Cardiac function and remodeling is attenuated in transgenic rats expressing the human kallikrein-1 gene after myocardial infarction

Bradykinin coronary outflow, left ventricular performance and left ventricular dimensions of transgenic rats harboring the human tissue kallikrein-1 gene TGR(hKLK1) were investigated under basal and ischemic conditions.

Bradykinin content in the coronary outflow of buffer-perfused, isolated hearts of controls and TGR(hKLK1) was measured by specific radioimmunoassay before and after global ischemia. Left ventricular function and left ventricular dimensions were determined in vivo using a tip catheter and echocardiography 6 days and 3 weeks after induction of myocardial infarction. Left ventricular type I collagen mRNA expression was analyzed by RNase protection assay. Compared to controls, basal bradykinin outflow was 3.5 fold increased in TGR(hKLK1). Ischemia induced an increase of bradykinin coronary outflow in controls but did not induce a further increase in TGR(hKLK1). However, despite similar unchanged infarction sizes, left ventricular function and remodeling improved in TGR(hKLK1) after myocardial infarction, indicated by an increase in left ventricular pressure (+ 34%; P < 0.05), contractility (dp/dt max. + 25%; P < 0.05), and in ejection fraction (+ 20%; P < 0.05) as well as by a reduction in left ventricular enddiastolic pressure (− 49%, P < 0.05), left ventricular enddiastolic diameter (− 20%, P < 0.05), and collagen mRNA expression (− 15%, P < 0.05) compared to controls.

A chronically activated transgenic kallikrein kinin system with expression of human kallikrein-1 gene counteracts the progression of left ventricular contractile dysfunction after experimental myocardial infarction. Further studies have to show whether these results can be caused by other therapeutically options. Long acting bradykinin receptor agonists might be an alternative option to improve ischemic heart disease.     

Inhibition of P-type ATPases by [(dihydroindenyl)oxy]acetic acid (DIOA), a K+ -Cl- cotransporter inhibitor

[(Dihydroindenyl)oxy]acetic acid (DIOA) has been used as a potent inhibitor of K⁺–Cl⁻ cotransporter (IC₅₀ = 10 μM). Here we found that DIOA inhibited activities of P-type ATPases such as dog kidney Na⁺,K⁺-ATPase (IC₅₀ = 53 μM), hog gastric H⁺,K⁺-ATPase (IC₅₀ = 97 μM) and rabbit muscle Ca²⁺-ATPase (IC₅₀ = 127 μM). In the membrane preparation of the LLC-PK1 cells stably expressing rabbit gastric H⁺,K⁺-ATPase, DIOA inhibited activities of the endogenous Na⁺,K⁺-ATPase (IC₅₀ = 95 μM) and the exogenous H⁺,K⁺-ATPase (IC₅₀ = 75 μM). 5-Nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), a Cl⁻ channel blocker, had no effects on the DIOA-elicited inhibition of the P-type ATPases. These findings suggest that lower concentration of DIOA (< 20–30 μM) should be used for evaluation of the activity of K⁺–Cl⁻ cotransporter without affecting the activities of coexisting Na⁺,K⁺-ATPase and/or H⁺,K⁺-ATPase in cells.     

A new hydrogel for the extended and complete prednisolone release in the GI tract

