Bicarbonate buffer dissolution test with gentle mechanistic stress for bioequivalence prediction of enteric-coated pellet formulations

This study aimed to develop a dissolution test that can predict the bioequivalence (BE) of enteric-coated pellet formulations. The original duloxetine hydrochloride capsule (reference formulation (RF); Cymbalta® 30 mg capsule) and four generic test formulations (two capsules (CP) and two orally disintegrating tablets (OD)) were used as model formulations. Clinical BE studies were conducted on 24-47 healthy male subjects under fasting conditions. Dissolution tests were performed using a compendial paddle method (PD) (paddle speed: 50 rpm) and a flow-through cell method (FTC) (flow rate: 4 mL/min). For a further test, cotton balls were added to the vessel to apply gentle mechanistic stress to the formulations, and paddle speed was reduced to 10 rpm (paddle with cotton ball method (PDCB)).All the dissolution tests were conducted with 0.01 M HCl (pH 2.0) for 0.5 h followed by 10 mM bicarbonate buffer solutions (pH 6.5) for 4 h. One each of the two CP and two OD showed BE with RF. PDCB was able to discriminate between BE and non-BE formulations, while this was not possible with PD and FTC. In PDCB, the cotton balls intermittently moved the pellets near the vessel bottom. PDCB is useful for predicting BE during formulation development.

Development of bicarbonate buffer flow-through cell dissolution test and its application in prediction of in vivo performance of colon targeting tablets

The purpose of this study was to develop a bicarbonate buffer flow-through cell (FTC) dissolution test. Mesalazine colon targeting tablets of a generic development product (test formulation, TF; Mesalazine 400 mg tablet) and the original product (reference formulation, RF; Asacol® 400 mg tablet) were used as model formulations. A clinical bioequivalence (BE) study was conducted on 48 healthy male subjects under fasting conditions. The oral absorption time profiles were calculated by point-area deconvolution. The compendial paddle and FTC apparatus were used for dissolution tests. Bicarbonate or phosphate-citrate buffer solutions (McIlvaine buffer) were used as the dissolution media. A floating lid was used to maintain the pH value of the bicarbonate buffer solution in the vessel (paddle) or the reservoir (FTC). In the development of bicarbonate FTC method, the pH changes of bicarbonate buffer solution (pH 5.5-7.5; 5-50 mM bicarbonate) were evaluated. For the evaluation of colon targeting tablets, the dissolution profiles of TF and RF were measured at a pH of 7.5. The TF and RF formulations were exposed to 0.01 HCl (pH 2.0) for 2 h before pH 7.5. In the clinical BE study, drug dissolution started 4-8 h after oral administration and continued slowly more than 10 h. Both the area under the curve (AUC) and maximum plasma concentration (Cmax) of TF were approximately twice as high as those of RF. In the development of the bicarbonate FTC method, the pH change of the bicarbonate buffer solution was suppressed by the floating lid within ∆pH < 0.1 over 10 h. In the dissolution test of McIlvaine buffer solutions, TF and RF showed faster disintegration and higher dissolution than those observed in the clinical BE study. When using the paddle apparatus the dissolution profiles of TF and RF in both buffer solutions were not consistent with those of the clinical result. In bicarbonate FTC, the disintegration time, dissolution rate, and dissolution inequivalence between TF and RF were consistent with the results of the clinical BE study. In conclusion, the bicarbonate FTC method was constructed for the first time in this study. This method is simple and practically useful for predicting in vivo performance of colon targeting tablets during drug development.

P14.01 Differential diagnosis of IDH mutant/IDH wildtype of glioma by using 11C-methionine, 11C-choline, and18F-fluorodeoxyglucose positron emission tomography

BACKGROUND

Positron emission tomography (PET) is important in noninvasive diagnostic imaging of gliomas. There are many PET studies on glioma diagnosis based on the 2007 World Health Organization (WHO) classification; however, there are no studies on glioma diagnosis using the new classification (the 2016 WHO classification).Here we investigated the relationship between PET imaging using 11C-methionine (MET), 11C-choline (CHO), and 18F-fluorodeoxyglucose (FDG) and wildtype isocitrate dehydrogenase (IDH) (IDH-wt)/mutant IDH (IDH-mut) in astrocytic and oligodendroglial tumors according to the 2016 WHO classification.

