The Effect of Experimental Diabetes on the Twenty‐Four‐Hour Pattern of the Vasodilator Responses to Acetylcholine and Isoprenaline ın the Rat Aorta

The aim of this study was to investigate whether time‐dependent variations in the relaxant effect of acetylcholine, an endothelium‐dependent vasorelaxant via muscarinic receptors, and isoprenaline, a nonselective β‐adrenoceptor agonist in rat aorta, are influenced by streptozotocin (STZ)‐induced experimental diabetes. Adult male rats were divided randomly into two groups: control and STZ‐induced (STZ, 55 mg/kg, intraperitoneal) diabetes. The animals were synchronized to a 12∶12 h light‐dark cycle (lights on 08∶00 h) and sacrificed at six different times of day (1, 5, 9, 13, 17, and 21 hours after lights on; HALO) eight weeks after STZ injection. The in vitro responsiveness of thoracic aorta rings obtained from control and diabetic rats to acetylcholine (10^?9–10^?5 M) and isoprenaline (10^?10–10^?3 M) was determined in six different times. EC₅₀ (the concentration inducing half of the maximum response) values and maximum responses were calculated from cumulative concentration‐response curves of the agonists and were analyzed with respect to time and STZ treatment. Treatment, time, and interactions between treatment and time were tested by two‐way analysis of variance (ANOVA). To analyze differences due to biological time, one‐way ANOVA was used. STZ treatment did not significantly change EC₅₀ values or maximum responses for both agonists. There were statistically significant time‐dependent variations in the EC₅₀ values for isoprenaline and maximum responses for both acetylcholine and isoprenaline in control groups by one‐way ANOVA, but significant time‐dependent variations disappeared in the aortas isolated from STZ‐induced diabetic rats. The vasodilator responses to acetylcholine and isoprenaline failed to show any significant interaction (treatment×time of study) between STZ treatment and time of sacrifice in both EC₅₀ values and maximum responses by two‐way ANOVA. These results indicate there is a basic temporal pattern in the responses to acetylcholine and isoprenaline in rat aorta which continues in diabetes. It is shown for the first time that experimental diabetes does not change the 24 h pattern of responses to acetylcholine and isoprenaline, and that time‐dependent variations in the responses to these agonists disappear in diabetic animals. Although further studies are required to define the underlying mechanism(s) of these findings, results suggest that experimental diabetes can modify the time‐dependent vasorelaxant responses of rat aorta. This may help to understand the circadian rhythms in cardiovascular physiology and pathology or in drug effects in diabetes.     

The effect of experimental diabetes on the twenty-four-hour pattern of the vasodilator responses to acetylcholine and isoprenaline in the rat aorta

The aim of this study was to investigate whether time-dependent variations in the relaxant effect of acetylcholine, an endothelium-dependent vasorelaxant via muscarinic receptors, and isoprenaline, a nonselective β-adrenoceptor agonist in rat aorta, are influenced by streptozotocin (STZ)-induced experimental diabetes. Adult male rats were divided randomly into two groups: control and STZ-induced (STZ, 55 mg/kg, intraperitoneal) diabetes. The animals were synchronized to a 12:12 h light-dark cycle (lights on 08:00 h) and sacrificed at six different times of day (1, 5, 9, 13, 17, and 21 hours after lights on; HALO) eight weeks after STZ injection. The in vitro responsiveness of thoracic aorta rings obtained from control and diabetic rats to acetylcholine (10^-9-10^-5 M) and isoprenaline (10^-10-10^-3 M) was determined in six different times. EC₅₀ (the concentration inducing half of the maximum response) values and maximum responses were calculated from cumulative concentration-response curves of the agonists and were analyzed with respect to time and STZ treatment. Treatment, time, and interactions between treatment and time were tested by two-way analysis of variance (ANOVA). To analyze differences due to biological time, one-way ANOVA was used. STZ treatment did not significantly change EC₅₀ values or maximum responses for both agonists. There were statistically significant time-dependent variations in the EC₅₀ values for isoprenaline and maximum responses for both acetylcholine and isoprenaline in control groups by one-way ANOVA, but significant time-dependent variations disappeared in the aortas isolated from STZ-induced diabetic rats. The vasodilator responses to acetylcholine and isoprenaline failed to show any significant interaction (treatment×time of study) between STZ treatment and time of sacrifice in both EC₅₀ values and maximum responses by two-way ANOVA. These results indicate there is a basic temporal pattern in the responses to acetylcholine and isoprenaline in rat aorta which continues in diabetes. It is shown for the first time that experimental diabetes does not change the 24 h pattern of responses to acetylcholine and isoprenaline, and that time-dependent variations in the responses to these agonists disappear in diabetic animals. Although further studies are required to define the underlying mechanism(s) of these findings, results suggest that experimental diabetes can modify the time-dependent vasorelaxant responses of rat aorta. This may help to understand the circadian rhythms in cardiovascular physiology and pathology or in drug effects in diabetes.     

