Involvement of oxidative stress in ascorbate-induced proapoptotic death of PC12 cells

Ascorbate is a reducing agent, but it is also known to oxidize cellular components under specific conditions. The mechanism of this oxidative action, however, is not well established. Ascorbate treatment increased lipid peroxide content in PC12 cells, but did not increase quantities of lipid peroxide when homogenates of PC12 cells were treated with ascorbate, suggesting that cellular integrity is required for ascorbate to generate lipid peroxidation. However, dehydroascorbate increased lipid peroxide production in both intact PC12 cells and the cell homogenates. These differential effects of ascorbate and dehydroascorbate on intact cells versus homogenates suggest that the dehydroascorbate in cytosol induces an oxidative stress. Ascorbate in culture medium is rapidly oxidized to dehydroascorbate, which is transported into cells by a glucose transporter (GLUT). The GLUT antagonists wortmannin and cytochalasin B, or a high concentration of glucose, blocked (14)C uptake (from ascorbate) in a time-dependent manner and suppressed lipid peroxide production in PC12 cells. These observations support the concept that ascorbate is oxidized to dehydroascorbate, which is transported into cells via GLUT. The dehydroascorbate induces oxidative stress. The oxidative stress triggered apoptosis according to ceramide production, caspase-3 activation, and TUNEL. We have concluded that ascorbate is taken up after oxidation to dehydroascorbate via a "dehydroascorbate transporter" (GLUT), and the dehydroascorbate generates an oxidative stress which triggers apoptosis. These studies have significant implications for conditions under which a high concentration of ascorbate in a tissue is released during a period of hypoxia (e.g., stroke) and taken up during a reperfusion period as dehydroascorbate. Inhibiting uptake of dehydroascorbate may offer novel therapeutic strategies to alleviate brain damage during a reperfusion period.

Carriage of antibiotic-resistant pneumococci among Asian children: a multinational surveillance by the Asian Network for Surveillance of Resistant Pathogens (ANSORP)

To investigate the nasal carriage of antibiotic-resistant pneumococci by children, anterior nasal swabs were done for 4963 children <5 years old in 11 countries in Asia and the Middle East. In total, 1105 pneumococci isolates (carriage rate, 22.3%) were collected, 35.8% of which were found to be nonsusceptible to penicillin. Prevalence of penicillin nonsusceptibility was highest in Taiwan (91.3%), followed by Korea (85.8%), Sri Lanka (76.5%), and Vietnam (70.4%). Penicillin resistance was related to residence in urban areas, enrollment in day care, and a history of otitis media. The most common serogroups were 6 (21.5%), 23 (16.5%), and 19 (15.7%). The most common clone, as assessed by pulsed-field gel electrophoresis, was identical to the Spanish 23F clone and to strains of invasive isolates from adult patients. Data in this study documented the high rate of penicillin or multidrug resistance among isolates of pneumococci carried nasally in children in Asia and the Middle East and showed that this is due to the spread of a few predominant clones in the region.

Peripheral blood mitochondrial DNA content is inversely correlated with insulin secretion during hyperglycemic clamp studies in healthy young men

Abnormalities in mitochondrial DNA(mtDNA) have been implicated in the pathogenesis of diabetes mellitus. We recently reported that decreased mtDNA content precedes the development of diabetes mellitus and is associated with parameters of insulin resistance. In this study, we examined whether there is any relation between mtDNA content and insulin secretion. We compared the mtDNA content of peripheral blood leukocytes with the parameters of insulin secretion measured by hyperglycemic clamp in a group of healthy young men. There were statistically significant correlations between mtDNA content in peripheral blood and fasting plasma insulin (r=-0.43, P<0.05) and C-peptide levels (r=-0.44, P<0.05). MtDNA content also correlated negatively with acute insulin response(r=-0.48, P<0.05), late insulin response (r=-0.50, P<0.05) during hyperglycemic clamp and insulin secretion after glucagon stimulation (r=-0.60, P<0.01). mtDNA content in peripheral blood correlated negatively with homeostasis model (HOMA) insulin resistance (r=-0.45, P<0.05) although it did not correlate with the insulin insensitivity index (M/I) during hyperglycemic clamp. In summary, the mtDNA content of peripheral blood correlated negatively with indices of insulin resistance and insulin secretion in healthy young men. The compensatory response of pancreas beta cells to insulin resistance might contribute in part to increased insulin secretion in these subjects.

