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1.
J Biochem Mol Toxicol ; 37(4): e23304, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36636781

RESUMO

Hymexazol (HML) is widely used in agriculture as a systemic fungicide and plant growth promoter. Humans are continuously exposed to HML via various routes. The liver and kidneys are essential organs for the detoxification, metabolism, and excretion of HML. However, data concerning the impact of HML on nontarget organisms are scarce. The present study aimed to determine the mechanism of dose-dependent hepatorenal toxicity of HML in rats. Twenty-one rats were divided into three equal groups that received the following treatments via oral intake daily for 14 days: group 1, normal saline; group 2, low dose of HML (1/80 LD50 ); group 3, high dose of HML (1/40 LD50 ). We weighed the rats at the beginning and the end of the experiment to record the weight gain in each group. The results showed that HML induced dose-dependent hepatorenal toxicity manifested by a significant increase in malondialdehyde levels, a decrease in total antioxidant capacity and reduced glutathione contents, and upregulation of the transcriptase levels of the nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (TNF-α), and interleukin-1 beta (IL-1ß) genes. The HML-exposed groups displayed various histopathological changes in both organs, with significant elevation of all serum liver and kidney biomarkers. In conclusion, HML produced hepatorenal toxicity in rats through oxidative stress that mediates the NF-κB signaling pathway in response to pro-inflammatory cytokines such as TNF-α and IL-1ß. We advise limiting the use of HML in agricultural and veterinary practices and finding an alternative agent to avoid the human and animal health risks induced by HML exposure.


Assuntos
NF-kappa B , Fator de Necrose Tumoral alfa , Ratos , Humanos , Animais , NF-kappa B/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Fígado/metabolismo , Transdução de Sinais , Estresse Oxidativo
2.
Neurochem Res ; 47(10): 3051-3062, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35773501

RESUMO

Pesticides are widely used in agriculture to kill pests, but their action is non-selective and results in several hazardous effects on humans and animals. Pesticide toxicity has been demonstrated to alter a variety of neurological functions and predisposes to various neurodegenerative diseases. Although, there is no data available for hexaflumuron (HFM) and hymexazol (HML) neurotoxicity. Hence, the present study aims to investigate the possible mechanisms of HFM and HML neurotoxicity. 21 male Wistar rats were divided into three groups and daily received the treatment via oral gavage for 14 days as follows: group (1) normal saline, group (2) HFM (1/100LD50), and group (3) HML (1/100 LD50). Our results revealed that both HFM and HML produced a significant increase in MDA levels and a decrease in GSH and CAT activity in some brain areas. There were severe histopathological alterations mainly neuronal necrosis and gliosis in different examined areas. Upregulation of mRNA levels of JNK and Bax with downregulation of Bcl-2 was also recorded in both pesticides exposed groups. In all studied toxicological parameters, HML produced neurotoxicity more than HFM. HFM targets the cerebral cortex and striatum, while HML targets the cerebral cortex, striatum, hippocampus, and cerebellum. We can conclude that both HFM and HML provoke neurobehavioral toxicity through oxidative stress that impairs the mitochondrial function and activates the JNK-dependent apoptosis pathway.


Assuntos
Síndromes Neurotóxicas , Praguicidas , Animais , Benzamidas , Fluorocarbonos , Humanos , Masculino , Síndromes Neurotóxicas/metabolismo , Oxazóis , Estresse Oxidativo , Compostos de Fenilureia , Ratos , Ratos Wistar
3.
J Biochem Mol Toxicol ; 36(8): e23079, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35437878

