Expression of hsp70 mRNA is induced in the brain of transgenic mice overexpressing human CuZn-superoxide dismutase following transient global cerebral ischemia

We examined hsp70 mRNA expression in the brains of transgenic (Tg) mice overexpressing CuZn-superoxide dismutase and in wild-type (Wt) littermates after 3 min of bilateral common carotid artery occlusion. Significant induction of hsp70 mRNA occurred in the hippocampus, the cortex, and other brain regions of the Tg mice 4 h after ischemia compared to the Wt mice. However, there was no histological damage in the brains of Tg and Wt mice as assessed by both Cresyl violet staining and by TUNEL staining for DNA fragmentation. These data suggest that high levels of CuZn-superoxide dismutase activity increase hsp70 mRNA expression and that intense hsp70 mRNA expression does not predict neuronal damage, even in vulnerable hippocampal CA1 neurons.

Effects of feeding tryptophan-limiting diets on the conversion ratio of tryptophan to niacin in rats

We investigated the effects of feeding various types of nicotinic acid-free, tryptophan-limiting diets on the conversion ratio of tryptophan to niacin in rats. Various tryptophan-limiting diets were made by adding zein, gelatin, glycine, threonine, methionine, or glycine + threonine + methionine to a nicotinic acid-free, 9% casein diet. When the rats were fed with the tryptophan-limiting diets, the conversion ratio of tryptophan to niacin was markedly decreased. However, the ratio recovered after the addition of tryptophan to the tryptophan-limiting diets. These results clearly prove that the conversion was lowest when the rats were fed with the tryptophan-limiting diets. Therefore, we think that the pellagragenic factor of corn is simply due to a low content of tryptophan, but the adverse effect is due to a low conversion ratio of tryptophan to niacin.

Possible inhibitory effect of diazepam on the metabolism of zotepine, an antipsychotic drug

Effects of smoking and cytochrome P450 2C19 (CYP2C19) status on the single dose kinetics of zotepine and pharmacokinetic interaction between zotepine and diazepam were investigated. In 14 healthy volunteers, the pharmacokinetics of zotepine after a single oral 25 mg dose were compared between eight smokers and six non-smokers, or between seven extensive metabolizers (EMs) and seven poor metabolizers (PMs) of S-mephenytoin. There was no significant difference in any pharmacokinetic parameters between smokers and non-smokers, or between the EM and PM groups. In 17 patients treated with zotepine 80-340 mg/day, intra-individual changes in plasma concentrations of zotepine caused by coadministration of diazepam 10 mg/day for 2 weeks were examined. Plasma concentrations of zotepine were significantly increased after coadministration of diazepam (P < 0.05). Consequently, it is suggested that neither smoking nor CYP2C19 status affects the metabolism of zotepine. The elevation in plasma concentrations of zotepine after coadministration of diazepam may be a result of competitive inhibition of zotepine metabolism by diazepam via other isoenzyme than CYP2C19, e.g., CYP3A4.

Zebrafish Hoxa and Evx-2 genes: cloning, developmental expression and implications for the functional evolution of posterior Hox genes

Vertebrate Hox genes are required for the establishment of regional identities along body axes. This gene family is strongly conserved among vertebrates, even in bony fish which display less complex ranges of axial morphologies. We have analysed the structural organization and expression of Abd-B related zebrafish HoxA cluster genes (Hoxa-9, Hoxa-10, Hoxa-11 and Hoxa-13) as well as of Evx-2, a gene closely linked to the HoxD complex. We show that the genomic organization of Hoxa genes in fish resembles that of tetrapods albeit intergenic distances are shorter. During development of the fish trunk, Hoxa genes are coordinately expressed, whereas in pectoral fins, they display transcript domains similar to those observed in developing tetrapod limbs. Likewise, the Evx-2 gene seems to respond to both Hox- and Evx-types of regulation. During fin development, this latter gene is expressed as the neighbouring Hox genes, in contrast to its expression in the central nervous system which does not comply with colinearity and extends up to anterior parts of the brain. These results are discussed in the context of the functional evolution of Hoxa versus Hoxd genes and their different roles in building up paired appendages.