Molecular typing of methicillin-resistant Staphylococcus aureus by pulsed-field gel electrophoresis: comparison of results obtained in a multilaboratory effort using identical protocols and MRSA strains

Pulsed-field gel electrophoresis (PFGE) has become the gold standard of molecular methods in epidemiological investigations. In spite of its high resolving power, use of the method has been hampered by inadequate laboratory-to-laboratory reproducibility. In the project described here we have addressed this problem by organizing a multilaboratory effort in which the same bacterial strains (subtype variants of the Iberian and Brazilian methicillin-resistant Staphylococcus aureus--MRSA--clones) were analyzed by twenty investigators in thirteen different laboratories according to an indentical protocol, which is reproduced here in detail. PFGE patterns obtained were analyzed at a central laboratory in order to identify specific technical problems that produced substandard macrorestriction patterns. The results including the specific technical problems and their most likely causes are described in this communication. Also listed are seven major epidemic clones of MRSA which have been characterized by molecular fingerprinting techniques and the prototypes of which have been deposited at the American Type Culture Collection, from where they will be available for interested investigators for the purpose of typing MRSA isolates. It is hoped that this communication will contribute to the improvement of the reproducibility and technical/aesthetic quality of PFGE analysis.

A co-operative study: clinical characteristics of 334 Korean patients with moyamoya disease treated at neurosurgical institutes (1976-1994). The Korean Society for Cerebrovascular Disease

A co-operative study was conducted to determine the clinical characteristics of patients with moyamoya disease who were diagnosed and treated at neurosurgical institutes in Korea before 1995. Twenty-six hospitals contributed 505 cases and among them, the clinical characteristics of 334 patients with definite moyamoya disease were evaluated. The number of patients began to increase from the late 1980s, and after that approximately 20 patients were treated each year. There were two age peaks: from six to 15 and from 31 to 40 years of age. Haemorrhagic manifestations occurred in approximately 43% of the patients. The major clinical manifestations were haemorrhage in adults (62.4%) and ischaemia in children (61.2%). Overall 54.5% of the patients experienced decreased consciousness levels, mainly due to intracranial haemorrhage or cerebral infarction. In the patients with ischemic manifestations, the adult patients were more likely to have cerebral infarction than the pediatric patients (80% vs. 39%) and the pediatric patients were more likely to have TIA (61% vs. 25%). Thirty eight percent of the patients underwent bypass surgery and 53% of these procedures were performed bilaterally. Treatment policies, including indications for bypass surgery and commonly used drugs, were somewhat different according to the institution. Overall favorable outcome was 73%, and the most significant factor affecting poor outcome was haemorrhagic manifestation. This article describes the characteristics of 334 patients with moyamoya disease, who were diagnosed and treated at neurosurgical institutes in Korea before 1995.

Effects of fetal bovine serum on ferrous ion-induced oxidative stress in pheochromocytoma (PC12) cells

Ferrous ion (Fe2+) has been considered to be a cause of neuronal oxidative injury. Since body fluids contain protein and serum is an essential component of tissue culture medium, we have examined the role of serum protein on Fe2+-mediated oxidative stress using PC12 cells and rat cerebral cortices. Fe2+ or the combination of ascorbate and Fe2+ increased concentrations of thiobarbituric acid reactive substances (TBARS) in PC12 cells and cerebrocortical homogenates in medium (RPMI 1640), but did not increase TBARS when the medium was supplemented with 10% fetal bovine serum. Treatment with ascorbate/Fe2+ in serum-free medium reduced endogenous glutathione (GSH) concentration in PC12 cells. However, the medium supplemented with serum did not reduce GSH concentrations. PC12 cell death induced by ascorbate/Fe2+ was alleviated by increasing serum or bovine albumin concentrations in the medium. These observations indicated that oxidative injury caused by the transition metal ion could be lessened by adding fetal bovine serum to culture medium.

Oxidative stress induced by ascorbate causes neuronal damage in an in vitro system

