Biomedical subjects

J Benavente

Publications and source records attributed to J Benavente.

43 records · Page 3Linked to original sources

PubMed1984

Effect of interferon on integrity of vaccinia virus and ribosomal RNA in infected cells.

The state of vaccinia and ribosomal RNAs in IFN-treated, vaccinia virus-infected mouse L cells grown in suspension is examined. In these cells a drastic inhibition (approximately 90%) of both viral and cellular protein synthesis occurs after virus infection of IFN-treated cells. The findings show that (1) primary transcription of vaccinia virus is not impaired by IFN, but is rather enhanced; (2) viral RNAs produced in IFN-treated, infected cells are predominantly of the early class; (3) these viral RNAs can be translated in a cell-free protein-synthesizing system; (4) in IFN-treated, infected cells there is extensive cleavage of 28 and 18 S rRNA at early times post infection, resulting in a characteristic cleavage pattern; (5) cleavage of rRNA is viral RNA dependent. The results indicate that in this virus-cell system the IFN-mediated inhibition of vaccinia and cellular protein synthesis is correlated with an alteration in ribosomal integrity.

Animals↗

PubMed1984

Selective inhibition of viral gene expression as the mechanism of the antiviral action of PGA1 in vaccinia virus-infected cells.

We have previously shown that prostaglandins of the A series are potent inhibitors of the replication of several animal viruses in cultured cells. In this report we have studied the mechanism of the antiviral action of PGA1 in vaccinia virus-infected mouse L cells, where there is an alteration in both the rate and extent of the synthesis of some virus proteins. When cytoplasmic RNAs from PGA-treated, vaccinia virus-infected cells were translated in cell-free systems, similar selective inhibition of the synthesis of some viral polypeptides was observed. The lack of translation of some viral RNAs was not due to an impairment of the methylation process nor to a difference in ionic requirements. PGA1, even at doses as high as 10 micrograms/ml, did not exert any direct inhibitory action on transcription in vitro as measured in two cell-free systems, and had no effect on primary transcription-translation of vaccinia virus RNAs when assayed in coupled cell-free systems. Southern blot hybridization analysis of cytoplasmic RNAs to EcoRI restriction fragments of vaccinia DNA showed that PGA1 was able to induce major changes in the pattern of RNA transcripts during the course of viral infection. We propose that changes in the transcription programme of vaccinia virus RNAs could be due either to an alteration of specific viral proteins that regulate transcription by direct binding of PGA1, or to the synthesis and/or activation of a host product that mediates the antiviral action.

Animals↗

PubMed1984

Indiscriminate degradation of RNAs in interferon-treated, vaccinia virus-infected mouse L cells.

In this report we used Northern blot hybridization analysis to characterize the fate of several species of viral RNA transcribed from internal and terminal regions of vaccinia DNA in interferon-treated, infected mouse L cells grown in suspension. All species of viral RNAs were expressed but were reduced in amount. Larger-sized RNAs were reduced more than smaller-sized RNAs. This reduction appears to be related to the activation of the interferon-mediated double-stranded RNA-dependent 2-5A synthetase-endoribonuclease system, as the rRNA cleavage pattern characteristic of this system was observed early in infection and in cell extracts in response to exogenous 2-5A. Thus, in interferon-treated, vaccinia-infected mouse L cells in suspension, there is indiscriminate degradation of viral and cellular RNAs, and this RNA breakdown might play a role in the interferon-mediated inhibition of protein synthesis.

Animals↗

PubMedDate not supplied

[Prospective studies for determining the duration of prevention in superficial tumors of the bladder].

The study covers a series of 221 patients with pTa or pT1 vesical tumours who were treated by RTU and had an endovesical cytostatic agent instilled prophylactically for a year. Before beginning the tumour resection, biopsies in map with cold forceps were routinely taken from the trigone, side walls, bottom walls and vesical cup. It was decided to monitor the patients by performing cystoscopies and biopsies in map with cold forceps every quarter. During the second and third year the endoscopic and bioptic monitoring was done every six months. During the time when the cytostatic agents were instilled, a significant decrease (p less than 0.01) in the percentage of patients with 'CIS' was observed. After discontinuing the instillation, the percentage of patients with 'CIS' reversed to similar figures as seen prior to the study. It can be deduced from this observation that prophylaxis can be effective against those elements of the urothelial disease which influence the arrival of new events and the increase of the tumoral stage, and that the control of those factors disappears when the prophylaxis is discontinued. The study illustrates that prophylaxis in the urothelial disease should be maintained indefinitely.

Administration, Intravesical↗

PubMedDate not supplied

[Superficial tumor of the bladder with associated carcinoma in situ: new occurrences and increase of tumor stage].

The paper presents our experience with in situ carcinoma associated to bladder surface tumour. The relationship between in situ carcinoma associated to surface tumour and new occurrences, as well as increase of tumoral stage, versus those tumours not associated to in situ carcinoma is assessed through a comparative study. It is concluded that bladder surface tumours with associated in situ carcinoma begin to recur from the first months at higher rate than other surface tumours. Bladder surface tumours with associated in situ carcinoma, however, do not increase tumoral stage at a different rate than other surface tumours, at least not for a period of 18 months.

Carcinoma in Situ↗

PubMedDate not supplied

[Tumor of the vitelline sac of the testicle (yolk sac carcinoma)].

The tumour of the yolk sac is a germinal cell neoplasia arising in the prepubertal testicles which was included in the WHO's histological classification of neoplasia of the testicles in 1977. We contribute a case of this histological variety in Stage I, according to the Royal Marsden criteria. The patient was treated with inguinal orchidectomy only and 3 years later remains disease-free.

Dysgerminoma↗

PubMedDate not supplied

[Toxicity of prophylaxis of superficial bladder tumors].

The paper reviews the various prophylaxis modalities in surface vesical tumours in order to define the degree of toxicity caused by each of them. Also, a prophylaxis diagram is prepared, having into account each substance's toxicity, the benefit awarded to each of then and the tumour prognosis. The agents under assessment are Thiotepa, Adriamycin, Epirubicin, Cisplatin, oral Methotrexate, Mitomycin-C, Mitoxantrone, Interferon and BCG, at doses of 40, 120 and 150 mg. Two groups of prophylactic agents can be identified with regard to toxicity. The first one is constituted by Interferon, Adriamycin, Epirubicin and Mitomycin-C, with side-effects lower than or close to the net benefit estimated for each. The second group comprises cytostatic and immunomodulatory compounds with toxic effects greater than their net benefit. In this group, three different situations can be distinguished: a) BCG with high toxicity and high net benefit; b) Cisplatin, Thiotepa and Mitoxantrone with high toxicity and net benefit similar to that of Adriamycin, Epirubicin and Mitomycin C; and c) Oral Methotrexate, with high toxicity and no benefit. According to their toxicity levels, Interferon, Adriamycin, Epirubicin and Mitomycin C are indicated in the prophylaxis of medium-risk tumours, while BCG only in high-risk tumours. Thiotepa, Cisplatin, Mitoxantrone and oral Methotrexate have to be eliminated due to their negative benefit-toxicity relationship.

Antineoplastic Agents↗