Guillain-Barré syndrome in a local area in Japan, 2006-2015: an epidemiological and clinical study of 108 patients.

BACKGROUND AND PURPOSE: Many epidemiological studies of Guillain-Barré syndrome (GBS) and Fisher syndrome (FS) have been conducted in Europe and America. In contrast, epidemiological studies are rare in Asia where the GBS subtypes differ from those in Western countries. This study was undertaken to clarify the incidence of GBS and FS in a local area in Japan as well as their seasonal trends. METHOD: Seventy-one GBS and 37 FS patients were recorded from 2006 to 2015 in an area of approximately 1.5 million inhabitants in Japan. The incidence, seasonal trends and clinical features of GBS and FS were examined. RESULTS: The incidence rate of GBS was 0.42 cases per 100 000 person-years and that of FS was 0.22 cases per 100 000 person-years. The incidence of GBS increased with age and FS affected predominantly patients aged from 45 to 64 years old. There was some seasonal clustering of acute motor axonal neuropathy (AMAN) and FS in spring and summer, but it was not significant. AMAN and FS patients had a high frequency of preceding infection (AMAN, 68% gastrointestinal infection; FS, 65% upper respiratory infection). Antecedent respiratory infection was significantly associated with FS as an outcome. Serum antibodies to ganglioside GM1 were detected in 71% of AMAN patients and antibodies to GQ1b were detected in 81% of FS patients. CONCLUSIONS: Our study offers evidence of a lower incidence of GBS and a higher incidence of FS in a local area in Japan than in Western countries.

Intramuscular dissociation of echogenicity in the triceps surae characterizes sporadic inclusion body myositis.

BACKGROUND AND PURPOSE: Differential diagnosis of sporadic inclusion body myositis (s-IBM) and polymyositis (PM)/dermatomyositis (DM) is difficult and can affect proper disease management. Detection of heterogeneous muscular involvement in s-IBM by muscle sonography could be a unique diagnostic feature. METHODS: Sonography of the lower leg and forearm was performed in patients with s-IBM, PM/DM and control subjects (n = 11 each). Echo intensities (EIs) of the adjacent muscles [medial head of the gastrocnemius versus soleus and the flexor digitorum profundus (FDP) versus flexor carpi ulnaris (FCU)] were scored by three blinded raters. The mean EIs of these muscles were compared using computer-assisted histogram analysis. RESULTS: Both evaluation methods showed high echoic signals in the gastrocnemius of patients with s-IBM. EIs were significantly different between the gastrocnemius and soleus in patients with s-IBM, but not in those with DM/PM and the controls. In the forearm, although the EI of the FDP was higher in the s-IBM group than in the other groups, the EI differences between the FDP and FCU did not differ significantly between disease groups. The difference in area under the curves to differentiate between s-IBM and DM/PM was greatest between the gastrocnemius-soleus EIs (0.843; P = 0.006). CONCLUSIONS: High echoic signals in the medial gastrocnemius compared with those of the soleus are suggestive of s-IBM over PM/DM.

Associations of various gene polymorphisms with toxicity in colorectal cancer patients receiving oral uracil and tegafur plus leucovorin: a prospective study.

BACKGROUND: To assess the predictive value of polymorphism in nine genes, primarily thymidylate synthase (TS) and orotate phosphoribosyltransferase (OPRT), which relates to 5-fluorouracil (5-FU) metabolism, for toxicity in patients treated with oral uracil/tegafur (UFT) plus leucovorin (LV). PATIENTS AND METHODS: We treated 99 patients with stage II or III colorectal carcinoma with oral UFT + LV. Germline DNA from patients was genotyped for 5-FU and folate metabolism-relating genes. CYP2A6, tegafur-activating enzyme, and uridine diphosphate-glucuronosyltransferase 1A1 genetic variation were also assessed. Toxicity was graded by the National Cancer Institute Common Toxicity Criteria, version 2.0. RESULTS: The multivariate logistic regression revealed that OPRT 638G>C polymorphism was associated with grade 3 diarrhea [odds ratio (OR) 19.84 for patients with the C/C homozygous type compared with patients with wild type, P = 0.014] and polymorphisms of UGT1A1 were associated with hyperbilirubinemia (OR 38.76 for homozygotes and double heterozygotes of *6 or *28 compared with wild type, P = 0.0008). No relationships were observed between TS polymorphisms and any toxicity. CONCLUSIONS: OPRT polymorphism predicts toxicity, especially grade 3 or greater diarrhea to oral UFT + LV adjuvant chemotherapy, whereas TS does not, in our study cohort. UGT1A1 polymorphism seems to be a risk factor for hyperbilirubinemia due to UFT+LV.

