Direct block by bisindolylmaleimide of rat Kv1.5 expressed in Chinese hamster ovary cells

The interaction of bisindolylmaleimide (BIM), widely used as a specific protein kinase C (PKC) inhibitor, with rat brain Kv1.5 (rKv1.5) channels stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. BIM (I) and its inactive analog, BIM (V), inhibited rKv1.5 currents at +50 mV in a reversible concentration-dependent manner with an apparent K(d) value of 0.38 and 1.70 microM, respectively. BIM (I) accelerated the decay rate of inactivation of rKv1.5 currents but did not significantly modify the kinetics of current activation. Other specific PKC inhibitors, chelerythrine and PKC 19-36, had no effect on rKv1.5 and did not prevent the inhibitory effect of BIM (I). The inhibition of rKv1.5 by BIM (I) and BIM (V) was highly voltage-dependent between -30 and 0 mV (voltage range of channel opening), suggesting that both drugs interact preferentially with the open state of the channel. The additional inhibition by BIM (I) displayed a voltage dependence (delta = 0.19) in the full activation voltage range positive to 0 mV, but was not shown in BIM (V) (delta = 0). The rate constants of association and dissociation for BIM (I) were 9.63 microM(-1) s(-1) and 5.82 s(-1), respectively. BIM (I) increased the time constant of deactivation of tail currents from 26. 35 to 45.79 ms, resulting in tail crossover phenomenon. BIM (I) had no effect on the voltage dependence of steady-state inactivation. BIM (I) produced use-dependent inhibition of rKv1.5, which was consistent with the slow recovery from inactivation in the presence of drug. These results suggest that BIM (I) directly inhibits rKv1.5 channels in a phosphorylation-independent, and state-, voltage-, time-, and use-dependent manner.

Use of bioresorbable membrane (sodium hyaluronate + carboxymethylcellulose) after controlled bowel injuries in a rabbit model

PURPOSE

Patients in whom enterolysis is performed are at high risk for recurrence of adhesions and for injury during adhesiolysis. Therefore, the aim of this study was to assess the safety of sodium hyaluronate-based bioresorbable membrane (Seprafilm) after myotomy and enterotomy.

METHODS

A total of 60 rabbits underwent laparotomy with equal distribution to one of three groups: creation of either three repaired, or three unrepaired myotomies, or three repaired enterotomies. Thus, a total of 180 defects were created in the same anatomic positions. One-half of the animals in each group had the surface of the myotomies or enterotomies covered by Seprafilm. Fourteen days later, after complete absorption of Seprafilm, the presence of intra-abdominal abscess, adhesions, and the integrity of the suture line were evaluated by a surgeon blinded to the use of Seprafilm and by a standard radiographic isobaric contrast study. Statistical analysis was done by use of Fisher's exact test; significance was set at P < 0.05.

RESULTS

The incidence of adhesions in the repaired myotomy group were 2 (6.6 percent) and 9 (30 percent) in the Seprafilm and control (nonSeprafilm) groups, respectively (P < 0.05); in the unrepaired myotomy group, 2 (6.6 percent) and 10 (33 percent) in the Seprafilm and control groups, respectively (P < 0.05); and in the enterotomy group, 28 (94 percent) and 29 (97 percent) in the Seprafilm and control groups, respectively (P = not significant). A single phlegmon occurred in the myotomy group at a Seprafilm site (1.6 (1/60) vs. 0 percent, P = not significant). There were no leaks in this group. In the enterotomy group, the incidence of phlegmons was 33 percent (10/30) in the Seprafilm group, whereas it was 27 percent (8/30) in the nonSeprafilm group (P = not significant). The incidence of leaks was 6.6 (2/30) and 10 percent (3/30) in the Seprafilm and nonSeprafilm group, respectively (P = not significant).

CONCLUSION

The use of Seprafilm at the sites of myotomies significantly reduced the incidence of adhesions. Effectiveness at the enterotomy site may have been attenuated by a greater inflammatory response. Importantly, Seprafilm did not increase septic mortality in any group.

