Detection of estrogen receptor alpha, carbonic anhydrase II and tartrate-resistant acid phosphatase mRNAs in putative mononuclear osteoclast precursor cells of neonatal rats by fluorescence in situ hybridization

Increasing evidence suggests that estrogen deficiency in women promotes the expansion of populations of bone marrow cells that differentiate into osteoclasts under the influence of osteotropic hormones and local factors. A progressive cytoplasmic accumulation of osteoclastic bone resorbing enzymes, such as tartrate-resistant acid phosphatase (TRACP) and carbonic anhydrase II (CA II), characterizes osteoclast differentiation. To evaluate the possibility that estrogen may have a direct effect on osteoclast precursor cells, we investigated the mRNA levels of estrogen receptor a (ERa), TRACP and CA II genes in neonatal rat bone imprints by fluorescence in situ hybridization and confocal microscopy. Morphological assessment of bone imprints has shown that the putative mononuclear osteoclast precursor cells (MOPC) display strongly basophilic cytoplasm and a low nuclear/cytoplasmic ratio, while some of these cells possess pale-staining ruffled border regions similar to those observed in osteoclasts. Both CA II and TRACP mRNAs were detected in putative MOPC as well as multinuclear osteoclasts. The gene transcripts were mainly located in the cytoplasm of these cells. To determine whether these putative MOPC possess ER mRNA, a 637 base pair antisense ER riboprobe was used. The results indicated that MOPC which show TRACP reactivity express high levels of ER gene transcripts in their cytoplasm. In contrast, only a few multinuclear osteoclasts in the bone imprints possessed ER gene transcripts. Interestingly, the levels of ER mRNA in these multinuclear osteoclasts were very low compared with those in the putative MOPC. Treatment with RNase prior to hybridization resulted in a significant loss of signal in these cells. The results of these studies suggest that estrogen may have a direct role in modulating the recruitment of osteoclast precursor cells during osteoclastogenesis.

Osteoclasts from human giant cell tumors of bone lack estrogen receptors

Although estrogen is important in human skeletal homeostasis, the major target cell in bone is unknown. Estrogen receptors (ER) have been demonstrated in osteoblasts and bone marrow stromal cells, but their presence in osteoclasts remains controversial because completely pure preparations have not been available. We have examined expression of ER-alpha and ER-beta messenger RNA (mRNA) by RT-PCR in samples from human giant cell tumor of bone (GCT), including: whole tumor, cultured mononuclear cells, and a pure osteoclast population obtained by microisolation. Whole tumor expressed both ER-alpha and calcitonin receptor (CTR) mRNA and apparently lower levels of ER-beta mRNA. Passaged cultures of tumor mononuclear stromal cells also expressed ER-alpha and low ER-beta but not CTR mRNA. In pure preparations of microisolated osteoclasts, expression of ER-alpha or ER-beta mRNA was not detected, whereas expression of CTR mRNA was readily identified. Microisolated GCT mononuclear cells expressed ER-alpha, but no detectable CTR mRNA. Fluorescence in situ hybridization (FISH) using an ER-alpha riboprobe demonstrated strong signal in the mononuclear cells but multinucleated osteoclasts showed no detectable signal. In contrast, CTR mRNA was detected in multinucleated osteoclasts but not in stromal-like tumor cells by FISH. 17Beta-estradiol consistently showed no effect on bone resorbing activity of osteoclasts from GCT cultured on cortical bone, although calcitonin was a potent inhibitor. These findings indicate that significant expression of ER does not occur in osteoclasts derived from human GCT and suggest that estrogen effects are mediated by other cells of the bone environment.

Chronic exposure of neonatal cardiac myocytes to hydrogen peroxide enhances the expression of catalase

The adaptive response of antioxidant enzymes to oxidative stress in the heart has not been investigated. Because H2O2 is considered to play a major role in reperfusion injury to the heart, this study was undertaken to examine if H2O2 alters the expression of these enzymes in the rat neonatal myocytes. H2O2 was continuously generated by the addition of glucose oxidase to the culture medium. Both the activity and the mRNA for catalase were increased following incubation of neonatal myocytes with non-toxic concentrations of glucose oxidase. The induction of mRNA preceded the enhancement of activity, and both remained elevated after 24 h incubation. Nuclear run-on assay indicated that the transcriptional rate for catalase mRNA was increased. The same treatment did not alter the activities for total superoxide dismutase and Se-glutathione peroxidase. The results suggest that H2O2-induced expression of catalase was in part due to transcriptional activation. It further implies that the induction of catalase may play an important role in protecting hearts from ischemic/reperfusion injury.

