Pamidronate treatment in patients with tumor-associated hypercalcemia: pharmacological effects and pharmacokinetics

The purpose of this study was to investigate the effects of pamidronate, a second generation bisphosphonate, on the change in calcium homeostasis in patients with tumor-associated hypercalcemia. Eight patients with tumor-associated hypercalcemia received intravenous infusion of pamidronate (45 mg) and their high mean serum calcium concentration significantly decreased from 3.56 mmol/L to 2.62 mmol/L7 days after treatment. Serum intact PTH before treatment had been suppressed to below normal in all patients but returned to normal range in six patients within 7 days after treatment. Urinary PTH related peptide (PTHrP) excretion before treatment had been elevated in seven patients and then significantly increased further after pamidronate therapy. The serum bone Gla protein concentration was not apparently changed by the treatment. Pamidronate in serum was rapidly eliminated after the treatment and urinary excretion reached a plateau on the second day (13.8% of the administered dose), suggesting that the major portion of the infused dose had been distributed to the bone and other tissues. These findings suggest that pamidronate has a potent hypocalcemic effect and that PTHrP production in malignant tumors could be affected by pamidronate therapy.

Prevalence of intestinal helminthic infections in Kao District, north Halmahera, Indonesia

A parasitological survey was conducted on the inhabitants of six villages of Kao District, Halmahera Island, North Maluku, Indonesia, in July 1993. A total of 422 fecal samples were examined by using Kato-Katz thick smear, modified Harada-Mori culture and formalin ether concentration techniques. Seven nematode species, ie Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis, Enterobius vermicularis and unidentified rhabditoids of free-living nature, were detected. Trematode and cestode infection was not proven. Necator americanus was the predominant species of hookworm. Soil-transmitted nematode infections were highly prevalent. Among the young inhabitants aged less than 15, positive rates of Ascaris, Trichuris and hookworm infections were 32.7, 52.7 and 68.6%, respectively. Among the people aged 15 or more, the positive rate for hookworm (85.9%) was much higher than that for Ascaris and Trichuris (13.5 and 40.5%, respectively). Egg count revealed that more than 90% of inhabitants with Trichuris or hookworm had light infections. The latrines in the surveyed area seemed to have only limited effects on the improvement of the parasitological status because the prevalence of Trichuris infections was much higher in a village where most houses were provided with latrines. These conflicting conditions were considered to have been caused by many factors including the inadequate structure of the latrines.

Characteristics of human hepatocellular carcinoma cell lines (Hep-KANO) derived from a non-hepatitic, non-cirrhotic hepatitis B virus carrier

We have established two cell lines of hepatocellular carcinoma [Hep-KANO, clone 1 (CL-1) and clone 2 (CL-2)] from tissue obtained at autopsy of a hepatitis B virus (HBV) carrier without histological signs of hepatitis or liver cirrhosis. These cell lines differed considerably from each other in morphology, proliferation pattern, alpha-fetoprotein secretion, albumin synthesis, cytokine secretion, modal chromosome number and transplantability to nude mice. Histologic examinations also revealed differences between them. Amplification of N-myc, L-myc, H-ras, K-ras, N-ras, c-erb-B and c-erb-B-2 and rearrangement of p53 were not found in either of the cell lines. However, CL-1 and CL-2 showed an identical HBV-DNA integration pattern. A 4-fold amplification of c-myc was observed in CL-1, but not in CL-2. Hep-KANO cell lines, CL-1 and CL-2 may be useful in clarifying the question of whether hepatocarcinogenesis is directly caused by HBV infection.

Postantibiotic effects and postantibiotic sub-MIC effects of benzylpenicillin on viridans streptococci isolated from patients with infective endocarditis

We investigated the postantibiotic effects (PAEs) and the postantibiotic sub-MIC effects of benzylpenicillin on three strains of viridans streptococci isolated from infective endocarditis patients. The PAEs of benzylpenicillin on penicillin tolerant Streptococcus sanguis TW-70 (0.4-3.9 h), penicillin tolerant S. sanguis TW-80 (0.3-6.3 h) and nontolerant Streptococcus oralis TW-186 (0.5-3.1 h) were dependent on exposure time. The PAEs were not concentration dependent for S. sanguis TW-70 and S. sanguis TW-80 above the MIC, and for S. oralis TW-186 above 16 x MIC. The antimicrobial effects of benzylpenicillin at sub-MIC concentrations were examined in bacteria pretreated with benzylpenicillin (8 x MIC) for 2 h and compared with untreated bacteria. At the sub-MICs tested, the regrowth of pretreated S. oralis TW-186 cells was more prolonged than that of untreated cells and bactericidal action was seen only in pretreated cells. These effects (so-called 'postantibiotic' sub-MIC effects') were not observed in penicillin tolerant S. sanguis TW-70. The presence of the postantibiotic sub-MIC effect may be an important factor in determining the dosing regimen for infective endocarditis.

