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K A Papadakis

Publications and source records attributed to K A Papadakis.

At least 19 recordsLinked to original sources
PubMed2003

Infliximab in the treatment of medically refractory indeterminate colitis.

AIM: To examine the outcome of infliximab intervention in refractory indeterminate colitis. METHODS: Twenty patients with severe, medically refractory indeterminate colitis were treated with infliximab. All patients initially received infliximab, 5 mg/kg, intravenously and, in some patients, the dose was subsequently increased to 10 mg/kg. The number of infusions ranged from one to 16 per patient. Indeterminate colitis was defined as colitis that could not be classified with certainty as Crohn's disease or ulcerative colitis based on traditional clinical, endoscopic and histopathological criteria. The clinical response to infliximab was classified as complete response, partial response or non-response. RESULTS: Fourteen of the 20 patients (70%) showed a complete response to infliximab treatment, two showed a partial response and four showed no response. The four non-responders underwent colectomy with ileal pouch-anal anastomosis. The resected colon specimen was consistent with ulcerative colitis in all four cases, although two were subsequently re-classified as Crohn's disease. Eight additional patients were subsequently re-classified as having Crohn's disease on longer follow-up evaluation, whilst eight continued to have features of indeterminate colitis. The response rate to infliximab treatment was similar in both groups. CONCLUSIONS: Infliximab is effective in approximately two-thirds of patients with indeterminate colitis, and thus may be considered for patients with refractory disease prior to colectomy. The follow-up time afforded by infliximab treatment may allow for more accurate classification of the disease in a significant proportion of patients whose colitis has indeterminate features at initial presentation.

Adolescent↗
PubMed2001

CCR9-positive lymphocytes and thymus-expressed chemokine distinguish small bowel from colonic Crohn's disease.

BACKGROUND & AIMS: Thymus-expressed chemokine (TECK) or CCL25) is selectively expressed in the small bowel (SB), where lamina propria lymphocytes (LPL) and intraepithelial leukocyte expressing the cognate chemokine receptor CCR9 predominate. We characterize the role of TECK and CCR9-expresing lymphocytes in small intestinal Crohn's disease. METHODS: CCR9 expression on lymphocytes from lamina propria, mesenteric lymph node, and peripheral blood was analyzed by flow cytometry and by Northern blotting for LPL. TECK expression was analyzed in inflamed SB and colon by reverse-transcription polymerase chain reaction and immunohistochemistry. RESULTS: The fraction of CCR9(+) T cells in inflamed SB was significantly lower than in uninvolved SB mucosa. In contrast, in peripheral blood lymphocytes, CCR9(+) lymphocytes were markedly elevated in patients with small bowel Crohn's or celiac disease, but not in patients with purely colonic Crohn's. Also, TECK expression is altered in inflamed small bowel, being intensely expressed in a patchy distribution in crypt epithelial cells in proximity to lymphocytic infiltrates. TECK is not expressed in either normal or inflamed colon. CONCLUSIONS: In SB immune-mediated diseases, there is repartitioning of CCR9(+) lymphocytes between SB and blood and an altered pattern of TECK expression in SB Crohn's. The TECK/CCR9 ligand/receptor pair may play an important role in the pathogenesis of SB Crohn's disease.

Chemokines, CC↗
PubMed2001

Outcome of cytomegalovirus infections in patients with inflammatory bowel disease.

OBJECTIVE: The aim of this study was to determine the outcome of cytomegalovirus (CMV) infections complicating the course of inflammatory bowel disease (IBD). METHODS: The records and clinical courses were reviewed for all IBD patients who were evaluated at the IBD Center of the Cedars-Sinai Medical Center and who developed CMV infection. RESULTS: Ten patients with severe, medically refractory IBD (five ulcerative colitis, three Crohn's colitis, and two indeterminate colitis) developed CMV infection. All but two were hospitalized with exacerbation of their underlying disease and were receiving immunosuppressive treatment with steroids, thiopurines, and/or cyclosporine at the time CMV infection was recognized. Eight patients had documented colonic CMV (one had concurrent upper GI tract involvement), one developed interstitial CMV and Pneumocystis carinii pneumonia, and one developed primary CMV mononucleosis. Prompt treatment with ganciclovir and withdrawal of immunosuppressive treatment resulted in gradual improvement and induction of remission of the underlying IBD in five patients. The patient with concomitant CMV and P. carinii pneumonitis died. In two patients, treatment with ganciclovir did not alter the clinical course of their IBD, and one of them underwent colectomy. In one patient CMV was found on the resected colonic specimen. One patient with primary CMV infection responded also to ganciclovir treatment. CONCLUSIONS: CMV infection may aggravate the course of seemingly refractory IBD in patients who either fail to respond or experience worsening of symptoms despite immunosuppressive therapy. Expedient evaluation, prompt treatment intervention with ganciclovir, and withdrawal of immunosuppressive treatment may avoid complications and mortality. This regimen leads to improvement of the underlying IBD in most patients.

