A form of circulating interleukin-6 receptor component soluble gp130 as a potential interleukin-6 inhibitor in inflammatory bowel disease

The presence and the role of soluble gp130, the soluble form of a component of the interleukin (IL)-6 receptor complex, were investigated in inflammatory bowel disease. The serum concentrations of soluble gp130 were increased in ulcerative colitis (active disease, median, 93.5 ng/ml; interquartile range, 26-125 ng/ml; inactive disease, 81 ng/ml, 24.8-137.3 ng/ml) and to a lesser extent in Crohn's disease (active disease, 66 ng/ml, 44.4-87.6 ng/ml; inactive disease, 63 ng/ml, 43.5-82.5 ng/ml) compared to normal controls (43 ng/ml, 27-59 ng/ml). Paired analysis of serum samples showed a decrease of IL-6 and soluble IL-6 receptor concentrations in both diseases and an increase of soluble gp130 concentrations, especially in ulcerative colitis, just after the resolution of disease exacerbation. Size fractionation of the serum revealed that a part of the IL-6 co-eluted with soluble gp130 and soluble IL-6 receptor. The IL-6-induced proliferation of murine B9 hybridoma was enhanced by recombinant soluble IL-6 receptor, whereas the proliferation was inhibited by recombinant soluble gp130. These results indicate that soluble gp130 may function as a natural inhibitor of the IL-6 actions in inflammatory bowel disease.

Requirement of water-flow for sustainable growth of Pocilloporid corals during high temperature periods

Reef-building corals are threatened worldwide by mass-scale coral bleaching episodes that are pronounced in high sea surface temperature (SST) conditions. Although water-flow has been suggested to be a mitigating factor for bleaching, long-term effects of flow-mediated bleaching suppression are as yet not fully understood. In order to investigate flow effects, we monitored the corals Pocillopora damicornis and Stylophora pistillata grown for 20 months in experimental outdoor flumes with the flow rates of 20 cms(-1) (flow) and <3 cms(-1) (still). Although bleaching was observed under high SST conditions, both species showed a shorter period or entirely no visible bleaching under the flow conditions. Better colony growth was found in the flow conditions whereas significant growth suppression and higher mortality were observed in still conditions. We conclude that water-flow is an essential environmental factor for the corals P. damicornis and S. pistillata, especially under high SST conditions.

Adenovirus-mediated gene delivery of interleukin-10, but not transforming growth factor beta, ameliorates the induction of Graves' hyperthyroidism in BALB/c mice

Interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) are well known anti-inflammatory cytokines. We have studied the effect of adenovirus-mediated IL-10 and TGF-beta gene delivery on the induction of Graves' hyperthyroidism in our mouse model that involves repeated injections of adenovirus expressing the thyrotropin receptor A subunit (AdTSHR). We first constructed adenoviruses encoding the two cytokines (AdIL10 and AdTGF(beta)) and confirmed expression by in vitro infection of COS cells. Susceptible BALB/c mice were injected twice with AdTSHR alone or together with AdIL10 or AdTGF(beta), and bled two weeks after the second immunization. Significantly elevated serum thyroxine levels were seen in 26% of mice immunized with AdTSHR and AdIL10 versus 61% with AdTSHR alone. Levels of thyroid stimulating antibody, but not nonstimulating antibody, were also decreased, and TSHR-specific splenocyte secretion of interferon-gamma in recall assays was impaired in mice treated with AdIL10. In contrast, AdTGF(beta) had little effect on hyperthyroidism. Overall, our findings demonstrate that gene delivery of IL-10, but not TGF-beta, suppresses the induction of Graves' hyperthyroidism in a mouse model. However, the effect of IL-10 is less powerful than we observed previously with T helper type 2-inducers including adenovirus expressing IL-4, Shistosoma mansoni infection or alpha-galactosylceramide.

Evaluation of clinical and serological data from Taenia solium cysticercosis patients in eastern Inner Mongolia Autonomous Region, China

Neurocysticercosis (NCC) is one of the major causes of neurological disease in China. ELISA and immunoblotting using glycoproteins purified by preparative isoelectric focusing were used to detect human cysticercosis in Tongliao area, Inner Mongolia, China in 1998. Approximately 89% (39 of 44 inpatients and outpatients with suspected NCC at Tongliao City Hospital) were residents of Inner Mongolia. About 53% were male and 77% were of working age (18-59 years), and 32% were farmers. Immunoblotting and ELISA showed a high correlation. Of the 44 patients, 31 positive by cerebral computed tomography (CT) scan were confirmed serologically to have cysticercosis. In the ELISA, patients with no lesions by CT scan had lower OD values, similar to those of normal serum. These findings confirm that both ELISA and immunoblotting assays are sufficiently sensitive to detect asymptomatic or symptomatic cysticercosis patients.

