Prognosis and Outcomes in Early Stage Glottic Carcinoma Involving the Anterior Commissure Treated with Laser CO2 Surgery: A Retrospective Observational Analysis

The anterior commissure (AC) is the area where the vocal cords attach to the thyroid cartilage through Broyles' ligament. Many authors argue that involvement of the anterior commissure in early stage glottic carcinoma (I, II) constitutes a risk factor for local recurrence. The objective of this study is to evaluate whether anterior commissure involvement in early stage glottis cancer is an independent risk factor for recurrence and mortality. The study included all those patients diagnosed with glottis carcinoma in stages I and II of the AJCC treated by transoral laser surgery at the Hospital San Pedro (Logroño, Spain) between 2005 and 2015. Patients were divided into two groups according to the presence (AC1) or absence (AC0) of involvement of the commissure. Of 29 patients treated, 44.8% were AC1. Patients with anterior commissure involvement had more local recurrence (p = 0.2701); higher mortality rate (p = 0.2256); lower disease-free survival (p = 0.0881) and a lower overall survival (p = 0.0331). The 5-year survival rate was 24.5% lower in patients with invasion of the anterior commissure. The involvement of the anterior commissure is an independent risk factor that should be considered in the prognosis of laryngeal cancer.

Mental health and COVID-19 in a general population cohort in Spain (COVICAT study)

PURPOSE

Mental health conditions may affect outcome of COVID-19 disease, while exposure to stressors during the pandemic may impact mental health. The purpose of this study was to examine these factors in relation to ocurrence of depression and anxiety after the first outbreak in Spain.

METHODS

We contacted 9515 participants from a population-based cohort study in Catalonia between May and October 2020. We drew blood samples to establish infection to the virus. Pre-pandemic mental health conditions were confirmed through Electronic Health Registries. We used the Hospital Anxiety and Depression Scale to assess severe depression and anxiety post-pandemic. Exposure to proximal, financial and wider environment stressors during the lockdown were collected. We calculated Relative Risks (RR), adjusting for individual- and contextual covariates.

RESULTS

Pre-pandemic mental health disorders were not associated with SARS-CoV-2 infection , but were associated with severity of COVID-19 disease. People with pre-existing mental health disorders showed higher prevalence of severe depression (25.4%) and anxiety (37.8%) than those without prior mental disorders (4.9% and 10.1%). Living alone was a strong predictor of severe depression among mental health patients (RR = 1.6, 95% CI 1.2-2.2). Among those without prior mental health disorders, post-lockdown depression and anxiety were associated with household interpersonal conflicts (RR = 2.6, 95% CI 2.1-3.1; RR = 2.1, 95% CI 1.9-2.4) and financial instability (RR = 2.2, 95% CI 1.8-2.9; 1.9, 95% CI 1.6-2.2).

CONCLUSIONS

The COVID-19 pandemic and the lockdown were associated with increased post-lockdown depression and anxiety. Patients with pre-existing mental health conditions are a vulnerable group for severe COVID-19 disease.

Identification of Tyrosine and Nitrotyrosine with a Mixed-Mode Solid-Phase Extraction Cleanup Followed by Liquid Chromatography-Electrospray Time-of-Flight Mass Spectrometry in Plants

In higher plants, there is a growing interest in the study of protein tyrosine nitration (NO₂Tyr) as well as the identification of in vivo nitrated proteins. Different methods have been developed for identifying nitrotyrosine in biological samples. However, these analyses are difficult because tyrosine nitration is a very low-abundance posttranslational protein modification (PTM) and the lack of efficient enrichment methods for detection. The identification and quantification of NO₂Tyr in proteins has represented a challenge for researchers.In this chapter a new method for determining NO₂Tyr and tyrosine (Tyr) in Arabidopsis thaliana cell-suspension culture extracts is proposed. The quantification was performed using a simple, sensitive, and specific sample preparation assay based on mixed-mode solid-phase extraction (SPE) which was developed for the quantification of trace NO₂Tyr in Arabidopsis extracts by liquid chromatography-electrospray time-of-flight mass spectrometry (LC-TOFMS).

A dual system formed by the ARC and NR molybdoenzymes mediates nitrite-dependent NO production in Chlamydomonas

Nitric oxide (NO) is a relevant signal molecule involved in many plant processes. However, the mechanisms and proteins responsible for its synthesis are scarcely known. In most photosynthetic organisms NO synthases have not been identified, and Nitrate Reductase (NR) has been proposed as the main enzymatic NO source, a process that in vitro is also catalysed by other molybdoenzymes. By studying transcriptional regulation, enzyme approaches, activity assays with in vitro purified proteins and in vivo and in vitro NO determinations, we have addressed the role of NR and Amidoxime Reducing Component (ARC) in the NO synthesis process. N\R and ARC were intimately related both at transcriptional and activity level. Thus, arc mutants showed high NIA1 (NR gene) expression and NR activity. Conversely, mutants without active NR displayed an increased ARC expression in nitrite medium. Our results with nia1 and arc mutants and with purified enzymes support that ARC catalyses the NO production from nitrite taking electrons from NR and not from Cytb5-1/Cytb5-Reductase, the component partners previously described for ARC (proposed as NOFNiR, Nitric Oxide-Forming Nitrite Reductase). This NR-ARC dual system would be able to produce NO in the presence of nitrate, condition under which NR is unable to do it.

