Smoking or its cessation does not alter the susceptibility to in vitro LDL oxidation

BACKGROUND: Enhanced induction of low density lipoprotein (LDL) oxidation may play a role in the increased cardiovascular risk in smokers. We determined LDL oxidisability in vitro in non-smokers, smokers and in subjects after smoking cessation. PATIENTS AND METHODS: Plasma lipids and copper induced LDL oxidation in vitro were measured in 31 persistent smokers, 47 smokers who tried to stop smoking and 25 non-smokers. In the smoking cessation group, blood was collected before then 1, 3, 6 and 12 months after smoking cessation, and in the persistent smoking and non-smoking groups at baseline and after 12 months. Plasma thiobarbituric acid reactive substances (TBARS) were measured 3 times (at baseline then after 1 and 3 months) in all subjects who refrained from smoking (controlled by urinary cotinine concentrations) for at least 3 months. RESULTS: At baseline, no differences in mean age, body mass index and lipid profiles between groups were present. Seventeen subjects of the smoking cessation group (36%) managed to quit during 12 months. Smoking cessation was associated with an increase in mean weight (P 相似文献   

Amphotericin B lipid complex or amphotericin B multiple-dose administration to rabbits with elevated plasma cholesterol levels: pharmacokinetics in plasma and blood, plasma lipoprotein levels, distribution in tissues, and renal toxicities

The purpose of the present study was to determine if a relationship exists between the plasma cholesterol concentration, the severity of amphotericin B (AmpB)-induced renal toxicity, and the pharmacokinetics of AmpB in plasma in hypercholesterolemic rabbits administered multiple doses of amphotericin B (AmB) deoxycholate (Doc-AmB) and AmB lipid complex (ABLC). After 7 days of administration of a cholesterol-enriched diet (0.50% [wt/vol]) or a regular rabbit diet, each rabbit was administered a single intravenous bolus of Doc-AmB (n = 8) or ABLC (n = 10) (1.0 mg/kg of body weight) daily for 7 consecutive days (a total of eight doses). Blood samples were obtained daily before and 24 h after the administration of each dose and serially thereafter following the administration of the last dose for the assessment of pharmacokinetics in plasma, kidney toxicity, plasma lipoprotein levels, and drug distribution in tissue. The pharmacokinetics of AmB in blood following the administration of ABLC were also determined in rabbits fed cholesterol-enriched and regular diets (n = 3 each group). Before drug treatment, cholesterol-fed rabbits demonstrated marked increases in total, low-density lipoprotein (LDL), and triglyceride-rich lipoprotein (TRL) cholesterol levels in plasma compared with the levels in rabbits on a regular diet. No significant differences in total plasma triglyceride levels were observed. Significant increases in plasma creatinine levels were observed in rabbits fed a cholesterol-enriched diet (P < 0.05) and rabbits fed a regular diet (P < 0.05) when administered AmB. However, the magnitude of this increase was twofold greater in rabbits fed a regular diet than in rabbits fed a cholesterol-enriched diet. An increase in plasma creatinine levels was observed only in rabbits on a cholesterol-enriched diet administered ABLC. The pharmacokinetics of AmB were significantly altered in rabbits on a cholesterol-enriched diet administered Doc-AmB or ABLC compared to those in rabbits on a regular diet administered each of these compounds. The pharmacokinetics of AmB in blood were significantly different following ABLC administration but not following Doc-AmB administration in both rabbits fed cholesterol-enriched diets and rabbits fed regular diets compared to their corresponding pharmacokinetics in plasma. An increased percentage of AmB was recovered in the TRL fraction when Doc-AmB was administered to rabbits fed a cholesterol-enriched diet than when it was administered to rabbits fed a regular diet. Furthermore, an increased percentage of AmB was recovered in the LDL and TRL fractions when ABLC was administered to rabbits fed a cholesterol-enriched diet rabbits fed a regular diet. These findings suggest that an increase in plasma cholesterol levels modifies the pharmacokinetics of AmB and renal toxicity following the administration of multiple intravenous doses of Doc-AmB and ABLC.     

