Advanced glycation end-products: a review

Advanced glycation end-products are a complex and heterogeneous group of compounds that have been implicated in diabetes related complications. At present it is not known if they are the cause or the consequence of the complications observed. We discuss the chemistry of advanced glycated end-product formation and their patho-biochemistry particularly in relation to the diabetic microvascular complications of retinopathy, neuropathy and nephropathy as well as their role in the accelerated vasculopathy observed in diabetes. The concept of carbonyl stress as a cause for advanced glycated end-product toxicity is mentioned. We discuss alterations in the concentrations of advanced glycated end-products in the body, particularly in relation to changes occurring with age, diabetes and its complications such as nephropathy. Problems relating to current methods of advanced glycated end-product detection and measurement are highlighted including the lack of a universally established method of detection or unit of measurement. Agents used for the treatment of advanced glycated end-product accumulation are reviewed, with an emphasis on the results of the recent phase III trials using aminoguanidine and diabetes related complications.

p53AIP1, a potential mediator of p53-dependent apoptosis, and its regulation by Ser-46-phosphorylated p53

Through direct cloning of p53 binding sequences from human genomic DNA, we have isolated a novel gene, designated p53AIP1 (p53-regulated Apoptosis-Inducing Protein 1), whose expression is inducible by wild-type p53. Ectopically expressed p53AIP1, which is localized within mitochondria, leads to apoptotic cell death through dissipation of mitochondrial A(psi)m. We have found that upon severe DNA damage, Ser-46 on p53 is phosphorylated and apoptosis is induced. In addition, substitution of Ser-46 inhibits the ability of p53 to induce apoptosis and selectively blocks expression of p53AIP1. Our results suggest that p53AIP1 is likely to play an important role in mediating p53-dependent apoptosis, and phosphorylation of Ser-46 regulates the transcriptional activation of this apoptosis-inducing gene.

Nonadipose tissue production of leptin: leptin as a novel placenta-derived hormone in humans

Leptin is a circulating hormone that is expressed abundantly and specifically in the adipose tissue. It is involved in the regulation of energy homeostasis, as well as the neuroendocrine and reproductive systems. Here, we demonstrate production of leptin by nonadipose tissue, namely, placental trophoblasts and amnion cells from uteri of pregnant women. We show that pregnant women secrete a considerable amount of leptin from the placenta into the maternal circulation as compared with nonpregnant obese women. Leptin production was also detected in a cultured human choriocarcinoma cell line, BeWo cells, and was augmented during the course of forskolin-induced differentiation of cytotrophoblasts into syncytiotrophoblasts. Plasma leptin levels were markedly elevated in patients with hydatidiform mole or choriocarcinoma and were reduced after surgical treatment or chemotherapy. Leptin is also produced by primary cultured human amnion cells and is secreted into the amniotic fluid. The present study provides evidence for leptin as a novel placenta-derived hormone in humans and suggests the physiologic and pathophysiologic significance of leptin in normal pregnancy and gestational trophoblastic neoplasms.

Somatic mutations of the APC gene in colorectal tumors: mutation cluster region in the APC gene

We examined somatic mutations of the adenomatous polyposis coli (APC) gene in 63 colorectal tumors (16 adenomas and 47 carcinomas) developed in familial adenomatous polyposis (FAP) and non-FAP patients. In addition to loss of heterozygosity (LOH) at the APC locus in 30 tumors, 43 other somatic mutations were detected. Twenty-one of them were point mutations; 16 nonsense and two missense mutations, and three occurred in introns at the splicing site. Twenty-two tumors had frameshift mutations due to deletion or insertion; nineteen of them were deletions of one to 31 bp and three were a 1-bp insertion. One tumor had a 1-bp deletion in an intron near the splicing site. Hence, 41 (95%) of 43 mutations resulted in truncation of the APC protein. Over 60% of the somatic mutations in the APC gene were clustered within a small region of exon 15, designated as MCR (mutation cluster region), which accounted for less than 10% of the coding region. Combining these data and the results of LOH, more than 80% of tumors (14 adenomas and 39 carcinomas) had at least one mutation in the APC gene, of which more than 60% (9 adenomas and 23 carcinomas) had two mutations. These results strongly suggest that somatic mutations of the APC gene are associated with development of a great majority of colorectal tumors.

