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N T Shahidi

Publications and source records attributed to N T Shahidi.

At least 19 recordsLinked to original sources
PubMed1995

Plasma/serum levels of flt3 ligand are low in normal individuals and highly elevated in patients with Fanconi anemia and acquired aplastic anemia.

The flt3 ligand is a growth factor that stimulates the proliferation of hematopoietic progenitor and stem cells. We established a sensitive enzyme-linked immunosorbent assay (ELISA) to measure the concentration of flt3 ligand in plasma or serum from normal individuals, as well as in patients with hematopoietic disorders. Concentrations of flt3 ligand in plasma or serum from normal individuals were quite low: only 12% (7 of 60) of normal individuals had flt3 ligand levels above 100 pg/mL (the limit of detection). In contrast, 86% (19 of 22) of samples from patients with Fanconi anemia and 100% (eight of eight) of samples from patients with acquired aplastic anemia had plasma or serum levels above 100 pg/mL. Mean plasma or serum concentrations (calculated by assigning a value of 0 pg/mL to any sample reading below the level of detection) were as follows: normal volunteers, 14 pg/mL; patients with Fanconi anemia, 1,331 pg/mL; and patients with acquired aplastic anemia, 460 pg/mL. Concentrations of flt3 ligand in blood are, therefore, specifically elevated to a level that may be physiologically relevant in hematopoietic disorders with a suspected stem cell component. The elevated flt3 ligand concentrations in these individuals may be part of a compensatory hematopoietic response to boost the level of progenitor cells.

Anemia, Aplastic↗
PubMed1995

Fetal hemoglobin expression in transplant recipients of placental blood hematopoietic progenitor cells.

Patients who achieved bone marrow engraftment of cord blood-derived progenitor cells provided an opportunity to examine the expression of fetal Hb by neonatal hematopoietic progenitors in a postneonatal host. Cord blood cells from histocompatible siblings were successfully transplanted in two children with the Fanconi anemia syndrome. One of the transplant donors had heterocellular hereditary persistence of fetal Hb, apparently due to gamma-globin gene triplication; the other donor was hematologically normal. The G gamma/A gamma ratio of the patient who received his transplant from the donor with hereditary persistence of fetal Hb was markedly elevated, similar to that of the transplant donor's cord blood, and this ratio remained elevated in subsequent months. In the other child, the G gamma/A gamma ratio immediately after her transplant was typical of the normal newborn, and over the next several months it reverted to the adult pattern. Globin synthesis studies performed shortly after engraftment demonstrated ratios of fetal Hb/adult Hb synthesis in both patients that were typical of those of normal newborns. Over the next several months, both patients converted to the adult pattern. Fetal Hb to adult Hb switching in these patients seemed to follow a temporal sequence intrinsic to the transplanted neonatal progenitor cells, without discernible influence of postneonatal environmental factors. The program for Hb switching seems to be an inherent feature of neonatal hematopoietic progenitor cells.

Fanconi Anemia↗
PubMed1994

Establishment of an adherent cell feeder layer from human umbilical cord blood for support of long-term hematopoietic progenitor cell growth.

Previous attempts to establish a stromal cell feeder layer from human umbilical cord blood (HUCB) have met with very limited success. It has been suggested that there is an insufficient number of stromal precursor cells in HUCB to form a hematopoietic-supporting feeder layer in primary cultures. The present study shows that HUCB does contain a significant accessory cell population that routinely develops into a confluent, adherent cell layer under defined primary culture conditions. HUCB-derived adherent layers were shown to support long-term hematopoietic activity for an average of 4 months. This was achieved by using a customized coverslip with a modified surface structure as the cell attachment substratum and using a specialized culture feeding regime. We have characterized the various cell types (including fibroblasts, macrophages, and endothelial cells) and extracellular matrix proteins (including fibronectin, collagen III, and laminin) that were present in abundance in the HUCB-derived adherent cell layer. In contrast, oil red O-staining fat cells were rarely detected. ELISA and bioassays showed that stem cell factor and interleukin 6 were produced by the HUCB stromal cell cultures, but interleukin 3 or granulocyte/macrophage colony-stimulating factor was not detected. Application of this hematopoietic culture system to transgenic and gene therapy studies of stem cells is discussed.

Antigens, CD↗
PubMed1993

Haemopoietic stem/progenitor cell transplant in Fanconi anaemia using HLA-matched sibling umbilical cord blood cells.

There have only been a few reports documenting the use of umbilical cord blood as a source of stem cells for haemopoietic reconstitution. We report our experience with a child with Fanconi anaemia (FA) who underwent a stem cell transplant using umbilical cord blood cells from his HLA matched sibling. Although the engraftment was somewhat slow, it was complete and comparable to other transplants performed in FA patients using HLA matched sibling marrow. There was no graft-versus-host disease. The post-transplant period was uncomplicated and, at a follow-up of 36 months, this child is well with normal blood counts and immune function.

Child, Preschool↗
PubMed1991

Synergistic and antagonistic effects of combinations of cyclosporine A and its metabolites on inhibition of phytohemagglutinin-induced lymphocyte transformation in vitro.

