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Biomedical subjects

G Thurman

Publications and source records attributed to G Thurman.

10 recordsLinked to original sources
PubMed2000

Human neutrophil immunodeficiency syndrome is associated with an inhibitory Rac2 mutation.

A 5-week-old male infant presented with severe bacterial infections and poor wound healing, suggesting a neutrophil defect. Neutrophils from this patient exhibited decreased chemotaxis, polarization, azurophilic granule secretion, and superoxide anion (O(2)(-)) production but had normal expression and up-regulation of CD11b. Rac2, which constitutes >96% of the Rac in neutrophils, is a member of the Rho family of GTPases that regulates the actin cytoskeleton and O(2)(-) production. Western blot analysis of lysates from patient neutrophils demonstrated decreased levels of Rac2 protein. Addition of recombinant Rac to extracts of the patient neutrophils reconstituted O(2)(-) production in an in vitro assay system. Molecular analysis identified a point mutation in one allele of the Rac2 gene resulting in the substitution of Asp57 by an Asn (Rac2(D57N)). Asp57 is invariant in all defined GTP-binding proteins. Rac2(D57N) binds GDP but not GTP and inhibits oxidase activation and O(2)(-) production in vitro. These data represent the description of an inhibitory mutation in a member of the Rho family of GTPases associated with a human immunodeficiency syndrome.

Antigens, CD↗
PubMed2000

Functional characteristics of neutrophils collected and stored after administration of G-CSF.

BACKGROUND: Granulocyte transfusion may be used in neutropenic patients with severe bacterial or fungal infections that are unresponsive to antibiotic therapy. However, the inability to store granulocyte concentrates limits their clinical usefulness. STUDY DESIGN AND METHODS: Neutrophil chemotaxis and NADPH oxidase activity and the integrity of the neutrophil NADPH oxidase system were examined after apheresis collection and during storage to 48 hours. Neutrophils were mobilized in vivo by G-CSF, collected by apheresis techniques, and stored in apheresis bags in the presence and absence of additional G-CSF. For all experiments, cells were further purified by standard techniques of dextran sedimentation and hypotonic RBC lysis. RESULTS: Neutrophil chemotaxis was preserved to 24 hours of storage but was not affected by the G-CSF added to storage units. The NADPH oxidase system was also preserved as a functioning complex, and both cytosolic proteins and membrane-associated proteins were normal to 48 hours. However, there were divergent responses by intact cells to activating stimuli and reduced oxidase activity in the cell-free system. G-CSF did not appear to significantly affect NADPH oxidase activity or NADPH oxidase system integrity during storage. CONCLUSION: Neutrophils collected after the administration of G-CSF retained functional and biochemical characteristics for at least 24 hours of storage, which suggests additional effects of G-CSF mobilization beyond enhancing PMN yields and the possibility of storage of these components after collection.

Adult↗
PubMed1998

In vivo treatment with granulocyte colony-stimulating factor results in divergent effects on neutrophil functions measured in vitro.

We have studied the effects of granulocyte colony-stimulating factor (G-CSF) administration to normal individuals on a variety of functional and biochemical neutrophil characteristics that relate to host defense. G-CSF adversely affected neutrophil (polymorphonuclear leukocyte [PMN]) chemotaxis. While this could be partially explained by reduced assembly of neutrophil F-actin, we also recognized an elevated cytosolic calcium mobilization and a normal upregulation of neutrophil CD11b. G-CSF resulted in reduced PMN killing of Staphylococcus aureus with a 10:1 (bacteria:neutrophil) ratio and normal killing with a 1:1 ratio. In association with this, we demonstrated divergent effects on the respiratory burst of intact cells and divergent effects on the content of marker proteins for neutrophil granules. While G-CSF may have resulted in increased content of cytochrome b558 in the cell membrane, it did not alter the amounts of cytosolic oxidase components. After therapy, there was normal content of the azurophilic granule marker, myeloperoxidase, decreased content of the specific granule marker, lactoferrin, and normal content of lysozyme (found in both granules classes). Finally, G-CSF therapy markedly reduced the apoptotic rate of the isolated neutrophil. Therefore, considering disparate functional and biochemical activities, the real benefit of G-CSF therapy may lie in enhanced number and survival of neutrophils.

Adult↗
PubMed1998

The effects of stem cell factor and granulocyte colony stimulating factor therapy on the activity of the neutrophil NADPH oxidase enzyme system.