RESUMO

Carbendazim (CBZ) is a common environmental pollutant that can contaminate food and water and severely damage human health. Some studies revealed the adverse effect of CBZ on different organs, but its detailed toxicity mechanism has not been elucidated yet. Thus, the present study aims to clarify the mechanisms of CBZ-induced hepatorenal toxicity in rats. Therefore, we partitioned 40 male Wistar rats into four groups (n = 10): a negative control group and three treatment groups, which received 100, 300, and 600 mg/kg of CBZ. All rats received the treatment daily by oral gavage. We collected blood and organ samples (liver and kidney) at 14 and 28 days postdosing. CBZ caused extensive pathological alterations in both the liver and kidneys, such as cellular degeneration and necrosis accompanied by severe inflammatory reactions in a dose- and time-dependent manner. All the CBZ-treated groups displayed strong tumor necrosis factor-α and nuclear factor-κB (NF-κB) immunopositivity. Additionally, CBZ dose-dependently elevated the alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, urea, and creatinine serum levels and reduced the serum albumin levels. Furthermore, CBZ-induced apoptosis, as indicated by the observed Bax gene upregulation and Bcl-2 gene downregulation in both organs. All these changes may be related to oxidative stress, as indicated by the increase in malondialdehyde levels and the decrease in total antioxidant capacity. Our results demonstrate that CBZ-induced dose- and time-dependent hepatorenal damage through oxidative stress, which activated both the NF-κB signaling pathway and Bcl-based programmed cell death.


Assuntos
Benzimidazóis , Carbamatos , Rim , Fígado , NF-kappa B , Estresse Oxidativo , Animais , Antioxidantes/metabolismo , Benzimidazóis/toxicidade , Carbamatos/toxicidade , Doença Hepática Induzida por Substâncias e Drogas , Rim/efeitos dos fármacos , Rim/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , NF-kappa B/metabolismo , Ratos , Ratos Wistar , Transdução de Sinais
4.
Nature ; 534(7606): 222-6, 2016 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-27279216

RESUMO

Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.

5.
Saudi Pharm J ; 30(9): 1315-1326, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36249946

RESUMO

The neonicotinoid insecticide imidacloprid has been linked to significant reproductive damage in mammals. Origanum majorana essential oil (OME) is a natural herbal product used in the management of many diseases due to its strong antioxidant effects. The oil was hydrodistilled from O. Majorana and analyzed using GC/MS then its possible protective mechanisms against IMI-induced reprotoxicity in male rats were investigated. 28-adult male Wistar rats were divided into 4 groups as follows: group (1) control group, group (2) OME, group (3) IMI, and group (4) IMI + OME. The treatments were applied daily via oral gavage for 60 days. Remarkable abnormalities in both territorial aggressive and sexual behaviors were observed in IMI-treated rats with a significant elevation of serum FSH and LH as well as altered testicular redox status. Along with inhibition of the testicular expression of StAR and aromatase genes and serum total testosterone in addition to abnormal sperm count, viability, motility, and morphology. Histopathological examination showed severe degeneration and necrosis in both germ cells and Leydig cells with atrophy in most of the seminiferous tubules. Co-administration of OME with IMI notably improved all the above-mentioned studied parameters, and restored rats' spermatogenesis, sexual behavior, and favorably modulates the levels of both testosterone and gonadotropic hormones via its potent antioxidant effect. These findings support the use of OME as a fertility enhancer and suggest that it could be used to manage pesticide-induced male infertility.

6.
Phys Rev Lett ; 123(21): 210501, 2019 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-31809160

RESUMO

We demonstrate diabatic two-qubit gates with Pauli error rates down to 4.3(2)×10^{-3} in as fast as 18 ns using frequency-tunable superconducting qubits. This is achieved by synchronizing the entangling parameters with minima in the leakage channel. The synchronization shows a landscape in gate parameter space that agrees with model predictions and facilitates robust tune-up. We test both iswap-like and cphase gates with cross-entropy benchmarking. The presented approach can be extended to multibody operations as well.

