Biomedical subjects
Publications and source records attributed to N Barnes.
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Most neonatal X-rays are seen initially by a paediatrician without formal training in interpretation of chest X-rays. This article aims to help improve the information obtained from these X-rays which are often complex. Many factors affect accurate interpretation of the neonatal chest X-ray, including good quality radiographs, appropriate viewing conditions and thorough education.
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Angiotensin II (ANG II) is a potent vasoconstrictor and growth promoter. Quantitative receptor autoradiography using the nonselective radioligand [125I]ANG II and subtype-selective competing compounds demonstrated the presence of both ANG II receptor (AT)1 and AT2 receptor recognition sites. In addition, a relatively small population of apparently non-AT1/non-AT2 sites was identified that may represent a novel high affinity ANG II recognition site in human placenta. Using placental membrane preparations, the AT2 receptor antagonist PD123177 failed to compete for [3H]ANG II binding at relevant concentrations, whereas the AT1 receptor antagonist losartan competed in a monophasic manner for all the specific binding, suggesting that the non-AT1/non-AT2 recognition site identified using autoradiography may be a cytosolic binding site. AT1 receptor binding was significantly reduced (P < 0. 02) in intraeuterine growth restriction (IUGR) pregnancies. Western blot analysis confirmed this showing a reduction in AT1 receptor protein. In situ hybridization and immunocytochemistry revealed that AT1 receptor mRNA and protein were localized throughout pregnancy in the cytotrophoblast, syncytiotrophoblast, and extravillous trophoblast, as well as in or around the blood vessels of placental villi. The intensity of the hybridization signal for AT1 receptor mRNA over the syncytium was reduced in IUGR. ANG II evoked a rapid and concentration-dependent release of NO in first trimester cytotrophoblast-like cells that was abolished by the inclusion of the competitive NOS inhibitor NG-monomethyl-L-arginine. Neither losartan nor PD123177 alone significantly inhibited ANG II-evoked NO release, and when cells were stimulated with ANG II in the presence of losartan (10 microM) and PD123177 (10 microM) in combination, NO release was significantly inhibited (P < 0.05). These observations also suggest, for the first time, the existence of a cross-talk between AT1 or AT2 receptors in trophoblast and that the reduction in placental AT1 receptors in IUGR may, in part, account for poor placental function in this disorder.
Mouse IgG3 appears early in immune responses independently of T cell help and, as such, is an early effector molecule of the immune system. Yet, a specific IgG3 cellular receptor remains undefined. In transfection experiments, mouse Fc gammaRI was clearly able to bind immune complexes of IgG3, whereas mouse Fc gammaRII could not. Furthermore, macrophages from mice expressing Fc gammaRII and Fc gammaRIII but lacking Fc gammaRI were unable to phagocytose IgG3 immune complexes, thus identifying mouse Fc gammaRI as the sole receptor for IgG3 immune complexes. Competition studies demonstrated that monomeric mouse IgG3 could inhibit IgG2a binding to mouse Fc gammaRI with an ID50 approximately 10(-7) M (fivefold lower than IgG2a). The identification of mouse Fc gammaRI as the IgG3 receptor establishes Fc gammaRI as a participant in events at the interface between innate and adaptive immunity, implying a greater role for this receptor in the development of normal and pathologic immune responses than previously recognized.
Inhaled corticosteroids are the main treatment for controlling asthma in adults and children. However, there is still some concern over the safety of these drugs when used at high doses and for long periods of time. Hence issues relating to the efficacy and safety of inhaled corticosteroids have been extensively researched over the past 5 years. General considerations, such as use of an appropriate dose of inhaled corticosteroid in an appropriate asthma population, are discussed. Studies comparing the efficacy and safety of fluticasone propionate, beclomethasone dipropionate, and budesonide are highlighted, and a systematic review of these studies suggests that fluticasone propionate has a better efficacy:safety therapeutic ratio than either beclomethasone dipropionate or budesonide.
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Children who are too ill to await a liver graft of suitable size may be transplanted with a relatively oversized graft by leaving the abdominal wound partially open, the defect reduced being bridged with polypropylene mesh and the mesh reduced in stages until it can be removed and the wound directly closed. This technique has been used in seven children who received nine grafts (five reduced and four full size). Their mean age was 7.3 (range 0.5-11) months and mean weight 5.8 (range 2.3-7.2) kg. Progressive reduction in the size of the transplanted liver made primary closure possible in survivors in up to four stages. Over a follow-up period of 3 to 58 months, five of the nine grafts and five of the seven patients survived. No significant complications attributable to the technique were encountered. The technique of delayed primary abdominal wall closure may be of benefit in children at risk of graft failure because of a size-mismatched graft.
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A review of 21 cases of patients with spinal tuberculosis has been performed, with special attention being paid to methods of diagnosis and the surgical treatment undertaken. We found that the clinical presentation of the condition was often similar to that of malignant disease within the spine, with the commonest presenting features being back pain (95%), an evaluated erythrocyte sedimentation rate (ESR) (100%) and neurological deficits (47%). The radiological appearances were diagnostic of spinal tuberculosis in less than 50% of cases. Microbiological confirmation of the diagnosis was possible only by direct analysis of tissue or pus, either at operation or from a vertebral biopsy. The difficulty of diagnosing this condition and the implications that this has on the timing and nature of surgery in patients presenting with neurological deficits are discussed.