[Development of new in vitro chemosensitivity test using collagen gel droplet embedded culture and its clinical usefulness]

We developed a new in vitro assay for chemosensitivity test using collagen gel droplet embedded culture and image analysis. In this in vitro assay, we successfully minimized the cancer cell number required for culture to approximately 3-10 x 10(3) cells for each 30 microliters collagen gel droplet, obtained the sufficient growth of cancer cells using serum-free medium while suppressing the growth of fibroblastic cells, and measured the volume of cancer cells by eliminating the contaminating fibroblastic cells by an image processing technique. Anticancer effects of the in vitro assay showed a very good correlation with those of in vivo nude mouse assay using human cancer cell lines. The success rates of the in vitro assay for 141 surgical specimens of primary lung cancers and for 65 of primary breast cancers were 89 and 80%, respectively. The accumulated in vitro assay response rates of MMC, CDDP, VDS and VP-16 for primary lung cancers and of MMC, 5-FU and ADR for primary breast cancers were similar to the respective clinical response rates. These results suggest that this in vitro chemosensitivity test may be practically useful for clinical applications.

Regulation of neurotensin receptor mRNA expression by the receptor antagonist SR 48692 in the rat midbrain dopaminergic neurons

In this study, we demonstrated that the tyrosine hydroxylase-like immuno-reactive (possibly dopaminergic) neurons express neurotensin receptor mRNA in the rat substantia nigra and in the ventral tegmental area. Additionally, 2 weeks treatment with the neurotensin receptor antagonist SR 48692 increased mRNA levels in the substantia nigra. These data suggest that neurotensin receptor expression in the perikarya and in the terminal regions of dopaminergic neurons is regulated by its endogenous agonist in vivo.

A novel analog of TRH, YM14673, causes a decrease in brain TRH receptors in vitro

Biochemical mechanisms by which analogs of thyrotropin-releasing hormone (TRH) produce their potent neuropharmacological actions on the brain remain ill-defined. We tested effects of YM14673, a novel analog of TRH, on TRH receptors in rat brains in vitro. No significant binding of [3H]YM14673 to brain plasma membranes occurred. In contrast, preincubation of membranes with YM14673 caused dose-dependent decreases in TRH binding. This was not due to competition for TRH binding sites or existence of metabolites of YM14673. Preincubation with DN1417 (an another TRH analog), cyclo(His-Pro) or methionine-enkephalin did not affect the binding. Affections of YM14673 on TRH binding were observed when cerebral cortical membranes were studied; those were not seen in membranes prepared from hypothalamus, striatum, midbrain, hippocampus, or pons-medulla. The present data indicate that YM14673 exerts its characteristic neuro-pharmacological functions through interacting with TRH binding sites in the brain.

Normal age-related conversion of bone marrow in the mandible: MR imaging findings

OBJECTIVE

The mandible is one of the most common sites for osteomyelitis and other marrow-based diseases. Therefore, knowledge of the normal patterns of marrow distribution could help evaluate marrow-based diseases. The purpose of this study was to assess the age-related normal sequence of conversion from hematopoietic to fatty marrow in the mandible as depicted on MR images.

SUBJECTS AND METHODS

We prospectively reviewed T1-weighted MR images of the mandible for the distribution of hematopoietic and fatty marrow. Forty-five subjects 4 months to 25 years old with no known marrow abnormality were examined with the spin-echo technique. Marrow conversion was assessed in the condyle, ramus, angle, and body of the mandible using visual grading based on homogeneity, signal intensity, and a signal-intensity ratio determined by the intensities of the surrounding subcutaneous fat and air.

RESULTS

Conversion of hematopoietic to fatty marrow occurred first in the mandibular body, followed by the angle, ramus, and finally the condyle. The marrow in the region distal to the ramus had almost fully converted to fatty marrow by the third decade of life, but the remaining regions contained some hematopoietic marrow. Further substantiating these results, the signal-intensity ratio increased up to about 90% in the angle and 70% in the ramus by the age of 10 years and then leveled off. On the other hand, the signal-intensity ratio in the condyle reached 60% by age 15 and remained unchanged for the following 10 years.

