Interleukin-6, tumour necrosis factor alpha and interleukin-1beta in patients with renal cell carcinoma.

As regulators of malignant cell behaviour and communication with stroma, cytokines have proved useful in understanding cancer biology and developing novel therapies. In renal cell carcinoma, patients with inflammatory reactions are known to have poor prognosis. In order to elucidate the relation between renal cell carcinoma and the host, serum levels of inflammatory cytokines, interleukin-6, tumour necrosis factor alpha, interleukin-1beta, were measured. One hundred and twenty-two patients with renal cell carcinoma and 21 healthy control subjects were studied, and serum cytokine levels were measured using a highly sensitive ELISA kit. As a result, in the control group, interleukin-6, tumour necrosis factor alpha and interleukin-1beta levels were 1.79+/-2.03, 2.74+/-0.94 and 0.16+/-0.17 pg ml(-1), respectively. In the renal cell carcinoma patients, they were 8.91+/-13.12, 8.44+/-4.15 and 0.53+/-0.57 pg ml(-1), respectively, and significantly higher. In the comparison of stage, interleukin-6 level was significantly higher in the stage IV group compared to the other stage groups including the control group, while tumour necrosis factor alpha level was significantly higher in each stage group compared to the control group. As for grade, interleukin-6 level was significantly higher in the grade 3 group compared to the control, grade 1 and grade 2 groups, while tumour necrosis factor alpha level was significantly higher in each grade group compared to the control group. All cytokines had a positive correlation with tumour size. In regard to the correlation with CRP, all cytokines had a positive correlation with CRP, while interleukin-6 had a particularly strong correlation. In conclusion, interleukin-6 may be one of the factors for the poor prognosis of patients with renal cell carcinoma. In addition, tumour necrosis factor alpha may be useful in the early diagnosis of renal cell carcinoma and post-operative follow-up.

[Effects of cernitin pollen-extract (Cernilton) on inflammatory cytokines in sex-hormone-induced nonbacterial prostatitis rats].

Cernitin pollen-extract (Cernilton, CN) is a preparation made from eight kinds of pollen and has been used for various prostatic diseases in Japan and Europe. We reported previously that CN possessed a recovery action on the sex-hormone-induced nonbacterial prostatitis in rats. To clarify the possible mechanism of action of CN, we investigated the effects of CN on inflammatory cytokines (IL-1 beta, IL-6 and TNF-alpha) in the same model. Aged Wistar rats were castrated and injected 17 beta-estradiol (0.25 mg/kg/day, s.c.) for 30 days. CN (630 and 1,260 mg/kg, p.o.) or testosterone (2.5 mg/kg, s.c.) was administered for the last 14 days of the treatment of 17 beta-estradiol. In control rats, prostatic IL-6 and TNF-alpha contents were increased approximately 2-3 fold, and acinar glandular inflammation and stromal proliferation were found histopathologically, as compared with those of intact rats. On the other hand, CN decreased the increased contents of cytokines in a dose-dependent manner. The histopathological changes mentioned above were restored in rats treated with 1,260 mg/kg. Testosterone also ameliorated them significantly. These results indicate that CN has an anti-inflammatory action, and that the inhibitory effect of CN on the prostatic inflammatory cytokine is an important factor in its action.

Antitumor effect on murine renal cell carcinoma by autologous tumor vaccines genetically modified with granulocyte-macrophage colony-stimulating factor and interleukin-6 cells.

The authors evaluted the efficacy of vaccination with murine renal cell carcinoma (Renca) secreting the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene and interleukin-6 (IL-6) gene for the treatment of Renca tumor. Murine GM-CSF and murine IL-6 genes were introduced and expressed in Renca cells (Renca-GM-CSF and Renca-IL-6). For a prevaccination study, wild-type Renca cells were injected subcutaneously into Balb/c mice that had been vaccinated three times with inactivated wild-type Renca, Renca-GM-CSF, Renca-IL-6, or a mixture of Renca-GM-CSF and Renca-IL-6 cells 7, 14, and 21 days before this tumor inoculation. For vaccination experiments, Renca tumor-bearing (8 to 10 mm) mice were injected subcutaneously weekly for 3 weeks with inactivated wild-type Renca cells, or either one or a combination of Renca-GM-CSF and Renca-IL-6. A nonvaccinated control was included in all experiments. The animals were monitored for survival and tumor development for 8 weeks. Mice inoculated with wild-type Renca alone died from the tumor within 35 days. Renca-IL-6 grew slower than wild-type Renca (p < 0.05). No tumor was produced by Renca-GM-CSF. Prevaccination with the combination of Renca-GM-CSF and Renca-IL-6 prevented subsequently inoculated wild-type Renca from forming tumors, and prevaccination with either one of them, compared with prevaccination with wild-type Renca, retarded tumor growth and prolonged survival time. Tumor-bearing mice vaccinated with wild-type Renca died within 42 days. Vaccination with Renca-GM-CSF or Renca-IL-6 alone prolonged the survival time, but only Renca-GM-CSF drastically reduced the tumor size. Vaccination with the combination of them achieved complete remission. Neither of the cytokine-secreting cells enhanced the expression of MHC class I or II molecules. Autologous tumor cell vaccine secreting GM-CSF is effective in preventing and treating established tumors. Its efficacy is enhanced by the cosecretion of IL-6.

