Correlation between periodontal status and biting ability in Chinese adult population

This study investigated the relation between periodontal condition and biting ability in a Chinese population using the pressure-detecting sheet. A total of 142 subjects residing in Nanchang, Jiangxi province, China, participated in the study. The examination included probing pocket depth (PD), clinical attachment level (CAL), bleeding on probing and coronal caries teeth. Biting abilities per person, biting force, biting pressure and occlusal contact area were measured using the sheet. Number of teeth present showed positive correlation with biting force and occlusal contact area, but were negatively correlated with biting pressure. No significant correlation was observed between the mean PD, percentage of pocket > or = 4 mm, bleeding index and any of biting abilities. The mean CAL showed a significantly negative correlation with biting force and occlusal contact area. Multiple stepwise regression analysis selected the number of teeth present, sex and age as the significant factors affecting the biting ability. However, no periodontal indices were picked up as the significantly contributing factor. There appears to be little effect of periodontal condition on biting ability. Ageing was selected as a contributing factor to reduction in the Chinese adults, but not in the Japanese population.

The role of tissue macrophages in the induction of proinflammatory cytokine production following intravenous injection of lipoplexes

Recent studies have demonstrated that intravenous administration of a plasmid DNA-cationic liposome complex (lipoplex) induced significant proinflammatory cytokine production in blood and inhibited transgene expression in pulmonary endothelial cells. In this study, we examined the effects of gadolinium chloride (GdCl(3)) pretreatment on the biodistribution and induction of proinflammatory cytokine production and transgene expression after intravenous injection of a lipoplex in mice. GdCl(3) is known to transiently deplete liver Kupffer cells and spleen macrophages after intravenous administration. Intravenous administration of a lipoplex triggers high levels of proinflammatory cytokine production, such as TNF-alpha, IFN-gamma and IL-12 in serum and a large amount of (32)P-labeled lipoplex accumulates in the liver 1 h after intravenous administration. However, pretreatment with GdCl(3) dramatically reduces serum levels of these cytokines and liver accumulation of the lipoplex. RT-PCR analysis showed that mRNA expression of TNF-alpha greatly increases in the liver and spleen after lipoplex injection and that pretreatment with GdCl(3) reduces mRNA expression in these organs. Messenger RNA expression of TNF-alpha in the liver occurs in non-parenchymal cells (sinusoidal endothelial cells and/or Kupffer cells). Inhibition of cytokine production by pretreatment with GdCl(3) leads to recovery of transgene expression in the lung following the second injection of lipoplex, which was reduced following the first injection of lipoplex. Thus, the present study demonstrates that tissue macrophages involving liver Kupffer cells and spleen macrophages are closely involved in TNF-alpha production following i.v. administration of the lipoplex. It is also suggested that avoiding lipoplex uptake and subsequent cytokine production by these cells would be a useful method of maintaining a high level of gene expression in the lung after repeated injections.

Pharmacokinetic analysis of lectin-dependent biodistribution of fucosylated bovine serum albumin: a possible carrier for Kupffer cells

To examine the potential utility of fucosylation of drug carriers for targeted drug delivery to Kupffer cells, the pharmacokinetics of (111)In-labeled fucosylated bovine serum albumin (Fuc-BSA) with different numbers of fucose residues (11, 16, 25, 31 or 41) was studied. After intravenous injection in mice, all (111)In-Fuc-BSAs were mainly delivered to the liver and their hepatic uptake became saturated when the dose was increased. Of these derivatives, only (111)In-Fuc41-BSA showed a slow plasma elimination at low doses, suggesting an interaction with blood components. Examination of binding conditions as well as electrophoretic analysis of the binding components indicated that the serum-type mannan binding protein (MBP) is responsible. Kupffer cells, which possess fucose receptors, showed the highest uptake of (111)In-Fuc41-BSA, followed by endothelial cells and hepatocytes. The hepatic uptake of (111)In-Fuc41-BSA was inhibited by co-injection of Gal42-BSA, but not by Man46-BSA. On the other hand, excess Fuc41-BSA inhibited the hepatic uptake of (111)In-Man46-BSA, while (111)In-Gal42-BSA did not: These findings suggest that not only the fucose receptors on Kupffer cells but also other lectins are involved in the biodistribution of Fuc-BSAs. To understand how the degree of fucose modification affects the binding affinity of Fuc-BSA with hepatic lectins and serum MBP, a pharmacokinetic analysis was performed based on a physiological model. The Michaelis constant of the hepatic uptake of (111)In-Fuc-BSA decreased with an increasing number of fucose units, and the intrinsic hepatic clearance of (111)In-Fuc25-, (111)In-Fuc31- and (111)In-Fuc41-BSAs was close to, or much greater than, the hepatic plasma flow rate, indicating efficient hepatic uptake of these derivatives. These results suggest that fucosylation is a potentially useful method making drug carriers selective for Kupffer cells, although extensive modification might result in retarded delivery due to binding to other lectins like MBP.

