Micromethods for analysis of lipids in endomyocardial biopsy specimens

Triglycerides and phospholipids extracted from endomyocardial biopsy specimens were quantitated with sensitive photometric methods and the fatty acid composition of phospholipids was determined after separation of the methyl esters by gas chromatography. The degree of triglyceride accumulation was expressed as the molar ratio triglyceride/phospholipid since in most cases the phospholipid concentration is relatively constant. The representativity of the analysis of endomyocardial biopsy was investigated by comparing lipid analyses of large and small myocardial specimens obtained at necropsy. The methods described may be valuable tools in studies on metabolic disturbances in different cardiomyophaties.

A randomized prospective study of misoprostol and dinoproston for induction of labor

BACKGROUND

Misoprostol, a prostaglandin E1 analog registered for the prevention of gastric ulcers in NSAID-drug users, has been reported to be more effective for labor induction than the standard prostaglandin, dinoproston after vaginal application. There have been some concerns about possible hyperstimulation of the uterine activity and about the safety for the fetus with this new drug.

METHODS

Two hundred and ten patients, 36 weeks pregnant or more, with an unfavorable cervix, single pregnancy, and intact membranes were randomized to receive misoprostol, 50 micrograms intravaginally every 6 hours, or dinoproston 0.5 mg intracervically every 12 hours for a maximum of 24 hours, for labor induction.

RESULTS

Time from induction to delivery was shorter in both primigravidae and multigravidae after the application of misoprostol than dinoproston and failed induction was more common after dinoproston than after misoprostol. There were no differences in the condition of the newborns in the two groups, according to Apgar score, umbilical artery pH or referral to the neonatal unit, even if there were more operative deliveries for suspected fetal asphyxia after misoprostol than after dinoproston. We did not find any significant difference in the frequency of uterine hyperstimulation between the two groups.

CONCLUSIONS

In the dosage used, misoprostol seems to be an effective agent for induction of labor in patients with an unfavorable cervix. Low cost and ease of administration make this drug a promising alternative for this purpose. Surprisingly, there is little interest from the manufacturer to promote the use of this drug for labor induction.

[Large fetus--a retrospective study]

BACKGROUND

Large foetus is associated with increased risk of complications during labour and delivery.

MATERIAL AND METHODS

Data on deliveries and outcome of 504 macrosomic newborns (> or = 4,500 g) born 1995-97 at Rogaland Central Hospital, Norway.

RESULTS

74% of the mothers were multiparae. Mean weight increase during pregnancy was 17.6 kg. In 76% of the pregnancies delivery occurred after term. There were large margins of error both in terms of measurement of fundal height and after estimation with ultrasound. 12% of the newborns had shoulder dystocia. Six children were diagnosed with a brachial plexus injury; three injuries were still present three months after birth. Induction of labour did not increase the Apgar score or diminish the frequency of shoulder dystocia, but it did increase the frequency of operative deliveries and transfer to the neonatal unit.

INTERPRETATION

The study confirms that large foetus is associated with risk of complications.

Phosphorylation and activation of hormone-sensitive adipocyte phosphodiesterase type 3B

Phosphodiesterases (PDEs) include a large group of structurally related enzymes that belong to at least seven related gene families (PDEs 1-7) that differ in their primary structure, affinity for cAMP and cGMP, response to specific effectors, sensitivity to specific inhibitors, and regulatory mechanism. One characteristic of PDE3s involves their phosphorylation and activation in response to insulin as well as to agents that increase cAMP in adipocytes, hepatocytes, and platelets and in response to insulin-like growth factor 1 in pancreatic beta cells. In adipocytes, activation of the membrane-associated PDE3B is the major mechanism whereby insulin antagonizes catecholamine-induced lipolysis. PDE3B activation results in increased degradation of cAMP and, thereby, a lowering of the activity of cAMP-dependent protein kinase (PKA). The reduced activity of PKA leads to a net dephosphorylation and decreased activity of hormone-sensitive lipase and reduced hydrolysis of triglycerides. Activation of the rat adipocyte PDE3B by insulin is associated with phosphorylation of serine-302. The mechanism whereby insulin stimulation leads to phosphorylation/activation of PDE3B is only partly understood. In rat adipocytes, lipolytic hormones and other agents that increase cAMP, including isoproterenol, also induce rapid phosphorylation, presumably catalyzed by PKA, of serine-302 of PDE3B. The phosphorylation is associated with activation of the enzyme, most likely representing "feedback" regulation of cAMP, presumably allowing close coupling of the regulation of steady-state concentrations of both cAMP and PKA and, thereby, control of lipolysis. In the review we describe methods and strategies used in the authors' laboratories to study phosphorylation and activation of PDE3B in adipocytes and in vitro.

Insulin-induced phosphorylation and activation of phosphodiesterase 3B in rat adipocytes: possible role for protein kinase B but not mitogen-activated protein kinase or p70 S6 kinase