MATERIAL AND METHODS

In total, 105 patients with newly diagnosed cerebral gliomas (six diffuse astrocytomas [DAs] with IDH-wt, six DAs with IDH-mut, seven anaplastic astrocytomas [AAs] with IDH-wt, 24 AAs with IDH-mut, 26 glioblastomas [GBMs] with IDH-wt, five GBMs with IDH-mut, 19 oligodendrogliomas [ODs], and 12 anaplastic oligodendrogliomas [AOs]) were included. All OD and AO patients had both IDH-mut and 1p/19q codeletion. The maximum standardized uptake values (SUVs) of the tumor/normal cortex mean SUV ratios (T/N ratios) for MET, CHO, and FDG were calculated; the mean T/N ratios of DA, AA, and GBM with IDH-wt/IDH-mut were compared. The diagnostic accuracy for distinguishing gliomas with IDH-wt from those with IDH-mut was assessed using receiver operating characteristic (ROC) curve analysis of the mean T/N ratios for the three PET tracers.

RESULTS

There were significant differences in the mean T/N ratios for all three PET tracers between the IDH-wt and IDH-mut groups including all histological classifications (p<0.001). Among the 27 gliomas with mean T/N ratios higher than the cutoff values for all three PET tracers, 23 (85.2%) were classified into the IDH-wt group using ROC analysis. In DA, there were no significant differences in the T/N ratios for MET, CHO, and FDG between the IDH-wt and IDH-mut groups. In AA, the mean T/N ratios of all three PET tracers in the IDH-wt group were significantly higher than those in the IDH-mut group (p<0.001). In GBM, the mean T/N ratio in the IDH-wt group was significantly higher than that of the IDH-mut group for both MET (p=0.034) and CHO (p=0.01). However, there was no significant difference in the ratio for FDG.

CONCLUSIONS

PET imaging using MET, CHO, and FDG was confirmed to be informative for preoperatively differentiating gliomas according to the 2016 WHO classification, particularly for differentiating IDH-wt and IDH-mut tumors.

Albumin fusion of thioredoxin--the production and evaluation of its biological activity for potential therapeutic applications

Thioredoxin-1 (Trx) is a redox-active protein with anti-inflammatory effects. The effect of albumin fusion on the pharmacokinetic and pharmacodynamic properties of Trx was evaluated in this study. The findings indicate that the properties of human serum albumin and the fusion protein are comparable. The fusion protein showed similar plasma concentration and organ distribution profiles as human serum albumin. The fusion protein accumulated in lungs, reaching levels higher than Trx. In an insulin reducing assay, the activity of the fusion protein was 60% of the activity of Trx. However, survival rate of endotoxic shock mice induced by the administration of a lipopolysaccharide and D-galactosamine for fusion protein was double that of Trx. The findings reported herein indicate that the fusion protein is likely to have great clinical applications in areas such as the treatment of reperfusion injuries.

Vertical antiresonant reflecting optical waveguide coupler for three-dimensional optical interconnects: optimum design for large tolerance, high coupling efficiency, and short coupling length

A compact antiresonant-reflecting-optical-waveguide-(ARROW-) type vertical coupler for three-dimensional optical interconnects was demonstrated. The coupler consists of stacked ARROW's channeled by the stripe lateral confinement structure, and each waveguide is completely separated by a thin metal film in the separation region. In the coupling region the intermediate cladding of a previous coupler was made of the same material as that of the first cladding or the core. However, we had to overcome the problem that both the high coupling efficiency and the large fabrication tolerance cannot be achieved simultaneously. Thus we incorporated an intermediate cladding made of a material different from that of the core and the first cladding. The refractive index and the thickness of the intermediate cladding were optimally designed to achieve large fabrication tolerance and a short coupling length with a high coupling efficiency. The coupling length was reduced from 4.1 to 0.8 mm, and a high coupling efficiency of 96% was experimentally demonstrated.