Laparoscopic splenectomy for immune thrombocytopenic purpura--long-term result of 40 laparoscopic splenectomies

Laparoscopic surgery has recently extended its indications and it has also become an acceptable surgical approach for splenectomy. In the last five years, we have performed 40 laparoscopic splenectomies for immune thrombocytopenic purpura. Thirty-five patients were female and 5 patients were male. The mean age was 34, varying from 17 to 56. After learning to perform laparoscopic splenectomy with five ports, we are now usually using three or four ports in a right lateral kidney position. There was no case of conversion to exploratory laparotomy. The mean hospital stay was 7 days. There was no perioperative mortality; but in 2 cases we had postoperative subphrenic abscesses which were successfully managed by catheter drainage. Since undergoing laparoscopic splenectomy, 28 patients (70%) were weaned effectively from their steroid medications. Eight patients (20%) have been on small doses of steroid, and 4 patients (10%) have been on the same doses of steroid with no response. The patient group with rapidly increasing platelet count after splenectomy showed a statistically significant relation with the complete response group (p < 0.001). Laparoscopic splenectomy is a safe and reasonable operative procedure for patients with immune thrombocytopenic purpura.

Cadmium inhibits albumin endocytosis in opossum kidney epithelial cells

Chronic exposure to cadmium results in proteinuria. To gain insights into the mechanism by which cadmium inhibits the protein transport in the renal proximal tubule, we investigated the effects of cadmium on the receptor-mediated endocytosis of albumin, using fluorescein isothiocyanate-labeled bovine serum albumin (FITC-albumin) as a model substrate and opossum kidney cell line (OK cell) as a proximal tubular cell model. Cell monolayers grown to confluence were treated with 100 microM CdCl(2) for 60 min at 37 degrees C, washed, and tested for FITC-albumin uptake (37 degrees C) and surface binding (4 degrees C). The amounts of FITC-albumin uptake and binding were quantified by fluorimetrically determining the cell-adherent fluorescence. Both the binding and uptake of FITC-albumin by OK cells appeared to be saturable and inhibitable by unlabeled albumin in the medium, indicating that specific receptor sites were involved. The uptake of FITC-albumin was inhibited by agents that interfere with the formation of endocytotic vesicle (hypertonic mannitol), endosomal acidification (NH(4)Cl), and vesicular trafficking (cytochalasin D and nocodazole), confirming that the uptake occurred via the process of receptor-mediated endocytosis. In cells treated with cadmium, the specific FITC-albumin uptake was significantly attenuated, and this was due to a reduction in V(max) and a rise in K(m). These changes in kinetic parameters were similar to those induced by NH(4)Cl. The binding of FITC-albumin to the apical surface of OK cells was inhibited by cadmium treatment, and this was attributed to a reduction in B(max). The values of K(d) and its pH dependency were not altered by cadmium treatment. The formation of endocytotic vesicles, as judged by fluid phase endocytosis of FITC-inulin, was not changed by cadmium treatment. These results indicate that the receptor-mediated endocytosis of albumin is impaired in cadmium-treated OK cells most likely due to a defect in endosomal acidification and the attendant fall in ligand-receptor dissociation, which impairs receptor recycling and the overall efficiency of endocytosis.

Effect of resection velocity and suction ring on corneal flap formation in laser in situ keratomileusis

PURPOSE

To determine the effects of microkeratome-cutting velocities and the suction ring on corneal flap creation.

SETTING

Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea.

METHODS

Procedures were performed under clinical settings in 65 pig eyes. Keratometric diopters (D) were measured before and after application of the suction ring. Corneal thickness was measured before and after resection cutting, and the difference was taken as flap thickness. The microkeratome was initially set at a resection thickness of 160 microns. The blade oscillation (turbine velocity) was set at 30, 35, and 42 psi. The translational velocity was arbitrarily divided into high (1 to 2 seconds), moderate (3 to 5 seconds), and low (6 seconds or more). Data were analyzed by varying the velocities consecutively. Photographs of the cut surface were acquired by scanning electron microscopy to evaluate resection morphology by comparison.

RESULTS

Mean refractive powers were 39.94 D +/- 0.66 (SD) and 39.69 +/- 0.98 D before and after application of the suction ring, respectively; however, no significant difference was observed (P = .216). Lower surgeon translational velocity resulted in a significantly thicker corneal flap in 8 of the 9 paired comparisons (P < .05). Higher turbine velocity resulted in a significantly thicker corneal flap in 7 of the 9 paired comparisons (P < .05). The cut surface was smoother at higher turbine and lower translational velocity. The initial cut margin was steeper at higher translational velocity.

CONCLUSIONS

The increase in intraocular pressure induced by the suction ring had no significant effect on keratometric power. At higher turbine and lower translational velocities, the corneal flap was thicker and the cut surface smoother. Higher translational velocities made the initial cut margin steeper.

