Effect of histamine-receptor antagonism on the circulating inflammatory cell and cytokine response to exercise: A pilot study

The purpose of this study was to gain insight into histamine's role in the exercise inflammatory response and recovery from exercise. To explore this, young healthy participants (n = 12) performed 300 eccentric leg extensions under control (Placebo) versus histamine H1 and H2 receptor antagonism (Blockade) in a randomized cross-over study. Circulating leukocytes and cytokines were measured for 72 h after exercise. Circulating leukocytes were elevated at 6 and 12 h after exercise (p < 0.05) with the peak response being a 44.1 ± 11.7% increase with Blockade versus 13.7 ± 6.6% with Placebo (both p < 0.05 vs. baseline, but also p < 0.05 between Blockade and Placebo). Of the cytokines that were measured, only MCP-1 was elevated following exercise. The response at 6 h post-exercise was a 104.0 ± 72.5% increase with Blockade versus 93.1 ± 41.9% with Placebo (both p < 0.05 vs. baseline, p = 0.82 between Blockade and Placebo). The main findings of the present investigation were that taking combined histamine H1 and H2 receptor antagonists augmented the magnitude but not the duration of the increase of circulating immune cells following exercise. This suggests histamine is not only exerting a local influence within the skeletal muscle but that it may influence the systemic inflammatory patterns.

Acid-suppressive drugs: A systematic review and network meta-analysis of their nocturnal acid-inhibitory effect

BACKGROUND AND AIMS

Acid-suppressive drugs (ASDs) are widely used in many gastric acid-associated diseases. Nocturnal acid breakthrough has been a common problem of many ASDs, such as proton-pump inhibitors (PPIs) and H2 -receptor antagonists (H2RAs). Potassium-competitive acid blockers (P-CABs) are expected to solve this continuing conundrum. This article examined major ASDs and compared them with placebo in terms of nocturnal acid-inhibitory effects, using a network meta-analysis of randomized controlled trials (RCTs).

METHODS

To compare the effectiveness of major ASDs, a Bayesian network meta-analysis (NMA) was applied to process data extracted from RCTs. The plausible ranking for each regimen and some subgroups were assessed by surface under the cumulative ranking curves (SUCRA).

RESULTS

Fifty-five RCTs were conducted with 2015 participants. In terms of nocturnal acid-inhibitory effects, the overall results showed that tegoprazan (SUCRA 91.8%) and vonoprazan (SUCRA 91.0%) had the best performance, followed by new PPIs (including tenatoprazole and ilaprazole) (SUCRA 76.6%), additional H2RAs once at bedtime (AHB) (SUCRA 61.3%), isomer PPIs (including esomeprazole and dexlansoprazole) (SUCRA 38.6%), revaprazan (SUCRA 34.7%), traditional PPIs (including omeprazole, rabeprazole, pantoprazole, lansoprazole) (SUCRA 32.6%), H2RAs (SUCRA 23.1%), and placebo (SUCRA 0.3%). In some subgroups, the nocturnal acid-inhibitory effect of vonoprazan or tegoprazan was better than most of the other regimens, even new PPIs and AHB.

CONCLUSIONS

This is the first study to compare the effect of ASDs on inhibiting nocturnal acid breakthrough. Overall, in terms of nocturnal acid-inhibitory effect, vonoprazan and tegoprazan had an advantage against other regimens including H2RAs, isomer PPIs, traditional PPIs, AHB, and new PPIs. Even in some subgroups, such as language classification (English), types of study design (crossover-RCT), age (≤40 years), BMI (18.5-24.9 kg/m2 ), continent (Asia and North America), disease status (health), the duration of therapy (2 weeks), and time of administration (at daytime or at night-time), the nocturnal acid-inhibitory effect of vonoprazan or tegoprazan were better than most regimens, even AHB and new PPIs.

Effect of proton pump inhibitors and H2 antagonists on gastric wall uptake in myocardial perfusion scan with 99mTc-sestamibi

BACKGROUND

Proton pump inhibitors (PPIs) have been speculated to cause gastric wall uptake (GWU) in MPI scans. However, the uptake mechanism and prevention methods are less studied. In this prospective trial we aimed to evaluate the impact of gastroprotective medications on GWU and its solutions.

METHODS

351 consecutive patients, scheduled for 2-day rest/stress 99mTc-MIBI scan, were distributed into 5 groups. 3-7 days following the baseline rest scan, the stress scan was acquired after intervention in the trial group, consisting of patients with history of PPI intake, randomly assigned to 3 subgroups: discontinuing PPIs(A), replacement with H2 blockers (B), and continuing PPIs (C). Patients receiving H2 blockers, continued it as before (D) and the remaining patients were the control group (E). GWU was graded compared to the myocardial uptake.

RESULTS

In the rest phase, all groups had significantly higher GWU compared to the control group. In the stress phase, group A had less GWU than group B (P-value < 0.05) and both of them had significantly less GWU compared to group C (P-value < 0.001). There was no significant difference between PPI discontinuation periods of 3-5 days versus 5-7 days. There was a significant association between duration of oral PPI intake, but not IV PPIs, and GWU. GWU was significantly lower with oral compared to IV PPI administration.

CONCLUSION

PPIs significantly increase GWU and discontinuing them for at least 3-5 days significantly reduces GWU. H2 antagonists are a good alternative in patients who cannot tolerate dyspepsia symptoms.

Molecular basis for the repurposing of histamine H2-receptor antagonist to treat COVID-19

With the world threatened by a second surge in the number of Coronavirus cases, there is an urgent need for the development of effective treatment for the novel coronavirus (COVID-19). Recently, global attention has turned to preliminary reports on the promising anti-COVID-19 effect of histamine H2-receptor antagonists (H2RAs), most especially Famotidine. Therefore, this study was designed to exploit a possible molecular basis for the efficacy of H2RAs against coronavirus. Molecular docking was performed between four H2RAs, Cimetidine, Famotidine, Nizatidine, Ranitidine, and three non-structural proteins viz. NSP3, NSP7/8 complex, and NSP9. Thereafter, a 100 ns molecular dynamics simulation was carried out with the most outstanding ligands to determine the stability. Thereafter, Famotidine and Cimetidine were subjected to gene target prediction analysis using HitPickV2 and eXpression2Kinases server to determine the possible network of genes associated with their anti-COVID activities. Results obtained from molecular docking showed the superiority of Famotidine and Cimetidine compared to other H2RAs with a higher binding affinity to all selected targets. Molecular dynamic simulation and MMPBSA results revealed that Famotidine as well as Cimetidine bind to non-structural proteins more efficiently with high stability over 100 ns. Results obtained suggest that Famotidine and Cimetidine could be a viable option to treat COVID-19 with a mechanism of action that involves the inhibition of viral replication through the inhibition of non-structural proteins. Therefore, Famotidineand Cimetidine qualify for further study as a potential treatment for COVID-19.

Influence of Proton Pump Inhibitors and Histamine Receptor 2 Antagonists on Blastocystis ST3 and Selected Microorganisms of Intestinal Microbiota In Vitro

INTRODUCTION

Proton pump inhibitors (PPIs) and histamine receptor 2 (H2) antagonists are commonly prescribed medications. Association between PPIs and alteration of the gut microbiota has been reported. Blastocystis, the most common intestinal protozoan worldwide, occurs in both healthy and symptomatic people with gastrointestinal or cutaneous disorders, with controversial pathogenicity. The current study was aimed to investigate the influence of PPIs and H2 blockers on the in vitro proliferation of selected intestinal bacteria, fungi, and protozoa.

METHODS

Cultures of Lactobacillus rhamnosus, Escherichia coli, Enterococcus faecium, Candida albicans, and Blastocystis subtype 3 were treated with different concentrations of respective medications in vitro, and the numbers of microorganisms were quantified and compared.

RESULTS

Pantoprazole and esomeprazole exerted a significant inhibition on Blastocystis and C. albicans, especially at higher concentrations, which were even more effective than metronidazole. On the other hand, treatment with pantoprazole caused an increase in proliferation of L. rhamnosus and E. coli. There was no influence of H2 blockers on the examined microorganisms.

DISCUSSION

PPIs, such as pantoprazole, can be a potential treatment in the prophylaxis or eradication of Blastocystis and C. albicans.

Molecular Background, Clinical Features and Management of Pediatric Mastocytosis: Status 2021

Pediatric mastocytosis is a heterogeneous disease characterized by accumulation of mast cells in the skin and less frequently in other organs. Somatic or germline mutations in the KIT proto-oncogene are detected in most patients. Cutaneous mastocytosis is the most common form of the disease in children. In the majority of cases, skin lesions regress spontaneously around puberty. However, in few patients, mastocytosis is not a self-limiting disease, but persists into adulthood and can show signs of systemic involvement, especially when skin lesions are small-sized and monomorphic. Children with mastocytosis often suffer from mast cell mediator-related symptoms. Severe hypersensitivity reactions can also occur, mostly in patients with extensive skin lesions and blistering. In a substantial number of these cases, the triggering factor of anaphylaxis remains unidentified. Management of pediatric mastocytosis is mainly based on strict avoidance of triggers, treatment with H1 and H2 histamine receptor blockers, and equipment of patients and their families with epinephrine auto-injectors for use in severe anaphylactic reactions. Advanced systemic mastocytosis occurs occasionally. All children with mastocytosis require follow-up examinations. A bone marrow investigation is performed when advanced systemic mastocytosis is suspected and has an impact on therapy or when cutaneous disease persists into adulthood.

