Infusions of pressor agents selectively attenuate depressor responses to ACh in anesthetized dogs

In dogs anesthetized with pentobarbital sodium (30 mg/kg iv), infusions of phenylephrine (PE; 1-3 micrograms.kg-1.min-1 iv for 30 min and longer) caused sustained elevations in blood pressure and suppressed depressor responses to acetylcholine (ACh; 1 microgram/kg iv) in a dose- and time-dependent manner. The dose-response curve for ACh (0.01-100 micrograms/kg iv)-induced depressor responses was shifted to the right by approximately 80-fold after an intravenous infusion of PE (3 micrograms.kg-1.min-1) for 120 min. Similar suppression was observed when infusions of methoxamine (5 micrograms.kg-1.min-1 iv), norepinephrine (3 micrograms.kg-1.min-1 iv under blockade of beta-adrenoceptors), or angiotensin II (0.3 micrograms.kg-1.min-1 iv) were carried out. However, in dogs treated with prazosin (1 mg/kg iv) or hydralazine (1 mg/kg iv) to prevent elevations in blood pressure over the baseline level, PE (3 micrograms.kg-1.min-1 iv) failed to attenuate depressor responses to ACh. The suppression observed after PE infusion was specific to ACh-induced depressor responses; i.e., no suppression was observed on the depressor responses to other drugs, such as histamine, sodium nitroprusside, carbachol, and methacholine. Furthermore, neostigmine (bolus injection of 30 microgram/kg iv followed by an infusion of 15 micrograms.kg-1.h-1 iv) greatly diminished the suppressive effect of PE. Except for a slight increase in acetylcholinesterase (AChE) activity in renal arterial segments, activities of both AChE and butyryl-cholinesterase in plasma, erythrocytes, and pulmonary and renal arterial segments were unchanged after PE infusion. These results suggest that prolonged elevation in blood pressure and/or vasoconstriction selectively attenuates depressor responses to ACh through accelerated degradation of this material.

Prevention of mammary tumorigenesis in acatalasemic mice by vitamin E supplementation

Adult male and female acatalasemic (C3H/AnLCsbCsb),hypocatalasemic (C3H/AnLCscCsc) and normal mice of C3H strain fed on regular laboratory chow for 15 months showed an increased incidence of spontaneous mammary tumor in the decreasing order of female acatalasemic, male acatalasemic, female hypocatalasemic and male hypocatalasemic mice. Normal mice did not develop mammary tumor. We conducted a prospective study with female acatalasemic mice, which showed the highest incidence of mammary tumor, to examine the preventive effect of vitamin E on mammary tumor. Female acatalasemic mice were fed on vitamin E-deficient (28 animals) and vitamin E-supplemented diet (25 animals) for 29 months. The incidence of mammary tumor in mice given the vitamin E-supplemented diet was 47%, while that in mice given vitamin E-deficient diet was 82% (P < 0.002). Mammary tumors were apparent after 9 months of vitamin E deprivation and after 14 months of vitamin E supplementation. Female normal mice did not develop mammary tumor during a comparable period of time. The mean catalase activity of mammary gland in acatalasemic mice was 18.8% of that in normal mice. The results indicate that vitamin E protects acatalasemic mice against the development of mammary tumor.

Effect of boiled barley-rice-feeding in hypercholesterolemic and normolipemic subjects

Barley contains approximately 10% dietary fiber and is easily cooked with rice, the dominant cereal in Japan, to increase the intake of dietary fiber. This research involved three experiments to examine the influence of barley on blood lipids in human subjects. All subjects received a boiled barley-rice (50/50 w/w mix) supplement two times per day in place of rice for 2 or 4 weeks. In the normolipemic subjects, serum lipids were unaffected by the ingestion of barley for 4 weeks. In twenty hypercholesterolemic men aged 41 +/- 5 years, the ingestion of barley was associated with a significant fall in serum total cholesterol, LDL-cholesterol, phospholipids and LDL and VLDL-lipoproteins. In seven mildly hypercholesterolemic women aged 56 +/- 7 years, a significant improvement of serum lipid profiles was observed. The present study suggests the possibility that the ingestion of barley-rice could lower serum lipids in hypercholesterolemic subjects.

