Epitope mapping and characterization of antigenic determinants of heat-stable enterotoxin (STh) of enterotoxigenic Escherichia coli by using monoclonal antibodies

A panel of monoclonal antibodies (MAbs) specific for the heat-stable enterotoxin (STh) of enterotoxigenic Escherichia coli was produced. All four MAbs (8G7, 53-4, 11C, and SH1) bound to native STh in an enzyme-linked immunosorbent assay to various degrees, with clone SH1 showing the best affinity. The MAbs were screened for neutralizing and guanylate cyclase-inhibiting activities by the suckling mouse assay and the cyclic GMP assay using T84 cells, respectively. The contact amino acid residues governing the reactivity of the four MAbs were precisely determined by using several chemically synthesized analogs of the various heat-stable enterotoxins (STa's). Three distinct antigenic sites of STh sufficiently removed from each other, one near the N terminus, another in the core functional region of the toxin, and the third in the C-terminal region, were recognized by the different MAbs. MAb SH1, which recognized Asn at position 4 and Tyr at position 5 from the N terminus was 100 times more potent in neutralizing the bioactivity of STh in the suckling mouse assay than was MAb 11C, which recognized Thr at position 16 and Tyr at position 19 from the N terminus of the STh molecule. The MAbs which recognized Leu at position 9 from the N terminus (MAb 53-4) and Tyr at position 19 from the N terminus (MAb 8G7) showed intermediate activities in the neutralization assay. The guanylate cyclase-inhibiting activities of SH1 and 11C essentially paralleled the results for the neutralization of bioactivity, while MAbs 53-4 and 8G7 exhibited reverse activity. These results indicate that MAbs that recognize the N-terminal residues which have been shown not to be essential for toxic activity have a potent protective capacity. None of the MAbs reacted with reduced and carboxy-methylated native STh. This suggests that all of the MAbs mediate their effect by reacting with conformation-dependent antigenic determinants.

Stimulation of endothelin mRNA and secretion in human endothelial cells by FK 506

FK 506 is a powerful new immunosuppressant that is more effective in preventing and treating allograft rejection than cyclosporine (CyA). This study was undertaken to examine the effect of FK 506 on stimulation of endothelin-1 (ET-1) mRNA and secretion of ET-1 in human endothelial cells (EC) compared with the effects of CyA. The dose of 0.1 microM of CyA used in clinical practice induced expression of ET-1 mRNA and increased secretion of ET-1 in EC. The same dose of FK 506 had the same effect. A clinical dose of 0.01 microM of FK 506 did not induce expression of ET-1 mRNA and did not increase the secretion of ET-1 in EC. These findings suggest that the lower incidence of complications seen with FK 506 is due in part to its use at a lower clinical dose compared with that of CyA.

Suspension organ culture of the fetal mouse ear

To observe the development of the fetal ear, we grew the explanted ears of mouse fetuses 13 days old in suspension organ culture on a roller device for 48 hours. We used the BGJb-medium (Fitton-Jackson Modification) supplemented by 25% fetal bovine serum, and added a solution containing penicillin-streptomycin at the rate of 1% to the total volume. It was observed histologically that some explants developed ossicles that corresponded with those of mouse fetuses 15 days old in vivo. Sensory structures in the inner ear developed in organ culture as well. This method may help to resolve the question of ontogenesis of the ossicles.

Surgery for cholelithiasis in cirrhotic patients

Although biliary tract surgery for cholelithiasis is performed frequently in Japan, cirrhotic patients require special consideration. Postoperative complications after biliary tract surgery were studied in 23 patients with liver cirrhosis and associated cholelithiasis, 9 of whom had no complications, 8 had minor complications, and 6 had severe complications. Concerning the relation between Child's classification and postoperative complications, no complications were seen in four Child's type A patients, but seven of ten (70%) Child's type B patients and seven of nine (78%) Child's type C patients developed complications. Two (20%) of the Child's type B patients and four (44%) of the Child's type C were severe, and three of the latter group died. Regarding the preoperative laboratory findings, significant differences were seen between the patients without complications and those with severe complications in serum bilirubin, albumin, and ICG R15 values. Of the six patients with severe complications, five had choledocholithiasis, three of whom died of liver failure, while two developed biliary peritonitis caused by insufficient fistula formation after removal of the T-tube. Thus, for the treatment of choledocholithiasis in patients with severe cirrhosis, avoiding surgical invasion through the use of such techniques as endoscopic papillotomy is recommended whenever possible.

