Folate improves endothelial function in coronary artery disease: an effect mediated by reduction of intracellular superoxide?

Homocysteine is a risk factor for coronary artery disease (CAD). Folic acid lowers homocysteine and may improve endothelial function in CAD, although the mechanism is unclear. We investigated the effect of folic acid on endothelial function, homocysteine, and oxidative stress in patients with CAD. We also examined the acute effect of 5-methyltetrahydrofolate (5-MTHF), the principal circulating folate, on endothelial function in vivo and on intracellular superoxide in cultured endothelial cells. A randomized crossover study of folic acid (5 mg daily) for 6 weeks was undertaken in 52 patients with CAD. Ten further patients were given intra-arterial 5-MTHF. Endothelial function was assessed by flow-mediated dilatation (FMD). Folic acid increased plasma folate (P<0.001), lowered homocysteine by 19% (P<0.001), and improved FMD (P<0.001). FMD improvement did not correlate with homocysteine reduction. Malondialdehyde and total plasma antioxidant capacity, markers of oxidative stress, were unchanged. 5-MTHF acutely improved FMD (P<0.001) without altering homocysteine (P=0.47). In vitro, 5-MTHF abolished homocysteine-induced intracellular superoxide increase (P<0.001); this effect was also observed with folic acid and tetrahydrobiopterin. Our data support the beneficial effect of folic acid on endothelial function in CAD but suggest that the mechanism is independent of homocysteine. Reduction of intracellular endothelial superoxide may have contributed to the effect.

Cross-reactivity of Epstein-Barr virus-specific immunoglobulin M antibodies with cytomegalovirus antigens containing glycine homopolymers

Timely and reliable detection of acute primary human cytomegalovirus (HCMV) infection is important in prenatal screening programs and for differential diagnosis of infectious mononucleosis-like disease. Enzyme-linked immunosorbent assays (ELISAs) based on HCMV proteins enable the sensitive detection of immunoglobulin M (IgM) antibodies during primary infection. However, concerns have been raised about possible cross-reactivities of the HCMV antigens used for the design of such ELISAs with IgM antibodies induced by Epstein-Barr Virus (EBV). In this study we investigated whether IgM antibodies generated during acute EBV infection reacted with recombinant HCMV antigens. Serum samples from patients with primary EBV infection frequently scored positive when tested in different HCMV IgM ELISAs, irrespective of whether conventional or recombinant antigens were used for the design of the HCMV IgM assays. Such cross-reactive IgM antibodies were found to be directed against short glycine-rich motifs contained within the nonstructural HCMV proteins pUL44 and pUL57. Further analyses revealed that these glycine-rich motifs were major antigenic domains for IgM antibodies induced during HCMV infection. Their deletion from recombinant proteins abrogated reactivity with IgM synthesized during HCMV infection. EBV-induced IgM antibodies that reacted with HCMV antigens showed similar kinetics of reactivity in HCMV- or EBV-specific assays in the course of primary EBV infection, indicating that the two populations of antibodies were highly overlapping. The results demonstrate that primary EBV infection leads to the induction of IgM antibodies that specifically bind to widely used diagnostic antigens of HCMV. This has to be considered in the interpretation of HCMV-specific IgM assays.

The realities of postoperative disability and the carer's burden

Outcome after high-risk, complex neurosurgery for progressive skull base pathology, and its effect on carers, has been examined. Two different outcome measures were used. The Glasgow Outcome Score (GOS) assesses overall social capability and dependence of the patient, while the 36 item short-form health survey (SF-36), a generic quality of life measure, can be compared directly with the general population. Overall outcome using the GOS indicated a favourable outcome for 13 of the 17 patients studied. The SF-36 demonstrated that more than half the patients were functioning at a level below the accepted norm. The reasons for this discrepancy and the validity of outcome scales have been analysed. In addition, the effect upon carers, its relevance to assessment of outcome, and the need to involve potential carers in the process of informed consent was stated. Our conclusions are applicable throughout the surgical specialities, and especially to high-risk complex surgery.

