Biomedical subjects

F Goncalves

Publications and source records attributed to F Goncalves.

17 recordsLinked to original sources

PubMed1998

Protein kinase C mediates the mitogenic action of thrombopoietin in c-Mpl-expressing UT-7 cells.

Protein kinase C (PKC) has been implicated in signal transduction events elicited by several hematopoietic growth factors. Thrombopoietin (TPO) is the major regulator of megakaryocytic lineage development, and its receptor, c-Mpl, transduces signals for the proliferation and differentiation of hematopoietic progenitors. In this study we have examined the effect of TPO on the subcellular distribution of PKC (a measure of enzyme activation) in a growth factor-dependent pluripotent hematopoietic cell line that was engineered to express the c-Mpl receptor (UT-7/mpl). In addition, we have assessed the significance of this activation for the induction of both mitogenesis and differentiation. Using a PKC translocation assay, TPO was found to stimulate a time- and dose-dependent increase in the total content of PKC activity present in the membrane fraction of UT-7/mpl cells (maximum increase = 2.3-fold above basal level after 15 minutes with 40 ng/mL TPO, EC50 = 7 ng/mL). Accordingly, a decrease of PKC content in the cytosolic fraction was observed. Immunoblot analysis using PKC isotype-specific antibodies showed that TPO treatment led to a marked increase of the Ca2+/diacylglycerol-sensitive PKC isoforms alpha and beta found in the membrane fraction. In contrast, the subcellular distribution of these isoforms did not change after treatment with granulocyte-macrophage colony-stimulating factor (GM-CSF). Exposure of UT-7/mpl cells to the selective PKC inhibitor GF109203X completely inhibited the PKC activity associated to the membrane fraction after TPO treatment, and blocked the mitogenic effect of TPO. In contrast, GF109203X had no effect on the TPO-induced expression of GpIIb, a megakaryocytic differentiation antigen. Downregulation of PKC isoforms alpha and beta to less than 25% of their initial level by treatment with phorbol 12,13-dibutyrate also abolished the TPO-induced mitogenic response, but had no significant effect when this response was induced by GM-CSF. Taken together, these findings suggest that (1) TPO stimulates the activation of PKC, (2) PKC activation mediates the mitogenic action of TPO, and (3) PKC activation is not required for TPO-induced expression of megakaryocytic surface markers.

Biological Transport↗

PubMed1998

Inhibition of erythroid differentiation and induction of megakaryocytic differentiation by thrombopoietin are regulated by two different mechanisms in TPO-dependent UT-7/c-mpl and TF-1/c-mpl cell lines.

Thrombopoietin (TPO) regulates megakaryocytic (MK) maturation and platelet production. Molecular and cellular mechanisms of the TPO-induced MK differentiation are not totally understood. In order to develop cellular models to study these mechanisms, we introduced c-mpl into UT-7 and TF-1 cells by means of a retroviral vector and compared the effects of TPO on these two cell lines. UT-7 and TF-1 cell lines are two factor-dependent leukemic cell lines with an erythroid and MK phenotype. They proliferate in response to IL-3, GM-CSF and EPO, but not to TPO. The erythroid differentiation of both cell lines can be markedly increased by EPO. Several UT-7/c-mpl and TF-1/c-mpl cell clones which express different levels of the c-mpl protein (Mpl) were obtained and all became TPO-dependent for their proliferation. The UT-7/c-mpl clones, but not the TF-1/c-mpl clones, were capable of undergoing MK differentiation in response to TPO. This was demonstrated by the increase in MK markers (GPIIb, GPIIIa, GPIb alpha, GPIX and vWF), the appearance of cytoplasmic alpha-granules, intracellular membranes resembling demarcation membranes which were immunologically labeled with an GPIIb/IIIa anti-antibody, and a small percentage of polyploid cells (8N and 16N). In contrast, TPO inhibited the erythroid program of differentiation (glycophorin A, beta-globin and EPO receptor) as well as the differentiative activity of EPO in both UT-7/c-mpl and TF-1/c-mpl clones. It is noteworthy that the differentiative effect of EPO in TF-1/c-mpl cells was associated with an increase in GATA-1 transcripts which was totally suppressed by TPO. Overall the effects of TPO are the same as those of phorbol myristate acetate (PMA) which also induces MK differentiation and inhibits erythroid differentiation. These results suggest that: (1) Mpl expression is necessary but not sufficient for induction of MK differentiation; and (2) induction of Mk differentiation and inhibition of erythroid differentiation by TPO involve different signaling pathways; the pathway involved in the inhibition of erythroid differentiation might be related to a downregulation of GATA-1 expression in TF-1 cells.