Serum mannan binding protein inhibits mannosylated liposome-mediated transfection to macrophages

The effects of serum mannan binding proteins (MBP) in the transfection of plasmid DNA/Man-liposome complex via mannose receptor-mediated endocytosis was studied in vitro using cultured mouse peritoneal macrophages. Plasmid DNA encoding luciferase gene was complexed with cationic mannosylated liposomes (Man-liposomes), composed of cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) and dioleoyl phosphatidylethanolamine (DOPE). The transfection efficiency, as well as the binding and uptake of the plasmid DNA/Man-liposome complex, was investigated with or without serum MBP. The in vitro transfection efficiency of the complex was significantly reduced on increasing the amount of serum MBP. In addition, the cellular association of the complex was also reduced. These results indicate that serum MBP specifically binds to the mannose moieties on the complex and suppresses its cellular uptake, resulting in inhibition of the gene transfection in macrophages. Such an interaction is an obstacle to mannose receptor-mediated in vivo gene transfer to mannose receptor-positive cells using mannosylated gene carriers.

Second-generation intramedullary supracondylar nail for distal femoral fractures

The objective of this study was to review the use of intramedullary supracondylar (IMSC) nails for distal femoral fractures. We reviewed 24 fractures treated with second-generation IMSC nails. The fractures consisted of 18 type A1, one type A2, two type C1, one type C2, and two type C3 fractures. The relationships between clinical results and fracture type, approaches, and patient age were retrospectively reviewed. All fractures healed clinically and radiographically. Twenty-one patients maintained gait performance equivalent to that before injury. Average operating time was 108 min +/- 43 min. ROM in the knee of all patients was -5 degrees +/- 6 degrees in extension and 102 degrees +/- 38 degrees in flexion. Extension lag was influenced by surgical approach. The final knee arc was inversely correlated to patient age (R: 0.49, P<0.05). There were three varus/valgus deformities, two cases with loosening, and two with breakage of the distal locking screws, but no failure of the nail itself. Second-generation IMSC nailing for distal femur fractures was satisfactory in patients younger than 60 years of age.

Quantitative structure/property relationship analysis on aqueous solubility using genetic algorithm-combined partial least squares method

The present study was initiated to generate a model of predicting aqueous solubility of substances from their molecular structure. For 211 drugs or drug-like compounds, their topological indices were calculated by Molconn-Z software. The optimal subset of the descriptors for the prediction of aqueous solubility was determined by genetic algorithm in combination with partial least squares (PLS) method. Thirty-four descriptors were selected by this method. Using 29 of the descriptors selected, of which the scaled PLS coefficient was significant, the cross-validated predictive q2 was 0.785 with 19 principal components that was the optimal and the standard error of prediction was 0.676. Thus, it is suggested that the model obtained would exhibit a good performance in predicting the aqueous solubility of compounds.

Radiographic observation of a case of gastrointestinal stromal tumor in stomach

A case of gastrointestinal stromal tumor (GIST) in stomach was presented. Serial barium meal x-ray examinations revealed an enlarging elevated lesion on the fornix of the stomach. Tumor volume doubling time was found to be 299 days. Microscopic and immunohistochemical studies of the resected tumor disclosed GIST, uncommitted type, low grade malignant/potentially malignant. A radiographic feature of this rare type of gastric submucosal tumor was demonstrated in this report.