Insulin stimulation of adipocytes results in serine phosphorylation/activation of phosphodiesterase 3B (PDE 3B) and activation of a kinase that phosphorylates PDE 3B in vitro, key events in the antilipolytic action of this hormone. We have investigated the role for p70 S6 kinase, mitogen-activated protein kinases (MAP kinases), and protein kinase B (PKB) in the insulin signaling pathway leading to phosphorylation/activation of PDE 3B in adipocytes. Insulin stimulation of adipocytes resulted in increased activity of p70 S6 kinase, which was completely blocked by pretreatment with rapamycin. However, rapamycin had no effect on the insulin-induced phosphorylation/activation of PDE 3B or the activation of the kinase that phosphorylates PDE 3B. Stimulation of adipocytes with insulin or phorbol myristate acetate induced activation of MAP kinases. Pretreatment of adipocytes with the MAP kinase kinase inhibitor PD 98059 was without effect on the insulin-induced activation of PDE 3B. Furthermore, phorbol myristate acetate stimulation did not result in phosphorylation/activation of PDE 3B or activation of the kinase that phosphorylates PDE 3B. Using Mono Q and Superdex chromatography, the kinase that phosphorylates PDE 3B was found to co-elute with PKB, but not with p70 S6 kinase or MAP kinases. Furthermore, both PKB and the kinase that phosphorylates PDE 3B were found to translocate to membranes in response to peroxovanadate stimulation of adipocytes in a wortmannin-sensitive way. Whereas these results suggest that p70 S6 kinase and MAP kinases are not involved in the insulin-induced phosphorylation/activation of PDE 3B in rat adipocytes, they are consistent with PKB being the kinase that phosphorylates PDE 3B.

Regulation of protein kinase B in rat adipocytes by insulin, vanadate, and peroxovanadate. Membrane translocation in response to peroxovanadate

Protein kinase B (PKB) (also referred to as RAC/Akt kinase) has been shown to be controlled by various growth factors, including insulin, using cell lines and transfected cells. However, information is so far scarce regarding its regulation in primary insulin-responsive cells. We have therefore used isolated rat adipocytes to examine the mechanisms, including membrane translocation, whereby insulin and the insulin-mimicking agents vanadate and peroxovanadate control PKB. Stimulation of adipocytes with insulin, vanadate, or peroxovanadate caused decreased PKB mobility on sodium dodecyl sulfate-polyacrylamide gels, indicative of increased phosphorylation, which correlated with an increase in kinase activity detected with the peptide KKRNRTLTK. This peptide was found to detect activated PKB selectively in crude cytosol and partially purified cytosol fractions from insulin-stimulated adipocytes. The decrease in electrophoretic mobility and activation of PKB induced by insulin was reversed both in vitro by treatment of the enzyme with alkaline phosphatase and in the intact adipocyte upon removal of insulin or addition of the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor wortmannin. Significant translocation of PKB to membranes could not be demonstrated after insulin stimulation, but peroxovanadate, which appeared to activate PI 3-kinase to a higher extent than insulin, induced substantial translocation. The translocation was prevented by wortmannin, suggesting that PI 3-kinase and/or the 3-phosphorylated phosphoinositides generated by PI 3-kinase are indeed involved in the membrane targeting of PKB.

Protein kinase A-dependent activation of PDE4 (cAMP-specific cyclic nucleotide phosphodiesterase) in cultured bovine vascular smooth muscle cells

Incubation of cultured bovine vascular smooth muscle cells (VSMC) with forskolin increased cAMP as measured by an increase in cAMP-dependent protein kinase (PKA) activation (PKA ratio). Forskolin also produced a concentration- and time-dependent increase in activity (3-5-fold within 15 min) of a PDE4 (cAMP-specific cyclic nucleotide phosphodiesterase). The increase in PDE4 activity was not affected by cycloheximide and thus not likely due to increased synthesis of the enzyme. Activation, which was preserved during partial purification of the enzyme by chromatography on Sephacryl S-200 and MonoQ, was most likely due to a covalent modification. Incubation of cell homogenates with the catalytic subunit of PKA (PKA(c)) induced a approximately 5-fold activation of PDE4 with a time course similar to that in intact cells after forskolin addition. The forskolin-mediated activation was reversed during incubation of homogenates at room temperature for two hours. Addition of PKA(c) resulted in rapid reactivation of PDE4. These data are consistent with the hypothesis that rapid, reversible activation of PDE4 in cultured VSMC is mediated by PKA.

Identification of the site in the cGMP-inhibited phosphodiesterase phosphorylated in adipocytes in response to insulin and isoproterenol

Stimulation of rat adipocytes with insulin and isoproterenol results in serine phosphorylation and activation of the adipocyte cGMP-inhibited phosphodiesterase (cGI PDE), events believed to be important in the antilipolytic action of insulin (Degerman, E., Smith, C.J., Tornqvist, H., Vasta, V., Manganiello, V.C., and Belfrage, P. (1990) Proc. Natl. Acad. Sci. U.S.A. 87,533-537). Here we demonstrate, by two-dimensional phosphopeptide mapping, that the major phosphopeptide generated by trypsin, or trypsin followed by Asp-N protease digestion of [32P]cGI PDE phosphorylated in adipocytes in response to isoproterenol and/or insulin, in each case co-migrates with the phosphopeptide released by the same treatment of M297FRRPS(P)LPCISREQ310. This peptide was synthesized based on the deduced sequence of the cloned rat adipocyte cGI PDE and phosphorylated by cAMP-dependent protein kinase (protein kinase A). Radiosequencing of authentic and synthetic tryptic 32P-peptides showed that a single site in cGI PDE (Ser302) was phosphorylated in adipocytes incubated with isoproterenol and/or insulin. The more than additive phosphorylation and activation of cGI PDE in response to the two hormones found in this report and previously (Smith, C.J., Vasta, V., Degerman, E., Belfrage, P., and Manganiello, V.C. (1991) J. Biol. Chem. 266, 13385-13390) is proposed to reflect cross-talk between their respective signal transduction pathways at the level of the cGI PDE serine protein kinase or upstream regulatory component(s).