Characterization of a targeted gene carrier, lactose-polyethylene glycol-grafted poly-L-lysine and its complex with plasmid DNA

The physicochemical properties and gene transfer ability of lactose-polyethylene glycol-grafted poly-L-lysine (Lac-PEG-PLL) were investigated. A dye displacement assay showed that plasmid DNA self-assembled with Lac-PEG-PLL, and condensation began at a <1:1 charge ratio of plasmid DNA to polymer. In atomic force microscopy, spontaneously assembled Lac-PEG-PLL/DNA complexes revealed a compact structure, with a size of about 100-200 nm. Circular dichroism spectra of Lac-PEG-PLL/DNA complexes revealed that the secondary structure of DNA was altered by complex formation and was similar to that of the poly-L-lysine/DNA complex. Lac-PEG-PLL was shown to protect DNA against nuclease action in a DNase I protection assay. The cytotoxicity test demonstrated that the complex composed of plasmid DNA and Lac-PEG-PLL had little influence on the viability of HepG2 cells, especially in comparison with that of poly-L-lysine/DNA complexes. In conclusion, our copolymer, Lac-PEG-PLI, formed complexes with plasmid DNA (on average, 150 nm), gave little cytotoxicity, and showed increased efficiency of gene transfer into hepatoma cells in vitro. Lactose-polyethylene glycol was grafted to poly-L-lysine to be used as a gene carrier for hepatoma cell targeting and to improve the solubility of the polyplexes. The average size of the carrier/DNA complexes was about 150 nm. The complexes also proved to have high resistance against nuclease attack and little cytotoxicity. The polymer also delivered plasmid DNA efficiently into a HepG2 cell line. Lac-PEG-PLL was more efficient than Lipofectin or galactose-PEG-PLL in transfection efficiency.

Administration-time differences in the pharmacokinetics of gentamicin intravenously delivered to human beings

Administration-time differences of gentamicin pharmacokinetics were studied by crossover design after a single intravenous administration of gentamicin (80 mg) to 10 human subjects at 09:00 (morning time) and 22:00 (nighttime). The profiles of serum gentamicin concentration showed a significant statistical difference between 09:00 and 22:00, suggesting circadian variations of pharmacokinetic behaviors. A significant circadian rhythm of pharmacokinetic parameters as a function of time of day was noted in human subjects, showing lower total body clearance Clt and higher serum area under the curve (AUC) when given at nighttime. The half-life t1/2 was shorter in the morning (2.82 h +/- 0.43 h) when compared to the nighttime (2.97 h +/- 0.36 h), but the difference was not statistically significant. The AUC was significantly greater in the morning (23.4 +/- 3.84 micrograms-h/mL) than that in the nighttime (26.3 +/- 5.79 micrograms-h/mL) (p < .05), most likely because the Clt was significantly higher when gentamicin was given in the morning (3.51 +/- 0.57 L/h) versus in the nighttime (3.18 +/- 0.65 L/h). Although the volume of distribution Vd decreased when given at nighttime, it was independent of the dosing time. From this study, there was an administration-time difference of gentamicin pharmacokinetics in human beings. The optimized dosing regimen of gentamicin can be decided by considering circadian rhythm and rest-activity routine so that minimized toxicity and effective therapy are established for patients. The current findings also can be applied to other drugs with circadian rhythms of pharmacokinetics and narrow therapeutic windows in clinical chronotherapeutics.

Enhanced secretory group II PLA2 activity in the tears of chronic blepharitis patients

PURPOSE

Phospholipase A2 (PLA2) hydrolyzes phospholipids, one of the important constituents of human meibomian gland secretions. This study was performed to investigate PLA2 type and activity in the tears of chronic blepharitis patients compared to those of normal persons.

METHODS

Tear samples of 36 patients and 10 normal persons were collected in non-heparinized microcapillary tubes. PLA2 activity in the tears was measured by Dole's method, and the results of the blepharitis patients were compared to those of the normal persons. The characterization of PLA2 was performed by the head group preference test and the dithiothreitol (DTT) sensitivity test. The classification of PLA2 type was done using Western blot analysis with anti-human secretory PLA2 antibody.

RESULTS

No statistically significant differences were found among the six categories of chronic blepharitis. However, the mean PLA2 activity in the tears of the chronic blepharitis patients was about two times higher than that of the normal controls with statistical significance (P < 0.05). The PLA2 substrate specificity test revealed group II PLA2 activity. Furthermore, the group II PLA2 was identified as a 14 kDa band in Western blot analysis using an antibody raised against human secretory group II PLA2.

CONCLUSIONS

Secretory group II PLA2 activity was significantly enhanced in the tears of the chronic blepharitis patients compared with that of the normal controls. It is suggested that this increased enzymatic activity may decrease the tear film stability through increased hydrolysis of phospholipids.