7.
Phys Rev Lett ; 121(9): 090502, 2018 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-30230854

RESUMO

Superconducting qubits are an attractive platform for quantum computing since they have demonstrated high-fidelity quantum gates and extensibility to modest system sizes. Nonetheless, an outstanding challenge is stabilizing their energy-relaxation times, which can fluctuate unpredictably in frequency and time. Here, we use qubits as spectral and temporal probes of individual two-level-system defects to provide direct evidence that they are responsible for the largest fluctuations. This research lays the foundation for stabilizing qubit performance through calibration, design, and fabrication.

8.
Phys Rev Lett ; 118(5): 057702, 2017 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-28211704

RESUMO

By analyzing the dissipative dynamics of a tunable gap flux qubit, we extract both sides of its two-sided environmental flux noise spectral density over a range of frequencies around 2k_{B}T/h≈1 GHz, allowing for the observation of a classical-quantum crossover. Below the crossover point, the symmetric noise component follows a 1/f power law that matches the magnitude of the 1/f noise near 1 Hz. The antisymmetric component displays a 1/T dependence below 100 mK, providing dynamical evidence for a paramagnetic environment. Extrapolating the two-sided spectrum predicts the linewidth and reorganization energy of incoherent resonant tunneling between flux qubit wells.

9.
Food Chem Toxicol ; 184: 114436, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38211767

RESUMO

Cyclophosphamide (CP) is broadly used to kill various tumor cells; however, its repeated uses have been reported to cause reproductive dysfunction and infertility. Natural flavonoid, rutin (RUT), possesses strong antioxidant and antiapoptotic activity that is attributed to ameliorate the reproductive dysfunction induced by CP. Many previous studies proved that the formulation of flavonoids in nanoemulsion has a promising perspective in mitigating the side effects of chemotherapy. Therefore, the main objective of this study was to investigate the ameliorative effects of RUT and RUT-loaded chitosan nanoparticles (RUT-CH NPs) against CP-induced reproductive dysfunction in male rats. For this aim, thirty-six male albino rats were randomly allocated into six groups as follows: control, RUT, RUT-CH NPs, CP, CP + RUT, and CP + RUT-CH NPs. In the CP groups, a single intraperitoneal injection of CP (150 mg/kg bwt) was administered on the first day of the experiment. RUT and RUT-CH NPs were orally administered either alone or with CP injection at a dose of 10 mg/kg bwt per day for 60 days. The results revealed that CP administration caused significant testicular oxidative stress damage through increasing the nitric oxide and malondialdehyde levels as well as decreasing the total antioxidant capacity and reduced glutathione contents. It also impaired spermatogenesis and steroidogenesis via altering the transcription levels of CYP11A1, HSD-3b, StAR, Bax, bcl-2, and Nrf-2 genes. Otherwise, the oral intake of either RUT or RUT-CH NPs with CP injection effectively attenuated these alterations and significantly improved the microscopic appearance of testicular tissue. In conclusion, this study highlights the potential of RUT either free or NPs in mitigating CP-induced testicular dysfunction via its antioxidant and anti-apoptotic properties.


Assuntos
Quitosana , Nanopartículas , Ratos , Masculino , Animais , Rutina/farmacologia , Antioxidantes/metabolismo , Quitosana/farmacologia , Testículo , Estresse Oxidativo , Ciclofosfamida/toxicidade , Flavonoides/farmacologia
10.
Int J Vet Sci Med ; 12(1): 11-24, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38487499