Cell-specific delivery of genes with glycosylated carriers

Cationic liposomes and polymers have been accepted as effective non-viral vectors for gene delivery with low immunogenicity unlike viral vectors. However, the lack of organ or cell specificity sometimes hampers their application and the development of a cell-specific targeting technology for them attracts great interest in gene therapy. In this review, the potential of cell-specific delivery of genes with glycosylated liposomes or polymers is discussed. Galactosylated liposomes and poly(amino acids) are selectively taken up by the asialoglycoprotein receptor-positive liver parenchymal cells in vitro and in vivo after intravenous injection. DNA-galactosylated cationic liposome complexes show higher DNA uptake and gene expression in the liver parenchymal cells in vitro than DNA complexes with bare cationic liposomes. In the in vitro gene transfer experiment, galactosylated liposome complexes are more efficient than DNA-galactosylated poly(amino acids) complexes but they have some difficulties in their biodistribution control. On the other hand, introduction of mannose residues to carriers resulted in specific delivery of genes to non-parenchymal liver cells. These results suggest advantages of these glycosylated carriers in cell-specific targeted delivery of genes.

Inappropriate discharges by fourth generation implantable cardioverter defibrillators in patients with ventricular arrhythmias

The study prospectively investigated the incidence, cause and efficient management of inappropriate discharge by the fourth generation implantable cardioverter-defibrillator (ICD) system in 45 patients (mean age, 57+/-16 years). During the follow-up period of 27+/-17 months, 18 patients (40%) experienced one or more inappropriate therapies: sinus and supraventricular tachycardia (15 patients) and T wave oversensing (3 patients). In the 15 patients, re-programming of the tachycardia detection interval and/or additional treatment with beta-blocking agents were effective. In the 3 patients with T wave oversensing, the arrythmia was associated with an increase in T wave amplitude, change in T wave morphology and decreased R wave amplitude, and re-programming of the sensitivity of the local electrogram or changing the number of intervals to detect ventricular tachycardia decreased the number of inappropriate discharges in all 3 patients. In conclusion, inappropriate therapies are common problems in patients treated with the fourth generation ICD system, but most of them can be resolved using the dual-chamber ICD system. However, in patients with T-wave oversensing, it is difficult to avoid inappropriate discharge completely, even if the dual-chamber ICD system is implanted.

QT interval prolongation and torsades de pointes unmasked by intracoronary acetylcholine administration

Intracoronary acetylcholine administration, which was performed to exclude vasospasms, unmasked an abnormal QT interval prolongation and initiated torsades de pointes in a patient with normal QT interval at rest.

Effects of erythrocytes and serum proteins on lung accumulation of lipoplexes containing cholesterol or DOPE as a helper lipid in the single-pass rat lung perfusion system

Plasmid DNA-cationic liposome complexes (lipoplexes) accumulate in the lung to a great extent immediately after intravenous administration, and gene expression occurs predominantly in the lung. However, the detailed mechanisms underlying the lung accumulation of lipoplexes are not fully understood. In this study, we investigated the effect of blood components on the lung accumulation of lipoplexes using a single-pass rat lung perfusion system. Two types of lipoplexes, Chol-containing lipoplex ([(32)P]DNA-DOTMA/Chol liposome complex) and DOPE-containing lipoplex ([(32)P]DNA-DOTMA/DOPE liposome complex), pre-incubated with whole blood, serum, or erythrocytes, were injected into the perfused lung via an artery. Similarly to in vivo observations, extensive lung accumulation was observed for both types of lipoplexes after incubation with whole blood during a single passage. The (32)P-labeled lipoplexes pre-incubated with erythrocytes showed similar lung accumulation, whereas their lung accumulation after incubation with serum was significantly reduced, suggesting that erythrocytes would be more responsible blood components for extensive uptake by the perfused lung. However, there was a clear difference in the amounts of the accumulated erythrocytes after intra-arterial injection between the two lipoplex formulations. A significant degree of erythrocyte accumulation was observed when the DOPE-containing lipoplex was injected, whereas the Chol-containing lipoplex failed to induce any significant erythrocyte accumulation in the lung. In vitro experiments showed that the major fraction of both lipoplexes was bound to erythrocytes. These data suggested that Chol-containing lipoplexes bound to erythrocytes before injection dissociate from the erythrocytes and are transferred to the lung capillary endothelial cells during their passage through the lung. In contrast, DOPE-containing lipoplexes bound to erythrocytes cause aggregation and are embolized in the lung capillary with erythrocytes. Thus, the present study demonstrated that the interaction with erythrocytes plays an important role in the lung accumulation of lipoplexes and that neutral helper lipid significantly affects this interaction.

