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Biomedical subjects

M Lopez

Publications and source records attributed to M Lopez.

At least 199 records · Page 11Linked to original sources
PubMed1994

Autologous bone marrow transplantation in ALL: relapse linked to infusion of tumor cells with the back-up marrow.

A 41-year-old female patient with a pre-B ALL expressing 2 BCR/ABL transcripts e1/a2 and b2/a2 underwent autologous bone marrow transplantation (aBMT) with marrow grown in long-term culture (LTC) for consolidation of remission (CR). After failing to engraft on day 54 she received her back-up marrow. She engrafted by day 23 and developed a full-blown leukemic relapse 2 weeks later. She died from tumor progression 3 months after infusion of the backup marrow. Analysis of the BCR/ABL transcripts weakly positive at time of collection of the backup marrow, negative in the LTC marrow and in the patient after infusion of the LTC marrow, again positive from day 29 after infusion of the backup marrow until death, strongly suggests that infusion of residual tumor cells with the backup marrow contributed to the relapse.

Adult↗
PubMed1994

Characterization of spontaneous factor-independent cell lines derived from the human leukemic cell line TF-1: a dominant event.

Uncontrolled proliferation of acute myeloid leukemia (AML) cells is an important step during leukemogenesis. However, little is known about the mechanisms leading to growth autonomy. Studies using immortalized murine hematopoietic cell lines have suggested that autocrine production of growth factors, or the constitutive activation of molecules in growth factor signalling pathways, are involved. We have established six spontaneous factor-independent cell lines from the human growth factor-dependent TF-1 cell line. The factor-independent cells showed no detectable growth factor activity. Immunoblotting analyses of tyrosine phosphorylation, Raf-1 and extracellular signal-regulated kinase 2 (ERK-2) showed a similar pattern in all the cell lines including TF-1 cells. Furthermore, somatic-cell hybrids between TF-1 and the factor-independent cells grew in absence of growth factor. Taken together this data demonstrates that the factor independence in this system is dominant and suggests that the molecular event is located either downstream of the Raf-1 and MAP kinases pathway or on an alternative pathway. Finally, the karyotype analysis of one factor-independent cell line TF-1i1 and TF-1H- (G418 resistant, HAT sensitive TF-1 cells) and their hybrids demonstrated an unstable derivative chromosome [der(19) t(19;?) (q13.1;?)] which seemed to correlate with the factor-independence capacity. This model may help in our understanding of autonomous proliferation by human myeloid leukemias.

Acute Disease↗
PubMed1994

[Microbiological safety and endothelial quality control during preservation of corneal grafts at +31 degree C].

Over a 10-month-period, 59 corneas were organ-cultured at + 31 degrees C and 7 were preserved at + 4 degrees C. Among the 59 organ-cultured corneas, 41% (24) were grafted and 25% (15) developed an infection during preservation. At the time of surgery, preservation medium and scleral rim were tested for microbiology. Infection during preservation was bacterial (80%, 12/15) and fungal (20%, 3/12). Scleral rims were sterile in 96% (24/25) of the grafted corneas preserved at + 31 degrees C but 34% (2/6) at + 4 degrees C (p < 0.01). Preservation media were sterile in 100% (24/24) of organ-cultures at + 31 degrees C but in 83% cases (5/6) of preservations at + 4 degrees C (NS). The percentage of endothelial dead cells increased with postmortem enucleation delay (r = 0.43; p = 0.03). The average endothelial cell loss during organ-culture was 11.2% (+/- 10.4). It correlated with endothelial density (r = 0.42; p = 0.04) and with percentage of endothelial dead cells (r = 0.43; p = 0.04) after enucleation. Organ-cultured at + 31 degrees C was able to assess graft sterility in almost 100% of the cases but corneas are lost due to infection. Graft sterility is not usually possible with preservation at + 4 degrees C.

Aged↗
PubMed1993

[Positive selection of hematopoietic CD 34 stem cells for autograft].

