Specific targeting of mitomycin C to tumors by anti-gastric cancer monoclonal antibody

In the present study, an anti-gastric cancer monoclonal antibody, MGb2, was chosen to prepare antibody-mitomycin C (MMC) conjugate with dextran T-40 as intermediary. Twenty molecules of MMC were introduced into each molecule of antibody while the antigen-binding capacity of the antibody was kept well. The conjugate showed selective cytotoxicity upon human gastric cancer cell line SGC-7901. Radioimmunoimaging and biodistribution studies indicated that after conjugation with MMC via dextran T-40 as intermediary, the tumor localization capacity of the antibody was well retained. When tested in nude mice, inoculated with human gastric carcinoma SGC-7901 in bilateral subrenal capsules, intraperitoneal injection of the conjugate daily for 6 days at a dose of 1 mg/kg gave a tumor inhibitory rate of 68.67%, which was far better than that of free MMC or irrelevant conjugate. No synergetic effect was found in regard to the mixture of MGb2 with MMC.

Diagnostic significance of gastric cancer associated antigens (MG-AGS) in serum, ascitic fluid and gastric juice

A group of monoclonal antibodies against gastric cancer, pooled in equal proportions, was used to investigate their corresponding antigens (MG-Ags) in serum and body fluid of patients with gastrointestinal cancer and benign diseases using microsphere-ELISA method. The mean serum level (plus 3 standard deviations) in 59 normal subjects was arbitrarily set as the positive threshold value. The positive rate was found to be 68.8% (135/196) in sera of patients with gastric cancer, 70% (14/20) in colonic cancer, 72.2% (24/33) in rectal cancer, 43.8% (7/16) in esophageal cancer, 45.5% (5/11) in cholecystic cancer and 34.9% (15/43) in lung cancer, which, however, was not found in primary liver cancer, pancreatic cancer and ovarian cancer. In 214 patients with benign diseases, a false positive rate was 7.48%. In gastric juice and ascitic fluid of patients with gastric cancer, the positive rates were found to be 61.7% (27/44) and 83.3% (20/24) respectively. These antigens were also determined repeatedly in sera of patients with gastric cancer who had undergone gastrectomy. It was found that the level of MG-Ags in sera began to decrease at 8-10 days after operation. These results suggest that the determination of MG-Ags is useful in the diagnosis of gastrointestinal cancer and evaluation of the treatments.

Purification and partial characterization of a new group of gastric cancer associated antigens

The corresponding antigens of MG series monoclonal antibodies (MG5, MG9, MGd1 and MGe1) against gastric cancer were purified and partially characterized. Each of these monoclonal antibodies was purified by passing through a DEAE-52 cellulose columns and covalently coupled with CNBr-activated sepharose 4B successively. By means of concanavalin A and antibody affinity chromatography, the corresponding antigens of MG series McAb were extracted from gastric cancer tissue respectively. Immunological and biochemical studies confirmed that the corresponding antigens of MG series McAb were a new group of gastric cancer associated neutral glycolipid and glycoprotein antigens.

[Prognostic factors and treatment of severe acute pancreatitis]

Seventy two cases of severe acute pancreatitis (SAP) all documented by laparotomy. Fifteen were found to be of edematous and 58 of hemorrhagic and necrotic type, 29 cases died (39.7%). The following 6 items are of prognostic importance in both the survival and the dead groups: (1) Shock, (2) Serum albumin less than 30 g/L. (3) BUN greater than 7 mmol/L, (4) Blood glucose greater than 11.1 mmol/L, (5) Abnormal urine analysis, (6) PaO2 less than 8.6 kPa. Thirty two cases showed positivity of 3 or more of the 6 items, among them 21 died (65.6%). Fourty one cases had 2 or less positive items and 8 (19.5%) died. The mortality rate was not significantly different between the group who had either the edematous or the hemorrhagic necrotizing varieties. It was found that 88.2% of the patients in the dead group had hemorrhagic and necrotizing variety in the peripancreatic and similar pathology appeared in the survival group only in 50% (P less than 0.05). The risk was markedly increased in these patients with systemic complication in the lungs, kidney and brain. We found no effect of vasodilatation drugs (salvia miltiorrhiza and anisodamine) in the treatment of SAP.

