Dikmen Dokmeci

A comparison of the effect on gastric emptying of propofol or dexmedetomidine in critically ill patients: preliminary study.

Background: Propofol and dexmedetomidine are widely used for sedation in the intensive care unit yet there are limited data on its effects on gastric motility. In our preliminary study, we examined whether or not any effect of propofol and dexmedetomidine on gastric emptying is preserved in critically ill patients. Methods: Twenty‐four critically ill, enterally fed adult patients each received enteral feeding via a nasogastric tube at 50 mL h−1 throughout the 5‐h study period. Either propofol 2 mg kg−1 h−1 (n = 12, Group P) or dexmedetomidine 0.2 μg kg−1 h− (n = 12, Group D) was given intravenously over 5 h. Gastric motility was measured indirectly by analysis of the absorption over time of 1.5 g of paracetamol administered into the stomach at the start of the study period. At the beginning and end of the study, residual gastric volume and pH of residual gastric fluid were measured. Results: Gastric residual volume measured at the end of propofol infusion (19.33 ± 11.33) was found to be higher when compared with the volume measured before infusion (11.33 ± 4.84) and after dexmedetomidine infusion (9.17 ± 4.54). But, there was no difference between groups in gastric emptying time (AUC120 894.53 ± 499.39 vs. 1113.46 ± 598.09 propofol and dexmedetomidine groups, respectively). Conclusion: In our study, gastric residual volume measured at the end of propofol infusion was found to be higher when compared with the volume measured before infusion and after dexmedetomidine infusion. There was no difference between groups in gastric emptying time.

Involvement of NMDA receptors and nitric oxide in the thermoregulatory effect of morphine in mice.

Summary. Morphine has long been known to have potent effects on body temperature. It has been suggested that both N-methyl-D-aspartate (NMDA) receptors and nitric oxide (NO) pathway are involved in thermoregulation and also known to play important roles in some of morphine effects. The aim of this study was therefore to investigate the contribution of NMDA receptors and NO to the thermoregulatory effect of morphine. Morphine produced a hypothermic effect, especially at the dose of 10 mg/kg. Ketamine (5–40 mg/kg, i.p.) and NG-nitro-L-arginine-methyl ester (L-NAME, 1–100 mg/kg, i.p.) also produced hypothermic effects with their higher doses. At doses which themselves produced no effect on colonic temperature in mice, both ketamine (10 mg/kg, i.p.) and L-NAME (10 mg/kg, i.p.) enhanced the hypothermic effect of morphine (10 mg/kg, i.p.). These results further support the relationship between NO and NMDA receptors and suggest a possible role of NMDA-NO pathway in the thermoregulatory effect of morphine.

The role of histamine H1 receptors in the thermoregulatory effect of morphine in mice

Morphine is known to release histamine from mast cells and increase the turnover of neuronal histamine. It is also known that histamine receptors mediate some of the morphine effects. The contribution of histamine H1 and H2 receptors to the thermoregulatory effect of morphine in mice was investigated in the present experiments. Morphine produced a hypothermic effect, especially at the dose of 10 mg/kg. Although the histamine H1 receptor antagonist, dimethindene (0.1 mg/kg, i.p.), attenuated the hypothermic effect of morphine (10 mg/kg), a histamine H2 receptor antagonist, ranitidine (100 mg/kg, i.p.), had no effect. These results suggest that the hypothermic effect of morphine in mice is mediated, at least partly, through histamine H1 receptors.

ROSIGLITAZONE, AN AGONIST OF PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR-GAMMA, PREVENTS CONTRALATERAL TESTICULAR ISCHAEMIA–REPERFUSION INJURY IN PREPUBERTAL RATS