BACKGROUND: To explore the effect of cytokine therapy on the NADPH oxidase in mature myeloid cells, we isolated neutrophils from patients receiving recombinant human granulocyte colony stimulating factor (G-CSF) and recombinant human stem cell factor (SCF) and evaluated oxidase activity. All patients had relapsed neoplastic disease and were at least 3 three weeks since the last course of chemotherapy or cytokine therapy. METHODS: Stimulus induced superoxide anion (O2-) production in response to PMA (200 ng/mL), fMLP (1 mumol/L), platelet activating factor (PAF, 2 mumol/L) priming of the fMLP induced response, and opsonized zymosan OZ (1 mg/mL) was measured. Polymorphonuclear leukocyte (PMN) subcellular components were prepared, after nitrogen cavitation, by separation on discontinuous sucrose gradients and NADPH oxidase activity was assessed in a SDS cell-free system. RESULTS: SCF had no effect on the activity of the neutrophil oxidase. Neutrophils isolated from patients treated with G-CSF and stimulated with PMA produced less (superoxide anion) O2- after therapy. PAF priming of the fMLP induced respiratory burst was also reduced after therapy with G-CSF. Subcellular NADPH oxidase activity was reduced before cytokine therapy commenced. This activity did not improve with cytokine treatment. CONCLUSIONS: It appears likely from this study that G-CSF therapy, with or without SCF, does not cause significant enhancement of neutrophil NADPH oxidase activity.

Adult↗
PubMed1997

Mammal toxicity assessment of the plant molluscicide, Apodytes dimidiata (Icacinaceae), in South Africa.

Apodytes dimidiata has recently come to the fore as a potential plant molluscicide for schistosomiasis control in rural communities in South Africa. Prior to field applications of its leaves and extract to waterbodies, selected acute and sub-acute mammal toxicity tests were conducted in accordance with the Organisation of Economic Cooperation and Development (OECD) Guidelines to identify any potential hazards that might arise form the plant's use. Acute and sub-acute mammal toxicity test results classified A. dimidiata as non-toxic and non-irritating. Based on this toxicity evaluation, the dried leaf material and aqueous extracts of this plant are considered safe for use in preliminary field trials.

Animals↗
PubMed1990

Electron spin echo envelope modulation evidence for carbonate binding to iron(III) and copper(II) transferrin and lactoferrin.

Iron binding to transferrin and lactoferrin requires a synergistic anion, which is carbonate in vivo. The anion is thought to play a key role in iron binding and release. To understand better the iron-carbonate interaction, experiments were performed with iron(III) and copper(II) complexes of human milk lactoferrin and serum transferrin with carbon-13-labeled carbonate. Modulation frequencies were present in the Fourier transforms of two-pulse and three-pulse electron spin echo envelope modulation data for the Fe(III) and Cu(II) complexes, consistent with binding of carbonate to both metals. The metal-13C interaction was similar for the lactoferrin and transferrin complexes. Spin coupling to the nitrogen of a coordinated histidine imidazole was observed for both metals. Both the metal-nitrogen and the metal-carbon spin coupling constants were about a factor of 5 smaller for the iron complexes than for the copper complexes, which indicated substantial similarity in the metal-carbonate and metal-imidazole binding for the two metals.

Carbonates↗
PubMed1989

Comparison of the electron spin echo envelope modulation (ESEEM) for human lactoferrin and transferrin complexes of copper(II) and vanadyl ion.

Copper(II) and vanadyl ions were bound to human milk lactoferrin or serum transferrin with carbonate or oxalate as the synergistic anion. Electron spin echo envelope modulation (ESEEM) due to nitrogen of a coordinated histidine imidazole was observed for both the copper and vanadyl complexes. For both metals, the modulation frequencies in the Fourier transforms of the data were similar for the two proteins and were weakly dependent on anion. When data in D2O/glycerol-d3 were compared with data in H2O/glycerol, the deep deuterium modulation indicated multiple exchangeable protons in the vicinity of the metals with at most one proton within about 2.9 A of the metal. The distribution of exchangeable protons around the metals as probed by ESEEM was the same, within experimental uncertainty, for the copper or vanadyl complexes with either carbonate or oxalate as the anion. When 13C-labeled oxalate was used as the synergistic anion, 13C-ESEEM was observed for both the copper and vanadyl complexes of lactoferrin and transferrin. The deeper 13C modulation for copper and vanadyl transferrin [13C]oxalate than for vanadyl transferrin [13C]carbonate suggests that both ends of the oxalate are bound to the metal in the transferrin and lactoferrin complexes.

Copper↗
PubMed1983

A system for obtaining large numbers of cryopreserved human monocytes purified by leukapheresis and counter-current centrifugation elutriation (CCE).

A system has been developed for the isolation of large numbers of unfractionated mononuclear cells from single, well characterized normal individuals and for the separation by elutriation of these cells into populations of greater than 90% pure monocytes and greater than 99% pure lymphocytes. The total number of monocytes obtained from a single donor averaged about 550 million. After cryopreservation and thawing of these cells, the viability remained greater than 90%, 80% of original cells were recovered, and the ability to ingest antibody-coated targets was comparable to that of fresh monocytes. The cells remained sterile without the use of antibiotics and were suitable for long-term culture. The monocytes that were isolated and cryopreserved by these procedures functioned reproducibly as inhibitors of tumor cell growth and in an assay of responsiveness to monocyte migration inhibitory factor (MIF).

Blood Preservation↗