Binding sites in mammalian genes and viral gene regulatory regions recognized by methylated DNA-binding protein

Methylated DNA-binding protein (MDBP), a ubiquitous mammalian protein, recognizes a variety of related DNA sequences. Some of these sequences require methylation of their CpG dinucleotides for binding and others do not. We report that MDBP binds, in a DNA methylation-independent fashion, to two sites in the mouse polyomavirus enhancer, one in the enhancer of the human hepatitis B virus, and to one in the long terminal repeat of equine infectious anemia proviral DNA. We have also found a number of MDBP sites in human and rodent DNAs which bind much better to MDBP when they are methylated at CpG dinucleotides within the recognition site. These include sites at the beginning of the human genes for hypoxanthine phosphoribosyl transferase, HLA-A2, -A3, and -A25 antigens, and alpha-galactosidase A. In the case of methylation-responsive MDBP sites, changes in their methylation status during differentiation or DNA replication could help drive development by modulating transcription.

An MDBP site in the first intron of the human c-myc gene

The expression of the human c-myc protooncogene is subject to many levels and types of control. Evidence suggests that regulation of the expression of this gene involves elements within the gene as well as those upstream from the gene. We show that a ubiquitous mammalian sequence-specific DNA-binding protein, MDBP, binds specifically to a site in the beginning of the first intron of this gene. This protein, which binds to certain viral enhancers, may be helping to control expression of the c-myc gene. In some Burkitt lymphomas, which contain activated c-myc genes, the MDBP site is lost by chromosome rearrangement or by multiple spontaneous mutations. This might contribute to cancer-related activation of this protooncogene.

Metastatic calcification within bone. The main cause of osteosclerosis in hypervitaminosis D3. Radiologic-pathologic correlation

Because the pathogenesis of osteosclerosis in hypervitaminosis D is still not well elucidated, the authors experimentally studied hypervitaminosis D3 in 66 rabbits by injecting different doses of vitamin D3. Contact radiographs of bone specimens showed various signs of osteosclerosis, including dense epiphyses and metaphyses, thickened bony articular surfaces, dense metaphyseal bands, modeling defects at the metaphysis, and dense and thickened cortical bone. The corresponding pathologic sections showed that conspicuous metastatic calcification coated the trabeculae and filled bone marrow cavity and caverns in the original but porotic cortical and periosteal new bone. Rather than being resorbed, the metastatic calcifications were embedded in a thick layer of newly formed bone 6 to 14 weeks after vitamin D3 withdrawal. This study suggests that in hypervitaminosis D3, the osteoblasts and bone marrow undergo degeneration, leading to necrosis and calcification. After vitamin D3 withdrawal, osteoblasts reappear and become overactive, leading to overossification.

Effects of dysphoria on maternal exchange dispositions

Defining dysphoria as subclinical depression, we explored the extent to which maternal dysphoria influences the quality of relationships within the family and evaluated whether the effect of dysphoria on family relationships is selective or general and whether dysphoric effects on maternal behavior are similar or different when ratings of maternal behaviors are made by mothers versus observers. We expected that dysphoria would have general rather than selective effects on family relations rated by mothers and observers. In a sample of 40 American families at risk of child abuse or neglect, we found that maternal dysphoria did have significantly negative effects on mother-to-child and mother-to-parenting-partner relations, suggesting that maternal dysphoria has general rather than selective effects.

Stimulation in vitro of lymphocytes for induction of uveoretinitis without any significant proliferation

Experimental autoimmune uveoretinitis can be adoptively transferred into naive recipients by lymphocytes from rats immunized with uveitogenic Ag, provided these cells are activated in vitro before being injected. The activation of sensitized lymphocytes, by the immunizing Ag, or by cross-reacting Ag, is usually accompanied by vigorous proliferation. We report, however, on a complete dissociation between the capacity of a peptide to generate uveitogenicity and to stimulate proliferation in cultured lymphocytes. This peptide, which occupies sequence 579-591 of the bovine interphotoreceptor retinoid-binding protein (IRBP), is one of the three "repeats" that exhibit partial sequence homologies with the immunodominant and highly immunogenic peptide, 1179-1191. Peptide 579-591 is nonimmunogenic and nonuveitogenic in Lewis rats and does not stimulate any significant proliferation in lymphocytes sensitized against whole IRBP, peptide 1179-1191, or another "repeat" peptide, 271-283, which is immunogenic and uveitogenic. In contrast, peptide 579-591 effectively generates uveitogenicity in the lymphocytes sensitized against these three Ag. Unlike 579-591, peptides 271-283 and 1179-1191 stimulated both proliferation and uveitogenicity in these sensitized lymphocytes. A different pattern of activities was observed with the other "repeat" peptide, 880-892. This peptide did not have any effect on the lymphocytes sensitized against IRBP, 271-283 or 1179-1191, but did stimulate both proliferation and uveitogenicity in lymphocytes sensitized against itself. The data suggest that 579-591 selectively stimulates a lymphocyte subset that is uveitogenic, but is incapable of mounting proliferative responses.