CONCLUSION

The normal age-related conversion from hematopoietic to fatty marrow in the mandible follows a well-defined sequence, first seen in the mental region early in childhood, then in the body, the ramus, and finally the condyle.

Neuronal localization of CD38 antigen in the human brain

CD38 is a lymphocyte differentiation antigen which is involved in the cyclic ADP-ribose-mediated second messenger system. We provide immunochemical and immunohistochemical evidence for the expression of CD38 in the adult human brain. We used six polyclonal antibodies against synthetic CD38 polypeptides, in addition to four monoclonal antibodies already available. Brain CD38 was detectable by Western blotting after immunoaffinity purification of the brain extracts. Immunoperoxidase staining localized CD38 immunoreactivity to the perikarya and dendrites of many neurons, such as the cerebellar Purkinje cells, implying that CD38 is involved in the signal transduction within the central nervous system neurons.

Alteration of cataleptic responses induced by dopamine receptor antagonists after chronic cocaine administration in mice

The influence of chronic treatment of mice with cocaine, an indirect dopamine receptor agonist, on the cataleptic effects of R-(+)-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin- 7ol hydrochloride (SCH23390), a dopamine D1 receptor antagonist, or haloperidol, mainly a dopamine D2 receptor antagonist, was investigated. Mice were given cocaine (10 mg/kg s.c.) once every other day for 7 (4 injections), 15 (8 injections) or 21 (11 injections) days. The cataleptic effects of SCH23390 (0.3 mg/kg i.p.) were significantly reduced when it was given 1-7 days after the last dose of a 7- or 15-day pretreatment course of cocaine. When SCH23390 was given 14-21 days after the cocaine the cataleptic effect was increased in the 15-day, but not the 7-day, cocaine-pretreated mice. However, after a 21-day treatment with cocaine, a challenge dose of SCH 23390 given 1-3 days thereafter produced a decreased cataleptic response, but an increased response after 7-21 days. The cataleptic effects of haloperidol (o.3 mg/kg i.p.) were reduced when it was given 1-7 days after the last dose of a 7-day pretreatment, but increased 1-3 days after that of a 15-day pretreatment with cocaine (10 mg/kg s.c.) The pretreatment with cocaine for 21 days did not affect the haloperidol catalepsy during a 1- to 3-day withdrawal period. However, haloperidol catalepsy was decreased only 7 days, then reversed 14 days and gradually increased 21 days after the last injection of a 15- or 21-day pretreatment course of cocaine. These results suggest that chronic treatment with the indirect dopamine receptor agonist, cocaine, caused supersensitivity of dopamine D1 receptors (a decrease in SCH23390 catalepsy) during the early withdrawal period and subsensitivity (an increase in SCH23390 catalepsy) after a longer period of withdrawal. It was apparent that the longer the period and the higher the dose of pretreatment with cocaine, the less were the alterations in initial responses and the greater were the alterations in subsequent responses to the dopamine D1 receptor antagonists.

Pharmacological characterization of SR 48692 sensitive neurotensin receptor in human pancreatic cancer cells, MIA PaCa-2

Previously, one type of human neurotensin receptor has been molecularly cloned. Recently, it has been proposed that a subtype of neurotensin receptor exists, which is not sensitive to newly synthesized neurotensin receptor antagonist SR 48692. In this study, we characterize the pharmacological properties of neurotensin receptor expressed in human pancreatic cancer cells, MIA PaCa-2. In binding studies with [3H]neurotensin, the data fit a model for a single population of high-affinity binding sites that are competitively antagonized by SR 48692. The rank order of the equilibrium dissociation rate constants for neurotensin(8-13), neurotensin, neuromedin N, [Ala11] neurotensin(8-13), and SR 48692 were similar to those found with the molecularly cloned human neurotensin receptors. Additionally, the intracellular calcium mobilization and the growth of MIA PaCa-2 cells induced by neurotensin receptor agonist were completely inhibited by SR 48692. In conclusion, our results showed that MIA PaCa-2 cells express functional and SR 48692-sensitive-type neurotensin receptors. It is suggested that the neurotensin receptor antagonist SR 48692 may be useful in the treatment of pancreatic cancers that possess this type of neurotensin receptor.

