A novel apolipoprotein E mutation, E2 (Arg25Cys), in lipoprotein glomerulopathy

BACKGROUND

Lipoprotein glomerulopathy (LPG) is characterized by intraglomerular lipoprotein thrombosis and high plasma concentrations of apolipoprotein (apo) E. An apo E variant, apo E2 (Arg145Pro) Sendai, was recently identified in three patients with LPG. We detected a novel point mutation in the apo E gene in a patient with LPG, and we characterized the mutant apo E.

METHODS

The propositus was a 32-year-old male patient on maintenance hemodialysis because of LPG. The mutation was detected by sequencing of genomic DNA from the patient and was confirmed by restriction fragment length polymorphism (RFLP) with Aor51HI. Recombinant apo E2 (Arg25Cys) Kyoto and normal apo E3 were expressed from COS-1 cells. Low-density lipoprotein (LDL) receptor-binding activities of the variants were determined in an in vitro competition assay.

RESULTS

The propositus had the apo E phenotype E2/E4, as determined by isoelectric focusing, and the genotype epsilon3/epsilon4, as determined by RFLP with HhaI. Sequence analysis of amplified DNA showed a C to T transition, changing the codon for residue 25 from arginine to cysteine. The proband was a heterozygous carrier for apo E2 (Arg25Cys) Kyoto. A family study showed that the mother was a heterozygous carrier of apo E2 Kyoto and had dysbetalipoproteinemia, but no LPG. The pathophysiological effect of this mutation was investigated in vitro by binding studies of recombinant apo E2 Kyoto to LDL receptors on human fibroblasts. The ability of recombinant apo E2 Kyoto to displace LDL was reduced to 10% compared with recombinant apo E3.

CONCLUSIONS

Apo E2 (Arg25Cys) Kyoto is a novel mutation of apo E that is etiologically related to LPG. However, our case indicates that the development of LPG may involve other genetic or environmental factors. Furthermore, our data suggest that arginine-25 of apo E plays an important functional role by influencing the receptor-binding ability of apo E.

Protective effect of rebamipide on indomethacin-induced intestinal damage in rats

BACKGROUND AND AIM

We evaluated the effect of rebamipide (2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinon-4-yl] propionic acid), a novel anti-ulcer drug, on indomethacin-induced small intestinal lesions in rats.

METHODS

The animals were administered indomethacin (10 mg/kg, s.c.), and they were killed 24 h later. Rebamipide (30-300 mg/kg) was administered p.o. twice, 30 min before, and 6 h after indomethacin.

RESULTS

Indomethacin caused hemorrhagic lesions in the rat small intestine, accompanied by an increase in enterobacterial translocation, inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) activities, as well as thiobarbituric acid (TBA) reactants, and these changes were significantly prevented by the supplementation with 16,16-dimethyl prostaglandin E2 (dmPGE2; 10 microg/kg, i.v.) or the pretreatment of animals with the antibiotic ampicillin. Treatment of the animals with rebamipide dose-dependently prevented the development of intestinal lesions, and this effect was mimicked by i.v. administration of superoxide dismutase (SOD: 3000 U/kg) + catalase (CAT: 5000 U/kg). The protection by rebamipide was accompanied by a significant suppression of the increase in both MPO and iNOS activities, and a complete inhibition of the increase in TBA reactants, while SOD + CAT significantly inhibited the increase of MPO activity and TBA reactants, but not iNOS activity. The bacterial translocation following indomethacin was also significantly decreased by either rebamipide or SOD + CAT.

CONCLUSION

These results confirmed the importance of enterobacteria and iNOS/NO in the pathogenesis of indomethacin-induced small intestinal lesions, and suggested that rebamipide prevents the development of these lesions, probably by its radical scavenging action.

