Differential immunohistochemical localization of xanthine oxidase in normal and neoplastic human breast epithelium

Xanthine oxidase (XO) and xanthine dehydrogenase (XDH) are alternate enzymatic forms of the XO/XDH protein that catalyzes the oxidation of hypoxanthine to xanthine, and xanthine to uric acid, and in the process XO/XDH generates reactive oxygen species (ROS) such as superoxide, hydrogen peroxide, and hydroxyl radicals. We hypothesize that XO/XDH, which is expressed in mammary epithelium, contributes to the development of breast cancers by virtue of its ability to generate genotoxic ROS. In this study, we produced human XO/XDH protein at high levels in Spodoptera frugiperda (Sf9) insect cells using the baculovirus vector to confirm the specificity of antibodies used for immunostaining of human breast tissues. Immunoblot analysis demonstrated that the full length 143 kDa polypeptide was partially processed into a 87 kDa and 59 kDa fragments. The overexpressed XO/XDH protein was identified in the cytoplasm of insect cells by immunofluorescence staining. Using these antibodies we analyzed normal and neoplastic breast epithelium for the presence of XO/XDH. Immunohistochemical analysis of normal human breast revealed the presence of XO/XDH in the cytoplasm of epithelium lining terminal ducts. The intensity of XO/XDH staining was markedly enhanced in alveolar epithelium of lactating mammary lobules. In contrast, no immunohistochemically detectable XO/XDH was observed in intraductal in situ carcinomas and in invasive carcinomas of the breast. Further studies are necessary to confirm the utility of the loss of XO/XDH expression as a marker for neoplastic change in the breast and investigate the functional role of this enzyme in the pathogenesis of breast cancer.

Purine metabolism and control of cell proliferation

Exposure of normal lymphocytes to phytohaemagglutinin or other lectin mitogens results in increased concentrations of 5-phosphoribosyl-1-pyrophosphate (PP-ribose-P) within minutes. Subsequently, synthesis of purine nucleotides by both the de novo and the salvage pathways is facilitated. This change is prevented by proliferation-inhibiting concentrations of exogenous adenosine. The capacity of lymphocytes to metabolize both adenine and adenosine is increased several-fold by incubation with phytohaemagglutinin but the specific activities of the respective first-step enzymes are not significantly altered. These results suggest that the relatively low quantity of PP-ribose-P available in normal lymphocytes is a major factor limiting the synthesis of purine nucleotides and may be important for the maintenance of the quiescent state. Increased availability of PP-ribose-P may also be associated with proliferative activation of fibroblast-like cells: chick embryo fibroblast cultures released from density-dependent inhibition of growth by insulin, trypsin or serum rapidly increase the rate of adenine incorporation into nucleotides. Chick embryo fibroblasts transformed by Rous sarcoma virus, but not cells infected with the respective non-transforming leukosis virus, show PP-ribose-P concentrations higher than those observed in normal cells.

Manganese superoxide dismutase in human pleural mesothelioma cell lines

Mesothelioma is a malignant pleural or intraperitoneal tumor attributable to asbestos exposure in more than 80% of the cases. Manganese superoxide dismutase (MnSOD), a mitochondrial superoxide radical scavenging enzyme, is low in most tumors but is known to be induced by asbestos fibers and certain cytokines. Induction of MnSOD may be associated in asbestos-related pulmonary diseases in vivo. We investigated here MnSOD specific activity and MnSOD mRNA level using healthy human lung tissue, SV40-transformed human pleural mesothelial cells (Met5A), and six human malignant mesothelioma cell line cells. Total SOD (CuZnSOD + MnSOD) and MnSOD activities were 20.0 +/- 4.8 U/mg protein and 3.2 +/- 1.2 U/mg protein in healthy human lung tissue, and 25.6 +/- 10.7 U/mg and 3.8 +/- 1.0 U/mg in Met5A cells, respectively. In four mesothelioma cell lines MnSOD activity was significantly elevated, the highest activity (30.1 +/- 8.2 U/mg) was almost 10-fold compared to the activity in Met5A cells. The steady state mRNA level of MnSOD was low in Met5A cells and markedly higher in all mesothelioma cell lines roughly in proportion with enzyme activities. Cytotoxicity experiments, which were conducted in four cell lines, indicated that cells containing high MnSOD mRNA level and activity were resistant to the mitochondrial superoxide-producing agent menadione. In conclusion, our results suggest that human mesothelioma may express high levels of MnSOD, which is associated with high oxidant resistance of these cells.

