• Corpus ID: 75130947

Резюмета научните трудове на д-р инж Валентин Стойчев Лозанов

@inproceedings{2014,
  title={Резюмета научните трудове на д-р инж Валентин Стойчев Лозанов},
  author={},
  year={2014}
}

• Published 2014
• Biology

Polyamines are essential polycations, playing important roles in mammalian physiology. Theoretically, the involvement of homocysteine in polyamine synthesis via Sadenosylmethionine is possible; however, to our knowledge, it has not been established experimentally. Here, we propose an original approach for investigation of homocysteine metabolites in an animal model. The method is based on t he combination of isotope-labeled homocysteine supplementation and high-resolution accurate mass spectrometry analysis. Structural identity of the isotope-labeled metabolites was confirmed by accurate mass measurements of molecular and fragment ions and comparison of the retention times and tandem mass spectrometry fragmentation patterns. Isotope-labeled methionine, spermidine, and spermine were detected in all investigated plasma and tissue samples. The induction of moderate hyperhomocysteinemia leads to an alteration in polyamine levels in a different manner. The involvement of homocysteine in polyamine synthesis and modulation of polyamine levels could contribute to a better understanding of the mechanisms connected with homocysteine toxicity. 2) Ruseva, S., Vasileva, A., Aleksandrova, D., Lozanov, V., Mitev, V.Liquid Chromatography Orbitrap Mass Spectrometry Method for Analysis of Homocysteine and Related Aminothiols in Cereal Products (2014) Food Analytical Methods, 7 (4), pp. 865871; IF 1,802; цитирания 1. ABSTRACT: Liquid chromatography Orbitrap mass spectrometry method for quantification of biological aminothiols (cysteine, homocysteine, and glutathione) in cereal products has been developed. The assay is based on preliminary derivatization with N-(2-acridonyl)maleimide and high resolution accurate mass spectrometry with utilization of dl-Homocystine-3,3,3′,3′,4,4,4′,4′d8 (homocystine-d8) as internal standard. The limits of quantification for homocysteine, cysteine, and glutathione are 19.44, 40.78, and 338.93 pg, respectively, per 10 μl injection. Intraand interday precision expressed as relative standard deviations are in the range of 1.76 to 2.94 % and 1.06 to 4.13 %, respectively. The average recoveries were 98 % for Hcy, 87 % for Cys, and 92 % for GSH. Wheat, maize, and bakery products with different origin were analyzed. The content of Hcy in the investigated samples was found to be in range of 9-436 μg/100 g, Cys in range of 29-6,895 μg/100 g and GSH in range of 259-14,795 μg/100 g. Liquid chromatography Orbitrap mass spectrometry method for quantification of biological aminothiols (cysteine, homocysteine, and glutathione) in cereal products has been developed. The assay is based on preliminary derivatization with N-(2-acridonyl)maleimide and high resolution accurate mass spectrometry with utilization of dl-Homocystine-3,3,3′,3′,4,4,4′,4′d8 (homocystine-d8) as internal standard. The limits of quantification for homocysteine, cysteine, and glutathione are 19.44, 40.78, and 338.93 pg, respectively, per 10 μl injection. Intraand interday precision expressed as relative standard deviations are in the range of 1.76 to 2.94 % and 1.06 to 4.13 %, respectively. The average recoveries were 98 % for Hcy, 87 % for Cys, and 92 % for GSH. Wheat, maize, and bakery products with different origin were analyzed. The content of Hcy in the investigated samples was found to be in range of 9-436 μg/100 g, Cys in range of 29-6,895 μg/100 g and GSH in range of 259-14,795 μg/100 g. 3) Petkova, Z., Tchekalarova, J., Pechlivanova, D., Moyanova, S., Kortenska,L., Mitreva, R., Popov, D., Markova, P., Lozanov, V., Atanasova, D., Lazarov, N., Stoynev, A. Treatment with melatonin after status epilepticus attenuates seizure activity and neuronal damage but does not prevent the disturbance in diurnal rhythms and behavioral alterations in spontaneously hypertensive rats in kainate model of temporal lobe epilepsy (2014) Epilepsy and Behavior, 31, pp. 198-208; IF 2,061. ABSTRACT: Melatonin is involved in the control of circadian and seasonal rhythmicity, possesses potent antioxidant activity, and exerts a neuroprotective and anticonvulsant effect. Spontaneously hypertensive rats (SHRs) are widely accepted as an experimental model of essential hypertension with hyperactivity, deficient sustained attention, and alterations in circadian autonomic profiles. The purpose of the present study was to determine whether melatonin treatment during epileptogenesis can prevent the deleterious consequences of status epilepticus (SE) in SHRs in the kainate (KA) model of temporal lobe of epilepsy (TLE). Spontaneous recurrent seizures (SRSs) were EEGand video-recorded during and after the treatment protocol. Melatonin (10. mg/kg diluted in drinking water, 8. weeks) increased the seizure-latent period, decreased the frequency of SRSs, and attenuated the circadian rhythm of seizure activity in SHRs. However, melatonin was unable to affect the