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Biomedical subjects

A Caputo

Publications and source records attributed to A Caputo.

At least 109 records · Page 6Linked to original sources
PubMed1984

BK virus-plasmid expression vector that persists episomally in human cells and shuttles into Escherichia coli.

We describe a novel expression vector, pBK TK-1, that persists episomally in human cells that can be shuttled into bacteria. This vector includes sequences from BK virus (BKV), the thymidine kinase (TK) gene of herpes simplex virus type 1, and plasmid pML-1. TK+-transformed HeLa and 143 B cells contained predominantly full-length episomes. There were typically 20 to 40 (HeLa) and 75 to 120 143 B vector copies per cell, although some 143 B transformants contained hundreds. Low-molecular-weight DNA from TK+-transformed cells introduced into Escherichia coli were recovered as plasmids that were indistinguishable from the input vector. Removal of selective pressure had no apparent effect upon the episomal status of pBK TK-1 molecules in TK+-transformed cells. BKV T antigen may play a role in episomal replication of pBK TK-1 since this viral protein was expressed in TK+ transformants and since a plasmid that contained only the BKV origin of replication was highly amplified in BKV-transformed human cells that synthesize BKV T antigen.

BK Virus↗
PubMed1984

Lonidamine, a new approach to cancer therapy.

The experimental and theoretical bases for the use of Lonidamine in cancer therapy are reviewed and discussed. In murine tumors Lonidamine has a narrow spectrum of antitumor effects. It lacks the characteristic properties of antiproliferative drugs, as well as other important pharmacological actions, with the exception of antispermatogenic and embryotoxic effects which are closely related to the antitumor ones. Lonidamine appears not to affect the cell division processes. Available data instead show that it specifically affects the condensed or oxidized mitochondrion; since tumor cells have a mitochondrially bound hexokinase, both respiration and glycolysis are decreased. There is some evidence that hyperthermia, X rays and some chemotherapeutic agents, when used in combination with Lonidamine, increase the response of tumor cells or systems to this drug.

Abnormalities, Drug-Induced↗
PubMed1983

Episomal DNA of a BK virus variant in a human insulinoma.

BK virus (BKV) DNA was detected by blot hybridization in a human adenoma of pancreatic islets from patient I.R. BKV DNA was free, and no evidence was found of viral sequences integrated into cellular DNA. Virus was rescued by transfection of human embryonic fibroblasts with tumor DNA. The DNA from rescued virus (BKV-IR) was different from wild-type BKV DNA by restriction endonuclease mapping. The genome of BKV-IR is 235 base pairs (bp) shorter than the genome of wild-type BKV. This alteration originates from a deletion of approximately 300 bp involving HindIII fragments B and D, and an insertion of 70 bp in the region of HindIII fragment C. Transformation of hamster kidney cells was induced by total tumor DNA as well as by BKV-IR and BKV-IR DNA. No antibodies to BKV tumor (T) antigen were detected in the patient's serum by immunofluorescence. The significance of episomal BKV DNA in a human tumor is discussed.

Adenoma, Islet Cell↗
PubMed1983

The effect of the association of Gossypol and Lonidamine on the energy metabolism of Ehrlich ascites tumor cells.

The effect of the association of Gossypol and Lonidamine on the energy metabolism of Ehrlich ascites tumor cells has been investigated. The action of the drug on tumor cells was studied by addition of the drugs to cells harvested from Swiss male mice. The results may be summarized as follows: (1) Low concentrations of Gossypol increase the rate of oxygen consumption by uncoupling oxidative phosphorylation. High concentrations result in an inhibition of oxygen consumption with a mechanism that must be regarded as not directly related to the uncoupling activity. (2) Gossypol, at concentrations at which it exerts an uncoupling activity, stimulates mitochondrial ATPase which in turn increases the aerobic and anaerobic rates of lactate production. The decrease of glycolysis at high concentrations of Gossypol does not depend on the inhibition of enzymes of the glycolytic pathway, but must be ascribed to cell death. (3) The association of a low concentration of Gossypol with Lonidamine brings about a further inhibition of oxygen consumption. Moreover, Lonidamine abolishes the stimulation of glycolysis induced by Gossypol and lowers lactate production to values that are quite similar to those found with Lonidamine alone. (4) It may be concluded that the association of Gossypol and Lonidamine results in a very effective decrease of the energy requirements of cancer cells.

Aerobiosis↗
PubMed1983

Percutaneous angioplasty for treatment of renovascular hypertension.

In this study, 10 patients with renovascular hypertension were treated with percutaneous transluminal angioplasty (PTA). The obstructive lesion was atherosclerotic in four cases, fibrodysplastic in five, and mixed in one. Stenosis was bilateral in two patients. Before PTA, all patients had sustained hypertension, in nine despite medication. Immediately after PTA, hypertension was cured (BP less than or equal to 140/90 mmHg without medication) in six patients, and improved (either a BP less than or equal to 140/90 or a decrease in diastolic BP greater than 15 mmHg, with equal or less medication) in three patients. The one failure occurred in the only patient in which PTA did not achieve a complete dilatation of the stenosed artery. The overall success rate was 90 per cent after a mean follow-up of 17.5 months.