[Autoradiographic studies of oxalate distribution in rat kidney]

BACKGROUND

We performed macro and micro-autoradiographic studies using 14C-oxalate in normal and hyperoxaluric rats in order to elucidate intrarenal distribution of oxalate and to determine where calcium oxalate crystal can be adhere in the kidney.

METHODS

Macro and micro-autoradiographic studies of the kidney in normal rats were carried out at intervals of 15, 30 and 90 min after intravenous administration of 14C-oxalate (37 MBq/kg BW). Hyperoxaluria was induced by vitamin B6 deficient diet. The procedure of macro and micro autoradiography is the same as that in normal rat.

RESULTS

In normal rats, macroautoradiogram showed that the radioactivity of 14C-oxalate exists in the whole kidney, and microautoradiogram identified this radioactivity mainly in the extraluminal space of renal tubules at 15 min. Macro and micro-autoradiograms taken 90 min after the injection showed practically no radioactivity of 14C-oxalate in the cortex or the medulla, but it was located in the extraluminal space of the papilla. In hyperoxaluric rats, macroautoradiogram showed some spotty accumulations of 14C-oxalate in the inner medulla and papilla. Microautoradiogram revealed that these accumulations are mainly seen in the extraluminal space.

CONCLUSION

These results indicate that in normal rats the injected 14C-oxalate remains in the renal papilla, especially in the extraluminal space, when nearly all oxalate was excreted by urine, and in hyperoxaluric rats 14C-oxalate exists there as calcium oxalate crystal or microlith.

PET analysis of a case of cerebrotendinous xanthomatosis presenting hemiparkinsonism

We describe a 34-year-old Japanese woman presenting gait difficulty and Achilles tendon swelling. The patient was diagnosed as having cerebrotendinous xanthomatosis (CTX) based on the high serum cholestanol level and diminished enzymatic activity of 27-hydroxylase of fibroblasts from her skin. Her clinical presentation was atypical regarding the presence of hemiparkinsonism and absence of apparent cataract, dementia, and cerebellar ataxia. Although MRI studies could not detect any abnormality in the basal ganglia or midbrain, PET analysis using [18F]-6-fluoro-L-dopa revealed reduced uptake of dopamine into the putamen, suggesting the impairment of presynaptic dopaminergic neurons.

A brain uptake study of [1-(11)C]hexanoate in the mouse: the effect of hypoxia, starvation and substrate competition

We evaluated the potential of sodium [1-(11)C]hexanoate (11C-HA) as a radiopharmaceutical with which to assess oxidative metabolism of the brain by PET. 11C-HA, sodium [1-(14)C]acetate and [3H]deoxyglucose were simultaneously injected into mice under control, hypoxic and starving conditions. In the control, the brain uptake of 11C was maximal at 3 min (% ID/g = 2.2-2.5), being twice as high as that of 14C, followed by a gradual clearance. The time-radioactivity curve of 11C was similar to that of 14C. Hypoxia enhanced the brain uptake of 3H, but not of either 11C or 14C. Starvation enhanced the brain uptake of 3H and 11C. The clearance rate of 11C was not significantly affected by either condition. In the control brain at 3 min postinjection of HA, 65% of the total radioactivity was detected as labeled glutamate and glutamine, which was gradually decreased by 47% at 30 min. The brain to blood ratios of 11C-HA at 3 min were significantly reduced by butyrate, hexanoate and octanoate loading but not by that with other monocarboxylic acids or ketone bodies.

