Methylthioadenosine phosphorylase cDNA transfection alters sensitivity to depletion of purine and methionine in A549 lung cancer cells

Methylthioadenosine phosphorylase (MTAP), an enzyme involved in purine and methionine metabolism, is present in all normal tissues but is frequently deficient in a variety of cancers. It has been suggested that this metabolic difference between normal and cancer cells may be exploited to selectively treat MTAP-negative cancers by inhibiting de novo purine synthesis and by depleting L-methionine. However, these therapeutic strategies have only been tested in naturally occurring MTAP-positive and -negative cell lines, which might have additional genetic alterations that affect chemotherapeutic sensitivity. Therefore, it is of importance to examine the feasibility of enzyme-selective treatment using paired cell lines that have an identical genotype except for MTAP status. MTAP-negative A549 lung cancer cells were transfected with eukaryotic expression vectors encoding MTAP cDNA in sense and antisense orientations. The resultant stable transfectomas were treated with inhibitors of de novo purine synthesis such as methotrexate, 5,10-dideazatetrahydrofolate, and L-alanosine and by methionine depletion. The A549 cells transfected with an antisense construct (antisense transfectoma) expressed no MTAP protein and were more sensitive to both purine and methionine depletion than were cells expressing MTAP protein (sense transfectoma). Methylthioadenosine was able to completely rescue the sense transfectoma but not the antisense transfectoma from growth inhibition by depletion of purine and methionine. These results prove that MTAP deficiency contributes directly to the sensitivity of cancer cells to purine or methionine depletion. Inhibition of de novo purine synthesis, combined with methionine depletion in the presence of methylthioadenosine, is a highly selective treatment for MTAP-negative cancers.

[Estimation and control measures for environmental tobacco smoke in an office]

The aim of this study is to evaluate the air pollution due to smoking in an office where no smoking control measures have been adopted. The concentration of suspended particulates (SP) at 8 points in this office were measured and the change of SP concentrations at 3 points were recorded for 24 hours. The results show that the main source of SP is tobacco smoke in the office. Smoking control measures should be promoted in such offices where smokers and non-smokers work together. The effectiveness of a ventilation system and practical smoking control measures are discussed.

Enteric pathogens in severe forms of acute gastroenteritis in Ghanaian children

Diarrheal disease is the major cause of childhood morbidity in developing countries. Although malnutrition is known as a risk factor for severe gastroenteritis, the role of enteric pathogens in the clinical severity is unclear. The present study was conducted in well nourished Ghanaian preschool children during a 3 month period of the rainy season to assess the relationship between enteric pathogens and severe gastroenteritis. Two hundred and twenty-five children with acute gastroenteritis and 64 age-matched control children were prospectively examined for the severity of dehydration and enteric pathogens in their stools. Of the 225 children with gastroenteritis, 69.8% (157/225) had mild dehydration and 30.2% (68/225) had severe dehydration. Bacteria were similarly isolated in stool samples from children with mild and severe dehydration and controls. Rotavirus accounted for 20.6% of children with severe dehydration and was more often isolated in stools from patients with severe dehydration than those from controls. Furthermore, the mixed infections associated with rotavirus and bacteria were more often found in patients with severe dehydration than those with mild dehydration or controls. Parasites were similarly found at low incidences among the three groups. The present study implied that rotavirus was more responsible for severe gastroenteritis than bacteria or parasites. However, factors other than enteric pathogens must be sought in a considerable number of severe cases. A large scale study throughout a year is recommended to obtain more precise information that would reflect the seasonal variation of rotavirus infections.

