Relationship between Machiavellianism and External Control among Italian Undergraduates

148 Italian undergraduates (62 men and 86 women) responded to the Italian version of the Christie's Mach IV scale and to the Italian version of the Rotter's Internal-External (I-E) Control scale. The positive correlation between Machiavellianism and external locus of control of .40 was significant for men as well as for women. The results confirm previous findings that more external individuals tend to agree with Machiavellian positions than do internal persons. The implications of the findings were discussed.

Note: An analyzer for field detection of H2S by using cavity ring-down at 1.57 μm

A prototype analyzer for the detection of hydrogen sulfide (H2S), based on cavity ring-down spectroscopy, is described. The device exploits, whenever possible, optical fibers, in order to simplify the alignment and to improve the stability. A trade-off between low detection level and simplicity has been pursued. The experimental results obtained during tests on different kinds of H2S samples are shown.

Mid-infrared frequency comb for broadband high precision and sensitivity molecular spectroscopy

We report on the experimental demonstration of the metrological and spectroscopic performances of a mid-infrared comb generated by a nonlinear downconversion process from a Ti:sapphire-based near-infrared comb. A quantum cascade laser at 4330 nm was phase-locked to a single tooth of this mid-infrared comb and its frequency-noise power spectral density was measured. The mid-infrared comb itself was also used as a multifrequency highly coherent source to perform ambient air direct comb spectroscopy with the Vernier technique, by demultiplexing it with a high-finesse Fabry-Perot cavity.

High-coherence mid-infrared frequency comb

We report on the generation of a frequency comb around 4330 nm with an unprecedented coherence of the single teeth. Generating the comb within a Ti:sapphire laser cavity by a difference-frequency process and using a phase-lock scheme based on direct digital synthesis, we achieve a tooth linewidth of 2.0 kHz in a 1-s timescale (750 Hz in 20 ms). The generated per-tooth power of 1 μW ranks this comb among the best ever realized in the mid-infrared in terms of power spectral density.

Direct link of a mid-infrared QCL to a frequency comb by optical injection

A narrow-linewidth comb-linked nonlinear source is used as master radiation to injection lock a room-temperature mid-infrared quantum cascade laser (QCL). This process leads to a direct lock of the QCL to the optical frequency comb, providing the unique features of narrow linewidth, absolute frequency, higher output power, and wide mode-hop-free tunability. The QCL reproduces the injected radiation within more than 94%, with a reduction of the frequency-noise spectral density by 3 to 4 orders of magnitude up to about 100 kHz, and a linewidth narrowing from a few MHz to 20 kHz.

Molecular gas sensing below parts per trillion: radiocarbon-dioxide optical detection

Radiocarbon ((14)C) concentrations at a 43 parts-per-quadrillion level are measured by using saturated-absorption cavity ringdown spectroscopy by exciting radiocarbon-dioxide ((14)C(16)O(2)) molecules at the 4.5 μm wavelength. The ultimate sensitivity limits of molecular trace gas sensing are pushed down to attobar pressures using a comb-assisted absorption spectroscopy setup. Such a result represents the lowest pressure ever detected for a gas of simple molecules. The unique sensitivity, the wide dynamic range, the compactness, and the relatively low cost of this table-top setup open new perspectives for ^{14}C-tracing applications, such as radiocarbon dating, biomedicine, or environmental and earth sciences. The detection of other very rare molecules can be pursued as well thanks to the wide and continuous mid-IR spectral coverage of the described setup.

Measuring frequency noise and intrinsic linewidth of a room-temperature DFB quantum cascade laser

The frequency-noise power spectral density of a room-temperature distributed-feedback quantum cascade laser emitting at λ = 4.36 μm has been measured. An intrinsic linewidth value of 260 Hz is retrieved, in reasonable agreement with theoretical calculations. A noise reduction of about a factor 200 in most of the frequency interval is also found, with respect to a cryogenic laser at the same wavelength. A quantitative treatment shows that it can be explained by a temperature-dependent mechanism governing the transport processes in resonant tunnelling devices. This confirms the predominant effect of the heterostructure in determining shape and magnitude of the frequency noise spectrum in QCLs.

