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Biomedical subjects

M J Murphy

Publications and source records attributed to M J Murphy.

At least 181 records · Page 10Linked to original sources
PubMed1983

In vivo stimulation of murine granulopoiesis by human urinary extract from patients with aplastic anemia.

Significant in vivo stimulation of granulopoiesis was induced in mice by the administration of an extract from the urine of patients with aplastic anemia (AA). Sialic acid has been identified as an important molecular component for the in vivo biological activity of this granulopoietic factor, "granulopoietin," which is distinct and different from endotoxin. Urine from patients with AA was successively fractionated by Sephadex G-50 and DEAE-cellulose chromatography. The resultant extract, which we refer to as AA urinary extract, contained approximately equal to 44 international units of erythropoietin per A unit of protein and induced 15,000 colonies of granulocyte/macrophage precursor cells (granulocyte/macrophage colony-forming units, CFU-gm) per A unit of protein with mouse bone marrow. Eight daily intraperitoneal injections of this extract in mice induced a 6.2-fold increase in peripheral blood granulocytes and a 14.6-fold increase of splenic CFU-gm, with concomitant increases in the proliferation rates of CFU-gm in both bone marrow and spleen. Pretreatment of the AA urinary extract with sialidase significantly diminished these granulopoietic effects in vivo (P less than 0.001). In contrast, both extracts (i.e., native AA and sialidase-treated AA urinary extracts) revealed high granulocyte/macrophage colony-stimulating factor activity in vitro when clonal assays were performed with mouse bone marrow. Increased in vivo and in vitro granulopoietic activities were found in the concanavalin A "break-through" fraction, indicating that these activities were due to protein(s) that did not bind to the lectin. These results reveal that this urinary extract from patients with AA is capable of inducing significant granulopoiesis in mice and that sialic acid is an important component in the maintenance of this granulopoietic effect in vivo but not in vitro.

Anemia, Aplastic↗
PubMed1983

Predicting phenytoin dosages using Bayesian feedback: a comparison with other methods.

A Bayesian feedback technique for predicting phenytoin dosage was compared to other dosing methods. Sixty-nine cases were selected on the basis of apparent reliability from 103 medical charts of epileptic patients with multiple phenytoin levels on different dosage regimens. Two published nomograms and a graphical, or computational, technique were compared to the Bayesian technique. Each method was assessed for absolute predictability using measures of bias and precision, i.e., mean percent error and root mean squared percent error, respectively. For a single previous data pair, the Bayesian method was similar to a published nomogram with regard to bias and precision. For multiple data pairs, the graphical or simultaneous equation technique tended to be less biased, but the Bayesian method had better precision. However, none of these differences was statistically significant (p greater than 0.05). The Bayesian method yielded the lowest percentage of predicted doses that exceeded 110% of the actual dose. The Bayesian method conveniently provides a single method applicable to the use of either single or multiple concentration-dosage data pairs and results in fewer extreme dosing errors.

Adult↗
PubMed1983

Erythroid stem cells in Rauscher viral erythroleukemia.

Results reported herein describe the expansion of erythroid stem cells (CFU-e and BFU-e) from marrow and spleen cells from mice infected with Rauscher leukemia virus (RLV). Maximum colony numbers were seen by 5 weeks after viral inoculation. The increase in splenic CFU-e and BFU-e was related to development of splenomegaly, the latter being a characteristic feature of murine oncornavirus infection. Both splenic and marrow RLV-derived CFU-e were erythropoietin (Ep) dependent. However, splenic and marrow RLV-derived BFU-e proliferation occurred at Ep levels considered suboptimal for normal colony formation. This increased erythroid stem cell proliferation may be due in part to the increased demand on erythropoiesis as a result of the profound fatal anemia which occurs in RLV-induced erythroleukemia. These studies suggest that factors operating at the level of BFU-e may enhance erythropoiesis, and hence may be a direct result of murine oncornavirus infection.

Adult↗
PubMed1983

Further studies on the in vitro enhancement of erythroid stem cell (CFU-e and BFU-e) colony formation by ouabain.