Favorable effect of transcranial electrostimulation on behavior disorders in elderly patients with dementia: a double-blind study

The efficacy of transcranial electrostimulation for sleep-wake and behavior disorders in elderly patients with dementia was tested in a double-blind study. The subjects were 27 inpatients with multi-infarct dementia (12 males and 15 females, aged 58-86). They were randomly divided into two groups: active treatment (n = 14) and placebo treatment (n = 13). For electrostimulation, a device (HESS-100) was used which delivered repetitive rectangular electric pulses of 6-8 V at increasing frequencies from 6 to 80 Hz, each pulse lasting 0.2 ms and with a root mean square value of 256-530 microA. Electrostimulation was performed for 20 minutes from 10:00 h every morning. The active or placebo treatment was performed for 2 weeks in each group. The electrostimulation was significantly effective in behavior disorders such as wandering or nocturnal delirium, and decreased motivation during the daytime. It was also effective in improving night sleep. Electroencephalograms confirmed increased vigilance levels in the daytime both during and after the treatment.

Relationship between thyroid-stimulating antibodies and thyrotropin-binding inhibitory immunoglobulins years after administration of radioiodine for Graves' disease: retrospective clinical survey

Thyroid-stimulating antibody (TSAb) activity and the TSH-binding inhibitory immunoglobulin (TBII) index were assessed in 158 patients with Graves' disease who had been treated with 131I 6-14 years earlier. Twenty-one patients (13%) were still hyperthyroid, 45 (28%) were euthyroid, 44 (28%) were subclinically hypothyroid, and 48 (30%) were overtly hypothyroid. Positive results were obtained in 10 (48%) of the 21 patients with hyperthyroidism for both TSAb and TBII assays, and in 3 patients (14%) in one of the assays. In contrast, only two (5%) patients with subclinical hypothyroidism and 1 (2%) patient with overt hypothyroidism tested positive in both assays, and 11 (25%) subclinically hypothyroid patients and 15 (31%) overtly hypothyroid patients tested positive in one of the assays. The correlation coefficients between TSAb and TBII were 0.88 (p < 0.01) in hyperthyroid patients, 0.49 (p < 0.01) in euthyroid patients, 0.34 (p < 0.05) in subclinically hypothyroid patients, and 0.12 (p > 0.05) in patients with overt hypothyroidism. Findings indicate the presence of long-term changes in the population of TSH receptor antibodies years after 131I treatment, which may influence thyroid function.

Differential expressions of collagen types IV, III, and I during the development of invasive trophoblasts in rats

We examined the differential expressions of collagen types IV, III and I in the developing feto-maternal placental tissue of pregnant rats by a combination of in situ hybridization and immunohistochemistry. At day 9.5 of gestation, polygonal invasive cytotrophoblasts from the ectoplacental cone, which was modifying the maternal central artery, revealed intensely expressed alpha 1 (IV) and alpha 1 (III) collagen mRNAs. The localization patterns of these translated products, collagen type IV and procollagen type III, were slightly different in the invasive cytotrophoblasts. Collagen type IV densely deposited intracellularly and intercellularly in the maternal central artery and in the thickened basement membranes of the cytotrophoblasts. However, expression of alpha 1 (I) collagen mRnA and procollagen type I was hardly detectable in the cytotrophoblasts. At day 13 of gestation, a high level of alpha 1 (IV) collagen mRNA was expressed in the cytotrophoblastic cell layer (trophospongium) and in the invasive large cytotrophoblasts. A moderate level of alpha 1 (III) collagen mRNA was also expressed mainly in the cytotrophoblasts, while alpha 1 (I) collagen mRNA was expressed at very low levels. Interestingly, procollagen type III failed to show linear immunoreactivity in the subepithelial extracellular matrix beneath the maternal artery with the invasive cytotrophoblasts. Additional quantitative analyses of these type IV, III, and I collagen mRNA levels in in situ hybridization experiments between several cell types also revealed significant differences individually. Electron-microscopic study detected no cross-striated collagen fibers in the thickened basement membrane-like structures adjacent to the invasive cytotrophoblasts. Fibrillar and basement membrane collagen gene expressions, their protein syntheses, and the processing of these procollagens seems to be developmentally regulated in the invasive cytotrophoblasts during the organization of feto-maternal placental tissue. The remodeling of the maternal central artery by the invasive cytotrophoblasts is important for ensuring the adequate blood supply to the developing placenta and fetus.