Ti:sapphire laser intracavity difference-frequency generation of 30 mW cw radiation around 4.5 μm

A cw mid-IR coherent source based on difference-frequency generation is designed and characterized. For mid-IR generation, a periodically poled MgO:LiNbO(3) crystal is placed inside a compact Ti:sapphire laser cavity. This provides high-power pump radiation for the nonlinear process. Optical injection by an external-cavity diode laser ensures single-frequency operation of the Ti:sapphire laser, while signal radiation is provided by a fiber-amplified Nd:YAG laser. Mid-IR radiation can be generated with 3850-4540 nm tuning range, narrow linewidth, Cs-standard traceability, and TEM(00) spatial mode. 30 mW power is obtained at 4510 nm.

Saturated-absorption cavity ring-down spectroscopy

We report on a novel approach to cavity ring-down spectroscopy with the sample gas in saturated-absorption regime. This technique allows us to decouple and simultaneously retrieve the empty-cavity background and absorption signal, by means of a theoretical model that we developed and tested. The high sensitivity and frequency precision for spectroscopic applications are exploited to measure, for the first time, the hyperfine structure of an excited vibrational state of 17O12C16O in natural abundance with an accuracy of a few parts in 10{-11}.

Observing the intrinsic linewidth of a quantum-cascade laser: beyond the Schawlow-Townes limit

A comprehensive investigation of the frequency-noise spectral density of a free-running midinfrared quantum-cascade laser is presented for the first time. It provides direct evidence of the leveling of this noise down to a white-noise plateau, corresponding to an intrinsic linewidth of a few hundred hertz. The experiment is in agreement with the most recent theory on the fundamental mechanism of line broadening in quantum-cascade lasers, which provides a new insight into the Schawlow-Townes formula and predicts a narrowing beyond the limit set by the radiative lifetime of the upper level.

Ultra-stable, widely tunable and absolutely linked mid-IR coherent source

We report on a new coherent source that, using a phase-lock scheme to an optical frequency-comb synthesizer, achieves a 10-Hz intrinsic linewidth, is tunable from 4 to 4.5 microm with a presettable absolute frequency and, when coupled to a high-finesse cavity, can provide a short-term absorption sensitivity of 1.3 x 10(-11) cm(-1)Hz,(-1/2). These unique spectral features make this source a precise tool for molecular physics.

Lamb-dip-locked quantum cascade laser for comb-referenced IR absolute frequency measurements

The frequency of a DFB quantum cascade laser (QCL) emitting at 4.3 microm has been long-term stabilized to the Lamb-dip center of a CO2 ro-vibrational transition by means of first-derivative locking to the saturated absorption signal. Thanks to the non-linear sum-frequency generation (SFG) process with a fiber-amplified Nd:YAG laser, the QCL mid-infrared (IR) radiation has been linked to an optical frequency-comb synthesizer (OFCS) and its absolute frequency counted with a kHz-level precision and an overall uncertainty of 75 kHz.

Animal performance and meat quality in cull cows with early weaned calves in Argentina

Early weaning of calves (60 days old) is adopted in cow-calf operations for its high reproductive response. The objective of this research work was to find how age classes are related to beef quality in early weaning cull cows. Twenty four cows were grouped in four different age classes (teeth and number of calves produced) from two teeth and no calf produced, up to 12 years and 7 calves produced. All cows grazed a perennial pasture based on alfalfa and fescue. There were differences (P<0.05) in final weight (younger cows being lighter) but no other differences could be found during field conditions or in abattoir data (carcass weight and yield, top value hindquarter cuts weight and carcass percent). No differences (P>0.05) could be found in meat quality attributes except for moisture, protein and fat yellowness. Differences (P<0.05) in sensory attributes could only be found in connective tissue.

Frequency-comb-referenced quantum-cascade laser at 4.4 microm

We report what we believe to be the first absolute frequency measurement performed using a quantum-cascade laser (QCL) referenced to an optical frequency comb synthesizer (OFCS). A QCL at 4.43 microm has been used for producing near-infrared radiation at 858 nm by means of sum-frequency generation with a Nd:YAG source in a periodically poled lithium niobate nonlinear crystal. The absolute frequency of the QCL source has been measured by detecting the beat note between the sum frequency and a diode laser at the same wavelength, while both the Nd:YAG and the diode laser were referenced to the OFCS. Doppler-broadened line profiles of (13)CO(2) molecular transitions have been recorded with such an absolute frequency reference.

