Replacement of functional parenchymal cells by fat and connective tissue in human submandibular salivary glands: an age-related change

Parotid Gland Suspension Combined with Rhytidectomy to Recontour the Lower Face and Neck Enlargement Caused by Benign Parotid Hypertrophy

BACKGROUND

Lower face and neck aging and facial shape changes are usually caused by soft tissue descent. During lower face and neck enlargement, parotid hypertrophy is an important influence factor of morphologic changes in the periauricular regions. Most plastic surgery techniques greatly improve the shape of the lower face and neck, but ignore the manipulation of the parotid gland. We aimed to resolve the lower face and neck enlargement caused by parotid hypertrophy. Thus, we performed parotid gland suspension combined with rhytidectomy to improve the lower face and neck contour.

METHODS

This retrospective study recruited 22 patients who underwent parotid gland suspension combined with rhytidectomy from 2012 to 2020. The evaluation of patient outcomes was performed by selecting items from the FACE-Q scale. Surgical procedures involved parotid gland exposure and parotid fascia suspension.

RESULTS

Patient-perceived age appraisal indicated a younger appearance with follow-ups for approximately 3-10 year after the surgery (mean ± standard deviation - 5.53 ± 3.67). Patients had a high satisfaction level for facial appearance (67.15 ± 16.84), lower face (74.69 ± 21.22), and contour of the parotid gland areas of the neck (65.76 ± 23.62). The lower face and neck contours were narrowed and tightened. The parotid gland area showed a remarkable improvement after surgery.

CONCLUSIONS

Parotid gland suspension combined with rhytidectomy obtained an outstanding improvement. This method can achieve a better lower face and neck contour, especially in patients with benign parotid hypertrophy or lower face and neck enlargement in periauricular regions.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Autologous mesenchymal stem cells offer a new paradigm for salivary gland regeneration

Salivary gland (SG) dysfunction, due to radiotherapy, disease, or aging, is a clinical manifestation that has the potential to cause severe oral and/or systemic diseases and compromise quality of life. Currently, the standard-of-care for this condition remains palliative. A variety of approaches have been employed to restore saliva production, but they have largely failed due to damage to both secretory cells and the extracellular matrix (niche). Transplantation of allogeneic cells from healthy donors has been suggested as a potential solution, but no definitive population of SG stem cells, capable of regenerating the gland, has been identified. Alternatively, mesenchymal stem cells (MSCs) are abundant, well characterized, and during SG development/homeostasis engage in signaling crosstalk with the SG epithelium. Further, the trans-differentiation potential of these cells and their ability to regenerate SG tissues have been demonstrated. However, recent findings suggest that the "immuno-privileged" status of allogeneic adult MSCs may not reflect their status post-transplantation. In contrast, autologous MSCs can be recovered from healthy tissues and do not present a challenge to the recipient's immune system. With recent advances in our ability to expand MSCs in vitro on tissue-specific matrices, autologous MSCs may offer a new therapeutic paradigm for restoration of SG function.

Population Based Average Parotid Gland Volume and Prevalence of Incidental Tumors in T1-MRI

Representative epidemiologic data on the average volume of the parotid gland in a large population-based MRI survey is non-existent. Within the Study of Health in Pomerania (SHIP), we examined the parotid gland in 1725 non-contrast MRI-scans in T1 weighted sequence of axial layers. Thus, a reliable standard operating procedure (Intraclass Correlation Coefficient > 0.8) could be established. In this study, we found an average, single sided parotid gland volume of 27.82 cm3 (95% confidence interval (CI) 27.15 to 28.50) in male and 21.60 cm3 (95% CI 21.16 to 22.05) in female subjects. We observed positive associations for age, body mass index (BMI), as well as male sex with parotid gland size in a multivariate model. The prevalence of incidental tumors within the parotid gland regardless of dignity was 3.94% in the Northeast German population, slightly higher than assumed. Further epidemiologic investigations regarding primary salivary gland diseases are necessary.

Age-Related Changes in the Submandibular Gland: An Imaging Study of Gland Ptosis Versus Volume

BACKGROUND

Debate surrounding the morphological evolution of the submandibular gland (SMG) with aging, and the uncertain influence of patient demographics, has led to hesitancy about incorporating targeted interventions of the SMG into clinical practice.

OBJECTIVES

The aim of this study was to determine whether SMG ptosis, hypertrophy, or both is the primary etiology behind the increase in submandibular volume with age.

METHODS

MRI segmentation was used to calculate the total and inframandibular (IM) volume and height of the SMG. Adult subjects with previous MRIs of the head and neck were used for analysis. Those with pathology or artifact compromising the SMG were excluded. Subjects were divided into 4 age-defined cohorts, for clinical applicability.

RESULTS

The study included 129 patients (65 females; 64 males) with a mean age of 52.3 years (range, 20-85 years). No significant change in total SMG volume was observed between the reference group and all cohorts. The IM-SMG volume of the reference cohort was 5.77 cm3. All 3 cohorts had a greater IM-SMG volume than the reference group. The 45- to 54-year cohort had a mean volume of 6.7 cm3 (P = 0.4), the 55- to 64-year cohort, 7.5 cm3 (P = 0.01), and the ≥65-year cohort, 7.2 cm3 (P = 0.01). Male sex and overweight or obese BMI were associated with significantly larger total and IM-SMG volumes.

CONCLUSIONS

The novel finding of a significantly larger IM-SMG volume with no change in total volume provides evidence for SMG ptosis rather than hypertrophy as a significant contributor to age-related submandibular fullness. The lack of any significant difference in total volume or height with aging emphasizes the role of glandular descent.

Can ultrasound echogenicity of normal parotid and submandibular glands be used as a reference standard for normal thyroid echogenicity?

Purpose

This study aimed to determine whether the normal parotid gland (PG) and submandibular gland (SMG) can be used as reference standards for normal thyroid echogenicity.

Methods

In total, 1,302 consecutive patients with normal salivary glands were included in this study. The echogenicity of the SMG and PG was assessed during real-time ultrasound examinations, and the glands were categorized as hyperechogenic, isoechogenic, and hypoechogenic relative to the thyroid parenchyma in patients without diffuse thyroid disease (group 1, n=1,106) and with diffuse thyroid disease (group 2, n=196). The frequency of the echogenicity categories of the normal PG and SMG was assessed according to patients’ age.

Results

In group 1, the normal PG showed isoechogenicity in 94.0% and hypoechogenicity or hyperechogenicity in 6.0%, and the normal SMG showed isoechogenicity in 73.6% and hypoechogenicity in 26.4% of patients (P<0.001). There was no significant association of the frequency of isoechoic PG with age (P=0.834); however, there was a trend for an increasing frequency of isoechoic SMG with aging (22.9%-81.4%) (P<0.001). Similar findings were found in group 2 patients without decreased thyroid echogenicity.