Hepatic infarction with portal thrombosis

A case of hepatic infarction with portal thrombosis is reported. A 63-year-old woman with liver cirrhosis and esophageal varices was admitted for treatment of the esophageal varices. Endoscopic variceal ligation (EVL) and endoscopic injection sclerotherapy (EIS) were performed. Two months later, she experienced right hypochondralgia and right flank pain. Serum transaminase levels were suddenly elevated, and computed tomography scans of the liver showed multiple small nodular lesions. Her condition worsened, and she died of hepatic failure. Autopsy revealed splenic and portal vein thrombosis, multiple hepatic infarction, and evidence of chronic pancreatitis. We believe that liver cirrhosis and chronic pancreatitis were the main risk factors for the portal thrombosis, and the treatment for esophageal varices appeared to have triggered the thrombosis. The hepatic infarction was caused by the portal thrombosis.

Expression of cytoskeletal-associated protein tyrosine phosphatase PTPH1 mRNA in human hepatocellular carcinoma

We investigated the mRNA expression of cytosolic protein tyrosine phosphatase (PTPH1), which has a homologous domain to cytoskeletal-associated proteins, in human hepatocellular carcinomas (HCCs) by using reverse transcriptase-polymerase chain reaction (RT-PCR). PTPH1 mRNA was detected in all HCC cell lines (n = 6), and HCC and adjacent noncancerous tissues (n = 8) examined, indicating that PTPH1 was expressed in HCCs and hepatocytes. There was no remarkable difference in the level expression of PTPH1 mRNA between HCC and adjacent noncancerous tissues. We also performed RT-PCR single-strand conformation polymorphism (SSCP) analysis in HCC cell lines and tissues in the C-terminal region of the catalytic domain of PTPH1. In the cHc4 cell line and a HCC tissue specimen, a shifted band was detected, although it was not found in the non-cancerous tissue of the HCC specimen. Nucleotide sequence analysis showed a common mutation from T to C at the third letter of codon 919 which did not lead to amino acid substitution. These results suggest that another mutation leading to the development of HCC could occur in some region of PTPH1 other than that investigated in this study.

Prevalence of HBV and HCV infection in Japanese patients with hepatocellular carcinoma

The prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection was investigated in 63 Japanese patients with hepatocellular carcinoma (HCC). HBV infection was confirmed by measuring hepatitis B surface antigen and HBV-DNA in the serum, and HCV infection was confirmed by measuring antibody to HCV using a 2nd generation test and HCV-RNA in serum. Some 54.0% of the patients had HCV infection only, 27.0% had HBV infection only, and 9.5% had both HCV and HBV infection. Only 9.5% of HCC patients had neither HCV nor HBV markers. These results indicate that, in Japan, HCV and HBV infection is an important factor associated with HCC, and that the hepatitis virus may have a role in the carcinogenesis of HCC.

Expression and chromosomal assignment of PTPH1 gene encoding a cytosolic protein tyrosine phosphatase homologous to cytoskeletal-associated proteins

We have investigated the mRNA expression of 2 human protein tyrosine phosphatases with sequence homology to cytoskeletal proteins, PTPH1 and PTPMEG. Northern-blot analysis of PTPH1 using poly (A)+ RNA from normal human colon tissue showed a low-abundance message of 4.3 kb. Reverse-transcriptase/polymerase-chain reaction (RT-PCR) was therefore used to detect it in a wide variety of cell lines including 9 colorectal, 5 gastric, 5 hepatic and 6 hematopoietic tumor cells. PTPH1 mRNA was not detected only in Colo 320 cells over-expressing c-myc mRNA, among the colorectal cancer cell lines examined. When Colo 320 cells were incubated with 5 mM sodium butyrate for 5 days, PTPH1 mRNA became detectable, concomitant with the marked decrease in the expression level of c-myc mRNA. Moreover, the chromosomal localization of PTPH1 gene was investigated by fluorescence in situ hybridization. Interestingly, PTPH1 gene was mapped to 9q31 where the gene for Gorlin syndrome, a putative tumor suppressor gene, exists.