Of particular physiological interest, ascorbate, the ionized form of ascorbic acid, possesses strong reducing properties. However, it has been shown to induce oxidative stress and lead to apoptosis under certain experimental conditions. Ascorbate in the brain is released during hypoxia, including stroke, and is subsequently oxidized in plasma. The oxidized product (dehydroascorbate) is transported into neurons via a glucose transporter (GLUT) during a reperfusion period. The dehydroascorbate taken up by cells is reduced to ascorbate by both enzymatic and non-enzymatic processes, and the ascorbate is stored in cells. This reduction process causes an oxidative stress, due to coupling of redox reactions, which can induce cellular damage and trigger apoptosis. Ascorbate treatment decreased cellular glutathione (GSH) content, and increased the rates of lipid peroxide production in rat cortical slices. Wortmannin, a specific inhibitor of phosphatidylinositol (PI)-3-kinase (a key enzyme in GLUT translocation), prevented the ascorbate induced-decrease of GSH content, and suppressed ascorbate-induced lipid peroxide production. However, wortmannin was ineffective in reducing hydrogen peroxide (H(2)O(2))-induced oxidative stress. The oxidative stress caused ceramide accumulation, which was proportionally changed with lipid peroxides when the cortical slices were treated with ascorbate. These differential effects support the hypothesis that GLUT efficiently transports the dehydroascorbate into neurons, causing oxidative stress.

Enhanced level of n-3 fatty acid in membrane phospholipids induces lipid peroxidation in rats fed dietary docosahexaenoic acid oil

The effect of dietary docosahexaenoic acid (DHA, 22:6n-3) oil with different lipid types on lipid peroxidation was studied in rats. Each group of male Sprague-Dawley rats was pair fed 15% (w/w) of either DHA-triglycerides (DHA-TG), DHA-ethyl esters (DHA-EE) or DHA-phospholipids (DHA-PL) for up to 3 weeks. The palm oil (supplemented with 20% soybean oil) diet without DHA was fed as the control. Dietary DHA oils lowered plasma triglyceride concentrations in rats fed DHA-TG (by 30%), DHA-EE (by 45%) and DHA-PL (by 27%), compared to control. The incorporation of dietary DHA into plasma and liver phospholipids was more pronounced in the DHA-TG and DHA-EE group than in the DHA-PL group. However, DHA oil intake negatively influenced lipid peroxidation in both plasma and liver. Phospholipid peroxidation in plasma and liver was significantly higher than control in rats fed DHA-TG or DHA-EE, but not DHA-PL. These results are consistent with increased thiobarbituric acid reactive substances (TBARS) and decreased alpha-tocopherol levels in plasma and liver. In addition, liver microsomes from rats of each group were exposed to a mixture of chelated iron (Fe(3+)/ADP) and NADPH to determine the rate of peroxidative damage. During NADPH-dependent peroxidation of microsomes, the accumulation of phospholipid hydroperoxides, as well as TBARS, were elevated and alpha-tocopherol levels were significantly exhausted in DHA-TG and DHA-EE groups. During microsomal lipid peroxidation, there was a greater loss of n-3 fatty acids (mainly DHA) than of n-6 fatty acids, including arachidonic acid (20:4n-6). These results indicate that polyunsaturation of n-3 fatty acids is the most important target for lipid peroxidation. This suggests that the ingestion of large amounts of DHA oil enhances lipid peroxidation in the target membranes where greater amounts of n-3 fatty acids are incorporated, thereby increasing the peroxidizability and possibly accelerating the atherosclerotic process.

The influence of seasonal factors on the incidence of peritonitis in continuous ambulatory peritoneal dialysis in the temperate zone

Many factors contribute to the development of continuous ambulatory peritoneal dialysis (CAPD) peritonitis. The role of climate in CAPD peritonitis has received relatively little attention. We retrospectively analyzed the incidence of CAPD peritonitis according to temperature and relative humidity. Data from 80 patients were examined. The monthly mean temperature and relative humidity during study period varied between -3.4 degrees C and 25.4 degrees C and between 61% and 81%, respectively. In 1123 patient-months, 53 cases of peritonitis occurred. The occurrence of peritonitis paralleled temperature and relative humidity, being the highest (0.180 episodes/patient-month) in July (mean temperature, 24.6 degrees C; relative humidity, 81%) and lowest (0.013 episodes/patient-month) in November (mean temperature, 6.6 degrees C; relative humidity, 66%). Significant correlations were seen between the monthly frequency of CAPD peritonitis and temperature (r = 0.53, p < 0.05) and relative humidity (r = 0.59, p < 0.05). The incidence was higher in the warm season (months with a mean temperature > or = 15 degrees C, that is, May-September) than in the cold season (months with a mean temperature < 15 degrees C, that is, October-April), at 0.074 episodes/patient-month versus 0.024 episodes/patient-month, p < 0.05. We also found a tendency for gram-negative peritonitis to occur uniformly throughout the year, but for gram-positive peritonitis to increase during hot and humid months, especially the rainy month of July. Gram-positive organisms caused 50% of peritonitis from March to August, but just 17.7% from September to February. Gram-negative organisms caused 7.3% and 29.4% of peritonitis during the same periods (p < 0.05). The results indicate a clear seasonal change in the rate of CAPD peritonitis and in the causative micro-organisms. The observation that CAPD peritonitis increases in the season of high temperature and high humidity suggests the influence of climate on CAPD peritonitis in the temperate zone.

