Characterization of the oral and faecal microbiota associated with atopic dermatitis in dogs selected from a purebred Shiba Inu colony.

Atopic dermatitis (AD) is a chronic and relapsing multifactorial inflammatory skin disease that also affects dogs. The oral and gut microbiota are associated with many disorders, including allergy. Few studies have addressed the oral and gut microbiota in dogs, although the skin microbiota has been studied relatively well in these animals. Here, we studied the AD-associated oral and gut microbiota in 16 healthy and 9 AD dogs from a purebred Shiba Inu colony. We found that the diversity of the oral microbiota was significantly different among the dogs, whereas no significant difference was observed in the gut microbiota. Moreover, a differential abundance analysis detected the Family_XIII_AD3011_group (Anaerovoracaceae) in the gut microbiota of AD dogs; however, no bacterial taxa were detected in the oral microbiota. Third, the comparison of the microbial co-occurrence patterns between AD and healthy dogs identified differential networks in which the bacteria in the oral microbiota that were most strongly associated with AD were related to human periodontitis, whereas those in the gut microbiota were related to dysbiosis and gut inflammation. These results suggest that AD can alter the oral and gut microbiota in dogs.

Subpopulation Primers Essential for Exhaustive Detection of Diverse Hemagglutinin Genes of H5 Subtype Avian Influenza Viruses by Loop-Mediated Isothermal Amplification Method.

Loop-mediated isothermal amplification (LAMP) is a potential screening test for avian influenza (AI), but its narrow detection spectrum limits its applications. To improve this narrow detection spectrum, 3 types of primers were compared for detection of diverse H5 subtype hemagglutinin (HA) genes. Four and 6 genes, of 10 genetically different H5 HA genes tested, were detected with S primers specific for A/duck/Tsukuba/9/2005 (H5N2) and with M primers (which contained mixed bases), respectively. In contrast, all 10 HA genes became positive with population primers (P primers) (a mixture of primers designed for each subpopulation of 2,202 HA genes). Our study indicated that the P primers for the forward inner primer (FIP) and backward inner primer (BIP) sites were essential for exhaustive detection, whereas those for the F3, forward loop (FL), backward loop (BL), and B3 sites were exchangeable with M primers. A base mismatch experiment demonstrated that HA genes with ≤2 base mismatches per primer site and ≤10 base mismatches per HA gene were amplifiable. Reverse transcription-LAMP was broadly reactive, specific for H5 subtype HA genes, and applicable to field samples, with the sensitivity of real-time PCR. The in silico analysis suggested that most H5 HA genes (2,586 positive genes/2,588 genes tested) registered in the GenBank database might be amplifiable. These results indicate that the use of subpopulation primers in LAMP allows exhaustive detection of diverse HA genes and H5 LAMP can be used as a reliable AI screening test in general diagnostic laboratories.

Time-dependent distinct roles of Toll-like receptor 4 in a house dust mite-induced asthma mouse model.

House dust mites (HDMs) are a common source of allergens that trigger both allergen-specific and innate immune responses in humans. Here, we examined the effect of allergen concentration and the involvement of Toll-like receptor 4 (TLR4) in the process of sensitization to house dust mite allergens in an HDM extract-induced asthma mouse model.　Intranasal administration of HDM extract induced an immunoglobulin E response and eosinophilic inflammation in a dose-dependent manner from 2.5 to 30 µg/dose. In TLR4-knockout mice, the infiltration of eosinophils and neutrophils into the lung was decreased compared with that in wild-type mice in the early phase of inflammation (total of three doses). However, in the late phase of inflammation (total of seven doses), eosinophil infiltration was significantly greater in TLR4-knockout mice than in wild-type mice. This suggests that the roles of TLR4 signaling are different between the early phase and the later phase of HDM allergen-induced inflammation. Thus, innate immune response through TLR4 regulated the response to HDM allergens, and the regulation was altered during the phase of inflammation.

