Prediction of the early prognosis of the hepatectomized patient with hepatocellular carcinoma with a neural network

The early prognosis of the hepatectomized patients with hepatocellular carcinoma was determined preoperatively with a perceptron-type neural network. The neural network was trained with the preoperative data of 54 example cases with the early prognosis, successful or died of hepatic dysfunction, as teaching signals. After learning these examples, the neural network came to give a precise prediction to the example data except for one case. With the learned neural network, the outcomes of the hepatectomy of 11 patients (10 successful; 1 died) were predicted prospectively with 100% precision. The usefulness of the neural network for the prediction was determined.

In vitro mutagenesis of growth hormone receptor Asn-linked glycosylation sites

Site-directed mutagenesis was used to replace asparagine (Asn) residues with glutamine (Gln) at the five potential N-linked glycosylation sites located at positions 28, 97, 138, 143, and 182 in the extracellular domain of the porcine growth hormone receptor (pGHR). These mutated pGHR cDNAs were stably expressed in mouse L cells. Single substitution of the Asn residues did not alter growth hormone binding when compared to cells which express native pGHR (KD approximately 1 nM). However, substitution of the five potential Asn-linked sites together (pGHR delta 5) resulted in a 20-fold reduced GH binding affinity (KD = 20 nM). Residues Asn97, Asn138, and Asn182 were apparently glycosylated and upon cross-linking with 125I-labeled pGH migrated as a molecular complex of approximately 130 kDa. Native pGHR and pGHR analogs with substitutions of N28Q and N143Q when cross-linked to 125I-labeled pGH, migrated with a Mr of 138 kDa. The fully deglycosylated cross-linked receptor, pGHR delta 5, migrated as a complex of 108 kDa. Therefore, each carbohydrate moiety contributed approximately 10 kDa to the total molecular mass of the pGHR, in sum contributing 30 kDa to the total Mr of the glycosylated pGHR. pGHR delta 5 was able to internalize nearly all the bound 125I-labeled pGH within 10 min, whereas native pGHR and individual Asn substituted pGHR analogs internalized 25% of bound 125I-labeled pGH at 10 min. Also, mutagenesis of the pGHR five potential Asn-linked glycosylation sites, either singly or together, did not alter the ability of GH to induce tyrosine phosphorylation of a 95-kDa protein. Together, the results indicate that three of the five pGHR Asn residues are apparently glycosylated and are necessary for maintenance of a high affinity GH binding site and for GH internalization. However, glycosylation of the pGHR is not critical for eliciting tyrosine phosphorylated proteins following the GH/GHR interaction.

Induction of free radicals and tumors in the kidneys of Wistar rats by ferric ethylenediamine-N,N'-diacetate

An iron chelate, ferric ethylenediamine-N,N'-diacetate [Fe(III)-EDDA], was found to produce hydroxyl radicals with hydrogen peroxide, as determined by both a deoxyribose degradation test and electron spin resonance. Hydroxyl radical production was inhibited not only by adding hydroxyl radical scavengers and catalase, but also by adding superoxide dismutase to the reaction mixture, suggesting that superoxide anion may be involved in the hydroxyl radical production. A single injection of Fe(III)-EDDA (10 mg Fe/kg body wt) to Wistar rats induced thiobarbituric acid reactivity in the kidneys and liver. Repeated injections of Fe(III)-EDDA (10 mg Fe/kg body wt, twice weekly for 3 months) induced a 40% incidence of renal tumors, including renal adenocarcinoma and renal adenoma, 1 year later. These results suggest that Fe(III)-EDDA is an effective free radical producer in vitro and in vivo and that it may be useful in preparing animal models related to iron-dependent free radical damage. The results support our hypothesis that endogenous or exogenous iron, complexed with certain kinds of chelators, promotes free radical-dependent tissue damage and ultimately leads to carcinogenesis in the affected tissue.

