Pesticide residues in animal-derived food: Current state and perspectives

Pesticides are widely used in the cultivation and breeding of agricultural products all over the world. However, their direct use or indirect pollution in animal breeding may lead to residual accumulation, migration, and metabolism in animal-derived foods, posing potential health risks to humans through the food chain. Therefore, it is necessary to detect pesticide residues in animal-derived food using simple, reliable, and sensitive methods. This review summarizes sample extraction and clean-up methods, as well as the instrumental determination technologies such as chromatography and chromatography-mass spectrometry for residual analysis in animal-derived foods, including meat, eggs and milk. Additionally, we perspectives on the future of this field. This information aims to assist relevant researchers in this area, contribute to the development of ideas and novel technical methods for residual detection, metabolic research and risk assessment of pesticides in animal-derived food.

Comprehensive analysis of phospholipid in milk and their biological roles as nutrients and biomarkers

Phospholipids (PL) have garnered significant attention due to their physiological activities. Milk and other dairy products are important dietary sources for humans and have been extensively used to analyze the presence of PL by various analytical techniques. In this paper, the analysis techniques of PL were reviewed with the eight trigrams of phospholipidomics and a comprehensive fingerprint of 1295 PLs covering 8 subclasses in milk and other dairy products, especially. Technology is the primary productive force. Based on phospholipidomics technology, we further review the relationship between the composition of PL and factors that may be involved in processing and experimental operation, and emphasized the significance of the biological role played by PL in dietary supplements and biomarkers (production, processing and clinical research), and providing the future research directions.

Levels, Toxic Effects, and Risk Assessment of Pyrrolizidine Alkaloids in Foods: A Review

Pyrrolizidine alkaloids (PAs) are naturally occurring secondary metabolites of plants. To date, more than 660 types of PAs have been identified from an estimated 6000 plants, and approximately 120 of these PAs are hepatotoxic. As a result of PAs being found in spices, herbal teas, honey, and milk, PAs are considered contaminants in foods, posing a potential risk to human health. Here, we summarize the chemical structure, toxic effects, levels, and regulation of PAs in different countries to provide a better understanding of their toxicity and risk assessment. With recent research on the risk assessment of PAs, this review also discusses the challenges facing this field, aiming to provide a scientific basis for PA toxicity research and safety assessment.

Use of Transcriptomics to Reveal the Joint Immunotoxicity Mechanism Initiated by Difenoconazole and Chlorothalonil in the Human Jurkat T-Cell Line

It is very important to evaluate the immunotoxicity and molecular mechanisms of pesticides. In this study, difenoconazole and chlorothalonil were evaluated for immunotoxicity by using the human Jurkat T-cell line, and the EC50 were 24.66 and 1.17 mg/L, respectively. The joint exposure of difenoconazole and chlorothalonil showed a synergistic effect at low concentrations (lower than 10.58 mg/L) but an antagonistic effect at high concentrations (higher than 10.58 mg/L). With joint exposure at a concentration of EC10, the proportion of late apoptotic cells was 2.26- and 2.91-fold higher than that with exposure to difenoconazole or chlorothalonil alone, respectively. A transcriptomics analysis indicated that the DEGs for single exposure are associated with immunodeficiency disease. Single exposure to chlorothalonil was mainly involved in cation transportation, extracellular matrix organization, and leukocyte cell adhesion. Single exposure to difenoconazole was mainly involved in nervous system development, muscle contraction, and immune system processes. However, when the joint exposure dose was EC10, the DEGs were mainly involved in the formation of cell structures, but the DEGs were mainly involved in cellular processes and metabolism when the joint exposure dose was EC25. The results indicated that the immunotoxicological mechanisms underlying joint exposure to difenoconazole and chlorothalonil are different under low and high doses.

Multiomics reveals new biomarkers and mechanistic insights into the combined toxicity effects of 2,2',4,4',5,5'-hexachlorobiphenyl and atrazine exposures in MCF-7 cells

Humans are constantly exposed to complicated chemical mixtures from the environment and food rather than being exposed to a single pollutant. The underlying mechanisms of the complicated combined toxicity of endocrine disrupting chemicals (EDCs) are still mainly unexplored. In this study, two representative EDCs, 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) and atrazine (ATZ), were selected to explore their combined effects on MCF-7 cell proliferation at environmental exposure concentrations by an integrated analysis of metabolomics and transcriptomics. The results showed that 1 μM ATZ and PCB153 combined exposure significantly accelerated MCF-7 cell growth by 18.2%. More than 400 metabolites detected by UHPLC-QTOF/MS were used to observe metabolism differences induced by binary mixtures. Metabolomics analysis verified that ATZ and PCB153 exposure alone or in combination could have an additive effect on metabolism and induce significant disruption to glycolysis, purine metabolism and the TCA cycle, which provide energy demand and biosynthetic substrates for cell proliferation. Compared to PCB153 and ATZ exposure alone, a combined effect was observed in purine and pyrimidine metabolic pathways. Hexokinase 3 (HK3) and cytochrome P450 19 subfamily A1 (CYP19A1) were identified as differentially expressed genes based on transcriptomic analysis. By integrating metabolome and transcriptome analysis, the proliferation effects of ATZ and PCB153 were induced at low doses in MCF-7 cells through potential interference with the downstream transcription signaling of CYP19A1. Furthermore, molecular docking indicated that PCB153 and ATZ directly affected CYP19A1. Altogether, the regulation of pivotal metabolites and differentially expressed genes could provide helpful information to reveal the mechanism by which PCB153 and ATZ affect MCF-7 cell proliferation.