The cardiac glycoside ouabain has been shown to stimulate erythroid stem cell (CFU-e/BFU-e) colony formation while inhibiting both granulocyte/macrophage precursor cell (CFU-gm) and murine spleen stem cell (CFU-s) colony formation. We have examined the ability of ouabain to increase both CFU-e/BFU-e colony formation by performing time-delay and temperature-dependent studies. After pre-exposure of marrow cells to ouabain (10(-15) M) at temperatures of 27, 37, or 4 degrees C, erythropoietin (Ep) was added after time-delays ranging from 10 s to 60 min. The ouabain-induced increase in CFU-e/BFU-e colony formation was observed up to an Ep-delay of 20 s, after which time the enhancing effect of ouabain was diminished. This increase was also observed when marrow cells were first exposed to Ep prior to a similar delayed exposure to ouabain. The enhancement effect seen with ouabain was also temperature dependent, since at 37 degrees C an earlier time increase in CFU-e/BFU-e colony formation was observed when compared to identical studies performed at either room temperature or 4 degrees C. These studies suggest that ouabain-induced elevations in erythroid stem cell colony formation involve mechanisms that are both time and temperature dependent.

Animals↗
PubMed1983

Comparative effects of chlorozotocin and BCNU on hematopoietic precursor cells.

Comparative studies to determine the suppressive effects of chlorozotocin (2-[3-(2-chloroethyl)-3-nitrosoureido]-D-glucopyranose) and BCNU (1,3-bis[2-chloroethyl]-1-nitrosourea) on mouse and human hematopoietic precursor cells: granulocyte-macrophage precursor cells (CFU-gm), late erythroid precursor cells (CFU-e), and early erythroid precursor cells (BFU-e) were performed after in vitro incubation of 1 h with drug concentrations based on clinical administration levels. The suppressive effect of chlorozotocin on CFU-gm, BFU-e, and CFU-e hematopoietic precursor cells in the mouse was less than that of BCNU with the most significant difference seen in CFU-e colony formation. For human hematopoietic progenitor cells, however, the suppressive effect of chlorozotocin was far less than that of BCNU. When the effects of 40 micrograms/ml of chlorozotocin and 20 micrograms/ml of BCNU on human marrow were compared, there were statistically significant differences found for CFU-gm colony formation, and BFU-e and CFU-e colony numbers were significantly different for the two drugs at all comparable concentrations tested. Our results confirm the clinical data, and establish that the effects of chlorozotocin on human hematopoietic precursor cells are minimal.

Animals↗
PubMed1982

Hydromineral balance in the chick embryo: effects of hypophysectomy.

The developing chick embryo exhibits a regular pattern of accumulation and reabsorption of fluid in its extraembryonic compartments. Fluid volume (measured by dye dilution) peaks at Day 14 in both the allantois (12.4 ml) and the amnion (5.1 ml). The standard experimental procedure of removing 2 ml of albumen at 33-36 hr of incubation does not alter this pattern, but leads to a maximum decrease in fluid volume of ca. 1 ml in both amniotic and allantoic compartments. Although [Na] and [Cl] remain essentially constant in the serum, they steadily decrease in the allantois (remaining substantially below serum levels). In the amnion, [Cl] is maintained above that of serum, whereas [Na] falls below serum [Na] by Day 14. In the Day 12 (stage 38) embryo, hypophysectomy (HX) causes a substantial increase in the allantoic fluid volume and [Na] and [Cl], thus resulting in a 166% increase in total Na and Cl over that of sham-operated embryos. By contrast, HX did not alter amniotic fluid volume, although it did decrease [Na] and to a lesser degree, [Cl]. Serum [Na], but no [Cl], was reduced by HX. HX abolished the normally steep ionic gradients maintained between the allantois and both serum and amnion. Thus, the most dramatic effects of HX at Day 12 are on the allantois, which accumulates both Na and Cl at the expense of the amnion and serum. This suggests that pituitary hormones may normally act by Day 12 to reduce urinary volume and electrolyte excretion and/or to increase fluid and electrolyte reabsorption from the allantois.

