Inflammatory bowel disease (IBD) arises from a dysregulated mucosal immune response to luminal bacteria. Toll-like receptor (TLR)4 recognizes LPS and transduces a proinflammatory signal through the adapter molecule myeloid differentiation marker 88 (MyD88). We hypothesized that TLR4 participates in the innate immune response to luminal bacteria and the development of colitis. TLR4-/- and MyD88-/- mice and littermate controls were given 2.5% dextran sodium sulfate (DSS) for 5 or 7 days followed by a 7-day recovery. Colitis was assessed by weight loss, rectal bleeding, and histopathology. Immunostaining was performed for macrophage markers, chemokine expression, and cell proliferation markers. DSS treatment of TLR4-/- mice was associated with striking reduction in acute inflammatory cells compared with wild-type mice despite similar degrees of epithelial injury. TLR4-/- mice experienced earlier and more severe bleeding than control mice. Similar results were seen with MyD88-/- mice, suggesting that this is the dominant downstream pathway. Mesenteric lymph nodes from TLR4-/- and MyD88-/- mice more frequently grew gram-negative bacteria. Altered neutrophil recruitment was due to diminished macrophage inflammatory protein-2 expression by lamina propria macrophages in TLR4-/- and MyD88-/- mice. The similarity in crypt epithelial damage between TLR4-/- or MyD88-/- and wild-type mice was seen despite decreased epithelial proliferation in knockout mice. TLR4 through the adapter molecule MyD88 is important in intestinal response to injury and in limiting bacterial translocation. Despite the diversity of luminal bacteria, other TLRs do not substitute for the role of TLR4 in this acute colitis model. A defective innate immune response may result in diminished bacterial clearance and ultimately dysregulated response to normal flora.

BACKGROUND AND AIMS: Considerable difficulties persist amongst pathologists in agreeing on the presence and severity of gastric atrophy. An international group of pathologists pursued the following aims: (i) to generate an acceptable definition and a simple reproducible classification of gastric atrophy; and (ii) to develop guidelines for the recognition of atrophy useful for increasing agreement among observers.\ud \ud METHODS: After redefining atrophy as the 'loss of appropriate glands' and examining histological samples from different gastric compartments, three categories were identified: (i) negative; (ii) indefinite; (iii) atrophy, with and without intestinalization. Atrophy was graded on a three-level scale. Interobserver reproducibility of the classification was tested by kappa statistics (general and weighted) in a series of 48 cases.\ud \ud RESULTS: The medians of the general agreement and weighted kappa values were 0.78 and 0.73, respectively. The weighted kappa coefficients, obtained by cross-tabulating the evaluation of each pathologist against all others, were, with only one exception, > 0.4 (moderate to excellent agreement).\ud \ud CONCLUSIONS: By using the definition of atrophy as the loss of appropriate glands and distinguishing the two main morphological entities of metaplastic and non-metaplastic types, a high level of agreement was achieved by a group of gastrointestinal pathologists trained in different cultural contexts

