Genetic analysis of the epithelial sodium channel in Liddle's syndrome

BACKGROUND

Liddle's syndrome is an autosomal inheritable disorder that causes hypertension due to excess function of sodium channel.

OBJECTIVE

To analyze the DNA sequence of the amiloride-sensitive epithelial sodium channel (ENaC) in three patients who had low-renin hypertension with hypokalemia. The patients included a 24-year-old woman and her 20-year-old brother whose mother was hypertensive. The third patient was a 15-year-old girl with no family history of hypertension.

METHODS

The DNA sequence of the ENaC was analyzed as follows. Venous blood samples were collected from the patients and total genomic DNA was prepared by standard methods. Specific primers were used for direct polymerase chain reaction; one set of primers for amplifying the C terminus (codon 523-638) of the , subunit of ENaC, and two sets of primers for amplifying the C terminus (codons 525-587 and 568-650) of the y subunit of ENaC. Polymerase chain reaction products were purified and subjected to direct DNA sequence analysis.

RESULTS

Direct sequence analysis demonstrated the presence of a single-base substitution in one segment of the 0 subunit of ENaC, a C-T transition that changed the encoded Pro (CCC) at codon 616 to Ser (TCC) in the siblings (cases 1 and 2). In case 3, we found a missense mutation of Pro (CCC) to Leu (CTC) at codon 616. Case 3 is considered to be sporadic, since DNA sequencing of the PY motif of her parents gave normal results.

CONCLUSIONS

The DNA sequences of the ENaC in three patients with Liddle's syndrome were analyzed. In one family case, we found a new missense mutation of Pro (CCC) to Ser (TCC) at codon 616 in the 0 subunit of ENaC. A genetic analysis of the amiloride-sensitive epithelial sodium channel is recommended in assessing patients with low-renin, salt-sensitive hypertension whose blood pressure is not responsive to spironolactone treatment.

Effect of sorbitol dehydrogenase inhibition on sugar cataract formation in galactose-fed and diabetic rats

Several recent studies with the sorbitol dehydrogenase inhibitors 4-[4-(N,N-dimethylsulfamoyl)-piperazino]-2-methylpyrimidine, SDH-1, and its active metabolite 4-[4-(N, N-dimethylsulfamoyl)piperazino]-2-hydroxymethylpyrimidine , SDH-2, suggest that inhibition of sorbitol dehydrogenase may be beneficial in delaying the onset of diabetic complications due to their ability to ameliorate redox changes associated with polyol metabolism. To compare the relative importance of sorbitol dehydrogenase versus aldose reductase inhibition on sugar cataract formation, cataract formation was monitored in 50% galactose-fed and diabetic rats treated with/without the sorbitol dehydrogenase inhibitors SDH-1 or SDH-2 or the aldose reductase inhibitors AL 1576 or Ponalrestat. For these studies, diabetes was induced in young 50 g rats with streptozotocin while galactosemia was produced by feeding a diet containing 50% galactose. Inhibitors were administered in the diet with the diet containing 0.06% (w/w) of the sorbitol dehydrogenase inhibitors or Ponalrestat, and 0.0125% (w/w) of AL 1576. Cataract formation was monitored by hand-held slit lamp and polyol levels were measured by gas chromatography. Sugar cataract formation was accelerated in diabetic rats treated with sorbitol dehydrogenase inhibitors while no difference in cataract formation was observed in galactose-fed rats treated with/without SDH inhibitors. Cataract formation was inhibited in both diabetic and galactosemic rats by either Ponalrestat or AL 1576. These results support the concept that sugar cataract formation is initiated by the aldose reductase catalysed intracellular accumulation of polyols and that these sugar cataracts can be prevented through inhibition of aldose reductase.

