Recai Ogur

Melatonin as an antibiotic: new insights into the actions of this ubiquitous molecule

Abstract:  The incidence of serious infections caused by multidrug‐resistant gram‐positive and gram‐negative bacteria has been increasing rapidly worldwide despite advances in antibacterial therapy in the last two decades. Among multidrug‐resistant gram‐positive and gram‐negative bacteria, methicillin‐resistant Staphylococcus aureus, carbapenem‐resistant Pseudomonas aeruginosa and Acinetobacter baumannii are of great importance, because they have emerged as primary nosocomial pathogens in hospital outbreaks. In this study, we investigated whether melatonin has antibacterial effects against these microorganisms in vitro. The minimum inhibitory concentration of melatonin was determined using a standard microdilution method at 24 and 48 hr. Melatonin inhibited microbial growth at both 24 and 48 hr; but results showed that melatonin had antibacterial effects against these microorganisms after 48 hr of incubation in lower doses [concentrations between 31.25 to 125 μg/mL (0.13–0.53 mm)]. Also, it was determined that melatonin has a more potent antimicrobial effect on gram‐negative microorganism. Among possible mechanisms, it is concluded that melatonin showed antibacterial effects by reducing intracellular substrates.

High nitrate intake impairs liver functions and morphology in rats; protective effects of α-tocopherol.

The aim of this study was to determine the effect of high dose nitrate ingested in drinking water, on liver enzymes and histopathology, liver weight/body weight (lw/bw) ratio, serum and liver malondialdehyde (MDA) levels and osmotic fragility in Sprague-Dawley rats. These parameters were compared on 40 rats divided into four groups; control animals (group A) drank filtered tap water containing maximum 10mg/L nitrate while treatment groups drank 200mg/L (group B), 400mg/L (group C) and α-tocopherol plus 400mg/L (group D) nitrate containing water ad libitum for 60 days. As a result, lw/bw ratio increased significantly (p<0.05) among rats that consumed water with 400mg/L nitrate. Osmotic fragility increased significantly in treatment groups (p<0.05 versus control). Liver but not serum MDA levels increased in group C (p<0.05 versus control). Group A showed normal hepatic lobular architecture and histology. After nitrate administration, there was hepatocellular degeneration with increased intercellular space of the liver cells in groups B and C. Liver MDA, osmotic fragility and liver histology have returned to nearly normal in group D. These findings show clearly that high nitrate ingestion can cause pathological changes in liver histology and functions. Moreover, α-tocopherol can prevent these effects, possibly through antioxidant properties.

Establishing the use of melatonin as an adjuvant therapeutic against paraquat- induced lung toxicity in rats

It is well known that the intake of paraquat (PQ) causes severe tissue injury leading to numerous fatalities. Considering that the main target for PQ toxicity is the lung and involves the production of reactive oxygen and nitrogen species, transcription factors and inflammatory cytokines, it may be hypothesized that the combination of a potent antiinflammatory and antioxidant agent may counteract more of PQ’s effects than an antiinflammatory agent alone. For this purpose, combination of dexamethasone (Dex) and melatonin (Mel) was compared with Dex alone. A total of 40 male Wistar albino rats were divided into four groups as control, PQ, Dex only, and Dex plus Mel. The animals were given intraperitoneally a toxic dose of 19 mg/kg PQ dissolved in 1 ml saline. Control animals were injected with the same amount of saline only. A dose of 1 mg/kg Dex was administered 2 hrs after PQ administration. In the combination treatment group, 20 mg/kg Mel was given with Dex. All drugs were given every 12 hrs for a total of six doses. Five animals in PQ group and three animals in Dex only group died by the end of the study. No deaths occurred in the Dex+Mel group. Dex exerted improvements in several oxidative and antioxidative parameters. However, combination treatment provided beneficial effects against PQ toxicity far greater than Dex alone. This difference was also apparent when tissues were histologically compared. In conclusion, Mel exhibited strong additive beneficial effects with Dex and can be considered as a safe treatment modality against PQ toxicity.

Blood pressure changes in young male subjects exposed to a median altitude

ObjectiveResidence at high altitude has been associated with elevation in systemic blood pressure (BP), but few studies have been done on the time course and the effects of a median altitude. Moreover, there exist population differences in the reactions given to altitude and the mechanism is unknown. This study was therefore designed to determine the effects of a median altitude on resting BP and heart rate (HR) in a group of 15 healthy, young, Turkish male subjects.MethodsAfter basic measurements were carried out in Bursa (155 m), subjects were transported to a mountain hotel (altitude 1,860 m), where the measurements were repeated once every 15 days during a 10-month period.ResultsMean BP and diastolic BP increased on Day 4 and then remained above first values throughout the study. Compared with control measurements, high altitude increased systolic blood pressure (SBP) in all subjects, but in Month 4 and Month 6, SBP returned to control values, and remained elevated thereafter. HR continued to decrease in parallel with time and significant decrease occurred after Month 5.InterpretationOur findings imply that moderate-altitude living results in a significantly greater BP and lower HR over equivalent low-altitude measurements and we conclude that chronic exposure to hypobaric hypoxia at a median altitude causes increased parasympathetic and sympathetic tone in healthy, young, Turkish males.