Adult↗
PubMed1983

Formation of oligomeric free BK virus DNA is required for tandem integration of viral genomes into cellular DNA.

Mouse kidney cells have been transformed by linear BK virus (BKV) DNA with cohesive ends. These BKV genomes can circularize and subsequently replicate or physically join end to end yielding oligomeric viral DNA molecules. Blot hybridization analysis of transformed cells showed the presence of BKV DNA both in free circular forms and integrated into cellular DNA in a tandem head-to-tail array of full-length viral genomes. Formation of oligomers either by replication via previous circularization or by end to end joining is hindered after elimination of cohesive termini by digestion with the single-strand-specific nuclease S1. After treatment of linear BKV DNA with nuclease S1 only integrations of single viral genomes were observed in transformed cells; tandem insertions and free viral DNA were absent. These results support the hypothesis that formation of tandems of free viral DNA is a necessary prerequisite for tandem integration of viral genomes.

Animals↗
PubMed1982

Oncogenity of BK virus for immunosuppressed hamsters.

Tumors were induced by BK virus (BKV) inoculated intravenously in 3-week-old Syrian golden hamsters immunosuppressed with anti-lymphocyte serum or methylprednisolone acetate alone or in association with gamma-radiation (60Co). The induced neoplasms were ependymoma, carcinoma of pancreatic islets, lymphoma, osteosarcoma, undifferentiated sarcoma, kidney and renal pelvis carcinoma, pheochromocytoma and hemangiosarcoma. High levels of insulin and glucagon and altered concentrations of glucose were detected in blood of animals with tumors of pancreatic islets. No antibodies to BKV tumor antigen (TAg) and low levels of hemagglutination-inhibition antibodies to BKV viral coat protein Ag were detected in hamster sera. BKV TAg was found in tumors by complement fixation. Blot hybridization analysis of tumor DNA showed the presence of both free and integrated BKV genomes in tumor cells. BKV DNA inoculated intravenously and subcutaneously in immunosuppressed or immunocompetent hamsters was not oncogenic, whereas it was weakly oncogenic when inoculated intracerebrally.

Animals↗
PubMed1982

Effect of oxidation on ceramometal bond strength.

The ceramometal bond strength between SMG-3 gold alloy and Ceramco porcelain was evaluated using seven different oxidation cycles. The control group was not oxidized. Three groups were oxidized under vacuum at a temperature of 1,925 degrees F. The metal was heated (1) just until it reached temperature, (2) for 5 minutes, and (3) for 10 minutes. The last three groups were oxidized without a vacuum, with the time-temperature heat regimen the same as for the previous three groups. The group using an oxidation cycle without a vacuum and a temperature of 1,925 degrees F for 10 minutes was the only group that statistically differed from the control group.

Chemical Phenomena↗
PubMed1982

Construction and identification by partial nucleotide sequence analysis of bovine casein and beta-lactoglobulin cDNA clones.

Double stranded (DS) DNA molecules obtained by reverse transcription of a partially purified lactating bovine mammary gland mRNA fraction were cloned into pBR322. Restriction maps for four recombinants were constructed and partial nucleotide sequence analysis of these revealed coding sequences corresponding to alpha s1-, beta-, and kappa-casein and beta-lactoglobulin. The specific single-stranded (SS) cDNAs representing each of these species were identified and their nucleotide lengths estimated. Evidence is presented that these are essentially full-length transcripts of the major mRNA species. On this basis, the cDNA clones range in size from 50% for beta-casein to about 95% for alpha s1-casein in comparison with their respective mRNAs. The DNA sequence spanning all eight phosphoserine residues in alpha s1-casein is presented. These data, together with other serine codon usage data, indicate that the mammary gland phosphoseryl tRNA does not play a role in the incorporation of serine phosphate residues during casein synthesis. The observation that the nucleotide sequences for the serine phosphate cluster in bovine alpha s1-and rat beta-casein exhibit close homology supports the suggestion that these regions have evolved from a common primordial sequence.

Animals↗
PubMed1982

Transformation of human embryonic fibroblasts by BK virus, BK virus DNA and a subgenomic BK virus DNA fragment.