Quantification and Localization of S-Nitrosothiols (SNOs) in Higher Plants

S-nitrosothiols (SNOs) are a family of molecules produced by the reaction of nitric oxide (NO) with -SH thiol groups present in the cysteine residues of proteins and peptides caused by a posttranslational modification (PTM) known as S-nitrosylation (strictly speaking S-nitrosation) that can affect the cellular function of proteins. These molecules are a relatively more stable form of NO and consequently can act as a major intracellular NO reservoir and, in some cases, as a long-distance NO signal. Additionally, SNOs can be transferred between small peptides and protein thiol groups through S-transnitrosylation mechanisms. Thus, detection and cellular localization of SNOs in plant cells can be useful tools to determine how these molecules are modulated under physiological and adverse conditions and to determine their importance as a mechanism for regulating different biochemical pathways. Using a highly sensitive chemiluminescence ozone technique and a specific fluorescence probe (Alexa Fluor 488 Hg-link phenylmercury), the methods described in this chapter enable us to determine SNOs in an nM range as well as their cellular distribution in the tissues of different plant species.

Dual regulation of cytosolic ascorbate peroxidase (APX) by tyrosine nitration and S-nitrosylation

Post-translational modifications (PTMs) mediated by nitric oxide (NO)-derived molecules have become a new area of research, as they can modulate the function of target proteins. Proteomic data have shown that ascorbate peroxidase (APX) is one of the potential targets of PTMs mediated by NO-derived molecules. Using recombinant pea cytosolic APX, the impact of peroxynitrite (ONOO-) and S-nitrosoglutathione (GSNO), which are known to mediate protein nitration and S-nitrosylation processes, respectively, was analysed. While peroxynitrite inhibits APX activity, GSNO enhances its enzymatic activity. Mass spectrometric analysis of the nitrated APX enabled the determination that Tyr5 and Tyr235 were exclusively nitrated to 3-nitrotyrosine by peroxynitrite. Residue Cys32 was identified by the biotin switch method as S-nitrosylated. The location of these residues on the structure of pea APX reveals that Tyr235 is found at the bottom of the pocket where the haem group is enclosed, whereas Cys32 is at the ascorbate binding site. Pea plants grown under saline (150 mM NaCl) stress showed an enhancement of both APX activity and S-nitrosylated APX, as well as an increase of H2O2, NO, and S-nitrosothiol (SNO) content that can justify the induction of the APX activity. The results provide new insight into the molecular mechanism of the regulation of APX which can be both inactivated by irreversible nitration and activated by reversible S-nitrosylation.

Sleep fragmentation promotes NADPH oxidase 2-mediated adipose tissue inflammation leading to insulin resistance in mice

Background

Short sleep has been implicated in higher risk of obesity in humans, and is associated with insulin resistance. However, the effects of fragmented sleep (SF) rather than curtailed sleep on glucose homeostasis are unknown.

Methods

Wild type and NADPH oxidase 2 (Nox2) null male mice were subjected to SF or sleep control (SC) conditions for 3 days-3 weeks. Systemic and visceral adipose tissue (VAT) insulin sensitivity tests, glucose tolerance test, FACS and immunohistochemistry for macrophages and sub-types (M1 and M2) and Nox expression and activity were examined.

Results

Here show that SF in the absence of sleep curtailment induces time-dependent insulin resistance, in vivo and also in vitro in VAT. Oxidative stress pathways were up-regulated by SF in VAT, and were accompanied by M1 macrophage polarization. SF-induced oxidative stress, inflammation, and insulin resistance in VAT were completely abrogated in genetically altered mice lacking Nox2 activity.

Conclusions

These studies imply that SF, a frequent occurrence in many disorders and more specifically in sleep apnea, is a potent inducer of insulin resistance via activation of oxidative stress and inflammatory pathways, thereby opening the way for therapeutic strategies.

Vinyl sulfone silica: application of an open preactivated support to the study of transnitrosylation of plant proteins by S-nitrosoglutathione

BACKGROUND

S-nitrosylaton is implicated in the regulation of numerous signaling pathways with a diversity of regulatory roles. The high lability of the S-NO bond makes the study of proteins regulated by S-nitrosylation/denitrosylation a challenging task and most studies have focused on already S-nitrosylated proteins. We hypothesize that: i) S-nitrosoglutathione (GSNO) transnitrosylation is a feasible mechanism to account for the physiological S-nitrosylation of rather electropositive sulfur atoms from proteins, ii) affinity chromatography is a suitable approach to isolate proteins that are prone to undergo S-transnitrosylation and iii) vinyl sulfone silica is a suitable chromatographic bead.

RESULTS

The combination of vinyl sulfone silica with GSNO yielded an affinity resin that withstood high ionic strength without shrinking or deforming and that it was suitable to isolate potential GSNO transnitrosylation target candidates. Fractions eluted at 1500 mM NaCl resulted in a symmetrical peak for both, protein and S-nitrosothiols, supporting the idea of transnitrosylation by GSNO as a selective process that involves strong and specific interactions with the target protein. Proteomic analysis led to the identification of 22 physiological significant enzymes that differ with the tissue analyzed, being regulatory proteins the most abundant group in hypocotyls. The identification of chloroplastidic FBPase, proteasome, GTP-binding protein, heat shock Hsp70, syntaxin, catalase I, thioredoxin peroxidase and cytochrome P450 that have already been reported as S-nitrosylated by other techniques can be considered as internal positive controls that validate our experimental approach. An additional validation was provided by the prediction of the S-nitrosylation sites in 19 of the GSNO transnitrosylation target candidates.

CONCLUSIONS

Vinyl sulfone silica is an open immobilization support that can be turned ad hoc and in a straightforward manner into an affinity resin. Its potential in omic sciences was successfully put to test in the context of the analysis of post-translational modification by S-nitrosylation with two different tissues: mature pea leaves and embryogenic sunflower hypocotyls. The identified proteins reveal an intriguing overlap among S-nitrosylation and both tyrosine nitration and thioredoxin regulation. Chloroplastidic FBPase is a paradigm of such overlap of post-translational modifications since it is reversible modified by thioredoxin and S-nitrosylation and irreversibly by tyrosine nitration. Our results suggest a complex interrelation among different modulation mechanisms mediated by NO-derived molecules.