A day trip to a forest park increases human natural killer activity and the expression of anti-cancer proteins in male subjects.

We previously reported that 2-night/3-day trips to forest parks enhanced human NK activity, the number of NK cells, and intracellular anti-cancer proteins in lymphocytes, and that this increased NK activity lasted for more than 7 days after the trip in both male and female subjects. In the present study, we investigated the effect of a day trip to a forest park on human NK activity in male subjects. Twelve healthy male subjects, aged 35-53 years, were selected after giving informed consent. The subjects experienced a day trip to a forest park in the suburbs of Tokyo. They walked for two hours in the morning and afternoon, respectively, in the forest park on Sunday. Blood and urine were sampled in the morning of the following day and 7 days after the trip, and the NK activity, numbers of NK and T cells, and granulysin, perforin, and granzyme A/B-expressing lymphocytes, the concentration of cortisol in blood samples, and the concentration of adrenaline in urine were measured. Similar measurements were made before the trip on a weekend day as the control. Phytoncide concentrations in the forest were measured. The day trip to the forest park significantly increased NK activity and the numbers of CD16(+) and CD56(+) NK cells, perforin, granulysin, and granzyme A/B-expressing NK cells and significantly decreased CD4(+) T cells, the concentrations of cortisol in the blood and adrenaline in urine. The increased NK activity lasted for 7 days after the trip. Phytoncides, such as isoprene, alpha-pinene, and beta-pinene, were detected in the forest air. These findings indicate that the day trip to the forest park also increased the NK activity, number of NK cells, and levels of intracellular anti-cancer proteins, and that this effect lasted for at least 7 days after the trip. Phytoncides released from trees and decreased stress hormone levels may partially contribute to the increased NK activity.

Clinical and endoscopic characteristics of acute haemorrhagic rectal ulcer, and endoscopic haemostatic treatment: a retrospective study of 95 patients.

AIM: Acute haemorrhagic rectal ulcer (AHRU) is characterized by sudden onset of painless and massive rectal bleeding in elderly bedridden patients who have serious illness. Endoscopic diagnosis and management of AHRU is, however, still controversial. We retrospectively investigated 95 AHRU patients to elucidate the clinical characteristics, endoscopic findings and haemostatic strategies. METHOD: Between January 1999 and March 2007, 95 patients were diagnosed with AHRU in our hospital. Medical records and colonoscopy files were reviewed. Clinical features, colonoscopic findings, haemostatic treatment and outcome of the patients were evaluated. RESULTS: Eighty per cent of the patients were bedridden at the onset. The most frequent underlying disorder was cerebrovascular disease (36.8%). Hypoalbuminaemia (< 3.5 g/dl) was seen in 92.6% of the patients. Endoscopic findings of AHRU were classified as circumferential ulcer (41.1%), linear or nearly round small ulcer(s) (44.2%), circumferential and small ulcer(s) (7.4%) and Dieulafoy-like ulcer (7.4%). Primary endoscopic haemostatic treatment was performed in 45.3% of cases. Recurrent bleeding occurred in 24.2% of patients. Permanent haemostasis was achieved by secondary endoscopic treatment in 82.6% of re-bleeding patients. CONCLUSION: Understanding the typical clinical and endoscopic findings and careful endoscopic examination are important for the accurate diagnosis of AHRU, and endoscopic haemostatic therapy may be effective for bleeding patients.