[Evaluation by MR imaging of neoadjuvant intra-arterial infusion chemotherapy in uterine cervical cancer]

Eight patients with uterine cervical cancer received two or three courses of neoadjuvant chemotherapy, including 254-S i.v. and CDDP i.a. Transcatheter arterial embolization (TAE) was added for seven patients. The therapeutic efficacy was evaluated by MR imaging and postoperative histopathological examination. Three patients achieved a complete response (CR) and five others were evaluated as a partial response (PR) on MR imaging. On postoperative histology, three of eight showed CR or PR, which coincided with MR findings. Viable cancer cells were shown in five patients. To detect these viable tumors, dynamic MR imaging was indispensable. However, because of limited spatial resolution, the detection of small residual tumors was not easy using dynamic MR imaging.

A family with Liddle's syndrome caused by a new missense mutation in the beta subunit of the epithelial sodium channel

Liddle's syndrome is an autosomal dominant form of salt sensitive hypertension caused by mutations in the beta or gamma subunit of the epithelial sodium channel. Systematic mutagenesis studies revealed that a conserved PPPXY sequence (PY motif) of the C-terminus of the alpha, beta, or gamma subunits might be involved in the regulation of the channel activity. However, only two missense mutations in the PY motif of the beta subunit have been reported to cause Liddle's syndrome. We sequenced the C-termini of the beta and gamma subunits of the epithelial sodium channel in a Japanese family clinically diagnosed as having Liddle's syndrome and found a new missense mutation in the PY motif of the beta subunit, P615S. Expression studies with P615S mutant in Xenopus oocytes resulted in an about 3-fold increase in the amiloride-sensitive sodium current compared to the wild type (p = 0.001). These findings provide further clinical evidence for the hypothesis that a conserved PY motif may be critically important for the regulation of the epithelial sodium channel.

New diagnostic peritoneal lavage criteria for diagnosis of intestinal injury

BACKGROUND

Although diagnostic peritoneal lavage (DPL) is a well-established, reliably objective method of diagnosis of intraperitoneal injury, it is too sensitive to be used as an indicator for emergency celiotomy. Therefore, since the development of ultrasonography and advanced computed tomographic scanners, the role of DPL has been markedly reduced. Despite such remarkable advances, however, radiologic diagnosis of intestinal injury cannot always provide definitive results, and DPL may still be valuable in such instances. We have developed a new DPL criteria specifically designed to aid in the diagnosis of intestinal injury and have evaluated its effectiveness.

METHODS

From August 1988 to December 1995, we performed DPL in 250 patients with blunt abdominal trauma and analyzed the diagnostic accuracy of our new criteria. We used the standard quantitative white blood cell (WBC) criterion for detection of intestinal injury supplemented by a positive-negative borderline adjusted to WBC > or = red blood cell (RBC)/150, where RBC > or = 10 x 10(4)/mm3.

RESULTS

Our criteria had a diagnostic sensitivity of 96.6% and a specificity of 99.4% for intestinal injury after exclusion of 57 patients in whom DPL was performed within 3 hours or after 18 hours from the time of injury. In 133 patients with hemoperitoneum, emergency celiotomy was performed in only 48; the remaining 85 patients with negative DPL based on the WBC criterion avoided surgery, and conservative management resulted in no complications.

CONCLUSION

With the proposed criteria, DPL can be used to diagnose or exclude intestinal injury even in the presence of hemoperitoneum.

Multiple DNA elements for sterol regulatory element-binding protein and NF-Y are responsible for sterol-regulated transcription of the genes for human 3-hydroxy-3-methylglutaryl coenzyme A synthase and squalene synthase

