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.

Gender and cystectomy for bladder cancer: A high-volume tertiary urologic care center experience.

BACKGROUND: Differences have often been reported in the outcomes of bladder cancer (BC) patients according to gender. OBJECTIVE: This study aims to provide data on patients undergoing radical cystectomy (RC) in a high-volume tertiary urologic center and to assess whether gender discrepancies do exist in terms of surgical options and clinical outcomes. MATERIALS AND METHODS: Consecutive BC patients treated between 2016 and 2020 at a single center (Careggi University Hospital, Florence, Italy) were included in the study. The impact of gender on disease stage at diagnosis, overall survival (OS), and type of surgery was analyzed. RESULTS: The study series comprised 447 patients (85 females and 362 males). At a median follow-up of 28.3 months (IQR: 33.5), OS was 52.6% and cancer-specific survival was 67.6%. Significant differences in OS emerged for age, acute myocardial infarction (AMI), Charlson Comorbidity Index (CCI), pT, and pN. OS rates were higher in patients undergoing robot-assisted surgery and in those receiving open orthotopic neobladder (ONB) (p = 0.0001). No statistically significant differences were found between male and female patients regarding surgical offer in any age group, surgical time, early postoperative complications, pathologic stage, and OS. CONCLUSIONS: After adjustment for pathologic tumor stage and treatment modalities, female and male patients showed similar oncologic outcomes. Further studies should be undertaken to evaluate functional results in women subjected to RC.

Subkilohertz linewidth room-temperature mid-infrared quantum cascade laser using a molecular sub-Doppler reference.

We report on the narrowing of a room-temperature mid-IR quantum cascade laser by frequency locking it to a CO2 sub-Doppler transition obtained by polarization spectroscopy. A locking bandwidth of 250 kHz has been achieved. The laser linewidth is narrowed by more than two orders of magnitude below 1 kHz, and its absolute frequency is stabilized at the same level.

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.

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.

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.

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.

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.

Inverted urothelial papilloma of the upper urinary tract: description of two cases with systematic literature review.

BACKGROUND: Inverted urothelial papilloma (IUP) of the upper urinary tract is an uncommon benign tumour that occasionally presents as a polypoid mass causing urinary obstruction. Histologically, IUP is characterised by a proliferating urothelium arranged in cords and trabeculae, in continuity with overlying intact epithelium, and extending into the lamina propria in a non-invasive, endophytic manner. Cytological atypia is minimal or absent. Top differential diagnoses include urothelial carcinoma with inverted growth pattern and florid ureteritis cystica. Although urothelial carcinomas of the upper urinary tract with prominent inverted growth pattern commonly harbour microsatellite instability, the role of the mutator phenotype pathway in IUP development is still unclear. The aim of this study was to describe two additional cases of IUP of the upper urinary tract, along with an extensive literature review. CASE PRESENTATION: We observed two polypoid tumours originating in the renal pelvis and the distal ureter, respectively. Both patients, a 76-year-old woman and a 56-year-old man, underwent surgery because of the increased likelihood of malignancy. Histology was consistent with IUP and patients are alive and asymptomatic after long-term follow-up (6 years for the renal pelvis lesion and 5 years for the ureter lesion). The tumours retained the expression of the mismatch-repair protein MLH1, MSH2, and PMS2 whereas loss of MSH6 was found in both cases. CONCLUSIONS: When completely resected, IUP does not require rigorous surveillance protocols, such as those for urothelial carcinoma and exophytic urothelial papilloma. It is therefore important for the surgical pathologist to be aware of this rare entity in order to ensure correct patient management.

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.

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.

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.

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.

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.