Endotoxin does not alter the pharmacokinetics of micafungin,but it impairs biliary excretion of micafungin via multidrug resistance-associated protein 2 (ABCC2/Mrp2) in rats

Micafungin, a newly developed echinocandin-type antifungal agent, is widely used for the treatment of deep-seated fungal infections including those of Candida species and Aspergillus species. In the present study, the possible alterations in the pharmacokinetics and biliary excretion of micafungin were investigated in endotoxemic rats induced by Klebsiella pneumoniae endotoxin. Endotoxin (2 mg/kg) was injected intraperitoneally 24 h before an intravenous injection of micafungin (1 mg/kg). No significant differences in the plasma concentration–time curves and pharmacokinetic parameters of micafungin were observed between endotoxin-treated and endotoxin-untreated rats. When endotoxin-treated rats received a constant-rate infusion of micafungin, the biliary clearance of micafungin was significantly decreased, whereas the steady-state plasma concentration did not change. By protein immunoblot analysis, a significant decrease in the expression of hepatic multidrug resistance-associated protein 2 (ABCC2/Mrp2), which is an efflux protein for micafungin, was observed in endotoxin-treated rats. These results suggest that endotoxin-induced decrease in the hepatobiliary excretion of micafungin is caused, at least in part, by the reduction of Mrp2-mediated hepatobiliary transport ability. The present study may provide information suggesting that micafungin can be used for patients with endotoxemia without the need for dosage adjustment.     

Nonlinear pharmacokinetics of (+/-)3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") and its major metabolites in squirrel monkeys at plasma concentrations of MDMA that develop after typical psychoactive doses

At certain doses, the psychoactive drug (+/-)3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") destroys brain serotonin axon terminals. By causing increases in plasma MDMA concentrations that exceed those predicted by the increase in dose, nonlinear pharmacokinetics has the potential to narrow the range between safe and neurotoxic doses of MDMA. The present study sought to determine whether the pharmacokinetics of MDMA in nonhuman primates are nonlinear and, if they are, to identify plasma concentrations of MDMA at which nonlinear accumulation of MDMA occurs. Four different oral doses of MDMA were tested in the same six squirrel monkeys in random order. At each dose, pharmacokinetic parameters for MDMA and its metabolites 3,4-dihydroxymethamphetamine (HHMA), 4-hydroxy-3-methoxymethamphetamine (HMMA), and 3,4-methylenedioxyamphetamine were determined. Doses were selected to be equivalent to 0.4, 0.8, 1.6, and 2.8 mg/kg doses in humans. The maximal concentration (C(max)) and area under the curve (AUC) of MDMA increased nonlinearly with dose, whereas the C(max) and AUC of the metabolites HHMA and HMMA remained relatively constant. Nonlinear MDMA pharmacokinetics occurred at plasma MDMA concentrations of 100 to 300 ng/ml and above. The half-life (T(1/2)) of MDMA and its metabolites also increased with dose. These results firmly establish nonlinear pharmacokinetics for MDMA in squirrel monkeys and indicate that nonlinear MDMA accumulation occurs at plasma MDMA concentrations that develop in humans taking typical doses. By raising MDMA concentrations and prolonging its action, nonlinear pharmacokinetics and T(1/2) prolongation, respectively, may influence the likelihood and severity of MDMA toxicities (including brain serotonin neurotoxicity).     

Infection with pinworms (Syphacia obvelata) does not affect the plasma corticosterone concentration in male, nonpregnant female, and pregnant female rats.

Pinworm infections are common in rodent colonies, but the effect of pinworms on the host hypothalamic-pituitary-adrenal (HPA) axis had not been investigated. Other parasites stimulate, inhibit, or have no effect on the HPA axis of their hosts. We studied the effect of Syphacia obvelata infection on plasma corticosterone concentrations in Sprague-Dawley rats. Blood samples were taken from male, female, and pregnant rats during an active infection, when all 21 rats examined harbored worms, and after 4 weeks of treatment with piperazine and ivermectin, when only 2 of the 23 rats examined harbored worms. Plasma corticosterone concentration was measured by radioimmunoassay, and all pinworms in the cecum and colon were counted. Plasma corticosterone concentration did not differ between infected and uninfected rats in any group of rats. Pinworms were much more abundant in pregnant rats than in male or nonpregnant female animals. Corticosterone was highest in pregnant females and lowest in males. In conclusion, infection with S. obvelata did not affect plasma corticosterone concentration in male, female, or pregnant rats, suggesting that such an infection does not invalidate studies of the HPA axis in these animals.     

