PubMed Health⌕ Search

Biomedical subjects

C Delfini

Publications and source records attributed to C Delfini.

At least 55 records · Page 3Linked to original sources
PubMed1985

Cell-cycle dependence and properties of the HeLa cell DNA polymerase system.

Analysis of the properties of the DNA polymerase (pol) system as a function of fundamental factors of the assay environment allowed a rather accurate estimation of its dependence on the HeLa cell cycle. For pol alpha, the temperature and pH optima were 38.1 degrees C and 8.0, respectively; for pol beta, these optima were 36.2 degrees C and pH 7.4. Pol gamma showed a pH optimum at 7.7. Optimum activity for both the alpha and beta enzymes was observed at 60 mM Tris. The maximal activity at 36.2 degrees C and pH 7.4 was associated with resistance to N-ethylmaleimide (MalNEt), whereas that at 38.1 degrees C and pH 8.0 was sensitive to MalNEt. Incorporation of [3H]dTTP was maximal after 1 hr of incubation for the former activity and after 4 hr, for the latter. In extracts from cells in early S phase, the pol activity decreased after 1 hr of incubation, was MalNEt-resistant, and was characterized by temperature and pH optima at 36.2 degrees C and 7.4, respectively. In extracts of late S-phase cells, the pol-catalyzed incorporation of [3H]dTTP continued after 4 hr of incubation, was MalNEt-sensitive, and was characterized by temperature and pH optima at 38.1 degrees C and 8.0, respectively. Thus, a pol beta-type activity appeared in early S phase, whereas a pol alpha-type activity appeared in late S. During the G1, M, and G2 phases, a background level of pol activity was observed that showed intermediate kinetic properties.

Cell Cycle↗
PubMed1985

Bone marrow donors other than HLA genotypically identical siblings for patients with thalassemia.

This report describes the successful bone marrow transplantation of three children with thalassemia who received bone marrow, one from an HLA identical but mixed lymphocyte culture-reactive sibling, the other two from an HLA phenotypically identical parent. Evidence of engraftment was detected early (19-21 days) in all three children and only grade II acute GvHD was observed in one patient. Our report indicates that thalassemic patients can be cured by bone marrow transplantation from selected donors other than HLA genotypically identical siblings.

Bone Marrow↗
PubMed1985

[Brain of the cod (Gadus morhua morhua, Linné 1758) (Pisces, Paracanthopterygii). Qualitative and quantitative analysis of major subdivisions].

The Cod, Gadus morhua, is a North Atlantic fish of the family Gadidae which occurs at depths of 80 to 600 m (usually 150 to 200 m). It often occurs in shoals and tends to be migratory. It has a typical teleost brain except for the gadid feature of long olfactory tracts. Gadid fishes have a low level of encephalization (RIDET, 1982). The index of encephalization of the Cod is near the mean for the family. This index changes with season due to the change in body weight; it is lowest during the spawning season (which takes place in spring). Five subspecies of Gadus morhua are recognized. A comparison was made of the index of encephalization of the subspecies which is restricted to the White Sea, Gadus morhua maris albi, Derjugin 1920 and Gadus m. morhua, Linné 1758. The index of the White Sea form was significantly higher, thus supporting its recognition as subspecies. A volumetric analysis was made of the subdivisions of the Cod brain. It was found to have a large cerebellum, large medulla oblongata and a tendency to macrosmy, but a small telencephalon and tectum opticum (tendency to micropty). This is what would be expected from the environment and habits of this fish.

Animals↗
PubMed1984

Allogeneic marrow transplantation for thalassemia.