Development of low potassium solution (EP4 solution) for long-term preservation of a lung transplant: evaluation in primate and murine lung transplant model

The results of recent studies on long-term preservation using low potassium flush solution, which was originally produced in our department, are presented and discussed. In the primate model, a lung preserved for 24 h with EP4 solution retained sufficient function in single lung allotransplantation. In the murine experiments, we have evaluated the ion transport properties across alveolar epithelial cells in the transplanted lung using the tools of alveolar fluid clearance tests. The alveolar fluid clearance rate, which can be inhibited by 10(-3) M ouabain, is also well preserved for the first 24 h, indicating that the alveolar epithelial Na-K-ATPase is still functioning and that the 72 h preservation decreases those function of Na-K-ATPase in a time-dependent manner. In conclusion, because 24 h hypothermic preservation with EP4 solution did not show any obvious disadvantage on primate lung allografts and the cellular and molecular viability of the preserved lung flushed with EP4 solution could be retained for 24 h, this kind of solution with extracellular electrolyte composition can be applicable in the clinical settings.

Amyloid beta 2-microglobulin is modified with N epsilon-(carboxymethyl)lysine in dialysis-related amyloidosis

Recent work from this laboratory revealed that advanced glycation end product was localized to amyloid deposits in patients with dialysis-related amyloidosis by immunohistochemistry using a monoclonal antibody to advanced glycation end product. To elucidate the epitope of the antibody, N alpha-p-tosyl-L-lysine-methyl ester was incubated with glucose in vitro, and then a compound reactive to the antibody was purified from the incubate by buthanol extraction, XAD-2 column chromatography, and high-performance liquid chromatography while the reactivity was examined by enzyme linked immunosorbent assay. The purified compound was identified as N epsilon-(carboxymethyl)-N alpha-p-tosyl-L-lysine-methyl ester by using secondary ion mass spectrometry, and 1H- and 13C-nuclear magnetic resonance spectroscopy. The epitope of the antibody was identified as -CH2-NH-CH2-COOH by enzyme-linked immunosorbent assay of compounds with structures similar to N epsilon-(carboxymethyl)lysine. Immunochemical study using the antibody demonstrated the presence of N epsilon-(carboxymethyl)lysine in the beta 2-microglobulin dimer (molecular weight 23929) isolated from the synovium amyloid of a hemodialysis patient with dialysis-related amyloidosis. In conclusion, amyloid beta 2-microglobulin is modified with N epsilon-(carboxymethyl)lysine in dialysis-related amyloidosis.

Genotyping of ABO blood group system by PCR and RFLP on mummies discovered at Taklamakan desert in 1912

ABO genotyping was carried out using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) method on the dried remains of nine human mummies which had been discovered at Taklamakan desert in 1912. In all the nine mummies, ABO genotype could be determined as BO type, and ABO phenotype of the eight mummies with hair specimen could be revealed as B type using absorption-elution method. These results mean that ABO phenotype estimated from its genotype by PCR-RFLP was consistent with that by absorption-elution method in all of the eight cases examined. And in the other one child mummy, ABO phenotype could not be examined because of no hair specimen. Although it is impossible to assess the allele frequency of ABO blood group system in the populations having lived in Gao Chang at that time, the present study shows a possibility of ABO genotyping from ancient human remains.

Impairment of antioxidants in colonic epithelial cells isolated from trinitrobenzene sulphonic acid-induced colitis rats. Protective effect of rebamipide

BACKGROUND

The functional status of glutathione, its related enzymes, and Cu,Zn-superoxide dismutase in colonocytes isolated from rats with trinitrobenzene sulphonic acid-induced colitis, and the effect of rebamipide (a scavenger) on these antioxidants and on colitis, were studied.

METHODS

The rats were treated with rebamipide, killed on day 14, and compared with controls. Glutathione and enzymatic activities were spectrophotometrically estimated. The effect of rebamipide on colitis was also assessed histologically and by myeloperoxidase activity.

RESULTS

In controls the concentration of glutathione and the activities of glutathione S-transferase and Cu,Zn-superoxide dismutase were decreased, but that of glutathione peroxidase was increased. Rebamipide prevented the impairment of these enzymes, restored the concentration of glutathione, and attenuated (low damage scores and myeloperoxidase activity) the severity of the colitis.

CONCLUSIONS

These features suggest that the impairment of antioxidants is closely related to the development of the inflammatory lesions, and rebamipide has a beneficial effect on experimental colitis.

