Radiation-inducible hSNK gene is transcriptionally regulated by p53 binding homology element in human thyroid cells

We identified a species relevant to polo-like kinase family, a human homologue of mouse serum-inducible kinase, hSNK gene, whose mRNA expression was rapidly increased in cultured human thyroid cells after X-ray irradiation. The cDNA cloning and genomic analysis of the hSNK gene showed the presence of 14 exons spanning over 6 kb of genomic DNA that encodes a 2.9-kb mRNA product. Promoter analysis demonstrated possible existence of a radiation-responsive element in the p53 binding homology element (p53RE) localized to near upstream of basal promoter of the hSNK gene. Nuclear protein extracts from HeLa and various human thyroid carcinoma cell lines bound selectively to p53RE. Anti-p53 or anti-p73 antibodies, however, failed to recognize the p53RE-protein complex formed in the presence of such nuclear extracts. These results suggest that radiation-responsive transcription factor(s) directly participates in the regulation of hSNK gene expression via the binding to p53RE in promoter region.

Kinetic analysis of [(11)C]MP4A using a high-radioactivity brain region that represents an integrated input function for measurement of cerebral acetylcholinesterase activity without arterial blood sampling

N -[(11)C]methylpiperidin-4-yl acetate ([(11)C]MP4A) is an acetylcholine analog. It has been used successfully for the quantitative measurement of acetylcholinesterase (AChE) activity in the human brain with positron emission tomography (PET). [(11)C]MP4A is specifically hydrolyzed by AChE in the brain to a hydrophilic metabolite, which is irreversibly trapped locally in the brain. The authors propose a new method of kinetic analysis of brain AChE activity by PET without arterial blood sampling, that is, reference tissue-based linear least squares (RLS) analysis. In this method, cerebellum or striatum is used as a reference tissue. These regions, because of their high AChE activity, act as a biologic integrator of plasma input function during PET scanning, when regional metabolic rates of [(11)C]MP4A through AChE (k(3); an AChE index) are calculated by using Blomqvist's linear least squares analysis. Computer simulation studies showed that RLS analysis yielded k(3) with almost the same accuracy as the standard nonlinear least squares (NLS) analysis in brain regions with low (such as neocortex and hippocampus) and moderately high (thalamus) k(3) values. The authors then applied these methods to [(11) C]MP4A PET data in 12 healthy subjects and 26 patients with Alzheimer disease (AD) using the cerebellum as the reference region. There was a highly significant linear correlation in regional k(3) estimates between RLS and NLS analyses (456 cerebral regions, [RLS k(3) ] = 0.98 x [NLS k(3) ], r = 0.92, P < 0.001). Significant reductions were observed in k(3) estimates of frontal, temporal, parietal, occipital, and sensorimotor cerebral neocortices (P < 0.001, single-tailed t-test), and hippocampus (P = 0.012) in patients with AD as compared with controls when using RLS analysis. Mean reductions (19.6%) in these 6 regions by RLS were almost the same as those by NLS analysis (20.5%). The sensitivity of RLS analysis for detecting cortical regions with abnormally low k 3 in the 26 patients with AD (138 of 312 regions, 44%) was somewhat less than NLS analysis (52%), but was greater than shape analysis (33%), another method of [(11)C]MP4A kinetic analysis without blood sampling. The authors conclude that RLS analysis is practical and useful for routine analysis of clinical [(11)C]MP4A studies.

Urinary iodine levels and thyroid diseases in children; comparison between Nagasaki and Chernobyl

We evaluated the incidence of childhood thyroid diseases and urinary iodine levels in Nagasaki, Japan and in Gomel, Belarus, which was greatly radio-contaminated by the Chernobyl accident, in order to obtain the comparative data of thyroid diseases between iodine-rich (Japan) and -deficient (Belarus) areas. In Nagasaki, the median level of urinary iodine, measured by ammonium persulfate digestion in microplate method, was 362.9 microg/L. In order to evaluate the geographical differences in Japan, other samples were collected in Hamamatsu and in South Kayabe, Hokkaido, where the median levels were 208.4 microg/L and 1015.5 microg/L, respectively. Furthermore, thyroid screening by ultrasound (US) in Nagasaki revealed only four cases that showed goiter (1.6%) and two cases (0.8%) that had cystic degeneration and single thyroid cyst. There was no evidence of thyroid nodule detected by US examination. In contrast, the median of urinary iodine level was 41.3 microg/L in Gomel. The incidences of goiter (13.6%) and echogenic abnormality (1.74%) in Gomel were much higher than in Nagasaki, suggesting the critical involvement of iodine deficiency in increased childhood thyroid abnormality around Chernobyl. Radioactive iodine released just after the Chernobyl accident may have influenced predominantly children residing in iodine-deficient areas. Our results suggest that management of thyroid screening for schoolchildren at ordinary times may be beneficial for monitoring the adverse effects of radioactive iodine from the standpoint of future prospective study.

Coexistence of thyrotropin-producing pituitary adenoma with papillary adenocarcinoma of the thyroid--a case report and surgical strategy

We report a very rare case of thyrotropin (thyroxin stimulating hormone, TSH)-producing pituitary adenoma coexisting with a papillary adenocarcinoma of the thyroid. A 45-year-old woman presented with hyperhidrosis and a nodule in the left thyroid that was first noticed one year earlier. An endocrinological examination showed elevated serum levels of free triiodothyronine (T3) and free throxin (T4) without inhibition of TSH, suggesting the presence of syndromes of inappropriate secretion of TSH. A specimen obtained by needle aspiration of the thyroid nodule revealed the presence of papillary adenocarcinoma. Magnetic resonance images demonstrated a pituitary macroadenoma. The patient was diagnosed as having a TSH-producing pituitary adenoma coexisting with a papillary adenocarcinoma of the thyroid. The patient underwent a total thyroidectomy with resection of the neighboring lymph nodes. Two weeks after this surgery, the pituitary adenoma was totally removed via a pterional approach. Histological and immunohistochemical examinations of the surgical specimens confirmed the lesion as a papillary adenocarcinoma of the thyroid and a TSH-producing pituitary adenoma. Serum TSH levels decreased to undetectable levels immediately after the surgery for the pituitary adenoma. Prolonged stimulation of the thyroid gland by TSH may be involved in the growth of thyroid carcinoma. In cases with a TSH-producing pituitary adenoma, the possible coexistence of thyroid carcinoma should be carefully ruled out. In such cases, a total thyroidectomy followed by TSH level normalization should be performed. Incomplete removal of the thyroid might enable the carcinoma to re-grow if TSH level can not be normalized after the pituitary adenomectomy.

Cdc6 expression as a marker of proliferative activity in brain tumors

Antibodies against human proteins that regulate DNA replication such as Cdc6 and Mcm5 became available as a new marker of proliferation. We performed immunohistochemical analysis with MIB-1 and antibody against Cdc6 on 35 brain tumors, including tumors of neuroepithelial tissue, vestibular schwannomas, meningiomas, and pituitary adenomas. Median reactivity for MIB-1 was 8.8%, and that for Cdc6 was 55%. Reactivity in most brain tumors was significantly higher for Cdc6 than for MIB-1, but reactivity of Cdc6 was independent of tumor grade. Detection of Cdc6 expression might be useful for the estimation of proliferative activity in brain tumors.

Transient activation of c-Jun NH2-terminal kinase by growth factors influences survival but not apoptosis of human thyrocytes

Activation of c-Jun NH2-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family, is involved in apoptosis or cell proliferation. We have previously demonstrated that ionizing radiation or thyroid-stimulating hormone activated JNK without linking to thyroid cell apoptosis. To clarify the involvement of JNK activation in thyroid cell survival, we investigated the effects of various growth factors on induction of JNK activation in cultured human thyroid cells. JNK activation was observed at 30 minutes after fetal bovine serum (FBS) stimulation and returned to basal level at 240 minutes. Epidermal growth factor (EGF), transforming growth factor-beta (TGF-beta) and hepatocyte growth factor (HGF) also induced JNK activation, but did not trigger apoptotic cell death. Furthermore, we observed high basal activation of JNK in four of five human thyroid cancer cell lines. Overexpression of c-Met, an HGF receptor, was observed in two of the four cell lines with high basal JNK activity. Our results suggest that JNK activation does not induce apoptosis but is associated with survival or transformation of human thyroid cells.