High temperature triggers the metabolism of S-nitrosothiols in sunflower mediating a process of nitrosative stress which provokes the inhibition of ferredoxin-NADP reductase by tyrosine nitration

High temperature (HT) is considered a major abiotic stress that negatively affects both vegetative and reproductive growth. Whereas the metabolism of reactive oxygen species (ROS) is well established under HT, less is known about the metabolism of reactive nitrogen species (RNS). In sunflower (Helianthus annuus L.) seedlings exposed to HT, NO content as well as S-nitrosoglutathione reductase (GSNOR) activity and expression were down-regulated with the simultaneous accumulation of total S-nitrosothiols (SNOs) including S-nitrosoglutathione (GSNO). However, the content of tyrosine nitration (NO(2) -Tyr) studied by high-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) and by confocal laser scanning microscope was induced. Nitroproteome analysis under HT showed that this stress induced the protein expression of 13 tyrosine-nitrated proteins. Among the induced proteins, ferredoxin-NADP reductase (FNR) was selected to evaluate the effect of nitration on its activity after heat stress and in vitro conditions using 3-morpholinosydnonimine (SIN-1) (peroxynitrite donor) as the nitrating agent, the FNR activity being inhibited. Taken together, these results suggest that HT augments SNOs, which appear to mediate protein tyrosine nitration, inhibiting FNR, which is involved in the photosynthesis process.

Functional analysis of superoxide dismutases (SODs) in sunflower under biotic and abiotic stress conditions. Identification of two new genes of mitochondrial Mn-SOD

Superoxide dismutases (SODs) are a family of metalloenzymes that catalyse the disproportionation of superoxide radicals into hydrogen peroxide and oxygen. In sunflower (Helianthus annuus L.) seedlings, two new Mn-SOD isozymes, designated as I and II, were identified. However, no evidence for a Fe-SOD was found. Both Mn-SOD I and Mn-SOD II have a cleaved sequence of 14 residues that target the mitochondrion with a probability of 81% and 95%, respectively. The gene expression of these new mitochondrial Mn-SODs as well as the previously reported cytosolic and chloroplastic CuZnSODs was analyzed by real-time quantitative reverse transcription-PCR. This was done in the main organs (roots, hypocotyls, and cotyledons) of sunflower seedlings and also under biotic (infection by the pathogen Plasmopara halstedii) and abiotic stress conditions, including high and low temperature and mechanical wounding. Both CuZn-SODs had a gene expression of 1000-fold higher than that of mitochondrial Mn-SODs. And the expression of the Mn-SOD I was approximately 12-fold higher than that of Mn-SOD II. The Mn-SOD I showed a significant modulation in response to the assayed biotic and abiotic stresses even when it had no apparent oxidative stress, such as low temperature. Thus, it is proposed that the mitochondrial Mn-SOD I gene could act as an early sensor of adverse conditions to prevent potential oxidative damage.

Mechanical wounding induces a nitrosative stress by down-regulation of GSNO reductase and an increase in S-nitrosothiols in sunflower (Helianthus annuus) seedlings

Nitric oxide (NO) and related molecules such as peroxynitrite, S-nitrosoglutathione (GSNO), and nitrotyrosine, among others, are involved in physiological processes as well in the mechanisms of response to stress conditions. In sunflower seedlings exposed to five different adverse environmental conditions (low temperature, mechanical wounding, high light intensity, continuous light, and continuous darkness), key components of the metabolism of reactive nitrogen species (RNS) and reactive oxygen species (ROS), including the enzyme activities L-arginine-dependent nitric oxide synthase (NOS), S-nitrosogluthathione reductase (GSNOR), nitrate reductase (NR), catalase, and superoxide dismutase, the content of lipid hydroperoxide, hydrogen peroxide, S-nitrosothiols (SNOs), the cellular level of NO, GSNO, and GSNOR, and protein tyrosine nitration [nitrotyrosine (NO(2)-Tyr)] were analysed. Among the stress conditions studied, mechanical wounding was the only one that caused a down-regulation of NOS and GSNOR activities, which in turn provoked an accumulation of SNOs. The analyses of the cellular content of NO, GSNO, GSNOR, and NO(2)-Tyr by confocal laser scanning microscopy confirmed these biochemical data. Therefore, it is proposed that mechanical wounding triggers the accumulation of SNOs, specifically GSNO, due to a down-regulation of GSNOR activity, while NO(2)-Tyr increases. Consequently a process of nitrosative stress is induced in sunflower seedlings and SNOs constitute a new wound signal in plants.

Protein targets of tyrosine nitration in sunflower (Helianthus annuus L.) hypocotyls

Tyrosine nitration is recognized as an important post-translational protein modification in animal cells that can be used as an indicator of a nitrosative process. However, in plant systems, there is scant information on proteins that undergo this process. In sunflower hypocotyls, the content of tyrosine nitration (NO(2)-Tyr) and the identification of nitrated proteins were studied by high-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) and proteomic approaches, respectively. In addition, the cell localization of nitrotyrosine proteins and peroxynitrite were analysed by confocal laser-scanning microscopy (CLSM) using antibodies against 3-nitrotyrosine and 3'-(p-aminophenyl) fluorescein (APF) as the fluorescent probe, in that order. The concentration of Tyr and NO(2)-Tyr in hypocotyls was 0.56 micromol mg(-1) protein and 0.19 pmol mg(-1) protein, respectively. By proteomic analysis, a total of 21 nitrotyrosine-immunopositive proteins were identified. These targets include proteins involved in photosynthesis, and in antioxidant, ATP, carbohydrate, and nitrogen metabolism. Among the proteins identified, S-adenosyl homocysteine hydrolase (SAHH) was selected as a model to evaluate the effect of nitration on SAHH activity using SIN-1 (a peroxynitrite donor) as the nitrating agent. When the hypocotyl extracts were exposed to 0.5 mM, 1 mM, and 5 mM SIN-1, the SAHH activity was inhibited by some 49%, 89%, and 94%, respectively. In silico analysis of the barley SAHH sequence, characterized Tyr448 as the most likely potential target for nitration. In summary, the present data are the first in plants concerning the content of nitrotyrosine and the identification of candidates of protein nitration. Taken together, the results suggest that Tyr nitration occurs in plant tissues under physiological conditions that could constitute an important process of protein regulation in such a way that, when it is overproduced in adverse circumstances, it can be used as a marker of nitrosative stress.

