Development of a competitive enzyme-linked immunosorbent assay for diethylcarbamazine

A sensitive and reproducible competitive enzyme-linked immunosorbent assay (ELISA) for the determination of the concentration of diethylcarbamazine (DEC) in biological fluids was developed. Since DEC has no functional group to conjugate with bovine serum albumin (BSA), N-(2-aminoethyl)-N-ethyl-4-methyl-1-piperazinecarboxamide (DEC-NH2) was first synthesized. This compound was then converted to carboxyl DEC (DEC-COOH) and conjugated to BSA and to poly-L-lysine for use as immunogen and solid-phase marker, respectively. The competitive ELISA was conducted by simultaneously incubating DEC with mouse anti-DEC antiserum over DEC-poly-L-lysine solid phase. Subsequently, the binding of anti-DEC antibody was detected by using sheep anti-mouse IgG peroxidase conjugate as a tracer. The reliability, determined by the coefficient of variation for inter and intra-assay, was satisfactory. The cross-reactivities of anti-DEC antibodies with DEC metabolites, related compounds and ivermectin were negligible. Using this assay, DEC levels were easily determined in serum of Mongolian jirds (Meriones unguiculatus) up to 4 hours following a single dose of DEC citrate base (100 mg/kg of body weight) via intraperitoneal route.

Enzymatic diagnosis of holocarboxylase synthetase deficiency using apo-carboxyl carrier protein as a substrate

We developed a simple and sensitive method for assessing holocarboxylase synthetase (HCS) activity that is based on measuring incorporation of [3H]biotin into apo-carboxyl carrier protein, a subunit of acetyl-CoA carboxylase from E. coli. Kinetic analysis of HCS from normal fibroblasts showed that the Km for biotin was 260 +/- 94 nmol/l (mean +/- S.D.; n = 5). In contrast, the Km values of HCS from two cell lines derived from patients with HCS deficiency were 7200 and 3700, clearly distinguishable from the control value. The sensitivity of this assay was so high that we were able to characterize a mutant enzyme whose activity had not been previously detected. Our method is useful for enzymatic diagnosis of HCS deficiency and characterization of HCS.

Alterations of c-fos gene methylation in the processes of aging and tumorigenesis in human liver

The state of DNA methylation in the c-fos gene was examined in human livers of different ages, cirrhosis and hepatocellular carcinoma. The degree of methylation in the intron 1 to exon 4 region increased with age, whereas all of the 10 cirrhosis samples revealed a decrease in methylation when compared to normal livers of similar ages. The 11 hepatocellular carcinomas showed varied alterations suggesting that the alteration of the c-fos gene methylation is related to aging as well as to early-step of hepatocarcinogenesis.

Metastatic epidural bony tumor causing spinal cord compression: a case report

The authors report the case of a patient with breast cancer who developed spinal cord compression due to the expansion of an epidural bony tumor from an osteoblastic vertebral metastasis into the spinal canal. Magnetic resonance imaging revealed an epidural mass that was compressing the spinal cord but that did not demonstrate the bony elements contained within the epidural mass. These bony elements were demonstrable only by computed tomography. The patient did not respond to radiotherapy but did recover after surgical decompression. Therefore, the authors recommend the use of computed tomography for patients who have osteoblastic vertebral metastases and epidural spinal cord compression diagnosed by MRI. Once an epidural bony mass expanding from a vertebral metastasis into the spinal canal is demonstrated by computed tomography, surgical decompression is indicated.

Alteration of c-fos gene methylation in human gliomas

In an attempt to find a common DNA alteration occurring in human glioma, we examined DNA methylation in 34 gliomas of various pathological grades and compared them with those in normal cerebral subcortex DNA. The total methylated cytosine levels in the genome did not differ appreciably between the tumors and the normal tissues; however, the degree of DNA methylation in several proto-oncogenes and suppressor oncogenes showed some alterations. Among them, the c-fos gene demonstrated deviation from that of normal tissues in all cases examined, suggesting that the alteration of c-fos gene methylation plays a role in the early steps of human glioma development.