Transport characteristics of ebastine and its metabolites across human intestinal epithelial Caco-2 cell monolayers

The transport characteristics of a selective peripheral H1 receptor antagonist, ebastine, a substrate for cytochrome P450 3A4, and its three major metabolites, i.e., the hydroxy metabolite of ebastine (M-OH), the pharmacologically active metabolite carebastine (Car), and the desbutyrophenone metabolite (des-BP), were studied in cultured human intestinal Caco-2 cells expressing a drug efflux pump, P-glycoprotein (P-gp), on the apical membrane. The polarized transport of [3H]cyclosporin A (CyA), mediated by P-gp in the basolateral to apical direction across the Caco-2 cell monolayers, was affected by the presence of ebastine in a concentration-dependent manner and significant inhibition was observed at high concentrations (>50 microM). M-OH (300 microM) also significantly inhibited whereas Car and des-BP did not. Although no marked polarized transport of [14C]ebastine in a secretory direction was observed in the Caco-2 systems, the flux in the basolateral to apical direction was slightly higher than that in the opposite direction at concentrations less than 30 microm. [14C]Ebastine (2 microM) uptake from the apical side was significantly increased in the presence of an excess of cold CyA, suggesting that the efflux process mediated by P-gp may be involved in the ebastine uptake by Caco-2 cells. Collectively, these results indicate that ebastine (and presumably M-OH) is transported via P-gp in Caco-2 cells, however, the affinity for P-gp is very low. It is unlikely that the secretory transport of ebastine mediated by P-gp will dramatically affect overall intestinal absorption in vivo because efficient passive diffusion of this drug should occur due to its high lipophilicity. However, it may be advantageous for its efficient first-pass metabolism.

Molecular and pharmacokinetic properties of 222 commercially available oral drugs in humans

This study was performed to determine the exclusion criteria that differentiate poorly absorbed drugs from good drug candidates, and to accelerate drug development by exclusion of unnecessary assessment. The molecular and pharmacokinetic properties of 222 commercially available oral drugs were tabulated and their correlations were analyzed. The exclusion criteria obtained were 1) a molecular weight of more than 500, and 2) a ClogP value of more than 5. Exceptions to molecular weight criteria were compounds with a sugar moiety, high atomic weight, and large cyclic structure. It was also suggested that being a substrate for MDRI (P-glycoprotein) does not always result in poor bioavailability, and that drug development by chemical modification of a seed or lead compound with quantitative structure activity relationship analysis can result in lower bioavailability, higher bound fraction and lower urinary excretion, which would hamper later development processes and might result in considerable drug-drug interaction. The criteria should be adjusted according to the pharmacological profiles of the agents in question and depending on the estimated profit, but ignoring these criteria may result in a significant waste of time and money during drug development.

Enhanced gene transfection in macrophages using mannosylated cationic liposome-polyethylenimine-plasmid DNA complexes

We have previously reported that plasmid DNA and cholesten-5-yloxy-N-(4-[(1-imino-2-beta-D-thiomannosylethyl)amino]butyl) formamide(Man-C4-Chol)/dioleoylphosphatidylethano-lamine(DOPE)(6:4) liposome complexes (DNA/Man-complexes) exhibit efficient gene transfection in macrophages via mannose receptor-mediated endocytosis. To further enhance gene transfetion, polyethylenimine (PEI) was incorporated into this liposome complex (DNA/Man-PEI-complexes), noticing a pH-buffering capacity in endosomes and DNA-condensing activity of PEI. In mouse peritoneal macrophages, the uptake and transfection activity of DNA/Man-PEI-complexes were 2-times and 6-times higher than those of DNA/Man-complexes, respectively. Furthermore, the presence of 1 mg/ml mannan significantly inhibited both the uptake and transfection efficiency of DNA/Man-PEI-complexes. These results suggested that the newly developed multifunctional DNA/Man-PEI-complexes exhibit highly improved gene transfection in macrophages via mannose receptor-mediated endocytosis.

