Health Effects of Subchronic Exposure to Diesel–Water Emulsion Emission

The U.S. Environmental Protection Agency (EPA) National Ambient Air Quality Standards for ozone and particulate matter are requiring urban nonattainment areas to implement pollution-reduction strategies for anthropogenic source emissions. A type of fuel shown to decrease combustion emissions components versus traditional diesel fuels is the diesel–water emulsion. The Lubrizol Corporation in conjunction with Lovelace Respiratory Research Institute and several subcontracting laboratories recently conducted a rodent health assessment of inhaled combustion emissions of PuriNO_x diesel fuel emulsion. Combustion emissions from either of two 2001 model Cummins 5.9-L ISB engines were diluted with charcoal-filtered air to exposure concentrations of 100, 200, and 400 μ g total particulate matter/m³. The engines were operated on a continuously repeating, heavy-duty certification cycle (U.S. Code of Federal Regulations, Title 40, Chapter I) using Rotella-T 15W-40 engine oil. Nitrogen oxide and particulate matter were reduced when engines were operated on PuriNO_x versus California Air Resources Board diesel fuel under these conditions. Male and female F344 rats were housed in Hazleton H2000 exposure chambers and exposed to exhaust atmospheres 6 h/day, 5 days/wk for the first 11 wk and 7 days/wk threafter. Exposures ranged from 58 to 70 days, depending on the treatment group. Indicators of general toxicity (body weight, organ weight, clinical pathology, and histopathology), neurotoxicity (glial fibrillary acidic protein assay), genotoxicity (Ames assay, micronucleus, sister chromatid exchange), and reproduction and development were measured. Overall, effects observed were mild. Emulsion combustion emissions were not associated with neurotoxicity, reproductive/developmental toxicity, or in vivo genotoxicity. Small decreases in serum cholesterol and small increases in platelet values in some groups of exposed animals were observed. Particulate matter accumulation within alveolar macrophages was evident in all exposure groups. These findings are consistent with normal physiological responses to particle inhalation. Other statistically significant effects were present in some measured parameters of other exposed groups but were not clearly attributed to emissions exposure. Positive mutagenic responses in several strains of Salmonella typhimurium were observed subsequent to treatment with emulsion emissions subfractions. Based on the cholesterol and platelet results, it can be concluded that the 100-μ g/m³ exposure level was the no-observed-effect level. In general, biological findings in diesel emulsion emission-exposed animals and bacteria were consistent with exposure to petroleum diesel exhaust in the F344 rat and Ames assays.     

Effects of 7,8-dihydroxyflavone on rat jejunal dynamics subjected to ischaemia–reperfusion injury

It is known that 7,8-dihydroxyflavone (7,8-DHF), a synthetic agonist specific for TrkB, promotes intestinal cholinergic contraction. However, after intestinal ischaemia–reperfusion (IR) injury, how 7,8-DHF affects intestinal contractile dynamics is unknown. In this study, an IR injury model was prepared with rats subjected to 45 minutes clamping of the superior mesenteric artery. The IR injury decreased postoperative food intake and body weight, delayed defecation time, lowered intestinal propulsive rate and decreased cholinergic contraction of jejunal muscle strips, indicating the occurrence of injured jejunal contraction after IR. Feeding rats with 7,8-DHF improved these intestinal activities injured by IR, which exhibited the in vivo effect of 7,8-DHF. To explore its molecular mechanism, the expression and phosphorylation of TrkB, PLC γ1, Akt, and ERK1/2 in the jejunal strips were examined with western blots. The IR injury significantly decreased the expression and phosphorylation levels of all factors studied here. However, 7,8-DHF feeding specifically enhanced the phosphorylation of TrkB, PLC γ1 and Akt factors in both sham- and IR-operated rats, indicating that 7,8-DHF may have activated TrkB which then activated its downstream PLC γ1 and Akt. Finally, we found that 7,8-DHF augmented cholinergic receptor M3 expression somehow. These results imply a possibility that 7,8-DHF might be capable of alleviating the jejunal contractile damage caused by IR through activation of TrkB and augmentation of M3 expression.     

Biological Tools to Study the Effects of Environmental Contaminants at the Feto–Maternal Interface

The identification of reproductive toxicants is a major scientific challenge for human health. Prenatal life is the most vulnerable and important time span of human development. For obvious ethical reasons, in vivo models cannot be used in human pregnancy, and animal models do not perfectly reflect human physiology. This review describes the in vitro test models representative of the human feto–maternal interface and the effects of environmental chemicals with estrogen-like activity, mainly bisphenol A and para-nonylphenol, with a particular emphasis on the effects at low, nontoxic doses similar to concentrations commonly detected in the population.     