Functional coupling of adenosine A2a receptor to inhibition of the mitogen-activated protein kinase cascade in Chinese hamster ovary cells

Activation of Gs-coupled receptors enhances the increase in cyclic AMP mediated by adenylate cyclases. As it has been shown that cyclic AMP inhibits the epidermal growth factor-activated mitogen-activated protein kinase (MAPK) signalling pathway, stimulation of Gs-coupled receptors may lead to the inhibition of MAPK activation. To investigate the effect of a Gs-coupled receptor on the MAPK cascade, we cloned the adenosine (Ado) A2a receptor from a guinea-pig leucocyte cDNA library, and established Chinese hamster ovary (CHO) cells stably expressing the receptor (CHOAdoA2R). The [3H]5'-N-ethylcarbamoyladenosine (NECA) binding characteristics (Kd = 91.0 +/- 5.4 nM, Bmax = 707 +/- 11 fmol/mg of protein, n = 3) and NECA-induced cyclic AMP production indicate that the cloned Ado A2a receptor was functionally expressed in the cells. In CHO cells, thrombin induced intracellular Ca2+ increase and MAPK activation through the intrinsic G-coupled receptor. In CHOAdoA2R cells, NECA partially inhibited thrombin-elicited MAPK activation. When combining NECA-treatment with 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid acetoxymethyl ester (BAPTA-AM) loading, a nearly complete inhibition of the MAPK activation occurred. Forskolin also partially inhibited the MAPK activation and synergized with BAPTA-AM, suggesting that partial inhibition of MAPK activation by NECA results from cyclic AMP production via Ado A2a receptor activation. The same synergism of MAPK inhibition between wortmannin and BAPTA-AM was observed, but not between wortmannin and NECA. These results suggest that cyclic AMP production through Ado A2a receptor inhibits thrombin-elicited MAPK activation by a Ca(2+)-independent/wortmannin-sensitive pathway in CHO cells.

Prosthetic reconstruction for periacetabular malignant tumors

This article reports the reconstruction method and functional results of a newly designed tumor hip prosthesis with a constrained joint mechanism which was used after treatment for 13 primary and 5 metastatic periacetabular malignant bone tumors. The overall 5-year survival rate for patients with primary tumors (n=13) was 50%. The local recurrence rate was 30%. More than 90% of the patients whose hips were reconstructed with the constrained tumor hip prosthesis experienced pain relief and were able to walk with a cane. No patients had greater than 3 cm shortening of the involved limb. Infection was the most serious complication. This prosthesis restored iliofemoral stability after surgical resection of periacetabular malignant tumors.

Characterization of murine stromal cell clones established from bone marrow and spleen

Stromal cell lines were established by irradiating adherent layers of bone marrow and spleen cells in Dexter-type long-term culture with X-rays. Some of these cell lines support myelopoiesis and/or B lymphopoiesis in vitro. Furthermore, the characteristics of these stromal cell lines were studied. Cytokine activity was detected in the conditioned media from all hematopoietic-supportive and non-supportive stromal cells. Quantitative reverse transcriptase-polymerase chain reaction analysis revealed that the mRNAs of macrophage colony-stimulating factor and stem cell factor, but not that of Interleukin-3, were detectable in all the hematopoietic-supportive and non-supportive stromal cell lines. The transcripts of granulocyte colony-stimulating factor, interleukin-6, interleukin-7, and leukemia inhibitory factor were expressed in a wide variety of cell lines. Most stromal cell lines synthesized mRNA of c-mpl, the ligand of which stimulates megakaryopoiesis and thrombopoiesis. These observations indicate that the pattern of mRNA expression of cytokines is not correlated with the hematopoietic-supportive ability of stromal cell lines. There was a significant difference in the efficiency of adhesion of lineage marker-negative bone marrow cells to fibroblasts and stromal cell lines. This appears to be correlated with the hematopoietic-supportive ability of the stromal cell lines.

Purification and characterization of novel trypsin-like serine proteases from mouse spleen