Stimulation in vitro of lymphocytes for induction of uveoretinitis without any significant proliferation

Experimental autoimmune uveoretinitis can be adoptively transferred into naive recipients by lymphocytes from rats immunized with uveitogenic Ag, provided these cells are activated in vitro before being injected. The activation of sensitized lymphocytes, by the immunizing Ag, or by cross-reacting Ag, is usually accompanied by vigorous proliferation. We report, however, on a complete dissociation between the capacity of a peptide to generate uveitogenicity and to stimulate proliferation in cultured lymphocytes. This peptide, which occupies sequence 579-591 of the bovine interphotoreceptor retinoid-binding protein (IRBP), is one of the three "repeats" that exhibit partial sequence homologies with the immunodominant and highly immunogenic peptide, 1179-1191. Peptide 579-591 is nonimmunogenic and nonuveitogenic in Lewis rats and does not stimulate any significant proliferation in lymphocytes sensitized against whole IRBP, peptide 1179-1191, or another "repeat" peptide, 271-283, which is immunogenic and uveitogenic. In contrast, peptide 579-591 effectively generates uveitogenicity in the lymphocytes sensitized against these three Ag. Unlike 579-591, peptides 271-283 and 1179-1191 stimulated both proliferation and uveitogenicity in these sensitized lymphocytes. A different pattern of activities was observed with the other "repeat" peptide, 880-892. This peptide did not have any effect on the lymphocytes sensitized against IRBP, 271-283 or 1179-1191, but did stimulate both proliferation and uveitogenicity in lymphocytes sensitized against itself. The data suggest that 579-591 selectively stimulates a lymphocyte subset that is uveitogenic, but is incapable of mounting proliferative responses.

Preparation of antigastric cancer monoclonal antibody MGb2-mitomycin C conjugate with improved antitumor activity

In the present study, an antigastric cancer monoclonal antibody, MGb2, was chosen to prepare antibody-mitomycin C conjugate with dextran T-40 as intermediary. Up to 20 molecules of mitomycin C were specifically bound per molecule of antibody, without significantly impairing the antigen-binding capacity of the antibody and the pharmacological activity of mitomycin C. The conjugate showed selective cytotoxicity upon human gastric cancer cell line SGC-7901 in vitro. Radioimmunoimaging and biodistribution studies indicated that, after conjugation with mitomycin C via dextran T-40 as intermediary, the tumor localization capacity of the antibody was well-retained. When tested in nude mice inoculated with human gastric carcinoma GAII in bilateral subrenal capsules, intraperitoneal injection of the conjugate twice a week for 3 weeks at the dose of 1 mg/kg of drug gave a tumor inhibitory rate of 152.29%, the result being far better than that of free mitomycin C or an irrelevant conjugate. A similar result was found in another nude mouse model of human gastric carcinoma SGC-7901. Meanwhile, after conjugation with antibody, the toxicity of mitomycin C on tested animals was significantly reduced.

Selective cytotoxicity against human tumor cells by an anti-gastric cancer monoclonal antibody-mitomycin C conjugate

An anti-gastric cancer monoclonal antibody, MGb2, was chosen to prepare MGb2-mitomycin C (MMC) conjugate. Four to five molecules of MMC were introduced into each molecule of antibody with the antibody activity well retained. The conjugate showed a highly selective cytotoxicity upon human gastric cancer cells KATO-III. In the 48-h exposure test, the cytotoxic effect of MGb2-MMC upon target cells was similar to that of free MMC, but much greater than that of normal mouse immunoglobulin-MMC conjugate. Instead, the MGb2-MMC showed a statistically less cytotoxic effect upon non-target cells. Imaging and biodistribution studies indicated that the MGb2 was still well localized in tumor tissue after its conjugation with MMC.

Targeted anti-tumor agents and their cytotoxicity on gastric cancer cells in vitro

Several chemotherapeutic drugs including methotrexate, daunomycin, mitomycin C and toxin such as ricin, A chain of ricin were chosen to conjugate with murine monoclonal antibodies MGb2 and MG11. The drugs were linked to antibody directly or through human serum albumin as intermediary. The ELISA results showed that the antibody retained well the antigen-binding capacity during conjugation. These conjugates showed highly selective cytotoxic effect on target cells. In chronic cytotoxicity tests, the cytotoxic effect of these conjugates on human gastric cancer cells KATOIII was quite similar to that of free drugs or ricin, but greater than that of irrelevant conjugates, while they had a little effect on non-target cells, suggesting that the selective cytotoxicity on target cells of the conjugates be mediated by antibodies.

