Pregnancies in women with Turner syndrome: a retrospective multicentre UK study.

OBJECTIVE: To determine the characteristics and outcomes of pregnancy in women with Turner syndrome. DESIGN: Retrospective 20-year cohort study (2000-20). SETTING: Sixteen tertiary referral maternity units in the UK. POPULATION OR SAMPLE: A total of 81 women with Turner syndrome who became pregnant. METHODS: Retrospective chart analysis. MAIN OUTCOME MEASURES: Mode of conception, pregnancy outcomes. RESULTS: We obtained data on 127 pregnancies in 81 women with a Turner phenotype. All non-spontaneous pregnancies (54/127; 42.5%) were by egg donation. Only 9/31 (29%) pregnancies in women with karyotype 45,X were spontaneous, compared with 53/66 (80.3%) pregnancies in women with mosaic karyotype 45,X/46,XX (P < 0.0001). Women with mosaic karyotype 45,X/46,XX were younger at first pregnancy by 5.5-8.5 years compared with other Turner syndrome karyotype groups (P < 0.001), and more likely to have a spontaneous menarche (75.8% versus 50% or less, P = 0.008). There were 17 miscarriages, three terminations of pregnancy, two stillbirths and 105 live births. Two women had aortic dissection (2.5%); both were 45,X karyotype with bicuspid aortic valves and ovum donation pregnancies, one died. Another woman had an aortic root replacement within 6 months of delivery. Ten of 106 (9.4%) births with gestational age data were preterm and 22/96 (22.9%) singleton infants with birthweight/gestational age data weighed less than the tenth centile. The caesarean section rate was 72/107 (67.3%). In only 73/127 (57.4%) pregnancies was there documentation of cardiovascular imaging within the 24 months before conceiving. CONCLUSIONS: Pregnancy in women with Turner syndrome is associated with major maternal cardiovascular risks; these women deserve thorough cardiovascular assessment and counselling before assisted or spontaneous pregnancy managed by a specialist team. TWEETABLE ABSTRACT: Pregnancy in women with Turner syndrome is associated with an increased risk of aortic dissection.

Inhaled corticosteroids and HPA axis suppression: how important is it and how should it be managed?

Inhaled corticosteroids (ICS) are established as a cornerstone of management for patients with bronchoconstrictive lung disease. However, systemic absorption may lead to suppression of the hypothalamic-pituitary-adrenal (HPA) axis in a significant minority of patients. This is more likely in 'higher risk' patients exposed to high cumulative ICS doses, and in those treated with frequent oral corticosteroids or drugs which inhibit cytochrome p450 3A4. Hypothalamic-pituitary-adrenal axis suppression is frequently unrecognized, such that some patients, notably children, only come to light when an adrenal crisis is precipitated by physical stress. To minimize this risk, 'higher risk' patients and those with previously identified suppressed cortisol responses to Synacthen testing should undergo an education programme to inform them about sick day rules. A review of ICS therapy should also be undertaken to ensure that the dose administered is the minimum required to control symptoms.

Young women with polycystic ovary syndrome have raised levels of circulating annexin V-positive platelet microparticles.