Phase II study of S-1 combined with irinotecan (CPT-11) in patients with advanced colorectal cancer.

OBJECTIVE: To determine the efficacy and tolerability of oral fluoropyrimidine S-1 plus irinotecan in patients with previously untreated advanced colorectal cancer. METHODS: S-1 was administered orally at 80 mg/m(2)/day for 21 consecutive days followed by a 2-week rest. CPT-11 was given intravenously on days 1 and 15 of each course, at a dose of 80 mg/m(2)/day. Courses were repeated every 5 weeks, unless disease progression or severe toxicities were observed. RESULTS: A total of 282 courses of treatment were administered to 40 patients, achieving complete response in 1 and partial responses in 24 with an overall response rate of 62.5% (95% CI: 47.5-77.5%). Median progression-free survival was 7.8 months (95% CI: 6.7-9.6 months). The rates of grade 3 or 4 toxicities were as follows: neutropenia 12.5%, anorexia 12.5%, fatigue 10%, and diarrhea 7.5%. CONCLUSION: Combined treatment with S-1 and irinotecan is an effective, well-tolerated and convenient regimen in patients with advanced colorectal cancer which is easily maintained.

Increasing incidence of elderly onset patients with myasthenia gravis in a local area of Japan.

OBJECTIVE: As the number of elderly patients with myasthenia gravis (MG) has recently increased in Europe and the USA, a retrospective survey of Japanese MG patients was conducted in a single neurological centre over several decades. METHODS: The study consisted of 112 consecutive MG patients with onset of the disease from 1971 to 2006 from an area of approximately 0.8 million inhabitants in Japan. Patients were classified into three subgroups according to age at onset: young onset (39 years old), middle aged onset (40-59 years old) and elderly onset (60 years old). The trends in incidence rate and clinical features were examined: disease severity, seropositivity for antiacetylcholine receptor antibody, occurrence of other autoimmune diseases, occurrence of thymoma and therapeutic response. RESULTS: The onset adjusted age specific average annual incidence per 100,000 of the elderly onset MG patients increased 20-fold from 1981-1990 (0.06; 95% CI 0.00 to 0.36) to 2001-2006 (1.30; 95% CI 0.77 to 2.05). Clinical features of the elderly onset MG patients included low antiacetylcholine receptor antibody titres (mean 24.6 nmol/l), less frequent autoimmune overlaps (8.0%) and nearly no complete stable remission with or without thymectomy. CONCLUSION: The increasing incidence of elderly onset MG in Japanese patients similar to that reported in Caucasians has been confirmed. The clinical features suggest different immunological backgrounds between young onset and elderly onset MG patients, irrespective of the ethnic background.

Visiting a forest, but not a city, increases human natural killer activity and expression of anti-cancer proteins.

We previously reported that a forest bathing trip enhanced human NK activity, number of NK cells, and intracellular anti-cancer proteins in lymphocytes. In the present study, we investigated how long the increased NK activity lasts and compared the effect of a forest bathing trip on NK activity with a trip to places in a city without forests. Twelve healthy male subjects, age 35-56 years, were selected with informed consent. The subjects experienced a three-day/two-night trip to forest fields and to a city, in which activity levels during both trips were matched. On day 1, subjects walked for two hours in the afternoon in a forest field; and on day 2, they walked for two hours in the morning and afternoon, respectively, in two different forest fields; and on day 3, the subjects finished the trip and returned to Tokyo after drawing blood samples and completing the questionnaire. Blood and urine were sampled on the second and third days during the trips, and on days 7 and 30 after the trip, and NK activity, numbers of NK and T cells, and granulysin, perforin, and granzymes A/B-expressing lymphocytes in the blood samples, and the concentration of adrenaline in urine were measured. Similar measurements were made before the trips on a normal working day as the control. Phytoncide concentrations in forest and city air were measured. The forest bathing trip significantly increased NK activity and the numbers of NK, perforin, granulysin, and granzyme A/B-expressing cells and significantly decreased the concentration of adrenaline in urine. The increased NK activity lasted for more than 7 days after the trip. In contrast, a city tourist visit did not increase NK activity, numbers of NK cells, nor the expression of selected intracellular anti-cancer proteins, and did not decrease the concentration of adrenaline in urine. Phytoncides, such as alpha-pinene and beta-pinene were detected in forest air, but almost not in city air. These findings indicate that a forest bathing trip increased NK activity, number of NK cells, and levels of intracellular anti-cancer proteins, and that this effect lasted at least 7 days after the trip. Phytoncides released from trees and decreased stress hormone may partially contribute to the increased NK activity.

