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Biomedical subjects

M J Murphy

Publications and source records attributed to M J Murphy.

At least 73 records · Page 4Linked to original sources
PubMed1995

HIMeg-1, a cell line derived from a CML patient, is capable of monocytic and megakaryocytic differentiation.

We have characterized HIMeg-1, a subclone of the promegakaryoblastic cell line HIMeg, in terms of its capability of proliferation and differentiation when it is exposed to various agents. We observed that phorbol 12-myristate 13-acetate (PMA) arrested HIMeg-1 growth and induced expression of monocytic surface antigens CD11c and CD14, but not the megakaryocytic surface antigen CD14a. In addition, PMA treatment of HIMeg-1 led to rapid activation of mRNA expression of egr-1, a transcription factor involved in regulating differentiation of hematopoietic progenitor cells. On the other hand, treatment of HIMeg-1 with the activated peripheral blood lymphocyte-conditioned medium (PBL-CM) resulted in greatly enhanced incorporation of 3H-thymidine into newly synthesized DNA. This enhanced 3H-thymidine incorporation appears to be specific to HIMeg-1 since the same concentrations of PBL-CM had little effect on the growth of the megakaryoblastic leukemia cell line SAM-1. The PBL-CM-induced DNA synthesis in HIMeg-1 was associated with activation of CD41a and CD41b surface antigen expression and down-regulation of expression of the erythroid marker glycophorin A and the early myeloid surface antigen CD33. HIMeg-1 capable of responding differentially to PMA and PBL-CM by changing its growth rate as well as its differentiation patterns will provide an ideal model to study the underlying mechanism regulating lineage restriction of hematopoietic progenitor cells.

Antigens, CD↗
PubMed1994

In vivo-in vitro correlation of myelotoxicity of 9-methoxypyrazoloacridine (NSC-366140, PD115934) to myeloid and erythroid hematopoietic progenitors from human, murine, and canine marrow.

BACKGROUND: 9-Methoxypyrazoloacridine (PZA) is an anticancer agent that shows selectivity of action for carcinomas over leukemias. It also has nearly equal potency against cycling and quiescent or hypoxic and normoxic target cells. Phase I trials of PZA in humans are nearing completion. PURPOSE: This study was conducted to determine (a) if PZA is directly inhibitory to hematopoietic cells and, if it is, to characterize the inhibition pharmacodynamically, (b) whether species-specific differences in direct toxicity could explain differences in myelosuppression in mice, dogs, and humans, and (c) whether in vitro data correlate with in vivo myelosuppression data. METHODS: In vitro clonogenic assays of hematopoietic progenitors of myeloid and erythroid lineages from human, canine, and murine femoral marrow were used to measure the direct toxicity of PZA. Results from these assays were compared on an area-under-the-curve (AUC) basis to clinical myelosuppression data. RESULTS: On the basis of maximum tolerated concentrations, canine hematopoietic progenitors are most susceptible to PZA, followed by human and then murine progenitors. We found no difference in susceptibility to PZA toxicity between the human progenitors of myeloid and erythroid lineages. Both concentration and duration of exposure contribute to the in vitro toxicity of PZA. In contrast to antimetabolites, the in vitro toxicity of PZA could be minimized at a given AUC by lowering drug concentration and prolonging the period of exposure. On an AUC basis, the in vitro data are consistent with limited in vivo myelosuppression data from preclinical models and correlate with neutropenia data from a phase I trial. CONCLUSIONS: PZA directly inhibits hematopoietic progenitors, an action that is responsible for the myelosuppression observed in humans. Human marrow appears able to compensate for the loss of up to 35% of its myeloid progenitors, in that peripheral neutrophil counts remain unchanged at that level of loss. Although in vivo studies show that prolonged infusion reduces myelosuppression at a given total dose in both rodent and canine models, pharmacokinetic differences make it unlikely that this approach will benefit human patients. IMPLICATIONS: The in vitro data quantitatively predict the AUCs at maximum tolerated dose in preclinical models and human patients. Thus, in vitro clonogenic assays of myelotoxic agents can provide data that make both preclinical toxicology testing and clinical trial planning and interpretation more efficient and accurate.

Acridines↗
PubMed1994

In vitro characterization of the myelotoxicity of cyclopentenyl cytosine.