Novel trypsin-like serine proteases (mouse trypsin-type serine proteases 1 and 2 [MTSP-1 and -2]) were purified to homogeneity from mouse spleen. Each protease consisted of a single polypeptide with a molecular mass of about 29 kDa, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing conditions. Both were totally inhibited by diisopropylfluorophosphate, soybean trypsin inhibitor, aprotinin, antipain, and leupeptin and partially inhibited by chymostatin and dithiothreitol, suggesting that they are trypsin-like serine proteases. They hydrolyzed synthetic substrates for trypsin-like proteases but not those for chymotrypsin-like proteases, elastase and kallikrein. MTSP-1 hydrolyzed tert-butyloxycarbonyl (Boc)-Asp(OBzl)Pro-Arg-amino-4-methyl-coumaryl-7-amide (MCA) and Boc-Ile-Glu-Gly-Arg-MCA faster than Boc-Phe-Ser-Arg-MCA. On the other hand, MTSP-2 hydrolyzed Boc-Phe-Ser-Arg-MCA most rapidly, with a specific activity 15 times higher than that of MTSP-1. The N-terminal amino acid sequence of MTSP-1 was Ile-Val-Gly-Gly-Tyr-Thr-His-Leu-Asp-Asn-Gln-Val-Pro-Tyr. This sequence was 71% homologous with the N-terminal of bovine trypsin. The Boc-Phe-Ser-Arg-MCA hydrolyzing activity of mouse spleen significantly (p < 0.01) increased to about 1.5-fold the basal activity 2 weeks after an injection of Freund's complete adjuvant, suggesting that these proteases are involved in the immune response.

[Intracavitary bacillus Calmette-Guerin therapy for upper tract transitional cell carcinoma]

Four patients with upper urinary tract transitional cell carcinoma were treated with bacillus Calmette-Guerin (BCG) via a percutaneous nephrostomy tube or a retrograde ureteral catheter. A 68-year-old female and an 80-year-old male had carcinoma in situ (CIS) in the left upper urinary tract (cases 1 and 2). A man aged 47 had CIS in the left upper urinary tract, bladder, and prostatic urethra (case 3). CIS in the left upper urinary tract was identified in a woman aged 63 with chronic renal insufficiency (case 4). Two patients (cases 1 and 2) responded to this therapy. In the other two patients nephrectomy was performed due to residual tumor. There were extensive tuberculous granulomas in the kidneys. In one resected kidney (case 4) carcinoma had invaded the renal parenchyma. The reviewed literature showed that BCG perfusion therapy was effective in 71% (27 of 38 renal units) for the upper urinary tract tumors and that there were 5 cases of severe complication, including sepsis in 2, high fever in 2, and ureteral stricture in 1. Based on the fact that the kidney receives a profuse blood supply and that the renal pelvis and ureter have a thin wall, careful management is mandatory to prevent severe adverse effects and insidious tumor progression.

Radiation therapy for patients with xeroderma pigmentosum

Our experience reported here, as well as a review of the literature, suggests that radiation therapy can be used in the palliative treatment of XP-related malignancy. However, radiation therapy should be used with caution in XP patients with an anticipated prolonged life expectancy, because the late side effects of ionizing radiation in XP are not well known.

Simple and sensitive enzyme-linked immunosorbent assay for ivermectin

A sensitive and reproducible enzyme-linked immunosorbent assay (ELISA) for the determination of the concentration of ivermectin (IVM) in biological fluids was developed. A conjugate of IVM on bovine serum albumin and poly-L-lysine was used to produce antibodies in rabbits and served as a solid-phase marker for titration of antibodies, respectively. The competitive ELISA was conducted by simultaneously incubating IVM and IVM-biotin conjugate with anti-IVM antiserum over goat anti-rabbit IgG (Fc) and then determining the amount of bound IVM-biotin with avidin-peroxidase conjugate as a tracer. The coefficient of variation for the assay was less than 10% in the range of 0.3-10 ng/ml. The limit of detection was 0.1 ng/ml. The cross-reactivities of anti-IVM antiserum with some anthelmintic drugs were negligible. Using this ELISA, serum levels of IVM were easily determined in Mongolian jirds (Meriones unguiculatus) up to 72 hr following a single oral dose of 500 microgram/kg of body weight.

The effects of xylazine on intrauterine pressure, uterine blood flow, maternal and fetal cardiovascular and pulmonary function in pregnant goats

To investigate the effects of xylazine on pregnant goats, xylazine induced changes in heart rate (HR), arterial blood pressure (ABP) and arterial blood pH and gases in the mother and fetus, as well as changes in intrauterine pressure (IUP) and uterine blood flow (UBF), were studied using a chronic preparation model of pregnant goats. Intramuscular administration of xylazine (0.2 mg/kg b.w.) caused a marked decrease in HR and ABP of the mother, which remained significantly reduced up to 120 min. In the fetus, a significant decrease in HR and a significant increase in ABP were recorded after only 5 min. Significant decreases of maternal arterial blood pH and oxygen partial pressure (Po2) were observed up to 120 and 30 min after the injection, respectively. Fetal arterial blood pH and Po2 also decreased, but these changes were milder and less persistent than those of the mother. Within 2 to 5 min after the administration of xylazine, IUP began to increase and remained high for about 15 min. Thereafter, there was a frequent periodic increase in IUP. After 5 min, UBF decreased significantly and remained low up to 120 min. A fall in UBF was associated with a rise in IUP. These findings suggested that administration of xylazine to pregnant goats results in a decrease in UBF arising from the induction of uterine contractions, a decrease in circulating blood volume, hypoxemia and acidosis in the mother.