Conserved structure and adjacent location of the thrombin receptor and protease-activated receptor 2 genes define a protease-activated receptor gene cluster

BACKGROUND

Thrombin is a serine protease that elicits a variety of cellular responses. Molecular cloning of a thrombin receptor revealed a G protein-coupled receptor that is activated by a novel proteolytic mechanism. Recently, a second protease-activated receptor was discovered and dubbed PAR2. PAR2 is highly related to the thrombin receptor by sequence and, like the thrombin receptor, is activated by cleavage of its amino terminal exodomain. Also like the thrombin receptor, PAR2 can be activated by the hexapeptide corresponding to its tethered ligand sequence independent of receptor cleavage. Thus, functionally, the thrombin receptor and PAR2 constitute a fledgling receptor family that shares a novel proteolytic activation mechanism. To further explore the relatedness of the two known protease-activated receptors and to examine the possibility that a protease-activated gene cluster might exist, we have compared the structure and chromosomal locations of the thrombin receptor and PAR2 genes.

MATERIALS AND METHODS

The genomic structures of the two protease-activated receptor genes were determined by analysis of lambda phage, P1 bacteriophage, and bacterial artificial chromosome (BAC) genomic clones. Chromosomal location was determined with fluorescent in situ hybridization (FISH) on metaphase chromosomes, and the relative distance separating the two genes was evaluated both by means of two-color FISH and analysis of YACs and BACs containing both genes.

RESULTS

Analysis of genomic clones revealed that the two protease-activated receptor genes share a two-exon genomic structure in which the first exon encodes 5'-untranslated sequence and signal peptide, and the second exon encodes the mature receptor protein and 3'-untranslated sequence. The two receptor genes also share a common locus with the two human genes located at 5q13 and the two mouse genes at 13D2, a syntenic region of the mouse genome. These techniques also suggest that the physical distance separating these two genes is less than 100 kb.

CONCLUSIONS

The fact that the thrombin receptor and PAR2 genes share an identical structure and are located within approximately 100 kb of each other in the genome demonstrates that these genes arose from a gene duplication event. These results define a new protease-activated receptor gene cluster in which new family members may be found.

Role of the nondominant hemisphere and undamaged area during word repetition in poststroke aphasics. A PET activation study

BACKGROUND AND PURPOSE

Although the resting regional cerebral blood flow (rCBF) in aphasic patients has been thoroughly investigated with positron emission tomography (PET) and single-photon emission CT, and PET studies in normal subjects have elucidated the functional localization of language processing, little is known about the activation pattern of language processing in aphasic patients.

METHODS

We measured the changes in rCBF during a repetition task (hearing a single word and repeating it aloud) and the resting state using the H2(15)O PET activation technique in 6 normal subjects (mean +/- SD age, 58.3 +/- 8.1 years) and 16 aphasic patients: 10 fluent aphasics (age, 60.3 +/- 12.5 years) and 6 nonfluent aphasics (age, 50.5 +/- 8.3 years).

RESULTS

In normal subjects, the posteroinferofrontal area (PIF) including Broca's area, the posterosuperotemporal area (PST) including Wernicke's area, the rolandic areas, and a few other areas were activated with left side dominance by the repetition task. In the resting state, the rCBF in the left PIF and the left posterotemporal area was reduced in both fluent and nonfluent aphasics. In aphasic patients, the magnitude of activation in the right PIF and PST by the repetition task was greater than in normal subjects. The increase in rCBF during the repetition task in the left PIF correlated with the Western Aphasia Battery score of spontaneous speech in the nonfluent aphasics with a left inferofrontal lesion.

CONCLUSIONS

This study shows the importance in aphasic patients of the mirror regions of the left PIF and PST in the nondominant (right) hemisphere for performing the word repetition task. The results also show the importance for nonfluent aphasic patients of the recruitment of the undamaged PIF for spontaneous speech.

In vitro regeneration of Alnus cremastogyne Burk from epicotyl explants

Multiple shoots were grown from seedling explants of Alnus cremastogyne Burk by a two-stage culture procedure: initiation on WP medium supplemented with 2-8 μ M benzylammopurine(BAP) for 6 weeks, thereafter 3 weeks of subculture(shoot multiplication) on the same medium with 1 μ M BAP. A 5-9 fold multiplication rate was achieved. Type and concentration of sugar used in the multiplication medium were shown to be critical factors for both multiple shoot induction and bud elongation, the optima being 87.5mM glucose and 87.5mM sucrose respectively. After transfer to half-strength WP media either containing indolebutyric acid (IBA) or lacking plant growth regulator, almost all the shoots rooted. However, high rhizogenesis could be achieved only with shoots cultured in rooting medium containing 87.5mM sucrose or 175mM glucose, and shoots from multiplication media containing 87.5mM sucrose. Survival of the plantlets following transfer to vermiculite was 100%.

