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General Physiology and Biophysics

Volume 36, 2017, No. 3


  Influence of static magnetic fields in phototaxis and osmotic stress in Gymnodinium catenatum (Dinophyceae)
Paulo Vale 1)

1)The Portuguese Sea and Atmosphere Institute, I. P. (IPMA, IP), Sea and Marine Resources Department (DMRM), Avenida de Brasília s/n, 1449-006 Lisbon, Portugal.

Phototaxis response of the toxic microalgae Gymnodinium catenatum was studied in vitro. The percentage of cells remaining at mid-depth 20 min after stirring increased with solar radio, X-ray and solar flares output. It also increased with geomagnetic activity and temperature, and was dependent on culture time. Increase in the local static magnetic field with a permanent magnet did not influence the positive phototaxis response. However, survival and growth to a provoked hypo-osmotic shock in an altered static magnetic field was dependent on culture time and geomagnetic activity at a threshold below 22 nT. The results from phototaxis and hypo-osmotic shock experiments were in line with the previous hypothesis for the existence of two separate deleterious mechanisms conditioning the natural blooms of G. catenatum: one that is dependent on solar radiation and the other that is related to geomagnetic activity. Variations in electromagnetic fields caused by tectonic activity were also capable of influencing G. catenatum phototaxis and growth response in vitro.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 235-245.

  NADP-dependent enzymes are involved in response to salt and hypoosmotic stress in cucumber plants
Veronika Hýsková 1), Veronika Plisková, Václav Červený, Helena Ryšlavá

1)Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, Prague 2, 128 43, Czech Republic.

Salt stress is one of the most damaging plant stressors, whereas hypoosmotic stress is not considered to be a dangerous type of stress in plants and has been less extensively studied. This study was performed to compare the metabolism of cucumber plants grown in soil with plants transferred to distilled water and to a 100 mM NaCl solution. Even though hypoosmotic stress caused by distilled water did not cause such significant changes in the relative water content, Na+/K+ ratio and Rubisco content as those caused by salt stress, it was accompanied by more pronounced changes in the specific activities of NADP-dependent enzymes. After 3 days, the specific activities of NADP-isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase, NADP-malic enzyme and non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase in leaves were highest under hypoosmotic stress, and lowest in plants grown in soil. In roots, salt stress caused a decrease in the specific activities of major NADP-enzymes. However, at the beginning of salt stress, NADP-galactose-1-dehydrogenase and ribose-1-dehydrogenase were involved in a plant defense response in both roots and leaves. Therefore, the enhanced demands of NADPH in stress can be replenished by a wide range of NADP-dependent enzymes.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 247-258.

  Combination of bacteriolytic therapy with magnetic field for Ehrlich tumour treatment
Fadel Ali 1), Reem El-Gebaly, Amany Hamad

1)Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt.

Referable to the limited response of the current available cancer treatment modalities, new effective cancer fighting treatments are needed. This work investigates the efficiency of intratumoural injection of Pseudomonas aeruginosa bacteria combined with a local tumour exposure to extremely low frequency square pulsed magnetic field (ELF SPMF) in the mouse Ehrlich tumour. 64 Ehrlich ascites tumour-implanted female albino BALB/C mice were equally split up into 4 groups. Group 1 (GP1) was the positive control group. Group 2 (GP2) received a single intratumoural injection of P. aeruginosa bacteria. Group 3 (GP3) was exposed to ELF SPMF for tumour local exposure. Group 4 (GP4) was treated with P. aeruginosa intratumoural injection followed by local exposure of the tumour to ELF SPMF. Treatment monitoring was evaluated using ultrastructural examination, flow cytometry analysis in addition to the measurement of tumour dielectric properties. Tumour cell apoptosis was obvious in GP2 and GP4, but, with higher severity and percentages in GP2. Tumour biophysical properties revealed a significant increase in static conductivity σS of GP2, and decreases in dielectric increment Δɛ´of both GP2 and GP4 compared to the GP1. Unfortunately, GP2 mice showed severe signs of toxicity. We advocate the utilization of the combination of P. aeruginosa and SPMF to yield the most effective antitumour agent with less bacteria-related toxicity.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 259-271.

  Infrared spectroscopic investigation of erythrocyte membrane-smoke interactions due to chronic cigarette smoking
Mahmoud Sherif 1), Ali Mervat, Aly Eman

1)Biophysics and Laser Science Unit, Research Institute of Ophthalmology, 2 Al-Ahram Street, Giza, Egypt.

