Fabio Tabacco

Glycodermorphins: opioid peptides with potent and prolonged analgesic activity and enhanced blood-brain barrier penetration

1 In order to improve the in vivo stability of the opioid peptide dermorphin we synthesized O‐βglucosylated analogs ([Ser7‐O‐βGlc]dermorphin and [Ser7‐O‐βGlc(Ac)4]‐dermorphin) and C‐αgalactosylated analogs ([Ala7‐C‐αGal]dermorphin and [Ala7‐C‐αGal(Ac)4]‐dermorphin). 2 O‐ and C‐glycosylation of dermorphin halved the peptide affinity for brain μ‐opioid receptors and the biological potency in guinea‐pig ileum assay (GPI). Despite their lower opioid receptor affinity, when administered intracerebroventricularly (i.c.v., 8–40 pmol) and subcutaneously (s.c., 0.5–3 μmol kg−1) in rats, glycosylated analogs were two times more potent than dermorphin in reducing the nociceptive response to radiant heat. Acetylation of sugar hydroxyl groups reduces 5–10 times both biological activity on GPI and μ‐receptor affinity, whereas the antinociceptive potency was equal to (i.c.v.) or only two‐three times lower (s.c.) than dermorphin potency. 3 Blood‐Brain Barrier Permeability Index (BBB‐PI) of the glycodermorphins was significantly higher than that of dermorphin, indicating a facilitated entry into the brain: O‐β‐linked glucoconiugates are expected to enter CNS by the glucose transporter GLUT‐1 of the endothelial barrier. However the calculated BBB‐PI for the C‐αgalactoside was about two times higher than that of the O‐βglucoside, excluding the implication of GLUT‐1 that is known to be selective for O‐β‐links and preferring for the exose glucose. 4 The enhanced brain permeability with the subsequent decrease in peripheral dosage of these opioid peptides did not result in lowering constipation.

Inflammation and immune response in acute aortic dissection.

Abstract Objective. The aim of our study was to evaluate the lymphocyte subpopulations and the cytokines in the peripheral blood of patients with type-A Stanford acute aortic dissection (AAD group) and to determine whether inflammatory cells are present at the site of aortic dissection. Methods. Thirty-five consecutive patients with type-A Stanford dissection were evaluated for haemochrome and lymphocyte subpopulations (CD3+, CD4+, CD8+, CD19+, CD4+CD25+, CD16+CD56+, CD4+CD28−, CD8+CD28−) by flow cytometry. C-reactive protein (CRP), tumour necrosis factor (TNF)-α, interleukin (IL)-2, IL-4, IL-6, IL-8, IL-10, interferon-gamma (IFN-γ), and monocyte chemoattractant protein (MCP)-1 were measured by ELISA. In addition, immunohistochemical staining with cell type-specific antibodies was performed to study the inflammatory cells detected inside the aortic wall. Results. In the AAD group, a significant increase in natural killer (NK) (P = 0.032), B cells (P = 0.022), and CD8+CD28− (P = 0.045) subpopulations was observed, whereas there was a significant decrease in total T lymphocytes (P = 0.004) and T helper fractions (P = 0.005). Moreover, a significant increase in CRP (P < 0.0001), IL-6 (P < 0.0001), IL-8 (P < 0.0001), IL-10 (P < 0.0001), TNF-α (P < 0.0001), and MCP-1 (P < 0.001) was observed; macrophages represented the main population detected inside the media. Conclusions. Our results strongly support the hypothesis of a pivotal role of innate immunity in type-A Stanford AAD.

Brain Natriuretic Peptide and N-Terminal Pro-B-Type Natriuretic Peptide Show a Different Profile in Response to Acute Decompensated Heart Failure Treatment

Brain natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are currently used for the diagnosis, prognosis, and therapeutic decision making in heart failure patients. The aim of the study was to compare BNP and NT-proBNP plasma concentration profiles in 42 patients with decompensated heart failure who underwent treatment in the emergency department. A significant decrease in both peptide concentrations fell beyond 24 hours of therapy. BNP concentration underwent a more responsive change from admission (-54.1%+/-8.6% at 72 hours and -57.4%+/-7.6% at discharge) than NT-proBNP concentration (-17.6%+/-5.4% at 72 hours and -18.6%+/-5.6% at discharge). Although BNP and NT-proBNP concentrations were highly correlated, no correlation in their variations was found, a finding that suggests a different kinetic behavior in response to treatment. Sequential measurements of BNP and NT-proBNP provide a reliable marker to confirm clinical improvement after 24 hours of treatment. BNP may show some advantages over NT-proBNP as a more sensitive marker of early stabilization in response to therapy.