CA-125 in menstrual discharge in patients with chronic pelvic pain

CA-125 levels in menstrual discharge were determined in 55 patients with chronic pelvic pain to evaluate whether this test would be useful in differentiating between pelvic pain due to endometriosis and other causes. Of the 28 women with endometriosis, 25 (89%) had CA-125 concentration greater than or equal to 72,000 units/ml. The frequencies of elevated levels in Stage I, Stage II and Stages III/IV were 85.7, 85.7 and 92.8%, respectively. When used for the detection of endometriosis, the test had a sensitivity of 89.3% and a specificity of 96.3%. These results suggest that CA-125 in menstrual discharge may be helpful in the evaluation of women with chronic pelvic pain.

Recent advances in basic and applied science for the control of taeniasis/cysticercosis in Asia

Detection of seven specific bands by immunoblot (IB) using glycoproteins (GPs) purified by lentil-lectin affinity chromatography has been the gold-standard for neurocysticercosis (NCC) serodiagnosis since 1989. However, due to the presence of contaminants, it was impossible to apply the GPs to ELISA. Our group at Asahikawa Medical College (AMC) succeeded in purifying the GPs by preparative isoelectric focusing; these higher quality GPs were suitable for ELISA. Based on the results of both IB and ELISA testing, developed at AMC for a field survey in Irian Jaya, it became evident that that area had pandemic NCC. We found many NCC patients, pigs full of cysts, and one dog infected with two cysts: these findings were based on serology. Recently, we conducted another survey to detect of the worm carriers of T. solium. Three of the 38 local people were positive by copro-antigen specific to Taenia species; these three patients expelled segments of Taenia spp and these were confirmed as those of T. solium by mitochondrial DNA analysis. When viable eggs of any taeniid species could be obtained, they can be developed into metacestodes in NOD-scid mice; it then becomes possible to analyze morphological dynamics, metacestode antigenicity, the efficacy of new metacestocidal drugs, and mitochondrial DNA. Mitochondrial DNA analysis of the specimens obtained in Irian Jaya was compared with that of other isolates worldwide. T. solium is now divided into two genotypes: the Asian type, and the Africa-American type. Some aspects of the pathological differences between the Asian and Africa-American types and the antigenic components of these two types are discussed.

Enhanced insulin gene expression by reduced intracellular glutathione level in insulin secreting cells MIN6

Glutathione (GSH) participates in deoxidization and elimination of hydrogen peroxide and other reactive oxygen species, and plays an important part in the antioxidant system. To investigate the effect of GSH content on insulin gene expression, we utilized a stable transfectant, designated as ribo-MIN6 cells, which were stably transfected with the ribozyme of gamma-glutamylcysteine synthetase (gamma-GCS), exhibiting approximately 50% reduction of intracellular GSH content. We transiently transfected a luciferase expression vector driven by human preproinsulin gene promoter spanning from -1998 to +237 (pINS-1998/luc) and several deletion constructs into ribo-MIN6. Furthermore, transient transfection with ribozyme vector and pINS-1998/luc into wild-type MIN6 cells was also carried out. Luciferase activity was about 9-fold higher in ribo-MIN6 cells as compared to wild-type MIN6 cells. In the transient transfection of pINS-1998/luc with gamma-GCS ribozyme vector into wild-type MIN6 cells, the luciferase activity was increased in proportion to the added amounts of ribozyme vector. In transfection with deletion constructs, two major sites were found to be critical for insulin promoter activity. For the wild-type MIN6 cells, regions important for the promoter activity were also located at regions similar to those of ribo-MIN6 cells. Our results suggest that the suppression of intracellular GSH level might, in part, regulate the insulin gene expression.

