Biological effects of blood–brain barrier disruption using a focused ultrasound

With focused ultrasound (FUS) and microbubbles, BBB can be transiently disrupted with a localized and non-invasive approach. BBB disruption induced by FUS has made progressions to move forward on delivery of therapeutic agents into a brain in a specific area of brain for better treatment of neurological diseases. In addition to be used as an improvement of drug delivery, BBB disruption has been found to induce biological effects such as a clearance of protein aggregation which cause Alzheimer's disease, regulation of proteins which facilitate drug uptake, and modulation of neuronal function and neurogenesis. In this review, we discuss overview about the principles of BBB opening with FUS and milestones in these biological effects of FUS-induced BBB disruption.

5-(4-Hydroxy-2,3,5-trimethylbenzylidene) thiazolidine-2,4-dione attenuates atherosclerosis possibly by reducing monocyte recruitment to the lesion

A variety of benzylidenethiazole analogs have been demonstrated to inhibit 5-lipoxygenase (5-LOX). Here we report the anti-atherogenic potential of 5-(4-hydroxy-2,3,5-trimethylbenzylidene) thiazolidin-2,4-dione (HMB-TZD), a benzylidenethiazole analog, and its potential mechanism of action in LDL receptor-deficient (Ldlr-/-) mice. HMB-TZD Treatment reduced leukotriene B4 (LTB4) production significantly in RAW264.7 macrophages and SVEC4-10 endothelial cells. Macrophages or endothelial cells pre-incubated with HMB-TZD for 2 h and then stimulated with lipopolysaccharide or tumor necrosis factor-alpha (TNF-alpha) displayed reduced cytokine production. Also, HMB-TZD reduced cell migration and adhesion in accordance with decreased proinflammatory molecule production in vitro and ex vivo. HMB-TZD treatment of 8-week-old male Ldlr-/- mice resulted in significantly reduced atherosclerotic lesions without a change to plasma lipid profiles. Moreover, aortic expression of pro-atherogenic molecules involved in the recruitment of monocytes to the aortic wall, including TNF-alpha , MCP-1, and VCAM-1, was downregulated. HMB-TZD also reduced macrophage infiltration into atherosclerotic lesions. In conclusion, HMB-TZD ameliorates atherosclerotic lesion formation possibly by reducing the expression of proinflammatory molecules and monocyte/macrophage recruitment to the lesion. These results suggest that HMB-TZD, and benzylidenethiazole analogs in general, may have therapeutic potential as treatments for atherosclerosis.

Mechanisms of Selective Antimicrobial Activity of Gaegurin 4

Gaegurin 4 (GGN4), an antimicrobial peptide isolated from a Korean frog, is five times more potent against Gram-positive than Gram-negative bacteria, but has little hemolytic activity. To understand the mechanism of such cell selectivity, we examined GGN4-induced K+ efflux from target cells, and membrane conductances in planar lipid bilayers. The K+ efflux from Gram-positive M. luteus (2.5microgram/ml) was faster and larger than that from Gram-negative E. coli (75microgram/ml), while that from RBC was negligible even at higher concentration (100microgram/ml). GGN4 induced larger conductances in the planar bilayers which were formed with lipids extracted from Gram-positive B. subtilis than in those from E. coli (p<0.01), however, the effects of GGN4 were not selective in the bilayers formed with lipids from E. coli and red blood cells. Addition of an acidic phospholipid, phosphatidylserine to planar bilayers increased the GGN4-induced membrane conductance (p<0.05), but addition of phosphatidylcholine or cholesterol reduced it (p<0.05). Transmission electron microscopy revealed that GGN4 induced pore-like damages in M. luteus and dis-layering damages on the outer wall of E. coli. Taken together, the present results indicate that the selectivity of GGN4 toward Gram-positive over Gram-negative bacteria is due to negative surface charges, and interaction of GGN4 with outer walls. The selectivity toward bacteria over RBC is due to the presence of phosphatidylcholine and cholesterol, and the trans-bilayer lipid asymmetry in RBC. The results suggest that design of selective antimicrobial peptides should be based on the composition and topology of membrane lipids in the target cells.

Development of immunoassays for the detection of kanamycin in veterinary fields

Monoclonal antibody against kanamycin was prepared, and competitive direct ELISA and immunochromatographic assay were developed using the antibody to detect kanamycin in animal plasma and milk. The monoclonal antibody produced was identified to be IgG1, which has a kappa light chain. No cross-reactivity of the antibody was detected with other aminoglycosides, indicating that the monoclonal antibody was highly specific for kanamycin. Based on competitive direct ELISA, the detection limits of kanamycin were determined to be 1.1 ng/ml in PBS, 1.4 ng/ml in plasma, and 1.0 ng/ml in milk. The concentration of intramuscularly injected kanamycin was successfully monitored in rabbit plasma with competitive direct ELISA. Based on the colloidal gold-based immunochromatographic assay, the detection limits of kanamycin were estimated to be about 6-8 ng/ml in PBS, plasma, and milk. The immunochromatographic assay would be suitable for rapid and simple screening of kanamycin residues in veterinary medicine. Screened positives can be confirmed using a more sensitive laboratory method such as competitive direct ELISA. Therefore, the assays developed in this study could be used to complement each other as well as other laboratory findings. Moreover, instead of slaughtering the animals to obtain test samples, these methods could be applied to determine kanamycin concentration in the plasma of live animals.