The issue of incomplete release of poorly soluble drugs from sustained-release oral formulations is addressed using prednisolone (PDS) as the model drug and a novel highly swelling hydrogel as the rate-controlling material. The hydrogel was formed by heating N-carboxymethylchitosan (CMC) to 80 °C for 24 h. Swelling, alkalimetry, FTIR, DSC, and solid-state NMR studies showed that the treatment produced physical crosslinking, i.e., polymer chain entanglement. A controlled-release system was prepared by coating an inert compacted support of ethylcellulose (50 mg; diameter, 6 mm) with a CMC layer containing dispersed PDS powder (10–50 μm). The system was heated to crosslink the CMC coating, then drug release to simulated GI fluids was studied in vitro. The drug release pattern and term were modulated via the layer mass (LM) (10 or 14 mg cm⁻²) and/or the drug–polymer wt ratio (D/P) (1:5 or 2:5). The rate parameter, K, and the time exponent, n, of the Peppas equation were: K = 26.6 ± 0.3 h⁻ⁿ, n = 0.78 ± 0.02 (LM, 10 mg cm⁻²; D/P, 1:5); K = 24.7 ± 0.7 h⁻ⁿ, n = 0.56 ± 0.02 (LM, 14 mg cm⁻²; D/P, 1:5); K = 20.7 ± 0.3 h⁻ⁿ, n = 0.76 ± 0.01 (LM, 10 mg cm⁻²; D/P, 2:5). Hydrogel swelling was faster than drug release. This was controlled, in a first stage, by drug dissolution–diffusion in the swollen gel, and subsequently, by diffusion. The drug release rate was unaffected by the GI pH variations, and slightly affected by the environmental hydrodynamics. The system promises an extended and complete release of poorly soluble drugs in the GI tract.     

Alpha1L-adrenoceptors mediate contractions of the isolated mouse prostate

The subtype of ₁-adrenoceptor mediating noradrenaline-induced contractile responses in isolated mouse prostate glands was investigated. Adrenoceptor agonists were able to produce concentration-dependent contractions with the following rank order of potency: adrenaline ≥ noradrenaline ≥ clonidine = phenylephrine > dopamine ≥ isoprenaline. Concentration–response curves to noradrenaline of the prostatic smooth muscle were antagonised by prazosin, N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-, -dimethyl-1H-indole-3-ethanamine (RS-17053), 2-(2,6-dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane (WB 4101), tamsulosin and yohimbine with mean antagonist affinity estimates (pA₂ or apparent pK_B) of 8.12 ± 0.10, 6.56 ± 0.11, 8.38 ± 0.06, 10.14 ± 0.19 and 7.38 ± 1.36 respectively. Propranolol (1 μM) had no antagonist activity (P = 0.994, n = 6). Yohimbine (0.01, 0.1, 1 μM) had no antagonist activity in the presence of prazosin (0.1 μM) (P ≥ 0.059). The results obtained indicate that ₁-adrenoceptors mediate the contractile response in isolated preparations of the mouse prostate. Furthermore, the particular subtype of ₁-adrenoceptor mediating the response to exogenously administered noradrenaline corresponds to the _1L-subtype, the same subtype as that which has been shown to mediate noradrenaline-induced contractile activity in the human prostate.     

Microcalorimetric investigation of the toxic action of ammonium ferric(III) sulfate on the metabolic activity of pure microbes

A series of calorimetric experiments were performed to investigate toxic action of ammonium ferric sulfate (AFS) on Bacillus subtilis, Pseudomonas putida and Candida humicola. The power–time curves of micro-organism metabolism were obtained, and the action of them by addition of AFS was studied. C. humicola, B. subtilis and P. putida were inhibited completely when the concentrations were up to 320.0, 160.0 and 160.0 μg mL⁻¹, respectively. The relationships between growth rate constant (k) and doses of AFS were approximately linear for three microbes, P. putida for 10.0–160.0 μg mL⁻¹ (R = −0.9746), B. subtilis for 0–160.0 μg mL⁻¹ (R = −0.9868) and C. humicola for 10.0–320.0 μg mL⁻¹ (R = −0.9955). The total heat dissipated per milliliter (Q_T) for three microbes remained balance approximately during the lower doses, P. putida and B. subtilis less than the dose of 20.0 μg mL⁻¹, 0.56 ± 0.01 and 0.26 ± 0.01 J mL⁻¹, respectively, C. humicola less than the dose of 40.0 μg mL⁻¹, 0.58 ± 0.03 J mL⁻¹. The biomass and OD₆₀₀ of three micro-organisms growth in the absence of AFS also were obtained. The power–time curve of C. humicola growth coincided with its turbidity curve. It elucidates that microcalorimetric method agreed with the routine microbiology method.     