[Assessment of prognostic factors in surgical treatment for the pulmonary metastasis of osteosarcoma based on results of 17 patients]

Seventeen cases with surgical treatment for pulmonary metastases of osteosarcomas have been experienced for past 20 years in our institute. Disease free intervals, tumor doubling time, the number of metastatic lesions, the size of metastatic lesions, pathological features on nuclear findings were assessed in relation to their prognosis. These parameters were concluded to have no significant relations to the survival outcomes after the surgery for pulmonary lesions except for the number of metastatic lesions less than 20 in total which is likely to be associated with long survivals, supporting previous reports on the resectability of pulmonary metastatic lesions as an only reliable prognostic indicator. It was also stressed from our experience that the meticulous follow-up after each surgery for both primary and metastatic lesions is absolutely necessary for the early detection of recurrent pulmonary lesions in order not to overlook curable cases with aggressive treatment.

Regulation mechanism of ERM (ezrin/radixin/moesin) protein/plasma membrane association: possible involvement of phosphatidylinositol turnover and Rho-dependent signaling pathway

The ERM proteins, ezrin, radixin, and moesin, are involved in the actin filament/plasma membrane interaction as cross-linkers. CD44 has been identified as one of the major membrane binding partners for ERM proteins. To examine the CD44/ERM protein interaction in vitro, we produced mouse ezrin, radixin, moesin, and the glutathione-S-transferase (GST)/CD44 cytoplasmic domain fusion protein (GST-CD44cyt) by means of recombinant baculovirus infection, and constructed an in vitro assay for the binding between ERM proteins and the cytoplasmic domain of CD44. In this system, ERM proteins bound to GST-CD44cyt with high affinity (Kd of moesin was 9.3 +/- 1.6nM) at a low ionic strength, but with low affinity at a physiological ionic strength. However, in the presence of phosphoinositides (phosphatidylinositol [PI], phosphatidylinositol 4-monophosphate [4-PIP], and phosphatidylinositol 4.5-bisphosphate [4,5-PIP2]), ERM proteins bound with a relatively high affinity to GST-CD44cyt even at a physiological ionic strength: 4,5-PIP2 showed a marked effect (Kd of moesin in the presence of 4,5-PIP2 was 9.3 +/- 4.8 nM). Next, to examine the regulation mechanism of CD44/ERM interaction in vivo, we reexamined the immunoprecipitated CD44/ERM complex from BHK cells and found that it contains Rho-GDP dissociation inhibitor (GDI), a regulator of Rho GTPase. We then evaluated the involvement of Rho in the regulation of the CD44/ERM complex formation. When recombinant ERM proteins were added and incubated with lysates of cultured BHK cells followed by centrifugation, a portion of the recombinant ERM proteins was recovered in the insoluble fraction. This binding was enhanced by GTP gamma S and markedly suppressed by C3 toxin, a specific inhibitor of Rho, indicating that the GTP form of Rho in the lysate is required for this binding. A mAb specific for the cytoplasmic domain of CD44 also markedly suppressed this binding, identifying most of the binding partners for exogenous ERM proteins in the insoluble fraction as CD44. Consistent with this binding analysis, in living BHK cells treated with C3 toxin, most insoluble ERM proteins moved to soluble compartments in the cytoplasm, leaving CD44 free from ERM. These findings indicate that Rho regulates the CD44/ERM complex formation in vivo and that the phosphatidylinositol turnover may be involved in this regulation mechanism.

No interaction between desipramine and bromperidol

1. The authors studied the effects of coadministration of desipramine, which is a substrate of CYP2D6, on plasma concentrations of bromperidol and its reduced metabolite (reduced bromperidol). Clinical changes were also evaluated by the CGI and UKU. 2. The subjects were 13 schizophrenic inpatients receiving bromperidol 12.24 mg/day for 1.20 weeks. Desipramine 50 mg/day was coadministered for 1 week, and blood samplings and clinical ratings were performed before and after the coadministration. 3. Plasma concentrations of bromperidol and reduced bromperidol were measured by a HPLC method. 4. Desipramine coadministration did not affect plasma concentration of bromperidol (9.6 +/- 4.5 vs. 9.6 +/- 2.8 ng/ml) nor that of reduced bromperidol (2.8 +/- 2.5 vs. 2.8 +/- 2.1 ng/ml). 5. There was no significant change in the CGI scores nor UKU scores after desipramine coadministration. 6. The present study thus suggests that there is no interaction between desipramine and bromperidol.