Involvement of wild-type p53 in radiation-induced c-Jun N-terminal kinase activation in human thyroid cells

c-jun-N-terminal kinases (JNKs) play an important role in defense against external stresses including ionizing radiation (IR). We have previously shown that sensitivity to IR is influenced by p53 status in human thyroid cells. In this study, we investigated the effect of p53 status on IR-induced JNK activation in human thyroid cells. Our results showed high basal JNK activity in the p53-null thyroid cancer cell line, FRO. In contrast, primary cultured thyroid cells (PT), which harbor wild-type p53, had low basal JNK activity. IR increased JNK activity in PT, however, no such increase was noted in FRO cells. Introduction of the wild-type p53 into FRO cells reduced JNK activity to a low basal level and rendered it responsive to IR. There was no difference in IR-induced ceramide production between PT and FRO cells. Our results provide clear evidence that p53 status influences, directly or indirectly, radiation-induced JNK activation in human thyroid cells, suggesting that a feedback or interaction pathway between p53 and JNK regulates radiation-induced cell fate.

Sage transcript profiles in cultured human fetal fibroblasts, WI-38

Serial analysis of gene expression (SAGE) allows us to analyze the profile of genes expressed in human lung fibroblast cell line WI-38. Manual sequencing of approximately 10,000 transcripts derived from WI-38 cells revealed 1025 genes expression among of which 431 tags matched GenBank entries, whereas 594 corresponded to novel previously undescribed transcripts. 7SL RNA (7L7) 5'-truncated pseudogene and the gene with no match (tag: TCCCTAGCT) were found the most abundant among all the analyzed genes (10.2 and 4.6% respectively). The expression pattern of the genes coding for cytoskeletal proteins, extracellular matrix components (ECM) and cytokines has been obtained. The results here demonstrate the unique gene expression pattern in human WI-38 fibroblast cell line and support a possibility of useful application of SAGE method for differential expression analysis.

Efficacy of the bystander effect in the herpes simplex virus thymidine kinase-mediated gene therapy is influenced by the expression of connexin43 in the target cells

Tumoricidal "bystander effect" observed in the herpes simplex virus thymidine kinase (HSVtk)/ganciclovir (GCV) gene therapy was studied between different rat glioma cell lines (9L and C6 cells) under both in vitro and in vivo conditions. For that purpose, mixed populations of wild-type cells (9Lwt and C6wt) and respective HSVtk gene-transduced cells (9Ltk and C6tk) were examined for their sensitivity to GCV. A potent in vitro bystander effect was observed in 9Lwt/9Ltk and 9Lwt/C6tk combinations but not in C6wt/9Ltk and C6wt/C6tk combinations. In vivo bystander effect studied in a subcutaneous tumor model in athymic nude mice was also potent in 9Lwt/9Ltk and 9Lwt/C6tk combinations. Because the expression of connexin43, a major protein in the connexin family gene products, in 9L cells is much higher than that in C6 cells, the results suggest that the amount of connexin in target (wild-type) cells but not in effector (HSVtk gene-bearing) cells is important for the generation of the bystander effect. This hypothesis was further confirmed by the observation that in vitro bystander effect in C6wt/C6tk combination was potentiated by transduction of the connexin43 gene to the target cells.

Positron emission tomographic measurement of brain acetylcholinesterase activity using N-[(11)C]methylpiperidin-4-yl acetate without arterial blood sampling: methodology of shape analysis and its diagnostic power for Alzheimer's disease

N-[11C]methylpiperidin-4-yl acetate ([11C]MP4A) is a radiotracer that has been used successfully for the quantitative measurement of acetylcholinesterase (AChE) activity in the human brain with positron emission tomography (PET) using a standard compartment model analysis and a metabolite-corrected arterial input function. In the current study, the authors evaluated the applicability of a simple kinetic analysis without blood sampling, namely shape analysis. First, the authors used computer simulations to analyze factors that affect the precision and bias of shape analysis, then optimized the shape analysis procedure for [11C]MP4A. Before shape analysis execution, the later part of dynamic PET data except for the initial 3 minutes were smoothed by fitting to a bi-exponential function followed by linear interpolation of 8 data points between each of adjacent scan frames. Simulations showed that shape analysis yielded estimates of regional metabolic rates of [11C]MP4A by AChE (k3) with acceptable precision and bias in brain regions with low k3 values such as neocortex. Estimates in regions with higher k3 values became progressively more inaccurate. The authors then applied the method to [11C]MP4A PET data in 10 healthy subjects and 20 patients with Alzheimer's disease (AD). There was a highly significant linear correlation in regional k3 estimates between shape and compartment analyses (300 neocortical regions, [shape k3] = 0.93 x [NLS k3], r = 0.89, P < 0.001). Significant reductions in k3 estimates of frontal, temporal, parietal, occipital, and sensorimotor cerebral cortices in patients with AD as compared with controls were observed when using shape analysis (P < 0.013, two-tailed t-test), although these reductions (17% to 20%) were somewhat less than those obtained by compartment analysis (22% to 27%). The sensitivity of shape analysis for detecting neocortical regions with abnormally low k3 in the 20 patients with AD (92 out of 200 regions, 46%) also was somewhat less than compartment analysis (136 out of 200 regions, 68%). However, taking its simplicity and noninvasiveness into account, the authors conclude that quantitative measurement of neocortical AChE activity with shape analysis and [11C]MP4A PET is practical and useful for clinical diagnosis of AD.

PKC delta mediates ionizing radiation-induced activation of c-Jun NH(2)-terminal kinase through MKK7 in human thyroid cells

The thyroid gland is one of the most sensitive organs in ionizing radiation (IR)-induced carcinogenesis. To determine, therefore, the specific cascade of IR-induced signal transduction in human thyroid cells, we investigated the functional role of protein kinase C (PKC), especially its interlocking activation of c-Jun NH(2)-terminal kinase (JNK) pathway. In the present study, using adenovirus expression vectors for diverse dominant-negative (DN) types of PKC isoforms (alpha, beta2, delta, epsilon and zeta) expressed in primary cultured human thyroid cells, only DN/PKC delta suppressed IR-induced JNK activation. In addition, Rottlerin, a PKC delta specific inhibitor, inhibited IR-induced JNK activation. IR-induced activation of transcription factor AP-1, downstream target of JNK, was also attenuated by DN/PKC delta. To examine the involvement of upstream kinases of JNK, we performed immune-complex kinase assays of mitogen-activated protein kinase kinase 4 (MKK4) and MKK7. IR activated MKK7 but not MKK4, and this activation was inhibited by Rottlerin. Furthermore, IR-induced JNK activation was suppressed by overexpression of kinase-deficient MKK7. Our results indicate that IR selectively activates the cascade of PKC delta-MKK7-JNK-AP-1 in human thyroid cells, suggesting a not apoptotic but radio-resistant role of PKC delta in human thyroid cells following IR.

Bystander effect in uracil phosphoribosyltransferase/5-fluorouracil-mediated suicide gene therapy is correlated with the level of intercellular communication

We examined whether a suicide gene/prodrug system using the uracil phosphoribosyltransferase (UPRT) of E. coli origin and 5-fluorouracil (5-FU) could achieve a bystander effect in two rodent tumor cell lines, murine colon carcinoma (Colon 26) and rat gliosarcoma (9L) cells. Cytotoxicity tests of mixed populations consisting of parent and transduced cells showed that the bystander effect was not produced in Colon 26 cells in either the UPRT/5-FU system or the herpes simplex virus-thymidine kinase/ganciclovir system but a strong bystander effect was evidenced by both suicide gene systems in 9L cells. The expression level of connexin 43, a protein that constitutes gap junctions, was high in 9L but low in Colon 26 cells. A gap junction-permeable fluorescein dye could be transferred among 9L cells but hardly at all among Colon 26 cells. Taken together, the efficacy of the bystander effect in the UPRT/5-FU system can be affected by gap junction-mediated intercellular communication.

