Learning from mistakes when reporting urgent and emergency vascular studies.

The majority of out-of-hours cases relate to neurological, chest, and gastrointestinal pathologies with acute vascular cases being encountered less commonly. Trainees and exposure of non-vascular/interventional radiology (IR) consultants to angiographic imaging is often limited in working hours and this may lead to reporting on-call cases outside of normal daytime practice. In a recent local review, a number on-call vascular studies were found to contain a number of vascular-related discrepancies. Vascular reporting is a complex subspecialty, which comprises many clear diagnoses (large vessel occlusions, large vessel aneurysms, or dissections); however, also several subtle and complex abnormalities. These more subtle abnormalities, at times, require dedicated vascular specialist review to ensure subtle findings are communicated appropriately to the clinical team. The recent increased complexity of endovascular treatments and their complications has also provided further challenge for the non-specialist reporter. Similarly, improved imaging techniques have allowed for non-obvious but significant findings that may require urgent management, such as small aneurysms and dissection flaps. We will review a range of key vascular findings that demonstrate learning opportunities, particularly within the acute and on-call settings. These will include gastrointestinal haemorrhage, subtle aortic pathologies, head and neck vascular emergencies, small to mid-sized vessel injuries and imaging of post-procedural complications. Educational hints and tips will be provided to enable learning from mistakes encountered by trainees and non-vascular specialist radiologists in the on-call or urgent reporting settings, and these will be reviewed with reference to the literature.

Spatial ecology of the Giant Sea Bass, Stereolepis gigas, in a southern California kelp forest as determined by acoustic telemetry.

The fisheries history of the Giant Sea Bass, Stereolepis gigas (Telostei: Polyprionidae), is closely linked to its spatial ecology. Its overharvest is directly associated with formation of spatially distinct spawning aggregations during summer, while its subsequent recovery is hypothesized to be the result of spatially explicit gear restrictions. Understanding the spatial ecology of Giant Sea Bass is a key part of efforts to assess contemporary threats such as commercial harvest and incidental catch by recreational fisheries. In this study, we used acoustic telemetry to characterize Giant Sea Bass space use in the La Jolla kelp forest using an acoustic array that encompasses two marine protected areas (MPAs) and heavily trafficked recreational fishing grounds. Five of the seven fish we tagged remained in the La Jolla array for at least 6 months. Two fish were resident across multiple years, with one fish consistently detected for 4 years. Only one fish was detected in the broader network of regional acoustic receivers, moving north approximately 8 km to Del Mar. Most tagged fish had home ranges and core use areas indicating they spend considerable time outside MPAs, particularly in areas with high recreational fishing activity. During spawning season we detected fish less frequently in the La Jolla array and recorded higher movement rates. While the current MPA network in La Jolla by no means offers complete protection to this fish, it does appear to support long-term persistence of some individuals in a region of exceptionally high recreational fishing pressure.

Pre-operative sildenafil and pulmonary endothelial-related complications following cardiopulmonary bypass: a randomised trial in children undergoing cardiac surgery.

In a randomised trial, we compared the effects of oral sildenafil (0.5 mg.kg(-1) ) and placebo, administered the day before cardiac surgery, in 24 children. In sildenafil vs placebo patients, pre-cardiopulmonary bypass median (IQR [range]) cyclic-guanosine-monophosphate was not significantly different (29.9 (2.1-208.1 [0.5-391.5]) vs 5.2 (0.3-54.6 [0-628.9]) pmol.ml(-1) , respectively). Post-cardiopulmonary bypass, nitrate/nitrite levels were also not significantly different (0.7 (0-8.0 [0-142.8]) vs 0 (0-2.7 [0-52.7]) µM, respectively). Postoperatively, mean (SD) pulmonary vascular resistance (2.64 (2.28) vs 1.90 (1.12) WU.m(-2) , respectively and oxygenation index (5.29 (4.60) vs 3.38 (2.54), respectively) remained unchanged, whilst oxygen delivery (57.18 (21.24) vs 74.13 (35.46) ml.min(-1) .m(-2) , respectively) and bi-ventricular systolic function (left ventricle 3.78 (0.94) vs 4.55 (1.08) cm.s(-1) , respectively; p=0.002; right ventricle 6.93 (1.47) vs 8.09 (2.25) cm.s(-1) , respectively; p<0.001) were significantly reduced in the sildenafil group. In this trial, pre-operative sildenafil did not affect postoperative pulmonary vascular resistance. There was, however, a negative impact on ventricular function and oxygenation.