Liddle disease caused by a missense mutation of beta subunit of the epithelial sodium channel gene.

Mutations in beta or gamma subunit of the epithelial sodium channel (ENaC) have been found to cause a hereditary form of human hypertension, Liddle syndrome. Most of the mutations reported are either nonsense mutations or frame shift mutations which would truncate the cytoplasmic carboxyl terminus of the beta or gamma subunits of the channel, suggesting that these domains are important for the normal regulation of this channel. We sequenced ENaC in a family with Liddle syndrome and found a missense mutation in beta subunit which predicts substitution of Tyr by His at codon 618, 2 bp downstream from a missense mutation (P616L) that has been reported recently. Presence of this mutation correlates with the clinical manifestations (hypertension, hypokalemia, suppressed aldosterone secretion) in this kindred. Functional expression studies in the Xenopus oocytes revealed constitutive activation of the Y618H mutant indistinguishable from that observed for the deletion mutant (R564stop) identified in the original pedigree of Liddle. Our data suggest that the region between Pro616 and Tyr618 is critically important for regulation of ENaC activity.

Identification of constitutive and gamma-interferon- and interleukin 4-regulated proteins in the human renal carcinoma cell line ACHN.

The effects of IFN-gamma and interleukin 4 (IL-4) on cell proliferation and two-dimensional gel electrophoretic protein patterns of the human renal carcinoma cell line ACHN were studied. Treatment of the cells with IFN-gamma resulted in a 40-50% decrease in their proliferation. IL-4 treatment resulted in a 30-40% decrease. Treating cells with both cytokines had the same effect as with IFN-gamma alone, thus precluding a synergistic antiproliferative interaction of these two cytokines. To identify IL-4- and IFN-gamma-regulated proteins in ACHN, two-dimensional preparative gel electrophoresis was used, combined with either capillary electrophoresis or high-performance liquid chromatography and either Edman or mass spectrometric sequencing. The following cytokine-induced proteins were identified: tropomyosin, heat shock protein 27, manganese superoxide dismutase, glutathione S-transferase pi, and protein kinase C inhibitor I. Tropomyosin increased 2-fold when cells were treated with IFN-gamma. Levels of heat shock protein 27 increased 2-fold with IL-4, 3-fold with IFN-gamma, and 4-fold when the cytokines were used in combination. Manganese superoxide dismutase increased 3-fold with IFN-gamma but was unaffected by IL-4. Glutathione S-transferase pi increased 3-fold with IFN-gamma. Levels of protein kinase C inhibitor I increased greater than 3-fold with IL-4, 4-fold with IFN-gamma, and 7-fold when both cytokines were used. In addition, the following constitutive ACHN proteins were identified: copper zinc superoxide dismutase, 60S acidic ribosomal protein P2, and a second heat shock protein 27 isoform. These findings help define the biochemical modes of action of IFN-gamma and IL-4 and their potential in the biological therapy of renal cell carcinoma.

Establishment of an enzyme immunoassay system for gliostatin/platelet-derived endothelial cell growth factor (PD-ECGF).

