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Biomedical subjects

J Fried

Publications and source records attributed to J Fried.

At least 55 records · Page 3Linked to original sources
PubMed1983

Bactobilin: blue bile pigment isolated from Clostridium tetanomorphum.

A blue bile pigment, possessing four acetic and four propionic acid side chains has been isolated from extracts of the anaerobic microorganism Clostridium tetanomorphum and in smaller amounts from Propionibacterium shermanii. The compound could be prepared in larger amounts by incubation of C. tetanomorphum enzyme extracts with added delta-aminolevulinic acid. The ultraviolet-visible, infrared, and proton magnetic resonance spectra of the pigment indicate a chromophore of the biliverdin type. Field-desorption mass spectrometry of the purified methyl ester showed a strong molecular ion at m/e = 962. This corresponds to the molecular weight expected for the octamethyl ester of a bilatriene type of bile pigment structurally derived from uroporphyrin III or I. Of the five possible structures, two could be eliminated by proton magnetic resonance spectroscopy. The name bactobilin is proposed for this previously unreported bile pigment.

Clostridium↗
PubMed1983

Factors modifying the synergistic toxicity of deoxycytidine in combination with thymidine plus 5-fluorouracil in HeLa cells.

We reported previously that deoxycytidine (CdR) enhances the cytotoxic effects of the drug combination thymidine (TdR) plus 5-fluorouracil (FUra) against HeLa S-3 cells. We have now examined the relationships between the concentration of CdR and its cytotoxic and cytokinetic effects, and have also investigated the role of certain other components of the culture medium in this phenomenon. Cell survival was determined by a colony-forming assay; cytokinetic effects were monitored by flow cytometry. In the initial experiments, cells were grown in Ham's F12 medium and exposed for 22 hr to 4 mM TdR, 0 X 025 mM FUra, and dCyd ranging from 1 microM to 4 X 0 mM. The individual drugs were at most only slightly toxic under these conditions; for TdR plus FUra, the survival decreased to 50% (in 5% FCS), and in the three-drug combination it varied from 8% at 1 microM CdR to 28% at 0 X 10 mM and back to a low of 3% at 4 X 0 mM CdR. Results from flow cytometry appeared correlated with the survival data, in that cells accumulated in the S phase to a greater extent in the region around 0 X 10 mM CdR than at higher or lower concentrations. When cells were exposed to the drugs in MEM medium in place of F12, their sensitivity to FUra and the TdR-FUra combination was enhanced, although the additional synergistic effect of CdR was reduced. We found that hypoxanthine, present in F12 but not in MEM, was the principal compound responsible for the observed differences between media.

Cell Survival↗
PubMed1982

Effects of Hoechst 33342 on survival and growth of two tumor cell lines and on hematopoietically normal bone marrow cells.

Our objective in this investigation was to determine whether Hoechst 33342, which is widely recognized as a DNA specific fluorochrome for living cells, is in fact nontoxic and kinetically nonperturbing at dye concentrations required to achieve acceptable DNA distributions. Three cell types were tested: HeLa S-3; SK-DHL2, a human lymphoma cell line; and hematopoietically normal human bone marrow cells. In the third system, only the cloning efficiencies were determined. Results differed considerably for the different cell types. While HeLa cells yielded excellent DNA distributions and were almost completely resistant to the cytotoxic and cytokinetic effects of the dye, SK-DHL2 cells were highly sensitive to the fluorochrome even at dye concentrations which produced very poor DNA distributions. Human bone marrow cells were intermediate in their stainability and toxicity response, and acceptable DNA distributions could be obtained at the nontoxic dye concentration of 2.5 muM. Clearly, different cell types differ considerably with respect to their cytotoxic and kinetic responses to Hoechst 33342. In some cases it may not be possible to ensure adequate staining of the cells for flow cytometry without significantly altering their viability and/or proliferative behavior.

Benzimidazoles↗
PubMed1982

Effects of cytosine arabinoside and daunorubicin on survival and cell cycle progression of Chinese hamster ovary cells.

Kinetic and cytotoxic effects of cytosine arabinoside (Ara-C) and daunorubicin (DNR) on exponentially growing Chinese hamster ovary (CHO) cells were measured by flow cytometry and by a colony-forming assay, respectively. With Ara-C alone, increasing drug concentrations between 10(-7) M and 10(-4) M, for up to 27 hr, were associated with increased inhibition of cell progression through the S phase. Even at the very toxic concentration of 10(-4) M, however, cells were able to enter and progress slowly through S. DNR, which appears to enter these cells relatively slowly, was highly toxic even at 2 X 10(-7) M. It decreased the rate of progression through S phase and caused cells to accumulate in G2, except at the highest concentration (2 X 10(-5) M, at which progression was inhibited throughout the cycle. Simultaneous exposure of the cells to Ara-C and DNR yielded cell cycle distributions similar to those of the former drug alone. When cells were exposed to a non-lethal dose of Ara-C and to a dose of DNR which was lethal to a fraction of the cell population (or conversely), either simultaneously or separated by a drug-free interval, small, but in some cases significant, drug interactions were observed. These effects were not caused by drug-induced redistribution of cells within the cell cycle, but may have been related to the effects of the non-lethal drug on DNA synthesis rate.

