Altered luteal expression patterns of genomic and non-genomic progesterone receptors in bitches at different reproductive states

The binding of steroid hormones to their specific receptors is necessary to exert their effects on target cells. Progesterone (P4), a steroid hormone, carries out its effects through both genomic and non-genomic (the cell membrane-associated) receptors. This study aimed to ascertain luteal expression patterns of genomic and non-genomic progesterone receptors in bitches in physiological (early dioestrus and early pregnant) and pathological (pyometra) reproductive states. Luteal tissue was collected from the bitches at early dioestrus (ED, n = 5), early pregnant (EP, n = 5), and pyometra (PY, n = 5). The expression profiles of Steroidogenic Acute Regulator Protein (STAR), Progesterone Receptor (PGR), Membrane Progestin Receptors (PAQR5, PAQR7 and PAQR8), and Progesterone Membrane Components (PGMRC1 and PGMRC2) were examined at the mRNA levels using Real-Time Polymerase Chain Reaction (RT-PCR). Protein levels of PGR, PGMRC1 and PGMRC2 were detected by western blotting (WB). The STAR expression was found in all groups, with a statistical difference observed between EP and PY groups (P < 0.05). The protein level of PGR was determined to be highest in the EP group and lowest in the PY group. The expression of PAQR8 increased in the EP group (P < 0.05). The PAQR5 exhibited high expression in the EP group and low expression in the PY group (P < 0.05). PGRMC1 was more elevated in the EP group and lower in the PY group (P < 0.05). Protein levels of PGMRC1 and PGMRC2 were also observed at the highest expression in EP group. According to the altered expression profiles for examined receptors, we suggest that those progesterone receptors have roles in early pregnancy or pyometra in bitches.

An investigation of the distributions of ferroptosis and necroptosis mediators in the maternal-fetal interface at different days of rat pregnancy

Ferroptosis and necroptosis are recognized as playing major roles in the regulation of various physiological processes. However, the physiological role of the cell death mediated by these two pathways in the developmental process has not yet been clearly established. This study investigated ferroptosis and necroptosis signalling pathways in maternal-fetal tissue in the different gestational days (GD) of rat pregnancy using immunohistochemical and western blot methods in order to fill this gap. Twenty-four female Wistar albino rats were mated and divided into three groups. Maternal-fetal tissue samples were collected on GD 5, 12 and 19 of pregnancy. Expression and total protein levels of the markers glutathione peroxidase-4, soluble transporter family 7 member 11, transferrin receptor, receptor-interacting serine/threonine-protein kinase 1, receptor-interacting serine/threonine-protein kinase 3 and mixed lineage kinase domain-like protein were investigated on both the maternal and fetal surfaces of the placenta using immunohistochemical and western blot methods. The results showed varying levels of protein expression of both ferroptosis and necroptosis mediators in the GD 5, 12 and 19 of pregnancy. Immunohistochemical analyses revealed that these mediators were located on both the maternal (decidua and metrial gland) and fetal surfaces (labyrinth zone, yolk sac and basal zone) and that their expression levels changed in the different GD. The findings revealed the existence of important ferroptosis and necroptosis pathway mediators in rat maternal-fetal tissue. These results may provide a molecular framework for a better understanding of the communication between the placenta, decidua and fetus during the developmental process.

An investigation of the endoplasmic reticulum stress in obesity exposure in the prenatal period

OBJECTIVES

Exposure to maternal obesity has been shown to make offspring more prone to cognitive and metabolic disorders later in life. Although the underlying mechanisms are unclear, the role of endoplasmic reticulum (ER) stress in the fetal programming process is remarkable. ER stress can be activated by many chronic diseases, including obesity and diabetes. Therefore, our study aimed to investigate the role of ER stress caused by maternal diet-induced obesity in the offspring hippocampus. We also evaluated the protective effect of N-acetylcysteine (NAC) against ER stress.

METHODS

A rat obesity model was created by providing a high-fat (60 % kcal) diet. N-acetylcysteine (NAC) was administered at a dosage of 150 mg/kg via the intragastric route. The animals were mated at the age of 12 weeks. The same diet was maintained during pregnancy and lactation. The experiment was terminated on the postnatal 28th day, and the offspring's brain tissues were examined. Immunohistochemical staining for ER stress markers was performed on sections taken from tissues after routine histological procedures.

RESULTS

The results revealed increased GRP78, PERK, and eIF2α immunoreactivities in the hippocampal dentate gyrus (DG) and cornu ammonis 1 (CA1) regions in the obese group offspring, while the expression of those markers in those regions normalized with NAC supplementation (p < 0.01). Statistical analysis of XBP1 immunoreactivity H-scores revealed no difference between the study groups (p > 0.05).

DISCUSSION

These results suggest that exposure to obesity during the prenatal period may cause increased ER stress in hippocampal neurons, which have an important role in the regulation of learning, memory and behavior, and this may contribute to decreased cognitive performance. On the other hand, NAC stands out as an effective agent that can counteract hippocampal ER stress.

