Predictors of combat training attrition in Israel Defense Forces soldiers.

BACKGROUND: Attrition from combat service carries significant organizational and personal ramifications, but predicting factors associated with attrition remains challenging. AIMS: To evaluate medical and psychosocial factors associated with attrition from basic combat training (BCT) in the Israel Defense Forces (IDF). In addition, we identify subsets of the recruit population which exhibit certain trends in terms of medical corresponding with a high risk of attrition. METHODS: A cross-sectional study of IDF combat trainees undergoing infantry BCT between 2012 and 2017. Data were collected from the soldiers' electronic medical and administrative records. We used multivariable logistic regression and the SAS® decision-tree tool to analyse key predictive factors for attrition. RESULTS: A total of 46 472 soldiers enlisted to BCT during the research period. The mean body mass index (BMI) was 21.8 (SD 3.54). The overall attrition rate was 10%. The following factors were associated with attrition from BCT: ethnicity (P < 0.01), BMI (P < 0.01), pre-enlisting motivation score (P < 0.01) and the number of mental health officer visits (P < 0.01). Using a decision-tree model, we found a high attrition rate among soldiers who had >5.2 to primary care physician visits (11% attrition rate versus 3%) or more than 11 sick leave days (59% versus 19%). CONCLUSIONS: This study sheds light on unique measures relating to attrition. Attrition is associated with several demographic and psychosocial factors. Early prediction of motivation and monitoring of healthcare utilization may enable early identification and focused interventions targeting soldiers at high risk for attrition. These findings need to be further translated into actionable directives and further investigations.

Importance and regulation of the colonic mucus barrier in a mouse model of colitis.

The colonic mucus layer serves as an important barrier and prevents colonic bacteria from invading the mucosa and cause inflammation. The regulation of colonic mucus secretion is poorly understood. The aim of this study was to investigate the role of the mucus barrier in induction of colitis. Furthermore, regulation of mucus secretion by luminal bacterial products was studied. The colon of anesthetized Muc2(-/-), Muc1(-/-), wild-type (wt), and germ-free mice was exteriorized, the mucosal surface was visualized, and mucus thickness was measured with micropipettes. Colitis was induced by DSS (dextran sodium sulfate, 3%, in drinking water), and disease activity index (DAI) was assessed daily. The colonic mucosa of germ-free and conventionally housed mice was exposed to the bacterial products LPS (lipopolysaccharide) and PGN (peptidoglycan). After DSS induction of colitis, the thickness of the firmly adherent mucus layer was significantly thinner after 5 days and onward, which paralleled the increment of DAI. Muc2(-/-) mice, which lacked firmly adherent mucus, were predisposed to colitis, whereas Muc1(-/-) mice were protected with significantly lower DAI by DSS compared with wt mice. The mucus barrier increased in Muc1(-/-) mice in response to DSS, whereas significantly fewer T cells were recruited to the inflamed colon. Mice housed under germ-free conditions had an extremely thin adherent colonic mucus layer, but when exposed to bacterial products (PGN or LPS) the thickness of the adherent mucus layer was quickly restored to levels observed in conventionally housed mice. This study demonstrates a correlation between decreasing mucus barrier and increasing clinical symptoms during onset of colitis. Mice lacking colonic mucus (Muc2(-/-)) were hypersensitive to DSS-induced colitis, whereas Muc1(-/-) were protected, probably through the ability to increase the mucus barrier but also by decreased T cell recruitment to the afflicted site. Furthermore, the ability of bacteria to regulate the thickness of the colonic mucus was demonstrated.

Abnormal heart rate regulation in GIRK4 knockout mice.