Conclusion

The normal PG was mostly isoechoic to the normal thyroid parenchyma, whereas the normal SMG showed hypoechogenicity at various frequencies according to age. The echogenicity of the normal PG can be used as an alternative reference standard for normal thyroid echogenicity; however, the normal SMG is not suitable for a reference standard when assessing thyroid nodule echogenicity in patients who have diffuse thyroid disease with decreased parenchymal echogenicity.

Aging-associated stem/progenitor cell dysfunction in the salivary glands of mice

Although stem cell aging leads to a decline in tissue homeostasis and regenerative capacity, it remains unclear whether salivary gland stem cell function changes during this process. However, the salivary glands are gradually replaced by connective tissue during aging. Here, we show a decline in the stem cell ability of CD133-positive stem/progenitor cells in the salivary glands of aged mice. The CD133-positive cells were isolated from young, adult, and aged mice. The number of CD133-positive cells was significantly decreased in aged mice. They also showed a lower sphere formation capacity compared to young and adult mice. RNA sequencing revealed that CD133-positive cells in aged mice exhibited lower gene expression of several aging-related genes, including FoxO3a, than those in young and adult mice. Salivary gland cells infected with a recombinant lentivirus encoding the FoxO3a gene showed a reduction in oxidative stress induced by hydrogen peroxide compared with those infected with a control virus. Thus, FoxO3a may inhibit stem cell aging via oxidative stress.

The Submandibular Gland and The Aging Neck: A Longitudinal Volumetric Study

INTRODUCTION

The true effect of aging and other patient factors on submandibular gland (SMG) volume is unclear. We sought to evaluate the effects of age, body mass index (BMI), sex and race on SMG volume using computed tomography (CT) imaging.

METHODS

We conducted a retrospective longitudinal study of adult subjects with multiple CT images of the neck at least 7 years apart. Subjects with history of salivary gland pathology, neck dissection, head and neck radiation, active infection or dental artifact were excluded. Three-dimensional volumes were measured. Age, BMI, sex and race data were analyzed to track their longitudinal effect on SMG volume.

RESULTS

The study comprised 64 patients (Females n=36; Males n=28) with mean age of 47.1 and 58.5 at each respective time point (mean difference 11.4). Mean SMG volume increased from 10.1 ml to 10.5 ml (P < 0.05). Males had significantly greater SMG volume compared to females. Majority of growth occurred in the < 40 year age bracket (0.1 ml/year), more significantly in the male cohort. When controlling for aging and sex, a change in BMI was the only patient factor that predicted a change in SMG volume. An increase of 1.0 kg/m² predicted a 0.17 ml increase in gland volume. Race had no significant effect.

CONCLUSION

Our findings suggest that the majority of SMG volume change occurs in early adulthood ( < 40 years), especially in males. Among the factors we studied, a change in BMI was the only significant predictor of SMG volume change.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 . Genital Surgery.

The Aging Parotid Gland: A Longitudinal Volumetric Study and Implications for Treatment

BACKGROUND

The parotid gland accounts for significant soft tissue volume in the face and is therefore of central relevance to facial and neck rejuvenation.

OBJECTIVES

The aim of this study was to determine how parotid gland volume is predicted by age and other factors.

METHODS

We conducted a retrospective longitudinal study of patients with multiple computed tomography (CT) scans of the neck performed at least 7 years apart. Parotid gland volumes were measured and multiple linear regression analysis was performed to model the relations between age, body mass index (BMI), and parotid volume.

RESULTS

The study cohort comprised 70 patients. The mean [standard deviation] ages at initial and final imaging time points were 47.5 [12.6] and 58.8 [12.2] years, respectively, with an average of 11.3 years elapsed between CT scans. The mean parotid gland volume increased from 28.7 [10.0] to 32.2 [10.7] mL over the average 11.3-year period (P = 0.03). However, the results of the multiple linear regression analysis show that when controlling for BMI and sex, age alone does not predict parotid volume (P = 0.29). BMI was directly correlated with gland volume (P < 0.01). An increase of 1.0 kg/m2 in BMI predicted an increase in parotid volume by 1.1 mL. Male sex was also associated with significantly greater parotid volume.

CONCLUSIONS

Mean parotid volume increased over time but these gains were driven by increases in BMI and not age alone. These findings are highly relevant to the treatment of the aging face and neck.

Relationship between dry mouth and hypertension

OBJECTIVES

Salivary dysfunction, such as reduced salivary flow and an altered salivary composition, is caused by several diseases, medical conditions, and medications. The purpose of the present study was to clarify the relationship between hypertension and morphological changes in the submandibular glands.

MATERIALS AND METHODS

An epidemiological study was conducted to elucidate the relationship between hypertension and dry mouth. The effects of hypertension on morphological changes and the intima thickness of arteries in the submandibular glands were histopathologically investigated.

RESULTS

Among 1933 subjects in the epidemiological study, 155 (8.0%) had dry mouth. A multivariate analysis revealed that dry mouth correlated with age (p < 0.001), sex (p < 0.001), and hypertension (p < 0.05). No significant differences were observed in the size of the submandibular glands between patients with or without hypertension. The average area of acinar cells was smaller in patients with than in those without hypertension (0.366 ± 0.153 vs. 0.465 ± 0.178, p < 0.05). The arteriosclerotic index was significantly higher in patients with than in those without hypertension (0.304 ± 0.034 vs 0.475 ± 0.053, p < 0.05).

CONCLUSIONS

Hypertension may contribute to the degeneration of the submandibular glands by decreasing the number of acinar cells and promoting fatty infiltration and stenosis of the arteries.

CLINICAL RELEVANCE

There may be a correlation between hypertension and the degeneration of the submandibular glands by decreasing the number of acinar cells and promoting fatty infiltration and stenosis of the arteries.

Salivary side effects after radioiodine treatment for differentiated papillary thyroid carcinoma: Long-term study

BACKGROUND

Although many studies focus on short-term side effects of radioiodine therapy, almost none studied long-term side effects. We assessed radioiodine long-term salivary side effects after radioiodine treatment for differentiated papillary thyroid carcinoma and compared it to short-term morbidity within the same population.

METHODS

A standardized self-administrated questionnaire was submitted in 2019 by patients treated with radioiodine between January 2011 and December 2012. These patients had already answered the same questionnaire 6 years before.