A two-site enzyme immunoassay for gliostatin (GLS)/platelet-derived endothelial cell growth factor (PD-ECGF) has been developed. The detection limit of gliostatin/PD-ECGF was 30 pg/well, and the optimal assay range was 0.1 to ng/well. This assay system enabled us to confirm the immunochemical identity of both factors and to detect immunoreactive gliostatin/PD-ECGF (IR-GLS/PD-ECGF) in human biological body fluids. The age-related analysis from newborn to 69 years revealed that the serum IR-GLS/PD-ECGF level was high in infants younger than 1 year old (1.8 ng/ml) and in the 20-year-old age group (1.8 ng/ml), and highest in the umbilical cord blood (2.1 ng/ml). Curiously high concentrations were detected in saliva with a significant sex difference (11.3 ng/ml for males and 48.7 ng/ml for females), and in synovial fluids (3.7 ng/ml). A number of human tumor cells, gastric cancer cells, MKN-74, neuroblastoma cells, GOTO, as well as epidermoid carcinoma cells, A431, were found to produce a significant amount of IR-GLS/PD-ECGF (0.2 to 21.8 ng/mg protein), and some of them secreted the IR-GLS/PD-ECGF in the conditioned medium (approximately 0.5 ng/ml). The enzyme immunoassay system is sufficiently sensitive for the basic and clinical study of gliostatin/PD-ECGF in human body fluids, tissues and organs.

Mechanism of prostaglandin D(2)-stimulated heat shock protein 27 induction in osteoblasts.

We previously showed that prostaglandin D(2) (PGD(2)) stimulates activation of protein kinase C (PKC). We investigated whether PGD(2) stimulates the induction of heat shock protein (HSP) 27 and HSP70 in osteoblast-like MC3T3-E1 cells and the mechanism underlying the induction. PGD(2) increased the levels of HSP27 while having little effect on HSP70 levels. PGD(2) stimulated the accumulation of HSP27 dose dependently in the range between 10 nM and 10 microM. PGD(2) induced an increase in the levels of mRNA for HSP27. The PGD(2)-stimulated accumulation of HSP27 was reduced by staurosporine or calphostin C, inhibitors of PKC. PGD(2) induced the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase. The HSP27 accumulation induced by PGD(2) was significantly suppressed by PD98059, an inhibitor of the upstream kinase of p44/p42 MAP kinase, or SB203580, an inhibitor of p38 MAP kinase. Calphostin C suppressed the PGD(2)-induced phosphorylation of p44/p42 MAP kinase and p38 MAP kinase. PD98059 or SB203580 suppressed the PGD(2)-increased levels of mRNA for HSP27. These results strongly suggest that PGD(2) stimulates HSP27 induction through p44/p42 MAP kinase activation and p38 MAP kinase activation in osteoblasts and that PKC acts at a point upstream from both the MAP kinases.

Cloning of a complementary deoxyribonucleic acid coding for human thyroxine-binding globulin (TBG): existence of two TBG messenger ribonucleic acid species possessing different 3'-untranslated regions.

An adult human liver cDNA library constructed in expression vector, bacteriophage lambda gt11, was screened with polyclonal antibody directed against human T4-binding globulin (TBG). TBG cDNA cloned in the present study was 944 nucleotides in length. It contained approximately 70% of the coding region and complete 3'-untranslated region. When the sequence was compared with that of TBG cDNA recently cloned by I. L. Flint, T. J. Bailey, T. A., Gustafson, B. E. Markham, and E. Morkin, the 3'-untranslated region of our cDNA was 231 nucleotides shorter than their cDNA. These results indicated that two TBG mRNAs with different length of 3'-untranslated regions may exist in human liver. Indeed, Northern blot analysis revealed that two TBG mRNAs differing in the length approximately 200 base pairs were present in normal human liver as well as in human hepatoma cell line (HepG2). It was demonstrated that this size difference was due to the length of 3'-untranslated region by hybridization with a probe specific to the longer 3'-end. Together with the sequence data, it was suggested that these two TBG mRNA species may be produced by alternative processing and polyadenylation at two different sites.

