Apoptosis of rat decidual cells: site specific initiation and related biochemical changes.

The artificially induced rat deciduoma serves as a model to study cellular changes associated with implantation in the endometrium. The stromal cells differentiate to form two types of decidual cells and are restricted to specific anatomical sites of the uterus. Programmed cell death starts in the antimesometrial area and expression of glutathione-S-transferase, an antioxidant enzyme, enhances in these cells as the deciduoma enters the regressive phase. The enzyme activity is significantly high compared with that of mesometrial decidual cells. Similarly, lipid peroxide content of antimesometrial decidual cells is high during this phase. DNA fragmentation, a feature of cells undergoing programmed cell death, is initiated in the antimesometrial area during regression of deciduoma.

Clot lysis: role of plasminogen activator inhibitors in haemostasis and therapy.

An unimpeded circulation of blood depends on the concerted activation of coagulation and fibrinolytic factors. The latter entails the controlled, localised conversion of plasma zymogen plasminogen to the active enzyme plasmin mediated by tissue-type plasminogen activator (tPA). Bulk of tPA activity is in the proximity of the endogenous plasminogen activator inhibitor (PAI) as an active complex. The advent of molecular biology techniques has enabled isolation of cDNA for the inhibitors PAI-1, PAI-2 and PAI-3 and data indicate that these belong to the serine protease inhibitor (Serpine) family with arginine as its active site but immunologically distinct from each other. Enhanced tPA or PAI-1 forms one of the risk factors related to cardiac diseases and thrombotic disorders. A line of therapy entails lowering of PAIs with concomitant increase in tPA levels leading to net enhancement in fibrinolytic activity. In as much as plasminogen activators exert their action extracellularly, they are accessible to inhibitors and therefore PAIs could have a therapeutic potential and serve as prognostic indicators in cancer. Documented findings related to the biochemical characteristics and therapeutic potential of PAIs are presented and discussed in the review.

Biogenesis of L-glyceric aciduria, oxalosis and renal injury in rats simulating type II primary hyperoxaluria.

Tracer experiments in rats mimicking type II primary hyperoxaluria, with an expanded intracellular pool of hydroxypyruvate, showed that the excess formation of oxalate did not originate from its immediate precursor glyoxylate. In these animals, the hepatic and kidney activities of oxalate synthesising enzymes such as lactate dehydrogenase and glycolate oxidase were normal, but tissue lipid peroxidation was significantly higher. In vitro experiments established that in a mild alkaline solution, hydroxypyruvate underwent auto-oxidation to form oxalate and H2O2 and also inhibited lactate dehydrogenase and glycolate oxidase from oxidising glyoxylate to oxalate. On the basis of the experimental evidence, we suggest that in type II primary hyperoxaluria, the accumulating hydroxypyruvate could reduce the intracellular pool of glyoxylate and on ageing, give rise to excess oxalate and H2O2, to cause oxalosis in the former and free radical mediated-cell injuries in the latter.

A molecular variant of plasminogen activator inhibitor of rat decidual tissue.

Artificially induced rat decidual tissue expresses plasminogen activator inhibitor (PAI). This PAI, isolated and purified employing chromatographic techniques, is a low molecular weight protein unlike the known PAIs. The final purified preparation resolves into a single band following SDS-PAGE and has an approximate molecular weight of 29 kDa. The properties studied include specificity for urokinase-type (uPA) and tissue-type (tPA) plasminogen activators, binding to conA and heparin, inhibition of thrombin, plasmin and trypsin. Decidual PAI is immunogenic in rabbit and a monospecific antiserum raised against the decidual inhibitor cross reacts with an extract of human placenta.

Differential rate of protein synthesis by antimesometrial and mesometrial decidual cells of rat.

Incorporation, in vitro, of labelled methionine into proteins of artificially induced decidual tissue shows the presence of an active protein synthetic machinery in the decidualising endometrium of rats. During the progressive phase, antimesometrial and mesometrial decidual cells, restricted to specific anatomical sites of the endometrium, synthesize proteins at varying rates and the rate of incorporation of methionine into proteins of mesometrial decidual cells is higher. Resolution of proteins on acrylamide gels following SDS electrophoresis shows qualitative changes in endometrial proteins at different stages of morphogenesis of decidual cells. Results are discussed in relation to characteristic morphological features of two decidual cell populations and differential gene expression in the decidualising endometrium.

Characterization of urokinase-type plasminogen activator of rat decidual tissue.