Animals↗
PubMed1982

A comparison of mathematical methods for the analysis of DNA histograms obtained by flow cytometry.

Twelve methods for analysing FCM-histograms were compared using the same set of data. Some of the histograms that were analysed were simulated by computer and some were taken from experiments. Simulated data were generated assuming synchronously growing cell populations and (i) measurement coefficients of variation (CV) from 2 to 16%; (ii) constant measurement CV or VC's increasing from G1 to G2 phase, and (iii) varying fractions of cells in each phase. Simulated data were also generated assuming synchronous cell populations in which a block in early S phase was applied and released. DNA histograms were measured for L-929 cells at various times after mitotic selection. Labelling indices were also measured for these cells at the same time. The fractions of cells in the G1, S, and (G2 + M) phases were calculated by each analytical method and compared with the actual fractions used for simulation, or in case of experimental data, with autoradiographic results. Generally, all methods yielded reasonably accurate fractions of cells in each phase with relative errors in the range of 10-20%. However, most methods tended to overestimate G1 fractions and underestimate S fractions. In addition, variations in the shape of the S phase distribution often caused considerable errors. Phase fractions were also calculated for histograms of kinetically perturbed populations, simulated as well as experimental. The errors were only slightly larger than for histograms from asynchronously growing cell populations.

Analysis of Variance↗
PubMed1981

Relative contracting and relaxing potencies of a series of prostaglandins on isolated canine mesenteric artery strips.

The contracting and relaxing potencies of and interactions between a number of prostaglandins (PGs) were studied in vitro on spiral strips of small canine mesenteric arteries (outside diameter less than 1 mm). PGF2 alpha and PGE2, the most potent contracting PGs, were nearly equal in potency (EC50 4 x 10(-7) M) and did not cause relaxation under our experimental conditions. PGI2 and PGE1 were equal and the most potent relaxing PGs (EC50 3 x 10(-9) M). PGE1 also caused contraction, but this effect was not consistent. PGI2 did not cause contraction in concentrations up to 3 x 10(-6) M. In higher concentrations, however, it caused abrupt and near maximal contraction. PGD2 was weak in both respects, causing incomplete relaxation and contraction or biphasic effects. Interaction studies showed that PGE1 and PGI2 mutually excluded the relaxing effects of each other. PGE1 also reversed the relaxing effect of isoproterenol. However, pre-exposure to PGD2 did not attenuate the relaxing effect of PGE1 or PGI2 nor was the relaxing effect of PGD2 changed by pre-exposure to PGE1. Two different orders of potency of PGs suggest two PG receptors subserving contraction and relaxation, respectively. Further, it appears that several PGs can act upon both receptors which may explain unusual interactions between the PGs and some of their atypical effects. Finally, the data also suggest that there may be subtypes of the PG receptors subserving contraction and relaxation.

Animals↗
PubMed1981

Hallucinations and delusions in black psychiatric patients.

A higher incidence of hallucinations has been previously reported among blacks, as compared to whites, in both psychiatric and nonpsychiatric populations. In contrast to these reports, which relied on hospital records, the present study utilized standardized research rating scales, and confirmed the above observation among schizophrenic patients. Some blacks, irrespective of diagnosis, probably experience a variety of non-schizophrenic hallucinations, may lead to erroneous diagnoses of schizophrenia. Current ignorance regarding the content of hallucinations in normal and non-schizophrenic, and in schizophrenic blacks is a source of diagnostic confusion which may have dire consequences for many individuals.

Adult↗
PubMed1981

Cytotoxic and cytokinetic effects of thymidine, 5-fluorouracil, and deoxycytidine on HeLa cells in culture.

Exponentially growing HeLa cells were exposed to thymidine (dThd), 5-fluorouracil (FUra), and deoxycytidine (dCyd) singly and in combination for up to 3 days. Survivals were measured using a colony forming assay, and cytokinetic effects of the drugs were evaluated by flow cytometry and by determination of population growth rates. Increasing concentrations of dThd alone (up to 4 mM) progressively slowed the movement of cells through the cycle; dThd was toxic above 1 mM. Nontoxic levels of FUra (10(-5) M) inhibited cell progression, but this was abolished by very low concentrations (3 microM) of dThd. The cytotoxic effects of FUra were not reversed by dThd; in fact, the lethality of FUra was enhanced in some cases. dCyd alone had neither cytotoxic nor cytokinetic effects on HeLa cells up to 4 mM, but low concentrations reversed the cytotoxic effects of 4 mM dThd and high concentrations reversed its cytokinetic effects. When dCyd was added to the combination of dThd and FUra, synergistic lethality resulted even at 10(-5) M FUra. The mechanism by which this synergism was achieved was not simply increased incorporation of FUra into RNA since, while dThd did enhance this incorporation, dCyd did not further increase it. Our results suggest instead that dCyd either directly or indirectly inhibited the repair of FUra-associated damage or else enabled the cells to progress into a more sensitive phase of the cell cycle during exposure.

