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The effects of progesterone, dehydroepiandrosterone sulfate and 17β-estradiol on the synthesis and degradation of hyaluronate were investigated using human uterine cervix fibroblasts. The cells were incubated with [3H]glucosamine in the presence of the hormones and then [3H]hyaluronate was isolated from the medium. The changes in the radioactivity of [3H]hyaluronate showed that progesterone suppressed hyaluronate synthesis by 22% of the control levels, while dehydroepiandrosterone sulfate and 17β-estradiol enhanced it by 22% and 12% of the control levels, respectively. Furthermore, progesterone induced degradation of high-molecular-weight [14C]hyaluronate into low-molecular-weight hyaluronate (Mr≈40 000). These results suggest that in cultured fibroblasts from the human uterine cervix progesterone converts hyaluronate metabolism from the synthesis phase to the degradation phase.© 1997 Federation of European Biochemical Societies. All rights reserved

Ethylene control of anthocyanin formation functions only through light-initiated synthesis pathways of the rapid synthesis phase. Treatment with ethylene in the dark had no effect on dark anthocyanin synthesis in red cabbage (Brassica oleracea L.). Pretreatment of both red cabbage and sorghum (Sorghum vulgare L.) with ethylene for 24 hours in the dark did increase the rate of synthesis when the tissue was placed in the light. Light-initiated anthocyanin synthesis is inhibited by ethylene when the tissue is returned to the dark.

This paper presents a microcode generator, which accepts a source program (algorithm) and a target description (microarchitecture) as input and generates microcode to implement the algorithm on the defined microarchitecture. The target description is similar to the outputs produced by datapath synthesis phase in hardware design packages. Thus, it can be incorporated to synthesise a microprogrammed control. The microcode generator is based on an algorithm which preserves retargetability without sacrificing on design time. This is achieved by implementing the generator in two phases: in the first phase, a set of 'feasible' register transfer operations (called base-set) is generated from the microarchitecture description. In the second phase, translation is carried out by simply searching and matching the source program statements with the base-set.

Carbon-13 enrichment synthesis and incorporation into three important biological systems have been carried out to provide materials for carbon-13 magnetic resonance studies. These systems include antibody-labeled haptens, labeled t-RNA and 5S-RNA molecules, and pyridoxal-5'-phosphate-labeled substrate mixtures. The synthesis phase of the work has been completed in all three cases, and the NMR studies completed on all but the antibody-hapten system which is still in process having been absorbed into other supported projects. Publications are now in preparation for the RNA and pyridoxal work. Preliminary results on the antibody-haptens work are encouraging as signals of antibody absorbed haptens have been observed but the results are still not yet conclusive.

Meningiomas are common neoplasms in the central nervous system. Although most of these tumors are encapsulated and grow very slowly, some meningiomas invade into adjacent brain tissue and skull, grow faster, and recur more frequently than classic meningiomas. These malignant meningiomas, however, are not well defined histopathologically, and their biological characteristics have never been well documented. We studied the cell kinetics of human meningiomas immunohistochemically using a monoclonal antibody against bromodeoxyuridine (BUdR) (2), a thymidine analogue that is incorporated into nuclear DNA during the synthesis phase of the cell cycle. BUdR-labeled S-phase cells can be identified by anti-BUdR monoclonal antibodies, which can then be detected by indirect immunoperoxiase methods (3, 6).

THE duration of the ‘synthesis phase’ of deoxyribonucleic acid (DNA) of the mitotic cycle (phase S of Howard 19561 and Lajtha et al. 19542) has been determined for several cell types. As yet no distinction has been made between the uptake of labelled thymidine and its incorporation by the cell into a more complex structure, presumably DNA.

Synthesis phase of proliferating neurilemma cells in adult mouse sciatic nerve was studied during Wallerian degeneration. Its duration was found to be relatively constant (8.6–10.3 hours) and independent of variations in the neurilemma cell labeling index (0.8–15.5%). By the same technique, the duration of the synthesis phase in proliferating neurilemma cells in 2-day-old mouse sciatic nerve (10.5 hours) was roughly comparable to that during peripheral nerve degeneration in the adult mouse.

