The enteroendocrine cell system of the mammalian gastrointestinal tract is comprised of at least 16 different subpopulations. Each subpopulation shows a characteristic distribution along both the crypt-villus and cephalocaudal axes. In both the small intestine and colon of adult mice, multilabel immunohistochemistry has demonstrated that two or more neuroendocrine products can be coexpressed in various combinations in single cells along the crypt-villus axis, suggesting that enteroendocrine phenotypes may be actively regulated. Using bromodeoxyuridine (BrdU) incorporation and multilabel immunohistochcmistry, we have previously demonstrated an enteroendocrine cell differentiation pathway consisting of two subpopulations of cells in the mouse proximal small intestinmne involving the sequential expression of substance P, serotonin, and secretin in cells migrating out of the crypts into the villi, and a second involving the expression of substance P and serotonin in cells which remain in the crypts. In this report, we use double label immunohistochemistry and BrdU incorporation to define the temporal and spatial interrelationships between gastrin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-I), and gastric inhibitory peptide (GIP) immunoreactive cells in the mouse proximal small intestine. The expression of these products was compared with that of substance P, serotonin, and secretin. Minimal overlap of expression was found in cells immunoreactive for substance P or serotonin with gastrin, CCK, GLP-1, or GIP; however, secretin was found colocalized in villus-associated gastrin, CCK, and GLP-1 containing cells. We demonstrate that, similar to the bidirectionally migrating substance P and serotonin expressing cells, gastrin, CCK, GLP-1, and secretin are expressed in upwardly migrating cells, and gastrin, CCK, and GLP-1 are expressed in downwardly migrating cells that fail to express secretin. GIP containing cells only rarely coexpressed any of the products examined, but were found both in the villi and the crypts, suggesting both upwardly and downwardly migrating populations. These findings demonstrate several novel enteroendocrine cell differentiation pathways. In addition, the expression of secretin 0 1994 WILEY-LISS, INC.in the villi, but not in the crypts, by two otherwise distinct differentiation pathways, and the lack of secretin expression by villus-associated GIP expressing cells, suggests that local factors present in the crypts and/or on the villi are necessary, but not sufficient, for secretin expression.

Precise spatial interrelationships exist between substance P, serotonin, and secretin containing enteroendocrine cells in the gastrointestinal tract of mice. In the proximal small intestine these products are coexpressed in various combinations in single enteroendocrine cells along the crypt to villus axis in a pattern that suggests the sequential expression of substance P, serotonin, and secretin. In this report we use bromodeoxyuridine (BrdU) and multilabeling immunohistochemistry to define the temporal and spatial interrelationships between substance P, serotonin, and secretin immunoreactive cells in the mouse proximal small intestine. Our findings demonstrate the sequential expression of substance P, serotonin, and secretin in a population of upwardly migrating enteroendocrine cells and, furthermore, identify a population of crypt associated cells coexpressing substance P and serotonin that fails to traverse this pathway. The lack of secretin immunoreactive cells in the crypts suggests that local factors present in the crypts and/or on villi regulate secretin expression. The combined use of BrdU and multilabeling immunohistochemistry provides a method for defining enteroendocrine cell differentiation pathways throughout the gastrointestinal tract. 0 1992 Wiley-Liss, Inc.

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After a temporary suspension of hepatitis B vaccination (HBV) for low-risk newborns in July 1999, some hospitals still do not offer HBV to these infants. A semi-structured telephone survey of medical directors from a national random sample of 296 hospital nurseries was completed from August 2000 to April 2001 and analyzed using qualitative techniques. Directors of 201 of 290 eligible nurseries (71%) participated. Twenty-ight nurseries have never offered HBV to low-risk newborns ("Never Offered HBV") and 37 nurseries had offered HBV to low-risk newborns before July 1999, but discontinued this practice after the temporary suspension ("Discontinued HBV"). Common reasons for not offering HBV to low-risk newborns were difficulty with reimbursement and convenience of outpatient administration. In addition, directors of "Never Offered HBV" nurseries cited low disease incidence in their patient population, whereas directors of "Discontinued HBV" cited preference for the combination hepatitis B-Haemophilus influenza type b vaccine as important factors. Multi-faceted interventions may be necessary to increase HBV use in the nursery.

ABSTRACT. Objective. Hepatitis B vaccination (HBV) is unlike any other immunization series because it can be initiated in the hospital nursery. The objective of this study was to describe how hospital nurseries develop HBV policies and to describe the sources of information used for learning about national HBV recommendations.Methods. A cross-sectional telephone survey was conducted on a national random sample of nursery medical directors of 290 hospital nurseries representing all 50 states. The outcomes measured were methods used by hospital nurseries to develop HBV policy and sources of information used by nursery directors to learn about national HBV recommendations.Results. Directors at 207 (71%) of 290 eligible nurseries responded. Of the 184 nurseries that have considered developing an HBV policy, the most common method was through a formal committee (43%). In 104 (57%) of these nurseries a nurse was involved in policy development, and in 15 (8%) the nurse manager initiated the process. The most common source of initial information about the July 1999 announcement to suspend the nursery dose of HBV was the American Academy of Pediatrics. The most common initial source of information about the availability of thimerosal-free HBV was pharmaceutical companies. Physician, nurse, and pharmacist colleagues were cited as sources of information with similar frequency (12, 11, and 20 cases, respectively).Conclusions. Physicians are not the sole initiators and developers of HBV policy in the newborn nursery. Although almost all nurseries designate a physician as a nursery director, in many cases (55% of cases) the position is "rotating" or as part of another administrative position (63% of cases). Many hospital nurseries involve nurses and pharmacists in key roles to stay current with HBV recommendations and to develop subsequent policy. Using nonphysician national organizations as additional channels of information might expedite dissemination about changes in HBV recommendations and, as a result, improve nursery awareness and adoption of national HBV guidelines. T he hepatitis B vaccination (HBV) series is unlike other pediatric vaccinations because it can be routinely initiated in an inpatient settingthe hospital nursery. The newborn nursery represents the first opportunity to immunize children and establish immunization practices and attitudes at the family and individual levels. The newborn period may be a time when parents are especially receptive to information about immunizations, because HBV at birth is associated with timely receipt of other vaccines. 1 In addition, a nursery's immunization policy can greatly influence the adoption of vaccination recommendations by individual health care providers in the same community. 2 In July 1999, the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) instituted changes in HBV recommendations for low-risk infants-those born to mothers who test negative for hepatitis B surface antigen. 3 Because of the potential risk of thimer...

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