Role of tachykinin NK3 receptors in the release and effects of nerve growth factor in human isolated bronchi

The nerve growth factor (NGF) is a neurotrophic factor essential for the development and survival of neurons. It has also been identified as a mediator of inflammation and can cause airway hyperresponsiveness [Frossard et al., Eur. J. Pharmacol. 500, 453 (2004)]. Evidence in rodents suggests a link between tachykinins, the sensory nerves, and NGF. Recent evidence shows that NGF is released by the proinflammatory cytokine interleukin-1β and induces hyperresponsiveness to the tachykinin NK1 receptor agonist [Sar⁹,Met(O₂)¹¹]SP in isolated human bronchi. The aim of this study was to determine the role of sensory nerves through the effect of the tachykinin NK3 receptor antagonist SR142801 in the interleukin-1β effects and/or the NGF-induced airway hyperresponsiveness. SR142801 (0.1 μM) abolished the interleukin-1β (10 ng/ml, 21 °C, 15 h)-induced increased NGF release from isolated human bronchi in vitro (P < 0.05). In organ bath studies, SR142801 also abolished the interleukin-1β-induced airway hyperresponsiveness to [Sar⁹,Met(O₂)¹¹]SP (0.1 μM) (P < 0.05). SR142801 also inhibited the NGF-induced airway hyperresponsiveness (P < 0.01). This study suggests tachykininergic sensory nerves to be involved in the interleukin-1β-induced NGF release and airway hyperresponsiveness.     

Homocysteine levels in adolescent schizophrenia patients

Homocysteine is a sulfur containing amino acid that has been widely investigated for its putative role in cardiovascular and neuropsychiatric disorders. It has been suggested that homocysteine has implications especially in young, male schizophrenia patients. In this prospective case-control study, we compared plasma homocysteine levels in a group of adolescent schizophrenia inpatients (aged 14–21 years; n = 23) to normal healthy controls (n = 51). Mean plasma homocysteine levels were significantly higher in the patient group than in the control group (15.40 ± 2.00 and 9.78 ± 0.33 μmol/L, respectively, p < 0.032). The difference was almost entirely attributable to the male schizophrenia subgroup (18.18 ± 5.65 in male patients vs. 10.31 ± 5.33 μmol/L in female patients). The group × sex interaction was statistically significant (p = 0.0035). These data indicate that a subgroup of male adolescent schizophrenia patients has high homocysteine blood levels. The role of homocysteine in the pathophysiology of adolescent-onset schizophrenia merits further investigation.     

Oral bioavailability and intestinal secretion of amitriptyline: Role of P-glycoprotein?

The aim of the study was to evaluate the influence of quinidine, a P-glycoprotein inhibitor, on oral bioavailability and on intestinal secretion of amitriptyline, a tricyclic antidepressant. Amitriptyline was administrated intravenously (5 mg/kg) and orally (50 mg/kg) to rabbits, with and without quinidine. Jejunal segments of rats were mounted on diffusions chambers and the permeation of amitriptyline was measured across the tissue in luminal–serosal (LS) and serosal–luminal (SL) directions, with and without quinidine. Finally, an in situ recirculating intestinal perfusion model was performed in rabbits to study amitriptyline permeation in LS direction with and without quinidine. Absolute oral bioavailability (F) of amitriptyline was significantly increased more than three-fold in presence of quinidine (F = 0.6 ± 0.4% versus 1.9 ± 1.1%). The apparent permeability coefficients in SL direction were significantly higher than in LS direction (P_{app (SL)} = 6.01 ± 2.42 versus P_{app (LS)} = 4.90 ± 2.73 × 10⁻⁴ cm min⁻¹). In presence of quinidine, the intestinal absorption was increased (P_{app (LS)} = 4.02 ± 2.91 versus P_{app (LS)} = 5.99 ± 2.43 × 10⁻⁴ cm min⁻¹) and the intestinal secretion was decreased (P_{app (SL)} = 4.58 ± 0.54 versus P_{app (LS)} = 3.63 ± 1.46 × 10⁻⁴ cm min⁻¹) but not significantly. In conclusion, P-glycoprotein appears to be involved in oral amitriptyline absorption but other intestinal uptake and efflux transporters maybe implicated.     

