underwent subdiaphragmatic vagotomy. Behavior was assessed by step-down test, inflammation by myeloperoxidase (MPO) activity and histology. BDNF mRNA was measured in neuroblastoma SH-SY5Y cells after incubation with sera from B. longum- or placebo-treated mice. The effect of B. longum on myenteric neuron excitability was measured using intracellular microelectrodes. KEY RESULTS: Chronic colitis was associated with anxiety-like behavior, which was absent in previously vagotomized mice. B. longum normalized behavior but had no effect on MPO activity or histological scores. Its anxiolytic effect was absent in mice with established anxiety that were vagotomized before the third DSS cycle. B. longum metabolites did not affect BDNF mRNA expression in SH-SY5Y cells but decreased excitability of enteric neurons. CONCLUSIONS & INFERENCES: In this colitis model, anxiety-like behavior is vagally mediated. The anxiolytic effect of B. longum requires vagal integrity but does not involve gut immuno-modulation or production of BDNF by neuronal cells. As B. longum decreases excitability of enteric neurons, it may signal to the central nervous system by activating vagal pathways at the level of the enteric nervous system.

Igf1r+/CD34+ immature ICC are putative adult progenitor cells, identified ultrastructurally as fibroblast-like ICC in Ws/Ws rat colon.

The colon of Ws/Ws mutant rats shows impairment of pacemaker activity and altered inhibitory neurotransmission. The present study set out to find structural correlates to these findings to resolve mechanisms. In the colon of Ws/Ws rats, interstitial cells of Cajal associated with Auerbach's plexus (ICC-AP) were significantly decreased and ICC located at the submuscular plexus and intramuscular ICC were rarely observed based on immunohistochemistry and electron microscopy. Ultrastructural investigations revealed that there was no overall loss of all types of interstitial cells combined. Where loss of ICC was observed, a marked increase in fibroblast-like ICC (FL-ICC) was found at the level of AP. Immunoelectron microscopy proved FL-ICC to be c-Kit(-) but gap junction coupled to each other and to c-Kit(+) ICC; they were associated with enteric nerves and occupied space normally occupied by ICC in the wild-type rat colon, suggesting them to be immature ICC. In addition, a marked increase in immunoreactivity for insulin-like growth factor 1 receptor (Igf1r) occurred, co-localized with CD34 but not with c-Kit. A significantly higher number of Igf1r(+)/CD34(+) cells were found in Ws/Ws compared to wild-type rat colons. These CD34(+)/Igf1r(+) cells in the Ws/Ws colon occupied the same space as FL-ICC. Hence we propose that a subset of immature ICC (FL-ICC) consists of adult progenitor cells. Immunohistochemistry revealed a reduction of neurons positive for neuronal nitric oxide synthase. The functional capabilities of the immature ICC and the regenerative capabilities of the adult progenitor cells need further study. The morphological features described here show that the loss of pacemaker activity is not associated with failure to develop a network of interstitial cells around AP but a failure to develop this network into fully functional pacemaker cells. The reduction in nitrergic innervation associated with the Ws mutation may be the result of a reduction in nitrergic neurons.

Ultrastructural injury to interstitial cells of Cajal and communication with mast cells in Crohn's disease.

Crohn's disease associated dysmotility has been attributed to fibrosis and damage to enteric nerves but injury to interstitial cells of Cajal (ICC) could also be involved. We assessed ICC in specimens obtained from patients with Crohn's disease and determined the relation between ICC and the inflammatory infiltrate, particularly mast cells (MC) using quantitative immunohistochemistry and electron microscopy. Ultrastructural injury to ICC was patchy in all ICC subtypes but ICC-Auerbach's plexus (AP) showed damage more frequently, i.e. swelling of mitochondria, decreased electron density, autophagosomes and partial depletion of the cytoplasm. Light microscopy confirmed a significant decrease in c-kit immunoreactivity for ICC-AP and an increased number of MC in the muscularis externa. Electron microscopy showed MC exhibiting piecemeal degranulation and making frequent and selective membrane-to-membrane contact with all types of injured ICC which suggests chronic release of granule content to affect ICC. Extent of ICC injury was not associated with duration of the disease. In conclusion, ultrastructural injury and loss of ICC-AP is evident in Crohn's disease. Epidemiological and morphological data suggest that ICC have the capacity to regenerate in spite of the chronic insult. The muscularis hosts a marked number of MC that exhibit piecemeal degranulation associated with ICC and may facilitate ICC maintenance.

Pacemaker activity and inhibitory neurotransmission in the colon of Ws/Ws mutant rats.