Stage-specific expression of alkaline phosphatase during neural development in the mouse

The expression pattern of tissue nonspecific alkaline phosphatase (TNAP) in the developing neural tube of mouse is reported. Homogeneous AP activity in the neuroepithelium becomes prominent at E8.5. At E9.5, distinctly AP-positive cells appear in the brain and spinal cord area. At stages E10.5 to E12.5, AP positivity is observed between the mesencephalon and the rhombencephalon, along the entire spinal cord and cranial nerves emerging from the myelencephalon. At E13.5, strongly AP positive fibers become prominent in the pons. At E14.5, AP expression in brain tissue is considerably reduced and there is a complete absence of AP activity in the nerve cells and glial cells of adult brain. The choroid plexus remains distinctly positive for AP expression until the adult stage. Northern blot analysis and reverse-transcriptase polymerase chain reaction amplification of RNA indicate that this AP activity results from the expression of the Akp-2 locus. This AP expression pattern is distinct from those reported for the expression of GD3, nestin, Hox 2.3, and Wnt-1 during brain development. We conclude that AP is a useful marker of a subpopulation of neuroectodermal cells present in the neural tube as early as E8.5, at which stages there are no other AP positive intraembryonic cells except PGCs.

Early detection of successful coronary reperfusion based on serum myoglobin concentration: comparison with serum creatine kinase isoenzyme MB activity

The usefulness of serum myoglobin (Mb) concentration for early detection of successful reperfusion was compared with that of creatine kinase isoenzyme MB (CKMB) activity in 49 patients with acute myocardial infarction. To determine accurately the time of reperfusion, we performed coronary angiography every 5 minutes during reperfusion therapy. Reperfusion was obtained in 32 patients (reperfused group) but not in 17 patients (nonreperfused group) until 60 minutes after the initiation of reperfusion therapy. Blood samples were taken before and 15, 30, and 60 minutes after the angiographic confirmation of reperfusion in the reperfused group. In the nonreperfused group, samples were taken before and 15, 30, and 60 minutes after the initiation of treatment. We calculated the Mb ratio (value after reperfusion or treatment initiation to value before) and CKMB ratio (value after to value before). When values > 2.4 for the Mb ratio or > 2.0 for the CKMB ratio were used as the criteria for reperfusion within 60 minutes after initiation of treatment, the sensitivities were 91% and 56% at 15 minutes after reperfusion, 97% and 84% at 30 minutes, and 100% and 100% at 60 minutes, respectively. For each ratio the specificity of detection was 100% at all times evaluated. Thus the Mb ratio accurately detected the success of reperfusion as early as 15 minutes after reperfusion and may be more useful than the CKMB ratio for detecting the success of reperfusion within 30 minutes.

Hasanuddinia maxomyos n. gen., n. sp. and Heligmonoides musseri n. sp. (Nematoda: Heligmonellidae) collected from endemic murines of Sulawesi, Indonesia

Two new nematodes belonging to the subfamily Nippostrongylinae (Nematoda: Trichostrongyloidea: Heligmonellidae) are described based on specimens from endemic murines of Sulawesi, Indonesia: Hasanuddinia maxomyos n. gen., n. sp. from Maxomys musschenbroekii and Eropeplus canus, and Heligmonoides musseri n. sp. from M. musschenbroekii, E. canus, and Margaretamys elegans. Hasanuddinia is closest to Rattusstrongylus of Malaysian rats in lacking a carene and in having a lateromedian gradient in the size of the synlophe ridges in the ventral side of the midbody but is distinguished in that the dorsal ray is divided in the distal half. Heligmonoides musseri most resembles H. bulbosus of Maxomys whiteheadi of Malaysia in having a carene supported by slender ridges of which the proximal portion is not thickened but is distinguished in having longer externodorsal rays and longer spicules. The ancestors of the present Sulawesi nematodes seem to have originated on the southeast Asian continent, were introduced to Sulawesi with the dispersal of some murines, and subsequently speciated.

