Development of a dot blot neutralizing assay for HHV-6 and HHV-7 using specific monoclonal antibodies

To elucidate further immune responses to human herpesviruses 6 and 7 (HHV-6 and -7), a neutralizing antibody assay was established for these viruses using a dot blot method. Three monoclonal antibodies against HHV-6 and 12 monoclonal antibodies against HHV-7 were developed and characterized by radio-immunoprecipitation. One monoclonal antibody which recognizes the 135 kDa late polypeptide of HHV-6 and several which recognize the 125 kDa late polypeptide of HHV-7 were selected to monitor virus growth by a dot blot antigen-detection method. The dot blot method was then used for the assay of HHV-6 and -7 neutralizing antibodies in human serum samples. The neutralization endpoints determined by the dot blot were comparable to those determined by immunofluorescence (IF). The neutralizing antibody titers appeared to correlate with the antibody titers determined by the indirect IF antibody test. The dot blot neutralization assay is easy to perform, is highly reproducible and objective when compared with the conventional methods based on cytopathology or IF for determining neutralization endpoints.

ret rearrangements in Japanese pediatric and adult papillary thyroid cancers

Oncogenic rearrangements of the ret proto-oncogene (ret/PTC) are found uniquely in papillary thyroid carcinomas. The prevalence of ret/PTC in these tumors varies widely, from 0% to 87%, among patient series from different geographical regions. The differences in the prevalence of ret rearrangement have been ascribed to age, genetic, and/or environmental factors. The very high prevalence of ret/PTC in tumors arising in children after the Chernobyl nuclear accident has generated speculation that this oncogene may be an indicator of overt or inadvertent radiation exposure. In Japan, the prevalence of ret activation is reportedly quite low (0% to 9%). Here we examined the frequency of ret rearrangements in papillary carcinomas from Japanese adults and children by means of reverse transcription polymerase chain reaction (RT-PCR) followed by Southern hybridization. Ret rearrangements were detected in 4 of 11 (36%) tumors from the adult population, and in 3 of 10 (30%) pediatric tumors. One child with a solid variant papillary carcinoma had a ret-PTC3 rearrangement, further supporting the association between the solid variant histotype and this particular rearrangement of ret. The present data do not support a major geographic difference in the prevalence of ret/PTC rearrangements in papillary carcinomas between Japan, the United States, and Italy.

Treatment of thyroid carcinoma cells with four different suicide gene/prodrug combinations in vitro

To develop a suitable suicide gene/prodrug therapy for the treatment of thyroid carcinomas, the relative therapeutic efficacy of four different suicide gene/prodrug combinations was compared in thyroid carcinomas in vitro. Herpes simplex virus thymidine kinase and ganciclovir (HSV-TK/GCV), Escherichia coli cytosine deaminase and 5-fluorocytosine (CD/5FC), E coli nitroreductase and CB1954 (NTR/CB1954), and human deoxycytidine kinase and cytosine arabinoside (dCK/AraC) were employed. The suicide genes were transduced into two thyroid carcinoma cell lines with retroviral vectors in which all the suicide genes were under the control of the same promoter. When the relative efficacy of four suicide gene/prodrugs was compared with therapeutic index and degree of bystander effect, we found a clear dissociation between these two parameters. Thus, HSV-TKIGCV demonstrated the widest therapeutic index, while CD/5FC and NTR/CB1954 showed the stronger bystander effect than HSV-TK/GCV. dCK/AraC had little efficacy. Advantages and limitations of each suicide gene/prodrug combinations are discussed.

Improvement of spectrometer energy resolution for high-resolution photoelectron spectroscopy

For high-energy-resolution photoelectron spectroscopy using synchrotron radiation, the energy resolution of a commercial compact photoelectron spectrometer (hemispherical concentric spectrometer) was improved by reducing the size of the entrance and detector slits and optimizing the operation conditions of the lens voltage. Under the optimized conditions, ray-tracing simulations show that severe spectral intensity decreases can be avoided. An energy resolution of 6.2 meV and a resolving power of 8100 at a kinetic energy of 50 eV were experimentally obtained.

A compact vacuum-ultraviolet beamline for synchrotron radiation photoelectron spectroscopy combined with an ion-scattering spectrometer, SORIS

Apparatus for high-resolution synchrotron radiation photoelectron spectroscopy combined with high-resolution medium-energy ion scattering, named 'SORIS', has been developed for simultaneous investigations of electronic states and atomic structures on surfaces. For this purpose, a compact vacuum-ultraviolet beamline of photon energy from 5 to 700 eV has been designed for the small storage ring 'Aurora' installed at Ritsumeikan University. Owing to the small electron-beam size in the storage ring, an energy resolution E/dE of >5000 can be obtained.

Glucose and methionine uptake by rat brain tumor treated with prodrug-activated gene therapy

The effect of acyclovir (ACV) on the metabolism of rat 9L-gliosarcoma cells expressing the herpes simplex virus-thymidine kinase gene was studied using 2-deoxy-2-[18F]fluoro-D-glucose (FDG) and L-[methyl-11C]methionine. Though the average weight of the tumors treated with ACV was significantly lower than that of the saline-injected control group, FDG and methionine uptake per weight of tumor tissue was not different between the two groups. This result exhibits a striking contrast to the metabolic pattern observed after radiation therapy, suggesting the different pathways regarding tumor cell death between the therapies.

Childhood thyroid cancer: comparison of Japan and Belarus

The high incidence of childhood thyroid cancer in Belarus is suspected to be due to radiation exposure after the Chernobyl reactor accident. To clarify the clinical and histological characteristics of childhood thyroid cancer in Belarus, we therefore compared these patients to a radiation non-exposed control series in Japan. In Belarus, 26 thyroid cancers in subjects aged 15 or younger were diagnosed among 25,000 screened between 1991 and 1995 by Chernobyl-Sasakawa Health and Medical Cooperation Project. The clinical and morphologic features of these 26 cases were compared to 37 childhood thyroid cancers in Japan diagnosed between 1962 and 1995. The age distribution at operation in Belarus showed a peak at 10 years old, with a subsequent fall in numbers. In contrast, the age distribution at operation in Japan showed a smooth increase between the ages of 8 and 14. The mean tumor diameter was smaller in Belarus than that in Japan (1.4 +/- 0.7 vs. 4.1 +/- 1.7 cm, P < 0.001). The sex ratio, regional lymph node metastasis, extension to surrounding tissues or lung metastasis did not differ significantly. Histologically, all cases in Belarus were papillary and in Japan 33 cases were papillary and 4 cases were follicular carcinomas. Among papillary carcinomas, the frequency of a solid growth pattern, a criteria for classifying a tumor as poorly differentiated, was higher in Belarus than that in Japan (61.5 vs. 18.2%, P < 0.001). The difference between the features of childhood thyroid cancer in Japan and Belarus may be due to the difference in the process of carcinogenesis, but more direct evidence and further analysis by molecular epidemiology are needed in Belarussian cases.