Unitary current through the inward rectifier K+ channel cloned from rabbit heart--comparison with the native K+ channel

Recently, we have cloned a cDNA for a putative cardiac inward rectifier K+ channel (RBHIK1) from rabbit cardiac muscles. However, it's single channel characteristics have remained unknown. Therefore, we investigated the single channel characteristics of the RBHIK1 channel expressed in Xenopus oocytes by the cell attached patch clamp configuration, and compared them with those of the native Ik1 channel of the freshly-isolated ventricular myocytes under similar temperature conditions. In patch clamp experiments with 145 mmol/l K+ in the pipette at room temperature (20-22 degrees C), both the RBHIK1 currents and the native Ik1 showed a strong inward rectifying property. The single channel conductance of the RBHIK1 channel was 17.8 +/- 0.47 pS (n = 4), and that of the native Ik1 channel was 23.5 +/- 0.29 pS (n = 5). The activities of the cloned channel were sensitive to the putative K+ channel blockers (TEA, Cs+ and Ba2+). The open and closed time histograms at -140 mV could be fitted by a single exponential both in the RBHIK1 channel and the native Ik1 channel. Although the closed-time histogram of the native Ik1 channel was fitted by a sum of two exponential curves, that of the RBHIK1 channel was fitted by a single exponential curve. The sublevel corresponding to two-thirds of the unitary current was observed both in the RBHIK1 channel and the native Ik1, but it was more frequently detected in the RBHIK1 channel. Amplitude histogram constructed at -140mV in the RBHIK1 channel exhibited three peaks, which indicated closed, full-open, and 2/3 sublevel state, respectively. Unitary current was calculated to be 2.5 pA and sublevel of the unitary current was 1.68 pA. These characterization in the single channel activities of the RBHIK1 channel will help to study the molecular regulation of the Ik1 channel in cardiac cells.

Inhibition assay for the binding of biotinylated von Willebrand factor to platelet-bound microtiter wells in the presence of ristocetin or botrocetin

We developed a solid-phase inhibition assay for the binding of biotinylated von Willebrand factor (vWF) to platelet glycoprotein (GP)Ib based on an enzyme-linked immunosorbent assay (ELISA) with platelet-bound microtiter wells. Washed platelets were immobilized onto the microplates via the anti-GPIIb/IIIa monoclonal antibody (mAb) VNR-5. In the presence of an antibiotic ristocetin (1 mg/ml, final) or the snake venom botrocetin (2 micrograms/ml, final), biotinylated vWF bound to the affixed platelets with half-maximal binding occurring at a vWF concentration of approximately 2 micrograms/ml. Several specific inhibitors of the binding of vWF to GPIb abolished the interaction of biotinylated vWF with GPIb in a dose-dependent fashion, with comparable protein concentrations to those seen in the liquid-phase inhibition assay using 125I-vWF. These inhibitors included mAb against vWF (NMC-4), mAb against GPIb (AP-1), and two vWF fragments containing vWF's putative GPIb-binding domain, namely a 39/34-kDa dispase-digested vWF fragment and a recombinant vWF fragment. Thus, this new assay is a convenient alternative to the conventional inhibition assay using 125I-vWF.