Oleuropein Mitigates Acrylamide-Induced Nephrotoxicity by Affecting Placental Growth Factor Immunoactivity in the Rat Kidney

OBJECTIVE

Oleuropein is one of the main components of the antioxidant properties of olive leaves. Placental growth factor is an important regulator in angiogenesis and inflammation, its levels being variable in pathological conditions. In this study, we aimed to examine changes in placental growth factor expression and the effect of oleuropein, found in olive leaves, in rats exposed to acrylamide nephrotoxicity.

MATERIAL AND METHODS

Twenty-four male Wistar albino rats were allocated into 4 groups. The control group received saline solution only. The oleuropein group received oleuropein (4.2 mg/kg), the acrylamide group received acrylamide (5 mg/kg), and the acrylamide and oleuropein group received acrylamide (5 mg/kg) and oleuropein (4.2 mg/kg). All substances were administered via gastric gavage for 21 days. Kidney tissues were removed at the end of the study and subjected to histopathological, stereological, and immunohistochemical procedures.

RESULTS

Histopathological examination revealed dilatation, vacuolization, and degeneration in the proximal and distal tubules and increased placental growth factor immunoreactivity in the acrylamide group. Cavalieri volume analysis revealed increased cortex, distal, and proximal tubule volumes (P < .01).

CONCLUSION

Oleuropein significantly attenuated acrylamide-induced kidney injury by altering placental growth factor immunoreactivity. Placental growth factor immunoreactivity can be used as a marker of acrylamide nephrotoxicity, and oleuropein may counteract acrylamide-induced kidney injury.

Expression of placental growth factor and a disintegrin and metalloprotease with a thrombospondin type motifs 1-4-8 during the three trimesters of rat pregnancy at the maternal-fetal interface

The functional roles of the a disintegrin and metalloprotease with a thrombospondin type motifs (ADAMTS) gene family in reproductive physiology, reproductive organs developments and adult reproductive health are still under investigation. The expression of the anti-angiogenic proteases ADAMTS-1, ADAMTS-4 and ADAMTS-8 in placental angiogenesis at various stages of pregnancy also remains unclear. The purpose of this study was therefore to determine the localization and expression of the ADAMTS-1, ADAMTS-4 and ADAMTS-8 proteins during the three stages of pregnancy in rats. Maternal-fetal tissue samples were collected on Days 5, 12 and 19 of each trimester, corresponding to the first, second and third trimesters. The expression of placental growth factor (PlGF) and ADAMTS-1, ADAMTS-4 and ADAMTS-8 at the maternal-fetal interface was examined using immunohistochemistry and western blot at three distinct phases of pregnancy. ADAMTS-1, ADAMTS-4 and ADAMTS-8 were detected in all three trimesters of pregnancy. The relative amount of PIGF increased in the first trimester and decreased significantly in the third trimester (p < 0.05). The expression of ADAMTS-1 and ADAMTS-4 was significantly higher in the second (p < 0.05) and third trimesters (p < 0.01) compared to the first trimester. However, no statistically significant change was observed in ADAMTS-8 expression between trimesters. The ADAMTS exhibiting the highest expression during the first trimester was ADAMTS8. These findings indicate that the expression of ADAMTS-1, ADAMTS-4 and ADAMTS-8 in the three different stages of rat pregnancy may be involved in the modulation of decidualization, morphogenesis and angiogenesis. Periodic changes in ADAMTS expression are thought to be regulated by gonadal steroids.

Expression of ADAMTS 1-4-8 and placental growth factor in ovary and oviduct during pregnancy in the first trimester

A Disintegrin and Metalloprotease Domains with Thrombospondins Motifs (ADAMTS), proteinases responsible for the destruction of extracellular matrix structures, have essential roles in the physiological and pathological processes of the female reproductive system, which is a dynamic structure. This study aimed to evaluate the immunoreactivity of placental growth factor (PLGF) and ADAMTS' (1, -4, and -8) in the ovary and oviduct during pregnancy in the first trimester. Our findings suggest a predominant role of ADAMTS-4 and ADAMTS-8 as proteoglycan-degrading enzymes from the ADAMTS-1 in the first trimester. As an angiogenic factor, PLGF showed more immunoreactivity than ADAMTS-1 in the ovary. This study provides the first evidence that ADAMTS-4 and ADAMTS-8 are more expressed in ovarian cells and follicles at different developmental stages during the first trimester of pregnancy than ADAMTS-1. Consequently, we suggest that ADAMTSs and PLGF act together and may exert specific effects on the formation, stabilisation, and function (or a combination thereof) of the matrix surrounding and protecting the follicles.

Protective and therapeutic role of melatonin against tunicamycin-induced ER stress in testicular tissue of rats

OBJECTIVES

This study aimed to investigate the possible consequences of administering exogenous melatonin as prevention or treatment against tunicamycin-induced endoplasmic reticulum (ER) stress in the testicular tissue of rats.

