Lower polyunsaturated fatty acid levels and FADS2 expression in adult compared to neonatal keratinocytes are associated with FADS2 promotor hypermethylation.

Keratinocytes produce lipids that are critical for the skin barrier, however, little is known about the impact of age on fatty acid (FA) biosynthesis in these cells. We have examined the relationship between keratinocyte FA composition, lipid biosynthetic gene expression, gene promoter methylation and age. Expression of elongase (ELOVL6 and 7) and desaturase (FADS1 and 2) genes was lower in adult versus neonatal keratinocytes, and was associated with lower concentrations of n-7, n-9 and n-10 polyunsaturated FA in adult cells. Consistent with these findings, transient FADS2 knockdown in neonatal keratinocytes mimicked the adult keratinocyte FA profile in neonatal cells. Interrogation of methylation levels across the FADS2 locus (53 genomic sites) revealed differential methylation of 15 sites in neonatal versus adult keratinocytes, of which three hypermethylated sites in adult keratinocytes overlapped with a SMARCA4 protein binding site in the FADS2 promoter.

Climbazole increases expression of cornified envelope proteins in primary keratinocytes.

OBJECTIVE: Dandruff is a troubling consumer problem characterized by flaking and pruritus of the scalp and is considered a multifactorial condition with sebum, individual susceptibility and the fungus Malassezia all thought to play a part. The condition is commonly treated with shampoo products containing antifungal ingredients such as zinc pyrithione and climbazole. It is hypothesized that these ingredients may be delivering additional scalp skin benefits besides their antifungal activity helping to relieve dandruff effectively. The objective of this study was to evaluate the anti-dandruff ingredient climbazole for potential skin benefits using genomics and in vitro assays. METHODS: Microarray analysis was performed to profile gene expression changes in climbazole-treated primary human keratinocyte cells. Results were independently validated using qPCR and analysis of protein expression using ELISA and immunocytochemistry. RESULTS: Microarray analysis of climbazole-treated keratinocytes showed statistically significant expression changes in genes associated with the gene ontology groups encompassing epidermal differentiation, keratinization, cholesterol biosynthesis and immune response. Upregulated genes included a number encoding cornified envelope proteins such as group 3 late-cornified envelope proteins, LCE3 and group 2 small-proline-rich proteins, SPRR2. Protein analysis studies of climbazole-treated primary keratinocytes using ELISA and immunocytochemistry were able to demonstrate that the increase in gene transcripts translated into increased protein expression of these cornified envelope markers. CONCLUSION: Climbazole treatment of primary keratinocytes results in an upregulation in expression of a number of genes including those encoding proteins involved in cornified envelope formation with further studies demonstrating this did translate into increased protein expression. A climbazole-driven increase in cornified envelope proteins may improve the scalp skin barrier, which is known to be weaker in dandruff. These studies suggest climbazole, besides its antifungal activity, is delivering positive skin benefits helping to relive dandruff symptoms effectively.

Wrinkle reduction in post-menopausal women consuming a novel oral supplement: a double-blind placebo-controlled randomized study.

OBJECTIVE: The maintenance of youthful skin appearance is strongly desired by a large proportion of the world's population. The aim of the present study was therefore to evaluate the effect on skin wrinkling, of a combination of ingredients reported to influence key factors involved in skin ageing, namely inflammation, collagen synthesis and oxidative/UV stress. A supplemented drink was developed containing soy isoflavones, lycopene, vitamin C and vitamin E and given to post-menopausal women with a capsule containing fish oil. METHOD: We have performed a double-blind randomized controlled human clinical study to assess whether this cocktail of dietary ingredients can significantly improve the appearance of facial wrinkles. RESULTS: We have shown that this unique combination of micronutrients can significantly reduce the depth of facial wrinkles and that this improvement is associated with increased deposition of new collagen fibres in the dermis. CONCLUSION: This study demonstrates that consumption of a mixture of soy isoflavones, lycopene, vitamin C, vitamin E and fish oil is able to induce a clinically measureable improvement in the depth of facial wrinkles following long-term use. We have also shown, for the first time with an oral product, that the improvement is associated with increased deposition of new collagen fibres in the dermis.

Expression of acid-sensing ion channels in intestinal epithelial cells and their role in the regulation of duodenal mucosal bicarbonate secretion.

