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Biomedical subjects

D Ridgway

Publications and source records attributed to D Ridgway.

36 records · Page 2Linked to original sources
PubMed1989

Attenuation of asparaginase-induced hyperglycemia after substitution of the Erwinia carotovora for the Escherichia coli enzyme preparation.

L-asparaginase, an enzyme with established antileukemic activity, increases the induction rate and duration of remission of acute lymphoblastic leukemia when added to vincristine and prednisone for induction therapy. Enzymes derived from two different bacterial sources (Escherichia coli and Erwinia carotovora) are in common use. These enzymes may be associated with toxic reactions of differing frequency and severity. Specifically, the complication of enzyme-induced hyperglycemia may be seen more frequently after exposure to the E. coli product. The authors present two patients in whom it was necessary to substitute the Erwinia enzyme for the E. coli enzyme because of the occurrence of severe allergic reactions to the E. coli enzyme. Hyperglycemia induced by the first product improved after the substitution, suggesting that the Erwinia enzyme may be less diabetogenic than the E. coli enzyme.

Adolescent↗
PubMed1989

Successful bone marrow transplantation with split lymphoid chimerism in DiGeorge syndrome.

A female infant with DiGeorge syndrome associated with severe T-cell immunodeficiency underwent a successful bone marrow transplantation from her HLA-identical, mixed leukocyte culture-nonreactive brother at 5 months of age. Mature circulating T cells and mitogen-induced proliferative responses were detectable at 10 days posttransplant, and by 8 months post-transplant functional T- and B-cell reconstitution was documented by normal responses to mitogens and normal levels of serum immunoglobulins as well as in vitro and in vivo T-cell reactivity to specific antigens and production of specific antibody to T cell-dependent antigens in vivo. Phytohemagglutinin-induced interleukin-2 production and cell surface interleukin-2 receptor expression improved posttransplant, with normal production values observed by 8 months posttransplant. Histologic examination of appendix and thoracic lymph node obtained 9 and 17 months posttransplant, respectively, revealed near-normal lymphoid architecture, with germinal center formation providing morphologic confirmation of reconstitution. Stable split lymphoid chimerism with T cells of donor origin and B cells remaining recipient in origin was documented by sex chromosome analysis. Two years posttransplant the subject remains free of serious infections. In conclusion, this case indicates that bone marrow transplantation can produce peripheral immunoreconstitution without need for significant thymic influence, most likely by providing a source of postthymic T cells, and that bone marrow transplantation should be considered a therapeutic option in patients with DiGeorge syndrome associated with severe T-cell deficiency.

Bone Marrow Transplantation↗
PubMed1989

Elevated production of interleukin-2 by lymphocytes from children with acute leukemia.

Abnormalities of the production of interleukin-2 (IL-2) may play an important role in the immunologic dysfunction observed in pediatric leukemia patients. For an evaluation of the ability of lymphocytes from leukemic children to produce this cytokine, the production of IL-2 by mitogen-stimulated peripheral blood mononuclear cells was determined in children with acute leukemia at the time of diagnosis, during clinical remission, and at the time of relapse. Of 16 patients, 11 (69%) with either acute lymphoblastic leukemia or acute nonlymphoblastic leukemia at the time of diagnosis had IL-2 production levels above the highest level observed in control subjects, and all but one had values above the control mean. Three of five treated patients had elevated IL-2 production at the time of bone marrow relapse. In addition, of 37 patients examined during clinical remission (both during chemotherapy and after the completion of maintenance chemotherapy), five had IL-2 production values above the control range and four of these five patients subsequently had relapses, compared with only one relapse in the remaining 32 patients with normal or below-normal levels of IL-2 production. These results demonstrate an increased ability to produce IL-2 by many patients with acute leukemia, both at the time of diagnosis and at relapse. Elevated IL-2 production may represent an immunologic response to leukemic cells and in some patients may provide a marker for persistent leukemia.

Adolescent↗
PubMed1988

Interleukin 1-dependent paracrine granulopoiesis in chronic granulocytic leukemia of the juvenile type.

