The Effect of Fluid Shear Stress on Endothelial Cell Adhesiveness to Polymer Surfaces with Wettability Gradient

In this study, the adhesive strength of endothelial cells (ECs) attached on polymer surfaces with different hydrophilicity was investigated using wettability gradient polyethylene (PE) surfaces prepared by corona discharge treatment from a knife-type electrode whose power increases gradually along the sample length. The EC-attached wettability gradient surfaces were mounted on parallel-plate flow chambers in a flow system prepared for cell adhesiveness test. Three different shear stresses (150, 200, and 250 dyne/cm(2)) were applied to the flow chambers and each shear stress was maintained for 120 min to investigate the effect of shear stress and surface hydrophilicity on the EC adhesion strength. It was observed that the ECs were adhered more onto the positions with moderate hydrophilicity of the wettability gradient surface than onto the more hydrophobic or hydrophilic positions. The maximum adhesion of the cells appeared at around water contact angles of 55 degrees. The EC adhesion strength was higher on the hydrophilic positions than on the hydrophobic ones. However, the maximum adhesion strength of the cells also appeared at around water contact angles of 55 degrees. More than 90% of the adhered cells remained on that position after applying the shear stress, 250 dyne/cm(2) for 2 h, whereas the cells were completely detached on the hydrophobic position (water contact angle, about 86 degrees ) within 10 min after applying the same shear stress. It seems that surface hydrophilicity plays a very important role for cell adhesion strength. Copyright 2000 Academic Press.

Selective involvement of reactive oxygen intermediates in platelet-activating factor-mediated activation of NF-kappaB

Although it has been suggested that some biological activities of platelet-activating factor (PAF) are mediated by, at least in part, reactive oxygen intermediates (ROI), the precise mechanisms underlying the interaction between the two remains to be elucidated. Antioxidants, such as alpha-tocopherol acid succinate, N-acetyl-L-Cysteine, pyrrolidinedithiocarbamate failed to inhibit PAF-induced immediate systemic reactions such as lethality, symptoms of disseminated intravascular coagulation, and histological changes such as pulmonary edema and hemorrhage in renal medullae 10 min following PAF injection. In contrast. antioxidants significantly inhibited both the in vivo and in vitro PAF-induced NF-kappaB activation and NF-kappaB-dependent TNF-alpha expression. The effects of the antioxidants were due to their inhibition of PAF-induced degradation of IkappaBalpha, a protein responsible for keeping NF-kappaB in an inactive form. A protein tyrosine kinase and N-tosyl-L-phenylalanine chloromethyl ketone sensitive serine protease were involved in both PAF- and H2O2-induced NF-kappaB activation. Collectively, these data indicate that the PAF-induced NF-kappaB activation is selectively mediated through the generation of ROI.

Gene polymorphisms of endothelial nitric oxide synthase and angiotensin-converting enzyme in patients with asthma

BACKGROUND

Nitric oxide, including that produced by endothelial constitutive nitric oxide synthase (ecNOS), may regulate vascular and airway tone in the lungs and may influence various aspects of airway homeostasis. Angiotensin-converting enzyme (ACE) is expressed at high levels in the lungs and plays a role in the metabolism of angiotensin II, bradykinin, and substance P, all of which are potentially involved in the pathogenesis of asthma. An insertion-deletion polymorphism of the ACE gene has been shown to be associated with enzyme activity levels of ACE. To examine the possible involvement of the ecNOS and/or ACE genes as the genetic basis of bronchial asthma, we investigated whether there was any association between bronchial asthma and polymorphisms of the ecNOS and/or ACE genes.

METHODS

A total of 310 patients with bronchial asthma and 121 healthy subjects took part in this study. The ecNOS and ACE genotypes were determined in all subjects by polymerase chain reaction.

RESULTS

1) The distribution of one genotype (bb) of ecNOS was significantly higher in the asthma group than in the control population. 2) The ACE genotype distribution was not significantly different between the control and the asthma groups. 3) In asthmatic patients, the ACE and ecNOS genotype distribution did not differ significantly among groups of patients with different severities of asthma.

