Relationship between acid neutralization capacity of saliva and gastro-oesophageal reflux

Radiation-associated changes in saliva composition of head and neck cancer patients: A systematic review

Xerostomia is a common radiation-associated toxicity in patients with head and neck cancer. Although several studies examined the decrease in saliva production due to radiotherapy (RT) and investigated the factors associated with this side effect, little is known about the change in radiation-associated saliva composition. This systematic review is the first to summarize existing data and give an overview of the change in pH/buffer capacity, electrolytes, proteins, enzymes, and mucins due to radiation to the salivary glands. Literature search was performed in PubMed and Embase with 47 articles finally eligible for the review, analyzing the saliva composition at several time points before, during and/or after RT, or comparing findings in irradiated patients to a healthy control group. Overall, RT leads to a substantial decrease in salivary pH and buffer capacity. For sodium, chloride and calcium ion, as well as amylase, an increased concentration or activity during RT was reported in most of the studies, followed by a subsequent decrease either already during RT or after the end of treatment. Different trends have been described for the total protein concentration during and after RT. Lactoferrin, however, increased considerably, especially in the first phase of RT. Mucin 5B (MUC5B) concentrations showed a slight increase during RT and concentrations around baseline values again six months post-radiotherapy.

Extracellular acidification attenuates bronchial contraction via an autocrine activation of EP2 receptor: Its diminishment in murine experimental asthma

PURPOSE

Extracellular acidification is a major component of tissue inflammation, including airway inflammation in asthmatics. However, its physiological/pathophysiological significance in bronchial function is not fully understood. Currently, the functional role of extracellular acidification on bronchial contraction was explored.

METHODS

Left main bronchi were isolated from male BALB/c mice. Epithelium-removed tissues were exposed to acidic pH under submaximal contraction induced by 10-5 M acetylcholine in the presence or absence of a COX inhibitor indomethacin (10-6 M). Effects of AH6809 (10-6 M, an EP2 receptor antagonist), BW A868C (10-7 M, a DP receptor antagonist) and CAY10441 (3×10-6 M, an IP receptor antagonist) on the acidification-induced change in tension were determined. The release of prostaglandin E2 (PGE2) from epithelium-denuded tissues in response to acidic pH was assessed using an ELISA.

RESULTS

In the bronchi stimulated with acetylcholine, change in the extracellular pH from 7.4 to 6.8 caused a transient augmentation of contraction followed by a sustained relaxing response. The latter inhibitory response was abolished by indomethacin and AH6809 but not by BW A868C or CAY10441. Both indomethacin and AH6809 significantly increased potency and efficacy of acetylcholine at pH 6.8. Stimulation with low pH caused an increase in PGE2 release from epithelium-denuded bronchi. Interestingly, the acidic pH-induced bronchial relaxation was significantly reduced in a murine asthma model that had a bronchial hyperresponsiveness to acetylcholine.

CONCLUSION

Taken together, extracellular acidification could inhibit the bronchial contraction via autocrine activation of EP2 receptors. The diminished acidic pH-mediated inhibition of bronchial tone may contribute to excessive bronchoconstriction in inflamed airways such as asthma.

Hyperresponsiveness to Extracellular Acidification-Mediated Contraction in Isolated Bronchial Smooth Muscles of Murine Experimental Asthma

PURPOSE

Extracellular acidification is a major component of tissue inflammation, including airway inflammation. The extracellular proton-sensing mechanisms are inherent in various cells including airway structural cells, although their physiological and pathophysiological roles in bronchial smooth muscles (BSMs) are not fully understood. In the present study, to explore the functional role of extracellular acidification on the BSM contraction, the isolated mouse BSMs were exposed to acidic pH under contractile stimulation.