An unusual patient with hypercalciuria, recurrent nephrolithiasis, hypomagnesemia and G227R mutation of Paracellin-1. An unusual patient with hypercalciuria and hypomagnesemia unresponsive to thiazide diuretics

A 19-year-old female patient with hypercalciuria and recurrent nephrolithiasis/urinary tract infection unresponsive to thiazide type diuretics is presented. The patient first experienced nephrolithiasis at the age of 4 years. Afterwards, recurrent passages of stones and urinary tract infection occurred. On diagnostic evaluation at the age of 19 years, she also had hypocitraturia and hypomagnesemia. Her serum calcium concentrations were near the lower limit of normal (8.5-8.8 mg/dl; normal range: 8.5-10.5), her serum magnesium concentrations were 1.15-1.24 mg/dl (normal range: 1.4-2.5) and urinary calcium excretion was 900 mg/24 h. PTH concentrations were increased (110-156 pg/ml; normal range: 10-65). We tried to treat the patient with hydrochlorothiazide at a dose of 50 mg/day. During treatment with thiazide diuretics, PTH concentration remained high and the patient had recurrent urinary tract infections and passages of stones. Serum magnesium concentration did not normalize even under the parenteral magnesium infusion. Her mother had a history of nephrolithiasis 20 years ago. Severe hypomagnesemia in association with hypercalciuria/urinary stones is reported as a rare autosomal recessive disorder caused by impaired reabsorption of magnesium and calcium in the thick assending limp of Henle's loop. Recent studies showed that mutations in the CLDN16 gene encoding paracellin-1 cause the disorder. In exon 4, a homozygous nucleotide exchange (G679C) was identified for the patient. This results in a point mutation at position Glycine227, which is replaced by an Arginine residue (G227R). The mother was heterozygous for this mutation. G227 is located in the fourth transmembrane domain and is highly conserved in the claudin gene family. This case indicates the pathogenetic role of paracellin-1 mutation in familial hypomagnesemia with hypercalciuria and nephrocalcinosis and further underlines the risk of stone formation in heterozygous mutation carriers.     

The effect of shock wave lithotripsy on nitric oxide and malondialdehyde levels in plasma and urine samples

Shock wave lithotripsy (SWL) is accepted as the first treatment choice for most urinary stones, but it has adverse effects on the kidneys. The mechanisms underlying shock wave-induced renal injury have been discussed and include shear stress, thermal and cavitation effects and free radical formation. We investigated the effects of SWL on plasma and urinary nitrite, a stable metabolite of nitric oxide (NO), and malondialdehyde (MDA) concentrations. Between February and October 2004, 12 men and 8 women with renal calculi were treated using a Dornier MPL-9000 lithotriptor. The ages ranged from 22 to 45 years (average age: 33.7 years). Plasma and urinary NO and MDA levels were analysed before, immediately after, 30 and 60 min and 24 h after SWL. Plasma NO levels were higher than baseline levels immediately, and at 30, 60 min and 24 h after treatment (p = 0.016, p = 0.031, p = 0.033 and p = 0.045, respectively). Simultaneously, the mean urinary NO levels also showed significant elevation after SWL compared with baseline values, except for 24 h (p = 0.021, p = 0.023 and p = 0.048, respectively). The mean levels of plasma MDA showed statistically significant elevation immediately, and 30 and 60 min after SWL termination compared with pre-SWL values (p = 0.012, p = 0.008 and p = 0.012, respectively). Urinary MDA levels obtained immediately (p = 0.035), and 30 (p = 0.006) and 60 (p = 0.045) min after SWL were increased compared to pre-SWL values. We speculate that SWL treatment causes oxidative stress caused by renal ischemia-reperfusion (I/R) injury. Additionally, the increase of NO production may have prevented renal damage caused by vasoconstriction.     

Synthesis and structure-antituberculosis activity relationship of 1H-indole-2,3-dione derivatives