The expression of the human SREBP-2 gene is transcriptionally regulated in a cooperative manner by sterol regulatory element-binding proteins (SREBPs) and the general transcription factor NF-Y [Sato, R., Inoue, J., Kawabe, Y., Kodama, T., Takano, T., and Maeda, M. (1996) J. Biol. Chem. 271, 26461-26464]. To understand the sterol-dependent transcriptional regulation by these factors in detail, we have examined the regulation of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) synthase and squalene synthase genes, whose promoters have multiple potential sterol regulatory elements (SRE, SREBP binding site) and NF-Y binding sites. The promoter of the human HMG CoA synthase gene was cloned, sequenced, and functionally characterized by means of reporter gene assays. The results indicate that an inverted CCAAT box, two SRE motifs and two Sp1 sites localized in a 90-bp region coordinately regulate the transcription. In the case of the human squalene synthase promoter, two SRE motifs and an inverted CCAAT box between the motifs localized in a 51-bp region are responsible for the sterol-regulated transcription of the gene. Gel mobility shift assay reveals that these two inverted CCAAT boxes are recognized by NF-Y. The involvement of multiple responsive elements in the transcription of HMG CoA synthase and squalene synthase seems to induce a higher level of sterol-dependent regulation (3.5 to 5. 8-fold) compared with that of the SREBP-2 promoter, which contains a single pair of SRE motif and CCAAT box (1.8 to 2.6-fold). Reporter gene assays using constructs containing various nucleotide spacing lengths between the SRE motif and the CCAAT box demonstrate that the 16 to 20-bp spacing range is required for maximal transcriptional regulation. These results agree with the findings that the distances between the two motifs in the known sterol responsive elements in several genes, including the human HMG CoA synthase and squalene synthase genes, are in this range.

Proton transfer in benzyl alcohol dehydrogenase during catalysis: alternate proton-relay routes

His51 in horse liver alcohol dehydrogenase (ADHE) has been proposed to act as a proton donor/acceptor in the NAD+/NADH-dependent oxidation/reduction of alcohol/aldehyde. The residue corresponding to His51 of ADHE is Val51 (Val45 in the protein sequence) in benzyl alcohol dehydrogenase (BADH) encoded by TOL plasmid pWW0. The 3-D structure of BADH modeled from the crystal structure of ADHE suggests that His47 (His41 in the protein sequence, corresponding to Arg47 in ADHE) of BADH would play the role of His51 in ADHE. To test this hypothesis, mutants of BADH, in which His47 was replaced by Gln(His47Gln) and/or Val51 was replaced by His (Val51His), were constructed. The kcat/K(m) value of the His47Gln mutant for benzyl alcohol was 125-fold lower than that of wild-type BADH, while the kcat/K(m) value of the His47Gln/Val51His double mutant was 12-fold higher than that of the His47Gln mutant. The kcat/K(m) value of the His47Gln mutant increased with increasing concentration of exogenous amines. These results suggest that His47 in wild-type BADH, exogenous amines in the His47Gln mutant, and His51 in the double mutant act as a general base catalyst during alcohol oxidation.

[Arterial infusion of SMANCS-Lipiodol for advanced hepatocellular carcinoma]

Twenty-four patients were treated with arterial infusion of SMANCS dissolved in Lipiodol. Twenty of these patients had HCC with the main trunks of portal vein occluded by tumor, and four patients had severe cirrhosis and multiple HCC. The actual dose of SMANCS administered each patient ranged from 4 to 6 mg. Side effects occurred in 50%. Severe side effects such as shock and shivering-chilliness were observed in 18%. The differences between the values of hepatic functional serum indexes obtained before and after treatment with SMANCS were small and transient. With regard to the therapeutic response of the arterial infusion of SMANCS, the mean survival time was approximately 2.8 months. It was suggested that the more effective administration of SMANCS was combination of the arterial infusion of SMANCS-Lipiodol with TAE at the level of the right hepatic artery of left hepatic artery for multiple HCC.