[Experience with partial nephrectomy for renal cell carcinoma].

From Sept. 1991 to Jan. 1999, we performed partial nephrectomy on 7 patients with renal cell carcinoma. The indication was imperative for 3 patients, and elective for 4 patients. The 3 imperative cases consisted of bilateral renal cell carcinomas, a polycystic kidney disease and a contralateral atrophic kidney. All 4 patients with elective indication revealed renal cell carcinoma with a normal functioning contralateral kidney. The tumor size ranged from 1.3 cm to 6.0 cm (2.7 cm on average). The mean clamping time of renal artery was 22 minutes and mean blood loss was 400 ml. The pathological stage was pT1a in 6 patients and pT1b in one patient. Postoperative follow-up ranged from 4 months to 92 months (mean: 43 months). One patient with bilateral renal cell carcinoma died of metastases to the lungs and brain at 25 months postoperatively. The remaining 6 patients are alive without recurrence and metastasis. We obtained a good postoperative course in our selected patients with low stage. Thus it was considered that partial nephrectomy is effective against small renal cell carcinoma.

Embolotherapy for venous impotence: use of ethanol.

PURPOSE: To evaluate the usefulness of embolotherapy with ethanol for the treatment of venous impotence. MATERIALS AND METHODS: Twenty-three patients with venous impotence underwent embolotherapy. The diagnosis of venous impotence was made by means of pharmacocavernosometry and cavernosography. After exposure of the deep dorsal penile vein, a intravenous catheter was inserted directly into the deep dorsal penile vein and advanced into just front of the preprostatic plexus. Fifty percent ethanol was injected through the catheter and the endpoint of the procedure was determined based on results of venography immediately after injection. The procedure was finished when lack of venous leakage was confirmed. RESULTS: In all patients, the deep dorsal penile vein was successfully exposed surgically, the sclerosing agent successfully injected, and the endpoint successfully achieved. Immediate clinical therapeutic effect (restoration of erection) was obtained in 20 cases (87%). No severe complications were observed during or after the procedure. The follow-up period was 6-50 months. Long-term therapeutic effect was confirmed for 18 of 23 patients (78%). CONCLUSION: The authors' findings suggest that this treatment had satisfactory short-term and long-term clinical results and that longer follow-up is necessary to confirm its safety.

Epidermoid cyst arising from the spermatic cord area.

PURPOSE: We report on an epidermoid cyst arising from the spermatic cord area that was confirmed histologically after local excision. METHODS/RESULTS: Radiologic studies demonstrated a well-encapsulated solid mass in the left inguinal region, which was adjacent to the left spermatic cord. Tumor resection was then performed. Pathological examination revealed a epidermoid cyst lined with keratinized squamous epithelium. CONCLUSION: There was no recurrence observed 5 years after surgery.

Antitumor effects of Scutellariae radix and its components baicalein, baicalin, and wogonin on bladder cancer cell lines.

