Combined Administration Of Low Doses Research Articles

Polydopamine-cloaked Fe-based metal organic frameworks enable synergistic multidimensional treatment of osteosarcoma

One of the major challenges in effective cancer therapy arises because of the hypoxic microenvironment in the tumor. This compromises the efficacy of both chemo- and radiotherapy, and thus hinders patient outcomes. To solve this problem, we constructed polydopamine (PDA)-cloaked Fe-based metal organic frameworks (MOFs) loaded with d-arginine (d-Arg), glucose oxidase (GOX), and the chemotherapeutic drug tirapazamine (TPZ). These offer simultaneous multifaceted therapy combining chemodynamic therapy (CDT)/radiotherapy (RT)/starvation therapy (ST)/gas therapy (GT) and chemotherapy. The particles further can act as contrast agents in magnetic resonance imaging. GOX catalyses the conversion of endogenous glucose and O2 to hydrogen peroxide and gluconic acid, blocking the cells’ energy supply and providing ST. With the resultant acidification of the local environment, the breakdown of the MOF releases TPZ (for chemotherapy) and Fe3+, which reacts with H2O2 to produce reactive oxygen species and thus stimulates the conversion of d-Arg to NO for GT and RT sensitization. The PDA coating not only seals the pores and chelates Fe3+ to enhance the T1-weighted magnetic resonance imaging (MRI) properties, but also is used to graft folate bovine serum albumin (FA-BSA) and thereby target the tumor site. The combined administration of low doses of X-ray irradiation and nanoparticles reduces the side effects on healthy tissue and can prevent lung metastases in mice. This work highlights the synergistic treatment of osteosarcoma via ST/GT/CDT/RT/MRI/ chemotherapy using a PDA-cloaked MOF system.

Abstract 3903: Role of the miR-301a/Fra-2/GLIPR1 axis in lung cancer cisplatin resistance

Abstract Lung cancer is the leading cause of cancer-related mortality in both men and women worldwide. Despite the administration of platinum compounds represents the main treatment, the majority of tumors remains intrinsically resistant. In lung cancer, miR-301a exerts a main role by modulating the activity of transcription factors like NF-kB and Stat3. Here, we dissected the contribution of miR-301a in the regulation of its new identified target Fos-related antigen-2 (Fra-2), a transcription factor that belongs to the Fos/AP-1 family. By microarray analysis, we discovered that Fra-2 overexpression increased glioma pathogenesis-related protein 1 (GLIPR1) levels, a mediator of cisplatin resistance in lung cancer. Its mechanism of regulation is still unclear. We demonstrated that GLIPR1 is also a miR-301a target. In vitro, modulation of miR-301a reduced Fra-2 and GLIPR1 levels; conversely, Fra-2 overexpression significantly increased GLIPR1 and miR-301a. Then, by chromatin immunoprecipitation assay, we confirmed that Fra-2 interacts with the promoter regions of both GLIPR1 and MIR301A genes, supporting that miR-301a/Fra-2/GLIPR1 axis could be autoregulated by feedback loop in which Fra-2 promotes the transcription of MIR301A gene. Investigating the effect of this new axis on the response to cisplatin, we observed that both Fra-2/GLIPR1 overexpression and miR-301a silencing induced cisplatin resistance in lung cancer cells. By contrast, silencing of GLIPR1 and combined administration of low doses of Fos/AP-1 inhibitor restored the cisplatin sensitivity in Fra-2 overexpressing cells. In the lung adenocarcinoma samples from the TCGA dataset, miR-301a overexpression inversely correlated with Fra-2 and GLIPR1 expression. Consistently, the overexpression of miR-301a identified a fraction of tumors with low expression of Fra-2 and GLIPR1 in an internal cohort of lung cancer samples. Altogether, our findings identify the miR-301a/Fra-2/GLIPR1 axis that contributes to cisplatin resistance in lung cancer cells and could serve as biomarker to stratify patients who may benefit from cisplatin administration, alone or in combination with Fos/AP-1 inhibitors. Citation Format: Francesca Lovat, Gian Luca Rampioni Vinciguerra, Marina Capece, Rosario Distefano, Giovanni Nigita, Andrea Vecchione, Carlo M. Croce. Role of the miR-301a/Fra-2/GLIPR1 axis in lung cancer cisplatin resistance. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3903.