Cell Division↗
PubMed1981

Cytotoxic and cytokinetic effects of 1-beta-D-arabinofuranosylcytosine, daunorubicin, and 6-thioguanine on HeLa cells in culture.

Exponentially growing HeLa cells were exposed to 1-beta-D-arabinofuranosylcytosine, daunorubicin, and 6-thioguanine singly and in combination for 21 hr. Survivals were determined by a colony-counting assay, and cytokinetic effects of the drugs were evaluated by flow cytometry. When used in two-drug combinations (concurrent exposures). 1-beta-D-arabinofuranosylcytosine was found to protect cells against both 6-thioguanine- and daunorubicin-induced lethality, the former to a greater extent than the latter. Protection against 6-thioguanine appeared to be related to the degree of inhibition of DNA synthesis by 1-beta-D-arabinofuranosylcytosine, but this was not the case with daunorubicin. When cells were exposed to the three drugs simultaneously, survivals were in agreement with those predicted from the various two-drug combinations. This implies that no additional drug interactions occurred when a third drug was added to the two-drug combinations.

Cell Cycle↗
PubMed1980

Inhibition of platelet aggregation and elevation of cyclic-AMP levels in platelets by 13,14-dehydro PGI2 methyl ester.

13,14-Dehydro PGI2 (dh-PGI2) and 13,14-dehydro PGI2 methyl ester (dh-PGI2-Me) inhibited platelet aggregation and release of [14C]-serotonin and ADP induced by collagen, ADP, arachidonic acid and PGG2. The inhibitory dose (ID50) ofg dh-PGI2-Me on platelet aggregation was 3 x 10(-9)M when induced with collagen, 2 x 10(-8) M with ADP, 5 x 10(-9) M with arachidonic acid and 1 x 10(-8)M with PGG2. The effects of dh-PGI2 and dh-POGI2-Me on platelet aggregation appear to be mediated by cyclic AMP, since both agents were potent to stimulate platelet cyclic AMP formation. In this respect dh-PGI2-Me was more effective than dh-PGI2 and PGE1. The actions of dh-PGI2-Me on platelet aggregation reported in this study suggest that is posseses similar biological properties as natural PGI2. Since dh-PGI2-Me is considerably more stable at physiological pH than PGI2 (Fried, J. and Barton, J. (1977) Proc. Natl. Acad. Sci. USA, 74, 2199-2203) this PGI2 analog might be useful as an anti-thrombotic drug.

Adenosine Diphosphate↗
PubMed1980

Vascular relaxing activity and stability studies of 10,10-difluoro-13,14-dehydroprostacyclin.

10,10-Difluoro-13,14-dehydroprostacyclin was compared with natural prostacyclin (prostaglandin I2, PGI2) for vascular relaxing activity in vitro on helical strips of small canine mesenteric arteries (outside diameter < 1 mm) and bovine coronary arteries (outside diameter 1.5-2.5 mm) partially contracted with prostaglanding F2 alpha as well as in vivo in pentobarbital-anesthetized dogs. The difluoro analog was 3- to 4-fold more active than PGI2 in causing relaxation of both types of strips and appeared at least equipotent to PGI2 in its blood pressure lowering effect in dogs. When incubated with Krebs' bicarbonate solution (pH 7.4) at 37 degrees C, the biological half-life of the difluoro analog was about 24 hr compared to the 10- to 15-min half-life of PGI2 under similar conditions. However, when administered intravenously to dogs, the hemodynamic effects of the difluoro analog were of the same duration as those of PGI2.

Animals↗
PubMed1980

Comparative luteolytic effects of prostaglandin F2 alpha and its 13-dehydro analogs in vivo.

Several 13-dehydro analogs were shown to be luteolytic in both the cyclic sheep and cyclic primate models studied. The fact that these luteolytic analogs have diminished uterine smooth muscle activity suggests that the receptors governing the smooth muscle effect on the one hand, and the luteolytic effect on the other, may possess different structural specificities. In both species studied, the analogs showed marked resistance to the PG-15-OH-dehydrogenase in vivo as shown by their activity when infused intravenously. In the early pregnant monkey, the reduced luteolytic activity of the 13-dehydro analogs suggests that mCG may have a protective effect on the corpus luteum to PGs in general. Thus, the early pregnant monkey, or possibly the hCG-treated cyclic monkey, would appear to be "essential" models in the study of luteolytic agents in the primate. Finally, previous reports of termination of early pregnancy in monkeys with luteolytic PG analogs may have depended, at least in part, on their intrinsic smooth muscle activity on the uterus.

Animals↗