Cyclosporine A (CsA) and purified CsA metabolites were tested alone and in combination in cell culture to determine their effects on phytohemagglutinin (PHA)-induced lymphocyte proliferation. CsA was significantly more inhibitory than its metabolites at all concentrations tested (0-1000 ng/mL). CsA exerted maximum inhibition (70% decrease in [methyl-3H]thymidine incorporation) at concentrations of 300 ng/mL or greater; metabolites M1, M17, and M21 depressed the response 46, 39, and 23%, respectively, at 300 ng/mL. Metabolites M8, M18, M26, M25, M13, and M203-218 were non-inhibitory. When combinations of M17 and CsA were tested for the effects on PHA-induced lymphocyte transformation, a synergistic effect occurred at combinations of low concentrations of M17 and CsA and an antagonistic effect at the higher concentrations. Of the 49 combinations of CsA and M17 tested, 30 were antagonistic, 16 synergistic and 3 undecided (approaching addition). When 49 combinations of CsA and the non-immunosuppressive metabolite M8 were tested, 29 of the 49 combinations were synergistic, 17 antagonistic, 1 additive and 2 undecided (approaching addition). Of the 29 synergistic combinations, 14 were strongly synergistic. The importance of the interaction of CsA and metabolites to the immunopharmacology of CsA therapy is discussed.

Cell Division↗
PubMed1991

Benign familial thrombocytosis.

A 13-year-old girl was found to have a platelet count in excess of 4 million/microliters while being evaluated for a minor bleeding episode. Her father and two sisters also had thrombocytosis. All four affected patients were asymptomatic and had no clinical or laboratory evidence of a myeloproliferative disorder other than an elevated platelet count. This represents the second reported instance of benign familial thrombocytosis.

Adolescent↗
PubMed1987

Fanconi anemia, dyskeratosis congenita, and WT syndrome.

The association of congenital anomalies and pancytopenia is encountered in several clinical syndromes. Among these, Fanconi anemia is by far the most prevalent, and consequently best known. As a result, other similar conditions, such as dyskeratosis congenita and particularly WT syndrome, are often mistaken for Fanconi anemia. However, at a closer look, the type of congenital anomalies, the mode of inheritance, cytogenic and other laboratory findings allow clear differentiation between these 3 syndromes.

Abnormalities, Multiple↗
PubMed1987

Haploidentical bone marrow transplantation for osteopetrosis.

HLA-matched bone marrow transplantation is an effective form of treatment for some patients with malignant osteopetrosis, a defect of osteoclast function. Following transplant, normal osteoclasts differentiate from donor-derived marrow stem cells and can function normally in some of these patients. For patients without an HLA-matched marrow donor, pharmacologic treatments have not yet proved effective. This article demonstrates that normal osteoclast function can be obtained following the transplantation of HLA-nonidentical marrow that has been purged of T lymphocytes in vitro.

Antilymphocyte Serum↗
PubMed1986

Effects of recombinant human interferon gamma on hematopoietic progenitor cell growth.

Human bone marrow BFU-E, CFU-E, and CFU-GM were cultured in the presence of varying concentrations of recombinant human interferon gamma (rHuIFN-gamma). Concentration-dependent inhibition of both erythroid and myeloid precursors by rHuIFN-gamma was demonstrated. A more pronounced suppressive effect of rHuIFN-gamma was seen on the BFU-E than on the CFU-E, with CFU-GM most resistant. rHuIFN-gamma was also added at varying time points during the marrow cultures, demonstrating different time-dependent sensitivities to rHuIFN-gamma; CFU-E were no longer sensitive to rHuIFN-gamma by day 2 of culture, BFU-E by day 6, and CFU-GM by day 9, indicating a loss of sensitivity with maturation. Finally, exposure of marrow cells to rHuIFN-gamma for varying periods of time prior to initiation of hematopoietic cultures failed to inhibit erythroid colony growth in the absence of rHuIFN-gamma in the culture. These studies demonstrate a suppressive effect of rHuIFN-gamma on human erythroid and myeloid progenitor cell growth. This effect appears to be most pronounced on the more primitive stages of committed progenitor cell development.

Bone Marrow↗
PubMed1985

The role of aminocaproic acid in lacrimal surgery in dyskeratosis congenita.

A 14-year-old boy with bilateral epiphora since birth had absent lacrimal puncta, oral leukoplakia, agenesis of the nails, cutaneous dyschromia, and pancytopenia, findings noted in the rare syndrome of dyskeratosis congenita. Bilateral conjunctivodacryocystorhinostomy was complicated by persistent hemorrhage despite preoperative platelet transfusion. The hemorrhage was controlled by administration of an antifibrinolytic agent, aminocaproic acid. Lacrimal excretory anomalies may be the initial manifestation of a serious systemic disorder, dyskeratosis congenita. Surgical management in this disorder should include appropriate hematologic support.

Adolescent↗
PubMed1985

Angiosarcoma of the liver and spleen in an infant.

A 14-month-old white male was diagnosed as having angiosarcoma of both the liver and spleen. At 17 months he developed pulmonary metastases and died. There was no apparent environmental or hormonal exposure either prenatally or during infancy. The malignant tumor probably arose from its benign counterpart (hemangioendothelioma), which was found in the spleen. This is the fifth case reported of splenic angiosarcoma in the pediatric age group (18 years or younger).

Adolescent↗