STUDY QUESTION: Are circulating microparticles (MPs) altered in young women with polycystic ovary syndrome (PCOS)? SUMMARY ANSWER: Women with PCOS have elevated concentrations of circulating platelet-derived MPs, which exhibit increased annexin V binding and altered microRNA (miR) profiles compared with healthy volunteers. WHAT IS KNOWN ALREADY: Some studies have shown that cardiovascular risk is increased in young women with PCOS but the mechanisms by which this occurs are uncertain. Circulating MPs are elevated in patients with cardiovascular disease but the characteristics of MPs in patients with PCOS are unclear. STUDY DESIGN, SIZE, DURATION: Case-control study comprising 17 women with PCOS (mean ± SD; age 31 ± 7 years, BMI 29 ± 6 kg/m(2)) and 18 healthy volunteers (age 31 ± 6 years, BMI 30 ± 6 kg/m(2)). PARTICIPANTS/MATERIALS, SETTING, METHODS: The study was conducted in a University hospital. Nanoparticle tracking analysis (NTA) and flow cytometry (CD41 platelet, CD11b monocyte, CD144 endothelial) were used to determine MP size, concentration, cellular origin and annexin V positivity (reflecting phosphatidylserine exposure). Fatty acid analysis was performed by gas chromatography and MP miR expression profiles were compared by microarray. MAIN RESULTS AND THE ROLE OF CHANCE: PCOS subjects showed increased MP concentrations compared with healthy volunteers (mean ± SD; 11.5 ± 5 × 10(12)/ml versus 10.0 ± 4 × 10(12)/ml, respectively; P = 0.03), which correlated with the homeostasis model of insulin resistance (r = 0.53, P = 0.03). This difference was predominantly seen in MPs whose size was in the small exosomal range (<150 nm in diameter, P< 0.05). PCOS patients showed a greater percentage of annexin V(+) MPs compared with healthy volunteers (84 ± 18 versus 74 ± 24%, respectively, P = 0.05) but the cellular origin of MPs, which were predominantly platelet-derived (PCOS: 99 ± 0.9%; controls: 99 ± 2.5%), did not differ. MP fatty acid concentration and composition was similar between groups but 16 miRs were differentially expressed (P < 0.05). LIMITATIONS, REASON FOR CAUTION: Patients with PCOS were classified by the Rotterdam criteria, which describes a less severe metabolic phenotype than other definitions of the syndrome. Our findings may thus not be generalizable to all patients with PCOS. MicroRNA expression analysis was only undertaken in an exploratory subset of the overall study population hence, validation of our findings in a larger cohort is mandatory. Furthermore, miR levels were unaltered for the highly expressed miRs and it is unclear whether differences in the lowly expressed miRs carries pathological relevance. WIDER IMPLICATIONS OF THE FINDINGS: This study suggests that women with PCOS have an altered MP profile but further studies are needed to confirm this, to explore the mechanisms by which these alterations develop and to establish whether therapies that improve insulin sensitivity are able to reduce circulating MP concentrations. STUDY FUNDING/COMPETING INTERESTS: The study was funded by grants from the Wales Heart Research Institute and Mrs John Nixon Scholarship. The authors have no conflicts of interest to declare.

Central arterial stiffness and diastolic dysfunction are associated with insulin resistance and abdominal obesity in young women but polycystic ovary syndrome does not confer additional risk.