Adolescent↗
PubMed2000

The role of thymus-expressed chemokine and its receptor CCR9 on lymphocytes in the regional specialization of the mucosal immune system.

Chemokines play an important role in the migration of leukocytes at sites of inflammation, and some constitutively expressed chemokines may direct lymphocyte trafficking within lymphoid organs and peripheral tissues. Thymus-expressed chemokine (TECK or Ckbeta-15/CCL25), which signals through the chemokine receptor CCR9, is constitutively expressed in the thymus and small intestine but not colon, and chemoattracts a small fraction of PBLs that coexpress the integrin alpha(4)beta(7). Here we show that TECK is expressed in the human small bowel but not colon by endothelial cells and a subset of cells in intestinal crypts and lamina propria. CCR9 is expressed in the majority of freshly isolated small bowel lamina propria mononuclear cells (LPMC) and at significantly higher levels compared with colonic LPMC or PBL. TECK was selectively chemotactic for small bowel but not colonic LPMC in vitro. The TECK-induced chemotaxis was sensitive to pertussis toxin and partially inhibited by Abs to CCR9. TECK attracts predominantly the T cell fraction of small bowel LPMC, whereas sorted CD3(+)CCR9(+) and CD3(+)CCR9(-) lymphocytes produce similar Th1 or Th2 cytokines at the single cell level. Collectively, our data suggest that the selective expression of TECK in the small bowel underlie the homing of CCR9(+) intestinal memory T cells to the small bowel rather than to the colon. This regional specialization implies a segregation of small intestinal from colonic immune responses.

Cell Movement↗
PubMed2000

The role of chemokines and chemokine receptors in mucosal inflammation.

Chemokines represent a large family of small cytokines, the main function of which is the attraction of leukocytes to different tissues. Several chemokines and their receptors have been shown to play a critical role in lymphoid development, mucosal immunity, and inflammation. In this article we review recent advances in chemokine physiology and their potential role in the pathogenesis of mucosal inflammation. We also discuss the potential for the use of chemokine or chemokine receptor antagonists as novel therapies for inflammatory bowel disease.

Chemokines↗
PubMed2000

The clinical spectrum of stenotrophomonas (xanthomonas) maltophilia respiratory infection.

During a 15-month retrospective clinical study in an academic referral-based cancer center, 26 patients with S. maltophilia respiratory tract infections were identified (which were associated with bacteremia in 13 patients). Five of these 26 patients had previously undescribed sinopulmonary involvement. The infections were typically nosocomial. Nine patients with solid tumors had malignant involvement of the respiratory tract (five with obstruction). In two patients, the infection co-existed with pulmonary aspergillosis. Fifteen patients (58%) died of the infection. The factors that correlated with a poor outcome included bacteremic pneumonia, persistent neutropenia, presence of obstruction, development of septic shock or multiple organ dysfunction, and delay in institution of appropriate antibiotic therapy. In multivariate analysis, only septic shock and delayed therapy remained significant. Trimethoprim-sulfamethoxazole and/or ticarcillin-clavulanate were most commonly associated with a favorable outcome.

Journal Article↗
PubMed2000

Role of cytokines in the pathogenesis of inflammatory bowel disease.

Recent advances in the drug treatment of inflammatory bowel disease (IBD) have paralleled our understanding of the pathophysiology of ulcerative colitis and Crohn's disease. Several proinflammatory and immune-regulatory cytokines are upregulated in the mucosa of patients with IBD, and differences and similarities in the cytokine profiles of ulcerative colitis and Crohn's disease have been elucidated. Several clinical trials involving a chimeric anti-TNF-alpha (tumor necrosis factor-alpha) antibody have shown marked clinical benefit in the majority of patients with Crohn's disease, verifying the importance of TNF-alpha in the pathogenesis of Crohn's disease. In preliminary studies, treatment with recombinant human interleukin-10 has been beneficial in Crohn's disease but not in ulcerative colitis. Future treatment of IBD may include combination or sequential cytokine and anticytokine administration in defined groups of patients based on their mucosal cytokine profiles.

Animals↗
PubMed1999

Serologic testing in inflammatory bowel disease: its value in indeterminate colitis.

Serologic testing in inflammatory bowel disease provides a unique tool to classify these diseases into more homogeneous groups. Serum markers can also be used to identify common antigenic triggers and specific defects in mucosal immune regulation and cytokine imbalance in different parts of the gastrointestinal tract. ANCA (antineutrophil cytoplasmic antibodies) and ASCA (anti-Saccharomyces cerevisiae antibodies), the most extensively studied serologic markers, have been used to classify ulcerative colitis and Crohn's disease into such groups with certain phenotypic characteristics and responses to treatment. Similar studies have been initiated in indeterminate colitis, and these results will help in the future to define the immunopathogenesis, prognosis, and response to certain treatments in patients with this type of disease.