METHODS AND RESULTS

The RT-PCR analyses revealed that the proton-sensing G protein-coupled receptors were expressed both in mouse BSMs and cultured human BSM cells. In the mouse BSMs, change in the extracellular pH from 8.0 to 6.8 caused an augmentation of contraction induced by acetylcholine. Interestingly, the acidic pH-induced BSM hyper-contraction was further augmented in the mice that were sensitized and repeatedly challenged with ovalbumin antigen. In this animal model of asthma, upregulations of G protein-coupled receptor 68 (GPR68) and GPR65, that were believed to be coupled with Gq and Gs proteins respectively, were observed, indicating that the acidic pH could cause hyper-contraction probably via an activation of GPR68. However, psychosine, a putative antagonist for GPR68, failed to block the acidic pH-induced responses.

CONCLUSION

These findings suggest that extracellular acidification contributes to the airway hyperresponsiveness, a characteristic feature of bronchial asthma. Further studies are required to identify the receptor(s) responsible for sensing extracellular protons in BSM cells.

SERS active fibers from wet-spinning of alginate with gold nanoparticles for pH sensing

Functional composite fibers were prepared by a wet-spinning method and used for pH sensing based on surface enhanced Raman scattering (SERS). Alginate solution with gold nanoparticles (AuNPs) was spun to fibers that acting as active substrate showed distinct SERS enhancement for low concentrations of dyes (1.0 × 10^-9 M for rhodamine 6G and 1.0 × 10^-8 M for crystal violet). After AuNPs were modified with 4-mercaptopyridine (4-MPY), the as-synthesized composite fibers (AuNPs@4-MPY/Ca-ALG fibers) displayed pH dependent SERS spectra due to the changes of chemical structures of 4-MPY under different pH conditions. The AuNPs@4-MPY/Ca-ALG fibers achieved fast response to the pH changes between 1.00 and 13.00. The flexible composite fibers were woven to a wearable "wrist band", which has potential applications in health monitoring involving pH variation.

Functionalized Mouth-Conformable Interfaces for pH Evaluation of the Oral Cavity

Oral health monitoring is highly desired, especially for in home use, however, current methods are not sensitive enough and technically convoluted for this purpose. This paper presents incorporation of bioactive materials and colorimetric chemical sensors into routinely used oral appliances transforming them into bioresponsive, conformable interfaces. Specifically, endodontic paper points and dental floss can be functionalized to locally sense and monitor pH variations within the oral cavity via color changes. Moreover, edible colorimetric indicators are developed and used to make sensing, edible devices in the form factor of candies that can dynamically and visually respond to acidity changes in saliva. These interfaces would enable early detection of caries (e.g., using dental floss and paper points) providing low-cost point of care devices that respond in real-time by detecting pH variations in biological fluids thus bringing monitoring to home settings .

Flexible potentiometric pH sensors for wearable systems

There is a growing demand for developing wearable sensors that can non-invasively detect the signs of chronic diseases early on to possibly enable self-health management. Among these the flexible and stretchable electrochemical pH sensors are particularly important as the pH levels influence most chemical and biological reactions in materials, life and environmental sciences. In this review, we discuss the most recent developments in wearable electrochemical potentiometric pH sensors, covering the key topics such as (i) suitability of potentiometric pH sensors in wearable systems; (ii) designs of flexible potentiometric pH sensors, which may vary with target applications; (iii) materials for various components of the sensor such as substrates, reference and sensitive electrode; (iv) applications of flexible potentiometric pH sensors, and (v) the challenges relating to flexible potentiometric pH sensors.

Can muscle vibration be the future in the treatment of cerebral palsy-related drooling? A feasibility study