Antidepressant-like effects of scopolamine in mice are enhanced by the group II mGlu receptor antagonist LY341495

Clinical studies have shown that the muscarinic receptor antagonist scopolamine induces a potent and rapid antidepressant effect relative to conventional antidepressants. However, potential undesirable effects, including memory impairment, partially limit the use of scopolamine in psychiatry. In the present study, we propose to overcome these limitations and enhance the therapeutic effects of scopolamine via administration in combination with the group II metabotropic glutamate (mGlu) receptor antagonist, LY341495. Joint administration of sub-effective doses of scopolamine (0.03 or 0.1 mg/kg, i.p.) with a sub-effective dose of LY341495 (0.1 mg/kg, i.p.) induced a profound antidepressant effect in the tail suspension test (TST) and in the forced swim test (FST) in mice. This drug combination did not impair memory, as measured using the Morris water maze (MWM), and did not influence the locomotor activity of mice. Furthermore, we found that an AMPA receptor antagonist, NBQX (10 mg/kg), completely reversed the antidepressant-like activity of a mixture of scopolamine and LY341495 in the TST. However, this effect was not influenced by para-chlorophenylalanine (PCPA) pre-treatment, indicating a lack of involvement of serotonergic system activation in the antidepressant-like effects of jointly given scopolamine and LY341495. Therefore, the combined administration of low doses of the antimuscarinic drug scopolamine and the group II mGlu receptor antagonist LY341495 might be a new, effective and safe strategy in the therapy of depression.

Study on inhibitory effect of combined administration of bear bile powder and cyclophosphamide on colorectal cancer liver metastasis by regulating tumor microenvironment

To explore the inhibitory effect of combined administration of bear bile powder (BBP) and cyclophosphamide (Cytoxan, CTX) on colorectal cancer liver metastasis by regulating tumor promotion inflammation microenvironment. The CRC liver metastasis mode in mice was established through in situ spleenic injection of SL4 tumor cells into spleens. The mice were randomly divided into 5 groups: the model group, the CTX (80 mg x kg(-1)) treatment group, the CTX + BBP high dose (300 mg x kg(-1)) group, the CTX + BBP middle dose (150 mg x kg(-1)) group and the CTX + BBP low dose (75 mg x kg(-1)) group. Mice were orally administered with drugs for 12 days, and sacrificed on the 13'h day for weighing their spleens and lives, HE staining, and immunofluorescence analysis. Their peripheral blood, and metastatic tumor in spleens and lives were analyzed with flow cytometry. Spleen and liver weights of the: CTX treatment group and other doses groups were significantly lower than that of the model group. HE staining and immunofluorescence analysis showed that lymphocyte infiltration was detected in normal tissues, and macrophages infiltration was observed around the tumor tissues. Flow cytometry analysis showed that the number of T-lymphocytes in peripheral blood of different doses groups were much higher than that of the CTX treatment group (P < 0.05), with the rise in the ratio of CD4/CD8; the total number of lymphocytes in spleen cell suspension increased in different doses groups, compared to the CTX treatment group, with notable increase in B cells (P < 0.05) and significant decrease in CD11b, F4/80 cells (P < 0.05). The combined treatment showed less monocyte macrophages in liver metastasis than that of the CTX treatment group. The combined treatment of bear bile powder and cyclophosphamide has the effect in not only protecting liver and increase immunity, but also in anti-inflammation and antitumor by regulating tumor microenvironment and reducing the collection of mononuclear macrophages. Particularly, the combined administration of low dose of bear bile powder and CTX shows the most significant effect in reducing inflammatory cell infiltration.

Abstract 9164: Low Doses of Ranolazine and Dronedarone in Combination Exert Potent Protection against Atrial Fibrillation and Vulnerability to Ventricular Arrhythmias during Acute Myocardial Ischemia