Ionizing radiation activates c-Jun NH2-terminal kinase (JNK/SAPK) via a PKC-dependent pathway in human thyroid cells

Thyroid gland is known to be higher sensitive to carcinogenic effects of external ionizing radiation (IR) than other tissues. To clarify the cell-specific response following irradiation, activations of c-Jun NH2-terminal kinases (JNKs), which is one of mitogen-activated protein kinases (MAPKs) family members, and extracellular signal-regulated kinase (ERK) were examined in primary cultured human thyroid cells in comparison with human diploid fibroblast cells, WI-38. Although UV exposure strikingly induced JNK activity in both cells, the dose-response increase following IR exposure was observed in thyroid cells with the maximal JNK activity (3.5 fold induction) obtained at 10 Gy exposure, but no increase in WI-38 cells. The JNK activity was reached a maximum of 2.2 fold induction at 30 min after 5 Gy exposure and then sustained for at least 12 hr. On the other hand, ERK activity was not stimulated in thyroid cells following irradiation. The effects of 12-O-tetradecanoylphorbol beta-acetate (TPA) mimicked those of radiation on JNK cascade and 1-(5-isoquinolinesulphonyl)-2,5-dimethylpiperazine 2HCl (H7) and pretreatment with TPA blocked JNK activation following irradiation. Our results demonstrate that IR stimulates JNK activity in cultured human thyroid cells but not in fibroblasts indicating distinct activation and regulation mechanisms of JNK cascade. The JNK activation following IR exposure is mediated at least partially through a PKC-dependent pathway.

Expression profile of receptor-type protein tyrosine kinase genes in the human thyroid

Protein tyrosine kinases (PTKs) play a role in regulating the growth and differentiated functions of thyroid cells and are probably involved in tumorigenesis of papillary-type thyroid carcinoma. To better understand the roles of PTKs in the physiology and pathophysiology of the thyroid, we analyzed the expression profile of receptor-type PTKs in normal human thyroid tissues. Highly conserved regions in the catalytic domains of receptor-type PTKs were amplified by RT-PCR using degenerate oligonucleotide primers. Nucleotide sequencing of about 100 clones identified 21 PTKs, including 16 receptor type and 5 nonreceptor type; no novel PTK was identified. Insulin-like growth factor I receptor, platelet-derived growth factor receptor (PDGFR), TrkE, Axl, epidermal growth factor receptor, etc., appear to be the most abundant receptor-type PTKs in the thyroid; many of which (PDGFR, TrkE, Axl, etc.) have never previously been demonstrated to be expressed in the thyroid. The expression of messenger RNAs (mRNAs) for PDGFR, axl, and trkE in normal thyroid cells was confirmed by Northern blot analysis, and interestingly, the expression levels of PDGFR and trkE mRNAs were decreased in all three thyroid carcinoma cell lines examined (FRO, WRO, and NPA), whereas axl mRNA and protein were overexpressed in 2 of 3 thyroid carcinoma cell lines (FRO and WRO) compared with that in normal tissue. The axl gene was, however, neither amplified nor rearranged. The biological activity of the ligand for Axl, the product of growth arrest-specific gene 6 (Gas6), was then evaluated, demonstrating modest mitogenic activity in thyroid carcinoma cells overexpressing Axl. Furthermore, gas6 mRNA was expressed in FRO cells. Thus, we here identify a variety of PTKs expressed in the thyroid gland, many of which may participate in the regulation of thyroid cell function. Variable expression levels of some PTKs in normal and cancerous cells suggest that there may be an imbalance and disarray of phosphorylation events in thyroid carcinoma cells. Furthermore, Gas6 is identified as a novel growth factor for thyroid carcinoma cells overexpressing Axl receptor tyrosine kinase.

Mutation of the p53 gene in human astrocytic tumours correlates with increased resistance to DNA-damaging agents but not to anti-microtubule anti-cancer agents

Astrocytic tumours often become resistant to a variety of chemotherapeutic agents in advanced stages and frequently possess mutations in the p53 tumour-suppressor gene. Previous studies using established cell lines to investigate the relation between mutated p53 genes and altered resistance to anti-cancer agents brought inconsistent results. In this report, we examined the status of the p53 gene in 56 astrocytic tumour specimens by single-strand conformation polymorphism and their in vitro chemosensitivity to 30 different kinds of anti-cancer agents. The chemosensitivity was determined by drug-induced cell death using flow cytometry. We found that the mutated p53 gene correlated with increased resistance to DNA-damaging agents but the sensitivity to anti-microtubule agents was independent of the mutation, suggesting a clinical significance of the status of p53 gene in astrocytic tumours and a rational application of anti-microtubule agents to the patients with p53-mutated astrocytic tumours.

Palmitoylation of human thyrotropin receptor: slower intracellular trafficking of the palmitoylation-defective mutant

We here show that the epitope-tagged human TSH receptor (TSHRmyc) is covalently modified with palmitic acid by thioesterification. Side-directed mutagenesis identified Cys699 in the C-terminal cytoplasmic tail of the receptor as the putative palmitoylation site. Mutation of Cys699 to Ala results in the nonpalmitoylated receptor (TSHRmycC699A) in which high affinity TSH binding, Gs coupling, homologous desensitization and TSH-induced internalization are unaffected. In contrast, abolition of palmitoylation appears to decrease the rate of the intracellular trafficking of the receptor. However, since most of TSHRmycC699A seems to be fully processed finally and the receptor number of TSHRmycC699A on the cell surface is comparable to that of TSHRmyc, our results suggest that abolition of palmitoylation delays the cell surface expression of TSHR, but does not trap the receptor intracellularly, although another possibility for proteolytic degradation of either the 95 kDa or the 100 kDa mutant receptor can not be excluded. Thus, post-translational modification of TSHR by palmitoylation may provide a novel mechanism of enhancing the rate of intracellular trafficking of the receptor.

Bystander effect-mediated therapy of experimental brain tumor by genetically engineered tumor cells

Transfer of the herpes simplex virus-thymidine kinase (HSV-tk) gene, followed by administration of ganciclovir (GCV), generates the "bystander effect," in which HSV-tk-negative wild-type cells, as well as HSV-tk-expressing cells, are killed by GCV. To eradicate an intracranial tumor by this bystander effect, we injected the tumor cells transduced with the HSV-tk gene (TK cells) in the vicinity of the preimplanted wild-type tumor and then administered GCV. Wild-type 9L-gliosarcoma cells (1 x 10[5]) were implanted into the brain of syngeneic Fisher rats. On the next day, rats were injected with TK cells (1 x 10(5) or 3 x 10[5]) or medium alone at the same brain coordinate and then treated with GCV or saline. Administration of GCV significantly prolonged the survival of the rats injected with TK cells compared with that injected with medium alone (p < 0.01). Reduction in tumor size and retardation of tumor growth were observed by serial magnetic resonance imaging in the rats that received the combination of TK cells and GCV. The results show that the bystander effect is also achieved in vivo even when TK cells and wild-type cells are not simultaneously implanted. This treatment modality circumvents potential risks accompanied with in vivo gene transfer. Because there remained substantially no HSV-tk-positive cells in the recurrent tumors, this modality offers a "safe" therapeutic strategy against human malignant gliomas.

Distribution of GABAergic premotor nonspiking local interneurones in the terminal abdominal ganglion of the crayfish

The inhibitory neurotransmitter of premotor nonspiking local interneurones in the crayfish terminal abdominal ganglion was investigated physiologically and immunocytochemically. Depolarization of a nonspiking interneurone evoked a hyperpolarization in a uropod motor neurone. The amplitude of hyperpolarization in the motor neurone was gradually decreased under low-calcium/high-magnesium saline. Local pressure injection of gamma-aminobutyric acid (GABA) into the neuropil caused a similar hyperpolarization of the motor neurone. These physiological studies suggested a GABAergic inhibitory interaction between nonspiking interneurones and the motor neurones. Premotor nonspiking interneurones are classified into two subgroups ofposterolateral (PL) and anterolateral (AL) interneurones, and AL interneurones are further divided into three subtypes. A combination of intracellular staining from nonspiking local interneurones with Lucifer yellow and immunocytochemical staining with an antiserum directed against GABA revealed that all the PL interneurones sampled in this study showed GABA-like immunoreactivity. A population of cell bodies (n = 6-11) with a small diameter (15-30 microm) packed together forming a cluster showed GABA-like immunoreactivity, and the cell bodies of most PL interneurones were found in this cluster. To compare the number and the pattern of main branches of PL interneurones, cells were classified into three identifiable sets of interneurones, called PL-1, PL-2, and PL-3. By contrast, about one-half of AL interneurones, especially the third subtype of AL interneurones, which have cell bodies located ventrolaterally in the ganglion, did not show GABA-like immunoreactivity. Furthermore, the position of cell bodies of GABA-immunoreactive AL interneurones was scattered compared to that of PL interneurones.