Characterization of monoclonal antibodies recognizing human merosin and their use in affinity purification of native merosin

Two monoclonal antibodies (MAbs) to human placenta laminin (pl-LAM), 1D8 (IgG1) and 6G5 (IgG2b) were generated and shown by ELISA and immunoblot analysis to recognize only native pl-LAM, but not denatured, reduced pl-LAM or mouse EHS laminin. Intact pl-LAM was easily isolated and purified in large scale from human placenta by 1D8-conjugated affinity chromatography. Electrophoretic analysis of the purified pl-LAM revealed the presence of a major 750-kDa component composed of 320-, 220-, and 200-kDa polypeptides and a minor 800-kDa component composed of 320-, 240-, and 220-kDa polypeptides. Neither molecule had a 400-kDa component corresponding to the A chain. It has already been shown that the 320-kDa polypeptide is identical to the M chain of human merosin (Hori et al. J. Biochem. 1994;116:1212-1219). Electron microscopy revealed that isolated merosin was composed of three short arms and one long arm. By immunohistochemistry, MAbs showed positive staining in human adult kidney and liver. These results indicate that these MAbs recognize only native merosin and can be used to study merosin structure and function by rapid purification of native merosin and by immunohistochemical analysis.

Dystroglycan is a dual receptor for agrin and laminin-2 in Schwann cell membrane

We have shown previously that alpha-dystroglycan with a molecular mass of 120 kDa is a Schwann cell receptor of laminin-2, the endoneurial isoform of laminin comprised of the alpha2, beta1, and gamma1 chains. In this paper, we show that Schwann cell alpha-dystroglycan is also a receptor of agrin, an acetylcholine receptor-aggregating molecule having partial homology to laminin alpha chains in the C terminus. Immunochemical analysis demonstrates that the peripheral nerve isoform of agrin is a 400-kDa component of the endoneurial basal lamina and is co-localized with alpha-dystroglycan surrounding the outermost layer of myelin sheath of peripheral nerve fibers. Blot overlay analysis demonstrates that both endogenous peripheral nerve agrin and laminin-2 bind to Schwann cell alpha-dystroglycan. Recombinant C-terminal fragment of the peripheral nerve isoform of agrin also binds to Schwann cell alpha-dystroglycan, confirming that the binding site for Schwann cell alpha-dystroglycan resides in the C terminus of agrin molecule. Furthermore, the binding of recombinant agrin C-terminal fragment to Schwann cell alpha-dystroglycan competes with that of laminin-2. All together, these results indicate that alpha-dystroglycan is a dual receptor for agrin and laminin-2 in the Schwann cell membrane.

Functional comparison of the myoglobins reconstituted with symmetric deuterohemes

Deuterohemins III and XIII were coupled with apomyoglobin to examine the influence of the modified heme-globin contacts on the functions of the reconstituted holoproteins. Owing to the molecular symmetry of the prosthetic groups, the resultant proteins are free from the heme orientational disorder. The coordination structures of the two reconstituted myoglobins were found to be normal and closely similar to each other. The equilibrium ligand bindings also resembled with each other in both ferric and ferrous states. The results demonstrate that the different local heme-globin contacts affect the structure and function of the reconstituted myoglobins only slightly. The results therefore suggest that the two asymmetric deuteroheme IX isomers, which are inverted about the alpha, gamma-meso carbon axis of the heme, also exhibit very similar functions in myoglobin.