Interaction between DNA-cationic liposome complexes and erythrocytes is an important factor in systemic gene transfer via the intravenous route in mice: the role of the neutral helper lipid

Recent studies have indicated that there are many barriers to successful systemic gene delivery via cationic lipid vectors using the intravenous route. The purpose of this study was to investigate the effect of binding and interaction between erythrocytes, a major constituent of blood cells, and the complexes, in relation to the role of the helper lipid, on the in vivo gene delivery to the lung following intravenous injection. We used three types of cationic lipid vectors, DNA-DOTMA/Chol liposome complexes, DNA-DOTMA liposome complexes, and DNA-DOTMA/DOPE liposome complexes. Although the three types of vectors bind to murine blood cells in vivo and in vitro, DOTMA/Chol and DOTMA complexes with a higher in vivo transfection activity do not induce fusion between erythrocytes, whereas DOTMA/DOPE complexes, a less efficient vector in vivo, induce fusion between the erythrocytes after a short incubation period. Pre-incubation of DOTMA/DOPE complexes with erythrocytes significantly reduced the transfection efficiency while DOTMA/Chol- and DOTMA complexes were more resistant to such treatment. The differences in the physicochemical and structural properties of these complexes could explain the differences in interaction with erythrocytes and subsequent gene expression. Lipids in DOTMA/Chol and DOTMA complexes have a stable lamellar structure. However, lipids in DOTMA/DOPE complexes have a highly curved structure with high fluidity. These results indicate that the interaction with erythrocytes depends on the properties of the cationic lipid vectors and this is an important factor for intravenous gene delivery using cationic lipid vectors.

In vivo recognition of mannosylated proteins by hepatic mannose receptors and mannan-binding protein

In vivo recognition of mannosylated proteins by hepatic mannose receptors and serum mannan-binding protein (MBP) was investigated in mice. After intravenous administration, all three different (111)In-mannosylated proteins were taken up mainly by liver, and uptake was saturated with increasing doses. (111)In-Man-superoxide dismutases and (111)In-Man(12)- and (111)In-Man(16)-BSA had simple dose-dependent pharmacokinetic profiles, whereas other derivatives ((111)In-Man(25)-, -Man(35)-, and -Man(46)-BSA and (111)In-Man-IgGs) showed slow hepatic uptake at <1 mg/kg. Purified MBP experiments in vitro indicated that these derivatives bind to MBP in serum after injection, which interferes with their hepatic uptake. To quantitatively evaluate these recognition properties in vivo, a pharmacokinetic model-based analysis was performed for (111)In-Man-BSAs, estimating some parameters, including the Michaelis-Menten constant of the hepatic uptake and the dissociation constant of MBP, which correlate to the affinity of Man-BSAs for mannose receptors and MBP, respectively. The dissociation constant of Man-BSA and MBP decreased dramatically with increasing density of mannose, but the Michaelis-Menten constant of hepatic uptake of Man-BSA was not so sensitive to the change in density. This suggests that the in vivo recognition of MBP has a stronger cluster effect than that of mannose receptors. Differences obtained here are due to the unique arrangement of carbohydrate recognition domains on each mannose-specific lectin available for mannosylated ligand recognition.