In eukaryotes, the cell cycle is driven by the actions of several cyclin dependent kinases (CDKs) and an array of regulatory proteins called cyclins, due to the cyclical expression patterns of the latter. In yeast, the accepted pattern of cyclin waves is based on qualitative studies performed by different laboratories using different strain backgrounds, different growing conditions and media, and different kinds of genetic manipulation. Additionally, only the subset of cyclins regulating Cdc28 was included, while the Pho85 cyclins were excluded. We describe a comprehensive, quantitative and accurate blueprint of G1 cyclins in the yeast Saccharomyces cerevisiae that, in addition to validating previous conclusions, yields new findings and establishes an accurate G1 cyclin blueprint. For the purposes of this research, we produced a collection of strains with all G1 cyclins identically tagged using the same and most respectful procedure possible. We report the contribution of each G1 cyclin for a broad array of growing and stress conditions, describe an unknown role for Pcl2 in heat-stress conditions and demonstrate the importance of maintaining the 3’UTR sequence of cyclins untouched during the tagging process. info:eu-repo/semantics/acceptedVersion

Replication fork stalling and accumulation of single-stranded DNA trigger the S phase checkpoint, a signalling cascade that, in budding yeast, leads to the activation of the Rad53 kinase. Rad53 is essential in maintaining cell viability, but its targets of regulation are still partially unknown. Here we show that Rad53 drives the hyper-SUMOylation of Pol2, the catalytic subunit of DNA polymerase ε, principally following replication forks stalling induced by nucleotide depletion. Pol2 is the main target of SUMOylation within the replisome and its modification requires the SUMO-ligase Mms21, a subunit of the Smc5/6 complex. Moreover, the Smc5/6 complex co-purifies with Pol ε, independently of other replisome components. Finally, we map Pol2 SUMOylation to a single site within the N-terminal catalytic domain and identify a SUMO-interacting motif at the C-terminus of Pol2. These data suggest that the S phase checkpoint regulate Pol ε during replication stress through Pol2 SUMOylation and SUMO-binding ability, Author summary Chromosome duplication is essential for cell proliferation. Mistakes during this process introduce mutations, duplications, deletions and rearrangements of the genetic information. Cells have evolved a monitoring pathway that supervises DNA replication, called S phase checkpoint; this regulates many aspects of the cell biology in response of defects during DNA replication, so to promote the complete and faithful completion of DNA replication once the obstacles are eliminated. While many details of the S phase checkpoint are known, how this pathway regulates the machine copying the DNA is still largely poorly understood. Here we present a novel mechanism of action of the S phase checkpoint preferentially observed in response to replication forks stalling. We show that the catalytic subunit of DNA Pol ε (Pol2), is the preferential target of modification with SUMO among the replication machinery components. This mono-SUMOylation depends on the S phase checkpoint factors Rad53, Mrc1 and Ctf18. Moreover, Pol ε is bound and SUMOylated by the Smc5/6 complex. Finally, we identified the site of the Pol2 modification and a SUMO binding-motif, suggesting a possible mechanism of action for this modification.

Objective: The purpose of this study is to analyze the perception of the content of health technology assessment (HTA) among health professionals applying for a state grant of DKK 10 million. Methods: A total of 113 applications were received and analyzed. When conducting the analysis, it was assumed that the applicants' maximum five-page project description would reflect: a) the applicants' perception of what an HTA is; b) how the assessment was to be conducted; and c) what the results were going to be used for. Results: More than 40% of all applications focused on treatment; in 51% only one or two professional groups were to be involved (thus interdisciplinarity was questionable); only 22% of the HTA cases were intended to form the basis for political/administrative decisions; in general, the HTAs were planned far less comprehensively than was relevant; 76% of the projects did not include a formal synthesis phase; 41% intended to use diffusion as the only method for publication of the HTA result. Conclusions: The analysis reveals several areas where DIHTA has to make an effort in order to secure that HTA in fact constitutes a comprehensive and well-documented basis for decision making. These areas concern the following topics: multidisciplinarity, the objective of HTA, comprehensiveness, the synthesis phase, and publication and utilization of the HTA result.