Antinociceptive activity and chemical composition of Wei–Chang–An–Wan extracts

Abstract

Context: Currently, famous traditional Chinese medicine formulas have undergone re-evaluation and development in China. Wei–Chang–An–Wan (WCAW) as one of them has been used for treating various gastrointestinal diseases for several decades. The secondary development of WCAW is in progress so as to interpret the effective material basis or find new pharmacological activity.

Objective: To evaluate the antinociceptive effect of methanol extract of WCAW (ME) as well as four fractions (P.E., EtOAc, n-BuOH, H₂O) and obtain information on the correlation between the contents of the fractions and antinociceptive effect.

Materials and methods: ME was divided into four parts extracted by petroleum ether, ethyl acetate and n-butanol. Antinociceptive activity was evaluated by three models of acetic acid–induced writhing, formalin and hot-plate test in mice after repetitive administration of ME at 200, 400 or 800?mg/kg, P.E. 132?mg/kg, EtOAc 106?mg/kg, n-BuOH 176?mg/kg and H₂O 176?mg/kg for six days. The chemical compounds were analyzed by HPLC-ESI-MS.

Results: ME at 800?mg/kg inhibited acid-induced writhing by 84.69%, and reduced the licking time of second phase in formalin test by 53.23%. The inhibition rates in acid-induced writhing of P.E., EtOAc, n-BuOH and H₂O were 27.79, 33.85, 38.97 and 37.69%, respectively, and in formalin test about 50%. They had no effect on the hot-plate test. HPLC-ESI-MS analysis showed that 68 chemical compounds were detected and 41 compounds were identified from ME.

Discussion and conclusion: The results obtained herein indicate that WCAW possesses the antinociceptive activity that provides a new aspect in clinical application.     

An Overview of the Treatment of Less Common Non–Lactose-Fermenting Gram-Negative Bacteria

Stenotrophomonas maltophilia, Burkholderia cepacia complex, Elizabethkingia spp., Chryseobacterium spp., Achromobacter spp., and Alcaligenes spp. are less-common non–lactose-fermenting bacteria that have emerged as important opportunistic pathogens. Patients at the highest risk for these infections include the immunocompromised, those with cystic fibrosis, and the critically ill. These opportunistic pathogens are frequently drug resistant through the expression of β-lactamases, multidrug efflux pumps, aminoglycoside-modifying enzymes, and target site alterations discussed in detail throughout this review. As a result, treatment is extremely challenging. For each pathogen, this review will examine the epidemiology, mechanisms of resistance, and in vitro and in vivo data including that for novel β-lactam/β-lactamase inhibitors and cefiderocol. Treatment recommendations are provided based on the available literature.     

Effects of prednisolone on behavior and hypothalamic–pituitary–interrenal axis activity in zebrafish

Prednisolone is a synthetic glucocorticoid used clinically for treating allergies, inflammation, and autoimmune diseases. Long-term prednisolone use has been shown to have negative effects on physiology and mood. We aimed to study the pharmacology and toxicology of glucocorticoid-like drugs by investigating behavioral and hypothalamic–pituitary–interrenal (HPI) axis effects in a zebrafish model. Zebrafish embryos 24 h post fertilization were exposed to 25 μM prednisolone. Their behavior was investigated 5 days post fertilization (dpf), and their HPI axis-related activity and related neurotransmitter levels were investigated 3, 4, 5, and 6 dpf. The behavior results showed that exposure to prednisolone resulted in decreased autonomic activity and low sensitivity to light. qRT-PCR and ELISA results showed decreased activity of the HPI axis and increased secretion of dopamine and serotonin after exposure to prednisolone. This study provides us with new insights into understanding the effects of glucocorticoids on the HPI axis.     

Distribution of microcystin-LR to testis of male Sprague–Dawley rats

Microcystins (MCs) are a group of cyclic heptapeptide toxins produced by naturally freshwater cyanobacteria. Among more than 90 identified analogues of microcystins, microcystin-LR (MC-LR) is the most abundant and toxic. Our previous investigations indicated that MC-LR displays male reproductive toxicity, but the target of MC-LR in testes remains unclear. To this end, the present study is designed to elucidate whether microcystin-LR could be distributed to testes and explore the target cells in testes. In the in vivo study, male Sprague–Dawley rats were injected intraperitoneally with MC-LR at a dose of 300 μg/kg per day for 6 days. MC-LR was detected in testes, mainly within seminiferous tubules, which was further validated by Western blot. The concentrations of MC-LR were determined by LC–MS analysis, with a result of 0.0252 ± 0.0037 and 0.0056 ± 0.0012 μg/g dry weight in liver and testis respectively. In the in vitro study, Primary cultured spermatogonia, Sertoli cells and Leydig cells were exposed to MC-LR respectively, and MC-LR was observed to enter spermatogonia and Sertoli cells, but not Leydig cells. These results suggested that the reproductive toxicity of MC-LR were induced by its distribution in testis. Spermatogonia and Sertoli cells are important target cells.     