AIMS: As little is currently known about acid-sensing ion channels (ASICs) in intestinal epithelial cells, the aims of the present study were to investigate the expression and function of ASICs in intestinal epithelial cells, particularly their physiological role in the acid-stimulated duodenal mucosal bicarbonate secretion (DMBS). METHODS: RT-PCR and digital Ca²(+) imaging were used to determine the expression and function of ASICs in HT29 cells and SCBN cells, intestinal epithelial crypt cell lines. The acid-stimulated DMBS was measured in C57 black mice in vivo to study the role of ASICs in this physiological process. RESULTS: ASIC1a mRNA expression was detected in the duodenal mucosa stripped from mice and epithelial cell lines, in which cytoplasmic free Ca²(+) ([Ca²(+) ](cyt)) in response to extracellular acidosis was also increased. In Ca²(+) -containing solutions, acidosis (pH 6.0-5.0) raised [Ca²(+) ](cyt) in both HT29 cells and SCBN cells in a similar pH-dependent manner. Acidosis-induced increase in [Ca²(+) ](cyt) was markedly inhibited by amiloride (an ASICs blocker), SK&F96365 (a blocker for non-selective cation channels), or in Ca²(+) -free solutions; but was abolished by amiloride in Ca²(+) -free solutions. However, acidosis-induced increase in [Ca²(+) ](cyt) was slightly affected by U73122 (a PLC inhibitor), or nifedipine (a voltage-gated Ca²(+) channel blocker). After acidosis raised [Ca²(+) ](cyt) , stimulation of purinergic receptors with ATP further increased [Ca²(+) ](cyt) , but acidosis-induced increase in [Ca²(+) ](cyt) was not altered by suramin. Moreover, acid-stimulated murine DMBS was significantly attenuated by amiloride. CONCLUSION: Therefore, ASICs are functionally expressed in intestinal epithelial cells, and may play a role in acid-stimulated DMBS through a Ca²(+) signalling pathway.

Decoding epithelial signals: critical role for the epidermal growth factor receptor in controlling intestinal transport function.

The intestinal epithelium engages in bidirectional transport of fluid and electrolytes to subserve the physiological processes of nutrient digestion and absorption, as well as the elimination of wastes, without excessive losses of bodily fluids that would lead to dehydration. The overall processes of intestinal ion transport, which in turn drive the secretion or absorption of water, are accordingly carefully regulated. We and others have identified the epidermal growth factor receptor (EGFr) as a critical regulator of mammalian intestinal ion transport. In this article, we focus on our studies that have uncovered the intricate signalling mechanisms downstream of EGFr that regulate both chloride secretion and sodium absorption by colonocytes. Emphasis will be placed on the EGFr-associated regulatory pathways that dictate the precise outcome to receptor activation in response to signals that may seem, on their face, to be quite similar if not identical. The concepts to be discussed underlie the ability of the intestinal epithelium to utilize a limited set of signalling effectors to produce a variety of outcomes suitable for varying physiological and pathophysiological demands. Our findings therefore are relevant not only to basic biological principles, but also may ultimately point to new therapeutic targets in intestinal diseases where ion transport is abnormal.

Bradykinin regulates human colonic ion transport in vitro.

BACKGROUND AND PURPOSE: Kinins are acknowledged as important regulators of intestinal function during inflammation; however, their effects on human intestinal ion transport have not been reported. Here, we used muscle-stripped human colonic tissue and cultured T(84)-cell monolayers to study bradykinin (BK) actions on human intestinal ion transport. EXPERIMENTAL APPROACH: Ion transport was measured as changes in short-circuit current (I(sc)) across colonic epithelia mounted in Ussing chambers. KEY RESULTS: In intact tissue, there was a distinct polarity to BK-elicited I(sc) responses. Whereas basolateral BK stimulated sustained responses (EC(50)=0.5+/-0.1 microM), those to apical BK were more rapid and transient (EC(50)=4.1+/-1.2 nM). In T(84) cells, responses to both apical and basolateral BK were similar to those seen upon apical addition to intact tissues. Cross-desensitization between apical and basolateral domains was not observed. BK-induced responses were largely due to Cl(-) secretion as shown by their sensitivity to bumetanide and removal of Cl(-) from the bathing solution. Studies using selective agonists and antagonists indicate responses to BK are mediated by B(2) receptors. Finally, responses to basolateral BK in intact tissues were inhibited by tetrodotoxin (1 microM), atropine (1 microM), capsaicin (100 microM) and piroxicam (10 microM). BK-stimulated prostaglandin (PG)E(2) release from colonic tissue. CONCLUSIONS: BK stimulates human colonic Cl(-) secretion by activation of apical and basolateral B(2) receptors. Responses to apical BK reflect a direct action on epithelial cells, whereas those to basolateral BK are amplified by stimulation of enteric nerves and PG synthesis.