Taenia solium taeniasis/cysticercosis in Papua, Indonesia in 2001: detection of human worm carriers

A preliminary study to detect human worm carriers of Taenia solium in Papua (Irian Jaya), Indonesia was carried out using stool examinations for the detection of copro-antigens and adult proglottids after chemotherapy, and confirmation by mitochondrial DNA analysis using expelled proglottids and metacestodes developed in NOD/Shi-scid mice from eggs of expelled proglottids. Approximately 8.6% of the local population in Kama (5/58), 1 km from the local capital city centre, Wamena, were confirmed to harbour adult T. solium using these techniques.

Evaluation of tongue inspection and serology for diagnosis of Taenia solium cysticercosis in swine: usefulness of ELISA using purified glycoproteins and recombinant antigen

Evaluation of serology using glycoproteins (GPs) purified by preparative isoelectric focusing (pH 8.8) and recombinant chimeric antigen (RecTs) of Taenia solium was carried out using (1) blood samples on filter papers from pigs infected with different doses of eggs of T. solium in Mexico, (2) serum samples from pigs found infected naturally in Vietnam and Ecuador and (3) serum samples from pigs suspected to be infected with T. solium by tongue inspection in Tanzania. Antibody responses (IgG) were detectable in experimentally infected pigs confirmed harbouring 16 or more cysts at necropsy from 30 days after egg inoculation. One of three pigs naturally infected and harbouring 2.5 cysts/kg muscle and most of pigs harbouring=5.0 cysts/kg were also seropositive by ELISA. Although pigs may be infected with other taeniid species such as Taenia hydatigena, pigs harbouring this parasite were negative in ELISA. Approximately, 76 and 78% of sera from pigs having nodule(s) in the tongue (positive tongue inspection) were serologically positive by both ELISA and immunoblot, respectively. Furthermore, approximately 34 and 18% of sera from pigs having no nodules in the tongue (negative tongue inspection) were also seropositive by ELISA and immunoblot, respectively. ELISA using the two antigens was more sensitive than immunoblot and reliable for differentiation of pigs infected with cysticerci of T. solium from those either uninfected or infected with other taeniid species. Pigs without nodule by tongue inspection should be checked serologically in endemic areas.

Cysticercosis/taeniasis: recent advances in serological and molecular diagnoses

Serodiagnosis by immunoblot, using recombinant chimeric T. solium antigen and native glycoprotein antigens, has been applied for neurocysticercosis cases. Specific antibodies against both antigens were detected in serum samples from NCC patients involving multiple cysts in the brain, whereas it was not always easy to detect specific antibodies in NCC cases with a solitary cyst or calcified lesion(s). On the other hand, the diagnosis for human taeniasis or worm carriers has been routinely performed by stool examination. In this study, multiplex PCR has been established to differentiate taeniasis using Taenia mitochondrial DNA in fecal samples from worm carriers. Furthermore, the molecular identification of human taeniid cestodes by base excision sequence scanning thymine-base analysis has also been introduced. This method provides four thymine-base peak profiles unique for Asian and American/African genotypes of T. solium, T. saginata and T. asiatica. By comparing thymine base peak profiles, it is possible to differentiate human taeniid cestodes without DNA sequencing. The approaches are powerful tools for the routine diagnosis of taeniasis and the molecular identification of taeniid cestodes.

Acute effects of ethanol on feeding behavior and leptin-induced STAT3 phosphorylation in rat hypothalamus

OBJECTIVE

Drinking ethanol stimulates the appetite, producing a positive energy balance. The mechanism by which ethanol regulates the appetite in the central nervous system, however, has not been fully understood. The aim of this study is to investigate the interaction of ethanol with the satiety effect of leptin, a hormone which suppresses the appetite in the hypothalamic region.

DESIGN

: Leptin (7.5 micro g) or the same dose of phosphate buffer saline (PBS) was administered into the third ventricle (i.c.v.), 30 min after an intraperitoneal injection (i.p.) of ethanol (0.5 g/kg body weight) or the same dose of PBS.

MATERIALS

Adult male Sprague-Dawley rats weighing 290-320 g were used.

MEASUREMENTS

Food intake was measured 2, 12 and 24 h after leptin i.c.v. infusion. The tyrosine phosphorylation of signal transducer and activator transcription factor 3 (STAT3) in the hypothalamus was analyzed by Western blotting.

