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Biomedical subjects

D Rucknagel

Publications and source records attributed to D Rucknagel.

8 recordsLinked to original sources
PubMed1996

Pre- and post-stroke MRI and neuropsychological studies in sickle cell disease: a case study.

The case of a patient with sickle cell disease is presented in which neuropsychological and magnetic resonance imaging studies were completed prior to and after a right hemispheric stroke. The contribution of a new MR perfusion technique in understanding the neurological complications in this patient is discussed. This case illustrates the complex pathophysiology of neuropsychological deficits in SCD and underscores the need to develop models that better reflect this complexity.

Journal Article↗
PubMed1995

Bone marrow transplantation in a young child with sickle cell anemia.

Bone marrow transplantation (BMT) is the only curative therapy available for hemoglobinopathies. BMT was performed on a young child with sickle cell anemia (SCA) after approximately 9 months of transfusion therapy following her initial stroke. The patient received a matched sibling donor (sickle trait) BMT. The conditioning regimen consisted of busulfan 4 mg/kg/day x 4, cyclophosphamide 50 mg/kg/day x 4. Graft vs. host disease prophylaxis was daily cyclosporine for 6 months. There were no significant complications during BMT. Engraftment occurred on day +17 and the patient was transfusion independent since day +45. Pre-BMT cerebral arteriography showed multiple stenotic cerebral vessels and a moya-moya pattern. Perfusion MRI demonstrated reduced capillary perfusion. Approximately 170 days after BMT the patient experienced episodes of transient left-sided weakness and speech problems. Neuroimaging revealed progression of large vessel pathology by angiography despite significant improvement in cortical perfusion (MR perfusion scan). Molecular analysis by PCR and DNA fingerprinting confirmed absence of mixed mosaicism. Rheologic evaluation showed normal corrected bulk viscosity. It is possible that progression of large vessel pathology and return of clinical symptoms in the face of normal rheologic parameters may be due to worsening of the already damaged cerebral vessels by the BMT conditioning regimen. Further evaluations of patients with SCA undergoing BMT after a stroke are needed to answer this question.

Anemia, Sickle Cell↗
PubMed1994

Sarcoidosis in a child with sickle cell anemia.

PURPOSE: The purpose of this case report is to (a) present a detailed description of a child with sickle cell anemia who developed sarcoidosis, (b) compare the clinical aspects of sickle cell anemia and sarcoidosis, and (c) review the literature with respect to the coincidence of these two diseases. Detailed clinical case history and laboratory findings are presented. A literature review of other case reports with children and adults who have both sickle cell anemia and sarcoidosis is given. RESULTS: Based on limited data, there may be an increased incidence of sarcoidosis in adults with sickle cell diseases. No data are available in the pediatric population. CONCLUSIONS: Sarcoidosis is difficult to diagnose in children with sickle cell anemia. The clinical manifestations of sickle cell anemia and sarcoidosis have overlapping features but represent distinct syndromes. Patients with sickle cell anemia who have unusual signs and symptoms need to be further evaluated for the possibility of other coincident diseases, including sarcoidosis.

Anemia, Sickle Cell↗
PubMed1992

Regulation of oxygen affinity by quaternary enhancement: does hemoglobin Ypsilanti represent an allosteric intermediate?

Recent crystallographic studies on the mutant human hemoglobin Ypsilanti (beta 99 Asp-->Tyr) have revealed a previously unknown quaternary structure called "quaternary Y" and suggested that the new structure may represent an important intermediate in the cooperative oxygenation pathway of normal hemoglobin. Here we measure the oxygenation and subunit assembly properties of hemoglobin Ypsilanti and five additional beta 99 mutants (Asp beta 99-->Val, Gly, Asn, Ala, His) to test for consistency between their energetics and those of the intermediate species of normal hemoglobin. Overall regulation of oxygen affinity in hemoglobin Ypsilanti is found to originate entirely from 2.6 kcal of quaternary enhancement, such that the tetramer oxygenation affinity is 85-fold higher than for binding to the dissociated dimers. Equal partitioning of this regulatory energy among the four tetrameric binding steps (0.65 kcal per oxygen) leads to a noncooperative isotherm with extremely high affinity (pmedian = .14 torr). Temperature and pH studies of dimer-tetramer assembly and sulfhydryl reaction kinetics suggest that oxygenation-dependent structural changes in hemoglobin Ypsilanti are small. These properties are quite different from the recently characterized allosteric intermediate, which has two ligands bound on the same side of the alpha 1 beta 2 interface (see ref. 1 for review). The combined results do, however, support the view that quaternary Y may represent the intermediate cooperativity state of normal hemoglobin that binds the last oxygen.

Allosteric Regulation↗
PubMed1986

Sickle-cell nephropathy: MR imaging.

To study the nephropathy associated with sickle-cell disease (SCD), spin-echo magnetic resonance (MR) imaging of the kidneys was performed in 19 SCD patients, six with beta-thalassemia major (BTM), and ten healthy individuals as controls. Eleven SCD patients had decreased relative cortical signal, most evident on T2-weighted images. No correlation with serum ferritin, urine-concentrating ability, serum blood urea nitrogen, or creatinine levels was established. Iron deposition in the renal cortices of sickle-cell nephropathy patients may, at least in part, be responsible for the relatively diminished cortical signal intensity. No BTM patients, all of whom were clinically and biochemically in iron overload from frequent transfusions, demonstrated diminished renal cortical signal intensity. This suggests that renal changes in SCD seen on MR images are not due simply to systemic iron overload per se but perhaps reflect abnormalities of iron metabolism in the renal cortex peculiar to SCD nephropathy.

Adolescent↗
PubMed1980

Development of a somatic mutation screening system using Hb mutants. IV. Successful detection of red cells containing the human frameshift mutants Hb Wayne and Hb Cranston using monospecific fluorescent antibodies.

The production and purification of antibodies detecting Hb Wayne, an alpha-globin frameshift mutant, and Hb Cranston, a beta-globin frameshift mutant, are described. The antibodies are of a nonprecipitating nature, and they permit strong fluorescent labeling of erythrocytes containing Hb Wayne or Hb Cranston. Studies using artificial mixtures containing cells with either of the two mutants in frequencies ranging from 1 in 10(2) to 1 in 10(5) showed that fluorescent antibodies can detect rare mutant red cells in the presence of vast excesses of normal erythrocytes. On the basis of the structures and the molecular lesions underlying production of the two abnormal hemoglobins, we predict that the anti-Hb Wayne antibody will detect several frameshift mutants resulting from deletion of 3n + 1 nucleotides or insertion of 3n + 2 nucleotides at the 5' side of the codon normally specifying residue 139 of the alpha chain. The anti-Hb Cranston antibody should be capable of detecting beta chains, the corresponding genes of which have sustained insertions of 3n + 2 nucleotides or deletions of 3n + 1 nucleotides on the 5' side of the codon normally specifying residue 144. The two antibodies may, therefore, prove to be valuable in the development of a system aimed at detecting rare erythrocytes that express mutations which arise in the hemopoietic stem cells of normal individuals and subjects exposed to mutagens.

Antibodies↗