STUDY QUESTION: Are arterial stiffness, carotid intima-media thickness and diastolic dysfunction increased in young women with polycystic ovary syndrome (PCOS) independently of the effects of obesity? SUMMARY ANSWER: Insulin resistance and central obesity are associated with subclinical cardiovascular dysfunction in young women, but a diagnosis of PCOS does not appear to confer additional risk at this age. WHAT IS KNOWN ALREADY: Some studies have shown that young women with PCOS may have increased measures of cardiovascular risk, including arterial stiffness, carotid intima-media thickness and myocardial dysfunction. However, it is difficult to establish how much of this risk is due to PCOS per se and how much is due to obesity and insulin resistance, which are common in PCOS and themselves associated with greater vascular risk. STUDY DESIGN, SIZE, DURATION: This cross-sectional study comprised 84 women with PCOS and 95 healthy volunteers, aged 16-45 years. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study was conducted in a university hospital. Subjects underwent a comprehensive assessment of body composition (including computed tomography (CT) assessment of visceral fat; VF), measurements of arterial stiffness (aortic pulse wave velocity; aPWV), common carotid intima-media thickness (ccIMT), diastolic function (longitudinal tissue velocity; e':a') and endocrinological measures. A sample size of 80 in each group gave 80% power for detecting a difference of 0.45 m/s in aPWV or a difference of 0.25 in e':a'. MAIN RESULTS AND THE ROLE OF CHANCE: After adjustment for age and body mass index (BMI), PCOS subjects had a greater insulin response (insulin area under the curve-IAUC) following glucose challenge (adjusted difference [AD] 35 900 pmol min/l, P < 0.001) and higher testosterone (AD 0.57 nmol/l, P < 0.001) and high molecular weight adiponectin than controls (AD 3.01 µg/ml, P = 0.02), but no significant differences in aPWV (AD -0.13 m/s, P = 0.33), ccIMT (AD -0.01 mm, P = 0.13), or e':a' (AD -0.01, P = 0.86) were observed. After adjustment for age, height and central pulse pressure, e':a' and aPWV were associated with logVF and IAUC. ccIMT was not related to logVF. The relationships between e':a' or aPWV and insulin resistance were only partly attenuated by adjusting for logVF. There was no significant relationship between aPWV or e':a' and either testosterone or adiponectin. LIMITATIONS, REASONS FOR CAUTION: The study recruited young women meeting the Rotterdam criteria for PCOS diagnosis; hence our findings may not be generalizable to older patients or those meeting other definitions of the syndrome. Biochemical hyperandrogenism was based solely on measurement of total testosterone. Cases and controls were not matched in advance for age and BMI, although the influence of these variables on the cardiovascular outcome measures was adjusted for. WIDER IMPLICATIONS OF THE FINDINGS: This study shows that central arterial stiffness and diastolic dysfunction are not increased in young women with PCOS, whereas they are associated with both insulin resistance and central obesity. Obesity thus represents the greatest modifiable risk factor for cardiovascular disease in young women with PCOS and lifestyle measures which target weight reduction are critical. STUDY FUNDING/COMPETING INTERESTS: This study received no specific grant support from any funding body. The authors have no conflicts of interest to declare.

Detailed characterisation of circulatory nitric oxide and free radical indices--is there evidence for abnormal cardiovascular homeostasis in young women with polycystic ovary syndrome?

OBJECTIVE: To assess circulating biochemical indices of endothelial function and nitro-oxidative stress in women with polycystic ovary syndrome (PCOS). DESIGN: Case-control study. POPULATION: Seventeen women with PCOS and eighteen age- and body mass index-matched healthy volunteers. METHODS: Nitric oxide (NO) metabolite levels were assessed by chemiluminescence. Electron paramagnetic resonance spectroscopy with spin trapping was used to assess oxidative stress ex vivo and in vitro. Antioxidant capacity was measured using oxygen radical absorbance. MAIN OUTCOME MEASURES: Biochemical indices of endothelial function, including NO metabolites, lipid-derived radicals and antioxidant capacity. RESULTS: Plasma NO metabolites were similar in the two groups (nitrite: 257±116 nmol/l [PCOS], 261±135 nmol/l [controls] P=0.93; nitrate: 27±7 µmol/l [PCOS], 26±6 µmol/l [controls] P=0.89). Alkoxyl free radicals (lipid-derived) were detected as the dominant species, but levels were not different between women with PCOS and controls whether measured directly ex vivo (median 7.2 [range 0.17-16.73]e6 arbitrary units [a.u.] and 7.2 [1.7-11.9]e6 a.u., respectively, P=0.57) or when stimulated in vitro to test radical generation capacity (1.23 [0.3-5.62]e7 a.u. and 1.1 [0.48-15.7]e7 a.u. respectively, P=0.71). In regression analysis, visceral fat area was independently associated with in vitro oxidative potential (ß=0.6, P=0.002). Total plasma antioxidant capacity (94±30% [PCOS], 79±24% [controls], P=0.09) and plasma hydroperoxides (7.5±4 µmol/l [PCOS], 6.7±5 µmol/l [controls], P=0.21) were not different between groups. However, lipophilic antioxidant capacity was lower in women with PCOS compared with controls (92±32 and 125±48%, respectively, P=0.02). CONCLUSIONS: Young overweight women with PCOS display a reduced lipophilic antioxidant capacity compared with healthy volunteers, but no change in circulating free radicals or nitro-oxidative stress.

