Lafutidine can improve the quality of gastric ulcer healing in humans: a randomized, controlled, multicenter trial

Improving the quality of ulcer healing (QOUH) is one of the valid methods of prevention of relapse of gastric ulcers. We investigated the effect of lafutidine on the QOUH of gastric ulcer compared with famotidine in a randomized, multi-centre controlled trial. Consecutive 80 patients with a gastric ulcer were randomly assigned to receive twice daily either lafutidine (10 mg) or famotidine (20 mg) for 12 weeks. Esophagogastroduodenoscopy was performed to examine the ulcer healing rate and rate of flat type ulcer scars using dye-contrast. The gastric ulcer healing rate was 92.1% in the lafutidine group (35/38) and 94.7% in the famotidine group (36/38). The rate of flat-type ulcer scars was significantly higher in the lafutidine group (68.4%, 26/38) than in the famotidine group (42.1%, 16/38) (P = 0.021). In conclusion, the present study demonstrated that lafutidine, as compared to famotidine, yields a significantly superior QOUH in patients with gastric ulcers in the clinical setting.

Solitary pulmonary granuloma caused by Mycobacterium avium-intracellulare complex

OBJECTIVES

To analyse the clinical features and high resolution computed tomography (HRCT) findings of solitary pulmonary granulomas caused by the Mycobacterium avium-intracellulare (MAI) complex.

METHODS

We retrospectively analysed a series of 73 consecutive patients with solitary pulmonary granuloma and negative sputum smear and culture results, in whom the diagnosis was established by histological examination of specimens obtained by partial pulmonary resection or lobectomy. We compared the clinical features and HRCT findings of the solitary pulmonary granulomas definitively diagnosed to be caused by the MAI complex with those of granulomas of other causes by univariate and multivariate analyses.

RESULTS

In this study series of 24 patients with solitary pulmonary granuloma, the aetiological agent was established as being the MAI complex. According to the results of the multivariate analysis, 'female sex', 'pleural indentation' and 'lobulation' on the HRCT images were significantly associated with solitary pulmonary granuloma caused by the MAI complex.

CONCLUSION

This study demonstrated several characteristics of solitary pulmonary granulomas caused by the MAI complex, and suggested that it might be a subtype of pulmonary MAI complex infection without the typical radiographic features of the infection.

Diagnostic accuracy of CT-guided percutaneous cutting needle biopsy for thymic tumours

AIM

To determine the diagnostic accuracy of computed tomography (CT)-guided percutaneous cutting needle biopsy (PCNB) for thymic tumours in accordance with the World Health Organization (WHO) classification.

MATERIAL AND METHODS

We retrospectively analysed a consecutive series of 138 cases in which CT-guided PCNB had been performed for an anterior mediastinal tumour. Its sensitivity and specificity for thymic epithelial tumours were evaluated, and the concordance between the histopathological diagnosis according to the WHO classification of thymic tumours based on PCNB and the diagnosis is based on the surgical specimens was assessed by Kappa statistic.

RESULTS

The diagnostic sensitivity and specificity of CT-guided PCNB for thymic tumours were 93.3 and 100%, respectively. The overall concordance between the diagnosis according to the WHO classification established by PCNB specimen and by the surgical specimen was 79.4% (weighted kappa=0.79).

CONCLUSION

CT-guided PCNB is a reliable method of diagnosing thymic tumours, and there was good concordance for the WHO classification between the diagnosis based on CT-guided PCNB specimen and that based on the surgical specimen.

Endovascular therapy followed by stereotactic radiosurgery for cerebral arteriovenous malformations

SUMMARY

Pre-radiosurgical embolization was carried out using cyanoacrylate in seven of 13 patients with cerebral arteriovenous malformations (AVMs) treated by stereotactic radiosurgery (SRS) with a linear accelerator (LINAC). The aim of embolization before SRS was the reduction of AVM volume and/or the elimination of vascular structures bearing an increased risk of haemorrhage. Staged-volume SRS was also performed in two patients because of residual irregular shaped nidus of AVMs even after the embolizations. Complete obliteration of the AVM nidus on angiogram was presented in five patients with embolizations (including one with staged-volume SRS) and in three of six patients with SRS alone, during follow-up periods after radiosurgery. No patients experienced haemorrhagic events after SRS. Although transient neurological symptoms were observed after embolizations in two patients, no permanent neurological deficits were presented in all patients with SRS. Pre-radiosurgical embolization may allow the effective influence on irradiation therapy in relatively large AVMs and promote more frequent obliteration in more small sized AVMs compared to those with SRS alone. However, further study must be needed to determine whether staged-volume SRS provides a high rate of AVM obliteration and its safeness.