Urokinase-type plasminogen activator (uPA) from artificially induced decidual tissue of rat has been purified to homogeneity employing chromatographic techniques and the final preparation has a specific activity of 12,084 I.U./mg. The purified preparation resolves into a single band following SDS-PAGE and has an apparent molecular weight of 45 kDa. HPLC of the purified fraction also yields a single peak at 45 kDa. Decidual uPA is immunogenic in rabbit and a monospecific antiserum raised against it does not cross react with human melanoma tPA or rat Yoshida sarcoma tPA but elicits a precipitin reaction with human uPA and extracts of rat placenta and kidney. The enzyme has a pH optimum of 7.5, a kM of 1.0 microM, is heat stable upto ten minutes at 42 degrees C and inhibited by anti-uPA IgG.

Enhanced expression of urokinase-type plasminogen activator in the rat endometrium following induction of decidualisation.

Urokinase-type plasminogen activator(uPA) assayed in uteri of cycling and deciduoma bearing rats shows detectable levels of this enzyme in endometrium. Zymographic analysis confirms uPA of decidual tissue and, following artificial induction of decidualisation, uPA activity constantly increases in the decidualising endometrium reaching a peak on day 9 of pseudopregnancy. Endometrial uPA of nonpregnant rats does not show any significant change during estrous cycle. Results are discussed in relation to expression of this activator in endometrium of rats during morphogenesis of decidual cells.

Gestation confers temporary resistance to peroxidation in the maternal rat brain.

Lipid peroxidation, as assessed by the formation of thiobarbituric acid substances on incubation with ascorbate-Fe2+, NADPH-ADP-Fe3+ and cumene hydroperoxide in brain homogenate and mitochondria, was significantly decreased during gestation and restored to respective control levels post partum. The decrease observed with the brain homogenate on Day 10 of pregnancy was 42% with ascorbate-Fe2+ and 70% with NADPH-ADP-Fe3+. This temporary decrease in peroxidation potential seems to be due to lesser availability of substrate in the form of unsaturated fatty acids besides increase in the cholesterol:phospholipid ratio and glutathione. Progesterone, the gestational steroid elaborated during pregnancy, inhibited lipid peroxidation in brain mitochondria in a dose-dependent manner. The observed temporary decrease in peroxidation potential may be a special adaptation to protect membranes in the brain against oxidant stress during pregnancy.

Lipid peroxidation in the rat uterus during deciduoma induced cell differentiation.

The influence of deciduoma-induced differentiation on the lipid peroxidation in the rat uterus was investigated. The wet weight of uterus and its protein content increased during deciduoma progression. Content of the thiobarbituric acid reactive substances (TBARS) as well as lipid peroxidation induced by ascorbate and cumene hydroperoxide showed significant decreases during deciduoma growth. Restoration of normalcy was observed during regression. The activity of superoxide dismutase, an inhibitor of lipid peroxidation showed an opposite pattern namely increase during deciduoma development and decline during the regressive phase. We conclude that cell differentiation during deciduoma induction is accompanied by a temporary and reversible decrease in the peroxidative potential of the rat uterus.

Pregnancy-associated decrease in lipid peroxidation in rat liver.

A significant decrease in the hepatic malonaldehyde content and lipid peroxidation, induced by ascorbate, NADPH and cumene hydroperoxide, was observed during gestation in the rat. Lipid peroxidation tends to reach normal levels 3 days post partum. While a significant decrease in the lipid peroxidation of hepatic mitochondria was observed with ascorbate and NADPH, that of microsomes was affected by ascorbate and cumene hydroperoxide. The observed decrease in lipid peroxidation during pregnancy seems to be due to lesser phospholipid content, a lower degree of unsaturation in lipids, and an increase in the level of antioxidants.

Decreased lipid peroxidation in the rat kidney during gestation.

Renal malonaldehyde content and lipid peroxidation, induced by ascorbate, NADPH and cumene hydroperoxide, are significantly decreased during gestation in rats. Lipid peroxidation tends to reach normal levels in the kidney post partum. In the renal mitochondria lipid peroxidation without co-factors and that induced by cumene hydroperoxide, ascorbate and NADPH is decreased during pregnancy. However, in the microsomes, only lipid peroxidation induced by NADPH and cumene hydroperoxide is affected. The observed decrease in lipid peroxidation during gestation is reflected by low levels of total lipid and phospholipid. Endogenous inhibitors of lipid peroxidation also increase during pregnancy.

Decidualisation: origin and role of associated cells.