Graded unilateral cervical spinal cord injury in the rat: evaluation of forelimb recovery and histological effects

The purpose of this study was to develop a model of unilateral cervical (C4-C5) spinal cord contusion injury in the rat and to characterize the functional and histological consequences following three injury levels using a new weight-drop spinal cord injury device. We evaluated forepaw/forelimb and hindlimb functions by: (1) a horizontal ladder beam measuring paw misplacements and slips; and (2) the forelimb preference test which measures the forelimb used for pushing off to rear, for support, and to land on after rearing. Rats with a mild spinal cord injury displayed primarily a forepaw deficit (forepaw misplacements) for 8 weeks after injury. Paw preference also improved after injury, but failed to reach control levels even after 12 weeks. These rats had damage primarily to the rubrospinal, spinocervicothalamic, and the uncrossed lateral corticospinal tracts in the dorsolateral funiculus a well as some loss of the lateral spinothalamic tracts in the lateral funiculus. Rats with a moderate injury had a prominent forepaw deficit still evident at 12 weeks after injury as well as a mild but not significant hindlimb deficit. Paw preference improved slightly 12 weeks. There was a larger lesion in the dorsolateral and lateral funiculi than in mildly injured rats which extended into the ventrolateral funiculi. There was a significant loss of gray matter compared to rats with a mild injury. Rats with a severe injury displayed significant forelimb and hindlimb deficits throughout the 12 week testing period compared to rats with a mild or moderate injury, and also had a more severe paw preference bias (90%). The lesion encompassed the entire dorsolateral, lateral and ventrolateral funiculi with some disruption of the ventral funiculus. There was more significant gray matter necrosis compared to rats with either a mild or moderate injury. Thus, the spinal cord injury device we used may be useful for studying graded cervical spinal cord injury in rats and potential treatments or interventions, because both the behavioral and histological effects are reproducible and consistent.

Enhanced neutrophil functions by recombinant human granulocyte colony-stimulating factor in diabetic patients with foot infections in vitro

This study was performed to evaluate the effect of granulocyte-colony stimulating factor on neutrophil functions in diabetic patients with active foot infections in vitro. Twelve diabetic patients with foot infections and 12 normal volunteers were enrolled. Neutrophils from peripheral blood were incubated with granulocyte colony-stimulating factor (G-CSF, 50 ng/mL) for 20 min. Superoxide production of neutrophils was measured by the reduction of ferricytochrome C. Neutrophil phagocytosis was assayed using Staphylococcus aureus and the weighted phagocytic index was calculated. Superoxide production of neutrophils in diabetic patients with foot infections was 7.7 (unit: nmol/2 x 10(5) cells/60 min), which was significantly lower than that in controls (12.0) (p<0.05). G-CSF increased neutrophil superoxide production to 12.1 in diabetic patients with foot infections and to 19.8 in controls (p<0.05 for each). Weighted phagocytic index in diabetic patients with foot infections was 0.77, which was not significantly different from that of the controls (0.69). Weighted phagocytic index was increased significantly by G-CSF to 0.88 in diabetic patients with foot infections and to 0.79 in controls (p<0.05 for each). In conclusion, G-CSF significantly enhanced neutrophil functions in diabetic patients with foot infections in vitro.

Effect of iron and ascorbate on cyclosporine-induced oxidative damage of kidney mitochondria and microsomes

The stimulatory effect of iron and ascorbate on the damaging action of cyclosporine in kidney mitochondria, microsomes and epithelial cells was examined. Cyclosporine induced malondialdehyde formation and hydrogen peroxide production in mitochondria and attenuated the activity of MnSOD and glutathione peroxidase. The damaging effect of cyclosporine (50 microM) plus Fe2+(20 microM) on mitochondrial and microsomal lipids and proteins as well as mitochondrial thiols was greater than the summation of the oxidizing action of cyclosporine alone and Fe2+ alone. As for tissue components, iron enhanced cyclosporine-induced viability loss in kidney epithelial cells. Fe2+, EDTA and H2O2- induced 2-alpha deoxyribose degradation was attenuated by 10 mM DMSO and 200 microM DTPA but not affected by 200 microM cyclosporine. The addition of Fe2+ caused a change in the absorbance spectrum of cyclosporine in the wavelength range 230-350 nm. The simultaneous addition of cyclosporine (50 microM) and ascorbate (100 microM) showed the enhanced peroxidative effect on mitochondrial and microsomal lipids, which was inhibited by DTPA and EDTA (1 mM). Similar to iron, ascorbate enhanced cyclosporine-induced cell viability loss. The results show that iron and ascorbate promote the damaging action of cyclosporine in kidney cortex mitochondria and microsomes and in kidney epithelial cells, which may contribute to the enhancement of cyclosporine-induced nephrotoxicity.