New series of 5-fluoro-1H-indole-2,3-dione-3-thiosemicarbazones 2a-k and 5-fluoro-1-morpholino/piperidinomethyl-1H-indole-2,3-dione-3-thiosemicarbazones 3a-r were synthesized. The structures of the synthesized compounds were confirmed by spectral data, elemental and single crystal X-ray diffraction analysis. The new 5-fluoro-1H-indole-2,3-dione derivatives, along with previously reported 5-nitro-1H-indole-2,3-dione-3-thiosemicarbazones 2l-v, 1-morpholino/piperidinomethyl-5-nitro-1H-indole-2,3-dione-3-thiosemicarbazones 4a-l, and 5-nitro-1H-indole-2,3-dione-3-[(4-oxo-1,3-thiazolidin-2-ylidene)hydrazones] 5a-s, were evaluated for in vitro antituberculosis activity against Mycobacterium tuberculosis H37Rv. Among the tested compounds, 5-nitro-1H-indole-2,3-dione-3-thiosemicarbazones (2p, 2r, and 2s) and its 1-morpholinomethyl derivatives (4a, 4e, 4g, and 4i) exhibited significant inhibitory activity in the primary screen. The antituberculosis activity of molecules with diverse skeletons was investigated by means of the Electronic-Topological Method (ETM). Ten pharmacophores and ten anti-pharmacophores that have been found by this form the basis of the system capable of predicting the structures of potentially active compounds. The forecasting ability of the system has been tested on structures that differ from those synthesized. The probability of correct identification for active compounds was found as equal to 93% in average. To obtain the algorithmic base for the activity prediction, Artificial Neural Networks were used after the ETM (the so-called combined ETM-ANN method). As the result, only 9 pharmacophores and anti-pharmacophores were chosen as the most important ones for the activity. By this, ANNs classified correctly 94.4%, or 67 compounds from 71.     

Mitral and tricuspid annular velocities determined by Doppler tissue imaging in hypopituitary, growth hormone-deficient patients

BACKGROUND: The aim of this study is to determine systolic and diastolic velocity profiles of the left and right ventricles by tissue Doppler imaging (TDI) and to reveal the associations between TDI parameters and early atherosclerotic changes in adult hypopituitary patients with GH deficiency. PATIENTS AND METHODS: The study group is composed of 16 hypopituitary, GH-deficient patients and 13 healthy controls. All patients had been receiving adequate substitution therapy other than GH at stable doses for at least 6 months. Conventional Doppler echocardiography and TDI of the mitral and tricuspid annulus were performed. Intima-media thickness (IMT) of the common carotid artery was calculated. RESULTS: IMT was significantly higher in the hypopituitary group compared with controls (0.83 +/- 0.25 vs. 0.51 +/- 0.14 mm, p < 0.001). Hypopituitary patients had significantly lower peak early diastolic (Em) mitral annular velocity (11.2 +/- 3.0 vs. 13.9 +/- 2.8 cm/s, p < 0.05). Multiple regression analysis revealed that age was the only independent variable significantly associated with Em and IMT in the patients. CONCLUSION: Diastolic abnormalities on TDI of the mitral annulus and early atherosclerotic changes occur concurrently in asymptomatic hypopituitary patients with GH deficiency. Aging may have a more deleterious effect on ventricular function and atherogenesis in this group of patients.     

Synthesis, antioxidant and radical scavenging activities of novel benzimidazoles

The synthesis and antioxidant evaluation of some novel benzimidazole derivatives (10-24) are described. Antioxidant properties of the compounds were investigated employing various in vitro systems viz., microsomal NADPH-dependent inhibition of lipid peroxidation (LP), interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and scavenging of superoxide anion radical. Compounds 12 and 13 showed very good antioxidant capacity and were 17-18-fold more potent than BHT (IC50 2.3 x 10(-4) M) with 1.3 x 10(-5) M and 1.2 x 10(-5) M IC50 values, respectively, by interaction of the stable DPPH free radical.     

Lack of a time-dependent effect of melatonin on radiation-induced apoptosis in cultured rat lymphocytes

Ionizing radiation is widely used for the treatment of solid tumors and it is thought to act by directly targeting tumor clonogens, also known as stem cells. Apoptosis is a genetically programmed mechanism of cell death often characterized by internucleosomal DNA cleavage. Although it has been previously shown that lymphocytes readily undergo apoptosis in patients receiving anticancer drugs or treatment with ionizing radiation, this is the first study to investigate the influence of radiotherapy and melatonin on apoptosis in rat lymphocytes at two different times of the day. Melatonin, a free radical scavenger, is an endogenous neurohormone predominantly synthesized in and secreted by the pineal gland. It has been shown that melatonin inhibits apoptosis in normal cells but it increases the rate of apoptosis in various cancer cells. Therefore, in the present study, the effect of melatonin on apoptosis in cultured lymphocytes was studied after total body irradiation (TBI) was given to rats in the morning (1 HALO) or evening (13 HALO) with morphological and DNA fragmentation analysis. Two-way analysis of variance (ANOVA) revealed that radiation increased the rate of apoptosis in rat lymphocytes after TBI, and melatonin treatment did not reduce the rate of apoptosis after TBI at either time point. We conclude that the lack of an effect of melatonin on the apoptosis rate in rat lymphocytes might be due to the dose-dependent effect of melatonin, the time course of apoptosis investigated, or the cell type in which apoptosis was examined.