Metabolism of reactive nitrogen species in pea plants under abiotic stress conditions

Nitric oxide (*NO) is a key signaling molecule in different physiological processes of animals and plants. However, little is known about the metabolism of endogenous *NO and other reactive nitrogen species (RNS) in plants under abiotic stress conditions. Using pea plants exposed to six different abiotic stress conditions (high light intensity, low and high temperature, continuous light, continuous dark and mechanical wounding), several key components of the metabolism of RNS including the content of *NO, S-nitrosothiols (RSNOs) and nitrite plus nitrate, the enzyme activities of l-arginine-dependent nitric oxide synthase (NOS) and S-nitrosogluthathione reductase (GSNOR), and the profile of protein tyrosine nitration (NO(2)-Tyr) were analyzed in leaves. Low temperature was the stress that produced the highest increase of NOS and GSNOR activities, and this was accompanied by an increase in the content of total *NO and S-nitrosothiols, and an intensification of the immunoreactivity with an antibody against NO(2)-Tyr. Mechanical wounding, high temperature and light also had a clear activating effect on the different indicators of RNS metabolism in pea plants. However, the total content of nitrite and nitrate in leaves was not affected by any of these stresses. Considering that protein tyrosine nitration is a potential marker of nitrosative stress, the results obtained suggest that low and high temperature, continuous light and high light intensity are abiotic stress conditions that can induce nitrosative stress in pea plants.

Upper airway collapse and reopening induce inflammation in a sleep apnoea model

The upper airway of obstructive sleep apnoea patients is subjected to recurrent negative pressure swings promoting its collapse and reopening. The aim of the present study was to ascertain whether this mechanical stress induces upper airway inflammation in a rat model. The upper airway of Sprague-Dawley rats was subjected to a periodic pattern of recurrent negative (-40 cmH2O, 1 s) and positive (4 cmH2O, 2 s) pressures inducing collapse and reopening for 5 h. Rats that were instrumented but not subjected to negative pressure swings were used as controls. The gene expression of the pro-inflammatory biomarkers macrophage inflammatory protein (MIP)-2, tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and P-selectin in the soft palate and larynx tissues was assessed by real-time PCR. A marked overexpression of MIP-2, TNF-alpha, IL-1beta and P-selectin (approximately 40-, 24-, 47- and 7-fold greater than controls, respectively) was observed in the larynx tissue; similar results were found in the soft palate tissue (approximately 14-, 7-, 35- and 11-fold greater than controls, respectively). Recurrent upper airway collapse and reopening mimicking those experienced by obstructive sleep apnoea patients triggered an early local inflammatory process. These results could explain the inflammation observed in the upper airway of obstructive sleep apnoea patients.

Nitrosative stress in plants

Nitrosative stress has become a usual term in the physiology of nitric oxide in mammalian systems. However, in plants there is much less information on this type of stress. Using olive leaves as experimental model, the effect of salinity on the potential induction of nitrosative stress was studied. The enzymatic l-arginine-dependent production of nitric oxide (NOS activity) was measured by ozone chemiluminiscence. The specific activity of NOS in olive leaves was 0.280nmol NOmg(-1) proteinmin(-1), and was dependent on l-arginine, NADPH and calcium. Salt stress (200mM NaCl) caused an increase of the l-arginine-dependent production of nitric oxide (NO), total S-nitrosothiols (RSNO) and number of proteins that underwent tyrosine nitration. Confocal laser scanning microscopy analysis using either specific fluorescent probes for NO and RSNO or antibodies to S-nitrosoglutathione and 3-nitrotyrosine, showed also a general increase of these reactive nitrogen species (RNS) mainly in the vascular tissue. Taken together, these findings show that in olive leaves salinity induces nitrosative stress, and vascular tissues could play an important role in the redistribution of NO-derived molecules during nitrosative stress.

Constitutive arginine-dependent nitric oxide synthase activity in different organs of pea seedlings during plant development

Nitric oxide (NO) is an important signalling molecule in different animal and plant physiological processes. Little is known about its biological function in plants and on the enzymatic source or site of NO production during plant development. The endogenous NO production from L-arginine (NO synthase activity) was analyzed in leaves, stems and roots during plant development, using pea seedlings as a model. NOS activity was analyzed using a novel chemiluminescence-based assay which is more sensitive and specific than previous methods used in plant tissues. In parallel, NO accumulation was analyzed by confocal laser scanning microscopy using as fluorescent probes either DAF-2 DA or DAF-FM DA. A strong increase in NOS activity was detected in stems after 11 days growth, coinciding with the maximum stem elongation. The arginine-dependent NOS activity was constitutive and sensitive to aminoguanidine, a well-known irreversible inhibitor of animal NOS, and this NOS activity was differentially modulated depending on the plant organ and seedling developmental stage. In all tissues studied, NO was localized mainly in the vascular tissue (xylem) and epidermal cells and in root hairs. These loci of NO generation and accumulation suggest novel functions for NO in these cell types.

