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L Bertolini

Publications and source records attributed to L Bertolini.

At least 37 records · Page 2Linked to original sources
PubMed1991

Parametric method for the detection of inter- and intrasweep variability in VEP processing.

The paper introduces a Kalman filter procedure for the processing of single-sweep visual evoked potentials (VEPs). The identification of the filter coefficients is based on a model of signal and noise interaction which considers the generating process as the superposition of the true evoked response to an AR process (the background EEG) and a broader spectrum noise. Intersweep variability is thus evident on the filtered response and a functional parameter of the filter (VP(t), namely variability path) is proposed for the automatic determination of the latencies associated with the main peaks of the response. Finally, the time-variant algorithm allows the quantification of the intrasweep variability for possible interpretation of the physiological mechanism involved.

Adult↗
PubMed1984

[Snake bite disease. Review of the literature].

The aetiology, the epidemiology and the pathogenesis of poisoning by viper bites in Italy are outlined. The symptomatology and therapy are also described, and it is noted that antivenom must be reserved for some selected cases.

Adolescent↗
PubMed1984

Growth factors that stimulate human granulocyte-macrophage colony formation produced by the cell line CM-S.

CM-S is an autonomous cell line of human hemopoietic precursor cells inducible to monocyte-macrophage differentiation in response to appropriate inducing agents. CM-S cells produce factors that stimulate their own growth and proliferation, and are also capable of stimulating clonal proliferation of human, but not mouse, monocytic and granulocytic bone marrow progenitor cells in viscous medium. Preliminary purification steps have demonstrated at least two species, one of which (MW 30,000-50,000) retains both these activities, while the other (MW less than or equal to 10,000) apparently retains only the autostimulatory activity. CM-S cells could thus be a useful source for the purification of human colony stimulating factors (CSFs). CM-S cells also respond to factors present in human placenta conditioned medium, known to contain human CSF. This suggests that CM-S cells could provide a homogeneous target cell population for testing CSFs from other human sources.

Animals↗
PubMed1981

Lack of correlation between in vivo and in vitro assays for the detection of virus released from clones of Friend erythroleukemia cells.

The biological properties of the virus synthesized by 18 clones of a line of mouse bone-marrow hematopoietic cells transformed in vitro by the polycythemic strain of Friend leukemia virus (FLV-P) were compared. In vitro assays were performed to determine whether the virus released into the culture fluids was ecotropic or xenotropic, and in vivo assays were carried out to determine spleen focus formation and leukemogenicity in susceptible DBA/2J and BALB/c mice. A number of clones released virus which reproduced the entire range of effects typical of the FLY-P complex. However, in other clones, there appeared to be no correlation between the assays for leukemogenicity and the assays for either ecotropic virus, reverse transcriptase activity, or virus antigens. Xenotropic virus was not detected in any of the cultures. These results suggest that the FLV-P complex contains a heterogeneous population of viruses, but the possibility that the differences observed may be due to the inability of FLV-P to be expressed fully in some clones cannot be excluded.

Animals↗
PubMed1981

Variations in the response of cloned murine friend erythroleukemia cells to different inducers.

Cells of the line 3BM-78 derived from murine bone marrow cells infected in vitro with polycythemic Friend leukemia virus (FLV-P) produce virus with spleen focus-forming activity (SFFV) and can be induced to synthesize hemoglobin. Fifteen clones, isolated from this line, have been analyzed in detail for the effect of different inducing agents (dimethyl-sulfoxide, DMSO; hexamethylene bisacetamide, HMBA; and sodium butyrate, SB) on the synthesis of hemoglobin and virus at the clonal level. All the clones proved to be inducible with one or more of the agents, but the degree of the response depended on the type and concentration of the agent used. In general, the effectiveness of the agent--within the usual range of concentration for induction--both for hemoglobin and for virus synthesis, was in the order HMBA greater than DMSO greater than SB. Reverse transcriptase activity was, however, more easily induced than hemoglobin synthesis in that stimulation was seen at lower concentrations of the same inducing agent. This clonal analysis confirmed that virus and hemoglobin production are regulated independently in these erythroleukemic cells chronically infected with FLV-P.

Acetamides↗
PubMed1980

Cytochemical characteristics of leukopoietic differentiation in murine erythroleukemic (Friend) cells.