RESULTS

Our study showed a significant reduction for salivary side effects: discomfort in submandibular or parotid area, swelling, pain, a bad or salty taste in the mouth, allowing to get back to a "normal" diet.

CONCLUSIONS

Our study suggests that a significant rate of patients will recover from I¹³¹ therapy salivary side effects. As almost 30% of these remissions happened during our late stage follow-up, we highlight the necessity of a long-term follow-up in these patients.

Ultrasonographic and elastographic biometry in adult major salivary glands: a preliminary case-control report

Specifications about the size and stiffness of healthy salivary glands with ultrasound (US) are not available for Asian people. Using a Toshiba Apolio 500 US platform, we determined the size (including anterior-posterior median length, median paramandibular depth dimension, and cranio-caudal height) and hardness of 100 healthy submandibular and parotid glands in volunteers without a history of disease affecting the salivary glands or post-radiation, and compared the dimensions to those of 36 parotid glands and 37 submandibular glands in post-irradiated patients. The dimensions of the parotid and submandibular glands were significantly correlated with body weight. However, the dimension of the parotid glands was not significantly correlated with that of patients with prior radiation; the shear wave velocity (SWV) significantly increased (1.99 m/s versus 2.43 m/s, p-value < 0.01). The dimension of the submandibular glands was significantly correlated with prior radiation, where the SWV also significantly increased (2.32 m/s versus 2.50 m/s, p-values < 0.01). We find that US is a useful tool for assessment of the reference dimensions and hardness of major salivary glands that may be altered by irradiation.

Salivary secretion in health and disease

Saliva is a complex fluid produced by 3 pairs of major salivary glands and by hundreds of minor salivary glands. It comprises a large variety of constituents and physicochemical properties, which are important for the maintenance of oral health. Saliva not only protects the teeth and the oropharyngeal mucosa, it also facilitates articulation of speech, and is imperative for mastication and swallowing. Furthermore, saliva plays an important role in maintaining a balanced microbiota. Thus, the multiple functions provided by saliva are essential for proper protection and functioning of the body as a whole and for the general health. A large number of diseases and medications can affect salivary secretion through different mechanisms, leading to salivary gland dysfunction and associated oral problems, including xerostomia, dental caries and fungal infections. The first part of this review article provides an updated insight into our understanding of salivary gland structure, the neural regulation of salivary gland secretion, the mechanisms underlying the formation of saliva, the various functions of saliva and factors that influence salivary secretion under normal physiological conditions. The second part focuses on how various diseases and medical treatment including commonly prescribed medications and cancer therapies can affect salivary gland structure and function. We also provide a brief insight into how to diagnose salivary gland dysfunction.

Relationship between hyposalivation and oxidative stress in aging mice

The increase in oxidative stress that accompanies aging has been implicated in the abnormal advance of aging and in the onset of various systemic diseases. However, the details of what effects the increase in oxidative stress that accompanies aging has on saliva secretion are not known. In this study, naturally aging mice were used to examine the stimulated whole saliva flow rate, saliva and serum oxidative stress, antioxidant level, submandibular gland H-E staining, and immunofluorescence staining to investigate the effect of aging on the volume of saliva secretion and the relationship with oxidative stress, as well as the effect of aging on the structure of salivary gland tissue. The stimulated whole saliva flow rate decreased significantly with age. Also, oxidative stress increased significantly with age. Antioxidant levels, however, decreased significantly with age. Structural changes of the submandibular gland accompanying aging included atrophy of parenchyma cells and fatty degeneration and fibrosis of stroma, and the submandibular gland weight ratio decreased. These results suggest that oxidative stress increases with age, not just systemically but also locally in the submandibular gland, and that oxidative stress causes changes in the structure of the salivary gland and is involved in hyposalivation.

Altered autophagy and sympathetic innervation in salivary glands from high-fat diet mice

OBJECTIVE

to investigate the effects of a high fat diet (HFD) on salivary glands in vivo, in a mouse model. In particular, whether it will induce the appearance of fat cells in salivary glands, alterations related to autophagy, mTOR pathway and sympathetic innervation.

DESIGN

27 adult female ICR mice were separated in six groups. Three groups fed with (HFD) containing 55% fat, for one, two and three month and another three groups fed with normal diet (2.7% of fat), for the same time periods. The submandibular glands and liver were dissected and part homogenized for protein analyses and part fixed in formalin for histological analyses.

RESULTS

After three months the HFD fed mice total body weight fold change increased compared to controls. The Oil Red O staining showed no fat cells deposit in salivary gland however a large increase was observed in liver after three months of HFD. Adiponectin levels were significantly decreased in the HFD group after three months. The group fed with HFD for three months showed increased conversion of the LC3 autophagy marker in salivary gland. mTOR showed no activation regarding the time point studied. Tyrosine hydroxylase significantly decreased after two and three month of HFD.

CONCLUSION

HFD caused several changes after three months however the earliest change was noticed after two months regarding sympathetic innervation. This suggests neural alteration may drive other diet induced changes in salivary glands. These early changes may be the starting point for longer term alterations of salivary glands with alterations in diet.

Phenotype and cell proliferation activity of duct-like structures in human sublingual glands: a histological and immunohistochemical study

There are several age-related microscopic changes in the salivary glands, including the increase in the number of duct-like structures (DLS). However, the true origin and the phenotype of the DLS are not known.

Morphology and morphometry of the human sublingual glands in mouth floor enlargements of edentulous patients

Asymptomatic mouth floor enlargements may be observed in edentulous patients. These masses, which protrude from the mouth floor, may complicate the fitting of dentures and require surgery. Whether this "entity" may be considered an anatomical variation of the mouth floor or represent specific alterations in the sublingual gland is not known.

Analysis of age-related changes in the functional morphologies of salivary glands in mice

BACKGROUND AND OBJECTIVES

Salivary glands in the elderly commonly exhibit salivary dysfunction resulting dry mouth, poor oral hygiene, and dental caries. However, in vivo changes of salivary glands during aging have not been well documented in the literature. This study was undertaken to determine age-related morphometric and functional changes of salivary glands using an aging mouse model.

METHODS

Male C57BL/6 mice were divided into three groups, group A (10 weeks old; n=10), group B (30 weeks old; n=10), and group C (90 weeks old; n=10). Body weights, salivary gland weights, salivary flow rates, and salivary lag times were measured and compared. Histomorphometric examinations and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays were performed. In addition, changes in salivary uptake and excretion were observed by single-photon emission computed tomography (SPECT).