Acetylcholine (ACh) released from the stimulated vagus nerve decreases heart rate via modulation of several types of ion channels expressed in cardiac pacemaker cells. Although the muscarinic-gated potassium channel I(KACh) has been implicated in vagally mediated heart rate regulation, questions concerning the extent of its contribution have remained unanswered. To assess the role of I(KACh) in heart rate regulation in vivo, we generated a mouse line deficient in I(KACh) by targeted disruption of the gene coding for GIRK4, one of the channel subunits. We analyzed heart rate and heart rate variability at rest and after pharmacological manipulation in unrestrained conscious mice using electrocardiogram (ECG) telemetry. We found that I(KACh) mediated approximately half of the negative chronotropic effects of vagal stimulation and adenosine on heart rate. In addition, this study indicates that I(KACh) is necessary for the fast fluctuations in heart rate responsible for beat-to-beat control of heart activity, both at rest and after vagal stimulation. Interestingly, noncholinergic systems also appear to modulate heart activity through I(KACh). Thus, I(KACh) is critical for effective heart rate regulation in mice.

Cystic fibrosis mice lacking Muc1 have reduced amounts of intestinal mucus.

Normally a thin layer of mucus covers the surface of the gastrointestinal tract protecting the epithelial cells from their environment. In cystic fibrosis (CF), mucus accumulation is abnormally high, resulting in severe intestinal obstruction. The major structural components of mucus are large mucin glycoproteins. We determined specific mucin RNA and protein expression in the gastrointestinal tract of inbred CF transmembrane conductance regulator (CFTR) knockout (CF) mice and correlated expression with histological analyses of tissues. Mucins were detected histochemically using general carbohydrate stains and specific mucin antibodies. Mucin RNA levels were determined by reverse transcription-PCR. Comparisons were made between CF mice and control siblings, all maintained on a liquid diet after weaning. Analyses of the mucins Muc2, Muc3, and Muc5ac showed lower levels of RNA expression in the CF mice and similar levels of protein. Significantly, there was a sixfold increase in Muc1 RNA expression in the colon of the CF mouse and a moderate increase in Muc1 protein. Further, CF mice lacking Muc1 exhibited greatly diminished intestinal mucus obstruction when compared with Muc1- expressing CF mice and had better survival on solid food. We suggest that Muc1 plays an important role in the mucus obstructions observed in the gastrointestinal tract of the CFTR knockout mouse.

MUC1 (CD227) interacts with lck tyrosine kinase in Jurkat lymphoma cells and normal T cells.

MUC1 (CD227) is a large transmembrane epithelial mucin glycoprotein, which is aberrantly overexpressed in most adenocarcinomas and is a target for immune therapy for epithelial tumors. Recently, MUC1 has been detected in a variety of hematopoietic cell malignancies including T and B cell lymphomas and myelomas; however, its function in these cells is not clearly defined. Using the Jurkat T cell lymphoma cell line and normal human T cells, we demonstrate that MUC1 is not only expressed in these cells but is also phosphorylated upon T cell receptor (TCR) ligation and associates with the Src-related T cell tyrosine kinase, p56lck. Upon TCR-mediated activation of Jurkat cells, MUC1 is found in the low-density membrane fractions, where linker of T cell activation is contained. Abrogation of MUC1 expression in Jurkat cells by MUC1-specific small interfering RNA resulted in defects in TCR-mediated downstream signaling events associated with T cell activation. These include reduction in Ca2+ influx and extracellular signal-regulated kinase 1/2 phosphorylation, leading to a decrease in CD69 expression, proliferation, and interleukin-2 production. These results suggest a regulatory role of MUC1 in modulating proximal signal transduction events through its interaction with proteins of the activation complex.

Genetic modulation of neu proto-oncogene-induced mammary tumorigenesis.