Targeting the replication of adenovirus to p53-defective thyroid carcinoma with a p53-regulated Cre/loxP system

In this article, we evaluated the feasibility of the restricted replication-competent adenoviruses for treatment of anaplastic thyroid carcinomas (ATCs), which are very aggressive and difficult to treat. Because ATCs very often harbor p53 mutations, we used wt-p53 as a regulatory factor to restrict virus replication and cytopathic effect to p53-mutated cells. The recently reported "gene inactivation strategy" using p53-regulated Cre/loxP system was employed; this system consists of two recombinant adenoviruses. One has an expression unit of the synthetic p53 - responsive promoter and the Cre recombinase gene (Axyp53RECre), and another contains two expression units; the first consists of E1A gene flanked by a pair of loxP sites downstream of the constitutive CAG promoter and the second E1B19K gene under the control of the CMV promoter (AdCALE1AL). We expected that coinfection of these two adenoviruses into the cells with wt-p53 would lead to expression of the Cre, which excises E1A gene and switches off E1A expression resulting in no virus replication, whereas in the cells with mutant p53 E1A could be expressed that leads to virus replication and cell lysis. Our in vitro data demonstrate that although infection of AdCALE1AL alone led to E1A expression, viral replication and cytolysis in all the thyroid cells examined irrespective of their p53 status, the double infection did so in FRO cells (p53-null ATC) but not in FRO cells stably expressing wt-p53 and normal thyroid cells with wt-p53. These data indicate that our double infection method may have a potential for treatment of ATC and probably also other p53-defective cancer cells.

Identification of differentially expressed genes in rat hippocampus after transient global cerebral ischemia using subtractive cDNA cloning based on polymerase chain reaction

BACKGROUND AND PURPOSE

The purpose of this study is to identify new molecules that play important roles in the phenomena that occur in the hippocampus after transient global cerebral ischemia, as clues to better understanding of the mechanisms.

METHODS

A subtractive cDNA library was established by suppression subtractive hybridization of rat hippocampal tissues after transient global cerebral ischemia. With differential screening of the library, upregulated fragments were identified. The mRNA expression levels of selected genes were measured with semiquantitative reverse transcriptase polymerase chain reaction (PCR).

RESULTS

Among more than 100 isolated fragments, approximately half were determined to be identical to known sequences. The rest showed high homology to known sequences, and only 2 did not exhibit homology to any known sequences. The expression of 5 genes identified in this study increased in 24 hours after ischemia to a level twice as high as that in sham-operated controls. These included furin, prosaposin, synaptotagmin IV, heat shock protein 105, and the neutral and basic amino acid transporter (NBAT). The increases in the mRNA expression levels of the genes except NBAT, as revealed by semiquantitative reverse transcription PCR, were statistically significant at both 6 and 24 hours after ischemia.

CONCLUSIONS

Genes isolated are thought to be associated with production of proteins necessary for degeneration, neuroprotection, and reconstruction of neurons. How the expression of these genes relates to functional changes after ischemia remains to be determined. PCR-based subtractive cDNA cloning is demonstrated to be a useful tool for analyzing in vivo gene expression in animal ischemia models.

Keloid fibroblasts resist ceramide-induced apoptosis by overexpression of insulin-like growth factor I receptor

Keloids are benign dermal tumors, characterized by overgrowth of lesions, invasiveness beyond the original boundary of the insult, and recurrence of lesions. The exact etiology is unknown, however. Our hypothesis is that keloids are acquired as a result of an abnormal or prolonged wound healing process, with persistent proliferation and extracellular matrix production of fibroblasts that should otherwise discontinue in normal wound healing. In this study, we examined the response of keloid fibroblasts to proapoptotic signaling. Cell-permeable ceramide, N-acetyl-D-sphingosine, induced apoptosis of dermal fibroblasts in a dose- and time-dependent manner, which was detected by phase contrast microscopy, fluorescent microscopy, the TUNEL method, flow cytometric analysis, and WST-1 assay. In contrast, keloid fibroblasts resisted apoptosis induced by N-acetyl-D-sphingosine (percent survival with 40 mM ceramide treatment for 12 h, normal versus keloid: 9.6% +/- 6.6% vs 66.8% +/- 5.5%). Western blotting analysis showed insulin-like growth factor I receptor overexpression in keloid fibroblasts, but not in normal fibroblasts. Exogenously added insulin-like growth factor I enhanced the resistance of keloid fibroblasts to ceramide-induced apoptosis. Wort- mannin, a phosphatidylinositol 3 kinase inhibitor, suppressed the antiapoptotic action of insulin-like growth factor I in keloid fibroblasts. Our results suggest that keloid fibroblasts overexpressing insulin-like growth factor I receptor are resistant to apoptosis, thus allowing persistent proliferation and production of excessive extracellular matrix. J Invest Dermatol 115:1065-1071 2000

Adenovirus-mediated tumor suppressor p53 gene therapy for anaplastic thyroid carcinoma in vitro and in vivo

The present study was designed to evaluate the therapeutic efficacy of adenovirus-mediated wild-type (wt) tumor suppressor p53 expression in four human thyroid carcinoma cell lines harboring p53 mutations (ARO, FRO, NPA, and WRO) and normal human thyroid follicular cells with wt-p53 in vitro and in vivo. In vitro infection of replication-deficient recombinant adenovirus vector expressing wt-p53 led to a dose-dependent cell killing in both normal and carcinoma cells. In contrast, adenovirus expressing Escherichia coli beta-galactosidase showed little effect. The sensitivity to p53-mediated cell killing varied among the cells used. It was, at least partly, dependent on their adenovirus infectivity in carcinoma cells, whereas normal thyroid cells were relatively resistant to p53-mediated cell death despite its highest adenovirus infectivity. The mechanism of cell killing by wt-p53 was shown, by flow cytometric analysis, to be apoptosis. Furthermore, wt-p53 expression renders two out of four carcinoma cell lines (FRO and NPA) more sensitive to doxorubicin and one (FRO) to 5-fluorouracil, independent of treatment schedule. In vivo experiments, using FRO and NPA cells, showed that growth of sc tumors in nude mice was nearly completely inhibited by direct injection of adenovirus expressing wt-p53 [1 x 10(9) plaque-forming units/tumor]. This effect was augmented by its combination with doxorubicin treatment (4 mg/kg, thrice a week), which led to tumor regression. Our results therefore indicate that adenovirus-mediated wt-p53 gene introduction seems to be a potential clinical utility in gene therapy for anaplastic thyroid carcinomas, particularly when combined with chemotherapy.

Brain acetylcholinesterase activity in Alzheimer disease measured by positron emission tomography

Brain acetylcholinesterase activity was measured in 14 patients with Alzheimer disease and 14 age-matched control subjects by positron emission tomography with a radioactive acetylcholine analogue. Kinetic analysis was performed to calculate k3, an index of acetylcholinesterase activity. The k3 values were significantly reduced in the neocortex, hippocampus, and amygdala of all patients with Alzheimer disease, suggesting a loss of cholinergic innervation from the basal forebrain. Most profound reductions of k3 values were observed in the temporal (-30%) and parietal cortices (-31%), although reductions of k3 values were relatively uniform in the cerebral neocortex. This technique may be a powerful tool for early diagnosis of Alzheimer disease and also for therapeutic monitoring of acetylcholinesterase inhibitors in Alzheimer disease.

[Neurosurgical treatment for dopamine-induced dyskinesias in Parkinson's disease patients]

The effects of current neurosurgical interventions for levodopa-induced dyskiensias (DID) in Parkinson's disease are reviewed. Thalamotomy has been reported to be effective for DID when the lesions include Vo or CM-Pf nucleus, while thalamic deep brain stimulation(DBS) is less effective than thalamotomy. Both pallidotomy and pallidal DBS are probably the most effective neurosurgical treatment for DID, because they significantly improve all of the DID, including off-period dystonia, without reduction of levodopa dosage. Subthalamic DBS has no direct therapeutic effects on DID, but substantially can improve DID as a result of decreased levodopa dosage. The effects of cerebral transplantation on DID remain undefined. More researches are expected to clarify the pathophysiology of DID.