RESULTS

Body and gland weights increased with age. Gland weight was significantly higher in group B than in groups A and C. Salivary lag time was significantly greater in group C than in groups A and B, and salivary flow rate was significantly greater in group B than in groups A and C. Histologic evaluations exhibited acinar cell atrophy, cytoplasmic vacuolization, lymphocyte infiltration, small mucin component and more periductal fibrosis in salivary glands of group C. TUNEL assays revealed that apoptotic salivary epithelial cells were significantly more numerous in group C than in groups A and B. (99m)Tc-pertechnetate excretion rate was significantly lower in group C than in groups A and B in SPECT.

CONCLUSION

Various morphometric and histopathological changes were observed in the salivary glands of aging mouse as well as relevant functional alterations, such as, decreased saliva production and excretion. Increased number of apoptotic salivary epithelial cells may contribute to the observed functional deterioration.

Assessment of age-related morphological and functional changes of selected structures of the head and neck by computed tomography, magnetic resonance imaging, and positron emission tomography

The head and neck is a complex anatomical region that can be evaluated using many imaging modalities. It is important to discern normal structures from ones that are affected by disease and to study how these structures change in their morphological and functional properties with aging. Therefore, using magnetic resonance imaging (MRI), we retrospectively evaluated volumes of the parotid glands, submandibular glands, thyroid gland, tongue, soft palate, and lingual tonsils in 64 subjects ages 13 to 81 years. Volume, attenuation (HU), and metabolic activity (maximum SUV) of the parotid, submandibular, and thyroid glands were assessed retrospectively using positron emission tomography/computed tomography (PET/CT) imaging in 35 subjects ages 10 to 76 years. Metabolic activity (maximum SUV) of the parotid, submandibular, and sublingual glands; tongue; adenoids; and tonsils (lingual and palatine) were evaluated retrospectively using PET imaging in 15 subjects ages 6 to 20 years. Metabolic volumetric products of the parotid, submandibular, and thyroid gland were calculated and analyzed with increasing age in subjects who underwent PET/CT imaging. Structures that exhibited statistically significant changes (P < 0.05) with increasing age included the submandibular glands, thyroid gland, soft palate, and adenoids. The CT volume of the submandibular glands increased with age, and the attenuation decreased with age with statistical significance. The thyroid gland volume, as measured using MRI, showed a statistically significant decrease with aging. The volume of the soft palate and lingual tonsils, as measured by MRI, exhibited a statistically significant decrease in volume with aging. The maximum SUV of the adenoids demonstrated a statistically significant decrease with aging. In conclusion, CT, MRI, and PET may be used to quantitatively and qualitatively assess structures of the head and neck and are useful in the assessment of structural and functional changes of these structures with aging.

Quantitative age-related differences in human sublingual gland

OBJECTIVE

To quantify morphological age- and gender-related differences in human sublingual glands (SLG).

DESIGN

Ninety right human SLG from necropsies were distributed by gender and age groups. Individuals with ages ranging from 7 months to 92 years were divided into Groups I (0-30 years), II (31-60 years) and III (61-92 years). The glandular volume of each SLG was calculated. The morphometric quantifications of the volume density and total volume of acini, ducts, stroma, adipose tissue and septa were realized under light microscopy using a Zeiss II integration grid with 100 points symmetrically distributed.

RESULTS

The glandular volume decreased, on average, 33.78% across the groups. The volume density (V(V)) of acini reduced 60.54% and of septa 34.82%, being replaced partly by an increase of 58.82%, 551.22% and 2,783.33% in the volume density of ducts, stroma and adipose tissue, respectively. In absolute terms, with aging, the total volume (V(T)) of the acini decreased by 54.04% and by 34.84% in the septa. In contrast, the total volume of ducts, stroma and adipose tissue showed increases of 62.53%, 363.25% and 2,308.64%, respectively. Both the V(V) and the V(T) of acini, ducts, stroma and adipose tissue and the V(V) of septa were statistically different with age. No significant difference was observed between genders.

CONCLUSION

The decrease of parenchyma accompanied by an increase of stroma observed here in SLG is a common feature of aging in human salivary glands.

Mouth floor enlargements related to the sublingual glands in edentulous or partially edentulous patients: a microscopic study

Mouth floor enlargements (MFE) are observed in edentulous and partially edentulous patients, impairing denture fitting, and have recently been described in the literature as hyperplasias of the sublingual glands.

OBJECTIVE

This study aims at describing the microscopic aspects of MFE that contribute to their final diagnosis.

METHODS

Twenty-four specimens were surgically removed from the enlarged mouth floor of 19 patients (15 females and 4 males). Patient age ranged from 48 to 74 years, with a mean of 57 years. The main surgical indication was to permit or improve the fitting of dentures. Six patients were completely edentulous and 13 were partially edentulous. The material was processed for microscopic examination and stained with hematoxylin-eosin, Mallory's trichrome and periodic-acid Schiff (PAS).

RESULTS AND CONCLUSIONS

The epithelium of the mouth floor was normal in 17 cases, hyperplastic in 4 and atrophic in 3. Six of the 24 sublingual glands removed were microscopically normal, while the other specimens presented acinar atrophy with hyperplasia of duct-like structures. Interstitial fibrosis was observed in 18 cases and was accompanied by adipose tissue infiltration in 15. Decreased lymphoid tissue was observed in 16 samples and oncocytosis was present in 5 cases. We suggest that MFE in edentulous or partially edentulous patients should be considered as an entity for the text books.

The pH change after HCl titration into resting and stimulated saliva for a buffering capacity test

BACKGROUND

Saliva collection can provide clinical information about individual patients. However, a correlation between ranking buffering capacity using resting and stimulated saliva is still unknown. The aim of this study was to evaluate the pH change after HCl titration into resting and stimulated saliva for a salivary buffering capacity test.

METHODS

Resting and stimulated saliva (by chewing paraffin wax) were collected from 80 patients. After the pH of both saliva samples was measured using a hand-held pH meter, the saliva samples were titrated with 0.1N HCl to evaluate the buffering capacity. Correlations of ranking buffering capacity (high, medium, low) between stimulated saliva and resting saliva with 30 microL HCl titration and between stimulated saliva and resting saliva with 40 microL HCl titration were statistically analysed by Spearman Rank Correlation Test (p < 0.05).

RESULTS

At 50 microL HCl titration, stimulated saliva buffering capacities were ranked into high (above pH 5.5), medium (pH from 5.5 to 4.5) and low (below pH 4.5). At 30-40 microL HCl titration, the resting saliva buffering capacities were ranked into the same categories. Spearman Rank Correlation indicated significant positive coefficients for the stimulated saliva and resting saliva buffering capacity at 30 microL titration and the stimulated saliva and resting saliva at 40 microL titration.