Superinfection of cats with feline immunodeficiency virus subtypes A and B

The ability of feline immunodeficiency virus (FIV) isolates from subtypes A and B to superinfect cats and cell cultures was tested. Three specific pathogen-free (SPF) cats were first inoculated with 10 ID50 of subtype B virus (FIVBang) and 30 weeks later inoculated with 100 ID50 of subtype A virus (FIVPet). On the basis of subtype-specific PCR analysis, both FIV subtypes were detected in the peripheral blood lymphocytes (PBLs) of two of three cats from 9 to 30 weeks following the second inoculation. Only the first virus was detected in the bone marrow (BM) cells of these two cats until 30 weeks following the second inoculation, at which time the second virus was finally detected in their BM cells. Both cats developed significant virus-neutralizing (VN) antibodies to the second virus by 15 weeks following the second inoculation; but only one cat had high VN titers to the first virus, which remained at the same level even after the second inoculation. The two control cats inoculated with only the second virus developed VN titers specifically to the second virus and were consistently PCR positive for the virus in PBLs and BM cells starting 9 weeks postinoculation. Thus a delay in BM infection with the second virus was observed in the two superinfected cats. In contrast, one of three cats had neither VN antibodies to the second virus nor PCR signal of the second virus in its PBLs, BM, and lymph node throughout the 30 weeks of study and it appeared to be resistant to superinfection.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of pontine hematoma with Foville's syndrome in childhood]

We reported a surviving case of 6-year-old boy with pontine hematoma. He complained of headache as an initial symptom and developed progressively Foville's syndrome with impairments of the IX-XII cranial nerves. Although brainstem tumor was suspected initially using CT scan, MRI revealed the existence of hematoma in the ventromedial pons. During the first 4 months of his clinical course, Gd-DTPA did not demonstrate any enhancement in that lesion. However, hemangiomatous lesion was suspected by subsequent serial MRIs with positive Gd-DTPA enhancement. Using conservative treatment including oral corticosteroids, all the neurological deficits disappeared in several months and he did not show any recurrence of clinical signs for 3 years. It was suggested that MRI was very useful in the differential diagnosis and the follow-up of hematoma in the posterior fossa.

Effect of an anxiolytic on lipid profile in non-insulin-dependent diabetes mellitus

The effects on serum lipid levels of reducing stress were examined in 20 patients with non-insulin-dependent diabetes mellitus. An anxiolytic, fludiazepam, was administered to the patients for 12 weeks and their lipid profiles and State-Trait Anxiety Inventory scores at the beginning and end of treatment were compared. The high-density lipoprotein cholesterol level increased significantly after the administration of anxiolytic, but other aspects of the lipid profile were unchanged. Both trait and state anxiety scores decreased significantly with the administration of anxiolytic. The results indicate that improvement of stress in patients with non-insulin-dependent diabetes mellitus increases high-density lipoprotein levels.

Basic study on hepatic resection under partial perfusion cooling

To improve liver quality after reperfusion following partial hepatectomy under total or partial cooling of the liver (HPC), a new perfusion solution containing 100 mM L-histidine (KM solution) was developed. The livers of Lewis rats were removed and perfused for 2 hours at 20 degrees C with lactated Ringer's (LR) solution (group A) or the KM solution (group B). They were reperfused with rat blood at 37 degrees C at a perfusion pressure of 5 cmH2O while monitoring the portal and peripheral tissue blood flows. At the end of reperfusion, bile production, lactate dehydrogenase (LDH) secretion, and tissue adenosine triphosphate (ATP) was measured. Recovery of portal and peripheral tissue blood flows of the group B livers after reperfusion were significantly better than those of group A. Viability of the group B livers, assessed by bile production, tissue ATP value, and LDH release, was preserved better than that of group A livers. In situ total liver perfusion with LR (group C) and KM (group D) solutions for 1 hour at 20 degrees C followed by partial hepatectomy of the left lateral lobe was performed. The 1-week survivals of the group C and D rats were 25% and 100%, respectively (p < 0.05). It was concluded that KM solution is suitable for HPC.

Two-dimensional demonstration of myenteric nerve plexus: application for pseudo-Hirschsprung's disease

The use of two-dimensional demonstration of myenteric nerve plexus for the morphological estimation of pseudo-Hirschsprung's disease is introduced. By fluorescent immunohistochemistry for S-100 protein on flat-mounted frozen sections, a decrease in the amount of ganglionic plexuses in the small intestinal segments in cases of pseudo-Hirschsprung's disease was able to be distinguished from normoganglionic plexuses in control cases. Moreover, a morphological difference between the two types of cases was clearly demonstrated. This method may be an indispensable tool in the reliable diagnosis of pseudo-Hirschsprung's disease.