Anti-Bacterial Agents↗

PubMed1998

Prognostic factors in clinical stage I nonseminomatous germ cell testicular tumors: rationale for different risk-adapted treatment.

OBJECTIVE: Surveillance after orchiectomy alone becomes popular for the management of clinical stage I nonseminomatous germ cell testicular tumours (CS I NSGCTT). Effort to identify patients at high risk of relapse leads to searching prognostic factors of CS I NSGCTT. The aim of this study was to identify those patients in whom a surveillance policy is less likely to be successful. PATIENTS AND RESULTS: Seventy-two CS I NSGCTT patients were stratified to different risk-adapted therapeutic approaches according to histopathologic findings of primary tumor removed by inguinal orchiectomy. Eighteen patients (group A) with vascular invasion and majority of embryonal carcinoma component in the primary tumor were treated with adjuvant BEP chemotherapy. None of them experienced disease progression after a median follow-up period of 36 months after orchiectomy. Five patients (group B) with vascular invasion and the majority of teratomatous elements in the primary tumor have been followed up 56 months after orchiectomy. They were treated with primary retroperitoneal lymph node dissection (RPLND). Two of them (40%) had pathologic stage II after RPLND and underwent subsequent chemotherapy. One of them died due to disease progression 29 months following orchiectomy. Another one lives with no evidence of disease (NED). Three patients in pathologic stage I are alive with NED. Forth-nine patients (group C) without vascular invasion have been followed up for a median duration of 37 months after orchiectomy. They were kept under close surveillance, consisted of regular follow-up with tumor markers, chest x-ray and CT of the retroperitoneum. Disease progression was observed in 7 (14.3%) patients after a median duration of 8 months after orchiectomy. They were treated with BEP chemotherapy and live with disease-free median survival of 22 months after completion of therapy. The overall survival rate of all 72 patients was 98.6%. The median survival for all patients was 37 months (range 7-73). CONCLUSIONS: The authors will continue to use surveillance policy only in patients without vascular invasion in the primary tumor.

Adolescent↗

PubMed1997

Thrombopoietin does not induce lineage-restricted commitment of Mpl-R expressing pluripotent progenitors but permits their complete erythroid and megakaryocytic differentiation.

In this study, we examined the in vitro and in vivo effects of forced expression of Mpl-R (the thrombopoietin receptor) on the progeny of murine hematopoietic stem cells. Bone marrow cells from 5-FU-treated mice were transduced with retroviral vectors containing the human Mpl-R cDNA, or the neomycine gene as a control. After 7 days cocultivation on virus-producer cells, GpE86-Mpl-R or Gp86-Neo, the types of hematopoietic progenitor cells responding to thrombopoietin (TPO) were studied by clonogenic assays. Mpl-R-infected cells gave rise to CFU-GEMM, BFU-E, CFU-MK, but not CFU-GM while Neo-infected cells produced only megakaryocytic colonies. In addition, when nonadherent cells from GpE86-Mpl-R cocultures were grown with TPO as the only stimulus for 7 days, a marked expansion of CFU-GEMM, BFU-E, and CFU-MK was observed, while no change in CFU-GM number was seen. Erythroid and megakaryocytic maturation occurred in the presence of TPO while a block in granulocytic differentiation was observed at the myeloblast stage. The direct effects of TPO on Mpl-R-transduced progenitor cells were demonstrated by single cell cloning experiments. To analyze the effects of the constitutive expression of Mpl-R on the determination of multipotent progenitors (CFU-S) and long-term repopulating stem cells, Mpl-R- or Neo-infected cells were injected into lethally irradiated recipient mice. No difference was seen in (1) the number of committed progenitor cells contained in individual CFU-S12 whether colonies arose from noninfected or Mpl-R-infected CFU-S; (2) the mean numbers of progenitor cells per leg or spleen of mice reconstituted with Mpl-R- or Neo-infected cells, 1 or 7 months after the graft; and (3) the blood parameters of the two groups of animals, with the exception of a 50% reduction in circulating platelet counts after 7 months in mice repopulated with Mpl-R-infected bone marrow cells. These results indicate that retrovirus-mediated expression of Mpl-R in murine stem cells does not modify their ability to reconstitute all myeloid lineages of differentiation and does not result in a preferential commitment toward the megakaryocytic lineage.

Animals↗

PubMed1997

Adrenal incidentalomas--analysis of 23 cases discovered by ultrasound.