Human embryonic fibroblasts (HEF) have been transformed by BK virus (BKV) DNA and by u.v.-inactivated or live BKV alone or in association with methyl-cholanthrene (MTC). The transformed cells produced BKV large T and small t antigens as well as the cellular 53 kdal protein, detected by immunofluorescence and immunoprecipitation. After an initial phase of lysis and virus shedding, virus or its coat protein antigen could not be detected in transformed cells. All human transformed cell lines could be superinfected by BKV or BKV DNA, but their susceptibility to superinfection was 20- to 500-fold lower than normal HEF. BKV could be rescued by fusion of transformed cells with normal HEF or Vero cells and by transfection of normal HEF with total DNA and DNA extracted from the Hirt supernatant of transformed cells. Blot hybridization analysis of DNA from transformed cells showed a considerable amount of free BKV DNA in monomeric and polymeric forms. Integrated BKV DNA was absent in most cell lines but present in only small amounts in BKV-transformed cells treated with MTC. Analysis of free BKV DNA with various restriction endonucleases and by blot hybridization showed that monomeric forms were complete BKV genomes, whereas polymers contained both complete and defective or rearranged BKV DNA. Transformation of HEF was also obtained with a 3.7 kilobase (kb) fragment of the BKV genome, produced by sequential digestion of BKV with the restriction endonucleases HhaI and EcoRI. This fragment extends clockwise on the virus genome from 0 to 72.2 map units and contains the entire early region. Blot hybridization analysis of cells transformed by the HhaI/EcoRI 3.7 kb fragment showed two separate integrations of BKV sequences without free virus DNA.

Antigens, Viral↗
PubMed1982

Transformation of hamster kidney cells by fragments of BK virus DNA.

Hamster kidney cells were transformed, with comparable efficiency, by circular or linear molecules of complete BK virus (BKV) genome and by agarose gel-purified fragments of BKV DNA obtained by single or double digestions with various restriction endonucleases. Only fragments containing the complete early region of BKV DNA displayed transforming activity. Analysis by blot hybridization of the arrangement of viral DNA sequences in a cloned cell line transformed by a 3.8-kilobase fragment, obtained after sequential digestion of BKV DNA with HhaI and BamHI, showed the presence of seven viral integrations into the cellular DNA. Apparently all of the integrated viral molecules contained the entire early region of BKV DNA. Large T antigen, small t antigen, and the 56,000-dalton nonviral Tau antigen were detected in transformed cells by immunoprecipitation. The pattern of integration of viral sequences in transformed cells was constant over many generations. Likewise, large T antigen was always detected in transformed cells at various passage levels. These results may suggest that all of the sequences of the early region coding for large T antigen are required for transformation by BKV. Alternatively, subgenomic segments of the BKV DNA early region may be unable to transform because the appropriate polyadenylation site, necessary to obtain a complete functional transcriptional unit, is removed by the restriction enzyme cleavage.

Animals↗
PubMed1981

[Preliminary studies on the characterization of adenylate cyclase from segmental ganglia of the leech Hirudo medicinalis].

Adenylate cyclase activity has been measured in segmental ganglia of the leech Hirudo m. Basal enzymatic activity was stimulated in a dose dependent fashion by serotonin. GTP is required in order to evoke maximal stimulation. The effect was blocked by methysergide, an antagonist of serotonin at receptor level. The stimulation of the enzyme was prevented by alpha beta-methy-len-ATP. In addition RMI 12330A inhibited basal as well as serotonin-stimulated adenylate cyclase activity presumably by acting at the catalytic subunit level.

Adenosine Triphosphate↗
PubMed1981

Lonidamine, a selective inhibitor of aerobic glycolysis of murine tumor cells.

The action of Lonidamine [1-(2,4-chlorobenzyl)-1H-indazol-3-carboxylic acid] on respiration and aerobic lactate production of several murine tumor cells and normal differentiated murine cells was investigated. Lonidamine reduced the oxygen consumption in both normal and neoplastic cells. In contrast, it increased the aerobic glycolysis of normal cells but inhibited that of tumor cells. This selective action might be ascribed to the inhibition of mitochondrially bound hexokinase, which is usually absent in normal differentiated cells.

Animals↗
PubMed1981

Effect of lonidamine on the energy metabolism of Ehrlich ascites tumor cells.

The action of Lonidamine [1-(2,4-dichlorobenzyl)-1-H-indazol-3-carboxylic acid] on oxygen consumption and the rate of aerobic and anaerobic lactate production by Ehrlich ascites tumor cells has been investigated. The rate of oxygen consumption decreases exponentially with the increase of Lonidamine concentration, with maximal inhibition occurring at 0.40 mM Lonidamine. The rate of aerobic lactate production is inhibited to the same extent as is the oxygen consumption. However, the maximum effect is observed at 0.12 mM Lonidamine, and the decrease is linear with Lonidamine concentration. Anaerobic lactate production is more sensitive to Lonidamine, and complete inhibition can be observed by raising the concentration to 0.6 mM. The possibility that the decrease observed in lactate production was secondary to the inhibition of sodium- and potassium-containing adenosinetriphosphatase was excluded, because the drug has no effect on this enzyme. Mitochondrial adenosinetriphosphatase was not affected. Lonidamine was, however, shown to inhibit the activity of mitochondrially bound hexokinase to approximately the same extent as it inhibited aerobic glycolysis (approximately 70%). It is concluded that inhibition of the glycolysis of Ehrlich ascites tumor cells by Lonidamine results from an effect of the drug on the mitochondrially bound hexokinase.

Aerobiosis↗