A national-scale distribution of organochlorine pesticides (OCPs) in cropland soils and major types of food crops in China: Co-occurrence and associated risks

Organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) that resist degradation in the environment. OCPs remain detectable in cropland systems in China. However, spatial distribution of OCPs across China and associated ecological and health risks, as well as the relationship between levels of OCPs in cropland soils and crops, remain to be elucidated. To fill these gaps, we conducted a national-scale characterization of 19 individual OCPs in cropland soils and food crops including cereals and legumes in China, which were on-spot sampled simultaneously. Sparse canonical correlation analysis was employed to investigate the co-occurrence of OCPs in cropland soils and corresponding food crops. The ecological soil screening levels and risk quotient method were adopted for ecological and health risk assessment, respectively. Dichlorodiphenyltrichloroethanes (DDTs) were dominant in cropland systems, with its levels ranging up to 337 and 22.8 μg/kg in cropland soils and food crops, respectively. The mean ∑OCP levels in cropland soils varied from below the limit of detection to 337 μg/kg. Peanuts were the most contaminated crop, in which endosulfans and hexachlorobenzene (HCB) were co-occurrent with those in cropland soils (correlation coefficient R = 0.999 and 0.947, respectively). Besides, lindane and β-endosulfan in rice were co-occurrent with those in cropland soils (R = 0.810 and 0.868, respectively). The componential ratio analysis indicated fresh inputs of technical DDT, lindane, chlordane, endosulfan, HCB and aldrin. Among these pesticides, ecological impacts of DDTs, lindane, aldrin and β-endosulfan could be expected. Human health risk assessment suggested that daily consumption of the OCP-contaminated food crops raises a health concern especially for male teens. It is concluded that OCPs remain present in cropland systems in China at levels that raise a concern for both environment and human health.

Integrated metabolomics and transcriptomics analysis reveals new biomarkers and mechanistic insights on atrazine exposures in MCF‑7 cells

Atrazine (ATZ) is a widely used herbicide worldwide and is a long-suspected endocrine-disrupting chemical. However, most endocrine-disrupting toxicity studies on ATZ have been based on animal models and those investigating inner mechanisms have only focused on a few genes. Therefore, the possible link between ATZ and endocrine-disrupting toxicity is still unclear. In this study, multi-omics and molecular biology techniques were used to elucidate the possible molecular mechanisms underlying the effect of ATZ exposure on MCF-7 proliferation at environmentally relevant concentrations. Our study is the first report on ATZ-induced one carbon pool by folate metabolic disorder in MCF-7 cells. A concentration of 1 μM ATZ yielded the highest cell viability and was selected for further mechanistic studies. A total of 34 significantly changed metabolites were identified based on metabolomic analysis, including vitamins, amino acids, fatty acids, and corresponding derivatives. Folate and pyridoxal have potential as biomarkers of ATZ exposure. One carbon pool by folate metabolic pathway was identified based on metabolic pathway analysis of the significantly altered pathways. Moreover, FTCD and MTHFD related to this pathway were further identified based on transcriptomic analysis and protein assays. Folate and different forms of 5,6,7,8-tetrahydrofolate, which participate in purine synthesis and associate with methyl groups (SOPC, arachidonic acid, and L-tryptophan) in one carbon pool by the folate metabolic pathway, potentially promote MCF-7 cell proliferation. These findings on the key metabolites and regulation of the related differentially expressed genes in folate metabolism will shed light on the mechanism of MCF-7 cell proliferation after ATZ exposure. Overall, this study provides new insights into the mechanistic understanding of toxicity caused by endocrine-disrupting chemicals.

Probing Massive Star Nucleosynthesis with Data on Metal-Poor Stars and the Solar System

Metal-poor stars were formed during the early epochs when only massive stars had time to evolve and contribute to the chemical enrichment. Low-mass metal-poor stars survive until the present and provide fossil records of the nucleosynthesis of early massive stars. On the other hand, short-lived radionuclides (SLRs) in the early solar system (ESS) reflect the nucleosynthesis of sources that occurred close to the proto-solar cloud in both space and time. Both the ubiquity of Sr and Ba and the diversity of heavy-element abundance patterns observed in single metal-poor stars suggest that some neutron-capture mechanisms other than the r-process might have operated in early massive stars. Three such mechanisms are discussed: the weak s-process in non-rotating models with initial carbon enhancement, a new s-process induced by rapid rotation in models with normal initial composition, and neutron-capture processes induced by proton ingestion in non-rotating models. In addition, meteoritic data are discussed to constrain the core-collapse supernova (CCSN) that might have triggered the formation of the solar system and provided some of the SLRs in the ESS. If there was a CCSN trigger, the data point to a low-mass CCSN as the most likely candidate. An 11.8 M⊙ CCSN trigger is discussed. Its nucleosynthesis, the evolution of its remnant, and the interaction of the remnant with the proto-solar cloud appear to satisfy the meteoritic constraints and can account for the abundances of the SLRs 41Ca, 53Mn, and 60Fe in the ESS.