Frequent use of abdominal ultrasonography (USG) increases discovery of incidental adrenal tumors. Our experience and concise review of recent opinions on management of adrenal incidentalomas is presented. In four out of 23 patients with adrenal incidentalomas false positivity of USG was found (all on the left side), 4 cases were identified as pseudoadrenal masses. Hormonal activity was proved in 4 out of 15 true adrenal masses (2 pheochromocytomass, 2 aldosteronomas). Five out of 11 hormonally inactive tumors were benign adenomass, 2 myelolipomas, 2 simple cysts, 1 metastasis of bronchogenic carcinoma and 1 tuberculotic involvement. The smallest tumor was aldosteronoma (2 cm in diameter), the largest was myelolipoma (more than 10 cm). Size of benign adenomas ranged between 2.5-4.8 cm. Three main ultrasonic patterns of adrenal tumors were recognized: (1) anechogenic cysts, (2) complex but predominantly hyperechogenic myelolipomas, (3) hypoechogenic all other masses.

Adenoma↗

PubMed1997

[Will determination of prostate specific antigen density improve the diagnosis of prostatic carcinoma?].

Prostate specific antigen (PSA) serum levels in patients with prostate carcinoma and with benign prostate hyperplasia overlap. In order to improve the positive predictive value of PSA in the diagnosis of prostate carcinoma the authors recommend to evaluate the PSA levels in relation to the prostate volume, the so-called density of the prostate specific antigen (PSAD). The correlation of PSA and PSAD with results of bioptic examination revealed that PSAD does not increase the capacity of PSA to predict the presence of prostate carcinoma and does not reduce the number of prostate biopsies. All patients with PSA levels higher than 4 ng/ml and/or a pathological finding on digital rectal examination need a bioptic examination of the prostate.

Aged↗

PubMed1997

[The antiandrogen withdrawal syndrome: decrease in prostate specific antigen serum levels after withdrawal of antiandrogens].

Combined androgen blockade using surgical or medical (luteinizing hormone-releasing hormone agonist) castration in association with anti-androgen has become the primary therapy in patients with metastatic prostate cancer. Patients undergoing combined androgen blockade will progress within 18-30 months after initial hormonal therapy. When progression occurs following combined androgen blockade, the non-steroid anti-androgen should be subsequently withdrawn. Several recent reports have been published on the paradoxical effect of anti-androgen withdrawal. Eight (22.9%) of 35 patients showed a decline in PSA levels following flutamide withdrawal. The mean time to progression following combined androgen blockade was 26 month and the mean duration of response to flutamide withdrawal was 4.1 months.

Aged↗

PubMed1996

The value of prognostic factors in the management of stage I nonseminomatous germ cell testicular tumors (NSGCTT).

The prospective study, carried out from February 1992 to January 1996, included 49 patients in clinical Stage I nonseminomatous germ cell testicular tumors (NSGCTT). They were aged 16-40 years (mean, 25 years). Patients were stratified to different risk-adapted therapeutic approaches according to histopathologic findings of primary tumor removed by inguinal orchiectomy. Eleven patients of the 1st group with vascular invasion and majority of embryonal carcinoma components in the primary tumor were treated with adjuvant chemotherapy (2 cycles of BEP). None of them had disease progression after the follow-up of 4-43+ months (mean, 20.9 months) after orchiectomy. Five patients of the 2nd group with vascular invasion and majority of teratoma elements in the primary tumor were treated with primary retroperitoneal lymph node dissection (RPLND). They were followed-up 29-45+ months (mean, 33.4 months) after orchiectomy. Two of them (40%) had pathologic Stage II after RPLND and underwent subsequent BEP chemotherapy. One of them died due to disease progression in disseminated stage 29 months after orchiectomy. The second one lives with no evidence of the disease (NED). Thirty three patients in the 3rd group without vascular invasion were kept under surveillance. They were followed-up 3-48+ months (mean, 22.3 months) after orchiectomy. Disease progression was observed in 5 of them (15.1%), 7-10 months (mean, 8.8 months) following orchiectomy. These patients were treated with BEP chemotherapy and live with NED 1-16+ months (mean, 9.2 months) after completion of the therapy. The overall survival rate in clinical Stage 1 patients was 97.9%. The authors recommend the surveillance policy only in clinical Stage I NSGCTT patients without vascular invasion in the primary tumor.

Adolescent↗

PubMed1996

Stromal cells maintain the radioprotective capacity of CFU-S during retroviral infection.