CONCLUSIONS

These results suggest that polymorphisms of the ecNOS gene, but not the ACE gene, may be associated with the development of asthma. However, the severity of asthma may not be influenced by polymorphisms of the ecNOS and ACE genes.

Peritoneal transport characteristics, comorbid diseases and survival in CAPD patients

OBJECTIVE

To evaluate the influence of initial peritoneal transport rate, serum albumin concentration, and comorbid diseases on continuous ambulatory peritoneal dialysis (CAPD) patient survival.

DESIGN

A prospective single-center study with a long-term follow-up.

PATIENTS

A total of 213 consecutive CAPD patients, who underwent a peritoneal equilibration test (PET) at a mean of 7 days (range 3 - 30 days) after beginning CAPD, were included in this study. One hundred twenty patients were male, 116 patients had comorbid diseases, and mean age was 49.5 years (range 18 - 76 years).

METHODS

A modified PET was performed using 4.25% glucose dialysis solution. Based on the dialysate-to-plasma creatinine concentration ratio at 4 hours' dwell (D4/P4 Cr, 0.62 +/- 0.14), patients were divided into high (H), high-average (HA), low-average (LA), or low (L) transporters.

RESULTS

Of 213 patients, 16.9% were classified as H transporters, 30.5% as HA, 36.6% as LA, and 16.0% as L transporters. The H transporter group had a higher proportion of men, higher proportion of patients with comorbid diseases, lower initial serum albumin concentration, lower D4/D0 glucose, and lower drained volume. The initial D4/P4 Cr correlated with initial serum albumin (r= -0.35, p < 0.001). The patients with comorbid diseases had lower initial serum albumin and higher initial D4/P4 Cr. On Kaplan-Meier analysis, 2-year patient survival of group H was significantly lower compared to the other groups combined (57.1% vs 79.5%, p = 0.009). On Cox proportional hazards analysis, age, comorbid diseases, initial serum albumin concentration, and initial D4/P4 Cr were found to be independent risk factors for mortality. However, in the patients without comorbid diseases, patient survival was not different between group H and the other transport groups combined (p > 0.05), and only age was found to be an independent risk factor for mortality.

CONCLUSION

These data suggest that a high peritoneal transport rate at initial PET is associated with high mortality, and that this is in part due to an increased prevalence of comorbid disease in H transporters. These H transporters with comorbid diseases represent a subset of patients with an especially poor prognosis. In patients without comorbid diseases, high transport status or low serum albumin concentration was not an independent risk factor for mortality.

Effect of lovastatin on small GTP binding proteins and on TGF-beta1 and fibronectin expression

We have shown that lovastatin, an inhibitor of 3 hydroxy-3-methylglutary coenzyme A (HMG CoA) reductase, delays development and progression of diabetic nephropathy in streptozotocine-induced diabetic rats through suppression of glomerular transforming growth factor (TGF)-beta1 mRNA expression. We have also shown that lovastatin suppresses both control and high glucose (HG)-induced TGF-beta1 and fibronectin mRNA expression and protein synthesis by rat mesangial cell (RMC) and that this down-regulation by lovastatin is reversed by mevalonate. It was postulated that this down-regulation may be linked to signaling of small guanine triphosphate (GTP)-binding proteins and mediated by the limitation of isoprenoids such as farnesylpyrophosphate (FPP) and geranylgeranylpyrophosphate (GGPP) in RMC. To determine the isoprenoid and small GTP-binding proteins involved in TGF-beta1 and fibronectin expression. FPP or GGPP was added alone or in combination to RMC treated with lovastatin cultured under normal or high glucose condition. Suppression of TGF-beta1 and fibronectin expression by lovastatin was reversed effectively when GGPP was added alone. Partial reversal of lovastatin effect on fibronectin and TGF-beta1 expression was found when FPP was added alone. Adding both GGPP and FPP resulted in complete reversal of lovastatin effect on fibronectin but not TGF-beta1 suggesting that fibronectin and TGF-beta1 are regulated differently. Furthermore, luciferase activity of RMC cotransfected with fibronectin promoter reporter system and plasmid-expressing C3 exoenzyme (a specific inactivator of Rho family GTP binding proteins, pEFC3) was completely suppressed when compared with RMC cotransfected with empty vector, pEF. Because geranylgeranylation is usually involved in post-translational modification and membrane targeting of Rho family small GTP binding proteins, these data indicate that Rho family small GTP-binding proteins rather than Ras family small GTP binding proteins may play a key role in the TGF-beta1 and fibronectin expression in RMC.

