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Biomedical subjects

A Agar

Publications and source records attributed to A Agar.

16 recordsLinked to original sources
PubMed2004

Effects of N-nitro l-arginine methyl ester (l-NAME), a potent nitric oxide synthase inhibitor, on visual evoked potentials of rats exposed to different experimental stress models.

AIM: The aim of our study was to investigate the effects of the nitric oxide synthase inhibitor, N-nitro l-arginine methyl ester (l-NAME, 10 mg kg-1 day-1 i.p.), on visual evoked potentials (VEPs) and lipid peroxidation expected to occur during chronic stress (15 days). METHODS: Eight experimental groups, each consisting of 10 rats, were formed: control group (C), the group injected with l-NAME (L), groups exposed to cold stress (CS), immobilization stress (IS), and both cold and immobilization stress (CIS), groups exposed to stress and injected with l-NAME (CSL, ISL, CISL). RESULTS: l-NAME decreased brain and retina nitrite levels in all experimental groups compared with their corresponding control groups. l-NAME decreased glutathione peroxidase (GSH-Px) activity in the brain and retina in the L group, but increased it in the CSL and CISL groups compared with the C group. Lipid peroxidation was increased in the brain and retina tissues of all stress groups with respect to the C group. l-NAME markedly increased brain thiobarbituric acid reactive substances (TBARS) levels in the L group, while significantly decreasing brain and retina TBARS levels in all stress groups in comparison with their respective control groups. l-NAME caused a significant delay in all components of VEPs in the L group compared with the C group. However, l-NAME significantly decreased latencies of P1, N1, P2 and P3 components in the CSL group and all components in the ISL and CISL groups with respect to their corresponding control groups. CONCLUSION: This study clearly indicated that lipid peroxidation may be one possible factor affecting VEP components.

Animals↗
PubMed2003

Training induced alterations of visual evoked potentials are not related to body temperature.

The purpose of this study was to investigate the effect of mild chronic exercise on visual evoked potentials (VEPs). Twenty male Wistar rats were randomly divided into two groups: Control (C) and Exercise (E) groups. Exercise was performed on a motor-driven treadmill for 8 weeks. After 5 min of exercise, plasma lactic acid levels were determined. At the end of the experimental period, VEPs were recorded from E group twice: Five min (E-5 min) and 24 h (E-24 h) after the last bout of exercise. During visual evoked potential (VEP) recordings body temperature of the animals was kept constant to eliminate the effect of temperature changes. No difference was found between the lactic acid levels of two groups. The mean latencies of VEPs from E-5 min were shortened compared with the control group. The mean latencies of VEP components in E-24 h were observed to have returned to the control levels. Peak to peak amplitudes of VEPs were found to be unaltered among all measurements. We concluded that immediately after exercise, VEPs latencies were shortened independently from body temperature via unknown mechanisms. The latencies of VEPs were returned to control values after 24 h.

Analysis of Variance↗
PubMed2002

The effect of exercise on brain antioxidant status of diabetic rats.

BACKGROUND: To investigate the effect of exercise on brain antioxidant status of diabetic rats. METHODS: Wistar rats were divided into four groups: Control (C), exercise (CE), diabetic (D), and diabetic+exercise (DE). Diabetes was induced by single administration of streptozotocin (60 mg/kg). We used an aerobic exercise program for 8 weeks of CE and DE rats. After the end of the experimental period, Cu, Zn-superoxide dismutase (Cu, Zn-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), xanthine dehydrogenase (XDH) and xanthine oxidase (XO) activities and thiobarbituric acid reactive substances (TBARS) levels of brain were measured. RESULTS: Diabetes caused significant reduction of brain Cu, Zn-SOD and GSH-Px activities in the D and DE groups. CAT activity was decreased only in the D group. Exercise did not alter CAT activity of brain, whereas markedly increased Cu, Zn-SOD activity in the DE group. In contrast to diabetes-related decrease in the activity of Cu, Zn-SOD, increase in the XO and GSH-Px activities were observed in the DE group compared with the D group. XDH activity was significantly reduced in two exercise groups according to the control rats, but the decrease was not accompanied with the activity of XO elevation in all groups. Increase in the XO activity and decrease in the XDH activity in the DE rats have revealed that diabetes and exercise have potentially effect in free radical production. On the other hand, TBARS levels were found to be elevated in all diabetic animals. CONCLUSIONS: Our results show that aerobic exercise did not affect lipid peroxidation of brain, but in diabetic condition improved antioxidant defence.