Mechanism of fluoxetine block of cloned voltage-activated potassium channel Kv1.3

The effects of fluoxetine (Prozac), a widely used antidepressant drug, on Kv1.3 stably expressed in Chinese hamster ovary cells were examined using the whole-cell and excised inside-out configurations of the patch-clamp technique. In whole-cell recordings, fluoxetine accelerated the decay rate of inactivation of Kv1.3 and thus decreased the current amplitude at the end of the pulse in a concentration-dependent manner with an IC(50) value of 5.9 microM. The inhibition displayed a weak voltage dependence, increasing at more positive potentials. Neither the activation nor the steady-state inactivation curve was affected by fluoxetine. In addition, fluoxetine reduced the tail current amplitude and slowed the deactivation of the tail current, resulting in a crossover phenomenon. When applied to the internal side of the membrane in inside-out recordings, the inhibition by fluoxetine was much faster and more potent with an IC(50) value of 1.7 microM compared with whole-cell recordings. Norfluoxetine, the major metabolite of fluoxetine, also inhibited Kv1.3 in a concentration-dependent manner (IC(50) = 1.4 microM) in whole-cell recordings. To check whether the fluoxetine-induced inhibition demonstrated in cloned Kv1.3 could also be observed in native T lymphocytes, the effects of fluoxetine were investigated on human T lymphocytes. Fluoxetine also inhibited outward K(+) current in human T lymphocytes. Our results indicate that fluoxetine produced a concentration- and voltage-dependent inhibition of Kv1.3 that can be interpreted as an open channel block and that a binding site for fluoxetine is more accessible from the intracellular side.

Influence of 5,10-methylenetetrahydrofolate reductase gene polymorphism on plasma homocysteine concentration in patients with end-stage renal disease

The purpose of this study is to observe the influence of the methylenetetrahydrofolate reductase (MTHFR) gene (677C-->T substitution) on plasma homocysteine levels in end-stage renal disease (ESRD) patients who received a relatively large amount of folate (2 mg/d) and are undergoing hemodialysis. A cross-sectional study of plasma homocysteine, vitamin B(12), and folate was performed in patients with ESRD. The study population for the MTHFR gene study included 312 healthy subjects and 106 patients with ESRD undergoing hemodialysis. The C677T transition in the MTHFR gene was detected by HinF 1 restriction enzyme analysis and subsequent electrophoresis in a 3% agarose gel. The genotype of the MTHFR gene in 106 patients with ESRD was homozygous C677T mutation (VV) in 17 patients (16.1%) and heterozygous (AV) in 63 patients (58.4%); 26 patients (24.5%) did not carry this mutation (AA). The mean levels of homocysteine, vitamin B(12), and folate in the patients with ESRD were 23.3 +/- 14.0 mmol/L, 620.2 +/- 98.5 pmol/L, and 138.6 +/- 55.6 nmol/L, respectively. There was no significant difference in homocysteine levels among the three genotypes: 28.2 +/- 19.4 mmol/L for VV, 22.7 +/- 14.9 mmol/L for AV, and 23.4 +/- 11.1 mmol/L for AA genotype (P > 0.05). There was no difference in genotype distribution between the patient groups of less than 25th and greater than 75th percentiles, classified according to plasma homocysteine levels (P = 0.47). In conclusion, with high-dose folate supplementation, the hyperhomocysteinemia in patients with ESRD does not seem to be caused by the 677C-->T mutation in the MTHFR gene.

Identification of acylated glycoglycerolipids from a cyanobacterium, Synechocystis sp., by tandem mass spectrometry

Acylated glycoglycerolipids were identified in the total lipid extract from cyanobacterium Synechocystis sp. PCC 6803. These compounds have a palmitoyl group esterified to the hydroxyl group at the C-6 position of the terminal glycosyl moiety of digalactosyl monoacylglycerol and digalactosyl diacylglycerol. Their structural elucidation was accomplished by tandem mass spectrometry coupled with fast atom bombardment ionization. Acylated digalactosyl monoacylglycerol has a structure of 1-hydroxy-2-palmitoyl-3-O-[(6-O-palmitoyl)-alpha-D-galactopyranosyl -(1-->6)-beta-D-galactopyranosyl]-sn-glycerol. This compound has not been reported previously.