Human endothelial cells: effect of TNF-alpha on peripheral blood mononuclear cell adhesion

Human umbilical vein endothelial cells (HUVEC) were cultured and treated for varying periods with a range of concentrations of tumour necrosis factor-alpha (TNF-alpha). After this treatment the proportion of peripheral blood mononuclear cells (PBMC), previously depleted of plastic adherent cells, capable of binding to the endothelial cells was assessed. Few PBMC bound to HUVEC which had not been pretreated with TNF-alpha but up to 36% bound after pretreatment of the endothelial cells with TNF-alpha for 10 hr at a concentration of 10 U/ml. Phenotypic characterization of the adherent and non-adherent PBMC subpopulations revealed that natural killer (NK) cells (CD16+) and a proportion of memory helper T cells (CD4+ CD45RA-) bound to TNF-alpha pretreated HUVEC but that few naive helper T cells (CD4+ CD45RA+) showed similar binding. Cytotoxicity assays for NK activity were used to analyse functionally the adherent and non-adherent PBMC subpopulations. It was found that the cell subpopulation which did not adhere to TNF-alpha pretreated HUVEC mediated little lysis of K562 target cells. Conversely, the endothelial cell-adherent PBMC subpopulation produced active lysis supporting the phenotypic evidence that NK cells were concentrated within this subpopulation. These results suggest that TNF-alpha has a rapid and profound up-regulatory effect on the expression of adhesion molecules on the surface of HUVEC. Furthermore, it is apparent that these up-regulated adhesion molecules preferentially bind NK cells and a subset of memory helper T cells from the PBMC population.

Synthesis and assignment of novel [125I]-labeled 1 alpha,25-dihydroxyvitamin D3 derivatives

This paper describes the synthesis and structural assignment of noval 125I-1 alpha,25-dihydroxyvitamin D3 derivatives (1a) and (1b) labeled with 125I-Bolton-Hunter reagent [N-succinimidyl 3-(4-hydroxy-3-iodo[125I]phenyl)propionate] (1), which is known as a protein-labeling reagent, as tracers for radioimmunoassay (RIA). The radiospecific activities of these tracers (1a) and (1b) were calculated as 2,200 Ci/mmol (81.4 TBq/mmol).

Renal allograft rejection: investigation of alloantigen presentation by cultured human renal epithelial cells

Defined lines of primary human renal epithelial cells were established and their expression of class II major histocompatibility (MHC) antigens was up-regulated by culture with interferon-gamma (IFN-gamma). The ability of these cells to stimulate the proliferation of allogeneic peripheral blood mononuclear cells (PBMC) was compared with that of endothelial cells and splenic mononuclear cells. It was found that both endothelial and splenic cells stimulated lympho-proliferation but that cultured renal epithelial cells were non-stimulatory. The failure of proliferation by allogeneic lymphocytes in culture with epithelial cells was not overcome by treatment with interleukin-1 (IL-1) or indomethacin. However, addition of IL-2 to mixed cultures of allogeneic PBMC and renal epithelial cells stimulated lympho-proliferation and allowed the generation of lymphoid cell lines which mediated non-specific lysis of renal epithelial cell lines. Stimulation of PBMC by mixed lymphocyte culture yielded an allospecific T-cell line which was added either to renal epithelial cells from the same donor as the stimulator cells used in the priming reaction or from a third-party donor; lympho-proliferation was observed in the specific secondary reaction but not in the non-specific reaction. These findings indicate that class II MHC antigen-expressing epithelial cells within a renal allograft may not initially stimulate the proliferation of resting allospecific recipient lymphocytes. However, within a rejecting graft it is likely that high local concentrations of IL-2 are present and that many of the infiltrating allospecific lymphocytes will be primed by previous contact with donor antigen-presenting cells, such as vascular endothelial cells or dendritic cells. Therefore, expression of class II MHC antigens by epithelial cells within the microenvironment of a renal allograft may render such cells immunogenic and able to play a direct role in the lymphocyte-mediated intragraft rejection process.