Animals↗
PubMed2001

Identification of Anopheles aquasalis as a possible vector of malaria in Guyana, South America.

Adult female mosquitoes were collected in Mahdia, Guyana, to determine the incidence of malaria in Anopheles species found during the month of June 2000. Centers for Disease Control miniature white (incandescent) light traps, model 512, and miniature black (ultraviolet) light traps, model 912, were used to capture female mosquitoes. Numbers of mosquitoes collected were compared between white and black light traps and between traps set outside and inside of buildings. Adult female Anopheles mosquitoes were identified and an ELISA dipstick test for Plasmodium vivax and Plasmodium falciparum was performed on each mosquito. An aquasalis, An oswaldoi, and An braziliensis were attracted to white light traps. An triannulatus and An darlingi were collected from black light traps. Approximately the same numbers of all female Anopheles mosquitoes 28/45 (62%) were caught inside buildings as outside. Numbers of female non-anopheles mosquitoes captured in light traps varied between the traps set outside of buildings and inside of buildings with bright light traps collecting 91/122 (75%). A total of 45 Anopheles mosquitoes were captured and 122 non-anopheles species. Of the two known vectors of malaria in Guyana, An darlingi mosquitoes were not infected with P vivax but An aquasalis was found to be a carrier. The findings of this study suggest a need for further surveying and identification of current malaria vectors in Guyana.

Animals↗
PubMed2000

Pressure related apoptosis in neuronal cell lines.

Pressure is a crucial component of the cellular environment, and can lead to pathology if it varies beyond its normal range. The increased intra-ocular pressures in acute glaucoma are associated with the loss of neurons by apoptosis. Little is known regarding the interaction between pressure and apoptosis at the level of the cell. The model developed in this study examines the effects of elevated ambient hydrostatic pressure directly upon cultured neuronal lines. Conditions were selected to be within physiological limits: 100 mmHg over and above atmospheric pressure for a period of 2 hr, as seen clinically in acute glaucoma. This system can be used to investigate pressure relatively independently of other variables. Neuronal cell line cultures (B35 and PC12) were subjected to pressure conditions in specially designed pressure chambers. Controls were treated identically, except for the application of pressure, and positive controls were treated with a known apoptotic stimulus. Apoptosis was detected by cell morphology changes and by 2 specific apoptotic markers: TUNEL (Terminal transferase dUTP Nick-End Labeling) and Annexin V. These fluorescent markers were detected and quantified by automated Laser Scanning Cytometry. All techniques showed that increased pressure was associated with a greater level of apoptosis compared to equivalent controls. Our results suggest that pressure alone may act as a stimulus for apoptosis in neuronal cell cultures. This raises the possibility of a more direct relationship at the cellular level between pressure and neuronal loss.

Acute Disease↗
PubMed2000

The effect of pre and postnatal cadmium exposure on somatosensory evoked potentials: relation to lipid peroxidation.

Pregnant swiss albino rats were divided into three groups: control (C), gestational exposure of cadmium (G-Cd) and gestational/postnatal exposure of cadmium (GP-Cd) groups. Control animals received tap water and the rats of GP-Cd group received Cd as CdCl2 in their drinking water during the experimental period. G-Cd group was given Cd during pregnancy, but given tap water after birth. Twenty-two days after birth, 15 rats (for each group) were taken from their mothers and continued to be treated with Cd (GP-Cd group) or tap water (C and G-Cd groups) for an additional 38 days. On postnatal day (PND) 60, somatosensory evoked potentials (SEPS) of three groups were recorded following left posterior tibial nerve (PTN) stimulation. The mean latencies of N1, P1, and N2, components were significantly prolonged in both Cd groups compared with control group. The mean latency of N1 in the GP-Cd group was longer than control and the G-Cd groups. There was no significant amplitude differences among groups. On the other hand, thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation, were increased in the sciatic nerves of both groups compared with control group. A significant increase in the TBARS level of the brain was found only in GP-Cd group due to significant accumulation of Cd.