Famotidine vs. omeprazole: a prospective randomized multicentre trial to determine efficacy in non-erosive gastro-oesophageal reflux disease

BACKGROUND

Several studies in Western countries showed that proton-pump inhibitors are superior to histamine2-receptor antagonists or placebo in the treatment of non-erosive gastro-oesophageal reflux disease. The efficacy of acid-suppressive drugs for non-erosive gastro-oesophageal reflux disease in Japan, in which the prevalence of Helicobacter pylori infection is higher compared with Western countries, is unknown.

AIM

To compare the efficacy of famotidine and omeprazole in Japanese patients with non-erosive gastro-oesophageal reflux disease by a prospective randomized multicentre trial.

METHODS

A total of 98 patients received either famotidine 20 mg b.d. (n = 48) or omeprazole once daily (n = 50). Frequency of gastro-oesophageal reflux disease symptoms and health-related quality of life were evaluated at baseline and after 4 weeks of treatment. Complete relief was defined as no gastro-oesophageal reflux disease symptoms during the 7-day interval in week 4.

RESULTS

Complete relief was achieved in 23 (48%) of patients receiving famotidine and 28 (56%) of patients treated with omeprazole. In the famotidine group, complete relief rate in H. pylori-negative patients was significantly lower than H. pylori-positive patients (35% vs. 64%). Both famotidine and omeprazole improved most scales of health-related quality of life. Omeprazole significantly improved reflux score irrespective of H. pylori infection while famotidine significantly improved reflux score in H. pylori-positive patients but not in H. pylori-negative patients.

CONCLUSIONS

Omeprazole is more effective than famotidine for the control of gastro-oesophageal reflux disease symptoms in H. pylori-negative patients, while similar efficacy is observed in H. pylori-positive patients with non-erosive gastro-oesophageal reflux disease.

Effects of ranitidine on quality of gastric ulcer healing compared with famotidine: a randomized, controlled, multicenter trial

Ranitidine has been found to have anti-inflammatory action as well as antisecretory action in experimental models. However, there are no reports in human gastric ulcer. The aim of this study was to investigate the effects of ranitidine compared with those of famotidine on the quality of gastric ulcer healing. We randomly assigned 69 consecutive patients with gastric ulcers to ranitidine (n = 34) or famotidine (n = 35) for 12 weeks, with endoscopic assessment of the quality of gastric ulcer healing and histological assessment of gastric mucosa 12 weeks after treatment started. Ulcer healing rates of over 95% were very similar in the two groups. The rates of ulcer scars with a flat pattern (good-quality healing) were significantly higher in the ranitidine group than in the famotidine group (per protocol, 63.0% and 34.5%, p = 0.033). The neutrophil infiltration score in the body mucosa treated with famotidine, but not ranitidine, significantly increased after treatment. In contrast, the mononuclear cell infiltration score in the antral mucosa treated with ranitidine, but not in that treated with famotidine, had significantly decreased. In conclusion, initial therapy with ranitidine significantly improved the quality of gastric ulcer healing and the histological scores of gastric mucosa compared with famotidine.

Interrelation between HeLa-S3 cell transfection and hemolysis in red blood cell suspension using pulsed ultrasound of various duty cycles

We have studied the in vitro transfection of a plasmid DNA with the lacZ gene to HeLa-S3 cells and hemolysis in a red blood cell (RBC) suspension under pulsed ultrasound with duty cycles gamma of 10, 20 and 30% using a digital sonifier at a frequency of 20 kHz and an intensity of 6.2 W/cm(2) on the surface of a horn tip. Cultured HeLa-S3 cells in suspension were exposed to pulsed ultrasound for an apparent exposure time t' from 0 to 60 s. HeLa-S3 viability decreased as a single exponential function of the total exposure time t = gammat' with a common time constant tau = 3.8 s for three duty cycles. Transfection was evaluated by counting the number of beta-galactosidase(beta-Gal)-positive cells relative to the total number of cells. Pulsed ultrasound provided an enhanced transfer of the beta-Gal plasmid to HeLa-S3 cells, 3.4-fold as compared with that in the case of the control. The optimal transfection efficiencies were 0.75, 0.80 and 0.74% near t = tau with gamma = 10, 20 and 30%, respectively. The number ratio of beta-Gal-positive cells to the surviving cells after exposure increased with t' according to a modified logistic equation. The degree of hemolysis also increased exponentially with t' at a time constant tau' = tau(0)/gamma for the RBC suspension in physiological saline at a hematocrit concentration of 0.5% with tau(0) = 0.9 s. Thus the total exposure time for the optimal transfection efficiency was tau, that is, nearly four times of tau(0). Hemolysis in the RBC suspension may be a useful model for determining optimal transfection by pulsed ultrasound of various duty cycles.