Retrovirus-mediated herpes simplex virus thymidine kinase gene transduction renders human thyroid carcinoma cell lines sensitive to ganciclovir and radiation in vitro and in vivo

In an attempt to develop gene therapy for thyroid carcinomas, the present studies were undertaken to evaluate in vitro and in vivo therapeutic efficacy and toxicity of herpes simplex virus thymidine kinase (HSV-tk) gene and ganciclovir (GCV) treatment, a widely used prodrug/suicide gene therapy, in human thyroid carcinoma cell lines, FRO and WRO cells, using a means of retrovirus-mediated gene transduction. In vitro experiments demonstrated dose- and time-dependent cell killing by transduction of the HSV-tk gene followed by GCV treatment. The IC50 (the concentration required to elicit 50% growth inhibition) shifted from 250 to 0.5 mg/liter in FRO cells, and from 3,000 to 0.09 mg/liter in WRO cells with therapeutic indexes of 500 and 33,000, respectively. Treatment with 30 mg/liter GCV for 4 days led to complete cell death in HSV-tk tumor cells. Nontransduced cells mixed with transduced cells were also effectively killed by GCV (bystander effect). Low concentrations of GCV, which alone showed little cytotoxicity, enhanced radiation-induced cytotoxicity (radiosensitization). In vivo sc FRO-tk tumor models in nude mice also showed dose- and time-dependent tumor regression. The IC50 was less than 2 mg/kg, and treatment with 100 mg/kg GCV for 2 weeks completely eradicated all tumors. The bystander effect and radiosensitization were also obtained in vivo. These results suggest that the HSV-tk/GCV approach to human thyroid carcinoma cells appears to be very efficacious, with a wide therapeutic range, and exerts a bystander effect and radiosensitization both in vitro and in vivo. Thus, HSV-tk/GCV system, alone or in combination with radiotherapy, may be a promising suicide gene therapy for thyroid carcinomas.

[Quantitative measurement of cerebral blood flow by the microsphere model with super-early 123I-IMP brain SPECT]

Cerebral blood flow (CBF) was quantitatively measured in 6 healthy young volunteers based on "super-early" acquisition of N-isopropyl-p-[123I]iodoamphetamine (IMP) brain SPECT obtained 4-6 min after IMP injection with a three-head rotating gamma camera and the microsphere (MS) model. The ratio of radioactivity (count/pixel/min) in the conventional early SPECT image (taken 25-55 min after IMP injection) to that in the "super-early" image for each brain region negatively correlated with regional CBF value obtained with the "super-early" MS method. This indicates that wash-out of IMP from the regions with higher CBF is faster than that from the regions with lower CBF and that CBF values are underestimated with the conventional MS method in regions with higher CBF. Regional CBF was quantitatively measured with the "super-early" MS method and the ARG method, a recently developed method based on two-compartment model. The mean cortical CBF was 52.5 +/- 7.0 (ml/100 g/min, mean +/- SD) with the "super-early" MS method and 47.5 +/- 3.3 with the ARG method. The CBF values obtained with the "super-early" MS method agreed with those previously reported with positron emission tomography. Since the MS method is theoretically the simplest model, the "super-early" MS method can be applied various disorders of the central nervous system where the behavior of IMP is not fully understood.

Prevalence of goiter and urinary iodine excretion levels in children around Chernobyl

The prevalence of goiter among children living in areas affected by the Chernobyl accident was investigated by analysis of data on approximately 120,000 children examined at five medical diagnostic centers in Belarus, Russia, and the Ukraine. Examinations of thyroid gland were conducted with an arch-automatic ultrasonographic instrument at the five centers under the same protocol. The diagnosis of goiter was established when the thyroid volume exceeded a limit calculated from age, height, and body weight of a child. A considerable variation by region was noted in the prevalence of goiter. Highest in the Kiev region, the prevalence in the five regions was 54% in Kiev, 38% in the Zhitomir regions of the Ukraine, 18% in Gomel, 22% in the Mogilev regions of Belarus, and 41% in the Bryansk region of Russia. Urinary iodine content was measured in approximately 5700 children, and an endemic iodine deficient zone was confirmed in the Bryansk, Kiev, and Zhitomir regions. A significant negative correlation was observed between the prevalence of goiter and the median level of urinary iodine content (Spearman's rank correlation coefficient was -0.35, P = 0.025).

Modulation of force during locomotion: differential action of crustacean cardioactive peptide on power-stroke and return- stroke motor neurons

Crustacean cardioactive peptide (CCAP) elicited expression of the motor pattern that drives coordinated swimmeret beating in crayfish and modulated this pattern in a dose-dependent manner. In each ganglion that innervates swimmerets, neurons with CCAP-like immunoreactivity sent processes to the lateral neuropils, which contain branches of swimmeret motor neurons and the local pattern-generating circuits. CCAP affected each of the four functional groups of motor neurons, power-stroke excitors (PSE), return-stroke excitors (RSE), power-stroke inhibitors (PSI), and return-stroke inhibitors (RSI), that innervate each swimmeret. When CCAP was superfused, the membrane potentials of these neurons began to oscillate periodically about their mean potentials. The mean potentials of PSE and RSI neurons depolarized, and some of these neurons began to fire during each depolarization. Both intensity and durations of PSE bursts increased significantly. The mean potentials of RSE and PSI neurons hyperpolarized, and these neurons were less likely to fire during each depolarization. When CCAP was superfused in a low Ca2+ saline that blocked chemical transmission, these changes in mean potential persisted, but the periodic oscillations disappeared. These results are evidence that CCAP acts at two levels: activation of local premotor circuits and direct modulation of swimmeret motor neurons. The action on motor neurons is differential; PSEs and RSIs are excited, but RSEs and PSIs are inhibited. The consequences of this selectivity are to increase intensity of bursts of impulses that excite power-stroke muscles.

Abnormal cerebral perfusion in chronic methamphetamine abusers: a study using 99MTc-HMPAO and SPECT

1. Cerebral blood flow of nine methamphetamine abusers with technetium-99m-hexamethylpropyleneamine oxime (HMPAO) and single photon emission computed tomography (SPECT) as well as morphological examination with magnetic resonance imaging (MRI) were investigated. 2. Six of these subjects exhibited multiple focal perfusion deficits in cerebral cortices without abnormalities in MRI including cerebral atrophy and/or infarctions. 3. Cerebral perfusion deficits were detected in methamphetamine abusers even after a long abstinence period, suggesting that vascular changes were irreversible to some degree. 4. HMPAO SPECT study appeared to be sensitive to the detection of cerebral perfusion abnormalities in drug abusers.