Two-dimensional electrophoretic studies on down-regulated intracellular transferrin in human fibroblasts immortalized by treatment with either 4-nitroquinoline 1-oxide or 60Co gamma rays

The immortalization of human cells is an important early step of carcinogenesis. To investigate the mechanisms of immortalization, we established three immortalized human fibroblast cell lines by treatment with either 4-nitroquinoline 1-oxide (4NQO) or 60Co gama rays. Using two-dimensional gel electrophoresis (2-D PAGE), we identified proteins which are down-regulated in these immortalization cell lines. Their isoelectric points ranged between 5.5 and 6.3, and their molecular masses were approximately 80 kDa. The proteins were also decreased in another human fibroblast cell line immortalized with simian virus 40 (SV40) and two human cervical cell lines. The proteins were present in a cytoskeletal fraction, reacted with anti-transferrin antibody and some of them were phosphorylated. The proteins were identified as transferrin. Although the 2-D PAGE patterns of our proteins and serum transferrin of different origin were distinct from each other, their isoelectric points and molecular weights were similar. We implicate some functions of intracellular transferrin, other than an iron transporter, in immortalization of human cells and discuss a new aspect of transferrin metabolism in the cells.

Breath hydrogen and methane excretion produced by commercial beverages containing dietary fiber

Soft drinks containing dietary fiber are popular in Japan. There seem to be two types, one containing polydextrose and the other, oligosaccharide. These beverages are claimed to be useful for constipation or obesity, but data are scanty. We examined four such fiber-containing beverages [Fibe-mini Otsuka Pharmaceuticals (Tokyo, Japan), Seni and Oligo Takeda Food Engineering (Osaka, Japan), Oligo CC (Calpis Food Engineering, Tokyo, Japan), and Sapitus 5289 Nakakita Pharmaceuticals (Nagoga, Japan)] for large intestine fermentability by measuring breath hydrogen (H2) and methane (CH4). Five healthy subjects (two men, three women, 22-48 years old) participated in the study. Breath H2 and CH4 were measured with a MicroLyzer (Quintron Instruments, Milwaukee, Wis.). Breath H2 increased within 2h of beverage consumption, but CH4 excretion was observed in only two subjects. Orocecal transit time was constant for all beverages. Total H2 plus CH4 excretion (AUC; area under the curve) after lactulose was 1294 +/- 250 ppm x min/g fiber. AUC for Oligo CC was significantly greater than that for Fibe-mini or Sapitus 5289 (P < 0.05). The AUCs of Fibe-mini, Seni and Oligo, Oligo CC, and Sapitus 5289 were 41%, 129%, 174%, and 40%, respectively, that of lactulose. It is concluded that commercial fiber-containing drinks produce H2, and CH4 in some people. Oligosaccharide produces more H2 and CH4 than polydextrose.

Abnormal gel-electrophoretic behavior of presenilin 1 and it's fragment

Presenilin 1 (PS-1) is the main causal gene of familial Alzheimer's disease. In this report, we describe the abnormal behavior of PS-1 in gel electrophoresis in the presence of SDS. Freshly in vitro synthesized PS-1 was identified as a single molecule with the molecular size of 43,000 on SDS gels but was found to disappear after incubation at 37 degrees C for 24 hr due to the formation of aggregates. Intermediate aggregates with M(r) 74,000 and 100,000 were formed before the final aggregate which was retained at the top of the gel. Thus the amount of 43,000-protein species of PS-1 was found to decrease on gels with a concomitant increase in the amount of 74,000/100,000 proteins. Similar abnormality was seen in PS-1 expressed in COS cells transfected with PS-1 cDNA. Moreover, cellular PS-1 was strongly suggested to be cleaved into the fragments with M(r) approximately 20,000 in COS and CHO cells. Fragmentation of cellular PS-1 was not affected by the missense point mutation of Ala260Val on PS-1 which was identified in a pedigree with familial Alzheimer's disease.

