Safety, pharmacokinetics and pharmacodynamics of a novel anti-asthmatic drug, XC8, in healthy probands.

INTRODUCTION: XC8 (histamine glutarimide) is a novel agent which targets eosinophilic migration and mast cell degranulation and has shown anti-asthmatic effects in animal studies. OBJECTIVE: The objective of this placebo-controlled phase 1 study was to assess the safety of oral XC8 and to evaluate its pharmacokinetic and pharmacodynamic properties. METHODS: 32 healthy volunteers in three dose-escalation treatment groups (10 mg [n = 8], 50 mg [n = 8] and 200 mg [n = 16]) were randomized in a 3:1 ratio to XC8 or placebo respectively. The subjects received a single dose of the drug at Day 1 and then once-daily for 14 days (Days 8-21). RESULTS: No severe adverse events occurred. The number of adverse events was similar in the treatment arms compared to placebo and all subjects completed the study as planned. No clinically significant changes occurred in hematologic and biochemical blood tests in subjects receiving XC8. The pharmacokinetic data showed similar dose and time dependent mean plasma XC8 concentrations after single (Day 1) and multiple (Day 21) dosing. The mean maximum concentrations were 114-1993 ng/mL after single and 115-2089 ng/mL after multiple dosing. The mean times to maximum concentration were 0.68-1.01 and 0.67-0.98 h, respectively. There was no evidence for accumulation of XC8 after multiple dosing. CONCLUSION: XC8 was safe and well tolerated. A phase 2 study is being performed to further evaluate the potential role of XC8 in asthma treatment. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02882217.

[Investigations into the distribution of neohistamine methylsulfate in the organism of the warm blooded animals following its intragastric administration]. / Izuchenie raspredeleniia neostigmina metilsul'fata v organizme teplokrovnykh zhivotnykh posle vnutrizheludochnogo vvedeniia.

The objective - of the present study was to elucidate the specific features of the distribution of neohistamine methylsulfate (proserin) in the organism of the omnivorous warm blooded animals following its intragastric administration. The analytical methods included TLC, HPLC, and UV-spectrophotometry. Neohistamine methylsulfate was administered intrgastrically to the male Wistar rats at a dose equivalent to the triple LD50 dose. The substance of interest was extracted by acetone from the biological matrices of the dead animals and purified by sequential treatment with the relevant solvents and chromatography in a thin layer of the reverse-phase sorbent (C14-C15 bonded phase model) with the elution in the buffer solution (pH 1.98) - acetone (8:2) system. The compound of interest was identified based on the Rf values (obtained by TLC), retention time (in HPLC), and the spectral characteristics. The quantitative determination of the analyte in the biomatrices was performed with the use of UV spectrophotometry. The analytical methods were validated based on the criteria for linearity, selectivity, correctness, and precision as well as detection threshold and results of quantitation. The largest amount of the study compound were determined in the heart (365.2±33.94 mcg/g), spleen (288.6±24.97 mcg/g), kidney (127.6±9.33 mcg/g), and the gastric walls (124.6±12.17 mcg/g) of the experimental animals.

Population pharmacokinetic/pharmacodynamic modeling of histamine response measured by histamine iontophoresis laser Doppler.

The epicutaneous histamine (EH) test is the current gold standard method for the clinical evaluation of allergic conditions. However, the EH method is limited in providing an objective and qualitative assessment of histamine pharmacodynamic response. The histamine iontophoresis with laser Doppler (HILD) monitoring method, an alternative method, allows a fixed dose of histamine to be delivered and provides an objective, continuous, and dynamic measurement of histamine epicutaneous response in children and adults. However, due to the high sampling frequency (up to 40 Hz), the output files are usually too cumbersome to be directly used for further analysis. In this study, we developed an averaging algorithm that efficiently reduces the HILD data in size. The reduced data was further analyzed and a population linked effect pharmacokinetic/pharmacodynamic (PK/PD) model was developed to describe the local histamine response. The model consisted of a one-compartment PK model and a direct-response fractional maximum effect (Emax) model. The parameter estimates were obtained as follows: absorption rate constant (ka), 0.094/min; absorption lag time (Tlag), 2.72 min; partitioning clearance from local depot to systemic circulation (CLpar), 0.0006 L/min; baseline effect (E0), 13.1 flux unit; Emax, 13.4; concentration at half maximum effect (EC50) 31.1 mg/L. Covariate analysis indicated that age and race had significant influence on Tlag and EC50, respectively.