Pearls & Oy-sters: AARS2 Leukodystrophy-Tremor and Tribulations.

A 35-year-old woman with a progressive, bilateral upper limb tremor, personality change, behavioral disturbance, and primary ovarian insufficiency was found to have AARS2-related leukodystrophy. She had congenital nystagmus which evolved to head titubation by age 8 years and then developed an upper limb tremor in her mid-teens. These symptoms stabilized during her 20s, but soon after this presentation at age 35 years, neurologic and behavioral disturbances progressed rapidly over a 12-month period requiring transition to an assisted living facility with care support (4 visits/day) and assistance for all activities of daily living. MRI of the brain demonstrated confluent white matter changes predominantly involving the frontal lobes consistent with a leukodystrophy. All other investigations were unremarkable. Nongenetic causes of a leukodystrophy including sexually transmitted diseases and recreational drug use were excluded. Family history was negative for similar symptoms. Gene panel testing identified compound heterozygous pathogenic AARS2 mutations. This case highlights the importance of MRI brain imaging in progressive tremor syndromes, the utility of gene panels in simultaneous testing of multiple disorders with overlapping phenotypes, and the need for awareness of comorbid endocrinological disorders in many of the genetic leukodystrophies, whose identification may aid in clinical diagnosis.

Glucocorticoid treatment regimen and health outcomes in adults with congenital adrenal hyperplasia.

BACKGROUND: Adults with congenital adrenal hyperplasia (CAH) are treated with a wide variety of glucocorticoid treatment regimens. OBJECTIVE, DESIGN AND METHODS: To test whether drug dose and timing of glucocorticoid treatment regimen impacts on health outcomes. This was a cross-sectional study of 196 adult CAH patients in whom treatment and health outcomes were measured. Glucocorticoid dose was converted to prednisolone dose equivalent (PreDEq) using three published formulae. Associations between the type of glucocorticoid regimen and PreDEq with specific health outcome variables were tested using partial correlation and principal components analysis (PCA). RESULTS: Patients on dexamethasone had lower androgens and ACTH but greater insulin resistance compared with those receiving hydrocortisone or prednisolone. Dexamethasone dose and once daily administration were associated with insulin resistance. Partial correlation analysis adjusted for age and sex showed PreDEq weakly correlated (r < 0·2) with blood pressure and androstenedione. Mutation severity was associated with increased PreDEq (F(3,141)  = 4·4, P < 0·01). In PCA, 3 PCs were identified that explained 62% of the total variance (r(2) ) in observed variables. Regression analysis (age and sex adjusted) confirmed that PC2, reflecting disease control (androstenedione, 17-hydroxypregesterone and testosterone), and PC3, reflecting blood pressure and mutations (systolic and diastolic blood pressure and mutation severity), related directly to PreDEq (r(2)  = 23%, P < 0·001). CONCLUSIONS: In adults with congenital adrenal hyperplasia, dexamethasone use was associated with lower androgens but greater insulin resistance, and increasing glucocorticoid dose associated with increased blood pressure, poor disease control and mutation severity.

Adenosine A2A and A2B receptor expression in neuroendocrine tumours: potential targets for therapy.