Cigarette smoking is a serious health problem throughout the world, with a complicated and not totally clear bio-effect. In this study, erythrocytes were obtained from healthy male volunteers aged 22 ± 2 years and, the possible effects of three cigarette smoking rates namely 10, 15 and 20 cigarette/day on erythrocytes membrane characteristics were examined by Fourier transform infrared spectroscopy (FTIR). The results of this study indicate many smoking-dependent variations on erythrocytes membrane without an obvious dose-response relationship. There was disruption in the acyl chain packing; changes in membrane order and phases as well as membrane proteins becoming more folded. These physico-chemical changes should have an impact on the function of erythrocytes and may explain the complex interaction of cigarette smoke mainstream with erythrocyte membrane and to some extent clarify the pathological processes associated with cigarette smoking.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 273-280.

  Up-regulation of nitric oxide synthases by erythropoietin alone or in conjunction with ischemic preconditioning in ischemia reperfusion injury of rat kidneys
Mohammed Elshiekh 1), Mehri Kadkhodaee, Behjat Seifi, Mina Ranjbaran, Hassan Askari

1)Department of Physiology, Faculty of Medicine, Tehran University of Medical Sciences, International campus, Tehran, Iran.

The effects of erythropoietin (EPO) alone or in conjunction with ischemic preconditioning (IPC) on nitric oxide synthase as well as comparing their effects on oxidative stress and proinflammatory cytokines are studied. Rats underwent bilateral renal ischemia of 50 min followed by 24 h reperfusion. They were administered EPO (5000 iu/kg i.p.) and/or subjected to IPC and sacrificed after 24 h, then plasma and tissue samples were obtained. Treatment of either EPO or IPC and their combination attenuates oxidative stress, decreases histological damages, inhibits proinflammatory response, and up-regulates iNOS and eNOS gene expression compared to IR group. In addition, EPO+IPC and EPO treatment produced significant up-regulation in iNOS gene expression compared to IPC group. In IPC and EPO+IPC groups, more powerful effect on up-regulation of eNOS gene expression was shown compared to EPO group. Our findings suggest that treatment with EPO or IPC and their combination improve renal function and preserve tubular damage induced by IR injury. These advantageous effects were closely related to reducing oxidative stress, suppressing proinflammatory response and enhancing generation of NO. IPC was more powerful in enhancement of eNOS gene expression compared to EPO that was more effective in increasing of iNOS gene expression.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 281-288.

  Postsynaptic zinc potentiation elicited by KCl depolarization at hippocampal mossy fiber synapses
Fatima Bastos 1), Sandra Lopes, Vanessa Corceiro, Carlos Matias, Jose Dionísio, Fernando Sampaio dos Aidos, Paulo Mendes, Rosa Santos, Rosa Quinta-Ferreira, M. Emilia Quinta-Ferreira

1)CNC, University Coimbra, Portugal.

The hippocampal mossy fibers contain a substantial quantity of loosely-bound zinc in their glutamatergic presynaptic vesicles, which is released in synaptic transmission processes. Despite the large number of studies about this issue, the zinc changes related to short and long-term forms of potentiation are not totally understood. This work focus on zinc signals associated with chemically-induced mossy fiber synaptic plasticity, in particular on postsynaptic zinc signals evoked by KCl depolarization. The signals were detected using the medium affinity fluorescent zinc indicator Newport Green. The application of large concentrations of KCl, 20 mM and 60 mM, in the extracellular medium evoked zinc potentiations that decreased and remained stable after washout of the first and the second media, respectively. These short and long-lasting enhancements are considered to be due to zinc entry into postsynaptic neurons. We have also observed that following established zinc potentiation, another application of 60 mM KCl only elicited further enhancement when combined with external zinc. These facts support the idea that the KCl-evoked presynaptic depolarization causes higher zinc release leading to zinc influx into the postsynaptic region.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 289-296.

  The protective role of folic acid against testicular dysfunction in lead-intoxicated rat model
Asmaa Gomaa 1), Nasser Abou Khalil, Mohammed Abdel-Ghani

1)Department of Medical Physiology, Faculty of Medicine, Assiut University, Assiut, Egypt.