Assessment of total body water from anthropometry-based equations using bioelectrical impedance as reference in Korean adult control and haemodialysis subjects

BACKGROUND

Several indirect prediction equations to estimate total body water (TBW) with simple demographic and anthropometric data are commonly used by researchers and dialysis units. These equations are largely based on observations in subjects of the Western hemisphere. The purpose of this study was to investigate the possible application of anthropometry-based TBW equations to a Korean adult control population and maintenance haemodialysis (HD) patients using multifrequency bioelectrical impedance analysis (BIA) as reference.

METHODS

We performed BIA and anthropometric measurements in 67 healthy adults and 101 HD patients. Four anthropometry-based equations were used: 58% of actual body weight (TBW-58), the Watson formula (TBW-W), the Hume formula (TBW-H), and the Chertow formula (TBW-C). Multifrequency BIA was performed at fasting state in controls and after HD.

RESULTS

TBW-BIA was 34.6+/-6.9 l in control and 29.9+/-5.1 l in HD patients. TBW-58 and TBW-C gave significantly greater TBWs than TBW-BIA in both control and HD subjects. The correlation coefficients of TBW-BIA with calculated TBWs were lowest in TBW-58 (0.754 in control and 0.856 in HD subjects), and highest in TBW-C (0.944 in control and 0.916 in HD subjects). Mean prediction error was greatest in the Chertow formula for control and HD patients. Mean prediction error, limits of agreement, and root mean square error were lowest between TBW-BIA and TBW-H in control and between TBW-BIA and TBW-W in HD subjects. The correlation coefficient in the Bland-Altman plot was closer to zero and parallel with TBW-W than TBW-H in control and HD subjects.

CONCLUSION

Currently available TBW equations overestimate TBW in both Korean normal control subjects and HD patients. Among them, the Watson formula appears to be the closest to TBW and to have the least bias. Based on this analysis, it is reasonable to use the Watson formula for the calculation of TBW in Korean adult control and HD subjects until an Asian-based TBW equation is available.

Bladder tumor detection at virtual cystoscopy

PURPOSE

To investigate the utility of computed tomographic (CT) virtual cystoscopy in the detection of bladder tumors.

MATERIALS AND METHODS

Twenty-six patients suspected or known to have bladder neoplasms underwent CT virtual and conventional cystoscopy. The bladder was insufflated with carbon dioxide through a Foley catheter. Helical CT of the bladder was then performed. The data were downloaded to a workstation for interactive intraluminal navigation. Two radiologists blinded to the results of conventional cystoscopy independently reviewed the transverse and virtual images, with consensus readings for cases with discrepant results.

RESULTS

Thirty-six (90%) of 40 bladder lesions proved at conventional cystoscopy were detected with a combination of transverse and virtual images. Four (10%) of 40 bladder lesions, all smaller than 5 mm, were undetected. Transverse and virtual images were complementary, since six polypoid lesions smaller than 5 mm depicted on the virtual images were not seen on the transverse images. In contrast, areas of wall thickening were more readily appreciated on transverse images. CT with patients in both supine and prone positions was necessary, since seven (19%) and five (14%) of 36 lesions were seen only on supine and prone images, respectively.

CONCLUSION

CT virtual cystoscopy is a promising technique for use in bladder tumor detection of lesions larger than 5 mm. Optimal evaluation requires adequate bladder distention with the patient in both supine and prone positions and interpretation of both transverse and virtual images.