Background: Drooling is an involuntary loss of saliva from the mouth, and it is a common problem for children with cerebral palsy (CP). The treatment may be pharmacological, surgical, or speech-related. Repeated Muscle Vibration (rMV) is a proprioceptive impulse that activates fibers Ia reaching the somatosensory and motor cortex. Aim: The aim of the study is to evaluate the effectiveness of rMV in the treatment of drooling in CP. Design, setting and population: This was a rater blinded prospective feasibility study, performed at the "Gli Angeli di Padre Pio" Foundation, Rehabilitation Centers (Foggia, Italy), involving twenty-two CP patients affected by drooling (aged 5-15, mean 9,28 ± 3,62). Children were evaluated at baseline (T0), 10 days (T1), 1 month (T2) and 3 months (T3) after the treatment. Methods: The degree and impact of drooling was assessed by using the Drooling Impact Scale (DIS), the Drooling Frequency and Severity Scale (DFSS), Visual Analogue Scale (VAS) and Drooling Quotient (DQ). An rMV stimulus under the chin symphysis was applied with a 30 min protocol for 3 consecutive days. Results: The statistical analysis shows that DIS, DFSS, VAS, DQ improved with significant differences in the multiple comparisons between T1 vs T2, T1 vs T3 and T1 vs T4 (p≤0.001). Conclusion This study demonstrates that rMV might be a safe and effective tool in reducing drooling in patients with CP. The vibrations can improve the swallowing mechanisms and favor the acquisition of the maturity of the oral motor control in children with CP.

Human saliva as a diagnostic material

Today blood biochemical laboratory tests are essential elements to the diagnosis and monitoring of the treatment of diseases. However, many researchers have suggested saliva as an preferable diagnostic material. The collection of saliva is simple, painless, cheap and safe, both for patients and medical staff. An additional advantage of saliva is the fact that it may be retrieved several times a day, which makes repeat analysis much easier. Furthermore, saliva has very high durability. Although 94-99% of salivary content is water, saliva also contains numerous cellular elements and many organic and inorganic substances, including most biological markers present in the blood and urine that may be used in the early detection and monitoring of many dental and general diseases.

Children with a Higher Activity of Carbonic Anhydrase VI in Saliva Are More Likely to Develop Dental Caries

OBJECTIVE

This study aimed to analyze the concentration and activity of carbonic anhydrase (CA) VI in the saliva of school children. We investigated the relationship among caries, CA VI concentration/activity, flow rate, pH, and buffering capacity.

MATERIALS AND METHODS

Seventy-four school children were divided into a caries-free group and a caries group. Clinical examinations were conducted by one examiner according to World Health Organization criteria + early caries lesions. Salivary flow rate, pH, and buffering capacity were analyzed. Salivary CA VI concentration and activity were evaluated by ELISA and zymography, respectively. The data were analyzed using Student's t test and the Mann-Whitney test, and Pearson and Spearman correlation analyses were also done. In multivariate modeling, associations between variables were expressed as odds ratios.

RESULTS

The results showed that salivary flow rate, salivary pH, and BC were significantly higher in the saliva of caries-free children. Also, the salivary CA VI concentration was significantly higher in the saliva of caries-free children. The salivary CA VI activity was higher in children with caries. We found a negative correlation between BC and dental caries. Also, in the caries group we found a positive correlation between the concentration and the activity of CA VI and a negative correlation between BC and CA VI activity. A negative correlation between salivary pH and CA VI concentration was observed in the caries-free group. A high activity of CA and a low salivary flow rate were associated with dental caries.

CONCLUSION

These results support the conclusion that dental caries is highly affected by the activity of CA VI in saliva as well as by the salivary flow rate.

An Optical Sensor with Polyaniline-Gold Hybrid Nanostructures for Monitoring pH in Saliva

Saliva contains important personal physiological information that is related to some diseases, and it is a valuable source of biochemical information that can be collected rapidly, frequently, and without stress. In this article, we reported a new and simple localized surface plasmon resonance (LSPR) substrate composed of polyaniline (PANI)-gold hybrid nanostructures as an optical sensor for monitoring the pH of saliva samples. The overall appearance and topography of the substrates, the composition, and the wettability of the LSPR surfaces were characterized by optical and scanning electron microscope (SEM) images, infrared spectra, and contact angles measurement, respectively. The PANI-gold hybrid substrate readily responded to the pH. The response time was very short, which was 3.5 s when the pH switched from 2 to 7, and 4.5 s from 7 to 2. The changes of visible-near-infrared (NIR) spectra of this sensor upon varying pH in solution showed that-for the absorption at given wavelengths of 665 nm and 785 nm-the sensitivities were 0.0299 a.u./pH (a.u. = arbitrary unit) with a linear range of pH = 5-8 and 0.0234 a.u./pH with linear range of pH = 2-8, respectively. By using this new sensor, the pH of a real saliva sample was monitored and was consistent with the parallel measurements with a standard laboratory method. The results suggest that this novel LSPR sensor shows great potential in the field of mobile healthcare and home medical devices, and could also be modified by different sensitive materials to detect various molecules or ions in the future.