Topical formulations and wound healing applications of chitosan

Chitosan is being used as a wound-healing accelerator in veterinary medicine. To our knowledge, chitosan enhances the functions of inflammatory cells such as polymorphonuclear leukocytes (PMN) (phagocytosis, production of osteopontin and leukotriene B4), macrophages (phagocytosis, production of interleukin (IL)-1, transforming growth factor beta 1 and platelet derived growth factor), and fibroblasts (production of IL-8). As a result, chitosan promotes granulation and organization, therefore chitosan is beneficial for the large open wounds of animals. However, there are some reported complications of chitosan application. Firstly, chitosan causes lethal pneumonia in dogs which are given a high dose of chitosan. In spite of application of chitosan to various species, this finding is observed only in dogs. Secondly, intratumor injection of chitosan on mice bearing tumor increases the rate of metastasis and tumor growth. Therefore, it is important to consider these effects of chitosan, prior to drug delivery.

Discovery of cyanovirin-N, a novel human immunodeficiency virus-inactivating protein that binds viral surface envelope glycoprotein gp120: potential applications to microbicide development

We have isolated and sequenced a novel 11-kDa virucidal protein, named cyanovirin-N (CV-N), from cultures of the cyanobacterium (blue-green alga) Nostoc ellipsosporum. We also have produced CV-N recombinantly by expression of a corresponding DNA sequence in Escherichia coli. Low nanomolar concentrations of either natural or recombinant CV-N irreversibly inactivate diverse laboratory strains and primary isolates of human immunodeficiency virus (HIV) type 1 as well as strains of HIV type 2 and simian immunodeficiency virus. In addition, CV-N aborts cell-to-cell fusion and transmission of HIV-1 infection. Continuous, 2-day exposures of uninfected CEM-SS cells or peripheral blood lymphocytes to high concentrations (e.g., 9,000 nM) of CV-N were not lethal to these representative host cell types. The antiviral activity of CV-N is due, at least in part, to unique, high-affinity interactions of CV-N with the viral surface envelope glycoprotein gp120. The biological activity of CV-N is highly resistant to physicochemical denaturation, further enhancing its potential as an anti-HIV microbicide.

Plasma (1-->3)-beta-D-glucan measurement in diagnosis of invasive deep mycosis and fungal febrile episodes

(1-->3)-beta-D-glucan is a characteristic fungal cell-wall constituent. To assess the clinical usefulness of this glucan in screening for invasive fungal infection or fungal febrile episodes, we measured the plasma concentration at the time of routine blood culture in 202 febrile episodes by means of factor G, a horseshoe-crab coagulation enzyme that is extremely sensitive to this polysaccharide. With a plasma cut-off value of 20 pg/mL, 37 of 41 episodes of definite fungal infections (confirmed at necropsy or by microbiology) had positive results (sensitivity 90%). All of 59 episodes of non-fungal infections, tumour fever, or collagen diseases had concentrations below the cut-off value (specificity 100%). Of 102 episodes of fever of unknown origin, 26 had plasma glucan concentrations of more than 20 pg/mL. With those 102 cases taken as non-fungal infections, the positive predictive value of the test was estimated as 59% (37/63), the negative predictive value as 97% (135/139), and the efficiency as 85% (172/202). The positive predictive value should improve if there were a sensitive gold standard that could discriminate fungal from non-fungal infections. Causative fungi included candida, aspergillus, cryptococcus, and trichosporon. Determination of plasma (1-->3)-beta-D-glucan with factor G is a highly sensitive and specific test for invasive deep mycosis and fungal febrile episodes, and will substantially benefit immunocompromised patients.