A phase II study of cisplatin in patients with biliary tract carcinoma

A phase II study of cisplatin was performed in 13 previously untreated patients with unresectable biliary tract carcinoma. The drug was given intravenously at a dose of 80 mg/m2/day once every 4 weeks. Of 13 patients evaluated, 1 showed partial response lasting 3 months, while no patients showed complete response. Of 9 patients, whose serum level of carcinoembryonic antigen (CEA) was high (> or = 10 ng/ml) before treatment, 4 showed > or = 50% reduction in serum CEA level after treatment. The current study indicates that cisplatin does not have significant antitumor activity against biliary tract carcinoma.

Diagnosis of pelvic endometriosis by magnetic resonance imaging using "fat-saturation" technique

OBJECTIVE

To assess the usefulness of fat-saturated magnetic resonance (MR) imaging for detecting small endometrial implants.

DESIGN

Prospective evaluation by conventional and fat-saturated MR imaging.

SETTING

Shimane Medical University Hospital, Izumo, Japan.

PATIENTS

Fifty-one consecutive patients with clinically suspected pelvic endometriosis.

INTERVENTIONS

Magnetic resonance images < 2 weeks before laparoscopy or laparotomy.

MAIN OUTCOME MEASURE

The location, number, and size of lesions.

RESULTS

Surgery revealed a normal pelvis in 5 patients, endometriosis in 44 (42 with pigmented lesions and 2 with nonpigmented lesions and adhesions), and other cystic lesions in 2. With fat-saturated MR imaging, overall sensitivity, specificity, positive predictive value, and negative predictive value were 89%, 71%, 95%, and 50%, respectively. At surgery, 122 pigmented lesions of endometriosis were detected. Conventional MR images indicated lesions of endometriosis in 74. When fat-saturated images were used, 103 lesions were detected. With conventional MR images, only one of 34 small endometrial implants (2 to 3 mm in diameter) was detected. However, the addition of fat-saturated images increased the detection rate to 15 of 34, and all lesions > 4 mm in diameter.

CONCLUSION

Conventional MR imaging for detecting small endometrial implants was improved by addition of the fat-saturation technique. Therefore, fat-saturation MR imaging is an acceptable for detecting small endometriomas.

[Contamination of hot water supply in office buildings by Legionella pneumophila and some countermeasures]

An assessment of the contamination by Legionella species of hot water supplied to office buildings was made based on 80 samples of water from 3 types of systems as follows: 20 samples supplied from instantaneous heaters, 20 samples from hot water storage type systems, and 40 samples from circulation type systems. Legionella spp. were detected in two samples (10.0%) from hot water storage systems and five samples (12.5%) of the circulation type. The number of Legionella spp. was 2.0 x 10-8.4 x 10(2) CFU/500 ml. All isolated strains were identified as Legionella pneumophila. All hot water samples with Legionella spp. showed a temperature range from 41-55 degrees C. Contamination may easily occur in hot water storage and circulation type systems, due to their presence for prolonged periods. Hot water may be therefor be a source of Legionnaires' disease. It is clear from the present study that Legionella spp. survived over long periods and proliferated considerably. Elimination of this organism requires careful cleaning of hot water storage tanks but this alone may not be sufficient. Heat treatment for 20 hours at 70 degrees C was found to be adequate for complete elimination. Experimentally, complete sterilization from Legionella spp. within 5 minutes was demonstrated by heating at 60 degrees C. As a countermeasure temperature of hot water should be maintained at more than 55 degrees C, as the best means for elimination while also giving consideration to the prevention of scalding.