[Perioperative hypophosphatemia in general surgery]

Blood phosphorus was measured in consecutive 136 admitted patients in the department of general surgery between Oct. 1987 and Jan. 1988. It was found that 32 cases (23.5%) were with hypophosphatemia on perioperative period. Sixteen patients with normal preoperative blood phosphorus level undergoing digestive tract surgery were randomly divided into 3 groups, each was fasted for 7 days postoperation and given different kind of transfusions. Group 1, patients were given 250 g of glucose daily with no phosphorus, blood phosphorus level was significantly decreased. Group 2, 250 g of glucose with 7.5 mmol of phosphate daily, blood phosphorus level decreased slightly on the 2nd-4th day and returned back to normal on day 7. Group 3,500 g of glucose with 15 mmol of phosphate daily, blood phosphorus level decreased moderately on the 2nd-4th day, and returned to normal level on day 7. Perioperative hypophosphatemia was attributed to: (1) Poor absorption or massive loss of phosphorus through digestive tract. (2) Intracellular transferring of blood phosphorus accompanied by the phosphorylation of saccharide. (3) Excessive excretion of phosphorus through urine. The authors suggested that 7-9 mmol of phosphates per 100 kcal daily for the prevention and 7-15 mmol of phosphates per 1000 kcal daily for the treatment of hypophosphatemia.

Changes and significance of immunoreactive beta-endorphin in gastric mucosa of patients with benign and malignant gastric diseases

RIA method was used in this study to determine immunoreactive beta-endorphin (ir-beta-EP) in gastric mucosa of patients with benign and malignant gastric diseases. The results showed that the content of ir-beta-EP in gastric mucosa in the peptic ulcer group was the highest (68 +/- 9.5 pg/mg wet weight tissue, P less than 0.01), while its content in gastric carcinoma was closely related to the degree of differentiation of the tumor, that is, in poorly differentiated carcinoma it was lower than that in well differentiated carcinoma (P less than 0.02), and was also lower than that in gastritis (P less than 0.05). At the same time, we found that beta-endorphin can markedly augment the 3H-TdR incorporation of lymphocytes (P less than 0.01). This effect was not blocked by naloxone.

Mutations affecting primer RNA interaction with the replication repressor RNA I in plasmid CoIE1: potential RNA folding pathway mutants

The control of plasmid ColE1 copy number is mediated by the kinetics of interaction of two complementary plasmid-encoded RNAs. One RNA is the primer precursor and the other is a small counter-transcript called RNA I. The interaction of these highly structured RNAs results in inhibition of formation of mature primer RNA necessary for replication initiation. We have studied several plasmid copy number mutants which have single base changes in the primer which render the primer resistant to inhibition by RNA I despite the fact that the mutations are located outside the overlap between primer and RNA I. We propose a model to account for the resistance of the mutant primers which is based on the differential folding of the nascent primer transcripts during transcription. We propose that the mutant primers diverge in structure from their wild-type counterparts during a discrete period during transcription. During this brief divergence, they are proposed to interact kinetically more slowly with RNA I than wild-type primer because a particular domain (the anti-tail) required for efficient interaction with RNA I is buried in a stem-loop structure while this same domain is predicted to be single-stranded in the wild-type. Despite substantial sequence divergence from ColE1, the primer precursors of the related plasmids CloDF13, RSF1030 and p15A also have retained the potential to expose their anti-tail in a similar manner to ColE1, suggesting that the folding pathway has been conserved in evolution.(ABSTRACT TRUNCATED AT 250 WORDS)

[Acute anterior uveitis and HLA]

50 patients with acute anterior uveitis and 52 controls were studied their typing with HLA-A, -B, -C antigens. It was found that HLA-B27 occurred in 23 (46%) of the 50 patients, but only in 2 (3.9%) of the 52 controls (P less than 0.001). With reference to the clinical features, the HLA-B27 positive patients were characterized by their predilection for the male and severe visual impairment with white fine KP, strong Tyndall's phenomenon and marked reaction in the anterior chamber, and little posterior synechia of iris. Of particular interest was that 14 (60.9%) of the 23 HLA-B27 positive patients had plastic exudates in the anterior chamber, while this occurred only in one of the 27 HLA-B27 negative patients who had mutton fat KP. It seemed that there was an association between the plastic exudates in the anterior chamber and HLA-B27, and the clinical significance was discussed.

Studies on gastrin in duodenal ulcer

By immunocytochemical method and radioimmunoassay, the gastrin secreting cells (G cells) and gastrin concentration in antral mucosa, gastric juice and serum in 20 patients with duodenal ulcer (DU) were studied. The number of G cells and gastrin concentration in antral mucosa showed no significant difference as compared with normal control. The number of G cells in patients with DU and antral atrophy was much higher than those with antral atrophy but with DU. It indicated that G cells were increased in number in DU, and the gastrin concentration in gastric juice (271.11 +/- 255.25 pg/ml) was much higher than in sera (74.71 +/- 43.07 pg/ml). G cells were distributed in different parts of pyloric glands, showing that gastrin in gastric juice should come directly from G cells. The disturbance of feedback mechanism in regulating gastric acidity might be an important role in hypersecretion of gastric acid in DU. The increase of gastrin concentration in gastric juice might be closely related to hyperplasia of parietal cells.