Protection against dextran sulfate sodium-induced colitis by microspheres of ellagic acid in rats

Ellagic acid (EA), a naturally occurring plant phenol, has the antioxidant and anti-inflammatory activities. In the present study, we examined the effect of EA contained in microspheres on the ulcerative colitis induced experimentally in rats by dextran sulfate sodium (DSS). Experimental colitis was induced in male Fisher 344 rats by daily treatment with 3% DSS solution in drinking water for 7 days. EA of microspheres (mcEA: 1 approximately 10 mg/kg as EA contents) was administered p.o. twice daily for 6 days. In a preliminary study, we found that these microsphere capsules, when administered p.o., are effectively dissolved in the proximal to the ileo-cecal junction and distributed to the terminal ileum and the colon. The ulceration area, colon length, and mucosal myeloperoxidase (MPO) activity as well as thiobarbituric acid-reactive substances (TBARS) were measured on 7th day after the onset of DSS treatment. The DSS treatment for 7 days caused severe mucosal lesions in the colon, accompanied with the increases of MPO activity and TBARS as well as the decreases of body weight gain and colon length. Administration of mcEA reduced the severity of DSS-induced colitis in a dose-dependent manner, and a significant effect was observed at 10 mg/kg, the ED50 being 2.3 mg/kg. This mcEA treatment also significantly mitigated changes in various biochemical parameters in the colonic mucosa induced by DSS. Although plain EA (without using microspheres) was also effective in reducing the severity of DSS-induced colitis, this effect was much less potent as compared with that of mcEA; the ED50 was about 15 times higher than that of mcEA. In addition, a significant effect on DSS-induced colitis was also obtained by intra-rectal administration of superoxide dismutase, an anti-oxidative agent. These results suggest that EA prevents the ulcerative colitis induced by DSS, probably by radical scavenging and/or anti-oxidative actions. The microspheres used in this study may be useful for delivering an orally administered drug specifically to the colon.

Intraglomerular deposition of intact cross-linked fibrin in IgA nephropathy and Henoch-Schönlein purpura nephritis

To investigate the significance of intraglomerular coagulation and fibrinolysis in IgA nephropathy (IgA-N) and Henoch-Schönlein purpura nephritis (HSPN), the distribution of intact cross-linked fibrin (XFb) modulated by plasmin activity was examined in 25 patients with IgA-N and in 12 with HSPN. In addition to the conventional method detecting fibrin-related antigen (FRA) with an antibody against fibrinogen, the enhanced intensity of immunoreactivity of cross-linked FRA (KL-FRA) using the monoclonal antibody DD3B6/22 after plasmin exposure was evaluated to assess intraglomerular deposition of intact XFb. Also, intraglomerular invasion of macrophages was detected using the monoclonal antibody KP1 against CD68. Sixteen of a total of 37 specimens (43%) showed increased intensity of XL-FRA staining after plasmin treatment which is considered to reflect the distribution of intact XFb. Increases in the intensity of XL-FRA staining were observed mainly in mesangium and partially along glomerular capillary loops and also in a few cases in the crescents. The incidence (67%) of increases in XL-FRA staining after plasmin exposure in HSPN specimens was significantly higher than that in IgA-N specimens (32%; p < 0.05). In the group positive for XL-FRA after plasmin exposure, the numbers of macrophages per glomerulus were significantly higher (n = 15; mean +/- SD = 1.6 +/- 0.9) than in the negative group (n = 6; 0.5 +/- 0.6; p < 0.01). In HSPN, the number of macrophages per glomerulus (n = 8; 1.9 +/- 1.0) was higher than that in IgA-N (n = 13; 0.9 +/- 0.9; p < 0.05). Based on these results, we conclude that XFb is often produced and distributed in intact form in the glomeruli both in IgA-N and HSPN, associated with a relatively low intraglomerular plasmin activity, and that intraglomerular coagulation may progress in accordance with macrophage infiltration, especially in HSPN.

Detection of IgA class circulating immune complexes bound to anti-C3d antibody in patients with IgA nephropathy

IgA class circulating immune complexes (CIC) were detected by solid-phase fluorescent enzyme immunoassay of F(ab')2 anti-C3d antibody in the serum of 52 patients with IgA nephropathy. Conglutinin (Kg) binding IgA class CIC were also measured, and results by these assays were compared. Kg binding IgA class CIC and anti-C3d binding IgA class CIC were detected in 27% and 44%, respectively, of the patients with IgA nephropathy. Either or both of the two were found in 65% of the patients. There was no significant correlation between IgA class CIC detected by these methods and serum IgA. Although all samples with a very high level of anti-C3d binding IgA class CIC did not also have a very high level of Kg binding IgA class CIC, there was a slight quantitative correlation between the 2 assays. Ultracentrifugation analysis showed that anti-C3d binding IgA class CIC were of various sizes between polymeric (21 S) and monomeric IgA (7 S), whereas Kg binding IgA class CIC were mostly monomeric IgA (8 S) with a minor component of heavy fractions (14 S). Both IgA class CIC fixed iC3b and IgA class CIC fixed C3d are present in IgA nephropathy. These observations suggest that the different types of complement bound to IgA class CIC have different roles in IgA nephropathy.