Serological diagnosis of Epstein-Barr virus infection by novel ELISAs based on recombinant capsid antigens p23 and p18

A new pair of Epstein-Barr virus ELISAs (Biotest Anti-EBV VCA IgG and VCA IgM ELISA) was evaluated for usefulness for routine diagnosis of acute EBV infections. The ELISAs are based on two viral capsid antigens (VCA), p23 (BLRF2, full-length) and p18 (BFRF3, carboxy-half), that are combined by autologous gene fusion. In total, 179 sera were tested in direct comparison with classical VCA immunofluorescence assays (IFA). With the help of clinical data and additional reference serology, i.e., heterophile antibodies, anti-EA IgG (IFA) and anti-EBNA-1 IgG (ELISA), the patients were divided into the following categories: seronegatives (46), acute primary infections (67), previous infections (39), suspected reactivations (20) and constellations with intermediate serological patterns (7). The VCA IgG and VCA IgM ELISAs showed overall agreement to IFA of 95.0% and 94.4%, respectively. The calculated analytical performance (sensitivity; specificity) of VCA IgG and VCA IgM was 94.0%; 97.8% and 97.1%; 96.5%, respectively. A certain delay in seroconversion of anti-p23-p18 IgG may account for a significant difference in sensitivity of the VCA IgG ELISA between primary (88.4%) and previous infections (100%). In summary, the new recombinant VCA ELISAs yielded good correlation to VCA IFA and in combination with EBNA-1 IgG allow rapid, sensitive, and specific diagnosis of infectious mononucleosis or EBV immune status in general.

Patient-assessed outcomes after excision of acoustic neuroma: postoperative symptoms and quality of life

OBJECT

The aim of this study was to assess whether outcomes from excision of acoustic neuroma vary among patients and have a material impact on their quality of life (QOL).

METHODS

A questionnaire concerning postoperative symptoms and the Short Form 36 (SF-36) QOL instrument were mailed to 97 consecutive patients who had undergone acoustic neuroma surgery via the translabyrinthine approach. The survey response rate was 78% and the symptomatology was consistent with other reports, supporting the representativeness of the sample. The respondents' QOL was rated significantly below published norms and their work capacity was reportedly reduced. Specifically, the following SF-36 dimensions were reduced: physical functioning and role-physical, together with vitality, general health, and social functioning. Greater numbers of postoperative symptoms and larger tumors were associated with a worse rating of physical functioning. More severe balance problems were associated with lower ratings of social functioning. The disparity between the patient's self-estimate and self-measurement and the clinician's assessment of the patient's facial functioning raises doubts about the validity of subjective reports and assessment.

CONCLUSIONS

The present study supports the use of generic QOL measures to assess outcome and to draw comparisons between different populations.

Gender-related plasma levels of progesterone, interleukin-8 and interleukin-10 during and after cardiopulmonary bypass in infants and children

BACKGROUND

It is known that proinflammatory and anti-inflammatory cytokines are released during and after cardiopulmonary bypass (CPB) in infants and children. Sex steroids are known to have immunomodulatory functions, and release of the anti-inflammatory cytokine IL-10 is stimulated by progesterone in vitro. The purpose of the present study was to investigate the plasma levels of progesterone, IL-8 (proinflammatory cytokine) and IL-10, and to relate them to sex and postoperative morbidity.

METHOD

Eighteen infants and children (eight female) undergoing CPB were prospectively studied. Plasma levels of progesterone, IL-8 and IL-10 were determined before and 10 min after the start of CPB, and immediately after CPB; and 6 h, 24 h, 3 days and 7 days postoperatively. Organ dysfunction was identified on the basis of arbitrarily defined criteria.

RESULTS

After CPB, all patients showed significant increases in plasma levels of progesterone, IL-8 and IL-10. Plasma levels of IL-10 were significantly higher in female patients, except for during the immediate postoperative period. According to the criteria used, six out of 10 male patients, but none of the female patients developed multiple organ dysfunction (MOD).

CONCLUSION

The present study shows that CPB induces a significant and marked increase in plasma levels of progesterone in infants and children. Studies of administration of progesterone-blocking substances to male and female animals may help to elucidate the roles of sex and progesterone in the setting of CBP.