Retroviral vectors provide an efficient means to introduce genes into hematopoietic stem cells. In order to develop retroviral infection protocols which preserve the radioprotective capacity of CFU-S, we designed a clonal hematopoietic reconstitution assay. In this assay, single CFU-S-derived derived colonies from bone marrow cells of 5-FU-treated mice were tested for their capacity to prevent radiation-induced mortality. Three parameters which may modify stem cell potential were tested in infection protocols using a retroviral vector containing the gene for neomycin resistance: (1) the partition of stem cells between the adherent and nonadherent fraction; (2) the replacement of the packaging cell line by a "competent' stromal cell line; and (3) the effects of G418 selection. All CFU-S having radioprotective capacity were found in the adherent fraction when the packaging cell line or the stromal cell line (MS-5) chosen for its capacity to maintain long-term bone marrow culture were used during the co-culture. The neo resistance gene was transduced into CFU-S with the same efficiency using co-culture with the packaging cell line or co-culture with the MS-5 cell line plus viral supernatant. However, in the presence of MS-5, a much higher proportion of CFU-S (70% versus 30%) had radioprotective properties, suggesting an important role for the stromal cells in the maintenance of hematopoietic reconstituting ability. Finally, G418 selection, even for a limited period (24 h), significantly decreased the radioprotective capacities of CFU-S (56% versus 18%). Subsequently, hematopoietic reconstitution by single CFU-S was quantified in recipient mice. The progeny of CFU-S were found at a significant level in the blood, spleen and bone marrow in 38% and 15% of mice, 1 and 3 months after transplantation, respectively. These results demonstrate that we have substantially improved the infection protocol. Under these conditions of infection, it is possible to conserve CFU-S properties and to transduce a gene into a stem cell with short-term hematopoietic reconstitution potential.

Animals↗

PubMed1994

High-performance liquid chromatographic determination of ceftibuten and its metabolite in biological fluids: applications in pharmacokinetic studies.

An HPLC method with UV detection was developed for the analysis of ceftibuten (cis-isomer) and its metabolite (trans-isomer of ceftibuten) in plasma and urine. The detection was performed at 254 nm. The procedure for the plasma assay involves the addition of an internal standard (ceftazidime), followed by treatment of the samples with acetonitrile and dichloromethane. The urine samples, after dilution (10- to 40-fold), were analyzed by a column-switching technique without internal standard. The proposed technique is reproducible, selective, reliable, and sensitive. Linear detector responses were observed for the calibration curve standards in the ceftibuten conentration range of 0.10 to 20 mg/L for plasma and 0.10 to 50 mg/L for urine, and in the metabolite concentration range of 0.20 to 4 mg/L for plasma and 0.20 to 16 mg/L for urine. The limit of quantitation is 0.1 mg/L for ceftibuten and 0.2 mg/L for the transisomer in plasma and urine. The reproducibility of the analytical method according to the statistical coefficients is approximately 7%. The accuracy of the method is good; that is, the relative error is < 5%. The methods were applied to pharmacokinetic studies of ceftibuten after multiple oral administration (400 mg every 12 h for 8 days) to healthy volunteers.

Administration, Oral↗

PubMed1994

Multiple-dose pharmacokinetics of ceftibuten after oral administration to healthy volunteers.

The pharmacokinetics of ceftibuten in plasma and urine were investigated after oral administration. Twelve healthy subjects were treated orally twice daily with 400 mg of the drug for 7 days; on day 8, the subjects received a last dose of 400 mg of ceftibuten. Ceftibuten and its metabolite, the trans isomer of ceftibuten, were assayed in plasma and urine by a specific HPLC method with UV detection. Ceftibuten was rapidly absorbed, as evidenced by the mean time to the maximum observed cis-ceftibuten concentration of 2.4 h. To describe the drug intake process, a Weibull model was used. For the metabolite, the mean time to maximum concentration in plasma was 3.25 h. Mean values for the terminal half-life in plasma were 2.17 h for cis-ceftibuten and 3.19 h for trans-ceftibuten. The overall elimination half-life, tmax, and total and renal clearances of cis-ceftibuten were invariant with respect to duration of dosing. The area under the plasma concentration versus time curve from 0 to infinity and the Cmax of this drug were significantly higher on day 8 than the values predicted from the elimination half-life computed on day 1 of treatment and the dosing interval. The pharmacokinetic parameters of trans-ceftibuten were invariant with respect to duration of dosing. Ceftibuten was well tolerated; there were no clinically significant adverse clinical events. The results from the present study indicate that the levels of cis-ceftibuten in plasma as well as in urine remain above the MICs for susceptible organisms over the dosing interval.

Administration, Oral↗

PubMed1994

Willingness of Brazilian dentists to treat an HIV-infected patient.