We studied the toxicity of a new experimental anticancer drug, cyclopentenyl cytosine (CPE-C), to human and murine hematopoietic progenitor cells in vitro. Due to CPE-C's in vivo myelotoxicity, it was important to characterize its potential adverse effects on human marrow cells during preclinical development of the drug. Marrow cells were exposed to CPE-C for either 1 h prior to addition in clonal assays or continuously during their culture period. The inhibitory effects of CPE-C on myeloid (CFU-gm) and erythroid (CFU-e, BFU-e) colony formation were concentration- and time-dependent, with continuous CPE-C exposure being significantly more inhibitory than 1-h exposure. The results of both exposure experiments were combined to investigate colony inhibition as a function of overall drug exposure (concentration x time, AUC) and data analyzed by the nonlinear Emax equation. Human and murine CFU-gm had similar AUC-response curves and IAUC70 values (i.e., AUC at 70% colony inhibition) of 40.8 and 41.9 microM h, respectively. In contrast, murine CFU-e and BFU-e were more sensitive to CPE-C, having lower IAUC70 values (both, 21.1 microM h) than human CFU-e and BFU-e (107.8 and 33.0 microM h, respectively). This difference was most prominent with the late erythroid progenitor, CFU-e, in that the human cells were 5 times more resistant to inhibition by CPE-C. CPE-C was myelotoxic in vitro to human and murine marrow cells and toxicity correlated with overall drug exposure.

Animals↗
PubMed1994

Antiparasitic and antiproliferative effects of indoleamine 2,3-dioxygenase enzyme expression in human fibroblasts.

Studies were carried out to evaluate the proposed role of indoleamine 2,3-dioxygenase (INDO) induction in the antimicrobial and antiproliferative effects of gamma interferon (IFN-gamma) in human fibroblasts. The INDO cDNA coding region was cloned in the pMEP4 expression vector, containing the metallothionein (MTII) promoter in the sense (+ve) or the antisense (-ve) orientation. Human fibroblasts (GM637) stably transfected with the sense construct expressed INDO activity after treatment with CdCl2 or ZnSO4, but cells transfected with the antisense construct did not. The growth of Chlamydia psittaci was strongly inhibited in INDO +ve cells but not in INDO -ve cells after treatment with Cd2+ or Zn2+. The inhibition correlated with the level of INDO activity induced and could be reversed by the addition of excess tryptophan to the medium. The growth of Toxoplasma gondii was also strongly inhibited in INDO +ve cells but not in INDO -ve cells after treatment with Cd2+. Expression of Cd(2+)-induced INDO activity also inhibited thymidine incorporation and led to cytotoxicity in INDO +ve cells but not in INDO -ve cells. Thus, the induction of INDO activity by IFN-gamma may be an important factor in the antimicrobial and antiproliferative effects of IFN-gamma in human fibroblasts.

Animals↗
PubMed1994

Regional and supraregional biochemistry services in Scotland: a survey of hospital laboratory users.

AIM: To ascertain the views of Scottish hospital laboratory users on aspects of regional and supraregional biochemical services offered by the Institute of Biochemistry at Glasgow Royal Infirmary. METHODS: A questionnaire was circulated asking questions or inviting opinions under various headings, including current patterns of usage of the services provided, availability of information on specimen collection requirements and reference ranges, current arrangements for transport of specimens, turnaround times for delivery of reports, layout and content of request and report forms, quantity and quality of interpretive advice, potential changes in laboratory services, and overall impression of the services provided. Opportunities were provided for free text comment. The questionnaire was circulated in 1992 to heads of department in 23 Scottish hospital biochemistry laboratories. RESULTS: Twenty one replies were received. Services used widely included trace metals/vitamins (n = 20) and specialised endocrine tests (n = 19). Other services also used included specialised lipid tests (n = 13), toxicology (n = 12), thyroid function tests (n = nine), and tumour markers (n = eight). Fifteen laboratories used one or more of the services at least weekly. Most (n = 20) welcomed the idea of a handbook providing information on specimen collection and reference ranges. Nine identified loss of specimens as a problem. Other perceived problems included the absence of reference ranges from report forms, quantity and quality of interpretive advice, and turnaround times of some tests. Overall impressions of the service(s) offered were very good (n = 12); adequate (n = seven); poor (n = one). CONCLUSIONS: Useful information was obtained about patterns of use and transport arrangements. Areas identified as requiring follow up included provision of information, alternative ways of communicating reports, and improvement in quantity and quality of interpretive advice.