The ontogeny of saliva secretion in infants and esophagoprotection

BACKGROUND

Several studies have reported that severe reflux esophagitis is rare in infants despite the well known high occurrence of regurgitation in early infancy. There is evidence of the importance of saliva for the pre-epithelial protection of the esophageal mucosa.

RESULTS

A longitudinal study conducted on healthy infants indicated that the stimulated capacity of saliva secretion (saliva output per kg of body weight) was significantly higher during their first year of age compared to older children and adults. In addition, this secretion pattern was also observed in low weight newborns during the first weeks of life and persisted in infants with severe protein-calorie malnutrition (marasmus).

CONCLUSION

The greater ability to secrete saliva is an important physiological condition that may protect the infant from acid/pepsin aggression to the esophagus during early stages of development.

A nocturnal decline of salivary pH associated with airway hyperresponsiveness in asthma

Salivary pH is associated with esophageal acid reflux and neutralization of esophageal acid. In this study, we assessed the association between nocturnal decline of salivary pH and airway hyperresponsiveness. Salivary pH was serially assessed in 9 patients with mild asthma (7 men and 2 women; mean age 33.3 years; mean %predicted FEV(1.0) 89.4%) and 10 healthy volunteers (6 men and 4 women; mean age 31.2 years) using a pH indicator tape. The buffering capacity of saliva was defined as the median effective dose (ED(50)) for acidification of saliva with 0.01 N HCl, and airway responsiveness was defined as the dose of methacholine producing a 35% fall in Grs (PD(35)-Grs). There was a significant correlation between the values obtained from the pH indicator tape and those obtained from the electrometric pH meter. Using the indicator tape for sequential monitoring, we observed a nocturnal fall (ΔpH) in salivary pH in all subjects. A significant correlation was found between airway hyperresponsiveness (PD(35)-Grs) and either ΔpH or ED(50) in mildly asthmatic patients. Vagal reflux dysfunction might contribute to nocturnal salivary pH as well as to airway hyperresponsiveness in mild asthmatics.

Drooling in cerebral palsy: hypersalivation or dysfunctional oral motor control?

AIM

To investigate whether drooling in children with cerebral palsy (CP) in general and in CP subtypes is due to hypersalivation.

METHOD

Saliva was collected from 61 healthy children (30 males, mean age 9y 5mo [SD 11mo]; 31 females, mean age 9y 6mo [1y 2mo]) and 100 children with CP who drooled (57 males, mean age 9y 5mo [3y 11mo], range 3-19y; 43 females, mean age 10y 1mo [4y 9mo], range 4-19y), of whom 53 had spastic, 42 had dyskinetic, and five had ataxic CP. Almost all children were affected bilaterally, and 90 of them were at Gross Motor Function Classification System levels III or higher. The saliva was collected by the swab saliva collection method. The intensity of drooling was evaluated using the drooling quotient.

RESULTS

No difference was found in the flow rates, age, or sex between healthy children and children with CP who drooled. On additional subgroup analysis, the flow rates of children with dyskinetic CP differed statistically from those of healthy children (submandibular p=0.047, parotid p=0.040).

INTERPRETATION

This study supports the finding in previous studies that no hypersalivation exists in children with CP who drool. Dysfunctional oral motor control seems to be responsible for saliva overflow from the mouth, whereas increased unstimulated salivary flow may occur in children with dyskinetic CP as a result of hyperkinetic oral movements.