Identification of the sites of asparagine-linked glycosylation on the human thyrotropin receptor and studies on their role in receptor function and expression

The amino-terminal ectodomain of human thyrotropin receptor (TSHR) contains six potential N-linked glycosylation sites (N-Xaa-S/T). This study was designed to evaluate the functional role of TSHR carbohydrates in detail. Because our previous mutagenesis study by Asn to Gln substitutions suggested the critical role of the first and third glycosylation sites (amino acids 77 and 113) for expression of the functional TSHR, we first constructed TSHR mutants having these two glycosylation sites to elucidate whether these two sites are sufficient for TSHR function and expression; this mutant however proved to be nonfunctional. Also the expression levels and function of TSHR mutants with a Ser/Thr to Ala substitution at the first or third glycosylation site were found to be intact. These data indicate that our previous data appear to result from amino acid substitution itself, not from disruption of glycosylation. The next series of the mutants was therefore constructed to identify at least how many glycosylation sites are necessary. Neither TSH binding nor cAMP response was detected in TSHR mutants with three glycosylation sites. However, the mutants with four glycosylation sites were fully functional in terms of TSH binding and cAMP production, although the expression levels were 30 to 40% of that in wild-type TSHR. Finally, Western blot revealed that all six glycosylation sites are actually glycosylated. These data indicate that 1) TSHR ectodomain contains six N-linked carbohydrates, and 2) glycosylation of at least four sites appears necessary for expression of the functional TSHR.

Immunological responsiveness to interleukin-2-producing brain tumors can be restored by concurrent subcutaneous transplantation of the same tumors

The central nervous system shows tolerance for activated host immune reactions, and this relative unresponsiveness may lessen the efficacy of an immunotherapy for brain tumors. Using interleukin-2 (IL-2)-producing 9L rat gliosarcoma cells (9L/IL-2), we examined whether secretion of IL-2 from subcutaneous (s.c.) and/or intracerebral (i.c.) tumors can elicit augmented immunological responses to brain tumors. Syngeneic rats could reject 9L/IL-2 cells inoculated s.c., but developed 9L/IL-2 brain tumors by i.c. inoculation. The growth of i.c. 9L/IL-2 tumors was, however, significantly retarded compared with that of i.c. wild-type tumors. The growth of i.c. wild-type tumors was significantly suppressed when the rats concurrently received 9L/IL-2 cells s.c. Moreover, most of the rats that were inoculated i.c. with 9L/IL-2 cells did not develop brain tumors when concurrently injected s.c. with 9L/IL-2 cells. Immunohistochemical analysis on i.c. 9L/IL-2 tumors, when the rats were concurrently inoculated s.c. with 9L/IL-2 cells, revealed that migration of CD4+ or CD8+ T cells, monocytes/microglias, and macrophages was markedly augmented to a similar level as found in the s.c. 9L/IL-2 tumors. These results showed that systemic immune responses to brain tumor were induced in an immunologically privileged site by concurrent s.c. inoculation of the same tumors that produce IL-2. The present study may also raise the possibility of a therapeutic strategy for brain tumors by the combinatory expression of IL-2 gene using s.c. immunization followed by direct gene transfer into brain tumors.

Ceramide-induced apoptosis of human thyroid cancer cells resistant to apoptosis by irradiation

Ionizing radiation (IR) induces apoptosis through, in part, cell membrane breakdown signals. Ceramide and diacylglycerol (DAG) are released after IR exposure, which act as second messengers to induce proapoptotic and antiapoptotic signals, respectively. We have previously shown, however, that thyroid cells are relatively resistant to IR-induced apoptosis. To investigate the mechanism of thyroid cell resistance to IR-related apoptosis, we determined the effects of ceramide and its release following exposure of human thyroid cancer cell lines to IR. Exogenous C2-ceramide (10-100 microM) activated the apoptosis process in all cell lines used. Exogenous C2-ceramide also activated a stress kinase, c-Jun N-terminal kinase UNK). The apoptotic action of ceramide was attenuated by serum or simultaneous activation of protein kinases C and A by phorbol esters and forskolin. Furthermore, 2-5 Gy IR had a differential effect on ceramide and DAG release in human thyroid cells; a weak and transient release of ceramide but a strong and sustained release of DAG. Our results indicated that the radioresistance properties of thyroid cancer cells probably reflect the dominance of anti-apoptotic signals, evoked by growth factor(s) and DAG, which override the apoptotic effect of ceramide released by human thyroid cells on exposure to IR, in spite of activation of proapoptotic pathway downstream of ceramide.

Alteration of CDKN2/p16 in human astrocytic tumors is related with increased susceptibility to antimetabolite anticancer agents

A slowly proliferating cell fraction in tumors shows reduced sensitivity to cell cycle-dependent anticancer agents. To understand the molecular basis of drug resistance observed in brain tumors, we examined the relationship between alteration of p16, a cyclin dependent kinase inhibitor whose functions are frequently lost in many human gliomas, and chemosensitivity of tumor cells to various kinds of anticancer agents. Alterations of the p16 gene that include mutation(s) and homozygous deletion as well as p16 protein expression level, were examined in 56 specimens of astrocytic tumors. Their in vitro chemosensitivities to 30 kinds of anticancer agents were analyzed with flow cytometry which detects drug-induced cell death. We found that the alterations were correlated with increased sensitivity to antimetabolite anticancer agents but not with other kinds of agents, including alkylating agents, antibiotics, topoisomerase inhibitors and antimicrotubule agents. The present results suggest that p16 plays a role in determining chemosensitivity of brain tumors, depending on pharmacological mechanisms of anticancer agents. Proper understanding of the molecular machinery which regulates the chemosensitivity may contribute to the choice of anticancer agents for individual patients.

Transduction of the human deoxycytidine kinase gene in rodent tumor cells induces in vivo growth retardation in syngeneic hosts

Deoxycytidine kinase (dCK) mediates the phosphorylation of nucleoside analogues that can be used as anti-cancer agents. We examined whether susceptibility of mouse colon carcinoma (Colon 26) and rat gliosarcoma (9L) cells to 1-beta-D-arabiofuranosylcytonsine (AraC), a chemotherapeutic agent, can be increased after the tumor cells were transduced with the human dCK gene. Expression of the dCK gene in both cell lines conferred increased sensitivity in vitro to AraC. Although their proliferation rates in vitro remained the same as those of parental cells, tumor growth of the transduced cells in syngeneic host animals was unexpectedly retarded compared with that of respective parental cells. In contrast, the growth of the transduced cells was not different from that of parental cells, when they were inoculated in T cell-defective nude mice. A histological examination revealed infiltration of eosinophils into the dCK gene-transduced but not into parental Colon 26 tumor. These data suggest that a therapeutic gene, when expressed in xenogenic animals, can be a tumor antigen which is recognized by a host defense system.

Progressive loss of cortical acetylcholinesterase activity in association with cognitive decline in Alzheimer's disease: a positron emission tomography study

We measured brain acetylcholinesterase activity in 30 patients with Alzheimer's disease (AD) and 14 age-matched controls by positron emission tomography (PET) and using a carbon 11-labeled acetylcholine analogue. Seven AD patients had repeat PET scans. The k3 values were calculated as an index of acetylcholinesterase activity in a three-compartment analysis using the metabolite corrected arterial input function. Twenty-eight of the 30 AD patients (14 each in the early and late onset subgroups) were retained in the study so as to equalize the range and average severity of cognitive impairment within the early and late onset subgroups. The k3 values were significantly reduced in the neocortex, hippocampus, and amygdala in the early onset AD patients, although the k3 values were significantly reduced only in the temporoparietal cortex and amygdala in the late onset AD patients. In the longitudinal study, all 7 repeat AD patients showed further reduction of cortical k3 values in the second PET scans, with a mean interval of 2 years, suggesting a progressive loss of the ascending cholinergic system from the nucleus basalis of Meynert in AD. In 37 AD patients, there was a highly significant correlation between the cortical k3 values and Mini-Mental State Examination scores, supporting the cholinergic hypothesis in AD.