An overlapping syndrome of IgA nephropathy and membranous nephropathy?

This is the first report of primary glomerular disease with both mesangial IgA and subepithelial IgG deposits in the glomeruli at the same time. This nephropathy, discovered in 3 patients, is either a new disease entity or an overlapping of IgA nephropathy and membranous nephropathy. Follow-up studies may clarify the pathogenesis of IgA nephropathy and/or membranous nephropathy. In 1 patient the clinical findings resembled those of IgA nephropathy, and in the other 2 they were those of membranous nephropathy. Light microscopy showed generalized diffuse increases in mesangial cells and matrix, and there was slight capillary wall thickening. In the glomeruli, immunofluorescence microscopy demonstrated both granular deposits of IgA in the mesangium and granular deposits of IgG along the capillary loops. On electron microscopy, electron-dense deposits were identified not only in the mesangium but also on the epithelial side of the glomerular basement membrane. These findings were confirmed by the immunoperoxidase technique in electron-microscopic studies of these antibody classes. These glomeruli contained both the dense reaction products of IgA deposits in the paramesangium and mesangial matrix and the dense reaction products of IgG deposits on the epithelial side of the basement membrane.

Demonstration of C3d deposits in membranous nephropathy

An immunoperoxidase technique for light microscopy was carried out in 16 patients with idiopathic membranous nephropathy in order to determine the role of the complement system in glomeruli. Although C3 deposits are found in 50% of the cases, C3d deposits are identified in all cases in association with IgG deposits. This suggests that C3 deposits are degraded and dissociated from immune complexes. Patients with glomerular C3 deposits showed more proteinuria than those without glomerular C3 deposits. The presence of C3 deposits indicates the importance of proteinuria in human membranous nephropathy.

Immunoelectron microscopic studies of IgA nephropathy

Immunoelectron microscopy was used in this study of IgA nephropathy to examine the relationship between immune deposits and electron-dense deposits seen by electron microscopy, and these findings were correlated with the severity of mesangial proliferation. Immunoelectron microscopic studies for antihuman gamma-chain, alpha-chain, mu-chain, C3, and C3d were performed by the method of Nakane in 16 patients with IgA nephropathy. The patients with minimal glomerular involvement and focal proliferative glomerulonephritis showed electron-dense reaction products of IgA in the paramesangial area, while the patients with diffuse proliferative glomerulonephritis showed electron-dense reaction products of IgA throughout the enlarged mesangial matrix. Immunoelectron microscopy showed electron-dense reaction products of IgA at the same locations as the electron-dense deposits seen on electron microscopy. C3 deposits were identified in 15 out of the 16 patients, but were less dense than IgA deposits. Electron-dense reaction products of C3 contained both positive and negative sites in 7 patients. Extensive C3d deposits were found in all cases in association with IgA deposits. The locations of these deposits were the same as those of the IgA deposits. These findings suggest that C3 deposits dissociate from the immune deposits and that the locations of the immune deposits correlate well with the severity of mesangial proliferation.

Analysis of IgG immune complexes in sera from patients with membranous nephropathy: role of IgG4 subclass and low-avidity antibodies

