Suppression of apoptosis by UVB irradiation: survival signaling via PI3-kinase/Akt pathway

UVB irradiation induces apoptosis in several cell types. However, we report here that UVB irradiation prevents induction of apoptosis in cells detached from the extracellular matrix under serum-free conditions. NIH3T3 cells cultured in bovine serum albumin-coated dishes (detached from the extracellular matrix) underwent apoptosis under serum-free conditions, which was inhibited by UVB (<0.1 J/cm(2)) irradiation, keeping suspension conditions, as determined by chromatin condensation and the appearance of a subG1 DNA fraction. Furthermore, UVB irradiation decreased caspase-3/7, -8/6, and -9 activation and eliminated loss of mitochondrial inner transmembrane potential, suggesting suppression upstream of the caspase cascade. Treatment with PI3-kinase inhibitors, wortmannin, and LY294002 partly eliminated the UV-mediated inhibition of cell death and recovered the inhibited caspase-3/7 activity. Phosphorylation of Akt was observed from 15 min after UVB irradiation. These results suggested that UVB irradiation transduced a survival signal via PI3 kinase activation and phosphorylation of Akt, and induced some apoptosis inhibition factors upstream of the caspase cascade.

[2-(O-Phenylalkyl)phenoxy]alkylamines III: Synthesis and selective serotonin-2 receptor binding (2)

A series of 12-(2-phenylethyl)phenoxy]ethylpyrrolidine derivatives were synthesized, and their affinity for serotonin-2 (5-HT2) and dopamine-2 (D2) receptors was examined. Among them, compound 17, (2R,4R)-4-hydroxy-2-[2-[2-[2-(3-methoxyphenyl)ethyl]phenoxylethyl] -1-methylpyrrolidine hydrochloride, showed high 5-HT2 receptor affinity in vitro. This compound was a more potent inhibitor of ex vivo 5-HT-induced platelet aggregation than compound 3, which was previously shown to be more potent than ketanserin (1) and sarpogrelate (2a). However, compound 17 produced gastric irritation in rats. Therefore, we carried out a further derivatization of 17, and compound 45 (R-102444), a lauryl ester prodrug of compound 17, was found to be a promising candidate as an antithrombotic agent. Oral administration of R-102444 produced a marked inhibition of 5-HT-induced ex vivo platelet aggregation, and R-102444 did not cause any gastric irritation. The antiaggregatory effects of R-102444 were more potent than those of sarpogrelate (2a) and its active metabolite, M-1 (2b). In addition, R-102444 exhibited more potent antithrombotic effects than sarpogrelate in a rat photochemically-induced thrombosis model.

Enhancement of O2- production from resident peritoneal macrophages by low-dose in vivo gamma-irradiation

Superoxide anion (O2-) production after very low-dose in vivo irradiation (4 cGy) was examined in resident peritoneal macrophages. The level of production rapidly increased following treatment with the PKC activator, phorbol 12-myristate 13-acetate (PMA), but no further enhancement by low-dose in vivo irradiation was observed. On the other hand, treatment with zymosan A gradually induced O2- production, which was further increased in low-dose in vivo irradiated macrophages. The amounts of phagocytosis of zymosan A were not changed by in vivo irradiation. This indicated that the enhancement of O2- production was not due to an increase in phagocytotic activity by low-dose in vivo irradiation. Our results show that low-dose in vivo irradiation induces production of reactive oxygen species by macrophages, not only nitric oxide as reported in our previous paper but also O2-. This may contribute to the increase of cytolytic activity of macrophages after low-dose in vivo irradiation.

Functional mapping of human brain in olfactory processing: a PET study

This study describes the functional anatomy of olfactory and visual naming and matching in humans, using positron emission tomography (PET). One baseline control task without olfactory or visual stimulation, one control task with simple olfactory and visual stimulation without cognition, one set of olfactory and visual naming tasks, and one set of olfactory and visual matching tasks were administered to eight normal volunteers. In the olfactory naming task (ON), odors from familiar items, associated with some verbal label, were to be named. Hence, it required long-term olfactory memory retrieval for stimulus recognition. The olfactory matching task (OM) involved differentiating a recently encoded unfamiliar odor from a sequentially presented group of unfamiliar odors. This required short-term olfactory memory retrieval for stimulus differentiation. The simple olfactory and visual stimulation resulted in activation of the left orbitofrontal region, the right piriform cortex, and the bilateral occipital cortex. During olfactory naming, activation was detected in the left cuneus, the right anterior cingulate gyrus, the left insula, and the cerebellum bilaterally. It appears that the effort to identify the origin of an odor involved semantic analysis and some degree of mental imagery. During olfactory matching, activation was observed in the left cuneus and the cerebellum bilaterally. This identified the brain areas activated during differentiation of one unlabeled odor from the others. In cross-task analysis, the region found to be specific for olfactory naming was the left cuneus. Our results show definite recruitment of the visual cortex in ON and OM tasks, most likely related to imagery component of these tasks. The cerebellar role in cognitive tasks has been recognized, but this is the first PET study that suggests that the human cerebellum may have a role in cognitive olfactory processing as well.