Leptin acts as a mitogenic and antiapoptotic factor for colonic cancer cells.

BACKGROUND: Obesity is associated with increased levels of leptin. The mitogenic actions of leptin have been identified in various cell types. Because obesity may be a risk factor for colonic cancer, the proliferative and antiapoptotic effects of leptin on colonic cancer cells and the role of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3-K) signalling were investigated. METHODS: Three human colonic cancer cell lines (T(84), HT29/Cl.19A and Caco-2) were treated with leptin. Cell proliferation was measured using the XTT colorimetric assay and apoptosis by a cell death enzyme-linked immunosorbent assay. Inhibitors of MAPK and PI3-K were used to evaluate the role of these signalling pathways. Phosphorylation of the downstream components extracellular signal-regulated kinase (ERK) 1/2 and Akt was detected by western blotting. RESULTS: Leptin increased cell number in all cell lines in a dose-dependent manner and reduced the number of apoptotic cells in a cell line-dependent manner. Leptin also caused ERK1/2 and Akt phosphorylation. Pretreatment with inhibitors of MAPK and PI3-K inhibited these responses, attenuated the mitogenic action of leptin and abolished its antiapoptotic effects. CONCLUSION: Chronic increases in leptin concentration may enhance the growth of colonic cancers via MAPK and PI3-K pathways. These effects of leptin could provide a link between obesity and colonic cancer, and may represent a target for anticancer drug development.

A role for guanylate cyclase C in acid-stimulated duodenal mucosal bicarbonate secretion.

Luminal acidification provides the strongest physiological stimulus for duodenal HCO3- secretion. Various neurohumoral mechanisms are believed to play a role in acid-stimulated HCO3- secretion. Previous studies in the rat and human duodenum have shown that guanylin and Escherichia coli heat-stable toxin, both ligands of the transmembrane guanylyl cyclase receptor [guanylate cyclase C (GC-C)], are potent stimulators for duodenal HCO3- secretion. We postulated that the GC-C receptor plays an important role in acid-stimulated HCO3- secretion. In vivo perfusion studies performed in wild-type (WT) and GC-C knockout (KO) mice indicated that acid-stimulated duodenal HCO3- secretion was significantly decreased in the GC-C KO animals compared with the WT counterparts. Pretreatment with PD-98059, an MEK inhibitor, resulted in attenuation of duodenal HCO3- secretion in response to acid stimulation in the WT mice with no further effect in the KO mice. In vitro cGMP generation studies demonstrated a significant and comparable increase in cGMP levels on acid exposure in the duodenum of both WT and KO mice. In addition, a rapid, time-dependent phosphorylation of ERK was observed with acid exposure in the duodenum of WT mice, whereas a marked attenuation in ERK phosphorylation was observed in the KO animals despite equivalent levels of ERK in both groups of animals. On the basis of these studies, we conclude that transmembrane GC-C is a key mediator of acid-stimulated duodenal HCO3- secretion. Furthermore, ERK phosphorylation may be an important intracellular mediator of duodenal HCO3- secretion.

Live probiotics protect intestinal epithelial cells from the effects of infection with enteroinvasive Escherichia coli (EIEC).

BACKGROUND: The colonic epithelium maintains a life long reciprocally beneficial interaction with the colonic microbiota. Disruption is associated with mucosal injury. AIMS: We hypothesised that probiotics may limit epithelial damage induced by enteroinvasive pathogens, and promote restitution. METHODS: Human intestinal epithelial cell lines (HT29/cl.19A and Caco-2) were exposed to enteroinvasive Escherichia coli (EIEC 029:NM), and/or probiotics (Streptococcus thermophilus (ST), ATCC19258, and Lactobacillus acidophilus (LA), ATCC4356). Infected cells and controls were assessed for transepithelial resistance, chloride secretory responses, alterations in cytoskeletal and tight junctional proteins, and responses to epidermal growth factor (EGF) stimulation. RESULTS: Exposure of cell monolayers to live ST/LA, but not to heat inactivated ST/LA, significantly limited adhesion, invasion, and physiological dysfunction induced by EIEC. Antibiotic killed ST/LA reduced adhesion somewhat but were less effective in limiting the consequences of EIEC invasion of cell monolayers. Furthermore, live ST/LA alone increased transepithelial resistance, contrasting markedly with the fall in resistance evoked by EIEC infection, which could also be blocked by live ST/LA. The effect of ST/LA on resistance was accompanied by maintenance (actin, ZO-1) or enhancement (actinin, occludin) of cytoskeletal and tight junctional protein phosphorylation. ST/LA had no effect on chloride secretion by themselves but reversed the increase in basal secretion evoked by EIEC. EIEC also reduced the ability of EGF to activate its receptor, which was reversed by ST/LA. CONCLUSIONS: Live ST/LA interact with intestinal epithelial cells to protect them from the deleterious effect of EIEC via mechanisms that include, but are not limited to, interference with pathogen adhesion and invasion. Probiotics likely also enhance the barrier function of naïve epithelial cells not exposed to any pathogen.