RESULTS

The cumulative food intakes in the saline/leptin group (saline i.p.+leptin i.c.v.) were markedly reduced to about 45% of the saline/PBS group (saline i.p.+PBS i.c.v.) at 2, 12 and 24 h time points (P<0.05, 0.001, and 0.005, respectively). As compared with the saline/leptin group, those of the ethanol/leptin group (ethanol i.p.+leptin i.c.v.) were significantly increased to the level seen in the saline/PBS group at 12 and 24 h time points (P<0.05, and P<0.005 vs the saline/leptin group, respectively). Ethanol administration resulted in about a 50% reduction of the leptin-induced STAT3 tyrosine phosphorylation seen in the hypothalamic protein as compared to that of the saline/leptin group.

CONCLUSION

These findings suggest that ethanol-induced enhancement of the appetite may, in part, result from leptin resistance transiently caused by ethanol to attenuate the leptin signal transduction.

Dogs as alternative intermediate hosts of Taenia solium in Papua (Irian Jaya), Indonesia confirmed by highly specific ELISA and immunoblot using native and recombinant antigens and mitochondrial DNA analysis

Serology (ELISA and immunoblot) using native glycoproteins, affinity purified glycoproteins, and a recombinant antigen is known to be highly specific to Taenia solium cysticercosis in humans and pigs. These techniques were applied for dogs in the highly endemic area of cysticercosis in Papua (Irian Jaya), Indonesia. Analysis of dog sera by both ELISA and immunoblot revealed 7 of 64 dogs were highly positive. Examination of two sero-positive dogs revealed cysticerci of T. solium in the brain and heart of these dogs. Mitochondrial DNA analysis confirmed that they were the same as T. solium previously confirmed from pigs and biopsies from local people from Irian Jaya. It is suggested that the life cycle of T. solium may be completed not only between humans and pigs but also between humans and dogs.

Decrease in the insulin receptor protein level by anti-insulin receptor antibodies: roles of tyrosine kinase activity and receptor internalization

To investigate the mechanism of severe impairment of insulin action in type B insulin resistance, we extracted IgG from the serum of a patient with type B insulin resistance (B-IgG) and analyzed the inhibiting effect of B-IgG not only on insulin signaling but also on IGF-I signaling in Chinese hamster ovary (CHO) cells expressing human insulin receptor or human IGF-I receptor. Preincubation with 1 mg/ml B-IgG prevented insulin-induced phosphorylation of insulin receptor and insulin receptor substrate-1 (IRS-1) but did not alter the IGF-I-induced phosphorylation of the IGF-I receptor and IRS-1. (125)I-insulin binding was inhibited by 93% after preincubation with B-IgG at 37 degrees C and was recovered up to 50% of the control value by acid washing. However, when cells were preincubated with B-IgG at 4 degrees C, the insulin binding completely recovered the control value by acid washing. (125)I-IGF-I binding was not altered by B-IgG preincubation. Immunoblot study revealed that the protein level of the insulin receptor was strongly decreased by preincubation with 1 mg/ml B-IgG at 37 degrees C, but never at 4 degrees C. The IRS-1 protein level did not change by B-IgG preincubation. In order to know the role of the insulin receptor internalization in the inhibiting effect of B-IgG, we employed CHO cells expressing mutant insulin receptors which do not undergo internalization (CHO-K1018R). B-IgG incubation of CHO-K1018R at 37 degrees C failed to decrease the protein level of the insulin receptor. The present data indicate that IgG from the diabetic patient with type B insulin resistance decreased insulin receptor protein level, probably due to the enhanced degradation rate of the insulin receptor, in which insulin receptor tyrosine kinase activity and internalization are required for this process. This effect of B-IgG was specific for the insulin receptor with no effect on either IGF-I receptor or IRS-1, as reflected by the IGF-I effectiveness on glycemic control in this patient.

Antibodies to GAD in Japanese patients classified as Type 2 diabetes at diagnosis. High titre of GAD Ab is a predictive marker for early insulin treatment--report of west Japan (Kyushu, Yamaguchi, Osaka) study for GAD Ab(+) diabetes

AIM

We evaluated the prevalence of GAD Ab in Japanese Type 2 diabetic patients treated with oral hypoglycaemic agents (OHA) and/or diet and followed GAD Ab(+) patients to assess the usefulness of GAD Ab as a marker for future insulin treatment prospectively.

METHODS

A total of 2658 Japanese Type 2 diabetic patients treated by OHA and/or diet were randomly selected between April 1996 and December 1998. The clinical characteristics at entry were assessed and patients were followed for 1-3 years.