Genotoxicity and toxicological effects of acrylamide on reproductive system in male rats

The toxicity of acrylamide was evaluated through mutagenicity of Salmonella, chromosome aberration of Chinese hamster lung fibroblasts, micronucleus formation in mice and reproductive toxicity in rats. Based on Ames test, acrylamide showed mutagenic potency for strains TA98 and TA100. Moreover, both chromosomal aberration assay and micronucleus assay indicated that acrylamide might have genotoxic potency; the chromosomal aberration frequencies were observed to be proportional to acrylamide concentrations of 5-50 mM, and acrylamide significantly increased micronuclei in peripheral blood cells of mice at doses of higher than 72.5 mg/kg. Male rats were treated with acrylamide at doses of 0, 5, 15, 30, 45, or 60 mg/kg/day for 5 consecutive days, and the toxicity of acrylamide was observed. In the group treated with the highest dose of acrylamide (60 mg/kg/day), the loss of body weight and reduced testis weight were observed. Also the epididymides weights were reduced significantly in all the groups treated with acrylamide. The number of sperms in cauda epididymidis decreased significantly in an acrylamide dose-dependent manner. Rats treated with 60 mg/kg/day of acrylamide showed several histopathological lesions in the seminiferous tubules. There were thickening and multiple layering of the tubular endothelium, and the formation of many multinucleated giant cells in seminiferous tubules. Taken together, acrylamide not only causes the genotoxicity of eukaryotic cells and mice but also shows the toxicological effects on reproductive system in male rats.

Topology of Scavenger Receptor Class B Type I (SR-BI) on Brush Border Membrane

Both hydropathy plot and in vitro translation results predict the topology of SR-BI; the receptor is an integral membrane protein of 509 amino acids, consisting of a short cytoplasmic N-terminus of 9 amino acids followed by a first transmembrane domain of 22 amino acids, the extracellular domain of 408 amino acids, the second transmembrane domain of 22 amino acids, and the cytoplasmic C-terminus of 47 amino acids. The immunoblot of rBBMV in the presence or absence of pAb589 peptide antigen (the C-terminal 22 amino acid residues of SR-BI) confirmed that the bands at apparent molecular weight of 140 and 210 kDa are SR-BI related protein which might be multimeric forms of SR-BI. 125I apo A-I overlay analysis showed that SR-BI can bind to its ligand, apo A-I, only when it is thoroughly matured - glycosylated and dimerized. The antibody which was generated against extracellular domain of SR-BI (pAb230) not only prevented 125I-labeled apo A-I from binding to 140 kDa band but also inhibited the esterified cholesterol uptake of rabbit BBMV with its IC50 value of 40 microgram/ml of IgG. In contrast, the antibody generated against the C-terminal domain of SR-BI (pAb589) did not show any effect either on cholesterol uptake of rabbit BBMV or 125I-labeled apo A-I binding to 140 kDa band. Overall results show that the ligand binding site of SR-BI in rabbit BBMV is located in extracellular domain, and SR-BI is only functional when it is part of dimeric forms which rationalize the previously found cooperative nature of the binding interaction and maybe a fundamental finding towards the so far poorly understood mechanism of SR-BI function.

Expression of ATP-sensitive potassium channel and sulfonylurea receptor in neonate and adult rat tissues

The ATP-sensitive potassium (KATP) channel is a member of inward rectifier potassium channel (Kir) that is inhibited by intracellular ATP and functions in close relation to sulfonylurea receptors (SUR). Although the molecular mechanism and physiological function of KATP channels are well understood, the expression pattern during development or treatment with the channel modulators such as glybenclamide is little known. In this work, we determined mRNA levels of a KATP channel (Kir6.2) and a sulfonylurea receptor (SUR2) in rat tissues by RNase protection assay. Levels of Kir6.2 and SUR2 mRNA in the rat brain and skeletal muscle were higher in adult (90-120 days) than in neonate (2-8 days), whereas those in the heart were not much different between neonate (2-8 days) and adult (90-120 days). In addition, none of KATP channel modulators (opener, pinacidil and nicorandil; blocker, glybenclamide) affected the Kir6.2 mRNA levels in the heart, brain and skeletal muscle. The results indicate that the expression of Kir and SUR genes can vary age-dependently, but the expression of Kir is not dependent on the long-term treatment of channel modulators. The effect of the channel modulators on mRNA level of SUR is remained to be studied further.