Reactive oxygen species as glucose signaling molecules in mesangial cells cultured under high glucose

BACKGROUND

Oxidative stress is one of the important mediators of vascular complications in diabetes including nephropathy. High glucose (HG) generates reactive oxygen species (ROS) as a result of glucose auto-oxidation, metabolism, and formation of advanced glycosylation end products. The concept of ROS-induced tissue injury has recently been revised with the appreciation of new roles for ROS in signaling pathways and gene expression.

METHODS AND RESULTS

High glucose rapidly generated dichlorofluorescein-sensitive cytosolic ROS in rat and mouse mesangial cells. Neither L-glucose nor 3-O-methyl-D-glucose increased cytosolic ROS and cytochalasin B, an inhibitor of glucose transporter, effectively inhibited HG-induced ROS generation, suggesting that glucose uptake and subsequent metabolism are required in HG-induced cytosolic ROS generation. H2O2 up-regulated fibronectin mRNA expression and protein synthesis; this up-regulation was effectively inhibited by protein kinase C (PKC) inhibitor or by depletion of PKC. The HG-induced generation of ROS was, in turn, related to activation of PKC and transcription factors nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) as well as to the up-regulation of transforming growth factor-beta1 (TGF-beta1), fibronectin mRNA expression and protein synthesis, because antioxidants effectively inhibited HG-induced PKC, NF-kappaB, AP-1 activation, and TGF-beta1 and fibronectin expression in mesangial cells cultured under HG.

CONCLUSIONS

Although signal transduction pathways linking HG, ROS, PKC, transcription factors, and extracellular matrix (ECM) protein synthesis in mesangial cells have not been fully elucidated, the current data provide evidence that ROS generated by glucose metabolism may act as integral signaling molecules under HG as in other membrane receptor signaling.

Phellinsin A, a novel chitin synthases inhibitor produced by Phellinus sp. PL3

Phellinsin A, a novel chitin synthases inhibitor was isolated from the cultured broth of fungus PL3, which was identified as Phellinus sp. PL3. Phellinsin A was purified by solvent partition, silica gel, ODS column chromatographies, and preparative HPLC, consecutively. The structure of phellinsin A was assigned as a phenolic compound on the basis of various spectroscopic analyses including UV, IR, Mass, and NMR. Its molecular weight and formula were found to be 358 and C18H14O8, respectively. Phellinsin A selectively inhibited chitin synthase I and II of Saccharomyces cerevisiae with an IC50 value of 76 and 28 microg/ml, respectively, in our cell free assay system. This compound showed antifungal activity against Colletotrichum lagenarium, Pyricularia oryzae, Rhizoctonia solani, Aspergillus fumigatus, and Trichophyton mentagrophytes.

Nifedipine controlled delivery by sandwiched osmotic tablet system

The sandwiched osmotic tablet system (SOTS), which is composed of a sandwiched osmotic tablet core surrounded by a cellulose acetate membrane with two orifices on both side surfaces, has been successfully prepared with the purpose of delivering nifedipine. The sandwiched osmotic tablet core consists of a middle push layer and two attached drug layers. Influences of tablet formulation variables, orifice size and membrane variables on nifedipine release of SOTS have been studied. It was found that potassium chloride amount of push layer and polyethylene oxide amount of drug layer had markedly positive effects on nifedipine release. A push layer/drug layer co-controlled osmotic delivery mechanism and the optimal core formulation have been proposed. The appropriate orifice size was observed in the range of 0.50-1.41 mm. It was also found that the drug release rate of SOTS could be increased by incorporating hydrophilic plasticizer in the membrane, whereas it decreased with hydrophobic plasticizer. It has been observed that the SOTS gives fairly comparable in vitro release features as that of commercialized push-pull osmotic tablet system, such as an approximately constant rate up to 24 h and independence of release media and agitation rate. Exempting side identification before drilling, it is easier to prepare the SOTS than the push-pull osmotic tablet system.