A PET study of visuomotor learning under optical rotation

We measured the regional cerebral blood flow (rCBF) in six healthy volunteers with PET (positron emission tomography) and H(15)(2)O to identify the areas of the human brain involved in sensorimotor learning. The learning task was visually guided reaching with sensorimotor discrepancy caused by optical rotation. PET measurements were performed in the early and late stages of the adaptation to the sensorimotor perturbation. Control measurements were obtained during an eye movement task and a reaching task without optical rotation. The rCBF data of each learning stage were compared to those of both control conditions. During the early stage, rCBF increases were detected in the rostral premotor cortex bilaterally, the posterior part of the left superior parietal lobule (SPL), and the right SPL including the intraparietal sulcus (IPS). During the late stage, rCBF increases were detected in the left caudal premotor area, the left supplementary motor area proper, the left SPL, the right SPL including the IPS, and the right postcentral sulcus extending to the inferior parietal lobule. These results reveal that sensorimotor learning accompanies changes in the recruited cortical areas during different stages of the adaptation, reflecting the different functional roles of each area for different components of adaptation, from learning of new sensorimotor coordination to retention or retrieval of acquired coordination.

Correlation between human personality and neural activity in cerebral cortex

Personality traits are a variance of behavioral patterns among individuals and may reflect a variance of brain activity, but their neurobiological explanation is still a matter of debate. Cloninger proposed three dimensions of personality traits, each of which has strong correlation with activity in a specific central monoaminergic system. Although this theory has been supported by physiological and genetic studies, it is still unclear how these personality parameters are correlated with the activity of the cortical networks which control human behavior. Here we measured the regional cerebral blood flow (rCBF) at rest in 30 normal volunteers who completed the personality inventory of Cloninger. Voxel-by-voxel analysis was employed to identify cortical regions where the rCBF showed significant correlation with any of the three personality parameters. Statistically significant correlation was observed in several paralimbic and neocortical regions and was consistent with the assumed monoaminergic influence on neural activity and the distribution of its projections, in each personality dimension. The results suggest that activity in a variety of cortical regions is associated with human personality traits and lend support to Cloninger's theory concerning central monoaminergic influence on human personality traits.

[2-(omega-phenylalkyl)phenoxy]alkylamines.II: Synthesis and selective serotonin-2 receptor binding

A series of [2-(omega-phenylalkyl)phenoxy]alkylamines was synthesized and their receptor binding affinity was examined in vitro. These compounds showed an affinity for serotonin-2 (5-HT2) and dopamine-2 (D2) receptors. [2-(2-phenylethyl)phenoxy]alkylamine derivatives with a pyrrolidine or piperidine moiety in the structure showed higher affinity for 5-HT2 receptors but lower affinity for D2 receptors. Among these compounds, (S)-2-[2- [2-[2-(3-methoxyphenyl)ethyl]phenoxy]ethyl]-1-methylpyrrolidine, (S)-27, exhibited the most potent and selective affinity for 5-HT2 receptors. Furthermore, (S)-27 was effective in inhibiting 5-HT-induced vasoconstriction in vitro and platelet aggregation both in vitro and ex vivo.

[Left atrial pressure gradient and right heart failure secondary to compression of the left atrium by a huge ascending aortic aneurysm: a case report]

A 71-year-old man was admitted to our department with congestive heart failure on June 28, 1998. He previously had an aortic valve replacement because of aortic regurgitation probably due to annuloaortic ectasia in 1984. Thoracic aortic aneurysm was identified during the postoperative course. Magnetic resonance imaging showed a huge saccular ascending aortic aneurysm of 12 x 11.5 x 9.5 cm size, which had severely compressed the left atrium. Doppler echocardiography documented an accelerated flow (2.2 m/sec) in the left atrium in early diastole. The calculated pressure gradient was 19 mmHg. All pressures in the right heart system were elevated. This is the first case of pulmonary hypertension and right heart failure secondary to compression of the left atrium in a patient with thoracic aortic aneurysm.