[A clinicopathological study of renal hemodynamics in patients with systemic lupus erythematosus]

We evaluated the clinical value of the glomerular filtration rate (GFR) and renal plasma flow (RPF) in patients with systemic lupus erythematosus (SLE). All of the patients fulfilled the criteria for SLE of the American Rheumatism Association and were divided into two groups by the criteria for disease activity. GFR and RPF were simultaneously measured by the standard clearance technique using sodium thiosulfate and sodium paraaminohippurate, respectively. Ninety-six clinically active patients and 60 inactive patients underwent one clearance study. In 36 other patients, repeated clearance studies were undertaken on two occasions during the period from the active to inactive phase. The mean RPF was 590.3 +/- 213.7 ml/min in 132 active patients and 485.7 +/- 184.0 ml/min in 96 patients without disease activity (p < 0.01), whereas the mean GFR was comparable between the two groups. In active SLE, the mean GFR in 76 patients with proteinuria was 76.0 +/- 38.2 ml/min as compared with 104.8 +/- 34.3 ml/min in 56 patients without proteinuria (p < 0.01); however, there was no significant difference in the mean RPF between the two groups. A fall in GFR was frequently observed in patients with class IV lupus nephritis. In contrast, there was no significant difference in the mean RPF between class IV patients and the patients in the other classes. As a result, a marked decrease in the filtration fraction (FF) was frequently observed in class IV lupus nephritis, irrespective of the use of diuretics or antihypertensive agents. Semiquantitative histological analyses revealed that mesangial proliferative changes were more responsible than glomerular sclerotic changes for these hemodynamic features.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning of a water channel homolog expressed in brain meningeal cells and kidney collecting duct that functions as a stilbene-sensitive glycerol transporter

In searching for a basolateral membrane water transporter in rat kidney with homology to channel forming integral protein (CHIP28), water channel-collecting duct (WCH-CD), and mercurial-insensitive water channel (MIWC), we cloned a new member of the major intrinsic protein family (GLIP, GLycerol Intrinsic Protein). GLIP cDNA had an 855-base pair open reading frame encoding a 30.5-kDa protein with 19-23% amino acid identity to the water channels and 36% identity to the bacterial glycerol facilitator GlpF. Northern blot analysis showed a 5.5-kilobase mRNA encoding GLIP in kidney, brain, and lung; RT-PCR/Southern blot analysis indicated expression of GLIP in kidney, brain, lung, eye, colon, stomach, and skeletal muscle, but not in heart, liver, and spleen. In situ hybridization in rat kidney showed GLIP mRNA expression in medullary collecting duct. Immunofluorescence with a peptide-derived polyclonal antibody showed GLIP protein expression in basolateral membrane of kidney collecting duct principal cells and brain meningeal cells. Functional measurements in Xenopus oocytes expressing GLIP cRNA showed a > 20-fold increase in [3H]glycerol uptake compared with water-injected oocytes; glycerol uptake was inhibited 88% by diisothiocyanodisulfonic stilbene (0.2 mM) and 36% by phloretin (0.25 mM). GLIP did not function as a transporter for water, urea, inositol, glucose, lactate, and monovalent ions. Glycerol uptake in oocytes expressing CHIP28 and MIWC was not different from that in water-injected controls. GLIP represents the first mammalian water channel homolog that selectively transports a solute other than water. The physiological substrate(s) and role(s) of GLIP remain to be elucidated.

[A clinical study of renal hemodynamics in patients with lupus nephritis]

