[Clinical evaluation of anticancer effect of methionine-depleting total parenteral nutrition with 5-fluorouracil and/or mitomycin C]

Methionine-depleting total parenteral nutrition (Met-deplete TPN), infusing AO-90 amino acid solution (lacking both L-methionine and L-cysteine) as a sole nitrogen source, showed synergistic effects with several antineoplastics including 5-fluorouracil (5-FU). In the recent multi-center, randomized, controlled study, advanced gastric cancer patients were randomly allocated to RT group and Control group. RT group received AO-90 amino acid solution, while Control group infused Amiparen (commercial methionine and cysteine containing amino acid solution) as protein source for 14 days' TPN with 5-FU and mitomycin C (MMC). The over all clinical response rate (PR+CR) in RT and Control groups were 26.3% and 8.1%, respectively, with significant statistical difference in both values at p = 0.015. Fourteen advanced gastric cancer patients allocated to RT and Control group randomly and received each amino acid as protein source for 7 days TPN with 5-FU administration. All cases were performed gastrectomy without waiting period, and resected material was examined the histological response. In the 7 cases of RT group, grade 2 was seen in 4 cases, grade 1-b in 1, grade 1-a in 1 and grade 0 in 1. In the 7 of Control, 3 cases were grade 1-a and the remaining 4 were grade 0. There were significant differences in both degree and incidence of the histological response at p = 0.016. A stage IV gastric cancer patient with marked liver metastasis received 2 times RT therapy with 5-FU and MMC for 14 days and undertaken gastrectomy after 22 day, waiting period. Resected gastric cancer showed grade 2 to 3 histological response, and the liver metastasis showed marked effect as PR to CR.

Morphological changes in gastric carcinoma with progression

By combining morphological two indices, namely, (1) the degree of differentiation of glandular tubules (well or poor) and (2) the amount of intracellular mucus (rich or poor), we previously classified histological types of gastric carcinoma into four types. Using this histological classification, we studied the morphological changes of gastric carcinoma according to extra-gastric invasion in 200 autopsy and 200 resected cases. In cases in which the predominant histological type in the lamina propria was "tubular differentiation--well, mucus in cytoplasm--poor," there was a greater incidence of co-existence with other histological types. In many of these cases, the predominant histological findings changed to "tubular differentiation--poor" in the subserosa, followed by direct invasion into neighboring extra-gastric tissues. In all cases in which the predominant histological type in the lamina propria was "tubular differentiation--poor," the predominant histological type in the subserosa was also "tubular differentiation--poor." To understand the mode of extension of gastric carcinoma in relation to the histological type, we must consider not only the characteristics of the predominant histological types of carcinoma but also those of co-existing types, especially in cases of "tubular differentiation--well, mucus in cytoplasm--poor."

Hydroxyapatite-clay bone fixation for loaded implants

A clay containing hydroxyapatite (HA clay), which was made by mixing HA granules (range of sizes: 0.1-0.3 mm) and a saline solution of sodium alginate, was inserted into the medullary canal of an osteotomized rabbit's tibia with a Ti-6Al-4V titanium alloy implant. Each implant had a conical portion for bearing load. The shear strength of the bone-implant interface for the implant with HA clay was significantly greater than that for the implant without HA clay 3 months postoperatively (P < .02), while there was no significant difference between the two strengths 1 week postoperatively. Under microscopic observation, the percentage of area of newly developed bone was also significantly greater for the implant with HA clay than for the implant without HA clay 3 months postoperatively (P < .04). This study suggests that HA clay encouraged adequate bone fixation of the loaded implant in 3 months, while the clay was not effective for immediate fixation.

Synergistic effect of methionine-depleting total parenteral nutrition with 5-fluorouracil on human gastric cancer: a randomized, prospective clinical trial