[A case of sudden death during postoperative Holter ECG examination in a patient who experienced intraoperative cardiac arrest]

We report a case of postoperative sudden death during Holter-ECG examination in a 62-yr-old male, who experienced intraoperative cardiac arrest possibly due to myocardial ischemia. Although the patient recovered from intraoperative event without any neurological sequelae, he suffered from spontaneous ventricular tachycardia following mild ST segment depression that led to cardiac arrest on the 58th postoperative day. Precise mechanism of sudden death was not clear because coronary angiography or autopsy was not performed. However, the postoperative Holter-ECG revealed frequent episodes of silent 0.5-1.0 mm ST segment depression during tachycardia which had not been observed in the preoperative 12-lead ECG. Thus a likely explanation would be that the patient had the undetected coronary artery disease with frequent episodes of silent ischemia and finally was led to the fatal arrhythmia. In this case, so called "stunned myocardium" following repeated silent ischemia may have also contributed to the life-threatening arrhythmias. This case suggests that even mild ST depression might lead to life-threatening arrhythmias in the patients with silent ischemia. Adequate preoperative evaluation and careful perioperative observation are necessary for these patients.

[A case of inspiratory unidirectional value malfunction detected by an abnormal capnogram pattern]

We report a case of substantial rebreathing which occurred during the thoracoscopic bulla resection despite a normal FICO2 reading on capnogram. Early detection of inspiratory unidirectional valve malfunction as the cause of the rebreathing was only possible by careful observation of the capnogram pattern. During the course of one lung anesthesia, a rising end-tidal CO2 concentration (FETCO2) and a change in the pattern of the capnogram were observed. However, the lowest FICO2 value in the late phase of inspiration stayed below the alarm limit setting of rebreathing. For this reason, the capnograph failed to identify the beginning of inspiration and perceived the high FICO2 value in early inspiration as part of expiratory plateau. In case of the inspiratory valve malfunction, it is possible that analysis of the capnogram reveals underestimated FICO2.

Epidermal growth factor prevents oxygen-triggered apoptosis and induces sustained signalling in cultured rat cerebral cortical neurons

Epidermal growth factor (EGF), a conventional mitogenic factor, acts as a neurotrophic factor on several types of neurons in the central nervous system. We found that EGF prevented the death of rat cerebral cortical neurons cultured in a 50% oxygen atmosphere. This high-oxygen-triggered cell death showed features of apoptotic cell death, which was blocked by inhibitors of RNA or protein synthesis. EGF prevented the oxygen-induced death of the cultured cortical neurons in a dose-dependent manner. Basic fibroblast growth factor (bFGF) also prevented this cell death, although there was no apparent additive effect of EGF and bFGF. Among the cultured cortical neurons, we observed neurons possessing the EGF receptor and cells expressing c-Fos protein in response to EGF. The cortical neurons were cultured in the presence of cytosine arabinoside, and the number of glial fibrillary acidic protein-positive astroglial cells was < 0.5% of that of the corresponding microtubule-associated protein 2-positive neurons. Therefore, the effect of EGF on the cultured cortical neurons is thought to be due to a direct action. We also examined EGF-induced signalling in the cultured cortical neurons. We found that EGF induced the sustained tyrosine phosphorylation of the EGF receptor and sustained the activation of mitogen-activated protein kinase in the cultured cortical neurons. We suggest that EGF may exert the survival effect through the prolonged activation of the EGF signalling.

Lissencephaly gene product. Localization in the central nervous system and loss of immunoreactivity in Miller-Dieker syndrome

The Miller-Dieker syndrome, a disorder of neuronal migration, is caused by deletions of chromosome 17p13.3. Recently, a gene on 17p13.3, named LIS-1, was identified as the causative gene for this cerebral anomaly. Here we immunochemically and immunohistochemically localized the gene product, LIS-1 protein, among control normal subjects and patients with Miller-Dieker syndrome, using specific antibodies raised against synthetic peptide fragments of LIS-1 protein. Western blot analyses identified LIS-1 protein as a 45-kd, heparin-binding protein abundant in the cytosolic fraction. The protein was restricted to the central nervous system and detectable in brains of controls of all ages, from the early fetal to adult period. Immunostaining demonstrated the widespread distribution of LIS-1 protein in the brain and spinal cord of controls and a loss of immunoreactivity in individuals with Miller-Dieker syndrome. These results are consistent with the notion that a deficiency of LIS-1 protein is the direct cause of the brain malformation and that the protein plays a critical role in neuronal migration.