Response of tracheal smooth muscle tone to lower brain stem hypoxia in dogs

We examined effects of central hypoxia on tracheal smooth muscle (TSM) tone, phrenic nerve activity (PNA) and blood pressure (BP) in decerebrated, paralysed, and artificially ventilated dogs. Central hypoxia was induced by injection of N2-saturated saline (5 ml; PO, 25-32 torr) through a catheter in the vertebral artery. The effects of central hypoxia were compared with the responses to central chemoreceptors stimulation, namely central hypercapnia induced by intravertebral injection of high CO2 saline (5 ml; PCO2 90-100 torr, PO2 80-120 torr, pH 7.38-7.42) buffered by HCO3-. Central hypoxia caused relaxation of TSM accompanied by depression of PNA and elevation of BP. In contrast, central hypercapnia evoked tracheal constriction along with respiratory excitation and pressor response. The tracheal relaxation in response to central hypoxia occurred with onset and peak latencies similar to those observed in PNA depression and BP elevation. This suggests a common source for the synaptic inputs to three distinct control systems involved in cardiovascular, respiratory and airway functions. Such neuronal substrate is considered to be activated by central hypoxia.

bcl-2 protein is increased in the brain from parkinsonian patients

The proto-oncogene bcl-2 is involved in the regulation of cell death and may be able to block apoptosis in neurons through reduced generation of reactive oxygen species (ROS). The bcl-2 product was measured for the first time in brain (caudate nucleus, putamen and cerebral cortex), ventricular cerebrospinal fluid (VCSF), and lumber CSF (LCSF) from control and parkinsonian patients by highly sensitive two-site sandwich enzyme-linked immunosorbent assay (ELISA). The concentrations of bcl-2 in the nigrostriatal dopaminergic regions were significantly higher in parkinsonian patients than those in controls, whereas this product in cerebral cortex showed no significant difference between parkinsonian and control subjects. Neither VCSF nor LCSF from control or parkinsonian subjects contained the bcl-2 product in the detectable amount (< 5 U/ml). Since oxidative stress may be involved in neurogenerative disorders, accumulation of bcl-2 may reflect a mechanism for counterbalancing ROS-mediated damage, or it might represent the impairment of bcl-2-dependent protection from ROS in parkinsonian brain.

Differential response in the release of hydrogen peroxide between astroglial cells and endothelial cells following hypoxia/reoxygenation

Hydrogen peroxide (H2O2) and lactate dehydrogenase (LDH) released from cultured astroglial cells (AGs) and brain endothelial cells (BECs) were measured following hypoxia/reoxygenation. AGs released H2O2 to the extracellular space from 8 h of hypoxia with the cellular injury indicated by LDH increase. In contrast, BECs released H2O2 at 4 h of hypoxia, prior to the LDH increase. These results suggest that AGs and BECs play different roles in production and metabolism of oxygen free radicals in the blood-brain barrier (BBB), and AGs may protect the BBB disruption from oxidative stress after hypoxia/reoxygenation.

Interferon-gamma inducible protein (IP-10) expression is mediated by CD8+ T cells and is regulated by CD4+ T cells during the elicitation of contact hypersensitivity

To investigate the potential roles of CD4+ and CD8+ T cells during contact hypersensitivity, we examined the T-cell-dependent expression of proinflammatory cytokine genes in the responses to dinitrofluorobenzene and oxazolone. Whole cell RNA was isolated from challenged ear tissue and analyzed for level of cytokine gene expression by Northern blot and densitometry analysis. Expression of interleukin 1 beta and the three chemokine genes (IP-10, JE, and KC) examined was dependent on the hapten dose used for sensitization and correlated with the immune response, i.e., ear swelling, elicited. Antibody-mediated depletion of CD8+ T cells before sensitization resulted in the absence of IP-10 expression following hapten challenge, indicating the ability of immune CD8+ T cells to mediate IP-10 expression. Depletion of CD4+ T cells resulted in higher levels of IP-10 and KC expression during elicitation of contact sensitivity, suggesting CD4+ T cells inhibit the expression of these proinflammatory genes. Depletion of CD4+ T cells resulted in contact hypersensitivity responses of higher magnitude and depletion of CD8+ T cells resulted in responses of lower magnitude. Transfer of CD8+ T-cell-depleted immune cells resulted in low, but detectable levels of IP-10 expression, indicating the ability of some oxazolone-immune CD4+ T cells to mediate IP-10 expression. These results indicate the differential induction of proinflammatory cytokine gene expression during elicitation of contact hypersensitivity in which expression of IP-10 is primarily mediated by immune CD8+ T cells and inhibited by immune CD4+ T cells.