MATERIALS AND METHODS

In this study, 42 adult Sprague Dawley rats, randomly divided into seven equal groups, were administered intraperitoneal tunicamycin to induce ER stress. Both prophylactic (PMel) and therapeutic melatonin (TMel) groups were administered melatonin for seven days. ER stress in the cell was detected through immunohistochemical and molecular analyses using GPR78 expression.

RESULTS

Increased oxidant levels and apoptosis rates were shown in testicular tissue because of ER stress. The sections in the melatonin-administered and control groups were similar, with melatonin-administered groups showing an increase in the antioxidant ratio. Histometric examinations revealed both TMel and melatonin applications reduced the diameter of the tubules. However, immunohistochemical and molecular analyses showed that PMel administration decreased the concentration of GRP78 more effectively than TMel.

CONCLUSION

Applying melatonin prior to cell damage occurrence can be recommended for its effectiveness in protecting from tunicamycin-induced ER stress.

The role of Aβ in Alzheimer's Disease as an Evolutionary Outcome of Optimized Innate Immune Defense

Alzheimer's Disease is a progressive manifestation of aging associated with accumulated Amyloid β. It remains frustratingly unclear why this protein accumulates and how it contributes to Alzheimer's Disease pathology. In one recent hypothesis, Amyloid β is suggested to function as an antimicrobial peptide in innate immune defense within the brain, where Amyloid β gains toxicity when it becomes abundant. This essay proposes an evolutionary explanation for why Amyloid β expression is regulated at an optimum based on its function as a defense and how this leads to disease. Among its potential physiological functions, Amyloid β confers benefits to reduce direct pathogen damage while this simultaneously entails cellular cost of defense. Optimal Amyloid β expression occurs when the gain in fitness from an incremental increase is balanced by the marginal cost of this increase. It proposes that natural selection acting upon the young favored systems to maintain Amyloid β at an optimal level through mechanisms that induce the defense and repress its expression. With age, the force of natural selection declines and permits mechanisms of negative feedback repression to degenerate. Consequently, Amyloid β is expressed beyond its optimum. Age also elevates cumulative pathogen exposure, reduces pathogen barriers and reactivates latent pathogens. The net effect is elevated, chronic induction of Amyloid β in the brain. The model recommends attention to innate immune negative regulation in the brain to discover ways to restore these functions toward a youthful state in the elderly.

Cough reflex sensitivity and fractional exhaled nitric oxide in children with asthma

Individual studies have suggested the utility of fractional exhaled nitric oxide (FeNO) measurement in detecting cough-variant asthma and eosinophilic bronchitis in patients with chronic cough. The aim of this study was to clarify a correlation of cough reflex sensitivity and fractional exhaled nitric oxide in asthmatic children. 25 children with asthma and 15 controls were submitted to cough reflex sensitivity measurement - capsaicin aerosol in doubling concentrations (from 0.61 to 1250 micromol/l) was inhaled by a single breath method. Concentrations of capsaicin causing two (C2) and five coughs (C5) were reported. Fractional exhaled nitric oxide (FeNO) measurement was included. Asthmatic children' (11 boys and 14 girls, mean age 9+/-1 years) and control group (unconfirmed diagnosis of asthma) (6 boys and 9 girls, mean age 8+/-1 years) were included into the study. FeNO vs. C2 in asthma (Spearman´s rank correlation: -0.146, p=0.49); FENO vs. C5 in asthma (Spearman´s rank correlation: -0.777, p=0.71). We found that there is no correlation between cough reflex sensitivity and fractional exhaled nitric oxide either in children with asthma or in the control group.

Relationship between cough reflex sensitivity and body mass index in children with chronic cough - a pilot study

Obesity is characterized by chronic, low-grade systemic inflammation. Obesity may also be associated with chronic cough. The aim of this pilot study was to clarify relation of cough reflex sensitivity and body mass index (BMI) in children with chronic cough. Altogether 41 children having symptoms of chronic cough were submitted to cough reflex sensitivity measurement. We assessed the relation of cough reflex sensitivity (CKR) due to BMI. Cough reflex sensitivity was defined as the lowest capsaicin concentration which evoked two (C2) or five (C5) coughs. Capsaicin aerosol in doubling concentrations (from 0.61 to 1250 micromol/l) was inhaled by a single breath method (KoKo DigiDoser; nSpire heath Inc, Louisville, CO, USA), modified by the addition of an inspiratory flow regulator valve (RIFR; nSpire heath Inc, Louisville, CO, USA). BMI was calculated. Pulmonary function was within normal range. Concentrations of capsaicin causing two (C2) and five coughs (C5) were reported. Children (22 boys and 19 girls, mean age 6.8 years) cough reflex sensitivity (median, with the Inter-Quartile Range) for C2 was 19.5 (73.4) micromol/l; for C5 it was 78.1 (605.5) micromol/l. We have noticed statistically significant relation of the cough reflex sensitivity (C5) and body mass index (P<0.0001); however, the effect size was small, R2=0.03. Increase of body mass index in one unit is associated with -34.959 micromol/l decrease of C5. We did not find a statistically significant relation between C2 and BMI (P=0.41). The median value of CKR (C2) in boys is not statistically significantly different than the median value of CKR (C2) in girls (P-value 0.5). The median value of CKR (C5) in boys is not statistically significantly different than the median value of CKR (C5) in girls (P-value 0.5). Increase of body mass index in children suffering from chronic cough relates to decrease of cough reflex sensitivity (C5 value).