Pharmacokinetic properties and safety profile of histamine dihydrochloride injection in Chinese healthy volunteers: a phase I, single-center, open-label, randomized study.

PURPOSE: Histamine dihydrochloride (HDC) injection has been approved in Europe for the treatment of adults with acute myeloid leukemia, used in combination therapy with the T-cell-derived cytokine interleukin-2. Despite years of clinical applications of HDC in Europe, no data are available on its tolerability and pharmacokinetic properties in Chinese patients. The objective of this study was to determine the safety profile and pharmacokinetic properties of HDC in Chinese healthy volunteers (HVs). METHODS: In this Phase I, single-center, open-label, randomized study, 20 Chinese HVs were randomized to receive a single dose of 0.5 or 1.0 mg HDC via a 10-minute subcutaneous injection. Whole-blood and urine samples were collected at designated time points after dosing. Plasma and urine concentrations of histamine and metabolite N-methyl histamine were measured using a validated HPLC-MS/MS method. Pharmacokinetic parameters were estimated through noncompartmental procedures based on concentration-time data. Adverse events and evaluation of clinical laboratory tests were used to assess the safety profile. The pharmacokinetic profile for a single-dose of 1.0 mg HDC in Chinese HVs was compared with that in Western HVs. FINDINGS: No severe adverse events occurred in this study, and the severity of all adverse events was grade I according to the Common Terminology Criteria for Adverse Events, version 4.0. For the pharmacokinetic parameters of histamine at the 0.5-mg and 1.0-mg dose levels, t½ was 0.50 and 1.02 hours; Tmax was 0.15 and 0.14 hours; mean Cmax was 26.59 and 71.01 nmol/L; AUC0-t was 8.35 and 20.43 nmol/h/L; AUC0-∞ was 9.61 and 22.69 nmol/h/L; accumulated amount excreted in urine within 24 hours was 125.93 and 145.52 nmol; and maximum urine excretion rates were 21.85 and 38.94 nmol/h, respectively. For N-methyl histamine at the 0.5-mg and 1.0-mg dose levels, t½ was 0.58 and 0.66 hours; Tmax was 0.28 and 0.26 hours; mean Cmax was 17.01 and 23.54 nmol/L; AUC0-t was 7.72 and 17.08 nmol/h/L; AUC0-∞ was 9.01 and 19.62 nmol/h/L; accumulated amount excreted in urine within 24 hours was 331.7 and 583.21 nmol; and maximum urine excretion rates were 53.29 and 133.53 nmol/h, respectively. IMPLICATIONS: Both single-dose 0.5 mg and 1.0 mg HDC were well tolerated in Chinese HVs, and the pharmacokinetic profile of HDC in Chinese HVs was characterized in this study. A single dose of 1.0 mg HDC had a more rapid but similar extent of absorption, a wider distribution, and a little more rapid elimination in Chinese HVs compared with Western HVs. Findings from this study support additional clinical trials for HDC using in Chinese patients. Chinese Clinical Trial Registry identifier: ChiCTR-ONC-13003954.

Variability of histamine pharmacodynamic response in children with allergic rhinitis.

Histamine iontophoresis with laser Doppler monitoring (HILD) is a robust and dynamic surrogate for histamine microvasculature response. We characterized histamine pharmacodynamics in children using HILD. HILD was performed in 54 children with allergic rhinitis. A non-compartmental analysis and non-linear mixed-effects model with a linked effect PK/PD model was used to provide estimates for area under the effect curve (AUEC), maximal response over baseline (EffmaxNT), and time of EffmaxNT (Tmax). Data were placed in sub-groups by visualization of time vs. response relationships. ANOVA and regression analyses were used for sub-group comparisons. Three histamine response phenotypes were identified. One group demonstrated a hyper-responsive phenotype (higher Tmax, EffmaxNt and AUEC, P < .01). AUEC and EffmaxNT were more strongly associated in this group (r(2) = 0.86) than the entire cohort (r(2) = 0.64). These data demonstrate a hyper-responsive histamine phenotype via HILD. This finding is important to future pharmacologic studies of antihistamines.

Photodynamic treatment of oral squamous cell carcinoma in hamster cheek pouch model using chlorin p6-histamine conjugate.