Age Factors↗
PubMed2000

Effect of sulfur dioxide inhalation on erythrocyte antioxidant status and lipid peroxidation in experimental diabetes.

The effect of sulfur dioxide (SO(2) ) on red cell antioxidant status and lipid peroxidation was examined in this research. Forty healthy male albino rats, aged three months, were divided into four equal groups: Control (C), SO(2) +C (CSO(2) ), diabetic (D) and SO(2) +D (DSO(2) ). Experimental diabetes mellitus was induced by i.v injection of alloxan with a dose of 50 mg/kg body weight. Ten ppm SO(2) was administered to the animals of SO(2) exposed groups in an exposure chamber for one hr/day x 7 days/wk x 6wks while other groups were exposed to filtered air in the same condition. SO(2) exposure, while markedly decreasing Cu, Zn-Superoxide dismutase (Cu, Zn-SOD) activity, significantly increased glutathione peroxidase (GSH-Px), catalase (CAT), glutathione (GSH) and glutathione-s-transferase (GST) activities and TBARS values in CSO(2) and DSO(2) groups compared with their respective control groups. From these results, it could be concluded that adaptative changes occurred in antioxidant systems that may counteract the free radical effect of SO(2) in the experimental groups.

Alloxan↗
PubMed1998

The effects of cadmium and experimental diabetes on VEP spectral data and lipid peroxidation.

Fifty-two healthy swiss male albino rats, aged three months were used in this study. They were divided into four groups: Control (C), diabetic (D), Cadmium (Cd) and diabetic + Cadmium (D + Cd) groups. Diabetic condition was induced in D and D + Cd groups by administration of alloxane (5 mg/100 g). After this treatment, Cd and D + Cd groups were injected with CdCl2 i.p. (2 mg/kg/week). At the end of the two months of experimental period, flash visual evoked potentials (FVEPs) of four groups were recorded and amplitude spectral analysis was computed by transient response-frequency characteristics (TRFC) method. Significant amplitude decrement was found in 2-4 Hz frequency band of D + Cd group in comparison with C group. On the other hand, our data showed that Cd treatment and diabetic condition caused a significant increase of lipid peroxidation in kidney, brain, retina and lens.

Analysis of Variance↗
PubMed1996

Cadmium induced alterations in somatosensory evoked potentials.

Pregnant Swiss albino rats were divided into three groups: control (C), cadmium (Cd) and non-cadmium (NCd) groups. Control animals received tap water; the Cd rats received Cd as CdCl2 in their drinking water during the experimental period, while the NCd group was given Cd during pregnancy, and given tap water after birth. Twenty-two days after birth, 15 rats (for each group) were taken from their mothers and continued to be treated with Cd (Cd group) or tap water (C and NCd groups) for an additional 38 days. After the treatment period, somatosensory evoked potentials (SEPs) of the three groups were recorded from central (Cz) referenced to frontal (Fz) following left posterior tibial nerve (PTN) stimulation. Amplitude spectra of SEPs were computed by fast Fourier transform (FFT) algorithm. There was a significant amplitude decrease in 1-3.5 Hz in the NCd group and 1-3.5 and 14-20 Hz frequency bands of the Cd group compared with the control group.

Analysis of Variance↗
PubMed1996

Effect of chronic cadmium exposure on VEP and EEG spectral components.

Pregnant swiss albino rats were divided to three groups as control (C), cadmium (Cd) and non-cadmium (NCd) groups. Control animals were received tap water while the rats of Cd group were received Cd as CdC12 in their drinking water during the experimental period. On the other hand, the NCd group was given Cd during pregnancy, but given tap water after birth. Twenty-two days after birth, fourteen rats (for each group) were taken from their mothers and continued to be treated with Cd (Cd group) or tap water (C and NCd groups) for an additional 38 days. After the experimental period, flash VEPs and EEGs of three groups were recorded and amplitude spectral analysis was computed by Transient Response-Frequency characteristics (TRFC) method. The mean amplitude (dB) of 1-3.5 and 14-20 Hz frequency bands for right response whereas 1-3.5, 4-7, 8-13 and 14-20 Hz frequency bands for left response of VEPs were decreased in Cd group compared with control group. On the other hand, significant differences were observed between Cd and control groups in all the frequency bands of EEGs except 6-8 Hz.

