Ammonia: a possible promotor in Helicobacter pylori-related gastric carcinogenesis.

Helicobacter pylori (HP) has been shown to possibly be a pathogen of gastric carcinoma. HP has urease activity and produces ammonia in the stomach. In this study, the role of ammonia on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated in rats. After 24 weeks pretreatment with MNNG (83 mg/l), 0.01% ammonia or tap water as a drinking water was administered for 24 weeks. The ammonia-treated rats showed a significantly higher incidence of gastric cancer (percent of animals with tumors and number of tumors per rat). Ammonia would thus appear to have an important role in HP-related human gastric carcinogenesis.     

INTRA- AND INTERINDIVIDUAL VARIATION IN THE PHARMACOKINETICS OF TACROLIMUS (FK506) IN KIDNEY TRANSPLANT RECIPIENTS—IMPORTANCE OF TROUGH LEVEL AS A PRACTICAL INDICATOR

Background: Tacrolimus (FK506) is currently used as the primary immunosuppressant in clinical kidney transplantation in some centers. The purpose of this study was to evaluate the pharmacokinetics of this drug and to see if trough level, which has been used widely in therapeutic drug monitoring, can be used as an appropriate substitute for other pharmacokinetic measurement tests. Methods: The blood concentration-time curve was studied in 10 kidney transplant recipients on 26 Occasions after oral dosage of 2 to 18 mg every 12 hours. Whole blood concentration was measured by two-step irnmunoabsorption assay. Methylprednisolone was used as a concomitant immuno-suppressive drug. Results: The blood concentration-time curves showed remarkable interindividual variation. lntraindividual variation was also found, but the degree of variation was slight compared with interindividual variation. On 17 occasions of measurement in one patient, the dose was significantly correlated with trough (r = 0.684). C_max (r = 0.838) and AUC_0–12 (r = 0.817). In nine patients on nine occasions, however, the dose was not significantly correlated with trough (r = 0.351), C_max (r = 0.270) or AUC_0–12 (r = 0.355). t_max ranged from one to four hours (mean + SD; 2.8 + 1.3) and fluctuated in both intra- and interindividual measurements. In spite of a wide variation in the blood concentration-time-curve patterns, a highly significant linear relationship between trough and C_max or AUC_0–12 was observed in both intraindividual (C_max, r = 0.876; AUC_0–12, r = 0.926) and interindividual (C_max, f = 0.943; AUC_0–12, r = 984) measurements. Concluslons: We conclude that trough level is a practical acceptable indicator of the blood levels of tacrolimus, and can be used to monitor blood concentration.     

No difference in serum leptin concentrations between urban-dwelling Austronesians and Non-Austronesians in Papua New Guinea.

Pacific Islands populations can be broadly divided into Austronesians (AN) and Non-Austronesians (NAN); obesity and type 2 diabetes are prevalent in the former, although leptin levels in both groups have seldom been investigated. Thirty-seven (20 male and 17 female) adult pairs, matched by age and percent body fat, from AN-speaking Balopa and NAN-speaking Huli, all of whom migrated to settle in Port Moresby, the capital of Papua New Guinea, were selected for comparison of their serum leptin concentrations. The Balopa did not differ significantly from the Huli in age (30.5 +/- 9.7 and 30.0 +/- 8.7 years for males, 33.7 +/- 8.9 and 34.1 +/- 7.5 years for females, respectively) or percent body fat (19.4 +/- 5.6 and 18.8 +/- 4.6 for males, 34.1 +/- 6.2 and 33.3 +/- 5.0 for females), although the BMI of females was lower in the Balopa (26.4 +/- 4.9) than in the Huli (29.7 +/- 4.7) (P = 0.02). In both ethnic groups, females had markedly higher leptin concentrations than males, but there was no significant inter-group difference in males (3.5 +/- 2.6 and 3.1 +/- 4.7 ng/ml, P = 0.14) or females (22.7 +/- 12.9 and 19.7 +/- 11.9 ng/ml, P = 0.40), after controlling for lifestyle factors and serum lipids. Multiple regression analysis revealed that significant predictors of leptin concentration were % body fat (beta = 0.58), sex (male, 0; female, 1; beta = 0.27), and smoker status (non-smoker, 0; smoker, 1; beta = -0.15) (R(2) = 0.80), implying that the leptin concentration was primarily determined by lifestyle-derived body fatness. In conclusion, the NAN populations do not endogenously differ in leptin status from the AN populations, who have been recognized as a typical group with a "thrifty" genotype.     