Prognostic significance of tumor grade for renal cell carcinoma

BACKGROUND

The natural history and prognosis of renal cell carcinoma cannot be predicted. Based on the Japanese classification system, the value of nuclear grade were assessed as a possible prognostic factor for renal cell carcinomas.

METHODS

In this retrospective study of 116 patients with renal cell carcinoma, radical nephrectomy was performed. Survival rates were calculated using the Kaplan-Meier method and multivariate analysis was performed using Cox's proportional hazard model.

RESULTS

Distribution by stage and grade in the population of renal cell carcinomas was as follows: pT1 in 13 cases (11.3%), pT2 in 65 cases (56.5%), pT3 in 36 cases (31.3%) and pT4 in one case (0.9%) and grade 1, 28 (24.1%), grade 2, 69 (59.5%) and grade 3, 16 (13.8%). Three cases could not be determined because of pre-operative embolization of the renal cell carcinomas. Nuclear grade was correlated with stage (P=0.0002), the presence of perirenal fat involvement (P=0.003) and metastases (P=0.007). A significant difference in survival was found between grades 1 and 3 (P=0.0001) and grades 2 and 3 (P=0.0001), respectively. Survival was significantly correlated with sex (P=0.0125), tumor size (P=0.0001), the presence of lymph node metastasis (P=0.0001), renal vein involvement (P=0.0001), perirenal fat involvement (P=0.002) or distant metastasis (P=0.0001). The multivariate analysis showed that the occurrence of tumor grade (P=0.0006) or distant metastasis were independent prognostic values.

CONCLUSION

The observations lead us to conclude that the nuclear grade according to the Japanese classification system appears to be of reliable prognostic value for renal cell carcinomas.

Contribution of inflammatory cytokine release to activation of resident peritoneal macrophages after in vivo low-dose gamma-irradiation

The activation mechanism of resident peritoneal macrophages by in vivo gamma-irradiation was investigated. The function of macrophages as accessory cells in concanavalin A-induced proliferation of spleno-lymphocytes (accessory function) was enhanced 4 h after a low-dose irradiation (4 cGy) in vivo, but not in vitro, indicating that low-dose irradiation acts indirectly on the activation of macrophages. Because we expected that macrophages were activated by the recognition of substances damaged by in vivo irradiation, we co-cultured macrophages with oxidized erythrocyte-ghosts. No change was found in their accessory function. The production of inflammatory cytokines, interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma), in the supernatant of cocultures of spleno-lymphocytes and macrophages was determined by an ELISA. Production of both increased in the presence of in vivo irradiated macrophages. Furthermore, IL-1 beta production from in vivo-irradiated macrophages treated with recombinant IFN-gamma also was enhanced. The mRNA expression of the cytokines released from macrophages and lymphocytes was determined by RT-PCR. Increases in IL-1 beta mRNA expression were found in both in vivo- and in vitro-irradiated macrophages. In vivo irradiation also enhanced the expression of IFN-gamma mRNA in lymphocytes, whereas there was no change after in vitro irradiation. On the basis of these observations, we propose that the activation of macrophages is caused by interaction with neighboring cells, such as lymphocytes, and by paracrine induction of certain cytokines which is initiated by the small amount of IL-1 beta released by irradiated macrophages.

Selective visual and auditory attention toward utterances-a PET study

The purpose of this study was to reveal functional areas of the brain modulating processing of selective auditory or visual attention toward utterances. Regional cerebral blood flow was measured in six normal volunteers using positron emission tomography during two selective attention tasks and a control condition. The auditory task activated the auditory, inferior parietal, prefrontal, and anterior cingulate cortices. The visual task activated the visual association, inferior parietal, and prefrontal cortices. Both conditions activated the same area in the superior temporal sulcus. During the visual task, deactivation was observed in the auditory cortex. These results indicate that there exists a modality-dependent selective attention mechanism which activates or deactivates cortical areas in different ways.

