WELDING FILTERS AND THERMAL DAMAGE TO THE RETINA

Recent experimental determinations by others of the minimum power density of optical radiation (energy intensity) necessary to cause thermal damage to the retina are reviewed. It is concluded that the previously adopted threshold intensity value for exposures of many minutes duration, 1.8 cal/cm²/min (1.25 mJ/mm²/sec) (Clark, 1967), is supported by part of the conflicting evidence reviewed. Since the remaining evidence indicates thresholds that are higher by a factor of ten or more it is desirable that the lowest threshold, i.e. that adopted, should continue to be used for safety reasons and therefore the infra-red transmission limits for welding fitters previously derived are supported.     

The IgG Subclass Distribution of Thyroglobulin Antibody Synthesized in Culture

Thyroglobulin autoantibodies synthesized by Hashimoto lymphocytes in culture and present in serum have been analysed in terms of their IgG subclass distribution. The autoantibodies produced in vitro were frequently IgG4 or IgG1. whether pokeweed mitogen or Epstein-Barr virus was used to stimulate the cultures, and the subclass distribution of these thyroglobulin antibodies was similar to that observed in the patients'serum. It appears therefore that the antibodies synthesized in vitro in response to polyclonal B-cell activators resemble those produced in vivo, and it seems likely that both pokeweed mitogen and Epstein-Barr virus influence the same B-cell precursors of autoantibody-synthesizing celts, albeit by different mechanisms.     

THYROID FUNCTION IN EUTHYROID SUBJECTS WITH AUTONOMOUS THYROID NODULES

The biochemical abnormalities in euthyroid subjects with autonomous thyroid nodules have been defined. Seven subjects have been studied in detail. None were hyperthyroid and conventional tests of thyroid function were normal. The characteristic abnormalities were noted on scanning. The absent response to TRH demonstrated that pituitary TSH suppression was present in all subjects. A moderate elevation of serum triiodothyronine (T₃) concentration, 1.89-3.07 ng/ml, was noted. It is concluded that autonomous nodules in the euthyroid subjects studied are associated with elevated T₃ levels sufficient to produce pituitary suppression but not high enough to be associated with the clinical manifestations of hyperthyroidism.     

Synthesis of [1, 6-cyclo(Acetyl-1-L-glutamic acid, 2-D-phenylalanine, 3-D-tryptophan, 6-D-lysine)] luteinizing hormone-releasing hormone on poly-N-acrylylpyrrolidine resin

The protected peptide, Ac-Glu(OBu^t)-D-Phe-D-Trp-Ser(Bu^t)-Tyr(Bu^t)-D-Lys(Z)-Leu-Arg(Tos)-Pro-Gly-NH₂ was synthesized in a stepwise manner on a resin of poly-N-acrylylpyrrolidine using both acid cleavable N^α-tert.-butyloxy-carbonyl and base cleavable N^α-fluorenylmethyloxycarbonyl protecting groups. After cleavage by ammonolysis in methanol, the tert.-butyl and benzyloxy-carbonyl side-chain protecting groups were cleaved with CF₃-CO₂H-thioanisole and the 1–6 amide ring formed by cyclization with diphenylphosphorylazide, after which the remaining tosyl protecting group was cleaved in HF-anisole. [1,6-Cyclo (Ac-Glu¹, D-Phe², D-Trp³, D-Lys⁶] LH-RH exhibited less than 10% of the antiovulatory potency of [D<Glu¹, D-Phe², D-Trp^3,6] LH-RH, a potent linear antagonist.     

Consensus approaches to best practice management of gastrointestinal stromal tumors

Gastrointestinal stromal tumors are rare mesenchymal tumors of the gastrointestinal tract. Progress in diagnosis has led to increased recognition of this disease, and the availability of effective, molecularly targeted therapy has revolutionised its management. Treatment of metastatic gastrointestinal stromal tumors with imatinib has led to unprecedented improvements in progression free and overall survival and there are ongoing investigations into the optimal pre‐operative and adjuvant use of imatinib. Second‐line sunitinib is now available for patients who develop resistance to imatinib, and third‐ and fourth‐line therapies are being investigated in clinical trials. In this ever‐changing environment, evidence from controlled clinical trials and the authors' experience were used to comprehensively outline current best practice management of patients with gastrointestinal stromal tumors.     

Coronary Sinus Lead Extraction

TYERS, G.F.O., et al .: Coronary Sinus Lead Extraction. Complications are reported more frequently with the implantation of coronary sinus (CS) than other types of leads, and attempts to extract CS leads may also be associated with increased risks. The authors have performed nonthoracotomy lead extraction (LE) since 1981 and maintained a detailed database. By November 2001, 796 leads had been removed from 401 patients. We undertook review of our CS-LE experience to evaluate prevalence, safety, and efficacy. Of 14 patients referred for CS-LE, 7 were treated in the last year. In six the lead had been placed in the CS intentionally, and in eight inadvertently. One recent patient treated with biventricular pacing was septic and died before LE was undertaken. In nine men and four women (mean age 66 years) had one each CS lead and a total of 34 LEs (2.6/patient). Four CS leads had been in place for <6 months (mean 1.5 month), whereas nine had been in place for between 6 months and 27 years. Several LE methods were used, from simple traction to the use of intraluminal locking stylets and powered sheaths. Complete removal of all leads was achieved in all patients. CS-LE required a mean of 13 minutes, including 1.8 minutes of fluoroscopy. There were no serious complications during the procedures, and the mean hospital stay was 4 days. (PACE 2003; 26[Pt. II]:524–526)     

The influence of maternal Lewis,Secretor and ABO(H) blood groups on fetal growth restriction

Summary. Background: Fetal growth restriction (FGR) is associated with thrombosis of the placenta and an increased risk of subsequent vascular disease in the mother and fetus. The products of interactions between ABO(H), Lewis and Secretor genes are also associated with thrombosis and vascular disease risk. Objectives/Methods: A prospective case–control study of mothers with a severe FGR pregnancy (cases, n = 128; controls, n = 288) was performed to determine whether FGR is associated with particular maternal blood groups. Results: No association with ABO(H) status was observed, but FGR was more common in maternal secretors (odds ratio [OR] 1.70, 95% confidence interval [CI] 1.08–2.69) and consequently in those mothers expressing Le(b) on their red cells (OR 1.80, 95% CI 1.15–2.83), with a reduced risk in non‐secretors and those expressing Le(a). Given the association between blood groups and both activated protein C resistance (APCR) and von Willebrand factor (VWF) levels, post hoc pilot studies on first‐trimester APCR and VWF antigen levels and blood group genotypes were performed. No relationship with Lewis or Secretor was observed. Despite this, lower first‐trimester VWF levels were observed in pregnancies subsequently complicated by FGR. Conclusions: This is the first study reporting a relationship between maternal Secretor/Lewis status and FGR. A link between blood groups and FGR is plausible, as both are associated with cardiovascular disease. We observed no relationship between Lewis/Secretor status and VWF or APCR, but this should be confirmed in a larger study. Thus, the mechanism whereby Secretor and/or Lewis influences FGR is unknown.