Mutational screening of APP gene in patients with early-onset Alzheimer disease utilizing mismatched PCR-RFLP

To elucidate the frequency of mutations of the β/A4 amyloid protein precursor (APP) gene in early-onset Alzheimer disease, we designed a mismatched PCR-RFLP that can identify all kinds of missense mutations at codon 717 in addition to the seven kinds of known mutations at exon 17. When we screened mutations at exon 17 utilizing this method and the double missense mutations at exon 16 of the APP gene by PCR-RFLP, no cases revealed mutations of the APP gene among 13 familial and 54 sporadic cases, except one family (OS-1) that had previously been reported and used as a positive control of APP717(Val → Ile). Our results support the hypothesis that mutations in the APP gene are not major causes in early-onset Alzheimer disease.     

Reduction of a vascular endothelial growth factor receptor, fetal liver kinase-1, by antisense oligonucleotides induces motor neuron death in rat spinal cord exposed to hypoxia

Vascular endothelial growth factor (VEGF) is reported to play a neuroprotective role through a VEGF receptor, fetal liver kinase-1 (Flk-1) in vitro. We investigated whether reduction of Flk-1 could induce motor neuron loss in rat spinal cord by inhibiting the expression of Flk-1 in rat spinal cord using antisense oligodeoxynucleotides (ODNs) against the Flk-1 receptor. Rat spinal cord was repetitively exposed to 12% hypoxia, and the change of the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway and the mitogen-activated protein kinase kinase (MEK)/extracellular-signal-regulated kinase (ERK) pathway was examined. Intrathecal infusion of Flk-1 antisense ODNs for 7 days suppressed almost completely Flk-1 expression in the lumbar segment of the spinal cord and was followed by a hypoxic challenge with 12% oxygen for 1 h that was repeated for 7 more days. In the lumbar segment, we observed that reduced Flk-1 expression and hypoxic challenge for 7 days resulted in approximately 50% loss of motor neurons, in which the activation of Akt and ERK, that is, increased levels of phosphorylated-Akt and of phosphorylated-ERK by hypoxia, was markedly inhibited. In contrast, the reduction of Flk-1 expression alone did not induce motor neuron loss. These results suggest that VEGF exerts its protective effect on motor neurons against hypoxia-induced toxicity by the Flk-1 receptor through the PI3-K/Akt and the MEK/ERK signaling pathways.     

Lowe syndrome protein Ocrl1 is translocated to membrane ruffles upon Rac GTPase activation: a new perspective on Lowe syndrome pathophysiology

Oculocerebrorenal Lowe syndrome is a rare X-linked disorder characterized by bilateral cataract, mental retardation and renal Fanconi syndrome. The Lowe syndrome protein Ocrl1 is a PIP2 5-phosphatase, primarily localized to the trans-Golgi network (TGN), which 'loss of function' mutations result in PIP2 accumulation in patient's cells. Although PIP2 is involved in many cell functions including signalling, vesicle trafficking and actin polymerization, it has been difficult so far to decipher molecular/cellular mechanisms responsible for Lowe syndrome phenotype. We have recently shown that, through its C-terminal RhoGAP domain, Ocrl1 forms a stable complex with Rac GTPase within the cell. In line with this finding, we report here that upon epidermal growth factor induced Rac activation in COS-7 cells, a fraction of Ocrl1 translocates from TGN to plasma membrane and concentrates in membrane ruffles. In order to investigate the functionality of Ocrl1 in plasma membrane, we have analysed PIP2 distribution in human dermal fibroblasts (HDFs) from Lowe patients versus control HDFs. As revealed by both immunodetection and green fluorescent protein-PH binding, PIP2 was found strikingly to accumulate in PDGF induced ruffles in Lowe HDFs when compared with control. This suggests that Ocrl1 is active as a PIP2 5-phosphatase in Rac induced membrane ruffles. Cellular properties such as cell migration and establishment of cell-cell contacts, which depend on ruffling and lamellipodia formation, should be further investigated to understand the pathophysiology of Lowe syndrome.     