A comparison of Tc-99m HMPAO brain SPECT images of young and aged normal individuals

The purpose of this study was to examine the normal distribution patterns of 99mTc-HMPAO (HMPAO) in young and aged normal individuals and to clarify differences between the distribution patterns of the two groups by means of an anatomical standardization technique. The tracer distribution was measured with HMPAO and SPECT in 18 normal subjects; age range 20-81 yrs. SPECT images were globally normalized by averaging whole brain radioactivity counts to 100 counts/voxel. The SPECT images for each subject were transformed into the standard brain anatomy by means of a computerized brain atlas, together with each subject's CT images. Mean and SD images for young (28.8 +/- 6.4 yrs) and aged groups (62.3 +/- 10.2 yrs) were then calculated on a voxel-by-voxel basis. Statistically significant differences between young and aged groups were observed in the relative tracer distribution patterns. In the aged group, relative decreases were found in the cortical areas of the frontal and temporal lobes, limbic areas and basal ganglia regions. The results, as visualized changes in tracer distribution patterns with aging, may contribute to more accurate clinical diagnosis.

[A case of untreatable progressive bladder carcinoma effectively treated by single administration of tegafur and uracil]

Bloody urine was grossly observed and multinodular shadow confirmed in both lungs of an 81-year-old male, who had been referred to our department. The diagnosis was bladder cancer (TCC, G3, T4N3M1) from detailed examination. With his advanced age and lowered ADL, the family did not wish for aggressive treatment, so no combination multidrug chemotherapy was attempted. Instead he was given 300 mg/day UFT per os. After 4 weeks administration, the metastatic focus decreased and tended to contract; at the same time gross observation revealed no more bloody urine. Moreover, following 7 weeks of administration, the bladder tumor disappeared, the lung metastatic focus showed overall shrinkage of over 50%, the lymph node metastasis also was more than 50% less, and the case was considered to be PR. The literature reveals UFT was efficacious in only 2 other cases of progressive bladder carcinoma. Since UFT has fewer complications, such as myelosuppression, among antitumor agent, it is considered worth trying in cases where intensive treatment is not feasible.

Distribution of 14 elements in tissues and organs of oceanic seabirds

The concentrations of 14 trace elements (Li, V, Mn, Co, Cu, Zn, Se, Rb, Sr, Ag, Cd, Cs, Pb, and Hg) were determined in tissues and organs of three species and in the liver of 11 species of seabirds. Comparatively high concentrations of Li, Co, Sr, and V were found in the femur. Cd, Se, Cu, and Mn concentrations were relatively higher in the kidney than in other tissues and organs. Rb, Cs, and Pb concentrations were rather uniform among tissues. Concentrations of essential elements such as Mn, Cu, and Co were comparable among seabird species, except high Cu concentrations in northern giant petrel. Among nonessential elements, concentrations of Cd and Hg were variable according to seabird species. Pb levels were low in all the species. High Se levels (100 microg/g dry weight) were found in the liver of black-footed albatross and grey petrel. There were significant positive correlations between Se and Cd concentrations in three species and between Se and Hg in black-footed albatross, suggesting that Se has an antagonistic action on the toxic effects of Cd and Hg. Concentrations of Li, V, Ag, and Cs were usually low (less than 1 microg/g dry weight).

The role of the left inferior temporal cortex for visual pattern discrimination--a PET study

We measured regional cerebral blood flow using positron emission tomography in seven normal volunteers during discrimination tasks for visual patterns. For the 'attention to right or left' tasks, the subjects were instructed to press a key when sample and test stimuli presented in the right or left visual fields, respectively, were identical. In the control task, subjects were instructed to press a key on every second presentation of the test stimulus. Both discrimination tasks activated the same area in the inferior temporal sulcus of the left hemisphere. The results indicate that the left inferior temporal cortex plays a dominant role in the discrimination of visual pattern in right handed subjects.

Low-dose irradiation induces expression of heat shock protein 70 mRNA and thermo- and radio-resistance in myeloid leukemia cell line

We examined the effects of in vitro low-dose irradiation on myeloid leukemia cells (M1 cells) and found that it enhanced the colony-forming ability (CFA) of M1 cells in semi-solid agar. This enhancement was inhibited by treatment with a protein synthesis inhibitor, cycloheximide and with an RNA synthesis inhibitor, actinomycin D, after irradiation. These findings suggested that low-dose irradiation induced the synthesis of some proteins which were attributed to the enhancement of CFA. Since we expected that one species of these proteins were heat shock proteins (hsps), we attempted to detect the hsp70 family by the Western blotting method and inducible hsp70 mRNA by the RT-PCR method. Low-dose irradiation induced the expression of hsp70 mRNA, whereas the enhancement of hsp70 (an inducible isoform) and hsc70 (a constitutively expressed isoform) expression could not be found. Furthermore, the M1 cells showed thermoresistance 1 h after low-dose pre-irradiation, and also showed radioresistance 4 h after irradiation. This time difference after pre-irradiation might be attributed to the different species of proteins in showing resistance to lethal stress. Therefore, some proteins other than hsp70 were believed to be concerned with the augmentation of CFA and the induction of thermo- and radio-resistance.

