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Biomedical subjects

N T Shahidi

Publications and source records attributed to N T Shahidi.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1982

Inhibitory effect of leukemic plasma on periodate-induced lymphocyte transformation.

Plasma from nine out of 18 patients with untreated acute lymphoblastic leukemia (ALL) depressed the transformation of normal blood lymphocytes induced by sodium periodate (NaIO4) as judged by reduction of blast cell formation and [3H]thymidine and [3H]uridine incorporation into DNA and RNA respectively. The depressed mitogen responsiveness of lymphocytes cultured in the presence of leukemic plasma was due to the presence of inhibitory factor(s) present in the plasma rather than the absence of components present in normal plasma. The inhibitory effect of leukemic plasma on periodate-induced cell stimulation indicated that the leukemic plasma inhibitory factor(s) exert their action very rapidly and directly on the cell. Transfer of the inhibitory factor(s) from the leukemic plasma to the cultured cells was supported by the finding that the depressive action of leukemic plasma on lectin and non-lectin mitogen-induced transformation of lymphocytes was reduced if the leukemic plasma was preincubated with either resting or mitogen-treated lymphocytes prior to testing with lymphocytes not previously exposed to leukemic plasma or mitogen.

Cell Division↗
PubMed1982

Lymphocyte dysfunction in congenital hypoplastic anemia.

Congenital hypoplastic anemia (Diamond-Blackfan syndrome) is thought to involve the erythropoietic cell line alone. In this study, the evaluation of lymphocyte function in five patients with this syndrome revealed a number of abnormalities. Peripheral blood T lymphocyte percentages as assessed by monoclonal antibodies were decreased in three patients. T-helper/T-suppressor cell (OKT4:OKT8) ratios were almost unity in four of the five patients. We usually find a ratio of 2:1 in normal populations. Studies of lymphocyte-mediated suppression of lymphoproliferation demonstrated an inability to generate concanavalin A-induced suppressor cells in the same four patients and impaired prostaglandin-mediated suppression in two patients. Co-culture studies revealed a T lymphocyte-mediated suppression of erythropoiesis in a single patient, who also showed suppression of the mixed lymphocyte reaction. The four remaining patients showed no excessive suppressor effects either upon erythropoiesis or lymphoproliferation. These studies demonstrate that in congenital hypoplastic anemia, the cellular defect is not restricted to the erythroid progenitor cells, but extends to the lymphocytes.

Adolescent↗
PubMed1981

Mitotic recombination and segregation of satellites in Bloom's syndrome.

Mitotic recombination in satellite stalks--a phenomenon often difficult to distinguish from satellite association--was studied in a sister and a brother with Bloom's syndrome. Segregation after recombination was analyzed in the lymphocytes of the sister who had Q-bright satellites. Her cells varied greatly both in regard to the acrocentrics which displayed Q-bright satellites and the number of such satellites per cell. In 58 cells a total of 31 different patterns were seen. In 83 cells of 6 controls who also had Q-bright satellites on at least one acrocentric chromosome, not one cell was found in which the pattern differed from that characteristic of the person. Obviously exchanges between satellite stalks in patients with Bloom's syndrome are fairly frequent (estimated lower limit 6/1000) and very rare in persons who do not have this syndrome (estimated 0.1/1000).

Chromosome Aberrations↗
PubMed1981

Erythroblastic islands in erythroleukemia.

Erythroblastic islands are distinct anatomical units allowing direct transfer of ferritin molecule into developing erythroblasts. A patient with Fanconi's anemia who developed acute erythroleukemia and hypotransferrinemia exhibited numerous erythroblastic islands in the bone marrow. This unusual finding in our patient is thought to be in response to an increased demand for iron caused by neoplastic erythropoietic proliferation in the absence of an adequate amount of transferrin.

Adolescent↗
PubMed1981

Recategorizing childhood acute lymphoblastic leukemia with monoclonal antibodies to human T cells.

The lymphoblasts of three patients with childhood acute lymphoblastic leukemia (ALL) were analyzed for their immunologic surface markers. Blasts from two of these patients did not form rosettes with sheep erythrocytes and the third did so marginally, suggesting these patients had non-T-cell leukemia. These blasts were also tested with monoclonal antibodies that detect thymocyte differentiation markers, and all three patients were highly reactive with at least two of these reagents. We anticipate the availability of multiple standardized monoclonal reagents will necessitate a recategorization of ALL phenotypes. Some of these leukemic phenotypes may not correspond to normal stages of lymphoid differentiation. Therefore, we suggest that it may be inappropriate to attempt to identify and categorize leukemic cells by the pathways of normal differentiation.

Adolescent↗
PubMed1981

Phlebotomy with iron therapy to correct the microcytic polycythemia of chronic hypoxia.