A novel domain in the CD30 cytoplasmic tail mediates NFkappaB activation

About 100 amino acid residues in the C-terminal region are conserved among human, rat and murine CD30, a member of the tumor necrosis factor receptor (TNFR) superfamily, and can be separated into three subdomains with relatively higher conservation (D1, D2 and D3). Activation of NFkappaB by CD30 was shown to be mediated through interaction of TNFR-associated factor (TRAF) 1, 2 and 5 with the D2 and D3 subdomains. However, the function of the other conserved subdomain, D1, remained to be determined. Deletion of the D2 and D3 subdomains abolished interactions with TRAF2 and 5 but it did not affect NFkappaB activation. Reporter gene assays using deletion and mutant constructs of CD30 revealed that the D1 subdomain is sufficient for NFkappaB activation, without interaction with TRAF2 or 5, and that each subdomain alone can activate NFkappaB. Electrophoretic mobility shift assays revealed constitutive and CD30-induced NFkappaB activation in stable transformants of 293 cells expressing CD30 or a deletion mutant lacking D2 and D3 subdomains. Deletion of C-terminal 19 amino acid residues of the D1 subdomain abolished activation of NFkappaB. Substitution of alanine for one of the two threonine residues (amino acid position 524 and 529), one of which is a potential phosphorylation site in the D1 subdomain, also abolished the NFkappaB activation. Overexpression of the TRAF domain of TRAF2 or 5 had a dominant negative effect on the NFkappaB activation mediated by the D1 subdomain, thereby suggesting involvement of TRAF proteins in the signaling. Thus, the C-terminal 100 amino acid region of CD30 is composed of three independent functional subdomains, two of which contain binding sites for TRAF proteins. A novel domain in the cytoplasmic tail mediates NFkappaB activation, without direct interaction of TRAF2 or 5. Our observations suggest involvement of an unknown TRAF protein(s) in the signal transduction pathway of CD30.

Cloning and characterization of a cDNA encoding the human homolog of tumor necrosis factor receptor-associated factor 5 (TRAF5)

A cDNA encoding the human homolog of the tumor necrosis factor receptor-associated factor 5 (TRAF5) protein has been molecularly cloned from a cDNA library of Human Daudi B cell line. The sequence analysis revealed that the cDNA encoded a protein of 557 aa residues with a calculated molecular weight of 64,236. The encoded protein has typical structural characteristics shown in the TRAF family of proteins and binds to the cytoplasmic region of lymphotoxin-beta receptor more efficiently than to that of CD40 and CD30. The TRAF5 gene was mapped to the human chromosome 1q32.3-q41.1. Overexpression of human TRAF5 activates NF kappa B transcription factor in human 293T kidney cells. These results suggest that the human TRAF5 protein could be involved in the signal triggered by various members of the tumor necrosis factor receptor (TNFR) superfamily including CD40, CD30 and lymphotoxin-beta receptor.

Endothelin-1 inhibits endothelin-converting enzyme-1 expression in cultured rat pulmonary endothelial cells

BACKGROUND

The lung expresses large amounts of endothelin-converting enzyme-1 (ECE-1), which catalyzes a step in the biosynthesis of potent vasoactive endothelin-1 (ET-1) from the inactive intermediate big ET-1. Because there has been no report concerning a possible relationship between ET-1 and ECE-1, we investigated the effects of ET-1 on ECE-1 expression in cultured rat pulmonary endothelial cells.

METHODS AND RESULTS

ECE-1 messenger RNA (mRNA) and protein expression in cultured endothelial cells were assayed by Northern and Western blotting, respectively. Incubation with ET-1 for 6 hours caused a significant decrease in ECE-1 mRNA expression. The action of ET-1 on ECE-1 mRNA expression was antagonized by pretreatment with BQ788, a specific ETB receptor antagonist, but not by pretreatment with BQ123, a specific ETA receptor antagonist. The expression of ECE-1 protein was also inhibited at 6 hours after incubation with ET-1. The effects of ET-1 on ECE-1 mRNA and protein expression were shown to be mimicked by ionomycin, a calcium ionophore, but not by 12-O-tetradecanoylphorbol 13-acetate, a protein kinase C activator.

CONCLUSIONS

The present results demonstrate that ET-1 suppressed ECE-1 protein levels by inhibiting ECE-1 mRNA expression through the ETB receptor, suggesting the existence of a feedback action of ET-1 on ECE-1 in pulmonary endothelial cells.