Partial inhibition of Na+/K+-ATPase by ouabain induces the Ca2+-dependent expressions of early-response genes in cardiac myocytes

Exposure of neonatal rat cardiac myocytes to ouabain concentrations that caused partial inhibition of Na+/K+-ATPase but no loss of viability, increased c-fos and c-jun mRNAs and the transcription factor AP-1. The increased mRNAs were proportional to the extent of inhibition of Na+/K+-ATPase and the resulting rise in steady state intracellular Ca2+ concentration. The rapid and sustained increase of c-fos mRNA was shown to be due to increased transcriptional rate. Induction of c-fos by ouabain was prevented when either extracellular or intracellular Ca2+ was lowered and was attenuated by pretreatment of myocytes with a phorbol ester under conditions known to down-regulate protein kinase C. Exposure to ouabain for 24-48 h also increased total transcriptional activity and protein content of myocytes. The findings suggest that the same signal responsible for the positive inotropic action of ouabain, i.e. net influx of Ca2+ caused by partial inhibition of Na+/K+-ATPase, also initiates the rapid protein kinase C-dependent inductions of the early-response genes, the subsequent regulations of other cardiac genes by the resulting transcription factors, and stimulation of myocyte growth. Whether these hitherto unrecognized effects of cardiac glycosides are obtained in the intact heart and their relevance to the therapeutic uses of these drugs remain to be determined.

Activation of Na+/K(+)-ATPase by fatty acids, acylglycerols, and related amphiphiles: structure-activity relationship

A number of fatty acids and derivatives have been shown to activate Na+/K(+)-ATPase when ATP is suboptimal. To explore the relation of the structures of these amphiphiles to enzyme activation, the effects of varying amphiphile concentrations on the activity of the highly purified kidney Na+/K(+)-ATPase at 50 microM ATP were determined. Among fatty acids, efficacy (maximal level of activation) and potency were found to be dependent, in different ways, on chain length and unsaturation. Compared to fatty acids, the corresponding alcohols had lower efficacies. Methyl esters of fatty acids inhibited, but CoA esters and monoacyl esters of glycerol activated the enzyme. Relation between chain length and potency among CoA esters and monoacylglycerols was the same as that observed with acids. Diacylglycerols did not activate, but they antagonized the effects of the activator amphiphiles. The substantial specificities of the amphiphile effects support the hypothesis that these ligands bind to a distinct amphipathic peptide segment of the intracellular central loop of the alpha-subunit to regulate ATP binding to the enzyme. The findings also suggest that direct effects of the changing intracellular levels of fatty acids and derivatives on Na+/K(+)-ATPase should be considered as a possible mechanism for the regulation of its function in the intact cell.

Dual phenotypic expression of hepatocytes and bile ductular markers in developing and preneoplastic rat liver