Thirteen patients with homozygous beta thalassemia underwent allogeneic marrow transplantation from sibling donors, 12 of whom were heterozygous for beta thalassemia. Six patients were transplanted in an advanced stage of their disease while seven were transplanted early in their disease course. Donors and recipients were genotypically identical for the HLA-A, -B and -D loci in 11 cases and mismatched for the D locus in two. A variety of preparative regimens was utilized involving high doses of busulphan (Bu) and/or cyclophosphamide (CY) and/or total body irradiation (TBI). Failure of engraftment or autologous hematologic recovery after transient engraftment was seen after intensive preparative regimens including: CY 200 mg/kg and 800 rad of TBI; Bu 8 mg/kg and CY 200 mg/kg; and Bu 8 mg/kg, CY 200 mg/kg, and 300 rad of TBI. A regimen of Bu 16 mg/kg, CY 200 mg/kg, and 400 rad of TBI resulted in deaths from transplant-related causes in the three patients treated with this regimen. Seven of the 13 patients are surviving 363-665 days after transplant. Five of the seven failed to achieve engraftment or had autologous reconstitution after transient engraftment. Five of the six deaths were transplant related, and one patient died of cardiac failure one year after an unsuccessful transplant attempt. Two patients are surviving with engraftment and without thalassemia major 363 and 491 days after transplantation. Both of these patients were transplanted early in their disease course.

Adolescent↗
PubMed1983

Ontogeny of granulocyte-macrophage progenitor cells in the human fetus.

The CFU-Gm content of liver, spleen and bone marrow of human fetuses was determined from the 8th to 28th week of gestational age. The study of progenitor cells from 43 fetal livers revealed that the CFU-Gm increased from 8 to 12 weeks, was relatively stable through 16 weeks and thereafter declined by 22 to 24 weeks. The total number of liver CFU-Gm rose from 10(4) to greater than 10(6) CFU-Gm by the 16th week of gestation and declined to approximately 4 X 10(5) progenitor cells by 22 to 24 weeks. Peak values of bone marrow CFU-Gm were noted at 10 to 14 weeks of gestation. Generally, the numbers of these progenitor cells declined by 16 to 18 weeks; however, several high values were obtained at later times. Splenic CFU-Gm were relatively constant in number between 12 and 28 weeks of gestation with no correlation with fetal age. Thus, these studies indicate that certain fetal tissues contain substantial numbers of hemopoietic progenitor cells. Based on the quantity of CFU-Gm obtained, it appears feasible to use fetal liver cells as a source of progenitor cells for transplantation.

Bone Marrow↗
PubMed1983

Fetal haemoglobin synthesis following fetal liver transplantation in man.

Transplantation of haematopoietic tissue from the fetus to the adult is of considerable clinical and theoretical interest. In particular it could help to understand whether the haemoglobin switch is under the influence of environmental factors or inherently programmed in the haemopoietic cell population. In the present study we have monitored haemoglobin synthesis following fetal liver transplantation (FLT) in a patient with acute leukaemia after intensive chemoradiotherapy. 28 days following FLT, the haemoglobin synthesis showed a predominantly fetal haemoglobin pattern, as determined by globin chain synthesis of bone marrow cells and by the peroxidase anti-peroxidase (PAP) method applied to bone marrow sections treated with anti-fetal haemoglobin antibodies. These findings demonstrate that, in man, fetal haemopoietic cells, transplanted into an adult environment, do not immediately switch to the production of adult haemoglobin.

Bone Marrow↗
PubMed1982

Biosynthesis and characterization of [15N]actinomycin D and conformational analysis by nitrogen-15 nuclear magnetic resonance.

We describe the production and characterization of actinomycin D labeled with 15N at all twelve nitrogen positions. Cultures of Streptomyces parvulus were incubated in the presence of racemic [15N]glutamic acid and, following an initial delay, labeled antibiotic was produced. Evidence is presented that the D enantiomorph of glutamic acid was ultimately used for actinomycin biosynthesis. The 15N NMR spectrum at 10.14 and 20.47 MHz of the labeled drug in CDCl3 is presented. All nitrogens except the phenoxazone chromophore nitrogen are inverted when spectra are obtained under broad-band proton irradiation conditions. All 15N resonances have been assigned, and the proton-nitrogen one-bond coupling constants were determined in CDCl3 to be 92.5 +/- 0.3 Hz for the valine and threonine amide protons by both 1H and 15N NMR. 15N NMR spectra were also obtained in dimethyl sulfoxide, methanol, and water in order to probe solvent interactions with the peptide nitrogens and carbonyl groups. Large downfield shifts (greater than 5 ppm) were seen for the Pro, sarcosine, and methylvaline resonances when the solvent was changed from dimethyl sulfoxide to water. Smaller downfield shifts were observed for the Val and Thr peaks. These results are discussed in terms of a model for the solution conformation of the actinomycin pentapeptide rings based on different hydrogen-bonding interactions in the monomer in organic solvents and the dimer which is formed in water.