Synthesis and characterization of oligodeoxynucleotides containing the mutagenic base analogue 4-O-ethylthymine

A method for the preparation of oligonucleotides containing the mutagenic base 4-O-ethylthymine is described for the first time. Use of p-nitrophenylethyl type base protecting groups together with phosphitetriester solid-phase methodology makes possible the rapid and efficient preparation of oligonucleotides bearing 4-O-ethylthymine, while standard base protecting groups are not compatible with the presence of this base. Possible applications of this methodology are discussed.

Membrane elasticity of mouse dorsal root ganglion neurons decreases with aging

Elastic area compressibility modulus (EACM) method was applied to measure the membrane elasticity of cultured dorsal root ganglion neurons from fetal and 3-month-old mice. The values of the EACM were 21.3 dyn/cm in 3-month-old neurons and 2.8 dyn/cm in fetal neurons. These results indicate that neural cell membrane elasticity decreases with aging.

[The effect of ammonium fluoride solution at various concentrations on enamel]

The fluoride concentrations of ammonium fluoride solution (NH4F,pH 4.4), which has the same effect on enamel powder as conventional APF solution, were studied. Human enamel powder (200 mesh passed) was treated with solutions of NH4F (1,000 ppmF-, 3,000 ppmF-, 5,000 ppmF-, 7,000 ppmF-, 9,000 ppmF-, pH 4.4) and APF (9,000 ppmF-, pH 3.4) for 5 min. at 37 degrees C. Some of the specimen was washed with 1MKOH solution for 48 hours. Fluoride uptake by enamel powder was analyzed by means of chemical analysis and reaction products identified using X-ray diffractometry. The fluoride uptake of 5,000 ppmF- of NH4F-treated enamel was the same as that of APF-treated enamel. X-ray diffractometry showed that CaF2 was formed in the experimental groups. CaF2 with high crystallinity was formed in the NH4F-treated enamel, and the peak height of X-ray diffraction pattern of CaF2 in 3,000 ppmF- of NH4F-treated enamel was the same as that of APF-treated enamel. In conclusion, the ammonium fluoride solution of 3,000-5,000 ppmF- had a similar effect on enamel powder as conventional APF solution.

An autopsy case of intramedullary venous malformation of the spinal cord with spreading hematomyelia

A 23-year-old Japanese woman experienced sudden severe shoulder pain, and subsequently died of cardiorespiratory arrest after an 8-day course of illness. Autopsy revealed a venous malformation in the spinal cord at the C6 level with fresh massive hemorrhage showing widespread rostrocaudal extension. The upper limit of the hemorrhage was in the left gracile nucleus of the medulla oblongata, and the lower limit was in the left posterior horn of the spinal cord at L4. The hemorrhage extended through the spinal cord, involving the left posterior horn and intermediate zone of the gray matter and the ventral part of the posterior funiculus. The mechanism of the extension of the hemorrhage and the pathogenesis of the spinal venous malformation are discussed.

Endoscopic laser coagulation through an optical laser balloon

An endoscope was equipped with a saline-filled latex rubber balloon at its tip to displace contaminating blood, bile, or gastric contents during operative portoscopy, biliary endoscopy, or upper gastrointestinal endoscopy. A fiber with its tip inside the balloon transmitted energy from an Nd:YAG laser for coagulation of tumors in one bile duct cancer, in six portal vein growths from primary liver cancers, and in a superficially growing stomach cancer. The balloon increased the precision of irradiation by making lesions easier to identify through displacement of bile or blood and by keeping the fiber tip at a fixed position relative to the lesion. The technique, basic experimental studies, and clinical experiences are reported.