Expression of TGF beta in the placental bed is not altered in sporadic miscarriage.

Extravillous trophoblast invasion of uterine stroma and spiral arteries (SA) is essential for normal pregnancy and is reduced in preeclampsia and late miscarriage. The control mechanisms are not understood, but transforming growth factor-beta (TGF-beta) may be a candidate. Placental and placental bed biopsies were obtained from early (8(+0)-12(+6) weeks) euploid miscarriages (n = 10), early aneuploid miscarriages (n = 10), late (13(+0)-19(+6) weeks) euploid miscarriages (n = 10) and controls of the same gestation (n = 20). Frozen sections were immunostained for TGF-beta1, 2 and 3. Immunoreactivity of trophoblast and uterine cell populations was assessed semi-quantitatively. TGF-beta1 immunolocalization was limited to extracellular matrix in cytotrophoblast islands and cytotrophoblast shell, perivascular fibrinoid and interstitial trophoblast and did not differ in miscarriage compared with controls. TGF-beta2 was expressed additionally in endovascular trophoblast and multinucleate trophoblast giant cells. There was no aberrant TGF-beta2 immunolocalization in late miscarriage, but TGF-beta2 immunoreactivity was increased in extracellular matrix in cytotrophoblast islands in early miscarriage. TGF-beta3 was absent from all cell populations. Stromal and extravillous trophoblast TGF-beta2 immunolocalization suggests a more important role in trophoblast invasion than TGF-beta1, but neither isoform was altered in miscarriage. Altered TGF-beta localization is therefore unlikely to play a role in abnormal trophoblast invasion and SA transformation in miscarriage.

Effect of cryopreservation on human cytotrophoblast cells in culture: hCG and PALP production.

Term villous cytotrophoblasts differentiate into syncytiotrophoblast during culture exhibiting characteristic changes in cellular morphology and protein expression profiles. Measurement of human chorionic gonadotropin (hCG) and placental alkaline phospatase (PALP) is often used to assess viability and syncytialisation of cultured cells. The objective of this study was to assess the effect of cryopreservation of isolated cytotrophoblasts on the expression hCG and PALP by cells during subsequent culture. Villous cytotrophoblasts isolated from term placentae from uncomplicated pregnancies were either cultured immediately after isolation or were cryopreserved (liquid nitrogen) prior to culture. Cells were cultured in identical conditions (5% CO(2) in air) for 96 h. Protein and DNA content of cells and HCG and PALP levels in culture medium were measured at 24 h intervals. Cryopreservation had no significant effect on the protein or DNA content of cultured cells but hCG levels in culture medium were significantly reduced after 72 h (P=0.025) compared to cultures of fresh cells. PALP levels were unchanged. Cryopreservation of cytotrophoblast cells prior to culture resulted in a decrease in basal secretion of hCG possibly caused by a failure or delay in the morphological and functional differentiation of cells.

Smartphone speech-to-text applications for communication with profoundly deaf patients.