Studies on the regulation of transient lower esophageal sphincter relaxations (TLESRs) by acid in the esophagus and stomach

Transient lower esophageal sphincter relaxation (TLESR) is the major mechanism of gastroesophageal reflux, but the regulation of TLESR by stimuli in the esophagus is incompletely understood. We have recently reported that acid infusion in the esophagus substantially (by 75%) increased the number of meal-induced TLESR in healthy subjects. We concluded that the TLESR reflex triggered by gastric distention with meal was enhanced by the stimulation of esophageal nerves by acid. However, the possibilities that the acid infused into the esophagus acts after passing though lower esophageal sphincter in stomach to enhance TLESR, or that the acid directly initiates TLESR from the esophagus were not addressed. Here, we evaluated the effect of acid infusion into the proximal stomach on meal-induced TLESR (study 1) and the ability of acid infusion into the esophagus to initiate TLESR without prior meal (study 2). We analyzed TLESRs by using high-resolution manometry in healthy subjects in paired randomized studies. In study 1, we found that acid infusion into the proximal stomach did not affect TLESRs induced by standard meal. The number of meal-induced TLESRs following the acid infusion into the proximal stomach was similar to the number of meal-induced TLESRs following the control infusion. In study 2, we found that acid infusion into the esophagus without prior meal did not initiate TLESRs. We conclude that the increase in the meal-induced TLESRs by acid in the esophagus demonstrated in our previous study is not attributable to the action of acid in the stomach or to direct initiation of TLESR from the esophagus by acid. Our studies are consistent with the concept that the stimuli in the esophagus can influence TLESRs. The enhancement of TLESR by acid in the esophagus may contribute to pathogenesis of gastroesophageal reflux in some patients.

Mechanisms of the adenosine A2A receptor-induced sensitization of esophageal C fibers

Clinical studies indicate that adenosine contributes to esophageal mechanical hypersensitivity in some patients with pain originating in the esophagus. We have previously reported that the esophageal vagal nodose C fibers express the adenosine A2A receptor. Here we addressed the hypothesis that stimulation of the adenosine A2A receptor induces mechanical sensitization of esophageal C fibers by a mechanism involving transient receptor potential A1 (TRPA1). Extracellular single fiber recordings of activity originating in C-fiber terminals were made in the ex vivo vagally innervated guinea pig esophagus. The adenosine A2A receptor-selective agonist CGS21680 induced robust, reversible sensitization of the response to esophageal distention (10-60 mmHg) in a concentration-dependent fashion (1-100 nM). At the half-maximally effective concentration (EC50: ≈3 nM), CGS21680 induced an approximately twofold increase in the mechanical response without causing an overt activation. This sensitization was abolished by the selective A2A antagonist SCH58261. The adenylyl cyclase activator forskolin mimicked while the nonselective protein kinase inhibitor H89 inhibited mechanical sensitization by CGS21680. CGS21680 did not enhance the response to the purinergic P2X receptor agonist α,β-methylene-ATP, indicating that CGS21680 does not nonspecifically sensitize to all stimuli. Mechanical sensitization by CGS21680 was abolished by pretreatment with two structurally different TRPA1 antagonists AP18 and HC030031. Single cell RT-PCR and whole cell patch-clamp studies in isolated esophagus-specific nodose neurons revealed the expression of TRPA1 in A2A-positive C-fiber neurons and demonstrated that CGS21682 potentiated TRPA1 currents evoked by allylisothiocyanate. We conclude that stimulation of the adenosine A2A receptor induces mechanical sensitization of nodose C fibers by a mechanism sensitive to TRPA1 antagonists indicating the involvement of TRPA1.

Acid infusion into the esophagus increases the number of meal-induced transient lower esophageal sphincter relaxations (TLESRs) in healthy volunteers

BACKGROUND

Transient lower esophageal sphincter relaxation (TLESR) is the major mechanism of gastroesophageal reflux (GER) but the regulation of TLESR by stimuli in the esophagus is incompletely understood. If stimuli in the esophagus can influence TLESR, then such regulation may perpetuate or limit GER. We addressed the hypothesis that acid in the esophagus enhances TLESRs.

METHODS

We evaluated the effect of acid infusion into the distal esophagus on TLESRs evoked by a standard meal in a paired randomized study in healthy subjects. TLESRs were evaluated by using high resolution manometry (HRM).

KEY RESULTS

We found that acid in the esophagus enhanced meal-induced TLESRs. Compared to control infusion the number of TLESRs (median [interquartile range]) was increased during 2 h following the acid infusion (11 [9-14] vs 17 [12.5-20], p < 0.01). The average duration of individual TLESRs was not affected. The time-course analysis revealed that a robust increase in TLESRs occurred already in the first hour when the number of TLESRs nearly doubled (6 [5.5-7.5] vs 11 [7.5-12.5], p < 0.05). In contrast to the enhancement of TLESRs, the number of swallows was not changed.