The clinical management of neuroendocrine tumours is complex. Such tumours are highly vascular suggesting tumour-related angiogenesis. Adenosine, released during cellular stress, damage and hypoxia, is a major regulator of angiogenesis. Herein, we describe the expression and function of adenosine receptors (A(1), A(2A), A(2B) and A(3)) in neuroendocrine tumours. Expression of adenosine receptors was investigated in archival human neuroendocrine tumour sections and in two human tumour cell lines, BON-1 (pancreatic) and KRJ-I (intestinal). Their function, with respect to growth and chromogranin A secretion was carried out in vitro. Immunocytochemical data showed that A(2A) and A(2B) receptors were strongly expressed in 15/15 and 13/18 archival tumour sections. Staining for A(1) (4/18) and A(3) (6/18) receptors was either very weak or absent. In vitro data showed that adenosine stimulated a three- to fourfold increase in cAMP levels in BON-1 and KRJ-1 cells. The non-selective adenosine receptor agonist (adenosine-5'N-ethylcarboxamide, NECA) and the A(2A)R agonist (CGS21680) stimulated cell proliferation by up to 20-40% which was attenuated by A(2B) (PSB603 and MRS1754) and A(2A) (SCH442416) receptor selective antagonists but not by the A(1) receptor antagonist (PSB36). Adenosine and NECA stimulated a twofold increase in chromogranin A secretion in BON-1 cells. Our data suggest that neuroendocrine tumours predominantly express A(2A) and A(2B) adenosine receptors; their activation leads to increased proliferation and secretion of chromogranin A. Targeting adenosine signal pathways, specifically inhibition of A(2) receptors, may thus be a useful addition to the therapeutic management of neuroendocrine tumours.

Fibroblast adhesion to RGDS shows novel features compared with fibronectin.

As previously shown by others, the fibroblast attachment and spreading activity of fibronectin is mimicked by a short peptide (RGDS or longer) from the cell binding domain. Normal rat kidney fibroblasts showed similar attachment kinetics on either peptide GRGDSC or bovine plasma fibronectin and binding to either substratum was inhibited by peptide alone. We now demonstrate, however, considerable differences in biological activity between peptide and fibronectin. In particular, cells developed novel adhesion structures on peptide-coated substrata. Interference reflection microscopy showed a predominance of small round dark grey/black patches of adherent membrane ("spots") with relatively few focal adhesions, which occurred only at the outermost cell margins in contrast to their distribution in cells spread on fibronectin. The spots were resistant to detergent extraction and stained less strongly or not at all for vinculin. Electron microscopy in vertical thin section showed that the ventral surface of the cell was characterized by "point-contacts", corresponding in size to the spot structures seen by interference reflection microscopy, and which were only occasionally associated with microfilaments. Cells also required a higher substratum loading of peptide than fibronectin to promote spreading and proceeded to spread less rapidly and to a lesser extent, developing very few and extremely fine actin cables.

Adhesion, growth, and matrix production by fibroblasts on laminin substrates.

Human embryonic skin fibroblasts have been shown to attach and spread on laminin substrates in the absence of protein synthesis and presence of fibronectin-depleted serum and anti-fibronectin antibodies. Rates of attachment and the type of spreading are virtually identical on fibronectin and laminin-coated substrates with the development of microfilament bundles and focal adhesions. Antibodies to laminin, but not fibronectin, will prevent or reverse fibroblast adhesion to laminin, whereas antibodies to fibronectin but not laminin will give similar results on fibronectin-coated substrates. These and other results indicate that fibroblasts possess distinct receptors for laminin and fibronectin which on contact with suitable substrates promote adhesion through interaction with common intermediates. This type of adhesion is compatible with subsequent growth and extracellular matrix production.

Structure and assembly of desmosome junctions: biosynthesis, processing, and transport of the major protein and glycoprotein components in cultured epithelial cells.