Larvicidal activity of the symbiotic bacterium Xenorhabdus japonicus from the entomopathogenic nematode Steinernema kushidai against Anomala cuprea (Coleoptera:Scarabaeidae)

The entomopathogenicity of the symbiotic bacterium Xenorhabdus japonicus and the nematode Steinernema kushidai was determined. Phase I and II X. japonicus were cultured on an artificial medium and inoculated into the test insect or established into axenic S. kushidai populations. When 100, 1000, or 10,000 bacterial cells of phase I or II were directly injected into the hemocoels of 3rd instar cupreous chafer, Anomala cuprea, both phases in the late log period killed 100% of the larvae by the 2nd day postinoculation. However, both phases in the stationary period were less pathogenic with cupreous chafer mortality < 20 and 80% at 100 and 1000 bacterial cells/ larva, respectively. In vitro studies showed that axenic S. kushidai provided with phase I or II symbionts grew well and produced equal numbers of progeny on a dog food medium, but nematodes with no symbionts did not grow at all. Pig liver extracts added as a dietary supplement to the dog food medium completely restored growth and progeny production of the nematode with no bacterial cells. Studies were conducted with infective juveniles (IJs) harboring phase I or II or no symbionts that were applied against 3rd instar cupreous chafer larvae in compost or injected directly into their hemocoels. In the compost study, IJs harboring phase I killed 100% within 10 days. IJs with phase II or no symbionts caused low mortality of the cupreous chafer larvae at 10 days (< 20%). In the intrahemocoelic injection study, IJs harboring phase I resulted in 60% larval mortality at five nematodes/larva, and as the number of IJs injected increased, significantly higher larval mortality was obtained.

Clonal heterogeneity in human esophageal squamous cell carcinomas on DNA analysis

Cancers are thought to arise through multistep accumulation of somatic mutations in the progeny of a single cell. Multiple mutations may induce molecular intratumor heterogeneity. Therefore, we examined molecular clonal heterogeneity in esophageal squamous cell carcinomas. Twenty-four esophageal squamous cell carcinomas and associated lymph node metastases were examined for microsatellite alterations, and abnormalities of the p53 and transforming growth factor-beta type II receptor (TGF-beta RII) genes. There were eight cases (33%) showing different patterns of loss of heterozygosity in primary tumors and metastatic lymph nodes with microsatellite markers. On the other hand, the abnormalities of p53 were identical in all these cases. No mutation was detected in the simple repeated sequences of the TGF-beta RII gene. These results indicate that molecular clonal heterogeneity exists in esophageal squamous cell carcinomas. Therefore, care is necessary in preoperative genetic diagnosis using biopsy samples.

[Clinical evaluation of sulbactam/cefoperazone for lower respiratory tract infections. Correlation between the efficacy of sulbactam/cefoperazone and beta-lactamase]

The efficacy and safety of sulbactam/cefoperazone (SBT/CPZ) were evaluated in 42 patients with respiratory tract infections, including pneumonia (29 patients) and lower respiratory tract infections (5 patients). Overall clinical efficacy rates (excellent + good) were 79% in pneumonia and 80% in respiratory tract infections in 34 patients evaluated for clinical efficacy. It was excellent that the clinical efficacy rate was 92% in mild and moderate pneumonia. Pathogens isolated from sputa were 31 strains, including 8 strains of Pseudomonas aeruginosa, 7 of Streptococcus pneumoniae, 3 of Staphylococcus aureus and 3 of Haemophilus influenzae. Since the isolates were eradicated in 18 strains, replaced in 3, unchanged in 2 and unknown in 8, the overall eradication rate was 91%. The eradication rates were 89% in beta-lactamase producing strains and 100% in beta-lactamase positive sputum, and excellent or good in 19 (83%) of 23 patients with beta-lactamase negative sputum. The eradication rate was 88% in 5 patients with beta-lactamase positive sputum. One patient experienced a moderate rash. Abnormal laboratory test values were observed in 10 patients (26.3%), but these abnormalities were mild and transient. These results suggested that SBT/CPZ was effective and safe for the treatment of respiratory tract infections caused by beta-lactamase producing as well as beta-lactamase non-producing bacteria.