The levels of circulating immune complexes (CIC) were determined using an anti-C3d binding assay in patients with various types of glomerulonephritis (GN). It was found that IgG class CIC were positive in 20% (7/35) of patients with idiopathic membranous nephropathy (MN) and in 80% (8/10) of patients with lupus glomerulonephritis (LN). Of these patients, IgG4 subclass CIC were observed more frequently in 29% of MN and 60% (3/5) of minimum change nephrotic syndrome, and, with less amounts, in 10% (1/10) of membranoproliferative GN (MPGN) and 20% (2/10) of IgA nephropathy. On the other hand, the patients with LN showed a lower positivity (30%) of IgG4-CIC as compared with that of IgG-CIC. In the comparison of mean levels, only MN patients showed significantly higher value than normal individuals (p less than 0.05). In patients with MN, the CIC of the other IgG subclasses (IgG1, IgG2, IgG3) were not significantly elevated and their positivities were low (9-11%). The study on the salt-dependent dissociability of CIC, which is considered to reflect the avidity of antibodies in CIC, showed that the IgG-CIC of 11 of 15 patients with MN were dissociable to various extents even at the physiological concentration. These findings suggested that IgG4 subclass specificity and low avidity may be pathogenic characteristics of IgG-CIC in certain populations of patients with MN.

Mesangiolytic glomerulopathy in severe congestive heart failure

To study the glomerular morphological abnormalities in congestive heart failure (CHF), we analyzed 27 autopsy cases without other causes of renal disease. Their mean age was 59 years, and they showed mild prerenal azotemia. They had generally been treated with digitalis and diuretics, and a few of them with captopril or nifedipine. The abnormal glomerular findings of enlargement, hyperemia, and mesangial thickening were observed at high frequencies (61%, 64%, and 57%, respectively). They characteristically showed mesangiolysis (ML) by the findings of microaneurysms (81%) and mesangial degeneration (70%) such as loose reticular matrix and poor matrix area. In addition, glomerular infiltration of mononuclear leukocytes including macrophages was noted in 70% of the cases. Glomerular enlargement was not correlated with the grade of hyperemia, but it was correlated with the grade of ML index of % glomeruli with microaneurysms (F = 7.22, p < 0.004). There was an inverse relationship between the grades of mesangial thickening and of the ML index (P < 0.005). The number of glomerular leukocytes was positively correlated with mean glomerular size (P < 0.002) and with the ML index (P < 0.03). Notably, the glomerular macrophage-positive cases showed a prominently higher mean ML index than the negative cases (P < 0.005). There was an inverse correlation between the mean glomerular size and the partial oxygen pressure in arterial blood (PaO2; P < 0.01), and a positive correlation between the mean glomerular size and hematocrit (Hct) levels (P < 0.02). The cases positive for mesangiolytic mesangial degeneration showed significantly lower PaO2 values than the cases negative for this lesion (P < 0.04). In the analysis of the various causes of CHF, the patients with congenital cardiac anomalies showed mean levels of the lowest PaO2 (P < 0.02) and the highest Hct (P < 0.03) and histologically the largest mean glomerular size (P < 0.04). There was no difference in the ML index and the glomerular leukocyte number among the subgroups classified by the causes. These results indicate that ML associated with glomerular enlargement is the major glomerular abnormality characteristic in patients with severe CHF and suggest that glomerular infiltration of leukocytes, especially of macrophages, should play an important role in the progression of both ML and glomerulomegaly. The contributions of persistent hypoxia and up-regulated angiotensin II as the causative factors of these glomerular abnormalities in congestive heart failure are discussed.

Relationship of intraglomerular coagulation and platelet aggregation to glomerular sclerosis

In order to investigate the relationship between intraglomerular coagulation and glomerular sclerosis, the distribution of fibrin-related antigen (FRA) in glomeruli without extracapillary lesions was examined by immunoperoxidase microscopy in 80 patients with IgA nephropathy (IgA-N). A total of 302 glomeruli were examined, including 20 with global sclerosis, 31 with segmental sclerosis (SS glomeruli), and 251 nonsclerosed glomeruli. In the nonsclerotic areas of SS glomeruli, the deposition of FRA was significantly greater than in the nonsclerosed glomeruli. In the nonsclerosed glomeruli FRA was mainly found in the mesangium, while in the nonsclerotic areas of SS glomeruli FRA was not only present in the mesangium but also in the endothelium of the glomerular capillary loops. FRA-positive microclots were also often observed attached to the endothelium of the capillaries of the nonsclerotic areas of SS glomeruli. Cross-linked FRA was also observed in the endothelium of the same capillaries using the monoclonal antibody DD3B6/22. Deposition of von Willebrand factor (vWF) was greater in the endothelium than in the mesangium in the same areas. Aggregated platelets adhering to the glomerular capillary walls in these areas were frequently detected using the monoclonal antibody P2. Such distribution of platelets and vWF showed that the endothelium of the nonsclerotic areas of SS glomeruli was more severely damaged than that of nonsclerosed glomeruli. These findings suggest that endothelial cell damage might activate the intraglomerular coagulation, which might be one of the factors in the development of global glomerular sclerosis.