Saliva variations in gastro-oesophageal reflux disease

OBJECTIVES

The protective role of saliva in the case of oesophageal exposition to gastric acid has long been studied but some contradictions still remain. The main end-point of this study was to evaluate if a qualitative and quantitative alteration in salivary secretion exists in patients affected by GERD.

METHODS

One hundred and twenty patients (T group) with clinically and endoscopically diagnosed GERD, and 98 healthy subjects (C group) have been evaluated; salivary tests (i.e. basal flow rate, stimulated flow rate, pH, [Na(+)] and [K(+)]) were performed, socio-demographical variables and oral GERD-related symptoms were taken into account. SPSS 10.5 software was used for statistical univariate and multivariate analyses.

RESULTS

GERD patients and controls were found to have a similar basal flow rate but different stimulated salivary function [T group mean value 0.989 ml/min (+/-0.48718) vs. C group 1.2197 ml/min (+/-0.6108), pH [T group mean value 8.935 (+/-0.471) vs. C group 7.879 (+/-0.526)] and a higher K(+) concentration. In GERD patients we also registered a significant association with xerostomia [69/120 (57.5%) vs. 28/98 (28.7%)] and an oral burning sensation [58/120 (48.3%) vs. 19/98 (19.3%)].

CONCLUSIONS

Our findings assess that salivary secretion is altered in GERD patients and highlight the need for further investigations in order to define the role of saliva in the etiopathogenesis of GERD.

Spatiotemporal characteristics of acid refluxate and relationship to symptoms in premature and term infants with chronic lung disease

BACKGROUND AND OBJECTIVES

The prevalence of gastroesophageal reflux (GER) is high among infants with chronic lung disease (CLD), and the associated pathogenic mechanisms are not clear. The relationship of symptoms to the extent or duration of acid reflux events (AREs) is not well known in preterm or term infants. Our aim was to evaluate the relationship between spatial (height) and temporal (duration) characteristics of AREs (pH <4.0) with symptoms in CLD. We tested the hypothesis that in infants with CLD, AREs into the pharynx are associated with increased symptom occurrence and delayed clearance.

METHODS

Nine infants born at 29.8 +/- 5.5 wk gestation (mean +/- SD, range 24.7-39.0 wk) with CLD were evaluated for GER at 49.7 +/- 8.0 wk postmenstrual age (mean +/- SD, range 39.9-67.4 wk). Esophageal manometry was first performed to determine the nares-lower esophageal sphincter (LES) distance. A pH-impedance probe was placed at 87% of the nares-LES distance, and a recording was performed for about 24 h at cribside. Symptoms (respiratory, sensory, and movement) were documented by nurses that were blinded to the pH-impedance recordings. A symptom was considered associated with an ARE if it occurred 2 min before, during, or 2 min after the ARE. The proximal extent and associated clearance mechanisms were correlated with symptom sensitivity index (SSI = number of AREs with symptoms/total AREs *100). Multiple logistic regression methods, analysis of variance (ANOVA) models, and chi(2) tests were performed. Data are described as median, mean +/- SD, or %.

RESULTS

A total of 511 AREs, based on pH-Impedance methods, were analyzed from 203 h of recordings in the nine infants. The distal esophagus was the maximal height reached in 80% of AREs (P < 0.001, compared to other esophageal segments). Overall 33% of the AREs were associated with symptoms, and an SSI of 77% was noted with high AREs into the pharynx. The average acid clearance time was prolonged with symptomatic AREs versus nonsymptomatic AREs by 3.5-fold (P < 0.001).

CONCLUSIONS

The occurrence and frequency of symptoms with AREs depend on the most proximal extent of the ARE and the acid clearance time.

Dental erosion, gastro-oesophageal reflux disease and saliva: how are they related?

AIMS

The purpose of this study was to assess the prevalence of tooth wear, symptoms of reflux and salivary parameters in a group of patients referred for investigation of gastro-oesophageal reflux disease (GORD) compared with a group of control subjects.