Aerosolized Montelukast Polymeric Particles—An Alternative to Oral Montelukast–Alleviate Symptoms of Asthma in a Rodent Model

Purpose

Cysteinyl leukotrienes (CysLTs) propagate inflammatory reactions that result from allergen exposure in asthma. Montelukast, a CysLT type-1 receptor antagonist, disrupts mediator–receptor interactions and minimizes inflammatory response. In this study, we have evaluated anti-asthmatic efficacy of inhalable montelukast-loaded large porous particulate formulations in ovalbumin-induced rat airway inflammation model that mimics asthma.

Methods

The anti-inflammatory effects of a montelukast-loaded formulation were investigated in rats by measuring the total protein content, levels of injury markers and number of inflammatory cells in the bronchoalveolar lavage fluid (BALF). The histopathological studies assessed the morphological and structural changes that occur in asthmatic lungs. Animals were also challenged with methacholine to examine the airway hyper-reactivity.

Results

Compared with healthy animals, asthmatic animals showed a 3.8- and 4.77-fold increase in the protein content and number of inflammatory cells in BALF, respectively. Intratracheal montelukast particles reduced the protein content by 3.3-fold and the number of inflammatory cells by 2.62-fold. Also, montelukast particles reduced the lactate dehydrogenase (LDH) and myeloperoxidase (MPO) levels by a 4.87- and 6.8-fold in BALF, respectively. Montelukast particles reduced the airway wall thickness by 2.5-fold compared with untreated asthmatic lungs. Further, particulate formulation protected the lungs against methacholine-induced bronchial provocation (p?Conclusions Respirable large porous particles containing montelukast alleviated allergen-induced inflammatory response in an animal model and prevented histological changes associated with asthma. Thus montelukast-loaded large porous polylactic acid (PLA) particles could be an aerosolized delivery approach for administration of currently available oral montelukast.     

Effects of cysteine on the pharmacokinetics of docetaxel in rats with protein–calorie malnutrition

1. The objective of this study is to report the effects of cysteine on the pharmacokinetics of intravenous and oral docetaxel in rats with protein–calorie malnutrition (PCM). The in vivo pharmacokinetics and in vitro hepatic/intestinal metabolism of docetaxel were assessed using control, CC (control with cysteine), PCM and PCMC (PCM with cysteine) rats. The effects of cysteine on the intestinal absorption of docetaxel were further investigated through in vitro transport studies using rat intestine and Caco-2 cell monolayers.

2. The AUCs (the areas under the plasma concentration-time curve from time zero to time infinity) of intravenous docetaxel in PCM rats were significantly greater than in the control rats because of the significant decrease in the hepatic CYP3A. In PCMC rats, the elevated AUCs in PCM rats returned to control levels. The AUC_{0–6 h}s of oral docetaxel in PCM rats were significantly smaller than that in the control rats, mainly due to the decrease in gastrointestinal absorption. In CC and PCMC rats, oral cysteine supplement enhanced the gastrointestinal absorption of docetaxel probably via intestinal P-gp inhibition.

3. If the present rat data could be expressed to humans, the alterations in docetaxel absorption and metabolism should be considered in designing a dosage regimen for cancer patients with PCM state after cysteine supplement.

     

Effects of mycophenolic acid–glucosamine conjugates on the base of kidney targeted drug delivery

Mycophenolic acid has played an important role in treating immunosuppression and autoimmune diseases. Nevertheless, the agent needs a high dosage in treatment, following some side effects. To tackle this problem, in this study, mycophenolic acid–glucosamine conjugate (MGC), modified by 2-glucosamine, was synthesized to achieve kidney targeting and improved drug efficacy with a lower dosage. ¹H NMR, ¹³C NMR and HRMS spectroscopy were used to verify the conjugate whose stability was good in vitro. The transport of MGC by human proximal renal tubular epithelial HK-2 cells was temperature-, time-, concentration-dependent and saturable, suggesting the involvement of carrier-mediated uptake. In addition, the cellular uptake of MGC dropped substantially with the inhibition of megalin receptor. The specific tissue distribution indicated the commendable renal-targeting capability of MGC. The concentration of MGC was improved in the kidney except for other tissues, about 6.76 times higher than that of MPA. Further, the bioavailability of MGC in plasma decreased as compared with mycophenolic acid. Moreover, therapeutic effect of MGC was enhanced significantly compared with MPA in the acute kidney injury model. All the findings suggested the potential of mycophenolic acid–glucosamine conjugate in kidney targeted drug delivery.     