Inhibition of epithelial chloride secretion by butyrate: role of reduced adenylyl cyclase expression and activity.

Butyrate and other short-chain fatty acids (SCFAs) are found at high concentrations in the colonic lumen and affect multiple epithelial cell functions. To better understand how SCFAs regulate ion transport, we investigated the effects of SCFAs on Cl(-) secretion in human colonic epithelial cell line T(84). Butyrate inhibited Cl(-) secretory responses to prostaglandin E(2), forskolin, and cholera toxin. Other SCFAs were less effective or inactive. Reduced secretion was associated with decreased synthesis of the second messenger cAMP rather than increased degradation. Expression and activity of adenylyl cyclase were decreased by butyrate, whereas phosphodiesterase activity was unaffected and phosphodiesterase inhibition did not reverse the effects of butyrate on Cl(-) secretion. Furthermore, butyrate decreased expression of the basolateral Na-K-2Cl cotransporter, indicating that it might modulate the secretory capacity of the cells. However, butyrate did not affect secretory responses to the calcium-dependent secretagogue carbachol, cAMP analogs, or uroguanylin, indicating that normal secretory responses to adequate levels of second messengers in butyrate-treated T(84) cells are possible. These results show that butyrate affects several aspects of epithelial Cl(-) secretion, including second messenger generation and expression of key ion transporters. However, these effects may not all be equally important in determining Cl(-) secretion in response to physiologically relevant secretagogues.

Phosphatidylinositol 3-kinase-dependent pathways oppose Fas-induced apoptosis and limit chloride secretion in human intestinal epithelial cells. Implications for inflammatory diarrheal states.

The epithelial lining of the intestine serves as a barrier to lumenal bacteria and can be compromised by pathologic Fas-mediated epithelial apoptosis. Phosphatidylinositol (PI)3-kinase signaling has been described to limit apoptosis in other systems. We hypothesized that PI3-kinase-dependent pathways regulate Fas-mediated apoptosis and barrier function in intestiynal epithelial cells (IEC). IEC lines (HT-29 and T84) were exposed to agonist anti-Fas antibody in the presence or absence of chemical inhibitors of PI3-kinase (LY294002 and wortmannin). Apoptosis, barrier function, changes in short circuit current (DeltaI(sc)), and expression of adhesion molecules were assessed. Inhibition of PI3-kinase strongly sensitized IEC to Fas-mediated apoptosis. Expression of constitutively active Akt, a principal downstream effector of the PI3-kinase pathway, protected against Fas-mediated apoptosis to an extent that was comparable with expression of a genetic caspase inhibitor, p35. PI3-kinase inhibition sensitized to apoptosis by increasing and accelerating Fas-mediated caspase activation. Inhibition of PI3-kinase combined with cross-linking Fas was associated with increased permeability to molecules that were <400 Da but not those that were >3,000 Da. Inhibition of PI3-kinase resulted in chloride secretion that was augmented by cross-linking Fas. Confocal analyses revealed polymerization of actin and maintenance of epithelial cell adhesion molecule-mediated interactions in monolayers exposed to anti-Fas antibody in the context of PI3-kinase inhibition. PI3-kinase-dependent pathways, especially Akt, protect IEC against Fas-mediated apoptosis. Inhibition of PI3-kinase in the context of Fas signaling results in increased chloride secretion and barrier dysfunction. These findings suggest that agonists of PI3-kinase such as growth factors may have a dual effect on intestinal inflammation by protecting epithelial cells against immune-mediated apoptosis and limiting chloride secretory diarrhea.

Insulin and IGF-I inhibit calcium-dependent chloride secretion by T84 human colonic epithelial cells.

