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N Key

Publications and source records attributed to N Key.

7 recordsLinked to original sources
PubMed2001

Kidney retransplants after initial graft loss to vascular thrombosis.

BACKGROUND: Vascular thrombosis early after a kidney transplant is an infrequent but devastating complication. Often, no cause is found. These recipients are generally felt to be good candidates for a retransplant. However, their ideal care at the time of the retransplant and their outcomes have not been well documented. We studied outcomes in 16 retransplant recipients who had lost their first graft early posttransplant (< 1 month) to vascular thrombosis. METHODS: Of 2,003 kidney transplants between I January 1984 and 30 September 1998, we identified 32 recipients who had lost their first graft early posttransplant to vascular thrombosis. Of these 32 recipients, 16 were subsequently retransplanted and detailed chart reviews were done. RESULTS: Of the 16 retransplant recipients, 12 lost their first graft to renal vein thrombosis and 4 to renal artery thrombosis. Thrombosis generally occurred early (mean, 3.6 d). Five recipients underwent a complete hematologic workup to rule out a thrombophilic disorder before their retransplant: 4 had a positive result (presence of antiphospholipid antibodies, n = 3; increased homocysteine levels, n = 1). These 4 recipients, along with 1 other recipient who had a strong family history of thrombosis, underwent thrombosis prophylaxis at the time of their retransplant. Prophylaxis consisted of low-dose heparin for the first 3-5 d posttransplant, followed by acetylsalicylic acid or Coumadin. Of the 16 retransplant recipients, none developed thrombosis. Of the 5 who underwent thrombosis prophylaxis, none had significant bleeding complications. At a mean follow-up of 5.4 yr, 10 (63%) recipients have functioning grafts. Causes of graft loss in the remaining 6 recipients were death with function (n = 5, 31%) and acute rejection (n = 1.6%). Graft and patient survival rates after these 16 retransplants were equivalent to results after primary transplants. The incidence of acute and chronic rejection was also no different (p = ns). CONCLUSION: Vascular thrombosis in the absence of obvious technical factors should prompt a workup for a thrombophilic disorder before a retransplant. Recipients with an identified disorder should undergo prophylaxis at the time of the retransplant. Results in these retransplant recipients are equivalent to those seen in primary transplant recipients.

Chromatography, High Pressure Liquid↗
PubMed2000

Human coagulation factor FVIIa (recombinant) in the management of limb-threatening bleeds unresponsive to alternative therapies: results from the NovoSeven emergency-use programme in patients with severe haemophilia or with acquired inhibitors.

This open-label, emergency-use study evaluated the efficacy and safety of activated human coagulation factor VIIa (recombinant) (rFVIIa) (NovoSeven; Novo Nordisk Pharmaceuticals, Inc., New Jersey, USA) in treating limb-threatening joint or muscle bleeds in 17 patients with haemophilia A or B and six patients with acquired inhibitors to factor VIII or factor IX. All patients had previously failed on one or more alternative therapies. rFVIIa administration was effective or partially effective in controlling joint or muscle bleeds in 34 out of 35 (97%) bleeding episodes; in 23 patients, 14 of 17 (82%) muscle bleeds and 16 of 18 (89%) joint bleeds were effectively controlled. These findings suggest that rFVIIa is an effective and well-tolerated therapeutic option in the management of joint or muscle haemorrhage in patients with haemophilia and in patients with acquired inhibitors.

Adolescent↗
PubMed1996

Lupus anticoagulant and protein S deficiency in children with postvaricella purpura fulminans or thrombosis.

OBJECTIVE: The objective of this study was to determine the cause of purpura fulminans, disseminated intravascular coagulation, or thrombosis in seven children with varicella. All children were found to have a lupus anticoagulant and acquired protein S deficiency. Thrombosis in five children was associated with presumed or documented infection with streptococcus. STUDY DESIGN: Coagulation tests included determinations of the activated partial thromboplastin time, the prothrombin time, the dilute Russell viper venom time, the prothrombin F 1 + 2 fragment, the C4b-binding protein (C4b), total and free protein S antigen, and clotting activities of factors II, V, VII, and X and of protein C and protein S. Autoantibodies to phospholipids, cardiolipin, and protein S were determined in enzyme-linked immunosorbent assays. RESULTS: All children had a lupus anticoagulant and acquired protein S deficiency. Thrombosis in five children was associated with presumed or documented infection with streptococcus. All children transiently expressed free protein S deficiency, elevated levels of IgG, IgM, or both binding to protein S, the lupus anticoagulant, and increased concentration of the F 1+2 fragment. Four children also had antiphospholipid or anticardiolipin antibodies. In one child a purified IgG fraction cross-reacted with both protein S and a specific varicella antigen. CONCLUSIONS: A subset of children with varicella infection, some of whom are coinfected with streptococcus, are prone to development of a lupus anticoagulant and an autoantibody to protein S, which results in acquired free protein S deficiency. Such children are at risk of having life-threatening thrombotic events.