Allantoin↗
PubMed1982

Nevoid basal cell carcinoma syndrome and epilepsy.

Four patients affected with the nevoid basal cell carcinoma syndrome and recurrent seizures are described and the pertinent literature is reviewed. Three of the patients had multiple basal cell carcinomas and cutaneous nevi, dentigerous cysts, and skeletal anomalies characteristic of the syndrome. The seizures had their onset in childhood and were generalized tonic-clonic in three patients and both tonic-clonic and complex partial in the fourth. Focal neurological deficits were found in only one patient. Pneumoencephalography in two patients and head CT scan in a third were negative. Electroencephalography showed focal spike discharges in one patient, bilateral anterior paroxysmal slowing in another, and nonspecific shifting temporal theta transients in the other two cases. Psychometric testing yielded full-scale scores ranging from 39 to 84. In addition to mental retardation, congenital communicating hydrocephalus, and medulloblastoma, seizures should be included among the neurological manifestations of the nevoid basal cell carcinoma syndrome.

Basal Cell Nevus Syndrome↗
PubMed1982

Effects of ouabain and valinomycin on in vitro erythroid colony formation (CFU-e and BFU-e).

Ouabain enhances the number of clonally derived erythroid stem cell colonies (CFU-e and BFU-e) from normal murine bone marrow. Ouabain is known to inhibit lymphocyte proliferation by blocking the Na+/K+ pump. To further explore these Na+/K+ ATPase-associated interrelationships, valinomycin, an inhibitor of Na+/K+ ATPase was employed. The addition of valinomycin (10(-11) to 10(-15) M) in the presence of ouabain and erythropoietin (Ep) did not alter the erythroid colony-forming stimulation which was characteristic of cultures in which only ouabain (10(-15) M) and Ep were added. Valinomycin did effectively block both CFU-e and BFU-e formation when it was added in the range of 10(-3) to 10(-9) M. The mechanism of this valinomycin-induced inhibition and ouabain stimulation is discussed.

Animals↗
PubMed1982

Comparative effects of chemotherapeutic drugs on human and murine hematopoietic progenitors in vitro.

Using semi-solid clonal assay systems, the cytocidal effects of chemotherapeutic drugs on hematopoietic progenitors (CFU-gm, BFU-e, CFU-e) were compared with their effects on K-562 human leukemia cells. The chemotherapeutic drugs used for these experiments were daunorubicin, cytosine arabinoside, vincristine, methotrexate, bis-chlorethyl-nitrosourea and chlorozotocin. After the cells were exposed for either 1 or 24 h to several concentrations of each drug, clear differences in suppressive effects were seen. The experimental applications of this technology and the clinical implication of these results are discussed.

Animals↗
PubMed1982

Modulation of murine in vitro erythroid and granulopoietic colony formation by ouabain, digoxin and theophylline.

Ouabain has been shown to increase the number of clonally derived erythroid stem cells, CFUE and BFUE, from normal murine bone marrow. We report here that digoxin and theophylline also enhance erythroid stem cell colony formation, in the presence of suboptimal concentrations of erythropoietin (Ep) (0.01 IU/ml) in methylcellulose culture. Both digoxin and theophylline increased CFUE colony formation optimally at 10(-8) M (29-81% respectively). The increase in BFUE colony formation occurred at 10(-10) M (35-76% respectively), suggesting that BFUE are more sensitive to the enhancing properties of these compounds. In addition, digoxin theophylline and ouabain were effective inhibitors of clonally derived granulocyte-macrophage progenitor cells, CFUC, from normal murine marrow plated in double layer agar in the presence of 10% L-cell conditioned medium (LCM). The degree of reduction in colony formation by CFUC ranged from 11% to 100%. Digoxin and theophylline were inhibitory for CFUC in the range of 10(-2) to 10(-12) M; however, ouabain was inhibitory over a broader concentration range of 10(-4) to 10(-18) M, suggesting that ouabain has a greater influence on committed hematopoietic progenitor cell colony formation. Both ouabain and digoxin have the property of binding to Na+/K+ATPase. This may mediate the alteration of hematopoietic differentiation. Theophylline, an adenyl cyclase inhibitor, may act through alterations in cyclic nucleotide levels. These studies further indicate that digoxin, theophylline and ouabain may serve as useful tools in elucidating the underlying mechanisms of how specific growth factors influence hematopoietic growth and differentiation.