BACKGROUND: Over-expression of histamine receptors has been reported in several types of malignancies. Earlier we have successfully demonstrated use of chlorin p6-histamine conjugate (Cp6-his) for improving cellular uptake and photo toxicity of Cp6 in oral cancer cell lines. In the present study, after having confirmed that histamine receptors are over-expressed in tumors of hamster cheek pouch, we investigated the efficacy of Cp6-his for photodynamic treatment (PDT) of tumors in this animal model. METHODS: Cp6-his (3mg/kg body weight) was injected intraperitoneally and its accumulation in tumor, surrounding tissue, normal mucosa and abdominal skin was monitored non-invasively by fluorescence spectroscopy. For PDT, tumors at 4h after Cp6-his administration were exposed to red light (660±25nm, 100J/cm(2)). Tumor damage and regression were assessed by histology and tumor volume measurements, respectively. Expression of histamine H2 receptors in tumor and normal mucosa was assessed by immuno-staining. RESULTS: The accumulation of Cp6-his was higher in tumors as compared to normal mucosa at 4h after its administration. For Cp6 similar preferential accumulation was observed except that in normal mucosa the accumulation of Cp6 was more as compared to Cp6-his. The clearance of Cp6-his from skin was rapid showing ∼80% decrease within 48h from its peak level at 4h after drug injection. PDT led to extensive cellular damage and tumors of size up to ∼1000mm(3) regressed completely one week after PDT. CONCLUSION: Higher tumor selectivity of Cp6-his and complete regression of bigger tumors after PDT suggest that conjugating Cp6 to histamine is a promising approach to improve PDT efficacy.

A study of 131iodine-labeling of histamine-indomethacin: its in vivo therapeutic effect and anti-tumor mechanisms in Lewis-bearing lung cancer.

BACKGROUND: In our research,we study the effect of 131iodine-labeled histamine-indomethacin (131I-His-IN). We focus on its in vivo therapeutic effect and anti-tumor mechanisms in Lewis-bearing lung cancer. METHODS: 131I-His-IN was administered by garage to the mice. At different timepoints, we made autoradiography (ARG) slices to observe the distribution of 131I-His-IN in the cellular, and the sliced samples underwent hematoxylin and eosin (HE) staining for observation of tumor necrosis. Before treatment, the groups of mice underwent 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) scans ,and they were then given physiologic saline, iodine 131 (131I), indomethacin (IN), Histamine-indomethacin (His-IN), and 131I-His-IN, respectively, three times daily for seven days. Seven days later, all the mice underwent 18F-FDG PET-CT scans again. We calculated the maximum standard uptake value (SUVmax) of the region of interest (ROI) and tumor inhibition rate at the same time. RESULTS: In ARG groups, black silver particle was concentrated in the nucleus and cytoplasm. 131I-His-IN mainly concentrated in tumor tissues. At 8 hours after 131I-His-IN, the radioactivity uptake in tumor tissue was higher than in other organs (F=3.46, P<0.05). For the 18F-FDG PET-CT imaging, the tumor tissuses SUVmax of the ROI was lower compared to other groups after the treatment with 131I-His-IN. The tumor inhibitory rate (54.8%) in 131I-His-IN group was higher than in other groups, too. In the 131I-His-IN group the vascular endothelial growth factor (VEGF) decreased gradually compared to other groups. The tumor tissue necrotized obviously in 131I-His-IN group. CONCLUSIONS: Through these animal experiments, we found 131I-His-IN could inhibit the Lewis lung cancer cells. 131I-His-IN focused at the cell nucleus and cytoplasm. It could reduce VEGF and increase tumor inhibitory rate. At the same time, 18F-FDG PET-CT scan could be used for a curative effect and monitoring of disease prognosis.