Losartan, an angiotensin II (AT1) receptor antagonist, preserves cerebral blood flow in hypertensive patients with a history of stroke

In patients with severe hypertension, chronic heart failure or a history of stroke, the lower limit of autoregulation of cerebral blood flow (CBF) is shifted to higher levels of blood pressure (BP) than those observed in healthy subjects. The aim of pharmacotherapy for hypertensive patients with an impaired autoregulation of CBF should be to reduce BP while preserving an appropriate CBF. In the present study, 16 hypertensive patients who had had an episode of stroke more than 4 weeks previously were administered the angiotensin II (AT1) receptor antagonist losartan at daily doses of 25-100 mg for 4 weeks. Systolic and diastolic blood pressures were recorded for 24 h using an ambulatory BP monitoring system. CBF in both hemispheres of the cerebrum and cerebellum was quantified using single photon emission tomography with N-isopropyl-p-[123I]iodoamphetamine. At baseline, CBF was 29.7 +/- 6.7 ml/min/100 g in the cerebrum and 31.5 +/- 7.5 ml/min/100 g in the cerebellum. At the end of treatment, BP was lower, while CBF increased by 7.7% in the cerebrum, and remained at the baseline level in the cerebellum. Thus, CBF was preserved despite the reduction in BP. We consider the use of losartan is advantageous for hypertensive patients with a history of stroke in whom autoregulation of CBF is potentially impaired.

Value of virtual computed tomographic colonography for Crohn's colitis: comparison with endoscopy and barium enema

BACKGROUND

Crohn's colitis, frequently accompanied by stenosis or narrowing, can be difficult to assess through conventional methods. We evaluated the usefulness of virtual computed tomographic colonography (CTC) for the detection of colonic lesions due to Crohn's disease.

METHODS

Forty-two lesions in 33 patients with Crohn's disease were examined by CTC and barium enema (BE). Twenty-two patients also were examined by colonoscopy (CS). The visualization ability of CTC was compared with those of the other two methods.

RESULTS

In the visualization of elevated lesions, there was no significant difference between CTC and BE (18 of 20, p = 0.487) or between CTC and CS (15 of 16, p = 0.99); however, ulcerative lesions were less often visualized by CTC. However, CTC enabled identification of serious lesions in the colon proximal to the stenosis in nine patients and was superior to BE and CS in terms of its ability to visualize the proximal site of the stenosis (p = 0.003).

CONCLUSION

CTC is clinically useful for the evaluation of Crohn's colitis, especially those with stenotic lesions.

Indomethacin, but not Helicobacter pylori, inhibits adaptive relaxation in isolated guinea-pig stomach

Nonsteroidal anti-inflammatory drugs (NSAIDs) and Helicobacter pylori (H. pylori) are major factors in gastritis and peptic ulcer However, the role of NSAIDs and H. pylori infection in dyspepsia remains unclear. Gastric adaptive relaxation may be related to the pathogenesis of functional dyspepsia because the response is often disturbed in dyspeptic patients. In this study, we investigated the effects of indomethacin or H. pylori water extracts on gastric adaptive relaxation. This experiment was performed using the modified method of Desai et al. Isolated guinea-pig stomach in an organ bath was monitored for intragastric pressure and volume. Adaptive relaxation was induced by gastric luminal distention. The effects of indomethacin and H. pylori on gastric relaxation were tested in this system. Indomethacin (> 1 x 10(-5) M) significantly inhibited adaptive relaxation. Indomethacin (> 3 x 10(-6) M) induced gastric relaxation in a dose-dependent fashion. However, aspirin at a concentration sufficient for cyclooxygenase (COX)-1 inhibition did not induce gastric relaxation. Preincubation with N-nitro-L-arginine methyl ester, a nitric oxide (NO)-synthase inhibitor, inhibited indomethacin-induced gastric relaxation. Adaptive relaxation was not affected by H. pylori water extracts. In conclusion, indomethacin inhibited adaptive relaxation via prior gastric relaxation. NO production, but not COX-1 inhibition, may be involved in this effect of indomethacin. H. pylori water extracts may not have direct effects on adaptive relaxation. Inhibition of adaptive relaxation may be one of the major mechanisms underlying NSAID-induced dyspepsia.