alpha2B-adrenoceptor agonist ST-91 antagonizes beta2-adrenoceptor-mediated relaxation in rat mesenteric artery rings

We sought an isolated vascular preparation and experimental setting where the function of _2B-adrenoceptors could be demonstrated by non-recombinant technique. ST-91 (2-[2,6-diethylphenylamino]-2-imidazoline), an _2B-adrenoceptor agonist with a mixed adrenergic receptor type/subtype selection profile antagonized the relaxant effect of isoproterenol in endothelium-denuded rat mesenteric artery rings precontracted with phenylephrine. At 10^− 7 M of ST-91, the antagonism was characterized by a rightward shift of isoproterenol dose–response curve (A₅₀ = 6.81 ± 1.40 e− 7 (n = 4) vs the control 1.29 ± 0.25 e− 7 M (n = 4)) with no E_max depression. At 10^− 6 M the E_max depression was prevalent (36.1 ± 7.0% (n = 4) vs the control 79.9 ± 5.1% (n = 4)); both actions could be antagonized by the ₂-adrenoceptor antagonist yohimbine. The not subtype-selective ₂-adrenoceptor agonist xylazine (10^− 7 M) did not affect the relaxant action of isoproterenol. Present findings are discussed in the light of previously reported hemodynamic effects attributed to _2B-adrenoceptors in receptor subtype-knockout animals.     

5-Fluorotryptamine is a partial agonist at 5-HT3 receptors, and reveals that size and electronegativity at the 5 position of tryptamine are critical for efficient receptor function

Antagonists, but not agonists, of the 5-HT₃ receptor are useful therapeutic agents, and it is possible that partial agonists may also be potentially useful in the clinic. Here we show that 5-fluorotryptamine (5-FT) is a partial agonist at both 5-HT_3A and 5-HT_3AB receptors with an R_max (I_max / I_max5-HT) of 0.64 and 0.45 respectively. It is about 10 fold less potent than 5-HT: EC₅₀ = 16 and 27 μM, and K_i for displacement of [³H]granisetron binding = 0.8 and 1.8 μM for 5-HT_3A and 5-HT_3AB receptors respectively. We have also explored the potencies and efficacies of tryptamine and a range of 5-substituted tryptamine derivatives. At 5-HT_3A receptors tryptamine is a weak (R_max = 0.15), low affinity (EC₅₀ = 113 μM; K_i = 4.8 μM) partial agonist, while 5-chlorotryptamine has a similar affinity to 5-FT (EC_50 = 8.1 μM; K_i = 2.7 μM) but is a very weak partial agonist (R_max = 0. 0037). These, and data from 5-methyltryptamine and 5-methoxytryptamine, reveal the importance of size and electronegativity at this location for efficient channel opening.     

Differential expression of alpha1-adrenergic receptor subtypes in coronary microvascular endothelial cells in culture