Histamine H1 receptor antagonists selectively kill cisplatin-resistant human cancer cells

Cancer therapy is often hampered by the disease's development of resistance to anticancer drugs. We previously showed that the autonomously upregulated product of fibroblast growth factor 13 gene (FGF13; also known as FGF homologous factor 2 (FHF2)) is responsible for the cisplatin resistance of HeLa cisR cells and that it is likely responsible for the poor prognosis of cervical cancer patients treated with cisplatin. Here we show that cloperastine and two other histamine H1 receptor antagonists selectively kill HeLa cisR cells at concentrations that little affect parental HeLa S cells. The sensitivity of HeLa cisR cells to cloperastine was abolished by knocking down FGF13 expression. Cisplatin-resistant A549 cisR cells were similarly susceptible to cloperastine. H2, H3, and H4 receptor antagonists showed less or no cytotoxicity toward HeLa cisR or A549 cisR cells. These results indicate that histamine H1 receptor antagonists selectively kill cisplatin-resistant human cancer cells and suggest that this effect is exerted through a molecular mechanism involving autocrine histamine activity and high-level expression of FGF13. We think this represents a potential opportunity to utilize H1 receptor antagonists in combination with anticancer agents to treat cancers in which emergent drug-resistance is preventing effective treatment.

Efficacy and safety of gastrointestinal bleeding prophylaxis in critically ill patients: systematic review and network meta-analysis

OBJECTIVE

To determine, in critically ill patients, the relative impact of proton pump inhibitors (PPIs), histamine-2 receptor antagonists (H2RAs), sucralfate, or no gastrointestinal bleeding prophylaxis (or stress ulcer prophylaxis) on outcomes important to patients.

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

Medline, PubMed, Embase, Cochrane Central Register of Controlled Trials, trial registers, and grey literature up to March 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES AND METHODS

We included randomised controlled trials that compared gastrointestinal bleeding prophylaxis with PPIs, H2RAs, or sucralfate versus one another or placebo or no prophylaxis in adult critically ill patients. Two reviewers independently screened studies for eligibility, extracted data, and assessed risk of bias. A parallel guideline committee (BMJ Rapid Recommendation) provided critical oversight of the systematic review, including identifying outcomes important to patients. We performed random-effects pairwise and network meta-analyses and used GRADE to assess certainty of evidence for each outcome. When results differed between low risk and high risk of bias studies, we used the former as best estimates.

RESULTS

Seventy two trials including 12 660 patients proved eligible. For patients at highest risk (>8%) or high risk (4-8%) of bleeding, both PPIs and H2RAs probably reduce clinically important gastrointestinal bleeding compared with placebo or no prophylaxis (odds ratio for PPIs 0.61 (95% confidence interval 0.42 to 0.89), 3.3% fewer for highest risk and 2.3% fewer for high risk patients, moderate certainty; odds ratio for H2RAs 0.46 (0.27 to 0.79), 4.6% fewer for highest risk and 3.1% fewer for high risk patients, moderate certainty). Both may increase the risk of pneumonia compared with no prophylaxis (odds ratio for PPIs 1.39 (0.98 to 2.10), 5.0% more, low certainty; odds ratio for H2RAs 1.26 (0.89 to 1.85), 3.4% more, low certainty). It is likely that neither affect mortality (PPIs 1.06 (0.90 to 1.28), 1.3% more, moderate certainty; H2RAs 0.96 (0.79 to 1.19), 0.9% fewer, moderate certainty). Otherwise, results provided no support for any affect on mortality, Clostridium difficile infection, length of intensive care stay, length of hospital stay, or duration of mechanical ventilation (varying certainty of evidence).

CONCLUSIONS

For higher risk critically ill patients, PPIs and H2RAs likely result in important reductions in gastrointestinal bleeding compared with no prophylaxis; for patients at low risk, the reduction in bleeding may be unimportant. Both PPIs and H2RAs may result in important increases in pneumonia. Variable quality evidence suggested no important effects of interventions on mortality or other in-hospital morbidity outcomes.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019126656.

An Herbal H2 Blocker in Melasma Treatment

BACKGROUND

Melasma is a skin pigmentation disorder that remains resistant to available therapies. The exact cause of melasma is unknown. Histamine is an inflammatory factor. Its involvement in pigmentation is obscure. The aim of this study is to introduce an herbal antihistamine H2 receptor which is effective in these disorders.

METHODS

This is a review study by searching the electronic databases and also Persian Medicine books, from 2000 to 2018 by the keywords such as H2 antagonist, H2 blocker and melasma.

RESULTS

According to the researched studies, histamine can induce melanogenesis and melasma after a series of stages in the body. Also, Histamine, through receptors 2, triggers melasma. Therefore, it can be said that antihistamine H2 receptor can be effective in melasma. Considering chemical antihistamine, H2 receptors have side effects, such as digestive problems, H2 antagonists can be used in the treatment of diseases such as dyspepsia but they have multiple complications. On the other hand, there is an herbal H2 antagonist that can be useful for melasma due to having some special properties.

CONCLUSION

Herbal H2 blockers should be noted in melasma treatment along with the topical drugs.

Blocking H1/H2 histamine receptors inhibits damage/fibrosis in Mdr2-/- mice and human cholangiocarcinoma tumorigenesis

Primary sclerosing cholangitis (PSC) patients are at risk of developing cholangiocarcinoma (CCA). We have shown that (1) histamine increases biliary hyperplasia through H1/H2 histamine receptors (HRs) and (2) histamine levels increase and mast cells (MCs) infiltrate during PSC and CCA. We examined the effects of chronic treatment with H1/H2HR antagonists on PSC and CCA. Wild-type and multidrug-resistant knockout (Mdr2-/- ) mice were treated by osmotic minipumps with saline, mepyramine, or ranitidine (10 mg/kg body weight/day) or a combination of mepyramine/ranitidine for 4 weeks. Liver damage was assessed by hematoxylin and eosin. We evaluated (1) H1/H2HR expression, (2) MC presence, (3) L-histidine decarboxylase/histamine axis, (4) cholangiocyte proliferation/bile duct mass, and (5) fibrosis/hepatic stellate cell activation. Nu/nu mice were implanted with Mz-ChA-1 cells into the hind flanks and treated with saline, mepyramine, or ranitidine. Tumor growth was measured, and (1) H1/H2HR expression, (2) proliferation, (3) MC activation, (4) angiogenesis, and (5) epithelial-mesenchymal transition (EMT) were evaluated. In vitro, human hepatic stellate cells were evaluated for H1HR and H2HR expression. Cultured cholangiocytes and CCA lines were treated with saline, mepyramine, or ranitidine (25 μM) before evaluating proliferation, angiogenesis, EMT, and potential signaling mechanisms. H1/H2HR and MC presence increased in human PSC and CCA. In H1/H2HR antagonist (alone or in combination)-treated Mdr2-/- mice, liver and biliary damage and fibrosis decreased compared to saline treatment. H1/H2HR antagonists decreased tumor growth, serum histamine, angiogenesis, and EMT. In vitro, H1/H2HR blockers reduced biliary proliferation, and CCA cells had decreased proliferation, angiogenesis, EMT, and migration. Conclusion: Inhibition of H1/H2HR reverses PSC-associated damage and decreases CCA growth, angiogenesis, and EMT; because PSC patients are at risk of developing CCA, using HR blockers may be therapeutic for these diseases. (Hepatology 2018).

Lafutidine, a histamine H2 receptor antagonist with mucosal protective properties, attenuates 5-fluorouracil-induced intestinal mucositis in mice through activation of extrinsic primary afferent neurons

Intestinal mucositis accompanied by severe diarrhea is one of the most common side effects during cancer chemotherapy. Lafutidine, a histamine H2 receptor antagonist with mucosal protective properties via sensory afferent neurons, is used for the treatment of upper gastrointestinal diseases. The present study investigated the effects of lafutidine on 5-fluorouracil (5-FU)-induced intestinal mucositis induced in mice. Male C57BL/6 wild-type (WT), sensory deafferented mice, and transient receptor potential vanilloid subfamily 1 knockout (TRPV1KO) mice were used. Animals were administered 5-FU once daily, while lafutidine and famotidine were administered twice daily for 6 days. Repeated administration of 5-FU caused severe intestinal mucositis, characterized by shortening of villi and destruction of crypts and was accompanied by diarrhea and body weight loss. Daily administration of lafutidine reduced the severity of intestinal mucositis, diarrhea and body weight loss in a dose-dependent manner, while famotidine had no effect on intestinal mucositis. The preventive effects of lafutidine were completely abolished in sensory deafferented and TRPV1-KO mice. Lafutidine significantly suppressed 5-FU-increased MPO activity and inflammatory cytokine expression on day 6, but not apoptosis induction in intestinal crypts on day 1. Lafutidine induced Alcian Blue and PAS-positive mucus production in the small intestine. These findings suggest that lafutidine attenuates 5-FU-induced intestinal mucositis, most likely by increasing mucus production via activation of sensory afferent neurons. Furthermore, intact TRPV1 signaling is essential for the activation of sensory afferent neurons induced by lafutidine. Therefore, lafutidine is more useful than other common antacids for the treatment of intestinal mucositis during cancer chemotherapy.