Aerodynamic findings in esophageal voice

OBJECTIVE

To define the perceptive and aerodynamic characteristics of esophageal voice in relation to different rehabilitation modalities.

DESIGN

Cross-sectional study comparing perceptive and aerodynamic variables in 3 subject groups.

SETTING

Referral center.

SUBJECTS

A total of 19 subjects who underwent total laryngectomy were divided into groups A and B. Group A consisted of 13 subjects (who required speech therapy)-8 good speakers (subset A(1) who were >80% intelligible) and 5 mediocre speakers (subset A(2) who were <70% intelligible). Group B consisted of 6 subjects with a tracheoesophageal prosthesis (who were >90% intelligible).

MAIN OUTCOME MEASURES

Perceptive variables included phonatory pauses and stomal noise. Aerodynamic variables included maximum phonation time, phonatory flow, phonatory volume, postphonatory volume, intensity, and articulatory pressure.

RESULTS

Phonatory pauses and stomal noise statistically differentiated group A from group B and good speakers from mediocre speakers. Phonation time, phonatory volume, and phonatory flow were statistically higher in group B subjects compared with group A subjects. Postphonatory volume was significantly higher in group A. Intraoral pressure and postphonatory volume were statistically higher in subset A(2) subjects compared with subset A(1) subjects while maximum phonation time was significantly higher in subset A(1) subjects compared with subset A(2) subjects.

CONCLUSIONS

In subset A(1) subjects a positive ratio between phonatory volume and phonatory flow was maintained with an adequate phonation time. In subset A(2) subjects a reduced phonatory volume was associated with a more rapid dispersion of phonatory flow, lower duration of phonation, and frequent pauses; stomal noise and consonant hyperarticulation worsened the voice performance in this group. In group B subjects the positive ratio between phonatory volume and phonatory flow represented the prerequisite of speech without frequent pauses.

MSSP, a protein binding to an origin of replication in the c-myc gene, interacts with a catalytic subunit of DNA polymerase alpha and stimulates its polymerase activity

MSSP has been identified as a protein that binds to both single- and double-stranded sequences of a putative DNA replication origin sequence in the human c-myc gene. MSSP possesses versatile functions, including stimulation of DNA replication, transcriptional regulation, apoptosis induction, and cell transformation coordinated by c-Myc. MSSP contains two RNP domains, RNP1-A and RNP1-B, both of which are necessary for all of the functions of MSSP. In this study, we found that MSSP binds to the N-terminal region of a catalytic subunit of a human DNA polymerase alpha via its RNP domains both in vitro and in human cells. Furthermore, MSSP was released from the putative DNA replication origin of the c-myc gene after it complexed with DNA polymerase alpha, and MSSP stimulated DNA polymerase activity in vitro.

Paclitaxel efficacy and tolerability in second-line treatment of refractory and relapsed ovarian cancer patients

Nineteen patients with recurrent or refractory ovarian carcinoma after a first-line platinum-based chemotherapy were treated with a 3-hour i.v. infusion of paclitaxel 175 mg/m2 every 3 weeks from November 1992 to October 1996. The major hematologic toxicity was neutropenia (63.2%). No febrile neutropenia was observed. Other hematologic effects were leukopenia (47.4%) and anemia (47.4%). The main non-hematologic toxicities were as follows: neuropathy (52.6%), nausea and vomiting (36.8%), myalgia (36.8%), cardiac toxicity (15.8%) and mucositis (10.5%). Alopecia was observed in the majority of cases. The overall response rate was 47.4%, with 5 (26.3%) complete responses (CRs) and 4 (21.1%) partial responses (PRs). The median duration of response was 7 months (range: 3-19), with a median follow-up of 17 months (range: 3-61). Quality of life of responding patients was good. Our results confirm that paclitaxel as second-line therapy in relapsed and refractory ovarian cancer patients is an acceptable treatment with a good safety profile, and can be safely administered at the dose of 175 mg/m2. In our study paclitaxel was more active in relapsed than in refractory patients. Consequently, further studies are needed to identify more effective drugs for the refractory subset.