Nicorandil has an anti-apoptotic effect on ischemic myocardium through the activation of ATP-sensitive potassium (K_ATP) channel. We tested the hypothesis that oral administration of nicorandil had a protective effect on ischemic skin flaps. A cranially based skin flap measuring 3 × 7 cm in full thickness was made on the back of rats. The rats were divided into a control group and 8 nicorandil groups (group 1–8) according to different doses and timings of administration. On day 7 at 5 cm, groups 1 to 6 (10 or 30 mg/kg twice per day for 3 days starting at 24 h before, 0.5 h before or 0.5 h after the operation) showed significantly higher blood perfusion change rate (73.3 ± 2.9%–79.1 ± 4.1% vs. 25.9 ± 8.6%, P < 0.01), and significantly higher survival rate (68.8 ± 4.8–75.2 ± 8.2% vs. 47.0 ± 2.8%, P < 0.05) than the control group. Many more surviving blood vessels were also observed in these groups. In contrast, no significant effects were found either in group 7 (30 mg/kg twice per day for 3 days starting 24 h after the operation) or group 8 (30 mg/kg once at 0.5 h after the operation). We did not find an angiogenic effect of nicorandil in vitro. Therefore, our results confirmed that the oral administration of nicorandil could protect tissues from necrosis in ischemic skin flaps. In addition, its protective effect depends on the time of first administration and the duration.     

Antithrombotic and hemostatic effects of a small molecule factor XIa inhibitor in rats

The effect of inhibiting activated blood coagulation factor XIa was determined in rat models of thrombosis and hemostasis. BMS-262084 is an irreversible and selective small molecule inhibitor of factor XIa with an IC₅₀ of 2.8 nM against human factor XIa. BMS-262084 doubled the activated thromboplastin time in human and rat plasma at 0.14 and 2.2 μM, respectively. Consistent with factor XIa inhibition, the prothrombin time was unaffected at up to 100 μM. BMS-262084 administered as an intravenous loading plus sustaining infusion was effective against FeCl₂-induced thrombosis in both the vena cava and carotid artery. Maximum thrombus weight reductions of 97 and 73%, respectively (P < 0.05), were achieved at a pretreatment dose of 12 mg/kg + 12 mg/kg/h which increased the ex vivo activated thromboplastin time to 3.0 times control. This dose level also arrested growth of venous and arterial thrombi when administered after partial thrombus formation. BMS-262084 was most potent in FeCl₂-induced venous thrombosis, decreasing thrombus weight 38% (P < 0.05) at a threshold dose of 0.2 mg/kg + 0.2 mg/kg/h. In contrast, doses of up to 24 mg/kg + 24 mg/kg/h had no effect on either tissue factor-induced venous thrombosis or the ex vivo prothrombin time. Doses of up to 24 mg/kg + 24 mg/kg/h also did not significantly prolong bleeding time provoked by either puncture of small mesenteric blood vessels, template incision of the renal cortex, or cuticle incision. These results demonstrate that pharmacologic inhibition of factor XIa achieves antithrombotic efficacy with minimal effects on provoked bleeding.     

Development and validation of a novel LC non-derivatization method for the determination of amikacin in pharmaceuticals based on evaporative light scattering detection

A novel method for the direct determination of the aminoglycoside antibiotic amikacin and its precursor component kanamycin was developed and validated, based on reversed phase LC with evaporative light scattering detector (ELSD). ELSD response to amikacin was found to be enhanced by: (a) use of ion-pairing acidic reagents of increased molecular mass, (b) increase of mobile phase volatility and (c) decrease of peak width and asymmetry (obtained by controlling the mobile phase acidity and/or ratio of organic solvent to water). Utilizing a Thermo Hypersil BetaBasic C₁₈ column, the selected optimized mobile phase was water–methanol (60:40, v/v), containing 3.0 ml l⁻¹ nonafluoropentanoic acid (18.2 mM) (isocratic elution with flow rate of 1.0 ml min⁻¹). ELSD experimental parameters were: nitrogen pressure 3.5 bar, evaporation temperature 50 °C, and gain 11. Amikacin was eluted at 8.6 min and kanamycin at 10.4 min with a resolution of 1.5. Logarithmic calibration curves were obtained from 7 to 77 μg ml⁻¹ (r > 0.9995) for amikacin and 8 to 105 μg ml⁻¹ (r > 0.998) for kanamycin, with a LOD equal to 2.2 and 2.5 μg ml⁻¹, respectively.

