Epidermal melanocytes metabolize extracellular nucleotides by purinergic enzymes

The human epidermal melanocyte (hEM) are melanin-producing cells that provide skin pigmentation and protection against ultraviolet radiation. Although purinergic signaling is involved in skin biology and pathology, the presence of NTPDase members, as well as the rate of nucleotides degradation by melanocytes were not described yet. Therefore, in this study, we analyzed the expression of ectonucleotidases in hEM derived from discarded foreskin of male patients. The expression of purinergic enzymes was confirmed by mRNA and flow cytometry. Among the ectonucleotidases, ectonucleoside triphosphate diphosphohydrolase1 (NTPDase1) and ecto-5´-nucleotidase were the ectoenzymes with higher expressions. The hydrolysis rate for ATP, ADP, and AMP was low in comparison to other primary cells already investigated. The amount of ATP in the culture medium was increased after a scratch wound and decreased to basal levels in 48 h, while the NTPDase1 and P2X7 expressions increased. Therefore, it is possible to suggest that after cell injury, the ATP released by hEM into the extracellular space will be hydrolyzed by ectonucleotidases as the NTPDase1 that will control the levels of nucleotides in the skin micro-environment.

Abstract B70: Identification of reference genes for normalizing gene expression for RT-qPCR analysis in established cervical cancer cell lines and their derived cancer stem like cells

Cervical cancer is the fourth most common cancer affecting women worldwide. Cancer stem cells are a subpopulation of tumor cells related to malignancy, resistance, and poor survival. Considering the importance of gene expression studies to understand cervical cancer stem cells (CCSC) biology and the need of proper validation of reference genes to normalize RT-qPCR data, this work identifies stable reference genes for the cervical cancer cell lines SiHa, HeLa, and ME180 as well as their respective derived cancer stem like cells. A literature review was performed to identify whether validation of reference genes was available for RT-qPCR assays in cervical cancer cell lines. Then cell lines were cultured in regular monolayer or in tumor sphere formation conditions. RT-PCR was carried out to validate cells grown as spheres as CCSC. RT-qPCR was performed using five commonly used reference genes: ACTB, B2M, GAPDH, HPRT1, and TBP. Stability was assessed through analysis of dispersion data and the Normfinder software to validate the selected genes as suitable reference genes. According to the literature review, no validation of reference genes for SiHa, HeLa, or ME180 cells in standard culture conditions or their CCSC subpopulations has been done so far. Our evaluation validated B2M, GAPDH, HPRT1, and TBP in these set conditions. Among them, GAPDH presented the lowest stability value (0.222), being therefore the most adequate gene to normalize the combination of all samples. Moreover, associating GAPDH and TBP led to a more stable value (0.184). These results suggest that B2M, GAPDH, HPRT1, and TBP are suitable reference genes to normalize RT-qPCR data of established cervical cancer cell lines SiHa, HeLa, and ME180 as well as their derived cancer stem like cells. Furthermore, GAPDH seems to be the most convenient choice for studying the combination of these cells.

Citation Format: Rafael Paschoal de Campos, Iago Carvalho Schultz, Paola de Andrade Mello, Samuel Davies, Manuela Sangalli Gasparin, Ana Paula Santin Bertoni, Jéssica Gonçalves Azevedo, Andréia Buffon, Márcia Rosângela Wink. Identification of reference genes for normalizing gene expression for RT-qPCR analysis in established cervical cancer cell lines and their derived cancer stem like cells [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr B70.

Abstract B34: Pyrimidobenzimidazoles as a potential new drug to treat human melanoma

Melanoma is the most aggressive skin tumor due to its high capacity to metastasize and resistance to therapy, leading to poor prognosis and high mortality rates. Thus, the aim of this study was to investigate a possible antitumoral action of pyrimidobenzimidazole compounds in human melanoma lineages, SK-Mel-103, SK-Mel-28, and SK-Mel-28 resistant to vemurafenib. Using acute treatment (72 hours) it was possible to select two, among the seven compounds tested, by their effectiveness in decrease the cell viability, by MTT assay, in low concentrations. Further, using chronic assay (120 hours) it was possible to find the IC50 of the best compounds, PBZs 1 and 4. For cell line SK-Mel-103 the IC50 value was 3.2 µM and 4.0 µM, for the two more potent compounds respectively, and for cell line SK-Mel-28 IC50 of 9.7 µM and 9.6 µM was obtained for PBZ01 and PBZ04, respectively. These compounds, alone or in combination with DTIC, were used to analyze the cumulative population doubling, in an attempt to simulate the treatment cycle used for patients. The results show that PBZs 1 and 4, especially when in combination with dacarbazine, were able to cause a significant decrease in the population growth rate and in the number of colonies in clonogenic assay, of the SK-Mel-28, better than dacarbazine alone and in lower concentration. Also, it is important to highlight that the effect of PBZs was selective to melanoma, considering that it did not cause relevant effect in melanocyte and in the proliferative nontumoral cell line, MRC5. The cell cycle analysis showed that the treatment alters the cell complexity, increasing the size (FSC) and granularity (SSC). Furthermore, when vemurafenib-resistant cells were treated with PBZ (cotreatment with vemurafenib), there were a population decrease in the population doubling assay more than vemurafenib alone. These results are important and encourage the study of the mechanism by which these compounds affect the melanomas' viability as well as the development of a preclinical model to confirm their effectiveness in vivo.