[A case of idiopathic plasmacytic lymphadenopathy with polyclonal hyperimmunoglobulinemia associated with chronic nephritis]

A 48-year-old female who had general fatigue was admitted to our hospital. She had swelling of the axillary, inguinal, and paraaortic lymph nodes and mediastinal lesions. Laboratory examinations showed anemia, polyclonal hyperimmunoglobulinemia with IgG 5570 mg/dl, renal dysfunction and interstitial changes of the lungs. Microscopic findings of hematoxylin-eosin staining in biopsy specimens of the left inguinal and axillary lymph nodes revealed increased levels of infiltration of mature plasma cells without evidence of malignancy. Immunoperoxidase staining showed intracytoplasmic polyclonal immunoglobulin. These findings were identical to those of idiopathic plasmacytic lymphadenopathy with polyclonal hyperimmunoglobulinemia (IPL) described by Mori et al. (1980). The specimens also showed evidence of chronic nephritis with infiltration of lymph cells and a slight invasion of plasma cells. Accordingly this case was diagnosed as IPL with renal involvement, which is associated with chronic nephritis. Recently, five cases of IPL with renal dysfunction have been reported. In particular, two cases of IPL with renal dysfunction, which included our case, revealed an increased level of IL6. These findings suggest that the occurrence of renal involvement with IPL may be related to changes in IL6, which is an important factor in the pathogenesis of IPL.

Radiotherapy for hepatocellular carcinoma: clinicopathological study of seven autopsy cases

The clinical value of radiotherapy for hepatocellular carcinoma (total tumor dose: 50-70 Gy) was evaluated in seven autopsied patients with nine tumors. A partial response as defined by the WHO criteria for chemotherapy was observed in three tumors (33%). Progressive and marked shrinkage of the noncancerous liver tissue within the irradiated field was also observed in all cases. Histological examination revealed viable cancer cells in all cases. These results indicate that local radiotherapy applying 50-70 Gy achieved some clinical benefit, but was not capable of curing hepatocellular carcinoma.

Therapeutic effect of reticuloendothelial system (RES)-avoiding liposomes containing a phospholipid analogue of 5-fluorouracil, dipalmitoylphosphatidylfluorouridine, in Meth A sarcoma-bearing mice

Reticuloendothelial system (RES)-avoiding liposomes are known to accumulate in tumor tissues due to passive targeting. Dipalmitoylphosphatidylfluorouridine (DPPF), a potent antitumor agent readily incorporated into the lipid bilayer, was embedded in RES-avoiding liposomes modified with a uronic acid derivative, palmityl-D-glucuronide (PGlcUA). The therapeutic effect of DPPF in PGlcUA-liposomes was examined in tumor-bearing mice. Free or liposomal DPPF was injected intravenously into BALB/c mice bearing subcutaneously implanted Meth A sarcomas. The RES-avoiding liposomal formulation using PGlcUA was effective in reducing tumors, and prolonging survival time compared with free DPPF and also DPPF in conventional liposomes. Therefore, PGlcUA-liposomes might be of practical use as drug carriers for anticancer agents, especially their derivatives for embedding in liposomal membranes.

Microvasculature of the lingual papillae in primates and insectivores--fungiform, vallate and foliate papillae

The microvascular architecture of the fungiform, vallate and foliate papillae was investigated under scanning electron microscope in man, common squirrel monkeys, common marmosets, common tree shrews (primates), large Japanese moles and dwarf shrews (insectivores) utilizing microvascular corrosion casts. The fungiform papilla of the lingual apex in man was supplied by an intrapapillary capillary network with a globular pattern. It was composed of 10-15 capillary loops in a circular arrangement and 5-7 thick capillaries in the center. The fungiform papilla of the lingual body was supplied by a dense capillary network on the top and lateral surfaces. That in other primates was supplied by a cylindrical capillary network and loop formation was seen on the top surface. That in insectivores was supplied by a thin cylindrical network with coarse meshes, at the tips of which were observed 2 or 3 capillary rings in the mole and only one in the dwarf shrew. The vallate papilla in primates was supplied by an intrapapillary capillary network with a globular pattern, and showed irregularly tortuous capillary loops on its top surface. The vallum was supplied by a capillary network in man and usually one or two rows of loops arranged in a circle in other primates. The vallate papilla in insectivores was supplied by a doughnut-like capillary network with a recess on the top surface, and an indistinctly low vallum by a low undulating network. The foliate papillae were most developed in man, and each lobule was supplied by capillaries passing longitudinal to it and capillary loops in 5-10 regular rows on the top, but 3-5 rudimentary lobules in the squirrel monkey and marmoset. In the two species, each lobule was supplied by one arteriole, one venule and a coarse capillary network continuing from the interpapillary network. No foliate papilla was observed, but large conical papillae were noted in the tree shrew and insectivores. In conclusion, the intrapapillary vasculature appeared most complicated in man, simplified in the squirrel monkey and marmoset, and was much more simplified in the insectivores, where it was quite different from that in the primates. The pattern of the intrapapillary vasculature in the tree shrew was transitional between primates and insectivores.

