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J Tong

Publications and source records attributed to J Tong.

At least 91 records · Page 5Linked to original sources
PubMed1995

[3 retinoic acid isomers on proliferation and differentiation properties of APL cell line-NB4].

We examined the effect of three RA isomers, including ATRA, 13C-RA and 9C-RA, on the proliferation and differentiation properties of NB4 cells, a cell line established from APL patient and carrying the typical translocation t (15;17). Standard parameters such as cell morphology, cell growth curve, dynamics of cell cycle, expression of clusters of differentiation and reduction of nitro blue tetrazolium (NBT) were used to evaluate the effects of the three isomers. During the first 48 hours of RA treatment, the APL cell maturation was coupled with the cell proliferation. Moreover, significant differences of differentiation-induced effect among RA isomers were observed. ATRA showed better results than 13C-RA while 9C-RA functioned even better than ATRA. These data are helpful to understand the mechanisms, by which RAs induce promyelocytic leukemia cell differentiation and open a new prospect for the clinical use of novel retinoic acid isomers.

Cell Division↗
PubMed1995

Sustained vasoconstriction associated with daily cyclosporine dose in heart and lung transplant recipients: potential pathophysiologic role of endothelin.

Transient decreases in glomerular filtration rate (GFR) and renal plasma flow (RPF) have been associated with each daily dose of cyclosporine (CYA) in patients with renal allografts. We examined the differential dose effects of CYA on native renal function in 24 recipients of heart or lung transplants (treated with 7.3 +/- 0.5 mg/kg/day [mean +/- SEM]) and in seven patients with psoriasis (treated with 4.2 +/- 0.7 mg/kg/day). GFR and RPF were measured by urinary inulin and para-aminohippuric acid clearances 2 hours before the morning CYA dose and for 6 hours after. The age of heart and lung transplant recipients at renal study (2 months after transplantation) was 47 +/- 2.0 years. Their serum creatinine levels rose from 80 +/- 4.0 mumol/L during the first week after transplantation to 120 +/- 4.0 mumol/L at renal study (p < 0.0001). Their GFR and RPF were decreased before the CYA dose at 64 +/- 2.4 and 340 +/- 16 ml/min per 1.73 m2 and did not vary during the study. In comparison, the age of patients with psoriasis was 51 +/- 4.6 years at renal study (24 +/- 4.0 months after CYA treatment). Their serum creatinine levels rose from 80 +/- 4.0 mumol/L before treatment to 100 +/- 10 mumol/L at renal study (p = 0.07). Transient decreases of their baseline GFR and RPF (85 +/- 7.4 and 380 ml/min per 1.73 m2) with a nadir occurring during the first 2 hours of CYA ingestion were observed together with the recovery of these parameters toward baseline by the end of the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclosporine↗
PubMed1995

Cloning and functional characterization of the chicken c-ros promoter.

Our previous study has shown that chicken c-ros is specifically expressed in certain epithelial cells of kidney, intestine, lung, bursa, thymus, and testis, and the expression is regulated temporally and spatially. To explore the molecular basis for the regulation of c-ros expression, we have cloned and characterized the chicken c-ros promoter. The most 5' c-ros cDNA was isolated and sequenced. Using the 5' cDNA as a probe, three genomic DNA clones containing the 5' c-ros cDNA sequence were isolated. Primer extension and RNase protection analysis were used to map the transcription initiation site for the c-ros mRNA in kidney and intestine. The sequence of the 1.3-kb region upstream of the initiation site contains TATA and CAAT boxes at 26 and 54 nucleotides, respectively, upstream of the initiation site. In addition, transcription factor binding sites for AP1, AP2, and Oct1 and several direct and inverted repeats are present within 1 kb upstream of the initiation site. The 1.3-kb DNA, when placed upstream of the chloramphenicol acetyltransferase gene, was shown to be functionally active. Serial deletions of this putative c-ros promoter allowed us to define a minimum c-ros promoter and to identify positive and negative regulatory regions. Using two oligonucleotides corresponding to a positive regulatory and potential factor binding region, we have demonstrated, by gel mobility shift experiments, their specific binding to nuclear extracts from kidney, intestine, and thymus. The binding pattern corresponds to the tissue specificity and temporal control of c-ros mRNA expression.