Effects of ecabet sodium, an antiulcer drug, on gastric adaptive relaxation in isolated guinea-pig stomachs

Disturbances in the reservoir function of the stomach may cause epigastric fullness or early satiety, which are the main symptoms in patients with dysmotility-like functional dyspepsia. Gastric adaptive relaxation is involved in the reservoir function of the proximal stomach. Ecabet sodium, synthesized from abietic acid, is widely used in Japan as an antiulcer drug. The purpose of this study was to evaluate the effects of ecabet on gastric adaptive relaxation in isolated guinea-pig stomachs. Changes in intragastric volume and pressure were recorded in the presence of atropine and guanethidine. Gastric adaptive relaxation was triggered by luminal distention. Ecabet at the dose of 20 mmol/l in solutions at two pHs (pH 3.0 and 7.4) significantly lowered the threshold pressure needed for such relaxation and increased intragastric volume, but lower doses had little or no effect. The results suggested that this antiulcer drug might improve symptoms in patients with dysmotility-like functional dyspepsia.

Congestion of superior mesenteric veins and small bowel mucosal injury after endoscopic treatment of esophageal varices in patients with portal hypertension

We investigated treatment-induced changes in venous return from the small bowel and small bowel intestinal mucosal injury induced by the treatment of esophageal varices in patients with portal hypertension. A total of 14 patients (age 59.8+/-9.5 years, five women and 9 men) who received prophylactic treatment of esophageal varices between December 1998 and March 1999 were investigated. Diamine oxidase (DAO) activity was measured before and after treatment. Changes in blood flow of the portal and superior mesenteric veins were investigated by Doppler ultrasonography in six patients. A significant decrease in DAO activity was observed three days after treatment (11.5+/-1.6 units/liter prior to treatment versus 8.6+/-1.6 units/liter three days after treatment; P < 0.001). Decreases in superior mesenteric and portal venous flow velocity were observed in four and three patients, respectively. In two patients with an increase in the cross-sectional area of the superior mesenteric vein with delayed venous return, a marked decrease in DAO activity was observed three days after treatment. In patients with portal hypertension, rapid reduction of pooling of portal flow caused by the treatment of esophageal varices can induce transient congestion of the mesenteric venous system which can produce some small bowel mucosal injury.

Prevalence of Helicobacter pylori infection and correlation between severity of upper gastrointestinal lesions and H. pylori infection in Japanese patients with Crohn's disease

BACKGROUND

The prevalence of Helicobacter pylori infection in Crohn's disease (CD) patients was investigated to determine whether the presence and severity of gastroduodenal lesions were related to H. pylori infection.

METHODS

Infection rates were compared between CD group (n = 90) and the control group (n = 525). Correlations between endoscopically detected lesions and H. pylori positive rates were investigated. The relationship between drug therapy and the prevalence of H. pylori infection was also analyzed.

RESULTS

H. pylori-positive rate of the 90 CD patients attending our clinic was 16.7%, significantly lower than the rate in healthy controls (40.2%) (P = 0.0001). The involvement of H. pylori infection in the gastroduodenal lesions of CD patients was also examined. The prevalence of gastroduodenal lesions in all CD patients was high, 92.2%. The lesions observed included ulcers, erosion, and "bamboo joint-like lesions" of the stomach, and ulcers, erosion, stenosis, and elevated lesions of the duodenum. None of these lesions were found to be related to H. pylori infection. However, H. pylori infection was found to exacerbate gastric ulcers (P = 0.036). The analysis of a possible relationship between a history of drug therapy and the low prevalence of H. pylori infection in CD patients showed that the prevalence of H. pylori infection was significantly lower in patients who had received antibiotics for 2 weeks or more (P = 0.002).

CONCLUSIONS

The results suggest that H. pylori infection is essentially unrelated to the gastroduodenal lesions observed in CD. It seems likely, however, that H. pylori infection may exacerbate gastric ulcers and that H. pylori can be eradicated by prolonged use of antibiotics.

