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Biomedical subjects

P Langen

Publications and source records attributed to P Langen.

At least 55 records · Page 3Linked to original sources
PubMed1984

Purification of a growth inhibitor for Ehrlich ascites mammary carcinoma cells from bovine mammary gland.

A growth inhibitor for Ehrlich ascites mammary carcinoma cells in vitro has been purified from bovine mammary gland. The purification procedure involving homogenization and differential centrifugation under hypotonic conditions, ammonium sulfate precipitation, ultrafiltration, gel chromatography and preparative polyacrylamide gel electrophoresis (PAGE) yielded an inhibitor showing half-maximal inhibition of cell proliferation in concentrations of 1-3 ng protein per ml. Upon 125I labelling and analysis by SDS gel electrophoresis, most purified preparations revealed a single band of 12-14 kD, likely to be representative for the inhibitory protein. The inhibitor was shown to affect resumption of proliferation of stationary cells; however, it was inactive towards cells stimulated by incubation with medium before adding the inhibitor. The inhibitor is heat-labile, does not act by exhausting essential components of culture medium, and its action is antagonized by insulin.

Animals↗
PubMed1984

Antiherpes activity of some novel analogues of (E)-5-(2-bromovinyl)-2'-deoxyuridine (E-BrVUdR) in two different cell lines.

In a series of 5-vinyl-2'-deoxyuridine (VUdR) analogues (5-(2-X-vinyl)-UdRs) the (E)-5-(2-bromovinyl)-UdR (E-BrVUdR) proved the most potent inhibitor of plaque formation of two herpes simplex virus type 1 (HSV-1) strains in human embryonic lung fibroblast (HELF) and African green monkey kidney (Vero) cell cultures. The (Z)-5-(2-bromovinyl)-UdR (Z-BrVUdR) isomer and the 5-(2,2-dibromovinyl)-UdR (Br2VUdR) analogue were 10-20 times less efficient, whereas the (E)-5-(2-cyanovinyl)-UdR (CNVUdR) and the (E)-5-(2-carboxyvinyl)-UdR (COOHVUdR) derivative were only marginally active (10(3)-10(4) times less than E-BrVUdR). The antiherpes potential of the 5-(2-X-vinyl)-UdRs was compared with that of 5-iodo-, 5-fluoro-, 5-formyl- and 5-ethyl-UdR (IUdR, FUdR, fUdR, EUdR) as well as of 9-(2-hydroxyethoxymethyl)guanine (acyclovir, ACV), 2'-fluoro-5-iodo-1-beta-D-arabinofuranosyl(ara)-cytosine (FIAC), 2'-fluoro-5-methylarauracil (FMAU), arabinosylthymine (araT) and (E)-5-(2-bromovinyl)- and 5-vinyl-araU (BrVaraU, VaraU). In HELF cells the following order of decreasing activity against HSV-1-77 was found: E-BrVUdR greater than greater than BrVaraU greater than VaraU greater than FIAC greater than FMAU = VUdR = = Z-BrVUdR = ACV = araT = FUdR greater than Br2VUdR greater than greater than IUdR greater than fUdR greater than EUdR greater than CNVUdR greater than COOHVUdR. The inhibition of HSV-1 replication by most of the investigated compounds was somewhat weaker in the plaque inhibition assay on Vero than on HELF cells, but, in the case of the 5-X-araU reference compounds the activity was strongly reduced in Vero cells. In HELF cells the order of decreasing potential against HSV-2 strain 42/78 (HSV-2-42/78) was: FIAC = FMAU greater than greater than araT greater than IUdR = VUdR greater than ACV = FUdR = greater than fUdR = EUdR = VaraU greater than E-BrVUdR greater than Z-BrVUdR greater than Br2VUdR greater than greater than BrVaraU; CNVUdR and COOHVUdR were nearly inactive.

Antiviral Agents↗
PubMed1984

Differential antiherpes activity of the (E)-and (Z)-isomers of 5-(2-fluorovinyl)-2'-deoxyuridine (FVUdR).

Four novel analogues of (E)-5-(2-bromovinyl)-2'-deoxyuridine [(E)-BrVUdR]--the (E)- and (Z)-isomer of 5-(2-fluorovinyl)-UdR (FVUdR), (Z)-5-(2-carboxy-2-fluorovinyl)-UdR [(Z)-COOH-FVUdR], and (E)-5-(2-ethoxyvinyl)-UdR [(E)-EOVUdR] were compared with the reference compounds (E)-BrVUdR and 5-vinyl-UdR (VUdR) for their inhibitory effects on plaque formation of herpes simplex virus type 1 (HSV-1 strain 77) and type 2 (HSV-2 strain 82) in human embryonic lung fibroblast (HELF) cell cultures. (Z)-FVUdR and (Z)-COOH-FVUdR were completely inactive against HSV-1 and HSV-2 (ID50 greater than 500 microM). For the other analogues the following order of decreasing potency was found: (E)-BrVUdR greater than VUdR greater than (E)-FVUdR much greater than (E)-EOVUdR (against HSV-1) and VUdR much greater than (E)-BrVUdR greater than (E)-FVUdR much greater than (E)-EOVUdR (against HSV-2).