[Mechanisms of histamine ameliorating memory impairment induced by pentylenetetrazole-kindling epilepsy in rats]

Objective: To investigate the effects of neuronal histamine on spatial memory acquisition impairment in rats with pentylenetetrazole-kindling epilepsy, and to explore its mechanisms. Methods: A subconvulsive dose of pentylenetetrazole (35 mg/kg) was intraperitoneally injected in rats every 48 h to induce chemical kindling until fully kindled. Morris water maze was used to measure the spatial memory acquisition of the rats one week after fully pentylenetetrazole-kindled, and the histamine contents in different brain areas were measured spectrofluorometrically. Different dosages of hitidine (the precursor of histamine), pyrilamine (H1 receptor antagonist), and zolantidine (H2 receptor antagonist) were intraperitoneally injected, and their effects on spatial memory acquisition of the rats were observed. Results: Compared with control group, escape latencies were significantly prolonged on Morris water maze training day 2 and day 3 in pentylenetetrazole-kindling epilepsy rats (all P<0.05); and the histamine contents in hippocampus, thalamus and hypothalamus were decreased significantly (all P<0.05). Escape latencies were markedly shortened on day 3 by intraperitoneally injected with histidine 500 mg/kg, and on day 2 and day 3 by intraperitoneally injected with histidine 1000 mg/kg in pentylenetetrazole-kindling epilepsy rats (all P<0.05). The protection of histidine was reversed by zolantidine (10 and 20 mg/kg), but not by pyrilamine. Conclusion: Neuronal histamine can improve the spatial memory acquisition impairment in rats with pentylenetetrazole-kindling epilepsy, and the activation of H2 receptors is possibly involved in the protective effects of histamine.

Use of Histamine2-Antagonists for the Treatment of Verruca Vulgaris

Objective:

To review the evidence for histamine2 (H2)-antagonists in the treatment of common warts.

Data Sources:

Relevant publications were identified through a systematic search of PubMed English-language literature using the MeSH terms and key words cimetidine, ranitidine, famotidine, nizatidine, histamine H2-antagonists, and warts. Additional articles were identified using the same key words in the Cochrane Database and International Pharmaceutical Abstracts. Systematic searches were conducted through January 2007. In addition, pertinent references from identified articles were reviewed.

Study Selection and Data Extraction:

The literature search retrieved 21 relevant citations, excluding review articles. Five open-label studies and 7 randomized controlled clinical trials were evaluated. Cimetidine was the focus of 11 studies, and ranitidine was evaluated in 1 study. No data regarding the other H2-antagonists were found. The other retrieved citations were not evaluated due to their design (case reports or case series) and/or focus on specific wart subtypes, not common warts.

Data Synthesis:

The use of H2-antagonists in the treatment of common warts is not associated with significant improvements in resolution rates. Open-label studies were promising with an estimated 48–81% response rate. However, randomized controlled trials have failed to show significant efficacy when cimetidine was compared with placebo or topical agents, and ranitidine has never been evaluated in a randomized controlled trial. Adverse effects, specifically gastrointestinal complaints, were documented. Efficacy may have been limited by inadequate dosing in some of the trials. The studies were limited by the small sample size and lack of power in a number of the trials, as well as the documented spontaneous resolution rate for warts.

Conclusions:

Several open-label trials evaluating the use of H2-antagonists for verruca vulgaris reported high response rates, but these results have not been corroborated by more rigorous clinical trials. Current data do not support the use of H2-antagonisis for the treatment of common warts.

An Evaluation of the Antihistamine Activity of Acrivastine and Its Onset in Human Skin

In a double-blind, two-period crossover study, 24 healthy volunteers were evaluated to establish the time of onset of action of activity of acrivastine in suppressing the weal and flare response to intradermally injected histamine. Volunteers received single doses of 8 mg acrivastine and placebo according to a fully randomized, balanced treatment plan. Acrivastine significantly ( P < 0.002) reduced the flare response induced by 0.4 μg histamine challenge 15 min after oral acrivastine dosing when compared with placebo. A significant ( P < 0.001) reduction of the weal response was noted at 25 min, although trends in this direction were already present at earlier time points.

Dans d'une étude croisée à deux phase, réalisée en double aveugle et ayant porté sur 24 volontaires sains, on a tenté d'établir le moment du début de l'action de l'acrivastine dans la suppression de la réponse inflammatoire consécutive à l'injection intradermique d'histamine. Les volontaires ont reçu des doses uniques de 8 mg d'acrivastine et de placebo, selon un plan de traitement entièrement randomisé et équilibré. L'acrivastine a réduit significativement ( P < 0,002) la réponse de rubéfaction induite par 0,4 μg d'histamine 15 minutes après l'administration orale d'acrivastine, par rapport au placebo. Une réduction significative ( P < 0,001) de la réponse d'enflure a été notée à 25 minutes, bien qu'une tendance en ce sens ait déjà été observée à un stade plus précoce.

Efficacy and safety of proton pump inhibitors for stress ulcer prophylaxis in critically ill patients: a systematic review and meta-analysis of randomized trials

BACKGROUND

The relative efficacy and safety of proton pump inhibitors (PPIs) compared to histamine-2-receptor antagonists (H2RAs) should guide their use in reducing bleeding risk in the critically ill.

METHODS

We searched the Cochrane library, MEDLINE, EMBASE, ACPJC, clinical trials registries, and conference proceedings through November 2015 without language or publication date restrictions. Only randomized controlled trials (RCTs) of PPIs vs H2RAs for stress ulcer prophylaxis in critically ill adults for clinically important bleeding, overt gastrointestinal (GI) bleeding, nosocomial pneumonia, mortality, ICU length of stay and Clostridium difficile infection were included. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess our confidence in the evidence for each outcome.

RESULTS

In 19 trials enrolling 2117 patients, PPIs were more effective than H2RAs in reducing the risk of clinically important GI bleeding (RR 0.39; 95 % CI 0.21, 0.71; P = 0.002; I (2) = 0 %, moderate confidence) and overt GI bleeding (RR 0.48; 95 % CI 0.34, 0.66; P < 0.0001; I (2) = 3 %, moderate confidence). PPI use did not significantly affect risk of pneumonia (RR 1.12; 95 % CI 0.86, 1.46; P = 0.39; I (2) = 2 %, low confidence), mortality (RR 1.05; 95 % CI 0.87, 1.27; P = 0.61; I (2) = 0 %, moderate confidence), or ICU length of stay (mean difference (MD), -0.38 days; 95 % CI -1.49, 0.74; P = 0.51; I (2) = 30 %, low confidence). No RCT reported Clostridium difficile infection.

CONCLUSIONS

PPIs were superior to H2RAs in preventing clinically important and overt GI bleeding, without significantly increasing the risk of pneumonia or mortality. Their impact on Clostridium difficile infection is yet to be determined.

Histamine 1 Receptor Blockade Enhances Eosinophil-Mediated Clearance of Adult Filarial Worms

Filariae are tissue-invasive nematodes that cause diseases such as elephantiasis and river blindness. The goal of this study was to characterize the role of histamine during Litomosoides sigmodontis infection of BALB/c mice, a murine model of filariasis. Time course studies demonstrated that while expression of histidine decarboxylase mRNA increases throughout 12 weeks of infection, serum levels of histamine exhibit two peaks—one 30 minutes after primary infection and one 8 weeks later. Interestingly, mice treated with fexofenadine, a histamine receptor 1 inhibitor, demonstrated significantly reduced worm burden in infected mice compared to untreated infected controls. Although fexofenadine-treated mice had decreased antigen-specific IgE levels as well as lower splenocyte IL-5 and IFNγ production, they exhibited a greater than fourfold rise in eosinophil numbers at the tissue site where adult L. sigmodontis worms reside. Fexofenadine-mediated clearance of L. sigmodontis worms was dependent on host eosinophils, as fexofenadine did not decrease worm burdens in eosinophil-deficient dblGATA mice. These findings suggest that histamine release induced by tissue invasive helminths may aid parasite survival by diminishing eosinophilic responses. Further, these results raise the possibility that combining H1 receptor inhibitors with current anthelmintics may improve treatment efficacy for filariae and other tissue-invasive helminths.