D-Myo-inositol (3,4,5,6) tetrakisphosphate [Ins(3,4,5,6)P(4)] or phosphatidylinositol 3-kinase (PI 3-kinase) activity acts to inhibit calcium-dependent chloride secretion in T84 colonic epithelial cells. To further distinguish between the contributions of these two signaling pathways to the inhibition of secretion, we studied effects of insulin, because the insulin receptor links to PI 3-kinase but not to pathways postulated to generate Ins(3,4,5,6)P(4). Chloride secretion across T84 cell monolayers was studied in Ussing chambers. Activation of PI 3-kinase was assessed by Western blotting. Basolateral, but not apical, addition of insulin inhibited carbachol- and thapsigargin-induced chloride secretion in a time- and concentration-dependent fashion. Insulin-like growth factor-I (IGF-I) had similar effects. Insulin had no effect on Ins(3,4,5,6)P(4) levels, and the inhibitory effects of insulin and IGF-I on chloride secretion were fully reversed by the PI 3-kinase inhibitors wortmannin and LY-294002. Western blot analysis showed that both insulin and IGF-I recruited the 85-kDa regulatory and 110-kDa catalytic subunits of PI 3-kinase to anti-phosphotyrosine immunoprecipitates. In conclusion, insulin and IGF-I act to inhibit calcium-dependent chloride secretion through a PI 3-kinase-dependent pathway. Because insulin is released in a pulsatile fashion postprandially and IGF-I levels are elevated in pathological settings, our findings may have physiological and/or pathophysiological significance.

Cloning, expression, signaling mechanisms, and membrane targeting of P2Y(11) receptors in Madin Darby canine kidney cells.

The P2Y(11) receptor is hypothesized to link to both G(s) and G(q), although this proposition is based on expression and separate assays of G(s) and G(q) function in different cell types [J Biol Chem 1997;272:31969-31973]. We have cloned and characterized a canine P2Y(11)-like (cP2Y(11)) receptor from cultured Madin Darby canine kidney (MDCK-D1) cells. When cP2Y(11) receptors are expressed in canine thymocyte (CF2Th) cells that normally lack functional purinergic responses, ADP beta S stimulates phosphatidylinositol (PI) hydrolysis, Ca(2+) mobilization, and cAMP accumulation. Pharmacologic analysis indicates that the stimulation of cAMP production is direct and not a result of eicosanoid synthesis, activation of PKC, or elevation of cell Ca(2+). The rank order of potency for stimulation of PI hydrolysis by cP2Y(11) receptors (adenosine 5'-(2-O-thio) diphosphate = 2-methylthio-ADP >/= 2-methylthio-ATP >> ADP > ATP) differs from that of hP2Y(11) receptors. Microscopic examination of MDCK-D1 cells expressing carboxyl-terminal green fluorescent protein (GFP)-tagged cP2Y(11) (cP2Y(11)-GFP) receptors indicates primarily basolateral (BL) targeting. BL addition of 200 microM ADP beta S to confluent monolayers of MDCK-D1 cells produces an increase in short circuit current (I(sc)) (11.6 +/- 1.6 microA/cm(2)) whereas apical addition of agonist has no effect, confirming targeting of functional endogenous P2Y(11) receptors to the BL surface. In contrast, when either cP2Y(11) or cP2Y(11)-GFP is overexpressed in MDCK-D1 cells, the sensitivity of I(sc) to BL agonist increases by nearly 2 orders of magnitude, as if receptor density normally limited agonist potency; moreover, apical addition of ADP beta S now produces an increase in I(sc) but with low potency. The data support the BL localization of cP2Y(11) receptors and receptor coupling to changes in I(sc) in MDCK-D1 cells except in cases in which receptors are overexpressed; receptor overexpression leads to altered sensitivities and sites of coupling to physiologic responses.

Differential effects of apical and basolateral uridine triphosphate on intestinal epithelial chloride secretion.

Our goal was to examine the sidedness of effects of the purinergic agonist, uridine 5'-triphosphate (UTP), on Cl(-) secretion in intestinal epithelial cells. We hypothesized that UTP might exert both stimulatory and inhibitory effects. All studies were conducted with T84 intestinal epithelial cells. UTP induced Cl(-) secretion in a concentration-dependent fashion. Responses to serosally added UTP were smaller and more transient than those evoked by mucosal addition, but there was no evidence that mucosal responses involved cAMP-dependent mechanisms. Pretreatment with serosal UTP inhibited subsequent Ca(2+)-dependent Cl(-) secretion induced by carbachol or thapsigargin, or secretion induced by mucosal UTP, in a manner that was reversed by a tyrosine kinase inhibitor. The inhibitory effect of serosal UTP on Cl(-) secretion was not additive with that of carbachol, known to exert its inhibitory effects through the tyrosine kinase-dependent generation of inositol 3,4,5,6-tetrakisphosphate [Ins(3,4,5,6)P(4)]. Moreover, responses to both serosal and mucosal UTP were reduced by prior treatment of T84 cells with carbachol. Finally, serosal, but not mucosal, UTP evoked an increase in Ins(3,4,5,6)P(4). We conclude that different signaling mechanisms lie downstream of apical and basolateral UTP receptors in epithelial cells, at least in the intestine. These differences may be relevant to the use of UTP as a therapy in cystic fibrosis.