Cysteine protease of the nematode Nippostrongylus brasiliensis preferentially evokes an IgE/IgG1 antibody response in rats

Some cysteine proteases such as papain and those of mites and schistosomes have potent allergenic properties. To clarify the allergenicity of nematode cysteine proteases, the enzyme was purified from the intestinal nematode Nippostrongylus brasiliensis using cation exchange chromatography and gel filtration chromatography. The purified protease, of 16 kD and pI 8.5, showed maximum enzyme activity at pH 5.5 and substrate preference for Z-Phe-Arg-MCA. The specific inhibitors of cysteine protease leupeptin, iodoacetic acid, and E-64, completely suppressed the activity, indicating that the purified enzyme belongs to the cysteine protease family. Cysteine protease activity was found not only in somatic extract, but also in the excretory-secretory (ES) product of the nematode. When anti-cysteine protease immunoglobulin isotypes were examined in sera from rats infected with N. brasiliensis, a high level of IgG1 and a lower level of IgE antibody were detected. Depletion of IgG antibodies from the sera using protein G affinity columns resulted in a marked increase in reactivity of anti-cysteine protease IgE with the antigen, possibly due to the removal of competing IgG antibodies. In contrast to IgE and IgG1, production of anti-cysteine protease IgG2a was negligible. These results indicate that the nematode cysteine protease preferentially evokes an IgE/IgG1 antibody response.

Enhancement by cyclo-oxygenase inhibitors of platelet-activating factor production in thapsigargin-stimulated macrophages

1. Thapsigargin stimulated the accumulation of cell-associated platelet-activating factor (PAF) and extracellular prostaglandin E2 (PGE2) in rat peritoneal macrophages. PAF in the conditioned medium was less than the detectable amount. To obtain further insight into the mechanism of PAF accumulation, the role of PGE2 in PAF accumulation was investigated. 2. When macrophages were incubated in medium containing thapsigargin (30 ng ml(-1), 46.1 nM) and cyclo-oxygenase inhibitors such as indomethacin, naproxen or ibuprofen, the PAF content of the cells at 10 min was increased in a concentration-dependent manner in accordance with inhibition of PGE2 production. The stimulation by thapsigargin, cyclo-oxygenase inhibitors did not increase PAF accumulation. 3. In thapsigargin-stimulated macrophages, when PGE2(10(-7) M) was added to the medium, the cyclo-oxygenase inhibitor-induced stimulation of PAF accumulation at 10 min was markedly inhibited. 4. The accumulation of PAF induced by thapsigargin alone at 10 min was inhibited by exogenous PGE2 (10(-8) and 10(-7) M), or arachidonic acid (10(-6) and 10(-5) M) in accordance with the increase in PGE2 production. 5. The accumulation of PAF induced by thapsigargin alone or by thapsigargin and indomethacin (10(-6) M) was inhibited by dibutyryl cyclic AMP. 6. These results indicate that the concurrently produced PGE2 in thapsigargin-stimulated macrophages down-regulates PAF accumulation by increasing intracellular cyclic AMP levels, and that cyclo-oxygenase inhibitors increase PAF accumulation by inhibiting PGE2 production.

Spastic tetraplegia as an initial manifestation of familial Alzheimer's disease

Two sisters with familial Alzheimer's disease developed spastic gait disturbance as an initial manifestation. Their gait disturbance progressed gradually, followed by dementia a few years later. Post-mortem examination of one of the patients disclosed degeneration of the thalamus and corticospinal tract in addition to numerous senile plaques and neurofibrillary tangles in the neocortex, both of which were confirmed by immunohistochemistry. This is the first report in which clinicopathological evaluation is sufficient to establish a new variant of Alzheimer's disease presenting initially as spastic tetraplegia.