Citation Format: Jéssica Gonçalves Azevedo, Iago Carvalho Schultz, Jacqueline Fraga de Souza Santos, Silvya Stuchi Maria-Engler, Guido Lenz, Marcia Rosângela Wink. Pyrimidobenzimidazoles as a potential new drug to treat human melanoma [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr B34.

Prevalence and risk factors for hepatitis C antibodies in volunteer blood donors in Brazil

BACKGROUND

Little is known about the prevalence, risk factors, and transmission of hepatitis C virus (HCV) in a nontransfused population, particularly in developing countries.

STUDY DESIGN AND METHODS

To investigate the association between HCV seropositivity and some demographic variables, a case-control study was conducted on 138 seropositive donors among 4762 consecutive volunteer blood donors and 1101 seronegative controls in Rio de Janeiro, Brazil. Donors were initially screened by interview for male homosexuality, use of illicit drugs, tattoos, previous transfusions, venereal diseases, and jaundice. Eligible donors were then tested for HCV antibodies by enzyme-linked immunosorbent assay. A multivariate analysis was performed on age, ethnic group, gender, and prior donation.

RESULTS

The overall prevalence of HCV seropositivity was 2.89 percent. An increased risk of seropositivity was demonstrated for nonwhite donors at an odds ratio of 2.11 (95% CI, 1.43-3.13), for males at 2.39 (95% CI, 1.01-5.7), and for prior donors at 1.66 (95% CI, 1.09-2.52). The risk of anti-HCV positivity increased markedly with age. Those at highest risk were the group 40 to 49 years old, with an odds ratio of 4.37 (95% CI, 2.39-7.99) versus the group 20 to 29 years old. The group under 20 years old showed an odds ratio of 0.50 (95% CI, 0.06-3.87) compared to the group 20 to 29 years old. These findings were equally significant in a univariate analysis.

CONCLUSION

Our results suggest that HCV seropositivity is strongly associated with male sex, nonwhite ethnicity, and greater age. A significant number of seropositive donors were not detected by screening interview.

[Value of transesophageal echocardiography in the diagnosis of acute aortic dissection]

We describe our experience of six patients with clinical suspicion of acute aortic dissection (AAD) who were studied consecutively by transesophageal echocardiography (TEE) from April to July of 1991. All of them were previously submitted to transthoracic echocardiogram. The diagnosis was correctly established by TEE in five cases, confirmed by aortography and/or surgery (four cases), or by autopsy (one case). In one patient the diagnosis of AAD was excluded by TEE, and posteriorly by nuclear magnetic resonance. Four patients had a Stanford type A, and one patient a type B dissection. The site of entry was identified in three cases; the intimal entry tear of the type B dissection, not observed by TEE, was localized in the aortic arch by aortography. In three of the four type A dissection cases, a thrombus in the false lumen and an aortic regurgitation were found. No other noninvasive methods were used after the diagnosis of AAD by TEE. The surgical repair was successful in three cases, one of which, without previous necessity of aortography. In our experience, TEE increased extraordinarily the diagnosis efficacy of AAD, making possible an earlier therapeutic approach, and probably contributing to the improvement of the prognosis of this pathology.

[Transcutaneous pacemaker in cardiovascular emergencies]

OBJECTIVES AND DESIGN OF THE STUDY: Retrospective study to evaluate the efficacy and tolerance of the transcutaneous cardiac pacemaker in the urgent treatment of asystole or severe bradycardia.

SETTING

Coronary Care Unit (CCU) and emergency area of the central reference Hospital.

PATIENTS

24 patients, 20 males and four females, aged between 57 and 84 years (mean 70.4 +/- 7.9). Five pts were in asystole and 19 in severe bradycardia.