Background: Coronary artery disease carries dual risk for atrial fibrillation (AF) and sudden cardiac death. We examined whether low-dose ranolazine and/or dronedarone can protect against AF and vulnerability to ventricular tachyarrhythmias. Methods, Results: In chloralose-anesthetized, open-chest Yorkshire pigs (N=19), proximal segment of left circumflex (LCx) coronary artery was occluded to reduce flow by 75%. Electrode catheter was positioned on left atrial appendage to measure AF threshold (AFT) before and during LCx coronary artery stenosis prior to and at one hour after dronedarone (0.5 mg/kg i.v. bolus over 5 min) and/or ranolazine (0.6 mg/kg, i.v. bolus, followed by 0.035 mg/kg/min). Without drugs, LCx coronary artery stenosis lowered AFT from 25.2±1.7 control (mean±SEM) to 4.9±1.0 mA baseline (p&lt;0.01). At these low doses, neither ranolazine (plasma concentration: 2.4±0.6 μ M) nor dronedarone (plasma concentration: 20.9±3.5 nM) alone blunted ischemia-induced reduction in AFT, but combination was effective (from 25.2±1.7 control to 22.0±3.0 mA, NS). Combined but not separate administration blunted ischemia-induced surge in T-wave heterogeneity (TWH), a marker of risk for ventricular tachyarrhythmias. Without drug, TWH increased from 43.1±11.1 control to 149.7±15.1 μ V baseline during stenosis (p&lt;0.001); with both agents, TWH increased only from 61.7±13.7 control to 83.7±15.8 μ V during stenosis (NS) (Fig.). Conclusions: Combined administration of low doses of ranolazine and dronedarone exerts a potent, antiarrhythmic action consistent with synergy due to direct effects on myocardial electrical properties not on coronary flow, which was controlled.

Low doses of ranolazine and dronedarone in combination exert potent protection against atrial fibrillation and vulnerability to ventricular arrhythmias during acute myocardial ischemia

Coronary artery disease carries dual risk for atrial tachyarrhythmias and sudden cardiac death. To examine whether low-dose ranolazine and/or dronedarone can protect against vulnerability to atrial fibrillation (AF) and ventricular tachyarrhythmias. In chloralose-anesthetized, open-chest Yorkshire pigs (n = 15), the proximal segment of left circumflex (LCx) coronary artery was occluded to reduce flow by 75%. An electrode catheter was positioned on the left atrial appendage to measure AF threshold (AFT) before and during LCx coronary artery stenosis before and at 1 hour after dronedarone (0.5 mg/kg intravenous bolus over 5 minutes) and/or ranolazine administration (0.6 mg/kg intravenous bolus followed by 0.035 mg/kg/min). Before drug administration, LCx coronary artery stenosis lowered AFT from 25.2 ± 1.7 mA control (mean ± SEM) to 4.9 ± 1.0 mA baseline (P<.01). At the low doses, neither ranolazine (plasma concentration 2.4 ± 0.6 μM) nor dronedarone (plasma concentration 20.9 ± 3.5 nM) alone blunted the ischemia-induced reduction in AFT but were effective together (from 25.2 ± 1.7 mA control to 22.0 ± 3.0 mA during stenosis; P = not significant). AF duration (P<.03) and AF inducibility (P = .012) were reduced by ranolazine and dronedarone together but not by either drug alone. Concurrently, combined but not separate administration blunted the ischemia-induced surge in T-wave heterogeneity, a marker of risk for ventricular tachyarrhythmias (from 43.1 ± 11.1 μV control to 149.7 ± 15.1 μV during stenosis, P<.001, compared to 61.7 ± 13.7 μV control to 83.7 ± 15.8 μV during stenosis, P = not significant). Combined administration of low doses of ranolazine and dronedarone exerts a potent antiarrhythmic action on ischemia-induced vulnerability to AF and ventricular tachyarrhythmias due to direct effects on myocardial electrical properties.

Bortezomib Can Suppress Activation of Rapamycin-Resistant Memory T Cells Without Affecting Regulatory T-Cell Viability in Non-Human Primates

Memory T cells specific for donor antigens are currently recognized as a significant barrier for maintaining a successful transplant. Furthermore, it has been shown that commonly used immunosuppressive drugs do not alleviate this memory response. Here, we report that rapamycin allows significant proliferation of memory T cells and bortezomib can abrogate the proliferation of rapamycin-resistant memory T cells when preserving the survival of regulatory T cells. Peripheral blood mononuclear cells freshly isolated from non-human primates were stimulated with anti-CD3/CD28 antibodies, and inhibitory and apoptotic effects of rapamycin and bortezomib on memory T-cell proliferation were investigated. The CD95 marker in CD3+ T cells was used for the separate enrichment of memory T cells and naïve T cells. Rapamycin at the level even higher than therapeutic concentration could not suppress the proliferation of a significant proportion of memory T cells. However, the combined administration of bortezomib and rapamycin abrogated the proliferation of rapamycin-resistant memory T cells. Furthermore, bortezomib preserved the survival of preexisting CD4+ FoxP3+ regulatory T cells, while inducing apoptosis of CD4+ FoxP3- conventional T cells. The combined administration of low doses of rapamycin and bortezomib also exerted an additive effect on suppressing T-cell proliferation. Cytokine analysis demonstrated that bortezomib could not only suppress rapamycin-permissive interleukin (IL)-6 production, but also production of interferon (IFN)-gamma, IL-4, and IL-10. This article provides in vitro data from which immunosuppressive regimens for the effective control of memory T cells in non-human preclinical experiments and in clinical trials are selected.