严重多发伤患者血浆肠脂肪酸结合蛋白水平变化及其与胃肠功能障碍的关系

目的探讨严重多发伤患者血浆肠脂肪酸结合蛋白(iFABP)水平变化及其与创伤后胃肠功能障碍的关系。方法36例多发伤患者分为轻伤组(ISS评分<16分,15例)和重伤组(ISS评分>16分,21例),再根据是否并发胃肠功能障碍分为胃肠功能障碍组(32例)和非胃肠功能障碍组(4例),另10例择期手术者为正常对照组。正常对照组采外周静脉血1次,多发伤患者分别于伤后第1、3、5天采外周静脉血3次,采用酶联免疫吸附测试法检测iFABP。结果与正常对照组相比,轻伤组和重伤组血浆iFABP水平于伤后第1天即显著升高(P<0.01),且重伤组显著高于轻伤组(P<0.01),随后iFABP水平逐渐下降,轻伤组于第5天恢复至正常水平,而重伤组仍显著高于正常对照组(P<0.01);胃肠功能障碍组伤后第1天血浆iFABP水平显著高于非胃肠功能障碍组(P<0.01),其差异一直持续到创伤后第5天。多发伤后第1、3、5天血浆iFABP水平与胃肠功能障碍评分均有相关性。结论严重多发伤后早期血浆iFABP水平显著升高,其水平变化与创伤严重程度和胃肠功能障碍程度呈正相关,这种变化可能对创伤后胃肠功能障碍的早期预测有较重要意义。     

Subcellular post-transcriptional targeting: delivery of an intracellular protein to the extracellular leaflet of the plasma membrane using a glycosyl-phosphatidylinositol (GPI) membrane anchor in neurons and polarised epithelial cells

The effectiveness of viral vector-mediated gene transfer depends on the expression of therapeutic transgenes in the correct target cell types. So far, however, little attention has been given to targeted subcellular distribution of expressed transgenes. Targeting individual transgenes to particular subcellular compartments will provide various advantages in increasing the safety, efficacy, and specificity of viral vector-mediated gene delivery. Viruses normally hijack the cellular protein synthesis machinery for their own advantages. It is thus unknown whether cells infected with viral vectors will be able to target proteins to the correct subcellular organelles, or whether the subcellular targeting machinery would be selectively disrupted by viral infection. In this article we explored whether a herpes simplex virus type 1-derived vector could be used to deliver a transgene engineered to be targeted to the extracellular membrane of target cells. To do so we constructed a temperature-sensitive mutant HSV-1 vector, tsK-TT21 expressing a recombinant marker protein, tissue inhibitor of metalloproteinases (TIMP), linked to sequence encoding a signal for the addition of a glycosyl-phosphatidylinositol (GPI)-anchor within the endoplasmic reticulum. Our results demonstrate that HSV1-derived viral vectors can be used to target transgenes as GPI anchored proteins to the outside leaflet of plasma membranes, without disrupting the targeting machinery of host epithelial cells or neurons. This approach could then be used to target specific proteins to the cell membrane to modify cell-cell interactions, the function of specific plasma membrane proteins, or their interactions with other membrane proteins, and also to target a prodrug converting enzyme to the plasma membrane of target cells, therefore enhancing its cell killing effects.     

A highly conserved aspartic acid (Asp-155) anchors the terminal amine moiety of tryptamines and is involved in membrane targeting of the 5-HT(2A) serotonin receptor but does not participate in activation via a "salt-bridge disruption" mechanism