Imported tertian malaria resistant to primaquine

In Plasmodium vivax and Plasmodium ovale malaria, some of the liver stage parasites remain dormant. The activation of these dormant forms (called hypnozoite) can give rise to relapse weeks, months or years after the initial infection. To prevent relapses, a course of primaquine may be given as terminal prophylaxis to patients. Different strains of Plasmodium vivax vary in their sensitivity to primaquine and, recently, cases of relapse of Plasmodium vivax after this standard primaquine therapy were reported from various countries. We reported a case of primaquine resistant malaria which initially was thought to be relapsed caused by loss of terminal prophylaxis.

Photomovement of the gliding cyanobacterium Synechocystis sp. PCC 6803

Using a computerized videomicroscope motion analysis system, we investigated the photomovements of two Synechocystis sp. (PCC 6803 and ATCC 27184). Synechocystis sp. PCC 6803 displays a relatively slow gliding motion. The phototactic and photokinetic speeds of this cyanobacterium in liquid media were 5 microns/min and 15.8 microns/min, respectively, at 3 mumol/m2/s of stimulant white light. Synechocystis sp. PCC 6803 senses light direction rather than intensity for phototaxis. Synechocystis sp. ATCC 27184 showed a weak photokinesis but no phototaxis. Analysis of Synechocystis sp. ATCC 27184 suggests that the loss of phototaxis results from spontaneous mutation during several years of subculture. When directional irradiation was applied, the cell population of Synechocystis sp. PCC 6803 began to deviate from random movement and reached maximum orientation at 5 min after the onset of stimulant white light. Synechocystis sp. PCC 6803 showed high sensitivity to the stimulant white light of fluence rates as low as 0.002 mumol/m2/s. Neither 1,3-dichlorophenyldimethyl urea nor cyanide affected phototactic orientation, whereas cyanide inhibited gliding speed. This result suggests that the phototaxis of Synechocystis sp. PCC 6803 is independent of photosynthetic phosphorylation and that its gliding movement is primarily powered by oxidative phosphorylation. In the visible wavelength region, 560 nm, 660 nm and even 760 nm caused positive phototaxis. However, 360 nm light induced strikingly negative phototaxis. Therefore, at least two independent photoreceptors may exist to control phototaxis. The photoreceptor for positive phototaxis appears likely to be a phytochrome-like tetrapyrrole rather than chlorophyll a.

Inhibitory effect of luteolin 4'-O-glucoside from Kummerowia striata and other flavonoids on interleukin-5 bioactivity

Interleukin (IL)-5 is a chemotactic factor of eosinophils, and promotes the growth and survival of eosinophils, which plays an important role in the eosinophilia-associated allergic inflammation. In this study, luteolin 4'-O-glucopyranoside was identified as the IL-5 inhibitor from Kummerowia striata Thunb. (Leguminosae) by activity-guided fractionation followed by structural analysis compared with reported spectral data. The flavone compound exhibited dose-dependent inhibitory effect on IL-5 bioactivity with 95% inhibition at 30 microM, 79% at 15 microM, 60% at 7.5 microM, 54% at 3.8 microM and 29% at 1.9 microM, where 50% of inhibition (IC50) value was shown at the concentration of 3.7 microM. Furthermore, the inhibitory effect on IL-5 bioactivity by other flavonoid compounds available was estimated. In view of the IC50 values, the inhibitory potency on IL-5 bioactivity was in order of luteolin 4'-O-glucopyranoside > cosmosiin (14.2 microM) approximately equal to apigenin (16.4 microM) approximately equal to luteolin (18.7 microM) > quercimeritrin (27.3 microM) approximately equal to kaempferol (30.0 microM).

In vivo experiment leading to clinical application of an electrohydraulic ventricular assist device with magnetic coupling

We developed an electrohydraulic ventricular assist device with magnetic coupling. The integrated system consists of a blood pump, a water conduit for pressure transmission, a bellows type pumping sac, an actuator for transforming the circular motion of a motor to the linear motion of a pusher plate attached to the pumping sac with magnetic coupling, and a controller. The purpose of the coupling was to prevent excessive sucking against the atrial wall. Number 21 Medtronic Hall (Irvine, CA) mechanical valves were used in the inflow and outflow ports of the blood pump. Maximum dynamic stroke volume was 48 ml, and against a mean afterload of 100 mm Hg, maximum pump output was 7 L/min. Chronic in vivo experiments were performed in three sheep, and during these evaluations the system showed no noticeable problems related to mechanical or electronic devices. When left atrial pressure decreased below 0 mm Hg, the magnetic coupling system decoupled the pumping sac and pusher plate with satisfactory reliability. The device was clinically applied in a postoperative patient with chronic dilating cardiomyopathy, and no significant device related problems ensued. These results prove that the electrohydraulic ventricular assist system with magnetic coupling is a suitable ventricular assist device.