Deoxycytidine kinase mRNA levels in leukemia cells with competitive polymerase chain reaction assay

Deoxycytidine kinase (dCyd kinase) is important for the phosphorylation of several different nucleoside antimetabolites. To understand the significance of dCyd kinase levels in chemotherapy, dCyd kinase mRNA levels were evaluated in several cells with a quantitative competitive polymerase chain reaction (PCR) assay. dCyd kinase catalytic activity and intracellular ara-CTP production were also compared with the levels of dCyd kinase mRNA. The assay was able to show: (i) that dCyd kinase catalytic activity and dCyd kinase mRNA levels were correlated in cells; (ii) that dCyd kinase mRNA levels were more sensitive in lower levels of 10 amol/micrograms of total RNA; and (iii) in cytosine arabinoside (ara-C)-resistant cells, both dCyd kinase mRNA levels and intracellular ara-CTP levels were lower compared with levels in sensitive cells. The PCR assay for dCyd kinase mRNA could be useful in the selection and monitoring of patients treated with nucleosides that are activated by this enzyme.

A case of prolonged human parvovirus B19 DNA-emia associated with polyclonal B cell activation

The current paper reports an 8 year old girl with arthralgia and polyclonal B cell activation induced by human parvovirus B19 infection (HPV B19). The infection was diagnosed by the presence of the virus genome in sera. The patient presented with transient arthritis in the wrist, ankle joint and neck and elevation of immunoglobulin IgM antibodies to HPV B19 and rubella, antibodies to Mycoplasma and antistreptolysin O but without the typical clinical features of erythema infectiosum. The polyclonal B cell activation was paralleled by the presence of the virus genome of HPV B19 in sera. In some children with arthralgia, it is important to examine the genomes of viruses that may cause arthritis as well as the antibody titers to the viruses.

Characteristics of Epstein-Barr virus-associated gastric carcinoma with lymphoid stroma in Japan

BACKGROUND

Gastric carcinoma with lymphoid stroma (GCLS), known to have a more favorable prognosis than ordinary gastric carcinoma, has been suggested to be closely associated with the Epstein-Barr virus (EBV). However, there are many clinicopathologic problems that remain unsolved.

METHODS

In 21 patients, 26 GCLS lesions and 4 non-GCLS intramucosal adenocarcinomas that developed synchronously or metachronously with GCLS were examined for EBV involvement by in situ hybridization (ISH) and were analyzed clinicopathologically. In addition, nine patients who had advanced gastric carcinoma with massive liver metastases, who showed good response to chemotherapy and had prolonged survival, were examined for the presence or absence of EBV-associated GCLS.

RESULTS

On ISH with EBV-encoded small RNAs, diffuse hybridization signals were noted in 22 (84.6%) of 26 GCLS. Hybridization signals were also noted in all four non-GCLS adenocarcinomas accompanying GCLS. As a result, hybridization signals were noted in nine of ten cancerous lesions in four cases of synchronous multiple cancers and in all five cancerous lesions in two cases of metachronous multiple cancers. Long term survivors with liver metastases included two patients with EBV-associated GCLS.

CONCLUSION

Approximately 84.6% of GCLS were related to EBV. EBV-associated GCLS constitutes one-half of the EBV-infected stomach cancers in our institution. The complete response and long term survival after conventional chemotherapy of two patients with Stage IV GCLS suggests that this form of gastric carcinoma may be especially sensitive to this treatment. The identification of EBV-associated synchronous multicentric cancers of both GCLS and non-GCLS type suggests that EBV infection may be an early event in the induction process of these tumors.

Characteristics of Epstein-Barr virus-associated gastric carcinoma with lymphoid stroma in Japan

BACKGROUND

Gastric carcinoma with lymphoid stroma (GCLS), known to have a more favorable prognosis than ordinary gastric carcinoma, has been suggested to be closely associated with the Epstein-Barr virus (EBV). However, there are many clinicopathologic problems that remain unsolved.

METHODS

In 21 patients, 26 GCLS lesions and 4 non-GCLS intramucosal adenocarcinomas that developed synchronously or metachronously with GCLS were examined for EBV involvement by in situ hybridization (ISH) and were analyzed clinicopathologically. In addition, nine patients who had advanced gastric carcinoma with massive liver metastases, who showed good response to chemotherapy and had prolonged survival, were examined for the presence or absence of EBV-associated GCLS.