The aim of this study was to characterize the pacemaker activity and inhibitory neurotransmission in the colon of Ws/Ws mutant rats, which harbor a mutation in the c-kit gene that affects development of interstitial cells of Cajal (ICC). In Ws/Ws rats, the density of KIT-positive cells was markedly reduced. Wild-type, but not Ws/Ws, rats showed low- and high-frequency cyclic depolarization that were associated with highly regular myogenic motor patterns at the same frequencies. In Ws/Ws rats, irregular patterns of action potentials triggered irregular muscle contractions occurring within a bandwidth of 10-20 cycles/min. Spontaneous activity of nitrergic nerves caused sustained inhibition of muscle activity in both wild-type (+/+) and Ws/Ws rats. Electrical field stimulation of enteric nerves, after blockade of cholinergic and adrenergic activity, elicited inhibition of mechanical activity and biphasic inhibitory junction potentials both in wild-type and Ws/Ws rats. Apamin-sensitive, likely purinergic, inhibitory innervation was not affected by loss of ICC. Variable presence of nitrergic innervation likely reflects the presence of direct nitrergic innervation to smooth muscle cells as well as indirect innervation via ICC. In summary, loss of ICC markedly affects pacemaker and motor activities of the rat colon. Inhibitory innervation is largely maintained but nitrergic innervation is reduced possibly related to the loss of ICC-mediated relaxation.

Interstitial cells of Cajal in health and disease. Part II: ICC and gastrointestinal stromal tumours.

Mesenchymal tumours in the gastrointestinal tract have long been problematic in terms of diagnosis, prognosis and therapy, but recent advances in immunohistochemistry and related therapies have allowed more specific diagnosis. In particular, the recognition that both the interstitial cells of Cajal (ICC) and many gastrointestinal stromal tumours (GISTs) are positive for c-kit and CD34 and have other features similar to those of ICC has led to the use of imatinib, a novel small molecule therapy that blocks the CD117/c-kit tyrosine kinase receptor, which shows remarkable efficacy in treatment of malignant and metastatic GISTs as well as other malignancies.

Low doses of ionizing radiation can prevent radiation-induced colonic epithelial hyporesponsiveness to muscarinic agonists.

PURPOSE: Colonic epithelium hyporesponsiveness to different secretagogues occurs after exposure to ionizing radiation, increasing susceptibility to bacterial translocation and intraluminal toxins. Growing evidence suggests that the biological effects of radiation might be hormetic in nature. We investigated if exposure to low doses of ionizing radiation (LDR) can prevent colon hyposecretion due to subsequent larger doses. METHODS: Rats were exposed to LDR (0.05 Gy) 24 h prior to 6 Gy, high dose radiation (HDR). The cyclic adenosine monophosphate (cAMP)-mediated pathway was explored using forskolin (FSK) and the intracellular Ca2+-mediated pathway through cholinergic stimulation. Changes in the colonic epithelium at the ultrastructural level were also explored. RESULTS: Maximal short circuit current (Isc) response to carbachol was significantly reduced in the group exposed to 6 Gy HDR and this was completely prevented by prior exposure to LDR. Responses to both FSK and electrical field stimulation (EFS) were significantly reduced after HDR but they were not prevented by prior adaption of LDR. Hyposecretion was not prevented by the inducible nitric oxide synthase (iNOS) inhibitor L-N6-(l-iminoethyl)lysine (L-NIL) ruling out a role for iNOS-derived nitric oxide (NO) in the colonic hyposecretion associated with whole body radiation. Prior exposure to LDR diminished the deleterious effect of full HDR on the ultrastructure of colonic epithelium as colonocytes vacuolization, microvilli lost and separation between neighboring cells were less evident. CONCLUSIONS: Previous exposure to LDR can prevent intracellular Ca2+-mediated colonic hyposecretion associated with exposure to HDR but fails to modify cAMP-mediated hyposecretion. Morphological damage at the ultrastructural level is less evident after prior LDR.

Intramuscular interstitial cells of Cajal associated with mast cells survive nitrergic nerves in achalasia.

