Sarah Mount Patrick

Bifidobacterium bifidum reduces apoptosis in the intestinal epithelium in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating intestinal disease of neonates, and clinical studies suggest the beneficial effect of probiotics in NEC prevention. Recently, we have shown that administration of Bifidobacterium bifidum protects against NEC in a rat model. Intestinal apoptosis can be suppressed by activation of cyclooxygenase-2 (COX-2) and increased production of prostaglandin E(2) (PGE(2)). The present study investigates the effect of B. bifidum on intestinal apoptosis in the rat NEC model and in an intestinal epithelial cell line (IEC-6), as a mechanism of protection against mucosal injury. Premature rats were divided into the following three groups: dam fed, hand fed with formula (NEC), or hand fed with formula supplemented with B. bifidum (NEC + B. bifidum). Intestinal Toll-like receptor-2 (TLR-2), COX-2, PGE(2), and apoptotic regulators were measured. The effect of B. bifidum was verified in IEC-6 cells using a model of cytokine-induced apoptosis. Administration of B. bifidum increased expression of TLR-2, COX-2, and PGE(2) and significantly reduced apoptosis in the intestinal epithelium of both in vivo and in vitro models. The Bax-to-Bcl-w ratio was shifted toward cell survival, and the number of cleaved caspase-3 positive cells was markedly decreased in B. bifidum-treated rats. Experiments in IEC-6 cells showed anti-apoptotic effect of B. bifidum. Inhibition of COX-2 signaling blocked the protective effect of B. bifidum treatment in both in vivo and in vitro models. In conclusion, oral administration of B. bifidum activates TLR-2 in the intestinal epithelium. B. bifidum increases expression of COX-2, which leads to higher production of PGE(2) in the ileum and protects against intestinal apoptosis associated with NEC. This study indicates the ability of B. bifidum to downregulate apoptosis in the rat NEC model and in IEC-6 cells by a COX-2-dependent matter and suggests a molecular mechanism by which this probiotic reduces mucosal injury and preserves intestinal integrity.

Clinical Recognition and Management of Tularemia in Missouri: A Retrospective Records Review of 121 Cases

BACKGROUND Clinical recognition of tularemia is essential for prompt initiation of appropriate antibiotic treatment. Although fluoroquinolones have desirable attributes as a treatment option, limited data on efficacy in the US setting exist. METHODS To define the epidemiology of tularemia in Missouri, and to evaluate practices and outcomes of tularemia management in general, we conducted a detailed retrospective review and analysis of clinical records for patients reported to the state from 2000 to 2007. RESULTS We reviewed records of 121 of 190 patients (64%) reported with tularemia; 79 (65%) were males; the median age was 37 years. Most patients presented with ulceroglandular (37%) and glandular (25%) forms of tularemia, followed by pneumonic (12%), typhoidal (10%), oculoglandular (3%), and oropharyngeal (2%) forms. Most cases (69%) were attributed to tick bites. Median incubation period was 3 days (range, 1-9 days), and patients sought care after a median of 3 days of illness (range, 0-44 days). Systemic disease occurred more commonly in older patients. Patients were prescribed tetracyclines (49%), aminoglycosides (47%), and fluoroquinolones (41%). Nine of 10 patients treated with ciprofloxacin for ≥10 days recovered uneventfully, without accompanying aminoglycosides or tetracyclines. CONCLUSIONS Tularemia is frequently initially misdiagnosed. A thorough exposure history, particularly for tick bites, and awareness of clinical features may prompt clinicians to consider tularemia and facilitate appropriate testing. Promising success with oral fluoroquinolones could provide an acceptable alternative to intravenous aminoglycosides or long courses of tetracyclines where clinically appropriate.

Active Transport of Bile Acids Decreases Mucin 2 in Neonatal Ileum: Implications for Development of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of premature infants, but its etiology remains unclear. We have previously shown that mucin 2 (Muc2) positive goblet cells are significantly decreased in NEC. We have also shown that ileal bile acids (BAs) are significantly increased during the development of this disease. Because BAs can affect mucins, we hypothesized that elevated ileal BAs contribute to decreased Muc2 in experimental NEC. The role of Muc2 in NEC was evaluated in Winnie +/+ mice, a strain that produces aberrant Muc2. Muc2 and trefoil factor 3 (Tff3) were assessed in neonatal rats subjected to the NEC protocol when bile acids were removed, and in ileal explants from newborn and older rats cultured with and without BAs. Further, the role of active transport of BAs was determined using neonatal rats given the apical sodium dependent bile acid transporter (Asbt) inhibitor SC-435 and in neonatal Asbt knockout mice subjected to the NEC protocol. Mice with aberrant Muc2 had significantly greater incidence and severity of NEC. Using both in vivo and ex vivo techniques, we determined that BAs decrease Muc2 positive cells in neonatal but not older ileum. However, Tff3 positive cells are not decreased by BAs. In addition, active transport of BAs is required for BAs to decrease Muc2 in immature ileum. These data show that functional Muc2 plays a critical role in the prevention of NEC and BAs can potentiate the decreased Muc2 in disease development. Further, BAs have a more profound effect on Muc2 in immature versus older ileum, which may explain at least in part why NEC occurs almost exclusively in premature infants.