RESUMO

Stress in poultry production is energy-demanding. Nucleotides and yeast cell-wall products are essential nutrients for broiler performance, gut function, and immune response. Antibiotics, like florfenicol, negatively affect the immune system. A total of 600 one-d-old broiler chickens (Cobb-500) were weighed and randomly allotted into four groups with three replicates each. The control group (G1) received the basal diet, G2 received a diet supplemented with a combination of nucleotides and Saccharomyces cerevisiae derivatives (250 g/Ton), G3 received the basal diet and medicated with florfenicol (25 mg/Kg body weight) in drinking water for 5 days, while G4 received a combination of nucleotides and Saccharomyces cerevisiae-derivatives (250 g/Ton) and medicated with florfenicol in drinking water. Growth performance criteria were recorded weekly. Blood, intestinal contents, small-intestine sections, and litter samples were collected to measure birds' performance, carcass yields, leukocytic counts, antioxidant capacity, antibody titres, phagocytic index, caecal Clostridia, intestinal histomorphometry, and litter hygiene. Nucleotide-supplemented groups (G2 and G4) revealed significant (p ≤ 0.05) improvements in feed conversion, and body weight, but not for carcass yields in comparison to the control. Dietary nucleotides in G2 elevated blood total proteins, leucocytic count, antioxidant capacity, and phagocytic index, while they lowered blood lipids and litter moisture and nitrogen (p ≤ 0.05). Dietary nucleotides in G4 ameliorated the immunosuppressive effect of florfenicol (p ≤ 0.05) indicated in reducing caecal Clostridia, improving duodenal and ileal villi length, and increasing blood albumin and globulin levels, and phagocytosis%. Supplementing diets with nucleotides and yeast products has improved the immune system and provided a healthier gut for broilers.

11.
Neurotoxicology ; 98: 16-28, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37419146

RESUMO

Quercetin (Qu) is a powerful flavanol antioxidant that is naturally found in plants and is part of the flavonoid family. Qu has a wide range of biological properties, such as neuroprotective, anti-cancer, anti-diabetic, anti-inflammatory, and radical scavenging capabilities. However, the in vivo application of Qu is limited by its poor water solubility and low bioavailability. These issues could be addressed by utilizing Qu nanoformulations. Cyclophosphamide (CP) is a potent chemotherapeutic agent that causes severe neuronal damage and cognitive impairment due to reactive oxygen species (ROS) overproduction. The present study aimed to explore the proposed neuroprotective mechanism of quercetin (Qu) and quercetin-loaded Chitosan nanoparticles (Qu-Ch NPs) against the brain oxidative damage induced by CP in male albino rats. For this aim, thirty-six adult male rats were randomly divided into six groups (n = 6). Rats were pretreated with Qu and Qu-Ch NPs orally in doses of 10 mg/kg bwt/day for 2 weeks, and CP (75 mg/kg bwt) was administered intraperitoneally 24 h before the termination of the experiment. After 2 weeks, some neurobehavioral parameters were evaluated, and then euthanization was done to collect the brain and blood samples. Results showed that CP induces neurobehavioral deteriorations and impaired brain neurochemical status demonstrated by a significant decrease in brain glutathione (GSH), serum total antioxidant capacity (TAC), and serotonin (5-HT) levels while malondialdehyde (MDA), nitric oxide (NO), Tumor necrosis factor α (TNFα), and choline esterase (ChE) concentrations increased significantly compared to the control group. Pretreatment with Qu and Qu-Ch NPs showed a significant anti-oxidative, anti-depressive, and neuroprotective effect through modification of the above-mentioned parameters. The results were further validated by assessing the expression levels of selected genes in brain homogenates and histopathological investigations were done to pinpoint the exact brain-altered regions. It could be concluded that Qu and Qu-Ch NPs can be useful neuroprotective adjunct therapy to overcome neurochemical damage induced by CP.


Assuntos
Fármacos Neuroprotetores , Quercetina , Ratos , Animais , Quercetina/farmacologia , Antioxidantes/metabolismo , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo , Ciclofosfamida/toxicidade , Ciclofosfamida/metabolismo , Transdução de Sinais , Anti-Inflamatórios/farmacologia , Encéfalo
12.
ACS Omega ; 8(21): 18491-18508, 2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-37273614