Attitude of Health Personnel↗
PubMed1994

On-call duties in chemical pathology: a survey of junior medical staff in the UK.

To ascertain the extent of variation in out-of-hours duties among trainees in chemical pathology in the UK questionnaires were sent to 81 junior medical staff in 1992. Replies were received from 63 (78%). Although most had participated in an advisory rota, only 41 (65%) had participated in an analytical rota. Nine (14%) had participated in specialist analytical rotas, while 13 (21%) had experience of multidisciplinary rotas and only eight (13%) had experience of rotas involving clinical responsibility. Only 10 (16%) regularly reviewed their work on call with their senior medical staff. There was no single method of requesting tests out of hours in the trainees' laboratories and there was also considerable variation with respect to the tests available out of hours. It is concluded that sufficient variation exists in the on-call experience gained by junior medical staff in chemical pathology to raise concern about the quality of training in out-of-hours work.

Adult↗
PubMed1994

Molecular cloning of a novel receptor tyrosine kinase, tif, highly expressed in human ovary and testis.

Using a combination of polymerase chain reaction and conventional cDNA library screening approaches, we have cloned and characterized a putative receptor tyrosine kinase termed tif. The extracellular domain of tif has an immunoglobulin-like loop and a fibronectin type III structure. The intracellular domain contains a tyrosine kinase domain. Compared with ryk, a ubiquitously expressed receptor tyrosine kinase, tif expression is tissue-specific with human ovary and testis containing the highest amount of tif mRNA. Many other tested human tissues such as heart, liver, pancreas and thymus do not contain detectable levels of tif mRNA. The molecular cloning and characterization of tif cDNA will facilitate the identification of a potential ligand(s) for the putative receptor and the study of its biological role.

Amino Acid Sequence↗
PubMed1994

Q-switched ruby laser treatment of benign pigmented lesions in Chinese skin.

The Q-switched ruby laser has been demonstrated as an effective choice of treatment for a range of benign pigmented lesions. Its wavelength of 694 nm enables deep penetration of the skin allowing the treatment of both epidermal and dermal lesions. However, this wavelength is selectively absorbed by melanin thereby enabling efficient targeting of the lesion's melanocytes. By utilising a Q-switched pulsewidth of 25 nanoseconds, thermal conduction into surrounding tissues is minimised. Lesions such as nevus of Ota, chloasma, lentigines and cafe au lait have been successfully treated with energy densities ranging from 6 to 12 J/cm2. Four case histories are described in this report. The clinical evidence indicates that pigmented lesions in Chinese skin must be treated with energy densities higher than those used in Caucasian skin to minimise the incidence of hyper-pigmentation. Typically, lesions require a small number of treatments, usually within the range one to six, to effect complete removal. The technique is easy to apply, with no need for anaesthesia, in many cases.

Adult↗
PubMed1993

Multicenter trial of ionic versus nonionic contrast media for cardiac angiography. The Iohexol Cooperative Study.

Contrast agents used for cardiac angiography are different in regard to ionicity, osmolality and physiologic effects. The nonionic contrast media have been shown to have less toxic effects and a better safety profile than do higher osmolar agents. To better assess this risk, clinically stable patients undergoing cardiac angiography were stratified according to the presence of diabetes mellitus, and level of serum creatinine, and then randomized to receive either iohexol (Omnipaque 350) or sodium meglumine diatrizoate (Renografin 76). All adverse events that occurred during and immediately after angiography were tabulated. A multivariate model was used to identify patients at increased risk for adverse outcome. The 1,390 patients were randomized to iohexol (n = 696) or diatrizoate (n = 694). Significant differences were found in the number of patients with contrast media-related adverse (iohexol vs diatrizoate: 10.2 vs 31.6%; p < 0.001) and cardiac adverse (7.2 vs 24.5%; p < 0.001) events. Severe reactions and the need for treatment were more frequent with diatrizoate than with iohexol, but there was no difference in the incidence of death. The presence of New York Heart Association classification 3 or 4 and serum creatinine > or = 1.5 mg/dl predicted a higher incidence of adverse events as a result of contrast media alone. Use of iohexol is associated with a lower incidence of all types of adverse events during cardiac angiography than is diatrizoate.