VEGF、ANG-1、ANG-2、TSP-1的表达与胆管细胞性肝癌血管生成和侵润转移的关系

目的：研究血管内皮生长因子（VEGF）、血管生成素-1（ANG-1）、血管生成素-2（ANG-2）、血小板反应蛋白-1（TSP-1）的表达与胆管细胞性肝癌(CCC)血管生成和侵润转移的关系。方法： 对33例手术切除的CCC标本进行CD34、VEGF、 ANG-1、 ANG-2 和TSP-1的免疫组化染色，研究VEGF、ANG-1、ANG-2、TSP-1的表达与胆管细胞性肝癌血管生成和肿瘤门静脉侵犯、肝内转移、淋巴结转移以及肿瘤分化水平之间的关系。 结果： 本组CCC的微血管密度（MVD）为(87.2±52.6)/mm2，VEGF、ANG-1、ANG-2 和TSP-1的阳性率分别为75.6%、36.0%、57.6%和45.5%。VEGF和ANG-2的阳性表达与高MVD相关，TSP-1则与MVD负相关（P<0.01,P<0.05,P<0.01）。阳性TSP-1与肝内转移正相关（46.7% vs 5.6%，P<0.05）。结论： CCC瘤内的血管新生活跃，VEGF和ANG-2的阳性表达与CCC血管生成正相关，TSP-1则与其负相关，TSP-1的阳性表达还与肝内转移相关，VEGF、ANG-1、ANG-2的表达与肿瘤的侵润转移未见显著相关。     

Ultrastructural myeloperoxidase activity and expression of myeloid-associated antigens in acute lymphoblastic leukemia

Ultrastructural myeloperoxidase (MPO) activity and myeloid-associated antigen (MyAg) expression were investigated in 12 adult patients with acute lymphoblastic leukemia (ALL). Ultrastructural MPO was detected by 3 different methods. Immunophenotyping was performed by flow cytometry, using a series of monoclonal antibodies. Ultrastructural MPO-positive blast cells were detected in 6 patients (50%). In 5 of these 6 patients, the methods detecting both MPO and platelet peroxidase (PPO) activities found MPO-positive blast cells more frequently than those detecting MPO activity alone. In 2 patients (17%), at least one kind of MyAg was positive. Ultrastructural MPO activity was detected more frequently than MyAg expression in ALL patients. This method of detecting PPO and MPO is recommended for detection of ultrastructural MPO-positive ALL.     

α2-Macroglobulin secretion enhanced in rat hepatocytes by partially characterized factor from Kupffer cells

Isolated rat Kupffer cells produced a factor which stimulated the synthesis of ₂-macroglobulin (2M) in primary cultured rat hepatocytes. Although Kupffer cells placed in culture produced the factor without stimulation by lipopolysaccharide (LPS), the LPS-stimulated cells produced larger amounts of the factor. On the other hand, the production of the factor was inhibited by addition of actinomycin D. The induction of2M synthesis by cultured hepatocytes was enhanced in the presence of dexamethasone (Dex), in that hepatic synthesis of2M increased by addition of the factor alone and with Dex 1.5 and three- to four-fold, respectively. The factor was nondialyzable and stable at 60°C for 30 min. When the factor was fractionated using the molecular sieve method, the activity recovered in the fraction had a molecular weight of over 30,000.     

Precursor genes of future pandemic influenza viruses are perpetuated in ducks nesting in Siberia

Summary.  Influenza A viruses of different subtypes were isolated from fecal samples of ducks in their nesting areas in Siberia in summer from 1996 to 1998. Phylogenetic analysis of the NP genes of the isolates in Siberia and those in Hokkaido, Japan on their flyway of migration from Siberia to the south in autumn revealed that they belong to the Eurasian lineage of avian influenza viruses. It is noted that the genes of the isolates in Siberia are closely related to those of H5N1 influenza virus strains isolated from chickens and humans in Hong Kong in 1997 as well as to those of isolates from domestic birds in southern China. The results indicate that influenza viruses perpetuated in ducks nesting in Siberia should have contributed genes in the emergence of the H5N1 virusin Hong Kong. Vaccine prepared from avirulent A/duck/Hokkaido/4/96 (H5N3) influenza virus was potent enough to protect mice from challenge with lethal dose of the pathogenic H5N1 virus [19]. Intensive surveillance study of aquatic birds especially in Siberia is, therefore, stressed to provide information on the future pandemic influenza virus strains and for vaccine preparation. Received August 24, 1999/Accepted January 7, 2000