Modulation of oncogene-induced carcinogenesis by secondary mutation or genetic background may be an important factor in determining the expression of the tumor phenotype. We have investigated the role of loss of function mutations and strain-specific genetic elements in the modulation of oncogene-induced breast cancer using a murine model. FVB female mice transgenic for the rat neu proto-oncogene [mouse mammary tumor virus (MMTV)-neu] developed mammary tumors between 7 and 12 months of age, whereas FVB x C57Bl/6 (F1) MMTV-neu mice had tumor latencies greater than 18 months. The expression level of the neu transgene was equivalent in tumor tissue from both FVB and F1 mice. Furthermore, increased tumor latency did not appear to be associated with a decrease in expression of the neu transgene in the normal mammary gland of F1 mice because immunohistochemical staining for neu expression in the mammary glands of 3-month-old virgin female mice revealed similar levels of protein expression in FVB and F1 animals. When F1 animals were backcrossed one generation onto the FVB strain ([FVB x B6] F1 x FVB), a subset of the resulting offspring developed tumors with a latency equivalent to that of the pure-strain FVB mice. Statistical analysis of the genetic variability in mammary tumor latency indicated that approximately three independent genes were involved in the latency effect. Interestingly, when tumor growth rates were compared in these same animals, F1 mice had significantly faster tumor growth rates compared with FVB mice.

Synthesis of alpha 1-antichymotrypsin and alpha 1-acid glycoprotein by human breast epithelial cells.

Malignant and uninvolved human breast tissues were maintained in organ culture for 3 to 6 days. Under these conditions, the three-dimensional glandular architecture is maintained with the least disruption of tissue integrity. The biosynthesis and release of glycoproteins were studied by using the incorporation of [14C]glucosamine and [14C]leucine by the breast surgical specimens. Five major families of labeled glycoproteins were identified from culture supernatants using two-dimensional gel electrophoresis. Quantitative immunoprecipitation established that 16 to 30% of the total of labeled glycoproteins were recognized as normal serum components. Two of these glycoproteins were antigenically related to normal human serum components as demonstrated with crossed immunoelectrophoresis. Evidence was obtained for the active synthesis of alpha 1-antichymotrypsin and alpha 1-acid glycoprotein by human breast epithelial cells. alpha 1-Antichymotrypsin accounted for 0.9 to 7.8% of the biosynthetically labeled glycoproteins from organ culture supernatants. This component was 11.9% of the glycoproteins released by a monolayer culture of the established breast carcinoma cell line, MCF-7. alpha 1-Acid glycoprotein made up 0.7 to 3.1% of the labeled glycoproteins. alpha 1-Antichymotrypsin is a known neutral serine proteinase inhibitor with a particularly strong affinity for cathepsin G. alpha 1-Acid glycoprotein may function primarily as a potent immunomodulator by suppressing lymphoblastogenesis. These glycoproteins may thus have regulatory roles in the proteolytic modification of breast tissue and represent the tissue's own protecting shield against invading leukocytes.

Tissue-specific expression of a human polymorphic epithelial mucin (MUC1) in transgenic mice.

The human MUC1 gene codes for the core protein of a mucin which is expressed by glandular epithelia and the carcinomas which develop from these tissues. The core protein is aberrantly glycosylated in cancers, and some antibodies show specificity in their reactions with the cancer-associated mucin, which also contains epitopes recognized by T-cells from breast and pancreatic cancer patients. For evaluating the potential use of mucin-reactive antibodies and mucin-based immunogens in cancer patients, a mouse model, expressing the MUC1 gene product PEM (polymorphic epithelial mucin) as a self antigen, would be extremely useful. To this end, we have developed transgenic mouse strains expressing the human MUC1 gene product in a tissue-specific manner. The TG4 mouse strain was established using a 40-kilobase fragment containing 4.5 kilobases of 5' and 27 kilobases of 3' flanking sequence. The TG18 strain was developed using a 10.6-kilobase SacII fragment from the 40-kilobase fragment; this fragment contained 1.6 kilobases of 5' sequence and 1.9 kilobases of 3' flanking sequence. Both strains showed tissue specificity of expression of the MUC1 gene, which was very similar to the profile of expression seen in human tissues. The antibody SM-3 is directed to a core protein epitope, which is selectively exposed in breast cancers and which shows a more restricted distribution on normal human tissues. It was established that the distribution of the SM-3 epitope of PEM in the tissues of the transgenic mice is similar to that seen in humans. The transgenic mouse strains described here should form the basis for the development of a preclinical model for the evaluation of PEM-based antigens and of antibodies directed to PEM in cancer therapy.