Cell proliferation and apoptosis in kidneys with chronic obstructive uropathy (COU) have not been adequately studied. Whether these fundamental cellular processes play any role in the pathogenesis and evolution of COU remains undetermined. Sprague-Dawley rats with COU induced by unilateral ureteral ligation were sacrificed at postoperative days 1, 6, 9, 15, 34, 43, 60, 75, and 90, and were compared with control, sham-operated rats sacrificed at days 0, 15, 43, and 90. The kidneys with ureteral ligation, the contralateral kidneys, and the control kidneys were submitted to in situ end-labeling of fragmented DNAs for the detection of apoptotic cells, and to immunostaining with many monoclonal antibodies directed against the nuclear antigens associated with cell proliferation for the detection of proliferating cells. Additional rats with COU were also submitted to BrdU labeling to detect proliferating cells. The tubular, interstitial, and glomerular cells showing either apoptosis or proliferation were separately quantitated and the obtained data were correlated with dry kidney weight, tubular diameter, glomerular surface area and interstitial volume. Apoptotic tubular cells in kidney with COU increased rapidly, reaching 30-fold that of control at day 25, which was followed by an equally rapid decrease to the control level. During the same period, both the dry kidney weight and the mean tubular diameter decreased markedly. These data suggest that apoptosis may play a significant role in tubular atrophy and renal weight loss. The rapid increase in tubular cell apoptosis was immediately preceded by a 37% gain in the dry kidney weight over the control; just before that increase, there was also an approximate 60-fold increase in the proliferation rate of tubular cells detected by immunostaining for proliferating nuclear antigen or by BrdU labeling. The significance of this intriguing temporal relationship of tubular cell apoptosis and proliferation remains to be elucidated, but it may have pathogenetic implications. In contrast to the rise and fall of the frequency of tubular cell apoptosis and proliferation, the frequency of interstitial cell apoptosis and proliferation displayed continuous increase toward the end of the experiment, with a roughly parallel increase in the interstitial damage. Apoptosis and proliferation of glomerular cells in kidneys with COU did not show any significant changes throughout the experiment. In conclusion, the obtained data suggest that tubular cell apoptosis may be pathogenetically related to the tubular atrophy and renal tissue loss in COU, and that proliferation and apoptosis of interstitial cells may play a role in the observed interstitial changes in this model. This study should provide the impetus for further exploration of the mechanisms of cell death and cell proliferation as a novel venue for understanding the pathogenesis of COU.

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The anti-TNF-alpha antibody infliximab (Remicade) is highly effective in the treatment of Crohn's disease. A subset of patients experience allergic reactions as a result of antibodies to infliximab (ATIs). The purpose of the current study is to describe the safety and efficacy of adalimumab (Humira) in patients previously allergic or intolerant to infliximab. Adalimumab is an anti-TNF-alpha agent containing only human peptide sequences. Seven patients have been treated with adalimumab who had experienced immediate- or delayed-hypersensitivity reactions to infliximab and one with infliximab-induced lupus. Except for injection site discomfort, adalimumab was well tolerated without signs or symptoms of allergic reactions. One patient who had previously received pooled human immunoglobulin developed a pruritic rash after each dose of adalimumab. Patients with active disease who had previously experienced a robust response to infliximab responded to adalimumab as reflected by an improvement in Harvey-Bradshaw index and inflammatory markers. Based on these preliminary data, adalimumab may be a safe and effective substitute for infliximab-allergic patients. Individuals who have been exposed to human antibodies may be sensitized to other human antibodies such as adalimumab.

Thirty-one paragangliomas of the cauda equina region were studied (18 men and 13 women, ages 30-71 years [mean, 51 years]). Symptoms (1 day to 15 years in duration; mean, 48 months) included low back pain (87%), sensory/motor deficits (35%), urinary/fecal incontinence (13%), and paraplegia (6%). All patients studied had some myelographic block. Cerebrospinal fluid protein level ranged from 56 to 7000 mg/dl (mean, 1109 mg/dl). Most tumors were limited to the filum terminale, although one also involved the conus medullaris and two clearly arose from a caudal nerve root. All but one were entirely intradural. The tumor was totally excised in 26 cases; these patients remain disease-free. Of three patients whose tumors were excised subtotally, two received radiotherapy; the one non-radiated patient died of tumor-related complications. No autopsy was performed. One partially encapsulated tumor that had been subjected to biopsy and irradiation presented 1 year later with osseous invasion and retroperitoneal extension; 20 years after subtotal excision, this patient is alive but paraplegic. Morphologically, all tumors resembled paraganglioma at other sites. Cytologic atypia and mitotic activity generally were absent to mild. Fourteen (45%) cases showed ganglionic differentiation. All tumors tested were immunoreactive for neuron-specific enolase and neurofilament protein, and most showed somatostatin or serotonin reactivity. S-100 protein immunoreactivity was noted in sustentacular cells and, to a lesser extent, within chief cells and neurons. The authors conclude that paragangliomas are largely benign and encapsulated and respond to simple resection. When surgically feasible, gross total removal should be the goal of surgery. When subtotal resection is necessary or when local invasion leaves a question as to completeness of tumor removal, irradiation seems mandatory although far from guaranteeing prevention of recurrence. Biopsy alone is undesirable.