The 3BM-78 murine Friend erythroleukemia cell line was obtained by in vitro transformation of bone marrow cells of DBA/2J mice by the polycythemic Friend virus complex. Thirty-five subclones have been isolated and tested for their ability to express various markers of blood and bone marrow cells. Upon dimethyl sulfoxide treatment, the cells differentiated along the erythroid pathway as shown by morphological evidence and by their increased synthesis of hemoglobin and spectrin. In addition, a high proportion of dimethyl sulfoxide-induced cells stained positive for specific esterase, a marker characteristic of granulocytic cells. Of these cells, about 20% stained positive for both hemoglobin-peroxidase and specific esterase. Analysis of the subclones showed that the expression of these markers for erythroid and leukopoietic differentiation was uncoordinated. Further dissection of expression was obtained by the use of two potent tumor promoters, 12-O-tetradecanoylphorbol-13-acetate and phorbol-12,13-benzoate, which in general inhibited specific esterase more than hemoglobin peroxidase expression. Inhibition was related to the structure of the phorbol diester and was unrelated to toxicity. No evidence was found for other markers characteristic of different pathways of differentiation, such as Fc and C3 receptors, cell surface immunoglobulins, theta antigen, or the capacity to phagocytose inert particles. All cells stained positive for nonspecific esterase activity in both the presence and the absence of dimethyl sulfoxide. This staining was only partially fluoride sensitive. In unstimulated cultures, a few cells also reacted for myeloperoxidase, Sudan black staining and, very rarely, alkaline phosphatase staining. These findings support the view that 3BM-78 cells are leukemic cells which, despite a prevalent commitment to erythroid differentiation, retain the genetic determinants for some traits of leukopoietic differentiation. These traits may be expressed under suitable culture conditions.

Acetates↗
PubMed1979

In vitro transformation of mouse bone marrow cells by the polycythemic strain of Friend leukemia virus.

Strains of Friend leukemia virus (FLV) that are associated with polycythemia contain the defective spleen focus-forming virus (SFFV). To determine whether the transforming ability of FLV was affected by the presence of this second agent, DBA/2J mouse bone marrow cells were infected in vitro. Criteria for transformation were the establishment of permanent lines, growth on semisolid agarose, and the production of tumors at the site of inoculation in syngeneic hosts. Two lines of immature hematopoietic cells that grow in suspension originated from the infected cultures. Each has an almost diploid karyotype (38-39 chromosomes) and 3-4 metacentric chromosomes. These transformed cells express gp71 viral envelope glycoprotein and p30 viral core protein antigens. Virus production was measured by reverse transcriptase (RNA-dependent DNA polymerase) activity of the virions released into the medium. The virus, assayed in vivo for infectivity, has SFFV activity but is attenuated for leukemogenicity. The stimulation of hemoglobin synthesis in the cells grown in medium supplemented with dimethyl sulfoxide or hexamethylene bisacetamide indicates that the cells are erythroid in origin. SFFV may have a function analogous to erythropoietin in influencing the process of transformation by FLV.

Animals↗
PubMed1978

Antibody formation and transient immune complex glomerulopathy in A-strain mice with C1300 neuroblastoma tumors.

One to three-month-old A-strain mice, inoculated subcutaneously with 2 x 10(6) viable syngeneic C1300 neuroblastoma cells (clone NB9R) developed a palpable tumor within 9-12 days and died within 28-30 days. A transient glomerulopathy developed after 16-24 days. Despite a normal histologic appearance, the nephropathy was clearly demonstrated by electron microscopy and was classified as a focal mesangiopathic glomerulonephritis. Deposits of host 7S-G immunoglobulins and C3 complement fragments were detected in these same kidneys by immunofluorescence. Radioimmunoprecipitin determinations on sera obtained from mice at different intervals from tumor cell inoculation, revealed that untreated mice contained circulating antibodies capable of reacting with 125I-labeled gp69-71 glycoprotein from Gross murine leukemia virus (MuLV). Antibodies to p30 MuLV antigen and to crude membrane antigen (s) (CMA) solubilized from NB9R cells were found in sera only after tumor cell inoculation. Circulating immune complexes formed by host 7S-G immunoglobulins were clearly detected from day 16 to 22. Antibodies eluted from kidneys with nephropathy were shown to react with NB9R cells in vitro and to react specifically with CMA and the p30 MuLV antigen.

Animals↗
PubMed1976

Differences between murine C1300 neuroblastoma clones detected by rosette formation with nerve growth factor-coated sheep red blood cells.

The expression of receptors for nerve growth factor (NGF) on the cell surface was assayed by rosette formation with ligand-coated sheep red blood cells (SRBC). Cell clones derived from the murine C1300 neuroblastoma and from hybrids between a neuroblastoma clone and L cell clones showed a wide variation in the capacity to form rosettes with NGF-coated SRBC. All the neuroblastoma, L cell and hybrid clones formed rosettes with phytohemagglutinin-coated SRBC and none formed rosettes with cytochrome c- or ferritin-coated SRBC or with SRBC not coated with ligand.

Animals↗
PubMed1976

In vitro stimulation of mouse lymphoid cells by C1300 neuroblastoma cells or tumor membrane extracts.

Spleen lymphoid cells from A/J mice recognize specific antigenic differences on the surface membranes of syngeneic C1300 neuroblastoma cells and incorporate 3H-thymidine into DNA in unidirectional mixed cell cultures in the absence of isologous serum. The response requires an optimal ratio of responder to stimulator cells, and is detectable after 24 h. It is specifically blocked by the presence of a papain-solubilized crude membrane extract from the same neuroblastoma cells, the extent of inhibition being dependent on the concentration of the extract and the time when it is added to the cultures. Spleen cells from mice bearing the neuroblastoma respond earlier and incorporate more 3H-thymidine than cells from unsensitized mice. The enhanced response of the primed spleen cells to the stimulator cells is similar to a secondary immune response and can be induced by soluble crude tumor extracts in the absence of stimulator cells.

Animals↗