A snapshot of a transition state analogue of a novel thermophilic esterase belonging to the subfamily of mammalian hormone-sensitive lipase

EST2 is a novel thermophilic carboxylesterase, isolated and cloned from Alicyclobacillus (formerly Bacillus) acidocaldarius, which optimally hydrolyses esters with acyl chain lengths of six to eight carbon atoms at 70 degrees C. On the basis of the amino acid sequence homology, it has been classified as a member of the mammalian hormone-sensitive lipase (HSL) subfamily. The crystal structure of EST2, complexed with a sulphonyl derivative, has been determined at 2.6 A resolution by a multiple wavelength anomalous diffraction experiment on a seleno-methionine derivative. EST2 presents a canonical alpha/beta hydrolase core, shielded at the C-terminal side by a cap region built up of five helices. It contains the lipase-like catalytic triad, Ser155, His282 and Asp252, whereby the nucleophile is covalently modified. This allows an unambiguous view of the putative active site of EST2, detecting the oxyanion hole, in whose formation the amino acid sequence motif His81-Gly82-Gly83-Gly84 is involved, and the hydrophobic binding pocket for the acyl chain. The structural model here reported provides the first example of a transition state analogue of an esterase/lipase belonging to the HSL group, thus affording useful information for the design of medical inhibitors. Moreover, as the first X-ray structure of a thermophilic carboxylesterase, the comparison with its mesophilic homologue, the Brefeldin A esterase (BFAE) from Bacillus subtilis, allows the identification of putative determinants of thermal stability.

Differential expression of heat shock protein 70 (hsp70) in human monocytes rendered apoptotic by IL-4 or serum deprivation

Apoptosis of monocytes is regulated by the balance between pro- and antiapoptotic triggers and pathways and may strongly influence inflammatory disorders. The major heat shock protein, hsp70, is an effective inhibitor of apoptosis in lymphocytic and monocytic tumor cell lines, but the implications in the regulation of apoptosis of freshly isolated human monocytes have not been elucidated. In this study, we examined whether two different triggers of monocyte apoptosis, serum deprivation and IL-4, respectively, altered hsp70 expression and whether expression levels correlated with monocyte survival. Monocyte apoptosis was determined quantitatively by flow cytometry detecting annexin V binding or nuclear stainability with propidium iodide (PI). Hsp70 expression was analyzed by semiquantitative RT-PCR and immunoblotting. Exposing monocytes to heat shock (47 degrees C, 20 min) induced a rapid and marked upregulation of hsp70 without evoking injury or apoptosis, suggesting that hsp70 conferred protection and survival. In accordance, when monocytes were rendered apoptotic by serum deprivation, a drastic downregulation of hsp70 occurred, which was accompanied by a reduced synthesis of the constitutive family member hsc70. However, induction of monocyte apoptosis by IL-4 increased hsp70 expression in a concentration and time-dependent fashion. A neutralizing antibody against IL-4 abolished hsp70 expression and apoptosis induction after IL-4 treatment and so excluded indirect effects. LPS rescued monocytes from apoptosis but did not alter hsp70 formation significantly. These findings suggest that, in monocytes, distinct apoptotic triggers induce different responses of hsp70 so that this molecule does not exert protection against cell death directly or in general.

Regulation of mesangial cell apoptosis and proliferation by intracellular Ca(2+) signals

BACKGROUND

In inflammatory glomerular diseases, proliferation, as well as apoptosis of mesangial cells (MCs), has been shown histomorphologically. Both processes may regulate the cellular content of the mesangium by closely influencing each other. In the present study, we examined whether the cytoplasmic free Ca(2+) concentration [Ca(2+)](i) is involved as a key second messenger in the regulation of proliferative and apoptotic events.

METHODS

Thapsigargin, an inhibitor of the endoplasmic Ca(2+)-Mg(2+)-ATPase, was used as a test substance to investigate the role of [Ca(2+)](i) in signaling MC apoptosis and growth in vitro. Apoptosis was determined by nuclear chromatin staining with Hoechst 33258, by a [3H]-thymidine-based DNA fragmentation assay or by flow cytometry detecting binding of FITC-conjugated annexin V. Proliferation was measured by [3H]-thymidine incorporation into acid-precipitable material and corroborated by cell counting.