CONCLUSION

Stimulated saliva is more resistant to variation in pH change during HCI titration than resting saliva. Stimulated saliva sampling is a good method to determine buffering capacity during a comprehensive oral health assessment.

Principles of geriatric dentistry and their application to the older adult with a physical disability

The older adult living with a physical disability faces many daily challenges. Limited hand function or impaired cognition often has profound effects on activities of daily life including oral hygiene. This article explores age-related changed in dentition and common causes of pathology of the oral cavity with special emphasis in populations with impaired hand function or cognition. This article will also assist the treating physician as it relates to oral diagnosis and patient management.

Age-related changes in human sublingual glands: a post mortem study

OBJECTIVES

To analyse age- and gender-related microscopic changes in sublingual glands obtained from human cadavers.

STUDY DESIGN

One hundred eighty six human sublingual glands were obtained from 93 autopsies. Approximately five individuals of each gender per decade of life were allocated to three age groups: group I (0-30 years, n=26); group II (31-60 years, n=32) and group III (61-90 years, n=35). The specimens were fixed in 10% formalin and submitted to routine histological processing, and sections were stained with hematoxylin and eosin.

RESULTS

Significant differences with increasing age were observed for the following microscopic aspects: acinar atrophy (r=0.26, p=0.0115); replacement of parenchyma by fibrous tissue (r=0.79, p<0.0001) and/or adipose tissue (r=0.63, p<0.0001); oncocytosis (r=0.61, p<0.0001); duct-like structures (chi(2)=14.68, p=0.0006) and congested blood vessels (chi(2)=7.18, p=0.0276). The mononuclear infiltrate changed from focal to diffuse with age (H=8.47, p=0.0144). No significant differences were observed between genders.

CONCLUSIONS

The aging process starts with acinar atrophy, followed by the presence of duct-like structures and ends with the replacement of the parenchyma by fibrous and/or adipose tissue. The mononuclear infiltrate changes from focal to diffuse. No difference in the aging of the sublingual glands is observed between men and women.

Parotid gland secretion of the aging rat

Saliva secretion stimulated by alpha adrenergic beta adrenergic and muscarinic cholinergic neurotransmitters was evaluated in young adult and old rats. Parotid saliva was collected following methoxamin (METH) (6 mg/kg), isoproterenal (ISO) (30 mg/kg), or pilocarpin (PILO) (7.5 mg/kg) as secretory stimuli. The flow rate and the concentrations of protein, Na+ and K+ were measured. Saliva flow rate was 40%-50% lower (P < 0.01) in old rats following METH and PILO, but there was no difference following ISO stimulation. Saliva of old rats stimulated by METH or PILO contained about 30%-40% more (P < 0.01) protein. Comparable protein levels were in saliva stimulated by ISO. No changes were found in Na+ and K+ concentrations in all saliva samples. These results suggest that the age-related alteration in flow rate is not a general phenomenon, but rather specific and limited to the high flow rate stimulants (alpha-adrenergic and muscarinic-cholinergic). Transport alteration from the circulatory system into the parotid gland may be the underlying mechanism.

Histopathological investigation of salivary glands in the asymptomatic elderly

The significance of labial gland biopsies (LGBs) in the diagnosis of Sjögren's syndrome (SS) in the elderly has been a controversial subject since it is complicated by age-related histopathological changes. In an attempt to clarify the appropriateness of LGBs in present diagnosis criteria, we evaluated the specificity of LGBs using autopsied tissues. This was done by taking labial, sublingual and submandibular salivary glands from 53 autopsy subjects (24 males and 29 females) with an average age of 84 years, and testing them histopathologically with reference to a previously reported grading system. None had any sicca symptoms (oral dryness or dry eye). In subjects up to 75 years old, acinar atrophy was more frequent in labial glands than in the two major salivary glands (P=0.0098 for sublingual and P=0.0009 for submandibular glands). Also, while there were significant differences in frequency of such atrophy between the sublingual and submandibular salivary glands of subjects younger and older than 75, the labial glands showed no such variation. Taking grade 3 (focus score of 1) as the diagnosis criterion, two subjects were determined to have SS in which case the specificity was 95%. Using contemporaneous serological test results for anti-SSA/Ro antibodies as a diagnostic criterion raised specificity to 98%. For both major and minor glands, these appeared to be no relationship between degree of lymphocytic infiltration and age. Our results thus suggest that it is appropriate to adopt a focus score of 1 as a diagnostic criterion for SS in the elderly, and that serological test results can improve specificity.

The relationship between salivary secretion rate and masticatory efficiency

In order to elucidate the relationship between the salivary secretion rate and masticatory efficiency, experimental hypo- and hyper-salivation were produced by the administration of atropine sulphate presenting an anticholinergic effect and pilocarpine hydrochloride having a muscarine effect orally in 10 healthy fully dentates. To confirm the pharmaceutical effect of these drugs, the unstimulated whole salivary secretion rate during 10 min, and masticatory efficiency using the sieve method were measured before and after medication. The unstimulated whole salivary secretion rate during 10 min decreased significantly by the administration of atropine sulphate (P < 0.05), and increased significantly by pilocarpine hydrochloride (P < 0.01). The masticatory efficiency after atropine sulphate medication was significantly lower than that before (P < 0.01). The increase in salivary secretion by pilocarpine hydrochloride did not lead to a higher masticatory efficiency. The evidence supports the understanding that saliva plays an important role in masticatory function.

Quantitative analysis of normal major salivary glands using computed tomography

OBJECTIVES

We sought to calculate the size and the computed tomography (CT) number of normal parotid and submandibular glands and to evaluate their relationship with respect to sex, age, and obesity in the Korean population.

STUDY DESIGN

The authors investigated the axial CT images of 42 healthy volunteers. The maximum cross-sectional area (MCSA) was used as an indicator of the size of the gland. Three regions of interest on axial scans were selected to calculate the mean CT number.

RESULTS

There was a significant decrease in the mean MCSA of the submandibular gland and the CT number of both glands with age. The MCSA of the submandibular gland in males was larger than that in females. There was a close correlation between the parotid and the submandibular glands with respect to the CT number, as well as between the left and right glands with respect to the MCSA and the CT number. The body mass index was positively correlated with the MCSA of the parotid gland, whereas the body mass indexes and the CT numbers of both glands were negatively correlated.

CONCLUSIONS

Both age and obesity are closely correlated with the size and the CT number of the major salivary glands. Moreover, the correlation between the CT numbers of the parotid and the submandibular glands may be used for diagnostic purposes.