Interactions of water-soluble porphyrins with hexadeoxyribonucleotides: resonance raman, UV-visible and 1H NMR studies

The interactions of the water-soluble porphyrins M(TMpy-P4) [M = H2, Cu(II), Ni(II), and Co(III); TMpy-P4 = tetrakis(4-N-methylpyridyl)porphyrinato ion], with the hexadeoxyribonucleotides d(CGTACG)2, d(TACGTA)2, d(GCATGC)2, d(TGTGCA)2, and d(CTATAG)2 have been investigated by resonance Raman and/or UV-visible spectroscopy. The results indicate that all hexamers containing the 5'CG3' as well as the 5'GC3' site, and also the mismatched hexamer d(TGTGCA)2, are capable of intercalating the H2, Cu(II) and Ni(II) porphyrins. 1H nuclear magnetic resonance spectra of d(CGTACG)2 mixed with Cu(TMpy-P4) have provided further evidence for the intercalation. For the other cases, outside binding by localized electrostatic interaction is suggested. There is no evidence of groove binding to any of the hexamers. Possible reasons for different binding properties of long and short helices are discussed.

Conformation and dynamics of Z-DNA oligomer duplex of d[(CG)3TATA(CG)3] in solution

The conformation and dynamics of a DNA oligomer, d[(CG)3TATA(CG)3], in 4M NaClO4 (Z-TATA 16 mer) have been studied by 1H NMR. The principal results of our investigation are: (i) at low temperature d[(CG)3TATA(CG)3] exists as duplexes in both low (0.1M NaCl) and high (4M NaClO4) ionic strength solutions; (ii) CGCGCG segments undergo the B-to-Z transition in 4M NaClO4; (iii) even in 4M NaClO4 the TATA box exhibits non-Z-structures and possesses multiple conformations which are slowly exchanging on the NMR chemical shift difference time scale; and, (iv) the Z-type structure of the CGCGCG segments induced in 4M NaClO4 is more conformationally mobile than its B-type counterpart in 0.1M NaCl on the nanosecond time scale.

Conformation and dynamics of a left-handed Z-DNA hairpin: studies of d(CGCGCGTTTTCGCGCG) in solution

The physical properties of the DNA oligomer d(CGCGCGTTTTCGCGCG) in solvents containing 4 M NaClO4 and 0.1 M NaCl were investigated by proton NMR, optical melting, and circular dichroism spectroscopy. Results of these investigations are as follows: (i) The DNA hexadecamer exists as a unimolecular hairpin in either high or low salt. (ii) In high salt the stem region of the hairpin is in the left-handed Z conformation. (iii) In either high or low salt, the duplex stem of the hairpin is stabilized against melting by approximately 40 degrees C compared to the linear core duplex. The added stability of the hairpin is entropic in origin. (iv) In high salt, as the temperature is elevated, the equilibrium structure of the duplex stem of the hairpin shifts from the Z to the B conformation before melting. (v) In low salt, when the DNA duplex exists in the B conformation, attachment of a T4 single-strand loop to one end only slightly decreases (by 14%) the correlation time of the CH5-CH6 interproton vector. In high salt, when the DNA duplex exists in the Z conformation, the correlation time of the CH5-CH6 interproton vector decreases by 51%. Since these viscosity-corrected correlation times are taken to be indicators of duplex motions on the nanosecond time scale, this result directly suggests a larger amplitude of these motions is present in the duplex stem of the hairpin when it exists in the Z conformation.

Adaptation of cultured mammalian neurons to a hypotonic environment with age-related response

The response of neurons to osmolal concentration changes has not been well-documented compared to erythrocytes, urinary bladder and epithelial cells. The effects of a hypotonic solution on morphology and electrophysiological functions in cultured dissociated neurons can be precisely studied. From the analysis of video pictures from Nomarski optics, diameters of the cells were seen to increase and then recover to the initial values after the application of a hypotonic solution. The rate of increase of cell size in fetal neurons was 4-5 times faster than in mature neurons. This age-related transient response was accompanied by a change of resting potential and membrane resistance. This transient depolarization and decrease of the resistance corresponded to morphological changes. However, the amplitude of an action potential scarcely changed during the cell membrane expansion. It is plausible that increased membrane tension caused by the membrane expansion might facilitate the opening of the channel. The cell membrane expansion might also increase ionic permeability through the membrane. This may reduce a swollen cell volume to the initial one by diluting their intracellular solute concentration. After this adaptation the cultured neurons were able to survive for a long time and extend processes in the hypotonic environment.