RESULTS

The overall prevalence of GAD Ab among Type 2 diabetic patients was 2.0%. Forty-five had a history of diabetes of < or = 5 years (short history) while those with duration > 5 years (long history) totalled nine. Among them, 47% of patients with a short history did not require insulin in the follow-up period. However, none of those with a long history required insulin treatment within 2 years. Comparison of patients based on GAD titre in those with short history showed that 33% of patients in the high-titre group (> or = 20 U) required no insulin treatment in the first year of follow-up. In contrast, this proportion was 80% in the first and 67% in the second year in the low-titre group (< 20 U).

CONCLUSIONS

The prevalence of GAD Ab in Japanese patients with a short and long history of diabetes was 2.8% and 0.9%, respectively. The presence of GAD Ab in Japanese Type 2 diabetic patients with a short history of diabetes is a marker for early insulin treatment.

A phylogenetic hypothesis for the distribution of two genotypes of the pig tapeworm Taenia solium worldwide

Genetic polymorphism was determined among 13 isolates of Taenia solium from various regions using PCR-amplified sequences of 2 mitochondrial genes: cytochrome c oxidase subunit 1 and cytochrome b. The 2 phylogenies obtained were similar to each other regardless of the genes examined. The isolates from Asia (China, Thailand, Irian Jaya and India) formed a single cluster, whereas the isolates from Latin America (Mexico, Peru, Ecuador, Bolivia and Brazil) combined with those from Africa (Tanzania, Mozambique and Cameroon) to form an additional cluster. These results and historical data of swine domestication, distribution of pigs and colonization suggest that T. solium was introduced recently into Latin America and Africa from different regions of Europe during the colonial age, which started 500 years ago, and that the tapeworm of another origin independently spread in Asian countries.

Analysis of glucose tolerance in twin gestations using an oral glucose load

The effect of twin gestation on carbohydrate metabolism was evaluated using a 75 g oral glucose tolerance test (75 g OGTT). A 75 g OGTT was performed in 63 twin gestations and 3 791 singleton gestations during the third trimester. Plasma glucose concentrations were measured in the pregnant women under fasting conditions as well as 30 min, 1 h, and 2 h after ingestion of glucose (75 g oral load), and serum insulin concentrations were measured in fasting and 30 min post-ingestion samples. Women with twin gestations showed significantly lower plasma glucose concentrations during fasting and 30 min after the glucose load in the samples taken than those with singleton gestations. No significant difference in serum glucose concentrations was found in the other specimens. There were no cases of gestational diabetes mellitus in our study. Although women with twin gestations demonstrated lower plasma glucose concentrations than women with singleton gestations, the difference observed was subtle. We could not find any significant differences in these plasma glucose values as used to define a pathologic OGTT between twin and singleton pregnancies, with the exception of the fasting value.

NBT-II carcinoma behaviour is not dependent on cell-cell communication through gap junctions

To study the mechanism(s) underlying the proliferation of heterogeneous cell populations within a solid tumour, the NBT-II rat bladder carcinoma system was used. It has been first investigated whether the different cell populations are coupled through gap junctions (GJIC). Cells overexpressing the Cx43 were generated to test for any tumour suppressive activity in vivo. To determine whether GJIC is essential for tumour proliferation and the establishment of a cooperative community effect, NBT-II cells that are incompetent for cell coupling were generated. The data report that (i) carcinoma cells expressing or not FGF-1 are coupled through GJIC in vitro and in coculture and express the gap junction protein Cx43, (ii) overexpression of Cx43 in these cells does not affect their in vitro coupling capacities and in vivo tumourigenic growth properties, (iii) inhibition of GJIC through antisense strategy has no in vivo obvious consequence on the tumour growth properties of the carcinoma, and (iv) the community effect between two carcinoma cell populations does not critically involve cell coupling through gap junctions.

Separation of highly fluorescent proteins by SDS-PAGE in Acroporidae corals

This study characterized the spectral properties of Acropora tenuis, A. nasuta, A. secale, and A. aspera, all of which showed strong colorful fluorescence under ultraviolet light-A (black light). The emission maxima of fluorescence from the intact corals were 517, 482, 484, and 514 nm in A. tenuis, A. nasuta, A. secale, and A. aspera, respectively. Using a soluble fraction of cell-free extract of the corals, we applied a method of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to separate each fluorescent protein component contained in the corals. Green fluorescent bands were detected in all Acropora examined, although their apparent molecular mass and relative content were different. A. aspera had two orange bands in addition to the green one. The major excitation and emission peaks of the orange fluorescence bands were almost identical (476 and 478 nm), however, they were discernible by their spectral profiles and molecular masses. Some biochemical properties of the highly fluorescent proteins of Acropora are described and implications of the results are discussed.