Methionine-depleting total parenteral nutrition (Met-depleting TPN), infusing AO-90 amino acid solution (lacking both L-methionine and L-cysteine) as a sole nitrogen source, showed synergistic effects with 5-fluorouracil (5-FU) in tumor-bearing rats and in clinical trials with gastrointestinal tract cancers. In this study, the effect of Met-depleting TPN with 5-FU upon thymidylate synthase (TS) activity was examined, and the histological effect of this treatment on human gastric cancer was evaluated. Fourteen preoperative advanced gastric cancer patients were divided randomly into two groups. Seven cases were given Met-depleting TPN for 7 days before surgery with continuous intravenous administration of 5-FU (500 mg/body per day; total 4.0 g/body) (AO-90 group). The other 7 received conventional L-methionine-containing TPN with 5-FU (control group). All patients underwent gastrectomy without complications due to these treatments. Resected materials were examined for TS kinetics, and the anti-cancer effect was also assessed histopathologically. The specimens in the AO-90 group showed marked degeneration of cancer, while almost no effect was seen in the control group. The free TS activity of carcinoma tissue in the AO-90 group was decreased and the TS inhibition rate was increased in comparison with the control group (P = 0.0165 and P = 0.0243, respectively). Met-depleting TPN appears to play a role as a biomodulator of 5-FU in human gastric cancer.

Detection of K-ras mutations in DNAs isolated from feces of patients with colorectal tumors by mutant-allele-specific amplification (MASA)

K-ras mutations are found in approximately half of all colorectal tumors examined. To explore the possibility of detecting mutated K-ras rapidly and efficiently in DNAs isolated from fecal material, we applied the mutant allele specific amplification (MASA)-PCR method to DNA from feces of patients with colorectal tumors. Among 55 colorectal adenocarcinomas or adenomas examined, 19 were found to carry K-ras mutations in codons 12 or 13. We were able to PCR-amplify DNAs isolated from feces of 15 of these 19 patients, but in only three of the fecal samples, we were able to detect the K-ras mutations corresponding to tumor DNA by MASA and ethidiumbromide staining of the gel. The carcinomas in these three cases were more than 40 mm x 40 mm in size and located in the sigmoid colon or rectum. However, we identified the K-ras mutations in fecal DNAs of additional seven patients by MASA when the gels were blotted and probed with a radio-labeled oligonucleotide; the tumors in those patients had arisen in the distal half of the colon and the smallest of these tumors was only 7 mm x 5 mm. No K-ras mutations were detectable in feces of the remaining five cases, whose tumors were relatively small and/or located in the proximal region. The results suggested that the MASA-PCR system has potential for development as a simple, rapid and noninvasive method for diagnosing the presence of colorectal tumors that carry mutant K-ras alleles, particularly tumors located in the distal colon.

[Idiopathic interstitial pneumonia (type B) with subacute progressively enlarged bullae]

A 70-year-old man with a 10-year history of seal engraving presented with exertional dyspnea and dry coughing. Chest roentgenograms showed an interstitial shadow and bilateral progressively enlarging bullae. Open lung biopsy led to the diagnosis of idiopathic interstitial pneumonia (Type B). The size of bullae usually does not change, so cases such as this are rare because the bullae continued to expand subacutely. Persistent stimulation by the inhaled A1 and Si may have played a role in the pathogenesis of this condition.

[Effect of Bacillus natto-fermented product (BIOZYME) on blood alcohol, aldehyde concentrations after whisky drinking in human volunteers, and acute toxicity of acetaldehyde in mice]

Effects of Bacillus natto-fermented product (BIOZYME) on blood alcohol and aldehyde concentrations after drinking whisky (corresponding to 30-65 ml ethanol) were studied in 21 healthy volunteers. When 100 ml of BIOZYME was orally administrated to the volunteers before drinking whisky, the time delay of both blood factors to attain maximum concentrations were observed. The maximum decrease in blood alcohol and aldehyde concentrations were about 23% and 45% (p < 0.005), respectively, at 1 hr after drinking whisky. The aldehyde lowering effect of BIOZYME was continued for at least 4 hr after whisky drinking. Concentration of the breath alcohol was also sharply decreased by BIOZYME administration. The breath alcohol concentration in the administered group (0.18 +/- 0.11 mg/l) was found to be lowered about 44% than that of the control group (0.32 +/- 0.11 mg/l) (p < 0.0005, n = 21), at 1 hr after drinking whisky. In acute toxicity experiments of aldehyde in mice (12 mmol AcH/mg), BIOZYME showed the survival effect as with alpha-D-Ala (134% increase of the living, at 40 min after i.p. administration) (p < 0.005, n = 22). These findings reveal the Bacillus natto produced BIOZYME as a reasonable, safety and useful anti-hangover agent.