Staurosporine directly blocks Kv1.3 channels expressed in Chinese hamster ovary cells

The effects of staurosporine (ST), a widely used protein kinase C (PKC) inhibitor, were examined on Kv1.3 channels stably expressed in Chinese hamster ovary (CHO) cells using the whole-cell and excised inside-out configurations of the patch clamp technique. In whole-cell recordings, ST, at external concentrations from 300 nM to 10 microM, accelerated the rate of inactivation of Kv1.3 currents and thereby reduced the current at the end of the depolarizing pulse in a concentration-dependent manner with an IC50 of 1.2 microM. The actions of ST were unaffected by pretreatment with another selective PKC inhibitor, chelerythrine, or by including the PKC pseudosubstrate peptide inhibitor, PKC 19-36, in the intracellular solution. Rp-cAMPS, a specific protein kinase A inhibitor, included in intracellular solution did not affect the effects of ST. Furthermore, the same effects of ST on Kv1.3 were also observed in excised inside-out patches when applied to the internal face of the membrane. These effects were completely reversible upon washing. Current-voltage relations for Kv1.3 currents at the end of voltage steps indicated that ST reduced Kv1.3 currents over a wide voltage range. The blockade exhibited a shallow voltage dependence between -10 mV and +40 mV, increasing at more positive potentials. ST had no effect on the voltage dependence of steady-state inactivation. It reduced the tail current amplitude and slowed the deactivation time course, resulting in a crossover phenomenon. These results suggest that the action of ST on Kv1.3 is independent of PKC and PKA inhibition. ST blocks the open state of Kv1.3 channels to produce an apparent acceleration of the inactivation rate.

Reactive oxygen species-induced apoptosis and necrosis in bovine corneal endothelial cells

PURPOSE

The loss of corneal endothelial cells associated with aging and possibly other causes has been speculated to be related to exposure to reactive oxygen species (ROS). The current study was conducted to investigate, by use of photosensitizers, the underlying mechanisms involved in the death of bovine corneal endothelial cells (BCENs) caused by ROS.

METHODS

BCEN cells in primary culture were treated with a photosensitizer (riboflavin or rose bengal) with light exposure. The patterns of cell damage and death were assessed using an acridine orange-ethidium bromide differential staining method, TdT-mediated dUTP nick-end labeling (TUNEL) assay, and transmission electron microscopy. The cytotoxicity was assayed by mitochondrial function using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) testing. Antioxidants, including catalase, L-histidine, salicylic acid, and superoxide dismutase, were used to determine the types of ROS involved. Activation of nuclear factor (NF)-kappaB was examined by fluorescent immunocytochemistry with anti-p65 antibody.

RESULTS

Light-irradiated riboflavin or rose bengal resulted in a significant decrease in viability of BCEN cells. Chromosomal condensation and fragmentation were observed in apoptotic cells, and membrane lysis and damage of cell ultrastructures were observed in necrotic cells. Riboflavin induced apoptosis at 30 minutes and thereafter and induced necrosis after 2 hours. Rose bengal was shown to cause similar effects within half the time required for the effects of riboflavin. Catalase and salicylic acid were found to provide protection for BCENs from cytotoxic effects of riboflavin, and L-histidine was found to protect BCENs from cytotoxicity induced by rose bengal. Kinetic studies using immunocytochemistry showed that NF-kappaB was translocated into the nucleus within 15 minutes and 30 minutes after treatment with rose bengal and riboflavin, respectively.

CONCLUSIONS

The cytotoxic effects of photo-irradiated riboflavin and rose bengal are shown to be mediated by two distinct but parallel pathways, one leading to apoptosis and the other to necrosis. Possible involvement of NF-kappaB in cell death is suggested. These findings provide potential leads for future investigation into the molecular mechanisms of loss of corneal endothelial cells related to aging, oxidative stress, and possibly other similar causes.

Antioxidant flavonoids and chlorogenic acid from the leaves of Eriobotrya japonica

The antioxidant activity of Eriobotrya japonica was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl) radical and lipid peroxidation produced when mouse liver homogenate was exposed to the air at 37 degrees C, using 2-thiobarbituric acid (TBA). The methanol extract and its fractions of Eriobotrya japonica leaves showed strong antioxidant activity. The antioxidant activity of EtOAc and n-BuOH soluble fractions were stronger than the others, and were further purified by repeated silica gel, MCl gel CHP-20P, and Sephadex LH-20 column chromatography. Antioxidant chlorogenic acid, quercetin-3-sambubioside from n-BuOH fraction, and methyl chlorogenate, kaempferol- and quercetin-3-rhamnosides, together with the inactive ursolic acid and 2 alpha-hydroxyursolic acid from EtOAc fraction were isolated. Antioxidant flavonoids and chlorogenic acid also showed prominent inhibitory activity against free radical generation in dichlorofluorescein (DCF) method.