Phosphorylation of c-Jun stimulated in primary cultured rat liver parenchymal cells by a coplanar polychlorinated biphenyl

Phosphorylation of c-Jun was stimulated in primary cultured rat liver parenchymal cells by treatment with a coplanar polychlorinated biphenyl congener, 3,3'4,4'5-pentachlorobiphenyl (PenCB), as well as by epidermal growth factor, but was not stimulated by the non-coplanar form. However, the amount of c-Jun mRNA did not increase with PenCB treatment. PenCB may activate a signal-transducing pathway consisting of protein kinases.

Changes in platelet kinetics after a partial splenic arterial embolization in cirrhotic patients with hypersplenism

We performed a partial splenic arterial embolization in 22 patients with cirrhosis associated with thrombocytopenia and then evaluated the changes in platelet kinetics after undergoing the procedure using 111In-tropolone-labeled platelets. The controls consisted of eight chronic hepatitis patients who showed a normal platelet count and normal spleen size. The mean splenic infarction ratio after the procedure was 54.9%. A platelet kinetics study was performed before and 2 months after the procedure. Before the procedure, the cirrhotic patients showed increases in the splenic volume and the spleen/liver uptake ratio of the 111In-labeled platelets on both the third and seventh days, and a decrease in the platelet recovery compared with the controls, which suggested an increased platelet pool in the spleen. In addition, the platelet survival time in cirrhotic patients was shortened, whereas the platelet-associated immunoglobulin G (PA-IgG) was higher than that of the controls, which suggested the involvement of immunologic mechanisms in the thrombocytopenia. With an increase of the platelet count after a partial splenic arterial embolization, the spleen/liver uptake ratio of the 111In-labeled platelets decreased, whereas the platelet recovery increased. Furthermore, the platelet survival time was prolonged, whereas the PA-IgG decreased. The platelet count showed a positive correlation with the platelet survival time and a negative correlation with PA-IgG before and after the procedure. These results suggest that a transcatheter splenic arterial embolization not only may reduce the increased platelet pool in the spleen but also may improve the thrombocytopenia induced by immunologic mechanisms in patients with cirrhosis.

Antifungal azoxybacilin exhibits activity by inhibiting gene expression of sulfite reductase

Azoxybacilin, produced by Bacillus cereus, has a broad spectrum of antifungal activity in methionine-free medium and has been suggested to inhibit sulfite fixation. We have further investigated the mode of action by which azoxybacilin kills fungi. The compound inhibited the incorporation of [35S] sulfate into acid-insoluble fractions of Saccharomyces cerevisiae under conditions in which virtually no inhibition was observed for DNA, RNA, or protein synthesis. It did not interfere with the activity of the enzymes for sulfate assimilation but clearly inhibited the induction of those enzymes when S. cerevisiae cells were transferred from rich medium to a synthetic methionine-free medium. Particularly strong inhibition was observed in the induction of sulfite reductase. Northern (RNA) analysis revealed that azoxybacilin decreased the level of mRNA of genes for sulfate assimilation, including MET10 for sulfite reductase and MET4, the transactivator of MET10 and other sulfate assimilation genes. When activities of azoxybacilin were compared for mRNA and enzyme syntheses from MET10, the concentration required for inhibition of transcription of the gene was about 10 times higher (50% inhibitory concentration = 30 micrograms/ml) than that required for inhibition of induction of enzyme synthesis (50% inhibitory concentration = 3 micrograms/ml). The data suggest that azoxybacilin acts on at least two steps in the expression of sulfite reductase; the transcriptional activation of MET4 and a posttranscriptional regulation in MET10 expression. We conclude that azoxybacilin exhibits antifungal activity by interfering with the regulation of expression of sulfite reductase activity.