Identification and expression of the Xenopus homolog of mammalian p100-NFkappaB2

We have molecularly cloned a cDNA encoding a new Rel-related protein in Xenopus laevis. The product is most homologous to mammalian p100-NFkappaB2. Furthermore, the putative protein kinase A-phosphorylation site (RRPS), which is found in most of the Rel family proteins and is replaced by KRKR in mammalian p100, is also replaced by KRKK in our clone, indicating that our cDNA most likely encodes the Xenopus p100 (Xp100). Like mammalian p52, a processed product of p100, Xp52 alone binds to the kappaB site but does not activate transcription, while the XRelB/Xp52 heterodimer activates transcription, which is inhibited by the carboxyl-terminal half of Xp100 (XIkappaBdelta). Xp100 transcripts are present at all stages of oocyte maturation and in all adult tissues examined. Xp100 transcripts decrease at the gastrula stage and resume their expression at the neurula stage, which is different from other Xenopus rel family. Xp100 is highly expressed in somitogenic mesoderm at the neurula stage, while in the gastrula and tailbud stages, Xp100 transcripts are not localized to restricted regions. These results suggest that Xp100 could be involved in the late-stage development of Xenopus laevis, especially in the maturation of somites.

Induction of interleukin-12 p40 transcript by CD40 ligation via activation of nuclear factor-kappaB

Interleukin-12 is produced in response to infection with bacteria or parasites or to bacterial constituents such as LPS in monocytes/macrophages and dendritic cells, and also generated by the interaction between activated T cells and antigen-presenting cells via CD40-CD40 ligand (CD40L). So far, transcriptional analyses of p40 have been carried out only using bacterial constituents such as LPS as stimuli. In the present study, we have characterized the transcriptional induction of p40 by CD40 ligation in a human B lymphoblastoid cell line, Daudi, and a human acute monocytic leukemia cell line, THP-1. These cells, stimulated by an agonistic monoclonal antibody against CD40 or by transfection with a CD40L expression vector, secreted p40 and showed enhanced p40 mRNA expression. Sequence analysis of the p40 promoter region identified two potential nuclear factor (NF)-kappaB binding sites conserved between mouse and human. Electrophoretic mobility shift assay revealed that the potential NF-kappaB binding sequence which is located around 120 bp upstream of the transcription initiation site in murine and human p40 genes formed an NF-kappaB complex with nuclear extract from Daudi cells stimulated by CD40 ligation. Moreover, transfection of Daudi cells with the polymerized NF-kappaB binding sequence ligated to a thymidine kinase/chloramphenicol acetyltransferase (CAT) reporter plasmid greatly induced CAT activity, but transfection with the polymerized mutated NF-kappaB binding sequence did not. These results suggest that the NF-kappaB binding site located around 120 bp upstream of the transcription initiation site in murine and human p40 promoter regions could be important for the p40 induction by CD40 ligation via activation of NF-kappaB.

Effects of intermittent administration of low dose human PTH(1-34) on cancellous and cortical bone of lumbar vertebral bodies in adult beagles

This study assessed the effect of low dose human parathyroid hormone [hPTH(1-34)] administration on cancellous and cortical bone of lumbar vertebrae in intact male beagles. 16 19-20-month-old beagle dogs were randomized into four groups: in group 1, the vehicle control group, saline was injected daily; in group 2, the sequential group, 0.375 microg/kg of PTH was injected daily for 4 weeks, then off 8 weeks, and this sequence was once repeated for another 4 and 8 weeks; in group 3, the same dose of PTH was injected once per week for 24 weeks; and, in group 4, PTH was injected three times per week for 24 weeks. Histomorphometric assessment on cancelllous and cortical bone (both ventral and dorsal shell) and two-dimensional node-strut analysis were done on the fifth lumbar vertebral bodies after calcein double bone labeling. In intact adult beagles, on the group treated with 0.375 microg/kg per day three times per week (group 4): (1) had a higher mean value in cancellous bone formation parameters [osteoid surface (+74%), osteoid volume (twofold), mineral apposition rate (+21%), and bone formation rate (twofold)]; (2) exhibited no effect on cortical thickness and porosity in both the ventral and dorsal shell; and (3) showed a lower mean value of node to termini (0.11 +/- 0.02 vs. 0.22 +/- 0.09) and a higher mean value of cortex to node (0.18 +/- 0.06 vs. 0.08 +/- 0.02), but not in trabeculae to trabeculae node, than age-related controls. In conclusion, we found that a low dose of PTH administration: (1) stimulated cancellous bone formation; (2) improved connectivity of trabeculae joined to the cortex; (3) did not decrease cortical thickness; and (4) did not increase cortical porosity in both ventral and dorsal cortexal shell of the lumbar vertebrae during this dosage and period in intact male beagles.