The thioredoxin and glutaredoxin pathways are responsible of recycling several enzymes which undergo intramolecular disulfide bond formation as part of their catalytic cycles such as the peroxide scavengers peroxiredoxins or the enzyme ribonucleotide reductase (RNR). RNR, the rate-limiting enzyme of deoxyribonucleotide synthesis, is an essential enzyme relying on these electron flow cascades for recycling. RNR is tightly regulated in a cell cycle-dependent manner at different levels, but little is known about the participation of electron donors in such regulation. Here, we show that cytosolic thioredoxins Trx1 and Trx3 are the primary electron donors for RNR in fission yeast. Unexpectedly, trx1 transcript and Trx1 protein levels are up-regulated in a G1-to-S phase-dependent manner, indicating that the supply of electron donors is also cell cycle-regulated. Indeed, genetic depletion of thioredoxins triggers a DNA replication checkpoint ruled by Rad3 and Cds1, with the final goal of up-regulating transcription of S phase genes and constitutive RNR synthesis. Regarding the thioredoxin and glutaredoxin cascades, one combination of gene deletions is synthetic lethal in fission yeast: cells lacking both thioredoxin reductase and cytosolic dithiol glutaredoxin. We have isolated a suppressor of this lethal phenotype: a mutation at the Tpx1-coding gene, leading to a frame shift and a loss-of-function of Tpx1, the main client of electron donors. We propose that in a mutant strain compromised in reducing equivalents, the absence of an abundant and competitive substrate such as the peroxiredoxin Tpx1 has been selected as a lethality suppressor to favor RNR function at the expense of the non-essential peroxide scavenging function, to allow DNA synthesis and cell growth., Author summary The essential enzyme ribonucleotide reductase (RNR), the rate-limiting enzyme of deoxyribonucleotide synthesis, relies on the thioredoxin and glutaredoxin electron flow cascades for recycling. RNR is tightly regulated in a cell cycle-dependent manner at different levels. Here, we show that cytosolic thioredoxin Trx1 is the primary electron donor for RNR in fission yeast, and that trx1 transcript and protein levels are up-regulated at G1-to-S phase transition. Genetic depletion of thioredoxins triggers the DNA replication checkpoint up-regulating RNR synthesis. Furthermore, deletion of the genes coding for thioredoxin reductase and dithiol glutaredoxin is synthetic lethal, and we show that a loss-of-function mutation at the peroxiredoxin Tpx1-coding gene acts as a genetic suppressor. We propose that in a mutant strain compromised in reducing equivalents, the absence of an abundant and competitive substrate of redoxins, the peroxiredoxin Tpx1, has been selected as a lethality suppressor to favor channeling of electrons to the essential RNR.

There are only few reports on p ro l i f e ra t ion k inet ics of renal ce l l carcinoma and the i r impl icat ions on survival of pat ients. In 105 pts.(76 male, 29 female; median age 59 years) we t r i ed to determine p ro l i f e ra t i on k inet ics by means of flowcytometry and in v i t r o autoradiography (double labe l l ing technique). Tumor specimen were invest igated 10-15 min. post operative removal. They were excised from the marginal and central areas of the primary tumor Results: Flowcytometry revealed a d ip lo id DNA d is t r ibu ~ 2 6 / I 0 5 patients (24%), hyperdiploid in 26/105 (24%), a hypodiploid in 4/105 (3,7%), a polyplo id in 38/105 (35%), a te t rap lo id in 4/I05 (3,7%), a hypertetraploid in 1/105 (0,9%), a hypotetraploid in 3/105 (2,8%), a~d an aneuploid d i s t r i bu t ion of DNA in 3/105 pat ients (2,8%). The labe l l ing index varied between 5 and 15%. The duration of DNS synthesis phase was between lO-2O hours. T~ere is no s ign i f i cant corre la t ion between ploidy of tumor cel l DNA and the h is to log ic pattern. There is a trend for higher labe l l ing indices in polyplo id ce l ls than in d ip lo id ones. 85% of pts who had no distant metastases at time of operation l i ve more than 3 years regardless of status of tumor cel l p lo idy. Patients with d is tant metastases at time of operation show s t a t i s t i ca l l y s ign i f i can t differences concerning surv iva l . Those with d ip lo id tumor cel l DNA have a median survival of 8,5 months compared with those having other status of ce l l p lo idy (4,5 months) In conclusion, the DNA d is t r ibu t ion pattern seems to be of importance as prognostic factor in pat ients with renal ce l l carcinoma.

In this paper the authors hypothesize that hierarchically differentiated groups will (1) exhibit less risk-taking behavior, (2) be less efficient, and (3) be less productive than hierarchically undifferentiated groups. To test the hypotheses, 10 hierarchically differentiated groups and 10 hierarchically undifferentiated groups formed from the staffs of 10 elementary schools were given a problem in logic. Results confirmed all three hypotheses at the analysis phase of problemsolving. Too few groups solved the problem to permit testing of the third hypothesis at the synthesis phase of problem solving. Edwin M. Bridges is associate professor of education at the University of Chicago; Wayne J. Doyle and David J. Mahan are research associates at Washington University, St. Louis.