Catalase and glutathione reductase protection of human alveolar macrophages during oxidant exposure in vitro

Because alveolar macrophages generate and release reactive oxygen metabolites but also contain antioxidative enzymes, they have the potential of either damaging or protecting tissues. We investigated the relative role of the hydrogen peroxide (H2O2)-scavenging antioxidative enzymes in H2O2 disposal and cell protection using freshly isolated (5 h ex vivo) and overnight (24 h ex vivo) cultured human alveolar macrophages. Cell protection was assessed on the basis of maintenance of cellular high-energy phosphates, leakage of intact nucleotides into the extracellular medium, and appearance of the nucleotide catabolic products xanthine, hypoxanthine, and uric acid. To investigate the relative importance of catalase and the glutathione redox cycle, the experiments were conducted in cells pretreated with amino-triazole (ATZ) to inactivate catalase or with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) to inactivate glutathione reductase. Catalase, glutathione peroxidase, and glutathione reductase activities did not change significantly during overnight culture of the cells. Both freshly isolated and cultured cells consumed exogenous H2O2 mainly by the catalase-dependent pathway. When the cells were exposed to H2O2 (100 microM), catalase and the glutathione redox cycle equally participated in maintaining cellular high-energy nucleotides. However, when cultured cells were exposed to formylated peptide (FMLP) (10(-7) M), the glutathione redox cycle was responsible for the maintenance of high-energy nucleotides. Furthermore, in both exposures, the glutathione redox cycle was more important in maintaining cell membrane integrity and preventing nucleotide leakage from the cells. Immunocytochemical labeling showed that catalase was primarily localized in the peroxisomal compartment of these cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Chlamydia trachomatis seropositivity during pregnancy is associated with perinatal complications

Sera from the mothers of all children from the greater Helsinki area who were treated in the Neonatal Intensive Care Unit (NICU) of Children's Hospital (University of Helsinki) during a 22-month period were studied serologically, and antibody levels for mothers were compared with those for matched controls. IgM to Chlamydia trachomatis serotype GFK was detected more often in sera from mothers with children in the NICU than in that from controls; IgM was detected in sera from 39 of 264 mothers vs. 15 of 274 controls (P < .001; two-tailed test). The gestational age of children born to mothers in the IgM-seropositive group was 32.4 weeks whereas that of children born to mothers in the IgG/IgM-seronegative group was 34.3 weeks (all children were treated in the NICU). The frequency of signs of maternal infection (i.e., fever and vaginal discharge), the frequency of meconium-stained amniotic fluid, the frequency of chorioamnionitis, and the mortality rate were higher in the IgM-seropositive group than in the IgM-seronegative group; pneumonia, atelectasis, and pneumothorax occurred more frequently in the seronegative group. Thus, in terms of birth weight and perinatal infections, the outcome was better for children whose mothers did not have antibodies to C. trachomatis.

N-terminal propeptide of type III collagen in tracheal fluid and serum in preterm infants at risk for bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a common pulmonary complication in preterm infants that leads to fibrosis of the bronchoalveolar walls and often to severe clinical consequences. Type III collagen is deposited early in progressive fibrosis. Because the N-terminal propeptide of type III collagen (PIIINP), a by-product of type III collagen synthesis, reflects the degree of pulmonary fibrosis in adults, we hypothesized that PIIINP in tracheal aspirates and/or serum may be a useful early marker of developing BPD in neonates. We serially measured PIIINP in tracheal fluid and serum samples during the first weeks of life in 41 consecutive respirator-treated preterm infants (mean birth weight 1067 g, mean gestational age 28.3 wk). Eight of the infants died and 22 infants fulfilled the criteria for BPD at age 28 d. The mean level of PIIINP decreased with advancing postnatal age in tracheal fluid but not in serum. The mean tracheal fluid PIIINP during d 1 and 2 of life, respectively, was 175 and 200 ng/mg protein in infants who were still in a respirator at age 28 d (n = 13), 122 and 97 ng/mg protein in those who were weaned earlier (n = 20), and 50 and 30 ng/mg protein in those who died before age 28 d (n = 8). These differences are not statistically significant, and the variability of the values was large. The PIIINP concentrations in tracheal aspirates of infants subsequently developing BPD did not differ from those without BPD. Neither did the levels correlate with the degree of BPD or radiologically defined fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of betamethasone and ritodrine on the fetal secretion of lung surfactant