The dynamics of inflammatory cytokines in the healing process of mouse skin wound: a preliminary study for possible wound age determination

The dynamics of inflammatory cytokines such as interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF alpha) during the healing process of mouse skin wounds were examined using the enzyme-linked immunosorbent assay and immunostaining. The applicability of this examination for wound age estimation is discussed from the perspective of forensic pathology. After wound induction, mice were sacrificed at intervals ranging from 0 to 240 h. The levels of TNF alpha and IL-1 beta began to elevate rapidly after wounding and reached a peak at 3 h. The IL-1 alpha level reached a peak at 6 h, and IL-6 peaked at 12 h. An infiltration of numerous leukocytes, indicating acute inflammation, was observed at 3 and 6 h, and the main source of the cytokines was immunohistochemically identified as neutrophils. These results indicate that TNF alpha and IL-1 beta play an important role in the commencement of inflammation. "Rebound" of cytokine levels, i.e. a re-increase, was observed at 72 h after wounding. Histological examination of the 72-h-old wound showed migration of fibroblasts and the formation of new granulation tissues, indicating the proliferative stage of the wound healing process. These experimental findings indicate that these cytokines have a close relationship to wound remodeling as well as to inflammation. From the viewpoint of forensic pathology, it is considered that inflammatory cytokines may become one of the markers for wound age estimation, but further studies are needed, especially those involving the investigation using human wound specimens with known time intervals after injury.

[Clinicopathologic assessment of primary thymic carcinoma based on eighteen cases]

In order to study clinicopathologic characteristics of thymic carcinomas, 18 patients with thymic carcinoma and 56 patients with invasive thymoma were reviewed. All of them were underwent thoracotomy. Both 5-year and 10-year survival rates were 44% in the thymic carcinoma patients, while 5-year survival and 10-year survival rates were respectively 62% and 52% in the invasive thymoma patients. The survival rate of the thymic carcinoma cases was significantly lower than that of invasive thymoma cases (p < 0.05). Both surgical technique and anticancer chemotherapy. However, have been improved in these years, such as artificial vessels for great veins, panpleuro-pneumonectomy, cisplatin and so on. Those new techniques have brought the significantly higher survival rate in recent 10 cases of thymic carcinoma patients. Three-year survival rate of 10 cases after 1990 was 80% and it was 13% in 8 cases before 1989 (p < 0.01). We conclude that surgical procedure are necessary for the treatment of thymic carcinoma patients, and both chemotherapy and radiotherapy should be combined with the surgical procedures to completely remove the tumors.

Absorption of the anxiolytic pazinaclone in animals as a criterion for species selection for toxicity studies

In rats, mice, hamsters, and guinea pigs given a 5 mg/kg oral dose of pazinaclone (CAS 103255-66-9), unchanged drug concentration in plasma was highest in mice (AUC; 90 ng.h/ml), followed in decreasing order by guinea pigs (AUC; 41 ng.h/ml), hamsters (AUC; 18 ng.h/ml), and rats (AUC; 17 ng.h/ml). In terms of plasma drug concentrations and toxicological background data, there was no better alternative rodents than mice and rats for the toxicity studies. Among rabbits, dogs, and monkeys, the dogs had the highest plasma drug concentrations: AUCs of pazinaclone in dogs and monkeys were 1035 and 458 ng. h/ml, respectively (drug concentration in rabbit plasma was very low). Of the two polymorphs, forms 1 and 2 with particle size of < or = 5 microns, the oral absorption of form 2 in rats was more efficient than that of form 1 at 1000 mg/kg: AUCs of pazinaclone after dosing of form 1 and 2 were 489 and 965 ng.h/ml, respectively. However, form 1 was selected for the toxicity studies because of the poor physico-chemical properties of forms 2. Form 3 was not included in this study, because this form was relatively unstable and contained relatively large amount of impurities. The absorption of pazinaclone in dogs was improved by decreasing its particle size: AUCs of pazinaclone after dosing of the drug having particle size of 5.5, 20.8, and 79.3 microns were 1361, 822, and 297 ng.h/ml, respectively. Since large-scale preparation of bulk pazinaclone with a particle size of 5 microns or smaller was not feasible, the drug having a particle size of about 20 microns was used in the toxicity studies. The absorption of pazinaclone was more extensive when the drug was given to fed animals as suspension. Thus, the toxicity studies were performed using form I of pazinaclone with a particle size of about 20 microns primarily in rats, mice, and dogs.