Cancer is an independent predictor of poor outcomes in patients following intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Patients with cancer have been reported to have poorer outcomes following intracerebral hemorrhage (ICH) than those without cancer, but the findings were not consistent between studies. The aim of this study was to test the hypothesis that cancer is associated with poor outcomes following ICH. METHODS: In all, 3137 consecutive patients admitted to the stroke unit of Osaka University Hospital were reviewed. Patients diagnosed with ICH were extracted and divided into two groups according to the presence of cancer. ICH characteristics were compared between the groups. The outcomes were measured using the 30-day and 90-day modified Rankin Scale (mRS). RESULTS: Amongst the 399 ICH patients (37.1% women; median age 66 years), the frequency of cancer was 15.3%. Of these, 70.5% of patients had distant metastatic cancers. Compared to controls, cancer patients were comparable in the Glasgow Coma Scale, hematoma volume and the frequency of infratentorial location and intraventricular hemorrhage extension, but had poorer outcomes following ICH. Ordinal logistic regression analysis revealed that cancer was independently associated with poor outcomes following ICH (odds ratio 5.14; 95% confidence interval 2.63-10.06). Adjustment was made for the covariates age, sex, time from onset to admission, prior use of antithrombotic agents, pre-stroke mRS, Glasgow Coma Scale, hematoma volume, infratentorial location and intraventricular hemorrhage extension. When the analysis was performed using data from individuals with localized cancer, the effect remained significant after assessment with 90-day mRS but not after that with 30-day mRS. CONCLUSIONS: The results suggest that cancer, especially distant metastatic cancer, is an independent predictor of poorer outcomes following ICH.

Plasma D-dimer levels and ischaemic lesions in multiple vascular regions can predict occult cancer in patients with cryptogenic stroke.

BACKGROUND AND PURPOSE: Cancer patients with cryptogenic stroke often have high plasma D-dimer levels and lesions in multiple vascular regions. Hence, if patients with cryptogenic stroke display such characteristics, occult cancer could be predicted. This study aimed to investigate the clinical characteristics of cryptogenic stroke as the first manifestation of occult cancer and to determine whether plasma D-dimer levels and lesions in multiple vascular regions can predict occult cancer in patients with cryptogenic stroke. METHODS: Between January 2006 and October 2015, data on 1225 patients with acute ischaemic stroke were extracted from the stroke database of Osaka University Hospital. Among them, 184 patients were classified as having cryptogenic stroke, and 120 patients without a diagnosis of cancer at stroke onset were identified. Clinical variables were analyzed between cryptogenic stroke patients with and without occult cancer. RESULTS: Among 120 cryptogenic stroke patients without a diagnosis of cancer, 12 patients had occult cancer. The body mass index, hemoglobin levels and albumin levels were lower; plasma D-dimer and high-sensitivity C-reactive protein levels were higher; and lesions in multiple vascular regions were more common in patients with than in those without occult cancer. Multiple logistic regression analysis revealed that plasma D-dimer levels (odds ratio, 3.48; 95% confidence interval, 1.68-8.33; P = 0.002) and lesions in multiple vascular regions (odds ratio, 7.40; 95% confidence interval, 1.70-39.45; P = 0.01) independently predicted occult cancer. CONCLUSIONS: High plasma D-dimer levels and lesions in multiple vascular regions can be used to predict occult cancer in patients with cryptogenic stroke.

Interleukin-6, interleukin-6 receptor gene variant, small-vessel disease and incident dementia.

