An update on histamine H3 receptors and gastrointestinal functions

The distribution and functions of histamine H₃ receptors in the gastrointestinal tract is reviewed with particular reference to the effects on gastric acid secretion, mucosal protection, and intestinal motility. Histamine H₃ receptor activation has negative effects on acid secretion induced by indirect secretagogues in cats, dogs, and rabbits; less clear effects were found in rats. An inhibitory effect on histamine release induced by different stimuli was observed in rats, rabbits, and dogs after H₃ receptor agonists, thus supporting the idea that H₃ receptors occur in ECL cells. (R)--methylhistamine has a marked protective effect against gastric lesions induced by ethanol in rats, being slightly less effective against aspirin and stress. H₃ receptor activation decreases the intestinal motility induced by electrical stimulation in a variety of gut preparations, reducing both cholinergic and NANC neurotransmitter release. In this tissue the inhibitory effects mediated by histamine H₃ receptors seem to be coupled, via a G protein, to a restriction of Ca²⁺ access into the nerve terminal; other mechanisms, however, have been suggested in the gastric mucosa. Histamine H₃ receptors have already been subdivided into two receptor subtypes, H_3A and H_3B, the former being the subtype predominant in the gastrointestinal tissue. The increasing availability of selective agonists and antagonists of H₃ receptors will unravel possible novel actions and physiological roles of histamine.This work was supported by a grant from the European Community (Biomed I project).     

Endothelial progenitor cells and cardiovascular homeostasis: clinical implications

Emerging evidences indicate that endothelial progenitor cells (EPCs) actively contribute in regulating cardiovascular homeostasis, and interest is growing for possible future diagnostic and therapeutic applications in the cardiovascular arena. In the present clinically-oriented review, special attention was given to the clinical implications of the potential of EPCs to test and strengthen the capacity of the organism to challenge atherosclerosis, vascular remodelling and ischemia. Accumulating data suggest that the vasculo-protective functions of EPCs may be used as cellular biomarkers for endothelial damage, or may be pharmacologically modulated to enhance the body's defence to atherosclerosis. Furthermore, biomedical engineering and cell transplantation open new scenarios to reverse vascular and graft remodelling and achieve therapeutic angiogenesis in limb and heart ischemia. However, a number of unsolved issues remain to be exploited, such as the identification of the true identity of EPCs and a better characterization of their role in vascular homeostasis under normal and pathologic conditions.     

Development of Inflammatory Angiogenesis by Local Stimulation of Fas In Vivo

Fas–Fas ligand interaction is thought to be a crucial mechanism in controlling lymphocyte expansion by inducing lymphocyte apoptosis. However, Fas is also broadly expressed on nonlymphoid cells, where its function in vivo remains to be determined. In this study, we describe the development of inflammatory angiogenesis induced by agonistic anti-Fas mAb Jo2 in a murine model where Matrigel is used as a vehicle for the delivery of mediators. The subcutaneous implants in mice of Matrigel containing mAb Jo2 became rapidly infiltrated by endothelial cells and by scattered monocytes and macrophages. After formation and canalization of new vessels, marked intravascular accumulation and extravasation of neutrophils were observed. Several mast cells were also detected in the inflammatory infiltrate. The phenomenon was dose and time dependent and required the presence of heparin. The dependency on activation of Fas is suggested by the observation that the inflammatory angiogenesis was restricted to the agonistic anti-Fas mAb and it was absent in lpr Fas-mutant mice. Apoptotic cells were not detectable at any time inside the implant or in the surrounding tissue, suggesting that angiogenesis and cell infiltration did not result from recruitment of phagocytes by apoptotic cells but rather by a stimulatory signal through Fas-engagement. These findings suggest a role for Fas–Fas ligand interaction in promoting local angiogenesis and inflammation.     

Establishment and characterization of a B-cell line derived from a patient with a myelodysplastic syndrome which expresses myelomonocytic and lymphoid markers