The effects of ascorbic acid on dopamine-induced death of PC12 cells are dependent on exposure kinetics

The role of ascorbic acid on dopamine (DA) oxidation-mediated cytotoxicity was studied using the PC12 cell line. DA cytotoxicity was slightly attenuated by ascorbic acid, whereas the cytotoxicity of 6-hydroxydopamine (6-OHDA), a DA oxidation product, was markedly potentiated. To elucidate the relationship between the ascorbic acid effect and the degree of DA oxidation, ascorbic acid was added in a time-dependent fashion after DA treatment. We found greater cell death the later ascorbic acid was applied. Treatment of cells with glutathione alleviated DA- and 6-OHDA-induced cell death, while L-buthionine sulfoximine potentiated DA and 6-OHDA cytotoxicity. Ascorbic acid combined with glutathione eliminated the toxicity of DA and 6-OHDA. These results suggest that the interaction between DA and ascorbic acid is dependent upon the degree of DA oxidation and glutathione availability.

Multicenter surveillance study for nosocomial infections in major hospitals in Korea. Nosocomial Infection Surveillance Committee of the Korean Society for Nosocomial Infection Control

BACKGROUND

The goals of a surveillance for nosocomial infections (NIs) are to observe the magnitude and characteristics of NIs and to plan and evaluate policies and guidelines of infection control. This study was designed to determine the rate and distribution of NIs and their causative pathogens in Korean hospitals.

METHODS

Prospective surveillance was performed at 15 acute care hospitals with more than 500 beds during a 3-month period from June to August 1996. The case-finding methods were laboratory-based surveillance for patients in the general wards and a direct review of medical charts done regularly for all the patients in the intensive care units.

RESULTS

A total of 3162 NIs were found among 85,547 discharged patients, with an overall nosocomial infection rate of 3.70 per 100 patients discharged. Urinary tract infections constituted 30.3% of all NIs. Other infections were pneumonias, 17.2%, surgical site infections, 15.5%, and primary bloodstream infections, 14.5%. The infection rate was the highest in neurosurgery (14.21), followed by neurology (8. 62) and ontology services (6.70). The infection rate in intensive care units was higher than it was in the general wards (10.74 vs 2. 57, P =.001). The commonly isolated organisms were Staphylococcus aureus (17.2%), Pseudomonas aeruginosa (13.8%), and Escherichia coli (12.3%).

CONCLUSIONS

This first multicenter surveillance study provided extensive information on the current status and trends of NIs in major hospitals in Korea. The results may contribute to the evaluation of infection control programs and the development of effective strategies in these hospitals.

Polyunsaturated (n-3) fatty acids susceptible to peroxidation are increased in plasma and tissue lipids of rats fed docosahexaenoic acid-containing oils

Docosahexaenoic acid [DHA, 22:6(n-3)], a major component of membrane phospholipids in brain and retina, is profoundly susceptible to oxidative stress in vitro. The extent of this peroxidation in organs when DHA is ingested in mammals, however, is not well elucidated. We investigated the effect of dietary DHA-containing oils (DHA 7.0-7.1 mol/100 mol total fatty acids), in the form of triacylglycerols (TG), ethyl esters (EE) and phospholipids (PL), on tissue lipid metabolism and lipid peroxidation in rats. Groups of Sprague-Dawley rats were fed semipurified diets containing 15 g/100 g test oils and were compared with those fed 80% palm oil and 20% soybean oil as the control (unsupplemented group) for 3 wk. The DHA oil diets markedly increased (P: < 0.05) the levels of DHA in the plasma, liver and kidney, 1.5-1.9, 2.5-3.8 and 2.2-2.5 times the control values, respectively, whereas there was a concomitant reduction (P: < 0.05) in arachidonic acid. All forms of DHA oil caused lower TG concentrations in plasma (P: < 0.05) and liver (P: < 0.05), but had no effect in kidney. The DHA oil-fed rats had greater phospholipid hydroperoxide accumulations in plasma (191-192% of control rats), liver (170-230%) and kidney (250-340%), whereas the alpha-tocopherol level was reduced concomitantly (21-73% of control rats). Consistent with these results, rats fed DHA-containing oils had more thiobarbituric reactive substances in these organs than the controls. Thus, high incorporation of (n-3) fatty acids (mainly DHA) into plasma and tissue lipids due to DHA-containing oil ingestion may undesirably affect tissues by enhancing susceptibility of membranes to lipid peroxidation and by disrupting the antioxidant system.