[Development of method for measurement of pulsatile change in arterial diameter in the fetus]

The present study was designed to evaluate perfusion dynamics of organs by measuring pulsatile change in arterial diameter concomitant with flow velocity determination. An ultrasonic phased locked echo tracking system equipped with a real time linear array scanner was used to measure pulsatile change in arterial diameter. The distance from the transducer to a distal or proximal point on the inner vessel wall can be defined as the relative time difference of the zero cross for each reflective wave. The pulsatile change in the arterial diameter was a reflection of intra-arterial pressure change which was confirmed by simultaneous measurement of direct pressure in the adult brachial, femoral and descending aorta (DA) by arterial catheterization. The accuracy of measurement of arterial diameter and pulsatile change were confirmed by the coefficient of variation (C.V) in the diameter of than 4% in the former and less than 8% in the later in both inter- and intra-assay variance. In normal growth fetuses, the pulsatile changes in the DA were within the range of about 10% of the minimum arterial diameter. Intrauterine growth retarded fetuses (IUGR) who had a high pulsatility index (PI) were 7.26 +/- 0.36% (n = 5, p < 0.01 v.s. normal growth group) and showed discrete figures between pulsatile and blood flow velocity waveforms. Furthermore, large for date fetuses (LFD) who had a high PI were 12.20 +/- 0.50% (n = 3, p < 0.05 v.s. normal growth group) and had similar figures in pulsatile and blood flow velocity waveforms.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of the thermostable direct hemolysin gene (tdh) and the thermostable direct hemolysin-related hemolysin gene (trh) of Vibrio parahaemolyticus by polymerase chain reaction

Polymerase chain reaction (PCR) protocols were established for specific detection of the tdh and trh genes, the virulence marker genes of Vibrio parahaemolyticus encoding two related hemolysins. The tdh and trh genes are known to have sequence divergence of up to 3.3% and 16%, respectively. Attempts were made to find suitable primer pairs and annealing temperatures to detect each gene without fail. DNAs extracted from 36 representative strains of V. parahaemolyticus were used in the initial screening with various combinations of primer pairs and annealing temperatures. The combinations of primer pairs and annealing temperatures selected were then tested with DNAs extracted from 227 more strains of V. parahaemolyticus and from 133 bacterial strains belonging to 40 species other than V. parahaemolyticus. PCR protocols (primer pairs and annealing temperatures) were established that gave identical results to those obtained with the tdh- and trh-specific polynucleotide probes. These protocols established for the tdh and trh genes could detect 400 fg (100 cells) of cellular DNA carrying the respective gene. Spike experiments demonstrated that the sensitivities of the established PCRs were reduced by a factor of 10(4)-10(5) by an inhibitor(s) present in a normal faecal sample, indicating the need for either DNA extraction or enrichment of the faecal sample in alkaline peptone water for 4 h before the PCR of faecal samples.

Non-isotopic microtitre plate-based assay for detecting products of polymerase chain reaction amplification: application to detection of the tdh gene of Vibrio parahaemolyticus

A non-isotopic microtitre plate-based assay method was devised for detection of products of the polymerase chain reaction. This assay involves affinity immobilization of the biotinylated amplification products in microtitre plate wells and their fluorescence detection by their hybridization with an oligonucleotide probe linked to alkaline phosphatase. An advantage of this procedure is that the immobilization and hybridization are carried out simultaneously in the wells, thus shortening the assay time. The assay method was applied to the detection of the tdh gene of Vibrio parahaemolyticus. Seven copies of the target chromosome could be detected in about 45 min after 35 cycles of amplification.