Type III cGMP-inhibited cyclic nucleotide phosphodiesterases (PDE3 gene family)

Seven different but related cyclic nucleotide phosphodiesterase (PDE) gene families have been identified. Type III cGMP-inhibited (cGI) PDEs, the PDE3 gene family, are found in many tissues. cGI PDEs exhibit a high affinity for both cAMP and cGMP, and are selectively and relatively specifically inhibited by certain agents which augment myocardial contractility, promote smooth muscle relaxation and inhibit platelet aggregation. Adipocyte, platelet, and hepatocyte cGI PDE activities are regulated by cAMP-dependent phosphorylation. Insulin-induced phosphorylation/activation of adipocyte and hepatocyte cGI PDEs is thought to be important in acute regulation of triglyceride and glycogen metabolism by insulin. Two distinct cGI PDE subfamilies, products of distinct but related genes, have been identified. They exhibit the domain structure common to PDEs with a carboxyterminal region, conserved catalytic domain and divergent regulatory domain. In their catalytic domains cGI PDEs contain a 44 amino acid insertion not found in other PDE families. The expression of cGIP1 and cGIP2 mRNAs differs in different rat tissues, suggesting distinct functions for the two cGI PDE subfamilies, i.e., cGIP1 in adipose tissue, liver, testis and cGIP2 in myocardium, platelets and smooth muscle.

Evidence for the key role of the adipocyte cGMP-inhibited cAMP phosphodiesterase in the antilipolytic action of insulin

Enhancement of cAMP degradation by increased cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) activity is thought to be an important component of the mechanism whereby insulin counteracts catecholamine-induced lipolysis in adipocytes. In this study the selective cGI-PDE inhibitor OPC3911 was used to evaluate this role of cGI-PDE activation in intact rat adipocytes with special reference to changes in cAMP levels measured as cAMP-dependent protein kinase (cAMP-PK) activity ratios. OPC3911 completely blocked (IC50 = 0.3 microM) the maximal inhibitory effect of insulin on noradrenaline-induced lipolysis and the net dephosphorylation of hormone-sensitive lipase and other intracellular target proteins for insulin action, whereas insulin-induced lipogenesis was not changed. The effect of OPC3911 on cAMP-PK activity ratios at different levels of lipolysis achieved by noradrenaline stimulation revealed that the reduction of cAMP-PK caused by 1 nM insulin was completely blocked by 3 microM OPC3911. The effect of OPC3911 was not due to an excessive increase in cellular cAMP resulting in 'supramaximal' lipolysis unresponsive to insulin. These data demonstrate that reduction in cAMP levels by the activation of cGI-PDE may be sufficient to account for the antilipolytic action of insulin.

Essential role of phosphatidylinositol 3-kinase in insulin-induced activation and phosphorylation of the cGMP-inhibited cAMP phosphodiesterase in rat adipocytes. Studies using the selective inhibitor wortmannin

Incubation of rat adipocytes with wortmannin, a potent and selective phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor, completely blocked the antilipolytic action of insulin (IC50 = 100 nM), the insulin-induced activation and phosphorylation of cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) as well as the activation of the insulin-stimulated cGI-PDE kinase (IC50 = 10-30 nM). No direct effects of the inhibitor on the insulin-stimulated cGI-PDE kinase, the cGI-PDE and the hormone-sensitive lipase were observed. These data suggest that activation of PI 3-kinase upstream of the insulin-stimulated cGI-PDE kinase in the antilipolytic insulin signalchain has an essential role for insulin-induced cGI-PDE activation/phosphorylation and anti-lipolysis.

Lipoprotein lipase and hormone-sensitive lipase activity and mRNA in rat adipose tissue during pregnancy

To investigate the factors controlling maternal depot fat accumulation during early pregnancy and net decrease during late pregnancy, the activity and mRNA expression of adipose tissue lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) were related to several other lipid metabolic parameters. Virgin control rats, pregnant rats (at days 12, 15, 19, and 21), and lactating rats (at days 5 and 10 postpartum) were studied. In adipose lumbar tissue of late pregnant rats, LPL activity decreased to about one-third that of the virgin control animals, with < 10% of initial LPL mRNA expressed as determined by Northern blots. HSL activity increased maximally 1.5-fold with a fourfold increase of HSL expression at days 12-15 of pregnancy and decreased to control levels after parturition. The HSL-to-LPL mRNA and activity ratios were enhanced from days 15 and 19 of pregnancy, respectively, and remained so even during lactation, mainly because of the marked lowering of the LPL values. This enhancement coincided with increments in plasma free fatty acids and glycerol levels indicating an increased depot fat breakdown. These results give no indication of an involvement of LPL and HSL gene expression changes in the accumulation of maternal depot during early pregnancy. In contrast, such changes could be responsible for the net breakdown of this fat depot during late gestation. Thus, during this physiological state, long-term (e.g., transcriptional) regulation of LPL and HSL gene expression could be an important mechanism for the control of adipose tissue mass breakdown during late gestation.