Role and interaction of connective tissue growth factor with transforming growth factor-beta in persistent fibrosis: A mouse fibrosis model

Skin fibrotic disorders are understood to develop under the influence of some growth factors, such as transforming growth factor-beta (TGF-beta), basic fibroblast growth factor (bFGF), or connective tissue growth factor (CTGF). To establish an appropriate animal model of skin fibrosis by exogenous application of growth factors, we investigated the in vivo effects of growth factors by injecting TGF-beta, CTGF, and bFGF into the subcutaneous tissue of newborn mice. A single application of TGF-beta or bFGF resulted in the formation of transient granulated tissue that disappeared despite 7 days of consecutive injections. A single CTGF injection also caused slight granulation. However, injecting TGF-beta plus CTGF produced long-term fibrotic tissue, which persisted for at least 14 days. Also, fibrotic tissue was observed when CTGF was injected from 4 to 7 days after TGF-beta injections for the first 1-3 days. In situ hybridization analysis revealed the expression of CTGF mRNA in the fibroblasts at least in a few fibrotic conditions. These findings suggest that either CTGF mRNA or an application of exogenous CTGF protein is required for the development of persistent fibrosis. From our study, it appears that interaction of several growth factors is required for persistent fibrotic tissue formation, with TGF-beta causing the induction and CTGF needed for maintenance of skin fibrosis. The animal model on skin fibrosis by exogenous application of growth factors developed in this study may prove useful for future studies on fibrotic disorders.

Germ-line mutations of the APC gene in 53 familial adenomatous polyposis patients

We searched for germ-line mutations of the APC gene in 79 unrelated patients with familial adenomatous polyposis using a ribonuclease protection analysis coupled with polymerase chain reaction amplifications of genomic DNA. Mutations were found in 53 patients (67%); 28 of the mutations were small deletions and 2 were 1- to 2-base-pair insertions; 19 were point mutations resulting in stop codons and only 4 were missense point mutations. Thus, 92% of the mutations were predicted to result in truncations of the APC protein. More than two-thirds (68%) of the mutations were clustered in the 5' half of the last exon, and nearly two-fifths of the total mutations occurred at one of five positions. This information has significant implications for understanding the role of APC mutation in inherited forms of colorectal neoplasia and for designing effective methods for genetic counseling and presymptomatic diagnosis.

International Conference for the Development of a Consensus on the Management and Prevention of Severe Candidal Infections

Because of the rapidly increasing incidence of serious candidal infections, a consensus conference of 22 investigators from the United States, Europe, and Japan was held to discuss strategies for the prevention and treatment of deep-organ infections caused by Candida species. Commonly asked questions concerning the management of candidal infections were selected for discussion by the participating investigators. Possible answers to the questions were developed by the investigators, who then voted anonymously for their preferences. In certain instances, unanimity or a strong consensus was the result. In all cases, the full spectrum of responses was recorded and is presented in this report. The forms of candidal infection addressed included candidemia, candiduria, hepatosplenic candidiasis (chronic systemic candidiasis), candidal endophthalmitis, and candidal peritonitis. Prevention and treatment strategies were considered for patients who have undergone surgery, for neutropenic and nonneutropenic patients, and for patients who have undergone bone marrow and solid organ transplantation. The therapeutic roles of amphotericin B (standard and lipid formulations) and the azoles were considered.

Simultaneous establishment of monoclonal antibodies specific for either cyclobutane pyrimidine dimer or (6-4)photoproduct from the same mouse immunized with ultraviolet-irradiated DNA