A comprehensive analysis of metabolomics and transcriptomics reveals new biomarkers and mechanistic insights on DEHP exposures in MCF-7 cells

Di-(2-ethylhexyl) phthalate (DEHP) is one of the most important environmental pollutants and affects multiple pathways upon human exposure. DEHP could induce MCF-7 cell proliferation at a very low dose; however, the possible linkage between DEHP and the cell proliferation effect is still unclear. Here, we carried out a comprehensive metabolome and transcriptome analysis to depict the possible molecular mechanisms of the effect of DEHP exposure on MCF-7 proliferation. In this paper, MCF-7 cells treated with DEHP at a dose of 1 μM for 48 h were selected for metabolome and transcriptome analysis. Untargeted and targeted metabolomics identified 8 differential metabolites, including amino acids, purine, pyrimidine and nucleotides. The metabolite changes were associated with 9 metabolic pathways. Disorders in riboflavin, histidine, beta-alanine metabolism, and nitrogen metabolism caused by DEHP exposure are important concerns for MCF-7 proliferation. Moreover, a transcriptomics study of the MCF-7 cells found a total of 500 differentially expressed genes (DEGs). KEGG enrichment analyses showed that pathways in cancer had stronger responses. The results of integrated analysis of the interactions between the DEGs and metabolites revealed significant changes in the purine metabolism pathway, which will shed light on the mechanism of MCF-7 cell proliferation after DEHP exposure. Overall, this study depicts the possible contribution of DEHP exposure to MCF-7 cell proliferation and highlights the power of omics platforms to deepen the mechanistic understanding of toxicity caused by endocrine disrupting chemicals.

Reference interval establishment of full blood count extended research parameters in the multi-ethnic population of Malaysia

Haematological cellular structures may be elucidated using automated full blood count (FBC) analysers such as Unicel DxH 800 via cell population data (CPD) analysis. The CPD values are generated by calculating volume, conductivity, and five types of scatter angles of individual cells which would form clusters or populations. This study considered 126 CPD parameter values of 1077 healthy Malaysian adults to develop reference intervals for each CPD parameter. The utility of the CPD reference interval established may range from understanding the normal haematological cellular structures to analysis of distinct cellular features related to the development of haematological disorders and malignancies.

New primary mechanisms for the synthesis of rare 9Be in early supernovae

We present two new primary mechanisms for the synthesis of the rare nucleus (9)Be, both triggered by ν-induced production of (3)H followed by (4)He((3)H,γ)(7)Li in the He shells of core-collapse supernovae. For progenitors of ∼ 8M(⊙), (7)Li((3)H,n(0))(9)Be occurs during the rapid expansion of the shocked He shell. Alternatively, for ultra-metal-poor progenitors of ∼ 11-15 M(⊙), (7)Li(n,γ)(8)Li(n,γ)(9)Li(e(-)ν(e))(9)Be occurs with neutrons produced by (4)He(ν(e),e(+)n)(3)H, assuming a hard effective ν(e) spectrum from oscillations (which also leads to heavy element production through rapid neutron capture) and a weak explosion (so the (9)Be survives shock passage). We discuss the associated production of (7)Li and (11)B, noting patterns in LiBeB production that might distinguish the new mechanisms from others.

Long, cold, early r process? Neutrino-induced nucleosynthesis in He shells revisited

We revisit a ν-driven r-process mechanism in the He shell of a core-collapse supernova, finding that it could succeed in early stars of metallicity Z ≲ 10⁻³ Z(⊙), at relatively low temperatures and neutron densities, producing A ~ 130 and 195 abundance peaks over ~10-20 s. The mechanism is sensitive to the ν emission model and to ν oscillations. We discuss the implications of an r process that could alter interpretations of abundance data from metal-poor stars, and point out the need for further calculations that include effects of the supernova shock.

Flavor evolution of the neutronization neutrino burst from an O-Ne-Mg core-collapse supernova

We present results of 3-neutrino flavor evolution simulations for the neutronization burst from an O-Ne-Mg core-collapse supernova. We find that nonlinear neutrino self-coupling engineers a single spectral feature of stepwise conversion in the inverted neutrino mass hierarchy case and in the normal mass hierarchy case, a superposition of two such features corresponding to the vacuum neutrino mass-squared differences associated with solar and atmospheric neutrino oscillations. These neutrino spectral features offer a unique potential probe of the conditions in the supernova environment and may allow us to distinguish between O-Ne-Mg and Fe core-collapse supernovae.

Biological aerated filter treated textile washing wastewater for reuse after ozonation pre-treatment

The combination of chemical and biological treatment processes is a promising technique to reduce refractory organics from wastewater. Ozonation can achieve high color removal, enhance biodegradability, and reduce the chemical oxygen demand (COD). The biological technique can further decrease COD of wastewater after ozonation as a pre-treatment. In this study the ozonizing-biological aerated filter processes were used to treat textile washing wastewater for reuse after conventional treatment. The result showed that when the influent qualities were COD about 80 mg/L, color 16 degree and turbidity about 8 NTU, using the combination processes with the dosages of ozone at 30-45 mg/L with the hydraulic retention time (HRT) of biological aerated filter (BAF) at 3-4 hours respectively, gave effluent qualities of COD less than 30 mg/L, color 2 degree and turbidity less than 1NTU. The cost of treatment was less than one yuan/t wastewater, and these processes could enable high quality washing water reuse in textile industry.

Neutrino mass hierarchy and stepwise spectral swapping of supernova neutrino flavors

We examine a phenomenon recently predicted by numerical simulations of supernova neutrino flavor evolution: the swapping of supernova nu(e) and nu(mu,tau) energy spectra below (above) energy E(C) for the normal (inverted) neutrino mass hierarchy. We present the results of large-scale numerical calculations which show that in the normal neutrino mass hierarchy case, E(C) decreases as the assumed effective 2x2 vacuum nu(e)<==>nu(mu,tau) mixing angle (approximately theta13) is decreased. In contrast, these calculations indicate that E(C) is essentially independent of the vacuum mixing angle in the inverted neutrino mass hierarchy case. With a good neutrino signal from a future galactic supernova, the above results could be used to determine the neutrino mass hierarchy even if theta13 is too small to be measured by terrestrial neutrino oscillation experiments.