BACKGROUND AND PURPOSE: Mixed neurogenerative and vascular dementia has emerged as the leading cause of dementia in the elderly. Inflammation is implicated in atherosclerosis, cerebral small-vessel disease (SVD) as well as cognitive impairment. However, longitudinal data on the predictive value of circulating inflammatory markers including gene variants and magnetic resonance imaging (MRI) findings in incident dementia are scarce. It was investigated whether circulating interleukin-6 (IL-6), C-reactive protein (CRP) and gene variants increase dementia risk. METHODS: In a cohort of Japanese participants with vascular risk factors in an observational study from 2001, the association between baseline IL-6, CRP levels, gene variants [interleukin-6 receptor (IL-6R), rs2228145; IL-6, rs2097677; CRP, rs3093059] and incident all-cause dementia was evaluated. Baseline MRI was used to determine SVD (lacuna, white matter hyperintensities) and atrophy (medial-temporal lobe atrophy, bicaudate ratio). Cox proportional hazards analyses were performed for predictors of dementia, adjusting for age, sex, apolipoprotein Eε4, education, cerebrovascular events, vascular risk factors and MRI findings. RESULTS: Of 803 subjects (mean 67.0 ± 8.5 years, males 59%), during a mean of 7.5 ± 3.2 years follow-up, 60 incident dementia patients (Alzheimer's disease 31; vascular dementia 17; mixed-type six; other six) were diagnosed. In multivariable analyses adjusted for age, sex, cerebrovascular events, MRI findings and IL-6R variant (rs2228145), IL-6 levels (relative risk 1.68, P = 0.048) or highest tertile (relative risk 2.38, P = 0.031) for all-cause dementia remained significant. Although subjects with rs2228145 carrier had significantly higher IL-6 levels, a significant association between rs2228145 and dementia was not observed. Conversely, CRP and remaining gene variants were not associated with dementia. CONCLUSIONS: The deleterious effect of higher IL-6 on dementia remains consistent irrespective of conventional risk factors, MRI findings and IL-6R variant.

Serum high-molecular-weight adiponectin level and incident dementia in patients with vascular risk factors.

BACKGROUND AND PURPOSE: The involvement of metabolic factors in the development of dementia has received much attention. However, previous studies have yielded conflicting results regarding how blood adipocytokine level impacts cognitive decline and dementia. This study aimed to clarify whether serum high-molecular-weight (HMW) adiponectin level is related to incident dementia. METHODS: Data were from 466 patients (mean age 67.8 years, male 57%)--who had normal cognitive function and received brain magnetic resonance imaging--from amongst the 1106 patients in the Osaka Follow-up Study for Carotid Atherosclerosis, Part 2, a prospective cohort study of cardiovascular events and dementia amongst patients with vascular risk factors enrolled between 2001 and 2009. Baseline HMW adiponectin levels were measured using frozen serum. Dementia occurrence was examined in June 2013. RESULTS: Serum HMW adiponectin level was 4.33 ± 2.95 µg/ml; the levels were lower in men than in women and negatively correlated with body mass index. During the follow-up period (median 6.9 years), 47 patients had incident dementia including Alzheimer's disease dementia (27), vascular dementia (13), mixed dementia (four), other dementia (three). Risks of dementia in patients with high versus low HMW adiponectin levels were almost identical (P = 0.689). No association was found between adiponectin levels and Alzheimer's disease dementia or vascular dementia in the whole group or amongst men and women separately. CONCLUSIONS: This study demonstrated that serum HMW adiponectin level has little association with future dementia. Determination of metabolic factors involved in dementia requires evaluation of other biomarkers or parameters.

Association between carotid stenosis or lacunar infarction and incident dementia in patients with vascular risk factors.

BACKGROUND AND PURPOSE: The association between vascular risk factors and dementia is of interest. Several studies have shown that cerebral small vessel disease (SVD) is associated with dementia. However, the association between cerebral large vessel disease (LVD) and dementia has not been thoroughly examined. METHODS: The Osaka Follow-up Study for Carotid Atherosclerosis, Part 2, was a prospective cohort study of cardiovascular events and dementia in which patients (n = 1106) with vascular risk factors underwent carotid ultrasound. Of these patients, 600 who had normal cognitive function were included and underwent brain magnetic resonance imaging. The presence of lacunar infarction and carotid stenosis served as markers for SVD and LVD, respectively. RESULTS: Amongst 600 patients (mean 68 years, 57% men), 261 (44%) showed lacunar infarction and 94 (16%) showed carotid stenosis. During the follow-up period (median 8.0 years), 57 patients had incident dementia. Patients with carotid stenosis and lacunar infarction were significantly more likely to be diagnosed with dementia (log-rank test, P = 0.037 and P < 0.001, respectively). The association between lacunar infarction and dementia remained significant after adjusting for risk factors including stroke history, apolipoprotein E genotype and years of education (hazard ratio 2.64, 95% confidence interval 1.22-6.09). However, the presence of carotid stenosis was not associated with incident dementia after adjusting for age and sex (P = 0.477). CONCLUSIONS: This study demonstrated that carotid stenosis had little association with dementia, but lacunar infarction had a significant association. The impact of SVD on dementia could be much greater than that of LVD.