OBJECTIVE: Visual communication aids, such as handwriting or typing, are often used to communicate with deaf patients in the clinic. This study aimed to establish the feasibility of communicating through smartphone speech recognition software compared with writing or typing. METHOD: Thirty doctors and medical students were timed writing, typing and dictating a standard set of six sentences appropriate for a post-operative consultation, and the results were assessed for accuracy and legibility. RESULTS: The mean time for smartphone dictation (17.8 seconds, 95 per cent confidence interval = 17.0-18.7) was significantly faster than writing (59.2 seconds, 95 per cent confidence interval = 56.6-61.7) or typing (44 seconds, 95 per cent confidence interval = 41.0-47.1) (p < 0.001). Speech recognition was slightly less accurate, but accuracy increased with time spent dictating. CONCLUSION: Smartphone dictation is a feasible alternative to typing and handwriting. Slow speech may improve accuracy. Early clinical experience has been promising.

Activation of bee venom phospholipase A2 by oleoyl imidazolide produces a thiol- and proteinase-resistant conformation.

Assay methods for bee venom phospholipase A2 are presented which respond to different aspects of enzymic behaviour and which allow basal activity, fatty acid activation and acyl-group activation to be distinguished. The stability of the enzyme to thiols and proteinases is dramatically increased by activation with the selective acylating agent, oleoyl imidazolide. These results support the model of activation by conformation change. Limited-fixation studies indicate that enzyme conformation is determined by interaction with the substrate. The oleoyl-enzyme is partially inactivated by trypsin, but its electrophoretic mobility is unchanged. This protective effect is highly selective and only one other component of the venom is protected against trypsin by oleoyl imidazolide. Combination of trypsin and thiol treatment produces a large fragment of the activated enzyme which could be used for structural studies of the activation site.

Priming and remodelling of human placental bed spiral arteries during pregnancy--a review.

It is now well known that in order to establish human hemochorial placentation and to provide a progressive increase in blood supply to the growing fetus, the uterine spiral arteries must undergo considerable alterations. This physiological modification is thought to be brought about by the interaction of invasive cytotrophoblast with the spiral artery vessel wall. Despite intensive research our understanding of the mechanisms that control human trophoblast invasion in normal, let alone abnormal pregnancy, are still poorly understood. This is partly due to difficulties in obtaining "true" placental bed biopsies and most investigators have relied on in vitro models of trophoblast invasion. Clearly interpretation of such studies must be tempered with a degree of caution. This review outlines why the placental bed is important, how we can sample and study it, what morphology actually occurs in the placental bed spiral arteries during pregnancy and then briefly summarise the findings on the placental bed in pre-eclampsia.

Dissolved oxygen concentration in culture medium: assumptions and pitfalls.

Oxygen is a key factor in the regulation of cytotrophoblast differentiation, proliferation and invasion in early pregnancy. Abnormalities in oxygen concentration have also been linked to a number of pregnancy disorders. Cell culture models have been used to study the effect of oxygen on cytotrophoblast behaviour in vitro, however, there is often little or no validation of oxygen levels in these cell culture systems. In this study, dissolved oxygen levels in culture medium maintained in standard culture conditions (18% O(2)) measured 18%. On transfer to a low oxygen environment (2% O(2)), oxygen levels decreased to 6-8% after 4h and reached 2% only after 24h in culture. Culture medium pre-gassed with nitrogen to remove dissolved oxygen quickly absorbed oxygen when exposed to ambient air during dispensing and required further incubation in a 2% oxygen environment before dissolved oxygen levels equilibrated to 2%. Thus, cultured cells placed in a low oxygen environment would be exposed to varying levels of oxygen before the desired level of oxygen exposure is reached. This study highlights the importance of validation of oxygen levels and potential problems associated with in vitro studies on the regulatory effects of oxygen.

Heme oxygenase expression in cultured human trophoblast cells during in vitro differentiation: effects of hypoxia.