This study was designed to evaluate the clinical significance of glomerular filtration rate (GFR) and renal plasma flow (RPF) in 122 patients with lupus nephritis. All patients had definite clinical evidence of active lupus nephritis, including urinary and immunological abnormalities. The average RPF was 634.5 +/- 171.4 ml/min in systemic lupus erythematosus patients and 537.4 +/- 141.9 ml/min in 37 age-and sex-matched patients with primary glomerular disease (PGD) (p < 0.01). A fall in GFR, accompanied by massive proteinuria and hypocomplementemia, was observed frequently in patients with class IV lupus nephritis (diffuse proliferative GN). In contrast, RPF did not change in most patients except in some with increased RPF. No correlation was noticed between RPF and proteinuria or immunological abnormalities. As a result, a marked fall in filtration fraction (FF) was observed frequently in class IV lupus nephritis, and was correlated significantly with urinary and immunological abnormalities. Follow-up data during treatment in the active to inactive phases (average 7.8 months) were available for 39 patients. The average GFR increased significantly from 56.9 +/- 31.4 ml/min in the pre-treatment stage to 74.5 +/- 26.9 ml/min in the post-treatment stage, accompanied by an improvement in proteinuria and hypocomplementemia. On the other hand, RPF decreased significantly from 521.3 +/- 217.1 to 437.6 +/- 156.2 ml/min, so that FF increased significantly as the renal and immunological parameters normalized. Additionally, the renal function was evaluated in 11 patients during the exacerbation of lupus nephritis.(ABSTRACT TRUNCATED AT 250 WORDS)

CRK protein binds to two guanine nucleotide-releasing proteins for the Ras family and modulates nerve growth factor-induced activation of Ras in PC12 cells

It has been reported that growth factors activate Ras through a complex of an adaptor type SH2-containing molecule, Grb2, and a Ras guanine nucleotide-releasing protein (GNRP), mSos. We report on the involvement of another adaptor molecule, CRK, in the activation of Ras. Overexpression of wild-type CRK proteins CRK-I and CRK-II enhanced the nerve growth factor (NGF)-induced activation of Ras in PC12 cells, although the basal level of GTP-bound active Ras was not altered. In contrast, mutants with a single amino acid substitution in either the SH2 or SH3 domain of the CRK-I protein inhibited the NGF-induced activation of Ras. Two GNRPs for the Ras family, mSos and C3G, were coimmunoprecipitated with the endogenous Crk proteins in PC12 cells. The association between C3G and the CRK mutants was dependent upon the presence of intact SH3. The SH2 domain of CRK bound to the SHC protein phosphorylated on tyrosine residues by NGF stimulation. The results demonstrate that, in addition to Grb2, CRK participates in signaling from the NGF receptor and that two GNRPs appear to transmit signals from these adaptor molecules to Ras.

Detection of DNA of causative agent of spotted fever group rickettsiosis in Japan from the patient's blood sample by polymerase chain reaction

The polymerase chain reaction (PCR) was applied for the etiological diagnosis of spotted fever group (SFG) rickettsiosis in Japan. Nucleotide primers derived from the 17-kDa antigen gene of Rickettsia rickettsii primed a rickettsia-specific 246-base-pair product for all of the Katayama, Abe, Misaka and Kojima strains, which we had isolated previously. Moreover, we were able to detect the same product by PCR amplification from the peripheral blood of a patient in the acute stage of the illness. The PCR method is considered to be useful for rapid etiological diagnosis of SFG rickettsiosis in Japan.

Induction of G protein-coupled peptide receptor EBI 1 by human herpesvirus 6 and 7 infection in CD4+ T cells

EBI 1, a putative lymphocyte-specific G protein-coupled peptide receptor, was induced by human herpesvirus 6 or 7 infection in CD4+ T cells, and its expression increased early after infection and reached a plateau at 48 h. The induction of the EBI 1 gene by human herpesvirus 6 or 7 infection was not mediated by soluble factors but by the virus itself. Deduced from comparisons of the amino acid sequences among members of the G protein-coupled receptor superfamily, these findings suggest that EBI 1 may be a member of the leukocyte chemotactic peptide receptor family.

Cyclodontostomum purvisi (syn. Ancistronema coronatum) (Nematoda: Strongyloidea: Chabertiidae) from rats of Kalimantan and Sulawesi, Indonesia

Cyclodontostomum purvisi Adams, 1933 (Nematoda: Strongyloidea: Chabertiidae) was collected from the ceca of Maxomys whiteheadi, Leopoldamys sabanus, and Niviventer cremoniventer of East Kalimantan and Eropeplus canus, Paruromys dominator, and Rattus hoffmanni (Rodentia: Muridae: Murinae) in South Sulawesi, Indonesia. Kalimantan and Sulawesi are new localities for this nematode, and each of the Sulawesian rats are new hosts. Presence of the external corona radiata consisting of 8 bifid elements was confirmed in Cyclodontostomum. Ancistronema coronatum Smales, 1992 is synonymized with C. purvisi. The cephalic end of Kalimantan specimens tilted dorsally more strongly than C. purvisi from Sulawesi. Cyclodontostomum purvisi seems to have a wide host range in the Murinae, being distributed widely in the area from India to Australia.