Cells, Cultured↗
PubMed1984

Fetal calf serum and epidermal growth factor prevent the inhibitory action of a chalone-like growth inhibitor for Ehrlich ascites mammary carcinoma cells in vitro.

A growth inhibitor for the Ehrlich ascites mammary carcinoma, purified from bovine mammary gland, is antagonized by very low concentrations of epidermal growth factor (2-16 X 10(-10) M) or fetal calf serum (0.001-0.1%). Thus, epidermal growth factor and the compounds in fetal calf serum have the same effect as earlier described for insulin and proinsulin [1-3].

Animals↗
PubMed1984

Is ribonucleotide reductase in Ehrlich ascites mammary tumour cells the target of a growth inhibitor purified from bovine mammary gland?

2'-deoxycytidine (dCyd), 2'-deoxyuridine (dUrd) and cytidine (Cyd) were found to relieve the inhibitory action by a factor, highly purified from bovine mammary gland, on the resumption of growth in vitro of stationary Ehrlich ascites mammary tumour cells. As described earlier, this effect is also achieved by insulin, proinsulin and epidermal growth factor and fetal calf serum. The effect of purine-2'-deoxyribonucleosides could not be properly assessed, because they were inhibitory themselves. Purine ribonucleosides as well as uridine and uracil were inactive. Because of the inactivity of the latter two compounds, the effect is attributed to an influence of the factor on the ribonucleotide reductase (RR) (and not on the de novo pyrimidine synthesis). The active nucleosides need not be present for the whole incubation time of 24 h; when treated for 4 h with the nucleosides, which are then removed before the addition of the factor, cells become insensitive against the latter. Again a similar effect has been described earlier for serum and insulin. The inhibitor of RR, hydroxyurea, prevents this specific effects of serum and (partially) insulin as well that of dCyd, also suggesting the involvement of RR in the factor action.

Animals↗
PubMed1983

Antiherpes activity of (E)-5-(2-bromovinyl)- and 5-vinyl-1-beta-D-arabinofuranosyluracil and some other 5-substituted uracil arabinosyl nucleosides in two different cell lines.

Of a series of 5-substituted 1-beta-D-arabinofuranosyluracil (5-X-araU) analogues, (E)-5-(2-bromovinyl)-araU(BrVaraU) and 5-vinyl-araU (VaraU) were the most potent inhibitors of plaque formation by two herpes simplex virus type 1 (HSV-1) strains in human embryonic lung fibroblast (HELF) cell cultures. They were not only more active than 5-methyl-araU (MaraU, araT) and 5-ethyl-araU (EaraU), but even more than 1000 times more potent than the 5-fluoro, 5-iodo, 5-formyl and 5-trifluoromethyl (FaraU, IaraU, faraU, CF3araU) analogues. BrVaraU and VaraU were superior to 9-(2-hydroxyethoxymethyl)guanine (Acyclovir, ACV) and comparable in potency with 2'-fluoro-5-iodoaracytosine (FIAC) and 2'-fluoro-5-methylarauracil (FMAU). Their anti-HSV-1 potency was surpassed only by (E)-5-(2-bromovinyl)-2'-deoxyuridine (BrVUdR). Surprisingly, in a HSV-1 plaque inhibition assay in African green monkey kidney (Vero) cells, BrVaraU and VaraU were nearly 100 times active or even inactive. In contrast, the antiherpes activity of ACV, FIAC, FMAU and BrVUdR differed only marginally in the two cell lines. The following order of (decreasing) activity against HSV-2 in HELF cells was found: FIAC = FMAU greater than MaraU (araT) greater than ACV greater than VaraU greater than BrVUdR greater than CF3araU greater than IaraU greater than FaraU = Eara U greater than BrVaraU greater than araU greater than faraU. When deoxyribose is replaced by arabinose in 5-X-UdR analogues, a slight increase in anti-HSV-1-77 activity was observed for the 5-vinyl or 5-ethyl substituent, whereas the other 5-X-araU nucleosides were two to more than 100 times less active than their deoxyribosyl counterparts. However, the sugar exchange led to a strong reduction in anti-HSV-2 activity regardless of the 5-substituent.

Animals↗
PubMed1983

Purification of a chalone-like inhibitor for Ehrlich ascites mammary carcinoma cells from bovine mammary gland.