The CD 34 antigen is a glycoprotein found on the surface of hematopoietic stem cells and early committed progenitors. The CE 34 stem cells from 14 samples of bone marrow, cord blood or leucapheresis were isolated using a positive selection procedure involving an anti CD 34 biotinylated monoclonal antibody and an avidin immunoabsorption device. Results showed that in 60 percent of samples, the positively-selected fractions contained more than 70 percent CD 34 cells. Concentration in CFU-GM and BFU-E progenitors increased 15 and 26 fold respectively in the CE 34 enriched samples. Long-term culture of two samples demonstrated that nearly all of the most immature progenitors were recovered in the procedure. These preliminary results showed that the positive selection technique of CD 34 hematopoietic stem cells is now available for use in autologous or allogeneic hematopoietic stem cell transplantation.

Antigens, CD↗
PubMed1993

Efficient adenovirus-mediated gene transfer into human blood monocyte-derived macrophages.

The efficiency of gene transfer into human blood monocyte-derived macrophages has been evaluated using a replication-defective adenovirus vector harboring a lac Z gene of E. coli as a reporter gene. Whereas, no beta-galactosidase activity was found in freshly infected purified monocytes, 40% to 80% of infected macrophages which derived from these monocytes showed a beta-galactosidase activity, 2 to 4 days after infection and lasted for at least 3 weeks. Moreover, beta-galactosidase activity was found in infected monocyte/macrophages 7 days after their injection into a human tumor preestablished in nude mice. These data indicate that it is possible to transfer and stably express a gene of potential therapeutical function into human monocyte-derived macrophages using an adenovirus vector.

Adenoviridae↗
PubMed1993

Novel method for the measurement of cytokine production by a one-stage procedure.

A new one-step culture-immunoassay procedure is described for testing cytokine production by immunocompetent cells in whole blood (WB) without the need for an isolation step. Briefly, WB samples or distilled water were added to RPMI medium containing specific anti-cytokine peroxidase-labelled monoclonal antibodies and incubated in micro-well plates coated with specific capture monoclonal antibodies, directed against distinct epitopes of the cytokine, and containing dried polyclonal activators (5.625 micrograms LPS + 1.125 micrograms PHA) or dried standards respectively. The optimalisation of the assay is described for an extended measurement range. The best compromise between sensitivity and linearity was obtained with the addition of 50 ng/well for TNF-alpha and IL-6 or 100 ng/well for IFN-gamma of unconjugate antibodies to the corresponding conjugate. The kinetics of individual production of each cytokine in WB of normal healthy donors showed values entering the standard range following incubation times of between 2 and 8 h for TNF-alpha, 2 and 4 h for IL-6, and 4 and 24 h for IFN-gamma. The sensitivity, the precision (intra-assay CVs) and the reproducibility (interassay CVs) of the assays were as follows: 70 pg/ml, < or = 14% and < or = 11% for TNF-alpha; 25 pg/ml, < or = 11% and < or = 16% for IL-6; 25 pg/ml, < or = 19% and < or = 20% for IFN-gamma. The accuracy (% of recovery) of the assays was in the order of 100% and between 40 and 60% in the absence or presence of polyclonal activators, reflecting the occurrence of an active production/consumption mechanism during the activation.

Adult↗
PubMed1993

Combined treatment with buserelin and cyproterone acetate in metastatic male breast cancer.

BACKGROUND: Male breast cancer (MBC) is considered an androgen-dependent tumor, and as in prostatic cancer, responses have been reported with use of antiandrogens or gonadotropin-releasing hormone analogs. Thus, it is reasonable to postulate that better results could be achieved by combining these two agents. METHODS: Eleven men with recurrent or progressive carcinoma of the breast have been treated with buserelin 1500 micrograms subcutaneously daily in the first week and 600 micrograms daily subsequently and cyproterone acetate (CPA) 100 mg twice a day orally starting 24 hours before the first dose of buserelin. RESULTS: Objective responses have been observed in seven patients with a median duration of 11.5 months (range, 9-24+ months). Responses were not correlated to the dominant site of disease. Three patients had stable disease lasting 5 months. Median survival was 18.5 months. Side effects primarily were decrease or loss of libido, impotence, and hot flushes. CONCLUSIONS: Total androgen blockade with buserelin and CPA seems effective in the treatment of patients with advanced cancer of the male breast, but its superiority over standard androgen suppression remains to be demonstrated.

