Pathogenesis of Colitis in Germ-Free Mice Infected With EHEC O157:H7

Enterohemorrhagic Escherichia coli (EHEC) are strains of E. coli that express Shiga toxins (Stx) and cause hemorrhagic colitis. In some cases, disease can progress to hemolytic uremic syndrome, a potentially fatal form of kidney disease. Both enteric and renal disease are associated with the expression of stx genes, which are often carried on lysogenic phage. Toxin is expressed following induction and conversion of the phage to lytic growth. The authors previously used a germ-free mouse model to demonstrate that toxin gene expression is enhanced during growth in vivo and that renal disease is dependent on both prophage induction and expression of Stx2. In the current study, the authors document and quantify necrotizing colitis, examine the progression of enteric and renal disease, and determine the role of Stx2, phage genes, and the type 3 secretion system (T3SS) in bacterial colonization and colitis and systemic disease. By 1 day after inoculation, EHEC-monocolonized mice developed colitis, which decreased in severity thereafter. Systemic disease developed subsequently. Infection with EHEC mutant strains revealed that renal failure and splenic necrosis were absolutely dependent on the expression of Stx2 but that T3SS function and prophage excision were not necessary for systemic disease. In contrast, colitis was only partly dependent on Stx2. This study demonstrates that in germ-free mice, like in human patients, EHEC causes early colitis followed by renal failure and that systemic disease but not colitis is Stx2 dependent.

Anterior placental location influences onset and progress of labor and postpartum outcome

INTRODUCTION

The aim of the study is to evaluate whether placental location at term is associated with delivery outcome.

METHODS

A prospective study including 2354 patients with singleton pregnancy at term admitted for vaginal delivery was conducted. Placental position was determined before delivery by ultrasonographic examination performed transabdominally with women in the supine position. Maternal characteristics and delivery outcome such as premature rupture of membranes, induction of labor, mode and gestational age at delivery, indication for cesarean section, duration of the third stage, postpartum hemorrhage (PPH) and manual removal of placenta were correlated with anterior, posterior or fundal placental locations.

RESULTS

Among women enrolled: i) 1164 had an anterior placenta, ii) 1087 a posterior placenta, iii) 103 a fundal placenta. Women with anterior placenta showed: i) a higher incidence of induction of labor (p = 0.0001), especially for postdate pregnancies and prolonged prelabor rupture of membranes (p < 0.0001), ii) a higher rate of cesarean section rate for failure to progress in labor (p = 0.02), iii) a prolonged third stage (p = 0.01), iv) a higher incidence of manual removal of placenta (p = 0.003) and a higher rate of PPH in vaginal deliveries (p = 0.02).

DISCUSSION

The present study showed the influence of anterior placental location on the course of labor, with a later onset of labor, a higher rate of induction and cesarean section and postpartum complications. The reason for this influence on labor and delivery complications remains to be elucidated.

Sub-clinical organ damage in hypertension and obesity

BACKGROUND

The development of sub-clinical organ damage precedes and predicts the occurrence of cardiovascular (CV) events in hypertensive as well as in obese patients.

AIM AND METHODS

We investigated the prevalence and clinical correlates of organ damage (OD), namely carotid atherosclerosis (US scan) and urine albumin to creatinine ratio (three non-consecutive first morning samples) in a group of 164 obese patients and in an age- and gender-matched group of non-obese hypertensive patients.

RESULTS

There was a significantly greater prevalence and severity of OD in obese patients as compared to non-obese hypertensive patients. In particular obese patients more frequently had microalbuminuria (16 vs 7%, χ(2) 5.8, P=0.0157) and carotid abnormalities (53 vs 10%, χ(2) 69.5, P<0.0001) as well as higher urinary albumin excretion rate (-0.05 ± 0.52 vs -0.28 ± 0.43log ACR, P<0.0001) and carotid intima-media thickness (0.955 ± 0.224 vs 0.681 ± 0.171, <0.0001). Notably, the coexistence of hypertension and obesity did not entail a greater prevalence and severity of OD. Moreover, after adjusting for potentially confounding factors including blood pressure levels, diagnosis of diabetes, and lipid profile, morbidly obese patients showed a 5-fold, and 22-fold higher risk of having microalbuminuria, and carotid atherosclerosis, respectively.

CONCLUSIONS

Sub-clinical OD is highly prevalent in obese patients, even in the absence of high blood pressure. Hypertension and obesity seem to exert an independent, possibly non-additive role on the occurrence of organ damage.

Metabolic syndrome and ambulatory arterial stiffness index in non-diabetic patients with primary hypertension

Increased arterial stiffness and the presence of metabolic syndrome (MS) have been shown to predict cardiovascular events in patients with primary hypertension. We investigated the relationship between a recently proposed index of arterial stiffness derived from ambulatory blood pressure (BP) monitoring and MS in 156 untreated, non-diabetic patients with primary hypertension. Ambulatory arterial stiffness index (AASI) was defined as 1 minus the regression slope of diastolic over systolic BP readings obtained from 24-h recordings. A modified National Cholesterol Education Program definition for MS was used, with body mass index replacing waist circumference. The prevalence of MS was 23%. Patients with MS were more frequently male (0.0291) and had increased serum uric acid (P=0.0005), high-sensitivity C-reactive protein (P=0.0259), as well as total and low-density lipoprotein (LDL)-cholesterol (P=0.0374 and P=0.0350, respectively) as compared to those without MS. After adjusting for these confounders, the association between AASI and the presence of MS was statistically significant (P=0.0257). Moreover, the prevalence of increased AASI (upper tertile, that is >or=0.550) was greater in patients with MS (P=0.0156). After adjusting for age and 24-h mean BP, the presence of MS entailed a more than twofold greater risk for increased AASI (0.0280). MS is associated with increased AASI in non-diabetic patients with primary hypertension. These data support the role of this new index of arterial stiffness as a marker of risk and help to explain the high cardiovascular morbidity and mortality that is observed in hypertensive patients with MS.