RESUMO

Imidacloprid (IMI) insecticide is rapidly metabolized in mammals and contributes to neurotoxicity via the blocking of nicotinic acetylcholine receptors, as in insects. Origanum majorana retains its great antioxidant potential in both fresh and dry forms. No data is available on the neuroprotective effect of this plant in laboratory animals. In this context, aerial parts of O. majorana were used to prepare the essential oil (OMO) and methanol extract (OME). The potential neuroprotective impact of both OMO and OME against IMI-induced neurotoxicity in rats was explored. Forty-two rats were divided into 6 groups, with 7 rats in each one. Rats were daily administered the oral treatments: normal saline, OMO, OME, IMI, IMI + OMO, and IMI + OME. Our results revealed the identification of 55 components in O. majorana essential oil, most belonging to the oxygenated and hydrocarbon monoterpenoid group. Moreover, 37 constituents were identified in the methanol extract, mostly phenolics. The potent neurotoxic effect of IMI on rats was confirmed by neurobehavioral and neuropathological alterations and a reduction of both acetylcholine esterase (AchE) activity and dopamine (DA), serotonin (5HT), and γ-aminobutyric acid (GABA) levels in the brain. Exposure of rats to IMI elevates the malondialdehyde (MDA) levels and reduces the antioxidant capacity. IMI could upregulate the transcription levels of nuclear factor-κB (NF-κB), interleukin-1 ß (IL-1ß), and tumor necrosis factor (TNF-α) genes and express strong caspase-3 and inducible nitric oxide synthase (iNOS) immunostaining in most examined brain areas. On the other hand, rats coadministered OMO or OME with IMI showed a marked improvement in all of the studied toxicological parameters. In conclusion, cotreatment of O. majorana extracts with IMI can protect against IMI neurotoxicity via their potent antioxidant, anti-inflammatory, and anti-apoptotic effects. Thus, we recommend a daily intake of O. majorana to protect against insecticide's oxidative stress-mediated neuroinflammatory stress and apoptosis. The molecular docking study of linalool, rosmarinic acid, γ-terpene, and terpene-4-ol justify the observed normalization of the elevated iNOS and TNF-α levels induced after exposure to IMI.

13.
Environ Sci Pollut Res Int ; 29(19): 29091-29104, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34993831

RESUMO

Pesticides are viewed as a major wellspring of ecological contamination and causing serious risky consequences for people and animals. Imidacloprid (IM) and hexaflumuron (HFM) are extensively utilized insect poisons for crop assurance on the planet. A few investigations examined IM harmfulness in rodents, but its exact mechanism hasn't been mentioned previously as well as the toxicity of HFM doesn't elucidate yet. For this reason, the present study was designed to explore the mechanism of each IM and HFM-evoked rat liver and kidney toxicity and to understand its molecular mechanism. 21 male Wistar albino rats were divided into 3 groups, as follows: group (1), normal saline; group (2), IM; and group (3), HFM. Both insecticides were orally administered every day for 28 days at a dose equal to 1/10 LD50 from the active ingredient. After 28 days postdosing, rats were anesthetized to collect blood samples then euthanized to collect liver and kidney tissue specimens. The results showed marked changes in walking, body tension, alertness, and head movement with a significant reduction in rats' body weight in both IM and HFM receiving groups. Significant increases in MDA levels and decrease of GHS levels were recorded in liver and kidney homogenates of either IM or HFM groups. Liver and kidney tissues obtained from both pesticide receiving groups showed extensive histopathological alterations with a significant increase in the serum levels of ALT, AST, urea, and creatinine and a decrease in total proteins, albumin, and globulin levels. In addition, there was upregulation of the transcript levels of casp-3, JNK, and HO-1 genes with strong immunopositivity of casp-3, TNF-á½°, and NF-KB protein expressions in the liver and kidneys of rats receiving either IM or HFM compared with the control group. In all studied parameters, HFM caused hepatorenal toxicity more than those induced by IM. We can conclude that each IM and HFM provoked liver and kidneys damage through overproduction of ROS, activation of NF-KB signaling pathways and mitochondrial/JNK-dependent apoptosis pathway.