[Cloning of the holocarboxylase synthetase cDNA and identification of mutations prevalent in Japanese HCS-deficient patients]

Holocarboxylase synthetase (HCS) plays an essential role in biotin utilization in cells and its deficiency causes biotin-responsive multiple carboxylase deficiency in humans. We have cloned the human HCS cDNA, which maps to chromosome 21q22.1. Two mutations in the HCS genes of Japanese patients with HCS deficiency have been identified: a transition from T to C which causes an amino acid substitution of proline for leucine at position 237 (L237P) and A single guanine base deletion (delta G1067) followed by premature termination. Transient expression in cultured fibroblasts from a patient after site-directed mutagenesis showed that the L237P mutation was responsible for decreased HCS activity. Hybridization analysis using allele-specific oligonucleotide probes demonstrated that the prevalence of the mutations--L237P and delta G1067--was 50% and 30%, respectively, among Japanese patients with HCS deficiency.

Recurrent placental site trophoblastic tumor of the uterus: clinical, pathologic, ultrastructural, and DNA fingerprint study

Placental site trophoblastic tumor is a rare disease. Most benign cases of this disease show a few mitotic figures of the tumor while recurrent cases usually have more than 5 mitoses per 10 high-power fields. The present case was primarily treated by hysterectomy and chemotherapy and had 2 mitoses in 10 high-power fields. After 1 years and 4 months of therapy the patients was diagnosed as ovarian metastasis because of gradually increasing serum beta-human chorionic gonadotropin (hCG) level and abnormally high fluid levels of beta-hCG and human placental lactogen (hPL) punctured from her cystic ovarian tumor. This recurrent case was further treated with another regimen of chemotherapy for 7 courses, and the serum beta-hCG level had decreased at present. This report describes the recurrent case and discusses the histology of a few mitotic figures, electron microscopic findings, and results of the DNA fingerprint analysis of the primary tumor.

Gamma Knife radiosurgery for brain stem metastases: two autopsy cases

Early neuropathological findings were obtained at autopsy in two cases of brain stem metastasis treated with the Gamma Knife. In both cases, light microscopy radiation changes were strictly localized. Residual tumor tissue in the irradiation field showed marked degenerative changes including multinuclear cells, atypical nuclei and vacuolar degeneration. A characteristic finding in the irradiation field was fibrosis associated with hyalinized and thickened vessels. In more peripheral regions, demyelination and vacuolar degeneration were seen. This is the first report demonstrating extravascular fibrosis in the irradiated field following radiosurgery.

Possible roles of medullasin in nifedipine-induced human gingival overgrowth

In order to clarify a possible pathophysiological role of medullasin, a neutrophil elastase-like proteinase, in nifedipine (NF)-induced gingival overgrowth, the distributions of medullasin-positive cells immunostained in specimens from patients with NF-induced gingival overgrowth and chronic marginal gingivitis were compared in three different biopsy areas. Twenty gingival biopsies were obtained from five patients with gingival overgrowth and 20 biopsies from another five patients with chronic marginal gingivitis. In the marginal gingivitis group, the mean percentage of positive cells in the vicinity of pocket epithelium (zone I) was significantly higher than in the areas of connective tissue of the mid-portion (zone II) and adjacent to oral epithelium ( zone III) (p < 0.05). In the gingival overgrowth group, on the contrary, the positive cells significantly increased in zone II as compared with zones I and III (p < 0.05). Further, medullasin-positive cells of zones II and III in the overgrowth group had infiltrated more extensively than those in the gingivitis group (p < 0.001), indicating the participation of this enzyme in the mechanism of NF-induced gingival overgrowth. These observations suggest that medullasin may play a part in NF-induced overgrowth both in host defence and in immunoregulation, possibly cytotoxically.

Identification of two isoforms of mouse neuropeptide Y-Y1 receptor generated by alternative splicing. Isolation, genomic structure, and functional expression of the receptors