Modulation of biogenic amines content by poly(propylene imine) dendrimers in rats

Biogenic amines and polyamines participate in all vital organism functions, their levels being important function determinants. Studies were performed to check whether repeated administration of poly(propylene imine) (PPI) dendrimers, synthetic macromolecules with diaminobutane core, and peripheral primary amine groups, may influence the endogenous level of amines, as represented by the two of them: spermidine, a natural derivative of diaminobutane, and histamine. The experiment was carried out on Wistar rats. Fourth generation PPI dendrimer, as well as maltotriose-modified fourth generation PPI dendrimers with (a) cationic open sugar shell and (b) neutral dense sugar shell that possess a higher biocompatibility, was used. Applying the combination of column chromatography on Cellex P and spectrofluorimetric assays of o-phthaldialdehyde, the final amine condensation products were employed to analyze tissue spermidine and histamine outside the central nervous system. Furthermore, radioenzymatic assay was used to measure histamine levels in the brain. The obtained results indicate that in some tissues, the endogenous concentrations of histamine and spermidine may be affected by dendrimers depending on their dose and type of dendrimers (AU)

Development and validation of a sample stabilization strategy and a UPLC-MS/MS method for the simultaneous quantitation of acetylcholine (ACh), histamine (HA), and its metabolites in rat cerebrospinal fluid (CSF).

A UPLC-MS/MS assay was developed and validated for simultaneous quantification of acetylcholine (ACh), histamine (HA), tele-methylhistamine (t-mHA), and tele-methylimidazolacetic acid (t-MIAA) in rat cerebrospinal fluid (CSF). The biological stability of ACh in rat CSF was investigated. Following fit-for-purpose validation, the method was applied to monitor the drug-induced changes in ACh, HA, t-mHA, and t-MIAA in rat CSF following administration of donepezil or prucalopride. The quantitative method utilizes hydrophilic interaction chromatography (HILIC) Core-Shell HPLC column technology and a UPLC system to achieve separation with detection by positive ESI LC-MS/MS. This UPLC-MS/MS method does not require extraction or derivatization, utilizes a stable isotopically labeled internal standard (IS) for each analyte, and allows for rapid throughput with a 4 min run time. Without an acetylcholinesterase (AChE) inhibitor present, ACh was found to have 1.9±0.4 min in vitro half life in rat CSF. Stability studies and processing modification, including the use of AChE inhibitor eserine, extended this half life to more than 60 min. The UPLC-MS/MS method, including stabilization procedure, was validated over a linear concentration range of 0.025-5 ng/mL for ACh and 0.05-10 ng/mL for HA, t-mHA, and t-MIAA. The intra-run precision and accuracy for all analytes were 1.9-12.3% CV and -10.2 to 9.4% RE, respectively, while inter-run precision and accuracy were 4.0-16.0% CV and -5.3 to 13.4% RE, respectively. By using this developed and validated method, donepezil caused increases in ACh levels at 0.5, 1, 2, and 4h post dose as compared to the corresponding vehicle group, while prucalopride produced approximately 1.6- and 3.1-fold increases in the concentrations of ACh and t-mHA at 1h post dose, respectively, compared to the vehicle control. Overall, this methodology enables investigations into the use of CSF ACh and HA as biomarkers in the study of these neurotransmitter systems and related drug discovery efforts.

A study of ¹³¹iodine labeling of indomethacin, its in vivo biological distribution in Lewis-bearing lung cancer, and its induction of apoptosis in lung cancer.

OBJECTIVE: To study the synthesis of 131iodine (I) labeled histamine-indomethacin (His-IN), its in vivo distribution in Lewis-bearing mice, and its effects on suppression of Lewis lung cancer growth and induction of apoptosis. METHODS: The present study was carried out in the Experimental Research Center, Sheng Jing Hospital of China Medical University Hospital, Shenyang China between December 2008 and October 2009. Chemical synthesis of His-IN was carried out. Ninety-five C57 mice were allocated into 12 groups, and a series of experiments including the in vivo biological distribution of 131I-His-IN in C57 mice bearing Lewis lung cancer was explored, and the therapeutic effects of IN and 131I-His-IN in lung cancer-bearing mice were assessed through tumor suppression experiments, flow cytometry, and detection of tumor necrosis factor. RESULTS: The 131I-His-IN radionuclide count ratio of the tumor site and surrounding region significantly increased with time, namely, the retention time of 131I-His-IN radionuclide was longer in the tumor site. A 3.0 mg/kg and 3.5 mg/kg 131I-His-IN, as well as 3.0 mg/kg and 3.5 mg/kg IN all had tumor suppression and apoptosis induction effects on tumors, among which the 3.5 mg/kg 131I-His-IN group had significant differences compared with all other groups. CONCLUSION: The 131I-His-IN not only retains the tumor-affinity property of IN, the synergistic effect of these 2 also enhances the tumor suppression and pro-apoptotic function.