Role of nociceptin/orphanin FQ and the pseudopeptide [Phe 1Ψ(CH 2NH)Gly 2]-nociceptin(1–13)-NH 2 and their interaction with classic opioids in the modulation of thermonociception in the land snail Helix aspersa

The role in nociception of nociceptin/orphanin FQ (N/OFQ) and its receptor, the opioid receptor-like 1 (NOP), remains unclear because this peptide has been implicated in both suppression and enhancement of nociception. The present work characterises the effects of N/OFQ and the NOP receptor antagonist, the pseudopeptide [Phe 1Ψ(CH 2NH)Gly 2]-nociceptin(1–13)-NH 2 (Phe 1Ψ), on thermonociception in the snail Helix aspersa using the hot plate assay. Additionally, the possible interaction of each of these compounds with morphine or dynorphin A 1–17 and naloxone was studied. Compounds were administered into the hemocoel cavity of H. aspersa and the latency to the aversive withdrawal behaviour recorded. Dose–response and time course curves were done. N/OFQ and naloxone produced a similar dose-dependent pronociceptive effect; however, N/OFQ reached its peak effect earlier and was 30 times more potent than naloxone. [Phe 1Ψ(CH 2NH)Gly 2]-nociceptin(1–13)-NH 2 and the opioid agonists, morphine and dynorphin A 1–17 produced antinociception with a similar efficacy, but [Phe 1Ψ(CH 2NH)Gly 2]-nociceptin(1–13)-NH 2 reached its peak effect more rapidly and lasted longer than that of dynorphin A 1–17 and morphine. [Phe 1Ψ(CH 2NH)Gly 2]-nociceptin(1–13)-NH 2 was 50 times less potent than dynorphin A 1–17, but 30 times more potent than morphine. N/OFQ significantly reduced morphine and dynorphin A 1–17-induced antinociception. Combined administration of low doses of [Phe 1Ψ(CH 2NH)Gly 2]-nociceptin(1–13)-NH 2 and morphine or dynorphin A 1–17 produced a potent antinociceptive effect. Sub-effective doses of naloxone and N/OFQ also synergised to produce pronociception. Data suggest that these two opioid classes regulate nociception through parallel systems. The H. aspersa model appears as a valuable experimental preparation to continue the study of these opioid receptor systems.

Endogenous opioids are involved in morphine and dipyrone analgesic potentiation in the tail flick test in rats

The combined administration of low doses of opiates with non-steroidal anti-inflammatory drugs can produce additive or supra-additive analgesic effects while reducing unwanted side effects. We have recently reported that co-administration of morphine with dipyrone (metamizol) produces analgesic potentiation both in naïve and in morphine-tolerant rats. The purpose of this work was to determine the role of opioids on the acute potentiation observed between morphine and dipyrone i.v. in the rat tail flick test. To do this, two experiments were done. In the first one, naloxone was administered 10 min before morphine (3.1 mg/kg), dipyrone (600 mg/kg) or their combination at the same doses. Control animals received saline instead of naloxone. In the second experiment, naloxone (or saline) was given 2 min after reaching the maximal peak effect with each individual analgesic treatment. When naloxone was i.v. administered prior to analgesics, it completely blocked morphine effects, partially prevented morphine/dipyrone antinociception and delayed dipyrone-induced nociception. At 3.1 mg/kg, naloxone produced an increased nociception. When naloxone was given after analgesics, it dose-dependently blocked the effects of morphine alone and in combination with dipyrone but with different potency in each case. As to dipyrone, naloxone delayed the time to antinociceptive peak effect. Taken together, these results support the notion that endogenous opioids are involved in the analgesic potentiation observed with the combination of morphine plus dipyrone.