Heme oxygenases (HO-1 and HO-2) are responsible for the production of carbon monoxide, a vasodilator. HO is important in controlling placental blood flow and expression can be sensitive to oxygen. We previously reported a reduction in HO-2 expression in placentae obtained from patients with pre-eclampsia or living at high altitude, both associated with placental hypoxia. Thus we hypothesized that HO expression in cultured trophoblasts would be altered by exposure to hypoxia. HO-1 and HO-2 expression was assessed in trophoblast cell cultures following exposure to different oxygen environments. Western blot analyses showed that HO-1 expression in syncytiotrophoblast was significantly lower than in cytotrophoblasts in standard conditions (p < 0.05). There was no difference in HO-1 expression in cytotrophoblasts transferred to 2% O2 for various times. However, exposure of syncytiotrophoblast cultures to hypoxia for 12 h resulted in a significant reduction in HO-1 expression (p < 0.05). HO-2 expression was not affected by exposure to hypoxia in either cytotrophoblast or syncytiotrophoblast cultures. Possible interpretations of these findings are that chronic hypoxia alone is not responsible for reduced HO-2 expression or a much longer exposure to chronic hypoxia (perhaps months) is required. This study also reinforces the complexities of HO regulation by oxygen.

Alphafetoprotein and alphafetoprotein receptor expression in the normal human placenta at term.

Alphafetoprotein (AFP) is detectable in maternal serum from around six weeks of gestation and is synthesised by the yolk sac and the fetal liver. The role of the placenta in the transport and possible synthesis of AFP is uncertain. The aim of this study was to investigate placental expression of AFP and the AFP receptor in uncomplicated pregnancies at term. Immunohistochemistry and Western blotting clearly demonstrated the presence of AFP in villous tissue at term. However, evidence of AFP mRNA expression or synthesis of AFP was not found following reverse transcription polymerase chain reaction of total RNA isolated from villous tissue and trophoblast cell cultures. The presence of a cell surface receptor for AFP in placental villous tissue, identified by immunohistochemistry and Western blotting, suggests a possible receptor-mediated mechanism for placental transport of AFP while the patterns of expression of AFP and its receptor may indicate a possible route by which AFP is transported across the placenta between the fetal and maternal circulations. These findings demonstrate that the placenta does not synthesise AFP at term and that the presence of AFP in the placenta is a reflection of transplacental transport of AFP possibly via a receptor-mediated mechanism.

Increased nitrotyrosine in the diabetic placenta: evidence for oxidative stress.

OBJECTIVE: To evaluate the presence of nitrotyrosine (NT) residues in placental villous tissue of diabetic pregnancies as an index of vascular damage linked to oxidative stress. RESEARCH DESIGN AND METHODS: Villous tissue was collected and flash frozen after delivery from 10 class C and D IDDM patients (37.9+/-3.2 weeks) and 10 normotensive pregnant individuals (37.5+/-3.8 weeks). Serial sections of tissue were immunostained with specific antibodies to NT, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and manganese superoxide dismutase (MnSOD). Sections were scored for intensity of immunostaining (0-3) by three observers blinded to the identity of tissue. RESULTS: All tissues demonstrated immunostaining for eNOS in both syncytiotrophoblast and stem villous vascular endothelium with no apparent differences between groups. Immunostaining for iNOS was seen in the villous stroma, but again was not different between the two groups. Significantly more intense NT staining was apparent in vascular endothelium and villous stroma (both P < 0.02) of diabetic placentas. The endothelium of large villous vessels of diabetic tissues also showed more intense immunostaining for MnSOD (P < 0.01). CONCLUSIONS: In these diabetic pregnancies, we were unable to show increased eNOS, unlike previous findings in preeclamptic pregnancies. The presence of NT may indicate vascular damage in the diabetic placenta due to peroxynitrite action formed from increased synthesis/interaction of nitric oxide and superoxide. The apparently paradoxical increase in MnSOD expression may be an adaptive response to increased superoxide generation.

Nitrotyrosine residues in placenta. Evidence of peroxynitrite formation and action.