Extracts of metabolically labeled cultured epithelial cells have been analyzed by immunoprecipitation followed by SDS-PAGE, using antisera to the major high molecular mass proteins and glycoproteins (greater than 100 kD) from desmosomes of bovine muzzle epidermis. For nonstratifying cells (Madin-Darby canine kidney [MDCK] and Madin-Darby bovine kidney), and A431 cells that have lost the ability to stratify through transformation, and a stratifying cell type (primary human keratinocytes) apparently similar polypeptides were immunoprecipitated with our antisera. These comprised three glycoproteins (DGI, DGII, and DGIII) and one major nonglycosylated protein (DPI). DPII, which has already been characterized by others in stratifying tissues, appeared to be absent or present in greatly reduced amounts in the nonstratifying cell types. The desmosome glycoproteins were further characterized in MDCK cells. Pulse-chase studies showed all three DGs were separate translation products. The two major glycoprotein families (DGI and DGII/III) were both found to be synthesized with co-translational addition of 2-4 high mannose cores later processed into complex type chains. However, they became endo-beta-N-acetylglucosaminidase H resistant at different times (DGII/III being slower). None of the DGs were found to have O-linked oligosaccharides unlike bovine muzzle DGI. Transport to the cell surface was rapid for all glycoproteins (60-120 min) as demonstrated by the rate at which they became sensitive to trypsin in intact cells. This also indicated that they were exposed at the outer cell surface. DGII/III, but not DGI, underwent a proteolytic processing step, losing 10 kD of carbohydrate-free peptide, during transport to the cell surface suggesting a possible regulatory mechanism in desmosome assembly.

Structure and assembly of desmosome junctions: biosynthesis and turnover of the major desmosome components of Madin-Darby canine kidney cells in low calcium medium.

Neither stratifying (primary keratinocytes) nor simple (Madin-Darby canine kidney [MDCK] and Madin-Darby bovine kidney [MDBK]) epithelial cell types from desmosomes in low calcium medium (LCM; less than 0.1 mM), but they can be induced to do so by raising the calcium level to physiological concentrations (standard calcium medium [SCM], 2 mM). We have used polyclonal antisera to the major bovine epidermal desmosome components (greater than 100 kD) in a sensitive assay involving immunoprecipitation of the components from metabolically labeled MDCK cell monolayers to investigate the mechanism of calcium-induced desmosome formation. MDCK cells, whether cultured in LCM or SCM, were found to synthesize the desmosome protein, DPI and desmosome glycoproteins DGI and DGII/III with identical electrophoretic mobility, and also, where relevant, with similar carbohydrate addition/processing and proteolytic processing. The timings of these events and of transport of DGI to the cell surface were similar in low and high calcium. Although the rates of synthesis of the various desmosome components were also similar under both conditions, the glycoprotein turnover rates increased dramatically in cells cultured in LCM. The half-lives decreased by a factor of about 7 for DGI and 12 for DGII/III and, consistent with this, MDCK cells labeled for 48 h in SCM had three and six times the amount of DGI and DGII/III, respectively, as cells labeled for 48 h in LCM. The rate of turnover and the levels of DPI were changed in the same direction, but to much lesser extents. Possible mechanisms for the Ca2+-dependent control of desmosome formation are discussed in the light of this new evidence.

Relationship of heparan sulfate proteoglycans to the cytoskeleton and extracellular matrix of cultured fibroblasts.

The distribution of heparan sulfate proteoglycans (HSPG) on cultured fibroblasts was monitored using an antiserum raised against cell surface HSPG from rat liver. After seeding, HSPG was detected by immunofluorescence first on cell surfaces and later in fibrillar deposits of an extracellular matrix. Cell surface HSPG aligned with microfilament bundles of rat embryo fibroblasts seen by phase-contrast microscopy but was diffuse on transformed rat dermal fibroblasts (16C cells) which lack obvious stress fibers. Focal adhesions isolated from either cell type and monitored by interference reflection microscopy showed a concentration of HSPG labeling with respect to the rest of the membrane. Increased labeling in these areas was also seen for fibronectin (FN) by using an antiserum that detects both plasma and cell-derived FN. Double immunofluorescent staining of fully adherent rat embryo fibroblast cells showed some co-distribution of HSPG and FN, and this was confirmed by immunoelectron microscopy, which detected HSPG at localized areas of dorsal and ventral cell membranes, overlapping cell margins, and in the extracellular matrix. During cell shape changes on rounding and spreading, HSPG and FN may not co-distribute. Double labeling for actin and either HSPG or FN showed a closer correlation of actin with HSPG than with FN. The studies are consistent with HSPG being closely involved in a transmembrane cytoskeletal-matrix interaction; the possibility that HSPG coordinates the deposition of FN and other matrix components with cytoskeletal organization is discussed.