[Sensitivity test for anti-tumor agents-3. MTT assay and its clinical effect]

MTT assay, a sensitivity test of anti-tumor agents was performed, and its clinical usefulness, was discussed. In 15 surgical specimens, the cell suspensions were prepared aseptically, and divided into three processing; namely, Papanicolaou (Pap) smears to confirm the malignant cells, MTT assay, and cell cultures in chamber slides. MTT assay was evaluated only when tumor cells in the chamber slide were observed 50% or more by Pap staining. Drugs judged to be effective were applied for patients, resulting in 64.2% of predictive accuracy in the sensitivity. Conclusions; 1) MTT assay was developed for sensitivity test of anti-tumor agents, 2) Strict assessment was carried out by the confirmation of cancer cells using chamber slides, 3) On clinical usefulness, predictability for the sensitivity was 64.2%, that for resistance was 100%, and over all predictability was 66.7% 4) MTT assay was useful for the determination of effective and for elimination of ineffective drugs.

[Enteroadherent Escherichia coli exhibiting localized pattern of adherence among infants with diarrhoea in Brazil--incidence and prevalence of serotypes]

The incidence of enteroadherent Escheridhia coli exhibiting localized adherence to HeLa cells was investigated using the EAF probe (Nataro et al., J. Infect. Dis., 152:560-563, 1985) among 126 infants below 3 years of age along with 126 age-matched healthy controls in Brazil. The EAF probe proved to be sensitive and specific in detection of enteroadherent E. coli. EAF-probe positive E. coli was isolated from 23.0% of the infants with acute diarrhoea while the corresponding rate of isolation from healthy controls was 11.9%. EAF-probe positive E. coli strains belonging to the classical enteropathogenic E. coli (EPEC) serogroups were more often associated with diarrheal cases (18.3%) than with strains isolated from control healthy infants (5.6%). The predominant EAF-probe positive E. coli serotypes were O55:H-, O111:H2 and O119:H6. These serotypes, especially O111:H2, were mainly isolated from cases with diarrhoea suggesting a strong causal association. Among the EAF positive non-EPEC serotypes, the most prevalent serotype was O88:H25 and this represents a, hitherto, unrecognized diarrheagenic E. coli serotype.

Detection of topoisomerase I gene point mutation in CPT-11 resistant lung cancer cell line

CPT-11, a recently developed topoisomerase I (Topo I) inhibitor, attracts the attention not only of basic researchers but also of clinicians because of its high antitumor activity. The CPT-11 resistant human lung cancer cell line, PC-7/CPT, showed 10-fold resistance compared to parental cell line, PC-7. The total activity of Topo I in the resistant cell line was one fourth that of the parental sensitive cell line. The Topo I from the resistant cells was also 5-fold more resistant to the inhibitory effect of CPT-11 than that of the parental cells. We speculated that the alteration of the Topo I gene may be responsible for the change in topoisomerase activity of the CPT-11 resistant cell line. Therefore, we analyzed the mutation of Topo I gene using the method of single strand conformation polymorphism of polymerase chain reaction and the reverse transcriptase. We divided Topo I cDNA into ten fragments which overlapped each other and covered whole coding sequences of the Topo I cDNA. We observed mobility shift of two fragments in the PC-7/CPT, suggesting the presence of some mutations in these fragments. We performed the direct-sequencing of these portions by the dideoxy chain termination method and observed an altered sequence having a G to A base change in PC-7/CPT. This base substitution results in replacement of the conserved threonine at 729 position with alanine. These results suggest that the point mutation of Topo I gene is related to the decreases of Topo I activity and the sensitivity to Topo I inhibitor in PC-7/CPT cells.