Beta-sympathomimetic drugs and glucocorticoid agents are given in preterm labor to prevent severe consequences of prematurity. It is unclear whether beta-sympathomimetics accelerate lung maturation, or whether they only tend to delay preterm delivery. We have evaluated the effects of betamethasone and ritodrine in rabbits on alveolar lavage phospholipids in premature rabbits, a mean of 28.7 days from conception. Betamethasone given to 26-day-old fetuses increased the surfactant phospholipids, phosphatidylinositol and disaturated phosphatidylcholine; increased disaturated phosphatidylcholine/sphingomyelin ratio, and phosphatidylinositol (percent of phospholipids), as compared to untreated littermates, or to saline treated controls. A low dose of ritodrine given to the pregnant doe, and a high dose given at premature birth had no detectable effects on alveolar lavage phospholipids. However, a high dose of ritodrine given one day before the delivery to the fetus and at premature birth decreased the disaturated phosphatidylcholine/sphingomyelin ratio and phosphatidylinositol in alveolar lavage. While glucocorticoid administration increases the synthesis and secretion of surfactant phospholipids, a high dose of a betasympathomimetic drug may decrease the surfactant. However, spontaneous premature labor is associated with accelerated lung maturation, and accordingly the present results do not contradict the use of a low dosage of betasympathomimetic drug to delay preterm delivery.

Haemoglobin AIc predicts the perinatal outcome in insulin-dependent diabetic pregnancies

Haemoglobin AIc (Hb AIc) was measured in 112 insulin-dependent diabetic pregnancies on an average 4.7 times. Hb AIc was high in early pregnancy in all three patients with severe fetal malformations. There were six pregnancies with a perinatal death. The maximum Hb AIc values were significantly higher in the second trimester (p less than 0.001) in these pregnancies than in the other diabetic pregnancies. When neonatal hypoglycaemia was present, the mean maternal Hb AIc was significantly higher in the second (p less than 0.005) and third (p less than 0.02) trimesters of pregnancy than in the group without neonatal hypoglycaemia. In the group with neonatal hyperbilirubinaemia the mean maternal Hb AIc was significantly higher in the third trimester (p less than 0.02) than in the group with no neonatal hyperbilirubinaemia. The results suggest that poor metabolic control of maternal diabetes during the second trimester is associated with a clearly increased risk of perinatal death and during the second and third trimesters with metabolic derangements in the neonatal period. The results also indicate that Hb AIc could be used to detect the pregnant diabetics at special risk.

Enzymatic diagnosis and carrier detection of aspartylglucosaminuria using blood samples

The activity of the glycoprotein degrading lysosomal hydrolase, 4-L-aspartylglycosylamine amido hydrolase (AAD Gase, EC.3.5.1.26), was measured in plasma, buffy coat leukocytes, and separated lymphocytes (Ficoll separation) from 16 patients with aspartylglucosaminuria (AGU), 29 obligate heterozygotes, and 30 control subjects. In lymphocytes the AGU patients had unmeasurable or minimal AAD Gase activity with a mean of 3.9 U. The obligate heterozygotes showed AAD Gase activities ranging from 5 to 69 U with a mean of 34.1 U. Enzyme activities in the control group ranged from 91 to 243 U with a mean of 127.9 U, and were clearly separated from the values of the heterozygotes. In leukocytes the AGU patients had unmeasurable enzyme activity and obligate heterozygotes had enzyme levels closely similar to those in the lymphocytes from the same individuals. The AAD Gase activity in the leukocytes of the control group displayed a much wider variation than in the lymphocytes, ranging from 22 to 132 U with a mean of 70.7 U. In plasma the AGU patients had undetectable AAD Gase activity. The mean enzyme level of obligate heterozygotes was 72.2 U and that of control individuals 107.2 U, but the overlap between the groups was extensive. The results indicate that homozygous deficiency of AAD Gase, i.e., aspartylglucosaminuria can be reliably diagnosed using plasma, leukocytes, or separated lymphocytes. For carrier detection only separated lymphocytes allow a satisfactory differentiation between heterozygous and normal individuals. A group of 31 siblings of verified AGU cases and 11 children of identified carriers, whose spouses had normal AAD Gase activity, were investigated using the lymphocyte assay. The observed and expected frequencies (on the basis of Mendelian probabilities) were closely similar, suggesting that the lymphocyte assay can be used reliably for carrier detection.

Prenatal diagnosis and fetal pathology of I-cell disease (mucolipidosis type II)

Increased activity of several lysosomal hydrolases was demonstrated in amniotic fluid from a fifteenth week pregnancy in which the fetus had I-cell disease. Cultured cells from amniotic fluid had a decreased activity of the same enzymes. The diagnosis of I-cell disease was later confirmed by enzyme assays in cell cultures of fetal skin and by morphologic studies of several tissues from the aborted fetus. Electron microscopic studies of the fetal tissues and cultured fibroblasts had large numbers of typical inclusions of I-cell disease, thus substantiating the diagnosis and intrauterine manifestation of the disease. The results indicate that prenatal diagnosis of I-cell disease is possible with enzyme assays of amniotic fluid and in cultures of fetal cells from the fluid. Enzyme studies of amniotic fluid can provide a preliminary diagnosis within a few hours, but it is suggested that the definitive diagnosis should be based on assays in cultured cells from amniotic fluid.