CONCLUSIONS & INFERENCES

The acid infusion into the esophagus increases the number of meal-induced TLESRs in healthy subjects. Our results provide evidence for the concept that the stimuli in the esophagus can influence TLESRs. The regulation of TLESR by stimuli in the esophagus may contribute to pathogenesis of GER in some patients.

The effects of nasal irritant induced responses on breathing and cough in anaesthetized and conscious animal models

There is little evidence to support the down-regulation of coughing from the nose. The cough response to citric acid (CA) was studied in anesthetized and conscious guinea pigs after nasal pretreatment with saline, 1% DMSO, allylisothiocyanate (TRPA1 agonist) and allylisothiocyanate +AP-18 (TRPA1 antagonist). Cough was induced by adding citric acid (CA) to the tracheal perfusion in anaesthetized animals, or by inhaling 0.4M CA in conscious animals. The cough response was counted from the dose response curves, airflow traces and cough sound analysis. In conscious animals, nasal allylisothiocyanate induced reproducible, dose dependent nasal symptoms and a significant drop in respiratory rate. Cough induced by CA was suppressed after nasal allylisothiocyanate (p<0.05), and this effect was prevented by AP-18 (1mM). In anaesthetized animals, nasal allylisothiocyanate induced a significant drop in respiratory rate. Cough induced subsequently by CA was suppressed when compared to baseline and vehicle responses (p<0.05). The reasons for the suppression of CA induced cough by TRPA1 agonist applied to the nose are not clear and remain to be elucidated.

The role of trigeminal nasal TRPM8-expressing afferent neurons in the antitussive effects of menthol

The cold-sensitive cation channel TRPM8 is a target for menthol, which is used routinely as a cough suppressant and as an additive to tobacco and food products. Given that cold temperatures and menthol activate neurons through gating of TRPM8, it is unclear how menthol actively suppresses cough. In this study we describe the antitussive effects of (-)-menthol in conscious and anesthetized guinea pigs. In anesthetized guinea pigs, cough evoked by citric acid applied topically to the tracheal mucosa was suppressed by menthol only when it was selectively administered as vapors to the upper airways. Menthol applied topically to the tracheal mucosa prior to and during citric acid application or administered continuously as vapors or as an aerosol to the lower airways was without effect on cough. These actions of upper airway menthol treatment were mimicked by cold air delivered to the upper airways but not by (+)-menthol, the inactive isomer of menthol, or by the TRPM8/TRPA1 agonist icilin administered directly to the trachea. Subsequent molecular analyses confirmed the expression of TRPM8 in a subset of nasal trigeminal afferent neurons that do not coincidently express TRPA1 or TRPV1. We conclude that menthol suppresses cough evoked in the lower airways primarily through a reflex initiated from the nose.

The neural crest- and placodes-derived afferent innervation of the mouse esophagus

BACKGROUND

The mouse is an invaluable model for mechanistic studies of esophageal nerves, but the afferent innervation of the mouse esophagus is incompletely understood. Vagal afferent neurons are derived from two embryonic sources: neural crest and epibranchial placodes. We hypothesized that both neural crest and placodes contribute to the TRPV1-positive (potentially nociceptive) vagal innervation of the mouse esophagus.

METHODS

Vagal jugular/nodose ganglion (JNG) and spinal dorsal root ganglia (DRG) neurons were retrogradely labeled from the cervical esophagus. Single cell RT-PCR was performed on the labeled neurons.

KEY RESULTS

In the Wnt1Cre/R26R mice expressing a reporter in the neural crest-derived cells we found that both the neural crest- and the placodes-derived vagal JNG neurons innervate the mouse esophagus. In the wild-type mouse the esophageal vagal JNG TRPV1-positive neurons segregated into two subsets: putative neural crest-derived purinergic receptor P2X(2) -negative/preprotachykinin-A (PPT-A)-positive subset and putative placodes-derived P2X(2) -positive/PPTA-negative subset. These subsets also segregated by the expression of TrkA and GFRα(3) in the putative neural crest-derived subset, and TrkB in the putative placodes-derived subset. The TRPV1-positive esophageal DRG neurons had the phenotype similar to the vagal putative neural crest-derived subset.

CONCLUSIONS & INFERENCES

The TRPV1-positive (potentially nociceptive) vagal afferent neurons innervating the mouse esophagus originate from both neural crest and placodes. The expression profile of the receptors for neurotrophic factors is similar between the neural crest-derived vagal and spinal nociceptors, but distinct from the vagal placodes-derived nociceptors.