Identification of the phosphorylation site in vitro for cAMP-dependent protein kinase on the rat adipocyte cGMP-inhibited cAMP phosphodiesterase

Rat adipocyte cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) appears to be dually regulated in intact cells by serine phosphorylations induced by isoprenaline and insulin, respectively (Degerman, E., Smith, C. J., Tornqvist, H., Vasta, V., Belfrage, P., and Manganiello, V. C. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 533-537; Smith, C. J., Vasta, V., Degerman, E., Belfrage, P., and Manganiello, V. C. (1991) J. Biol. Chem. 266, 13385-13390). Since cAMP-dependent protein kinase (cAMP-PK) catalyzes the beta-adrenergic effects, the site in the isolated cGI-PDE phosphorylated by this kinase was explored. A peptide, LRRSSGASGLLTSEHHSR (P18), corresponding to the amino acid sequence Leu423-Arg440 in the putative regulatory domain of the rat adipocyte cGI-PDE was synthesized. It contains a consensus substrate sequence -RRXS- for cAMP-PK within two tryptic cleavage sites and was readily phosphorylated by cAMP-PK. Two phosphopeptides, identified as RS-[32P]SGASGLLTSEHHSR and S-[32P]SGASGLLTSEHHSR, were obtained after stoichiometric phosphorylation and trypsinization of the peptide. These two peptides and the two main tryptic phosphopeptides obtained from immunoisolated [32P]cGI-PDE phosphorylated with cAMP-PK in a solubilized crude adipocyte membrane fraction were immuno-precipitated by an affinity-purified polyclonal antibody raised against P18 and exhibited the same chromatographic and electrophoretic profiles in three different separation systems. Similar radiosequencing profiles indicated that the second most N-terminal serine, corresponding to Ser-427 in the intact cGI-PDE, was phosphorylated by cAMP-PK in both P18 and authentic cGI-PDE. It is concluded that serine 427 is the target for cAMP-PK phosphorylation of the rat adipocyte cGI-PDE in vitro.

Single-step affinity purification, partial structure and properties of human platelet cGMP inhibited cAMP phosphodiesterase

The human platelet cilostamide- and cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) was rapidly purified approximately 19,000-fold to apparent homogeneity using single step affinity chromatography on the isothiocyanate derivative of cilostamide coupled to aminoethyl agarose. Within 24 h, 30 micrograms of enzyme protein was obtained from 20 ml of packed platelets. Vmax for cAMP and cGMP was 6.1 and 0.9 mumol/min per mg protein, respectively. Several polypeptides (110/105, 79, 62, 55/53 kDa) were identified after SDS-PAGE, all of which were immunologically related to cGI-PDE and represented approx. 5, 20, 50 and 20% of the total protein, respectively. Limited proteolysis of the cGI-PDE with chymotrypsin produced a major fragment of approximately 47 kDa (and at least two smaller peptides) with catalytic activity and sensitivity to cGMP and OPC 3911 similar to controls. Phosphorylation of the cGI-PDE by cAMP-dependent protein kinase (A-kinase) resulted in maximal incorporation of 0.6-1.8 mol of 32P/mol 110/105 and 79 kDa polypeptides; much lower and variable amounts of phosphate were incorporated into the 62 and 55/53 kDa polypeptides. After digestion of cGI-PDE with several proteinases a number of peptides were isolated and sequenced. Most of the peptide sequences obtained could be aligned within the carboxy terminal domain of the deduced sequence of the human cardiac cGI-PDE. These and other results suggest that the subunit size of the intact platelet cGI-PDE is 110 kDa and that proteolytic fragments of 79, 62 and 55/53 kDa are produced during purification. The smaller fragments (62 and 55/53 kDa) contain the catalytic domain; the larger fragments (110 and 79 kDa) also contain the regulatory domain with phosphorylation sites for A-kinase.

Hormone-sensitive lipase: structure, function, evolution and overproduction in insect cells using the baculovirus expression system

Hormone-sensitive lipase (HSL) catalyses the rate-limiting step in the hydrolysis of stored triacylglycerols and is thereby a key enzyme in lipid metabolism and overall energy homeostasis. The gene organization of human HSL indicates that each putative functional region is encoded by a different exon, raising the possibility that HSL is a mosaic protein. The catalytic serine (Ser423), as shown by site-directed mutagenesis, is encoded by exon 6. The phosphorylation site for cAMP-mediated activity control and a second site, which is presumably phosphorylated by 5' AMP-activated kinase, are encoded by exon 8, and a putative lipid-binding region is encoded by the ninth and last exon. Besides the catalytic site serine motif (GXSXG), found in virtually all lipases, a sequence similarity between the region surrounding the catalytic site of HSL and that of five prokaryotic enzymes has been found, but the functional basis of this is not yet understood. To resolve the 3-D structure of HSL, an expression system utilizing recombinant baculovirus and insect cells has been established. The expressed protein, 80 mg/l culture, has been purified to homogeneity and a partial characterization indicates that it has the same properties as HSL purified from rat adipose tissue.

Comparison of outcome of labetalol or hydralazine therapy during hypertension in pregnancy in very low birth weight infants

Ninety-seven women with moderate to severe preeclampsia (PE) were allocated at random to labetalol or hydralazine treatment. Of these, 22 women with severe PE gave birth to neonates with VLBW (very low birth weight < or = 1500 g). Seven were allocated to labetalol treatment (Group A), eight to hydralazine treatment (Group B) and seven women received both drugs due to poor blood pressure control with a single drug therapy (Group C). No difference in cesarean section rate or in the indication for operative delivery could be seen. Gestational age was 29.9 weeks (25.4-32.5) in Group A, 28.6 weeks (26.6-33.4) in Group B and 27.3 weeks (26.7-31.1) in Group C (median and range). Birth weight did not differ between groups and 13 of the 22 infants weighed below 1000 g. There was a tendency to lower Apgar scores at five minutes in the hydralazine group. Time spent in the neonatal intensive care unit did not differ between groups. Five of the 11 neonates with gestational age (GA) < or = 28 weeks and three of the seven neonates in GA 29-30 weeks died. Neither the number of infants requiring intermittent positive pressure ventilation or duration of O2- treatment, nor number of infants with respiratory distress syndrome differed between groups. We did not find any difference in the outcome of the VLBW infants when the hypertensive mother had been treated with either hydralazine or labetalol.