Subcellular localization of the alpha and beta subunits of the acute myeloid leukemia-linked transcription factor PEBP2/CBF

Each of the two human genes encoding the alpha and beta subunits of a heterodimeric transcription factor, PEBP2, has been found at the breakpoints of two characteristic chromosome translocations associated with acute myeloid leukemia, suggesting that they are candidate proto-oncogenes. Polyclonal antibodies against the alpha and beta subunits of PEBP2 were raised in rabbits and hamsters. Immunofluorescence labeling of NIH 3T3 cells transfected with PEBP2 alpha and -beta cDNAs revealed that the full-size alpha A1 and alpha B1 proteins, the products of two related but distinct genes, are located in the nucleus, while the beta subunit is localized to the cytoplasm. Deletion analysis demonstrated that there are two regions in alpha A1 responsible for nuclear accumulation of the protein: one mapped in the region between amino acids 221 and 513, and the other mapped in the Runt domain (amino acids 94 to 221) harboring the DNA-binding and the heterodimerizing activities. When the full-size alpha A1 and beta proteins are coexpressed in a single cell, the former is present in the nucleus and the latter still remains in the cytoplasm. However, the N- or C-terminally truncated alpha A1 proteins devoid of the region upstream or downstream of the Runt domain colocalized with the beta protein in the nucleus. In these cases, the beta protein appeared to be translocated into the nucleus passively by binding to alpha A1. The chimeric protein containing the beta protein at the N-terminal region generated as a result of the inversion of chromosome 16 colocalized with alpha A1 to the nucleus more readily than the normal beta protein. The implications of these results in relation to leukemogenesis are discussed.

Hydroxyapatite clay used to fill the gap between implant and bone

A clay containing hydroxyapatite (HA) was developed for use as a filling material between an uncemented implant and bone. It consists of 55% HA granules greater than 0.1 mm in size with a homogeneous pore distribution and a porosity of 35% to 48% in a saline solution of sodium alginate (6%). Ti-6A1-4V alloy rods with smooth surfaces were implanted into the distal medullary canal of one osteotomised tibia of 32 Japanese white rabbits. Sixteen rods were inserted with HA clay and 16 without the clay to act as a control group. Six of each group were killed at one week and ten at 12 weeks postoperatively. The pull-out strength of the implants with HA clay was significantly greater at 12 weeks (p < 0.05), as was the percentage of the area of the new bone (p < 0.05). The study suggests that HA clay has an osteoconductive property, allowing adequate bone fixation across a gap at an early stage. The use of HA clay to enhance the early stability of uncemented components may help to improve the functional outcome of total joint arthroplasty.

Lymphoepithelioma-like carcinoma originating on the eyelid

An 89-year-old woman presented a rapidly growing red nodule of 5 years' duration on her left eyelid. Histologically, the entire dermis was occupied by multiple lobules of atypical tumor cell nests surrounded by inflammatory cells and fibrous stroma. The tumor cell nests were connected with the overlying epidermis and extended into the subcutaneous fat and muscles. There were no tendencies towards squamous or glandular differentiation of the tumor cells. Immunohistochemistry showed the tumor cells to be positive for keratin/cytokeratin and epithelial membrane antigen, but negative for neuron specific enolase and vasoactive intestinal polypeptide. S-100 protein-positive Langerhans cells were also found within the tumor nests. There was no apparent evidence of a primary lesion elsewhere.

Hydroxyapatite clay for gap filling and adequate bone ingrowth

In uncemented total hip arthroplasty, a complete filling of the gap between femoral prosthesis and the host bone is difficult and defects would remain, because the anatomy of the reamed intramedullary canal cannot fit the prosthesis. Therefore, it seems practical to fill the gap with a clay containing hydroxyapatite (HA), which has an osteoconductive character. The clay (HA clay) is made by mixing HA granules (size 0.1 mm or more) having a homogeneous pore distribution and a porosity of 35-48 vol%, and a viscous substance such as a saline solution of sodium alginate (SSSA). In the first experiment, the ratio of HA granules and sodium alginate in SSSA is set for the same handling properties of HA clay and polymethylmethacrylate bone cement (standard viscosity) before hardening. As a result, the ratio is set for 55 wt% of HA in the clay and 12.5 wt% of sodium alginate in SSSA (i.e., HA:sodium alginate:saline solution = 9.8:1:7). In the second study, the gap between the femoral stem and bone model is completely filled with HA clay. However, the gap is not filled only with HA granules or HA granules mixed with saline solution. In the third animal experiment, using an unloaded model, histology shows that HA clay has an osteoconductive property bridging the gap between the implant and the cortical bone without any adverse reaction. HA clay is considered a useful biomaterial to fill the gap with adequate bone ingrowth.