The p73 gene is not mutated in oligodendrogliomas which frequently have a deleted region at chromosome 1p36.3

An allelic loss of the chromosome 1p36 region is frequently found in oligodendrogliomas, which suggests the presence of putative tumor suppressor gene(s) in the region. Since the p73 gene, which encodes a protein with significant homology with p53, is mapped to the 1p36.33 region, we examined genetic alterations of the p73 gene in oligodendrogliomas. We screened 10 specimens for mutation throughout the p73 coding regions by polymerase chain reaction (PCR)-single strand conformation polymorphism analysis and by sequencing aberrantly migrated PCR products. We found several polymorphic nucleotide changes, but no somatic mutations that caused an amino acid change. The p73 gene is thus unlikely to be a tumor suppressor gene for oligodendrogliomas.

Inhibition of angiogenesis and tumorigenesis, and induction of dormancy by p53 in a p53-null thyroid carcinoma cell line in vivo

Our recent in vitro findings for suppression of thrombospondin-1 (TSP1; an antiangiogenic factor) expression by wild-type (wt) p53 in a p53-null thyroid carcinoma cell line, FRO, prompted us to investigate the in vivo effect of exogenous wt-p53 and TSP1 expression on tumor growth and angiogenesis of FRO xenografts in nude mice. Overexpression of TSP1, which did not affect the in vitro cell growth, significantly inhibited the in vivo tumor growth and neovascularization but not tumorigenesis; all the mice inoculated with FRO cells expressing TSP1 developed tumors, which were smaller and less vascularized than those derived from FRO cells. In contrast, restoration of wt-p53 expression, which reduced the in vitro cell growth rate, inhibited tumorigenesis and induced a state of "dormancy". Thus, approximately 40% of mice inoculated with FRO cells expressing wt-p53 (FRO-p53) were tumor free and the remaining mice developed hypovascular tumors which remained small (< or = 5 mm in size) for up to 60 days. Of interest, the phenotype of FRO-p53 tumors reverted to a well vascularized, progressively expanding tumor by exogenous expression of vascular endothelial growth factor (a proangiogenic factor). Our data demonstrated wt-p53 inhibition of tumorigenesis and induction of dormancy by suppression of neovascularization in FRO cells. The results suggest that p53 gene therapy for thyroid carcinoma harboring p53 mutation may be more efficacious than we had expected from previous in vitro data.

Treatment of rat experimental brain tumors by herpes simplex virus thymidine kinase gene-transduced allogeneic tumor cells and ganciclovir

Transfer of the herpes simplex virus thymidine kinase (HSVtk) gene, followed by administration of ganciclovir (GCV), generates the "bystander effect," in which HSVtk-negative wild-type cells are killed by GCV, as are HSVtk-expressing cells. Our previous study demonstrated that intracranial 9L gliomas could be efficiently treated due to this bystander effect by injecting the 9L glioma cells transduced with the HSVtk gene in the vicinity of the preimplanted wild-type 9L glioma and then administering GCV. For a possible clinical application of the bystander effect-mediated cell killing, we tested HSVtkgene-transduced allogeneic C6 glioma cells (C6tk) instead of syngeneic 9L glioma cells transduced with the HSVtk gene. Fisher rats were implanted intracranially with wild-type 9L glioma cells, subsequently injected with C6tk cells at the same brain coordinate, and thereafter treated with GCV or saline. When the rats were treated with GCV, a significant retardation of tumor growth was observed by serial magnetic resonance imaging, although this growth retardation was less prominent than that observed with 9L glioma cells transduced with the HSVtk gene; consequently, survival was prolonged (P < .01). Tumors that received C6tk cells contained almost no HSVtk-positive cells after treatment with GCV. Rejection of allogeneic tumor cells, although possibly incomplete in the brain, can also contribute to the safety of this therapeutic strategy.

Monitoring of human herpesvirus-6 and -7 genomes in saliva samples of healthy adults by competitive quantitative PCR

Human herpesviruses-6 and -7 (HHV-6 and HHV-7) are thought to be transmitted during early infancy through saliva. However, the kinetics of the virus shedding in saliva of healthy adults, from whom children are assumed to acquire the viruses, is mostly unknown. This study was conducted to determine how many copies of the genome are secreted in saliva of healthy adults and to clarify the relationship between viral DNA load and virus isolation of HHV-6 and HHV-7. Competitive PCR was performed using primer sets in the U42 gene of each viral genome. In saliva samples from 29 healthy adults, HHV-6 and HHV-7 DNA was detected in 41.4% and 89.7%, respectively. The average copy number of the HHV-7 genome in the positive samples was higher than that of the HHV-6 genome. Follow-up studies of six seropositive individuals for 3 months showed that the amount of HHV-7 DNA was constant in each individual and that "high producers" and "low producers" could be distinguished. By contrast, the amount of HHV-6 DNA varied drastically over time in each individual. Although HHV-6 was never isolated from the saliva of any of the six individuals during the follow-up period, HHV-7 was isolated from each individual several times. The amount of HHV-7 DNA tended to be higher at the times when the virus was isolated than at the times when the virus was not isolated. These data demonstrate a striking contrast between HHV-6 and HHV-7 in the kinetics of genome and virus shedding.

Suppressive effects of human herpesvirus-6 on thrombopoietin-inducible megakaryocytic colony formation in vitro

Two clinical observations, the association of human herpesvirus-6 (HHV-6) with delayed engraftment after stem cell transplantation and thrombocytopenia concomitant with exanthema subitum, prompted us to evaluate the suppressive effects of HHV-6 on thrombopoiesis in vitro. Different culture conditions for thrombopoietin (TPO)-inducible colonies in semi-solid matrices were examined. Using cord blood mononuclear cells as the source of haematopoietic progenitors, two types of colonies, megakaryocyte colony-forming units (CFU-Meg) and non-CFU-Meg colonies, were established. The former colonies were identified by the presence of cells with translucent cytoplasm and highly refractile cell membrane, most of which were positive for the CD41 antigen. Although the plating efficiency of both types was much higher under serum-containing conditions than under serum-free conditions, the proportion of CFU-Meg to non-CFU-Meg colonies was consistently higher under serum-free conditions. The plating efficiency of CFU-Meg colonies was doubled by adding stem cell factor to the serum-free matrix. The effects of two variants of HHV-6 (HHV-6A and 6B) and human herpesvirus-7 (HHV-7) on TPO-inducible colonies were then compared. HHV-6B inhibited both CFU-Meg and non-CFU-Meg colony formation under serum-free and serum-containing conditions. HHV-6A had similar inhibitory effects. In contrast, HHV-7 had no effect on TPO-inducible colony formation. Heat-inactivation and ultra-filtration of the virus sample completely abolished the suppressive effect. After infection of CD34(+) cells with HHV-6, the viral genome was consistently detected by in situ hybridization. These data suggest that the direct effect of HHV-6 on haematopoietic progenitors is one of the major causes of the suppression of thrombopoiesis.

Insulin-like growth factor-I (IGF-I)/IGF-I receptor axis and increased invasion activity of fibroblasts in keloid

Activation of signals for insulin-like growth factor-I receptor (IGF-IR) is thought to be closely linked to abnormal cell proliferation and differentiation in various diseases. The keloid in which fibroblasts invade beyond the margins of the original wound, is a dermal fibroproliferative tissue of unknown etiology. Clinically, keloids are most commonly observed in subjects at ages between 10 and 30 years. Interestingly, plasma levels of growth hormone and IGF-I are also high during the same period, suggesting that IGF-I might be involved in the patho-physiology of keloid fibroblasts. We therefore first examined the expression level of IGF-IR in normal and keloid tissues. Immunohistochemical analysis confirmed increased expression of IGF-IR in keloid fibroblasts, but not in normal fibroblasts. On the other hand, the staining intensity of IGF-IR in the epidermis of normal tissues was almost equal to that in keloids. Next, to study the functional properties of the IGF-I/IGF-IR axis in both normal and keloid fibroblasts, we investigated invasion activities. The invasive activity of IGF-IR overexpressing keloid fibroblasts was greatly increased in the presence of IGF-I, and inhibited by a neutralizing antibody to IGF-I. In contrast, its activity of IGF-IR weak-expressing normal fibroblasts was not changed. Our results indicate the involvement of the activated IGF-I/IGF-IR axis in the pathogenesis of the invasive activity of fibroblasts.