A study of the willingness of 363 general dental practices in Brazil to accept a patient infected with human immunodeficiency virus for treatment of dental pain and the provision of routine dental care showed only 44% of dental practices to be willing to provide dental care. Willingness was influenced neither by financial factors nor the local prevalence of human immunodeficiency virus disease.

Adult↗

PubMed1994

Murine pluripotent hematopoietic progenitors constitutively expressing a normal erythropoietin receptor proliferate in response to erythropoietin without preferential erythroid cell differentiation.

Erythropoietin (EPO) is a prime regulator of the growth and differentiation of erythroid blood cells. The EPO receptor (EPO-R) is expressed in late erythroid progenitors (mature BFU-E and CFU-E), and EPO induces proliferation and differentiation of these cells. By introducing, with a retroviral vector, a normal EPO-R cDNA into murine adult bone marrow cells, we showed that EPO is also able to induce proliferation in pluripotent progenitor cells. After 7 days of coculture with virus-producing cells, bone marrow cells were plated in methylcellulose culture in the presence of EPO, interleukin-3, or Steel factor alone or in combination. In the presence of EPO alone, EPO-R virus-infected bone marrow cells gave rise to mixed colonies comprising erythrocytes, granulocytes, macrophages and megakaryocytes. The addition of interleukin-3 or Steel factor to methylcellulose cultures containing EPO did not significantly modify the number of mixed colonies. The cells which generate these mixed colonies have a high proliferative potential as shown by the size and the ability of the mixed colonies to give rise to secondary colonies. Thus, it appears that EPO has the same effect on EPO-R-expressing multipotent cell proliferation as would a combination of several growth factors. Finally, our results demonstrate that inducing pluripotent progenitor cells to proliferate via the EPO signaling pathway has no major influence on their commitment.

Animals↗

PubMed1994

[Prostate-specific antigen in patients with benign prostatic hyperplasia].

The authors examined 119 patients with the histological finding of benign prostatic hyperplasia (BPH). Before the planned operation of the prostate (transurethral resection or open prostatectomy) the authors examined in all patients the level of the prostate specific antigen (PSA) and the prostate volume by sonography. Of 119 patients 70 (58.8%) had elevated serum levels of PSA and in 35 (29.4%) the PSA level was higher than 10 ng/ml. The authors demonstrated a highly significant (p < 0.0001) linear relationship of the PSA serum level and volume of prostate in patients with BPH. Based on the results of simple regression analysis they elaborate an equation for the prostate volume: PSA ng/ml = (3.26 + 0.12 x volume of prostate (ml) +/- 8.44). By adding the value of the standard deviation of PSA the authors created an interval in which are most of the patients with BPH. The authors recommend supplementary examinations (transrectal sonography and biopsy of the prostate) in patients where there is a disproportion between the PSA level and the prostate volume.

Adult↗

PubMed1994

[Prophylaxis with ciprofloxacin in transurethral surgery].

The purpose of the study was to compare in a prospective randomized study the effect of three doses of prophylactic administration of ciprofloxacin in 25 patients and a control group of 26 patients without prophylactic antibiotic treatment in conjunction with transurethral surgery. In the group of patients with prophylaxis there is a significantly lower incidence of clinical manifestations of infection, as compared with the group of patients without prophylaxis which reduces the necessity to administer antibacterial drugs during the postoperative period.

Aged↗

PubMed1992

[Comparison of urography and ultrasonography findings in patients prior to prostatectomy].

In order to evaluate the assess of ultrasonographic examinations in patients before prostatectomy the authors correlated preoperative findings obtained by urography with ultrasonographic findings. Urography of the upper urinary pathways revealed 12 (18.8%) pathological findings, ultrasonographic examination 26 findings (40.6%) in a group of 64 patients. While in 14 patients a pathological finding on ultrasonography was not revealed by urography, only in one patient with a positive urographic finding ultrasonography was negative. Ultrasonographic examination proved to be more valuable in assessing the post-miction residue, as compared with urography. Moreover, ultrasonography is useful for assessing the volume of tissue of benign prostatic hyperplasia. Correlation of the calculated volume of prostatic tissue by means of ultrasonography with the weight of removed tissue revealed a close linear correlation. Ultrasonographic examination of patients before prostatectomy replaced urography which proved to be unnecessary diagnostic procedure.

Aged↗

PubMed1991

[Transurethral invaginating ureterectomy].

The principle of transurethral invagination ureterectomy is in the invagination of the stump of the ureter its retraction into the urinary bladder and resection of the levels of the mucosa of the urinary bladder. The authors describe the surgical procedure and experience with the treatment of seven patients.

Aged↗