Aged↗
PubMed1993

Interaction of VIP, PACAP and related peptides in normal and leukemic human monocytes and macrophages.

The activation of the cAMP signaling pathway by vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP) and related peptides was studied (i) in normal peripheral human monocytes and THP-1 leukemic human monocytes, (ii) in their derived macrophage counterparts respectively obtained after spontaneous differentiation or retinoic acid (RA) treatment, and (iii) in human bronchoalveolar macrophages. In THP-1 monocytes, PACAP increased basal adenylate cyclase activity 5.3-fold, with an affinity 50-times greater than that of VIP or helodermin (Ka = 3.2 x 10(-11) M VIP), whereas in normal peripheral monocytes, PACAP and VIP exhibited similar affinities and only increased cAMP generation 2-fold (EC50 = 10(-9) M). Spontaneous and RA-induced differentiation into normal and leukemic macrophages induced a progressive loss of cAMP production and regulation of superoxide anion production by VIP and related peptides. The neoplastic transformation in THP-1 monocytes and the deficiencies in the cAMP cascade observed during the terminal differentiation of normal and leukemic human macrophages may relate to a differential genetic expression of the VIP/PACAP receptor subtypes, and alterations in the functional activity of the stimulatory and inhibitory Gs/Gi subunits of adenylate cyclase.

Adenylyl Cyclases↗
PubMed1993

Autologous lymphocytes prevent the death of monocytes in culture and promote, as do GM-CSF, IL-3 and M-CSF, their differentiation into macrophages.

Blood monocytes collected by apheresis from healthy donors were differentiated in vitro to macrophages which were subsequently activated with recombinant human interferon-gamma. 7 day cultures were established by seeding Ficoll-separated mononuclear cells or elutriation-purified monocytes under different culture conditions. The best macrophage yields required the seeding of mononuclear cells (instead of purified monocytes) in teflon bags with a high air-liquid surface interface. The effects of GM-CSF, IL-3 and M-CSF on the macrophage yield were then evaluated. GM-CSF increased the average yield by 3.6- and 2.3-fold when purified monocytes or total mononuclear cells were seeded respectively. The corresponding increases with IL-3 were 2.5- and 2.1-fold respectively and with M-CSF 1.2- and 1.4-fold respectively. Macrophages matured under these various conditions displayed similar CD14, CD64, CD71, HLA-DR and Max 1 antigen expression and similar in vitro anti-tumoral activity against U937 cells. Culturing in the presence of cytokines permits the large scale production of activated macrophages for adoptive immunotherapy trials.

CD3 Complex↗
PubMed1993

Angiotensin I-converting enzyme in human circulating mononuclear cells: genetic polymorphism of expression in T-lymphocytes.

The expression of angiotensin-I converting enzyme (ACE; EC 3.4.15.1) in human circulating mononuclear cells was studied. T-lymphocytes contained the highest level of enzyme, approx. 28 times more per cell than monocytes. No activity was detected in B-lymphocytes. ACE was present mainly in the microsomal fraction, where it was found to be the major membrane-bound bradykinin-inactivating enzyme. An mRNA for ACE was detected and characterized after reverse transcription and amplification by PCR in T-lymphocytes and several T-cell leukaemia cell lines. We have previously observed that the interindividual variability in the levels of ACE in plasma is, in part, genetically determined and influenced by an insertion/deletion polymorphism of the ACE gene. To investigate the mechanisms involved in the regulation of ACE biosynthesis, the ACE levels of T-lymphocytes from 35 healthy subjects having different ACE genotypes were studied. These levels varied widely between individuals but were highly reproducible and influenced by the polymorphism of the ACE gene. T-lymphocyte levels of ACE were significantly higher in subjects who were homozygote for the deletion than in the other subjects. These results show that ACE is expressed in T-lymphocytes and indicate that the level of ACE expression in cells synthesizing the enzyme is genetically determined.