Localization in rat brain of the trace metals, zinc and manganese, after intracerebroventricular injection

Autoradiographic studies of rat brain, after 65ZnCl2 or 54MnCl2 injection into the lateral ventricle, revealed that 65Zn and 54Mn were transferred freely through the cerebrospinal and extracellular fluid compartments; both tracers appeared in all the ventricles 1 h after injection. At 6 days after injection, 65Zn was concentrated in the hippocampal formation and hypothalamic nuclei but not in the cerebral cortex and superior colliculus of the ipsilateral hemisphere, with a lower uptake into contralateral hemisphere except for the hypothalamic nuclei. 54Mn was concentrated in some brainstem nuclei, such as the red and pontine reticular nuclei, to about the same extent in both hemispheres. These results suggest that both metals were taken up gradually into brain mainly via the cerebrospinal fluid. Relatively high uptake of 65Zn into the cerebral cortex and superior colliculus after intravenous injection suggests uptake in those regions is through two blood/brain barriers.

Purification and characterization of galactocerebrosidase from human lymphocytes

Galactocerebrosidase was purified about 22,600-fold using several hydrophobic column and gel filtration steps with a 4.8% recovery, from human lymphocytes. Its specific activity was 1.54 x 10(5) nmol/h/mg with tritium-labeled galactocerebroside as the substrate in the taurocholate system. The optimal pH for galactocerebroside was 4.2 in the taurocholate system and 4.6 in the cholate system. The Km values for galactocerebroside were 5 microM in the taurocholate system and 25 microM in the cholate system. The molecular weight of the purified enzyme was estimated to be 90 kDa by sodium dodecylsulfate polyacrylamide gel electrophoresis and gel filtration. However, 70, 50, 40, and 30 kDa bands were also recognized on SDS-PAGE. The N-terminal amino acid sequences of the 70 kDa molecule and the three 50 kDa molecules were the same as that of the 90 kDa molecule. The N-terminal amino acid sequences of the 40 and 30 kDa molecules were unique. A monoclonal antibody raised against the purified enzyme effectively immunoprecipitated galactocerebrosidase activity, and an affinity column prepared with this monoclonal antibody bound the 90 and 50 kDa proteins. These results suggest that this enzyme is probably processed from the 90 kDa protein.

[Microbiological and clinical studies of vancomycin resistant Leuconostoc spp. and Pediococcus spp. isolated from septicemia patients]

We described three septicemia cases in which blood cultures yielded gram-positive cocci identified as Leuconostoc spp. and Pediococcus spp. Patients were three male adults aged 63 to 71 years with severe underlying diseases, pancreatic cancer, esophageal cancer and diabetes mellitus with chronic renal failure. They had fever and chills at the onsets of septicemia with acute obstructive suppurative cholangitis, acute pneumonia, and infection complicated with invasion sites of esophageal cancer contagious to bronchus and subcutaneous tissue. Blood cultures yielded catalase and oxidase negative highly vancomycin-resistant (MIC: 1024 micrograms/ml <) gram-positive cocci showing alpha or gamma hemolysis on blood agar plates. Two cases were polymicrobial infections. In one case with esophageal cancer, clinical symptoms persisted after the start of antimicrobial chemotherapy and the patient died 10 days later associated with complications of esophageal cancer. Leuconostoc lactis, Leuconostoc mesenteroides subsp. dextranicum, and Pediococcus acidilactici wee identified by physiological reactions. These strains were also highly resistant to teicoplanin and fosfomycin, and tolerant to all rested beta-lactams such as benzylpenicillin. This is the first report in Japan to our knowledge on the identification of Leuconostoc spp. and Pediococcus spp. isolated from human infectious diseases.