Induction of acquired immunity in rats that have eliminated intracranial gliosarcoma cells by the expression of herpes simplex virus-thymidine kinase gene and ganciclovir administration

We examined a possible antitumor response against 9L rat gliosarcoma cells induced by the expression of the herpes simplex virus-thymidine kinase (HSV-TK) gene and the ganciclovir (GCV) system. Based on the amount of the major histocompatibility complex (MHC) class I antigens expressed on 9L cells transduced by the HSV-TK gene (9L/HSV-TK) we selected two clones (clones H and L), which represent high and low expressors of class I antigens, respectively. By means of serial magnetic resonance imaging we followed the change of tumor volumes of each clone in syngeneic rats, and found that the intracranial tumor growth was inversely correlated with the expression of MHC class I antigens, although in vitro growths of the clones remained unchanged. Moreover, histological examination revealed significant lymphocyte infiltration in the 9L/HSV-TK tumor of high MHC expression but not in the wild-type tumor. The therapeutic effect of GCV on them was not different, but we observed a prolonged survival of the rats which had eliminated 9L/HSV-TK clone L tumors by the treatment of GCV and were rechallenged with the same cells compared with the survival of naive rats inoculated with clone L cells. These data collectively suggest that the immune response operates even in the brain previously described as an immunologically privileged site.

Measurement of acetylcholinesterase by positron emission tomography in the brains of healthy controls and patients with Alzheimer's disease

BACKGROUND

Acetylcholinesterase activity, a marker for degeneration of the central cholinergic system, has consistently been reported, in necropsy brain studies, to be reduced in the cerebral cortex of patients with Alzheimer's disease. We have shown regional acetylcholinesterase activity in vivo in rodent and primate brains with radioactive acetylcholine analogues. In the present study, we used one of the analogues to map acetylcholinesterase activity in the brains of living people.

METHODS

Positron emission tomography (PET) and a radiolabelled acetylcholine analogue with high hydrolytic specificity to acetylcholinesterase [11C]N-methyl-4-piperidyl acetate (MP4A), was used in eight elderly healthy controls and five patients with Alzheimer's disease who had mild dementia. All participants were given an intravenous injection of [11C]MP4A and then sequential patterns of radioactivity in various brain regions were obtained by PET. Time courses of [11C]MP4A concentration in arterial blood were also measured to obtain an input function. A three-compartment model was used to estimate regional acetylcholinesterase activity in the brain.

FINDINGS

The estimated acetylcholinesterase distribution in the brain of the control participants agreed with the acetylcholinesterase distribution at necropsy. All patients with Alzheimer's disease had multiple cortical regions with a reduced estimated acetylcholinesterase activity in comparison with control participants. The reduction was more pronounced in the parietotemporal cortex, with an average reduction rate of 31% in temporal and 38% in parietal cortex, and less pronounced in other cortical lesions (19% in frontal, 24% in occipital, and 20% in sensorimotor cortex). Each patient was found to have at least two cortical regions with significantly reduced acetylcholinesterase activity.

INTERPRETATION

The method we describe for non-invasive in-vivo detection of regional acetylcholinesterase changes in the living human brain that is feasible for biochemical assessment of Alzheimer's disease.

Novel point mutation in the uroporphyrinogen III synthase gene causes congenital erythropoietic porphyria of a Japanese family

The molecular basis of the uroporphyrinogen III synthase (UROIIIS) deficiency was investigated in a member of a Japanese family. This defect in heme biosynthesis is responsible for a rare autosomal recessive disease: congenital erythropoietic porphyria (CEP) or Günther's disease. The patient was homozygous for a novel missense mutation: a G to T transition of nucleotide 7 that predicted a valine to phenylalanine substitution at residue 3 (V3F). The parents were heterozygous for the same mutation. The loss of UROIIIS activity was verified by an in vitro assay system. The corresponding mutated protein was expressed in Escherichia coli and no residual activity was observed. Further studies are needed to determine whether the mutations of the UROIIIS gene (UROS) have a specific profile in Japan compared to European or American countries.

p53 induced by ionizing radiation mediates DNA end-jointing activity, but not apoptosis of thyroid cells

To understand the effects of ionizing radiation on thyroid cells, we investigated the role of p53 in mediating apoptosis and in DNA repair following in vivo and in vitro irradiation of thyroid cells. In vitro exposure of human thyroid cells to ionizing radiation of up to 5-8 Gy failed to induce apoptosis in primary cells. The same results were obtained when the thyroid gland was irradiated in the intact rat. To explore the mechanism of failure of the wild-type p53 in inducing apoptosis in thyroid cells, we investigated the expression of apoptosis-related genes, bax, bcl-2 and fas/APO-1 following irradiation or induction of temperature-sensitive p53. The expression of Bax, Bcl-2 and Fas/APO-1 in human primary cultured thyroid cells did not change after irradiation. To further confirm the results, we established a clonal cell line (tsFRO) in which a temperature sensitive p53 (Val138) expression vector was stably transfected to a thyroid carcinoma cell line lacking endogenous p53. Incubation of tsFRO cells at the permissive temperature for three days, however, did not induce apoptosis although G1 arrest was noted. Although enhanced expression of the bax mRNA level was observed, the expression of Bax, Bcl-2 and Fas/APO-1 protein did not change by shifting tsFRO cells to permissive temperature as well as irradiated primary cells. Furthermore, DNA end-jointing ability was examined by transfection of linearized luciferase plasmid into tsFRO cells. Increased luciferase activity occurred when the cells were cultured at the permissive temperature, indicating that the wild-type p53 enhances DNA end-jointing activity. Our results indicate that the wild-type p53 does not lead to apoptosis but facilitates DNA end-jointing in thyroid cells. These results may reflect specific responses in thyroid cells following irradiation.

Prediction of drug cytotoxicity in 9L rat brain tumor by using flow cytometry with a deoxyribonucleic acid-binding dye

OBJECTIVE

Flow cytometry (FCM) with a deoxyribonucleic acid (DNA)-binding dye, propidium iodide, provides a rapid and quantitative method to detect apoptotic cell death. This technique was used to examine the sensitivity of tumor cells to anticancer agents, as a novel test of chemosensitivity in vitro.

METHODS

The in vitro chemosensitivity of 9L gliosarcoma cells to a panel of anticancer agents (cisplatin, nimustine, adriamycin, cyclophosphamide, vincristine, 5-fluorouracil, and methotrexate) was investigated by both FCM, yielding DNA histograms, and a microtiter tetrazolium test, measuring cellular metabolism. Clinically achievable concentrations of the agents were used for the analysis of DNA histograms and proliferation of 9L cells in vitro. Rats intracranially inoculated with 9L cells were treated with the agents, and tumor masses were visually monitored by using magnetic resonance imaging with gadolinium-diethylenetriaminepentaacetic acid enhancement.

RESULTS

The cytotoxic effect of anticancer agents examined by the microtiter tetrazolium test correlated with a decreased G0/G1 peak in the DNA histograms. Serial FCM analysis showed that the decrease in the G0/G1 peak was subsequently accompanied by increased hypodiploid areas, suggesting DNA fragmentation induced by the agents. The in vitro chemosensitivity test and cell proliferation examination showed that all agents except cisplatin were effective. Growth retardation of inoculated brain tumors and prolonged survival of inoculated rats were observed with treatment with the anticancer agents, except cisplatin.

CONCLUSION

The present study shows that FCM analysis with a DNA-binding dye can detect DNA damage induced by anticancer agents, and it suggests that this technique is a novel method to test chemosensitivity in vitro.

Positive correlations between cerebral protein synthesis rates and deep sleep in Macaca mulatta

Local rates of cerebral protein synthesis (ICPSleu) were determined with the autoradiographic L-[1-14C]leucine method in seven awake and seven asleep, adult rhesus monkeys conditioned to sleep in a restraining chair in a darkened, ventilated chamber while EEG, EOG, and EMG were monitored. Prior to the period of measurement all animals slept for 1-4 h. Controls were awakened after at least one period of rapid-eye-movement (REM) sleep. Experimental animals were allowed to remain asleep, and they exhibited non-REM sleep for 71-99% of the experimental period. Statistically significant differences in ICPSleu between control and experimental animals were found in four of the 57 regions of brain examined, but these effects may have occurred by chance. In the sleeping animals, however, correlations between ICPSleu and percent time in deep sleep were positive in all regions and were statistically significant (P < or = 0.05) in 35 of the regions. When time in deep sleep was weighted for the integrated specific activity of leucine in grey matter, positive correlations were statistically significant (P < or = 0.05) in 18 regions in the experimental animals. These results suggest that rates of protein synthesis are increased in many regions of the brain during deep sleep compared with light sleep.