Hepatitis C virus infection in patients with clinically diagnosed alcoholic liver diseases

To determine the incidence of hepatitis C virus (HCV) infection in patients with alcoholic liver disease (ALD), serum samples from 252 patients with ALD were tested for anti-HCV and HCV RNA. Serial sera of these patients were collected and stored under optimal conditions to allow exact quantification of HCV RNA. Fifteen patients who visited our hospital during the same period of time with chronic HCV infections served as controls. In those with ALD, anti-HCV and HCV RNA were positive in 55.5% and 41.2%, respectively. Patients with histologically diagnosed chronic hepatitis and hepatocellular carcinoma had much higher prevalence rates of HCV RNA (84% and 100%, respectively) compared to those with fatty liver (4.3%), hepatic fibrosis (10.1%) and alcoholic hepatitis (22.2%) (P < 0.01). Although no difference in serum HCV RNA levels was observed between the patients with both ALD and chronic HCV infection and those with chronic HCV infection alone, HCV RNA levels significantly (10-fold) dropped after abstinence in nearly half of the patients (P < 0.01). These data indicate that HCV infection in patients with ALD promotes progression of liver disease, and abstinence from alcohol is associated with a reduction in serum HCV RNA levels.

[Measurement of serum tissue polypeptide antigen (TPA) in patients with malignant tumor using prolifigen TPA-M "Daiichi" kit]

Serum tissue polypeptide antigen (TPA) was measured using a newly developed Prolifigen TPA-M "Daiichi" kit in 1,236 healthy subjects, 2,867 patients with malignant tumors, and 901 with benign diseases. Because 94.0% of healthy subjects had serum TPA under 70 U/l, the cut-off value was set at 70 U/l. Serum TPA was elevated in more than 50% of patients with head and neck cancer, lung cancer, liver cancer, gallbladder or bile duct cancer, pancreatic cancer, colorectal cancer, ovarian cancer, and prostate cancer. The overall positive rate in malignant tumors was 55.5%. Serum TPA was higher in advanced cancer than in earlier stage cancer, and decreased after the resection of the tumor. The false positive rate in benign diseases was 31.3%. ROC analysis revealed the usefulness of TPA as a tumor marker in many cancers. The correlation coefficient between TPA and CYFRA 21-1, and between TPA and TPSA, was 0.747 and 0.694, respectively. In conclusion, measurement of serum TPA using the new kit is useful in the management of patients with various malignant tumors.

Brain death: MR and MR angiography

SUMMARY

Four patients in whom brain deaths was identified on the basis of neurologic and electroencephalographic findings were examined with MR imaging and MR angiography. MR images showed diffuse swelling of the cerebral gyri and cerebellar cortex, which prolongation of both the T1 and T2 signal (representing hypoxic ischemic brain injury), downward displacement of the diencephalon and the brain stem (central and tonsillar herniation), and loss of flow void in the intracranial portions of both internal carotid arteries. MR angiograms did not show the intracranial vessels above the level of the supraclinoid portion of the internal carotid arteries. MR angiography and MR imaging are noninvasive and reliable methods for use in determining brain death.

Assessment of neuromuscular block at the thumb and great toe using accelography in infants

We assessed neuromuscular block at the thumb and great toe using accelography after the administration of vecuronium in infants. Train-of-four stimuli were simultaneously applied to the ulnar and tibial nerves using cutaneous electrodes. Anaesthesia was maintained with nitrous oxide (66%) in oxygen and sevoflurane (1%). Vecuronium 0.1 mg.kg-1 was used for paralysis and reversed with intravenous neostigmine 0.04 mg.kg-1 with atropine 0.02 mg.kg-1 when the train-of-four ratio on the right great toe returned to 25%. The mean (SD) times from initial administration of vecuronium to completion of maximal block on the thumb and great toe were 78 (21.1) s and 75 (14.3) s, respectively (p > 0.05). The times from maximal block to 25% recovery of twitch height at the thumb and great toe were 46 (9.1) min and 45 (9.0) min, respectively. The reversal time from 25% to 75% of the train-of-four ratio after the administration of neostigmine was 136 (49.1) s. We conclude that neuromuscular monitoring of the great toe in infants may be a suitable alternative when the thumb is inaccessible.

Expression of mRNA encoding neurotrophic factors and its regulation in a hybrid neuronal cell line

In a cultured hybrid neuronal cell line (BIM) which was produced between human neuroblastoma cells (IMR32) and thymidine auxotrophs (B3T) of rat nerve-like cells (B103), the mRNAs encoding ciliary neurotrophic factor (CNTF) and neurotrophins were detected by the polymerase chain reaction method. The conditioned medium of BIM cells enhanced choline acetyltransferase (ChAT) activity in septal neurons and survival of ciliary ganglion neurons. The mRNA expression of CNTF and neurotrophins in BIM cells was differently regulated by the stimulation with cAMP, FGF and retinoic acid. These data suggest multiple regulation and collaboration of neurotrophic factors.