Adult↗
PubMed1993

Regulation of CD2-mediated human T cell activation: anti-CD8 monoclonal antibodies inhibit CD2-mediated rise in intracellular calcium.

The human CD8 glycoprotein regulates the function of cytotoxic T cells activated by antigenic peptide as well as via CD3 or CD2 mAbs. Activation of T cells by CD2 mAbs requires two mAbs directed against distinct CD2 epitopes and induces tyrosine phosphorylation, PI-PLC activity generating the second messengers, IP3 and DAG, and finally lymphokine secretion. We have investigated the role of the CD8 alpha molecule in CD2-mediated activation of human cytotoxic T cell clones and CD8+ resting T cells. CD8 alpha-specific mAb inhibited 60% of the allospecific cytotoxicity of the CD8+ clone against its target cell and 86% of the CD2-redirected killing against the HLA Class I-negative Daudi target cell. In addition, CD8 alpha-specific mAb inhibited CD2-mediated TNF alpha and IL2 secretion by the CD8+ clone. Furthermore, CD8 alpha-specific mAb inhibited the increase in intracellular ionized calcium mediated by CD2 mAbs in the CD8+ clone and in purified T cells. Since the [Ca2+]i recruitment from internal stores induced by CD2 mAbs was inhibited, the inhibitory effect induced by the CD8 alpha-specific mAb probably acts on the PI-PLC activation pathway. This inhibition mechanism involves neither a decrease in affinity of CD2 mAb for its target nor a decrease in CD2 cell surface expression or a rise in cAMP known as an inhibitor of the CD2-mediated PI-PLC activity. These results suggest that the inhibitory mechanism induced by the CD8 mAb may prevent the activation of the PI-PLC activity, probably through the CD8 alpha-associated protein tyrosine kinase p56lck.

Antibodies, Monoclonal↗
PubMed1993

Arrhythmogenicity of antiarrhythmic drugs and intraventricular conduction disorders: possible aggravation by myocardial ischemia--study in the porcine in situ heart.

The effects of three antiarrhythmic drugs were investigated in anesthetized, open-chest pigs, in a left ventricular area, under pacing at a constant high rate (180 beats/min), in the absence and presence of ischemia. Ischemia was produced by transient complete occlusion of the left anterior descending coronary artery near its origin. In addition to the surface electrocardiogram, conduction time and monophasic action potential were recorded in the contractile fibers. In the absence of ischemia, intravenous flecainide and propafenone 2.5 mg/kg, and intravenous cibenzoline 2.0 mg/kg considerably lengthened conduction time (by 50-90%) but had no significant effect on the monophasic action potential duration. Consequently, the cited antiarrhythmic drugs enhance the prolongation of conduction time by 60% but do not limit the 30% shortening of the monophasic action potential caused by ischemia. Contrary to what was expected, they largely reduced the time to onset of the fibrillation due to ischemia from about 120 to 25 seconds. Thus, they manifested profibrillatory properties (more pronounced than those of other antiarrhythmic drugs of class I), which might be explained by their potent action on depolarization.

Animals↗
PubMed1993

Comparison of CT and MRI in the evaluation of therapeutic response in thoracic Hodgkin disease.