Sulcus subarachnoid hemorrhage is a common stroke subtype in patients with implanted left ventricular assist devices.

BACKGROUND AND PURPOSE: Stroke is one of the major complications observed in patients with an implanted left ventricular assist device (LVAD). The purpose of this study was to clarify the types and characteristics of acute stroke in patients after LVAD implantation by using brain computed tomography (CT) findings. METHODS: Between 2005 and 2012, 110 consecutive patients who underwent LVAD implantation were reviewed. The most commonly used device was the pulsatile extracorporeal LVAD. Amongst them, 49 patients suffered from acute stroke at least once with a total of 115 stroke events. The clinical categories, lesion sites, laboratory data and CT findings of each acute stroke event were analyzed. RESULTS: Cerebral infarction (35 patients, 72 events), cerebral hemorrhage (25 patients, 31 events) and subarachnoid hemorrhage (SAH) (23 patients, 33 events) were identified. A mean of 2.3 stroke events occurred per person. Of the 72 infarction events, multiple infarctions were observed in 29 events. Of the cerebral hemorrhage events (n = 31), almost all were subcortical lesions (n = 27) and none were observed in the basal ganglia. Of the 23 patients with SAH events (n = 33), SAH localized within a single sulcus, sulcus SAH, was observed in 25 events. CONCLUSIONS: Computed tomography findings of acute stroke after implantation of an LVAD are characteristically multifocal cortical lesions, regardless of brain infarction and hemorrhage. Unexpectedly, sulcus SAH was a common stroke subtype in patients with implanted LVADs. Sulcus SAH should be carefully examined in patients after LVAD implantation, when they complain of non-specific neurological complaints.

Thyroid antibodies are associated with stenotic lesions in the terminal portion of the internal carotid artery.

BACKGROUND AND PURPOSE: Several studies have reported moyamoya syndrome associated with thyroid disease, and the mechanism involved in this relationship is unknown. This study aimed to clarify the involvement of thyroid antibodies and thyroid function in intracranial arterial stenosis. METHODS: The study included 30 patients <65 years of age with intracranial arterial steno-occlusion. Patients with definitive moyamoya disease were excluded. Thyroid function and thyroid antibody levels were evaluated. The steno-occlusive site and the presence of moyamoya vessels were evaluated using digital subtraction angiography. The characteristics of intracranial arterial lesions were compared between patients with and without elevated thyroid antibody levels, and between patients with increased thyroid function and those with normal thyroid function. RESULTS: Five patients had increased thyroid function and seven had elevated thyroid antibody levels. Four were diagnosed with Graves' disease, 13 with atherosclerotic intracranial stenosis, two with intracranial arterial dissection, one with vasculitis syndrome and 10 with intracranial stenosis of unknown cause. All patients with Graves' disease and patients with elevated antithyroid peroxidase antibody levels had steno-occlusion in the terminal portion of the internal carotid arteries, whereas most of the patients with normal thyroid function or without elevated thyroid antibody levels had stenosis in the middle cerebral arteries. CONCLUSIONS: In young and middle-aged patients, a lesion in the terminal portion of the internal carotid artery was associated with elevated thyroid antibody levels and increased thyroid function. Stenoses found in the terminal portion of the internal carotid artery and immune-mediated thyroid diseases may share a common background.

Evaluation of chlorinated benz[a]anthracene on hepatic toxicity in rats and mutagenic activity in Salmonella typhimurium.