Synthesis and evaluation of 5-HT3 receptor antagonist [11C]KF17643

For imaging CNS 5-HT3 receptors by PET, a high affinity 5-HT3 receptor ligand, endo-8-methyl-8-azabicyclo[3.2.1]oct-3-yl 2-(n-propyloxy)-4-quinolinecarboxylate (KF17643), have been labeled with 11C. N-Methylation of the desmethyl compound with [11C]methyl iodide followed by HPLC separation produced [11C]KF17643 with the decay-corrected radiochemical yield of 19-28%, the specific activity of 7.5-49 GBq/mumol and the radiochemical purity of > 99% at 35-40 min from EOB. After i.v. injection of [11C]KF17643 into mice, it was taken by the brain at a high level and was stable for metabolism, but no sign for the 5-HT3 receptor selectivity was found in the brain tissues by the tissue sampling and autoradiography, probably because of large non-specific binding. The [11C]KF17643 was not suitable as a PET ligand for mapping the CNS 5-HT3 receptors.

Reye's syndrome with cortical laminar necrosis: MRI

Serial MRI findings are described in two patients with Reye's syndrome, demonstrating diffuse cortical and white matter changes. In the acute stage, T2-weighted images showed subtle but definite laminar high signal and contrast-enhanced T1-weighted images laminar enhancement, along the entire cerebral cortex bilaterally. In the chronic stage, unenhanced T1-weighted images showed diffuse cortical laminar high signal. These characteristic MRI features seemed very similar to those of laminar cortical necrosis in hypoxic brain damage. MRI also displayed delayed white matter changes with cerebral atrophy.

[Classification of patterns of nocturnal penile tumescence with continuous monitoring of penile rigidity: analysis of various factors affecting erection]

In 43 men who required further examination of erectile function, we analyzed the relationship between the various factors including hormone levels, penile blood pressure index (PBPI), shape of the arterial wave, erection period after prostaglandin E1 injection and dynamic cavernosography/metry, as well as the patterns of nocturnal penile tumescence (NPT) with rigidity. Normal, dissociation, short episode, low amplitude and flat trace patterns, which were classified by Kaneko, were observed in 11, 8, 11, 2 and 11 men, respectively. Uncoupling was not observed in any men. There were no differences in the levels of prolactin and LH among the 6 patterns. A high FSH level was seen in men with a flat trace pattern; a low level of free testosterone ( < 12.2 pg/ml) was seen in men with dissociation, low amplitude and flat trace patterns, and low PBPI ( < 0.75) in men with flat trace pattern; and an arteriosclerotic shape of the arterial wave was seen in men with short episode and flat trace patterns. Each erection period immediately after prostaglandin E1 injection in men with dissociation, short episode, low amplitude and flat trace was shorter compared with cases with a normal pattern. Venoocclusive dysfunction was observed in 5 men with a dissociation pattern and 6 men with a flat trace pattern. In conclusion, an integral analysis of pattern of NPT with rigidity and other examinations are useful for differentiating organic impotence from psychogenic impotence and for accurately diagnosing pathophysiological disorders of organic impotence and underlying diseases.

[Successful aorto-coronary bypass grafting and concomitant left ventricular myotomy-myectomy in a patient with coronary artery disease associated with hypertrophic obstructive cardiomyopathy]