Adult↗
PubMed1993

Exogenous reinfection with multidrug-resistant Mycobacterium tuberculosis in patients with advanced HIV infection.

BACKGROUND: In the United States there have been recent outbreaks of multidrug-resistant tuberculosis. These outbreaks have primarily involved persons infected with the human immunodeficiency virus (HIV). METHODS: We collected clinical information on 17 patients seen at a New York City hospital who had repeatedly positive cultures for Mycobacterium tuberculosis. Analysis of restriction-fragment--length polymorphisms (RFLPs) was performed on serial isolates of M. tuberculosis obtained from these patients. RESULTS: Six patients had isolates that remained drug-susceptible, and the RFLP patterns of these isolates did not change over time. Eleven patients had isolates that became resistant to antimicrobial agents. The RFLP patterns of the isolates from six of these patients remained essentially unchanged (two strains showed one additional band) despite the development of drug resistance. In five other patients, however, the RFLP patterns of the isolates changed dramatically at the time that drug resistance was detected. The change in the RFLP pattern of the isolate from one patient appeared to be the result of contamination during processing in the laboratory. In the remaining four patients, all of whom had advanced HIV disease, the clinical and microbiologic evidence was consistent with the presence of active tuberculosis caused by a new strain of M. tuberculosis. CONCLUSIONS: Resistance to antituberculous drugs can develop not only in the strain that caused the initial disease, but also as a result of reinfection with a new strain of M. tuberculosis that is drug-resistant. Exogenous reinfection with multidrug-resistant M. tuberculosis can occur either during therapy for the original infection or after therapy has been completed.

AIDS-Related Opportunistic Infections↗
PubMed1993

Downregulation of GATA-1 expression during phorbol myristate acetate-induced megakaryocytic differentiation of human erythroleukemia cells.

Phorbol myristate acetate (PMA) induces the expression of megakaryocyte and/or platelet proteins during terminal differentiation of human erythroleukemia (HEL) cells. However, it is not established whether megakaryocytic differentiation is accompanied by the downregulation of the major erythroid transcription factor GATA-1 and the concomitant loss of the erythrocytic phenotype. Studies of the molecular mechanism of PMA-induced differentiation in HEL cells showed that when HEL cells are treated with PMA, they dramatically decrease the expression of the erythroid-specific gene glycophorin A at the mRNA level but apparently not at the steady-state protein level. In addition, a gel mobility shift assay was used to demonstrate that GATA-1, a major erythroid transcription factor normally present at high levels in HEL cells is downregulated after treatment with PMA. In contrast, the DNA-binding activities of transcription factors AP-1 and SP-1 are upregulated by PMA treatment of HEL cells. Furthermore, Northern blot analysis shows that PMA also downregulates the steady-state level of GATA-1 mRNA in HEL cells. The coordinated negative regulation of glycophorin A mRNA and GATA-1 expression after PMA treatment suggests that downregulation of GATA-1 expression may be partially responsible for the loss of the erythroid phenotype during megakaryocytic differentiation. The reported data also suggest that GATA-1 activity may not be essential for obtaining megakaryocytic phenotype during terminal differentiation in HEL cells.

Base Sequence↗
PubMed1993

Renal clearance measurements of electrolytes in embryonic chickens.

Plasma ion concentrations and renal functions were examined in chick embryos after 9, 12, and 15 days of incubation. Plasma calcium and phosphate values rise steadily and significantly between days 9 and 15 of development. Values of other plasma ions (sodium, potassium, magnesium, sulfate) remain more or less the same during this developmental period. Glomerular filtration rates and urine flow rates decline steadily and significantly during this period of embryogenesis when expressed relative to body weight. Renal clearance values of calcium decrease between day 9 (16% of filtered calcium is excreted) and day 15 (4%). The latter value is the same as in birds after hatching and indicates that calcium is being conserved by the kidney of the chick during late embryogenesis. Other ions that appear to be conserved by the embryonic kidney are sodium and sulfate, whereas high percentages of filtered phosphate, potassium, and magnesium are excreted. Except for calcium, there was no significant difference between the renal handling of ions by the mesonephric kidney (functional in 9 day embryos) and the metanephric kidney (predominant in the 15 days embryos).

Analysis of Variance↗
PubMed1993

Megakaryocytopoiesis and platelet production: does stem cell factor play a role?