Respiratory and cardiovascular effects of the μ‐opioid receptor agonist [Lys7]dermorphin in awake rats

Changes in respiratory variables, arterial blood pressure and heart rate were studied in awake rats after injection of the opioid peptide [Lys7]dermorphin and its main metabolites, [1‐5]dermorphin and [1‐4]dermorphin. Fifteen minutes after injection, doses of [Lys7]dermorphin producing antinociception (i.c.v., 36–120 nmol; s.c., 0.12–4.7 μmol kg−1) significantly increased respiratory frequency and minute volume of rats breathing air or hypoxic inspirates. This respiratory stimulation was reversed to depression by the 5‐HT receptor antagonist ritanserin (2 mg kg−1, s.c.), was blocked by naloxone (0.1 mg kg−1, s.c.), significantly reduced by the μ1 opioid receptor antagonist naloxonazine (10 mg kg−1, s.c., 24 h before) but unaffected by peripherally acting opioid antagonist naloxone methyl bromide (3 mg kg−1, s.c.). Forty five minutes after injection, doses of the peptide producing catalepsy (s.c., 8.3–14.2 μmol kg−1, i.c.v., 360 nmol) significantly reduced respiratory frequency and volume of rats breathing air and blocked the hypercapnic ventilator response of rats breathing from 4% to 10% CO2. I.c.v. administration of [1‐5]dermorphin and [1‐4]dermorphin (from 36 to 360 nmol) never stimulated respiration but significantly reduced basal and CO2‐stimulated ventilation. Opioid respiratory depression was only antagonized by naloxone. In awake rats, [Lys7]dermorphin (0.1–1 mg kg−1, s.c.) decreased blood pressure. This hypotensive response was abolished by naloxone, reduced by naloxone methyl bromide and unaffected by naloxonazine. In conclusion, the present study indicates that analgesic doses of [Lys7]dermorphin stimulate respiration by activating central μ1 opioid receptors and this respiratory stimulation involves a forebrain 5‐hydroxytryptaminergic excitatory pathway.

Immunological characterization of the allergic contact mucositis related to the ingestion of nickel-rich foods

BACKGROUND The ingestion of nickel (Ni)-rich foods may result in allergic contact mucositis (ACM), a not yet well defined condition identifiable by oral mucosa patch test (omPT). Our aim was to characterize immunologically the ACM taking advantage from the allergen exposure that occurs during the omPT for Ni. METHODS Thirty-seven symptomatic patients underwent to omPT for Ni. Before and after omPT, serum and urine Ni concentrations were determined by mass spectrometry, the white blood cells were counted by hemochromocytometric assay, the peripheral lymphocyte typing was carried out by flow cytometry, total IgE and cytokine serum concentrations were measured by immunoenzymatic assays. The local lymphocyte typing was performed by immunohistochemistry only after omPT. RESULTS According to the omPT outcomes, 25 patients were defined as Ni-sensitive and the remaining 12 as controls. After omPT, serum and urine Ni concentrations increased significantly in all patients, while a significant increment of circulating lymphocytes and neutrophils was highlighted, respectively, in Ni-sensitive and control patients. Consistently, the Th and Tc circulating lymphocytes, as well as the Th/Tc ratio increased significantly in Ni-sensitive patients after omPT. No noteworthy increment in serum concentrations of total IgE and selected cytokines was observed in any patient after omPT. The presence of CD3+, CD4+, and CD8+ cells was highlighted on the oral mucosa biopsy samples taken from Ni-sensitive patients after omPT. CONCLUSIONS In patients with ACM, a local adaptive response with increased lymphocyte trafficking appears to be the most likely mechanism of reaction to Ni administered with the omPT.

Enhancing treatment of obesity by using a distracting mini-meal: a new approach to an old problem

OBJECTIVEThe management of obesity, apart from exercise, mainly involves a calorie restriction regimen. A pharmaceutical treatment is often used to improve patient compliance and diet effectiveness, although several side-effects have previously been described. To improve patient compliance and diet effectiveness without incurring unpleasant side-effects, we evaluated whether a distracting mini-meal can physiologically decrease the absorption of fats and carbohydrates.DESIGNTwo minutes before each of the three meals consumed daily, 32 obese patients were treated with a distracting mini-meal, 32 with metformin, and 32 with placebo. At baseline and after 1, 3, and 6 months of treatment, body weight, body mass index, waist circumference, fasting/post-prandial insulinaemia and glycaemia, homeostasis model assessment-index, triacylglycerols, and total cholesterol were evaluated.RESULTSAll patients showed good compliance. With the exception of post-prandial glycaemia, a significant reduction in all parameters was documented in every group, albeit the greater variation was observed in patients treated with a distracting mini-meal or metformin. No one showed noteworthy side-effects.CONCLUSIONSOur study focuses on a distracting mini-meal that could become a useful tool in enhancing weight loss. The beneficial effect of a distracting meal on insulin resistance, glucose, and lipid metabolism suggest its possible use to prevent or mitigate obesity-related disorders.