Animals↗
PubMed1994

Cloning, sequencing, and expression of RecA proteins from three distantly related thermophilic eubacteria.

Sequences of the recA genes of the highly divergent thermopholic eubacteria Thermus aquaticus (and Thermus thermophilus), Thermotoga maritima, and Aquifex pyrophilus were determined from fragments derived by polymerase chain reaction (PCR) with degenerate primers and from inverse PCR products obtained using unique primers based on the fragment sequences. The source of the PCR products was verified by Southern hybridization. Complete PCR-derived recA genes were cloned into an expression vector regulated by a temperature-sensitive lambda-repressor, and independently derived clones expressing thermostable recA were selected. DNA sequences were verified to be authentic by direct cycle-sequencing of PCR products and/or sequencing of several clones. In contrast to Escherichia coli RecA protein, all the purified thermophilic RecA proteins exhibited single-stranded DNA-dependent ATPase activity optima above 70 degrees C. Phylogenetic analysis of RecA sequences suggested that the thermophilic RecA proteins were at least as different from one another as were Gram-positive organisms, mesophilic Gram-negative organisms, and cyanobacteria. In spite of substantial sequence divergence, interesting characteristics of the thermostable RecA proteins included increased valine content, common amino acid replacements at two highly conserved sites, and an increase in the calculated isoelectric point of approximately a full pH unit.

Adenosine Triphosphate↗
PubMed1994

Direct square-wave voltammetry of superoxidized [4Fe-4S]3+ aconitase and associated 3Fe/4Fe cluster interconversions.

We report a direct square-wave voltammetric study of the iron-sulfur enzyme, aconitase, at the pyrolytic graphite edge electrode. New and established redox driven reactions were observed and the equilibrium reduction potential for each couple was determined: E0'[3Fe-4S]1+/0 = -268 mV, E0'[4Fe-4S]2+/1+ = -450 mV, E0'[4Fe-4S]3+/2+ = +100 mV, E0'Linear Form = -281 mV, and putatively, E0'[3Fe-4S]0/2- congruent to -1000 mV, all versus normal hydrogen electrode. Most importantly we have directly observed the superoxidized [4Fe-4S]3+ form of aconitase (originally proposed by Emptage, M. H., Dreyer, J.-L., Kennedy, M. C., and Beinert, H. (1983) J. Biol. Chem. 258, 11106-11111) and directly followed its conversion to the [3Fe-4S]1+ form; this intermediate is required for the deactivation of aconitase. Without exogenous ferrous iron, [3Fe-4S]0 aconitase is apparently super-reduced at very negative potentials to the [3Fe-4S]2- form and the concomitant formation of [4Fe-4S]2+ aconitase was followed over time. It is the apparent decomposition of super-reduced [3Fe-4S]2- aconitase that provides the source of ferrous iron for the interconversion of [3Fe-4S]0 aconitase to the [4Fe-4S]2+ form. Voltammetry of free and substrate bound [4Fe-4S]2+ aconitase showed that the latter is less susceptible to oxidation but, surprisingly, has the same E0'[4Fe-4S]3+/2+.

Aconitate Hydratase↗
PubMed1994

Enhanced cancer growth in mice administered daily human-equivalent doses of some H1-antihistamines: predictive in vitro correlates.