Conjugation of chlorin p(6) to histamine enhances its cellular uptake and phototoxicity in oral cancer cells.

PURPOSE: Our previous studies in hamster cheek pouch model have shown that chlorin p (6) (Cp (6)), a chlorophyll derivative is a suitable photosensitizer for photodynamic treatment (PDT) of small tumors (<5 mm). However, for bigger tumors, the accumulation of Cp (6) was inadequate, which compromised the effectiveness of PDT. The purpose of present study was to investigate the possibility of improving the cellular uptake of Cp (6) by conjugating it to histamine, a biogenic amine that is known to modulate tumor growth and development via cell surface receptors. METHODS: The conjugate of Cp (6) and histamine (Cp (6)-his) was prepared by carbodiimide coupling reaction. Cellular uptake, intracellular localization and cytotoxicity of both Cp (6) and its conjugate were investigated in two human oral cancer cell lines (4451 and NT8e). The percentage of necrotic and apoptotic cells after PDT were also estimated using Hoechst 33342-propidium iodide staining. RESULTS: In both the cell line, the cellular uptake of Cp (6)-his was found to be ~10 times higher when compared to Cp (6). Histamine led to a slight increase in intracellular uptake of Cp (6)-his, whereas ranitidine, a histamine H2 receptor antagonist, and incubation at lower temperature (~15°C) led to its inhibition, suggesting that uptake of Cp (6)-his is receptor mediated. Results on western blot confirmed the presence of H2 receptor in both the cell line. Observations on intracellular localization revealed that unlike Cp (6), which localized on multiple sites, Cp (6)-his showed localization on the cell membrane and around the perinuclear region. Moreover, the phototoxicity induced by Cp (6)-his was ~4 times higher when compared to Cp (6) in both the cell lines. There was, however, no significant difference in the mode of cell death. CONCLUSION: Results suggest that conjugating Cp (6) with histamine can help improve the effectiveness of PDT in oral cancer cells by enhancing its intracellular delivery.

Functional analysis of human organic cation transporter OCT3 (SLC22A3) polymorphisms.

We analyzed the functional properties of five single nucleotide polymorphisms (SNPs) in organic cation transporter OCT3 gene (SLC22A3) resulting in the amino acid changes with a transient expression system. Three SNPs (A116S, T400I, and A439V) exhibited reduced uptake of both [(3)H]histamine and [(3)H]MPP(+), although their protein expressions were detected in the plasma membrane of transfected cells. This study suggests that the OCT3 variants will contribute to inter-individual variations leading to the differences in cationic drug disposition as well as certain disease processes such as hypertension, allergic diseases, and neuropsychiatric diseases by the clearance of endogenous organic cations such as biogenic amines.

Histamine (re)uptake by astrocytes: an experimental and computational study.

Astrocytes participate in the clearance of neurotransmitters by their uptake and subsequent enzymatic degradation. Histamine as a polar and/or protonated molecule must use a carrier to be transported across the cell membrane, although a specific histamine transporter has not been elucidated, yet. In this work we upgraded the kinetic studies of histamine uptake into neonatal rat cultured type 1 astrocytes with quantum chemical calculations of histamine pKa values in conjunction with Langevin dipoles solvation model as the first step toward microscopic simulation of transport. Our results indicate that astrocytes transport histamine by at least two carrier mediated processes, a concentration gradient dependent passive and a sodium-dependent and ATP-driven active transport. We also demonstrated that histamine protonation states depend on the polarity of the environment. In conclusion we suggest that histamine, a polar molecule at physiological pH uses at least two different mechanisms for its uptake into astrocytes -an electrodiffusion and Na(+)-dependent and ouabain sensitive active process. We emphasize relevance of knowledge of histamines protonation states at the rate limiting step of its transport for microscopic simulation that will be possible when structure of histamine transporter is known.