Association between IA-2 autoantibody epitope specificities and age of onset in Japanese patients with autoimmune diabetes

The IA-2 is a major autoantigen of type 1 diabetes belonging to the protein tyrosine phosphatase family. We report on the humoral autoimmunity to an alternatively-spliced variant of IA-2 (IA-2 variant) and autoimmune-mediated diabetes age of onset association with IA-2 autoantibody epitope specificities, in 144 recent-onset patients with type 1 diabetes and 54 GAD autoantibody-positive patients with type 2 diabetes. The cytoplasmic domain of IA-2 (IA-2ic) detected a somewhat greater proportion of patients expressing autoantibodies than IA-2 variant (56%vs. 52% of patients with type 1 diabetes and 17%vs. 9% of GAD autoantibody-positive patients with type 2 diabetes). Conversely, only 1% of IA-2 variant autoantibody-positive patients failed to react to IA-2ic construct. Among 80 patients with type 1 diabetes who were positive for autoantibodies to IA-2ic, 8% recognized the juxtamembrane region (JM, representing amino acids 601-629) only, 64% bound the protein tyrosine phosphatase (PTP)-like domain of IA-2 only, and 29% bound both JM and PTP epitopes. Autoantibodies to the PTP-like domain were prevalent in children and adolescents with type 1 diabetes. The age of disease onset in patients with IA-2JM autoantibodies only, was significantly higher than those in patients reacted with the PTP-like domain of IA-2 (P< 0.02). Among GAD autoantibody-positive patients with type 2 diabetes reacted with IA-2ic, 44% bound the JM region only, and 33% bound epitopes in the PTP-like domain only; 22% had autoantibodies to both regions. The frequency of GAD autoantibody-positive patients with type 2 diabetes positive for autoantibodies to the JM region only, was significantly higher than that in patients with type 1 diabetes (P< 0.01). IA-2PTP autoantibodies were significantly associated with HLA-DR4, while the additional reactivity to IA-2JM was associated with HLA-DR9 allele. These results suggest that autoantibody recognition of IA-2 epitopes in autoimmune diabetes is associated with age of disease onset, which may reflect the intensity of the beta-cell destruction process.

Gap junctions and fluid flow response in MC3T3-E1 cells

In the current study, we examined the role of gap junctions in oscillatory fluid flow-induced changes in intracellular Ca(2+) concentration and prostaglandin release in osteoblastic cells. This work was completed in MC3T3-E1 cells with intact gap junctional communication as well as in MC3T3-E1 cells rendered communication deficient through expression of a dominant-negative connexin. Our results demonstrate that MC3T3-E1 cells with intact gap junctions respond to oscillatory fluid flow with significant increases in prostaglandin E(2) (PGE(2)) release, whereas cells with diminished gap junctional communication do not. Furthermore, we found that cytosolic Ca(2+) (Ca) response was unaltered by the disruption in gap junctional communication and was not significantly different among the cell lines. Thus our results suggest that gap junctions contribute to the PGE(2) but not to the Ca response to oscillatory fluid flow. These findings implicate gap junctional intercellular communication (GJIC) in bone cell ensemble responsiveness to oscillatory fluid flow and suggest that gap junctions and GJIC play a pivotal role in mechanotransduction mechanisms in bone.

Relationship between age-related increases in rat liver lipid peroxidation and bile canalicular plasma membrane fluidity

Aging is associated with increased cellular levels of lipid peroxides and reactive oxygen species. This increase in the radical species may affect membrane fluidity and consequently membrane functions. We attempted to determine whether age-related increases in lipid peroxide and reactive oxygen species levels affect the annular fluidity of the bile canalicular plasma membrane in young (2-3 weeks old), adult (20 weeks old) and old (100 weeks old) rats. Hepatic levels of lipid peroxides measured with thiobarbituric acid reactive substances (TBARS), reactive oxygen species and reduced glutathione were significantly higher in the old rats than in the young and adult rats. Arachidonic acid (AA) levels increased and docosahexaenoic acid (DHA) levels decreased in the isolated canalicular plasma membrane of the old rats, and the ratio of DHA to AA thus decreased significantly with rat aging. Hepatic TBARS levels correlated negatively with molar ratios of DHA to AA. The annular fluidity of the bile canalicular plasma membrane decreased significantly in the old rats compared with that in the young and adult rats. These results suggest that the age-related decrease in DHA content of the bile canalicular plasma membrane and the molar ratio of DHA to AA may be associated with age-related deterioration of membrane annular fluidity.