An additional carbohydrate chain in the variant thyroxine-binding globulin-Gary (TBGAsn-96) impairs its secretion.

The T4-binding globulin-Gary (TBG-G) variant has severely impaired T4 binding, is unstable at 37 C, and presents an apparent anodal shift of all isoforms when submitted to isoelectric focusing. Inheritance of this abnormal TBG produces a profound decrease in the serum levels of native TBG with reciprocal changes in its denatured form, causing thyroid hormone concentrations to be as low as those found in complete TBG deficiency. The TBG-G gene possesses a single nucleotide substitution replacing the normal IIe96 (ATC) with Asn (AAC), thus creating a new site for N-linked glycosylation. In order to determine whether TBG-G contains an additional carbohydrate chain as indirectly suggested by the isoelectric focusing results, cDNAs containing the normal TBG (TBG-N), and TBG-G were inserted in the appropriate vectors to allow their expression in mammalian cells (COS-1) and in amphibian (Xenopus) oocytes. In both systems, expression of TBG-G yielded a larger molecule than TBG-N when analyzed by polyacrylamide gel electrophoresis under denaturing conditions. However, both were identical in size when synthesized in COS-1 cells in the presence of tunicamycin or when deglycosylated after their synthesis in Xenopus oocytes. Pulse chase experiments revealed impaired secretion and excessive overall intracellular degradation of TBG-G relative to TBG-N. As expected from studies on serum from affected subjects, in vitro expressed TBG-G had a 10-fold lower affinity for T4. These studies prove that the new site for potential glycosylation created by the point mutation in TBG-G is indeed glycosylated.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of low density lipoprotein receptor gene in human placenta during pregnancy.

Mammalian cells require cholesterol as a structural component of plasma membranes. It is also required for placental steroid synthesis. De novo synthesis of cholesterol is limited in human placenta and cholesterol is obtained mainly from plasma low density lipoprotein (LDL). Cholesterol delivery from LDL is mediated by receptor-mediated uptake and the receptor amount is the most important factor for cellular delivery. Thus, the regulation of receptor synthesis is important for placental development and function. Since the regulation of LDL receptor gene expression has not been studied in human placenta, LDL receptor mRNA was measured in placentae of 5-40 weeks of gestation by hybridization of RNA with 32P-labeled cDNA for human LDL receptor. Two mRNA species for LDL receptor were demonstrated by Northern blot analysis. The longer mRNA [5.3 kilobases (kb)] was much more abundant than the shorter mRNA (3.7 kb). The amount of 5.3 kb mRNA was highest early in gestation and decreased during pregnancy. However, the amount of 3.7 kb mRNA did not change appreciably during gestation. Dot blot analysis of 26 placental mRNAs obtained from various stages of gestation revealed a negative correlation between LDL receptor mRNA and gestation (r = -0.76, P less than 0.001). Considering the rapid growth of the trophoblast during gestation, especially in the first and the second trimester, increased expression of the LDL receptor gene and subsequent translation are expected for efficient cholesterol uptake to provide a sufficient substrate for cell growth. Possible mechanisms for the appearance of two mRNA species for LDL receptor are also discussed.

Specific induction of fibronectin gene in rat liver by thyroid hormone.