Marrow and peripheral blood cells from nine children with juvenile chronic granulocytic leukemia (JCGL) demonstrated intense (94 +/- 16% maximum) spontaneous granulocyte/macrophage colony growth but cells from five children with the adult variety of CGL did not. This unusual pattern of colony growth depended upon a stimulatory protein(s) produced by mononuclear phagocytes. No GM-CSA activity was found in any chromatofocused fraction of JCGL monocyte-conditioned media but an activity that induced GM-CSA in umbilical vein endothelial cells was detected at pI 6.9-7.2. Moreover, the CSA-inducing monokine was neutralized by an anti-IL-1 antibody in vitro and, in the one case so tested, the same antibody also inhibited "spontaneous" colony growth. Therefore granulocyte/macrophage colony growth in JCGL is characteristically abnormal and distinguishes JCGL from the adult form of the disease. This abnormality depends upon the production, by mononuclear phagocytes, of IL-1 which, in turn, stimulates the release of high levels of colony stimulating activity by other cells. The high proliferative activity of CFU-GM we found in JCGL patients, and the high levels of GM-CSA found in their serum are compatible with the view that the in vitro abnormality reflects a similar abnormality in vivo.

Adult↗
PubMed1988

Granulocyte macrophage colony-stimulating activity production by cultured human thymic nonlymphoid cells is regulated by endogenous interleukin-1.

Supernatants of cultured human thymic nonlymphoid cells were assayed for granulopoietic factors using cultures of low density bone marrow mononuclear cells (LD-BMMC). Thymic nonlymphoid cell-conditioned medium (TNLC-CM) supported vigorous myeloid colony growth of LD-BMMC, and of LD-BMMC depleted of T lymphocytes and/or monocytes. Colony stimulating activity (CSA) in TNLC-CM was abrogated by a highly specific neutralizing antiserum against recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF). TNLC-CM also enhanced colony growth in LD-BMMC stimulated by colony stimulating activity from a giant cell tumor culture (GCT). The enhancing activity of TNLC-CM, unlike its CSA activity, required the presence of adherent cells in the marrow cell culture. The addition of anti-interleukin-1 (anti-IL-1) antibody to TNLC-CM inhibited the GCT-enhancing activity, but not the CSA. When the anti-IL-1 immunoglobulin was added directly to cultures of thymic nonlymphoid cells, GM-CSF production was completely inhibited, and the GCT enhancing activity was neutralized. We conclude that an intercellular regulatory network exists in cultured thymic explants in which GM-CSF expression is induced by IL-1. In this system, the granulopoietic effect of IL-1 derives not from a direct effect on myeloid progenitors, but from its ability to recruit CSA production by other cells.

Antibodies, Monoclonal↗
PubMed1987

Unsuspected non-Hodgkin's lymphoma of the tonsils and adenoids in children.

Six children with lymphoreticular malignancy arising in the pharyngeal tonsils or adenoids are presented. Early clues to the possible malignant nature of the enlargement of tonsils and adenoids in this series include: asymmetric and persistent enlargement, the absence of such manifestations of infection as fever or pain, and the association of atypical adenopathy. Lack of clinical suspicion brings with it the risk of delayed diagnosis and possible compromise of optimal therapy.

Adenoidectomy↗
PubMed1986

Enhanced lymphocyte response to PHA among leukemia patients taking oral lithium carbonate.

Seven children receiving maintenance therapy for acute lymphoblastic leukemia (in remission) were given oral lithium carbonate for 12 weeks. Hematologic values, serum immunoglobulin levels, and responsiveness of peripheral blood mononuclear cells to mitogen stimulation were studied during the lithium treatment period, and compared to measurements made during a 12-week period when no lithium was administered (children served as their own controls). Changes attributable to treatment with lithium carbonate included increases in total white blood cell count, circulating neutrophil count, and response to phytohemagglutinin-P. No important toxicity to lithium carbonate was observed.

Adjuvants, Immunologic↗
PubMed1986

Expression of normal myeloid-associated antigens by acute leukemia cells.

Monoclonal antibodies that react with hematopoietic cells and their precursors in a stage and lineage restricted fashion were used in indirect immunofluorescence assays to examine leukemic cells from 105 pediatric age patients. The differentiative states of blasts from 42 patients with acute nonlymphocytic leukemia (ANLL) were defined by these antibodies. When these were compared to their morphologic and histochemical levels of differentiation as defined by the French-American-British (FAB) classification, no direct relationship was found. The reactivity of these antibodies with leukemic cells from 63 patients with acute lymphocytic leukemiA (ALL) was also investigated, and the usefulness of these antibodies in distinguishing leukemias of myeloid from those of lymphoid origin was demonstrated.