Hydroxyapatite clay used to fill the gap between implant and bone

A clay containing hydroxyapatite (HA) was developed for use as a filling material between an uncemented implant and bone. It consists of 55% HA granules greater than 0.1 mm in size with a homogeneous pore distribution and a porosity of 35% to 48% in a saline solution of sodium alginate (6%). Ti-6A1-4V alloy rods with smooth surfaces were implanted into the distal medullary canal of one osteotomised tibia of 32 Japanese white rabbits. Sixteen rods were inserted with HA clay and 16 without the clay to act as a control group. Six of each group were killed at one week and ten at 12 weeks postoperatively. The pull-out strength of the implants with HA clay was significantly greater at 12 weeks (p < 0.05), as was the percentage of the area of the new bone (p < 0.05). The study suggests that HA clay has an osteoconductive property, allowing adequate bone fixation across a gap at an early stage. The use of HA clay to enhance the early stability of uncemented components may help to improve the functional outcome of total joint arthroplasty.

Genomic structure of human mismatch repair gene, hMLH1, and its mutation analysis in patients with hereditary non-polyposis colorectal cancer (HNPCC)

Mutation of hMLH1, a gene involved in DNA mismatch repair, is responsible for some families carrying the hereditary non-polypotic colorectal cancer (HNPCC) syndrome. To establish a basis for presymptomatic diagnosis of HNPCC patients who carry germline mutations in this gene, we determined the exon-intron organization of hMLH1. The results indicated that hMLH1 consists of 19 coding exons spanning approximately 100 kb, and that exons 1-7 contain a region that is highly conserved in the MLH1 and PMS1 genes of yeast. We used PCR-SSCP analysis and DNA sequencing to examine the entire coding region of the MLH1 gene in DNAs of 34 unrelated cancer patients who belong to HNPCC pedigrees. Germline mutations were detectable in eight (24%) of these patients; four of them were missense mutations, one had occurred in an intron where it would affect splicing, and the remaining three were frameshift mutations resulting in truncation of the gene product downstream of the mutation site.

Intracellular immunization of human fetal cord blood stem/progenitor cells with a ribozyme against human immunodeficiency virus type 1

Successful treatment of human immunodeficiency virus infection may ultimately require targeting of hematopoietic stem cells. Here we used retroviral vectors carrying the ribozyme gene to transduce CD34+ cells from human fetal cord blood. Transduction and ribozyme expression had no apparent adverse effect on cell differentiation and/or proliferation. The macrophage-like cells, differentiated from the stem/progenitor cells in vitro, expressed the ribozyme gene and resisted infection by a macrophage tropic human immunodeficiency virus type 1. These results suggest the feasibility of stem cell gene therapy for human immunodeficiency virus-infected patients.

[Prolonged muscle paralysis after long-term infusion of muscle relaxants and large doses of steroids]

We have recently encountered three patients who developed prolonged muscle paralysis after long-term infusion of muscle relaxants and administration of large doses of steroids. Among many factors implicated in the cause of this paralysis, steroids and muscle relaxants were suggested to be most likely causative agents. In order to avoid such muscle paralysis, we must be careful to limit the dose of relaxants as small as possible. For this purpose, monitoring of neuromuscular blockade is indispensable.

Harvesting and enrichment of hematopoietic progenitor cells mobilized into the peripheral blood of normal donors by granulocyte-macrophage colony-stimulating factor (GM-CSF) or G-CSF: potential role in allogeneic marrow transplantation