Michaelis–Menten kinetic analysis of drugs of abuse to estimate their affinity to human P-glycoprotein

The pharmacokinetics of various important drugs are known to be significantly influenced by the human ABC transporter P-glycoprotein (P-gp), which may lead to clinically relevant drug–drug interactions. In contrast to therapeutic drugs, emerging drugs of abuse (DOA) are sold and consumed without any safety pharmacology testing. Only some studies on their metabolism were published, but none about their affinity to the transporter systems. Therefore, 47 DOAs from various classes were tested for their P-gp affinity using human P-gp (hP-gp) to predict possible drug–drug interactions. DOAs were initially screened for general hP-gp affinity and further characterized by modeling classic Michaelis–Menten kinetics and assessing their K_m and V_max values. Among the tested drugs, 12 showed a stimulation of ATPase activity. The most intensive stimulating DOAs were further investigated and compared with the known P-gp model substrates sertraline and verapamil. ATPase stimulation kinetics could be modeled for the entactogen 3,4-methylenedioxy-α-ethylphenethylamine (3,4-BDB), the hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI), the abused alkaloid glaucine, the opioid-like drugs N-iso-propyl-1,2-diphenylethylamine (NPDPA), and N-(1-phenylcyclohexyl)-3-ethoxypropanamine (PCEPA), with K_m and V_max values within the same range as for verapamil or sertraline. As a consequence interactions with other drugs being P-gp substrates might be considered to be very likely and further studies should be encouraged.     

The Effects of Unsaturated Factors on Ring C to Chemical Propertiesof Podophyllotoxin Analogues

Podophyllotoxone, 4β-hydroxy-2,3-en-apopicropodophyllin, and 4-deoxy-4β-azado-2,3-en-apo-picropodophyUin can easily transform to 4-hydroxy-dehydropicropodophyUin, dehydroanhydropicropodophllyin and4-amino-dehydropicropodophyllin respectively in different conditions. These properties remind .us to be careful inhandling related compounds in similar conditions.     

Predicting Pharmacokinetics of Drugs Using Physiologically Based Modeling—Application to Food Effects

Our knowledge of the major mechanisms underlying the effect of food on drug absorption allows reliable qualitative prediction based on biopharmaceutical properties, which can be assessed during the pre-clinical phase of drug discovery. Furthermore, several recent examples have shown that physiologically based absorption models incorporating biorelevant drug solubility measurements can provide quite accurate quantitative prediction of food effect. However, many molecules currently in development have distinctly sub-optimal biopharmaceutical properties, making the quantitative prediction of food effect for different formulations from in vitro data very challenging. If such drugs reach clinical development and show undesirable variability when dosed with food, improved formulation can help to reduce the food effect and carefully designed in vivo studies in dogs can be a useful guide to clinical formulation development. Even so, such in vivo studies provide limited throughput for screening, and food effects seen in dog cannot always be directly translated to human. This paper describes how physiologically based absorption modeling can play a role in the prediction of food effect by integrating the data generated during pre-clinical and clinical research and development. Such data include physicochemical and in vitro drug properties, biorelevant solubility and dissolution, and in vivo pre-clinical and clinical pharmacokinetic data. Some background to current physiological absorption models of human and dog is given, and refinements to models of in vivo drug solubility and dissolution are described. These are illustrated with examples using GastroPlus? to simulate the food effect in dog and human for different formulations of two marketed drugs.     

Effects of Δ9-tetrahydrocannabinol in individuals with a familial vulnerability to alcoholism

Background and aims

A family history (FH) of alcoholism accounts for approximately 50 % of the risk of developing alcohol problems. Several lines of preclinical evidence suggest that brain cannabinoid receptor (CB₁R) function may mediate the effects of alcohol and risk for developing alcoholism including the observations that reduced CB₁R function decreases alcohol-related behaviors and enhanced CB₁R function increases them. In this first human study, we probed CB₁R function in individuals vulnerable to alcoholism with the exogenous cannabinoid Δ⁹-tetrahydrocannabinol (Δ⁹-THC).

Design, setting, and participants

Healthy volunteers (n?=?30) participated in a three test day study during which they received 0.018 and 0.036 mg/kg of Δ⁹-THC, or placebo intravenously in a randomized, counterbalanced order under double-blind conditions.

Measurements

Primary outcome measures were subjective “high,” perceptual alterations, and memory impairment. Secondary outcome measures consisted of stimulatory and depressant subjective effects, attention, spatial memory, executive function, Δ⁹-THC and 11-hydroxy-THC blood levels, and other subjective effects. FH was calculated using the Family Pattern Density method and was used as a continuous variable.

Findings

Greater FH was correlated with greater “high” and perceptual alterations induced by Δ⁹-THC. This enhanced sensitivity with increasing FH was specific to Δ⁹-THC’s rewarding effects and persisted even when FH was calculated using an alternate method.

Conclusions

Enhanced sensitivity to the rewarding effects of Δ⁹-THC in high-FH volunteers suggests that alterations in CB₁R function might contribute to alcohol misuse vulnerability.