Xerostomia and hyposalivation

Dry mouth must not be considered a trivial problem in the population, since it constitutes a phenomenon with many aspects relative to oral function as well as quality of life. Up until today, no global consensus has been reached with regard to the terminology of dry mouth, creating a substantial problem for research, education, diagnosis, and therapy. In this report, salivary gland hypofunction has been selected as the overarching term for subjective symptoms and objective signs of dry mouth. Its different aspects--xerostomia, hyposalivation, and altered saliva composition--are reviewed with respect to prevalence, diagnosis, and etiology. It is concluded that these aspects of salivary gland hypofunction are separate entities, which in many respects are interrelated, constituting not merely a dental but also a medical and social concern.

The effect of ageing on parenchymal cell populations in adult female mouse submandibular gland

The submandibular gland shows an array of responses that accompany ageing, which are usually modest. However, the submandibular acinar-cell mucin shows a substantial decline in total amount per gland. In the submandibular gland, there is also a loss of secretory parenchyma. A number of factors that could influence either parenchymal loss or a change in its cellular composition were examined in three ages of adult female mice. The goal was to see if there are ageing-related cellular changes that might have an effect on mucin production or secretion. The factors examined included DNA, protein, rates of cell division and apoptosis, cell volume and cellular composition of the parenchymal population. The parenchymal cell composition showed significant differences during ageing, with a substantial decrease in the percentage of acinar cells and increases in the percentage of both types of ductal cell components. This decline in the proportion of acinar cells in the parenchyma also reflected an overall reduction in the total number of acinar cells in the gland. Thus, the change in proportions of cells may potentially be a direct cause of the ageing-related decline in the submandibular acinar-cell mucin. The alteration in cellular composition was not attributable to changes in the cell-division indices; however, there was an increased rate of apoptosis for acinar cells that was significantly different between 3 and 28 months. The apoptotic rate doubled for acinar cells but showed no significant change in ductal cells. This selective change in the rate of apoptosis with ageing suggests that it is one of the main reasons for the decline in the proportion of acinar cells in the submandibular gland.

Saliva in health and disease: an appraisal and update

Saliva plays an important role in oral health monitoring, regulating and maintaining the integrity of the oral hard tissues and some soft tissues. This paper reviews the role of saliva, the prevalence of oral dryness and the consequent importance of salivary flow as well as the relationship between xerostomia and salivary gland hypofunction amongst the causes of oral dryness. Other aspects of oral conditions associated with saliva are also reviewed including Sjögren's Syndrome and oesophageal function. Finally, knowledge, and the current use of salivary tests and the utilisation of saliva as a diagnostic fluid are surveyed.

Salivary mucin as related to oral Streptococcus mutans in elderly people

MG1 (MUC5b and MUC4) and MG2 (MUC7), predominant mucins in human whole saliva, provide lubrication and antimicrobial protection for oral tissues. This study examines potential relationships between Streptococcus mutans titers in the oral cavity and the following: mucin concentrations; unstimulated and stimulated whole saliva flow rates; decayed, missing, and filled tooth surfaces; and age of 24 elderly patients. S. mutans titers were determined using Denticult SM. Mucin concentrations were determined using Stains-all, sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Logistic regression was used to identify potential relationships between the above variables. S. mutans classification served as the dependent variable. The remaining variables were possible predictor variables. The best model for predicting S. mutans category contained log MG2 as a predictor variable for all of its parameter estimates. No other set of parameter estimates were statistically significant. These results suggest that elevated S. mutans titers are significantly associated with diminished concentrations of MG2 in unstimulated whole saliva, as quantified in mucin-dye binding units.

Digestive System 1

This chapter deals with the digestive system. The major and minor salivary glands and their secretions also represent and integral part of the protective mechanism of the oral cavity, and derangement of saliva production may lead to loss of integrity of the oral mucosa. Drug-induced abnormalities of taste sensation are also well-described phenomena occurring in man although human studies are necessary for the detection of these effects. Inflammation of the oral cavity may involve the buccal mucosa, the gingiva (gingivitis), the tongue (glossitis), and the peridontal tissues (peridontitis). Therapeutic agents can induce inflammatory lesions in the tongue. Moreover, a protective layer of mucus, a visco-elastic material containing high molecular weight glycoproteins produced by the major and minor salivary glands, covers the stratified squamous mucosa of the oral cavity. Salivary secretions also possess digestive enzyme activity although in herbivores and carnivores, it is usually low in contrast to high digestive enzyme activity in omnivorous species.

Age-related changes in cellular activity in human submandibular glands as evaluated by argyrophilic nucleolar organizer regions

OBJECTIVE

To examine the age-related changes in cellular activity of epithelial components of human submandibular glands, evaluated on the basis of argyrophilic nucleolar organizer regions (AgNORs).

DESIGN

Epithelial components of human submandibular glands were divided into serous acinar cells, mucous acinar cells, intercalated duct cells, striated duct cells, and interlobular duct cells. The mean AgNOR number of each cell type was compared among six age groups.

SETTING

The study was conducted at the Department of Oral Pathology, Tohoku University School of Dentistry, Japan.

SUBJECTS

Necropsy specimens from 66 males and 57 females 1 to 97 years old.

RESULTS

In all cell types except for intercalated duct cells, the mean AgNOR number was lowest in the 0-14 year-old group and highest in the 15-29 year-old group. The value then gradually decreased with advancing age and ultimately reached a similar level to that in the 0-14 year-old group. In intercalated duct cells, the mean AgNOR number did not differ significantly between any age group. There were no significant sex-related differences.

CONCLUSIONS

The cellular activity of almost all components of human submandibular glands rises in adolescence and young adulthood and then decreases with aging. These results suggest that intercalated duct cells are capable of not only proliferation but also division into other components; these cells may thus compensate for the reduced activity of other components in elderly subjects.

Lipomatous pleomorphic adenoma of the parotid gland. Classification of lipomatous tissue in salivary glands

Lipomatous pleomorphic adenoma is an unusual subtype with a lipomatous stromal component of more than 90% of the tumour tissue. This special type of pleomorphic adenoma must be distinguished from other types of lipomatous tumours or non-tumourous lipomatosis of the salivary glands. Until now only two cases of lipomatous pleomorphic adenoma have been reported in the literature. We report of a 36-year old woman who developed a well circumscribed nodule measuring 3.5 x 2.5 x 2 cm in the right parotid gland. The cut surface was grey-yellowish. Histologically, more than 90% of the tumour tissue was fatty tissue with univacuolar adipocytes. The pleomorphic epithelial elements were duct-like cells forming small lumina and spindle-shaped myoepithelial cell with surrounding mucoid stroma. Components of pleomorphic adenoma were intermingled with mature adipose tissue which was more concentrated in the central portion of the adenoma. Some compressed epithelial cords in the adipose tissue formed a septa-like pattern. The differential diagnosis to other lipomatous tumours (lipoadenoma, lipoma) and to non-tumourous interstitial lipomatosis as well as the possible pathogenesis as metaplastic change or epithelial-mesenchymal transdifferentiation are discussed.