Role of endogenous prostacyclin in gastric ulcerogenic and healing responses--a study using IP-receptor knockout mice

Endogenous prostaglandins (PGs) play an important role in the cytoprotective and healing responses in the stomach, by altering various functions, i.e., an increase of the mucosal blood flow, yet the role of prostacyclin (PGI(2)) and its receptor (IP-receptor) in these responses remains unclarified. In the present study, we used IP-receptor knockout mice [IP (-/-)] and examined the importance of IP-receptors in gastric ulcerogenic, cytoprotective and healing responses in these animals. The studies included the ulcerogenic response to cold-restraint stress, the cytoprotective response to a mild irritant (20 mM taurocholate: TC) and capsaicin, and the healing response of chronic gastric ulcers induced by thermo-cauterization. We first checked the absence of IP-receptors by examining the effect of cicaprost (a PGI(2) agonist, topical mucosal application) on gastric mucosal blood flow and found that this agent increased the mucosal blood flow in wild-type [WT (+/+)] mice but not in IP (+/-) mice. Cold-restraint stress (4 h) induced gastric lesions in both groups of mice, but the severity of damage was significantly greater in IP (-/-) mice. Prior p.o. administration of both TC and capsaicin exhibited a marked cytoprotection against HCl/ethanol-induced gastric damage in WT (+/+) mice, both responses being significantly mitigated in the presence of indomethacin. The adaptive cytoprotection induced by TC was similarly observed in IP (-/-) mice, while the capsaicin protection was totally attenuated in the animals lacking IP receptors. On the other hand, the healing of gastric ulcers was significantly delayed by daily administration of indomethacin in WT (+/+) mice. However, this process was not altered in IP (-/-) mice. These results suggest that endogenous PGI(2) is involved in the gastric ulcerogenic response to stress, but not in the healing of pre-existing gastric ulcers. In addition, PGI(2) and its receptors may play a crucial role in capsaicin-induced gastric protection but not in the adaptive cytoprotection-induced by mild irritants.

A comparative immunologic study of IgA nephropathy

A conglutinin binding assay has been used to detect circulating immune complexes (CIC) containing IgA, IgG, or IgM in sera from patients with IgA nephropathy. IgA class CIC were detected in 40.7% of patient. IgG class CIC were detected only in patients with glomercular IgG deposits. IgM class CIC were detected more often in patients with glomerular IgM deposits than in patients without glomerular IgM deposits. These results demonstrate an association between the immunoglobulin in CIC and those in glomerular deposits. CIC were not detected in sera from most patients with IgA nephropathy by a Clq binding assay, however, since this assay does not detect IgA class CIC. Immunoelectronmicroscopic studies of IgA nephropathy have shown that C3 deposits are localized to the same areas as IgA deposits. In conclusion, we suggest that mesangial IgA deposits are composed of immune complexes and may be derived from CIC.

Circulating immune complexes of IgG, IgA, and IgM classes in various glomerular diseases

In order to examine the correlation between immunoglobulin (Ig) classes of immunoglobulins in circulating immune complexes (CIC) and immunoglobulins in glomerular deposits, we have measured CIC of IgG, IgA and IgM classes in various glomerular diseases. Serum CIC were measured using a modified conglutinin binding assay (K assay) using 125I-labeled anti-gamma, anti-alpha and anti-mu antisera. IgA class CIC were detected in more patients with IgA nephropathy than patients with non-IgA nephropathy. There was an association between the presence of IgG deposits in kidneys and the presence of IgG in CIC. Patients with IgA deposits in their kidneys also had IgA class CIC. There was also an association between the presence of IgM deposits in kidneys and the presence of IgM in CIC. These results suggest that the Ig class in CIC and the Ig class in glomerular deposits were correlated, and that in IgA nephropathy the mesangial IgA deposits may be derived from IgA class CIC.