Fibronectin has a dual role in locomotion and anchorage of primary chick fibroblasts and can promote entry into the division cycle.

Fibronectin (FN), which is already known to be a natural factor for fibroblast spreading on substrata, has now been shown to be essential for two distinct types of adhesion with different biological functions in chick heart fibroblasts, namely adhesion directed toward locomotion and toward stationary anchorage for growth. Manipulation of culture conditions and the use of antisera of differing specificities has demonstrated that both exogenous and cell-derived FN are important in each process. The organization of the fibronectin-containing matrix differs between the two states. Immunoelectron microscopy with a colloidal gold marker reveals the presence of small membrane-associated plaques of fibronectin in motile cells with associated submembranous specialization. A fibrillar matrix containing fibronectin is dominant in nonmotile, growing fibroblasts. The development of focal adhesions for stationary anchorage can be dramatically enhanced by addition of cell-derived FN at an appropriate stage, and this promotes entry into the growth cycle. New macromolecular synthesis in addition to FN is necessary for focal adhesion development but not for locomotion.

Hyaluronic acid: a novel, double helical molecule.

Films prepared from a deformable gel (or putty) of hyaluronic acid show high crystallinity and orientation in their x-ray diffraction patterns. We have derived a probable structure for the molecules in these films. This is a double helix in which two identical, left-handed strands are antiparallel to one another. Each strand has four disaccharide residues per pitch length. Although the putty is prepared at pH 2.5, at which dilute solutions of hyaluronic have exaggerated rheological properties, the double helical form can also exist at physiological pH and therefore may be a biologically important form.

Can abdominal bioelectrical impedance refine the determination of visceral fat from waist circumference?

Ryo et al (2005 Diabetes Care 28 451-3) reported a new method for measuring the visceral fat area (VFA) by combining abdominal bioelectrical impedance analysis (BIA) with measurement of waist circumference (WC), but very few methodological details were provided. Furthermore, the study did not test the use of WC alone as an indicator of VFA even though others had previously reported a strong correlation. We sought to determine the optimal measurement technique and analysis for measuring VFA by abdominal BIA and WC. 18 volunteers (age 23-64 years) underwent measurement of WC, abdominal impedance (Bodystat 500 four-electrode system) and a single cross-sectional CT scan at the umbilicus. VFA derived using WC(3) and measurements of abdominal impedance from electrode pairs sited at the flank predicted the value of VFA measured by CT with correlation r = 0.904 (p < 0.0001); the optimizing power of WC was 3.3 (r = 0.905). However, the use of WC(1.9) alone, without involving BIA at all, provided a similar correlation (r = 0.923). Our small preliminary study shows that abdominal BIA is potentially a practicable non-invasive technique for measurement of VFA but casts doubt on whether it adds any value to the use of WC alone. Larger studies are now required to test this finding.

Pheochromocytoma in Pregnancy: When is Operative Intervention Indicated?

Pheochromocytoma is rare in pregnancy, with an estimated incidence of 0.007%. Diagnosis is difficult owing to the variety of presentations and nonspecific symptoms. Nevertheless, unsuspected disease accounts for a significant proportion of morbidity and mortality. Currently, there appears to be no consensus on management with regard to the need for and timing of medical vs. surgical management. In this case report, we describe two patients who underwent different modes of treatment based on careful consideration of disease-related and nondisease-related factors. We emphasise that good outcomes can be achieved through individualized management within the context of a multidisciplinary team, involving close collaboration among physicians, surgeons, obstetricians, and anesthetists. We also illustrate the importance of genetic testing in all patients with pheochromocytoma in pregnancy, especially with the emergence of new predisposing genes (succinate dehydrogenase B and D) and the recognition that germline mutations in these and more established genes (VHL and RET) account for over a quarter of all apparently sporadic cases.

Analysis of the proteins, glycoproteins and glycosaminoglycans of fibroblast adhesions to substratum.