To explore the use of stem/progenitor cells from peripheral blood (PB) for allogeneic transplantation, we have studied the mobilization of progenitor cells in normal donors by growth factors. Normal subjects were administered either granulocyte-macrophage colony-stimulating factor (GM-CSF) at 10 micrograms/kg/d, or G-CSF at 10 micrograms/kg/d, or a combination of G- and GM-CSF at 5 micrograms/kg/d each, administered subcutaneously for 4 days, followed by leukapheresis on day 5. Mononuclear cells expressing CD34 (CD34+ cells) were selectively enriched by affinity labeling using Dynal paramagnetic microspheres (Baxter Isolex; Baxter Healthcare Corp, Santa Ana, CA). The baseline CD34+ cells in peripheral blood before mobilization was 0.07% +/- 0.05% (1.6 +/- 0.7/microL; n = 18). On the fifth day after stimulation (24 hours after the fourth dose), the CD34+ cells were 0.99% +/- 0.40% (61 +/- 14/microL) for the 8 subjects treated with G-CSF, 0.25% +/- 0.25% (3 +/- 3/microL, both P < .01 v G-CSF) for the 5 subjects administered GM-CSF, and for the 5 subjects treated with G- and GM-CSF, 0.65% +/- 0.28% (41 +/- 18/microL, P < .5 v GM-CSF). Parallel to this increase in CD34+ cells, clonogenic assays showed a corresponding increase in CFU-GM and BFU-E. The total number of CD34+ cells collected from the G-CSF group during a 3-hour apheresis was 119 +/- 65 x 10(6) and was not significantly different from that collected from the group treated with G- and GM-CSF (101 +/- 35 x 10(6) cells), but both were greater than that from the group treated with GM-CSF (12.6 +/- 6.1 x 10(6); P < .01 for both comparisons). Analysis of the CD34+ subsets showed that a significantly higher percentage of cells with the CD34+/CD38- phenotype is found after mobilization with G- and GM-CSF. In the G-CSF group, immunomagnetic selection of CD34+ cells permitted the enrichment of the CD34+ cells in the apheresis product to 81% +/- 11%, with a 48% +/- 12% yield and to a purity of 77% +/- 21% with a 51% +/- 15% recovery in the G- and GM-CSF group. T cells were depleted from a mean of 4.5 +/- 2.0 x 10(9) to 4.3 +/- 5.2 x 10(6) after selection, representing 99.9% depletion. We conclude that it is feasible to collect sufficient numbers of PB progenitor cells from normal donors with one to two leukapheresis procedures for allogeneic transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical demonstration of bikunin, a light chain of inter-alpha-trypsin inhibitor, in human brain tumors

The presence and localization of bikunin (HI-30, or acid-stable protease inhibitor), a light chain of inter-alpha-trypsin inhibitor, was examined in 30 brain tumors employing immunohistochemical methods. The brain tumors involved 13 kinds of histological diagnosis. Bikunin immunoreactivity was detected in all of the brain tumors examined. Fibrillary staining of the glial processes was observed in astrocytoma, oligodendroglioma, and schwannoma. Intracytoplasmic staining in the interstitial cells, reactive astrocytes, and macrophages was noted in medulloblastoma, ependymoma, and meningioma. Metastatic tumors demonstrated intense immunoreactivity in the tissues surrounding the tumor cells. Neuronal cells revealed no bikunin immunoreactivity. There was no correlation between the intensity of staining and histologic type or grading of malignancy. In view of our earlier report that bikunin was present in the connective tissues around the site of cancer invasion, the above findings suggest that bikunin may play an important role in defense or repair at the tissue destruction and degeneration site.

Soluble CD4, soluble CD8, soluble CD25, lymphopoieitic recovery, and endogenous cytokines after high-dose chemotherapy and blood stem cell transplantation

Mononuclear cell preparations from peripheral blood after mobilization with hematopoietic growth factors have been shown to induce accelerated neutrophil and platelet recovery as compared with that induced by autologous bone marrow transplantation after myeloablative chemotherapy. Because these mononuclear cell products contain many immunocompetent cells other than hematopoietic progenitors, these accessory cells might contribute to the rapid immunohematopoietic reconstitution. We have monitored the concentrations of soluble CD4 (sCD4), sCD8, and sCD25; the recovery of the lymphocyte subsets and of natural killer (NK) cells; and the endogenous levels of granulocyte colony-stimulating factor (G-CSF), interleukin-3 (IL-3), IL-6, and granulocyte-macrophage-CSF (GM-CSF) in 12 patients who underwent high-dose chemotherapy supported by blood stem cells that were obtained by mobilization with chemotherapy and GM-CSF. The concentrations of both G-CSF and IL-6 peaked at 7 days after reinfusion of stem cells, and this transient elevation preceded the increase in the white blood cell count by approximately 5 to 7 days. The levels of sCD4 and sCD8 increased to a maximum on day 21, and the time to peak levels coincided with the maximum increase in white blood cell count, absolute neutrophil count, or lymphocytes. The levels of sCD25 were found to be elevated from day 7 to day 21. Statistically, the increases in sCD4, sCD8, sCD25, G-CSF, and IL-6 were highly significant, whereas there were no significant changes in IL-3 and GM-CSF. A rapid recovery of the NK activity was found in all 8 of the patients who could be monitored for this assay. Therefore, our study suggests that recovery of CD4+ cells, CD8+ cells, and NK activity coincided with that of neutrophils, which is preceded by a marked, but transient, elevation of IL-6 and G-CSF.