Molecular cloning of the rat adipocyte hormone-sensitive cyclic GMP-inhibited cyclic nucleotide phosphodiesterase

Two distinct but related cGMP-inhibited cyclic nucleotide phosphodiesterase (cGI PDE) cDNAs were cloned from rat adipose tissue cDNA libraries. The open reading frame (3324 base pairs) of RcGIP1 encodes 1108 amino acids, including a hydrophobic membrane-associated domain in the NH2-terminal portion and, in the COOH-terminal portion, a putative catalytic domain conserved among all mammalian PDEs which is preceded by a putative regulatory domain that contains three consensus cAMP-dependent protein kinase phosphorylation sites and followed by a hydrophilic COOH-terminal domain. The carboxyl-terminal portion including the conserved domain was expressed as a glutathione S-transferase fusion protein and exhibited cAMP PDE activity which was inhibited by cilostamide, a specific cGI PDE inhibitor. RcGIP1 cDNA hybridizes strongly with RNA from isolated adipocytes, and its mRNA increases dramatically during differentiation of 3T3-L1 adipocytes. The deduced sequence of the second partial cDNA clone (RcGIP2 clone 53B) is highly homologous to the corresponding region of human cardiac cGI PDE cDNA. RcGIP2 cDNA hybridized strongly with rat cardiac tissue RNA and weakly if at all with RNA from rat adipocytes or 3T3-L1 fibroblasts or adipocytes. We suggest that RcGIP1 represents the hormone-sensitive, membrane-associated rat adipocyte cGI PDE and RcGIP2, a cGI PDE from vascular elements in rat adipose tissue.

Stimulation by insulin of a serine kinase in human platelets that phosphorylates and activates the cGMP-inhibited cAMP phosphodiesterase

We previously reported that insulin stimulation of human platelets induces serine phosphorylation and activation of the cGMP-inhibited cAMP phosphodiesterase (cGI-PDE). Here, we describe methods to detect and partially purify an insulin-stimulated cGI-PDE kinase (cGI-PDE ISK) from lysates of platelets incubated with insulin. Incubation of human platelets with 10(-8) M insulin increased cGI-PDE ISK activity two-fold. The DEAE-Sephacel-purified cGI-PDE ISK phosphorylated the cGI-PDE on serine in a time- and concentration-dependent manner resulting in an increased incorporation of about 0.2 mol of [32P]/mol of cGI-PDE and 15-20% increase in cGI-PDE activity. The phosphorylation of cGI-PDE was not affected by 10 microM PKI, 1 microgram/ml of heparin, 3 mM CaCl2 or 1 mM MnCl2. cGI-PDE ISK did not adsorb to antiphosphotyrosine antibodies. To maintain its activation it was necessary to add protein phosphatase inhibitors to the lysate-buffers. All of these findings are consistent with the conclusion that a serine/threonine phosphorylation of the cGI-PDE ISK is involved in its activation by insulin.

Gene organization and primary structure of human hormone-sensitive lipase: possible significance of a sequence homology with a lipase of Moraxella TA144, an antarctic bacterium

The human hormone-sensitive lipase (HSL) gene encodes a 786-aa polypeptide (85.5 kDa). It is composed of nine exons spanning approximately 11 kb, with exons 2-5 clustered in a 1.1-kb region. The putative catalytic site (Ser423) and a possible lipid-binding region in the C-terminal part are encoded by exons 6 and 9, respectively. Exon 8 encodes the phosphorylation site (Ser551) that controls cAMP-mediated activity and a second site (Ser553) that is phosphorylated by 5'-AMP-activated protein kinase. Human HSL showed 83% identity with the rat enzyme and contained a 12-aa deletion immediately upstream of the phosphorylation sites with an unknown effect on the activity control. Besides the catalytic site motif (Gly-Xaa-Ser-Xaa-Gly) found in most lipases, HSL shows no homology with other known lipases or proteins, except for a recently reported unexpected homology between the region surrounding its catalytic site and that of the lipase 2 of Moraxella TA144, an antarctic psychrotrophic bacterium. The gene of lipase 2, which catalyses lipolysis below 4 degrees C, was absent in the genomic DNA of five other Moraxella strains living at 37 degrees C. The lipase 2-like sequence in HSL may reflect an evolutionarily conserved cold adaptability that might be of critical survival value when low-temperature-mobilized endogenous lipids are the primary energy source (e.g., in poikilotherms or hibernators). The finding that HSL at 10 degrees C retained 3- to 5-fold more of its 37 degrees C catalytic activity than lipoprotein lipase or carboxyl ester lipase is consistent with this hypothesis.

Conservative treatment of mild and moderate hypertension in pregnancy

In a prospective study regarding conservative treatment of mild to moderate hypertension in pregnancy 5244 women were evaluated at delivery. Two hundred and fifty-eight (4.9%) were registered as hypertensive during pregnancy with a blood pressure (BP) greater than or equal to 140/90 mmHg. One hundred and ninety-six of these continued their pregnancy without medication and 96/196 were defined as preeclamptic (PE), 45/196 as chronic hypertensive (CH), and 55/196 as having gestational hypertension (GH). In 62/258 women antihypertensive treatment was initiated in the mean 6.5 (+/- 8.7) days after onset of hypertension, due to a BP greater than or equal to 150/100 mmHg. There was a later onset of hypertension in the untreated group, and BP at delivery differed in the untreated groups (p less than 0.001) with the lowest BP in women with mild GH. There was no difference in cesarean section rate in the mild hypertensive group as compared to the normal population. Birth weight and length of pregnancy were significantly lower in the untreated mild hypertensive group as compared to normal pregnant women (p less than 0.05). But in the subgroup with mild GH pregnancy length and birth weight did not differ from normal pregnancy. The conclusion from our study is that women with mild hypertension in pregnancy might refrain from antihypertensive therapy if they are closely observed during pregnancy and delivery, especially if there has been no hypertension before pregnancy and no proteinuria develops.