Improved cycle sequencing of GC-rich DNA template

Even when DNA sequencing of purified DNA template failed under the optimal condition, it can be generally contributed to high GC content. GC-rich region of template causes a secondary structure to produce shorter readable sequence. To solve this problem, the sequencing reaction was modified by using dimethyl sulfoxide (DMSO). It was found that 5% (v/v) of DMSO in the reaction mixture recovers sequencing signal intensity with reduced frequency of ambiguous bases. When DMSO was added to sequencing reaction of DNA template with normal GC content, it did not show any adverse effect. Sequencing accuracy and unambiguous base frequency were significantly improved at concentration of 2% to 5% (v/v) DMSO in GC-rich DNA template. DMSO has been empirically introduced to enhance the efficiency of PCR in GC-rich templates. However, the underlying mechanism of improved cycle sequencing by DMSO is unknown. Thus, cycle sequencing reaction was remodified with other additives such as N-methyl imidazole, N-methyl2-pyrrolidone, N-methyl-2-pyridone and glycerol, possessing the similar chemical properties as DMSO. Most of methyl nitrogen ring-containing chemicals did not improve sequencing accuracy, whereas only glycerol mimicked the positive effect of DMSO by the same extent. In the present study, we suggest that the treatment of DMSO improve cycle sequencing by the alteration of structural conformation of GC-rich DNA template.

Necrosis and apoptosis after retinal ischemia: involvement of NMDA-mediated excitotoxicity and p53

PURPOSE

Accumulated evidence has shown that apoptosis and necrosis contribute to neuronal death after ischemia. The present study was performed to study the temporal and spatial patterns of neuronal necrosis and apoptosis after ischemia in retina and to outline mechanisms underlying necrosis and apoptosis.

METHODS

Retinal ischemia was induced by increasing intraocular pressure to a range of 160 mm Hg to 180 mm Hg for 90 minutes in adult rats. The patterns of neuronal cell death were determined using light and electron microscopy and were visualized by TdT-dUTP nick-end labeling (TUNEL). The mRNA expression profile of p53 was examined using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization histochemistry. Immunohistochemistry was performed using anti-p53, anti-microtubule associated protein-2, and anti-glial fibrillary acidic protein antibodies.

RESULTS

Within 4 hours after ischemia, neurons in the inner nuclear cell layer (INL) and ganglion cell layer (GCL) underwent marked necrosis, made apparent by swelling of the cell body and mitochondria, early fenestration of the plasma membrane, and irregularly scattered condensation of nuclear chromatin. After 3 days, the INL and GCL neurons showed further degeneration through apoptosis marked by cell body shrinkage, aggregation, and condensation of nuclear chromatin. Apoptotic neurons were also observed sparsely in the outer nuclear cell layer. Intravitreal injections of MK-801 prevented early neuronal degeneration after ischemia. Of note, mRNA and protein levels of p53, the tumor suppressor gene known to induce apoptosis, were increased in the retinal areas undergoing apoptosis 1 to 3 days after ischemic injury.

CONCLUSIONS

Ischemia produces the N-methyl-D-aspartate-mediated necrosis and slowly evolving apoptosis of neurons in the retina. The latter may depend on the expression of the p53 proapoptosis gene.

Structural identification of glycerolipid molecular species isolated from cyanobacterium Synechocystis sp. PCC 6803 using fast atom bombardment tandem mass spectrometry

Our previous works have demonstrated that fast atom bombardment tandem mass spectrometry can be a valuable tool in determining the complete structure of glycoglycerolipids and glycerophospholipids. Collision-induced dissociation of sodium-adducted molecular ions ([M + Na]+ or [M - H + 2Na]+) generates diverse product ions informative on the double-bond position in fatty acyl groups as well as the polar head group and fatty acid composition. Here we report that this direct and rapid method can be applied to the structural determination of individual molecular species of each glycerolipid class purified from the total lipid extract of cyanobacterium Synechocystis sp. PCC 6803. Especially, based on the preference for the loss of the fatty acyl group positioned at the sn-2, it was proved that all of the molecular species of diacylglycerolipids contained a palmitoyl group exclusively at the sn-2 position. Additionally, lysoglycerolipids, monoacyl forms of four major membrane diacylglycerolipids, were first isolated together from a fresh extract. Using fast atom bombardment mass spectrometry and tandem mass spectrometry, it was found that each lysoglycerolipid had a molecular species with only palmitic acid as a fatty acyl group. Thus, these compounds could be synthesized by specific enzyme-catalyzed hydrolysis of the sn-1 fatty acyl group of the corresponding diacylglycerolipids.