BACKGROUND: Present studies of drug-induced tumor growth promotion have evolved from earlier investigations into the mechanism of action of N,N-diethyl-2-[4-(phenylmethyl)phenoxy[ethanamine.HCl, a tamoxifen derivative which potently inhibits lymphocyte mitogenesis in vitro and stimulates tumor growth in vivo. It is thought that potency to bind to intracellular histamine receptors (HIC), some of which are on cytochromes P450, may correlate with tumor growth-promoting activity. PURPOSE: We assessed the effectiveness of five in vitro assays in predicting in vivo tumor growth stimulation by the H1-antihistamines loratadine, astemizole, cetirizine, hydroxyzine, and doxylamine. METHODS: Potency of each agent was ranked 1-5 in each of the following in vitro assays: 1) inhibition of [3H]histamine binding to microsomal HIC, 2) inhibition of histamine binding to microsomal P450, 3) inhibition of the P450-catalyzed demethylation of aminopyrine, 4) inhibition of lymphocyte mitogenesis, and 5) stimulation of tumor colony formation. An overall rank score was assigned to each drug and correlated with tumor growth stimulation in vivo. Two laboratories conducted in vivo studies in a blinded fashion. Female C57BL and C3H mice were given a subcutaneous injection on day 1 of syngeneic B16F10 melanoma cells (5 x 10(5)) or C-3 fibrosarcoma cells (1 x 10(5)), respectively. Mice were randomly assigned to treatment groups, then received a single, daily intraperitoneal injection of an estimated human-equivalent dose (or range of doses) of antihistamine or vehicle control for 18-21 days before being killed. Tumors were surgically removed and wet weights compared statistically among groups. RESULTS: The cumulative potency of each drug in affecting tumor growth or growth mechanisms in the five in vitro assays ranked as follows: Loratidine and astemizole ranked highest and were equally potent, followed in decreasing order by hydroxyzine, doxylamine, and cetirizine. A significant correlation (r = .97; P < .02) was observed between the rank order of potency of the antihistamines in all five in vitro assays and the rank order to enhance tumor growth in vivo: Loratidine and astemizole significantly (P < .001) promoted the growth of both melanoma and fibrosarcoma, hydroxyzine significantly (P < .001) promoted the growth of melanoma, while doxylamine and cetirizine did not promote the growth of either tumor. CONCLUSION: Data demonstrate that the in vitro assays predicted the propensity of each H1-antihistamine to stimulate cancer growth in vivo. IMPLICATION: These in vitro tests may prove valuable to screen potential tumor growth promoters.

Animals↗
PubMed1994

A hydrodynamic interpretation of crisis in sickle cell anemia.

The occurrence of crisis events in patients with sickle cell disease is associated with an increase in blood plasma viscosity, the hydrodynamic consequences of which are examined here. A mathematical model of the flow of sickle cells in capillaries predicts that for moderate increases in plasma viscosity, a regime of multivalued solutions for blood velocities is encountered, and the likely physical response is a precipitous drop to the lowest velocity solution. This behavior results from the coupling of the hydrodynamics with sickle erythrocyte rheology and oxygen transport to the surrounding tissue; no such catastrophe is predicted for normal erythrocytes. The type of velocity changes predicted by the model strongly suggest that plasma viscosity changes may play an important role in initiating or exacerbating crisis.

Anemia, Sickle Cell↗
PubMed1994

In vitro study of osteoblastic cells from patients with idiopathic osteoporosis and comparison with cells from non-osteoporotic controls.

We have examined bone cells derived from iliac crest trabecular explants of 30 patients with idiopathic osteoporosis and 45 control subjects in order to determine whether intrinsic abnormalities in osteoblast function may contribute to the decreased bone formation observed in this disease. Bone cells isolated from all subjects expressed several in vitro characteristics of the osteoblast phenotype including adenylate cyclase responsiveness to parathyroid hormone (PTH) and prostaglandin E1 (PGE1), basal and 1,25(OH)2D3-stimulated alkaline phosphatase activity and osteocalcin production. Results were compared amongst three subject groups; young controls less than 40 years old, older controls over 40 years old, and osteoporotics. Osteoporotic cells were found in general to be fully active in vitro. There were no differences between osteoporotic and control cells in their basal levels of adenylate cyclase, or alkaline phosphatase, in their growth rates, or cell morphology. The cyclic AMP (cAMP) response to PTH was significantly lower in osteoporotic cells (71%, p < 0.01) and older control cells (64%, p < 0.005) relative to the response in cells from younger controls, suggesting that the decreased responsiveness in osteoporotic cells was due to subject age rather than the osteoporotic state. At the same time, the cAMP responses to PGE1 and cholera toxin were similar in cells from all three subject groups. The response to forskolin was reduced to about 40% in osteoporotic cells compared with controls, but this was not mirrored by similar differences in the responses to PTH, PGE1 or cholera toxin, suggesting that the availability of catalytic subunits is not rate-limiting in these cells. 1,25(OH)2D3-stimulated osteocalcin production was 220% higher in osteoporotics than in older controls, but the numbers tested were small and the difference did not reach significance. The one significant abnormality we observed in osteoporotic cells was in alkaline phosphatase activity: 1,25(OH)2D3-stimulated alkaline phosphatase activity was twofold higher in osteoporotics than in younger (p < 0.05), older (p < 0.05) and pooled controls (p < 0.025). The significance of this finding is unknown, but we postulate that it may reflect an intrinsic abnormality in osteoblast function in patients with idiopathic osteoporosis.