Dactinomycin↗
PubMed1982

Cholera toxin B-subunit protects mammalian cells from ricin and abrin toxicity.

The glycoproteins ricin and abrin intoxicate cells by inhibiting protein synthesis. Pretreatment of HeLa cells with cholera toxin partially protects them from ricin and abrin activity. The involvement in this phenomenon of the various effects of cholera toxin, namely, redistribution of membrane receptors elicited from protomer B and increasing cyclic AMP concentrations induced by protomer A, were studied. Substances able to enhance cyclic AMP concentrations do not affect ricin and abrin activity, while protomer B alone protects cells. In addition, the effects of several lectins on ricin or abrin toxicity were examined. Almost complete prevention of ricin or abrin activity was obtained using concanavalin A (Con A) and wheat germ agglutinin (WGA). Conversely, neither succinyl Con A nor Ulex europeus agglutinin (UEA) affected the cellular response. Both protomer B of cholera toxin and Con A did not alter the binding of ricin or abrin; they seem to protect cells by altering membrane structure.

Abrin↗
PubMed1982

Fetal liver transplantation in 2 patients with acute leukaemia after total body irradiation.

2 patients with acute leukaemia in relapse were transplanted with fetal liver cells following a conditioning regimen of cyclophosphamide (120 mg/kg) and total body irradiation (1000 r). Each patient achieved a remission with haematopoietic recovery that was rapid in one case and delayed in the other. In one case there was evidence of chimerism as demonstrated by the presence of the XYY karyotype of the donor fetus in 20% of marrow metaphases, by the presence of double Y bodies in the peripheral blood, by the appearance of new HLA-antigens, and by red cell isoenzyme phenotypes of donor origin. In the second case there was prompt haematopoietic recovery and the appearance of red cell isoenzyme phenotype of donor origin. Survival was 153 and 30 d, respectively, and both patients died of interstitial pneumonia without evidence of graft versus host disease.

Acute Disease↗
PubMed1982

Novel antibiotic resistance transfer in Bacteroides.

Resistance to tetracycline and lincosamide antibiotics was transferred en bloc from a strain of Bacteroides fragilis (V503) to a plasmidless strain of Bacteroides uniformis (V528) during in vitro filter matings. Resistance transfer was detected at frequencies of 10(-5) to 10(-6) drug-resistant progeny per input donor cell and was dependent on cell-to-cell contact of donors and recipients. Transfer was insensitive to DNase and was not mediated by chloroform- or filter-sterilized donor broth cultures. A determinant for resistance to cefoxitin in V503 was not transferred in this system. V503 contained a 3.7 x 10(6)-dalton plasmid (pVA503). Drug-resistant progeny of V503 x V528 matings usually contained pVA503, but up to 20% of the total progeny of such crosses were plasmid free. Filter blot DNA hybridization studies (Southern method) confirmed that pVA503 was not integrated into the host chromosome of the plasmidless progeny. Drug-resistant progeny from V503 x V528 matings (with or without pVA503) conjugally transferred clindamycin resistance an tetracycline resistance to a suitable recipient strain. None of the drug resistance determinants of V503 were affected by treatment with standard plasmid curing regimens, and methods designed to detect very large plasmid molecules failed to suggest the involvement of extrachromosomal DNA in this resistance transfer system. The well-characterized Bacteroides R plasmid, pBF4 (conferring clindamycin resistance), was found to share hybridizing sequences with bulk cellular V503 DNA when examined by filter blot hybridization. Similarly sized sequences were found in drug-resistant progeny recovered from matings. Neither of the two pBF4 derivatives carrying deletions that abolished clindamycin resistance hybridized with V503 DNA.

Anti-Bacterial Agents↗