[2-(omega-phenylalkyl)phenoxy]alkylamines: synthesis and dual dopamine2 (D2) and 5-hydroxytryptamine2 (5-HT2) receptor antagonistic activities

A series of [2-(omega-phenylalkyl)phenoxy]alkylamines was synthesized and their 5-hydroxytryptamine2 (5-HT2) and/or dopamine2 (D2) receptor antagonistic activities were examined in vitro. [2-(4-Phenylbutyl)phenoxy]alkylamines showed strong inhibition of both 5-HT2 and D2 receptors. In particular, [2-(4-Phenylbutyl)phenoxy]-methylpiperidine derivatives, 10b, 10i and 10q, exhibited potent inhibition. The structure-activity relationships in this series of compounds are discussed.

Mean regional cerebral blood flow images of normal subjects using technetium-99m-HMPAO by automated image registration

The purpose of this study was twofold: to calculate relative uptake values for 99mTc-HMPAO in various regions of the normal brain after alignment and registration to a standard shape and size, and to validate the automated image registration (AIR) program for SPECT-to-SPECT transformation.

METHODS

Thirty subjects took part in this study. Technetium-99m-HMPAO brain SPECT and x-ray-CT scans were acquired. SPECT images were normalized to an average activity of 100 counts/pixel. Intersubject accuracy was evaluated on brain images of 17 normal subjects (mean age = 64.9 +/- 8.7 yr). These images were aligned and registered to a standard size and shape with the help of AIR. Realigned images were overlaid on reference images to determine the overlap areas. Intrasubject accuracy was evaluated by realigning 20 degree rotated brain images with an index calculated as: overlap area/(overlap area + nonoverlap area). Anatomical variability between realigned target and reference images was evaluated by measurements on corresponding x-ray-CT scans, realigned using transformations that were established by the SPECT images. Realigned brain SPECT images of 30 normal subjects (mean age = 50.7 +/- 18.7 yr), including those subjects examined in the accuracy validation study, were used to generate mean and s.d. images. Images based on the mean value of each voxel (n = 30) were compared with other mean images prepared by the human brain atlas (HBA) standardization technique on a voxel-by-voxel basis to generate T maps.

RESULTS

Accuracy indices were 0.98 +/- 0.006 and 0.99 +/- 0.002 for the intersubject and intrasubject evaluations, respectively. The maximum anatomical variability was 4.7 mm after realignment. Paired Student's t-test comparisons of mean HBA and AIR images revealed statistically significant differences for the deep white matter, pons and occipito-temporal regions. These differences could be explained by variation in the population being studied and the protocol for data handling by AIR and HBA.

CONCLUSION

AIR aligns and registers brain SPECT images with acceptable accuracy, without the necessity of MRI or x-ray-CT scans.

PET study of pointing with visual feedback of moving hands

This study was conducted to determine where in the human brain visual feedback of hand movements is processed to allow accurate pointing. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) and H2 15O in nine normal volunteers while performing one control and two reaching tasks. In all tasks, visual stimuli were presented on a head mounted display (HMD). A target board was placed in front of the subjects bearing six red light-emitting diodes (LEDs) aligned on a circle with a green LED at its center. The center green LED and one of the six red LEDs, randomly selected, were repeatedly switched on and off, alternatively. In the control task, subjects were instructed to gaze at the lit LED. In the two reaching tasks, the reaching with visual feedback (RwithF) task and the reaching without visual feedback (RwithoutF) task, they had to point to the lit red LED with their right index fingers. In the RwithF task, their right hands were visible on the HMD before touching the target, whereas in the RwithoutF task, they were not visible. For each subject, subtraction images of each reaching task minus the control and the RwithF task minus the RwithoutF task were calculated after transformation of PET images into the standard brain shape with an adjustable computerized brain atlas. These subtraction rCBF images were then averaged among the subjects, and significant changes of rCBF were identified. Significant increases in rCBF not only in the RwithF task minus control image but also in the RwithF task minus the RwithoutF task image were observed in the supramarginal cortex, the premotor cortex and the posterior cingulate cortex of the left hemisphere, the caudate nucleus and the thalamus of the right hemisphere, and the right cerebellum and vermis. These results indicate that the supramarginal cortex, the premotor cortex, and the posterior cingulate cortex of the left hemisphere and the cerebellum are involved in integrating visual feedback of hand movements and execution of accurate pointing.