How Medical Students Use the Computer and Internet at a Turkish Military Medical School

The aim of this study was to determine how medical students use the computer and World Wide Web at a Turkish military medical school and to discuss characteristics related to this computer use. The study was conducted in 2003 in the Department of Public Health at the Gulhane Military Medical School in Ankara, Turkey. A survey developed by the authors was distributed to 508 students, after pretest. Responses were analyzed statistically by using a computer. Most of the students (86.4%) could access a computer and the Internet and all of the computers that were used by students had Internet connections, and a small group (8.9%) had owned their own computers. One-half of the students use notes provided by attending stuff and textbooks as assistant resources for their studies. The most common usage of computers was connecting to the Internet (91.9%), and the most common use of the Internet was e-mail communication (81.6%). The most preferred site category for daily visit was newspaper sites (62.8%). Approximately 44.1% of students visited medical sites when they were surfing. Also, there was a negative correlation between school performance and the time spent for computer and Internet use (-0.056 and -0.034, respectively). It was observed that medical students used the computer and Internet essentially for nonmedical purposes. To encourage students to use the computer and Internet for medical purposes, tutors should use the computer and Internet during their teaching activities, and software companies should produce assistant applications for medical students. Also, medical schools should build interactive World Wide Web sites, e-mail groups, discussion boards, and study areas for medical students.

Effects of high nitrate intake in rats.

The purpose of this study was to determine the effects of administration of high dose nitrate in drinking water on weight gain, hematological parameters and osmotic fragility in rats. We compared these parameters in 40 rats divided into four groups (one control and three treatment groups). Control animals drank filtered tap water containing a maximum of 10 mg/l nitrate while the treatment groups drank 100 mg/l, 200 mg/l and 400 mg/l nitrate-containing water ad libitum for 60 days. Animals in the treatment groups gained less weight than the control group and the differences between the control and treatment groups were statistically significant (p < 0.05). At the concentration of 100 mg/l nitrate, platelet counts and hemoglobin levels were significantly increased compared with the control group (p < 0.05). At the concentration of 200 mg/l nitrate, erythrocyte counts, hemoglobin and hematocrit levels were significantly increased compared with the control group (p < 0.05). At the concentration of 400 mg/l nitrate, platelet counts were decreased significantly when compared with the first two treatment groups (p < 0.05). There were statistically significant differences in osmotic fragility ratios between treatment groups and the control group (p < 0.05). We concluded that high nitrate intake in drinking water decreases weight gain, affects hematological parameters by inducing bone marrow activity at low doses and inhibiting it at high doses, and increases erythrocyte osmotic fragility.

The Effects of Medical Ozone Therapy on Renal Ischemia/Reperfusion Injury

Introduction: This study was designed to investigate the possible beneficial effects of medical ozone therapy (OT), known as an immunomodulator and antioxidant, on the renal function, morphology, and biochemical parameters of oxidative stress in kidneys subjected to ischemia/reperfusion injury (IRI). Materials and methods: Thirty male Sprague–Dawley rats were classified into three groups: control, renal IRI, and renal IRI + OT. The IRI group was induced by bilateral renal ischemia for 60 min, followed by reperfusion for 6 h. After reperfusion, the kidneys and blood of rats were obtained for histopathologic and biochemical evaluation. Results: Renal IRI increased the tissue oxidative stress parameters (lipid peroxidation, protein oxidation, and nitrite plus nitrate) and decreased the antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase). The serum neopterin levels showed correlation with oxidative stress parameters. All these parameters were brought to control values in the treatment group. Histopathologically, the kidney injury in the treatment group was significantly lesser than in the renal IRI group. Conclusions: Our results clearly showed that OT has beneficial effect to protect kidney against IRI. The serum neopterin levels might be used as a marker to detect the degree of renal IRI.