High-resolution immuno-scanning electron microscopy using a non-coating method: study of herpes simplex virus glycoproteins on the surface of virus particles and infected cells

The expression of two glycoproteins, i.e. glycoprotein C (gC) and glycoprotein D (gD), of herpes simplex virus type 1 (HSV-1) on the surface of extracellular particles of this virus was examined by immuno-scanning electron microscopy. Scanning electron microscopy specimens of infected cells immuno-labelled against the glycoproteins with colloidal gold particles were prepared by a conventional coating and a non-coating method. Surface ultrastructure of infected cells and gold particles were observed more clearly with specimens prepared by the non-coating method. The appearance of virus particles in association with glycoprotein expression on these particles and on the surface of infected cells was then studied. Progeny virus particles began to appear 6 h after infection, increased in number as the infection proceeded, and covered most of the cell surface by 16 h. Six to 24 h after the infection, the labelling density for each glycoprotein on virus particles remained constant. The labelling density for gD was always higher than that for gC. The patch-like distribution of gold-labelling against gD was often detected on infected cell monolayers at the exponential and late stage of one cycle of virus growth. The labelling density for gD on virus particles was the highest on these produced in Vero and L-929 cells, moderate in MRC-5, BHK-21 and FL cells, and the lowest in HEp-2 cells.

Expression and regulation of G protein-coupled receptor kinase 5 and beta-arrestin-1 in rat thyroid FRTL5 cells

G protein-coupled receptor kinases (GRKs) and arrestins are implicated in homologous desensitization of G protein-coupled receptors. We have recently demonstrated that among six GRKs so far identified, GRK5 is the isoform predominantly expressed in the thyroid and appears to be mainly involved in homologous desensitization of thyrotropin receptor (TSHR) in FRTL5 cells. To further understand the molecular mechanisms of the TSHR desensitization, the expression and regulation of GRKs and arrestins together with those of the TSHR were examined in FRTL5 cells. Northern blot analysis of total RNA from FRTL5 cells with the available rat GRK cDNAs (GRK4, 5, and 6) as probes showed that only GRK5 mRNAs of approximately 3, 8, and 10 kilo bases (kb) in length were detectable. When probed with rat beta-arrestin-1 and beta-arrestin-2 cDNAs, beta-arrestin-1 mRNAs of approximately 7.5 and 2.5 kb long, but no (or possibly faint) approximately 2.4 kb beta-arrestin-2 mRNA, were observed, suggesting that in the thyroid, beta-arrestins appear to be predominantly of beta-arrestin-1 isoform. In studies on TSH-regulation of GRK5, beta-arrestin-1 and TSHR mRNAs, steady-state levels of GRK5 and TSHR mRNAs were 3- to 4-fold lower in the cells grown in the medium with TSH than in those without TSH, while betaarrestin-1 mRNA levels were unchanged. Downregulation of GRK5 and TSHR mRNAs by TSH was further confirmed by dose- and time-dependent experiments. Incubation with 1mM 8BrcAMP, a cAMP analog, for 24h fully reproduced this TSH inhibitory effect. A decrease in GRK5 protein by TSH was also confirmed with Western blot analysis. In summary, these data together with our previous data suggested that GRK5 and beta-arrestin-1 seem to be the isoforms predominantly expressed in the thyroid, and they appear to play a pivotal role in TSHR homologous desensitization. We also demonstrated TSH downregulation of GRKS, but not beta-arrestin-1, expression. Further studies will be necessary to elucidate how these phenomena are linked to thyroid pathophysiology.

Parathyroid hormone-related peptide in synovial fluid and disease activity of rheumatoid arthritis

To understand the clinical role of parathyroid hormone-related peptide (PTHrP) in rheumatoid arthritis (RA), we analysed the circulatory and synovial fluid (SF) concentrations of the N- and C-terminal regions of PTHrP (N- and C-PTHrP) in RA (n = 38), osteoarthritis (OA, n = 45) and control (n = 11) subjects. The SF level of C-PTHrP was markedly higher in RA compared with control and OA groups, while no differences in circulatory C-PTHrP were present among the three groups. In contrast, the SF level of N-PTHrP was marginally higher in OA patients. C-PTHrP levels in SF correlated significantly with CRP, ESR and SF IL-1 receptor antagonist. To identify the mechanism of elevated PTHrP levels in SF, immunohistochemistry and in situ hybridization of synovial membrane (SM) were performed in each subject. Overexpression of PTHrP was identified in the sublining cells within papillary proliferated SM of RA patients only. Our results indicate that C-PTHrP produced from SM into SF reflects the disease activity in RA.

Epitope-tagging of a functional thyrotropin receptor: detection of the native receptor on intact cells

To facilitate immunological detection of thyrotropin receptor (TSHR), we inserted a c-myc epitope within the unique, 50 amino acid segment of the ectodomain (TSHRmyc). When stably expressed in 293 human embryonal kidney (HEK) cells, TSHRmyc demonstrated high affinity TSH binding and the ability to produce cAMP in response to TSH. Binding of the myc monoclonal antibody 9E10 to 293-TSHRmyc cells could be detected with [125I] anti-mouse IgG. No competition was observed between TSH and 9E10 binding to 293-TSHRmyc. Immunoprecipitation by 9E10 of TSHRmyc revealed TSHR forms of approximately 95 and approximately 100 kDa. Endoglycosidase digestion identified the approximately 95 kDa species as the single chain precursor with high mannose carbohydrate. The approximately 100 kDa single chain receptor contained mature, complex carbohydrate. No smaller species of TSHR subunits or proteolytic fragments was observed. Again TSH did not inhibit immunoprecipitation of TSHRmyc by 9E10. These data demonstrate that the normally functioning c-myc epitope-tagged TSHR can be detected directly and in native form with a readily available anti-myc 9E10 and without the need for prior affinity capture. Lack of competition between 9E10 and TSH suggests that at least part of the 50 amino acid segment in TSHR ectodomain is not a TSH binding site. This epitope-tagged TSHR will be valuable for further studies on the synthesis and trafficking of TSHR.

Evaluation of the bystander effect in experimental brain tumors bearing herpes simplex virus-thymidine kinase gene by serial magnetic resonance imaging

Antitumor effects of herpes simplex virus-thymidine kinase (HSV-tk) gene transfer followed by ganciclovir (GCV) administration were studied by serial magnetic resonance imaging (MRI) with reference to the bystander effect. Mixed populations of 9L-gliosarcoma cells transduced with the HSV-tk gene (TK cells) and wild-type 9L cells were implanted into the brain of syngeneic Fisher rats at various ratios (total cell number, 10(5) cells; percentage of TK cells, 100%, 25%, 10%, or 0%). Rats were treated with GCV (30 mg/kg per day) or saline for 14 days and tumor masses were visually monitored using MRI. All of the saline-treated rats (regardless of TK cell percentage) and GCV-treated rats inoculated with 0% TK cells died between day 19 and day 31 (mean survival, 22.9 days) due to progressive tumor growth. The GCV-treated rats inoculated with more than 10% of TK cells lived significantly longer than the saline-treated rats (p < 0.01). The mean survivals of GCV-treated groups were 50.7, 70.0, and longer than 100 days for 10%, 25%, and 100% TK cells, respectively. MRI study revealed that reduction in tumor size and disappearance of tumor were observed in the GCV-treated rats inoculated with 10% or 25% TK cells. Complete regression of the tumor was, however, observed only in the rats implanted with 100% TK cells. The present results show that the bystander effect is clearly observed in vivo in a TK percentage-dependent manner, and a population of more than 25% of TK-positive cells is required for complete tumor elimination.