In amikacin sulfate pharmaceutical raw materials, the simultaneous determination of sulfate (t_R = 2.3 min, LOD = 1.8 μg ml⁻¹, range 5–40 μg ml⁻¹, %R.S.D. = 1.1, r > 0.9997), kanamycin and amikacin was feasible. No significant difference was found between the results of the developed LC–ELSD method and those of reference methods, while the mean recovery of kanamycin from spiked samples (0.5%, w/w) was 97.3% (%R.S.D. ≤ 2.0, n = 6). Further, the developed method was applied for the determination of amikacin in pharmaceutical formulations (injection solutions) without any interference from the matrix (recovery from spiked samples ranged from 95.6 to 103.8%).     

Validation of a reverse-phase high performance liquid chromatographic method for concurrent assay of a weak base (salmeterol xinafoate) and a pharmacologically active steroid (fluticasone propionate)

The analysis of weakly basic drugs such as salmeterol xinafoate (SX) by reverse-phase liquid chromatography remains a problem, particularly when present in combination with other drugs such as steroids and weak acids. This study describes the validation of an assay for a weakly basic drug, salmeterol (SB), its weakly acidic counter-ion, 1-hydroxy-2-naphthoic acid (XA), and the neutral glucocorticoid, fluticasone propionate (FP) using a second-generation silica stationary phase (Inertsil ODS-2). The assay utilized an Inertsil ODS-2 base-deactivated 250 mm × 4.6 mm, 5 μm HPLC column, with 75:25 methanol:0.6% aqueous ammonium acetate as the mobile phase. Under these near neutral conditions, SB demonstrated a good peak shape (tailing factor = 1.21 ± 0.02, n = 85). The method provided a short analysis time: XA, t_R = 2.96 min; SB, t_R = 5.23 min and FP, t_R = 7.01 min. The assay displayed good sensitivity for both XA (LOD for SX = 0.22 μg mL⁻¹) and SB (LOD for SX = 0.26 μg mL⁻¹). The limit of detection for FP was 0.19 μg mL⁻¹. Neither of the drugs was found to interfere in the determination of the other and the assay accuracy (% recovery) was high (the recoveries were: 99.58 ± 1.85% for XA, 99.49 ± 1.88% for SB and 100.24 ± 1.28% for FP). The assay reproducibility was determined with a mean coefficient of variance for the five calibration concentrations of XA = 0.71 ± 0.18%; SB = 1.11 ± 0.64% and FP = 0.92 ± 0.14%. Analysis of a pressurized metered dose inhaler formulation demonstrated recovery of the analytes that are within pharmacopoeial limits. It was shown that RP-HPLC was suitable for the high throughput analysis of the combination of SX and FP.     

mu-Opioid influence on transmesothelial resistance of isolated sheep pleura and parietal pericardium

The effect of morphine (μ-opioid receptor agonist) on the transmesothelial resistance (R_TM) of sheep's pleura and parietal pericardium was studied using the Ussing chamber technique. Basal transmesothelial resistance of parietal pleura was found to be 19.57 ± 0.32 Ω cm² and of visceral pleura was found to be 19.41 ± 0.31 Ω cm², whereas that of parietal pericardium was found to be 22.83 ± 0.4 Ω cm². Immediately after the addition of morphine (10^− 9 M) both apically and basolaterally on the parietal pleura and parietal pericardium, these values were significantly increased (P < 0.05). On the contrary, addition of morphine (10^− 9 M) resulted in a rapid increase, only when placed basolaterally on the visceral pleura (P < 0.05). In conclusion, our findings suggest that morphine, probably through μ-opioid stimulation, increases in vitro the transmesothelial resistance of the parietal pleura, of the visceral pleura when added basolaterally and of the parietal pericardium.     