Chlorinated benz[a]anthracenes (Cl-BaA) are halogenated aromatic compounds (typified by dioxins) found in the environment at relatively high concentrations. Fischer 344 rats were intragastrically administered 0, 1, or 10 mg of Cl-BaA or its parent compound benz[a]anthracene (BaA) per kg of body weight for 14 consecutive days. Both chemicals at 10 mg/kg/day inhibited the gain in body weight, and consequent increase in relative liver weight. Hepatic gene expression of cytochrome P450 (CYP) 1A1, 1A2, and 1B1 was significantly stimulated by administration of BaA (10 mg/kg/day) compared with the control. After administration of Cl-BaA, only the CYP1A2 gene was significantly induced, even at the lower dosage; CYP1A1 and 1B1 mRNA levels remained unchanged in Cl-BaA-treated rats compared with controls. To elucidate the role of such Cl-BaA exposure and induced CYPs at toxicity onset, we investigated the mutagenicity of BaA and Cl-BaA using Salmonella typhimurium TA98 and TA100. BaA and Cl-BaA at 10 µg/plate produced positive results in both strains in the presence of rat S-9. Incubation of Cl-BaA with recombinant rat CYP1A2 produced a significantly higher number of revertant colonies in TA98 and TA100 than in controls, but no such change was observed for BaA. In conclusion, BaA changes its own physiological and toxicological actions by its chlorination; (1) daily exposure to Cl-BaA selectively induces hepatic CYP1A2 in rats and (2) Cl-BaA induces frameshift mutations in the presence of CYP1A2, although BaA does not exert mutagenicity. This indicates that CYP1A2 may metabolize Cl-BaA to active forms.

Expression pattern of REIC/Dkk-3 in mouse squamous epithelia.

The REIC/Dkk (reduced expression in immortalized cells/Dickkopf-3) gene was originally identified as a tumour-suppressor gene with reduced expression in immortalized cells, cancer-cell lines and tumour tissues. Of the four members of the Dkk family, the REIC/Dkk-3 protein is unique in terms of DNA sequence, expression profiles and biological functions. In this study, we investigated and compared the expression patterns of the REIC/Dkk-3 protein in mouse squamous epithelia. Expression of REIC/Dkk-3 in the back skin was localized to the upper layer of the interfollicular epidermis, and the inner root sheath of hair follicles. Expression of REIC/Dkk-3 was detected in the ear skin, oral mucosa, tongue, oesophagus, uterine cervix, footpad and tail skin, but not in the cornea. Interestingly, expression was localized to the upper layers of these epithelial tissues. The physiological function of REIC/Dkk-3 is still unclear, but our detailed observation highlight its unique expression pattern in squamous epithelia.

Step frequency and lower extremity loading during running.

The purpose of the present study was to ascertain whether increase in step frequency at a given velocity during running reduces the lower extremity loading variables, which is associated with tibial stress fracture in runner. We hypothesized that the lower extremity loading variables at a given speed would be minimized at around +15% f step. 10 male subjects were asked to run at 2.5 m/s on a treadmill-mounted force platform. 5 step frequencies were controlled using a metronome: the preferred, below preferred (-15 and -30%) and above preferred (+15 and +30%). From the vertical ground reaction force, we measured following lower extremity loading variables; vertical impact peak (VIP), vertical instantaneous loading rate (VILR) and vertical average loading rate (VALR). We found that there were significant differences in lower extremity loading variables among 5 step frequency conditions. Furthermore, quadratic regression analyses revealed that the minimum loading variable frequencies were 17.25, 17.55, and 18.07% of preferred step frequency for VIP, VILR and VIAR, respectively. Thus, adopting a step frequency greater than one's preferred may be practical in reducing the risk of developing a tibial stress fracture by decreasing lower extremity loading variables.

[Intermittent opening of a mechanical mitral valve prosthesis due to pannus formation; report of a case].

A 76-year-old woman with a history of severe mitral valve stenosis had undergone mitral valve replacement with a 27 mm St. Jude Medical (SJM) valve in 1991. Follow-up transthoracic echocardiography revealed an increase in the pressure gradient across the mitral prosthesis 16 years after the surgery. Prosthetic valve dysfunction was suspected, but transesophageal echocardiography and cineradiography failed to show mechanical valve dysfunction. Two years later, she presented with dyspnea on exertion and leg edema. Cineradiography revealed intermittent restriction of the opening of the mechanical valve leaflet approximately every 10 beats. Thus, we diagnosed intermittent prosthetic valve dysfunction and performed a reoperation. On inspection of the prosthesis, we observed semicircular pannus formation around the posterior leaflet in the ventricular side. It was considered that the pannus tissue had interfered with 1 leaflet opening of the mitral valve prosthesis, resulting in intermittent valve dysfunction. We replaced the prosthesis with a new 25 mm SJM valve. The patient was discharged after confirmation of normal prosthetic function.