Osteogenic action of parathyroid hormone-related peptide (1-141) in rat ROS cells

To examine the autocrine/paracrine effect of parathyroid hormone-related peptide (PTHrP) on osteoblast function, the entire coding region of rat PTHrP (1-141) cDNA inserted into the expression vector was stably transfected into the rat clonal strain of the osteoblast-like cell, ROS 17/2.8, and established stable transfectants. Using the PTHrP-overexpressing ROS cells (ROS/PLP/6), we analyzed in vitro cell characterization and in vivo osteogenic properties. As expected, overexpression of endogenous PTHrP in vitro induced PTH/PTHrP receptor down-regulation confirmed by Northern blots, receptor binding assays, and functional analysis. The established transfectants indicated a decreased growth rate compared with the original non-transfected ROS 17/2.8. Although cAMP production induced by exogenous PTH was suppressed in ROS/PLP/6, the stimulatory effects of forskolin and chorela toxin showed no significant difference between the original ROS 17/2.8 and transfected cells, but the in vivo osteogenic properties were histologically potentiated in transfectants with increased bone matrix and acceleration of mineralization within tumors. The levels of osteocalcin and osteopontin mRNAs were also increased in transfectants. The down-regulated in vitro PTH/PTHrP receptor mRNA was restored in in vivo tumor tissues. Our study provides clear evidence that the in vivo osteogenic function in ROS cells is potentiated by PTHrP, through an autocrine/paracrine mode of action.

Photoelectron holography of the si(001) surface

Three-dimensional images of the near-surface atom arrangement were calculated from two-dimensional photoelectron diffraction data by several imaging algorithms: (i) a basic method with a Fourier transformation at one kinetic energy over k space, considering the phase factor due to the path-length difference; (ii) energy summation of the above results; (iii) Fourier transformation within small k-space windows; and (iv) their combinations. Atomic images produced by these methods from the experimental Si 2p photoelectron diffraction patterns of an Si(001) surface are compared with the crystal geometry. The results show that the energy-summed small-window method, called SWEEP, gives the best images.

In vivo bystander effect in the intracranial model with rat glioma cells reflects the clonal difference of HSV-TK positive cells

We have investigated clonal variations on the in vivo bystander effect of herpes simplex virus-thymidine kinase (HSV-TK)/ganciclovir (GCV) system, using an intracranial tumor model with 9L rat gliosarcoma cells. For this purpose, we established three 9L clones transduced with HSV-TK gene (9L-TK), each of which had similar TK activity but showed different tumor growth rate in vivo. The use of GCV in vitro confirmed previous reports that the bystander effect was manifest in a confluent culture condition, but not in a low cell density condition. In contrast, the therapeutic benefit of the in vivo bystander effect varied among each 9L-TK clone, and had a positive correlation with the in vivo growth rate of the clone. Thus, the bystander effect seems to reflect the growth rate of TK-positive cells, and these data raise a crucial point for applying the bystander effect to clinical trials.

Parathyroid hormone-related protein (PTHrP) action in rat articular chondrocytes: comparison of PTH(1-34), PTHrP(1-34), PTHrP(1-141), PTHrP(100-114) and antisense oligonucleotides against PTHrP

Parathyroid hormone-related protein (PTHrP) is thought to be an important autocrine/paracrine factor for chondrocyte metabolism since mice lacking the PTHrP gene exhibit abnormal cartilage development. To determine the biological role of PTHrP in chondrocytes, we first compared the agonist potency of human (h) PTHrP(1-34) with hPTH(1-34) in cultured rat articular chondrocytes. Neither hPTHrP(1-34) nor hPTH(1-34) altered basal DNA synthesis, but attenuated the stimulatory effect of transforming growth factor beta (TGF-beta). Both agents suppressed the expression of alpha(1) type II collagen mRNA in a dose-response fashion with the same potency. In addition, the action of exogenously added hPTHrP(1-34) and hPTH(1-34) on intracellular cAMP and [Ca2+]i levels was similar. We next compared the effect of PTHrP within its entire amino acid sequence (1-141). With regard to thymidine incorporation, alpha(1) type II collagen gene expression and accumulation of cAMP and [Ca2+]i level, there was no significant difference between hPTHrP(1-34) and hPTHrP(1-141). PTHrP C-terminal (100-114) did not show any function. To further investigate PTHrP function, intracellular PTHrP translation was inhibited by a transgene of antisense oligonucleotides against PTHrP. Antisense oligonucleotides decreased PTHrP mRNA translation, specifically inhibited DNA synthesis in control as well as TGF-beta-treated chondrocytes and enhanced alpha(1) type II collagen mRNA expression in TGF-beta-treated chondrocytes. These results suggest that there is no significant difference between exogenously added hPTH(1-34), hPTHrP(1-34) and PTHrP(1-141) with regard to the biological action of these agents, including cell growth, differentiation and second messenger pathway. However, the result of DNA synthesis in the antisense PTHrP-inhibition study suggests that intracellular PTHrP may have an as yet unknown biological role, in addition to a classical PTH/PTHrP receptor-mediated function in the rat articular chondrocyte.

The effect of steroid on thallium-201 uptake by malignant gliomas

In order to assess the effect of steroid on thallium-201 uptake by glioma, 201Tl single-photon emission tomography was performed before and after steroid administration in four patients with recurrent malignant glioma. After steroid administration the 201Tl index, expressed as the ratio of 201Tl uptake in the tumour to that in the contralateral cerebral hemisphere, was 0.77+/-0.11 of the value before steroid (mean+/-SD: P<0.05 by paired t test). The 201Tl index has been used as a possible indicator for the differentiation of malignant gliomas from relatively benign tumours or radiation necrosis. The present results indicate that the effect of steroid has to be taken into account when semi-quantitative analysis, e.g. by means of the 201Tl index, is used in patients with brain tumours.

Association of p53 gene mutation with decreased chemosensitivity in human malignant gliomas

Loss of p53 function is involved in tumorigenesis of various human cancers, but the relation between mutation of the p53 tumor-suppressor gene and the chemo- and radiosensitivity of tumors remains unclear. Mutated p53 gene in malignant glioma is often associated with progression and recurrence of malignancy, and these events are closely linked with increased resistance to both chemotherapy and radiation. We have examined the status of the p53 gene in malignant gliomas obtained from 34 patients (glioblastoma: 29 cases, anaplastic astrocytomas: 5 cases). The chemosensitivities of these specimens using 28 kinds of anti-cancer agents were determined using an in vitro assay system. Overall, 12 mutated cases of p53 gene were found in malignant glioma samples. The mean numbers of effective agents were 0.58 for the tumor samples with p53 mutations and 5.00 for tumors without mutations. Our data indicate that p53 gene mutation predisposes to decreased cell killing via chemotherapy in malignant gliomas.

Effect of volatile anesthetics with and without verapamil on intracellular activity in vascular smooth muscle

BACKGROUND

Although halothane and isoflurane inhibit receptor agonist-induced smooth muscle contraction by inhibiting Ca2+ influx via the L-type voltage-dependent Ca2+ channels, their effects on pharmacomechanical coupling remained to be clarified. The intracellular action of both anesthetics was studied during agonist-induced contractions using the Ca2+ channel blocker verapamil.