Efecto del clorhidrato de mianserina sobre preparaciones de órgano aislado de cobaya y de rata "in vitro" / Effects of mianserin hydrochloride on isolated organ preparations of guinea-pig and rat "in vitro"

OBJETIVO. Estudiar las modificaciones inducidas por Mianserina en las respuestas del ileon aislado de cobaya a acetilcolina e histamina, conducto deferente de rata a noradrenalina y útero aislado de rata a histamina. MATERIAL Y MÉTODOS. Se utilizó ileon aislado de cobaya incubado en solución de Tyrode, conducto deferente de rata incubado en solución de Krebs- Henseleit y útero aislado de rata incubado en solución de Jalón. Se realizaron curvas dosis-efecto a acetilcolina, histamina y noradrenalina en ausencia y en presencia de mianserina y se calculó el pA2. RESULTADOS. La mianserina se comporta como antagonista de los neurotransmisores estudiados. Conclusión: La mianserina se comporta como fármaco escasamente estabilizador inespecífico de membrana (AU)

OBJETIVE. Study the modifications produced by mianserin in the responses of isolated guinea-pig to acetylcholine and histamine, rat vas deferens to noradrenalinee and rat uterus to histamine. MATERIAL AND METHODS. Guinea-Pig ileum incubated in Tyrode solution were used. Dose-effect curves to acetylcholine and histamine were made in absence and in the presence of mianserin. Rat vas deferens incubated in Krebs-Henseleit solution were used. Dose-effect curves to noradrenaline were made in absence and in the presence of mianserin. Uterus of rat incubated in Jalon solution were used. Dose-effect curves to histamine were made in absence and in the presence of mianserin, pA2 was calculated. RESULTS. Mianserin behave as antagonist of acethylcholine, histamine and noradrenaline. Conclusions: Mianserin acts as few unspecific membrane stabilizer (AU)

Efecto de amoxapina en preparaciones de órgano aislado de cobaya y de rata "in vitro" / Effect of amoxapine on severa preparations of isolated guinea-pig and rat organ "in vitro"

OBJETIVO. Estudiar las modificaciones inducidas por amoxapina en las respuestas del íleon aislado de cobaya a acetilcolina e histamina, conducto deferente de rata a noradrenalina y dopamina y útero aislado de rata a histamina. MATERIAL Y MÉTODOS. Se utilizó ileon aislado de cobaya incubado en solución de Tyrode, conducto deferente de rata incubado en solución de Krebs-Henseleit y útero aislado de rata incubado en solución de Jalón. Se realizaron curvas dosis-efecto a acetilcolina, histamina, noradrenalina y dopamina en ausencia y en presencia de amoxapina y se calcularon los valores de pA2 y pD'2. RESULTADOS. La amoxapina se comporta como antagonista de los neurotransmisores estudiados. CONCLUSIONES. La amoxapina se comporta como estabilizador inespecífico de membrana (AU)

OBJETIVE. Study the modifications produced by amoxapine in the responses of isolated guinea-pig to acetylcholine and histamine, rat vas deferens to noradrenaline and dopamine and rat uterus to histamine. MATERIAL AND METHODS. Guinea-pig incubated in Tyrode solution were used. Dose-effect curves to acetylcholine and histamine were made in absence and in the presence of amoxapine. Rat vas deferens incubated in Krebs-Henseleit solution were used. Dose-effect to noradrenaline and dopamine were made in the absence and in the presence of amoxapine. Uterus of rat incubated in Jalon solution were used. Dose-effect curves to histamine were made in the absence and in the presence of amoxapine. pA2 and pD'2 were calculated. RESULTS. Amoxapine behave as antagonist of acetylcholine, histamine and dopamine. CONCLUSIONS. Amoxapine acts as unspecific membrane stabilizer (AU)

Efectos de citalopram, reboxetina y nefazondona sobre diversas preparaciones de órgano aislado de cobaya y de rata "in vitro" / Effectos of citalopram, reboxetine and nefazodone in differentes tissues form guinea-pig and rat "in vitro"