[Pure red cell aplasia developing during the course of primary macroglobulinemia associated with pseudochylothorax and IgA nephropathy]

A 74-year-old man who had undergone artificial pneumothorax therapy for pulmonary tuberculosis 40 years earlier was admitted because of blurred vision, headache, and numbness of the lower limbs in October 1997. He presented with anemia and leukocytopenia with monoclonal gammopathy of IgM (kappa). His bone marrow was diffusely infiltrated with small lymphocytes, plasmacytoid lymphocytes, and plasma cells expressing IgM, kappa surface immunoglobulin. On the basis of these findings, primary macroglobulinemia (PMG) was diagnosed. CT scan of the chest demonstrated pleural effusion of the right lung encapsulated in a thickened pleura, and pseudochylothorax was diagnosed from a specimen of chyliform fluid which contained numerous cholesterol crystals and was positive for Mycobacterium tuberculosis (MT) on PCR assay. The patient's condition was also complicated by chronic renal failure due to IgA nephropathy, which may have been a consequence of the tuberculosis, possibly due to an abnormal IgA-mediated immune response to MT. The patient gradually developed pure red cell aplasia during the course, probably due to an autoimmune mechanism. Later in the course, immunoglobulin gene analysis of the malignant cells of PMG showed that they were derived from antigenically selected cells. In the context of antigenic stimulation, the role of MT antigen in the pathogenesis of PMG was of interest in this patient.

Partial lesions in the anterior forebrain pathway affect song production in adult Bengalese finches

The avian song system consists of two main parts: the descending motor pathway and the anterior forebrain (AF) pathway. The former directly controls the motor act of singing, but the role of the AF pathway in real-time song production is not understood; lesioning a nucleus in the AF pathway in adult zebra finches did not cause any notable effects. Here we show that in a related species of songbirds, the Bengalese finch, a partial lesion located in Area X, a nucleus of the avian basal ganglia that is part of the AF pathway, causes a transient but substantial song motor deficit. This is the first demonstration that the AF pathway is involved in real-time song production in adulthood.

[Participation of pharmacists in the medical team at home]

This report reviews drug consultations at patients' home and collaboration of pharmacists with medical teams over 4 years. The participation of pharmacists is necessary for home care service, because of their pharmaceutical expertise and the demands from the medical team and patients at home.

Indices for nutritional condition and thresholds for winter survival in sika deer in Hokkaido, Japan

We derived fat indices for sika deer (Cervus nippon yesoensis) in eastern Hokkaido, Japan, and estimated the probability of over-winter survival with a logistic regression model using fat indices. Kidney fat mass (KFM) appears to be an adequate index of wide range of physical conditions before the onset of severe nutritional stress. When KFM values fell below 20 g, femur (FMF) and mandible cavity fat (MCF) indices declined sharply. FMF and MCF were useful indices for detecting malnourished deer. A logistic regression model describes survival thresholds in two bone fat indices for calves (45%) and three fat indices for adult females (FMF = 25%, MCF = 30%, KFM = 20 g). These models are useful for estimating the probability of winter survival in Hokkaido sika deer.

On the antioxidant mechanism of curcumin: classical methods are needed to determine antioxidant mechanism and activity

[reaction: see structure] The antioxidant activity of curcumin (1, 7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) was determined by inhibition of controlled initiation of styrene oxidation. Synthetic nonphenolic curcuminoids exhibited no antioxidant activity; therefore, curcumin is a classical phenolic chain-breaking antioxidant, donating H atoms from the phenolic groups not the CH(2) group as has been suggested (Jovanovic et al. J. Am. Chem. Soc. 1999, 121, 9677). The antioxidant activities of o-methoxyphenols are decreased in hydrogen bond accepting media.

Colon cancer in aged captive rhesus monkeys (Macaca mulatta)

The age-related incidence of malignant neoplasia was surveyed from a total of 301 necropsy cases of rhesus monkeys ranging in age from 13-37 years performed in the Pathology Service Unit of the Wisconsin Regional Primate Research Center during the past 15 years. All our aged monkeys lived in indoor cages and were fed with monkey chow and supplemental fruits during the past decades. In this survey, we found a total of 51 malignant neoplasms, and among them 25 cases were colon cancer. The incidence of colon cancer increased with advancing age: 3.2% at 13-19 years, 9.2% at 20-25 years, 13.5% at 26-29 years, and 20.7% at 30-37 years. Most cancers were located in the cecum and transverse regions with a unicentric origin. Two multicentric cases were associated with chronic hypertrophic colitis. Precancerous polypous lesions were not found in all cases. Histologically, all cases were mucinous adenocarcinoma and had local invasion to the muscular wall. Metastasis to the mesenteric lymph nodes was found in only two cases. As in humans, colon cancer is a common outcome of aging in nonhuman primates.