Mouse germinal center B cells with the xid mutation retain responsiveness to antimouse CD40 antibodies but diminish IL-5 responsiveness

The germinal center (GC) develops in secondary lymphoid tissues in response to thymus-dependent (TD) antigens. To investigate the molecular mechanism of B cell differentiation in GC, we enriched GC B cells from spleen of TD antigen-immunized wild-type and X-linked immunodeficient (XID) mice, and examined the differentiation of GC B cells into antigen-specific IgG1 antibody-forming cells (AFC) in response to anti-CD40 mAb and cytokines. A significant proportion of freshly purified GC B cells expressed receptors for IL-4 and IL-5. Anti-CD40 mAb sustained the viability of GC B cells and IL-4 co-operated with anti-CD40 mAb for further enhancement of the cell viability. Anti-CD40 mAb and IL-4 were essential for inducing differentiation of GC B cells into antigen-specific IgG1-AFC and IL-5 efficiently enhanced their differentiation. GC B cells with the xid mutation responded for proliferation to CD40 ligation to a lesser extent and for the IgG1-AFC response to anti-CD40 mAb together with IL-4, but they showed impaired responsiveness to IL-5, regardless of enhanced expression of IL-5R in response to anti-CD40 mAb and IL-4. These results suggest that anti-CD40 mAb, IL-4 and IL-5 play a critical role in the differentiation of mouse GC B cells. The GC B cells from XID mice show a functional defect with respect to IL-5-mediated differentiation.

A novel zinc finger protein, Finb, is a transcriptional activator and localized in nuclear bodies

cDNAs encoding a novel DNA binding protein, termed Finb (finger protein in nuclear bodies) were molecularly cloned. The Finb protein consists of 1656 amino acids, containing 15 C2H2-type zinc fingers and three proline-rich regions. Finb efficiently activates transcription from the promoters of the metallothionein and thymidine kinase genes. The finb mRNA is ubiquitously expressed in various cell lines and tissues. The protein product is localized in nuclear bodies, whereas the N-terminally truncated protein spreads throughout the nucleus and cytoplasm. Further characterization of Finb would unravel an important role of nuclear body-involved transcriptional regulation.

Retinoblastoma binding factor 1 site in the core promoter region of the human RB gene is activated by hGABP/E4TF1

We previously reported two oncogenic point mutations present in the RB (retinoblastoma) gene promoter region, found at consensus Sp1 and ATF sites, respectively, and in two separate hereditary RB families. However, Sp1 protein was shown not to bind to the Sp1 site; this indicated that the Sp1 consensus site mutation was blocking the action of an alternative transcription factor, which we called RBF-1 (retinoblastoma binding factor 1). Subsequent purification of RBF-1 revealed it to be hGABP/E4TF1, a transactivator from the adenovirus early-region 4 promoter. In this study, we directly examined the effects of hGABP/E4TF1 on transactivation of the RB gene promoter through the RBF-1 site. As expected, hGABP/E4TF1 enhanced the core RB promoter activity, whereas it did not stimulate a mutant RBF-1 site. We therefore conclude that the most essential transcription factor in the human RB gene is likely to be hGABP/E4TF1.