Adolescent↗
PubMed1994

The ability of diphenylpiperazines to prevent neuronal death in dorsal root ganglion neurons in vitro after nerve growth factor deprivation and in vivo after axotomy.

The mechanism of neuroprotection by the calcium channel antagonist flunarizine against neuronal death is unknown. We investigated the ability of other calcium channel antagonists (cinnarizine, nimodipine, nicardipine, diltiazem, and verapamil), calmodulin antagonists, and calpain inhibitors to prevent neuronal death in rat dorsal root ganglion neurons in vitro after nerve growth factor (NGF) deprivation and the ability of cinnarizine and diltiazem to protect in vivo after axotomy. In vitro, only neurons treated with cinnarizine or flunarizine were protected from death after withdrawal. In vivo, cinnarizine, but not diltiazem, protected dorsal root ganglion neurons in rats after unilateral sciatic nerve crush. Intracellular calcium concentration ([Ca2+]i) was evaluated with fura 2 after NGF deprivation in vitro. Neurons "committed to die" 24 h after NGF deprivation displayed a decline in [Ca2+]i before visible morphological deterioration consistent with cell death. The influx of extracellular calcium was not necessary to produce neuronal death. Neurons deprived of NGF gradually lost the ability to respond to elevated external potassium with an increase in [Ca2+]i during the first 24 h after trophic factor deprivation. After 24 h, neurons deprived of NGF could not be rescued by readministration of NGF. Neurons protected from cell death with diphenylpiperazines maintained their response to high external potassium, suggesting continued membrane integrity. We speculate that diphenylpiperazines may protect sensory neurons via an unknown mechanism that stabilizes cell membranes.

Animals↗
PubMed1994

Primitive hematopoietic progenitor cells are present in peripheral blood autografts.

In this report we have used an in vitro assay for long-term culture-initiating cells (LTC-IC) to detect primitive hematopoietic progenitor cells (HPC) in the peripheral blood (PB) of cancer patients who received high-dose cyclophosphamide (HD-CTX) followed by a combination of recombinant hematopoietic growth factors (C-HGF) including either interleukin-3 (IL-3) + granulocyte colony-stimulating factor (G-CSF), IL-3 + granulocyte-macrophage colony-stimulating factor (GM-CSF) or IL-3/GM-CSF fusion protein (PIXY-321). In addition, we have developed a quantitative assay for cells capable of generating additional colony-forming cells (pre-CFC) as a means of determining primitive HPC present in mobilized PB cells. CD34+ human leukocyte A (HLA)-DR- cells isolated from the mobilized PB were capable of initiating long-term hematopoiesis in vitro that persisted for 10 weeks, while CD34+ HLA-DR- cells obtained from the nonmobilized PB or BM were capable of sustaining long-term hematopoiesis in vitro for only 4 weeks and 8 weeks, respectively. As determined by a limiting dilution analysis of mobilized PB CD34+ HLA-DR- cells, the frequency of pre-CFC was 4.3% (range, 1.0-8.3%). Pre-CFC comprised 0.01% (range, 0.001-0.02%) of mobilized PB mononuclear cells, and 151 pre-CFC were calculated to be present in one milliliter of mobilized PB (range, 20-310/ml). These results suggest that PB mononuclear cells collected by leukapheresis following mobilization with HD-CTX + C-HGFs contain not only differentiated HPCs but also more primitive HPC.