The use of dynamic posturography to detect neurosensorial disorder in IDDM without clinical neuropathy

The main aim was to evaluate the relative importance of sensory interactions for postural stability in 45 patients with insulin-dependent diabetes mellitus (IDDM) with and without peripheral neuropathy. All subjects had normal electronystagmography. Dynamic posturography provides functional, selective testing of three sensory modalities in maintenance of balance, i.e., vestibular, visual, and somatosensory. The Sensory Organization Test (SOT) includes six test conditions during which the subject tries to maintain an upright stance with as little sway as possible. The subject stands on a movable platform facing a square visual surrounding, which can be rotated independently. The test is performed first with the eyes open, then with the eyes closed. The second component of posturography testing consists of the Motor Control Test (MCT) concerning motor responses routinely used in balance maintenance. Compared to control subjects, IDDM patients with peripheral neuropathy but not patients without neuropathy showed lower scores for test conditions SOT 1 (analysis of variance, ANOVA F = 8.3; Scheffe test: p = 0.0007), SOT 2 (F = 6.6; p = 0.004), SOT 3 (F = 3.4; p = 0.04), and SOT 6 (F = 3.4; p = 0.04). The muscle response latencies in MCT were prolonged for small forward perturbations (F = 4.6; p = 0.02) in neuropathic patients (148.3+/-14.2 ms) with respect to control subjects, but not in non-neuropathic patients with respect to control subjects (135.2+/-13.3 ms). Sural (r = 0.2; p = 0.002) and peroneal (r = 0.12; p = 0.02) nerve conduction velocities showed significant correlations with muscle response latencies of MCT for small forward perturbations. Our results suggest a subclinical dysequilibrium in IDDM patients with peripheral neuropathy. The results of dynamic posturography may reflect the impairment of the somatosensory system, rather than a specific lesion of vestibular and/or visual modalities.

Cortisol increases transfection efficiency of cells

DNA uptake can be facilitated by addition of physiological amounts of 11beta-hydroxy glucocorticosteroids (such as cortisol) during transfection. In the presence of cortisol, but not of the inactive 11-keto glucocorticoid cortisone, twice as many cells uptake and express the reporter gene. The effect is specific and dose-dependent; the amounts of glucocorticosteroids needed to enhance transfection efficiency are in the nanomolar range, which corresponds to the dissociation constant of glucocorticoids for the glucocorticoid receptor in vitro. This effect can be abolished by an excess of the glucocorticoid antagonist RU486. We infer that the activated cytoplasmic glucocorticoid receptors enhance nuclear translocation of the incoming transfected DNA.

DNA replication and order of cell cycle events: a role for protein isoprenylation?

When the aya1+ gene is mutated, Schizosaccharomyces pombe cells become unable to react appropriately to a delay in DNA replication. Instead of stalling the cell cycle to allow completion of DNA synthesis, they proceed unperturbed towards mitosis and attempt to segregate the still unreplicated chromosomes. As a result, the genetic material segregates unevenly and the nuclei assume a mitotic catastrophe phenotype, characterized by torn chromosomes (cut), anucleated cells and scattered chromosomes. Interestingly, the aya1 phenotype can be suppressed by overexpression of either the catalytic subunit of S. pombe DNA polymerase alpha or of a novel protein called hur1 +p. The latter bears significant homology to the core of the human Rab escort protein, which belongs to a family of factors necessary to the post-translational isoprenylation of proteins like Ras, Rab and lamin B. When isoprenylation is chemically inhibited with R-limonene (a monoterpene derived from orange rind), wild type S. pombe cells become insensitive to an S phase delay, in a manner strongly reminiscent of aya1 mutants. Moreover, overexpression of hur1 +p in wild type cells rescues the failing checkpoint function. We propose that there is a strong correlation between the aya1 phenotype, S-M phase checkpoint function, and isoprenylation events in fission yeast.