Lyophilized Cheliensisin A submicron emulsion for intravenous injection: characterization, in vitro and in vivo antitumor effect

Growing attentions have been focused on natural antitumor drugs. Recently, a novel and potent antitumor drug Cheliensisin A (GC-51) with broad-spectrum efficiency has been developed. However, due to its poor water solubility and chemical instability, choosing the appropriate dosage form is of great significance. This study aimed at developing a lyophilized submicron emulsion for GC-51 and further improving the therapeutic index of the drug. The resultant lyophilized GC-51 submicron emulsion was much more stable than its solution, which can be stored for years without significant change on physicochemical properties. And its solubility was increased from 6.74 ± 0.14 to 2.00 ± 0.10 mg mL⁻¹. The 50% inhibitory concentration IC₅₀ values were calculated from growth curves by MTT assay on various tumor cell lines. Compared with the IC₅₀ of GC-51 crude drug, that of lyophilized GC-51 submicron emulsion decreased from 24.04 ± 1.97 to 8.23 ± 1.84 μg mL⁻¹ on HepG2, and from 31.08 ± 2.56 to 10.85 ± 2.09 μg mL⁻¹ on CT-26, from 17.90 ± 1.83 to 7.49 ± 1.87 μg mL⁻¹ on HeLa and from 16.38 ± 2.41 to 10.13 ± 2.12 μg mL⁻¹ on A549, respectively. In the time-dependent assay of tumor cell viability, lyophilized GC-51 submicron emulsion exhibited significantly lower inhibition rate in the initial action times, but increased gradually afterwards. That means lyophilized submicron emulsion as the vector for GC-51 had some protective and delayed release effect. Further, the in vivo therapeutic efficacy was measured in pulmonary metastasis of colon cancer-bearing BALB/c mice model. An obvious enhanced antitumor activity was observed after administration of lyophilized GC-51 submicron emulsion (P < 0.05), which increased from 22.78 ± 3.5 to 41.42 ± 4.2% compared with GC-51 injection. And the life span of tumor-bearing mice in lyophilized GC-51 submicron emulsion group was significantly longer than that of the mice in GC-51 injection and normal saline groups. Compared with crude drug, the lyophilized GC-51 submicron emulsion showed a significantly higher antitumor efficiency both in vivo and in vitro, suggesting a potential application in tumor chemotherapy.     

Effects of diazinon on acetylcholinesterase activity and lipid peroxidation in the brain of Oreochromis niloticus

The aim of this study was to investigate the effects of organophosphorus (OP) pesticide diazinon on acetylcholinesterase (AChE: EC 3.1.1.7) activity and its relationship to lipid peroxidation (LPO) in the brain of a freshwater fish, Oreochromis niloticus. Malondialdehyde (MDA) content was used as biomarker for LPO. Fish were exposed to 1 and 2 mg/L sublethal concentrations of diazinon for 1, 7, 15 and 30 days. In the entire experimental group, AChE activity in brain significantly decreased (up to 93% of control), whereas MDA content decreased after 1 day, and increased after 7 and 15 days of exposures. MDA was in similar level with the control group after diazinon exposure of 30 days. The findings of the present study show that diazinon inhibited AChE activity and it has LPO-inducing potential in fish. The inhibition of AChE activity in the brain of O. niloticus correlated with increased MDA levels after 7 and 15 days diazinon exposures (r = −0.661, P < 0.019; r = −0.652, P < 0.022, respectively).     

The serotonin reuptake inhibitor citalopram does not affect colonic sensitivity or compliance in rats