Antigens, CD↗
PubMed1994

Further study on the spontaneous partial folding of chicken heart apocytochrome c.

It has been previously reported (Biochem. Mol. Biol. Int., 30(5), 867-876, 1993) that chicken heart apocytochrome c has stronger tendency to fold spontaneously in aqueous solution than those from other species, and the relevance of its folding state with its ability to penetrate across the lipid bilayers has also been studied. In the present paper, the spontaneous folding characteristics of chicken heart apocytochrome c was further examined by the studies of Fourier-transform infrared spectra, the properties of intrinsic tryptophan fluorescence, and the measurements of hydrophobicity. In addition, it was also demonstrated that the partially-folded apocytochrome c is easily to be aggregated and hence relatively incompetent for translocation across the phospholipid bilayers.

Animals↗
PubMed1994

Characterization and quantitation of primitive hematopoietic progenitor cells present in peripheral blood autografts.

In this report, we assess the content of primitive hematopoietic progenitor cells (HPC) that circulate transiently in the peripheral blood (PB) of cancer patients (group A) who received a PB stem-cell-mobilizing regimen that included high-dose chemotherapy (HD-CTX) of 7 g/m2 cyclophosphamide followed by a combination of recombinant hematopoietic growth factors (C-HGF), including either interleukin-3 (IL-3) plus granulocyte-colony stimulating factor (G-CSF), IL-3 plus granulocyte-macrophage colony-stimulating factor (GM-CSF), or a recombinant GM-CSF/IL-3 fusion protein (PIXY-321). These data were compared to the HPC content of PB obtained from a similar group of cancer patients that had not received such a mobilization regimen (group B). Monoclonal antibody staining and fluorescence-activated cell sorting (FACS) were used to identify and isolate cell populations enriched for more differentiated HPC (CD34+HLA-DR+) and more primitive HPC (CD34+HLA-DR-). The content of CD34+HLA-DR+ and CD34+HLA-DR- cells in the PB of group A patients was significantly greater than that observed in the PB of group B patients. In addition, HD-CTX plus C-HGF mobilization resulted in the appearance of greater numbers of PB colony-forming units-granulocyte/macrophage, -granulocyte/erythroid/macrophage/megakaryocyte, and -megakaryocyte (CFU-GM, CFU-GEMM, and CFU-Mk), and burst-forming units-erythroid and -megakaryocyte (BFU-E and BFU-Mk) than those observed in the PB of group B patients (p < 0.01). CD34+HLA-DR- cells isolated from the PB of group A patients were capable of initiating long-term hematopoiesis in vitro, which persisted for 10 weeks, while CD34+HLA-DR- cells obtained from the PB of group B patients were capable of sustaining long-term hematopoiesis in vitro for only 4 weeks. As determined by a limiting dilution analysis of group A PB CD34+HLA-DR- cells, the frequency of cells capable of giving rise to hematopoietic progenitor cells (pre-CFC) after 2 weeks in liquid culture was 4.3% (range 1.0-8.3%). Pre-CFC constituted 0.01% (range 0.001-0.02%) of group A PB mononuclear cells, and 151 pre-CFC were calculated to be present in 1 mL mobilized PB (range 20-310/mL). These results suggest that peripheral blood mononuclear cells (PBMC) collected by leukapheresis following HD-CTX plus C-HGF mobilization contain not only differentiated HPC but also more primitive HPC.

Blood Transfusion, Autologous↗
PubMed1993

A single B1 subunit mapped to mouse chromosome 7 may be a common component of Na channel isoforms from brain, skeletal muscle and heart.

A beta 1 subunit associated with one or more isoforms of brain voltage-sensitive Na channels has previously been cloned, sequenced and expressed. Northern and Western blot analyses have suggested that homologues to this protein are expressed in skeletal muscle and heart. Here, reverse transcriptase-polymerase chain reaction (RT-PCR)/cloning reveals that transcripts encoding identical beta 1 subunit ORFs are expressed in adult rat brain, skeletal muscle and heart. Heterologous co-expression of beta 1 with brain (RIIA) and skeletal muscle (mu 1) alpha subunits caused a stabilization of normal, rapidly inactivating (mode 1) gating relative to anomalous, non-inactivating (mode 2) states and a negative shift in steady state inactivation. Chromosome mapping of the beta 1 subunit showed a single locus (Scn1b) in mouse chromosome 7 1.8 cM (+/- 1.2 cM) distal to D19F11S1h and 0.9 cM (+/- 0.9 cM) proximal to Pkca. This locus is in the region of the mouse mutant "quivering," characterized by a variety of neurological disorders and muscle paralysis. A mutation in a single beta 1 subunit forming functional complexes with multiple Na channel isoforms could underlie these deficits.