RESULTS

On ISH with EBV-encoded small RNAs, diffuse hybridization signals were noted in 22 (84.6%) of 26 GCLS. Hybridization signals were also noted in all four non-GCLS adenocarcinomas accompanying GCLS. As a result, hybridization signals were noted in nine of ten cancerous lesions in four cases of synchronous multiple cancers and in all five cancerous lesions in two cases of metachronous multiple cancers. Long term survivors with liver metastases included two patients with EBV-associated GCLS.

CONCLUSION

Approximately 84.6% of GCLS were related to EBV. EBV-associated GCLS constitutes one-half of the EBV-infected stomach cancers in our institution. The complete response and long term survival after conventional chemotherapy of two patients with Stage IV GCLS suggests that this form of gastric carcinoma may be especially sensitive to this treatment. The identification of EBV-associated synchronous multicentric cancers of both GCLS and non-GCLS type suggests that EBV infection may be an early event in the induction process of these tumors.

Heterogeneous effects of G-CSF and GM-CSF on cell growth and ara-C cytotoxicity in childhood leukemias which express myeloid markers

It is uncertain if acute lymphoblastic leukemia (ALL) cells expressing myeloid makers can respond to granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF). We investigated the effects of G-CSF (0.01 microgram/ml) and GM-CSF (0.01 microgram/ml) on [3H]thymidine (TdR) uptake, and the cytotoxicity of 1-beta-D-arabinofuranosylcytosine (ara-C) in leukemia cells from 17 pediatric patients. ALL cells without myeloid markers did not respond to G-CSF or GM-CSF. On the other hand, these cytokines enhanced the [3H]TdR uptake and cell growth, not only of AML cells but also of ALL cells expressing myeloid antigens. However, G-CSF and GM-CSF did not always enhance the growth inhibitory effect of the cell cycle specific drug ara-C when the cells were co-cultured with the drug. There was no relationship between cell growth and the amount of [3H]TdR incorporation or the intracellular ara-CTP level. These results indicate the heterogeneous effects of G-CSF and GM-CSF on cell growth and ara-C sensitivity in childhood leukemia cells.

On the EEG component waves of multi-infarct dementia seniles

Component waves of EEGs led from the F3-A1, C3-A1, O1-A1, and O2-A2 scalp regions of 24 multi-infarct dementia seniles (MID) patients (ages 58 to 85 years, average 73.3 years) and eight to 19 normal, healthy, adult (NA) subjects were obtained by autoregressive component analysis. Some differences in the component waves were demonstrated between the two groups of subjects. (1) The characteristics of the EEG component waves, including the natural, damping, and resonance frequencies, their power, regularity, etc. were determined, and compared between MID patients and NA subjects. (2) No significant difference was found between male and female patients in the occurrence rate of 11 types of component waves. (3) On the average, the alpha wave frequency was lower in MID patients. (4). Slow alpha waves (7.5 to 9.4 Hz) of MID patients were superior to those of NA subjects, whereas typical alpha waves (9.5 to 11.4 Hz) were inferior to those of NA subjects. (5) The power of alpha waves in the F3-A1 and C3-A1 regions of MID patients was superior to that of NA subjects, whereas the result was reversed in the O1-A1 and O2-A2 regions. However, there was less regularity of alpha waves in all regions among MID patients. (6) The theta wave frequency in all regions was higher in MID patients than in NA subjects. (7) Both the power and regularity of theta waves of MID patients were superior to those of NA subjects in all regions. (8) The average number of delta waves that appeared in the O1-A1 and O2-A2 regions was larger in MID patients than in NA subjects. EEG were led from the F3-A1, C3-A1, O1-A1, and O2-A2 scalp regions of multi-infarct dementia seniles (MID) patients, who had sleep disorders, such as reversed day-time sleep patterns or irregular sleep-wake patterns, frequently accompanied by behavior disorders, such as wandering, violent behavior, and/or delirium. Examination by the method of EEG pattern discrimination revealed some differences in EEG component waves in comparison with normal, healthy, adult (NA) subjects.