[Detection of gastric cancer associated antigens in ascitic and pleural fluid for ascertaining the nature of the exudate]

A new group of gastric cancer associated antigens (MG-Ag) in ascitic fluid and pleural effusion was detected. First of all, the monoclonal antibodies (MG series) were purified and coupled to the miniglobules. The samples to be examined were then mixed with the MG-miniglobules to react. After being blocked by serum of normal mouse, the MG-miniglobules were mixed and made to react with the monoclonal antibodies labeled with HRP. With ELISA method, the MG-Ag levels in ascitic and pleural fluid were determined in 171 patients. The mean value of 87 non-malignant patients plus 3 standard deviations was arbitrarily set as the highest normal limit. Values above this limit were found in 39 (75%) of 52 patients with lung cancer and 20 (83%) of 24 patients with gastric cancer. The MG-Ag level was elevated in 4 (4.6%) of 87 patients with benign diseases. It is not elevated in 8 patients with ovarian cancer. It is suggested that determination of MG-Ag in ascitic and pleural fluid can be used for ascertaining the nature of ascites and pleural effusion.

How different DNA sequences are recognized by a DNA-binding protein: effects of partial proteolysis

MDBP is a sequence-specific DNA-binding protein from mammals that recognizes a variety of DNA sequences, all of which show much homology to a partially palindromic 14 base-pair consensus sequence. MDBP subjected to limited proteolysis and then incubated with various specific oligonucleotide duplexes yielded two types of complexes. The relative concentrations of these complexes varied greatly depending on how closely the MDBP site matched the consensus sequence. No such DNA sequence-specific differences in the types of complexes formed were seen with intact MDBP. Partial proteolysis also changed the relative affinity of MDBP for several of its binding sites. The nature of the two types of complexes formed from fragmented MDBP and DNA was studied by DNA competition assays, protein titration, site-directed mutagenesis, and dimethyl sulfate and missing base interference assays. The results suggest that, for some specific DNA sequences, half-site interactions with one MDBP subunit predominate and for others, strong interaction of two subunits with both half-sites readily occur.

DNA amplification in Streptomyces achromogenes subsp. rubradiris is accompanied by a deletion, and the amplified sequences are conditionally stable and can be eliminated by two pathways

Southern blot analysis of BglII-digested DNA isolated from wild-type Streptomyces achromogenes, which harbors the 8.8-kilobase amplifiable unit of DNA, AUD-Sar 1, and of similarly digested DNA from 12 strains carrying an array of 200 to 300 tandem copies of a specific AUD-Sar 1-derived 8.0-kilobase DNA sequence, ADS-Sar 1, revealed the absence of the 12.4-kilobase BglII AUD-Sar 1-chromosome right junction band in the latter strains, whereas the corresponding 26.0-kilobase left junction band remained unaltered. Further Southern analyses indicated in all of the seven amplified strains tested the occurrence of a deletion of at least 10 kilobases of the DNA adjacent to the right side of the AUD. The deletion has one endpoint in the vicinity of the ADS array. Corroborating and expanding upon previously reported results, we found that the amplified DNA of strain C010 was stably maintained for at least 20 transfers when the transfers involved mycelia propagated in spectinomycin-free liquid medium. In contrast, when strain C010 was subjected separately to one cycle of protoplast formation and regeneration or to three cycles of spore germination, aerial mycelium formation, and sporulation on spectinomycin-free media, only approximately 20% of the protoplast regenerants and spores retained the reiterated DNA sequences and the ability subsequently to form colonies on media containing high levels of spectinomycin. Approximately 80% of these units completely deleted the reiterated DNA and left adjacent sequences and exhibited sensitivity to 25 micrograms of spectinomycin per ml. One among 24 protoplast-derived deletants apparently retained the left portion of the AUD-ADS left direct repeat plus left adjacent sequences.

[Clinicopathologic correlation of lupus nephritis]

26 autopsies and 29 renal biopsies of lupus nephritis were done and examined with pathohistologic methods. They consisted of minor type 2 cases (3.6%), mesangioproliferative type 11 cases (20.0%), focal type 10 cases (18.2%), diffuse proliferative type 17 cases (30.9%), membranous type 13 cases (23.6%) and proliferosclerosing type 2 cases (3.6%). It was found that varied and atypical glomerular lesions, glomerular massive immune complex deposits and wire loop formation, fibrin necrosis, microthrombi formation, arteritis, interstitial inflammation and hematoxyphil bodies formation were common lesions for lupus nephritis. These lesions were indices of activity and progression of lupus nephritis.