Six new monoclonal antibodies (TDM-2, TDM-3, 64M-2, 64M-3, 64M-4 and 64M-5) specific for ultraviolet (UV) induced DNA damage have been established. In the antibody characterization experiments, two TDM antibodies were found to show a dose-dependent binding to UV-irradiated DNA (UV-DNA), decrease of binding to UV-DNA after cyclobutane pyrimidine dimer photoreactivation, binding to DNA containing cyclobutane thymine dimers, and unchanged binding to UV-DNA after photoisomerization of (6-4)photoproducts to Dewar photoproducts. These results indicated that the epitope of TDM monoclonal antibodies was the cyclobutane pyrimidine dimer in DNA. On the other hand, four 64M antibodies were found to show a dose-dependent binding to UV-DNA, unchanged binding to UV-DNA after cyclobutane pyrimidine dimer photoreactivation, undetectable binding to DNA containing thymine dimers, and decrease of binding to UV-DNA after photoisomerization of (6-4)photoproducts. These results indicated that the epitope of 64M antibodies was the (6-4)photoproduct in DNA. This is the first report of the simultaneous establishment of monoclonal antibodies against the two different types of photolesions from the same mouse. By using these monoclonal antibodies, we have succeeded in measuring both cyclobutane pyrimidine dimers and (6-4)photoproducts in the DNA from human primary cells irradiated with physiological UV doses.

Irradiation synchronized with respiration gate

A respiratory gating technique was developed for radiotherapy of tumors unable to remain stable due to respiration. Irradiation was started and stopped with a microwave oscillator of a linear accelerator controlled by gating signals at specific points in the respiratory cycle. This technique was tested in a phantom specially designed to simulate a patient with lung cancer and in clinical therapy for lung tumors of seven patients. A mask was used to check ventilation in the phantom and airbags were used to measure thoracoabdominal pressure in patients and in the phantom; this enabled us to detect the excursion of the tumors. Low sensitivity film for verification demonstrated the efficacy of this technique. The gated irradiation was proved to ensure more precise radiotherapy for tumors located close to the diaphragm.

Predictive factors for malignancy in intraductal papillary-mucinous tumours of the pancreas

BACKGROUND

Preoperative assessment of the likelihood of malignancy in intraductal papillary-mucinous tumour (IPMT) of the pancreas is often difficult. Predictive factors for malignancy and invasive carcinoma in IPMT were analysed.

METHODS

Sixty-two patients with IPMT underwent surgical treatment, with histological confirmation of adenoma in 28, carcinoma in situ in 14 and invasive carcinoma in 20. Tumours were of the main duct type in 14 patients, branch duct type in 32, and combined type in 16. A multivariate analysis of 17 potential predictive factors, including preoperative clinical and imaging findings, was conducted.

RESULTS

Multivariate analysis identified two independent predictive factors for malignancy: mural nodules and main pancreatic duct diameter of 7 mm or more. Mural nodules in the main duct or combined type, and mural nodules and tumour diameter of 30 mm or more in the branch duct type were particularly indicative of malignancy. Mural nodules, jaundice and main duct or combined type were predictors of invasive carcinoma in the multivariate analysis.

CONCLUSION

The above factors should be considered in the diagnosis of IPMT to facilitate appropriate management.

A human gene responsible for Zellweger syndrome that affects peroxisome assembly

The primary defect arising from Zellweger syndrome appears to be linked to impaired assembly of peroxisomes. A human complementary DNA has been cloned that complements the disease's symptoms (including defective peroxisome assembly) in fibroblasts from a patient with Zellweger syndrome. The cause of the syndrome in this patient was a point mutation that resulted in the premature termination of peroxisome assembly factor-1. The homozygous patient apparently inherited the mutation from her parents, each of whom was heterozygous for that mutation.

Higher frequency of Smad4 gene mutation in human colorectal cancer with distant metastasis

We have previously detected an increased frequency of loss of heterozygosity (LOH) on chromosome 18q during progression of colorectal carcinomas. To clarify the target of 18qLOH, mutation of Smad4 and Smad2 genes was analysed in 176 colorectal tumors with different stages, including liver metastasis, from 111 sporadic, 52 familial adenomatous polyposis (FAP) and nine hereditary nonpolyposis colorectal cancer (HNPCC) patients. Mutation of other Smad gene families in the TGF-beta signaling pathway was also examined. Twenty-one Smad4 mutations and one Smad2 mutation were detected, whereas mutation of Smad3, 6 and 7 genes was not detected. Smad4 mutations included seven frameshift, one inframe deletion, four nonsense and nine missense mutations, 95% of which resulted in alteration of Smad4 protein regions included in homo-oligomer and hetero-oligomer formation. Frequencies of tumors with Smad4 mutation were 0/40 (0%) in adenoma, 4/39 (10%) in intramucosal carcinoma, 3/44 (7%) in primary invasive carcinoma without distant metastasis, 6/17 (35%) in primary invasive carcinoma with distant metastasis, and 11/36 (31%) in distant metastasis (metastatic/non-metastatic: P=0.006 approximately 0.01). Loss of the other allele was observed in 19 of 20 (95%) invasive and metastasized carcinomas with Smad4 mutations. In four cases both primary and metastasized carcinomas in the same patients showed the same mutations. The present results suggest that Smad4 gene is one of true targets of 18qLOH, and that its inactivation is involved in advanced stages, such as distant metastasis, in human colorectal carcinogenesis.