[Diagnosis and prognosis of elderly patients with coronary artery disease: assessment with dipyridamole thallium imaging]

Noninvasive evaluation of coronary artery disease is difficult in elderly patients because of their limited exercise-capacity. The diagnostic and prognostic value of dipyridamole perfusion scintigraphy was assessed in 147 patients aged 65 years and older. All patients underwent coronary angiography. Initially, 32 patients had percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG). The other 115 patients were first treated medically and followed for a mean of 29 +/- 22 months. Nine patients (7.9%) had cardiac events including cardiac death and coronary intervention (PTCA or CABG) during the follow-up. Dipyridamole perfusion scintigraphy was performed safely in all patients, whereas treadmill exercise testing could not be adequately performed in 24 patients, 18 of whom had multivessel disease. Multiple regression analysis showed that: fixed defect and reversible defect were powerful detectors of coronary lesions (p = 0.0001, p = 0.0027, respectively), all patients with fixed disease and 94% of patients with only reversible defect had significant coronary lesion; Diffuse slow washout and ST depression were statistically significant for detecting multivessel coronary lesions in patients with fixed disease (p = 0.0001, p = 0.017, respectively), the sensitivity and specificity of diffuse slow washout and/or ST depression for detecting multivessel coronary lesions ware 85% and 74%, respectively, and ST depression was statistically significant for detecting multivessel coronary lesions (p = 0.0002) in patients with only reversible defect, the sensitivity and specificity of ST depression were 88% and 64%, respectively. Cox survival analysis identified diffuse slow washout as the best predictor of future cardiac events among the scintigraphic variables.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of scatter correction on quantification of myocardial SPECT and application to dual-energy acquisition using triple-energy window method]

Triple-energy window (TEW) method is a simple and practical approach for correcting Compton scatter in single-photon emission tracer studies. The fraction of scatter correction, with a point source or 30 ml-syringe placed under the camera, was measured by the TEW method. The scatter fraction was 55% for 201Tl, 29% for 99mTc, 57% for 123I. Composite energy spectra were generated and separated by the TEW method. Combination of 99mTc and 201Tl was separated well, and 201Tl and 123I were separated within an error of 10%; whereas asymmetric photopeak energy window was necessary for separating 123I and 99mTc. By applying this method to myocardial SPECT study, the effect of scatter elimination was investigated in each myocardial wall by polar may and profile curve analysis. The effect of scatter was higher in the septum and the inferior wall. The count ratio relative to the anterior wall including scatter was 9% higher in 123I, 7-8% higher in 99mTc and 6% higher in 201Tl. Apparent count loss after scatter correction was 30% for 123I, 13% for 99mTc and 38% for 201Tl. Image contrast, as defined myocardium-to-left ventricular cavity count ratio, improved by scatter correction. Since the influence of Compton scatter was significant in cardiac planar and SPECT studies; the degree of scatter fraction should be kept in mind both in quantification and visual interpretation.

Activation of the thyrotropin-releasing hormone (TRH) receptor by a direct precursor of TRH, TRH-Gly

We studied the mechanism by which thyrotropin-releasing hormone (TRH)-Gly stimulated prolactin and thyrotropin (TSH) secretion in pituitary, using a pituitary mammotropic cell line, GH3 cells, and a cell line stably expressing a human TRH receptor (TRH-R). In GH3 cells expressing endogenous TRH-R, an addition of TRH-Gly evoked an immediate rise of intracellular calcium concentration, indicating that TRH-Gly reacted directly without converting from TRH-Gly to TRH. In order to determine whether this reaction might occur through TRH-R, we established a cell line stably expressing a human TRH-R, by transfecting a human TRH-R cDNA into Chinese hamster ovary cells (CHO cells). In this cell line, 10 nM TRH elevated intracellular calcium significantly; the Kd for MeTRH was 1.7 nM. One micromolar and 100 nM TRH-Gly also elevated intracellular concentration of calcium significantly, but not in CHO cells which were not transfected with the TRH-R cDNA. Competition studies further revealed that TRH-Gly displaced MeTRH binding (IC50, 12 microM). These data indicate that at high concentration, TRH-Gly interacts directly with TRH-R to activate signal transduction pathway, and that release of prolactin and TSH induced by TRH-Gly in vitro may be due, at least in part, to the direct effect of TRH-Gly on the TRH-R.