Dynamic readjustment of parental methylation patterns of the 5'-flank of the mouse H19 gene during in vitro organogenesis

Gametic marks are stably propagated in order to manifest parent of origin-specific expression patterns of imprinted genes in the developing conceptus. Although the character of the imprint has not yet been fully elucidated, there is compelling evidence that it involves a methylation mark. This is exemplified by a region upstream of the H19 gene, which is not only methylated in a parent of origin-specific manner, but also regulates the silencing of the maternal Igf2 and paternal H19 alleles, respectively. We show here that the parental-specific methylation patterns within the differentially methylated domain (DMD) are perturbed in the soma during in vitro organogenesis. Under these conditions, the paternal DMD allele becomes partially demethylated, whereas the maternal DMD allele gains methylation. Despite these effects, there were no changes in allelic Igf2 or H19 expression patterns in the embryo. Finally, we show that although TSA derepresses the paternal H19 allele in ectoplacental cone when in vitro developed, there is no discernible effect on the methylation status of the paternally inherited 5'-flank in comparison to control samples. Collectively, this data demonstrates that the parental mark is sensitive to a subset of environmental cues and that a certain degree of plasticity of the gametic mark is tolerated without affecting the manifestation of the imprinted state.

A case of living-related kidney transplantation in Bartter's syndrome

Bartter's syndrome is a renal tubular disorder characterized by hypokalemia, metabolic alkalosis, increased urinary excretion of potassium and prostaglandins, a relative vascular resistance to the pressor effects of exogenous angiotensin II, and hyperplasia of the juxtaglomerular apparatus. In most patients, the glomerular filtration rate is normal and chronic renal failure does not develop. We report here on a case of living-related kidney transplantation in Bartter's syndrome, in which a non-steroidal anti-inflammatory drug is suspected to be the cause of the end-stage renal disease.

Protective effect of boldine on oxidative mitochondrial damage in streptozotocin-induced diabetic rats

Increased oxidative stress has been suggested to be involved in the pathogenesis and progression of diabetic tissue damage. Several antioxidants have been described as beneficial for oxidative stress-associated diseases. Boldine ([s]-2,9-dihydroxy-1, 10-dimethoxyaporphine) is a major alkaloid found in the leaves and bark of boldo (Peumus boldus Molina), and has been shown to possess antioxidant activity and anti-inflammatory effects. From this point of view, the possible anti-diabetic effect of boldine and its mechanism were evaluated. The experiments were performed on male rats divided into four groups: control, boldine (100 mg kg(-1), daily in drinking water), diabetic [single dose of 80 mg kg(-1)of streptozotocin (STZ), i.p.] and diabetic simultaneously fed with boldine for 8 weeks. Diabetic status was evaluated periodically with changes of plasma glucose levels and body weight in rats. The effect of boldine on the STZ-induced diabetic rats was examined with the formation of malondialdehydes and carbonyls and the activities of endogenous antioxidant enzymes (superoxide dismutase and glutathione peroxidase) in mitochondria of the pancreas, kidney and liver. The scavenging action of boldine on oxygen free radicals and the effect on mitochondrial free-radical production were also investigated. The treatment of boldine attenuated the development of hyperglycemia and weight loss induced by STZ injection in rats. The levels of malondialdehyde (MDA) and carbonyls in liver, kidney and pancreas mitochondria were significantly increased in STZ-treated rats and decreased after boldine administration. The activities of mitochondrial manganese superoxide dismutase (MnSOD) in the liver, pancreas and kidney were significantly elevated in STZ-treated rats. Boldine administration decreased STZ-induced elevation of MnSOD activity in kidney and pancreas mitochondria, but not in liver mitochondria. In the STZ-treated group, glutathione peroxidase activities decreased in liver mitochondria, and were elevated in pancreas and kidney mitochondria. The boldine treatment restored the altered enzyme activities in the liver and pancreas, but not the kidney. Boldine attenuated both STZ- and iron plus ascorbate-induced MDA and carbonyl formation and thiol oxidation in the pancreas homogenates. Boldine decomposed superoxide anions, hydrogen peroxides and hydroxyl radicals in a dose-dependent manner. The alkaloid significantly attenuated the production of superoxide anions, hydrogen peroxide and nitric oxide caused by liver mitochondria. The results indicate that boldine may exert an inhibitory effect on STZ-induced oxidative tissue damage and altered antioxidant enzyme activity by the decomposition of reactive oxygen species and inhibition of nitric oxide production and by the reduction of the peroxidation-induced product formation. Boldine may attenuate the development of STZ-induced diabetes in rats and interfere with the role of oxidative stress, one of the pathogeneses of diabetes mellitus.