Stereotactic radiotherapy for hepatocellular carcinoma induced by hepatitis C and the relationships of changes in carbohydrate antigen 19-9 with AFP and PIVKA-II.

PURPOSE: Assessing the therapeutic effects of stereotactic body radiotherapy (SBRT) for hepatocellular carcinoma (HCC) takes time. Purpose of our study was to explore the relationships of changes in carbohydrate antigen 19-9 (CA 19-9) with those in the existing markers alpha-fetoprotein (AFP) and protein induced by vitamin K absence or antagonist-II (PIVKA-II). PATIENTS AND METHODS: The subjects were 16 patients who underwent SBRT for solitary HCC ≤3cm induced by hepatitis C between June 2016 and July 2019. Observation periods ranged from 8-43 (median: 28) months, ages from 59-85 (median: 65) years. RESULTS: Changes in CA 19-9 levels after SBRT were categorised into three patterns: 1) a transient elevation followed by a decline (75%); 2) a transient decline followed by an elevation (18.8%); and 3) no change (6.3%). Among patients showing a transient CA 19-9 elevation followed by a decline, which was the most frequent pattern, 75% showed these changes in synchronisation with AFP and preceded the changes in PIVKA-II, while in the other 25%, CA 19-9 changes were in synchronisation with PIVKA-II and preceded those in AFP. At the time of recurrence, 62.5% showed a continuous CA 19-9 elevation, either in synchronisation with other markers or by itself. CONCLUSIONS: This is the first investigation of changes in CA 19-9 levels after SBRT for HCC induced by hepatitis C. Characteristic changes in CA 19-9, AFP, and PIVKA-II levels were observed as responses after treatment. As for its correlations with tumour markers, the acute responses of PIVKA-II tended to be slower than those of CA 19-9 and AFP. Although the sample size was small, our findings raise the possibility that measuring these 3 biomarkers after SBRT may be useful for monitoring patients for HCC recurrence.

Serum inflammatory proteins and frontal lobe dysfunction in patients with cardiovascular risk factors.

BACKGROUND: Recent studies have shown that the levels of circulating inflammatory markers are associated with cognitive decline and cerebral small-vessel disease. Frontal lobe dysfunction is believed to be a relatively characteristic neuropsychological symptom in vascular cognitive impairment caused by cerebral small-vessel disease. The purpose of this study was to investigate whether the levels of serum inflammatory markers are associated with frontal lobe dysfunction, particularly executive dysfunction. METHODS: Between January 2003 and September 2007, 388 patients who had one or more atherosclerotic risk factors and subsequently underwent brain MRI and neuropsychological testing including mini-mental state examination (MMSE), frontal assessment battery (FAB), and modified Stroop test were enrolled in this study. We evaluated the effect of serum levels of inflammatory markers and white matter lesions on frontal lobe function. RESULTS: The FAB score was negatively correlated with serum inflammatory marker levels (hsCRP; r = -0.170, IL-6; r = -0.143, IL-18; r = -0.175) and white matter lesions. In the modified Stroop test, interference measure was positively correlated with the levels of hsCRP (r = -0.198), and IL-18 (r = -0.152), and white matter lesions. However, the MMSE score was not correlated with either inflammatory marker levels. The association between hsCRP and FAB score or interference measure remained significant when controlling for other confounding factors and MRI findings. CONCLUSIONS: The circulating level of hsCRP is associated with frontal lobe dysfunction in patients with cardiovascular risk factors independent of white matter lesions in brain MRI.

Membrane topogenesis of a type I signal-anchor protein, mouse synaptotagmin II, on the endoplasmic reticulum.