The monoamine content of the brain in the neurofilament-deficient quail, (the Quiver quail)

Changes in neurotransmission are known to take place in a variety of conditions, such as Parkinson's disease. A neurofilament-deficient mutant of the Japanese quail, named the Quiver quail, exhibits generalized quivering as a clinical sign. The content of monoamines (noradrenaline (NA), dopamine and 5-hydroxytryptamine) and the uptake and release of L-[3H]NA were measured in brain of this bird. In Quiver, the NA content in neostriatum and thalamus, and the 5-hydroxytryptamine content in neostriatum, paleostriatum and thalamus were significantly increased, in comparison with the normal quail. The dopamine content and L-[3H]NA uptake and release in the Quiver mutant were similar to those in normal quail.

Structure, function, and evolution of mouse TL genes, nonclassical class I genes of the major histocompatibility complex

In contrast to well-studied "classical" class I genes of the major histocompatibility complex (MHC), the biology of nonclassical class I genes remains largely unexamined. The mouse TL genes constitute one of the best defined systems among nonclassical class I genes in the T region of the MHC. To elucidate the function and the evolution of TL genes and their relationship to classical class I genes, seven TL DNA sequences, including one from a Japanese wild mouse, were examined and compared with those of several mouse and human classical class I genes. The TL genes differ from either classical class I genes or pseudogenes in the extent and pattern of nucleotide substitutions. Natural selection appears to have operated so as to preserve the function of TL, which might have been acquired in an early stage of its evolution. In a putative peptide-binding region encoded by TL genes, the rate of nonsynonymous (amino acid replacing) substitution is considerably lower than that of synonymous substitution. This conservation is completely opposite that in classical class I genes, in which the peptide-binding region has evolved to diversify amino acid sequences so as to recognize a variety of antigens. Thus, it is suggested that the function of TL antigens is distinct from that of classical class I antigens and is related to the recognition of a relatively restricted repertoire of antigens and their presentation to T-cell receptors.

[3H]Rolipram binding and phosphodiesterase activity in neuroblastoma N18TG-2 and glioma C6Bu-1

To clarify the functional significance of type IV phosphodiesterase (PDEIV) in neurons and glia cells [3H]rolipram binding and phosphodiesterase (PDE) activity were examined in cytosol and membrane fractions of neuroblastoma N18TG-2 and glioma C6Bu-1 cells. [3H]Rolipram binding was highly observed in cytosolic fractions of N18TG-2 compared to C6Bu-1. Binding was hardly observed in membrane fractions of both types of cells. Rolipram strongly (70%) inhibited the hydrolytic activity of cAMP in cytosolic fractions of N18TG-2. The activity in cytosol fractions of C6Bu-1 was slightly (20%) inhibited by rolipram. These results suggest that PDEIV plays important roles in neurons.

[Microbiological and clinical studies of infective endocarditis due to nutritionally variant streptococci]

We report four cases of infective endocarditis due to nutritionally variant streptococci (NVS) that occurred between 1981 and 1991. Three female and one male patients had underlying heart diseases. Causative organisms showed satellitism to staphylococci. Two strains were identified as S. adjacens and the other two were identified as S. defectivus by DNA-DNA hybridization. All strains had tolerance and one strain had resistance to benzylpenicillin (MIC 4 micrograms/ml). This penicillin-resistant strain also had tolerance to gentamicin. There was no synergism of benzylpenicillin and gentamicin against this strain by a killing curve in vitro. A 11-year-old female patient with infective endocarditis due to this strain, who had a transposition of great arteries, had large vegetations in external conduits by the Rastelli's operation. Some intensive antimicrobial chemotherapies were unsuccessful and a surgical replacement of the conduits must be done in this case. Since infective endocarditis due to NVS is not rare in Japan, NVS should be considered for the causative organisms in culture negative endocarditis.