This study supports the existence of a pluripotent liver stem cell population which has the potential to differentiate into hepatocytes and bile ductular cells. We compared the expression of hepatocyte-specific and bile ductular-specific markers in fetal and preneoplastic rat liver. L-pyruvate kinase (L-PK) and alpha glutathione S-transferase (GST) were used as adult hepatocyte-specific markers, while cytokeratin 19 (CK19) was used as a bile ductular-specific marker. pi GST and M2-pyruvate kinase (M2-PK), which are fetal hepatocyte-specific and expressed at high levels in the oval and duct-like cells, were also used. We characterized fetal liver derived from 13-21 days of gestation (E13-E21). pi GST was detected in the E18 hepatoblasts, which form the intrahepatic bile ducts, while CK19 was detected at E19. Some of these cells express alpha GST and L-PK from E19 to E21. Oval, duct-like and bile ductular cells in rats treated with a choline-deficient diet containing 0.07% ethionine (CDE diet) for up to 8 weeks were characterized by double immunocytochemistry. L-PK and alpha GST are absent from bile ductular cells in the normal adult liver and up to 3 weeks of CDE treatment. After 4-5 weeks on CDE treatment, the majority of bile ductular cells express L-PK, while at 6 weeks some co-express L-PK and alpha GST. There are two populations of oval cells, a major population expressing only the fetal hepatocyte markers, while a minor population expresses the fetal hepatocyte, adult hepatocyte and bile ductular markers. There are at least three different duct-like cell populations which co-express different markers and have characteristics of fetal hepatocytes at sequential stages of differentiation. One population co-expresses pi GST and M2-PK and is similar to fetal hepatocytes derived from E13-E14 fetuses. The second expresses the two fetal markers and L-PK, and this reflects characteristics of E15 hepatocytes. The third expresses pi GST, M2-PK, L-PK and alpha GST which is characteristic of E16-E19 hepatocytes. Upon withdrawal of the CDE diet, autoradiography using tritiated thymidine shows that oval and duct-like cells differentiate into hepatocytes. This study demonstrates that oval and duct-like cells express both hepatocytic and bile ductular markers, and have the capacity to differentiate into hepatocytes, characteristics similar to hepatoblasts in the developing rat liver.

Synchronous bilateral carcinoma of the ureter in association with unilateral incomplete duplication of the ureter

A case of bilateral synchronous ureteral tumors, in association with a unilateral incomplete duplication of ureter, is presented. This patient underwent right nephroureterectomy with removal of a cuff of bladder, partial resection of left ureter, and ileal loop interposition between renal pelvis and bladder. Followup showed no recurrence in the residual urinary tract 2-years postoperatively.

Antioxidant enzyme gene transcription in copper-deficient rat liver

Antioxidant enzymes, Cu/Zn- and Mn-superoxide dismutase, catalase, and glutathione peroxidase, constitute an important defense mechanism against cytotoxicity of reactive oxygen species. Copper is essential for the activity of Cu/Zn-superoxide dismutase. Oxidative stress, therefore, is expected in organs of rats fed copper-deficient diet due to reduced Cu/Zn-superoxide dismutase activity. Our previous studies have shown that the expression of antioxidant enzymes was altered in copper-deficient rat liver. The present report was undertaken to study further the transcription of these enzymes in liver nuclei of rats made copper-deficient for 4 weeks. While copper deficiency decreased the copper in liver by about 80%, it did not alter the copper content in liver nuclei. In spite of a 100% elevation in nuclear iron concentration, liver nuclei from copper-deficient rats showed normal appearance. The transcriptional rates for Cu/Zn-superoxide dismutase, glutathione peroxidase, and glyceraldehyde-3-phosphate dehydrogenase were not altered by dietary copper deprivation. In contrast, transcriptional rates for Mn-superoxide dismutase and beta-actin were increased but that for catalase was reduced in the nuclei isolated from the copper-deficient rat liver. These results suggest that oxidative stress, resulting from copper deficiency, differentially modulates the gene transcription for the antioxidant enzymes in rat liver.

Death risk predictors among peritoneal dialysis and hemodialysis patients: a preliminary comparison

Variables associated with survival among 1,522 peritoneal dialysis patients and 16,404 hemodialysis patients who received treatment during 1992 were evaluated. Analysis was performed separately for the treatment types and for the combined patient group. In general, the associates of survival appear similar among patients receiving peritoneal or hemodialysis. Important variables appear related to nutrition, acid-base status (which is related to nutrition), and age.