Significance of surgical resection for the treatment of multiple brain metastases

BACKGROUND

We investigated the role of surgery in the treatment of multiple brain metastases when performed with radiation therapy.

PATIENTS AND METHODS

One hundred and thirty-eight patients who underwent resection for brain metastases and received 30 Gy or more of adjuvant radiation therapy were entered into this study. Seventy-seven of the 138 patients (56%) had single brain metastases (Single Group), while the remaining 61 patients (44%) had multiple foci (Multiple Group). The 138 patients were divided into four subgroups; patients in Single Group treated with total or subtotal resection (Group A), those in Multiple Group who underwent total or subtotal resection and had remaining tumors smaller than 2 cm (Group B), those in Single Group treated with partial resection (Group C), and the other patients in Multiple Group (Group D).

RESULTS

The median survival was 8.7 and 9.2 months for the Single Group and the Multiple Group, respectively (not statistically different). The median survival was 9.6, 12.4, 3.7, and 4.5 months for Groups A, B, C, and D, respectively. Survival duration differed significantly between Groups A/B and Groups C/D (p < 0.05).

CONCLUSIONS

Surgical reduction of tumor volume which is approximately larger than 2 cm improves the efficacy of adjuvant radiation therapy and contributes to survival even in the patients with multiple brain metastases.

[Assumption of the area supplying Okayama Prefecture with Cryptomeria japonica and Cupressaceae airborne pollen, and of their scattering routes]

It is very important to predict and disseminate information about the total pollen counts of both Cryptomeria japonica and Cupressaceae for patients with pollinosis. In Okayama Prefecture, we have reported that the pollen counts of both Cryptomeria japonica and Cupressaceae are influenced by the meteorological conditions in the previous July. We predicted the area supplying Okayama Prefecture with Cryptomeria japonica and Cupressaceae pollen, and also the route of airborne pollen from the meteorological conditions and a topographical map of Okayama and four neighboring prefectures. It was found that Cryptomeria japonica and Cupressaceae pollen counts at the four observation sites correlated very well with the meteorological conditions at Tsuyama weather station in Okayama prefecture. Therefore, we considered that the areas supplying Okayama prefecture with Cryptomeria japonica and Cupressaceae pollen were the central northern areas including Tsuyama, 85.7% of whose plantation areas contained Cryptomeria japonica and Chamaecyparis obtusa, and that their pollen was carried along the routes of three major rivers, R. Takahashi, R. Asahi and R. Yoshii.

Homozygous deletion of the p16/MTS-1/CDKN2 gene in malignant gliomas is infrequent among Japanese patients

We have analyzed the status of the p16/MST-1/CDKN2 gene in 63 brain tumors from Japanese patients. With quantitative multiplex polymerase chain reaction (PCR) assay using the exon 2 primers of the p16 gene and control chromosome 9qSTS primers, we found homozygous deletion of the p16 gene in 7 cases; in 1 out of 10 cases of anaplastic astrocytomas (WHO grade III), 6 out of 35 cases of glioblastoma multiformes (grade IV) but in none of the tumors of grade I or II. We also found mobility-shifted PCR products in 8 cases using the single-strand conformation polymorphism technique. DNA sequencing of the aberrantly migrated products revealed that 5 cases of glioblastoma multiforme had mutations which caused amino acid substitutions. We found one case with silent mutations and two cases with nucleotide changes in the non-coding region. The frequency of the alteration of the p16 gene, either homozygous deletion or mutation accompanied with amino acid substitutions, increased in malignant brain tumors (grade III and IV) compared with that in low grade tumors (grade I and II) (p=0.0275), suggesting possible role(s) of the gene in the progression of brain tumors. In addition, the low frequency of homozygous deletions shown in this study is quite different from previous reports that demonstrated frequently deleted p16 gene in malignant gliomas from Caucasian patients. We have also shown the presence of heterogeneous cell populations within the glioblastoma masses based on the variety of the mutated p16 sequences. The present study, therefore, suggests a possible racial difference in the mechanism of the tumorigenesis and a heterogeneity of malignant gliomas developed during the tumor progression.

Glucose and methionine uptake and proliferative activity in meningiomas

Despite similar benign histological appearances, proliferative activity of meningiomas varies tumor to tumor, and even region to region in a tumor. To predict proliferative potential before surgery, we compared regional uptake of 2-[18F]fluoro-2-deoxyglucose ([18F]FDG) and L-[methyl-11C]methionine ([11C]MET) with histological indices of tumor proliferative activity in 17 specimens from six patients with meningioma obtained by PET guided stereotactic biopsies. Uptake of [11C]MET, an index of protein synthesis rate, significantly correlated not only with the count of nucleolar organizer regions (NORs), a histological index of protein synthesis, but also with Ki-67 index, a histological index of proliferative activity. On the other hand, [18F]FDG uptake showed no significant correlation with Ki-67 index or clinical malignancy. These results suggest that [11C]MET-PET is a useful tool for predicting tumor proliferative potential in meningiomas.

Transforming growth factor-beta stimulates articular chondrocyte cell growth through p44/42 MAP kinase (ERK) activation

Transforming growth factor-beta1 (TGF-beta1) stimulates articular chondrocyte cell proliferation and extracellular matrix formation. We reported previously that immediate and transient expression of c-fos mRNA through protein kinase C activation is required for the mitogenic effect of TGF-beta1 on cultured rat articular chondrocytes (CRAC). In gel kinase assays using myelin basic protein (MBP) showed that total cell lysates from cells treated with TGF-beta1 caused rapid phosphorylation of MBP, which suggests the involvement of mitogen-activated protein kinase (MAPK) activation. To identify specific MAPK pathways activated by TGF-beta1, we performed in vitro kinase assays using specific substrates. TGF-beta1 induced a rapid activation of extracellular signal regulated kinase (ERK) with a peak at 5 min, which decreased to basal levels within 240 min after TGF-beta1 stimulation. In contrast, the c-jun N-terminal kinase activity increased only about 2.5-fold after 240 min of stimulation and p38 MAPK activity did not change significantly. ERK activation by TGF-beta1 was also confirmed by in vivo phosphorylation assays of Elk1. However, a specific MEK1 inhibitor, PD98059, significantly decreased TGF-beta1 induced Elk1 phosphorylation in a dose-dependent manner. Furthermore, PD98059 reduced the TGF-beta1-induced cell growth by 40%. These results indicate that TGF-beta1 specifically activates MEK1 and subsequent ERK pathways in CRAC, and that the activation of this MAPK pathway plays a role in the mitogenic response to TGF-beta1.

Enhanced efficacy of transcriptionally targeted suicide gene/prodrug therapy for thyroid carcinoma with the Cre-loxP system

Our recent study demonstrates the feasibility of the thyroglobulin (TG) promoter in transcriptionally targeted gene therapy for thyroid carcinomas expressing TG, albeit less effectively than the constitutive viral promoter. The present study was, therefore, designed to enhance the activity of the TG promoter with the Cre-loxP system. Our data demonstrate that the in vitro cytotoxic effect of herpes simplex virus thymidine kinase/ganciclovir obtained with the TG promoter and the Cre-loxP system is approximately 5-10-fold higher than that with the TG promoter alone. Enhanced tumor growth inhibition was also observed in in vivo tumor models. These data indicate the usefulness of the Cre-loxP system to enhance the activity of a tissue (or tumor)-specific promoter in transcriptionally targeted cancer gene therapy.