Discovering the molecular and atomic mechanism(s) by which G-protein-coupled receptors (GPCRs) are activated by agonists remains an elusive goal. Recently, studies examining two representative GPCRs (rhodopsin and alpha(1b)-adrenergic receptors) have suggested that the disruption of a putative "salt-bridge" between highly conserved residues in transmembrane (TM) helix III, involving aspartate or glutamate, and helix VII, involving a basic residue, results in receptor activation. We have tested whether this is a general mechanism for GPCR activation by constructing a model of the 5-hydroxytryptamine (5-HT)(2A) receptor and characterizing several mutations at the homologous residues (Asp-155 and Asn-363) of the 5-HT(2A) serotonin receptor. All of the mutants (D155A, D155N, D155E, D155Q, and S363A) resulted in receptors with reduced basal activity; in no case was evidence for constitutive activity revealed. Structure-function studies with tryptamine analogs and various Asp-155 mutants demonstrated that Asp-155 interacts with the terminal, and not indole, amine moiety of 5-HT(2A) agonists. Interestingly, the D155E mutation interfered with the membrane targeting of the 5-HT(2A) receptor, and an inverse relationship was discovered when comparing receptor activation and targeting for a series of Asp-155 mutants. This represents the first known instance in which a charged residue located in a putative TM helix alters the membrane targeting of a GPCR. Thus, for 5-HT(2A) receptors, the TMIII aspartic acid (Asp-155) is involved in anchoring the terminal amine moiety of indole agonists and in membrane targeting and not in receptor activation by salt-bridge disruption.     

Plasma levels, tissue distribution, and excretion of radioactivity after single-dose administration of (H)-oleic acid added to D-004, a lipid extract of the fruit of Roystonea regia, in rats

Background:

D-004, a lipid extract of the fruit of Roystonea regia, contains a mixture of fatty acids—mainly oleic, lauric, palmitic, and myristic acids, with oleic acid being among the most abundant—that has been found to reduce the risk for prostatic hyperplasia (PH) induced with testosterone (T) in rats. The pharmacokinetic profile of D-004 has not been reported.

Objective:

The objective of this study in rats was to assess plasma levels, tissue distribution, and excretion of total radioactivity (TR) after single-dose administration of oral D-004 radiolabeled with (³H)-oleic acid, as a surrogate for the pharmacokinetics of D-004.

Methods:

This experimental study was conducted at the Pharmacology Department, Center of Natural Products, National Center for Scientific Research, Havana, Cuba. Single doses of suspensions of (³H)-oleic acid 0.16 μCi/mg mixed with D-004 400 mg/kg (radioactive dose/animal 7.2 μCi) were given orally to male Wistar rats weighing 150 to 200 g assigned to the treated or control group. Three rats were euthanized at each of the following times: 0.25, 0.5, 1, 1.5, 2, 4, 8, 24, 48, 72, 96, and 144 hours after study drug administration. After administration, the rats euthanized at the last experimental time point were housed individually in metabolism cages. Urine and feces samples were collected daily. At each time point, blood samples were drawn and plasma samples were obtained using centrifugation. After euthanization, tissue samples (liver, lungs, spleen, brain, kidneys, adipose tissue, muscle, stomach, small and large intestines, adrenal glands, heart, testes, prostate, and seminal vesicles) were quickly removed, washed, blotted, and homogenized. Plasma (100 μL), tissue aliquots (100 mg), feces (10 mg), and urine (100μL) were dissolved and TR was measured. Samples were assayed in duplicate. Results were expressed in μgEq of radio-labeled oleic acid per milliliter of plasma or urine or gram of tissue or feces. Plasma, tissue, feces, and urine samples of rats that did not receive (³H)-oleic acid were used as controls. Excretion was expressed as the percentage of the radioactivity excreted via each route with respect to the total radioactive dose administered to each rat.

Results:

A total of 50 rats were included in the experiment (mean age, 4 weeks; mean weight, 310 g). Absorption was rapid; mean C_max was 195.56 (31.12) μgEq/mL, and mean T_max was 2 hours. Thereafter, a biphasic decay of TR was found: a rapid first phase (t_1/2α, 1.33 hours), followed by a slower second elimination phase (t_1/2β, 36.07 hours). Radioactivity was rapidly and broadly distributed throughout the tissues, with more accumulating in the prostate than elsewhere. In the first 8 hours, accumulation of TR was greatest in the prostate, followed by the liver, small intestine, and plasma. Subsequently, TR increased in the small intestine, while it decreased in the liver and plasma. In contrast, over the periods of 24 and 144 hours after administration, TR increased in the adipose tissue, while it decreased in the other tissues and plasma. During those intervals, TR was greatest in the prostate, followed by adipose tissue. Mean peak radioactivity in the prostate (562.41 μgEq/g) was reached at 4 hours and decreased slowly thereafter. The prostate had the highest values of t_1/2β and cumulative AUC compared with the other tissues and plasma. Mean (SD) TR was similar in feces (33.48% [4.90%]) and urine (28.96% [5.32%]), with total excretion being 62.40% (5.90%) of the administered dose.