RESULTS

Thapsigargin significantly induced apoptosis and inhibited proliferation dose dependently in nanomolar concentrations without evoking necrotic damage when administered not longer than 12 hours. Significant apoptosis was measurable after a six-hour treatment of MCs with thapsigargin. Determination of [Ca(2+)](i) by fura-2-dependent spectrofluorometry showed that thapsigargin was able to induce prolonged [Ca(2+)](i) rises that could be prevented by preincubation with the intracellular Ca(2+) chelator 1, 2-bis(2-aminophenoxy)-ethane-N,N,N', N'-tetra-acetic acid (BAPTA) acetomethyl ester (AM). BAPTA had no influence on MC viability but reversed thapsigargin-induced apoptosis to control levels. After thapsigargin treatment (100 nmol/L, 12 hours), apoptotic MCs had a significantly higher [Ca(2+)](i) of 251 +/- 25 nmol/L (N = 41) as compared with MCs that were not or not yet apoptotic ([Ca(2+)](i) of 116 +/- 20 nmol/L, N = 26, P < 0,05). Platelet-derived growth factor (PDGF), a well-characterized growth factor for MCs, reversed the effects of thapsigargin on proliferation and apoptosis in a similar fashion as BAPTA. PDGF acutely stimulated increases of [Ca2+]i but abolished thapsigargin-dependent, but not angiotensin II- or ATP-induced Ca(2+) rises when administered during a 12-hour preincubation.

CONCLUSIONS

Our data suggest that a sustained increase of [Ca(2+)](i) may serve as a signal to trigger MC apoptosis. Growth factors such as PDGF can abolish apoptosis induced by elevations of [Ca(2+)](i) by altering intracellular Ca(2+) signaling.

Neutrophil superoxide anion--generating capacity, endothelial function and oxidative stress in chronic heart failure: effects of short- and long-term vitamin C therapy

OBJECTIVES

First, we sought to study the effects of short- and long-term vitamin C therapy on oxidative stress and endothelial dysfunction in chronic heart failure (CHF), and second, we sought to investigate the role of neutrophils as a cause of oxidative stress in CHF.

BACKGROUND

Oxidative stress may contribute to endothelial dysfunction in CHF. Vitamin C ameliorates endothelial dysfunction in CHF, presumably by reducing oxidative stress, but this is unproven.

METHODS

We studied 55 patients with CHF (ischemic and nonischemic etiologies) and 15 control subjects. Flow-mediated dilation (FMD) in the brachial artery was measured by ultrasound wall-tracking, neutrophil superoxide anion (O2-) generation by lucigenin-enhanced chemiluminescence and oxidative stress by measurement of free radicals (FRs) in venous blood using electron paramagnetic resonance (EPR) spectroscopy and plasma thiobarbituric acid reactive substances (TBARS). Measurements were performed at baseline in all subjects. The effects of short-term (intravenous) and long-term (oral) vitamin C therapy versus placebo were tested in patients with nonischemic CHF.

RESULTS

At baseline, FRs were higher in patients with CHF than in control subjects (p < 0.01), TBARS were greater (p < 0.005), neutrophil O2- -generating capacity was enhanced (p < 0.005) and FMD was lower (p < 0.0001). Compared with placebo, short-term vitamin C therapy reduced FR levels (p < 0.05), tended to reduce TBARS and increased FMD (p < 0.05), but did not affect neutrophil O2- -generating capacity. Long-term vitamin C therapy reduced FR levels (p < 0.05), reduced TBARS (p < 0.05) and improved FMD (p < 0.05), but also reduced neutrophil O2- -generating capacity (p < 0.05). Endothelial dysfunction was not related to oxidative stress, and improvements in FMD with vitamin C therapy did not relate to reductions in oxidative stress.

CONCLUSIONS

Oxidative stress is increased in ischemic and nonischemic CHF, and neutrophils may be an important cause. Vitamin C reduces oxidative stress, increases FMD and, when given long term, decreases neutrophil O2- generation, but the lack of a correlation between changes in endothelial function and oxidative stress with vitamin C implies possible additional non-antioxidant benefits of vitamin C.

Pax3 is required for enteric ganglia formation and functions with Sox10 to modulate expression of c-ret

Hirschsprung disease and Waardenburg syndrome are human genetic diseases characterized by distinct neural crest defects. Patients with Hirschsprung disease suffer from gastrointestinal motility disorders, whereas Waardenburg syndrome consists of defective melanocyte function, deafness, and craniofacial abnormalities. Mutations responsible for Hirschsprung disease and Waardenburg syndrome have been identified, and some patients have been described with characteristics of both disorders. Here, we demonstrate that PAX3, which is often mutated in Waardenburg syndrome, is required for normal enteric ganglia formation. Pax3 can bind to and activate expression of the c-RET gene, which is often mutated in Hirschsprung disease. Pax3 functions with Sox10 to activate transcription of c-RET, and SOX10 mutations result in Waardenburg-Hirschsprung syndrome. Thus, Pax3, Sox10, and c-Ret are components of a neural crest development pathway, and interruption of this pathway at various stages results in neural crest-related human genetic syndromes.