Filariae are tissue-invasive parasitic roundworms that infect over 100 million people worldwide and cause debilitating conditions such as river blindness and elephantiasis. One of the major factors limiting our ability to eliminate these infections is the lack of drugs that kill adult worms when given as a short course therapy. Additionally, the mechanisms by which adult worms are cleared from infected individuals remains poorly understood. In this study, we demonstrate that treatment of infected mice with fexofenadine, an inhibitor of histamine receptor 1, significantly reduces adult worm numbers through a mechanism dependent on host eosinophils. These findings suggest that histamine release induced by parasitic worms may aid parasite survival by decreasing eosinophilic responses. Further, as antihistamines are generally safe medications, these results raise the possibility that antihistamine therapy may be useful either alone, or potentially in combination with other antifilarial medications such as diethylcarbamazine (DEC), to eliminate adult filarial worms from infected individuals.

Enhancing effect of cimetidine on peroxidase activity of human erythrocyte hemoglobin

BACKGROUND

Hemoglobin is released to the serum after erythrocyte lyses. Haptoglobin is responsible for carrying hemoglobin into the serum. In hemolytic disease, the amount of hemoglobin which is released to the serum is high; however, the amount of haptoglobin is not enough for binding all the released hemoglobins. Free hemoglobin has peroxidase activity (a pseudoenzyme) and has been indicated to be harmful for patients. This study is focused on the effect of cimetidine on peroxidase activity of hemoglobin.

METHODS

Erythrocytes were lysed to obtain hemoglobin. Peroxidase activity of hemoglobin was detected using o-dianisidine and H(2)O(2) as substrates.

RESULTS

Our results showed that the drug operated as an activator for the pseudoenzyme. Cimetidine bound to the pseudoperoxidase in an un-competitive manner and decreased the Km. Half maximal effective concentration (EC(50)) of cimetidine was determined to be about 12.5 mM. Alkaline pH increased the rate of reaction. Arrhenius plot showed that the activation energies of reactions in the absence and presence of drug were about 10.5 kJ/mol and 7.65 kJ/mol, respectively.

CONCLUSIONS

The results demonstrated that cimetidine activates the peroxidase activity of free hemoglobin. Hence, it is suggested that the prescription of cimetidine for the patients with hemolyses diseases may enhance the harmful effects of free hemoglobin in these patients.

Enhanced histamine H2 excitation of striatal cholinergic interneurons in L-DOPA-induced dyskinesia

Levodopa is the most effective therapy for the motor deficits of Parkinson's disease (PD), but long term treatment leads to the development of L-DOPA-induced dyskinesia (LID). Our previous studies indicate enhanced excitability of striatal cholinergic interneurons (ChIs) in mice expressing LID and reduction of LID when ChIs are selectively ablated. Recent gene expression analysis indicates that stimulatory H2 histamine receptors are prefentially expressed on ChIs at high levels in the striatum, and we tested whether a change in H2 receptor function might contribute to the elevated excitability in LID. Using two different mouse models of PD (6-hydroxydopamine lesion and Pitx3^ak/ak mutation), we chronically treated the animals with either vehicle or L-DOPA to induce dyskinesia. Electrophysiological recordings indicate that histamine H2 receptor-mediated excitation of striatal ChIs is enhanced in mice expressing LID. Additionally, H2 receptor blockade by systemic administration of famotidine decreases behavioral LID expression in dyskinetic animals. These findings suggest that ChIs undergo a pathological change in LID with respect to histaminergic neurotransmission. The hypercholinergic striatum associated with LID may be dampened by inhibition of H2 histaminergic neurotransmission. This study also provides a proof of principle of utilizing selective gene expression data for cell-type-specific modulation of neuronal activity.

New insight into oseophageal injury and protection in physiologically relevant animal models

Chronic diseases of lifestyle (CDL), the most common chronic group of non-infectious and non-transmissible diseases worldwide, which share the similar risk factors of unhealthy lifestyle, have become most recognized as a serious trigger in the genesis of oesophageal injury. Non-erosive oesophageal lesions (NEOL) are found more frequently than erosive or ulcer lesions in patients with reflux oesophagitis (RO) related to CDL. They also have restricted healing options, which often leads to carcinogenesis. Therefore, developing a physiologically relevant animal model of NEOL remains an urgent priority. One of triggers of CDL, postprandial hyperglycemia (PHG), which is characterized by hyperglycemic spikes, and overloading nitro-compounds leading to oxidative stress that may predispose to NEOL. The present study was designed to set up a model of RO related to CDL in rodents to understand mechanisms of oesophageal preulcerogenic injury under such conditions as food-associated long-term PHG, restrained water-immersion stress (WIS), and imbalance of entero-salivary nitrites recirculation (ESNR). Beneficial effects of L-tryptophan (L-Try) have already been described by many activities in kynurenine and melatonin (Mel) synthesis, redox reactions, which play a key role for cytoprotection and proliferation. Nevertheless, the effect of L-Try and Mel on NEOL under PHG is still unknown. An extract of Cucurbita maxim sweet seed (eCMS), which contains a high amount of antioxidants, also appear to play an important role in foregut cytoprotection. Thus, the second aim was to observe the effects of eCSE on oesophageal mucosa (OEM) in modification of ESNR (mESNR). Rats were used with without/with pre-treatment L-Try, Mel during WIS and PHG. In the second series of experiments rats were used with without/with CSE pre-treatment in mESNR; oral and OEM lesions were determined by histology; inflammation of OEM by lectin histochemistry; esophageal NO2(-), cNOS and iNOS via bioassays; interleukin 1β (IL-1β), interleukin-8 (IL-8) via ELISA. PHG caused destructive lesions in the OEM accompanied by the up-regulation of iNOS and down-regulation of cNOS expressions, excessive NO2(-) while COX significantly aggravated the severity of these lesions; L-Try prevented ulcerogenic response to PHG with potent up-regulation of cNOS but did not affect synthesis NO2(-). Mannose (Man)-containing specific a-DMan glycoconjugates labelled by lectins GNA, PSL, LCA, ConA and fucose (Fuc)-rich Fuc-α1 glycoconjugates - PFA, LABA are contributed in OEM integrity. It was shown that the changes of subepithelial and epithelial structures labelled by GNA, PSL, LCA displayed their highest exposure in the surface layer, whereas in the intima of microvasculature and nerve fibres of serosa membrane of the oesophagus by ConA during PHG NEOL. Also, the overexpression of Fuc glycans was present in OEM pre-epithelial and epithelial layers labelled by LABA and in the epithelial-glial-endothelial activity by PFA. Thus, initial changes in endothelial metabolism via iNOS and eNOS can be diagnostic and prognostic markers of NEOL in RO. Our mESNR studies also documented an early increase in pro-inflammatory mediators in the initial stage of oesophageal ulcerogenesis and repair and it can be a model for both proximal and distal oesophageal reflux diseases, as determinate by NEOL in oral mucosa and OEM. These findings suggest that endothelial metabolism is deeply involved in pathogenesis of NEOL. These models may be useful for detecting a new therapeutic strategy NERD, testing anti-ulcer drugs against RO and impaired healing OEM. Our results suggest that L-Try and Mel prevent OEM damage inducted by PHG and oesophagoprotective effect via modulation NO/NOS activity. The anti-inflammatory effect of eCMS could be used to protect oral mucosa and OEM against mESNR.

Expression of NADPH-d in the vagal nuclei of the chronic esophagitis model in rats

AIM

To evaluate the changes in the number of NADPH diaphorase (NADPH-d) stained neurons in the vagal nuclei in a chronic esophagitis model.

MATERIALS AND METHODS

There were 3 groups of rats examined: 1) a chronic gastroesophageal reflux rat group, which was created by a partial gastric outlet obstruction; 2) a sham group; and 3) a ranitidine treated group. Serial sections ofbrainstems of all groups were cut and NADPH-d staining, which selectively stains the nitric acid synthase-containing neurons, was done.

RESULTS

Histopathological changes due to chronic reflux esophagitis was observed in the reflux group. The ranitidine treatment and sham control groups showed no changes related to esophagitis. The staining in the dorsal motor nucleus of the vagus and nucleus tractus solitarius showed statistically significant differences compared to the control group (P < 0.0001).

CONCLUSION

The increased nitric oxide expressions in the dorsal vagal nucleus and nucleus tractus solitarius are most probably due to adaptive changes to disturbed esophageal motility and mucosal damage.

Immunomodulatory effect of cimetidine in common carp (Cyprinus carpio L.)