Molecular nature of colon tumors in hereditary nonpolyposis colon cancer, familial polyposis, and sporadic colon cancer

BACKGROUND & AIMS

Microsatellite instability (replication error [RER]) is a characteristic of tumors in hereditary nonpolyposis colon cancer (HNPCC), but the mechanism of HNPCC carcinogenesis is not yet understood. To clarify the nature of HNPCC tumors, RER and genetic changes were compared between HNPCC and non-HNPCC tumors.

METHODS

RER and genetic changes were analyzed in 21 HNPCC, 389 familial adenomatous polyposis, and 206 sporadic tumors using polymerase chain reaction, single-strand conformation polymorphism, sequencing, and Southern hybridization. RESULTS. in HNPCC, 95% tumors at all stages showed RER positivity (altered loci, 4.3 of 5). In familial adenomatous polyposis and sporadic tumors, RER positivity (1.7 of 5) was 3% in adenoma and intramucosal carcinoma, 13%-24% in invasive carcinoma, and 35% in carcinoma metastasized to liver. Fifty percent of RER-positive HNPCC tumors had both germline and somatic mutations of hMSH2 or hMLH1 gene, whereas 6% of RER-positive non-HNPCC had somatic mutation. APC, p53, and K-ras-2 mutations and loss of heterozygosity of tumor-suppressor genes were significantly less frequent (P = 0.03 to 0.0006) but transforming growth factor beta type II receptor mutation was significantly more frequent (P = 0.000001) in HNPCC than in non-HNPCC.

CONCLUSIONS

RER positivity occurs from an early stage of carcinogenesis in HNPCC but in later stages in non-HNPCC. Most HNPCC tumors may develop through different genetic changes from those in the adenoma-carcinoma sequence, although a certain percentage develops through APC mutation.

Microglial activation resulting from CD40-CD40L interaction after beta-amyloid stimulation

Alzheimer's disease (AD) has a substantial inflammatory component, and activated microglia may play a central role in neuronal degeneration. CD40 expression was increased on cultured microglia treated with freshly solublized amyloid-beta (Abeta, 500 nanomolar) and on microglia from a transgenic murine model of AD (Tg APPsw). Increased tumor necrosis factor alpha production and induction of neuronal injury occurred when Abeta-stimulated microglia were treated with CD40 ligand (CD40L). Microglia from Tg APPsw mice deficient for CD40L demonstrated reduction in activation, suggesting that the CD40-CD40L interaction is necessary for Abeta-induced microglial activation. Finally, abnormal tau phosphorylation was reduced in Tg APPsw animals deficient for CD40L, suggesting that the CD40-CD40L interaction is an early event in AD pathogenesis.

