PubMed Health⌕ Search

Biomedical subjects

Mary Lowery-Nordberg

Publications and source records attributed to Mary Lowery-Nordberg.

5 recordsLinked to original sources
PubMed2006

Iron chelators reduce chromosomal breaks in ataxia-telangiectasia cells.

Ataxia-telangiectasia (A-T) is characterized by ataxia, genomic instability, and increased cancer incidence. Previously, iron chelator concentrations which suppressed normal cell colony formation increased A-T cell colony formation. Similarly, iron chelators preferentially increased A-T cell colony formation following peroxide exposure compared to normal cells. Last, A-T cells exhibited increased short-term sensitivity to labile iron exposure compared to normal cells, an event corrected by recombinant ATM (rATM) expression. Since chromosomal damage is important in A-T pathology and iron chelators exert beneficial effects on A-T cells, we hypothesized that iron chelators would reduce A-T cell chromosomal breaks. We treated A-T, normal, and A-T cells expressing rATM with labile iron, iron chelators, antioxidants, and t-butyl hydroperoxide, and examined chromosomal breaks and ATM activation. Additionally, the effect of ATM-deficiency on transferrin receptor (TfR) expression and TfR activity blockage in A-T and syngeneic A-T cells expressing rATM was examined. We report that (1) iron chelators and iron-free media reduce spontaneous and t-butyl hydroperoxide-induced chromosomal breaks in A-T, but not normal, or A-T cells expressing rATM; (2) labile iron exposure induces A-T cell chromosomal breaks, an event lessened with rATM expression; (3) desferal, labile iron, and copper activate ATM; (4) A-T cell TfR expression is lowered with rATM expression and (5) blocking TfR activity with anti-TfR antibodies increases A-T cell colony formation, while lowering chromosomal breaks. ATM therefore functions in iron responses and the maintenance of genomic stability following labile iron exposure.

Antibodies↗
PubMed2005

Increased transferrin receptor expression following 11q23 deletion as a mechanism of malignant progression in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is a common adult leukemia characterized by the accumulation of mature neoplastic B-lymphocytes. Typically, CLL follows an indolent course, with most patients surviving for many years. However, 10-20% of CLL patients carry 11q23 chromosomal deletions and often exhibit a more severe disease course, with earlier onset of symptoms, shortened lymphocyte doubling time, poor response to therapy, and shortened survival. The molecular basis for 11q23 deletions resulting in a poor prognosis is currently poorly understood. The tumor suppressor gene, ataxia-telangiectasia mutated (ATM, 11q22.3-23.1), is considered a likely candidate gene whose loss could result in the poor prognosis associated with 11q23 deletion and is mutated in a significant percentage of CLL cases. Recently, recombinant ATM expression in ATM-deficient cells was found to decrease transferrin receptor (TfR) expression, suggesting that deletion of the chromosomal region carrying ATM results in increased TfR expression. TfR imports iron into cells, an event necessary for DNA synthesis and cell growth. Additionally, rapidly growing malignant cells, including lymphomas and CLL, often express high TfR levels. Based on this, we propose that one molecular mechanism by which 11q23 deletions confer a poor prognosis in CLL is via increased TfR expression secondary to ATM loss, resulting in the increased cellular iron import, and hence increased capacity for malignant growth. Our hypothesis may also partially explain why gallium, an atomically iron-like toxic metal that binds to transferrin and the TfR is incorporated into cells and was previously demonstrated to have anti-tumor activity in patients with lymphomas refractory to other chemotherapeutic treatments.

Ataxia Telangiectasia Mutated Proteins↗
PubMedDate not supplied

Serratia marcescens osteomyelitis in an infant.

Neutrophil dysfunction can result from oxidative burst defect or from glucose-6-phosphate dehydrogenase (G6PD) deficiency; we noted both in the same patient. A 4-month-old male infant with G6PD deficiency presented with swelling of the left middle finger, left leg, and right big toe. At 5 weeks of age he was hospitalized for fever for 2 days. A maternal uncle died at 5 years of age and a male maternal cousin died at the age of 21 months, both reportedly diagnosed with chronic granulomatous disease (CGD). On physical examination, he had a swollen erythematous left third finger, left distal leg swelling, and right big toe abscess. None of these areas was significantly tender. WBC was 18.7 x 10(3)/mm(3) with 37% PMN and 5% bands. The x-ray films showed osteomyelitis in the left third proximal phalanx and the distal right first metatarsal. Culture from the toe abscess grew Serratia marcescens. His neutrophil oxidative burst was tested by the dihydrorhodamine-123 assay and was markedly suppressed, typical of CGD. The mother and maternal grandmother were found to be CGD carriers. He was treated with i.v. antibiotics for 4 weeks and was discharged on prophylactic trimethoprim, itraconazole and interferon gamma, with substantial reduction in infections. Infection in this infant was unusual in its nature, in affecting multiple sites, and in its causative organism. Immune deficiency was suspected, particularly of the phagocytic component, but could not be attributed to his moderate degree of primary G6PD deficiency. Additional immunologic evaluation and the family history led to the diagnosis of X-linked CGD.

Chromosomes, Human, X↗
PubMedDate not supplied

Immune defects in subjects with dysmorphic disorders.

Patients with dysmorphic disorders seem to have frequent respiratory infections that may be attributed to associated anatomic or neurological abnormalities, but immune defects may contribute to their susceptibility to infections. We screened subjects with dysmorphic conditions for major hematologic, B-cell and T-cell defects. We studied 84 subjects with dysmorphic disorders: 29 with chromosomal disorders, 27 with single gene disorders, and 28 with unclassified dysmorphic disorders. They were evaluated by physical examination; medical history suggestive of possible immune deficiency; complete blood count; serum immunoglobulin G (IgG), IgA, and IgM levels; and lymphocyte subsets. Low laboratory values (less than fifth percentile for age) were detected in 54.8%; was highest in the chromosomal disorder group (79.3%) followed by the single gene disorder group (55.6%) and was lowest in the unclassified dysmorphic disorder group (28.6%). The most common low values were in the CD19 and CD16/56 lymphocyte subpopulations followed by IgG and IgA levels. None of the subjects had neutropenia or thrombocytopenia. History of significant recurrent infections was noted in five subjects, all of whom had abnormal laboratory values. The highest frequency of abnormal laboratory values was in Down syndrome followed by Turner syndrome and chromosome deletions. We concluded that patients with dysmorphic disorders, particularly those with chromosomal disorders, have a high frequency of various B-cell and T-cell defects that may be contributing to their susceptibility to infection. Studies are needed to further delineate the immunologic defects in that population and to investigate a possible genetic basis at the molecular level.

Adolescent↗