Antiulcer effect of amlodipine and its interaction with H2blocker and proton pump inhibitor in pylorus ligated rats

<b>Objective:</b> To study the interaction between a calcium channel blocker, amlodipine, and antiulcer agents, famotidine and omeprazole, in pylorus ligation-induced gastric ulcers in rats.<br><b> Materials and Methods: </b> Gastric ulcers were induced in albino rats by pyloric ligation as described by Shay <i> et al</i> . Effects of different doses of amlodipine, famotidine and omeprazole on volume, pH, acidity of gastric secretion and ulcer index were observed. In addition, the effects of low dose of amlodipine in combination with low dose of famotidine or omeprazole on the above parameters were studied.<br><b> Results: </b> Amlodipine (0.5 mg and 1 mg/kg, i.p.), famotidine (4 mg/kg, i.p.) and omeprazole (4 mg/kg, i.p.) produced significant antiulcer effects. Low doses of famotidine (1 mg/kg, i.p.), omeprazole (1 mg/kg, i.p.) and amlodipine (0.25 mg/kg, i.p.) did not alter the above parameters significantly. Combined administration of low dose of amlodipine (0.25 mg/kg) and famotidine (1 mg/kg) showed significant antiulcer effects, which were apparent from the reduction in volume of gastric acid secretion, acidity and ulcer index with simultaneous increase in the intragastric pH. Similarly, low dose of omeprazole (1 mg/kg) when combined with low dose of amlodipine (0.25 mg/kg) also showed significant antiulcer effects.<br><b> Conclusion: </b> Amlodipine produced significant antiulcer effects in pylorus-ligated model. Combination of low doses of amlodipine with low doses of either famotidine or omeprazole produced significant antiulcer effects. It is suggested that the patients who received amlodipine therapy for some other clinical conditions are less prone to develop peptic ulcers; and even if ulcers develop, they would require lower doses of antiulcer agents like famotidine and omeprazole.

Impact of NO on ET-1- and AM-induced inotropic responses: potentiation by combined administration.

We characterize herein the impact of myocardial nitric oxide (NO) synthesis on the inotropic response to two cardioactive peptides, endothelin-1 (ET-1) and adrenomedullin (AM). In the isolated perfused rat heart preparation, intracoronary infusion of AM (0.03 and 1 nmol/l) and ET-1 (0.08 and 1 nmol/l) for 30 min induced a dose-dependent, gradual increase in developed tension, the maximal responses being equal. Inhibition of myocardial NO synthase (NOS) by N(omega)-nitro-L-arginine methyl ester (L-NAME; 300 micromol/l) enhanced the inotropic response to ET-1 at a concentration of 1 nmol/l; meanwhile, the effect of AM was not augmented significantly. The inotropic response to simultaneous administration of low, equipotent doses of AM (0.03 nmol/l) and ET-1 (0.08 nmol/l) was significantly smaller than that of either peptide alone. This depressed response was more than overcome by concomitant administration of L-NAME. In conclusion, this study reveals that the maximal inotropic response to ET-1 can be augmented by inhibition of myocardial NOS, whereas it has only a minor impact on the effect of AM. The inotropic response to combined administration of low doses of AM and ET-1 is substantially suppressed by endogenous NO, whereas the individual effects of the peptides at these doses are not the subject of secondary modulation by NO.

Effects of combined low dose of the isoflavone derivative ipriflavone and estrogen replacement on bone mineral density and metabolism in postmenopausal women

Objectives: To assess the pattern of biochemical markers of bone metabolism and vertebral bone mineral density in early postmenopausal women treated with combined ipriflavone and low dose conjugated estrogens. Methods: Bone biochemical markers and vertebral bone density were evaluated in a longitudinal, comparative, 2 year study conducted in postmenopausal women treated with sole calcium supplementation (500 mg/day), or with either ipriflavone (IP) at the standard dose (600 mg/day) plus the same calcium dose, low dose conjugated estrogens (CE) (0.3 mg/day) plus calcium, or low dose IP (400 mg/day) plus low dose CE (0.3 mg/day) plus calcium. The results were analyzed by repeated measures analysis of variance, as appropriate. Results: No modifications of both urinary excretion of hydroxyproline and plasma osteocalcin levels were observed in calcium and in CE-treated women, while vertebral bone density significantly decreased ( P < 0.0001) in both groups. In IP or IP + CE-treated women, plasma osteocalcin did not show any modification, while urinary hydroxyproline showed a significant ( P < 0.05) decrease, that paralleled a significant ( P < 0.05) increase in vertebral bone density. Conclusion: Postmenopausal IP administration, at the standard dose of 600 mg/day, can prevent the increase in bone turnover and the decrease in bone density that follow ovarian failure. The same effect can be obtained with the combined administration of low dose (400 mg/day) IP with low dose (0.3 mg/day) CE.