OBJECTIVES: To investigate the antitumor effects of Scutellariae radix and its components baicalein, baicalin, and wogonin on human bladder cancer cell lines (KU-1 and EJ-1) and a murine bladder cancer cell line (MBT-2). METHODS: Bladder cancer cells were incubated with various concentrations of the agents. Antiproliferative activity against the bladder cancer cell lines was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diplenyl tetrazolium bromide assay. In an in vivo experiment, the mice were subcutaneously injected with MBT-2 cells, and Scutellariae radix was orally administered at a dose of 2 or 10 mg per mouse one time daily for 10 days from day 11 to day 20. RESULTS: All the drugs inhibited cell proliferation in a dose-dependent manner, but baicalin exhibited the greatest antiproliferative activity. The concentration of baicalin necessary to obtain 50% inhibition was 3.4 microg/mL for KU-1, 4.4 microg/mL for EJ-1, and 0.93 microg/mL for MBT-2. For KU-1 and MBT-2, the percentage of cell survival significantly decreased (P <0.05) at a baicalin concentration of 1 microg/mL. In an in vivo experiment, antitumor effects of Scutellariae radix on C3H/HeN mice implanted with MBT-2 were investigated. All the control mice showed a progressive increase in tumor volume, reaching 2.81 +/- 0.18 cm(3) on day 20 and 5.36 +/- 0.44 cm(3) on day 25. However, when Scutellariae radix was orally administered at a dose of 10 mg per mouse one time daily for 10 days from day 11 to day 20, the tumor volume was 1.99 +/- 0.19 cm(3) on day 20 and 3.86 +/- 0.26 cm(3) on day 25, a significant inhibition of tumor growth (P <0.05). Conclusions. These results suggest that Chinese herbal medicines may become an attractive and promising treatment for bladder cancer.

Human fatty acid omega-hydroxylase, CYP4A11: determination of complete genomic sequence and characterization of purified recombinant protein.

The gene of the human fatty acid omega-hydroxylase, CYP4A11, has been isolated from a human BAC library, and its complete genomic sequence has been determined. The CYP4A11 gene spanned 12,568 bp and contained 12 exons. The known PPAR recognition elements (PPRE), which were reported to be involved in the induction of CYP4A6 by clofibric acid, were not observed within the 5'-flanking region of the CYP4A11 gene. The recombinant CYP4A11 protein expressed in Escherichia coli using the pCWOri expression vector was purified to an almost electrophoretically homogeneous state with a specific content of 6.4 nmol of P450/mg of protein. This P450 exhibited omega-hydroxylation activity toward laurate, with a turnover number of 14.7 nmol/min/nmol of P450. The apparent K(m) and V(max) values were 56.7 microM and 15.2 nmol/min/nmol of P450, respectively. It also showed omega-hydroxylation activity toward palmitate, with a turnover number of 0.78 nmol/min/nmol of P450. Although several reports from other groups described that CYP4A11 preparations catalyzed omega-hydroxylation of arachidonic acid, our purified recombinant protein exhibited no activity toward arachidonic acid nor prostaglandin A(1).

Extracorporeal shock wave lithotripsy for upper urinary tract stones using the Dornier Lithotripter Compact: an experience in Japan.

Between May 1997 and February 1998, 40 cases of renal stones and 40 cases of ureteral stones in 60 males and 20 females were treated with the Dornier Lithotripter Compact. The size of the stones ranged from 5 mm to 80 mm. Three patients required epidural anesthesia and 4 patients required a ureteral stent. Fragmentation of the stones was observed in all patients. After 1 month, the efficacy and stone free rates were 91% and 54%, respectively. After 3 months, they were 91% and 68%, respectively. There were no serious side effects such as pyelonephritis, perirenal hematomas, and massive hematuria. In conclusion, the Dornier Lithotripter Compact proved to be a safe and highly effective lithotripter for the treatment of renal and ureteral stones.

Augmentation of antitumor activity of 5'-deoxy-5-fluorouridine by thymosin fraction 5 in mouse bladder cancer cells in vitro and in vivo.