A 65-year-old man complained chest oppression at rest and dizziness. Echocardiography showed subaortic stenosis with outflow gradient of 100 mmHg, although interventricular septal thickness was only 12 mm and left ventricular posterior wall thickness was 11 mm, and mild mitral regurgitation. Selective coronary angiography demonstrated 90% stenosis in left main truncus, 50% stenosis in first diagonal branch, and hypoplastic right coronary artery. Emergent coronary artery revasculization concomitant with left ventricular myotomy myectomy was performed. Immediately after weaning off the cardiopulmonary pump, IABP was employed for cardiac assistance, because of residual left ventricular outflow pressure gradient, which was provoked by cathecholamine and amyl nitrite. He was discharged in 1 month in NYHA class I. Echocardiography 3 months after operation showed no residual outflow pressure gradient, no systolic anterior motion of mitral anterior leaflet, and mild approximately mitral regurgitation. Careful operative management, including myocardial protection and avoiding perforation of ventricular septum and postoperative medical care are mandatory to this group of patients. This case is the first successful coronary artery bypass grafting and concomitant left ventricular myotomy-myectomy reported in Japan.

Evaluation of current sterility tests for human live viral vaccines

Current sterility tests for human viral vaccines were evaluated. A total of 43 lots of bulk suspension of live viral vaccines (measles, mumps, rubella and oral poliomyelitis) produced by six manufacturers in Japan were evaluated for bacteriostatic and mycoplasmastatic activities. Some of them showed fairly high bacteriostatic and mycoplasmastatic activities, due to antibiotics added during vaccine production. It was concluded that the current sterility test for mycoplasmas is not reliable to detect viable mycoplasmas in live viral vaccines.

Hemorrhage and abnormal veins in acoustic neurinoma: MR findings

We reviewed the MR imaging findings of 57 acoustic neurinomas which were verified at surgery or diagnosed on the basis of neuroradiological and neurootological data. Two uncommon MR findings of acoustic neurinoma were found. First, hypointense areas were observed on T2-weighted images in five of the 12 tumors larger than 25 mm in diameter. These hypointense areas represented hemosiderin deposition secondary to occult intratumoral hemorrhage. Second, curvilinear or round signal voids were noted at the periphery of 11 large or medium-sized tumors, and these corresponded to "abnormal veins" seen on angiographic studies.

Participation of gap-junctional cell communication on the adaptive response in human cells induced by low dose of X-rays

To investigate the radioadaptive response of normal cells to low-dose radiation, we irradiated human embryonic (HE) cells and HeLa cells with low-dose X-rays and examined the changes in sensitivity to subsequent high-dose X-irradiation using the trypan blue dye-exclusion test. When HE cells were irradiated by 200 cGy, the growth ratio of the living cells 5 days after the irradiation decreased to 37% of that of the cells which received no X-irradiation. When the cells received a conditioning irradiation of 10-20 cGy 4 h before the irradiation of 200 cGy, the relative growth ratios increased significantly to 45-53%, and a peak was reached at a conditioning dose of 13 cGy to the cells. This conditioning effect was not observed in LeLa cells. When the HE cells were suspended in a Ca2+ ion-free medium or TPA added to the medium while receiving the conditioning irradiation of 13 cGy, the effect of the conditioning dose was not observed. This indicates that normal cells show an adaptive response to low-dose radiation and become more radioresistant. These results suggest that gap junctional intercellular communication may play a role in radioadaptive responses in human cells.

A human friendly reporting and database system for brain PET analysis

We have developed a human friendly reporting and database system for clinical brain PET (Positron Emission Tomography) scans, which enables statistical data analysis on qualitative information obtained from image interpretation. Our system consists of a Brain PET Data (Input) Tool and Report Writing Tool. In the Brain PET Data Tool, findings and interpretations are input by selecting menu icons in a window panel instead of writing a free text. This method of input enables on-line data entry into and update of the database by means of pre-defined consistent words, which facilitates statistical data analysis. The Report Writing Tool generates a one page report of natural English sentences semi-automatically by using the above input information and the patient information obtained from our PET center's main database. It also has a keyword selection function from the report text so that we can save a set of keywords on the database for further analysis. By means of this system, we can store the data related to patient information and visual interpretation of the PET examination while writing clinical reports in daily work. The database files in our system can be accessed by means of commercially available databases. We have used the 4th Dimension database that runs on a Macintosh computer and analyzed 95 cases of 18F-FDG brain PET studies. The results showed high specificity of parietal hypometabolism for Alzheimer's patients.