There is an increasing concern over male reproductive toxicity caused by lead exposure. Folic acid (FA) is supposed to be a promising therapeutic strategy against lead toxicity. Therefore, the aim of this experimental study was to shed light on the potential protective role of FA on lead-induced testicular dysfunction in rats and its possible underlying mechanistic pathways. Rats (n = 24) were divided into four groups: Control, FA, Lead, and FA+Lead group. After 4 weeks, lead intoxication resulted in a marked reduction in the relative testicular weight and the serum level of testosterone, an impairment in the characters of semen analysis, and an increased content of lead, malondialdehyde and both interleukin-6 and -10 and a decreased antioxidant enzyme levels in the testicular tissue homogenate. Furthermore, marked degenerative histological changes and an increased expression of NF-κB were also noticed in the testicular tissue of Lead group. Supplementation of FA in association with lead considerably alleviated these adverse outcome responses most probably owing to its cytoprotective ability as emerged from combating the oxidative stress and inflammatory reactions. We concluded that FA could act as a highly effective fighting approach against lead-associated testicular toxicity.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 297-308.

  Involvement of oxidative stress in the mechanism of p,p’-DDT-induced nephrotoxicity in adult rats
Neila Marouani 1), Dorsaf Hallegue, Mohsen Sakly, Moncef Benkhalifa, Khemais Ben Rhouma, Olfa Tebourbi

1)Laboratory of Integrated Physiology, Faculty of Sciences, Bizerte, Carthage University, Jarzouna, Tunisia.

The 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (p,p’-DDT) is an organochlorine pesticide that persists in the environment and has a risk to human health. We investigated whether p,p'-DDT-induces nephrotoxicity in rats and whether oxidative stress and apoptosis are involved in the pathogenesis of this process. Male rats received the pesticide at doses of 50 and 100 mg/kg for 10 days. Renal damage was evaluated by histopathological examination and serum markers. The oxidative stress was evaluated by lipid peroxidation (LPO), metallothioneins (MTs) and protein carbonyl levels. Antioxidant enzymes were assessed by determination of superoxide dismutase (SOD) and catalase (CAT) activities. Glutathione-dependent enzymes and reducing power in kidney were evaluated by glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST) activities. Renal tubular cells apoptosis was assessed through the TUNEL assay. After 10 days of treatment, an increase of serum creatinine and urea levels occurred, LPO and protein carbonyl levels were increased, while MTs level, SOD and CAT activities were decreased. Besides, the GPx, GR, GST, and GSH activities were decreased. Histological alterations in kidney tissue and intense apoptosis in renal tubular cells were observed. These results suggest that DDT sub-acute treatment causes oxidative stress and apoptosis, which may be the chief mechanisms of DDT-induced nephrotoxicity.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 309-320.

  Gastroprotective effect of ghrelin against indomethacin-induced gastric injury in rats: possible role of heme oxygenase-1 pathway
Mona Allam 1), Ola El-Gohary

1)Department of Physiology, Faculty of Medicine, Benha University, Benha, Egypt.

Ghrelin has been shown to ameliorate gastric injury by several mechanisms in experimental animal models. The present study aimed to investigate the effect of pretreatment with ghrelin on indomethacin-induced gastric injury in rats and the role of heme oxygenase-1(HO-1) pathway as a novel mechanism underlying the gastroprotective effect of ghrelin. In all groups studied, ulcer score (U.S), ulcer index (U.I) and preventive index (P.I) were evaluated and the gastric inflammatory biomarkers including levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and myeloperoxidase (MPO) activity as well as prostaglandin E2 (PGE2), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), HO-1 and bilirubin as an indicator of heme oxygenase activity were measured. Indomethacin induced significant elevation in U.S and U.I as well as the inflammatory and the oxidative markers and reduced the PGE2 in addition to HO-1 level and activity. Pretreatment with ghrelin reversed these results. In order to elucidate the possible role of HO-1 in mediating the protective effects of ghrelin, tin protoporphyrin (SnPP) HO-1 blocker was administrated; it significantly attenuated the gastroprotective effect of ghrelin. In conclusion HO-1 activity significantly contributes toward ghrelin-mediated gastroprotection.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 321-330.

  Chemical components, antioxidant potential and hepatoprotective effects of Artemisia campestris essential oil against deltamethrin-induced genotoxicity and oxidative damage in rats
Mongi Saoudi 1), Marwa Ncir, Manel Ben Ali, Malek Grati, Kamel Jamoussi, Noureddine Allouche, Abdelfattah El Feki

1)Laboratory of Animal Ecophysiology, Sciences Faculty, University of Sfax, Sfax, Tunisia.