Assuntos
Antioxidantes , Estresse Oxidativo , Animais , Antioxidantes/metabolismo , Benzamidas/química , Fluorocarbonos/química , Humanos , Rim/metabolismo , Fígado/metabolismo , Masculino , Neonicotinoides/química , Nitrocompostos/química , Compostos de Fenilureia/química , Ratos , Ratos Wistar
14.
Nat Commun ; 12(1): 1761, 2021 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-33741936

RESUMO

Quantum computing can become scalable through error correction, but logical error rates only decrease with system size when physical errors are sufficiently uncorrelated. During computation, unused high energy levels of the qubits can become excited, creating leakage states that are long-lived and mobile. Particularly for superconducting transmon qubits, this leakage opens a path to errors that are correlated in space and time. Here, we report a reset protocol that returns a qubit to the ground state from all relevant higher level states. We test its performance with the bit-flip stabilizer code, a simplified version of the surface code for quantum error correction. We investigate the accumulation and dynamics of leakage during error correction. Using this protocol, we find lower rates of logical errors and an improved scaling and stability of error suppression with increasing qubit number. This demonstration provides a key step on the path towards scalable quantum computing.

15.
Science ; 360(6385): 195-199, 2018 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-29650670

RESUMO

A key step toward demonstrating a quantum system that can address difficult problems in physics and chemistry will be performing a computation beyond the capabilities of any classical computer, thus achieving so-called quantum supremacy. In this study, we used nine superconducting qubits to demonstrate a promising path toward quantum supremacy. By individually tuning the qubit parameters, we were able to generate thousands of distinct Hamiltonian evolutions and probe the output probabilities. The measured probabilities obey a universal distribution, consistent with uniformly sampling the full Hilbert space. As the number of qubits increases, the system continues to explore the exponentially growing number of states. Extending these results to a system of 50 qubits has the potential to address scientific questions that are beyond the capabilities of any classical computer.

16.
Science ; 358(6367): 1175-1179, 2017 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-29191906

RESUMO

Quantized eigenenergies and their associated wave functions provide extensive information for predicting the physics of quantum many-body systems. Using a chain of nine superconducting qubits, we implement a technique for resolving the energy levels of interacting photons. We benchmark this method by capturing the main features of the intricate energy spectrum predicted for two-dimensional electrons in a magnetic field-the Hofstadter butterfly. We introduce disorder to study the statistics of the energy levels of the system as it undergoes the transition from a thermalized to a localized phase. Our work introduces a many-body spectroscopy technique to study quantum phases of matter.

17.
Mol Cell Endocrinol ; 117(2): 157-65, 1996 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-8737375

RESUMO

A methanolic extract of 350,000 adult grey fleshflies Neobellieria bullata, was prepared and screened for myotropic activity. After fractionation on the first column, all fractions were screened in two heterologous (Locusta oviduct and Leucophaea hindgut) and one homologous (Neobellieria hindgut) myotropic bioassay. We here report the purification of one fraction, which stimulates the contractions of the Locusta oviduct. Electrospray Mass Spectrometry of the peptide revealed a molecular mass of 1395.82. The primary structure has been determined as AYRKPPFNGSLF-amide. This novel peptide was designated Neb-LF-amide. This sequence is different from the other known myotropic peptides in insects. The threshold concentration of the synthetic peptide is 1 x 10(-7) M on the Locusta oviduct. On the hindgut of Neobellieria or Leucophaea, the synthetic peptide is not active. By use of a polyclonal antiserum raised against the synthetic peptide, immunoreactivity was localized in median neurosecretory cells in the pars intercerebralis of the fly brain, indicating that Neb-LF-amide is a neuropeptide.