Activity in the parietal area during visuomotor learning with optical rotation

Regional cerebral blood flow (rCBF) was measured in six subjects to study changes of activity in the parietal cortex during learning of a visually guided pointing task with a discrepancy of visuomotor coordination and to determine whether reorganization affects the parietal activity after learning. During the early stage of learning, the right posterior parietal cortex showed a significant increase in rCBF. During the late stage, on the other hand, significant activation was noted in the postcentral gyrus of the right hemisphere. These results support a role for the posterior parietal cortex in remapping visuomotor coordinates and suggest the involvement of the human postcentral gyrus in retaining sensorimotor coordinates, considered to relate to the self image of the hand.

Interaction between oral alpha-streptococci and group A streptococci in patients with tonsillitis

The incidence of oral alpha-streptococci with inhibitory activity against group A streptococci, as a defense mechanism against bacterial infection in the oral cavity, was investigated in 141 patients with streptococcal tonsillitis. The study population included both children (n = 79) and adults (n = 62). Infection by group A streptococci appeared to be more common in children than in adults, as the detection rates of inhibitory alpha-streptococci in healthy children (29.7%), as well as pediatric patients with tonsillitis (14.9%), were lower than those in adults (63.0%; p < .01). It is possible to consider oral alpha-streptococci with inhibitory activity to be among the indications for tonsillectomy in patients with streptococcal tonsillitis, since the detection rate of inhibitory alpha-streptococci in surgical cases (10.9%) was significantly lower than that in nonsurgical cases (31.1%; p < .01). The high detection rate of these strains during the postoperative state supported the observation that the incidence of group A streptococcal infection was decreased postoperatively. Accordingly, it is useful to investigate bacterial interference between oral alpha-streptococci and group A streptococci in patients scheduled for tonsillectomy.

Cranial computed tomography scans of premature babies predict their eventual learning disabilities

It remains difficult to predict, early enough to intervene effectively, the risk of the development of learning disabilities among extremely low birth weight (ELBW) infants (birth weights less than 1,000 g). We prospectively studied the relationship between dilatations of lateral ventricles of the cranial computed tomography (CT) scan taken at the postconceptional age of 40 weeks and learning disabilities in their school age. Using a computer digitizer, we measured the areas of ventricles on cranial CT scans. The mean area of lateral ventricles of the learning disabilities-suspected group was significantly larger than that of the control group (392.9 and 277.4 mm2, respectively; P < .01). There were no significant differences between the two groups in gestation, birth weight, physical measurements, and developmental quotients at early school age. The dilatation of the lateral ventricles assessed by cranial CT at the corrected term may be one of the first predictors of learning disabilities recognizable at early school age.

A method for the quantification of benzodiazepine receptors by using 123I-iomazenil and SPECT with one scan and one blood sampling

Iodine-123-iomazenil (Iomazenil) is a ligand of central type benzodiazepine receptors for single photon emission computed tomography (SPECT). Previously we reported a simple, table look-up method for quantification of its binding potential (BP) by using two SPECT scans and calibrated standard input function with one blood sampling. This method is based on a two-compartment model (K1: influx rate constant; k2: efflux rate constant; Vd (= K1/k2): the total distribution volume corresponding BP), and requires two SPECT scans for calculating both K1 and Vd values. If the K1 value in the two-compartment model can be assumed to be constant, the radioactivity of one SPECT scan at 180 min after injection can be considered to tabulate as a function of Vd for a given K1 value and a given input function, and a table look-up procedure provides the corresponding Vd value. The purpose of this study was to develop a simple, autoradiographic method for quantification of BP by using one SPECT scan and calibrated standard input function with one blood sampling. SPECT studies were performed on 14 patients. A dynamic SPECT scan was initiated following an intravenous bolus injection of Iomazenil. A static SPECT scan was performed at 180 min after the injection. Frequent blood sampling from the brachial artery was performed on all subjects to determine the arterial input function. Simulation studies revealed that errors in calculated Vd values were around +/-10-15% for varied K1 values. A good correlation was observed between total distribution volume values calculated by three-compartment model analysis and those calculated by the present method (r = 0.90), supporting the validity of this method. The present method is simple and applicable for clinical use, and will be able to provide images of BP.