Structural evidence for evolution of the beta/alpha barrel scaffold by gene duplication and fusion

The atomic structures of two proteins in the histidine biosynthesis pathway consist of beta/alpha barrels with a twofold repeat pattern. It is likely that these proteins evolved by twofold gene duplication and gene fusion from a common half-barrel ancestor. These ancestral domains are not visible as independent domains in the extant proteins but can be inferred from a combination of sequence and structural analysis. The detection of subdomain structures may be useful in efforts to search genome sequences for functionally and structurally related proteins.

Directed evolution of an enantioselective lipase

BACKGROUND

The biocatalytic production of enantiopure compounds is of steadily increasing importance to the chemical and biotechnological industry. In most cases, however, it is impossible to identify an enzyme that possesses the desired enantioselectivity. Therefore, there is a strong need to create by molecular biological methods novel enzymes which display high enantioselectivity.

RESULTS

A bacterial lipase from Pseudomonas aeruginosa (PAL) was evolved to catalyze with high enantioselectivity the hydrolysis of the chiral model substrate 2-methyldecanoic acid p-nitrophenyl ester. Successive rounds of random mutagenesis by ep-PCR and saturation mutagenesis resulted in an increase in enantioselectivity from E=1.1 for the wild-type enzyme to E=25.8 for the best variant which carried five amino acid substitutions. The recently solved three-dimensional structure of PAL allowed us to analyze the structural consequences of these substitutions.

CONCLUSIONS

A highly enantioselective lipase was created by increasing the flexibility of distinct loops of the enzyme. Our results demonstrate that enantioselective enzymes can be created by directed evolution, thereby opening up a large area of novel applications in biotechnology.

Generation of monoclonal antibodies directed against the immunogenic glycoprotein K8.1 of human herpesvirus 8

Human Herpesvirus 8 (HHV-8) is clearly associated with Kaposi's sarcoma (KS), body cavity-based lymphomas (BCBL), and certain forms of multifocal Castleman's disease (MCD). It appears to be the sexually transmissible agent involved in the development of AIDS-associated KS. HHV-8 genomes are invariably present in BCBL-derived cell lines where lytic replication of the virus can be induced by phorbol esters (PE). First-generation HHV-8 serological assays were based on these cell lines. More recently, several genes encoding HHV-8 antigens have been identified. One of the most reactive antigens is encoded by HHV-8 open reading frame K8.1. Although K8.1 does not exhibit overt sequence homology to any other known gene, it is likely to be analogous to gp220/350 of Epstein-Barr or gp150 of murine herpesvirus-68, virion-envelope glycoproteins involved in target cell recognition. Mice were immunized with purified GST-K8.1 fusion protein expressed in E. coli. After fusion of murine plasma cells with the myeloma cell line P3-X63-Ag8. monoclonal antibodies (MAbs) were generated, which are specifically directed against K8.1 protein. The binding site for each MAb was identified by deletion mutant analysis using recombinant GST-K8.1 mutants and K8.1-specific peptides. Without exception, the epitopes recognized by these MAbs were located within the N-terminal part of the protein [amino acids (aa) 29 to 80], thus identifying a highly immunogenic region. These antibodies will not only be useful tools for HHV-8 diagnostics, but will also facilitate the analysis of K8.1 function.

Expression of CHL1 and L1 by neurons and glia following sciatic nerve and dorsal root injury