Difference in response to colony-stimulating factors and involvement of protein kinase C signal transduction system in three subclones from the ME-1 cell line and two sublines

We previously established a cell line from a patient with acute myelomonocytic leukemia with eosinophilia (M4E0), ME-1. ME-1 cells are responsive to colony-stimulating factors (CSFs) such as interleukin-3 (IL-3), IL-4, and granulocyte-macrophage CSF (GM-CSF), and exhibit monocyte-macrophage differentiation. We isolated three subclones, ME-F1 from ME-1, and ME-F2 and ME-F3 from two sublines of ME-1. These subclones had different morphologic, cytochemical, phenotypic, and cytogenetic features. They represented different monocytic-lineage differentiation stages and exhibited different responses to IL-3, GM-CSF, and especially IL-4. IL-3, GM-CSF, and IL-4 enhanced proliferation and differentiation to macrophage-like cells in the ME-F1 subclone. However, they enhanced only proliferation of ME-F2 cells and only differentiation to macrophage-like cells in the ME-F3 subclone. To elucidate possible differences in signal transduction mechanisms in ME-F1, ME-F2, and ME-F3 cells following stimulation by CSFs, we studied the effects of IL-3 and IL-4 on protein kinase C (PKC) activity. Both IL-3 and IL-4 induced a rapid, transient decrease of cytosolic PKC in ME-F1 cells, but did not affect PKC activity in ME-F2 and ME-F3 cells. The PKC inhibitors, 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine (H-7) and calphostin C inhibited IL-3-induced enhancement of proliferation and differentiation of ME-F1 cells, but did not inhibit enhancement of proliferation of ME-F2 cells and differentiation of ME-F3 cells. Our data suggest that PKC-dependent signal transduction is considerably related to IL-3-induced proliferation and differentiation of ME-F1 cells. In addition, it was demonstrated that the two subclones, ME-F2 and ME-F3, lost one of the two responses of ME-F1 cells to CSFs, either proliferation or differentiation, and simultaneously lost PKC-dependent response to CSFs.

[A case of chronic inflammatory demyelinating polyneuropathy with recurrent ophthalmoplegia, persistent conduction block, antibody activity against gangliosides GM1]

We report a 19-year-old female with chronic inflammatory demyelinating polyneuropathy (CIDP) with recurrent ophthalmoplegia. The patient had chronic, recurrent, asymmetrical, predominantly, distal limb weakness, and numbness of extremities with recurrent external ophthalmoplegia. Ophthalmoplegia developed in each attack of distal limb weakness, and also rapidly subsided with recovery of limb weakness. Motor nerve conduction studies revealed conduction block in more than one nerve and conduction velocities were generally normal in those segments of the nerve where conduction block was not detected. Serum anti-gangliosides GM1 IgM antibody investigated by ELISA was elevated. Thin-layer chromatography immunostaining also confirmed this result. Sural nerve biopsy showed normal findings. In spite of improvement of her signs and symptoms after prednisolone therapy, multifocal conduction block was persistent. Muscle power improved in association with decreased in anti-GM1 antibody activity. There were many reports of CIDP with cranial nerve involvements, but recurrent ophthalmoplegia in CIDP is rare. It is widely accepted that serum anti-GQ1b IgG antibody is associated with ophthalmoplegia in Miller Fisher syndrome and Guillain-Barré syndrome. However, serum anti-GQ1b IgG antibody was not detected in this case. It is unclear whether anti-GM1 antibody may play a role to pathogenesis of ophthalmoplegia or not in this case.

Comparison of structural proteins among antigenically different Japanese encephalitis virus strains

Based on the reactivities of monoclonal antibodies, we have reported previously that 25 Japanese encephalitis virus (JEV) strains fell into five antigenic groups: Nakayama, Beijing-1, Kamiyama, 691004 and Muar. In the present study, we compared the nucleotide and deduced amino acid sequences of the structural proteins of these strains. Four strains, Nakayama-RFVL, Beijing-1, Kamiyama and 691004, shared > 96.4% identity in the nucleotide sequence and > 94.7% identity in the amino acid sequence. However, the Muar strain had only an 80.3-87.7% homology for nucleotides and an 85.7-93.5% homology for amino acids, compared with the other four strains. The following strain-specific amino acid differences were found in the envelope protein: two in Nakayama-RFVL; three in Beijing-1; one in Kamiyama; five in 691004; 42 in Muar. These findings showed that the Muar strain was the most structurally different from the other four strains, and that it would be possible to compare antigenic differences among the JEV strains by using monoclonal antibodies which showed different specificities.