The main indication of cimetidine is being H₂-receptor antagonist, but studies suggest that cimetidine may also act as a non-specific stimulant of cell-mediated immunity and immunomodulator. In order to determine the immunomodulatory effect of dietary intake of cimetidine in the common carp (100 ± 10 g), subjects were fed diets containing 0 (control), 50, 100 and 200 mg cimetidine kg⁻¹ of dry diet for a period of 6 weeks. TLC and NBT assays were significantly (P < 0.05) stimulated in cimetidine-supplemented groups displaying the highest value in 200 mg kg⁻¹ group. A decrease (P < 0.05) in cortisol and ACH50 value was recorded in fish treated with cimetidine. Serum protein, albumin and serum globulin levels were not significantly changed. The findings of the present investigation suggest that the incorporation of cimetidine in the diet of common carp enhances the non-specific immunity.

NF-kB overexpression and decreased immunoexpression of AR in the muscular layer is related to structural damages and apoptosis in cimetidine-treated rat vas deferens

BACKGROUND

Cimetidine, histamine H2 receptors antagonist, has caused adverse effects on the male hormones and reproductive tract due to its antiandrogenic effect. In the testes, peritubular myoid cells and muscle vascular cells death has been associated to seminiferous tubules and testicular microvascularization damages, respectively. Either androgen or histamine H2 receptors have been detected in the mucosa and smooth muscular layer of vas deferens. Thus, the effect of cimetidine on this androgen and histamine-dependent muscular duct was morphologically evaluated.

METHODS

The animals from cimetidine group (CMTG; n=5) received intraperitoneal injections of 100 mg/kg b.w. of cimetidine for 50 days; the control group (CG) received saline solution. The distal portions of vas deferens were fixed in formaldehyde and embedded in paraffin. Masson´s trichrome-stained sections were subjected to morphological and the following morphometrical analyzes: epithelial perimeter and area of the smooth muscular layer. TUNEL (Terminal deoxynucleotidyl-transferase mediated dUTP Nick End Labeling) method, NF-kB (nuclear factor kappa B) and AR (androgen receptors) immunohistochemical detection were also carried out. The birefringent collagen of the muscular layer was quantified in picrosirius red-stained sections under polarized light. The muscular layer was also evaluated under Transmission Electron Microscopy (TEM).

RESULTS

In CMTG, the mucosa of vas deferens was intensely folded; the epithelial cells showed numerous pyknotic nuclei and the epithelial perimeter and the area of the muscular layer decreased significantly. Numerous TUNEL-labeled nuclei were found either in the epithelial cells, mainly basal cells, or in the smooth muscle cells which also showed typical features of apoptosis under TEM. While an enhanced NF-kB immunoexpression was found in the cytoplasm of muscle cells, a weak AR immunolabeling was detected in these cells. In CMTG, no significant difference was observed in the birefringent collagen content of the muscular layer in comparison to CG.

CONCLUSIONS

Cimetidine induces significant damages in the epithelium; a possible antiandrogenic effect on the basal cells turnover should be considered. The cimetidine-induced muscle cells apoptosis confirms the susceptibility of these cells to this drug. The parallelism between enhanced cytoplasmic NF-kB immunolabeling in the damaged muscular tissue and muscle cell apoptosis suggests that this drug may avoid the translocation of NF-kB to the nucleus and interfere in the control of NF-kB-mediated smooth muscle cell apoptosis. The decreased immunoexpression of ARs verified in the damaged muscular tissue reinforces this possibility.

Effect of Food, an Antacid, and the H2Antagonist Ranitidine on the Absorption of BAY 59-7939 (Rivaroxaban), an Oral, Direct Factor Xa Inhibitor, in Healthy Subjects

To investigate the influence of food and administration of an antacid (aluminum-magnesium hydroxide) or ranitidine on the absorption of BAY 59-7939 (rivaroxaban), 4 randomized studies were performed in healthy male subjects. In 2 food interaction studies, subjects received BAY 59-7939, either as two 5-mg tablets (fasted and fed), four 5-mg tablets (fasted), or one 20-mg tablet (fasted and fed). In 2 drug interaction studies, BAY 59-7939 (six 5-mg tablets) was given alone or with ranitidine (150 mg twice daily, preceded by a 3-day pretreatment phase) or antacid (10 mL). Plasma samples were obtained to assess pharmacokinetic and pharmacodynamic parameters of BAY 59-7939. In the presence of food, time to maximum concentration (t(max)) was delayed by 1.25 hours; maximum concentration (C(max)) and area under the curve (AUC) were increased, with reduced interindividual variability at higher doses of BAY 59-7939. Compared with baseline, BAY 59-7939 resulted in a relative increase in maximum prothrombin time (PT) prolongation of 44% (10 mg) and 53% (20 mg) in the fasted state, compared with 53% and 83% after food. Time to maximum PT prolongation was delayed by 0.5 to 1.5 hours after food, with no relevant influence of food type. No significant difference in C(max) and AUC was observed with coadministration of BAY 59-7939 and ranitidine or antacid.

Impact of Chronic Oral H2-Antagonist Therapy on Left Ventricular Systolic Function and Exercise Capacity

It has been suggested that H2-antagonists may adversely affect left ventricular systolic function. To assess the effects of cimetidine, famotidine, and ranitidine on exercise capacity and left ventricular systolic function, the authors conducted a randomized, double-blind, four-way crossover study in 15 healthy male volunteers with placebo control. Each subject underwent a maximal upright treadmill exercise test, aerobic metabolic assessment, and two-dimensional stress echocardiography on six separate occasions. The initial two treadmill exercise tests with aerobic metabolic assessment and stress echocardiography were performed to minimize the learning effect. In the final four evaluations, subjects were randomized to receive 7 days of oral treatment with cimetidine 400 mg twice daily, famotidine 40 mg daily, ranitidine 150 mg twice daily, and placebo. A comparison of exercise tests, aerobic metabolic assessment, and stress echocardiography results found no significant differences between any of the H2-antagonists and placebo. In addition, there were no significant differences in test results between cimetidine, famotidine, and ranitidine. Specifically, exercise treadmill time, maximal oxygen consumption, respiratory quotient, maximal exercise systolic and diastolic blood pressure, maximal exercise heart rate, left ventricular end-diastolic dimension, left ventricular end-systolic dimension, and ejection fraction were not different between treatments. The authors conclude that 7 days of oral treatment with cimetidine, famotidine, or ranitidine has no deleterious effect on exercise capacity or left ventricular systolic function in healthy subjects.

Famotidine suppresses osteogenic differentiation of tendon cells in vitro and pathological calcification of tendon in vivo

Heterotopic ossification or calcification follows any type of musculoskeletal trauma and is known to occur after arthroplasties of hip, knee, shoulder, or elbow; fractures; joint dislocations; or tendon ruptures. Histamine receptor H2 (Hrh2) has been shown to be effective for reducing pain and decreasing calcification in patients with calcifying tendinitis, which suggested that H2 blockers were effective for the treatment of tendon ossification or calcification. However, the detailed mechanisms of its action on tendon remain to be clarified. We investigated the mechanisms underlying H2 blocker-mediated suppression of tendon calcification, with a focus on the direct action of the drug on tendon cells. Famotidine treatment suppressed the mRNA expressions of Col10a1 and osteocalcin, ossification markers, in a tendon-derived cell line TT-D6, as well as a preosteoblastic one MC3T3-E1. Both of the cell lines expressed Hrh2; histamine treatment induced osteocalcin expression in these cells. Famotidine administration suppressed calcification in the Achilles tendon of ttw mice, a mouse model of ectopic ossification. These data suggest that famotidine inhibits osteogenic differentiation of tendon cells in vitro, and this inhibition may underlie the anti-calcification effects of the drug in vivo. This study points to the use of H2 blockers as a promising strategy for treating heterotopic ossification or calcification in tendon, and provides evidence in support of the clinical use of famotidine.

Effect of short-term proton pump inhibitor treatment and its discontinuation on chromogranin A in healthy subjects

CONTEXT

Chromogranin A (CgA) is used as a generic tumor marker for neuroendocrine tumors. Proton pump inhibitors (PPI) are known to increase CgA, but it is not clear to what extent, and there is little information on how long PPI need to be discontinued before the effect of PPI has disappeared. Furthermore, is it not known whether this PPI effect is dependent on the CgA assay used.

OBJECTIVE

The aim of the study was to determine the effect of 7-d treatment with a PPI and its discontinuation on CgA in serum and plasma comparing four CgA assays.

DESIGN AND PARTICIPANTS

Seventeen healthy subjects took lansoprazole 30 mg at bedtime for 7 d, and blood samples for CgA were obtained at baseline, d 7 of PPI use, and 1, 2, 4, and 7 d after discontinuation of the PPI. In all samples, CgA was measured using the following assays: Alpco (serum and plasma), Cis-Bio (serum and plasma), DAKO, and Cis-Bio radioisotope assay.

RESULTS

When using the same assay, CgA was higher in plasma than in serum. Treatment with a PPI for 1 wk resulted in a significant (about 2.5-fold) increase in CgA with significant interindividual variation. After discontinuation of PPI, serum CgA gradually declined, with a half-life of 4-5 d.