Effects of doxorubicin on cardiomyocytes with reduced level of superoxide dismutase

Our previous studies have shown that isolated adult rat cardiomyocytes with normal and reduced Cu/Zn SOD activities are equally susceptible to extracellularly generated oxidants (hydrogen peroxide, glucose oxidase/glucose and xanthine oxidase/xanthine systems). In the present study we exposed myocytes with reduced SOD activity to doxorubicin (adriamycin). Cardiotoxicity of doxorubicin has been attributed to the production of superoxide anion inside the cell. Cardiomyocytes with reduced SOD activity, but normal ATP content and viability, were obtained by the treatment of isolated cells with diethyldithiocarbamate (DDC). DDC-treated myocytes were significantly less resistant to doxorubicin than controls. Doxorubicin-stimulated superoxide anion formation, measured by the rate of SOD-inhibitable acetylated cytochrome C reduction, was significantly higher in the cytosolic fraction of DDC-treated cells compared to controls. These results indicate that for isolated cardiac myocytes an essential part of cytotoxicity of doxorubicin can be explained by the formation of superoxide anion and that the level of intracellular SOD activity should be considered as a significant factor for cell protection.

Interactions of phosphorylation and dimerizing domains of the alpha-subunits of Na+/K(+)-ATPase

Chemical cross-linking studies are among a number of experimental approaches that have suggested the functional significance of higher association states of alpha,beta-protomers of Na+/K(+)-ATPase. Formation of the phosphointermediate of the enzyme on Asp369 of the alpha-subunit is known to induce oxidative cross-linking of the alpha-subunits catalyzed by Cu(2+)-phenanthroline. To localize the phosphorylation-induced alpha,alpha-interface, we cleaved alpha at Arg438-Ala439 by controlled proteolysis and exposed the partially cleaved enzyme to the cross-linking reagent. In addition to the alpha,alpha-dimer, two other phosphorylation-induced cross-linked products were obtained. Using gel electrophoretic resolution of the cross-linked 32P-labeled enzyme, N-terminal analyses of the products, and their reactivities with sequence-specific antibodies, the two products were identified as a homodimer of the C-terminal 64-kDa fragment of alpha and a heterodimer of alpha and the 64-kDa peptide. The latter dimer was also obtained when the cross-linked alpha,alpha-dimer was formed first and then subjected to proteolysis. The findings localize the dimerizing domain to the C-terminal side of Ala439 and indicate that intersubunit proximities of dimerizing domains are regulated by phosphorylation-dephosphorylation of Asp369 during the reaction cycle of the enzyme.

Zinc sulphadiazines: novel topical antimicrobial agents for burns

Two new zinc sulphadiazine (Zn(SD)2)-amine complexes, zinc sulphadiazine-methylamine (Zn(SD)2(CH3NH2)2) and zinc sulphadiazine-ethylenediamine (Zn(SD)2(C2H8N2)3.H2O), were prepared and compared with silver sulphadiazine (AgSD). The compounds were readily obtained by reaction of zinc nitrate hexahydrate with sulphadiazine or its salt in methylamine and ethylenediamine, respectively. Structure was established by X-ray crystallography and ultraviolet-visible, infrared and nuclear magnetic resonance spectroscopy. The products were effective, in-vitro, against Gram-positive and Gram-negative bacteria as well as fungus. However, their activity is partially reversed by p-aminobenzoic acid. Further investigations in burned mice revealed that these compounds displayed a potential value in the prevention and treatment of wound healing, and diminution of mortality and weight loss. The toxicity of Zn(SD)2 derivatives was much lower than that of AgSD. The better aqueous solubility and skin permeability may explain the reason for their superiority over AgSD in the efficacy for topical therapy. Zn(SD)2(CH3NH2)2 was consistently more potent and was chosen for further development in clinical uses. The similarity in complexation between Zn(SD)2(CH3NH2)2 and AgSD may be significant to distinguish that from any other Zn(SD)2 derivative in bioactivity.