Coherent development of neutrino flavor in the supernova environment

We calculate coherent neutrino and antineutrino flavor transformation in the supernova environment, for the first time including self-consistent coupling of intersecting neutrino and antineutrino trajectories. For neutrino mass-squared difference /deltam2/ = 3 x 10(-3) eV2 we find that in the normal (inverted) mass hierarchy the more tangentially-propagating (radially-propagating) neutrinos and antineutrinos can initiate collective, simultaneous medium-enhanced flavor conversion of these particles across broad ranges of energy and propagation direction. Accompanying alterations in neutrino and antineutrino energy spectra and fluxes could affect supernova nucleosynthesis and the expected neutrino signal.

Evidence for lactate uptake after rat fluid percussion brain injury

Traumatic brain injury (TBI) places enormous early energy demand on brain tissue to reinstate normal ionic balance. Glucose declines and lactate increases after TBI as demonstrated in clinical and lab studies, suggesting increased glycolysis. This led us to hypothesize that high extracellular fluid (ECF) lactate may be beneficial after TBI. We measured cerebral dialysate lactate and glucose, and arterial lactate and glucose, before & after rat Fluid Percussion Injury (FPI) (2.06 +/- 0.13 atm) with and without i.v. lactate infusion (100 mM x 4.5 hours) to test the hypotheses that arterial lactate determines ECF lactate. 14C-lactate autoradiography was also performed, to demonstrate whether lactate is taken up by traumatized brain.

RESULTS

Dialysate lactate was always significantly higher than arterial. After lactate infusion, both the dialysate and the arterial lactate were significantly increased (P < 0.0001). Dialysate lactate increased within 10 min. following FPI, with significantly higher values in the lactate infusion group (82% higher with lactate infusion after FPI). Dialysate glucose fell following FPI, with a more severe decline in the saline group (129% lower), suggesting lactate infusion preserves or "spares" glucose in ECF. In our autoradiographic study, i.v. 14C-lactate accumulated at the injury site, with levels 2-4 times higher than in contralateral cortex. In conclusion, arterial lactate augmentation thus increases brain dialysate lactate and results in less reduction in ECF glucose, after FPI. Infused lactate accumulates at the injury site, where metabolism is probably the greatest.

Brain lactate uptake increases at the site of impact after traumatic brain injury

Although glucose is the main carbohydrate energy substrate for the normal brain, several studies published over the last 10 years now challenge this assumption. The activated brain increases its metabolism to meet increased energy demands by glycolysis after injury. In vitro studies now show that lactate alone can serve as an energy source to maintain synaptic function. In this study, we used 14C-lactate to test the hypothesis that blood lactate is acutely taken up by the injured brain, after fluid percussion injury (FPI) in the rat. 50 microCi radioactive lactate was injected i.v. immediately after FPI, in injured and sham rats. After 30 min, the brain was removed, frozen, and cut into 20 microm sections for autoradiography. Uptake of 14C-label was mainly concentrated at the injury site (2.5 times greater) although uninjured brain also took up the 14C-label. This increased concentration of radioactive lactate at the injury site suggests that the injured brain may use the lactate as an energy source.

Lactate/glucose dynamics after rat fluid percussion brain injury

Traumatic brain injury (TBI) places enormous early energy demand on brain tissue to reinstate normal ionic balance. Clinical studies have demonstrated a decline in extracellular fluid (ECF) glucose and an increase in lactate after TBI. In vitro studies suggest that this increase in lactate is mediated by increased glutamate and may provide a metabolic substrate for neurons, to aid in ionic restoration. This led us to hypothesize that high ECF lactate may be beneficial in recovery following TBI, where major ionic flux has been shown to occur. In this study, we measured cerebral dialysate lactate and glucose, and arterial lactate and glucose, before and after rat lateral fluid percussion brain injury (FPI; 2.06 +/- 0.13 atm) with and without IV lactate infusion (100 mM X 0.65 mL/h X 5 h) to test the hypothesis that arterial lactate can influence ECF lactate. Dialysate lactate increased within 10 min following FPI, with higher values in the lactate infusion group. Following FPI, the dialysate lactate increase was 238% with lactate infusion versus 171% increase with saline infusion. Dialysate glucose fell immediately following FPI, with a more severe decline in the saline group. The glucose decrease was 231% greater in the IV saline group. Furthermore, in the lactate infusion group, the dialysate glucose levels recovered to baseline levels by 4 h after injury, whereas they remained depressed through out the experiment, in the saline infusion group. We conclude that arterial lactate augmentation can increase brain dialysate lactate, and result in more rapid recovery of dialysate glucose after FPI. This may indicate a beneficial role for lactate, that may be potentially useful in the clinical situation, after TBI.