The focal adhesion preparations which remain attached to a glass substratum when fibroblast bodies are removed by a gentle stream of buffer have been analysed by gel electrophoresis coupled with other selective methods of analysis. The results are consistent with the presence of three classes of macromolecular components. (i) Muscle and associated proteins amongst which actin was abundant with significant amounts of tropomyosin, some myosin and traces of alpha-actinin. Some vimentin was present but no vinculin. We detected a major new protein component, as yet unidentified, with a molecular weight in the region of 50000-55000 which is not desmin or tubulin and could have an important function at the focal adhesion. (ii) Glycoproteins which are a specialised subset of those in the whole plasma membrane and included a family which bind ricin and therefore contain beta-galactose end groups, together with a series having carbohydrate chains which bound neither ricin nor concanavalin A. The relative proportion of ricin-binding glycoproteins compared to concanavalin A-binding glycoproteins was higher than in whole plasma membranes. (iii) Glycosaminoglycans, with hyaluronate identified as the major component by column chromatography and its susceptibility to Streptomyces hyaluronidase.

Vacuum ultraviolet circular dichroism of fibronectin. Dominant tyrosine effects.

The spectroscopic authenticity of a very intense negative band at about 183 nm reported previously from conventional circular dichroism (c.d.) studies of bovine plasma fibronectin has now been confirmed by vacuum ultraviolet c.d. measurements on two prototype spectrometers, one using a conventional light source and the other using synchrotron radiation. Closely similar spectra were obtained from both instruments, and from both solid films and solutions. The spectra show no obvious parentage in the known c.d. of the peptide backbone, but have marked similarities to the c.d. of N-acetyltyrosineamide, both in the strong band at 183 nm and in a characteristic positive band at 230 nm, It is concluded that the c.d. of fibronectin is dominated by contributions from tyrosine side-chains and that, as suggested previously, these may provide a sensitive probe for molecular organization and interactions.

Mechanism and dynamics of conformational ordering in xanthan polysaccharide.

The thermally induced order-disorder transition of xanthan (extracellular bacterial polysaccharide from Xanthomonas campestris) has been investigated by optical rotation, differential scanning calorimetry, stopped-flow reaction kinetics and low-angle laser light scattering, and the results have been analysed in terms of Zimm -Bragg helix-coil transition theory. The reciprocal of the transition midpoint temperature (Tm) varies linearly with the logarithm of cation (K+) the salt dependence of Tm, is in agreement with Manning polyelectrolyte theory the ordered structure. The associated increase in cation binding, calculated from the salt dependence of tm, is in agreement with the Manning polyelectrolyte theory for one of the candidate structures from X-ray diffraction, a 5(1) single helix stabilized by packing of side-chains along the polymer backbone, but not for the alternative double-helix structure that has also been proposed. At each salt concentration, the two fundamental parameters of the Zimm -Bragg theory, s and sigma, were calculated. The equilibrium constant for growth of the ordered structure (s) is derived directly from calorimetric measurement of transition enthalpy (delta Hcal ), and sigma, which quantifies the relative instability of the helix nucleus, is derived from the ratio of delta Hcal to the apparent transition enthalpy (delta Happ ) obtained by van't Hoff analysis of the optical rotation data. The temperature course of conformational ordering calculated theoretically is in good quantitative agreement with experimental results from both optical rotation and scanning calorimetry. The calculated average length of stable, ordered chain-sequences increases with decreasing temperature, but equals or exceeds the total chain length from light scattering only at temperatures more than approximately equal to 70 K below Tm, suggesting that ordered and disordered regions may co-exist within the same xanthan molecule. Consistent with this interpretation, the observed rate of conformational ordering increases sharply under conditions where the starting solution for dynamic measurements is partially ordered, suggesting that ordered sequences within each chain may act as helix nuclei for adjacent disordered regions, so that helix growth, rather than the slower nucleation process, becomes rate limiting.