Conclusions:

In this experimental study, after single-dose administration of oral D-004 radiolabeled with (³H)-oleic acid in rats, TR was rapidly and widely distributed across the tissues, with the prostate having the highest accumulation of radioactivity. Excretion of TR was limited, with similar amounts being excreted in feces and urine. The broad distribution of radiolabeled oleic acid and/or its metabolites suggests (SD) pharmacokinetic rationale for the effectiveness of D-004 in reducing the risk for PH induced with T in rats.     

The Src homology 2 domain of Vav is required for its compartmentation to the plasma membrane and activation of c-Jun NH(2)-terminal kinase 1

Vav is a hematopoietic cell-specific guanine nucleotide exchange factor (GEF) whose activation is mediated by receptor engagement. The relationship of Vav localization to its function is presently unclear. We found that Vav redistributes to the plasma membrane in response to Fcin receptor I (FcinRI) engagement. The redistribution of Vav was mediated by its Src homology 2 (SH2) domain and required Syk activity. The FcinRI and Vav were found to colocalize and were recruited to glycosphingolipid-enriched microdomains (GEMs). The scaffold protein, linker for activation of T cells (LAT), and Rac1 (a target of Vav activity) were constitutively present in GEMs. Expression of an SH2 domain-containing COOH-terminal fragment of Vav inhibited Vav phosphorylation and movement to the GEMs but had no effect on the tyrosine phosphorylation of the adaptor protein, SLP-76 (SH2 domain-containing leukocyte protein of 76 kD), and LAT. However, assembly of the multiprotein complex containing these proteins was inhibited. In addition, FcinRI-dependent activation of c-Jun NH(2)-terminal kinase 1 (JNK1) was also inhibited. Thus, Vav localization to the plasma membrane is mediated by its SH2 domain and may serve to regulate downstream effectors like JNK1.     

Blood-brain barrier (BBB) pharmacoproteomics: reconstruction of in vivo brain distribution of 11 P-glycoprotein substrates based on the BBB transporter protein concentration, in vitro intrinsic transport activity, and unbound fraction in plasma and brain in mice

The purpose of this study was to examine whether in vivo drug distribution to the brain can be reconstructed by integrating P-glycoprotein (P-gp)/mdr1a expression levels, P-gp in vitro activity, and drug unbound fractions in mouse plasma and brain. For 11 P-gp substrates, in vitro P-gp transport activities were determined by measuring transcellular transport across monolayers of mouse P-gp-transfected LLC-PK1 (L-mdr1a) and parental cells. P-gp expression amounts were determined by quantitative targeted absolute proteomics. Unbound drug fractions in plasma and brain were obtained from the literature and by measuring brain slice uptake, respectively. Brain-to-plasma concentration ratios (K(p brain)) and its ratios between wild-type and mdr1a/1b(-/-) mice (K(p brain) ratio) were obtained from the literature or determined by intravenous constant infusion. Unbound brain-to-plasma concentration ratios (K(p,uu,brain)) were estimated from K(p brain) and unbound fractions. Based on pharmacokinetic theory, K(p brain) ratios were reconstructed from in vitro P-gp transport activities and P-gp expression amounts in L-mdr1a cells and mouse brain capillaries. All reconstructed K(p brain) ratios were within a 1.6-fold range of observed values. K(p brain) then was reconstructed from the reconstructed K(p brain) ratios and unbound fractions. K(p,uu,brain) was reconstructed as the reciprocal of the reconstructed K(p brain) ratios. For quinidine, loperamide, risperidone, indinavir, dexamethasone, paclitaxel, verapamil, loratadine, and diazepam, the reconstructed K(p brain) and K(p,uu,brain) agreed with observed and estimated in vivo values within a 3-fold range, respectively. Thus, brain distributions of P-gp substrates can be reconstructed from P-gp expression levels, in vitro activity, and drug unbound fractions.