Effect of the novel prostaglandin A1 derivative TEI-6363 on ROS17/2.8 cell differentiation in vitro

The effect of TEI-6363 (5-[E-4-N,N-dimethylaminophenylmethylene]-4-hydroxy-2-[1-methyl imidazole-2-ilthio]-4-[4-phenylbutyl]-2-cyclopentenone), a chemically synthesized prostaglandin A1 derivative, on cell proliferation and osteoblastic differentiation was investigated concurrently. ROS17/2.8 cells (a rat osteosarcoma-derived cell line) were treated with TEI-6363 at two concentrations, 10(-7) and 10(-6) M, and viable cells were counted to assess cytotoxic effects and determine the growth curve. After 96 h of treatment, there was no evidence of any effect of TEI-6363 on cell viability at either concentration. However, a clear inhibitory effect on cell proliferation was observed after treatment with 10(-6) M TEI-6363 for 24 h or longer. A pulse-treatment experiment showed that TEI-6363 induced the inhibition of proliferating ROS17/2.8 cells 24 h after addition. The inhibition of proliferation was associated with G1-arrest demonstrated by flow cytometric analysis, and incorporation of [3H]thymidine by ROS17/2.8 cells was decreased. Osteoblastic differentiation (assessed on the basis of increased alkaline phosphatase activity and collagen synthesis) was induced by TEI-6363 treatment at 10(-6) M following G1-arrest and inhibition of cell proliferation. These results suggest that TEI-6363 arrested the cell cycle of ROS17/2.8 cells at the G1 phase and induced osteoblastic differentiation. These results did not appear to be dependent on a marked cytotoxic effect.

Gender differences in brain volume and size of corpus callosum and amygdala of rhesus monkey measured from MRI images

While it has been established that the weight of the female rhesus monkey brain is less than that of the male, the sexual dimorphism of specific brain structures has not been well-documented. To further understand potential sex differences, we measured the whole brain volume and the size of the corpus callosum (mid-sagittal) and amygdala (largest coronal section) in MRI images from juvenile to adult male and female rhesus monkeys between 8 months and 7.2 years of age. The mean volume of the male brain was 89.2 +/- 1.9 (S.E.M.) compared to the female brain volume of 70.8 +/- 0.72 cm3. The average area of the corpus callosum increased from 8 months to 4.5 years; 0.56 to 0.93 cm2 in males and 0.45 to 0.66 cm2 in females. However, the average area of splenium is significantly greater in females (0.280 cm2), than males (0.184 cm2). The average area of the amygdala did not change with age; it was 1.07 +/- 0.037 (S.E.M.) in males and 1.08 +/- 0.022 cm2 in females. This data suggests that the whole brain volume and the size of the entire corpus callosum of young adult female rhesus monkeys are approximately 20% smaller than those of young adult males. Interestingly, the area of the splenial portion of the corpus callosum is larger in female monkeys. The size of the amygdala showed no sex difference.

COLLABORATIVE WORK TO EVALUATE TOXICITY ON MALE REPRODUCTIVE ORGANS BY REPEATED DOSE STUDIES IN RATS : 1)EFFECTS OF 2-WEEKS DAILY ADMINISTRATION OF ESTRADIOL BENZOATE

As part of a collaborative project to assess whether a 2-weeks administration period is sufficient to detect testicular toxicity of various compounds, male rats were subcutaneously administered 0, 5, 20, 50 or 100 micrograms/kg of estradiol benzoate (E2B), a known testicular toxicant, daily for 2 or 4 weeks. After 4-weeks, suppression of body weight gain, increase in the weight of the adrenal gland, and gross changes such as decrease in size of the prostate and seminal vesicles, and increase in size of the adrenal gland were observed in the 5, 20, 50 and 100 micrograms/kg groups. On histopathological examination, degeneration/necrosis of Pachytene spermatocytes, atrophy of Leydig cells, mature spermatid retention (Lee, et al., 1993) at stages IX, X and XI, and atrophy of ducts of the epididymides were also observed in the 5, 20, 50 and 100 micrograms/kg groups. After 2-weeks, the same changes were also observed with 20, 50 and 100 micrograms/kg, but not 5 micrograms/kg. These results indicate that the toxic effects of E2B are detectable by administration for 2 weeks at an appropriate dose level.