5'-Deoxy-5-fluorouridine (5'-dFUrd) is a prodrug of 5-fluorouracil (5-FUra) activated by pyrimidine nucleoside phosphorylase (PyN Pase), mainly by uridine phosphorylase (Urd Pase) in rodents and by thymidine phosphorylase (TdR Pase) in humans, which is preferentially located in tumor tissues compared to normal tissues. It has been reported that PyN Pase is induced by cytokines such as tumor necrosis factor (TNF), interleukin-1alpha (IL-1alpha) and interferon (IFN). Thymosin is a glycoprotein extract obtained from the calf thymus and is a potent immunopotentiating preparation. In this study, the antiproliferative activity of 5'-dFUrd used in combination with thymosin fraction 5 (TF5) was investigated in mouse bladder cancer cell line MBT-2 in vitro and in vivo. In vitro TF5 enhanced the activity of 5'-dFUrd by up to 4.11-fold, whereas the activity of other cytostatics such as 5-FUra, mitomycin C, adriamycin, cis-platinum, etoposide, vinblastine and methotrexate was not changed. In vivo when the effects of combination therapy with 5'-dFUrd and TF5 in C3H/HeN mice implanted with MBT2 were studied, tumor growth was not suppressed by TF5 alone while tumor growth was suppressed to some degree by 5'-dFUrd alone. However, tumor growth suppression was enhanced when 5'-dFUrd was used in combination with TF5. In order to investigate this mechanism, Urd Pase in MB2 was measured, and it was found that TF5 increased enzyme activity by up to 1.8-fold in MBT2. This increased susceptibility might be a result of the induction of Urd Pase, which is the essential enzyme for the conversion of 5'-dFUrd to 5-FUra. These results suggested that the therapeutic benefit of 5'-dFUrd would be improved by its use in combination with TF5 and the modulation of converting enzymes for antitumor prodrugs could be a novel therapeutic strategy for treating human cancers.

Immunotherapy for lung metastases of murine renal cell carcinoma: synergy between radiation and cytokine-producing tumor vaccines.

We investigated the combination therapy of local radiation of lung metastasis and vaccination with autologous tumor cells that produced interleukin (IL)-2, interferon-gamma (IFN-gamma), and granulocyte-macrophage colony-stimulating factor (GM-CSF) using the mouse Renca pulmonary metastasis model. Wild-type Renca (W/Renca) were transfected with pEF-BOS vector incorporating cDNAs for IL-2, IFN-gamma, or GM-CSF to express these cytokines. W/Renca, IL-2-producing Renca (Renca/IL-2), and IFN-gamma-producing Renca (Renca/IFN-gamma) produced subcutaneous tumor at the injection site in eight of eight, one of eight, and two of eight mice, respectively. No tumors were found in the GM-CSF-producing Renca (Renca/GM-CSF) group (zero of eight). Renca/IFN-gamma produced subcutaneous (s.c.) tumors in all Balb/c nude mice, but Renca/IL-2 and Renca/GM-CSF did not. To test the elicitation of antitumor activity, Balb/c mice were injected intravenously with 1 x 10(5) W/Renca on day 0, vaccinated, s.c., with 1 x 10(6) cells each of 5,000 rad preirradiated Renca/IL-2, Renca/IFN-gamma, and Renca/GM-CSF or 3 x 10(6) cells of preirradiated W/Renca on days 1, 7, and 14, and radiated with 300 rad to both lungs on day 5. The animals were killed on day 21 and tumor nodules in the lungs were enumerated. Neither local irradiation alone nor the combination of lung radiation and multiple vaccination with irradiated W/Renca significantly reduced the number of lung tumors. In contrast, the combination of lung radiation and the multiple vaccinations with cytokine-producing Renca cells significantly reduced the number of lung tumors. This regimen was more effective than the multiple vaccinations with cytokine-producing Renca cells alone. These studies demonstrate the efficacy of vaccination with autologous tumor cells expressing these cytokines and sensitization of the tumor target with radiation.

An aureobasidin A resistance gene isolated from Aspergillus is a homolog of yeast AUR1, a gene responsible for inositol phosphorylceramide (IPC) synthase activity.

The AUR1 gene of Saccharomyces cerevisiae, mutations in which confer resistance to the antibiotic aureobasidin A, is necessary for inositol phosphorylceramide (IPC) synthase activity. We report the molecular cloning and characterization of the Aspergillus nidulans aurA gene, which is homologous to AUR1. A single point mutation in the aurA gene of A. nidulans confers a high level of resistance to aureobasidin A. The A. nidulans aurA gene was used to identify its homologs in other Aspergillus species, including A. fumigatus, A. niger, and A. oryzae. The deduced amino acid sequence of an aurA homolog from the pathogenic fungus A. fumigatus showed 87% identity to that of A. nidulans. The AurA proteins of A. nidulans and A. fumigatus shared common characteristics in primary structure, including sequence, hydropathy profile, and N-glycosylation sites, with their S. cerevisiae, Schizosaccharomyces pombe, and Candida albicans counterparts. These results suggest that the aureobasidin resistance gene is conserved evolutionarily in various fungi.

Isolation and characterization of the aureobasidin A-resistant gene, aur1R, on Schizosaccharomyces pombe: roles of Aur1p+ in cell morphogenesis.

