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J Kelton

Publications and source records attributed to J Kelton.

9 recordsLinked to original sources
PubMed1996

A simple and rapid competitive enzyme-linked immunosorbent assay to identify HPA-1a (PlA1)-negative donor platelet units.

BACKGROUND: Alloantibodies to HPA-1a (PlA1) are the major cause of neonatal alloimmune thrombocytopenia and posttransfusion purpura and have been implicated in refractoriness to random-donor platelet transfusions. However, most assays used to phenotype platelets are cumbersome or time-consuming for large numbers of samples. STUDY DESIGN AND METHODS: A simple, competitive (inhibition) enzyme-linked immunosorbent assay for HPA-1a phenotyping of donor platelets was developed. A segment from the donor platelet unit transfer line was sealed to obtain a small aliquot of platelets. These platelets were washed once and added to a predetermined dilution of serum containing alloantibodies to HPA-1a. Residual anti-HPA-1a binding to the glycoprotein IIb/IIIa purified by lectin and high-performance liquid chromatography and coated on microtiter wells was detected with a conjugated antihuman IgG. A lack of inhibition equivalent to control (no platelets) was used to determine that the platelets were HPA-1b/b. RESULTS: Of the 557 platelet units tested, 14 (2.5%) were found to be HPA-1a negative, and they were confirmed to be HPA-1b/b by DNA genotyping. Two of the 14 HPA-1b/b units were also HPA-3b/b (approx. 0.35% of the random population). Use of the microtiter format allows 100 to 200 samples to be processed per day. CONCLUSION: This simple and inexpensive assay is useful for identifying HPA-1b/b units for platelet-compatible transfusions or for platelet antibody investigations.

Antigens, Human Platelet↗
PubMed1992

Thrombotic thrombocytopenic purpura: outcome in 24 patients with renal impairment treated with plasma exchange. Canadian Apheresis Study Group.

The Canadian Apheresis Study Group recently completed a randomized clinical trial involving 102 patients with thrombotic thrombocytopenic purpura (TTP), in which treatment with plasma infusion and treatment with plasma exchange were compared. Thirty-three other patients were ineligible or refused to be randomly assigned in the trial. Of the 33 patients, 24 were assessed as ineligible because they would be unable to tolerate the fluid input that would occur if they were randomly assigned to receive plasma infusion. All 24 patients had oliguria and elevated creatinine and/or blood urea nitrogen level. These 24 patients were treated with acetylsalicyclic acid, dipyridamole, and plasma exchange according to the standardized protocol defined in the trial. Blood for tests of factors possibly involved in the pathogenesis of TTP was drawn before exchange and at intervals during and after exchange. The mean platelet count before exchange was 35.5 x 10(9) per L. In 12 of the 24 patients, the platelet count reached 150 x 10(9) per L or greater by 7 days after the initiation of plasma exchange. Three patients responded partially, in that their platelet count increased to at least twice that at presentation, but remained below 150 x 10(9) per L. One patient died during the first week. Of the eight other patients who experienced treatment failure at the 7-day assessment point, six subsequently responded, four while continuing to receive plasma exchange and two after plasma exchange had been discontinued. Of the 15 patients who either responded fully or responded partially by the end of the first cycle, all survived.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Frequency and mechanism of neonatal thrombocytopenia.

We performed a 1-year prospective study of 807 consecutive infants admitted to a regional neonatal intensive care unit to determine the frequency, natural history, mechanism(s), and cause of thrombocytopenia. Thrombocytopenia developed in 22% of the infants. The platelet count nadir usually occurred by day 4 and resolved by day 10. Possible mechanisms responsible for the thrombocytopenia were assessed by comparing mean platelet volume, platelet-associated IgG (PAIgG), and coagulation test results in those infants whose platelet count fell below 100 X 10(9)/L (n = 97) with values in age-, weight-, and disease-matched control infants without thrombocytopenia (n = 80). In some thrombocytopenic infants, 111In-labeled-platelet survival, an estimate of megakaryocyte number in bone marrow biopsy specimens obtained at autopsy, and response to platelet infusions were also assessed. The thrombocytopenia was caused by increased platelet destruction, as shown by short 111In-labeled-platelet survival (12 to 128 hours), a rising mean platelet volume during the first week of life, normal numbers of megakaryocytes, and a poorer than predicted response to platelet infusions. A potential cause for the thrombocytopenia could be found in the majority of infants: 52% had elevated levels of PAIgG, 21% had laboratory evidence of disseminated intravascular coagulation, and 12% had had exchange transfusions. In contrast, the control infants had normal coagulation assay results, and only 15% had elevated levels of PAIgG. Birth asphyxia was identified as an associated risk factor for thrombocytopenia. This study demonstrates that transient, destructive thrombocytopenia develops in a large proportion (22%) of infants admitted to a neonatal intensive care unit, and that birth asphyxia is an important risk factor.

Asphyxia Neonatorum↗
PubMed1984

Neonatal thrombocytopenia.

In this well-detailed review, the authors review the contribution of platelets to hemostasis, diagnostic approaches to the thrombocytopenic infant, and the classification and treatment of neonatal thrombocytopenia.

Anemia, Aplastic↗
PubMed1978

A rapid method for the diagnosis of acute uric acid nephropathy.

Acute uric acid nephropathy is a reversible type of renal failure that results from the deposition of uric acid crystals in the collecting tubules. The present study has compared a number of laboratory tests in 5 patients with a clinical diagnosis of this disorder and 27 patients with acute renal failure of other causes. Neither the serum creatinine, BUN, serum urate concentrations, nor the ratio of serum urate:BUN differentiated between these two groups of patients. However, the ratio of uric acid to creatinine concentration on a random urine specimen did differentiate between these two patient populations. All patients with uric acid nephropathy had a ratio greater than 1.0, while all patients with other types of acute renal failure had ratios of less than 1.0.

Acute Kidney Injury↗