Showing papers by "Guy's and St Thomas' NHS Foundation Trust published in 1997"

Spectrum of clinical features associated with interstitial chromosome 22q11 deletions: a European collaborative study.

Abstract: We present clinical data on 558 patients with deletions within the DiGeorge syndrome critical region of chromosome 22q11. Twenty-eight percent of the cases where parents had been tested had inherited deletions, with a marked excess of maternally inherited deletions (maternal 61, paternal 18). Eight percent of the patients had died, over half of these within a month of birth and the majority within 6 months. All but one of the deaths were the result of congenital heart disease. Clinically significant immunological problems were very uncommon. Nine percent of patients had cleft palate and 32% had velopharyngeal insufficiency, 60% of patients were hypocalcaemic, 75% of patients had cardiac problems, and 36% of patients who had abdominal ultrasound had a renal abnormality. Sixty-two percent of surviving patients were developmentally normal or had only mild learning problems. The majority of patients were constitutionally small, with 36% of patients below the 3rd centile for either height or weight parameters.

Automatic correction of motion artifacts in magnetic resonance images using an entropy focus criterion

Abstract: Presents the use of an entropy focus criterion to enable automatic focusing of motion corrupted magnetic resonance images. The authors demonstrate the principle using illustrative examples from cooperative volunteers. Their technique can determine unknown patient motion or use knowledge of motion from other measures as a starting estimate. The motion estimate is used to compensate the acquired data and is iteratively refined using the image entropy. Entropy focuses the whole image principally by favoring the removal of motion induced ghosts and blurring from otherwise dark regions of the image. Using only the image data, and no special hardware or pulse sequences, the authors demonstrate correction for arbitrary rigid-body translational motion in the imaging plane and for a single rotation. Extension to three-dimensional (3-D) and more general motion should be possible. The algorithm is able to determine volunteer motion well. The mean absolute deviation between algorithm and navigator-echo-determined motion is comparable to the displacement step size used in the algorithm. Local deviations from the recorded motion or navigator-determined motion are explained and the authors indicate how enhanced focus criteria may be derived. In all cases they were able to compensate images for patient motion, reducing blurring and ghosting.

Handbook of Obstetric Medicine

Abstract: SECTION A: SYSTEMS Hypertension and pre-eclampsia Heart Disease Thromboembolic disease Respiratory disease Diabetes Thyroid and parathyroid disease Pituitary and adrenal disease Connective tissue disease Neurological problems Renal disease Liver disease Gastrointestinal disease Skin disease Haematological problems Human immunodeficiency virus (HIV) and other infectious diseases Appendix 1. Drugs to avoid in pregnancy Appendix 2. Normal laboratory values in pregnancy / non-pregnancy SECTION B: DIFFERENTIAL DIAGNOSES OF MEDICAL PROBLEMS IN PREGNANCY Breathlessness Palpitations Chest pain Heart murmur Hypertension Abnormal thyroid function tests Headache Convulsions Dizziness Collapse Numbness Proteinuria Abnormal renal function Pruritus Jaundice / abnormal liver function Vomiting Abdominal pain Index & Bibliographies

Expression and activation of SH2/PTB-containing ShcA adaptor protein reflects the pattern of neurogenesis in the mammalian brain

Abstract: The adult mammalian brain comprises many functionally distinct neuronal types, which are generated during development as a result of a coordinated signaling cascade that drives neuroblasts from proliferation into differentiation. We investigated whether and how ShcA adaptor proteins, which are known to function as initiators of the Ras signaling cascade in various nonneuronal systems where they have been considered to be expressed ubiquitously, are involved in the proliferative and differentiative phases of the developing brain. We found that in the forebrain expression and activation of ShcA proteins were strictly regulated during embryonic development, both temporally and spatially. The mRNAs encoded by the ShcA gene were expressed exclusively within an area to which active proliferation of immature neuroblasts was confined, the ventricular zone. In postnatal and adult brain, ShcA mRNAs and proteins were present only faintly. In the adult olfactory epithelium, in which neuronal cell renewal occurs throughout life, ShcA remained strongly expressed. These phenomena were peculiar to ShcA, since Grb2 adaptor protein remained expressed at constant level throughout development. The embryonically expressed ShcA proteins were functionally active, since p52ShcA became phosphorylated on tyrosine and associated with Grb2 following intraventricular injection of epidermal growth factor in the embryonic brain. Our data indicate that, through an orderly pattern of expression, ShcA gene products may play a role in the control of the switch between proliferation and differentiation of brain neuroblasts.