X-ray structure of a DNA hairpin molecule

We have solved the crystal structure of a synthetic DNA hexadecanucleotide of sequence: C-G-C-G-C-G-T-T-T-T-C-G-C-G-C-G, at 2.1 A resolution, and observed that it adopts a monomeric hairpin configuration with a Z-DNA hexamer stem. In the T4 loop the bases stack with one another and with neighbouring molecules of the crystal, and not with base pairs of their own hexamer stem. Two thymine T10 rings from different molecules stack between the C1-G16 ends of a third and a fourth hairpin helix, in a manner that suggests T-T base 'pairing' and simulates a long, 13-base-pair helix. Although such T-T interactions would not be present in solution, they illustrate a remarkable tendency of thymines for self-association. Purine-purine G-A base pairs are known to exist in the anti-anti conformation with an increase in local helix width; it may be that more serious consideration should be given to the possible existence of pyrimidine-pyrimidine C-T base pairs with decreased local helix width, particularly where several such base pairs occur sequentially.

A case of early cancer in the gallbladder: immunohistological analysis with monoclonal antibodies

A case of early cancer in the gallbladder is reported. The tumor was disclosed as an echogenic nodular lesion with irregular margin by ultrasonography and endoscopic retrograde cholangiography. Among several tumor markers, CA19-9 showed a slightly higher level (51 U/ml). An operation was carried out because of the tumor size (over 10 mm) and the coexistence of a gallstone. The tumor was a well differentiated tubular adenocarcinoma. In the carcinoma tissue, CA19-9 and YH206 antigens showed different staining patterns, the latter antigen being detected by the monoclonal antibody, YH206, established in our laboratory. Although CA19-9 was strongly positive in the non-cancerous gallbladder epithelial cells, the YH206 antigen was negative. A slight elevation of the CA19-9 level in the patient's serum was probably caused by a diffusion of the CA19-9 antigen from the gallbladder epithelial cells to the serum, due to inflammation. On the other hand, it is interesting to note that the YH206 antigen was not demonstrated in the non-cancerous gallbladder epithelial cells but was in the cancer tissue.

NMR studies of the stable mismatch purine-thymine in the self-complementary d(CGPuAATTTCG) duplex in solution

One- and two-dimensional nuclear Overhauser effect experiments demonstrate that a single hydrogen bond between a T imino proton and purine N3 is sufficient to hold the base pair dPu.dT in d(CGPuAATTTCG) by a Watson-Crick fashion rather than a Hoogsteen type. In addition, the dPu.dT base pair is well stacked with neighboring base pairs. The spin-lattice relaxation measurements at 30 and 35 degrees C of two decamers, d(CGPuAATTTCG) and d(CGAAATTTCG), reveal that the elimination of two single hydrogen bonds of dA.dT base pairs (due to the substitution of adenine for purine) in the sequence results in an increase in the overall imino proton exchange rate from 7 to 36 s-1 at the site of mismatch.

Dissociation kinetics of 19 base paired oligonucleotide-DNA duplexes containing different single mismatched base pairs

The dissociation kinetics of 19 base paired oligonucleotide-DNA duplex containing a various single mismatched base pair are studied on dried agarose gels. The kinetics of the dissociation are first order under our experimental conditions. The incorporation of a single mismatched base pair destabilizes the DNA duplexes to some extent, the amount depending on the nature of the mismatched base pair. G-T and G-A mismatches slightly destabilize a duplex, while A-A, T-T, C-T and C-A mismatches significantly destabilize it. The activation energy for the overall dissociation processes for these oligonucleotide-DNA duplexes containing 19 base pairs is 52 +/- 2 Kcal mol-1 as determined from the slope of Arrhenius plot.