Patients with chronic hypoxia develop a physiologically appropriate "secondary" polycythemia that improves oxygen carrying capacity. Supplemental iron is often required to maintain this. In severe cases when hematocrit levels approach 70%, iron is withheld in order to avoid dangerously high hematocrit levels and the risks of vascular sludging due to "hyperviscosity." Some patients even require reduction of viscosity by exchange of their polycythemic blood for plasma when symptoms develop. Iron deficiency with microcytic polycythemia can then develop. Management of such patients is unclear. Continued blood withdrawal will worsen the iron deficiency; iron supplementation will increase the hematocrit level and the risks of hyperviscosity. The combination of frequent phlebotomy with oral iron therapy should improve iron stores while safely maintaining a stable hematocrit level in patients with microcytic polycythemia. This combination should also have multiple beneficial effects on tissue oxygen delivery and utilization. This approach has been discussed and used for a patient with microcytic polycythemia due to Eisenmenger syndrome. While on therapy the patient's clinical symptoms decreased, and his serum iron level, hematologic indices, and treadmill tolerance tests all improved.

Administration, Oral↗
PubMed1980

Bone-marrow microenvironment defect in congenital hypoplastic anemia.

An abnormal bone-marrow microenvironment has been thought to have an important role in the pathogenesis of aplastic and hypoplastic anemia in some patients, but direct evidence of such a defect has not been found. We have investigated the pathogenesis of chronic anemia in a young woman. Her bone-marrow cells, obtained by means of aspiration, showed exuberant erythroid growth in methylcellulose despite marked erythroid hypoplasia. The erythroid nature of the colony growth was further confirmed through measurement of heme synthesis and messenger RNA-globin accumulation in a liquid-culture system. In contrast, when whole bone fragments were similarly cultured, no appreciable hemoglobin synthesis was observed. The experimental evidence suggests that, in this patient, hypoplastic anemia resulted from an unfavorable microenvironment.

Adult↗
PubMed1980

A boy with congenital malformations and chromosome breakage.

A patient with increased chromosome breakage and multiple congenital malformations is described. The lack of any apparent quantitative or qualitative disturbance in hemopoiesis and adequate number of myeloid and erythroid progenitor cells and the absence of certain clinical features such as webbed neck and absence of dark pigmentation in the patient did not support the diagnosis of the Fanconi pancytopenia syndrome. The cytogenetic studies revealed increased chromosome breakage at G1 phase, a finding which is also at variance with that observed in patients with the Fanconi pancytopenia syndrome.

Abnormalities, Multiple↗
PubMed1980

Myeloid and erythroid colony growth in non-anaemic patients with Fanconi's anaemia.

Myeloid and erythroid colony growth of the bone marrow and peripheral blood cells from one anaemic and four non-anaemic patients with Fanconi's anaemia were studied. Markedly decreased myeloid and erythroid colony growth was found in all five patients regardless of their haematological status. The decreased colony formation in non-anaemic patients with Fanconi's anaemia is thought to be due to an intrinsic cellular defect.

Adolescent↗
PubMed1980

Inability of intravenously injected monocellular suspensions of human bone marrow to establish in the nude mouse.

Mononuclear suspensions of normal and leukemic human bone marrow cells were injected into lethally irradiated nude mice. As judged by splenic focus assay, cells of human bone marrow suspensions were uniformly unable to establish colonies in the spleen, although comparably treated bone marrow cells from genetically unrealted mice readily produced such colonies. It thus appears that the nude mouse is able to prevent establishment of intravenously injected human bone marrow cells by means not involving T cell-dependent immunologic discrimination.

Animals↗
PubMed1980

Immunologic mechanisms in aplastic anemia.

The existence of abnormalities of the immune system in patients with aplastic anemia is controversial. Review of the evidence for immune deficiency as a component of the aplastic process in these patients reveals generally intact lymphocyte function, but a variable degree of monocyte impairment. Evidence is presented that excessive T-lymphocyte activity may be implicated in the pathogenesis of aplastic anemia, but this complicated by the possible induction of such suppressor cells in response to blood transfusions.

Adolescent↗
PubMed1980

Hemoglobin Nigeria (alpha-81 Ser replaced by Cys):a new variant associated with alpha-thalassemia.

Hematologic evaluation of a Nigerian obstetrical patient disclosed the presence of sickle-cell trait as well as evidence of a hemoglobin alpha-chain abnormality. Hemoglobins containing the variant alpha-chain were isolated by DEAE-cellulose column chromatography, and analysis of the purified alpha-chain demonstrated a ser replaced by cys substitution at alpha-81. The abnormal alpha-chain represented approximately 45% of the total, and hemoglobins containing this alpha-chain appeared to have normal stability and functional properties. In addition to the abnormal hemoglobins that were identified in this patient, she also was found to have persistent microcytosis in the absence of iron deficiency, and the percentage of HbS in her erythrocytes was less than that usually present in individuals with sickle cell trait. These findings, together with a reduced alpha/beta globin synthesis ratio from her peripheral blood reticulocytes, indicated that the presence of alpha-thalassemia trait. Hematologic findings from members of the patients's family suggest that an alpha-thalassemia gene may be linked to that of the structurally abnormal alpha-chain.

Absorption↗