Prospective and randomized trial of lipiodol-transcatheter arterial chemoembolization for treatment of hepatocellular carcinoma: a comparison of epirubicin and doxorubicin (second cooperative study). The Cooperative Study Group for Liver Cancer Treatment of Japan

A randomized, controlled clinical trial was conducted to compare the use of epirubicin (EPI) and doxorubicin (DOX) in Lipiodol (Laboratoire Guerbet, Roissy-Charles-de-Gaulle Cedex, France)-transcatheter arterial chemoembolization as a treatment of hepatocellular carcinoma. One hundred ninety-two hospitals participated, and 415 patients were enrolled in the study during the period between October 1989 and December 1990. The patients were randomly allocated to group A (EPI) or group B (DOX) by a centralized telephone registration. The actual doses of EPI and DOX were 72 mg/body and 48 mg/body, respectively. The 1-, 2-, and 3-year survival rates were, respectively, 69%, 44%, and 33% for group A and 73%, 54%, and 37% for group B. There were no statistically significant differences (P = .2296, log-rank test). When each group of patients was classified retrospectively into high-risk and low-risk subgroups based on the severity index calculated by the Cox regression model from the significant prognostic factors (the pretreatment tumor size, the pretreatment serum alpha-fetoprotein level, tumor encroachment, and Child's classification), the survival curve of the low-risk DOX subgroup was significantly superior to that of the low-risk EPI subgroup (P = .0182). However, there was no significant difference between the high-risk subgroups (P = .4606). The change in the serum alpha-fetoprotein level, the extent of Lipiodol accumulation in the tumor, and the extent of tumor reduction after the treatment did not show any significant differences between the groups. The white blood cell count in group B showed a tendency to decrease slightly more than in group A at 3 weeks after Lipiodol-transcatheter arterial chemoembolization. In conclusion, there was no statistically significant difference between the survival curves of the EPI and DOX groups in Lipiodol-transcatheter arterial embolization treatment of hepatocellular carcinoma.

[Lipoprotein(a) as a risk factor for cardiovascular disease in elderly patients with diabetes]

Lipoprotein(a) (Lp(a)) is an independent risk factor for cardiovascular diseases in non-diabetic people, but few studies have been done in diabetic patients. To investigate whether Lp(a) is a risk factor for cardiovascular disease in elderly people with diabetes, we examined the association of Lp(a) and serum lipid levels (total cholesterol: TC; triglycerides: TG; and high-density lipoprotein cholesterol: HDL-c) with the incidence of coronary artery disease and cerebrovascular disease. We studied 354 outpatients(131 men and 223 women, 60-97 years of age) with non-insulin-dependent diabetes mellitus. The mean concentration of Lp(a) was 21.1 +/- 19.6 mg/dl and the median was 14.0 mg/dl. The Lp(a) concentration did not correlate significantly with age or with sex, but it did correlate significantly with TC (r = 0.152, p < 0.05) and with the level of apoprotein B (r = 0.168, p < 0.05). The incidence of cerebrovascular disease was significantly higher in patients with high concentrations of Lp(a) (> or = 30 mg/ dl) than in those with low concentrations (< 30 mg/ dl). Multivariate logistic regression analysis revealed that male sex, hypertension, a high level of HbA1c, a low level of HDL, and a high level of Lp(a) were independent risk factors for cerebrovascular disease. The incidence of coronary artery disease tended to the higher in those with high concentrations of Lp(a) (> or = 30 mg/dl). However, multivariate logistic regression analysis revealed no significant correlation between Lp(a) concentration and the incidence of coronary artery disease. We conclude that a high concentration of Lp(a) is an independent risk factor for cerebrovascular disease in elderly patients with diabetes.

[The TRAF family protein-mediated B cell proliferation signal and the mechanism of LMP1-induced B cell transformation]

We have demonstrated that CD40 signallings induce Bcl-xL, Cdk4 and 6 expression and suppress p27kip-1 expression to block apoptosis and induce B cell proliferation. We have also identified putative signal transducers of CD40, designated TRAF5 and TRAF6, in addition to TRAF1, 2 and 3 demonstrated by others. The EBV transforming protein LMP1 binds to TRAF proteins through the cytoplasmic region required for B cell transformation. Thus, LMP1 appears to be a constitutively activated CD40 receptor on the basis of an ability to aggregate in the plasma membrane and its association with TRAF proteins. However, regulation of the Bcl-xL, Cdk4 and 6 and p27kip-1 expression by LMP1 and the molecular mechanism of LMP1-mediated B cell transformation remain to be elucidated.