Animals↗
PubMed1982

Colony stimulating factor in human mixed leukocyte cultures.

Colony stimulating factor (CSF) is important for granulocyte/macrophage proliferation and differentiation. We investigated the relationship between the immune reactivity and the production of CSF by using two-way mixed leukocyte cultures (MLC) prepared from human peripheral mononuclear cells obtained with the aid of a blood cell separator. Assessed over 9 days of MLC incubation, the level of CSF in the supernatant reached a maximum at day 7 and then decreased. Optimal number of MLC cells ranged from 1 X 10(6)/ml to 2 X 10(6)/ml; CSF activity decreased at a cell concentration of 4 X 10(6)/ml. There was a differential sensitivity between cluster formation and colony formation to MLC-CSF. MLC-CSF is not species specific and hence, can stimulate both human and mouse CFU-c. MLC-conditioned medium (MLC-CM) appears to be a potentially useful source of CSF.

Animals↗
PubMed1982

Partial purification and biological properties of thrombopoietin extracted from the urine of aplastic anemia patients.

Thrombopoietic (Tpo) and megakaryocyte-colony stimulating (Meg-CSF) activities were found in urinary extracts from patients with aplastic anemia. Preparative biochemical extractions were accomplished using Sephadex G-50 and DEAE-cellulose column chromatography. The biological activities of these extracts were assessed using not only an in vivo assay but were also examined in vitro employing the clonal development of megakaryocyte colonies. Both in vivo, as well as in vitro, biological activities were detected in the batch fraction which was stepwise eluted from DEAE-cellulose between 0.022 M NaCl in 0.016 M NaH2PO4 and 0.15 M NaCl in 0.05 M Na2HPO4 as a single fraction. When 0.4 mg of this fraction was injected daily into rats, a marked thrombopoiesis ensued producing an increase of 40% over initial platelet counts by 3 days after administration. This was followed by a decrease in platelets to a subnormal range by 21 days after the injection. Hemoglobin concentration gradually increased from 5% above initial value by day 7 to 20% above initial value by day 21. The effect of neuraminidase (NAse) on the properties of this extract was also examined. NAse-treated extracts, similar to the native extracts described above retained Tpo activity. Changes in megakaryocyte numbers in the spleen and bone marrow of rats were assayed with both the NAse-treated extract as well as with the native extract. A remarkable increase in megakaryocyte numbers, threefold above the normal count, was found in the spleens of rats given the native extract preparation; by contrast, however, no change was observed in splenic megakaryocyte numbers in rats given the NAse-treated extract. On the other hand, NAse-treated extract retained its ability to stimulate bone marrow megakaryocyte proliferation in the same rat. The urinary extract also revealed in vitro Meg-CSF activity with a specific activity of 31, 750 CFU-Meg colonies/mg of protein.

Anemia, Aplastic↗
PubMed1981

Subacute arsenic neuropathy: clinical and electrophysiological observations.

Two patients with subacute arsenic neuropathy are described and the results of serial conduction velocity determinations from the very early stages of the illness to partial recovery are reported. Sensory and motor deficits were maximal within four weeks of the estimated time of exposure. Recovery was slow, with only partial improvement of the neurological deficits two years after onset of the illness. Progressive slowing of motor conduction velocity was observed in the first three months followed by a gradual increase in velocity thereafter. The possible mechanisms underlying the temporal profile of the electrophysiological changes are considered. The need for initiating chelation therapy before the development of the neuropathy is emphasised.

Arsenic Poisoning↗