Acute Disease↗
PubMed1985

The effects of thymic epithelial monolayer-conditioned medium on suppressor cell function following chemotherapy in pediatric patients.

Human thymic epithelial monolayer-conditioned medium (TEM-CM) enhanced concanavalin A (ConA)-induced suppressor T-lymphocyte activity in 15 of 17 studies of fractionated light-density bone marrow mononuclear cells (LD-BMMC) obtained from pediatric cancer patients within 7 days of chemotherapy (P less than 0.001). However, TEM-CM depressed ConA-induced suppressor T-lymphocyte activity in 14 of 18 studies of LD-BMMC obtained from patients who had received their chemotherapy 14-21 days previously (P less than 0.05). In studies of LD-BMMC from normal subjects, TEM-CM did not show any significant effect on suppressor cell activity, nor did TEM-CM significantly affect spontaneous suppressor cell activity in patients or normals. The effect of direct culture on thymic epithelial monolayers was equivalent to the effect of TEM-CM in both ConA-induced and spontaneous suppressor cell assays. These data demonstrate thymic factor-mediated changes in suppressor T-cell activity of pediatric cancer patients and suggest a postchemotherapy alteration in the bone marrow population of inducible prethymic T cells.

Adolescent↗
PubMed1985

Immunodiagnosis of childhood ALL with monoclonal antibodies to myeloid and lymphoid associated antigens.

Sixty-five cryopreserved leukemic samples from children diagnosed and treated as having acute lymphocytic leukemia (ALL) were retrospectively examined for the presence of lymphoid and myeloid associated antigens by indirect immunofluorescence using monoclonal antibodies. Expectedly, the majority of these specimens expressed antigens known to be expressed on lymphoid, and not myeloid malignancies. These included the common acute lymphoblastic leukemia antigen (CALLA), the p32 B-cell associated antigen, and T-cell associated antigens. Leukemic cells from the 8 remaining patients expressed antigens known to be present on both myeloid and lymphoid leukemias. These included HLA/DR, and the antigens identified by BA-1 and BA-2. Cells from 2 of these 8 patients reacted with antibodies that define antigens present on normal and malignant myeloid cells. Both specimens reacted with 1G10, an anti-granulocyte antibody, and one reacted with 5F1 which reacts with monocytes, nucleated red blood cells, megakaryocytes and platelets. One of these patients relapsed while receiving ALL therapy, and the morphology of her leukemic cells became characteristic of acute monocytic leukemia (AMoL). The second patient failed ALL therapy but responded to standard acute nonlymphocytic leukemia (ANLL) therapy, clearing her peripheral blasts. Thus these studies confirm that cell surface phenotyping with monoclonal antibodies can recognize ALL cells that express myeloid rather than lymphoid associated antigens and demonstrate that the malignant cells display a clinical behavior consistent with the diagnosis of ANLL.

Adolescent↗
PubMed1980

Vincristine in the etiology of toxicity of high-dose methotrexate therapy.

A 14-year-old received a six-hour infusion of methotrexate (71/2 g/M2) with vincristine (2 mg) and citrovorum rescue according to a standard protocol for adjunctive chemotherapy of osteogenic sarcoma. Signs of mild vincristine toxicity occurred from 2-5 days following the infusion; these including jaw pain, decreases in deep tendon reflexes, and a transient ileus. Clearance of serum methotrexate was delayed during the period of ileus and severe methotrexate toxicity was observed.

Adolescent↗
PubMedDate not supplied

Increased heterologous protein production in Aspergillus niger fermentation through extracellular proteases inhibition by pelleted growth.