1 Rosiglitazone plays a positive role in the reparation of ischaemia–reperfusion (I/R) injury in different tissues. Thus, we examined its biochemical and histological effects on the contralateral testes to determine whether exogenous rosiglitazone affords any protection against testicular damage. 2 Forty‐eight prepubertal male Wistar‐Albino rats were divided into six groups. Testicular torsion was created by rotating the right testis 720° in a clockwise direction for 5 h in all groups except group I, which was the sham‐control group. In group II, bilateral orchiectomy was performed following the torsion period. After detorsion both testes were removed in the fifth hour in group III and on the seventh day in group IV. In group V, one‐shot rosiglitazone (4 mg/kg) was administered 40 min before detorsion and both testes were removed following the torsion period. In group VI, rosiglitazone was administered (4 mg/kg) 40 min before detorsion and for 7 days, and then both testes were harvested. The tissue levels of malondialdehyde (MDA) were measured and mean testicular biopsy score (MTBS) and mean seminiferous tubule diameter (MSTD) were examined. Immunoexpression of endothelial nitric oxide synthase (eNOS) in testes tissues was investigated by immunohistochemical studies. 3 In the contralateral testis, the MTBS and MSTD values of group VI were significantly higher than those in group IV. Immunohistochemically, mild eNOS immunostaining was present in the germ cells of the contralateral testes in group IV after I/R. In group VI, intense eNOS immunoreactivity was seen in the contralateral testes. 4 Rosiglitazone reduces contralateral testicular damage formed after unilateral testicular torsion and alleviates the oxidative events.

The Protective Effect of Moclobemide Against Hypoxia-Induced Lethality in Mice Is Not Due to a Decrease in Body Temperature

The protective effect of moclobemide, a reversible and highly selective inhibitor of monoamine oxidase-A, against hypoxia-induced lethality was investigated in the present experiment. Moclobemide showed an apparent protective potency against hypoxia and significantly prolonged the latencies for convulsions and death in a dose-dependent manner. Hypothermia is known to protect animals from hypoxia. Moclobemide also decreased body temperature in mice; however, the hypothermic effect was unrelated to the antihypoxic effect. These results suggest that the protective effect of moclobemide in hypoxia is not due to a decrease in body temperature.

The Protective Effect of Curcumin on Ionizing Radiation-induced Cataractogenesis in Rats

OBJECTIVE The aim of the study was to determine the protective effect of curcumin against ionizing radiation-induced cataract in the lens of rats. MATERIAL AND METHODS Rats were divided into six groups. Group 1: Control, Group 2: Dimethyl sulfoxide (DMSO), Group 3: DMSO+curcumin, Group 4: Irradiation, Group 5: Irradiation+DMSO, Group 6: Irradiation+DMSO+curcumin. A 15 Gy total dose was given to 4, 5, 6 groups for radiation damage. Curcumin (100 mg/kg) was dissolved in DMSO and given by intragastric intubation for 28 days. At the end of the experiment, lenses were graded and enucleated. The lenticular activity of the antioxidant enzymes, total antioxidant and glutathione peroxidase (GSH-Px), and the malondialdehyde (MDA) were measured. RESULTS 100% Cataract was seen in the irradiation group. Cataract rate fell to 40% and was limited at grade 1 and 2 in the curcumin group. In the irradiation group, antioxidant enzyme levels were decreased, MDA levels were increased. There was an increase in antioxidant enzyme levels and a significant decrease in MDA in the group which was given curcumin. CONCLUSION Curcumin has antioxidant and radioprotective properties and is likely to be a valuable agent for protection against ionizing radiation. Hence, it may be used as an antioxidant and radioprotector against radiation-induced cataractogenesis.

Effect of Curcumin on Ipsilateral and Contralateral Testes after Unilateral Testicular Torsion in a Rat Model

Objective: The aim of the study was to determine the protective effect of curcumin on testicular ischemia-reperfusion (I/R) injury. Materials and Methods: 32 male rats were divided into four groups (n = 8): group 1: control; group 2: ischemia; group 3: I/R, and group 4: I/R+CUR. Curcumin (150 mg/kg, p.o.) was administered before 30 min of reperfusion in group 4. Malondialdehyde (MDA) levels, Johnsen’s testicular biopsy scores, and mean seminiferous tubule diameter measurements were evaluated in testes. In addition, endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) expressions were evaluated immunohistochemically. Results: MDA levels in control groups were significantly lower than other groups in ipsilateral and contralateral testes. Johnsen’s scores in the control group were significantly higher than in other groups. MDA levels and Johnsen’s scores in the I/R+CUR group were similar to the ischemia and I/R groups in ipsilateral and contralateral testes. The immunoreactivity of iNOS and eNOS were increased in I/R ipsilateral testicular groups. After I/R, iNOS and eNOS expression increased slightly in contralateral groups. Additionally, the curcumin treatment decreased iNOS and eNOS immunoreactivity in ipsilateral and contralateral testes. Conclusion: The results suggest that curcumin did not protect the unilateral nor contralateral testes. This observation may depend on inhibition of iNOS and eNOS due to inhibition of the antioxidant, anti-inflammatory effects of nitric oxide.