Megakaryocytopoiesis, resulting in the production and release of platelets, is a multistage procession of cellular differentiation and maturation which is regulated by a constellation of cytokines. Since thrombocytopenia is a frequent dose-limiting toxicity of chemotherapy, newly-identified cytokines have been actively investigated for their potential megakaryocyte/platelet-promoting properties. Stem cell factor (SCF, also known as mast cell growth factor, Steel factor or Kit ligand) has been found to synergize with GM-CSF, IL-6, IL-3, IL-11 or Epo to increase the numbers of megakaryocyte-containing colonies (i.e., CFU-Meg, BFU-Meg, CFU-GMM, CFU-GEMM). On the other hand, SCF increased the number of megakaryocytes per colony in the presence of IL-3, GM-CSF or IL-6. SCF also stimulated the proliferation of specific megakaryocytic cell lines (i.e., CMK, M-07e). SCF did not, however, alter megakaryocyte markers or increase cell ploidy. Thus, SCF appears to expand the committed myeloid progenitor compartments, rather than increase the rate of megakaryocyte maturation or the number of platelets released. We describe studies in which SCF stimulated murine CFU-Meg alone and in the presence of IL-3. However, a decrease in cultured cell plating density resulted in ablation of this SCF-stimulation of CFU-Meg colonies. CFU-Meg colony stimulation by SCF was dose dependent, even under serum-free conditions. The effects of SCF in other in vitro and in vivo animal model systems are reviewed.

Animals↗
PubMed1993

Megakaryocyte colony-stimulating factor (Meg-CSF) is a unique cytokine specific for the megakaryocyte lineage.

The regulation of megakaryocytopoiesis and platelet production has not yet been clearly elucidated. Several cytokines have been shown to be capable of producing megakaryocyte colonies from bone marrow [i.e. Interleukin (IL)-3, granulocyte-macrophage (GM)-colony-stimulating factor (CSF), erythropoietin (Epo)]. In addition, other activities have been reported to stimulate megakaryocyte precursors, yet a megakaryocyte-CSF (Meg-CSF) has not been purified to homogeneity and IL-3, GM-CSF and/or Epo often contaminate purification attempts which could account for the activities. A Meg-CSF has been isolated from the urine of patients with aplastic anaemia and purified by sequential ultrafiltration, cation exchange, G-50 chromatography, preparative PAGE, chromatofocusing and cation exchange HPLC. The activity of this material is 2-4 x 10(4) CFU-Meg/mg as measured in a murine marrow, serum-containing assay. This activity also stimulates CFU-Meg in the absence of adherent accessory cells and in serum-free cultures, indicative of the direct stimulation on CFU-Meg. Immunoassays, colony forming assays, and proliferation assays demonstrate that purified Meg-CSF has no GM-CSF, IL-3, M-CSF, G-CSF or IL-1 alpha, -3, -6, -9 and -11. In confirmation of these results, neutralizing antibody to IL-6 also did not abrogate Meg-CSF activity. Therefore the previously-reported megakaryocyte colony-stimulating activity in purified aplastic anaemia patient urine is due to a unique cytokine: Meg-CSF.

Anemia, Aplastic↗
PubMed1993

Myelotoxicity of rifabutin and 3'-azido-3'-deoxythymidine, alone and in combination, to human hematopoietic progenitor cells in vitro.

Mycobacterial infection is a common complication of acquired immunodeficiency syndrome (AIDS) frequently requiring antimycobacterial medication. It was of interest to determine if one such agent, rifabutin, could be tolerated by AIDS patients in conjunction with 3'-azido-3'-deoxythymidine (AZT) therapy. We evaluated the in vitro myelotoxic effects of rifabutin on human hematopoietic progenitor cells, alone and in combination with AZT (rifabutin: AZT, 1:10 ratio) over a range of concentrations in a microcapillary assay. Both rifabutin and AZT at 5 microM were moderately toxic to hematopoietic progenitors, inhibiting colony formation by 57-65% and 59-63%, respectively. The combination of rifabutin (5 microM) and AZT (50 microM) inhibited colony formation by 59-73%. Granulocyte-macrophage progenitors were less sensitive to this combination than erythroid progenitors. The combination of ribabutin and AZT did not exceed the in vitro myelotoxicity to human progenitors of AZT alone. These results suggest that rifabutin may be tolerated in AIDS patients, with no anticipated increase in myelotoxicity when given with AZT.

Cells, Cultured↗