We describe a novel continuous B-cell line (PV-90) derived from a patient with myelodysplastic syndrome (MDS) and originating from spontaneous infection with the Epstein-Barr virus (EBV). The patient progressed to acute myeloblastic leukaemia (AML) 5 months after clinical onset of MDS. PV-90 is of clonal origin as indicated by the presence of immunoglobulin (Ig) gene rearrangements, monoclonal surface immunoglobulins, and a single DNA restriction fragment corresponding to the EBV genomic termini. PV-90 cells also express a number of myelomonocytic markers, including alpha-naphthyl acetate esterase (ANAE), coagulation factor XIII, and CD68 antigen. Moreover, PV-90 cells constitutively express the c-fms proto-oncogene mRNA as the patient's blast cells did. Whereas a trisomy 11 (+11) was found in the patient's bone marrow cells, PV-90 cells had a normal karyotype initially, but at 4 months showed two different and independent chromosomal abnormalities: 90, XX, -Y, -Y, t(9;16) (q11;p13), and 90, XX, -Y, -Y, t(17;18) (p13;q21), the latter possibly involving the p53 (17,p13) and bcl-2 (18, q21) proto-oncogenes. The early development of these chromosomal aberrations is consistent with a genetic instability of PV-90 cells. Expression of bi-lineage markers and genetic instability may suggest that PV-90 cells originated from transformation of a myelodysplastic progenitor cell capable of both myeloid and B-cell differentiation. The PV-90 cell line might be useful in a number of studies, including the possible role of c-fms in cell differentiation, pathogenetic mechanisms of human preleukaemia and lineage promiscuity in acute leukaemia.     

Choroidal thickness is associated with renal hemodynamics in essential hypertension

The choroid is the most vascularized structure of the eye and plays a central role in the development of the retinal vascular changes that occur in arterial hypertension. Changes of choroidal thickness (ChT) assessed by optical coherence tomography (OCT) technology could reflect the vascular complications of hypertension. Also, intrarenal hemodynamic damage, associated with endothelial dysfunction, demonstrated to be a good indicator of systemic morphofunctional arterial impairment. The aim of this study is to assess the relationship between ChT and renal hemodynamics in subjects with essential hypertension. Routine laboratory tests, clinical history, and physical examination, including blood pressure assessment, were performed in 90 subjects with essential hypertension. All patients underwent Doppler ultrasonographic evaluation of intra‐renal hemodynamics and OCT imaging to assess ChT. When subjects were divided in two groups based on renal resistive index (RRI), group I (RRI ≥ 75% percentile) showed significantly lower values of ChT than group II (RRI < 75% percentile) (P < .001). When divided in two groups based on the ChT median values, patients with lower ChT had significantly higher RRI values than those with ChT above the median values (P < .05). In multivariate model including age, eGFR, and other variables as confounding factors, RRI ≥ 75% was independently associated with ChT. ChT was significantly correlated with renal resistive index in subjects with essential hypertension, confirmed in multivariate analyses. This result could be referred to changes in vascular elastic properties that occur in retinal and intrarenal vascular system probably due to oxidative stress and endothelial dysfunction commonly found in early complications of hypertension.     

Periprocedural outcomes of prophylactic protamine administration for reversal of heparin after cryoballoon ablation of atrial fibrillation

Purpose

The aim of this study was to investigate the efficacy and the safety of prophylactic use of protamine in a series of heparinized patients having undergone cryoballoon (CB) ablation for atrial fibrillation (AF).

Methods

From October 2013 to January 2014, 54 consecutive patients received protamine after CB ablation to neutralize unfractionated heparin (UFH) effects. They were prospectively included in this study and compared to a control group of 53 patients who underwent CB ablation without receiving protamine.

Results

A total of 54 consecutive patients (33 male, 61 %; mean age, 58?±?12 years) were included. Twenty-one patients (39 %) presented with hypertension, 17 (31 %) with dyslipidemia, and 4 (7 %) with diabetes. Five patients (9 %) had a previous episode of ischemic stroke. Mean protamine dose was 68?±?22 mg. No adverse reaction to protamine was observed. Among patients having received protamine, one (2 %) experienced a cardiac tamponade requiring non-surgical drainage. No patient having undergone protamine administration experienced vascular complications. Conversely, the group of patients not treated with protamine had a significantly higher incidence of vascular complications as compared to patients having undergone protamine infusion (11 vs 0 %, p?=?0.01).

Conclusions

Reversing effects of UFH by the means of protamine administration appears to be safe after CB ablation for AF. It can allow in-laboratory sheath removal with potentially less vascular complications and no increase of thromboembolic risk. Larger randomized studies are needed in order to confirm our findings.     

Role of Niacin in Current Clinical Practice: A Systematic Review

Background

Niacin, a potent high-density lipoprotein cholesterol-raising drug, seems an attractive approach to reduce cardiac events in patients with or at risk of atherosclerotic cardiovascular disease. However, previous evidence for niacin has been challenged recently by negative outcomes in 2 large, randomized, controlled trials comparing niacin to placebo with background statin therapy. We studied the currently available evidence for the role of niacin treatment for reducing the risk of cardiovascular events in current practice.