Role of intracellular SOD in oxidant-induced injury to normal and copper-deficient cardiac myocytes

Previous studies have shown that susceptibilities of hepatocytes and endothelial cells to H2O(2)-induced injury are altered by changes in the intracellular activity of Cu,Zn-containing superoxide dismutase (CuZn-SOD). To evaluate the role of intracellular CuZn-SOD in oxidant-induced injury to rat cardiac myocytes, cells with reduced CuZn-SOD activity but normal ATP content were either isolated from the hearts of adult copper-deficient rats or obtained by treatment of normal isolated adult myocytes with diethyldithiocarbamate. These myocytes and controls with normal CuZn-SOD activity were exposed to either reagent H2O2 or oxidants generated by extracellular glucose oxidase plus glucose or xanthine oxidase plus xanthine. It was shown that myocytes with CuZn-SOD activities reduced by 70-90% were equally susceptible to H2O2 and the two oxidant-generating systems as the control myocytes. The findings suggest that in adult cardiac myocytes, in contrast to the situation in some other cells, intracellular CuZn-SOD may not have a significant defensive role against acute H2O(2)-induced injury. The possibility remains, however, that changes in the activity of this enzyme, e.g., in copper deficiency, may be relevant to the ability of myocytes to cope with chronic oxidative stress resulting from imbalance between intracellular oxygen radical-generating and -scavenging systems.

Functional coupling of phosphorylation and nucleotide binding sites in the proteolytic fragments of Na+/K(+)-ATPase

Cleavage of the alpha-subunit of Na+/K(+)-ATPase by trypsin at Arg438-Ala439 causes enzyme inhibition which has been suggested to be due to altered alignment of phosphorylation site on the 48-kDa N-terminal fragment with nucleotide binding site on the 64-kDa C-terminal fragment. Our aims were to test this hypothesis and to assess the effect of the cleavage on the enzyme's two ATP sites. Na(+)-dependent phosphorylation of the partially cleaved enzyme by ATP showed that K0.5 values of ATP for phosphorylations of intact alpha and 48-kDa peptide were the same (0.4 microM). Unchanged interactions among the residues across the cleavage site were also indicated by data showing that reaction of fluorescein isothiocyanate with the 64-kDa peptide blocked phosphorylation of the 48-kDa peptide by ATP. ATP is known to block the reaction of fluorescein isothiocyanate with the enzyme. Experiments on the partially cleaved enzyme showed that K0.5 of ATP for protection of alpha was 30-60 microM, and the value for the protection of interacting 48-kDa and 64-kDa peptides was 1-3 mM. Evidently, while the cleavage does not affect the high affinity catalytic site, it disrupts the allosteric low affinity ATP site. Experiments on reconstituted preparations showed that the cleavage abolished ATP-dependent Na+/K+ exchange, Pi+ATP-dependent Rb+/Rb+ exchange, ATP-dependent Na+/Na+ exchange, and ADP+ATP-dependent Na+/Na+ exchange activities. Selective disruption of the low affinity ATP site accounts for the inhibitions of all functions involving K+(Rb+), based on the established role of this site in the control of K+ access channels. Cleavage-induced inhibitions of other activities, however, suggest additional roles of the low affinity ATP site in the reaction cycle.

Different oxidant sensitivities of the alpha 1 and alpha 2 isoforms of Na+/K(+)-ATPase expressed in baculovirus-infected insect cells

Inhibition of Na+/K(+)-ATPase by partially reduced oxygen metabolites is an early event in the course of cell injury caused by oxidative stress. We showed before that isoforms of the enzyme obtained from different sources have different oxidant sensitivities. To evaluate the role of tissue-specific impurities in this difference, cDNAs of alpha 1 and alpha 2 isoforms were expressed in Sf-9 insect cells, and the effects of H2O2 on the resulting isolated enzymes were studied. The expressed alpha 2 was significantly more sensitive than alpha 1 to H2O2. These findings, together with our previous data showing different oxidant sensitivities of alpha 1 and alpha 3 in a cardiac enzyme preparation, indicate that differential oxidant sensitivities of Na+/K(+)-ATPase isoforms of various tissues are dictated by the primary sequences of alpha 1, alpha 2, and alpha 3 subunits.