Synaptotagmin II is a type I signal-anchor protein, in which the NH(2)-terminal domain of 60 residues (N-domain) is located within the lumenal space of the membrane and the following hydrophobic region (H-region) shows transmembrane topology. We explored the early steps of cotranslational integration of this molecule on the endoplasmic reticulum membrane and demonstrated the following: (a) The translocation of the N-domain occurs immediately after the H-region and the successive positively charged residues emerge from the ribosome. (b) Positively charged residues that follow the H-region are essential for maintaining the correct topology. (c) It is possible to dissect the lengths of the nascent polypeptide chains which are required for ER targeting of the ribosome and for translocation of the N-domain, thereby demonstrating that different nascent polypeptide chain lengths are required for membrane targeting and N-domain translocation. (d) The H-region is sufficiently long for membrane integration. (e) Proline residues preceding H-region are critical for N-domain translocation, but not for ER targeting. The proline can be replaced with amino acid with low helical propensity.

Characterization of the signal that directs Tom20 to the mitochondrial outer membrane.

Tom20 is a major receptor of the mitochondrial preprotein translocation system and is bound to the outer membrane through the NH(2)-terminal transmembrane domain (TMD) in an Nin-Ccyt orientation. We analyzed the mitochondria-targeting signal of rat Tom20 (rTom20) in COS-7 cells, using green fluorescent protein (GFP) as the reporter by systematically introducing deletions or mutations into the TMD or the flanking regions. Moderate TMD hydrophobicity and a net positive charge within five residues of the COOH-terminal flanking region were both critical for mitochondria targeting. Constructs without net positive charges within the flanking region, as well as those with high TMD hydrophobicity, were targeted to the ER-Golgi compartments. Intracellular localization of rTom20-GFP fusions, determined by fluorescence microscopy, was further verified by cell fractionation. The signal recognition particle (SRP)-induced translation arrest and photo-cross-linking demonstrated that SRP recognized the TMD of rTom20-GFP, but with reduced affinity, while the positive charge at the COOH-terminal flanking segment inhibited the translation arrest. The mitochondria-targeting signal identified in vivo also functioned in the in vitro system. We conclude that NH(2)-terminal TMD with a moderate hydrophobicity and a net positive charge in the COOH-terminal flanking region function as the mitochondria-targeting signal of the outer membrane proteins, evading SRP-dependent ER targeting.

Relationship between contact inhibition and intranuclear S100C of normal human fibroblasts.

Many lines of evidence indicate that neoplastic transformation of cells occurs by a multistep process. For neoplastic transformation of normal human cells, they must be first immortalized and then be converted into neoplastic cells. It is well known that the immortalization is a critical step for the neoplastic transformation of cells and that the immortal phenotype is recessive. Thus, we investigated proteins downregulated in immortalized cells by two-dimensional gel electrophoresis. As a result, S100C, a Ca(2+)-binding protein, was dramatically downregulated in immortalized human fibroblasts compared with their normal counterparts. When the cells reached confluence, S100C was phosphorylated on threonine 10. Then the phosphorylated S100C moved to and accumulated in the nuclei of normal cells, whereas in immortalized cells it was not phosphorylated and remained in the cytoplasm. Microinjection of the anti-S100C antibody into normal confluent quiescent cells induced DNA synthesis. Furthermore, when exogenous S100C was compelled to localize in the nuclei of HeLa cells, their DNA synthesis was remarkably inhibited with increase in cyclin-dependent kinase inhibitors such as p16(Ink4a) and p21(Waf1). These data indicate the possible involvement of nuclear S100C in the contact inhibition of cell growth.

Prevention of acute liver failure in rats with reversibly immortalized human hepatocytes.

Because of a critical shortage in suitable organs, many patients with terminal liver disease die each year before liver transplantation can be performed. Transplantation of isolated hepatocytes has been proposed for the temporary metabolic support of patients awaiting liver transplantation or spontaneous reversion of their liver disease. A major limitation of this form of therapy is the present inability to isolate an adequate number of transplantable hepatocytes. A highly differentiated cell line, NKNT-3, was generated by retroviral transfer in normal primary adult human hepatocytes of an immortalizing gene that can be subsequently and completely excised by Cre/Lox site-specific recombination. When transplanted into the spleen of rats under transient immunosuppression, reversibly immortalized NKNT-3 cells provided life-saving metabolic support during acute liver failure induced by 90% hepatectomy.