Effect of combined therapy of oral anti-tubercular agents on theophylline pharmacokinetics

To evaluate the effects of combined therapy of anti-tubercular agents with theophylline during treatment of concurrent pulmonary tuberculosis and chronic obstructive pulmonary disease or asthma, the clearance and half life of theophylline was estimated in a control group not treated with anti-tubercular agents, a group treated with isoniazid (INH), rifampicin (RMP), ethambutol (EMB) and pyrazinamide (PZA), and a group treated with INH, RMP and EMB. Clearances of theophylline in the treated groups were significantly lower than in the control group, and the half-life of theophylline was longer than in the control. These results suggest that patients administered combinations of anti-tubercular agents with theophylline require lower doses of theophylline.

Monolithic osmotic tablet system for nifedipine delivery

The monolithic osmotic tablet system, which is composed of a monolithic tablet coated with cellulose acetate (CA) membrane drilled with two orifices on both side surfaces, has been described. The influences of tablet formulation variables including molecular weight (MW) and amount of polyethylene oxide (PEO), amount of potassium chloride (KCl), and amount of rice starch as well as nifedipine loading have been investigated. The optimal tablet formulation and the osmotic-suspending co-controlled delivery mechanisms have been proposed. Orifice size and membrane variables including nature and amount of plasticizers as well as thickness on drug release have also been studied. The in vitro release profiles of the optimal system have been evaluated in various release media and different agitation rates, and compared with commercialized conventional capsule and push-pull osmotic tablet. It was found that PEO with MW of 300000 g/mol was suitable to be thickening agent, both amount of KCl and amount of PEO had comparable and profoundly positive effects, while nifedipine loading had a strikingly negative influence on drug release. It could be found that the optimal orifice size was in the range of 0.25-1.41 mm. It has also been observed that hydrophilic plasticizer polyethylene glycol (PEG) improved drug release, whereas hydrophobic plasticizer triacetin depressed drug release when they were incorporated in CA membrane. The monolithic osmotic tablet system was found to be able to deliver nifedipine at the rate of approximate zero-order up to 24 h, independent of both environmental media and agitation rate, and substantially comparable with the push-pull osmotic tablet. The monolithic osmotic tablet system was simple to be prepared as exempting from push layer and simplifying in the orifice drilling compared with the push-pull osmotic tablet. The monolithic osmotic tablet system may be used in drug controlled delivery field, especially suitable for water-insoluble drugs.

Grass carp (Ctenopharyngodon idellus) bile may inhibit the release of renal dipeptidase from the proximal tubules by nitric oxide generation

There are many reports on acute renal failure (ARF) after ingestion of grass carp bile (CB; Ctenopharyngodon idellus). Renal dipeptidase (RDPase; EC 3.4.13.19) is a glycosylphosphatidylinositol-anchored ectoenzyme within the renal proximal tubules (PTs) and is proposed as a diagnostic enzyme of renal disease. We examined the release of RDPase following treatment with CB and various nitric oxide (NO) related compounds in porcine PTs. The RDPase release from PTs was inhibited by CB in a concentration-dependent manner and was also inhibited by sodium nitroprusside (direct NO donor) and L-arginine (NO synthase substrate) in the tested range (0-12 mM). CB-treated (0. 1 mg/ml) PTs showed a decreased RDPase activity in comparison with the control group. This inhibition was blocked by 2 mM L-NAME (NO synthase inhibitor) and U73122 (inhibitor of phosphatidylinositol-specific phospholipase C) in a concentration-dependent manner. Eel bile (0-0.1 mg/ml), used as the control, did not significantly affect the RDPase release from PTs. The NO concentration was observed as nitrite, the degradation product of the NO metabolism, increased in proportion to CB and L-arginine. The increase of nitrite to 151.5% by CB treatment (0.1 mg/ml) was blocked by 2 mM L-NAME (95.5%). When the phospholipase C pathway was blocked by 10 and 20 microM U73122, the nitrite generation decreased to 122.7 and 89.4%, respectively. These results strongly suggest that NO generation and the phospholipase C pathway affect the RDPase release from the PTs and that they may be involved in the development of ARF in vivo following CB ingestion. The release of RDPase from PTs could be a useful tool not only for this CB-caused ARF, but also for the elucidation of other biochemical mechanisms.

