Kazufumi Yamagata

Study for determination of the optimal cessation period of therapy with anti-platelet agents prior to invasive endoscopic procedures

BackgroundAnti-platelet agents are widely used for the treatment and prevention of thrombotic diseases. On the other hand, continuation of anti-platelet agents increases the risk of hemorrhagic complications in gastrointestinal endoscopy, and cessation of anti-platelet agents exposes the patient to the risk of thromboembolism. Only a few studies have actually studied the whether a cessation period is required prior to endoscopic procedures and if so, the optional duration of the period. The present study assessed the time course of primary hemostasis after the cessation of anti-platelet agents.MethodsEleven healthy men (age range, 19–29 years) were assigned to each of the following regimens: aspirin (ASA; 100 mg/day), ticlopidine (TP; 300 mg/day), and a combination of ASA (100 mg/day) and TP (300 mg/day) for 7 days. There was a washout period of more than 3 weeks between each regimen. A quantitative bleeding time test (QBT test) and platelet aggregation test were performed before the beginning of administration, on the last day of administration, and at 1, 3, and 5 days after cessation, and also at 7 days after cessation for the combination regimen.ResultsThe average bleeding time (BT) and total bleeding loss volume (Tv) of the 11 subjects after administration of the three regimens were significantly increased compared with those before administration. With the administration of ASA, increases of BT and Tv at 3 days after cessation were not significant. The Tv at 5 days after cessation of TP was not significantly increased. With the combination regimen, the BT and Tv at 7 days after cessation were not significantly increased.ConclusionsA 3-day cessation period for ASA, a 5-day cessation period for TP, and a 7-day cessation period for ASA + TP administration seem to be sufficient.

Aspirin effects on colonic mucosal bleeding

BACKGROUND: Many patients who require endoscopic treatments such as biopsy and polypectomy are given antiplatelet agents reluctantly. We have studied the effects of aspirin on colonic mucosal hemostasis. METHODS AND PATIENTS: We developed a new endoscopic device to make a standard incision (7-mm length) on the colonic mucosa to study colon bleeding time. We measured the colon bleeding time of normal colonic mucosa in 47 cases. The colon bleeding time and skin bleeding time (Simplate method) were measured before and one hour after aspirin ingestion (990 mg) in ten healthy subjects. RESULTS: The bleeding time of normal colonic mucosa was 156±71 (mean±standard deviation) seconds. Significant prolongation was noted in both skin bleeding time (357±192vs.477±183 seconds;P<0.05) and colon bleeding time (155±47vs.244±169 seconds;P<0.05) after aspirin ingestion. CONCLUSIONS: Bleeding time was measured safely under direct colonoscopic visualization. Aspirin prolonged the colon bleeding time. Therefore, endoscopists should be aware of a risk of abnormal bleeding after endoscopic biopsy and polypectomy in patients with aspirin use. Two days were necessary for colon bleeding time to become normalized in patients with aspirin use.

Retinoic acid-inducible gene-I is constitutively expressed and involved in IFN-γ-stimulated CXCL9-11 production in intestinal epithelial cells

Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH/D family proteins, and plays an important role in antiviral response via interferon-stimulated genes (ISGs) and type 1 IFN. In this study, the roles of RIG-I in the epithelial cells in the cross-talk between type 2 IFN and inducible chemokines production are high-lighted. The results showed that RIG-I was constitutively expressed in normal surface epithelia lining the colonic mucosa. RIG-I was constitutively expressed in the epithelial cell lines HT-29, and IFN-gamma and TNF-alpha enhanced the RIG-I expression in a dose-dependent manner. IFN-gamma was shown to stimulate CXCL9-11 production, and RNA interference against RIG-I resulted in significant decrease of IFN-gamma-induced CXCL9-11 productions. These results suggest that RIG-I play an important role in the cross-talk between inflammatory cytokines and immune cell trafficking. In conclusion, RIG-I might regulate the gut barrier function in homeostatic and inflammatory conditions.

Colonic intra-epithelial carcinoma occurring in a hyperplastic polyp via a serrated adenoma.

We present a case of intra‐epithelial carcinoma occurring in a serrated adenoma of the colon. The pedunculated polyp, which measured 12 × 10 × 6 mm, was endoscopically removed from the ascending colon of a 78‐year‐old woman. Histologically, the polyp mainly consisted of serrated adenomatous glands, and had foci of intra‐epithelial carcinoma at the top. Hyperplastic (metaplastic) areas were also present in both borders between the serrated adenomatous area and the surrounding normal mucosa. A sequential increase in the degree of dysplasia, and in the number of nuclei positively reactive for Ki‐67 and p53 was evident from the hyperplastic areas toward the foci of carcinoma. The polyp described here may represent a carcinogenic potential of hyperplastic polyp via serrated adenoma.