Immunoelectron microscopic localization of fibrin-related antigen in human glomerular diseases

The distribution of fibrin-related antigen (FRA) in glomeruli was examined by immunoelectron microscopy in 9 patients with idiopathic membranous nephropathy (MN), 8 patients with minimal-change nephrotic syndrome, and 10 patients with IgA nephropathy (IgA-N), using antisera against human gamma--chain, alpha-chain, mu-chain, and fibrinogen. Electron-dense reaction products of FRA were observed in the endothelium, subendothelium, and/or in electron-dense deposits (EDD). Among the three glomerular diseases, the amount of electron-dense reaction products of FRA in the endothelium was highest in MN. This suggests that coagulation occurs on the endothelium in MN. Although the mesangial EDD of IgA-N were intensely stained with reaction products of FRA, the staining was weak in the subepithelial EDD of MN. This suggests that FRA hardly penetrates into the subepithelial EDD in MN.

Effect of taurine on ulcerogenic response and impaired ulcer healing induced by monochloramine in rat stomachs

BACKGROUND

It is well known that neutrophil-derived hypochlorous acid interacts with ammonia (NH4OH) to generate monochloramine (NH2Cl) and that NH2Cl irritates the gastric mucosa and impairs ulcer healing.

AIM

To examine the effect of taurine, a hypochlorous acid scavenger, on the mucosal ulcerogenic and the impaired healing response induced by NH2Cl in rat stomachs, in comparison with those of methionine and glycine.

METHODS AND RESULTS

Under anaesthesia, oral administration of NH2Cl (120 mmol/L) produced severe lesions in male Sprague-Dawley rat stomachs. Taurine (10-100 mg/kg) given p.o. 30 min prior to NH2Cl dose-dependently prevented these lesions in response to NH2Cl. This action was mimicked by methionine (3-30 mg/kg) but not by glycine (10-100 mg/kg). Under urethane anaesthesia, mucosal exposure to NH4OH (120 mmol/L) caused a marked reduction of potential difference (PD) in the ex vivo chambered stomachs after induction of ischaemia, resulting in severe lesions. These ulcerogenic and PD responses by NH4OH plus ischaemia were also mitigated by taurine and methionine, but not glycine, applied to the chamber 20 min before the onset of NH4OH plus ischaemia. Moreover, oral administration of 100% ethanol produced severe haemorrhagic lesions in rat stomachs, all of which rapidly healed within 7 days after lesion induction. Daily administration of NH2Cl (20 mmol/L) significantly delayed the healing of these lesions, but recovery of this impaired healing response was obtained by concurrent administration of taurine. Both taurine and methionine showed a potent scavenging effect against NH2Cl in vitro.

CONCLUSIONS

(1) NH2Cl generated either exogenously or endogenously damages the gastric mucosa and impairs the healing response; (2) taurine exerts a prophylactic effect against the deleterious effects of NH2Cl, mainly due to its scavenging action against NH2Cl; and (3) this effect of taurine may be useful for treatment of gastritis associated with Helicobacter pylori infection.

Clinicopathological study of patients with mesangial isolated C3d deposition in various glomerular diseases

The clinicopathological findings of isolated mesangial C3d deposition in the absence of other complement components or immunoglobulins are summarized. 55 out of 242 individual human renal biopsies examined by immunoperoxidase microscopy had isolated C3d deposition. This group consisted of 12 patients with chronic glomerulonephritis, 8 with minimal-change nephrotic syndrome, 32 with benign recurrent hematuria, 2 with Bartter's syndrome and 1 with Raynaud's syndrome. None of these patients had a disorder of the renal function and in all the patients the disease took a benign clinical course. Light-microscopic findings indicated injuries ranging from minor glomerular abnormality to mild diffuse mesangial proliferative glomerulonephritis, and there were no other remarkable findings such as cellular crescents, global sclerosis or interstitial infiltration. By immunoperoxidase microscopy, fine granular deposits of C3d were identified only in the mesangium, and arteriolar C3 staining was seen in 31 of the 55 patients. In 38 of the 42 patients examined by electron microscopy, electron-dense deposits were identified in the mesangial matrix. These findings suggest that isolated C3d deposition is a new entity with benign features both clinically and pathologically.