El citalopram, la reboxetina y la nefazodona son fármacos antidepresivos que fundamentalmente inhiben la recaptación neuronal de serotonina, aunque se han descrito otras interacciones. Se estudian los efectos de citalopram, reboxetina y nefazodona sobre noradrenalina (NA), dopamina (DA) o potasio (K+) en conducto deferente de rata; histamina (H), acetilcolina (Ach), 4-aminopiridina (4-AP) y potasio en ileon aislado de cobaya y serotonina (5-HT), oxitocina y potasio en útero aislado de rata. Se utilizó solución de Krebs-Henseleit con o sin adición de cocaína, 17-beta estradiol y propranolol, para el conducto deferente aislado de rata, solución de Jalón para el útero de rata y solución de Tyrode para el ileon aislado de cobaya. Cuando fue posible se calcularon los valores de pD'2. CONCLUSIONES: El citalopram inhibe las contracciones inducidas por Ach (pD'2 = 4.3 ± 0.3), H (pD'2 = 5.3 ± 0.4), 4-AP (pD'2 = 5.4 ± 0.4) y potasio (pD'2 = 4.3 ± 0.3) en ileon aislado de cobaya; 5-HT (pD'2 = 3.5 ± 0.3), oxitocina (pD'2= 4.8 ± 0.3) y potasio (pD'2= 4.2 ± 0.3) en útero de rata. La reboxetina inhibe las contracciones inducidas por 5-HT (pD'2= 5.1 ± 0.4), oxitocina (pD'2= 4.9 ± 0.3) y potasio (pD'2= 5.1 ± 0.4) en útero de rata y DA (pD'2= 4.6 ± 0.4 en conducto deferente aislado de rata. La nefazodona inhibe las contracciones inducidas por Ach (pD'2= 5.3 ± 0.3), H (pD'2 = 5.3 ± 0.4), 4-AP (pD'2 = 5.2 ± 0.3) y potasio (pD'2 = 5.2 ± 0.4) en ileon aislado de cobaya; 5-HT (pD'2 = 7.0 ± 0.5), oxitocina (pD'2 = 5.2 ± 0.4) y potasio (pD'2 = 5.2 ± 0.4) en útero de rata; NA (pD'2 = 2.4 ± 0.1), DA (pD'2 = 5.2 ± 0.4) y potasio (pD'2 = 4.4 ± 0.4) en conducto deferente aislado de rata. Otras interacciones no son estadísticamente significativas (AU)

Citalopram, reboxetine and nefazodone are antidepressants which mainly inhibit serotonin (5-HT) reuptake, other interactions have been described. Therefore, the effects of citalopram, reboxetine and nefazodone on noradrenaline (NA), dopamine (DA), or K+ - contracted rat vas deferens have studied. The effects on 5-HT, oxytocin and K+-induced contractions in rat uterus and those on histamine (H), acetylcholine (Ach), 4-aminopyridine (4-AP) and K+-contractions in guinea-pig ileum were also studied. Krebs-Henseleit solution with and without adding cocaine, 17 beta estradiol and propranolol was used for rat vas deferens tissues. Jalon solution for rat uterus and Tyrode solution for guinea-pig ileum. When possible pD'2 values were calculated. CONCLUSIONS: Citalopram inhibited contractions induced by Ach (pD'2 = 4.3 ± 0.3), H (pD'2 = 5.3 ± 0.4), 4-AP (pD'2 = 5.4 ± 0.4), and potassium (pD'2 = 4.3 ± 0.3) in guinea-pig ileum; 5-HT (pD'2 = 3.5 ± 0.3), oxytocin (pD'2 = 4.8 ± 0.3) and potassium (pD'2 = 4.2 ± 0.3) in rat uterus. Reboxetine inhibited contractions induced by 5-HT (pD'2 = 5.1 ± 0.4), oxytocin (pD'2 = 4.9 ± 0.3) and potassium (pD'2 = 5.1 ± 0.4) in rat uterus; DA (pD'2 = 4.6 ± 0.4) in rat vas deferens. Nefazodone inhibited contractions induced by Ach (pD'2 = 5.3 ± 0.3), H (pD'2 = 5.3 ± 0.4), 4-AP (pD'2 = 5.2 ± 0.3) and potassium (pD'2 = 5.2 ± 0.4) in guinea-pig ileum; 5-HT (pD'2 = 7.0 ± 0.5), oxytocin (pD'2 = 5.2 ± 0.4), and potassium (pD'2 = 5.2 ± 0.4) in rat uterus; NA pD'2 = 2.4 ± 0.1), DA (pD'2 = 5.2 ± 0.4) and potassium (pD'2 = 4.4 ± 0.4) in rat vas deferens. Other interactions were not statistically significant (AU)

Histamine dihydrochloride for the treatment of acute myeloid leukemia, malignant melanoma and renal cell carcinoma.