Role of NMDA and AMPA glutamatergic transmission in spinal c-fos expression after urinary tract irritation.

Chemical irritation of the lower urinary tract (LUT) of the rat increases the expression of the immediate early gene c-fos within neurons in the dorsal horn (DH), dorsal commissure (DCM), and intermediolateral region, including sacral parasympathetic nucleus (SPN) of the spinal cord (L6-S1). A previous study indicated the involvement of the N-methyl-D-aspartic acid (NMDA) receptor in this c-fos expression after LUT irritation. The role of glutamatergic synapses was further investigated using a selective and competitive alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor antagonist (LY-215490). Systemic administration of LY-215490 produced a dose-dependent decrease in the number of Fos-positive cells after LUT irritation in the DCM and SPN areas, whereas in the DH only the highest dose (10 mg/kg) of LY-215490 decreased the number of Fos-positive cells. A low dose (1 mg/kg) of either MK-801 (an NMDA antagonist) or LY-215490 alone did not alter c-fos expression. However, a combined administration of low doses of MK-801 and LY-215490 significantly decreased the number of Fos-positive cells in all regions of the spinal cord. These results indicate that AMPA as well as NMDA receptors are involved in the spinal processing of nociceptive input from the LUT and that these glutamatergic receptors play a synergistic role in visceral nociceptive processing.

Interactions of constitutive nitric oxide with PAF and thromboxane on rat intestinal vascular integrity in acute endotoxaemia

1. The involvement of endogenous platelet activating factor (PAF) and thromboxane A2 in the acute microvascular damage in the ileum and colon induced by the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) following endotoxin administration was investigated in the rat over a 1 h period. 2. Administration of L-NAME (1-10 mg kg-1, s.c.) concurrently with E. coli lipopolysaccharide (LPS; 3 mg kg-1, i.v.) dose-dependently increased vascular permeability in the ileum and colon, as determined by the leakage of radiolabelled albumin, and caused macroscopic mucosal damage in the ileum determined 1 h later. Neither LPS administration nor L-NAME (5 mg kg-1) alone affected resting vascular permeability. 3. Infusion of phenylephrine (10 micrograms kg-1 min-1, i.v. for 1 h) caused an elevation in blood pressure similar to that found following L-NAME administration (5 mg kg-1, i.v. or s.c.), but did not increase intestinal vascular permeability, when administered with LPS (3 mg kg-1, i.v.). 4. The increased vascular permeability in the ileum and colon and macroscopic damage in the ileum, induced by L-NAME (5 mg kg-1, s.c.) and LPS (3 mg kg-1, i.v.) was dose-dependently inhibited following s.c. pretreatment (15 min before challenge) with the thromboxane synthase inhibitors, OKY 1581 (5-25 mg kg-1) or 1-benzyl-imidazole (1-50 mg kg-1), or with the thromboxane receptor antagonist, BM 13177 (0.2-2 mg kg-1). 5. Pretreatment with the cyclo-oxygenase inhibitor, indomethacin (2-5 mg kg-', s.c., 15 min before challenge) reduced the microvascular injury in the ileum and colon and macroscopic lesions in the ileum,observed after the concurrent administration of L-NAME and LPS.6. Pretreatment (15 min) with the PAF-receptor antagonists, WEB 2086 (0.5-1 mg kg-', s.c.) or BN52021 (2.5-10 mg kg-', s.c.) likewise attenuated this intestinal vascular injury.7. Combined administration of low doses of l-benzyl-imidazole (1 mg kg-') with WEB 2086(0.5 mg kg-')15 min before L-NAME and LPS challenge, abolished this vascular damage and macroscopic injury.8. These results suggest that PAF and thromboxane A2 are released acutely following challenge with a low dose of endotoxin. However, these mediators do not appear to injure the intestinal micro vascular bed unless NO synthase is concurrently inhibited. Such findings support the protective role of constitutively-formed NO, counteracting the injurious vascular actions of cytotoxic mediators released under pathological conditions.