Abnormal sulfate metabolism in vitamin D-deficient rats.

Abstract: To explore the possibility that vitamin D status regulates sulfate homeostasis, plasma sulfate levels, renal sulfate excretion, and the expression of the renal Na-SO4 cotransporter were evaluated in vitamin D-deficient (D-D-) rats and in D-D- rats rendered normocalcemic by either vitamin D or calcium/lactose supplementation. D-D- rats had significantly lower plasma sulfate levels than control animals (0.93+/-0.01 and 1.15+/-0.05 mM, respectively, P < 0.05), and fractional sulfate renal excretion was approximately threefold higher comparing D-D- and control rats. A decrease in renal cortical brush border membrane Na-SO4 cotransport activity, associated with a parallel decrease in both renal Na-SO4 cotransport protein and mRNA content (78+/-3 and 73+/-3% decreases, respectively, compared with control values), was also observed in D-D- rats. Vitamin D supplementation resulted in a return to normal of plasma sulfate, fractional sulfate excretion, and both renal Na-SO4 cotransport mRNA and protein. In contrast, renal sulfate excretion and renal Na-SO4 cotransport activity, protein abundance, and mRNA remained decreased in vitamin D-depleted rats fed a diet supplemented with lactose and calcium, despite that these rats were normocalcemic, and had significantly lower levels of parathyroid hormone and 25(OH)- and 1,25(OH)2-vitamin D levels than the vitamin D-supplemented groups. These results demonstrate that vitamin D modulates renal Na-SO4 sulfate cotransport and sulfate homeostasis. The ability of vitamin D status to regulate Na-SO4 cotransport appears to be a direct effect, and is not mediated by the effects of vitamin D on plasma calcium or parathyroid hormone levels. Because sulfate is required for synthesis of essential matrix components, abnormal sulfate metabolism in vitamin D-deficient animals may contribute to producing some of the abnormalities observed in rickets and osteomalacia.

Endothelial cells as a target for antiphospholipid antibodies: role of anti-beta 2 glycoprotein I antibodies.

Abstract: PROBLEM: To investigate the role of the plasma cofactor for antiphospholipid antibodies in antibody binding to endothelial cells. METHOD OF STUDY: a) Evaluation of endothelial cell binding of polyclonal and monoclonal anti-β2 glycoprotein I antibodies; and b) study of the effects of antibody binding: adhesion molecule expression, leukocyte adhesion, and interleukin-1β secretion. RESULTS: Anti-β2 glycoprotein I antibodies bind endothelial cell monolayers in vitro by reacting with the cofactor adhered to the cell membranes. Antibody binding induces an up-regulation of adhesion molecules, favours leukocyte adherence, and increases interleukin-1β secretion. InterIeukin-1β plays an active role to mediate adhesion molecule expression through an autocrine loop, as shown by the inhibitory effect of interleukin I receptor antagonist. CONCLUSIONS: Antiphospholipid antibodies do react with endothelium through the cofactor adhered to their cell membranes and induces a pro-adhesive cell phenotype.

Scanning electron microscopy and energy dispersive analysis of machined denture base surfaces.

Abstract: To relate the characteristics of rotary instruments to the surfaces they produce, acrylic resin, Molloplast B, and Novus were investigated with energy dispersive analysis and scanning electron microscopy (secondary and backscatter images) before and after machining. The chemical composition of cutting instruments, material surfaces, and residues was identified. Machined debris embedded in Molloplast B after machining with the Molloplast stone was found to contain a mean lead content of 45%. High concentrations of barium sulphate were discovered on the arbor band-machined surface of Novus. These differences were related to clinically appropriate instrumentation, and, therefore, biocompatability studies that intimately relate to the in vivo situation should be considered for new materials.