Role of protein kinase C and 72 kDa heat shock protein in ischemic tolerance following heat stress in the rat heart

Heat stress (HS) and the subsequent expression of 72 kDa heat shock protein (HSP 72) has been shown to enhance post-ischemic functional recovery and reduce infarct size. Because the synthesis of heat shock proteins involves activation of heat shock transcription factors through phosphorylation, we hypothesized that inhibition of protein kinase C (PKC) would block HS mediated protection and expression of HSP 72 in the heart. Five groups of rats were studied (1) Sham anesthetized, (2) HS group--animals were heat shocked by raising the whole body core temperature to 42 degrees C for 15 min, (3) Vehicle group--HS rats treated with 50% DMSO in saline, (4) PKC inhibitor-treated group--specific PKC antagonist, chelerythrine chloride (5 mg/kg, i.p) given 30 min prior to HS and (5) Vehicle treated control--non-HS rats treated with vehicle prior to ischemia/reperfusion. Hearts were subjected to 30 min of regional ischemia and 90 min of reperfusion 24 h after HS. Risk area was delineated by injection of 10% Evan's blue and infarct size determined using computer morphometry of tetrazolium stained sections. Infarct size (% area at risk) reduced significantly from 49.4 +/- 2.3% (n = 7) in sham to 10.0 +/- 2.5% (p < 0.01) and 9.1 +/- 3.0% in HS and vehicle treated HS groups respectively (p < 0.05) Treatment with chelerythrine prior to HS increased infarct size to 49.4 +/- 2.3% (p < 0.05). Infarct size in chelerythrine-treated non-HS ischemic/reperfused heart was 40.7 +/- 5.4%, which did not differ significantly from vehicle-treated sham group. Western blot analysis demonstrated marked increase in HSP 72 in HS groups (with or without vehicle treatment) and pretreatment with chelerythrine chloride failed to inhibit the expression of HSP 72. The results suggest that HS-induced ischemic tolerance is mediated via PKC pathway and this protection does not appear to be directly related to the expression of HSP 72 in rat heart.

Induction of 72-kDa heat shock protein does not produce second window of ischemic preconditioning in rat heart

Ischemic preconditioning (PC) induces delayed phase of protection, known as the second window of protection (SWOP). We investigated this phenomenon in rat and correlated it with the expression of 72-kDa heat shock protein (HSP 72). Rats were preconditioned with 1, 2, and 3 cycles of 5-min left anterior descending artery occlusions, each separated by a 10-min reperfusion (PC x 1, PC x 2 and PC x 3, respectively). Another group of rats was preconditioned with heat shock (HS) by raising temperature to 42 degreesC for 15 min. Twenty-four hours later, rats were given sustained ischemia for 30 min and 90 min of reperfusion. Infarct sizes (%risk area) were 40.0 +/- 7.5, 37.6 +/- 5.6, and 47.6 +/- 2.4 (mean +/- SE) for PC x 1, PC x 2, and PC x 3 hearts, respectively, which were not different from the sham (49.9 +/- 3.9, P > 0.05). In contrast, infarct size was reduced from 47.5 +/- 3.8% in sham to 4.7 +/- 2.3% (P < 0.01) 24 h after HS. Additionally, early PC significantly reduced infarct size from 47.5 +/- 3.8% in controls to 6.0 +/- 1.2 and 5.0 +/- 1.1% with PC x 1 and PC x 3. Repeated PC cycles induced over a threefold increase in HSP 70 mRNA after 2 h compared with sham (P < 0.05). HSP 72, which increased 24 h after PC or HS, was not significantly different between the two PC stimuli. We conclude that PC does not induce SWOP in rat heart despite enhanced expression of HSP 72. In contrast, HS-induced delayed protection was associated with enhanced accumulation of HSP 72. It is possible that SWOP and HS have distinct mechanisms of protection that may not be exclusively related to HSP 72 expression.

Pharmacologic preconditioning with monophosphoryl lipid A is abolished by 5-hydroxydecanoate, a specific inhibitor of the K(ATP) channel

We sought to determine the role of opening of adenosine triphosphate (ATP)-sensitive potassium channel (K(ATP) channel) in monophosphoryl lipid A (MLA)-induced myocardial protection after ischemia/reperfusion (I/R) in rabbit. We used 5-hydroxydecanoate (5-HD), an ischemia-selective inhibitor of K(ATP) channel, to block MLA-stimulated cardiac protection. Four groups of rabbits were studied: group I, MLA-vehicle; group II, MLA; group III, MLA + 5-HD; and group IV, 5-HD only. MLA (35 microg/kg, i.v.) or vehicle were given 24 h before I/R. 5-HD (5 mg/kg) was given 15 min before ischemia. All rabbits underwent 30-min coronary occlusion, followed by 3-h reperfusion. Area at risk was delineated by injection of Evan's blue, and infarct size was determined by tetrazolium staining. Pretreatment with MLA reduced infarct size (percentage of area at risk) from 40+/-8.6% to 15.1+/-1.5%. The infarct size increased to 51.9+/-5.8% with 5-HD in MLA-treated rabbits. 5-HD did not alter infarct size significantly when given in vehicle-treated control rabbits. These data suggest that MLA exerts its protective effect through activation of K(ATP) channel.

Dissociation of heat shock proteins expression with ischemic tolerance by whole body hyperthermia in rat heart