INTERVENTIONS

The transcutaneous pacemaker used, was the "Cardio Aid Zoll NTP" model. The intensity of the electrical stimulation was increased progressively, until electrical capture or intolerable discomfort by the patients was achieved. We defined by electric efficacy, the visualization of pacing spike followed by a deflection due to ventricular depolarization; and by hemodynamic efficacy, the evidence of myocardial contraction, defined as a palpable pulse, synchronous with the pacing artefact.

MAIN RESULTS

Stimulation threshold ranged from 30 to 140 mA (mean 67.7 +/- 23.4). The duration of pacing was from 15 minutes to 13 hours, being more than one hour in only four situations. From the 20 conscious patients, or the ones who got conscious, 15 (75%) tolerated well the stimulation. It was intolerable in five pts (25%). No significative side effects due to the use of transcutaneous pacemaker were observed.

CONCLUSIONS

The transcutaneous pacemaker was efficient in the electric and hemodynamic stabilization in the majority of patients. It was generally well tolerated and without important side effects. We think that it may be a valid alternative to transvenous pacing technics in the treatment of asystole and severe bradycardia situations.

[Indirect criteria of coronary reperfusion and permeability in patients with acute myocardial infarction who have received thrombolytic therapy]

OBJECTIVE

To evaluate the value of some indirect reperfusion signs (IRS) as markers of coronary artery patency in patients (PTS) with acute myocardial infarction (AMI) submitted to intravenous (IV) thrombolytic therapy (TT).

DESIGN

Retrospective study, with analysis of the sensibility (S), specificity (SP) and predictive value (PV) of three IRS: 1. Pain and ST resolution in the first three hours; 2. Peak CK in the first 13 hours; 3. accelerated idioventricular rhythm (AIVR) in the first three hours.

SETTING

Coronary Care Unit (CCU) of the Santo António Hospital and Hemodynamic Laboratory of the S. João Hospital, Oporto.

PATIENTS

Sixty seven PTS (mean age 53.4 +/- 10.6 years) with confirmed AMI, 62 male and five female, 34 with anterior and 33 with inferior infarction, TT started in the first three hours of the beginning of symptoms in 34 PTS and from three to six hours in 33 PTS, all submitted to coronary angiography in the hospital setting (7.6 +/- 5.9 days after AMI).

INTERVENTIONS

IV administration of 1,500,000 U of streptokinase (SK) in 47 PTS and 30 U of APSAC in 20 PTS, preceded by 200 mg IV prednisolone and oral 100 mg acetilsalicylic acid, and followed by IV heparin therapy. Continuous electrocardiographic monitoring, and serial 12 leads ECG and enzymatic assays (at start and 1, 3, 7, 13 and 25 hours of TT). Analysis of the correlation of the three IRS (isolated and in association) with coronary artery patency (TIMI 2 or 3).

MEASUREMENTS AND RESULTS

The total patency rate was 79.1%; there was no statistically significant difference with regard to AMI location, time of symptoms onset (0-3 vs 3-6 hours) or thrombolytic agent (SK vs APSAC). The first and second IRS had a high S and a low SP; together S = 79.2%, SP = 64.3% and PV = 89.4%. The third IRS with the first and/or the second one had a low S (about 25%) but SP and PV of 100%. The coronary patency rate of PTS without IRS was always greater than 50%.

CONCLUSIONS

The analysed IRS although not very reliable are useful when considered in association. It is possible to assess PTA with high probability of reperfusion if AIVR is present. The absence of IRS does not exclude coronary artery patency. There is still missing more reliable no-invasive reperfusion markers.

Incidence of retroviruses in some Brazilian groups

The prevalence of human T lymphotropic virus type I (HTLV-I) and human immunodeficiency virus (HIV) antibodies was evaluated in Brazil among 116 aboriginal Indians living in a pre-Amazonian region, and in 44 patients with haematological malignant disorders being treated in Rio de Janeiro. Screening for the presence of antibodies to HIV was performed routinely for 17,224 blood donors at the National Cancer Institute, Rio de Janeiro, from January 1986 to May 1987. The results demonstrated that HIV infection was not endemic among Brazilian Indians, as none of them had antibodies to HIV, in contrast with the population of Rio de Janeiro, which showed a high prevalence (0.34%) of positivity among normal individuals. In a small group of patients with haematological disease only one with acute lymphoblastic leukaemia proved to be HIV-positive, the infection having been acquired through previous blood transfusion. None of the serum samples reacted with HTLV-I, including those of 17 non-Hodgkin's lymphoma patients. HTLV-I infection does not seem to be endemic in this country, but further large scale studies are necessary, especially in patients with haematological disorders, homosexual individuals and drug users.