Sandwiched osmotic tablet core for nifedipine controlled delivery

The sandwiched osmotic tablet core, which is composed of a middle push layer and two attached drug layers, has been prepared and systematically studied with the purpose of delivering water-insoluble nifedipine. The advantage of the sandwiched osmotic tablet system over the commercialized push-pull osmotic tablet system is its simplicity of preparation, as the surface identification was avoided. It was observed that polyethylene oxides (PEO) with molecular weight (MW) of 300,000 and 8,000,000 g/mole were suitable for the thickening agent of drug layer and the expandable hydrogel of push layer, respectively. The weight ratio of 190/190 for drug layer/push layer was also found to be suitable. It has been observed that PEO amount of the push layer and the KCl amount of the drug layer had profoundly positive influence on nifedipine release. A push layer/drug layer co-controlled osmotic delivery mechanism has been proposed and the optimal tablet formulation has been obtained. It was also found that PEO and nifedipine were miscible, which may support the application of PEO in nifedipine dosage forms. Meanwhile, the PEO/nifedipine binary phase diagram has been constructed. The sandwiched osmotic tablet system can deliver nifedipine in an approximate zero-order rate up to 24 hours. It may be potentially used for the delivery of water-insoluble drugs.

Gap measurement by position-sensitive detectors

A system for measuring the gap in a proximity exposure tool of a plasma display panel (PDP) is developed that uses single or dual position-sensitive detectors (PSD's). The resolution of the gap distance is 0.5 mum, with a capture range of 500 mum. Signal processing is simple and fast and easy because analogous PSD's are used as the position sensors. One PSD is used to detect the position of the reference beam, which is reflected from the upper surface of the gap; the other PSD is used to detect the position of the signal beam, which is reflected from the lower surface of the gap. A charge-coupled-device sensor is also employed to monitor the reflected beams and the region of measurement. In the gap-measurement system that uses a single PSD, first the reference beam is incident upon the PSD and then the signal beam is incident upon the same PSD. Then the separation between the two beams is calculated from the position of the reference beam and from the average beam position.

Environment factors influence in vitro interspecific interactions between A. ochraceus and other maize spoilage fungi, growth and ochratoxin production

The effect of water availability (water activity, aw; 0.995-0.90) and temperature (18-30 degrees C) on in vitro interactions between an ochratoxin producing strain of Aspergillus ochraceus and six other spoilage fungi was assessed in dual culture experiments on a maize meal-based agar medium. In primary resource capture of nutrient substrate, A. ochraceus was dominant against many of the interacting species, being able to overgrow and replace A. candidus, and sometimes A. flavus and the Eurotium spp. regardless of aw or temperature. However, with freely available water (0.995 aw) A. alternata and A. niger were dominant, with mutual antagonism between A. ochraceus and A. flavus at 25-30 degrees C. In the driest conditions tested (0.90 aw) there was also mutual antagonism between A. ochraceus and the two Eurotium spp. Overall, under all conditions tested the Index of Dominance for A. ochraceus was much higher than for other competing species combined suggesting that A. ochraceus was a good competitive colonist able to replace a number of other species. However, the growth rate of A. ochraceus was modified and decreased by the interaction with competitors. Interaction between A. ochraceus and species such as A. alternata (18 degrees C/0.995) and Eurotium spp. (0.995-0.95 and 25-30 degrees C) resulted in a significant stimulation of ochratoxin production. The results are discussed in relation to the effect that environmental factors have on the possible competitiveness of A. ochraceus in the maize grain ecosystem and the role of ochratoxin in niche exclusion of competitors.