Heat shock (HS) results in the expression of heat shock proteins (hsp) and confers tolerance against subsequent ischemic injury. We examined the extent of myocardial protection in vivo, and determined the level of hsp expression induced by HS as a function of time. Anesthetized rats were subjected to HS by raising core temperature to 42 degrees C for 15 min and they were then allowed to recover from 2 to 30 h (n = 8-11 for each time point). At the appropriate time, animals were subjected to 30 min of ischemia via ligation of the LAD, followed by 90 min of reperfusion. Infarct size was determined by tetrazolium staining and hsp expression was assessed by Western blots. Following ischemia/reperfusion, the infarct sizes (% risk area) were 51.3 +/- 3.7, 41.0 +/- 7.7, 48.0 +/- 6.9 after 2, 4 and 12 h of HS, which were not significantly different from 39.2 +/- 2.75 in non heat-shocked animals (P > 0.05). In contrast, the infarct size was reduced significantly to 11.0 +/- 3.1% in 24 h HS group (P < 0.01 v non-heat-shocked control, 2, 4 and 12 h HS groups), but increased back to 40.0 +/- 3.2% (P < 0.01) by 30 h after HS. No major significant differences in the mean arterial blood pressure, heart rate or rate pressure product was observed between different groups. The synthesis of 72- and 27-kD hsp in HS groups was rapid, reaching > 80% of maximum within 4 h of initial insult and peaked by 12 h, whereas the protective effect of HS was absent at these time points. We conclude that ischemic tolerance afforded by HS cannot be solely explained on the basis of hsp expression, and may be dependent on factors such as post-translational modifications, translocation of hsps or some other as yet unidentified factors.

ATP-sensitive potassium channel mediates delayed ischemic protection by heat stress in rabbit heart

Heat shock protects against myocardial ischemia-reperfusion injury possibly via increased expression of heat shock proteins. The direct evidence of heat shock protein protection in vivo remains circumstantial, and no other new mechanism of protection has been proposed. Recent studies suggest that opening of ATP-sensitive K+ channels (KATP channels) plays an important role in ischemic preconditioning; however, it is not known whether this channel is also important in delayed protection conferred by heat shock. Anesthetized rabbits underwent heat shock treatment by raising core temperature to 42 degrees C for 15 min. Twenty-four hours later, the animals were reanesthetized and subjected to regional ischemia-reperfusion. The specific KATP channel blockers glibenclamide (0.3 mg/kg i.p.) and sodium 5-hydroxydecanoate (5HD; 5 mg/kg i.v.) were used to block the channel function. The drugs were administered at two different times, either pre-heat stress or preischemia. Infarct size was determined by triphenyltetrazolium chloride staining. The 72-kDa heat shock protein (HSP 72) was measured by Western blots. Our results show that heat shock produced a marked reduction in infarct size (39.4 +/- 8.1 to 14.3 +/- 2.5% of risk area, P < 0.05). Glibenclamide and 5HD completely abolished heat shock-induced reduction in infarct size (42.3 +/- 0.32 and 33.7 +/- 4.8%) when given before ischemia-reperfusion; however, these antagonists failed to block protection when administered before the onset of heat shock. Furthermore, the enhanced expression of HSP 72 in heat shock groups was not diminished by glibenclamide or 5HD, suggesting a lack of a direct role of this protein in conferring cardiac protection by heat shock. The complete blockade of cardiac protection by glibenclamide and 5HD strongly suggests that opening of this channel is a very important component of heat shock-induced ischemic protection in rabbit hearts.

Delayed preconditioning of cultured adult rat cardiac myocytes: role of 70- and 90-kDa heat stress proteins

We investigated the protective effect of heat stress and metabolic preconditioning in cultured adult rat cardiac myocytes and correlated this effect with induction of heat shock proteins (HSP). Myocytes were preconditioned with sublethal heat shock or metabolic preconditioning for 30 min. Twenty hours later, preconditioned myocytes were subjected to lethal heat shock (46 degrees C for 2 h) or ischemia by incubation in ischemic buffer for 2 h. Cellular injury index was reduced from 69 +/- 4.0% in lethally heat-shocked cells to 27.0 +/- 1.6% with heat shock preconditioning (mean +/- SE; P < 0.01) and 19.0 +/- 3.0% with metabolic preconditioning (P < 0.01). Cellular injury index was 81.0 +/- 1.0% in ischemic myocytes and was reduced to 25.9 +/- 2.7 and 21.4 +/- 2.6% in heat shock- and metabolic-preconditioned myocytes, respectively (P < 0.01). A significant cross-tolerance of myocytes against lethal injury was observed with the two preconditioning methods. Western blot analysis revealed 3.3- and 2.5-fold increases in HSP 90 and 500- and 15-fold increases in HSP 70 with heat shock and metabolic preconditioning, respectively. HSP 27 expression remained unaltered relative to control cells. We conclude that heat shock and metabolic preconditioning induce delayed tolerance against lethal injuries in adult cardiac myocytes with elevated levels of HSP 70 and HSP 90.

The ischemia-selective KATP channel antagonist, 5-hydroxydecanoate, blocks ischemic preconditioning in the rat heart

Although the KATP channel has been demonstrated to be involved in ischemic preconditioning (IPC) in most species, controversy still exists as to the role of this channel as a mediator of PC in the rat heart. Previously, the authors' laboratories have shown that glibenclamide blocks IPC in the intact rat heart, in a time-dependent manner; however, since glibenclamide has been shown to have non-selective effects unrelated to KATP channel blockade, a structurally dissimilar and ischemia-selective KATP channel blocker, 5-hydroxydecanoate (5-HD), was used to further elucidate the role of KATP channels in mediating IPC in the rat heart. Anesthetized, open-chested Sprague-Dawley rats were subjected to one of four protocols. In Group I, control (C), rats were subjected to 30 min of left coronary artery occlusion and 90 min of reperfusion. In Group II, IPC was elicited by 1 x 5 min occlusion followed by 10 min of reperfusion, prior to the 30 min occlusion and 90 min reperfusion periods, 5-HD (5 mg/kg, i.v.) was given 15 min prior to the 30 min occlusion period in non-preconditioned animals, or given 15 min prior to IPC (5-HD+IPC) (Groups III and IV, respectively). Infarct size (IS), as a percentage of the area at risk (AAR), was determined by triphenyltetrazolium staining. Ischemic preconditioning produced a marked reduction in infarct size (47.5 +/- 3.8% to 7.9 +/- 1.9%, *P < 0.01), which was completely abolished by 5-HD (50.5 +/- 2.6%). These data further suggest that the opening of KATP channels is an important component of IPC in the intact rat heart, similar to that observed in other species.