Loss of heterozygosity analysis in primary mammary tumors and lung metastases of MMTV-MTAg and MMTV-neu transgenic mice.

Loss of heterozygosity (LOH) analysis has been used in many types of human cancer to localize putative tumor suppressor genes important in carcinogenesis. However, this approach has only recently been applied to transgenic mouse tumor models, which offer greater opportunity for detailed molecular genetic analysis of tumor initiation and progression. To explore the possible role of secondary genetic events in transgenic mouse mammary tumor development, we performed microsatellite-based allelotypes on primary mammary adenocarcinomas and lung metastases arising in mice transgenic for the polyomavirus middle T antigen under the control of the mouse mammary tumor virus promoter/enhancer (MMTV-MTAg mice) and on primary mammary adenocarcinomas arising in mice transgenic for the neu proto-oncogene (MMTV-neu mice). We examined a total of 80 microsatellite loci distributed throughout the mouse genome for LOH and observed high rates of specific chromosomal loss but very low rates of background allelic loss in these tumors. For the MMTV-MTAg mice, no individual chromosomes showed rates of LOH significantly above the background rates. For MMTV-neu mice, markers on chromosome 4 showed LOH in 82% of mammary tumors, whereas markers on chromosome 3 showed loss in 29% of tumors. These data suggest that the middle T antigen transgenic mice do not undergo whole chromosome loss or large genomic deletions as common mechanisms of tumor formation and that chromosomes 3 and 4 may contain tumor suppressor gene loci that play important roles in the development of neu-mediated mouse mammary tumors.

Development and characterization of breast cancer reactive monoclonal antibodies directed to the core protein of the human milk mucin.

A mucin molecule, which has a molecular weight of greater than 400,000 and which carries tumor associated epitopes recognized by monoclonal antibodies HMFG-1 and HMFG-2, has been purified from human skimmed milk by affinity chromatography followed by passage through a size exclusion column. While treatment of the mucin with hydrogen fluoride for 1 h at 4 degrees C removed the peripheral oligosaccharides, treatment with HF for 3 h at room temperature removed all of its lectin binding ability and revealed a dominant polypeptide of about 68,000. This appears to be the size of the mucin core protein. Monoclonal antibodies have been developed that react with the stripped and partially stripped molecule but not with the intact mucin. From the initial screening on histological sections one of these antibodies, SM-3, reacts with 91% of breast carcinomas but shows little or no reactivity on benign mammary tumors, normal resting, pregnant, or lactating breast. It appears that this monoclonal antibody is reacting with an epitope that is usually masked by oligosaccharide moieties in normal cells but which is exposed, perhaps due to aberrant glycosylation, in malignant cells.

Tolerance and immunity to MUC1 in a human MUC1 transgenic murine model.

The human epithelial mucin, MUC1, is a large transmembrane glycoprotein that is expressed on most simple epithelia. It is overexpressed and aberrantly glycosylated on many human epithelial tumors, including more than 90% of human breast cancers. MUC1 is of interest as an immunotherapy target because patients with breast, ovarian, and pancreatic cancers have T lymphocytes in their tumor-draining lymph nodes that can be induced to recognize and lyse MUC1-expressing tumor cells. We have produced a transgenic mouse model that expresses the human MUC1 molecule on an inbred C57Bl/6 background to investigate the effect of endogenous expression of MUC1 on the ability of mice to generate antitumor immunity to MUC1-expressing tumors. Transgenic mice expressed the human transgene in a pattern and level consistent with that observed in humans. Transgenic mice were tolerant to stimulation by MUC1 as evidenced by the ability of MUC1-expressing tumor cells to grow in these mice, whereas MUC1-expressing cells were eliminated from wild-type mice. Moreover, transgenic mice immunized with MUC1 peptides failed to exhibit immunoglobulin class switching to the IgG subtypes. These data suggest that endogenous expression of MUC1 protein by MUC1 transgenic mice induces T-cell tolerance to stimulation by MUC1. The transgenic mice will provide a useful model to investigate the mechanisms that regulate immunological tolerance to tumor antigens and will facilitate the investigation of anti-MUC1 immunotherapy formulations.