CONCLUSION

Short-term PPI use results in a significant increase of CgA in serum and plasma, an effect that is largely independent of the assay used. PPI need to be discontinued for 2 wk to fully eliminate their effect on CgA. This effect of PPI needs to be considered when interpreting results of CgA measurements.

Histamine is a modulator of metamorphic competence in Strongylocentrotus purpuratus (Echinodermata: Echinoidea)

BACKGROUND

A metamorphic life-history is present in the majority of animal phyla. This developmental mode is particularly prominent among marine invertebrates with a bentho-planktonic life cycle, where a pelagic larval form transforms into a benthic adult. Metamorphic competence (the stage at which a larva is capable to undergo the metamorphic transformation and settlement) is an important adaptation both ecologically and physiologically. The competence period maintains the larval state until suitable settlement sites are encountered, at which point the larvae settle in response to settlement cues. The mechanistic basis for metamorphosis (the morphogenetic transition from a larva to a juvenile including settlement), i.e. the molecular and cellular processes underlying metamorphosis in marine invertebrate species, is poorly understood. Histamine (HA), a neurotransmitter used for various physiological and developmental functions among animals, has a critical role in sea urchin fertilization and in the induction of metamorphosis. Here we test the premise that HA functions as a developmental modulator of metamorphic competence in the sea urchin Strongylocentrotus purpuratus.

RESULTS

Our results provide strong evidence that HA leads to the acquisition of metamorphic competence in S. purpuratus larvae. Pharmacological analysis of several HA receptor antagonists and an inhibitor of HA synthesis indicates a function of HA in metamorphic competence as well as programmed cell death (PCD) during arm retraction. Furthermore we identified an extensive network of histaminergic neurons in pre-metamorphic and metamorphically competent larvae. Analysis of this network throughout larval development indicates that the maturation of specific neuronal clusters correlates with the acquisition of metamorphic competence. Moreover, histamine receptor antagonist treatment leads to the induction of caspase mediated apoptosis in competent larvae.

CONCLUSIONS

We conclude that HA is a modulator of metamorphic competence in S. purpuratus development and hypothesize that HA may have played an important role in the evolution of settlement strategies in echinoids. Our findings provide novel insights into the evolution of HA signalling and its function in one of the most important and widespread life history transitions in the animal kingdom--metamorphosis.

Effect of restraint stress on nociceptive responses in rats: role of the histaminergic system

Stress induced analgesia (SIA) is well known, but the reverse phenomenon, hyperalgesia is poorly documented. This study investigated the role of the histaminergic system in restraint stress hyperalgesia in rats, using thermal stimulation method (hot plate and tail flick tests). Paw licking and tail withdrawal latencies were taken before and after restraint for about one hour. Significant decreases (p<0.05) were obtained in these latencies after the restraint in both tests. Administration of H1 and H2 receptor blockers, chlorpheniramine and cimetidine respectively 30 mins before the restraint still resulted in significant reductions (p<0.05) in these latencies, connoting the persistence of hyperalgesia, showing that histamine H1 and H2 receptors did not participate in the mechanism of restraint stress hyperalgesia. We therefore suggest a histaminergic independent mechanism for restraint stress induced hyperalgesia.

Histamine promotes rat motor performances by activation of H(2) receptors in the cerebellar fastigial nucleus

The cerebellar fastigial nucleus (FN), together with the interpositus nucleus (IN), constitutes the two final output nuclei of the spinocerebellum and plays an important role in body and limb movements. Previous studies have revealed a direct histaminergic projection from the hypothalamus to the cerebellar nuclei and an excitatory effect of histamine on the IN neurons. However, role of hypothalamic histaminergic projection in the FN has been still little known. Here we show that histamine elicited the FN neurons of rats a concentration-dependent excitatory response in vitro. The histamine-induced excitation on FN neurons was mediated by postsynaptic histamine H2 rather than H1 receptors. In behavioral tests, microinjection of histamine into bilateral FNs remarkably improved motor performances of rats on both accelerating rota-rod and balance beam. Selective H2 receptor antagonist ranitidine considerably declined those motor performances and selective H2 receptor agonist dimaprit mimicked the facilitation effect of histamine on the movements. But selective H1 receptor antagonist triprolidine and agonist 2-pyridylethylamine had no effect. Furthermore, microinjection of histamine into bilateral FNs narrowed stride width of footprint but did not influence wire suspension, whereas microinjection of histamine into bilateral INs increased stride length and promoted suspension. These results demonstrate that histamine enhances rat motor balance and coordination through modulation of both proximal and distal muscles by activation of histamine H2 receptors in the cerebellar FN and IN, and suggest that the hypothalamocerebellar histaminergic projections may modulate the final outputs of the spinocerebellum and participate in the cerebellum-mediated motor control.

Mast cell-derived TNF-α and histamine modify IL-6 and IL-8 expression and release from cutaneous tumor cells

The coincidence of skin tumors and elevated mast cell (MC) numbers has been known for many years. However, it has remained controversial whether, in this context, MCs promote or inhibit tumor growth. Addressing this problem, different melanoma and squamous cell carcinoma cell lines were co-cultivated with primary, dermal MC for 24 h and gene or protein expression of cytokines tumor necrosis factor (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL-8) estimated. Co-culture with MCs led to an increase in IL-8 gene expression and IL-8 protein release from melanoma cells and IL-6 and IL-8 gene expression and protein release from squamous cell carcinoma cells, respectively. Moreover induction of IL-6 and IL-8 was primarily regulated by MC-derived TNF-α. Our data suggest an interplay between MCs and tumor cells, which results in altered cytokine release and may, thus, have an impact on tumor growth, invasion and neovascularisation.

Cimetidine enhances antigen-specific IgE and Th2 cytokine production

BACKGROUND

Treatment with anti-ulcer drugs has been shown to enhance IgE production against food antigens. However, little is known about the immunological effects of cimetidine, a histamine receptor type 2 (H2R) antagonist that is widely used as an anti-ulcer drug, in allergy. Therefore, the present study investigated the role of cimetidine in Th2 immune responses in mice.

METHODS

BALB/c mice were immunized intraperitoneally with ovalbumin (OVA) with and without cimetidine. The levels of cytokines in supernatants of spleen cells cultured in the presence of OVA for 4 days and the levels of total and OVA-specific IgG(1), IgG(2a) and/or IgE in sera from these mice were determined by ELISA.

RESULTS

Administration of cimetidine to OVA-sensitized BALB/c mice promoted Th2 cytokine secretion by OVA-stimulated spleen cells in vitro and increased serum levels of OVA-specific IgE, IgG(1) and IgG(2a).

CONCLUSIONS

These results indicate that cimetidine can enhance Th2 responses, suggesting that cimetidine may contribute to IgE production in allergies.

Differential risk of Clostridium difficile infection with proton pump inhibitor use by level of antibiotic exposure

PURPOSE

Clostridium difficile infection (CDI) is a major cause of hospital-acquired diarrhea worldwide. We examined the risk of CDI associated with the use of acid-suppressive agents (proton pump inhibitors [PPI] and histamine-2 receptor blockers) and determined whether this risk varied by number or type of antibiotic (high or low CDI risk) received during hospitalization.

METHODS

We conducted a retrospective cohort study of hospitalizations among adult patients at an academic teaching hospital in Rochester, New York, during which two or more days of antibiotics were prescribed. Multivariable marginal Cox proportional hazards models with time-varying exposures were used to examine time to the development of CDI.

RESULTS

A total of 10 154 hospitalizations and 241 cases of CDI, defined as detection of C. difficile toxin in a diarrheal stool sample within 60 days of discharge, were identified. PPI use was independently associated with an increased risk of CDI (adjusted hazard ratio = 4.5; 95% confidence interval [CI] = 2.3-9.0). Among hospitalizations during which one, two, three or four, and five or more antibiotics were prescribed, the adjusted hazard ratios for PPI use were 15.7 (CI = 6.4-38.8), 4.9 (CI = 2.2-11.2), 4.3 (CI = 1.9-9.9), and 2.7 (CI = 1.2-5.9), respectively (p for interaction = .002).

CONCLUSIONS

The use of PPI is common among patients receiving antibiotics during hospitalization. The greater risk of CDI in relation to PPI among hospitalizations during which fewer or low-risk antibiotics were prescribed suggests a potentially clinically relevant interaction between antibiotics and PPI. Further study is needed to elucidate possible mechanisms for the observed effect.

A case-control study of community-associated Clostridium difficile infection: no role for proton pump inhibitors

BACKGROUND

The epidemiology of community-associated Clostridium difficile infection is not well known. We performed a multicenter, case-control study to further describe community-associated C. difficile infection and assess novel risk factors.

METHODS

We conducted this study at 5 sites from October 2006 through November 2007. Community-associated C. difficile infection included individuals with diarrhea, a positive C. difficile toxin, and no recent (12 weeks) discharge from a health care facility. We selected controls from the same clinics attended by cases. We collected clinical and exposure data at the time of illness and cultured residual stool samples and performed ribotyping.