Dansyl and dabsyl analytical constructs as tools for the accurate estimation of compounds in solid-phase synthesis

The presence of dansyl or dabsyl chromogenic moieties in a solid-phase analytical construct, an assembly of linkers/spacers/sensitizers for improving analytical characterization, allows the accurate estimation of products from solid-phase synthesis by UV detection during liquid chromatography-mass spectrometry analysis in the cleavage solution. The spectroscopic properties of dansylated molecules have been evaluated to verify the "compound-independent UV absorption" necessary for using the chromophore in the accurate estimation. First, measurements on commercial dansylated compounds were made, then a series of construct-like molecules were prepared by solution-phase synthetic procedures and their UV properties were determined. Compound calibration curves were determined, and UV absorption was shown to be both proportional to the compound concentration and compound-independent. An example of a dansyl construct derivative was then prepared on a polymeric matrix, and an accurate estimation using the calibration curves was carried out in the cleavage solution. Good agreement was found between the calculated amount of released compound using the UV calibration curves and the calculated amount using both (1)H NMR and LC/chemiluminescent nitrogen detection quantitative techniques. Preliminary studies using the dabsyl moiety as an improved chromophore with higher wavelength and extinction coefficient are also reported.

Substituted analogues of GV150526 as potent glycine binding site antagonists in animal models of cerebral ischemia

A series of analogues of the indole-2-carboxylate GV150526, currently in clinical trials as a potential neuroprotective agent for the control of the cerebral damage after stroke onset, was designed based on previous studies dealing with the electronic features of the north-east region of the glycine binding site associated with the NMDA receptor. In particular, the substitution of the para position of the terminal phenyl ring of GV150526 with suitable hydrophilic groups resulted in the identification of a new class of glycine antagonists. These compounds exhibited nanomolar in vitro affinity to the glycine binding site, high receptor selectivity, and outstanding in vivo potency. In particular, 3-[(E)-2-[(4-ureidomethylphenyl)aminocarbonyl]ethenyl]-4, 6-dichloroindole-2-carboxylic acid was found to be highly effective in the middle cerebral artery occlusion (MCAo) model in the rat, an animal model of focal ischemia, when given both prior to and after the occlusion of the middle cerebral artery. Notably, a significant neuroprotective effect was seen in this model postischaemia, when the administration of this compound was delayed up to 6 h from the occlusion of the middle cerebral artery, further confirming the wide therapeutic window seen for GV150526A.

Substituted indole-2-carboxylates as potent antagonists of the glycine binding site associated with the NMDA receptor

A novel series of indole-2-carboxylate analogues of GV150526 (1) in which the propenoic double bond was substituted with different "probes" or replaced by a isosteric cyclopropyl moiety were synthesized and evaluated for their affinity profile in order to obtain further information on the pharmacophoric model of the glycine binding site associated to the NMDA receptor.

New synthesis of substituted 2-carboxyindole derivatives: versatile introduction of a carbamoylethynyl moiety at the C-3 position

A novel series of 3-carbamoylethynyl-2-carboxyindoles, antagonists acting at the strychnine-insensitive glycine binding site associated with the NMDA receptor, has been synthesised. This new versatile approach involves the introduction of a 2-chloroethenyl moiety in position C-3 with subsequent derivatisation of the terminal carboxyl group, followed by an unusual elimination of HCl to afford the ethynyl functionality. This novel series of glycine antagonists was evaluated in terms of in vitro affinity at the glycine binding site and the most potent compound was tested in vivo in the NMDA-induced convulsions model in mice.

Substituted indole-2-carboxylates as in vivo potent antagonists acting as the strychnine-insensitive glycine binding site

A series of indole-2-carboxylates bearing suitable chains at the C-3 position of the indole nucleus was synthesized and evaluated in terms of in vitro affinity using [3H]glycine binding assay and in vivo potency by inhibition of convulsions induced by N-methyl-D-aspartate (NMDA) in mice. 3-[2-[(Phenylamino)carbonyl]ethenyl]-4,6-dichloroindole-2-carboxyl ic acid (8) was an antagonist at the strychnine-insensitive glycine binding site (noncompetitive inhibition of the binding of [3H]TCP, pA2 = 8.1) displaying nanomolar affinity for the glycine binding site (pKi = 8.5), coupled with high glutamate receptor selectivity (> 1000-fold relative to the affinity at the NMDA, AMPA, and kainate binding sites). This indole derivative inhibited convulsions induced by NMDA in mice, when administered by both iv and po routes (ED50 = 0.06 and 6 mg/kg, respectively). The effect of the substituents on the terminal phenyl ring of the C-3 side chain was investigated. QSAR analysis suggested that the pKi value decreases with lipophilicity and steric bulk of substituents and increases with the electron donor resonance effect of the groups present in the para position of the terminal phenyl ring. According to these results the terminal phenyl ring of the C-3 side chain should lie in a nonhydrophobic pocket of limited size, refining the proposed pharmacophore model of the glycine binding site associated with the NMDA receptor.