KATP channels in rat heart: blockade of ischemic and acetylcholine-mediated preconditioning by glibenclamide

The objective of this study was to examine if the opening of ATP-sensitive K+ (KATP) channels play an important role in ischemic preconditioning (PC) in the rat heart. A second goal was to test the role of acetylcholine (ACh) in mimicking PC and test if it could be blocked by KATP antagonist. Glibenclamide, a specific antagonist of the KATP channel, was given as two doses of 0.3 mg/kg each at 60 and 30 min before PC. Six groups of rats were subjected to ischemia and reperfusion (I/R) using these protocols: 1) control (I/R), 30-min ischemia followed by 90-min reperfusion (n = 6 rats); 2) preconditioned hearts given 5-min ischemia 10 min before I/R (n = 9 rats); 3) glibenclamide (0.3 mg/kg) treatment 60 and 30 min before PC (n = 13 rats); 4) glibenclamide treatment before I/R (n = 15 rats); 5) ACh infusion for 5 min (18 micrograms/ml) at a rate of 0.15 ml/min followed by equilibration for 10 min before I/R, n = 13 rats; and 6) glibenclamide treatment before ACh infusion followed by I/R (n = 11 rats). Preconditioning reduced the infarcted area (expressed as percent area at risk) from 42.0 +/- 4.4% in control to 8.7 +/- 6% (mean +/- SE, P < 0.05). Glibenclamide blocked the protection conferred by PC (39.1 +/- 4.5%, P < 0.05) without having a significant effect on control nonpreconditioned hearts. ACh infusion in lieu of PC also reduced infarct size to 25.0 +/- 5.63% (P < 0.05 compared with control), which was again blocked by glibenclamide (44.2 +/- 5.0%, P < 0.05). The data suggest that opening of KATP channels for ischemic and ACh-mediated preconditioning is also important in the rat heart.

Monophosphoryl lipid A induces pharmacologic 'preconditioning' in rabbit hearts without concomitant expression of 70-kDa heat shock protein

The purpose of this study was to evaluate the protective effect of a new endotoxin analogue, monophosphoryl lipid A (MLA) in a rabbit model of myocardial ischemia/reperfusion and to show if this protection was mediated via synthesis of 70 kDa heat shock protein (HSP 70). Three groups of New Zealand White rabbits underwent 30 min coronary occlusion, followed by 4 hours reperfusion. First group of rabbits (n = 6) were treated with 0.35 ml vehicle (40% propylene glycol, 10% ethanol in water). The second and third group of rabbits (n = 6-8) were treated with MLA (35 micrograms/kg, i.v.) 12 and 24 hours prior to ischemia and reperfusion. MLA treatment either 12 or 24 h prior to ischemia/reperfusion demonstrated significantly reduced infarct size (12.5 +/- 1.7 and 14.7 +/- 2.1% for 12 and 24 h) when compared with vehicle control (40.4 +/- 8.6%, mean +/- S.E.M, p < 0.05). No significant differences in the infarct size was observed between the 12 and 24 h MLA treated groups. The area at risk was not significantly different between the three groups. Baseline values of heart rate, systolic and diastolic blood pressure were not significantly different between the control and MLA treated groups. However, the systolic as well as diastolic blood pressure during reperfusion were significantly lower in rabbits treated with MLA. Western blot analysis of the protein extracts of the hearts (n = 2/group) demonstrated no increase in the expression of the inducible form of HSP 70 following treatment with MLA. We conclude that MLA has significant anti-infarct effect in rabbit which is not mediated by the cardioprotective protein HSP 70. The anti-infarct effect of this drug is superior to the reported protective effects of delayed ischemic or heat stress preconditioning. We hypothesize that the pharmacologic preconditioning afforded by MLA is accomplished via a unique pathway that bypasses the usual intracellular signaling pathways which lead to the myocardial protection with the expression of heat shock proteins.

Monophosphoryl lipid A induces pharmacologic 'preconditioning' in rabbit hearts without concomitant expression of 70-kDa heat shock protein

The purpose of this study was to evaluate the protective effect of a new endotoxin analogue, monophosphoryl lipid A (MLA) in a rabbit model of myocardial ischemia/reperfusion and to show if this protection was mediated via synthesis of 70 kDa heat shock protein (HSP 70). Three groups of New Zealand White rabbits underwent 30 min coronary occlusion, followed by 4 hours reperfusion. First group of rabbits (n = 6) were treated with 0.35 ml vehicle (40 % propylene glycol, 10 % ethanol in water). The second and third group of rabbits (n = 6-8) were treated with MLA (35 micrograms/kg, i.v.) 12 and 24 hours prior to ischemia and reperfusion. MLA treatment either 12 or 24 h prior to ischemia/reperfusion demonstrated significantly reduced infarct size (12.5 +/- 1.7 and 14.7 +/- 2.1% for 12 and 24 h) when compared with vehicle control (40.4 +/- 8.6%, mean +/- S.E.M, p < 0.05). No significant differences in the infarct size was observed between the 12 and 24 h MLA treated groups. The area at risk was not significantly different between the three groups. Baseline values of heart rate, systolic and diastolic blood pressure were not significantly different between the control and MLA treated groups. However, the systolic as well as diastolic blood pressure during reperfusion were significantly lower in rabbits treated with MLA. Western blot analysis of the protein extracts of the hearts (n = 2/group) demonstrated no increase in the expression of the inducible form of HSP 70 following treatment with MLA. We conclude that MLA has significant anti-infarct effect in rabbit which is not mediated by the cardioprotective protein HSP 70. The anti-infarct effect of this drug is superior to the reported protective effects of delayed ischemic or heat stress preconditioning. We hypothesize that the pharmacologic preconditioning afforded by MLA is accomplished via a unique pathway that bypasses the usual intracellular signaling pathways which lead to the myocardial protection with the expression of heat shock proteins.