Inhibition of epidermal growth factor receptor tyrosine kinase fails to suppress adenoma formation in ApcMin mice but induces duodenal injury.

A highly selective, p.o. bioavailable irreversible inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase, N-[4-(3-chloro4-fluorophenylamino)-quinazolin-6-yl]-ac rylamide (CFPQA), was evaluated for its ability to prevent intestinal adenoma formation in ApcMin mice. Ten-week continuous dietary exposure to CFPQA at doses sufficient to abolish intestinal EGFR tyrosine phosphorylation failed to affect intestinal tumor multiplicity or distribution but induced flat mucosal lesions in the duodenum characteristic of chronic injury. Intestinal trefoil factor, an intestinal peptide that mediates antiapoptotic effects through an EGFR-dependent mechanism, was notably absent in adenomas but was highly expressed in flat duodenal lesions. We conclude that chronic inhibition of EGFR tyrosine kinase by CFPQA does not prevent adenomas in ApcMin mice but may induce duodenal injury.

Adenoma-specific alterations of protein kinase C isozyme expression in Apc(MIN) mice.

Members of the protein kinase C (PKC) family appear to play important roles in colorectal carcinogenesis. To investigate the potential involvement of PKC isozymes in adenomatous transformation induced by inactivation of the adenomatous polyposis coli (APC) gene product, we examined protein levels and localizations of ten PKC isozymes by immunohistochemistry in normal and adenomatous ileal epithelium of ApcMIN mice. Compared with surrounding normal epithelium, adenomas showed dramatically reduced staining for PKCs a, beta1, and zeta, as well as dysplasia-specific punctate nuclear staining of PKC mu. We conclude that reduced protein expression of PKC alpha, beta1, and zeta, and nuclear localization of PKC mu are markers of, and are perhaps involved in, adenomatous transformation induced by APC inactivation in ApcMIN mice.

Expression of an active proteinase inhibitor, alpha 1-antichymotrypsin, by human breast epithelial cells.

The synthesis of an active proteinase inhibitor, gp 66, by human breast epithelial cells is reported. This glycoprotein is identical to serum alpha 1-antichymotrypsin, which inhibits proteinases that cleave at hydrophobic residues. Immunohistological studies show the in vivo expression on normal secretory and ductal epithelial cells and on primary and metastatic adenocarcinomas. Immunoaffinity-purified gp 66 from MCF-7 culture supernatants is an active inhibitor of chymotrypsin as determined in a fluorogenic enzyme assay and can form stable 88 kDa enzyme-inhibitor complexes. The synthesis of a functional inhibitor may represent the epithelial cell's attempt to stabilize its extracellular milieu.

The epithelial mucin, MUC1, of milk, mammary gland and other tissues.