Tumor necrosis factor alpha and interleukin 1beta enhance the cortisone/cortisol shuttle

Endogenously released or exogenously administered glucocorticosteroids are relevant hormones for controlling inflammation. Only 11beta-hydroxy glucocorticosteroids, but not 11-keto glucocorticosteroids, activate glucocorticoid receptors. Since we found that glomerular mesangial cells (GMC) express 11beta-hydroxysteroid dehydrogenase 1 (11beta-OHSD1), which interconverts 11-keto glucocorticosteroids into 11beta-hydroxy glucocorticosteroids (cortisone/cortisol shuttle), we explored whether 11beta-OHSD1 determines the antiinflammatory effect of glucocorticosteroids. GMC exposed to interleukin (IL)-1beta or tumor necrosis factor alpha (TNF-alpha) release group II phospholipase A2 (PLA2), a key enzyme producing inflammatory mediators. 11beta-hydroxy glucocorticosteroids inhibited cytokine-induced transcription and release of PLA2 through a glucocorticoid receptor-dependent mechanism. This inhibition was enhanced by inhibiting 11beta-OHSD1. Interestingly, 11-keto glucocorticosteroids decreased cytokine-induced PLA2 release as well, a finding abrogated by inhibiting 11beta-OHSD1. Stimulating GMC with IL-1beta or TNF-alpha increased expression and reductase activity of 11beta-OHSD1. Similarly, this IL-1beta- and TNF-alpha-induced formation of active 11beta-hydroxy glucocorticosteroids from inert 11-keto glucocorticosteroids by the 11beta-OHSD1 was shown in the Kiki cell line that expresses the stably transfected bacterial beta-galactosidase gene under the control of a glucocorticosteroids response element. Thus, we conclude that 11beta-OHSD1 controls access of 11beta-hydroxy glucocorticosteroids and 11-keto glucocorticosteroids to glucocorticoid receptors and thus determines the anti-inflammatory effect of glucocorticosteroids. IL-1beta and TNF-alpha upregulate specifically the reductase activity of 11beta-OHSD1 and counterbalance by that mechanism their own proinflammatory effect.

A novel mutant allele of Schizosaccharomyces pombe rad26 defective in monitoring S-phase progression to prevent premature mitosis

A semipermissive growth condition was defined for a Schizosaccharomyces pombe strain carrying a thermosensitive allele of DNA polymerase delta (pol delta ts03). Under this condition, DNA polymerase delta is semidisabled and causes a delay in S-phase progression. Using a genetic strategy, we have isolated a panel of mutants that enter premature mitosis when DNA replication is incomplete but which are not defective for arrest in G2/M following DNA damage. We characterized the aya14 mutant, which enters premature mitosis when S phase is arrested by genetic or chemical means. However, this mutant is sensitive to neither UV nor gamma irradiation. Two genomic clones, rad26+ and cds1+, were found to suppress the hydroxyurea sensitivity of the aya14 mutant. Genetic analysis indicates that aya14 is a novel allele of the cell cycle checkpoint gene rad26+, which we have named rad26.a14. cds1+ is a suppressor which suppresses the S-phase feedback control defect of rad26.a14 when S phase is inhibited by either hydroxyurea or cdc22, but it does not suppress the defect when S phase is arrested by a mutant DNA polymerase. Analyses of rad26.a14 in a variety of cdc mutant backgrounds indicate that strains containing rad26.a14 bypass S-phase arrest but not G1 or late S/G2 arrest. A model of how Rad26 monitors S-phase progression to maintain the dependency of cell cycle events and coordinates with other rad/hus checkpoint gene products in responding to radiation damage is proposed.

Identification and cDNA cloning of single-stranded DNA binding proteins that interact with the region upstream of the human c-myc gene