Saliva mediated adherence, aggregation and prevalence in dental plaque of Streptococcus mutans, Streptococcus sanguis and Actinomyces spp, in young and elderly humans

Salivary components in the pellicle mediate bacterial adherence to the tooth. Such components may also aggregate bacteria in saliva and prevent them becoming established in dental plaque. In the present study, the adherence and aggregation of Streptococcus mutans strain Ingbritt, S. sanguis strain 10556 and Actinomyces viscosus-strain 19246 mediated by parotid and whole saliva from groups of young and elderly people were examined. Significant differences were found between test strains, salivary secretions and age groups. S. sanguis 10556 and A. viscosus 19246 generally adhered more strongly than S. mutans Ingbritt, which adhered better to pellicles from parotid saliva than from whole saliva Strain 19246 bound in higher numbers to parotid saliva pellicles from elderly compared to young individuals. Strain 10556 adhered better to whole saliva than parotid saliva pellicles, and the difference was significant among the young individuals, indicating reduced adherence ability in elderly whole saliva. The streptococci were aggregated by parotid and whole saliva, and S. sanguis aggregation was less with whole saliva from the elderly than from the young participants. Besides a correlation between whole saliva aggregation of S. mutans and proportions of bacteria in plaque, no correlations were found for the individual binding properties of saliva and prevalence of bacteria in vivo. However, the level of saliva-mediated adherence in vitro was in the following order: S. mutans. Actinomyces S sanguis, which corresponded to their isolation frequency in plaque. These findings emphasize the importance of initial adherence to salivary receptors in bacterial colonization on teeth. Further studies are needed to reveal if individual patterns in the in vitro binding characteristics of saliva lead to variation of colonization in vivo.

Quantitative analysis of the submandibular gland using computed tomography

OBJECTIVE

To evaluate the normal variation in size of the submandibular gland from computed tomographic (CT) scans.

MATERIALS AND METHODS

CT was performed parallel to the Frankfurt horizontal (FH) and mandibular (MP) planes in 130 subjects (64 men and 66 women) with healthy submandibular glands, six patients with sialoadenitis and four with masseteric hypertrophy.

RESULTS

The mean (s.d.) maximum cross-sectional area (MCSA) of the submandibular glands for FH was 324 (89) mm2 and for MP 364(101) mm2. There was a high correlation between individuals' right and left glands. There was no significant difference in the mean MCSA between the right and left, which varied by less than 10%. The mean (s.d.) volume of the gland was 8072 (2574) mm3. With a high correlation with mean MCSA in both scanning planes, the mean MCSA may be an indicator of the volume of the gland. MCSA increased significantly with body height, weight and body mass index, but decreased with age. The MCSA of the affected side in patients with sialoadenitis and masseteric hypertrophy was larger than both that of the normal side and the predicted values.

CONCLUSION

MCSA is a useful indicator of gland volume, and differences of greater than 10% between the two sides may be used in the diagnosis of submandibular gland disease.

Cell deletion by apoptosis during regression of rat parotid sialadenosis

Enlargement of the rat parotid salivary glands was induced by repeated administration of isoproterenol. Mean wet weights of the treated glands increased steadily to 240% of control values. Following withdrawal of the drug, quantitative histological techniques were used to investigate the balance between hypertrophy, hyperplasia and apoptosis. The volume occupied by acinar cells relative to the total gland volume together with cytoplasmic magnitude of nuclear area ratios as measures of hypertrophy increased during the early experimental period. Similarly, serous acinar cell mitotic counts increased, indicating that hyperplasia had occurred. Apoptosis was demonstrated at light microscopical level to be the main mechanism for cell deletion as the glands returned to normal size and weight. The results indicate that hypertrophy and hyperplasia of serous acinar cells contribute to isoproterenol-induced sialadenosis. The experimental animal model demonstrates that these proliferative changes are completed by 48 h and thereafter are balanced by apoptosis as the glands recover their normal size and weight.

Histopathologic study of human lacrimal gland. Statistical analysis with special reference to aging

PURPOSE

Histopathologic changes in human lacrimal gland were investigated, and the relation between histopathologic parameters and patient age and sex, as well as the histopathologic differences between palpebral and orbital lobes of the lacrimal gland were analyzed.

METHODS

Samples of the main human lacrimal gland that included the palpebral lobes and orbital lobes were taken in 80 autopsies. A statistical analysis was made based on light microscope observations with the following histopathologic changes as parameters: (1) fibrosis (focal, lobular, and diffuse); (2) acinar atrophy (focal, lobular, and diffuse); (3) periductal fibrosis; (4) interlobular ductal dilatation; (5) interlobular ductal proliferation; (6) lymphocytic foci; (7) periductal lymphocytic infiltration; and (8) fatty infiltration.

RESULTS

The incidences of these parameters in the palpebral and orbital lobes ranged from 3.8% to 35.0%. Lobular fibrosis, lobular atrophy, diffuse fibrosis, diffuse atrophy, periductal fibrosis, lymphocytic infiltration, and fatty infiltration were more frequent in the orbital lobes with statistical significance, whereas interlobular ductal dilatation was more frequent in the palpebral lobes. There were statistically significant correlations between age and diffuse fibrosis, diffuse atrophy, and periductal fibrosis in the orbital lobes of women, and periductal fibrosis in the palpebral lobes of men. Diffuse fibrosis and diffuse atrophy in the orbital lobes were observed more frequently in elderly women than in elderly men.

CONCLUSIONS

Various histopathologic changes were observed in the human lacrimal gland. Diffuse fibrosis, diffuse atrophy, and periductal fibrosis predominantly found in elderly women suggested a relation with keratoconjunctivitis sicca in postmenopausal women. The authors speculate the periductal fibrosis is related to the decrease in tear fluid outflow with age and that interlobular ductal dilatation in the palpebral lobes may be caused by stenosis of the excretory duct in the fornix of conjunctiva. Ductal pathologic changes may be important in lacrimal gland dysfunction.