Establishing Web-Based Birth Defects Monitoring Systems in Incheon / 대한의료정보학회지

Problems of birth defects and low birth weight are important issues of public health because most infant mortality are caused by these two. To discover the etiology of birth defects and low birth weight, it is necessary to establish epidemiological birth defects monitoring system in Korea. With the rapid growing of internet usage in korea, the computer network has become the popular means of communicating and sharing of information. Our aim was to develop web-based reporting and database management system in Incheon to establish birth defects monitoring system to evaluate the incidence rate and patterns of birth defects in Korea. Public health center and private hospitals and clinics participated in this monitoring system. Web based reporting system have been built and operated during 2 years (first year: December 1st, 1998-November. 31, 1999; second year: January 1st, 2000 - December 31th, 2000). Trained nurses actively collected the records obtained from delivery units in the participating hospitals. During first and second year, the incidence rate of birth defect per thousand person was 10.0 and 8.0 respectively. In conclusion, we could build web-based monitoring system for birth defects successfully in Yonsu gu, Incheon. It could be a model of national standard for population-based monitoring system for birth defects in Korea.

Expression and characterization of the flavoprotein domain of gp91phox

Truncated forms of gp91(phox) were expressed in E. coli in which the N-terminal hydrophobic transmembrane region was replaced with a portion of the highly soluble bacterial protein thioredoxin (TRX). TRX-gp91(phox) (306-569), which contains the putative FAD and NADPH binding sites, showed NADPH-dependent NBT (nitroblue tetrazolium) reductase activity, whereas TRX-gp91(phox) (304-423) and TRX-gp91(phox) (424-569) were inactive. Activity saturated at about a 1:1 molar ratio of FAD to TRX-gp91(phox) (306- 569), and showed the same Km for NADPH as that for superoxide generating activity by the intact enzyme. Activity was not inhibited by superoxide dismutase, indicating that it was not mediated by superoxide, but was blocked by an inhibitor of the respiratory burst oxidase, diphenylene iodonium (DPI). In the presence of Rac1, the cytosolic regulatory protein p67(phox) stimulated the NBT reductase activity, but p47(phox) had no effect. Truncated p67(phox) containing the activation domain (residues 199- 210) stimulated activity approximately 2-fold, whereas forms mutated or lacking this region failed to stimulate the activity. Our data indicate that: 1) TRX-gp91(phox) (306-569) contains the binding sites for both pyridine and flavin nucleotides; 2) this flavoprotein domain shows NBT reductase activity; and 3) the flavin-binding domain of gp91(phox) is the target of regulation by the activation domain of p67(phox).

Activation domain in P67phox regulates the steady state reduction of FAD in gp91phox

An activation domain in p67(phox) (residues 199-210) is critical for regulating NADPH oxidase activity in cell-free system [10] To determine the steady state reduction of FAD, thioacetamide-FAD was reconstituted in gp91(phox), and the fluorescence of its oxidised form was monitored. Omission of p67(phox) decreased the steady state reduction of the FAD from 28% to 4%, but omission of p47(phox) had little effect. A series of the truncated forms of p67(phox) were expressed in E.coli to determine the domain in p67(phox) which is essential for regulating the steady state of FAD reduction. The minimal length of p67(phox) for for regulating the steady state of FAD reduction is shown to be 1-210 using a series of truncation mutants which indicates that the region 199-210 is also important for regulating electron flow within flavocytochrome b(558). The deletion of this domain not only decreased the superoxide generation but also decreased the steady state of FAD reduction. Therefore, the activation domain on p67(phox) regulates the reductive half-reaction for FAD, consistent with a dominant effect on hydride/electron transfer from NADPH to FAD.

The Change of Platelet Count and Plasma Fibrinogen Level during and after Extracorporeal Circulation / 대한마취과학회지

In order to evaluate causes and the effective treatment of postoperative bleeding after open heart surgery, we measured platelet count and plasma fibrinogen levels before, during a 30 and 60-minute, and after a 30, 60 and 90-minute extracorporeal circulation in 5 patients perfused by a bubble and membrane oxygenator, respectively. The results were as follows: 1) The platelet count was reduced significantly by 57.2+/-3.04% during a 30-minute extracorporeal circulation using the bubble oxygenator and by 43.8+/-0.84% using the membrane oxygenator, and these levels were maintained throughout the extracorporeal circulation. 2) The platelet count after a 90-minute extracorporeal circulation increased significantly compared with after a 30-minute extracorporeal circulation (p<0.05) and these effects were more prominent using the bubble oxygenator (p<0.025). 3) The plasma fibrinogen level was reduced by 28.6+/-7.50% during a 30-minute extracorporeal circulation using the bubble oxygenator and by 33.6+/-5.77% using the membrane oxygenator, and these levels were maintained throughout the extracorporeal circulation. 4) The plasma fibrinogen level after a 90-minute extracorporeal circulation increased significantly compared with after a 30-minute extracorporeal circulation (p<0.05).