METHODS

Isolated spiral strips of rat thoracic aorta with endothelium removed were suspended for isometric tension recordings in physiologic salt solution. Cytosolic concentration of Ca2+ ([Ca2+]i) was measured concomitantly using fura-2-Ca2+ fluorescence. Muscle contraction was evoked by the receptor agonists with 30 nm norepinephrine or 10 microM prostaglandin F2 alpha (PGF2 alpha), followed by exposure to halothane, at 0%, 1%, 2%, and 3% or isoflurane, at 2% and 4%. The effects of the anesthetics were compared with those of 0.1-1 microM verapamil (n = 8 for each condition). To clarify the intracellular action of the volatile anesthetics on agonist-induced contractions, this procedure was repeated for the anesthetics only in the presence of 1 microM verapamil (n = 8 for each condition). The effects of both anesthetics were also examined in nonreceptor-mediated contractions evoked with a 1-microM dose of the protein kinase C activator, 12-deoxyphorbol 13-isobutylate, which increases the Ca2+ sensitivity of the contractile elements (n = 8 for each).

RESULTS

Halothane, isoflurane, and verapamil suppressed norepinephrine-and PGF2 alpha-induced increases in muscle tension and [Ca2+]i in a concentration-dependent manner. The Ca2+-tension regression lines suggested that the volatile anesthetics reduced Ca2+ sensitivity of the contractile elements during PGF2 alpha-induced contraction. Pretreatment of the muscle strip with verapamil revealed that halothane and isoflurane released Ca2+ during norepinephrine-induced contraction and that [Ca2+]i-tension relationship was modulated during PGF2 alpha-induced contractions. Halothane at 2% and 3% and isoflurane at 4% suppressed 12-deoxyphorbol 13-isobutylate-induced increases in muscle tension, whereas they enhanced increases in [Ca2+]i, indicating that both anesthetics suppressed Ca2+ sensitivity during 12-deoxyphorbol 13-isobutylate-induced contraction.

CONCLUSIONS

Verapamil pretreatment unmasked the intracellular action of the anesthetics. Halothane and isoflurane influenced pharmacomechanical coupling during agonist-induced contraction.

Low incidence of the stimulatory G protein alpha-subunit mutations in autonomously functioning thyroid adenomas in Japan

Point mutations of the alpha-subunit of the stimulatory G protein (Gs alpha) (termed gsp) and the TSH receptor, leading to constitutive elevation of intracellular cAMP contents, have recently been described in autonomously functioning thyroid adenomas. Since we have recently found a clear difference in the incidence of such gain-of-function mutations of the TSH receptor between Japan and Europe, the present study was designed to evaluate the incidence of gsp mutations in a series of autonomously functioning thyroid adenomas in a Japanese population. Thirty-eight autonomously functioning thyroid adenomas were employed in the present study. Genomic DNA was extracted from archival formalin-fixed, paraffin-embedded tissue specimens. Exons 8 and 9 of the Gs alpha gene were examined for activating mutations at codons 201 and 227 by single-strand conformation polymorphism (SSCP) and nucleotide sequencing. Both exons 8 and 9 were successfully amplified in 28 of 38 samples by polymerase chain reaction. Of these only one sample for exon 9 displayed a distinct migration pattern in SSCP analysis, in which a point mutation of a G to C transversion was identified by nucleotide sequencing, resulting in substitution of His (CAC) for Gln (CAG) at codon 227. The wild-type sequence of exon 9 in 10 randomly selected samples with an identical migration pattern in SSCP analysis suggests that underestimation of the incidence of gsp mutations is unlikely in our work. In conclusion, the present data, together with our previous data on the TSH receptor, suggest that oncogenic mutations of the Gs alpha as well as the TSH receptor do not seem to play a major role in tumorigenesis of autonomously functioning thyroid adenomas in Japan.

A novel point mutation in congenital erythropoietic porphyria in two members of Japanese family

The molecular basis of the uroporphyrinogen III synthase (UROIIIS) deficiency was investigated in two members of a Japanese family. This defect in heme biosynthesis is responsible for a rare autosomal recessive disease: congenital erythropoietic porphyria (CEP) or Gnther's disease. The first patient was homoallelic for a novel missense mutation: a T to C transition of nucleotide 634 that predicted a serine to proline substitution at residue 212 (S212P). The second patient appeared heteroallelic, carrying the same missense mutation and a nonsense mutation: a C to T change at nucleotide 745, resulting in a premature stop at codon 249, instead of a glutamine (Q249X). The corresponding mutated proteins were expressed in Escherichia coli and no residual activity was observed. A family study was also performed to determine the carrier status.

Involvement of G protein-coupled receptor kinase 5 in homologous desensitization of the thyrotropin receptor

Homologous desensitization of G protein-coupled receptors involves agonist-dependent phosphorylation of receptors by G protein-coupled receptor kinases (GRKs). To identify GRK(s) that play a role in homologous desensitization of the thyrotropin (TSH) receptor, thyroid cDNA was amplified by polymerase chain reaction using degenerate oligonucleotide primers from highly conserved regions in GRK family. GRK5 is found in the predominant isoform expressed in the thyroid. Rat GRK5 cDNA was then isolated, which encodes a 590-amino acid protein with 95% homology to human and bovine homologs. Northern blot identified GRK5 mRNA of approximately 3, 8, and 10 kilobases with highest expression levels in lung > heart, kidney, colon > thyroid. In functional studies using a normal rat thyroid FRTL5 cells, overexpression of GRK5 by transfecting the plasmid capable of expressing the sense GRK5 RNA suppressed basal cAMP levels and augmented the extent of TSH receptor desensitization, whereas suppression of endogenous GRK5 expression by transfecting the antisense GRK5 construct increased basal cAMP levels and attenuated the extent of receptor desensitization. Although exogenously overexpressed GRK6 also enhanced TSH receptor desensitization, we conclude that GRK5, the predominant GRK isoform in the thyroid, appears to be mainly involved in homologous desensitization of the TSH receptor.

Brain acetylcholinesterase activity: validation of a PET tracer in a rat model of Alzheimer's disease

We developed three radioactive acetylcholine analogs--N[14C]methyl-4-piperidyl acetate ([14C]MP4A), propionate ([14C]MP4P) and isobutyrate ([14C]MP4IB)--as radiotracers for measuring brain acetylcholinesterase (AchE) activity in vivo. The principle of our method is that the lipophilic analog diffuses into the brain where it is metabolized by AchE to produce a hydrophilic metabolite, which is trapped at the site of its production. The purpose of this study was to examine whether the tracers would have the sensitivity needed for early diagnosis of Alzheimer' disease using rats with a unilateral lesion in the nucleus basalis magnocellularis (NBM), an animal model of the cholinergic deficit in Alzheimer's disease.

METHODS

Rats with a unilateral NBM lesion were prepared, and the N[14C]methyl-4-piperidyl esters and N-Isopropyl-p-[123I]iodoamphetamine([123I]IMP were injected intravenously 30 and 2 min, respectively, before the rats were killed. Uptake of 14C and 123I and AchE activity in the lesioned and unlesioned (control) sides of the cortex were measured simultaneously.

RESULTS

The NBM lesion showed reduced cortical AchE activity by 30%-50%, with no side-to-side differences in [123I]MP uptake. Autoradiographic studies showed that uptake of 14C from [14C]MP4A and [14C]MP4P was significantly lower in the lesioned than unlesioned side of the cortex, which agreed well with the AchE histochemical staining patterns. Tissue dissection studies showed different uptake changes for the three compounds when AchE activity in the lesioned side of the cortex was reduced by 50%: 14C uptake from [14C]MP4P, [14C]MP4A and [14C]MP4IB was reduced by 27%, 21% and 7.3%, respectively. Theoretical analysis of the observed sensitivities of the tracers in relation to their in vitro enzymatic properties indicated that tracer sensitivity was highly dependent on the enzymatic hydrolysis rate of the tracer.