The interaction of nitric oxide and superoxide produces peroxynitrite anion, a strong, long-lived oxidant with pronounced deleterious effects that may cause vascular damage. The formation and action of peroxynitrite can be detected by immunohistochemical localization of nitrotyrosine residues. We compared the presence and localization of nitrotyrosine and of the endothelial isoform of nitric oxide synthase in placental villous tissue from normotensive pregnancies (n = 5) with pregnancies complicated by preeclampsia (n = 5), intrauterine growth restriction (n = 5), and preeclampsia plus intrauterine growth restriction (n = 4), conditions characterized by increases in fetoplacental vascular resistance, fetal platelet consumption, and fetal morbidity and mortality. In all tissues, absent or faint nitrotyrosine immunostaining but prominent nitric oxide synthase immunostaining were found in syncytiotrophoblast. In tissues from normotensive pregnancies, faint nitrotyrosine immunostaining was found in vascular endothelium, and nitric oxide synthase was present in stem villous endothelium but not in the terminal villous capillary endothelium. In contrast, in preeclampsia and/or intrauterine growth restriction, moderate to intense nitrotyrosine immunostaining was seen in villous vascular endothelium, and immunostaining was also seen in surrounding vascular smooth muscle and villous stroma. The intensity of nitrotyrosine immunostaining in preeclampsia (with or without intrauterine growth restriction) was significantly greater than that of controls. Intense nitric oxide synthase staining was seen in endothelium of stem villous vessels and the small muscular arteries of the terminal villous region in these tissues and may be an adaptive response to the increased resistance. The presence of nitrotyrosine residues, particularly in the endothelium, may indicate the formation and action of peroxynitrite, resulting in vascular damage that contributes to the increased placental vascular resistance.

The differential expression of myometrial connexin-43, cyclooxygenase-1 and -2, and Gs alpha proteins in the upper and lower segments of the human uterus during pregnancy and labor.

There is evidence from many studies indicating that a number of specific quiescent and contractile associated proteins are temporally regulated in the myometrium during pregnancy. In this present investigation we provide data that strongly suggest that myometrial connexin-43, cyclooxygenase-1 and -2 (COX-1 and -2), and Gs alpha proteins are also spatially expressed within the human uterus during pregnancy and labor. Using paired lower and upper segment myometrial samples taken from individual women at term and during spontaneous labor, we have measured the expression of these proteins by immunoblotting with specific antibodies. We report that the myometrial gap junction connexin-43 protein is expressed at much greater levels in the upper uterine compared to the lower uterine segment and that this difference is even more pronounced during the course of labor. Conversely, myometrial COX-1 and -2 proteins appear to be expressed at much greater levels in the lower compared to the upper uterine segment. Moreover, the level of expression of both proteins is unaffected by the onset of parturition. In contrast, myometrial Gs alpha protein appears to be uniformly expressed in both lower and upper segments and is similarly down-regulated during parturition, as previously reported. The differential expression of COX-1 and -2 and connexin-43 in the uterus may allow cervical ripening before and dilatation during labor and facilitate effective propagation of contractions from fundus to cervix, which may be further facilitated by the down-regulation of Gs alpha at the onset of parturition.

Effects of dexamethasone on G protein levels and adenylyl cyclase activity in rat vascular smooth muscle cells.

Dexamethasone administration in vitro has been shown to increase adenylyl cyclase activity in vascular smooth muscle cells (VSMC) from renal arteries and in non-vascular cell lines. To investigate whether G proteins are involved in this response, cultured VSMC from mesenteric arteries of Sprague-Dawley rats were incubated in the presence and absence of 10 nM dexamethasone for 24 and 48 h. Basal and stimulated adenylyl cyclase activities were increased by approximately 50% after treatment with dexamethasone. The changes were neither specifically associated with ligands which stimulate adenylyl cyclase catalytic unit via Gs (isoproterenol and prostaglandin E1) nor with guanylylimidodiphosphate (0.1 nM), which inhibits the catalytic unit via Gi. This suggests that dexamethasone enhances adenylyl cyclase activity through changes at the level of the catalytic unit, rather than through the G proteins which modulate its activity. No differences were seen in immunoblotting studies of the levels of Gi alpha 2, Gs alpha, Gi alpha 3 and beta subunits. Similarly, dexamethasone had no effect on the expression of mRNA for Gi alpha 2 and Gs alpha. The results indicate that glucocorticoid-induced increases of adenylyl cyclase activity are due to changes at the level of the adenylyl cyclase catalytic unit rather than alteration of the levels or turnover of Gs alpha, Gi alpha 2, Gi alpha 3 and beta subunits in the membranes of VSMC.