The comparison of effects of biologic agents on rheumatoid arthritis damage progression is biased by period of enrolment: Data from a systematic review and meta-analysis

Objectives

To indirectly compare the 12-month effects of available biologic agents in slowing RA radiographic progression.

Methods

A systematic review of literature of randomised, double-blind, controlled trials (RCTs) evaluating RA radiographic progression as end point was conducted using a PubMed searching of MEDLINE from January 1995 to May 2012. For each trial, the mean change from baseline of the standardised annual radiographic progression score (weighted for estimated annual progression rate) was estimated, and the effect size was calculated as the difference between biologic and non-biologic-treated groups. In order to optimise data homogeneity and improve RCTs comparison, a mixed-effect model was applied including previous responsiveness to methotrexate (MTX-experienced or MTX-naïve populations) and period of study enrolment as moderators.

Results

The PubMed search resulted in 183 references, and 14 were eligible for the meta-analysis. The analysis of study distribution in forest plots showed a high correlation between the study period of enrolment and the impact of biological therapy in both MTX-naïve and MTX-experienced subgroups. In particular, effect size was the highest for older trials and progressively decreased in the most recent ones, suggesting a highest propensity to radiographic progression in populations enroled in older trials. Some statistically significant differences among RCTs were found in both subgroups but were significantly biased by the different propensity to radiographic progression due to period of enrolment.

Conclusions

Our meta-analysis demonstrated that period of enrolment deeply influence study population propensity to radiographic progression in each trial. This finding does not allow the indirect comparison of various biologic agents, despite our mixed-model significantly reducing heterogeneity among RCTs.     

Expanding the natural history of nonalcoholic steatohepatitis: from cryptogenic cirrhosis to hepatocellular carcinoma

BACKGROUND & AIMS: Nonalcoholic steatohepatitis (NASH) may progress to cirrhosis; whether NASH plays also a role in the development of hepatocellular carcinoma (HCC) is unknown. METHODS: Among 641 cirrhosis-associated HCCs, we retrospectively identified 44 patients with cryptogenic cirrhosis (CC). Of these, 23 were actively followed up and were compared in a case-control study with viral- and alcohol-associated HCC. Family and personal history of diabetes, hypertension, coronary heart disease, dyslipidemia, obesity, and biochemical data were compared between groups. Iron status and presence of mutations in the HFE gene of familiar hemochromatosis were also determined. RESULTS: Family history was not different in relation to etiology. The prevalence of obesity and diabetes was significantly higher in patients with CC. Although liver function was similar, CC patients had higher glucose, cholesterol, and triglyceride plasma levels, increased parameters of insulin resistance, and lower aminotransferase levels. Iron status and prevalence of mutations in the HFE gene did not differ. Logistic regression analysis identified in sequence hypertriglyceridemia, diabetes, and normal aminotransferases as independent factors associated with HCC arising in CC. CONCLUSIONS: Features suggestive of NASH are more frequently observed in HCC arising in patients with CC than in age- and sex-matched HCC patients of well-defined viral or alcoholic etiology. HCC may represent a late complication of NASH-related cirrhosis.     

The incidence of venous thromboembolism in thrombophilic children: a prospective cohort study

Antithrombin and protein C and S defects, factor V Leiden mutation, and G20210A prothrombin gene mutation are well-recognized risk factors for venous thromboembolism (VTE) in adults, especially during circumstantial situations such as trauma, immobilization, surgery, or oral contraceptive treatment. The relevance of these defects in predisposing children to VTE is still undefined. In a prospective cohort study we assessed the incidence of spontaneous and risk period-related VTE in asymptomatic children (aged 1-14 years), who were family members of a proband with an objectively diagnosed venous thromboembolic event and a documented single thrombophilic abnormality. We enrolled 143 children from 63 families. Of them, 81 (56.6%) were carriers of an inherited defect, whereas the remaining 62 were free from known genetic or acquired causes of thrombophilia. The mean observation period was 5 years (range, 1-8 years) in each group. Thirty-one risk periods occurred in the carriers group and 20 in noncarriers. Neither spontaneous nor risk period-related VTE occurred in either group during 395 and 296 observation years, respectively. However, circumstances where most of the pediatric thromboses occur (insertion of central venous lines, cancer, and cardiovascular surgery) were not encountered. In conclusion, the thrombotic risk in otherwise healthy children with a single identified thrombophilic defect appears to be very low. Common triggering conditions for VTE in thrombophilic adults do not seem to increase the thrombotic risk in children carrying the same inherited defect. Accordingly, screening for thrombophilia in otherwise healthy children younger than 15 years who belong to families with inherited defects predisposing to thrombosis seems unjustified.