A Commonly Used Pesticide Endosulfan in Diet Could Cause Hepatomegaly and Kidney Tumor When Combined with Nitrosamines

Pesticides and nitrites which could be available in foods are generally investigated individually, although they could be found in foods together and exhibit combined health effects. In this study we aimed to determine the combined effects of endosulfan which is a commonly used pesticide and N-nitroso-N-methylurea (NMU) which is a prototype for mammary tumor development in Sprague Dawley rats and could be formed in brine foods or also in body from nitrites which is commonly used in meat. Ninety female Sprague Dawley rats had been used. Animals were divided three groups which consisted 30 animals. The first group took a single dose endosulfan intraperitoneal (ip) on 19th day and a single dose NMU ip on 21 day, the second group took endosulfan by their drinking waters for the first 60 days of their life and a single dose NMU ip on 21 day, and the third group took only a single dose NMU ip on 21 day. Animals were controlled for their general health status, mammary mass develeopment, daily water consumption and weekly weight gain. At the end of the study rats were examinated carefully under anesthesia, and tissue samples were prepared from their mammary glands and intraabdominal organs. Tissue samples taken from mammary glands, liver and kidneys were histopathalogically examined. It was determined a statistically significant hepatomegally in the second group when we compared to other groups (p < 0.05). No animals developed mammary tumors. On the macroscopic examination and manual palpation of intraabdominal region, it was showed that solid tumors in kidneys as a ratio of 76.7% of the animals in the second group (bilateral in 1,3% of them, the others are unilaterally and 70% of the unilateral tumors are in the left kidneys while the rest of them are right localized). Also it was found that in the first group, 13.4% of the animals developed unilateral kidney tumors. The third group which had been applied only NMU developed no kidney or liver pathalogy macroscopically. As a result it was considered that a diversity which is named as “genetic shift” could be developed in our animal research center and because of this shift we could not developed NMU induced mammary tumors in our Sprague Dawley rats. But it has been showed that long term endosulfan expose has resulted in kidney tumor development for the first time. Because of the genetic shifting mentioned above, it should be tested whether this experimental animal cancer model is limited for our research center or not by obtaining sprague dawley animals from different centers. Interactions of living style, environmental factors and genetic properties in the development of cancer and its necessary to control all of three factors in order to reduce cancer frequency in public showed that the importance of interdiciplinary collaboration and public education. Consumers and appliers should be educated about using pestices, and healthy and safety food production and concumption should be considered as one of the primary subjects in public health studies.

Evaluation of some physical hazards which may affect health in primary schools

AIM This study was performed with the objective to determine the levels of some physical hazards in primary schools. MATERIAL AND METHODS This study is a cross-sectional field survey. In this study which was conducted in 31 primary schools selected by appropriate sampling from the district of Keçiören of the province of Ankara, measurements related with temperature, light, electromagnetic field (EMF) and noise levels were done at hundreds of points. Approval was obtained from Gülhane Military Medical Faculty Ethics Committee (2007/97). RESULTS Only 47.1% of the classes had a temperature value within the recommended limits (20-21°C). It was found that the illumination levels in 96.8% of the schools were above the standard values. However, the levels of illumination were found to be statistically significantly decreased towards the door and the back line (p<0.05). It was found that electromagnetic field levels were significantly higher in the schools who had a source of electromagnetic field nearby compared to the schools who did not have such a source nearby (p<0.001). It was found that the electromagnetic field levels in computer classes were statistically significantly higher compared to the other classes (p<0.001). Noise levels were found to be statistically significantly higher in classes which had 35 and more students (p<0.05). No statistically significant difference was found in schools near intensive vehicle traffic in terms of noise levels (62.8±5.0 (n=72), 62.0±6.4 (n=79), respectively, p>0.05). CONCLUSIONS It was found that primary schools in the region of Keçiören had aspects which had to be improved in terms of building age, building location, brightness, electromagnetic field and noise levels. School health programs directed to improve negative enviromental factors should be developed.

Effects of the menstrual cycle on injection pain due to rocuronium

STUDY OBJECTIVE To investigate the effect of the menstrual cycle on rocuronium injection pain. DESIGN Prospective, randomized, double-blinded study. SETTING Academic medical center. PATIENTS 80 ASA physical status 1 and 2 women scheduled for elective surgery with general anesthesia. MEASUREMENTS Patients were divided into two groups according to their time in the menstrual cycle. Forty patients at days 8 to 12 of the menstrual cycle were considered to be at the follicular phase (Group F), and 40 patients at days 20 to 24 of the menstrual cycle were considered to be at the luteal phase (Group L).Withdrawal movements were recorded. MAIN RESULTS Overall frequency of withdrawal movements was significantly higher in Group L than Group F (P < 0.001). The mean withdrawal movement score was 1.77 ± 0.76 in Group L and 0.52 ± 0.67 in Group F. CONCLUSION Menstrual cycle phases affect the severity of rocuronium injection pain. Women exhibit greater pain sensitivity from rocuronium injection in the luteal phase than the follicular phase.