Animals↗
PubMed1999

An open-label pilot study of low-dose thalidomide in chronically active, steroid-dependent Crohn's disease.

BACKGROUND & AIMS: Thalidomide decreases production of tumor necrosis factor alpha, a proinflammatory cytokine associated with Crohn's disease (CD). In this study the safety, tolerance, and efficacy of low-dose thalidomide were evaluated for treatment of moderate-to-severe, steroid-dependent CD. METHODS: Twelve adult male patients with Crohn's Disease Activity Index (CDAI) scores of > or = 250 and < or = 500 despite > or = 20 mg prednisone/day were enrolled. The first 6 patients received 50 mg thalidomide every night, the next 6 received 100 mg every night. Steroid doses were stable during the first 4 weeks of treatment, then tapered during weeks 5-12. CDAI was used to assess response. RESULTS: (1) Disease activity improved consistently in all patients during weeks 1-4: 58% response, 17% remission. (2) Clinical improvement was generally maintained despite steroid taper during weeks 5-12. All patients were able to reduce steroids by >/=50%. Forty-four percent discontinued steroids entirely. In weeks 5-12, 70% of patients responded and 20% achieved remission. (3) Side effects were mild and mostly transient, with the most common being drowsiness, peripheral neuropathy, edema, and dermatitis. CONCLUSIONS: Low-dose thalidomide appears to be well tolerated and effective over a 12-week period. Results of this pilot study support the need for controlled multicenter trials of thalidomide for treatment of CD.

Adult↗
PubMed1999

Current theories on the causes of inflammatory bowel disease.

The understanding of the pathogenesis of CD and UC has greatly expanded over the last decade. The combination of abnormalities in the immune system, the contribution of nonimmune cells in the intestinal mucosa, a variety of genetic risk determinants, and random environmental factors may all be necessary to induce what clinically presents as IBD. It is likely that several agents can initiate an immune response that in the intestinal microenvironment and the genetic background of the patient finally leads to pathology.

Acute Disease↗
PubMed1997

Stenotrophomonas maltophilia meningitis. Report of two cases and review of the literature.

The authors report two cases of meningitis caused by Stenotrophomonas maltophilia in cancer patients following placement of an Ommaya reservoir for treatment of meningeal carcinomatosis. In addition, they review eight other cases of S. maltophilia that have been reported to date. Stenotrophomonas maltophilia meningitis is often associated with neurosurgical procedures; however, spontaneous infection may also occur, mainly in neonates. The disease's clinical presentation is similar to that of other forms of meningitis caused by Gram-negative bacilli. The overall mortality rate of this disease is 20% and is limited to neonates with spontaneous meningitis in whom effective antibiotic therapy is delayed. Meningitis caused by S. maltophilia in the modern era should be considered in immunocompromised hosts with significant central nervous system disease who have undergone neurosurgical procedures and who do not readily respond to broad-spectrum antimicrobial coverage.

Adult↗
PubMed1996

Stenotrophomonas (Xanthomonas) maltophilia urinary tract infection. A disease that is usually severe and complicated.

BACKGROUND: Stenotrophomonas (Xanthomonas) maltophilia has emerged as a causative agent of serious nosocomial infections. However, well-documented cases of urinary tract infection with this organism have rarely been reported. METHODS: review of the medical records of patients admitted to a large cancer center with cultures yielding S maltophilia from urinary sources during a 15-month period. RESULTS: All urinary tract infections were serious: 13 were complicated and two were acute uncomplicated pyelonephritis. The urinary tracts of 13 other patients were colonized with S maltophilia. Most of the colonized and infected patients were hospitalized with genitourinary malignancy, underwent urinary catheterization, and were receiving antibiotics inactive against S maltophilia. Neutropenia and urinary structural abnormalities were significantly associated with infection. The clinical course of infection was usually severe: fever (100%), sepsis disorder (47%), neutrophilia (70% of patients without neutropenia), bacteremia (13%) and death (7%). Still, response to treatment was prompt. CONCLUSIONS: Stenotrophomonas maltophilia urinary tract infection is usually associated with a severe clinical course. Risk factors for urinary colonization by this organism include hospitalization, urinary catheterization, and administration of inactive antibiotics. Risk factors for urinary tract infection include neutropenia and urinary structural abnormalities. In the presence of these risk factors, treatment of S maltophilia should be considered in patients with urinary colonization by the organism or in those with nosocomial urinary tract infection caused by an unknown pathogen and that is unresponsive to therapy with the antibiotics that are used to treat the common uropathogens.

Adolescent↗