A factor which inhibits the resumption of proliferation of stationary Ehrlich ascites mammary carcinoma (EAC) cells in vitro was isolated from the normal, lactating bovine mammary gland. After fractionation of the 50,000 g supernatant of the tissue homogenate by ammonium sulfate precipitation and gel filtration, it was further purified 2600-fold by ultrafiltration and lectin affinity chromatography. Polyacrylamide electrophoresis revealed one band containing all the activity. SDS gel electrophoresis showed a main band corresponding to a protein with a molecular weight of about 15,000 dalton. At this state of purity the factor concentration for half-maximal inhibition of proliferation was 12 ng/ml or 8 X 10(-10) M. The effects of factor concentrations of 4 X 10(-9) or 4 X 10(-8) M are abolished by 5 X 10(-9) M insulin almost completely or to 70%.

Animals↗
PubMed1983

Aspects of chalone action.

The following aspects of action of a chalone-like factor for the Ehrlich ascites mammary carcinoma and of the granulocytic chalone are discussed: 1) Dependence on the state of proliferation. Rapidly growing cells respond poorly or not at all. 2) Antagonism with growth factors. The factor for the Ehrlich ascites mammary carcinoma is antagonized by physiological concentrations of insulin or by proinsulin. The granulocytic chalone is antagonized by colony stimulating factor. 3) Influence on cell cycle progression. Attempts and problems to analyse this influence for the factor for the Ehrlich ascites mammary carcinoma by flow cytometry are described.

Animals↗
PubMed1982

Efficiency and selectivity of (E)-5-(2-bromovinyl)-2'-deoxyuridine and some other 5-substituted 2'-deoxypyrimidine nucleosides as anti-herpes agents.

A number of novel 5-substituted 2'deoxypyrimidine nucleosides exhibited antiviral activity against herpes simplex virus type 1 strain V3 (HSV-1-V3) when assayed under one-step conditions in primary human lung fibroblast j(PHLF) cell cultures, and compared with the reference compounds cytosine arabinoside (ara-C), 5-iodo-2'-deoxyuridine (IUdR), and 5-iodo-5'amino-2',5'-dideoxyuridine (AIU). The most effective of these were (in order of decreasing activity): (E)-5-(2-bromovinyl)-UdR (BrVUdR) greater than ara-C greater than IUdR greater than 5-azidomethyl-UdR (AMeUdR) greater than 5-formyl-UdR (fUdR) greater than 5-hydroxymethyl-UdR (HMeUdR) greater than AIU greater than 5-mercaptomethyl-UdR (MMeUdR) = 5-hydroxymethyl-2'-deoxy-cytidine (HMeCdR) greater than 5-benzyloxymethyl-UdR (BOMeUdR). In a multistep virus replication experiment (plaque reduction assay on Vero cells) the order of decreasing activity was as follows: BrVUdR = ara-C greater than HMeUdR greater than fUdR IUdR greater than HMeCdR greater than BOMeUdR greater than AMeUdR greater than AIU greater than MMeUdR. BrVUdR effected a 50% reduction in plaque formation of different strains of HSV-1 at a concentration of 0.06-0.22 microM, of pseudorabies virus (PRV) at 0.02-0.23 microM, and of herpes simplex virus type 2 (HSV-2) at 8 microM, whereas the ID50 values for adenovirus type 2 and type 5 were 100 and 50-100 microM, respectively. The growth of synchronied baby hamster kidney cells in suspension cultures was inhibited by 50% at concentrations of 100, 70, 20, 4, 8, and 0.2 microM for BrVUdR, HMeCdR, IUdR, fUdR, BOMeUdR, and HMeUdR, respectively.

Adenoviruses, Simian↗
PubMed1982

Efficacy of (E)-5-(2-bromovinyl)-2'-deoxyuridine against different herpes simplex virus strains in cell culture and against experimental herpes encephalitis in mice.

(E)-5-(2-Bromovinyl-2'-deoxyuridine (BrVUdR) showed strong antiviral activity against different laboratory strains and clinical isolates of herpes simplex virus type 1 (HSV-1) on primary rabbit testes (PRT) cells with a 50% inhibition of plaque formation (ID50) at 0.01-0.02 microM. One laboratory strain (HSV-1-S), however, was completely refractory even at concentrations as high as 100 microM. In contrast, the ID50S for all herpes simplex virus type 2 (HSV-2) strains were about 10(2) - 10(3) times higher (8-25 microM) than for the HSV-1 strains. No toxicity in mice treated with 140 mg BrVUdR/kg/day for 14 days was observed, and successful treatments of herpes encephalitis in mice induced experimentally by intracerebral infection with one laboratory strain (HSV-1-Kupka) and one clinical isolate (HSV-1-64) were achieved. Treatment of encephalitis in mice induced by the strain HSV-1-S insensitive to BrVUdR in cell culture failed to be effective. Similar antibody titers against HSV-1 were found in surviving mice of the control and of the BrVUdR-treated groups.