Antibodies, Antiphospholipid↗
PubMed1993

Vascular complications of essential thrombocythaemia: a link to cardiovascular risk factors.

Essential thrombocythaemia (ET) is a myeloproliferative disorder characterized by absolute thrombocytosis and increased incidence of thrombosis and haemorrhage. We report higher morbidity in patients with ET due to arterial ischaemic complications when cardiovascular risk factors are present. In this retrospective analysis of 46 patients, arterial complications occurred in 20/46 patients (43.4%); patients with cardiovascular risk factors, especially cigarette smoking, had more than twice as many arterial complications than patients without risk factors (62.5% v 22.7%, P < 0.05). Neither age, gender nor degree of thrombocytosis were linked to the number of complications. In contrast, we observed no association between cardiovascular risk factors and venous thrombosis or haemorrhagic complications of ET.

Adult↗
PubMed1988

Isolation and immunocytochemical characterization of human bone marrow stromal macrophages in hemopoietic clusters.

Stromal macrophages (M phi) have been localized in situ and isolated within erythroid clusters from human marrow. Stromal M phi arborize in an extensive network uniformly distributed throughout marrow interstitium, and express the phenotype CD4+, CD11a+, CD11c+, CD13+, CD14+, CD16+, CD18+, CD31+, CD32+, FcRI+, HLA-DR+, and CD35-, transferrin receptor-negative, and CD11b (weak). They express endocytic receptor antigens, but show significant differences in myeloid antigen expression compared with freshly harvested or cultured monocytes. Human stromal M phi are therefore specialized mature marrow M phi that are accessible for further investigations in infectious, storage, or hemopoietic disorders.

Antibodies, Monoclonal↗
PubMedDate not supplied

Factor IX inhibitors and anaphylaxis in hemophilia B.

PURPOSE: We present clinical and laboratory data on 18 children from 12 hemophilia treatment centers in the United States, Canada, and Europe with the purpose of disseminating information regarding a recently recognized, potentially life-threatening complication of treatment in very young children with hemophilia B. PATIENTS AND METHODS: Twelve hemophilia centers from the United States, Canada, and Europe provided clinical information and laboratory data concerning 18 children who had severe allergic reactions to infused factor (F) IX in close association with the development of an inhibitor to FIX. Laboratory testing for establishment of the diagnosis of hemophilia B and inhibitor to FIX was done locally at the centers treating these patients. FIX gene analysis was performed at one of six molecular genetics institutes. RESULTS: All 18 children had severe hemophilia B, and in each an inhibitor antibody to FIX developed. The median age at the time of anaphylaxis (or anaphylactoid reaction) was 16 months, and the median number of exposure days to FIX was 11. The FIX inhibitor was detected almost simultaneously with the first occurrence of anaphylaxis in 12 of 18 patients. Maximum inhibitor titers were 4.5-600 Bethesda units (BU), with a median titer of 48 BU. FIX gene analysis, performed in 17 of 18 patients, demonstrated complete deletion of the FIX gene in 10 and major derangements in seven. Immune tolerance induction (ITI) regimens have been attempted in 12 patients, with generally poor responses. Two of the 12 experienced nephrotic syndrome while on ITI. Recombinant FVIIa has been successfully used to treat bleeding episodes in 11 of these children. CONCLUSION: Physicians treating young children with hemophilia B should be aware of the potentially life-threatening complication of anaphylaxis. Children with complete gene deletions or major derangements of the FIX gene appear to be at greater risk. Those identified by genotype as being at greater risk may need to receive their first 10-20 treatments in a medical facility equipped for handling such emergencies. Recombinant FVIIa, although not licensed for use in the United States, appears to be the most suitable treatment option for bleeding episodes in such patients.

Anaphylaxis↗