In the present study, we evaluated the antioxidant potential of Artemisia campestris essential oil (ACEO) and the possible protective effects against deltamethrin induced hepatic toxic effects. The ACEO showed radical scavenging activity with IC50 = 47.66 ± 2.51 µg/ml, ferric reducing antioxidant power (FRAP) potential (EC50 = 5.36 ± 0.77 µg/ml), superoxide scavenging activity (IC50 = 0.175 ± 0.007 µg/ml) and ˙OH scavenging activity (IC50 = 0.034 ± 0.007 µg/ml). The obtained results of phenolic profile demonstrated that phenolic compounds are the major contributor to the antioxidant activity of ACEO. GC–MS analysis revealed the presence of 61 components in which monoterpene hydrocarbons constitute the major fraction (38.85%). In in vivo study, deltamethrin exposure caused an increase of serum AST, ALT and ALP activities, hepatic malondialdehyde (MDA) (measured as TBARS) and conjugated dienes markers of lipid peroxidation (LPO), while antioxidant enzyme activities (SOD, CAT and GPx) decreased significantly. Furthermore, it induces DNA damage as indicated by DNA fragmentation accompanied with severe histological changes in the liver tissues. The treatment with vitamin E or ACEO significantly improved the hepatic toxicity induced by deltamethrin. It can be concluded that vitamin E and ACEO are able to improve the hepatic oxidative damage induced by deltamethrin. Therefore, ACEO is an important product in reducing the toxic effects of deltamethrin.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 331-342.

  Modulatory effects of naringin on hepatic key enzymes of carbohydrate metabolism in high-fat diet/low-dose streptozotocin-induced diabetes in rats
Leelavinothan Pari 1), Ramasamy Chandramohan

1)Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalai Nagar-608002, Tamil Nadu, India.

We evaluated the modulatory effects of naringin on altered hepatic key enzymes of carbohydrate metabolism in high-fat diet/low-dose streptozotocin-induced diabetic rats. Oral treatment of naringin at a doses of 20, 40 and 80 mg/kg body weight to diabetic rats for 30 days resulted in a significant reduction in the levels of plasma glucose, blood glycosylated hemoglobin and increase in the levels of plasma insulin and blood hemoglobin. The altered activities of the hepatic key enzymes of carbohydrate metabolism such as hexokinase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, glucose-6-phosphate dehydrogenase, glycogen synthase, glycogen phosphorylase and glycogen content of diabetic rats were significantly reverted to near normal levels by the treatment of naringin in a dose-dependent manner. Naringin at a dose of 80 mg/kg body weight showed the highest significant effect than the other two doses (20 and 40 mg/kg). Further, immunohistochemical observation of pancreas revealed that naringin-treated diabetic rats showed the increased number of insulin immunoreactive β-cells, which confirmed the biochemical findings. These findings revealed that naringin has potential antihyperglycemic activity in high-fat diet/low-dose streptozotocin-induced diabetic rats.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 343-352.

  Consequences of lipopolysaccharide and n-3 polyunsaturated fatty acid administration on aortic function of spontaneously hypertensive rats
Barbara Kaprinay 1), Ruzena Sotnikova, Karel Frimmel, Jakub Krizak, Iveta Bernatova, Jana Navarova, Ludmila Okruhlicova

1)Institute of Experimental Pharmacology and Toxicology, Slovak Academy of Sciences, 841 04 Bratislava, Slovakia.

The aim of the work was to study the delayed effect of lipopolysaccharide (LPS) administration on endothelial function of the aorta of rats with genetic hypertension. Further, the possibility to ameliorate LPS-induced changes by n-3 polyunsaturated fatty acids (n-3 PUFA) was tested. Rats received a bolus of 1 mg/kg LPS i.p.; n-3 PUFA were administered in the dose of 30 mg/kg daily for 10 days p.o.. Ten days after receiving of LPS, the body weight gain of rats was statistically lower compared to control rats (p < 0.05). n-3 PUFA administration to LPS rats had no effect on this parameter. The TBARS and NAGA concentrations in plasma were significantly increased in the LPS group (p < 0.05) and n-3 PUFA administration returned them to control values. In functional studies, phenylephrine (PE, 1 µmol/l) evoked contraction of aortas which was not statistically different among experimental groups. However, endothelium-dependent relaxation was depressed in the LPS group (p < 0.05) and n-3 PUFA slightly recovered it to control values. In conclusion, oxidative stress seems to be responsible for aortic endothelial dysfunction detected 10 days after administration of LPS to rats. n-3 PUFA slightly improved the function of the endothelium injured by LPS, probably thanks to their antioxidant properties. Prolonged administration of higher doses of n-3 PUFA should defend the vascular endothelium against detrimental effect of bacterial inflammation.

General Physiology and Biophysics. Volume 36, 2017, No. 3: 353-359.