Animals↗
PubMed1982

[Mathematical methods in flow cytometry: the problem of evaluating DNA histograms of partially synchronous cell populations].

There is presented a procedure for determining the phase fractions in a cell population (i.e. the fractions of the G1-, S- and G2 + M-cells) from the corresponding DNA histogram obtained by flow cytometry. The evaluation procedure can regard arbitrary apriori information about the model parameters. It is based on a mathematical model of the DNA distribution for a growing cell population which contains the phase fractions and some further values as parameters. The parameter estimations rest on the Maximum-Likelihood-Principle by which the parameters of the theoretical model must be determined in such a way that the measured histogram corresponds to a maximum probability. As a consequence of the model flexibility especially the S-phase fraction which can be determined independently by labeling techniques, can be regarded as a fixed predetermined value. Such apriori information enhances the preciseness of the parameter estimation. The applications have shown that the determination of the S-phase fraction by means of flow cytometry can be very unprecise especially under partial synchronization. For the application of the evaluation programs (programming language ALGOL) the histograms must be free of cell detritus and clumping.

Animals↗
PubMed1981

Synthesis of 6-substituted thymine nucleosides.

The preparation of several N(1)-glycosyl derivatives of 6-fluorothymine is described. The displacement of the fluorine atom at the C-6-position of the heterocyclic component lead to a series of new 6-substituted 5-methyl-pyrimidine-2,4-dione-nucleosides. Some of these new compounds show significant virostatic activity against influenza A virus strains.

Animals↗
PubMed1980

On a "chalone"-like factor for Ehrlich ascites mammary carcinoma.

In an aqueous ultrafiltrate (10 000--50 000) prepared from Ehrlich ascites mammary carcinoma (EAC) cells, ascites fluid and bovine mammary gland, a new factor was obtained which is involved in the growth regulating system of EAC cells as shown by the following facts: 1) It reversibly inhibits the proliferation of EAC cells in a 24 h suspension culture, depending on their proliferative state. Thus, stationary cells from the plateau phase of growth in vivo are prevented from resuming growth in vitro, while cells taken from the active phase of in vivo growth are not inhibited under the same conditions. Likewise, stationary cells do not respond when incubated in serum before the addition of the factor (depending on serum concentrations and time). The dose-response curve levels off at higher factor concentrations so that the maximal inhibition is about 50--65% (explained with different sensitivities of the cells in the assay system). The time course of the inhibition as well as preliminary data from flow cytophotometry and labeling with tritiated thymidine indicate an interference with the progression of G1-phase cells into the S-phase. 2) The activity of the factor is counteracted by insulin and proinsulin, both known as growth factors. The insulin concentration needed is dependent on the factor concentration; an almost maximal inhibition can be prevented by physiological concentrations of insulin. The activity can be destroyed by heat and trypsin and differs also in other properties from that of polyamines. The factor could not be detected in lung, liver, spleen, kidney, heart and L 1210 ascites fluid of the mouse or in bovine malignant lymph nodes, thymus, kidney or liver. The factor was purified from a homogenate of bovine mammary gland by ultrafiltration and affinity chromatography on sepharose-bound wheat lectin. Polyacrylamide electrophoresis showed about 5 bands of which one contained the activity (in some experiments overlapping with a second one). In this way a 800fold purification (starting from the ultrafiltrate) could be obtained. The overall purification (relative to the centrifuged homogenate) can be calculated to be more than 100 000 fold.

Animals↗
PubMed1979

Inhibition of proliferation of Ehrlich ascites carcinoma cells in vitro and in vivo by halogeno analogues of long chain acyl- and alkylglycerols.

A series of halogeno (chloro or fluoro) analogues of phospholipid precursors has been checked for their cytostatic activity both in vitro and in vivo. The compounds included monoacyl-, diacyl-, monoalkyldeoxyhalogenoglycerols and other acylhalogenoalkanols. Analogues of monoacylglycerols or monoalkylglycerols were found to have a strong inhibitory activity on the proliferation of Ehrlich ascites carcinoma cells in suspension culture. The compounds were also effective in vivo. Tolerable doses (e.g. 1/10 of the LD50) given i.p. only once on the first day after transplantation of EAC cells reduced the cell number on day 7 by 99% or increased the survival time about 4-fold. The in vivo efficacy or the ether derivatives was higher than that of the corresponding esters. However, most of the compounds so far investigated had no effect on the survival time or cell number after s.c. application. Moreover, there was no prolongation of the survival time of leukemia L1210 or L184 bearing mice. This shows that the systemic effects of most of the compounds are low and that they have to come into direct contact with tumour cells during application in order to be active. It is discussed whether theese compounds interfere more with the structure of the membrane than with membrane biosynthesis. However, at least in comparison to Tween 80 (which is of poorer cytostatic activity) they show only very low lytic effects on red blood cells.

Animals↗