[Progesterone receptors in endometrial carcinoma and their response to medroxyprogesterone acetate]

Progesterone receptors (PR) were measured in 18 cases of endometrial carcinoma using the dextran-coated charcoal assay. The histological changes and PR levels of the endometrial carcinoma after the medroxyprogesterone acetate (MPA) treatment were studied. A higher PR levels were observed in well-differentiated tumors. After treatment with MPA, the PR content was reduced and histological appearance similar to normal endometrium was noticed. The histological changes of the tumor was closely related to the receptor levels.

[Laparoscopy in the diagnosis of polycystic ovarian syndrome]

From March 1980 through June 1986, 93 patients clinically diagnosed as having polycystic ovarian syndrome (PCOS) were subject to laparoscopic examinations and laparoscopic ovarian biopsy. After statistical analysis of the results of the study, two improved diagnostic criteria for PCOS were suggested and compared with those proposed by Wortsman, et al and Stein-Leventhal. We think that the two improved diagnostic criteria are more suitable to the clinical practice and increase the diagnostic rate of PCOS to be 85% and 74% respectively. No operative complications such as intraabdominal hemorrhage, mechanical or electric injuries or infection was observed. The accuracy and criteria of laparoscopic diagnosis of PCOS are discussed.

Primary study of attenuated live hepatitis A vaccine (H2 strain) in humans

Strain H2, an attenuated live hepatitis A virus (HAV), was derived from the fecal specimen of a patient with hepatitis A in Hangzhou, China. After isolation and passage in a culture of newborn monkey kidney cells, adaptation to grow in human lung diploid cells (KMB17), and serial passage at a low temperature (32 degrees C) in KMB17 cells, this strain became the master seed virus for H2-strain vaccine. Twelve human volunteers received the experimental vaccine subcutaneously and were closely observed for 20 w. None of the subjects developed any local or systemic reactions, and there were no elevations of serum glutamic-pyruvic transaminase, type 5 isoenzyme of lactate dehydrogenase, or isocitrate dehydrogenase. Seroconversion occurred in all subjects at a mean time of 3 w after inoculation. ELISA competitive test for titer of antibody to HAV showed values ranging from 1:2 to 1:8 with a geometric mean titer of 1:3.48 at 20 w after inoculation. No marked decrease in titer of HAV antibody was found in the subjects tested at 1 y. These antibodies were proved to be neutralizing antibodies.

[Observation of oral glucose-insulin releasing test in liver cirrhosis]

In order to investigate the disorders of carbohydrate metabolism and insulin secretion as well as their correlation in patients with liver cirrhosis, we performed an oral glucose tolerance test on 30 patients with liver cirrhosis proven by history, clinical findings, liver function test, radioisotope liver scanning, ultrasonic examination, gastroscopy, barium esophagogram and liver biopsy, compared with 20 healthy controls. Blood glucose and immunoreactive insulin were determined in both groups at 60 min intervals for 180 min. Results showed marked glucose intolerance with peak value 60 min after glucose load in cirrhotic patients with normal fasting blood glucose. Plasma IRI levels were significantly higher in cirrhotic patients than in normal subjects after glucose load (P less than 0.05), especially 180 min after (P less than 0.01). Twelve of 30 cases (40%) showed an abnormal OGTT curve. Of the 12 cases seven (23.3%) showed a diabetic OGTT curve, five (16.7%) an impaired OGTT curve. While eighteen of 30 cases (60%) showed an abnormal OGIRT curve. Among the 18 cases one (3.3%) presented hypersecretic OGIRT curve, twelve (40.0%) with delayed and prolonged peak, and five (16.7%) with hypersecretic OGIRT curve and delayed, prolonged peak.

Related sites in human and herpesvirus DNA recognized by methylated DNA-binding protein from human placenta

Methylated DNA-binding protein (MDBP) from mammalian cells binds specifically to six pBR322 and M13mp8 DNA sequences but only when they are methylated at their CpG dinucleotide pairs. We cloned three high-affinity MDBP recognition sites from the human genome on the basis of their binding to MDBP. These showed much homology to the previously characterized prokaryotic sites. However, the human sites exhibited methylation-independent binding apparently because of the replacement of m5C residues with T residues. We also identified three other MDBP sites in the herpes simplex virus type 1 genome, two of which require in vitro CpG methylation for binding and are in the upstream regions of viral genes. A comparison of MDBP sites leads to the following partially symmetrical consensus sequence for MDBP recognition sites: 5'-R T m5Y R Y Y A m5Y R G m5Y R A Y-3'; m5Y (m5C or T), R (A or G), Y (C or T). This consensus sequence displays an unusually high degree of degeneracy. Also, interesting deviations from this consensus sequence, including a one base-pair deletion in the middle, are sometimes observed in high-affinity MDBP sites.