Animals↗
PubMed1993

In vivo administration of recombinant methionyl human stem cell factor expands the number of human marrow hematopoietic stem cells.

A growing number of in vitro studies suggest that recombinant human stem cell factor (SCF) is capable of augmenting the proliferative capacity of human hematopoietic progenitor cells (HPC) and stem cells (HSC). We further evaluated this biologic effect by analyzing the response of bone marrow (BM) HPCs and HSCs to the administration of SCF in eight patients with locally advanced or metastatic breast cancer who were enrolled in an ongoing phase I study. SCF was administered for 14 days by daily subcutaneous injection at dosages of 10, 25, or 50 micrograms/kg/d. BM CD34+ HLA-DR+ and CD34+ HLA-DR- CD15- cells, previously shown by our laboratory to be enriched for various classes of differentiated and primitive HPCs, respectively, were quantitated in BM samples on day 0 (pretreatment) and day 15 (posttreatment). These CD34+ HLA-DR+ and CD34+ HLA-DR- CD15- cells were then isolated by cell-sorting and assayed for several classes of HPCs, including the high--proliferative potential colony-forming cell (HPP-CFC), the burst-forming unit--megakaryocyte (BFU-MK), and the long-term BM culture--initiating cell (LTBMC-IC). SCF administration resulted in a 3.3-fold (range, 1.4- to 18.8-fold; P = .018) increase in the absolute numbers of CD34+ cells, a 3.7-fold (range, 1.2- to 8.2-fold; P = .028) increase in the absolute numbers of CD34+ HLA-DR+ cells, and a 2.4-fold (range, 1.1- to 29.3-fold; P = .010) increase in the absolute numbers of CD34+ HLA-DR- CD15- cells. Following the infusion of SCF, a statistically significant increase in the absolute numbers of HPP-CFC (P = .018), BFU-MK (P = .046), CFU-granulocyte, erythrocyte, monocyte, megakaryocyte (CFU-GEMM: P = .043), BFU-erythrocyte (BFU-E; P = .043), CFU-granulocyte, macrophage (CFU-GM; P = .045), and CFU-megakaryocyte (CFU-MK; P = .028) per milliliter of marrow was observed. Stromal cell-free LTBMCs supplemented with SCF and interleukin-3 (IL-3), initiated with CD34+ HLA-DR- CD15- cells obtained on day 0, produced viable cells for 9.6 weeks, compared with 11.5 weeks for LTBMCs initiated with CD34+ HLA-DR- CD15- cells obtained on day 15. Cumulative cellular production by LTBMCs initiated with day 15 CD34+ HLA-DR- CD15- cells was statistically greater than that by day 0 LTBMCs (P = .031). These same cultures produced CFU-GM for 6.3 weeks (day 0) versus 9 weeks (day 15).(ABSTRACT TRUNCATED AT 400 WORDS)

Antigens, CD↗
PubMed1993

Role of cyclic GMP in the mediation of circadian rhythmicity of the adenylate cyclase-cyclic AMP-phosphodiesterase system in Euglena.