Dynamic interactions of rabbit liver cytochromes P450IA2 and P450IIB4 with cytochrome b5 and NADPH-cytochrome P450 reductase in proteoliposomes

Purified liver microsomal cytochrome P450IA2 or P450IIB4 was co-reconstituted with cytochrome b5 or NADPH-cytochrome P450 reductase in phosphatidylcholine-phosphatidylethanolamine-phosphatidylserine vesicles at a lipid to P450 weight ratio of 2 by cholate dialysis procedures. The proteoliposomes catalyzed drug oxidation. Rotational diffusion of cytochrome P450 was measured by observing the decay of absorption anisotropy, r(t), after photolysis of the heme.CO complex. Analysis of r(t) was based on a "rotation-about-membrane normal" model. The absorption anisotropy decayed within 1 ms to a time-independent value, r3. Different rotational mobility for the two cytochrome P450s was observed. Though 20% of cytochrome P450IA2 was immobile, all cytochrome P450IIB4 molecules were rotating. The rotational relaxation time, phi, of the mobile population was 237 microseconds for cytochrome P450IA2 and 160 microseconds for cytochrome P450IIB4. The two cytochrome P450s have shown very different interactions with cytochrome b5 and NADPH-cytochrome P450 reductase. By the presence of the redox partner, the mobile population of cytochrome P450IA2 was increased significantly from 80% to 96% (plus cytochrome b5) and to 89% (plus NADPH-cytochrome P450 reductase) due to dissociation of P450 oligomers. On the other hand, the mobility of cytochrome P450IIB4 was not considerably affected by the presence of cytochrome b5 or NADPH-cytochrome P450 reductase as judged by little difference in phi and r3, keeping the mobile population of 100%. These results imply that cytochrome P450IA2 forms a transient association with cytochrome b5 and NADPH-cytochrome P450 reductase.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycosylated human recombinant interleukin-1 alpha, neo interleukin-1 alpha, with D-mannose dimer exhibits selective activities in vivo

To investigate the effect of carbohydrate-introduction on IL-1 activity, especially in vivo, and to develop IL-1 with less deleterious effects, recombinant human IL-1 alpha was coupled with mannose dimer, alpha-D-Man-1-6-D-Man [Man2 alpha(1-6)] by an acyl azide method. Previous studies demonstrated that the glycosylated IL-1 exhibited reduced activities compared with original IL-1 in all the experiments performed in vitro. In this study, we investigated the in vivo activities of Man2 alpha(1-6)-conjugated IL-1 alpha. The glycosylated IL-1 alpha exhibited very low pyrogenic activity and alpha 1-acid glycoprotein induction compared with untreated IL-1 alpha. Untreated IL-1 alpha increased the serum level of IL-6, but the glycosylated IL-1 alpha did not. However, the glycosylated IL-1 alpha possessed the same potency as untreated IL-1 alpha in reduction of serum levels of glucose and triglyceride and in recovery of peripheral white blood cells in 5-fluorouracil-treated mice. Therefore, glycosylation of IL-1 appeared to be useful for the development of neoIL-1 with selective activity in vivo.

Analysis of molluscum contagiosum virus genomes isolated in Japan

The genomes of 477 Japanese strains of molluscum contagiosum virus (MCV) were analyzed using an in-gel digestion method with the restriction enzyme BamHI, and classified into four types, including a newly detected type (MCV type 4). All type 1 (MCV-1) genomes examined so far in Japan showed a common difference from the genome of the MCV-1 prototype (MCV-1p), the type reported to be most prevalent in Europe. The common markers of the variants of MCV-1 were 24-kbp fusion fragments generated by the loss of a BamHI site between the D2 and F fragments of MCV-1p. These variants of MCV-1 were classified into three groups (MCV-1va, MCV-1vb, MCV-1vc), with the variability among them being due to additions and losses of BamHI sites located in the right terminus and around the E and I fragments of MCV-1va. The restriction map of MCV-4 was generated and lined up with those of the other types. Cross-hybridization analysis revealed that the organization of all types of MCV genomes were essentially colinear. Considerable numbers of BamHI restriction sites were conserved between MCV-2 and 4, indicating a close analogy between them. The overall prevalence of MCV, as shown by the ratios of MCV-1 (MCV-1p):MCV-2:MCV-3:MCV-4, was 436(0):13:24:4. Thus, the molecular epidemiology of MCV in Japan is characterized by the absence of the European prototype of MCV-1, the exclusive occurrence and abundance of variants of MCV-1, a greater prevalence of MCV-3 over MCV-2, and the presence of MCV-4.