Rat atrial natriuretic peptide vascular receptor: effect of alterations in sodium balance and of DOC hypertension.

The effect of changes in dietary sodium intake and of DOC hypertension on plasma atrial natriuretic peptide (PANP), and affinity (Kd) and number (Bmax) of vascular atrial natriuretic peptide binding sites was studied in the rat. There was no difference in PANP between rats on a high or low sodium intake [33.2 +/- 13.9 versus 30.7 +/- 17.3 (s.d.) fmol/ml], Kd [21.1 +/- 2.7 versus 19.7 +/- 4.5 (s.d.) pmol/l] or Bmax [14.8 +/- 1.6 versus 12.6 +/- 1.8 (s.d.) fmol/mg], respectively. In DOC hypertensive rats, PANP was increased compared with control animals [66.1 +/- 32.4 versus 26.4 +/- 9.9 (s.d.) fmol/ml, P less than 0.05] and there was apparent receptor down-regulation [Bmax 7.7 +/- 1.6 versus 19.7 +/- 3.5 (s.d.) fmol/mg, P less than 0.05] with no change in affinity [Kd 15.6 +/- 3.9 versus 18.3 +/- 3.2 (s.d.) pmol/l]. Down-regulation was confirmed when the membrane-bound enzyme 5'-nucleotidase, rather than protein, was used as an index of receptor number. These results suggest that in the rat, atrial natriuretic peptide (ANP) may be important in regulating cardiovascular homeostasis only following non-physiological alterations in sodium and volume status.

Angiotensin II increases proto-oncogene expression and phosphoinositide turnover in vascular smooth muscle cells via the angiotensin II AT1 receptor.

OBJECTIVES: The aim of this study was to determine which angiotensin II receptor (AT receptor) mediates proto-oncogene expression and phosphoinositide metabolism in vascular smooth muscle cells in vitro. DESIGN: The AT receptor antagonists DuP753 (losartan), an AT1 antagonist, and PD 123319, an AT2 antagonist, were used to characterize AT receptors on cultured vascular smooth muscle cells derived from the rat mesenteric artery and to identify which receptor subtype mediates the angiotensin II-induced increase in proto-oncogene expression and phosphoinositide metabolism. METHODS: Rat mesenteric artery vascular smooth muscle cells were grown using standard cell culture methods. Proto-oncogene induction was measured using Northern blotting. Phosphoinositide breakdown was assessed by measuring [3H]-inositol phosphates released from prelabelled cells. RESULTS: Receptor-binding studies revealed that the AT1 receptor predominated on vascular smooth muscle cells. Incubation of quiescent cells with 0.1 mumol/l angiotensin II resulted in a 65% increase in total [3H]-inositol phosphates released compared with unstimulated cells and in a rapid accumulation of c-fos messenger RNA (mRNA). Pre-incubation of the cells with 10(-5) mol/l PD 123319 had no effect on either total inositol phosphates release or c-fos mRNA induction. Both responses, however, were totally abolished by pre-incubation of the cells with 10(-5) mol/l losartan or saralasin. CONCLUSIONS: Angiotensin II acts through the AT1 receptor to increase c-fos expression and phosphoinositide turnover in vascular smooth muscle cells. These mechanisms may be important in angiotensin II-induced smooth muscle hypertrophy.

Mechanical stretch increases proto-oncogene expression and phosphoinositide turnover in vascular smooth muscle cells.