Cloning and sequencing of phospholipase B gene from the yeast Torulaspora delbrueckii

The extracellular phospholipase B gene from baker's yeast Torulaspora delbrueckii was cloned and sequenced. Analysis of DNA sequence data revealed an open reading frame (ORF) encoding a 649-amino acid protein, that included amino acid sequences obtained from the purified enzyme. Comparison of these sequence data with the N-terminal amino acid sequence of the enzyme indicated that this secreted protein is synthesized as a large precursor with a 21-amino acid N-terminal extension to the mature enzyme of 628 amino acids. A homology search was carried out between phospholipase B from T. delbrueckii and Penicillium notatum. The deduced amino acid sequence of the cloned phospholipase B was homologous (about 50% identity) to phospholipase B from P. notatum, and contained six conserved regions. The transcriptional level of mRNA of the phospholipase B gene was higher in the cells from early exponential and stationary phases.

Trilineage recovery by combination therapy with recombinant human granulocyte colony-stimulating factor and erythropoietin in patients with aplastic anemia and refractory anemia

Ten patients with aplastic anemia (AA) and seven patients with refractory anemia (RA) were treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF) and erythropoietin (rhEpo) in combination. rhG-CSF (5-20 micrograms/kg) and rhEpo (120-720 U/kg) were administered by s.c. injection three times a week for at least six months, and the administration was continued as maintenance therapy for as long as possible when hematological responses were observed. Six (60%) of the ten AA patients and four (58%) of the seven RA patients showed multilineage responses. Of these responders, six patients achieved trilineage recovery. While all of the responders were dependent on red blood cell transfusions and eight of them required platelet transfusions before treatment, they now no longer need transfusions of either red blood cells or platelets. A median treatment duration of 9 (range 1 to 28) months was required to achieve multilineage recovery. The responders showed an ability to maintain the multilineage recovery for 9+ to 47+ months and to tolerate long-term treatment. These results indicate that the long-term treatment with rhG-CSF and rhEpo may benefit a substantial percentage of patients with AA and RA and provide an optional therapy for these patients.

Gastric carcinoma

This article considers the significance and role of classic barium radiology in the diagnosis of gastric carcinoma and correlates it with endoscopy and other diagnostic modalities. Technical considerations for demonstrating optimum radiographic images of gastric carcinoma in terms of location, control of lumen distention, and positional setting are presented next. Finally, representative radiographic images of various morphologic types of gastric carcinoma are described and presented.

A novel antagonist, phenylbenzene omega-phosphono-alpha-amino acid, for strychnine-sensitive glycine receptors in the rat spinal cord

1. 3-[2'-Phosphonomethyl[1,1'-biphenyl]-3-yl]alanine (PMBA) is a novel glycine antagonist at strychnine-sensitive receptors. The chemical structure of PMBA, possessing both a glycine moiety and a phosphono group, is quite different from that of strychnine. 2. In the spinal motoneurone of newborn rats, glycine (100 microM-1 mM) induced depolarizing responses in a concentration-dependent manner. PMBA effectively inhibited depolarizing responses to glycine and other agonists, such as taurine and beta-alanine. The dose-response curves for glycine were shifted to the right in an almost parallel manner (pA2 value: 5.30 +/- 0.23, n = 5) by PMBA which was about 60 times less potent than strychnine (pA2 value: 7.08 +/- 0.21, n = 5) as a glycine antagonist. 3. PMBA (1-100 microM) did not interact with modulatory glycine sites on N-methyl-D-aspartate (NMDA) receptors, which suggests a high selectivity of PMBA for strychnine-sensitive glycine receptors. At considerably high concentrations (0.1 mM-1 mM), PMBA depressed responses to GABA (pA2 value: 3.57 +/- 0.24, n = 3). 4. PMBA inhibited the binding of [3H]-strychnine to synaptosomes from adult rat spinal cords; the IC50 values of PMBA, glycine and strychnine were 8 +/- 2, 9 +/- 3 and 0.08 +/- 0.04 microM, respectively (n = 5) for [3H]-strychnine (4.8 nM). 5. PMBA is a central excitant drug with relatively high potency and selectivity and should be useful as a pharmacological probe for analysing the mechanisms underlying physiological functions of glycine receptors.