A series of cases of sudden unexpected post-neonatal deaths from two centres in the UK have been investigated for evidence of mast cell activation using the biochemical markers tryptase and 9 alpha,11 beta-PGF2. Tryptase was selected as a possible marker because it is a component of mast cell secretory granules and, unlike histamine, it is not released from basophils. The prostaglandin 9 alpha,11 beta-PGF2 is an initial and pharmacologically active metabolite of PGD2, the major mast cell-derived cyclooxygenase product. This prostaglandin was chosen to serve as a marker of newly generated mediator release. In the study, unexplained infant deaths were associated with a higher concentration of tryptase in serum compared with cases of unexpected, but subsequently explained death. However, 9 alpha,11 beta-PGF2 was found to be an unsuitable post mortem marker in this situation. These results provide direct evidence that mast cell degranulation, possibly as a result of anaphylaxis, may be occurring around the time of death in some cases of cot death.

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We report a case of histioqtic necrotizing lymphadenitis without granulocytic infiltration (Kikuchi-Fujimoto disease), diagnosed at neeropy in a 1 Pmonth-old child dying unexpectedly after a febnle illness. This is the youngest case with this disease that has been thus f a r reported. It is one ofonly two reported cases in which the patient died during the acute phase of the illness. Histologxal findings not unlike those seen in the lymph nodes were present at extranodal sites; this is thefirst case in which this feature has been described. In keepingwith many otherreported cases, it was not possible to identifjr a n underlying etiology that might explain the morphologic changes.

Methods are presented for the determination by ICP-MS of antimony in body fluids and tissues of infants. Urine, serum and whole blood specimens are prepared for analysis by simply diluting 200 microliters sample volumes (1 + 14) with water and adding indium as internal standard. Liver and lung tissues are digested using 16 M HNO3 either in open quartz vessels at 150 degrees C or in sealed vessels with microwave heating. The acid digests are diluted with water and indium is added as internal standard for ICP-MS measurements. All analyses were subjected to stringent internal quality control protocols. Accuracy was assessed by recoveries, repeated analyses and by analysis of NIST SRMs 1577a Bovine Liver and 1566a Oyster Tissue. Precisions of analyses were better than 5-10% in the ranges 0.1-0.3 microgram l-1 for urine, serum and blood; and at 7-25 ng g-1 in tissues. Detection limits were 0.7 ng g-1 in liver, 0.8 ng g-1 in lung, and 0.01 microgram l-1 in urine, serum and blood. The need to employ validated procedures for specimen collection and to give considerable attention to pre-analytical factors in order to avoid adventitious contamination with antimony is demonstrated.

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