Workshop: tuning the 'cough center'

The Workshop considered the mechanisms whereby the 'cough center' could be tuned by various afferent inputs. There were particular presentations on the effects of inputs from the nose, mouth, respiratory tract and lungs, cerebral cortex, somatic tissues and the pharynx. From all these sites cough induced from the lungs could be increased or decreased in its strength or modified in its pattern. Thus 'tuning' of cough could be due to the interaction of afferent inputs, or to the sensitization or desensitization of brainstem neural pathways. The pattern of response depended on the 'type' of cough being studied and, in some instances, on the timing of the sensory input into the brainstem. Cough inputs could also affect various 'non-cough' motor outputs from the brain, although this was not the main theme of the Workshop. The main conclusion was that cough is not a stereotyped output from the medullary 'cough center', but that its pattern and strength depend on many afferent inputs acting on the 'cough center'.

Distinction of cough from other sounds produced by daily activities in the upper airways

OBJECTIVES

The aim of this study was to validate the successfulness of our developed system for distinction between cough and other sounds which are present in daily human activities from the upper airways.

BACKGROUND

To date, methods used for monitoring of cough sound were primarily subjective. A reliable measure of cough is needed so that the severity of cough in various patients and the effectiveness of treatment can be assessed.

METHODS

Sounds of induced cough and sneezing, voluntary throat and nasopharynx clearing, forced ventilation and laughing, snoring, eructation, loud swallowing, and nasal blowing were studied. Characteristics of the sound events in 20 volunteers were calculated using the time-domain, spectral and non-linear analysis. The classification tree was constructed for classification between cough and non-cough sounds. We have validated the usefulness of our developed algorithm against subjective cough counts, which were performed by two trained observers.

RESULTS

The value of sensitivity for distinction between cough and other sounds was 86% and the value of specificity was 91%. The value of sensitivity for distinction between voluntary and induced cough sounds was 96% and specificity was 43%. The value of sensitivity between cough sounds and voluntary throat clearing was 96% and specificity was 85%. The value of sensitivity between cough sounds and induced sneezing was 95% and specificity was 93%.

CONCLUSION

We have developed an algorithm for distinction between cough and other sounds with a relatively high degree of accuracy (Tab. 1, Fig. 5, Ref. 15).

The kinematics of the Zagros Mountains (Iran)

We present a synthesis of recently conducted tectonic, global positioning system (GPS), geomorphological and seismic studies to describe the kinematics of the Zagros mountain belt, with a special focus on the transverse right-lateral strike-slip Kazerun Fault System (KFS). Both the seismicity and present-day deformation (as observed from tectonics, geomorphology and GPS) appear to concentrate near the 1000 m elevation contour, suggesting that basement and shallow deformation are related. This observation supports a thick-skinned model of southwestward propagation of deformation, starting from the Main Zagros Reverse Fault. The KFS distributes right-lateral strike-slip motion of the Main Recent Fault onto several segments located in an en echelon system to the east. We observe a marked difference in the kinematics of the Zagros across the Kazerun Fault System. To the NW, in the North Zagros, present-day deformation is partitioned between localized strike-slip motion on the Main Recent Fault and shortening located on the deformation front. To the SE, in the Central Zagros, strike-slip motion is distributed on several branches of the KFS. The decoupling of the Hormuz Salt layer, restricted to the east of the KFS and favouring the spreading of the sedimentary cover, cannot be the only cause of this distributed mechanism because seismicity (and therefore basement deformation) is associated with all active strike-slip faults, including those to the east of the Kazerun Fault System.

Influence of stimulation of nasal afferents on expiration reflex evoked from vocal folds

Cough and sneezing are upregulated during the upper airway diseases, most likely to enhance airway defense. The aim of this study was to assess the expiration reflex (ER), another expulsive defensive airway reflex, during allergic rhinitis (AR) and intranasal (i.n.) capsaicin challenge. Thirty male guinea pigs, sensitized to ovalbumin were used in the study. They were divided into 3 groups of 10 animals each: AR group (i.n. ovalbumin), capsaicin group (i.n. capsaicin 50 microM, 15 microl), and controls without any challenge. The animals were anesthetized with urethane (1.1 mg/kg) and allowed to breath spontaneously via tracheostomy. Metal canula was introduced into the right hemithorax to assess intrapleural pressure. ER was elicited by mechanical stimulation of the vocal folds using a thin nylon loop introduced upwards via tracheostomy. Maximal expiratory effort of ER (MEE) and the count of post-ER laryngeal coughs were evaluated. Mechanical stimulation of the vocal folds in controls produced isolated ER. They were followed by post-ER cough only in 11% of provocations. AR and capsaicin challenge increased MEE compared with that in controls (P<0.05). In these two groups of animals, the ER was followed by post ER-cough in 75% of provocations. The count of post-ER coughs in the group order control/AR/capsaicin was 0-2/2-4/1-3, respectively; P<0.05). The ER from the vocal folds is upregulated in a similar manner as is cough and sneeze. The central neuronal mechanisms are proposed to mediate this effect, but the spread of inflammation from upper airways to the larynx, verified histologically in the present study, may contribute as well.