Induction of lung-specific DNA damage by metabolically methylated arsenics via the production of free radicals

To clarify the genotoxicity of inorganic arsenics, we focused on the genotoxic effect of metabolically methylated arsenics in mammals. Oral administration to mice of dimethylarsinic acid (DMAA), a major metabolite of inorganic arsenics, induced lung-specific DNA damage, i.e., DNA single-strand breaks and the clumping of heterochromatin. The lung-specific strand breaks were not caused by DMAA itself, but by dimethylarsine, a further metabolite of DMAA. An in vitro experiment indicated that DNA single-strand breaks by dimethylarsine were suppressed by the presence of superoxide dismutase and catalase, suggesting that the strand breaks were induced via the production of free-radical species including active oxygens. Dimethylarsenic peroxyl radical [(CH3)2AsOO.] and superoxide anion radical produced from the reaction between molecular oxygen and dimethylarsine were detected by electron-spin resonance analysis using a spin-trapping agent and the cytochrome-c method, respectively. Of these two radicals, the dimethylarsenic peroxyl radical rather than the superoxide anion radical is assumed to play the dominant role in causing the DNA damage, at least for DNA single-strand breaks.

Effective production of glycosyl-steviosides by alpha-1,6 transglucosylation of dextrin dextranase

Dextrin dextranase (EC 2.4.1.2; DDase), which is produced by Acetobacter capsulatus ATCC 11894, acted on a mixture of stevioside and starch hydrolysate with isoamylase, so that the enzyme was found to convert stevioside to predominantly mono-glucosyl-stevioside (SG1) and di-glucosyl-stevioside (SG2), and little of the stevioside initially added remained. SG1 was separated into two compounds (SG1a and SG1b) by reversed-phase high-pressure liquid chromatography. The structures of SG1a, SG1b, and SG2 were analyzed and concluded to be 13-O-(6-alpha-glucosyl-2-beta-glucosyl-beta-glucosyl)-19-O-beta-glucosyl -steviol, 13-O-[(6-alpha-glucosyl)(2-beta-glucosyl)-beta-glucosyl]-19-O- glucosyl-steviol, and 13-O-[(6-alpha-glucosyl)(6-alpha-glucosyl-2-beta- glucosyl)-beta-glucosyl]-19-O-beta-glucosyl-steviol, respectively. During the reaction for production of glycosyl-steviosides, DDase catalyzes transglucosylations from glucosyl donor compounds to stevioside to be SG1a and SG1b, and to SG1b to be SG2 rapidly forming alpha-1,6 glucosidic linkages. However transglucosylation to SG1a to be SG2 rarely occurred, and the conversions among stevioside and these glycosyl-steviosides were catalyzed by the action of DDase to transfer alpha-1,6 linked glucosyl residues, forming alpha-1,6 linkages.

Properties and active center of the thermostable branching enzyme from Bacillus stearothermophilus

Although the branching enzyme (EC 2.4.1.18) is a member of the alpha-amylase family, the characteristics are not understood. The thermostable branching enzyme gene from Bacillus stearothermophilus TRBE14 was cloned and expressed in Escherichia coli. The branching enzyme was purified to homogeneity, and various enzymatic properties were analyzed by our improved assay method. About 80% of activity was retained when the enzyme was heated at 60 degrees C for 30 min, and the optimum temperature for activity was around 50 degrees C. The enzyme was stable in the range of pH 7.5 to 9.5, and the optimum pH was 7.5. The nucleotide sequence of the gene was determined, and the active center of the enzyme was analyzed by means of site-directed mutagenesis. The catalytic residues were tentatively identified as two Asp residues and a Glu residue by comparison of the amino acid sequences of various branching enzymes from different sources and enzymes of the alpha-amylase family. When the Asp residues and Glu were replaced by Asn and Gln, respectively, the branching enzyme activities disappeared. The results suggested that these three residues are the catalytic residues and that the catalytic mechanism of the branching enzyme is basically identical to that of alpha-amylase. On the basis of these results, four conserved regions including catalytic residues and most of the substrate-binding residues of various branching enzymes are proposed.