Chaetoatrosin A, a novel chitin synthase II inhibitor produced by Chaetomium atrobrunneum F449

Chaetoatrosin A, a novel chitin synthase II inhibitor, was isolated from the culture broth of fungus F449, which was identified as Chaetomium atrobrunneum F449. Chaetoatrosin A was purified by solvent partition, silica gel, ODS, preparative TLC, and Sephadex LH-20 column chromatographies, consecutively. The structure of chaetoatrosin A was assigned as 1,8-dihydroxy-3(2-hydroxypropionyl)-6-methoxynaphthalene on the basis of various spectroscopic analyses including UV, IR, mass spectral, and NMR. Its molecular weight and formula were found to be 262 and C14H14O5, respectively. ,Chaetoatrosin A inhibited chitin synthase II by 50% at the concentration of 104 microg/ml in an enzyme assay system. This compound showed antifungal activities against Rhizoctonia solani, Pyricularia oryzae, Botrytis cinerea, Cryptococcus neoformans and Trichophyton mentagrophytes.

ECP level in nasopharyngeal secretions and serum from children with respiratory virus infections and asthmatic children

Infection with respiratory virus has been shown to exacerbate asthma in humans. However, the role of a respiratory virus in the pathogenesis of chronic asthma and/or wheezing in young children has not been clearly defined. It has also been debated whether virus-induced wheezing in young children is one entity and allergic asthma another, or whether they are different expressions of the same disease. The present study was done to compare ECP concentrations in nasopharyngeal secretions and serum from 32 nonasthmatic wheezing children with viral infections (RSV in 15 children; influenza B virus in 17 children detected by immunofluorescence antibody technique), 8 asthmatic children without viral infections, and 13 normal children as the controls to understand the role of eosinophil inflammation. The geometric mean of ECP in nasopharyngeal secretions was significantly higher in asthmatic children than in children with virus-induced wheezing (p < 0.05). ECP levels of nasopharyngeal secretions from children with the virus-induced wheezing were significantly greater than those of the controls. However, there were no significant differences in ECP levels in serum among subjects.

Determination of bisphenol A in sewage effluent and sludge by solid-phase and supercritical fluid extraction and gas chromatography/mass spectrometry

Methods have been developed for the determination of bisphenol A (BPA) residues in municipal sewage and sludge samples. BPA in wastewater samples was enriched with a C18 solid-phase extraction cartridge, eluted with acetone, and converted to the pentafluoropropionyl derivative. For sludge samples, BPA was acetylated and extracted with supercritical carbon dioxide. In both cases, BPA-d16 was used as a surrogate to monitor extraction efficiency. Final analyses of derivatized sample extracts were performed by gas chromatography/mass spectrometry operating in the electron impact mode. For water samples, mean recoveries and standard deviations were 89 +/- 6, 94 +/- 4, and 85 +/- 7% at fortification levels of 1, 0.1, and 0.025 microg/L, respectively, with a method detection limit of 0.006 microg/L. For solid waste samples, mean recoveries and standard deviations were 93 +/- 5 and 92 +/- 6% at fortification levels of 2.5 and 0.25 microg/g, respectively, and the method detection limit was 0.05 microg/g. For the Canadian samples under investigation, concentrations of BPA ranged from 49.9 to 0.031 microg/L in sewage influent and effluent, and from 36.7 to 0.104 microg/g in sludge.

Influence of initial nutritional status on continuous ambulatory peritoneal dialysis patient survival

OBJECTIVES

To evaluate the influence of initial nutritional status on continuous ambulatory peritoneal dialysis (CAPD) patient survival and to identify factors determining initial nutritional status and patient mortality.

DESIGN

Prospective single-center study.

SETTING

Kidney Center, Soon Chun Hyang University Hospital.

PATIENTS

A total of 91 consecutive CAPD patients, who underwent initial nutritional assessment at Soon Chun Hyang University Hospital, Seoul, Korea, between September 1994 and January 1999, was included in this study. All patients were assessed at a mean of 7 days after beginning CAPD (range 3 - 24 days). Forty-eight patients were male, 50 were diabetics, and their mean age was 53.9 years (range 22 - 76 years).

METHODS

Nutritional status was assessed by subjective global assessment (SGA), biochemical and anthropometric measurements, fat-free edema-free (FFEF) body mass by creatinine kinetics, urea kinetic studies, and calculation of the normalized protein equivalent of total nitrogen appearance (nPNA).