A preliminary exploration of the relationship between tumour necrosis factor (TNF) and monocytic in vitro production of interleukin-1 (IL-1) and internal organ dysfunction in severely burned patients

Biological assays were adopted in this study to examine the changes in serum tumour necrosis factor (TNF) activity and blood monocytic in vitro production of interleukin 1 (IL-1) in 24 severely burned patients. The myocardial and hepatic enzymes (which included aspartate aminotransferase (AST), creatine kinase (CPK), lactate dehydrogenase (LDH), alpha hydroxybutyric dehydrogenase (alpha-HBDH) and alanine amino-transferase (ALT) and some indices of biochemical metabolism (including lactic acid (LA), total protein (TP), albumin (Alb) and colloid osmotic pressure (COP)) were simultaneously measured. The results showed an evident increase in serum TNF activity and a decrease in in vitro production of IL-1 postburn; all the changes in TNF and IL-1 were correlated significantly with those of myocardial and hepatic enzymes in MOF patients. Furthermore, there were marked fever, hypoproteinaemia, tissue ischaemic and hypoxic symptoms such as hyperlacticaemia, and signs reflecting tissue hypercatabolic states. These all suggested that TNF and IL-1 might play important roles in the development of MOF.

[Results of school children with enterobiasis in Tainan city, treated with mebendazole]

There were 2,471 school children suffering from enterobiasis in six primary schools of Tainan city. The infected children in five primary schools, Po-Ai, Yung-Hua, Fu-Hsiao, Pao-Jeng and Hsin-Nan, were treated with one single dosage of 100 mg mebendazole. In Shih-Men primary school, the sixth, the students were given placebos as a control group. Negative conversion rates of infected children were examined after three weeks of chemotherapy and school children in the six primary schools were surveyed for enterobiasis two months after chemotherapy to obtain infection rates. The method of examination was two consecutive-day adhesive cellophane perianal swabs. With the purpose of evaluating the efficiency of treatment, positive reduction rates were used and calculated according to the infection rates of school children gained before and after chemotherapy. Those rates in Pao-Jeng, Fu-Hsiao, Yung-Hua, Po-Ai and Hsin-Nan were 62.1%, 47.8%, 41.8%, 37.1% and 3.3%, respectively, and in Shih-Men 3.9%. Judging the data obtained from each grade or each class of schools showed that the efficacy of chemotherapy in reducing the rate of infection was variable. Hence, one single dose of mebendazole and education on personal hygiene were not sufficient to reduce the prevalence of enterobiasis in primary schools. This was because the cycle of E. vermicularis was relatively short, cutting out the routes of transmission was very difficult, and the factors involved were very complex. Overall, though the positive reduction rate presented in Hsin-Nan primary school showed nearly no success in reducing the infection, the other four schools showed valuable rates. Whether continue a treatment, of about three-months in duration, can inhibit the prevalence of enterobiasis among children in primary schools or not will need further study.

Differentiation of oval cells into duct-like cells in preneoplastic liver of rats placed on a choline-deficient diet supplemented with ethionine

Feeding male Wistar rats a choline-deficient diet containing 0.07% DL-ethionine (CDE diet) for up to 5 weeks results in the production of two distinct non-parenchymal cell populations, oval and duct-like cells. These cells can undergo replication and display different patterns of expression of glutathione S-transferases (GSTs) and pyruvate kinases (PKs). Oval cells were first detected around the periportal region after 1 week of CDE treatment and infiltrated the parenchyma after 2 weeks. Duct-like structures first appeared as isolated ducts in the parenchymal region at 2 weeks and were easily detected after 2.5 weeks. These duct-like structures differed from the bile ducts which reside in the portal region. Large concentrations of duct-like structures in cyst-like clusters were detected after 5 weeks. Enlargement of these structures from single ducts to clusters of up to 20 ducts was observed over 3-5 weeks of CDE treatment. The number of cells forming a duct increased from 5 to 30 cells. We established a double immunocytochemical staining technique to characterize the oval and duct-like cells for their expression of GSTs and PKs. pi GST and M2-PK, which are fetal hepatocytes isoenzymes, are present in virtually all the oval and duct-like cells. Most of the oval cells are devoid of the adult hepatocytes markers, alpha GST, mu GST and L-PK. There are two sub-populations of duct-like cells, one which expresses only fetal markers and the other which co-expresses the adult and fetal isoenzymes. Hence, oval cells display characteristics of fetal hepatocytes and some duct-like cells appear more mature than oval cells. Using a combination of double immunocytochemical and [3H]thymidine labelling techniques we have established that oval cells differentiate into duct-like cells.