Apical sodium-dependent bile acid transporter upregulation is associated with necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of premature infants. Previously, we showed that luminal bile acids (BAs) are increased and correlated with disease development and that the apical sodium-dependent BA transporter (ASBT), which transports BAs from the ileal lumen into enterocytes, is upregulated in rats with NEC. We hypothesized that intraenterocyte, rather than luminal, BAs are associated with NEC and that upregulation of ASBT may be a mechanism by which this occurs. Neonatal rats with or without the ASBT inhibitor SC-435, mice in which ASBT was knocked out, and mice that overproduce BAs were subjected to the NEC protocol. Disease development, ASBT, and the farnesoid X receptor protein, along with luminal and intraenterocyte BA levels, were assessed. In addition, ileal sections from premature infants with and without NEC were examined for ASBT via immunohistology and real-time PCR. When BAs were not transported into enterocytes (rats given SC-435 and ASBT knockout mice), severity and incidence of NEC were reduced. In contrast, in mice that overproduce BAs, ASBT was elevated, intraenterocyte BAs were increased, and disease development was increased. ASBT staining was more intense on the apical membrane of ileal enterocytes from premature infants with NEC than premature infants with non-NEC diagnoses. In addition, ASBT mRNA levels were significantly higher in infants with NEC. These data show that accumulation of intraenterocyte BAs contributes to disease development, elevated ASBT increases disease severity in experimental models of NEC, and ASBT is elevated in human NEC. These data confirm that BAs and upregulation of ASBT play a crucial role in NEC pathogenesis and suggest that inhibition of ASBT could be utilized as a therapeutic modality against this disease.

Using PCR-Based Detection and Genotyping to Trace Streptococcus salivarius Meningitis Outbreak Strain to Oral Flora of Radiology Physician Assistant

We recently investigated three cases of bacterial meningitis that were reported from a midwestern radiology clinic where facemasks were not worn during spinal injection of contrast agent during myelography procedures. Using pulsed field gel electrophoresis we linked a case strain of S. salivarius to an oral specimen of a radiology physician assistant (RPA). We also used a real-time PCR assay to detect S. salivarius DNA within a culture-negative cerebrospinal fluid (CSF) specimen. Here we extend this investigation through using a nested PCR/sequencing strategy to link the culture-negative CSF specimen to the case strain. We also provide validation of the real-time PCR assay used, demonstrating that it is not solely specific for Streptococcus salivarius, but is also highly sensitive for detection of the closely related oral species Streptococcus vestibularis. Through using multilocus sequence typing and 16S rDNA sequencing we further strengthen the link between the CSF case isolate and the RPA carriage isolate. We also demonstrate that the newly characterized strains from this study are distinct from previously characterized S. salivarius strains associated with carriage and meningitis.

Physiological and coordinate downregulation of the NPC1 and NPC2 genes are associated with the sequestration of LDL-derived cholesterol within endocytic compartments

The Niemann‐Pick C1 and C2 (NPC1 and NPC2) proteins have a central role in regulating the transport of lipoprotein‐derived cholesterol from endocytic compartments to the endoplasmic reticulum for esterification by acyl‐CoA:cholesterol acyltransferase (ACAT) and feedback inhibition of the sterol regulatory element‐binding protein (SREBP) pathway. Since the NPC1 gene/protein has recently been shown to be downregulated by feedback inhibition of the SREBP pathway, the present study was performed to determine whether physiological downregulation of the NPC1 gene/protein alters the transport and metabolism of low‐density lipoprotein (LDL)‐derived cholesterol in human fibroblasts. To perform this study, three different culture conditions were used that included fibroblasts grown in lipoprotein‐deficient serum (LPDS), LPDS supplemented with LDL, and LPDS supplemented with LDL, followed by equilibration in the absence of LDL to allow the transport of LDL‐derived cholesterol from endocytic compartments and equilibration of cellular sterol pools. The results from this study indicated that in addition to the NPC1 gene/protein, the NPC2 gene/protein was also downregulated by LDL‐derived cholesterol‐dependent feedback inhibition and that downregulation of both the NPC1 and NPC2 genes/proteins was associated with the sequestration of LDL‐derived cholesterol within endocytic compartments, including late endosomes/lysosomes after equilibration. Therefore, it is proposed that physiological and coordinate downregulation of the NPC1 and NPC2 genes/proteins promotes the sequestration of LDL‐derived cholesterol within endocytic compartments and serves a role in maintaining intracellular cholesterol homeostasis. J. Cell. Biochem. 108: 1102–1116, 2009.

411 Developmental Regulation of Sam Pointed Domain Ets Factor (SPDEF) in Rat Ileum Cultured With Bile Acids

fibers as a percentage of total tissue area (μm2). The nerve volume densities were significantly decreased in the jejunum (23.7 vs. 31.3; p 0.05) and duodenum (30.1 vs. 28.8; p > 0.05). These findings suggest that endogenous microbiota are necessary for the normal patterning of the ENS in the early postnatal period, particularly in the mid to distal small intestine and colon. Further studies are needed to determine whether the mechanisms by which the endogenous microbiota act on the ENS involve a direct effect on neural cells.