Possible mechanisms of diarrheal side effects associated with the use of a novel chemotherapeutic agent, flavopiridol.

The novel cyclin-dependent kinase inhibitor flavopiridol has recently completed Phase I trials for the treatment of refractory neoplasms. The dose-limiting toxicity observed with this agent was severe diarrhea. Because the compound otherwise showed promise, the present study sought to determine possible mechanisms underlying the diarrheal side effects. Flavopiridol was tested for its ability to modify chloride secretory responses of the human colonic epithelial cell line, T84. Studies were conducted in vitro in modified Ussing chambers. High concentrations of flavopiridol (10(-4) M), above those likely to be clinically relevant, had a direct stimulatory effect on chloride secretion, probably ascribable to an increase in cyclic AMP. Lower, clinically relevant concentrations of flavopiridol (10(-6) M) had no effect on chloride secretion by themselves but potentiated responses to the calcium-dependent secretagogue, carbachol. The drug also potentiated responses to thapsigargin and taurodeoxycholate and reversed the inhibitory effects of carbachol and epidermal growth factor on calcium-dependent chloride secretion. Pretreatment with the cyclic AMP-dependent secretagogue, forskolin, potentiated responses to flavopiridol, but not vice versa. Thus, diarrheal side effects induced by flavopiridol are likely multifactorial in origin and may involve interactions with endogenous secretagogues such as acetylcholine and bile acids. A better understanding of the diarrhea induced by flavopiridol should allow optimization of therapy with this otherwise promising drug and/or the development of related agents with improved toxicity profiles.

Clinical usefulness of white blood cell count after cesarean delivery.

OBJECTIVE: To examine changes in white blood cell (WBC) count after cesarean and estimate risk of postoperative infection. METHODS: We measured complete blood cell counts at admission and on postoperative day 1 for 458 women who had cesareans. Information from charts was abstracted, and definitions of infectious outcomes and fever were applied by three physicians masked to laboratory results. We examined changes in absolute and relative WBC counts by labor status. Likelihood ratios for postoperative infection were calculated for statistically distinct categories of percentage changes. RESULTS: We excluded 60 women with chorioamnionitis. Of the remainder, 34 (8.5%) developed endometritis and three (0.8%) pneumonia. Women who labored before cesarean (n = 198) had higher antepartum (P <.001) and postoperative day 1 (P <.001) WBC counts than those who did not (n = 200). However, change in WBC count after cesarean relative to antepartum was similar for both groups (P =.41), averaging a 22% increase. We grouped percentage changes into the following three levels: up to 24%, 25-99%, and at least 100%. The lowest level (n = 246) corresponded to a category-specific likelihood ratio for diagnosis of serious postpartum infection of 0. 5 (95% confidence interval [CI] 0.3, 0.8), the midlevel (n = 141) to a category-specific likelihood ratio of 1.7 (95% CI 1.2, 2.3), and the highest level (n = 11) to a category-specific likelihood ratio of 5.8 (95% CI 1.8, 18.7). CONCLUSION: Labor influenced postcesarean WBC counts but did not obscure changes associated with infection. Information gained from changes in WBC counts can be used to assess risk of infection.

Chloride secretion by the intestinal epithelium: molecular basis and regulatory aspects.

Chloride secretion is the major determinant of mucosal hydration throughout the gastrointestinal tract, and chloride transport is also pivotal in the regulation of fluid secretion by organs that drain into the intestine. Moreover, there are pathological consequences if chloride secretion is either reduced or increased such as in cystic fibrosis and secretory diarrhea, respectively. With the molecular cloning of many of the proteins and regulatory factors that make up the chloride secretory mechanism, there have been significant advances in our understanding of this process at the cellular level. Similarly, emerging data have clarified the intercellular relationships that govern the extent of chloride secretion. The goal of our article is to review this area of investigation, with an emphasis on recent developments and their implications for the physiology and pathophysiology of chloride transport.