Achalasia is dominated by injury to inhibitory nerves. As intramuscular interstitial cells of Cajal (ICC-IM) are proposed to form functional units with nitrergic nerves, their fate in achalasia may be critically important. We studied the relationship between loss of nitrergic nerves and injury to ICC-IM in patients with achalasia and determined associations between ICC-IM and mast cells (MC), using quantitative immunohistochemistry and electron microscopy. Loss of neuronal nitric oxide synthase (nNOS) immunoreactivity was completed within 3 years of acquiring achalasia. Thereafter, progressive ultrastructural injury to remaining nerve structures was evident. Within the first 2 years, the number of ICC-IM did not decline although ultrastructural injury was already present. Thereafter, loss of ICC-IM occurred unrelated to duration of disease. Damage to ICC-IM appeared unrelated to nerve injury. A significant MC infiltration was observed in the musculature; the number of MC was positively related to the persistent number of ICC-IM. Mast cell formed close contacts with ICC-IM and piecemeal-degranulation occurred towards ICC-IM. In conclusion, injury to ICC-IM in achalasia is variable, but not related to duration of disease and injury to nitrergic nerves. MC are prominent and form close functional contact with ICC-IM which may be responsible for their relatively long survival.

Characterization of depolarization-evoked ERG K currents in interstitial cells of Cajal.

Interstitial cells of Cajal (ICC) harbour the ether-a-go-go related gene (ERG) channel as shown by its characteristic rapidly deactivating current upon hyperpolarization. This property, however, does not explain the marked increase in cell excitability by ERG channel blockers, namely an increase in slow wave plateau duration and action potential generation. The objective of the present study was to characterize the depolarization-activated, E4031-sensitive ERG currents in murine ICC within a range of physiologically relevant membrane potentials. Whole cell currents were recorded from ICC isolated from murine neonatal jejunum, superfused with a physiological salt solution and with high intracellular Cs(+) to block most other K(+) currents. Upon depolarizing the cell from the resting membrane potential (approximately -60 mV) towards the region of the slow wave plateau (approximately -30 mV), significant sustained (window) current was generated between the potentials of -40 to 0 mV (maximal at -30 mV) and inhibited by the ERG specific blocker E4031. Channel activation followed by rapid inactivation produced a steady state conductance at -30 mV which was 51.6 +/- 11% of the hyperpolarization-evoked peak conductance value at -100 mV. When the cell repolarized from -30 mV, again, significant currents were generated, indicating recovery from inactivation, a typical characteristic of ERG channels. These data provide evidence that the ERG channel is of significance in the regulation of ICC excitability and provide the mechanism by which ERG channel blockade increases the slow wave duration.

Severe idiopathic gastroparesis due to neuronal and interstitial cells of Cajal degeneration: pathological findings and management.

Delayed gastric emptying can be due to muscular, neural, or humoral abnormalities. In the absence of an identified cause, gastroparesis is labelled as idiopathic. We present the case of a patient with severe idiopathic gastroparesis. Pharmacological approaches failed, as well as reduction in gastric emptying resistance with pyloric injection of botulinum toxin and pyloroplasty. Therefore, subtotal gastrectomy was performed. Histological and immunohistochemical study of the resected specimen showed hypoganglionosis, neuronal dysplasia, and a marked reduction in both myenteric and intramuscular interstitial cells of Cajal. To our knowledge, this is the first time these rare histological findings have been described in a patient with idiopathic gastroparesis.

Loss of CD117 (c-kit)- and CD34-positive ICC and associated CD34-positive fibroblasts defines a subpopulation of chronic intestinal pseudo-obstruction.

Chronic idiopathic intestinal pseudo-obstruction is a syndrome in which symptoms of intestinal obstruction are present in the absence of mechanical obstruction. Lack of normal pacemaker activity, usually generated by the interstitial cells of Cajal (ICC), could account for the apparent obstruction. ICC are normally located around and between the myenteric plexus ganglia and within muscle and also in the deep muscular plexus of the small bowel and the submuscular plexus of the large intestine, just within the circular muscle. ICC can be demonstrated immunohistochemically with CD117 (c-kit) as well as with CD34, although this is less specific. CD34 also stains a population of fibroblasts that are intimately associated with ICC. To determine whether there is a relative deficiency of ICC and CD34-positive fibroblasts in patients with chronic idiopathic intestinal pseudo-obstruction, tissue from 30 patients of large intestine and eight patients with small intestine pseudo-obstruction was obtained. Controls (large intestinal specimens from 12 patients, small intestinal specimens from six patients) were chosen from resections for Crohn's disease and colorectal neoplasia, both with and without dilatation. Examination of pseudo-obstruction cases identified 10 patients (nine large intestinal and one small intestinal) in which both CD117 and CD34 were absent or severely reduced in all three of the examined areas. In contrast, the control cases, including those with preobstructive dilatation, showed relatively constant ICC staining. These results suggest that there is a proportion of pseudo-obstruction cases in which the ICC are markedly reduced. These results also demonstrate that, in these cases, loss of the kit immunoreactivity is correlated with the loss of CD34 staining: this indicates that both the ICC and the CD34-positive fibroblasts associated with the ICC are absent. These findings will allow surgical pathologists to identify this subpopulation of patients with CIIP using tissue obtained by laparoscopic biopsy of the muscularis propria or surgical resection.