[Application of bromodeoxyuridine (BrdU) and anti-BrdU monoclonal antibody for the analysis of tumor cell kinetics by flow cytometry]

Bromodeoxyuridine (BrdU) is a thymidine analogue which is incorporated into the cells of DNA synthetic phase. BrdU-labeling index (BrdU-LI) of tumor cells can be estimated with an anti-BrdU antibody. Bivariate distributions of BrdU and DNA content are simultaneously obtained by flow cytometric two parameter analysis with a double staining method. The exact DNA synthetic cells are determined using this method by removal of the cells having S phase DNA content without DNA synthesis; quiescent (S0) cells. Once the BrdU-LIs are obtained, DNA synthesis time (Ts) and other time parameters of tumor cell kinetics can be calculated by mathematical methods. BrdU and anti-BrdU monoclonal antibody makes it possible to easily and rapidly recognize the tumor cell kinetics with high accuracy.

Gene analyses of abnormal fibrinogens with a mutation in the gamma chain

In four abnormal fibrinogens with a point mutation in the gamma chain, all characterized by impaired fibrin polymerization, we identified single base exchanges in the respective mutant gamma chain genes by polymerase chain reaction followed by DNA sequence analysis. These base exchanges accounted for the amino acid substitutions previously reported from our laboratory. They were exchanges of C to T (CGC for gamma Arg-275 to TGC for Cys) in fibrinogen Osaka II, T to G (AAT for gamma Asn-308 to AAG for Lys) in fibrinogen Kyoto I, T to C (ATG for gamma Met-310 to ACG for Thr) in fibrinogen Asahi, and G to T (GAT for gamma Asp-330 to TAT for Tyr) in fibrinogen Kyoto III. These base exchanges were found to reside in exon VIII of the gamma chain gene. Since many abnormal molecules are associated with polymerization defects, unless associated with the impaired release of fibrinopeptides A and/or B, exon VIII of the gamma chain gene may deserve careful study to define the structural alterations.

Glycoprotein receptors for a heat-stable enterotoxin (STh) produced by enterotoxigenic Escherichia coli

Glycoprotein receptors for heat-stable enterotoxin STh of enterotoxigenic Escherichia coli in the rat intestinal cell membrane were identified and characterized. Incubation of rat intestinal cell membranes with radioiodinated N-5-azidonitrobenzoyl-STh[5-19] (125I-ANB-STh[5-19]) followed by photolysis resulted in specific radiolabeling of two distinct proteins with M(r)s of 200,000 (designated STR-200A and STR-200B). STR-200A was found to be composed of two molecules of a protein with an M(r) of 70,000 (70-kDa protein), whereas STR-200B was composed of two different protein molecules with M(r)s of 53,000 (53-kDa protein) and 77,000 (77-kDa protein). These proteins showed no guanylate cyclase activity. The 70-kDa protein was labeled most with 125I-ANB-STh[5-19], suggesting that STR-200A is the main receptor protein in the rat intestinal cell membrane. The carbohydrate moieties of STR-200A and STR-200B were examined by enzymatic deglycosylation. The 70-kDa protein of STR-200A was found to contain N-linked high-mannose-type and/or hybrid-type oligosaccharides, and results suggested that it possesses at least three N glycosylation sites. The 53-kDa protein of STR-200B was found to have an N-linked complex-type oligosaccharide side chain. The deglycosylated 70-kDa protein retained activity for binding to STh, suggesting that the carbohydrate moieties of these receptor proteins are not important for binding with STh.

[Flow cytometric analysis of proliferative characteristics of human leukemic cells in bone marrows in vivo using bromodeoxyuridine (BrdU) and its monoclonal antibody]

We developed a new method for analyzing the proliferative characteristics of human acute leukemic cells in bone marrows in vivo using BrdU and its monoclonal antibody. The thirty minutes after a bolus BrdU infusion, a 1st bone marrow aspiration (BMP) was performed to calculate BrdU-LI. Then, a 150-minute continuous infusion of BrdU was started. After the infusion, a 2nd BMP was done to calculate the increasing rate of the BrdU-LI for 3 hours. Each of the bone marrow cells was analyzed by FCM. A mean value of 10.4% for BrdU-LI in 22 previously untreated patients was obtained. In 3 of the patients, Ts and Tpot ranged from 13.5 to 33.9 hours and 6.8 to 10.7 days respectively.