MATERIALS AND METHODS

Tooth wear, stimulated salivary flow rate and buffering capacity and symptoms of GORD were assessed in patients attending an Oesophageal Laboratory. Patients had manometry and 24-h pH tests, which are the gold standard for the diagnosis of GORD. Tooth wear was assessed using a modification of the Smith and Knight tooth wear index. The results were compared to those obtained from a group of controls with no symptoms of GORD.

RESULTS

Patients with symptoms of GORD and those subsequently diagnosed with GORD had higher total and palatal tooth wear (p<0.05). The buffering capacity of the stimulated saliva from the control subjects was greater than patients with symptoms of GORD (p<0.001). Patients with hoarseness had a lower salivary flow rate compared with those with no hoarseness.

CONCLUSIONS

Tooth wear involving dentine was more prevalent in patients complaining of symptoms of GORD and those diagnosed as having GORD following 24-h pH monitoring than controls. Patients had poorer salivary buffering capacity than control subjects. Patients complaining of hoarseness had lower salivary flow rate than controls.

Mechanisms of gastroesophageal reflux and gastroesophageal reflux disease

Gastroesophageal reflux is a physiological phenomenon, occurring with different severity and duration in different individuals. Reflux occurs when this normal event results in the occurrence of symptoms/signs or complications. The pathophysiology of gastroesophageal reflux is complex and diverse, since it is influenced by factors that are genetic, environmental (e.g., diet smoking), anatomic, hormonal, and neurogenic. However, many mechanisms remain incompletely understood. Future research should focus on a better understanding of the physiology of the upper and lower esophageal sphincters, and of gastric motility. The afferent and efferent neural pathways and neuropharmacologic mediators of transient lower esophageal sphincter relaxations and gastric dysmotility require further study. The role of anatomic malformations such as hiatal hernia in children has been underestimated. While therapeutic possibilities are greater in number and largely improved, the outcomes of some treatments are far from satisfactory in many cases. In addition to development of new forms of treatment, research should address better use of currently available medical and surgical treatments.

Salivary mucin: a factor in the lower prevalence of gastroesophageal reflux disease in African-Americans?

OBJECTIVES

Organic and inorganic constituents of saliva have been implicated as protective components in the esophagus, and deficiencies in one or more of these factors in different races may be an important element in the prevalence of gastroesophageal reflux disease (GERD). To determine whether there are differences in the concentration of salivary mucins between different racial groups, we measured the concentration of mucous glycoprotein MG1 and mucous glycoprotein MG2 in whole saliva of African-Americans and Caucasians.

METHODS

Whole saliva was collected from 19 African-American (four male, 15 female; mean age 34 yr, range 19-53 yr) and 25 Caucasian (11 male, 14 female; mean age 31 yr, range 20-51 yr) volunteers under masticatory stimulation (1 g Parafilm, 60 strokes/min) between 11:00 AM and 12:00 noon. Total salivary carbohydrate was measured with a periodic acid-Schiff assay and total protein by absorbance at 215 nm. Immunological reagents were employed to quantify MG2 in a combined enzyme-linked immunosorbent assay/enzyme linked lectin assay (ELISA/ELLA) and to quantify MG1 in a capture ELISA.

RESULTS

The total carbohydrate, protein, MG1 and MG2 values were 24.4 +/- 11.9, 243.5 +/- 62.7, 21.8 +/- 13.4, and 11.6 +/- 9.5 mg% for African-Americans, and the corresponding values were 23.3 +/- 9.3, 221.7 +/- 39.7, 25.7 +/- 16.2, and 10.9 +/- 8.7 mg% for Caucasians. There was no statistical difference for any of the parameters measured between the two groups. Furthermore, it was shown that no correlation existed between salivary flow rate and the concentration of carbohydrate, protein, or salivary mucins in African-Americans and in Caucasians. These results show that flow rate did not influence the measured values for salivary parameters in the two groups.

CONCLUSIONS

No differences were found in the concentration of salivary mucins MG1 and MG2 in whole saliva of African-Americans and Caucasians, and it seems unlikely that variations in mucin levels influence the prevalence of GERD in these groups.