Human methylated DNA-binding protein. Determinants of a pBR322 recognition site

Methylated DNA-binding protein (MDBP) from human placenta has a high affinity for a site in pBR322 (pB site 1) when that site is methylated at its CpG dinucleotides. Dimethyl sulfate interference analysis and experiments with ligands prepared by oligonucleotide-directed mutagenesis indicate that 15 contiguous base pairs, 14 of which exhibit hyphenated dyad symmetry, influence MDBP binding to pB site 1. These 14 base pairs, 5'-RTMGYCAMGG(M/T)GAY-3' (M, 5-methylcytosine), suffice for recognition by MDBP as demonstrated with a double-stranded, MpG-containing oligonucleotide used as a free ligand or cloned into M13mp19 and subsequently methylated. Seven single-site mutations at different positions of this 14-base pair region largely eliminated binding, and several others increased binding up to 2-fold when compared to the nonmutant, triply methylated sequence. However, MDBP recognizes a site in hemimethylated M13mp19 replicative form DNA, which was homology to pB site 1 at only 10 of 14 base pairs, and all four of these different base pairs are equivalent to transversions. Based upon the above data, a mixed oligonucleotide probe was constructed that contains variants of pB site 1 which should be recognized by MDBP. This 14-base probe hybridizes under stringent conditions to a number of discrete fragments in restriction digests of human DNA. this suggests that there are multiple pB site 1-related sequences in human DNA that might, when methylated, bind MDBP in vivo.

Conditional high copy number ColE1 mutants: resistance to RNA1 inhibition in vivo and in vitro

We describe three independently isolated copy number mutants of a plasmid ColE1 derivative which undergo temperature- and growth-phase-dependent DNA amplification in Escherichia coli. These mutants have single base-pair alterations in a highly localized region of the plasmid genome encoding the replication primer RNA. The mutations map immediately upstream of the RNA1 transcript, altering the sequence between conserved elements of the RNA1 promoter. These mutants have 2- to 4-fold increased copy number relative to wild-type plasmids in exponential growth at 37 degrees C but undergo 20-fold amplification of copy number relative to wild-type when cells enter stationary phase. Cells containing these plasmids grow with normal kinetics at 37 degrees C but grow poorly at 42 degrees C. The poor growth is associated with high-level plasmid amplification. Both the temperature and growth phase plasmid DNA amplification are suppressed if the ColE1 rop gene product is provided in trans from a compatible plasmid. Analysis of steady-state RNA1 levels indicates that DNA amplification occurs in the presence of RNA1 made by the mutant plasmid. Thus, the DNA amplification of the copy mutant is not due to an inability to synthesize RNA1. Using an in vitro transcription system containing RNase H, we show that mutant primer processing by RNase H is resistant to levels of the replication initiation inhibitor RNA1 that inhibit wild-type primer processing. The defect in inhibition appears not to be at the level of association of RNA1 with nascent primer. These results indicate that mutant plasmid amplification is due to the ability of its primer precursor transcripts to serve as substrates for RNase H despite the presence of RNA1.

Effects of traces of rare earth elements on the protozoan Blepherisma and on mice

The growth of the protozoan Blepherisma is stimulated by Lanthanum (La) at concentrations as low as 0.32 ppm. In mice Yttrium (Y) and Ytterbium (Yb) are absorbed, accumulated, and metabolized. Both rare earth elements (RE) exhibit a high affinity for teeth and bones, accumulation occurs and metabolism is slow. In the livers of RE-exposed mice, concentrations are variable. The liver is apparently capable of absorbing and discharging RE in a manner depending on metabolic activity. The main route of discharge for ingested REs is the alimentary canal. Exposure of pregnant mice to RE leads to rapid placental transfer of RE; 14.1% of the total amount of RE administered was detected in newborn mice. Young, developing organisms appear to be especially susceptible to RE accumulation.

Methylated DNA-binding protein is present in various mammalian cell types

A DNA-binding protein from human placenta, methylated DNA-binding protein (MDBP), binds to certain DNA sequences only when they contain 5-methylcytosine (m5C) residues at specific positions. We found a very similar DNA-binding activity in nuclear extracts of rat tissues, calf thymus, human embryonal carcinoma cells, HeLa cells, and mouse LTK cells. Like human placental MDBP, the analogous DNA-binding proteins from the above mammalian cell lines formed a number of different low-electrophoretic-mobility complexes with a 14-bp MDBP-specific oligonucleotide duplex. All of these complexes exhibited the same DNA methylation specificity and DNA sequence specificity. From the extracts of rat and calf tissues, oligonucleotide protein complexes formed that also had the same specificity as human placental MDBP although they had a higher electrophoretic mobility probably due to digestion by proteases in the nuclear extracts. Although MDBP activity was found in various mammalian cell types, it was not detected in extracts of cultured mosquito cells and so may be associated only with cells with vertebrate-type DNA methylation.