OBJECTIVE: To determine whether changes in haemodynamic load, simulated in vitro by mechanically stretching cultured vascular smooth muscle cells, could be transduced into biochemical signals similar to those produced by growth factors. DESIGN: A system was developed which was capable of stretching cultured vascular smooth muscle cells from 0 to 20%. The effect of stretching quiescent vascular smooth muscle cells on both c-fos messenger RNA (mRNA) expression and release of total inositol phosphates was determined over a time interval of 0-360 min. METHODS: Rat mesenteric artery vascular smooth muscle cells were grown using standard cell culture methods. Induction of the proto-oncogene, c-fos, was determined by Northern blotting. Phosphoinositide breakdown was assessed by measuring [3H]-inositol phosphates released from prelabelled cells. RESULTS: A 20% fixed stretch resulted in a rapid induction of c-fos mRNA which reached maximal levels by 15 min. The amount of c-fos mRNA detected was dependent on the degree of stretch, with maximum induction obtained for 15 and 20% stretch. The effects of mechanical stretch were also assessed on phosphoinositide turnover by measuring [3H]-inositol phosphates released from prelabelled cells. A 20% fixed stretch of vascular smooth muscle cells for 20 min resulted in a 3.2-fold increase in total [3H]-inositol phosphates released compared with unstretched cells. CONCLUSIONS: Our results show that mechanical stretch increases proto-oncogene expression and phosphoinositide turnover in vascular smooth muscle cells in vitro. These observations suggest that mechanical stretch and growth factors share common signal transduction pathways which may be important in the development of vascular hypertrophy.

Differential localization of superoxide dismutase isoforms in placental villous tissue of normotensive, pre-eclamptic, and intrauterine growth-restricted pregnancies.

Several isoforms of superoxide dismutase (SOD), including copper/zinc (cytosolic) and manganese (mitochondrial), exist. In the human placenta, SOD may prevent excessive superoxide accumulation and any potential deleterious oxidative effects. In pre-eclampsia, increased levels of lipid peroxide and decreased SOD activity have been described in the placenta. Oxidative stress such as occurs in pre-eclampsia can alter expression of SOD isoforms. The objective of this study was to localize the copper/zinc and manganese SOD isoforms in the placenta using immunohistochemistry and to compare localization and intensity of immunostaining in tissues from normotensive pregnancies with those from pregnancies complicated by pre-eclampsia and/or intrauterine growth restriction (IUGR). Western blotting with specific antibodies recognized a 17-kD copper/zinc and a 23-kD manganese SOD subunit in placental homogenates. Intense immunostaining for the manganese SOD isoform was seen in villous vascular endothelium, but only faint staining was found in the syncytiotrophoblast or villous stroma. In serial sections, intense immunostaining for copper/zinc SOD was seen in certain cells of the villous stroma but only faint immunostaining in syncytiotrophoblast and vascular endothelium. No apparent differences in localization or intensity of immunostaining for either isoform were seen between tissues of normotensive or pre-eclamptic pregnancies, with or without IUGR. The different cellular localizations of the SOD isoforms suggest that they fulfill different functional roles within the placenta.

Specific binding of atrial natriuretic peptide increases cyclic GMP levels in human astrocytoma cells.

Specific high-affinity binding sites (dissociation constant 100 pmol/l) for atrial natriuretic peptide (ANP) have been identified in the clone D384 derived from the human astrocytoma cell line G-CCM. Unrelated peptides such as angiotensin II, vasopressin and bradykinin did not compete for these sites. Of the atrial natriuretic peptides studied, both the human and rat ANP competed equally, while peptides with either C- or N-terminal residue missing or with no internal -S-S-bond either competed less effectively or did not compete at all. Human ANP stimulated the cells to increase their intracellular level of cyclic GMP in a time- and dose-dependent manner with maximum stimulation being approached but not reached at concentrations of 1 mumol/l. These results support both the notion that ANP has an important functional role within the brain and the concept of neurotransmitter/neuromodulator communication between neurones and glia.