A new endo-beta-galactosidase acting on the Gal beta 1-3Gal linkage of the proteoglycan linkage region

A new type of endo-beta-galactosidase acting on the linkage region of peptidochondroitin sulfate was isolated from the mid-gut gland of the mollusk Patinopecten. The purification procedure included ammonium sulfate precipitation, Sephacryl S-200HR gel filtration, DEAE-Sephacel chromatography, and TSKgel Phenyl-5PW RP high performance liquid chromatography. The purified enzyme was free from exoglycosidases, sulfatases, and phosphatases. The specificity of the enzyme was as follows. 1) It acted on the internal galactoside linkage of sugar chains; 2) it specifically hydrolyzed the galactosylgalactose (Gal beta 1-3Gal) linkage, but not the galactosylxylose (Gal beta 1-4Xyl) linkage in the linkage region of peptidoglycans; 3) the enzyme activity was unaffected by the type of glycosaminoglycan, chondroitin sulfate, dermatan sulfate or heparan sulfate used as a substrate; 4) keratan sulfate and some oligosaccharides from glycolipid were not degraded by the enzyme. These properties of the endo-beta-galactosidase characterize it as a new endo-beta-galactosidase with unique specificity.

Indonesia medicinal plants. III. On the constituents of the bark of Fagara rhetza (Rutaceae). (1): Alkaloids, phenylpropanoids, and acid amide

Two new phenylpropanoids, named O-geranylsinapyl alcohol (1) and O-geranylconiferyl alcohol (2), and a new acid amide, named hazeleamide (3), were isolated from the bark of Fagara rhetza (Rutaceae), an Indonesian medicinal plant from Flores Island, Indonesia. The chemical structures of 1, 2, and 3 have been elucidated on the basis of their chemical and physicochemical properties. Among the three new compounds, hazeleamide (3) was found to show a pungent taste and to exert a moderate antimalarial activity in an in vitro test system.

Thermodynamics of Cro protein-DNA interactions

Using a highly sensitive pulsed-flow microcalorimeter, we have measured the changes in enthalpy and determined the thermodynamic parameters delta H, delta S degree, delta G degree, and delta C(p) for Cro protein-DNA association reactions. The reactions studied include sequence-nonspecific DNA association and sequence-specific DNA associations involving single- and multiple-base alterations and/or single-amino acid alteration mutants. (i) The association of Cro protein with nonspecific DNA at 15 degrees C is characterized by delta H = +4.4 kcal.mol-1 (1 cal = 4.18J), delta S degrees = 49 cal.mol-1.K-1, delta G degrees = -9.7 kcal.mol-1, and delta Cp congruent to 0; the association with specific high-affinity operator OR3 DNA is characterized by delta H = +0.8 kcal.mol-1, delta S degree = 59 cal.mol-1.K-1, delta G degree = -16.1 kcal.mol-1, and delta Cp = -360 cal.mol-1.K-1, respectively. Both nonspecific and specific Cro-DNA associations are entropy-driven. (ii) Plots of delta H vs. delta Cp and delta S degree vs. delta Cp for the 20 association reactions studied fall into two correlation groups with linear slopes of +9.4 K and -20.5 K and of -0.03 and -0.14, respectively. These regression lines have common intercepts, at the delta H and delta S degree values of nonspecific association (where delta Cp congruent to 0). The results suggest that there are, at least, two distinct conformational subclasses in specific Cro-DNA complexes, stabilized by different combinations of enthalpic and entropic contributions. The delta G degree and delta Cp values form an approximately single linear correlation group as a consequence of compensatory contributions from delta H and delta S degree to delta G degree and to delta Cp. Cro protein-DNA associations share some similar thermodynamic properties with protein folding, but their overall energetics are quite different. Although the nonspecific complex is stabilized predominantly by electrostatic forces, it appears that H bonds, van der Waals contacts, hydrophobic effects, and charge interactions all contribute to the stability (delta G degree and delta Cp) of the specific complex. (iii) The variations in the values of the thermodynamic parameters are in general accord with our knowledge of the structure of the Cro-DNA complex.