Effect of dialysis modalities on gastric myoelectrical activity in end-stage renal disease patients

Gastric motility is controlled by gastric myoelectrical activity, which propagates from the proximal body to the distal antrum at a frequency of 3 cycles/min. In uremic patients, dyspeptic symptoms are common. To investigate whether dialysis modality affects gastric myoelectrical activity in uremic patients, we performed electrogastrography (EGG) in 41 patients without diabetes with end-stage renal disease (ESRD) undergoing hemodialysis (HD; n = 22) and continuous ambulatory peritoneal dialysis (CAPD; n = 19). EGG was performed noninvasively using abdominal surface electrodes in the fasting state before and 4 hours after HD and at empty and 2 hours after CAPD with 2,000 mL of dialysate. There were no significant differences in age, sex, body weight, duration of dialysis, and percentage of patients with upper gastrointestinal (UGI) symptoms (63.6% versus 42.1%). CAPD patients had significantly lower serum albumin levels (3.4 +/- 0.4 versus 3.9 +/- 0.4 g/dL; P < 0.05), greater serum total-cholesterol levels (189 +/- 33 versus 157 +/- 36 mg/dL; P: < 0.05), and greater percentages of patient with early satiety (42.1% versus 13.6%; P < 0.05) than HD patients. Dominant power significantly increased after HD (251.3 +/- 157.5 versus 512.9 +/- 390.0 dB; P < 0.05) but seemed to decrease after CAPD without statistical significance (416.2 +/- 323.6 versus 283.8 +/- 280.7 dB). There was no difference in the normal slow-wave frequency (NSWF) between HD and CAPD patients (predialysis, 60.7% +/- 29.3% versus 52.2% +/- 36.7%; postdialysis, 56.3% +/- 32.0% versus 50.9% +/- 34.2%). Tachygastria significantly increased after CAPD (pre-CAPD, 2.35% +/- 4.3% versus post-CAPD, 10.0% +/- 14.8%; P < 0.05). There was a significant correlation between changes in tachygastria after CAPD and grade of early satiety in CAPD patients with UGI symptoms (r = 0.74; P: < 0.05). Changes in NSWF after CAPD significantly correlated with age (r = -0.51; P: < 0.05). In conclusion, dialysis modalities seem to have different effects on gastric myoelectrical activity in patients with ESRD.

Amitriptyline modulation of Na(+) channels in rat dorsal root ganglion neurons

The effects of amitriptyline, a tricyclic antidepressant, on tetrodotoxin-sensitive and tetrodotoxin-resistant Na(+) currents in rat dorsal root ganglion neurons were studied using the whole-cell patch clamp method. Amitriptyline blocked both types of Na(+)currents in a dose-and holding potential-dependent manner. At the holding potential of -80 mV, the apparent dissociation constants (K(d)) for amitriptyline to block tetrodotoxin-sensitive and tetrodotoxin-resistant Na(+) channels were 4.7 and 105 microM, respectively. These values increased to 181 and 193 microM, respectively, when the membrane was held at a potential negative enough to remove the steady-state inactivation. Amitriptyline dose-dependently shifted the steady-state inactivation curves in the hyperpolarizing direction and increased the values of the slope factors for both types of Na(+) channels. The voltage dependence of the activation of both types of Na(+) channels was shifted in the depolarizing direction. It was concluded that amitriptyline blocked the two types of Na(+) channels in rat sensory neurons by modulating the activation and the inactivation kinetics.

Effect of peritoneal glucose load on plasma leptin concentration in continuous ambulatory peritoneal dialysis patients

This study was performed to investigate the effect of peritoneal glucose load on plasma leptin concentrations in the continuous ambulatory peritoneal dialysis (CAPD) performed on 13 non-diabetic ESRD patients. Plasma leptin and insulin concentrations were measured for 2 hours during a single 2 liter exchange of 1.5% glucose-based dialysate (SPD, n = 6), for 7 days of daily peritoneal dialysis (DPD, n = 7). In DPD, standard full volume (2,000 ml x 4 times/day) exchange was performed immediately after operation. In SPD, plasma leptin and insulin concentrations remained unchanged during the study. In DPD, the plasma leptin concentration increased significantly after CAPD on the first day (PD1) (11.2 +/- 5.4 to 17.0 +/- 6.0 ng/mL, p < 0.05) and this elevation seemed to persist until 7 days after operation. After CAPD, there was no significant day-to-day variation in peritoneal glucose absorption (391-465 cal). Oral intake seemed to decrease on operation day (PD0) and PD1 and then increased slowly. Plasma insulin and glucose concentrations did not significantly change after CAPD. Changes of leptin concentration were significantly correlated with the changes of peritoneal glucose absorption at PD1. In conclusion, continuous peritoneal glucose load may affect plasma leptin concentrations in CAPD patients.