The expression of different superoxide dismutase forms is cell-type dependent in olive (Olea europaea L.) leaves

Superoxide dismutase (SOD) is a key antioxidant enzyme present in prokaryotic and eukaryotic cells as a first line of defense against the accumulation of superoxide radicals. In olive leaves, the SOD enzymatic system was characterized and was found to be comprised of three isozymes, an Mn-SOD, an Fe-SOD and a CuZn-SOD. Transcript expression analysis of whole leaves showed that the three isozymes represented 82, 17 and 0.8% of the total SOD expressed, respectively. Using the combination of laser capture microdissection (LCM) and real-time quantitative reverse transcription-PCR (RT-PCR), the expression of these SOD isozymes was studied in different cell types of olive leaves, including spongy mesophyll, palisade mesophyll, xylem and phloem. In spongy mesophyll cells, the isozyme proportion was similar to that in whole leaves, but in the other cells the proportion of expressed SOD isozymes was different. In palisade mesophyll cells, Fe-SOD was the most abundant, followed by Mn-SOD and CuZn-SOD, but in phloem cells Mn-SOD was the most prominent isozyme, and Fe-SOD was present in trace amounts. In xylem cells, only the Mn-SOD was detected. On the other hand, the highest accumulation of superoxide radicals was localized in vascular tissue which was the tissue with the lowest level of SOD transcripts. These data show that in olive leaves, each SOD isozyme has a different gene expression depending on the cell type of the leaf.

The dehydrogenase-mediated recycling of NADPH is a key antioxidant system against salt-induced oxidative stress in olive plants

NADPH is an important molecule in the redox balance of the cell. In this paper, using olive tissue cultures as a model of the function of the NADPH-generating dehydrogenases in the mechanism of oxidative stress induced by severe salinity conditions was studied. When olive (Olea europaea) plants were grown with 200 mM NaCl, a 40% reduction in leaf fresh weight was produced. The content of non-enzymatic antioxidants such as ascorbate and glutathione was diminished between 20% to 39%, whereas the H2O2 content was increased threefold. In contrast, the analysis of the activity and protein contents of the main antioxidative enzymes showed a significant increase of catalase, superoxide dismutase and glutathione reductase. Overall, these changes strongly suggests that NaCl induces oxidative stress in olive plants. On the other hand, while the content of glucose-6-phosphate was increased almost eightfold in leaves of plants grown under salt stress, the content of NAD(P)H (reduced and oxided forms) did not show significant variations. Under salt stress conditions, the activity and protein contents of the main NADPH-recycling enzymes, glucose-6-phosphate dehydrogenase (G6PDH), isocitrate dehydrogenase (ICDH), malic enzyme (ME) and ferrodoxin-NADP reductase (FNR) showed an enhancement of 30-50%. In leaves of olive plants grown with 200 mM NaCl, analysis of G6PDH by immunocytochemistry and confocal laser scanning microscopy showed a general increase of this protein in epidermis, palisade and spongy mesophyll cells. These results indicate that in olive plants, salinity causes reactive oxygen species (ROS)-mediated oxidative stress, and plants respond to this situation by inducing different antioxidative enzymes, especially the NADPH-producing dehydrogenases in order to recycle NADPH necessary for the protection against oxidative damages. These NADP-dehydrogenases appear to be key antioxidative enzymes in olive plants under salt stress conditions.

Localization of S-nitrosoglutathione and expression of S-nitrosoglutathione reductase in pea plants under cadmium stress

S-nitrosoglutathione (GSNO) is considered a natural nitric oxide (NO.) reservoir and a reactive nitrogen intermediate in animal cells, but little is known about this molecule and its metabolism in plant systems. In this work, using pea plants as a model system, the presence of GSNO in collenchyma cells was demonstrated by an immunohistochemical method. When pea plants were grown with a toxic Cd concentration (50 microM) the content of GSNO in collenchyma cells was drastically reduced. Determination of the nitric oxide (NO.) and gluthathione contents in leaves by confocal laser scanning microscopy and HPLC, respectively, showed a marked decrease of both compounds in plants treated with cadmium. The analysis of the S-nitrosoglutathione reductase (GSNOR) activity and its transcript expression in leaves showed a reduction of 31% by cadmium. These results indicate that GSNO is associated with a specific plant cell type, and this metabolite and its related catabolic activity, GSNOR, are both down-regulated under Cd stress.

Cellular and subcellular localization of endogenous nitric oxide in young and senescent pea plants

The cellular and subcellular localization of endogenous nitric oxide (NO.) in leaves from young and senescent pea (Pisum sativum) plants was studied. Confocal laser scanning microscopy analysis of pea leaf sections with the fluorescent probe 4,5-diaminofluorescein diacetate revealed that endogenous NO. was mainly present in vascular tissues (xylem and phloem). Green fluorescence spots were also detected in the epidermal cells, palisade and spongy mesophyll cells, and guard cells. In senescent leaves, NO. generation was clearly reduced in the vascular tissues. At the subcellular level, by electron paramagnetic resonance spectroscopy with the spin trap Fe(MGD)(2) and fluorometric analysis with 4,5-diaminofluorescein diacetate, NO. was found to be an endogenous metabolite of peroxisomes. The characteristic three-line electron paramagnetic resonance spectrum of NO., with g = 2.05 and a(N) = 12.8 G, was detected in peroxisomes. By fluorometry, NO. was also found in these organelles, and the level measured of NO. was linearly dependent on the amount of peroxisomal protein. The enzymatic production of NO. from l-Arg (nitric oxide synthase [NOS]-like activity) was measured by ozone chemiluminiscence. The specific activity of peroxisomal NOS was 4.9 nmol NO. mg(-1) protein min(-1); was strictly dependent on NADPH, calmodulin, and BH(4); and required calcium. In senescent pea leaves, the NOS-like activity of peroxisomes was down-regulated by 72%. It is proposed that peroxisomal NO. could be involved in the process of senescence of pea leaves.