Mast cell-independent impairment of host defense and muscle contraction in T. spiralis-infected W/W(V) mice.

In response to nematode infection, the host presumably attempts to create an unfavorable environment to prevent larval penetration of the host and to expedite parasite expulsion from the gut. In this study, we have used W/W(V) mice with or without mast cells after bone marrow reconstitution (BMR-W/W(V)) to examine the role of mast cells in the host response. W/W(V), BMR-W/W(V), and wild-type (+/+) mice were infected with Trichinella spiralis. Infected W/W(V) mice exhibited less tissue damage and experienced a delay in worm expulsion and a greater degree of larval penetration of the gut leading to encystment in skeletal muscle. Tissue injury was greater and worm expulsion was normalized in BMR-W/W(V) mice, but larval penetration remained unchanged. Spontaneous contractile activity of jejunal muscle was disrupted in W/W(V) mice, as was the contractile response to carbachol. These abnormalities were also present in BMR-W/W(V) mice. These results indicate that mast cells mediate tissue damage and contribute to the timely expulsion of nematodes from the gut during primary infection.

Muscarinic activation of transient inward current and contraction in canine colon circular smooth muscle cells.

Muscarinic receptor mediated membrane currents and contractions were studied in isolated canine colon circular smooth muscle cells. Carbachol (10(-5) M) evoked a slow transient inward current that was superimposed by a transient outward current at holding potentials greater than -50 mV. Carbachol contracted the cells by 70 +/- 2%. The effects of carbachol were blocked by atropine (10(-6) M), tetraethyl ammonium (20 mM), and BAPTA-AM (25 mM applied for 20 min). The inward current and contraction were not sensitive to diltiazem (10(-5) M), nitrendipine (3 x 10(-7) M), niflumic acid (10(-5) M), or N-phenylanthranilic acid (10(-4) M), but were gradually inhibited after repetitive stimulations in Ca2+ free solution. Ni2+ (2 mM) inhibited the inward current by 67 +/- 4%. The inward current reversed at +15 mV. The outward component could be selectively inhibited by iberiotoxin (20 nM) or by intracellular Cs+. Repeated stimulation in the presence of cyclopiazonic acid (CPA, 3 microM) inhibited the carbachol-induced outward current and partially inhibited contraction. CPA did not inhibit the inward current. In conclusion, muscarinic receptor stimulation evoked a CPA-sensitive calcium release that caused contraction and a CPA-insensitive transient inward current was activated that is primarily carried by Ca2+ ions and is sensitive to Ni2+.

Regulation of slow wave frequency by IP(3)-sensitive calcium release in the murine small intestine.

Slow waves determine frequency and propagation characteristics of contractions in the small intestine, yet little is known about mechanisms of slow wave regulation. We propose a role for intracellular Ca(2+), inositol 1,4,5,-trisphosphate (IP(3))-sensitive Ca(2+) release, and sarcoplasmic reticulum (SR) Ca(2+) content in the regulation of slow wave frequency because 1) 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM, a cytosolic Ca(2+) chelator, reduced the frequency or abolished the slow waves; 2) thapsigargin and cyclopiazonic acid (CPA), inhibitors of SR Ca(2+)-ATPase, decreased slow wave frequency; 3) xestospongin C, a reversible, membrane-permeable blocker of IP(3)-induced Ca(2+) release, abolished slow wave activity; 4) caffeine and phospholipase C inhibitors (U-73122, neomycin, and 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate) inhibited slow wave frequency; 5) in the presence of CPA or thapsigargin, stimulation of IP(3) synthesis with carbachol, norepinephrine, or phenylephrine acting on alpha(1)-adrenoceptors initially increased slow wave frequency but thereafter increased the rate of frequency decline, 6) thimerosal, a sensitizing agent of IP(3) receptors increased slow wave frequency, and 7) ryanodine, a selective modulator of Ca(2+)-induced Ca(2+) release, had no effect on slow wave frequency. In summary, these data are consistent with a role of IP(3)-sensitive Ca(2+) release and the rate of SR Ca(2+) refilling in regulation of intestinal slow wave frequency.

Gastrointestinal stromal tumors may originate from a subset of CD34-positive interstitial cells of Cajal.