The dependence of filamentous fungal protease secretion on morphology was investigated by employing the recombinant Aspergillus niger strain AB4.1[pgpdAGLAGFP] which contains a gene for the glucoamylase-GFP (green fluorescence protein) fusion protein. Different inoculum levels were used to obtain different sizes of pellet or free mycelia. The extracellular protease activity of the cultures varied with the pellet size and decreased dramatically when the morphology was changed from free mycelia to pellets. The culture with an optimal pellet size of 1.6 mm was obtained from an inoculum of 4 x 10(6) spores/mL. It resulted in a specific protease activity of 158 units/L, only one-third of that in free mycelial growth, and a maximum specific GFP yield of 0.98 mg/g (cell mass) compared to 0. 29 mg/g for free mycelial growth with an inoculum of 10(7) spores/mL. The results indicate that this bioprocessing strategy can be effectively used to inhibit protease activity in filamentous fungal fermentation and thereby to enhance heterologous protein production.

Aspergillus niger↗
PubMedDate not supplied

Stable production of a human growth hormone antagonist from CHO cells adapted to serum-free suspension culture.

Human growth hormone (hGH) is a polypeptide with 191 amino acids and a molecular mass of 22 kDa. An hGH analogue was created with a single amino acid substitution (glycine[G] 120 to arginine[R]) in the third alpha-helix of the hGH molecule. This hGH analogue, named hGHG120R, was found to be an hGH antagonist. It is a parenteral drug candidate for treating conditions in which hGH levels are abnormally high, as found in type I diabetics. Previously, a genetically engineered anchorage-dependent mouse L cell line was created that produced and secreted hGHG120R in culture media (Dulbecco's modified Eagle's medium, DMEM) supplemented with 5% NuSerum IV. A multistep downstream process was developed to purify hGHG120R. The process consisted of cell clarification, salt precipitation, membrane ultrafiltration, size exclusion chromatography, reversed phase high-performance liquid chromatography, phase separation, and lyophilization. Here, we present the development of a superior eukaryotic system using a proper combination of genetic elements, cell line, and media formulation. This system is suitable for the large-scale production of the recombinant protein and is superior to the previously developed system in that it increases the specific production rate and at the same time eases the burden of the purification process, in both time and efficiency. Dihydrofolate reductase mutant (DHFR-) Chinese hamster ovary (CHO) cells were used that were stably transfected with an expression vector in which the hGHG120R gene is driven by the relatively strong human cytomegalovirus-early gene regulatory region. The hGHG120R tested to be biologically active. These cells were then adapted to grow in suspension in CHO-S-SFM (serum-free media). High cell densities, typically 2.0 x 10(6) cells/mL were obtained from spinner flask cultures. Partial purification of hGHG120R from CHO cell cultured media revealed that the level of impurities in SFM was significantly lower than the serum-supplemented DMEM. This suggests that the salt precipitation and the SEC step need not be employed in the purification of hGHG120R from SFM. This would result in a reduction of the operating time by 50 h and boost the recovery yield of hGHG120R to 75%.

Adaptation, Physiological↗
PubMedDate not supplied

Primary endoluminal stenting of transplant renal artery stenosis from cadaver and non-heart-beating donor kidneys.

This study evaluated the efficacy of primary endovascular stenting in cases of transplant renal artery stenosis (TRAS) from cadaver and non-heart-beating donor kidneys. Patients with TRAS (n = 13) from a single-centre transplant population (n = 476) were treated by primary percutaneous angioplasty and endovascular stenting. The short-term efficacy of this intervention is demonstrated in terms of serum creatinine, glomerular filtration rate (GFR) biochemical, anti-hypertensive medications and mean arterial blood pressure control. Stenting for TRAS was performed in male (n = 10) and female (n = 3) recipients. The median age at transplantation was 55 yr (range 10-67 yr). Stenting occurred at a median duration of 410 d post-transplantation (range 84-5799 d). Mean serum creatinine (pre, 247 micromol/L; post, 214 micromol/L; p = 0.002), GFR (pre, 82.6 mL/min; post, 100.9 mL/min; p < 0.001), arterial blood pressure (pre, 104 mmHg; post, 97 mmHg; p = 0.036) and the number of anti-hypertensive medications required (pre, 3.4; post, 3.0; p = 0.002) showed significant improvement after post-endovascular therapy. There were no serious complications encountered. Primary endovascular stenting of TRAS produces a significant improvement in biochemical parameters of renal graft function and in blood pressure stability, with the benefit of low patient morbidity and single arterial puncture. Primary endoluminal stenting of TRAS is a safe and effective procedure for the treatment of TRAS.

Adolescent↗