The clinicopathologic features of 11 cases (8 in men) of duodenal gangliocytic paraganglioma are presented. The patients averaged 56 years of age; none showed evidence of phakomatosis. Ten tumors occurred in the second portion of the duodenum, and one arose in the third portion. All tumors were polypoid, and half presented with gastrointestinal bleeding. The neoplasms were composed of paraganglioma and carcinoid-like elements, neurons, and Schwann as well as sustentacular cells. All tumors behaved in a benign fashion after local resection or snare polypectomy; long-term follow-up (1-25 years; mean, 8.3 years) showed no recurrence in any case. Immunocytochemical examination demonstrated the presence of somatostatin, serotonin, and human pancreatic polypeptide within endocrine cells and neurons.

P16 is a tumor suppressor gene product, shown to be overexpressed in most cervical carcinomas and dysplasias associated with high-risk human papilloma virus (HPV) infection. HPV is also associated with anal squamous dysplasias and carcinomas. Significant interobserver and intraobserver variation exists in the interpretation of biopsies for anal intraepithelial neoplasia (AIN). This study was undertaken to assess the potential role of p16 and Ki67 immunohistochemical expression in refining the diagnosis and grading of AIN.One-hundred and four anal biopsies from 74 patients were retrieved from the surgical pathology files of the department. After discrepancies were resolved and concurrence was achieved by at least 2 of 3 reviewing pathologists, the diagnoses were as follows: 37 negative, 12 condylomas without overt dysplasia, 14 AIN I, 25 AIN II, and 16 AIN III. p16 and Ki67 expression was evaluated by ABC immunoperoxidase staining whereas the presence of the high-risk subtypes of HPV virus was determined by in situ hybridization on a subset of the biopsies. Results were reviewed by 2 pathologists and positive and negative staining was correlated with H&E diagnoses. Nuclear and/or nuclear and cytoplasmic staining was considered as positive for p16 when present in >10% of squamous cells. Two patterns of positive p16 staining were observed: (1) "spotty" in which positive cells were scattered throughout the lesion and (2) "band" in which >90% of contiguous cells in the lesion stained positive. A band-like pattern of p16 immunoreactivity was seen in 21.4% AIN I, 80% AIN II, and 87.5% AIN III cases. None of the condylomas and only 1 of the negative cases showed a band of p16 positive staining. Spotty p16 immunoreactivity was observed in 8.1% negative, 8.3% condyloma, 14.3% AIN I, 12.0% AIN II, and 12.5% AIN III cases. More than 50% of nuclei stained positive for Ki67 in 28.6% AIN I, 48.0% AIN II, and 75.0% AIN III cases but in none of the negative or condyloma cases. On the basis of these results, a band-like pattern of p16 staining and Ki67 positivity in >50% of the squamous cell nuclei were strongly associated with high-grade AIN. Conversely, absence of a p16 band of positivity coupled with Ki67 positivity in <50% of nuclei was frequently associated with benign lesions. Band like p16 staining also correlated strongly with the presence of high-risk HPV. Most AIN I lesions stained similar to the nondysplastic cases. A small subset of biopsies studied did not conform to the pattern described above: 4 of 14 (28.6%) AIN I lesions showed a band-like pattern of p16 staining and/or >50% Ki67 positive nuclei. Two of these cases were positive for high-risk HPV DNA. 4 of 25 (16.0%) AIN II lesions comprising 9.8% of the 41 high-grade AINs (AIN II and III) showed spotty p16 positivity and <50% Ki67 positive nuclei. One was positive for high-risk HPV DNA. We conclude that when used together and evaluated in conjunction with H&E stained sections, p16 and Ki67 immunoexpression is a useful adjunct in the diagnosis and grading of AIN.