Cell adhesion molecules (CAMs), particularly L1, are important for axonal growth on Schwann cells in vitro. We have used in situ hybridization to study the expression of mRNAs for L1 and its close homologue CHL1, by neurons regenerating their axons in vivo, and have compared CAM expression with that of GAP-43. Adult rat sciatic nerves were crushed (allowing functional regeneration), or cut and ligated to maintain axonal sprouting but prevent reconnection with targets. In other animals lumbar dorsal roots were transected to produce slow regeneration of the central axons of sensory neurons. In unoperated animals L1 and CHL1 mRNAs were expressed at moderate levels by small- to medium-sized sensory neurons and L1 mRNA was expressed at moderate levels by motor neurons. Many large sensory neurons expressed neither L1 nor CHL1 mRNAs and motor neurons expressed little or no CHL1 mRNA. Neither motor nor sensory neurons showed any obvious upregulation of L1 mRNA after axotomy. Increased CHL1 mRNA was found in motor neurons and small- to medium-sized sensory neurons 3 days to 2 weeks following sciatic nerve crush, declining toward control levels by 5 weeks when regeneration was complete. Cut and ligation injuries caused a prolonged upregulation of CHL1 mRNA (and GAP-43 mRNA), indicating that reconnection with target tissues may be required to signal the return to control levels. Large sensory neurons did not upregulate CHL1 mRNA after axotomy and thus regenerated within the sciatic nerve without producing CHL1 or L1. Dorsal root injuries caused a modest, slow upregulation of CHL1 mRNA by some sensory neurons. CHL1 mRNA was also upregulated by many presumptive Schwann cells in injured nerves and by some satellite cells around large sensory neurons after sciatic nerve injuries and was transiently upregulated by some astrocytes in the degenerating dorsal columns after dorsal rhizotomy.

[Long-term problems after kidney transplantations]

Allogenic kidney transplantation is a widely established treatment option for patients with end-stage renal disease to gain independency from dialysis and recovery of excretory and hormonal functions. Transplantation is superior to dialysis with respect to quality of life, morbidity and mortality. Improvements in one-year graft survival have become evident during the last decades, but long-term outcome is not yet satisfying. The most common form of late transplant failure is chronic rejection or chronic allograft nephropathy, and as a consequence of higher ages of transplant recipients death of patients with functioning grafts. The histological hallmark of chronic rejection is intimal thickening of small arteries and arterioles, but the involved pathomechanisms are not well understood. Strict normalization of blood pressure and hyperlipidemia by drugs aims to prevent vascular alterations of chronic allograft nephropathy. In addition, in this overview some other late complications of renal transplant recipients are addressed which are associated to chronic immunosuppression, such as viral or malignant diseases.

Migration of cardiac neural crest cells in Splotch embryos

Pax3 encodes a transcription factor expressed during mid-gestation in the region of the dorsal neural tube that gives rise to migrating neural crest populations. In the absence of Pax3, both humans and mice develop with neural crest defects. Homozygous Splotch embryos that lack Pax3 die by embryonic day 13.5 with cardiac defects that resemble those induced by neural crest ablation in chick models. This has led to the hypothesis that Pax3 is required for cardiac neural crest migration. However, cardiac derivatives of Pax3-expressing precursor cells have not been previously defined, and Pax3-expressing cells within the heart have not been well demonstrated. Hence, the precise role of Pax3 during cardiac development remains unclear. Here, we use a Cre-lox method to fate map Pax3-expressing neural crest precursors to the cardiac outflow tract. We show that although Pax3 itself is extinguished prior to neural crest populating the heart, derivatives of these precursors contribute to the aorticopulmonary septum. We further show that neural crest cells are found in the outflow tract of Splotch embryos, albeit in reduced numbers. This indicates that contrary to prior reports, Pax3 is not required for cardiac neural crest migration. Using a neural tube explant culture assay, we demonstrate that neural crest cells from Splotch embryos show normal rates of proliferation but altered migratory characteristics. These studies suggest that Pax3 is required for fine tuning the migratory behavior of the cardiac neural crest cells while it is not essential for neural crest migration.

Prenatal diagnosis of an aortico-left ventricular tunnel

Aortico-left ventricular tunnel is a rare abnormal communication between the ascending aorta and the left ventricle. Early diagnosis and prompt surgical repair prevent congestive heart failure or consecutive valvular insufficiency. However, in utero diagnosis of this heart malformation has been rarely described and none of those children survived. We report on a case of aortico-left ventricular tunnel detected at 32 weeks' gestation with a favourable outcome after surgical repair at three months of age.

Unusual electrocardiogram findings in a preterm infant after fetal tachycardia with hydrops fetalis treated with flecainide

Fetal tachycardia and signs of hydrops fetalis were diagnosed at 29 weeks of gestation. The heart rate normalized by combined treatment with digoxin and flecainide and was followed by improvement of the hydrops. Premature labor led to delivery at 33 weeks of gestation. The newborn infant showed mild respiratory distress and was in a hemodynamically stable condition. Marked QT segment anomalies on the electrocardiogram during the first postnatal days resolved completely within 3 weeks. They were unlikely to be attributable to myocarditis or myocardial infarction. We speculate that these anomalies were caused by the maternal flecainide therapy.

