Methylation analysis of the neurofibromatosis type 1 (NF1) promoter in peripheral nerve sheath tumours.

Peripheral nerve sheath tumours are hallmarks of neurofibromatosis type 1 (NF1). Development of plexiform neurofibromas to malignant peripheral nerve sheath tumours (MPNST) is common. The NF1 gene promoter harbours a hypomethylated CpG island. Thus, methylation changes may be involved in the development of different types of neurofibromas and malignant transformation. We investigated NF1-associated dermal (n=9) and plexiform neurofibromas (n=7), MPNST (n=5) and non-NF1 leucocyte samples (n=20) for their methylation pattern by bisulphite genomic sequencing. We could not find global hypermethylation in the NF1 promoter in our series. Nevertheless, site-specific methylation, involving transcription factor binding sites for SP1, CRE (-10), and AP-2, was observed. One region of the 5'-UTR (untranslated region) overlapping with a putative AP-2 binding site was methylated at 30-100% in 4/20 control samples. In conclusion, we did not find hypermethylation in NF1-associated tumours. Instead, low level methylation could parallel a global genomic hypomethylation in malignancy.

Clinically significant allo-anti-I in an I-negative patient with massive hemorrhage.

A 37-year-old white man who had never been transfused was admitted as an emergency patient with a ruptured spleen and a falling hematocrit (19% on admission). All crossmatches were incompatible. His serum contained anti-I, and his red cells (RBCs) were I-negative and strongly i-positive. Only 4 units of crossmatch-compatible I-negative frozen RBCs were available immediately. Because of the likelihood that more than 4 units would be required, chromium survival studies were performed using I-positive cells. Samples obtained at 15 and 30 minutes after injection revealed less than 1 percent survival of the donor RBCs. He received the 4 units of I-negative RBCs during the operation in addition to reinfusion of RBCs harvested from 1800 ml of blood aspirated from the abdominal cavity. The postoperative hematocrit remained greater than 30 percent and the bilirubin less than 1.5 mg per dl. Before recommending frozen storage of autologous RBCs, 51Cr labeled I-positive RBCs from the patient's daughter (obligate li heterozygote) were infused. Survival was 100 percent at 15 and 30 minutes, 90 percent at 3 hours, 85 percent at 26 hours; the remaining RBCs disappeared at a normal rate (T 1/2 27 days) over the succeeding 2 weeks. A repeat 51Cr-labeled RBC study with the original I-positive donor confirmed greater than 92 percent destruction in 90 minutes. The clinical significance of this allo-anti-l (apparently primarily against RBCs from homozygous I-positive donors) is in marked contrast to reported findings with auto-anti-l antibodies.

Long-term in vivo survival of Rh(D)-negative donor red cells in a patient with anti-LW.

The present study documents immediate and long-term survival of crossmatch-incompatible Rh(D)-negative donor red cells in a patient with anti-LW. A 67-year-old group A Rh(D)-positive man was admitted for urgent coronary artery bypass surgery. The direct antiglobulin test (DAT) was weakly positive in two of five laboratories. His serum contained anti-LW (two laboratories); his red cells were LW negative (three antisera). Two siblings were LW-positive. Surgery was delayed, and 3 ml Rh(D)-negative crossmatch-incompatible red cells stored in citrate-phosphate-dextrose-adenine-one were labeled with 25 microCi of 51Cr and injected. Immediate survival was approximately 100 percent with 92 percent survival at 20 hours. Six daily blood samples showed a decreased red cell lifespan, (T 1/2 = 14 days). Because of medical complications, 4 units of Rh(D)-negative crossmatch-incompatible blood were then transfused without clinical or hemolytic reaction. The anti-IgG DAT became stronger. In vivo survival of the remaining 51Cr-RBCs became normal (T 1/2 28 days over the succeeding 20 days). Following transfusion, no change in serum antibody strength was demonstrated by double-blind titration of seven coded samples. The observations support modest reduction of lifespan for 3 ml of LW-positive red cells, but normal survival following subsequent transfusion of approximately 700 ml of LW-positive red cells.

The efficacy of type and screen to reduce unnecessary cross matches for obstetric patients.

A type-and-screen procedure was established whereby obstetric patients with no complications would be tested for ABO, Rh, and unexpected antibody. If the antibody screen was negative, cross matches would not be performed. Type and screen could be converted in 20 minutes to cross match, or type-specific blood would be immediately available. Our initial results with type and screen demonstrated 65.5% utilization but 399 cross matches were done for 17 transfusions (cross match/transfusion ratio of 17.6/1). The protocol was changed so that all nonbleeding patients would be typed and screened. A total of 503 of the next 563 patients (89.3%) were typed and screened; cross matches provided 33 transfusions (cross match/transfusion ratio of 4.9/1). An estimated 964 cross matches were eliminated with cost savings of $14,460 in 3 months. We concluded that the type-and-screen procedure is an effective tool in reducing the cross match/transfusion ratio and in lowering costs in obstetric patients with no compromise in patient care, even in high-risk patients.