DNA damage induced in cultured human alveolar (L-132) cells by exposure to dimethylarsinic acid

Gene damage in cultured human alveolar (L-132) cells induced by exposure to dimethylarsinic acid (DMAA), a major metabolite of inorganic arsenics in mammals, was studied. DNA single-strand breaks and DNA-protein cross-links were induced by the treatment of L-132 cells with 10 mM DMAA. These kinds of damage appeared at 8 hr after start of exposure to DMAA. As regards DNA-protein cross-links, the DNA was found to bind not only to core histone proteins but also linker histone (H1) and nonhistone proteins. Furthermore, the cross-links were formed by the binding to serine or threonine residues of H1 or nonhistone proteins through phosphate moieties of the DNA. The induction of the alkali-labile sites in DNA in DMAA-treated L-132 cells was observed prior to that of DNA single-strand breaks and DNA-protein cross-links. As one of the alkali-labile sites in DNA, we estimated apurinic/apyrimidinic (AP) sites in DNA. The present study suggests that the DNA single-strand breaks and DNA-protein cross-links induced by the treatment of L-132 cells with DMAA occurred via the formation of AP sites in the DNA and that the DNA-protein cross-links were produced by a Schiff-base reaction between amino groups of nuclear proteins and aldehyde groups of AP sites in the DNA and the DNA single-strand breaks, by a beta-elimination reaction on AP sites in the DNA.

[Evaluation of anticoagulant activity for low molecular-weight heparin by chromogenic substrate. Measurement of factor Xa and thrombin activities]

We described an amidolytic method for determining the anticoagulant activity of commercially available low molecular-weight heparin (LMWH) with the use of factor Xa (FXa) and thrombin (FIIa), and a chromogenic peptidyl substrate, S-2222 or S-2238. The procedures were based on the photometric determination of the inactivation of FXa and FIIa after incubation with LMWH in the presence of antithrombin III (AT III). At first, the optimal conditions of FXa and FIIa activities with respect to pH, temperature, and the amounts of AT III and LMWH-International Standards (LMWH-IS) were determined. And then, the anticoagulant activities of various LMWHs were determined under the established conditions. In the comparative study with LMWHs, significant differences were found in anti FXa and anti FIIa activities, and their ratios. The anti FIIa activity was reconfirmed to decrease with decreasing molecular weight of LMWHs. On the other hand, the anti Xa activity was, however, less dependent on the molecular weight of LMWHs.

Classification of some alpha-glucosidases and alpha-xylosidases on the basis of substrate specificity

Three alpha-glucosidases which passed under the names of transglucosidase (from Aspergillus niger), maltase (from Brewers yeast), and isomaltase (from Bakers yeast) for reasons of their substrate specificities and transfer actions, were purified to electrophoretically pure states. These purified alpha-glucosidases were made uniform in the hydrolyzing activities using p-nitrophenyl alpha-glucopyranoside (alpha-p-NPG) and were reacted with p-nitrophenyl alpha-xylopyranoside (alpha-p-NPX) or isoprimeverose (xylopyranosyl-alpha-1,6-glucopyranose), which are typical substrates of alpha-xylosidase. Only Asp. niger alpha-glucosidase among them hydrolyzed alpha-p-NPX and isoprimeverose. Further the substrate specificities of three alpha-glucosidases and two alpha-xylosidases (I and II from Asp. flavus MO-5) were investigated on maltose, isomaltose, alpha-p-NPG, isoprimeverose, and alpha-p-NPX in detail, and kinetic parameters [Km, Vmax, and molecular activity (Ko)] were estimated and compared with each other. In the comparison of kinetic parameters, Asp. niger alpha-glucosidase showed a broad specificity, that is, containing isoprimeverose in addition to maltose, isomaltose, and alpha-p-NPG. Though this enzyme barely hydrolyzed alpha-p-NPX too, the velocity was very slow. Though both yeast alpha-glucosidases barely hydrolyzed alpha-p-NPX or isoprimeverose too, these substrates were not good for yeast enzymes. On the other hand, two alpha-xylosidases showed narrow specificities, such that the substrates except for alpha-p-NPX and isoprimeverose were not hydrolyzed at all. The action on isoprimerose by Asp. niger alpha-glucosidase was completely the same as that on isomaltose at optimum pH, optimum temperature, inhibition pattern of hydrolyzing activity by 1-deoxynojirimycin, and transfer action pattern. Accordingly, we interpret these results as indicating that the hydrolyzations of isomaltose and isoprimeverose by Asp. niger alpha-glucosidase were catalyzed at the same active site. Asp. niger enzyme that has both alpha-glucosidase activity and alpha-xylosidase activity was shown to be classified in a middle position between alpha-glucosidase and alpha-xylosidase.