MUC1 is a mucin-type glycoprotein that is integrally disposed in the apical plasma membrane of the lactating epithelial cell and protrudes from the cell surface into the alveolar lumen where milk is stored. Envelopment of milk fat globules by this membrane accomplishes their secretion and conveys MUC1 into milk. The human form of this mucin has been detected in many other organs, tissues and body fluids. It projects from the cell surface as long filaments. In the human and a number of other species, MUC1 is polymorphic due to variable numbers of a tandemly repeated segment 20 amino acids in length. The individual codominantly expresses two alleles for the mucin so that differences in its size among individuals and between the two forms of an individual are observed. The tandem repeats are rich in serines and threonines which serve as O-glycosylation sites. Carbohydrate content of MUC1, as isolated from milk of human, bovine and guinea pig, is approximately 50%. The oligosaccharides carry substantial sialic acid at their termini and this accounts for two putative functions of this mucin, i.e., to keep ducts and lumens open by creating a strong negative charge on the surface of epithelial cells which would repel opposite sides of a vessel, and to bind certain pathogenic microorganisms. MUC1 is protease resistant (trypsin, chymotrypsin and pepsin) and large fragments of it can be found in the feces of some but not all breast-fed infants. MUC1 has a highly varied structure because of its polymorphism, qualitative and quantitative variations in its glycosylation between tissues, individuals and species, and differences due to divergence in the nucleotide sequences among species. Sequencing of the MUC1 gene for various species is showing promise of revealing unique evolutionary relationships and has already indicated conserved aspects of the molecule that may be functionally important. Among these are positions of serine, threonine and proline in the tandem repeats and a high degree of homology in the transmembrane and cytoplasmic segments of the molecule.

Spontaneous adenocarcinoma mouse models for immunotherapy.

Recent discoveries regarding the identification of tumor-associated antigens and antigen presentation have made successful immunotherapy strategies possible with little, if any, toxicity. Here, we describe transgenic mammary, pancreas, prostate, stomach and lung adenocarcinoma animal models that can be used to study various immunotherapeutic strategies. The challenge in developing a tumor vaccine is effective antigen presentation that elicits anti-tumor immune responses without precipitating autoimmunity. Clinical trials must be preceded by appropriate animal studies to demonstrate that the concepts can be translated into efficacious therapy for cancer. Although many xenograph or transplantable tumor models have been used, the most effective studies are in spontaneous tumor models. These models are clinically relevant, as tumors arise in an appropriate tissue background and in a host conditioned by the physiological events of neoplastic progression and tumorigenesis and in the context of a viable immune system.

MUC1-specific cytotoxic T lymphocytes eradicate tumors when adoptively transferred in vivo.

We have reported previously that MUC1 transgenic mice with spontaneous tumors of the pancreas (designated MET) naturally develop MHC class I-restricted, MUC1-specific CTLs as tumors progress (P. Mukherjee et al., J. Immunol., 165: 3451-3460, 2000). From these MET mice, we have isolated, expanded, and cloned naturally occurring MUC1-specific CTLs in vitro. In this report, we show that the CTL line is predominantly CD8+ T cells and expresses T-cell receptor Vbeta chains 5.1/5.2, 11, 13, and 2 and Valpha chains 2, 8.3, 3.2, and 11.1/11.2. These CTLs recognize several epitopes on the MUC1 tandem repeat with highest affinity to APGSTAPPA. The CTL clone, on the other hand, is 100% CD8+ cells and expresses a single Vbeta chain of 5.1/5.2 and Valpha2. It recognizes only the H-2Db class I-restricted epitope of MUC1, APGSTAPPA. When adoptively transferred, the CTLs were effective in eradicating MUC1-expressing injected tumor cells including mammary gland cells (C57mg) and B16 melanomas. These results suggest that MUC1-specific CTLs are capable of possibly preventing, or at least substantially delaying, MUC1-expressing tumor formation. To our knowledge, this is the first evidence that demonstrates that the naturally occurring MUC1-specific CTLs isolated from one tumor model has antitumor effects on other MUC1-expressing tumors in vivo. Therefore, our data confirm that MUC1 is an important tumor rejection antigen and can serve as a target for immunotherapy.

Evaluation of 5-aminosalicylic acid (5-ASA) for cancer chemoprevention: lack of efficacy against nascent adenomatous polyps in the Apc(Min) mouse.