RESULTS

By SGA, 55% were classified as having normal nutrition while 45% had signs of malnutrition; 61% of female and 31% of male patients, and 54% of diabetics and 34% of nondiabetics were classified as malnourished. Initial FFEF body mass, blood urea nitrogen (BUN), serum albumin (sAIb), residual renal function (RRF), and weekly total creatinine clearance were significantly lower in the malnourished patients than in the patients with normal nutrition. On multiple regression analysis, only FFEF body mass was an independent determinant of SGA score. On 31 January 1999, 41 patients were still on CAPD, 15 patients had died, and 27 patients had been transferred to hemodialysis. Those who died during observation were older and had lower initial FFEF body mass, % lean body mass, BUN, sAIb, RRF, and SGA score. The 2-year patient survival rate was significantly lower in the malnourished than in normal patients (67.1 % vs 91.7%, p = 0.02). On Cox proportional hazards analysis, initial age, malnutrition assessed by SGA, and FFEF body mass were identified as factors determining death.

CONCLUSION

Malnutrition was present in 45% of patients commencing CAPD when assessed by SGA. Initial FFEF body mass was a determinant of SGA score and predicted death. Malnutrition as assessed by SGA was also an independent predictor of death. Initial nutritional status, therefore, appears to exert a powerful influence on CAPD patient survival.

Interaction of fibroblast cells on poly(lactide-co-glycolide) surface with wettability chemogradient

Chemogradient surfaces whose properties are changed gradually along the sample length are of particular interest for the basic studies of the interaction between biological species and surfaces since the effect of a selected property can be examined in a single experiment on one surface. A wettability chemogradient on the poly(L-lactide-co-glycolide) (PLGA) films by treating them in air with corona from a knife-type electrode whose power increases gradually along the sample length. The PLGA surfaces oxidized gradually with the increasing corona power, and the wettability chemogradient was created on the surfaces as evidenced by the measurement of water contact angles and electron spectroscopy for chemical analysis. The wettability chemogradient PLGA surfaces prepared were used to investigate the interaction of fibroblast cells in terms of the surface hydrophilicity/hydrophobicity of PLGA surface. The cells adhered and grown on the chemogradient surface along the sample length were counted and observed by scanning electron microscopy. It was observed that the cells were adhered, spread, and grown more onto positions with moderate hydrophilicity of the wettability chemogradient PLGA surface than onto the more hydrophobic or hydrophilic positions. The maximum adhesion and growth of the fibroblast cells appeared at around water contact angle of 55 degrees. It seems that the wettability plays important roles for cell adhesion, orientation, spreading and growth on the PLGA surface. It might be that this surface modification technique can be used for improving the adhesion and growth of cell onto PLGA film and scaffolds, and can be applicable in the area of the tissue engineering.

The effect of the chemical structure of the phospholipid polymer on fibronectin adsorption and fibroblast adhesion on the gradient phospholipid surface

The interaction between biocomponents and the polyethylene (PE) surface modified with poly[omega-methacryloyloxyalkyl phosphorylcholine (MAPC)] was considered taking into account the surface characteristics, i.e., density, mobility, and orientation of the poly(MAPC). The PE surface, grafted gradually with the poly(MAPC) was prepared by corona irradiation method. The amount of peroxide produced on the PE surface which was determined with 1,1-diphenyl-2-picryl-hydrazyl, increased with an increase in the energy of the corona. The surface density of the poly(MAPC) was increased with an increase in the amount of the peroxides produced by the corona irradiation. The orientation and mobility of the poly(MAPC) grafted on the PE surface was evaluated with 1,6-diphenyl-1,3,5-hexatriene. The orientation of the poly[6-methacryloyloxyhexyl phosphorylcholine (MHPC)] which has six methylene chains between the phospholipid polar group and the backbone was higher than that of other poly(MAPC)s. The mobility of the poly(MAPC) decreased with an increase in the methylene chain length in the MAPC unit. The fibronectin adsorption on the gradient PE sheet grafted with poly(MAPC) was determined with enzyme-labeled immunoassay. The amount of adsorbed fibronectin on the PE grafted with poly[2-methacryloyloxyethyl phospohorylcholine(MPC)] and poly(MHPC) decreased with an increase in their surface density. Especially, the PE sheet grafted with the poly(MHPC) was effectively reduced compared with other poly(MAPC)s. On the poly[10-methacryloyloxydecyl phosphorylcholine (MDPC)], there is a minimum amount of adsorbed fibronectin. The fibronectin adsorption pattern on the PE sheet grafted with poly(MAPC) was quite different from the chemical structure of the MAPC unit. The human normal diploid fibroblasts (WI-38 cells) were cultured on the gradient PE sheet grafted with poly(MAPC) changing the concentration of seeded WI-38 cells. The adhesion behavior of the WI-38 cells was different depending on the concentration of the seeded WI-38 cells. When the concentration was low, the number of the adherent WI-38 cells had the same tendency as fibronectin adsorption. The gradient PE sheet grafted with the poly(MHPC) effectively reduced WI-38 cells adhesion even when the concentration of the WI-38 cells was high. The biocompatibility of polymer surfaces can be improved by highly oriented phosphorylcholine group.