Characterization of a novel aquaretic agent, OPC-31260, as an orally effective, nonpeptide vasopressin V2 receptor antagonist

1. OPC-31260, a benzazepine derivative, has been studied for its ability to antagonize the binding of arginine vasopressin (AVP) to receptors in rat liver (V1) and kidney (V2) plasma membranes, for antagonism of the antidiuretic action of AVP in alcohol-anaesthetized rats and for diuretic action in conscious normal rats. 2. OPC-31260 caused a competitive displacement of [3H]-AVP binding to both V1 and V2 receptors with IC50 values of 1.2 +/- 0.2 x 10(-6) M and 1.4 +/- 0.2 x 10(-8) M, respectively. 3. OPC-31260 at doses of 10 to 100 micrograms kg-1, i.v., inhibited the antidiuretic action of exogenously administered AVP in water-loaded, alcohol-anaesthetized rats in a dose-dependent manner. OPC-31260 did not exert an antidiuretic activity suggesting that it is not a partial V2 receptor agonist. 4. After oral administration at doses of 1 to 30 mg kg-1 in normal conscious rats, OPC-31260 dose-dependently increased urine flow and decreased urine osmolality. The diuretic action of OPC-31260 was characterized as aquaresis, the mode of diuretic action being different from previously known diuretic agents such as furosemide, hydrochlorothiazide and spironolactone. 5. The results indicate that OPC-31260 is a selective V2 receptor antagonist and behaves as an aquaretic agent. OPC-31260 will be a useful tool in studying the physiological role of AVP and in the treatment of various conditions characterized by water retention.

Expression of vascular endothelial growth factor (VEGF) in epithelial ovarian neoplasms: correlation with clinicopathology and patient survival, and analysis of serum VEGF levels

Vascular endothelial growth factor (VEGF) is known to be produced by various solid tumours and is thought to be involved in microvascular permeability and/or angiogenesis. To examine the relationship between VEGF expression in ovarian neoplasms and clinicopathological factors or patient survival, expression of VEGF was analysed immunohistochemically in 110 epithelial ovarian tumours. In addition, VEGF levels in the tumour fluid (17 patients), ascites (12 patients) and sera (38 patients) were determined using enzyme immunoassay. Positive immunostaining for VEGF was observed in 97% (68 out of 70) of ovarian carcinomas, which was significantly higher than that of tumours of low malignant potential (LMP) (13 out of 25; 52%) and benign cystadenomas (5 out of 15; 33%) (P < 0.01). In ovarian carcinomas, strong VEGF immunostaining was also observed more frequently in tumours of clear cell type (P < 0.05) in the advanced stage of disease (P < 0.05) and with positive peritoneal cytology (P < 0.01). Patients with strong VEGF staining had poorer survival rates than those with weak or no immunostaining for VEGF (P < 0.01). These findings suggest that strong VEGF expression plays an important role in the tumour progression of ovarian carcinoma. The enzyme immunoassay revealed higher serum VEGF levels in carcinoma patients than those in patients with LMP or benign tumours (P < 0.01). Serum VEGF levels decreased after the successful removal of tumours in ovarian cancer patients and, in one patient, the serum VEGF level was re-elevated during relapse. Therefore, serum VEGF could be used as a marker for monitoring the clinical course of ovarian cancer patients.

Increased generation of reactive oxygen species in embryos cultured in vitro

Previous studies have suggested that oxygen toxicity is closely related to the developmental blockage of embryos cultured in vitro. In this study, to obtain an actual proof of the increase in production of reactive oxygen species within embryos, we have measured the level of H2O2 in individual embryos using a fluorimetric method. Mouse (ICR) pronuclear stage embryos from the oviducts were cultured for a specified time under various conditions in a medium to which 2',7'-dichlorodihydrofluorescin diacetate was added. After washing the embryos, the fluorescence emissions of the H2O2-dependent oxidative product in embryos were measured. The fluorescent emissions were lowest in embryos cultured under 5% O2 and highest under 40% O2 (5% < 20% < 40%), just the inverse of the culture efficacy. The fluorescence emmissions of embryos cultured in Ham's F-10, which contains hypoxanthine and transition metals such as Cu and Fe, were higher than those cultured in BWW and alpha MEM, which do not contain these components (alpha MEM < BWW < Ham's F-10; again this is the inverse of the culture efficacy). The fluorescence emissions of embryos increased with the time of the exposure to visible light. L-cysteine and thioredoxin, both of which have been shown to promote embryo development, decreased the fluorescence emissions of embryos. All of these results would provide direct evidence for the hypothesis that oxygen radicals are involved in the developmental blockage.