K-ras point mutations in cancerous and noncancerous biliary epithelium in patients with pancreaticobiliary maljunction

BACKGROUND

Pancreaticobiliary maljunction (PBM), an anomalous union of the pancreatic duct with the common bile duct, has frequently been shown to be associated with biliary carcinoma. However, the mechanism of carcinogenesis is unknown.

METHODS

Mutations of the K-ras oncogene were examined in cancerous and noncancerous biliary tract epithelium of 20 patients with PBM by an extraction of DNA from surgically resected histologic specimens. DNA was analyzed by a polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) method and direct sequencing.

RESULTS

An abnormally mobilized DNA band was detected not only in cancerous epithelium but also in hyperplastic, metaplastic, and inflammatory epithelium of the gallbladder and/or common bile duct in patients with PBM. Among the biliary epithelium of patients with PBM, point mutation of K-ras oncogenes were detected in 4 of 5 (80%) cancerous epithelium, 7 of 12 (58%) hyperplastic and metaplastic epithelium, and 8 of 18 (44%) inflammatory epithelium, whereas no point mutation of the K-ras oncogene was detected in the gallbladder epithelium in 3 control patients without PBM. Direct sequence analysis of the K-ras oncogene revealed the mutation at codon 12 substituting the wild-type glycine (GGT) for aspartic acid (GAT) in all cancerous lesions of patients with PBM. Simultaneous two-point mutations from the wild-type glycine (GGC) to arginine (CGC) at codon 13 associated with the mutation at codon 12 were also found in one case of gallbladder carcinoma and one case of bile duct carcinoma.

CONCLUSIONS

K-ras gene mutation is involved in the carcinogenesis of biliary tract epithelium in patients with PBM, and appears to be a high risk factor for carcinogenesis of the biliary tract.

Oxygen equilibrium properties of chromium (III)-iron (II) hybrid hemoglobins

Cr(III)-Fe(II) hybrid hemoglobins, alpha 2(Cr) beta 2(Fe) and alpha 2(Fe) beta 2(Cr), in which hemes in either the alpha- or beta-subunits were substituted with chromium(III) protoporphyrin IX (Cr(III)(PPIX), were prepared and characterized by oxygen equilibrium measurements. Because Cr(III)PPIX binds neither oxygen molecules nor carbon monoxide, the oxygen equilibrium properties of Fe(II) subunits within these hybrids can be analyzed by a two-step oxygen equilibrium scheme. The oxygen equilibrium constants for both hybrids at the second oxygenation step agree with those for human adult hemoglobin at the last oxygenation step (at pH 6.5-8.4 with an without inositol hexaphosphate at 25 degrees C). The similarity between the effects of the Cr(III)PPIX and each subunits' oxygeme on the oxygen equilibrium properties of the counterpart Fe(II) subunits within hemoglobin indicate the utility of Cr(III)PPIX as a model for a permanently oxygenated heme within the hemoglobin molecule. We found that Cr(III)-Fe(II) hybrid hemoglobins have several advantages over cyanomet valency hybrid hemoglobins, which have been frequently used as a model system for partially oxygenated hemoglobins. In contrast to cyanomet heme, Cr(III)PPIX within hemoglobin is not subject to reduction with dithionite or enzymatic reduction systems. Therefore, we could obtain more accurate and reasonable oxygen equilibrium curves of Cr(III)-Fe(II) hybrids in the presence of an enzymatic reduction system, and we could obtain single crystals of deoxy-alpha 2(Cr) beta 2(Fe) when grown in low salt solution in the presence of polyethylene glycol 1000 and 50 mM dithionite.

Characteristics of Epstein-Barr virus-associated gastric carcinoma with lymphoid stroma in Japan

BACKGROUND

Gastric carcinoma with lymphoid stroma (GCLS), known to have a more favorable prognosis than ordinary gastric carcinoma, has been suggested to be closely associated with the Epstein-Barr virus (EBV). However, there are many clinicopathologic problems that remain unsolved.