Positron emission tomographic measurement of acetylcholinesterase activity reveals differential loss of ascending cholinergic systems in Parkinson's disease and progressive supranuclear palsy

We measured brain acetylcholinesterase activity in 16 patients with Parkinson's disease (PD), 12 patients with progressive supranuclear palsy (PSP), and 13 age-matched controls, using N-methyl-4-[11C]piperidyl acetate and positron emission tomography. Kinetic analysis was performed to calculate k3, an index of acetylcholinesterase activity. In PD patients, there was a significant reduction (-17%) of cerebral cortical k3 compared with normal controls, whereas there was only a nonsignificant reduction (-10%) of cortical k3 in PSP patients. However, there was a prominent reduction (-38%) of thalamic k3 in PSP patients compared with normal controls, whereas there was only a nonsignificant reduction (-13%) of thalamic k3 in PD patients. The results suggest that there is a loss of cholinergic innervation to the cerebral cortex in association with cholinergic innervation to the thalamus in PD, whereas there is a preferential loss of cholinergic innervation to the thalamus in PSP. When the thalamic to cerebral cortical k3 ratio was taken for each subject, PD and PSP were separated, suggesting that positron emission tomography measurement of acetylcholinesterase activity may be useful for differentiating the two similar disorders.

Accumulation of milky fluid: a late complication of cataract surgery

We describe 3 patients who presented with an accumulation of homogeneous milky fluid in the capsular bag several years after continuous curvilinear capsulorhexis, phacoemulsification, and posterior chamber intraocular lens (IOL) implantation. In each case, the entire edge of the anterior capsule opening was tightly attached to the peripheral IOL optic. The milky fluid was present in the closed chamber between the IOL optic and the posterior capsule. The fluid was sampled in 2 patients, and its concentration of sodium hyaluronate was determined by high-performance liquid chromatography. The concentration of sodium hyaluronate resembled that in normal aqueous humor. In 1 case, the protein concentration was measured and found to be elevated. Electrophoresis showed that human serum albumin was the main protein constituent. While the outcome was favorable in all 3 patients, this delayed complication of cataract surgery merits further study to clarify its etiology and pathogenesis.

Coordination of limb movements: three types of intersegmental interneurons in the swimmeret system and their responses to changes in excitation

Coordination of limb movements: three types of intersegmental interneurons in the swimmeret system and their responses to changes in excitation. During forward locomotion, the movements of swimmerets on different segments of the crayfish abdomen are coordinated so that more posterior swimmerets lead their anterior neighbors by approximately 25%. This coordination is accomplished by mechanisms within the abdominal nerve cord. Here we describe three different types of intersegmental swimmeret interneurons that are necessary and sufficient to accomplish this coordination. These interneurons could be identified both by their structures within their home ganglion and by their physiological properties. These interneurons occur as bilateral pairs in each ganglion that innervates swimmerets, and their axons traverse the minuscule tract (MnT) of their home ganglion before leaving to project to neighboring ganglia. Two types, ASCE and ASCL, projected an axon anteriorly; the third type, DSC, projected posteriorly. Each type fires a burst of impulses starting at a different phase of the swimmeret cycle in its home ganglion. In active preparations, excitation of individual ASCE or DSC interneurons at different phases in the cycle affected the timing of the next cycle in the interneuron's target ganglion. The axons of these interneurons that projected between two ganglia ran close together, and their firing often could be recorded by the same electrode. Experiments in which either this tract or the rest of the intersegmental connectives was cut bilaterally showed that these interneurons were both necessary and sufficient for coordination of neighboring swimmerets. When the level of excitation of the swimmeret system was increased by bath application of carbachol, the period of the system's cycle shortened, but the characteristic phase difference within and between ganglia was preserved. Each of these interneurons responded to this increase in excitation by increasing the frequency of impulses within each burst, but the phases and relative durations of their bursts did not change, and their activity remained coordinated with the cycle in their home ganglion. The decrease in duration of each burst was matched to the increase in impulse frequency within the burst so that the mean numbers of impulses per burst did not change significantly despite a threefold change in period. These three types of interneurons appear to form a concatenated intersegmental coordinating circuit that imposes a particular intersegmental phase on the local pattern generating modules innervating each swimmeret. This circuit is asymmetric, and forces posterior segments to lead each cycle of output.

Thyrotropin regulates c-Jun N-terminal kinase (JNK) activity through two distinct signal pathways in human thyroid cells

c-Jun N-terminal kinases (JNK) participate in cellular responses to mitogenic stimuli and environmental stresses. We investigated whether and how TSH, which promotes the proliferation and differentiation of thyroid cells, regulates JNK activity in primary cultured human thyroid cells. TSH stimulated JNK activity in cytosolic fractions of thyroid cells measured by in vitro kinase assay. A low concentration of TSH (10(-11) M) stimulated JNK activity but at a higher dose (10(-8)-10(-7) M), TSH suppressed JNK activity without any change of JNK protein level. Activation of JNK by TSH was also observed in CHO cells stably transfected with TSH receptor complementary DNA (cDNA), suggesting a ligand-receptor specific interaction. TSH stimulated JNK activity through a pertussis toxin-sensitive pathway. We next elucidated the signal transduction pathways in TSH-induced JNK activation by examining the involvement of four distinct intracellular signal molecules; protein kinase C (PKC), cAMP, Ca2+, and PI3-kinase. The stimulation of JNK by TSH was blocked by two PKC inhibitors and suppressed by 8-bromo-cAMP or forskolin. These findings demonstrate that TSH regulates JNK activity biphasically in human thyroid cells through an interaction between Gi-PKC and cAMP-PKA pathways.

Effect of 22-oxa-1,25-dihydroxyvitamin D3 on human thyroid cancer cell growth

To examine whether synthetic vitamin D3 analog, 22-oxa-1,25(OH)2D3 (OCT) has an inhibitory effect on the growth of thyroid carcinoma, we tested the in vitro and in vivo effects of OCT on the growth of a well-differentiated thyroid cancer cell line, NPA. OCT bound to its receptor at the same rate as 1,25(OH)2D3, and inhibited the proliferation of NPA cells in vitro in a dose-dependent manner, similar to that observed with 1,25 (OH)2D3. Northern blot analysis showed that steady-state and fetal bovine serum-stimulated levels of c-myc mRNA were suppressed after 0.5-4 hour treatment with OCT. Transfection studies with the deletion mutants of the 5'-up-stream flanking region of c-myc/chloramphenicol acetyltransferase chimera genes indicated the presence of an OCT responsive element between -410 and -106. Next, we examined OCT effects in implanted NPA tumor cells in nude mice. OCT showed no remarkable hypercalcemic effect compared to 1, 25 (OH2)D3, but OCT and 1, 25 (OH2)D3, had no significant inhibitory effect in vivo after either intra-tumor or intra-peritoneum injection. Our results demonstrate that OCT inhibits the proliferation of well-differentiated thyroid cancer in an in vitro system associated with the suppression of c-myc mRNA, but this inhibitory effect was not reproducible in in vivo model.

Overexpression of insulin-like growth factor-1 (IGF-I) receptor and the invasiveness of cultured keloid fibroblasts

Keloid is a dermal fibroproliferative tissue of unknown etiology. Protein tyrosine kinases (PTKs) play an important role in the regulation of cell growth and differentiation. Activation of PTK cascades in keloid fibroblasts is thought to be closely linked to abnormal cell proliferation and migration. We determined the expression profile of PTK genes in normal skin and keloid fibroblasts using the homology cloning method with a degenerated primer. Eight PTK genes were expressed among a total of 46 receptor-type clones. The most abundant type of PTK receptors was the platelet-derived growth factor receptor in both fibroblasts. However, insulin-like growth factor-I receptor (IGF-IR) was overexpressed only in keloid-derived fibroblasts (9 of 24). Immunohistochemical analysis confirmed the high expression of IGF-IR in keloid fibroblasts, but not in normal fibroblasts. To examine the functional properties of the IGF-I/IGF-IR pathway, we investigated cell proliferation and invasion activities of both types of fibroblasts. The mitogenic effect of IGF-I on both fibroblasts was very weak compared with serum stimulation. In contrast, the invasive activity of keloid fibroblasts was markedly increased in the presence of IGF-I, and inhibited by a neutralizing antibody against IGF-IR. Our results indicate the involvement of activated IGF-I/IGF-IR in the pathogenesis of keloid by enhancing the invasive activity of fibroblasts.