Convergence of nasal and tracheal neural pathways in modulating the cough response in guinea pigs

In the present study we investigated the possibility of central convergence of neural pathways coming from distant anatomical regions in modulating the cough response. We addressed this issue by inducing cough from the tracheo-bronchial region on the background of capsaicin-stimulated and mesocain-blocked nasal mucosa in 14 anesthetized guinea pigs. The control group consisted of 6 guinea pigs in which the active agents, capsaicin and mesocain, were substituted for by inert physiological saline. All animals were tracheostomized, and the larynx was disconnected from the proximal part of the trachea with preserved innervations, and all were subjected to the same protocol. Cough, induced by mechanical irritation of the tracheo-bronchial mucosa, was elicited three times: in the control condition, after intranasal capsaicin challenge, and after another capsaicin challenge preceded by intranasal instillation of a local anesthetic, mesocain. The main finding of the study was that the number of cough efforts per bout, assessed from positive deflections on the intrapleural pressure recordings, was significantly enhanced by intranasal capsaicin challenge and this effect was reversed by intranasal pretreatment with the anesthetic mesocain [2.1 +/-0.2 (control) vs. 3.5 +/-0.4 (capsaicin) vs. 2.2 +/-0.2 (capsaicin after mesocain) (P<0.01)], with no appreciable changes in the magnitude of cough efforts. The cough response in the control group remained unchanged. We conclude that tracheo-bronchial cough may be modified by neural sensory input to the brain coming from nasal mucosa. Therefore, cough reflex is subject to central convergence of peripheral neural pathways originating at distant anatomical locations.

Cough reflex sensitivity is increased in the guinea pig model of allergic rhinitis

Increased cough reflex sensitivity is found in patients with allergic rhinitis and may contribute to cough caused by rhinitis. We have reported that cough to citric acid is enhanced in the guinea pig model of allergic rhinitis. Here we address the hypothesis that the cough reflex sensitivity is increased in this model. The data from our previous studies were analyzed for the cough reflex sensitivity. The allergic inflammation in the nose was induced by repeated intranasal instillations of ovalbumin in the ovalbumin-sensitized guinea pigs. Cough was induced by inhalation of doubling concentrations of citric acid (0.05-1.6 M). Cough threshold was defined as the lowest concentration of citric acid causing two coughs (C2, expressed as geometric mean [95% confidence interval]). We found that the cough threshold was reduced in animals with allergic rhinitis. C2 was 0.5 M [0.36-0.71 M] and 0.15 M [0.1-0.23 M] prior and after repeated intranasal instillations of ovalbumin, respectively, P<0.01, n=36). C2 was not affected in control animals (n=29). We have reported that the selective leukotriene cys-LT1 receptor antagonist montelukast inhibited cough enhancement in this model. We found that this was accompanied by inhibition of the changes in cough reflex sensitivity. C2 was reduced in animals with allergic rhinitis treated orally with vehicle (0.57 M [0.28-1.1] vs. 0.09 M [0.04-0.2 M], P<0.05, n=8), but not in animals treated with montelukast (0.57 M [0.22-1.4 M] vs. 0.52 M [0.17-1.6 M], NS, n=8). We conclude that the cough reflex sensitivity is increased in the guinea pig model of allergic rhinitis. Our results suggest that guinea pig is a suitable model for mechanistic studies of increased cough reflex sensitivity in rhinitis.

Role of gender and pubertal stage on cough sensitivity in childhood and adolescence

Studies in healthy adult volunteers and patients with chronic cough have shown that women have increased cough sensitivity to inhaled tussigenic stimuli, including capsaicin. The explanation for this phenomenon remains unknown, although the influence of pubertal changes (dimensional, hormonal) may play a role. In the present study we set out to examine the effect of the pubertal status on cough reflex sensitivity in a population of male and female children and adolescents. The study consisted of cough reflex sensitivity (CRS) testing, spirometry, and a children-completed pubertal status questionnaire. The inclusion criteria were no current symptoms of respiratory disease, no respiratory infection in the preceding 2 weeks, no allergic disease, and no other disease that could modulate CRS. All children were non-smokers. For assessing the CRS we used a compressed air-driven nebuliser controlled by a dosimeter with an inspiratory flow regulator valve. Each subject inhaled up to 12 capsaicin aerosol concentrations (0.61-1250 micromol/l) during 400 ms at 1 min intervals. CRS was defined as the lowest capsaicin concentration that evoked minimally 2 coughs. 225 children (median age 13 yr, 103 girls/122 boys) were divided according to the pubertal status (prepubertal, early pubertal, and late pubertal) and gender. We found that CRS [geometric mean (95%CI)] was similar in prepubertal and early pubertal girls and boys. However, CRS was significantly higher in late pubertal girls (n=56) than in boys (n=26) [53.57 (35.62-80.64) micromol/l vs. 119.7 (70.74-208.55) micromol/l; respectively; P=0.017]. We conclude that puberty and gender have a significant influence on the cough threshold to capsaicin. It seems, however, hard to determine what factors are responsible for the observed gender differences in cough reactivity adolescents.