Two cDNA clones homologous with human neuropeptide (NP) Y-Y1 receptor have been isolated from a mouse bone marrow cDNA library. One was thought to be the cognate of the human NPY-Y1 receptor, termed Y1 alpha receptor, and the other form, termed Y1 beta receptor, differed from the Y1 alpha receptor in the seventh transmembrane domain and C-terminal tail. Analysis of the mouse genomic DNA showed that both receptors originated from a single gene. The different peptide sequences of the Y1 beta receptor were encoded by separate exons, hence, these receptors were generated by differential RNA splicing. High affinity binding of [125I]NPY to each receptor expressed in Chinese hamster ovary (CHO) cells and sequestration of [125I]NPY after binding to each receptor were observed. In the CHO cells expressing the Y1 alpha receptor, intracellular Ca2+ increase, inhibition of forskolin-induced cAMP accumulation, and mitogen-activated protein kinase (MAPK) activation were observed by stimulation of NPY, and these responses were abolished by pretreatment with pertussis toxin. Since wortmannin completely inhibited NPY-elicited MAPK activation, we speculate that wortmannin-sensitive signaling molecule(s) such as phosphoinositide 3-kinase may lie between pertussis toxin-sensitive G-protein and MAPK. In contrast, these intracellular signals were not detected in CHO cells expressing the Y1 beta receptor. Northern blots and reverse transcriptase-polymerase chain reaction analyses indicated that the Y1 alpha receptor was highly expressed in the brain, heart, kidney, spleen, skeletal muscle, and lung, whereas the Y1 beta receptor mRNA was not detected in these tissues. However, the Y1 beta receptor was expressed in mouse embryonic developmental stage (7 and 11 days), bone marrow cells and several hematopoietic cell lines. These results suggest that the Y1 beta receptor is an embryonic and a bone marrow form of the NPY-Y1 receptor, which decreases in the expression during development and differentiation.

Molecular analysis of holocarboxylase synthetase deficiency: a missense mutation and a single base deletion are predominant in Japanese patients

Holocarboxylase synthetase (HCS) deficiency is an inherited disease of biotin metabolism characterized by a unique pattern of organic aciduria, metabolic acidosis, and skin lesions. By analysis of five patients in four unrelated families, two mutations were identified: a transition from T to C which causes an amino-acid substitution of proline for leucine at position 237 (L237P) and a single deletion of guanine (delG1067) followed by premature termination. One patient was homozygous for the L237P mutation, three patients in two families were compound heterozygotes of the missense and deletion alleles, and the other patient was heterozygous for the L237P mutation. Inheritance was successfully demonstrated in all of the patients' families by a modified PCR followed by restriction enzyme digestion. The two mutations accounted for seven of eight mutant alleles, while neither mutation was detected in 108 normal healthy Japanese children (216 alleles). Transient expression in cultured fibroblasts from a patient showed that the L237P mutation was responsible for decreased HCS activity. These results suggest that the L237P and delG1067 mutations are frequent disease-causing mutations in Japanese patients with HCS deficiency. This PCR-based technique may therefore be useful for detecting mutations among Japanese patients.

Monoclonal antibody against an amniotic protein carrying ABH blood group epitopes and its forensic application

A mouse monoclonal antibody against an amniotic protein carrying ABH antigenic epitopes was established. BALB/c mice were immunized by an amniotic protein of molecular weight over 200 kDa, which had proved to be the carrier protein of ABH blood group epitopes by analysis with SDS-PAGE and immunoblotting. The antibody, ASP-1, was directed to the amniotic carrier protein without affecting the ABH blood group antigenicity, and did not cross-react with other body fluids which included blood, saliva, semen, urine or vaginal secretion. The immunoglobulin class of ASP-1 was IgG1 with a titer of 1 : 1,600. ASP-1 was used to detect the ABH blood group of amniotic fluid by the sandwich ELISA in which wells of plates were coated with ASP-1, and the ABH blood group of the captured protein was detected with mouse IgM anti-A and -B antibodies and enzyme conjugated anti-mouse IgM. The sandwich ELISA could successfully detect the blood group of amniotic fluid in mixed body fluids.

[Verification of rotational conformation radiotherapy using megavoltage CT scanning]

Although portal imaging is a promising method of verification during static multi-port irradiation, it cannot be applied directly to dynamic irradiation such as rotational conformation with multi-leaf collimator movement. A real-time beam monitoring system based on megavoltage computed tomography scanning has been developed to establish a verification method for the rotational conformation technique. The exit beam through the patient is extracted by the same detector unit as that used for megavoltage scanning during the actual treatment. The beam edge is defined as the 50% level of the maximum dose of the detector array. Megavoltage computed tomography is done after patient setup and just prior to the actual irradiation. Detected beam pathways are overlaid on this image approximately every 1 sec. Therapists can monitor the correlation between the target and actual beam pathways on a real-time computer display. The accuracy of field edge detection has been proven to be less than 2 mm from various measurements. Field errors were identified in two of 54 sessions using this method. Although several limitations remain to be solved, the method presented is an useful tool for treatment verification of high accuracy radiation therapy, particularly rotational conformation irradiation.