Human cerebral acetylcholinesterase activity measured with positron emission tomography: procedure, normal values and effect of age

The regional cerebral metabolic rate of [11C]N-methyl-4-piperidyl acetate, which is nearly proportional to regional cerebral acetylcholinesterase (AChE) activity, was measured by dynamic positron emission tomography in 20 healthy subjects with a wide age range (24-89 years). Quantitative measurement was achieved using a kinetic model which consisted of arterial plasma and cerebral tissue compartments. The plasma input function was obtained using thin-layer chromatography and an imaging phosphor plate system at frequent sampling intervals to catch the rapid metabolism of the tracer in the blood. The distribution of the rate constant k3, an index of AChE activity, agreed well with reported post-mortem AChE distribution in the cerebral cortex (0.067-0.097 min-1) and thalamus (0.268 min-1), where AChE activity was low to moderate. The k3 values in the striatum and cerebellum, where AChE activity was very high, did not respond linearly to AChE activity because of increased flow dependency. No significant effect of age was found on AChE activity of the cerebral cortex, suggesting that the ascending central cholinergic system is preserved in normal aging. This study has shown that quantitative measurement of enzyme activity in the living brain is possible through appropriate modelling of tracer kinetics and accurate measurement of the input function. The method should be applicable to patients with Alzheimer's disease and those with other kinds of dementia whose central cholinergic system has been reported to be disturbed.

Role of asparagine-linked oligosaccharides in protein folding, membrane targeting, and thyrotropin and autoantibody binding of the human thyrotropin receptor

The amino-terminal ectodomain of thyrotropin (TSH) receptor (TSHR) is heavily glycosylated with asparagine-linked (N-linked) oligosaccharides. The present studies were designed to evaluate how acquisition and processing of N-linked oligosaccharides play a role in the functional maturation of human TSHR. A glycosylation inhibitor tunicamycin, which inhibits the first step of N-linked glycosylation (acquisition of N-linked oligosaccharides), and a series of mutant Chinese hamster ovary (CHO)-Lec cells defective in the different steps of glycosylation processing were used. Inhibition of acquisition of N-linked oligosaccharides by tunicamycin treatment in CHO cells stably expressing TSHR produced nonglycosylated TSHR, which was totally nonfunctional. In contrast, all of the TSHRs synthesized in mutant CHO-Lec1, 2, and 8 cells (mannose-rich, sialic acid-deficient, and galactose-deficient oligosaccharides, respectively) bound TSH and produced cAMP in response to TSH with an affinity and an EC50 similar to those in TSHR expressed in parental CHO cells (CHO-TSHR; sialylated oligosaccharides). However, Lec1-TSHR and Lec2-TSHR were not efficiently expressed on the cell surface, whereas the expression levels of Lec8-TSHR and CHO-TSHR were essentially identical. All of the TSHRs expressed in CHO-Lec cells cleaved into two subunits. Finally, anti-TSHR autoantibodies from Graves' patients interacted with all of the TSHRs harboring different oligosaccharides to a similar extent. These data demonstrate that acquisition and processing of N-linked oligosaccharides of TSHR appear to be essential for correct folding in the endoplasmic reticulum and for cell surface targeting in the Golgi apparatus. We also show that complex type carbohydrates are not crucially involved in the interaction of TSHR with TSH and anti-TSHR autoantibodies.

Intersegmental coordination of swimmeret movements: mathematical models and neural circuits

Swimmerets move periodically through a cycle of power-strokes and return-strokes. Swimmerets on neighboring segments differ in phase by approximately 25%, and maintain this difference even when the period of the cycle changes from < 1 to > 4 Hz. We constructed a minimal cellular model of the segmental pattern-generating circuit which incorporated its essential components, and whose dynamics were like those of the local circuit. Three different intersegmental coordinating units were known to link neighboring ganglia, but their targets are unknown. We constructed different intersegmental circuits which these units might form between neighboring cellular models, and compared their dynamics with the real system. One intersegmental circuit could maintain an approximately 25% phase difference through a range of periods. In physiological experiments, we identified three types of intersegmental interneurons that originate in each ganglion and project to its neighbors. These neurons fire bursts at certain parts of the swimmeret cycle in their home ganglion. These three neurons are necessary and sufficient to maintain normal coordination between neighboring segments. Their properties conform to the predictions of the cellular model.

Therapeutic usefulness of wild-type p53 gene introduction in a p53-null anaplastic thyroid carcinoma cell line

Anaplastic thyroid carcinomas very often harbor the mutations in the tumor suppressor gene p53. We have previously shown that wild-type (wt) p53 gene introduction led to cell growth arrest, but not apoptosis, in p53-null anaplastic thyroid carcinoma cells. The present studies were designed to evaluate other therapeutic effects of wt-p53 gene introduction on p53-null thyroid carcinoma cells, as chemo- and radiosensitization and inhibition of angiogenesis have also been described recently as additional therapeutic advantages of wt-p53 gene introduction in tumor cells with p53 mutations. A p53-null anaplastic thyroid carcinoma cell line, FRO, and a FRO subline stably expressing a temperature-sensitive (ts) mutant of p53 (p53Val138), tsFRO, were used. ts-p53 functions as mutant and wt at nonpermissive (37 C) and permissive (32 C) temperatures, respectively. tsFRO showed a prolonged cell doubling time compared to parental FRO when cultured at 32 C, but the cell growth rate was similar between FRO and tsFRO at 37 C. The cytotoxic and clonogenic assays demonstrated that although the sensitivity to three different anticancer agents (cisplatin, 5-fluorocytosine, and doxorubicin) was unaltered, radiosensitivity was enhanced in tsFRO compared to FRO at 32 C. Unexpectedly, in studies on angiogenesis, expression levels of vascular endothelial growth factor (an angiogenic factor) messenger ribonucleic acid were similar between FRO and tsFRO, and thrombospondin-1 (an antiangiogenic factor) messenger ribonucleic acid and protein levels were about 2.5-fold lower in tsFRO than FRO at 32 C, although any difference could not be detected in their ability to inhibit in vitro angiogenesis with the culture medium conditioned by tsFRO and FRO at 32 C. These results suggest that p53-defective thyroid carcinomas may benefit from the combination of p53 gene therapy and radiotherapy. However, further study will be necessary to clarify the pathological significance of thrombospondin-1 in angiogenesis and thyroid tumor growth.

Retrovirus-mediated suicide gene/prodrug therapy targeting thyroid carcinoma using a thyroid-specific promoter

To develop gene therapy targeting thyroid carcinoma, the recombinant retrovirus (LNTGTK) carrying herpes simplex virus thymidine kinase (HSV-TK) gene under the control of thyroglobulin (TG) promoter was constructed and its efficacy was investigated in 3 thyroid cell lines; a differentiated normal rat thyroid cell line (FRTL5), malignant rat thyroid carcinoma cells derived from FRTL5 (FRTC) and a human anaplastic thyroid carcinoma cell line (FRO). TG mRNA was detected by Northern blot analysis in FRTL5 cells and by RT-PCR in FRTC cells when cultured with 2 U/L TSH and its expression levels were decreased by TSH withdrawal. However, either methods revealed no TG expression in FRO cells. In vitro cytotoxic assays demonstrated TG expression status-dependent cell killing by transduction of LNTGTK followed by ganciclovir (GCV) treatment. Thus, LNTGTK transduction increased the GCV sensitivity approximately 13,000- and approximately 160-folds in the presence of TSH and approximately 4- and approximately 27-folds in the absence of TSH in FRTL5 and FRTC cells, respectively. In contrast, there was no difference in the GCV cytotoxicity between parental and transduced FRO cells. Significant growth inhibition, but not complete eradication, of transduced FRTC cells was observed in in vivo subcutaneous tumor models of nude mice. These results demonstrate that retrovirus-mediated transduction of HSV-TK gene under the control of the TG promoter confers the GCV sensitivity selectively to TG-expressing thyroid cells. This system may therefore be feasible for gene therapy targeting TG-expressing thyroid carcinomas.