CONCLUSION

The [14C]MP4A and [14C]MP4P esters had sufficient sensitivity to enable AchE activity changes in the rat cortex of less than 50% to be detected, indicating that the present method is applicable to PET diagnosis of Alzheimer's disease.

[Epidural buprenorphine does not improve diaphragmatic function after upper abdominal surgery]

We investigated the effect of epidural buprenorphine on diaphragmatic function using respiratory inductive plethysmography (RIP) in seven healthy patients after upper abdominal surgery. After surgery, changes of rib cage contribution to tidal volume (%RC) increased significantly from 25.3 +/- 7.3 (mean +/- SD) to 50.7 +/- 14.8% (P < 0.05). After the injection of epidural buprenorphine, visual analogue scale (VAS) score decreased significantly from 8.3 to 3.3 (P < 0.05). But, %RC was unchanged compared to the value before the injection. These results indicate that pain relief by epidural buprenorphine does not improve diaphragmatic function after upper abdominal surgery.

Time courses of changes in cerebral blood flow and blood-brain barrier integrity by focal proton radiation in the rat

In order to know the pathophysiological mechanisms underlying radiation brain injury, cerebral blood flow and blood-brain barrier integrity were studied using N-isopropyl-p-[123l]iodoamphetamine (IMP) and [14C]-alpha-aminoisobutyric acid (AIB), respectively, in the rat focal proton radiation model (a single dose of 30 or 60 Gy radiation with 70 MeV proton beams). One, 2, 4, and 5.5 months after irradiation, [123l]IMP and [14C]AIB were intravenously injected and uptake of IMP and AIB in the cerebral cortex, striatum, hippocampus, and thalamus was measured. Significant decreases in IMP uptake were observed in the cerebral cortex and thalamus of the irradiated side at 4 and 5.5 months after 60 Gy irradiation; the effects at 5.5 months were more prominent than those at 4 months. AIB uptake markedly increased in all the brain regions of the irradiated side at 5.5 months after 60 Gy irradiation, and at 4 months, only in the hippocampus. The results suggest that there are dose- and time-dependent responses in radiation effects and regional differences in tissue vulnerability to radiation. Proton focal radiation model appears to be a useful model for studies of radiation brain injury in small animals such as rats.

Quantifying brain tumor blood flow by the microsphere model with N-isopropyl-p-[123I]iodoamphetamine super-early SPECT

Regional cerebral blood flow was quantitatively measured in 6 patients with brain tumor by the microsphere model with N-isopropyl-p-[123I]iodoamphetamine (IMP) "super-early" single photon emission computed tomography (SPECT) images obtained 4-6 min after IMP injection with a three-head rotating gamma camera. The ratio of radioactivities (counts/pixel/min) in the "early" SPECT images (taken 25-55 min after IMP injection) to the "super-early" images of the brain tumors was 1.47 +/- 0.13 (mean +/- SD, n = 6), which was significantly lower than the ratio in the normal cerebral cortices (1.93 +/- 0.25) (p < 0.01). This indicates faster clearance of IMP from the tumor tissue than that from the normal brain tissue. Blood flow values for the brain tumors obtained by the microsphere model based on the "super-early" SPECT images were 39.3 +/- 12.4 ml/100 g/ min, which was similar to the blood flow values for normal gray matter and in agreement with previous studies with positron emission tomography.

Histopathological characteristics of childhood thyroid cancer in Gomel, Belarus

We reviewed histopathologically 19 cases of childhood thyroid cancer occurring between 1991 and 1994 among 14,396 screening subjects in Gomel, Republic of Belarus, the region most severely radio-contaminated by the Chernobyl nuclear power plant accident in 1986. The patients were 13 girls and 6 boys with a mean age of 10.6 years. The mean age at the time of the accident was 3.2 years. Mean tumor diameter was 16 mm, and all cases were papillary carcinoma with various amounts of solid component. Psammoma bodies and stromal fibrosis were encountered to some extent in almost all cases. The tumors were highly prone to local invasion and regional lymph-node metastasis. No morphological evidence for radiation-induced cancer was obtained in these cases. 137Cs levels were relatively high in the patients' bodies and in the soil at the places of domicile. However, there was no dose-response relationship between cancer prevalence and radioactivity. These facts suggest that the incidence of aggressive pediatric thyroid cancer is extremely high in Gomel, where most of the children were exposed to a low level of radioactivity over a long time after the accident. At present, however, no definite conclusion can be drawn on the relationship between cancer occurrence and radioactive contamination.

Antisense inhibition of parathyroid hormone-related peptide gene expression reduces malignant pituitary tumor progression and metastases in the rat

A newly established metastatic rat pituitary tumor (mGH3) possesses a malignant phenotype that is invasive and hypervascular compared with the original GH3 tumors. mGH3 cells exhibit anchorage independence and expression of elevated levels of parathyroid hormone-related peptide (PTHrP) in vitro. To clarify the role of PTHrP in the development of the malignant phenotype, tumor cells were treated with phosphorothioate antisense PTHrP oligonucleotide. Treatment with antisense PTHrP resulted in a scattering phenomenon in the colony formation assay but did not inhibit cell growth in vitro. Inoculation of mGH3 cells in the cerebral ventricle resulted in a rapid growth of tumor cells within 3 weeks and dissemination throughout the entire ventricular system. Although treatment with sense or mismatched PTHrP oligonucleotide did not influence the subsequent tumor growth, the in vivo coinjection and injection of antisense PTHrP 1 week after tumor cell implantation into the right lateral ventricle markedly reduced tumor size and suppressed metastasis formation. The survival rate of mGH3 tumor-injected rats was prolonged by antisense PTHrP therapy. Our results demonstrated the biological involvement of PTHrP in malignant phenotype in rat pituitary tumors, suggesting that antisense PTHrP may provide a novel antimetastatic therapy for malignant somatotroph tumors.

Adaptation to high-salt stress in Saccharomyces cerevisiae is regulated by Ca2+/calmodulin-dependent phosphoprotein phosphatase (calcineurin) and cAMP-dependent protein kinase

Ca2+/calmodulin-dependent phosphoprotein phosphatase (calcineurin, PP2B) of Saccharomyces cerevisiae is implicated in adaptation to high-salt conditions. Calcineurin mediates high salt-induced expression of the ENA1/PMR2 gene encoding the P-type ATPase, which is suggested to be involved in Na+ efflux. We identified the PDE1 gene encoding the low-affinity cAMP phosphodiesterase as a multicopy suppressor of the Li(+)- and Na(+)-sensitive calcineurin null mutant, suggesting that cAMP is a negative regulator of adaptation to high-salt stress. Genetic analysis indicated that calcineurin and cAMP act antagonistically in a common pathway for adaptation. The bcy1 disruption, which leads to constitutive cAMP-dependent protein kinase (PKA) activity inhibited high NaCl-induced expression of the ENA1/PMR2 gene, caused an elevation of the intracellular Na+ level and a growth defect in high-NaCl medium, all of which were analogous to the defects of a calcineurin mutant. A reduced cAMP level resulting from multiple copies of the PDE1 gene caused increased expression of the ENA1/PMR2 gene in response to high NaCl. We propose a model for the regulation of cation homeostasis, in which calcineurin antagonizes PKA to activate transcription of the ENA1/PMR2 gene in response to high-salt conditions.