Dehydroepiandrosterone inhibits human platelet aggregation in vitro and in vivo

The hypothesis has been advanced that the adrenal steroids dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) exert antiatherogenic and cardioprotective actions. Platelet activation has also been implicated in atherogenesis. To determine if DHEA and DHEAS affect platelet activation, the effects of these steroids on platelet aggregation were assessed both in vitro and in vivo. When DHEAS was added to pooled platelet-rich plasma before the addition of the agonist arachidonate, either the rate of platelet aggregation was slowed or aggregation was completely inhibited. Inhibition of platelet aggregation by DHEA was both dose- and time-dependent. Inhibition of platelet aggregation by DHEA was accompanied by reduced platelet thromboxane B2 (TxB2) production. Inhibition of platelet aggregation by DHEA was also demonstrated in vivo. In a randomized, double-blind trial, 10 normal men received either DHEA 300 mg (n = 5) or placebo capsule (n = 5) orally three times daily for 14 days. In one man in the DHEA group arachidonate-stimulated platelet aggregation was inhibited completely during DHEA administration, whereas in three other men in the DHEA group the rate of platelet aggregation was prolonged, and the sensitivity and responsiveness to agonist were reduced. None of the men in the placebo group manifested any change in platelet activity. These findings suggest that DHEA retards platelet aggregation in humans. Inhibition of platelet activity by DHEA may contribute to the putative antiatherogenic and cardioprotective effects of DHEA.

Oxidant stress increases heat shock protein 70 mRNA in isolated perfused rat heart

Ischemia/reperfusion (I/R) and preconditioning of the heart by coronary artery occlusions increase expression of heat shock protein 70 (HSP 70). Because free radicals are generated during I/R, we hypothesized that the oxidant stress might contribute to an increased expression of HSP 70. Isolated rat hearts were perfused with free radical-generating systems such as xanthine/xanthine oxidase (X/XO), irradiated rose bengal (RB) generating singlet oxygen, and H2O2 for 15 min followed by 30 min of recovery period. Significant decrease in developed pressure and coronary flow occurred after perfusion with X/XO, H2O2, and RB. During I/R, the developed pressure and coronary flow were 60 +/- 8 and 80 +/- 5%, respectively, of control, which improved significantly with superoxide dismutase. The expression of HSP 70 mRNA increased over 13-fold in hearts perfused with X/XO, 6- to 7-fold with RB, and over 5-fold with H2O2. With I/R, an over 10-fold increase in HSP 70 mRNA was observed, which decreased significantly in the presence of superoxide dismutase. These results demonstrate that oxidant stress directly increases HSP 70 mRNA in the rat heart. It is concluded that one of the potential mechanisms of expression of HSP 70 by I/R may be oxygen radicals.

Etiological role of Alternaria alternata in human esophageal cancer

In this paper, the mutagenicity and carcinogenicity of alternariol monomethyl ether (AME), alternariol (AOH), and their relevance to the etiology of human esophageal cancer were studied. These mycotoxins were produced by Alternaria alternata which was the main contaminating fungi isolated from the grain in Linxian County, an area with high incidence of esophageal cancer. This study demonstrated that: 1. AME and AOH might cause cell mutagenicity and transformation; 2. AME and AOH could combine with the DNA isolated from human fetal esophageal epithelium, activate the oncogens, c-H-ras and c-mys in it, and promote proliferation of human fetal esophageal epithelium in vitro; 3. squamous cell carcinoma of the fetal esophagus could be induced by AOH. According to the results of the studies of AME and AOH mentioned above, we consider that Alternaria alternata plays an important role in the etiology of human esophageal cancer.

[Enhancement of absorption of tetramethylpyrazine by synthetic borneol]

Sprague-Dawley rats were given ig tetramethylpyrazine phosphate (TMP) 5 mg/kg with or without previous borneol 5 mg/kg. The plasma TMP concentrations were analysed by GC method, and the data were treated by NONLIN program. The Cmax were 931 and 562 ng/ml, respectively, (P less than 0.01); while the AUC were 68,849 and 37,174, respectively, (P less than 0.05). It is suggested that the borneol enhances the absorption of the TMP but not in elimination.

Induction of mutagenesis and transformation by the extract of Alternaria alternata isolated from grains in Linxian, China

Alternaria alternata is commonly found in the grain in areas of high incidence of oesophageal cancer and is a suspected cancer-causing factor in Linxian, China. In this study, this fungus was isolated from corn in Linxian and cultured. The extract of this fungus was shown to induce 6-thioguanine-resistant mutants in V79 cells and cause transformation of NIH/3T3 mouse fibroblast cells. Metabolic activation does not seem to be required for these activities. The mutagenic and transforming activities of the extract of A. alternata suggest that this fungus may be a factor in the etiology of oesophageal cancer in Linxian.