We have previously reported that a c-myc protein complex binds to the region upstream of the c-myc gene, where exist an origin of cellular DNA replication (ori) and a transcriptional enhancer. Both functions require a 21 bp long sequence, while the c-myc protein complex recognizes a 7 bp consensus therein. It was recently reported that single-stranded DNA binding proteins bound specifically to sequences that play roles in DNA replication or transcription. We examined for proteins binding to the single-stranded DNAs of the 21 bp element (myc(H-P)21). In a band shift assay with HL60 cells nuclear extract, probes of either the plus strand or the minus strand gave rise to specific signals. Mutation introduced within a short consensus (A/TCTA/TA/TT) present in both strands completely abolished binding in either case. Southwestern blotting analysis showed that proteins of molecular weight 105, 80, 50, 45, 40, 39.5 and 14 kDa bound sequence-specifically to either strand and 22 kDa to minus strand to the cognate A/TCTA/TA/TT consensus. These single-stranded DNA binding proteins were named MSSP, c-myc gene single strand binding proteins. We attempted to isolate the cDNAs encoding these proteins by screening a human cDNA library with the plus single-stranded oligonucleotide as a probe. Among several positive clones, we have characterized one, termed MSSP-1. MSSP-1 produced in E. coli as a fusion protein with GST specifically interacted with single-stranded TCTTAT (plus myc(H-P)21) and ACT-ATT (in minus myc(H-P)21), the consensus of which can be referred to as A/TCTA/TA/TT. Sequence analysis of MSSP-1 cDNA revealed that two domains thereof are homologous to the RNA binding motifs common to several ribonucleoproteins. Interestingly, the MSSP-1/GST fusion protein specifically recognized myc(H-P)21 not only in single-stranded but also in double-stranded forms. Binding properties of MSSP-1 imply its functions in DNA replication. Furthermore, when the AT stretch in the SV40 ori core was substituted by TCTTAT, MSSP-1 promoted viral DNA replication depending on the consensus sequences.

Cell cycle-dependent activation of C-myc enhancer

The cellular oncogene c-myc encodes a nuclear protein that is considered to play a role in cell proliferation. In this report, the region upstream from the transcriptional promoter of the c-myc gene was examined for regulatory activity on its expression during cell cycle. Plasmids which contain the upstream region of human c-myc gene linked to the bacterial chloramphenicol acetyltransferase (CAT) gene were transfected to rat 3Y1 cells together with pSV2Hg (containing the hygromycin resistance gene linked to the SV40 promoter). Stably transformed cell lines were obtained by hygromycin selection. In random culture, the cells possessing CAT gene preceeded by the upstream region of the c-myc gene, including the HindIII-PstI [myc(H-P)] region, showed strong CAT activity. The myc(H-P) region contains a c-myc protein complex binding site. On the other hand, the cells carrying a similar myc-CAT construct, but without the myc(H-P) region, showed very low levels of CAT expression. These cell lines were then synchronized by serum starvation and their CAT expression was examined by Northern blotting. The expression became maximal between G1 and S phases of the cell cycle, in correspondence with the increase of endogenous c-myc expression. CAT expression of the cells containing the CAT gene linked to the SV40 enhancer/ promoter was less affected by cell cycle, neither was the expression of a housekeeping gene, the hypoxanthine phosphoribosyl transferase (HPRT). These results suggest that the myc(H-P) region is important for cell cycle dependent regulation of c-myc expression.

Stimulation of SV40 DNA replication and transcription by Alu family sequence

The sequence motif GGAGGC (Alu core) is present in the Alu family repeats, where it is required for RNA polymerase III promoter function. This motif is also found in the SV40 origin (ori) of replication. Here, an oligonucleotide containing the Alu sequence was inserted into pSV2CAT, a plasmid composed of the SV40 enhancer/promoter/ori linked to the bacterial chloramphenicol acetyltransferase gene (CAT), to see the effect of the Alu sequence on SV40 DNA replication and transcription. Results of transfection experiments in human HeLa cells showed that the Alu sequence stimulated sequence-specifically replication and transcription in the SV40 system. Stimulation effects on DNA replication were observed when the Alu sequence was placed upstream of enhancer/promoter/ori in either orientation, while effects on transcription were detected only when it was inserted in the normal orientation. These effects correlate with sequence-specific binding of two proteins (40 kDa and 120 kDa) to this motif. In fact, binding was abolished by a mutation in the cognate sequence that disrupted stimulation of replication and transcription. Both proteins bind duplex DNA, while the 40 kDa one also binds the minus strand with high affinity.