Histamine dihydrochloride is a vasoactive biogenic amine. It inhibits the reactive oxygen species formation in monocytes via histamine H2 receptors and protects natural killer and T cells from oxidative damage. Histamine has the potential to optimize cytokine-induced activation of T cells and natural killer cells; therefore, the addition of histamine to cytokine treatment may improve treatment efficacy. Clinical trials in solid tumors and in acute myeloid leukemia have demonstrated the potential to improve treatment outcome when histamine dihydrochloride is combined with immunotherapy. In patients with metastatic malignant melanoma, this strategy improved remission rates and increased survival. On the other hand, less promising results were reported for histamine dihydrochloride added to cytokines in patients with other solid tumors, especially in advanced renal cell carcinoma. A recent international Phase III trial performed in 320 patients showed that maintenance therapy with histamine dihydrochloride and IL-2 was able to improve leukemia-free survival in patients with acute myeloid leukemia, without an effect on overall survival. The combination of histamine dihydrochloride with IL-2 potentially offers an efficacious and tolerable maintenance strategy for patients with acute myeloid leukemia; however, its impact on survival remains to be explored.

Sonotubometry: a useful tool to measure intra-individual changes in eustachian tube ventilatory function.

OBJECTIVE: To determine whether intra-individual changes in eustachian tube (ET) function induced by local application of a histamine phosphate solution can be detected using an improved sonotubometer. DESIGN: The function of the ET was measured with a revised sonotubometer before and after histamine was applied to the nasopharyngeal ostium of the ET. SETTING: Tertiary referral hospital. PATIENTS: Twenty-five otologically healthy adults. INTERVENTIONS: A histamine phosphate solution with a concentration of 16 mg/mL was applied to the nasopharyngeal ostium of the ET using a pressure nebulizer. MAIN OUTCOME MEASURES: The number of openings during 10 acts of swallowing. This outcome value could range from 0 to 10. The number of ET openings before and after histamine application was compared. RESULTS: The mean number of ET openings dropped dramatically: from 8.4 before application of histamine to 2.7 after application. This difference was statistically significant; there was a mean difference of 5.6 (95% confidence interval, 4.4-6.9; P < .001). CONCLUSION: Sonotubometry is capable of detecting intra-individual changes in ET function and may therefore be a very useful tool in monitoring and/or clinical research of ET dysfunction or function.

Resin-packed nanoelectrospray in combination with video and mass spectrometry for the direct and real-time molecular analysis of mast cells.

A nano-electrospray ionization (nanoESI) emitter for analysis of a biological solution was developed by packing a nanoESI needle with two types of resins for desalting and preconcentration of target molecules. Determination of secreted histamine and serotonin molecules in cell culture buffers was demonstrated using 5-methyltryptamine as internal standard. The results showed good linearity of target signals in the concentration range from 0.25 to 50.0 ng/mL of histamine or serotonin. These molecules were monitored to be secreted by A23187 (calcium ionophore) stimulant in rat peritoneal mast cells. Using a combination of a video-microscope and a mass spectrometer, we could visualize exocytotic moments and analyze secreted molecules by mass spectrometry simultaneously. Time-dependent release of histamine and serotonin from activated mast cells showed that significant production of these molecules occurred and reached a maximal level at 15 min for serotonin and at 30 min for histamine, respectively. These results showed that this method allows the direct and timely analysis of secreted molecules in biological responses.

Evidence for the presence of histamine uptake into the synaptosomes of rat brain.

Histamine has many physiological roles in the brain and periphery. Neuronal histamine is metabolized almost exclusively by histamine N-methyltransferase. Although several neurotransmitter systems such as dopamine and 5-hydroxytryptamine have their specific reuptake system in their neurons and glial cells, a specific histamine reuptake system into the corresponding nerve terminals or glial cells has not yet been clearly elucidated. We characterized the uptake of histamine into the P2 fractions of rat brain homogenized in 0.32 mol/l sucrose using in vitro uptake techniques. [3H]histamine uptake increased with the increment of added protein amount and elapsed time. [3H]histamine uptake was also temperature-dependent. The uptake of [3H]histamine into the P2 fractions occurs by two saturable processes, a high-affinity and a low-affinity, characterized by K(m) values of 0.16 and 1.2 micromol/l, respectively. Na(+), Cl(-) and HCO(3)(-) ions were essential for the uptake of histamine in P2 fractions. [3H]histamine uptake was inhibited in the presence of several tricyclic antidepressants. In accordance with this, the endogenous release of histamine from brain slices evoked by 100 mmol/l K(+) was augmented in the presence of 20 micromol/l imipramine. These results further support the existence of a specific histamine uptake system in the brain, although the precise molecular entities have not been identified until now.