Structural and functional changes in salivary glands during aging

Various salivary glands in senescent humans and other animals have been examined extensively to characterize the structural and functional changes that occur during aging. Although a wide range of different structural changes, involving both the parenchymal and stromal tissues, have been described, it is unclear how any of these changes affects the function of the salivary glands. One major change in structure is the reduction in the volume of acini with a concomitant increase in the ductal volume. Despite this loss of functional acini, the salivary output and the contents seem to be unaltered, or minimally altered, due to aging. One consistent change observed in many salivary glands of aged animals is the decline in the rate of synthesis of proteins and their messenger RNA (mRNA). However, the salivary acinar cells from aged animals can synthesize secretory proteins at an elevated rate just as effectively as those from their younger counterparts in response to external stimuli, which are known to enhance the rate of protein synthesis. Thus, it appears that the salivary acinar cells, which remain structurally intact during aging, seem to retain their functional efficiency. Furthermore, these acinar cells, although reduced in number, are sufficient in quantity to carry out most of the salivary gland functions.

Effect of age on immunoglobulin content and volume of human labial gland saliva

Stimulated lower labial (LLGF) and parotid salivary volumes and IgG, IgA, and IgM concentrations were measured in 264 subjects whose ages ranged from 17 to 76 years. A significant (p < 0.001) age-related decline in LLGF output was observed for subjects over this age range. Sixty-three percent of the subjects in the 18-20-year-old group (n = 46) secreted at least 10 microL of labial saliva in a 7-10-minute period, while approximately 70% of the subjects in the two oldest groups (61-70 and 71-76 years old) secreted less than 1 microL of LLGF during this time period (n = 64). No significant gender-based differences occurred in the volumes of labial saliva secreted. Stimulated parotid salivary flow showed no age-related trend in these subjects. Lower labial gland salivary IgA concentrations in an older population (mean age +/- SD = 55.6 yr +/- 1.3) were significantly lower (p < 0.025) than IgA concentrations in a younger population (20.7 yr +/- 0.8), when IgA was expressed as microgram/mL LLGF collected. Immunoglobulin A concentrations in parotid saliva and IgG and IgM concentrations in labial and parotid saliva were not significantly different when the two age populations were compared. These data suggest that the physiological and immunological potential of labial gland saliva may decrease with age.

Salivary gland function and aging: a model for studying the interaction of aging and systemic disease

This review describes an approach to examining the interaction of aging and systemic disease on a key aspect of oral physiology, salivation. The approach requires several steps: defining general health, and a specific physiological function, at different ages; defining a disease of interest and the influence of the disease on the specific physiological function; and determining if the disease can affect performance of the physiological function with increased age.

Oral defense factors in the elderly

Continuously increasing proportion of elderly people in the human population creates new challenges for the dental care. Because the microbial etiology of the most common oral diseases, dental caries, endodontal and periodontal diseases, is not substantially different in different age groups, the altered host response during aging may modify the progression of these diseases. Most prevalent and severe change in the oral defense is hyposalivation or xerostomia but aging as such does not seem to reduce neither parotid nor whole salivary flow rate. However, submandibular and minor salivary glands produce less saliva at old age which may be the reason for the frequently reported symptoms of oral dryness even if the stimulated flow rate is normal. Concomitantly to the changes in the flow rate the daily output of many saliva-mediated defense factors declines but age-related impairment has been described only for specific IgA response to external antigens, for salivary opsonic activity, and for T-lymphocyte function. The non-immunoglobulin defense factors seem to act with full capacity over the entire life-span. Therefore, elderly people with normal salivary flow rate possess no special risk group for the development of oral diseases.

Comparison of whole saliva flow rates and mucin concentrations in healthy Caucasian young and aged adults

Unstimulated and chewing-stimulated whole saliva samples were obtained from 42 healthy Caucasians; 21 were between 18 and 35 years of age, and 21 between 65 and 83 years of age. The unstimulated salivary flow rate was significantly lower in the aged group, but the stimulated flow rate was significantly higher in the aged than in the young group. Both groups showed significantly increased flow during salivary stimulation. MG1 and MG2 concentrations in unstimulated and stimulated saliva samples were significantly lower in the aged group. There were no significant correlations between salivary flow rates and MG1 and MG2 concentrations.

Increased mucin levels in submandibular saliva from mice following repeated isoproterenol treatment

Mucin decreases with age in the submandibular glands of mice and can be restored by chronic administration of isoproterenol. Mice were given repeated injections of isoproterenol to determine if the increase of mucin in the submandibular gland leads to elevated levels of mucin in the submandibular saliva. Mucin was significantly elevated in both the gland and the saliva after isoproterenol. Gland contents of mucin and the concentration of mucin in their salivas were positively correlated for both the isoproterenol (p = 0.01) and the control group (p less than 0.01).

Agonist-induced Ca2+ mobilization in the rat submandibular gland during aging and subsequent to chronic propranolol treatment

The effects of age and chronic propranolol treatment on the agonist-induced rise in intracellular free Ca2+ ([Ca2+]i), an index for the coupling of receptor-second messenger generation, was studied using a dispersed rat submandibular gland preparation. Muscarinic stimulation (10 microns carbachol) caused a rapid (T1/2 less than 2 s) and dramatic (approximately 4.5-fold) rise in [Ca2+]i followed by a lower sustained increase (approximately 3-fold) in [Ca2+]i as measured directly with the Ca(2+)-sensitive fluorescent probe, fura-2. The magnitude and the rate of increase of the initial rise in [Ca2+]i and the level of the sustained increase in [Ca2+]i were not different between 2- an 21-month-old rats. Stimulation in a Ca(2+)-free medium reduced the initial agonist-induced increase in [Ca2+]i by approximately 35-40%, while the sustained increase was abolished by the removal of extracellular Ca2+ from cells in both young and old rats. Chronic treatment for 30 days with 20 mg/kg propranolol, a beta-adrenergic antagonist, did not significantly alter the ability of dispersed submandibular cells in old rats to mobilize Ca2+ during agonist stimulation or influence the in vivo stimulated gland output. These results suggest that the agonist-induced rise in [Ca2+]i is not altered by aging or by chronic treatment of aged rats with propranolol and, therefore, receptor-second messenger coupling remains intact.

Age-related changes in mucins from human whole saliva

The predominant mucins in human whole saliva, MG1 and MG2, serve to protect and to lubricate the oral cavity. In this study, both unstimulated and stimulated whole salivas were collected from two groups of subjects: young (18-35 years of age) and aged (65-83 years of age). The subjects were in apparent good health. Saliva samples from each subject were analyzed by SDS-PAGE. The gels were stained with Stains-all, and both MG1 and MG2 were quantitated by video-image densitometry. The protocol gave reproducible values for each mucin. The stimulated and unstimulated salivas from aged subjects showed significant reductions in concentrations of both MG1 and MG2, as quantitated in mucin dye-binding units. Possible associations of these reductions with the aging process are discussed.