Undetected invasive lobular carcinoma of the breast: review of false-negative smears

Analysis of a series of 34 fine-needle aspirations (FNA) from 28 patients with invasive lobular carcinoma (ILC) was undertaken. The false-negative smears were reviewed to reveal the cause of such a relatively frequent error. This was a retrospective study and comparison between the cytological and pathological findings in a series of 34 FNA. Three cases were excluded without sufficient material. Twelve cases were positive, nine suspicious of malignancy, and 10 were considered false-negatives. In a second analysis of this later group, one was reclassified as carcinoma, two reconsidered without sufficient material for diagnosis, and the remaining seven, still considered negatives, constituted the core of this study. Of these seven, there were none with hypercellular smears and in six there was a predominance of fat-tissue fragments. The scarce epithelial component showed honeycomb-flat sheets in four, loose clusters in three, small and tight clusters with irregular limits in six, and more than 10% of isolated epithelial cells (noncohesive cells) in one case. "Staghorns" were undetected and myoepithelial cell nuclei were very scarce in all cases. Some nuclear enlargement was detected in one, angulated nuclear contour in three, and nuclear crowding was present in five. All seven had fine, homogeneous chromatin, without prominent nucleoli. Cytoplasmic limits were undefined in all but one (6/7) and occasional cytoplasmic vacuolization was detected in two. Hypocellular smears with few, small, and dense groups (but always with more than 10 groups in at least one smear) can be related with ILC. In these cases, further studies are recommended to exclude malignancy. The loose cluster and flat sheets identified in four cases represent a benign epithelial hyperplasia mixed with the ILC.

Molecular and kinetic characterization and cell type location of inducible nitric oxide synthase in fish

We have found conclusive evidence for inducible nitric oxide synthase (iNOS) activity in rainbow trout (Oncorhynchus mykiss) tissue by means of biochemical, immunohistochemical, and immunoblotting analyses. This Ca(2+)-independent enzyme uses L-arginine to produce nitric oxide and L-citrulline. It was significantly inhibited by the L-arginine analogs N(omega)-monomethyl-L-arginine and N(G)-nitro-L-arginine methyl ester. Kinetic analyses showed typical Michaelian behavior with no evidence of cooperative effects. The specific activities of the liver and head kidney enzymes were 27 and 106 pmoles. min(-1). mg protein(-1), respectively, with similar values for K(m) (11 microM), all of which correspond well with the values for other previously characterized iNOS. Western blot analyses revealed a single band of M(R) = 130 kDa tested with an iNOS antiserum. At the ultrastructural level, cells with NADPH-diaphorase activity and iNOS immunoreactivity were identified as being heterophilic granulocytes in head kidney tissue and neutrophils and macrophages in hepatic tissue. The presence of an iNOS isoform in these fish tissues implies that these cells are capable of generating nitric oxide, thus pointing to the potential role of this enzyme in fish defense mechanisms.

Localization of nitric-oxide synthase in plant peroxisomes

The presence of nitric-oxide synthase (NOS) in peroxisomes from leaves of pea plants (Pisum sativum L.) was studied. Plant organelles were purified by differential and sucrose density gradient centrifugation. In purified intact peroxisomes a Ca(2+)-dependent NOS activity of 5.61 nmol of L-[(3)H]citrulline mg(-1) protein min(-1) was measured while no activity was detected in mitochondria. The peroxisomal NOS activity was clearly inhibited (60-90%) by different well characterized inhibitors of mammalian NO synthases. The immunoblot analysis of peroxisomes with a polyclonal antibody against the C terminus region of murine iNOS revealed an immunoreactive protein of 130 kDa. Electron microscopy immunogold-labeling confirmed the subcellular localization of NOS in the matrix of peroxisomes as well as in chloroplasts. The presence of NOS in peroxisomes suggests that these oxidative organelles are a cellular source of nitric oxide (NO) and implies new roles for peroxisomes in the cellular signal transduction mechanisms.

Localization of nitric-oxide synthase in plant peroxisomes

The presence of nitric-oxide synthase (NOS) in peroxisomes from leaves of pea plants (Pisum sativum L.) was studied. Plant organelles were purified by differential and sucrose density gradient centrifugation. In purified intact peroxisomes a Ca(2+)-dependent NOS activity of 5.61 nmol of L-[(3)H]citrulline mg(-1) protein min(-1) was measured while no activity was detected in mitochondria. The peroxisomal NOS activity was clearly inhibited (60-90%) by different well characterized inhibitors of mammalian NO synthases. The immunoblot analysis of peroxisomes with a polyclonal antibody against the C terminus region of murine iNOS revealed an immunoreactive protein of 130 kDa. Electron microscopy immunogold-labeling confirmed the subcellular localization of NOS in the matrix of peroxisomes as well as in chloroplasts. The presence of NOS in peroxisomes suggests that these oxidative organelles are a cellular source of nitric oxide (NO) and implies new roles for peroxisomes in the cellular signal transduction mechanisms.

Rescreening of atypical cervicovaginal smears using PAPNET

BACKGROUND

Atypical squamous cells of undetermined significance (ASCUS) is a cytopathologic term used to describe cases without specific pathologic substratum. Between 10-60% of ASCUS cases correspond to squamous intraepithelial lesions (SIL).

METHODS

The objectives of this study were: 1) to detect the pathologic significance of ASCUS in study patients, 2) to determine whether PAPNET identifies these cases, and 3) to compare the results of PAPNET with those of a second conventional screening. One hundred and sixty-three consecutive patients with the cytologic diagnosis of ASCUS and adequate follow-up were selected. Of these, 111 patients had colposcopic lesions and biopsies were performed; in the remaining 52 cases colposcopy was negative, as were 3 consecutive annual Papanicolaou smears. In a blind review, all 163 cases were rescreened using PAPNET. A second manual screening was performed for comparison.