Development of gene drug delivery systems based on pharmacokinetic studies

A series of pharmacokinetic studies following systemic or local administration for the development of delivery systems for gene drugs, such as plasmid DNA and oligonucleotides, are reviewed. The pharmacokinetics of gene drugs after intravenous injection into mice was evaluated based on clearance concepts. Pharmacokinetic analysis revealed that the overall disposition characteristics of the gene drug itself were determined by the physicochemical properties of its polyanionic DNA. Based on these findings, liver cell-specific carrier systems via receptor-mediated endocytosis were successfully developed by optimizing physicochemical characteristics. On the other hand, the pharmacokinetics of gene drugs after intratumoral injection were assessed in a tissue-isolated tumor perfusion system. The relationship between the physicochemical properties of gene drug delivery systems and intratumoral pharmacokinetics was determined and the therapeutic effect was also discussed in relation to pharmacokinetics. Collectively, it was demonstrated that a rational design of gene drug delivery systems that can control their in vivo disposition is possible by means of pharmacokinetic studies at whole body, organ and cellular levels.

Involvement of serum mannan binding proteins and mannose receptors in uptake of mannosylated liposomes by macrophages

The roles of serum mannan binding protein (MBP) and the mannose receptor in the cellular uptake of mannosylated liposomes (Man-liposomes) by macrophages were studied. Man-liposomes were prepared by incorporating cholesten-5-yloxy-N-(4-((1-imino-2-beta-D-thiomannosylethyl)amino)butyl)formamide (Man-C4-Chol) into small unilamellar long circulating liposomes consisting of cholesterol (Chol) and distearoyl phosphatidylcholine (DSPC). In the in vitro cellular uptake study with cultured mouse peritoneal macrophages, [(3)H]Man-liposomes were taken up to a great extent, whereas no significant uptake was observed for [(3)H]cholesterol and DSPC liposomes without Man-C4-Chol (Bare-liposomes). The uptake of [(3)H]Man-liposomes was dose- and temperature-dependent and inhibited by an excess of mannosylated bovine serum albumin, suggesting their specific uptake via membrane mannose receptor-mediated endocytosis. Furthermore, it was demonstrated that (111)In-MBP binds strongly to Man-liposomes based on the recognition of Man-C4-Chol and markedly enhanced their uptake by macrophages. These results are supported by confocal laser microscopic images. In addition, in vivo hepatic uptake of (111)In-MBP was enhanced by Man-liposomes. On the other hand, the uptake of Man-liposomes was significantly reduced by preincubation with serum and further with MBP-depleted serum suggesting inhibitory effects of serum proteins such as albumin on mannose receptor-mediated endocytosis. The involvement of serum-type MBP and membrane mannose receptors in the uptake of Man-liposomes is thus suggested.

Novel galactosylated liposomes for hepatocyte-selective targeting of lipophilic drugs

Novel galactosylated neutral liposomes containing cholesten-5-yloxy-N-(4-((1-imino-2-beta-D-thiogalactosylethyl)amino)butyl)formamide (Gal-C4-Chol) as a "homing" device were developed for hepatocyte-selective drug targeting. Distearoylphosphatidylcholine (DSPC)/cholesterol (Chol) (60:40) and DSPC/Chol/Gal-C4-Chol (60:35:5) liposomes were prepared and labeled with [3H]cholesteryl hexadecyl ether (CHE). [3H]Prostaglandin E1 (PGE1) and [14C]probucol were incorporated in liposomes as model lipophilic drugs. After intravenous injection of the liposomes, mice were sacrificed at suitable time periods, and the lung, liver, kidney, spleen, and heart were excised. DSPC/Chol/Gal-C4-Chol liposomes rapidly disappeared from the blood, and 85% of the dose had accumulated in the liver within 10 min compared with hepatic accumulation of DSPC/Chol liposomes of 12%. The liver was perfused with collagenase, and liver parenchymal cells (PC) and liver nonparenchymal cells (NPC) were separated by centrifugal differentiation to determine the cellular distribution. The PC/NPC ratios for DSPC/Chol/Gal-C4-Chol and DSPC/Chol liposomes were 15.1 and 1.1, respectively. The hepatic uptake of DSPC/Chol/Gal-C4-Chol liposomes, but not that of DSPC/Chol liposomes, was significantly inhibited by the predosing of galactosylated bovine serum albumin. [14C]Probucol and [3H]PGE1 incorporated in DSPC/Chol/Gal-C4-Chol liposomes was also efficiently delivered to the liver. In conclusion, newly developed galactosylated liposomes have been proven to be a useful carrier for hepatocyte-selective targeting that will have many practical applications.