Most gastrointestinal stromal tumors (GISTs), a subgroup of mesenchymal neoplasms of the gut wall, express both Kit (CD117) and CD34 proteins. It has been suggested that GISTs originate from or differentiate into interstitial cells of Cajal (ICC), after several reports indicated that ICC are likely the only cells in the gut which express both Kit and CD34. ICC are among the few cell types resident in the gut which express Kit, together with mast cells. However, the question whether or not ICC express CD34 is currently disputed. Using single-cell reverse transcriptase-polymerase chain reaction (RT-PCR) on cultured murine intestinal cells, single ICC were selected by morphology and tested for the expression of c-kit and CD34 mRNA. Most ICC were only c-kit-positive, however a subset (7 out of 43) were double positive for both c-kit and CD34. In the human small intestine, sequential immunohistochemical staining for Kit and CD34 proteins on the same 3-microm sections showed that some of the ICC surrounding Auerbach's plexus and ICC within the circular muscle layer of the small intestine were positive for both Kit and CD34. In addition, CD34(+)Kit(-) cells were seen adjacent to ICC. These data from two different techniques indicate that ICC can be double positive for Kit and CD34. Thus, GISTs with the Kit(+)CD34(+) phenotype may arise from a subpopulation of CD34(+) Kit(+) ICC.

Structural relationships between immune cells and longitudinal muscle during a Trichinella spiralis infection in the rat intestine.

A Trichinella spiralis infection produces an acute inflammatory reaction and tissue damage in the mucosa, and, in addition, functional changes occur in the external muscle layers. The aim of the present study was to characterize structural changes in the musculature that occur during early infection, and to identify relationships between immune cells and muscle cells, as part of an ongoing investigation into the immune modulation of motor function in the gut. Rats were infected with T. spiralis larvae and the gut fixed at 12 h, 24 h, 48 h and 6 days post-infection for electron microscopy of the longitudinal muscle. Macrophages and lymphocytes penetrated the longitudinal musculature 12-24 h post-infection. Distinct contacts were observed between specific cell types; cellular protrusions from macrophages or lymphocytes made close apposition contacts with smooth muscle cells. Resident macrophages in the subserosal space, fibroblast-like cells as well as smooth muscle cells showed marked activation during inflammation. Fibroblast-like cells were frequently seen intercalated between lymphocytes and smooth muscle cells, hence they may mediate communication between immune cells and the musculature.

Interstitial cells of Cajal as precursors of gastrointestinal stromal tumors.

Interstitial cells of Cajal (ICC) are implicated in the regulation of gut peristalsis and are immunostained by antibodies against Kit (CD117), a tyrosine kinase receptor. Most gastrointestinal mesenchymal tumors (GIMTs) are of uncertain histogenesis, although many are CD34-positive. CD34 was found to colocalize with vimentin (Vim) and the Kit-positive networks of cells within and around neural plexi, indicating that ICC can be Vim- and CD34-positive. ICCs appear to be the only Kit+CD34+Vim+ cell in the gut. Formalin-fixed, paraffin-embedded tissues from 43 GIMTs were immunostained for Kit, CD34, Vim, PGP 9.5 (PGP, a neural marker), muscle-specific actin (MSA), and other markers including desmin (Des). Eight tumors were myoid (MSA+Des+Vim-Kit-CD34-), and one was a schwannoma (PGP+S100+Vim+Kit-CD34-), but 34 tumors were of uncertain histogenesis (gastrointestinal stromal tumors, GIST), exhibiting neither a complete myoid nor a schwannian immunophenotype. All 34 were Vim+, and 33/34 were either Kit (n = 30) or CD34 (n = 23) immunoreactive. Of these 34 GIST, 24 were negative for all myoid and neural markers, 6 were PGP+S100-, and 4 were MSA+Des-. The Kit+CD34+Vim+ immunophenotype of GIST suggests that they originate from, or have differentiated into, ICC-like cells; the term ICC tumor (ICCT) is suggested. Kit is a more sensitive marker than CD34 for ICCT, but both are required in tumor identification. All clinically malignant GISTs were pathologically malignant (size, mitoses) but also showed loss of either CD34 or Kit. "Blind" examination of electron micrographs in 10 tumors showed them to be heterogeneous. Some had features seen in normal ICC, but cells could not be positively identified as being adult ICC. GIMT may therefore be classifiable into those with pure myoid, schwannian (or neural) differentiation, but the majority are of ICC origin or show ICC differentiation immunophenotypically (ICCT).