Current imaging modalities are accurate in establishing the diagnosis and extent of thoracic Hodgkin disease. After treatment, however, it is extremely difficult to differentiate potential residual active neoplastic disease from scar tissue, or identify early recurrence. We evaluated the contribution of MRI in the assessment of the response to treatment of thoracic Hodgkin disease in the assumption that scar formation would be characterized by low signal intensity in all pulse sequences, whereas active tumor should maintain a degree of high signal intensity on T2-weighted images. In 47 occasions (23 patients) both CT and MRI were able to identify correctly active disease, but had low specificity in confirming remission because of residual tissues masses. High signal intensity on T2-weighted MR images often persisted despite remission, probably because of edema, necrosis, granulation or other factors. MRI was somewhat more specific than CT and may be quite valuable to confirm remission in patients with residual masses that no longer appear hyperintense on T2 after treatment.

Adolescent↗
PubMed1993

Dystrophic bladder wall calcifications following intravesical BCG treatment for superficial transitional cell carcinoma of bladder.

Bacillus Calmette-Guerin has been established as one of the most active agents for the treatment of superficial transitional cell carcinoma of the bladder. Although complications do occur with this agent, they are usually transient and mild. Two cases are herein reported in which dystrophic calcification of the urinary bladder occurred following BCG therapy; one had a diffuse and severe complication. This complication can occur with other intravesical agents, and methods for management are reported.

Aged↗
PubMed1993

Anti-T11.1 and -T11.2 monoclonal antibodies play a different role in CD2-mediated signal transduction.

We comparatively evaluated (Ca2+)i mobilization after triggering with a stimulatory pair of CD2 (CD2.9, anti-T11.1 + CD2.1, anti-T11.2) or CD3 mAbs in the differentiated T-cell line Jurkat, using INDO-1 labeling and cytofluorimetry. The results obtained showed different (Ca2+)i mobilization kinetics following CD2 or CD3 stimulation (the former being slower than the latter), not due to different association kinetics of mAbs. In a nonreciprocal manner, however, preliminary interaction with CD2.1 (anti-T11.2) followed by CD2.9 (anti-T11.1) induces a rapid (Ca2+)i rise, similar to CD3 stimulation, as shown by preincubation experiments. There is no interference between CD2.9 and CD2.1 mAb binding. CD2.1 mAb by itself is unable to induce (Ca2+)i mobilization; in addition, preincubation with CD2.1 mAb did not modify the CD2, CD3, CD45, or CD28 immunoprecipitation patterns. Triggering of the epitope recognized by CD2.1 mAb may favor, possibly via conformational changes of CD2 molecule or (Ca2+)i-unrelated metabolic effect(s), optimal signal transduction.

Antibodies, Monoclonal↗
PubMed1993

Phase II study of continuous intravenous infusion of recombinant interleukin-2 in patients with advanced renal cell carcinoma.

BACKGROUND: The goal of this study was to evaluate the therapeutic efficacy and toxicity of recombinant interleukin-2 (rIL-2) administered by continuous intravenous (CIV) infusion to patients with metastatic renal cell cancer (RCC). PATIENTS AND METHODS: Thirty patients with RCC were given rIL-2 18 MIU/m2/d CIV. The schedule consisted of two induction cycles and four maintenance cycles with a 3-week rest period between cycles. Each induction cycle consisted of two infusion periods lasting 120 and 108 hours, respectively, separated by a 6-day rest period. Each maintenance cycle consisted of a 120-hour infusion period. RESULTS: Among 29 assessable patients, the objective response rate was 14% (95% confidence interval, 2% to 26%); one patient achieved a complete response, and 3 partial responses. Ten patients (34%) had stable disease (SD). Median survival was 11 months. Toxicity was generally manageable. Hypotension was universal, but required dose reduction in only 2 patients. Increase in serum creatinine levels was observed in 20 patients, and returned to normal in all but 4 patients after discontinuation of treatment. CONCLUSION: Results confirm the efficacy of rIL-2 in patients with RCC and the feasibility of the treatment in a normal oncology ward. However, responses are observed in a minority of patients, and treatment-related toxicity, as well as technical problems, may be troublesome to many patients.

Adult↗