Control of intracellular movement of connexins by E-cadherin in murine skin papilloma cells

The gap junctional intercellular communication-deficient mouse skin papilloma cell line P3/22 expresses Cx43 but not E-cadherin. The E-cadherin gene-transfected cells (P3E1) communicate in a calcium-dependent manner and they were used to study how E-cadherin restores the function of connexins. At low calcium, Cx43 molecules remain in the cytoplasm of P3E1 cells and appear at cell-cell contact areas only in high-calcium medium. While Cx43 is unphosphorylated in P3E1 cells in low-calcium medium, two phosphorylated bands appeared at high calcium. However, when Cx26, which has no C-terminal tail that can undergo phosphorylation, was expressed in P3E1 cells, this connexin also moved to the plasma membrane after the calcium shift and partly colocalized with Cx43, suggesting that C-terminal phosphorylation is not essential for E-cadherin-mediated intracellular transport of connexins. In low calcium, both Cx26 and Cx43 remained and colocalized in the endoplasmic reticulum. As early as 30 min after the shift to high-calcium medium, both Cx43 and Cx26 began to accumulate in the Golgi apparatus. Intracellular movement of connexins to the cytoplasmic membrane at high calcium was effectively blocked by cytochalasin D and brefeldin A. These results suggest that E-cadherin junction formation at high calcium leads to formation of actin cables, which directly or indirectly transport connexins from the cytoplasm to the cell-cell contact membranes via the Golgi apparatus.

Relationships of serum levels of insulinlike growth factors with indices of bone metabolism and nutritional conditions in hemodialysis patients

Insulinlike growth factor (IGF) I and IGF-II are synthesized in osteoblasts and stimulate proliferation, differentiation, and matrix synthesis in these cells. There is some evidence that IGFs act on bone cells not only by paracrine but also by endocrine pathways, suggesting that circulating IGFs may be of importance for the regulation of bone metabolism. On the other hand, the serum IGF-I level is also thought to be a good indicator of the nutritional conditions in hemodialysis patients. The present study was performed to analyze the correlations of circulating levels of IGF-I, IGF-II, IGF-binding protein (IGFBP) 1 and IGFBP-3 with biochemical markers of bone metabolism and parameters of the urea kinetic model which reflect nutritional conditions in hemodialysis patients. We also examined the differences between these relationships in male and female patients on hemodialysis. Sixty-two hemodialysis patients, 36 men (male group) and 26 women (female group), were included in this study. We measured the serum levels of IGF-I, IGF-II, IGFBP-1, and IGFBP-3. The bone mineral content (BMC) of the radius was measured by dual-energy X-ray absorptiometry. We calculated Kt/V, protein catabolic rate, and percent creatinine generation rate (%CGR). We also examined the relationships between serum levels of IGFs and BMC and the parameters of the urea kinetic model. It was found that the serum levels of IGF-I in the hemodialysis patients were almost the same as those in the control group. However, the serum levels of IGF-II, IGFBP-1, and IGFBP-3 in the hemodialysis patients were significantly higher than those in the control group. In the male group, the serum IGF-I levels showed a significant correlation with both serum intact parathyroid hormone levels and BMC, but no significant correlations between these indices were found in the female group. The serum levels of both IGF-I and IGF-II showed significant correlations with %CGR in the male group, but not in the female group. Stepwise multiple regression analysis was performed to clarify the relationship between serum levels of IGFs and BMC or %CGR. It was found that age, hemodialysis duration, serum intact parathyroid hormone levels, and sex were independent factors associated with BMC. The %CGR was associated independently with serum levels of IGF-I, and IGF-II and with the presence of diabetes mellitus. In conclusion, it is thought that serum levels of IGF-I and IGF-II can be used as indices of nutritional conditions in hemodialysis patients. However, the serum IGF-I level cannot be used as a marker of bone metabolism in hemodialysis patients.