Mammalian genomic sequences can substitute for the SV40 AT stretch in sustaining replication of the SV40 origin of replication

The core of the SV40 origin of replication (ori) contains a stretch of adenine (A) and thymine (T) residues. This region is very conserved among the papova viruses, and is known to be extremely sensitive to mutations. So far, mutations have been found to drastically reduce, and in most cases abolish, replication. The AT stretch has been shown to be the target for several host cellular proteins that belong to the replication machinery. We reasoned that, in this light, there might exist cellular DNA sequences that can substitute for the SV40 AT stretch. To study this possibility, we digested mammalian genomic DNA and inserted the fragments instead of the SV40 AT stretch in a plasmid carrying the SV40 ori core. The resulting pool was analyzed by a 'replication trap' in CosI cells. We present evidence that there are indeed several mammalian sequences that can substitute for the SV40 AT stretch. All of them are rich in adenines and thymines but, surprisingly, these sequences differ from the wild-type SV40 AT stretch to such extent that at first sight they would seem unlikely to replicate. This is all the more impressive if we consider that another AT-rich sequence from the yeast TRP1 gene, which also carries a similar variation, cannot substitute for the SV40 AT stretch.

Zinc finger mutations that alter domain interactions in the glucocorticoid receptor

The DNA binding domain of steroid receptors coincides with the cysteine-rich region encompassing the two conserved zinc fingers. In the case of the glucocorticoid receptor (GR), a weak transactivation function has been described to be adjacent or partly overlapping to the DNA binding domain, whereas stronger trans-acting functions are encoded by the amino and the carboxy domain. In this report we describe the phenotype produced by stochastic mutations of the zinc finger region. The mutants were obtained either by selected rearrangements of the rat GR cDNA, or by semi-random nucleotide substitutions. All the identified permissive rearrangements were confined to a region downstream from the first zinc finger (duplications starting between residue 474 and 492). In general, the phenotype of point mutations is compatible with established structural data. Nevertheless, we found two unexpected phenotypes. First, we noticed that the double mutant His451 Asn/Ser459Gly is stronger than the wild-type sequence in DNA binding. Secondly, substitution of the conserved Lys461 results in an abnormal behavior of the mutated GR. In particular, the mutant Lys461Tyr (61Y) displays about the same transactivation when tested in form of a minimal GR fragment (amino acids 407/556) as when tested in the amino-prolongued GR fragment (amino acids 3-556, which contains the major transactivation domain of the GR). This is in contrast with the behavior of the other mutants in which the residue 461 is intact. In these cases, transactivation capacity is normally increased more than 30-fold from GR407-556 to GR3-556. These results are discussed in terms of possible cross-talk among the DNA binding domain and other functions residing in the amino domain of the GR.

Stimulation of SV40 DNA replication by the human c-myc enhancer

In earlier studies we had shown that a transcriptional enhancer sequence exists about 2 kb upstream of the human c-myc gene. The core sequence necessary for enhancer activity was defined therein as a 21 bp nucleotide element, which also showed autonomous replicating activity [EMBO J. (1988) 7, 3135-3142; EMBO J. (1989) 8, 4273-4279]. Recently, several reports have substantiated the notion that transcription and replication can be concertedly regulated in a larger number of cases than expected. In this report, we took the simian virus 40 (SV 40) ori/promoter as a model system. The SV40 enhancer is known to enhance transcription from its ori/promoter, but to reduce its replication (probably due to a negative feedback). The SV40 enhancer was replaced by the c-myc enhancer core in order to see its effect upon SV40 DNA replication and transcription. The results showed that besides stimulating transcription, the c-myc enhancer promoted SV40 DNA replication in monkey CosI cells. Stimulation was only observed when the c-myc enhancer was inserted in the 'up-to-down' orientation to the SV40 promoter. The promoting function of the c-myc enhancer on DNA replication correlated with the transcriptional activation function, as determined by systematic point mutations introduced within the 21 bp core sequence.