Administration, Oral↗
PubMed1995

ERP spectral analysis of cholesterol rich patients.

Visual event-related potentials (ERPs) were studied in twenty hypercholesterolemic (HC) patients and twenty age-matched healthy controls. ERPs were recorded in two different experimental conditions that the target stimulus (red light) was counted (Test 1) or uncounted (Test 2). Amplitude spectra of ERPs were computed by transient response-frequency characteristics (TRFC) method. Their maxima were found to occupy the frequency bands of 1-2, 3-4, 5-7, 8-12, 13-20, 20.5-32 Hz. The amplitude mean (decibel) of 1-2 and 3-4 frequency bands were decreased in Test 2 compared to Test 1 in the control group, but no significant amplitude differences were found between Test 1 and Test 2 in the HC group.

Adult↗
PubMed1995

Event-related potentials in hypertriglyceridemia.

Event-related potentials (ERPs) of twenty-three hypertriglyceridemic (HTG) patients and twenty-three age-matched healthy controls were recorded in two different experimental conditions that the target stimulus was counted (Test 1) or uncounted (Test 2). Latencies of each wave were inside normal limits in all patients. No differences were found in the P3b amplitudes of Test 1 case among HTG and control subjects. Amplitude spectra of ERPs were computed by transient response-frequency characteristics (TRFC) method. Their maxima were found to occupy the frequency bands of 1-2, 3-4, 5-7, 8-12, 13-20, 20.5-32 Hz. When comparing Test 1 with Test 2, significant amplitude differences were found in 1-2 and 3-4 frequency bands of controls and 1-2 and 13-20 frequency bands of patient group.

Adult↗
PubMed1995

The effect of aging on spectral parameters of event-related potentials.

Forty-two healthy subjects ranging in age from 20 to 73 were divided into three groups according to age; a young group (20-33 years), a middle-aged group (34-49 years) and older group (50-73 years). Event-related potentials (ERPs) of three groups were recorded in two different experimental conditions that the infrequent stimulus was counted (Test 1) or uncounted (Test 2). ERPs were elicited using infrequent and frequent stimuli as red and green lights respectively. Spectral analysis of ERPs showed that decibel (dB) values of 1-2 and 3-4 Hz in young and middle-aged groups while dB value of 1-2 Hz in older group were significantly decreased in Test 2 compared with Test 1. When the number of subjects displaying amplitude maximum in each frequency band was considered, significant differences were found in 1-2 and 5-7 Hz frequency bands of young and middle-aged groups, but no significant differences were found for older group.

Adult↗
PubMed1993

Spectral analysis of event related potentials.

Event-related brain potentials (ERPs) of twenty normal subjects with no sign of neurologic diseases were measured by applying nontarget and target stimuli as green and red lights respectively. ERPs were recorded in two experimental conditions that the target stimulus was counted (Test 1) or uncounted (Test 2). The spectral analysis of ERPs recorded for Test 1 and Test 2 were computed by using the Transient Responses Frequency Characteristics (TRFC) method. Amplitude maxima were observed in the frequency bands as indicated: 1-2, 3-4, 5-6, 7-8, 8-12, 13-20, 20.5-36, 36 Hz and higher. When we compared Test 2 with the results of Test 1, we observed a significant decrease in the amplitude mean (decibel) of 1-2 Hz frequency band (p < .05). Repeated measures ANOVAs also showed that dB values of 1-2 Hz between counted and uncounted stimuli were significantly different (p < .04). When the number of subjects displaying amplitude maximum in each frequency band was considered, we have found important differences in 1-2, 3-4 Hz and 5-6 Hz bands.

Adult↗
PubMed1993

The immunology of scabies.

Individuals with scabies react to bites by generating a cell-mediated immune response at the bite site. This elicits a very itchy papule that is often excoriated. Sometimes ulcerated papules, vasculitis, and nodules develop as a result of other immunologic reactions in skin. Immunologic reactions mediated by antibodies of the immunoglobulin G (IgG), IgM, and especially, IgE classes may also be involved. None of these reactions have been shown to eliminate all mites from the skin surface, but locally these reactions may prevent the epidemic multiplication of scabies' organisms on the skin surface, as observed in some patients with crusted scabies.

Acquired Immunodeficiency Syndrome↗