METHODS

In 21 patients, 26 GCLS lesions and 4 non-GCLS intramucosal adenocarcinomas that developed synchronously or metachronously with GCLS were examined for EBV involvement by in situ hybridization (ISH) and were analyzed clinicopathologically. In addition, nine patients who had advanced gastric carcinoma with massive liver metastases, who showed good response to chemotherapy and had prolonged survival, were examined for the presence or absence of EBV-associated GCLS.

RESULTS

On ISH with EBV-encoded small RNAs, diffuse hybridization signals were noted in 22 (84.6%) of 26 GCLS. Hybridization signals were also noted in all four non-GCLS adenocarcinomas accompanying GCLS. As a result, hybridization signals were noted in nine of ten cancerous lesions in four cases of synchronous multiple cancers and in all five cancerous lesions in two cases of metachronous multiple cancers. Long term survivors with liver metastases included two patients with EBV-associated GCLS.

CONCLUSION

Approximately 84.6% of GCLS were related to EBV. EBV-associated GCLS constitutes one-half of the EBV-infected stomach cancers in our institution. The complete response and long term survival after conventional chemotherapy of two patients with Stage IV GCLS suggests that this form of gastric carcinoma may be especially sensitive to this treatment. The identification of EBV-associated synchronous multicentric cancers of both GCLS and non-GCLS type suggests that EBV infection may be an early event in the induction process of these tumors.

Effects of thyroid hormone on carbonic anhydrase I concentration in human erythroid burst-forming unit-derived cells

Individuals with hyperthyroidism exhibit red blood cell concentrations of carbonic anhydrase I (CAI) that reflect the integrated serum thyroid hormone concentration over the preceding few months. Furthermore, T3, at a physiological free concentration, decreases the CAI concentration in human erythroleukemic YN-1 cells. The effect of T3 on CAI concentration in burst-forming unit-erythroid (BFU-E)- derived cells, obtained by culturing peripheral blood mononuclear cells with various cytokines, including erythropoietin, has now been investigated. BFU-E-derived cells contained a high concentration of CAI (mean +/- SE, 4.8 +/- 0.8 x 10(-12) mol/10(6) cells; n = 8). The CAI in BFU-E-derived cells was immunologically identical to that present in mature red blood cells. T3 decreased the CAI concentration in BFU-E-derived cells in a dose-dependent manner (28%, 47% and 75% decreases at 3 x 10(-10), 1 x 10(-9), and 3 x 10(-9) mol/liter T3, respectively). These results suggest that BFU-E-derived cells may be used to study the effect of T3 on human red blood cell CAI. This system may prove useful in the tissue diagnosis of resistance to thyroid hormone.

Gene cloning and characterization of Pseudomonas putida L-methionine-alpha-deamino-gamma-mercaptomethane-lyase

Methionine dependency has been reported in cancer cell lines and primary tumors. Thus, L-methionine deprivation might have potential value for the treatment of human cancers with a methionine requirement. L-Methionine-alpha-deamino-gamma-mercaptomethane-lyase has been reported to decrease plasma methionine levels and to inhibit tumor growth in experimental animals but has not been studied extensively because sufficient homogeneous enzyme was not available. In this study, we cloned the L-methioninase gene from Pseudomonas putida and isolated pure and abundant recombinant enzyme. Both L-methionine and L-cysteine in culture medium were completely degraded by 1 unit/ml purified enzyme. Two hundred and fifty units/kg L-methioninase administered i.v. to mice yielded 0.7 unit/ml of plasma concentration and lowered total plasma sulfur-containing amino acids by more than 75%. Although sensitivity to enzymatic methionine depletion differed among cell lines, leukemia cell lines were generally more sensitive than solid tumor cell lines. The availability of pure recombinant L-methioninase will allow in vivo studies on the antitumor activity and the potential toxicity of enzymatic methionine depletion.