Insulin induced phosphorylation and activation of the cGMP-inhibited cAMP phosphodiesterase in human platelets

Insulin induced phosphorylation and activation of the cGMP inhibited cAMP phosphodiesterase (cGI-PDE) in human platelets were demonstrated after isolation of the enzyme with specific polyclonal cGI-PDE antibodies. The demonstration of this insulin effect required suppression of basal cGI-PDE phosphorylation, through the use of the protein kinase inhibitor H-7 (1-(5-isoquinolinylsulfonyl)-2-methylpiperazine). The human platelet insulin receptor beta-subunit, previously identified as a 97 kDa polypeptide, was detected with the use of wheat germ agglutinin chromatography and anti-phosphotyrosine antibodies. These results suggest that insulin, through phosphorylation/activation of cGI-PDE, could decrease cAMP/cAMP dependent protein kinase (cAMP-PK) activity and thereby make the platelets more sensitive towards aggregating agents.

Purification and characterization of guanosine 3',5'-monophosphate-inhibited low K(m) adenosine 3',5'-monophosphate phosphodiesterase from human placental cytosolic fractions

We previously characterized human placental cytosolic cAMP phosphodiesterase (PDE) and found that two low K(m) cAMP PDE isoforms that were very sensitive to inhibition by cGMP and cilostamide were activated by insulin. As a first step toward understanding the mechanisms by which insulin activates this enzyme, we purified the cGMP-inhibited low K(m) cAMP PDE (cGI-PDE) from human placentas. The enzyme was purified 11,700-fold from a pool of 100,000 x g supernatant fractions of 10-15 placentas by ammonium sulfate precipitation, diethylaminoethyl-cellulose chromatography, and affinity chromatography, using an isothiocyanate derivative of cilostamide (CIT-agarose). The specific activity of the affinity-purified enzyme was 432 +/- 17 nmol/min.mg (mean +/- SD; n = 4). Gel permeation chromatography of the CIT-agarose eluates revealed one protein peak that coincided with PDE activity at an elution position of 135,000 daltons. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of this protein peak and CIT-agarose eluates revealed the same patterns, indicating that the purified PDE preparations contained multiple proteins with apparent mol wt of 138K, 83K, 72K, 67K, 63K, and 44K. The 138K form appears to be an intact enzyme; an analogous approximately 135K form has recently been identified in rat adipocyte particulate fractions by specific immunoprecipitation or Western immunoblots. In addition, other smaller forms eluted at 135,000 daltons on gel permeation chromatography, suggesting that, although proteolyzed, they must have been associated by either noncovalent interactions or disulfide bonds. All of the protein bands observed on the sodium dodecyl sulfate-polyacrylamide electrophoresis gel reacted with rabbit antibodies raised against human platelet cGI-PDE. Ten peptides from endoproteinase Lys-C-digests of the affinity-purified placental cGI-PDE were isolated and sequenced; sequences of eight peptides were identical to the deduced amino acid sequences in the C-terminal half of a human heart cGI-PDE cDNA, while those of two peptides were not found in the heart enzyme. The sequences of the eight peptides also matched peptide sequences derived from a purified human platelet cGI-PDE. These results provide evidence that the catalytic C-terminal half domain of the placental insulin-sensitive cGI-PDE shares homology with those of human heart and platelet cGI-PDEs. K(m) and maximum velocity values for cAMP and cGMP were 0.57 microM and 862 nmol/min.mg, and 15 microM and 467 nmol/min.mg, respectively. ED50 values for cGMP, cilostamide, and Ro 20-1724 were 0.12, 0.22, and 120 microM, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

cAMP-dependent protein kinase activation mediated by β3-adrenergic receptors parallels lipolysis in rat adipocytes

Catecholamine-induced lipolysis is chiefly mediated through the recently characterized beta 3-adrenergic receptor (AR) in rat adipocytes. Discrepancies between the ability of beta 3-AR agonists to stimulate adenylyl cyclase and the resulting lipolysis were recently reported. cAMP-dependent protein kinase (A-kinase) activation induced by these agonists was compared to lipolysis. Agonist potencies were similar for A-kinase activity ratios and lipolysis. The same A-kinase activity ratio to lipolysis relationship was found for the beta 3-AR agonists tested.

Allo-immunization during pregnancy. Clinical results from 1983 to 1989 in a Scandinavian university hospital

From 1983 to 1989, 147,068 pregnancies were analyzed for allo-immunization against erythrocyte antigens. Approximately half of the cases were due to immunization against factor D and the others were due to allo-immunization against other antigens (K, c, E, etc.). In 61 cases exchange transfusion of the newborn was needed and in 115 cases diagnostic amniocentesis was done during pregnancy. Intrauterine transfusions were performed in 10 cases. Fetal and neonatal mortality was 4% in these moderate to severe cases, all due to immunization against D. Immunization against D was due to failure to give immunoglobulin anti-D in about 2/3 of the cases. Systematic prophylactic treatment with anti-D during pregnancy would probably not be cost-effective in this population.