disturbed diurnal rhythms and behavioral changes associated with epilepsy, including the decreased anxiety level, depression, and impaired spatial memory. Melatonin reduced neuronal damage specifically in the CA1 area of the hippocampus and piriform cortex and decreased hippocampal serotonin (5-HT) levels both in control and epileptic SHRs. Although long-term melatonin treatment after SE shows a potential to attenuate seizure activity and neuronal loss, it is unable to restore epilepsyassociated behavioral abnormalities in SHRs. Melatonin is involved in the control of circadian and seasonal rhythmicity, possesses potent antioxidant activity, and exerts a neuroprotective and anticonvulsant effect. Spontaneously hypertensive rats (SHRs) are widely accepted as an experimental model of essential hypertension with hyperactivity, deficient sustained attention, and alterations in circadian autonomic profiles. The purpose of the present study was to determine whether melatonin treatment during epileptogenesis can prevent the deleterious consequences of status epilepticus (SE) in SHRs in the kainate (KA) model of temporal lobe of epilepsy (TLE). Spontaneous recurrent seizures (SRSs) were EEGand video-recorded during and after the treatment protocol. Melatonin (10. mg/kg diluted in drinking water, 8. weeks) increased the seizure-latent period, decreased the frequency of SRSs, and attenuated the circadian rhythm of seizure activity in SHRs. However, melatonin was unable to affect the disturbed diurnal rhythms and behavioral changes associated with epilepsy, including the decreased anxiety level, depression, and impaired spatial memory. Melatonin reduced neuronal damage specifically in the CA1 area of the hippocampus and piriform cortex and decreased hippocampal serotonin (5-HT) levels both in control and epileptic SHRs. Although long-term melatonin treatment after SE shows a potential to attenuate seizure activity and neuronal loss, it is unable to restore epilepsyassociated behavioral abnormalities in SHRs. 4) Tchekalarova, J.D., Ivanova, N.M., Pechlivanova, D.M., Atanasova, D., Lazarov, N., Kortenska, L., Mitreva, R., Lozanov, V., Stoynev, A. Antiepileptogenic and neuroprotective effects of losartan in kainate model of temporal lobe epilepsy (2014) Pharmacology Biochemistry and Behavior, 127, pp. 27-36; IF 2,820. ABSTRACT: Recently, we have shown that the blockade of AT1 receptor might be useful as an adjuvant treatment strategy for the prevention of oxidative stress and neurotoxicity caused by status epilepticus (SE) in rats. The purpose of the present study was to further assess the efficacy of long-term treatment with losartan (10 mg/kg), the selective AT1 receptor antagonist, during kainate (KA)-induced epileptogenesis in Wistar rats. Losartan treatment started after onset of SE and continued for 4 w eeks. The rats were videoand EEG-recorded for 3 months. Locomotor activity, anxiety and depressive-like behavior were evaluated 9 weeks after SE, when all rats had developed chronic epileptic state. Neuronal damage in hippocampus was analyzed by hematoxylin while serotonin (5-HT) levels in hippocampus by HPLC. AT1 receptor antagonism increased the latent seizure-free period and decreased the frequency of spontaneous motor seizures. Losartan positively affected epilepsy-provoked behavioral changes, including impulsivity, low anxiety level and depression in a phase-dependent manner and restored the changes in diurnal fluctuation of motor activity. Losartan exerted neuroprotection selectively in the CA1 area of the hippocampus in the KA-treated rats and lowered the 5-HT levels both in normal and abnormal conditions. Our findings suggest that the AT1 receptor antagonist exerts disease-modifying effects during KA-induced epileptogenesis and neuronal damage in CA1 Recently, we have shown that the blockade of AT1 receptor might be useful as an adjuvant treatment strategy for the prevention of oxidative stress and neurotoxicity caused by status epilepticus (SE) in rats. The purpose of the present study was to further assess the efficacy of long-term treatment with losartan (10 mg/kg), the selective AT1 receptor antagonist, during kainate (KA)-induced epileptogenesis in Wistar rats. Losartan treatment started after onset of SE and continued for 4 w eeks. The rats were videoand EEG-recorded for 3 months. Locomotor activity, anxiety and depressive-like behavior were evaluated 9 weeks after SE, when all rats had developed chronic epileptic state. Neuronal damage in hippocampus was analyzed by hematoxylin while serotonin (5-HT) levels in hippocampus by HPLC. AT1 receptor antagonism increased the latent seizure-free period and decreased the frequency of spontaneous motor seizures. Losartan positively affected epilepsy-provoked behavioral changes, including impulsivity, low anxiety level and depression in a phase-dependent manner and restored the changes in diurnal fluctuation of motor activity. Losartan exerted neuroprotection selectively in the CA1 area of the hippocampus in the KA-treated rats and lowered the 5-HT levels both in normal and abno