RESULTS

Of 1041 adult C. difficile infections, 162 (15.5%) met criteria for community-associated: 66 case and 114 control patients were enrolled. Case patients were relatively young (median 64 years), female (56%), and frequently required hospitalization (38%). Antimicrobials, malignancy, exposure to high-risk persons, and remote health care exposure were independently associated with community-associated C. difficile infection. In 40% of cases, we could not confirm recent antibiotic exposure. Stomach-acid suppressants were not associated with community-associated infection, and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors appeared protective. Prevalence of the hypervirulent NAP-1/027 strain was infrequent (17%).

CONCLUSIONS

Community-associated C. difficile infection resulted in a substantial health care burden. Antimicrobials are a significant risk factor for community-associated infection. However, other unique factors also may contribute, including person-to-person transmission, remote health care exposures, and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors. A role for stomach-acid suppressants in community-associated C. difficile infection is not supported.

Symptomatic dermatographism: current concepts in clinical practice with an emphasis on the pediatric population

Symptomatic dermatographism reflects an exaggerated cutaneous response to the physical stimulus of pressure. Some consider it a common type of childhood physical urticaria. Its etiology can vary widely from drug reactions and infectious agents to systemic diseases and genetic inheritance. The mechanism is thought to be related to histamine degranulation due to a mechano-immunologic trigger, leading to the common symptoms of pruritus and burning in areas exposed to increased pressure, such as tight clothing, belts, and waistbands. The diagnosis typically is made with a blunt object such as a tongue blade or unopened ball-point pen pressed along the back and/or forearm, which elicits urtication. The mainstay of treatment is H1- and H2-receptor antagonists but also can include immunosuppressive agents, steroids, and phototherapy for refractory or severe cases.

Novel approaches to inhibition of gastric acid secretion

The gastric H,K-adenosine triphosphatase (ATPase) is the primary target for treatment of acid-related diseases. Proton pump inhibitors (PPIs) are weak bases composed of two moieties, a substituted pyridine with a primary pK(a) of about 4.0 that allows selective accumulation in the secretory canaliculus of the parietal cell, and a benzimidazole with a second pK(a) of about 1.0. Protonation of this benzimidazole activates these prodrugs, converting them to sulfenic acids and/or sulfenamides that react covalently with one or more cysteines accessible from the luminal surface of the ATPase. The maximal pharmacodynamic effect of PPIs as a group relies on cyclic adenosine monophosphate-driven H,K-ATPase translocation from the cytoplasm to the canalicular membrane of the parietal cell. At present, this effect can only be achieved with protein meal stimulation. Because of covalent binding, inhibitory effects last much longer than their plasma half-life. However, the short dwell-time of the drug in the blood and the requirement for acid activation impair their efficacy in acid suppression, particularly at night. All PPIs give excellent healing of peptic ulcer and produce good, but less than satisfactory, results in reflux esophagitis. PPIs combined with antibiotics eradicate Helicobacter pylori, but success has fallen to less than 80%. Longer dwell-time PPIs promise to improve acid suppression and hence clinical outcome. Potassium-competitive acid blockers (P-CABs) are another class of ATPase inhibitors, and at least one is in development. The P-CAB under development has a long duration of action even though its binding is not covalent. PPIs with a longer dwell time or P-CABs with long duration promise to address unmet clinical needs arising from an inability to inhibit nighttime acid secretion, with continued symptoms, delayed healing, and growth suppression of H. pylori reducing susceptibility to clarithromycin and amoxicillin. Thus, novel and more effective suppression of acid secretion would benefit those who suffer from acid-related morbidity, continuing esophageal damage and pain, nonsteroidal anti-inflammatory drug-induced ulcers, and nonresponders to H. pylori eradication.

Time-dependent changes of immunologic responses after burn injury and immunomodulation by cimetidine and pyrimethamine in an animal model

Severe suppression of the immune system is the major cause of infections following burn injury. The aim of this study was to investigate the time-related alterations of immune responses following thermal injury in an animal model and also to modulate immune responses by use of the immunomdulators cimetidine and pyrimethamine. Male Balb/c mice were anesthetized and given a 10% total body surface area full-thickness burn. The time-dependent changes of delayed type hypersensitivity (DTH) and antibody responses to sheep red blood cell (SRBC) were assessed at post-burn days (PBD). The effects of different doses of cimetidine and pyrimethamine on DTH response were also quantitated at 10 PBD. Marked suppression of DTH response occurred during 30 days after burn trauma, with maximal suppression occurring between 10 to 14 days after burn injury. Simultaneously the antibody response to SRBC was significantly increased after thermal trauma. Cimetidine (at doses of 10 and 15 mg/kg) and pyrimethamine (at doses of 5 and 10 mg/kg) significantly augmented DTH response after thermal injury. These results showed that the severe time-dependent alterations occurred in DTH and antibody responses following burn injury. Cimetidine and pyrimethamine also restore burn-induced suppression of DTH response following thermal trauma.

Chromogranin A (CgA)--the influence of various factors in vivo and in vitro, and existing disorders on it's concentration in blood

Chromogranin A (CgA) is regarded as a major, nonspecific neuroendocrine tumour (NET) marker. The results of CgA blood concentration, however, may actually be influenced by various factors or coexisting pathological conditions. Among the factors causing a substantial increase of the blood CgA concentration are: treatment with proton-pump inhibitors or H₂-receptor blockers, chronic atrophic gastritis (type A), impaired renal function, prostate cancer and BPH, and rheumatoid arthritis with high level of RF IgM. In addition, the sort of investigated biological material (whether it is serum or plasma) is of importance. There are also many conditions which may have a moderate or little influence on the concentration of CgA, among them are: inflammatory bowel disease (ulcerative colitis and Crohn's disease), deteriorating liver function, untreated essential hypertension, heart failure, hypercortisolism, pregnancy, and, in some subjects, ingestion of a meal. Proper assessment of the CgA results requires detailed knowledge about various factors, drugs, and pathological conditions influencing its concentration in blood.

Repeated histamine pretreatment decreased amnesia induced by post-training administration of the drug in a step-down inhibitory avoidance test in mice

BACKGROUND

Repeated administration of certain drugs could result in an enhancement of the behavioral effects of those drugs. In the present study, the effect of repeated administration of histamine on amnesia induced by post-training administration of the drug was examined.

METHODS

A single trial step-down inhibitory (passive) avoidance task was used for memory assessment in male NMRI mice.

RESULTS

The results showed that post-training administration of different doses of histamine (5, 10, and 20 microg/mouse, i.c.v.) decreased the step-down latency on the test day. Repeated pretreatment of histamine (10 and 20 microg/mouse) for three days followed by five days of no drug treatment prevented amnesia due to post-training histamine (20 microg/mouse). In contrast, repeated administration of histamine H1 receptor antagonist, pyrilamine (5, 10, and 20 mg/kg) or histamine H2 receptor antagonist, ranitidine (12.5 and 25 mg/kg) 10 minutes prior to histamine injections, decreased the effect of repeated histamine administration. Moreover, a similar pattern was seen in animals which received dopamine D1 receptor antagonist, SCH 23390 (0.025, 0.5, and 1 mg/kg) or dopamine D2 receptor antagonist, sulpiride (0.2, 1, and 5 mg/kg) 10 minutes prior to histamine injections during the repeated pretreatment.

CONCLUSION

The results indicated that both the histamine and dopamine receptor mechanisms may be involved in the effects of repeated pretreatment of histamine on drug induced amnesia.

Gastroprotective effect of earthworm paste (Lampito mauritii, Kinberg) on experimental gastric ulcer in rats

BACKGROUND

For thousands of years, earthworm and its products have been used for its therapeutic benefits. The traditional medical knowledge of indigenous people throughout the world more particularly in Asia, including India, Myanmar, China, Korea and Vietnam has played vital role in identifying, extracting and using biologically active compounds from earthworms.

MATERIALS AND METHODS

Effect of various doses (20, 40, 80, 160 and 320 mg/kg, po) of earthworm paste (Lampito mauritii, Kinberg) was studied on aspirin-induced gastric ulcer and compared to ranitidine.

RESULTS

The earthworm paste showed significant ulcer protective effects.The cytoprotective effect of the earthworm paste seems to be not only due to the anti-secretory action but also to the effects on mucosal glycoprotein. The decrease in total acidity, pepsin and protein content of the gastric juice proved the antiulceral activity of earthworm paste. Histopathological studies revealed that the earthworm paste was more effective in gastric cytoprotection than ranitidine in preventing lesion formation.

CONCLUSIONS

These observations show that the earthworm paste possess antiulcer potential.

Effects of the histamine H2 receptor antagonist famotidine on the healing of colonic anastomosis in rats

BACKGROUND

Failure of anastomotic healing is one of the major complications in colorectal surgery. Because histamine plays an important role in immune and inflammatory reactions, we demonstrate the effects of famotidine on the healing of colonic anastomosis in rats.