Recent experimental and epidemiological evidence suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in the prevention of colorectal cancer. However, the toxicity associated with the long-term use of most classical NSAIDs has limited their usefulness for the purpose of cancer chemoprevention. Inflammatory bowel disease (IBD) patients, in particular, are sensitive to the adverse side effects of NSAIDs, and these patients also have an increased risk for the development of intestinal cancer. 5-Aminosalicylic acid (5-ASA) is an anti-inflammatory drug commonly used in the treatment of IBD and may provide protection against the development of colorectal cancer in these patients. To directly evaluate the ability of 5-ASA to suppress intestinal tumors, we studied several formulations of 5-ASA (free acid, sulfasalazine, and Pentasa) at multiple oral dosage levels [500, 2400, 4800, and 9600 parts/million (ppm)] in the adenomatous polyposis coli (Apc) mouse model of multiple intestinal neoplasia (Min). Although the ApcMin mouse is not a model of colitis-associated neoplasia, it is, nonetheless, a useful model for assessing the ability of anti-inflammatory agents to prevent tumor formation in a genetically preinitiated population of cells. We used a study design in which drug was provided ad libitum through the diet beginning at the time of weaning (28 days of age) until 100 days of age. We included 200 ppm of piroxicam and 160 ppm of sulindac as positive controls, and the negative control was AIN-93G diet alone. Treatment with either piroxicam or sulindac produced statistically significant reductions in intestinal tumor multiplicity (95% and 83% reductions in tumor number, respectively; P < 0.001 versus controls). By contrast, none of the 5-ASA drug formulations or dosage levels produced consistent dose-progressive changes in polyp number, distribution, or size, despite high luminal and serum concentrations of 5-ASA and its primary metabolite N-acetyl-5-ASA. Thus, 5-ASA does not seem to possess direct chemosuppressive activity against the development of nascent intestinal adenomas in the ApcMin mouse. However, because intestinal tumor development in the ApcMin mouse is driven by a germline mutation in the Apc gene rather than by chronic inflammation, we caution that these findings do not definitively exclude the possibility that 5-ASA may exert a chemopreventive effect in human IBD patients.

MUC1 epithelial mucin (CD227) is expressed by activated dendritic cells.

The MUC1 mucin (CD227) is a cell surface mucin originally thought to be restricted to epithelial tissues. We report that CD227 is expressed on human blood dendritic cells (DC) and monocyte-derived DC following in vitro activation. Freshly isolated murine splenic DC had very low levels of CD227; however, all DC expressed CD227 following in vitro culture. In the mouse spleen, CD227 was seen on clusters within the red pulp and surrounding the marginal zone in the white pulp. Additionally, we confirm CD227 expression by activated human T cells and show for the first time that the CD227 cytoplasmic domain is tyrosine-phosphorylated in activated T cells and DC and is associated with other phosphoproteins, indicating a role in signaling. The function of CD227 on DC and T cells requires further elucidation.

Evaluation of primary and secondary gastrointestinal bleeders.

To determine whether the diagnostic evaluation of patients admitted for nongastrointestinal disease, who subsequently bleed while in hospital (secondary bleeders), should differ from that of patients hospitalized with a primary diagnosis of GI bleeding, patients consecutively referred to a consultant service were prospectively evaluated. Ninety-four primary and 43 secondary bleeders underwent a detailed historical survey and endoscopic or radiologic diagnostic evaluation of the upper and lower gastrointestinal tract. Primary bleeders hemorrhaged with greater severity and potential or definitive bleeding sites were found in them more often than in secondary bleeders. Primary bleeders usually had upper gastrointestinal lesions, whereas secondary bleeders frequently had colonic bleeding. Prior historical events other than the use of nonsteroidal anti-inflammatory agents did not affect the source or severity of bleeding. The clinical spectra of primary and secondary bleeders differ so that evaluation of secondary bleeders of modest severity should be modified and often can be deferred until the underlying disease has been controlled.