Inhibition by fluoxetine of voltage-activated ion channels in rat PC12 cells

The effects of fluoxetine (Prozac) on voltage-activated K+, Ca2+ and Na+ channels were examined using the whole-cell configuration of the patch clamp technique in rat pheochromocytoma (PC12) cells. When applied to the external bath solution, fluoxetine (1, 10, 100 microM) decreased the peak amplitude of K+ currents. The K+ current inhibition by fluoxetine (10 microM) was voltage-independent and the fraction of current inhibition was 39.7-51.3% at all voltages tested (0 to +50 mV). Neither the activation and inactivation curves nor the reversal potential for K+ currents was significantly changed by fluoxetine. The inhibition by fluoxetine of K+ currents was use- and concentration-dependent with an IC50 of 16.0 microM. The inhibition was partially reversible upon washout of fluoxetine. The action of fluoxetine was independent of the protein kinases, because the protein kinase C or A inhibitors (H-7, staurosporine, Rp-cAMPS) did not prevent the inhibition by fluoxetine. Intracellular infusion with GDPbetaS or pretreatment with pertussis toxin did not block the inhibitory effects of fluoxetine. The inhibitory action of fluoxetine was not specific to K+ currents because it also inhibited both Ca2+ (IC50 = 13.4 microM) and Na+ (IC50 = 25.6 microM) currents in a concentration-dependent manner. Our data indicate that when applied to the external side of cells, fluoxetine inhibited voltage-activated K+, Ca2+ and Na+ currents in PC12 cells and its action on K+ currents does not appear to be mediated through protein kinases or G proteins.

Poly(ethylene glycol)-block-poly(L-lysine) dendrimer: novel linear polymer/dendrimer block copolymer forming a spherical water-soluble polyionic complex with DNA

Methoxypoly(ethylene glycol)-block-poly(L-lysine) dendrimer was designed to form a water-soluble complex with plasmid DNA. The copolymer was synthesized by the liquid-phase peptide synthesis method. It was characterized by 1H NMR and matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrum. Agarose gel electrophoresis and DNase I protection assay proved that this linear polymer/dendrimer block copolymer assembled spontaneously with plasmid DNA, forming a water-soluble complex which increased the stability of the complexed DNA. Atomic force microscopy of the complex was evaluated at various charge ratios showing that the copolymer/DNA complex was like a globular shape.

Circadian changes in pharmacokinetics of cyclosporin in healthy volunteers

Circadian changes in the pharmacokinetics of cyclosporin were evaluated after oral administration of the drug, 300 mg, at 09:00 and 20:00 to twelve healthy male subjects. At 09:00, the blood concentrations of cyclosporin were higher, the area under the blood concentration-time curve from time 0 to time infinity was significantly greater (9.70 versus 8.42 microg x hr/ml), and the renal clearance was significantly slower (1.14 versus 1.48 ml/min) than those at 22:00. The terminal half-life, peak concentration, and time to reach peak concentration were not significantly different between two groups.

In vitro angiogenic activity of Aloe vera gel on calf pulmonary artery endothelial (CPAE) cells

Angiogenic activity of Aloe vera gel was investigated by in vitro assay. We obtained the most active fraction from dichloromethane extract of Aloe vera gel by partitioning between hexane and 90% aqueous methanol. The most active fraction (F3) increased the proliferation of calf pulmonary artery endothelial (CPAE) cells. In addition, F3 fraction induced CPAE cells to invade type 1 collagen gel and form capillary-like tube through in vitro angiogenesis assay, and increased the invasion of CPAE cells into matrigel through in vitro invasion assay. Furthermore, the effect on the mRNA expression of proteolytic enzymes which are key participants in the regulation of extracellular matrix degradation was investigated by northern blot analysis. F3 fraction enhanced mRNA expression of urokinase-type plasminogen activator (u-PA), matrix metalloproteinase-2 (MMP-2), and membrane-type MMP (MT-MMP) in CPAE cells whereas the expression of plasminogen activator inhibitor-1 (PAI-1) mRNA was not changed.