Infected abdominal aortic aneurysm due to Salmonella: CT evaluation

Two cases of infected abdominal aortic aneurysm (IAAA) caused by salmonella are reported and the computed tomography (CT) features are discussed and compared with the pathologic findings. Additionally, a review of the literature was performed. A well-enhanced para-aortic mass (PAM) beyond the calcified intima of the abdominal aorta on the CT, which was initially considered to represent a leakage from the infected aneurysm, was observed in 5 of the 6 reported cases (including ours) and identified as a pseudoaneurysm. In one case, multiple gas collections within the PAM were demonstrated for the first time in IAAA due to salmonella.

Cryoactivation of inactive renin in human plasma

The mechanism of the increase in renin activity in human plasma which had been kept -5 degrees C for 4 days (cryoactivation) was investigated. From the results of clinical studies, it is likely that the controling mechanism of inactive renin has something in common with that of active renin. The experimental data showed that the increase in renin activity of human plasma by cryoactivation was closely correlated to the increase obtained by incubation with trypsin (r = 0.88, p less than 0.001, n = 10). Soybean trypsin inhibitor, aprotinin and di-isopropylfluorophosphate (DFP) inhibited cryoactivation, indicating that the cryoactivation is due to the action of a trypsin-like serine enzyme. Trypsin which had no effect on plasma renin activity in the presence of the same amount of soybean trypsin inhibitor at 37 degrees C, activated the renin activity during cold incubation, suggesting that the dissociation of the trypsin-inhibitor complex may have taken place at a low temperature. Endogenous trypsin inhibitor is also likely to lose its affinity to endogenous trypsin-like enzyme at a low temperature.

An adult-onset case of argininosuccinate synthetase deficiency presenting with atypical citrullinemia

A 52-year-old heavy drinker presented with repeated episodes of disturbance of consciousness and an increase in serum ammonia level, triggered by excessive alcohol intake. He was diagnosed as having adult-onset citrullinemia with deficiency of hepatic argininosuccinate synthetase (ASS) activity. Cranial magnetic resonance imaging (MRI) showed high-intensity lesions in the central pons and the bilateral middle cerebellar peduncles on T2-weighted images. Although almost all cases of adult-onset citrullinemia have been reported to be enzymologically classified as type II, the serum amino acid pattern and serum level of human pancreatic secretory trypsin inhibitor (hPSTI) were atypical for type II in the present case.

High level of plasma inactive renin in Bartter's syndrome

In 10 cases of Bartter's syndrome, plasma active and inactive renin (AR and IR) were measured by two different methods. First, plasma renin activity (PRA), and total renin activity (TRA) after activating IR with trypsin, were measured by radioimmunoassay (RIA) of angiotensin I (AI) generated from endogenous substrate. And secondly, plasma active renin concentration (ARC) and total renin concentration (TRC) were measured by RIA of AI generated in the presence of an excess of exogenous substrate. The difference between TRA and PRA, and between TRC and ARC were designated as inactive renin activity (IRA) and inactive renin concentration (IRC), respectively. Small amounts of IRA were found only in 2 cases and no IRA in 8 cases. However, the existence of large amounts of IR in Bartter's syndrome was revealed by the IRC determination. This suggests that the shortage of endogenous renin substrate, consumed by the markedly increased AR, may have interfered with the detection of IRA in Bartter's syndrome, though the IR is markedly increased as well. The molecular weights of AR and IR were determined by Sephadex G-100 gel filtration in 3 cases. Both AR and IR seemed to be smaller than those of normal subjects.

Ultrastructural distribution of von Willebrand factor in human glomerular diseases

The distribution of the von Willebrand factor (vWF) as the factor-VIII-related antigen in glomeruli was examined by immunoelectron microscopy in 10 patients with idiopathic membranous nephropathy (MN), 8 patients with minimal-change nephrotic syndrome (MCNS), and 11 patients with IgA nephropathy (IgA-N). Electron-dense reaction products of vWF were observed in the endothelium and mesangium in all specimens examined. However, they were not detected in subepithelial electron-dense deposits of MN. The amount of electron-dense reaction products of vWF in the endothelium was significantly higher in MN than that in MCNS or IgA-N. This finding suggests that the glomerular endothelium in MN is the site of the local activation of coagulation and platelet aggregation system in glomerular capillary wall lesions.