Differences in oxidative status, lung function, and pulmonary surfactant during long-term inhalation of medical oxygen and partially ionized oxygen in guinea pigs

Inhalation of partially ionized oxygen may have less adverse effects on lung functions than medical oxygen. Guinea pigs inhaled air, 100% molecular medical oxygen (O(2)mol), partially negatively (O(2)neg) or positively (O(2)posit) ionized oxygen during 17 and 60 h. After 17 h, dityrosines, markers of oxidative injury, in lung homogenate increased in O(2)neg and decreased in O(2)posit groups vs. controls. After 60 h, dityrosines rose after inhalation of O(2)mol and O(2)neg, but not in the O(2)posit group. Lysine-LPO products increased and lung wet/dry weight ratio decreased in O(2)mol and O(2)neg, and not in O(2)posit group. Relative neutrophil count in BALF was elevated in all oxygen-treated groups with lower numbers in O(2)posit vs.O(2)mol and O(2)neg groups. After 60 h, surfactant activity was better in O(2)posit vs. O(2)mol group. In conclusion, long-term inhalation of partially positively ionized oxygen is associated with less oxidative stress, milder lung inflammatory response, and better surfactant activity than molecular or negatively ionized oxygen.

Cough reflex sensitivity testing in in seasonal allergic rhinitis patients and healthy volunteers

Dysfunction of upper and lower airways frequently coexists, and they appear to share key elements of pathogenesis. The interrelationship between upper and lower airway manifestations of allergy remains still incompletely investigated. Little is known about the critical factors that determine airway afferent nerve endings reactivity (cough sensitivity) in patients with allergic rhinitis. Subclinical inflammatory changes within the lower airways and/or chronic upper airway cough syndrome (previously referred to as postnasal drip syndrome) are probably responsible for this effect. The aim of this study was to evaluate capsaicin cough sensitivity in pollen sensitive patients with seasonal allergic rhinitis without treatment out of a grass pollen season time using the European Respiratory Society (ERS) guidelines on the assessment of cough. Cough sensitivity was defined as the lowest capsaicin concentration which evoked two (C2) or five (C5) coughs. Capsaicin aerosol in doubling concentrations (from 0.49 to 1000 micromol/l) was inhaled by a single breath method (KoKo DigiDoser; nSpire heath Inc, Louisville, CO), modified by the addition of an inspiratory flow regulator valve (RIFR; nSpire heath Inc, Louisville, CO). The seasonal rhinitis subjects (5M, 7F; mean age 23 yr) had not been complaining primarily about coughing. Their pulmonary function was within normal range. Concentrations of capsaicin causing two (C2) and five coughs (C5) were reported. Volunteers' (5M, 7F, mean age 23 yr) cough sensitivity (geometric mean and 95 % CI) for C2 was 16.5 (4.1-67.0) micromol/l vs. allergic rhinitis patients' C2 3.5 (1.9 - 6.4) (P= 0.018). Volunteers' C5 was 132.4 (41.3 - 424.5) micromol/l vs. allergic rhinitis patients' C5 13.1 (6.0 - 28.6) micromol/l (P= 0.013). We conclude that airway afferent nerve endings reactivity in pollen sensitive subjects suffering from seasonal allergic rhinitis was significantly increased out of pollen season compared with healthy volunteers.

Distinction between voluntary cough sound and speech in volunteers by spectral and complexity analysis

Objective monitoring of cough sound for extended period is an important step toward a better understanding of this symptom. Because ambulatory cough monitoring systems are not commercially available, we prepared own monitoring system, which is able to distinguish between voluntary cough sound and speech in healthy volunteers. 20-min sound records were obtained using portable digital voice recorder. Characteristics of the sound events have been calculated in time and frequency domains and by a nonlinear analysis. Based on selected parameters, classification tree was constructed for the classification of cough and non-cough sound events. We validated the usefulness of our algorithm developed against manual counts of cough obtained by a trained observer. The median sensitivity value was 100% (the interquartile range was 98-100) and the median specificity was 95% (the interquartile range was 90-97). In conclusion, we developed an algorithm to distinguish between voluntary cough sound and speech with a high degree of accuracy.

Acidification of the oesophagus acutely increases the cough sensitivity in patients with gastro-oesophageal reflux and chronic cough

Gastro-oesophageal reflux disease (GORD) is one of the most common causes of chronic cough; however, the mechanisms by which GOR initiates coughing are incompletely understood. We address the hypothesis that acidification of oesophagus acutely increases the cough reflex sensitivity in patients with GORD and chronic cough. Nine patients with GORD with chronic cough and 16 patients with GORD without cough were recruited. In a randomized double blind study, saline and acid (HCl, 0.1 mol L(-1)) were separately infused into oesophagus via naso-oesophageal catheter. Cough reflex sensitivity to inhaled capsaicin was determined immediately after completion of each infusion. Infusion of acid into oesophagus increased capsaicin cough reflex sensitivity in patients with GORD and chronic cough. In contrast, acid had no effect on the cough sensitivity in patients with GORD without cough. In a separate study, acid infusion into oesophagus did not affect the cough sensitivity in 18 healthy subjects. We conclude that acid in the oesophagus acutely increases the cough reflex sensitivity to capsaicin in patients with GORD and chronic cough. This phenomenon may contribute to the pathogenesis of cough due to GORD.