To study the mechanism of action of the antibiotic aureobasidin A (AbA) on yeasts, we isolated a dominant mutant of Schizosaccharomyces pombe which gave high resistance to AbA. From a genomic library of the mutant, an aur1R mutant gene conferring AbA resistance was isolated. One amino-acid mutation, a substitution of glycine with cysteine at residue 240, was responsible for the acquisition of AbA resistance. The wild-type aur1+ gene was essential for viability, and its over-expression enhanced significant resistance to AbA. The predicted protein of S. pombe aur1R was highly homologous in primary structure and hydropathy profile with that of Saccharomyces cerevisiae AUR1R isolated as an AbA-resistance gene. To analyze a role in cell growth of S. pombe aur1+, temperature-sensitive mutants (aur1ts) were obtained by random mutagenesis procedures using a modified PCR. The aur1ts mutation caused a defect in cell elongation at the non-permissive temperature and finally led to cell death. These results suggest that Aur1p was a target of the antibiotic AbA and was required in the cell elongation of cell-end tips and in the viability of S. pombe.

Left acute scrotum associated with appendicitis.

A 10-year-old boy, who had a mild inguinal hernia in his left scrotum, was referred to our clinic because of redness of the scrotal skin and tenderness of the left scrotal contents. Scrotal echography showed a hypoechoic lesion around the normal testis and epididymis. Because torsion of either the testis or testicular appendage was suspected, the scrotum was opened and 1.5 mL of purulent fluid was observed in the tunica vaginalis with inflammatory tissue around the testis and epididymis. On the first postoperative day, a low grade fever and abdominal tenderness persisted, however, the abdomen was flat and soft. There was no marked tenderness over McBurney's point, but there was moderate tenderness over Lanz's point on deep palpation. Abdominal sonography and magnetic resonance imaging revealed abscess formation between the bladder and the sacrum. With a diagnosis of perforation of the appendix, a laparotomy was performed. The inguinal hernia sac could not be observed on inspection, and it was not possible to palpate the left side because of severe adhesion due to infection. Also, the neck of the right inguinal sac could not be seen. The appendix specimen was gangrenous. On the second postsurgical day, all symptoms and signs disappeared. We present this rare condition and discuss the difficulty in establishing a diagnosis.

[Leiomyoma of the bladder: report of two cases].

We report 2 cases of leiomyoma of the urinary bladder. A 41-year-old female visited our hospital with the complaint of pollakisuria. A solid tumor of the urinary bladder was found by ultrasonography. A large shadow defect at the left-anterior wall was shown by drip infusion pyelography (DIP). Computed tomographic scan (CT) and magnetic resonance imaging (MRI) also revealed a large tumor. T1-weighted image revealed a homogeneous low intensity tumor and T2-weighted image disclosed heterogeneous low intensity tumor. Cystoscopy revealed a large submucosal tumor. Partial cystectomy was performed, and she has had neither recurrence nor metastasis for 36 months. A 32-year-old male was referred to our hospital with the complaint of macrohematuria. A solid tumor of the urinary bladder was found by ultrasonography. A shadow defect was not clearly detected by DIP. A large tumor was detected on the anterior wall by MRI. T1-weighted image showed a homogeneous low intensity tumor and T2-weighted image disclosed a high intensity tumor. Cystoscopy revealed a submucosal tumor on the anterior wall. Urine cytology did not suggest a malignancy. The biopsied specimens revealed only an inflammatory change in the mucosa. Partial cystectomy was carried out. He has had neither recurrence nor metastasis for 29 months. Histological diagnosis in both cases was leiomyoma of the urinary bladder.

[Urinary interleukin-6 and interleukin-8 in females with urethral syndrome].

Interleukin-6 (IL-6) and interleukin-8 (IL-8) are important mediators of an inflammatory response. We measured creatinine-collected urinary levels of IL-6 and IL-8 by an enzyme-linked immunosorbent assay in 21 women with urethritis syndrome as well as 20 age-matched healthy women. Urine samples were collected before treatment and after 7 or 14 days of oral administration of sparfloxacin (100 mg once daily). Urinary IL-6 level was elevated in a patient with urethritis syndrome (41.1 pg/mgCr), while urinary IL-8 levels were elevated in 8 (range 13.3 to 560 pg/mgCr). On the other hand, none of the healthy controls showed any detectable urinary level of IL-6 and IL-8. Of the 9 patients with elevated urinary IL-6 or IL-8, symptomatic improvement was obtained after chemotherapy in 8 and urinary interleukins became undetectable in 7. Urinary IL-6 and IL-8 seem to have some role in the induction of urinary symptoms.