Transcriptional down-regulation by epidermal growth factor of TRH receptor mRNA in rat pituitary cells

To gain insight into the mechanism underlying the epidermal growth factor (EGF)-induced changes in responsiveness to TRH and in the numbers of TRH receptors (TRH-Rs) in the pituitary, we investigated the transcriptional regulation by EGF of the TRH-R gene in GH4C1 cells. Northern blot analyses and binding studies revealed that EGF reduced both TRH binding and TRH-R mRNA levels in a dose- and time-dependent manner, while no significant changes were observed in beta-actin mRNA levels. Addition of actinomycin D caused an acute increase in the basal TRH-R mRNA level, and the rate of decrease of the TRH-R mRNA was identical in control and EGF-treated groups, suggesting that the stability of the TRH-R mRNA was not significantly affected in EGF-treated cells. Incubation with cycloheximide also induced an increase in the basal TRH-R mRNA level and completely reversed the EGF-induced reduction of TRH-R mRNA levels. Furthermore, a nuclear run-on assay demonstrated that the rate of transcription of the TRH-R gene was significantly inhibited in cells treated with EGF. We conclude that (1) EGF decreases the expression of the TRH-R mRNA largely by reducing its rate of transcription, and this action requires the synthesis of new proteins, and (2) inhibitors of protein and RNA synthesis cause a significant increase in the basal TRH-R mRNA level, suggesting that there may be a short-lived protein suppressing the TRH-R mRNA level in the pituitary.

Expression of recombinant human thyrotropin receptor in myeloma cells

Starting with a previously isolated cDNA for human thyrotropin receptor (TSHR), we established a transformed myeloma cell line, SP56, which expresses human TSHR on its cell surface. Binding analysis showed that SP56 bears 1.1 x 10(5) TSHR per cell with a Kd of 2.2 x 10(-10) M. Using the purified cellular membrane, we established a TSH binding inhibition immunoglobulin (TBII) assay for autoantibodies against TSHR. We compared it with the TBII assay utilizing porcine thyroid membranes expressing porcine TSHR, which has been widely used for TBII assay, by using 96 serum samples from patients with autoimmune thyroid disease and normal individuals. Our TBII assay was more sensitive than the one using porcine TSHR: of 38 sera of patients which were judged negative for autoantibodies to TSHR (TBII value below 10%) by the latter assay, 28 were positive (above 20%) in our assay. By using a perfusion culture system, we obtained as many as 3 x 10(10) SP56 cells, from which 3,450 mg protein of the membrane could be purified; this is sufficient for 15,000 assays. The results indicate that the membrane of the myeloma cell line SP56 is more suitable for use in the TBII assay than the porcine thyroid membrane, in terms of sensitivity to autoantibodies against TSHR in human sera.

The effects of a carotid-jugular fistula on cerebral blood flow in the cat: an experimental study in the chronic period

The purpose of the present study was to investigate the effects of feline carotid-jugular fistula (Spetzler's model) on cerebral blood flow at 8 weeks after creation of the fistula. Using laser-Doppler flowmetry, cortical cerebral blood flow (CBF) on the fistula side was measured in 10 cats, Occlusion of the fistula showed no cortical CBF changes in 6 animals, but transient increases in 4. CO2 reactivity in the closed fistula was preserved. No neurological or histological abnormalities were recognized. These findings suggested that cerebral hemodynamic changes due to Spetzler's CJ fistula model are minimal even in the chronic period after fistulization. Therefore, creation of another experimental arterio-venous fistula model is mandatory for the investigation of hemodynamic changes following resection of a cerebral arteriovenous malformation.