A quantitative immunohistochemical evaluation of inflammatory cells at the affected and unaffected sites of inflammatory bowel disease

Levels of T lymphocytes, histiocytes and mast cells have been reported to be increased in the affected mucosa of Crohns disease (CD) and ulcerative colitis (UC), but the colorectal distribution of these cells is not fully understood. We hypothesized that differences in cell densities between CD and UC would be characteristic, not only in the affected, but also in the unaffected mucosa. The aims of the present study were to clarify whether there were any differences in cell densities in CD, UC and infectious colitis (IC) in the affected mucosa and between CD and UC in the unaffected mucosa. Using mouse monoclonal antibodies recognizing memory T cells (OPD4), cytotoxic/suppressor T cells (C8/144B), histiocytes (PG‐M1) and mast cells (AA1), we evaluated mucosal cell densities in biopsy specimens from both endoscopically affected and unaffected sites of CD (n= 12) and UC (n= 15) and from affected sites of IC (n= 10). Ten normal controls were also examined. At affected sites, all cells were significantly more abundant in UC than in the other conditions, except that the density of PG‐M1+ in CD was similar to that seen in UC. Although the densities of OPD4+ and C8/144B+ cells at unaffected sites were slightly higher in both CD and UC and in UC, respectively, there was no significant difference in cell densities between CD and UC. The ratio of OPD4+ cell density at affected sites to that at unaffected sites was appreciably higher in UC than in CD. The results suggest that a common feature of UC and CD is an increase in PG‐M1+ cells at the affected mucosa but that the other inflammatory cells studied are more abundant, particularly in UC, and that the difference between UC and CD is conspicuous when comparing the OPD4+ cell density of the affected mucosa with that of the unaffected mucosa.

The Presentation of Haptenated Proteins and Activation of T Cells in the Mesenteric Lymph Nodes by Dendritic Cells in the TNBS Colitis Rat

Abstract: We described the role of dendritic cells (DCs) in aspects of T cell activation at the mesenteric lymph nodes (MLN) in trinitrobenzene sulfonic acid (TNBS)‐induced colitis. An antigenic‐immune response is induced at the MLN, and dendritic cells are the affected cell type. Cross‐linking and GRO/CINC‐1 have synergistic effects for DC maturation.

Transforming growth factor-β regulates susceptibility of epithelial apoptosis in murine model of colitis

Abstract: Transforming growth factor (TGF)‐beta has a key role in intestinal homeostasis. Our present data suggest that TGF‐beta, which was constitutively expressed by lamina propria mononuclear cells and epithelium, affected epithelial cells. Abnormal suppression of TGF‐beta could enhance the sensitivity of epithelial cells to apoptosis associated with interferon‐gamma in DSS‐induced colitis.

Macrophage Migration Inhibitory Factor and Activator Protein-1 in Ulcerative Colitis

Abstract: Macrophage migration inhibitory factor (MIF) is a cytokine that has potent antisteroid effects. We determined that MIF is involved in the glucocorticoid‐resistant inflammatory process of ulcerative colitis (UC), and the altered AP‐1 signal is a potent therapeutic target for refractory UC.

Existence of Variant γδT Cells in Crohn’s Disease

Background and Objectives: γδT cell populations are well-known for their unique distribution (e.g. intra-epithelial lymphocytes). Though their ligands play a major role in the immune response they have remained largely obscure. To shed light on this issue, we have analyzed in this study the complementarity determining region (CDR) 3 of the T cell receptor (TCR) Vδ2 chains. This provides an insight into the antigenic immune response in the intestinal mucosa in sickness and health. Methodology: Total RNA was extracted from surgically resected intestinal mucosa of patients with Crohn’s disease (CD) and controls. TCR Vδ2 cDNA was PCR-amplified using Vδ2 sense primer and Cδ antisense primer. The PCR products were then subcloned in pUC18 plasmid. From each sample, 20 subclones were randomly selected and subjected to nucleotide sequence analysis. Results: Sequence analysis revealed that the CDR3 sequences of the TCR Vδ2 chains were unique to each individual. The evidence also showed a significant restriction of the junctional diversity of the TCR Vδ2 chains while no such restriction was found for CD. Conclusions: The marked complexity of the TCR Vδ2 junctional sequences and the oligoclonality of the TCR Vδ2 genes in the control subjects are indicative of a positive selection and expansion of specific T cells in the normal, healthy condition. In CD patients, however, the expression of distinct, non-overlapping TCR Vδ2 clonotypes can be found, suggesting polyclonal activation of γδT cells in the diseased colon of CD patients. These findings have led us to conclude that accumulation of multiple γδT cell clonotypes may be involved in the pathogenesis of CD.