Compound 48/80, a histamine-depleting agent, blocks the protective effect of morphine against electroconvulsive shock in mice

We have shown that morphine has an anticonvulsive effect against maximal electroconvulsive shock (MES) in mice, and this effect is antagonized by histamine H1-receptor antagonists. Brain histamine is localized both in neurons and in mast cells, and morphine is known to enhance the turnover of neuronal histamine and to release histamine from mast cells. In the present experiments, compound 48/80 was injected chronically (0.5 mg/kg on day 1, 1 mg/kg on day 2, 2 mg/kg on day 3, 3 mg/kg on day 4, and 4 mg/kg on day 5, twice daily, ip) to deplete mast cell contents. Morphine (0.001-10 mg/kg, ip; N = 20) produced a dose-dependent anticonvulsive effect against MES seizure in mice with non-depleted mast cells, whereas it did not exert any anticonvulsive effect in mice with depleted mast cells. These results indicate that morphine produces its anticonvulsive effect against maximal electroconvulsive shock in mice by liberating histamine from mast cells.

METHYLENE BLUE INCREASES CONTRALATERAL TESTICULAR ISCHAEMIA–REPERFUSION INJURY AFTER UNILATERAL TESTICULAR TORSION

1 Testicular ischaemia–reperfusion injury is commonly seen in childhood. Infertility occurs in 25% of patients after unilateral testicular ischaemia. It is has been reported that methylene blue has a positive effect in the reparation of ischaemia–reperfusion injury in different tissues. Therefore, we hypothesized that methylene blue may prevent the hazardous effects of ischaemia–reperfusion injury in testicular tissue after unilateral testicular torsion. 2 Thirty‐two prepubertal Wistar‐albino rats were divided into four groups. Testicular torsion was created by rotating the right testis 720° in a clockwise direction for 5 h in all groups except for Group C, which was the sham control group. In Group T, bilateral orchiectomy was performed following the torsion period. In Group TD, both testes were removed 5 days after the torsion period. In Group MB, methylene blue (1 mg/kg, i.p.) was administered 40 min before detorsion and once daily over 5 days; then, both testes were harvested. Tissue levels of malondialdehyde (MDA), serum levels of creatine kinase (CK), mean testicular biopsy score (MTBS) and mean seminifer tubule diameter (MSTD) were determined. 3 There was a significant difference in MTBS between Groups T and TD (P < 0.05) in both ipsilateral and contralateral testes. In the contralateral testis, treatment with methylene blue decreased MTBS and MSTD (P < 0.05) and increased MDA levels (P < 0.05). In Group T, mean serum CK concentrations were higher than in any of the other groups (P < 0.05). 4 After 5 h of unilateral testicular torsion and a 5 day reperfusion period, serious tissue damage occurred on both the ipsilateral and contralateral sides. Serum CK concentrations may be an indicator for ischaemia, but not for ischaemia–reperfusion injury. Contrary to our hypothesis, methylene blue increased contralateral testicular damage after unilateral testicular torsion and exacerbated oxidative events.

The role of nitric oxide in the protective effect of insulin against pentylenetetrazole-induced seizures in mice

Both insulin, depending on the glycemic state, and nitric oxide (NO), depending on the experimental conditions, have been suggested to have either proconvulsant or anticonvulsant effects. It is also known that NO plays an important role in some of the peripheral effects of insulin. The aim of the present study was to investigate the effects of NO and insulin against convulsions produced by pentylenetetrazole (PTZ, 60 mg/kg, i.p.) in mice and whether NO plays a role in the effect of insulin. Nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine-methyl ester (L-NAME, 1-100 mg/kg, i.p.) shortened the onset of PTZ-induced convulsioins and increased the incidence and mortality rate, at the higher doses. Insulin (1 U/kg, i.p.), when given with dextrose (3 g/kg, i.p.) to counteract the hypoglycemic effect of the hormone, prolonged the onset of convulsions and decreased the incidence and mortality rate. L-NAME pretreatment (3 mg/kg, i.p.), at the dose which it produced no effect on PTZ-induced convulsions, attenuated the protective effect of 1 U/kg insulin + 3 g/kg dextrose combination significantly. Concomitant administration of the NO synthesis precursor, L-arginine (500 mg/kg), completely reversed this facilitatory effect of L-NAME. Our results indicate that NO has a protective effect against PTZ-induced convulsions in mice; insulin has a similar effect when given with dextrose; and, NO production may play an important role in the anticonvulsant effect of insulin.