Altered serotonin signaling has been implicated in the pathophysiology of irritable bowel syndrome (IBS). Selective serotonin reuptake inhibitors (SSRI) improve IBS symptoms, although the mechanism of action remains unclear. We assessed the effects of the SSRI, citalopram, on colonic sensitivity and compliance in rats after acute and repeated administration. Colorectal distension was performed in conscious rats. Pressure–volume relationships during colorectal distension (2–20 mmHg), fitted using a power exponential model [Vol = V_max × exp[− (κ × RelP)^β], were used as a measure of colonic compliance. The visceral pain-related visceromotor response during colorectal distension (10–80 mmHg) was used to assess visceral sensitivity. Pressure–volume curves and visceromotor responses were assessed after acute citalopram (3 or 10 mg/kg, ip) or vehicle and after repeated treatment (7 and 14 days; 3 or 10 mg/kg/day). In vehicle-treated animals, pressure–volume curves were similar over time. Citalopram (acute or repeated treatment) did not affect neither the pressure–volume curves nor the visceromotor response to colorectal distension. Thus, citalopram, after acute or repeated administration, had no significant effects on colon compliance or visceral pain during colorectal distension in rats. These results agree with recent observations in humans suggesting that the therapeutic actions of citalopram in IBS are independent of any effects on colonic sensorimotor function.     

Enantioselective LC analysis of synephrine in natural products on a protein-based chiral stationary phase

An enantioselective LC method with photodiode array detection (PAD) was developed for the enantioseparation of (±)-synephrine from C. aurantium L. var. amara fruits and phytotherapic derivatives by using a protein-based chiral stationary phase with cellobiohydrolase as the chiral selector (Chiral-CBH). Analyses were carried out on a Chiral-CBH column (100 × 4.0 mm i.d., 5 μm), with a mobile phase consisting of 2-propanol (5%, w/w) in sodium phosphate buffer (pH 6.0; 10 mM) and disodium EDTA (50 μM). The flow rate was 0.8 mL/min. Detection was set at 225 nm. To identify the order of elution, the racemate was resolved by the preparation of suitable diastereoisomeric salts with antipodes of appropriate organic acids.

Isolation of synephrine from C. aurantium fruits and phytoproducts was performed by solid-phase extraction (SPE) with a strong cation-exchange phase.

The method developed was validated and was found to be linear in the 0.40–40.14 μg/mL range (r² = 1.000, P < 0.0001) for both synephrine enantiomers. The limit of detection (LOD) for each enantiomer was 0.04 μg/mL. The limit of quantification (LOQ) for each enantiomer was 0.13 μg/mL. Intra-day precision (calculated as %R.S.D.) ranged from 0.03 to 0.24% for (−)-synephrine and from 0.03 to 0.35% for (+)-synephrine. Inter-day precision (calculated as %R.S.D.) ranged from 0.07 to 1.45% for (−)-synephrine and from 0.06 to 1.26% for (+)-synephrine. Intra- and inter-day accuracies (calculated as %recovery) were in the ranges of 97.4–100.6 and 98.0–101.6% for (−)-synephrine, and in the ranges 97.0–101.5 and 98.1–102.8% for (+)-synephrine.

The results of the application of the method to the analysis of C. aurantium samples showed that (−)-synephrine was the main component. (+)-Synephrine was not detected in C. aurantium fruits and was present in low concentration in the phytoproducts.     

The effect of DHEA complementary treatment on heroin addicts participating in a rehabilitation program: A preliminary study

We evaluated the effect of DHEA complementary treatment in opiate addicts undergoing detoxification. DHEA (100 mg/day) or placebo was added to the routine medication protocol in a randomized, double blind controlled study. Follow-up for 12 months was conducted. Two separate DHEA-treated subgroups were identified by the Fuzzy clustering method: one showed statistically significant improvement in the severity of withdrawal symptoms, depression and anxiety scores (n = 34; p < 0.001 for all) and the other subgroup deteriorated in all measures (n = 15). DHEA at the end of the detoxification program showed a tendency towards correlation with the duration of abstinence (r = 0.6843; p > 0.05; n = 6), while a negative correlation was obtained with the cortisol level (r = − 0.900; p = 0.005, n = 8). The completion-rate of the DHEA-improved subgroup was greater than in the DHEA-deteriorated subgroup (64.7% vs. 33.3%, respectively).

The influence of supplementary DHEA treatment was mostly effective in heroin addicts who had not previously used either cocaine or benzodiazepines and who had experienced only few withdrawal programs.