Orbital floor and infraorbital rim reconstruction after total maxillectomy using a vascularized calvarial bone flap

A number of techniques have been introduced to support the orbital floor after maxillectomy without orbital exenteration. These methods include skin graft or muscular sling, but they have resulted in severe complications, such as enophthalmos, global ptosis, diplopia, and facial deformity. Currently, advanced microvascular reconstruction using bone and soft tissue is performed by many surgeons. This usually results in the filling of the postmaxillectomy defect, but the lack of support for the orbital rim and floor by the bone flap may still cause the complications mentioned above. Vascularized calvarial bone flap was chosen in this study for reconstruction of the orbital floor and infraorbital rim to function as a buttress, to reconstruct recipient sites of poor vascular bed after radiation therapy, and to withstand further postoperative radiation. By providing a solid floor and rim, these complications can be prevented with satisfactory function and aesthetically acceptable results. From September of 1995 to July of 1998, we performed vascularized bone flap for the reconstruction of the orbital floor and infraorbital rim in four cases after total maxillectomy involving the orbital floor. With a follow-up period from 19 to 35 months (mean, 27 months), we obtained significant improvement of functional and aesthetically acceptable results without global ptosis, enophthalmos, diplopia, or severe facial contour deformity.

Peritoneal transport of glucose in rat

OBJECTIVE

To evaluate the convective transport characteristics of glucose and the effect of high glucose and insulin during experimental peritoneal dialysis in rat.

METHODS

Male Sprague-Dawley rats weighing 300-400 g were used in this study. Mannitol (5%) was used as osmotic agent. Glucose was added to dialysis solution to yield a concentration of 100 mg/dL (group 1) or 300 mg/dL (group 2). Mannitol solution (5%) containing the same concentration of electrolytes and lactate but without glucose was used as control (group 3). In group 2, blood sugar was maintained at approximately 300 mg/dL by continuous intravenous infusion of 25% glucose solution and 0.9% NaCl solution. A 2-hour dwell study was performed with 30 mL of test solutions. Intraperitoneal volume was calculated by volume marker (18.5 kBq of 131I-human radioiodinated serum albumin, RISA) dilution with corrections made for the elimination of RISA from the peritoneal cavity (K(E)) and sample volume. The diffusive mass transport coefficient (K(BD)) and sieving coefficient (S(BRF)) were calculated by using the Babb-Randerson-Farrell model. S was also calculated directly by using isocratic methods (S(I)). The peritoneal fluid absorption rate (K(E)) was taken into account for the calculation of S(I).

RESULTS

Intraperitoneal volume was significantly higher in group 2 compared with groups 1 and 3. Peritoneal fluid absorption rate, K(E), was similar in all three groups. S(BRF) and S(I) for glucose were significantly lower in group 2 compared with groups 1 and 3. S(BRF) for glucose in group 2 was below zero and S(I) near zero. K(BD) for glucose was significantly higher in group 2 than in groups 1 and 3. Plasma and dialysate concentrations of insulin increased during the initial hour and then decreased to the baseline value in groups 1 and 3, while in group 2 it continuously increased.

CONCLUSION

Significantly lower sieving coefficients for glucose in the high glucose and high insulin group suggest that transport mechanisms other than simple passive transport are involved in peritoneal glucose transport, and that high glucose per se and/or high insulin may be important factors that determine glucose transport characteristics.