RESULTS

One hundred and twenty-six of the 163 cases (77.3%) showed no SIL on biopsy or follow-up. Of the 37 pathologic cases, the diagnosis was koilocytosis (flat condyloma) in 13 cases (8%), cervical intraepithelial neoplasia (CIN) type I in 11 cases (6.8%) low grade SIL [LSIL] in a total of 24 cases [14.8%]), and CIN II-III or high grade SIL (HSIL) in 11 cases (6.8%). In the review using PAPNET, 57 previous ASCUS cases were classified correctly as negative, and 7 of 13 koilocytosis cases (54%), 9 of 11 CIN I cases (82%), and 7 of 11 CIN II-III cases (64%) were diagnosed correctly. In the second conventional screening, 74 cases were negative and 77 cases were ASCUS; only 3 of 13 koilocytosis cases (23%), 4 of 11 CIN I cases (36.4%) and 5 of 11 CIN II-III cases (45.5%) were reclassified correctly.

CONCLUSIONS

Among 163 patients with ASCUS, 77.3% had no precancerous squamous lesions. Concordance with definitive diagnosis was more accurate in our study using PAPNET analysis (Kappa index [K] = 0.7158) than by second conventional screening (K = 0.4537). Furthermore, we reclassified 35% of smears as negative and 15% as SIL.

Single cell analysis of tyrosine kinase dependent and independent Ca2+ fluxes in progesterone induced acrosome reaction

In this study we developed a single cell analysis protocol with which protein tyrosine kinase (PTK)-dependent and independent Ca2+ fluxes occurring in human spermatozoa in response to progesterone were evaluated. By recording the fluorescence emitted by fluo-3-loaded spermatozoa using a confocal laser scanning microscopy system it was possible not only to monitor relative changes in the intracellular free Ca2+ concentration ([Ca2+]i) but also to determine the time at which the acrosomal exocytosis began. The addition of progesterone produced a rapid transient [Ca2+]i increase in 35% of spermatozoa. In approximately 10% of spermatozoa, this initial [Ca2+]i increase was followed by a secondary [Ca2+]i increase beginning 2-10 min after the progesterone addition and leading to the acrosomal exocytosis in most of these spermatozoa. On the other hand, a rapid triggering of exocytosis during the initial [Ca2+]i increase was a relatively infrequent observation. The inhibition of PTK with genistein or herbimycin A did not influence the initial progesterone-induced [Ca2+]i increase but inhibited the secondary [Ca2+]i increase and the ensuing acrosomal exocytosis. The initial PTK-independent Ca2+ response could be induced by progesterone in both non-capacitated and capacitated spermatozoa, whereas the ability to generate the secondary, PTK-dependent response developed during in-vitro capacitation.

Superoxide dismutase in human sperm suspensions: relationship with cellular composition, oxidative stress, and sperm function

Sensitive techniques have been developed for monitoring superoxide dismutase (SOD) activities in human sperm preparations. In contradiction to the protective role normally assigned to SOD, populations of defective spermatozoa recovered from the low density region of Percoll gradients were found to have three times more SOD than functionally competent preparations pelleting in high density Percoll. SOD activity was negatively correlated with the movement characteristics of human spermatozoa and their capacity for oocyte fusion, and positively associated with the induction of peroxidative damage. SOD activity was also highly correlated with other markers of the cytoplasmic space, creatine kinase (CK), and glucose-6-phosphate dehydrogenase (G-6-PDH). We conclude that while SOD may play a physiological role in maintaining a balance between O2.- and H2O2, high levels of this enzyme are associated with impaired sperm function because (a) the human spermatozoon is highly susceptible to the cytotoxic effects of H2O2, (b) O2.- is an important mediator of normal sperm function, and (c) high SOD activities reflect errors in spermatogenesis associated with germ cell exfoliation and the retention of excess residual cytoplasm by the spermatozoa.

Maximum respiratory pressures in trumpet players

We studied whether experienced trumpet players can develop higher pressures with their inspiratory and expiratory muscles than untrained subjects. Twelve male trumpet players (mean age, 22.4 +/- 3.3 years) participated in the study. All of them had played the trumpet for at least 4 years and were nonsmokers. Twelve healthy male subjects (mean age, 23.3 +/- 3.1 years) participated as a control group. There were no differences in spirometric parameters between both groups. Maximum respiratory pressures were higher in the trumpet player group (trumpet players: Pmax 151.3 +/- 19.8 cm H2O; Pemax, 234.6 +/- 53.9 cm H2O; control group: Pemax, 106.7 +/- 10.4 cm H2O; Pemax, 189.6 +/- 14.6 cm H2O). We concluded that in young trumpet players, maximum respiratory pressures are higher than in young people who do not play wind instruments. This is most probably a consequence of respiratory muscle training with a wind instrument.

Differential sensitivity of progesterone- and zona pellucida-induced acrosome reactions to pertussis toxin

Pertussis toxin-sensitive guanine nucleotide-binding regulatory proteins (G proteins) have previously been shown to mediate the zone pellucida-induced acrosome reaction in mammalian sperm. In this study we compared the inhibitory effect of pertussis toxin on the zona-induced acrosome reaction in human spermatozoa with that on the reaction induced by progesterone, another physiological acrosome reaction-promoting stimulus associated with the ovulated oocyte. Up to the concentration of 1 microgram/ml, pertussis toxin did not produce any direct effects on the acrosome reaction frequency nor did it influence sperm movement and viability. However, preincubation of spermatozoa with the toxin at a concentration of 100 ng/ml completely abolished the increase in the acrosome reaction frequency upon subsequent exposure to solubilized zona pellucida material. In contrast, the same treatment did not impair the ability of spermatozoa to initiate the acrosome reaction in response to progesterone. Moreover, the preincubation with pertussis toxin did not modify the changes in the intracellular concentration of calcium ions occurring after progesterone addition. These data suggest that different physiological stimuli may utilize different signal transduction pathways to induce the human sperm acrosome reaction.