Proliferation of peri- and subluminal stroma following a stimulus from the blastocyst leads to the appearance of decidual cells in the mammalian endometrium. Decidualisation can also be elicited by artificial stimuli in pseudopregnant animals. A variety of histophysiological reactions accompany decidualisation and distinct morphological features characterize decidual cells localized in the antimesometrial and mesometrial area. Granulated metrial gland cells, arising in the endometrium of decidualising uterus, form a separate class of cells and become prominent in the mesometrial triangle as pregnancy advances. This review deals with factors related to induction of decidualisation; structural characteristics of decidual and metrial gland cells; the origin and postulated roles of decidualisation-associated cells. The functional role of decidual and metrial gland cells is discussed in relation to their structural complexity and recent observations on the haemopoietic origin of these cells.

Degradation of oxalate in rats implanted with immobilized oxalate oxidase.

Accumulation of oxalate leads to hyperoxaluria and calcium oxalate nephrolithiasis in man. Since oxalate is a metabolic end product in mammals, the feasibility of its enzymic degradation has been tested in vivo in rats by administering exogenous oxalate oxidase. Oxalate oxidase, isolated from banana fruit peels, in its native form was found to be non-active at the physiological pH of the recipient animal. However, its functional viability in the recipient animal was ensured by its prior binding with ethylenemaleic anhydride, thus shifting its pH activity curve towards the alkaline range. Rats implanted with dialysis membrane capsules containing such immobilized oxalate oxidase in their peritoneal cavities effectively metabolized intraperitoneally injected [14C]oxalate as well as its precursor [14C]glyoxalate. The implantation of capsules containing coentrapped multienzyme preparations of oxalate oxidase, catalase and peroxidase led to a further degradation of administered [14C]oxalate in rats.

Metrial gland: structure, origin, differentiation and role in pregnancy.

Metrial gland is a separate class of cells associated with decidualization. These granulated cells, which are early detectable in the endometrium at implantation sites, become more prominent in the mesometrial triangle of rats as pregnancy advances. Typical ultrastructural features which include the presence of pleomorphic granules characterize these cells and recent observations indicate differentiation of these cells from lymphocyte-like precursors. Presence of IgG in the cytoplasm of metrial gland cells and their origin from bone marrow suggest an immune function.

Morphogenesis and postulated functions of decidual cells.

Decidual cells are a morphologically distinct cell population arising in the endometrium during pregnancy. Decidualisation can also be elicited by artificial stimuli in suitably hormone primed animals. A variety of histophysiological reactions accompany decidualisation and culminate in the differentiation of endometrial stromal cells to decidual ones. Typical ultrastructural features characterise antimesometrial and mesometrial decidual cells. The functional role of these cells is consistent with their structural complexities and definite life span. The metrial gland forms a separate class of cells associated with decidualisation. Recent observations on the origin of both decidual and metrial gland cells from the bone marrow suggest an immunological role.

Purification and properties of gamma-glutamyl transpeptidase from rat deciduoma.

gamma-Glutamyl transpeptidase has been purified by chromatographic methods from endometrium of rat deciduoma. The membrane-bound enzyme, digested with papain, eluted as a single fraction during chromatography and the final preparation had a specific activity of 104.5 U/mg protein. The molecular weight of the native enzyme was approximately 70,000 and the protein could be resolved into a heavy and a light fraction on sodium dodecyl sulfate-acrylamide gel electrophoresis with molecular weights of 45,000 and 23,000, respectively. The enzyme had a pH optimum of 8.2 and Km's for donor (p-nitroanilide) and acceptor (glycylglycine) were 1 and 7.6 mM, respectively. The enzyme was inhibited by L-serine in the presence of borate with a Ki of 22 microM. The decidual enzyme was not heat stable and its electrophoretic mobility was decreased after neuraminidase treatment.

Effect of cycloheximide on deciduoma morphogenesis and implantation in rats.

Intraperitoneal administration of cycloheximide (1 mg/kg body weight) to rats immediately after an artificial deciduoma induction inhibits the development of decidual tissue. Besides inhibiting the differentiation of stromal to decidual cells, wet weight and levels of uterine protein and RNA are low following the antibiotic treatment. Injection of the drug (1 mg/kg body weight) into pregnant rats, either on the eve of Day 4 or in the morning of Day 5 of pregnancy, does not prevent implantation but interferes with the growth of embryos.

Effect of whole-body x-irradiation on the morphogenesis of rat deciduoma.

Exposure of rats to whole-body X-irradiation (600 R) within 30 minutes of artificial induction of deciduoma resulted in impaired growth of deciduoma involving both endometrium and myometrium. Protein synthesis in endometrium was low 2 days after X-irradiation when compared with unirradiated controls. In addition, levels of RNA and DNA were low in the endometrium of irradiated rats. Development of metrial gland was inhibited in the irradiated rats. The number and morphology of antimesometrial and mesometrial decidual cells were altered in the irradiated animals. Endometrial and myometrial soluble proteins of irradiated rats resolved into fewer bands than those of unirradiated animals.