METHODS

Twenty-eight Sprague-Dawley rats were used in the study. Excision and end-to-end anastomosis was performed in the distal colon of the rat. The Famotidine Group received 2 mg/kg/day famotidine; the Control Group received the same amount of saline. Bursting pressure of anastomoses and hydroxyproline content of perianastomotic tissues were evaluated on the third and seventh days following surgery.

RESULTS

Bursting pressures and hydroxyproline contents for the Famotidine Group were significantly lower than the equivalent parameters for the Control Group on both the third and seventh days post-surgery.

CONCLUSIONS

According to our findings, famotidine exerts detrimental effects on the anastomotic bursting pressure and hydroxyproline content of perianastomotic tissues in the colon of rats.

Effect of cimetidine on the electrophysiologic profile of isolated visceral sheep peritoneum

The peritoneal mesothelium is a barrier to ion transport in peritoneal dialysis. Cimetidine is an H2 receptor antagonist and a potent inhibitor of Na+/H+ antiporter, which is found in the plasma membranes of various cell types, including mesothelial cells. Recent reports linked Na+/H+ antiporter stimulation with increasing peritoneal fibroblast proliferation. The aim of the present study was to investigate by means of Ussing chamber experiments the effect of cimetidine on the transmesothelial electrical resistance (R) of isolated visceral sheep peritoneum. Peritoneal samples obtained from adult sheep were collected from the slaughterhouse and transferred in oxygenated Krebs-Ringer bicarbonate (KRB) solution to the laboratory within 30 minutes of the animal's death. The peritoneal tissue was transferred in a cooled KRB solution (4 degrees C, pH 7.5) bubbled with 95% O2/5% CO2. A planar sheet of the visceral peritoneum was mounted in an Ussing-type chamber and cimetidine (10(-3) mol/L) was added to the solution on the apical and basolateral sides. The R was measured before and for 15 minutes serially after addition of the cimetidine. Results presented are the means +/- standard error of the mean of 12 experiments. Addition of cimetidine basolaterally induced, within 1 minute, an increase in the deltaR of 35.97% +/- 12.01% (p < 0.05), which returned to baseline after 15 minutes. The action of cimetidine on the apical side of the membrane was similar, with a rapid rise in the deltaR of 47.3% +/- 16.4% (p < 0.05) and a subsequent decline to control values. The R is inversely correlated with membrane permeability. The results of the present study indicate a rapid action of cimetidine on the permeability of visceral sheep peritoneum, probably through inhibition of mesothelial Na+/H+ antiporter. The increase in R observed after addition of the cimetidine clearly indicates the existence of Na+/H+ antiporter on both sides of visceral sheep peritoneum. The clinical implications of our results should be further investigated.

[Effects of H2-blockers on alcohol dehydrogenase (ADH) activity]

First-pass metabolism (FPM) of alcohol is demonstrated by lower blood alcohol concentrations after oral than intravenous administration of the same dose. FPM occurs predominantly in the stomach and has been attributed to class IV of alcohol dehydrogenase (ADH) isoenzyme localizated in the gastric mucosa. A number of factors that influence on gastric ADH activity and thereby modulate FPM have been identified. These include age, sex, ethnicity, concentrations and amounts of alcohol consumed and drugs. Several H2-receptor antagonists, including cimetidine and ranitidine, inhibit gastric ADH activity and reduce FPM, resulting in higher blood alcohol concentrations after H2-blockers administration.

In vitro and in vivo evaluation of ranitidine hydrochloride loaded hollow microspheres in rabbits

The objective of this investigation was to develop the hollow microspheres as a new dosage form of floating drug delivery systems with prolonged stomach retention time. Hollow microspheres containing ranitidine hydrochloride (RH) were prepared by a novel solvent diffusion-evaporation method using ethyl cellulose (EC) dissolved in a mixture of ethanol and ether (6:1.0, v/v). The yield and drug loading amount of hollow microspheres were 83.21+/-0.28% and 20.71+/-0.32%, respectively. The in vitro release profiles showed that the drug release rate decreased with increasing viscosity of EC and the diameter of hollow microspheres, while increased with the increase of RH/EC weight ratio. Hollow microspheres could prolong drug release time (approximately 24 h) and float over the simulate gastric fluid for more than 24 h. Pharmacokinetic analysis showed that the bioavailability from RH-hollow microspheres alone was about 3.0-times that of common RH gelatin capsules, and it was about 2.8-times that of the solid microspheres. These results demonstrated that RH hollow microspheres were capable of sustained delivery of the drug for longer period with increased bioavailability.

Effects of chlorpheniramine and ranitidine on the visceral nociception induced by acetic acid in rats: role of opioid system

In this study, effects of chlorpheniramine (H1-receptor blocker), ranitidine (H2-receptor blocker), morphine (an opioid agonist) and naloxone (an opioid antagonist) in separate and combined treatments were investigated on the visceral nociception in rats. Visceral nociception was induced by intraperitoneal injection of acetic acid (1 mL, 1%). The latency time to the beginning of the first abdominal wall contraction (first writhe) was measured and the numbers of writhes were counted for 1 h after acetic acid injection. Intraperitoneal injections of chlorpheniramine and ranitidine significantly (p < 0.05) increased the latency time to the beginning of the first writhe and also significantly (p < 0.05) decreased the numbers of writhes. The same results were obtained after subcutaneous injection of morphine. Subcutaneous injection of naloxone did not change the intensity of visceral nociception, but significantly (p < 0.05) prevented the morphine-induced antinociception. Intraperitoneal injection of chlorpheniramine significantly (p < 0.05) enhanced the morphine-induced analgesia, but did not reverse the effect of naloxone on nociceptive responses. Intraperitoneal injection of ranitidine, with no effect on the morphine-induced antinociception, significantly (p < 0.05) reversed the effect of naloxone on pain responses. These results suggest that both chlorpheniramine and ranitidine exert antinociceptive effect in the visceral nociception. In addition, morphine through a naloxone-dependent mechanism produces visceral antinociception. Moreover, the endogenous opioid system may participate in the chlorpheniramine- but not in the ranitidine-induced antinociception.

Comparison of the kinetic characteristics of inhibitory effects exerted by biguanides and H2-blockers on human and rat organic cation transporter-mediated transport: Insight into the development of drug candidates

In this study, the comparison of the transport of substrates (1-methyl-4-phenylpydinium (MPP) and tetraethyl ammonium (TEA)) and the inhibition potency of the inhibitors (biguanides and H(2)-blockers) for human and rat organic cation transporters (hOCTs and rOcts), and the inhibition type of inhibitors for these transporters were investigated using HEK293 cells that stably express hOCT/rOct. The concentration-dependent uptake of [(3)H]-MPP and [(14)C]-TEA by hOCT1-3/rOct1-3 had K(m) values similar to those in the literature. It was also deduced that MPP and TEA are competitive inhibitors for hOCT1-2/rOct1-2. The K(i) values for phenformin inhibition of [(3)H]-MPP and [(14)C]-TEA uptake by hOCT1-3/rOct1-3 were lower than that for metformin. The [(3)H]-MPP uptake by hOCT1/rOct1 and hOCT3/rOct3 was inhibited by famotidine and ranitidine whereas that by hOCT2/rOct2 was not. The inhibitory potency of cimetidine for hOCT1-2 was very weak. In most cases, the differences in the V(max)/K(m) values of substrates and the K(i) values of inhibitors between hOCT and rOct were minor. The acquisition of information on OCT/Oct mediated-transport and/or inhibition such as that presented in this report is very useful for further understanding of certain aspects of uptake, distribution, and excretion for drug candidates.

The use of phosphodiesterase 5 inhibitors with concomitant medications

The phosphodiesterase-5 inhibitors (PDE5i) sildenafil, vardenafil, and tadalafil are considered first-line therapy for the treatment of patients with erectile dysfunction (ED). In addition to the classical pro-erectile-effect, clinical findings have suggested that they can also influence vascular tone in pulmonary, coronary and other vascular tissues, as well as improving symptoms associated with benign prostatic hyperplasia. Therefore, considering the hypothetical widespread application of PDE5i, the potential for drug-drug interactions emerges as a relevant factor in determining the safety profile of PDE5i. Review of relevant literature was conducted using data sources from MEDLINE (1998, to June 2007). The use of nitrates remains the only contraindication for all 3 PDE5i. Vardenafil is also not recommended in patients taking type 1A (such as quinidine, or procainamide) or type 3 antiarrhythmics (such as sotalol, or amiodarone) while no other major limitations have been reported for tadalafil and sildenafil. In contrast to previously reported labeling, recent studies have suggested only a precaution, but not contraindication with the concomitant use of alpha-blockers agents. In addition, precaution is also suggested in the presence of potent CYP3A inhibitors, such as azole antifungals, antiretroviral protease inhibitors, or macrolid antibiotics. This is because sildenafil, vardenafil, and tadalafil are metabolized mainly via the CYP3A4 pathway. On the other hand, statins and testosterone seem to have synergic effects with PDE5i on sexual activity.