Fast acrosome reaction measure: a highly sensitive method for evaluating stimulus-induced acrosome reaction

OBJECTIVE

To test a new method for evaluation of stimulus-induced acrosome reaction (AR). To determine whether this method, based on the definition of a specific staining pattern of recently reacted spermatozoa, brings an advantage of increased sensitivity as compared with a standard procedure.

DESIGN

The hypothesis that a specific staining pattern with fluorescein-labeled Pisum sativum agglutinin corresponds to recently acrosome-reacted spermatozoa was tested by analyzing the frequency of this pattern at different time points after addition of ionophore A23187, an artificial AR inducer. The AR results obtained with a new method based on this relationship were compared with those obtained with a standard method of AR evaluation.

SETTING

Private hospital, public research center, and a university-based research laboratory.

PARTICIPANTS

Healthy sperm donors.

MAIN OUTCOME MEASURE

Changes in the frequency of specific sperm-staining patterns.

RESULTS

A specific sperm-staining pattern with P. sativum agglutinin was shown to be associated with a recently occurred AR, whereas the absence of staining was typical of reactions having occurred a longer time ago. This phenomenon was used to define a formula for fast AR measure after stimulus addition. An increased sensitivity provided by this formula as compared with a standard evaluation was demonstrated.

CONCLUSIONS

Fast AR measure is a simple, easy-to-perform method for AR evaluation. It is particularly suitable for testing the effects of rapidly acting stimuli.

Effects of phosphodiesterase inhibitors caffeine and pentoxifylline on spontaneous and stimulus-induced acrosome reactions in human sperm

OBJECTIVE

To determine whether the phosphodiesterase inhibitors caffeine and pentoxifylline influence the acrosome reaction in the conditions in which they are currently used as sperm movement enhancers.

DESIGN

The frequency of acrosome reaction occurring spontaneously in capacitating media or induced by physiological (follicular fluid [FF]) and artificial (ionophore A23187) stimuli was compared in the presence and absence of the phosphodiesterase inhibitors.

SETTING

Private hospital and research laboratory.

PATIENTS, PARTICIPANTS

Patients undergoing routine semen examination before in vitro fertilization (no pathology detected) and healthy sperm donors.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE

Percentage of acrosome-reacted sperm determined with the use of fluorescein-labeled Pisum sativum agglutinin as acrosomal stain.

RESULTS

Caffeine alone augmented the frequency of acrosome reaction, but this effect was not observed with pentoxifylline alone. However, pentoxifylline increased sperm responsiveness to the acrosome reaction-inducing stimuli, FF and ionophore A23187.

CONCLUSIONS

The promotion of spontaneous acrosome reaction may counteract the benefits from application of caffeine as motility stimulant. On the other hand, the sensitization to physiological acrosome reaction stimuli is expected to contribute to the improvement of sperm fertilizing ability by pentoxifylline and make this drug a potential candidate for the treatment of acrosome reaction anomalies.

Sperm plasma membrane integrity measurement: a combined method

Sperm plasma membrane characteristics were measured by a combined method consisting of the hypo-osmotic swelling test and staining with either the eosine Y (HOS-eosine test) or propidium iodide dye (HOS-propidium test). Sperm samples were washed and resuspended in BWW medium (fraction I). Aliquots of the washed spermatozoa were treated by a swim-up technique to select motile spermatozoa (fraction II). After separation of motile cells, residual sperm pellets were treated separately (fraction III). These three fractions were subjected to the hypo-osmotic swelling test, lipid peroxidation measurement, and the HOS-eosine and HOS-propidium tests. The HOS-eosine test makes it possible to distinguish 4 types of spermatozoa: type 1: HOS+/eosine-; type 2: HOS-/eosine-; type 3: HOS-/eosine+ and type 4: HOS+/eosine+ (Fig. 1). HOS-propidium test shows equal results as HOS-eosine test. Fraction I spermatozoa showed 55.2 +/- 3.6% type 1; 12.6 +/- 1.0 type 2; 28.0 +/- 2.9 type 3; and 4.2 +/- 0.6 type 4 cells. Fraction II spermatozoa were characterized by high percentages of type 1 cells, low percentages of types 3 and 4, and very low values of lipid peroxidation (5 times smaller than fraction I). Fraction III showed a low percentage of type 1, a high percentages of the other types, and an enhanced value of lipid peroxidation (2 times higher than fraction I). The prognostic value of the HOS-eosine test was evaluated in an IVF programme. Preliminary results show that a high incidence of types 2 and 4 spermatozoa is often associated with fertilization failure.

Selective expression of a progesterone receptor on the human sperm surface

OBJECTIVE

To visualize progesterone (P) binding sites on the sperm surface, examine the relationship between hormone binding and hormone action (acrosome reaction), and determine the size of the hormone-responsive sperm subpopulation.

DESIGN

Kinetic analysis of P binding was combined with the assessment of the hormone effect using a fluorescent acrosomal marker.

SETTING

Private hospital, medical research center, and a university-based andrological laboratory.

PATIENTS, PARTICIPANTS

Sperm samples were from healthy volunteers with normal spermiogram values.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Progesterone binding was analyzed by fluorescence microscopy and flow cytometry using P coupled to fluorescein isothiocyanate-labeled bovine serum albumin. Tetramethylrhodamine isothiocyanate-labeled Pisum sativum agglutinin was used as acrosomal marker in double-labeling experiments.

RESULTS

After in vitro capacitation, only few spermatozoa (approximately 10%) were able to bind P to the cell surface, but most of these cells subsequently generated the acrosome reaction in response to hormone binding.

CONCLUSIONS

The expression of P receptor sites on the human sperm surface is a major factor controlling the P-induced acrosome reaction. Further studies are warranted to explore if defective expression of the receptor can compromise fertility.