Sequence of events in the glomerular capillary wall at the onset of proteinuria in passive Heymann nephritis

Proteinuria in passive Heymann nephritis (PHN) results from complement-mediated glomerular injury, since complement depletion with cobra venom factor (CVF) prevents proteinuria. However, there are no comprehensive morphological studies identifying the sites of injury leading to onset of proteinuria. To address this issue, we attempted to locate sites of injury involved in the onset of proteinuria in PHN. PHN was induced in intact Munich-Wistar rats (PHN-rats, examined at days 3, 5, and 7) and in complement-depleted rats (CVF treated, PHN-CVF-rats, examined at days 3 and 5). The distribution of endogenous albumin in the glomerular basement membrane (GBM) was studied in in situ drip-fixed glomeruli using immunogold immunocytochemistry, and glomerular anionic sites were visualized by polyethyleneimine staining. In addition, the ultrastructural localization of an epitope recognized by a proteinuria-inducing monoclonal antibody (called 5-1-6) directed against the slit diaphragm was examined. Significant proteinuria was seen in intact PHN-rats, starting at day 5. The intensity of gold labeling for endogenous albumin was significantly increased at the outermost site of the GBM (GBM interfacing foot process and the filtration slit, designated area O) at day 3 in both PHN-rats and PHN-CVF-rats in comparison to untreated controls. At day 5, labeling for albumin in area O was decreased in PHN-rats, but not in PHN-CVF-rats, where it was then higher; in PHN-rats, some areas between epithelial cells and subepithelial deposits were almost free of albumin labeling at day 7. There was no evidence of epithelial cell detachment in any group at day 5, but on day 7 limited focal detachment was seen exclusively in PHN-rats. In proteinuric rats, amorphous material that stained for albumin could be seen in the urinary space, without any exocytosis of labeling by glomerular epithelial cells. A significant reduction of intensity of staining for anionic sites was seen in parallel in both groups, but only in the regions of the lamina rara externa adjacent to subepithelial deposits. This local loss of charge might contribute to enhanced permeability to albumin in both PHN- and PHN-CVF-rats. Changes in the appearance of the filtration slits and in the density and distribution of antigen recognised by monoclonal antibody 5-1-6 were similar in PHN- and PHN-CVF-rats at day 5. Complement depletion prevented neither the reduction in anionic sites of the GBM nor the changes in the slit diaphragm observed. These data suggest that albumin leakage between the epithelial cell and the GBM (area O) could occur in PHN-rats, perhaps as a result of epithelial foot-process changes. This may be the final link in the chain of events responsible for the onset of proteinuria in PHN.

Characterization and subcellular localization of KCNQ1 with a heterozygous mutation in the C terminus

Numerous mutations in KCNQ1, a gene encoding the alpha -subunit of cardiac delayed rectifier potassium channels, have been found in long QT syndrome (LQTS). Among them, several mutations in the C terminus have been shown to cause autosomal recessive or subclinical autosomal dominant LQTS. Here, we report a heterozygous mutation, T587M, which is also in the KCNQ1 C-terminal domain. The same mutation was found in three independent probands that were clearly symptomatic with family history of cardiac sudden death. Functional assay using a heterologous expression system with a mammalian cell line (COS7 cells) revealed that the mutant displayed neither functional channels when expressed alone nor dominant-negative effect when co-expressed with wild-type (WT) KCNQ1. To examine the cellular trafficking of KCNQ1, green fluorescent protein (GFP) was tagged to the cytoplasmic C terminus of WT or mutant KCNQ1. This procedure did not affect the essential properties of expressed WT KCNQ1 channels. On confocal microscopic images, GFP-tagged WT KCNQ1 showed a plasma membrane fluorescence pattern, whereas the GFP-tagged mutant showed a perinuclear fluorescence pattern. Co-expression of the mutant with GFP-tagged WT KCNQ1 did not influence its normal cellular transport. Therefore, the T587M mutant cannot traffic to the plasma membrane and may form no subunit assembly with WT KCNQ1. These findings provide a novel molecular basis for the clinical finding that this C-terminal mutation produced a severe form of RWS-type LQTS.