[In vitro synthesis of SIgA and CEA and their relationship in gastric cancer tissue]

The in vitro synthesis of secretory immunoglobulin A (SIgA) and carcinoembryonic antigen (CEA) was observed by tissue culture of biopsied gastric cancer tissue and gastric mucosa in other gastric diseases. The level of SIgA Synthesis in cultured gastric cancer tissue was lower than that in gastric mucosa in chronic atrophic gastritis, chronic superficial gastritis and normal stomach. The gastric mucosa of chronic gastritis can produce more SIgA than the normal gastric tissue, but the difference between chronic atrophic gastritis and chronic superficial gastritis was of no statistical significance. The CEA level was significantly higher in cancerous tissue than that in noncancerous ones, the amount of CEA synthesis by gastric mucosa in chronic atrophic gastritis was higher than that in chronic superficial gastritis and normal stomach. Well differentiated adenocarcinoma secreted much more SIgA and CEA than the poor-differentiated ones. The results suggest that the estimation of secretory function of SIgA and CEA be helpful for clinical diagnosis of gastric cancer.

Hypermethylation of human DNA sequences in embryonal carcinoma cells and somatic tissues but not in sperm

Certain human DNA sequences are much less methylated at CpG sites in sperm than in various adult somatic tissues. The DNA of term placenta displays intermediate levels of methylation at these sequences (Sp-0.3 sequences). We report here that pluripotent embryonal carcinoma (EC) cells derived from testicular germ cell tumors are hypermethylated at the three previously cloned Sp-0.3 sequences and seven newly isolated sequences that exhibit sperm-specific hypomethylation. In contrast to their hypermethylation in EC cells, the Sp-0.3 sequences are hypomethylated in a line of yolk sac carcinoma cells, which like placenta, represent an extraembryonic lineage. These DNA sequences, therefore, appear to be subject to coordinate changes in their methylation during differentiation, probably early in embryogenesis, despite their diversity in copy number (1 to 10(4] and primary structure. Two of these Sp-0.3 sequences are highly homologous to DNA sequences in human chromosomal regions that might be recombination hotspots, namely, a cryptic satellite DNA sequence at a fragile site and the downstream region of the beta-globin gene cluster.

Inhibition of streptomycin-dependent mutation in Escherichia coli on the lytic growth of bacteriophage lambda

Spontaneous streptomycin-dependent mutants (StrDA) were isolated from Escherichia coli C600. On C600 StrD, the lytic growth of phage lambda Nam and lambda cI857 was inhibited. After E. coli lysogenic strain 1.1485 (lambda cI857) mutated to StrDA, induction of lambda was decreased greatly. On StrDA of E. coli strains C600 and 1.1485 (lambda cI857), the plating efficiencies and burst sizes of phage T4 and T7 remained normal. Since StrDA is a mutation in the structural gene for ribosomal protein S12, the results obtained in the present study suggest that ribosomes of the StrDA mutants inhibit the lytic growth of lambda phage. The possibility that StrDA ribosomes inhibit the expression of lambda N gene is discussed based on the comparison of the genetic background of lambda cI857 and lambda Nam.

Methylated DNA-binding protein from human placenta recognizes specific methylated sites on several prokaryotic DNAs

Methylated DNA-binding protein (MDBP) from human placenta recognizes specific DNA sequences containing 5-methylcytosine (m5C) residues. Comparisons of binding of various prokaryotic DNAs to MDBP indicate that m5CpG is present in the recognition sites for this protein but is only part of the recognition sequence. Specific binding to MDBP was observed for bacteriophage XP12 DNA, which naturally contains approximately 1/3 of its residues as m5C, and for Micrococcus luteus DNA, M13mp8 replicative form (RF) DNA, and pBR322 when these three DNAs were methylated at CpG sites by human DNA methyltransferase. Five DNA regions binding to MDBP have been localized by DNase I footprinting or restriction mapping in methylated pBR322 and M13mp8 RF DNAs. A comparison of their sequences reveals a common 5'-m5CGRm5CG-3' element or closely related sequence in which one of the m5C residues may be replaced by a T. In addition to this motif, one upstream and one downstream m5CpG as well as other common residues over an approximately 20-bp long region may be recognized by MDBP.