Plasminogen activator inhibitor 1. Structure of the native serpin, comparison to its other conformers and implications for serpin inactivation

The crystal structure of a constitutively active multiple site mutant of plasminogen activator inhibitor 1 (PAI-1) was determined and refined at a resolution of 2.7 A. The present structure comprises a dimer of two crystallographically independent PAI-1 molecules that pack by association of the residues P6 to P3 of the reactive centre loop of one molecule (A) with the edge of the main beta-sheet A of the other molecule (B).Thus, the reactive centre loop is ordered for molecule A by crystal packing forces, while for molecule B it is unconstrained by crystal packing contacts and is disordered. The overall structure of active PAI-1 is similar to the structures of other active inhibitory serpins exhibiting as the major secondary structural feature a five-stranded beta-sheet A and an intact proteinase-binding loop protruding from the one end of the elongated molecule. No preinsertion of the reactive centre loop is observed in this structure.A comparison of the present structure with the previously determined crystal structures of PAI-1 in its alternative conformations reveals that, upon cleavage of an intact form of PAI-1 or formation of latent PAI-1, the well-characterised rearrangements of the serpin secondary structural elements are accompanied by dramatic and partly unexpected conformational changes of helical and loop structures proximal to beta-sheet A. The present structure explains the stabilising effects of the mutated residues, reveals the structural cause for the observed spectroscopic differences between active and latent PAI-1, and provides new insights into possible mechanisms of stabilisation by its natural binding partner, vitronectin.

Coronary microvascular endothelial cell redox state in left ventricular hypertrophy : the role of angiotensin II

Left ventricular hypertrophy (LVH) is associated with elevated plasma angiotensin II (Ang II) levels and endothelial dysfunction. The relationship between Ang II and endothelial dysfunction remains unknown, however, but it may involve an alteration in endothelial cell redox state. We therefore investigated the effect of Ang II on NADH/NADPH oxidase-mediated superoxide anion (O(2)(-)) production by cultured guinea pig coronary microvascular endothelial cells (CMVEs) and CMVEs freshly isolated from a guinea pig, pressure-overload model of LVH. Lucigenin chemiluminescence was used to measure O(2)(-) production in the particulate fraction of CMVE lysates. In cultured cells, incubation with Ang II (0.1 nmol/L to 1 micromol/L for 18 hours) resulted in significant (P<0.01) increases in both NADH- and NADPH-dependent O(2)(-) production, with a peak effect at 1 nmol/L. The latter was significantly (P<0.01) inhibited by the AT(1) receptor antagonist losartan (1 micromol/L for 18 hours). In contrast, the O(2)(-) response to Ang II (0.1 nmol/L to 1 micromol/L for 18 hours) was largely unaffected by concomitant exposure to the AT(2) antagonist PD 123319 (1 micromol/L). In freshly isolated CMVEs from nonoperated animals, NADH- and NADPH-dependent O(2)(-) production was not different from that in sham-operated animals but was significantly (P<0.05) elevated in the aortic-banded animals. Plasma Ang II levels were significantly (P<0.001) elevated in the aortic-banded (1.25+/-0.12 microg/L, n=12) compared with sham-operated animals (0.63+/-0.06 microg/L, n=12). These data suggest that the endothelial dysfunction associated with LVH may be due, at least in part, to the Ang II-induced upregulation of NADH/NADPH oxidase-dependent O(2)(-) production.

Homocysteine and endothelial dysfunction: a link with cardiovascular disease

The nature of the link between homocysteine and cardiovascular disease has not yet been clearly established. Impaired endothelium-independent vasodilatation is an early feature of vascular disease. In human studies, methionine loading, which acutely elevates plasma homocysteine, induces endothelial dysfunction. Folate therapy, which lowers homocysteine, enhances endothelial function. This is consistent with, but not proof of, homocysteine toxicity to endothelium in vivo. Homocysteine, in high concentration, can induce endothelial dysfunction in vitro. This is accompanied by increased superoxide production, which when inhibited, restores normal endothelial function. These observations suggest that homocysteine may induce vascular endothelial dysfunction by a mechanism involving reactive oxygen species.