The regulation of fibronectin (FN) gene expression by thyroid hormone was studied. Rats were rendered hypothyroid by thyroidectomy, and the administration of T4 or T3 was used to produce rats in various thyroid states. RNA was extracted from fresh liver, kidney, and heart, and FN mRNA was determined by dot blot hybridization with a 32P-labeled rat FN cDNA probe. The specificity of the hybridization was assessed by Northern blot analysis. In liver, thyroidectomy decreased the abundance of FN mRNA by half, and daily administration of physiological doses of T4 or T3 for 5-6 days restored FN mRNA to the control level. The administration of pharmacological doses of thyroid hormones induced a further increase in the abundance of FN mRNA. A significant dose-dependent correlation between serum levels of T4 and the abundance of FN mRNA was observed in liver. A receptor-saturating dose of T3 (200 micrograms) given to thyroidectomized rats produced a significant increase in FN mRNA within 6 h after injection, indicating that expression of the FN gene was induced relatively rapidly. Moreover, a nuclear run-off assay revealed that thyroid hormone induces expression of the FN gene at least in part at a transcriptional level. The amount of FN mRNA was also determined in kidney and heart of the same rats. Although the abundance of FN mRNA changed by thyroidectomy or the administration of thyroid hormone in those organs, the magnitude of changes were slight compared with those observed in liver. These results suggested that a marked and dose-dependent induction of the FN gene by thyroid hormone occurs specifically in liver.(ABSTRACT TRUNCATED AT 250 WORDS)

A novel stromal cell-dependent hematopoietic cell line established from temperature-sensitive SV40 T-antigen transgenic mice.

A novel primitive hematopoietic cell line, THS119, was established from lineage marker negative (Lin-)/Sca-1+ cells from bone marrow of temperature-sensitive (ts) SV40 T-antigen transgenic mice after lengthy passaging by coculture with TBR59 bone marrow stromal cells. THS119 cells exhibited immature primitive hematopoietic cells such as forming cobblestones underneath the stromal cell layers. They retained properties of hematopoietic stem cells as shown by expression of c-Kit, Sca-1 and CD34low, but lacked hematopoietic lineage surface markers of differentiated hematopoietic cells (Gr-1, TER119, Mac-1, CD3, B220). RT-PCR analysis showed that THS119 cells exhibited multiple expression of both earlier developmental markers of myeloid, lymphoid and the hematopoietic cell specific transcription factors. THS119 cells showed temperature-dependent growth reflecting ts T-antigen, and their maintenance was TBR59 stromal cell-dependent. The requirement of stromal cells could not be replaced by cytokines, however, an IL-3 or IL-7 dependent cell line was generated after prolonged culture of THS119 cells on the stromal cells in the presence of these cytokines, and these cytokine-dependent cell lines exhibited phenotypes similar to the parental cells in their gene expression. SCF/c-Kit interaction is one factor required for their maintenance, but involvement of other factor(s) in the conditioned medium of TBR59 stromal cells was suggested. A novel immature hematopoietic cell line, THS119, may provide an appropriate experimental system to resolve how hematopoietic cells are kept in a primitive phase within a hematopoietic microenvironment.

Osteoblasts express types I and II activin receptors during early intramembranous and endochondral bone formation.

Increasing evidence suggests a potential role for activin in bone formation. However, the cognate receptors through which activins function with respect to skeletal tissues have not yet been identified. Identification and regulation of expression of these receptors are necessary prerequisites to understanding the role of activins in bone metabolism. We detected mRNAs for three activin receptors, type I (ActRI), type II (ActRII), and type IIB (ActRIIB), in multiple skeletal tissues in rat, including tibia and costochondral growth plate, and also in cultured osteoblasts. To gain information about the relationship between receptor expression and different skeletal cell functions, we evaluated expression of the three receptors in a semiquantitative manner during the early stages of fracture healing, a model for rapid bone formation. Relatively high levels of ActRI and ActRII expression were detected in the callus at 7, 10, and 14 days after fracture, times that correlate with the interval of rapid intramembranous bone formation and the initiation of endochondral bone formation. Expression of the ActRIIB in the fracture callus was strikingly lower than either ActRI or ActRII. Immunostaining of the fracture callus and the newborn rat femur with an anti-ActRII antibody localized the receptor to osteoblasts at regions of membranous and endochondral bone formation. No staining of osteoblasts in fracture callus or bone was seen with an anti-ActRIIB antibody. These results provide strong evidence of the identification of the principal receptors through which activins could function in the skeletal system and further shed light on activin's mechanism of action in bone formation.