Cyclic AMP (cAMP) and cyclic GMP (cGMP) are two second messengers that have been proposed to act as a dualistic system in biological regulation. To determine if cGMP plays a role in the mediation of circadian rhythmicity of the adenylate cyclase (AC)-cAMP-phosphodiesterase (PDE) system in the achlorophyllous ZC mutant of the unicellular flagellate Euglena, the levels of cAMP and cGMP were monitored in synchronized cell populations, and the effects of the cGMP analog 8-bromo-cGMP (8-Br-cGMP) and the cGMP inhibitor 6-anilinoquinoline-5,8-quinone (LY 83583) on the activity of AC and PDE, as well as on the level of cAMP, were measured in vivo. A bimodal, 24-hr rhythm of cGMP content was found in both dividing and nondividing cultures in either a 12-hr:12-hr light-dark cycle or constant darkness. The peaks and troughs of the cGMP rhythm occurred 2 hr in advance of those of the cAMP rhythm that has been reported previously. The addition of 8-Br-cGMP at different circadian times increased the cAMP level in vivo by two to five times, whereas LY 83583 reduced the amplitude of the cAMP rhythm so that it disappeared. The effects of 8-Br-cGMP on the activity of AC and PDE were circadian phase-dependent and consistent with the changes in cAMP content. These findings suggest that cGMP may serve as an upstream effector that mediates the cAMP oscillation by regulation of the AC-cAMP-PDE system.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1993

The in vitro and in vivo effects of stem cell factor on human hematopoiesis.

The c-kit ligand or stem cell factor (SCF) and the c-kit ligand receptor (KR) are thought to play pivotal roles in the regulation of human hematopoiesis. When added to interleukin 3 (IL-3) and/or granulocyte-macrophage colony stimulating factor (GM-CSF), SCF has an especially profound effect on the in vitro proliferation of several classes of primitive hematopoietic progenitor cells including the burst forming unit megakaryocyte (BFU-MK), the high proliferative potential colony forming cell (HPP-CFC) and the long-term bone marrow culture-initiating cell (LTBMC-IC). These primitive hematopoietic progenitor cells are present in a CD34+HLA-DR- fraction of marrow which has in vivo marrow populating ability and thereby resembles the pluripotent hematopoietic stem cell. Furthermore, the CD34+HLA-DR- marrow subpopulation which expresses KR contains virtually all of the marrow BFU-MK, HPP-CFC and LTBMC-IC, indicating that the human stem cell is KR positive. The addition of SCF, IL-3 and GM-CSF to suspension cultures initiated with CD34+HLA-DR- cells results in an exponential expansion of the numbers of hematopoietic progenitor cells. Large numbers of such progenitor cells generated ex vivo may be useful as transfusion products for the treatment of chemotherapy induced cytopenias. The therapeutic potential of the in vivo administration of SCF has also been evaluated in a phase I trial of recombinant methionyl SCF. SCF administration led to an increase in both differentiated and primitive hematopoietic progenitor cells within the marrow. Such studies suggest that in vivo SCF administration may be useful for improving the quality of bone marrow grafts to be used either for autologous or allogeneic bone marrow transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Neoplasms↗
PubMed1993

In patients receiving dopamine infusions for treatment of shock do free radicals convert dopamine to 6-hydroxydopamine?

Free hydroxyl radicals react with dopamine in vitro to produce the neurotoxin 6-hydroxydopamine (6-OHDA). If 6-OHDA were produced in vivo it could destroy central and/or peripheral neurons. Free radicals are produced in patients with cardiovascular or toxic shock. These patients are often treated with intravenous dopamine infusions. Using a newly developed method for measuring 6-OHDA in biological samples, we have examined blood from 15 patients receiving dopamine infusions for treatment of shock. 6-OHDA neither binds to nor elutes from either alumina or ion-exchange resins; therefore we used ODA-silica (Sep-Pak) to prepare samples for HPLC analysis with electrochemical detection. 6-OHDA disappeared rapidly from whole blood or serum at room temperature but was stable at -70 degrees C in an HClO4 extract. Recovery from Sep-Pak was 95% and detection limit 10 nmol/L. We repeated the experiments that showed in vitro hydroxyl radical conversion of dopamine to 5- and 6-OHDA. We detected neither 5- nor 6-OHDA in plasma samples from patients receiving dopamine infusions at 10-28 micrograms kg-1 min-1. Plasma dopamine in these patients was 1-5 mumol/L. We conclude that any 6-OHDA produced by hydroxyl radical attack in vivo is rapidly scavenged by endogenous substances containing sulfhydryl groups.

Chromatography, High Pressure Liquid↗