Is a cystic lesion located at the midline of the prostate a müllerian duct cyst? Analysis of aspirated fluid and histopathological study of the cyst wall.

OBJECTIVE: In 6 patients, ranging in age from 26 to 71 years, we analyzed aspirated fluid and histologically studied cystic lesions located at the midline of the prostate. METHODS: Digital rectal examination, ultrasonography, magnetic resonance imaging, and aspiration of cystic fluid were performed to evaluate size, contents, and location of the cystic lesion. A 22-gauge needle was inserted into the cystic lesion perineally under ultrasound guidance. After extracting fluid for cytology and measurement of prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP), a specimen from the prostate involving the cystic wall was collected. Hematoxylin-eosin staining and immunohistochemical staining for PSA were performed. RESULTS: All aspirated fluid specimens were yellowish and clear without any sperm or malignant cells. The PSA levels in the fluid ranged between 90 and 670 x 10(4) ng/ml, while the PAP levels were between 168 and 4,000 ng/ml. These levels of PSA and PAP were significantly higher as compared with those in the serum. The cystic wall was lined with cuboidal or columnar epithelium. Some epithelial cells from the cystic wall showed positive immunostaining for PSA. CONCLUSIONS: Not all cystic lesions located at the midline of the prostate are müllerian duct cysts, and there is a high probability that the lesion could be a cystadenoma or a simple cyst of the prostate.

[The effectiveness of neoadjuvant chemotherapy for invasive bladder cancer].

BACKGROUND: Sixteen patients with invasive bladder cancer were received neoadjuvant methotrexate, vinblastine, pirarubicin and cisplatin chemotherapy on our planning protocol. METHODS: The tumor was evaluated after 1 course of chemotherapy by radiographic examination, urine cytology, cystoscopy and random biopsy. If the response is CR or PR, one more course of chemotherapy was performed, and cystectomy was carried out. If the response is NC or PD, cystectomy was immediately carried out. Twelve of them were underwent cystectomy and four were preserved bladder. Clinical response was evaluated by echo, CT, MRI, urinary cytology, cystoscopy and random biopsy. RESULTS: Clinical CR was observed in 25% and PR was 37.5%. Pathological CR was observed in 31.3% and PR was 37.5%. The different rate between clinical and pathological evaluations was 31.3% and the result suggests that we should find the method of more accurate staging evaluation. Four patients who were evaluated clinical CR were selected bladder-preserving. However, two of them (50%) had recurred; one had grade 3 tumor was treated by total cystectomy and the other had multiple tumors was treated by one course of M-VAC and TUR-Bt. CONCLUSION: We should consider which cases are possible to preserve bladder by investigating the tumor characteristics.

AUR1, a novel gene conferring aureobasidin resistance on Saccharomyces cerevisiae: a study of defective morphologies in Aur1p-depleted cells.

Aureobasidin A (AbA), a cyclic depsipeptide produced by Aureobasidium pullulans R106, is highly toxic to fungi including Saccharomyces cerevisiae. We isolated several dominant mutants of S. cerevisiae which are resistant to more than 25 micrograms/ml of AbA. From a genomic library of one such AUR1 mutant, the AUR1R (for aureobasidin resistant) mutant gene was isolated as a gene that confers resistance to AbA on wild-type cells. Its nucleotide sequence showed that the predicted polypeptide is a hydrophobic protein composed of 401 amino acids, which contains several possible transmembrane domains and at least one predicted N-linked glycosylation site. Comparison of the mutant gene with the wild-type aur1+ gene revealed that the substitution of Phe at position 158 by Tyr is responsible for acquisition of AbA resistance. We suggest that the gene product of the wild-type aur1+ is a target for AbA on the basis of following results. Firstly, cells that overexpress the wild-type aur1+ gene become resistant to AbA, just as cells with an AUR1R mutation do. Secondly, disruption of the aur1+ gene demonstrated that it is essential for growth. Thirdly, in the cells with a disrupted aur1 locus, pleiotropic morphological changes including disappearance of microtubules, degradation of tubulin and abnormal deposition of chitin were observed. Some of these abnormalities are also observed when wild-type cells are treated with AbA. The abnormality in microtubules suggests that the Aur1 protein is involved in microtubule organization and stabilization.