Assuntos
Dípteros/química , Neuropeptídeos/isolamento & purificação , Oligopeptídeos/isolamento & purificação , Sequência de Aminoácidos , Animais , Espectrometria de Massas , Dados de Sequência Molecular , Neuropeptídeos/química , Neuropeptídeos/metabolismo , Oligopeptídeos/química , Oligopeptídeos/metabolismo
18.
Biol Cybern ; 67(4): 309-22, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1515510

RESUMO

We propose a function-oriented model of the visual cortex. The model addresses an essential task of the visual system: to detect and represent objects. These are defined as sets, which reappear in the input with invariant inner relations. A network, incorporating an idealized description of anatomical and physiological data, is presented with a movie showing various moving objects. In the course of time, as a result of Hebbian plasticity, a connection scheme develops which embodies in its forward and lateral connections the information necessary to perform the operations involved in object recognition. We demonstrate that coherent neural activity can exploit this information. Two types of coherence have to be distinguished in this respect. Rate coherence performs invariance operations and association, while event coherence accomplishes segmentation tasks. The model reproduces and explains experimental findings made both in physiological recordings from the visual cortex and in psychophysical studies.


Assuntos
Modelos Neurológicos , Reconhecimento Visual de Modelos/fisiologia , Córtex Visual/fisiologia , Animais , Humanos , Matemática
19.
Appl Microbiol Biotechnol ; 62(2-3): 140-50, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12759790

RESUMO

Various techniques are used to adjust the flavors of foods and beverages to new market demands. Although synthetic flavoring chemicals are still widely used, flavors produced by biological methods (bioflavors) are now more and more requested by consumers, increasingly concerned with health and environmental problems caused by synthetic chemicals. Bioflavors can be extracted from plants or produced with plant cell cultures, microorganisms or isolated enzymes. This Mini-Review paper gives an overview of different systems for the microbial production of natural flavors, either de novo, or starting with selected flavor precursor molecules. Emphasis is put on the bioflavoring of beer and the possibilities offered by beer refermentation processes. The use of flavor precursors in combination with non-conventional or genetically modified yeasts for the production of new products is discussed.


Assuntos
Cerveja , Aromatizantes , Cerveja/análise , Benzaldeídos/metabolismo , Produtos Biológicos/metabolismo , Diacetil/metabolismo , Fermentação , Aromatizantes/metabolismo , Tecnologia de Alimentos , Engenharia Genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Enxofre/metabolismo , Trichoderma/metabolismo
20.
Gen Comp Endocrinol ; 90(3): 364-71, 1993 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8224763

RESUMO

A heptapeptide was isolated from brain-corpora cardiaca-corpora allata-suboesophageal ganglion extracts of the locust, Locusta migratoria. Biological activity was monitored during HPLC purification by observing the myotropic effect of column fractions on the isolated hindgut of Leucophaea maderae. The primary structure of this myotropic peptide was established as: Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2. The chromatographic and biological properties of the synthetic peptide were the same as those of the native peptide, thus confirming structural analysis. This heptapeptide is identical to the carboxyterminal heptamer of AKH-I and therefore designated as AKH-I4-10. AKH-I4-10 has no adipokinetic activity. AKH-I4-10 is most likely a breakdown product of Lom-AKH-I, suggesting that an endopeptidase which cleaves between Asn and Phe is present in the brain complex of L. migratoria. Such an endopeptidase has recently been characterized in in synaptic membranes of the nervous system of Schistocerca gregaria.


Assuntos
Gafanhotos/metabolismo , Hormônios de Inseto , Sequência de Aminoácidos , Aminoácidos/análise , Animais , Cromatografia Líquida de Alta Pressão , Sistema Digestório/química , Sistema Digestório/metabolismo , Fenômenos Fisiológicos do Sistema Digestório , Feminino , Gânglios dos Invertebrados/química , Gânglios dos Invertebrados/metabolismo , Hormônios de Inseto/análise , Hormônios de Inseto/biossíntese , Hormônios de Inseto/isolamento & purificação , Dados de Sequência Molecular , Análise de Sequência
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