The AT-rich tract of the SV40 ori core: negative synergism and specific recognition by single stranded and duplex DNA binding proteins

The SV40 origin of replication comprises a run of thymine and adenine residues. Integrity of this AT-rich sequence is known to be essential for replication. We set out to study whether or not these elements can work synergistically to sustain replication. Quite surprisingly, additional copies of the AT stretch linked to a functional SV40 ori core dramatically reduce its replication in Cosl cells, probably by creating some physical block. Interestingly, the same inhibiting effect can be observed with the addition in cis of the yeast ARS consensus, which is homologous to the SV40 AT stretch. This modulation is possibly due to the action of cellular factors that recognize either of the two sequences. In fact, we demonstrate the existence of factor(s) in Cosl crude nuclear extracts that in vitro can specifically bind to either of them. Moreover, we show that these sequence-specific factor(s) (MW about 50 kDa), named SOAP, recognize both single (T-rich strand) and double stranded forms of the AT tracts. Binding to single stranded AT stretches can be specifically inhibited by the corresponding duplex form, but not vice versa.

Activation of c-myc promoter by c-myc protein in serum starved cells

The function of the c-myc protein, the product of a proto oncogene, is not clearly understood although many reports, including ours, suggest that the c-myc protein plays several roles in the regulation of transcription and DNA replication. Here we examined the effects of c-myc protein on transcription from the c-myc promoter, and by inference its role in auto-regulation, after introducing into cultured cells a c-myc expression vector and a CAT reporter gene linked to the promoter and upstream region of the human c-myc gene. To minimize the effects of the endogenous c-myc protein on the exogenously added CAT reporter gene, the transfected cells were treated under serum-free conditions. The results show that CAT expression from the myc promoter increased in a dose-dependent manner after addition of the c-myc expression vector, and that it also required the presence of a c-myc binding sequence previously identified 2 kb upstream from c-myc's first exon. Moreover, the domains of the c-myc protein important for transactivation were determined by use of various deletions mutants of c-myc cDNA. The results showed that the N-terminal portion in the c-myc protein was necessary for transactivation beside the C-terminal portion containing basic region, helix-loop-helix, and leucine zipper.

A novel expression assay to study transcriptional activators

A novel assay to study transcriptional regulation in vivo designated trans-activation-dependent replication (TDR) assay is based on the modulation of a simian virus 40 (SV40)-derived replication system. A mixture of four plasmids (pPARA + pCIS + pTRANS + pREF) is co-transfected into vertebrate cells. After appropriate incubation, the replication of the pPARA plasmid (containing an SV40 origin of replication) is measured with a simple enzymatic test. We demonstrate that the level of replication is dependent on the differential trans-activation of the reporter pCIS (in which SV40 T-antigen is brought under control of the desired promoter) by the specific regulator protein encoded by the pTRANS plasmid. Three advantages make this assay a convenient tool for the systematic analysis of trans-activation in vivo: (1) remarkable sensitivity (higher than conventional assays); (2) rapid sample processing combined with a built-in standard (pREF-plasmid); (3) avoidance of expensive reagents such as freshly radiolabelled probes. We present the application of the TDR assay to the analysis of deletion mutants of the glucocorticoid receptor (GR) and other, GR-based chimeric trans-activators. The results demonstrate that the properties of protein domains are not always additive in a particular chimaera. Further application possibilities of the TDR assay are also discussed.

On the relationship between Machiavellianism and anxiety among Italian undergraduates

139 Italian undergraduates (61 men and 78 women) responded to the Italian version of the Christie's Mach IV scale and to the Italian version of the Spielberger's State-Trait Anxiety Inventory. Positive correlations between Mach IV scores and both State Anxiety and Trait Anxiety scores were found for both sexes. The authors hypothesized that moderate anxiety may be associated with high Machiavellianism. Further implications of the findings were discussed.

[Hydatid cysts of the brain. Diagnostic and therapeutic problems apropos of 100 cases]

The authors report 100 cases of hydatid cysts of the brain operated in the Neurosurgical Department (C.H.U. of Algier). They compars their data with those of the litterature. It appears once more that cerebral hydatidosis affects the children living in endemic countries and looks like a quite pure increased intracranial pressure. Supratentorial situation of the mass can be approached many times by the E.E.G. A right diagnosis is possible in almost all cases (6/7) by angiographic examination. Surgical technique is simple but one must keep a great attention in removing these "virulent" cysts. As a rule, the results are good, as far as the patients are not in a bad status before the operation. Unfortunately becalse of a late diagnosis, one patient among three is blind after the operation as he was before.