Molecular cloning and expression of human myocardial cGMP-inhibited cAMP phosphodiesterase

We have cloned a cDNA for a myocardial cGMP-inhibited cAMP phosphodiesterase (cGI PDE) from a human heart cDNA library in lambda Zap II. The open reading frame [3.5 kilobases (kb)] of cDNA clone n.13.2 (7.7 kb) encodes a protein of 125 kDa. In Northern blots of total human ventricle RNA, a single mRNA species (8.3 kb) hybridized with a 4-kb EcoRI restriction fragment of clone n.13.2 cDNA (containing the entire open reading frame). The carboxyl-terminal region of the deduced amino acid sequence of the cGI PDE contains the putative catalytic domain conserved among mammalian PDE families. A partial cDNA clone, n.2, encoding a truncated, 54-kDa cGI PDE containing the conserved domain was expressed as a catalytically active fusion protein in Escherichia coli. cAMP hydrolytic activity was inhibited by cGMP and OPC 3911 but not by rolipram. Thus, this report provides direct proof that the conserved domain contains the catalytic core of cGI PDEs.

Insulin and isoproterenol induce phosphorylation of the particulate cyclic GMP-inhibited, low Km cyclic AMP phosphodiesterase (cGI PDE) in 3T3-L1 adipocytes

The cGI PDE in particulate fractions of differentiated adipocytes (but not control 3T3-L1 fibroblasts) was cross-reactive with a polyclonal antibody raised against the bovine adipose cGI PDE. The 3T3-L1 adipocyte cGI PDE is a 135 kDa protein which is phosphorylated in 32P-labeled cells in response to beta-agonist or insulin. These results indicate that the 3T3-L1 cGI PDE is similar in structure and hormonal regulation to the analogous enzyme in the rat adipocyte.

Purification and properties of the cGMP-inhibited cAMP phosphodiesterase from bovine aortic smooth muscle

Pure cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) in micrograms quantities was isolated from bovine aortic smooth muscle after more than 5000-fold purification using DEAE ion-exchange and affinity chromatography with a derivative of the specific cGI-PDE inhibitor cilostamide conjugated as a ligand to aminoethyl agarose (CIT-agarose). The cGI-PDE, which constituted about half of the high affinity cAMP-PDE activity of a tissue homogenate, was identified with a 105-kDa protein on SDS-PAGE through use of antibodies towards the human platelet, bovine cardiac and bovine adipose tissue cGI-PDE in Western blot and immunoprecipitation/immunoinactivation analysis. As observed during purification of the enzyme from other tissues the enzyme protein was exquisitely sensitive to proteolytic nicking during purification, resulting in several 30-77-kDa polypeptide fragments. Rapid immunoprecipitation from fresh tissue extracts was the only was found to partially prevent the proteolysis. The native enzyme had apparent molecular sizes of approx. 100,000 or, mainly approx. 220,000 by gel chromatography, presumably indicating the presence of monomeric and dimeric forms. The enzyme hydrolyzed cAMP and cGMP with normal Michaelis-Menten kinetics with Km of 0.16 and 0.09 microM, respectively, with Vmax for hydrolysis of cAMP of 0.3 compared to 3.1 mumol/min per mg protein for cAMP. The enzyme was potently and selectively inhibited by cGMP (IC50 approximately 0.25 microM) and the cardiotonic/vasodilatory drugs OPC-3911 (a cilostamide derivative), milrinone and CI-930 (IC50 approximately 0.05, 0.40 and 0.25 microM, respectively). The cGI-PDE was phosphorylated by cAMP-dependent protein kinase as has been reported for the analogous enzymes in heart, adipose tissue and platelets. The identification of a cGI-PDE in the aortic smooth muscle and its inhibitor specificity is consistent with the hypothesis that inhibition of this enzyme is important in the mechanism through which these drugs produce vasorelaxation.

Hormone-sensitive cyclic GMP-inhibited cyclic AMP phosphodiesterase in rat adipocytes. Regulation of insulin- and cAMP-dependent activation by phosphorylation

In 32PO4-labeled adipocytes, isoproterenol (ISO) or physiologically relevant concentrations of insulin rapidly increased phosphorylation of a particulate 135-kDa protein which has been identified as a cGMP-inhibited "low Km" cAMP phosphodiesterase (CGI-PDE) by several criteria, including selective immunoprecipitation with anti-CGI-PDE IgG (Degerman, E., Smith, C.J., Tornqvist, H., Vasta, V., Belfrage, P., and Manganiello, V.C. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 533-537). The time courses and concentration dependences for phosphorylation of CGI-PDE by ISO and insulin correlated with CGI-PDE activation in the presence of these agents; effects of ISO were somewhat more rapid than those of insulin. Adenosine deaminase, which metabolizes the adenylate cyclase inhibitor adenosine, also rapidly induced phosphorylation and activation of CGI-PDE. Phenylisopropyladenosine (an adenosine deaminase-resistant adenosine analog) prevented or reversed both adenosine deaminase-stimulated phosphorylation and activation of CGI-PDE (IC50 approximately 0.2 nM). Incubation of adipocytes with 0.1 nM insulin in the presence of ISO rapidly produced 30-200% greater activation and phosphorylation of CGI-PDE than the expected added effects of insulin and ISO individually; both effects preceded the insulin-induced decreases in protein kinase A activity and inhibition of lipolysis. These and other results indicate that CGI-PDE can be phosphorylated at distinct sites and activated by cAMP-dependent and insulin-dependent serine kinase(s), that the activation state of CGI-PDE reflects its relative phosphorylation state, and that synergistic phosphorylation/activation of CGI-PDE may be important in the antilipolytic action of insulin.