Clinical healing of antimony-resistant cutaneous or mucocutaneous leishmaniasis following the combined administration of interferon-γ and pentavalent antimonial compounds

In an open trial, longer courses of pentavalent antimonials (Sb v) at sub-optimal doses (10 mg/kg body weight), in association with recombinant human interferon-γ (IFN-γ) (100 μg/m 2 of body surface area) were administered, by daily intramuscular injections, to 13 patients with diagnoses of cutaneous or mucocutaneous leishmaniasis unresponsive to Sb v. Four patients presented with large skin ulcers, and 9 had mucosal involvement as the main manifestation, the latter affecting the nose (3 cases), nose and septum (2 cases), nose and oral cavity (1 case), and nose, pharynx and larynx (3 cases). Except for one case with severe involvement of the upper respiratory tract, the lesions were fully resolved by the end of therapy (mean duration 40 ± 12 [ sd] d, range 30–60 d) in the 11 patients who completed therapy. The main side effects were headache and fever (7 cases), together with leucopenia and eosinophilia (4 cases). It is concluded that combined administration of low doses of Sb v plus IFN-γ may provide a novel therapeutic approach for the treatment of antimony-resistant cutaneous or mucocutaneous leishmaniasis. The possible mechanisms by which IFN-γ contributes to resolution of the disease are discussed.

1981 APhA Exposition and Annual Meeting Update

Coronary artery disease carries dual risk for atrial tachyarrhythmias and sudden cardiac death.To examine whether low-dose ranolazine and/or dronedarone can protect against vulnerability to atrial fibrillation (AF) and ventricular tachyarrhythmias.In chloralose-anesthetized, open-chest Yorkshire pigs (n = 15), the proximal segment of left circumflex (LCx) coronary artery was occluded to reduce flow by 75%. An electrode catheter was positioned on the left atrial appendage to measure AF threshold (AFT) before and during LCx coronary artery stenosis before and at 1 hour after dronedarone (0.5 mg/kg intravenous bolus over 5 minutes) and/or ranolazine administration (0.6 mg/kg intravenous bolus followed by 0.035 mg/kg/min).Before drug administration, LCx coronary artery stenosis lowered AFT from 25.2±1.7 mA control (mean±SEM) to 4.9±1.0 mA baseline (P<.01). At the low doses, neither ranolazine (plasma concentration 2.4±0.6 μM) nor dronedarone (plasma concentration 20.9±3.5 nM) alone blunted the ischemia-induced reduction in AFT but were effective together (from 25.2±1.7 mA control to 22.0±3.0 mA during stenosis; P = not significant). AF duration (P<.03) and AF inducibility (P = .012) were reduced by ranolazine and dronedarone together but not by either drug alone. Concurrently, combined but not separate administration blunted the ischemia-induced surge in T-wave heterogeneity, a marker of risk for ventricular tachyarrhythmias (from 43.1±11.1 μV control to 149.7±15.1 μV during stenosis, P<.001, compared to 61.7±13.7 μV control to 83.7±15.8 μV during stenosis, P = not significant).Combined administration of low doses of ranolazine and dronedarone exerts a potent antiarrhythmic action on ischemia-induced vulnerability to AF and ventricular tachyarrhythmias due to direct effects on myocardial electrical properties.

Alcohol and chlordiazepoxide increase suppressed aggression in mice.

The purpose of the present experiments was to investigate conditions under which alcohol and chlordiazepoxide (CDP) enhance aggression. Alcohol (300, 600, and 1200 mg/kg orally) and CDP (5, 10, and 20 mg/kg) failed to alter attack behavior in male mice confronting intruder mice in their home cages. When confrontations between attack-experienced mice and group-housed mice occurred in a neutral cage, attack and threat behavior was suppressed to about 50% of that in the resident's home cage. A low dose of alcohol (300 mg/kg) more than doubled the frequency of attacks and threats in the neutral cage. Higher doses of both drugs decreased attacks in the neutral cage. Combined administration of low doses of alcohol (150 and 300 mg/kg) and CDP (2.5 and 5.0 mg/kg) increased attack and threat frequency in the neutral cage to a larger extent than when either drug was given itself. The aggression-enhancing effects of alcohol and CDP in the neutral cage situation are consistent with the view that both drugs can lead to behavioral disinhibition. Alternatively, the results could reflect simply the ratedependency of alcohol effects on attack behavior, that is, low rates are increased whereas high rates remain unaffected. The present results also provide evidence for an additive interaction of both drugs in their depressant effects and, also, in their aggressionheightening effects.