Expression of biologically active hormone-sensitive lipase in mammalian (COS) cells

cDNAs encoding rat adipose tissue hormone-sensitive lipase were expressed in COS cells, under the control of the SV40 promoter to half the level in rat adipocytes, the richest native source of the enzyme. A cDNA lacking most of the long 5'-untranslated region of the full-length rat hormone-sensitive lipase cDNA was, with regard to the lipase activity, on the average 70% more efficiently expressed that the full-length cDNA. The recombinant protein was almost identical to hormone-sensitive lipase of rat adipose tissue with respect to specific activity, susceptibility to inhibitors, molecular size, phosphorylation and activation by cyclic AMP-dependent protein kinase. The described eukaryotic expression system will allow analysis of effects of amino acid substitutions introduced into the lipase molecule by site-directed mutagenesis.

Hemodynamic measurements with Swan-Ganz catheter in women with severe proteinuric gestational hypertension (pre-eclampsia)

Ten women with severe pre-eclampsia, i.e. a blood pressure greater than or equal to 150/110 mmHg or 140/90 mmHg and proteinuria greater than 3 g/24 h were, after initial antihypertensive treatment, centrally monitored with a pulmonary artery catheter (Swan-Ganz). All had been normotensive in early pregnancy. Mean age was 29 years (range 23-37). Mean gestational age upon admission was 29 weeks (range 23-36) and 7 of the women were nulliparous. Nine of the 10 patients had subjective symptoms, e.g. headache and/or epigastric pain. All were considered in need of intensive care. Two patients were found to have an abnormal coagulation and liver function. All patients had normal serum creatinine values despite proteinuria. Hypertension was treated with dihydralazine and/or labetalol. Volume substitution was carried out with plasma and albumin. The women could be divided into two groups: 5 patients where progress of the disease despite therapy led to delivery within 24 h, and 5 patients whose diastolic blood pressure could be stabilized around 100 mmHg after treatment and pregnancy could be prolonged by 5-13 days. Common for all patients was a hyperkinetic circulation with an increased cardiac output despite a variety of central pressures. Invasive monitoring of central pressures with a Swan-Ganz catheter demonstrated that the clinical status could be stabilized and the pregnancy prolonged in 5 of the 10 women with severe pre-eclampsia. The variety of the central hemodynamic values illustrates clearly that treatment has to be individualized regarding antihypertensive medication, fluids and diuretics.(ABSTRACT TRUNCATED AT 250 WORDS)

Incorporation of hormone-sensitive lipase into phosphatidylcholine vesicles

Enzymatically active, detergent-solubilized purified hormone-sensitive lipase (HSL) was incorporated into phosphatidylcholine (PC) vesicles, using a detergent-dialysis procedure with small PC vesicles, obtained by sonication, as phospholipid source and CHAPS, a zwitterionic bile-salt derivative, as detergent. Association of enzyme protein with the PC vesicles was verified by floatation in a discontinuous dextran gradient and by gel chromatography. An average of 35% of added HSL was incorporated into the vesicles. The vesicles were shown, by quasi-elastic light scattering and electron microscopy, to have a diameter of approximately 160 nm. The vesicle-associated HSL could be phosphorylated by cyclic AMP-dependent protein kinase. The vesicles were stable, both with regard to enzyme activity and size, for at least 4 days when stored at 4 degrees C. The preparation of detergent-free, vesicle-associated and stable HSL provides new possibilities to study some of its properties, and supports and extends the previous report (Holm, C., Fredrikson, G., and Belfrage, P., J. Biol. Chem. 261, 15659-15661, 1986) which demonstrated the amphiphilic character of HSL.

Evidence that insulin and isoprenaline activate the cGMP-inhibited low-Km cAMP phosphodiesterase in rat fat cells by phosphorylation

Incubation of intact rat fat cells with maximally effective concentrations of insulin (1 nM, 12 min) or isoprenaline (300 nM, 3 min) increased particulate cGMP- and cilostamide-inhibited, low-Km cAMP phosphodiesterase (cAMP-PDE) activity by about 50% and 100%, respectively. In 32P-labeled cells, these agents induced serine 32P-phosphorylation of a 135-kDa particulate protein and, to a variable and lesser extent, a 44-kDa protein, which were selectively immunoprecipitated by anti-cAMP-PDE, as analyzed by SDS/PAGE and autoradiography. In the absence of hormonal stimulation, little phosphorylation was detected (less than 10% of that with the hormones). The two phosphoproteins were identified as cAMP-PDE or a closely related molecule (in the case of the 44-kDa species, perhaps a proteolytic fragment) since (i) amounts of 32P in the immunoprecipitated 135-kDa protein paralleled enzyme inactivation, (ii) prior incubation of the anti-cAMP-PDE with the pure rat or bovine enzyme selectively blocked the immunoprecipitation of the phosphoproteins, (iii) 135- and 44-kDa proteins reacted with the anti-cAMP-PDE on Western immunoblots, and (iv) the two phosphoproteins copurified with cAMP-PDE activity through DEAE-Sephacel chromatography and were isolated by highly selective affinity chromatography on cilostamide-agarose. Thus, in fat cells, catecholamine- and insulin-induced activation of the cAMP-PDE may be mediated via phosphorylation by cAMP-dependent protein kinase and an insulin-activated serine protein kinase, respectively.